378 resultados para AK17-1454


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羊栖菜是重要的大型经济海藻之一,在食品、医药、化工领域都有广泛应用。本研究对羊栖菜养殖生产中常见的品系“鹿丰1号”及另外2种品系进行了DNA指纹分析及遗传变异的研究,构建了遗传指纹图谱,分析了不同种群的遗传关系,为羊栖菜的种质鉴定及遗传选育提供了理论依据。 运用RAPD分子标记技术,对5个羊栖菜的种群中共125个个体进行了分析,从300个引物中筛选出12条随机扩增引物共扩增135个位点,多态位点比率为84.4%。从中选择了4个多态性位点,构建了5种羊栖菜DNA指纹图谱,并获得了“鹿丰1号”SCAR标记。另外,进行了5种羊栖菜种群的遗传背景的分析,结果表明“鹿丰1号”与品系2可以明显的与野生种群分开。根据Dice常数计算所得的5个种群的遗传距离在0.1116-0.2563之间。 运用ISSR分子标记技术,对5个种群的125个羊栖菜个体进行分析,通过90条引物的筛选,获得10条ISSR引物,扩增出92个位点,多态位点比率为67.4%。5个种群的遗传距离在0.0863-0.1454之间。 本研究以铜藻作为外群,通过2种遗传标记分析,证明铜藻与5种羊栖菜种群的遗传距离均远远大于其种群之间的遗传距离;另外,“鹿丰1号”不同年份的种群之间的遗传距离均为其中的最小值,相关结果对羊栖菜遗传选育和种质鉴定等有参考价值。

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卵泡抑素(Follistatin)是1987年由Robertson和Ueno分别从牛和猪的卵泡液中分离出的一种富含半胱氨酸的糖基化单链多肽。FS对不同类型的细胞有广泛的调节作用,具有多方面的生物学作用。本研究克隆到牙鲆Follistatin基因,并利用RT-PCR和原位杂交对其在胚胎及成体中的表达进行了分析,并对其启动子进行了组织特异性分析。 1. Follistatin基因组全长4.3 kb左右,其中启动子区长约1 kb。与cDNA序列的比较显示该基因含有5个外显子和4个内含子,内含子和外显子的交界处严格遵守GT…AG规则。Follistatin基因编码了一个含有323个氨基酸的蛋白质前体,该蛋白质前体含有信号肽区域、N-端结构域、Follistatin结构域Ⅰ、Follistatin结构域Ⅱ、Follistatin结构域Ⅲ和C-端结构域。蛋白比较分析表明Follistatin与其他物种的Follistatin的同源性较高,其结构域保守性更高。 三级预测结果显示:在空间构型上,牙鲆Follistatin基因与斑马鱼Follistatin基因完全一致。在序列上高度保守的半胱氨酸在空间上两两相对,它们可能对维持Follistatin蛋白的空间结构起着重要的作用 2. RT-PCR方法和原位杂交方法研究Follistatin基因在牙鲆胚胎中的表达情况结果显示:Follistatin基因在受精后26 hrs开始在中胚层细胞处表达,其后在受精后28、30、32、34、36、38、40、42 hrs等时期Follistatin基因持续表达,并在体节腹部部位、头部,背部体节等部位表达。以MyoD为对照而进行的双色原位杂交结果显示:Follistatin与MyoD在胚胎的体节处表达有重叠区域,对双色原位杂交样品进行的冰冻切片实验结果显示:两个基因的表达区域交叉,互相混合,表明Follistatin基因也在肌肉前体细胞中表达,但并不在所有的前体细胞中表达,Follistatin可能在肌肉发育早期起一定的作用。成体组织中,Follitatin基因在体肾、肠、心脏、头肾、脾中有表达,而在肌肉中没有表达。 3.启动子序列分析结果表明:牙鲆启动子存在AP-1、C/EBP、SP1、USF、E47、MyoD等转录因子的潜在结合位点。显微注射结果显示:该基因启动子能够使绿色荧光蛋白表达在斑马鱼的胚胎肌肉组织中。

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本发明涉及一种绿色植物生长调节剂及其制备工艺,该调节剂是由宽叶独行菜、微量元素、水制成,其制备工艺是将宽叶独行菜用水加热浸提后至用试剂检验无明显氨基酸反应止,并减压回收后备用;本发明是从天然植物资源中提取制备是无毒、高效价廉的调节剂,可促进种子萌发、根粗苗壮;增强植物分孽、分枝能力,增加千粒重;具有稳定的增产、增质效果;该植物生长调节剂性能稳定,可拌种、浸种、喷放,并能和其它农药、除草剂、微量元素肥料等混合使用;可使小麦产量增产5—10%,使蔬菜产量增产10—50左右;其制备工艺简单可靠。

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Binding, David; Bell, D.; Walters, K., (2006) 'The Oscillatory Squeeze flow rheometer: Comprehensive theory and a new experimental facility', Rheologica Acta 46 pp.111-121 RAE2008

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Research around ingesting /public perceptions of ‘secret’ and exploring other narratives around our perceptions of food and eating.

