An all optical approach for developing a system involving Kerr material based switches for cryptographic encoding of binary data depending on the input parity

Optics is a highly potential candidate in super fast data computation and communication because of its strong inherent parallelism. Several all optical logic, arithmetic and data processing systems have been proposed in the last few decades. Many all optical digital encoders and decoders are also reported. In this paper we propose a new and alternative concept of using optics for encrypting a binary number to a suitable binary code to achieve a secured optical communication. This binary number can bear the supporting alphabets and numerals in communication of data. In this process an encrypted data is checked by necessary parity bit to ensure a secure communication. The result is verified using proper simulation.     

Sensing of Micellar Microenvironment with Dual Fluorescent Probe, Triazolylpyrene (TNDMBPy)

We report a dual fluorescent triazolylpyrene ( ^TNDMB Py) as an efficient fluorescent light-up probe of various micellar microenvironments. The absorption spectra of ^TNDMB Py in an aqueous solution of varying surfactant concentration, CTAB, SDS and TX-100 showed that as the surfactant concentration was increased the absorbance increased with no shift in wavelength maxima. The increase of absorbance in each surfactant solution with increase in surfactant concentration was due to the enhanced solubilization of ^TNDMB Py in surfactant solutions. Our investigations based on steady state and time resolved fluorescence techniques showed that the probe reports the microenvironment of ionic surfactant solutions (CTAB and SDS) via dual emission (LE and ICT) at low surfactant concentration. The ICT band showed a blue shifting pattern with enhanced intensity that disappeared as the concentration of surfactant increases (> 1 mM for CTAB and > 3 mM for SDS). In non-ionic surfactant (Triton X-100) solution, the fluorophore showed dual emission with dominant ICT behaviour over LE emission at low concentration (up to 0.35 mM). In reverse micelle we observed a blue shifted ICT band with no LE band with increasing molar concentration of water. We found 100 nm blue shifting when we moved from R?=?0 to R?=?7, where R is the molar ratio of water to TX-100 (R?=?[H2O]/[TX-100]). The blue shifting of ICT band is because of the movement of the probe from hydrophilic core to hydrophobic core (surface) of the reverse micelle. Thus from the steady-state fluorescence study it was observed that the ICT band of the probe, ^TNDMB Py was more influenced by the micellar environment in comparison to the LE band. This difference in behaviour of the fluorophore is probably because of varying extent of hydrophobic/hydrogen bonding interactions experienced by the probe and its relative disposition inside the various micellar nanocores.      

Korteweg-de Vries hierarchy using the method of base equations

A base-equation method is implemented to realize the hereditary algebra of the Korteweg-de Vries (KdV) hierarchy and the N-soliton manifold is reconstructed. The novelty of our approach is that, it can in a rather natural way, predict other nonlinear evolution equations which admit local conservation laws. Significantly enough, base functions themselves are found to provide a basis to regard the KdV-like equations as higher order degenerate bi-Lagrangian systems.     

Synthesis of furan-fused 1,4-dihydrocarbazoles via an unusual Garratt-Braverman Cyclization of indolyl propargyl ethers and their antifungal activity

The reactivity of indole based bis-propargyl ethers 4a-4g under Garratt-Braverman condition (KOBu^t in refluxing toluene) has been studied. Interestingly, these propargyl systems with one arm attached with substituted 3-indolyl derivatives leaving the other arm unsubstituted produced the 3,4-furan fused dihydrocarbazole derivatives 6a-6g (and not the expected carbazole derivatives) as the predominant product (70–82%) making this methodology to access such derivatives an attractive route. The results are supported by computational studies and some of the carbazole derivatives showed good antifungal activities.     

