Showing papers by "Shivaji University published in 1993"
TL;DR: A method for the preparation of Cux S thin films through chemical bath deposition from a thiosulphate acidic bath is described in this paper, where the band gap is estimated to be 2.40 eV and electrical resistivity was of the order of 10−4 ωcm.
55 citations
TL;DR: In this article, detailed experimental results on monolithicity and density of the aerogels as a function of catalysts and their concentrations, molar ratios of tetraethylorthosilicate (TEOS), ethanol (EtOH) and H2O, gel pH and gel ageing, are reported.
Abstract: As part of continuing investigation of the preparation and characterization of silica aerogels, detailed experimental results on monolithicity and density of the aerogels as a function of catalysts and their concentrations, molar ratios of tetraethylorthosilicate (TEOS), ethanol (EtOH) and H2O, gel pH and gel ageing, are reported. With large concentrations of catalysts, lower and higher aged alcogels have been found to produce opaque, cracked and highdensity silica aerogels; however, good-quality monolithic, transparent and low-density aerogels have been obtained at lower catalyst concentration (0. 01n HCl) with alcogel ageing periods between 9 and 30 days. The best quality silica aerogels, in terms of transparency and monolithicity, have been obtained using TEOS∶EtOH∶H2O in the molar ratio of 1∶5∶8.
37 citations
TL;DR: The merits and demerits of various definitions of prime and primary fuzzy ideals are discussed and new definitions are suggested in this paper, where the nil radical is defined as against the (prime) radical of a fuzzy ideal.
34 citations
TL;DR: In this article, a method for preparation of Bi2S3 thin films from a nonaqueous medium is developed, in which Bi(NO3)3 and Na2S2O3 are dissolved in acetic acid glacial and formaldehyde, respectively, to prepare equimolar (0.1 M) solutions.
28 citations
TL;DR: In this paper, Ag 2 S and CdSe electrodes were used in various charge storage configurations, such as the three-electrode storage cell, the septum cell and the redox storage cell.
26 citations
TL;DR: Uranium(VI) was quantitatively extracted with 0.01M DB-24crown-8 in nitrobenzene from 6 to 10M hydrochloric acid as discussed by the authors.
Abstract: Uranium(VI) was quantitatively extracted with 0.01M DB-24-crown-8 in nitrobenzene from 6 to 10M hydrochloric acid. From the organic phase uranium was stripped with 2M nitric acid and determined spectrophotometrically with PAR at 530 nm. Uranium(VI) was separated from a large number of elements in binary mixtures as well as from multicomponent mixtures. The method was extended to the analysis of uranium in geological samples and animal bone.
23 citations
TL;DR: In this paper, a simple chemical displacement method is used for the conversion of thin films of CdS into Ag2S and CdSe to Ag2Se, and their structural, electrical and optical properties have been studied.
17 citations
TL;DR: In this article, the chopping technique has been successfully used to enhance the adhesion of MgF2, ZnS and copper films, which is explained in terms of enhanced oxygen affinity at interface similar to that observed for aluminium and chromium.
Abstract: The chopping technique has been successfully used to enhance the adhesion of MgF2, ZnS and copper films. Chopping does not appreciably alter the adhesion of aluminium and chromium films. Chopping seems to increase the surface mobility of adatoms and prevent growth of large crystallites whereby producing more defect-free thin films because of higher relaxation leading to higher adhesion. The adhesion of chopped MgF2 and ZnS films compare well with those deposited on heated substrate and after glow discharge cleaning. The enhanced adhesion of copper films is being explained in terms of enhanced oxygen affinity at interface similar to that observed for aluminium and chromium. Chopping technique might provide a simple and cost effective process of depositing good adherent thin film coatings.
15 citations
TL;DR: A series of new polyamides and copolyamides containing aromatic sulfone ether linkages was synthesized from 4,4′-[sulfonyl-bis(4,1-phenyleneoxy-3-pentadecyl)]bisphenylamine (SPPBA) and isophthaloyl chloride (IPC), TPC, bis(4-chlorocarbonylphenyl)dimethylsilane (DMSC) by a low-temperature inter-facial polymerization technique as mentioned in this paper.
