Pitch produced by the lique-faction of coal was divided into two frac-tions:soluble in toluene(TS)and insol-uble in toluene but soluble in pyridine(TI-PS),and their differences in molecu-lar structure and oxidation ac...Pitch produced by the lique-faction of coal was divided into two frac-tions:soluble in toluene(TS)and insol-uble in toluene but soluble in pyridine(TI-PS),and their differences in molecu-lar structure and oxidation activity were studied.Several different carbon materi-als were produced from them by oxida-tion in air(350℃,300 mL/min)fol-lowed by carbonization(1000℃ in Ar),and the effect of the cross-linked structure on their structure and sodium storage properties was investigated.The results showed that the two pitch fractions were obviously different after the air oxidation.The TS fraction with a low degree of condensation and abundant side chains had a stronger oxidation activity and thus introduced more cross-linked oxygen-containing functional groups C(O)―O which prevented carbon layer rearrangement during the carbonization.As a result,a disordered hard carbon with more defects was formed,which improved the electrochemical performance.Therefore,the carbon materials derived from TS(O-TS-1000)had an obvious disordered structure and a larger layer spacing,giving them better sodium storage perform-ance than those derived from the TI-PS fraction(O-TI-PS-1000).The specific capacity of O-TS-1000 was about 250 mAh/g at 20 mA/g,which was 1.67 times higher than that of O-TI-PS-1000(150 mAh/g).展开更多
Six coordination polymers based on 9,10-di(pyridine-4-yl)-anthracene(DPA)and 1,6-di(1H-imidazol-1-yl)pyrene(DIP)were obtained by solvothermal reactions.{[Zn(DPA)Cl_(2)]·DMF·2H_(2)O}n(1)and{[Zn_(1.5)(DPA)_(1....Six coordination polymers based on 9,10-di(pyridine-4-yl)-anthracene(DPA)and 1,6-di(1H-imidazol-1-yl)pyrene(DIP)were obtained by solvothermal reactions.{[Zn(DPA)Cl_(2)]·DMF·2H_(2)O}n(1)and{[Zn_(1.5)(DPA)_(1.5)Cl_(3)]·5H_(2)O}n(2)are framework isomers,which both contain zigzag chains formed by DPA,Zn^(2+),and Cl-.The zigzag chains in 1 are further assembled by C—H…Cl interactions into layers,and these layers exhibit two different orientations,displaying a rare 2D to 3D interpenetration mode.The zigzag chains in 2 are parallelly arranged.{[Zn_(3)(DPA)_(3)Br_(6)]·2DMF·_(1.5)H_(2)O}n(3)is isostructural to 2.3 was obtained using ZnBr_(2)instead of ZnCl_(2).[M(DPA)(formate)_(2)(H_(2)O)_(2)]n[M=Co(4),Cu(5)]are isostructural,contain chain structures formed by DPA,Cu^(2+)/Co^(2+),and for-mate ions,which were formed in situ in the solvothermal reaction.{[Zn(DIP)_(2)Cl]ClO_(4)}n(6)contains a layer structure formed by DIP and Zn^(2+).Free DPA and DIP ligands exhibited high fluorescence at room temperature,and coordina-tion polymers 3 and 6 displayed enhanced fluorescent emissions.展开更多
OBJECTIVE To investigate enhanced immune function of methionine encephalin(MENK)and its anti-tumor mechanism in CT26 colon cancer mouse model.METHODS 3×10~6CT26 cells were implanted subcutaneously in BALB/c mice....OBJECTIVE To investigate enhanced immune function of methionine encephalin(MENK)and its anti-tumor mechanism in CT26 colon cancer mouse model.METHODS 3×10~6CT26 cells were implanted subcutaneously in BALB/c mice.Four days after,MENK was peritoneally administrated at the concentration of 20 mg·kg^(-1) for 14 d.The percentage of MDSCs in bone marrow,spleen,blood,tumor and liver were detected by flow cytometry.Non-esterified fatty acid(NEFA),triglycerides(TG)and total cholesterol(T-CHO)in liver homogenate were tested by a NEFA test kit,a TG test kit and a T-CHO test kit respectively.qRT-PCR and Western blot were used to measure m RNA and protein