keyword
MENU ▼
Read by QxMD icon Read
search

Mass spectra

keyword
https://www.readbyqxmd.com/read/28926221/fourier-transform-ms-and-closed-path-multi-reflection-time-of-flight-ms-using-an-electrostatic-linear-ion-trap
#1
Eric T Dziekonski, Joshua T Johnson, Kenneth W Lee, Scott A McLuckey
An electrostatic linear ion trap (ELIT) has been configured to allow for the simultaneous acquisition of mass spectra via Fourier transform (FT) techniques (frequency measurement) and via time-of-flight (TOF) (time measurement). In the former case, the time-domain image charge derived from a pick-up electrode in the field-free region of the ELIT is converted to frequency-domain data via Fourier transformation (i.e., FT-ELIT MS). In the latter case, the time difference between ion injection into the ELIT and ion detection after release from the ELIT using a micro-channel plate (MCP) enables the acquisition of multi-reflection time-of-flight mass spectra (MR-TOF MS)...
September 19, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28925699/ab-initio-computation-of-energy-deposition-during-electron-ionization-of-molecules
#2
Karl K Irikura
The dissociative ionization of molecules under electron impact forms the basis for analytical mass spectrometry of volatile compounds. It is also important in other situations, notably plasmas. Although qualitative theory for mass spectrometry was developed long ago, progress toward predictive theory has been slow. A major obstacle has been ignorance of the amount of energy deposited in the molecular ion, prior to its fragmentation. Here, we consider the Binary-Encounter Bethe (BEB) theory, which was originally developed for predicting total ionization cross sections...
September 19, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28922568/spectral-libraries-for-swath-ms-assays-for-drosophila-melanogaster-and-solanum-lycopersicum
#3
Bertrand Fabre, Dagmara Korona, Clara I Mata-Martinez, Harriet T Parsons, Michael J Deery, Maarten L A T M Hertog, Bart M Nicolaï, Steven Russell, Kathryn S Lilley
Quantitative proteomics methods have emerged as powerful tools for measuring protein expression changes at the proteome level. Using mass-spectrometry (MS) based approaches, it is now possible to routinely quantify thousands of proteins. However, pre-fractionation of the samples at the protein or peptide level is usually necessary to go deep into the proteome, increasing both MS analysis time and technical variability. Recently, a new MS acquisition method named SWATH was introduced with the potential to provide good coverage of the proteome as well as a good measurement precision without prior sample fractionation...
September 18, 2017: Proteomics
https://www.readbyqxmd.com/read/28921388/immunomodulatory-potential-of-nanocurcumin-based-formulation
#4
Mahendra Kumar Trivedi, Sambhu Charan Mondal, Mayank Gangwar, Snehasis Jana
Vitamins, minerals, and nanocurcumin play a substantial role in various nutraceutical/pharmaceutical formulations that are widely used in therapeutics, cosmetics, and dietary supplements. The current study aimed to investigate the comparative in vitro immunomodulatory effect of a novel nanocurcumin-based formulation with curcumin in LPS-induced cytokine expression, NK cells' activity, and phagocytosis. The proinflammatory cytokines (TNF-α, IL-1β, and MIP-1α) and NK cells' activity were measured in cell supernatants using ELISA assay; however, phagocytosis activity was performed using colorimetric analysis...
September 18, 2017: Inflammopharmacology
https://www.readbyqxmd.com/read/28920600/quantum-state-selected-integral-cross-sections-for-the-charge-transfer-collision-of-o2-a-4-%C3%AE-u5-2-3-2-1-2-1-2-v-1-2-j-o2-x-2-%C3%AE-g3-2-1-2-v-22-23-j-ar-at-center-of-mass-collision-energies-of-0-05-10-00-ev
#5
Bo Xiong, Yih-Chung Chang, Cheuk-Yiu Ng
By employing the sequential electric field pulsing scheme for vacuum ultraviolet (VUV) laser pulsed field ionization-photoion (PFI-PI) detection, we have successfully recorded the spin-orbit and rovibronic state resolved VUV-PFI-PI spectra for O2(+)(a(4)Πu5/2,3/2,1/2,-1/2: ν(+) = 0-2; J(+)) and O2(+)(X(2)Πg3/2,1/2: ν(+) = 21-23; J(+)), indicating that O2(+)(a(4)Πu) and O2(+)(X(2)Πg) ions in these spin-orbit and rovibronic states can be prepared for ion-molecule collision studies. The present experiment is concerned with the measurement of absolute integral cross sections (σ's) of the charge transfer reactions, O2(+)(a(4)Πu5/2,3/2,1/2,-1/2: ν(+) = 1, 2; J(+)) [O2(+)(X(2)Πg1/2,3/2: ν(+) = 22, 23)] + Ar → Ar(+) + O2...
