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Phosphoric acid

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https://www.readbyqxmd.com/read/28644411/on-the-reaction-of-carbonyl-diphosphonic-acid-with-hydroxylamine-and-o-alkylhydroxylamines-unexpected-degradation-of-p-c-p-bridge
#1
Olga A Khomich, Dmitry V Yanvarev, Roman A Novikov, Alexey B Kornev, Elina Puljulla, Jouko Vepsäläinen, Alex R Khomutov, Sergey N Kochetkov
Derivatives of methylenediphosphonic acid possess wide spectra of biological activities and are used in enzymology as research tools as well as in practical medicine. Carbonyl diphosphonic acid is a promising starting building block for synthesis of functionally substituted methylenediphosphonates. Investigation of the interaction of carbonyl diphosphonic acid with hydroxylamine clearly demonstrates that it is impossible to isolate oxime within the pH range 2-12, while only cyanophosphonic and phosphoric acids are the products of the fast proceeding Beckmann-like fragmentation...
June 23, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28642929/influence-of-dentin-pretreatment-on-bond-strength-of-universal-adhesives
#2
Claudio Poggio, Riccardo Beltrami, Marco Colombo, Marco Chiesa, Andrea Scribante
Objective: The purpose of the present study was to compare bond strength of different universal adhesives under three different testing conditions: when no pretreatment was applied, after 37% phosphoric acid etching and after glycine application. Materials and methods: One hundred and fifty bovine permanent mandibular incisors were used as a substitute for human teeth. Five different universal adhesives were tested: Futurabond M+, Scotchbond Universal, Clearfil Universal Bond, G-Premio BOND, Peak Universal Bond...
January 2017: Acta Biomaterialia Odontologica Scandinavica
https://www.readbyqxmd.com/read/28638864/protective-effect-of-vanillic-acid-on-ovariectomy-induced-osteoporosis-in-rats
#3
Yong Gui Wang, Liang Bo Jiang, Bo Gou
BACKGROUND: The need for an anti-osteoporotic agent is in high demand since osteoporosis contributes to high rates of disability or impairment (high osteoporotic fracture), morbidity and mortality. Hence, the present study is designed to evaluate the protective effects of vanillic acid (VA) against bilateral ovariectomy-induced osteoporosis in female Sprague-Dawley (SD) rats. MATERIALS AND METHODS: Forty healthy female adult SD rats were separated in to four groups with sham-operated control with bilateral laprotomy (Sham; n = 10), bilateral overiectomy (OVX; n = 10) group, OVX rats were orallay administrated with 50 mg/kg b...
2017: African Journal of Traditional, Complementary, and Alternative Medicines: AJTCAM
https://www.readbyqxmd.com/read/28633093/fracture-resistance-of-ceramic-and-polymer-based-occlusal-veneer-restorations
#4
Majed Al-Akhali, Mohamed Sad Chaar, Adham Elsayed, Abdulaziz Samran, Matthias Kern
OBJECTIVES: The purpose of this in vitro study was to evaluate the influence of thermodynamic loading on the durability and fracture resistance behavior of occlusal veneers fabricated from different biomedical dental CAD/CAM materials. METHODS: The occlusal surfaces of 64 extracted premolars were prepared in the enamel layer and restored with occlusal veneers with a fissure/cusp thickness of 0.5/0.8mm made from four different dental CAD/CAM materials: group LD lithium disilicate (e...
June 13, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28629707/theoretical-investigation-of-the-selective-dehydration-and-dehydrogenation-of-ethanol-catalyzed-by-small-molecules
#5
Yanqun Wang, Yizhen Tang, Youxiang Shao
Catalytic dehydration and dehydrogenation reactions of ethanol have been investigated systematically using the ab initio quantum chemistry methods The catalysts include water, hydrogen peroxide, formic acid, phosphoric acid, hydrogen fluoride, ammonia, and ethanol itself. Moreover, a few clusters of water and ethanol were considered to simulate the catalytic mechanisms in supercritical water and supercritical ethanol. The barriers for both dehydration and dehydrogenation can be reduced significantly in the presence of the catalysts...
