914 resultados para Myrmecophilous fly


Relevância:

10.00% 10.00%

Publicador:

Resumo:

The fundamental principle behind the development of SCC has been the nanoscale tailoring of cementitious matrices. Although self-compacting concrete (SCC) is currently used in many countries, there is a fundamental lack of the intrinsic durability of the material itself. The scope of the current paper is to present the outcomes of a research study on some principal indicators (porosity and capillary absorption) that define the durability of SCC, and how these are compared with the corresponding parameters of conventional concrete. Furthermore, this paper investigates the addition of industrial by-products, such as fly-ash or lime powder, to SCC mixtures and their effect on the durability indicators.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We demonstrate autonomous construction of structures using a robot arm that can fabricate threads of TPA (Thermoplastic Adhesive) in free space on the fly. TPA has many important material properties that help to greatly simplify the otherwise complex task of building structures in complex environments. We present a model for the formation of TPA strings based on plastic deformation which also includes the temperature dependent material properties which change significantly as the thread is formed and cools. Experiments of drawing TPA show that drawing forces due to the viscosity of the TPA are more dominated by the speed of drawing than the changes in viscosity due to temperature. The load bearing capacity of individual strings is also modelled and measured and structures are built using the TPA strings which due to the adhesiveness can be anchored to a wide range surfaces as well as to other strings. © 2013 IEEE.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A model for off-wall boundary conditions for turbulent flow is investigated. The objective of such a model is to circumvent the need to resolve the buffer layer near the wall, by providing conditions in the logarithmic layer for the overlying flow. The model is based on the self-similarity of the flow at different heights in the logarithmic layer. It was first proposed by Mizuno and Jiménez (2013), imposing at the boundary plane a velocity field obtained on-the-fly from an overlying region. The key feature of the model was that the lengthscales of the field were rescaled to account for the self-similarity law. The model was successful at sustaining a turbulent logarithmic layer, but resulted in some disagreements in the flow statistics, compared to fully-resolved flows. These disagreements needed to be addressed for the model to be of practical application. In the present paper, a more refined, wavelength-dependent rescaling law is proposed, based on the wavelength-dependent dynamics in fully-resolved flows. Results for channel flow show that the new model eliminates the large artificial pressure fluctuations found in the previous one, and a better agreement is obtained in the bulk properties, the flow fluctuations, and their spectral distribution across the whole domain. © Published under licence by IOP Publishing Ltd.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Extraction experiments with spiking of C-13(12)-PCDD/Fs were performed with a variety of PCDD/Fs contaminated samples. The extraction recovery of PCDD/Fs was mainly influenced by PCDD/Fs concentration and the sample matrix. Generally, the first soxhlet extraction with toluene has suitable recovery. From the selected samples, only FAMS4 and 5 which are fly ashes with high concentration, the recovery of the first soxhlet extraction with 24 hr. is low, but PCDD/Fs were almost completely removed after 72 hr. Copyright (C) 1996 Elsevier Science Ltd

Relevância:

10.00% 10.00%

Publicador:

Resumo:

许多系统需要在规定时间内响应外部发生的事件,并迅速完成对事件的处理,这样的系统称之为实时系统。实时系统经常出现在与生命财产安全息息相关的领域,如果无法及时响应外部事件,可能会造成十分严重的后果。如何保证实时系统的正确性、可靠性受到越来越广泛的关注。 模型检测是一种对系统进行形式化验证的算法,它可以自动的在模型状态空间中搜索不满足规范的路径或状态,设计者可以根据找到的反例修改系统设计,进而提高系统的可靠性。模型检测方法的主要瓶颈是状态爆炸,符号化方法和抽象是延缓状态爆炸发生的重要手段。 时间自动机是一种使用广泛的描述实时系统的数学模型, 时序逻辑LTL是是一种常用的针对实时和并发系统的规范语言,本文主要研究了时间自动机关于LTL性质的符号化模型检测方法,并实现了相应的模型检测工具CTAV。 CTAV以DBM作为表示符号化状态的数据结构,使用DBM的操作和运算完成符号化状态的生成、存储及比较等,它通过on-the-fly的方法在生成系统符号化状态空间的同时进行性质的检测。 本文还研究了最大上下界抽象等在模型检测中的使用,比较了不同的抽象在LTL模型检测中的效果。此外还针对符号化状态的特点,对模型检测过程进行了改进,避免了不必要的状态展开。 为了方便建模,CTAV对UPPAAL模型描述语言进行了支持,并针对检测过程中变量存储的各种情况,设计了一次索引和二次索引的方法提高读写变量的速度。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

