A metallurgical model for austenite coarsening in the coarse-grained heat-affected zone(CGHAZ)containing titanium nitride(TiN)precipitation was studied.Unlike traditional methods estimating pinning capability based on...A metallurgical model for austenite coarsening in the coarse-grained heat-affected zone(CGHAZ)containing titanium nitride(TiN)precipitation was studied.Unlike traditional methods estimating pinning capability based on the precipitation size after welding,a proposed dissolution and coarsening model was applied to study the changes in TiN precipitation size and the associated pinning forces.The transmission electron microscope was used to analyze the size distribution of TiN particles before and after the welding thermal cycle.The size distribution showed a log-normal distribution before the thermal cycle.The prediction of post-thermal cycle size distributions with the proposed model was in agreement with the experimental results.Considering the short holding time at high temperature during welding,the thermodynamic stability conditions required for limiting grain size model cannot be achieved.A simple kinetic model for the prediction of austenite grain size in CGHAZ was established.Finally,the predicted austenite grain sizes agree better with experimental results than the conventional approach.展开更多
H pylori is etiologically associated with gastritis, gas-tric and duodenal ulcers, gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. Eradicating H pylori may convert rapidly the outcome of ...H pylori is etiologically associated with gastritis, gas-tric and duodenal ulcers, gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. Eradicating H pylori may convert rapidly the outcome of related diseases with the use of more accurate diagnostic molecular tests. Indeed some of the tests cannot give the evidence of current infection; H pylori can be detected by noninvasive and invasive methods, the latter requiring an endoscopy. Eradication failure is a big problem in H pylori infection. Recently, clarithromycin resistance in H pylori strains is increasing and eradicati-on therapy of this bacterium is becoming more difficult. Molecular methods have frequently been applied besides phenotypic methods for susceptibility testing to detect clarithromycin resistance due to mutations in the 2143 and 2144 positions of 23S rRNA gene. Fluorescence in situ hybridization (FISH) method on paraffin embedded tissue is a rapid, accurate and cost-effective method for the detection of H pylori infection and to determine clarithromycin resistance within three hours according to the gold standards as a non-culture method. This method can also be applied to fresh biopsy samples and the isolated colonies from a culture of H pylori, detecting both the culturable bacillary forms and the coccoid forms of H pylori, besides the paraffin embedded tissue secti-ons. This technique is helpful for determining the bac-terial density and the results of treatment where clarith-romycin has been widely used in populations to increase the efficacy of the treatment and to clarify the treatment failure in vitro.展开更多
The distribution of rDNA was visualized in interphase nuclei of tumor promoter treated human lymphocytes in comparison with the mltogen Phytoheamagglutinin (PHA) effects by using an in situ hybridization fluorescent m...The distribution of rDNA was visualized in interphase nuclei of tumor promoter treated human lymphocytes in comparison with the mltogen Phytoheamagglutinin (PHA) effects by using an in situ hybridization fluorescent method. The procedure involves biotinylated rDNA as the probe and FITC-avidin as detection system. Silver (Ag) staining was used to visualize nucleoli. In the interphase nuclei of most of the nonstimulated control lymphocytes, only one small Ag-stained nucleolus could be seen. The in situ hybridization, however, revealed one to several agglomerations of rDNA fluorescent spots. With tumor promoting herb extract WCE (40 μg/ml) or TPA (60 ng/ ml) treatment, the Interphase nucleoli increased slightly in number with the morphology alteration into larger, reticular or compact granular types. Ag-stained particles also increased in number. The number of the in situ hybridization rDNA fluorescent spots and dots increased markedly and largereticulate formations of numerous rDNA spots were seen. This phenomenum resembles to the changes in PHA stimulated lymphocytes. Statistic analysized data showed signifcant difference between control and drug- treated cells. These results indicate that transcriptionally activated rDNA and amplification of total rDNA was induced by the used tumor promoters.展开更多
Agrobacterium-mediated gene transformation in Brassica crops is a time-con-suming and labor-cost method （tissue culture and plant regeneration） in a genotype-depen-dent way. Here we described a new method 7n...Agrobacterium-mediated gene transformation in Brassica crops is a time-con-suming and labor-cost method （tissue culture and plant regeneration） in a genotype-depen-dent way. Here we described a new method 7n situ pistil delivery （ISPDy method with no tissue culture and adaptive to three Brassica species. Briefly this method can be stated as placement of a liquid drop containing binary vector DNA onto the cut surface of emasculated and artificial pollinated Brassica stigma. Transformation rate （Basta-resistant seedlings per 100 pistils） of different species ranged from 0.4% to 16.3%. Factors affecting transforma-tion success included tinning and buffer type. PCR and Southern blot confirmed transgenic events. Reciprocal cross showed reporter gene steadily inherited in nuclear transformed pattern. GUS histochemical assay of transgenic immature seeds showed stained embroys and endosperm in the same seed, indicating DNA delivered through style and integrated into Brassica seed/genome after double fertilization.展开更多
