Mechano luminescence(ML),which involves the emission of light under mechanical stimuli,shows great potential in various applications such as sensing,imaging,and energy harvesting.Current research suggests that the lum...Mechano luminescence(ML),which involves the emission of light under mechanical stimuli,shows great potential in various applications such as sensing,imaging,and energy harvesting.Current research suggests that the luminescence mechanism of ML is typically connected to specific defects present within the material.In this study,we focus on the investigation of ML defects in Pr^(3+)-doped NaNbO_(3)/LiNbO_(3)heterojunctions,employing a combination of experimental and theoretical approaches.Through experimental analysis,we confirmed the presence of the heterojunction and its influence on ML intensity,and the optimal doping ratio for the heterojunction in ML was established.Furthermore,we examined the influence of varying Pr^(3+)doping concentrations on ML behavior and a proof-of-concept was demonstrated using the X-rays charged heterostructural phosphor as a stress sensor for biological applications.The position and concentration of internal defects in the ML material were scrutinized through thermo luminescence tests employing the variable heating rate method and positron annihilation.Complementing the experimental findings,theoretical simulations were conducted to elucidate the underlying mechanisms responsible for the observed ML defects.Density functional theory calculations were employed to investigate the energy levels,charge transfer processes,and lattice distortions within the heterojunctions under mechanical stress.Theoretical predictions were compared and validated against the experimental results.The integration of experimental and theoretical approaches provides a comprehensive understanding of the ML behavior of Pr^(3+)-doped NaNbO_(3)/LiNbO_(3)heterojunctions.The insights gained from this research contribute to the development of novel ML materials and pave the way for their applications in next-generation sensing and energy conversion devices.展开更多
Driven by global environmental concerns,many efforts have been made to develop halogen-free flame retardants for rigid polyurethane foam(RPUF).These environmentally benign flame retardants are mainly divided into(i)re...Driven by global environmental concerns,many efforts have been made to develop halogen-free flame retardants for rigid polyurethane foam(RPUF).These environmentally benign flame retardants are mainly divided into(i)reactive,(ii)additive,and(iii)coating types.The last decade has witnessed great progress of these three strategies,which enhance the fire safety of RPUF and maintain even improve the thermal insulation properties.This comprehensive review focuses on the up-to-date design of the reactive,additive,and coating flame retardants,and their effects on flame retardancy and thermal conductivity of RPUF.Moreover,the practical applications of the as-prepared flame-retardant RPUFs are highlighted.Finally,key challenges associated with these three kinds of flame retardants are discussed and future research opportunities are also proposed.展开更多
A velocity model is an important factor influencing microseismic event locations. We re- view the velocity modeling and inversion techniques for locating microseismic events in exploration for unconventional oil and g...A velocity model is an important factor influencing microseismic event locations. We re- view the velocity modeling and inversion techniques for locating microseismic events in exploration for unconventional oil and gas reservoirs. We first describe the geological and geophysical characteristics of reservoir formations related to hydraulic fracturing in heterogeneity, anisotropy, and variability, then discuss the influences of velocity estimation, anisotropy model, and their time-lapse changes on the accuracy in determining microseismic event locations, and then survey some typical methods for building velocity models in locating event locations. We conclude that the three tangled physical attributes of reservoirs make microseismic monitoring very challenging. The uncertainties in velocity model and ignoring its anisotropies and its variations in hydraulic fracturing can cause systematic mislocations of microseismie events which are unacceptable in microseismic monitoring. So, we propose some potential ways for building accurate velocity models.展开更多
In order to improve the efficiency of 3D near-surface velocity model building, we develop a layer-stripping method using seismic first-arrival times. The velocity model within a Common Mid-Point （CMP） gather is assu...In order to improve the efficiency of 3D near-surface velocity model building, we develop a layer-stripping method using seismic first-arrival times. The velocity model within a Common Mid-Point （CMP） gather is assumed to be stratified into thin layers, and the velocity of each layer var- ies linearly with depth. The thickness and velocity of the top layer are estimated using minimum-offset first-arrival data in a CMP gather. Then the top layer is stripped and the second layer becomes a new top layer. After removing the effect of the top layer from the former first-arrival data, the new first-arrival data are obtained and then used to estimate the parameters of the second layer. In this manner, the velocity model, being regarded as that at a CMP location, is built layer-by-layer from the top to the bottom. A 3D near-surface velocity model is then formed using the velocity models at all CMP locations. The tests on synthetic and observed seismic data show that the layer-stripping method can be used to build good near-surface velocity models for static correction, and its computation speed is approximately hundred times faster than that of grid tomography.展开更多
