A group-theoretic approach to the origin of chirality-induced spin selectivity in non-magnetic molecular junctions

Spin-orbit coupling gives rise to a range of spin-charge interconversion phenomena in non-magnetic systems where spatial symmetries are reduced or absent. Chirality-induced spin selectivity (CISS), a term that generically refers to a spin-dependent electron transfer in non-magnetic chiral systems, is one such case, appearing in a variety of seemingly unrelated situations ranging from inorganic materials to molecular devices. In particular, the origin of CISS in molecular junctions is a matter of an intense current debate. Here we contend that the necessary conditions for the CISS effect to appear can be generally and fully understood on the basis of a complete symmetry analysis of the molecular junction, and not only of the molecule. Our approach, which draws on the use of point-group symmetries within the scattering formalism for transport, shows that electrode symmetries are as important as those of the molecule when it comes to the emergence of a spin-polarization and, therefore, a possible appearance of CISS. It turns out that standalone metallic nanocontacts can exhibit spin-polarization when relative rotations are introduced which reduce the symmetry. As a corollary, molecular junctions with $\textbf{achiral}$ molecules can also exhibit spin polarization along the direction of transport, provided that the whole junction is chiral. This formalism also allows to predict the qualitative changes on the spin-polarization upon substitution of a chiral molecule in the junction with its enantiomeric partner. Quantum transport calculations based on density functional theory corroborate all of our predictions and provide further quantitative insight.Comment: 19 pages, 4 figures, 1 tabl

Regional vulnerability of the hippocampus to repeated motor activity deprivation

Spontaneous vertical and horizontal exploratory movements are integral components of rodent behavior. Little is known, however, about the structural and functional consequences of restricted spontaneous exploration. Here, we report two experiments to probe whether restriction in vertical activity (rearing) in rats could induce neuro-hormonal and behavioral disturbances. Rearing movements in rats were deprived for 3 h/day for 30 consecutive days by placing the animal into a circular tunnel task. Rats temporarily deprived of rearing behavior showed elevated plasma corticosterone levels but no detectable psychological distress and/or anxiety-related behavior within an elevated plus maze. However, rats emitted a greater number of 22-kHz ultrasonic vocalizations and spent significantly more time vocalizing than controls when deprived of their rearing behavior. Despite intact spatial performance within wet- and dry-land spatial tasks, rearing-deprived rats also exhibited a significant alteration in search strategies within both spatial tasks along with reduced volume and neuron number in the hippocampal subregion CA2. These data suggest a new approach to test the importance of free exploratory behavior in endocrine and structural manifestations. The results support a central role of the CA2 in spontaneous exploratory behavior and vulnerability to psychological stress. © 2015 Elsevier B.V

Laser-Beam-Patterned Topological Insulating States on Thin Semiconducting MoS2

Identifying the two-dimensional (2D) topological insulating (TI) state in new materials and its control are crucial aspects towards the development of voltage-controlled spintronic devices with low-power dissipation. Members of the 2D transition metal dichalcogenides have been recently predicted and experimentally reported as a new class of 2D TI materials, but in most cases edge conduction seems fragile and limited to the monolayer phase fabricated on specified substrates. Here, we realize the controlled patterning of the 1T′ phase embedded into the 2H phase of thin semiconducting molybdenum-disulfide by laser beam irradiation. Integer fractions of the quantum of resistance, the dependence on laser-irradiation conditions, magnetic field, and temperature, as well as the bulk gap observation by scanning tunneling spectroscopy and theoretical calculations indicate the presence of the quantum spin Hall phase in our patterned 1T′ phasesThe work carried out at Aoyama Gakuin University was partly supported by a grant for private universities and a Grant-in-Aid for Scientific Research (JP15K13277) awarded by MEXT. The work at the University of Tokyo was partly supported by Grantin-Aid for Scientific Research (JP17K05492, JP18H04218 and JP19H00652). J. J. P. and S. P. acknowledge Spanish MINECO through Grant No. FIS2016-80434-P, the Fundación Ramón Areces, the María de Maeztu Program for Units of Excellence in R&D (MDM-2014- 0377), the Comunidad Autónoma de Madrid through NANOMAGCOST Program, and the European Union Seventh Framework Programme under Grant Agreement No. 604391 Graphene Flagship. S. P. acknowledges the computer resources and assistance provided by the Centro de Computación Científica of the Universidad Autónoma de Madrid. S. P. was also supported by the VILLUM FONDEN via the Center of Excellence for Dirac Materials (Grant No. 11744). D. M. and E. G.-M. gratefully acknowledge support from the Graphene Flagship Graphene Core2 Contract No. 785219. E. G.-M also acknowledges IJCI-2017-32297 from Spanish MINECO/AE

