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    题名 作者 年代 出处 被引量
1Modeling spatio-temporal distribution of soil moisture by deep learning-based cellular automata model显示文摘Soil moisture content (SMC) is a key hydrological parameter in agriculture,meteorology and climate change,and understanding of spatio-temporal distributions of SMC in farmlands is important to address the precise irrigation scheduling.However,the hybrid interaction of static and dynamic environmental parameters makes it particularly difficult to accurately and reliably model the distribution of SMC.At present,deep learning wins numerous contests in machine learning and hence deep belief network (DBN) ,a breakthrough in deep learning is trained to extract the transition functions for the simulation of the cell state changes.In this study,we used a novel macroscopic cellular automata (MCA) model by combining DBN to predict the SMC over an irrigated corn field (an area of 22 km^2) in the Zhangye oasis,Northwest China.Static and dynamic environmental variables were prepared with regard to the complex hydrological processes.The widely used neural network,multi-layer perceptron (MLP) ,was utilized for comparison to DBN.The hybrid models (MLP-MCA and DBN-MCA) were calibrated and validated on SMC data within four months,i.e.June to September 2012,which were automatically observed by a wireless sensor network (WSN) .Compared with MLP-MCA,the DBN-MCA model led to a decrease in root mean squared error (RMSE) by 18%.Thus,the differences of prediction errors increased due to the propagating errors of variables,difficulties of knowing soil properties and recording irrigation amount in practice.The sequential Gaussian simulation (s Gs) was performed to assess the uncertainty of soil moisture estimations.Calculated with a threshold of SMC for each grid cell,the local uncertainty of simulated results in the post processing suggested that the probability of SMC less than 25% will be difference in different areas at different time periods.The current results showed that the DBN-MCA model performs better than the MLP-MCA model,and the DBN-MCA model provides a powerful tool for predicting SMC in highly non-linear forms.Moreover,because modeling soil moisture by using environmental variables is gaining increasing popularity,DBN techniques could contribute a lot to enhancing the calibration of MCA-based SMC estimations and hence provide an alternative approach for SMC monitoring in irrigation systems on the basis of canals.SONG Xiaodong ZHANG Ganlin LIU Feng LI Decheng ZHAO Yuguo YANG Jinling 2016Journal of Arid Land2016,8,5:20
2Adaptive Finite Element Modeling of Marine Controlled-Source Electromagnetic Fields in Two-Dimensional General Anisotropic Media显示文摘In this paper, we extend the scope of numerical simulations of marine controlled-source electromagnetic (CSEM) fields in a particular case of anisotropy (dipping anisotropy) to the general case of anisotropy by using an adaptive finite element approach. In comparison to a dipping anisotropy case, the first order spatial derivatives of the strike-parallel components arise in the partial differential equations for generally anisotropic media, which cause a non-symmetric linear system of equations for finite element modeling. The adaptive finite element method is employed to obtain numerical solutions on a sequence of refined unstructured triangular meshes, which allows for arbitrary model geometries including bathymetry and dipping layers. Numerical results of a 2D anisotropic model show both anisotropy strike and dipping angles have great influence on the marine CSEM responses.LI Yuguo LUO Ming PEI Jianxin 2013Journal of Ocean University of China2013,12,1:12
3Chinese kangs and building energy consumption显示文摘Chinese kangs are an integrated system for cooking, sleeping and heating in rural Northern China with more than 2000 years history. In 2004 there were 67 million Chinese kangs used by 44 million rural families or 174 million people. Chinese kangs store surplus heat from stove during cooking and re-leases it later for both home heating and localized bed heating. Such a widely used heating system has been rarely studied. Understanding kangs is important for developing new effective home heating systems for better energy efficiency and improving indoor air quality in Northern China. In this paper, we review and present some preliminary results from our field measurement and mathematical mod-eling, and discuss the development of Chinese kangs as related to future energy consumption in rural homes, and building energy consumption in China in general. We suggest that transition and new technologies for rural home heating in Northern China, i.e. the future of Chinese kangs, should be considered as the top priority in managing future building energy consumption in China.LI YuGuo ZHUANG Zhi LIU JiaPing 2009Chinese Science Bulletin2009,54,6:11
