The A_(2)B_(2)O_(7)-type rare earth zirconate compounds have been considered as promising candidates for thermal barrier coating(TBC) materials because of their low sintering rate,improved phase stability,and reduced ...The A_(2)B_(2)O_(7)-type rare earth zirconate compounds have been considered as promising candidates for thermal barrier coating(TBC) materials because of their low sintering rate,improved phase stability,and reduced thermal conductivity in contrast with the currently used yttria-partially stabilized zirconia (YSZ) in high operating temperature environments.This review summarizes the recent progress on rare earth zirconates for TBCs that insulate high-temperature gas from hot-section components in gas turbines.Based on the first principles,molecular dynamics,and new data-driven calculation approaches,doping and high-entropy strategies have now been adopted in advanced TBC materials design.In this paper,the solid-state heat transfer mechanism of TBCs is explained from two aspects,including heat conduction over the full operating temperature range and thermal radiation at medium and high temperature.This paper also provides new insights into design considerations of adaptive TBC materials,and the challenges and potential breakthroughs are further highlighted for extreme environmental applications.Strategies for improving thermophysical performance are proposed in two approaches:defect engineering and material compositing.展开更多
Determining the suitable areas for winter wheat under climate change and assessing the risk of freezing injury are crucial for the cultivation of winter wheat.We used an optimized Maximum Entropy(MaxEnt)Model to predi...Determining the suitable areas for winter wheat under climate change and assessing the risk of freezing injury are crucial for the cultivation of winter wheat.We used an optimized Maximum Entropy(MaxEnt)Model to predict the potential distribution of winter wheat in the current period(1970-2020)and the future period(2021-2100)under four shared socioeconomic pathway scenarios(SSPs).We applied statistical downscaling methods to downscale future climate data,established a scientific and practical freezing injury index(FII)by considering the growth period of winter wheat,and analyzed the characteristics of abrupt changes in winter wheat freezing injury by using the Mann-Kendall(M-K)test.The results showed that the prediction accuracy AUC value of the MaxEnt Model reached 0.976.The minimum temperature in the coldest month,precipitation in the wettest season and annual precipitation were the main factors affecting the spatial distribution of winter wheat.The total suitable area of winter wheat was approximately 4.40×10^(7)ha in the current period.In the 2070s,the moderately suitable areas had the greatest increase by 9.02×10^(5)ha under SSP245 and the least increase by 6.53×10^(5)ha under SSP370.The centroid coordinates of the total suitable areas tended to move northward.The potential risks of freezing injury in the high-latitude and-altitude areas of the Loess Plateau,China increased significantly.The northern areas of Xinzhou in Shanxi Province,China suffered the most serious freezing injury,and the southern areas of the Loess Plateau suffered the least.Environmental factors such as temperature,precipitation and geographical location had important impacts on the suitable area distribution and freezing injury risk of winter wheat.In the future,greater attention should be paid to the northward boundaries of both the winter wheat planting areas and the areas of freezing injury risk to provide the early warning of freezing injury and implement corresponding management strategies.展开更多
As a cell proliferation regulator involved in wide biological processes in plants,GRF-INTERACTING FACTOR(GIF)controls different tissues development.However,whether GIF participates in fruit development remains unclear...As a cell proliferation regulator involved in wide biological processes in plants,GRF-INTERACTING FACTOR(GIF)controls different tissues development.However,whether GIF participates in fruit development remains unclear.According to transcriptome data,we identified PbGIF1was highly expressed during fruit development in cytokinins induced parthenocarpy pear.In the present study,the biofunction of PbGIF1 was initially verified.Overexpression of PbGIF1 promoted fruit size of transgenic tomato.The size of flesh fruit was not affected by cell expansion but the cell proliferation was promoted by overexpressing Pb GIF1.The accelerated cell proliferation process was also observed in PbGIF1-overexpressed transgenic pear fruit calli.The transcriptional regulation of cytokinins on PbGIF1 was further confirmed by exogenous CPPU treatments in pear fruitlets.To investigate the underlying mechanism,the cytokinins-responded factor,PbRR1,was further focused on.The results of Yeast-one-hybrid assay suggested that PbRR1 can bind to the promoter sequence of PbGIF1.The transcriptional activation of PbRR1 on PbGIF1 was also confirmed by Dual-Luciferase assays.Taken together,the results showed that cytokinins control pear fruit development via the transcriptional activation of PbGIF1 by PbRR1.展开更多
α-Keggin polyoxometalates(POMs)[XW_(12)O_(40)]^(n−)(X=Al,Si,P,S)are widely used in batteries owing to their remarkable redox activity.However,the mechanism underlying the applications appears inconsistent with the wi...α-Keggin polyoxometalates(POMs)[XW_(12)O_(40)]^(n−)(X=Al,Si,P,S)are widely used in batteries owing to their remarkable redox activity.However,the mechanism underlying the applications appears inconsistent with the widely accepted covalent bonding nature.Here,first-principles calculations show that XW_(12)are core–shell structures composed of a shell and an XO_(4)^(n−)core,both are stabilized by covalent interactions.Interestingly,owing to the presence of a substantial number of electrons in W_(12)O_(36)shell,the frontier molecular orbitals of XW_(12)are not only strongly delocalized but also exhibit superatomic properties with high-angular momentum electrons that do not conform to the Jellium model.Detailed analysis indicates that energetically high lying filled molecular orbitals(MOs)have reached unusually high-angular momentum characterized by quantum number K or higher,allowing for the accommodation of numerous electrons.This attribute confers strong electron acceptor ability and redox activity to XW_(12).Moreover,electrons added to XW_(12)still occupy the K orbitals and will not cause rearrangement of the MOs,thereby maintaining the stability of these structures.Our findings highlight the structure–activity relationship and provide a direction for tailor-made POMs with specific properties at atomic level.展开更多
