塔里木河上游表层沉积物重金属污染特征与潜在生态风险评价

为了解塔里木河上游表层沉积物重金属的污染特征、来源及潜在生态风险,本研究采集并测定塔里木河上游阿拉尔—沙雅段0~10 cm表层沉积物重金属(As、Cd、Cr、Cu、Fe、Mn、Ni、Pb和Zn)的含量,运用主成分分析(PCA)和Pearson相关性分析法进行溯源分析,采用潜在生态危害指数法和地质累积指数法对沉积物中重金属污染状况和潜在生态风险进行评价。结果表明,9种重金属之间均呈显著的正相关关系,塔河上游重金属主要来源于自然沉降,总体污染相对较小;重金属Pb、As和Cd为自然源、农业工业混合源以及交通活动复合源;地质累积指数法评价结果为0级,无污染;潜在生态危害系数法评价结果为各样点的R I均小于150,属于低污染,重金属Cd为中度潜在生态污染,其余重金属均为低度潜在生态污染。

Discussion on the mechanism of Xiaoyao Wan in the treatment of depression and anxiety based on network pharmacology

In order to clarify the targets of Xiaoyao Wan in the treatment of depression and anxiety,the pharmacological database of traditional Chinese medicine system and the analysis platform(TCMSP)were used to search the chemical components and potential targets of Xiaoyao Wan.The databases of Malacards and Genecards were used to mine the targets related to depression and anxiety.With the help of Cytoscape3.2.1 software,the“Xiaoyao Wan-targets-diseases”network is constructed.The PPI network is constructed through String database.Common targets are enriched by cluster Profiler software package in R language.161 active components of Xiaoyao Wan were screened,and 247 targets related to Xiaoyao Wan were predicted(excluding repetitive targets).The related targets of depression and anxiety were 379,337 respectively.Through the intersection of Venny diagram,24 targets of Xiaoyao Wan,depression and anxiety were obtained.24 key targets were screened out by constructing the interaction network of Xiaoyao Wan,depression and anxiety.Pathway enrichment analysis showed that Xiaoyao Wan mainly acts on key targets involves D(2)dopamine receptor(DRD2),Interleukin-6(IL6),5-hydroxytryptamine receptor 2A(HTR2A),Interleukin-1 beta(IL1B),5-hydroxytryptamine receptor 3A(HTR3A),Sodium-dependent dopamine transporter(SLC6A3),D(1A)dopamine receptor(DRD1),Interleukin-10(IL10),Sodium-dependent noradrenaline transporterin(SLC6A2)and other key targets in the treatment of depression and anxiety,and participates in important pathway processes such as Serotonergic synapse,Dopaminergic synapse,Neuroactive ligand-receptor interaction and regulation of neurotransmitter levels.It is speculated that Xiaoyao Wan plays a role in the treatment of depression and anxiety by affecting neurotransmitters 5-HT and DA,participating in hypothalamic-pituitary-adrenal(HPA)and interfering in the process of inflammation.

Response of growth,metabolism and yield of Dendrocalamopsis oldhami to long-day photoperiod and fertilizer compensation

