Explicit solutions of Boussinesq--Burgers equation

Darboux transformation with multi-parameters for the Boussinesq--Burgers (B--B) equation is derived. For an application, some important explicit solutions of the B--B equation are obtained, including 2N-soliton solution and periodic solution. Finally, some elegant and interesting figures are plotted.     

The pertinence of expression of heat shock proteins (HSPs) to the efficacy of cryopreservation in HELAs

HELAs (Hela cells, passed cells of human cervical carcinoma) were heat or cold treated (named heat or cold shock) and then resumed normal culture for 2, 4 or 8 hours respectively. The expressions of heat shock protein 70 (HSP70) and 90 (HSP90) of the HELAs were measured by Northern and Western blotting. HELAs after 4-hour culture were exposed to or cryopreserved with different concentration of dimethyl sulfoxide (Me2SO, 2.5%, 5%, 10%, 15% and 20% respectively, V/V). Meanwhile, the HELAs after different culture time (2, 4 and 6 hours of culture) were cryopreserved with 5% Me2SO. After exposure or cryopreservation, the number of live HELAs was counted and the survival rate was calculated. The results showed that heat shock increased the expression of HSP70 and HSP90 of HELAs, while cold shock decreased the expression of the two proteins. When the concentrations of Me2SO were 10%, 15% and 20%, the survival rates of HELAs after exposure to Me2SO or cryopreservation were much lower than those when the concentrations were small. The survival rates of the heat shocked HELAs were significantly higher than those of the cold shocked and control HELAs. After cryopreservation with 5% Me2SO, the survival rate of heat shocked HELAs group with 2 hours culture time was the lowest among all the groups of HELAs with different cultural time. From the results of this study, we conclude that the expressions of HSP70 and HSP90 in HELAs increased significantly after heat shock, while cold shock decreased the expressions of these two proteins. The over-expressions of HSPs in the heat shocked HELAs could protect the cells from both injury caused by potential toxicity of high concentrations of Me2SO and cryoinjury caused by the freeze-thawing/cryopreservation procedure.     

Synthesis,formation mechanism and electric property of hollow InP nanospheres

The present work reports on novel four-layer thermally driven piezoresistive cantilevers implemented in one- and two-dimensional arrays for parallel proximity scanning. There, the heater (metallic meander), the piezoresistive deflection sensor, and the metal actuation film with significantly higher thermal expansion coefficient make up separate layers. Actuation efficiency and cross-talk of the novel cantilever design are studied and compared with two recent designs: thin metallic film and ion-implanted heater. The novel actuator, integrated on a 240 μm long and 3 μm thick silicon cantilever and supplied by V _dc=1 V enables deflections up to 5 μm of the AFM-tip with an actuation efficiency of about 170 nm/mW and suppressed cross-talk between actuator and sensor.     

Multiplesite structure and photoluminescence properties of Eu3+ doped MgO nanocrystals

MgO:Eu³⁺ nanocrystals with average diameter around 15 nm were prepared via a facile combustion method under a weak reductive atmosphere at temperature as low as 300°C. The photoluminescence spectra showed that the MgO:Eu³⁺ nanocrystals emit white light, the hypersensitive transition (⁵ D ₀→⁷ F _j of Eu³⁺) emission was prominent in the emission spectra resulting from the noinversion symmetry local site at which Eu³⁺ ions were located. Two kinds of luminescence sites of Eu³⁺ are identified by means of the fluorescence decay and site-selective spectroscopy. The excitation and absorption spectra indicated that the absorption of surface state decreased with the increase of Eu³⁺ concentration, meaning that the surface defect decreased through Eu³⁺ doping for some of them located at the disordered sites near the surface or absorbed at the surface of MgO host. Meanwhile, absorptivity and CIE chromaticity coordinates of all samples were measured; the results were in accordance with the excitation and absorption spectra and photoluminescence spectra, respectively.     