本实验室果蝇研究工作,主要集中在黑腹果蝇的新基因起源的研究。新基因起源的分子机制主要包括:外显子重排、基因复制、基因逆转座、移动元件介导、基因水平转移、基因从头起源、基因的断裂融合。为了阐述这些新基因的产生和它们所带来的物种适应性,我们对这些新近起源的基因进行了功能研究。但是,仅仅限于新基因所在物种的功能研究并不能完全解释新基因产生的进化原因,我们需要了解它是否能够给没有该基因的果蝇物种带来一定的适应性。例如一些生殖相关新基因,如果我们将它们转入没有该基因的果蝇,那是否能够给该果蝇带来生殖能力的提高?无论结果如何,这都为我们研究新基因的起源提供一个重要线索。由此,黑腹果蝇以外的其它果蝇物种中实现转基因成为该研究的重要技术环节。但是,实验室目前的转基因系统仅限于P转座子介导的黑腹果蝇转基因系统,因而我们需要建立一种新的转基因平台。而转座子Minos打破物种范围的转基因特性,以及它的转座特点为我们提供了选择。转座子Minos是从果蝇D. hydei中克隆出来长约1.8kb的Ⅱ型转座子,Tc1家族转座元件成员。Minos的转座机制与大部分转座子一样,在宿主基因组里面实行着剪切和粘贴的运作机制。Minos在转座时,偏向插入TA位点并且主要集中于内含子区域,这样可以减少对插入位置基因的影响。此外,Minos在黑腹果蝇中的转座效率约30%,并且拥有一套成熟的选择标记。因此,Minos成为我们解决非黑腹果蝇转基因技术难题的首选。 在本文的工作中,我们采用由希腊Savakis教授(希腊分子生物学与生物技术研究所)提供的Minos转基因系统,完成果蝇的转基因实验。在这套转基因系统中,非自主的转座子Minos和转座酶基因被克隆到了不同载体当中。其中Minos转座子序列中插入了由3xP3眼睛特异表达的启动子介导表达的eGFP报告基因,而转座酶基因则由热激蛋白hsp70启动子调控表达。实验过程中,我们在果蝇D. melanogaster 和D. yakuba的胚胎中分别同时显微注射入含有转座子和转座酶本实验室果蝇研究工作,主要集中在黑腹果蝇的新基因起源的研究。新基因起源的分子机制主要包括:外显子重排、基因复制、基因逆转座、移动元件介导、基因水平转移、基因从头起源、基因的断裂融合。为了阐述这些新基因的产生和它们所带来的物种适应性,我们对这些新近起源的基因进行了功能研究。但是,仅仅限于新基因所在物种的功能研究并不能完全解释新基因产生的进化原因,我们需要了解它是否能够给没有该基因的果蝇物种带来一定的适应性。例如一些生殖相关新基因,如果我们将它们转入没有该基因的果蝇,那是否能够给该果蝇带来生殖能力的提高?无论结果如何,这都为我们研究新基因的起源提供一个重要线索。由此,黑腹果蝇以外的其它果蝇物种中实现转基因成为该研究的重要技术环节。但是,实验室目前的转基因系统仅限于P转座子介导的黑腹果蝇转基因系统,因而我们需要建立一种新的转基因平台。而转座子Minos打破物种范围的转基因特性,以及它的转座特点为我们提供了选择。转座子Minos是从果蝇D. hydei中克隆出来长约1.8kb的Ⅱ型转座子,Tc1家族转座元件成员。Minos的转座机制与大部分转座子一样,在宿主基因组里面实行着剪切和粘贴的运作机制。Minos在转座时,偏向插入TA位点并且主要集中于内含子区域,这样可以减少对插入位置基因的影响。此外,Minos在黑腹果蝇中的转座效率约30%,并且拥有一套成熟的选择标记。因此,Minos成为我们解决非黑腹果蝇转基因技术难题的首选。 在本文的工作中,我们采用由希腊Savakis教授(希腊分子生物学与生物技术研究所)提供的Minos转基因系统,完成果蝇的转基因实验。在这套转基因系统中,非自主的转座子Minos和转座酶基因被克隆到了不同载体当中。其中Minos转座子序列中插入了由3xP3眼睛特异表达的启动子介导表达的eGFP报告基因,而转座酶基因则由热激蛋白hsp70启动子调控表达。实验过程中,我们在果蝇D. melanogaster 和D. yakuba的胚胎中分别同时显微注射入含有转座子和转座酶所在的质粒。转座酶在37度条件诱导下进行表达,协助Minos完成转座过程。在转基因果蝇的阳性筛选中,我们利用眼睛特异表达的绿色荧光蛋作为选择标记。并且,我们通过PCR实验进一步验证了转基因果蝇的真实性。本研究中,我们对转基因实验条件进行了初步优化。我们通过对黑腹果蝇白眼突变品系W1118和D. yakuba注射后胚胎进行保湿,对D. yakuba注射胚胎进行非退壳处理。在改进条件下W1118和D. yakuba的存活率分别为10%和3%左右。通过筛选转基因阳性果蝇,我们得出Minos在W1118和D. yakuba中的转座效率分别在32%和20%左右。我们的实验结果再一次证实了Minos在果蝇D. melanogaster中可行性。同时,该工作也初步完成了在果蝇D. yakuba 中的第一次Minos介导的转基因实验,为新基因的跨物种功能研究奠定了实验基础。在未来的工作计划中,我们将采用Minos转基因系统,把实验室目前研究的黑腹果蝇新基因导入其它物种果蝇进行功能研究。 水稻是一种重要的世界粮食作物,世界上过半的人口以水稻为主食。水稻相对别的粮食作物来讲具有较小的基因组,并且拥有较好的基因组注释,是一种理想的单子叶模式生物。植物转基因技术的发展推动着水稻功能基因组学的研究,目前水稻的转基因技术主要依赖于土壤细菌农杆菌(Agrobacterium tumefaciens)T-DNA介导的外源基因染色体插入。在自然状态下,农杆菌的T-DNA位于Ti致瘤质粒当中。它包括了一些转座元件和一些帮助T-DNA转座的毒性蛋白基因和调节基因。由于Ti质粒上的T-DNA太长,并且没有太多的酶切位点,因此自然状态的T-DNA不适合进行转基因实验。为了方便T-DNA的实际应用,研究人员创立了双载体转基因系统。T-DNA转座区被分离到出Ti载体,并且装载到另外一个适合实验操作的质粒当中,而毒性蛋白表达基因等则保留在Ti质粒上。因此,在进行T-DNA介导的转基因实验时,需要同时存在T-DNA载体和Ti质粒。 本文以“水稻注释计划数据库RAP-DB”的表达数据为参考,选择了60个高表达基因的启动子区域进行克隆。通过对T-DNA载体pCAMBIA1301 进行改造,去掉其原来的35S启动子,将预测的基因启动子克隆到该载体中并与报告基 摘要 因GUS 基因融合。通过分子克隆实验,我们得到了45个高表达基因的启动子载体。最终,为了测试这45个启动子的启动效率,我们会将它们转化到水稻愈伤组织中通过启动子融合的GUS基于表达情况来判断我们启动子的启动效率。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In this work, studies were carried out on the extraction properties of Mn(II) and MnO4- in sulfuric acid medium using Cyanex 923. Effects of different variables on the extraction of Mn(II) and MnO4-, such as the concentrations of acid, the extractant, and the temperature, were investigated. Results indicated that Mn(II) was extracted weakly by Cyanex 923; however, MnO4- could be strongly extracted into the organic phase. The extraction mechanism of MnO4- was proposed, and the influence of MnO4- on the extraction of cerium was identified when KMnO4 as oxidizer added into the bastnasite sulfuric acid leaching liquor. As MnO4- was easier to be extracted into the organic phase than Ce(IV) and then lost its ability for oxidization, a new device was designed to realize sufficient oxidization of cerium from III to IV, and which has been applied to industrialization.