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Phosphoric acid

M Heres, Y Wang, P J Griffin, C Gainaru, A P Sokolov
Phosphoric acid has one of the highest intrinsic proton conductivities of any known liquids, and the mechanism of this exceptional conductivity remains a puzzle. Our detailed experimental studies discovered a strong isotope effect in the conductivity of phosphoric acids caused by (i) a strong isotope shift of the glass transition temperature and (ii) a significant reduction of the energy barrier by zero-point quantum fluctuations. These results suggest that the high conductivity in phosphoric acids is caused by a very efficient proton transfer mechanism, which is strongly assisted by quantum effects...
October 7, 2016: Physical Review Letters
Min Shi, Liang Ma, Li Zhou, Ping Fu
Aristolochic acid nephropathy (AAN) is a progressive kidney disease caused by a Chinese herb containing aristolochic acid. Excessive death of renal tubular epithelial cells (RTECs) characterized the acute phase of AAN. Therapies for acute AAN were limited, such as steroids and angiotensin-receptor blockers (ARBs)/angiotensin-converting enzyme inhibitors (ACEIs). It was interesting that, in acute AAN, female patients showed relative slower progression to renal failure than males. In a previous study, female hormone 17β-estradiol (E2) was found to attenuate renal ischemia-reperfusion injury...
October 18, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Kesavan Balakumaran, Mosesbabu Janagili, Nagaraju Rajana, Sureshbabu Papureddy, Jayashree Anireddy
Alpha glucoside inhibitors used to treat type-2 diabetes mellitus (DM) are likely to be safe and effective. These agents are most effective for postprandial hyperglycemia. Miglitol is a type of drug used to treat type-2 DM. A simple, selective, linear, precise and accurate reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for a related substance of miglitol and its identification, and characterization was done by different mass spectrometry techniques. The gradient method at a flow rate of 1...
October 14, 2016: Scientia Pharmaceutica
Valentina Franco, Roberto Marchiselli, Cinzia Fattore, Elena Tartara, Giovambattista De Sarro, Emilio Russo, Emilio Perucca
BACKGROUND: Perampanel, a new specific non-competitive AMPA receptor antagonist, has been recently approved in the United States and the European Union for the adjunctive treatment of focal seizures and primary generalized tonic-clonic seizures associated with idiopathic generalized epilepsy. A positive relationship between plasma perampanel concentration and improvement in seizure control has been identified in regulatory trials, suggesting that therapeutic drug monitoring (TDM) could be useful in optimizing clinical response in patients with epilepsy treated with perampanel...
October 6, 2016: Therapeutic Drug Monitoring
Claudia Weilbeer, Marcel Sickert, Sergej Naumov, Christoph Schneider
We disclose herein the first enantioselective aza-Diels-Alder reaction of b-alkyl-substituted vinylketene silyl-O,O-acetals and imines furnishing a broad range of optically highly enriched 4-alkyl-substituted 2-piperidones. As catalyst for this one-pot reaction we employed a chiral phosphoric acid which effects a vinylogous Mannich reaction directly followed by ring-closure to the lactam. Subsequent fully diastereoselective transformations including hydrogenation, enolate alkylation, and lactam alkylation/reduction processes converted the cycloadducts into various highly substituted piperidines of great utility for the synthesis of natural products and medicinally active compounds...
October 17, 2016: Chemistry: a European Journal
Xiao-Xue Sun, Hong-Hao Zhang, Guo-Hao Li, Ying-Ying He, Feng Shi
The first catalytic asymmetric cycloaddition using 2-indolylmethanols as 3C building blocks has been established by a chiral phosphoric acid-catalyzed enantioselective and regioselective [3+3] cycloaddition of 2-indolylmethanols with azomethine ylides, which constructed biologically important tetrahydro-γ-carboline frameworks in high yields and excellent enantioselectivities (up to 83 % yield, 99:1 e.r.). This reaction not only represents the first application of 2-indolylmethanols as 3C building blocks in catalytic asymmetric cycloadditions, but also has established an abnormal regioselectivity in indolylmethanol-involved transformations...
October 13, 2016: Chemistry: a European Journal
Yayu Huo, Yang Gao, Jie Mi, Xinrui Wang, Huimin Jiang, Hailong Zhang
Rosa davurica Pall. has been used as a traditional Oroqen medicine to treat dyspepsia, gastroenterologia, menoxenia and other diseases. In this study, the chemical constituents research on the fruit pulp of R. davurica led to the isolation and identification of nine bioactive pentacyclic triterpenoids and five of them were isolated from the plant for the first time. Subsequently a simple and rapid high-performance liquid chromatography (HPLC) method was established for the simultaneous quantification of the nine triterpenoids...