The seawater column is typically taken as a homogeneous velocity layer in wide-angle crustal seismic surveys in marine environments. However, heterogeneities in salinity and temperature throughout the seawater layer r...The seawater column is typically taken as a homogeneous velocity layer in wide-angle crustal seismic surveys in marine environments. However, heterogeneities in salinity and temperature throughout the seawater layer result insignificant lateral variations in its seismic velocity, especially in deep marine environments. Failure to compensate for these velocity inhomogeneities will introduce significant artifacts in constructing crustal velocity models using seismic tomography. In this study, we conduct numerical experiments to investigate the impact of heterogeneous seismic velocities in seawater on tomographic inversion for crustal velocity models. Experiments that include lateral variation in seawater velocity demonstrated that the modeled crustal velocities were contaminated by artifacts from tomographic inversions when assuming a homogeneous water layer. To suppress such artifacts, we propose two strategies：（1） simultaneous inversion of water velocities and the crustal velocities;（2） layer-stripping inversion during which to first invert for seawater velocity and then correct the travel times before inverting for crustal velocities. The layer-stripping inversion significantly improves the modeling of variation in seawater velocity when preformed with seismic sensors deployed on the ocean bottom and in the water column. Such strategies improve crustal modeling via wide-angle seismic surveys in deep-marine environment.展开更多
Fabricating a high-performing thermoset using bio-based flame retardant is critical for the sustain-able development of engineering materials with superior fire safety and robust mechanical properties.Herein,the epoxy...Fabricating a high-performing thermoset using bio-based flame retardant is critical for the sustain-able development of engineering materials with superior fire safety and robust mechanical properties.Herein,the epoxy(EP)composites with the industrial requirements are manufactured with a novel high-efficient,lignin-based flame retardant named DAL-x,which is fabricated by grafting 9,10-dihydro-9-oxa-10-phosphaze-10-oxide(DOPO)onto lignin.The resulting DAL-x/EP composite exhibits excellent flame retardancy with a desirable UL-94 V-0 rating and a satisfactory limiting oxygen index(LOI)of 29.8%due to the appropriate phosphorus content of DAL-x with adjustable molecular chain structure.More-over,the DAL-x/EP composite shows an unexpected improvement in the elastic modulus(∼36%)and well-preserved strength and ductility compared with those of pure EP.This work offers a feasible strat-egy for creating efficient bio-based flame retardants utilizing industrial waste lignin and preparing high-performance EP composites that meet the demanding requirement of fire retardancy in industries,con-tributing to the circular economy and sustainability.展开更多
Clustering earthquakes refer to the seismic events that occur closely with each other in time and space. Because their overlapping waveform records make it difficult to pick the first arrivals, the hypocenters of clus...Clustering earthquakes refer to the seismic events that occur closely with each other in time and space. Because their overlapping waveform records make it difficult to pick the first arrivals, the hypocenters of clustering earthquakes cannot be determined accurately by traveltime location methods. Here we apply a reverse-time imaging （RTI） method to map clustering earthquakes. Taking the advantage of directly using waveforms, the RTI method is capable to map either a single small earthquake or some densely distributed clustering earthquakes beneath a 2-D seismic array. In 3-D case the RTI method is successfully applied to locate the long-offset doublet earthquakes using the data from a set of sparsely distributed surface stations. However, for the same acquisition geometry, the RTI encounters challenges in mapping densely distributed clustering earthquakes. While it is obvious that improving the mapping of clustering earthquakes requires a denser receiver network with wider range of illumination angles, it is necessary to verify the actual resolution of the RTI method with synthetic data. In our study area in the Three Gorges region, our tests in 3-D case suggest that some events beneath the linear aligned sub-arrays have reasonable resolution.展开更多
OBJECTIVE： The study was undertaken to explore a bibliometric approach to quantitatively assess the research on detection of monosialoganglioside from 2002 to 2011. DATA RETRIEVAL： A bibliometric analysis based on t...OBJECTIVE： The study was undertaken to explore a bibliometric approach to quantitatively assess the research on detection of monosialoganglioside from 2002 to 2011. DATA RETRIEVAL： A bibliometric analysis based on the publications on Web of Science was performed using key words such as ＂monosialoganglioside＂, ＂colloidal gold＂, ＂high performance liquid chromatography＂ and ＂detection＂. SELECTION CRITERIA： （1） Research articles on the detection of monosialoganglioside; （2） researches on human and animal fundamentals, clinical trials and case reports; （3） article types： article, review, proceedings paper, note, letter, editorial material, discussion, book chapter; （4） Publication year： 2002-2011. Exclusion criteria： （1） unrelated articles; （2） type of articles： correction; （3） articles from following databases： all databases related to social science and arts ＆ humanities in Web of Science were excluded. MAIN OUTCOME MEASURES： （1） distribution of subject areas; （2） number of publications annually; （3） document type and language of publications; （4） distribution of institutions; （5） distribution of output in journals; （6） the number of countries in which the article is published; （7） top cited paper. RESULTS： Overall population stands at 1 880 research articles addressing detection of monosialoganglioside in Web of Science during the study period. Articles （1 599） were the most frequently used document type comprising 85.05%, followed by meeting abstracts, reviews and proceedings papers. The distribution of subject categories showed that monosialoganglioside research covered both clinical and basic science research. The USA, Japan, and Italy were the three most productive countries, and the publication numbers in the USA were highest with 559 papers. The University of Milan, Nagoya University, and Kinki University are the most productive institutions regarding detection of monosialoganglioside. In 559 articles published by Americans, Medical College of Georgia ranked the first with 30 articles, followed by University of Medicine and Dentistry of New Jersey （28 articles）, Cornell University （24 articles） and Johns Hopkins University （24 articles）. In 442 articles published by Japanese, Nagoya University ranked the first with 40 articles, followed by Kinki University （36 articles）, and Dokkyo University （31 articles）. Though the total number of publications by Japanese is smaller than Americans, the top three institutions published more publications than American institutions. There is a markedly increase in the number of publications on the subject detection of monosialoganglioside in 2004, which the peak in the past 10 years. The valley bottom of the subject appeared in 2005. In total, the research is increased with time prolonged. Journal of Neurochemistry, Journal of Biological Chemistry and Journal of Neuroimmunology were core subject journals in monosialoganglioside studies. CONCLUSION： This study highlights the topics in detection of monosialoganglioside research that are being published around the world.展开更多
