The objective was to study the effect of phosphate salts and fixation solutions on the proton dynamics in articular cartilage in vitro. Microscopic magnetic resonance imaging (μMRI) T(2) anisotropy and nuclear magnetic resonance (NMR) double quantum-filtered (DQF) spectroscopy were used to study the full-thickness articular cartilage from several canine humeral heads. The in-plane pixel size ac...

proton exchange membrane fuel cells (pemfcs) are electrochemical devices that show the highest power densities compared to the other type of fuel cell. in this work, nanocomposite membranes used for proton exchange membrane fuel cells as poly(vinyl alcohol)/la2ce2o7 (pva-lc) with the aim of increasing the water uptake and proton conductivity. glutaraldehyde (ga) was used as cross linking agent ...

Human oxyhemoglobin showed a biphasic autoxidation curve containing two rate constants, i.e. kf for the fast autoxidation due to the alpha chains, and ks for the slow autoxidation of the beta chains, respectively. Consequently, the autoxidation of the HbO2 tetramer produces two different curves from the pH dependence of kf and ks. The analysis of these curves revealed that the beta chain of the...

New proton exchange membrane (PEM) materials with high proton conductivities at elevated temperatures (ca. > 150 °C) offer the promise of improving PEM fuel cell operation. Higher operating temperatures would provide several benefits including: (i) improved resistance to carbon monoxide poisoning of the platinum (Pt) electrocatalyst at the anode, (ii) reduced need for feed-stream heat and humid...

The dicyclohexylcarbodiimide (DCCD)-binding proteolipid of the chloroplast ATPase complex was solubilized in 1-butanol, isolated by ion exchange chromatography, and reconstituted in a liposomal system. Proton-conducting activity was monitored by fluorometry with 9-aminoacridine as an indicator of delta pH in K+-loaded liposomes suspended in a K+-free medium. Addition of valinomycin served to cr...

An inorganic proton exchange membrane based on sintered mesoporous silica and phosphoric acid was developed with a high proton conductivity of 0.06 S cm(-1) at 200 °C, achieving an excellent power output of 689 mW cm(-2) in H2 at 190 °C and 200 mW cm(-2) in methanol at 200 °C with no external humidification.

The exchange of deuterium for hydrogen in water often produces solvent kinetic isotope effects (KSIEs) on the rate constants associated with enzyme reactions, including those catalyzed by RNA. Recently, KSIEs have been used to show that proton transfer occurs in the rate-limiting step of cleavage by the hepatitis delta virus (HDV) ribozyme and other catalytic RNAs. To test the underlying assump...

The general acid/base catalyzed cleavage of a number of alkyl esters of uridine-3'- (and -5'-)phosphate has been studied by utilizing a cleaving agent, in which the catalytic moiety (a substituted 1,3,5-triazine) is tethered to an anchoring Zn(II):cyclen moiety. Around pH 7, formation of a strong ternary complex between uracil, Zn(II) and cyclen brings the general acid/base catalyst close to th...

Understanding mechanisms of (+)-anti-BPDE detoxification is crucial for combating its mutagenic and potent carcinogenic action. However, energetic-structural correlations of reaction intermediates and transition states during detoxification via hydrolysis are poorly understood. To gain mechanistic insight we have computationally characterized intermediate and transition species associated with ...