9,980 research outputs found
Single-molecule studies of unconventional motor protein myosin VI
No full textMyosin VI is one of the myosin superfamily members that are actin-based molecular motors. It has received special attention due to its distinct features as compared to other myosins, such as its opposite directionality and a much larger step size than expected given the length of its “leg”.
This dissertation presents the author‟s graduate work of several single-molecule studies on myosin VI. Special attention was paid to some of myosin VI‟s tail domains that consist of proximal tail (PT), medial tail (MT), distal tail (DT) domains and cargo-binding domain (CBD).
The functional form of myosin VI in cells is still under debate. Although full length myosin VI proteins in cytosolic extracts of cells were monomers from earlier studies, there are several reasons why it is now believed that myosin VI could exist as a dimer. If this is true and dimerization occurs, the next logical question would be which parts of myosin VI are dimerization regions? One model claimed that the CBD is the sole dimerization region. A competing model claimed that there must be another region that could be involved in dimerization, based on their observation that a construct without the CBD could still dimerize.
Our single-molecule experiment with progressively truncated myosin VI constructs showed that the MT domain is a dimerization region, supporting the latter model. Additional single-molecule experiments and molecular dynamics (MD) simulation done with our collaborators suggest that electrostatic salt bridges formed between positive and negative amino acid residues are mainly responsible for the MT domain dimerization.
After resolving this, we are left with another important question which is how myosin VI can take such a large step. Recent crystal structure showed that one of the tail domains preceding the MT domain, called the PT domain, is a three-helix bundle. The most easily conceivable way might be an unfolding of the three-helix bundle upon dimerization, allowing the protein to stretch and reach a larger distance. The single-molecule stepping data with mutant full-length construct that lacks two helices out of three in the PT domain tell that it is indeed the case.
In this dissertation, more details of myosin VI PT/MT domain experiments will be explored along with background information on the single-molecule experiment methods used in these studies.Item withdrawn by Mark Zulauf ([email protected]) on 2011-04-07T13:00:38Z
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Bending dynamics of semi-flexible particles in turbulent flows
No full textWe study the Lagrangian dynamics of semi-flexible particles in laminar as well as in homogeneous and isotropic turbulent flows by means of analytically solvable stochastic models and direct numerical simulations. The statistics of the bending angle is qualitatively different in laminar and turbulent flows and exhibits a strong dependence on the topology of the velocity field. In particular, in two-dimensional turbulence, particles are either found in a fully extended or in a fully folded configuration; in three dimensions, the predominant configuration is the fully extended one
Oxidation of ciprofloxacin and enrofloxacin by ferrate(VI): Products identification, and toxicity evaluation
No full textFerrate(VI) (Fe(VI)) has been known to react with emerging organic contaminants containing electron rich organic moieties, such as phenols, anilines, olefins, reduced sulfur and deprotonated amines. Oxidation of fluoroquinolone antibiotics, ciprofloxacin (CIP) and enrofloxacin (ENR), by Fe(VI) were investigated for their reaction products and toxicity changes as well as biodegradability of these products. Ten products were identified for both CIP and ENR reactions with Fe(VI) using a high-resolution accurate-mass Orbitrap mass analyzer. Structural changes to the CIP and ENR molecule included dealkylation, formation of alcohols and amides in piperazine ring and oxygen transfer to the double bond in quinolone structure. An enamine formation mechanism was tentatively proposed to facilitate the interpretation of CIP and ENR oxidation pathways. Toxicity evaluation using Microbial Assay for toxicity Risk Assessment (MARA) bioassay indicated that Fe(VI) oxidation products of CIP and ENR contributed negligible antibacterial potency and Fe(VI) oxidation treatment can remove the residual toxicity of CIP and ENR impacted source waters. The Fe(VI) oxidation treatment resulted in formation of relatively more biodegradable products (based on in silico assessment) than their corresponding parent compounds. The results showed that Fe(VI) has a good potential to degrade fluoroquinolone antibiotics and their antimicrobial potency in natural waters. (C) 2016 Elsevier B.V. All rights reserved
Vi Kowalchuk
No full textPhotograph - Vi Kowalchuk, member of the Book Sub-Committee, part of the Town of Athabasca 75th Anniversary Committee, Athabasca, Alberta. The Book Sub Committee produced the book "Athabasca Landing: An Illustrated History
Cr(VI) and Cr(III)-Based Conversion Coatings on Zinc
