To help filling this gap we measured the audiograms of cormorants Phalacrocorax carbo sinensis and studied their ear anatomy. Wild-caught fledglings were anesthetized and their auditory brainstem response ABR to clicks and tone bursts was measured, first in an anechoic box in air and then in a large water-filled tank with their head and neck submerged 10 cm below the surface. The overall shape of their air-audiograms was like that reported for birds of the same size in air.
The bandwidth and slopes of their audiograms were similar in air and water. However, in air the highest sensitivity was found at 2 kHz, whereas it was displaced towards lower frequencies underwater. These results suggest that cormorants have rather poor in-air hearing compared to similar-sized birds. Their underwater hearing sensitivity, however, is higher than what would have been expected for purely air-adapted ears.
A possible reason for the poor in-air sensitivity is the special ear anatomy with the central eardrum shaped as a rigid piston like in turtles. Internally coupled ears ICE , where an interaural cavity acoustically couples the eardrums, are an anatomical trait present in more than half of all terrestrial vertebrates. The superposition of outside and internal pressure on the two eardrums results in internal instead of interaural time and level differences, which are keys to sound localization.
Although ICE is primarily a low-frequency terrestrial adaptation, the African clawed frog Xenopus laevis is a fully aquatic species with a distinct air-filled canal between the ears. In water, the speed of sound is four times that in air. Unlike terrestrial animals with ICE, the Xenopus interaural cavity is also medially connected to the lungs. By modeling the inflated lungs as a Helmholtz resonator, we demonstrate their effect in improving hearing in a low-frequency regime, while simultaneously enhancing sound localization in a disjoint high-frequency regime, corresponding to the frequency ranges of male advertisement calls.
In conjunction with its unique plate-like eardrums, we show how Xenopus uses its ICE-like interaural coupling to generate considerable internal level differences between eardrum vibrations and thus overcomes the challenges of underwater sound-localization. Taken together, the two arguments of Helmholtz resonator and plate-like eardrums show the potency of ICE and are interpreted accordingly.
While being one of the most densely populated and formerly heavily industrialized regions of Germany, the Ruhr area still offers space for many diverse ecosystems whose preservation is regulated by law. Nevertheless auditory impairments, especially by traffic noise and due to spatial restrictions, are likely. The results of the indices were used in a statistical analysis to investigate 1 correlations between the distance to roads and the amount of biophony and 2 the differences between biophonic soundscape indices in various land uses and ecotones.
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Significant correlations between distance to roads and the amount of biophony and significant differences between soundscapes in different land use types and ecotones were found. Consideration of the results as related to soundscapes and nature reserve policy in Germany are discussed. Giant Pandas have a broader hearing range than humans and have higher sensitivity in different frequency bands. Giant Pandas are known to become stressed when subjected to undesirable noise, therefore noise which humans may deem unobtrusive has the potential to cause stress in Giant Pandas.
As Giant Panda breeding programmes are taking place in zoos throughout the world it is important to understand the impact that anthropogenic noise and vibration has on these mammals and how it affects their wellbeing. This paper discusses the adaptation from international standards on noise and vibration to appropriately address the impact from construction site noise on Giant Pandas; as well as inform the acoustic considerations in the design of a new Giant Panda enclosure at Edinburgh Zoo in Scotland.
The AcouReVe Project aimed to improve the knowledge and the quality of acoustic calculation in ventilation ductworks. Such calculations are based on simplified models and the main issue is the input data. The present work concentrates on sound attenuation across different ventilation network elements, such as bends, branches and manifold.
First a prediction method is described; it involves a multi-modal model pour elements associated to guided waves propagation and a finite elements model for complex elements. Measurements have been performed at CETIAT laboratory on different elements; the experimental setup is described along with the different evaluated configurations. The comparison between the measured results, the predicted results as well as the results from simple standard formulas applicable for the considered elements is presented and discussed in details.
The domestic windows in the building facade has a significant role in sound insulation against outdoor airborne noise. According to the standards, the prediction of their acoustic performances is carried out in laboratory using two reverberant rooms. In this work, various 3D vibroacoustic numerical configurations are studied to discuss the methods proposed by acoustic standards. In particular, we analyze the influence of i the presence of the acoustic cavities and ii the diffuseness of the acoustic field, on the sound reduction index of building elements.
Moreover, due to the complexity of the problem geometry, materials and boundary conditions , an accurate numerical model of the window should be developed. This model, based on the Finite Element Method, is built through a confrontation with experimental tests. For this, a modal analysis is carried out to characterize the vibrational behavior of the structure eigenfrequencies, modal shapes and modal damping.
Those parameters will be used to design an equivalent simplified model of the window, which will enable to carry out parametric analyses. Recent environmental regulations bring up higher standards on acoustic comfort. Thus, the overall sound insulation of such systems depends not merely on glasses but might more on frames and the coupling between them. Particularly when the STC of glass reaches 40 or higher, sound path through the framing elements becomes more critical.
However, this crucial issue has not received enough investigation and no satisfactory approach has been developed in the literature yet. To address this issue, the coupling between aluminum frames and glazing infill was carefully studied, and an extended model has been accordingly developed. A series of laboratory tests with different frames were conducted to validate the predictions.
Materials such as floor coverings, screeds, and resilient matting are commonly applied on top of a floor-ceiling assembly to improve the impact noise insulation. Since the test measures the insulation of the entire assembly, it can be difficult to isolate the effect of these top-side components from the base structural assembly. As a continuation of that program, assemblies and products from historical tests were retested, and the resulting repeatability was poor.
Investigation determined that the cause of the discrepancies was variation in the base assemblies, not the top-side materials. The techniques and results are discussed, and the effect on the interpretation of laboratory testing is evaluated. When predicting the radiation of structure-borne sound into a room, it is often assumed that the generated sound field is diffuse.
A diffuse field is by definition a random field: it represents a conceptual ensemble of rooms with the same volume and total absorption, but otherwise any possible arrangement of boundaries and small objects that scatter incoming sound waves. Adopting a diffuse sound field model therefore inherently introduces uncertainty on the computed results. This uncertainty can be important, especially at the lower frequency end of the spectrum. In this work, practical formulas are derived for predicting not only the mean, but also the variance of energetic level quantities, such as the band-integrated spatially averaged sound pressure level, in a diffuse sound field caused by a mechanically excited structure.
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The formulas are first validated in a simulation study, and then applied for predicting the sound pressure level in a room caused by impact excitation of plate structures. Both the average sound pressure level and its standard deviation can be well predicted. This information is essential e.
The total loss factor measurement by the reverberation method is often performed to estimate the boundary conditions of vibration fields of plate-like structures. In order to clarify how measured values involve discrepancies from the true values, this paper presents a numerical model that simulates the reverberation method to determine the loss factor in a bending vibration system of a glass plate supported with an elastic material. As a reference, the total loss factor of a finite plate system is theoretically calculated based on the diffuse vibration field assumption, where the random-incidence vibration absorption coefficient on the support edge is given for the semi- infinite plate terminated by the mechanical and moment impedances.
Subsequently, the finite element analysis is performed for a rectangular plate with the impedance boundary, and impulse responses are calculated with different arrangements of excitation and receiving points. Comparing the theoretical and numerical results, the validity of the measurement procedures is generally confirmed, however, it is demonstrated that the measured loss factors tend to become slightly higher than theoretical ones.
Additionally, measured results on real window systems are discussed briefly. Heavyweight cavity walls are commonly used as party wall between row houses and between dwellings in apartment buildings in Belgium. The double wall junctions complicate the prediction of flanking transmission. In this paper, empirical rules for the vibration reduction indices of rigid double wall T- and X-junctions are proposed. They are determined from Monte Carlo simulations carried out with a statistical model that was previously validated with laboratory measurements. In general, a double wall junction can be replaced by an equivalent single wall junction in flanking transmission models.
For double wall X-junctions, the thickness of the equivalent single walls should be either the thickness of a single leaf or the total thickness of both double wall leafs, depending on the transmission path of interest. Cross laminated timber CLT as building material has rapidly gained in popularity in recent years, and thereby also the demand of engineering tools to predict the sound insulation through CLT walls. The sound reduction through walls of single and double panels is predicted and the results are compared with those found in the literature as well as with a series of measurements conducted in a test mock-up of two rooms.
Various configurations are considered where the plate thickness, addition of plaster boards and cavity distance in case of a double panel are altered. The prediction of single panel walls is based upon an established model by Sharp for homogenous materials, based upon theory and empirical data.
For optimized application to CLT constructions specifically, the model is modified to some extent. The double panel walls are analytically modelled under the presumptions of no mechanical connection between the two panels and a cavity filled with mineral wool. The model make use of the results from the developed model for individual panels. Prediction of the sound reduction index SRI of modern thermal insulation systems for exterior walls is considered.
These products all have in common a lightweight insulating layer of primarily thermal function which may consist of a porous or non-porous material , and a weatherproof finish; the systems measured in the laboratory included a grout and skim finish or a prefabricated cladding system. In all cases, a typical heavyweight exterior wall was cladded. In their simplest form, such cladding systems can be modelled as a spring-mounted mass.
However, Austrian standards demand that the spring-mounted layer be combined with structural fixings. The SRI of simplified and typical thermal cladding systems i. The possibility to use established methods to determine the coupling loss factors in such combined systems was considered. The structural wall is of heavyweight construction, therefore the SEA problem can be simplified, in many cases, to a primary path analysis.