Suppression of the inner energy dissipation,related to the lattice phonons and inner defects,in lanthanide doped upco nversion luminescent materials remains a formidable challenge.Herein,we reveal an energy cycling st...Suppression of the inner energy dissipation,related to the lattice phonons and inner defects,in lanthanide doped upco nversion luminescent materials remains a formidable challenge.Herein,we reveal an energy cycling strategy capable of suppressing the inner energy dissipation in lanthanide doped upconversion nanocrystals.Yb^(3+)ions were introduced in Er^(3+)heavily doped nanocrystals as an energy reservoir to compete with the inner energy dissipation.The detailed energy cycling processes between Er^(3+)activator and Yb^(3+)reservoir,responsible for the enhancement of Er^(3+)upconversion intensity,are proposed and further verified on the basis of spectral observations.The energy cycling strategy,with unique merits like facile and cost-effective preparation as well as broad scope of application,is highly valuable in lanthanide luminescent nano materials.展开更多
Eariy-arrival waveform tomography （EWT） is one of the most promising techniques for building near-surface velocity model. Based on finite-frequency wave equation, EWT estimates velocities by matching calculated earl...Eariy-arrival waveform tomography （EWT） is one of the most promising techniques for building near-surface velocity model. Based on finite-frequency wave equation, EWT estimates velocities by matching calculated early-arrival waveforms with the observed ones. However, the objective function of EWT can easily converge to local minimum because of the cycle-skipping phenomenon. In order to reduce the cycle-skipping problem, a hybrid-domain early-arrival waveform tomography （HEWT） is proposed in this paper. The forward modeling of HEWT is realized in the time domain where early-arrival waveforms are easier to be selected from seismic data and less memory is needed than they are in the frequency domain. The inversion is implemented in the frequency domain where multi-scale strategy is more convenient to be realized than that in the time domain. Discrete Fourier transformation （DFT） is used to transform the time-domain wavefield to the frequency-domain wavefield. Test results show that HEWT is more competitive than EWT in both accuracy and computational time.展开更多
A long life election spin resonance (ESR) signal at g=2.0006 was observed in the normal lens epithelium and cortical fibers. During ultraviolet (UV) exposure, a new ESR signal at g = 2.0060 was found in the lens epith...A long life election spin resonance (ESR) signal at g=2.0006 was observed in the normal lens epithelium and cortical fibers. During ultraviolet (UV) exposure, a new ESR signal at g = 2.0060 was found in the lens epithelium. But this specific signal was not detected in the lens cortical fibers. This suggested that lens epithelial cells were more susceptible to the free radical formation which was induced by UV light. By means of ESR spin probe oxymetry, the oxygen uptake of lens epithelial cells was meas...展开更多
We propose and experimentally demonstrate a long-range chaotic Brillouin optical correlation domain analysis by employing an optimized time-gated scheme and differential denoising configuration,where the number of eff...We propose and experimentally demonstrate a long-range chaotic Brillouin optical correlation domain analysis by employing an optimized time-gated scheme and differential denoising configuration,where the number of effective resolving points largely increases to more than one million.The deterioration of the chaotic Brillouin gain spectrum(BGS)and limitation of sensing range owing to the intrinsic noise structure,resulting from the time delay signature(TDS)and nonzero background of chaotic laser,is theoretically analyzed.The optimized time-gated scheme with a higher extinction ratio is used to eliminate the TDS-induced impact.The signal-to-background ratio of the measured BGS is enhanced by the differential denoising scheme to furthest remove the accumulated nonzero noise floor along the fiber,and the pure chaotic BGS is ulteriorly obtained by the Lorentz fit.Ultimately,distributed strain sensing along a 27.54-km fiber with a 2.69-cm spatial resolution is experimentally demonstrated,and the number of effective resolving points is more than 1,020,000.展开更多
BACKGROUND： The monosialoganglioside （GM1） is a popular topic of research but the bibliometric analysis of GM1 over the decades in Science Citation Index-Expanded （SCI-E） remains poorly understood. OBJECTIVE： To...BACKGROUND： The monosialoganglioside （GM1） is a popular topic of research but the bibliometric analysis of GM1 over the decades in Science Citation Index-Expanded （SCI-E） remains poorly understood. OBJECTIVE： To identify the global research and to improve the understanding of research trends in the GM1 field from 1942 to 2011. DESIGN： A bibliometric study. DATA RETRIEVAL： We performed a bibliometric analysis based on the SCI-E published by the Institute of Scientific Information. INCLUSIVE CRITERIA： Articles closely related to GM1 were included. Exclusive criteria： （1） Articles related to gangliosidosis, disialo-ganglioside, trisialo-ganglioside or ganglioside GQIb. （2） Document types such as meeting abstracts, reviews, proceedings papers, notes, and letters. MAIN OUTCOME MEASURES： （1） Type of publication output; （2） number of author outputs; （3） distribution of output in subject categories; （4） publication distribution of countries; （5） distribution of output in journals, and （6） distribution of citations in each decade. RESULTS： During 1942 to 2011, there were 10 126 papers on GM1 that were added to the SCI. Articles （8 004） were the most frequently used document type comprising 79.0%, followed by meeting abstracts, reviews and proceedings papers. Research on GM1 could be found in the SCI from 1942, it was developed in the 1970s, greatly increased in the 1980s, and reached a peak in the 1990s, and it was slightly decreased in 2000. The distribution of subject categories showed that GM1 research covered both clinical and basic science research. The USA, Japan, and Germany were the three most productive countries, and the publication numbers in the USA were highest in all decades. The Joumal of Biological Chemistry, Journal of Neurochemistry and Biochemistry were core subject journals in GM1 studies in each decade. CONCLUSION： This study highlights the topics in GM1 research that are being published around the world.展开更多
