758 resultados para TAP
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The expression vector containing phbB and ble genes was constructed and transformed into cell-wall-deficient strain Chlamydomonas reinhardtii CC-849 by the glass-head method. The transgenic alga was selected and maintained in the TAP agar plates containing 10 mug/mL Zeomycin. Transgenic alga, which could express phbB at the transcriptional level, was obtained and further confirmed with PCR, Southern blot and RT-PCR-DNA hybridization analysis.
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随着隐私保护越来越为人们所关注,对匿名认证技术的研究已经成为学术领域的一个热点。本文主要着眼于匿名认证中的匿名凭证与匿名口令认证密钥协商。 在对匿名凭证技术的研究中,本文重点分析了防止凭证出借与凭证匿名更新两个匿名凭证系统性质的实现。 凭证出借是指匿名凭证系统中,用户可以随意将自己的凭证与他人共享,从而使多人可以同时使用一个凭证。本文提出一种新的防止凭证出借方法,并给出一个具体的实现方案。该方法将凭证出借与用户隐私联系起来,通过凭证本身实现防止凭证出借。凭证匿名更新则是指凭证内容进行更新时,凭证颁发方只能知道变更的内容信息,不知道其他任何信息。本文提出一种新的实现方法,在原有凭证的基础上,用相对较少的计算量来实现对凭证内容的更新,使用户匿名得到一个新的凭证。 在对匿名口令认证密钥协商的研究中,本文首先提出了两个攻击方案:针对Shin等人的TAP(t≥2)协议的内部假扮攻击和针对TAP(t≥2)协议以及Viet等人的k-out-of-n APAKE协议的离线字典攻击。前者破坏了协议的认证性,内部攻击者可以假扮服务器与用户建立会话密钥。后者破坏了协议最基本的对口令的安全保护,使得内部攻击者可以离线猜测组内所有用户口令。然后,本文提出了一个新的两方的匿名口令认证密钥协商协议:NAPAKE,并在Square Computational Diffiee-Hellman困难假设以及Decision Inverted-Additive Diffie-Hellman困难假设下证明其安全性。同时,还进一步将其扩展为D-NAPAKE协议,以实现多方的匿名口令认证密钥协商,该协议可以抵抗上面的两个攻击。
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The development of a method for determining arsenic species by capillary zone electrophoresis (CZE) with indirect laser-induced fluorescence (LIF) is described in this paper. The buffer pH, the concentration of fluorescein, the nature and the concentration of the background electrolytes (BGEs) were defined. When 2.0 mM NaHCO3 (pH 9.28) with 10(-7) M fluorescein was used as the buffer, arsenite (As(lll), dimethylarsonic acid (DMA), monomethylarsonic acid (MMA), and arsenate (As(V)) were all separated from one another. The limits of detection for the four arsenic species were p p in the range of 0.12-0.54 mg/L. This method was used in the analysis of spiked arsenic species in tap and mineral water to demonstrate its usefulness. The results showed that both the recovery and the reproducibility of the developed method were acceptable.
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This paper described a laser-excited time-resolved fluoroimmunoassay set. It made lanthanide ion to couple the anhydrde of diethylenetriaminepentaacetic acid (DTPAA) for labeling antibodies. The experiment used polystyrene tap coated with HCV antigen as the solid phase and a chelate of the rare earth metal europium as fluorescent label. A nitrogen laser beam was used to excite the Eu3+ chelates and after 60 ys delay time,the emission fluorescence was measured. Background fluorescence of short lifetimes caused by serum components and Raman scattering can be eliminated by set the delay rime. In the system condition, fluorescent spectra and fluorescent lifetimes of Eu3+ beta-naphthoyltrifluroacetone (NTA) chelates were measured. The fluorescent lifetime value is 650 mu s. The maximum emssion wavelength is 613 nm. The linear range of europium ion concentration is 1 x 10(-7)- 1 x 10(-11) g.mL(-1) and the detection limit is 1 x 10(-13) g.mL(-1). The relative standard deviation of determination ( n = 12) for samples at 0.01 ng.mL(-1) magnitude is 6.4%. Laser-TRFIA was also found to be suitable for diagnosis of HCV. The sensitvity and specificity were comparable to enzyme immunoassay. The result was obtained with laser-TRFIA for 29 human correlated well with enzyme immunoassay.