The effects of long-day photoperiod on growth,photo synthetic fluorescence,carbon and nitrogen metabolism,and yield of Dendrocalamopsis oldhami and the compensation effects of fertilization were investigated.A completely randomized design was used with two light factors(bamboo culms cultivated in solar greenhouse under long-day[Ls]and short-day[Ln]treatments);two organic nitrogen fertilizer levels(application of organic fertilizer[OF]and no organic fertilizer[NF]);and three nitrogen fertilizer levels(Low[N0],medium[N1]and high nitrogen[N2]).Leaf chlorophyll and fluorescence parameters(φPo,PIABS,and ETo/CSm)decreased and DIo/CSmincreased in Ls compared to Ln.Indole acetic acid(IAA)and gibberellic acid(GA3)levels decreased,whereas abscisic acid(ABA)increased.Leaf area decreased and leaf dry mass increased.The contents of carbon and nitrogen metabolism-related enzymes(nitrate reductase,glutamine synthetase,amylase,and sucrose synthase)and products(total nitrogen,organic carbon,soluble sugar,and starch)increased.Single bamboo shoot weight and diameter at breast height decreased,whereas shoot quantity and total yield increased.Fertilizer application significantly affected physiological growth and yield in the two light treatments,thus promoting carbon and nitrogen metabolism.TheφPo,PIABS,IAA,and GA3contents increased slightly,whereas ABA levels decreased.Shoot quantity,individual weight,and total yield improved.IA A,soluble sugar,and total yield to organic manure and light were lower than those of nitrogen levels(FN>FL,FO).Other indicators showed lower responses to different fertilization treatments than the light factor(FL>FN,FO).The ability of D.oldhami to alter its morphological and physiobiochemical traits and yield in response to variations in light applications may translate into high phenotypic plasticity.Fertilization significantly improved photoplasticity of D.oldhami.Under Ls,D.oldhami had high metabolic rates.was easily inhibited by light,and showed accelerated leaf senescence,and shoot quantity and total output increased.However,the quality of individual shoots decreased.Different fertilization treatments affected D.oldhami differently under the two light intensities.Ls sensitivity to nitrogen was higher.Fertilization could delay leaf dormancy and senescence under Ls treatment.Organic fertilizer addition could improve yield more effectively,with OFN1being the optimal fertilization level.

Prognostic prediction and expression validation of NSD3 in pan-cancer analyses

Background:Nuclear receptor binding SET domain protein-3(NSD3)is a histone lysine methyltransferase and a crucial regulator of carcinogenesis in several cancers.We aimed to investigate the prognostic value and potential function of NSD3 in 33 types of human cancer.Methods:The data were obtained from The Cancer Genome Atlas.Kaplan-Meier analysis,CIBERSORT,gene set enrichment analysis,and gene set variation analysis were performed.The expression of NSD3 was measured using quantitative real-time polymerase chain reaction and western blot.Results:The expression of NSD3 was altered in pan-cancer samples.Patients with higher levels of NDS3 generally had shorter overall survival and disease-specific survival.Levels of NSD3 were positively correlated with DNA copy number variation(CNV)in pan-cancer.NSD3 expression was also associated with tumor mutation burden and microsatellite instability.The levels of immune-cell infiltration differed significantly between high and low NSD3 expression.NSD3 negatively correlated with levels of CD8+T cells.Functional enrichment analysis showed that while NSD3 expression was positively associated with several immune cell-related and histone methylation-related pathways,it was negatively correlated with cell metabolism-related,drug transport-related,and drug metabolismrelated pathways.NSD3 levels in the cell lines tested were significantly different.In U251 and NCI-H23 cells,silencing NSD3 inhibited cell proliferation and promoted apoptosis.Conclusions:NSD3 expression was changed in pan-cancer samples that was also verified in cell lines.NSD3 was associated with CNV and immune-cell infiltration.A poor prognosis was predicted in patients with high expression of NSD3.NSD3 might hence be a potential marker for predicting tumor prognosis.

Allelic functional variation of FimH among Salmonella enterica subspecies

Salmonella enterica has a wide diversity,with numerous serovars belonging to six different subspecies with dynamic animal-host tropism.The FimH protein is the adhesin mediating binding to various cells,and slight amino acid discrepancy significantly affects the adherence capacities.To date,the general function of FimH variability across dif-ferent subspecies of Salmonella enterica has not been addressed.To investigate the biological functions of FimH among the six Salmonella enterica subspecies,the present study performed several assays to determine biofilm for-mation,Caenorhabditis elegans killing,and intestinal porcine enterocyte cell IPEC-J2 adhesion by using various FimH allele mutants.In general,allelic mutations in both the lectin and pilin domains of FimH could cause changes in bind-ing affnity,such as the N79S mutation.We also observed that the N79S variation in Salmonella Dublin increased the adhesive ability of IPEC-J2 cells.Moreover,a new amino acid substitution,T260M,within the pilin domain in one subspecies llb strain beneficial to binding to cells was highlighted in this study,even though the biofilm-forming and Caenorhabditis elegans-killing abilities exhibited no significant differences in variants.Combined with point muta-tions being a natural tendency due to positive selection in harsh environments,we speculate that allelic variation T26oM probably contributes to pathoadaptive evolution in Salmonella enterica subspecies llb.

