Showing papers by "Minia University published in 1994"
TL;DR: The Van der Pauw method is one of the most effective and widely used methods of the four-probe mode of determining the resistivity of materials in the form of thin films.
146 citations
TL;DR: It is suggested that PACAP and PGE2 may modulate the release of GH in cattle by producing a synergistic effect that is not clear when compared with GRF alone.
57 citations
TL;DR: In this paper, the effects of deposition time (10-30 min) and substrate temperature (300-500 °C) on polycrystalline ZnS films of cubic phase were studied.
57 citations
TL;DR: This paper showed that Ni(CH3COO)2·4H2O decomposes completely at 500°C, giving rise to a mixture of Nio and NiO.
Abstract: Thermogravimetry, differential thermal analysis, X-ray diffractometry and infrared spectroscopy showed that Ni(CH3COO)2·4H2O decomposes completely at 500°C, giving rise to a mixture of Nio and NiO. The results revealed that the compound undergoes dehydration at 160°C and melts at 310°C. The water thus released hydrolyses surface acetate groups, acetic acid being evolved into the gas phase. At 330°C, the anhydrous acetate is converted into NiCO3, releasing CH3COCH3 into the gas phase. The carbonate subsequently decomposes (at 365°C) to give NiO(s), CO2(g) and CO(g). On further heating up to 373°C, a mixture of Nio and NiO is formed. Other gas-phase products were detected at 400°C, viz. CH4 and (CH3)2CH=CH2, which were formed in surface reactions involving initial gas-phase products. Non-isothermal kinetic parameters (A and ΔE) were calculated on the basis of temperature shifts experienced in the various decomposition processes as a function of heating rate (2–20 deg·min−1).
41 citations
TL;DR: In this article, the thermal decomposition of calcium citrate tetrahydrate in dynamic air or dry nitrogen has been studied thoroughly and the results show that Ca3(C6H5O7)2·4H2O dehydrates in two successive steps at 60-140°C and 140-190°C each involving release of two moles of water.
41 citations
TL;DR: In this article, the authors used infrared spectroscopy and X-ray diffractometry to characterize the surface and texture properties of Y 2 O 3 residues, which were then subjected to surface-and texture investigations.
38 citations
TL;DR: In this article, the thermal decomposition of cobalt oxalate dihydrate was thoroughly investigated in dynamic air or nitrogen, where thermal events occurring throughout the decomposition range (room temperature to 600 °C) were monitored by means of thermogravimetry, differential thermal analysis (DTA) and differential scanning calorimetry (DSC).
36 citations
TL;DR: In this paper, the thermal decomposition of the hydrated acetate and oxalate of praseodymium in air was analyzed using thermal and differential thermal analysis, infrared spectroscopy, X-ray diffractometry and surface area measurements.
31 citations
TL;DR: In this paper, the morphological and textural changes accompanying the decomposition processes of magnesium citrate 14-hydrate have been examined by scanning electron microscopy, using spectroscopy and X-ray diffractometry.
25 citations
TL;DR: In this article, the authors showed that thiosemicarbazide can react with 2,3-dichloro-5,6-dicyano-1,4-naphthoquinone (DCHNQ) to yield 3-amino-5-arylthiadiazoles.
24 citations
TL;DR: In this article, the results revealed that the compound dehydrates in two steps at 130 and 180°C, and recrystallizes at 210°C and at 334°C the anhydrous acetate releases gas phase CH3COCH3 to give La2(CO3)3 residue.
Abstract: Thermogravimetry, differential thermal, X-ray diffraction and infrared spectroscopy analyses showed La(CH3COO)3·1.5H2O to decompose completely at 700°C yielding La2O3. The results revealed that the compound dehydrates in two steps at 130 and 180°C, and recrystallizes at 210°C. Water thus produced hydrolyzes surface acetates (at 310°C), releasing acetic acid into the gas phase. At 334°C, the anhydrous acetate releases gas phase CH3COCH3 to give La2(CO3)3 residue, which decomposes to La2O2(CO3) via the intermediate La2O(CO3)2. On further heating up to 700°C, La2O3 is formed. IR spectroscopy of the gaseous products indicated a chemical reactivity at gas/solid interfaces formed throughout the decomposition course. As a result, CH3COCH3 was involved in a surface-mediated, bimolecular reaction, releasing CH4 and C4H8 (isobutene) into the gas phase.
TL;DR: An alternative datum transformation approach, which belongs essentially to the well known polynomial methods, is presented in this paper, where problems associated with data transformation are discussed and the concept of the developed approach is discussed.
Abstract: An alternative datum transformation approach, which belongs essentially to the well known polynomial methods, is presented. Problems associated with datum transformation are mentioned. The concept of the developed approach is discussed. A comparison between the developed approach and similarity transformation based datum-shifts for Egypt is carried out. The results show that the developed approach gives significantly better accuracy.