Covalent organic frameworks(COFs)are a novel type of crystalline porous organic polymer materials recently developed.It has several advantages in chromatographic separation field,such as high thermal stability,porosit...Covalent organic frameworks(COFs)are a novel type of crystalline porous organic polymer materials recently developed.It has several advantages in chromatographic separation field,such as high thermal stability,porosity,structural regularity,and large specific surface area.Here,a novel spherical COF 1,3,5-tris(4-aminophenyl)benzene(TAPB)and 2,5-bis(2-propyn-1-yloxy)-1,4-benzenedicarboxaldehyde(BPTA)was developed as an electrochromatographic stationary phase for capillary electrochromatography separation.The COF TAPB-BPTA modified capillary column was fabricated via a facile in situ growth method at room temperature.The characterization results of scanning electron microscopy(SEM),Fourier transform infrared(FT-IR)spectroscopy,and X-ray diffraction(XRD)confirmed that COF TAPB-BPTA were successfully modified onto the capillary inner surface.The electrochromatography separation performance of the COF TAPB-BPTA modified capillary was investigated.The prepared column demonstrated outstanding separation performance toward alkylbenzenes,phenols,and chlorobenzenes compounds.Furthermore,the baseline separations of non-steroidal anti-inflammatory drugs(NSAIDs)and parabens with good efficiency and high resolution were achieved.Also,the prepared column possessed satisfactory precision of the intra-day runs(n=5),inter-day runs(n=3),and parallel columns(n=3),and the relative standard deviations(RSDs)of the retention times of tested alkylbenzenes were all less than 2.58%.Thus,this new COF-based stationary phase shows tremendous application potential in chromatographic separation field.展开更多
Li4Ti5O12 powders were prepared by so-gel method using tetrabutyl titanate,lithium acetate and absolute alcohol as starting materials.Li4Ti5O12-polyaniline(Li4Ti5O12-PAn)composite was prepared by in situ polymerizatio...Li4Ti5O12 powders were prepared by so-gel method using tetrabutyl titanate,lithium acetate and absolute alcohol as starting materials.Li4Ti5O12-polyaniline(Li4Ti5O12-PAn)composite was prepared by in situ polymerization method using aniline, ammonium persulfate and hydrochloricarried as starting materials.Li4Ti5O12-PAn composite was characterized by X-ray diffractometry(XRD),infrared spectrum(IR)combined with electrochemical tests.The results show that the electrical conductivity is enhanced obviously due to the introduction of PAn to Li4Ti5O12.Li4Ti5O12-PAn composite exhibits better high-rate capability and cyclability than Li4Ti5O12.The composite can deliver a specific capacity of 191.3 and 148.9 mA·h/g,only 0.13%and 0.61%of the capacity is lose after being discharged 80 times at 0.1C and 2.0C,respectively.展开更多
In situ-grown Mg-Al layered double hydroxide(LDH)films were obtained on an anodized AZ31 substrate,with the immersion of sample in different concentrations of Al^(3+)solution.The structure,composition and morphology o...In situ-grown Mg-Al layered double hydroxide(LDH)films were obtained on an anodized AZ31 substrate,with the immersion of sample in different concentrations of Al^(3+)solution.The structure,composition and morphology of LDH films were investigated by X-ray diffraction(XRD),Fourier transform infrared(FTIR)and scanning electronic microscopy(SEM),and the corrosion behavior of LDH films was further studied by electrochemical impedance spectroscopy(EIS).The influence of Al^(3+)concentration on the growth behavior of LDH was also discussed.The results indicated that the nest-like structure of MgAl-LDH film was composed of interconnected MgAl-LDH nanosheets.Besides,the LDH obtained in0.032 mol·L^(-1)Al^(3+)solution,possessing dense laminated structure,could effectively seal the porous surface of anodic oxide film.EIS results revealed that the samples coated with LDH films showed a higher electrochemical impedance,and thus,the corrosion resistance of samples coated with LDH films was signally improved compared with the anodized alloy.展开更多
Molybdenum disulfide(MoS_(2)),a typical two-dimensional transition metallic layered material,attracts tremendous attentions in the electrochemical energy storage due to its excellent physicochemical properties.However...Molybdenum disulfide(MoS_(2)),a typical two-dimensional transition metallic layered material,attracts tremendous attentions in the electrochemical energy storage due to its excellent physicochemical properties.However,with the deepening of the research and exploration of the lithium storage mechanism of these advanced MoS_(2)-based anode materials,the complex reaction process influenced by internal and external factors hinders the exhaustive understanding of the lithium storage process.To design stable anode material with high performance,it is urgent to review the mechanisms of reported anode materials and summarize the related factors that influence the reaction processes.This review aims to dissect all possible side reactions during charging and discharging process,uncover internal and external factors inducing various anode reactions and finally put forward strategies of controlling high cycling capacity and super-stable lithium storage capability of MoS_(2).This review will be helpful to the design of MoS_(2)-based lithium-ion batteries(LIBs) with excellent cycle performance to enlarge the application fields of these advanced electrochemical energy storage devices.展开更多
Numerous deep underground projects have been designed and constructed in China, which are beyond the current specifications in terms of scale and construction difficulty. The severe failure problems induced by high in...Numerous deep underground projects have been designed and constructed in China, which are beyond the current specifications in terms of scale and construction difficulty. The severe failure problems induced by high in situ stress, such as rockburst, spalling, damage of deep surrounding rocks, and timedependent damage, were observed during construction of these projects. To address these problems, the dynamic design method for deep hard rock tunnels is proposed based on the disintegration process of surrounding rocks using associated dynamic control theories and technologies. Seven steps are basically employed：（i） determination of design objective,（ii） characteristics of site, rock mass and project, and identification of constraint conditions,（iii） selection or development of global design strategy,（iv）determination of modeling method and software,（v） preliminary design,（vi） comprehensive integrated method and dynamic feedback analysis, and（vii） final design. This dynamic method was applied to the construction of the headrace tunnels at Jinping II hydropower station. The key technical issues encountered during the construction of deep hard rock tunnels, such as in situ stress distribution along the tunnels, mechanical properties and constitutive model of deep hard rocks, determination of mechanical parameters of surrounding rocks, stability evaluation of surrounding rocks, and optimization design of rock support and lining, have been adequately addressed. The proposed method and its application can provide guidance for deep underground projects characterized with similar geological conditions.展开更多
