Objective To investigate the indigenous lactobacilli from the vagina of pregnant women and to screen the isolates with antagonistic potential against pathogenic microorganisms. Methods The strains were isolated from p...Objective To investigate the indigenous lactobacilli from the vagina of pregnant women and to screen the isolates with antagonistic potential against pathogenic microorganisms. Methods The strains were isolated from pregnant women＇s vagina and identified using the API50CH system. The ability of the isolates to produce hydrogen peroxide was analyzed semi-quantitatively using the TMB-HRP-MRS agar. The antagonistic effects of the isolates on pathogenic microorganisms were determined with a double layer agar plate. Results One hundred and three lactobacilli strains were isolated from 60 samples of vaginal secretion from healthy pregnant women. Among them, 78 strains could produce hydrogen peroxide, in which 68%, 80%, 80%, and 88% had antagonistic effects against Candida albicans CMCC98001, Staphylococcus aureus CMCC26003, Escherichia coli CMCC44113, and Pseudomonas aeruginosa CMCC10110, respectively. Conclusion The recovery of hydrogen peroxide-producing lactobacilli decreases with the increasing pregnant age and time. The most commonly isolated species from vagina of Chinese pregnant women are Lactobacillus acidophilus and Lactobacillus crispatus. Most of L. acidophilus and L. crispatus produce a high H2O2 level.展开更多
Excess accumulation of white adipose tissue(WAT) causes obesity which is an imbalance between energy intake and energy expenditure. Obesity is a serious concern because it has been the leading causes of death worldwid...Excess accumulation of white adipose tissue(WAT) causes obesity which is an imbalance between energy intake and energy expenditure. Obesity is a serious concern because it has been the leading causes of death worldwide, including diabetes, stroke,heart disease and cancer. Therefore, uncovering the mechanism of obesity and discovering anti-obesity drugs are crucial to prevent obesity and its complications. Browning, inducing white adipose tissue to brown or beige(brite) fat which is brown-like fat emerging in WAT, becomes an appealing therapeutic strategy for obesity and metabolic disorders. Due to lack of efficacy or intolerable side-effects, the clinical trials that promote brown adipose tissue(BAT) thermogenesis and browning of WAT have not been successful in humans. Obviously, more specific means still need to be developed to activate browning of white adipose tissue. In this review, we summarized seven kinds of natural products(alkaloids, flavonoids, terpenoids, long chain fatty acids, phenolic acids, else and extract) promoting white adipose tissue browning which can ameliorate the metabolic disorders, including obesity, dislipidemia, insulin resistance and diabetes. Since natural products are important drug sources and the browning property plays a significant role in not only obesity treatment but also in type 2 diabetes(T2 DM) improvement, natural products of inducing browning may be an irreplaceable drug discovery orientation for obesity, diabetes and even other metabolic disorders.展开更多
Inspired by the gradient structure of the nature,two gradient lattice structures,i.e.,unidirectional gradient lattice(UGL)and bidirectional gradient lattice(BGL),are proposed based on the body-centered cubic(BCC)latti...Inspired by the gradient structure of the nature,two gradient lattice structures,i.e.,unidirectional gradient lattice(UGL)and bidirectional gradient lattice(BGL),are proposed based on the body-centered cubic(BCC)lattice to obtain specially designed mechanical behaviors,such as load-bearing and energy absorption capacities.First,a theoretical model is proposed to predict the initial stiffness of the gradient lattice structure under compressive loading,and validated against quasi-static compression tests and finite element models(FEMs).The deformation and failure mechanisms of the two structures are further studied based on experiments and simulations.The UGL structure exhibits a layer-by-layer failure mode,which avoids structure-wise shear failure in uniform structures.The BGL structure presents a symmetry deformation pattern,and the failure initiates at the weakest part.Finally,the energy absorption behaviors are also discussed.This study demonstrates the potential application of gradient lattice structures in load-transfer-path modification and energy absorption by topology design.展开更多
By analyzing the development and industrialization of China’s manufacturing industry since reform and opening-up,this paper proposes China has played three roles in economic globalization-as an in-depth participant i...By analyzing the development and industrialization of China’s manufacturing industry since reform and opening-up,this paper proposes China has played three roles in economic globalization-as an in-depth participant in specialization of the global manufacturing value chain,as an active facilitator of global inclusive and sustainable industrialization,and as a cooperative innovator in the new industrial revolution.It is significant for comprehensively understanding the role of China in economic globalization.展开更多
We report a robust method of directly stabilizing a grating feedback diode laser to an arbitrary frequency in a large range. The error signal, induced from the difference between the frequency measured by a wavelength...We report a robust method of directly stabilizing a grating feedback diode laser to an arbitrary frequency in a large range. The error signal, induced from the difference between the frequency measured by a wavelength meter and the preset target frequency, is fed back to the piezoelectric transducer module of the diode laser via a sound card in the computer. A visual Labview procedure is developed to realize a feedback system. In our experiment the frequency drift of the diode laser is reduced to 8 MHz within 25 min. The robust scheme can be adapted to realize the arbitrary frequency stabilization for many other kinds of lasers.展开更多