An efficient enantioselective Michael addition of ethyl-2-cyanoacetate and diethyl malonate to α,β-unsaturated ketones catalyzed by a simple chiral Schiff base, and products were obtained in good yields at room temp...An efficient enantioselective Michael addition of ethyl-2-cyanoacetate and diethyl malonate to α,β-unsaturated ketones catalyzed by a simple chiral Schiff base, and products were obtained in good yields at room temperature.展开更多
Helicobacter pylori, the major cause of gastritis, peptic ulcer and gastric cancer, infects half of the world population, but only a few infections lead to serious disease. In order to investigate specific proteins re...Helicobacter pylori, the major cause of gastritis, peptic ulcer and gastric cancer, infects half of the world population, but only a few infections lead to serious disease. In order to investigate specific proteins related to the pathogenic difference of this bacterium, comparative proteome analyses of Helicobacter pylori C1 (isolated from patients with gastric cancer) and G1 (isolated from patients with gastritis) were performed using two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). Four proteins (inorganic pyrophosphatase, 3-oxoadipate CoA-transferase subunit B, translation elongation factor, and aldo-keto reductase) were found only in Helicobacter pylori C1, and one protein (alkyl hydroperoxide reductase) was found in G1. Additionally, different isoelectric points (pI) of Hsp60 were observed from the two strains. Then we cloned and sequenced Hsp60 genes from forty-nine Helicobacter pylori isolated from gastric cancer and gastritis. Gene sequencing showed that one C→G single nucleotide polymorphism occurred in the 1399th nucleotide of Hsp60. These results indicate that pathogenic differences exist in various Helicobacter pylori isolated from Chinese patients.展开更多
A series of novel pyrazoles compounds were synthesized by the reaction of five kinds of substitute α-bromoacetophenone with pyrazole intermediates which was prepared by the reaction of chalcones and thiosemicarbazone...A series of novel pyrazoles compounds were synthesized by the reaction of five kinds of substitute α-bromoacetophenone with pyrazole intermediates which was prepared by the reaction of chalcones and thiosemicarbazones. This method has some advantages such as mild reaction condition, easy operation and higher yield. All the compounds were confirmed by elemental analysis, IR and 1H NMR.展开更多
We demonstrate a white light fiber source based on Bismuth and Erbium co-doped fiber and a single 830nm laser diode pump. The light spectral intensity from 1100 to 1570nm is over -45dBm, which provide ~40dB dynamic ra...We demonstrate a white light fiber source based on Bismuth and Erbium co-doped fiber and a single 830nm laser diode pump. The light spectral intensity from 1100 to 1570nm is over -45dBm, which provide ~40dB dynamic range for an OSA based spectral measurement.展开更多
We demonstrate a smart optical fiber sensor unit to realize a multi-parameter sensing, including temperature, curvature and strain or displacement. The sensor unit is composed of a Bragg grating in graded-index multim...We demonstrate a smart optical fiber sensor unit to realize a multi-parameter sensing, including temperature, curvature and strain or displacement. The sensor unit is composed of a Bragg grating in graded-index multimode fiber and a Fizeau cavity.展开更多
Background:Research has indicated that the disease burden of alopecia areata(AA)in China exceeds the global average.Therefore,accurate and updated epidemiological information is crucial for policymakers.In this study,...Background:Research has indicated that the disease burden of alopecia areata(AA)in China exceeds the global average.Therefore,accurate and updated epidemiological information is crucial for policymakers.In this study,we aimed to comprehensively assess the disease burden of AA in China.Methods:The following four key indicators were utilized:the prevalence of cases;disability-adjusted life-years(DALYs);the age-standardized prevalence rate(ASPR);and the age-standardized DALY rate(ASDR)of AA according to the Global Burden of Disease(GBD)study 2021.We analyzed the epidemiological burden of AA in China during 2021,examined changes between 1990 and 2021,and performed a Bayesian age-period-cohort analysis to predict trends over the course of the next decade(2022-2030).Additionally,a Gaussian process regression model was applied to estimate the relationship between the gross domestic product(GDP)and the ASPR and ASDR of AA at the provincial level between 1992 and 2021.Results:In 2021,the estimated number of patients with AA in China was approximately 3.49 million(95%uncertainty interval[UI],3.37-3.62 million);of these patients,1.20 million(95%UI,1.16-1.25 million)were male and 2.29 million(95%UI,2.20-2.37 million)were female.This large number of patients with AA resulted in a total of 114,431.25 DALYs(95%UI,74,780.27-160,318.96 DALYs).Additionally,the ASPR and ASDR were 224.61 per 100,000 population(95%UI,216.73-232.65 per 100,000 population)and 7.41 per 100,000 population(95%UI,4.85-10.44 per 100,000 population),respectively;both of these rates were higher than the global averages.The most affected demographic groups were young and female individuals 25-39 years of age.Slight regional disparities were observed,with the northern and central regions of China bearing comparatively higher burdens.Between 1990 and 2021,the health loss and disease burden caused by AA in China remained relatively stable.The ASPR and ASDR of AA increased with the GDP when the annual GDP was less than 2 trillion Chinese yuan;however,a downward trend was observed as the GDP surpassed 2 trillion Chinese yuan.A slight upward trend in the disease burden of AA in China is predicted to occur over the next decade.Conclusions:AA continues to be a public health concern in China that shows no signs of declining.Targeted efforts for young individuals and females are necessary because they experience a disproportionately high burden of AA.展开更多
