Showing papers by "An-Najah National University published in 1998"
TL;DR: The most antimicrobially active plants were Phagnalon rupestre and Micromeria nervosa, whereas, the least active plant was Ziziphus spina-christi.
292 citations
TL;DR: A review with 159 references is presented in this article on the applications of adsorptive stripping voltammetry (AdSV) for determining trace metal ions in different environmental samples (e.g. water, soil, plant, biological fluids).
Abstract: A review with 159 references is presented on the applications of adsorptive stripping voltammetry (AdSV) for determining trace metal ions in different environmental samples (e.g. water, soil, plant, biological fluids). The analytical applications of AdSV to biologically active organic compounds (e.g. pharmaceuticals, pesticides, biomolecules) are also discussed.
61 citations
TL;DR: In this paper, it was shown that the crystallization process for As x Se 1−x, in the composition range investigated, is mainly controlled by the viscosity of the medium, and the reaction totally disappears when the amount of As atoms in the alloys reaches such a value capable of connecting enough Se chains to block their movement.
Abstract: The crystallization of As x Se 1− x from the glassy state (0.005 x x , the apparent activation energy decreases. It is also found that the dependence of the inverse of the apparent activation energy for crystallization falls linearly with the reciprocal of the mean temperature used in the experiment. The latter result unambiguously indicates that the crystallization process for As x Se 1− x , in the composition range investigated, is mainly controlled by the viscosity of the medium. Therefore, the crystallization reaction totally disappears when the amount of As atoms in the alloys reaches such a value capable of connecting enough Se chains to block their movement.
51 citations
TL;DR: The complete solution for the energy eigenfunctions is presented and the radial distribution function is examined in this paper, where the effect of the effective potential manifests itself in some of the aspects being investigated.
Abstract: Some aspects of the N-dimensional hydrogen atom are discussed. The complete solution for the energy eigenfunctions is presented and the radial distribution function is examined. Degeneracy of energy levels, expectation values (^ 1/r& and ^ 1/r 2 & ), and the virial theorem are considered. It is shown that the effect of the effective potential manifests itself in some of the aspects being investigated.
50 citations
TL;DR: An accurate fast spectrophotometric method based on the oxidation of these amino acids by ferric ions in the presence of ferrozine, whereby a violet-coloured complex is formed which absorbs at 562 nm was satisfactory for the determination of cysteine andN-acetylcysteine.
Abstract: An accurate fast spectrophotometric method for the determination of cysteine andN-acetyl-cysteine is presented, based on the oxidation of these amino acids by ferric ions in the presence of ferrozine, whereby a violet-coloured complex is formed which absorbs at 562 nm. The method was satisfactory for the determination of cysteine andN-acetylcysteine in samples within the range 0.02–6.00 μgml−1. Effects of time, acidity, ferric ions, ferrozine, sodium perchlorate concentrations and the tolerance limit for other amino acids have been reported. The method was applied to the determination of cysteine in amino acids mixtures andN-acetylcysteine in pharmaceutical preparations.
47 citations
TL;DR: In this article, a simple model was developed to evaluate the resilient modulus and accumulated permanent strain of cohesive subgrade soils under repeated loads using an empirical model derived from the observed behavior of an A-6 cohesive soil.
Abstract: The resilient modulus and cumulative permanent strain of subgrade soils under anticipated repeated loading are important considerations for the design of a pavement against fatigue and rutting failures. A simple model was developed to evaluate the resilient modulus and accumulated permanent strain of cohesive subgrade soils under repeated loads. The empirical model was derived from the observed behavior of an A-6 cohesive soil. The model was tested against an A-5 soil. The proposed model was found to predict adequately the resilient modulus and the accumulated plastic strain for all A-6 and A-5 specimens with 90 percent confidence intervals of 0.61 and 1.4, and 0.66 and 1.39, respectively.
30 citations
TL;DR: The incidence of tinea capitis was higher in schools in rural areas than in refugee camps or urban areas, and higher disease incidence was found to be correlated with larger family and class sizes.