Theoretical analysis of tautomerization of succinimide and analogous compounds: insights from DFT approach

Tautomerizations of biologically and medicinally important heterocyclic compound, 2,5-pyrrolidinedione, commonly known as succinimide and two of its analogous compounds, 2,4-pyrrolidinedione and 3,4-pyrrolidinedione have been investigated at the density functional theory (DFT)/M06-2X level in aqueous medium, implementing polarizable continuum model (PCM). We have extended our investigation of tautomerism to the sulfur analogues of the aforementioned compounds also, i.e., 2,5-pyrrolidinedithione, 2,4-pyrrolidinedithione, and 3,4-pyrrolidinedithione. Tautomerism observed in these compounds are mainly keto-enol, thio-thiol and amine-imine, but we have detected two new kind of tautomerization shown by some of the abovementioned compounds, named as keto-epoxy (for the oxygen analogue) and thio-thioepoxy (for the sulfur analogue) which have not yet been reported in the literature. Relative energies (E_r) and activation energies (E_a) have been calculated for all the tautomers and tautomerization processes. The potential energy surfaces (PESs) have been constructed using the M06-2X energy values. It has been observed that the energy difference found in the tautomers of sulfur analogues is relatively lower than that of the corresponding oxygen analogues, so does the activation energy barrier. As one-electron redox properties play an important role in biological systems, we have also explored the effect of conformational changes on the overall redox properties of the said compounds by calculating the adiabatic and vertical ionization potentials (AIPs and VIPs, respectively) and adiabatic electron affinities (AEAs).     

Microwave promoted rapid nitration of phenolic compounds with calcium nitrate

Highly accelerated and safe nitration of phenolic compounds has been found to be feasible with a mixture of calcium nitrate and acetic acid as an efficient nitration agent under brief microwave irradiation. This method is compatible with the green chemistry approach because calcium salts—the inorganic byproducts—can be useful agrochemicals rather than waste chemicals. Commercially available ¹⁵N-labeled calcium nitrate is convenient for the preparation of ¹⁵N-labeled compounds for metabolic studies and mass spectrometry. This safe nitration method can be included in laboratory experiments for high school and college students.     

Rapid cyclopeptide analysis by microwave enhanced Akabori reaction

The application of microwave assisted modification of the Akabori hydrazinolysis reaction has been found to cleave cyclic oligopeptides in a selective fashion to produce mainly the hydrazide of a specific linear peptide. This ring cleavage requires a few minutes of reaction in a domestic microwave oven. The linear peptide hydrazide can be analyzed by ESI-MS/MS, FAB-MS, and FAB-MS/MS methods for the determination of the amino acid sequence.     

Reactivity Differences between Carbon Nano Onions (CNOs) Prepared by Different Methods

The carbon nanoparticles obtained from either arcing of graphite under water or thermal annealing of nanodiamonds are commonly called carbon nano onions (CNOs), or spherical graphite, as they are made of concentric fullerene cages separated by the same distance as the shells of graphite. A more careful analysis reveals some dramatic differences between the particles obtained by these two synthetic methods. Physicochemical methods indicate that the CNOs obtained from nanodiamonds (N‐CNOs) are smaller and contain more defects than the CNOs obtained from arcing (A‐CNOs). These properties explain the enhanced reactivity of the N‐CNOs in cycloaddition and oxidation reactions, as well as in reactions involving radicals. Given the easier functionalization of the N‐CNOs, they are the most obvious choice for studying the potential applications of these multi‐shelled fullerenes.     

Synergistic Substrate and Oxygen Activation in Salicylate Dioxygenase Revealed by QM/MM Simulations

Salicylate 1,2‐dioxygenase (SDO) is the first enzyme to be discovered to catalyze the oxidative cleavage of a monohydroxylated aromatic compound, namely salicylate, instead of the well‐known electron‐rich substrates. We have investigated the mechanism of dioxygen activation in SDO by QM/MM calculations. Our study reveals that the non‐heme Fe^II center in SDO activates salicylate and O₂ synergistically through a strong covalent interaction to facilitate the reductive cleavage of O₂. A covalent salicylate–Fe^II–O₂ complex is the reactive oxygen species in this case, and its electronic structure is best described as being between the two limiting cases, Fe^II?O₂ and Fe^II?O₂^.?, with partial electron transfer from the activated salicylate to O₂ via the Fe center. Thus SDO employs a synergistic strategy of substrate and oxygen activation to carry out the catalytic reaction, which is unprecedented in the family of iron dioxygenases. Moreover, O₂ activation in SDO happens without the assistance of a proton source. Our study essentially shows a new mechanistic possibility for O₂ activation.