Transient optical processes in YAP crystals induced by UV light pulses

1999 ◽  
Author(s):  
Dmitry Y. Sugak ◽  
A. N. Durygin ◽  
Andrej O. Matkovskii ◽  
Andrzej Suchocki ◽  
D. Savitskii ◽  
...  
Keyword(s):  
Uv Light ◽  
Light Pulses

Practical photomask pinhole defect repair using micrometer scale pattern Cd CVD with kHz repetition UV light pulses

1985 ◽  
Author(s):  
Y. MORISHIGE ◽  
H. YOKOYAMA ◽  
S. KISHIDA ◽  
K. WASHIO ◽  
H. KINOSHITA ◽  
...  
Keyword(s):  
Uv Light ◽  
Light Pulses ◽  
Defect Repair ◽  
Micrometer Scale

scholarly journals Преобразования радиационно-наведенных молекулярных точечных дефектов и центров окраски в кристаллах LiF под воздействием света

2019 ◽  
Vol 61 (10) ◽  
pp. 1852
Author(s):  
Л.И. Брюквина
Keyword(s):  
Hydrogen Bond ◽  
Optical Absorption ◽  
Ir Spectra ◽  
Exposure Time ◽  
Uv Light ◽  
Molecular Complexes ◽  
Strong Hydrogen Bond ◽  
Color Centers ◽  
Weak Hydrogen Bond ◽  
Light Pulses

The effect of UV light and light pulses of the integral light of lamps on γ-irradiated LiF crystals with impurities of hydroxyl ions and magnesium were investigated. The optical absorption and luminescence of color centers at different stages bleaching depending on the exposure time of the crystal under UV light or from the number of light pulses were studied. IR spectra of molecular complexes with hydrogen bond and hydroxyl ions at different stages of bleaching are present. The transformation of complexes with a strong hydrogen bond in complexes with a weak hydrogen bond, and vice versa under the action of light are shown. It is presented as molecular complexes with hydrogen bond affect transformations color centers in the process of crystal bleaching.

scholarly journals Low-Power Graphene/ZnO Schottky UV Photodiodes with Enhanced Lateral Schottky Barrier Homogeneity

Nanomaterials ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 799 ◽  
Author(s):  
Youngmin Lee ◽  
Deuk Young Kim ◽  
Sejoon Lee
Keyword(s):  
Thermal Treatment ◽  
Low Power ◽  
Schottky Barrier ◽  
High Performance ◽  
Uv Light ◽  
Optical Power ◽  
Graphene Surface ◽  
Light Pulses ◽  
Uv Illumination ◽  
Optical Power Density

The low-power, high-performance graphene/ZnO Schottky photodiodes were demonstrated through the direct sputter-growth of ZnO onto the thermally-cleaned graphene/SiO2/Si substrate at room temperature. Prior to the growth of ZnO, a thermal treatment of the graphene surface was performed at 280 °C for 10 min in a vacuum to desorb chemical residues that may serve as trap sites at the interface between graphene and ZnO. The device clearly showed a rectifying behavior with the Schottky barrier of ≈0.61 eV and an ideality factor of 1.16. Under UV illumination, the device exhibited the excellent photoresponse characteristics in both forward and reverse bias regions. When illuminating UV light with the optical power density of 0.62 mW/cm2, the device revealed a high on/off current ratio of >103 even at a low bias voltage of 0.1 V. For the transient characteristics upon switching of UV light pulses, the device represented a fast and stable photoresponse (i.e., rise time: 0.16 s, decay time: 0.19 s). From the temperature-dependent current–voltage characteristics, such an outstanding photoresponse characteristic was found to arise from the enhanced Schottky barrier homogeneity via the thermal treatment of the graphene surface. The results suggest that the ZnO/graphene Schottky diode holds promise for the application in high-performance low-power UV photodetectors.

Versatile and High-Repetition Subnanosecond Light Source for Fluorescence Lifetime Measurements

1992 ◽  
Vol 46 (3) ◽  
pp. 458-463 ◽  
Author(s):  
Tsutomu Araki ◽  
Nobuhiro Hanabusa ◽  
Teruo Uchida ◽  
Xue F. Wang ◽  
Shigeo Minami
Keyword(s):  
Light Source ◽  
Atmospheric Pressure ◽  
Uv Light ◽  
Nanosecond Duration ◽  
High Repetition ◽  
Light Pulses ◽  
Pulsed Uv Light ◽  
Discharge Gap ◽  
Bromide Solutions ◽  
Air Discharge

We describe the construction and emission characteristics of a gap-adjustable, capacitor-replaceable pulsed light source (air-discharge type) that produces high-repetition pulsed UV light of nanosecond duration. Stable light pulses of 0.8 to 3.5 ns width are generated from atmospheric-pressure air discharge between the sharp anode and round cathode. Appreciable heterogeneities on the distribution of emission intensity and its on-set timing along the discharge gap were observed. Fluorescence lifetimes of ethidium bromide solutions were measured to demonstrate the usefulness of the light source.

