Research Institute for Applied Sciences

Chiral π-conjugated molecules have potential applications in spin-selective organic semiconductors and chiroptical electronic devices that are responsive to circularly polarized light. Their performance is expected to largely depend on how they assemble in the solid state, however, there are limited strategies for controlling the packing structure, particularly in helically-twisted π-conjugated molecules. In this work, a homochiral face-to-face columnar packing arrangement for helicene derivatives was achieved by modifying their helical ends with 2,1,3-thiadiazole structures. The observations provide useful insights into the chiral crystal engineering with helically twisted molecules and the development of chiral organic semiconductor materials.

Spin superfluidity is a phenomenon suitable for long range transport of spin angular momentum and requires rotation of the Néel vector within magnetic easy-plane. Recently, we demonstrated Néel vector rotation induced by spin-orbit torque in a spin-flopped ferrimagnet, which can be regarded as an ideal easy-plane antiferromagnet. However, the detailed dynamics of the Néel vector with respect to material parameters have remained unclear. In this paper, we investigate the effect of damping constant, magnetic anisotropy, current density, thickness and spin diffusion length on Néel vector rotation using atomistic spin simulation. While magnetic anisotropy can be disregarded for current densities well above the threshold, its influence becomes significant near the threshold current density. These results provide important insights into Néel vector rotation and spin superfluidity.

Abstract Let be an arbitrary non‐compact hyperbolic Riemann surface, that is, not the complex plane or punctured plane. Let be , or . We show that, on a Higgs bundle in the ‐Hitchin section over , there always exists a harmonic metric satisfying certain nice properties. Moreover, when the Higgs field has bounded spectral curve with respect to the complete hyperbolic metric on , such a harmonic metric is unique. As a result, we obtain a new proof of the existence and uniqueness of a harmonic metric for Higgs bundles in the ‐Hitchin section over a compact hyperbolic Riemann surface. Moreover, we show an existence result of harmonic metrics for a more general family of Higgs bundles that admit a full holomorphic filtration.

Enhanced de novo lipogenesis mediated by sterol regulatory element–binding proteins (SREBPs) is thought to be involved in nonalcoholic steatohepatitis (NASH) pathogenesis. In this study, we assessed the impact of SREBP inhibition on NASH and liver cancer development in murine models. Unexpectedly, SREBP inhibition via deletion of the SREBP cleavage–activating protein (SCAP) in the liver exacerbated liver injury, fibrosis, and carcinogenesis despite markedly reduced hepatic steatosis. These phenotypes were ameliorated by restoring SREBP function. Transcriptome and lipidome analyses revealed that SCAP/SREBP pathway inhibition altered the fatty acid (FA) composition of phosphatidylcholines due to both impaired FA synthesis and disorganized FA incorporation into phosphatidylcholine via lysophosphatidylcholine acyltransferase 3 (LPCAT3) downregulation, which led to endoplasmic reticulum (ER) stress and hepatocyte injury. Supplementation with phosphatidylcholines significantly improved liver injury and ER stress induced by SCAP deletion. The activity of the SCAP/SREBP/LPCAT3 axis was found to be inversely associated with liver fibrosis severity in human NASH. SREBP inhibition also cooperated with impaired autophagy to trigger liver injury. Thus, excessively strong and broad lipogenesis inhibition was counterproductive for NASH therapy; this will have important clinical implications in NASH treatment.

Hexaazatriphenylene (HAT) derivatives have attracted wide attention because of their electron-deficient nature and unique self-assembly properties. In this work, a facile synthesis method for obtaining HAT derivatives with alternating electron-withdrawing nitrile and electron-donating alkoxy groups (HATCNOCn) is proposed. Crystal structure analysis indicated that HATCNOCn forms a one-dimensional columnar structure via strong π-π interactions. Density functional theory calculations revealed that the edge of HATCNOCn is divided into positively and negatively charged sites owing to the presence of alternating nitrile and alkoxy groups, which would induce strong π-π interactions. Thermal analysis and polarizing optical microscopy revealed that HATCNOCn exhibits columnar liquid-crystal phases. Time-resolved microwave conductivity measurements further demonstrated the photoconductive nature of HATCNOCn. The proposed strategy could provide a new strategy for the design of novel organic semiconductive materials.