AgCl/Ti_(3)C_(2)@TiO_(2)ternary composites were prepared to form a heterojunction structure between AgCl and TiO_(2)and introduce Ti3C2 as a cocatalyst.The as-prepared AgCl/Ti_(3)C_(2)@TiO_(2)composites showed higher ...AgCl/Ti_(3)C_(2)@TiO_(2)ternary composites were prepared to form a heterojunction structure between AgCl and TiO_(2)and introduce Ti3C2 as a cocatalyst.The as-prepared AgCl/Ti_(3)C_(2)@TiO_(2)composites showed higher photocatalytic activity than pure AgCl and Ti_(3)C_(2)@TiO_(2)for photooxidation of a 1,4-dihydropyridine derivative(1,4-DHP)and tetracycline hydrochloride(TCH)under visible light irradiation(λ>400 nm).The photocatalytic activity of AgCl/Ti_(3)C_(2)@TiO_(2)composites depended on Ti_(3)C_(2)@TiO_(2)content,and the catalytic activity of the optimized samples were 6.9 times higher than that of pure AgCl for 1,4-DHP photodehydrogenation and 7.3 times higher than that of Ti_(3)C_(2)@TiO_(2)for TCH photooxidation.The increased photocatalytic activity was due to the formation of a heterojunction structure between AgCl and TiO_(2)and the introduction of Ti3C2 as a cocatalyst,which lowered the internal resistance,sped up the charge transfer,and increased the separation efficiency of photogenerated carries.Photogenerated holes and superoxide radical anions were the major active species in the photocatalytic process.展开更多
Conservation of genetic diversity of forest tree species represents the foundation for sustainable forest management and preservation of natural structure of forest stands in Croatia. Diversity of geographical regions...Conservation of genetic diversity of forest tree species represents the foundation for sustainable forest management and preservation of natural structure of forest stands in Croatia. Diversity of geographical regions in Croatia has generated various ecological conditions and thus diverse forest communities which are directly affected by habitat degradation, various anthropogenic effects like pollution of air and water, excessive use of certain more valuable species of forest trees and by the increasing impact of global climatic changes. The need for conservation of genetic diversity is related to the species pertaining to social broadleaves—the prevailing species in terms of economic utilization as Pedunculate Oak (Quercus robur), Sessile Oak (Quercus petraea) and Common Beech (Fagus sylvatica). Among the conifers Silver Fir (Abies alba) is the most endangered species, with more than 70% of its population being seriously damaged. Other native coniferous species must be preserved from a decrease in genetic diversity as well. Conservation of the noble broadleaves should encompass a larger number of species from various genera (Fraxinus, Alnus, Ulmus, Prunus, Juglans, Castanea, Sorbus, Acer, Malus, Pyrus, Tilia). These are partially endangered because of their exposure to different pests and diseases, as well as by permanent exploitation due to their technical value. Changes in hydrological conditions of rivers have led difficulties in regeneration of the riparian forests and decreased the genetic variability of European Black and White Poplar in their habitats (Populus nigra, P. alba). In Croatia’s Adriatic coastal areas, there is a need for conservation of genetic resources of Dalmatian Black Pine (P. nigra ssp. dalmatica) and Mediterranean Oaks (Quercus ilex, Quercus pubescens). Conservation of genetic diversity of various forest tree species is conducted within the programmes that include in situ and ex situ methods with ensuring quality forest reproductive materials. In Croatia, a total of 125 seed stands have been selected, covering a total area of 3885.53 ha. The ex situ method is implemented by establishment of a total of 50 plots (clonal seed orchards, provenances and progeny trials, clonal archives), covering 114.85 ha.展开更多
Efficient hydrogen production via photocatalysis with high utilization efficiency of Pt cocatalyst is of great importance for sustainable development. In this work, we report an in situ auto-reduction strategy to enca...Efficient hydrogen production via photocatalysis with high utilization efficiency of Pt cocatalyst is of great importance for sustainable development. In this work, we report an in situ auto-reduction strategy to encapsulate highly dispersed Pt clusters inside the cages of MIL-125-NH_(2). The amino groups in MIL-125-NH_(2) first react with formaldehyde to form reducing groups (i.e.,–NH-CH_(2)OH), which can in situ auto-reduce the confined Pt^(2+) ions to ultrasmall Pt clusters within the cavities. With optimized Pt content, photocatalytic H_(2) production over the obtained Pt(1.5)/MIL-125-NH-CH_(2)OH catalyst with 1.43 wt.% Pt loading achieved as high as 4,496.4 µmol·g^(-1)·h^(-1) under visible light (λ > 420 nm) due to the facilitated transfer and separation of the photo-induced charger carriers arising from the synergetic effects between highly dispersed Pt clusters and MIL-125-NH-CH_(2)OH framework. This in situ auto-reduction strategy may be extended to encapsulate various kinds of metal or alloy clusters/nanoparticles within amino-functioned metal-organic frameworks (MOFs) with superior properties and excellent performance.展开更多
