969 resultados para explosive precursors


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The complexes of alpha,beta-K(a)H(b)XW(9)O(37)(InH2O)(3) . xH(2)O (X = Si, Ge; a+b = 7) were synthesized from their lacunary precursors alpha,beta-XW(9)O(34)(10-) (X = Si, Ge) and characterized by elemental analysis, W-183 NMR, IR and UV spectroscopy and polarography. W-183 NMR spectra of the title complexes consist of two lines with intensity ratio 2:1, as expected for the C-3 nu structure of trisubstituted A alpha- and A beta-Keggin anions.

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In order to raise the room temperature ionic conductivity and improve the mechanical strength of a PEO-based polymer electrolyte, a non-crystalline two-component epoxy network was synthesized by curing diglycidyl ether of polyethylene glycol (DGEPEG) with triglycidyl ether of glycerol (TGEG) in the presence of LiClO4 salt, which acts in this system as both a ring opening catalyst and a source of ionic carrier. The structure of the precursors, the curing process and the cured films have been characterized by C-13 NMR, IR, DSC and ionic conductivity measurement techniques. The electrolyte system exhibits an ionic conductivity as high as similar to 10(-5) S/cm at 25 degrees C and is mechanically self-supportable. The dependence of ionic conductivity was investigated as a function of temperature, salt content, MW of PEG segment in DGEPEG and the proportion of DGEPEG in DGEPEG/TGEG ratio.

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[Si(W2O7)(6)](8-) pillared LDH structure hydroxides were synthesized by the method of restructuring of the thermally decomposed hydrotalcite-like compounds for Zn-Al and Mg-Al oxide systems. [P(W2O7)(6)](8-) pillared Ni-Al LDH structure hydroxide was synt

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An epoxy network-LiClO4 electrolyte system was prepared from diglycidyl ether of polyethylene glycol and triglycidyl ether of glycerol, cured in the presence of LiClO4 only. Various techniques were used to characterize the chemical structure of the precursors and the correlation between the viscoelasticity and conductivity of the cured films was examined.

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The reaction of LnCl3.2LiCl with 1 equiv of MeCpNa in THF gives the complexes [(THF)2Li(mu-Cl)2]2[MeCpLn(THF)] (Ln = Nd (1), La (2)) in good yield. These precursors react further with 2 equiv of LiNPh2 to produce the new complexes [Li(DME)3][MeCpLn(NPh2)3] (Ln = La (3), Pr (4), Nd (5)). They have been characterized by elemental analyses and IR and NMR spectra, as well as by structural analyses of 1 and 3. The chloride 1 crystallizes in the monoclinic space group P2(1)/n (No. 14) with a = 12.130 (5) angstrom, b = 17.343 (5) angstrom, c = 17.016 (5) angstrom, beta = 108.54 (3)-degrees, V = 3393.87 angstrom3, Z = 4, and D(c) = 1.45 g/cm3. Least-squares refinement led to a final R value of 0.051 (I greater-than-or-equal-to 3-sigma(I(o))) for 2004 independent reflections. Complex 3 crystallizes in the monoclinic space group P2(1)/c (No. 14) with a = 18.335 (6) angstrom, b = 16.576 (5) angstrom, c = 17.461 (6) angstrom, beta = 96.04 (3)-degrees, V = 5277.17 angstrom3, D(c) = 1.26 g/cm3, Z = 4, and R = 0.057 (I greater-than-or-equal-to 2.5-sigma(I(o))) for 3378 reflections. The structure of 3 consists of discrete ion pairs [Li(DME)3]+ and [MeCpLa(NPh2)3]- with average La-N and La-C(ring) distances of 2.459 (8) and 2.84 (1) angstrom, respectively.

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Three pairs of polyimide/polyimide blends (50/50 wt%) with different molecular structures were prepared by two ways, i.e. mixing of the polyamic acid precursors with subsequent imidization, and direct solution mixing of the polyimides. The blends were studied with DMA technique. The results obtained show that all the blends prepared with these two different ways are miscible, as there existed only one glass transition temperature(Tg) for all the blends. It is suggested that the miscibility of these polyimide/polyimide blends is a result of the strong inter-molecular charge-transfer interaction between the chains of their components.

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Currently, antioxidants are added in the human diet to prevent free radical-induced cell damage, and there has been an explosive interest in the use of antioxidant nutritional supplements. The effects of different factors on the antioxidant activity of phycocyanins (PCs) were studied. The results showed that PCs generated hydroxyl radicals in the light, while scavenging them in the dark. When PCs were denatured by sodium dodecyl sulfate, urea and in alkaline condition, their ability to generate hydroxyl radicals disappeared and that of scavenging them greatly increased. This showed that the phycobilin moiety is the main part of PC involved in scavenging hydroxyl radicals. Trypsin hydrolysis of PCs showed that the apoprotein portion of the molecule also made a significant contribution to the antioxidant activity.

