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Ki
Terms modified by Ki Selected AbstractsFracture behaviour of PC/ABS resin under mixed-mode loadingFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 12 2001Husaini Fracture behaviour of polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) under mixed-mode loading conditions was studied for several weight fractions of PC and ABS. Mode I and mixed-mode fracture tests were carried out by using compact,tension,shear specimens. At a certain value of mixed-mode loading ratio KII,/KI, a crack of the shear type will initiates at the initial crack tip. Fracture toughness increases under mixed-mode loading with an increase in the mode II component, whereas it reduces with the appearance of a shear-type fracture. Fracture toughness and the appearance of a shear-type fracture depends on the blending ratio of PC and ABS. The transition to shear-type fracture occurs at lower value of KII,/KI for resins with higher fracture toughness. [source] Toxicity assessment of mono-substituted benzenes and phenols using a Pseudomonas initial oxygen uptake assayENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2005Ded-Shih Huang Abstract A methodology is presented for assessing the toxicity of chemical substances through their inhibitory action toward the Pseudomonas initial oxygen uptake (PIOU) rate. The current studies reveal that the PIOU assay is rapid, cost-efficient, and easy to perform. The oxygen uptake rate was found to be associated with a putative benzoate transporter and highly dependent on benzoate concentration. The putative benzoate transporter has been shown to follow Michaelis,Menten kinetics. Most phenols were found to be noncompetitive inhibitors of the benzoate transporter. The inhibition constant (Ki) of these noncompetitive inhibitors can be related to the concentration causing 50% oxygen uptake inhibition in Pseudomonas putida. Modeling these data by using the response,surface approach leads to the development of a quantitative structure,activity relationship (QSAR) for the toxicity of phenols ((1/Ki) = ,0.435 (±0.038) lowest-unoccupied-molecular orbital + 0.517 (±0.027)log KOW ,2.340 (±0.068), n = 49, r2 = 0.930, s = 0.107, r2adj = 0.926, F = 303.1). A comparison of QSAR models derived from the Ki data of the PIOU method and the toxicity data of 40-h Tetrahymena pyrifomis growth inhibition assay (Tetratox) indicated that there was a high correlation between the two approaches (r2 = 0.925). [source] Correlation between the predicted and the observed biological activity of the symmetric and nonsymmetric cyclic urea derivatives used as HIV-1 protease inhibitors.JOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 3 2003A 3D-QSAR-CoMFA method for new antiviral drug design Abstract The predicted inhibition constant (Ki) and the predicted inhibitor concentration (IC90) of the HIV-1 protease (HIV-1 PR) inhibitors: symmetric and nonsymmetric - benzyl, ketone, oxime, pyrazole, imidazole, and triazole cyclic urea derivatives, were obtained by the 3D-CoMFA (Comparative Molecular Field Analysis) method. The CoMFA statistical parameters: cross-validate correlation coefficient (q2), higher than 0.5, and the fitted correlation coefficient (r2), higher than 0.90 validated the predicted biological activities. The best predictions were found for the trifluoromethyl ketoxime derivative (log 1/Ki predict = 8.42), the m-pyridineCH2 pyrazole derivative (log 1/Ki predict = 9.77) and the 1,2,3 triazole derivative (log 1/Ki predict = 7.03). We attempted to design a new potent HIV-1 protease inhibitor by addition of o-benzyl to the (p-HOPhCH2) pyrazole 12f derivative inhibitor. A favorable steric area surrounded the o-benzyl, suggesting a possible new potent HIV-1 protease inhibitor. [source] Amphiphilic Homochiral Oligopeptides Generated via Phase Separation of Nonracemic , -Amino Acid Derivatives and Lattice-Controlled Polycondensation in a Phospholipid EnvironmentHELVETICA CHIMICA ACTA, Issue 11 2003Irina Rubinstein Racemic S -ethyl thioesters of N, -stearoyllysine (=,S -ethyl (R,S)-2-amino-6-(stearoylamino)hexanethioate) and S -ethyl thioesters of , -stearyl glutamic acid (=stearyl (R,S)-4-amino-5-(ethylsulfanyl)-5-oxopentanoate) self-assemble as separated two-dimensional crystalline monolayers within an achiral phospholipid environment of racemic 1,2-dipalmitoylglycerol (DPG) and 1,2-dipalmitoylglycero-3-phosphoethanolamine (DPPE), as demonstrated by grazing-incidence X-ray-diffraction (GIXD) measurements performed on the surface of H2O. Lattice-controlled polycondensation within these crystallites with deuterium-enantiolabeled monomers was initiated by injecting aqueous solutions of Ag+ or I2/KI beneath the monolayers, which yielded mixtures of diastereoisomeric oligopeptides containing up to six to eight repeating units, as analyzed by MALDI-TOF mass spectrometry. Analysis of the diastereoisomeric distribution showed an enhanced relative abundance of the oligopeptides with homochiral sequences containing three or more repeating units. Within the DPPE monolayers, the nucleophilic amino group of the phospholipid operates as an initiator of polymerization at the periphery of the monomer two-dimensional crystallites. Enhanced relative abundance of enantiomerically enriched homochiral oligopeptides was obtained by the polycondensation of nonracemic monomers. This enhancement indicated a phase separation into racemic and enantiomorphous monomer crystallites within the phospholipid environment, although this separation could not be observed directly by GIXD. A possible