October 12, 2016: Journal of Chromatographic Science
Muhammad Nasimullah Qureshi, Guenther Stecher, Guenther Karl Bonn
Flavonoids have been of considerable importance and interest because of their medicinal activity. Responding to their numerous health benefits, a comparative study on the quantitative determination of total polyphenolic compounds and flavonoids was carried out in Achillea millefolium and Equisetum arvense. Total polyphenolic compounds were quantified by Folin-Ciocalteau method using different solvents in order to prove their extraction efficiency. Focus within total polyphenolic quantification study was placed on the traditional reflux and solvents used were: water, 100% acetone, 100% ethanol, 80% ethanol, 50% methanol and 70% methanol...
September 2016: Pakistan Journal of Pharmaceutical Sciences
Jingwen Qiu, Qing Wang, Fei Shen, Gang Yang, Yanzong Zhang, Shihuai Deng, Jing Zhang, Yongmei Zeng, Chun Song
Wheat straw was pretreated by phosphoric acid plus hydrogen peroxide (PHP), in which temperature, time, and H3PO4 proportion for pretreatment were investigated by using response surface method. Results indicated that hemicellulose and lignin removal positively responded to the increase of pretreatment temperature, H3PO4 proportion, and time. H3PO4 proportion was the most important variable to control cellulose recovery, followed by pretreatment temperature and time. Moreover, these three variables all negatively related to cellulose recovery...
October 11, 2016: Applied Biochemistry and Biotechnology
Ferah Rehman, Gyanendra Kumar, Mridula Goswami, Jatinder Kaur Dhillon
Aim: The aim of this invitro study is to evaluate the shear bond strength of reattached fractured incisor fragments using Er,Cr:YSGG laser and conventional acid etching without additional tooth preparation. Materials and methods: Forty extracted human teeth were divided in two groups of 20 each (Groups A and B). In Group A, fractured surface was treated by an Er, Cr: YSGG laser system (Waterlase MD, Biolase Technology Inc., San Clemente, CA, USA) operating at a wavelength of 2,780 nm and frequency of 20 Hz...
June 29, 2016: Laser Therapy
Hua-Chen Lin, Pu-Sheng Wang, Zhong-Lin Tao, Yu-Gen Chen, Zhi-Yong Han, Liu-Zhu Gong
A highly enantioselective allylic C-H alkylation reactions of allylarenes with pyrazol-5-ones have been established by the cooperative catalysis of a chiral palladium complex and chiral Brønsted acid to afford a wide spectrum of functionalized chiral N-heterocycles with an all-carbon quaternary stereogenic center in high yields and with high levels of enantioselectivity (up to 96% ee), wherein the chiral ligand and phosphoric acid showed synergistic effect on the control of stereoselectivity. In addition, the first Pd-catalyzed asymmetric allylic C-H alkylation of 1,4-pentadienes with pyrazol-5-ones has been realized to furnish highly functionalized pyrazol-5-ones in high enantioselectivities...
October 9, 2016: Journal of the American Chemical Society
Paulo Moreira Vermelho, André Figueiredo Reis, Glaucia Maria Bovi Ambrosano, Marcelo Giannini
OBJECTIVES: This study aimed to evaluate the ultramorphological characteristics of tooth-resin interfaces and the bond strength (BS) of multimode adhesive systems to enamel and dentin. METHODS: Multimode adhesives (Scotchbond Universal (SBU) and All-Bond Universal) were tested in both self-etch and etch-and-rinse modes and compared to control groups (Optibond FL and Clearfil SE Bond (CSB)). Adhesives were applied to human molars and composite blocks were incrementally built up...
October 7, 2016: Clinical Oral Investigations
Yusuke Kuroda, Shingo Harada, Akinori Oonishi, Hiroki Kiyama, Yousuke Yamaoka, Ken-Ichi Yamada, Kiyosei Takasu
A catalytic strategy was developed for asymmetric substitution reactions at sp(3) -hybridized carbon atoms by using a chiral alkylating agent generated in situ from trichloroacetimidate and a chiral phosphoric acid. The resulting chiral p-methoxybenzyl phosphate selectively reacts with β-amino alcohols rather than those without a β-NH functionality. The use of an electronically and sterically tuned chiral phosphoric acid enables the kinetic resolution of amino alcohols through p-methoxybenzylation with good enantioselectivity...