The stress corrosion cracking(SCC)behavior of a 1900 MPa-grade ultra-high-strength stainless steel in 3.5 wt.% NaCl solution was investigated by X-ray diffractometer,scanning electron microscopy,electron back-scattere...The stress corrosion cracking(SCC)behavior of a 1900 MPa-grade ultra-high-strength stainless steel in 3.5 wt.% NaCl solution was investigated by X-ray diffractometer,scanning electron microscopy,electron back-scattered diffraction,X-ray photoelectron spectroscopy,and potentiodynamic polarization curves.The results showed that USS122G stel has good SCC resistance,and the critical stress intensiy factor(K_(iscc))of USS122G steel was about 68.906 MPa m^(1/2) and Kiscc/K_(ic)=0.76(K_(ic) is plane strain fracture toughness).The existence of film-like austenite along the lath martensite boundary and the protective effect of thecc passivation flm were the main factors for its high Kiscc.Among them,the main components of the passivation film on the surface of USS122G steel were Cr_(2)O_(3),Cr(OH)_(3),FeOOH,and Ni(OH)_(2).The fracture morphology of SCC zone was intergranular and transgranular.Through the slow and fast scanning rate polarization curve test results,it can be concluded that SCC mechanism of USS122G steel in 3.5 wt.%NaCl solution at the open-circuit potential was a mixed mechanism involving hydrogen embritlement and anodic dissolution.展开更多
Alpine grassland occupies two-thirds of the Qinghai-Tibetan Plateau (QTP). It is vital to project changes of this vulnerable ecosystem under different climate change scenarios before taking any mitigation or adaptatio...Alpine grassland occupies two-thirds of the Qinghai-Tibetan Plateau (QTP). It is vital to project changes of this vulnerable ecosystem under different climate change scenarios before taking any mitigation or adaptation measures. In this study, we used a process-based ecosystem model, driven with output from global circulation models under different Representative Concentration Pathways (RCPs), to project the carbon dynamics of alpine grassland. The results showed the following: 1) Vegetation carbon (C) on the QTP increased by 22—38 gC m^-2 during periods of 1.5 and 2 ℃ warming under different RCPs when compared to the baseline period (1981—2006), while soil C increased by 85—122 gC m^-2. 2) The increases of vegetation C and soil C at the period of 1.5 ℃ warming were about 15 gC m^-2 and 40 gC m^-2 smaller than those at the period of 2 ℃ warming, respectively;increase of C was greater for alpine meadow than for alpine steppe. 3) Precipitation, radiation, and permafrost changed significantly and showed heterogeneous spatial patterns, and caused heterogeneous response of C dynamics. For alpine meadow in regions transformed from permafrost to seasonally frozen soil with medium annual precipitation (200—400 mm), vegetation C and net primary production decreased by 18.7 gC m-2 and 3.1 gC m^-2 per year during 2 °C warming under RCP 4.5, respectively. This decrease can be attributed to the disappearing impermeable permafrost. Different from previous studies that indicated an unfavorable response of alpine grassland to climate warming, this study showed a relatively favorable response, which is mainly attributed to C 0 2 fertilization.展开更多
Rare Earths (RE) for agriculture is a very typical application and has already brought good economic benefit to Chinese agriculture and farmers.In this paper, the origin, development, status and the future of RE for a...Rare Earths (RE) for agriculture is a very typical application and has already brought good economic benefit to Chinese agriculture and farmers.In this paper, the origin, development, status and the future of RE for agriculture in China were discussed.Firstly, through the researches of RE in the fields of physiological activity, physiological and biochemical mechanism, sanitation toxicology and environment security in 1980's, RE has been extended more widely in agriculture, such as crops, vegetables, forest, wood grass and stock breeding, such as cattle, fish and chicken.Secondly, with using of new techniques that were developed in the "State Ninth Five-Year Plan", the utilization area of RE was expanded to broad agricultural space, such as sunlight converting plastic film, RE fertilizer, RE drought resistant and RE water saving materials and new RE top dressing fertilizer.Thirdly, with the development of the nanometer materials, the techniques and process of nanometer RE materials were focused.Around these kinds of materials, the new seed cover matters, new seed mixed matter and new nanometer fertilizer will appear in the near future, and will produce many updated techniques and improve a new round RE application in agriculture.展开更多
The adsorption kinetics and equilibrium of H<sub>2</sub>PtCl<sub>6</sub> on various types of alumina were studied,and IRSand DRS were used to characterize these supports before and after impreg...The adsorption kinetics and equilibrium of H<sub>2</sub>PtCl<sub>6</sub> on various types of alumina were studied,and IRSand DRS were used to characterize these supports before and after impregnating with H<sub>2</sub>PtCl<sub>6</sub> solution.Thedata indicated that the uptake of H<sub>2</sub>PtCl<sub>6</sub> on supports strongly depends on the Lewis acidity of alumina andthat the adsorption rate is controlled by pore diffusion for supports of high adsorption capacity.Relationshipbetween uptake and acidity is interpreted in terms of active hydroxyl groups on alumina.展开更多
Heterogeneous catalysis is of tremendous importance to modern industries. Exposed atoms of heterogeneous catalysts are heavily involved in surface processes such as the adsorption, activation, diffusion and reaction o...Heterogeneous catalysis is of tremendous importance to modern industries. Exposed atoms of heterogeneous catalysts are heavily involved in surface processes such as the adsorption, activation, diffusion and reaction of substrate molecules. Surfaces of metal or metal oxide based catalysts are usually taken as hard templates that only undergo limited relaxation during catalytic reactions, especially in theoretical simulations. In this work, by using genetic algorithm (GA) aided density functional theory (DFT) calculations, we studied the surface processes involved in CO oxidation on the Au(100) surface. The use of GA greatly improves the capacity of DFT calculations in locating the potential energy surface (PES) of the surface reactions, and surprisingly, it has been found that the Au(100) surface can undergo drastic reconstruction under the influence of O adsorption and the adapted partially oxidized Au surface exhibits unique activities for subsequent adsorptions and reactions. This work depicts the kinetic nature of the Au (100) surface in its catalyzed reactions and also significantly expands our understanding of how surface atoms act in heterogeneous catalysis.展开更多
