Showing papers by "Kuvempu University published in 2001"

Flexural strength of heat-polymerized polymethyl methacrylate denture resin reinforced with glass, aramid, or nylon fibers.

Abstract: Statement of problem. Despite the favorable properties of conventional PMMA used as a denture base material, its fracture resistance could be improved. Purpose. This in vitro study was performed to determine whether the flexural strength of a commercially available, heat-polymerized acrylic denture base material could be improved through reinforcement with 3 types of fibers. Material and methods. Ten specimens of similar dimensions were prepared for each of the 4 experimental groups: conventional acrylic resin and the same resin reinforced with glass, aramid, or nylon fibers. Flexural strength was evaluated with a 3-point bending test. The results were analyzed with a 1-way analysis of variance. Results. All reinforced specimens showed better flexural strength than the conventional acrylic resin. Specimens reinforced with glass fibers showed the highest flexural strength, followed by aramid and nylon. Conclusion. Within the limitations of this study, the flexural strength of heat-polymerized PMMA denture resin was improved after reinforcement with glass or aramid fibers. It may be possible to apply these results to distal extension partial denture bases and provisional fixed partial dentures.

Interpenetrating polymer networks based on polyol modified castor oil polyurethane and poly(2-hydroxyethylmethacrylate): Synthesis, chemical, mechanical and thermal properties

Abstract: Interpenetrating polymer networks (IPNs) of glycerol modified castor oil polyurethane (GC-PU) and poly[2-hydroxyethylmethacrylate] (PHEMA) were synthesized using benzoyl peroxide as initiator and N,N-methylenebis acrylamide as crosslinker. GC-PU/PHEMA interpenetrating polymer networks were obtained by transfer moulding. These were characterized with respect to their resistance to chemical reagents and mechanical properties such as tensile strength, per cent elongation and shore A hardness. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were undertaken for thermal characterization. The changes in NCO/OH ratio and GC-PU/PHEMA composition on the properties of the IPNs were studied.

Tamoxifen citrate induced sperm shape abnormalities in the in vivo mouse.

Abstract: The genotoxic potential of an anticancer drug, tamoxifen citrate, was studied in the in vivo mouse system using the sperm abnormality assay. Sperms of Swiss albino mice were examined after 5 weeks of repeated administration of different doses of the drug for 10 days. The doses used were 0.1, 0.2, 0.4 and 0.8 mg/kg b.w. per day. Statistically significant sperm abnormalities revealed the genotoxic potency of this drug.

Effect of temperature and relative humidity on spinning behaviour of silkworm (Bombyx mori.L)

Abstract: The rate of spinning of silkworm larva (Bombyx mori.L) was slow at 22 degrees C and fast at 38 degrees C. The time taken for completion of cocoon was longest at 98 +/- 2% and least at 40 +/- 2% RH. However, good quality cocoons were spun at 22 degrees C and 65 +/- 5% RH, hence it would be advantageous to maintain this temperature and relative humidity at the time of cocoon spinning in the case of CB race of silkworm.

Synthesis And Pharmacological Screening Of Some Novel Naphtho (2, 1-b) Furo-Pyrazolines, Isoxazoles And Isoxazolines

Abstract: 2-Acetylnaphtho [2,1-b] furan 1 was reacted with various aromatic aldehydes in presence of alkali, to produce corresponding chalcones 2a-i. These were converted into l-phenyl-3- (naphtho [2,l-b] fur-2yl-5- aryl-2-pyrazolines 3a-i and 1-(4-nitrophenyl)-3-(naphtho [2,1-b] fur-2yl-5-aryl-2-pyrazolines 4a-i by treatment with phenyl hydrazine and 4-nitrophenyl hydrazine respectively. The reaction of chalcones 2a-i with hydroxylamine hydrochloride in presence of sodium acetate in glacial acetic acid produced 3- (naphtho [2,1-b] fur-2yl)-5-aryI-2-isoxazole5a -i, whereas similar reaction in the presence of potassium hydroxide yielded 3-(naphtho [2,l-b] fur-2yl)-5-aryl-2-isoxazolines 6a and 6e. All the compounds have been characterized by elemental analysis and spectroscopic data. These novel biheterocyclic compounds have been screened for antibacterial, antifungal, anthelmintic and analgesic activities. The compound 4e showed promising antimicrobial activity, some of the compounds exhibited moderate antibacterial and antifungal activity. The only compound that showed maximum analgesic activity is 3d. Anthelmintic activity revealed the compounds 4e, 5b and 5i were as active as the standard drug.

