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101.
1. Several ring-substituted derivatives of diphenyleneiodonium catalyse the exchange of Cl- and OH- ions across the inner membrane of rat liver mitochondria. They also inhibit state 3 and state 3u oxidations of glutamate plus malate in the presence of Cl- more than in its absence. Most have activities similar to diphenyleneiodonium, although 2,4-dichlorodiphenyleneiodonium is up to 50 times more active. 2. Diphenyleneiodonium inhibits soluble rat liver NADH dehydrogenase and NADH oxidation by rat liver sub-mitochondrial particles directly; 2,4-dichlorodiphenyleneiodonium is only about twice as inhibitory. 3. Liver mitochondria contain two classes of binding sites for diphenylene[125I]iodonium, namely high-affinity sites with an affinity constant of 3 X 10(5) M-1 (1--2 nmol/mg of protein), and low-affinity sites with an affinity constant of 1.3 X 10(3) M-1 (80 nmol/mg of protein). Both sites occur in hepatocytes with a relative enrichment of the low-affinity site. Nadh dehydrogenase preparations only apparently contain high-affinity binding sites. Only low-affinity sites occur in erythrocytes. 4. 2,4-Dichlorodiphenyleneiodonium competes with diphenylene[125I]iodonium for both low- and high-affinity sites, whereas tri-n-propyltin only competes for the low-affinity sites. 5. The high-affinity sites are apparently associated with NADH dehydrogenase and the low-affinity sites probably represent electrostatic binding of diphenylene[125I]iodonium to phospholipids. The high-affinity site does not appear to be associated with a rate-limiting stage of NADH oxidation. 相似文献
102.
Oil-in-water (o/w) emulsions for cosmetic use, such as lotions and creams, are complex multiple-phase systems, which may contain a number of interacting surfactants, fatty amphiphiles, polymers and other excipients. This study investigates the influence of two synthetic cationic polymers, Polyquaternium-7 and Polyquaternium-11, and the natural anionic polymer, gum of acacia, on the rheology and microstructure of creams prepared with a non-ionic mixed emulsifier (cetyl stearyl alcohol-12EO/cetyl alcohol) using rheology (continuous shear, and viscoelastic creep and oscillation), microscopy and differential scanning calorimetry (DSC). A control cream containing no polymer was also investigated. The semisolid control cream was structured by a swollen lamellar gel network phase formed from the interaction of cetyl alcohol and the POE surfactant, in excess of that required to stabilize oil droplets, with continuous phase water. Endothermic transitions between 25 and 100 degrees C were identified as components of this phase. Incorporation of cationic polymer into the formulation caused significant loss of structure to produce a mobile semisolid containing larger oil droplets. The microscopical and thermal data implied that the cationic polymer caused the swollen lamellar gel network phase to transform into non-swollen crystals of cetyl alcohol. In contrast, incorporation of gum of acacia produced a thicker cream than the control, with smaller droplet sizes and little evidence of the gel network. Microscopical and thermal data implied that although there were also interactions between gum of acacia and both the surfactant and the swollen gel network phase, the semisolid properties were probably because of the ability of the gum of acacia to stabilize and thicken the emulsion in the absence of the swollen lamellar network. 相似文献
103.
A.J.?Mendes?FerreiraEmail author M.C.S.?Ribeiro A.?Torres?Marques 《International Journal of Mechanics and Materials in Design》2004,1(2):143-155
In this paper, a numerical approach for the analysis of a new type of hybrid composite beams is presented. Such beams are composed of composite materials that resist shear and tensile stresses, and polymer concrete acommodating compression stresses.The beams offer an optimized configuration in terms of stiffness and strength, with much potential for mechanical and civil engineering structures.The current numerical model is based on a finite element formulation for layered shell-like structures. The model accounts for a polymer concrete material model, orthotropic material model, and considers the analysis of geometric and material nonlinearities. The first-order shear deformation theory is used in order to describe the shell deformation under a total Lagrangian formulation. The model is validated experimentally and a close agreement with experimental results makes this model an attractive solution method for this type of composite hybrid beams. 相似文献
104.
The conversion of [14C]arginine into [14C]citrulline as an indicator of nitric oxide synthesis was studied in uteri isolated from rats on different days of gestation, after labour and during dioestrus. Nitric oxide synthesis was present in uterine tissues isolated at each stage of gestation and also in tissues collected during dioestrus and after labour. Expression of neuronal nitric oxide synthase was not detectable at any of the stages studied. Endothelial nitric oxide synthase was present at all the stages studied, but there was a significant increase on day 13 of gestation and a decrease thereafter, with the lowest expression recorded on the day after labour. Inducible nitric oxide synthase expression in rat uteri increased substantially during pregnancy, with the highest expression on day 13 of gestation; expression decreased at term and after labour. The changes in expression of inducible nitric oxide synthase were coincident with the changes in nitric oxide synthase activity in uteri treated with aminoguanidine. Thus, these findings indicate that an increase in expression of inducible nitric oxide synthase in the uterus may be important for maintenance of uterine quiescence during pregnancy and its decrease near the time of labour could have an effect on the start of uterine contractility. 相似文献
105.
