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Phosphoric acid

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https://www.readbyqxmd.com/read/28812080/computational-design-of-ph-switchable-control-agents-for-nitroxide-mediated-polymerization
#1
Ganna Gryn'ova, Leesa M Smith, Michelle L Coote
In the present work we use accurate quantum chemistry to evaluate several known and novel nitroxides bearing acid-base groups as pH-switchable control agents for room temperature NMP. Based on G3(MP2,CC)(+)//M06-2X/6-31+G(d) calculations with UAKS-CPCM/M06-2X/6-31+G(d) solvation corrections, a number of novel nitroxides are predicted to be suitable for controlled polymerization of bulk styrene at room temperature when deprotonated (i.e. negatively charged), while remaining inert when neutral. These include an α-ethyl analogue of 3-carboxy-PROXYL and novel derivatives of 2,2,5-trimethyl-4-phenyl-3-azahexane-3-nitroxide (TIPNO) that have been modified to include acidic groups...
August 16, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28809551/direct-speciation-analysis-of-arsenic-in-whole-blood-and-blood-plasma-at-low-exposure-levels-by-hydride-generation-cryotrapping-inductively-coupled-plasma-mass-spectrometry
#2
Tomáš Matoušek, Zhifeng Wang, Christelle Douillet, Stanislav Musil, Miroslav Stýblo
A method for analysis of toxicologically important arsenic species in blood plasma and whole blood by selective hydride generation with cryotrapping (HG-CT) coupled either to atomic absorption (AAS) with a quartz multiatomizer or to inductively coupled plasma mass spectrometry (ICP-MS) has been validated. Sample preparation which involved only 5 times dilution with addition of Triton X-100, Antifoam B and L-cysteine suppressed excessive foaming in a hydride generator. Calibration slopes for whole blood and blood plasma spiked with arsenate, monomethylarsonate and dimethylarsinate at 0...
August 15, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28809505/relay-catalysis-manganese-iii-phosphate-catalyzed-asymmetric-addition-of-%C3%AE-dicarbonyls-to-ortho-quinone-methides-generated-by-catalytic-aerobic-oxidation
#3
Konrad Gebauer, Franziska Reuß, Matthias Spanka, Christoph Schneider
The combination of an in situ formed MnL3 complex (HL = Hacac or R(C═O)CH2CO2R) and a chiral phosphoric acid HX* allows for a fully catalytic, asymmetric synthesis of 4H-chromenes starting from 2-alkyl-substituted phenols. The aerobic oxidation toward a transient ortho-quinone methide was efficiently catalyzed by a manganese(III) species MnL3 while the ensuing Michael addition of β-dicarbonyl compounds proved to be catalyzed by a chiral manganese phosphate MnL2X*.
August 15, 2017: Organic Letters
https://www.readbyqxmd.com/read/28809050/versatile-chromatographic-method-for-catechin-determination-in-development-of-topical-formulations-containing-natural-extracts
#4
Ricardo Ferreira-Nunes, Tamara Angelo, Sandra Márcia Mazutti da Silva, Pérola Oliveira Magalhães, Tais Gratieri, Marcílio Sérgio Soares da Cunha-Filho, Guilherme Martins Gelfuso
Catechin is found in several natural sources, as Eugenia dysenterica and Syzygium cumini extracts. Its antioxidant and UV-protective properties suggest a potential use in cosmetic and dermatological formulations. A simple analytical method capable of giving support to experiments performed along the development of topical formulations containing this natural substance (i.e., drug assay, skin permeation and stability studies), however, is still demanded. Thus, this work aimed to develop and validate a selective HPLC method for catechin determination during the development of topical formulations...
August 15, 2017: Biomedical Chromatography: BMC
https://www.readbyqxmd.com/read/28803381/effect-of-soil-ph-and-organic-matter-on-the-adsorption-and-desorption-of-pentachlorophenol
#5
Shui-Wen Chang Chien, Shou-Hung Chen, Chi-Jui Li
Various properties of soil affect the partition of organic contaminants within, and conversely, the properties of the organic contaminants also directly affect their partition behavior in soil. Therefore, understanding the effects of various properties of soil on the partition of organic contaminants favors subsequent assessment and provides soil remediation methods for policymakers. This study selected pentachlorophenol (PCP), a common hydrophobic ionizable organic compound in contaminated sites worldwide, as the target contaminant...
