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287篇 您的检索式:作者名="ZHANG WeiFeng"
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1Generation of iPSCs from mouse fibroblasts with a single gene, Oct4, and small molecules显示文摘由病毒的 transduction 的四抄写因素 Oct4, Klf4, Sox2 和 c-Myc 的介绍能导致体的房间的 reprogramming 进导致的 pluripotent 干细胞(iPSCs ) ,但是 iPSCs 的使用被病毒的交货系统的使用妨碍。导致化学药品的 reprogramming 把一条新奇途径提供给没有任何病毒的基于向量的基因修正,产生 iPSCs。尽管,以前的报告证明几个小分子能代替一些 reprogramming 因素至少二个抄写因素, Oct4 和 Klf4,仍然被要求从老鼠产生 iPSCs 胚胎的成纤维细胞。这里,我们识别特定的化学联合,它是足够的面对一个单个抄写因素从胚胎的老鼠和成年成纤维细胞允许 reprogramming, Oct4 在 20 天以内,代替 Sox2, Klf4 和 c-Myc。用这个处理产生的 iPSCs 类似于胚胎的干细胞以全球基因表示介绍的老鼠,在 vitro 并且在 vivo 的 epigenetic 地位和 pluripotency。我们也发现那 8 天 Oct4 正式就职是足够的面对小分子启用导致 Oct4 的 reprogramming,它建议 reprogramming 在开始的 8 天以内被开始并且独立于连续外长的 Oct4 表示。没有基因修正,这些发现将帮助 iPSCs 的未来产生,以及阐明位于 reprogramming 过程下面的分子的机制。Yanqin Li Qiang Zhang Xiaolei Yin Weifeng Yang Yuanyuan Du Pingping Hou Jian Ge Chun Liu Weiqi Zhang Xu Zhang Yetao Wu Honggang Li Kang Liu Chen Wu Zhihua Song Yang Zhao Yan Shi Hongkui Deng 2011Cell Research2011,21,1:51
2Clinical features and treatment status of hemifacial spasm in China显示文摘Wang Lin Hu Xingyue Dong Hongjuan Wang Wenzhao Huang Yue Jin Lingjing Luo Yumin Zhang Weixi Lian Yajun Liang Zhanhua Shang Huifang Feng Yabo wu Yiwen Chen Jun Luo Weifeng Wan Xinhua 2014Chinese Medical Journal2014,,5:20
3Pluripotent stem cells induced from mouse neural stem cells and small intestinal epithelial cells by small molecule compounds显示文摘最近,我们报导了一条化学途径从老鼠成纤维细胞产生 pluripotent 干细胞。然而,是否化学上导致了 pluripotent 干细胞(CiPSCs ) ,能从要示威的另外的房间类型遗体被导出。用系跟踪,这里,我们首先从成纤维细胞验证 CiPSCs 的产生。下次,我们证明从外胚层的神经干细胞(NSC ) 和从内胚叶的小肠的上皮的房间(IEC ) 能是化学上 reprogrammed 进 pluripotent 干细胞。CiPSCs 源于 NSC 和 IEC 类似于老鼠处于增长率,全球基因表示侧面, epigenetic 地位,自强和区别能力的胚胎的干细胞,和 germline 传播才能。有趣地, pluripotency 基因 Sall4 从不同房间类型,和一样的核心在化学 reprogramming 过程在起始的阶段被表示小分子为 reprogramming 被要求,在从这些多样的房间类型位于化学 reprogramming 下面的分子的机制建议保存。我们的分析也证明这些小分子的使用应该被调整从不同房间类型满足 reprogramming 的要求。一起,这些调查结果证明那条完整的化学 reprogramming 途径能在不同织物起源的房间被使用并且建议化学 reprogramming 是有要延长到更起始的类型的潜力的有希望的策略。Junqing Ye Jian Ge Xu Zhang Lin Cheng Zhengyuan Zhang Shan He Yuping Wang Hua Lin Weifeng Yang Junfang Liu Yang Zhao Hongkui Deng 2016Cell Research2016,26,1:19
4Stable Initialization Scheme for K-Means Clustering显示文摘Though K-means is very popular for general clustering, its performance, which generally converges to numerous local minima, depends highly on initial cluster centers. In this paper a novel initialization scheme to select initial cluster centers for K-means clustering is proposed. This algorithm is based on reverse nearest neighbor (RNN) search which retrieves all points in a given data set whose nearest neighbor is a given query point. The initial cluster centers computed using this methodology are found to be very close to the desired cluster centers for iterative cluster-ing algorithms. This procedure is applicable to clustering algo-rithms for continuous data. The application of the proposed algo-rithm to K-means clustering algorithm is demonstrated. An ex-periment is carried out on several popular datasets and the results show the advantages of the proposed method.XU Junling XU Baowen ZHANG Weifeng ZHANG Wei HOU Jun 2009Wuhan University Journal of Natural Sciences2009,14,1:15
5Spore-pollen-climate factor transfer function and paleoenvironment reconstruction in Dajiuhu,Shennongjia,Central China显示文摘The identified results of 121 surface sediment spore-pollen samples in Shennongjia and meteorological data base of 30 years(January,1971―December,2000)of 7 meteorological stations around Dajiuhu, Shennongjia are used in this study.Selecting 55 species of common spore-pollen with the method of space fitting and stepwise regression we construct the pollen climate factor transfer function of annual mean tem- perature:T=7.649-2.33097X Abies -0.10873X Betula -0.17352X