Oxidation of tryptophan (Trp) by potassium permanganate in acid, neutral and alkaline media led to the formation of the corresponding aldehyde (indole-3-acetaldehyde), ammonia and carbon dioxide. The oxidation kinetics was studied by a spectrophotometric technique at fixed ionic strengths and at 25 o C. All the reactions showed a first order dependence on [MnO4 - ] and fractional-first order kinetics in [Trp]. Fractional-second order kinetics in [H+ ] and fractional-first order dependence with respect to [OH- ] were revealed in acid and alkaline media, respectively. An increase in the ionic strength in alkaline medium increased the oxidation rate of tryptophan, whereas it had a negligible effect on the oxidation rate in acid medium. Plausible oxidation mechanisms in all media were suggested and the rate-laws expressions were derived. Furthermore, the reactions constants included in the various steps of the suggested mechanisms were evaluated.

The kinetics of platinum(IV) oxidation of cadaverine (CAD) in perchloric acid medium was studied at a constant ionic strength of 2.0 mol dm-3 and at 25°C. The oxidation reaction was followed spectrophotometrically. The reaction exhibited a first order kinetics in [PtIV] and less than unit order dependences with respect to [CAD] and [H+ ]. Increasing ionic strength and dielectric constant decreased the oxidation rate. The final oxidation products of cadaverine were identified as 5-aminopentanal and ammonia. The oxidation mechanism was proposed and the appropriate rate-law expression was deduced. The activation parameters of the second order rate constant were evaluated and discussed.

Sodium N-dodecyl arginine surfactant (sodium 2-(dodecylamino)-5-guanidinopentanoate) was synthesized and examined as an inhibitor for the corrosion of Sabic iron in acidic (HCl), neutral (NaCl) and alkaline (NaOH) media using different techniques, namely, weight-loss (WL), potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS). Increasing the concentrations of the acidic, neutral and alkaline media increased the corrosion rates of Sabic iron and increased the corrosion rate in the order: HCl >> NaCl > NaOH. It was found that the inhibition efficiency of the inhibitor increased with the concentration of the inhibitor while decrease with raising temperature. The results indicate that the inhibition efficiency of the inhibitor increased in the studied media in the sequence: HCl > NaCl > NaOH. The high inhibition efficiency of arginine surfactant inhibitor was interpreted on the basis of strong adsorption of the inhibitor molecules on the surface of Sabic iron and forming a protective film. The adsorption was found to obey Langmuir adsorption isotherm. The evaluated thermodynamic and kinetic parameters support the mechanism of physical adsorption of the inhibitor. The results obtained from all used techniques are in a good agreement with each others.

This paper describes a novel method for the removal of potassium tellurite (TeIV), a toxic tellurium (IV) compound, via its bioreduction using the drug flucloxacillin (Flx) in an aqueous sulfuric acid solution. The kinetics of the bioreduction process were monitored using UV–Vis absorption spectra at an ionic strength of 2.0 mol dm−3 and 298 K. The reaction between TeIV and Flx was set at a 1:1 stoichiometry. The reduction reaction followed first-order kinetics for [Flx] and fractional-first-order kinetics for [TeIV] and [H+]. The effects of ionic strength and relative permittivity of the reaction medium were also explored. Supplementation with divalent transition metal ions enhanced the reduction rate. The reaction products were identified, in order of their stoichiometric results, spot tests and FT-IR spectra as 3-(2-chloro-6-fluorophenyl)-5-methylisoxazol-4-carbocylic acid, 5,5-dimethyl-thiazolidine-2,4-dicarboxlic acid, ammonium ion, carbon dioxide and elemental tellurium (Te0 ). The reaction rate dependence on temperature was studied, and the activation and thermodynamic parameters were assessed and discussed. The derived rate-law expression was found to be in excellent accordance with the acquired investigational outcomes. A conceivable reaction mechanism has been provided, which includes a reaction between the protonated flucloxacillin (Flx+) and tellurous acid (H2TeO3) as the essential reactive species, resulting in the construction of an intermediate complex. Such complex decays in the rate-determining step to yield the final reaction products.

We report the photolumenses (PL) and dielectric measurements of Cd(1-x)CoxO nanocomposites with (0.00 ≤ x ≤ 1.00). It is found that an increase in x correlates with a significant change in crystallite size, particle size, porosity, Debye temperature, Young’s modulus, q-factor, binding energy, impedance of grains and their boundaries. The samples with x = 0.50 or 0.60 show an adverse change in the behavior of these parameters. We could not evaluate any shift in the wave length of PL emissions, although they are different in intensities. The samples of x = 0.40 and 1.00 show more visible emission colors at 640, 678, 716, and 791 nm. The x = 0.00 sample shows a negative dielectric constant (ε\ ), but it crossovers to positive for the other values of x. ε\ was gradually decreased as frequency increased up to 10 KHz, after which it nearly saturated except x = 0.80, in which it linearly decreased and never saturated. The ac conductivity decreased gradually against x such that the type of conduction is dependent on the chosen x. The Cole-Cole plot shows a straight line for x = 0.00 and arcs for x = 0.20 and 0.60, and a complete semicircular for x = 0.40, 0.50, 0.80 and 1.00. Furthermore, the effective capacitance was 9260 μF for x = 0.00, but it drops to 0.013 μF for x = 0.40, whereas the vice is true for bulk resistance. These results lend a reasonable certainty to the assertion that Co substitutes for Cd and make them potential prospects for devices such as diodes that emit light, cathode-luminescence displays, integrated circuits, Li-battery and supercapacitors

