Influence of electrolytes on the photovoltaic performance of organic dye-sensitized nanocrystalline TiO2 solar cells

We have studied the influence of electrolytes on the photovoltaic performance of mercurochrome-sensitized nanocrystalline TiO₂ solar cells using LiI, LiBr, and tetraalkylammonium iodides as the electrolyte. Short-circuit photocurrent density (J_sc) and open-circuit photovoltage (V_oc) depended strongly on the electrolyte. J_sc of 3.42 mA cm⁻² and V_oc of 0.52 V were obtained for the LiI electrolyte and J_sc of 2.10 mA cm⁻² and V_oc of 0.86 V were obtained for the Pr₄NI electrolyte. This difference in photovoltaic performance was due to the change in the conduction band level of the TiO₂ electrode. Large V_oc of 0.99 V was obtained for the LiBr electrolyte due to the large energy gap between the conduction band level of TiO₂ and the Br/Br₂ redox potential. Solar cell performance also depended strongly on organic solvent, suggesting that the physical properties of solvents such as Li ion conductivity and donor number affect photovoltaic performance.     

Sinterability of various high-purity magnesium oxide powders

The sinterability of high-purity MgO powders with different production histories was investigated to make clear the relationship between the powder characterization, the densification processes, and the changes in microstructure both with increasing temperature at a rate of 10° C min^–1 and at a fixed temperature of 1450° C for 5 h. The densification behaviour and the changes in microstructure of these compressed bodies were affected chiefly by their original surface activity and degree of agglomeration, depending on the production histories: (i) the ultra-fine and well-dispersed powder prepared by the vapour-phase oxidation process showed that densification proceeded with an appreciable grain growth with few closed pores remaining; (ii) powder derived from the sea-water magnesia process showed that the densification behaviour was affected by the species of magnesium salt, i.e. basic magnesium carbonate or magnesium hydroxide, used as a precursor; however, whichever magnesium salt was used, its sintered compact showed similar closed porosities and grain-size distributions; (iii) powder derived from the spark-discharge process contained skeletons of the original Mg(OH)₂ particles; however, the densification proceeded gradually with slow grain growth, reflecting the fact that the powder has a moderate surface area (36 m² g^–1). The sintered compact from (iii) had a small closed porosity and the smallest grain-size distribution among the compacts used in this investigation.     

Effect of mechanical properties of material on rate of fatigue crack propagation

Many experimental and analytical equations on a rate of a fatigue crack propagation have been proposed. However, it seems that they can not fully express its complex behavior. There are still many problems remaining to be solved in order to clarify its mechanism. One of them is to clarify the relation between the rate of the crack propagation and the mechanical properties of material. In this paper, the rate of the crack propagation is analysed to clarify this problem. This analysis is based on the observation results of the fatigue crack propagation behavior previously by the authors. The analytical result is compared with the experimental one to make sure that they agree with each other. The conclusion obtained is; the rate of fatigue crack propagation is expressed by using the stress intensity factors as

$\text{dl}\text{dN}\text{= {}\text{c}\text{[Y}{}^2\text{F}{}^{\mathrm{a}}\text{E}{}^{\mathrm{a(1?n)}}\text{]}\text{} (K}{}_{\max }\text{)}{}^2\text{(K}{}_{\mathrm{a}}\text{)}{}^{\mathrm{a(2?n)}}$

. where C is a constant; E, Young's modulus; F, plastic coefficient; Y, yield stress; K_max and K_a, maximum and amplitude of the stress intensity factor, and α and n, exponents of the Manson-Coffin's law and work-hardening.     

Stress intensity factors of an inclined elliptical crack near a bimaterial interface

In this paper the stress intensity factors are discussed for an inclined elliptical crack near a bimaterial interface. The solution utilizes the body force method and requires Green’s functions for perfectly bonded semi-infinite bodies. The formulation leads to a system of hypersingular integral equation whose unknowns are three modes of crack opening displacements. In the numerical calculation, unknown body force densities are approximated by using fundamental density functions and polynomials. The results show that the present method yields smooth variations of stress intensity factors along the crack front accurately. Distributions of stress intensity factors are presented in tables and figures with varying the shape of crack, distance from the interface, and elastic modulus ratio. It is found that the inclined crack can be evaluated by the models of vertical and parallel cracks within the error of 24% even for the cracks very close to the interface.     

Electron microscopic observation on the parathyroid gland of the cardiomyopathic hamster (UM-X7.1 Syrian hamster).

