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acid base strong ion

P Sławuta, G Sapikowski, B Sobieraj
: Buffer systems of blood and tissues, which have the ability to bind with and give up hydrogen ions, participate in maintaining the acid-base balance (ABB) of the organism. According to the classic model, the system of carbonic acid and bicarbonates, where the first component serves the role of an acid and the second a base, determines plasma pH. The so-called Stewart model, which assumes that ions in blood serum can be separated into completely dissociated - nonbuffer and not dissociated - buffer ions which may give up or accept H+ions, also describes the ABB of the organism...
September 1, 2016: Polish Journal of Veterinary Sciences
Justin A Lemkul, Alexander D MacKerell
Mg2+ ions are important in biological systems, particularly in stabilizing compact RNA folds. Mg2+ is strongly polarizing, and representing its interactions in heterogeneous environments is a challenge for empirical force field development. To date, the most commonly used force fields in molecular dynamics simulations utilize a pairwise-additive approximation for electrostatic interactions, which cannot account for the significant polarization response in systems containing Mg2+. In the present work, we refine the interactions of Mg2+ with water, Cl- ions, and nucleic acid moieties using a polarizable force field based on the classical Drude oscillator model...
October 19, 2016: Journal of Physical Chemistry. B
Katy Schäfer, Heiko Ihmels, Cornelia Bohne, Karolina Papera Valente, Anton Granzhan
It is shown by photometric and fluorimetric analysis, along with supporting theoretical calculations, that hydroxy-substituted benzo[b]quinolizinium derivatives display the characteristic features of organic photoacids. Specifically, the experimental and theoretical results confirm the strong acidity of these compounds in the excited state (pKa* < 0). The combination of the prototropic properties of the 8- and 9-hydroxybenzo[b]quinolizinium with the particular solvent-solute interactions of the excited acid and its conjugate base leads to a pronounced fluorosolvatochromism...
October 18, 2016: Journal of Organic Chemistry
Ashima Sharma, Monu Yadav, B Rajesh Kumar, P Sai Lakshman, Raju Iyenger, Gopinath Ramchandran
BACKGROUND: A major change in anesthesia practice as regards to intraoperative infusion therapy is the present requirement. Switching over to balanced fluids can substantially decrease the incidence of lactic acidosis and hyperchloremic acidosis. The deleterious effects of unbalanced fluids are more recognizable during major surgeries. We prospectively studied the influence of Sterofundin (SF) and Ringer lactate (RL) on acid-base changes, hemodynamics, and readiness for extubation during scoliosis surgery...
September 2016: Anesthesia, Essays and Researches
Tian Sheng, Yue-Feng Xu, Yan-Xia Jiang, Ling Huang, Na Tian, Zhi-You Zhou, Ian Broadwell, Shi-Gang Sun
The performance of nanomaterials in electrochemical energy conversion (fuel cells) and storage (secondary batteries) strongly depends on the nature of their surfaces. Designing the structure of electrode materials is the key approach to achieving better performance. Metal or metal oxide nanocrystals (NCs) with high-energy surfaces and open surface structures have attained significant attention in the past decade since such features possess intrinsically exceptional properties. However, they are thermodynamically metastable, resulting in a huge challenge in their shape-controlled synthesis...
October 14, 2016: Accounts of Chemical Research
Jie Hao, Tongfang Xiao, Fei Wu, Ping Yu, Lanqun Mao
In vivo monitoring of pH in live brain remains very essential to understanding acid-base chemistry in various physiological processes. This study demonstrates a potentiometric method for in vivo monitoring of pH in the central nervous system with carbon fiber-based proton-selective electrodes (CF-H+ISEs) with high anti-fouling property. The CF-H+ISEs are prepared by formation of a H+-selective membrane (H+ISM) with polyvinyl chloride polymeric matrixes containing plasticizer bis(2-ethylhexyl)sebacate, H+ ionophore tridodecylamine, and ion exchanger potassium tetrakis(4-chlorophenyl)borate onto carbon fiber electrodes (CFEs)...
October 14, 2016: Analytical Chemistry
Dieter Böning
In modern societies there is strong belief in scientific progress. But unfortunately a parallel partial regress occurs because of often evitable mistakes. Mistakes are mainly forgetting, erroneous theories, errors in experiments and manuscripts, prejudice, selected publication of "positive" results and fraud. An example for forgetting is that methods introduced decades ago are used without knowing the underlying theories: basic articles are no longer read nor cited. This omission may cause incorrect interpretation of results...
