Noise induced transition in Josephson junction with second harmonic

We show a noise induced transition in Josephson junction with fundamental as well as second harmonic. A periodically modulated multiplicative colored noise can stabilize an unstable configuration in such a system. The stabilization of the unstable configuration has been captured in the effective potential of the system obtained by integrating out the high frequency components of the noise. This is a classical approach to understand the stability of an unstable configuration due to the presence of such stochasticity in the system and our numerical analysis confirms the prediction from the analytical calculation.     

Green Oxidation of Methylarenes to Benzoic Acids with Bromide/Bromate in Water

An efficient and convenient procedure has been developed for the oxidation of methylarenes to the corresponding benzoic acids using a bromide/bromate-based reagent system in water. Regeneration and reusability of the bromide/bromate reagent is demonstrated.     

Copper(II) Bromide–Catalyzed C-C/C-N Bond-Forming Reactions: Synthesis of Pyrrole-Incorporated Triarylmethanes

We have achieved a facile copper(II) bromide–catalyzed synthesis of 2,3,4-trisubtitued pyrrole incorporated into unsymmetrical triarylmethanes through direct replacement of hydroxyl group in the pyrrolyl phenyl methanol with electron-rich aromatic and heteroaromatic compounds. The newly developed method has been applied to a facile synthesis of a C2 symmetric bis-triarylmethane in which the two triarylmethanes were bridged through piperzine. The copper(II) bromide catalysis led to C-C bond formation at the C(5) position when the reacting partner was imidazole. In contrast, C-N bond formation took place with benzimdazole or 2-methylbenzimidazole.     

Synthesis,Characterization, and Possible Applications of ZnO Nanocrystals

ZnO nanocrystals are synthesized using the quenching method. The properties of the grown nanocrystals are studied using ultraviolet-vis spectroscopy, x-ray diffraction, photoluminescence, electron diffraction, energy dispersive x-ray spectroscopy, and high resolution transmission electron microscopy. Current-voltage characteristics of the prepared samples are studied for investigating the possible application of the samples as switch and memristor.     

Carbon monoxide isotope enrichment and separation by pressure swing adsorption

Simulations of three different 3-bed 3-step pressure swing adsorption (PSA) cycles were carried out to study the enrichment and recovery of ¹⁴CO from an isotopic mixture of ¹⁴CO, ¹³CO and ¹²CO using NaX zeolite. Each PSA cycle included feed pressurization/feed (FP/P), heavy reflux (HR) and countercurrent depressurization (CnD) steps; they differed only in the way the CnD step was carried out: PSA Cycle I was carried out under total reflux (i.e., with no ¹⁴CO heavy product production); PSA Cycle II was carried out with discontinuous ¹⁴CO heavy product production; and PSA Cycle III was carried out with continuous ¹⁴CO heavy product production. The effects of the CnD step valve coefficient (c _v ), heavy reflux ratio (R _R ), and cycle time (t _cyc ) on the PSA process performance were determined in terms of the ¹⁴CO enrichment, ¹⁴CO recovery and CO feed throughput. The results showed that there was essentially no limit to the extent of the ¹⁴CO enrichment, despite the inherently low ¹⁴CO/¹²CO (1.05) and ¹⁴CO/¹³CO (1.12) separation factors for these isotopes on NaX zeolite. Under total reflux an optimum c _v was found for the CnD step and ¹⁴CO enrichments as high as 152 were obtained. Using the optimum c _v under finite reflux, a ¹⁴CO enrichment approaching 20 and a ¹⁴CO recovery approaching 100 % were easily achieved with discontinuous (PSA Cycle II) or continuous (PSA Cycle III) ¹⁴CO heavy product production. There was essentially no difference in the performance of PSA Cycles II and III, a counterintuitive result. The ¹⁴CO enrichment and the ¹⁴CO recovery both increased with decreasing CO feed throughputs and higher R _R , which were always very close to unity.     

Mismatches Improve the Performance of Strand‐Displacement Nucleic Acid Circuits

Catalytic hairpin assembly (CHA) has previously proven useful as a transduction and amplification method for nucleic acid detection. However, the two hairpin substrates in a CHA circuit can potentially react non‐specifically even in the absence of a single‐stranded catalyst, and this non‐specific background degrades the signal‐to‐noise ratio. The introduction of mismatched base pairs that impede uncatalyzed strand exchange reactions led to a significant decrease of the background signal, while only partially damping the signal in the presence of a catalyst. Various types and lengths of mismatches were assayed by fluorimetry, and in many instances, our MismatCHA designs yielded 100‐fold increased signal‐to‐background ratios compared to a ratio of 4:1 with the perfectly matched substrates. These observations could be of general utility for the design of non‐enzymatic nucleic acid circuits.     

Emerging Bottom-Up Strategies for the Synthesis of Graphene Nanoribbons and Related Structures

The solution-phase synthesis is one of the most promising strategies for the preparation of well-defined graphene nanoribbons (GNRs) in large scale. To prepare high quality, defect-free GNRs, cycloaromatization reactions need to be very efficient, proceed without side reaction and mild enough to accommodate the presence of various functional groups. In this Minireview, we present the latest synthetic approaches for the synthesis of GNRs and related structures, including alkyne benzannulation, photochemical cyclodehydrohalogenation, Mallory and Pd- and Ni-catalyzed reactions.     

Emerging Bottom‐Up Strategies for the Synthesis of Graphene Nanoribbons and Related Structures

The solution‐phase synthesis is one of the most promising strategies for the preparation of well‐defined graphene nanoribbons (GNRs) in large scale. To prepare high quality, defect‐free GNRs, cycloaromatization reactions need to be very efficient, proceed without side reaction and mild enough to accommodate the presence of various functional groups. In this Minireview, we present the latest synthetic approaches for the synthesis of GNRs and related structures, including alkyne benzannulation, photochemical cyclodehydrohalogenation, Mallory and Pd‐ and Ni‐catalyzed reactions.     

Effect of the alpha-methyl substituent on chemoselectivity in esterase-catalyzed hydrolysis of S-acetyl sulfanylalkanoates

The isomeric compounds 1 and 3, which differ only in the position of a methyl substituent, give opposite chemoselectivities in an esterase-catalyzed hydrolysis reaction. The esterase was chemoselective for the oxoester in 1, but for the thiol ester group in 3. A high enantioselectivity was observed for both 1 and 3.