Polymer-derived β-SiAlON:Eu2+ phosphors

A series of β-SiAlON:Eu²⁺ phosphors were synthesized from single-source precursors, perhydropolysilazane chemically modified with Al(OCH(CH₃)₂)₃, AlCl₃, and EuCl₂. The single-source precursors were converted to β-SiAlON:Eu²⁺ phosphors by pyrolysis under flowing N₂ or NH₃ at 1000°C, followed by heat treatment at 1800°C under an N₂ gas pressure at 980 kPa. By varying the molar ratio of the chemical modifiers, β-SiAlON:Eu²⁺ with the compositions close to the theoretical ones expressed as Si_6−zAl_zO_z−2yN_8−z+2y:yEu²⁺ were synthesized, where the z values and Eu²⁺ contents were controlled in the ranges of .44–.78 and .35–1.48 mol%, respectively. The polymer-derived β-SiAlON:Eu²⁺ phosphors exhibited green emission under excitation at 460 nm attributed to the 4f⁷–4f⁶(7f³)5d¹ transition of dopant Eu²⁺. High-angle annular dark-field-scanning transmission microscopy analysis confirmed that the doped-Eu²⁺ existed interstitially within the channels along the c axis of host β-SiAlON. Compared with the conventional powder metallurgy route, the polymer-derived ceramic route in this study offers some advantages in the grain growth of host β-SiAlON and photoluminescence properties in terms of green emission intensity under excitation at 460 nm, and the highest intensity was achieved for the polymer-derived β-SiAlON:Eu²⁺ with z = .64 and .37 mol% Eu²⁺.     

Development of a strain for efficient degradation of polychlorinated biphenyls by patchwork assembly of degradation pathways

Rhodococcus jostii RHA1 accumulates chlorobenzoates (CBA) during the degradation of polychlorinated biphenyls (PCBs). CBA degradation is considered one of the rate-limiting steps in the complete degradation of PCBs. To reduce the accumulation of CBAs, the upper pathway enzyme genes for PCB degradation of RHA1 were introduced into a CBA-degrading bacterium, Burkholderia sp. NK8. The resulting recombinant strain exhibited no biphenyl 2,3-dioxygenase (BphA) activity encoded by bphAaAbAcAd genes, which encode the large and small subunits of the terminal oxygenase component and the ferredoxin and reductase subunits responsible for electron transfer from NADH to the large subunit. The remaining enzyme genes involved in the transformation of biphenyl to benzoate, bphB2C1D1, which encode dehydrogenase, ring-cleavage dioxygenase and hydrolase, conferred activities to NK8. To obtain the BphA activity of RHA1 in NK8, sets of BphA genes were constructed by combining the bphAaAbAcAd genes of RHA1 and bphA3A4 of Pseudomonas pseudoalcaligenes KF707, encoding the ferredoxin and reductase subunits. Hybrid derivatives of BphA containing the KF707 bphA3 conferred BphA activity to NK8, and a derivative containing the RHA1 bphAaAb and KF707 bphA3A4 genes exhibited the highest BphA activity. A plasmid containing the RHA1 bphAaAb and KF707 bphA3A4 genes plus the RHA1 bphB2C1D1 genes was constructed and introduced into NK8. The resulting recombinant strain efficiently degraded 2-, 3- and 4-chlorobiphenyls with an apparent reduction in CBA accumulation in comparison to the recombinant mutant strain, which had an insertion in the cbeA gene to inactivate CBA dioxygenase.     