Investigation of presence, distribution and flight period of oak leaf roller moth, Tortrix viridana (Lep.: Tortricidae) using pheromone traps in Kurdistan province

Forests cover about 5,200,000 hectares of the west of Iran, from which 500,000 hectares are located in Kurdistan province. One of the most important pests in the oak forests of this province is oak leaf roller moth, Tortrix viridana L. (Lep.: Tortricidae). This pest significantly damages the oak forest each year. Using pheromone trap is one of the suitable methods for monitoring of this pest. In this work, distribution and flight period of the pest were studied by pheromone traps during two years. Fifteen regions were trapped at the equal distances (40 km) from Kamyaran (south west of Kurdistan province) to Baneh (north west of Kurdistan province) to investigate the presence and distribution of this moth. Also, a region located between Sanandaj and Marivan was selected to study the flight period. Some traps were established in this region and checked every two days. Investigation of pest distribution showed that oak leaf roller moth was present all over the sites from Kamyaran to Baneh. Different populations of moth were trapped in all over the sites. The highest population was trapped in Colit region (mid-west of Kurdistan province). The study of flight period showed that first moths were trapped on May, 16th and the peak of the flight took place on May, 21st and finally the last moths were trapped on June, 24th. Therefore, adults activated during 40 days; mating and oviposition occurred during this period. Incubation period lasted 9 months and activation of larvae was coincident with flashing of foliar buds

Microfluidic systems for the analysis of the viscoelastic fluid flow phenomena in porous media

In this study, two microfluidic devices are proposed as simplified 1-D microfluidic analogues of a porous medium. The objectives are twofold: firstly to assess the usefulness of the microchannels to mimic the porous medium in a controlled and simplified manner, and secondly to obtain a better insight about the flow characteristics of viscoelastic fluids flowing through a packed bed. For these purposes, flow visualizations and pressure drop measurements are conducted with Newtonian and viscoelastic fluids. The 1-D microfluidic analogues of porous medium consisted of microchannels with a sequence of contractions/ expansions disposed in symmetric and asymmetric arrangements. The real porous medium is in reality, a complex combination of the two arrangements of particles simulated with the microchannels, which can be considered as limiting ideal configurations. The results show that both configurations are able to mimic well the pressure drop variation with flow rate for Newtonian fluids. However, due to the intrinsic differences in the deformation rate profiles associated with each microgeometry, the symmetric configuration is more suitable for studying the flow of viscoelastic fluids at low De values, while the asymmetric configuration provides better results at high De values. In this way, both microgeometries seem to be complementary and could be interesting tools to obtain a better insight about the flow of viscoelastic fluids through a porous medium. Such model systems could be very interesting to use in polymer-flood processes for enhanced oil recovery, for instance, as a tool for selecting the most suitable viscoelastic fluid to be used in a specific formation. The selection of the fluid properties of a detergent for cleaning oil contaminated soil, sand, and in general, any porous material, is another possible application

Nucleobindin-1 regulates ECM degradation by promoting intra-Golgi trafficking of MMPs.

Matrix metalloproteinases (MMPs) degrade several ECM components and are crucial modulators of cell invasion and tissue organization. Although much has been reported about their function in remodeling ECM in health and disease, their trafficking across the Golgi apparatus remains poorly understood. Here we report that the cis-Golgi protein nucleobindin-1 (NUCB1) is critical for MMP2 and MT1-MMP trafficking along the Golgi apparatus. This process is Ca2+-dependent and is required for invasive MDA-MB-231 cell migration as well as for gelatin degradation in primary human macrophages. Our findings emphasize the importance of NUCB1 as an essential component of MMP transport and its overall impact on ECM remodeling. © 2020 Pacheco-Fernandez et al