levels of inflammation-,glycometabolsim-and lipometabolsim-associated indexes in liver.RESULTS MENK decreased percentages of MDSCs in bone marrow,spleen,blood and tumor in colon cancer mice.MENK-treated mice displayed elevated ratio of CD4^+T and CD8^+T cells in spleen as well as increased T and B lymphocytes proliferation.Meanwhile,MENK also ameliorated liver damage reflected by lower levels of GPT and GOT in serum and reduced risks of cancer-associated index including inflammation,high lipid and high glucose.Furthermore,MENK lowered down the levels of NEFA,TG and T-CHO in liver homogenate.MENK treatment decreased expression of p-STAT3,increased expression of p-AKT,IRS1 and Glut4 at protein level as well as reduced lipogenesis-associated genes and elevated glycolysis-associated genes in liver of tumor bearing mice.Also,abated expression of genes associated with MDSCs generation(M-CSF,GM-CSF,IL-6,IL^(-1)β)and migration(S100A9,KC)was observed within shrunken subcutaneous tumor by MENK intervention.CONCLUSION MENK has the ability to strength immune function against colon cancer by reducing MDSCs and improving liver metabolism.展开更多
We report five coordination polymers(CPs)based on fluorescent ligands[1,6-di(1H-imidazol-1-yl)pyrene(dip),9,10-di(1H-imidazol-1-yl)anthracene(dia)]and anionic ligands[cyclohexane-1,4-dicarboxylic acid(H_(2)cda),campho...We report five coordination polymers(CPs)based on fluorescent ligands[1,6-di(1H-imidazol-1-yl)pyrene(dip),9,10-di(1H-imidazol-1-yl)anthracene(dia)]and anionic ligands[cyclohexane-1,4-dicarboxylic acid(H_(2)cda),camphoric acid(H_(2)cpa)].In[Cd(dip)(cda)]·4H_(2)O}_(n)(1),the Cd^(2+)ions,acting as tetrahedral nodes,are linked by dipand cda^(2-)ligands with four Cd^(2+)ions into five-fold interpenetrating network array of topology of dia.In{[Cd(dip)(cpa)]·4H_(2)O}_(n)(2),the Cd^(2+)ions,acting as a 4-connector,are linked by cpa^(2-)and dip ligands into a 3D framework ofcds topology.In{[Ni(dia)_(2)Cl_(2)]·DMF}_(n)(3),the Ni^(2+)ion is linked by four dia ligands into a layer structure,and 1Dchannels of a cross-section of 1.35 nm×0.96 nm are formed.In{[Cd(dia)_(2)(H_(2)O)_(2)](NO_(3))_(2)·2DMSO}n(4),the dia ligandsconnected Cd^(2+)ions into a 2D layer,and 1D channels are formed between adjacent layers with a cross-section of0.87 nm×0.43 nm.In[Zn(dip)Cl_(2)]_(n)(5),the Zn^(2+)ion is linked by dip ligands into an infinite 1D chain.The infrared,thermal gravimetric,and fluorescent emission data were collected and analyzed for these coordination polymers.CCDC:2356055,1;2440075,2;2356057,3;2356057,4;2356059,5.展开更多
The selective hydrogenation ofα,β-unsaturated aldehydes/ketones enables precise control over product structures and properties by regulating hydrogen transport pathways and bond cleavage sequences to selectively red...The selective hydrogenation ofα,β-unsaturated aldehydes/ketones enables precise control over product structures and properties by regulating hydrogen transport pathways and bond cleavage sequences to selectively reduce C=C or C=O bonds while preserving other functional groups within the molecule.This approach serves as a critical strategy for the directional synthesis of high-value molecules.However,achieving such selectivity remains challenging due to the thermodynamic equilibrium and kinetic competition between C=O and C=C bonds inα,β-unsaturated systems.Consequently,constructing precisely targeted catalytic systems is essential to overcome these limitations,offering both fundamental scientific significance and industrial application potential.Metal-organic frameworks(MOFs)and their derivatives have emerged as innovative platforms for designing such systems,owing to their programmable topology,tunable pore microenvironments,spatially controllable active sites,and modifiable electronic structures.This review systematically summarizes the research progress of MOF-based catalysts for selec-tive hydrogenation ofα,β-unsaturated aldehydes/ketones in the last decade,with emphasis on the design strategy,conformational relationship,and catalytic mechanism,aiming to provide new ideas for the design of targeted catalyt-ic systems for the selective hydrogenation ofα,β-unsaturated aldehydes/ketones.展开更多