Abstract: A study of tinea capitis was carried out during the period January-June 1996 in 7525 primary schoolchildren aged 6-14 years comprising 4050 boys and 3475 girls in the Nablus district in the Palestinian area. Fourteen primary schools located in rural, urban and refugee camp areas were surveyed in this study. Seventy-five (1.0%) mycologically proven cases of tinea capitis were detected. The incidence was higher in schools in rural areas (1.9%) than in refugee camps (1.1%) or urban areas (0.4%). Also, the incidence was higher in young children (1.4%) aged 6-10 years than in older children (0.5%) aged 10-14 years. Boys 52 (1.3%) were more commonly affected than girls 23 (0.7%). Higher disease incidence was found to be correlated with larger family and class sizes. Trichophyton violaceum was the most common aetiological agent (82.7%) followed by Microsporum canis (16%) and Trichophyton schoenleinii (1.3%). The findings are discussed in relation to the children's different socioeconomic and hygienic backgrounds. A mycological investigation carried out on 117 tinea capitis cases at a clinic in the area under study showed similar results to those of the school survey.
28 citations
TL;DR: Field soils receiving either raw city wastewater or normal irrigation water, were found to be rich in pathogenic and potentially pathogenic CH-resistant fungi, including dermatophytes, withRaw city wastewater yielding the highest percentage (81%), followed by the newly wastewater irrigated field (77.7%), the nonpolluted field (67%), and the heavily polluted field (63.4%).
Abstract: The effect of raw city wastewater irrigation on biodiversity and population densities of a cycloheximide-resistant (CH) fungal community was studied in 13 field soils receiving either raw city wastewater or normal irrigation, and in raw city wastewater in the Nablus area, using the hair baiting technique (HBT) and a surface soil dilution plating (SSDP) technique Three of these fields [one had been receiving raw city wastewater for more than ten years and was designated a heavily polluted field, and the other 2 were cultivated for the first time and were either irrigated with raw city wastewater (newly polluted field) or normal irrigation water (nonpolluted)], were sampled 4–7 times over a 9-month period The other ten fields, which had been under raw city wastewater irrigation for more than 10 years, were sampled only once Fifty-seven CH-resistant species belonging to 18 genera were recovered, of which 49 species were recovered from soil habitats and 28 species from raw city wastewater The HBT had shown to be more efficient in the isolation of pathogenic and potentially pathogenic fungi including dermatophytes A higher percentage of this group of fungi was recovered from the three main field soils studied using HBT (70% of all isolates), than the SSDP (355%); no dermatophytes were recovered by the SSDP method Two dermatophytes (Microsporum gypseum, and Trichophyton ajelloi), and five more fungi (Arthroderma cuniculi, A curreyi, Chrysosporium keratinophilum, C tropicum, and C pannorum), were recovered from these habitats Wastewater irrigation seemed to have affected the fungal population densities, with the highest population densities being found in the heavily polluted field soil, while lower population densities were found in the nonpolluted field soil Increases in organic matter were also observed as a result of sewage effluent irrigation However, basic similarities in the biodiversity of CH-resistant fungal communities existed in nonpolluted and polluted field soils, and raw city wastewater Comparable numbers of fungal species were recovered from the three main field soils The species most commonly found in those habitats included: Alternaria alternata, Aspergillus candidus, Geotrichum candidum, and Paecilomyces lilacinus Field soils receiving either raw city wastewater or normal irrigation water, were found to be rich in pathogenic and potentially pathogenic CH-resistant fungi, including dermatophytes, with raw city wastewater yielding the highest percentage (81%), followed by the newly wastewater irrigated field (777%), the nonpolluted field (67%), and the heavily polluted field (634%) Hygienic measures should therefore be taken to control the spread of these fungi in the environment of human communities, and to avoid mycotic infections among farmers
26 citations
TL;DR: In this article, a theoretical study of the structural phase transformations of ZnS under high pressure, using first-principles pseudopotential and full-potential linear muffin-tin orbital methods, in which the semicore Zn d electrons are treated as valence states.
Abstract: We present the results of a theoretical study of the structural phase transformations of ZnS under high pressure, using first-principles pseudopotential and full-potential linear muffin-tin orbital methods, in which the semicore Zn d electrons are treated as valence states. The zinc-blende, NaCl and cinnabar forms of ZnS have been considered. The structural properties and the band structures of these systems have also been studied. In the case of the FP-LMTO approach, an optimal choice of the empty spheres, atomic radii and filling percentage is introduced, which gives results in excellent agreement with those of the present pseudopotential method. It has been found that cinnabar phase is not a stable phase in ZnS under high pressure. The cinnabar phase is predicted to be a semiconductor with a direct band gap of about 3.6 eV.
22 citations
TL;DR: In this article, it was shown that an In atom is surrounded by three Se atoms at a distance of about 0.259 nm and forms In 2 Se 3 microclusters.