4Association of cystatin C level and cardiovascular prognosis for patients with preexisting coronary heart disease:a meta-analysis显示文摘The association of circulating levels of cystatin C(CysC)and risk of recurrent cardiovascular events in patients with preexisting coronary heart disease are uncertain.To qualitatively and quantitatively address this issue,we performed a random meta-analysis of results from prospective studies on the topic.We searched electronic and printed sources(up to 16 October 2011)using keywords and retrieved articles for seven prospective studies according to the selection criteria.Data were abstracted and meta-analysis was performed using the random-effects model(RevMan 5.0.23 software).The cohorts involved 4,576 patients with preexisting coronary heart disease(CHD)and normal or mild chronic kidney disease,and follow-up ranged from 5.6 to 40.6 months.Highest versus lowest baseline CysC level was significantly associated with increased risk of cardiovascular events(OR 2.30,95%CI 1.80–2.94),all-cause mortality(OR 5.69,95%CI 3.70–8.74),but not with recurrent MI(OR 1.75,95%CI 0.77–4.00).In heterogeneity testing for studies reporting cardiovascular events and all-cause mortality,no significant heterogeneity was found,and exclusion of any single study did not alter the overall finding.For risk of recurrent MI,significant heterogeneity was found among the five trials(v2=13.16,P=0.01,I2=70%)and exclusion of the Taglieri et al.[12]study from the analysis resulted in a rise in relative risk(OR 2.36,95%CI 1.09–5.15).In conclusion,for patients with established CHD,high baseline level of CysC is associated with increased risk of cardiovascular events and all-cause death during long-term follow-up.Ruijian Li Panpan Hao Yuguo Chen Yun Zhang 2014Chinese Science Bulletin2014,59,5:8
5Experimental Study on Preparation of Natural Gas Hydrate by Crystallization显示文摘In this paper, the saturated solution crystallization method is proposed to promote the formation of hydrate by means of the known similarities between the hydrate formation process and the crystallization process. In this method,adding the second phase crystals was used to replace the spontaneous formation of hydrate crystal nuclei to form hydrate.The effects of saturated Na_2SO_4, MgSO_4, NH_4HCO_3 and CuSO_4 solutions on the formation rates of natural gas hydrate and gas storage capacity were investigated. The results showed that the saturated solution had an influence on the hydrate formation process. Under the given experimental conditions, the saturated Na_2SO_4 solution showed a highest increase in the hydrate formation rate, and the average hydrate formation rate in its presence was 11.8 times higher than that obtained in the deionized water. Moreover, the largest formation rate of gas hydrates observed in the saturated Na_2SO_4 solution was 386 times bigger than that in the deionized water, and the gas storage capacity increased by 10 times. In addition, the average hydrate formation rate in the saturated Mg SO_4 solution was faster than that in water by 20 times. The largest formation rate of gas hydrates in the saturated MgSO_4 solution was 165 times faster than that obtained in the deionized water, and the gas storage capacity increased by 6.2 times. The saturated NH_4HCO_3 and saturated CuSO_4 solutions also influenced the formation process of hydrate. Therefore, the crystallization method of saturated solution can be used to achieve a highefficiency preparation of natural gas hydrates, which provides theoretical guidance for the storage of natural gas in the form of hydrate.Ma Shihui Pan Zhen Li Ping Wu Yuguo Li Bingfan Kang Jinke Zhang Zhien 2017China Petroleum Processing & Petrochemical Technology2017,19,1:7
