Photochemical and Photophysical Studies within Zeolites

In this article, we illustrate how one can utilize a zeolite matrix to control the photophysical and photochemical behavior of guest molecules included in them. In the first part, the emphasis is placed on the cation and on a single zeolite, faujasite (X and Y). Photophysical properties of naphthalene and other aromatic guest molecules included in X-type faujasite zeolites (M+X, M = Li, Na, K, Rb, Cs, Tl) have been investigated. As expected for an external heavy-atom-perturbed excited state, both singlet- and triplet-excited-state lifetimes and emission efficiencies depend upon the identity and accessibility of the cation present within the zeolite supercage. The power of the heavy-atom-cation effect in zeolites has been demonstrated by recording phosphorescence from several olefins whose phosphorescence has not previously been recorded. The second section brings out an inherent feature of a field at its infancy-serendipity. Surprisingly, radical ions of organic molecules can be generated and stabilized within zeolites by a simple procedure. This study has been expanded to include oligomers of thiophenes and α,ω-diphenylpolyenes which serve as models for conducting polymers. This is followed by a presentation wherein the importance of the relative size of the host cavity to that of the guest to achieve maximum selectivity in a photoreaction is highlighted. Concepts developed in this section with faujasite and pentasil (ZSM-5 and ZSM-11) as models are believed to be general and applicable to other organized media

Relaxation of Collective Excitations in LJ-13 Cluster

We have performed classical molecular dynamics simulation of $Ar_{13}$ cluster to study the behavior of collective excitations. In the solid ``phase'' of the cluster, the collective oscillation of the monopole mode can be well fitted to a damped harmonic oscillator. The parameters of the equivalent damped harmonic oscillator-- the damping coefficient, spring constant, time period of oscillation and the mass of the oscillator -- all show a sharp change in behavior at a kinetic temperature of about $7.0^oK$. This marks yet another characteristic temperature of the system, a temperature $T_s$ below which collective excitations are very stable, and at higher temperatures the single particle excitations cause the damping of the collective oscillations. We argue that so long as the cluster remains confined within the global potential energy minimum the collective excitations do not decay; and once the cluster comes out of this well, the local potential energy minima pockets act as single particle excitation channels in destroying the collective motion. The effect is manifest in almost all the physical observables of the cluster.Comment: Revised and enlarged. 6 pages RevTeX style. 7 eps figures available on request. To appear in J Chem Phy

Performance of Some Tunnels in Squeezing Rocks of Himalayas

Data regarding the performance of three tunnelling projects in the Himalayan region has been collected. It is seen that rock loads or deformations calculated on the basis of Barton, Bieniawski or RMR approach do not match the field data. A mathematical model has been developed incorporating modifications in the approach of Brown et.al of rock-support interaction, using elastic-strain softening-plastic ground characteristics. A non-linear relationship between radial and tangential strains around the tunnel has been considered and the method of calculation of stresses and deformations altered to incorporate exact integration of the governing differential equation for a thin cylindrical annulus replacing finite difference approximation. It is seen that a closer match and a more rational explanation of the observed data from the tunnelling project is provided by the mathematical model

Association Between Smoking and Oral Lichen Planus in Males - A Retrospective study

Oral lichen planus affects one to two percent of the general adult population and is the most common non‐infectious oral mucosal disease. Tobacco smoking increases the risk of OLP malignant transformation as cigarette smoke contains substances that induce chronic inflammation at mucosal surfaces. The aim of this study was to assess the association between smoking and oral lichen planus in males. A retrospective study was conducted using the case records of patients visiting a private dental college in Chennai from June 2019 - March 2020. The study population included case records of male patients with oral lichen planus, selected by non-probability purposive sampling. Data regarding their smoking habit were collected. Descriptive and inferential statistics were done using SPSS software. Among the study population, 43.59% of patients were below 40 years and 56.41% were above 40 years of age. About 53.8% of male patients with oral lichen planus had a smoking habit. Erosive lichen planus was the most common variant followed by the reticular type.Within the limits of the study, there was a significant association between smoking and oral lichen planus in males, with an increased incidence of erosive lichen planus among smokers

Micellar control of photochemical reactions

Micelles as media for chemical reactions exhibit features that are unique in comparison to ordinary non-aqueous or aqueous solvent media. A thermal or photochemical reaction conducted in micellar media is influenced by the micellar environmental effects resulting in control and/or modification of reactivity. The salient features of micelles and their influence on photochemical reactivity are briefly discussed in this paper

Comfort Level Refinement of Military Tracked Vehicle Crew through Optimal Control Study

Military tracked vehicle and crew are modelled together in this paper as integrated man-machine lumped parameter model, by integrating the simplified 5 degrees of freedom (DoF) tracked vehicle model, including seat and 4 DoF human bio-dynamic model, thus resulting in a 9 DoF simplified vehicle-occupant model. Then the natural frequency of major mass segment namely the chassis mass is obtained through simulation study, for a known road input. The value obtained is compared with that of an earlier research work, for validation of said man-machine model. Then focusing our study locally at crew seat location, parameters of crew seat suspension for ride comfort are optimised using the optimal digital state space controller designed for this purpose by implementing it in a 2 DoF occupant - seat suspension model and its Simulink model constructed. Simulation results illustrate the attainment of the goal by meeting the controller design requirements

Ergonomic Level Improving of Armoured Fighting Vehicle Crew

The armoured fighting vehicle (AFV)-occupant composite system is modelled as a lumped parameter system, in this paper, wherein the 4 degrees of freedom (dof) biodynamic occupant model is integrated with 10 dof in-plane AFV model including the crew seat, thus leading to the 14 dof vehicle-occupant composite model and the governing equations of motion are obtained. The composite model is subjected to idealised road input simulating the ground reaction forces. Natural frequencies and the frequency domain vibration responses of various masses of model are obtained. The natural frequency of chassis thus obtained is compared with the result established by an earlier research work, to validate the model. The study is focused on crew seat location. A 2 dof occupant-seat suspension model is formulated and validated through case study. The optimised values of seat suspension parameters for ride comfort are obtained using the said model, through two methods of Invariant points theory and genetic algorithm toolbox of Matlab 2014a software. Acceleration responses of body for the current and optimised parameter values obtained illustrate that comfort of crew is improved with optimised values through minimization in the acceleration responses

A novel scheduling algorithm to maximize the D2D spatial reuse in LTE networks

In order to offload base station (BS) traffic and to enhance efficiency of spectrum, operators can activate many Device-to-Device (D2D) pairs or links in LTE networks. This increases the overall spectral efficiency because the same Resource Blocks (RBs) are used across cellular UEs (CUEs) (i.e., all UEs connected to BS for both C-Plane and D-plane communication) and D2D links (i.e., where the UEs are connected to BS only for C-plane communication). However, significant interference problems can be caused by D2D communications as the same RBs are being shared. In our work, we address this problem by proposing a novel scheduling algorithm, Efficient Scheduling and Power control Algorithm for D2Ds (ESPAD), which reuses the same RBs and tries to maximize the overall network throughput without affecting the CUEs throughput. ESPAD algorithm also ensures that Signal to Noise plus Interference Ratio (SINR) for each of the D2D links is maintained above a certain predefined threshold. The aforementioned properties of ESPAD algorithm makes sure that the CUEs do not experience very high interference from the D2Ds. It is observed that even when the SINRdrop (i.e., maximum permissible drop in SINR of CUEs) is as high as 10 dB, there is no drastic decrease in CUEs throughput (only 3.78%). We also compare our algorithm against other algorithms and show that D2D throughput improves drastically without undermining CUEs throughput