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https://www.readbyqxmd.com/read/29331144/communication-site-selective-bond-excision-of-adenine-upon-electron-transfer
#1
T Cunha, M Mendes, F Ferreira da Silva, S Eden, G García, P Limão-Vieira
This work demonstrates that selective excision of hydrogen atoms at a particular site of the DNA base adenine can be achieved in collisions with electronegative atoms by controlling the impact energy. The result is based on analysing the time-of-flight mass spectra yields of potassium collisions with a series of labeled adenine derivatives. The production of dehydrogenated parent anions is consistent with neutral H loss either from selective breaking of C-H or N-H bonds. These unprecedented results open up a new methodology in charge transfer collisions that can initiate selective reactivity as a key process in chemical reactions that are dominant in different areas of science and technology...
January 14, 2018: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29329347/salivary-proteomics-of-healthy-dogs-an-in-depth-catalog
#2
Sheila M F Torres, Eva Furrow, Clarissa P Souza, Jennifer L Granick, Ebbing P de Jong, Timothy J Griffin, Xiong Wang
OBJECTIVE: To provide an in-depth catalog of the salivary proteome and endogenous peptidome of healthy dogs, evaluate proteins and peptides with antimicrobial properties, and compare the most common salivary proteins and peptides between different breed phylogeny groups. METHODS: 36 healthy dogs without evidence of periodontal disease representing four breed phylogeny groups, based upon single nucleotide polymorphism haplotypes (ancient, herding/sighthound, and two miscellaneous groups)...
2018: PloS One
https://www.readbyqxmd.com/read/29328982/systematic-identification-of-suspected-anthelmintic-benzimidazole-metabolites-using-lc-ms-ms
#3
Marius Majewsky, David Castel, Ludivine Le Dret, Pascal Johann, David T Jones, Stefan M Pfister, Walter E Haefeli, Jürgen Burhenne
Metabolite reference standards are often not available, which results in a lack of MS/MS spectra for library matching. Consequently, the identification of suspected metabolites proves to be challenging. The present study aims at structurally elucidating the MS/MS fragmentation behavior of selected benzimidazole anthelmintics to theoretically predict characteristic product ions for rapid and systematic tentative metabolite identification. A set of common characteristic product ions was identified from accurate mass MS/MS experiments for five parent compounds...
December 28, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/29328543/the-sarda-sheep-host-fecal-proteome
#4
Antonio Palomba, Alessandro Tanca, Maria Filippa Addis, Daniela Pagnozzi, Sergio Uzzau
We recently reported the first characterization of the sheep fecal microbiota, obtained by using a multi-meta-omic approach. Here, the mass spectra generated by single-run LC/high-resolution MS in the context of that study were reanalyzed using a host-specific database, in order to gain insights for the first time into the host fecal proteome of healthy Sarda sheep. On the whole, 5349 non-redundant tryptic peptide sequences were identified, belonging to 1046 different proteins. The "core" fecal proteome (common to all animals) comprised 431 proteins, mainly related to biological processes as immune response and proteolysis...
January 12, 2018: Proteomics
https://www.readbyqxmd.com/read/29328060/-i-in-vivo-i-neutron-activation-analysis-of-bone-manganese-in-workers
#5
Yingzi Liu, Danelle Rolle-McFarland, Farshad Mostafaei, Yuanzhong Zhou, Yan Li, Wei Zheng, Ellen Wells, Linda Huiling Nie
Manganese (Mn) is a neurotoxicant. However, the impact of elevated, chronic Mn exposure is not well understood, partially due to the lack of a cumulative exposure biomarker. To address this gap, our group developed a compact <i>in vivo</i> neutron activation analysis (IVNAA) system to quantify Mn in bone (MnBn). In this study, we used this system and determined MnBn among male Chinese workers and compared results to their blood Mn (MnB), a measure of recent exposure, and the years of employment, a measure of cumulative exposure...
January 12, 2018: Physiological Measurement
https://www.readbyqxmd.com/read/29327814/systematic-evaluation-of-protein-sequence-filtering-algorithms-for-proteoform-identification-using-top-down-mass-spectrometry
#6
Qiang Kou, Si Wu, Xiaowen Liu
Complex proteoforms contain various primary structural alterations resulting from variations in genes, RNA, and proteins. Top-down mass spectrometry is commonly used for analyzing complex proteoforms because it provides whole sequence information of the proteoforms. Proteoform identification by top-down mass spectral database search is a challenging computational problem because the types and/or locations of some alterations in target proteoforms are in general unknown. Although spectral alignment and mass graph alignment algorithms have been proposed for identifying proteoforms with unknown alterations, they are extremely slow to align millions of spectra against tens of thousand protein sequences in high throughput proteome level analyses...