6SnO_2 hollow spheres:Polymer bead-templated hydrothermal synthesis and their electrochemical properties for lithium storage显示文摘SnO2 hollow spheres have been synthesized via a facile hydrothermal method using sulfonated polystyrene beads as a template followed by a calcination process in air.X-ray diffraction,scanning electron microscopy,and transmission electron microscopy show that the as-obtained SnO2 hollow spheres have a wall thickness of about 50 nm,and consist of nanosized SnO2 particles with a mean diameter of about 15 nm.Electrochemical measurements indicate that the SnO2 hollow spheres exhibit improved electrochemical performance in terms of specific capacity and rate capability in comparison with commercial SnO2 when used as anode materials for lithium-ion batteries.The enhanced performance may be attributed to the spherical and hollow structure,as well as the building blocks of SnO2 nanoparticles.YIN YaXia XIN Sen WAN LiJun LI CongJu GUO YuGuo 2012Science China Chemistry2012,55,7:6
7The transient fracture behavior for a functionally graded layered structure subjected to an in-plane impact load显示文摘The transient fracture behavior of a functionally graded layered structure subjected to an in-plane impact load is investigated. The studied structure is composed of two homogeneous layers and a functionally graded interlayer with a crack perpendicular to the boundaries. The impact load is applied on the face of the crack. Fourier transform and Laplace transform methods are used to formulate the present problem in terms of a singular integral equation in Laplace transform domain. Considering variations of parameters such as the nonhomogeneity constant, the thickness ratio and the crack length, the dynamic stress intensity factors (DSIFs) in time domain are studied and some meaningful conclusions are obtained.Licheng Guo Linzhi Wu Yuguo Sun Li Ma 2005Acta Mechanica Sinica2005,21,3:5
8Regional Soil Mapping Using Multi-Grade Representative Sampling and a Fuzzy Membership-Based Mapping Approach显示文摘High-resolution and detailed regional soil spatial distribution information is increasingly needed for ecological modeling and land resource management. For areas with no point data, regional soil mapping includes two steps: soil sampling and soil mapping. Because sampling over a large area is costly, efficient sampling strategies are required. A multi-grade representative sampling strategy, which designs a small number of representative samples with different representative grades to depict soil spatial variations at different scales,could be a potentially efficient sampling strategy for regional soil mapping. Additionally, a suitable soil mapping approach is needed to map regional soil variations based on a small number of samples. In this study, the multi-grade representative sampling strategy was applied and a fuzzy membership-weighted soil mapping approach was developed to map soil sand percentage and soil organic carbon(SOC) at 0–20 and 20–40 cm depths in a study area of 5 900 km2 in Anhui Province of China. First, geographical sub-areas were delineated using a parent lithology data layer. Next, fuzzy c-means clustering was applied to two climate and four terrain variables in each stratum. The clustering results(environmental cluster chains) were used to locate representative samples. Evaluations based on an independent validation sample set showed that the addition of samples with lower representativeness generally led to a decrease of root mean square error(RMSE). The declining rates of RMSE with the addition of samples slowed down for 20–40 cm depth, but fluctuated for 0–20 cm depth. The predicted SOC maps based on the representative samples exhibited higher accuracy, especially for soil depth 20–40 cm, as compared to those based on legacy soil data. Multi-grade representative sampling could be an effective sampling strategy at a regional scale. This sampling strategy, combined with the fuzzy membership-based mapping approach, could be an optional effective framework for regional soil property mapping. A more detailed and accurate soil parent material map and the addition of environmental variables representing human activities would improve mapping accuracy.YANG Lin A-Xing ZHU ZHAO Yuguo LI Decheng ZHANG Ganlin ZHANG Shujie Lawrence E. BAND 2017Pedosphere2017,27,2:5
9The Remote Sensing of Sargassum on Daya BayLi Tiefang (Center for Remote Sensing, Zhongshan University) Liu Huai, Fang Hongda (South China Sea Marine Environmental Monitoring Center, SOA) Dong Yuguo (Guangzhou Institute of New Techniques in Geology, Academic Sinica) 1990遥感信息1990,12,A02:5