基金supported by the National Natural Science Foundation of China(52201008,52372003)Natural Science Foundation of Heilongjiang Province of China(ZD2023E004)+1 种基金Fundamental Research Funds for the Central Universities(3072020CF2515,3072022CFJ2504)the State Key Laboratory of Particle Detection and Electronics(SKLPDE-KF-202311)。
文摘Mechano luminescence(ML),which involves the emission of light under mechanical stimuli,shows great potential in various applications such as sensing,imaging,and energy harvesting.Current research suggests that the luminescence mechanism of ML is typically connected to specific defects present within the material.In this study,we focus on the investigation of ML defects in Pr^(3+)-doped NaNbO_(3)/LiNbO_(3)heterojunctions,employing a combination of experimental and theoretical approaches.Through experimental analysis,we confirmed the presence of the heterojunction and its influence on ML intensity,and the optimal doping ratio for the heterojunction in ML was established.Furthermore,we examined the influence of varying Pr^(3+)doping concentrations on ML behavior and a proof-of-concept was demonstrated using the X-rays charged heterostructural phosphor as a stress sensor for biological applications.The position and concentration of internal defects in the ML material were scrutinized through thermo luminescence tests employing the variable heating rate method and positron annihilation.Complementing the experimental findings,theoretical simulations were conducted to elucidate the underlying mechanisms responsible for the observed ML defects.Density functional theory calculations were employed to investigate the energy levels,charge transfer processes,and lattice distortions within the heterojunctions under mechanical stress.Theoretical predictions were compared and validated against the experimental results.The integration of experimental and theoretical approaches provides a comprehensive understanding of the ML behavior of Pr^(3+)-doped NaNbO_(3)/LiNbO_(3)heterojunctions.The insights gained from this research contribute to the development of novel ML materials and pave the way for their applications in next-generation sensing and energy conversion devices.
基金financially supported by the Australian Research Council(Nos.DP190102992,FT190100188)the National Natural Science Foundation of China(No.51873196)the Key Research and Development Projects of Zhejiang Province(No.2019C01098)。
文摘Driven by global environmental concerns,many efforts have been made to develop halogen-free flame retardants for rigid polyurethane foam(RPUF).These environmentally benign flame retardants are mainly divided into(i)reactive,(ii)additive,and(iii)coating types.The last decade has witnessed great progress of these three strategies,which enhance the fire safety of RPUF and maintain even improve the thermal insulation properties.This comprehensive review focuses on the up-to-date design of the reactive,additive,and coating flame retardants,and their effects on flame retardancy and thermal conductivity of RPUF.Moreover,the practical applications of the as-prepared flame-retardant RPUFs are highlighted.Finally,key challenges associated with these three kinds of flame retardants are discussed and future research opportunities are also proposed.
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education (No.20130132110023)by the National Natural Science Foundation of China (Nos.41230318,41074077)
文摘A velocity model is an important factor influencing microseismic event locations. We re- view the velocity modeling and inversion techniques for locating microseismic events in exploration for unconventional oil and gas reservoirs. We first describe the geological and geophysical characteristics of reservoir formations related to hydraulic fracturing in heterogeneity, anisotropy, and variability, then discuss the influences of velocity estimation, anisotropy model, and their time-lapse changes on the accuracy in determining microseismic event locations, and then survey some typical methods for building velocity models in locating event locations. We conclude that the three tangled physical attributes of reservoirs make microseismic monitoring very challenging. The uncertainties in velocity model and ignoring its anisotropies and its variations in hydraulic fracturing can cause systematic mislocations of microseismie events which are unacceptable in microseismic monitoring. So, we propose some potential ways for building accurate velocity models.
基金supported by the National Natural Science Foundation of China(Nos.41230318,41074077)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20130132110023)the Fundamental Research Funds for the Central Universities of China(No.201413004)
文摘In order to improve the efficiency of 3D near-surface velocity model building, we develop a layer-stripping method using seismic first-arrival times. The velocity model within a Common Mid-Point （CMP） gather is assumed to be stratified into thin layers, and the velocity of each layer var- ies linearly with depth. The thickness and velocity of the top layer are estimated using minimum-offset first-arrival data in a CMP gather. Then the top layer is stripped and the second layer becomes a new top layer. After removing the effect of the top layer from the former first-arrival data, the new first-arrival data are obtained and then used to estimate the parameters of the second layer. In this manner, the velocity model, being regarded as that at a CMP location, is built layer-by-layer from the top to the bottom. A 3D near-surface velocity model is then formed using the velocity models at all CMP locations. The tests on synthetic and observed seismic data show that the layer-stripping method can be used to build good near-surface velocity models for static correction, and its computation speed is approximately hundred times faster than that of grid tomography.
