A tunable CMOS-DRAM voltage limiter with stabilized feedbackamplifier

The authors present two developments for a CMOS-DRAM voltage limiter: a precise internal-voltage generator, and a stabilized driver composed of a feedback amplifier with compensation. The voltage limiter's features include generating a PMOS-V_T difference, being capable of voltage tuning with fuse trimming, and compensation in the driver circuit through zero insertion. It provides a voltage impervious to supply-voltage and substrate-voltage boundings, temperature variation, and process fluctuation, while ensuring the feedback-loop stability with a phase margin of 55° for a time-dependent load of DRAM circuit. The proposed circuits are experimentally evaluated through their implementation in a 16-Mb CMOS DRAM. A temperature dependency of 1.4 mV/°C and a voltage deviation within ±10% for process fluctuation are achieved. The voltage is stabilized within ±3% for V_CC bounce and ±10% for memory operation     

Error tracking mode AC current waveform control method for three-phase self-commutated voltage source power converters

A novel design theory for a three-phase self-commutated power conversion system (PCS) to perform as an ac current source is proposed. In this new ac current waveform control method termed error tracking mode, the switching instructions of main devices are decided only by the error function of ac current at every data sampling time that comes in a constant period. The performance is theoretically evaluated. Simulation by SPICE also is executed and the characteristics are inspected. Error tracking mode has the following attractive features. It can treat two arbitrary current waveforms as target functions of two-phase arbitrary ac currents. The error between actual ac current value and the objective function value can be controlled and guaranteed to be less than an arbitrary value, which is given beforehand. All control components can be digitized. The minimum continuous on and off time of main devices is guaranteed in advance. No special starting control is necessary because actual ac currents are guaranteed to start tracking the target functions automatically. Error tracking mode makes contributions to improve precision in current control and to reduce current harmonics of self-commutated voltage source power converters.     

Two-dimensional DNAPL migration affected by groundwater flow in unconfined aquifer

The dense non-aqueous phase liquid (DNAPL) migration process was experimentally investigated in a laboratory-scale tank (150 cm width, 82.5 cm height, and 15 cm depth) to assess a site characterization on DNAPL contamination below a groundwater table. The heterogeneous ground of the tank model consisted of Toyoura sand (hydraulic conductivity, k = 1.5 x 10(-2) cm/s for void ratio, e = 0.62) and silica #7 sand (k = 2.3 x 10(-3) cm/s for e = 0.72). A series of experiments was carried out with or without lateral groundwater flow. Hydrofluoroether was used as a representative DNAPL. The main results obtained in this study are as follows: (1) the DNAPL plume does not invade into the less permeable soil layer with higher displacement pressure head; (2) the DNAPL plume migrates faster with lateral groundwater flow than without it; (3) lateral groundwater flow does not affect lateral DNAPL migration; rather, it promotes downward migration; and (4) pore DNAPL pressure without groundwater flow is higher than that with it. The above experimental results were compared with numerical analysis. The fundamental behaviors of DNAPL source migration observed experimentally are expected to be useful for assessing the characteristics of two-dimensional DNAPL migration in an aquifer.     

Development of a universal ellipsoidal mirror device for fluorescence detected circular dichroism: elimination of polarization artifacts

We have developed an ellipsoidal mirror fluorescence detected circular dichroism (FDCD) device with enhanced detection sensitivity that eliminates the polarization artifact; this is applicable to samples with strongly polarized fluorescence. The device, JASCO FDCD465, has an ellipsoidal mirror structure with a framework consisting of three mirrors (one elliptical and two plane mirrors) that maximally collects light in the FDCD. All assemblies on the device including the ellipsoidal mirror, cylindrical cell, and photomultiplier tube (PMT) are aligned on the chamber-fitting sample mount as an attachment compatible with a standard CD spectropolarimeter. The new FDCD465 device eliminates the polarization artifact caused by anisotropic distribution of the emitted light. It represents a convenient, reliable, and sensitive FDCD attachment to the JASCO J-800 CD spectrometer series that can be used under both isotropic and photoselected conditions.     

Cod lipids,solvent systems and the effect of fatty acid chain length and unsaturation on lipid class analysis by Iatroscan TLC-FID

The chromatographic behavior of molecular species of free fatty acids, triglycerides, sterol esters and wax esters on Chromarods-SII was investigated in four developing solvent systems of different polarities. In accordance with previous reports it was observed that molecular species within a lipid class are partially separated according to the chain length and degree of unsaturation of the acyl groups. The separation is more affected by the degree of unsaturation than the chain length, especially in nonpolar solvent systems. In polar solvent systems the separation within a lipid class is less efficient; a slight separation according to the chain length was observed, and the degree of unsaturation had little or no influence. The partial separation of molecular species within a class leads to the superimposing of certain lipid classes, for example glyceryl ethers and highly unsaturated fatty acids of marine origin. This poses a potential problem in identification of Iatroscan peaks. However, with totally hydrogenated marine lipid samples a complete separation of the lipid classes was achieved when developed in a nonpolar solvent system. It is proposed that at least two kinds of authentic standards varying in the degree of unsaturation and chain length should be used for the identification of the peaks of natural lipid samples of unknown composition, and that total hydrogenation be applied to improve separations and ensure sample stability, and probably to improve quantitation accuracy.     