The ultrastructure of the parathyroid gland (PTG) of the UM-X7.1 cardiomyopathic hamster (the UM-X7.1) was qualitatively and quantitatively compared with that of the normal hamster. In the UM-X7.1, the Golgi apparatus and rER were well developed compared with those of the control hamster. Morphometric analysis revealed that the mean values of the Golgi apparatus, rER and large vacuolar bodies were significantly greater in the UM-X7.1 than in the normal hamster and the mean value of lipid droplets was significantly less in the UM-X7.1 than in the normal hamster. Ultrastructurally, we consider that in the UM-X7.1, the synthesis and release of the parathyroid hormone may be activated by an excessive amount of circulating catecholamine, and the functional activity of the PTG may be higher than that in the normal hamster.     

Simple common-collector full-monolithic preamplifier for 560 Mbit/s optical transmission

A simple common-collector full-monolithic preamplifier is developed using an advanced 3 ?m Si-bipolar IC technology SICOS. The amplifier characteristics are a 650 MHz bandwidth and a 5.2 pA/?(Hz) equivalent input noise current at a 3 k? transimpedance. Measured optical sensitivity of a front end consisting of the amplifier and a Ge-APD is ?36.2 dBm for an error rate of 10?9 at a 560 Mbit/s bit rate and 1.3 ?m wavelength.     

A new method for evaluation of motor deficits in 3-acetylpyridine-treated rats

BACKGROUND: approximately one-third of patients with Alzheimer's disease (AD) respond favourably to the anticholinesterase tacrine, but the drug's usefulness is marred by a high incidence of side-effects. OBJECTIVE: to discover if AD patients with white matter low attenuation (WMLA) represents a subgroup that responds differently to tacrine from those with no WMLA. DESIGN: the results come from a combination of double-blind and open studies. Seventy-two AD patients prescribed tacrine in our centre were divided into two groups according to the presence or absence of WMLA on brain CT scans. We compared the rate of response to and withdrawal from tacrine between the groups. Response was defined as an improvement in the Mini-Mental State Examination score of three or more points at 3 months. RESULTS: 18 of the 72 patients were found to have WMLA. There was no significant difference in the proportion of patients responding to tacrine in each group (28.5% in those with WMLA and 31% in those without), but the rate of withdrawal from tacrine did differ: 11 patients with WMLA (61%) had to be withdrawn prematurely, compared with 14 patients (26%) in the group without evidence of WMLA (P = 0.015). CONCLUSION: AD patients with WMLA can still respond to tacrine, although the rate of withdrawal from treatment is much higher in such patients.     

Photoluminescence of nitrogen-doped anatase

Photoluminescence depending on nitrogen concentration was investigated using anatase-type TiO₂ prepared by the calcination of a mixture of titanyl sulfate hydrate and urea. The substitutional ratio (x) of nitrogen in TiO₂ was successfully varied from 0.004 to 0.022 by changing the molar ratio of the mixture. The absorbance at 380–560 nm due to the formation of mid-gap states was proportional to the substitutional ratio of nitrogen controlled by the preparation conditions. In contrast, the fluorescent intensity at 382 nm originating from the band-to-band transition monotonically decreased with an increase in the substitutional ratio with an expansion of the anatase lattice. On the other hand, the maximum intensity of photoluminescence at 560 nm excited at 350 nm, which could be associated with the transition from the conduction band to the mid-gap states, was observed at x = 0.01. The optimal substitutional ratio for the emission was almost agreed with that for the photocatalytic decomposition of methylene blue and acetaldehyde under visible-light illumination. The photoluminescence was fundamentally determined by the balance between photoexcitation originating from a sufficient number of mid-gap states and deactivation of excited electrons and holes due to lattice distortion or defective states induced with the nitrogen doping.     

A new choleretic effect of folinic acid

BACKGROUND/AIMS: In the chemotherapy of recurrent gastric cancer with 5-fluorouracil and folinic acid, an interesting phenomenon, the reduction of jaundice and improvement of liver function, was observed. The aim of this study was to investigate the mechanism of this phenomenon, and to confirm a choleretic effect of folinic acid. METHODOLOGY: The bile duct of anesthetized rats was catheterized, and bile was collected. Bile volume and total bile acid production following intraperitoneal administration of folinic acid were determined and compared to those of control rats. RESULTS: Both bile volume and total bile acid production increased following intraabdominal administration of folinic acid. CONCLUSIONS: Folinic acid has a newly described pharmacologic effect of stimulating bile acid-dependent choleresis. It is possible that folinic acid may become a new drug for the treatment of jaundice or for the improvement of overall liver function.