Polysilicon films deposited by low-pressure chemical vapor deposition (LPCVD) exhibit large residual stress and stress gradient, depending on the deposition condition. An in situ growth method based on multilayer conc...Polysilicon films deposited by low-pressure chemical vapor deposition (LPCVD) exhibit large residual stress and stress gradient, depending on the deposition condition. An in situ growth method based on multilayer concept is presented to control the property for as-deposited polysilicon. A 3-μm thick polysilicon film with nine layers structure is demonstrated under the detailed analysis of multi-layer theory and material characteristic of polysilicon. The results show that a 3-μm-thick polysilicon film with 8-MPa overall residual tensile stress and 2.125-MPa/μm stress gradient through the film thickness is fabricated successfully.展开更多
A method is presented for in situ resolution calibration of multiple feedback interferometers(MFIs) using two lasers with di?erent feedback levels simultaneously. The laser with weak optical feedback level generates h...A method is presented for in situ resolution calibration of multiple feedback interferometers(MFIs) using two lasers with di?erent feedback levels simultaneously. The laser with weak optical feedback level generates half-wavelength optical fringes, whereas the laser with strong multiple feedback level generates optical nanofringes. By using this method, the number of displaced optical nano-fringes can be easily counted, and the resolution of the MFIs can be accurately determined. The integrated MFIs can be used to measure displacements and calibrate other displacement sensors.展开更多
Carbon nanotube （CNTs）/Fe-Ni/TiO2 nanocomposite photocatalysts have been synthesized by an in situ fluidized bed chemical vapor deposition （FBCVD） method. The composite photocatalysts were characterized by XRD, Ra...Carbon nanotube （CNTs）/Fe-Ni/TiO2 nanocomposite photocatalysts have been synthesized by an in situ fluidized bed chemical vapor deposition （FBCVD） method. The composite photocatalysts were characterized by XRD, Raman spectroscopy, BET, FESEM, TEM, UV-vis spectroscopy, and XPS. The results showed that the CNTs were grown in situ on the surface of TiO2. Fe（Ⅲ） in TiO2 showed no chemical changes in the growth of CNTs. Ni（Ⅱ） was partly reduced to metal Ni in the FBCVD process, and the metal Ni acted as a catalyst for the growth of CNTs. The photocatalytic activities of CNTs/Fe-Ni/TiO2 decreased with the rise of the FBCVD reaction temperature. For the sample synthesized at low FBCVD temperature （500 ℃）, more than 90% and nearly 50% of methylene blue were removed under UV irradiation in 180 min and under visible light irradiation in 300 min, respectively. The probable mechanism of synergistic enhancement of photocatalysis on the CNTs/Fe-Ni/TiO2 nanocomposite is proposed.展开更多
Soil erosion by snow or ice melt waterflow is an important type of soil erosion in many high-altitude and high-latitude regions and is further aggravated by climate warming.The snowmelt waterflow erosion process is af...Soil erosion by snow or ice melt waterflow is an important type of soil erosion in many high-altitude and high-latitude regions and is further aggravated by climate warming.The snowmelt waterflow erosion process is affected by soil freeze-thaws and is highly dynamically variable.In this study,a methodology was developed to conduct in situ field experiments to investigate the effects of the thawed depth of the frozen soil profile on snowmelt waterflow erosion.The method was implemented on an alpine meadow soil slope at an altitude of 3700 m on the northeastern Tibetan Plateau.The erosion experiments involved five thawed soil depths of 0,10,30(35),50,and 80(100)mm under two snowmelt waterflow rates(3 and 5 L/min).When the topsoil was fully frozen or shallow-thawed(≤10 mm),its hydrothermal and structural properties caused a significant lag in the initiation of runoff and delayed soil erosion in the initial stage.The runoff and sediment concentration curves for fully frozen and shallow-thawed soil showed two-stage patterns characteristic of a sediment supply limited in the early stage and subject to hydrodynamic-controlled processes in the later stage.However,this effect did not exist where the thawed soil depth was greater than 30 mm.The deep-thawed cases(≥30 mm)showed normal hydrograph and sedigraph patterns similar to those of the unfrozen soil.The findings of this study are important for understanding the erosion rates of partially thawed soil and for improving erosion simulations in cold regions.展开更多
Owing to their advantages,such as a high energy density,low operating potential,high abundance,and low cost,rechargeable silicon(Si)anode lithium-ion batteries(LIBs)have attracted considerable interest.Significant adv...Owing to their advantages,such as a high energy density,low operating potential,high abundance,and low cost,rechargeable silicon(Si)anode lithium-ion batteries(LIBs)have attracted considerable interest.Significant advancements in Si-based LIBs have been made over the past decade.Nevertheless,because the cycle instability is a crucial factor in the half/full-battery design and significantly affects the consumption of active components and the weight of the assembled battery,it has become a concern in recent years.This paper presents a thorough analysis of the recent developments in the enhancement methods for the stability of LIBs.Comprehensive in situ and operando characterizations are performed to thoroughly evaluate the electrochemical reactions,structural evolution,and degradation processes.Approaches for enhancing the cycle stability of Si anodes are systematically divided from a design perspective into several categories,such as the structural regulation,interfacial design,binder architecture,and electrolyte additives.The advantages and disadvantages of several methods are emphasized and thoroughly evaluated,offering insightful information for the logical design and advancement of cutting-edge solutions to address the deteriorating low-cycle stability of silicon-based LIBs.Finally,the conclusions and potential future research perspectives for promoting the cycling instability of silicon-based LIBs are presented.展开更多
基金supported by the National Natural Science Foundation of China(U21A20116).
