Preparation and evaluation of poly(polyethylene glycol methyl ether acrylate-co-polyethylene glycol diacrylate) monolith for protein analysis

A poly(polyethylene glycol methyl ether acrylate-co-polyethylene glycol diacrylate) monolith was prepared by UV-initiated polymerization. Methanol and ethyl ether were selected as porogens from a variety of organic solvents to achieve the desirable characteristics of the monolith. The preparation of the monolith could be achieved within 10 min. The monolith was macroscopically homogeneous, had low flow resistance, and did not swell or shrink significantly in tetrahydrofuran. Inverse size-exclusion data indicate that the monolith had a total porosity of 75.4% and an internal porosity of 9.1%. The monolith could be used for size-exclusion separation of peptides, although it could not separate proteins with molecular masses between 10 and 100 K due to its unique pore size distribution. It was found to resist adsorption of proteins in capillary liquid chromatography when using 100 mM phosphate buffer (pH 7.0) containing 0.5 M NaCl. Complete recovery of both acidic and basic proteins was achieved. The monolith can be used for applications in which inert materials are required for protein analysis.     

Toward cocaine esterase therapeutics

Cocaine is among the most reinforcing of all drugs of abuse, yet no effective pharmacotherapy is available. Herein, we report the development and characterization of phage-displayed cocaine esterases with pharmacologically relevant kinetic parameters (kcat/Km approximately 104 M-1 s-1).     

Liquid hydrogen in protonic chabazite

Due to its fully reversible nature, H(2) storage by molecular adsorption could represent an advantage with respect to dissociative processes, where kinetic effects during the charging and discharging processes are present. A drawback of this strategy is represented by the extremely weak interactions that require low temperature and high pressure. High surface area materials hosting polarizing sites can represent a viable way toward more favorable working conditions. Of these, in this contribution, we have studied hydrogen adsorption in a series of zeolites using volumetric techniques and infrared spectroscopy at 15 K. We have found that in H-SSZ-13 zeolite the cooperative role played by high surface area, internal wall topology, and presence of high binding energy sites (protons) allows hydrogen to densify inside the nanopores at favorable temperature and pressure conditions.     

Effects of lung volume on vertical larynx position during phonation

The vertical position of the larynx seems to be relevant to voicefunction. As a high vertical larynx position is often seen in hyperfunctional and strained voices, a lowering of a habitually elevated larynx is sometimes a specific goal in clinical voice therapy and different larynx-lowering exercises are used to achieve this goal. Earlier investigations have shown that pitch and to some extent also vocal loudness are relevant to vertical larynx position. In the present investigation, we examine if lung volume affects vertical larynx position. Using a multi-channel electroglottograph, the larynx position was measured in 29 healthy, vocally untrained subjects, who phonated at different lung volumes, pitches, and degrees of vocal loudness. The main results were that high lung volume was clearly associated with a lower larynx position as compared to low lung volume. In addition, vertical larynx position was strongly correlated with pitch. Both of these dependencies were shown to be stronger in males than in females. Our results suggest that lung volume is a factor that is highly relevant to larynx height in untrained subjects.     

Mechanistic investigation on the hydrogenation of imines by[p-(Me2CH)C6H4Me]RuH(NH2CHPhCHPhNSO2C6H4-p-CH3). Experimental support for an ionic pathway

The need for acidic activation in the stoichiometric hydrogenation of benzyl-[1-phenyl-ethylidene]-amine (6a) or [1-(4-methoxy-phenyl)-ethylidene]-methyl-amine (6b) by Noyori's catalyst [p-Me2CH)C6H4Me]RuH(NH2CHPhCHPhNSO2C6H4-p-CH3) (2) is inconsistent with the proposed concerted mechanism and supports an ionic mechanism.     

A general route to protected quaternary alpha-amino acids from beta-amino alcohols via a stereocontrolled radical approach

A radical-based approach facilitates the highly stereocontrolled functionalisation of beta-amino alcohols, opening up a new, generally applicable methodology for the preparation of quaternary alpha-amino acids.     

Interpretation of unusual absorption bandwidths and resonance Raman intensities in excited state mixed valence

Excited state mixed valence (ESMV) occurs in molecules in which the ground state has a symmetrical charge distribution but the excited state possesses two or more interchangeably equivalent sites that have different formal oxidation states. Although mixed valence excited states are relatively common in both organic and inorganic molecules, their properties have only recently been explored, primarily because their spectroscopic features are usually overlapped or obscured by other transitions in the molecule. The mixed valence excited state absorption bands of 2,3-di-p-anisyl-2,3-diazabicyclo[2.2.2]octane radical cation are well-separated from others in the absorption spectrum and are particularly well-suited for detailed analysis using the ESMV model. Excited state coupling splits the absorption band into two components. The lower energy component is broader and more intense than the higher energy component. The absorption bandwidths are caused by progressions in totally symmetric modes, and the difference in bandwidths is caused by the coordinate dependence of the excited state coupling. The Raman intensities obtained in resonance with the high and low energy components differ significantly from those expected based on the oscillator strengths of the bands. This unexpected observation is a result of the excited state coupling and is explained by both the averaging of the transition dipole moment orientation over all angles for the two types of spectroscopies and the coordinate-dependent coupling. The absorption spectrum is fit using a coupled two-state model in which both symmetric and asymmetric coordinates are included. The physical meaning of the observed resonance Raman intensity trends is discussed along with the origin of the coordinate-dependent coupling. The well-separated mixed valence excited state spectroscopic components enable detailed electronic and resonance Raman data to be obtained from which the model can be more fully developed and tested.     

Some ergodic and rigidity properties of discrete Heisenberg group actions

The goal of this paper is to study ergodic and rigidity properties of smooth actions of the discrete Heisenberg group \(\mathcal{H}\). We establish the decomposition of the tangent space of any C^∞ compact Riemannian manifold M for Lyapunov exponents, and show that all Lyapunov exponents for the central elements are zero. We obtain that if an \(\mathcal{H}\) action contains an Anosov element, then under certain conditions on the eigenvalues of this element, the action of each central element is of finite order. In particular, there is no faithful codimension one Anosov Heisenberg group action on any compact manifold, and there is no faithful codimension two Anosov Heisenberg group action on tori. In addition, we show smooth local rigidity for higher rank ergodic \(\mathcal{H}\) actions by toral automorphisms, using a generalization of the KAM (Kolmogorov–Arnold–Moser) iterative scheme.     

Defect chemistry, surface structures, and lithium insertion in anatase TiO2

Atomistic simulation techniques are used to investigate the defect properties of anatase TiO(2) and Li(x)TiO(2) both in the bulk and at the surfaces. Interatomic potential parameters are derived that reproduce the lattice constants of anatase, and the energies of bulk defects and surface structures are calculated. Reduction of anatase involving interstitial Ti is found to be the most favorable defect reaction in the bulk, with a lower energy than either Frenkel or Schottky reactions. The binding energies of selected defect clusters are also presented: for the Ti(3+)-Li(+) defect cluster, the binding energy is found to be approximately 0.5 eV, suggesting that intercalated Li ions stabilize conduction band electrons. The Li ion migration path is found to run between octahedral sites, with an activation energy of 0.45-0.65 eV for mole fractions of lithium in Li(x)TiO(2) of x < or = 0.1. The calculated surface energies are used to predict the crystal morphology, which is found to be a truncated bipyramid in which only the (101) and (001) surfaces are expressed, in accord with the available microscopy data. Calculations of defect energies at the (101) surface suggest that single Ti(3+) defects and neutral Ti(3+)-Li(+) pairs tend to segregate to the surface.