41 research outputs found
Transverse emittance measurements on an S-band photoinjector rf electron gun
Proposed fourth generation light sources using SASE FELs to generate short
pulse, coherent, X-rays require demonstration of high brightness electron
sources. The Gun Test Facility (GTF) at SLAC was built to test high brightness
sources for the proposed Linac Coherent Light Source at SLAC. The transverse
emittance measurements are made at nearly 30 MeV by measuring the spot size on
a YAG screen using the quadrupole scan technique. The emittance was measured to
vary from 1 to 3.5 mm-mrad as the charge is increased from 50 to 350 pC using a
laser pulse width of 2 ps FWHM. The measurements are in good agreement with
simulation results using the LANL version of PARMELA.Comment: 12 pages, 4 figures, contributed to The 23rd Int. FEL Conf.,
Darmstadt, 20-24 Aug. 200
Superhard Phases of Simple Substances and Binary Compounds of the B-C-N-O System: from Diamond to the Latest Results (a Review)
The basic known and hypothetic one- and two-element phases of the B-C-N-O
system (both superhard phases having diamond and boron structures and
precursors to synthesize them) are described. The attention has been given to
the structure, basic mechanical properties, and methods to identify and
characterize the materials. For some phases that have been recently described
in the literature the synthesis conditions at high pressures and temperatures
are indicated.Comment: Review on superhard B-C-N-O phase
Experimental study and critical review of structural, thermodynamic and mechanical properties of superhard refractory boron suboxide, B6O
In the present paper we performed the analysis of available data on
structural, thermodynamic and mechanical properties of B6O. Although the
compound is known for half a century and has been extensively studied, many
properties of this boron-rich solid remain unknown or doubtful. Semi-empirical
analysis of our experimental and literature data allowed us to choose the best
values of main thermodynamic and mechanical characteristics among previously
reported data, to predict the thermoelastic equation of state of B6O, and
dependence of its hardness on non-stoichiometry and temperature
Assessment of the genotoxic and mutagenic properties of Himatanthus articulatus bark extracts used as phytotherapeutic drug in the Amazon
AbstractEthnopharmacological relevanceHimatanthus articulatus (Apocynaceae) is a plant native to the Amazon, popularly used to treat external ulcers, tumors, inflammations, cancer, syphilis and malaria.Aim of the studyTo investigate the in vivo genotoxic and mutagenic potential of this plant, using the comet assay and the micronucleus test.Material and methodsFemale and male adult mice were treated with 500mg/kg, 1000mg/kg or 2000mg/kg of Himatanthus articulatus aqueous or ethanolic bark extracts by gavage for two consecutive days. In addition, blood slides were exposed to hydrogen peroxide (ex vivo) to evaluate the anticlastogenic effect using the comet assay. The HPLC analyses indicated plumieride as the main constituent of both extracts from Himatanthus articulatus barks.ResultsNo differences between genders were observed. Micronuclei were observed only in the group treated with the highest dose of both extracts. Conversely, lower doses of these extracts showed protective effects to DNA against damage induced by hydrogen peroxide, indicating an important antigenotoxic effect.ConclusionsThe toxicological evaluation indicated that the extracts are non-genotoxic and reduce the clastogenic damage induced by hydrogen peroxide. In part, this result can be atributted to the phytochemical profile of Himatanthus articulatus, which presents iridoids and phenolic compounds