January 12, 2018: Proteomics
https://www.readbyqxmd.com/read/29327507/rapid-characterization-of-chlorogenic-acids-in-duhaldea-nervosa-based-on-uhplc-ltq-orbitrap-ms-and-mass-spectral-trees-similarity-filter-technique
#7
Lianghong Liu, Jiayu Zhang, Binjie Zheng, Ying Guan, Liting Wang, Lei Chen, Wei Cai
Duhaldea nervosa (Wallich ex Candolle) A. Anderberg (D. nervosa) has been traditionally used as a food spice and also in folk medicine for treating traumatic injury and relieving rheumatism, especially, accelerating the healing of a fracture. However, so far as we are aware, the chemical constituents have not been fully investigated. In this study, a practical method of mass spectral trees similarity filter, a data-mining technique, was developed and evaluated for the rapid detection and identification complicated constituents based on UHPLC-LTQ-Orbitrap-MS...
January 12, 2018: Journal of Separation Science
https://www.readbyqxmd.com/read/29327411/reductive-alkaline-release-of-n-glycans-generates-a-variety-of-unexpected-useful-products
#8
Rudolf Figl, Friedrich Altmann
Release of O-glycans by reductive β-elimination has become routine in many glyco-analytical laboratories and concomitant release of N-glycans has repeatedly been observed. Revisiting this somewhat forgotten mode of N-glycan release revealed that all kinds of N-glycans including oligomannosidic and complex-type N-glycans from plants with 3-linked fucose and from mammals with or without 6-linked fucose and with sialic acid could be recovered. However, the mass spectra of the obtained products revealed very surprising facts...
January 12, 2018: Proteomics
https://www.readbyqxmd.com/read/29325003/reversible-colour-change-in-leaves-enhances-pollinator-attraction-and-reproductive-success-in-saururus-chinensis-saururaceae
#9
Bo Song, Jürg Stöcklin, W Scott Armbruster, Yongqian Gao, Deli Peng, Hang Sun
Background and Aims: Although there has been much experimental work on leaf colour change associated with selection generated by abiotic environmental factors and antagonists, the role of leaf colour change in pollinator attraction has been largely ignored. We tested whether whitening of the apical leaves subtending the inflorescences of Saururus chinensis during flowering enhances pollinator attraction, and whether re-greening of the white leaves after flowering increases carbon assimilation and promotes seed development...
January 9, 2018: Annals of Botany
https://www.readbyqxmd.com/read/29323663/multiplexed-proteome-analysis-with-neutron-encoded-stable-isotope-labeling-in-cells-and-mice
#10
Katherine A Overmyer, Stefka Tyanova, Alex S Hebert, Michael S Westphall, Jürgen Cox, Joshua J Coon
We describe a protocol for multiplexed proteomic analysis using neutron-encoded (NeuCode) stable isotope labeling of amino acids in cells (SILAC) or mice (SILAM). This method currently enables simultaneous comparison of up to nine treatment and control proteomes. Another important advantage over traditional SILAC/SILAM is that shorter labeling times are required. Exploiting the small mass differences that correspond to subtle differences in the neutron-binding energies of different isotopes, the amino acids used in NeuCode SILAC/SILAM differ in mass by just a few milliDaltons...
January 2018: Nature Protocols
https://www.readbyqxmd.com/read/29323292/bright-triplet-excitons-in-caesium-lead-halide-perovskites
#11
Michael A Becker, Roman Vaxenburg, Georgian Nedelcu, Peter C Sercel, Andrew Shabaev, Michael J Mehl, John G Michopoulos, Samuel G Lambrakos, Noam Bernstein, John L Lyons, Thilo Stöferle, Rainer F Mahrt, Maksym V Kovalenko, David J Norris, Gabriele Rainò, Alexander L Efros
Nanostructured semiconductors emit light from electronic states known as excitons. For organic materials, Hund's rules state that the lowest-energy exciton is a poorly emitting triplet state. For inorganic semiconductors, similar rules predict an analogue of this triplet state known as the 'dark exciton'. Because dark excitons release photons slowly, hindering emission from inorganic nanostructures, materials that disobey these rules have been sought. However, despite considerable experimental and theoretical efforts, no inorganic semiconductors have been identified in which the lowest exciton is bright...
