Spin–orbit coupling gives rise to a range of spin-charge interconversion phenomena in nonmagnetic systems where certain spatial symmetries are reduced or absent. Chirality-induced spin-selectivity ...(CISS), a term that generically refers to a spin-dependent electron transfer in nonmagnetic 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 derive a set of geometrical conditions for this effect to appear, hinting at the fundamental role of symmetries beyond otherwise relevant quantitative issues. 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, by extension, to the possible appearance of CISS. It turns out that standalone metallic nanocontacts can exhibit spin-polarization when relative rotations which reduce the symmetry are introduced. As a corollary, molecular junctions with achiral molecules can also exhibit spin-polarization along the direction of transport, provided that the whole junction is chiral in a specific way. This formalism also allows the prediction of qualitative changes of 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 within the single-particle framework.
Stroke is a highly heterogeneous disorder with distinct subtypes, each presenting specific clinical aspects. Information on prognosis of ischemic stroke subtypes help to improve clinical management ...and rehabilitation treatments.
Summarize findings of studies on outcome in stroke subtypes categorized by use of the Oxfordshire Community Stroke Project (OCSP) classification.
Systematic review.
Not applicable.
Adult post-stroke patients.
Systematic literature research of five databases was undertaken to identify relevant studies. Outcomes were examined in terms of impairment, activity restriction and participation restriction. Quality of Life and mortality was also examined for each study.
Sixteen studies met inclusion criteria. Most studies measure outcome in terms of activity limitations and participation restriction. Only one study measures impairment. TACI group have poor outcomes in comparison with other groups. Outcomes of LACI, PACI and POCI groups are controversial.
Stroke subtype is a factor influencing outcome. However, differences among groups, overall in terms of impairment, should be further investigated.
Different prognosis of stroke subtypes may imply different rehabilitation managements.
We report on the chemical design of chiral molecular junctions with stress‐dependent conductance, whose helicity is maintained during the stretching of a single molecule junction due to the stapling ...of both ends of the inner helix. In the reported compounds, different conductive pathways are observed, with clearly different conductance values and plateau‐length distributions, attributed to different conformations of the helical structures. The large chiro‐optical responses and the potential use of these molecules as unimolecular spin filters have been theoretically proved using state‐of‐the‐art Density Functional Theory (DFT) calculations, including a fully ab‐initio estimation of the CISS‐originating spin polarization which is done, for the first time, for a realistic molecular system.
A stapled chiral helical single‐molecule potentiometer based on ortho‐oligophenylethynylene skeleton is described. Its stretching during STM measurements promotes different conductive pathways, attributed to different conformations of the helical scaffold, while maintaining the helicity. State of the art calculations on polarization pave the way to use these structures as unimolecular spin filters.
Diamond is a promising candidate material for high power, high temperature and high frequency electronics. Boron is well known as a shallow acceptor in diamond. Recently diamond has been successfully ...shallow n-type doped by introducing an excess of deuterium in high quality B doped diamond, enabling a reversible p-type to n-type conversion of B doped diamond. However, the nature of this new shallow donor has been the subject of debate. We calculate the properties of boron and its complexes with hydrogen in diamond, using accurate
ab
initio plane wave Density Functional Theory (DFT) methods, and show that BH
2 centres are stable with small binding energies of 0.23 to 0.71 eV, consistent with experimentally observed dissociation of the new donor at relatively low temperatures of 200 °C, and explain the two-step deuteration process in high quality boron doped diamond.
Our
ab
initio Plane Wave periodic supercell DFT theory calculations confirm the existence of a BH induced level at
E
c
–
0.96 eV. We further show that the BH
2 centre possesses a very deep donor level, excluding the possibility of BH
2 doping the BH impurity band previously suggested.
To facilitate experimental determination of the nature of the new shallow donor, we determine the Local Vibrational Modes of BH and BH
2 centres in different charge states, together with isotope shifts, which may be compared with experiment, towards establishing the nature of the new donor.
