Influence of alkylpyridine additives in electrolyte solution on the performance of dye-sensitized solar cell

The influence of alkylpyridines additive to an I⁻/I₃⁻ redox electrolyte in acetonitrile on the performance of a bis(tetrabutylammonium)cis-bis(thiocyanato)bis(2,2′-bipyridine-4-carboxylic acid, 4′-carboxylate)ruthenium(II) dye-sensitized TiO₂ solar cell was studied. I–V measurements were performed using more than 30 different alkylpyridines. The alkylpyridine additives showed a significant influence on the performance of the cell. All the additives decreased the short-circuit photocurrent (J_sc), but most of the alkylpyridines increased the open-circuit photovoltage (V_oc) and fill factor (ff) of the solar cell. The results of the molecular orbital calculations suggest that the dipole moment of the alkylpyridine molecules correlate with the J_sc of the cell. These results also suggest that both the size and ionization energy of pyridines correlate with the V_oc of the cell. Under AM 1.5 (100 mW/cm²), the highest solar energy conversion efficiency (η) of 7.6% was achieved by using 2-propylpyridine as an additive, which was more effective than the previously reported additive, 4-t-butylpyridine.     

Phase transition of thermosensitive amphiphilic cellulose esters bearing olig(oxyethylene)s

Summary A series of cellulose esters bearing olig(oxyethylene)s with different degree of substitution (DS) and different length of the oxyethylene chain were synthesized by a homogeneous reaction of cellulose with corresponding monofunctional acid chloride in a 10% LiCl-dimethyl acetoamide (DMAc) solution. The effect of total DS value on the solubility of the derivatives in aqueous solution was investigated. It was found that the lower limit DS value for both water-soluble and amphiphilic derivatives decreases with increasing length of oxyethylene chains. The amphiphilic derivatives, which are soluble in both water and chloroform, precipitate out of aqueous solution on heating without gel forming, such a phase transition behavior was studied in terms of DS value, length of oxyethylene and concentration. The precipitation temperature (T_p) of the amphiphilic derivatives is range from 54°C to 96°C. It decreases with increasing the total DS value, and increases with an increase in the length of oxyethylene chains. The T_p value of the derivatives was found to be almost independent in the concentration range of 1–15 wt %, however the T_p value increases sharply with decreasing polymer concentration when the concentration is lower than 1 wt%. Received: 29 August 2000/Revised version: 16 October 2000/Accepted: 31 October 2000     

Structural Investigation of 95(0.6Li2S0.4SiS2)5Li4SiO4 Oxysulfide Glass by Using X-ray Photoelectron Spectroscopy

S2 p and O1 s photoelectron spectra were obtained for the 95(0.6Li₂S0.4SiS₂)5Li₄SiO₄ oxysulfide glass prepared by twin-roller quenching. A four-peak deconvolution technique was used to separate the S2 p peak of the glass into the components of bridging and nonbridging sulfur atoms. As a result of the deconvolution of the S2 p peak, we found that ∼92% of the sulfur atoms were present as nonbridging atoms. The O1 s peak of the glass was separated into two components: bridging and nonbridging oxygen atoms. This separation of the O1 s peak indicated that ∼85% of the oxygen atoms were present as bridging oxygen atoms.     

Effects of gomisin A on the promotor action and serum bile acid concentration in hepatocarcinogenesis induced by 3'-methyl-4-dimethylamino-azobenzene

The effects of gomisin A, a lignan component of Schizandra fruits, on the promotion stage of hepatocarcinogenesis initiated by 3'-methyl-4-dimethylamino-azobenzene (3'-MeDAB) in male Donryu rats were investigated. When different types of tumor promotors, phenobarbital (PB) and deoxycholic acid (DCA), were administered for 5 weeks after initiation by 3'-MeDAB, preneoplastic alterations in the liver, determined by glutathione S-transferase placental form (GST-P), were markedly increased. Gomisin A significantly inhibited the increase in number and size of GST-P positive foci, regardless of the promotor. This lignan inhibited the increase in serum bile acid concentration by administration of DCA, but hardly influenced the serum bile acids in the PB-combined group. These results suggest that the inhibitory effect of gomisin A on the promotive action of DCA is based on improving bile acid metabolism, but regarding the action of PB, the effect could not be elucidated from the metabolism of bile acids.     

Vacuum seal for a rectangular flange

A new vacuum seal for a rectangular flange used in r.f. equipments, was developed. The vacuum seal consists of a recess with a flat surface, machined into a rectangular flange, a rectangular metal gasket with a raised projection on one face, and a mating flange with a recess and raised projection. No leak greater than 1 × 10⁻¹⁰ Pa m³/s was found in leak tests, before and after baking cycles (100 °C, 12 h).     

An energy trading system with consideration of CO2 emissions

Abatement of CO₂ emission is one of the most important issues in the 21st century regarding preservation of the earth environment. This paper addresses a utility operations planning problem for distributed energy management systems (DEMSs), where we are to obtain optimal plans that minimize both costs and CO₂ emissions. A DEMS consists of multiple entities that seek their own economic profits. In this paper, we give a mathematical formulation of the utility operations planning problem for each entity, and propose an energy trading market, which utlizes a multi‐attribute auction protocol in order to deal with both a price and a CO₂ emission rate. Experimental results show that collaboration among entities through the market provides a more profitable plan for each entity and abatement of CO₂ emission is also achieved. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(4): 54–63, 2008; Published online in Wiley InterScience ( www.interscience.wiley. com ). DOI 10.1002/eej.20418     

High-efficiency hot-electron transport in GaInAs/InP hot electron transistor grown by OMVPE

Improved characteristics of the GaInAs/InP hot electron transistor (HET) fabricated by organo-metallic vapour phase epitaxy (OMVPE) are reported. The common-emitter current gain was 8 for the base thickness of 40 nm at 77 K. This result shows a promising potential for the heterostructure material system of GaInAs/InP for high-speed ballistic electron devices.<>     

GaInAs-GaInNAs-GaInAs intermediate layer structure for longwavelength lasers

Proposes two new structures, the GaInAs-GaInNAs intermediate layer (IML) and the GaInN_xAs graded wells, which show better optical properties than the commonly used GaInNAs-GaAs rectangular quantum-wells. A 1240-nm emitting IML laser has been achieved with a low-threshold current density (200 A/cm²/well) and a relatively high characteristic temperature (T_o=100 K). The IML structure is very promising for long wavelength GaAs-based laser applications     

In vitro selection of aptamers that bind to ribosome-inactivating toxins

Ribosome-inactivating proteins, such as ricin, pepocin and gypsophilin, catalyze the hydrolysis of a single N-glycosidic bond at a specific position in rRNAs. Aptamers targeting pepocin were selected from a random sequence RNA pool that spanned 30 positions. After 8 rounds, the anti-pepocin aptamers were sequenced and a conserved hairpin motif was identified. Interestingly, the selected motif is quite different from the toxin-binding domains of rRNAs.