September 18, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28920441/new-insight-of-common-regulatory-pathways-in-human-trabecular-meshwork-cells-in-response-to-dexamethasone-and-prednisolone-using-an-integrated-quantitative-proteomics-swath-and-mrm-hr-mass-spectrometry
#6
Sze Wan Shan, Chi Wai Do, Thomas Chuen Lam, Ricky Pak Wing Kong, King Kit Li, Ka Man Chun, William Daniel Stamer, Chi Ho To
The molecular pathophysiology of corticosteroid-induced ocular hypertension (CIH) is not well understood. To determine the biological mechanisms of CIH, this study investigated protein expression profiles of human trabecular meshwork (hTM) cells in response to dexamethasone and prednisolone treatment. Both discovery-based Sequential Windowed data independent Acquisition of the Total High-resolution mass spectra (SWATH(TM)-MS) and targeted based high resolution multiple reaction monitoring (MRM-HR) confirmation were applied using a hybrid quadrupole-time-of-flight mass spectrometer...
September 18, 2017: Journal of Proteome Research
https://www.readbyqxmd.com/read/28919876/peptide-composition-of-stroke-causing-emboli-correlate-with-serum-markers-of-atherosclerosis-and-inflammation
#7
Neal M Rao, Joseph Capri, Whitaker Cohn, Maram Abdaljaleel, Lucas Restrepo, Jeffrey A Gornbein, William H Yong, David S Liebeskind, Julian P Whitelegge
INTRODUCTION: The specific protein composition of stroke-causing emboli is unknown. Because ischemic stroke has a varied etiology, it is possible that the composition of the thrombus from which an embolus originated will have distinctive molecular characteristics reflective of the underlying pathophysiology. We used mass spectrometry to evaluate the protein composition of retrieved emboli from patients with differing stroke etiologies and correlated the protein levels to serum predictors of atherosclerosis...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28918083/topical-fluorometholone-treatment-and-desiccating-stress-change-inflammatory-protein-expression-in-tears
#8
Janika Nättinen, Antti Jylhä, Ulla Aapola, Amalia Enríquez-de-Salamanca, José Pinto-Fraga, Alberto López-Miguel, María J González-García, Michael E Stern, Margarita Calonge, Lei Zhou, Matti Nykter, Hannu Uusitalo, Roger Beuerman
PURPOSE: It was hypothesized that tear protein biomarkers could predict the effects of topical steroid treatment and desiccating stress in patients with dry eye disease (DED). To test this concept, a randomized, double-masked, controlled clinical trial with 41 patients was conducted. METHODS: The patients were treated topically with either 0.1% fluorometholone (FML) or polyvinyl alcohol (PA). Tear samples were collected using 1 μl glass capillaries at recruitment into the study and after a 3-week treatment period, both before and after 2 h exposure to desiccating stress, in a controlled environment chamber...
September 13, 2017: Ocular Surface
https://www.readbyqxmd.com/read/28917861/isolation-and-structural-elucidation-by-2d-nmr-of-planteose-a-major-oligosaccharide-in-the-mucilage-of-chia-salvia-hispanica-l-seeds
#9
Xiaohui Xing, Yves S Y Hsieh, Kuok Yap, Main E Ang, Jelle Lahnstein, Matthew R Tucker, Rachel A Burton, Vincent Bulone
An oligosaccharide was isolated in high purity and excellent yield from the water-extractable mucilage of chia (Salvia hispanica L.) seeds using an optimized solid-phase extraction method. LC-MS analysis showed that the compound presents a molecular mass of 504Da and trifluoroacetic acid hydrolysis revealed that it consists of galactose, glucose and fructose. Glycosidic linkage analysis showed that the oligosaccharide contains two non-reducing ends corresponding to terminal glucopyranose and terminal galactopyranose, respectively...