Iron has many advantages, which makes it a material of great importance on the industrial level, but it is quickly affected by surrounding environmental factors that cause its corrosion. In this context, two new Schiff base cyclohexanamine derivatives (CSBs) were synthesized, characterized, and screened as corrosion inhibitors of Csteel in a 1 M hydrochloric acid solution. Specifically, they are (Z)-N-cyclohexyl-1-phenylethan-1-imine (CSB-1) and (E)-N′-cyclohexyl-N-hydroxybenzimidamide (CSB-2). 1 H NMR was used to determine the structures of the new CSB molecules. The inhibition efficacies (%IE) were evaluated by combining theoretical, physical, chemical, electrochemical, and spectroscopic methods. The results confirmed that CSBs were mixed-type inhibitors and that the IE depended linearly on their concentration. The adsorption of these molecules on the metal surface is key to this role. Kinetic and thermodynamic studies indicated that they are physically adsorbed and subject the Langmuir adsorption isotherm. Using 0.001 M of inhibitor, the maximum %IEs achieved were 91.1 % for CSB-1 and 94.4 % for CSB-2, respectively, which confirms tatehat they are promising inhibitors. Surface analysis via atomic force microscopy (AFM) confirmed that the C-steel was covered in a protective layer. Several thermodynamic and kinetic parameters were calculated. DFT and Mullikan charge calculations and molecular dynamics (MD) simulations were applied to predict the effectiveness and interactions of new CSBs on the steel surface as well. Theoretical expectations correspond to the practical.

We present a groundbreaking and versatile approach to multi-mode rainbow trapping in photonic crystal waveguides (PCWs), overcoming long-standing limitations in photonic device design. Our innovative semi-bilayer PC design, formed by stacking two PCs, enables the realization of new photonic modes that were previously inaccessible, leading to enhanced device flexibility, improved performance, and increased resilience to defects and imperfections. By meticulously engineering a chirped PC within the PCW, we achieve multi-mode light trapping at distinct positions for different frequencies along the waveguide, effectively creating a rainbow of light. This study paves the way for efficient and robust trapping and demultiplexing of multiple wavelengths, opening up new avenues for on-chip nanophotonic applications. Moreover, the realization of ultra-high-quality (Q) factor Fano resonances within the waveguide cavity unveils unprecedented possibilities for designing on-chip nanophotonic devices. The diverse array of Fano resonances holds immense potentials for developing novel optical filters, switches, and lasers with exceptionally low thresholds. Our proposed structure offers a more compact, efficient, and robust solution for multi-wavelength photonic device applications.

Chemical structural engineering is a helpful method to design the semi-conductors for organic solar cells (OSCs).
The understanding of structural and electronic properties of materials is essential for designing and calibration of
materials. By making structural adjustments at the terminal position, new small molecule acceptors can be
created. Electronic properties are studied in detail. Electrostatic potential both in qualitative and quantitative
way is studied to explore the electron density distribution. The electron density is signifcantly changed on the
change of terminal groups. The excited state behaviour has also undergone a noticeable alteration. The increase
in electron-defcient character at the terminal location causes the absorption spectra to shift to the red. The
structural changes have an important effect on non-covalent interactions also. Through molecular dynamics
(MD) simulations, the bulk behaviour of pure small molecule acceptors and their blend with polymer donor PM6
is examined. Radial distribution function is attained from MD simulations. The alteration in terminal groups has
signifcantly changed the packing behavior of pristine acceptors and their blend with polymer donor.
 

Topological photonics and topological photonic states have opened up a new frontier
for optical manipulation and robust light trapping. The topological rainbow can separate different
frequencies of topological states into different positions. This work combines a topological
photonic crystal waveguide (topological PCW) with the optical cavity. The dipole and quadrupole
topological rainbows are realized through increasing cavity size along the coupling interface. The
flatted band can be obtained by increasing cavity length due to interaction strength between the
optical feld and defected region material which is extensively promoted. The light propagation
through the coupling interface is built on the evanescent overlapping mode tails of the localized
felds between bordering cavities. Thus, the ultra-low group velocity is realized at a cavity
length more than the lattice constant, which is appropriate for realizing an accurate and precise
topological rainbow. Hence, this is a novel release for strong localization with robust transmission
and owns the possibility to realize high-performance optical storage devices.