文摘A metallurgical model for austenite coarsening in the coarse-grained heat-affected zone(CGHAZ)containing titanium nitride(TiN)precipitation was studied.Unlike traditional methods estimating pinning capability based on the precipitation size after welding,a proposed dissolution and coarsening model was applied to study the changes in TiN precipitation size and the associated pinning forces.The transmission electron microscope was used to analyze the size distribution of TiN particles before and after the welding thermal cycle.The size distribution showed a log-normal distribution before the thermal cycle.The prediction of post-thermal cycle size distributions with the proposed model was in agreement with the experimental results.Considering the short holding time at high temperature during welding,the thermodynamic stability conditions required for limiting grain size model cannot be achieved.A simple kinetic model for the prediction of austenite grain size in CGHAZ was established.Finally,the predicted austenite grain sizes agree better with experimental results than the conventional approach.
文摘H pylori is etiologically associated with gastritis, gas-tric and duodenal ulcers, gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. Eradicating H pylori may convert rapidly the outcome of related diseases with the use of more accurate diagnostic molecular tests. Indeed some of the tests cannot give the evidence of current infection; H pylori can be detected by noninvasive and invasive methods, the latter requiring an endoscopy. Eradication failure is a big problem in H pylori infection. Recently, clarithromycin resistance in H pylori strains is increasing and eradicati-on therapy of this bacterium is becoming more difficult. Molecular methods have frequently been applied besides phenotypic methods for susceptibility testing to detect clarithromycin resistance due to mutations in the 2143 and 2144 positions of 23S rRNA gene. Fluorescence in situ hybridization (FISH) method on paraffin embedded tissue is a rapid, accurate and cost-effective method for the detection of H pylori infection and to determine clarithromycin resistance within three hours according to the gold standards as a non-culture method. This method can also be applied to fresh biopsy samples and the isolated colonies from a culture of H pylori, detecting both the culturable bacillary forms and the coccoid forms of H pylori, besides the paraffin embedded tissue secti-ons. This technique is helpful for determining the bac-terial density and the results of treatment where clarith-romycin has been widely used in populations to increase the efficacy of the treatment and to clarify the treatment failure in vitro.
文摘The distribution of rDNA was visualized in interphase nuclei of tumor promoter treated human lymphocytes in comparison with the mltogen Phytoheamagglutinin (PHA) effects by using an in situ hybridization fluorescent method. The procedure involves biotinylated rDNA as the probe and FITC-avidin as detection system. Silver (Ag) staining was used to visualize nucleoli. In the interphase nuclei of most of the nonstimulated control lymphocytes, only one small Ag-stained nucleolus could be seen. The in situ hybridization, however, revealed one to several agglomerations of rDNA fluorescent spots. With tumor promoting herb extract WCE (40 μg/ml) or TPA (60 ng/ ml) treatment, the Interphase nucleoli increased slightly in number with the morphology alteration into larger, reticular or compact granular types. Ag-stained particles also increased in number. The number of the in situ hybridization rDNA fluorescent spots and dots increased markedly and largereticulate formations of numerous rDNA spots were seen. This phenomenum resembles to the changes in PHA stimulated lymphocytes. Statistic analysized data showed signifcant difference between control and drug- treated cells. These results indicate that transcriptionally activated rDNA and amplification of total rDNA was induced by the used tumor promoters.
文摘Agrobacterium-mediated gene transformation in Brassica crops is a time-con-suming and labor-cost method （tissue culture and plant regeneration） in a genotype-depen-dent way. Here we described a new method 7n situ pistil delivery （ISPDy method with no tissue culture and adaptive to three Brassica species. Briefly this method can be stated as placement of a liquid drop containing binary vector DNA onto the cut surface of emasculated and artificial pollinated Brassica stigma. Transformation rate （Basta-resistant seedlings per 100 pistils） of different species ranged from 0.4% to 16.3%. Factors affecting transforma-tion success included tinning and buffer type. PCR and Southern blot confirmed transgenic events. Reciprocal cross showed reporter gene steadily inherited in nuclear transformed pattern. GUS histochemical assay of transgenic immature seeds showed stained embroys and endosperm in the same seed, indicating DNA delivered through style and integrated into Brassica seed/genome after double fertilization.
基金supported by the National Natural Science Foundation of China(Grant Nos.:82073808,81872828,and 81573384).
文摘Covalent organic frameworks(COFs)are a novel type of crystalline porous organic polymer materials recently developed.It has several advantages in chromatographic separation field,such as high thermal stability,porosity,structural regularity,and large specific surface area.Here,a novel spherical COF 1,3,5-tris(4-aminophenyl)benzene(TAPB)and 2,5-bis(2-propyn-1-yloxy)-1,4-benzenedicarboxaldehyde(BPTA)was developed as an electrochromatographic stationary phase for capillary electrochromatography separation.The COF TAPB-BPTA modified capillary column was fabricated via a facile in situ growth method at room temperature.The characterization results of scanning electron microscopy(SEM),Fourier transform infrared(FT-IR)spectroscopy,and X-ray diffraction(XRD)confirmed that COF TAPB-BPTA were successfully modified onto the capillary inner surface.The electrochromatography separation performance of the COF TAPB-BPTA modified capillary was investigated.The prepared column demonstrated outstanding separation performance toward alkylbenzenes,phenols,and chlorobenzenes compounds.Furthermore,the baseline separations of non-steroidal anti-inflammatory drugs(NSAIDs)and parabens with good efficiency and high resolution were achieved.Also,the prepared column possessed satisfactory precision of the intra-day runs(n=5),inter-day runs(n=3),and parallel columns(n=3),and the relative standard deviations(RSDs)of the retention times of tested alkylbenzenes were all less than 2.58%.Thus,this new COF-based stationary phase shows tremendous application potential in chromatographic separation field.