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Based on Th-230-U-238 disequilibrium and major element data from mid-ocean ridge basalts (MORBs) and ocean island basalts (OIBs), this study calculates mantle melting parameters, and thereby investigates the origin of Th-230 excess. (Th-230/U-238) in global MORBs shows a positive correlation with Fe-8, P (o), Na-8, and F-melt (Fe-8 and Na-8 are FeO and Na2O contents respectively after correction for crustal fractionation relative to MgO = 8 wt%, P (o)=pressure of initial melting and F (melt)=degree of melt), while Th-230 excess in OIBs has no obvious correlation with either initial mantle melting depth or the average degree of mantle melting. Furthermore, compared with the MORBs, higher (Th-230/U-238) in OIBs actually corresponds to a lower melting degree. This suggests that the Th-230 excess in MORBs is controlled by mantle melting conditions, while the Th-230 excess in OIBs is more likely related to the deep garnet control. The vast majority of calculated initial melting pressures of MORBs with excess Th-230 are between 1.0 and 2.5 GPa, which is consistent with the conclusion from experiments in recent years that D (U)> D (Th) for Al-clinopyroxene at pressures of > 1.0 GPa. The initial melting pressure of OIBs is 2.2-3.5 GPa (around the spinel-garnet transition zone), with their low excess Ra-226 compared to MORBs also suggesting a deeper mantle source. Accordingly, excess Th-230 in MORBs and OIBs may be formed respectively in the spinel and garnet stability field. In addition, there is no obvious correlation of K2O/TiO2 with (Th-230/U-238) and initial melting pressure (P (o)) of MORBs, so it is proposed that the melting depth producing excess Th-230 does not tap the spinel-garnet transition zone. OIBs and MORBs in both (Th-230/U-238) vs. K2O/TiO2 and (Th-230/U-238) vs. P (o) plots fall in two distinct areas, indicating that the mineral phases which dominate their excess Th-230 are different. Ce/Yb-Ce curves of fast and slow ridge MORBs are similar, while, in comparison, the Ce/Yb-Ce curve for OIBs shows more influence from garnet. The mechanisms generating excess Th-230 in MORBs and OIBs are significantly different, with formation of excess Th-230 in the garnet zone only being suitable for OIBs.
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由于化石能源储量的日益减少及其燃烧带来的环境污染问题,生物柴油的开发和应用受到广泛关注。微藻因其生长迅速,油脂含量高,被认为是制备生物柴油的理想原料,另外,同陆生油料植物相比,微藻,尤其海洋微藻培养还具有不与农业争耕地和淡水、不影响食物安全保障和破坏生境的优势。然而,由于生产成本较高,微藻生物柴油至今尚未实现商业化生产。大量研究表明,微藻油脂含量和干物质产量受环境条件调控。为优化培养条件,提高微藻的油脂产量,并探索与脂积累相关的某些代谢调控因子,本文研究了铁对三种微藻油脂积累和生长的影响。 首先建立了尼罗红染色、荧光分光光度法测定微藻油脂积累的简单、快速的方法,优化了染色后的小球藻C3和C7(Chlorella vulgaris)、球等鞭金藻(Isochrysis galbana)、三角褐枝藻(Phaeodactylum tricornutum)和莱茵衣藻(Chlamydomonas reinhardtii)脂积累的测量条件。 海洋微藻小球藻C7属于绿藻门,以积累淀粉为主。在指数生长后期向培养基中补加Fe3+,可延长小球藻指数生长期,提高细胞终密度。处于指数生长后期的小球藻经离心收集、重新接种于新的高铁培养基中后,总脂含量能提高到干物质重的56.6%,是低铁培养基中小球藻的3至7倍。 球等鞭金藻属于金藻门,油脂是其贮藏物质的主要形式。在指数生长后期向培养基中补加Fe3+ 后,指数生长期延长,细胞终密度提高。将指数生长后期的球等鞭金藻重新接种于新的培养基中后,在高铁培基中的藻的总脂含量和细胞生长均高于在低铁培养基中的。 最后,研究了铁对淡水藻莱茵衣藻脂积累和生长的影响。指数生长后期的衣藻接种于无铁TAP培养基中后,利用荧光分光光度法测得的中性脂的积累量增加,生长速度下降;而重新接种于高铁培养基中后,脂积累量下降,生长加速。乙酰辅酶A羧化酶(ACCase)催化脂合成的第一步反应,是调节脂合成速度的关键酶。本实验研究结果表明,生长在不同铁浓度条件下的衣藻ACCase基因的表达水平与细胞的分裂、生长相关。
