A predicted three-dimensional structure for the human immunodeficiency virus binding domains of CD4 antigen

A predicted three-dimensional structure of the two N-terminalextracellular domains of human CD4 antigen, a cell surface glycoprotein,is reported. This region of CD4, particularly the first domain,has been identified as containing the binding region for theenvelope gp120 protein of the human immuno-deficiency virus.The model was predicted based on the sequence homology of eachdomain with the variable light chain of immunoglobulins. Theframework ß-sheet regions were taken from the crystalcoordinates of REI. For one region in the first domain of CD4there was an ambiguity in the alignment with REI and two alternatemodels are presented. Loops connecting the framework were modeledfrom fragments selected from a database of main chain coordinatesfrom all known protein structures. Residues identified as involvedin binding gp120 have been located in several other studieswithin the first domain of CD4. Epitopes from eight monoclonalantibodies have been mapped onto residues in both domains. Competitionof these antibodies with each other and with gp120 can be interpretedfrom the structural model.     

UV‐radiation–induced preirradiation grafting of methyl methacrylate onto lignocellulose fiber in an aqueous medium and characterization

The preirradiation method of grafting has been established by ultraviolet radiation. Methyl methacrylate (MMA) was grafted onto jute fiber in an aqueous medium. The variation of graft weight with UV‐radiation time, monomer concentration, and reaction time was investigated. The conversion of monomer into homopolymer and graft copolymer was evaluated. The graft weight passes through a maximum value (～ 122%) with UV‐radiation time. The optimum value of the monomer concentration was evaluated for maximum degree of grafting. Graft copolymerization of MMA onto lignocellulose fiber significantly increases the elongation at break (～ 65%) compared to that of the “as‐received” sample. However, a linear decrease on breaking load was observed with the increase of graft weight. The estimation of degree of grafting was achieved using an IR technique by correlating band intensities with the degree of grafting. Considering the water‐absorption property, the grafted sample showed a maximum up to 61% decrease in hydrophilicity compared to that of the as‐received sample. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1667–1675, 2004     

Polyurethane composites based on oil palm empty fruit bunches: Effect of isocyanate/hydroxyl ratio and chemical modification of empty fruit bunches with toluene diisocyanate and hexamethylene diisocyanate on mechanical properties

This study focuses on the effect of isocyanate (NCO)/hydroxyl (OH) group ratios and chemical modification of oil palm empty fruit bunches (EFBs) with toluene diisocyanate (TDI) and hexamethylene diisocyanate (HMDI) on the mechanical properties of EFB–polyurethane (PU) composites. The tensile, flexural, and impact properties are affected by the NCO/OH ratios. The tensile strengths, flexural strengths, and toughness increase as the NCO/OH increases; however, the modulus decreases. The reduction in the modulus is attributable to the increased flexibility of the PU linkages. Chemical modification of the EFBs increases the tensile strength, flexural strength, and toughness; however, the modulus is lowered as the percentage of treated EFB is increased. Impact strength results show that the strength increases as the NCO/OH ratio is increased. At NCO/OH ratios of 1.0 and 1.1, the composites with HMDI‐treated fibers exhibit higher impact strength than those with TDI‐treated and untreated fibers, respectively. This may be due to the longer and more flexible chain length of HMDI as compared to TDI, which enables the composites to absorb more energy before failure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Multimedia framework to support eHealth applications

Limited bandwidth resources lead to a number of challenges especially for eHealth applications, which are communicated over IP and wireless networks. These multimedia services include high-resolution videos and have very large file sizes that require a high level of compression to overcome this limitation. Therefore, there is an acute demand for the research community to provide an efficient multimedia framework to encode medical videos with high quality specifically under the conditions of an error-prone environment. Both an affordable delivery framework and effective coding techniques are extremely desirable for the delivery of high-quality eHealth video applications for transmission over heterogeneous networks and devices. In this paper, we propose and demonstrate a multimedia framework to support eHealth applications, which has an improved coding scheme that uses an SVC-scalable extension of MPEC-4 AVC/H.264. Simulation results show that the proposed scheme achieves a significant improvement in terms of the PSNR-Y gain and reduces the picture quality degradation caused by artifacts and distortions, compared to the existing scheme.     

The impact of interaction quality factors on the effectiveness of Web-based information system: the mediating role of user satisfaction

Recently, IS researchers have focused on the assessment of Web-based information system (WBIS) at the individual level as it highly contributes to the organizations’ employees. The evaluation and development of WBIS is significantly needed because the top management is in need of justifying their costly IT investment in terms of its impacts on employee performance. For this purpose, this study is primarily concerned with the development and validation of new multidimensional instrument, and also a theoretical framework for assessing the impacts of user interface quality, online communication quality, and user satisfaction on the effectiveness of Web employee portals. The effectiveness is assessed in terms of contextual performance. In a large-scale study, a sample of 384 United Nations Relief and Works Agency for Palestine Refugees respondents are gathered in order to validate and check the reliability of the adapted study instrument. The results of validity and reliability analysis provide enough confidence to proceed toward validating the proposed theoretical framework. The results of multiple-regression analysis indicate that there is a positive significant relationship between user interface quality, communication quality, user satisfaction, and effectiveness at significance level (sig. < 0.01). As another important point, the results of hierarchical regression showed that user satisfaction has a mediating role on the relationship between user interface quality, communication quality, and contextual employee performance. The findings and implications of this research are discussed. Finally, it is expected that this study would contribute to empirical studies in the fields of IS and user behavior assessment.     