基金Project(20376086)supported by the National Natural Science Foundation of ChinaProject(2005037700)supported by Postdoctora Science Foundation of China+2 种基金Project(07JJ3014)supported by Hunan Provincial Natural Science Foundation of ChinaProject(07A058)supported by Scientific Research Fund of Hunan Provincial Education DepartmentProject(2004107)supported by Postdoctoral Science Foundation of Central South University,China
文摘Li4Ti5O12 powders were prepared by so-gel method using tetrabutyl titanate,lithium acetate and absolute alcohol as starting materials.Li4Ti5O12-polyaniline(Li4Ti5O12-PAn)composite was prepared by in situ polymerization method using aniline, ammonium persulfate and hydrochloricarried as starting materials.Li4Ti5O12-PAn composite was characterized by X-ray diffractometry(XRD),infrared spectrum(IR)combined with electrochemical tests.The results show that the electrical conductivity is enhanced obviously due to the introduction of PAn to Li4Ti5O12.Li4Ti5O12-PAn composite exhibits better high-rate capability and cyclability than Li4Ti5O12.The composite can deliver a specific capacity of 191.3 and 148.9 mA·h/g,only 0.13%and 0.61%of the capacity is lose after being discharged 80 times at 0.1C and 2.0C,respectively.
基金supported by the National Key Research and Development Program of China(2016YFB0301100)the National Natural Science Foundation of China(51701029,51531002,51474043)+2 种基金China Postdoctoral Science Foundation Funded Project(2017M620410,2018T110942)the ChongqingPostdoctoral Scientific Research Foundation(Xm2017010)the Chongqing Research Program of Basic Research and Frontier Technology(cstc2016jcyjA0388,cstc2017jcyjBX0040)。
文摘In situ-grown Mg-Al layered double hydroxide(LDH)films were obtained on an anodized AZ31 substrate,with the immersion of sample in different concentrations of Al^(3+)solution.The structure,composition and morphology of LDH films were investigated by X-ray diffraction(XRD),Fourier transform infrared(FTIR)and scanning electronic microscopy(SEM),and the corrosion behavior of LDH films was further studied by electrochemical impedance spectroscopy(EIS).The influence of Al^(3+)concentration on the growth behavior of LDH was also discussed.The results indicated that the nest-like structure of MgAl-LDH film was composed of interconnected MgAl-LDH nanosheets.Besides,the LDH obtained in0.032 mol·L^(-1)Al^(3+)solution,possessing dense laminated structure,could effectively seal the porous surface of anodic oxide film.EIS results revealed that the samples coated with LDH films showed a higher electrochemical impedance,and thus,the corrosion resistance of samples coated with LDH films was signally improved compared with the anodized alloy.
基金financially supported by the National Funds for Distinguished Young Scientists (No. 61825503)the National Natural Science Foundation of China (Nos. 51902101, 61775101,61804082)+3 种基金the Youth Natural Science Foundation of Hunan Province (No. 2019JJ50044)Natural Science Foundation of Jiangsu Province (No. BK20201381)Science Foundation of Nanjing University of Posts and Telecommunications (No. NY219144)China Postdoctoral Science Foundation (Nos. 2020TQ0202, 2021M692161)。
文摘Molybdenum disulfide(MoS_(2)),a typical two-dimensional transition metallic layered material,attracts tremendous attentions in the electrochemical energy storage due to its excellent physicochemical properties.However,with the deepening of the research and exploration of the lithium storage mechanism of these advanced MoS_(2)-based anode materials,the complex reaction process influenced by internal and external factors hinders the exhaustive understanding of the lithium storage process.To design stable anode material with high performance,it is urgent to review the mechanisms of reported anode materials and summarize the related factors that influence the reaction processes.This review aims to dissect all possible side reactions during charging and discharging process,uncover internal and external factors inducing various anode reactions and finally put forward strategies of controlling high cycling capacity and super-stable lithium storage capability of MoS_(2).This review will be helpful to the design of MoS_(2)-based lithium-ion batteries(LIBs) with excellent cycle performance to enlarge the application fields of these advanced electrochemical energy storage devices.