Abstract: A series of new polyamides and copolyamides containing aromatic sulfone ether linkages was synthesized from 4,4′-[sulfonyl-bis(4,1-phenyleneoxy-3-pentadecyl)]bisphenylamine (SPPBA) and isophthaloyl chloride (IPC), terephthaloyl chloride (TPC), bis(4-chlorocarbonylphenyl)dimethylsilane (DMSC) and bis(4-chlorocarbonylphenyl)diphenylsilane (DPSC) by a low-temperature inter-facial polymerization technique. SPPBA was prepared from 4,4′-dichlorodiphenyl sulfone and 4-amino-3-pentadecyl phenol derived from cashew-nut shell liquid and was characterized by spectral methods and elemental analysis, whereas the polyamides were characterized by solution viscosity, IR spectroscopy, thermogravimetric analysis, X-ray diffraction and solubility. These polyamides showed enhanced solubility in organic solvents and no weight loss below 405°C in nitrogen. The effect of pendant penladecyl substituents and silicon in the main chain of polyamides on the properties of these polymers was studied by comparing their properties with those of unsubstituted polyamides prepared from 4,4′-[sulfonylbis(4,1 -phenyleneoxy)] bisphenylamine.
14 citations
TL;DR: In this paper, the authors reported thermal power and electrical resistivity for the system Cu1+xSnxFeFe2−2xO4 from room temperature to 800 K. Hopping conduction phenomenon has been explained on the basis of localized model of electrons.
Abstract: Thermoelectric power (α) and electrical resistivity (ρ) are reported for the system Cu1+xSnxFe2−2xO4 (wherex=0·05, 0·1, 0·15, 0·2 and 0·3) from room temperature to 800 K. The compositions withx=0·05 and 0·2 exhibitn-type conduction while the compositions withx=0·1 and 0·15 showp- ton-type conduction change after 423 K. The conduction at low temperature (i.e. 400 K), it is due to polaron. Hopping conduction phenomenon for the present system has been explained on the basis of localized model of electrons. Additional localization may arise due to Sn4+ + Fe2+ stable pairs at B-site and Cu1+ + Fe3+ pair at A-site.
11 citations
TL;DR: In this article, the effect of the frequency of square wave pulses on the nature and thickness of alloyed films has been studied in depth, and it was found that a 50 Hz square wave pulse at −1.55 V versus SCE gives optimum quality of the alloyed film.
TL;DR: Eight different characterizations of semiprime fuzzy ideal are discussed and six of them are related to the fuzzy ideal described in the previous chapter.
TL;DR: A very simple column chromatographic separation method has been developed for molybdenum (VI) using poly-(dibenzo-18-crown-6) using hydrochloric acid medium and the reproducibility of the procedure is +/-2%.
TL;DR: In this paper, the authors describe variation of nucleation density and growth of these crystals as a function of concentration of feed solution, gel ageing, gel density, gel pH and intermediate neutral gel column.
Abstract: As part of our work on growth of cadmium oxalate single crystals in gels, we describe here variation of nucleation density and growth of these crystals as a function of concentration of feed solution, gel ageing, gel density, gel pH and intermediate neutral gel column. While high density and high pH gels have been found to produce opaque crystals, good quality transparent single crystals have been obtained in low density and low pH gels. It was observed that the intermediate neutral gel column and gel ageing considerably reduced the number of nucleation sites and increased the size of the crystals without affecting their quality. By concentration programming the size of the crystals increased.
TL;DR: In this article, the electrical resistivity and thermoelectric power were measured in the temperature range from 300 K to 750 K on the system Cu1+xGexFe2−2xO4 with x=005, 01, 015, 02 and 03.
Abstract: The electrical resistivity (ρ) and thermoelectric power (α) were measured in the temperature range from 300 K to 750 K on the system Cu1+xGexFe2−2xO4 with x=005, 01, 015, 02 and 03 The dependence of electrical properties with temperature showed three regions In the first region the conduction is due to impurities whereas in the second and third it is due to polaron hopping The temperature dependence ofα andρ suggests that the transport properties measured may be interpreted on the basis of polaron hopping The activation energy in paramagnetic region is found to be less than that in ferrimagnetic region This behaviour therefore can be stated to be anomalous
TL;DR: In this article, the authors have shown that the coastal belt exhibits varied degrees of seismicity from intensely seismic areas, like the Mekran coast off Pakistan, Kutch (India) and the Arakan-Yoma arcuate belt of Burma, which is a part of the global Alpine-Himalayan orogenic belt, continuing southwards into the Andaman-Nicobar island complex and the Java-Sumatra trench on the ocean floor of the advancing Indo-Australian Plate.
