Boc-L-thiaproline

Pradefovir, a prodrug of PMEA, is under phase 2 clinical trial in China to evaluate its pharmacokinetic and pharmacodynamics after multiple-dose study, with adefovir dipivoxil and tenofovir disoproxil fumarate as positive control. A rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of pradefovir, PMEA and tenofovir in HBV patient serum. Serum samples were pretreated via simple protein precipitation with methanol and entecavir was used as internal standard. Chromatographic separation was carried out on a Synergi® fusion-RP column (150mm×4.6mm) by gradient elution with methanol and 0.1% formic acid in water (v/v) at a flow rate of 1mL/min. The analytes were detected in multiple reaction monitoring mode with positive ion electrospray ionization at m/z 424.1/151.0, 274.1/162.2, 288.1/176.1, and 278.1/152.2for pradefovir, PMEA, tenofovir and IS, respectively.

The condensational growth of a water droplet follows water vapor accommodation and is described by the mass accommodation coefficient, α. To determine α for droplets coated by straight chain and branched alcohols, we perform molecular dynamics simulations with umbrella sampling and direct impinging. The free energy profiles of water from gas phase to bulk water coated by organic are estimated by the former method. These free energy profiles exhibit a barrier to accommodation in the monolayers containing alcohols with zero and one-level of branching. However, the barrier is not observed for monolayers containing alcohols with two-levels of branching. These profiles and friction coefficients estimated from simulation are used to calculate α from transition state and Grote-Hynes theory. Results are compared with sticking probabilities estimated from direct impinging simulations, and their differences are interpreted through processes included in each theory.

The oxygen reduction reaction is of major importance in energy conversion and storage. Controlling electrocatalytic activity and its selectivity remains a challenge of modern electrochemistry. Here, first principles calculations and analysis of experimental data unravel the mechanism of this reaction on Au-Pd nanoalloys in acid media. A mechanistic model is proposed from comparison of the electrocatalysis of oxygen and hydrogen peroxide reduction on different Au-Pd ensembles. A H2O production channel on contiguous Pd sites proceeding through intermediates different from H2O2 and OOHσ adsorbate is identified as the bifurcation point for the two reaction pathway alternatives to yield either H2O or H2O2. H2O2 is a leaving group, albeit reduction of H2O2 to H2O can occur by electrocatalytic HO-OH dissociation that is affected by the presence of adsorbed OOHσ. Similarities and differences between electrochemical and direct synthesis from H2 + O2 reaction on Au-Pd nanoalloys are discussed.

Organo-metal halide perovskite is an efficient light harvester in photovoltaic solar cells. Organometal halide perovskite is used mainly in its "bulk" form in the solar cell. Confined perovskite nanostructures could be a promising candidate for efficient optoelectronic devices, taking advantage of the superior bulk properties of organo-metal halide perovskite, as well as the nanoscale properties. In this paper, we present facile low temperature synthesis of two-dimensional (2D) lead halide perovskite nanorods (NRs). These NRs show a shift to higher energies in the absorbance and in the photoluminescence compared to the bulk material, which supports their 2D structure. X-ray diffraction (XRD) analysis of the NRs, demonstrates their 2D nature combined with the tetragonal 3D perovskite structure. In addition, by alternating the halide composition, we were able to tune the optical properties of the NRs. Fast Fourier Transform, and electron diffraction show the tetragonal structure of these NRs.