不同供钾水平下烤烟生长及硝态氮吸收动力学特征

采用盆栽砂培试验方法研究了不同钾水平供应下烤烟生长及其对吸收硝态氮的动力学参数特征的影响。主要结论如下:与低钾(K1)、高钾(K3)处理相比,烤烟在中钾(K2)处理时地上部、根系鲜、干重均增加;随钾浓度增加,钾由根系向地上部运输比例增加,而烤烟生育前期净光合速率无显著性差异,但后期净光合速率显著增加;中钾(K2)水平增加根系总根长、总表面积、平均直径和总体积,而高钾(K3)水平反而有抑制作用。不同供钾水平预处理后,烤烟对NO3^--N吸收符合离子吸收动力学模型,其吸收动力学参数表现为钾水平预处理浓度增加后,Vmax增大,Km值增加,但增加的幅度不一致。与低钾(K1)预处理相比,高钾(K3)预处理降低烤烟根系高亲和力系统对NO3^--N的吸收速率,而中钾(K2)处理提高烤烟根系高亲和力系统的NO3^--N的吸收速率,表明烤烟根系吸收NO3?-N的高亲和力系统受钾水平调控,适宜钾浓度预处理提高烤烟根系对低浓度NO3?-N的吸收。对低亲和系统来说,与低钾预处理相比,中钾(K2)和高钾(K3)预处理均提高了烤烟根系低亲和力系统对NO3?-N吸收,表明长期高钾环境生长下的烤烟,根系对硝态氮吸收的低亲和力系统影响较小,而长期低钾环境生长下的烤烟,根系对硝态氮吸收低亲和力系统有抑制作用。

中西药联合治疗特发性少弱畸精子症的有效性和安全性

目的:探讨复方玄驹胶囊联合左卡尼汀口服液治疗特发性少弱畸精子症的疗效与安全性。方法:本研究共纳入2017年10月1日至2018年9月30日佛山市妇幼保健院收治的诊断为特发性少弱畸精子症患者154例,并随机分为观察组与对照组各77例,观察组口服左卡尼汀口服液10 mL·次^-1,2次·d^-1,及复方玄驹胶囊3.78 g·次^-1,3次·d^-1,对照组服用安慰剂维生素B1为10 mg·次^-1,3次·d^-1。两组患者均规律治疗3个月。比较治疗前后观察组和对照组精液常规参数的变化以及自然妊娠结局,同时观察有无不良反应的发生。结果:治疗3个月后观察组精液质量指标包括精子浓度、前向运动精子百分率(PR)、正常精子形态率均显著高于治疗前,差异具有统计学意义(P <0.05),并且高于对照组治疗后,差异具有统计学意义(P <0.01);观察组服药期间女性配偶临床妊娠率高于对照组,组间比较,差异具有统计学意义(P <0.05)。两组患者服药后均无头痛、呕吐、过敏等严重不良反应发生。结论:复方玄驹胶囊结合左卡尼汀口服液治疗特发性少弱畸精子症疗效好,安全性高,可显著提高精子浓度、前向运动精子百分率及正常形态精子的比例,并提高患者女性配偶的自然妊娠率。

Analysis on Change Trend and Influencing Factors of Natural Resource Utilization of Community Farmers around the Habitat of Giant Pandas

The habitat of giant pandas borders the living areas of farmers in surrounding communities. Due to the low level of economic development and resource used method, the life of community farmers depends on the natural resources of the habitat of giant pandas. Analyzing the natural resource utilization of farmers in communities around the habitat of giant pandas is conducive to formulating more reasonable management policies and protecting the habitat of giant pandas more effectively. Based on the field survey data, this paper classifies the main ways of community farmers using the natural resources of the habitat of giant pandas, counts the quantity of resources used and analyzes their change trends. On this basis, this paper selects indicators, constructs a model and analyzes the main influencing factors affecting the natural resources utilization of community farmers from three aspects: the individual characteristics of household heads, the family characteristics of community farmers and the residence characteristics of community farmers.