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Two methods for tetrodotoxin analysis using liquid chromatography coupled with electrospray iontrap mass spectrometry (LC-ESI-MS) have been established with C,, reversed phase column and hydrophilic interaction liquid chromatography (HILIC) column, respectively. Sensitivity and reproducibility of the methods were compared. The method using C-18 column in selected ion monitoring (SIM) mode had a detection limit (S/N = 3) of 120 pg, and a good linearity of the calibration curve was obtained for tetrodotoxin (r = 0. 9992). High reproducibility of the method was observed, with a relative standard deviation (RSD) below 10%. The method using HILIC column in SIM mode and selected reaction monitoring (SRM) mode had detection limits (S/N = 3) of 15 and 3.75 pg, respectively. Good linearity of the calibration curves was obtained for tetrodotoxin (r = 0. 9996 and 0. 9998 in SIM and SRM mode, respectively). T he reproducibility was high in SIM mode but relatively poor in SRM mode. Based on the results, the method using HILIC column in SIM mode was suggested for the analysis of tetrodotoxin with LC-MS system.
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The reservoir of Zhongerbei region in Gudao Oilfield is a typical fluvial facies deposit, its serious heterogeneity of the reservoir caused the distribution of remaining oil in mature reservoirs is characterized by highly scattered in the whole field, and result to declination of production, tap potential and stabilize production is more difficult. Reservoir modeling based on lay scale can not fulfill requirement. How to further studied reservoir heterogeneity within the unit and establish the finer reservoir modeling is a valid approach to oil developing. The architectural structure elements analysis is the effectively method to study reservoir heterogeneity. Utilize this method, divide the reservoirs of Gudao Oilfield into ten hierarchies. The priority studying is sixth, seven hierarchies, ie single sand layers sand bodies By the identification of sixth, seven hierarchies, subdivide the reservoir to the single genetic unit. And to subdivide by many correlation means, such as isometry and phase transition, accomplish closure and correlation of 453 wells.Connectting fluvial deposit pattern, deposition characteristic with its log, build the inverting relation between “sedimentary facies” and “electrofacies” The process emphasize genetic communication and collocation structure of genetic body in space. By detailed architecture analyses sandbodies’ structure, this paper recognize seven structure elements, such as major channel, abandoned channel, natural levee, valley flat, crevasse splay, crevasse channel and floodplain fine grain.Combination identification of architectural structure elements with facieology and study of deposition characteristic, can further knowing genesis and development of abandoned channel. It boost the accuracy to separation in blanket channel bodies distribution, and provide reference to retrieving single channel boundary. Finally, establish fine plane and section construction. On basis architectural structure map, barrier beds and interbeds isopach map and mini-structure map, considering single thin layers to be construction unit, the main layer planimetric maps have drawn and the inner oil-water boundary have revealed. All account that architectural structure elements control remaining oil distribution in layer, and develop the study on architectural structure elements to direct horizontal well is succesful.
