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Phosphoric acid

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https://www.readbyqxmd.com/read/29144587/characterization-of-complex-heterogeneous-lipid-a-samples-using-hplc-ms-ms-technique-iii-positive-ion-mode-tandem-mass-spectrometry-to-reveal-phosphorylation-and-acylation-patterns-of-lipid-a
#1
Viktor Sándor, Anikó Kilár, Ferenc Kilár, Béla Kocsis, Ágnes Dörnyei
In this study, we report the detailed analysis of the fragmentation patterns of positively charged lipid A species based on their tandem mass spectra obtained under low-energy collision-induced dissociation conditions of an electrospray quadrupole time-of-flight mass spectrometers. The tandem mass spectrometry experiments were performed after the separation of the compounds with a reversed-phase high performance liquid chromatography method. We found that both, phosphorylated and nonphosphorylated lipid A molecules can be readily ionized in the positive-ion mode by adduct formation with triethylamine added to the eluent...
November 16, 2017: Journal of Mass Spectrometry: JMS
https://www.readbyqxmd.com/read/29143263/enhanced-stabilization-of-pb-zn-and-cd-in-contaminated-soils-using-oxalic-acid-activated-phosphate-rocks
#2
Zhuo Zhang, Guanlin Guo, Mei Wang, Jia Zhang, Zhixin Wang, Fasheng Li, Honghan Chen
Phosphate amendments, especially phosphate rock (PR), are one of the most commonly used materials to stabilize heavy metals in contaminated soils. However, most of PR reserve consists of low-grade ore, which limits the efficiency of PR for stabilizing heavy metals. This study was to enhance the stabilization of heavy metals through improving the available phosphorous (P) release of PR by oxalic acid activation. Raw PR and activated PR (APR) were characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), X-ray powder diffraction (XRD), Brunauer-Emmett-Teller (BET) surface analysis, and laser diffraction to determine the changes of structure and composition of APR...
November 15, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/29140719/effects-of-different-etching-methods-and-bonding-procedures-on-shear-bond-strength-of-orthodontic-metal-brackets-applied-to-different-cad-cam-ceramic-materials
#3
S Kutalmış Buyuk, Ahmet Serkan Kucukekenci
OBJECTIVE: To investigate the shear bond strength (SBS) of orthodontic metal brackets applied to different types of ceramic surfaces treated with different etching procedures and bonding agents. MATERIALS AND METHODS: Monolithic CAD/CAM ceramic specimens (N = 120; n = 40 each group) of feldspathic ceramic Vita Mark II, resin nanoceramic Lava Ultimate, and hybrid ceramic Vita Enamic were fabricated (14 × 12 × 3 mm). Ceramic specimens were separated into four subgroups (n = 10) according to type of surface treatment and bonding onto the ceramic surface...
November 15, 2017: Angle Orthodontist
https://www.readbyqxmd.com/read/29136831/rapid-method-for-determination-of-90-sr-in-seawater-by-liquid-scintillation-counting-with-an-extractive-scintillator
#4
Masaki Uesugi, Ryosuke Watanabe, Hiroaki Sakai, Akihiko Yokoyama
A rapid determination method of (90)Sr is developed for the monitoring of seawater around the Fukushima Daiichi Nuclear Power Plant (FDNPP). Three ideas of chemical separation and measurements to accelerate (90)Sr analysis are investigated. Strontium is co-precipitated in a two-step procedure with hydroxyapatite after the removal of magnesium phosphate in the presence of citric acid. The purification process of strontium is in combination with solid phase extraction disks. One or two sheets of Sr Rad disk and cyclic operations are examined to eliminate interfering substances and secure the exchange capacity...
February 1, 2018: Talanta
https://www.readbyqxmd.com/read/29135464/polybenzimidazole-mxene-composite-membranes-for-intermediate-temperature-polymer-electrolyte-membrane-fuel-cells
#5
Mingming Fei, Ruizhi Lin, Yuming Deng, Hongxi Xian, Renji Bian, Xiaole Zhang, Jigui Cheng, Chenxi Xu, Dongyu Cai
This report demonstrated the first study on the use of a new 2D nanomaterial (Mxene) for enhancing membrane performance of intermediate temperature (>100 oC) polymer electrolyte membrane fuel cells (ITPEMFCs). In this study, a typical Ti3C2Tx-MXene was synthesized and incorporated into polybenzimidazole (PBI)-based membranes by using a solution blending method. The composite membrane with 3wt.% Ti3C2Tx-MXene showed the proton conductivity more than 2 times higher than that of pristine PBI membrane at the temperature range of 100-170 ºC, and led to substantial increase in maximum power density of fuel cells by ~ 30% tested at 150 oC...