August 12, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28795167/effective-uv-ozone-irradiation-method-for-decontamination-of-hydroxyapatite-surfaces
#6
Keisuke Yasuda, Yohei Okazaki, Yasuhiko Abe, Kazuhiro Tsuga
The purpose of this study was to establish whether UV/ozone (O3) irradiation method can effectively decontaminate hydroxyapatite surfaces, including those modified by the treatment with 30% phosphoric acid solution through morphological and chemical surface analyses (surface roughness, X-ray photoelectron spectroscopy and wettability), and to evaluate the in vitro response of osteoblast-like MC3T3-E1 cells to the modified hydroxyapatite surface decontaminated via this method. The amount of carbon and the contact angle of hydroxyapatite surfaces were significantly decreased by UV/O3 irradiation that lasted for ≥ 5 and ≥ 3 min, respectively (P < 0...
August 2017: Heliyon
https://www.readbyqxmd.com/read/28781907/development-and-validation-of-a-stability-indicating-hplc-method-for-the-simultaneous-determination-of-florfenicol-and-flunixin-meglumine-combination-in-an-injectable-solution
#7
Nidal Batrawi, Hani Naseef, Fuad Al-Rimawi
The combination of the powerful antimicrobial agent florfenicol and the nonsteroidal anti-inflammatory flunixin meglumine is used for the treatment of bovine respiratory disease (BRD) and control of BRD-associated pyrexia, in beef and nonlactating dairy cattle. This study describes the development and validation of an HPLC-UV method for the simultaneous determination of florfenicol and flunixin, in an injectable preparation with a mixture of excipients. The proposed RP-HPLC method was developed by a reversed phase- (RP-) C18e (250 mm × 4...
2017: Journal of Analytical Methods in Chemistry
https://www.readbyqxmd.com/read/28779896/enhanced-adsorption-of-cu-ii-and-cd-ii-by-phosphoric-acid-modified-biochars
#8
Hongbo Peng, Peng Gao, Gang Chu, Bo Pan, Jinhui Peng, Baoshan Xing
In this research, adsorption of Cu(II) and Cd(II) by biochars was investigated. To enhance the adsorption of these two metal ions, a simple modification of biochars by phosphoric acid (H3PO4) was carried out. The surface area was larger and the contents of oxygen-containing functional groups of modified biochars were more than pristine biochars. In comparison with pristine biochar, modified biochars sorbed Cu(II) and Cd(II) much more strongly. Surface area had significant effects on the sorption of Cu(II) and Cd(II) by modified biochars, it also resulted in the higher sorption for the pristine biochar at high pyrolysis temperature...
August 2, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28779890/effect-of-conditioning-solutions-containing-ferric-chloride-on-dentin-bond-strength-and-collagen-degradation
#9
Raquel Viana Rodrigues, Marcelo Giannini, Fernanda Miori Pascon, Preety Panwar, Dieter Brömme, Adriana Pigozzo Manso, Ricardo Marins Carvalho
OBJECTIVE: To investigate the effects of conditioning solutions containing ferric chloride (FeCl3) on resin-dentin bond strength; on protection of dentin collagen against enzymatic degradation and on cathepsin-K (CT-K) activity. METHODS: Conditioning solutions were prepared combining citric acid (CA) and anhydrous ferric chloride (FeCl3) in different concentrations. The solutions were applied to etch flat dentin surfaces followed by bonding with adhesive resin. Phosphoric acid (PA) gel etchant was used as control...
August 2, 2017: Dental Materials: Official Publication of the Academy of Dental Materials
https://www.readbyqxmd.com/read/28775296/transition-metal-alloying-effect-on-the-phosphoric-acid-adsorption-strength-of-pt-nanoparticles-an-experimental-and-density-functional-theory-study
#10
Hee-Young Park, Dong-Hee Lim, Sung Jong Yoo, Hyoung-Juhn Kim, Dirk Henkensmeier, Jin Young Kim, Hyung Chul Ham, Jong Hyun Jang
The effect of alloying with transition metals (Ni, Co, Fe) on the adsorption strength of phosphoric acid on Pt alloy surfaces was investigated using electrochemical analysis and first-principles calculations. Cyclic voltammograms of carbon-supported Pt3M/C (M = Ni, Co, and Fe) electrocatalysts in 0.1 M HClO4 with and without 0.01 M H3PO4 revealed that the phosphoric acid adsorption charge density near the onset potential on the nanoparticle surfaces was decreased by alloying with transition metals in the order Co, Fe, Ni...
