Metalenses have gained significant attention and have been widely utilized in optical systems for focusing and imaging,owing to their lightweight,high-integration,and exceptional-flexibility capabilities.Traditional d...Metalenses have gained significant attention and have been widely utilized in optical systems for focusing and imaging,owing to their lightweight,high-integration,and exceptional-flexibility capabilities.Traditional design methods neglect the coupling effect between adjacent meta-atoms,thus harming the practical performance of meta-devices.The existing physical/data-driven optimization algorithms can solve the above problems,but bring significant time costs or require a large number of data-sets.Here,we propose a physics-data-driven method employing an“intelligent optimizer”that enables us to adaptively modify the sizes of the meta-atom according to the sizes of its surrounding ones.The implementation of such a scheme effectively mitigates the undesired impact of local lattice coupling,and the proposed network model works well on thousands of data-sets with a validation loss of 3×10^(−3).Based on the“intelligent optimizer”,a 1-cm-diameter metalens is designed within 3 hours,and the experimental results show that the 1-mm-diameter metalens has a relative focusing efficiency of 93.4%(compared to the ideal focusing efficiency)and a Strehl ratio of 0.94.Compared to previous inverse design method,our method significantly boosts designing efficiency with five orders of magnitude reduction in time.More generally,it may set a new paradigm for devising large-aperture meta-devices.展开更多
The detonation wave-aiming warhead can effectively enhance the lethality efficiency. In the past, rules for casing rupture and velocity distribution under asymmetrical initiations were not adequately investigated. In ...The detonation wave-aiming warhead can effectively enhance the lethality efficiency. In the past, rules for casing rupture and velocity distribution under asymmetrical initiations were not adequately investigated. In this study, X-ray photography and numerical modelling are used to examine the casing expansions under centre point, asymmetrical one-point, and asymmetrical two-point(with central angles of 45° and 90°) initiations. The results indicate that early casing ruptures are caused by local high pressures, induced by the initiation, detonation wave interaction, and Mach wave onset. The fragment shapes are controlled by the impact angle of the detonation wave. The fragment velocity distributions differ under different initiation types, and the end rarefaction waves can affect the velocity distribution.This study can serve as a reference for the design and optimization of high-efficiency warheads.展开更多
Fruit quality is defined by attributes that give value to a commodity.Flavor,texture,nutrition,and shelf life are key quality traits that ensure market value and consumer acceptance.In pear fruit,soluble sugars,organi...Fruit quality is defined by attributes that give value to a commodity.Flavor,texture,nutrition,and shelf life are key quality traits that ensure market value and consumer acceptance.In pear fruit,soluble sugars,organic acids,amino acids,and total flavonoids contribute to flavor and overall quality.Transcription factors(TFs)regulate the accumulation of these metabolites during development or in response to the environment.Here,we report a novel TF,PpbZIP44,as a positive regulator of primary and secondary metabolism in pear fruit.Analysis of the transient overexpression or RNAi-transformed pear fruits and stable transgenic tomato fruits under the control of the fruit-specific E8 promoter demonstrated that PpZIP44 substantially affected the contents of soluble sugar,organic acids,amino acids,and flavonoids.In E8::PpbZIP44 tomato fruit,genes involved in carbohydrate metabolism,amino acid,and flavonoids biosynthesis were significantly induced.Furthermore,in PpbZIP44 overexpression or antisense pear fruits,the expression of genes in the related pathways was significantly impacted.PpbZIP44 directly interacted with the promoter of PpSDH9 and PpProDH1 to induce their expression,thereby depleting sorbitol and proline,decreasing citrate and malate,and enhancing fructose contents.PpbZIP44 also directly bound to the PpADT and PpF3H promoters,which led to the carbon flux toward phenylalanine metabolites and enhanced phenylalanine and flavonoid contents.These findings demonstrate that PpbZIP44 mediates multimetabolism reprogramming by regulating the gene expression related to fruit quality compounds.展开更多
Stress corrosion cracking (SCC) of X70 pipeline steel in simulated solution of the acidic soil in Yingtan in China was investigated using slow strain rate test (SSRT), SEM and potentiodynamic polarization technique. E...Stress corrosion cracking (SCC) of X70 pipeline steel in simulated solution of the acidic soil in Yingtan in China was investigated using slow strain rate test (SSRT), SEM and potentiodynamic polarization technique. Experiment results indicate that X70 steel is highly susceptible to SCC as applied potential reduces, which is manifested in loss of toughness and brittle fracture. Constant polarization current can detect the occurrence of SCC. The lower the polarization current is the sooner stress corrosion cracking occurs. The SCC mechanisms are different at varying potentials. When potential is higher than open circuit potential, anodic process controls SCC, whereas when potential is far lower than open circuit potential, cathodic process controls SCC, and between these two potential regions, a combined electrochemical process controls the SCC. Stress or strain has a synergistic effect with electrochemical reactions to accelerate the cathodic hydrogen evolution process, which makes the X70 pipeline steel to be more susceptible to SCC.展开更多
Ionic liquid(IL),1-butyl-3-methylimidazolium hexafluorophosphate([BMIM]PF6)as a new and environmentally friendly diluent was introduced to prepare poly(vinylidene fluoride)(PVDF)membranes via thermally induced phase s...Ionic liquid(IL),1-butyl-3-methylimidazolium hexafluorophosphate([BMIM]PF6)as a new and environmentally friendly diluent was introduced to prepare poly(vinylidene fluoride)(PVDF)membranes via thermally induced phase separation(TIPS).Phase diagram of PVDF/[BMIM]PF6 was measured.The effects of polymer concentration and quenching temperature on the morphologies,properties,and performances of the PVDF membranes were investigated.When the polymer concentration was 15 wt%,the pure water flux of the fabricated membrane was up to nearly 2000 L·m-2·h-1,along with adequate mechanical strength.With the increasing of PVDF concentration and quenching temperature,mean pore size and water permeability of the membrane decreased.SEM results showed that PVDF membranes manufactured by ionic liquid(BMIm PF6)presented spherulite structure.And the PVDF membranes were represented asβphase by XRD and FTIR characterization.It provides a new way to prepare PVDF membranes with piezoelectric properties.展开更多