To investigate the effect of rail pad viscoelasticity on vehicle-track-bridge coupled vibration,the fractional Voigt and Maxwell model in parallel(FVMP)was used to characterize the viscoelastic properties of the rail ...To investigate the effect of rail pad viscoelasticity on vehicle-track-bridge coupled vibration,the fractional Voigt and Maxwell model in parallel(FVMP)was used to characterize the viscoelastic properties of the rail pad based on dynamic performance test results.The FVMP model was then incorporated into the vehicle-track-bridge nonlinear coupled model,and its dynamic response was solved using a cross-iteration algorithm with a relaxation factor.Results indicate that the nonlinear coupled model achieves good convergence when the time step is less than 0.001 s,with the cross-iteration algorithm adjusting the wheel-rail force.In particular,the best convergence is achieved when the relaxation factor is within the range of 0.3-0.5.The FVMP model effectively characterizes the viscoelasticity of rail pads across a temperature range of±20℃and a frequency range of 1-1000 Hz.The viscoelasticity of rail pads significantly affects high-frequency vibrations in the coupled system,particularly around 50 Hz,corresponding to the wheel-rail coupled resonance range.Considering rail pad viscoelasticity is essential for accurately predicting track structure vibrations.展开更多
Cotton plays a crucial role in shaping Indian economy and rural livelihoods.The cotton crop is prone to numerous insect pests,necessitating insecticidal application,which increases production costs.The advent of the e...Cotton plays a crucial role in shaping Indian economy and rural livelihoods.The cotton crop is prone to numerous insect pests,necessitating insecticidal application,which increases production costs.The advent of the expression of Bacillus thuringiensis(Bt)insecticidal protein in cotton has significantly reduced the burden of pest without compromising environmental or human health.After the introduction of transgenic cotton,the cultivated area expanded to 22 million hectares,with a 64% increase in adoption by farmers worldwide.Currently,Bt cotton accounts for 93% of the cultivated cotton area in India.However,extensive use of Bt cotton has accelerated resistance development in pests like the pink bollworm.Furthermore,the overreliance on Bt cotton has reduced the use of broad-spectrum pesticides,favouring the emergence of secondary pests with significant challenges.This emphasizes the urgent necessity for developing novel pest management strategies.The high-dose and refuge strategy was initially effective for managing pest resistance in Bt cotton,but its implementation in India faced challenges due to misunderstandings about the use of non-Bt refuge crops.Although gene pyramiding was introduced as a solution,combining mono toxin also led to instances of cross-resistance.Therefore,there is a need for further exploration of biotechnological approaches to manage insect resistance in Bt cotton.Advanced biotechnological strategies,such as sterile insect release,RNA interference(RNAi)-mediated gene silencing,stacking Bt with RNAi,and genome editing using clustered regularly interspaced short palindromic repeats/CRISPR-associated protein(CRISPR-Cas),offer promising tools for identifying and managing resistance genes in insects.Additionally,CRISPR-mediated gene drives and the development of novel biopesticides present potential avenues for effective pest management in cotton cultivation.These innovative approaches could significantly enhance the sustainability and efficacy of pest resistance management in Bt cotton.展开更多