Electron microscopy of keratinocytes cultured on a collagen substrate used as an allograft for the treatment of chronic wounds

1992 ◽  
Vol 50 (2) ◽  
pp. 1104-1105
Author(s):  
Debby A. Jennings ◽  
Michael J. Morykwas ◽  
Louis C. Argenta
Keyword(s):  
Electron Microscopy ◽  
Cell Suspension ◽  
Single Cell ◽  
Chronic Wounds ◽  
Mechanical Stability ◽  
Uv Light ◽  
Type I ◽  
Single Cell Suspension ◽  
Collagen Substrate ◽  
Dermal Collagen

Grafts of cultured allogenic or autogenic keratlnocytes have proven to be an effective treatment of chronic wounds and burns. This study utilized a collagen substrate for keratinocyte and fibroblast attachment. The substrate provided mechanical stability and augmented graft manipulation onto the wound bed. Graft integrity was confirmed by light and transmission electron microscopy.Bovine Type I dermal collagen sheets (100 μm thick) were crosslinked with 254 nm UV light (13.5 Joules/cm2) to improve mechanical properties and reduce degradation. A single cell suspension of third passage neonatal foreskin fibroblasts were plated onto the collagen. Five days later, a single cell suspension of first passage neonatal foreskin keratinocytes were plated on the opposite side of the collagen. The grafts were cultured for one month.The grafts were fixed in phosphate buffered 4% formaldehyde/1% glutaraldehyde for 24 hours. Graft pieces were then washed in 0.13 M phosphate buffer, post-fixed in 1% osmium tetroxide, dehydrated, and embedded in Polybed 812.

A photoelectron microscope study of surfaces

1989 ◽  
Vol 47 ◽  
pp. 10-11
Author(s):  
W. Engel ◽  
M. Kordesch ◽  
A. M. Bradshaw ◽  
E. Zeitler
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Field Strength ◽  
Uv Light ◽  
Physical Property ◽  
Photon Flux ◽  
Mercury Lamp ◽  
Object Surface ◽  
The Sixties ◽  
Physical Features

Photoelectron microscopy is as old as electron microscopy itself. Electrons liberated from the object surface by photons are utilized to form an image that is a map of the object's emissivity. This physical property is a function of many parameters, some depending on the physical features of the objects and others on the conditions of the instrument rendering the image.The electron-optical situation is tricky, since the lateral resolution increases with the electric field strength at the object's surface. This, in turn, leads to small distances between the electrodes, restricting the photon flux that should be high for the sake of resolution.The electron-optical development came to fruition in the sixties. Figure 1a shows a typical photoelectron image of a polycrystalline tantalum sample irradiated by the UV light of a high-pressure mercury lamp.

Immunolabelling of glomerular deposits in kidney biopsies routinely fixed in glutaraldehyde

1989 ◽  
Vol 47 ◽  
pp. 910-911
Author(s):  
Ś Lhoták ◽  
I. Alexopoulou ◽  
G. T. Simon
Keyword(s):  
Uv Light ◽  
Kidney Diseases ◽  
Light Chains ◽  
Microscopical Level ◽  
Accurate Identification ◽  
Light Microscopical Level ◽  
Dense Deposits ◽  
Cacodylate Buffer ◽  
Glomerular Deposits ◽  
Prognostic Importance

Various kidney diseases are characterized by the presence of dense deposits in the glomeruli. The type(s) of immunoglobulins (Igs) present in the dense deposits are characteristic of the disease. The accurate Identification of the deposits is therefore of utmost diagnostic and prognostic importance. Immunofluorescence (IF) used routinely at the light microscopical level is unable to detect and characterize small deposits found in early stages of glomerulonephritis. Although conventional TEM is able to localize such deposits, it is not capable of determining their nature. It was therefore attempted to immunolabel at EM level IgG, IgA IgM, C3, fibrinogen and kappa and lambda Ig light chains commonly found in glomerular deposits on routinely fixed ( 2% glutaraldehyde (GA) in 0.1M cacodylate buffer) kidney biopsies.The unosmicated tissue was embedded in LR White resin polymerized by UV light at -10°C. A postembedding immunogold technique was employed

Sorbitol enhances the physicochemical stability of B12 vitamers

2020 ◽  
Vol 90 (5-6) ◽  
pp. 439-447 ◽  
Author(s):  
Andrew Hadinata Lie ◽  
Maria V Chandra-Hioe ◽  
Jayashree Arcot
Keyword(s):  
Ascorbic Acid ◽  
Uv Light ◽  
Heat Exposure ◽  
Water Soluble ◽  
Uv Exposure ◽  
Physicochemical Stability ◽  
Before And After ◽  
The Stability

Abstract. The stability of B12 vitamers is affected by interaction with other water-soluble vitamins, UV light, heat, and pH. This study compared the degradation losses in cyanocobalamin, hydroxocobalamin and methylcobalamin due to the physicochemical exposure before and after the addition of sorbitol. The degradation losses of cyanocobalamin in the presence of increasing concentrations of thiamin and niacin ranged between 6%-13% and added sorbitol significantly prevented the loss of cyanocobalamin (p<0.05). Hydroxocobalamin and methylcobalamin exhibited degradation losses ranging from 24%–26% and 48%–76%, respectively; added sorbitol significantly minimised the loss to 10% and 20%, respectively (p < 0.05). Methylcobalamin was the most susceptible to degradation when co-existing with ascorbic acid, followed by hydroxocobalamin and cyanocobalamin. The presence of ascorbic acid caused the greatest degradation loss in methylcobalamin (70%-76%), which was minimised to 16% with added sorbitol (p < 0.05). Heat exposure (100 °C, 60 minutes) caused a greater loss of cyanocobalamin (38%) than UV exposure (4%). However, degradation losses in hydroxocobalamin and methylcobalamin due to UV and heat exposures were comparable (>30%). At pH 3, methylcobalamin was the most unstable showing 79% degradation loss, which was down to 12% after sorbitol was added (p < 0.05). The losses of cyanocobalamin at pH 3 and pH 9 (~15%) were prevented by adding sorbitol. Addition of sorbitol to hydroxocobalamin at pH 3 and pH 9 reduced the loss by only 6%. The results showed that cyanocobalamin was the most stable, followed by hydroxocobalamin and methylcobalamin. Added sorbitol was sufficient to significantly enhance the stability of cobalamins against degradative agents and conditions.

Sign in / Sign up

Export Citation Format

Share Document