role that might have been played by crystalline assemblies for the abiotic generation and amplification of oligopeptides with homochiral sequences is discussed. [source] Studies on multiphased mixed crystals of NaCl, KCl and KICRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2009M. Priya Abstract Multiphased mixed crystals of NaCl, KCl and KI were grown by the melt method, for the first time. Densities and refractive indices of all the grown crystals were determined and used for the estimation of the composition in the crystal. Atomic absorption spectroscopic measurements were done to estimate the metal atom contents in the crystal. Lattice parameters and thermal parameters (Debye-Waller factor, mean square amplitude of vibration, Debye temperature and Debye frequency) were determined from the X-ray powder diffraction data. DC and AC electrical measurements were done at various temperatures ranging from 40 to 150°C. Activation energies were also estimated. The observed lattice parameters showed that the system exhibits three phases each nearly corresponds to NaCl, KCl and KI. The thermal and electrical parameters show a highly nonlinear bulk composition dependence. Results are reported. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The effect of foundation embedment on inelastic response of structuresEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 4 2009Mojtaba Mahsuli Abstract In this research, a parametric study is carried out on the effect of soil,structure interaction on the ductility and strength demand of buildings with embedded foundation. Both kinematic interaction (KI) and inertial interaction effects are considered. The sub-structure method is used in which the structure is modeled by a simplified single degree of freedom system with idealized bilinear behavior. Besides, the soil sub-structure is considered as a homogeneous half-space and is modeled by a discrete model based on the concept of cone models. The foundation is modeled as a rigid cylinder embedded in the soil with different embedment ratios. The soil,structure system is then analyzed subjected to a suit of 24 selected accelerograms recorded on alluvium deposits. An extensive parametric study is performed for a wide range of the introduced non-dimensional key parameters, which control the problem. It is concluded that foundation embedment may increase the structural demands for slender buildings especially for the case of relatively soft soils. However, the increase in ductility demands may not be significant for shallow foundations with embedment depth to radius of foundation ratios up to one. Comparing the results with and without inclusion of KI reveals that the rocking input motion due to KI plays the main role in this phenomenon. Copyright © 2008 John Wiley & Sons, Ltd. [source] A chip-based miniaturized format for protein-expression profiling: The exploitation of comprehensively produced antibodiesELECTROPHORESIS, Issue 18 2006Hisashi Koga Dr. Abstract Numerous antibodies have been developed and validated in recent years, and show promise for use in novel functional protein assays. Such assays would be an alternative to pre-existing comprehensive assays, such as DNA microarrays. Antibody microarrays are thought to represent those functional protein assays. While a variety of attempts have been made to apply DNA microarray technology to antibody microarrays, a fully optimized protocol has not been established. We have been conducting a project to comprehensively produce antibodies against mouse KIAA ("KI" stands for "Kazusa DNA Research Institute" and "AA" are reference characters) proteins. Using our library of antibodies, we established a novel antibody microarray format that utilizes surface plasmon resonance (SPR) technology. A label-free real-time measurement of protein expression in crude cell lysates was achieved by direct readout of the bindings using SPR. Further refinement of the antibody microarray format enabled us to detect a smaller quantity of target proteins in the lysate without the bulk effect. In this review, we first summarize available antibody array formats and then describe the above-mentioned format utilizing updated SPR technology. [source] Electrophoretically mediated microanalysis with partial filling technique and indirect or direct detection as a tool for inhibition studies of enzymatic reactionELECTROPHORESIS, Issue 7-8 2004Magdaléna Telnarová Abstract The inhibition of the model enzyme, haloalkane dehalogenase from Sphingomonas paucimobilis, was investigated by a combination of electrophoretically mediated microanalysis with a partial filling technique, followed by indirect or direct detection. In this setup, part of the capillary is filled with a buffer suitable for the enzymatic reaction (20 mM glycine buffer, pH 8.6) whereas the rest of the capillary is filled with the background electrolyte optimal for separation of substrates and products. Two different background electrolytes and corresponding detection approaches were used to show the versatility of the developed method. The inhibition effect of 1,2-dichloroethane on the dehalogenation of brominated substrate 1-bromobutane was studied by means of 10 mM chromate , 0.1 mM cetyltrimethylammonium bromide (pH 9.2) in combination with indirect detection or 20 mM ,-alanine , hydrochloric acid (pH 3.5) in combination with direct detection. The method was used to estimate the inhibition constant KI (0.44 mM by indirect detection and 0.63 mM by of direct detection) and to determine the inhibition type. Compared to spectrophotometric and other discontinuous assays, the method is rapid, can be automated, and requires only small amount of reagents that is especially important in the case of enzymes and inhibitors. [source] Oxidative Amidation of Aldehydes and Alcohols with Primary Amines Catalyzed by KI-TBHPEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2008K. Rajender Reddy Abstract Oxidative amidation of aldehydes and alcohols with amines to afford the corresponding amides in excellent yields and ee values over 98,% is achieved by using a catalytic amount of KI in combination with TBHP as the external oxidant. This method avoids the use of expensive and/or air-sensitive reagents. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Fatigue of shot peened 7075-T7351 SENB specimen , A 3-D analysisFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 6 2006T. HONDA ABSTRACT As-received or shot peened 7075-T7351 single-edged notch bend (SENB) specimens, 8.1-mm thick, were fatigued at a constant maximum load and at stress ratios of R= 0.1 and 0.8 to predetermined numbers of fatigue cycles or to failure. The SENB specimens were then fractured by overload and the tunnelling crack profiles were recorded. The crack-growth rate, da/dN, after crack initiation at the notch was determined by crack-profile measurement and fractography at various fatigue cycles. The shot peened surface topography and roughness was also evaluated by three-dimensional (3-D) laser scanning microscopy. Residual stresses in the as-received specimens and those generated by shot peening at Almen scales of 0.004A, 0.008A, 0.012A and 0.016A, were measured by an X-ray diffraction stress analyser with an X-ray target, CrK, every 0.1 mm to a depth of 1 mm. The 3-D stress intensity factor of the curved crack front was determined by the superposition of the 3-D finite element solutions of the stress intensity factor of the loaded SENB specimen without the residual stress and the stress intensity factor of the unloaded SENB specimen with a prescribed residual stress distribution. da/dN versus the resultant stress intensity factor amplitude, ,KI, plots showed that while the residual stress locally retarded the crack-growth rate it had no effect on the overall crack-propagation rate. [source] On the mechanism of fatigue failure in the superlong life regime (N>107 cycles).FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 11 2000Part II: influence of hydrogen trapped by inclusions High cycle fatigue fracture surfaces of specimens in which failure was initiated at a subsurface inclusion were investigated by atomic force microscopy and by scanning electron microscopy. The surface roughness Ra increased with radial distance from the fracture origin (inclusion) under constant amplitude tension,compression fatigue, and the approximate relationship: Ra,,,C,K,2I holds. At the border of a fish-eye there is a stretched zone. Dimple patterns and intergranular fracture morphologies are present outside the border of the fish-eye. The height of the stretch zone is approximately a constant value around the periphery of the fish-eye. If we assume that a fatigue crack grows cycle-by-cycle from the edge of the optically dark area (ODA) outside the inclusion at the fracture origin to the border of the fish-eye, we can correlate the crack growth rate da/dN, stress intensity factor range ,KI and Ra for SCM435 steel by the equation and by da/dN proportional to the parameter Ra,. Integrating the crack growth rate equation, the crack propagation period Np2 consumed from the edge of the ODA to the border of the fish-eye can be estimated for the specimens which failed at Nf,>,107. Values of Np2 were estimated to be ,1.0,×,106 for the specimens which failed at Nf,,,5,×,108. It follows that the fatigue life in the regime of Nf >107 is mostly spent in crack initiation and discrete crack growth inside the ODA. [source] Kinetics of inhibition of acetylcholinesterase in the presence of acetonitrileFEBS JOURNAL, Issue 8 2009Markus Pietsch The hydrolysis of acetylthiocholine by acetylcholinesterase from Electrophorus electricus was investigated in the presence of the inhibitors tacrine, gallamine and compound 1. The interaction of the enzyme with the substrate and the inhibitors was characterized by the parameters KI, ,,, b or ,, Km and Vmax, which were determined directly and simultaneously from nonlinear Michaelis,Menten plots. Tacrine was shown to act as a mixed-type inhibitor with a strong noncompetitive component (,, , 1) and to completely block deacylation of the acyl-enzyme. In contrast, acetylcholinesterase inhibition by gallamine followed the ,steric blockade hypothesis', i.e. only substrate association to as well as substrate/product dissociation from the active site were reduced in the presence of the inhibitor. The relative efficiency of the acetylcholinesterase,gallamine complex for the catalysis of substrate conversion was determined to be 1.7,25% of that of the free enzyme. Substrate hydrolysis and the inhibition of acetylcholinesterase were also investigated in the presence of 6% acetonitrile, and a competitive pseudo-inhibition was observed for acetonitrile (KI = 0.25 m). The interaction of acetylcholinesterase with acetonitrile and tacrine or gallamine resulted in a seven- to 10-fold increase in the KI values, whereas the principal mode of inhibition was not affected by the organic solvent. The determination of the inhibitory parameters of compound 1 in the presence of acetonitrile revealed that the substance acts as a hyperbolic mixed-type inhibitor of acetylcholinesterase. The complex