August 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28774638/mangrove-endophyte-promotes-reforestation-tree-acacia-polyphylla-growth
#11
Renata Assis Castro, Manuella Nóbrega Dourado, Jaqueline Raquel de Almeida, Paulo Teixeira Lacava, André Nave, Itamar Soares de Melo, João Lucio de Azevedo, Maria Carolina Quecine
Mangroves are ecosystems located in the transition zone between land and sea that serve as a potential source of biotechnological resources. Brazil's extensive coast contains one of the largest mangrove forests in the world (encompassing an area of 25,000km(2) along all the coast). Endophytic bacteria were isolated from the following three plant species: Rhizophora mangle, Laguncularia racemosa and Avicennia nitida. A large number of these isolates, 115 in total, were evaluated for their ability to fix nitrogen and solubilize phosphorous...
July 19, 2017: Brazilian Journal of Microbiology: [publication of the Brazilian Society for Microbiology]
https://www.readbyqxmd.com/read/28772776/optimization-of-anodic-porous-alumina-fabricated-from-commercial-aluminum-food-foils-a-statistical-approach
#12
Eva Riccomagno, Amirreza Shayganpour, Marco Salerno
Anodic porous alumina is a known material based on an old industry, yet with emerging applications in nanoscience and nanotechnology. This is promising, but the nanostructured alumina should be fabricated from inexpensive raw material. We fabricated porous alumina from commercial aluminum food plate in 0.4 M aqueous phosphoric acid, aiming to design an effective manufacturing protocol for the material used as nanoporous filler in dental restorative composites, an application demonstrated previously by our group...
April 15, 2017: Materials
https://www.readbyqxmd.com/read/28772450/combining-bioactive-multifunctional-dental-composite-with-pamam-for-root-dentin-remineralization
#13
Shimeng Xiao, Kunneng Liang, Michael D Weir, Lei Cheng, Huaibing Liu, Xuedong Zhou, Yi Ding, Hockin H K Xu
Objectives. The objectives of this study were to: (1) develop a bioactive multifunctional composite (BMC) via nanoparticles of amorphous calcium phosphate (NACP), 2-methacryloyloxyethyl phosphorylcholine (MPC), dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of silver (NAg); and (2) investigate the effects of combined BMC + poly (amido amine) (PAMAM) on remineralization of demineralized root dentin in a cyclic artificial saliva/lactic acid environment for the first time. Methods. Root dentin specimens were prepared and demineralized with 37% phosphoric acid for 15 s...
January 22, 2017: Materials
https://www.readbyqxmd.com/read/28771900/selecting-chiral-binol-derived-phosphoric-acid-catalysts-general-model-to-identify-steric-features-essential-for-enantioselectivity
#14
Jolene Reid, Jonathan Goodman
Choosing the optimal catalyst for a new transformation is challenging because the ideal molecular requirements of the catalyst for one reaction do not always simply translate to another. Large groups at the 3,3' positions of the binaphthol rings are important for efficient stereoinduction but if they are too large this can lead to unusual or poor results. By applying a quantitative steric assessment of the substituents at the 3,3' positions of the binaphthol ring, we have systematically studied the effect of modulating this group on enantioselectivity for a wide range of reactions involving imines, and verified this analysis using ONIOM calculations...
August 3, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28771528/plasma-metabolomics-profiles-in-rats-with-acute-traumatic-brain-injury
#15
Fei Zheng, Zi-An Xia, Yi-Fu Zeng, Jie-Kun Luo, Peng Sun, Han-Jin Cui, Yang Wang, Tao Tang, Yan-Tao Zhou
Traumatic brain injury (TBI) is a major cause of mortality and disability worldwide. We validated the utility of plasma metabolomics analysis in the clinical diagnosis of acute TBI in a rat model of controlled cortical impact (CCI) using gas chromatography/mass spectrometry (GC/MS). Thirty Sprague-Dawley rats were randomly divided into two groups of 15 rats each: the CCI group and sham group. Blood samples were obtained from the rats within the first 24 h after TBI injury. GC/MS measurements were performed to evaluate the profile of acute TBI-induced metabolic changes, resulting in the identification of 45 metabolites in plasma...