TL;DR: The reaction of 1,2,4-triazino[5,6-b]indole-3-thione with tetracyanoethylene (TCNE) afforded the disulfide 6 the tricyanovinylation product 8 and thiazolotriazinoindole 11 as discussed by the authors.
TL;DR: In this paper, the Schottky barrier parameters of the cell in the dark and under different monochromatic light intensities have been determined by a low frequency differential capacitance method.
TL;DR: In this paper, the 1H n.m.r and i.r. spectra showed the ligands to be in the keto form and the results indicate slight semiconducting behaviour.
Abstract: Mercury(II) complexes of some pyrimidine derivatives were prepared and characterized by elemental analysis and spectral measurements. The 1H n.m.r and i.r. spectra show the ligands to be in the keto form. Thermal analysis and electrical conductivity measurements of the complexes were investigated in the temperature range 30–250°C. The results indicate slight semiconducting behaviour. The disparity in the activation energy values, ΔE as calculated from the slopes of the linear parts of the electrical conductivity curves is due to the difference in the concentration of the imperfections contained in the different types of the complexes.
TL;DR: In this paper, the chemical constituents of the aerial parts of pyrethrum santolionoides were investigated and six new sesquiterpene lactones (two 2,3-secogermacranolides and four germacranols) were discovered.
TL;DR: In this article, the influence of agitation, particle diameter and mass of adsorbent on the external mass transfer coefficient is discussed and the computed values correlate with the dimensionless function Sh/Sc 1/3.
Abstract: The influence of agitation, particle diameter and mass of adsorbent on the external mass-transfer coefficient is discussed. The computed values correlate with the dimensionless function Sh/Sc 1/3 . It has been found that Sh/Sc 1/3 varies linearly with the variables studied and may be correlated with system variables via the equation Sh/Sc 1/3 = A(variable) B
TL;DR: It is suggested that GH-releasing peptide (GHRP) induced GH release in cattle via a direct action on anterior pituitary cells in vitro through a dose-related manner and was significantly more potent than that of GHRP alone.
Abstract: The effect of His-D-Trp-Ala-Trp-D-Phe-Lys-NH2(GHRP) on growth hormone (GH) release from cultured bovine anterior pituitary (AP) cells was studied in vitro with the interactive effects of GH-releasing factor (GRF: hpGRF (1-29)-NH2) and somatostatin (SRIF). The AP cells (5×104cells per well) were incubated with media, and the media were changed 3 days after plating. After 3.5 days in culture, cells were incubated for 2h with the peptides. GHRP stimulated GH release from cultured cells in a dose-related manner. At doses from 10-11to 10-7M GHRP, the amount of GH released was significantly greater than the controls (P<0.05 to P<0.001). The amounts of GH released at lower doses of GHRP (10-14to 10-12M) were not significantly different from the controls. GH concentrations after treatment with 10-11and 10-7M GHRP were 3.98±0.27 and 4.81±0.16ng/ml, respectively. In experiments performed similarly, the 10-7M GHRH, GHRP, and combined treatment with GHRP plus GHRH increased GH 126, 57, and 139%, respectively (P<0.001). The GH releasing effects of either GHRH alone or GHRP plus GHRH were significantly more potent than that of GHRP alone (P<0.001). The additive effect was not significant when compared with GHRH alone. GH release induced by either GHRH or GHRP was significantly inhibited by SRIF (P<0.01) compared with the untreated control. The inhibitory effect of SRIF in combined treatment with GHRP plus GHRH was significantly less than that of SRIF with GHRH or with GHRP (P<0.01). The present study suggests that GH-releasing peptide (GHRP) induced GH release in cattle via a direct action on anterior pituitary cells in vitro.
TL;DR: In this article, the authors deal with a study of natural radioactivity of various samples of granite rocks from the Umm Gidri area located in North Eastern Desert in Egypt.
TL;DR: In this paper, the physical properties of CdTe thin films formed by vacuum evaporation techniques onto glass substrates were studied as a function of the processing conditions, and the structure of these thin films was examined using an X-ray diffraction (XRD) technique.
