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1.
PurposeTo determine the field output correction factors of the radiophotoluminescence glass dosimeter (RPLGD) in parallel and perpendicular orientations with reference to CC01, the ionization chamber.MethodsThe dose to a small water volume and the sensitive volume of the RPLGD and the IBA-CC01 were determined for 6-MV, 100-cm SAD, 10-cm depth using egs_chamber user-code. The RPLGD in perpendicular and parallel orientations to the beam axis were studied. The field output correction factors of each detector for 0.5 × 0.5 to 10 × 10 cm2 field sizes were determined. These field output correction factors were validated by comparing field output factors against data determined from IAEA-AAPM TRS-483 code of practice.ResultsThe field output correction factors of all detectors were within 5% for field sizes down to 0.8 × 0.8 cm2. For 0.5 × 0.5 cm2, the field output correction factors of CC01, RPLGD in perpendicular and parallel orientations differed from unity by 14%, 19%, and 5%, respectively. The percentage difference between field output factors determined using RPLGD and CC01 data, corrected using the field output correction factors determined in this work and measurements with CC01 data corrected using TRS-483, was less than 3% for all field sizes, except for the smallest field size of RPLGD in perpendicular orientation and the CC01.ConclusionsThe field output correction factors of RPLGD and CC01 are reported. The validation proves that RPLGD in parallel orientation combined with the field output correction factors is the most suitable for determining the field output factors for the smallest field used in this study. 相似文献
2.
Karthish Manthiram Brandon J. Beberwyck Dmitri V. Talapin A. Paul Alivisatos 《Journal of visualized experiments : JoVE》2013,(82)
We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded synthesis strategy is used in which spherical seeds of CdSe are prepared first using a hot-injection technique. By controlling the crystal structure of the seed to be either wurtzite or zinc-blende, the subsequent hot-injection growth of CdS off of the seed results in either a rod-shaped or tetrapod-shaped nanocrystal, respectively. The phase and morphology of the synthesized nanocrystals are confirmed using X-ray diffraction and transmission electron microscopy, demonstrating that the nanocrystals are phase-pure and have a consistent morphology. The extinction coefficient and quantum yield of the synthesized nanocrystals are calculated using UV-Vis absorption spectroscopy and photoluminescence spectroscopy. The rods and tetrapods exhibit extinction coefficients and quantum yields that are higher than that of the bare seeds. This synthesis demonstrates the precise arrangement of materials that can be achieved at the nanoscale by using a seeded synthetic approach. 相似文献
3.
4.
Neuraminidase in Calf Retinal Outer Segment Membranes 总被引:1,自引:1,他引:0
Abstract: An enzyme catalyzing the hydrolysis of sialic acid ( N -acetylneuraminic acid: NeuNAc)-containing glycoconjugates has been found in bovine retinal rod outer segment (ROS) membranes. The enzymatic activity is optimal at pH 4.0 and is stimulated by 0.15% Triton X-100. Total activity was determined by the release of NeuNAc from endogenous and exogenous substrates (GDla). The ROS enzyme preferentially hydrolyses the ROS gangliosides, possibly because they are more accessible than the glycoproteins as substrates for the neuraminidase. Release of NeuNAc from gangliosides leads to important changes in the ganglioside patterns; whereas the amounts of GM1 increased throughout the incubation, the levels of polysialogangliosides GTlb and GD3 diminished owing to their rapid hydrolysis. The finding that gangliosides are hydrolysed more extensively than glycoproteins suggests that endogenous ROS gangliosides may be the principal source of metabolically available sialic acid in ROS. It was also observed that the activity of ROS neuraminidase is not affected by illumination of the membranes. 相似文献
5.
Kristel Eggermont Inge J. Goderis Willem F. Broekaert 《Plant Molecular Biology Reporter》1996,14(3):273-279
We describe here a reliable high-throughput method for extraction of RNA from fresh or frozen plant tissue that obviates laborious
and time-consuming homogenisation by mortar and pestle. The method is based on homogenisation by high-speed reciprocal shaking
in presence of a mixture of inexpensive abrasive materials; i.e., quartz sand and glass beads. After homogenisation, the method
follows a standard procedure for RNA extraction by phenol/LiCl. Yield and quality of RNA obtained by homogenisation with the
sand/glass bead mix are identical to those obtained by mortar and pestle. 相似文献
6.