10Novel fibrin-fibronectin matrix accelerates mice skin wound healing显示文摘Plasma fibrinogen(F1)and fibronectin(pFN)polymerize to form a fibrin clot that is both a hemostatic and provisional matrix for wound healing.About 90%of plasma F1 has a homodimeric pair ofγchains(γγF1),and 10%has a heterodimeric pair ofγand more acidicγ′chains(γγ′F1).We have synthesized a novel fibrin matrix exclusively from a 1:1(molar ratio)complex ofγγ′F1 and pFN in the presence of highly active thrombin and recombinant Factor XIII(rFXIIIa).In this matrix,the fibrin nanofibers were decorated with pFN nanoclusters(termedγγ′F1:pFN fibrin).In contrast,fibrin made from 1:1 mixture ofγγF1 and pFN formed a sporadic distribution of“pFN droplets”(termedγγF1+pFN fibrin).Theγγ′F1:pFN fibrin enhanced the adhesion of primary human umbilical vein endothelium cells(HUVECs)relative to theγγF1+FN fibrin.Three dimensional(3D)culturing showed that theγγ′F1:pFN complex fibrin matrix enhanced the proliferation of both HUVECs and primary human fibroblasts.HUVECs in the 3Dγγ′F1:pFN fibrin exhibited a starkly enhanced vascular morphogenesis while an apoptotic growth profile was observed in theγγF1+pFN fibrin.Relative toγγF1+pFN fibrin,mouse dermal wounds that were sealed byγγ′F1:pFN fibrin exhibited accelerated and enhanced healing.This study suggests that a 3D pFN presentation on a fibrin matrix promotes wound healing.Carlos Poblete Jara Ou Wang Thais Paulino do Prado Ayman Ismail Frank Marco Fabian Han Li Licio A.Velloso Mark A.Carlson William Burgess Yuguo Lei William H.Velander Eliana P.Araújo 2020Bioactive Materials2020,5,4:5
11MATRIEX imaging:multiarea two-photon real-time in vivo explorer显示文摘Two-photon laser scanning microscopy has been extensively applied to study in vivo neuronal activity at cellular and subcellular resolutions in mammalian brains.However,the extent of such studies is typically confined to a single functional region of the brain.Here,we demonstrate a novel technique,termed the multiarea two-photon real-time in vivo explorer(MATRIEX),that allows the user to target multiple functional brain regions distributed within a zone of up to 12mm in diameter,each with a field of view(FOV)of ~200μm in diameter,thus performing two-photon Ca2+imaging with single-cell resolution in all of the regions simultaneously.For example,we demonstrate real-time functional imaging of single-neuron activities in the primary visual cortex,primary motor cortex and hippocampal CA1 region of mice in both anesthetized and awake states.A unique advantage of the MATRIEX technique is the configuration of multiple microscopic FOVs that are distributed in three-dimensional space over macroscopic distances(>1 mm)both laterally and axially but that are imaged by a single conventional laser scanning device.In particular,the MATRIEX technique can be effectively implemented as an add-on optical module for an existing conventional single-beam-scanning two-photon microscope without requiring any modification to the microscope itself.Thus,the MATRIEX technique can be readily applied to substantially facilitate the exploration of multiarea neuronal activity in vivo for studies of brain-wide neural circuit function with single-cell resolution.Mengke Yang Zhenqiao Zhou Jianxiong Zhang Shanshan Jia Tong Li Jiangheng Guan Xiang Liao Bing Leng Jing Lyu Kuan Zhang Min Li Yan Gong Zhiming Zhu Junan Yan Yi Zhou Jian K Liu Zsuzsanna Varga Arthur Konnerth Yuguo Tang Jinsong Gao Xiaowei Chen Hongbo Jia 2019Light(Science & Applications)2019,8,1:4
12Vertical distribution and storage of soil organic and inorganic carbon in a typical inland river basin,Northwest China显示文摘Knowledge of soil carbon(C) distribution and its relationship with the environment can improve our understanding of its biogeochemical cycling and help to establish sound regional models of C cycling. However, such knowledge is limited in environments with complex landscape configurations. In this study, we investigated the vertical distribution and storage of soil organic carbon(SOC) and soil inorganic carbon(SIC) in the 10 representative landscapes(alpine meadow, subalpine shrub and meadow, mountain grassland, mountain forest, typical steppe, desert steppe, Hexi Corridor oases cropland, Ruoshui River delta desert, Alxa Gobi desert, and sandy desert) with contrasting bioclimatic regimes in the Heihe River Basin, Northwest China. We also measured the 87 Sr/86 Sr ratio in soil carbonate to understand the sources of SIC because the ratio can be used as a proxy in calculating the contribution of pedogenic inorganic carbon(PIC) to total SIC. Our