Compositae -0.13176X Cruciferae +0.13356XEuphorbiaceae -0.83069X Campanulaceae +1.96494XPyrrosia+0.38411XPteris+2.77741XSelaginella+0.04439XMonolites.We had reconstructed annual mean temperature series by use of the sporo-pollen samples concentra-tion percentage in peat section with 297 cm thickness in Dajiuhu since 15.753 kaBP.The temperature series reflect well the character of climatic change since the late glacial,which indicates extreme cold climate event of the Oldest Dryas,the Older Dryas,the Younger Dryas and the 8.2 kaBP,the same to the climate fluctuations of Bolling Warm Period and Allerod Warm Period,and the character of temperature change fluctuating frequently at the transition age from the late glacial to the Holocene.The reconstructed temperature also indicate Holocene Optimum,late Holocene warm-dry climate,and the character of climatic change in Dajiuhu in the last 1 ka.The conclusion is that the sporo-pollen samples have important climatic significance to surface sediment and the section of Dajiuhu,Shennongjia and important reference value to studying climatic change during the last glaciation by the temperature transfer function and reconstructed temperature series.ZHU Cheng CHEN Xing ZHANG GuangSheng MA ChunMei ZHU Qing LI ZhongXuan XU WeiFeng 2008Chinese Science Bulletin2008,53,S1:15
6Geochemical characteristics of Cretaceous basaltic rocks in South China and constraints on Pacific plate subduction显示文摘Middle-Late Cretaceous Basaltic rocks (85―110 Ma) are distributed in the contemporaneous downfaulted red basins and volcanic-sedimentary basins in South China (including Hunan, Jiangxi, Guangdong, Fujian, Zhejiang provinces). They are geographically divided into two groups delimited by Wuyishan Range, namely the west area basaltic rocks (WABs) distributing over the west of Wuyishan Range and the east area basaltic rocks (EABs) distributing over the east of Wuyishan Range, and observed having distinct geochemical and isotopic characters. WABs are characterized by relatively low in K2O (0.44%―3.17%), alkalis (K2O+Na2O= 3.27%―6.80%) and Al2O3 (13.08%―16.75%) contents, but high in MgO (5.13%―8.78%) and TiO2 (1.12%―3.35%) contents. WABs are similar to ocean-island basalts (OIB) or intraplate basalts on trace elements and isotopes: no negative Nb and Ta anomalies, relatively low ∑REE (74.66 μg/g―287.72 μg/g) and LaN/YbN (4.49―22.10), low (87Sr/86Sr)i (average ratio is 0.704679), high εNd(t) (?1.81―8.00). In contrast, EABs display relatively high in K2O (0.55%―4.86%), alkalis (K2O+Na2O=2.95%―7.55%) and Al2O3 (15.80%―21.10%) contents, but low in MgO (2.63%―6.28%) and TiO2 (1.19%―1.86%) contents, strong negative Nb and Ta anomalies, enrichment in LILE (K, Rb, Ba and Th), relatively high ΣREE (79.68 μg/g―327.61 μg/g) and LaN/YbN (5.25―26.37), high (87Sr/86Sr)i (average ratio is 0.707658) and negative εNd(t) (?8.50― ?1.22), similar to that of IAB (island arc basalts) or CAB (continental arc basalts). Accordingly, WABs were probably generated under continental rifting tectonic setting related to asthenosphere upwelling, and hence their source was characterized by mixing between EMⅡ with DM. Source of EABs may be enriched lithoshperic mantle which had ever undergone the metasomatism of fluid/melt derived from the subducted Pacific plate.This indicates that subduction of a paleo-Pacific plate (Kula) beneath the Eurasian continent had ever occurred during the late Mesozoic period, but the metasomatism resulted from the subduction was only limited to the east of Wuyishan Range.CHEN Weifeng CHEN Peirong XU Xisheng ZHANG Min 2005Science China Earth Sciences2005,48,12:14