Abstract: The physical properties of CdTe thin films formed by vacuum evaporation techniques onto glass substrates were studied as a function of the processing conditions. The structure of CdTe films was examined using an X-ray diffraction (XRD) technique. The films were polycrystalline and cubic; they were grown with the (1 1 1) plane parallel to the substrate. The lattice constant (a = 0.6470 nm) was found to be smaller than that for a stoichiometric samples. This indicates the presence of residual compression stresses or excess Cd in substitutional sites. The crystallite size (10–72 nm) was found to increase with increasing substrate temperature (300–520 K). The films contained free Te which was varied with the substrate temperature. The variation of transmission within the wavelength range from 500 to 1000 nm was also investigated. It showed a band edge at about 1.5 eV. The variations of conductivity and carrier concentration with temperature were investigated. The conductivity data in the low-temperature region were analysed for variable range-hopping conduction on the basis of Mott's model. The analysis of the high-temperature conductivity data was based on Seto's model of thermionic emission. On the other hand, it was found that excess Cd increases the conductivity. However, the density of trap states near the Fermi level N(EF), was proportional to the Cd content.
TL;DR: In this article, the synthesis of seven new complexes of mixed ligands and metals was reported, whose stoichiometries (metals:ligands) were found to be 1∶3, 2∶2 and 3∵2 corresponding to FeL12L2H, M2L1L2 and M′M2L 1L2, respectively (where M′ = Cu2+, M = Cu 2+, Co2+ or Ni2+; HL1 = Methyl Red; H2L2 = Alizarin Yellow R).
Abstract: The synthesis of seven new complexes of mixed ligands and metals are reported. Their stoichiometries (metals:ligands) were found to be 1∶3, 2∶2 and 3∶2 corresponding to FeL12L2H, M2L1L2 and M′M2L1L2, respectively (where M′ = Cu2+, M = Cu2+, Co2+ or Ni2+; HL1 = Methyl Red; H2L2 = Alizarin Yellow R). The complexes were characterized by elemental analysis, infrared and Nujol mull electronic spectra and magnetic moment measurements. The results of the electrical conductivity studies for the prepared complexes in the solid state (using compressed tablets) indicated reasonable semiconducting properties. The magnitude of these values, logσ291 lay between −5.46 and −8.67, resulting from the structure and nature of the substituent of the two mixed ligands as well as the high metallic content of their complexes.
TL;DR: A special technique for isolating aquatic Pythium spp.
TL;DR: In this article, the moisture content, pH value, thiobarbituric acid (TBA) value, water holding capacity, and microbiological examination of beef during frozen storage at times up to six months were determined in order to evaluate different packaging materials and treatments.
TL;DR: In this paper, the surface area and pore structure of K + -contamined NH 4 MnO 4 was estimated using α s -method and standard adsorption data determined on a local reference material (calcination product of the permanganate at 1273 K for 20 h).
Abstract: Nitrogen sorption isotherms have been determined at 77 K on pre-characterised MnO x bulk samples obtained by calcination at 423-873 K of K + -contamined NH 4 MnO 4 . The isotherms have been analysed for estimating the surface area and pore structure of the test samples adopting the α s -method and standard adsorption data determined on a local reference material (calcination product of the permanganate at 1273 K for 20 h). The most prominent result of the present investigation is that the presence of K + leads to the formation of a channel-structured KMn 8 O 16 bulk phase at 573 K and the following consequent textural modifications: (i) a considerable increase in the surface area to 205 m 2 /g, (ii) the construction of a uniform pore system consisting of energetically uniform internal surfaces of considerable area (=92 m 2 /g). The results also reveal that the test surfaces generally exhibit a low heat towards N 2 adsorption
TL;DR: In this paper, the activity size distributions of the natural radionuclides 7 Be, 210 Pb and 40 K were determined in the open air by means of γ spectroscopy.
TL;DR: Pythium marsipium was isolated by baiting irrigation pond water from Osaka, Japan with satsuma mandarin rind with new information about the fungus and a method for obtaining sexual structures is presented.
TL;DR: The positivity of anticardiolipin Ab isotypes both IgM and IgG was high in children with ESRD on haemodialysis, and these antibodies should be considered as markers of high risk for fistula thrombosis.
Abstract: IgG and IgM anticardiolipin antibody (Ab) concentrations were determined in serum samples of 48 children with end-stage renal disease (ESRD) on haemodialysis using ELISA technique in an attempt to analyse their possible role in the occurrence of thrombosis of the vascular access. Ten normal healthy children were studied as a control group. The positivity of anticardiolipin Ab isotypes both IgM and IgG was high in children with ESRD on haemodialysis. Children with positive anticardiolipin Ab had significantly higher incidence of prior thrombosis of vascular access. Also, these antibodies should be considered as markers of high risk for fistula thrombosis.
TL;DR: In this paper, the optimum conditions for the best performance of magnesium-selective PVC membrane electrodes based on 1,2-bis(diarylphosphine oxide)benzene as a new class of neutral carriers were investigated.
TL;DR: In this paper, the authors investigated reductive events in the decomposition course of ammonium paratungstate (APT) and concluded that a pre-calcination of APT-containing materials might develop upon reduction to monolayer-type W0 catalysts.