results showed that SOC contents generally decreased with increasing soil depth in all landscapes, while SIC contents exhibited more complicated variations along soil profiles in relation to pedogenic processes and parent materials at the various landscapes. There were significant differences of C stocks in the top meter among different landscapes, with SOC storage ranging from 0.82 kg C/m^2 in sandy desert to 50.48 kg C/m^2 in mountain forest and SIC storage ranging from 0.19 kg C/m^2 in alpine meadow to 21.91 kg C/m^2 in desert steppe. SIC contributed more than 75% of total C pool when SOC storage was lower than 10 kg C/m^2, and the proportion of PIC to SIC was greater than 70% as calculated from Sr isotopic ratio, suggesting the critical role of PIC in the C budget of this region. The considerable variations of SOC and SIC in different landscapes were attributed to different pedogenic environments resulted from contrasting climatic regimes, parent materials and vegetation types. This study provides an evidence for a general trade-off pattern between SOC and SIC, showing the compensatory effects of environmental conditions(especially climate) on SOC and SIC formation in these landscapes. This is largely attributed to the fact that the overall decrease in temperature and increase in precipitation from arid deserts to alpine mountains simultaneously facilitate the accumulation of SOC and depletion of SIC.YANG Fan HUANG Laiming YANG Renmin YANG Fei LI Decheng ZHAO Yuguo YANG Jinling LIU Feng ZHANG Ganlin 2018Journal of Arid Land2018,10,2:4
13Effect of optimal combination of Huangqi(Radix Astragali Mongolici) and Ezhu(Rhizoma Curcumae Phaeocaulis) on proliferation and apoptosis of A549 lung cancer cells显示文摘OBJECTIVE: To investigate the effect of optimal combination(E) of Huangqi(Radix Astragali Mongolici) and Ezhu(Rhizoma Curcumae Phaeocaulis) on proliferation and apoptosis of A549 lung cancer cells and the possible mechanism underpinning the action.METHODS: A uniform design method was used to optimize the E of Huangqi(Radix Astragali Mongolici) and Ezhu(Rhizoma Curcumae Phaeocaulis) in A549 lung cancer cells. MTS assay was applied to analyze the effect of the component formula ofHuangqi(Radix Astragali Mongolici) and Ezhu(Rhizoma Curcumae Phaeocaulis) on A549 cells viability in various uniform design groups. A549 cells with exponential growth in routine culture were exposed to Co Cl_2(200 μmol/L) to mimic hypoxic conditions. Group 0 was treated with RPMI-1640, the group Co Cl_2 was treated with Co Cl_2(200 μmol/L),the group DDP + Co Cl_2 was treated with 4 mg/L Cisplatin injection(DDP) + Co Cl_2(200 μmol/L), and the drug group was treated with various dose of E(0.5 E, 1 E, 2 E) + Co Cl_2(200 μmol/L). All groups were cultured for 24 h. Cell apoptosis was measured by Annexin V-FITC/propidium iodide double staining and flow cytometry. Western blot assay and quantitative real-time polymerase chain reaction(q RT-PCR) were employed to detect the protein and m RNA expression of B-celllymphoma-2(Bcl-2),Bcl-2-associated X protein(Bax) and cysteinyl aspartate specific proteinase-3(caspase-3).RESULTS: The E obtained by the uniform design was comprise of 200 mg/L Astragalus polysaccharide(X1) and 32 mg/L Curcumin(X3). Group DDP+Co Cl_2, group 1 E + Co Cl_2 and group 2 E + Co Cl_2 promoted the apoptosis of A549 cells(P < 0.05). Group1 E + Co Cl_2 and group 2 E + Co Cl_2 had no statistically significant differences compared with the group DDP + Co Cl_2(P > 0.05). Compared with group 0, various doses of E + Co Cl_2 could up-regulate the expression of Bax and caspase-3 and down-regulate the expression of Bcl-2 at protein and m RNA levels(P < 0.05).CONCLUSION: Astragalus polysaccharide and Curcumin was the optimal combination of Huangqi(Radix Astragali Mongolici) and Ezhu(Rhizoma Cur-cumae Phaeocaulis). E promoted the apoptosis of A549 cells. Combination of Astragalus polysaccharide and Curcumin increased the expression of Bax and caspase-3, and decreased the expression of Bcl-2 to initiate apoptosis in A549 cells under chemical-induced hypoxia.Xu Chengyong Wang Yuguo Feng Jian Qin Li Xu Ran Dou Yongqi 2018Journal of Traditional Chinese Medicine2018,38,3:4
