324 research outputs found

    Proton Magnetic Relaxation in Ethane Diol-Water Solutions of Haemoglobin

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    Ethane diol was added to aqueous solutions of bovine and human met(FeUI)- and CO-haemoglobin in order to extend the temperature range for nuclear magnetict relaxation measurements below freezing point. No significant difference in the relaxation rates was found on adding ethane diol except in the case of human met- and CO-haemog1obin, which may be . ascribed to chang·es in the hydration sheath. The energies of activation derived :firom Arrhenius plots of the relaxation rates for bovine Hb are also independent (within ± 50/o) of ethane diol. It is concluded that the gross conformation of the haem pocket is not altered by addition of ethane diol, so that measurements can be done down to - 30 °c

    Impact of family in-home quality time on person travel demand

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    This paper introduces the concept of Primary Family Priority Time (PFPT), which represents a high priority household decision to spend time together for in-home activities. PFPT is incorporated into a fully specified and operational activity based (AB) discrete choice model system for Copenhagen, called COMPAS, using the DaySim software platform. Structural tests and estimation results identify two important findings. First, PFPT belongs high in the model hierarchy, and second, strong interactions exist between PFPT and the other day level activity components of the model system. Forecasts are generated for a road pricing and congestion scenario by COMPAS and a comparison version of the model system that excludes PFPT. COMPAS with PFPT exhibits less mode changing and time-of-day shifting in response to pricing and congestion than the comparison version

    Enzymatic Processing of Amelogenin during Continuous Crystallization of Apatite

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    Dental enamel forms through a protein-controlled mineralization and enzymatic degradation with a nanoscale precision that new engineering technologies may be able to mimic. Recombinant fulllength human amelogenin (rH174) and a matrix-metalloprotease (MMP-20) were employed in a pHstat titration system that enabled a continuous supply of calcium and phosphate ions over several days, mimicking the initial stages of matrix processing and crystallization in enamel in-vitro. Effects on the self-assembly and crystal growth from a saturated aqueous solution containing 0.4 mg/ml rH174 and MMP-20 with the weight ratio of 1:1000 with respect to rH174 were investigated. A transition from nanospheres to fibrous amelogenin assemblies was facilitated under conditions that involved an interaction between rH174 and the proteolytic cleavage products. Despite continuous titration, the levels of calcium exhibited a consistent trend of decreasing, thereby indicating its possible role in the protein self-assembly. This study suggests that mimicking enamel formation in-vitro requires the synergy between the aspects of matrix self-assembly, proteolysis and crystallization

    Aspekt promene geometrije pri dejstvu koncentrisane sile u projektovanju montažnih membranskih konstrukcija

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    Point loads can act on membrane structures; nevertheless, they are rarely checked in the structural analysis. This is a consequence of the fact that there are no precise instructions that would oblige and direct membrane structures designers how to conduct this analysis. The work to create Eurocode for the Structural Design of Tensile Membrane Structures is underway. When this standard comes into force, it will require following Eurocode 1 with regard to actions on membrane structures. This means that point loads will be included in this structural analysis. However, the consequences of point load actions have yet to be investigated. The subject of this doctoral dissertation research is the change of geometry of membrane structures under point load action. The research for this doctoral dissertation is conducted by testing numerical models of membrane structures in software package Sofistik 2016. Parametric analysis is used to find out how much and in which way varying the values of selected parameters changes the geometry of membrane structures under point load action. Nine parameters divided into groups of those which are related to load, membrane material and the supports have been analyzed. A large number of models differing by parameter values has been created. The goal of the research is to find out how the change of values of analyzed parameters affects the changes of geometry, how big is the influence of these parameters, and what is the importance of point loads for changes of geometry of membrane structures. Based on the obtained results, the dependence of changes of geometry under point load on the analized parameters is determined. The results of the research show that the point load can cause larger changes of geometry compared to the area load whose value is taken to be the usual snow load. Since the point load actions are currently almost completely neglected, this result was not expected. Based on this, it can be concluded that the point load actions are very significant, and that it is necessary to further continue the research of point load action on membrane structures

    Amoxicillin Biodegradation with Bacillus subtilis and Pseudomonas aeruginosa: Characterization of Relevant Degradation Products

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    The widespread use of antibiotics can result in the release of a large number of residues into the environment. In order to reduce the exposure risk, considerable research has been carried out in the field of antibiotic residues. We aim to explore the possibilities of antibiotic amoxicillin biodegradation in laboratory scale by adding microbiological cultures, Pseudomonas aeruginosa (Gram-negative) and Bacillus subtilis (Gram-positive), which are a type of bacteria that are commonly found in the environment, such as in soil and water. Apart from the degradation itself, special attention was paid to the identification of antibiotic residues. The biodegradation process was investigated, revealing a 99.2 % degradation efficiency at amoxicillin concentration of 0.2 mg mL–1, and four degradation products were identified. For reaction monitoring and identification of degradation products, UHPLC and LC-MS analyses were performed. Furthermore, to provide additional evidence, the products were independently synthesized and then compared spectrometrically with the obtained biodegradation products. These results could provide new aspects to the behavior of amoxicillin, and pave the way for further monitoring and studies of its residues in the environment. This work is licensed under a Creative Commons Attribution 4.0 International License

    Uncanny Valleys in Declarative Language Design

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    When people write programs in conventional programming languages, they over-specify how to solve the problem they have in mind. Over-specification prevents the language\u27s implementation from making many optimization decisions, leaving programmers with this burden. In more declarative languages, programmers over-specify less, enabling the implementation to make more choices for them. As these decisions improve, programmers shift more attention from implementation to their real problems. This process easily overshoots. When under-specified programs almost always work well enough, programmers rarely need to think about implementation details. As their understanding of implementation choices atrophies, the controls provided so they can override these decisions become obscure. Our declarative language project, Yedalog, is in the midst of this dilemma. The improvements in question make our users more productive, so we cannot simply retreat back towards over-specification. To proceed forward instead, we must meet some of the expectations we prematurely provoked, and our implementation\u27s behavior must help users learn expectations more aligned with our intended semantics. These are general issues. Discussing their concrete manifestation in Yedalog should help other declarative systems that come to face these issues

    Hepatic Cytochrome P-450. A Proton Magnetic Relaxation Study of Microsomal, Solubilized and Partially Reconstituted Enzyme System

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    The longitudiJ:ial proton magnetic relaxation times, Ti, were measured from -5 to 40 °c for microsomal, solubilized and reconstituted cytochrome P-450 obtained from phenobarbital-induced rat livers. The paramagnetic contribution to the rates was derived by subtraction of the rates measured on dithionite-CO-reduced samples. The same values were obtained for microsomal P-450 on reduction with NADPH. PMR titratio.n by KCN yielded a dissociation constant of about 30 mM. This is three orders of magnitude larger than for metmyoglobin. It is concluded that the measured PMR rates are most likely due to the P-450 (and P-420) haem-iron while the 300/o non-haem iron found in both the microsomal and s olubilized P-450 is .ineffective for the PMR rates. These rates increase several times on isotopic dilution (D20 for H20) with the microsomes and diminish for the solubilized samples. Microsomes show 170/o residual, encaged, H20. Most of their paramagnetic PMR rate is due to the parama.gnetic iron located on the outside of microsomes. This is demonstrated by measurements with deuterated samples to which 190/o H20 had been added. Hence, the solubilized P-450 is homogeneous regarding PMR, but the microsomes are not
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