A change in the optical polarization associated with a gamma-ray flare in the blazar 3C 279

It is widely accepted that strong and variable radiation detected over all accessible energy bands in a number of active galaxies arises from a relativistic, Doppler-boosted jet pointing close to our line of sight. The size of the emitting zone and the location of this region relative to the central supermassive black hole are, however, poorly known, with estimates ranging from light-hours to a light-year or more. Here we report the coincidence of a gamma-ray flare with a dramatic change of optical polarization angle. This provides evidence for co-spatiality of optical and gamma-ray emission regions and indicates a highly ordered jet magnetic field. The results also require a non-axisymmetric structure of the emission zone, implying a curved trajectory for the emitting material within the jet, with the dissipation region located at a considerable distance from the black hole, at about 10^5 gravitational radii.Comment: Published in Nature issued on 18 February 2010. Corresponding authors: Masaaki Hayashida and Greg Madejsk

Crystalline TiO2 protective layer with graded oxygen defects for efficient and stable silicon-based photocathode

© 2018, The Author(s). The trade-offs between photoelectrode efficiency and stability significantly hinder the practical application of silicon-based photoelectrochemical devices. Here, we report a facile approach to decouple the trade-offs of silicon-based photocathodes by employing crystalline TiO2 with graded oxygen defects as protection layer. The crystalline protection layer provides high-density structure and enhances stability, and at the same time oxygen defects allow the carrier transport with low resistance as required for high efficiency. The silicon-based photocathode with black TiO2 shows a limiting current density of ~35.3 mA cm-2 and durability of over 100 h at 10 mA cm-2 in 1.0 M NaOH electrolyte, while none of photoelectrochemical behavior is observed in crystalline TiO2 protection layer. These findings have significant suggestions for further development of silicon-based, III–V compounds and other photoelectrodes and offer the possibility for achieving highly efficient and durable photoelectrochemical devices

TGA2 signaling in response to reactive electrophile species is not dependent on cysteine modification of TGA2

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Reactive electrophile species (RES), including prostaglandins, phytoprostanes and 12-oxo phytodienoic acid (OPDA), activate detoxification responses in plants and animals. However, the pathways leading to the activation of defense reactions related to abiotic or biotic stress as a function of RES formation, accumulation or treatment are poorly understood in plants. Here, the thiol-modification of proteins, including the RES-activated basic region/leucine zipper transcription factor TGA2, was studied. TGA2 contains a single cysteine residue (Cys186) that was covalently modified by reactive cyclopentenones but not required for induction of detoxification genes in response to OPDA or prostaglandin A1. Activation of the glutathione-S-transferase 6 (GST6) promoter was responsive to cyclopentenones but not to unreactive cyclopentanones, including jasmonic acid suggesting that thiol reactivity of RES is important to activate the TGA2-dependent signaling pathway resulting in GST6 activation We show that RES modify thiols in numerous proteins in vivo, however, thiol reactivity alone appears not to be sufficient for biological activity as demonstrated by the failure of several membrane permeable thiol reactive reagents to activate the GST6 promoter.Peer reviewedFinal Published versio

All-in-one synthesis of mesoporous silicon nanosheets from natural clay and their applicability to hydrogen evolution

Silicon nanosheets have attracted much attention owing to their novel electronic and optical properties and compatibility with existing silicon technology. However, a cost-effective and scalable technique for synthesizing these nanosheets remains elusive. Here, we report a novel strategy for producing silicon nanosheets on a large scale through the simultaneous molten-salt-induced exfoliation and chemical reduction of natural clay. The silicon nanosheets thus synthesized have a high surface area, are ultrathin (similar to 5 nm) and contain mesoporous structures derived from the oxygen vacancies in the clay. These advantages make the nanosheets a highly suitable photocatalyst with an exceptionally high activity for the generation of hydrogen from a water-methanol mixture. Further, when the silicon nanosheets are combined with platinum as a cocatalyst, they exhibit high activity in KOH (15.83 mmol H-2 per s per mol Si) and excellent photocatalytic activity with respect to the evolution of hydrogen from a water-methanol mixture (723 mu mol H-2 per h per g Si).clos

Neutrophils can Promote Clotting via FXI and Impact Clot Structure via Neutrophil Extracellular Traps in a Distinctive Manner in vitro

Neutrophils and neutrophil extracellular traps (NETs) have been shown to be involved in coagulation. However, the interactions between neutrophils or NETs and fibrin(ogen) in clots, and the mechanisms behind these interactions are not yet fully understood. In this in vitro study, the role of neutrophils or NETs on clot structure, formation and dissolution was studied with a combination of confocal microscopy, turbidity and permeation experiments. Factor (F)XII, FXI and FVII-deficient plasmas were used to investigate which factors may be involved in the procoagulant effects. We found both neutrophils and NETs promote clotting in plasma without the addition of other coagulation triggers, but not in purified fibrinogen, indicating that other factors mediate the interaction. The procoagulant effects of neutrophils and NETs were also observed in FXII- and FVII-deficient plasma. In FXI-deficient plasma, only the procoagulant effects of NETs were observed, but not of neutrophils. NETs increased the density of clots, particularly in the vicinity of the NETs, while neutrophils-induced clots were less stable and more porous. In conclusion, NETs accelerate clotting and contribute to the formation of a denser, more lysis resistant clot architecture. Neutrophils, or their released mediators, may induce clotting in a different manner to NETs, mediated by FXI

Water-Vapor-Mediated Close-Spaced Vapor Transport Growth of Epitaxial Gallium Indium Phosphide Films on Gallium Arsenide Substrates

Ga1-xInxP is a technologically important III-V ternary semiconductor widely utilized in commercial and record-efficiency solar cells. We report the growth of Ga1-xInxP by water-vapor-mediated close-spaced vapor transport. Because growth of III-V semiconductors in this system is controlled by diffusion of metal oxide species, we find that congruent transport from the mixed powder source requires complete annealing to form a single alloy phase. Growth from a fully alloyed source at water vapor concentrations of ∼7000 ppm in H2 at 850 °C affords smooth films with electron mobility of 1070 cm2 V-1 s-1 and peak internal quantum efficiency of ∼90% for carrier collection in a nonaqueous photoelectrochemical test cell