Information reduction using lensless Fourier transform digital composite holography

An optical hologram contains substantially more information than necessary for some specific applications. Practical methodology of handling huge information contents in these holograms for such applications is cumbersome. In this paper, a method of information reduction, which aims at efficient storage and transmission of holograms, is investigated using digital composite holography in lensless Fourier transform configuration. The maximum information reduction factor obtained in our experiment is 105. The advantages/disadvantages of this method over an earlier method used in optical holography [Lin LH. A method of hologram information reduction by spatial frequency sampling. Appl Opt 1968;7:545] are also discussed.     

Further Meyer–Neldel rule in thermally activated crystallization of chalcogenide glasses

This paper reports the observation of the Further Meyer–Neldel rule in thermally activated crystallization in Se_80?xTe₂₀M_x (M = Ag, Cd, In and Sb); 0 ? x ? 15 chalcogenide glasses. We have investigated Further Meyer–Neldel rule by two different approaches. In the first case, the different sets of Meyer–Neldel pre-factor K₀₀ and Meyer–Neldel energy E_MN are obtained by changing the composition (i.e., value of x) of a particular glassy system keeping the third element (i.e., value of M) constant. In the second case, the different sets of Meyer–Neldel pre-factor K₀₀ and Meyer–Neldel rule energy E_MN are obtained by changing the third element in a particular glassy system keeping the composition constant. The results are explained using the conception of thermal phonons in thermally activated crystallization analogous to optical phonons in thermally activated electric conduction.     

Optical characterization of tin containing novel chalcogen rich glassy semiconductors

Amorphous thin film materials with different compositions of Se_80?xTe₂₀Sn_x (0 ≤ x ≤ 10) system have been deposited on glass substrates by a well known thermal evaporation technique. Structural characterization of different compositions of aforementioned system has been done by Raman spectroscopy. The optical properties of thin films have been studied in the wavelength range 200–1100 nm by the utilization of the optical absorbance spectra of deposited thin films. To calculate the optical band gap from the optical absorption spectra, we have used Tauc model that follows the mechanism of allowed ‘non-direct electronic transition’. Subsequently, we have determined the energy band gap, metallization criterion and refractive index of thin films of aforesaid system. The variation in optical properties with composition has been interpreted in terms of density of defect states.     

N-methyl Benzimidazole Tethered Cholic Acid Amphiphiles Can Eradicate S. aureus-Mediated Biofilms and Wound Infections

Infections associated with Gram-positive bacteria like S. aureus pose a major threat as these bacteria can develop resistance and thereby limit the applications of antibiotics. Therefore, there is a need for new antibacterials to mitigate these infections. Bacterial membranes present an attractive therapeutic target as these membranes are anionic in nature and have a low chance of developing modifications in their physicochemical features. Antimicrobial peptides (AMPs) can disrupt the microbial membranes via electrostatic interactions, but the poor stability of AMPs halts their clinical translation. Here, we present the synthesis of eight N-methyl benzimidazole substituted cholic acid amphiphiles as antibacterial agents. We screened these novel heterocyclic cholic acid amphiphiles against different pathogens. Among the series, CABI-6 outperformed the other amphiphiles in terms of bactericidal activity against S. aureus. The membrane disruptive property of CABI-6 using a fluorescence-based assay has also been investigated, and it was inferred that CABI-6 can enhance the production of reactive oxygen species. We further demonstrated that CABI-6 can clear the pre-formed biofilms and can mitigate wound infection in murine models.     

Catalytic trimerization of isocyanates by neutral pentacoordinated silicon hydrides

Pentacoordinated hydrosilanes react with excess of aryl isocyanates to give isocyanurates under mild and neutral conditions. The catalytic species are the initially formed N-silylformamides, which incorporate three equivalents of isocyanate, and then rearrange to N-silylformamide and isocyanurates.     

Gross Dissolution of Natural Rhombohedral-shaped Calcite in Glacial Acetic Acid

Gross dissolution of natural rhombohedral-shaped calcite crystals in different concentrations of glacial acetic (0.3 to 3.4 M) diluted by distilled water is studied. Activation energy of reaction between calcite crystal and acetic acid is calculated and found constant. The preexponential factor is not constant with different concentrations. Weight loss per unit surface area versus concentration of acetic acid is plotted at various temperatures (30 to 55 °C). It is found that the maximum weight loss per unit surface area occurs with 2.5 M of glacial acetic acid for the above temperature range. The value of the pre-exponential factor is also maximum at 2.5 M of acetic acid. The maximum weight loss per unit surface area is explained with the help of ionic conductivity and viscosity of the etchant.     

Excitation of Forbidden Electronic Transitions in Atoms by Hermite–Gaussian Modes

Photoexcitation of trapped ions by Hermite–Gaussian (HG) modes from guided beam structures is proposed and investigated theoretically. In particular, simple analytical expressions for the matrix elements of induced atomic transitions are derived that depend both on the parameters of HG beams and on the geometry of an experiment. By using these general expressions, the ${}^2{S}_{1/2}\to {}^2{F}_{7/2}$ electric octupole (E3) transition is investigated in an Yb⁺ ion, localized in the low–intensity center of the HG₁₀ and HG₀₁ beams. It is shown how the corresponding Rabi frequency can be enhanced by properly choosing the polarization of incident light and the orientation of an external magnetic field, which defines the quantization axis of a target ion. The calculations, performed for experimentally feasible beam parameters, indicate that the achieved Rabi frequencies can be comparable or even higher than those observed for the conventional Laguerre–Gaussian (LG) modes. Since HG-like modes can be relatively straightforwardly generated with high purity and stability from integrated photonics, these results suggest that they may form a novel tool for investigating highly-forbidden atomic transitions.     

Etch Pit Morphology on Calcite Cleavages by Glacial Acetic Acid

Etch pit morphology has been studied on calcite cleavages by different concentration of glacial acetic acid. Lateral reaction rates are very less at high concentration as well as low concentration of glacial acetic Acid. Etch pit morphology changes due to formation of finite or infinite lateral reaction rates at some particular concentration called transition concentration. The underlying chemical equations are given for different etch pit morphology.