Showing papers by "University of Rajasthan published in 2000"

Activation energy and crystallization kinetics of untreated and treated oil palm fibre reinforced phenol formaldehyde composites

Abstract: In this paper, oil palm fiber reinforced phenol formaldehyde (PF) treated, as well as untreated, composites have been taken for the study. The untreated sample (sample 1) contains oil palm fiber reinforced in the PF matrix, and the same fiber is treated with silane (sample 2) and with alkali (sample 3) to produce two types of treated fibers. These treated fibers were then reinforced in the matrix to produce two treated samples. Differential scanning calorimetry has been employed to study the crystallization kinetics and the energy of crystallization for all the samples. All the samples show the well-defined peaks of crystallization. In the case of silane-treated sample, double crystallization is observed. The crystallization data are analyzed in terms of a modified Kissinger’s equation to determine the activation energy. The activation energy and other crystallization parameters have also been determined using Matusita’s equation and are compared with the values obtained from other equations. It has also been found that various treatments have improved the thermal stability of the composites to different extents.

Observation of direct photons in central 158A GeV (208)P(208)b+Pb collisions

Abstract: A measurement of direct photon production in {sup 208}Pb+ {sup 208}Pb collisions at 158A GeV has been carried out in the CERN WA98 experiment. The invariant yield of direct photons in central collisions is extracted as a function of transverse momentum in the interval 0.5 1.5 GeV/c . The result constitutes the first observation of direct photons in ultrarelativistic heavy-ion collisions. It could be significant for diagnosis of quark-gluon-plasma formation.

Effect of treatment on the thermal conductivity and thermal diffusivity of oil‐palm‐fiber‐reinforced phenolformaldehyde composites

Abstract: The thermal conductivity and thermal diffusivity of oil-palm-fiber-reinforced untreated (Sample 1) and differently treated composites were measured with the transient plane source technique at room temperature and under normal pressure. All the composites were 40% oil-palm fiber by weight. The fibers were treated with alkali (Composite 2), silane (Composite 3), and acetic acid (Composite 4) and reinforced in a phenolformaldehyde matrix. The thermal conductivity and thermal diffusivity of the composites increased after treatment to different extents. The thermal conductivity of the treated fibers as well as of the untreated fibers was calculated theoretically. The model results show that the thermal conductivity of the untreated fiber was smaller than the thermal conductivity of the treated fibers. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 916–921, 2000

Glass Transition Phenomena, Crystallization Kinetics and Enthalpy Released in Binary Se100–xInx (x = 2, 4 and 10) Semiconducting Glasses

Abstract: Results of Differential Scanning Calorimetry (DSC) under non-isothermal conditions on Se 100-x In x (x = 2, 4 and 10) glasses are reported and discussed. The glass transition region has been investigated in terms of activation energy and the dependence of glass transition temperature Tg on coordination number with varying composition and heating rates. The crystallization kinetics and its dimensionality have been studied using two different models viz. Matusita and Ozawa equations. On the basis of the obtained experimental data the temperature difference T c - Tg and the enthalpy released, ΔH c , are found to be maximum and minimum, respectively, for Se 96 In 4 glass which indicate that this glass is the thermally most stable in the composition range of investigation.

Human sperm immobilization effect of Carica papaya seed extracts: an in vitro study.

Abstract: Aim: To examine if the seed extracts of Carica papaya, which showed antispermatogenic/sperm immobilization properties in animal models, could cause human sperm immobilization in vitro. Methods: Chloroform extract, benzene chromatographic fraction of the chloroform extract, its methanol and ethyl acetate sub-fractions and the isolated compounds from the sub-fractions i.e., ECP 1 & 2 and MCP 1 & 2, of the seeds of Carica papaya were used at concentrations of 0. 1%, 0. 5%, 1% and 2%. Sperm motility was assessed immediately after addition of extracts and every 5 minutes thereafter for 30 minutes. Results: There were dose-dependent spermicidal effects showing an instant fall in the sperm motility to less than 20% at 2% concentration. Isolated compounds ECP 1 & 2 were more effective inducing a motility of less than 10%. Many of the spermatozoa became vibratory on the spot. Total inhibition of motility was observed within 20 - 25 min at all concentrations of all products. Scanning and transmission electron microscopy revealed deleterious changes in the plasma membrane of the head and mid-piece of spermatozoa. Sperm viability test and the number of abnormal spermatozoa after completion of incubation suggested that the spermatozoa were infertile. The effects were spermicidal but not spermiostatic as revealed by the sperm revival test. Conclusion: The results reveal spermicidal activity in vitro of the seed extracts of Carica papaya.