血小板/淋巴细胞比值升高预示中国终末期肾病患者罹患MPO-ANCA相关性血管炎风险降低

目的:血小板/淋巴细胞比值(platelet-to-lymphocyte ratio,PLR)作为一种新型炎症指标,在系统性红斑狼疮和IgA血管炎等炎症疾病中得到了研究。PLR是否可作为评估抗中性粒细胞胞浆抗体(anti-neutrophil cytoplasmic antibody,ANCA)相关性血管炎患者疾病活动的生物标志物目前研究较少。本研究旨在探讨中国髓过氧化物酶-抗中性粒细胞胞浆抗体(myeloperoxidase-anti-neutrophil cytoplasmic antibody,MPO-ANCA)相关性血管炎患者诊断时的PLR与炎症反应及疾病活动度的关系,评估PLR是否能预测终末期肾病(end stage of renal disease,ESRD)的进展和全因死亡率。方法:收集MPO-ANCA相关性血管炎患者的临床、实验室、病理特征及预后资料。采用Spearman相关分析检验两个连续变量之间的关联。采用Cox回归分析PLR与ESRD或全因死亡率之间的相关性。结果:连续纳入190名MPO-ANCA相关性血管炎患者。基线PLR与CRP(r=0.333,P<0.001)和ESR(r=0.218,P=0.003)呈正相关。PLR与伯明翰血管炎活动度评分(Birmingham Vasculitis Activity Score,BVAS)无明显相关性。PLR≥330的患者比PLR<330的患者表现出更好的累积肾脏生存率(P=0.017)。然而,PLR≥330的患者和PLR<330的患者在诊断时的累积患者生存率方面差异无统计学意义(P>0.05)。多因素分析结果显示PLR与ESRD风险降低相关(HR=0.518,95%CI:0.278~0.963,P=0.038),没有发现PLR与全因死亡率之间有相关性(HR=1.081,95%CI:0.591~1.976,P=0.801)。结论:PLR与CRP和ESR呈正相关。PLR可以独立预测ESRD的风险。

经颅磁刺激治疗后孤独症谱系障碍儿童表情识别过程神经活动的变化

目的:探讨低频重复经颅磁刺激(rTMS)对孤独症谱系障碍(ASD)儿童表情识别过程中前额叶皮质(PFC)氧合血红蛋白(HbO)浓度的影响。方法:选取15例符合美国精神障碍诊断与统计手册第4版(DSM-IV)诊断标准的汉族ASD儿童15例,平均年龄为(73±25)月。用fNIRS检测进行表情识别任务时PFC的HbO浓度,经12周rTMS治疗后复测fNIRS;rTMS刺激部位包括左侧Broca区、左侧额前、左枕叶,频率为1Hz。结果:治疗后,ASD儿童识别高兴表情时,左背外侧PFC的HbO水平下降(P<0.05),右背外侧PFC的HbO水平升高(P<0.05);识别悲伤表情时,各通道HbO水平变化无统计学意义(均P>0.05);识别中性表情时,左腹外侧PFC(P<0.05)、左后侧PFC(P<0.01)HbO水平下降,左背外侧PFC、右眶额叶HbO水平升高(均P<0.05)。结论:低频rTMS可能影响ASD儿童表情识别过程神经功能活动。

269例抗中性粒细胞胞浆抗体相关性血管炎患者的临床病理特征及预后

目的:了解抗中性粒细胞胞浆抗体(antineutrophil cytoplasimc antibody,ANCA)相关性血管炎(ANCAassociated vasculitis,AAV)的临床病理特征、预后及其影响因素。方法:回顾性分析中南大学湘雅医院2010年1月至2018年1月新诊断为AAV的269例住院患者的基本资料、临床病理数据,定期随访肾存活及患者存活情况,并对其临床病理及预后数据进行统计学分析及预后因素分析。结果:在269例AAV患者中,显微镜下多血管炎(microscopic polyangiitis,MPA)225例,占83.64%;肉芽肿性多血管炎(granulomatosis with polyangiitis,GPA)33例,占12.27%;嗜酸性肉芽肿性多血管炎(eosinophilic granulomatosis with polyangiitis,EGPA)11例,占4.09%。在MPA患者中,男女比例约为1:1,而GPA和EGPA患者中男性明显多于女性。从发病到确诊的中位时间为64.0 d,30 d内确诊65例,占24.16%。94.67%的MPA患者肾受累,显著高于GPA患者(63.63%),GPA累及耳鼻喉系统更常见(42.42%)。肾1年生存率在GPA和MPA患者中分别为75%和59.3%,1年病死率分别为16.7%和16.9%。多因素logistic回归分析显示:低血小板、低球蛋白血症、低免疫球蛋白G及血清肌酐升高是AAV患者1年肾生存率的危险因素,而血清肌酐升高是AAV患者全因死亡的独立危险因素。结论:AAV患者以MPA为主,患者进展为终末期肾病比例和病死率仍较高。早期诊断和及时治疗对改善AAV患者预后至关重要。