Heavy-fuel engines are widely used in UAVs(Unmanned Autonomous Vehicles)because of their reliability and high-power density.In this study,a combustion model for an in-cylinder direct injection engine has been imple-me...Heavy-fuel engines are widely used in UAVs(Unmanned Autonomous Vehicles)because of their reliability and high-power density.In this study,a combustion model for an in-cylinder direct injection engine has been imple-mented using the AVL FIRE software.The effects of the angle of nozzle inclination on fuel evaporation,mixture distribution,and combustion in the engine cylinder have been systematically studied at 5500 r/min and consider-ing full load cruise conditions.According to the results,as the angle of nozzle inclination increases,the maximum combustion explosion pressure in the cylinderfirst increases and then it decreases.When the angle of nozzle incli-nation is less than 45°,the quality of the mixture in the cylinder and the combustion performance can be improved by increasing the angle.When the angle of nozzle inclination is greater than 45°,however,the mixture unevenness increases slightly with the angle,leading to a deterioration of the combustion performances.When the angle of nozzle inclination is between 35°and 55°,the overall combustion performance of the engine is rela-tively good.When the angle of nozzle inclination is 45°,the combustion chamber’s geometry and the cylinder’s airflow are well matched with the fuel spray,and the mixture quality is the best.Compared with 25°,the peak heat release rate increases by 20%,and the maximum combustion burst pressure increases by 5.5%.展开更多
Nine Chinese yak breeds (Maiwa, Tianzhu White, Qinghai Plateau, Sibu, Zhongdian, Pali, Tibetan High Mountain, Jiulong, and Xinjiang) and Gayal were analyzed by means of 16 microsatellite markers to determine the lev...Nine Chinese yak breeds (Maiwa, Tianzhu White, Qinghai Plateau, Sibu, Zhongdian, Pali, Tibetan High Mountain, Jiulong, and Xinjiang) and Gayal were analyzed by means of 16 microsatellite markers to determine the level of genetic variation within populations, genetic relationship between populations, and population structure for each breed. A total of 206 microsatellite alleles were observed. Mean F-statistics (0.056) for 9 yak breeds indicated that 94.4% of the genetic variation was observed within yak breeds and 5.6% of the genetic variation existed amongst breeds. The Neighbor-Joining phylogenetic tree was constructed based on Nei's standard genetic distances and two clusters were obtained. The Gayal separated from the yaks far away and formed one cluster and 9 yak breeds were grouped together. The analysis of population structure for 9 yak breeds and the Gayal showed that they resulted in four clusters; one cluster includes yaks from Tibet Autonomous Region and Qinghai Province, one cluster combines Zhongdian, Maiwa, and Tianzhu White, and Jiulong and Xinjiang come into the third cluster. Pali was mainly in the first cluster (90%), Jiulong was mainly in the second cluster (87.1%), Zhongdian was primarily in the third cluster (83%), and the other yak breeds were distributed in two to three clusters. The Gayal was positively left in the fourth cluster (99.3%).展开更多
Phytohormones play crucial roles in fruit set regulation and development.Here,gibberellins(GA4+7),but not GA3,induced pear parthenocarpy.To systematically investigate the changes upon GA4+7 induced pear parthenocarpy,...Phytohormones play crucial roles in fruit set regulation and development.Here,gibberellins(GA4+7),but not GA3,induced pear parthenocarpy.To systematically investigate the changes upon GA4+7 induced pear parthenocarpy,dynamic changes in histology,hormone and transcript levels were observed and identified in unpollinated,pollinated and GA4+7-treated ovaries.Mesocarp cells continued developing in both GA4+7-treated and pollinated ovaries.In unpollinated ovaries,mesocarp cells stopped developing 14 days after anthesis.During fruit set process,GA4+7,but not GA1+3,increased after pollination.Abscisic acid(ABA)accumulation was significantly repressed by GA4+7 or pollination,but under unpollinated conditions,ABA was produced in large quantities.Moreover,indole-3-acetic acid biosynthesis was not induced by GA4+7 or pollination treatments.Details of this GA–auxin–ABA cross-linked gene network were determined by a comparative transcriptome analysis.The indole-3-acetic acid transport-related genes,mainly auxin efflux carrier component genes,were induced in both GA4+7-treated and pollinated ovaries.ABA biosynthetic genes of the 9-cis-epoxycarotenoid dioxygenase family were repressed by GA4+7 and pollination.Moreover,directly related genes in the downstream parthenocarpy network involved in cell division and expansion(upregulated),and MADS-box family genes(downregulated),were also identified.Thus,a model of GA-induced hormonal balance and its effects on parthenocarpy were established.展开更多
The protection of drinking water sources is vital to urban development and public health.In this study,the current situation of the mandatory protection area for drinking water source in the Pearl River Delta region w...The protection of drinking water sources is vital to urban development and public health.In this study,the current situation of the mandatory protection area for drinking water source in the Pearl River Delta region was investigated using a method combining Google Earth with the field survey.The gaps between management practices and legislation requirements were analyzed.Finally,several countermeasures for water resource protection were proposed as follows:to promote delineation in a more scientific way,to safeguard the sanctity of the law,to make better plan on water saving,and to encourage public participation in supervision and management.展开更多
With the application of UAVs in intelligent transportation systems, vehicle detection for aerial images has become a key engineering technology and has academic research significance. In this paper, a vehicle detectio...With the application of UAVs in intelligent transportation systems, vehicle detection for aerial images has become a key engineering technology and has academic research significance. In this paper, a vehicle detection method for aerial image based on YOLO deep learning algorithm is presented. The method integrates an aerial image dataset suitable for YOLO training by pro-cessing three public aerial image datasets. Experiments show that the training model has a good performance on unknown aerial images, especially for small objects, rotating objects, as well as compact and dense objects, while meeting the real-time requirements.展开更多
BACKGROUND: Studies have demonstrated that ultrasound-mediated microbubble destruction significantly improves transfection efficiency of enhanced green fluorescent protein (EGFP) in in vitro cultured retinal gangli...BACKGROUND: Studies have demonstrated that ultrasound-mediated microbubble destruction significantly improves transfection efficiency of enhanced green fluorescent protein (EGFP) in in vitro cultured retinal ganglial cells (RGCs). OBJECTIVE: To investigate the feasibility of ultrasound-mediated microbubble destruction for EGFP transfection in rat RGCs, and to compare efficiency and cell damage with traditional transfection methods. DESIGN, TIME AND SETTING: In vivo, gene engineering experiment. The study was performed at the Central Laboratory, Institute of Ultrasonic Imaging, Chongqing Medical University from March to July 2008. MATERIALS: Eukaryotic expression vector plasmid EGFP and microbubbles were prepared by the Institute of Ultrasonic Imaging, Chongqing Medical University. The microbubbles were produced at a concentration of 8.7 × 10^11/L, with a 2-4 μm diameter, and 10-hour half-life in vitro. METHODS: A total of 50 Sprague Dawley rats were randomly assigned to four groups. Normal controls (n = 5) were infused with 5 μL normal saline to the vitreous cavity; the naked plasmid group (n = 15) was infused with 5 pL EGFP plasmid to the vitreous cavity; in the plasmid with ultrasound group (n = 15), the eyes were irradiated with low-energy ultrasound wave (0.5 W/cm^2) for a total of 60 seconds (irradiated for 5 seconds, at 10-second intervals) immediately following infusion of EGFP plasmids to the vitreous cavities. In the microbubble-ultrasound group (n = 15), the eyes were irradiated with the same power of ultrasonic wave immediately following infusion of microbubbles containing EGFP plasmids to the vitreous cavities. MAIN OUTCOME MEASURES: After 7 days, retinal preparations and EGFP expression in RGCs were observed by fluorescence microscopy. RGC quantification in the retinal ganglion cell layer was performed. In addition, EGFP mRNA expression was semi-quantitatively determined by RT-PCR. RESULTS: The transfection efficiency of EGFP to RGCs by microbubbles with ultrasound was significantly greater than the other groups, and no obvious damage was detected in the RGCs. CONCLUSION: Under irradiation of low-frequency ultrasound waves, ultrasound-mediated microbubble destruction was effective and resulted in safe transfection of the EGFP gene to the RGCs.展开更多
Fruit with stripes,which are generally longitudinal,can occur naturally,but the bioprocesses underlying this phenomenon are unclear.Previously,we observed an atypical anthocyanin distribution that caused red-striped f...Fruit with stripes,which are generally longitudinal,can occur naturally,but the bioprocesses underlying this phenomenon are unclear.Previously,we observed an atypical anthocyanin distribution that caused red-striped fruit on the spontaneous pear bud sport“Red Zaosu”(Pyrus bretschneideri Rehd.).In this study,comparative transcriptome analysis of the sport and wild-type“Zaosu”revealed that this atypical anthocyanin accumulation was tightly correlated with abnormal overexpression of the gene-encoding gibberellin(GA)2-beta-dioxygenase 8,PbGA2ox8.Consistently,decreased methylation was also observed in the promoter region of PbGA2ox8 from“Red Zaosu”compared with“Zaosu”.Moreover,the GA levels in“Red Zaosu”seedlings were lower than those in“Zaosu”seedlings,and the application of exogenous GA4 reduced abnormal anthocyanin accumulation in“Red Zaosu”.Transient overexpression of PbGA2ox8 reduced the GA4 level and caused anthocyanin accumulation in pear fruit skin.Moreover,the presence of red stripes indicated anthocyanin accumulation in the hypanthial epidermal layer near vascular branches(VBs)in“Red Zaosu”.Transient overexpression of PbGA2ox8 resulting from vacuum infiltration induced anthocyanin accumulation preferentially in calcium-enriched areas near the vascular bundles in pear leaves.We propose a fruit-striping mechanism,in which the abnormal overexpression of PbGA2ox8 in“Red Zaosu”induces the formation of a longitudinal array of anthocyanin stripes near vascular bundles in fruit.展开更多
Numerous environmental and endogenous signals control the highly orchestrated and intricate process of plant senescence.Ethylene,a well-known inducer of senescence,has long been considered a key endogenous regulator o...Numerous environmental and endogenous signals control the highly orchestrated and intricate process of plant senescence.Ethylene,a well-known inducer of senescence,has long been considered a key endogenous regulator of leaf and flower senescence,but the molecular mechanism of ethylene-induced ovule senescence has not yet been elucidated.In this study,we found that blockage of fertilization caused ovule abortion in the pear cultivar‘1913’.According to transcriptome and phytohormone content data,ethylene biosynthesis was activated by pollination.At the same time,ethylene overaccumulated in ovules,where cells were sensitive to ethylene signals in the absence of fertilization.We identified a transcription factor in the ethylene signal response,ethylene-insensitive 3-like(EIL1),as a likely participant in ovule senescence.Overexpression of PbEIL1 in tomato caused precocious onset of ovule senescence.We further found that EIL1 could directly bind to the promoter of the SENESCENCE-ASSOCIATED CYSTEINE PROTEINASE 1(PbCysp1)gene and act upstream of senescence.Yeast one-hybrid and dual-luciferase assays revealed the interaction of the transcription factor and the promoter DNA sequence and demonstrated that PbEIL1 enhanced the action of PbCysp1.Collectively,our results provide new insights into how ethylene promotes the progression of unfertilized ovule senescence.展开更多
Parthenocarpy is a valuable trait in self-incompatible plants,such as pear.N-(2-chloro-4-pyridyl)-N’-phenylurea(CPPU),a synthetic cytokinin analog,can induce parthenocarpy in pear(Pyrus spp.),but the mechanism of ind...Parthenocarpy is a valuable trait in self-incompatible plants,such as pear.N-(2-chloro-4-pyridyl)-N’-phenylurea(CPPU),a synthetic cytokinin analog,can induce parthenocarpy in pear(Pyrus spp.),but the mechanism of induction is unclear.To investigate the role of gibberellin in CPPU-induced parthenocarpy in pear,CPPU supplemented with paclobutrazol(PAC)was sprayed onto‘Dangshansu’pear.We found that the fruit set rate of pear treated with CPPU supplemented with PAC was identical to that in a CPPU-alone treatment group.In regard to cell development,CPPU mainly promoted hypanthium cell division and expansion,and PAC application had no influence on CPPU-induced cell development.RNA sequencing revealed that gibberellin 20 oxidase and gibberellin 3 oxidase genes were not differentially expressed following CPPU treatment.According to the analysis of fruit phytohormone content,the CPPU treatments did not induce gibberellin biosynthesis.These results suggest that CPPU-induced parthenocarpy may be gibberellin independent in‘Dangshansu’pear.After CPPU treatment,the indole acetic acid(IAA)content in fruit was significantly increased,and the abscisic acid(ABA)content was significantly decreased.Similarly,RNA sequencing revealed that many genes involved in the auxin and ABA pathways were significantly differentially expressed in the CPPU treatment groups;among them,indole-3-pyruvate monooxygenase(YUCCA)was significantly upregulated and 9-cis-epoxycarotenoid dioxygenase(NCED)was significantly downregulated.IAA and ABA may thus play important roles in CPPU-induced parthenocarpy.PbTwo-component response regulator9(PbRR9),PbYUCCA4,and PbNCED6 were then selected to further elucidate the mechanism of CPPU-induced parthenocarpy.A yeast one-hybrid assay indicated that PbRR9 can combine with the PbYUCCA4 and PbNCED6 promoters.Dual luciferase assays revealed that PbRR9 can promote and repress the activities of the PbYUCCA4 and PbNCED6 promoters,respectively.After the transient expression of PbRR9 in fruits,PbYUCCA4 expression was significantly upregulated,and PbNCED6 expression was significantly downregulated.This study uncovered a CPPU-induced parthenocarpy mechanism that is different from that in tomato.CPPU may upregulate PbYUCCA4 and downregulate PbNCED6 by upregulating PbRR9,thereby increasing IAA content and decreasing ABA content to ultimately induce parthenocarpy in‘Dangshansu’pear.However,because only a single time point was used and because‘botanical’and‘accessory’fruits have different structures,this conclusion is still preliminary.展开更多
