Crystal Growth and Electrical Properties of Pb((Zn1/3Nb2/3)0.91Ti0.09)O3 Single Crystals Produced by Solution Bridgman Method

Piezoelectric Pb((Zn_1/3Nb_2/3)_0.91Ti_0.09)O₃ (PZNT 91/9) single crystals 40 mm in diameter were successfully grown from solution by the Bridgman method with a PbO flux. The crystals were grown in a platinum crucible heated to 1130°C. Growth rate was 0.35 mm/h. The obtained crystals were ~40 mm in diameter 20 mm in length and were a rust-brown color. The Curie temperature, T _C, ranged from 175° to 185°C, and the dielectric constant before poling at room temperature was 2000-8900 within a wafer. After electrical poling, specimens had electromechanical coupling coefficients in rectangular bar mode, k _33´, of 79%-88%, which were larger than for PZT ceramics ( k _33´ < 70%). These PZNT 91/9 single crystals grown by the Bridgman process satisfy the requirements for array-type transducers used in echocardiographic equipment. Results confirm that the Bridgman method is useful for mass-producing large crystals of PZNT 91/9.     

Addition of Aliskiren to Angiotensin Receptor Blocker Improves Ambulatory Blood Pressure Profile and Cardiorenal Function Better than Addition of Benazepril in Chronic Kidney Disease

An altered ambulatory blood pressure (BP) and heart rate (HR) profile is related to chronic kidney disease (CKD) and cardiorenal syndrome. In this study, we examined the effects of aliskiren, when added to angiotensin II type 1 receptor blockers, on ambulatory BP and cardiorenal function in CKD. Thirty-six hypertensive CKD patients were randomly assigned to the aliskiren add-on group (n = 18) or the benazepril add-on group (n = 18). Ambulatory BP and cardiorenal function parameters were measured at baseline and 24 weeks after treatment. Compared with the benazepril group, nighttime systolic BP variability in the aliskiren group was lower after treatment. Albuminuria was decreased in the aliskiren group, but not in the benazepril group. In addition, left ventricular mass index (LVMI) was significantly lower in the aliskiren group than in the benazepril group after treatment. In the aliskiren group, multivariate linear regression analysis showed an association between changes in albuminuria and changes in nighttime systolic BP. Furthermore, there were associations between changes in LVMI and changes in daytime HR variability, as well as between changes in LVMI and changes in plasma aldosterone concentration. These results suggest that aliskiren add-on therapy may be beneficial for suppression of renal deterioration and pathological cardiac remodeling through an improvement that is effected in ambulatory BP and HR profiles.     

Damageless Cu chemical mechanical polishing for porous SiOC/Cu interconnects

Both chemical and mechanical damages to porous SiOC film should be minimized in the Cu-CMP (chemical mechanical polishing) process for the 32-45 nm node Cu interconnect process. This paper first discusses chemical damage that occurs during direct CMP on a porous SiOC film. We found that the k-value increase after direct CMP was caused by the surfactants added to the cleaning chemicals to suppress watermark generation on the hydrophobic SiOC film surface. The surfactants assisted water molecule diffusion into the pores by improving the wettability of the film surface. N₂ annealing after direct CMP removed moisture inside the pores and restored the k-value increase. Second, the paper discusses low-pressure electro-CMP (e-CMP) technology that we developed to reduce mechanical stress on the porous SiOC film. A high removal rate and good planarization performance were obtained by optimizing the cathode area of the electro-cell and carbon material of the e-CMP pad.     

Liquid source chemical vapor deposition of high-dielectric-constant (Ba,Sr)TiO3 films

High-dielectric-constant (Ba, Sr)TiO₃ [BST] films were deposited by the liquid source chemical vapor deposition (CVD) method. The system consisted of a single-wafer, low-pressure thermal CVD reactor, a vaporizer for liquid source materials, and a shower-type gas nozzle head, giving stable BST film deposition on a 6-in. diam. substrate with uniform thickness and uniform chemical composition ratio. The source materials employed were Ba(DPM)₂, Sr(DPM)₂, and TiO(DPM)₂ dissolved in tetrahydrofuran (THF), resulting in conformal step coverage of BST films at lowered substrate temperatures, where DPM denotes dipivaloylmethanate. Moreover, the two-step deposition technique was developed to restart protrusions formed on BST film surfaces at low temperatures, where the BST films consisted of a buffer layer and a main layer; the buffer layer was a layer about 60 Å thick of CVD-BST film annealed in N₂. Thus, the two-step CVD deposition of BST films on Pt and Ru electrodes achieved an equivalent SiO₂ thickness of t_eq ∼ 0.5 nm, a leakage current of J_L ∼ 1.0 × 10⁻⁸ A/cm² (at +1.1 V), and a dielectric loss of tan δ ∼ 0.01 at a total film thickness of 250 Å, along with conformal coverage of 80% for a trench with an aspect ratio of 0.65. Then, for BST films deposited on patterned electrodes 0.24 μm wide, 0.60 μm deep, and 0.15 μm high (each spaced by 0.14 μm), the capacitance was demonstrated to be increased without significant deterioration of the leakage current: the capacitance was increased in comparison with that for films on flat electrodes, by a factor corresponding to the increase in surface area due to sidewalls of storage-node-like pattern features. This capacitance increase reflects the most characteristic advantage of CVD, an excellent step coverage on microscopic pattern features. These electrical properties satisfy the specifications for capacitors for Gb-scale dynamic random access memories (DRAMs), giving a storage capacitance of more than 25 fF/cell for a stacked capacitor having a storage node 0.2 to 0.3 μm high. © 1998 Scripta Technica, Electr Eng Jpn, 125(1): 47–54, 1998     