November 14, 2017: Nanotechnology
https://www.readbyqxmd.com/read/29134292/simultaneous-determination-of-brazilin-and-protosappanin-b-in-caesalpinia-sappan-by-ionic-liquid-dispersive-liquid-phase-microextraction-method-combined-with-hplc
#6
Zhaoyang Xia, Dongdong Li, Qing Li, Yan Zhang, Wenyi Kang
The conditions of heating, ionic liquid-based ultrasonic-assisted extraction combined with reverse-phase high performance liquid chromatography were optimized to simultaneously isolate and determinate brazilin and protosappanin B in Caesalpinia sappan. Ionic liquids, including [BMIM]Br, [BMIM]BF4, [BMIM]PF6 and [HMIM]PF6, were selected as extraction solvents while methanol, acetone, acetonitrile, ethanol and water were selected as dispersants. The chromatographic column was Purospher star RP-C18 (250 mm × 4...
November 13, 2017: Chemistry Central Journal
https://www.readbyqxmd.com/read/29130300/psite-amino-acid-confidence-evaluation-for-quality-control-of-de-novo-peptide-sequencing-and-modification-site-localization
#7
Hao Yang, Hao Chi, Wen-Jing Zhou, Wen-Feng Zeng, Chao Liu, Rui-Min Wang, Zhao-Wei Wang, Xiu-Nan Niu, Zhen-Lin Chen, Si-Min He
MS-based de novo peptide sequencing has been improved remarkably with significant development of mass spectrometry and computational approaches, but still lacks quality control methods. Here we proposed a novel algorithm pSite to evaluate the confidence of each amino acid rather than the full-length peptides obtained by de novo peptide sequencing. A semi-supervised learning approach was used to discriminate correct amino acids from random ones and then an expectation-maximization algorithm was used to adaptively control the false amino-acid rate (FAR)...
November 13, 2017: Journal of Proteome Research
https://www.readbyqxmd.com/read/29126083/hplc-uv-ms-method-application-for-the-separation-of-obeticholic-acid-and-its-related-compounds-in-development-process-and-quality-control
#8
Michal Douša, Markéta Slavíková, Tomáš Kubelka, Josef Černý, Petr Gibala, Josef Zezula
An HPLC method with UV and electrospray ionization - mass spectrometry (ESI-MS) detection was developed for the separation and determination of obeticholic acid (OBE) and its related compounds in development process and quality control. OBE and its related compounds were classified into three major group based on the mass spectra profiles: (A) those containing a hydroxyl group at position 3 and 7, (B) those containing a hydroxyl group and/or carbonyl group at position 3, hydrogen, ethyl or ethylidene group at position 6 and a hydroxyl group and/or carbonyl group at position 7, and (C) those containing carbonyl groups at position 3 and 7...
November 4, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/29118646/epilithic-diatom-communities-of-selected-streams-from-the-lerma-chapala-basin-central-mexico-with-the-description-of-two-new-species
#9
Demetrio Mora, Javier Carmona, Regine Jahn, Jonas Zimmermann, Nélida Abarca
The Lerma-Chapala Basin, in Central Mexico, is geologically heterogeneous, climatically diverse and boasts high biodiversity, lying within two Biodiversity Hotspots, namely Mesoamerica and the Madrean Pine-Oak Woodlands. Epilithon and water samples were collected in the basin from 14 sampling sites three times each, two sampling campaigns during the rainy season and one in the dry season. A total of 274 infrageneric taxa in 48 genera were recorded. The taxonomic composition observed was dominated by taxa from the genera Nitzschia, Gomphonema, Pinnularia, Navicula, Sellaphora and Eunotia...
