Single-molecule conductance of π-conjugated rotaxane: new method for measuring stipulated electric conductance of π-conjugated molecular wire using STM break junction

An electronic conductance with small fluctuations, which is stipulated in single-molecule junctions, is necessary for the precise control of single-molecule devices. However, the suppression of conductance fluctuations in conventional molecular junctions is intrinsically difficult because the fluctuations are related to the contact fluctuations and molecular motion. In the present study involving experimental and theoretical investigations, it is found that covering a single π-conjugated wire with an α-cyclodextrin molecule is a promising technique for suppressing conductance fluctuations. The conductance histogram of the covered molecular junction measured with the scanning tunneling microscope break-junction technique shows that the conductance peak for the covered junction is sharper than that of the uncovered junction. The covering technique thus has two prominent effects: the suppression of intramolecular motion, and the elimination of intermolecular interactions. Theoretical calculations of electronic conductance clearly support these experimental observations.     

Fluorogenic derivatization reagents suitable for isolation and identification of cysteine-containing proteins utilizing high-performance liquid chromatography-tandem mass spectrometry

The fluorogenic derivatization reagents with a positive charge, 4-(dimethylaminoethylaminosulfonyl)-7-chloro-2,1,3-benzoxadiazole (DAABD-Cl) and 7-chloro-2,1,3-benzoxadiazole-4-sulfonylaminoethyltrimethylammonium chloride (TAABD-Cl), are proposed for use in proteomics studies. Following derivatization of protein mixtures with these reagents, a series of standard processes of isolation, digestion, and identification of the proteins were performed utilizing high-performance liquid chromatography-fluorescence detection and tandem mass spectrometry with the probability-based protein identification algorithm. Both DAABD and TAABD derivatives were detected fluorometrically at the femtomole level and showed more than 100-fold improvement in sensitivity compared to the underivatized original compounds with an electrospray ionization ion trap mass spectrometer analysis. The modification of the MASCOT database search system memorized with the fragment information of a DAABD-attached Cys residue allowed the identification of the proteolytic peptide fragments of the derivatized bovine serum albumin (BSA) with an estimated 38% sequence coverage of BSA. Utilizing DAABD-Cl as a derivatization reagent, identification of several proteins was also possible in a soluble extract of Caenorhabditis elegans (10 microg of protein). Consequently, for identification of proteins in the complex matrixes of proteins, DAABD-Cl could be a more appropriate reagent than ammonium 7-fluoro-2,1,3-benzoxadiazole-4-sulfonate as reported previously.     

1.3?m InGaAsP/InP distributed-feedback P-substrate partially inverted buried-heterostructure laser diode

A novel 1.3?m InGaAsP/lnP distributed-feedback buried-heterostructure laser diode on p-type InP substrate has been developed utilising a dopant diffusion technique. The laser has achieved a threshold current as low as 20 mA and high output power of 32 mW under CW and SLM operation.     

Synthesis and antidiuretic activities of novel glycoconjugates of arginine-vasopressin

Arginine-vasopressin (AVP) was acylated with various acyl azides (2a-j) in pH 9.1 buffer to give AVP derivatives (11a-j) modified at the tyrosine side chain with a carbohydrate via a spacer arm. Glycoconjugates of AVP modified at the N-terminal amide (12a-e) were also synthesized from AVP and carboxylic acids (3a-e) using dicyclohexylcarbodiimide and 1-hydroxybenzotriazole as coupling agent. Analogues (11a-j) exhibited greater in vivo antidiuretic activity than AVP. AVP and glycoconjugates (12a-e) were stable in rat plasma. On the other hand, glycoconjugates (11a-i) were found to readily convert to AVP according to first order kinetics. Hence, 11a-j are considered to be prodrugs of AVP.     

Tissue-targeting ability of saccharide-poly(L-lysine) conjugates

To evaluate the effect of introducing a saccharide moiety to poly(amino acids) on tissue distribution, several glycoconjugates of epsilon-(2-methoxyethoxyacetyl)-poly(L-lysine) of three molecular weights were synthesized using an octylene spacer between the sugar and polymer chain. Methoxyethoxyacetylation of the epsilon-amino group of the lysine unit in poly(L-lysine) was useful for avoiding nonspecific distribution to many tissues as the result of cationic charges. The tissue-targeting ability of each saccharide moiety was considered as the actual amount changed in each tissue caused by saccharide modification. Galactose terminated saccharides such as galactose, lactose and N-acetylgalactosamine accumulated exclusively in the liver, probably by the hepatic receptor. These conjugates could therefore be good carriers for a drug delivery system to the liver. On the other hand, the mannosyl and fucosyl conjugates were preferentially delivered to the reticuloendothelial systems such as those in the liver, spleen and bone marrow. In particular, fucosyl conjugates accumulated more in the bone marrow than in the spleen. Xylosyl conjugates accumulated mostly in the liver and lung. Generally, the accumulated amount in the target tissue increased with increasing molecular weight and an increased number of saccharides on one molecule of polymer.     