October 13, 2016: International Journal of Sports Physiology and Performance
Rong-Peng Peng, Ling-Bao Xing, Xiao-Jun Wang, Cheng-Juan Wu, Bin Chen, Hai-Feng Ji, Li-Zhu Wu, Chen-Ho Tung
We developed a novel Pb(2+)-sensor based on a microcantilever that was modified with a specific Pb(2+)-dependent DNAzyme molecule. This microcantilever sensor could detect Pb(2+) sensitively and selectively in an aqueous solution. Upon complexation with Pb(2+), the DNAzyme duplex unwinded and formed a G-quadruplex conformation, which led to an increase of repulsion between the DNAzyme molecules and a subsequent bending of the microcantilever. This microcantilever sensor could be regenerated, flowing through a strong Pb(2+) chelator, 1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid...
2016: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
Ke Li, Xiu-Xiu Lv, Lu-Lu Shi, Lu Liu, Bao-Long Li, Bing Wu
Three metal-organic frameworks (MOFs) {[Co4(OH)2(adc)6(H2O)5][Co2(OH)(btrb)]2·8H2O}n (1), {[Co4(OH)2(btrb)(nip)3(H2O)3]·4H2O}n (2·4H2O) and {[Co4(OH)2(btrb)(btc)2(H2O)2]·9H2O}n (3·9H2O) (btrb = 1,4-bis(1,2,4-triazol-4-ylmethyl)benzene, H2adc = 1,3-adamantanedicarboxylic acid, H2nip = 5-nitroisophthalic acid and H3btc = 1,3,5-benzenetricarboxylic acid) were synthesized by a hydrothermal method. 1 shows an unusual (3,4)-connected 2D network with a point symbol of (4·6(2))2(4(2)·6(2)·8(2)) based on [Co4(μ3-OH)2] and [Co2(μ3-OH)] units...
September 27, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Abhigyan Sengupta, Hsuan-Lei Sung, David J Nesbitt
In light of the current models for an early RNA-based universe, the potential influence of simple amino acids on tertiary folding of ribozymal RNA into biochemically competent structures is speculated to be of significant evolutionary importance. In the present work, the folding-unfolding kinetics of a ubiquitous tertiary interaction motif, the GAAA tetraloop-tetraloop receptor (TL-TLR), is investigated by single-molecule fluorescence resonance energy transfer spectroscopy in the presence of natural amino acids both with (e...
October 10, 2016: Journal of Physical Chemistry. B
Dongli Guan, Zhilei Chen
Proteins purified using affinity-based chromatography often exploit a recombinant affinity tag. Existing methods for the removal of the extraneous tag, needed for many applications, suffer from poor efficiency and/or high cost. Here we describe a simple, efficient, and potentially low-cost approach-split intein-mediated ultrarapid purification (SIRP)-for both the purification of the desired tagged protein from Escherichia coli lysate and removal of the tag in less than 1 h. The N- and C-fragment of a self-cleaving variant of a naturally split DnaE intein from Nostoc punctiforme are genetically fused to the N-terminus of an affinity tag and a protein of interest (POI), respectively...
2017: Methods in Molecular Biology
Guo-Xuan Wen, Min-Le Han, Xue-Qian Wu, Ya-Pan Wu, Wen-Wen Dong, Jun Zhao, Dong-Sheng Li, Lu-Fang Ma
A super-stable multifunctional terbium(iii)-organic framework, namely {[Tb(TATAB) (H2O)2]·NMP·H2O}n (Tb-MOF, H3TATAB = 4,4',4''-s-triazine-1,3,5-triyltri-m-aminobenzoic acid, NMP = N-methyl-2-pyrrolidone) was synthesized. Tb-MOF exhibits a 2D sql structure with binuclear [Tb2(COO)4(H2O)4](2+) units as 4-connected nodes, and free water and NMP molecules are inserted between 2D layers through hydrogen-bonding interactions, forming a sandwich-type architecture. Observably, such a framework remains intact in a remarkable variety of environments such as common solvents and aqueous solutions with metal cations and inorganic anions, as well as with a pH ranging from 1 to 13...
October 4, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Dominika Załubiniak, Maciej Zakrzewski, Piotr Piątek
Compounds 2 and 3 were designed and prepared as heteroditopic ion-pair receptors. The design features a 2,2-bis(aminomethyl)propionic acid core to connect and pre-organize binding groups. The cation binding is provided by a sodium selective N-acyl aza-18-crown-6 subunit whereas for anion complexation, two urea groups (receptor 2) or two squaramide groups (receptor 3) were introduced. Beyond acting as anion binding sites, the urea and squaramide groups were used to support sodium cation complexation through metal carbonyl oxygen lone pair interactions...
October 4, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Rifat Akbar, Minati Baral, B K Kanungo
Photophysical properties of a multidentate tripodal ligand, 5,5'-(2-(((8-hydroxyquinolin-5-yl) methylamino)methyl)-2-methylpropane-1,3-diyl) bis (azanediyl)bis (methylene)diquinolin-8-ol, (TAME5OX), with La(3+) and Er(3+) ions have been examined for photonics applications. The change in behavior in electronic spectra of these complexes reveals the use of TAME5OX as a sensitive optical pH based sensor to detect Ln(3+) ions whereas indication of strong green fluorescence allows simultaneous sensing within the visible region in competitive medium...
