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Phosphoric acid

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https://www.readbyqxmd.com/read/28441624/various-soil-amendments-and-environmental-wastes-affect-the-im-mobilization-and-phytoavailability-of-potentially-toxic-elements-in-a-sewage-effluent-irrigated-sandy-soil
#1
Sabry M Shaheen, Mohamed S Shams, Mohamed R Khalifa, Mohamed A El-Dali, Jörg Rinklebe
Contamination of long-term sewage effluent irrigated soils by potentially toxic elements (PTEs) is a serious concern due to its high environmental and health risk. Our scientific hypothesis is that soil amendments can cause contradictory effects on the element mobilization and phytoavailability depending on the type of element and amendment. Therefore, we aimed to assess the impact of the application (1%) of several low cost amendments and environmental wastes on the (im)mobilization, availability, and uptake of Al, Cd, Cr, Cu, Fe, Mn, Ni, and Zn by sorghum (Sorghum bicolor) in a long term sewage effluent irrigated sandy soils collected from Egypt...
April 22, 2017: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/28440624/acid-base-catalysis-in-glycosidations-a-nature-derived-alternative-to-the-generally-employed-methodology
#2
Peng Peng, Richard R Schmidt
Inverting glycosyltransferases enforce in the active site an intramolecular, acid-base catalyzed glycosidation that, due to proximity of the donor anomeric carbon and the acceptor hydroxyl group, follows an SN2-type reaction. Spacers, tethering donor and acceptor via nonreacting functional groups, led in intramolecular glycosidations to excellent yields and, independent of the donor anomeric configuration, to either the α- or the β-anomer. The requirement of a demanding protecting group pattern confines the application of this efficient method...
April 25, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28439576/bond-strength-to-eroded-enamel-and-dentin-using-a-universal-adhesive-system
#3
Fabiana Cares Frattes, Marina Gullo Augusto, Carlos Rocha Gomes Torres, Cesar Rogério Pucci, Alessandra Bühler Borges
PURPOSE: To evaluate the influence of previous acid etching on the bond strength of a self-etch universal adhesive system on sound and eroded enamel and dentin. MATERIALS AND METHODS: Flat enamel and dentin surfaces were obtained from bovine incisors (n = 44) and divided into two groups according to the exposure to erosive conditions: sound (without erosion) and eroded (after erosive challenge with 0.3% citric acid, pH 2.6, 5 min, 4x/day, 5 days). Each group was then divided into two subgroups (n = 11) according to the application or not of 37% phosphoric acid before applying a universal self-etch adhesive...
April 21, 2017: Journal of Adhesive Dentistry
https://www.readbyqxmd.com/read/28439458/the-genomic-sequence-of-exiguobacterium-chiriqhucha-str-n139-reveals-a-species-that-thrives-in-cold-waters-and-extreme-environmental-conditions
#4
Ana Gutiérrez-Preciado, Carlos Vargas-Chávez, Mariana Reyes-Prieto, Omar F Ordoñez, Diego Santos-García, Tania Rosas-Pérez, Jorge Valdivia-Anistro, Eria A Rebollar, Andrés Saralegui, Andrés Moya, Enrique Merino, María Eugenia Farías, Amparo Latorre, Valeria Souza
We report the genome sequence of Exiguobacterium chiriqhucha str. N139, isolated from a high-altitude Andean lake. Comparative genomic analyses of the Exiguobacterium genomes available suggest that our strain belongs to the same species as the previously reported E. pavilionensis str. RW-2 and Exiguobacterium str. GIC 31. We describe this species and propose the chiriqhucha name to group them. 'Chiri qhucha' in Quechua means 'cold lake', which is a common origin of these three cosmopolitan Exiguobacteria. The 2,952,588-bp E...
2017: PeerJ
https://www.readbyqxmd.com/read/28434709/target-analysis-of-tert-butyldimethylsilyl-derivatives-of-nerve-agent-hydrolysis-products-by-selectable-one-dimensional-or-two-dimensional-gas-chromatography-mass-spectrometry
#5
Yasuo Seto, Masumi Tachikawa, Mieko Kanamori-Kataoka, Kikuo Sasamoto, Nobuo Ochiai
A target analysis method for the sensitive and discriminative determination of the nerve agent hydrolysis products alkyl methylphosphonic acids as their tert-butyldimethylsilyl (TBDMS) derivatives was developed using a combination of selectable one- and two-dimensional ((1)D/(2)D) GC-MS, and applied to the analysis of samples with significant interfering matrices. After sample drying, the alkylmethylphosphonic acids and methylphosphonic acid (MPA) were converted to TBDMS derivatives by addition of N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide with heating, and subjected to (1)D/(2)D GC-MS...
