Lehmann rotation of cholesteric droplets subjected to a temperature gradient: role of the concentration of chiral molecules

International audienceWe present a systematic study of the Lehmann rotation of cholesteric droplets subjected to a temperature gradient when the concentration of chiral molecules is changed. The liquid crystal chosen is an eutectic mixture of 8CB and 8OCB doped with a small amount of the chiral molecule R811. The angular velocity of the droplets strongly depend on their size and on the concentration of chiral molecules. The Lehmann coefficient is estimated by using three different methods. Our results are consistent with a Lehmann coefficient proportional to the concentration of chiral molecules. We additionally show the existence of a critical size of the droplets below which they change texture and stop rotating

Thermal and Optical Characterization of Undoped and Neodymium-Doped Y3ScAl4O12 Ceramics

Y3–3xNd3xSc1Al4O12 (x = 0, 0.01, and 0.02) ceramics were fabricated by sintering at high temperature under vacuum. Unit cell parameter refinement and chemical analysis have been performed. The morphological characterization shows micrograins with no visible defects. The thermal analysis of these ceramics is presented, by measuring the specific heat in the temperature range from 300 to 500 K. Their values at room temperature are in the range 0.81–0.90 J g1–K–1. The thermal conductivity has been determined by two methods: by the experimental measurement of the thermal diffusivity by the photopyroelectric method, and by spectroscopy, evaluating the thermal load. The thermal conductivities are in the range 9.7–6.5 W K–1 m–1 in the temperature interval from 300 to 500 K. The thermooptic coefficients were measured at 632 nm by the dark mode method using a prism coupler, and the obtained values are in the range 12.8–13.3 × 10–6 K–1. The nonlinear refractive index values at 795 nm have been evaluated to calibrate the nonlinear optical response of these materials.This work is supported by the Spanish Government under projects MAT2011-29255-C02-01-02, MAT2013-47395-C4-4-R, and the Catalan Government under project 2014SGR1358. It was also funded by the European Commission under the Seventh Framework Programme, project Cleanspace, FP7-SPACE-2010-1-GA No. 263044

An early diagnosis is not the same as a timely diagnosis of Parkinson's disease

referee-status: Indexed referee-response-35490: 10.5256/f1000research.15815.r35490, Matthew J. Farrer, Djavad Mowafhagian Centre for Brain, University of British Columbia, Vancouver, British Columbia, Canada, 18 Jul 2018, version 1, indexed referee-response-35489: 10.5256/f1000research.15815.r35489, Mayela Rodriguez-Violante, Movement Disorders Clinic, National Institute of Neurology and Neurosurgery, Mexico City, Mexico, 18 Jul 2018, version 1, indexed grant-information: This review was supported by grants from: Parkinson’s UK (G-1606), National Institute for Health Research University College Hospitals Biomedical Research Centre and Bart’s Charity (Preventative Neurology Grant). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. copyright-info: This is an open access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This review was supported by grants from: Parkinson’s UK (G-1606), National Institute for Health Research University College Hospitals Biomedical Research Centre and Bart’s Charity (Preventative Neurology Grant)

Photopyroelectric measurement of thermal effusivity of liquids by sample's thickness scan

A method based on the sample's thickness scan of the amplitude of the photopyroelectric (PPE) signal is proposed as an alternative for thermal effusivity measurement of liquids. The proposed method uses a combined amplitude-phase information and needs the knowledge of the absolute values of the sample's thickness and phase of the signal. The accuracy of the method is similar with that of previously reported frequency-scanned methods, provided an accurate control of the cell's (sample's) thickness is performed. A 479 Ws1/2/m2K room temperature value for the thermal effusivity of silicon oil was found, with a 0.1 μm step thickness control

Additional file 1 of A mutant methionyl-tRNA synthetase-based toolkit to assess induced-mesenchymal stromal cell secretome in mixed-culture disease models

Additional file 1: Fig. S1. Uncropped agarose gel from Figure 1B

Monitoring alpha‐synuclein oligomerization and aggregation using bimolecular fluorescence complementation assays: What you see is not always what you get

Bimolecular fluorescence complementation (BiFC) was introduced a decade ago as a method to monitor alpha-synuclein (alpha-syn) oligomerization in intact cells. Since then, several alpha-syn BiFC cellular assays and animal models have been developed based on the assumption that an increase in the fluorescent signal correlates with increased alpha-syn oligomerization or aggregation. Despite the increasing use of these assays and models in mechanistic studies, target validation and drug screening, there have been no reports that (1) validate the extent to which the BiFC fluorescent signal correlates with alpha-syn oligomerization at the biochemical level; (2) provide a structural characterization of the oligomers and aggregates formed by the BiFC. To address this knowledge gap, we first analysed the expression level and oligomerization properties of the individual constituents of alpha-syn-Venus, one of the most commonly used BiFC systems, in HEK-293 & SH-SY5Y cells from three different laboratories using multiple biochemical approaches and techniques. Next, we investigated the biochemical and aggregation properties of alpha-syn upon co-expression of both BiFC fragments. Our results show that (1) the C-terminal-Venus fused to alpha-syn (alpha-syn-Vc) is present in much lower abundance than its counterpart with N-terminal-Venus fused to alpha-syn (Vn-alpha-syn); (2) Vn-alpha-syn exhibits a high propensity to form oligomers and higher-order aggregates; and (3) the expression of either or both fragments does not result in the formation of alpha-syn fibrils or cellular inclusions. Furthermore, our results suggest that only a small fraction of Vn-alpha-syn is involved in the formation of the fluorescent BiFC complex and that some of the fluorescent signal may arise from the association or entrapment of alpha-syn-Vc in Vn-alpha-syn aggregates. The fact that the N-terminal fragment exists predominantly in an aggregated state also indicates that one must exercise caution when using this system to investigate alpha-syn oligomerization in cells or in vivo. Altogether, our results suggest that cellular and animal models of oligomerization, aggregation and cell-to-cell transmission based on the alpha-syn BiFC systems should be thoroughly characterized at the biochemical level to ensure that they reproduce the process of interest and measure what they are intended to measure