基金Financial supports from the National Natural Science Foundation of China(Grant Nos.51579188 and 51409198)the National Basic Research Program of China(Grant No.2011CB013503)
文摘Numerous deep underground projects have been designed and constructed in China, which are beyond the current specifications in terms of scale and construction difficulty. The severe failure problems induced by high in situ stress, such as rockburst, spalling, damage of deep surrounding rocks, and timedependent damage, were observed during construction of these projects. To address these problems, the dynamic design method for deep hard rock tunnels is proposed based on the disintegration process of surrounding rocks using associated dynamic control theories and technologies. Seven steps are basically employed：（i） determination of design objective,（ii） characteristics of site, rock mass and project, and identification of constraint conditions,（iii） selection or development of global design strategy,（iv）determination of modeling method and software,（v） preliminary design,（vi） comprehensive integrated method and dynamic feedback analysis, and（vii） final design. This dynamic method was applied to the construction of the headrace tunnels at Jinping II hydropower station. The key technical issues encountered during the construction of deep hard rock tunnels, such as in situ stress distribution along the tunnels, mechanical properties and constitutive model of deep hard rocks, determination of mechanical parameters of surrounding rocks, stability evaluation of surrounding rocks, and optimization design of rock support and lining, have been adequately addressed. The proposed method and its application can provide guidance for deep underground projects characterized with similar geological conditions.
基金This work was supported by the Opening Project of the Key Laboratory of Green Chemistry of Sichuan Institutes of Higher Education(LZJ2002)the Open Project of Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province(CSPC2016-3-2).
文摘AgCl/Ti_(3)C_(2)@TiO_(2)ternary composites were prepared to form a heterojunction structure between AgCl and TiO_(2)and introduce Ti3C2 as a cocatalyst.The as-prepared AgCl/Ti_(3)C_(2)@TiO_(2)composites showed higher photocatalytic activity than pure AgCl and Ti_(3)C_(2)@TiO_(2)for photooxidation of a 1,4-dihydropyridine derivative(1,4-DHP)and tetracycline hydrochloride(TCH)under visible light irradiation(λ>400 nm).The photocatalytic activity of AgCl/Ti_(3)C_(2)@TiO_(2)composites depended on Ti_(3)C_(2)@TiO_(2)content,and the catalytic activity of the optimized samples were 6.9 times higher than that of pure AgCl for 1,4-DHP photodehydrogenation and 7.3 times higher than that of Ti_(3)C_(2)@TiO_(2)for TCH photooxidation.The increased photocatalytic activity was due to the formation of a heterojunction structure between AgCl and TiO_(2)and the introduction of Ti3C2 as a cocatalyst,which lowered the internal resistance,sped up the charge transfer,and increased the separation efficiency of photogenerated carries.Photogenerated holes and superoxide radical anions were the major active species in the photocatalytic process.
文摘Conservation of genetic diversity of forest tree species represents the foundation for sustainable forest management and preservation of natural structure of forest stands in Croatia. Diversity of geographical regions in Croatia has generated various ecological conditions and thus diverse forest communities which are directly affected by habitat degradation, various anthropogenic effects like pollution of air and water, excessive use of certain more valuable species of forest trees and by the increasing impact of global climatic changes. The need for conservation of genetic diversity is related to the species pertaining to social broadleaves—the prevailing species in terms of economic utilization as Pedunculate Oak (Quercus robur), Sessile Oak (Quercus petraea) and Common Beech (Fagus sylvatica). Among the conifers Silver Fir (Abies alba) is the most endangered species, with more than 70% of its population being seriously damaged. Other native coniferous species must be preserved from a decrease in genetic diversity as well. Conservation of the noble broadleaves should encompass a larger number of species from various genera (Fraxinus, Alnus, Ulmus, Prunus, Juglans, Castanea, Sorbus, Acer, Malus, Pyrus, Tilia). These are partially endangered because of their exposure to different pests and diseases, as well as by permanent exploitation due to their technical value. Changes in hydrological conditions of rivers have led difficulties in regeneration of the riparian forests and decreased the genetic variability of European Black and White Poplar in their habitats (Populus nigra, P. alba). In Croatia’s Adriatic coastal areas, there is a need for conservation of genetic resources of Dalmatian Black Pine (P. nigra ssp. dalmatica) and Mediterranean Oaks (Quercus ilex, Quercus pubescens). Conservation of genetic diversity of various forest tree species is conducted within the programmes that include in situ and ex situ methods with ensuring quality forest reproductive materials. In Croatia, a total of 125 seed stands have been selected, covering a total area of 3885.53 ha. The ex situ method is implemented by establishment of a total of 50 plots (clonal seed orchards, provenances and progeny trials, clonal archives), covering 114.85 ha.
基金We acknowledge the financial supports from the National Natural Science Foundation of China(No.51802015)Fundamental Research Funds for the Central Universities(No.FRF-TP-20-005A3)Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities)(No.FRF-IDRY-19-020).
文摘Efficient hydrogen production via photocatalysis with high utilization efficiency of Pt cocatalyst is of great importance for sustainable development. In this work, we report an in situ auto-reduction strategy to encapsulate highly dispersed Pt clusters inside the cages of MIL-125-NH_(2). The amino groups in MIL-125-NH_(2) first react with formaldehyde to form reducing groups (i.e.,–NH-CH_(2)OH), which can in situ auto-reduce the confined Pt^(2+) ions to ultrasmall Pt clusters within the cavities. With optimized Pt content, photocatalytic H_(2) production over the obtained Pt(1.5)/MIL-125-NH-CH_(2)OH catalyst with 1.43 wt.% Pt loading achieved as high as 4,496.4 µmol·g^(-1)·h^(-1) under visible light (λ > 420 nm) due to the facilitated transfer and separation of the photo-induced charger carriers arising from the synergetic effects between highly dispersed Pt clusters and MIL-125-NH-CH_(2)OH framework. This in situ auto-reduction strategy may be extended to encapsulate various kinds of metal or alloy clusters/nanoparticles within amino-functioned metal-organic frameworks (MOFs) with superior properties and excellent performance.