April 13, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28433905/pretreating-wheat-straw-by-phosphoric-acid-plus-hydrogen-peroxide-for-enzymatic-saccharification-and-ethanol-production-at-high-solid-loading
#6
Jingwen Qiu, Lunjie Ma, Fei Shen, Gang Yang, Yanzong Zhang, Shihuai Deng, Jing Zhang, Yongmei Zeng, Yaodong Hu
Wheat straw was pretreated by phosphoric acid plus hydrogen peroxide (PHP) for enzymatic hydrolysis and ethanol fermentation at high solid loadings. Results indicated solid loading could reach 20% with 77.4% cellulose-glucose conversion and glucose concentration of 164.9g/L in hydrolysate, it even was promoted to 25% with only 3.4% decrease on cellulose-glucose conversion as the pretreated-wheat straw was dewatered by air-drying. 72.9% cellulose-glucose conversion still was achieved as the minimized enzyme input of 20mg protein/g cellulose was employed for hydrolysis at 20% solid loading...
April 12, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28433639/optimization-of-atrazine-and-imidacloprid-removal-from-water-using-biochars-designing-single-or-multi-staged-batch-adsorption-systems
#7
Abhishek Mandal, Neera Singh
BACKGROUND: Contamination of surface and ground water by pesticides from agricultural runoff and industrial discharge is one of the main causes of aqueous contaminations world over. Biochar, agricultural waste derived highly aromatic substance produced after pyrolysis and carbonification of biomass have exhibited good adsorption capacity for pesticides and can be used to develop on-site bio-purification systems for organic contaminant removal from polluted waters. However, high amounts of adsorbent required in single stage-batch sorption plant increases the cost of water treatment; therefore, multistage plant systems were investigated...
April 5, 2017: International Journal of Hygiene and Environmental Health
https://www.readbyqxmd.com/read/28433536/assessment-of-enamel-cracks-at-adhesive-cavosurface-margin-using-three-dimensional-swept-source-optical-coherence-tomography
#8
Tomoko Tabata, Yasushi Shimada, Alireza Sadr, Junji Tagami, Yasunori Sumi
OBJECTIVES: Swept-source optical coherence tomography (SS-OCT) can construct cross-sectional images of internal biological structures. The aim of this study was to evaluate enamel cracks at the cavosurface margin of composite restorations using SS-OCT. METHODS: Bowl-shaped cavities were prepared at two locations (mid-coronal and cervical regions) on the enamel surface of 60 bovine teeth. Half of the cavities (30) were treated with phosphoric acid gel. A two-step self-etch adhesive (Clearfil SE Bond) was applied to all cavities and a flowable composite was placed in bulk...
April 19, 2017: Journal of Dentistry
https://www.readbyqxmd.com/read/28431687/a-rapid-impregnation-method-for-loading-desired-amounts-of-extractant-on-prepacked-reversed-phase-columns-for-high-performance-liquid-chromatographic-separation-of-metal-ions
#9
Muhammad Ramzan, Dejene Kifle, Grethe Wibetoe
A time-efficient impregnation method for loading extractant onto reversed-phase columns was developed, using di-(2-ethylhexyl) phosphoric acid (HDEHP) as a model extractant. The optimal loading conditions for the impregnation process of a standard analytical scale column was achieved by dissolving an appropriate amount of HDEHP (per void volume) in n-pentane, flushing the column with two void volumes (5mL) of impregnation solution and heating the column for a short time to remove the solvent. The process takes about one hour, a significant time reduction compared to commonly used impregnation methods (17-23h)...
April 7, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28430810/efficacy-of-fluoride-varnishes-for-preventing-enamel-demineralization-after-interproximal-enamel-reduction-qualitative-and-quantitative-evaluation
#10
Ascensión Vicente, Antonio José Ortiz Ruiz, Belén Manuela González Paz, José García López, Luis-Alberto Bravo-González
OBJECTIVES: To evaluate quantitatively and qualitatively the changes produced to enamel after interproximal reduction and subjected to demineralization cycles, after applying a fluoride varnish (Profluorid) and a fluoride varnish containing tricalcium phosphate modified by fumaric acid (Clinpro White). MATERIALS AND METHODS: 138 interproximal dental surfaces were divided into six groups: 1) Intact enamel; 2) Intact enamel + demineralization cycles (DC); 3) Interproximal Reduction (IR); 4) IR + DC; 5) IR + Profluorid + DC; 6) IR + Clinpro White + DC...