A hydrogen evolution-assisted one-pot aqueous approach was developed for facile synthesis of trimetallic Pd Ni Ru alloy nanochain-like networks(Pd Ni Ru NCNs) by only using KBHas the reductant, without any specific ...A hydrogen evolution-assisted one-pot aqueous approach was developed for facile synthesis of trimetallic Pd Ni Ru alloy nanochain-like networks(Pd Ni Ru NCNs) by only using KBHas the reductant, without any specific additive(e.g. surfactant, polymer, template or seed). The products were mainly investigated by transmission electron microscopy(TEM), X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS). The hierarchical architectures were formed by the oriented assembly growth and the diffusioncontrolled deposition in the presence of many in-situ generated hydrogen bubbles. The architectures had the largest electrochemically active surface area(ECSA) of 84.32 mgPdthan Pd Ni nanoparticles(NPs,65.23 mgPd), Pd Ru NPs(23.12 mgPd), Ni Ru NPs(nearly zero), and commercial Pd black(6.01 mgPd), outperforming the referenced catalysts regarding the catalytic characters for hydrazine oxygen reaction(HOR). The synthetic route provides new insight into the preparation of other trimetallic nanocatalysts in fuel cells.展开更多
Arbuscular mycorrhizal(AM)fungi can successfully enhance photosynthesis(P_(n))and plants growth in agricultural or grassland ecosystems.However,how the symbionts affect species restoration in sunlight-intensive areas ...Arbuscular mycorrhizal(AM)fungi can successfully enhance photosynthesis(P_(n))and plants growth in agricultural or grassland ecosystems.However,how the symbionts affect species restoration in sunlight-intensive areas remains largely unexplored.Therefore,this study’s objective was to assess the effect of AM fungi on apricot seedling physiology,within a specific time period,in northwest China.In 2010,an experimental field was established in Shaanxi Province,northwest China.The experimental treatments included two AM fungi inoculation levels(0 or 100 g of AM fungal inoculum per seedling),three shade levels(1900,1100,and 550µmol m^(−2) s^(−1)),and three ages(1,3,and 5 years)of transplantation.We examined growth,Pn,and morphological indicators of apricot(Prunus sibirica L.)seedling performances in 2011,2013,and 2015.The colonization rate in mycorrhizal seedlings with similar amounts of shade is higher than the corresponding controls.The mycorrhizal seedling biomass is significantly higher than the corresponding non-mycorrhizal seedling biomass.Generally,P_(n),stomatal conductance(G_(s)),transpiration rate(T_(r)),and water use efficiency are also significantly higher in the mycorrhizal seedlings.Moreover,mycorrhizal seedlings with light shade(LS)have the highest Pn.WUE is increased in non-mycorrhizal seedlings because of the reduction in T_(r),while T_(r) is increased in mycorrhizal seedlings with shade.There is a significant increase in the N,P,and K fractions detected in roots compared with shoots.This means that LS had apparent benefits for mycorrhizal seedlings.Our results also indicate that AM fungi,combined with LS,exert a positive effect on apricot behavior.展开更多
A novel structure is proposed for doubling the vertical breakdown voltage of silicon-on-insulator(SOI) devices. In this new structure, the conventional buried oxide(BOX) in an SOI device is split into two sections...A novel structure is proposed for doubling the vertical breakdown voltage of silicon-on-insulator(SOI) devices. In this new structure, the conventional buried oxide(BOX) in an SOI device is split into two sections: the source-section BOX and the drain-section BOX. A highly-doped Si layer, referred to as a non-depletion potential-clamped layer(NPCL), is positioned under and close to the two BOX sections. In the split BOXes and the Si region above the BOXes, the blocking voltage(BV) is divided into two parts by the NPCL. The voltage in the NPCL is clamped to be nearly half of the drain voltage. When the drain voltage approaches a breakdown value, the voltage sustained by the source-section BOX and the Si region under the source are nearly the same as the voltage sustained by the drain-section BOX and the Si region under the drain. The vertical BV is therefore almost doubled. The effectiveness of this new structure was verified for a P-channel SOI lateral double-diffused metal-oxide semiconductor(LDMOS) and can be applied to other high-voltage SOI devices. The simulation results show that the BV in an NPCL P-channel SOI LDMOS is improved by 55% and the specific on-resistance(Ron,sp) is reduced by 69% in comparison to the conventional structure.展开更多
Developing accurate self-assembly is the key for constructing functional materials from a bottom-up approach.At present, it is mainly hindered by building blocks and driving modes. We design a new self-assembly method...Developing accurate self-assembly is the key for constructing functional materials from a bottom-up approach.At present, it is mainly hindered by building blocks and driving modes. We design a new self-assembly method based on the magnetic coupling between spin-polarized electrons. First-principles calculations show that spinpolarized electrons from different endohedral metallofullerene(EMF) superatoms can pair each other to ensure a one-dimensional extending morphology. Furthermore, without ligand passivation, the EMF superatoms maintain their electronic structures robustly in self-assembly owing to the core-shell structure and the atomic-like electron arrangement rule. Therefore, it should noted that the magnetic coupling of monomeric electron spin polarization can be an important driving mechanism for high-precision self-assembly. These results represent a new paradigm for self-assembly and offer fresh opportunities for functional material construction at the atomic level.展开更多
Different temperatures of water bath was used to extract the intracellular microcystin-LR(MC-LR) of Microcystis aeruginosa. Researching the extraction efficiency under the suitable temperature, so that it could find o...Different temperatures of water bath was used to extract the intracellular microcystin-LR(MC-LR) of Microcystis aeruginosa. Researching the extraction efficiency under the suitable temperature, so that it could find out the best temperature and time for extracting MC-LR from Microcystis aeruginosa cells. Five equal Microcystis aeruginosa was used to find out the best temperature, extracting at 60℃, 70℃, 80℃, 90℃ and 100℃ for 15 minutes, respectively. Results showed that the content of MC-LR extracted with the water under 100℃ was the highest. But meanwhile, the type and the content of impurities was the highest, too. In addition, another six equal Microcystis aeruginosa was extract with the water under 100℃ for 5min, 10 min, 15 min, 20 min, 25 min and 30 min respectively. It was proved that 20 minutes was enough for extracting MC-LR from Microcystis aeruginosa, no long time was needed.展开更多