May 17, 2017: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/28627172/regiodivergent-glycosylations-of-6-deoxy-erythronolide-b-and-oleandomycin-derived-macrolactones-enabled-by-chiral-acid-catalysis
#6
Jia-Hui Tay, Alonso J Argüelles, Matthew D DeMars, Paul M Zimmerman, David H Sherman, Pavel Nagorny
This work describes the first example of using chiral catalysts to control site-selectivity for the glycosylations of complex polyols such as 6-deoxyerythronolide B and oleandomycin-derived macrolactones. The regiodivergent introduction of sugars at the C3, C5, and C11 positions of macrolactones was achieved by selecting appropriate chiral acids as catalysts or through introduction of stoichiometric boronic acid-based additives. BINOL-based chiral phosphoric acids (CPAs) were used to catalyze highly selective glycosylations at the C5 positions of macrolactones (up to 99:1 rr), whereas the use of SPINOL-based CPAs resulted in selectivity switch and glycosylation of the C3 alcohol (up to 91:9 rr)...
June 19, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28623337/impact-of-module-x2-and-carbohydrate-binding-module-3-on-the-catalytic-activity-of-associated-glycoside-hydrolases-towards-plant-biomass
#7
Nandita Pasari, Nidhi Adlakha, Mayank Gupta, Zeenat Bashir, Girish H Rajacharya, Garima Verma, Manoj Munde, Rakesh Bhatnagar, Syed Shams Yazdani
Cellulolytic enzymes capable of hydrolyzing plant biomass are secreted by microbial cells specifically in response to the carbon substrate present in the environment. These enzymes consist of a catalytic domain, generally appended to one or more non-catalytic Carbohydrate Binding Module (CBM), which enhances their activity towards recalcitrant biomass. In the present study, the genome of a cellulolytic microbe Paenibacillus polymyxa A18 was annotated for the presence of CBMs and analyzed their expression in response to the plant biomass and model polysaccharides Avicel, CMC and xylan using quantitative PCR...
June 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28622650/the-positive-effect-of-phosphogypsum-supplemented-composts-on-potato-plant-growth-in-the-field-and-tuber-yield
#8
Mariem Kammoun, Imen Ghorbel, Safa Charfeddine, Lotfi Kamoun, Radhia Gargouri-Bouzid, Oumèma Nouri-Ellouz
The production of phosphoric acid from phosphate rock leads to an industrial by-product called phosphogypsum (PG). One ton of phosphoric acid generates 5 tons of PG that is frequently stocked near the production units. Several attempts were made to test PG valorization via soil amendment because of its phosphate, sulphate and calcium content. In this study, the use of PG in composting was envisaged. Composts were produced by mixing olive oil wastes and spent coffee grounds. Two concentrations of PG, 10% (A10) and 30% (A30), were tested in composting substrate in addition to control compost without PG (AT)...
June 13, 2017: Journal of Environmental Management
https://www.readbyqxmd.com/read/28618154/catalytic-enantioselective-aza-pinacol-rearrangement
#9
Yuanyuan Yu, Jingwen Li, Long Jiang, Jing-Ren Zhang, Liansuo Zu
The first catalytic enantioselective asymmetric aza-pinacol rearrangement is reported. The reactions are catalyzed by a chiral phosphoric acid through a highly-organized transition state involving a cyclic aza-ortho-xylylene intermediate to afford the indoline structures with good to excellent enantioselectivities. The synthetic utility has been demonstrated by the asymmetric synthesis of a key intermediate to natural product minfiensine and the identification of a chiral lead compound to repress antibiotic resistance...
June 15, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28612527/-the-effect-of-p-jak1-p-stat3-signaling-way-in-intervening-nafld-by-blueberry-probiotic-serum
#10
Juan-Juan Zhu, Ming-Liang Cheng, Ming-Yu Zhou, Xue-Ke Zhao
OBJECTIVES: To explore the mechanism of interlukin-22 (IL-22)-mediated phosphor-Janus kinase-1(p-JAK1)/phosphor-signal transducer and activator of transcription 3 (p-STAT3) signaling way in the experiment of improving non-alcholic fatty liver disease (NAFLD) by blueberry probiotic serum. METHODS: The rat serums with low-, medium-, and high-dose of 10% blueberry probiotics, as well as saline were prepared. NAFLD model was built by inducing normal liver cell line L-02 with free fatty acid (FFA)...