7Natural Variations at TIG1 Encoding a TCP Tran scription Factor Contribute to Plant Architecture Domestication in Rice显示文摘The modification of plant architecture is a crucial target in rice domestication and modern genetic improvement.Although several genes regulating rice plant architecture have been characterized,the molecular mechanisms underlying rice plant architecture domestication remain largely unclear.Here we show that the inclined tiller growth in wild rice is controlled by a single dominant gene,TILLER INCLINED GROWTH 1 (T/Gf),which is located on chromosome 8 and encodes a TCP transcriptional activator.TIG1 is primarily expressed in the adaxial side of the tiller base,promotes cell elongation,and enlarges the tiller angle in wild rice.Variations in the TIG1 promoter of indica cultivars {tig1 allele) resulted in decreased expression of TIG1 in the adaxial side of tiller base and reduced cell length and tiller angle,leading to the transition from inclined tiller growth in wild rice to erect tiller growth during rice domestication.TIG1 positively regulates the expression of EXP A3,EXPB5,and SAUR39 to promote cell elongation and increase the tiller angle.Selective sweep analysis revealed that the tig1 allele was selected in indica cultivars by human beings.The cloning and characterization of TIG1 supports a new scenario of plant architecture evolution in rice.Weifeng Zhang Lubin Tan Hongying Sun Xinhui Zhao Fengxia Liu Hongwei Cai Yongcai Fu Xianyou Sun Ping Gu Zuofeng Zhu Chuanqing Sun 2019Molecular Plant2019,12,8:13
8Drug nanoclusters formed in confined nano-cages of CD-MOF: dramatic enhancement of solubility and bioavailability of azilsartan显示文摘Tremendous efforts have been devoted to the enhancement of drug solubility using nanotechnologies, but few of them are capable to produce drug particles with sizes less than a few nanometers. This challenge has been addressed here by using biocompatible versatile γ-cyclodextrin(γ-CD) metal-organic framework(CD-MOF) large molecular cages in which azilsartan(AZL) was successfully confined producing clusters in the nanometer range. This strategy allowed to improve the bioavailability of AZL in Sprague–Dawley rats by 9.7-fold after loading into CD-MOF. The apparent solubility of AZL/CD-MOF was enhanced by 340-fold when compared to the pure drug. Based on molecular modeling, a dual molecular mechanism of nanoclusterization and complexation of AZL inside the CD-MOF cages was proposed, which was confirmed by small angle X-ray scattering(SAXS) and synchrotron radiation-Fourier transform infrared spectroscopy(SR-FTIR) techniques. In a typical cage-like unit of CD-MOF, three molecules of AZL were included by the γ-CD pairs, whilst other three AZL molecules formed a nanocluster inside the 1.7 nm sized cavity surrounded by six γ-CDs. This research demonstrates a dual molecular mechanism of complexation and nanoclusterization in CD-MOF leading to significant improvement in the bioavailability of insoluble drugs.Yuanzhi He Wei Zhang Tao Guo Guoqing Zhang Wei Qin Liu Zhang Caifen Wang Weifeng Zhu Ming Yang Xiaoxiao Hu Vikramjeet Singh Li Wu Ruxandra Gref Jiwen Zhang 2019Acta Pharmaceutica Sinica B2019,9,1:13
9Propofol differentially induces unconsciousness and respiratory depression through distinct interactions between GABAa receptor and GABAergic neuron in corresponding nuclei显示文摘Propofol is the most commonly used intravenous anesthetic worldwide.It can induce loss of consciousness prior to the occurrence of severe respiratory suppression,which is also a pharmacodynamic feature of all general anesthetics.However,the neural mechanisms underlying this natural phenomenon are controversial and highly related to patient safety.In the present study,we demonstrated that the pharmacodynamic effects of propofol(50 and 100 μM)on suppression of consciousness-related excitatory postsynaptic currents in the medial prefrontal cortex(mPFC)and centromedian nucleus of the thalamus(CMT)were lower than those in the kernel respiratory rhythmogenesis nucleus pre-Botzinger complex(PrBo).Furthermore,we