Cholesterol-induced deformation of the gramicidin A channel inhibiting potassium ion binding and transport

Gramicidin A(gA)is a kind of antibiotic peptide produced by bacillus brevis and it can dimerize across lipid bilayers to form a monovalent cation channel.In this work,we investigate the impact of cholesterol in the lipid bilayer on the binding of potassium ions with the gA channel and the transport of the ions across the channel.The results indicate that cholesterol can significantly influence the conformational stability of the gA channel and cause the channel deformation which inhibits the potassium ion binding with the channel and transport across the channel.The work provides some molecular insights into understanding of influence of lipids on the activity of gA channel in both model membranes and plasma membranes of intact cells.

Valley filtering and valley-polarized collective modes in bulk graphene monolayers

The presence of two sublattices in hexagonal graphene brings two energetically degenerate extremes in the conduction and valence bands, which are identified by the valley quantum number. Recently, this valley degree of freedom has been suggested to encode and process information, which develops a new carbon-based electronics named graphene valleytronics. In this topical review, we present and discuss valley-related transport properties in bulk graphene monolayers,which are due to strain-induced pseudomagnetic fields and associated vector potential, sublattice-stagger potential, and the valley-Zeeman effect. These valley-related interactions can be utilized to obtain valley filtering, valley spatial separation, valley-resolved guiding modes, and valley-polarized collective modes such as edge or surface plasmons. The present challenges and the perspectives on graphene valleytronics are also provided in this review.

Preparation of Cu（In,Ga）Se2 Thin Film Solar Cells by Selenization of Metallic Precursors in an Ar Atmosphere

Cu（In, Ga）Se2 thin films are deposited on Mo-coated glass substrates by Se vapour selenization of sputtered metallic precursors in the atmosphere of Ar gas flow under a pressure of about 10 Pa. The in situ heat treatment of as-grown precursor leads to the formation of a better alloy. During selenization, the growth of CuInSe2 phase preferably proceeds through Se-poor phases as CuSe and InSe at relatively low substrate temperature of 250℃, due to the absence of In2Se3 at intermediate stage at low reactor pressure. Subsequently, the Cu（In,Ga）Se2 phase is produced by the reactive diffusion of CuInSe2 with a Se-poor GaSe phase at high temperature of up to 560℃. The final film exhibits smooth surface and large grain size. The absorber is used to fabricate a glass/Mo/Cu（In, Ga）Se2/CdS/ZnO cell with the total-area efficiency of about 7%. The low open-circuit voltage value of the cell fabricated should result from the nonuniform distribution of In and Ga in the absorber, due to the diffusion-controlled reaction during the phase formation. The films, as well as devices, are characterized.

Nonlinear Shift of the Raman A1 Mode in Ga-Incorporated CuInSe2 Thin Films

Composition dependence of quaternary CuIn1-x GaxSe2 films on Ga content has been systematically investigated by Raman scattering. The dominant A1 mode shifts from 174cm^-1 for CuInSe2 to 185cm^-1 for CuGaSe2 in an approximately polynomial curve other than a linear curve, indicating existence of asymmetric distribution of Ga and In on a microscopic scale in films. With Ga content x 〉 0.3, the significantly broadening and intensity decrease of A1 modes suggest the degradation of crystalline quality of chalcopyrite phase. Additionally, the quenching of additional Raman band at 183cm^-1 for the Ga-rich films reveals that CuAu-ordered phase can coexist in nominal chalcopyrite CuInSe2 films but not in CuGaSe2, due to Ga inhibition effect.

Influence of the total gas flow rate on high rate growth microcrystalline silicon films and solar cells

This paper reports that high-rate-deposition of microcrystalline silicon solar cells was performed by very-highfrequency plasma-enhanced chemical vapor deposition. These solar cells, whose intrinsic μc-Si：H layers were prepared by using a different total gas flow rate （Ftotal）, behave much differently in performance, although their intrinsic layers have similar crystalline volume fraction, opto-electronic properties and a deposition rate of - 1.0 nm/s. The influence of Ftotal on the micro-structural properties was analyzed by Raman and Fourier transformed infrared measurements. The results showed that the vertical uniformity and the compact degree of μc-Si：H thin films were improved with increasing Ftotal. The variation of the microstructure was regarded as the main reason for the difference of the J V parameters. Combined with optical emission spectroscopy, we found that the gas temperature plays an important role in determining the microstructure of thin films. With Ftotal of 300 sccm, a conversion efficiency of 8.11% has been obtained for the intrinsic layer deposited at 8.5 A/s （1 A=0.1 nm）.