A thorough analysis of glass containing Eu2O3 and Dy2O3, or Eu2O3, Dy2O3, and CuO melted together with nanodiamond powder was pursued based on measurements of optical absorption, photoluminescence (PL) emission and excitation spectra, and colorimetry. Nanodiamond facilitated the stabilization of Cu+ and Eu2+ ions with blue-emitting characteristics that, along with yellow-emitting Dy3+ and red-emitting Eu3+ led to the white light-emitting glass. Novel intensity notations implemented in intensity-based spectral ratios, and difference intensity correlation analysis were proposed for the assessment of PL properties. The chromaticity and correlated colour temperature of the emission were ultimately investigated as a two-parametric problem based on: (1) the different ionic components; and (2) the various excitation wavelengths employed. The optical analysis approach adds to the characterization methods to further fundamental understanding and provide helpful analytical tools for designing materials for tunable white light-emitting devices. 相似文献
7.
Stanley S. Stadnicki Franklin R. Leach 《In vitro cellular & developmental biology. Plant》1978,14(7):601-605
Summary HeLa and L-M cells can be effectively grown directly on glass fiber filters to yield replicate cultures that allow easy analysis
of biosynthetic capabilities through measurement of radioactive precursor uptake and incorporation. The glass fiber filters
are superior to glass cover slips, growth in scintillation vials, and growth on Millipore filters in the ease of handling
during experimental treatment and in the amount of radioactivity incorporated during the labeling period. These parameters
are experimentally established and a typical application of the procedure that demonstrates the hydroxyurea inhibition of
DNA synthesis is presented.
This research was supported by Oklahoma Agricultural Experiment Station Project 1534. This publication is Article J-3334 of
the Oklahoma Agricultural Experimental Station. 相似文献
8.
Cyclic GMP concentration was measured in the rod outer segments (ROS) of the isolated frog retinas. Retinas were quickly frozen in 0.5 s after the short light flash producing 90%-saturated late receptor potential (2,000 rhodopsins bleached per rod). ROS were obtained by microdissection, and cGMP levels were determined by radioimmunoassay method. No detectable changes in cGMP concentration was found in this stimulus condition. Dark-adapted ROS contained 46.3 ± 1.5 pmole cGMP per mg dry weight, flash-illuminated ones –45 ± 2 pmole/mg. 3-s bright illumination (ca. 107 rhodopsins bleached per rod per second) led to approximately 30% drop in cGMP content. It is supposed that the main part of cGMP within the ROS is in the bound state and therefore fast light-induced changes in its minor free fraction may escape the detection. 相似文献
9.
A highly active inhibitor of the binding of estrone and estradiol-17β to rat alpha-fetoprotein is demonstrated for the first time in embryo, immature and adult rat sera as well as in fetal and adult human sera. The competitive character and the narrow specificity of this inhibition effect is shown. The major compound responsible for this activity is isolated by successive column Sephadex LH20 and thin layer chromatography : it is characterized as a nonpolar, nonphenolic, dialysable and thermostable substance, unreactive towards anti-estrone and anti-estradiol-17β anti-bodies. The possible biological role of an endogenous non-estrogen ligand of rodent fetoproteins is discussed. 相似文献
10.
The total and active immobilized enzyme (IME) distributions in porous supports are studied both theoretically and experimentally. In order to determine experimentally the enzyme distribution profiles within a single particle, we construct a diffusion cell containing controlled-pore glass particles such that the cell would mimic a large pellet support. Our purpose is to study the interplay between the diffusion process within the interparticle void space and immobilization process in the controlled-pore glass particles onto the evolution of the (total and active) enzyme distributions. A mathematical model is developed to describe the interaction of various processes within the diffusion cell. The immobilized enzymes are determined for a system of trypsin and controlled-pore glass particles. The total amount of enzymes are determined by the amino acid analysis, and the active fraction is obtained by an active-site titration. The experimentally measured total IME profiles compare very well with that predicted by the model. The determined active enzyme profile is found to be nonuniform one, and it represents about 40% of the total enzyme immobilized in the support particles. 相似文献