Cost reduction of polycrystalline diamond compact bits through improved durability

This work reports the results of laboratory drilling tests conducted in order to measure improvements due to design and cutter modifications on PDC bits intended for use in geothermal well drilling. These tests, using 142.88 mm-dia. PDC full face bits, concentrated on improvements in bit life and cost performance. The tests were performed using granite drilling samples and a laboratory drilling machine at atmospheric conditions. The results from changes in bit and cutter shape are reported in the work.     

Influence of alkylpyridine additives in electrolyte solution on the performance of dye-sensitized solar cell

The influence of alkylpyridines additive to an I⁻/I₃⁻ redox electrolyte in acetonitrile on the performance of a bis(tetrabutylammonium)cis-bis(thiocyanato)bis(2,2′-bipyridine-4-carboxylic acid, 4′-carboxylate)ruthenium(II) dye-sensitized TiO₂ solar cell was studied. I–V measurements were performed using more than 30 different alkylpyridines. The alkylpyridine additives showed a significant influence on the performance of the cell. All the additives decreased the short-circuit photocurrent (J_sc), but most of the alkylpyridines increased the open-circuit photovoltage (V_oc) and fill factor (ff) of the solar cell. The results of the molecular orbital calculations suggest that the dipole moment of the alkylpyridine molecules correlate with the J_sc of the cell. These results also suggest that both the size and ionization energy of pyridines correlate with the V_oc of the cell. Under AM 1.5 (100 mW/cm²), the highest solar energy conversion efficiency (η) of 7.6% was achieved by using 2-propylpyridine as an additive, which was more effective than the previously reported additive, 4-t-butylpyridine.     

Switched-Capacitor Track-and-Hold Amplifiers With Low Sensitivity to Op-Amp Imperfections

This paper describes high-precision switched-capacitor (SC) track-and-hold amplifier (THA) stages. They use a novel continuous-time correlated double sampling (CDS) scheme to desensitize the operation to amplifier imperfections. Unlike earlier predictive-CDS amplifiers, the circuits do not need a sampled-and-held input signal for their operation. During the tracking period, an auxiliary continuous-time signal path is established, which predicts the output voltage during the holding period. This allows accurate operation even for low amplifier gains and large offsets over a wide input frequency range. Extensive simulations were performed to compare the performance of the proposed THAs with earlier circuits utilizing CDS. The results verify that their operation is far more robust than that of any previously described SC amplifiers     

AlAs/GaAs Schottky-collector resonant-tunnel-diodes

The Schottky-collector resonant-tunnel-diode (SRTD) is an resonant-tunnel-diode with the normal N⁺ collector layer and ohmic contact replaced by direct Schottky contact to the space-charge layer, thereby eliminating the associated parasitic series resistance Rins. By scaling the Schottky collector contact to submicron dimensions, the device periphery-to-area ratio is increased, decreasing the periphery-dependent components of the parasitic resistance, and substantially increasing the device's maximum frequency of oscillation. We report measured d.c. and microwave parameters of planar SRTDs fabricated with 1 μm-geometries in AlAs/GaAs.     

Clinical studies on vancomycin in the treatment of MRSA infection

We evaluated the effectiveness and safety of vancomycin (VCM) alone and in combination with beta-lactam antibiotics in the treatment of MRSA infections, and obtained the following results: 1. Effectiveness. (1) In cases of MRSA infections alone, the improvement rate was 71.4% (5/7 patients) with VCM alone and 77.8% (35/45) with VCM in combination with beta-lactam antibiotics. (2) In cases of polymicrobial infections, few cases were treated with VCM alone, but the improvement rate in combination use with beta-lactam antibiotics was 71.8% (28/39). 2. Bacteriological effect. (1) In cases of single infection with MRSA, the rate of bacterial eradication was 71.4% (5/7) with VCM alone and 68.2% (30/44) with VCM in combination with beta-lactam antibiotics. (2) In cases of polymicrobial infections, few cases were treated with VCM alone, but the rate of bacterial eradication in combination use with be ta-lactam antibiotics was 63.2% (24/38) against MRSA and 31.6% (12/38) against polymicrobial agents including MRSA. 3. Safety. Occurrences of adverse reactions and abnormal laboratory test values when VCM was used alone or when it is used in combination with another drug were about the same in these uses. As a whole, advance reactions were observed in 16 patients (9.5%). Main adverse reactions were whole body redness, drug eruption, and rash etc. Abnormal laboratory test values were observed mainly in hepatic functions, and renal functions. 4. VCM concentrations in blood was determined in 38 patients. Doses of 0.5 g and 1.0 g of VCM was administered by intravenous drip infusion over a period of 1 to 2 hours, and mean blood concentrations 1 to 2 hours after the completion of drip infusion were 25.4 micrograms/ml and 14.4 micrograms/ml, respectively. 5. Synergic effects between VCM and other antibiotics tested were observed in FIC index against all of the six MRSA strains isolated from six patients, and the clinical effects of improvement or better were obtained against five of them.     