Several methods have been developed in the past to calculate the sound transmission in building acoustics. However, efficient determination and optimization of the sound insulation capabilities of geometrically complex walls like brick walls or layered wall structures remain a challenging task. In this work, a fully coupled fluid-structure interaction model, based on the frequency-domain spectral element method FDSEM , is proposed to determine the sound insulation of arbitrary wall structures.
A virtual sound measurement laboratory following the guidelines of ISO is designed and used. The calculated frequency responses agree well with the experimental results. Therefore, this method can be used to evaluate the performance of the wall materials and structures in a cost-efficient way. Furthermore, contrary to other methods based on the plate theory, this method is more flexible and avoids many essential simplifications, which could restrict the applicability of the methods in the wall structure optimization.
The present method is implemented in a multi-objective optimization procedure based on a genetic algorithm to optimize various wall structures e. In an early stage of the design the related structural consequences will have to be known very stringently and reliable, because adaptations afterwards are usually not possible.
Within the Peutz office several prediction methods for sound insulation are being used during the design, such as ISO and several own practical methods developed within Peutz, based on more than 65 years of experience. For this project specific high pressure vibration insulated mountings had to be designed and implemented. In order to evaluate the prediction methods used and to prove that the high sound insulations that were predicted have actually been realized, measurements after delivery have to be performed.
Equivalent plate models are commonly used in order to simulate multilayer system as one single layer. This kind of approach enables for instance to reduce the mesh size and thus the number of degrees of freedom in finite element models. Usual condensed model rely on thin plate theory and are obviously limited when considering thick multilayers. In this work we present a comparison of the transmission loss prediction using different analytical models of solid layers: thin plate, thick plate first order shear deformation and 3D modelling 3D linear elasticity. Doing so, analytical limits for the validity of thin and thick plate theories are derived from wavenumber analyses.
Applications to real world cases are presented. Many pre-state societies around the world give special importance to places where special acoustic effects are generated, and often these places receive special treatment including the production of rock paintings in them. In the Western Mediterranean, it seems that outstanding acoustic effects such as directional echoes, augmented audibility and long reverberation time are present in some rock art areas with Neolithic depictions dating between the VII and IV millennia BC painted in Macroschematic, Levantine and Schematic rock art styles.
On the basis of this evidence, it has been argued that there is a strong probability of acoustics having been used as a method by Neolithic artists to select the shelters in which to produce rock art. This paper presents the results of the ongoing ERC research project in archaeoacoustics Artsoundscapes - The sound of special places: exploring rock art soundscapes and the sacred. This project seeks to explore the role of sound in the creation and use of these archaeological sites.
In particular, the authors discuss the results of previous fieldwork in three countries Spain, France and Italy and the development of an innovative set of research methods that includes 3D Ambisonic recordings, Transmission Loss measurements, and GIS soundshed analysis. Nearly 15 years of research on the acoustics of pots from 11th to 18th centuries have led us to crossing data from various disciplines and developing a specific methodology. The presentation analyzes the pitfalls of interpreting this technique through the eyes of the scholars that have addressed the issue since antiquity and of written mentions rather than using the archaeoacoustical data found in France and Europe.
An archaeoacoustic research will only be meaningful if it can prove a deliberate intention to produce an object with an acoustic function. However, such a proof necessitates observing regularities, by studying several buildings or objects that attest that an effective choice has been made. A common error is to restrict the hypotheses to those which are scientifically admissible today. The case of pots acoustics is particularly edifying in this respect. Nevertheless, precise analysis of historical texts makes it possible to widen the field of hypotheses.
Semantic study of the evolution of the meaning of key words and their associated concepts makes it possible to study the evolution of the acoustical techniques and to observe their progress through the centuries. Montivilliers Abbey near Le Havre in France presents a case where pots in the vault were obviously employed to act on the acoustics.
The archives of the abbey contain a written mention that links pots with acoustics. Originally built in the 13th century, the Romanesque vault of the transept crossing was later modified at an unknown date by the addition of pots. In the vault was lowered down, hiding the original pots. A dozen of new pots were inserted in the new vault. The presentation focuses on the acoustics of the abbey and documents the organization of the pots by the builders in the 1st and the 2nd vaults. Room-acoustical measurements of the church were also carried out in order to evaluate its acoustical quality.
A major conclusion is that lowering the vault has singled out the church choir where the nuns chanted and which is characterized by reverberation times lower than in the nave. Intermediate reverberation times were measured in the crossing. Reverberation times in octave Hz, which includes the resonance frequencies of the pots, are marginally lower in the choir and the transept for source in the nave, which could indicate an effect of the pots. The French ECHO project is a multi-disciplinary collaboration combining the efforts of historians, theater scientists, and acousticians to study the use of voice in 20th century French theaters.
These configurations corresponded to a series of renovations, enabling researchers to perceive realistic stage performances in foregone rooms. Simulations include the room, two actors moving on stage, and an audience. To achieve these simulations, archived architectural drawings were studied, providing various details of the different theater configurations from which the corresponding visual and room acoustic geometrical acoustics GA models were created.
Simulations across configurations accommodated the investigation of the impact of these renovations on acoustic conditions, such as reverberation and clarity. These observations can then be compared to historical information, such as theater critics of the time. The largest gatherings in human history prior to the advent of electronic amplification were all effectively limited by the loudness and intelligibility of the human voice.
Various accounts throughout history depict single orators addressing crowds or armies of many tens of thousands, though some historians have cast doubts onto the veracity of these claims. Prior acoustic simulation has shown that reasonable intelligibility might be achieved for up to 20, listeners for very loud orators and very quiet crowds with high density. Nearly all such accounts, however, depict a man addressing the crowd, with one notable exception: in Elizabeth I of England addressed a large army of between 8,, troops gathered to repel the impending invasion posed by the Spanish Armada.
In October the new Environmental Noise Guidelines for the European Region were published by the World Health Organization WHO , providing strong evidence that noise is one of the top environmental hazards to both physical and mental health and well being in Europe. However, recreational noise has not yet been investigated in detail. After a preface about the more recent outcomes on recreational noise provided by EU Guidelines and projects, the current article presents the requirements for noise levels in recreational areas of various categories parks, specially protected areas, reserves, etc.
Moreover, it describes the main existing legal and regulatory acts in the countries, the history of their development and restrictions on their use. Furthermore, the article shows a comparative analysis with the allocation of advantages and disadvantages of each system.
Finally, suggestions have been made to improve the system for regulating noise levels in recreational areas. Noise is one of the inevitable environmental types of pollution especially in densely populated urban areas with the design approach including the recreational places within the residential areas. It is well-known that there are lots of evidence on the health effects of environmental noise and to control this, the improvements have been carrying on in both legislative basis and scientific basis. In the scope of RAMEN, the noise criteria and evaluation procedures are identified for the main noise sources including also entertainment places.
In this paper, recreational noise management in Turkey will be explained and discussed through giving the information on what the main environmental noise criteria for entertainment places is, which authorities responsible for noise audits are, how the procedures to take the music allowance are applied, what requirements of technical staff to conduct the environmental noise measurements and preparing the noise assessment reports are needed. City of Torino Italy , as many European cities, is facing an increasing noise pollution related to recreational noise of nightlife in open urban areas, such as streets, squares and terraces, where thousands of people meet spending all evening and night time.
Noise from people speaking in these spaces can be very loud, due to crowd levels since communication is possible only with a raised voice level and people behaviour. This has led administrations to attempt to manage this specific noise problems with different strategies. This study shows the analysis of long term noise data collected in two years by a low-cost IoT network in Torino. It highlighted the regularities on night levels, mainly on a weekly basis and with seasonal trends.
Preliminary investigations on time series have been developed, in order to correlate noise levels and number of people involved, coupling environmental data and crowd sensors. This approach based on a deeper quantitative knowledge is explored as an help to local administration and stakeholders in planning and implementing mitigation actions. It stipulates the limits for indoor noise levels and sound insulation performance of building elements, and specifies the design criteria of noise control.
The current version was published in , in which requirements had been raised compared to previous version. However, with the rapid development in China during the last decade, current regulations could not meet the growing needs for better sound environment. Traffic noise, HVAC noise and structure-borne noise from service equipment have become increasingly annoying, and inadequate sound insulation aggravates the situation.
Besides, limits for structure-borne noise caused by vibrations of building service equipment or any other noise sources will be introduced to assess the dominant low-frequency noise. The solution to this problem depends on understanding the different situations and contexts in which these terms may be used; understanding the often different requirements of people who use these terms; and reflecting these differences both in the measurement instruments which are actually used and in the constraints and limitations which should be placed on the interpretation of those measurements in different situations and contexts.
In the paper we provide practical examples to illustrate how this problem arises and how it can be solved in real-life situations and contexts. Noise annoyance is a diverse concept. This is reflected by the great variety of different definitions and understandings that exist in the noise impact research community.
Noise annoyance can be defined as an emotion, a rational decision, knowledge, an attitude or the result of a disturbance. Noise annoyance can also be regarded as a multi-dimensional construct that entails some or all of the aspects mentioned above. Currently, most studies on noise annoyance make use of the widely accepted single-item ICBEN question to measure noise annoyance.
There is, however, an ongoing discussion in the research field whether a single-item question can comprehensively cover all facets of noise annoyance. This lead to the postulation of multi-item questionnaires to measure noise annoyance in order to reflect the multi-dimensionality of noise annoyance more adequately.