The 4-hydroxy-flavonoid compound luteolin is a phytoestrogen with antioxidant, anti-inflammatory, and anti-tumor properties. The present study analyzed the protective effects of luteolin against rotenone-induced PC12 ...The 4-hydroxy-flavonoid compound luteolin is a phytoestrogen with antioxidant, anti-inflammatory, and anti-tumor properties. The present study analyzed the protective effects of luteolin against rotenone-induced PC12 cell apoptosis in a model of Parkinson's disease (PD). Rotenone (1.6 μmol/L) was utilized to establish the In vitro PD model, resulting in low cell viability and an apoptotic rate of 36.1%. Luteolin (100 μmol/L) pretreatment significantly ameliorated rotenone-induced damage, improved cell morphology and viability, decreased comet tail length, reduced the rate of apoptosis (11.8%), and down-regulated cleaved caspase-3 expression. Results demonstrate that luteolin protects PC12 cells against rotenone-induced apoptosis by decreasing cleaved caspase-3 expression.展开更多
基金the financial support from the National Natural Science Foundation of China(Nos.51572061,51621091,and 51321061)the Heilongjiang Touyan Team Program。
文摘The A_(2)B_(2)O_(7)-type rare earth zirconate compounds have been considered as promising candidates for thermal barrier coating(TBC) materials because of their low sintering rate,improved phase stability,and reduced thermal conductivity in contrast with the currently used yttria-partially stabilized zirconia (YSZ) in high operating temperature environments.This review summarizes the recent progress on rare earth zirconates for TBCs that insulate high-temperature gas from hot-section components in gas turbines.Based on the first principles,molecular dynamics,and new data-driven calculation approaches,doping and high-entropy strategies have now been adopted in advanced TBC materials design.In this paper,the solid-state heat transfer mechanism of TBCs is explained from two aspects,including heat conduction over the full operating temperature range and thermal radiation at medium and high temperature.This paper also provides new insights into design considerations of adaptive TBC materials,and the challenges and potential breakthroughs are further highlighted for extreme environmental applications.Strategies for improving thermophysical performance are proposed in two approaches:defect engineering and material compositing.
基金supported by the National Natural Science Foundation of China(31201168)the Basic Research Program of Shanxi Province,China(20210302123411)the earmarked fund for Modern Agro-industry Technology Research System,China(2022-07).
文摘Determining the suitable areas for winter wheat under climate change and assessing the risk of freezing injury are crucial for the cultivation of winter wheat.We used an optimized Maximum Entropy(MaxEnt)Model to predict the potential distribution of winter wheat in the current period(1970-2020)and the future period(2021-2100)under four shared socioeconomic pathway scenarios(SSPs).We applied statistical downscaling methods to downscale future climate data,established a scientific and practical freezing injury index(FII)by considering the growth period of winter wheat,and analyzed the characteristics of abrupt changes in winter wheat freezing injury by using the Mann-Kendall(M-K)test.The results showed that the prediction accuracy AUC value of the MaxEnt Model reached 0.976.The minimum temperature in the coldest month,precipitation in the wettest season and annual precipitation were the main factors affecting the spatial distribution of winter wheat.The total suitable area of winter wheat was approximately 4.40×10^(7)ha in the current period.In the 2070s,the moderately suitable areas had the greatest increase by 9.02×10^(5)ha under SSP245 and the least increase by 6.53×10^(5)ha under SSP370.The centroid coordinates of the total suitable areas tended to move northward.The potential risks of freezing injury in the high-latitude and-altitude areas of the Loess Plateau,China increased significantly.The northern areas of Xinzhou in Shanxi Province,China suffered the most serious freezing injury,and the southern areas of the Loess Plateau suffered the least.Environmental factors such as temperature,precipitation and geographical location had important impacts on the suitable area distribution and freezing injury risk of winter wheat.In the future,greater attention should be paid to the northward boundaries of both the winter wheat planting areas and the areas of freezing injury risk to provide the early warning of freezing injury and implement corresponding management strategies.
基金supported by the China Agriculture Research System of MOF and MARA。
文摘As a cell proliferation regulator involved in wide biological processes in plants,GRF-INTERACTING FACTOR(GIF)controls different tissues development.However,whether GIF participates in fruit development remains unclear.According to transcriptome data,we identified PbGIF1was highly expressed during fruit development in cytokinins induced parthenocarpy pear.In the present study,the biofunction of PbGIF1 was initially verified.Overexpression of PbGIF1 promoted fruit size of transgenic tomato.The size of flesh fruit was not affected by cell expansion but the cell proliferation was promoted by overexpressing Pb GIF1.The accelerated cell proliferation process was also observed in PbGIF1-overexpressed transgenic pear fruit calli.The transcriptional regulation of cytokinins on PbGIF1 was further confirmed by exogenous CPPU treatments in pear fruitlets.To investigate the underlying mechanism,the cytokinins-responded factor,PbRR1,was further focused on.The results of Yeast-one-hybrid assay suggested that PbRR1 can bind to the promoter sequence of PbGIF1.The transcriptional activation of PbRR1 on PbGIF1 was also confirmed by Dual-Luciferase assays.Taken together,the results showed that cytokinins control pear fruit development via the transcriptional activation of PbGIF1 by PbRR1.
基金supported by the National Natural Science Foundation of China(under grant numbers 12174272 and 11974136)。
文摘α-Keggin polyoxometalates(POMs)[XW_(12)O_(40)]^(n−)(X=Al,Si,P,S)are widely used in batteries owing to their remarkable redox activity.However,the mechanism underlying the applications appears inconsistent with the widely accepted covalent bonding nature.Here,first-principles calculations show that XW_(12)are core–shell structures composed of a shell and an XO_(4)^(n−)core,both are stabilized by covalent interactions.Interestingly,owing to the presence of a substantial number of electrons in W_(12)O_(36)shell,the frontier molecular orbitals of XW_(12)are not only strongly delocalized but also exhibit superatomic properties with high-angular momentum electrons that do not conform to the Jellium model.Detailed analysis indicates that energetically high lying filled molecular orbitals(MOs)have reached unusually high-angular momentum characterized by quantum number K or higher,allowing for the accommodation of numerous electrons.This attribute confers strong electron acceptor ability and redox activity to XW_(12).Moreover,electrons added to XW_(12)still occupy the K orbitals and will not cause rearrangement of the MOs,thereby maintaining the stability of these structures.Our findings highlight the structure–activity relationship and provide a direction for tailor-made POMs with specific properties at atomic level.
