Bioinspired Flexible and Tough Layered Peptide Crystals

One major challenge of functional material fabrication is combining flexibility, strength, and toughness. In several biological and artificial systems, these desired mechanical properties are achieved by hierarchical architectures and various forms of anisotropy, as found in bones and nacre. Here, it is reported that crystals of N‐capped diphenylalanine, one of the most studied self‐assembling systems in nanotechnology, exhibit well‐ordered packing and diffraction of sub‐Å resolution, yet display an exceptionally flexible nature. To explore this flexibility, the mechanical properties of individual crystals are evaluated, assisted by density functional theory calculations. High‐resolution scanning electron microscopy reveals that the crystals are composed of layered self‐assembled structures. The observed combination of strength, toughness, and flexibility can therefore be explained in terms of weak interactions between rigid layers. These crystals represent a novel class of self‐assembled layered materials, which can be utilized for various technological applications, where a combination of usually contradictory mechanical properties is desired.     

Inorganic Halide Perovskitoid TlPbI3 for Ionizing Radiation Detection

Room temperature semiconductor detector (RTSD) materials for γ-ray and X-ray radiation are in great demand for the nonproliferation of nuclear materials as well as for biomedical imaging applications. Halide perovskites have attracted great attention as emerging and promising RTSD materials. In this contribution, the material synthesis, purification, crystal growth, crystal structure, photoluminescence properties, ionizing radiation detection performance, and electronic structure of the inorganic halide perovskitoid compound TlPbI₃ are reported on. This compound crystallizes in the ABX₃ non-perovskite crystal structure with a high density of d = 6.488 g·cm^–3, has a wide bandgap of 2.25 eV, and melts congruently at a low temperature of 360 °C without phase transitions, which allows for facile growth of high quality crystals with few thermally-activated defects. High-quality TlPbI₃ single crystals of centimeter-size are grown using the vertical Bridgman method using purified raw materials. A high electrical resistivity of ≈10¹² Ω·cm is readily obtainable, and detectors made of TlPbI₃ single crystals are highly photoresponsive to Ag K_α X-rays (22.4 keV), and detects 122 keV γ-rays from ⁵⁷Co radiation source. The electron mobility-lifetime product µ_eτ_e was estimated at 1.8 × 10^–5 cm²·V^–1. A high relative static dielectric constant of 35.0 indicates strong capability in screening carrier scattering and charged defects in TlPbI₃.     

Effects of high relative humidity on the dynamic adsorption of dimethyl methylphosphonate (DMMP) on activated carbon

The effects of high relative humidity (RH) on the breakthrough of the nerve agent simulant dimethyl methylphosphonate (DMMP) vapor in beds of ASC-impregnated, activated carbon were investigated. Maximum concentrations of DMMP at room temperature and RH > 60% were found to be lower by more than an order of magnitude than in dry air. The breakthrough time (t_B) of 1.2 × 10⁻⁴ g l⁻¹ DMMP in pre-humidified beds and humid air of RH = 90% was shortened by a factor of 1.6 relative to adsorption in dry beds and dry air. Analysis of the breakthrough curves according to the Wheeler–Jonas model indicated that the high RH lowered the dynamic adsorption capacity (W_E) but had nearly no effect on the critical bed weight (W_C). The reduction of W_E by humidity correlates with the observed displacement of adsorbed water by DMMP. The use of DMMP for testing filter performance is limited to low and intermediate relative humidities. On the other hand, DMMP in dry air can be used to advantage for testing the capacity of new or used respirator filters and for the detection of filter channeling.     

Characterization of almond alpha-mannosidase and its application for structure analysis of sugar chain

Almond alpha-mannosidase was purified by separation on columns of DEAE-Sephadex A50 and hydroxyapatite, and characterized. Its optimum pH was approximately 3.8. It was also shown to be stable from pH 6 to 8. Its activity was stable up to 60 degrees C. The thermostability of almond alpha-mannosidase at 73 degrees C appeared to be superior to that of jack bean a-mannosidase. We examined the substrate specificity of the former toward high-mannose-type N-glycan Man9GlcNAc2, and showed that the deduced trimming pathway was more diverse than that of the latter. We could use almond alpha-mannosidase as well as jack bean alpha-mannosidase for analysis of sugar chain structures.     

