Phototoxicity of visible light laser on the porphyrin-producing bacteria, Porphyromonas gingivalis, in the absence of photosensitizers and under aerobic conditions was shown in previous studies. Recently, we found that the noncoherent visible light sources at wavelengths of 400-500 nm, commonly used in restorative dentistry, induced a phototoxic effect on P. gingivalis, as well as on Fusobacterium nucleatum, and to a lesser extent on the Streptococci sp. To elucidate the mechanism of this phototoxic effect, P. gingivalis and F. nucleatum were exposed to light (1) under aerobic and anaerobic environments and (2) in the presence of scavengers of reactive oxygen species (ROS). Phototoxic effect was not observed when the bacteria were exposed to light under anaerobic conditions. Dimethyl thiourea, a hydroxyl radical scavenger, was effective in reducing phototoxicity (P
Polotsky, Hans Jacob (1905–91) Israeli professor of Egyptian and Semitic linguistics. Born to Russian parents in Zurich, Polotsky attended the universities of Göttingen and Berlin, where he studied Egyptology and [...]
Nanoparticle-polymer composites are diverse and versatile functional materials, with applications ranging from electronic device fabrication to catalysis. This review focuses on the use of chemical design to control the structural attributes of polymer-mediated assembly of nanoparticles. We will illustrate the use of designed particles and polymers to create nanocomposites featuring interesting and pragmatic structures and properties. We will also describe applications of these engineered materials.
In this work we report on culturing of Aplysia neurons and vertebrate cells to porous silicon substrates and on the first steps toward characterizing porous silicon as a biosensor of neural activity. Neurons cultured on porous silicon substrates survived for at least one week showing normal passive membrane properties and generation of action potentials. We have investigated several mechanisms that take advantage of the optical properties of porous silicon for transducing both electrical and chemical neuronal activities into photonic signals. For example, the photoluminescence response to voltage and the reflectivity response to chemical changes were investigated.
PADMA 28, a multi-component herbal mixture formulated according to an ancient Tibetan recipe, was assessed for effects on human dermal fibroblasts and epidermal keratinocytes in monolayer culture, and for effects on human skin in organ culture. PADMA 28 stimulated survival of fibroblasts in monolayer culture. In fibroblast monolayer culture and human skin organ culture, levels of matrix metalloproteinase-1 (MMP-1; interstitial collagenase) were reduced and type I procollagen production was increased. When keratinocytes were examined, there was no evidence of growth stimulation over a wide range of PADMA 28 concentrations. At high concentration, PADMA 28 inhibited keratinocyte proliferation. When organ cultures of human skin were treated with PADMA 28, there was no evidence of hyperplastic growth in the epidermis. Topical treatment of rhino mice with PADMA 28 failed to induce epidermal hyperplasia and was completely non-irritating. The ability to stimulate collagen production and inhibit the major collagen-degrading enzyme in skin without inducing a hyperplastic response in the epidermis may provide a basis for development of the herbal preparation as a "skin-repair" agent.
Electronic structure calculations predict the existence of a novel type of a chemically bound noble gas compound. The predicted species is an extended linear and periodic polymer, made of the repeat unit -(XeCC)-, where CC is the acetylenic group. The polymer has a strong partly ionic nature, with positive partial charge on the xenon atoms and a negative one on the CC groups. High energy barriers are found for the removal of a Xe atom from the chain, indicating high stability. This is the first polymer with a noble-gas-containing building block. 2005 American Institute of Physics.
The prodn. of nanoparticles from oil-in-water nanoemulsions, occurs by phase inversion techniques. The phase inversion may be achieved by using a const. temp., where the inversion occurs by continuous addn. of H2O or by varying the temp. involving heating and rapid cooling. More specifically, the process comprises (a) mixing the active agent (e.g. monomer) with a volatile solvent and ≥1 nonionic surfactant, (b) adding to the mixt. of (a) an aq. phase to form a water-in-oil emulsion, (c) continuously adding to the emulsion of (b) water at a rate enabling phase inversion and formation of oil-in-water nanoemulsion, (d) evapg. the volatile solvent from the oil-in-water nanoemulsion of (c) to obtain nanoparticles. The formation of lauryl acrylate polymer nanoparticles was demonstrated in the presence of Brij 96v. [on SciFinder(R)]
A slab waveguide was fabricated in a potassium lithium tantalate niobate crystal by the implantation of He2+ ions at 2.26 MeV. The waveguide profile and loss were evaluated by measuring the dark mode TE spectrum using the prism coupling method at λ=1.3 μm. The implantation generated amorphous cladding layer 5 μm below the surface of the crystal with a refractive index lower by 3.9% then that of the substrate. The propagation loss of the waveguided modes was found to be 0.1–0.2 dB/cm. Thermal stability of the waveguide was obtained by isothermal annealing at 351 and 446 °C. Following the annealing the waveguide index profile remained unchanged when subjected to annealing at 150 °C for one week. [ABSTRACT FROM AUTHOR]Copyright of Applied Physics Letters is the property of American Institute of Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
The design and performance of several generations of wavelength-selective 1 X K switches are reviewed. These optical subsystems combine the functionality of a demultiplexer, per-wavelength switch, and multiplexer in a single, low-loss unit. Free-space optics is utilized for spatially separating the constituent wavelength division multiplexing (WDM) channels as well as for space-division switching from an input optical fiber to one of K output fibers (1 X K functionality) on a channel-by-channel basis using a microelectromechanical system (MEMS) micromirror array. The switches are designed to provide wide and flat pass- bands for minimal signal distortion. They can also provide spectral equalization and channel blocking functionality, making them well suited for use in transparent WDM optical mesh networks.
A spatial rainfall model was applied to radar data of air mass thunderstorms to yield a rainstorm representation as a set of convective rain cells. The modeled rainfall was used as input into hydrological model, instead of the standard radar-grid data. This approach allows a comprehensive linkage between runoff responses and rainfall structures
A spatial rainfall model was applied to radar data of air mass thunderstorms to yield a rainstorm representation as a set of convective rain cells. The modeled rainfall was used as input into hydrological model, instead of the standard radar-grid data. This approach allows a comprehensive linkage between runoff responses and rainfall structures
Interviews Yosef Hayim Yerushalmi, a Columbia University historian specializing in medieval and modern Jewish history, discussing his life and scholarly career.