IgA肾病小鼠模型的改良

目的建立新型IgA肾病小鼠模型,为研究IgA肾病的科研工作提供新的造模方法。方法选取BALB/c小鼠40只,分为对照组(n=20)和模型组(n=20),模型组给予牛血清白蛋白灌胃,四氯化碳皮下注射联合腹腔注射,尾静脉注射脂多糖,对照组给予相应剂量的生理盐水。定期收集24 h尿液,检测尿蛋白和尿红细胞,实验结束时摘眼球取血,留取肾脏和肝脏行组织病理学检查。结果模型组小鼠出现不同程度的血尿和蛋白尿,光镜下可见肾脏轻度系膜细胞及系膜基质增生,免疫荧光显示肾小球系膜区有IgA免疫荧光物质沉积,电镜下可见系膜细胞、系膜基质轻度增生,有电子致密物沉积,足突阶段性融合,符合IgA肾病的肾脏病理改变;对照组小鼠各项指标均正常。结论改良型IgA肾病小鼠模型临床表现和病理改变与人类IgA肾病相似,且造模时间相对较短,操作方法简单易行,成功率高,是一种较为理想的研究IgA肾病的动物模型。

π-π作用下的VOPc/g-C_3N_4用于有效提升可见光光催化制氢性能（英文）

近年来,随着全球科学技术的进步和工业的不断发展,人们的经济生活水平有了极大的提高,但同时也造成能源短缺和环境污染问题,成为21世纪制约经济和社会进一步发展的严重瓶颈,因此开发和研究环保和可再生的绿色能源技术是一项紧迫任务.自首次报道用二氧化钛为电极、采用光电化学分解水制氢之后,光催化分解水制氢引起了人们极大的兴趣,并被认为是缓解全球能源问题的最有希望的解决方案之一.其中,实现有效的太阳能制氢生产中最关键因素是设计稳定、高效和经济的光催化剂,并且能够利用可见光区进行工作(入射到地球上46%的太阳光谱是可见光).聚合物石墨相氮化物(g-C_3N_4)作为一种对可见光响应的新型无机非金属半导体光催化剂,被认为是一种"可持续"有机半导体材料,目前已并被广泛应用于各种光催化反应中.但是由于其光生电子-空穴在动力学上具有相对较大的复合速率,单纯g-C_3N_4的光催化活性远远达不到人们的要求.因此,应该尽可能的提高电荷转移动力学来抑制g-C_3N_4中光生电荷的复合,从而提高光生电荷从g-C_3N_4转移至反应位点的迁移速率.在前期研究的基础上,本文利用钒氧酞菁(VOPc)分子通过p-p相互作用以修饰g-C_3N_4的表面和电子结构,从而提高其光生电子-空穴的分离效率,最终极大提升其可见光光催化制氢性能.本文采用紫外可见光谱(UV-vis),高分辨透射电镜(HRTEM),傅里叶变换红外光谱(FT-IR), X-射线能谱(XPS),稳态光致发光光谱(PL),时间分辨光致发光光谱(TRPL),光电流和阻抗等一系列表征手段研究了VOPc/g-C_3N_4(VOPc/CN)复合催化剂的结构和性质.FT-IR, XPS及mapping等结果表明, VOPc分子已经成功引入到g-C_3N_4表面且未对其晶相、电子结构及其纳米片结构产生显著影响;UV-vis结果显示, VOPc分子成功引入并通过非共价键的p-p作用连接.总之,引入VOPc分子即拓展了催化剂对可见光的响应区域,又有利于光生载流子的传递和光生电子-空穴对的有效分离.当引入4wt%的VOPc分子时, VOPc/CN复合光催化剂的产氢速率增加至65.52μmolh-1, 420 nm处的量子效率高达6.29%,是单纯g-C_3N_4的6倍.此外,该催化剂在可见光下连续照射反应20 h后,其光催化活性几乎没有降低,表现出良好的光化学稳定性.由于两者LUMO和HOMO轨道之间的良好匹配,在光催化过程中光生电子-空穴在VOPc和g-C_3N_4之间实现了空间分离,有效阻止了光生电子-空穴对的复合,因而g-C_3N_4光催化制氢性能显著提升.同时对比了利用NiS和Ni Px做助剂的g-C_3N_4的可见光光催化制氢性能.结果显示, VOPc/CN复合光催化剂具有较好的光催化性能.总之,本文通过一种简单、经济、有效的方法将两种新兴的功能材料有机地复合在一起,用于可见光照射下高效光催化制氢,为以后合理地开发用于太阳能转换的更为高效经济的材料提供了一个新的思路.