The effects of vegetation restoration on matrix structure and erosion resistance of iron tailings were studied at dump sites in Malanzhuang, Qian'an, Hebei province, China. The restoration process involved soil sp...The effects of vegetation restoration on matrix structure and erosion resistance of iron tailings were studied at dump sites in Malanzhuang, Qian'an, Hebei province, China. The restoration process involved soil spray sowing restoration model with Rhus typhina, soil and iron tailings admixture spray sowing restoration model with Amorpha fruticosa Linn. and six-hole brick restoration model with Pinus tabulaeformis Carriere.–Amorpha fruticosa Linn. mixed-forest, and direct restoration model with Hippophae rhamnoides and Sabina vulgaris. Results show that the composition and distribution of particles and aggregates were closely related to erosion resistance(P < 0.05), indicating that matrix structure of iron tailings play an important role in erosion resistance. The improvement in matrix structure of iron tailings by the different restoration models was in the order of R. typhina soil spray sowing > A. fruticosa soil and iron tailings admixture spray sowing > mixed-forest six-hole brick >H. rhamnoides direct restoration > S. vulgaris direct restoration. The R. typhina soil spray sowing restorationmodel resulted in the greatest improvement in matrix structure of iron tailings, increasing the clay(10.6%) and large particle aggregates(18.7%) contents significantly(P < 0.01). Simultaneously, particle population, grading conditions(Cu= 28.86, Cs= 1.65), and aggregate stability(6.02) were significantly improved. The A. fruticosa soil and iron tailings admixture spray sowing restoration model,which effectively improved particle distribution(Cu-= 8.51, Cs= 1.07), increased the number of large aggregates considerably(9.6%), thereby increasing aggregate stability(6.2). The six-hole brick model significantly increased the number of large aggregates(4.0%) and improved the stability of aggregates(6.2). H. rhamnoides direct restoration improved the stability of aggregates(5.1)but showed no other significant improvements. The effect of S. vulgaris direct restoration on matrix structure of iron tailings was not significant. Due to its dependence on matrix structure of iron tailings, the erosion resistance of R.typhina soil spray sowing restoration model was the greatest, while that of S. vulgaris direct restoration was the weakest. There was no significant difference in the erosion resistance of the other models. Overall, vegetation restoration supplemented by soil spray sowing restoration and engineering measures is superior to in situ direct vegetation restoration in the short-term. In-situ direct restoration has long-term ecological significance because of its advanced concept of near-natural restoration and the advantages of low cost, easy operation, and low secondary damage.展开更多
N-doped coaxial CNTs@α-Fe_2O_3@C nanofibers have been successfully synthesized according to a facile solvothermal/hydrothermal method.The obtained CNTs@α-Fe_2O_3@C nanofibers composites exhibited special three-dimen...N-doped coaxial CNTs@α-Fe_2O_3@C nanofibers have been successfully synthesized according to a facile solvothermal/hydrothermal method.The obtained CNTs@α-Fe_2O_3@C nanofibers composites exhibited special three-dimensional(3-D)network structure,which endows they promising candidate for anode materials of lithium ion battery.The coaxial property of CNTs@α-Fe_2O_3@C nanofibers could significantly improve the cycling and rate performance owing to the acceleration of charge/electron transfer,improvement of conductivity,maintaining of structural integrity and inhibiting the aggregation.Theα-Fe_2O_3nanoparticles with small size and high percentage of N-doped amount could further improve the electrochemical performance.As for the CNT@α-Fe_2O_3@C nanofibers,the capacity presented a high value of1255.4 mAh/g at 0.1 C,and retained at 1213.4 mAh/g after 60 cycles.Even at high rate of 5 C,the capacity still exhibited as high as 319 mAh/g.The results indicated that the synthesized N-doped coaxial CNTs@α-Fe_2O_3@C nanofibers exhibited high cycling and rate performance.展开更多
Integrated circuit(IC)industry has fully considered the fact that the Moore’s Law is slowing down or ending.Alternative solutions are highly and urgently desired to break the physical size limits in the More-than-Moo...Integrated circuit(IC)industry has fully considered the fact that the Moore’s Law is slowing down or ending.Alternative solutions are highly and urgently desired to break the physical size limits in the More-than-Moore era.Integrated silicon photonics technology exhibits distinguished potential to achieve faster operation speed,less power dissipation,and lower cost in IC industry,because their COMS compatibility,fast response,and high monolithic integration capability.Particularly,compared with other on-chip resonators(e.g.microrings,2D photonic crystal cavities)silicon-on-insulator(SOI)-based photonic crystal nanobeam cavity(PCNC)has emerged as a promising platform for on-chip integration,due to their attractive properties of ultra-high Q/V,ultra-compact footprints and convenient integration with silicon bus-waveguides.In this paper,we present a comprehensive review on recent progress of on-chip PCNC devices for lasing,modulation,switching/filting and label-free sensing,etc.展开更多
With epoxy coal tar as the coating material, the electrochemical corrosion behavior of Q235 with different kinds of bulk coating holidays has been investigated with EIS (Electrochemical Impedance Spectroscopy) in a 3....With epoxy coal tar as the coating material, the electrochemical corrosion behavior of Q235 with different kinds of bulk coating holidays has been investigated with EIS (Electrochemical Impedance Spectroscopy) in a 3.5vol％ NaCl aqueous solution. The area ratio of bulk coating holiday to total coating area of steel is 4.91％. The experimental results showed that at free corrosion potential, the corrosion of carbon steel with disbonded coating holiday is heavier than that with broken holiday and disbonded & broken holiday with time; Moreover, the effectiveness of Cathodic Protection (CP) of carbon steel with broken holiday is better than that with disbonded holiday and disbonded & broken holiday on CP potential-850 mV (vs CSE). Further analysis indicated that the two main reasons for corrosion are electrolyte solution slowly penetrating the coating, and crevice corrosion at steel/coating interface near holidays. The ratio of impedance amplitude (Z) of different frequency to minimum frequency is defined as K value. The change rate of K with frequency is related to the type of coating holiday.展开更多
Objective: Breast cancer is a major cancer threatening the health of women globally. To elucidate the effect ofthe circHIAT1/miR-19a-3p/phosphatase and tensin homolog (PTEN) axis on regulating the malignant phenotype ...Objective: Breast cancer is a major cancer threatening the health of women globally. To elucidate the effect ofthe circHIAT1/miR-19a-3p/phosphatase and tensin homolog (PTEN) axis on regulating the malignant phenotype ofbreast cancer cells. Methods: The mRNA expression pattern of circHIAT1, miR-19a-3p, and PTEN was checked byreal-time quantitative polymerase chain reaction. Then, the knockdown assay was carried out to explore the effect ofcircHIAT1 and miR-19a-3p on breast cancer. The relative cell experiments, including MTT assay, scratch assay,transwell invasion assay, and flow cytometry analysis, were conducted to verify the influence of circHIAT1 and miR-19a-3p on breast cancer cells. Results: The levels of PTEN and circHIAT1 were reduced, while that of miR-19a-3pwas elevated in breast cancer tissues and cells. MiR-19a-3p was proved to be the target gene of circHIAT1 via a dualluciferase experiment, which could also modulate the PTEN mRNA level. Overexpression of circHIAT1 was able toundermine the growth, migratory ability, and invasiveness in breast cancer cells, which could be antagonized by miR-19a-3p mimic. The inhibition of miR-19a-3p in vitro also impaired the malignancy of breast cancer, which dependedon the modulation of PTEN expression. Conclusion: CircHIAT1 controls the PTEN expression level in cells of breastcancer by negatively regulating miR-19a-3p. This mechanism controls the growth, invasion, and migration of breastcancer.展开更多
