نتایج جستجو برای: absorbance spectra

تعداد نتایج: 116379  

Journal: :Environmental science & technology 2016
Lelia N Hawkins Amanda N Lemire Melissa M Galloway Ashley L Corrigan Jacob J Turley Brenna M Espelien David O De Haan

The reported optical, physical, and chemical properties of aqueous Maillard reaction mixtures of small aldehydes (glyoxal, methylglyoxal, and glycolaldehyde) with ammonium sulfate and amines are compared with those of aqueous extracts of ambient aerosol (water-soluble organic carbon, WSOC) and the humic-like substances (HULIS) fraction of WSOC. Using a combination of new and previously publishe...

2003
Oscar Hernandez Francisco Jimenez Ana Isabel Jimenez

A partial least-squares multivariate calibration method for the resolution of mixtures of metal ions from the spectra of the complexes produced in a flow injection (FI) system has been developed. The method has been applied to the simultaneous determination of Cull and Znii with 4-(4'-methyl-2'-thiazolylazo)-2-methylresorcinol. The reagent exhibits a high absorbance and its spectrum strongly ov...

2000
Anthony J. Owen

Derivative spectroscopy uses first or higher derivatives of absorbance with respect to wavelength for qualitative analysis and for quantification. The concept of derivatizing spectral data was first introduced in the 1950s, when it was shown to have many advantages. However, the technique received little attention primarily because of the complexity of generating derivative spectra using early ...

Journal: :Nucleic acids research 1979
D Frechet R Ehrlich P Remy

A relatively important change in UV absorption is observed upon thermal perturbation of nucleotide solutions. Comparison of these thermal perturbation spectra of nucleic acid residues with solvent perturbation spectra of the same compounds suggests that this spectral change can most probably be attributed to temperature induced hydration change of the bases. This conclusion is confirmed by the ...

Journal: :Nucleic Acids Research 2005
Jean-Louis Mergny Jing Li Laurent Lacroix Samir Amrane Jonathan B. Chaires

We show that nucleic acid structures may be conveniently and inexpensively characterized by their UV thermal difference spectra. A thermal difference spectrum (TDS) is obtained for a nucleic acid by simply recording the ultraviolet absorbance spectra of the unfolded and folded states at temperatures above and below its melting temperature (T(m)). The difference between these two spectra is the ...

H. Seradj N. Mehrabi S. Hemmati

Background and objectives: Residues of medicinal plants after extraction and weeds are suitable candidates for bioethanol production. Significant barriers exist to make the conversion of lignocellulosic feedstock to biofuel cost effective and environmentally friendly; one of which is the lignin polymer. Brassicaceae family is one of the potential targets for biofuel production....

2017
Francis A. Haskins Herman J. Gorz R. M. Hill J. Brakke Youngquist

When dhurrin [p-hydroxy-(S)-mandelonitrile-tJ-D-glucoside], the cyanogenic glucoside of sorghum [Sorghum bicolor (L.) Moench], is hydrolyzed by autoclaving, p-hydroxybenzaldehyde (P-HB) is released. The spectrophotometric determination of pHB concentration in autoclaved sorghum leaf extracts provides a measure of the hydrocyanic acid potential (HCN-p) of leaf tissue. Extracts of field-grown sor...

Journal: :journal of reports in pharmaceutical sciences 0
mohsen shahlaei department of medicinal chemistry, faculty of pharmacy, kermanshah university of medical sciences, kermanshah, po box: 67145-1673, and nanosciences and technology research center, kermanshah university of medical sciences, kermanshah, iran hadi andisheh katayoun derakhshandeh komail sadr havadi mahsa azami

a sensitive and selective method using combination of principal component analysis (pca), artificial neural network (ann) and uv-visible spectroscopy has been developed for the simultaneous determination of acetaminophen (amp) and codeine (cod) in plasma samples. the ann trained by the back-propagation learning was employed to model the complex non-linear relationship between the pcs extracted ...

Journal: :Journal of physics 2023

Abstract The magneto-optical (transmittance, absorbance, and reflectance) characteristics of water saltwater in the presence a magnetic field (0T to 0.880T) are investigated this study. authors studies Raman spectra shift response fields. In case water, transmittance is high field, but saltwater, low at wavelength spectrum. was found be 0.7 percent higher 0.88T than absence 651nm–655.67nm. Simi...

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