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Selenium binding proteins (SeBP) represent a family of proteins that are believed to be involved in controlling the oxidation/reduction in many physiological processes. The cDNA of Zhikong Scallop Chlamys farreri selenium binding protein (zSeBP) was cloned by expressed sequence tag (EST) and RACE techniques. The high similarity of zSeBP deduced amino acid sequence with the SeBP in other organisms, such as bird, fish, frog, mosquito, fruit fly, mammalian, and even nematode and microorganism indicated that zSeBP should be a member of SeBP family. The temporal expression of zSeBP in the hemocytes was measured by semi-quantitative RT-PCR after scallops were stimulated by either oxidative stress or microbial challenge. The expression of zSeBP was up-regulated progressively after stimulation, and then dropped gradually to the original level. Meanwhile, malondialdehyde (MDA) measured by the colorimetric method in the microbial challenged scallops increased immediately after scallops was challenged by microbes, and was significantly higher than that in the control scallops. Results indicated that the microbial infection could incense the disorder of oxidation/reduction and may result in high MDA production. The negative correlation between the expression level of zSeBP and the MDA content suggested that zSeBP could play an important role in mediating the anti-oxidation mechanisms and immune response in marine invertebrates. (c) 2005 Published by Elsevier Ltd.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A novel manganese superoxide dismutase (MnSOD) was cloned from bay scallop Argopecten irradians by 3' and 5' rapid amplification of cDNA ends (RACE) PCR. The full-length cDNA of MnSOD was of 1207 bp with a 678 bp open reading frame encoding 226 amino acids. The deduced amino acid sequence contained a putative signal peptide of 26 amino acids. Sequence comparison showed that the MnSOD of A. irradians shared high identity with MnSOD in invertebrates and vertebrates, such as MnSOD from abalone Haliotis discus discus (ABG88843) and frog Xenopus laevis (AAQ63483). Furthermore, the 3D structure of bay scallop MnSOD was predicted by SWISS-MODEL Protein Modelling Server and compared with those of other MnSODs. The overall structure of bay scallop MnSOD was similar to those of zebrafish Danio rerio, fruit fly Drosophila melanogaster, Chinese shrimp Fenneropenaeus chinensis, human Homo sapiens, and had the highest similarity to scallop Mizuhopecten yessoensis and abalone H. discus discus. A quantitative real-time PCR (qRT-PCR) assay was developed to detect the mRNA expression of MnSOD in different tissues and the temporal expression in haemocytes following challenge with the bacterium Vibrio anguillarum. A higher-level of mRNA expression of MnSOD was detected in gill and mantle. The expression of MnSOD reached the highest level at 3 h post-injection with V. anguillarum and then slightly recovered from 6 to 48 h. The results indicated that bay scallop MnSOD was a constitutive and inducible protein and thus could play an important role in the immune responses against V anguillarum infection. (c) 2008 Elsevier Ltd. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