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The pacifastin family, characterized by several conserved arrays of six cysteine residues, is a newly identified serine protease inhibitor (SPI) family discovered uniquely in arthropods and plays important roles in multiple biological processes. In the present study, the full-length cDNA of a pacifastin light chain (designated ESPLC) was cloned from the Chinese mitten crab Eriocheir sinensis by expressed sequence tags (ESTs) and PCR techniques. The 1036 bp ESPLC cDNA contained an 831 bp open reading frame (ORF) encoding a putative pacifastin-related peptide of 276 amino acids, a 5'-untranslated region (UTR) of 67 bp, and a 3'-UTR of 138 bp. Six putative conserved domains sharing a characteristic cysteine array (Cys-Xaa(9-12)-Cys-Asn-Xaa-Cys-Xaa-Cys-Xaa(2-3)-Gly-Xaa(3-4)-Cys-Thr-Xaa(3)-Cys) were identified in the deduced amino acid sequence of ESPLC. The conservation of these PLDs (pacifastin light chain domains) and the relative higher similarity of ESPLC to other pacifastin-related precursors suggested that ESPLC was a member of pacifastin family. The mRNA transcripts of ESPLC were found to be higher expressed in hepatopancreas, gill and haemolymph than in gonad, muscle and heart, with the highest expression level in hepatopancreas. The ESPLC mRNA expression in haemolymph of Chinese mitten crab was up-regulated at 2 h and 12 h after challenged with Listonella anguillarum. The tissue distribution and temporal characteristics of ESPLC mRNA expression, similar to that of prophenoloxidase gene in E. sinensis, suggested that ESPLC was potentially involved in the response against invading bacteria, with the possibility that it functioned in the prophenoloxidase system in E sinensis. (C) 2008 Elsevier Ltd. All rights reserved.

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Myf-5, a member of the myogenic regulatory factors (MRF), has been shown to be expressed in muscle precursors in early stage zebrafish embryos. The MRFs, including MyoD, Myf-5, Myogenin and MR-F4, belong to the basic Helix-Loop-Helix transcription factors that contain a conserved basic Helix-Loop-Helix (bHLH) domain. To better understand the role of Myf-5 in the development of fish muscles, we have isolated the Myf-5 genomic sequence and cDNA from Flounder (Paralichthys olivaceus), and analyzed its structures and patterns of expression. Promoter analysis identified several putative transcription factor binding sites such as an E-box, NF-Y sites that might confer muscle-specific expression. Myf-5 transcripts were first detected in the paraxial mesoderm that gives rise to slow muscles. During somitogenesis, Myf-5 expression was found in developing somites. Myf-5 expression decreased gradually in somites in the anterior region, but remained strong in the newly formed somites. In the hatching stage, the expression was also detected in other muscle cells such as head muscle and fin muscle. In the growing fish, RT-PCR results showed that Myf-5 was expressed in the skeletal muscle and intestine. (c) 2006 Elsevier Inc. All rights reserved.

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胸苷酸合成酶(thymidylate synthase,简称TS)和二氢叶酸还原酶(dihydrofolate reductase, 简称DHFR)都是叶酸依赖性酶,在维持DNA合成和DNA修复上发挥关键作用,并且多年来一直是肿瘤研究和化疗的重要靶点。我们前期的研究发现,TS和DHFR在翻译水平上存在负反馈调控机制。人TS和DHFR可以与其自身的mRNA结合,从而抑制mRNA的表达,化疗药物可以与TS或者DHFR相互作用,形成的复合物不能与TS mRNA结合, 使负反馈机制丧失。因此深入研究TS和DHFR的翻译调控机理,对阐明肿瘤抗药性机制,对发现新的抗肿瘤药物和肿瘤的治疗都具有十分重要的意义。 本论文利用mRNA体外展示技术,构建多肽库(约10万亿种多肽分子),利用多种实验手段将mRNA体外展示技术进行优化,提高了多肽库融合肽的产量,提高了mRNA体外展示技术筛选的特异性。将TS mRNA分子上的顺式因子TS30 RNA固定于磁珠上,将融合肽库与顺式因子作用,经过6轮循环,由多肽库中获得了与TS mRNA高度亲和的多肽序列,体外结合实验证明亲和肽可以与TS全长mRNA结合,体外翻译实验证明多肽可以抑制TS mRNA的翻译。并且利用phage display技术由噬菌体肽库(12个氨基酸随机肽库)经过四轮筛选,分别筛选到TS和DHFR的亲和肽,凝胶阻滞实验证明它们分别能与TS和DHFR mRNA结合。 本论文利用的展示技术可以广泛应用于特异靶点的蛋白质筛选,并且本论文筛选到的TS和DHFR亲和肽可以作为TS和DHFR的抑制剂,从而为获得新型的抗肿瘤药物奠定基础。