Glass transition phenomena, crystallization kinetics and thermodynamic properties of ternary Se80Te20−xInx (x=2, 4, 6, 8 and 10) semiconducting glasses: theoretical and experimental aspects

Abstract: This paper presents the results of kinematical studies of glass transition and crystallization in glassy Se 80 Te 20− x In x ( x =2,4, 6, 8 and 10) using differential scanning calorimetry (DSC). Also the thermodynamic properties of these glasses in the transformation range of temperatures have been studied. Glass transition region has been investigated in terms of activation energy, dependence of glass transition temperature on coordination number with the varying composition and heating rates. The growth kinetics and its dimensionality have been investigated using three different models viz. Kissinger, Ozawa and Matusita equations. On the basis of the obtained experimental results on phase transformations in these glasses, thermodynamic parameters like entropy difference between metastable states in the glassy region, difference of Gibbs free energy, specific heat, entropy between the two phases and the enthalpy released during crystallization have been determined. On the basis of experimental observations and theoretical calculations of thermodynamic properties, it has been found that Se 80 Te 10 In 10 is the most stable glass.

Aqueous Leachate of Lantana camara Kills Water Hyacinth

Abstract: Lantana camara, a terrestrial plant, was screened for allelopathic impact on water hyacinth (Eichhornia crassipes). Water hyacinth was allowed to grow in experimental pots containing 3% aqueous leachate (w/v) of Lantana twigs. The leachate was allelopathic to the growth of water hyacinth, and killed water hyacinth after 21 days under the experimental conditions. Leachate concentrations from 1–3% of Lantana were highly toxic to water hyacinth plants. Leachate from young Lantana twigs with prickly orange, pink, and yellow flowers (multicolored) was more toxic than leachate from mature twigs. This study indicates the potential for utilization of terrestrial allelopathic species such as Lantana camara to suppress the growth of water hyacinth.

Studies on Coordination Compounds of Organotin(IV) with Schiff Bases of Amino Acids

Abstract: The present paper describes the syntheses, characterization of some new coordination compounds of organotin(IV) with Schiffbases derived by condensation of heterocyclic ketones and amino acids, viz. glycine, β-alanine, α-valine, α-isoleucine and α-tryptophan. The newely prepared compounds have been characterized by elemental analysis, conductance measurements, molecular weight determinations, infrared and nuclear magnatic resonance (1H, 13C and 119Sn NMR) spectral studies. An trigonal bipyramidal geometry has been proposed for all of the complexes. A few representative ligands and their tin complexes have also been screened for their antibacterial activities and found to be quite active in this respect.

Kinetic studies of bulk Se85-xTe15Sbx glasses with x = 0, 2, 4, 6, 8 and 10

Abstract: Results of Differential Scanning Calorimetry (DSC) under non-isothermal condition of Se 85-x Te 15 Sb x (x = 0, 2, 4, 6, 8 and 10) glasses are reported and discussed. The glass transition temperature at different heating rates and structural changes during glass transition have been determined from an empirical relation. The activation energies for crystallization have been determined from the heating rate dependence of the peak crystallization temperatures. The results have been analyzed using Kissinger's and Matusita's equations and the modified Ozawa equation for non-isothermal crystallization of materials. The variation of the glass transition temperature with composition suggests that a small amount of Sb(4 at%) leads to an increase in the chain length of Se-Te, whereas further increase in the Sb atomic percentage increases the number of Se-Te chains in the alloys. The thermal stability (T c - T g ) is found to be maximum at 4 at% Sb and suggests that this alloy can be considered as a critical composition at which the system becomes chemically ordered. Moreover, the minimum heat released during crystallization at this composition confirms the maximum stability of the alloy.

Differential scanning calorimetry studies of Se85Te15−x Pb x (x = 4, 6, 8 and 10) glasses

Abstract: Results of differential scanning calorimetry (DSC) studies of Se85Te15−x Pb x (x = 4, 6, 8 and 10) glasses have been reported and discussed in this paper. The results have been analyzed on the basis of structural relaxation equation, Matusita’s equation and modified Kissinger’s equation. The activation energies of structural relaxation lie in between 226 and 593 kJ/mol. The crystallization growth is found to be onedimensional for all compositions. The activation energies of crystallization are found to be 100–136 kJ/mol by Matusita’s equation while 102–139 kJ/mol by modified Kissinger’s equation. The Hruby number (indicator of ease of glass forming and higher stability) is the highest for Se85Te9Pb6 glass while S factor (indicator of resistance to devitrification) is highest for Se85Te7Pb8 glass at all heating rates in our experiment. Further the highest resistance to devitrification has the highest value of structural activation energy and the activation energy of crystallization is maximum for the most stable glass by both Matusita’s equation and the modified Kissinger’s equation.