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A method has been developed for determining of heavy metal ions by field-amplified sample injection capillary electrophoresis with contactless conductivity detection. The effects of the 2-N-morpholinoethanesulfonic acid/histidine (MES/His) concentration in the sample matrix, the injection time and organic additives on the enrichment factor were studied. The results showed that MES/His with a low concentration in the sample matrix, an increase of the injection time and the addition of acetonitrile improved the enrichment factor. Four heavy metal ions (Zn2+, Co2+, Cu2+ and Ni2+) were dissolved in deionized water, separated in a 10 mM MES/His running buffer at pH 4.9 and detected by contactless conductivity detection. The detection sensitivity was enhanced by about three orders of magnitude with respect to the non-stacking injection mode. The limits of detection were in the range from 5 nM (Zn2+) to 30 nM (Cu2+). The method has been used to determine heavy metal ions in tap water.
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The bifunctional complex [Ru(TAP)(2)POQ-Nmet](2+), 1, formed with a [Ru(TAP)(2)Phen](2+) metallic unit linked to a quinoline moiety, and [Ru(TAP)(2)Phen](2+), 2, as reference, have been tested as photoprobes of DNA. Interestingly, 1 exhibits an emission enhancement of a factor of 16-17 upon binding to calf thymus DNA. Moreover, this emission is modulated by the nucleic base content of the polynucleotide. It varies by almost an order of magnitude from a polynucleotide containing 100% of G-C to a guanine-free nucleic acid where the excited-state lifetime reaches about 2 micros. The origins of these interesting properties are analyzed by comparing 1 with reference 2 in the presence of different polynucleotides.
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Novel bifunctional ruthenium(n) complexes, [Ru(TAP)2(POQ-Nmet)]2+ and [Ru(BPY)2(POQ-Nmet)]2+(la, 2a), containing a metallic and an organic moiety, have been prepared as photoprobes and photoreagents of DNA(TAP = 1,4,5,8-tetraazaphenanthrene, POQ-Nmet = 5-[6-(7-chloroquinolin-4-yl)-3-thia-6-azaheptanamido]-l,10phenanthroline). The ES mass spectrometry and 'H NMR data in organic solvents indicate that the quinoline moiety exists in both the protonated and non-protonated form. Moreover, the comparison of the NMR data with those of the corresponding monofunctional complexes(without quinoline) evidences that [Ru(TAP).2(POQ-Nmet)]2+ and [Ru(BPY)J(POQ-Nmet)]2+ are unfolded when the quinoline unit is protonated whereas deprotonation permits folding of the molecule. In the folded state the spatial proximity of the electron donor(the organic moiety) and electron acceptor(the metallic moiety) in [Ru(TAP)2(POQ-Nmet)]2+ favours intramolecular photo-induced electron transfer, which has been shown in a previous study to be responsible for the very low luminescence of la in non-protonating solutions. The restoration of the luminescence by protonation of the quinoline moiety as observed previously is in agreement with the unfolding of the molecule demonstrated in this work. The existence of such folding-unfolding processes related to protonation is crucial for studies of la with DNA. © The Royal Society of Chemistry 2000.
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Inverse diffraction consists in determining the field distribution on a boundary surface from the knowledge of the distribution on a surface situated within the domain where the wave propagates. This problem is a good example for illustrating the use of least-squares methods (also called regularization methods) for solving linear ill-posed inverse problem. We focus on obtaining error bounds For regularized solutions and show that the stability of the restored field far from the boundary surface is quite satisfactory: the error is proportional to ∊(ðŗ‚ ≃ 1) ,ðŗœ being the error in the data (Hölder continuity). However, the error in the restored field on the boundary surface is only proportional to an inverse power of │In∊│ (logarithmic continuity). Such a poor continuity implies some limitations on the resolution which is achievable in practice. In this case, the resolution limit is seen to be about half of the wavelength. Copyright © 1981 by The Institute of Electrical and Electronics Engineers, Inc.
