Kerr effect in the isotropic melt of smectic polymer

Electric birefringence in the isotropic melt of a comb-like polyacrylate with mesogenic cyanobiphenyl side groups has been studied. A fraction with the degree of polymerization 200, which forms a smectic mesophase, has been considered. The change in the character of the temperature dependence of the Kerr constant has been revealed in the isotropic phase above the smectic–isotropic phase transition temperature. This effect is explained by the change in the character of short-range order in the isotropic–isotropic phase transition.     

Sorption and Separation of Optical Isomers of 2-Butanol by Chiral Porous Coordination Polymers

Theoretical and Experimental Chemistry - It was shown that porous coordination polymers (PCPs) of 3d metals containing chiral centers in fragments of deprotonated (S)-lactic and (R)-aspartic acid...     

Nonvisual Opsins and the Regulation of Peripheral Clocks by Light and Hormones

The molecular clock machinery is conserved throughout evolution. However, how environmental cues are perceived has evolved in such a way that peripheral clocks in mammals require a variety of signals, including hormones. On the other hand, in nonmammalian cells able to directly detect light, light seems to play a major role in the synchronization of the clock. The interaction between perception of circadian light by nonvisual opsins and hormones will be discussed under the perspective of clock synchronization at the molecular level.     

Dunaliella tertiolecta (Chlorophyta) Avoids Cell Death Under Ultraviolet Radiation By Triggering Alternative Photoprotective Mechanisms

The effect of different ultraviolet radiation (UVR) treatments combining PAR (P), UVA (A) and UVB (B) on the molecular physiology of Dunaliella tertiolecta was studied during 6 days to assess the response to chronic UVR exposure. UVR reduced cell growth but did not cause cell death, as shown by the absence of SYTOX Green labeling and cellular morphology. However, caspase‐like enzymatic activities (CLs), (regarded as cell death proteases), were active even though the cells were not dying. Maximal quantum yield of fluorescence (F_v/F_m) and photosynthetic electron transport rate (ETR) dropped. Decreased nonphotochemical quenching (NPQ) paralleled a drop in xanthophyll cycle de‐epoxidation under UVB. Reactive oxygen species (ROS) and D1 protein accumulation were inversely correlated. PAB exhibited elevated ROS production at earlier times. Once ROS decayed, D1 protein recovered two‐fold compared with P and PA at later stages. Therefore, PsbA gene was still transcribed, suggesting ROS involvement in D1 recovery by its direct effect on mRNA‐translation. We add evidence of an UVB‐induced positive effect on the cells when P is present, providing photoprotection and resilience, by means of D1 repair. This allowed cells to survive. The photoprotective mechanisms described here (which are counterintuitive in principle) conform to an important ecophysiological response regarding light stress acclimation.     

Selective assembly of Au-Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticle hetero-dimers

Hetero-dimeric magnetic nanoparticles of the type Au-Fe₃O₄ have been synthesised from separately prepared, differently shaped (spheres and cubes), monodisperse nanoparticles. This synthesis was achieved by the following steps: (a) Mono-functionalising each type of nanoparticles with aldehyde functional groups through a solid support approach, where nanoparticle decorated silica nanoparticles were fabricated as an intermediate step; (b) Derivatising the functional faces with complementary functionalities (e.g. amines and carboxylic acids); (c) Dimerising the two types of particles via amide bond formation. The resulting hetero-dimers were characterised by high-resolution TEM, Fourier transform IR spectroscopy and other appropriate methods.

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Graphical Abstract Nano-LEGO: Assembling two types of separately prepared nanoparticles into a hetero-dimer is the first step towards complex nano-architectures. This study shows a solid support approach to combine a gold and a magnetite nanocrystal.