Ultra-stable Pt cathode catalysts in ultra-low Pt loading proton exchange membrane fuel cells were synthesized by facile carbon encapsulation.

We have studied the adsorption and dissolution phenomena of sodium halide salts (NaF, NaCl, and NaBr) at the surface of amorphous D 2 O-ice films for the temperature range 105-140 K by the techniques of lowenergy sputtering, reactive ion scattering, and temperature-programmed desorption mass spectrometry. These salts readily dissociate to ions at the ice surface. The dissociated Na + and Fions migrate from the surface to the interior at temperatures above 125 K, while Cland Brions stay at the surface, leading to the spatial separation of ions near the ice surface. Brshows a slightly higher propensity for residing at the surface than Cl -, most likely due to its less efficient solvation by surface water molecules. The ion separation process is driven by thermodynamic forces specific to the ions. The speed of ion migration depends strongly on ice temperature, indicating that the ion motion is limited by the diffusion of water molecules.

The InTe has intrinsically low lattice thermal conductivity κL originating from the anharmonic bonding of In1+ ion in the lattice, which scatters the phonons. Here we report the enhancement of thermoelectric properties in Te-deficient InTe1−δ (δ = 0, 0.01, 0.1, and 0.2) polycrystalline compounds by lattice softening and energy band gap opening. Te-deficiency gives rise to more weak chemical bonding between In1+ atoms and In3+Te2− clusters than those of pristine InTe, resulting in the reduction of κL near the room temperature. The weak ionic bonding is confirmed by the increase of lattice volume from the X-ray diffraction and lattice softening by the decrease of Debye temperature with increasing Te-deficiency. We observed the low lattice thermal conductivity κL of 0.53 W m−1 K−1 at 300 K for InTe0.99, which is about 25 % decreased value than those of InTe. The Te-deficiency also induces energy band gap so that the electrical resistivity and Seebeck coefficient are increased due to the decrease of carrier concentration. Temperature-dependent thermoelectric properties shows the high Seebeck coefficient at high temperature and high electrical conductivity near room temperature, resulting in the temperature-insensitive high power factor S2σ over a wide temperature range. Owing to the temperature-insensitive high power factor and intrinsic low lattice thermal conductivity by Te-deficiency, the thermoelectric performances of figure-of-merit ZT and engineering ZTeng are enhanced at mild temperature range (≤550 K).

PurposeWith the significance of stable adhesion of alveolar bone and peri-implant soft tissue on the surface of titanium for successful dental implantation procedure, the purpose of this study was to apply microgrooves on the titanium surface and investigate their effects on peri-implant cells and tissues.MethodsThree types of commercially pure titanium discs were prepared; machined-surface discs (A), sandblasted, large-grit, acid-etched (SLA)-treated discs (B), SLA and microgroove-formed discs (C). After surface topography of the discs was examined by confocal laser scanning electron microscopy, water contact angle and surface energy were measured. Human gingival fibroblasts (hGFs) and murine osteoblastic cells (MC3T3-E1) were seeded onto the titanium discs for immunofluorescence assay of adhesion proteins. Commercially pure titanium implants with microgrooves on the coronal microthreads design were inserted into the edentulous mandible of beagle dogs. After 2 weeks and 6 weeks of implant insertion, the animal subjects were euthanized to confirm peri-implant tissue healing pattern in histologic specimens.ResultsGroup C presented the lowest water contact angle (62.89±5.66 θ), highest surface energy (45±1.2 mN/m), and highest surface roughness (Ra=22.351±2.766 µm). The expression of adhesion molecules of hGFs and MC3T30E1 cells was prominent in group C. Titanium implants with microgrooves on the coronal portion showed firm adhesion to peri-implant soft tissue.ConclusionsMicrogrooves on the titanium surface promoted the adhesion of gingival fibroblasts and osteoblastic cells, as well as favorable peri-implant soft tissue sealing.Graphical Abstract