This study presents the synthesis of three dinuclear cobalt complexes based on three imine derivatives:bis-[4-(2-pyridylmethyleneamino)-phenyl]thioether(L1),bis-[4-(2-pyridylmethyleneamino)-phenyl]ether(L2),and bis-[4...This study presents the synthesis of three dinuclear cobalt complexes based on three imine derivatives:bis-[4-(2-pyridylmethyleneamino)-phenyl]thioether(L1),bis-[4-(2-pyridylmethyleneamino)-phenyl]ether(L2),and bis-[4-(2-pyridylmethyleneamino)-phenyl]methane(L3).Single-crystal X-ray diffraction analysis reveals that the complexes[Co_(2)(L1)3](ClO_(4))4·2CH_(3)CN(1),[Co_(2)(L2)3](ClO_(4))4·2CH_(3)OH(2),and[Co_(2)(L3)3](ClO_(4))4·2CH_(3)OH(3)all exhibit a dinuclear structure.Magnetic test results show that complex 3 exhibited irreversible SCO behavior induced by loss of solvent at 300 K,with the average Co-N bond length increasing from 0.2139(3)to 0.2153(3)nm.Meanwhile,the desolvated complex 3 exhibited paramagnetic behavior similar to that of complexes 1 and 2.Variable-temperature UV-Vis spectroscopic studies also indicate that complex 3 undergoes a solvent-loss-induced spin-state transition.CCDC:2347354,1(120 K);2347355,2(120 K);2347356,3(120 K);2347357,3(400 K).展开更多
In this paper,we survey some recent progress in the study of time fractional equations and its interplay with anomalous sub-diffusions,with some improvements and extensions.
The mass spectrometric fragmentation of TMS derivatives of sterols was studied and analyzed based on the mass spectrometry of the TMS derivatives of standards.The double bond numbers and the degree of the methylize,al...The mass spectrometric fragmentation of TMS derivatives of sterols was studied and analyzed based on the mass spectrometry of the TMS derivatives of standards.The double bond numbers and the degree of the methylize,alkylize and the related position in the sterol nucleus and the side chains were confirmed by the characteristic ions.Total lipids were extracted using Bligh-Dyer method.Sterols were isolated by solvent partition with chloroform-hexane(1 ∶4,by volume),derivated by BSTFA,and analyzed by GC-MS.The regular pattern was used for identifying the sterols in a dinoflagellate from the Symbodinium sp.展开更多
汽车悬架控制系统是一个由较多非线性因素共同作用的复杂系统,针对传统PID控制效果不理想的问题,通过数值拟合的方式引入弹簧与阻尼等非线性影响因素,建立1/4汽车悬架非线性动力学模型,借鉴免疫反馈原理,结合积分控制的规律,提出一种模...汽车悬架控制系统是一个由较多非线性因素共同作用的复杂系统,针对传统PID控制效果不理想的问题,通过数值拟合的方式引入弹簧与阻尼等非线性影响因素,建立1/4汽车悬架非线性动力学模型,借鉴免疫反馈原理,结合积分控制的规律,提出一种模糊免疫PID(proportion integral derivative)控制方法,并利用免疫进化算法进行参数优化设计。仿真结果表明,该方法在汽车非线性悬架控制系统中可行且有效,其控制器性能也优于常规的PID控制器,具有更好的响应特性,同时也提高了汽车的操作稳定性和乘坐舒适性。展开更多
Our understanding of solid earth is from the surface, but the depth we can reach is very limited. So, most of the interpretations of geological processes and mechanisms extrapolated from all kinds of the surface pheno...Our understanding of solid earth is from the surface, but the depth we can reach is very limited. So, most of the interpretations of geological processes and mechanisms extrapolated from all kinds of the surface phenomena is greatly uncertain. Recently many researchers concentrate their efforts to the geological and geophysical studying of the deep processes of the solid earth. The International