Anomalous temperature dependence of elastic constants in the nematic phase of binary mixtures made of rodlike and bent-core molecules

We report on two anomalous trends in the temperature dependences of the splay (K11) and bend (K33) elastic constants in the nematic (N) phase of mixtures of compounds with rodlike (R) and bent-core (BC) molecules: As the sample is cooled from the isotropic to N transition point, (i) K33 increases, attains a maximum value and then decreases, and (ii) close to the N to smectic A (SmA) transition point, K11 decreases sharply. At higher temperatures the bow axes of BC molecules are aligned along the director n^, strongly favoring a bend distortion of n^ as the orientational order parameter is increased. Close to the N-SmA transition point the smecticlike short-range order builds up, and the arrow axes of BC molecules are aligned along n^, facilitating a splay distortion of n^. A simple model calculation brings out the anomalous trend in K33

Zinc mediated allylation of aldehydes and ketones using allyl bromides and commercial zinc dust. The issue of regio- and stereoselectivity

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Feasibility of detecting myocardial infarction in the sheep fetus using late gadolinium enhancement CMR imaging

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.Background Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging has enabled the accurate assessment of myocardial infarction (MI). However, LGE CMR has not been performed successfully in the fetus, where it could be useful for animal studies of interventions to promote cardiac regeneration. We believe that LGE imaging could allow us to document the presence, extent and effect of MI in utero and would thereby expand our capacity for conducting fetal sheep MI research. We therefore aimed to investigate the feasibility of using LGE to detect MI in sheep fetuses. Methods Six sheep fetuses underwent a thoracotomy and ligation of a left anterior descending (LAD) coronary artery branch; while two fetuses underwent a sham surgery. LGE CMR was performed in a subset of fetuses immediately after the surgery and three days later. Early gadolinium enhancement (EGE) CMR was also performed in a subset of fetuses on both days. Cine imaging of the heart was performed to measure ventricular function. Results The imaging performed immediately after LAD ligation revealed no evidence of infarct on LGE (n=3). Two of four infarcted fetuses (50%) showed hypoenhancement at the infarct site on the EGE images. Three days after the ligation, LGE images revealed a clear, hyper-enhanced infarct zone in four of the five infarcted fetuses (80%). No hyper-enhanced infarct zone was seen on the one sham fetus that underwent LGE CMR. No hypoenhancement could be seen in the EGE images in either the sham (n=1) or the infarcted fetus (n=1). No regional wall motion abnormalities were apparent in two of the five infarcted fetuses. Conclusion LGE CMR detected the MI three days after LAD ligation, but not immediately after. Using available methods, EGE imaging was less useful for detecting deficits in perfusion. Our study provides evidence for the ability of a non-invasive tool to monitor the progression of cardiac repair and damage in fetuses with MI. However, further investigation into the optimal timing of LGE and EGE scans and improvement of the sequences should be pursued with the aim of expanding our capacity to monitor cardiac regeneration after MI in fetal sheep

Silica gel-supported zinc borohydride. Part 3. Regioselective reductive cleavage of methylenecycloalkane oxides to the less-substituted alcohols

Highly selective reductive cleavage of methylenecycloalkane oxides to less-substituted alcohols has been achieved by a simple procedure using silica gel supported zinc borohydride in tetrahydrofuran

Selective reduction of carboxylic acids with zinc borohydride in the presence of trifluoroacetic anhydride

A simple and convenient procedure for the reduction of carboxylic acids to the corresponding alcohols has been developed using a solution of zinc borohydride in 1,2-dimethoxyethane in the presence of trifluoroacetic anhydride

Two-carbon ring expansion through free cyclobutylcarbinyl radical fragmentation

Fragmentation of cyclobutylcarbinyl radicals in suitably substituted cyclobutane derivatives leads to functionalised fused seven- and eight-membered ring systems by way of two-carbon ring expansion

Regio- and stereo-selective reductive cleavage of epoxides with zinc borohydride supported on silica gel

Reductive cleavage of unsymmetrical alkyl-substituted epoxides to less substituted alcohols has been achieved in a simple procedure using zinc borohydride supported on silica gel

Ion exchange resin-mediated hydrolytic cleavage of α-nitroepoxides. Simple one-pot synthesis of α-hydroxyketones

α-Nitroepoxides are cleaved in an aqueous suspension with Dowex-50 to furnish α-hydroxyketones in excellent yields

Use of zinc borohydride as an efficient and highly selective reducing agent. Selective reduction of ketones and conjugated aldehydes over conjugated enones

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