unexpectedly found that the GABAa receptor β3 subunit is the key target for propofol's action and that it is mutually and exclusively expressed in GABAergic neurons.It is also more abundant in the mPFC and CMT,but mainly co-localized with GABAergic neurons in the PrBo.As a result,the differentiated expression pattern should mediate more neuron suppression through the activation of GABAergic neurons in the mPFC and CMT at low doses of propofol(50 μM).However,PrBo GABAergic neurons were only activated by propofol at a high dose(100 μM).These results highlight the detailed pharmacodynamic effects of propofol on consciousness-related and respiration-related nuclei and provide the distinct interaction mechanism between the β3 subunit and GABAergic neurons in mediating the suppression of consciousness compared to the inhibition of respiration.Junli Jiang Yingfu Jiao Po Gao Wen Yin Wei Zhou Yunchun Zhang Yanjun Liu Daxiang Wen Yuan Wang Liang Zhou Tian Yu Weifeng Yu 2021Acta Biochimica et Biophysica Sinica2021,53,8:11
10Probability tree based passenger flow prediction and its application to the Beijing subway system显示文摘Biao LENG Jiabei ZEN Zhang XIONG Weifeng LV Yueliang WAN 2013Frontiers of Computer Science2013,7,2:11
11Antidepressant-Like Action of Single Facial Injection of Botulinum Neurotoxin A is Associated with Augmented 5-HT Levels and BDNF/ERK/CREB Pathways in Mouse Brain显示文摘The present study was designed to examine the therapeutic effects of Botulinum neurotoxin A(BoNT/A)on depression-like behaviors in mice and to explore the potential mechanisms.These results revealed that a single facial injection of BoNT/A induced a rapid and prolonged improvement of depression-like behaviors in naive and space-restriction-stressed(SRS)mice,reflected by a decreased duration of immobility in behavioral despair tests.BoNT/A significantly increased the 5-hydroxytryptamine(5-HT)levels in several brain regions,including the hippocampus and hypothalamus,in SRS mice.BoNT/A increased the expression of the N-methyl-Daspartate receptor subunits NR1 and NR2 B in the hippocampus,which were significantly decreased in SRS mice.Furthermore,BoNT/A significantly increased the expression of brain-derived neurotrophic factor(BDNF)in the hippocampus,hypothalamus,prefrontal cortex,and amygdala,which were decreased in SRS mice.Finally,BoNT/A transiently increased the levels of phosphorylated extracellular signal-regulated kinase(p-ERK)and cAMPresponse element binding protein(p-CREB),which were suppressed in the hippocampus of SRS mice.Collectively,these results demonstrated that BoNT/A treatment has antidepressant-like activity in mice,and this is associated with increased 5-HT levels and the activation of BDNF/ERK/CREB pathways in the hippocampus,supporting further investigation of BoNT/A therapy in depression.Yang Li Jing Liu Xu Liu Cun-Jin Su Qi-Lin Zhang Zhi-Hong Wang Lei-Fang Cao Xue-Yan Guo Ya Huang Weifeng Luo Tong Liu 2019Neuroscience Bulletin2019,35,4:10
12A two-step lineage reprogramming strategy to generate functionally competent human hepatocytes from fibroblasts显示文摘Terminally differentiated cells can be generated by lineage reprogramming,which is,however,hindered by incomplete conversion with residual initial cell identity and partial functionality. Here, we demonstrate a new reprogramming strategy by mimicking the natural regeneration route, which permits generating expandable hepatic progenitor cells and functionally competent human hepatocytes. Fibroblasts were first induced into human hepatic progenitor-like cells (hHPLCs), which could robustly expand in vitro and efficiently engraft in vivo. Moreover, hHPLCs could be efficiently induced into mature human hepatocytes (hiHeps) in vitro, whose molecular identity highly resembles primary human hepatocytes (PHHs). Most importantly, hiHeps could be generated in large