Time-domain Brillouin scattering assisted by diffraction gratings

Absorption of ultrashort laser pulses in a metallic grating deposited on a transparent sample launches coherent compression/dilatation acoustic pulses in directions of different orders of acoustic diffraction. Their propagation is detected by the delayed laser pulses, which are also diffracted by the metallic grating, through the measurement of the transient intensity change of the first order diffracted light. The obtained data contain multiple frequency components which are interpreted by considering all possible angles for the Brillouin scattering of light achieved through the multiplexing of the propagation directions of light and coherent sound by the metallic grating. The emitted acoustic field can be equivalently presented as a superposition of the plane inhomogeneous acoustic waves, which constitute an acoustic diffraction grating for the probe light. Thus, the obtained results can also be interpreted as a consequence of probe light diffraction by both metallic and acoustic gratings. The realized scheme of time-domain Brillouin scattering with metallic grating operating in reflection mode provides access to acoustic frequencies from the minimal to the maximal possible in a single experimental configuration for the directions of probe light incidence and scattered light detection. This is achieved by monitoring of the backward and forward Brillouin scattering processes in parallel. Applications include measurements of the acoustic dispersion, simultaneous determination of sound velocity and optical refractive index, and evaluation of the samples with a single direction of possible optical access.Comment: 21 pages, 4 figures, 1 tabl

Preparation of BaTiO3 nanotube arrays, CoFe2O4 nanoparticles and their composite

Multiferroic nanocomposites which possess both ferroelectric and ferromagnetic properties are attracting much attention because of their scientific interest and significant technological promise in the novel multifunctional devices. Gas-phase syntheses have been typically used to fabricate multiferroic nanocomposites [1]; however, high production cost has been hindering further expansion of the research field. In this research, the components of multiferroic nanocomposites are fabricated by anodization and hydrothermal treatment which were then used to fabricate multiferroic nanocomposites through electrophoretic deposition (EPD) as cheaper alternatives to the costly gas-phase processes. TiO2 nanotubes arrays were firstly formed on Ti metal foils by anodization in an electrolyte containing ethylene glycol, dimethyl sulfoxide, ammonium fluoride and water. Then, BaTiO3 nanotube arrays were obtained by hydrothermal treatment of TiO2 nanotube arrays using Ba-containing aqueous solution. The morphologies and crystal structure of BaTiO3 nanotube arrays were analyzed by a scanning electron microscope (SEM) and an X-ray diffractometer (XRD). Please click Additional Files below to see the full abstract

Clock mutation affects circadian regulation of circulating blood cells

BACKGROUND: Although the number of circulating immune cells is subject to high-amplitude circadian rhythms, the underlying mechanisms are not fully understood. METHODS: To determine whether intact CLOCK protein is required for the circadian changes in peripheral blood cells, we examined circulating white (WBC) and red (RBC) blood cells in homozygous Clock mutant mice. RESULTS: Daytime increases in total WBC and lymphocytes were suppressed and slightly phase-delayed along with plasma corticosterone levels in Clock mutant mice. The peak RBC rhythm was significantly reduced and phase-advanced in the Clock mutants. Anatomical examination revealed hemoglobin-rich, swollen red spleens in Clock mutant mice, suggesting RBC accumulation. CONCLUSION: Our results suggest that endogenous clock-regulated circadian corticosterone secretion from the adrenal gland is involved in the effect of a Clock mutation on daily profiles of circulating WBC. However, intact CLOCK seems unnecessary for generating the rhythm of corticosterone secretion in mice. Our results also suggest that CLOCK is involved in discharge of RBC from the spleen

What are differences among Dioxins, Benzopyrenes and indoles in terms of Toxicity through the Aryl hydrocarbon Receptor (AhR) system

Joint Research on Environmental Science and Technology for the Eart

One-Step Synthesis of Gelatin-Conjugated Supramolecular Hydrogels for Dynamic Regulation of Adhesion Contact and Morphology of Myoblasts

Hydrogels possessing fine-adjustable and switchable elasticity emulate the mechanical microenvironments of biological cells, which are known to change dynamically during development and disease progression. In this study, a supramolecular hydrogel conjugated with gelatin side chains was synthesized. By systematically screening the molar fraction of supramolecular host/guest cross-linkers, Young’s modulus of the substrate was fine-adjusted to the level for myoblasts, E ≈ 10 kPa. C₂C₁₂ myoblasts reproducibly and firmly adhered to the gelatin-conjugated hydrogel via focal adhesion contacts consisting of integrin clusters, whereas only a few cells adhered to the gel without gelatin side chains. The elasticity of the gelatin-conjugated hydrogel was switchable to desired levels by simply adding and removing free guest molecules in appropriate concentrations without interfering with cell viability. Immunofluorescence confocal microscopy images of fixed cells confirmed the adaptation of focal adhesions and remodeling of actin cytoskeletons on the gelatin-conjugated hydrogel. Time-lapse phase-contrast images demonstrated the dynamic response of the cells, manifested in their morphology, to an abrupt change in the substrate elasticity. Gelatin-conjugated hydrogels with switchable elasticity enable the direct and reversible mechanical stimulation of cells in one step without tedious surface functionalization with adhesion ligands