This study was conducted to explore the construction of scaffolding teaching mode of Traditional Chinese Medicine under the background of"Internet+".The students of Grade 2018 majoring in traditional Chinese...This study was conducted to explore the construction of scaffolding teaching mode of Traditional Chinese Medicine under the background of"Internet+".The students of Grade 2018 majoring in traditional Chinese medicine were selected as the object,and some chapters of the textbook of traditional Chinese medicine were selected and taught by the traditional teaching mode while interspersing the scaffolding teaching mode,in order to help the implementation of the scaffolding teaching model.We adopted the methods of setting up situational scaffolding,question scaffolding and guide scaffolding to carry out relevant teaching contents.The scaffolding instruction model has a good degree of participation,and to a certain extent,it stimulates students'self-consciousness and enthusiasm,and improves their ability of analyzing and solving problems and their spirit of innovation.展开更多
The reservoir thickness of sub-member of Lower Permain in the south of the eastern margin of Ordos Basin is thin and large variable i laterally. And the seismic response characteristics of sandstone reservoir are doub...The reservoir thickness of sub-member of Lower Permain in the south of the eastern margin of Ordos Basin is thin and large variable i laterally. And the seismic response characteristics of sandstone reservoir are doubly interfered by the strong reflection sidelobes of overlying 5# coal seam and underlying 8# coal seam. In view of this situation, in order to better eliminate the influence of upper and lower coal seams and improve the accuracy of reservoir prediction, the strategy of de-strong seismic reflection and de-logging (curve) interference is adopted to carry out the matching of logging and seismic, and on this basis, uses the seismic waveform indication inversion to predict the thin sandstone. The steps are as follows: firstly, by using wavelet decomposition and reconstruction technology, select the seismic wavelet component that can better characterize the reservoir or oil & gas to reasonablely reconstruct seismic data, weaken the influence of the strong reflection from overlying 5# coal seam and underlying 8# coal seam, and highlight the response of weak seismic reflection of tight sandstone in Shan 2<sup>3</sup> sub-member;Then, the acoustic value of coal seam is corrected to that of mudstone on the logging curve to maintain the consistency of logseismic data. This method realizes the effective identification of sandstone reservoir in Shan 2<sup>3</sup> sub-member, and greatly improves the target-penetrated rate and sandstone-penetrated rate of horizontal wells.展开更多
BACKGROUND:Previous studies have demonstrated that homocysteine is an independent risk factor for ischemic stroke,as determined by detection of apoptosis and oxygen-free radical scavengers following cerebral ischemia....BACKGROUND:Previous studies have demonstrated that homocysteine is an independent risk factor for ischemic stroke,as determined by detection of apoptosis and oxygen-free radical scavengers following cerebral ischemia.However,the mechanisms of homocysteine remain unclear.Several reports have addressed the effects of homocysteine on ischemic stroke.OBJECTIVE:To analyze the effects of homocysteine on apoptosis,intracellular superoxide dismutase(SOD) activity,and malondialdehyde content in tissue surrounding hematoma in rats with cerebral hemorrhage,and to determine the action pathway of malondialdehyde following cerebral hemorrhage.DESIGN,TIME AND SETTING:The randomized,controlled,animal experiment was performed at the Laboratory of Molecular Biology,Hospital Affiliated to Luzhou Medical College,China from April 2007 to April 2008.MATERIALS:In situ apoptosis detection kit(Roche,Mannheim,Germany),SOD detection kit and malondialdehyde detection kit(Nanjing Jiancheng Bioengineering Institute,China),and homocysteine(Sigma,St Louis,MO,USA) were used in the present study.METHODS:A total of 75 Sprague Dawley rats were equally and randomly assigned to sham surgery,model,and homocysteine groups.Autologous blood was infused into the caudate putamen of rats to establish models of cerebral hemorrhage in model and homocysteine groups.Homocysteine was injected directly into the brain through the skull at the hematoma hemisphere at 30 minutes after model induction in the homocysteine group.MAIN OUTCOME MEASURES:At 6,12,24,and 72 hours,as well as 1 week,post-surgery,neurological deficits were observed in each group.Brain water content was measured using the dry-wet weight method.Cell apoptosis in tissue surrounding the hematoma was detected utilizing terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling(TUNEL).SOD activity and malondialdehyde content in tissue surrounding the hematoma were respectively measured using the xanthine oxidase and thiobarbituric acid methods.RESULTS:Neurological function was similar between model and homocysteine groups following cerebral hemorrhage(P > 0.05).Brain water content was increased at 12 hours post-surgery,peaked at 3 days,and remained unchanged at 7 days in the model group.Brain edema was not significantly aggravated following homocysteine intervention(P > 0.05),but SOD activity significantly decreased and malondialdehyde content significantly increased(P < 0.05).The number of apoptotic cells increased in rats with cerebral hemorrhage at 12 hours(P < 0.05),and numbers peaked at 72 hours following model establishment(P < 0.05).The time of peak value was identical between model and homocysteine groups.Brain water content was negatively associated with SOD activity(rmodel group =-0.448,P < 0.05;rhomocysteine group =-0.612,P < 0.05),but was positively associated with malondialdehyde content(rmodel group = 0.542,P < 0.05;rhomocysteine group = 0.684,P < 0.05) in brain tissues surrounding the hematoma following surgery in model and homocysteine groups.CONCLUSION:Homocysteine aggravates neurological dysfunction and brain edema in rats with cerebral hemorrhage.The mechanisms of action are likely associated with production of oxygen-free radical and cellular apoptosis following cerebral hemorrhage.展开更多
Accelerated corrosion test of stainless steel with weld was carried out to investigate the corrosion behavior under the wet-dry cyclic condition in the atmosphere containing Cl?. In the surface morphology, corrosion p...Accelerated corrosion test of stainless steel with weld was carried out to investigate the corrosion behavior under the wet-dry cyclic condition in the atmosphere containing Cl?. In the surface morphology, corrosion products were analyzed by metal- lographic observation, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the damage to stainless steel with weld in the atmosphere containing Cl? is due to localized corrosion, especially pitting and galvanic corrosion. Weld acts as the anode, whereas matrix acts as the cathode in the corrosion process. The pitting corrosion, including the nucleation and growth of a stable pit, is promoted by the presence of wet-dry cycles, especially during the drying stage. Pits centralizing in weld are found to be grouped together like colonies, with a number of smaller pits surrounding a larger pit. The composition of the corro- sion products is Fe2O3, Cr2O3, Fe3O4, NiCrO4, etc.展开更多