14Acute toxicity evaluation for quinolone antibiotics and their chlorination disinfection processes显示文摘Acute toxicity of 21 quinolone antibiotics was monitored using photobacterium Vibrio fischeri assay.The minimum IC20(inhibitory concentration for 20%luminescence elimination)was obtained at the least 18.86μmol/L for the tested quinolones.A quantitative structure–activity relationship model was established to investigate the possible mechanism for the acute toxicity.The critical physicochemical descriptors,describingσandπatom electronegativity,implied that the electron transfer might occur between the quinolones and photobacterium V.fischeri.Although the quinolones exhibited limited acute toxicity to photobacterium,toxicity elevation was detected after their chlorination.Hence,chlorination disinfection treatment of quinolone-containing water should be of concerns.Min Li Dongbin Wei Yuguo Du 2014Journal of Environmental Sciences2014,26,9:4
15Mapping Soil Texture Based on Field Soil Moisture Observations at a High Temporal Resolution in an Oasis Agricultural Area显示文摘Due to the almost homogeneous topography in low relief areas, it is usually difficult to make accurate predictions of soil properties using topographic covariates. In this study, we examined how time series of field soil moisture observations can be used to estimate soil texture in an oasis agricultural area with low relief in the semi-arid region of northwest China. Time series of field-observed soil moisture variations were recorded for 132 h beginning at the end of an irrigation event during which the surface soil was saturated.Spatial correlation between two time-adjacent soil moisture conditions was used to select the factors for fuzzy c-means clustering. In each of the ten generated clusters, soil texture of the soil sample with the maximum fuzzy membership value was taken as the cluster centroid. Finally, a linearly weighted average was used to predict soil texture from the centroids. The results showed that soil moisture increased with the increase of clay and silt contents, but decreased with the increase of sand content. The spatial patterns of soil moisture changed during the entire soil drying phase. We assumed that these changes were mainly caused by spatial heterogeneity of soil texture. A total of 64 independent samples were used to evaluate the prediction accuracy. The root mean square error(RMSE)values of clay, silt and sand were 1.63, 2.81 and 3.71, respectively. The mean relative error(RE) values were 9.57% for clay, 3.77% for silt and 12.83% for sand. It could be concluded that the method used in this study was effective for soil texture mapping in the low-relief oasis agricultural area and could be applicable in other similar irrigation agricultural areas.YANG Renmin LIU Feng ZHANG Ganlin ZHAO Yuguo LI Decheng YANG Jinling YANG Fei YANG Fan 2016Pedosphere2016,26,5:3
16Effects of Uncertainties in the Position and Orientation of Both the Transmitter and Receivers on Marine Controlled-Source Electromagnetic Data显示文摘Simulation and interpretation of marine controlled-source electromagnetic(CSEM) data often approximate the transmitter source as an ideal horizontal electric dipole(HED) and assume that the receivers are located on a flat seabed.Actually,however,the transmitter dipole source will be rotated,tilted and deviated from the survey profile due to ocean currents.And free-fall receivers may be also rotated to some arbitrary horizontal orientation and located on sloping seafloor.In this paper,we investigate the effects of uncertainties in the transmitter tilt,transmitter rotation and transmitter deviation from the survey profile as well as in the receiver's location and orientation on marine CSEM data.The model study shows that the uncertainties of all position and orientation parameters of both the transmitter and receivers can propagate into observed data uncertainties,but to a different extent.In interpreting marine data,field data uncertainties caused by the position and orientation uncertainties of both the transmitter and receivers need to be taken into account.XU Zhenhuan LIU Ying LI Yuguo 2016Journal of Ocean University of China2016,15,1:3
17Formation pathways of brominated products from benzophenone-4 chlorination in the presence of bromide ions显示文摘The brominated products,formed in chlorination treatment of benzophenone-4 in the presence of bromide ions,were identified,and the formation pathways were proposed.Under disinfection conditions,benzophenone-4 would undertake electrophilic substitution generating mono-or di-halogenated products,which would be oxidized to esters and further hydrolyzed to phenol derivatives.The generated catechol intermediate would be transformed into furan-like heterocyclic product.The product species were p H-dependent,while benzophenone-4 elimination was chlorine dose-dependent.When the chlorination treatment was performed on ambient water spiked with benzophenone-4 and bromide ions,most of brominated byproducts could be detected,and the acute toxicity significantly increased as well.Ming Xiao Dongbin Wei Liping Li Qi Liu Huimin Zhao Yuguo Du 2014Journal of Environmental Sciences2014,26,12:3