No full textWith the aims of understanding the protective mechanism of chromate conversion coatings and developing alternatives to chromate treatments, the physical natures and corrosion properties of Cr(VI) and Cr(III) treated zinc have been investigated in this work. The Cr(VI) treatments were carried out in dichromate and sulfuric acid solution with different dipping times. The Cr(III) treatments were carried out in two commercial solutions (A and B). The thickness of the coatings was measured using ellipsometry. The morphologies and the compositions of the treated zinc have been studied by means of SEM, AFM, AES, FTIR and XPS. The drying temperature influence on the corrosion performance of the Cr(VI)âtreated zinc has been investigated. The Volta potential in treated and untreated areas has been measured using scanning Kelvin probe (SKP) and SKPFM. The corrosion behavior of the Cr(VI) and Cr(III) treated zinc has been investigated using polarization, electrochemical impedance measurements (EIS), and salt spray tests. Both Cr(VI) and Cr(III) species were detected by XPS in the outermost layer of the Cr(VI) coatings, while no Cr(VI) species was found in the Cr(III) coatings. AES depth profile results show that chromium oxides are the main components in the Cr(VI) coatings. Zinc oxide is mainly located at the chromium oxides / zinc interface. The Cr(III) coating is a mixture of chromium oxides and zinc oxide. Both the Cr(VI) and the Cr(III) treatments can supply corrosion protection to zinc. The corrosion resistance of the Cr(III)-B coating is greater than that of the Cr(III)-A coating. However, the inhibition of the corrosion of zinc by Cr(VI) coating is more effective than by the Cr(III) coatings. The inhibition of the corrosion of zinc by the Cr(VI) and the Cr(III) treatments is discussed, and future research topics are suggested.Mechanical, Maritime and Materials Engineerin
Introduction - Part VI: Eugenics
No full textBook synopsis: Sexology Uncensored brings together, for the first time, many of the key documents of the modern science of sexuality that emerged in the late nineteenth century. The early pioneers of the new field of sexology examined and classified sexual behaviours, identities and relations. For years much of the material here has been "censored" - difficult to obtain, subject to restrictive circulation, or available only in medical archives. This volume offers readers access to the primary materials on which contemporary sexology is founded and, as such, it is an invaluable record for all those interested in how we have come to think about sex and sexuality over the last one hundred years.
The extracts in Sociology Uncensored (which date from the 1880s to the 1940s) are organized thematically: gender and sexual difference; homosexualities; transsexuality and bisexuality; heterosexuality; marriage and sex manuals; reproductive control; eugenics; race; and other sexual proclivities.
This book will be essential reading for researchers, teachers and students interested in the history and study of sex and of great interest to the general reader
Xây dựng thang đo hành vi công dân tổ chức của nhân viên trong ngành khách sạn theo mô hình 3 chân (a three-leg model)
No full textIn the hospitality industry, the job characteristics of frontline employees are distinctively characterized by high levels of interaction while serving customers. In addition to organizational citizenship behavior directed towards colleagues and the organization, organizational citizenship behavior oriented towards customers significantly enhances positive customer experiences, which is a core factor contributing to the enterprise’s success. This study applies a three-leg model to develop a scale for measuring employees’ organizational citizenship behavior directly serving customers in the Danang City, Vietnam, hotel industry. The author employs a qualitative research method to gain deeper insights into the scale; subsequently, quantitative research is utilized to evaluate the scale. The research findings indicate that the three-leg model achieves a high level of compatibility, wherein the organizational citizenship behavior of hotel employees can be measured through 18 observed variables across three aspects: organizational citizenship behavior directed towards the organization (06 items), organizational citizenship behavior directed towards colleagues (06 items), and organizational citizenship behavior directed towards customers (06 items).Với ngành khách sạn, đặc điểm công việc của nhân viên tuyến đầu mang tính riêng biệt bởi dịch vụ đòi hỏi từ sự tương tác cao giữa khách hàng và nhân viên. Bên cạnh hành vi công dân tổ chức hướng đến đồng nghiệp và tổ chức, hành vi công dân tổ chức hướng đến khách hàng có ảnh hưởng đáng kể đến việc nâng cao trải nghiệm tích cực của khách hàng, là nhân tố cốt lõi đem lại hình ảnh thương hiệu cho khách sạn. Nghiên cứu này vận dụng mô hình 3 chân (a three-leg model) để xây dựng thang đo hành vi công dân tổ chức của nhân viên trong bối cảnh ngành khách sạn tại thành phố Đà Nẵng, Việt Nam. Để có những hiểu biết rõ ràng và thấu đáo hơn về thang đo, tác giả sử dụng phương pháp nghiên cứu định tính; tiếp theo, sử dụng nghiên cứu định lượng nhằm đánh giá thang đo. Kết quả nghiên cứu cho thấy mô hình 3 chân đạt được sự tương thích cao, trong đó hành vi công dân tổ chức của nhân viên trong ngành khách sạn có thể đo lường qua 18 mục hỏi ở 03 khía cạnh là hành vi công dân tổ chức hướng đến tổ chức (06 mục hỏi), hành vi công dân tổ chức hướng đến đồng nghiệp (06 mục hỏi) và hành vi công dân tổ chức hướng đến khách hàng (06 mục hỏi)
Profiles of parabens and triclocarban in recirculating aquaculture systems : An analytic method of development
No full textOrganic substances can be released from numerous sources such as feed, waste, bacteria and fish in a recirculating aquaculture system (RAS). Compounds can start accumulating in the system and affect the quality of water negatively due to the fact that the water is re-used continuously. In RAS systems, the input is water from natural sources, and it will be recycled through different treatment stations and instruments to control hygiene and dis-eases as well as biological pollution. This project analyzed feed and waste samples taken from a recirculating aquaculture system (RAS) in order to determine the presence of the target chemicals (six parabens, five parabens derivatives and antimicrobial).