This study aims at providing systematically insights to clarify the impact of cathodic polarization on the stress corrosion cracking(SCC)behavior of 21 Cr2 NiMo steel.Slow-strain-rate tensile tests demonstrated that 2...This study aims at providing systematically insights to clarify the impact of cathodic polarization on the stress corrosion cracking(SCC)behavior of 21 Cr2 NiMo steel.Slow-strain-rate tensile tests demonstrated that 21 Cr2 NiMo steel is highly sensitive to hydrogen embrittlement at strong cathodic polarization.The lowest SCC susceptibility occurred at-775 mV vs.SCE,whereas the SCC susceptibility was remarkably higher at potentials below-950 mV vs.SCE.Scanning electron microscopy(SEM)and electron backscattered diffraction(EBSD)revealed that the cathodic potential decline caused a transition from transgranular to intergranular mode in the fracture path.The intergranular mode transformed from bainite boundaries separation to prior austenitic grain boundaries separation under stronger cathodic polarization.Furthermore,corrosion pits promoted the nucleation of SCC cracks.In conclusion,with the decrease in the applied potential,the SCC mechanism transformed from the combination of hydrogen embrittlement and anodic dissolution to typical hydrogen embrittlement.展开更多
Machine-learning and big data are among the latest approaches in corrosion research.The biggest challenge in corrosion research is to accurately predict how materials will degrade in a given environment.Corrosion big ...Machine-learning and big data are among the latest approaches in corrosion research.The biggest challenge in corrosion research is to accurately predict how materials will degrade in a given environment.Corrosion big data is the application of mathematical methods to huge amounts of data to find correlations and infer probabilities.It is possible to use corrosion big data method to distinguish the influence of the minimal changes of alloying elements and small differences in microstructure on corrosion resistance of low alloy steels.In this research,corrosion big data evaluation methods and machine learning were used to study the effect of Sb and Sn,as well as environmental factors on the corrosion behavior of low alloy steels.Results depict corrosion big data method can accurately identify the influence of various factors on corrosion resistance of low alloy and is an effective and promising way in corrosion research.展开更多
Cyhalodiamide is a novel agrochemical which is effective against Lepidoptera pests,including Cnaphalocrocis medinalis,Chilo suppressalis,Pieris rapae,Plutella xylostella,Helicoverpa armigera,etc.In the study,a fast an...Cyhalodiamide is a novel agrochemical which is effective against Lepidoptera pests,including Cnaphalocrocis medinalis,Chilo suppressalis,Pieris rapae,Plutella xylostella,Helicoverpa armigera,etc.In the study,a fast and accurate analytical method was developed to detect cyhalodiamide in Chinese typical rice field environment by a modified Qu ECh ERS(Quick,Easy,Cheap,Effective,Rugged,Safe)method with UPLC-MS/MS(ultra-high performance chromatography-tandem mass spectrometry).The mean recoveries of cyhalodiamide varied from 73.5% to 107.5%,with the RSDs from 1.2% to 10.7%.The limits of determination(LODs)were 0.0005 mg·kg^(-1),and the limits of quantitation(LOQs)were from 0.002 to 0.01 mg·kg^(-1)in all five matrices.This method was used to determine cyhalodiamide residues for studies of the distribution and degradation kinetics in rice field environment.The field trials results showed that cyhalodiamide was easily degradable and the half-lives were4.2–13.6 d in rice straw,8.77 d in paddy soil and 5.37–8.45 d in paddy water,respectively.The final residues of cyhalodiamide in brown rice were below 0.35 mg·kg^(-1).The used dosage of 33.75 g·hm^(-2)with pre-harvest interval(PHI)of 21 d and the maximum residue limit(MRL)of cyhalodiamide in rice at 0.1 mg·kg^(-1)were recommended,which would be safe to human health and environment.The developed analytical method will be useful to monitor cyhalodiamide residues and safety evaluation in rice environment.展开更多
BACKGROUND:Gene therapy for Parkinson's disease is being explored as an effective strategy to restore and protect the function of neuronal cells in the substantia nigra.Regulation of gene expression is necessary f...BACKGROUND:Gene therapy for Parkinson's disease is being explored as an effective strategy to restore and protect the function of neuronal cells in the substantia nigra.Regulation of gene expression is necessary for gene therapy to avoid adverse effects due to excessive synthesis of transgene products.OBJECTIVE:Here we developed recombinant adeno-associated virus(AAV) as a viral vector-mediated gene regulation system based on Cre recombinase fused to the mutated ligand-binding domain of the estrogen receptor(CreERT2) + inducing agent tamoxifen.Inducible Cre recombinase was used to reduce tyrosine hydroxylase gene expression and to prevent the excessive increase in dopamine.DESIGN,TIME AND SETTING:A genetic engineering in vitro comparative study and randomized controlled animal experiment.This study was conducted at the Gene Therapy Center,Jichi Medical School,Japan from June 2002 to June 2004.METHODS:To construct a recombinant AAV vector carrying a dopamine synthase gene.The tyrosine hydroxylase gene was inserted using a loxP fragment that could be regulated by Cre recombinase.The recombinant AAV vector carrying the CreERT2 gene was co-transduced with HEK293 cells and the corpus striatum in a rat model of Parkinson's disease,with inducing agent tamoxifen to regulate gene expression.MAIN OUTCOME MEASURES:The levels of dopamine and aromatic L-amino acid decarboxylase(AADC) activity were detected in HEK293 cell medium and in the corpus striatum in a rat model of Parkinson's disease using high-performance liquid chromatography.Immunofluorescence double staining was used to observe tyrosine hydroxylase and Cre or AADC co-expression in HEK293 cell medium.Immunohistochemical staining was employed to observe tyrosine hydroxylase and AADC expression and behavioral changes were measured in Parkinson's rats.RESULTS:Transfected AAV-CreERT2 and AAV expressing dopamine synthesis enzymes could increase the synthesis of dopamine in HEK293 medium and Parkinson's rat striatum(P < 0.01) and improve the rotational behavior of Parkinson's rats.While tamoxifen markedly reduced overproduction of dopamine caused by cotransfection of viral vectors(P < 0.01),but did not affect the expression and activity of AADC.CONCLUSION:The application of AAV vector-encoded tyrosine hydroxylase gene under the gene regulation system of Cre-ERT2,after tamoxifen treatment,can effectively control the generation of genetically modified products to reduce the production of excessive dopamine in vivo and in vitro.Therefore,this method can increase the safety of gene therapy.展开更多
基金supported by the National Key Research and Development Program (2021YFA1401000)the National Natural Science Foundation of China (No.61975210,62175242 and 62305345)Sichuan Science and Technology Program (2020YFJ0001).