Pitavastatin ameliorates severe hepatic steatosis in aromatase-deficient (Ar−/−) mice

Tamoxifen is a potent antagonist of estrogen, and hepatic steatosis is a frequent complication in adjuvant tamoxifen for breast cancer. Impaired hepatic FA β-oxidation in peroxisomes, microsomes, and mitochondria results in progression of massive hepatic steatosis in estrogen deficiency. This impairment, although latent, is potentially serious: About 3% of the general population in the United States is now suffering from nonalcoholic steatohepatitis associated with obesity and hyperlipidemia. Therefore, in the present study we tried to restore impaired hepatic FA β-oxidation by administering a novel statin, pitavastatin, to aromatase-deficient (Ar−/−) mice defective in intrinsic estrogen synthesis. Northern blot analysis of Ar−/− mice liver revealed a significant restoration of mRNA expression of essential enzymes involved in FA β-oxidation such as very long fatty acyl-CoA synthetase in peroxisome, peroxisomal fatty acyl-CoA oxidase, and medium-chain acyl-CoA dehydrogenase. Severe hepatic steatosis observed in Ar−/− mice substantially regressed. Consistent findings were obtained in the in vitro assays of FA β-oxidation activity. These findings demonstrate that pitavastatin is capable of restoring impaired FA β-oxidation in vivo via the peroxisome proliferator-activated receptor-α-mediated signaling pathway and is potent enough to ameliorate severe hepatic steatosis in mice deficient in intrinsic estrogen.     

Preparation and properties of new tetrafunctional amphoteric surfactants bearing amino,carboxyl, and hydroxyl groups and an ether bond

New amphoteric surfactants of N-(3-alkoxy-2-hydroxypropyl)-N-(2-hydroxyethyl)-β-alanine (APA) have been synthesized. The fundamental surface-active properties (critical micelle concentration and isoelectric point) and hemolysis tests were also investigated to examine the effects of differences in chain length of the alkoxy moiety. The hemolysis result of APA exhibited low constant values irrespective of the alkyl chain length. The amphoteric APA surfactant was confirmed to have a mild effect on human microorganisms and to possess excellent surface-active properties. In addition, a speculative model of micelle configuration was estimated by semiempirical molecular orbital simulations.     

Elevated serum soluble Fas ligand in natural killer cell proliferative disorders

We evaluated the serum level of soluble Fas ligand (sFasL) in patients with natural killer lymphocyte proliferative disorders (NK- LPD). The serum sFasL level was elevated in neoplastic groups of aggressive NK leukaemia, indolent NK leukaemia and NK lymphoma, all of which contained clonal EBV-DNA. In NK leukaemia the serum sFasL level was significantly higher than that found in others. However, it was not elevated in the patients with reactive NK-LPD and in one patient with NK leukaemia in remission. These findings indicate that the serum sFasL level is a useful indicator in evaluating disease activity.     

Synergistic induction of DNA strand breakage by cigarette tar and nitric oxide

Cigarette smoking is a major cause of human cancer at a variety of sites, although its carcinogenic mechanisms remains unestablished. Cigarette smoke can be divided into two phases, gas phase and particulate matter (tar). Both phases contain high concentrations of oxidants and free radicals, especially nitric oxide (NO) and nitrogen oxides in the gas phase and quinone/hydroquinone complex in the tar. We have found that incubation of pBR322 plasmid DNA with aqueous extracts of cigarette tar and a NO-releasing compound (diethylamine NONOate) caused synergistic induction of DNA single-strand breakage, whereas either cigarette tar alone or NO alone induced much less strand breakage. This synergistic effect of cigarette tar and NO on DNA strand breakage was prevented by high concentrations of superoxide dismutase, carboxy-PTIO (an NO-trapping agent) or N-acetylcysteine, whereas hydroxyl radical scavengers such as dimethylsulfoxide, ethanol and D-mannitol did not show inhibitory effects. Possible mechanisms for this synergistic effect mediated by cigarette tar and NO are proposed, including involvement of peroxynitrite, which is a strong oxidant and nitrating agent formed rapidly by the reaction between NO and O2.-. NO is present in the gas phase of smoke and may be formed by a constitutive or inducible NO synthase in the lung, whereas O2.- is generated by auto-oxidation of polyhydroxyaromatic compounds such as catechol and 1,4-hydroquinone present in cigarette tar. Thus, potent reactive species including peroxynitrite formed by the interaction between cigarette tar and NO may play an important role in smoking-related diseases including lung cancer.