排序方式: 共有45条查询结果,搜索用时 15 毫秒
21.
Huyen Tran Thi Thuong Chi Tran Thi Kim Liem Nguyen Quang Hendrik Kosslick 《自然科学进展(英文版)》2019,29(6):641-647
Brookite TiO_2 nanoparticles were synthesized by hydrothermal method and characterized by X-ray powder diffraction(XRD), diffuse reflectance UV–Visible spectroscopy(DRUV), and scanning electron microscopy(SEM). The obtained particles were spherical in shape with the diameter of about ~10 nm under the hydrothermal temperature of 175 °C. The photocatalytic performance of brookite was investigated in the photodegradation of dyes(rhodamine B and rose bengal) under UV-A radiation by low-power lamp. The activity of brookite and the photodegradation efficiency of dyes were estimated using a UV–Visible spectrophotometer and a total organic carbon(TOC) analyzer. Compared to anatase and rutile prepared by the similar synthesis procedure, brookite is highly active in terms of decolourization, aromatic ring opening, and mineralization. 相似文献
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Ethene/norbornene copolymerization by[Me2Si(3—^tertBuCp)(N^tertBu)]TiCl2/MAO—catalyst 总被引:1,自引:0,他引:1
Ethene/norbomene copolymerization by the catalyat system [Me2Si(3-^tertBuCp)(N^tertBu)]TiCl2/MAO was investigated in detail at 30℃,60℃,and 90℃,A mass flow controller was used in this work to ob-tain kinetic data and investigate temperature‘‘‘‘‘‘‘‘s effects on activity, norbomene incorporation,copolymerization parameter,microgtructure,glass transition temperature,and molar masses were described.High copolymer-izstion values rE and high altemation are determined.The number of isotactic altemating sequences is much higher than that of the syndiotactic altemating sequences. 相似文献
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Mira MT Alcaïs A Van Thuc N Thai VH Huong NT Ba NN Verner A Hudson TJ Abel L Schurr E 《Nature genetics》2003,33(3):412-415
Leprosy, a chronic infectious disease caused by Mycobacterium leprae, affects an estimated 700,000 persons each year. Clinically, leprosy can be categorized as paucibacillary or multibacillary disease. These clinical forms develop in persons that are intrinsically susceptible to leprosy per se, that is, leprosy independent of its specific clinical manifestation. We report here on a genome-wide search for loci controlling susceptibility to leprosy per se in a panel of 86 families including 205 siblings affected with leprosy from Southern Vietnam. Using model-free linkage analysis, we found significant evidence for a susceptibility gene on chromosome region 6q25 (maximum likelihood binomial (MLB) lod score 4.31; P = 5 x 10(-6)). We confirmed this by family-based association analysis in an independent panel of 208 Vietnamese leprosy simplex families. Of seven microsatellite markers underlying the linkage peak, alleles of two markers (D6S1035 and D6S305) showed strong evidence for association with leprosy (P = 6.7 x 10(-4) and P = 5.9 x 10(-5), respectively). 相似文献
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Mira MT Alcaïs A Nguyen VT Moraes MO Di Flumeri C Vu HT Mai CP Nguyen TH Nguyen NB Pham XK Sarno EN Alter A Montpetit A Moraes ME Moraes JR Doré C Gallant CJ Lepage P Verner A Van De Vosse E Hudson TJ Abel L Schurr E 《Nature》2004,427(6975):636-640
Leprosy is caused by Mycobacterium leprae and affects about 700,000 individuals each year. It has long been thought that leprosy has a strong genetic component, and recently we mapped a leprosy susceptibility locus to chromosome 6 region q25-q26 (ref. 3). Here we investigate this region further by using a systematic association scan of the chromosomal interval most likely to harbour this leprosy susceptibility locus. In 197 Vietnamese families we found a significant association between leprosy and 17 markers located in a block of approx. 80 kilobases overlapping the 5' regulatory region shared by the Parkinson's disease gene PARK2 and the co-regulated gene PACRG. Possession of as few as two of the 17 risk alleles was highly predictive of leprosy. This was confirmed in a sample of 975 unrelated leprosy cases and controls from Brazil in whom the same alleles were strongly associated with leprosy. Variants in the regulatory region shared by PARK2 and PACRG therefore act as common risk factors for leprosy. 相似文献
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MicroRNA control of Nodal signalling 总被引:1,自引:0,他引:1
Martello G Zacchigna L Inui M Montagner M Adorno M Mamidi A Morsut L Soligo S Tran U Dupont S Cordenonsi M Wessely O Piccolo S 《Nature》2007,449(7159):183-188