October 10, 2016: Angewandte Chemie
Chris Ying Cao, Quan-Li Li
OBJECTIVE: To investigate remineralisation of dentine in the hydrogel microenvironment for the management of hypersensitivity. METHODS: Human dentine slices were prepared from extracted sound human molars. They were acid-etched with phosphoric acid and put into the polyethylene tubes. The etched dentine surfaces were covered by a 2-mm-thick layer of CaCl2 agarose hydrogel. Another 2-mm-thick layer of ion-free agarose hydrogel was added on top of the CaCl2 agarose hydrogel...
October 1, 2016: Journal of Dentistry
Nardrapee Karuna, Tina Jeoh
Cellulosic biomass is the most promising feedstock for renewable biofuel production; however, the mechanisms of the heterogeneous cellulose saccharification reaction are still unsolved. As cellulases need to bind isolated molecules of cellulose at the surface of insoluble cellulose fibrils or larger aggregated cellulose structures in order to hydrolyze glycosidic bonds, the "accessibility of cellulose to cellulases" is considered to be a reaction limiting property of cellulose. We have defined the accessibility of cellulose to cellulases as the productive binding capacity of cellulose, that is, the concentration of productive binding sites on cellulose that are accessible for binding and hydrolysis by cellulases...
October 3, 2016: Biotechnology and Bioengineering
P B DeLaune, P A Moore
Regions with long-term animal manure applications based on nitrogen (N) requirements have concerns regarding elevated nutrient levels. Most attention has focused on phosphorus (P), but heavy metal accumulation has received attention due to perceived environmental concerns. Composting is a potential management practice that can reduce total manure mass and volume while creating a stabilized product that has less odor and fewer pathogens. However, composting animal manures can lead to high N loss via ammonia volatilization and increased concentrations of nonvolatile nutrients...
September 2016: Journal of Environmental Quality
Viriya Hantrakun, Patpong Rongkard, Malinee Oyuchua, Premjit Amornchai, Cherry Lim, Vanaporn Wuthiekanun, Nicholas Pj Day, Sharon J Peacock, Direk Limmathurotsakul
: Burkholderia pseudomallei is a soil-dwelling bacterium and the cause of melioidosis, which kills an estimated 89,000 people per year worldwide. Agricultural workers are at high risk of infection due to repeated exposure. Little is known about soil physicochemical properties associated with presence or absence of the organism. Here, we evaluated the soil physicochemical properties and presence of B. pseudomallei in 6,100 soil samples collected from 61 rice fields in Thailand. The presence of B...
September 30, 2016: Applied and Environmental Microbiology
Liang Chen, Barry D Hammond, Gary Alex, Byoung In Suh
STATEMENT OF PROBLEM: Intraoral repair of porcelain or other silica-based ceramics typically requires the use of silane in the repair protocol. Some porcelain intraoral repairs also involve bonding to exposed or involved tooth tissues including dentin. A study is needed to evaluate whether the cross-contamination of dentin with silane affects bond strength to this tissue. PURPOSE: The purpose of this in vitro study was to investigate the effect of silane cross-contamination on dentin bond strength...
September 28, 2016: Journal of Prosthetic Dentistry
Gongming Zhu, Guangjun Bao, Yiping Li, Junxian Yang, Wangsheng Sun, Jing Li, Liang Hong, Rui Wang
A highly enantioselective oxidative dearomatization of naphthols with quinones catalyzed by a chiral spirocyclic phosphoric acid is described. The strategy provides concise access to enantioenriched cyclohexadienones with a quinone moiety. Remarkably, the obtained products could be easily transformed to a potentially useful dihydronaphtho[2,1-b]benzofuran scaffold.
October 21, 2016: Organic Letters
D P Lise, A Van Ende, J De Munck, Lcc Vieira, L N Baratieri, B Van Meerbeek
OBJECTIVES: To evaluate the effect of different surface treatments on the bond strength to a composite and a polymer-infiltrated ceramic CAD/CAM block after six-month artificial aging. METHODS AND MATERIALS: Two types of CAD/CAM blocks (Cerasmart, GC; Enamic, Vita Zahnfabrik) were cut in slabs of 4-mm thickness, divided into six groups, and subjected to the following surface treatments: group 1: no treatment; group 2: sandblasting (SB); group 3: SB + silane (Si); group 4: SB + Si + flowable composite (see below); group 5: 5% hydrofluoric acid etching (HF) + Si; and group 6: 37% phosphoric acid etching (H3PO4) + Si...
September 30, 2016: Operative Dentistry
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