文摘Metalenses have gained significant attention and have been widely utilized in optical systems for focusing and imaging,owing to their lightweight,high-integration,and exceptional-flexibility capabilities.Traditional design methods neglect the coupling effect between adjacent meta-atoms,thus harming the practical performance of meta-devices.The existing physical/data-driven optimization algorithms can solve the above problems,but bring significant time costs or require a large number of data-sets.Here,we propose a physics-data-driven method employing an“intelligent optimizer”that enables us to adaptively modify the sizes of the meta-atom according to the sizes of its surrounding ones.The implementation of such a scheme effectively mitigates the undesired impact of local lattice coupling,and the proposed network model works well on thousands of data-sets with a validation loss of 3×10^(−3).Based on the“intelligent optimizer”,a 1-cm-diameter metalens is designed within 3 hours,and the experimental results show that the 1-mm-diameter metalens has a relative focusing efficiency of 93.4%(compared to the ideal focusing efficiency)and a Strehl ratio of 0.94.Compared to previous inverse design method,our method significantly boosts designing efficiency with five orders of magnitude reduction in time.More generally,it may set a new paradigm for devising large-aperture meta-devices.
基金funded by the National Natural Science Foundation of China [Grant No. 12002178]opening project of the State Key Laboratory of Explosion Science and Technology (Beijing Institute of Technology) [Grant No. KFJJ22-17M]the Fundamental Research Funds for Central Universities
文摘The detonation wave-aiming warhead can effectively enhance the lethality efficiency. In the past, rules for casing rupture and velocity distribution under asymmetrical initiations were not adequately investigated. In this study, X-ray photography and numerical modelling are used to examine the casing expansions under centre point, asymmetrical one-point, and asymmetrical two-point(with central angles of 45° and 90°) initiations. The results indicate that early casing ruptures are caused by local high pressures, induced by the initiation, detonation wave interaction, and Mach wave onset. The fragment shapes are controlled by the impact angle of the detonation wave. The fragment velocity distributions differ under different initiation types, and the end rarefaction waves can affect the velocity distribution.This study can serve as a reference for the design and optimization of high-efficiency warheads.
基金This work was supported by Jiangsu Agricultural Science and Technology Independent Innovation Fund[Grant No.CX(22)3010]the General Program of National Natural Science Foundation of China(Grant No.31872078,32272669)+2 种基金Jiangsu Modern Agricultural Industry Technology System(Grant No.JATS[2022]437,JATS[2022]438)Jiangsu Agricultural Key New Varieties Innovation(Grant No.PZCZ201726)Jiangsu Province Seed Industry Revitalization Unveiled Project:Breeding of New Pear Cultivars with High-quality and Extreme Early Ripening(Grant No.JBGS[2021]084)。
文摘Fruit quality is defined by attributes that give value to a commodity.Flavor,texture,nutrition,and shelf life are key quality traits that ensure market value and consumer acceptance.In pear fruit,soluble sugars,organic acids,amino acids,and total flavonoids contribute to flavor and overall quality.Transcription factors(TFs)regulate the accumulation of these metabolites during development or in response to the environment.Here,we report a novel TF,PpbZIP44,as a positive regulator of primary and secondary metabolism in pear fruit.Analysis of the transient overexpression or RNAi-transformed pear fruits and stable transgenic tomato fruits under the control of the fruit-specific E8 promoter demonstrated that PpZIP44 substantially affected the contents of soluble sugar,organic acids,amino acids,and flavonoids.In E8::PpbZIP44 tomato fruit,genes involved in carbohydrate metabolism,amino acid,and flavonoids biosynthesis were significantly induced.Furthermore,in PpbZIP44 overexpression or antisense pear fruits,the expression of genes in the related pathways was significantly impacted.PpbZIP44 directly interacted with the promoter of PpSDH9 and PpProDH1 to induce their expression,thereby depleting sorbitol and proline,decreasing citrate and malate,and enhancing fructose contents.PpbZIP44 also directly bound to the PpADT and PpF3H promoters,which led to the carbon flux toward phenylalanine metabolites and enhanced phenylalanine and flavonoid contents.These findings demonstrate that PpbZIP44 mediates multimetabolism reprogramming by regulating the gene expression related to fruit quality compounds.
基金supported by Chinese National Science and Technology Infrastructure Platforms Construction Project (No.2005DKA10400)Major Foundation in the Tenth Five-Year Development Plan of China (No.50499333-08)
文摘Stress corrosion cracking (SCC) of X70 pipeline steel in simulated solution of the acidic soil in Yingtan in China was investigated using slow strain rate test (SSRT), SEM and potentiodynamic polarization technique. Experiment results indicate that X70 steel is highly susceptible to SCC as applied potential reduces, which is manifested in loss of toughness and brittle fracture. Constant polarization current can detect the occurrence of SCC. The lower the polarization current is the sooner stress corrosion cracking occurs. The SCC mechanisms are different at varying potentials. When potential is higher than open circuit potential, anodic process controls SCC, whereas when potential is far lower than open circuit potential, cathodic process controls SCC, and between these two potential regions, a combined electrochemical process controls the SCC. Stress or strain has a synergistic effect with electrochemical reactions to accelerate the cathodic hydrogen evolution process, which makes the X70 pipeline steel to be more susceptible to SCC.
基金the financial support of the National Natural Science Foundation of China(Grant No.21606125)the Natural Science Foundation of Jiangsu Province(Grant No.BK20160984)+3 种基金the National Key R&D Program of China(Grant No.2017YFC0403702)the Materials-Oriented Chemical Engineering State Key Laboratory Program(KL16-09)the open project program of Jiangsu Key Lab for Chemistry of Low-Dimensional Materials(JSKC17005)the Priority Academic Program Development of Jiangsu Higher Education Institution(PAPD)。
文摘Ionic liquid(IL),1-butyl-3-methylimidazolium hexafluorophosphate([BMIM]PF6)as a new and environmentally friendly diluent was introduced to prepare poly(vinylidene fluoride)(PVDF)membranes via thermally induced phase separation(TIPS).Phase diagram of PVDF/[BMIM]PF6 was measured.The effects of polymer concentration and quenching temperature on the morphologies,properties,and performances of the PVDF membranes were investigated.When the polymer concentration was 15 wt%,the pure water flux of the fabricated membrane was up to nearly 2000 L·m-2·h-1,along with adequate mechanical strength.With the increasing of PVDF concentration and quenching temperature,mean pore size and water permeability of the membrane decreased.SEM results showed that PVDF membranes manufactured by ionic liquid(BMIm PF6)presented spherulite structure.And the PVDF membranes were represented asβphase by XRD and FTIR characterization.It provides a new way to prepare PVDF membranes with piezoelectric properties.