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This paper investigates the application of a non-destructive ultrasonic technique for characterising the rheological properties of solder paste through the use of through-mode microsecond ultrasonic pulses for evaluation of viscoelastic properties of lead-free solder paste containing different types of flux. Ultrasonic techniques offer a robust and reliable form of non-destructive testing of materials where access to the sample is restricted or when sample handling can interfere with the monitoring or analysis process due to externally incorporated changes to the material’s physical state or accidental contamination during the removal or testing process. Ultrasonic based techniques are increasingly used for quality control and production monitoring functions which requires evaluation of changes in material properties for a wide range of industrial applications such as cement paste quality, plastic/polymer extrusion process, dough and even sugar content in beverage drinks. In addition, ultrasound techniques are of great interest for their capability to take rapid measurements in systems which are optically opaque. The conventional industry approach for characterising the rheological properties of suspensions during processing/packaging stage is mainly through the use of viscometer and some through the use of rheometer. One of the potential limitations of viscometer and rheometer based measurements is that the collection and preparation of the solder paste samples can irreversibly alter the structure and flow behaviour of the sample. Hence the measurement may not represent the actual quality of the whole production batch. Secondly, rheological measurements and the interpretation of rheological data is a very technical and time consuming process, which requires professionally trained R&D personnel. The ultrasound technique being proposed provides simple, yet accurate and easy to use solution for the in-situ rheological characterisation of solder pastes which will benefit the materials suppliers (who formulate and produce solder pastes) and solder paste consumers (especially, contract electronics manufacturers). The results from the work show that the technique can be used by R&D personnel involved in paste formulation and manufacture to monitor the batch-to-batch quality and consistency.

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Bioresorbable polymers such as polylactide (PIA) and polylactide-co-glycolide (PLGA) have been used successfully as biomaterials in a wide range of medical applications. However, their slow degradation rates and propensity to lose strength before mass have caused problems. A central challenge for the development of these materials is the assurance of consistent and predictable in vivo degradation. Previous work has illustrated the potential to influence polymer degradation using electron beam (e-beam) radiation. The work addressed in this paper investigates further the utilisation of e-beam radiation in order to achieve a more surface specific effect. Variation of e-beam energy was studied as a means to control the effective penetrative depth in poly-L-lactide (PLEA). PLEA samples were exposed to e-beam radiation at individual energies of 0.5 MeV, 0.75 MeV and 1.5 MeV. The near-surface region of the PLEA samples was shown to be affected by e-beam irradiation with induced changes in molecular weight, morphology, flexural strength and degradation profile. Moreover, the depth to which the physical properties of the polymer were affected is dependent on the beam energy used. Computer modelling of the transmission of each e-beam energy level used corresponded well with these findings. (C) 2010 Elsevier Ltd. All rights reserved.

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This paper outlines the use of phasor measurement unit (PMU) records to validate models of fixed speed induction generator (FSIG)-based wind farms during frequency transients. Wind turbine manufacturers usually create their own proprietary models which they can supply to power system utilities for stability studies, subject to confidentiality agreements. However, it is desirable to confirm the accuracy of supplied models with measurements from the particular installation, in order to assess their validity under real field conditions. This is prudent due to possible changes in control algorithms and design retrofits, not accurately reflected or omitted in the supplied model. One important aspect of such models, especially for smaller power systems with limited inertia, is their accuracy during system frequency transients. This paper, therefore, assesses the accuracy of FSIG models with regard to frequency stability, and hence validates a subset of the model dynamics. Such models can then be used with confidence to assess wider system stability implications. The measured and simulated response of a wind farm using doubly fed induction generator (DFIG) technology is also assessed.

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Both Anderson and Gatignon and the Uppsala internationalization model see the initial mode of foreign market entry and subsequent modes of operation as unilaterally determined by multinational enterprises (MNEs) arbitraging control and risk and increasing their commitment as they gain experience in the target market. OLI and internalization models do recognize that foreign market entry requires the bundling of MNE and complementary local assets, which they call location or country-specific advantages, but implicitly assume that those assets are freely accessible to MNEs. In contrast to both of these MNE-centric views, I explicitly consider the transactional characteristics of complementary local assets and model foreign market entry as the optimal assignment of equity between their owners and MNEs. By looking at the relative efficiency of the different markets in which MNE and complementary local assets are traded, and at how these two categories of assets match, I am able to predict whether equity will be held by MNEs or by local firms, or shared between them, and whether MNEs will enter through greenfields, brownfields, or acquisitions. The bundling model I propose has interesting implications for the evolution of the MNE footprint in host countries, and for the reasons behind the emergence of Dragon MNEs.

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We undertake a detailed study of the sets of multiplicity in a second countable locally compact group G and their operator versions. We establish a symbolic calculus for normal completely bounded maps from the space B(L-2(G)) of bounded linear operators on L-2 (G) into the von Neumann algebra VN(G) of G and use it to show that a closed subset E subset of G is a set of multiplicity if and only if the set E* = {(s,t) is an element of G x G : ts(-1) is an element of E} is a set of operator multiplicity. Analogous results are established for M-1-sets and M-0-sets. We show that the property of being a set of multiplicity is preserved under various operations, including taking direct products, and establish an Inverse Image Theorem for such sets. We characterise the sets of finite width that are also sets of operator multiplicity, and show that every compact operator supported on a set of finite width can be approximated by sums of rank one operators supported on the same set. We show that, if G satisfies a mild approximation condition, pointwise multiplication by a given measurable function psi : G -> C defines a closable multiplier on the reduced C*-algebra G(r)*(G) of G if and only if Schur multiplication by the function N(psi): G x G -> C, given by N(psi)(s, t) = psi(ts(-1)), is a closable operator when viewed as a densely defined linear map on the space of compact operators on L-2(G). Similar results are obtained for multipliers on VN(C).