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Analytical chemistry

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https://www.readbyqxmd.com/read/28448125/efficient-computation-of-exchange-energy-density-with-gaussian-basis-functions
#1
Fenglai Liu, Jing Kong
Density Functional Theory(DFT) is widely applied in chemistry and Physics. Still it fails to predict correctly quantitatively or even qualitatively for systems with significant nondynamic correlations. Several DFT functionals were proposed in recently years to treat nondynamic correlation, most of which added the exact exchange energy density as a new variable, which becomes the computational bottleneck for calculations with these new functionals We present an implementation of an efficient seminumerical algorithm in this paper as a solution for this computational bottleneck...
April 27, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28446924/differential-leukocyte-counting-via-fluorescent-detection-and-image-processing-on-a-centrifugal-microfluidic-platform
#2
Max L Balter, Alvin I Chen, C Amara Colinco, Alexander Gorshkov, Brian Bixon, Vincent Martin, Alexander Fromholtz, Timothy J Maguire, Martin L Yarmush
Centrifugal microfluidics has received much attention in the last decade for the automation of blood testing at the point-of-care, specifically for the detection of chemistries, proteins, and nucleic acids. However, the detection of common blood cells on-disc, particularly leukocytes, remains a challenge. In this paper, we present two analytical methods for enumerating leukocytes on a centrifugal platform using a custom-built fluorescent microscope, acridine orange nuclear staining, and image processing techniques...
December 21, 2016: Analytical Methods: Advancing Methods and Applications
https://www.readbyqxmd.com/read/28445767/the-visualized-macrocycles-chemistry-and-application-of-fluorophore-tagged-cyclodextrins
#3
Gábor Benkovics, Milo Malanga, Éva Fenyvesi
Cyclodextrins are macrocyclic molecules able to form host-guest complexes due to their hydrophobic cavity. Because of their carbohydrate nature they do not absorb light in the UV-vis region (200-800nm), but they can be converted into spectroscopically active compounds via modification with a chromophore unit. Among the chromophores, the group of fluorophores can provide high sensitivity in analytical applications (chemosensing) and low detection limit in optical imaging methods (fluorescent microscopy). Fluorophore-tagged cyclodextrins therefore combine interesting spectroscopic properties with promising supramolecular features which make these conjugates widely applicable in various pharmaceutical fields...
April 23, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28438425/mobile-laboratories-an-innovative-and-efficient-solution-for-radiological-characterization-of-sites-under-or-after-decommissioning
#4
V Goudeau, B Daniel, D Dubot
During the operation and the decommissioning of a nuclear site the operator must assure the protection of the workers and the environment. It must furthermore identify and classify the various wastes, while optimizing the associated costs. At all stages of the decommissioning radiological measurements are performed to determine the initial situation, to monitor the demolition and clean-up, and to verify the final situation. Radiochemical analysis is crucial for the radiological evaluation process to optimize the clean-up operations and to the respect limits defined with the authorities...
April 21, 2017: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/28433435/fabric-phase-sorptive-extraction-as-a-reliable-tool-for-rapid-screening-and-detection-of-freshness-markers-in-oranges
#5
M Aznar, S Úbeda, C Nerin, A Kabir, K G Furton
A simple, fast and sensitive analyte extraction method based on fabric phase sorptive extraction (FPSE) followed by gas chromatography-mass spectrometry (GC-MS) and ultra-performance liquid chromatography-quadrupole time of flight mass spectrometry (UPLC-QTOF-MS) analysis was developed for the analysis of 12 volatile compounds that represent most of the principal chemical families possessing different polarities and volatilities. Five FPSE media coated with different sol-gel sorbent chemistries having different polarities and selectivities were studied: long chain poly(dimethylsiloxane) (PDMS), short chain poly(tetrahydrofuran) (PTHF), Carbowax 20M (CW20M), short chain poly(dimethyl siloxane) (SC PDMS) and polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer (PEG-PPG-PEG)...
