http://nopr.niscair.res.in/handle/123456789/81 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/219 Title: Predicting heats of fusion of nitramines <br/> <br/>Authors: Keshavarz, M H <br/> <br/>Abstract: This paper describes a new procedure to predict heats of fusion of nitramines as an important class of energetic materials. This method can be applied for linear and cyclic nitamines. The number of oxygens and two specific structural parameters of nitamines would be needed in the new method. Heats of fusion predicted using the method described herein have a root mean square (rms) deviation of 3.71 kJ/mol from 48 measured values (corresponding to 22 molecules). The new method is also applied to two nitramines, i.e., 1,3,5,7,9,11-hexanitro-1,3,5,7,9,11-hexaazacyclododecane and 1,3,3-trinitroazitidine (TNAZ), which gives comparable results with respect to experimental values. <br/> <br/>Page(s): 386-390 http://nopr.niscair.res.in/handle/123456789/218 Title: Preparation, characterization and physical properties of Mg-Zn ferrites <br/> <br/>Authors: Bammannavar, B K; Naik, L R; Pujar, R B; Chougule, B K <br/> <br/>Abstract: Polycrystalline nano-sized ferrites with the general chemical formula Mg₁₋x Znx Fe₂O₄z (where x = 0.1, 0.2, 0.3, 0.4 and 0.5) have been prepared from a simple polymer matrix based precursor solution. The solution was composed of metal nitrates with polymer PVA and Sucrose. Thermolysis of the precursor mass at about 773 K resulted in the oxide phase. Sam-ples of ferrites were characterized by various experimental techniques including scanning electron microscopy (SEM), X-ray diffraction studies, IR studies and VSM (vibrating sample magnetometer) analysis. The variation of resistivity with tempera-ture shows the break at Curie temperature, indicating the transition from ferrimagnetism to paramagnetism however; the ef-fects of porosity on electric and magnetic properties of the ferrite samples are also discussed. <br/> <br/>Page(s): 381-385 http://nopr.niscair.res.in/handle/123456789/217 Title: Synthesis, characterization and studies of phase transition in GeSe single crystals grown using different transporting agents <br/> <br/>Authors: Solanki, G K; Deshpande, M P; Agarwal, M K <br/> <br/>Abstract: The paper reports growth of germanium monoselenide (GeSe) single crystals by vapour phase technique using different transporting agents. The single crystallinity and composition of the grown samples have been verified through transmission electron microscopy (TEM) and energy dispersive analysis of X-rays (EDAX) respectively. In order to look for the possibility of phase transition, resistivity measurements have been carried out in different temperature ranges starting from 10 K. The results have indeed shown discontinuities both in the low temperature range as well as in the high temperature range. Such discontinuities in the past have been associated with possible phase transitions in GeSe. A possible explanation for the discontinuities is provided and the implications have been discussed. <br/> <br/>Page(s): 373-380 http://nopr.niscair.res.in/handle/123456789/216 Title: Capillary water absorption of self-compacting concrete under different curing conditions <br/> <br/>Authors: Turk, Kazim; Caliskan, Sinan; Yazicioglu, Salih <br/> <br/>Abstract: This paper reports an experimental study carried out to investigate the influence of addition of pozzolanic materials and curing regimes on the mechanical properties and the capillary water absorption (sorptivity) characteristics of self-compacting concrete (SCC). Portland cement (PC) concrete and two types of SCC, SCC-I with fly ash (30% FA/70% PC) and SCC-II with silica fume (10% SF/90% PC), specimens were prepared and cured in three different curing conditions (standard 20°C water, sealed and air cured) for the periods of 3, 7, 14 and 28 days. At the end of each curing period, compressive and tensile strengths and ultrasonic pulse velocity (UPV) values were determined; sorptivity coefficents were determined at 28 days. The results indicated that SCC-II specimens gave higher compressive and tensile strength and lower sorptivity coefficient values than those of corresponding SCC-I and PC concrete specimens, regardless of curing regimes and age of concrete. The results also showed a good correlation between the strength development of concrete and its sorptivity, i.e., as the compressive and tensile strengths increased due to the hydration, the sorptivity coefficients decreased significantly. <br/> <br/>Page(s): 365-372