Reduction of droplet of tantalum oxide using double slit in pulsed laser deposition

We developed a double slit method in order to reduce droplets that were a problem in pulsed laser deposition (PLD) of tantalum oxide. The tantalum oxide films were deposited using KrF excimer laser ablation of a Ta target in 5 mass% O₃ at a pressure of 10 Pa. Stoichiometric and dense films with few droplets were obtained at a pressure of 10 Pa. Without double slit, as the laser pulses increased, the number of droplets containing rich metal on the film gets increased and its size became larger, and the surface morphology of the target also became more and more rugged. It was found that the number of droplet could be controlled by changing the initial roughness of the target. The number of droplets with a diameter size of under 1 μm was decreased to 1/10 of their sizes. Droplets larger than 3 μm, which mostly affect the corrosion resistance and hardly increase even beyond the laser pulses of 100 000. It is evident from this study that the double slit is a very effective method for reducing the droplets, which are otherwise a problem often seen in film production by PLD.     

Grazing exit electron probe microanalysis of submicrometer inclusions in metallic materials

Grazing exit electron probe microanalysis (GE-EPMA) is a new method of EPMA in which characteristic X-rays emitted from only near-surface regions of a specimen are detected at extremely low exit angles near 0 degrees (the grazing exit condition). This technique requires the analytical objects exist on a flat surface. Therefore, the GE-EPMA analysis has been used only for the analysis of particles or a thin film on a flat substrate so that there were only few applications for practical analysis. As a new application, we have carried out GE-EPMA analysis of approximately 0.2-microm inclusions on stainless steel, which appeared to be a projection on the specimen surface with chemical etching. The GE-EPMA quantitative results were in excellent agreement with those of inclusions that were extracted from the stainless steel and analyzed by EPMA with conventional exit condition (30 degrees). This method could be, therefore, applied to the analysis of the submicrometer inclusion in a wide variety of metallic materials if the inclusion appears to be a projection with chemical etching treatment.     

Synthetic potential of molluscan sulfatases for the library synthesis of regioselectively O-sulfonated D-galacto-sugars

The substrate specificities of three molluscan sulfatases (E.C. 3.1.6.1; snail, abalone, and limpet origins) were investigated with assorted p-nitrophenyl (pNP) di-O-sulfonated beta-D-galactopyranosides and beta-lactosides [3,6-SO(3) Gal (1), 3',6'-SO(3) Lac (2), 4, 6SO(3) Gal (3), 2,6-SO(3) Gal (4), 3,4-SO(3) Gal (5), and 3,6-SO(3) GalNAc (6); Ac, acetyl; Gal, galactose; Lac, lactose] together with mono-O-sulfonated beta-D-galactopyranoside [pNP 3SO(3)-Gal (7)] and tri-O-sulfonated alpha-D-galactopyranoside [2,3,6-SO(3)-alpha-Gal (11)]. Some notable differences between the substrate specificity of the three sulfatases were disclosed; snail sulfatase hydrolyzed the 3O- and 2O-sulfo groups of 1 and 4, respectively, to afford 6SO(3) Gal (9) in high yields, while the abalone enzyme did not act on 4. Only the limpet enzyme could cleave the 3O-sulfo groups of 7 to give pNP beta-galactoside. In contrast, every enzyme could utilize 11 as a good substrate to afford a mixture of 6SO(3)-alpha-Gal (13) and 2,6-SO(3) alpha-Gal (12). None of the enzymes could cleave the O-sulfo groups of 5 and 6, which indicates that a primary 6O-sulfo group tends to promote the enzymatic hydrolysis of O-sulfo groups at the secondary positions.     

