Search results for "Spectrum"
showing 10 items of 2043 documents
An electrospray ionization mass spectrometric study of the extracellular hemoglobins from Chironomus thummi thummi.
1998
The aquatic larvae of the dipteran, Chironomus thummi thummi contain extracellular hemoglobins which exhibit stage-specific expression. We have used maximum entropy-based deconvolution of the complex, multiply charged electrospray ionization mass spectra, to demonstrate the presence of more than 20 components, ranging in mass from 14,417.3 Da to 17,356.5 Da in the 4th instar larvae. Of the 15 major peaks with intensities > 10 relative to 100 for the 14,417.3 Da-component (CTT-IV), only the 15,528.2-Da peak does not correspond to a known amino acid sequence. Since the number of C. thummi thummi globin genes now stands at 27, including one cDNA and not counting three that must encode known gl…
Determination of sialic acid and gangliosides in biological samples and dairy products: A review
2009
Gangliosides are sphingolipids containing one or more moieties of sialic acid in their structure. Both gangliosides and sialic acid are bioactive compounds related to animal physiology. Due to their biological relevance, analytical methods adapted to each type of matrix have been developed over time. The present study reviews the main methods applied to the analysis of sialic acid and gangliosides in biological samples and dairy products.
Gas chromatographic and mass spectrometric analysis of bile acids as trifluoroacetyl-hexafluoroisopropyl and heptafluorobutyryl derivatives
1981
Abstract The gas chromatographic retention times on QF-1 of 38 bile acids in the form of their trifluoroacetyl-hexafluoroisopropyl (TFA-HFIP), trifluoroacetyl-methyl, and heptafluorobutyryl derivatives are given. In general hexafluoroisopropyl ester trifluoroacetates proved superior with regard to simplicity of preparation, absence of artifacts, and resolution on QF-1. The main disadvantages of heptafluorobutyrates were the production of artifacts with some ketonic bile acids and the impossibility of separating any of the dihydroxy bile acids with substituents in the 3,6- and 3,7-positions. Mass spectra of TFA-HFIP derivatives were recorded with both direct and gas chromatographic inlet sys…
Urban organic aerosol composition in Eastern China differs from North to South: Molecular insight from a liquid chromatography-Orbitrap mass spectrom…
2019
Particulate air pollution in China is influencing human health, ecosystem and climate. However, the chemical composition of particulate aerosol, especially of the organic fraction, is still not well understood. In this study, particulate aerosol samples with a diameter ≤ 2.5 μm (PM2.5) were collected in January 2014 in three cities located in Northeast, East and Southeast China, i.e., Changchun, Shanghai and Guangzhou, respectively. Organic aerosol (OA) in the PM2.5 samples was analyzed by ultrahigh performance liquid chromatography (UHPLC) coupled to high-resolution Orbitrap mass spectrometry in both negative mode (ESI−) and positive mode electrospray ioni…
Characteristic Topological Features of Promoter Capture Hi-C Interaction Networks
2020
Current Hi-C technologies for chromosome conformation capture allow to understand a broad spectrum of functional interactions between genome elements. Although significant progress has been made into analysis of Hi-C data to identify the biologically significant features, many questions still remain open. In this paper we describe analysis methods of Hi-C (specifically PCHi-C) interaction networks that are strictly focused on topological properties of these networks. The main questions we are trying to answer are: (1) can topological properties of interaction networks for different cell types alone be sufficient to distinguish between these types, and what the most important of such propert…
Antennas for the detection of radio emission pulses from cosmic-ray induced air showers at the Pierre Auger Observatory.
2012
The Pierre Auger Observatory is exploring the potential of the radio detection technique to study extensive air showers induced by ultra-high energy cosmic rays. The Auger Engineering Radio Array (AERA) addresses both technological and scientific aspects of the radio technique. A first phase of AERA has been operating since September 2010 with detector stations observing radio signals at frequencies between 30 and 80 MHz. In this paper we present comparative studies to identify and optimize the antenna design for the final configuration of AERA consisting of 160 individual radio detector stations. The transient nature of the air shower signal requires a detailed description of the antenna s…
Searches for Large-Scale Anisotropy in the Arrival Directions of Cosmic Rays Detected above Energy of $10^{19}$ eV at the Pierre Auger Observatory an…
2014
Spherical harmonic moments are well-suited for capturing anisotropy at any scale in the flux of cosmic rays. An unambiguous measurement of the full set of spherical harmonic coefficients requires full-sky coverage. This can be achieved by combining data from observatories located in both the northern and southern hemispheres. To this end, a joint analysis using data recorded at the Telescope Array and the Pierre Auger Observatory above 1019 eV is presented in this work. The resulting multipolar expansion of the flux of cosmic rays allows us to perform a series of anisotropy searches, and in particular to report on the angular power spectrum of cosmic rays above 1019 eV. No significant devia…
Instantaneous frequency measurement of dissipative soliton resonant light pulses
2016
Fil: Cuadrado-Laborde, Christian. Universidad de Valencia. Departamento de Física Aplicada y Electromagnetismo. Instituto Universitario de Ciencia de los Materiales; España Fil: Cuadrado-Laborde, Christian. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Rosario; Argentina Fil: Cuadrado-Laborde, Christian. Pontificia Universidad Católica Argentina. Facultad de Química e Ingeniería del Rosario; Argentina Fil: Armas Rivera, I. Benemérita Universidad Autónoma de Puebla. Facultad de Ciencias Físico Matemáticas; Mexico Fil: Carrascosa, A. Universidad de Valencia. Departamento de Física Aplicada y Electromagnetismo. Instituto Universitario de Ciencia de los Materia…
Characterization of gramicidin A in an inverted micellar environment. A combined high-performance liquid chromatographic and spectroscopic study
1992
We have investigated the conformational adaptability of gramicidin A incorporated into reverse micelles of sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/isooctane/water, a so far unexplored "host" membrane-mimetic model system for this peptide. A high-performance liquid chromatographic strategy previously developed for the study of gramicidin in phospholipid vesicles and normal micelles [Bañó et al. (1989) FEBS Lett. 250, 67; Bañó et al. (1991) Biochemistry 30, 886] has been successfully extended to this system. The method has permitted the separation of peptide conformational species, namely, double-stranded dimers and monomers, and an accurate quantitation of their proportion in the invert…
The interaction of native DNA with iron(III)- N ,N'-ethylene-bis(salicylideneiminato)-chloride.
2004
Abstract The interaction between native calf thymus deoxyribonucleic acid (DNA) and Fe III - N , N ′ -ethylene-bis (salicylideneiminato)-chloride, Fe(Salen)Cl, was investigated in aqueous solutions by UV–visible (UV–vis) absorption, circular dichroism (CD), thermal denaturation and viscosity measurements. The results obtained from CD, UV–vis and viscosity measurements exclude DNA intercalation and can be interpreted in terms of an electrostatic binding between the Fe(Salen) + cation and the phosphate groups of DNA. The trend of the UV–vis absorption band of the Fe(Salen)Cl complex at different ratios [DNA phosphate ]/[Fe(Salen)Cl] and the large increase of the melting temperature of DNA in …