The current contribution aims to give an overview about different multiple question scale approaches to measure noise annoyance. Its psychometric properties are investigated for aircraft, road, and railway noise annoyance. In this study, we analyse changes in values of the sub-dimension of MIAS for aircraft noise annoyance before and after the opening of a new runway and the implementation of a night curfew in communities around Frankfurt Airport.
Previous studies have shown evidence of a shift in exposure-response relationships for annoyance in situations of changes in noise exposure change effect. This improves the understanding of annoyance in situations of changes in noise exposure. The curve was developed using a statistical regression technique. An extended analysis comprising 46 surveys conducted between and yields a very similar dose-response relationship. There are no obvious temporal trends, and contrary to claims by other researcher the prevalence of highly annoyed residents exposed to road traffic noise today is the same as 45 years ago.
It is said that in the concept of annoyance non-acoustic factors are included as well as physical factors of sounds. Therefore, it is difficult to investigate annoyance in laboratory studies where the situation is somewhat different from daily life situations. Annoyance is usually asked in social surveys. Laboratory studies have merits that various parameters are precisely controlled The authors tried various laboratory studies of annoyance by developing and controlling the experimental methods.
The study using this new method and other laboratory studies of annoyance will be introduced in this paper. Noise research has focused on urban sounds like traffic or machine noise. The present paper, in contrast, investigates low-level sound sources that can affect human wellbeing and health and that are only perceived in specific situations. To address our research questions, we conducted an online survey with around participants representative for the German population. In the course of the survey, participants reported on situations in which they typically noticed low-level sound sources.
They described the characteristics of the sounds as well as their frequency of occurrence. In addition, they reported on typical activities in these specific situations and personal strategies to cope with negative effects. Finally, they filled out questionnaires measuring the Big Five personality traits extraversion and neuroticism as well as noise sensitivity. They further constitute the basis for a multi-level prediction model on the effects of low-level sound sources including situational and person-related factors.
Therefore, the findings contribute to a deeper understanding and to an improvement of low-level acoustic environments. Adverse effects of noise from high-speed railway have become more and more serious and widespread with the rapid development of high-speed rail in China. A social survey on community response to high-speed railway noise was carried out in Tianjin, China from March to July, along the Beijing-Tianjin intercity high-speed rail line and Beijing-Shanghai high-speed rail line. The exposure of high-speed railway noise was measured for 24h at each site, and standardized questions and scales suggested by ICBEN Team 6 were used in the social survey.
As a result, the dose-response relationship curve for high- speed railway noise of Chinese residents was established, and it showed that with the increasing of noise level Ldn , annoyance increased exponentially. Compared with Japanese and French people, Chinese residents showed more annoyed to high- speed railway noise. It also suggested background noise had important impact on noise annoyance evaluation to high-speed railway.
Furthermore, annoyance caused by high-speed railway noise was also greatly influenced by subjective characteristics such as noise sensitivity, satisfaction of living environment and attitudes. Aircraft noise annoyance has been studied for more than 50 years, asking people to rate their annoyance on a unidimensional scale. The importance of non-acoustic factors shows that a more global approach could help to understand how people perceive their acoustic environment. Inspired by the soundscape studies, and in the frame of the ANIMA European project on the impact of aviation noise, an Experience Sampling Method with signal-contingent sampling is chosen to question people in their daily live about the quality of their acoustic and visual environment, and not on the annoyance.
A dedicated mobile application is developed, which collects data each hour of a day night periods are excluded. The experiment lasts two or three weeks depending on the number of notifications per day the participant found acceptable. After the notification, participants are asked to record acoustic measurements third octave bands, each second during one minute. After the questionnaire, participants are asked to take a picture of the environment. Summary questionnaires are filled at the end of each week, and a global questionnaire is filled at the end of the experiment.
This paper focuses on a pilot study whose aim is to evaluate the acceptability of the method by participants. In a longitudinal study, we aim to model short term annoyance due to shooting noise as a function of intra- and inter-individual differences in perceived annoyance by using a hierarchical data modelling approach. The MovisensXS app is used to collect data from three different study sites in Germany from 80 Participants. They are asked to participate within two weeks for a period of five consecutive days per week and, during this time, to fill out a survey, consisting of 19 items, five times a day at set intervals.
This will add up to approximately 4, single measurements, depending on the response rate and the compliance. We describe the methodology of the study, the planning and executional steps taken to ensure a proper data quality. Furthermore, we will explain what has been done to prepare for the data analysis. Finally, we will give a forecast into data analysis and will exemplarily talk about longitudinal data analysis and linear mixed effect modeling.
Over the last decades, cities have been developing noise policies. Comparing such efforts, however, is not a simple task. For this purpose, a previously proposed noise intervention classification scheme is used as a framework. Responsible officers dealing with noise at environmental departments of 8 large European cities were interviewed. The invitations for an interview were sent out taking into account the geographical distribution of cities over Europe while a reasonably high position on a sustainable cities ranking was required.
The interviews focused on the noise problem definition and what is in the noise management toolbox of the city. In addition, it is assessed how noise policies are evaluated, and to what extent public participation in the noise policy and planning process occurs. A decadelong agricultural project spearheaded by Chinese scientists has helped alleviate poverty for more than 1. Many women are unable to conceive and deliver a baby due to genetic problems caused by inherited chromosome abnormalities or single-gene defects.
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It is natural for such a big international project as China's Belt and Road Initiative to be taken by some with a grain of salt. BEIJING -- China will encourage standardized, regular culture and tourism-related volunteer services in , according to a plan by the Ministry of Culture and Tourism that includes three initiatives. A group of scientists in Gansu province have discovered a fossilized bird dating back about million years and the first ever to have an unlaid egg in its abdomen.
The number of Chinese students studying abroad reached , in , up 8. China's efforts to promote the balanced development of compulsory education, which usually means narrowing inter-regional, rural-urban or inter-school gaps in terms of education conditions and quality, has borne fruit, the Ministry of Education said Tue. Scientists have identified seven major genetically distinct groups of the critically endangered Chinese giant salamander - the world's largest amphibian - living in the wild in China, with three in Zhangjiajie, in Central China's Hunan province.
Researchers have unearthed a trove of well-preserved fossils representing more than 50 previously undescribed animal species dating back million years. An international English speaking competition aimed at helping youths from diverse backgrounds gain a deeper understanding of each other's countries and cultures through language and cultural exchanges was held in Hangzhou, Zhejiang province over the week. This year, the Labor Day holiday will be expanded to four days, general office of the State Council saidin a news release on Friday morning.
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Chinese scientists have recently identified a new fish genus living million years ago after they examined four well-preserved specimens discovered in Luoping, eastern Yunnan province. A constant temperature of 27 degrees, a water bowl that never freezes, a comfy mat, and no dogs allowed. People with sleep problems usually think they can adjust by themselves at first and then resort to medication when they fail, according to Guo Xiheng, director of the sleep and respiratory center at Beijing Chaoyang Hospital, Capital Medical University.
Chinese scientists have identified a new protein that restricts HIV infection, which could pave way for development of new antivirus drugs. A grand exhibition to commemorate the 40th anniversary of China's reform and opening-up concluded Wednesday, after receiving 4. China announced that the area of farmland designated to cultivate different crops or lay fallow will increase to 2 million hectares this year, 25 percent more than last year.
Success, according to Chinese wisdom, depends on good timing, a favorable location and human harmony. Chinese scientists identified seven major clades of critically-endangered wild Chinese giant salamander in China, with three clades inhabiting Hunan's Zhangjiajie, a major origin area of the world's existing largest amphibian. In the outline development plan for the Guangdong-Hong Kong-Macao Greater Bay Area, unveiled on Feb 18, authorities set out a framework for building ecological protection barriers.
People across the world want their human rights to be well protected so they can lead a relatively trouble-free and peaceful life. From monitoring cameras to fingerprint attendance systems, universities and colleges continue to adapt in their battle to tackle students' truancy.
China's lunar rover Yutu-2, or Jade Rabbit-2, has driven meters on the far side of the moon and is expected to work longer than its three-month design life. China will push for Artificial Intelligence AI courses to be offered at primary and secondary schools and popularize programming education in steps, according to a directive issued by the Ministry of Education.
A student of Beijing's first and only middle school for children from migrant families recently secured admission at Harvard University, one of the world's most elite institutions. On Friday, the National People's Congress, the country's top legislative body, will vote on the adoption of the draft foreign investment law. China's science ship Tansuo-1 loaded with the manned submersible Shenhai Yongshi Deep Sea Warrior returned to its home harbor in Sanya, South China's Hainan province, on Sunday, after finishing its first expedition in the Indian Ocean.
Preparations for the Olympic and Paralympic Winter Games have reached a key phase in which the construction of most venues has started and the focus has shifted to operations and management of the venues. Like many other foreign experts and academics around the world, Bernard Dewit is among those applauding the draft foreign investment law that will be reviewed at the plenary session of the National People's Congress. BEIJING -China's lunar rover has conducted scientific detection on some stones on the far side of the moon, which might help scientists find out whether they are from outer space or native to the moon.
China will roll out a host of measures to boost development of traditional Chinese medicine TCM , according to a statement issued by the National Administration of Traditional Chinese Medicine. When the two sessions kicks off every year, it is also the time to show some of the latest technologies that could potentially change our lives in the near future. The Government Work Report, delivered by Premier Li Keqiang on Tuesday, received high marks from national lawmakers and netizens, a senior official said.