November 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28917820/characterization-of-secondary-organic-aerosol-from-photo-oxidation-of-gasoline-exhaust-and-specific-sources-of-major-components
#10
Pengkun Ma, Peng Zhang, Jinian Shu, Bo Yang, Haixu Zhang
To further explore the composition and distribution of secondary organic aerosol (SOA) components from the photo-oxidation of light aromatic precursors (toluene, m-xylene, and 1,3,5-trimethylbenzene (1,3,5-TMB)) and idling gasoline exhaust, a vacuum ultraviolet photoionization mass spectrometer (VUV-PIMS) was employed. Peaks of the molecular ions of the SOA components with minimum molecular fragmentation were clearly observed from the mass spectra of SOA, through the application of soft ionization methods in VUV-PIMS...
September 13, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28917730/direct-and-comprehensive-analysis-of-dyes-based-on-integrated-molecular-and-structural-information-via-laser-desorption-laser-postionization-mass-spectrometry
#11
Rong Liu, Zhibin Yin, Yixin Leng, Wei Hang, Benli Huang
Laser desorption laser postionization time-of-flight mass spectrometry (LDPI-TOFMS) was employed for direct analysis and determination of typical basic dyes. It was also used for the analysis and comprehensive understanding of complex materials such as blue ballpoint pen inks. Simultaneous emergences of fragmental and molecular information largely simplify and facilitate unambiguous identification of dyes via variable energy of 266nm postionization laser. More specifically, by optimizing postionization laser energy with the same energy of desorption laser, the structurally significant results show definite differences in the fragmentation patterns, which offer opportunities for discrimination of isomeric species with identical molecular weight...
January 1, 2018: Talanta
https://www.readbyqxmd.com/read/28917163/raman-and-fourier-transform-infrared-spectroscopic-study-of-pyromorphite-vanadinite-solid-solutions
#12
Urszula Solecka, Tomasz Bajda, Justyna Topolska, Sylwia Zelek-Pogudz, Maciej Manecki
Due to the great range of the application fields for apatites, there is a strong need to complete the data set determining the properties of these minerals. In this study, Raman and Infrared spectra of the phases from pyromorphite Pb5(PO4)3Cl - vanadinite Pb5(VO4)3Cl series were investigated. Totally, 9 samples (2 end-members and 7 solid solutions of the series) were synthesized at 25°C and pH=3.5, and analyzed. In the Raman and Infrared spectra of the studied Pb-apatites, the bands typical for the vibrations in the PO4 and the VO4 tetrahedra appeared...
August 26, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28915941/paper-spray-and-kendrick-mass-defect-analysis-of-block-and-random-ethylene-oxide-propylene-oxide-copolymers
#13
Robert B Cody, Thierry Fouquet
Paper spray ionization coupled with a high-resolution time-of-flight mass spectrometer was applied to the analysis of 13 block and 2 random ethylene oxide/propylene oxide (EO/PO) copolymers as well as to standard samples of poly(ethylene oxide) and poly(propylene oxide) homopolymers. Paper spray mass spectra could be obtained rapidly and, unlike electrospray ionization, were not subject to contamination and sample carryover. For comparison, polyether samples were also measured on a MALDI/TOF system with ultrahigh mass resolving power...
October 9, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28913531/augmented-ph-sensitivity-absorbance-of-a-ruthenium-ii-bis-bipyridine-complex-with-elongation-of-the-conjugated-ligands-an-experimental-and-theoretical-investigation
#14
Siew San Tan, Susumu Yanagisawa, Kouji Inagaki, Yoshitada Morikawa, Mohammad B Kassim
An absorbance-based sensor employing ruthenium bipyridyl with a phenanthroline-fused benzoylthiourea moiety formulated as [Ru(ii)(bpy)2(phen-nBT)](PF6)2 {bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline, nBT = n-benzoylthiourea} has been synthesized and characterized by elemental analyses, mass spectrometry, and infrared, ultraviolet-visible, luminescence and nuclear magnetic resonance spectroscopy. The changes in the intensity of absorption and emission of the complex induced by functionalization of the benzoylthiourea ligands with amino and carbonyl in their protonated and deprotonated forms were studied experimentally...
September 15, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28912556/synthesis-and-in-vitro-anticancer-evaluation-of-polyarsenicals-related-to-the-marine-sponge-derived-arsenicin-a
#15
Ines Mancini, Matteo Planchestainer, Andrea Defant
In the light of the promising bioactivity of the tetraarsenic marine metabolite arsenicin A, the dimethyl analogue 2 and four isomeric methylene homologues (including the natural product itself) were obtained using a one-pot microwave-assisted synthesis, starting from arsenic (III) oxide. Due to the poor diagnostic value of the NMR technique in the structural elucidation of these molecules, they were fully characterized by mass spectrometry and infrared (IR)-spectroscopy, comparing density functional theory (DFT) simulated and experimental spectra...
