Detection of gravitational waves using a network of detectors

We formulate the data analysis problem for the detection of the Newtonian coalescing-binary signal by a network of laser interferometric gravitational wave detectors that have arbitrary orientations, but are located at the same site. We use the maximum likelihood method for optimizing the detection problem. We show that for networks comprising of up to three detectors, the optimal statistic is just the matched network-filter. Alternatively, it is simply a linear combination of the signal-to-noise ratios of the individual detectors. This statistic, therefore, can be interpreted as the signal-to-noise ratio of the network. The overall sensitivity of the network is shown to increase roughly as the square-root of the number of detectors in the network. We further show that these results continue to hold even for the restricted post-Newtonian filters. Finally, our formalism is general enough to be extended, in a straightforward way, to address the problem of detection of such waves from other sources by some other types of detectors, eg., bars or spheres, or even by networks of spatially well-separated detectors.     

Quality profile of litchi (Litchi chinensis) cultivars from India and effect of radiation processing

Litchi (Litchi chinensis) is a non-climacteric tropical fruit. The fruit has a short shelf-life making its marketing difficult. Physical, biochemical, microbiological, and organoleptic properties of two major commercially grown Indian cultivars of litchi, ‘Shahi’ and ‘China’ were studied. The effect of gamma radiation processing and low temperature storage on the above parameters was evaluated to standardize the optimal process parameters for shelf-life extension of litchi. Physical and biochemical parameters analyzed included weight, moisture, pH, titratable acidity, texture, color, total and reducing sugar, total soluble solids, vitamin C, and flavonoid content. Weight, moisture content, and pH in the fresh fruit ranged between 21–26 g, 74–77%, and 3.7–4.4, respectively, whereas, total and reducing sugar ranged 10–15, and 10–13 g%, respectively. In ‘Shahi’ vitamin C content was found to be around 17–19 mg%, whereas, in ‘China’ it was 22–28 mg%. Flavonoid content was in the range of 26–34 μg catechin equivalents/g of fresh fruit. Total surface and internal bacterial load was around 4 and 3 log cfu/g, respectively. Surface yeast-mold count (YMC) was ～3 log cfu/g whereas internal YMC was ～2 log cfu/g. Radiation treatment reduced microbial load in a dose dependent manner. Treatment at 0.5 kGy did not significantly affect the quality parameters of the fruit. Treated fruits retained the “good” organoleptic rating during storage. Thus, radiation treatment (0.5 kGy) in combination with low temperature (4 °C) storage achieved a shelf-life of 28 days for litchi fruit.     

Biosynthesized Zinc Oxide Nanoparticles as Efficient Photocatalytic and Antimicrobial Agent

This work reports an innovative, effortless and inexpensive method for the preparation of ZnO nanoparticles by green approach using leaf extract of Piper betleas a reducing-stabilizing negotiator. The prepared ZnO NPs were characterized through XRD, FTIR, UV–Visible spectroscopy, and EDX etc. The band gap energy of the sample was estimated as 3.41 eV which is larger than the bulk ZnO (E_g?=?3.37 eV). The observed blue shift is attributed to the quantum confinement of excitons. FTIR analysis showed the presence of alkaloids, flavonoids, polyphenols, and terpenoid. TEM analysis showed that each nanoparticle comprised of 1 to 2 nano-crystallites. Photocatalytic activity results revealed that ZnO-NPs prepared through green synthesis route were found to be efficient in the degradation of toxic reactive red dye with degradation efficiency of 96.4% having high photodegradation rate-constant of 1.6?×?10^–2 min^?1. As an antimicrobial agent, the ZnO NPs are effective against both gram-positive (Bacillus subtilis) and negative bacteria (Escherichia coli), with the zones of clearance as 16.4 and 14.3 mm, respectively. Therefore, present research signifies an effective approach to utilize as-prepared ZnO NPs as efficient photocatalysts as well as antimicrobial agent.

     

Experimental analysis of current conduction through thermally grown SiO<Subscript>2</Subscript> on thick epitaxial 4H-SiC employing Poole-Frenkel mechanism

Electrical properties of SiO₂ grown on the Si-face of the epitaxial 4H-SiC substrate by wet thermal oxidation technique have been experimentally investigated in metal oxide-silicon carbide (MOSiC) structure with varying oxide thicknesses employing Poole-Frenkel (P-F) conduction mechanism. The quality of SiO₂ with increasing thickness in MOSiC structure has been analysed on the basis of variation in multiple oxide traps due to effective P-F conduction range. Validity of Poole-Frenkel conduction is established quantitatively employing electric field and the oxide thickness using forward I–V characteristics across MOSiC structures. From P-F conduction plot (ln(J/E) vs. E ^1/2), it is revealed that Poole-Frenkel conduction retains its validation after a fixed electric field range. The experimental methodology adopted is useful for the characterization of oxide films grown on 4H-SiC substrate.     