文摘Heavy-fuel engines are widely used in UAVs(Unmanned Autonomous Vehicles)because of their reliability and high-power density.In this study,a combustion model for an in-cylinder direct injection engine has been imple-mented using the AVL FIRE software.The effects of the angle of nozzle inclination on fuel evaporation,mixture distribution,and combustion in the engine cylinder have been systematically studied at 5500 r/min and consider-ing full load cruise conditions.According to the results,as the angle of nozzle inclination increases,the maximum combustion explosion pressure in the cylinderfirst increases and then it decreases.When the angle of nozzle incli-nation is less than 45°,the quality of the mixture in the cylinder and the combustion performance can be improved by increasing the angle.When the angle of nozzle inclination is greater than 45°,however,the mixture unevenness increases slightly with the angle,leading to a deterioration of the combustion performances.When the angle of nozzle inclination is between 35°and 55°,the overall combustion performance of the engine is rela-tively good.When the angle of nozzle inclination is 45°,the combustion chamber’s geometry and the cylinder’s airflow are well matched with the fuel spray,and the mixture quality is the best.Compared with 25°,the peak heat release rate increases by 20%,and the maximum combustion burst pressure increases by 5.5%.
文摘Nine Chinese yak breeds (Maiwa, Tianzhu White, Qinghai Plateau, Sibu, Zhongdian, Pali, Tibetan High Mountain, Jiulong, and Xinjiang) and Gayal were analyzed by means of 16 microsatellite markers to determine the level of genetic variation within populations, genetic relationship between populations, and population structure for each breed. A total of 206 microsatellite alleles were observed. Mean F-statistics (0.056) for 9 yak breeds indicated that 94.4% of the genetic variation was observed within yak breeds and 5.6% of the genetic variation existed amongst breeds. The Neighbor-Joining phylogenetic tree was constructed based on Nei's standard genetic distances and two clusters were obtained. The Gayal separated from the yaks far away and formed one cluster and 9 yak breeds were grouped together. The analysis of population structure for 9 yak breeds and the Gayal showed that they resulted in four clusters; one cluster includes yaks from Tibet Autonomous Region and Qinghai Province, one cluster combines Zhongdian, Maiwa, and Tianzhu White, and Jiulong and Xinjiang come into the third cluster. Pali was mainly in the first cluster (90%), Jiulong was mainly in the second cluster (87.1%), Zhongdian was primarily in the third cluster (83%), and the other yak breeds were distributed in two to three clusters. The Gayal was positively left in the fourth cluster (99.3%).
基金This work was supported by the China Agriculture Research System(CARS-29-40)Weinan Experimental Station foundation of Northwest A&F University.
文摘Phytohormones play crucial roles in fruit set regulation and development.Here,gibberellins(GA4+7),but not GA3,induced pear parthenocarpy.To systematically investigate the changes upon GA4+7 induced pear parthenocarpy,dynamic changes in histology,hormone and transcript levels were observed and identified in unpollinated,pollinated and GA4+7-treated ovaries.Mesocarp cells continued developing in both GA4+7-treated and pollinated ovaries.In unpollinated ovaries,mesocarp cells stopped developing 14 days after anthesis.During fruit set process,GA4+7,but not GA1+3,increased after pollination.Abscisic acid(ABA)accumulation was significantly repressed by GA4+7 or pollination,but under unpollinated conditions,ABA was produced in large quantities.Moreover,indole-3-acetic acid biosynthesis was not induced by GA4+7 or pollination treatments.Details of this GA–auxin–ABA cross-linked gene network were determined by a comparative transcriptome analysis.The indole-3-acetic acid transport-related genes,mainly auxin efflux carrier component genes,were induced in both GA4+7-treated and pollinated ovaries.ABA biosynthetic genes of the 9-cis-epoxycarotenoid dioxygenase family were repressed by GA4+7 and pollination.Moreover,directly related genes in the downstream parthenocarpy network involved in cell division and expansion(upregulated),and MADS-box family genes(downregulated),were also identified.Thus,a model of GA-induced hormonal balance and its effects on parthenocarpy were established.
文摘The protection of drinking water sources is vital to urban development and public health.In this study,the current situation of the mandatory protection area for drinking water source in the Pearl River Delta region was investigated using a method combining Google Earth with the field survey.The gaps between management practices and legislation requirements were analyzed.Finally,several countermeasures for water resource protection were proposed as follows:to promote delineation in a more scientific way,to safeguard the sanctity of the law,to make better plan on water saving,and to encourage public participation in supervision and management.
文摘With the application of UAVs in intelligent transportation systems, vehicle detection for aerial images has become a key engineering technology and has academic research significance. In this paper, a vehicle detection method for aerial image based on YOLO deep learning algorithm is presented. The method integrates an aerial image dataset suitable for YOLO training by pro-cessing three public aerial image datasets. Experiments show that the training model has a good performance on unknown aerial images, especially for small objects, rotating objects, as well as compact and dense objects, while meeting the real-time requirements.
基金the National Natural Science Foundation of China,No.30430230
文摘BACKGROUND: Studies have demonstrated that ultrasound-mediated microbubble destruction significantly improves transfection efficiency of enhanced green fluorescent protein (EGFP) in in vitro cultured retinal ganglial cells (RGCs). OBJECTIVE: To investigate the feasibility of ultrasound-mediated microbubble destruction for EGFP transfection in rat RGCs, and to compare efficiency and cell damage with traditional transfection methods. DESIGN, TIME AND SETTING: In vivo, gene engineering experiment. The study was performed at the Central Laboratory, Institute of Ultrasonic Imaging, Chongqing Medical University from March to July 2008. MATERIALS: Eukaryotic expression vector plasmid EGFP and microbubbles were prepared by the Institute of Ultrasonic Imaging, Chongqing Medical University. The microbubbles were produced at a concentration of 8.7 × 10^11/L, with a 2-4 μm diameter, and 10-hour half-life in vitro. METHODS: A total of 50 Sprague Dawley rats were randomly assigned to four groups. Normal controls (n = 5) were infused with 5 μL normal saline to the vitreous cavity; the naked plasmid group (n = 15) was infused with 5 pL EGFP plasmid to the vitreous cavity; in the plasmid with ultrasound group (n = 15), the eyes were irradiated with low-energy ultrasound wave (0.5 W/cm^2) for a total of 60 seconds (irradiated for 5 seconds, at 10-second intervals) immediately following infusion of EGFP plasmids to the vitreous cavities. In the microbubble-ultrasound group (n = 15), the eyes were irradiated with the same power of ultrasonic wave immediately following infusion of microbubbles containing EGFP plasmids to the vitreous cavities. MAIN OUTCOME MEASURES: After 7 days, retinal preparations and EGFP expression in RGCs were observed by fluorescence microscopy. RGC quantification in the retinal ganglion cell layer was performed. In addition, EGFP mRNA expression was semi-quantitatively determined by RT-PCR. RESULTS: The transfection efficiency of EGFP to RGCs by microbubbles with ultrasound was significantly greater than the other groups, and no obvious damage was detected in the RGCs. CONCLUSION: Under irradiation of low-frequency ultrasound waves, ultrasound-mediated microbubble destruction was effective and resulted in safe transfection of the EGFP gene to the RGCs.