September 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28911769/measurement-of-kinetic-isotope-effects-in-an-enzyme-catalyzed-reaction-by-continuous-flow-mass-spectrometry
#16
Kenneth M Roberts, Paul F Fitzpatrick
Kinetic isotope effects (KIEs) provide powerful probes of the mechanisms of enzyme-catalyzed reactions. In this chapter, we describe the use of continuous-flow mass spectrometry to determine the deuterium KIE for the enzyme N-acetylpolyamine oxidase based on the ratio of labeled and unlabeled products in mass spectra of whole reaction mixtures.
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28911652/microbiological-histological-and-biochemical-evidence-for-the-adverse-effects-of-food-azo-dyes-on-rats
#17
Khaled Elbanna, Osama Mohamed Sarhan, Manal Khider, Mohamed Elmogy, Hussein Hasan Abulreesh, Mohamed Rabie Shaaban
In this study, 120 lactic acid bacterial strains from different fermented dairy products as well as 10 bacterial intestinal isolates were evaluated for in vitro and in vivo degradation of various food azo dyes. Of these isolates, lactic acid bacteria (LAB) strains 13 and 100 and the intestinal isolates Ent2 and Eco5 exhibited 96-98% degradation of the tested food azo dyes within 5-6 hours. High performance liquid chromatography mass spectra of sunset yellow (E110) and carmoisine (E122) anaerobic degradation products by the intestinal isolates showed that they were structurally related to toxic aromatic amines...
July 2017: Journal of Food and Drug Analysis
https://www.readbyqxmd.com/read/28911223/direct-sampling-and-analysis-of-atmospheric-particulate-organic-matter-by-proton-transfer-reaction-mass-spectrometry
#18
Markus Muller, Philipp Eichler, Barbara D'Anna, Wen Tan, Armin Wisthaler
We report on a new method for analyzing atmospheric submicrometer particulate organic matter which combines direct particle sampling and volatilization with on-line chemical ionization mass spectrometric analysis. Technically, the method relies on the combined use of a CHARON ("Chemical Analysis of Aerosol On-line") particle inlet and a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS). Laboratory studies on target analytes showed that the ionization conditions in the PTR-ToF-MS lead to extensive fragmentation of levoglucosan and cis-pinonic acid, while protonated oleic acid and 5-cholestane molecules remain intact...
September 15, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28906013/novel-insights-into-the-inhibitory-effect-and-mechanism-of-proanthocyanidins-from-pyracantha-fortuneana-fruit-on-%C3%AE-glucosidase
#19
Mankun Wei, Wei-Ming Chai, Qin Yang, Rui Wang, Yiyuan Peng
Proanthocyanidins were extracted from Pyracantha fortuneana fruit (PFF), and their structures were investigated through (13) C nuclear magnetic resonance ((13) C NMR), high performance liquid chromatography (HPLC) and high resolution mass spectrometry (HRMS). The results showed that these compounds were predominantly constituted of procyanidin with A-type and B-type linkage and coexistence of procyanidins glucoside. Spectroscopy methods were used to analyze the inhibitory activity of proanthocyanidins on α-glucosidase...
September 14, 2017: Journal of Food Science
https://www.readbyqxmd.com/read/28905148/building-a-pgc-lc-ms-n-glycan-retention-library-and-elution-mapping-resource
#20
Jodie L Abrahams, Matthew P Campbell, Nicolle H Packer
Porous graphitised carbon-liquid chromatography (PGC-LC) has been proven to be a powerful technique for the analysis and characterisation of complex mixtures of isomeric and isobaric glycan structures. Here we evaluate the elution behaviour of N-glycans on PGC-LC and thereby provide the potential of using chromatographic separation properties, together with mass spectrometry (MS) fragmentation, to determine glycan structure assignments more easily. We used previously reported N-glycan structures released from the purified glycoproteins Immunoglobulin G (IgG), Immunoglobulin A (IgA), lactoferrin, α1-acid glycoprotein, Ribonuclease B (RNase B), fetuin and ovalbumin to profile their behaviour on capillary PGC-LC-MS...
September 13, 2017: Glycoconjugate Journal
keyword
keyword
86994
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"