quantity and were functionally competent to replace PHHs for drug-metabolism estimation, toxicity prediction and hepatitis B virus infection modeling. Our results highlight the advantages of the progenitor stage for successful lineage reprogramming. This strategy is promising for generating other mature human cell types by lineage reprogramming.Bingqing Xie Da Sun Yuanyuan Du Jun Jia Shicheng Sun Jun Xu Yifang Liu Chengang Xiang Sitong Chen Huangfan Xie Qiming Wang Guangya Li Xuehui LYU Hui Shen Shiyu Li Min Wu Xiaonan Zhang Yue Pu Kuanhui Xiang Weifeng Lai Peng Du Zhenghong Yuan Cheng Li Yan Shi Shichun Lu Hongkui Deng 2019Cell Research2019,29,9:9
13Proanthocyanidins Inhibit Seed Germination by Maintaining a High Level of Abscisic Acid in Arabidopsis thaliana显示文摘Proanthocyanidins (PAs) are the main products of the flavonoid biosynthetic pathway in seeds, but their biological function during seed germination is still unclear. We observed that seed germination is delayed with the increase of exogenous PA concentration in Arabidopsis. A similar inhibitory effect occurred in peeled Brassica napus seeds, which was observed by measuring radicle elongation. Using abscisic acid (ABA), a biosynthetic and metabolic inhibitor, and gene expression analysis by real-time polymerase chain reaction, we found that the inhibitory effect of PAs on seed germination is due to their promotion of ABA via de novo biogenesis, rather than by any inhibition of its degradation. Consistent with the relationship between PA content and ABA accumulation in seeds, PA-deficient mutants maintain a lower level of ABA compared with wild-types during germination. Our data suggest that PA distribution in the seed coat can act as a doorkeeper to seed germination. PA regulation of seed germination is mediated by the ABA signaling pathway.Liguo Jia Qiuyu Wu Nenghui Ye Rui Liu Lu Shi Weifeng Xu Hui Zhi A. N. M. Rubaiyath Bin Rahman Yiji Xia Jianhua Zhang 2012Journal of Integrative Plant Biology2012,54,9:9
14Platelet-rich plasma accelerates skin wound healing by promoting re-epithelialization显示文摘Background:Autologous platelet-rich plasma(PRP)has been suggested to be effective for wound healing.However,evidence for its use in patients with acute and chronic wounds remains insufficient.The aims of this study were to comprehensively examine the effectiveness,synergy and possible mechanism of PRP-mediated improvement of acute skin wound repair.Methods:Full-thickness wounds were made on the back of C57/BL6 mice.PRP or saline solution as a control was administered to the wound area.Wound healing rate,local inflammation,angiogenesis,re-epithelialization and collagen deposition were measured at days 3,5,7 and 14 after skin injury.The biological character of epidermal stem cells(ESCs),which reflect the potential for re-epithelialization,was further evaluated in vitro and in vivo.Results:PRP strongly improved skin wound healing,which was associated with regulation of local inflammation,enhancement of angiogenesis and re-epithelialization.PRP treatment significantly reduced the production of inflammatory cytokines interleukin-17A and interleukin-1β.An increase in the local vessel intensity and enhancement of re-epithelialization were also observed in animals with PRP administration and were associated with enhanced secretion of growth factors such as vascular endothelial growth factor and insulin-like growth factor-1.Moreover,PRP treatment ameliorated the survival and activated the migration and proliferation of primary cultured ESCs,and these effects were accompanied by the differentiation of ESCs into adult cells following the changes of CD49f and keratin 10 and keratin 14.Conclusion:PRP improved skin wound healing by modulating inflammation and increasing angiogenesis and re-epithelialization.However,the underlying regulatory mechanism needs to be investigated in the future.Our data provide a preliminary theoretical foundation for the clinical administration of PRP in wound healing and skin regeneration.Pengcheng Xu Yaguang Wu Lina Zhou Zengjun Yang Xiaorong Zhang Xiaohong Hu Jiacai Yang Mingying Wang Binjie Wang Gaoxing Luo Weifeng He Biao Cheng 2020Burns & Trauma2020,8,1:8