Objective This study aimed to analyze the temporal trends and characteristics associated with waist circumference(WC)among elderly Chinese people.Methods We used data from 3,096 adults≥65 years who participated in th...Objective This study aimed to analyze the temporal trends and characteristics associated with waist circumference(WC)among elderly Chinese people.Methods We used data from 3,096 adults≥65 years who participated in the China Health and Nutrition Survey(CHNS),an ongoing cohort study,between 1993 and 2015.We used longitudinal quantile regression models to explore the temporal trends and characteristics associated with WC.Results WC increased gradually among the elderly Chinese population during the survey.The WC curves shifted to the right with wider distributions and lower peaks in men and women.All WC percentile curves shifted upward with similar growth rates in the 25th,50th,and 75th percentiles.The WC means increased from 78 cm to 86 cm during the 22 years of our study.WC significantly increased with age and body mass index and decreased with physical activity(PA).These associations were stronger in the higher percentiles than in the lower percentiles.Conclusions WC is rising among Chinese adults≥65 years.Factors affecting WC in elderly people may have different effects on different percentiles of the WC distribution,and PA was the most important protective factor in the higher percentiles of the WC distribution.Thus,different interventional strategies are needed.展开更多
1.Objectives The study of the paleo-reservoir is of great significance for oil and gas exploration.Firstly,the existence of paleoreservoirs can reflect there has been hydrocarbon accumulation process in this area,wher...1.Objectives The study of the paleo-reservoir is of great significance for oil and gas exploration.Firstly,the existence of paleoreservoirs can reflect there has been hydrocarbon accumulation process in this area,where there once was the advantageous condition with source-reservoir-cap combination;secondly,it can indicate that this area has certain resource potential.The purpose of this research is: through the study of the paleo-reservoir of CSDP-2 well in the Laoshan uplift of the South Yellow Sea Basin,which is a scientific investigation well,it can provide geological basis for marine oil and gas exploration of the Mesozoic and Paleozoic in the Laoshan uplift of the South Yellow Sea Basin,and at the same time can provide important information for future exploration target selection.展开更多
The vertical distribution and exchange mechanisms of soil organic and inorganic carbon(SOC,SIC)play an important role in assessing carbon(C)cycling and budgets.However,the impact of land use through time for deep soil...The vertical distribution and exchange mechanisms of soil organic and inorganic carbon(SOC,SIC)play an important role in assessing carbon(C)cycling and budgets.However,the impact of land use through time for deep soil C(below 100 cm)is not well known.To investigate deep C storage under different land uses and evaluate how it changes with time,we collected soil samples to a depth of 500 cm in a soil profile in the Gutun watershed on the Chinese Loess Plateau(CLP);and determined SOC,SIC,and bulk density.The magnitude of SOC stocks in the 0-500 cm depth range fell into the following ranking:shrubland(17.2 kg m-2)>grassland(16.3 kg m-2)>forestland(15.2 kg m-2)>cropland(14.1 kg m 2)>gully land(6.4 kg m 2).The ranking for SIC stocks were:grassland(104.1 kg m^2)>forestland(96.2 kg m^2)>shrubland(90.6 kg m-2)>cropland(82.4 kg m 2)>gully land(50.3 kg m-2).Respective SOC and SIC stocks were at least 1.6-and 2.1-fold higher within the 100-500 cm depth range,as compared to the 0-100 cm depth range.Overall SOC and SIC stocks decreased significantly from the 5th to the 15th year of cultivation in croplands,and generally increased up to the 70th year.Both SOC and SIC stocks showed a turning point at 15 years cultivation,which should be considered when evaluating soil C sequestration.Estimates of C stocks greatly depends on soil sampling depth,and understanding the influences of land use and time will improve soil productivity and conservation in regions with deep soils.展开更多
Polycyclic aromatic hydrocarbons(PAHs)in indoor dust are one of the common exposure sources for children worldwide.The aim of this study is to explore PAHs pollution status in indoor dust and estimate health risk on C...Polycyclic aromatic hydrocarbons(PAHs)in indoor dust are one of the common exposure sources for children worldwide.The aim of this study is to explore PAHs pollution status in indoor dust and estimate health risk on Chinese children with big data.Weighted average concentration was used to analyze source and characterization of PAHs in indoor dust based on peer=reviewed literature.According to specific inclusion crteria,17 studies were included finally to analyze weighted average concentration.The national average concentration of ∑_(16)PAHs was approximately 25.696 ug/g.The highest concentration of ∑_(16)AHs was in Shanxi(2111.667 ug/g),and the lowest was in Hong Kong(1.505 μg/g).The concentrations in Shanxi and Guangdong were higher than national level and the over standard rate was 18.18%.The concentrations of individual PAHs varied greatly across the country,and Flu in Shanxi was the highest(189.400 μg/g).The sources of PAHs varied in different regions and combustion processes played a leading role.PAHs exposure through ingestion and dermal contact was more carcinogenic than inhalation.The incremental lifetime cancer risk model indicated that children lived in Shanxi were found in the highest health risk coupled with the highest BaPE concentration(54.074μg/g).Although PAHs concentrations of indoor dust showed a downward trend from 2005 to 2018,indoor environmental sanitation should be improved with multidisciplinary efforts.Health standard should be possibly established to minimize children exposure to PAHs in indoor dust in China.展开更多