文摘Polysilicon films deposited by low-pressure chemical vapor deposition (LPCVD) exhibit large residual stress and stress gradient, depending on the deposition condition. An in situ growth method based on multilayer concept is presented to control the property for as-deposited polysilicon. A 3-μm thick polysilicon film with nine layers structure is demonstrated under the detailed analysis of multi-layer theory and material characteristic of polysilicon. The results show that a 3-μm-thick polysilicon film with 8-MPa overall residual tensile stress and 2.125-MPa/μm stress gradient through the film thickness is fabricated successfully.
基金supported by the Key Project of the National Natural Science Foundation of China(Nos.51375262,60827006,and 60723004)the Scientific and Technological Achievements,Transformation and Industrialization project by the Beijing Municipal Education Commission,and the Scholarship Award for Excellent Doctoral Students granted by the Ministry of Education
文摘A method is presented for in situ resolution calibration of multiple feedback interferometers(MFIs) using two lasers with di?erent feedback levels simultaneously. The laser with weak optical feedback level generates half-wavelength optical fringes, whereas the laser with strong multiple feedback level generates optical nanofringes. By using this method, the number of displaced optical nano-fringes can be easily counted, and the resolution of the MFIs can be accurately determined. The integrated MFIs can be used to measure displacements and calibrate other displacement sensors.
基金supported by the Special Projects for Nanotechnology of Shanghai(1052mm02400)the National Nature Science Foundation of China(20925621)
文摘Carbon nanotube （CNTs）/Fe-Ni/TiO2 nanocomposite photocatalysts have been synthesized by an in situ fluidized bed chemical vapor deposition （FBCVD） method. The composite photocatalysts were characterized by XRD, Raman spectroscopy, BET, FESEM, TEM, UV-vis spectroscopy, and XPS. The results showed that the CNTs were grown in situ on the surface of TiO2. Fe（Ⅲ） in TiO2 showed no chemical changes in the growth of CNTs. Ni（Ⅱ） was partly reduced to metal Ni in the FBCVD process, and the metal Ni acted as a catalyst for the growth of CNTs. The photocatalytic activities of CNTs/Fe-Ni/TiO2 decreased with the rise of the FBCVD reaction temperature. For the sample synthesized at low FBCVD temperature （500 ℃）, more than 90% and nearly 50% of methylene blue were removed under UV irradiation in 180 min and under visible light irradiation in 300 min, respectively. The probable mechanism of synergistic enhancement of photocatalysis on the CNTs/Fe-Ni/TiO2 nanocomposite is proposed.
基金This study is financially supported by the National Natural Science Foundation of China(Grant No.42271142,42101130)the Belt and Road Special Foundation of the State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering(2020490311).
文摘Soil erosion by snow or ice melt waterflow is an important type of soil erosion in many high-altitude and high-latitude regions and is further aggravated by climate warming.The snowmelt waterflow erosion process is affected by soil freeze-thaws and is highly dynamically variable.In this study,a methodology was developed to conduct in situ field experiments to investigate the effects of the thawed depth of the frozen soil profile on snowmelt waterflow erosion.The method was implemented on an alpine meadow soil slope at an altitude of 3700 m on the northeastern Tibetan Plateau.The erosion experiments involved five thawed soil depths of 0,10,30(35),50,and 80(100)mm under two snowmelt waterflow rates(3 and 5 L/min).When the topsoil was fully frozen or shallow-thawed(≤10 mm),its hydrothermal and structural properties caused a significant lag in the initiation of runoff and delayed soil erosion in the initial stage.The runoff and sediment concentration curves for fully frozen and shallow-thawed soil showed two-stage patterns characteristic of a sediment supply limited in the early stage and subject to hydrodynamic-controlled processes in the later stage.However,this effect did not exist where the thawed soil depth was greater than 30 mm.The deep-thawed cases(≥30 mm)showed normal hydrograph and sedigraph patterns similar to those of the unfrozen soil.The findings of this study are important for understanding the erosion rates of partially thawed soil and for improving erosion simulations in cold regions.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.U22A20420,22078029,22208029,and 52203292)Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX23_3027)the“333 high-level talent training project”young and middle-aged leading talent project of Jiangsu Province.
文摘Owing to their advantages,such as a high energy density,low operating potential,high abundance,and low cost,rechargeable silicon(Si)anode lithium-ion batteries(LIBs)have attracted considerable interest.Significant advancements in Si-based LIBs have been made over the past decade.Nevertheless,because the cycle instability is a crucial factor in the half/full-battery design and significantly affects the consumption of active components and the weight of the assembled battery,it has become a concern in recent years.This paper presents a thorough analysis of the recent developments in the enhancement methods for the stability of LIBs.Comprehensive in situ and operando characterizations are performed to thoroughly evaluate the electrochemical reactions,structural evolution,and degradation processes.Approaches for enhancing the cycle stability of Si anodes are systematically divided from a design perspective into several categories,such as the structural regulation,interfacial design,binder architecture,and electrolyte additives.The advantages and disadvantages of several methods are emphasized and thoroughly evaluated,offering insightful information for the logical design and advancement of cutting-edge solutions to address the deteriorating low-cycle stability of silicon-based LIBs.Finally,the conclusions and potential future research perspectives for promoting the cycling instability of silicon-based LIBs are presented.