Catarina Silva Bernardete Ribeiro 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2007,11(6):519-530
Text mining, intelligent text analysis, text data mining and knowledge-discovery in text are generally used aliases to the
process of extracting relevant and non-trivial information from text. Some crucial issues arise when trying to solve this
problem, such as document representation and deficit of labeled data. This paper addresses these problems by introducing information
from unlabeled documents in the training set, using the support vector machine (SVM) separating margin as the differentiating
factor. Besides studying the influence of several pre-processing methods and concluding on their relative significance, we
also evaluate the benefits of introducing background knowledge in a SVM text classifier. We further evaluate the possibility
of actively learning and propose a method for successfully combining background knowledge and active learning. Experimental
results show that the proposed techniques, when used alone or combined, present a considerable improvement in classification
performance, even when small labeled training sets are available. 相似文献
106.
This paper presents a parallel implementation of the finite element method designed for coarse-grain distributed memory architectures.
The MPI standard is used for message passing and tests are run on a PC cluster and on an SGI Altix 350. Compressed data structures
are employed to store the coefficient matrix and obtain iterative solutions, based on Krylov methods, in a subdomain-by-subdomain
approach. Two mesh partitioning schemes are compared: non-overlapping and overlapping. The pros and cons of these partitioning
methods are discussed. Numerical examples of symmetric and non-symmetric problems in two and three dimensions are presented. 相似文献
107.
In this paper, we derive an estimation method that jointly estimates the parameters of the concentrated propagation paths and the distributed scattering component that are frequently observed in multiple-input multiple-output (MIMO) channel sounding measurements. The joint angular-delay domain model leads to a correlation matrix with high dimensionality, which makes direct implementation of a maximum-likelihood (ML) estimator unfeasible. We derive low-complexity methods for computing approximate ML estimates that exploit the structure of the covariance matrices. We propose an iterative two-step procedure that alternates between the estimation of the parameters of the concentrated propagation paths and the parameters of the distributed scattering. For the distributed scattering, the estimator first optimizes the parameters describing their time-delay structure. Then, using the estimated time-delay parameters, the parameters of the angular distributions are optimized. We present simulation results and compare the estimated time-delay and angular distributions to the actual distributions, demonstrating that high-quality estimates are obtained. The large sample performance of the estimator is studied by establishing the Cramer-Rao lower bound (CRLB) and comparing it to the variances of the estimates. The simulations show that the variance of the proposed estimation technique reaches the CRLB for relatively small sample size for most parameters, and no bias is observed. 相似文献
108.
Microglia Response and In Vivo Therapeutic Potential of Methylprednisolone‐Loaded Dendrimer Nanoparticles in Spinal Cord Injury
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109.
New iron(III) extraction data involving two N,N-disubstituted monoamides, N-ethyl-N-phenyloctanamide (EPHOA) and N-ethyl-N-cyclohexyloctanamide (ECHOA), from hydrochloric acid media, are presented and discussed. These, and earlier results obtained with other similar N,N-disubstituted monoamides, are interpreted in this work through their apparent molar volumes in 1,2-dichloroethane, and all the information is being used to screen for solute-solute and solute-diluent interactions. The results collected help to understand why N-cyclohexyl monoamides are generally more efficient than their N-phenyl analogues as liquid-liquid extractants for iron(III) from 3 to 5 M hydrochloric acid solutions, and clearly denote that N-phenyl monoamides are essentially monomeric whereas N-cyclohexyl monoamide derivatives have a tendency to aggregate in the organic solution. 相似文献
110.
Equilibrium data for carbon dioxide and methane adsorption on nanoporous metal organic framework Cu‐BTC powder and tablets were measured in a magnetic suspension balance in the temperature range of 308–373 K and a pressure range of 0–7 bar and fitted with Langmuir model. The tablets adsorption loading is 0.63 mol kg–1 for methane and 3.1 mol kg–1 for carbon dioxide at 1 bar and 308 K, while these values are 0.77 and 3.9 mol kg–1 for powder in the same conditions. Isosteric heats of adsorption were 22.8 and 15.0 kJ mol–1 for carbon dioxide and methane, respectively, on both adsorbents, which indicates a strong adsorption of carbon dioxide. Also, single and binary breakthrough curves were measured in the same temperature range and atmospheric pressure by using Cu‐BTC tablets as adsorbent. A complete model was used in the simulation of breakthrough curves and good agreement was observed with experimental data. 相似文献