Abstract: Major geotectonic elements that are seismically active in the near-shore areas of the Indian subcontinent are the Mekran fault off the coast of Pakistan, the western part of the Narmada-Son lineament, the West Coast Fault off the west coast of India - a southward extension of the Cambay Rift, the Palghat Gap, the Godavari and Mahanadi grabens, transecting rather at an angle to the eastern coast of India and the Arakan-Yoma arcuate belt of Burma, which is a part of the global Alpine-Himalayan orogenic belt, continuing southwards into the Andaman-Nicobar island complex and the Java-Sumatra trench on the ocean floor of the advancing Indo-Australian Plate. The coastal belt exhibits varied degrees of seismicity from intensely seismic areas, like the Mekran coast off Pakistan, Kutch (India) and the Arakan-Yoma belt of Burma, with earthquake magnitudes of more than 8.0, while the intervening coastal areas of the Peninsular India are moderately seismic to aseismic. The remaining areas, namely, the major part of the coastal belt of Bay of Bengal in India and Bangladesh are broadly aseismic, However, the active Godavari graben and the eastern part of the coast of Bangladesh are frequented by low to moderate magnitude earthquakes. An extension of the active Arakan-Yoma belt in the Bay of BengaI in the form of the Andaman-Nicobar Island complex is highly seismic with a maximum earthquake magnitude of more than 8.0, while the Lakshadweep- Minicoy island complex, situated on the Chagos-Laccadive ridge is moderately seismic. This broad picture of coastal and marginal seismicity is corroborated by the geodynamics of the northern part of the Indo-Australian Plate. Observations along the coastal areas during historic and recent times, however, confirm the absence of significant 'tsunamis', though very mild tsunami surges have occasionally been observed aIong the coastal areas of the Bay of Bengal. No active volcanoes are known to exist in the coastal areas. Water reservoirs situated near the marginal areas of the Peninsular Shield exhibit moderate to intense seismic activities, viz. Ukai, Bhatsa, Koyna, Parambikulam, Sholayar, Idduki, and Kinnersani.
TL;DR: In this article, the variation of normalized susceptibility with temperature for CoxZn1-xFe2O4 (x = 0, 0.5, and 0.7) reveals that CoFe 2O4 contains single-domain (SD) grains.
TL;DR: In this paper, the lattice parameter increases with the increase of Ti4+ substitution while it decreases with an increase of Ge4+ substitutions in Cu1+xAxFe2−2xO4 compounds.
Abstract: The lattice parameter,a, increases with the increase of Ti4+ substitution while it decreases with the increase of Ge4+ substitution in Cu1+xAxFe2−2xO4 compounds [A=Ti4+, Ge4+Sn4+] On substitution of Sn4+,a does not vary CuFe2O4 exhibits single domain (SD) behaviour that changes to multi domain (MD) type on Ti4+ substitution On Ge4+ substitution initially all the compositions exhibit SD behaviour while forx>02 they show MD behaviour All Sn4+ substituted compositions exhibit SD behaviour The Curie temperature decreases on addition of Ti4+, Sn4+ and Ge4+ The magnetic momentnB (77 K) initially increases and then decreases with the substitution of Ti4+, Ge4+, and Sn4+ This is explained by cation distribution and reduction of Fe3+ ions
TL;DR: The main active species under the reaction conditions were found to be VOinf2sup+ and TlClinf3sup2− for the oxidant and reductant, respectively.
Abstract: The reaction between VV and TlI was studied in 4.0 mol dm−3 HCl at an ionic strength of 4.1 mol dm−3 at 25° C. The main active species under the reaction conditions were found to be VOinf2sup+and TlClinf3sup2−for the oxidant and reductant, respectively. A probable mechanism in terms of these species is given, and follows the rate law:
$$\begin{gathered} \frac{{ - d[V^V ]}}{{dt}} = \frac{{k\beta _2 \beta _5 [H^ + ]^2 [Cl^ - ]^3 [V^V ][Tl^I ]}}{{(1 + \beta _1 [H^ + ] + \beta _2 [H^ + ]^2 ) - }} \hfill \\ {\text{ }}(1 + \beta _3 [Cl^ - ] + \beta _4 [Cl^ - ]^2 + \beta _5 [Cl^ - ]^3 ) \hfill \\ \end{gathered} $$
where β2 is the cumulative stability constant of the VOinf2sup+ion, formed by stepwise protonation of the VOinf2sup+ion, and β5 that for the TlClinf3sup2−species.
Journal Article•
TL;DR: In this paper, the pre-and post-monsoon groundwater levels during 1988 and 1989 have been measured at 40 observation wells at 40 locations well distributed in the basin, and the regional transmissivity (T) values in the Basin range from 10 to 235 m 2 /day.