Building a CIM system for compound plant: Utilization of distributed processing system

The position of a production management system in a computer-integrated manufacturing (CIM) system is to serve as the nucleus of the plant CIM system that connects the plant production to other departments such as marketing, research and development, and distribution departments. A production management system that integrates the flow of goods with information in a plant, and thus manages production in it, was developed as the first step toward application of CIM to a powder plant. The method of building a distributed system is one way to build a CIM system. This method creates a system in the required function units, which are connected by a network to expand the system function. It offers advantages in extensibility, flexibility, and rapid implementation.     

Prevention by inhibitors of arachidonic acid cascade of liver carcinogenesis, cirrhosis and oxidative DNA damage caused by a choline-deficient, L-amino acid-defined diet in rats

Effects of inhibitors of arachidonic acid (AA) cascade on the development of fatty liver, cirrhosis, glutathione S-transferase placental form (GST-P)-positive preneoplastic nodules, neoplastic nodules and generation of 8-hydroxydeoxyguanosine (8-OHdG), caused by a choline-deficient, L-amino acid-defined (CDAA) diet, were examined in Fischer 344 male rats by feeding CDAA diet supplemented with the inhibitors for 12 and 30 weeks. None of the inhibitors affected fatty liver. Among cyclooxygenase (COX) inhibitors, an irreversibly acting acetylsalicylic acid and a long-acting piroxicam, and to a much lesser extent the short-acting ibuprofen but not indomethacin, inhibited the development of cirrhosis, GST-P-positive and neoplastic nodules and generation of 8-OHdG. A phospholipase A2 inhibitor p-bromophenacylbromide (BPB) also exerted similar but lesser extent of inhibitory effects. Lipoxygenase inhibitors quercetin and nordihydroguiaretic acid inhibited GST-P-positive nodules but not cirrhosis or 8-OHdG. Present results suggest that perturbed AA cascade, particularly augmented COX pathway, might play key roles in the causation of liver lesions in the CDAA diet model.     

An autopsy case of adult onset glycogen storage disease type Ia

A 3-week tour of the Far East was coordinated by Dr. Ronald DeWald, senior travelling fellow appointed by the Scoliosis Research Society. Three junior fellows appointed by the Education Committee of the Scoliosis Research Society accompanied him. The purpose of this fellowship was to develop a comaraderie and exchange ideas, thoughts, and experiences in the field of spinal deformity.     

Problems in pharmacological evaluation of patients with paroxysmal atrial fibrillation: clinical analysis of more than 100 consecutive patients

To address the problems of pharmacological evaluation in paroxysmal atrial fibrillation (PAf), we interviewed 108 consecutive patients with documented PAf regarding symptoms, frequency and trigger factors of PAf and analyzed the 24-hour ambulatory electrocardiographic monitoring (Holter monitoring) records in relation to symptoms. Twenty-nine patients were totally asymptomatic, while 79 patients were symptomatic of which 49 patients had obvious trigger factors. PAf was documented by Holter monitoring in 22 of 79 symptomatic patients. On analysis of PAf-documented 25 Holter monitoring records, the patients checked event marks as PAf in only 20 of 155 PAf episodes. Six episodes of 26 event marks that patients thought to be PAf proved to be premature atrial or ventricular contractions. Nine patients in whom PAf persisted for more than 24 hours became asymptomatic. Patients suitable for pharmacological evaluation constituted about one-fifth of the PAf patients in our consecutive study. Even with the selection of these patients, pharmacological evaluation based on symptoms is difficult because disappearance of PAf may be associated with persistent atrial fibrillation.