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Published in Heinz P. Bloch, Kenneth E. Bannister, Practical Lubrication for Industrial Facilities, 2020
Heinz P. Bloch, Kenneth E. Bannister
Chromatography is an analytical technique involving the flow of a gas or liquid, together with the material under analysis, over a special porous, insoluble, sorptive medium. As the flowing phase passes over the stationary phase, different hydrocarbon components are adsorbed preferentially by the medium. With some types of chromatography, these components are desorbed through a similar process, and they leave the chromatographic column in distinct individual patterns. These patterns can be detected and recorded, and with proper interpretation can provide an extremely accurate means of determining composition. Chromatography is used in both carbon-type and molecular-type analyses. There are a number of chromatographic methods, each named according to the technique of analysis. Gas chromatography refers to the general method that uses a gas as the flowing, or mobile, phase; gas liquid chromatography, a more specific term, describes the techniques of using gas as the flowing phase and a liquid as the stationary phase; etc.
Characterization Techniques for Bio-Nanocomposites
Published in Shrikaant Kulkarni, Neha Kanwar Rawat, A. K. Haghi, Green Chemistry and Green Engineering, 2020
The purpose of chemical analytical techniques is to estimate the nature of the elements present in a given sample, their relative amount, and the chemical interactions between them. In principle, the composition of the reagents used for the synthesis and their chemical routes present an indication of various elements found in the ultimate product. However, unreacted species, impurities, or by products of the reaction may also be present that need to be identified. Thus, techniques that provides a simultaneous indication of all present elements and is better over other techniques which are confined to a single element, unless a precise titration of a given element is necessary.
Polymer Semiconductors
Published in Inamuddin, Mohd Imran Ahamed, Rajender Boddula, Tariq Altalhi, Polymers in Energy Conversion and Storage, 2022
Moises Bustamante-Torres, Jocelyne Estrella-Nuñez, Odalys Torres, Sofía Abad-Sojos, Bryan Chiguano-Tapia, Emilio Bucio
Mass spectrometry (MS) is a widely used analytical technique that measures the mass-to-charge ratios of atoms and molecules. MS requires an external device to introduce the sample that could be gas chromatography, liquid chromatography, or capillary electrophoresis. MS produces ions in the gas phase then, and a mass analyzer separates the ions according to their mass-to-charge ratios. Finally, the detector counts the ions (De Hoffmann 2005). MS provides high precision, accuracy, selectivity, and sensibility of detection to determine molecular weight (Gmoshinskii et al. 2013).
Buckling analysis of cracked laminated plates by domain decomposition method
Published in Ships and Offshore Structures, 2019
Solving partial differential equations is one of the most significant ways to answer an applied problem. However, analytical techniques cannot always be used, their usage is limited to simplified problems. FEM is widely used to solve complex problems but FEM is a low-order numerical tool. In the ordinary FEM, the displacements are continuous, but the stresses, which are first-order derivatives of displacements, are discontinuous. Thus, the accuracy of FEM is low and the rate of accuracy related to mesh density. So the high order numerical methods at the cost of low mesh density are essential. DQM is a cost-effective tool for solving many non-linear partial differential equations. In the last few decades, DQM is presented for solving different engineering problems, such as aerodynamics and fracture mechanics. The DQM possesses the capability to yield accurate results with minimal computational efforts. The problems with discontinuities in material, geometry and boundary conditions cannot deal with the classical version of the DQM. So, a new version based on domain decomposition idea is required for solving discontinuity problems. In fact, based on the DQM and domain decomposition idea, the whole physical domain is separated into a certain number of sub-domains according to the various discontinuities. On this basis, developed the differential quadrature element method for static, vibrating analyses of discontinuous isotropic plates (Liu and Liew 1998; Liu and Liew 1999a, 1999b). As well as, Liu (2001) has investigated buckling analysis of isotropic plates with different discontinuities based on the DQM and domain decomposition. The objective of this paper is to expand the GDQ method and domain decomposition idea in cracked laminated plates.
Identification and characterization of amiodarone metabolites in rats using UPLC–ESI-QTOFMS-based untargeted metabolomics approach
Published in Journal of Toxicology and Environmental Health, Part A, 2018
Eun Sook Jeong, Gabin Kim, Daeun Yim, Kyung-Sik Moon, Su-Jun Lee, Jae-Gook Shin, Dong Hyun Kim
Amiodarone is extensively metabolized and less than 1% of the drug is excreted unchanged in the urine (Latini, Tognoni, and Kates 1984). Amiodarone is structurally complex, and various metabolic reactions may be expected, including hydroxylation, de-ethylation, carboxylation, de-iodination, deamination, and glucuronidation. The amiodarone metabolites of hepatic microsomes were determined (Elsherbiny, El-Kadi, and Brocks 2008; Young and Mehendale 1986), as those generated in experimental animals and humans (Deng et al. 2011; Ha et al. 2001). Mono-N-desethyl amiodarone and di-desethyl amiodarone were identified as major metabolites both in vitro and in vivo (Deng et al. 2011; Ohyama et al. 2000). However, the number of minor metabolites ranged from a few to more than 30 depending upon the matrix and experimental tools used. It is difficult to identify low-level amiodarone metabolites in vivo by simple manual examination of liquid chromatography-mass spectrometry (LC–MS) chromatograms of plasma and urine samples, because of interference by endogenous compounds. Therefore, more systematic tools are required to identify all possible metabolites. Several studies reported that metabolomics approach might be useful to identify unknown drug metabolites in complex biological fluids (Kim et al. 2017; Plumb et al. 2003; Wu et al. 2015; Xing et al. 2015). The analytical techniques employed include nuclear magnetic resonance (NMR) spectroscopy, gas chromatography-mass spectrometry, and LC-MS. Of these, high-resolution LC-MS is a promising tool enabling identification of xenobiotic-derived metabolites (Fang and Gonzalez 2014). Thus, the aim of the present study was to use a liquid chromatography-quadrupole time-of-flight (LC-QTOF)-based untargeted metabolomic approach to identify amiodarone-derived metabolites in rat plasma and urine in order to determine underlying systematic amiodarone metabolism.
Origin of carbonate cements and reservoir evolution of tight sandstone in the Upper Triassic Yanchang Formation, Ordos Basin, China
Published in Australian Journal of Earth Sciences, 2019
S. W. Mao, Z. D. Bao, X. X. Wang, Y. S. Gao, J. Song, Z. C. Wang, W. Liu, L. Zhang, M. Y. Wei, Y. F. Bao
A total of 327 core samples used in this research were collected from the Chang 8 Member in the Jiyuan area, Ordos Basin. The main analytical techniques include thin-section identification, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffractometry (XRD), pressure-controlled/rate-controlled porosimetry (PCP/RCP), fluid inclusion analysis, and geochemical analysis (carbon and oxygen isotope analysis).