Influence of chemotherapy on FDG uptake by human cancer xenografts in nude mice

This study evaluated the use of PET with 18F-2-deoxy-2-fluoro-D-glucose (18F-FDG) for monitoring chemotherapy effects, using a human cancer xenograft (poorly differentiated human gastric cancer) in vivo model. METHODS: Tumor 18F-FDG uptakes and sizes were measured after administrating mitomycin (MMC), cisplatin (CDDP) and adriamycin (ADR) to xenograft-bearing nude mice and compared with 18F-FDG tumor uptake and tumor size in a non-therapy group. The correlation between the uptake and size was also assessed. RESULTS: The largest reduction in tumor size after chemotherapy occurred in the MMC administered group, followed by the CDDP case, with no reduction in the ADR group as compared to the controls. Fluorine-18-FDG tumor uptake after chemotherapy was also decreased in the MMC and CDDP groups, in that order, but not in the ADR case. With MMC and CDDP, size reduction became significant on Days 8 or 11, whereas 18F-FDG tumor uptake had already been decreased on Days 3 or 7. CONCLUSION: Fluorine-18-FDG uptake decreases in parallel to the efficacy of anticancer agents and correlates with subsequent morphologic changes. We conclude that 18F-FDG PET tumor images are indeed useful for monitoring the effects of cancer chemotherapy.     

The paradox of group-based guilt: Modes of national identification, conflict vehemence, and reactions to the in-group's moral violations.

The authors examined the relationships between 2 modes of national identification (attachment to the in-group and the in-group's glorification) and reactions to the in-group's moral violations among Israeli students. Data were collected during a period of relative calm in the Israeli-Palestinian conflict as well as during a period of great intensification of this conflict. As expected, in Study 1, the 2 modes of identification had contrasting relationships with group-based guilt: Attachment was positively related whereas glorification was negatively related to group-based guilt for in-group's past infractions. Glorification suppressed the attachment effect but not vice versa. Both relationships were mediated by the use of exonerating cognitions. In Study 2, group-based guilt for the in-group's current wrongdoings was increased by priming critical rather than conventional attachment to the in-group, suggesting a causal effect of mode of identification on the experience of negative group-based emotions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optical Lattice Clock

Latest progress in optical atomic clocks is so rapid that serious discussions toward the redefinition of the second is initiated. Besides single ion clocks developed since early 1980s, optical lattice clocks just invented a decade ago are one of strong candidates as a method to realize the revised definition. The current situation of this emerging method of optical clocks is briefly described.     

Wind turbine aerodynamics using ALE–VMS: validation and the role of weakly enforced boundary conditions

In this article we present a validation study involving the full-scale NREL Phase VI two-bladed wind turbine rotor. The ALE–VMS formulation of aerodynamics, based on the Navier–Stokes equations of incompressible flows, is employed in conjunction with weakly enforced essential boundary conditions. We find that the ALE–VMS formulation using linear tetrahedral finite elements is able to reproduce experimental data for the aerodynamic (low-speed shaft) torque and cross-section pressure distribution of the NREL Phase VI rotor. We also find that weak enforcement of essential boundary conditions is critical for obtaining accurate aerodynamics results on relatively coarse boundary layer meshes. The proposed numerical formulation is also successfully applied to the aerodynamics simulation of the NREL 5MW offshore baseline wind turbine rotor.     

High-performance computing of wind turbine aerodynamics using isogeometric analysis

In this article we present a high-performance computing framework for advanced flow simulation and its application to wind energy based on the residual-based variational multiscale (RBVMS) method and isogeometric analysis. The RBVMS formulation and its suitability and accuracy for turbulent flow in a moving domain are presented. Particular emphasis is placed on the parallel implementation of the methodology and its scalability. Two challenging flow cases were considered: the turbulent Taylor–Couette flow and the NREL 5 MW offshore baseline wind turbine rotor at full scale. In both cases, flow quantities of interest from the simulation results compare favorably with the reference data and near-perfect linear parallel scaling is achieved.