15Strain-tunable electronic and transport properties of MoS2 nanotubes显示文摘Weifeng Li Gang Zhang Meng Guo Yong-Wei Zhang 2014Nano Research2014,7,4:8
16Velvet antler polypeptide is able to induce differentiation of neural stem cells towards neurons in vitro显示文摘OBJECTIVE: To investigate the neural differentiation capacity of water extraction of velvet antler.METHODS: Velvet antler(Cervus Nippon Temminck) polypeptide(VAP) was used to differentiate neural stem cells(NSCs) towards neurons in the study. Firstly, we obtain the polypeptides of VAP by water extraction. Secondly, we observed the morphology, assayed the factors in the media by enzyme-linked immunosorbent assay, and detected the special neural molecules by immuno fl uorescence staining. NSCs were cultured on the cell climbing film. After neuronal differentiation, differentiated NSCs were mounted for immunocytochemistry with immunofluorescence technique.RESULTS: The differentiating cells look like neuron,some special factors, such as Glial cell line-derived neurotrophic factor, nerve growth factor, in the media can be detected while differentiated neuron-like cells can express the special neural molecules.CONCLUSION: Differentiation of NSCs towards neurons can be induced by velvet antler polypeptide.Zhang Lihong Zhuang Zhihong Sun Yanan Ma Shuhua Yang Weifeng Lei Hongtao Zuo Junling Ouyang Jingfeng Wang Yi 2017Journal of Traditional Chinese Medicine2017,37,3:8
17The input/removal rates of size-fractionated ^210Po in the Jiulongjiang estuary and its implications显示文摘The geochemical behaviors of dissolved (<0.4 mm), low molecular weight (<10 kDa) and colloidal (10 kDa- 0.4 mm) 210Po in surface waters from the Jiulongjiang estuary were examined and the input/removal rates of different 210Po species were estimated. Both dissolved and low molecular weight 210Po were considerably removed during estuarine mixing. However, colloidal 210Po was removed only at low salinity regions (S <15) but had input behavior at high salin-ity surface waters (S >15). The input/removal rates of three species indicate that 210Po was removed rapidly in the Jiu-longjiang estuary. The discrepancy of input/removal rates between 210Po species suggests different geochemical be-havior and a dynamic transformation between 210Po species. Low molecular weight 210Po may be more appropriate for characterizing the 210Po behavior in estuary zone than the traditional dissolved 210Po.YANG Weifeng, CHEN Min, HUANG Yipu, QIU Yusheng, ZHANG Lei, XING Na & LI Yanping Department of Oceanography, Xiamen University, Xiamen 361005, China Correspondence should be addressed to Huang Yipu (e-mail: yphuang@ jingxina.xmu.edu.cn) 2003Chinese Science Bulletin2003,48,21:8
18Sorption removal of cephalexin by HNO_3 and H_2O_2 oxidized activated carbons显示文摘Cephalexin's traces within pharmaceutical effluents have toxic impact toward ecological and human health.Low-cost activated carbon derived from Trapa natans husk was oxidized with hydrogen peroxide and nitric acid,and tested for their ability to remove cephalexin from aqueous solutions.Oxidization with H2O2 showed negative effect on the cephalexin sorption,whereas HNO3 oxidization improved the adsorption.The cephalexin adsorption isotherms on the native and HNO3 oxidized carbons correlated well with the Freundlich equation while their kinetics followed the pseudo-second order model.The removal of cephalexin by the native and HNO3 oxidized carbons was found to be most favored at low ionic strength and strong acidic conditions.Based on the thermal and FTIR analyses,the interaction mechanisms of the interaction between cephalexin and the carbons were proposed.Electrostatic attraction,hydrophobic interaction and chemical bonding with surface functional groups were demonstrated as primary mechanisms for cephalexin removal.The nitrogen functionalities on the carbon surface were considered to be an important factor affecting the adsorption process.LIU WeiFeng XIE HuiJun ZHANG Jian ZHANG ChengLu 2012Science China Chemistry2012,55,9:7
