Crystal structure changes in Ni3Al and its anomalous temperature dependence of strength

The existence of a structural transformation in Ni3Al alloys established earlier through X-ray diffraction, dilatometry and TEM investigations are summarised. The results obtained are discussed through a model proposed. The L12 structure appears to transform to another L12 or to a DO22 structure during heating. Such a transformation starts at around 700°C and seems to complete around 1100°C. In the temperature range 700-1100°C both phases coexist. This causes a tetragonal distortion of the L12 lattice giving rise to a tweed morphology in TEM observations. The flow stress studies indicate that the anomalous strengthening behaviour is not only due to the dislocation kind of mechanism as proposed in the literature but also due to the structural changes noticed in this work

Service quality gap analysis in private sector bank - a customer perspective

The present study evaluates the customer perceptions of service quality in selected private sector banks. Data was collected from 200 customers of ICICI and CUB using structured questionnaire. Gap analysis and Multi regression were used fro analysis of data. The result shows that the dimension of service quality such as Empathy and Accessibility has more gap, as the customer expectations are high to their perceived service. The result also indicates that Empathy-Reliability-Assurance positively influences the service quality. The study implies that bank should reduce the service gap to deliver superior quality of service to retain existing customers as well as to attract new customers.Service quality, Service Gap, Multi Regression

Thermal evidence for the structural instability in Ni3 Al alloys

The thermal expansion coefficient (¿) and calorimetric data were obtained as a function of temperature in order to clarify some of the significant variations reported with regard to these values in the literature. Stoichiometric and off-stoichiometric compositions of Ni3Al alloys (with and without boron addition) were investigated. Dilatometric experiments were performed on all the alloys and the ¿ values were estimated over the temperature range from ambient to 1000°C. Two runs were made on each sample under different initial conditions and differences in ¿ values were noticed. The results were analysed based on our earlier X-ray diffraction results. Additional isothermal dilatometric tests were also carried out and a significant volume change was noticed (0.45% contraction) when the alloy quenched from 1000°C was heated to 600°C and held for a long duration. The calorimetric data were obtaindd over the same range of temperature and enthalpy changes, though less distinct, were noticed at around 360, 660 and 900°C. The variations seen further augment our earlier results on the instability of the L12 structure and the existence of a structural transformatio

A study of the Orion cometary cloud L1616

With its cometary appearance and a reflection nebula near its edge facing some bright Orion stars, the Lynd's cloud L1616 shows ample evidence for being affected by one or more of these massive stars. To estimate its mass and star formation efficiency as well as to determine if it is gravitationally bound, we mapped this cloud in J=1{\rightarrow}0 transitions of ^{12}CO and ^{13}CO. It is found that the distribution of the emission in the line {\it wings} show clear evidence for substantial mass motions. Also, the ``virial'' mass of the cloud is found to be five times the actual cloud mass determined from the ^{13}CO column density map. It is argued that this cloud has abnormally high star formation efficiency and is possibly disintegrating. The morphology and the location of the cloud indicate that it is being affected by the star {\epsilon} Orionis which is also possibly responsible for the cloud's unusual star formation efficiency. Over a range of values of the relevant parameters, the star is found to quantitatively satisfy the requirements of being the cause of the observed characteristics of the cloud

Quantum Phases of Ultracold Bosonic Atoms in a One Dimensional Optical Superlattice

We analyze various quantum phases of ultracold bosonic atoms in a periodic one dimensional optical superlattice. Our studies have been performed using the finite size density matrix renormalization group (FS-DMRG) method in the framework of the Bose-Hubbard model. Calculations have been carried out for a wide range of densities and the energy shifts due to the superlattice potential. At commensurate fillings, we find the Mott insulator and the superfluid phases as well as Mott insulators induced by the superlattice. At a particular incommensurate density, the system is found to be in the superfluid phase coexisting with density oscillations for a certain range of parameters of the system.Comment: 7 pages, 11 figure