18An efficient route towards R-2-phenoxypropionic acid synthesis for biotransformative production of R-2-(4-hydroxyphenoxy)propionic acid显示文摘R2(4hydroxyphenoxy)propionic acid(RHPPA)is a key intermediate for the synthesis of classic herbicides with high selectivity against grassy weed.The main route for RHPPA biosynthesis is to hydroxylate the substrate R2phenoxypropionic acid(RPPA)at C4 position with microbes.In order to provide sufficient RPPA for the industrial production of RHPPA,an effective RPPA synthesis method was established and optimized in this work.The synthesis process mainly consisted of two steps:(1)synthesis of S2chloropropionic acid from Lalanine via diazotization and chlorination reactions;and(2)synthesis of RPPA from S2chloropropionic acid and phenol via etherification reaction.The optimal reaction conditions were as follows:HCl:NaNO_(2):KI:LAla=2.0:1.2:0.7:1.0(in molar),125℃reflux for 1.5 h,with KI as catalyst,and KI:S2chloropropionic acid:phenol=0.075:1.2:1.0(in molar).Under these conditions,an improved molar conversion rate(74.9%,calculated in phenol)was achieved.After extraction using anionic exchange resin Amberlite IRA400(CI),RPPA product with a purity of 95.08%was obtained.The purified RPPA was identified and evaluated in the application of the biotransformative production of RHPPA.The results indicated that the synthesized RPPA supported the RHPPA biosynthesis with a comparable yield as that of the standard RPPA.The RPPA synthesis method provided herein exhibited the advantages of low price and easy availability of raw materials,less toxicity of reagents,simple manipulations,and low equipment/instrument requirements.Haiyan Zhou Yizuo Li Rui Jiang Xianlin Wang Yuanshan Wang Yaping Xue Yuguo Zheng 2021Chinese Journal of Chemical Engineering2021,34,4:2
19Experimental study of freak waves due to three-dimensional island terrain in random wave显示文摘An experimental study is carried out for waves passing an isolated reef terrain in a wave tank. A three-dimensional model of a representative and isolated reef terrain in the West Pacific is built. Random wave trains with various periods and wave heights are generated by a wave maker using the improved JONSWAP spectrum. It is observed that there are different kinds of generation processes and waveforms of freak waves. The freak wave factor Hm/Hs (where Hm is the maximum wave height of wave series, and Hs is significant wave height) is analyzed in detail, in terms of the skewness, kurtosis and water depth, as well as the relationship between freak wave height H& and skewness. The freak wave factor Hm/Hs is found to be in positive correlation with the kurtosis, while larger H[x tends to be related with bigger skewness. The rapid variation of water depth, such as slope and seamount, contributes to the occurrence probability of freak waves.Li Zou Aimin Wang Zhen Wang Yuguo Pei Xiaolong Liu 2019Acta Oceanologica Sinica2019,38,6:2
20Influence of Social Capital on Rural Tourism Development显示文摘In order to explore the relationship between social capital and rural tourism development effect and improve the development of rural tourism,this study takes Liutai Village in Shandong Province,9 villages of Mangxin Township and Yuanyi Village in Xinjiang as examples and conducts empirical research.The result of exploratory factor analysis shows that social capital is divided into bonding type and bridging type,which have different characteristics and functions.The result of multiple regression analysis shows that social capital of both the two types has a significant positive impact on the development of rural tourism.In the current process of rural tourism development,the positive influence of bonding social capital is greater than that of bridging social capital.Based on the results of the empirical analysis,this paper puts forward the countermeasures and suggestions for the development of rural tourism.Xiu LI Yuguo WANG 2020Asian Agricultural Research2020,12,11:2
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