نتایج جستجو برای: ultraviolet spectrophotometry
تعداد نتایج: 48877 فیلتر نتایج به سال:
In China, regional haze pollution is a serious environmental problem. The impact on ecosystem, however, is not clearly understood. This study investigates the effect of regional haze pollution on the yields of rice and wheat in China. The spatial and temporal distributions of aerosol optical depth (AOD) show high particulate pollution in the North China Plain region, Yangtze River Delta region,...
One common method of illicit methamphetamine manufacture utilizes an alkali metal, typically lithium, and liquid ammonia to chemically reduce ephedrine or pseudoephedrine to form methamphetamine. This method is often referred to as the lithium-ammonia reduction method or the Birch reduction method. While the hydroxyl group of ephedrine is more reactive than the aromatic ring, excess alkali meta...
BACKGROUND The blackcurrant (Ribes nigrum L.) is a species of native currant which contains a lot of polyphenolic antioxidants which is used medicinally and has a fundamental role in the maintenance health. MATERIALS, METHODS AND OBJECTIVE: Ultraviolet-visible spectrophotometry and ultraviolet range high performance liquid chromatography (HPLC) were used to characterize the polyphenolic content...
We present studies of the Extreme Ultraviolet (EUV) emission in the Fornax cluster of galaxies; a relatively nearby well-studied cluster with X-ray emitting cluster gas and a very large radio source. We examine both the large-scale (∼ size of the X-ray emitting cluster gas), and the small-scale (< arc min) emission. We find that this cluster has large-scale diffuse EUV emission. However, at the...
In this paper we have reviewed our achievements in soft X-ray and extreme ultraviolet (EUV) optics. Up to now, the research system of soft X-ray and EUV optics has been established, including light sources, detectors, calibrations, optical testing and machining of super smooth mirrors, and fabrications of multilayer film mirrors. Based on our achievements, we have developed two types of solar s...
The low expected absorption of Ca in the extreme ultraviolet (EUV) makes it an attractive material for multilayers and filters because most materials in nature strongly absorb the EUV. Few optical constant data had been reported for Ca. In this research, Ca films of various thicknesses were deposited on grid-supported C films and their transmittance measured in situ from the visible to the soft...
We report a proof-of-principle demonstration of a new scheme of spectromicroscopy in the extreme ultraviolet (EUV) spectral range, where the spectral response of the sample at different wavelengths is imaged simultaneously. This scheme is enabled by combining ptychographic information multiplexing (PIM) with a tabletop EUV source based on high harmonic generation, where four spectrally narrow h...
The extreme ultraviolet (EUV) airglow has yet to be studied extensively due to observational difficulties in this range of the spectrum. EURD is an instrument designed to study diffuse EUV radiation flown on the Spanish MINISAT-01 satellite. In this paper we present observations of the terrestrial night airglow as observed from EURD in the range of 400 to 1060 Å. The high sensitivity and high r...
Until now it had been assumed that mammalian skin contains only one provitamin D, 7-dehydrocholesterol, that is eventually converted to vitamin D3 after the skin is exposed to sunlight. Examination by reverse phase high performance liquid chromatography of lipid extracts from young rat skin, however, led to the observation that 7-dehydrocholesterol is not the only provitamin D in rat skin. Anot...
Ultraviolet UV absorbance measurements are subject to significant error using a standard spectrophotometer when particles or aggregates that scatter light are present. True UV absorbance for highly turbid waters should be measured using integrating sphere IS spectrophotometry that allows the collection of reflected and transmitted radiation simultaneously. This is especially important when the ...
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