Controlled growth of uniform nanoflakes-built pyrite FeS<Subscript>2</Subscript> microspheres and their electrochemical properties

Nanoflakes-built pyrite FeS₂ microspheres were synthesized through a simple solvothermal process in mixed solvents of N, N-dimethytformamide and ethylene glycol without using any surfactant. Both the composition of the solvents and urea were key factors for the formation of the uniform products. It was found that the flake-like intermediate products transformed into FeS₂ nanoflakes in situ in the early stage and Ostwald ripening growth mechanism would contribute to the uniformity of the final products. Electrochemical studies revealed that the nanoflakes-built pyrite FeS₂ microspheres exhibited large lithium storage capacities. This method can be easily controlled and is expected to be extendable to the fabrication of other metal chalcogenides with controlled shape and structure.     

Adsorption and dissociation of O2 on the Cu2O(1 1 1) surface: Thermochemistry, reaction barrier

The adsorption and dissociation of O₂ on the perfect and oxygen-deficient Cu₂O(1 1 1) surface have been systematically studied using periodic density functional calculations. Different kinds of possible modes of atomic O and molecular O₂ adsorbed on the Cu₂O(1 1 1) surface are identified: atomic O is found to prefer threefold 3Cu site on the perfect surface and O_vacancy site on the deficient surface, respectively. Cu_CUS is the most advantageous site with molecularly adsorbed O₂ lying flatly over singly coordinate Cu_CUS-Cu_CSA bridge on the perfect surface. O₂ adsorbed dissociatively on the deficient surface, which is the main dissociation pathway of O₂, and a small quantity of molecularly adsorbed O₂ has been obtained. Further, possible dissociation pathways of molecularly adsorbed O₂ on the Cu₂O(1 1 1) surface are explored, the reaction energies and relevant barriers show that a small quantity of molecularly adsorbed O₂ dissociation into two O atoms on the deficient surface is favorable both thermodynamically and kinetically in comparison with the dissociation of O₂ on the perfect surface. The calculated results suggest that the presence of oxygen vacancy exhibits a strong chemical reactivity towards the dissociation of O₂ and can obviously improve the catalytic activity of Cu₂O, which is in agreement with the experimental observation.     

CH4 dissociation on NiCo (1 1 1) surface: A first-principles study

A density-functional theory method has been conducted to investigate the adsorption of CH_x (x = 0-4) as well as the dissociation of CH_x (x = 1-4) on (1 1 1) facets of ordered NiCo alloy. The results have been compared with those obtained on pure Ni (1 1 1) surface. It shows that the adsorption energies of C and CH are decreased while it is increased for CH₃ on NiCo (1 1 1) compared to those on pure Ni (1 1 1). Furthermore, on NiCo (1 1 1), dissociation of CH_x prefers not to the top of Ni, but to the top of Co. The rate-determining step for CH₄ dissociation is considered as the first step of dehydrogenation on NiCo (1 1 1), while it is the fourth step of dehydrogenation on Ni (1 1 1). Furthermore, the activation barrier in rate-determining step is slightly higher by 0.07 eV on Ni (1 1 1) than that on NiCo (1 1 1). From above results, it is important to point out that carbon is easy to form on NiCo (1 1 1) although the adsorption energy of C atom is slightly decreased compared to that on Ni (1 1 1).     

Optical spin-dependent angular shift in structured metamaterials

The physics behind the spin (polarization)-dependent electromagnetic hot-spot phenomenon is due to the presence of the geometric phase resulting from the optical spin-orbit interaction in the interaction of light with the subwavelength microstructures. Unlike the tiny spin-dependent shift of light associated with the usual spin-Hall effect of light, here we present the distinct polarization-dependent angular shift by employing an array of subwavelength metallic apertures. More importantly, this novel electromagnetic precession is accompanied by the extraordinary optical transmission phenomenon and offers the exciting possibilities for novel applications for subwavelength structured metallic systems.     

InN thin film lattice dynamics by grazing incidence inelastic x-ray scattering

Achieving comprehensive information on thin film lattice dynamics so far has eluded well established spectroscopic techniques. We demonstrate here the novel application of grazing incidence inelastic x-ray scattering combined with ab initio calculations to determine the complete elastic stiffness tensor, the acoustic and low-energy optic phonon dispersion relations of thin wurtzite indium nitride films. Indium nitride is an especially relevant example, due to the technological interest for optoelectronic and solar cell applications in combination with other group III nitrides.