Silicide formation by solid-state diffusion in MO/Si multilayer thin films

The solid-state reaction of Mo/Si multilayer thin films produced by the r.f. magnetron sputtering technique was examined using differential scanning calorimetry (DSC) and X-ray diffraction and was explained by the concepts of effective driving force and effective heat of formation. In constant scanning-rate DSC, there were two exothermic peaks representing the formation of h-MoSi₂ and t-MoSi₂, respectively. The activation energy for the formation of h-MoSi₂ was 1.5 eV, and that of t-MoSi₂ was 7.8 eV. Nucleation was the rate-controlling mechanism for each silicide formation. The amorphous phase was not formed in the Mo/Si system as predicted by the concept of effective driving force. h-MoSi₂, the first crystalline phase, was considered to have lower interfacial free energy than t-MoSi₂, and by increasing the temperature, it was transformed into more stable t-MoSi₂.     

Species differences in pharmacokinetics of a hepatoprotective agent, YH439, and its metabolites, M4, M5, and M7, after intravenous and oral administration to rats, rabbits, and dogs

Pharmacokinetic parameters of YH439 and its metabolites, M4, M5, and M7, were compared after iv administration of YH439 to rats (1-10 mg/kg), rabbits (1-10 mg/kg), and dogs (1-20 mg/kg) and oral administration of YH439 to rats (50-500 mg/kg) and dogs (0.5-2 g per whole body weight). After oral administration of YH439 to rats, the F values were 3.67, 1.33, and 0.859% for YH439 oral doses of 100, 300, and 500 mg/kg, respectively. However, the F value increased significantly, 21.2%, after oral administration of YH439-contained mixed micelles (10 mg as free YH439) to rats due to increased water solubility of YH439. Species differences in the pharmacokinetics of YH439 and its metabolites were found. First, M7 was detected in both plasma and urine after both iv and oral administration of YH439 to dogs, whereas it was detected neither in rats nor in rabbits, indicating that considerable amount of M7 was formed from YH439 only in dogs. Second, the AUC (or AUC0-->t) ratios of M4 to YH439 after iv administration of YH439 were 24.6-31.3, 42.2-49.2, and 2200-7640% for rats, rabbits, and dogs, respectively, indicating that formation of M4 after iv administration of YH439 was maximal in dogs. Third, the AUC (or AUC0-->t) ratios of M5 to YH439 after iv administration of YH439 were 103-127, 2.93-3.31, and 92.4-158% for rats, rabbits, and dogs, respectively, indicating that formation of M5 after iv administration of YH439 was minimal in rabbits.     

Preparation of sulfonated novel poly(bis[4‐(3‐aminophenoxy) phenyl]sulfone pyromellite)imide derivatives by heterogeneous sulfonation

Sulfonated poly(bis[4‐(3‐aminophenoxy)phenyl]sulfone pyromellite)imide derivatives with various ion‐exchange capacities were prepared by heterogeneous sulfonation with chlorosulfonic acid. The effects of sulfonating agent concentration, reaction temperature, and reaction time were investigated. The mechanical and thermal properties, contact angle, change of polydispersity, and solubility were calculated for studying change of their properties. The reactions were effective, when the temperature is <10 °C and the concentration of chlorosulfonic acid is between 0.05 and 0.1 M. The value of ion‐exchange capacity was increased with reaction time, reaction temperature, and concentration of sulfonating reagent. Thermal and mechanical properties were nearly unchanged according to the degree of sulfonation, but the hydrophilicity indirectly measuring contact angle was increased with increasing the value of ion‐exchange capacity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1881–1887, 2002     

The chemistry of Pd in cellulose acetate

Pd(OAc)₂ complex has been incorporated in cellulose acetate (CA) as a dispersion medium using cosolvent (THF). The interactions Pd(II) complexes and cellulose acetate are examined by infrared spectroscopy and thermal analysis (DSC). The chemical reactivities of Pd–CA films have been investigated by reacting Pd sites with CO, H₂, O₂, and C₂H₄ in the temperature range 25–150°C and at the pressure of less than 1 atm. Two different Pd-carbonyls and a Pd(O)-hydride species formed in CA are characterized by their infrared spectra. Treatment of 10 wt % Pd–CA films with hydrogen (600 torr) at 70°C produces small Pd metal particles of ca. 30–60 Å in diameter in CA, which show catalytic activities under mild conditions in the reactions such as hydrogenation of C₂H₄ and oxidation of CO.     