Objective:To evaluate the efficacy and safety of percutaneous core needle biopsy(PCNB)using ultrasound(US)-guided and contrast-enhanced ultrasound(CEUS)-guided procedures for anterior mediastinal masses(AMMs).Methods:...Objective:To evaluate the efficacy and safety of percutaneous core needle biopsy(PCNB)using ultrasound(US)-guided and contrast-enhanced ultrasound(CEUS)-guided procedures for anterior mediastinal masses(AMMs).Methods:In total,284 consecutive patients(166 men,118 women;mean age,43.0±18.4 years)who underwent PCNB for AMMs were enrolled.Patients were divided into the US-guided group(n=133)and the CEUS-guided group(n=151).PCNB was performed using a core needle(16-gauge or 18-gauge).Internal necrosis,diagnostic yield,and diagnostic accuracy were compared between the two groups.Results:The predominant final diagnosis of the cases in this study was thymoma(29.7%),lymphoma(20.5%),thymic carcinoma(13.3%),and germ cell tumour(13.3%),respectively.There was no significant difference in patient age,sex,number of percutaneous biopsies,or display rate of internal necrosis on conventional US between the two groups.The rate of internal necrosis of the lesions was significantly higher after contrast agent injection(72.2%vs.41.7%;P<0.001).The CEUS-guided group had a higher diagnostic yield than the US-guided group(100%vs.89.5%,P<0.001).There was no significant difference between the diagnostic accuracy of the CEUSguided and US-guided groups(97.3%vs.97.4%;P=1.000).None of the patients experienced adverse reactions or complications after US-guided or CEUS-guided PCNB.Conclusions:CEUS-guided PCNB can improve the diagnostic yield by optimizing the biopsy procedure.展开更多
AIM: To study the expression of HBV enhancer Ⅱ by transcription factor COUP-TF1. METHODS: In order to study the regulation of HBV variants in the vicinity of the NRRE we cloned luciferase constructs containing the HB...AIM: To study the expression of HBV enhancer Ⅱ by transcription factor COUP-TF1. METHODS: In order to study the regulation of HBV variants in the vicinity of the NRRE we cloned luciferase constructs containing the HBV enhancer Ⅱ from variants and from HBV genotypes A and D and cotransfected them together with expression vectors for COUP-TF1 into HepG2 cells. RESULTS: Our fi ndings show that enhancer Ⅱ of HBV genotype A is also repressed by COUP-TF1. In contrast, two different enhancer Ⅱ constructs of HBV genotype D were activated by COUP-TF1. The activation was independent of the NRRE because a natural variant with a deletion of nt 1763-1770 was still activated by COUP- TF1. CONCLUSION: Regulation of transcription of the HBV genome seems to differ among HBV genomes derived from different genotypes. These differences in transcriptional control among HBV genotypes may be the molecular basis for differences in the clinical course among HBV genotypes.展开更多
In this work,a blue emitter with a 3 D rigid structure composed of multiple spirobifluorene(3-Spiro) has been synthesized and characterized.Through a detailed study of the electrochemical and photophysical properties ...In this work,a blue emitter with a 3 D rigid structure composed of multiple spirobifluorene(3-Spiro) has been synthesized and characterized.Through a detailed study of the electrochemical and photophysical properties of 3-Spiro,we have evidenced that 3-Spiro can be applied as an active component of organic light-emitting diodes(OLEDs).The device with 5% doping rate of 4 CzPNPh exhibits high external quantum efficiency(EQE) of 11%,which proves the potential of 3 D rigid structure emitters for OLEDs.展开更多
The objective of this study is to provide scientific guidance for optimizing agricultural field nitrogen management that is based on the evaluation of current nitrogen application practice in Jiangsu Province, China, ...The objective of this study is to provide scientific guidance for optimizing agricultural field nitrogen management that is based on the evaluation of current nitrogen application practice in Jiangsu Province, China, in 2000. The agricultural nitrogen models, consist of the soil mineralization model, the organic manure nitrogen releasing model, and the nitrogenous fertilizer use efficiency model. These models combined with the geographic information system technique were used to describe the spatial variability of nitrogen released from soil and organic manure and to identify its contributing factors. The comparison of the nitrogen fertilizer amount required by croplands, which was simulated by the models with the actual nitrogen fertilizer applied rate, was used to evaluate the current nitrogen application. The results showed that nitrogen was excessively applied in 71.8% croplands, given that the actual crop yield was desired. The excessive nitrogen amounted to 760 kiloton, accounting for 41.5% of the total nitrogen applied. Given that the actual highest yield was desired, nitrogen was reduced in 64.3% croplands. The total shortage of nitrogen was about 800 kiloton. Low use efficiency of nitrogen fertilizer was found in Taihu Lake area, Nanjing-Zhenjiang hilly area, and Xuzhou area, whereas the east beach area of Jiangsu showed an obvious deficiency of nitrogen fertilizer inputs. A balance of nitrogen fertilizer in Jiangsu croplands between excessive and deficient application areas would greatly benefit economic and environmental advantages.展开更多
基金the chinese national 973 project (NKBRSF G1998030609 )863 Project (2001AA144030)work reportecd herein has been supported in part by the national science foundation under (ccr-0201772 , int-9722919) and in part by t
基金China Scholarship Council (2003836007)863 Program of China (2008AA10Z337)973 Program of China (2005DKA21202-1)
文摘Objective To investigate the indigenous lactobacilli from the vagina of pregnant women and to screen the isolates with antagonistic potential against pathogenic microorganisms. Methods The strains were isolated from pregnant women＇s vagina and identified using the API50CH system. The ability of the isolates to produce hydrogen peroxide was analyzed semi-quantitatively using the TMB-HRP-MRS agar. The antagonistic effects of the isolates on pathogenic microorganisms were determined with a double layer agar plate. Results One hundred and three lactobacilli strains were isolated from 60 samples of vaginal secretion from healthy pregnant women. Among them, 78 strains could produce hydrogen peroxide, in which 68%, 80%, 80%, and 88% had antagonistic effects against Candida albicans CMCC98001, Staphylococcus aureus CMCC26003, Escherichia coli CMCC44113, and Pseudomonas aeruginosa CMCC10110, respectively. Conclusion The recovery of hydrogen peroxide-producing lactobacilli decreases with the increasing pregnant age and time. The most commonly isolated species from vagina of Chinese pregnant women are Lactobacillus acidophilus and Lactobacillus crispatus. Most of L. acidophilus and L. crispatus produce a high H2O2 level.