艾灸治疗强直性脊柱炎的分子作用机制研究进展

艾灸作为中医护理技术的重要组成部分,在改善强直性脊柱炎(ankylosing spondylitis,AS)症状方面作用独特,艾灸干预AS的机制研究主要集中在抗炎、免疫调节、骨代谢调节、肠道菌群调节等方面。分子医学对进一步阐明艾灸干预AS的机制具有重要意义。但艾灸干预AS的分子机制研究仍存在一些问题:现有的生物医学研究方法仅从某一特定单一领域进行探索,缺乏基于生物医学网络的艾灸靶向分子的探索,今后可借助组学技术、构建组学间生物信息交互网络,整体、系统地探讨艾灸对AS的分子网络作用;艾灸对上游成骨转录因子及相关信号通路WNT、β-catenin和BMP/Smads等的影响尚未明确,今后的研究可着眼于骨重建的相关信号靶点,阐明艾灸抗新骨形成的机制;此外,缺乏从代谢物的角度阐明艾灸治疗AS的分子机制研究,需进一步借助代谢组学技术,更加系统地探索艾灸治疗AS的机制。

自锚式双塔悬索桥在近场与远场地震作用的动力响应

为探究近场、远场、脉冲和非脉冲四种地震作用下自锚式双塔悬索桥的地震响应,首先基于sap2000建立某自锚式双塔悬索桥三维空间有限元模型,其次依据该桥场地条件从PEER中选取近场、远场、脉冲和非脉冲地震动,最后将该四种地震动作为有限元模型的激励源,以此探究自锚式双塔悬索桥的地震响应。研究表明:近场脉冲地震动产生的位移响应最大,约为0.53m;四种地震作用下吊杆和主缆轴力变化规律保持一致,边跨的端吊杆轴力有最大值,最大值约为9800kN,而靠近桥塔处的吊杆轴力有较小值,仅约为500kN。主缆轴力在靠近桥塔处达到最大值,在跨中和边跨处有较小值;四种地震作用下桥塔塔底内力和支座反力均呈现对称关系,但不完全相等。主梁弯矩图在塔梁连接处主梁存在较大负弯矩,主梁剪力在塔梁处存在突变效应。

Enhanced Poly(ethylene terephthalate)Hydrolase Activity by Protein Engineering

Poly(ethylene terephthalate)hydrolase(PETase)from Ideonella sakaiensis exhibits a strong ability to degrade poly(ethylene terephthalate)(PET)at room temperature,and is thus regarded as a potential tool to solve the issue of polyester plastic pollution.Therefore,we explored the interaction between PETase and the substrate(a dimer of the PET monomer ethylene terephthalate,2PET),using a model of PETase and its substrate.In this study,we focused on six key residues around the substrate-binding groove in order to create novel high-efficiency PETase mutants through protein engineering.These PETase mutants were designed and tested.The enzymatic activities of the R61A,L88F,and I179F mutants,which were obtained with a rapid cell-free screening system,exhibited 1.4 fold,2.1 fold,and 2.5 fold increases,respectively,in comparison with wild-type PETase.The I179F mutant showed the highest activity,with the degradation rate of a PET film reaching 22.5 mg perμmol·L^-1 PETase per day.Thus,this study has created enhanced artificial PETase enzymes through the rational protein engineering of key hydrophobic sites,and has further illustrated the potential of biodegradable plastics.