基金supported by the National Natural Science Foundation of China (No.41230318)the Natural Science Foundation of Shandong Province (No.ZR2014DM006)+1 种基金the China Postdoctoral Science Foundation (No.2015M582138)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education
文摘The seawater column is typically taken as a homogeneous velocity layer in wide-angle crustal seismic surveys in marine environments. However, heterogeneities in salinity and temperature throughout the seawater layer result insignificant lateral variations in its seismic velocity, especially in deep marine environments. Failure to compensate for these velocity inhomogeneities will introduce significant artifacts in constructing crustal velocity models using seismic tomography. In this study, we conduct numerical experiments to investigate the impact of heterogeneous seismic velocities in seawater on tomographic inversion for crustal velocity models. Experiments that include lateral variation in seawater velocity demonstrated that the modeled crustal velocities were contaminated by artifacts from tomographic inversions when assuming a homogeneous water layer. To suppress such artifacts, we propose two strategies：（1） simultaneous inversion of water velocities and the crustal velocities;（2） layer-stripping inversion during which to first invert for seawater velocity and then correct the travel times before inverting for crustal velocities. The layer-stripping inversion significantly improves the modeling of variation in seawater velocity when preformed with seismic sensors deployed on the ocean bottom and in the water column. Such strategies improve crustal modeling via wide-angle seismic surveys in deep-marine environment.
基金financially supported by the National Natural Science Foundation of China(Nos.51873196 and 51903222)the Australian Research Council(Nos.LP220100278,DP190102992 and FT190100188)+1 种基金the Natural Science Foundation of Zhejiang Province(No.LY21E030001)the“Pioneer”and“Leading Goose”R&D Program of Zhejiang(No.2022C03128).
文摘Fabricating a high-performing thermoset using bio-based flame retardant is critical for the sustain-able development of engineering materials with superior fire safety and robust mechanical properties.Herein,the epoxy(EP)composites with the industrial requirements are manufactured with a novel high-efficient,lignin-based flame retardant named DAL-x,which is fabricated by grafting 9,10-dihydro-9-oxa-10-phosphaze-10-oxide(DOPO)onto lignin.The resulting DAL-x/EP composite exhibits excellent flame retardancy with a desirable UL-94 V-0 rating and a satisfactory limiting oxygen index(LOI)of 29.8%due to the appropriate phosphorus content of DAL-x with adjustable molecular chain structure.More-over,the DAL-x/EP composite shows an unexpected improvement in the elastic modulus(∼36%)and well-preserved strength and ductility compared with those of pure EP.This work offers a feasible strat-egy for creating efficient bio-based flame retardants utilizing industrial waste lignin and preparing high-performance EP composites that meet the demanding requirement of fire retardancy in industries,con-tributing to the circular economy and sustainability.
基金supported by the National Natural Science Foundation of China (Nos.41230318,41204087,and 41304109)the Natural Science Foundation of Shandong Province (No.ZR2014DM006)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China (No.20130132110023) the Key Laboratory of Marine Hydrocarbon Resources and Environmental Geology,Ministry of Land and Resources of China (No.MRE201303)
文摘Clustering earthquakes refer to the seismic events that occur closely with each other in time and space. Because their overlapping waveform records make it difficult to pick the first arrivals, the hypocenters of clustering earthquakes cannot be determined accurately by traveltime location methods. Here we apply a reverse-time imaging （RTI） method to map clustering earthquakes. Taking the advantage of directly using waveforms, the RTI method is capable to map either a single small earthquake or some densely distributed clustering earthquakes beneath a 2-D seismic array. In 3-D case the RTI method is successfully applied to locate the long-offset doublet earthquakes using the data from a set of sparsely distributed surface stations. However, for the same acquisition geometry, the RTI encounters challenges in mapping densely distributed clustering earthquakes. While it is obvious that improving the mapping of clustering earthquakes requires a denser receiver network with wider range of illumination angles, it is necessary to verify the actual resolution of the RTI method with synthetic data. In our study area in the Three Gorges region, our tests in 3-D case suggest that some events beneath the linear aligned sub-arrays have reasonable resolution.
文摘OBJECTIVE： The study was undertaken to explore a bibliometric approach to quantitatively assess the research on detection of monosialoganglioside from 2002 to 2011. DATA RETRIEVAL： A bibliometric analysis based on the publications on Web of Science was performed using key words such as ＂monosialoganglioside＂, ＂colloidal gold＂, ＂high performance liquid chromatography＂ and ＂detection＂. SELECTION CRITERIA： （1） Research articles on the detection of monosialoganglioside; （2） researches on human and animal fundamentals, clinical trials and case reports; （3） article types： article, review, proceedings paper, note, letter, editorial material, discussion, book chapter; （4） Publication year： 2002-2011. Exclusion criteria： （1） unrelated articles; （2） type of articles： correction; （3） articles from following databases： all databases related to social science and arts ＆ humanities in Web of Science were excluded. MAIN OUTCOME MEASURES： （1） distribution of subject areas; （2） number of publications annually; （3） document type and language of publications; （4） distribution of institutions; （5） distribution of output in journals; （6） the number of countries in which the article is published; （7） top cited paper. RESULTS： Overall population stands at 1 880 research articles addressing detection of monosialoganglioside in Web of Science during the study period. Articles （1 599） were the most frequently used document type comprising 85.05%, followed by meeting abstracts, reviews and proceedings papers. The distribution of subject categories showed that monosialoganglioside research covered both clinical and basic science research. The USA, Japan, and Italy were the three most productive countries, and the publication numbers in the USA were highest with 559 papers. The University of Milan, Nagoya University, and Kinki University are the most productive institutions regarding detection of monosialoganglioside. In 559 articles published by Americans, Medical College of Georgia ranked the first with 30 articles, followed by University of Medicine and Dentistry of New Jersey （28 articles）, Cornell University （24 articles） and Johns Hopkins University （24 articles）. In 442 articles published by Japanese, Nagoya University ranked the first with 40 articles, followed by Kinki University （36 articles）, and Dokkyo University （31 articles）. Though the total number of publications by Japanese is smaller than Americans, the top three institutions published more publications than American institutions. There is a markedly increase in the number of publications on the subject detection of monosialoganglioside in 2004, which the peak in the past 10 years. The valley bottom of the subject appeared in 2005. In total, the research is increased with time prolonged. Journal of Neurochemistry, Journal of Biological Chemistry and Journal of Neuroimmunology were core subject journals in monosialoganglioside studies. CONCLUSION： This study highlights the topics in detection of monosialoganglioside research that are being published around the world.