formed by the enzyme and the inhibitor still catalysed product formation with 8.7,9.6% relative efficiency. [source] Kinetic mechanism for p38 MAP kinase ,FEBS JOURNAL, Issue 18 2005A partial rapid-equilibrium random-order ternary-complex mechanism for the phosphorylation of a protein substrate p38 Mitogen-activated protein kinase alpha (p38 MAPK,) is a member of the MAPK family. It is activated by cellular stresses and has a number of cellular substrates whose coordinated regulation mediates inflammatory responses. In addition, it is a useful anti-inflammatory drug target that has a high specificity for Ser-Pro or Thr-Pro motifs in proteins and contains a number of transcription factors as well as protein kinases in its catalog of known substrates. Fundamental to signal transduction research is the understanding of the kinetic mechanisms of protein kinases and other protein modifying enzymes. To achieve this end, because peptides often make only a subset of the full range of interactions made by proteins, protein substrates must be utilized to fully elucidate kinetic mechanisms. We show using an untagged highly active form of p38 MAPK,, expressed and purified from Escherichia coli[Szafranska AE, Luo X & Dalby KN (2005) Anal Biochem336, 1,10) that at pH 7.5, 10 mm Mg2+ and 27 °C p38 MAPK, phosphorylates ATF2,115 through a partial rapid-equilibrium random-order ternary-complex mechanism. This mechanism is supported by a combination of steady-state substrate and inhibition kinetics, as well as microcalorimetry and published structural studies. The steady-state kinetic experiments suggest that magnesium adenosine triphosphate (MgATP), adenylyl (,,,-methylene) diphosphonic acid (MgAMP-PCP) and magnesium adenosine diphosphate (MgADP) bind p38 MAPK, with dissociation constants of KA = 360 µm, KI = 240 µm, and KI > 2000 µm, respectively. Calorimetry experiments suggest that MgAMP-PCP and MgADP bind the p38 MAPK,,ATF2,115 binary complex slightly more tightly than they do the free enzyme, with a dissociation constant of Kd , 70 µm. Interestingly, MgAMP-PCP exhibits a mixed inhibition pattern with respect to ATF2,115, whereas MgADP exhibits an uncompetitive-like pattern. This discrepancy occurs because MgADP, unlike MgAMP-PCP, binds the free enzyme weakly. Intriguingly, no inhibition by 2 mm adenine or 2 mm MgAMP was detected, suggesting that the presence of a ,-phosphate is essential for significant binding of an ATP analog to the enzyme. Surprisingly, we found that inhibition by the well-known p38 MAPK, inhibitor SB 203580 does not follow classical linear inhibition kinetics at concentrations >,100 nm, as previously suggested, demonstrating that caution must be used when interpreting kinetic experiments using this inhibitor. [source] The structural comparison of the bacterial PepX and human DPP-IV reveals sites for the design of inhibitors of PepX activityFEBS JOURNAL, Issue 8 2005Pascal Rigolet X-prolyl dipeptidyl aminopeptidases (X-PDAP) are enzymes catalysing the release of dipeptides from the amino termini of polypeptides containing a proline or an alanine at the penultimate position. Involved in various mammalian regulation processes, as well as in chronic human diseases, they have been proposed to play a role in pathogenicity for Streptococci. We compared the structure of X-PDAP from Lactococcus lactis (PepX) with its human counterpart DPP-IV. Despite very different overall folds, the residues most implicated for X-PDAP activity are conserved in the same positions and orientations in both enzymes, thus defining a structural signature for the X-PDAP specificity that crosses the species frontiers of evolution. Starting from this observation, we tested some inhibitors of DPP-IV on PepX activity, for which no specific inhibitor is known. We thus found that PepX was highly sensitive to valine-pyrrolidide with a KI of 9.3 µm, close to that reported in DPP-IV inhibition. We finally used the structure of PepX from L. lactis as a template for computer-based homology modeling of PepX from the pathogenic Streptococcus gordonii. Docking simulations of valine-pyrrolidide into the active site of PepX led to the identification of key residues for a rational drug design against PepX from Streptococci. These results could have applications in human health giving new perspectives to the struggle against pathogens. [source] A Thermoplastic Gel Electrolyte for Stable Quasi-Solid-State Dye-Sensitized Solar Cells,ADVANCED FUNCTIONAL MATERIALS, Issue 15 2007H. Wu Abstract Dye-sensitized solar cells (DSSCs) are receiving considerable attention as low-cost alternatives to conventional solar cells. In DSSCs based on liquid electrolytes, a photoelectric efficiency of 11,% has been achieved, but potential problems in sealing the cells and the low long-term stability of these systems have impeded their practical use. Here, we present a thermoplastic gel electrolyte (TPGE) as an alternative to the liquid electrolytes used in DSSCs. The TPGE exhibits a thermoplastic character, high conductivity, long-term stability, and can be prepared by a simple and convenient protocol. The viscosity, conductivity, and phase state of the TPGE can be controlled by tuning the composition. Using 40,wt,% poly(ethylene glycol) (PEG) as the polymeric host, 60,wt,% propylene carbonate (PC) as the solvent, and 0.65,M KI and 0.065,M I2 as the ionic conductors, a TPGE with a conductivity of 2.61,mS,cm,2 is prepared. Based on this TPGE, a DSSC is fabricated with an overall light-to-electrical-energy conversion efficiency of 7.22,% under 100,mW,cm,2 irradiation. The