Synthesis and spectroscopic studies of organotin(IV) complexes of biologically active Schiff bases derived from sulpha drugs

Abstract: The reaction of dibutyltin oxide with Schiff bases derived from sulpha drugs in 1:1 molar ratio leads to the formation of a new series of organotin(IV) complexes. An attempt has been made to probe their structure on the basis of UV, IR, NMR (1H,13C and 119Sn) and Mossbauer spectral studies. A few representative compounds have also been screened for bactericidal activity and found to be quite active in this respect. Copyright © 2000 John Wiley & Sons, Ltd.

Three-pion interferometry results from central Pb+Pb collisions at 158A GeV/c.

Abstract: Three-particle correlations have been measured for identified {pi}{sup -} from central 158A GeV Pb+Pb collisions by the WA98 experiment at CERN. A substantial contribution of the genuine three-body correlation has been found as expected for a mainly chaotic and symmetric source.

Repeated vas occlusion and non-invasive reversal with styrene maleic anhydride for male contraception in langur monkeys

Abstract: The feasibility of a spacing method for contraception, using Styrene Maleic Anhydride (SMA) as a vas occlusive agent, has been assessed in male langur monkeys. The vas deferens of 6 animals were occluded with 60 mg SMA in 120 microL DMSO. After 150 days, the occlusion was reversed by a technique which involved palpation, percutaneous electrical stimulation, forced vibratory movement, suprapubic percussion and per-rectal digital massage of the vas segments. The vas deferens were then re-occluded with SMA and reversed by the non-invasive method after three consecutive azoospermic samples. The second vas occlusion resulted in uniform azoospermia after the third ejaculation and reversal caused the reappearance of spermatozoa in the semen to severe oligozoospermic levels in the first two ejaculations and rising to normospermia in the subsequent ejaculations. Ultrastructure of the spermatozoa by SEM and TEM and sperm function tests revealed that the spermatozoa had recovered normal morphology. Vas morphology also regained a normal pseudostratified columnar epithelium containing basal and principal cells. The results suggest that the SMA-based spacing technique for male contraception could be extrapolated to the human by use of no-scalpel injection and non-invasive reversal.

Effective thermal conductivity of three-phase styrene butadiene composites

Abstract: Transient plane source technique was used for the simultaneous measurement of thermal conductivity and thermal diffisivity of three-phase styrene butadiene rubber composites. Two series of styrene butadiene rubber composites were studied, having natural rubber as a variable filler in both the composites along with 10 phr of silica and clay, respectively. The measurements were done at room temperature and normal pressure. The experimental results show that there is a small variation in the thermal conductivity of both the composites with the filler (NR) fraction. It is interesting to note that the thermal conductivity shows a sharp decrease at 10 phr filler loading and then increases. The comparative study of these composites shows that the conductivity as well as the diffusivity of the silica reinforced composites is larger than that of the clay composites. The thermal conductivity of the filler NR has been evaluated using the Agari model. It has also been found that the composite with 40 phr of NR has the maximum thermal conductivity. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1799–1803, 2000

Fertility Inhibitor Heterobimetallic Complexes of Platinum(II) and Palladium(II): Synthetic, Spectroscopic and Antimicrobial Aspects.

Abstract: Synthetic, spectroscopic and antimicrobial aspects of some fertility inhibitor heterobimetallic complexes have been carried out. These heterobimetallic chelates [M(C5H5N3)2M2'(R)4]Cl2 (M = Pd or Pt and M' = Si, Sn, Ti and Zr) have been successfully synthesinzed via the reaction of M(C5H7N3)2Cl2 with group four or fourteen dichlorides in 1:2 stoichiometric proportions. The products were characterized by elemental analyses, molecular weight determinations, magnetic susceptibility measurements, conductance, and IR multinuclear NMR and electronic spectral studies. A square planar geometry has been suggested for all the complexes with the help of spectral data. Conductivity data strongly suggest that chlorine atoms are ionic in nature due to which complexes behave as electrolytes. All the complexes have been evaluated for their antmicrobial effects on different species of pathogenic fungi and bacteria. The testicular sperm density, testicular sperm morphology, sperm motility, density of cauda epididymal spermatozoa and fertility in mating trails and biochemical parameters of reproductive organs have been examined and discussed.