Physical properties and catalog of EW-type eclipsing binaries observed byLAMOST

EW-type eclipsing binaries(hereafter called EWs)are strong interacting systems in which both component stars usually fill their critical Roche lobes and share a common envelope.Numerous EWs were discovered by several deep photometric surveys and there were about 40 785 EW-type binary systems listed in the international variable star index(VSX)by 2017 March 13.7938 of them were observed with LAMOST by 2016 November 30 and their spectral types were identified.Stellar atmospheric parameters of 5363 EW-type binary stars were determined based on good spectroscopic observations.In the paper,those EWs are cataloged and their properties are analyzed.The distributions of orbital period(P),effective temperature(T),gravitational acceleration(log(g)),metallicity([Fe/H])and radial velocity(RV)are presented for these observed EW-type systems.It is shown that about 80.6% of sample stars have metallicity below zero,indicating that EW-type systems are old stellar populations.This is in agreement with the conclusion that EW binaries are formed from moderately close binaries through angular momentum loss via magnetic braking that takes a few hundred million to a few billion years.The unusually high metallicities of a few percent of EWs may be caused by contamination of material from the evolution of unseen neutron stars or black holes in the systems.The correlations between orbital period and effective temperature,gravitational acceleration and metallicity are presented and their scatters are mainly caused by(i)the presence of third bodies and(ii)sometimes wrongly determined periods.It is shown that some EWs contain evolved component stars and the physical properties of EWs mainly depend on their orbital periods.It is found that extremely short-period EWs may be older than their long-period cousins because they have lower metallicities.This reveals that they have a longer timescale of pre-contact evolution and their formation and evolution are mainly driven by angular momentum loss via magnetic braking.

The effect of extrusion conditions on the properties and textures of AZ31B alloy

The effect of extrusion conditions on the tensile properties and texture of AZ31B alloy has been investigated by means of optical microscopy(OM),scanning electron microscopy(SEM),electron backscattered diffraction(EBSD)and tensile tests.It is found that the ultimate tensile strength(UTS),the yield strength(YS)and elongation(EN)of the extruded AZ31B alloy are more significantly influenced by extrusion velocities in contrast with temperature.Although the extrusion conditions are different,the {1102}<0101> texture is the chief texture in the AZ31B after extrusion.Moreover,the extrusion textures become scattered with increasing the temperatures at the same extrusion velocity.As the extrusion velocity is raised at the same temperature,the orientation density of textures increases and the separated textures become relatively concentrated.This leads to the changes of tensile properties at different extrusion conditions.©2017 Production and hosting by Elsevier B.V.on behalf of Chongqing University.

TiO_2纳米棒阵列的制备及形貌控制

利用简单的水热法在FTO基底上制备了TiO_2纳米棒阵列,研究了水热反应温度、钛酸丁酯加入量、水热反应时间、盐酸浓度等因素对TiO_2纳米棒阵列形貌的影响。结果表明,随着水热反应温度在150～180℃之内升高,纳米棒的径向生长加快,纳米棒阵列的面密度和空隙减小;随着钛酸丁酯的用量增大,水热溶液中晶核形成速度加快,促进了TiO_2纳米棒的径向和轴向生长,但TiO_2纳米棒阵列的面密度基本保持不变,纳米棒之间的空隙减小;随着水热反应时间的增加,TiO_2纳米棒主要沿着轴向生长,径向宽度基本保持不变;随着盐酸浓度的增大,TiO_2纳米棒阵列的面密度逐渐减小,纳米棒之间的空隙不断增大。

Recent advances in wave energy converters based on nonlinear stiffness mechanisms

Wave energy is one of the most abundant renewable clean energy sources,and has been widely studied because of its advantages of continuity and low seasonal variation.However,its low capture efficiency and narrow capture frequency bandwidth are still technical bottlenecks that restrict the commercial application of wave energy converters(WECs).In recent years,using a nonlinear stiffness mechanism(NSM)for passive control has provided a new way to solve these technical bottlenecks.This literature review focuses on the research performed on the use of nonlinear mechanisms in wave energy device utilization,including the conceptual design of a mechanism,hydrodynamic models,dynamic characteristics,response mechanisms,and some examples of experimental verification.Finally,future research directions are discussed and recommended.