Xiongan New Area in Hebei province is about to reach full-scale construction stage after a series of plans were finalized in the past two years, a top Xiongan official said on Tuesday. China's Chang'e 4 unmanned lunar mission has been proceeding well and its scientific findings will be made available for free to anyone wishing to access them, according to a key figure in the nation's lunar program. As China works to realize its immense potential as a global tourism destination, more cities have introduced visa-free transit services to make visits easier.
China has made substantial progress in integrating the Guangdong-Hong Kong-Macao Greater Bay Area into a vibrant world-class city cluster, officials said Thursday. China respects freedom of navigation and flights over the South China Sea but resolutely opposes taking it as a pretext to conduct provocative moves in this area, a spokesperson for the Chinese military said Thursday.
A year-old Chinese man has concluded a drive around five continents, ending the last leg in Ushuaia, southern Argentina. Wearing a brightly colored oilcloth apron, year-old Zheng Guoming carefully brushes tung oil on an umbrella cover. Driver Wang Qiang began to learn English on his own since he found there are quite a number of foreigners on the bus, whose route includes the railway station and several commercial areas, the places that are attractive to foreign tourists. Chinese scientists are exploring the possibility of putting in place a space-based solar power station, a futuristic approach expected to reduce pollution back on Earth and mitigate energy shortfalls.
At the annual sessions of the region's people's congress and political advisory body in January, authorities called for more pollution control through greater input and efforts this year. China has decided to promote the development of the home services sector, which business insiders said will boost domestic consumption and attract more investment and professionals to help existing providers improve their services. The first document released by UNESCO on the preservation of language and cultural diversity calls on member countries to combine the protection and promotion of linguistic diversity with the development of science and technology.
Younger adults in Hong Kong and Macao are seeing a bright future north of the border with the release of the long-awaited development outline for the Guangdong-Hong Kong-Macao Greater Bay Area. Chinese media have transformed profoundly over the past year in terms of integrating information and communication technologies and computer networks into media content, a recent blue book shows. Southwest China's Chongqing municipality has piloted a new method of providing parking spaces for food delivery and courier vehicles in order to enhance city management.
For one group of scientists, winter does not bring exciting prospects of skiing or riding snowmobiles. Overseas students in Shanghai had the opportunity to experience the glamor of Kunqu Opera during Lantern Festival celebrations held on Feb For Chinese people who have the tradition of going out on the streets to appreciate the dazzling array of lanterns on display at the annual Lantern Festival, they will have one more beautiful item to gaze upon this year— a super large and bright moon. The number of applicants for art academies in Beijing has reached a new highthis year, makingthe competition even fiercer, Xinhua said.
Palace Museum, or Forbidden City, will extend its opening hours to the evening for the first time on Feb 19 and Feb 20 in celebration for this year's Lantern Festival, its curator said Sunday. The Guangzhou-Shenzhen-Hong Kong express rail link saw passenger numbers surge during its first Spring Festival travel rush. A lion dance team in Southern California, mainly made up of Westerners, has impressed university professor Jia Wenshan.
Five more geographical entities on the moon have been given Chinese names, based on discoveries from China's latest Chang'e 4 mission, according to a news conference on Friday. China's outbound tourism market saw healthy growth in as mainland travelers registered Prices and sales rose at flower markets this week as couples prepared to celebrate Valentine's Day on Thursday.
Chinese tourists made BEIJING - Chinese tech giants reported more user participation in the digital red envelopes during the Spring Festival holiday as Chinese zealously snatched lucky money for good fortune. In a major breakthrough, China has successfully transmitted real-time data to a depth of 6, meters in the ocean using its own Beidou satellites during a scientific expedition, the Chinese Academy of Sciences' Institute of Oceanology said.
The Spring Festival Gala, the world's most watched show of the year, will use advanced technologies this time around such as 5G, virtual reality, augmented reality and artificial intelligence, to provide a more immersive and interactive experience for aud. China announced on Thursday that it has mastered the core technologies to build the world's brightest synchrotron radiation light source, and that it expects to be able to produce the most powerful X-rays by In September, a train carrying porcelain and tea pulled out of the railway station in Jingdezhen, Jiangxi province, headed for Moscow in Russia.
China's largest online travel agency Ctrip has made available red packets containing foreign currency on its brick-and-mortar stores and online platform ahead of the Spring Festival this year. Today, the 24th day of the last lunar month, is observed among millions of Chinese and Asian Americans as a mini festival, better known as xiao nian in Chinese. Train attendant Sun Mingjin is working through his 39th Spring Festival travel rush, which began on Jan 21 and will not officially end until March 1. China's major train maker on Saturday tested a new generation of maglev train with a designed speed of km per hour, about 60 percent faster than the current model, in Changsha, capital of Central China's Hunan province.
Monday marked the start of Chunyun, the annual day travel peak that straddles Spring Festival. Tens of millions of people began heading home ahead of Chinese New Year, which falls on Feb 5. Every morning during Spring Festival, a Russian woman appears at Hunchun Railway Station, which is served by China's high-speed rail network, in Jilin province. At the station, she answers passengers' questions in Chinese and Russian. On Wednesday morning, Zhang Aiping joined hundreds of migrant workers as he began his journey home by motorcycle for a Spring Festival family reunion.
No cell phones, no digital cameras, and no smart wearable devices - the Guizhou provincial government has revised a regulation to keep the noise down and prevent human activities from affecting the world's largest telescope. Shanghai scientists have located brain areas corresponding to smoking and drinking, bringing new insights and opening possibilities for stopping addictive behavior.
China's transport authorities are busy getting ready for the Spring Festival travel rush starting Monday, with 3 billion trips expected to be made. Literature professor Dai Jianye became famous online when video clips of his accented, humorous and insightful interpretations of ancient poems went viral on a popular short video platform, drawing nearly 2 million fans. Hanuman the monkey god, one of the central characters in the ancient Hindu epic Ramayana, is considered a symbol of devotion. Yu Min, a nuclear physicist widely known as the father of China's hydrogen bomb, died on Wednesday at the age of Chinese universities dominate this year's rankings of emerging economies universities, according to data published Wednesday afternoon.
A second wave of measures has been released to encourage Chinese innovation by promoting intellectual property rights protection, transforming technological achievements into products, and delegating more power to universities and research professionals. The Chinese Academy of Sciences will release about 5 million gigabytes of data related to Earth sciences, biology and ecology from around globe, allowing scientists and officials worldwide to study and tackle issues in climate change, food security, disas. A human skull found near China's border with Mongolia and Russia is more than 10, years old, researchers announced on Saturday.
Hair loss has become a buzzword for young people in China as a way to show the stress they experience in daily lives, according to a recent survey by the China Youth Daily. Chinese researchers have conducted preliminary topographical analysis of the landing site of the country's Chang'e 4 lunar probe, the China National Space Administration said on Friday. New data shows celebrating Spring Festival by traveling to big cities is becoming a new trend among Chinese this year. China will step up its basic research efforts, enhance innovative capabilities, increase international cooperation and improve its supervision and regulation regarding academic misconduct and unethical practices this year, China's top science official sai.
Try to picture life-size terracotta sculptures by your side as you eat, sleep and use the bathroom. AI-powered imaging became the most mature field within the intelligence and medical science industry last year. Heads of British universities say they will be forced to recruit a higher proportion of students from foreign nations, including China, should Brexit mean that the United Kingdom becomes ineligible for education funding from the European Union.
Ahead of the Spring Festival travel rush, million railway tickets were sold between Dec 23, , and Jan 6, , according to the China Railway Corporation. BEIJING - China's Chang'e 4 probe has started the exploration on the far side of the moon thanks to the relay satellite that provides a communication link with ground control.
A longer Fuxing bullet train made its debut on Saturday whose 17 cars make room for 90 additional passengers. A People's Liberation Army Air Force brigade is determined to become a pioneering, world-class aviation force that is always ready to fight and sure to win. Interest in travel for those over 60 years old grew in , and their passion for trips is expected to continue to increase this year, travel agencies said.
A system of government-run new media outlets, led by those operated by the central government's gov. After decades of running her own business, Zhang Huamei, 58, from the Lucheng district in Wenzhou, Zhejiang province, plans to retire next year. The checkpoint of Hong Kong-Zhuhai-Macao Bridge in Zhuhai special economic zone in Guangdong province has granted a total of visas upon arrival to foreigners and another exit and entry travel documents to Hong Kong and Macao residents since it was.
Archaeologists in north China's Hebei Province have discovered a new Great Wall relic built during the Ming Dynasty to guard against northern invaders. In the s, Mo Xiaohui was one of millions of migrant workers in Shenzhen, Guangdong province, the front line of reform and opening-up at the time. If Bai Wen hadn't returned to his home village four years ago, he might have been an outstanding researcher at an institute in Lishui, in the eastern province of Zhejiang, studying the cultivation of wild mushrooms. This is the last story in a series reflecting China's achievements in a range of fields, including science, law enforcement, education and transportation, resulting from 40 years of the reform and opening-up policy.
In addition to Song Zhenzhong's exhibition in Dongcheng district, many other events have been held across Beijing to mark the 40th anniversary of reform and opening-up. China's National High-Tech Industrial Development Zones, the backbone of the country's high-technology industries, have made major progress in innovation capabilities since The upcoming New Year holiday has prompted young Chinese people's passion to travel, a report from China's online travel service provider Tuniu. With solid progress for more than two years, China is on track to achieve major objectives for the second half of this decade, the National Development and Reform Commission, the top economic regulator, said on Monday.