基金supported by the National Natural Science Foundation of China (No. 81770847)the Drug Innovation Major Project (No. 2018ZX09711001-003-005)CAMS Innovation Fund for Medical Sciences (No. 2017-I2M-1-010)。
文摘Excess accumulation of white adipose tissue(WAT) causes obesity which is an imbalance between energy intake and energy expenditure. Obesity is a serious concern because it has been the leading causes of death worldwide, including diabetes, stroke,heart disease and cancer. Therefore, uncovering the mechanism of obesity and discovering anti-obesity drugs are crucial to prevent obesity and its complications. Browning, inducing white adipose tissue to brown or beige(brite) fat which is brown-like fat emerging in WAT, becomes an appealing therapeutic strategy for obesity and metabolic disorders. Due to lack of efficacy or intolerable side-effects, the clinical trials that promote brown adipose tissue(BAT) thermogenesis and browning of WAT have not been successful in humans. Obviously, more specific means still need to be developed to activate browning of white adipose tissue. In this review, we summarized seven kinds of natural products(alkaloids, flavonoids, terpenoids, long chain fatty acids, phenolic acids, else and extract) promoting white adipose tissue browning which can ameliorate the metabolic disorders, including obesity, dislipidemia, insulin resistance and diabetes. Since natural products are important drug sources and the browning property plays a significant role in not only obesity treatment but also in type 2 diabetes(T2 DM) improvement, natural products of inducing browning may be an irreplaceable drug discovery orientation for obesity, diabetes and even other metabolic disorders.
基金the National Natural Science Foundation of China(Grant Nos.11972049 and 12002050)National Key Laboratory Foundation of Science and Technology on Materials under Shock and Im-pact(Grant No.6142902200401)Opening Fund of State Key Laboratory of Nonlinear Mechanics.
文摘Inspired by the gradient structure of the nature,two gradient lattice structures,i.e.,unidirectional gradient lattice(UGL)and bidirectional gradient lattice(BGL),are proposed based on the body-centered cubic(BCC)lattice to obtain specially designed mechanical behaviors,such as load-bearing and energy absorption capacities.First,a theoretical model is proposed to predict the initial stiffness of the gradient lattice structure under compressive loading,and validated against quasi-static compression tests and finite element models(FEMs).The deformation and failure mechanisms of the two structures are further studied based on experiments and simulations.The UGL structure exhibits a layer-by-layer failure mode,which avoids structure-wise shear failure in uniform structures.The BGL structure presents a symmetry deformation pattern,and the failure initiates at the weakest part.Finally,the energy absorption behaviors are also discussed.This study demonstrates the potential application of gradient lattice structures in load-transfer-path modification and energy absorption by topology design.
文摘By analyzing the development and industrialization of China’s manufacturing industry since reform and opening-up,this paper proposes China has played three roles in economic globalization-as an in-depth participant in specialization of the global manufacturing value chain,as an active facilitator of global inclusive and sustainable industrialization,and as a cooperative innovator in the new industrial revolution.It is significant for comprehensively understanding the role of China in economic globalization.
基金Project supported by the National Basic Research Program of China(Grant No.2012CB921603)the Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China(Grant No.IRT13076)+4 种基金the Major Research Plan of the National Natural Science Foundation of China(Grant No.91436108)the National Natural Science Foundation of China(Grant Nos.61378014,61308023,61378015,and 11434007)the Fund for Fostering Talents in Basic Science of the National Natural Science Foundation of China(Grant No.J1103210)the New Teacher Fund of the Ministry of Education of China(Grant No.20131401120012)the Natural Science Foundation for Young Scientists of Shanxi Province,China(Grant No.2013021005-1)
文摘We report a robust method of directly stabilizing a grating feedback diode laser to an arbitrary frequency in a large range. The error signal, induced from the difference between the frequency measured by a wavelength meter and the preset target frequency, is fed back to the piezoelectric transducer module of the diode laser via a sound card in the computer. A visual Labview procedure is developed to realize a feedback system. In our experiment the frequency drift of the diode laser is reduced to 8 MHz within 25 min. The robust scheme can be adapted to realize the arbitrary frequency stabilization for many other kinds of lasers.