Abstract: EXAFS measurements were performed, at the In K edge, on devitrified Ge 5 Se 80 In 15 and on a series of vitreous Ge–Se–In alloys. The results indicate that the In atoms have essentially the same local surroundings in all of the samples investigated. We found that an In atom is surrounded by three Se atoms at a distance of about 0.259 nm and forms In 2 Se 3 microclusters.
17 citations
TL;DR: A critical review of current and future water supply planning options and policies in Palestine which faces constrained water supply and highly complex and changing political conditions is offered in this article. But, the review is limited to the immediate phase as well as over the medium and long terms.
TL;DR: In this paper, the compactness of the structure of the chalcogenide glasses is determined from the measured densities of the glasses, and the peculiarities observed in the δ-composition dependence are interpreted by using the ordered bond network model and the topological models proposed to describe the atomic arrangements in these solids.
Abstract: Chalcogenide glasses, from the Ge x In y Se 100− x − y system with y =6 and 12 at%, have been prepared from high purity Ge, In and Se. The compactness, δ, of the structure of the glasses is determined from the measured densities of the glasses. The peculiarities observed in the δ-composition dependence are interpreted by using the ordered bond network model and the topological models proposed to describe the atomic arrangements in these solids.
TL;DR: The underlying assumption seems to be that in addition to the direct social and political benefits of the resultant economic growth, integration will also ensure that peace, once attained, will continue to be maintained, the economic costs of disrupting it becoming prohibitively high.
Abstract: The ongoing peace process in the Middle East has aroused considerable interest in the potential for economic cooperation and integration in the region, especially among the parties to this process. The underlying presumption seems to be that in addition to the direct social and political benefits of the resultant economic growth, integration will also ensure that peace, once attained, will continue to be maintained, the economic costs of disrupting it becoming prohibitively high.
TL;DR: Cross-resistance in two isolates to all aminoglycosides tested suggested membrane impermeability to aminglycosides as the mechanism of resistance, and a chromosomal location is proposed for plasmid-deficient strains.
Abstract: Twenty-four gentamicin-resistant isolates of Enterobacteriaceae, obtained from the clinical laboratories of three health centres in Nablus, Palestine, were tested for susceptibility to neomycin, kanamycin, tobramycin and amikacin. Resistance rates were 29.2% for neomycin, 58.3% for kanamycin, 45.8% for tobramycin and 8.3% for amikacin. Fourteen (58.3%) isolates were noted to be multiresistant, i.e., resistant to gentamicin and two or more other aminoglycosides; resistance to gentamicin, kanamycin and tobramycin was the most common pattern of multiple resistance. This pattern implies the involvement of adenyltransferase ANT(")-I activity. Plasmid profiles and curing experiments suggested a plasmid localisation of gentamicin, neomycin, kanamycin and tobramycin resistance genes. However, a chromosomal location is proposed for plasmid-deficient strains. Cross-resistance in two isolates to all aminoglycosides tested suggested membrane impermeability to aminoglycosides as the mechanism of resistance.
TL;DR: An efficient method for the regioselective synthesis of episulfides, showing remarkable proteinase-inhibiting activity, from cis-oriented anhydro triflate sugars is decribed in this article.
TL;DR: In this article, the authors used differential scanning calorimetry (DSC) and X-ray diffraction (XRD) to investigate the thermal stability of Ge-S-Ag glass.
Abstract: Glasses belonging to the Ge-S-Ag system were investigated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The DSC results show that the glass transition temperature (T g ), the onset crystallization temperature (T c ) as well as the temperature interval (T c - T g ) decrease with increasing amount of Ag content in the glass. The decrease of (T c - T g ) indicates that the thermal stability of the glass decreases. The X-ray structure factors obtained on glasses with 5, 10 and 15 at% Ag have a first sharp diffraction peak (FSDP), characteristic of intermediate range order, whose intensity decreases gradually with increasing Ag content in the glass up to 15 at%. For the glasses with Ag content ≥20 at%, this FSDP is totally absent. These results may be taken as prima facie evidence that the decrease or the absence of intermediate range order in the glass decrease its thermal stability.
TL;DR: In this article, the EXAFS measurements from the In K edge on Ge 23.33 Se 64.67 In 12 glass have been performed, and it is found that In is only coordinated with Se atoms.
TL;DR: In this article, micro-mixing calculations based upon a simplified non-deforming one-dimensional diffusion-reaction formulation are presented for the sequence of three reactions denoted by A + B - R + B + S + B+T + T + T. This triplet reaction is posed as five simultaneous parabolic partial differential equations which have been solved using a general purpose NAG library algorithm.