基金supported by the National Natural Science Foundation of China(31572086,31171925,and 31401845)the China Agriculture Research System(CARS 28-45).
文摘Fruit with stripes,which are generally longitudinal,can occur naturally,but the bioprocesses underlying this phenomenon are unclear.Previously,we observed an atypical anthocyanin distribution that caused red-striped fruit on the spontaneous pear bud sport“Red Zaosu”(Pyrus bretschneideri Rehd.).In this study,comparative transcriptome analysis of the sport and wild-type“Zaosu”revealed that this atypical anthocyanin accumulation was tightly correlated with abnormal overexpression of the gene-encoding gibberellin(GA)2-beta-dioxygenase 8,PbGA2ox8.Consistently,decreased methylation was also observed in the promoter region of PbGA2ox8 from“Red Zaosu”compared with“Zaosu”.Moreover,the GA levels in“Red Zaosu”seedlings were lower than those in“Zaosu”seedlings,and the application of exogenous GA4 reduced abnormal anthocyanin accumulation in“Red Zaosu”.Transient overexpression of PbGA2ox8 reduced the GA4 level and caused anthocyanin accumulation in pear fruit skin.Moreover,the presence of red stripes indicated anthocyanin accumulation in the hypanthial epidermal layer near vascular branches(VBs)in“Red Zaosu”.Transient overexpression of PbGA2ox8 resulting from vacuum infiltration induced anthocyanin accumulation preferentially in calcium-enriched areas near the vascular bundles in pear leaves.We propose a fruit-striping mechanism,in which the abnormal overexpression of PbGA2ox8 in“Red Zaosu”induces the formation of a longitudinal array of anthocyanin stripes near vascular bundles in fruit.
基金the National Key R&D Program of China(2019YFD1001400)the China Agriculture Research System(CARS 28-45).
文摘Numerous environmental and endogenous signals control the highly orchestrated and intricate process of plant senescence.Ethylene,a well-known inducer of senescence,has long been considered a key endogenous regulator of leaf and flower senescence,but the molecular mechanism of ethylene-induced ovule senescence has not yet been elucidated.In this study,we found that blockage of fertilization caused ovule abortion in the pear cultivar‘1913’.According to transcriptome and phytohormone content data,ethylene biosynthesis was activated by pollination.At the same time,ethylene overaccumulated in ovules,where cells were sensitive to ethylene signals in the absence of fertilization.We identified a transcription factor in the ethylene signal response,ethylene-insensitive 3-like(EIL1),as a likely participant in ovule senescence.Overexpression of PbEIL1 in tomato caused precocious onset of ovule senescence.We further found that EIL1 could directly bind to the promoter of the SENESCENCE-ASSOCIATED CYSTEINE PROTEINASE 1(PbCysp1)gene and act upstream of senescence.Yeast one-hybrid and dual-luciferase assays revealed the interaction of the transcription factor and the promoter DNA sequence and demonstrated that PbEIL1 enhanced the action of PbCysp1.Collectively,our results provide new insights into how ethylene promotes the progression of unfertilized ovule senescence.
基金supported by the China Agriculture Research System(CARS-28-45)the Primary Research and Development Plan of Shaanxi Province(2017NY-029).
文摘Parthenocarpy is a valuable trait in self-incompatible plants,such as pear.N-(2-chloro-4-pyridyl)-N’-phenylurea(CPPU),a synthetic cytokinin analog,can induce parthenocarpy in pear(Pyrus spp.),but the mechanism of induction is unclear.To investigate the role of gibberellin in CPPU-induced parthenocarpy in pear,CPPU supplemented with paclobutrazol(PAC)was sprayed onto‘Dangshansu’pear.We found that the fruit set rate of pear treated with CPPU supplemented with PAC was identical to that in a CPPU-alone treatment group.In regard to cell development,CPPU mainly promoted hypanthium cell division and expansion,and PAC application had no influence on CPPU-induced cell development.RNA sequencing revealed that gibberellin 20 oxidase and gibberellin 3 oxidase genes were not differentially expressed following CPPU treatment.According to the analysis of fruit phytohormone content,the CPPU treatments did not induce gibberellin biosynthesis.These results suggest that CPPU-induced parthenocarpy may be gibberellin independent in‘Dangshansu’pear.After CPPU treatment,the indole acetic acid(IAA)content in fruit was significantly increased,and the abscisic acid(ABA)content was significantly decreased.Similarly,RNA sequencing revealed that many genes involved in the auxin and ABA pathways were significantly differentially expressed in the CPPU treatment groups;among them,indole-3-pyruvate monooxygenase(YUCCA)was significantly upregulated and 9-cis-epoxycarotenoid dioxygenase(NCED)was significantly downregulated.IAA and ABA may thus play important roles in CPPU-induced parthenocarpy.PbTwo-component response regulator9(PbRR9),PbYUCCA4,and PbNCED6 were then selected to further elucidate the mechanism of CPPU-induced parthenocarpy.A yeast one-hybrid assay indicated that PbRR9 can combine with the PbYUCCA4 and PbNCED6 promoters.Dual luciferase assays revealed that PbRR9 can promote and repress the activities of the PbYUCCA4 and PbNCED6 promoters,respectively.After the transient expression of PbRR9 in fruits,PbYUCCA4 expression was significantly upregulated,and PbNCED6 expression was significantly downregulated.This study uncovered a CPPU-induced parthenocarpy mechanism that is different from that in tomato.CPPU may upregulate PbYUCCA4 and downregulate PbNCED6 by upregulating PbRR9,thereby increasing IAA content and decreasing ABA content to ultimately induce parthenocarpy in‘Dangshansu’pear.However,because only a single time point was used and because‘botanical’and‘accessory’fruits have different structures,this conclusion is still preliminary.