基金financed by the National Science and Technology Program in Rural Areas in 12th Five-Year(No.2012AA101403-32012)the High Level Talents Program in Hebei Province(B2014010004)the Provincial Financial Forestry Science and Technology Popularization Program in Hebei Province(201705201)。
文摘The effects of vegetation restoration on matrix structure and erosion resistance of iron tailings were studied at dump sites in Malanzhuang, Qian'an, Hebei province, China. The restoration process involved soil spray sowing restoration model with Rhus typhina, soil and iron tailings admixture spray sowing restoration model with Amorpha fruticosa Linn. and six-hole brick restoration model with Pinus tabulaeformis Carriere.–Amorpha fruticosa Linn. mixed-forest, and direct restoration model with Hippophae rhamnoides and Sabina vulgaris. Results show that the composition and distribution of particles and aggregates were closely related to erosion resistance(P < 0.05), indicating that matrix structure of iron tailings play an important role in erosion resistance. The improvement in matrix structure of iron tailings by the different restoration models was in the order of R. typhina soil spray sowing > A. fruticosa soil and iron tailings admixture spray sowing > mixed-forest six-hole brick >H. rhamnoides direct restoration > S. vulgaris direct restoration. The R. typhina soil spray sowing restorationmodel resulted in the greatest improvement in matrix structure of iron tailings, increasing the clay(10.6%) and large particle aggregates(18.7%) contents significantly(P < 0.01). Simultaneously, particle population, grading conditions(Cu= 28.86, Cs= 1.65), and aggregate stability(6.02) were significantly improved. The A. fruticosa soil and iron tailings admixture spray sowing restoration model,which effectively improved particle distribution(Cu-= 8.51, Cs= 1.07), increased the number of large aggregates considerably(9.6%), thereby increasing aggregate stability(6.2). The six-hole brick model significantly increased the number of large aggregates(4.0%) and improved the stability of aggregates(6.2). H. rhamnoides direct restoration improved the stability of aggregates(5.1)but showed no other significant improvements. The effect of S. vulgaris direct restoration on matrix structure of iron tailings was not significant. Due to its dependence on matrix structure of iron tailings, the erosion resistance of R.typhina soil spray sowing restoration model was the greatest, while that of S. vulgaris direct restoration was the weakest. There was no significant difference in the erosion resistance of the other models. Overall, vegetation restoration supplemented by soil spray sowing restoration and engineering measures is superior to in situ direct vegetation restoration in the short-term. In-situ direct restoration has long-term ecological significance because of its advanced concept of near-natural restoration and the advantages of low cost, easy operation, and low secondary damage.
基金the National Natural Science Foundation of China (No. 91634108, 21376148 and 61503246)National Key Program(2017FYA0205300)
文摘N-doped coaxial CNTs@α-Fe_2O_3@C nanofibers have been successfully synthesized according to a facile solvothermal/hydrothermal method.The obtained CNTs@α-Fe_2O_3@C nanofibers composites exhibited special three-dimensional(3-D)network structure,which endows they promising candidate for anode materials of lithium ion battery.The coaxial property of CNTs@α-Fe_2O_3@C nanofibers could significantly improve the cycling and rate performance owing to the acceleration of charge/electron transfer,improvement of conductivity,maintaining of structural integrity and inhibiting the aggregation.Theα-Fe_2O_3nanoparticles with small size and high percentage of N-doped amount could further improve the electrochemical performance.As for the CNT@α-Fe_2O_3@C nanofibers,the capacity presented a high value of1255.4 mAh/g at 0.1 C,and retained at 1213.4 mAh/g after 60 cycles.Even at high rate of 5 C,the capacity still exhibited as high as 319 mAh/g.The results indicated that the synthesized N-doped coaxial CNTs@α-Fe_2O_3@C nanofibers exhibited high cycling and rate performance.
基金This work was supported by the National Key R&D Program of China(Grant No.2016YFA0301302 and No.2018YFB 2200401)the National Natural Science Foundation of China(Grant Nos.11974058,11825402,11654003,61435001)+4 种基金Beijing Academy of Quantum Information Sciences(Grant No.Y18G20)Key R&D Program of Guangdong Province(Grant No.2018B030329001)Beijing Nova Program(Grant No.Z201100006820125)from Beijing Municipal ScienceTechnology Commission,Fundamental Research Funds for the Central Universities(Grant No.2018XKJC05)the High Performance Computing Platform of Peking University.
文摘Integrated circuit(IC)industry has fully considered the fact that the Moore’s Law is slowing down or ending.Alternative solutions are highly and urgently desired to break the physical size limits in the More-than-Moore era.Integrated silicon photonics technology exhibits distinguished potential to achieve faster operation speed,less power dissipation,and lower cost in IC industry,because their COMS compatibility,fast response,and high monolithic integration capability.Particularly,compared with other on-chip resonators(e.g.microrings,2D photonic crystal cavities)silicon-on-insulator(SOI)-based photonic crystal nanobeam cavity(PCNC)has emerged as a promising platform for on-chip integration,due to their attractive properties of ultra-high Q/V,ultra-compact footprints and convenient integration with silicon bus-waveguides.In this paper,we present a comprehensive review on recent progress of on-chip PCNC devices for lasing,modulation,switching/filting and label-free sensing,etc.
基金financially supported by the National Nature Science foundation of China (No.50301003 and 50461004)
文摘With epoxy coal tar as the coating material, the electrochemical corrosion behavior of Q235 with different kinds of bulk coating holidays has been investigated with EIS (Electrochemical Impedance Spectroscopy) in a 3.5vol％ NaCl aqueous solution. The area ratio of bulk coating holiday to total coating area of steel is 4.91％. The experimental results showed that at free corrosion potential, the corrosion of carbon steel with disbonded coating holiday is heavier than that with broken holiday and disbonded & broken holiday with time; Moreover, the effectiveness of Cathodic Protection (CP) of carbon steel with broken holiday is better than that with disbonded holiday and disbonded & broken holiday on CP potential-850 mV (vs CSE). Further analysis indicated that the two main reasons for corrosion are electrolyte solution slowly penetrating the coating, and crevice corrosion at steel/coating interface near holidays. The ratio of impedance amplitude (Z) of different frequency to minimum frequency is defined as K value. The change rate of K with frequency is related to the type of coating holiday.
基金All experimental procedures were conducted in accordance with Animal Ethics Procedures and Guidelines of the Animal Center,Yunnan University Animal Ethics Committee(Ethics Review Number:YNU20220296).