Establishment of a simple method for measurement of chronic blood flow in uterine artery of pregnant cows

Blood flow to the gravid uterine horn of seven multiparous Holstein cows (mean +/- SD, BW = 625.5 +/- 82.4 kg; age = 4.7 +/- 1.7 yr; parity = 2.9 +/- 1.1 yr) was measured from d 225 of gestation to parturition using transit-time ultrasonic blood flow probes placed around the middle uterine artery. Surgery was conducted on d 215 of gestation. The cows were sedated with xylazine and local anesthesia (procaine or bupivacain hydrochloride) during surgery. The surgical operations were conducted at the flank of standing cows. A transit time ultrasonic flow probe ("S" series, diameter 12 or 14 mm, Transonic Systems Inc., Ithaca, NY) was fitted surgically around the uterine artery of each cow. Surgery was completed within 2 h of anesthesia, and the animals recovered rapidly following surgery. Uterine blood flow (UBF, L/min) was recorded at 10-s intervals for 1395 min; these values were averaged to determine UBF. Cows exhibited normal gestation lengths (279.1 +/- 7.4 d), gave birth to normal healthy calves (birth weight = 40.6 +/- 6.6 kg), and had no retained placentas. The UBF increased significantly (P < 0.01) from d 225 (6.67 +/- 2.47) to d 249 (8.23 +/- 2.89) of gestation, but the latter UBF was similar to that of d 266 (8.38 +/- 2.70). The increased UBF after d 225 indicates increased demand of nutrients of fetus with the progress of gestation. The range of mean UBF varied widely among individual cows from 4.1 L/min to 12.2 L/min. Our method is useful for chronic measurement of UBF in cows for nutritional or physiological studies and does not require sophisticated facilities or special surgical technique.     

Superfluid-Normal Interface of 4He Near a Wall

We observed a profile of nonequilibrium superfluid-normal (SN) interface of ⁴He near a vertical wall. A glass, brass or copper wall was used. The SN interface was produced by cooling liquid ⁴He in a bath from the bottom, where liquid ⁴He was pumped through a flow impedance in order to cool down the liquid. Superfluid (Normal fluid) occupied the lower (upper) part of the bath. The SN interface was visualized by three methods: simple visualization, shadowgraphy and schlieren method. The interface touched a vertical glass wall at almost 90°. A large hollow was observed near a brass wall which had intermediate thermal conductivity. Downward flow was observed on a copper wall due to the very good thermal conductivity of the wall. Various types of interface profile were observed depending on the thermal conductivity of the wall used.      

DNA promotes the activation of oxygen molecules by binuclear cobalt(II) compounds

We have observed that binuclear cobalt(II) compounds with H(HPTP), Co₂(HPTP)(CH₃COO)(ClO₄)₂ and Co₂(HPTP)Cl(ClO₄)₂, react with oxygen molecules when DNA is present in the solution, cleaving the DNA (H(HPTP) denotes N,N,N′,N′-tetrakis(2-pyridylmethyl)-1,3-diaminopropane-2- ol).     

Angular distribution of REC for Ar on C at 1 MeV/amu

The angular distribution of K-REC for 45.7 and 51.9 MeV Ar⁴⁺ + C has been measured and found to be consistent with sin²θ_lab.     

Synthesis and characterization of 1,3,2-diazaboroine derivatives for organic thin-film transistor applications

2,2′-(1,4-Phenylene)bis(2,3-dihydro-1H-naphtho[1,8-de]-1,3,2-diazaboroine) [PND] and 2,2′-(4,4′-biphenylene)bis(2,3-dihydro-1H-naphtho[1,8-de]-1,3,2-diazaboroine) [BND] were synthesized and characterized by using differential scanning calorimetry (DSC) measurements, single crystal X-ray structure analysis, UV–vis absorption and electrochemical measurements, thin-film X-ray diffraction (XRD) and AFM studies. Organic field-effect transistors (OFETs) were fabricated by vacuum deposition with a bottom contact geometry using Au electrodes. Annealing treatment optimizes the organic active layer and increases the charge carrier mobility. Field-effect mobilities of 7.2 × 10^?3 for PND and 4.1 × 10^?4 cm² V^?1 s^?1 for BND were found.     

Phonon emission from a discrete sine-Gordon breather

Phonon emission from a large-amplitude discrete sine-Gordon breather was studied numerically for a small degree of discreteness. In contrast to the case of highly discrete system investigated by Boesch and Peyrard (Phys. Rev. B 43 (1991) 8491), it was found that the resonance between the breather's oscillation and the phonons of the lower phonon band edge (κ=0) takes place for a small degree of discreteness.