present findings should accelerate the widespread use of DSSCs. [source] Peroxide/Potassium Iodide Redox Systems for in situ Oxyiodination of Organic Compounds under Liquid-Phase and Solvent-Free ConditionsHELVETICA CHIMICA ACTA, Issue 2 2010Gattu Venkateshwarlu Abstract Iodination of certain aromatic amines and phenols are triggered by the oxidation of KI by peroxy compounds such as tert -butyl hydroperoxide (tBuOOH) under liquid-phase and solvent-free conditions by grinding the reactants in a mortar with a pestle. The reactions afforded corresponding iodo derivatives in good yield with high regioselectivity (Table,1). [source] Crack edge element of three-dimensional displacement discontinuity method with boundary division into triangular leaf elementsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 6 2001H. Li Abstract In this paper, the existing Displacement Discontinuity Method (DDM) for three-dimensional elastic analysis with boundary discretized into triangular elements, which is purely based on analytical integrals, is extended from the constant element to the square-root crack edge element. In order to evaluate the singular integral when the receiver point falls into the remitter element, i.e., the observed point (x,y) ,,, a part analytical and part numerical integration procedure is adopted effectively. The newly developed codes prove valid in estimating the Stress Intensity Factor (SIF) KI. Furthermore, for the sake of keeping the advantages of high-speed and high-accuracy in developing the numerical system, a novel method to realize pure analytical integration of influence function is found by the aid of symbolic computation technology of Mathematica. Copyright © 2001 John Wiley & Sons, Ltd. [source] An effective iodide formulation for killing Bacillus and Geobacillus spores over a wide temperature rangeJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2004N. Kida Abstract Aims:, To develop a sporicidal reagent which shows potent activity against bacterial spores not only at ambient temperatures but also at low temperatures. Methods and Results:, Suspension tests on spores of Bacillus and Geobacillus were conducted with the reagent based on a previously reported agent (N. Kida, Y. Mochizuki and F. Taguchi, Microbiology and Immunology 2003; 47: 279,283). The modified reagent (tentatively designated as the KMT reagent) was composed of 50 mmol l,1 EDTA-2Na, 50 mmol l,1 ferric chloride hexahydrate (FeCl3·6H2O), 50 mmol l,1 potassium iodide (KI) and 50% ethanol in 0·85% NaCl solution at pH 0·3. The KMT reagent showed significant sporicidal activity against three species of Bacillus and Geobacillus spores over a wide range of temperature. The KMT reagent had many practical advantages, i.e. activity was much less affected by organic substances than was sodium hypochlorite, it did not generate any harmful gas and it was stable for a long period at ambient temperatures. The mechanism(s) of sporicidal activity of the KMT reagent was considered to be based on active iodine species penetrating the spores with enhanced permeability of the spore cortex by a synergistic effect of acid, ethanol and generated active oxygen. Conclusions:, The data suggest that the KMT reagent shows potent sporicidal activity over a wide range temperatures and possesses many advantages for practical applications. Significance and Impact of the Study:, The results indicate development of a highly applicable sporicidal reagent against Bacillus and Geobacillus spores. [source] Synergistic effect of halide ions and polyethylene glycol on the corrosion inhibition of aluminium in alkaline mediumJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2009S.A. Umoren Abstract The corrosion inhibition of aluminium in alkaline medium was studied at 30 and 40°C in the presence of polyethylene glycol (PEG) using gravimetric (weight loss) and thermometric techniques. The effect of halides (KCl, KBr, and KI) on the inhibitory action of PEG was also studied. It was found that PEG acted as inhibitor for aluminium corrosion in the alkaline medium. Inhibition efficiency increased with increasing inhibitor concentration. An increase in temperature led to increase in both the corrosion rate and inhibition efficiency in the absence and presence of inhibitor and halides. Phenomenon of chemical adsorption mechanism is proposed from the values of Ea, Qads, and ,G obtained. The adsorption of PEG on the surface of aluminium was found to obey Flory,Huggins and Temkin adsorption isotherms. The synergism parameter, S1 evaluated was found to be greater than unity indicating that the enhanced inhibition efficiency caused by the addition of halides is synergistic in nature. The inhibition efficiency, surface coverage and synergism parameter increased in the order; I,> Br,> Cl, showing that a joint adsorption of PEG and halide ions on aluminium plays a significant role in the adsorption process. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Purification and characterization of tannin acyl hydrolase from Aspergillus niger MTCC 2425JOURNAL OF BASIC MICROBIOLOGY, Issue 6 2003Rita Bhardwaj The present investigation was carried out for increasing the yield of tannase of Aspergillus niger and the physico-chemical characterization of this enzyme. Homogenization and detergent pretreatments did not have any remarkable effect on the extraction of enzyme protein. However, extraction of fungal pigments and proteins was observed to have high pH dependence, and maximum enzyme extraction was obtained at pH 5.5. The two-step purification protocol gave 51-fold purified enzyme with a yield of 20%. The total tannase activity was made up of nearly equal activity of esterase and depsidase. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of purified tannase protein indicated it to be made up of two polypeptides of molecular weight 102 and 83 kDa. Based on the Michaelis-Menten constant (Km) of tannase for three substrates tested, tannic acid was the best substrate with Km of 2.8 × 10,4M, followed by methyl gallate and propyl gallate. The inhibition was maximum for CaCl2 (58%) whereas EDTA had no modulatory effect on tannase activity. The inhibitor binding constant (KI) of CaCl2 was 5.9 × 10,4M and the inhibition was of noncompetitive type. [source] Kinetics and thermodynamics of glucoamylase inhibition by lactate during fermentable sugar production from food wasteJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2010Xiao Qiang Wang Abstract BACKGROUND: Glucoamylase hydrolysis is a key step in the bioconversion of food waste with complicated composition. This work investigated the effect of lactate on glucoamylase from Aspergillus niger UV-60, and inhibition mechanisms of glucoamylase by lactate during food waste hydrolysis. RESULTS: For 125 min hydrolysis of food waste (10%, dry basis), reducing sugars produced in the absence of lactate were 15%, 26% and 56% more than those produced in the presence of 24 g L,1 lactate at 60, 50 and 40 °C, respectively. Kinetic study showed that the type of glucoamylase inhibition by lactate was competitive, and Km (Michaelis-Menten constent), Vmax (maximum initial velocity), KI (inhibition constant) were 103.2 g L,1, 5.0 g L,1 min,1, 100.6 g L,1, respectively, for food waste hydrolysis at 60 °C and pH 4.6. Lactate also accelerated glucoamylase denaturation significantly. Activation energy of denaturation without inhibitor was 61% greater than that of denaturation with inhibitor (24 g L,1 lactate). Half-lives (t1/2) without inhibitor were 7.6, 2.7, 2.6, 1.7 and 1.2 times longer than those with inhibitor at temperature 40, 45, 50, 55 and 60 °C, respectively. CONCLUSION: These results are helpful to process optimization of saccharification and bioconversion of food waste. Copyright © 2010 Society of Chemical Industry [source] Extraction and recovery of gold from KAu(CN)2 using cetyltrimethylammonium bromide microemulsionsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 11 2001Tian-Xi Zhang Abstract Extraction and stripping of KAu(CN)2 from alkaline solution by a w/o microemulsion formed with cetyltrimethylammonium bromide (CTAB) using 198Au(I) tracer has been investigated. Various parameters, such as the Au(I) concentration in aqueous phase, concentrations of halide ions, NH4SCN and thiodiethylene glycol in stripping solution as well as the relationship between water and Au(I) concentration in the organic phase in the extraction and stripping of Au(I) were studied. The results show that almost all of the Au(I) in the aqueous phase was extracted into the organic phase. The water content decreased significantly with an increase in Au(I) concentration in the organic phase, contrary to the results of a system with tributyl phosphate (TBP) as cosolvent. Almost all of the extracted Au(I) (,98%) can be recovered with pure thiodiethylene glycol as the stripping agent, and ,93% of the Au(I) is stripped with high concentrations of NH4SCN(>3.0,mol,dm,3) or KI (>2.0,mol,dm,3). © 2001 Society of Chemical Industry [source] The use of fall prevention guidelines in German hospitals , a multilevel analysisJOURNAL OF EVALUATION IN CLINICAL PRACTICE, Issue 3 2010Kathrin Raeder MA RN Abstract Aims, Falls and fall-related injuries are major problems in hospitals. The aim of this study was to examine the impact of fall prevention guidelines on falls and fall-related injuries in hospitals. Method, A cross-sectional study was conducted in German hospitals. Some 28 hospitals participated with a total of 5046 patients. Eleven of these hospitals had already implemented a fall prevention guideline, 10 were in the process of developing such a guideline and seven hospitals were not using any fall prevention guideline at all. A standardized questionnaire was used on the individual patient level to obtain details regarding the socio-demographic background, falls, fall-related injuries and other problems relevant to nursing. A further questionnaire referred to the use of fall prevention guidelines in the individual hospitals. Data specific to falls were analysed both on hospital level and on ward and patient level by means of a multilevel logistic model. Results, The univariate analyses suggest that patients in hospitals that are using guidelines are more likely to fall [odds ratios (OR) = 1.19, confidential interval (CI) = 0.65,2.18] than in hospitals that do not use any guideline (reference category) or are still in the developing stage (OR = 0.82, KI = 0.77,0.87). If, in a multivariate analysis, the ward level and individual patient variables (age, disorientation, confusion, incontinence) are included, the following results are obtained: the probability of falls in hospitals not using guidelines (reference category) is higher than in hospitals developing a guideline (OR = 0.86, KI = 0.58,1.28) or using a guideline (OR = 0.71, KI = 0.44,1.14). The differences are even more distinct regarding the injuries resulting from a fall that require medical treatment. The probability of these injuries is significantly lower in hospitals using guidelines (OR = 0.27, KI = 0.09,0.85) than in hospitals developing a guideline (OR = 0.61, KI = 0.24,1.54) or not using any guidelines at