Physical state of radiation-polymerized polyethylene blends

The physical state of the blends of radiation-polymerized polyethylene with high-density polyethylene was studied. Only one peak was observed in DSC heating curves of the blends quenched from the melt regardless of the each polymer content. In addition, transparency of the high-density polyethylene was improved by melt blending with radiation-polymerized polyethylene. This is a characteristic of high-density polyethylene and radiation-polymerized polyethylene blends different from high-density and low-density polyethylene blends. A new peak and/or a new shoulder, however, appeared in DSC heating curves of the blends with heat treatment at 110°, 120°, and 125°C. These results suggest that the physical state of the blends quenched from the melt is one where the crystallization of the radiation-polymerized polyethylene is high hindered by the presence of high-density polyethylene. The radiation-polymerized polyethylene may remain mainly in a physical state similar to the melt. The haze value of the blends increased with heat treatment. The increase in the haze is caused by change in physical states, such as growth of spherulites and formation of microcrystals and microvoids, by the heat treatment.     

The effect of unilateral nasal patency on the contralateral side

This investigation was designed to verify the possible feed-back mechanism which works to compensate for changes in the nasal volume of one side by the other side. Acoustic rhinometry, with which nasal volume is easily evaluated, was used in this investigation. Acoustic rhinometry was performed at 4 points in time (immediately after, and three, six and nine minutes after, the setting of experimental conditions). This investigation was composed of two studies. In the first study, ten healthy subjects (nine males and one female, 26-49 years of age, mean age 30 years) were evaluated to estimate the effect of decreased unilateral nasal patency upon the other side. In this study, one nasal cavity was occluded with an acryle plug, and the nasal volume of the other side was evaluated by acoustic rhinometry before and after the occlusion. In the second study eight healthy subjects (five males and three females, 24-34 years of age, mean age 29 years) were evaluated to estimate the effect of increased unilateral nasal patency upon the other side. This study covered a period of three days. A small piece of cotton soaked in a vasoconstrictor solution (1/1000 adrenalin or 0.05% naphazolin nitrate) was put in one nasal cavity (the right on the first day, the left on the second day) and the other side was evaluated before and after administration of the solution. On the third day of the control study, a similar piece of cotton soaked in physiological saline solution was put in one nasal cavity, and the other side was evaluated.(ABSTRACT TRUNCATED AT 250 WORDS)     

Divertible and Subliminal-Free Zero-Knowledge Proofs for Languages

Divertible proofs are extensions of interactive proofs in which an active eavesdropper, the warden, makes the prover and the verifier untraceable. The warden is transparent to both the prover and the verifier. With subliminal-free proofs the warden controls subliminal messages. In this paper we present divertible and subliminal-free zero-knowledge proofs for various languages. We consider both graph isomorphism and Received September 1992 and revised September 1995 and May 1997     

Blowing snow at Mizuho station, Antarctica

Blowing snow observations were carried out at Mizuho station, Antarctica, from October to November 2000. A blowing snow observation system including snow particle counters, which can sense not only the number of snow particles, but also their diameters, was situated on a 30 m tower. All instruments worked correctly and the data obtained revealed profiles of mass flux and particle size distributions as a function of the friction velocity. Measurements were compared with a blowing snow model that accounted for most physical processes including aerodynamic entrainment, grain/bed collisions, wind modification, particle size distribution and turbulent fluctuations on the particle trajectories. Simulated and measured results showed close agreement, and the validity of the model was demonstrated. Vertical profiles of horizontal mass flux from saltation to suspension, as well as the particle size distributions were expressed precisely, which could not be achieved using the previous models.