2017: PloS One
https://www.readbyqxmd.com/read/28430400/highly-sensitive-hplc-method-for-the-determination-of-galantamine-in-human-plasma-and-urine-through-derivatization-with-dansyl-chloride-using-fluorescence-detector
#11
Elif Özdemir, Sevgi Tatar Ulu
A new method based on fluorescence derivatization with 5-(dimethylamino) naphthalene-1-sulfonyl chloride (dansyl chloride) was developed for the quantitative determination of galantamine in human plasma and urine using high-performance liquid chromatography. The reaction between galantamine and dansyl chloride was optimally realized in 30 min at room temperature and pH 10.5, with a reagent to galantamine molar ratio of 2.13. The derivative was extracted with dichloromethane, and the extract was dried under a nitrogen stream and dissolved in the mobile phase...
April 21, 2017: Luminescence: the Journal of Biological and Chemical Luminescence
https://www.readbyqxmd.com/read/28427449/urolithiasis-analysis-in-a-multiethnic-population-at-a-tertiary-hospital-in-nairobi-kenya
#12
Francis K Wathigo, Alfred Hayombe, Daniel Maina
BACKGROUND: Urolithiasis is a global problem whose incidence is reported to be on the rise across the world. Previously, urolithiasis was reported as being rare among the indigenous African population but recent data suggest otherwise. This study reviewed the demographic and clinical characteristics of patients with urolithiasis seen at the Aga Khan University hospital Nairobi (AKUHN) as well as the chemical composition of the stones and the modalities of therapy used. METHODS: This was a retrospective study which utilized patients' clinical and laboratory records from 2013 to 2014...
April 20, 2017: BMC Research Notes
https://www.readbyqxmd.com/read/28422595/microleakage-of-sealants-after-phosphoric-acid-er-yag-laser-and-air-abrasion-enamel-conditioning-systematic-review-and-meta-analysis
#13
Ana Caroline Fumes, Daniele Lucca Longo, Andiara De Rossi, Tatiana Kelly da Silva Fidalgo, Francisco Wanderley Garcia de Paula E Silva, Maria Cristina Borsatto, Erika Calvano Küchler
PURPOSE: The aim of this systematic review and meta-analysis is to answer the focused question: Does the application of phosphoric acid, Er:YAG laser and air abrasion enamel conditioning methods previous to the oclusal sealant application in human permanent molars influence the microleakage? STUDY DESIGN: A literature research was carried out in the Pubmed Medline, Web of Science, Scopus and Cochrane databases using with the MeSH terms and keyword search strategy...
2017: Journal of Clinical Pediatric Dentistry
https://www.readbyqxmd.com/read/28421632/rigidly-tethered-bis-phosphoric-acids-generation-of-tunable-chiral-fluorescent-frameworks-and-unexpected-selectivity-for-the-detection-of-ferric-ions
#14
Frescilia Octa-Smolin, Raja Mitra, Maike Thiele, Constantin-Gabriel Daniliuc, Linda Stegemann, Cristian Strassert, Jochen Niemeyer
We describe the straightforward synthesis of a series of bis-phosphoric acids (R,R)-1a/b/c/d, featuring two chiral 1,1´-binaphthyl-phosphoric acid units which are tethered by rigid, π-conjugated linkers. The nature of the linker has a profound influence on the properties of the bis-phosphoric acids, such as their self-association behavior and their interaction with metal ions. This led to the identification of one preferred bis-phosphoric acid (R,R)-1d, which shows selective fluorescence quenching in the presence of ferric ions (Fe3+)...
April 18, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28418674/reversing-enantioselectivity-using-noncovalent-interactions-in-asymmetric-dearomatization-of-%C3%AE-naphthols-the-power-of-3-3-substituents-in-chiral-phosphoric-acid-catalysts
#15
Avtar Changotra, Sandip Das, Raghavan B Sunoj
The sense of enantioselectivity in asymmetric dearomative amination of β-naphthols is reported to pivotally depend on the 3,3' substituents on the chiral BINOL-phosphoric acid (CPA) catalysts. The origin of reversal in the sense of stereoinduction from R to S, when the aryl substituent is changed from 3,5-(CF3)2-C6H3 (CPA-1) to 9-anthryl (CPA-2), has been identified as arising due to the change in the pattern of noncovalent interactions (from predominantly C-H···F to C-H···π interactions) in the stereocontrolling transition states...