基金support from the National Key Research and Development Program of China(2016YFB0300104).
文摘The stress corrosion cracking(SCC)behavior of a 1900 MPa-grade ultra-high-strength stainless steel in 3.5 wt.% NaCl solution was investigated by X-ray diffractometer,scanning electron microscopy,electron back-scattered diffraction,X-ray photoelectron spectroscopy,and potentiodynamic polarization curves.The results showed that USS122G stel has good SCC resistance,and the critical stress intensiy factor(K_(iscc))of USS122G steel was about 68.906 MPa m^(1/2) and Kiscc/K_(ic)=0.76(K_(ic) is plane strain fracture toughness).The existence of film-like austenite along the lath martensite boundary and the protective effect of thecc passivation flm were the main factors for its high Kiscc.Among them,the main components of the passivation film on the surface of USS122G steel were Cr_(2)O_(3),Cr(OH)_(3),FeOOH,and Ni(OH)_(2).The fracture morphology of SCC zone was intergranular and transgranular.Through the slow and fast scanning rate polarization curve test results,it can be concluded that SCC mechanism of USS122G steel in 3.5 wt.%NaCl solution at the open-circuit potential was a mixed mechanism involving hydrogen embritlement and anodic dissolution.
基金This study was jointly supported through grants provided as part of the Na tional Natural Science Foundation of China (41690142, 41730751)the State Key Laboratory of Cryospheric Science (SKLCS-ZZ-2-2018).
文摘Alpine grassland occupies two-thirds of the Qinghai-Tibetan Plateau (QTP). It is vital to project changes of this vulnerable ecosystem under different climate change scenarios before taking any mitigation or adaptation measures. In this study, we used a process-based ecosystem model, driven with output from global circulation models under different Representative Concentration Pathways (RCPs), to project the carbon dynamics of alpine grassland. The results showed the following: 1) Vegetation carbon (C) on the QTP increased by 22—38 gC m^-2 during periods of 1.5 and 2 ℃ warming under different RCPs when compared to the baseline period (1981—2006), while soil C increased by 85—122 gC m^-2. 2) The increases of vegetation C and soil C at the period of 1.5 ℃ warming were about 15 gC m^-2 and 40 gC m^-2 smaller than those at the period of 2 ℃ warming, respectively;increase of C was greater for alpine meadow than for alpine steppe. 3) Precipitation, radiation, and permafrost changed significantly and showed heterogeneous spatial patterns, and caused heterogeneous response of C dynamics. For alpine meadow in regions transformed from permafrost to seasonally frozen soil with medium annual precipitation (200—400 mm), vegetation C and net primary production decreased by 18.7 gC m-2 and 3.1 gC m^-2 per year during 2 °C warming under RCP 4.5, respectively. This decrease can be attributed to the disappearing impermeable permafrost. Different from previous studies that indicated an unfavorable response of alpine grassland to climate warming, this study showed a relatively favorable response, which is mainly attributed to C 0 2 fertilization.
文摘Rare Earths (RE) for agriculture is a very typical application and has already brought good economic benefit to Chinese agriculture and farmers.In this paper, the origin, development, status and the future of RE for agriculture in China were discussed.Firstly, through the researches of RE in the fields of physiological activity, physiological and biochemical mechanism, sanitation toxicology and environment security in 1980's, RE has been extended more widely in agriculture, such as crops, vegetables, forest, wood grass and stock breeding, such as cattle, fish and chicken.Secondly, with using of new techniques that were developed in the "State Ninth Five-Year Plan", the utilization area of RE was expanded to broad agricultural space, such as sunlight converting plastic film, RE fertilizer, RE drought resistant and RE water saving materials and new RE top dressing fertilizer.Thirdly, with the development of the nanometer materials, the techniques and process of nanometer RE materials were focused.Around these kinds of materials, the new seed cover matters, new seed mixed matter and new nanometer fertilizer will appear in the near future, and will produce many updated techniques and improve a new round RE application in agriculture.
文摘The adsorption kinetics and equilibrium of H<sub>2</sub>PtCl<sub>6</sub> on various types of alumina were studied,and IRSand DRS were used to characterize these supports before and after impregnating with H<sub>2</sub>PtCl<sub>6</sub> solution.Thedata indicated that the uptake of H<sub>2</sub>PtCl<sub>6</sub> on supports strongly depends on the Lewis acidity of alumina andthat the adsorption rate is controlled by pore diffusion for supports of high adsorption capacity.Relationshipbetween uptake and acidity is interpreted in terms of active hydroxyl groups on alumina.
基金supported by National Key R&D Program of China(No. 2018YFA0208602)National Natural Science Foundation of China(Nos. 21421004, 21825301, 21573067, 91545103)Program of Shanghai Academic Research Leader (No. 17XD1401400)
文摘Heterogeneous catalysis is of tremendous importance to modern industries. Exposed atoms of heterogeneous catalysts are heavily involved in surface processes such as the adsorption, activation, diffusion and reaction of substrate molecules. Surfaces of metal or metal oxide based catalysts are usually taken as hard templates that only undergo limited relaxation during catalytic reactions, especially in theoretical simulations. In this work, by using genetic algorithm (GA) aided density functional theory (DFT) calculations, we studied the surface processes involved in CO oxidation on the Au(100) surface. The use of GA greatly improves the capacity of DFT calculations in locating the potential energy surface (PES) of the surface reactions, and surprisingly, it has been found that the Au(100) surface can undergo drastic reconstruction under the influence of O adsorption and the adapted partially oxidized Au surface exhibits unique activities for subsequent adsorptions and reactions. This work depicts the kinetic nature of the Au (100) surface in its catalyzed reactions and also significantly expands our understanding of how surface atoms act in heterogeneous catalysis.