文摘Objective: Breast cancer is a major cancer threatening the health of women globally. To elucidate the effect ofthe circHIAT1/miR-19a-3p/phosphatase and tensin homolog (PTEN) axis on regulating the malignant phenotype ofbreast cancer cells. Methods: The mRNA expression pattern of circHIAT1, miR-19a-3p, and PTEN was checked byreal-time quantitative polymerase chain reaction. Then, the knockdown assay was carried out to explore the effect ofcircHIAT1 and miR-19a-3p on breast cancer. The relative cell experiments, including MTT assay, scratch assay,transwell invasion assay, and flow cytometry analysis, were conducted to verify the influence of circHIAT1 and miR-19a-3p on breast cancer cells. Results: The levels of PTEN and circHIAT1 were reduced, while that of miR-19a-3pwas elevated in breast cancer tissues and cells. MiR-19a-3p was proved to be the target gene of circHIAT1 via a dualluciferase experiment, which could also modulate the PTEN mRNA level. Overexpression of circHIAT1 was able toundermine the growth, migratory ability, and invasiveness in breast cancer cells, which could be antagonized by miR-19a-3p mimic. The inhibition of miR-19a-3p in vitro also impaired the malignancy of breast cancer, which dependedon the modulation of PTEN expression. Conclusion: CircHIAT1 controls the PTEN expression level in cells of breastcancer by negatively regulating miR-19a-3p. This mechanism controls the growth, invasion, and migration of breastcancer.
基金Supported by 2017 Teaching Quality and Teaching Reform Project of Guizhou University of Traditional Chinese Medicine(3045-045170035)2018 School-level Undergraduate Teaching Engineering Construction Project of Guiyang College of Traditional Chinese Medicine(GZY-JG(2018)03)。
文摘This study was conducted to explore the construction of scaffolding teaching mode of Traditional Chinese Medicine under the background of"Internet+".The students of Grade 2018 majoring in traditional Chinese medicine were selected as the object,and some chapters of the textbook of traditional Chinese medicine were selected and taught by the traditional teaching mode while interspersing the scaffolding teaching mode,in order to help the implementation of the scaffolding teaching model.We adopted the methods of setting up situational scaffolding,question scaffolding and guide scaffolding to carry out relevant teaching contents.The scaffolding instruction model has a good degree of participation,and to a certain extent,it stimulates students'self-consciousness and enthusiasm,and improves their ability of analyzing and solving problems and their spirit of innovation.
文摘The reservoir thickness of sub-member of Lower Permain in the south of the eastern margin of Ordos Basin is thin and large variable i laterally. And the seismic response characteristics of sandstone reservoir are doubly interfered by the strong reflection sidelobes of overlying 5# coal seam and underlying 8# coal seam. In view of this situation, in order to better eliminate the influence of upper and lower coal seams and improve the accuracy of reservoir prediction, the strategy of de-strong seismic reflection and de-logging (curve) interference is adopted to carry out the matching of logging and seismic, and on this basis, uses the seismic waveform indication inversion to predict the thin sandstone. The steps are as follows: firstly, by using wavelet decomposition and reconstruction technology, select the seismic wavelet component that can better characterize the reservoir or oil & gas to reasonablely reconstruct seismic data, weaken the influence of the strong reflection from overlying 5# coal seam and underlying 8# coal seam, and highlight the response of weak seismic reflection of tight sandstone in Shan 2<sup>3</sup> sub-member;Then, the acoustic value of coal seam is corrected to that of mudstone on the logging curve to maintain the consistency of logseismic data. This method realizes the effective identification of sandstone reservoir in Shan 2<sup>3</sup> sub-member, and greatly improves the target-penetrated rate and sandstone-penetrated rate of horizontal wells.
文摘BACKGROUND:Previous studies have demonstrated that homocysteine is an independent risk factor for ischemic stroke,as determined by detection of apoptosis and oxygen-free radical scavengers following cerebral ischemia.However,the mechanisms of homocysteine remain unclear.Several reports have addressed the effects of homocysteine on ischemic stroke.OBJECTIVE:To analyze the effects of homocysteine on apoptosis,intracellular superoxide dismutase(SOD) activity,and malondialdehyde content in tissue surrounding hematoma in rats with cerebral hemorrhage,and to determine the action pathway of malondialdehyde following cerebral hemorrhage.DESIGN,TIME AND SETTING:The randomized,controlled,animal experiment was performed at the Laboratory of Molecular Biology,Hospital Affiliated to Luzhou Medical College,China from April 2007 to April 2008.MATERIALS:In situ apoptosis detection kit(Roche,Mannheim,Germany),SOD detection kit and malondialdehyde detection kit(Nanjing Jiancheng Bioengineering Institute,China),and homocysteine(Sigma,St Louis,MO,USA) were used in the present study.METHODS:A total of 75 Sprague Dawley rats were equally and randomly assigned to sham surgery,model,and homocysteine groups.Autologous blood was infused into the caudate putamen of rats to establish models of cerebral hemorrhage in model and homocysteine groups.Homocysteine was injected directly into the brain through the skull at the hematoma hemisphere at 30 minutes after model induction in the homocysteine group.MAIN OUTCOME MEASURES:At 6,12,24,and 72 hours,as well as 1 week,post-surgery,neurological deficits were observed in each group.Brain water content was measured using the dry-wet weight method.Cell apoptosis in tissue surrounding the hematoma was detected utilizing terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling(TUNEL).SOD activity and malondialdehyde content in tissue surrounding the hematoma were respectively measured using the xanthine oxidase and thiobarbituric acid methods.RESULTS:Neurological function was similar between model and homocysteine groups following cerebral hemorrhage(P > 0.05).Brain water content was increased at 12 hours post-surgery,peaked at 3 days,and remained unchanged at 7 days in the model group.Brain edema was not significantly aggravated following homocysteine intervention(P > 0.05),but SOD activity significantly decreased and malondialdehyde content significantly increased(P < 0.05).The number of apoptotic cells increased in rats with cerebral hemorrhage at 12 hours(P < 0.05),and numbers peaked at 72 hours following model establishment(P < 0.05).The time of peak value was identical between model and homocysteine groups.Brain water content was negatively associated with SOD activity(rmodel group =-0.448,P < 0.05;rhomocysteine group =-0.612,P < 0.05),but was positively associated with malondialdehyde content(rmodel group = 0.542,P < 0.05;rhomocysteine group = 0.684,P < 0.05) in brain tissues surrounding the hematoma following surgery in model and homocysteine groups.CONCLUSION:Homocysteine aggravates neurological dysfunction and brain edema in rats with cerebral hemorrhage.The mechanisms of action are likely associated with production of oxygen-free radical and cellular apoptosis following cerebral hemorrhage.
基金This work was financially supported by the National Natural Science Foundation of China (No.50601012).