Crystallization of μc-Si on plastic substrate by using a pulsed double-frequency YAG laser

thin film transistors(TFTs) of microcrystalline silicon(μc-Si) can provide higher mobility and stability than that of a-Si and better uniformity than that of poly-Si TFTs,and it would be more suitable to be applied to larger-area AMOLEDs. By using 2wYAG laser annealing,crystalline μc-Si thin film on plastic substrate has been investigated and the proper laser energy needed for crystallization has been indicated. It has been found that the dehydrogenation process at 300-450 oC for a few of hours could be omitted by decreasing the H content in the crystallization precursor,which is suitable for laser crystallization on plastic substrates. The crystalline volume fraction(Xc) and the grain size of the resulted μc-Si could be adjusted by controlling the laser energy. By this method,the μc-Si on plastic substrate with Xc and grain size is respectively 85%(at the maximum) and 50 nm.

Thermal analysis and Joule-Thomson expansion of black hole exhibiting metric-affine gravity

This study examines a recently hypothesized black hole,which is a perfect solution of metric-affine gravity with a positive cosmological constant,and its thermodynamic features as well as the Joule-Thomson expansion.We develop some thermodynamical quantities,such as volume,Gibbs free energy,and heat capacity,using the entropy and Hawking temperature.We also examine the first law of thermodynamics and thermal fluctuations,which might eliminate certain black hole instabilities.In this regard,a phase transition from unstable to stable is conceivable when the first law order corrections are present.In addition,we study the efficiency of this system as a heat engine and the effect of metric-affine gravity for the physical parameters q_(e),q_(m),κ_(s),κ_(d),and κ_(sh).Further,we study the Joule-Thomson coefficient and inversion temperature,and observe the isenthalpic curves in the Ti−Pi plane.In metric-affine gravity,a comparison is made between a van der Waals fluid and a black hole to study their similarities and differences.

Composition-induced structural modifications in the quaternary CuIn1-xGaxSe2 thin films： bond properties versus Ga content

In this paper the dependence of structural properties of the quaternary CuIn1-xGaxSe2 films with tetragonal structure on the Ga content has been systematically investigated by Raman scattering and x-ray diffraction spectra. The shift of the dominant A1 mode, unlike the lattice constants, does not follow the linear Vegard law with increasing Ga content x, whereas exhibits approximately polynomial change from 174 cm^-1 for CuInSe2 to 185 cm^-1 for CuGaSe2. Such behaviour should be indicative of presence of the asymmetric distribution of Ga and In on a microscopic scale in the films, due to Ga addition. The changes in the tetragonal distortion η lead to a significant variation in the anion displacement parameter U, which should be responsible for the evolution of bond parameters and resultant Raman bands with x.

Optimization of n/i and i/p buffer layers in n-i-p hydrogenated microcrystalline silicon solar cells

Hydrogenated microcrystalline silicon （μc-Si：H） intrinsic films and solar cells with n-i-p configuration were prepared by plasma enhanced chemical vapor deposition （PECVD）. The influence of n/i and i/p buffer layers on the μc-Si：H cell performance was studied in detail. The experimental results demonstrated that the efficiency is much improved when there is a higher crystallinity at n/i interface and an optimized a-Si：H buffer layer at i/p interface. By combining the above methods, the performance of μc-Si：H single-junction and a-Si：H/μc-Si：H tandem solar cells has been significantly improved.

An integrated driving circuit implemented with p-type LTPS TFTs for AMOLED

Based on the technology of low temperature poly silicon thin film transistors (poly-Si-TFTs), a novel p-type TFT AMOLED panel with self-scanned driving circuit is introduced in this paper. A shift register formed with novel p-type TFTs is pro- posed to realize the gate driver. A flip-latch cooperated with the shift register is designed to conduct the data writing. In order to verify the validity of the proposed design, the circuits are simulated with SILVACO TCAD tools, using the MODEL in which the parameters of LTPS TFTs were extracted from the LTPS TFTs made in our lab. The simulation results indicate that the circuit can fulfill the driving function.