Missing Link between Helical Nano‐ and Microfilaments in B4 Phase Bent‐Core Liquid Crystals,and Deciphering which Chiral Center Controls the Filament Handedness

The range of possible morphologies for bent‐core B4 phase liquid crystals has recently expanded from helical nanofilaments (HNFs) and modulated HNFs to dual modulated HNFs, helical microfilaments, and heliconical‐layered nanocylinders. These new morphologies are observed when one or both aliphatic side chains contain a chiral center. Here, the following questions are addressed: which of these two chiral centers controls the handedness (helicity) and which morphology of the nanofilaments is formed by bent‐core liquid crystals with tris‐biphenyl diester core flanked by two chiral 2‐octyloxy side chains? The combined results reveal that the longer arm of these nonsymmetric bent‐core liquid crystals controls the handedness of the resulting dual modulated HNFs. These derivatives with opposite configuration of the two chiral side chains now feature twice as large dimensions compared to the homochiral derivatives with identical configuration. These results are supported by density functional theory calculations and stochastic dynamic atomistic simulations, which reveal that the relative difference between the para‐ and meta‐sides of the described series of compounds drives the variation in morphology. Finally, X‐ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) data also uncover the new morphology for B4 phases featuring p2/m symmetry within the filaments and less pronounced crystalline character.     

Towards Recyclable Nanoporous Polymer Membranes for the Synthesis of One-dimensional Nanoscale Gold Colloids

Proof-of-concept studies towards recyclable nanoporous track-etched polymer membranes for template-synthesis of one-dimensional colloidal gold rods indicate that surfactant-capped gold nanorods can be synthesised within and isolated from polyethylene terephthalate (Lavsan) membranes using organic solvents with or without sonication. Thereafter, the same Lavsan membrance can be re-used for at least one to two additional synthetic cycles. An erratum to this article can be found at     

Comparison of isolation procedures for Mexican oregano oil

The influence of distillation time on the composition of Mexican oregano oil was investigated. It was observed that the order of recovery of the components was determined by their solubility when water is in contact with the plant material as in hydrodistillation and simultaneous distillation-solvent extraction, while in steam distillation the order was determined by their boiling points. The three methods produced the same composition. The oil obtained by extraction method had higher proportion of hydrocarbons and lower amount of p-cymene. As a result of this investigation it was shown that this compound was partly an artefact of distillation.     

Synthesis and Structure of 1,5-Di-(Ethylphenyl)-1,5-Dimethyl-3,3,7,7-Tetraphenylcycloterasiloxane: a Novel Cyclotetramer

Herein we report the first synthesis of 1,5- di-(ethylphenyl)-1,5-dimethyl-3,3,7,7-tetraphenylcyclotetrasiloxane using a new ‘One Pot’ procedure as recently reported for the preparation of strictly alternating 1,1,5,5-tetramethyl-3,3,7,7-tetraphenylcyclotetrasiloxane by the heterofunctional condensation of diphenylsilanediol with (phenylethyl)methyldichlorosilane in the presence of the ter tiary amine, triethylamine (Nguyen et al. Silicon 6:21–26 2014). The prepared 1,5-di-(ethylphenyl)-1,5-dimethyl-3,3,7,7-tetraphenylcyclotetrasi loxane was fully characterized by single-crystal X-ray diffraction, ¹H, ¹³C and ²⁹Si nuclear magnetic resonance spectroscopy, elemental analysis, mass spectroscopy, thermogravimetric analysis and differential scanning calori metric studies.     

Comparison of physicochemical pretreatments of banana peels for bioethanol production

Pretreatments with different concentrations of sulfuric acid (0, 0.5, and 1% v/v) and temperatures (28 and 121 °C at 103 kPa in an autoclave) were performed on banana peels (BP) milled by mechanical grinding and grinding in a blender as well as without grinding. Cellulose, hemicellulose, lignin, ash, and total and reducing sugar contents were evaluated. The highest yields of cellulose enzymatic hydrolysis (99%) were achieved with liquefied autoclaved BP treated with 0.5 and 1% acid after 48 h of hydrolysis. Ethanol production by Kluyveromyces marxianus fermentation was assayed using hydrolyzed BP at 10, 15, and 20% (w/w). The highest ethanol level (21 g/L) was reached after 24 h of fermentation with 20% (w/w) BP. Kinetics of the consumption of reducing sugars under this fermentation condition demonstrates the presence of a lag period (about 8 h). Thus, BP are a good source for ethanol production.     

The Strain Index (SI) and Threshold Limit Value (TLV) for Hand Activity Level (HAL): risk of carpal tunnel syndrome (CTS) in a prospective cohort

A cohort of 536 workers was enrolled from 10 diverse manufacturing facilities and was followed monthly for six years. Job physical exposures were individually measured. Worker demographics, medical history, psychosocial factors, current musculoskeletal disorders (MSDs) and nerve conduction studies (NCS) were obtained. Point and lifetime prevalence of carpal tunnel syndrome (CTS) at baseline (symptoms + abnormal NCS) were 10.3% and 19.8%. During follow-up, there were 35 new CTS cases (left, right or both hands). Factors predicting development of CTS included: job physical exposure (American conference of governmental industrial hygienists Threshold Limit Value (ACGIH TLV) for Hand Activity Level (HAL) and the Strain Index (SI)), age, BMI, other MSDs, inflammatory arthritis, gardening outside of work and feelings of depression. In the adjusted models, the TLV for HAL and the SI were both significant per unit increase in exposure with hazard ratios (HR) increasing up to a maximum of 5.4 (p = 0.05) and 5.3 (p = 0.03), respectively; however, similar to other reports, both suggested lower risk at higher exposures. Data suggest that the TLV for HAL and the SI are useful metrics for estimating exposure to biomechanical stressors. PRACTITIONER SUMMARY: This study was conducted to determine how well the TLV for HAL and the SI predict risk of CTS using a prospective cohort design with survival analysis. Both the TLV for HAL and the SI were found to predict risk of CTS when adjusted for relevant covariates.     

Études sur l’efficacité et la durabilité de deux traitements appliqués à un calcaire

Ce travail présente une étude en laboratoire sur l’efficacité et la durabilité de deux produits de traitement des pierres: un hydrofuge de surface (à base de résine silicone) et un produit de protection superficielle contre les agents atmosphériques et la pollution (qui se compose d’un polymère acrylique, d’un solvant et d’une cire synthétique). La pierre étudiée était un calcaire d’Ançã, très utilisé dans le centre du pays et dont la conservation dans des monuments historiques pose de graves problèmes. Les méthodes d’essai utilisées pour la caractérisation du calcaire ont été celles recommandées par la Commission 25 PEM (Protection et Erosion des Monuments) de la RILEM. Dans le but d’évaluer l’efficacité et la durabilité du traitement acrylique, des éprouvettes traitées et non-traitées (pour servir de comparaison) ont été soumises aux essais suivants: —Action de la lumière; action de l’eau et de la lumière par exposition dans un appareil de vieillissement du type arc voltaïque; action de l’anhydride sulfureux; et essai de cristallisation. Sur les éprouvettes traitées avec le produit hydrofuge siliconique on a réalisé les mêmes essais, sauf ceux concernant la cristallisation et l’action de l’anhydride sulfureux. Les effets du vieillissement causé par ces essais ont été appréciés par observation visuelle périodique et par les déterminations suivantes: angle de contact, absorption par gouttes, absorption d’eau pendant 48 h, coefficient d’absorption d’eau (capillarité), et absorption d’eau par hygroscopicité. Finalement on présente une appréciation des résultats obtenus.