A 16-Mb CMOS SRAM with a 2.3-μm2 single-bit-linememory cell

A novel architecture that enables fast write/read in poly-PMOS load or high-resistance polyload single-bit-line cells is developed. The architecture for write uses alternate twin word activation (ATWA) with bit-line pulsing. A dummy cell is used to obtain a reference voltage for reading. An excellent balance between a normal cell signal line and a dummy cell signal line is attained using balanced common data-line architecture. A newly developed self-bias-control (SBC) sense amplifier provides excellent stability and fast sensing performance for input voltages close to V_CC at a low power supply of 2.5 V. The single-bit-line architecture is incorporated in a 16-Mb SRAM, which was fabricated using 0.25-μm CMOS technology. The proposed single-bit-line architecture reduces the cell area to 2.3-μm² , which is two-thirds of a conventional two-bit-line cell with the same processes. The 16-Mb SRAM, a test chip for a 64-Mb SRAM, shows a 15-ns address access time and a 20-ns cycle time     

Rate Effects on the Stress-Strain Behaviour of Eps Geofoam

The rate-dependency of the stress-strain behavior of EPS (Expanded Polystyrene) geofoam with densities of 19.3 and 28.0 kg/m³ was investigated by performing unconventional unconfined compression tests. A set of monotonic loading (ML) tests were performed at different constant values of vertical (axial) strain rate, ε_v. The ε_v value was stepwise changed many times and several sustained loading (SL) tests were performed during otherwise ML at a constant ε_v in other tests. A number of SL tests were performed during global unload and reload cycles to infer the stress-strain relation when ε_v=0. The elastic properties were evaluated by applying minute unload/reload cycles during otherwise ML. The rate-dependent stress-strain behaviour observed in these tests was described by an elasto-viscoplastic model (i.e., a non-linear three-component model), for which the vertical (axial) stress, σ_v, consists of inviscid and viscous components, σ_v^f and σ_v^v, while ε_v consists of elastic and irreversible components, ε_v^e and ε_v^ir. It is shown that the viscous property of EPS geofoam is of Isotach type in that, under the loading conditions where ε_v^ir is always positive, the current σ_v^v value is a unique function of instantaneous ε_v^ir and ε_v^ir, therefore the strength increases with ε_v. This viscous property was quantified based on the test results and incorporated into the model. The rate-dependent stress-strain behaviour, including the creep behaviour, observed in the experiment is simulated very well by the proposed model. In particular, the fact that the creep strain becomes significant when the sustained σ_v value becomes larger than the inviscid yield vertical stress is well simulated.     

Effect of polytetrafluoroethylene covering of Palmaz stents on the development of intimal hyperplasia in human iliac arteries

PURPOSE: The occurrence of neointimal hyperplasia within a stent may result in restenosis with recurrent symptoms of end-organ ischemia. This study evaluated the potential of a nonporous covering of a stent to function as a barrier to the formation of intrastent neointimal hyperplasia. MATERIALS AND METHODS: Twelve endovascular stent grafts were used to treat 12 high-risk patients with limb-threatening ischemia secondary to long-segment iliac artery occlusion. A 6-mm, thin-walled polytetrafluoroethylene graft was inserted and anchored to the common iliac artery with use of Palmaz stents. Each stent was covered by graft material over one-half of its length. Control angiograms obtained immediately after graft insertion were compared with follow-up angiograms obtained between 4 and 6 months after the initial procedure. On each angiogram, the region of the stent was magnified by 20x to permit computerized luminal diameter measurements. RESULTS: The mean luminal diameter within the stent was significantly greater on the covered (7.7 mm +/- 0.33 standard deviation) compared with the uncovered (6.7 mm +/- 0.85 standard deviation) portions (P < .01). CONCLUSIONS: Partially covered stents are a unique model for assessing the effects of an extrinsic stent covering on arterial healing and myointimal hyperplasia. These data suggest that a relatively nonporous covering of polytetrafluoroethylene may inhibit stent-related restenosis in iliac arteries.     

ASYMPTOTIC EXPANSIONS FOR THE DISTRIBUTION OF AN ESTIMATOR IN THE FIRST-ORDER AUTOREGRESSIVE PROCESS

Abstract. In this paper, two asymptotic expansions for the distribution for an estimator of the parameter in a first-order autoregressive process are derived, according to two situations. Some well known estimators are special cases of the estimator discussed here. The series expansions are carried to terms of order T ^-1.     

Nanoscale Membrane Strips for Benign Sensing of HgII Ions: A Route to Commercial Waste Treatments

The integration of actively‐functional receptors into nanoscale networks outperformed competent detection devices and other ion‐sensing designs. Synthesis of azo chromophores with long hydrophobic tails showed an ecofriendly sensing and an extreme selectivity for divalent mercury analytes. In order to tailor the tip to Hg^II ion‐sensing functionality, we manipulated the chromophores into nanoscale membrane discs, which led to small, easy‐to‐use optical sensor strips. The design of these hydrophobic probes into ordered pore‐based membranes transformed the ion‐sensing systems into smart, stable assemblies and portable laboratory assays. The nanosensor membrane strips with chemical and mechanical stability allowed for reversible, stable and reusable detectors without any structural damage, even under rigorous chemical treatment for several numbers of repeated cycles. The optical membrane strips provided Hg^II ion‐sensing recognition for both cost‐ and energy‐saving systems. Indeed, the synthetic strips proved to have an efficient ability for various analytical applications, targeting especially for on‐site and in situ chemical analyses, and for continuous monitoring of toxic Hg^II ions. On the proximity‐sensing front, these miniaturized nanomembrane strips can revolutionize the consumer and industrial market with the introduction of the probe surface‐mount naked‐eye ion‐sensor strips.     