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The Ligularia-Cremanthodium-Parasenecio (L-C-P) complex of the Tussilagininae (Asteraceae: Senecioneae) contains more than 200 species that are endemic to the Qinghai-Tibetan Plateau in eastern Asia. These species are morphologically distinct; however, their relationships appear complex. A phylogenetic analysis of members of the complex and selected taxa, of the tribe Senecioneae was conducted using chloroplast (ndhF and trnL-F) and nuclear (ITS) sequences. Phylogenetic trees were constructed from individual and combined datasets of the three different sequences. All analyses suggested that Doronicum, a genus that has been included in the Tussilagininae, should be excluded from this subtribe and placed at the base of the tribe Senecioneae. In addition, the Tussilagininae should be broadly circumscribed to include the Tephroseridinae. Within the expanded Tussilagininae containing all 13 genera occurring in eastern Asia, Tussilago and NSPetasites diverged early as a separate lineage, while the remaining I I genera comprise an expanded L-C-P complex clade. We suggest that the L-C-P clade, which is largely unresolved, most likely originated as a consequence of an explosive radiation. The few monophyletic subclades identified in the L-C-P clade with robust support further suggest that some genera of Tussilagininae from eastern Asia require generic re-circumscriptions given the occurrence of subclades containing species of the same genus in different parts of the phylogentic tree due to homoplasy of important morphological characters used to delimit them. Molecular-clock analyses suggest that the explosive radiation of the L-C-P complex occurred mostly within the last 20 million years, which falls well within the period of recent major uplifts of the Qinghai-Tibetan Plateau between the early Miocene to the Pleistocene. It is proposed that significant increases in geological and ecological diversity that accompanied such uplifting, most likely promoted rapid and continuous allopatric speciation in small and isolated populations, and allowed fixation or acquisition of similar morphological characters within unrelated lineages. This phenomenon, possibly combined with interspecific diploid hybridization because of secondary sympatry during relatively stable stages between different uplifts, could be a major cause of high species diversity in the Qinghai-Tibetan Plateau and adjacent areas of eastern Asia. (c) 2005 Elsevier Inc. All rights reserved.

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介绍了一种排爆机器人模拟训练系统.该系统提供了友好的人机交互界面,使操作人员可以进行各种模拟训练,并提高操作水平.重点介绍了该模拟训练系统的体系结构及关键实现技术,包括排爆机器人及其工作环境的建模方法、机器人运动学和动力学简化模型、碰撞检测和技能评定等.通过实验,证明了该模拟训练系统的可行性和有效性.

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西方国家早在20世纪60年代就开始采用防暴机器人处理爆炸物。自从9.11事件后,国际社会恐怖活动更是愈演愈烈,许多国家相继对此给予了高度重视。反恐防暴机器人可应用于核工业、军事、燃化、铁路、公安、武警等部门,代替人在危险、恶劣、有害环境中执行探查、排除或销毁爆炸物、消防、抢救人质以及与恐怖分子对抗等任务。本项目依托课题由最初的“危险作业机器人”到现在的“反恐防暴机器人的产业化研究”,由国家“863”计划资金滚动支持。就现有的反恐防暴机器人,存在速度较慢或机动灵活性不强或可靠性不高等不足,现研究出一种新型反恐防暴机器人,目的是在保证适应一定的非结构环境的前提下(适用所有的非结构环境的移动机构设计是不可取的,也是不现实的),提高机器人本体转向性能和移动速度,降低功耗,机构简单化,同时在硬件与软件设计时采取一些相应的措施,提高其在实际应用环境中的可靠性和抗干扰能力。首先,通过对以往反恐防暴机器人在非结构环境中采用的复合移动机构对比分析研究,提出了一种新型的轮-履带-腿复合移动机构,应用在”灵豹”机器人上。它的特色是移动机构继承了“灵蜥”系列反恐防暴机器人轮与履带移动方式自动切换功能,并且针对“灵蜥”系列机器人轮式移动时,四轮滑动转向灵活性不高、功耗大的问题,提出了三轮式移动机构,在狭小移动空间有着广泛的应用。并对该机器人本体做了运动学分析和稳定性分析,论证了该机构的可行性。其次,根据课题项目研究的需要,在控制方面,主要完成了“灵狐”小型反恐防暴机器人的系统构建与功能实现。通过从事“灵蜥”系列机器人项目开发,积累了一些移动机构设计与分析以及控制系统一些问题解决的实际经验,在“灵狐”控制系统设计过程中,由于采用单片机作为微控制单元,因此着重考虑了提高系统可靠性与抗干扰能力。在“灵狐”机器人样机试验中取得了好的效果,均达到预期目标。