April 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28433052/metabolomics-strategies-to-define-the-role-of-metabolism-in-virus-infection-and-pathogenesis
#6
Marianne Manchester, Anisha Anand
Metabolomics is an analytical profiling technique for measuring and comparing large numbers of metabolites present in biological samples. Combining high-throughput analytical chemistry and multivariate data analysis, metabolomics offers a window on metabolic mechanisms. Because they intimately utilize and often rewire host metabolism, viruses are an excellent choice to study by metabolomics techniques. Studies of the effects of viruses on metabolism during replication in vitro and infection in animal models or human subjects have provided novel insights into these networks and provided new targets for therapy and biomarker development...
2017: Advances in Virus Research
https://www.readbyqxmd.com/read/28428356/biological-variation-estimates-obtained-from-91-healthy-study-participants-for-9-enzymes-in-serum
#7
Anna Carobene, Thomas Røraas, Una Ørvim Sølvik, Marit Sverresdotter Sylte, Sverre Sandberg, Elena Guerra, Irene Marino, Niels Jonker, Gerhard Barla, William A Bartlett, Pilar Fernandez-Calle, Jorge Díaz-Garzón, Francesca Tosato, Mario Plebani, Abdurrahman Coŝkun, Mustafa Serteser, Ibrahim Unsal, Ferruccio Ceriotti
BACKGROUND: We sought to develop estimates of biological variation (BV) for 9 enzymes in blood serum as part of the European Biological Variation Study. METHODS: Ninety-one healthy study participants (38 male and 53 female, 21-69 years old) were phlebotomized in each of 10 consecutive weeks at 6 European laboratories. The same preanalytical sample-handling protocol was followed at each center before transport to San Raffaele Hospital, Milan, Italy, for analysis...
April 20, 2017: Clinical Chemistry
https://www.readbyqxmd.com/read/28426053/improved-spatial-resolution-for-spot-sampling-in-thermal-desorption-atomic-force-microscopy-mass-spectrometry-via-rapid-heating-functions
#8
Suhas Somnath, Stephen Jesse, Gary J Van Berkel, Sergei V Kalinin, Olga S Ovchinnikova
The key to advancing materials is to understand and control their structure and chemistry. However, thorough chemical characterization is challenging since existing techniques characterize only a few properties of the specimen, thereby necessitating multiple measurement platforms to acquire the necessary information. The multimodal combination of atomic force microscopy (AFM) and mass spectrometry (MS) transcends existing analytical capabilities for nanometer scale spatially resolved correlation of the chemical and physical properties of a sample surface...
April 20, 2017: Nanoscale
https://www.readbyqxmd.com/read/28419525/method-comparison-and-generation-of-plasma-biochemistry-ris-for-the-white-rhinoceros-on-a-point-of-care-and-wet-chemistry-analyzer
#9
Emma H Hooijberg, Gerhard Steenkamp, Peter Buss, Amelia Goddard
BACKGROUND: Plasma biochemistry analysis may aid the management of White rhinoceros with poaching or other injuries. Analyzer- and species-specific RIs are necessary to evaluate health status and identify abnormalities. OBJECTIVES: The purpose of the study was to perform a comparison study between the IDEXX VetTest and Roche Cobas Integra 400 Plus, and to generate analyzer-specific RIs for White rhinoceros according to published guidelines. METHODS: Comparison was carried out using White rhinoceros plasma samples from healthy and diseased animals...
April 17, 2017: Veterinary Clinical Pathology
https://www.readbyqxmd.com/read/28407597/layer-by-layer-deposition-on-a-heterogeneous-surface-effect-of-sorption-kinetics-on-the-growth-of-polyelectrolyte-multilayers
#10
Hervé Bellanger, Kirstin Casdorff, Livius F Muff, Rebecca Ammann, Ingo Burgert, Benjamin Michen
Surface functionalization by means of controlled deposition of charged polymers or nanoparticles using the layer-by-layer (LbL) approach has been used to modify mostly engineered materials with well-defined surface chemistry and morphology. In this regard, natural and inhomogeneous interfaces have gained very little attention. Furthermore, natural substrates are susceptible to alterations by factors commonly used to control the growth of multilayers, such as pH, temperature and ionic strength. Here, we study the impact of sorption kinetics of a bilayer system (Poly(diallyldimethylammonium chloride) (PDDA) and Poly(sodium 4-styrenesulfonate) (PSS)) on a natural heterogeneous wood surface at neutral pH, without salt addition, on the multilayer buildup...