Insecticidal Effects of Organotin(IV) Compounds on Plutella Xylostella (L.) Larvae. II. Inhibitory Potencies Against Acetylcholinesterase and Evidence for Synergism in Tests With Bacillus Thuringiensis(BER.) and Malathion

Features of pesticide synergism and acetylcholinesterase (AChE) inhibition (in vitro) were studied using a selected range of organotin compounds against the early 4th instar larvae of a highly resistant strain of the diamondback moth (DBM), Plutella xylostella, a major universal pest of cruciferous vegetables.Fourteen triorganotin compounds were evaluated for their ability to enhance the toxicity of the microbial insecticide, Bacillus thuringiensis (BT) and of the commercial insecticide, Malathion to Plutella xylostella larvae. Supplemental synergism was observed with triphenyl- and tricyclopentyltin hydroxides in combinations with Bacillus thuringiensis. Increased synergism was observed with an increase in the number of cyclopentyl groups on tin in the mixed series, Cyp(n) Ph(3-n) SnX, where X = OH, and 1-(1,2,4-triazolyl). The combination of (p-chlorophenyl)diphenyltin N,N-dimethyldithiocarbamate at LD(10) and LD(25) concentrations with sublethal concentrations of Malathion as well as of tricyclohexyltin methanesulphonate at the 0.01% (w/v) concentration with Malathion exerted strong synergistic effects (supplemental synergism) with toxicity index (T.I) values of 7.2, 19.8 and 10.1, respectively.Studies on the in vitro inhibition of acetylcholinesterase prepared from the DBM larvae showed that while most of the triorganotin Compounds tested were without effect on the enzyme, compounds containing the thiocarbamylacetate or the dithiocarbamylacetate moieties demonstrated appreciable levels of inhibition, being comparable in efficacy to commercial grades of Malathion and Methomyl.     

Effect of Composition on the Electromechanical Properties of (1-x)Pb(Mg1/3Nb2/3)O3−XPbTiO3 Ceramics

Ceramic lead magnesium niobate–lead titanate ((1-x)PMN_-xPT) of different compositions has been prepared by the columbite precursor method. This study discusses compositions ranging from 0.94PMN–0.06PT to 0.60PM–N0.40PT, focusing on two areas of the (1-x)PMN_xPT system: compositions that exhibit electrostrictive behavior, and those that show piezoelectric behavior. In electrostrictive compositions where x is in the range of 0.06–0.20, the dielectric constant and electromechanical coupling factor dependencies on the bias field are evaluated. The optimal electromechanical properties are obtained with the composition 0.82PMN–0.18PT, measured at temperature T = T_m (the temperature of maximum dielectric constant) = 80°C and with a dc bias of 5 kV/cm. X–ray diffractometry is used to show that the (1-x)PMN_-xPT system has a compositionally wide two–phase region and that 0.655PMN–0.345PT is the morphotropic phase boundary (MPB) composition. Electromechanical property evaluation shows that the optimal piezoelectric properties (piezoelectric charge coefficient ( d₃₃ ) value of 720 pC/N, dielectric constant ( K ) value of 5400, and electromechanical planar and thickness coupling coefficient ( k_p and k_t , respectively) values of 62% and 46%, respectively) are obtained at the MPB composition.     

Abutilon indicum Seed Oil — Characterisation of HBr-Reactive Acids

The seed oil of Abutilon indicum (Malvaceae) contains three HBr-reactive fatty acids. These are shown to be cis-12,13-epoxyoleic (vernolic) acid, 1.6% 9,10-methylene-octadec-9-enoic (sterculic) acid, 0.9%; as well as 8,9-methylene-heptadec-8-enoic (malvalic) acid, 2.3%. Quantitative results are obtained by combining informations about the HBr-titration, the preparative thin layer separation of oxygenated and non-oxygenated acids, and gas liquid chromatographic analysis.     

Dishwashing performance of mixed palm stearin sulfonated methyl esters and polyoxyethylene sorbitan esters

The detergency profiles of sodium salt α-sulfonated methyl esters derived from palm stearin (α-SMEPS) and polyoxyethylene (20) sorbitan monoesters (POESE) in mixed micelle systems were evaluated as a function of the weight ratios of α-SMEPS/POESE [polyoxyethylene (20) sorbitan monolaurate (12), polyoxyethylene (20) sorbitan monostearate (18∶0), and polyoxyethylene (20) sorbitan monooleate (18∶1)] at different water hardness values (5.12, 51.2, and 512.0 ppm CaCO₃) and temperatures (20, 30, 45, and 65°C), respectively. All the mixtures of α-SMEPS/POESE (12, 18∶0, and 18∶1) systems exhibited a synergistic effect at 65°C in the absence of hardness. This was evaluated by measuring the percentage of soil removed. The systems showed an increase in detergency with both the temperature and water hardness. Maximal detergency was observed with 5.12 ppm CaCO₃ in the mixed surfactant solution.     

Enhanced halftone-based secure and improved visual cryptography scheme for colour/binary Images

Visual Cryptography (VC) is gaining attraction during the past few years to secure the visual information in the transmission network. It enables the visual data i.e. handwritten notes, photos, printed text, etc. to encrypt in such a way that their decryption can be done through the human visual framework. Hence, no computational assistance is required for the decryption of the secret images they can be seen through naked eye. In this paper, a novel enhanced halftoning-based VC scheme is proposed that works for both binary and color images. Fake share is generated by the combination of random black and white pixels. The proposed algorithm consists of 3 stages i.e., detection, encryption, and decryption. Halftoning, Encryption, (2, 2) visual cryptography and the novel idea of fake share, make it even more secure and improved. As a result, it facilitates the original restored image to the authentic user, however, the one who enters the wrong password gets the combination of fake share with any real share. Both colored and black images can be processed with minimal capacity using the proposed scheme.