文摘Accelerated corrosion test of stainless steel with weld was carried out to investigate the corrosion behavior under the wet-dry cyclic condition in the atmosphere containing Cl?. In the surface morphology, corrosion products were analyzed by metal- lographic observation, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the damage to stainless steel with weld in the atmosphere containing Cl? is due to localized corrosion, especially pitting and galvanic corrosion. Weld acts as the anode, whereas matrix acts as the cathode in the corrosion process. The pitting corrosion, including the nucleation and growth of a stable pit, is promoted by the presence of wet-dry cycles, especially during the drying stage. Pits centralizing in weld are found to be grouped together like colonies, with a number of smaller pits surrounding a larger pit. The composition of the corro- sion products is Fe2O3, Cr2O3, Fe3O4, NiCrO4, etc.
基金financially supported by the National Science and Technology Major Project,China(No.2017-Ⅶ0012-0109)。
文摘This study aims at providing systematically insights to clarify the impact of cathodic polarization on the stress corrosion cracking(SCC)behavior of 21 Cr2 NiMo steel.Slow-strain-rate tensile tests demonstrated that 21 Cr2 NiMo steel is highly sensitive to hydrogen embrittlement at strong cathodic polarization.The lowest SCC susceptibility occurred at-775 mV vs.SCE,whereas the SCC susceptibility was remarkably higher at potentials below-950 mV vs.SCE.Scanning electron microscopy(SEM)and electron backscattered diffraction(EBSD)revealed that the cathodic potential decline caused a transition from transgranular to intergranular mode in the fracture path.The intergranular mode transformed from bainite boundaries separation to prior austenitic grain boundaries separation under stronger cathodic polarization.Furthermore,corrosion pits promoted the nucleation of SCC cracks.In conclusion,with the decrease in the applied potential,the SCC mechanism transformed from the combination of hydrogen embrittlement and anodic dissolution to typical hydrogen embrittlement.
基金financially supported by the Postdoctor Research Foundation of Shunde Graduate School of University of Science and Technology Beijing(No.2022 B H003)。
文摘Machine-learning and big data are among the latest approaches in corrosion research.The biggest challenge in corrosion research is to accurately predict how materials will degrade in a given environment.Corrosion big data is the application of mathematical methods to huge amounts of data to find correlations and infer probabilities.It is possible to use corrosion big data method to distinguish the influence of the minimal changes of alloying elements and small differences in microstructure on corrosion resistance of low alloy steels.In this research,corrosion big data evaluation methods and machine learning were used to study the effect of Sb and Sn,as well as environmental factors on the corrosion behavior of low alloy steels.Results depict corrosion big data method can accurately identify the influence of various factors on corrosion resistance of low alloy and is an effective and promising way in corrosion research.
基金Supported by the National Key Research and Development Plan(2016YFD020120)the Natural Science Foundation of Hunan Province(2017JJ3165)
文摘Cyhalodiamide is a novel agrochemical which is effective against Lepidoptera pests,including Cnaphalocrocis medinalis,Chilo suppressalis,Pieris rapae,Plutella xylostella,Helicoverpa armigera,etc.In the study,a fast and accurate analytical method was developed to detect cyhalodiamide in Chinese typical rice field environment by a modified Qu ECh ERS(Quick,Easy,Cheap,Effective,Rugged,Safe)method with UPLC-MS/MS(ultra-high performance chromatography-tandem mass spectrometry).The mean recoveries of cyhalodiamide varied from 73.5% to 107.5%,with the RSDs from 1.2% to 10.7%.The limits of determination(LODs)were 0.0005 mg·kg^(-1),and the limits of quantitation(LOQs)were from 0.002 to 0.01 mg·kg^(-1)in all five matrices.This method was used to determine cyhalodiamide residues for studies of the distribution and degradation kinetics in rice field environment.The field trials results showed that cyhalodiamide was easily degradable and the half-lives were4.2–13.6 d in rice straw,8.77 d in paddy soil and 5.37–8.45 d in paddy water,respectively.The final residues of cyhalodiamide in brown rice were below 0.35 mg·kg^(-1).The used dosage of 33.75 g·hm^(-2)with pre-harvest interval(PHI)of 21 d and the maximum residue limit(MRL)of cyhalodiamide in rice at 0.1 mg·kg^(-1)were recommended,which would be safe to human health and environment.The developed analytical method will be useful to monitor cyhalodiamide residues and safety evaluation in rice environment.
基金Supported by Grants from Ministry of Education,Sci-ence,Sports and Culture,the Japanese Government,and from the Japan Ministry of Health,Labour and WelfareFunds from the Cell Science Research Foundation
文摘BACKGROUND:Gene therapy for Parkinson's disease is being explored as an effective strategy to restore and protect the function of neuronal cells in the substantia nigra.Regulation of gene expression is necessary for gene therapy to avoid adverse effects due to excessive synthesis of transgene products.OBJECTIVE:Here we developed recombinant adeno-associated virus(AAV) as a viral vector-mediated gene regulation system based on Cre recombinase fused to the mutated ligand-binding domain of the estrogen receptor(CreERT2) + inducing agent tamoxifen.Inducible Cre recombinase was used to reduce tyrosine hydroxylase gene expression and to prevent the excessive increase in dopamine.DESIGN,TIME AND SETTING:A genetic engineering in vitro comparative study and randomized controlled animal experiment.This study was conducted at the Gene Therapy Center,Jichi Medical School,Japan from June 2002 to June 2004.METHODS:To construct a recombinant AAV vector carrying a dopamine synthase gene.The tyrosine hydroxylase gene was inserted using a loxP fragment that could be regulated by Cre recombinase.The recombinant AAV vector carrying the CreERT2 gene was co-transduced with HEK293 cells and the corpus striatum in a rat model of Parkinson's disease,with inducing agent tamoxifen to regulate gene expression.MAIN OUTCOME MEASURES:The levels of dopamine and aromatic L-amino acid decarboxylase(AADC) activity were detected in HEK293 cell medium and in the corpus striatum in a rat model of Parkinson's disease using high-performance liquid chromatography.Immunofluorescence double staining was used to observe tyrosine hydroxylase and Cre or AADC co-expression in HEK293 cell medium.Immunohistochemical staining was employed to observe tyrosine hydroxylase and AADC expression and behavioral changes were measured in Parkinson's rats.RESULTS:Transfected AAV-CreERT2 and AAV expressing dopamine synthesis enzymes could increase the synthesis of dopamine in HEK293 medium and Parkinson's rat striatum(P < 0.01) and improve the rotational behavior of Parkinson's rats.While tamoxifen markedly reduced overproduction of dopamine caused by cotransfection of viral vectors(P < 0.01),but did not affect the expression and activity of AADC.CONCLUSION:The application of AAV vector-encoded tyrosine hydroxylase gene under the gene regulation system of Cre-ERT2,after tamoxifen treatment,can effectively control the generation of genetically modified products to reduce the production of excessive dopamine in vivo and in vitro.Therefore,this method can increase the safety of gene therapy.
