Pore wall corrugation effect on the dynamics of adsorbed H 2 studied by in situ quasi elastic neutron scattering Observation of two timescaled diffusion

The self diffusion mechanisms for adsorbed H2 in different porous structures are investigated with in situ quasi elastic neutron scattering method at a temperature range from 50 K to 100 K and at various H2 loadings. The porous structures of the carbon materials have been characterized by sorption analysis with four different gases and the results are correlated with previous in depth analysis with small angle neutron scattering method. Thus, an investigation discussing the effect of pore shape and size on the nature of adsorbed H2 self diffusion is performed. It is shown that H2 adsorbed in nanometer scale pores is self diffusing in two distinguishable timescales. The effect of the pore, pore wall shape and corrugation on the fraction of confined and more mobile H2 is determined and analyzed. The increased corrugation of the pore walls is shown to have a stronger confining effect on the H2 motions. The difference of self diffusional properties of the two H2 components are shown to be smaller when adsorbed in smoother walled pores. This is attributed to the pore wall corrugation effect on the homogeneity of formed adsorbed layer

Ionic liquids at electrified interfaces

Until recently, “room-temperature” (<100–150 °C) liquid-state electrochemistry was mostly electrochemistry of diluted electrolytes(1)–(4) where dissolved salt ions were surrounded by a considerable amount of solvent molecules. Highly concentrated liquid electrolytes were mostly considered in the narrow (albeit important) niche of high-temperature electrochemistry of molten inorganic salts(5-9) and in the even narrower niche of “first-generation” room temperature ionic liquids, RTILs (such as chloro-aluminates and alkylammonium nitrates).(10-14) The situation has changed dramatically in the 2000s after the discovery of new moisture- and temperature-stable RTILs.(15, 16) These days, the “later generation” RTILs attracted wide attention within the electrochemical community.(17-31) Indeed, RTILs, as a class of compounds, possess a unique combination of properties (high charge density, electrochemical stability, low/negligible volatility, tunable polarity, etc.) that make them very attractive substances from fundamental and application points of view.(32-38) Most importantly, they can mix with each other in “cocktails” of one’s choice to acquire the desired properties (e.g., wider temperature range of the liquid phase(39, 40)) and can serve as almost “universal” solvents.(37, 41, 42) It is worth noting here one of the advantages of RTILs as compared to their high-temperature molten salt (HTMS)(43) “sister-systems”.(44) In RTILs the dissolved molecules are not imbedded in a harsh high temperature environment which could be destructive for many classes of fragile (organic) molecules

The suitability of infinite slit shaped pore model to describe the pores in highly porous carbon materials

The slit shaped pore model is often assumed to be the most suitable to describe the pores in micro mesoporous carbon materials. This article analyses the suitability of this assumption when pore size distribution of carbon materials is calculated applying non local density functional theory NLDFT to nitrogen adsorption isotherms. For further insight, three micro mesoporous carbide derived carbons CDC s synthesised from SiC, TiC and Mo2C, respectively, and denoted as SiC CDC, TiC CDC and Mo2C CDC, were characterized with nitrogen sorption, small angle neutron scattering SANS and Raman spectroscopy methods. Although the SANS and NLDFT with slit shaped pore model produced coinciding results for pore widths, it was found that the pores in all three carbon materials have different shapes and width to length ratios. Pores in SiC CDC can be approximated to sphere like, in TiC CDC to cylinder like and in Mo2C CDC to slit like shape. It was also suggested that the pore length may contribute significantly to the pore size distribution calculated using NLDFT model. Thus, the shape of pores in the carbon material investigated should be verified before the performance of carbon materials is explained in detail by the size and porous structure of micro mesoporous carbon material

Different Carbide Derived Nanoporous Carbon Supports and Electroreduction of Oxygen

Using rotating disc electrode technique, the oxygen reduction reaction in 0.1M KOH was studied at various micromesoporous carbide derived carbon powders, synthesized from various binary metal carbides. The catalytic activity and mechanism noticeable depends on the hierarchical structure of the nanoporous carbon electrode. The activation with CO2 increases the differential volume of pores and proportion of mesopores in carbon matrix. It was shown that the partially graphitized carbon C Mo2C with a large number of edge plane sites has higher electrocatalytic activity toward oxygen reduction in alkaline media compared with other amorphous or partly graphitized carbons studied. The corresponding relative catalytic activity of catalysts increases in the following order C WTiC2 lt; Vulcan lt; C TiC lt; C TiC A1 amp; 8804; C TiC A2 lt; C Mo2C A lt; C Mo2C

The hinge region of the scaffolding protein of cell contacts, zonula occludens protein 1, regulates interacting with various signaling proteins

Zonula occludens protein 1 (ZO-1) is a ubiquitous scaffolding protein, but it is unknown why it functions in very different cellular contacts. We hypothesized that a specific segment, the unique hinge region, can be bound by very different regulatory proteins. Using surface plasmon resonance spectroscopy and binding assays to peptide libraries, we show, for the first time, that the hinge region directly interacts with disparate signal elements such as G-proteins alpha 12 and alpha i2, the regulator of G-protein signaling 5, multifunctional signaling protein ahnak1, and L-type Ca2+-channel beta-2-subunit. The novel binding proteins specifically bound to a coiled coil-helix predicted in the hinge region of ZO-. The interactions were modulated by phosphorylation in the hinge helix. Activation of the G-proteins influenced their association to ZO-1. In colon cells, G alpha i2 and ZO-1 were associated, as shown by coimmunoprecipitation. After cotransfection in kidney cells, G alpha i2 barely colocalized with ZO-1; the colocalization coefficient was significantly increased when epinephrine activated G-protein signaling. In conclusion, proteins with different regulatory potential adhere to and influence cellular functions of ZO-proteins, and the interactions can be modulated via its hinge region and/or the binding proteins