本文针对旋翼飞行机器人全包线机动飞行中的驱动器滞后以及动力学模型时变的问题,提出了应对不确定性动力学模型的基于模型差分析的增量平稳预测控制方法。该方法首先通过建立增量平稳预测过程模型来应对驱动器输出滞后与稳态模型以及系统工作点的不确定性,并提升控制系统鲁棒性。然后通过自适应集员滤波器在线估计系统瞬态动力学与名义模型的偏差来补偿全包线飞行中时变模型对于名义控制器跟踪性能的影响。最后,通过实际的飞行试验验证了此方法能够有效的解决全包线飞行中航向与垂向的驱动器滞后与动力学时变问题,并且可以实用于旋翼机器人航向与垂向的全包线自主飞行控制。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Distributions of elements especially hazard trace elements in coals and their wastes from a coal fired power plant have been studied in detail using knowledge of Geology, Mineralogy, Geochemistry and Environmental chemistry. The key work is on the small particle sizes of fly ashes which escaped from electric precipitator and discharged into atmosphere. By means of X-ray powder diffraction (XRD) and scanning electron microscopy with energy-dispersive spectrometer (SEM-EDS), the characteristics of minerals and morphologies were studied. Different types of fly ash were formed in different stages and processes. More than 50% of small fly ashes belonged to inhalable particles (PM10). The very fine fly ashes preferred to attach on surface of bigger fly ash or conglutinate with each other and this decreased the environmental impact of tiny fly ashes. The trace elements in coal, fly ashes, slags and small particle sizes of fly ashes had been analysed by means of Neutron Activation Analysis (INAA), inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma atomic emission spectrometry (ICP-AES). As particle sizes decreasing, distributions of most elements increased, but in contrary to most studies, this increasing trend was not very obviously because of the tendency of attachment of tiny fly ashes. The occurrence of 30 elements including hazard trace elements of Cd, Cr, Ni, Co, Pb, Zn, As, Se, Cu, V was studied by means of sequential chemical extract. The annual discharge of hazard trace elements of slag, fly ash, small fly ash (PM10), tiny fly ash (PM2.5) and air was calculated by mass balance. S, V, Cu, Pb, Se, Mo, Cd from power plant had potential impacts on environment. Hazard trace elements from the power plant had little effect on soil and aerosol comparing to those from other industrial sources and the effects were mostly on downwind direction. Both the high performance electric precipitator and high chimney made the hazard trace elements from power plant being transported far away but little environmental impacts.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