February 22, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28407236/processes-to-preserve-spice-and-herb-quality-and-sensory-integrity-during-pathogen-inactivation
#11
Susan E Duncan, Kayla Moberg, Kemia N Amin, Melissa Wright, Jordan J Newkirk, Monica A Ponder, Gary R Acuff, James S Dickson
Selected processing methods, demonstrated to be effective at reducing Salmonella, were assessed to determine if spice and herb quality was affected. Black peppercorn, cumin seed, oregano, and onion powder were irradiated to a target dose of 8 kGy. Two additional processes were examined for whole black peppercorns and cumin seeds: ethylene oxide (EtO) fumigation and vacuum assisted-steam (82.22 °C, 7.5 psia). Treated and untreated spices/herbs were compared (visual, odor) using sensory similarity testing protocols (α = 0...
April 13, 2017: Journal of Food Science
https://www.readbyqxmd.com/read/28406603/jonathan-w-amy-and-the-amy-facility-for-instrumentation-development
#12
R Graham Cooks
The article describes the unique Jonathan Amy Facility for Chemical Instrumentation in the Department of Chemistry at Purdue University, tracing its history and mode of operation. It also describes aspects of the career of its namesake and some of his insights which have been central to analytical instrumentation development, improvement and utilization, both at Purdue and nationally.
April 13, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28400750/methylation-on-rna-a-potential-mechanism-related-to-immune-priming-within-but-not-across-generations
#13
Cynthia Castro-Vargas, César Linares-López, Adolfo López-Torres, Katarzyna Wrobel, Juan C Torres-Guzmán, Gloria A G Hernández, Kazimierz Wrobel, Humberto Lanz-Mendoza, Jorge Contreras-Garduño
Invertebrate immune priming is a growing field in immunology. This phenomenon refers to the ability of invertebrates to generate a more vigorous immune response to a second encounter with a specific pathogen and can occur within and across generations. Although the precise mechanism has not been elucidated, it has been suggested that methylation of DNA is a cornerstone for this phenomenon. Here, using a novel method of analytical chemistry (a reversed-phase liquid chromatography procedure) and the beetle Tenebrio molitor as a model system, we did not find evidence to support this hypothesis taking into account the percentage of methylated cytosine entities in DNA (5mdC) within or across generations...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28398631/intraband-optical-activity-of-semiconductor-nanocrystals
#14
Anvar S Baimuratov, Nikita V Tepliakov, Yurii K Gun'Ko, Alexey G Shalkovskiy, Alexander V Baranov, Anatoly V Fedorov, Ivan D Rukhlenko
Here we review our three recently developed analytical models describing the intraband optical activity of semiconductor nanocrystals, which is induced by screw dislocations, ionic impurities, or irregularities of the nanocrystal surface. The models predict that semiconductor nanocrystals can exhibit strong optical activity upon intraband transitions and have large dissymmetry of magnetic-dipole absorption. The developed models can be used to interpret experimental circular dichroism spectra of nanocrystals and to advance the existing techniques of enantioseparation, biosensing, and chiral chemistry...
May 2017: Chirality
https://www.readbyqxmd.com/read/28398080/new-polymeric-materials-for-solid-phase-extraction
#15
Justyna Płotka-Wasylka, Mariusz Marć, Natalia Szczepańska, Jacek Namieśnik
Solid phase extraction (SPE) is a popular sample preparation technique, which can be applied directly in gas-solid phase and liquid-solid phase, or indirectly to solid samples by using, e.g., thermodesorption with subsequent chromatographic analysis. Although SPE can be described as a physical extraction process involving a liquid phase and a solid phase, the increased use of packed sorbent formats seems to have led to a bias toward packed sorbent SPE devices. Without any doubt, the heart of the SPE technique is the sorbent material as it has a direct influence on the selectivity, sorptive capacity, and the format or the configuration of the resultant SPE device...