March 2017: Sichuan da Xue Xue Bao. Yi Xue Ban, Journal of Sichuan University. Medical Science Edition
https://www.readbyqxmd.com/read/28609093/disilicate-assisted-iron-electrolysis-for-sequential-fenton-oxidation-and-coagulation-of-aqueous-contaminants
#11
Jiaxin Cui, Xu Wang, Jing Zhang, Xiaoyu Qiu, Dihua Wang, Ying Zhao, Beidou Xi, Akram Alshawabkeh, Xuhui Mao
Sodium disilicate (SD), an inorganic and environmentally friendly ligand, is introduced into the conventional iron electrolysis system to achieve an oxidizing Fenton process to degrade organic pollutants. Electrolytic ferrous ions, which are complexed by the disilicate ions, can chemically reduce dioxygen molecules via consecutive reduction steps, producing H2O2 for the Fenton-oxidation of organics. At the near-neutral pH (from 6 to 8), the disilicate-Fe(II) complexes possess strong reducing capabilities; therefore, a near-neutral pH rather than an acid condition is preferable for the disilicate-assisted iron electrolysis (DAIE) process...
June 13, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28608463/effect-of-etching-on-bonding-of-a-self-etch-adhesive-to-dentine-affected-by-amelogenesis-imperfecta
#12
Don Jeevanie Epasinghe, Cynthia Kar Yung Yiu
AIM: Dentine affected by amelogenesis imperfecta (AI) is histologically altered due to loss of hypoplastic enamel and becomes hypermineralized. In the present study, we examined the effect of additional acid etching on microtensile bond strength of a self-etch adhesive to AI-affected dentine. METHODS: Flat coronal dentine obtained from extracted AI-affected and non-carious permanent molars were allocated to two groups: (a) Clearfil SE Bond (control); and (b) Clearfil SE Bond and additional etching with 34% phosphoric acid for 15 seconds...
June 13, 2017: Journal of Investigative and Clinical Dentistry
https://www.readbyqxmd.com/read/28598364/isoprenoids-production-from-lipid-extracted-microalgal-biomass-residues-using-engineered-e-coli
#13
Sumeng Wang, Jianming Yang
Microalgae are recognized as a third generation feedstock for biofuel production due to their rapid growth rates and lignin-free characteristics. In this study, a lipid extracted microalgal biomass residues was used as the raw material to produce isoprene, α-pinene and β-pinene with an engineered E. coli strain. We adopted an optimal sulfuric acid hydrolysis method (1:7 ratio of solid to acid solution, 32% (w/v) concentration of sulfuric acid solution at 90 °C for 90 min) to efficiently convert holocellulose into glucose efficiently (6...
June 9, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28597513/complexity-in-acid-base-titrations-multimer-formation-between-phosphoric-acids-and-imines
#14
Christian Malm, Heejae Kim, Manfred Wagner, Johannes Hunger
Solutions of Brønsted acids with bases in aprotic solvents are not only common model systems to study the fundamentals of proton transfer pathways but are also highly relevant to Brønsted acid catalysis. Despite their importance the light nature of the proton makes characterization of acid-base aggregates challenging. Here, we track such acid-base interactions over a broad range of relative compositions between diphenyl phosphoric acid and the base quinaldine in dichloromethane, by using a combination of dielectric relaxation and NMR spectroscopy...
June 8, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28597311/integrated-process-for-ethanol-biogas-and-edible-filamentous-fungi-based-animal-feed-production-from-dilute-phosphoric-acid-pretreated-wheat-straw
#15
Ramkumar B Nair, Maryam M Kabir, Patrik R Lennartsson, Mohammad J Taherzadeh, Ilona Sárvári Horváth
Integration of wheat straw for a biorefinery-based energy generation process by producing ethanol and biogas together with the production of high-protein fungal biomass (suitable for feed application) was the main focus of the present study. An edible ascomycete fungal strain Neurospora intermedia was used for the ethanol fermentation and subsequent biomass production from dilute phosphoric acid (0.7 to 1.2% w/v) pretreated wheat straw. At optimum pretreatment conditions, an ethanol yield of 84 to 90% of the theoretical maximum, based on glucan content of substrate straw, was observed from fungal fermentation post the enzymatic hydrolysis process...