2017: PhytoKeys
https://www.readbyqxmd.com/read/29114326/phosphonic-acid-preparation-and-applications
#10
REVIEW
Charlotte M Sevrain, Mathieu Berchel, Hélène Couthon, Paul-Alain Jaffrès
The phosphonic acid functional group, which is characterized by a phosphorus atom bonded to three oxygen atoms (two hydroxy groups and one P=O double bond) and one carbon atom, is employed for many applications due to its structural analogy with the phosphate moiety or to its coordination or supramolecular properties. Phosphonic acids were used for their bioactive properties (drug, pro-drug), for bone targeting, for the design of supramolecular or hybrid materials, for the functionalization of surfaces, for analytical purposes, for medical imaging or as phosphoantigen...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29113047/improved-durability-and-sensitivity-of-bitterness-sensing-membrane-for-medicines
#11
Xiao Wu, Hideya Onitake, Zhiqin Huang, Takeshi Shiino, Yusuke Tahara, Rui Yatabe, Hidekazu Ikezaki, Kiyoshi Toko
This paper reports the improvement of a bitterness sensor based on a lipid polymer membrane consisting of phosphoric acid di-n-decyl ester (PADE) as a lipid and bis(1-butylpentyl) adipate (BBPA) and tributyl o-acetylcitrate (TBAC) as plasticizers. Although the commercialized bitterness sensor (BT0) has high sensitivity and selectivity to the bitterness of medicines, the sensor response gradually decreases to almost zero after two years at room temperature and humidity in a laboratory. To reveal the reason for the deterioration of the response, we investigated sensor membranes by measuring the membrane potential, contact angle, and adsorption amount, as well as by performing gas chromatography-mass spectrometry (GC-MS), liquid chromatography-tandem mass spectrometry (LC-MS/MS)...
November 4, 2017: Sensors
https://www.readbyqxmd.com/read/29112300/enantioselective-and-collective-total-syntheses-of-xanthanolides
#12
Yefeng Tang, Juan Feng, Xiaoqiang Lei, Ruiyang Bao, Yuanhe Li, Chengqian Xiao, Lihong Hu
An enantioselective synthesis of (+)-8-epi-xanthatin has been achieved, hinging on a chiral phosphoric acid-catalyzed tandem allylboration/lactonization reaction. With (+)-8-epi-xanthatin as precursor, the collective syntheses of a series of synthetically challenging xanthanolides were also accomplished. Among them, xanthipungolide, one of the most complicated xanthanolide monomers, was accessed through a bio-inspired tandem double bond isomerization/6π electronic cyclization/intramolecular Diels-Alder reaction, and pungiolides A, B, D, E, and L-N, a group of xanthanolide dimers, were assembled through a bio-inspired Diels-Alder dimerization followed by late-stage diversification...
November 7, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29111130/effect-of-sandblasting-and-enamel-deproteinization-on-shear-bond-strength-of-resin-modified-glass-ionomer
#13
Nadine Hamdane, Roland Kmeid, Elie Khoury, Joseph Ghoubril
INTRODUCTION: The purpose of this study was to compare, in vitro, the shear bond strength of resin-modified glass ionomer (RMGI) bonded to an enamel surface prepared by either sandblasting with 50μm of aluminium oxide particles, deproteinization with 5.25% NaOCl, or by combining both techniques. MATERIAL AND METHODS: One hundred and fifty human premolars were cleaned and randomly divided into five groups. In group 1, the teeth were etched using 37% phosphoric acid and bonded with Transbond XT...
October 27, 2017: International Orthodontics
https://www.readbyqxmd.com/read/29105896/practical-approach-to-axially-chiral-biaryl-amino-alcohols-via-organocatalytic-atroposelective-arylation-of-2-naphthylamines
#14
Bin Tan, Ye-Hui Chen, Liang-Wen Qi, Fang Fang
The first phosphoric acid-catalyzed direct arylation of 2-naphthylamines with iminoquinones for the atroposelective synthesis of axially chiral biaryl-amino-alcohols has been developed. This reaction features a highly functional group tolerant route to the rapid construction of enantioenriched axially chiral biaryl-amino-alcohols with good results. This represents a rare example of 2-naphthylamines acting as nucleophiles in organocatalytic enantioselective transformation. Furthermore, the products which have various halogen atoms offer access to structurally diverse axially chiral amino alcohols through further transformation...
November 5, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29103116/toward-new-benchmark-adsorbents-preparation-and-characterization-of-activated-carbon-from-argan-nut-shell-for-bisphenol-a-removal
#15
Mohamed Zbair, Kaisu Ainassaari, Asmaa Drif, Satu Ojala, Michael Bottlinger, Minna Pirilä, Riitta L Keiski, Mohammed Bensitel, Rachid Brahmi
The use of argan nut shell as a precursor for producing activated carbon was investigated in this work. Two activated carbons AC-HP and AC-Na were prepared from argan nut shell by chemical activation method using phosphoric acid (H3PO4) and sodium hydroxide (NaOH), respectively. Textural, morphological, and surface chemistry characteristics were studied by nitrogen physisorption, TGA, SEM, TXRF, FTIR, XRD, and by determining the pHPZC of the AC-HP. The adsorption experiments revealed that AC-HP was more efficient in adsorption of BPA due to high specific surface area (1372 m(2)/g) compared to AC-Na (798 m(2)/g)...
