Preparation of Cu(In,Ga)(S,Se)2 thin films by sequential evaporation and annealing in sulfur atmosphere

Cu(In,Ga)(S,Se)₂ thin films with high Ga/III ratio (around 0.8) were prepared by sequential evaporation from CuGaSe₂, CuInSe₂, In₂Se₃ and Ga₂Se₃ compounds and then annealing in H₂S gas atmosphere. The annealing temperature was varied from 400 to 500 °C. These samples were characterized by means of XRF, EPMA, XRD and SEM. The S/(S+Se) mole ratio in the thin films increased with increase in the annealing temperature, keeping the Cu, In and Ga contents nearly constant. The open circuit voltage increased and the short circuit current density decreased with increase in the annealing temperature. The best solar cell using Cu(In,Ga)(S,Se)₂ thin film with Ga/(In+Ga)=0.79 and S/(S+Se)=0.11 annealed at 400 °C demonstrated V_oc=535 mV, I_sc=13.3 mA/cm², FF=0.61 and efficiency=4.34% without AR-coating.     

Measurement and correlation of mutual diffusion coefficients for styrene-butadiene rubber(SBR)-n-nonane systems

The mutual diffusion coefficients for styrene-butadiene rubber(SBR)-n-nonane systems were measured using a sorption apparatus with a quartz spring at 100 and 130°C for mass fractions of n-nonane ranging from 0 to 0.16. The mutual diffusion coefficients were correlated with good agreement by the free-volume theory.     

A new sparse design framework for broadband power amplifier behavioral modeling and digital predistortion

In this paper, we propose a new sparse framework for the design of the behavioral model and digital predistorter of a broadband power amplifier (PA). We start by formulating the Volterra kernel to multidimensional memory polynomial by considering the high‐order dynamic truncation of the Volterra model. Then we show how an estimate of the most significant coefficients may be obtained using a matching pursuit (MPT) algorithm by exploiting the sparsity of the model. After the indices of the nonzero coefficients are roughly estimated, the block exact Householder inverse QR‐decomposition‐based recursive least squares (HIQRD‐RLS) algorithm is utilized to estimate the sparse model complex coefficients. For broadband nonlinear PAs, the proposed approach is demonstrated to achieve the best performance among the well‐known traditional approaches in terms of in‐band and out‐of‐band specifications. The proposed approach is also validated by evaluating the digital predistortion (DPD) performance on a Class‐AB PA in terms of adjacent channel power ratio (ACPR). © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Multifunctional Initiator with Platinum-Acetylide Dendritic Core for Living Polymerization of Isocyanides

A novel multifunctional initiator has been developed by peripheral modification of a Pt-acetylide dendrimer. Pd–Pt μ-ethynediyl units were introduced to the first-generation dendrimer by a divergent method. The dendritic initiator was applicable to the living polymerization of aryl isocyanides, producing high molecular weight polymers with a narrow polydispersity index in quantitative yields. The ³¹P NMR spectrum of the resulting polymer suggested that all Pd–Pt μ-ethynediyl units in the dendritic molecule actually functioned as an initiator.     

Thin films of Cu(In,Ga)Se2 and ordered vacancy compound prepared by thermal crystallization and their photovoltaic applications

Thin films of Cu–In–Ga–Se alloy system with various composition were prepared by thermal crystallization from In/CuInGaSe/In precursor. Electron probe microanalysis and X-ray diffraction study revealed that these samples were assigned to chalcopyrite Cu(In,Ga)Se₂ or ordered vacancy compound Cu(In,Ga)₂Se_3.5. Solar cell with ZnO:Al/i–ZnO/CdS/Cu(In,Ga)Se₂/Mo/soda-lime glass substrate structure was fabricated by using thermal crystallization technique, and demonstrated a 9.58% efficiency without AR-coating.     