基金Project supported by Fundamental Research Funds for the Central Universities(3072021CF2502)Natural Science Foundation of Heilongjiang Province(LH2020A008)+1 种基金Science and Technology Research Program of Chongqing Education Commission of China(KJQN202001420)National College Student Innovation and Entrepreneurship Training Program(202110217224)。
文摘Suppression of the inner energy dissipation,related to the lattice phonons and inner defects,in lanthanide doped upco nversion luminescent materials remains a formidable challenge.Herein,we reveal an energy cycling strategy capable of suppressing the inner energy dissipation in lanthanide doped upconversion nanocrystals.Yb^(3+)ions were introduced in Er^(3+)heavily doped nanocrystals as an energy reservoir to compete with the inner energy dissipation.The detailed energy cycling processes between Er^(3+)activator and Yb^(3+)reservoir,responsible for the enhancement of Er^(3+)upconversion intensity,are proposed and further verified on the basis of spectral observations.The energy cycling strategy,with unique merits like facile and cost-effective preparation as well as broad scope of application,is highly valuable in lanthanide luminescent nano materials.
基金supported by the National Natural Science Foundation of China (Nos. 41230138, 41074077)
文摘Eariy-arrival waveform tomography （EWT） is one of the most promising techniques for building near-surface velocity model. Based on finite-frequency wave equation, EWT estimates velocities by matching calculated early-arrival waveforms with the observed ones. However, the objective function of EWT can easily converge to local minimum because of the cycle-skipping phenomenon. In order to reduce the cycle-skipping problem, a hybrid-domain early-arrival waveform tomography （HEWT） is proposed in this paper. The forward modeling of HEWT is realized in the time domain where early-arrival waveforms are easier to be selected from seismic data and less memory is needed than they are in the frequency domain. The inversion is implemented in the frequency domain where multi-scale strategy is more convenient to be realized than that in the time domain. Discrete Fourier transformation （DFT） is used to transform the time-domain wavefield to the frequency-domain wavefield. Test results show that HEWT is more competitive than EWT in both accuracy and computational time.
基金The work was sponsored by National Natural Science Foundation of China (NSFC)
文摘A long life election spin resonance (ESR) signal at g=2.0006 was observed in the normal lens epithelium and cortical fibers. During ultraviolet (UV) exposure, a new ESR signal at g = 2.0060 was found in the lens epithelium. But this specific signal was not detected in the lens cortical fibers. This suggested that lens epithelial cells were more susceptible to the free radical formation which was induced by UV light. By means of ESR spin probe oxymetry, the oxygen uptake of lens epithelial cells was meas...
基金supported by the National Natural Science Foundation of China(Grant Nos.62205233,62075151,and 62105234)the Fundamental Research Program of Shanxi Province(Grant No.202103021223041)Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering.
文摘We propose and experimentally demonstrate a long-range chaotic Brillouin optical correlation domain analysis by employing an optimized time-gated scheme and differential denoising configuration,where the number of effective resolving points largely increases to more than one million.The deterioration of the chaotic Brillouin gain spectrum(BGS)and limitation of sensing range owing to the intrinsic noise structure,resulting from the time delay signature(TDS)and nonzero background of chaotic laser,is theoretically analyzed.The optimized time-gated scheme with a higher extinction ratio is used to eliminate the TDS-induced impact.The signal-to-background ratio of the measured BGS is enhanced by the differential denoising scheme to furthest remove the accumulated nonzero noise floor along the fiber,and the pure chaotic BGS is ulteriorly obtained by the Lorentz fit.Ultimately,distributed strain sensing along a 27.54-km fiber with a 2.69-cm spatial resolution is experimentally demonstrated,and the number of effective resolving points is more than 1,020,000.
文摘BACKGROUND： The monosialoganglioside （GM1） is a popular topic of research but the bibliometric analysis of GM1 over the decades in Science Citation Index-Expanded （SCI-E） remains poorly understood. OBJECTIVE： To identify the global research and to improve the understanding of research trends in the GM1 field from 1942 to 2011. DESIGN： A bibliometric study. DATA RETRIEVAL： We performed a bibliometric analysis based on the SCI-E published by the Institute of Scientific Information. INCLUSIVE CRITERIA： Articles closely related to GM1 were included. Exclusive criteria： （1） Articles related to gangliosidosis, disialo-ganglioside, trisialo-ganglioside or ganglioside GQIb. （2） Document types such as meeting abstracts, reviews, proceedings papers, notes, and letters. MAIN OUTCOME MEASURES： （1） Type of publication output; （2） number of author outputs; （3） distribution of output in subject categories; （4） publication distribution of countries; （5） distribution of output in journals, and （6） distribution of citations in each decade. RESULTS： During 1942 to 2011, there were 10 126 papers on GM1 that were added to the SCI. Articles （8 004） were the most frequently used document type comprising 79.0%, followed by meeting abstracts, reviews and proceedings papers. Research on GM1 could be found in the SCI from 1942, it was developed in the 1970s, greatly increased in the 1980s, and reached a peak in the 1990s, and it was slightly decreased in 2000. The distribution of subject categories showed that GM1 research covered both clinical and basic science research. The USA, Japan, and Germany were the three most productive countries, and the publication numbers in the USA were highest in all decades. The Joumal of Biological Chemistry, Journal of Neurochemistry and Biochemistry were core subject journals in GM1 studies in each decade. CONCLUSION： This study highlights the topics in GM1 research that are being published around the world.