November 4, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/29100028/cleaning-verification-a-five-parameter-study-of-a-total-organic-carbon-method-development-and-validation-for-the-cleaning-assessment-of-residual-detergents-in-manufacturing-equipment
#16
Xue Li, Imad A Haidar Ahmad, James Tam, Yan Wang, Gina Dao, Andrei Blasko
A Total Organic Carbon (TOC) based analytical method to quantitate trace residues of clean-in-place (CIP) detergents CIP100(®) and CIP200(®) on the surfaces of pharmaceutical manufacturing equipment was developed and validated. Five factors affecting the development and validation of the method were identified: diluent composition, diluent volume, extraction method, location for TOC sample preparation, and oxidant flow rate. Key experimental parameters were optimized to minimize contamination and to improve the sensitivity, recovery, and reliability of the method...
October 26, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/29098858/transition-metal-phosphide-carbon-nanosheet-composites-derived-from-two-dimensional-metal-organic-frameworks-for-highly-efficient-electrocatalytic-water-splitting
#17
Mengke Zhai, Fei Wang, Hongbin Du
The preparation of highly active, sustainable, nonprecious metal materials as hydrogen evolution and oxygen evolution reaction (HER and OER) catalysts that can relieve the environmental pollution and energy shortage problems present a great challenge to chemists. We herein report the fabrication of a highly active metal phosphide-carbon composite catalyst for HER and OER in acid and basic solution, respectively. The catalyst is derived through carbonization and subsequent phosphorization of two-dimensional (2D) cobalt porphyrinic metal-organic framework nanosheets...
November 13, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29097126/sewage-sludge-as-a-fuel-and-raw-material-for-phosphorus-recovery-combined-process-of-gasification-and-p-extraction
#18
K Gorazda, B Tarko, S Werle, Z Wzorek
Increasing problems associated with sewage sludge disposal are observed nowadays. As the thermal conversion of sewage sludge (combustion, co-combustion, gasification and pyrolysis) appears to be the most promising alternative for its management, the solid residues left after gasification were examined. The present study evaluates the potential of this waste as an alternative phosphorus source in the context of phosphorus recovery. The obtained solid gasification residues were characterised (chemical and phase composition, thermal properties, surface properties and technological parameters used for phosphorus raw materials) and compared to commercial phosphate raw materials...
October 30, 2017: Waste Management
https://www.readbyqxmd.com/read/29096153/uptake-and-speciation-of-uranium-in-synthetic-gypsum-caso4%C3%A2-2h2o-applications-to-radioactive-mine-tailings
#19
Jinru Lin, Wei Sun, Jacques Desmarais, Ning Chen, Renfei Feng, Patrick Zhang, Dien Li, Arthur Lieu, John S Tse, Yuanming Pan
Phosphogypsum formed from the production of phosphoric acid represents by far the biggest accumulation of gypsum-rich wastes in the world and commonly contains elevated radionuclides, including uranium, as well as other heavy metals and metalloids. Therefore, billions-of-tons of phosphogypsum stockpiled worldwide not only possess serious environmental problems but also represent a potential uranium resource. Gypsum is also a major solid constituent in many other types of radioactive mine tailings, which stems from the common usage of sulfuric acid in extraction processes...
October 26, 2017: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/29094470/fabrication-of-nitrogen-and-phosphorous-doped-carbon-dots-by-the-pyrolysis-method-for-iodide-and-iron-iii-sensing
#20
Soumen Chandra, Angshuman Ray Chowdhuri, Dipranjan Laha, Sumanta Kumar Sahu
A facile and novel strategy to synthesize nitrogen- and phosphorous-doped carbon dots (NPCDs) by single step pyrolysis method is described here. Citric acid is used as carbon source and di-ammonium hydrogen phosphate is used as both nitrogen and phosphorous sources, respectively. Through the extensive study on optical properties, morphology and chemical structures of the synthesized NPCDs, it is found that as-synthesized NPCDs exhibited good excitation-dependent luminescence property, spherical morphology and high stability...
November 2, 2017: Luminescence: the Journal of Biological and Chemical Luminescence
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