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The rugged surface topography determined the seismic data acquisition construction conditions and the seismic wave explosive and receiver quality in Qaidam Basin. This dissertation systematically researched the seismic acquisition, imaging process and the attribute analysis techniques of complicated oil and gas reservoir. The main research achievements and cognitions are as follows: 1. Through the stimulation effects research and analysis from the aspect of lithologic water-containing differences, it’s specific that stable hydrous sand layer can effectively enhance the stimulation effects combined with the corresponding field tests. The seismic data S/N ratio has been improved due to the combination explosive stimulation. Through the fold number and maximum offset analyses of target horizon, the complicated geometry has been optimized and the S/N ratio of seismic data has been improved, which made an important basis for improvement of 3D seismic data. 2. It has been proved that the first arrival refraction static correction method under the model constraint of fine surface survey is suitable to the Qaidam Basin of western areas by the real seismic data processing. Although the refraction horizon of near surface has some changes in a certain extent, it’s steady basically. The refraction horizon can be continuously traced in sections, so it’s qualified for the refraction static correction method on the whole. 3. The research is based on the curved-ray pre-stack time migration techniques of rough topography, and improved the imaging precision of complex areas. This techniques adopted the constant and variable velocity scanning mode and enhanced the velocity analysis precision. The 3D pre-stack time migration techniques reasonably solved the imaging and velocity multiple solutions problems of steep-dip faults and the intersections of horizontal layers. What’s more, fine velocity analysis and mute are very important to enhance the imaging precision of the seismic data in complicated Wunan areas. 4. The 3D seismic data edge-preserving processing methods have been realized due to the image process techniques. Because this method uses the large range filter, it can attenuate the noise maximally. The faults, break points, lithologic pinchout points and lithologic body of small scale such as river will not be influenced by blur because of the edge-preserving characterization of the method which is really an effective assistant technique of low S/N ratio seismic data attribute analysis. 5. The use of spectral decomposition technique can effectively identify the reservoirs. The special geology body which will not be identified (or without obvious characters) in the seismic profile may be found through the details changes of different frequencies in the amplitude profiles.

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With the development of both seismic theory and computer technology, numerical modeling technology of seismic wave has achieved great advancement during the past half century. The current methods under development include finite differentiation method (FDM), finite element method (FEM), pseudospectral method (PSM), integral equation method (IEM) and spectral element method (SEM). They exert their very important roles in every corner of seismology and seismic prospecting. Large quantity of researches towards spectral element method in the end of last century bring this method to a new era, which results in perfect solution of many difficult problems. However, parts of posterior works such as seismic migration and inversion which base on spectral element method have never been studied widely at least up to the present whereas are of importance to seismic imaging and seismic wave propagation. Based on previous work, this paper uses spectral element method to investigate the characteristics and laws of the seismic wave propagation in isotropic and anisotropic media. By thoroughly studying this high-accuracy method, we implement a kind of reverse-time pre- and post-stack migration based on SEM. In order to verify the validity of the SEM method, we have simulated the propagation of seismic wave in several different models. The simulation results show that: (1) spectral element method can be used to model any complex models and the computational results are comparable with the expected results and the analytic results; (2) the optimum accuracy can be achieved when the rank is between 4 and 9. When it is below 4, the dispersion may occur; and when it is above 9, the time step-length will be changed accordingly with the reducing space step-length in order to keep the computation stability. This will exponentially increase the computation time and at the same time the memory even if simulating the same media. This paper also applies explosive reflection surface imaging technology, time constancy principle of wave-filed extrapolation and least travetime raytracing technology of surface source to SEM pre- and post-stack migration of isotropic and anisotropic media. All imaging results derived by the above methods agree well with the real geological models and the position of interface and inflexions can also return to their right location well. This indicates that the method proposed in this paper is a kind of technology with high accuracy and robust stability. It can serve as an alternative method in real seismic data processing. All these work can boost the development of high-accuracy seismic imaging, and therefore have significant inference value.