The samples were collected at the Nofima Center for Recirculation in Aquaculture (NCRA) in Sunndalsøra, Norway. After that, samples were processed with numerous methods and techniques for extracting the target chemicals such as solid phase extraction (SPE) and liquid-liquid extraction (LLE). Then, the samples were analyzed by using liquid chromatog-raphy – tandem mass spectrometry (LC-MS/MS)
A Case Study of Public Private Partnership in the Construction Sector in Ho Chi Minh City, Vietnam
No full textPublic Private Partnership PPPs in developed countries exhibit a successful strategy along with the framework that while appealing the private sector, the role for state in
ensuring that social responsibilities have been met and successful sector reforms and public investment achieved. PPPs depicts a number of recognized benefits for the
public sector to exploit especially in terms of benefiting the public infrastructure. This also caters the aptitude to promote the additional finance in an environment of
budgetary restrictions, also ensure the effective use of private sector operational efficiencies for reducing the cost and further to increase the quality of services
provided to the public and the ability to speed up infrastructure development. The purposes of this study are to assess the existing conditions that are enabling and disenabling the applying of PPP arrangement infrastructure in Ho Chi Minh city with focusing on legal, regulatory, and policy framework, institutional framework, technical issues, investment and socioeconomic issues, stakeholders consultation, financing requirements, risk management and managing the interface between public and private partners, to identify key factors for influencing successful Public-Private Partnerships in infrastructure projects and the constraints and up to now the features of a good relationship management of PPP projects. The findings show the lack of readiness of infrastructure sector for implementing large-scale PPP projects and the study recommended according to analysis that the state should take actions for enabling a successful PPP in infrastructure and mitigating the gap which is required for PPP project’s development and implementation. The important steps are establishing a sound of legal and institutional framework, develop policies and guidelines, creating a stable environment and conducive to investment with the aim of encouraging private sector investments in the water and wastewater sector, developing a strategic framework for relationship management of PPP projects to enable both public and private sectors to manage these important PPP relationships successfully. There was the total of 150 questionnaires were sent out, and the total of 400 valid answer was obtained for data analysis tool. As major successful ingredients to be indicated to the most crucial factor for evaluating the public and private sectors. Moreover, the effectiveness related to the cost and also the financial attraction have been taken as highly recognised evaluation factors which could ranked by the public sector and private consortium respectively. In addition, the “existence of a long-term demand for the proposed services”, further availability of “strong private consortium”, alignment with state’s “strategic objectives”, as well as reliable “service delivery” need to be rated as highly important to the success of PPP schemes. On the other side, the tripartite expectations need to be ensured as indispensable for making the feasibility and successful delivery of public services and infrastructure projects via PPP scheme in Ho Chi Minh City in infrastructure projects. This study enables international and domestic construction companies to better understand how success and constraints should be assessed and allocated for PPP project in Ho Chi Minh City in infrastructure. It also assists in constraints and success response planning and control for future PPP projects in Ho Chi Minh City in infrastructure projects
INTEGRATION OF METAHEURISTIC TECHNIQUE IN THERMO-ELECTRIC COOLING DEVICE TO ENHANCE EFFICIENCY AND PERFORMANCE
No full textThermo-electric Cooler (TEC) nowadays is applied in a wide range of thermal
energy systems. This is due to its superior features where no refrigerant and dynamic
parts are needed. TEC generates no electrical or acoustical noise and are environment
friendly. Over the past decades, many researches were employed to improve the
efficiency of TEC by enhancing the material parameters and design parameters. The
material parameters are the most significant, but they are restricted by currently
available materials and module fabricating technologies. Therefore, the main
objective of TEC design is to determine a set of design parameters which can enhance
its performance. Two elements that play an important role when considering the
suitability of TEC in applications are cooling rate and coefficient of performance
(COP). In this research, the technical issues of single-stage TEC and two-stage TEC
are discussed
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