2017: PloS One
https://www.readbyqxmd.com/read/28768951/characterization-and-evaluation-of-skin-permeation-of-tocopheryl-phosphoric-acid-loaded-phospholipid-nanoparticles
#16
Tomonobu Uchino, Yasunori Miyazaki, Ako Fujii, Yoshiyuki Kagawa
 Tocopheryl phosphoric acid (TPA, a hydrophilic vitamin E derivative) loaded liposome and glycerin containing phospholipid nanoparticles (GPLNP) were prepared using the film rehydration and extrusion method. Nanoparticle formulations were evaluated for size, zeta potential, and in vitro permeation across hairless mouse skin, and (31)P NMR spectral analysis was performed. The prepared formulations were stable for 2 weeks, and their mean nanoparticle size varied between 90 and 140 nm. Although glycerin did not affect the particle size of the empty (no TPA) system, TPA-loading resulted in the reduction of particle size and conferred a negative charge...
2017: Yakugaku Zasshi: Journal of the Pharmaceutical Society of Japan
https://www.readbyqxmd.com/read/28766490/validated-analytical-methods-for-the-determination-of-drugs-used-in-the-treatment-of-hyperemesis-gravidarum-in-multiple-formulations
#17
Ahmed S Saad, Ibrahim A Naguib, Mohammed E Draz, Hala E Zaazaa, Adel S Lashien
Quantitative multicomponent analysis is considered an analytical goal to save time and cost in analysis. Hence, this work aimed to provide sensitive and selective UV-spectrophotometric, chemometric manipulation, and ultra-performance LC (UPLC) methods for the determination of well-known coformulated antiemetics used in pregnancy, namely pyridoxine HCl (PYR), meclozine HCl, and cyclizine. The developed UV-spectrophotometric methods are dual wavelength in ratio spectra and first derivative of the ratio spectra with which PYR was determined selectively at 290...
August 1, 2017: Journal of AOAC International
https://www.readbyqxmd.com/read/28766480/development-and-validation-of-an-hplc-uv-method-to-quantify-tavaborole-during-in-vitro-transungual-permeation-studies
#18
Silvia Tampucci, Eleonora Terreni, Susi Burgalassi, Patrizia Chetoni, Daniela Monti
A selective and rapid reversed-phase HPLC-UV method was developed and validated to quantify tavaborole (TAV; AN2690) in biological samples, i.e., in receiving phase and in bovine hoof membrane extract derived from in vitro transungual permeation studies. A simple solid-liquid extraction procedure was used to recover the drug from the bovine hoof slices. TAV chromatographic separation was achieved on a Luna PFP column (150 × 4.6 mm, 5 μm) using a mobile phase consisting of a 70% phosphoric acid solution (10 mM, pH 2...
August 1, 2017: Journal of AOAC International
https://www.readbyqxmd.com/read/28765674/a-comparative-evaluation-of-retention-of-pit-and-fissure-sealants-placed-with-conventional-acid-etching-and-er-cr-ysgg-laser-etching-a-randomised-controlled-trial
#19
Gyanendra Kumar, Jatinder Kaur Dhillon, Ferah Rehman
Aim: The aim of this study was to compare the retention rates of sealant placed either with conventional acid etching or Er,Cr:YSGG laser pretreatment of enamel surface. Materials and methods: This is a prospective, single blind randomised controlled clinical trial enrolling 200 permanent first molars in 50 patients, aged 6-12 years for sealant placement. Study followed split mouth design where each side of the arch was randomly allocated to the two treatment group. Group A(Acid etch group): 37 % phosphoric acid (Scotchbond, 3M ESPE, Seefeld, Germany) was applied for 15 seconds, rinsed with water for 20 seconds and then air-dried using air spray...
December 30, 2016: Laser Therapy
https://www.readbyqxmd.com/read/28762669/white-spot-lesions-does-etching-really-matter
#20
Moufida Abufarwa, Robert D Voorhees, Venu G Varanasi, Phillip M Campbell, Peter H Buschang
AIM: The clinical significance of acid etching prior to orthodontic bonding is controversial. In the present study, we evaluated the effect of 15 seconds of acid etching on enamel demineralization. METHODS: Twenty-seven human molars were sectioned and assigned to two groups. Under standardized conditions, the enamel surfaces were imaged using FluoreCam to obtain baseline data. Group 1 was etched using 37% phosphoric acid for 15 seconds, rinsed with water, and then imaged again; group 2 was only rinsed with water...
August 1, 2017: Journal of Investigative and Clinical Dentistry
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