Clonal propagation of Acacia catechu Willd. by shoot tip culture

Abstract: A method is described for in vitromicropropagation through shoot apices of Acaciacatechu Willd., a semi-arid tree valued for Katha (atanin-like substance obtained from red heart wood of10–20 year old trees) and timber. Explants wereexcised from 15-days-old in vitro grownseedlings raised from superior seed stocks. Shoot budinduction from shoot apex explants was observed onMurashige and Skoog's (MS) [12] medium containingvarious growth regulators. A maximum of 12 shoots wasobtained on MS medium supplemented with 1.5 mg/l 6-benzylaminopurine (BAP) and 1.5 mg/l kinetin.Well-developed shoots (3–4 cm long) were rooted on \(\frac{1}{4}\) strength MS medium with 3.0 mg/l indole-3-acetic acid (IAA) and sucrose 1.5%. In vitro regenerated plantlets of A. catechu were transferred to field conditions.

Petrology of the Indian eucrite Piplia Kalan

Abstract: Piplia Kalan is an equilibrated eucrite consisting of 60-80 vol.% lithic clasts in a subordinate brecciated matrix. Ophitic/subophitic lithic clasts fall into two groups: finer-grained lithology A and coarser-grained lithology B. Very fine-grained clasts (lithology C) also occur and originally were hypocrystalline in texture. The variety of materials represented in Piplia Kalan suggests cooling histories ranging from quenching or fast crystallization to slower crystallization. Despite textural differences, clasts and matrix have similar mineral and bulk compositions. Thus. Piplia Kalan is probably best classified as a genomict breccia that could represent fragments of a single lava flow or shallow intrusive body, including fine-grained or glassy outer margin and more slowly cooled coarser-grained interior. Piplia Kalan displays evidence of an early shock event, including brecciated matrix and areas of lithic clasts that contain fine-grained, equigranular pyroxene between deformed feldspar laths. The meteorite also displays evidence of at least one episode of thermal metamorphism: hypocrystalline materials are recrystallized to hornfelsic textures and the matrix has a nonporous texture similar to those of eucrites that were affected by post-brecciation heating. Veins of brown glass transect both lithic clasts and brecciated matrix and indicate a second, post-metamorphism shock event.

Montmorillonite Catalysed Synthesis of Novel Spiro[3H-Indole-3,3′- [3H-1,2,4] Triazol]-2(1H) Ones in Dry Media under Microwave Irradiation

Abstract: A new route for the one pot synthesis of novel spiro[3H-indole-3,3′-[3H-1,2,4] triazol]-2 (1H) ones utilizing 3-arylimino-2H-indol-2-ones (3) and thiosemicarbazide (4) as starting material under mi...

Tilted Bianchi Type I Models with Heat Conduction Filled with Disordered Radiations of Perfect Fluid in General Relativity

Abstract: In this paper, we have investigated some tilted Bianchi Type I models with heat conduction filled with disordered radiation of perfect fluid. To get a determinate solution, we have assumed a condition A =(BC) n between metric potentials. Alternatively we have discussed the case A=(BC) 1/3 for which tilted nature of the model is preserved. The various and geometrical features with singularities in the models are also discussed.

Effects of Organoantimony(III) Compounds of Sterically Hindered Bifunctional Tetradentate Ligands on the Reproductive System of Male Rats

Abstract: The antifertility activity of organoantimony(III) complexes PhSb[RC(NC6H4S)CH2(NC6H4S)CR′] {R' = CH3 (R1) and R = R' = CF3 (R2)} derived from corresponding sterically hinlered bifuinctional tetradentate ligands in the male rats was determined. The administration of compounds R1 and R2 at the dose level of 20 mg/kg. b. wt. siignificantly reduced the weights of testes and epididymides. Auxiliary glands showed a significant reduction after the treatment of compound R1 only. Treated animals showed a notable depression of spermatogenesis. The preleptotene spermatocytes were decreased by 76.19 and 47.06; the secondary spermatocytes by 87.4% and 54.87337; and the step-19 spermatids by 72.9 and 46.77% respectively, following the compound R1 and R2 treatment. Reduced sperm count and motility resulted in 100% negative fertility in both the treated groups. A significant fall in the content of various biochemical parameters of eproductive tissues was observed after R1 and R2 treatment in comparison to controls.