基金Nutrition and Health, Chinese Center for Disease Control and Prevention, Carolina Population Center, the University of North Carolina at Chapel Hill [5 R24 HD050924]the National Institutes of Health [R01-HD30880, DK056350, R24 HD050924, and R01-HD38700]+1 种基金the Chinese Institute of Food Science and Technology [2020-09]the National Natural Science Foundation of China [No.82103848].
文摘Objective This study aimed to analyze the temporal trends and characteristics associated with waist circumference(WC)among elderly Chinese people.Methods We used data from 3,096 adults≥65 years who participated in the China Health and Nutrition Survey(CHNS),an ongoing cohort study,between 1993 and 2015.We used longitudinal quantile regression models to explore the temporal trends and characteristics associated with WC.Results WC increased gradually among the elderly Chinese population during the survey.The WC curves shifted to the right with wider distributions and lower peaks in men and women.All WC percentile curves shifted upward with similar growth rates in the 25th,50th,and 75th percentiles.The WC means increased from 78 cm to 86 cm during the 22 years of our study.WC significantly increased with age and body mass index and decreased with physical activity(PA).These associations were stronger in the higher percentiles than in the lower percentiles.Conclusions WC is rising among Chinese adults≥65 years.Factors affecting WC in elderly people may have different effects on different percentiles of the WC distribution,and PA was the most important protective factor in the higher percentiles of the WC distribution.Thus,different interventional strategies are needed.
文摘1.Objectives The study of the paleo-reservoir is of great significance for oil and gas exploration.Firstly,the existence of paleoreservoirs can reflect there has been hydrocarbon accumulation process in this area,where there once was the advantageous condition with source-reservoir-cap combination;secondly,it can indicate that this area has certain resource potential.The purpose of this research is: through the study of the paleo-reservoir of CSDP-2 well in the Laoshan uplift of the South Yellow Sea Basin,which is a scientific investigation well,it can provide geological basis for marine oil and gas exploration of the Mesozoic and Paleozoic in the Laoshan uplift of the South Yellow Sea Basin,and at the same time can provide important information for future exploration target selection.
基金The Strategic Priority Research Program of the Chinese Academy of Sciences,NO.XDB 40000000National Natural Science Foundation of China,No.41730108,No.41773141,No.41573136,No.41991252National Research Program for Key Issues in Air Pollution Control,No.DQGGO 105-02。
文摘The vertical distribution and exchange mechanisms of soil organic and inorganic carbon(SOC,SIC)play an important role in assessing carbon(C)cycling and budgets.However,the impact of land use through time for deep soil C(below 100 cm)is not well known.To investigate deep C storage under different land uses and evaluate how it changes with time,we collected soil samples to a depth of 500 cm in a soil profile in the Gutun watershed on the Chinese Loess Plateau(CLP);and determined SOC,SIC,and bulk density.The magnitude of SOC stocks in the 0-500 cm depth range fell into the following ranking:shrubland(17.2 kg m-2)>grassland(16.3 kg m-2)>forestland(15.2 kg m-2)>cropland(14.1 kg m 2)>gully land(6.4 kg m 2).The ranking for SIC stocks were:grassland(104.1 kg m^2)>forestland(96.2 kg m^2)>shrubland(90.6 kg m-2)>cropland(82.4 kg m 2)>gully land(50.3 kg m-2).Respective SOC and SIC stocks were at least 1.6-and 2.1-fold higher within the 100-500 cm depth range,as compared to the 0-100 cm depth range.Overall SOC and SIC stocks decreased significantly from the 5th to the 15th year of cultivation in croplands,and generally increased up to the 70th year.Both SOC and SIC stocks showed a turning point at 15 years cultivation,which should be considered when evaluating soil C sequestration.Estimates of C stocks greatly depends on soil sampling depth,and understanding the influences of land use and time will improve soil productivity and conservation in regions with deep soils.
基金supported by the National Natural Science Foundation of China(No.21976169)the Natural Science Foundation of Beijing,China(No.8182055)the Opening Fund of State Key Laboratory of Building Safety and Built Environment,China(No.BSBE2017-09)。
文摘Polycyclic aromatic hydrocarbons(PAHs)in indoor dust are one of the common exposure sources for children worldwide.The aim of this study is to explore PAHs pollution status in indoor dust and estimate health risk on Chinese children with big data.Weighted average concentration was used to analyze source and characterization of PAHs in indoor dust based on peer=reviewed literature.According to specific inclusion crteria,17 studies were included finally to analyze weighted average concentration.The national average concentration of ∑_(16)PAHs was approximately 25.696 ug/g.The highest concentration of ∑_(16)AHs was in Shanxi(2111.667 ug/g),and the lowest was in Hong Kong(1.505 μg/g).The concentrations in Shanxi and Guangdong were higher than national level and the over standard rate was 18.18%.The concentrations of individual PAHs varied greatly across the country,and Flu in Shanxi was the highest(189.400 μg/g).The sources of PAHs varied in different regions and combustion processes played a leading role.PAHs exposure through ingestion and dermal contact was more carcinogenic than inhalation.The incremental lifetime cancer risk model indicated that children lived in Shanxi were found in the highest health risk coupled with the highest BaPE concentration(54.074μg/g).Although PAHs concentrations of indoor dust showed a downward trend from 2005 to 2018,indoor environmental sanitation should be improved with multidisciplinary efforts.Health standard should be possibly established to minimize children exposure to PAHs in indoor dust in China.
