Papers

Active and passive noise controlling methods are widely used for noise reduction applications as it is essential to control unwanted noise and vibration which adversely affects human life, wild life, aquatic life and the ecosystem as such. The technological, automobile and biomedical world also prefer noise and vibration free atmosphere for the efficient performance. However, passive noise reduction at lower frequency range is highly challenging due to the unavailability of suitable materials. The emergence of engineered composite materials pave way to this bottle neck problem. Herein, natural fiber composites are synthesized using Vacuum Assisted Resin Transfer Molding and characterized for noise reduction in the low frequency region with the help of transfer matrix method using an impedance tube. The results show that the natural micro fibrous basalt fiber composite is a highly efficient sound absorber in the lower frequency region compared to the glass fiber based one. The fiber radius is critical in tuning the frequency range. The contact angle measurements reveals that the basalt fiber composite is more hydrophobic in nature.

In the present work, different methods were used to calculate the atomic cross-sections, electronic cross-sections, effective Z, effective electron density and mean free path for the Bi4Ge3O12 gamma ray detector popularly known as BGO detector. The methods are Direct method using attenuation coefficients evaluated using WinXCom software, the others are DirectZeff software, AutoZeff software, XMuDat software and still another method used is Power law method. The results of first two methods i. e. Direct method and Direct Zeff software are in good agreement with each other. These results are also reproduced nicely by power law method. The Zeff predicted by AutoZeff are too large compared with our predictions and XMuDat predicts too small value for Zeff

The alpha–hydroxy acids (AHA) are naturally occurring organic acid. The oxidation of mandelic acid by pyridiniumdichromate has been studied spectrophotometrically in presence of p-toluenesulphonic acid (PTSA) in dimethylsulphoxide (DMSO) as a solvent. The rate of reaction decrease & with an increase in polarity of solvent indicating an ion-dipole interaction in the slow step. The reaction exhibit no primary kinetic isotope effect. The activation parameters have been evaluated.