Beneficial effects of THSG on acetic acid-induced experimental colitis: involvement of upregulation of PPAR-γ and inhibition of the Nf-Κb inflammatory pathway

The polyphenolic compound 2,3,5,4'-tetrahydroxystilbene-2-O-beta-D-glucoside (THSG) has been shown to possess anti-inflammatory effects. Here, we examined the effects of THSG on experimental mice with colitis induced by acetic acid and whether the underlying mechanisms were associated with the PPAR-γ and NF-κB pathways. Mice were randomized into six equal groups: normal, colitis model, THSG (10, 30, 60 mg·kg(-1)) and mesalazine. The mice were administered 10, 30, 60 mg·kg(-1) THSG or 100 mg·kg-1 mesalazine or saline once daily by intragastric administration for 7 days after induction of colitis by acetic acid irrigation. THSG dramatically attenuated acetic acid-induced colon lesions, including reversing the body weight loss and improving histopathological changes. THSG apparently decreased the increase of malondialdehyde (MDA) which is a marker of lipid peroxidation. THSG appears to exert its beneficial effects on acetic acid-induced experimental colitis through upregulation of PPAR-γ mRNA and protein levels and inhibition of the NF-κB pathway, which in turn decreases the protein overexpression of the downstream inflammatory mediators TNF-α, IL-6 and COX-2. The effect of THSG 60 mg·kg(-1) on PPAR-γ mRNA expression was higher than that of mesalazine. THSG may thus be a promising new candidate or lead compound for the treatment of IBD.     

Silver nanocrystals with concave surfaces and their optical and surface-enhanced Raman scattering properties

Shaped and dimpled: Silver nanocrystals enclosed by concave surfaces and thus high-index facets have been prepared by simply controlling the growth habit of Ag cubic seeds. Four types of concave nanocrystals, including octahedron, cube, octapod, and trisoctahedron, were obtained (see picture).     

The role of π electrons in the formation of benzene-containing lithium-bonded complexes

The intermolecular interactions in C₆H₆???LiX (X=OH, NH₂, F, Cl, Br, NC, CN) complexes are investigated by using second‐order Møller–Plesset perturbation theory (MP2) calculations and quantum theory of “atoms in molecules” (QTAIM) studies, and the role of π electrons is studied in the formation of these benzene‐containing lithium‐bonded complexes. The molecular electrostatic potentials of benzene and LiX determine the geometries of the lithium‐bonded complexes. The electron densities at the lithium bond critical points in the πC₆H₆???LiX complexes are obviously stronger than those in the σC₆H₆???LiX complexes, which indicates that the intermolecular interactions in the C₆H₆???LiX complexes are mainly attributable to π‐type interaction. The topological and energy properties at the lithium bond critical points in both the C₆H₆???LiX and πC₆H₆???LiX complexes are linear with the interaction energies, thereby showing the crucial role of the π electrons in the formation of these complexes. Electron localization function (ELF) analysis indicates that the formation of the lithium bonds leads to the reduction of the ELF π‐electron density and volume, and the reduction of the π‐electron volume is linear with the interaction energies with the correction coefficient 0.9949.     

Phosphotungstic acid functionalized silica nanocomposites with tunable bicontinuous mesoporous structure and superior proton conductivity and stability for fuel cells

A novel proton exchange membrane using phosphotungstic acid (HPW) as proton carrier and cubic bicontinuous Ia3d mesoporous silica (meso-silica) as framework material is successfully developed as proton exchange membranes for fuel cells. Meso-silica is functionalized by 80wt% HPW using a vacuum impregnation method. The HPW-functionalized meso-silica (HPW-meso-silica) nanocomposites are characterized by transmission electron microscopy (TEM), small angle X-ray scattering (SAXS), N(2) adsorption/desorption isotherms, thermogravimetric analysis (TGA), water uptake and four-probe conductivity. The results show that the mesoporous structure of silica hosts can be altered by the hydrothermal temperature. Conductivity measurements indicate that meso-silica host with pore diameter of 5.0 nm has the highest proton conductivity of 0.11 S cm(-1) at 80 °C and 100% relative humidity (RH) with an activation energy of ～14 kJ mol(-1) and better stability as compared to that with large mesopores. The proton conductivity and performance of HPW-meso-silica nanocomposites also increase with the RH, but it is far less sensitive to RH changes as compared to conventional perfluorosulfonic acid (PFSA) polymers such as Nafion. The maximum power density of the cell with HPW-meso-silcia nanocomposite membranes is 221 mW cm(-2) at 80 °C and 100% RH and decreases to 171 mW cm(-2) when RH is reduced to 20%, a 20% decrease in power output. In the case of a cell with Nafion 115 membranes, the decrease in power density is 95% under identical test conditions. The results demonstrate that the HPW-meso-silica nanocomposite has an exceptionally high water retention capability and is a promising proton exchange membrane material for fuel cells operating at reduced humidity and elevated temperatures.     

Titanium-capped carbon chains as promising new hydrogen storage media

The capacity of Ti-capped sp carbon atomic chains for use as hydrogen storage media is studied using first-principles density functional theory. The Ti atom is strongly attached at one end of the carbon chains via d-p hybridization, forming stable TiC(n) complexes. We demonstrate that the number of adsorbed H(2) molecules on Ti through Kubas interactions depends upon the chain types. For polyyne (n even) or cumulene (n odd) structures, each Ti atom can hold up to five or six H(2) molecules, respectively. Furthermore, the TiC(5) chain effectively terminated on a C(20) fullerene can store hydrogen with an optimal binding energy of 0.52 eV per H(2) molecule. Our results reveal a possible way to explore high-capacity hydrogen storage materials in truly one-dimensional carbon structures.     

Wetting behavior of spherical nanoparticles at a vapor-liquid interface: a density functional theory study

The wetting behavior of spherical nanoparticles at a vapor-liquid interface is investigated by using density functional theory, and the line tension calculation method is modified by analyzing the total energy of the vapor-liquid-particle equilibrium. Compared with the direct measurement data from simulation, the results reveal that the thermodynamically consistent Young's equation for planar interfaces is still applicable for high curvature surfaces in predicting a wide range of contact angles. The effect of the line tension on the contact angle is further explored, showing that the contact angles given by the original and modified Young's equations are nearly the same within the region of 60° < θ < 120°. Whereas the effect is considerable when the contact angle deviates from the region. The wetting property of nanoparticles in terms of the fluid-particle interaction strength, particle size, and temperature is also discussed. It is found that, for a certain particle, a moderate fluid-particle interaction strength would keep the particle stable at the interface in a wide temperature range.