Conformational properties of the guanine-binding site of ribonuclease T1 inferred from the X-ray structure and protein engineering

Recognition by ribonuclease T₁ of guanine bases via multidentatehydrogen bonding and stacking interactions appears to be mediatedmainly by a short peptide segment formed by one stretch of aheptapeptide, Tyr⁴²-Asn⁴³-Asn⁴⁴-Tyr⁴⁵-Gly⁴⁶-Gly⁴⁷-Phe⁴⁸. Thesegment displays a unique folding of the polypeptide chain—consistingof a reverse turn, Asn⁴⁴-Tyr⁴⁵-Glu⁴⁶-Gly⁴⁷, stabilized by ahydrogen-bond network involving the side chain of Asn⁴⁴, themain-chain atoms of Asn⁴⁴, Gly⁴⁷ and Phe⁴⁸ and one water molecule.The segment is connected to the C terminus of a ß-strandand expands into a loop region between Asn⁴³ and Ser⁵⁴. Lowvalues for the crystallographic thermal parameters of the segmentindicate that the structure has a rigidity comparable to thatof a ß-pleated sheet. Replacement of Asn⁴⁴ with alanineleads to a far lower enzymatic activity and demonstrates thatthe side chain of Asn⁴⁴ plays a key role in polypeptide foldingin addition to a role in maintaining the segment structure.Substitution of Asn⁴³ by alanine to remove a weak hydrogen bondto the guanine base destabilized the transition state of thecomplex by 6.3 kJ/mol at 37°C. In contrast, mutation ofGlu⁴⁶ to alanine to remove a strong hydrogen bond to the guaninebase caused a destabilization of the complex by 14.0 kJ/mol.A double-mutant enzyme with substitutions of Asn⁴³ by a histidineand Asn⁴⁴ by an aspartic acid, to reproduce the natural substitutionsfound in ribonuclease M_s, showed an activity and base specificitysimilar to that of the wild-type ribonuclease M_s. The segmenttherefore appears to be well conserved in several fungal ribonucleases.     

A vertical multiple-effect diffusion-type solar still coupled with a heat-pipe solar collector

We proposed a newly designed, compact multiple-effect diffusion-type solar still consisting of a heat-pipe solar collector and a number of vertical parallel partitions in contact with saline-soaked wicks. The solar collector and the vertical multiple-effect diffusion-type solar still can be folded or separated when it is carried, so that the still would be easy to carry and shipping cost would be very cheap. The solar energy absorbed on the solar collector is transported as latent heat of working fluid to the vertical multiple-effect diffusion-type still where the energy is recycled to increase the productivity of distillate. The performance of the proposed still is analyzed theoretically, and the still is predicted to produce 21.8 kg/m²d distilled water on a sunny autumn equinox day of 22.4 MJ/m²d solar radiation, and the productivity is greater than that of a vertical multiple-effect diffusion-type still coupled with bulky basin type still.     

Filtration coefficients and physical properties of fluids for osmotic action

In the present study, the filtration coefficient of an acetyl cellulose tubular‐type osmotic membrane is measured with two methods using reverse osmosis and osmosis processes. In addition, the effects of temperature and concentration on the physical properties of fluids needed for studies on osmosis are examined using sodium chloride, potassium chloride, sucrose, and polyethylene glycol 600 aqueous solutions as test fluids. As a result, a new method for measuring the filtration coefficient for osmosis is proposed. Moreover, the present study reveals that little difference exists between the filtration coefficients for these processes. In addition, relations for estimating mass diffusivities, osmotic coefficients, viscosities, and densities of fluids are presented. © 1999 Scripta Technica, Heat Trans Asian Res, 29(1): 72–90, 2000     

Electro-optic multimode interference device using organic materials

We present experimental results verifying the optical robustness of a 1 x 1 multimode interference (MMI) device that is directly butt coupled with optical fibers at 70 degrees C for 1050 h and discuss the gradual increase of polarization dependent loss. Based on this structure, an electro-optic (EO) MMI waveguide device that can control the output optical power by using an electrode structure located directly on top of the multimode is presented. As a proof of principle, we demonstrate the switching operation of the EO-MMI device using commercially available chromophore as the active EO material.     

Design Study of Top Lid with Clamp Structure in JT-60SA Cryostat

JT-60SA is a fully superconducting coil tokamak upgraded from the JT-60U. This paper focused on the integrity of the top lid of cryostat in JT-60SA. The design requirement for the cryostat in normal operations is to achieve vacuum insulation of 10 3 Pa, and the top flange of the top lid is lightly welded onto its body flange. The weld is tensile-loaded by bending deformation of the top lid due to vacuum pressure of external 0.1 MPa. This weld integrity is evaluated with tensile-load reduction, which results in clamp reinforcement. The structural integrity of the top lid is validated.