Lithosphere Project (ILP) started in 1981 now is also a frontier field. One of the concentrations of this project is the 3\|D structure, tectonic evolution and the dynamic models of lithosphere\|asthenosphere system (Li Xiaobo etc., 1997). The studying of the igneous rocks and bearing deep\|seated xenoliths, as one of the effective methods probing the structure and evolution of the lithosphere, plays a very important role in these aspects (Deng Jinfu et al., 1996; Lu Fengxiang, 1997).Commonly, magmas come to the surface in great speed and the covering lithosphere should be relatively thinner. For example, the thickness of the lithosphere in East China is about 60～80km in the era when the volcanoes erupted (Deng Jinfu et al. 1994). Recently, many deep\|seated xenoliths were found in several localities of southwest Tianshan (Han Baofu et al., 1998). But in Qinghai—Xizang plateau, “So far no any xenoliths of mantle rocks as peridotites, lherzolites and harzburgites and high pressure granulites were found (Deng Wanming et al., 1997)”.. But in the fieldwork of 1998 we find some deep\|seated xenoliths in Cenozoic basaltic rocks in Kangxiwa region, West Kunlun, China. This work is a part of the project “XinJiang DuShanZi—QuanShuiGou transect” managed by academician Xiao Xuchang.展开更多
文摘Pitch produced by the lique-faction of coal was divided into two frac-tions:soluble in toluene(TS)and insol-uble in toluene but soluble in pyridine(TI-PS),and their differences in molecu-lar structure and oxidation activity were studied.Several different carbon materi-als were produced from them by oxida-tion in air(350℃,300 mL/min)fol-lowed by carbonization(1000℃ in Ar),and the effect of the cross-linked structure on their structure and sodium storage properties was investigated.The results showed that the two pitch fractions were obviously different after the air oxidation.The TS fraction with a low degree of condensation and abundant side chains had a stronger oxidation activity and thus introduced more cross-linked oxygen-containing functional groups C(O)―O which prevented carbon layer rearrangement during the carbonization.As a result,a disordered hard carbon with more defects was formed,which improved the electrochemical performance.Therefore,the carbon materials derived from TS(O-TS-1000)had an obvious disordered structure and a larger layer spacing,giving them better sodium storage perform-ance than those derived from the TI-PS fraction(O-TI-PS-1000).The specific capacity of O-TS-1000 was about 250 mAh/g at 20 mA/g,which was 1.67 times higher than that of O-TI-PS-1000(150 mAh/g).
文摘Six coordination polymers based on 9,10-di(pyridine-4-yl)-anthracene(DPA)and 1,6-di(1H-imidazol-1-yl)pyrene(DIP)were obtained by solvothermal reactions.{[Zn(DPA)Cl_(2)]·DMF·2H_(2)O}n(1)and{[Zn_(1.5)(DPA)_(1.5)Cl_(3)]·5H_(2)O}n(2)are framework isomers,which both contain zigzag chains formed by DPA,Zn^(2+),and Cl-.The zigzag chains in 1 are further assembled by C—H…Cl interactions into layers,and these layers exhibit two different orientations,displaying a rare 2D to 3D interpenetration mode.The zigzag chains in 2 are parallelly arranged.{[Zn_(3)(DPA)_(3)Br_(6)]·2DMF·_(1.5)H_(2)O}n(3)is isostructural to 2.3 was obtained using ZnBr_(2)instead of ZnCl_(2).[M(DPA)(formate)_(2)(H_(2)O)_(2)]n[M=Co(4),Cu(5)]are isostructural,contain chain structures formed by DPA,Cu^(2+)/Co^(2+),and for-mate ions,which were formed in situ in the solvothermal reaction.{[Zn(DIP)_(2)Cl]ClO_(4)}n(6)contains a layer structure formed by DIP and Zn^(2+).Free DPA and DIP ligands exhibited high fluorescence at room temperature,and coordina-tion polymers 3 and 6 displayed enhanced fluorescent emissions.