Abstract: Aquifer parameters have been estimated through pump tests conducted on large diameter wells at 40 locations well distributed in the basin. The pre- and post-monsoon groundwater levels during 1988 and 1989 have been measured at 40 observation wells. (1) Total groundwater input of 23.8 MCM to aquifer system consists of 23.2 MCM of recharge due to rainfall and 0.6 MCM of seepage from canal network. (2) Total output stresses include groundwater draft of 14.6 MCM from about 1300 open wells and borewells, and groundwater effluence of 9.2 MCM to the Adila stream. (3) The regional transmissivity (T) values in the basin range from 10 to 235 m 2 /day.
TL;DR: In this paper, the dc electrical conductivities of potassium vanadate, lithium vanadates, cesium vanadat, and their solid solutions are measured in the temperature range covering their transition temperature using two-probe electrode technique.
Abstract: The dc electrical conductivities of potassium vanadate, lithium vanadate, cesium vanadate, and their solid solutions potassium—lithium vanadate, potassium—cesium vanadate are measured in the temperature range covering their transition temperature using two-probe electrode technique. These ceramics show a remarkable change in conductivity in their phase transition region. The results are found to obey the conventional exponential law and the activation energy is calculated and it is found that the activation energy in the paraelectric state is higher than in ferroelectric state. The activation energy depends not only on temperature but on concentration of potassium vanadate in both solid solutions.
Die Gleichstromleitfahigkeit von Kalium-, Lithium- und Casiumvanadaten und ihren festen Losungen KLi- und KCs- Vanadat werden mittels Zweisondentechnik im Temperaturbereich der Phasenubergange gemessen. In diesen Gebieten zeigen diese Keramiken bemerkenswerte Anderungen der Leitfahigkeit. Die Leitfahigkeit folgt dem ublichen Exponentialgesetz, die Aktivierungsenergie ist im paraelektrischen Zustand groser als im ferroelektrischen. Die Aktivierungsenergie hangt nicht nur von der Temperatur, sondern auch vom K-Vanadat-Gehalt in der festen Losung ab.
TL;DR: In this article, 3.3′O-silylated derivatives of 5′-O-DMT-2′deoxynucleoside (2) were synthesized in high yield by reaction of 5''O-Silylated DMT with tert-butyl dimethylsilylchloride using sodium hydride, benzyltriethylammonlum chloride [TEBA] and a catalytic amount of dibenzo-[18]-crown-6 [DB-18-C-6] or 15''C-
TL;DR: In this article, the authors studied the reaction of N-bromo-sulphonamide in acetonitrile and in the presence of sulphuric acid and discussed the rate law and a probable mechanism involving generation of reactive bromonium ion.
TL;DR: In this paper, the thermoelectric power of vanadates of potassium, cesium and lithium and their solid solutions was measured in the temperature range covering their transition points.
Abstract: The thermoelectric power of the vanadates of potassium, cesium and lithium and their solid solutions was measured in the temperature range covering their transition points. The thermoelectric power measurement was carried out by the two-electrode technique for pellets of polycrystalline ceramic samples. The thermoelectric power increased with temperature initially, then decreased attaining a zero value at the transition temperature. As the concentration of KVO3 increased the thermoelectric power decreased for the solid solutions (K
x
− Cs1−x
)VO3, whereas the thermoelectric power increased with increase in concentration of KVO3 for the solid solutions (K
x
− Li1−x
)VO3. Vanadates of potassium, cesium, and lithium and their solid solutions showedP type semiconductor behaviour in ferroelectric state andn type semiconductor behaviour in paraelectric region.
TL;DR: In this article, the thermoelectric power of pure and aluminium oxide doped ferroelectric potassium vanadate and cesium vanadates has been determined in the temperature range covering their transition temperature.
Abstract: The thermoelectric power(s) of pure and aluminium oxide doped ferroelectric potassium vanadate and cesium vanadate have been determined in the temperature range covering their transition temperature. The thermoelectric power is found to increase linearly with temperature, attains maximum value and with further increase in temperature decreases to zero indicating transition temperature of the respective samples while it changes sign for higher temperature. The thermoelectric power of KVO3 and CsVO3 increases with increase in doping concentration of Al2O3up to 0.1 mol. %, however, it decreases with further increase in doping concentration. It is observed that pure and aluminium doped KVO3 and CsVO3 materials show p-type behaviour in ferroelectric state andn-type behaviour in paraelectric state.