all (reference category). Conclusion, The present results of the multilevel analysis show that falls and fall-related injuries can be reduced by the implementation of fall prevention guidelines. [source] Hydrodynamic Cavitation to Improve Bulk Fluid to Surface Mass Transfer in a Nonimmersed Ultraviolet System for Minimal Processing of Opaque and Transparent Fluid FoodsJOURNAL OF FOOD SCIENCE, Issue 9 2007P.J. Milly ABSTRACT:, Ultraviolet (UV)-induced chemical reactions and inactivation of microorganisms in transparent and opaque fluids are strongly dependent upon the homogenous exposure of the target species to the UV irradiation. Current UV technologies used in water disinfection and food preservation applications have limited efficacy due to suspended particles shading target species. An Ultraviolet-Shockwave PowerÔ Reactor (UV-SPR) consisting of an inner rotating rotor and a stationary quartz housing and 2 end plates was used to induce ,controlled cavitation.' Eight UV low-pressure mercury lamps spaced uniformly were installed lengthwise around the quartz housing periphery. A KI to I3,chemical dosimeter for UV was used to quantify photons received by fluid in the annular space of the SPR. UV dose (J/m2) increased from 97 J/m2 at 0 rpm to over 700 J/m2 for SPR speeds above 2400 rpm. Inactivation of E. coli 25922 in apple juice and skim milk in the UV-SPR at exit temperatures below 45 °C was greater than 4.5 and 3 logs, respectively. The UV-SPR system proved successful in increasing the mass transfer of transparent and opaque fluid to the UV irradiated surface. [source] UV laser-induced desorption mechanism analyzed through two-layer alkali halide samplesJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 5 2008F. A. Fernández-Lima Abstract Time of flight-mass spectrometry (TOF-MS) is used to analyze positive and negative desorbed ions generated by UV laser ablation of several alkali (X) halide (Y) salts. Most of the observed desorbed cluster ions have the structure (XY)nX+ or (XY)nY,. Their desorption yields decrease as exp(,kn), where k , 2 for both series, suggesting that the neutral component (XY)n plays the dominant role in the desorption process. Mass spectrum measurements were performed for compound samples in which two salts (out of CsI, RbI, KBr, KCl and KI) are homogeneously mixed or disposed in two superposed layers. The detection of small new ion species and large cluster ions of the original salts supports the scenario that the uppermost layers are completely atomized while deep layers are emitted colder and fragmented: It is proposed that ns-pulsed laser induced desorption of ionic salts occurs via two sequential mechanisms: (1) ejection of cations and anions in the hot plume, followed by recombination into new cluster ions and (2) ejection of relatively cold preformed species originated from deep layers or from periphery of the irradiated region. Copyright © 2007 John Wiley & Sons, Ltd. [source] Quantitation of sleep and spinal curvature in an unusually longevous owl monkey (Aotus azarae)JOURNAL OF MEDICAL PRIMATOLOGY, Issue 6 2006Juri Suzuki Abstract Background, A table summarizing the primary literature on 19 species of longevous non-human primates, other than owl monkey, is presented. Methods, We prospectively quantitated the sleep of a longevous female owl monkey (Aotus azarae), aged >30 years, longitudinally for 2 years and also evaluated the senility-induced change in spinal curvature. Results, The mean daily total sleep time (TST) of this monkey ranged between 790 and 1106 minutes, and was markedly higher in comparison with its female progeny (aged 16 years and used as a control) whose daily TST during the same experimental period ranged between 612 and 822 minutes. Conclusions, The calculated kyphotic index (KI) of 2.27 for this monkey, compared with the KIs 4.83 and 5.42, for its progeny and female grandprogeny (aged 1 year) respectively, confirmed the prominent spinal curvature. [source] Synthesis and solution properties of a new pH-responsive polymer containing amino propanesulfonic acid residuesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2003Sk. Asrof Ali Abstract The reaction of diallyl amine with 1,3-propane sultone led to the synthesis of the zwitterionic monomer 3-(N,N -diallylammonio)propanesulfonate. The sulfobetaine was cyclopolymerized in water in the presence of sodium chloride with t -butylhydroperoxide as an initiator to afford a polysulfobetaine (PSB) in very good yield. PSB, upon treatment with sodium hydroxide, was converted into an anionic polyelectrolyte (APE). Although APE was readily soluble in salt-free water, PSB needed the presence of low-molecular-weight salts (e.g., NaCl, KI, etc., in the range of 0.135,1.04 N) for its dissolution. The solution properties of PSB and APE were investigated with potentiometric and viscometric techniques. The basicity constant of the amine was apparent and followed the modified Henderson,Hasselbalch equation; as the degree of protonation (,) of the whole macromolecule increases, the protonation of the amine nitrogens becomes increasingly more difficult. The composition and phase diagram of the aqueous two-phase systems of APE/PSB and poly(ethylene glycol) were also explored. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 172,184, 2003 [source] Alcohol-Induced Tolerance and Physical Dependence in Mice With Ethanol Insensitive ,1 GABAA ReceptorsALCOHOLISM, Issue 2 2009David F. Werner Background:, Although many people consume alcohol (ethanol), it remains unknown why some become addicted. Elucidating the molecular mechanisms of tolerance and physical dependence (withdrawal) may provide insight into alcohol addiction. While the exact molecular mechanisms of ethanol action are unclear, ,-aminobutyric acid type A receptors (GABAA -Rs) have been extensively implicated in ethanol action. The ,1 GABAA -R subunit is associated with tolerance and physical dependence, but its exact role remains unknown. In this report, we tested the hypothesis that ,1-GABAA -Rs mediate in part these effects of ethanol. Methods:, Ethanol-induced behavioral responses related to tolerance and physical dependence were investigated in knockin (KI) mice that have ethanol-insensitive ,1 GABAA -Rs and wildtype (WT) controls. Acute functional tolerance (AFT) was assessed using the stationary dowel and loss of righting reflex (LORR) assays. Chronic tolerance was assessed on the LORR, fixed speed rotarod, hypothermia, and radiant tail-flick assays following 10 consecutive days of ethanol exposure. Withdrawal-related hyperexcitability was assessed by handling-induced convulsions following 3 cycles of ethanol vapor exposure/withdrawal. Immunoblots were used to assess ,1 protein levels. Results:, Compared with controls, KI mice displayed decreased AFT and chronic tolerance to ethanol-induced motor ataxia, and also displayed heightened ethanol-withdrawal hyperexcitability. No differences between WT and KI mice were seen in other ethanol-induced behavioral measures. Following chronic exposure to ethanol, control mice displayed reductions in ,1 protein levels, but KIs did not. Conclusions:, We conclude that ,1-GABAA -Rs play a role in tolerance to ethanol-induced motor ataxia and withdrawal-related hyperexcitability. However, other aspects of behavioral tolerance and physical dependence do not rely on ,1-containing GABAA -Rs. [source] Abstracts of the 8th Meeting of the Italian Peripheral Nerve Study Group: 79JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 1 2003U Del Carro Peripheral neuropathy is one of the most common secondary complications of diabetes mellitus, causing severe and prolonged morbidity. However, clinical and experimental studies have reported that careful glucose control may prevent, stabilize, and/or reverse neuropathy and other chronic diabetic complications. Unfortunately, insulin therapy does not prevent the development or progression of chronic lesions in the vessels, kidneys, eyes, or nerves of the diabetic patient. There is great interest in investigating other forms of endocrine replacement therapy, such as transplantation of the pancreas or of the islets of Langerhans (IT). Diabetic polyneuropathy (DP) evolution is characterized by progressive demyelination and axonal loss and is manifested by signs and symptoms on physical examination and abnormalities in nerve conduction studies (NCS). NCS provide reliable, noninvasive, objective measures of peripheral nerve function and constitute the most important technique for the evaluation of the severity of DP in clinical trials. Several research groups have demonstrated that skin biopsy with measurement of intraepidermal nerve fiber density is another method minimally invasive and repeatable that provides direct pathologic evidence of axonal damage in diabetic neuropathy. Fifty-one consecutive IDDM patients with or without end stage renal disease were enrolled at the moment of islet (Is), kidney (KD), kidney-pancreas (KP) or kidney-islet (KI) transplantation. Patients underwent skin biopsy punch, neurologic examination and neurophysiological investigation. Particularly, 20 pts underwent KP tx, 16 KD tx, 10 islet tx and 5 KI. The patients were comparable for duration of diabetes, dialysis (when present), age, lipid profile. In half of the patients a follow-up of 2 years has been reached. After KP tx, and partially with KI, a complete normalization of glycometabolic control has been achieved, with statistically lower HbA1c in comparison with KD group (KP = 6.2; 0.1% vs. KD = 8.4; 0.5%; p < 0.01). In the KI/Is group, a long-term restoration of islet endocrine function has been achieved, with insulin independence. When this has been lost, a persistent secretion of C-peptide was shown for a long period of time. This was correlated with a global improvement quality of life and vascular structure. Preliminary results will be presented. [source] Catalytic resonance scattering spectral determination of ultratrace horseradish peroxidase using rhodamine SLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 3 2009Zhiliang Jiang Abstract A highly sensitive and selective resonance scattering spectral assay was proposed for the determination of horseradish peroxidase (HRP), based on its catalytic effect on the H2O2 oxidation of KI to form I3,. The I3, combined respectively with rhodamine (Rh) dye such as rhodamine S (RhS), rhodamine 6G (Rh6G), rhodamine B (RhB) and butyl-rhodamine B (b-RhB), to form association particles (Rh-I3)n. The four Rh systems all exhibit a stronger resonance scattering (RS) peak at 424 nm. For the RhS, Rh6G, RhB and b-RhB systems, HRP concentration in the range of 3.2 × 10,12 to 4.8 × 10,9, 2 × 10,11 to 3.2 × 10,9, 1.6 × 10,11 to 3.2 × 10,9 and 1.6 × 10,11 to 4 × 10,9 g/mL was linear to its RS intensity at 424 nm, with a detection limit of 2.2 × 10,12, 2.5 × 10,12, 4.4 × 10,12 and 2.6 × 10,12 g/mL, respectively. This RhS system was most sensitive and stable, and was applied for the determination of HRP in the hepatitis B surface antibody labeling HRP and water samples, with satisfactory results. Copyright © 2009 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||||||||