A host of shared self-service mini-gymnasiums, each covering about 5 square meters, have sprung up in China's major cities, including Beijing. With the world's largest number of internet users, the country is a growing cyberspace powerhouse. Wang Keju reports. Striving and the 40th anniversary of reform and opening-up have been respectively chosen as the Chinese Character and Word of the Year in China, according to a survey released Thursday.
The number of candidates to sit the entrance exam for postgraduate studies from Dec 22 to 24 will reach a record high of 2. Cao Yuan, a year-old doctoral candidate in physics at the Massachusetts Institute of Technology, was named one of the 10 people who mattered this year by the journal Nature on Wednesday for discovering a magic angle in graphene sheets that spurred a.
Destinations featuring snow scenery and winter sports like skiing have seen a boom in tourism over the past month, according to a report by Tuniu. British science journal Nature has ranked a young Chinese scientist among its top people for When he applied for scholarships for overseas study as a year-old high school graduate in Cambodia with an interest in computers, Heng Piseth never thought he would one day study in the Guangxi Zhuang autonomous region. China's 35th Antarctic expedition team have begun a feasibility study into building an airfield on a large sheet of blue ice.
More young Chinese believe their country is changing for the better and identify with its development path, a recent survey says. Experts attending a tourism forum in Beijing said health tourism featuring the traditional Chinese medicine TCM is embracing a golden time for development. When it comes to rocket science, nuts and bolts may appear to some people to be the least-complicated parts. Wang Huiping would argue otherwise. The blood for clinical use in China now entirely comes from voluntary blood donations, according to Zhou Changqiang, an official from the country's National Health Commission NHC on Thursday.
China's reform and opening up has helped liberate and develop social productive forces, opened up a path of socialism with Chinese characteristics, and ushered in a new chapter in the development of human rights, according to a white paper issued Wednesda. A whopping 80 percent of Chinese college students report feeling more motivated to study and enjoy life when being in a romantic relationship, according to a new survey.
A map of China, made with seeds of rice, corn, wheat and other crops has caught the eyes of visitors at the Nanfan Scientific and Research Breeding Base. China will launch a reference range exclusively for Chinese children's blood test indicators next year, according to the Beijing Evening News on Monday.
The tide of China's opening-up has been a great help for the preservation of Dunhuang's ancient relics, according to the city's head of cultural heritage protection. Seats have been set aside on public buses in two cities in China for passengers willing to volunteer to intervene in passenger disputes with bus drivers, reports China National Radio. If you are concerned that your child will be nearsighted, a new artificial intelligence model developed from millions of eyesight records could help predict whether your offspring will need glasses.
China will expand the implementation of a series of pro-innovation reform measures to further drive innovation and creativity, a State Council executive meeting chaired by Premier Li Keqiang decided on Wednesday. A cold wave sweeping across the country has pushed the mercury down by 6 to 8 C across much of central and eastern China.
The delivery of plaques to 10 new Confucius Institutes at the opening ceremony of the 13th Confucius Institute Conference in Chengdu, Sichuan province, on Tuesday. The gold and silver commemorative coins issued by the central bank to celebrate the 40th anniversary of reform and opening-up are now available, Chinanews. Do not glissade when you see a sign in a washroom telling you to Slide carefully! An online version of an exhibition at Beijing's National Museum of China to mark the 40th anniversary of reform and opening-up has been launched. Hundreds of people from around the country visit Jinggangshan, in eastern China's Jiangxi province, each day to retrace the revolutionary generation's footsteps.
China will complete its first undersea tunnel for high-speed trains by , connecting the Zhoushan Islands in eastern Zhejiang province with the mainland, according to local authorities. A five-year-old boy known as Little Stone has become a livestreaming star with over one million views — thanks to the way he resembles Buddha, Jilin Daily reports. Chinese researchers have developed an online database providing detailed, integrated biological data on domestic and wild dog species. As needlelike larch leaves fall like golden snowflakes in the mountains of Youyu county, it is hard to imagine the forests are the result of generations of human effort rather than a gift of nature.
China's central bank has decided to issue a set of banknotes and coins to commemorate the 70th anniversary of the renminbi, and the yuan special banknote will circulate on the market with face value. China has decided to build a number of key hubs for the logistics sector and improve its efficiency and information-sharing as part of efforts to substantially reduce the ratio of overall logistics costs to GDP, and build a modern logistics system. The exhibition to commemorate the 40th anniversary of China's reform and opening-up has received more than , visits as of Nov 26, according to the exhibition office Monday.
China-Malaysia Qinzhou Industrial Park in the Guangxi Zhuang autonomous region aims to explore a new model in cross-border cooperation between such parks, said Gao Pu. Russian chemist Konstantin Chingin's contribution to Sino-Russian academic cooperation in his chosen research field, mass spectrometry, was recognized on Sept 29 when he received the Chinese government's Friendship Award. The heroic deeds of Liu Chuanjian, a Chinese pilot who was applauded after successfully handing an emergency landing, will hit screens in China.
China will launch a pilot program aimed at getting more women to give birth naturally with painkillers to reduce the frequency of C-sections. More Chinese universities have joined a program that encourages the recycling of cardboard used for packaging billions of items dispatched after the country's annual shopping spree on Nov Paleontologists have identified over dinosaur footprints in Yiwu in eastern China's Zhejiang Province after a dinosaur research project concluded its excavation stage.
Yuan Longping, known as the world father of hybrid rice, has won the life science section of the Future Science Prize, with two other scientists. China is slated to become world's largest theme park market by , when the number of tourists is expected to exceed million, according to a fresh report by US engineering firm AECOM.
Louise Brown, the first human born via the in vitro fertilization, or IVF, made her debut in China on Thursday afternoon as she addressed at the 12th annual meeting of the Chinese Society of Reproductive Medicine, held in Southwest China's Chongqing. When Chinese explorer Zheng He commanded expeditionary voyages and opened up the Maritime Silk Road about years ago, it was the stars that helped him navigate his fleet through the boundless oceans.
College students from Northeast China's Heilongjiang province have taken photos of the moon's far side via microsatellite, Dutch TV broadcaster NOS reported on its website. People lined up on Wednesday to visit a major exhibition in Beijing commemorating the 40th anniversary of China's reform and opening-up. China Railway Corp put on extra high-speed trains and cargo routes to meet the increased demand for parcel delivery following the Chinese shopping festival known as Double 11, or Singles Day.
More than 3, students from more than 20 countries and regions involved in the Belt and Road Initiative have shown interest in studying at Chinese business schools. One of China's top universities, Peking University, will establish a new campus in Changping district, focusing on artificial intelligence research, Beijing Youth Daily reported on Tuesday.
BEIJING - A pilot who made a successful emergency landing in May has been honored as one of China's 20 most beautiful veterans of , authorities announced at an honoring ceremony. China has mastered a field of cutting-edge aviation technology that is currently dominated by the United States and Russia, which is expected to give the nation's fighter jets better combat capability. Forty-five are alive, bringing the total number of captive pandas globally to , said Li Chunliang, deputy director of the National Forestry and Grassland Administration. A traditional Chinese medicine official urged further improving the core competitiveness of traditional Chinese medicine through innovation.
Engineers are developing a new carrier rocket to launch China's next-generation manned spacecraft into low-Earth orbits or as far as the moon, said China Aerospace Science and Technology Corp, a major space contractor. China's ancient medical remedy of acupuncture is gaining global popularity after proving to be an effective treatment for illnesses and ailments that Western medicine still struggles to cure. China started a project on Tuesday to build its first large, domestically made cruise ship, a major stride in the nation's shipbuilding capabilities.
A recent ordinance on keeping dogs in the urban area of a county-level city in Southwest China's Yunnan province has aroused spirited public debate, most opposing the ordinance, since it stipulated dog owners could not walk their dogs from 7 am to 10 pm.
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By examining the brain's medial entorhinal cortex, the researchers discovered a previously unknown set of neurons that turn on like a clock when. For something business consultant Jeff Oliveira, winter vacations mean hitting the slopes of the Altay Mountains in the Xinjiang Uygur autonomous region. China's home-grown global satellite navigation system came a step closer to completion with the launch of another BeiDou-3 satellite at pm Thursday from the Xichang Satellite Launch Center, in the southwestern Sichuan Province. Readers across China continue to pay tribute to celebrated author Louis Cha Leung-yung, remembering him as a guru of martial arts novels and a source of inspiration in their adolescence and beyond.
China's job market grew steadily during the first three quarters of the year, as the country's registered unemployment rate fell to 3. On a rainy day earlier in October, the chilly weather didn't cool the enthusiasm of visitors to Yan'an in northern Shaanxi province. A recently concluded China-Russia joint Arctic expedition has yielded a more comprehensive and systematic understanding of the Arctic Ocean that will provide scientific support for the development of a Polar Silk Road, scientists from the two countries sa.
China's first space router has been successfully launched atop the Long March-4B carrier rocket from the Taiyuan Satellite Launch Center in northern Shanxi province. A survey reported Thursday by the China Youth Daily showed that around half of the respondents could accept a bare-bones marriage, or getting married without any major assets or a grand wedding ceremony.
China is making headway in ensuring agricultural products safety, with It was and Mao Zedong, one of the most influential figures of the 20th century, was still a student at a teacher training college in Changsha, Hunan province. Chinese engineers are developing the nation's second generation of manned spacecraft which will be tasked with servicing the country's space station and participating in manned lunar missions, said a researcher involved with the program.