Sulfide capacity of CaO-CaF2-SiO2 slags

The sulfide capacityC _S ^2- = (pct S^2-) · (P _{O 2}/P _{S 2})^1/2) of CaO-CaF₂-SiO₂ slags saturated with CaO, 3CaO · SiO₂ or 2CaOSiO₂ was determined at 1200 °C, 1250 °C, 1300 °C, and 1350 °C by equilibrating molten slag, molten silver, and CO-CO₂ gas mixtures. Higher sulfide capacities were obtained for CaO-saturated slags. A drastic decrease was observed in those values when the ratio pct CaO/pct SiO₂ is less than 2. The sulfur partition between carbon-saturated iron melts and presently investigated slags was calculated by using the sulfide capacities obtained and the activity coefficient of sulfur in carbon-saturated iron, which was also experimentally determined. For slags saturated with CaO, partitions of sulfur as high as 10,000 were obtained at 1300 °C and 1350 °C. Correlations between the sulfide capacity and other basicity indexes such as carbonate capacity and theoretical optical basicity were also discussed. Formerly with the Department of Metallurgy, The University of Tokyo.     

Development of Lignin-Based Terpolyester Film and Its Application to Separator Material for Electric Double-Layer Capacitor

For new application of technical lignins as separator material for electric double-layer capacitor (EDLC), we tried first to prepare bipolyester film by melt-polycondensation of polyethylene glycol lignin (PEGL) and maleic anhydride. The EDLC assembled with this film, however, showed lower electrochemical performance than the reference EDLC with commercial cellulosic separator. Porous bipolyester film was then prepared and the resulting EDLC exhibited improved specific capacitance, but high intrinsic and charge transfer resistances. Non-porous terpolyester film was prepared next, using polyethylene glycol 500,000 to improve flexibility of the film, which might lower the resistances. This film was flexible enough and provided the resulting EDLC with superior electrochemical performance to the bipolyester film. EDLC with porous terpolyester film was finally prepared and showed the highest electrochemical performance, comparable to the reference EDLC. Porous morphology and flexibility were key factors to fabricate lignin-based self-standing film as separator material for high-performance EDLC.     

Electrically Conductive CNT-Dispersed Silicon Nitride Ceramics

Carbon nanotube (CNT)-dispersed Si₃N₄ ceramics with electrical conductivity were developed based on the lower temperature densification technique, in which the key point is the addition of both TiO₂ and AlN as well as Y₂O₃ and Al₂O₃ as sintering aids. This new ceramic with a small amount of CNTs exhibits very high electrical conductivity in addition to high strength and toughness. Since Si₃N₄ ceramics with Y₂O₃–Al₂O₃–TiO₂–AlN were originally used as a wear material, electrically conductive Si₃N₄ ceramics are expected to be applied for high-performance static-electricity-free bearings for aerospace and other high-performance components.     

Renal drug targeting using a vector "alkylglycoside"

Cirrhosis and portal hypertension may be associated with pulmonary hypertension and pulmonary dysfunction. However, morphological pulmonary vascular lesions in patients with cirrhosis have not been well characterized morphometrically. We morphometrically evaluated pulmonary vessels in liver transplant recipients with pretransplantation cirrhosis and correlated our findings with pretransplantation cardiopulmonary function, postoperative course, and postmortem cardiopulmonary findings. Autopsy lung slides from 23 transplant recipients with pretransplantation cirrhosis were examined. External vessel diameter, intimal thickness, and arterial medial thickness were measured with a micrometer after pentachrome staining. The percent of total diameter comprised by intima or media was calculated for each vessel. Medical records were reviewed for smoking history, pretransplantation cardiopulmonary function testing, and postoperative course. Autopsy cases without liver or significant cardiopulmonary diseases, matched for age, sex, and smoking history, served as controls. Transplant recipients had significantly more pulmonary venous intimal thickening than matched controls (P <.0001). Sixty-five percent (15 of 23) of these patients had some degree of pretransplantation pulmonary dysfunction, defined by abnormalities in pulmonary function tests, oxygen saturation, and/or increased pulmonary artery pressures. However, the severity of venous intimal thickening did not correlate with the severity of pretransplantation pulmonary dysfunction. Arterial intimal and medial thickness were not statistically significantly different from controls. Pulmonary venous intimal thickening and resultant luminal impingement are morphological findings not previously described in this population. The arterial lesion, when present, is similar to that seen in pulmonary hypertension from other causes. These pulmonary vascular lesions may be implicated in pulmonary dysfunction in patients with cirrhosis and may be associated with increased posttransplantation cardiopulmonary morbidity and mortality.