Abstract Excitation‐emission matrix (EEM) has been extensively used as the comprehensive diagnostic tool to extract the biochemical fingerprint of the intrinsic fluorophores in a single scan window. However, there is a gap between the rigorous applications of the statistical tool with respect to discrimination of different stages of the disease which has been the subject for many years. Parallel factor analysis (PARAFAC) is one among the powerful statistical modeling approaches among others. In the present study, a total of 70 EEM matrices of normal, premalignant, and malignant oral tissues were given as a input, and seven intrinsic fluorophores were extracted as “components.” The extracted components were well correlated with respect to the appropriate excitation and emission spectral characteristics of the multiple intrinsic fluorophores such as tryptophan, flavin adenine dinucleotide (FAD), nicotinamide adenine dinucleotide (NADH), collagen‐1, porphyrin, tyrosine, and collagen. Subsequently, the student's t test and linear discriminant analysis (LDA) have been carried out with respect to the fluorescence intensity scores between normal vs. premalignant, normal vs. cancer, and premalignant vs. malignant groups. In normal vs. premalignant, all the seven fluorophores exhibit good statistical accuracy except porphyrin; normal vs. cancer exhibits higher statistical significance for tryptophan, NADH, and FAD than rest of the fluorophores, and premalignant vs. malignant shows proper classification in discriminating FAD, collagen‐1, and collagen. In summary, based on positive predictive value, the normal vs. premalignant exhibits 100% classification than the other two groups. Hence, the PARAFAC analysis could be the alternative and useful diagnostic tool in oral cancer diagnosis.

Within the framework for establishing standards of test methods for superconducting technical wires, various standards have been issued by the International Electrotechnical Commission (IEC) (standard documents IEC 61788-1 to -20). Following the successful round robin test (RRT) for tensile testing REBCO wires at room temperature (Osamura K et al 2014 Supercond. Sci. Technol. 27 085009), this effort is extended to tensile test HTS wires at cryogenic temperatures and is coordinated by the CryoMaK lab at Karlsruhe Institute of Technology. Five different commercially available REBCO wires from five different manufacturers and one BiSCCO wire from another supplier were provided by the Versailles Project on Advanced Materials and Standards (http://vamas.org) for testing. Samples were distributed between eight participating labs from five different countries for testing according to the specified guidelines. After the test results were delivered by all participants, the data were evaluated with statistical tools to investigate the main source of scatter and its magnitude in the test results. The final goal of the RRT is issuing an ISO/IEC standard for a cryogenic temperature tensile test for REBCO wires. In this report the results of the RRT for tensile testing REBCO wires at cryogenic temperatures are presented and discussed.

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In the bridged vacuum gaps, the secondary electron emission avalanche (SEEA) occurring along the surface of solid insulator and the resultant surface charging play a crucial role in the progress of surface discharge. In order to sophisticate the insulation design of high voltage vacuum devices, analysis and control of SEEA charging are of importance. Boersh et al. have proposed a boundary condition on the surface of an insulator to solve the charge distribution at an equilibrium state of SEEA charging. The boundary condition can be easily adopted for analyzing two dimensional SEEA charge distributions. However, the above condition by Boersh et al. cannot be applied in the case of three dimensional distributions. In this paper, the authors newly developed the boundary condition for three dimensional applications and created a numerical simulation code for analyzing three dimensional SEEA charge distributions. Two types of insulator were examined in this study; one was a solid cylinder and the other a hollow cylinder. In the case of the solid cylinder, electric field strength on the cathode was calculated and compared with the measurement. On the other hand, in the case of the hollow cylinder, the calculated result was compared with the charge distribution experimentally obtained by a movable electrostatic probe system. These calculation and measurement results have shown reasonable agreement and we have validated the newly developed numerical simulation method for three dimensional SEEA charge distributions.