Abstract Spin-charge inter-conversion mediated by spin-orbit coupling can lead to finite magnetoconductance in two-terminal molecular nanojunctions under non-equilibrium conditions. Here, we ...demonstrate how such a finite magnetoconductance can emerge in model two-terminal molecular nanojunctions by means of density functional theory based transport calculations with spin-orbit coupling in a first-order perturbation approximation. The junctions are built from the two chiral partners of an idealized helical molecule and tungsten or gold electrodes with two layers of magnetic nickel at the interface of the drain electrodes. Using Au source electrodes and a low applied bias of 0.1 V, we find percentage relative magnetoconductance values in excess of the lower bound reported in recent low-temperature, low-bias, experiments. The left-handed molecule is seen to exhibit greater magnetoconductance than its right-handed chiral partner for both Au and W source electrodes, thus demonstrating that our calculations can also exhibit enantioselectivity.
This book explores the long-unstudied relationship between religion and human security throughout the world. The 1950s marked the beginning of a period of extraordinary religious revival, during ...which religious political-parties and non-governmental organizations gained power around the globe. Until now, there has been little systematic study of the impact that this phenomenon has had on human welfare, except of a relationship between religious revival to violence. The chapters in this book show that religion can have positive as well as negative effects on human wellbeing. They address a number of crucial questions about the relationship between religion and human security: Under what circumstances do religiously motivated actors tend to advance human welfare, and under what circumstances do they tend to threaten it? Are members of some religious groups more likely to engage in welfare-enhancing behavior than in others? Do certain state policies tend to promote security-enhancing behavior among religious groups while other policies tend to promote security-threatening ones? In cases where religious actors are harming the welfare of a population, what responses could eliminate that threat without replacing it with another? This book shows that many states tend to underestimate the power of religious organizations as purveyors of human security. Governments overlook both the importance of human security to their populations and the religious groups who could act as allies in securing the welfare of their people. This book offers a variety of theoretical perspectives on the nuanced relationship between religion and human security. Through case studies ranging from Turkey, Egypt, and Pakistan, to the United States, Northern Ireland, and Zimbabwe, it provides important suggestions to policy makers of how to begin factoring the influence of religion into their evaluation of a population's human security and into programs designed to improve human security around the globe.
We report a first-principles investigation of the structural, electronic and magnetic properties of cobalt–vacancy defect complexes in graphene, within the framework of density-functional theory ...(DFT), incorporating DFT+U. Specifically, we consider the interactions of cobalt and vacancies in graphene, at varying separations and sub-lattices. We show that it is energetically favorable for substitutional Co in graphene to trap an additional vacancy in graphene, forming a Co–vacancy complex. In all the configurations considered, the most stable configuration is when the Co atom is embedded in a divacancy. The magnetic moment induced on the cobalt atom varies as the vacancy–cobalt separation changes, depending not only on the separation, but also on the sub-lattice of the vacancy relative to cobalt. Furthermore, for each separation and sub-lattice considered, the linear density of states of graphene is modified such that Dirac point is either not discernible or has shifted above the Fermi energy. Since individual vacancies or transition metal (TM) atoms, such as cobalt in graphene, have mostly been studied in isolation up to now, ignoring possible transition metal–vacancy interactions, these results have important implications to the fundamental understanding of TM–vacancy defect interactions in graphene.
This volume explores the decision by the government of Egypt in the 1970s to constitutionalize Islamic shari?a and discusses its impact on Egypt's constitutional jurisprudence. The author, who is ...trained in Islamic intellectual history and comparative law, begins by examining the evolution of Sunni Islamic legal theory and describes competing theories of Islamic law that co-exist in modern Egypt. The book then explores how the Supreme Constitutional Court of Egypt has developed its own approach to interrpreting shari?a—one that permits the Court to argue that shari'a principles are consistent with international human rights norms. The book concludes with a discussion of the public reception of the Court's theory.This book will be essential for anyone interested in the evolution of Islamic law, the development of constitutional thought in the Middle East, or the relationship between Islam and human rights.