June 8, 2017: Applied Biochemistry and Biotechnology
https://www.readbyqxmd.com/read/28597008/effect-of-reduced-phosphoric-acid-pre-etching-times-%C3%A2-on-enamel-surface-characteristics-and-shear-fatigue-strength-using-universal-adhesives
#16
Akimasa Tsujimoto, Nicholas G Fischer, Wayne W Barkmeier, Andrew G Baruth, Toshiki Takamizawa, Mark A Latta, Masashi Miyazaki
PURPOSE: To examine the effect of reduced phosphoric acid pre-etching times on enamel fatigue bond strength of universal adhesives and surface characteristics by using atomic force microscopy (AFM). MATERIALS AND METHODS: Three universal adhesives were used in this study (Clearfil Universal Bond [C], G-Premio Bond [GP], Scotchbond Universal Adhesive [SU]). Four pre-etching groups were employed: enamel pre-etched with phosphoric acid and immediately rinsed with an air-water spray, and enamel pre-etched with phosphoric acid for 5, 10, or 15 s...
June 8, 2017: Journal of Adhesive Dentistry
https://www.readbyqxmd.com/read/28597005/acid-etching-with-modified-phosphoric-acid-to-increase-the-longevity-of-the-bonded-interface
#17
Alessandro D Loguercio, Pamela Malaquias, Fabiane Pereira Dos Santos, Viviane Hass, Rodrigo Stanislawczuk, Suellen Nogueira Linares Lima, Matheus Coelho Bandeca, Alessandra Reis
PURPOSE: To evaluate the effect of three phosphoric acids modified with chlorhexidine (CHX), benzalkonium chloride (BAC), or proanthocyanidins (PRO) and one conventional phosphoric acid (CON) on the immediate (24 h; IM) and 1-year composite-dentin microtensile bond strength (μTBS) and nanoleakage (NL), using an etch-and-rinse adhesive. MATERIALS AND METHODS: A flat dentin surface was exposed on 28 caries-free extracted molars, which were then randomly assigned to four groups (n = 7)...
June 8, 2017: Journal of Adhesive Dentistry
https://www.readbyqxmd.com/read/28594267/a-plant-pathogenic-bacterium-exploits-the-tricarboxylic-acid-cycle-metabolic-pathway-of-its-insect-vector
#18
Nabil Killiny, Yasser Nehela, Faraj Hijaz, Christopher I Vincent
Huanglongbing in citrus is caused by a phloem-limited, uncultivable, gram-negative α-proteobacterium, Candidatus Liberibacter asiaticus (CLas). CLas is transmitted by the phloem-sucking insect, Diaphorina citri (Hemiptera: Liviidae), in a persistent, circulative, and propagative manner. In this study, we investigated the metabolomic and respiration rates changes in D. citri upon infection with CLas using gas chromatography-mass spectrometry (GC-MS) and gas exchange analysis. The level of glycine, L-serine, L-threonine, and gamma-amino butyric acid were higher in CLas-infected D...
June 8, 2017: Virulence
https://www.readbyqxmd.com/read/28590078/separation-of-single-base-sequential-isomers-of-single-stranded-dna-by-capillary-electrophoresis-and-its-application-in-the-discrimination-of-single-base-dna-mutations
#19
Takao Sakurai, Hitoshi Hoshino, Toru Takahashi
Separation of single-base-substitution sequential DNA isomers remains one of the most challenging tasks in DNA separation by capillary electrophoresis. We developed a simple, versatile capillary electrophoresis technique for the separation of single-base sequential isomers of DNA having the same chain length. This technique is based on charge differences resulting from the different protonation (acid dissociation) properties of the four DNA bases. A mixture of 13 single-base sequential isomers of 12-mer single-stranded DNA was separated by using an electrophoretic buffer solution containing 20 mM phosphoric acid (pH 2...
June 7, 2017: Journal of Separation Science
https://www.readbyqxmd.com/read/28570759/catalytic-asymmetric-conjugate-addition-of-indolizines-to-%C3%AE-%C3%AE-unsaturated-ketones
#20
José Tiago Menezes Correia, Benjamin List, Fernando Coelho
A catalytic enantioselective conjugate addition of indolizines to enones is described. The chiral phosphoric acid (S)-TRIP activates α,β-unsaturated ketones, thereby promoting an enantioface-differentiating attack by indolizines. Using this reaction, several alkylated indolizines were synthesized in good yields and with enantiomeric ratios of up to 98:2.
June 26, 2017: Angewandte Chemie
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