基金supported by National Natural Science Foundation of China(81673440 and 81473585)
文摘OBJECTIVE To investigate enhanced immune function of methionine encephalin(MENK)and its anti-tumor mechanism in CT26 colon cancer mouse model.METHODS 3×10~6CT26 cells were implanted subcutaneously in BALB/c mice.Four days after,MENK was peritoneally administrated at the concentration of 20 mg·kg^(-1) for 14 d.The percentage of MDSCs in bone marrow,spleen,blood,tumor and liver were detected by flow cytometry.Non-esterified fatty acid(NEFA),triglycerides(TG)and total cholesterol(T-CHO)in liver homogenate were tested by a NEFA test kit,a TG test kit and a T-CHO test kit respectively.qRT-PCR and Western blot were used to measure m RNA and protein levels of inflammation-,glycometabolsim-and lipometabolsim-associated indexes in liver.RESULTS MENK decreased percentages of MDSCs in bone marrow,spleen,blood and tumor in colon cancer mice.MENK-treated mice displayed elevated ratio of CD4^+T and CD8^+T cells in spleen as well as increased T and B lymphocytes proliferation.Meanwhile,MENK also ameliorated liver damage reflected by lower levels of GPT and GOT in serum and reduced risks of cancer-associated index including inflammation,high lipid and high glucose.Furthermore,MENK lowered down the levels of NEFA,TG and T-CHO in liver homogenate.MENK treatment decreased expression of p-STAT3,increased expression of p-AKT,IRS1 and Glut4 at protein level as well as reduced lipogenesis-associated genes and elevated glycolysis-associated genes in liver of tumor bearing mice.Also,abated expression of genes associated with MDSCs generation(M-CSF,GM-CSF,IL-6,IL^(-1)β)and migration(S100A9,KC)was observed within shrunken subcutaneous tumor by MENK intervention.CONCLUSION MENK has the ability to strength immune function against colon cancer by reducing MDSCs and improving liver metabolism.
文摘We report five coordination polymers(CPs)based on fluorescent ligands[1,6-di(1H-imidazol-1-yl)pyrene(dip),9,10-di(1H-imidazol-1-yl)anthracene(dia)]and anionic ligands[cyclohexane-1,4-dicarboxylic acid(H_(2)cda),camphoric acid(H_(2)cpa)].In[Cd(dip)(cda)]·4H_(2)O}_(n)(1),the Cd^(2+)ions,acting as tetrahedral nodes,are linked by dipand cda^(2-)ligands with four Cd^(2+)ions into five-fold interpenetrating network array of topology of dia.In{[Cd(dip)(cpa)]·4H_(2)O}_(n)(2),the Cd^(2+)ions,acting as a 4-connector,are linked by cpa^(2-)and dip ligands into a 3D framework ofcds topology.In{[Ni(dia)_(2)Cl_(2)]·DMF}_(n)(3),the Ni^(2+)ion is linked by four dia ligands into a layer structure,and 1Dchannels of a cross-section of 1.35 nm×0.96 nm are formed.In{[Cd(dia)_(2)(H_(2)O)_(2)](NO_(3))_(2)·2DMSO}n(4),the dia ligandsconnected Cd^(2+)ions into a 2D layer,and 1D channels are formed between adjacent layers with a cross-section of0.87 nm×0.43 nm.In[Zn(dip)Cl_(2)]_(n)(5),the Zn^(2+)ion is linked by dip ligands into an infinite 1D chain.The infrared,thermal gravimetric,and fluorescent emission data were collected and analyzed for these coordination polymers.CCDC:2356055,1;2440075,2;2356057,3;2356057,4;2356059,5.