基金We appreciate the National Natural Science Foundation of China （No. 20962018, 20862015, 20762009 and 20562011） for supporting this research.
文摘An efficient enantioselective Michael addition of ethyl-2-cyanoacetate and diethyl malonate to α,β-unsaturated ketones catalyzed by a simple chiral Schiff base, and products were obtained in good yields at room temperature.
文摘Helicobacter pylori, the major cause of gastritis, peptic ulcer and gastric cancer, infects half of the world population, but only a few infections lead to serious disease. In order to investigate specific proteins related to the pathogenic difference of this bacterium, comparative proteome analyses of Helicobacter pylori C1 (isolated from patients with gastric cancer) and G1 (isolated from patients with gastritis) were performed using two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). Four proteins (inorganic pyrophosphatase, 3-oxoadipate CoA-transferase subunit B, translation elongation factor, and aldo-keto reductase) were found only in Helicobacter pylori C1, and one protein (alkyl hydroperoxide reductase) was found in G1. Additionally, different isoelectric points (pI) of Hsp60 were observed from the two strains. Then we cloned and sequenced Hsp60 genes from forty-nine Helicobacter pylori isolated from gastric cancer and gastritis. Gene sequencing showed that one C→G single nucleotide polymorphism occurred in the 1399th nucleotide of Hsp60. These results indicate that pathogenic differences exist in various Helicobacter pylori isolated from Chinese patients.
基金The authors are extremely grateful to the National Nature Science Foundation of China for supporting this research （No.20962018, No20862015, No.20762009 and No.20562011）.
文摘A series of novel pyrazoles compounds were synthesized by the reaction of five kinds of substitute α-bromoacetophenone with pyrazole intermediates which was prepared by the reaction of chalcones and thiosemicarbazones. This method has some advantages such as mild reaction condition, easy operation and higher yield. All the compounds were confirmed by elemental analysis, IR and 1H NMR.
文摘We demonstrate a white light fiber source based on Bismuth and Erbium co-doped fiber and a single 830nm laser diode pump. The light spectral intensity from 1100 to 1570nm is over -45dBm, which provide ~40dB dynamic range for an OSA based spectral measurement.
文摘We demonstrate a smart optical fiber sensor unit to realize a multi-parameter sensing, including temperature, curvature and strain or displacement. The sensor unit is composed of a Bragg grating in graded-index multimode fiber and a Fizeau cavity.
基金National Natural Science Foundation of China(Nos.82073459,82373504,and 81602939)Capital’s Funds for Health Improvement and Research(No.2020-4-4087)
文摘Background:Research has indicated that the disease burden of alopecia areata(AA)in China exceeds the global average.Therefore,accurate and updated epidemiological information is crucial for policymakers.In this study,we aimed to comprehensively assess the disease burden of AA in China.Methods:The following four key indicators were utilized:the prevalence of cases;disability-adjusted life-years(DALYs);the age-standardized prevalence rate(ASPR);and the age-standardized DALY rate(ASDR)of AA according to the Global Burden of Disease(GBD)study 2021.We analyzed the epidemiological burden of AA in China during 2021,examined changes between 1990 and 2021,and performed a Bayesian age-period-cohort analysis to predict trends over the course of the next decade(2022-2030).Additionally,a Gaussian process regression model was applied to estimate the relationship between the gross domestic product(GDP)and the ASPR and ASDR of AA at the provincial level between 1992 and 2021.Results:In 2021,the estimated number of patients with AA in China was approximately 3.49 million(95%uncertainty interval[UI],3.37-3.62 million);of these patients,1.20 million(95%UI,1.16-1.25 million)were male and 2.29 million(95%UI,2.20-2.37 million)were female.This large number of patients with AA resulted in a total of 114,431.25 DALYs(95%UI,74,780.27-160,318.96 DALYs).Additionally,the ASPR and ASDR were 224.61 per 100,000 population(95%UI,216.73-232.65 per 100,000 population)and 7.41 per 100,000 population(95%UI,4.85-10.44 per 100,000 population),respectively;both of these rates were higher than the global averages.The most affected demographic groups were young and female individuals 25-39 years of age.Slight regional disparities were observed,with the northern and central regions of China bearing comparatively higher burdens.Between 1990 and 2021,the health loss and disease burden caused by AA in China remained relatively stable.The ASPR and ASDR of AA increased with the GDP when the annual GDP was less than 2 trillion Chinese yuan;however,a downward trend was observed as the GDP surpassed 2 trillion Chinese yuan.A slight upward trend in the disease burden of AA in China is predicted to occur over the next decade.Conclusions:AA continues to be a public health concern in China that shows no signs of declining.Targeted efforts for young individuals and females are necessary because they experience a disproportionately high burden of AA.