Synthesis and spectroscopic investigation of tetranitro-, tetraamino-, tetrahydroxy-, and tetracyanophthalocyanineiron(iii) chloride

Abstract: The synthesis of peripherally tetrasubstituted phthalocyanineiron(III) chloride derivatives, (R)4PcFe(III)Cl (R=NO2, NH2, OH. and CN at the positions 2,9,16,23 or 1,8,15,22) is described. The complexes were characterized by magnetic susceptibility measurements, electronic and infrared spectra and X-ray powder diffraction patterns. The effects of substituents at the periphery, and the solvents used on the electronic spectra are discussed. The Q band of the electronic spectra for the symmetrically functionalized derivatives are red-shifted compared to that of unsubstituted PcFeCI. The substituents at positions 2,9,16,23 are more effectively involved, in the extension of the π-cloud delocalization than at the positions 1,8,15,22. The LMCT transitions superimposed on the Q band are found to be shifted to an intermediate region of 414–497 nm depending on the basicity of the solvent. The sharp IR signals of the C-H bond and metal-ligand vibrations appears to be diminished for the 2,9,16,23-substituted derivativ...

Inducible protective processes in animal systems: VIII. Enhancement of adaptive response by nicotinamide.

Abstract: The molecular mechanism of the adaptive response or inducible DNA repair process has not been clearly demonstrated in eukaryotic systems. The involvement of poly(ADP-ribose) polymerase (PARP), a DNA repair enzyme has been reported in the adaptive response (Shadley and Wolff, 1987; Wiencke, 1987). Hence, the present studies were undertaken to understand the role of PARP in ethyl methanesulfonate (EMS)-induced adaptive response in mouse bone marrow cells by employing the inhibitor of this enzyme, nicotinamide. Inter-, pre- and post-treatments of nicotinamide with EMS were made. The results have revealed that there is a reduction in the frequencies of chromosomal aberrations compared with combined or challenge treatment at the different recovery times tested. These results are discussed with reference to the enhancement of the adaptive response by nicotinamide in mouse bone marrow cells.

Oxidation of 3‐(3,4‐dihydroxy phenyl)‐l‐alanine (levodopa) and 3‐(3,4‐dihydroxy phenyl)‐2‐methyl‐l‐alanine (methyl dopa) by manganese(III) in pyrophosphate media: Kinetic and mechanistic study

Abstract: Manganese(III) (Mn(III)) has been stabilized in weakly acidic solution by means of pyrophosphate and the nature of the complex was elucidated spectrophotometrically Stoichiometry of Mn(III)-oxidation of levodopa and methyl dopa in pyrophosphate medium was established in the pH range 25–40 by iodometric and spectrophotometric methods The reaction shows a distinct variation in kinetic order with respect to [Mn(III)], a first-order dependence in the pH range 19–26, decreasing to fractional order above pH 3 Other common features include first-order dependence on [dopa], positive fractional order dependence on [H+], and inverse first-order dependence on [Mn(III)] in the pH range studied The effects of varying ionic strength and solvent composition were studied Added ions such as SO42− and ClO4− alter the reaction rate, probably due to the change in the formal redox potential of Mn(III)–Mn(II) couple because of the changes in coordination environment of the oxidizing species Evidence for the transient existence of the free radical intermediate is given Cyclic voltametric sensing of levodopa and methyl dopa has ruled out the formation of dopaquinones as oxidation products in the pH range studied Activation parameters have been evaluated using the Arrhenius and Erying plots Mechanisms consistent with the kinetic data have been proposed and discussed These studies are expected to throw some light on dopa metabolism © 2001 John Wiley & Sons, Inc Int J Chem Kinet 33: 449–457, 2001

Problems & prospects of rural libraries

Abstract: Studies the extent of availability and accessibility of information in rural libraries based on the data collected through questionnaire from sixteen rural libraries of Shimoga district in Karnataka State. All the sixteen rural libraries do not have mass media to provide up-to-date information and none of the libraries has independent building to bring the sources, services and users under the same root.

Decay energy of 55Fe from its inner bremsstrahlung spectrum

Abstract: Several measurements of decay energy using the inner Bremsstrahlung spectrum (IB) due to radiative electron capture in 55Fe has been made. But the results are not uniform. Hence another attempt has been made at the same. Experimental data was obtained with a 4.445 cm. dia × 5.08 cm thick Nal (Tl) detector. It was subjected to suitable statistical treatment and various corrections using Liden and Starfelt procedure. The corrected spectrum agrees well with the Glauber and Martin theory for 1s electron capture beyond 100 keV. From the Jauch plot, the decay energy of 232.36±0.64 keV was obtained.

Periodical literature of plant and cell physiology: a citation analysis study to determine obsolescence factors and patterns

Abstract: Citation analysis was applied to the data of the Journal Plant and Cell Physiology of the year 1998. The distribution of citation frequencies was statistically tested and found be negative exponential distribution type. The obsolescence factors were determined. The average half-life literature was found to be of 6.2 years. Brooks technique of calculating AAF=a was applied to determine its applicability for the literature. The values of "a" was found to be 0.85 and the utility factors were calculated and found to be 6.64.