MicroRNAs are crucial modulators of gene expression, yet their involvement as effectors of growth factor signalling is largely unknown. Ligands of the transforming growth factor-beta superfamily are essential for development and adult tissue homeostasis. In early Xenopus embryos, signalling by the transforming growth factor-beta ligand Nodal is crucial for the dorsal induction of the Spemann's organizer. Here we report that Xenopus laevis microRNAs miR-15 and miR-16 restrict the size of the organizer by targeting the Nodal type II receptor Acvr2a. Endogenous miR-15 and miR-16 are ventrally enriched as they are negatively regulated by the dorsal Wnt/beta-catenin pathway. These findings exemplify the relevance of microRNAs as regulators of early embryonic patterning acting at the crossroads of fundamental signalling cascades. 相似文献
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Progress in electrical energy storage system: A critical review 总被引:4,自引:0,他引:4
Haisheng Chen Thang Ngoc Cong Wei Yang Chunqing Tan Yongliang Li Yulong Ding 《自然科学进展(英文版)》2009,19(3):291-312
Electrical energy storage technologies for stationary applications are reviewed.Particular attention is paid to pumped hydroelectric storage,compressed air energy storage,battery,flow battery,fuel cell,solar fuel,superconducting magnetic energy storage, flywheel, capacitor/supercapacitor,and thermal energy torage.Comparison is made among these technologies in terms of technical characteris-tics,applications and deployment status. 相似文献
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Many complex networks exist to facilitate the transport of material or information. In this capacity, the authors are often concerned with the continued flow of material or information when a fraction of the links in the complex network is disrupted. In other words, the authors are interested in the robustness of the complex network. In this paper, the authors survey measures of robustness like the average path length, the average clustering coefficient, the global efficiency, the size of largest cluster and use these to analyze the robustness of the bus network in Hanoi, Vietnam. The authors find that the bus network is robust against random failure but sensitive to targeted attack, in agreement with its scale-free character. By examining sharp drops in the average path length within the largest cluster of the Hanoi bus network under successive targeted attack, the authors identify five nodes whose loss lead to the fragmentation of the network into five or six disconnected clusters. These isolated clusters represent geographically the Central, Western, Southern, and Northwestern districts of Hanoi. Special considerations must therefore be given to these five nodes when planners wish to expand the bus network, or make it more robust. 相似文献
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Safe handling of nanotechnology 总被引:7,自引:0,他引:7
Maynard AD Aitken RJ Butz T Colvin V Donaldson K Oberdörster G Philbert MA Ryan J Seaton A Stone V Tinkle SS Tran L Walker NJ Warheit DB 《Nature》2006,444(7117):267-269
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Brennand KJ Simone A Jou J Gelboin-Burkhart C Tran N Sangar S Li Y Mu Y Chen G Yu D McCarthy S Sebat J Gage FH 《Nature》2011,473(7346):221-225
Schizophrenia (SCZD) is a debilitating neurological disorder with a world-wide prevalence of 1%; there is a strong genetic component, with an estimated heritability of 80-85%. Although post-mortem studies have revealed reduced brain volume, cell size, spine density and abnormal neural distribution in the prefrontal cortex and hippocampus of SCZD brain tissue and neuropharmacological studies have implicated dopaminergic, glutamatergic and GABAergic activity in SCZD, the cell types affected in SCZD and the molecular mechanisms underlying the disease state remain unclear. To elucidate the cellular and molecular defects of SCZD, we directly reprogrammed fibroblasts from SCZD patients into human induced pluripotent stem cells (hiPSCs) and subsequently differentiated these disorder-specific hiPSCs into neurons (Supplementary Fig. 1). SCZD hiPSC neurons showed diminished neuronal connectivity in conjunction with decreased neurite number, PSD95-protein levels and glutamate receptor expression. Gene expression profiles of SCZD hiPSC neurons identified altered expression of many components of the cyclic AMP and WNT signalling pathways. Key cellular and molecular elements of the SCZD phenotype were ameliorated following treatment of SCZD hiPSC neurons with the antipsychotic loxapine. To date, hiPSC neuronal pathology has only been demonstrated in diseases characterized by both the loss of function of a single gene product and rapid disease progression in early childhood. We now report hiPSC neuronal phenotypes and gene expression changes associated with SCZD, a complex genetic psychiatric disorder. 相似文献