Low-density close-closed loop burst error detecting codes

In this paper, we study cyclic codes detecting a subclass of close-closed loop bursts viz. low-density close-closed loop bursts. A sub-class of CT close-closed loop bursts called CT low-density close-closed loop bursts is also studied.     

OB-fold: growing bigger with functional consistency

It was predicted that the folding space for various protein sequences is restricted and a maximum of 1000 protein folds could be expected. Although, there were about 648 folds identified, general functional features of individual folds is not thoroughly studied. We selected OB-fold, which is supposed to be an oligonucleotide and oligosaccharide binding fold to study the general functional features. OB-fold is a small beta-barrel fold formed from 5 strands connected by modulating loops. We observed consistently 2 or 3 loops on the same face of barrel acting as clamps to bind to their ligands. Depending on the ligand, which could be a single or double stranded DNA/RNA or an oligosaccharide, and their conformational properties the loops change in length and sequence to accommodate various ligands. Different classes of OB-folded proteins were analyzed and found that the functional features are retained in spite of negligible sequence homology among various proteins studied.     

Resolution of the non-steady-state kinetics of the elimination of HBr from 2-(p-nitrophenyl)ethyl bromide in alcohol/alkoxide media

Non-steady-state kinetic studies reveal that the elimination of HBr from 2-(p-nitrophenyl)ethyl bromide in alcohol/alkoxide media, the classical concerted E2 reaction, actually takes place by a two-step mechanism involving the intermediate formation of the carbanion.     

Cyanuric chloride: decent dehydrating agent for an exclusive and efficient synthesis of kinetically controlled isomaleimides

Starting from maleanilic and maleamic acids, a facile general approach to kinetically controlled isomaleimides has been described for the first time using cyanuric chloride as a dehydrating agent with 85-98% yields. The effect of a variety of substituents present on the aromatic ring in amine and maleic anhydride moiety, on these kinetic/thermodynamic dehydration processes of anilic acids has been also described. Under the same set of reaction conditions the phthalanilic acid gave kinetically controlled product, isophtalimide in 91% yield, while the corresponding succinanilic acid furnished the thermodynamically more stable succinimide in high yield.     

Resolution of the non-steady-state kinetics of the two-step mechanism for the Diels-Alder reaction between anthracene and tetracyanoethylene in acetonitrile

The Diels-Alder reaction between anthracene and tetracyanoethylene in acetonitrile does not reach a steady-state during the first half-life. The reaction follows the reversible consecutive second-order mechanism accompanied by the formation of a kinetically significant intermediate. The experimental observations consistent with this mechanism include extent of reaction-time profiles which deviate markedly from those expected for the irreversible second-order mechanism and initial pseudo first-order rate constants which differ significantly from those measured at longer times. It is concluded that the reaction intermediate giving rise to these deviations cannot be the charge-transfer (CT) complex, which is formed during the time of mixing, but rather a more intimate complex with a geometry favorable to the formation of the Diels-Alder adduct. The kinetics of the reaction were resolved into the microscopic rate constants for the individual steps. The rate constants, as shown in equation 1, at 293 K were observed to be 5.46 M(-)(1) s(-)(1) (k(f)), 14.8 s(-)(1) (k(b)), and 12.4 s(-)(1) (k(p)). Concentration profiles calculated under all conditions show that intermediate concentrations increase to maximum values early in the reaction and then continually decay during the first half-life. It is concluded that the charge-transfer complex may be an intermediate preceding the formation of the reactant complex, but due to its rapid formation and dissociation it is not detected by the kinetic measurements.     

An Ultra-Microporous Metal–Organic Framework with Exceptional Xe Capacity

Molecular confinement plays a significant effect on trapped gas and solvent molecules. A fundamental understanding of gas adsorption within the porous confinement provides information necessary to design a material with improved selectivity. In this regard, metal–organic framework (MOF) adsorbents are ideal candidate materials to study confinement effects for weakly interacting gas molecules, such as noble gases. Among the noble gases, xenon (Xe) has practical applications in the medical, automotive and aerospace industries. In this Communication, we report an ultra-microporous nickel-isonicotinate MOF with exceptional Xe uptake and selectivity compared to all benchmark MOF and porous organic cage materials. The selectivity arises because of the near perfect fit of the atomic Xe inside the porous confinement. Notably, at low partial pressure, the Ni–MOF interacts very strongly with Xe compared to the closely related Krypton gas (Kr) and more polarizable CO₂. Further ¹²⁹Xe NMR suggests a broad isotropic chemical shift due to the reduced motion as a result of confinement.     

Room temperature thermoelectric performance of Methyl Ammonium Lead Iodide Perovskite and their MWCNT-PANI composites

The excellent properties of Methyl Ammonium Lead Iodide (MAPI) have already created an extensive research interest in photovoltaic applications. However, their utility in thermoelectric application is still not realized thoroughly by researchers. By continuing this interest, we have explored the formation of low dimensional CH₃NH₃PbI₃ (MAPI) perovskite in presence of Polyaniline (PANI) and Multi-Walled Carbon Nanotubes (MWCNT) and its thermoelectric performance. For this purpose, a two stage, in-situ synthesis method was developed to prepare various composites such as MAPI-PANI, MWCNT-MAPI and MWCNT-PANI-MAPI. The as-formed MWCNT-PANI-MAPI composite revealed p-type conductivity with enhanced ZT (up to ~20,000 times) and power factor (3000 times) at room temperature as compared to pristine MAPI sample. Finally, we have demonstrated a proto-type thermoelectric power generator (TE device) fabricated using the best performing composite sample and measured its power output and efficiency at varied δT.