Thousands of passengers vied to be among the first to ride over the world's longest sea span, as the Hong Kong-Zhuhai-Macao Bridge opened for traffic at 9 am Wednesday morning. Finally, the successful total synthesis of 1 is discussed. The development of a short, highly convergent route 14 steps in the longest linear sequence is highlighted by the cyclization of enynoylindole 40 with acetylene and the formal intramolecular 1,8-conjugate addition of amine 49 to form pentacycle Numerous attempts toward the formation of the piperidine ring of 1 from vinyl iodide 56 were made and its successful formation via palladium-, nickel-, and radical-mediated processes is described.
The present method has been employed to construct synthetically valuable bicyclo[3. As a further synthetic application, a stereoselective synthesis of 5,methanomorphanthridinone, which shares a key skeleton with montanine-type Amaryllidaceae alkaloids has been achieved by using this chemistry. Nitrone Cycloadditions of 1,2-Cyclohexadiene. Barber, Joyann S. We report the first 1,3-dipolar cycloadditions of 1,2-cyclohexadiene, a rarely exploited strained allene.
The reactions occur regioselectively and exhibit a notable endo preference, thus resulting in the controlled formation of two new bonds and two stereogenic centers. DFT calculations of stepwise and concerted reaction pathways are used to rationalize the observed selectivities. Moreover, the strategic manipulation of nitrone cycloadducts demonstrates the utility of this methodology for the assembly of compounds bearing multiple heterocyclic units.
These studies showcase the exploitation of a traditionally avoided reactive intermediate in chemical synthesis. On the mechanism of nitrosoarene-alkyne cycloaddition. Taken together the experimental and computational results point to the operation of a stepwise diradical cycloaddition , with rate-limiting N-C bond formation and rapid C-C connection to form a bicyclic cyclohexadienyl-N-oxyl diradical, followed by fast tautomerization to the N-hydroxyindole product. Switchable regioselectivity in amine-catalysed asymmetric cycloadditions.
Building small-molecule libraries with structural and stereogenic diversity plays an important role in drug discovery. The development of switchable intermolecular cycloaddition reactions from identical substrates in different regioselective fashions would provide an attractive protocol. However, this also represents a challenge in organic chemistry, because it is difficult to control regioselectivity to afford the products exclusively and at the same time achieve high levels of stereoselectivity. All of the cycloaddition reactions exhibit excellent regio- and stereoselectivity, producing a broad spectrum of chiral architectures with high structural diversity and molecular complexity.
Nickel-catalyzed cycloadditions of unsaturated hydrocarbons, aldehydes, and ketones. The nickel-catalyzed cycloaddition of unsaturated hydrocarbons and carbonyls is reported. Diynes and enynes were used as coupling partners. Carbonyl substrates include both aldehdyes and ketones. Reactions of diynes and aldehydes afforded the [3,3] electrocyclic ring-opened tautomers, rather than pyrans, in high yields.
The cycloaddition reaction of enynes and aldehydes afforded two distinct products. A new carbon-carbon bond is formed, prior to a competitive beta-hydrogen elimination of a nickel alkoxide, between the carbonyl carbon and either one of the carbons of the olefin or the alkyne. The steric hindrance of the enyne greatly affected the chemoselectivity of the cycloaddition of enynes and aldehydes.
In some cases, dihydropyran was also formed. The scope of the cycloaddition reaction was expanded to include the coupling of enynes and ketones. No beta-hydrogen elimination was observed in cycloaddition reaction of enynes and ketones. Instead, C-O bond-forming reductive elimination occurred exclusively to afford dihydropyrans in excellent yields. In all cases, complete chemoselectivity was observed; only dihydropyrans where the carbonyl carbon forms a carbon-carbon bond with a carbon of the olefin, rather than of the alkyne, were observed.
All cycloaddition reactions occur at room temperature and employ nickel catalysts bearing the hindered 1,3-bis 2,6-diisopropylphenyl imidazolylidene IPr or its saturated analogue, 1,3-bis 2,6-diisopropylphenyl -4,5-dihydroimidazolinylidene SIPr. Reactions of diynes and aldehydes afforded the [3, 3] electrocyclic ring-opened tautomers, rather than pyrans, in high yields. Instead, C—O bond-forming reductive elimination occurred exclusively to afford dihydropyrans in excellent yields. In all cases, complete chemoselectivity was observed; only dihydropyrans where the carbonyl carbon forms a carbon—carbon bond with a carbon of the olefin, rather than of the alkyne, were observed.
Mechanism of Indole acetic Acid Conjugation. Formation of indole acetic acid-aspartate in detached primary leaves of cowpea Vigna sinensis Endl. When leaves were preincubated with ethylene Rhizobitoxine 1. This strategy has been widely studied under thermal, photochemical and microwave induced conditions.
More recently, the use of transition metal catalysis has been introduced as an alternative relying on the activation of the allenic component. On the other hand, the intramolecular version has attracted much attention as a strategy for the synthesis of polycyclic compounds in a regio- and stereoselective fashion. Rapid cycloaddition of a diazo group with an unstrained dipolarophile. This second-order rate constant rivals those of optimized strain-promoted azide- alkyne cycloadditions , even though the reaction does not release strain.
Analogous reactions with an azidoacetamide dipole or with an acrylate or crotonate dipolarophile were much slower. These findings suggest a new strategy for the design of diazo-selective reagents for chemical biology. Peptidomimetics via copper-catalyzed azide-alkyne cycloadditions. This critical review concerns the impact of copper-mediated alkyne-azide cycloadditions on peptidomimetic studies.
It discusses how this reaction has been used to insert triazoles into peptide chains, to link peptides to other functionalities e. It will be of interest to those studying this click reaction, peptidomimetic secondary structure and function, and to medicinal chemists.
Molecular Characterization of Indolent Prostate Cancer. Introduction Indolent prostate cancers that pose very low risk to aged men occur frequently and may be detected at biopsy, leading to the The scope of the proposed research is: 1 to. The development of a series of novel indole -based inhibitors of 5'-inosine monophosphate dehydrogenase IMPDH is described. Various hydrogen bond acceptors at C-3 of the indole were explored. The synthesis and the structure-activity relationships SARs derived from in vitro studies are outlined.
Indole Alkaloids from Chaetomium globosum. Two new indole alkaloids chaetocochin J 1 and chaetoglobinol A 8 , along with chetomin 2 , chetoseminudin A 3 , cochliodinol 9 , and semicochliodinol 10 , were isolated from the rice culture of the fungus Chaetomium globosum. Their structures were elucidated by spectral analysis. Three new epipolythiodioxopiperazines, chaetocochins G-I , were identified by the combination of UPLC and mass spectrometric analysis.
Chaetocochin I contained two sulfur bridges, one formed by three sulfur atoms between C-3 and Ca, and the other formed by four sulfur atoms between C-3' and C-6'. Chaetocochin I was readily transformed into chetomin 2 , chetoseminudin A 3 , chaetocochin D 4 , chaetocochin G 5 , and chaetocochin H 6 by losing sulfur atoms. Compounds , and 8 exhibited antibacterial activities against Bacillus subtilis with MICs of 25, 0.
The superoxide anion radical scavenging assay indicated that compounds , and 8 showed Diels-Alder cycloadditions of 3-oxobutenyl substituted orthoquinone monoketals with olefinic dienophiles furnished functionalized ortho-endo bicyclo[2. The competition between self-dimerization and Diels-Alder cycloaddition with an external dienophile usually exists, except in the case of 5-substituted orthoquinone monoketal.
While intermolecular and intramolecular variants are widely known, transannular versions of this reaction are unknown and the basis of this study. Macrocyclic enyne and dienyne complexes were readily synthesized by palladium II -catalyzed oxidative macrocyclizations of bis vinyl boronate esters or ring-closing metathesis reactions followed by complexation with dicobalt octacarbonyl. Several reaction modalities of these macrocyclic complexes were uncovered. The structural and reaction requirements for each process are presented. Bioorthogonal tetrazine cycloadditions have been applied to live cell labeling.
Tetrazines react irreversibly with the strained dienophile norbornene forming dihydropyrazine products and dinitrogen. The reaction is high yielding, selective, and fast in aqueous media. Tetrazines conjugated to a near-infrared fluorochrome selectively and rapidly label the pretargeted antibody in the presence of serum. These findings indicate that this chemistry is suitable for in vitro labeling experiments, and suggests that it may prove a useful strategy for in vivo pretargeted imaging under numerous modalities.
Bis ketenimines , in which the two heterocumulenic functions are placed in close proximity on a carbon skeleton to allow their mutual interaction, show a rich and not easily predictable chemistry. In addition, nitrogen-to-carbon [1,3] and [1,5] shifts of arylmethyl groups in N-arylmethyl-C,C-diphenyl ketenimines are also disclosed. Indole -containing compounds are best known for their medicinal properties in the pharmaceutical industry. Although to a lesser degree, the indole motif none-the-less appears in many significant products across the entire chemical industry.
This chapter describes the role that indole plays in a more commodity setting and provides examples illustrating these uses. Biotransformation of indole derivatives by mycelial cultures. Biotransformation of tryptophan to tryptamine and 3-methyl- indole by Psilocybe coprophila was performed. On the other hand, Aspergillus niger was able to transform tryptophan to 5-hydroxy-tryptophan. These results prove once more that fungi are good tools to establish hydroxyindole derivatives.