I have invented "Internet Fish," a novel class of resource-discovery tools designed to help users extract useful information from the Internet. Internet Fish (IFish) are semi-autonomous, persistent information brokers; users deploy individual IFish to gather and refine information related to a particular topic. An IFish will initiate research, continue to discover new sources of information, and keep tabs on new developments in that topic. As part of the information-gathering process the user interacts with his IFish to find out what it has learned, answer questions it has posed, and make suggestions for guidance. Internet Fish differ from other Internet resource discovery systems in that they are persistent, personal and dynamic. As part of the information-gathering process IFish conduct extended, long-term conversations with users as they explore. They incorporate deep structural knowledge of the organization and services of the net, and are also capable of on-the-fly reconfiguration, modification and expansion. Human users may dynamically change the IFish in response to changes in the environment, or IFish may initiate such changes itself. IFish maintain internal state, including models of its own structure, behavior, information environment and its user; these models permit an IFish to perform meta-level reasoning about its own structure. To facilitate rapid assembly of particular IFish I have created the Internet Fish Construction Kit. This system provides enabling technology for the entire class of Internet Fish tools; it facilitates both creation of new IFish as well as additions of new capabilities to existing ones. The Construction Kit includes a collection of encapsulated heuristic knowledge modules that may be combined in mix-and-match fashion to create a particular IFish; interfaces to new services written with the Construction Kit may be immediately added to "live" IFish. Using the Construction Kit I have created a demonstration IFish specialized for finding World-Wide Web documents related to a given group of documents. This "Finder" IFish includes heuristics that describe how to interact with the Web in general, explain how to take advantage of various public indexes and classification schemes, and provide a method for discovering similarity relationships among documents.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Caracteristicas principais dos dejetos; Principais técnicas de tratamento dos dejetos; Tratamento de dejetos nas pequenas e grandes propriedades produtoras de suínos; Técnicas de valorização dos dejetos suínos e seus produtos; Controle integrado de moscas nas criações de suínos; Técnicas construtivas em edificações para o aproveitamento dos dejetos.