Inter-laboratory validation studies of biological method for determination of streptomycin in royal jelly

Inter-laboratory validation studies were conducted in 6 laboratories to validate the biological method for determination of streptomycin in royal jelly. Streptomycin spiked at the level of 0.2 and 1.0 ppm was analyzed. Mean recoveries were 89 and 96%, reproducibility relative standard deviations (RSD(R)) were 15.0 and 14.0%, HORRAT(R) values were 0.7 and 0.9. Samples containing residues at the levels of 0.25 and 0.80 ppm were analyzed. Mean recoveries were 113 and 99%, RSD(R) were 15.0 and 10.4%, and HORRAT(R) values were 0.8 and 0.6. The determination limit was 0.1 ppm. These results show that this method has good performance.     

Development of high 1-deoxynojirimycin (DNJ) content mulberry tea and use of response surface methodology to optimize tea-making conditions for highest DNJ extraction

Mulberry 1-deoxynojirimycin (DNJ), a potent α-glucosidase inhibitor, suppresses postprandial blood glucose, thereby possibly preventing diabetes mellitus. At present, mulberry dry teas are commercially supplied as functional foods in many countries, but these products may not provide an effective dose (6 mg DNJ/60 kg human wt) due to their low DNJ content (about 100 mg/100 g of dry wt). Therefore, development of tea with higher DNJ content is desirable. To do this, we investigated distribution of DNJ content and α-glucosidase inhibitory activity in 35 Thai mulberry varieties. DNJ content in young leaves varied among mulberry varieties from 30 to 170 mg/100 g of dry leaves. Varieties having highest DNJ content were Kam, Burirum 60 and Burirum 51. Leaf position affected DNJ content: shoots > young leaves > mature leaves. DNJ concentration and α-glucosidase inhibitory activity were highly correlated (r = 0.84), suggesting that α-glucosidase inhibitory activity of mulberry leaves is mainly due to DNJ. Consequently, high DNJ content mulberry tea was produced from shoots of varieties such as Burirum 60, which contains 300 mg/100 g of dry wt. Tea-making conditions were optimized for highest DNJ extraction using response surface methodology. Approximate 95% of total DNJ in high DNJ content dry tea was extracted when temperature was maintained at 98 °C for 400 s; these conditions could be applicable for preparation of commercial products with high DNJ content. One cup (230 ml, a normal serving) of DNJ-enriched mulberry tea contained enough DNJ (6.5 mg) to effectively suppress postprandial blood glucose.     

Endoleak after endovascular graft repair of experimental aortic aneurysms: does coil embolization with angiographic "seal" lower intraaneurysmal pressure?

PURPOSE: To investigate the relation between endoleaks and intraaneurysmal pressure (IAP) and the effect of coil embolization in the management of endoleaks. METHODS: The infrarenal aorta of a dog (n = 15) was replaced by a polytetrafluoroethylene aneurysm containing a pressure transducer. Group I (n = 4) had untreated aneurysms. Group II (n = 4) had endovascularly excluded aneurysms without an endoleak. Group III (n = 7) had aneurysms excluded by means of grafts with a defect that represented the source of an endoleak. After 4 weeks of follow-up study, the endoleaks in group III dogs were subjected to coil embolization. Systolic IAP was measured daily and expressed as a ratio of systolic blood pressure obtained from a forelimb cuff. Arteriography, duplex ultrasonography, and spiral contrast computed tomography were performed to evaluate endoleaks. RESULTS: In group I, the LAP remained close to systolic blood pressure (ratio of 0.96 +/- 0.06), whereas in group II the IAP ratio showed a decline to 0.34 +/- 0.16 (p = 0.0009 group I versus II). After an initial decrease, the IAP ratio in group III stabilized at 0.75 +/- 0.18 (p = 0.003, group II versus III). Aneurysms with an endoleak remained pulsatile with a pulse pressure of 30 +/- 16 mm Hg, which was less than that of untreated aneurysms (62 +/- 15 mm Hg; p < 0.0001 group I versus III). Arteriography and computed tomography revealed "sealing" of endoleaks after coil embolization, but IAP ratio did not decrease (0.76 +/- 0.14) after coil embolization. CONCLUSIONS: Incomplete endovascular aneurysm exclusion caused by an endoleak fails to reduce IAP ratio and may subject the aneurysm to a continued risk for rupture. Although coil embolization resulted in angiographic and computed tomographic sealing, it failed to reduce IAP ratio.