Influence of urea additives on micellar morphology/protein conformation

The present study highlights the fact that the effect of additives (urea, monomethylurea, thiourea) on the supramolecular assemblies and proteins is strikingly similar. To investigate the effect, a viscometeric study on sphere-to-rod transition (s-->r) was undertaken in a system (3.5% tetradecyltrimethylammonium bromide+0.05 M NaBr + 1-pentanol [P.M. Lindemuth, G.L. Bertand, J. Phys. Chem. 97 (1993) 7769]) in the presence and absence of the said additives. [1-pentanol] needed for s-->r (i.e. [1-pentanol]s-->r) was determined from the relative viscosity versus [1-pentanol] profiles. It was observed that the additives preponed as well as postponed s-->r depending upon their nature and concentrations. These effects are explained in terms of increased polarity of the medium and the adsorption ability of urea/monomethylurea on the charged surfactant monomers of the micelle. In case of thiourea, postponement of s-->r was observed throughout which is attributed to its structure. To derive an analogy between micelles and proteins the additive-induced conformational changes of the protein, bovine serum albumin (BSA) was taken to monitor secondary structural changes and tryptophanyl fluorescence. A marked increase in secondary structure (far-UVCD) and increased tryptophanyl fluorescence with a marked blue shift in lambdamax was observed in presence of low concentrations of urea or alkylurea. This indicates that a more compact environment is created in presence of these additives, if added judiciously. Addition of thiourea to BSA caused a marked quenching without any significant change in lambdamax. The large decrease in tryptophanyl emission in presence of low thiourea concentrations seems to be specific and related to thiourea structure as no corresponding changes were observed in urea/alkylurea. All these effects pertaining to protein behavior fall in line with that of morphological observations on the present as well as surfactant systems studied earlier [S. Kumar, N. Parveen, Kabir-ud-Din, J. Phys. Chem. B 108 (2004) 9588].     

Insulator-metal phase diagram of the optimally doped manganites from the disordered Holstein-double exchange model

We study the Holstein-double exchange model in three dimensions in the presence of substitutional disorder. Using a new Monte Carlo technique we establish the phase diagram of the clean model and then focus on the effect of varying electron-phonon coupling and disorder at fixed electron density. We demonstrate how extrinsic disorder controls the interplay of lattice polaron effects and spin fluctuations and leads to widely varying regimes in transport. Our results on the disorder dependence of the ferromagnetic T(C) and metal-insulator transitions bear direct comparison to data on the "optimally doped," x = 0.3-0.4, manganites. We highlight disorder induced polaron formation as a key effect in these materials, organize a wide variety of data into a simple "global phase diagram," and make several experimental predictions.     

Rapid synthesis and biological evaluation of 1,4-dihydropyridine derivatives containing a benzothiazolyl moiety

A series of N-(6-methylbenzothiazolyl)-2,3,5,6-tetrasubstituted-4-(aryl)-1,4-dihydropyridines were synthesized by reaction of 2-amino-6-methylbenzothiazole, aromatic aldehyde and active methylene compound in methanol by conventional, as well as, microwave irradiation (solvent free and solid support) methods. The microwave irradiation technique gives better yield and shorter reaction time. Among solid supported microwave irradiation better yields are obtained in acidic alumina as compared to silica, neutral alumina, and basic alumina. All compounds were tested for antibacterial and antifungal activities and results have been compared with standard drugs. Entomological activities were also tested. The results showed that a change in the substitution pattern in 1,4-dihydropyridine derivatives may cause a marked effect on their antimicrobial activity.     

Consequence of doping mediated strain and the activation energy on the structural and optical properties of ZnO:Cr nanoparticles

We report on the sol-gel synthesis of Zn_1−xCr_xO (x=0.0, 0.05, 0.10, 0.15 and 0.20) nanoparticles. These nanoparticles were characterized by using thermogravimetry/differential scanning calorimetry (TG/DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman and Photoluminescence (PL). Electronegativity of Cr ions (Cr³⁺) reduces the final decomposition temperature by 40 °C and activation energy of the reaction when Cr is doped into ZnO. Doping of higher Cr concentration (x≥0.10) into ZnO shows formation of secondary spinel (ZnCr₂O₄) phase along with the hexagonal (ZnO) and is revealed by XRD. Formation of secondary phase changes the activation energy of the reaction and thus the strain in ZnO lattice. In Raman spectra, additional Raman modes have been observed for Zn_1−xCr_xO nanoparticles, which can be assigned to the modes generated due to Cr doping. The Cr doping into ZnO is also supported by PL, in which vacancies are formed with Cr ion incorporation and emission band shifts towards higher wavelength.     

Interface identification by non-local autoionization transitions

We use an autoionization process that involves ultrafast energy transfer to neighbouring sites to characterize the formation of NeAr van der Waals bonds in clusters formed by a coexpansion of both gases. This autoionization process, the so-called interatomic or intermolecular coulombic decay (ICD), is ubiquitous in weakly bonded systems. The energy of the electron being emitted in the ICD process is shown to be characteristic of the two neighbouring entities and is therefore suggested as a new means for structural investigation, such as interface identification, of weakly bonded complexes.