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[Ru(BPY)2POQ-Nmet]2+ and [Ru(TAP)2POQ-Nmet]2+ (1 and 3) are bifunctional complexes composed of a metallic unit linked by a flexible chain to an organic unit. They have been prepared as photoprobes or photoreagents of DNA. In this work, the spectroscopic properties of these bifunctional complexes in the absence of DNA are compared with those of the monofunctional analogues [Ru(BPY)2Phen]2+, [Ru-(BPY)2acPhen]2+, [Ru(TAP)2Phen]2+, and [Ru(TAP)2acPhen]2+ (2 and 4). The electrospray mass spectrometry and absorption data show that the quinoline moiety exists in the protonated and nonprotonated form. Although the bifunctional complex containing 2,2′-bipyridine (BPY) ligands exhibits photophysical properties similar to those of the monofunctional compounds, the bifunctional complex with 1,4,5,8-tetraazaphenanthrene (TAP) ligands behaves quite differently. It has weaker relative emission quantum yields and shorter luminescence lifetimes than the monofunctional TAP analogue when the quinoline unit is nonprotonated. This indicates an efficient intramolecular quenching of the 3MLCT (metal to ligand charge transfer) excited state of the TAP metallic moiety. When the organic unit is protonated, there is no internal quenching. In organic solvent, the nonquenched excited metallic unit (bearing a protonated quinoline) and the quenched one (bearing a nonprotonated organic unit) are in slow equilibrium as compared to the lifetime of the two emitters. In aqueous solution this equilibrium is faster and is catalysed by the presence of phosphate buffer. Flash photolysis experiments suggest that the intramolecular quenching process originates from a photoinduced electron transfer from the nonprotonated quinoline to the excited Ru(TAP)2 2+ moiety.
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Pulse design is investigated for time-reversal (TR) imaging as applied to ultrawideband (UWB) breast cancer detection. Earlier it has been shown that a suitably-designed UWB pulse may help to improve imaging performance for a single-tumor breast phantom with predetermined lesion properties. The current work considers the following more general and practical situations: presence of multiple malignancies with unknown tumor size and dielectric properties. Four pulse selection criteria are proposed with each focusing on one of the following aspects: eliminating signal clutter generated by tissue inhomogeneities, canceling mutual interference among tumors, improving image resolution, and suppressing artifacts created by sidelobe of the target response. By applying the proposed criteria, the shape parameters of UWB waveforms with desirable characteristics are identified through search of all the possible pulses. Simulation example using a numerical breast phantom, comprised of two tumors and structured clutter distribution, demonstrates the effectiveness of the proposed approach. Specifically, a tradeoff between the image resolution and signal-to-clutter contrast (SCC) is observed in terms of selection of the excitation waveforms.
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It has been proposed that the field of appropriate technology (AT) - small-scale, energy efficient and low-cost solutions, can be of tremendous assistance in many of the sustainable development challenges, such as food and water security, health, shelter, education and work opportunities. Unfortunately, there has not yet been a significant uptake of AT by organizations, researchers, policy makers or the mainstream public working in the many areas of the development sector. Some of the biggest barriers to higher AT engagement include: 1) AT perceived as inferior or ‘poor persons technology’, 2) questions of technological robustness, design, fit and transferability, 3) funding, 4) institutional support, as well as 5) general barriers associated with tackling rural poverty. With the rise of information and communication technologies (ICTs) for online networking and knowledge sharing, the possibilities to tap into the collaborative open-access and open-source AT are growing, and so is the prospect for collective poverty reducing strategies, enhancement of entrepreneurship, communications, education and a diffusion of life-changing technologies. In short, the same collaborative philosophy employed in the success of open source software can be applied to hardware design of technologies to improve sustainable development efforts worldwide. To analyze current barriers to open source appropriate technology (OSAT) and explore opportunities to overcome such obstacles, a series of interviews with researchers and organizations working in the field of AT were conducted. The results of the interviews confirmed the majority of literature identified barriers, but also revealed that the most pressing problem for organizations and researchers currently working in the field of AT is the need for much better communication and collaboration to share the knowledge and resources and work in partnership. In addition, interviews showcased general receptiveness to the principles of collaborative innovation and open source on the ground level. A much greater focus on networking, collaboration, demand-led innovation, community participation, and the inclusion of educational institutions through student involvement can be of significant help to build the necessary knowledge base, networks and the critical mass exposure for the growth of appropriate technology.