文摘The selective hydrogenation ofα,β-unsaturated aldehydes/ketones enables precise control over product structures and properties by regulating hydrogen transport pathways and bond cleavage sequences to selectively reduce C=C or C=O bonds while preserving other functional groups within the molecule.This approach serves as a critical strategy for the directional synthesis of high-value molecules.However,achieving such selectivity remains challenging due to the thermodynamic equilibrium and kinetic competition between C=O and C=C bonds inα,β-unsaturated systems.Consequently,constructing precisely targeted catalytic systems is essential to overcome these limitations,offering both fundamental scientific significance and industrial application potential.Metal-organic frameworks(MOFs)and their derivatives have emerged as innovative platforms for designing such systems,owing to their programmable topology,tunable pore microenvironments,spatially controllable active sites,and modifiable electronic structures.This review systematically summarizes the research progress of MOF-based catalysts for selec-tive hydrogenation ofα,β-unsaturated aldehydes/ketones in the last decade,with emphasis on the design strategy,conformational relationship,and catalytic mechanism,aiming to provide new ideas for the design of targeted catalyt-ic systems for the selective hydrogenation ofα,β-unsaturated aldehydes/ketones.
基金Project(2023ZDZX0008)supported by the Sichuan Major Science and Technology Project,ChinaProject(52308468)supported by the National Natural Science Foundation of ChinaProject(2022JBQY009)supported by the Fundamental Research Funds for the Central Universities(Science and Technology Leading Talent Team Project),China。
文摘To investigate the effect of rail pad viscoelasticity on vehicle-track-bridge coupled vibration,the fractional Voigt and Maxwell model in parallel(FVMP)was used to characterize the viscoelastic properties of the rail pad based on dynamic performance test results.The FVMP model was then incorporated into the vehicle-track-bridge nonlinear coupled model,and its dynamic response was solved using a cross-iteration algorithm with a relaxation factor.Results indicate that the nonlinear coupled model achieves good convergence when the time step is less than 0.001 s,with the cross-iteration algorithm adjusting the wheel-rail force.In particular,the best convergence is achieved when the relaxation factor is within the range of 0.3-0.5.The FVMP model effectively characterizes the viscoelasticity of rail pads across a temperature range of±20℃and a frequency range of 1-1000 Hz.The viscoelasticity of rail pads significantly affects high-frequency vibrations in the coupled system,particularly around 50 Hz,corresponding to the wheel-rail coupled resonance range.Considering rail pad viscoelasticity is essential for accurately predicting track structure vibrations.
文摘Cotton plays a crucial role in shaping Indian economy and rural livelihoods.The cotton crop is prone to numerous insect pests,necessitating insecticidal application,which increases production costs.The advent of the expression of Bacillus thuringiensis(Bt)insecticidal protein in cotton has significantly reduced the burden of pest without compromising environmental or human health.After the introduction of transgenic cotton,the cultivated area expanded to 22 million hectares,with a 64% increase in adoption by farmers worldwide.Currently,Bt cotton accounts for 93% of the cultivated cotton area in India.However,extensive use of Bt cotton has accelerated resistance development in pests like the pink bollworm.Furthermore,the overreliance on Bt cotton has reduced the use of broad-spectrum pesticides,favouring the emergence of secondary pests with significant challenges.This emphasizes the urgent necessity for developing novel pest management strategies.The high-dose and refuge strategy was initially effective for managing pest resistance in Bt cotton,but its implementation in India faced challenges due to misunderstandings about the use of non-Bt refuge crops.Although gene pyramiding was introduced as a solution,combining mono toxin also led to instances of cross-resistance.Therefore,there is a need for further exploration of biotechnological approaches to manage insect resistance in Bt cotton.Advanced biotechnological strategies,such as sterile insect release,RNA interference(RNAi)-mediated gene silencing,stacking Bt with RNAi,and genome editing using clustered regularly interspaced short palindromic repeats/CRISPR-associated protein(CRISPR-Cas),offer promising tools for identifying and managing resistance genes in insects.Additionally,CRISPR-mediated gene drives and the development of novel biopesticides present potential avenues for effective pest management in cotton cultivation.These innovative approaches could significantly enhance the sustainability and efficacy of pest resistance management in Bt cotton.