19Comparative study on local and global mechanical properties of bobbin tool and conventional friction stir welded 7085-T7452 aluminum thick plate显示文摘7085-T7452 plates with a thickness of 12 mm were welded by conventional single side and bobbin tool friction stir welding(SS-FSW and BB-FSW, respectively) at different welding parameters. The temperature distribution, microstructure evolution and mechanical properties of joints along the thickness direction were investigated, and digital image correlation(DIC) was utilized to evaluate quantitatively the deformation of different zones during tensile tests. The results indicated that heat-affected zone(HAZ), the local softening region, was responsible for the early plastic deformation and also the fracture location for SS-FSW samples, while a rapid fracture was observed in weld nugget zone(WNZ) before yield behavior for all BB-FSW specimens. The ultimate tensile strength(UTS) of SS-FSW joints presented the highest value of 410 MPa, 82% of the base material, at a rotational speed of 300 rpm and welding speed of 60 mm/min,much higher than that of BB-FSW joints, with a joint efficiency of only 47%. This should be attributed to the Lazy S defect produced by a larger extent of heat input during the BB-FSW process. The whole joint exhibited a much higher elongation than the slices. Scanning electron microscopic(SEM) analysis of the fracture morphologies showed that joints failed through ductile fracture for SS-FSW and brittle fracture for BB-FSW.Weifeng Xu Yuxuan Luo Wei Zhang Mingwang Fu 2018Journal of Materials Science & Technology2018,34,1:7
20Effects of ecological factors on secondary metabolites and inorganic elements of Scutellaria baicalensis and analysis of geoherblism显示文摘This study analyzed the effects of ecological factors on secondary metabolites of Scutellaria baicalensis using two sources:92individual roots of S.baicalensis from all over China,and secondary metabolites,medicinal materials and inorganic element contents obtained from the testing of 92 S.baicalensis rhizosphere soil samples.The study used environmental data from the Genuine Medicinal Material Spatial Analysis Database.Most of the chemical constituents of S.baicalensis were negatively correlated to latitude and positively correlated to temperature;generally,the contents of 21 chemical constituents were higher at low latitudes than that at high latitudes.By gradual regression analysis,it was found that the content of baicalin in S.baicalensis was negatively correlated to latitude and generally the content of inorganic elements in soil was excessively high(excluding Mg and Ca),which has a negative effect on the accumulation of chemical constituents in S.baicalensis.Based on the cluster analysis of 21 constituents,S.baicalensis from different places of origin was divided into two groups,and S.baicalensis was not genuine only in a specific small region.Within the zone from Chifeng,Inner Mongolia to Taibai,Shaanxi is suitable for accumulation of secondary metabolites of S.baicalensis and such a zone represents a suitable distribution and potential genuine producing area.GUO LanPing WANG Sheng ZHANG Ji YANG Guang ZHAO ManXi MA WeiFeng ZHANG XiaoBo LI Xuan HAN BangXing CHEN NaiFu HUANG LuQi 2013Science China(Life Sciences)2013,56,11:7
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