Abstract: Micro-mixing calculations based upon a simplified non-deforming one-dimensional diffusion-reaction formulation are presented for the sequence of three reactions denoted by A + B - R + B - S + B + T. This triplet reaction under micro-mixing is posed as five simultaneous parabolic partial differential equations which have been solved using a general purpose NAG library algorithm. The primary product R has an improved yield under perfect mixing conditions. The ultimate product T is shown to be always favoured by the perfect segregation of micro-mixing. By contrast, the central intermediate S gives high yields under micro-mixing at low conversions, but perfect mixing is preferable at higher conversions. In addition, predictions show that yield improvements for S might be possible by an engineered stretching of fluid lamellae and by the combination of micro-mixing followed by perfect mixing, especially at intermediate levels of conversion. The calculations are relevant to multi-step halogenations and they help to explain how the anomolous appearance of a tri-halogenated species ahead of mono- and di-halogenated ones in a stirred vessel can be attributed to micro-mixing. Des calculs de micromClange s’appuyant sur une formulation de diffusion-reaction unidimensionnelle non dCformante simplifike sont present& pour une sCquence de trois reactions notees par A + B - R + B + S + B - T. En micromClange, ce triplet s’exprime sous la forme de cinq Cquations diffkrentielles partielles paraboliques simultanCes qui ont CtC rCsolues au moyen d’un algorithme gCnCral de la bibliothkque NAG. Le produit primaire R a un rendement amCliorC dans des conditions de mClange parfaites. On montre que le produit final T est toujours favoris6 par la sCgrCgation parfaite du micromClange. A I’opposC, le rendement en produit intermediaire S est trbs ClevC pour un micromt5lanage B faible conversion, mais un melange parfait est preferable B une conversion ClevCe. De plus, les prCdictions montrent que des arnCliorations du rendement en S pourraient &tre possibles par un Ctirement des lamelles de fluide et par la combinaison d’un micromClange suivi d’un mClange parfait, particulikrement aux niveaux intermkdiaires de conversion. Ces calculs sont pertinents pour les halogdnations multiCtagCes et aident i expliquer comment l’apparence anormale d’une espkce trihalogCnCe devant des espkces mono et dihalogCnCes dans un rkservoir agitC peut &tre attribuie au micromelange.
TL;DR: In this article, the authors evaluated the extent of public concerns about water management in the Palestinian Territory (PT) through a survey of the main Palestinian newspaper over the last thirteen years divided in three periods: pre (1984-1987), during (1988-1991), and post national uprising period (1992-1996).
Abstract: We have evaluated the extent of public concerns about water management in the Palestinian Territory (PT) through a survey of the main Palestinian newspaper over the last thirteen years divided in three periods: pre (1984–1987), during (1988–1991), and post national uprising period (1992–1996). The public concern in the PT about various water management aspects was clear and influenced by the prevailing political conditions indicating (1) poor concerns in the first and second period where full Israeli military control of the PT and harsh practices prevailed with relatively more emphasis on regional water issues and (2) extensive-strong concerns in the third period when the peace process started and a partial lift of some of the Israeli water practices took place, along with an increased freedom in expressing public concerns which was granted with more emphasis on local issues and problems. Lack and limitation of water available to Palestinians, alternative solutions, and water quality and pollution control constituted the overwhelming majority of the topics of concern to the public for the three periods studied. Palestinian concerns were always greater than regional ones for the three periods and all of the topics considered. Public concern in the PT about all other water management aspects was poor and negligible especially in the first two periods. A massive increase in public concern has been observed in the third period in which the public expressed their concern over most water management aspects, indicating a possible change in public attitude toward water and water management and reflecting the change of the political status by the start of the peace process and the signing of the peace agreements.
TL;DR: In this article, the first sharp diffraction peak (FSDP) was observed in bulk glasses with high purity constituent elements and the intensity of this peak increases with the amount of S content in the glasses.
Journal Article•
TL;DR: In this paper, the fine structure of energy levels of a hydrogen atom in N dimensions is given by calculating the first-order energy corrections due to relativistic correction to kinetic energy, spin-orbit coupling, and Darwin term.
Abstract: The fine structure of energy levels of a hydrogen atom in N dimensions is given. This is done by calculating the first-order energy corrections due to the relativistic correction to kinetic energy, spin-orbit coupling, and Darwin term. Thus we emphasize the role of the topological structure of the configuration space of a physical system on the quantum nature of an observable of the system.