文摘This study presents the synthesis of three dinuclear cobalt complexes based on three imine derivatives:bis-[4-(2-pyridylmethyleneamino)-phenyl]thioether(L1),bis-[4-(2-pyridylmethyleneamino)-phenyl]ether(L2),and bis-[4-(2-pyridylmethyleneamino)-phenyl]methane(L3).Single-crystal X-ray diffraction analysis reveals that the complexes[Co_(2)(L1)3](ClO_(4))4·2CH_(3)CN(1),[Co_(2)(L2)3](ClO_(4))4·2CH_(3)OH(2),and[Co_(2)(L3)3](ClO_(4))4·2CH_(3)OH(3)all exhibit a dinuclear structure.Magnetic test results show that complex 3 exhibited irreversible SCO behavior induced by loss of solvent at 300 K,with the average Co-N bond length increasing from 0.2139(3)to 0.2153(3)nm.Meanwhile,the desolvated complex 3 exhibited paramagnetic behavior similar to that of complexes 1 and 2.Variable-temperature UV-Vis spectroscopic studies also indicate that complex 3 undergoes a solvent-loss-induced spin-state transition.CCDC:2347354,1(120 K);2347355,2(120 K);2347356,3(120 K);2347357,3(400 K).
文摘In this paper,we survey some recent progress in the study of time fractional equations and its interplay with anomalous sub-diffusions,with some improvements and extensions.
文摘The mass spectrometric fragmentation of TMS derivatives of sterols was studied and analyzed based on the mass spectrometry of the TMS derivatives of standards.The double bond numbers and the degree of the methylize,alkylize and the related position in the sterol nucleus and the side chains were confirmed by the characteristic ions.Total lipids were extracted using Bligh-Dyer method.Sterols were isolated by solvent partition with chloroform-hexane(1 ∶4,by volume),derivated by BSTFA,and analyzed by GC-MS.The regular pattern was used for identifying the sterols in a dinoflagellate from the Symbodinium sp.
文摘汽车悬架控制系统是一个由较多非线性因素共同作用的复杂系统,针对传统PID控制效果不理想的问题,通过数值拟合的方式引入弹簧与阻尼等非线性影响因素,建立1/4汽车悬架非线性动力学模型,借鉴免疫反馈原理,结合积分控制的规律,提出一种模糊免疫PID(proportion integral derivative)控制方法,并利用免疫进化算法进行参数优化设计。仿真结果表明,该方法在汽车非线性悬架控制系统中可行且有效,其控制器性能也优于常规的PID控制器,具有更好的响应特性,同时也提高了汽车的操作稳定性和乘坐舒适性。
文摘Our understanding of solid earth is from the surface, but the depth we can reach is very limited. So, most of the interpretations of geological processes and mechanisms extrapolated from all kinds of the surface phenomena is greatly uncertain. Recently many researchers concentrate their efforts to the geological and geophysical studying of the deep processes of the solid earth. The International Lithosphere Project (ILP) started in 1981 now is also a frontier field. One of the concentrations of this project is the 3\|D structure, tectonic evolution and the dynamic models of lithosphere\|asthenosphere system (Li Xiaobo etc., 1997). The studying of the igneous rocks and bearing deep\|seated xenoliths, as one of the effective methods probing the structure and evolution of the lithosphere, plays a very important role in these aspects (Deng Jinfu et al., 1996; Lu Fengxiang, 1997).Commonly, magmas come to the surface in great speed and the covering lithosphere should be relatively thinner. For example, the thickness of the lithosphere in East China is about 60～80km in the era when the volcanoes erupted (Deng Jinfu et al. 1994). Recently, many deep\|seated xenoliths were found in several localities of southwest Tianshan (Han Baofu et al., 1998). But in Qinghai—Xizang plateau, “So far no any xenoliths of mantle rocks as peridotites, lherzolites and harzburgites and high pressure granulites were found (Deng Wanming et al., 1997)”.. But in the fieldwork of 1998 we find some deep\|seated xenoliths in Cenozoic basaltic rocks in Kangxiwa region, West Kunlun, China. This work is a part of the project “XinJiang DuShanZi—QuanShuiGou transect” managed by academician Xiao Xuchang.