January 10, 2018: Nature
https://www.readbyqxmd.com/read/29319709/displacement-of-%C3%AE-5-cyclopentadienyl-ligands-from-half-sandwich-c-c-nhc-cyanoalkyl-nickel-ii-metallacycles-further-insight-into-the-structure-of-the-resulting-cp-free-nickelacycles-and-a-catalytic-activity-study
#12
Bernardo de P Cardoso, Jean-Marie Bernard-Schaaf, Saurabh Shahane, Luis F Veiros, Michael J Chetcuti, Vincent Ritleng
Four cationic C,C-(NHC-cyanoalkyl)-nickel(ii) metallacyclic complexes, [Ni{Me-NHC-CH2CH(CN)}(NCMe)](PF6) (2a), [Ni{Mes-NHC-CH2CH(CN)}(NCMe)](PF6) (2b), [Ni{Mes-NHC-(CH2)2CH(CN)}(NCMe)](PF6) (2c) and [Ni{DiPP-NHC-(CH2)2CH(CN)}(NCMe)](PF6) (2d), were prepared by the removal of the Cp ligand under acidic conditions at 0 °C from the corresponding half-sandwich nickelacycles [NiCp{R-NHC-(CH2)nCH(CN)}] (1a-1d; Cp = η5-C5H5; n = 1 or 2; R-NHC-(CH2)nCH(CN) = 1-R-3-[(CH2)nCH(CN)]-imidazol-2-ylidene). Full characterization of 2a-d by 1H and 13C{1H} NMR spectroscopy in CD3CN and pyridine-d5, ATR-FTIR spectroscopy, mass spectrometry, and CHN microanalyses established the presence of only one acetonitrile ligand per nickel atom in the solid state...
January 10, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29318295/reaction-monitoring-by-means-of-multivariate-data-analysis-of-near-infrared-and-raman-spectra
#13
Dardan Hetemi, Steve Janagap
An efficient, versatile and non-destructive in situ method in reaction monitoring using vibrational spectroscopy is described. A Suzuki cross-coupling reaction was monitored in which the substrate 1-iodo-2-nitrobenzene reacted with the electrophile phenylboronic acid to form the product 2-nitrobiphenyl. To hasten the reaction, palladium(II) acetate and potassium carbonate were added to serve as catalyst and to promote transmetalation, respectively. This reaction was monitored using near-infrared and Raman spectroscopy...
December 2017: Acta Chimica Slovenica
https://www.readbyqxmd.com/read/29316281/hplc-ms-ms-determination-of-flavonoids-in-gleditsiae-spina-for-its-quality-assessment
#14
Jing Li, Kun Jiang, Li-Jun Wang, Guo Yin, Jue Wang, Yang Wang, Yi-Bao Jin, Qing Li, Tie-Jie Wang
Gleditsiae Spina, the thorn of Gleditsia sinensis Lam., has been used as an anti-inflammatory, anti-tumor, and anti-bacterial traditional medicine for hundreds of years in China. This study used high-performance liquid chromatography and tandem mass spectrometry combined with chemometric methods to allow the fast and accurate identification and quantification of the flavonoids compounds in Gleditsiae Spina, and created reliable criteria for accurate identification of Gleditsiae Spina and its adulterants. This research provides good evidence for the classification and quality evaluation of Gleditsiae Spina...
January 5, 2018: Journal of Separation Science
https://www.readbyqxmd.com/read/29316117/c8n26h4-an-environmentally-friendly-primary-explosive-with-high-heat-of-formation
#15
Dan Chen, Hongwei Yang, Zhenxin Yi, Hualin Xiong, Lin Zhang, Shunguan Zhu, Guangbin Cheng
This study presents the synthesis and characterization of the new metal-free polyazido compounds 3,6-bis-(2-(4,6-diazido-1,3,5-triazin-2-yl)-hydrazinyl)-1,2,4,5-tetrazine (2) and 3,6-bis-(2-(4,6-diazido-1,3,5-triazin-2-yl)-diazenyl)-1,2,4,5-tetrazine (4). Two compounds were characterized by NMR spectra, IR spectroscopy, mass spectrometry, and differential scanning calorimetry (DSC). Additionally, the structure of title compound 2 was confirmed by single crystal X-ray diffraction. Compounds 2 and 4 exhibit measured densities (1...