October 4, 2016: Journal of Fluorescence
Mark A Lashley, Alexander S Ivanov, Vyacheslav S Bryantsev, Sheng Dai, Robert D Hancock
Studies of the complexation of new promising ligands with uranyl (UO2(2+)) and other seawater cations can aid the development of more efficient, selective, and robust sorbents for the recovery of uranium from seawater. In this work, we propose that the ligand design principles based on structural preorganization can be successfully applied to obtain a dramatic enhancement in UO2(2+) ion binding affinity and selectivity. This concept is exemplified through the investigation of the complexes of UO2(2+), VO2(+), and VO(2+) with the highly preorganized ligand 1,10-phenanthroline-2,9-dicarboxylic acid (PDA) using a combination of fluorescence and absorbance techniques, along with density functional theory (DFT) calculations...
October 17, 2016: Inorganic Chemistry
Li Zheng, Meijuan Zhou, Zhiwei Huang, Yaxin Chen, Jiayi Gao, Zhen Ma, Jianmin Chen, Xingfu Tang
A good catalyst for efficiently controlling NOx emissions often demands strong resistance against alkali poisoning. Although the traditional ion-exchange model, based on acid-base reactions of alkalis with Brønsted acid sites, has been established over the past two decades, it is difficult to be used as a guideline to develop such an alkali-resistant catalyst. Here we establish a self-protection mechanism of deNOx catalysts against alkali poisoning by systematically studying the intrinsic nature of alkali resistance of V2O5/HWO (HWO = hexagonal WO3) that shows excellent resistance to alkali poisoning in selective catalytic reduction of NOx with NH3 (SCR)...
October 12, 2016: Environmental Science & Technology
Menglin Guo, Ping Huang, Fei Yu, Huiqing Yang, Yabin Deng, Guangxin Du, Donghui Li
Tetrasulfonated aluminum phthalocyanine (AlS4Pc), a strongly red-emitting compound, shows high detection sensitivity, little effect of photobleaching, and photochemical stability, making it an excellent red-fluorescent probe. We have observed that in acid media, a low concentration of poly-L-lysine (PLL) has a strong fluorescence-quenching effect on AlS4Pc, forming the ion-pair complex as AlS4Pc-PLL with almost no fluorescence. However, in the presence of Bi(3+), the fluorescence of AlS4Pc-PLL dramatically recovers and the emission is visual because of the remarkable recovery...
September 28, 2016: Applied Spectroscopy
Waqas Khan Kayani, Erum Dilshad, Tanveer Ahmed, Hammad Ismail, Bushra Mirza
BACKGROUND: Ajuga bracteosa has been extensively used traditionally for the treatment of a variety of diseases. The aim of the study was to scientifically validate the wide-scale exploitation of A. bracteosa in folk medicine various in vitro and in vivo assays. Moreover, these activities were related to the intrinsic biologically active phytoecdysteroids of A. bracteosa. METHODS: Aerial and root parts of A. bracteosa were first extracted separately with chloroform (AbCA and AbCR) and the residue was again extracted with methanol (AbMA and AbMR)...
September 27, 2016: BMC Complementary and Alternative Medicine
Chen Wei, Huibo Wei, Weibo Yan, Zifeng Zhao, Zelun Cai, Boxun Sun, Zhaosha Meng, Zhiwei Liu, Zuqiang Bian, Chunhui Huang
Two highly luminescent and water-soluble Eu(III) complexes, Eu1 and Eu2, based on novel carboxyl-functionalized 1,5-naphthyridine derivatives 8-hydroxy-1,5-naphthyridine-2-carboxylic acid (H2L1) and 7-cyano-8-hydroxy-1,5-naphthyridine-2-carboxylic acid (H2L2), respectively, are designed and synthesized. The crystal structure of Eu2 indicates that the central Eu(III) ion is nine-coordinated by three tridentate ligands (O^N^O). Both Eu1 and Eu2 show strong luminescence in aqueous solution with quantum yields (lifetimes) of 28% (1...
October 17, 2016: Inorganic Chemistry
Xiaolan Liu, Narasimha-Kumar Kopparapu, Yao Li, Yongping Deng, Xiqun Zheng
A fibrinolytic enzyme was produced by the medicinal mushroom, Cordyceps militaris using submerged fermentation. The enzyme was purified from culture supernatant by hydrophobic interaction, ion exchange and gel filtration chromatographies. It was purified by 36 fold, with a specific activity of 1,467.4U/mg protein and the final yield was 5.8%. The molecular weight of the enzyme as determined by SDS-PAGE and gel filtration was 28kDa and 24.5kDa, respectively, and its isoelectric point (pI) was 9.0±0.2. It was found to be a glycoprotein with carbohydrate content of 1...
September 15, 2016: International Journal of Biological Macromolecules
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