April 18, 2017: Organic Letters
https://www.readbyqxmd.com/read/28418118/enantioselective-heck-matsuda-arylations-through-chiral-anion-phase-transfer-of-aryl-diazonium-salts
#16
Carolina M Avila, Jigar S Patel, Yernaidu Reddi, Masato Saito, Hosea M Nelson, Hunter P Shunatona, Matthew S Sigman, Raghavan B Sunoj, F Dean Toste
A mild, asymmetric Heck-Matsuda reaction of five-, six- and seven-membered ring alkenes and aryl diazonium salts is presented. High yields and enantioselectivities were achieved using Pd(0) and chiral anion co-catalysts, the latter functioning as a chiral anion phase-transfer (CAPT) reagent. For certain substrate classes, the chiral anion catalysts were modulated to minimize the formation of undesired by-products. More specifically, BINAM-derived phosphoric acid catalysts were shown to prevent alkene isomerization in cyclopentene and cycloheptene starting materials...
April 18, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28413590/effect-of-nano-hydroxyapatite-toothpaste-on-microhardness-ofartificial-carious-lesions-created-on-extracted-teeth
#17
Asghar Ebadifar, Mohammad Nomani, Sayed Ali Fatemi
Background. Many types of toothpastes contain substances that can remineralize initial enamel caries. This study aimed to assess the effect of nano-hydroxyapatite (NHA) on microhardness of artificially created carious lesions. Methods. In this in vitro study, NHA was prepared using sol-gel technique and added to the toothpaste with 7% concentration. A total of 80 extracted sound teeth were collected. The crowns were polished using 500-grit abrasive paper. The specimens were randomly coded from 1 to 80. Number 1 to 40 were assigned to group A and numbers 41 to 80 to group B...
2017: Journal of Dental Research, Dental Clinics, Dental Prospects
https://www.readbyqxmd.com/read/28411891/recombinant-expression-of-thermobifida-fusca-e7-lpmo-in-pichia-pastoris-and-escherichia-coli-and-their-functional-characterization
#18
Kelly B Rodrigues, Jéssica K A Macêdo, Tallyta Teixeira, Jéssica S Barros, Ana C B Araújo, Fernanda P Santos, Betânia F Quirino, Bruno S A F Brasil, Thaís F C Salum, Patrícia V Abdelnur, Léia C L Fávaro
The discovery of lytic polysaccharides monooxygenases copper dependent (LPMOs) revolutionized the classical concept that the cleavage of cellulose is a hydrolytic process in recent years. These enzymes carry out oxidative cleavage of cellulose (and other polysaccharides), acting synergistically with cellulases and other hydrolases. In fact, LPMOs have the potential for increasing the efficiency of the lignocellulosic biomass conversion in biofuels and high value chemicals. Among a small number of microbial LPMOs that have been characterized, some LPMOs were expressed and characterized biochemically from the bacteria Thermobifida fusca, using the host Escherichia coli...
April 9, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28410951/effect-of-acidity-on-the-physicochemical-properties-of-%C3%AE-and-%C3%AE-chitin-nanofibers
#19
Shin Suenaga, Kazuhide Totani, Yoshihiro Nomura, Kazuhiko Yamashita, Iori Shimada, Hiroshi Fukunaga, Nobuhide Takahashi, Mitsumasa Osada
We have investigated whether acidity can be used to control the physicochemical properties of chitin nanofibers (ChNFs). In this study, we define acidity as the molar ratio of dissociated protons from the acid to the amino groups in the raw chitin powder. The effect of acidity on the physicochemical properties of α- and β-ChNFs was compared. The transmittance and viscosity of the β-ChNFs drastically and continuously increased with increasing acidity, while those of the α-ChNFs were not affected by acidity...
April 11, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28406922/3d-fabrication-and-characterization-of-phosphoric-acid-scaffold-with-a-ha-%C3%AE-tcp-weight-ratio-of-60-40-for-bone-tissue-engineering-applications
#20
Yanen Wang, Kai Wang, Xinpei Li, Qinghua Wei, Weihong Chai, Shuzhi Wang, Yu Che, Tingli Lu, Bo Zhang
A key requirement for three-dimensional printing (3-DP) at room temperature of medical implants depends on the availability of printable and biocompatible binder-powder systems. Different concentration polyvinyl alcohol (PVA) and phosphoric acid solutions were chosen as the binders to make the artificial stent biocompatible with sufficient compressive strength. In order to achieve an optimum balance between the bioceramic powder and binder solution, the biocompatibility and mechanical properties of these artificial stent samples were tested using two kinds of binder solutions...
2017: PloS One
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