January 8, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29314750/phase-i-metabolism-of-the-recently-emerged-synthetic-cannabinoid-cumyl-pegaclone-and-detection-in-human-urine-samples
#16
Lukas Mogler, Maurice Wilde, Laura M Huppertz, Georg Weinfurtner, Florian Franz, Volker Auwärter
Indole, indazole or azaindole based synthetic cannabinoids (SCs), bearing a cumyl substituent are a widespread, recreationally used subgroup of new psychoactive substances (NPS). The latest cumyl-derivative, CUMYL-PEGACLONE, emerged in December 2016 on the German drug market. The substance features a novel γ-carboline core structure, which is most likely synthesized to bypass generic legislative approaches to control SCs by prohibiting distinct core structures. Using liquid chromatography tandem mass spectrometry and liquid chromatography high resolution mass spectrometry techniques, the main in vivo phase I metabolites of this new substance were detected...
January 3, 2018: Drug Testing and Analysis
https://www.readbyqxmd.com/read/29314679/molecular-epidemiology-of-trichophyton-quinckeanum-a-zoophilic-dermatophyte-on-the-rise
#17
Silke Uhrlaß, Wieland Schroedl, Carolin Mehlhorn, Constanze Krüger, Vit Hubka, Thomas Maier, Yvonne Gräser, Uwe Paasch, Pietro Nenoff
BACKGROUND: Formerly only referred to as a subspecies (T. mentagrophytes var. quinckeanum), T. quinckeanum once again constitutes a distinct species according to the updated taxonomy of dermatophytes. PATIENTS AND METHODS: During routine diagnostic tests conducted at the Mycology Laboratory, Mölbis, Germany, between 11/2013 to 1/2017 (three years and three months), all specimens sent in were examined for T. quinckeanum. Molecular biology methods employed included: 1) DNA hybridization (PCR ELISA), 2) gene sequencing of the ITS region and TEF-1α, and 3) in some cases, MALDI-TOF mass spectrometry...
January 2018: Journal der Deutschen Dermatologischen Gesellschaft, Journal of the German Society of Dermatology: JDDG
https://www.readbyqxmd.com/read/29313358/two-new-tricycloalternarene-esters-from-an-alga-epiphytic-isolate-of-alternaria-alternata
#18
Zhen-Zhen Shi, Sheng-Tao Fang, Feng-Ping Miao, Nai-Yun Ji
Two new tricycloalternarene-type meroterpenes, 17-O-methyltricycloalternarene D (1) and methyl nortricycloalternarate (4), and two known congeners, TCA D (2) and TCA 1b (3), were isolated from the culture of a marine red alga-epiphytic fungal strain (k21-1) of Alternaria alternata. The planar structures and relative configurations of these two new compounds were unequivocally identified by a combination of 1D/2D NMR, UV, IR, and mass spectra and by comparison with literature data, and the absolute configurations were assigned by analysis of ECD spectra...
January 9, 2018: Natural Product Research
https://www.readbyqxmd.com/read/29313204/gas-phase-reactions-of-dimethyl-disulfide-with-aliphatic-carbanions-a-mass-spectrometry-and-computational-study
#19
Barbara Franczuk, Witold Danikiewicz
Ion-molecule reactions of Me2S2 with a wide range of aliphatic carbanions differing by structure and proton affinity values have been studied in the gas phase using mass spectrometry techniques and DFT calculations. The analysis of the spectra shows a variety of product ions formed via different reaction mechanisms, depending on the structure and proton affinity of the carbanion. Product ions of thiophilic reaction (m/z 47), SN2 (m/z 79), and E2 elimination - addition sequence of reactions (m/z 93) can be observed...
January 8, 2018: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/29310273/identification-and-classification-of-cathinone-unknowns-by-statistical-analysis-processing-of-direct-analysis-in-real-time-high-resolution-mass-spectrometry-derived-neutral-loss-spectra
#20
Kristen L Fowble, Jason R E Shepard, Rabi A Musah
An approach to the rapid determination of the structures of novel synthetic cathinone designer drugs, also known as bath salts, is reported. While cathinones fragment so extensively by electron impact mass spectrometry that their mass spectra often cannot be used to identify the structure, collision-induced dissociation (CID) direct analysis in real time-high resolution mass spectrometry (DART-HRMS) experiments furnished spectra that provided diagnostic fragmentation patterns for the analyzed cathinones. From this data, neutral loss spectra, which reflect the presence of specific chemical moieties, could be acquired...
March 1, 2018: Talanta
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