In this report, we reverse this reactivity and drive the 1,3-dipoles to serve as electrophiles by employing 3-alkylated indoles as nucleophiles. This represents the first use of VCPs for the completely atom-economic functionalization of 3-substituted 1 H- indoles and tryptophan derivatives via a Pd-catalyzed asymmetric allylic alkylation Pd-AAA. Excellent yields and high chemo-, regio-, and enantioselectivities have been realized, providing various indolenine and indoline products.
The method is amenable to gram scale and works efficiently with tryptophan derivatives that contain a diketopiperazine or diketomorpholine ring, allowing us to synthesize mollenine A in a rapid and ligand-controlled fashion. The obtained indolenine products bear an imine, an internal olefin, and a malonate motif, giving multiple sites with diverse reactivities for product diversification. Complicated polycyclic skeletons can be conveniently constructed by leveraging this unique juxtaposition of functional groups.
Selectivity in Ketenimine Cycloadditions. Photoelectron Hel Spectra of Ketenimines. The relevance of these results on the site selectivity observed in cycloaddition reactions of these species is discussed. The Copper-nicotinamide complex: sustainable applications in coupling and cycloaddition reactions. Crystalline copper II -nicotinamide complex, synthesized via simple mixing of copper chloride and nicotinamide solution at room temperature, catalyzes the C-S, C-N bond forming and cycloaddition reactions under a variety of sustainable reaction conditions.
It is well known that the amino-acid tryptophan is particularly stable in the interfacial region of biological membranes, and this preference is a property of the tryptophan side-chain. Analogues of this side-chain, such as indole , strongly localize in the interfacial region, especially near the glycerol moiety of the lipids in the bilayer. Using molecular dynamics calculations, we determine the potential of mean force PMF for indoles in the bilayer. We compare the calculated PMF for indole with that of benzene to show that exclusion from the center of the lipid bilayer does not occur in all aromatics, but is strong in indoles.
We find three minima in the PMF. Indole is most stabilized near the glycerol moiety. A weaker binding location is found near the choline groups of the lipid molecules. An even weaker binding side is found near the center of the lipid hydrocarbon core. High temperature simulations are used to determine the relative contribution of enthalpy and entropy to indole localization. The orientation of indole is found to be largely charge independent and is a strong function of depth within the bilayer. We find good agreement between simulated SCD order parameters for indole and experimentally determined order parameters.
Iron-catalyzed intermolecular cycloaddition of diazo surrogates with hexahydro-1,3,5-triazines. We report here an unprecedented iron-catalyzed cycloaddition reaction of diazo surrogates with hexahydro-1,3,5-triazines, providing five-membered heterocycles in moderate to high yields under mild reaction conditions. This cycloaddition features C-N and C-C bond formation using a cheap iron catalyst. Fluorogenic reactions, in which non- or weakly fluorescent reagents produce highly fluorescent products, are attractive for detecting a broad range of compounds in the fields of bioconjugation and material sciences.
Herein, we report that a dibenzocyclooctyne derivative modified with a cyclopropenone moiety Fl-DIBO can undergo fast strain-promoted cycloaddition reactions under catalyst-free conditions with azides, nitrones, nitrile oxides, as well as mono- and disubstituted diazo-derivatives.
Although the reaction with nitrile oxides, nitrones, and disubstituted diazo compounds gave cycloadducts with low quantum yield, monosubstituted diazo reagents produced 1H-pyrazole derivatives that exhibited an approximately fold fluorescence enhancement over Fl-DIBO combined with a greater than 10,fold increase in brightness. The fluorogenic probe Fl-DIBO was successfully employed for the labeling of diazo-tagged proteins without detectable background signal.
Diazo-derivatives are emerging as attractive reporters for the labeling of biomolecules, and the studies presented herein demonstrate that Fl-DIBO can be employed for visualizing such biomolecules without the need for probe washout. Fluorogenic reactions in which non- or weakly-fluorescent reagents produce highly fluorescent products are attractive for detecting a broad range of compounds in the fields of bio-conjugation and material sciences. We report here that Fl-DIBO, a dibenzocyclooctyne derivative modified with a cyclopropenone moiety, can undergo fast strain-promoted cycloadditions under catalyst-free conditions with azides, nitrones, nitrile oxides as well as mono- and disubstituted diazo-derivatives.
Diazo-derivatives are emerging as attractive reporters for the labeling of biomolecules and the studies presented here demonstrate that Fl-DIBO can be employed for visualizing such biomolecules without the need for probe washout. Indole compounds may be promising medicines for ulcerative colitis. Indole compounds are extracted from indigo plants and have been used as blue or purple dyes for hundreds of years.
In traditional Chinese medicine, herbal agents in combination with Qing-Dai also known as indigo naturalis have been used to treat patients with ulcerative colitis UC and to remedy inflammatory conditions. Recent studies have noted that indole compounds can be biosynthesized from tryptophan metabolites produced by various enzymes derived from intestinal microbiota. In addition to their action on indole compounds, the intestinal microbiota produce various tryptophan metabolites that mediate critical functions through distinct pathways and enzymes.
Furthermore, some indole compounds, such as indigo and indirubin, act as ligands for the aryl hydrocarbon receptor. This signaling pathway stimulates mucosal type 3 innate lymphoid cells to produce interleukin, which induces antimicrobial peptide and tight junction molecule production, suggesting a role for indole compounds during the mucosal healing process. Thus, indole compounds may represent a novel treatment strategy for UC patients. In this review, we describe the origin and function of this indole compound-containing Chinese herb, as well as the drug development of indole compounds.
Indole alkaloids from leaves and twigs of Rauvolfia verticillata. Seven new indole alkaloids, rauverines A-G , and 19 known indole alkaloids were isolated from the leaves and twigs of Rauvolfia verticillata. Microwave-assisted synthesis of medicinally relevant indoles. Indoles represent an important structural class in medicinal chemistry with broad spectrum of biological activities.
The synthesis of indoles , therefore, has attracted enormous attention from synthetic chemists. Microwave methods for the preparation of indole analogs have been developed to speed up the synthesis, therefore, microwave assisted organic synthesis MAOS in controlled conditions is an invaluable technique for medicinal chemistry. In this review, indole forming classical reactions such as Fischer, Madelung, Bischler-Mohlau, Batcho-Leimgruber, Hemetsberger-Knittel, Graebe-Ullmann, Diels-Alder and Wittig type reactions using microwave radiation has been summarized.
In addition, metal mediated cyclizations along with solid phase synthesis of indoles have been discussed. New pathway for the biodegradation of indole in Aspergillus niger. Indole and its derivatives form a class of toxic recalcitrant environmental pollutants. The growth of Aspergillus niger was inhibited by very low concentrations 0. When 0. Indole was metabolized by a new pathway via indoxyl 3-hydroxyindole , N-formylanthranilic acid, anthranilic acid, 2,3-dihydroxybenzoic acid, and catechol, which was further degraded by ortho cleavage.
The enzymes N-formylanthranilate deformylase, anthranilate hydroxylase, 2,3-dihydroxybenzoate decarboxylase, and catechol dioxygenase were induced by indole as early as after 5 h of growth, and their activities were demonstrated in a cell-free system. Electrophilicity: the "dark-side" of indole chemistry.
Indole is by far one of the most popular heterocyclic scaffolds in nature. The intriguing and challenging molecular architectures of polycyclic, naturally occurring indolyl compounds constitute a continuous stimulus for development in organic synthesis. The field had a formidable boom across the new millennium when catalysis started revolutionizing the chemistry of indole , providing always more convincing and sustainable solutions to the selective "decoration" of this pharmacophore.
A common guideline of these approaches relies on the intrinsic overexpression of electron density of the indole core. Despite less diffusion, the "dark-side" of indole reactivity, electrophilicity, has been also elegantly documented with direct applications towards the realization of specific interatomic connections that would be difficult to obtain by means of conventional indole reactivity.
The present Perspective article summarizes the major findings that brought the research area from the pioneering findings of the 60s to the state of the art. Pd II complexes gave oxidation resistant, bis-pyrrole fused adducts. This undergraduate organic laboratory experiment consists of three different reactions occurring in the same flask: a cycloaddition reaction, preceded by decarboxylation and nucleophilic substitution reactions.
The decarboxylation and cycloaddition reactions occur using identical Cu I catalyst and conditions. Orange, lemon, and other citrus fruit…. These reactions feature the use of a gold complex to accomplish the diverse annulations and the first example of the involvement of a gold metallo-enolcarbene in a cycloaddition. It is also the first utilization of stable triazines as formal dipolar adducts in the carbene-involved cycloadditions. Mechanistic investigations reveal that the triazines reacted directly, rather than as formaldimine precursors, in the reaction process.
The copper I -catalyzed azide-alkyne cycloaddition CuAAC reaction has found broad application in myriad fields. For the most demanding applications requiring high yields at low substrate concentrations, highly active but air-sensitive copper complexes must be used. We describe here the use of an electrochemical potential to maintain catalysts in the active Cu I oxidation state in the presence of air. The simple procedure efficiently achieves excellent yields of CuAAC products involving both small molecule and protein substrates without the use of potentially damaging chemical reducing agents.