基金financially supported by the Nation Natural Science Foundation of China(No.21475118)
文摘A hydrogen evolution-assisted one-pot aqueous approach was developed for facile synthesis of trimetallic Pd Ni Ru alloy nanochain-like networks(Pd Ni Ru NCNs) by only using KBHas the reductant, without any specific additive(e.g. surfactant, polymer, template or seed). The products were mainly investigated by transmission electron microscopy(TEM), X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS). The hierarchical architectures were formed by the oriented assembly growth and the diffusioncontrolled deposition in the presence of many in-situ generated hydrogen bubbles. The architectures had the largest electrochemically active surface area(ECSA) of 84.32 mgPdthan Pd Ni nanoparticles(NPs,65.23 mgPd), Pd Ru NPs(23.12 mgPd), Ni Ru NPs(nearly zero), and commercial Pd black(6.01 mgPd), outperforming the referenced catalysts regarding the catalytic characters for hydrazine oxygen reaction(HOR). The synthetic route provides new insight into the preparation of other trimetallic nanocatalysts in fuel cells.
基金the National Natural Science Foundation of China(51974326)Capital Science and Technology Talents Training Project(Beijing)(Z18110006318021).
文摘Arbuscular mycorrhizal(AM)fungi can successfully enhance photosynthesis(P_(n))and plants growth in agricultural or grassland ecosystems.However,how the symbionts affect species restoration in sunlight-intensive areas remains largely unexplored.Therefore,this study’s objective was to assess the effect of AM fungi on apricot seedling physiology,within a specific time period,in northwest China.In 2010,an experimental field was established in Shaanxi Province,northwest China.The experimental treatments included two AM fungi inoculation levels(0 or 100 g of AM fungal inoculum per seedling),three shade levels(1900,1100,and 550µmol m^(−2) s^(−1)),and three ages(1,3,and 5 years)of transplantation.We examined growth,Pn,and morphological indicators of apricot(Prunus sibirica L.)seedling performances in 2011,2013,and 2015.The colonization rate in mycorrhizal seedlings with similar amounts of shade is higher than the corresponding controls.The mycorrhizal seedling biomass is significantly higher than the corresponding non-mycorrhizal seedling biomass.Generally,P_(n),stomatal conductance(G_(s)),transpiration rate(T_(r)),and water use efficiency are also significantly higher in the mycorrhizal seedlings.Moreover,mycorrhizal seedlings with light shade(LS)have the highest Pn.WUE is increased in non-mycorrhizal seedlings because of the reduction in T_(r),while T_(r) is increased in mycorrhizal seedlings with shade.There is a significant increase in the N,P,and K fractions detected in roots compared with shoots.This means that LS had apparent benefits for mycorrhizal seedlings.Our results also indicate that AM fungi,combined with LS,exert a positive effect on apricot behavior.
基金supported by the National Natural Science Foundation of China(Grant No.61404110)the National Higher-Education Institution General Research and Development Project,China(Grant No.2682014CX097)
文摘A novel structure is proposed for doubling the vertical breakdown voltage of silicon-on-insulator(SOI) devices. In this new structure, the conventional buried oxide(BOX) in an SOI device is split into two sections: the source-section BOX and the drain-section BOX. A highly-doped Si layer, referred to as a non-depletion potential-clamped layer(NPCL), is positioned under and close to the two BOX sections. In the split BOXes and the Si region above the BOXes, the blocking voltage(BV) is divided into two parts by the NPCL. The voltage in the NPCL is clamped to be nearly half of the drain voltage. When the drain voltage approaches a breakdown value, the voltage sustained by the source-section BOX and the Si region under the source are nearly the same as the voltage sustained by the drain-section BOX and the Si region under the drain. The vertical BV is therefore almost doubled. The effectiveness of this new structure was verified for a P-channel SOI lateral double-diffused metal-oxide semiconductor(LDMOS) and can be applied to other high-voltage SOI devices. The simulation results show that the BV in an NPCL P-channel SOI LDMOS is improved by 55% and the specific on-resistance(Ron,sp) is reduced by 69% in comparison to the conventional structure.
基金Supported by the National Natural Science Foundation of China under Grant No 11674123
文摘Developing accurate self-assembly is the key for constructing functional materials from a bottom-up approach.At present, it is mainly hindered by building blocks and driving modes. We design a new self-assembly method based on the magnetic coupling between spin-polarized electrons. First-principles calculations show that spinpolarized electrons from different endohedral metallofullerene(EMF) superatoms can pair each other to ensure a one-dimensional extending morphology. Furthermore, without ligand passivation, the EMF superatoms maintain their electronic structures robustly in self-assembly owing to the core-shell structure and the atomic-like electron arrangement rule. Therefore, it should noted that the magnetic coupling of monomeric electron spin polarization can be an important driving mechanism for high-precision self-assembly. These results represent a new paradigm for self-assembly and offer fresh opportunities for functional material construction at the atomic level.
文摘Different temperatures of water bath was used to extract the intracellular microcystin-LR(MC-LR) of Microcystis aeruginosa. Researching the extraction efficiency under the suitable temperature, so that it could find out the best temperature and time for extracting MC-LR from Microcystis aeruginosa cells. Five equal Microcystis aeruginosa was used to find out the best temperature, extracting at 60℃, 70℃, 80℃, 90℃ and 100℃ for 15 minutes, respectively. Results showed that the content of MC-LR extracted with the water under 100℃ was the highest. But meanwhile, the type and the content of impurities was the highest, too. In addition, another six equal Microcystis aeruginosa was extract with the water under 100℃ for 5min, 10 min, 15 min, 20 min, 25 min and 30 min respectively. It was proved that 20 minutes was enough for extracting MC-LR from Microcystis aeruginosa, no long time was needed.
基金the grant from the Leading Academic Disci-pline Program,National 211 Project of Jinan University (the 3rd phase)the Science and Technology Project of Guangzhou City,No 2008J1-C181-1the Fun-damental Research Funds for the Central Universities,No.21609425
文摘The 4-hydroxy-flavonoid compound luteolin is a phytoestrogen with antioxidant, anti-inflammatory, and anti-tumor properties. The present study analyzed the protective effects of luteolin against rotenone-induced PC12 cell apoptosis in a model of Parkinson's disease (PD). Rotenone (1.6 μmol/L) was utilized to establish the In vitro PD model, resulting in low cell viability and an apoptotic rate of 36.1%. Luteolin (100 μmol/L) pretreatment significantly ameliorated rotenone-induced damage, improved cell morphology and viability, decreased comet tail length, reduced the rate of apoptosis (11.8%), and down-regulated cleaved caspase-3 expression. Results demonstrate that luteolin protects PC12 cells against rotenone-induced apoptosis by decreasing cleaved caspase-3 expression.