Coating of MgO nanorods with protective layers: Sputtering with a Si target, structure, and photoluminescence properties

We have synthesized MgO/SiO_x core-shell nanorods by employing a sputtering technique with a Si target, for sheathing the MgO nanorods. The samples were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope and photoluminescence (PL) spectroscopy. The SiO_x shell was close to amorphous, whereas the MgO core was crystalline with a cubic structure. The shape and peak positions of the PL spectrum were not changed by the coating.     

Proposal of novel gain-levered MQW DFB laser with high andred-shifted FM response

A gain-levered multiple quantum well (MQW) distributed feedback (DFB) laser with high FM efficiency is discussed. The device consists of three sections with different bandgap energy. It can be fabricated by a selective area metalorganic vapor phase epitaxy (MOVPE) growth technique. Numerical analysis shows that a flat, red-shifted, and high FM efficiency of above 1 GHz/mA at 20-mW output power can be realized using the gain levering scheme     

Percutaneous mitral balloon valvuloplasty in patients with restenosis after surgical commissurotomy: a comparative study

The inhibition of acetylcholinesterase secretion by male and female Heligmosomoides polygyrus was tested on worms taken from experimentally infected mice and maintained for 3 days in vitro in levamisole. The dose inhibiting 50% of enzyme secretion (ID 50) of male worms was twice the ID 50 for female worms. A similar difference was observed in vivo between the dose of levamisole removing 50% (LD50) of male and female worms from the mouse. Acetylcholinesterase secretion by worms and ID 50 were tested in vitro at 3-weekly intervals from 3 to 21 weeks post infection (WPI). Acetylcholinesterase secretion was always significantly higher for male than for female worms. A decrease of ID 50, correlated with the age of the worms was observed: from 1.5 to 0.5 micrograms/ml for males and from 0.7 to 0.1 micrograms/ml for females. These results were confirmed in vivo by a higher efficacy of the anthelminthic at 21 than at 4 WPI.     

Comparative study of flame structures and NOx emission characteristics in fuel injection recirculation and fuel gas recirculation combustion system

A numerical study with momentum‐balanced boundary conditions has been conducted to grasp the chemical effects of added CO₂ to fuel‐ and oxidizer‐sides on flame structure and NO emission behaviour in H₂–O₂ diffusion flames with varying flame location. A reaction mechanism is proposed to show better agreements with experimental results in CO₂‐added hydrogen flames. Oxidizer‐side dilution results in significantly higher flame temperatures and NO emission. Flame location is dramatically changed due to high diffusivity of hydrogen according to variation of the composition of fuel‐ and oxidizer‐sides. This affects flame structure and NO emission considerably especially the chemical effects of added CO₂. The present work also displays separately thermal contribution and prompt NO emission due to the chemical effects caused by thermal dissociation of added CO₂ in NO emission behaviour. It is found that flame temperature and the flame location affect the contribution of thermal and prompt NO due to chemical effects considerably in NO emission behaviour. Copyright © 2004 John Wiley & Sons, Ltd.     

Bit-error-rate analysis of optically preamplified receivers usingan eigenfunction expansion method in optical frequency domain

An accurate method of analysis is presented for optically preamplified receivers using an eigenfunction expansion technique in the optical frequency domain. Excluding three conventional simplifying assumptions on optical filters, electrical circuits, and amplified spontaneous emission, our method can give accurate predictions to the bit-error probabilities in real systems where the amplified spontaneous emission is the dominant noise