A new water-soluble carboxylated version of the popular tris benzyltriazolylmethyl amine TBTA ligand is described. Under the influence of a mV potential established using a reticulated vitreous carbon working electrode, CuSO4 and 3 formed a superior catalyst. Electrochemically protected copper I -catalyzed azide-alkyne cycloaddition. For the most demanding applications that require high yields at low substrate concentrations, highly active but air-sensitive copper complexes must be used. This simple procedure efficiently achieves excellent yields of CuAAC products from both small-molecule and protein substrates without the use of potentially damaging chemical reducing agents.
A new water-soluble carboxylated version of the popular tris benzyltriazolylmethyl amine TBTA ligand is also described. Under the influence of a mV potential that was established by using a reticulated vitreous carbon working electrode, CuSO4 and 3 formed a superior catalyst.
Electrochemically protected bioconjugations in air were performed by using bacteriophage Qbeta that was derivatized with azide moieties at surface lysine residues. Complete derivatization of more than reactive sites per particle was demonstrated within 12 h of electrolysis with substoichiometric quantities of Cu3. Copper-catalyzed azide alkyne cycloaddition polymer networks.
The click reaction concept, introduced in , has since spurred the rapid development and reexamination of efficient, high yield reactions which proceed rapidly under mild conditions. Prior to the discovery of facile copper catalysis in , the thermally activated azide-alkyne or Huisgen cycloaddition reaction was largely ignored following its discovery in large part due to its slow kinetics, requirement for elevated temperature and limited selectivity.
Now, arguably, the most prolific and capable of the click reactions, the copper-catalyzed azide alkyne cycloaddition CuAAC reaction is extremely efficient and affords exquisite control of the reaction. The orthogonally and chemoselectivity of this reaction enable its wide utility across varied scientific fields. Despite numerous inherent advantages and widespread use for small molecule synthesis and solution-based polymer chemistry, it has only recently and rarely been utilized to form polymer networks.
This work focuses on the synthesis, mechanisms, and unique attributes of the CuAAC reaction for the fabrication of functional polymer networks. The aliphatic amine ligands were used as an electron transfer species to reduce Cu II upon irradiation with nm light while also functioning as an accelerating agent and as protecting ligands for the Cu I that was formed.
The sequential and orthogonal nature of the photo. Phosphine-catalyzed cycloadditions of allenic ketones: new substrates for nucleophilic catalysis. A range of phosphine-catalyzed cycloaddition reactions of allenic ketones have been studied, extending the scope of these processes from the more widely used 2,3-butadienoates to allow access to a number of synthetically useful products.
The results from other reactions that had found utility with 2,3-butadienoates are also reported. Isoxazolodihydropyridinones: 1,3-dipolar cycloaddition of nitrile oxides onto 2,4-dioxopiperidines. Practical and efficient methods have been developed for the diversity-oriented synthesis of isoxazolodihydropyridinones via the 1,3-dipolar cycloaddition of nitrile oxides onto 2,4-dioxopiperidines.
A select few of these isoxazolodihydropyridinones were further elaborated with triazoles by copper catalyzed azide-alkyne cycloaddition reactions. A total of 70 compounds and intermediates were synthesized and analyzed for drug likeness.
The diazo group has untapped utility in chemical biology. The tolerance of stabilized diazo groups to cellular metabolism is comparable to that of azido groups. However, chemoselectivity has been elusive, as both groups undergo 1,3-dipolar cycloadditions with strained alkynes. Removing strain and tuning dipolarophile electronics yields diazo group selective 1,3-dipolar cycloadditions that can be performed in the presence of an azido group. For example, diazoacetamide but not its azido congener react with dehydroalanine residues, as in the natural product nisin.
Diazo compounds, which can be accessed directly from azides by deimidogenation, are shown to be extremely versatile dipoles in 1,3-dipolar cycloaddition reactions with a cyclooctyne. The reactivity of a diazo compound can be much greater or much less than its azide analog, and is enhanced markedly in polar-protic solvents. These reactivities are predictable from frontier molecular orbital energies.
The most reactive diazo compound exhibited the highest known second-order rate constant to date for a dipolar cycloaddition with a cycloalkyne. These data provide a new modality for effecting chemoselective reactions in a biological context. The first experimental examples of Diels-Alder DA reactions of diazo compounds as heterodienophiles with dienes have been studied with density functional theory DFT using the MX functional.
The 1,3-dipolar cycloaddition is strongly favored for the intermolecular system. Synthesis of Trifluoromethylated Isoxazolidines: 1,3-Dipolar Cycloaddition of Nitrosoarenes, Trifluoromethyl diazomethane, and Alkenes. Isoxazolidines have proven to be important substrates in synthetic organic chemistry.
Limited examples in the literature that provide trifluoromethylated versions of these compounds have prompted us to investigate a 1,3-dipolar cycloaddition route providing access to N-functionalized isoxazolidines containing a trifluoromethyl group. Thus, a 1,3-dipolar cycloaddition of nitrosoarenes, trifluoromethyl diazomethane, and alkenes was developed. The starting materials can be synthesized from easy to handle and accessible reagents. The reaction proved to be tolerant of a variety of electron-deficient alkenes and nitrosoarenes. Diels-Alder cycloaddition in the synthesis of 1-azafagomine, analogs, and derivatives as glycosidase inhibitors.
This comprehensive review deals with the synthesis of 1-azafagomine, analogs, and derivatives having the Diels-Alder cycloaddition as the key step. Most of the compounds referred are racemic or have been resolved by lipase transesterification. There are two asymmetric cycloadditions leading to 1-azafagomine or to an analog. In one case both enantiomers of 1-azafagomine were prepared together with a pair of derivatives. The study comprises glycosidase inhibition studies of the target compounds to a set of glycosidic enzymes, and evidenced molecular features that enhance or diminish their activity as glycosidase inhibitors.
Hexacyclic monoterpenoid indole alkaloids from Rauvolfia verticillata. Five new hexacyclic monoterpenoid indole alkaloids, rauvovertine A 1 , epi-rauvovertine A 2 , rauvovertine B 3 , epi-rauvovertine B 4 , and rauvovertine C 5 together with 17 known analogues were isolated from the stems of Rauvolfia verticillata. The structures of were established by spectroscopic analysis and with the aid of molecular modeling. A radiochemical synthesis is described for [14C] indole methanesulfonic acid IMS , a strongly acidic auxin analog.
Techniques were developed for fractionation and purification of IMS using normal and reverse phase chromatography. In addition, the utility of both Fourier transform infrared spectrometry and fast atom bombardment mass spectrometry for analysis of IMS has been demonstrated.
IMS was shown to be an active auxin, stimulating soybean hypocotyl elongation, bean first internode curvature, and ethylene production. IMS uptake by thin sections of soybean hypocotyl was essentially independent of solution pH and, when applied at a micromolar concentration, IMS exhibited a basipetal polarity in its transport in both corn coleoptile and soybean hypocotyl sections.
Electron attachment to indole and related molecules. Modelli, Alberto, E-mail: alberto. Gas-phase formation of temporary negative ion states via resonance attachment of low-energy 0—6 eV electrons into vacant molecular orbitals of indoline I , indene II , indole III , 2-methylen-1,3,3-trimethylindoline IV , and 2,3,3-trimethyl-indolenine V was investigated for the first time by electron transmission spectroscopy ETS. The description of their empty-level structures was supported by density functional theory and Hartree-Fock calculations, using empirically calibrated linear equations to scale the calculated virtual orbital energies.
The same theoretical method is also used for evaluation of the thermodynamic energy thresholds for production of the negative fragments observed in the DEA spectra. The gas-phase DEAS data can provide support for biochemical reaction mechanisms in vivo involving initial hydrogen abstraction from the nitrogen atom of the indole moiety, present in a variety of biologically important molecules.
Indole can act as an extracellular signal to regulate biofilm formation of Escherichia coli and other indole -producing bacteria. We demonstrated previously that genetic inactivation of tryptophanase is responsible for a dramatic decrease in biofilm formation in the laboratory strain Escherichia coli S In the present study, we tested whether the biochemical inhibition of tryptophanase, with the competitive inhibitor oxindolyl-L-alanine, could affect polystyrene colonization by E.
Oxindolyl-L-alanine inhibits, in a dose-dependent manner, indole production and biofilm formation by strain S grown in Luria-Bertani LB medium. Supplementation with indole at physiologically relevant concentrations restores biofilm formation by strain S in the presence of oxindolyl-L-alanine and by mutant strain E. Oxindolyl-L-alanine also inhibits the adherence of S cells to polystyrene for a 3-h incubation time, but mutant strain cells are unaffected. In conclusion, these data suggest that indole , produced by the action of tryptophanase, is involved in polystyrene colonization by several indole -producing bacterial species.
Indole may act as a signalling molecule to regulate the expression of adhesion and biofilm-promoting factors. Translocation of radiolabeled indole acetic acid and indole acetyl-myo-inositol from kernel to shoot of Zea mays L. Either 5-[3H] indole acetic acid IAA or 5-[3H] indole acetyl-myo-inositol was applied to the endosperm of kernels of dark-grown Zea mays seedlings. The distribution of total radioactivity, radiolabeled indole acetic acid, and radiolabeled ester conjugated indole acetic acid, in the shoots was then determined. Differences were found in the distribution and chemical form of the radiolabeled indole acetic acid in the shoot depending upon whether 5-[3H] indole acetic acid or 5-[3H] indole acetyl-myo-inositol was applied to the endosperm.
We demonstrated that indole acetyl-myo-inositol applied to the endosperm provides both free and ester conjugated indole acetic acid to the mesocotyl and coleoptile.