April 11, 2017: Critical Reviews in Analytical Chemistry
https://www.readbyqxmd.com/read/28392726/interpretation-of-eqa-results-and-eqa-based-trouble-shooting
#16
REVIEW
Gunn Berit Berge Kristensen, Piet Meijer
Important objectives of External Quality Assessment (EQA) is to detect analytical errors and make corrective actions. The aim of this paper is to describe knowledge required to interpret EQA results and present a structured approach on how to handle deviating EQA results. The value of EQA and how the EQA result should be interpreted depends on five key points: the control material, the target value, the number of replicates, the acceptance limits and between lot variations in reagents used in measurement procedures...
February 15, 2017: Biochemia Medica: časopis Hrvatskoga Društva Medicinskih Biokemičara
https://www.readbyqxmd.com/read/28391863/evaluation-of-new-natural-deep-eutectic-solvents-for-the-extraction-of-isoflavones-from-soy-products
#17
Sylwia Bajkacz, Jakub Adamek
Natural deep eutectic solvents (NADESs) are considered to be new, safe solvents in green chemistry that can be widely used in many chemical processes such as extraction or synthesis. In this study, a simple extraction method based on NADES was used for the isolation of isoflavones (daidzin, genistin, genistein, daidzein) from soy products. Seventeen different NADES systems each including two or three components were tested. Multivariate data analysis revealed that NADES based on a 30% solution of choline chloride: citric acid (molar ratio of 1:1) are the most effective systems for the extraction of isoflavones from soy products...
June 1, 2017: Talanta
https://www.readbyqxmd.com/read/28390485/direct-coupling-of-thin-layer-chromatography-bioautography-with-electrostatic-field-induced-spray-ionization-mass-spectrometry-for-separation-and-identification-of-lipase-inhibitors-in-lotus-leaves
#18
Lei Zhang, Jiyao Shi, Jihe Tang, Zhihong Cheng, Xiaohui Lu, Yao Kong, Tao Wu
In situ profiling compounds in complex matrices is important technology to develop in analytic chemistry. The aim of this study is to develop a direct coupling method of thin layer chromatography (TLC) to mass spectrometry (MS) via electrostatic field induced spray ionization (EFISI). We proposed a surface treatment method of normal-phase thin layer chromatography (TLC) plates with dimethyl silicone oil coating which successfully allowed TLC to couple to MS via EFISI. Different parameters affecting the ionization efficiency were investigated and optimized, including silicone oil concentrations, air-drying times, applied voltages, and TLC plate types...
May 15, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28389917/a-green-analytical-chemistry-approach-for-lipid-extraction-computation-methods-in-the-selection-of-green-solvents-as-alternative-to-hexane
#19
Mari Merce Cascant, Cassandra Breil, Salvador Garrigues, Miguel de la Guardia, Anne Silvie Fabiano-Tixier, Farid Chemat
There is a great interest in finding alternatives and green solvents in extraction processes to replace petroleum based solvents. In order to investigate these possibilities, computational methods, as Hansen solubility parameters (HSP) and conductor-like screening model for real solvent (COSMO-RS), were used in this work to predict the solvation power of a series of solvents in salmon fish lipids. Additionally, experimental studies were used to evaluate the performance in lipids extraction using 2-methyltetrahydrofurane, cyclopentyl methyl ether, dimethyl carbonate, isopropanol, ethanol, ethyl acetate, p-cymene and d-limonene compared with hexane...
April 7, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28388031/identification-of-lanthanide-iii-luminophores-in-magnetic-circularly-polarized-luminescence-using-raman-optical-activity-instrumentation
#20
Tao Wu, Josef Kapitán, Valery Andrushchenko, Petr Bouř
Luminescence of lanthanide(III) ions sensitively reflects atomic environment. However, the signal may be weak and covered by Raman scattering. In the present study magnetic circularly polarized luminescence (MCPL) is explored as a more sensitive tool to recognize the lanthanide signal and assign underlying electronic transitions. MCPL spectra of the Na3[Ln(DPA)3] (Ln = Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, and Er) complexes were recorded on a Raman optical activity (ROA) instrument. The ROA spectrometer equipped with the 532 nm laser excitation sensitively detects differences in scattering of left- and right-circularly polarized light caused by the magnetic field...
April 13, 2017: Analytical Chemistry
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