Narrow Results

We examine different generalizations of checking stack automata by allowing multiple input heads and multiple stacks, and characterize their computing power in terms of two-way multi-head finite automata and space-bounded Turing machines. For various models, we obtain hierarchies in terms of their computing power. Our characterizations and hierarchies expand or tighten some previously known results. We also discuss some decidability questions and the space/time complexity of the models.

The growth of ternary semiconductor thin films of cadmium indium selenide nanofibers has been carried out from aqueous solution of cadmium sulphate, indium trichloride, and selenium dioxide by electrochemical route. These thin films have been further optimized using photoelectrochemical cell (PEC). Optimized thin film has been characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).

Porous silicon (PS) samples were prepared by electrochemical anodic etching of n-type (111) silicon wafers in HF solution. The structural, optical, and chemical features of the PS were investigated in terms of different etching durations. The porous samples were investigated by scanning electron microscopy (SEM), photoluminescence (PL), and Raman scattering. SEM images indicated that the pores increased with the etching duration; however, the etching duration has significant effect on the shape of the pores. PL measurements revealed that the porosity-induced PL intensity enhancement was only observed in the porous samples. Raman spectra showed shifting of PS Raman peak to lower frequency relative to non-porous silicon Raman peak.

Si-doped diamond films with various Si concentrations are deposited on WC-Co substrates using HFCVD method, with the mixture of acetone, tetraethoxysilane (TEOS) and hydrogen as the reactant source. A variety of characterizations, including FE-SEM, AFM, Raman, XRD, surface profilometer and Rockwell indentation, are conducted to systematically investigate the influence of Si incorporation on diamond films. As the Si/C ratio from 0% to 5%, the grain size of as-deposited films decreases from 4 μm to about 50 nm, and the surface roughness reduces from Ra ~ 290 nm to Ra ~ 180 nm. Besides, the intensity ratio of I(111)/I(220) varies from 0.57 to 0, indicating the 〈110〉 preferred orientation of the nanocrystalline structure in the 5% doped diamond films. The silicon doping is beneficial for the formation of non-diamond carbide phases in the films, according to the Raman spectra. Moreover, the film adhesion is also improved with the increase of Si/C ratio.

The copper quantum dots (Cu QDs) are successfully green synthesized from copper sulfate (CuSO${}_4)$ as precursor material using plant leaf extracts of Mangifera indica. The mangiferin as a natural glucosylxanthone present in leaf extract of M. indica acquires antioxidant, antimicrobial, antidiabetic, antiallergic, anticancer, hypocholesterolemic, and immunomodulatory activity, which acts as an effective stabilizing and reducing agent for conversion of the copper ion (Cu${}^{2+})$ into the Cu QDs in aqueous medium. The green synthesized Cu QDs are characterized using ultraviolet–visible (UV–Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, fluorescence spectroscopy, dynamic light scattering instrumental techniques, which confirm the successful synthesis and photoluminescence (PL) behavior of the Cu QDs. The ultrasonic investigation was carried out to find out the variation of ultrasonic velocity and density with concentration of Cu QDs in aqueous leaf extracts of M. indica plant as well as to calculate the dependency of acoustical parameter, namely adiabatic compressibility, acoustic impedance, and intermolecular free length on concentrations. The synthesized Cu QDs are biocompatible that can be a potential candidate for various in vivo and in vitro applications such as antioxidant, antimicrobial, anticancer, biosensor, bioimaging, and biocatalysis fields.

A Boolean graph is the zero divisor graph of a Boolean ring. For a positive integer n, let [n] = {1, 2,…,n}, and 2^[n] the power set of [n]. A finite Boolean graph B_n is isomorphic to a graph defined on the vertex set $2^{\left[n\right]}\backslash \left\{\left[n\right],\cancel{0}\right\}$, where two vertices are adjacent if and only if their meet is empty. In this paper, we give a survey of some works done in the area of research related to Boolean graphs, in both graph theoretic and algebraic aspects. We also introduce some most recent works by the author and others.