基金supported by the Natural Scienceof Shanghai“Science and Technology Innovation Action Plan”(Grant No.20ZR1452800)Clinical Research Plan of SHDC(Grant No.SHDC2020CR1031B)Shanghai Municipal Key Clinical Specialty of China(Grant No.shslczdzk03501)。
文摘Objective:To evaluate the efficacy and safety of percutaneous core needle biopsy(PCNB)using ultrasound(US)-guided and contrast-enhanced ultrasound(CEUS)-guided procedures for anterior mediastinal masses(AMMs).Methods:In total,284 consecutive patients(166 men,118 women;mean age,43.0±18.4 years)who underwent PCNB for AMMs were enrolled.Patients were divided into the US-guided group(n=133)and the CEUS-guided group(n=151).PCNB was performed using a core needle(16-gauge or 18-gauge).Internal necrosis,diagnostic yield,and diagnostic accuracy were compared between the two groups.Results:The predominant final diagnosis of the cases in this study was thymoma(29.7%),lymphoma(20.5%),thymic carcinoma(13.3%),and germ cell tumour(13.3%),respectively.There was no significant difference in patient age,sex,number of percutaneous biopsies,or display rate of internal necrosis on conventional US between the two groups.The rate of internal necrosis of the lesions was significantly higher after contrast agent injection(72.2%vs.41.7%;P<0.001).The CEUS-guided group had a higher diagnostic yield than the US-guided group(100%vs.89.5%,P<0.001).There was no significant difference between the diagnostic accuracy of the CEUSguided and US-guided groups(97.3%vs.97.4%;P=1.000).None of the patients experienced adverse reactions or complications after US-guided or CEUS-guided PCNB.Conclusions:CEUS-guided PCNB can improve the diagnostic yield by optimizing the biopsy procedure.
基金Supported by grant 10-1854-Scha I from Deutsche Krebshilfe, grant Scha778/2-1 from DFG to S.S. and Graduiertenkolleg Nu-cleoprotein complexes to S.S. and W.H.G.
文摘AIM: To study the expression of HBV enhancer Ⅱ by transcription factor COUP-TF1. METHODS: In order to study the regulation of HBV variants in the vicinity of the NRRE we cloned luciferase constructs containing the HBV enhancer Ⅱ from variants and from HBV genotypes A and D and cotransfected them together with expression vectors for COUP-TF1 into HepG2 cells. RESULTS: Our fi ndings show that enhancer Ⅱ of HBV genotype A is also repressed by COUP-TF1. In contrast, two different enhancer Ⅱ constructs of HBV genotype D were activated by COUP-TF1. The activation was independent of the NRRE because a natural variant with a deletion of nt 1763-1770 was still activated by COUP- TF1. CONCLUSION: Regulation of transcription of the HBV genome seems to differ among HBV genomes derived from different genotypes. These differences in transcriptional control among HBV genotypes may be the molecular basis for differences in the clinical course among HBV genotypes.
基金supported by the National Natural Science Foundation of China(No.51603055)the Natural Science Foundation of Heilongjiang Province(No.QC2017055)+1 种基金the China Postdoctoral Science Foundation(Nos.2016M601424,2017T100236)the Postdoctoral Foundation of Heilongjiang Province(Nos.LBH-Z16059,LBH-TZ10)。
文摘In this work,a blue emitter with a 3 D rigid structure composed of multiple spirobifluorene(3-Spiro) has been synthesized and characterized.Through a detailed study of the electrochemical and photophysical properties of 3-Spiro,we have evidenced that 3-Spiro can be applied as an active component of organic light-emitting diodes(OLEDs).The device with 5% doping rate of 4 CzPNPh exhibits high external quantum efficiency(EQE) of 11%,which proves the potential of 3 D rigid structure emitters for OLEDs.
基金the National 863 Programof China(2006AA10Z224-1)the National NaturalScience Foundation of China(40431001)
文摘The objective of this study is to provide scientific guidance for optimizing agricultural field nitrogen management that is based on the evaluation of current nitrogen application practice in Jiangsu Province, China, in 2000. The agricultural nitrogen models, consist of the soil mineralization model, the organic manure nitrogen releasing model, and the nitrogenous fertilizer use efficiency model. These models combined with the geographic information system technique were used to describe the spatial variability of nitrogen released from soil and organic manure and to identify its contributing factors. The comparison of the nitrogen fertilizer amount required by croplands, which was simulated by the models with the actual nitrogen fertilizer applied rate, was used to evaluate the current nitrogen application. The results showed that nitrogen was excessively applied in 71.8% croplands, given that the actual crop yield was desired. The excessive nitrogen amounted to 760 kiloton, accounting for 41.5% of the total nitrogen applied. Given that the actual highest yield was desired, nitrogen was reduced in 64.3% croplands. The total shortage of nitrogen was about 800 kiloton. Low use efficiency of nitrogen fertilizer was found in Taihu Lake area, Nanjing-Zhenjiang hilly area, and Xuzhou area, whereas the east beach area of Jiangsu showed an obvious deficiency of nitrogen fertilizer inputs. A balance of nitrogen fertilizer in Jiangsu croplands between excessive and deficient application areas would greatly benefit economic and environmental advantages.