Application of microalgae hydrolysate as a fermentation medium for microbial production of 2-pyrone 4,6-dicarboxylic acid

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A 500-MHz pipelined burst SRAM with improved SER immunity

This paper describes a 0.25-μm, 64 K×36 bit pipelined burst SRAM using a 6.156-μm² cell. It realizes over 500-MHz operation using a lower cost double metal process, Internal 16 K×144 organization by T-shaped bit line array reduces 20% of latency, 20% of active power, and 8.5% of die size. The low power also enables us to use lower cost thin quad flat type packages. Our solution to the soft error problem, a shallow triple well structure and four-transistor cell with stacked capacitor, improved soft error rate by 3.5 orders of magnitude compared with the conventional SRAM cell     

pH measurement in the vicinity of a cathode evolving hydrogen gas using an antimony microelectrode

An antimony microelectrode was prepared by quenching a molten Sb–Sb2O3 mixture (2% Sb2O3). The local pH in the vicinity of a cathode evolving hydrogen gas was directly measured using the microelectrode. The local pH during electrolysis of KCl-glycine aqueous solutions was increased by proton consumption; however, the increment decreased with increasing concentrations of glycine, a buffering agent. The diffusion-limiting current density of hydrogen evolution involving proton reduction was controlled by the concentrations of the proton-donating species: protonated-glycine +H3NCH2COOH and H3O+ ions. A plot of the current density against the sum of the concentrations gives a single straight line passing through the origin. The phenomena are discussed in terms of electrodeposition processes of base metals.     

Adenovirally expressed basic fibroblast growth factor rescues photoreceptor cells in RCS rats

OBJECTIVE: To examine the efficacy of an antileukocyte adhesion antibody (anti-CD18) as an adjuvant for delayed (2 hours and 4 hours) thrombolytic therapy (recombinant human tissue plasminogen activator [rt-PA]) in middle cerebral artery occlusion (MCAO) in rats. BACKGROUND: Thrombolytic therapy with rt-PA is limited in its application by a short therapeutic window. METHODS: Male Wistar rats were subjected to MCAO by a single fibrin-rich clot. The rats were assigned to the following experimental groups: Experiment 1 (treatment 2 hours after embolization), 1) rt-PA, 2) anti-CD18 antibody, 3) rt-PA and anti-CD18 antibody, 4) immunoglobulin (Ig) G, and 5) vehicle; Experiment 2 (treatment 4 hours after occlusion), 1) rt-PA alone, 2) rt-PA and anti-CD18 antibody, and 3) nontreated control group. Neurologic deficits, infarction volume, hemorrhage, and brain myeloperoxidase (MPO) immunoreactivity were measured. Results: Administration of rt-PA and anti-CD18 antibody 2 hours later reduced significantly (p < 0.05) the infarct volume and improved neurologic deficits compared with the vehicle-treated group. Treatment with rt-PA alone improved neurologic deficits significantly and reduced mean infarct volume compared with the vehicle-treated group. However, treatment with anti-CD18 antibody neither reduced infarct volume nor improved neurologic deficits compared with the IgG-treated group. The combination of rt-PA and anti-CD18 antibody treatment at 4 hours reduced significantly the infarct volume and MPO immunoreactive cells compared with rt-PA treatment alone at 4 hours, and reduced neurologic deficits compared with rt-PA treatment alone and compared with the nontreated animals. CONCLUSIONS: The combination of antileukocyte adhesion antibody and thrombolytic therapy may increase the therapeutic window for the treatment of stroke.     

Effects of radioactive fallout on the pregnant woman and the fetus

The levels of ⁹⁰Sr and ¹³⁷Cs in human placenta, fetus and diet were determined by radiochemical methods during the period from March 1966 to December 1968. The possible effects of these radionuclides on the pregnant woman and the fetus were discussed. The metabolic characteristics of both ⁹⁰Sr and ¹³⁷Cs were also discussed on the basis of estimates of discrimination factors and observed ratios of these radionuclides.

As a result of the analyses, the dose rate to the human placenta resulting from deposition of ⁹⁰Sr in the organ was estimated at about 0.003 mrem/month and that of ¹³⁷Cs at about 0.013 mrem/month. The dose rate to the total body resulting from the body burden of these radionuclides in the mother was estimated at about 0.012 mrem/ month. These values are much smaller than the monthly dose from ⁴⁰K normally existing in the body.

It was rather difficult to draw definitive conclusions concerning the possible correlation between the ⁹⁰Sr fallout and the annual changes of infant mortality rates in Japan.     

Persistence and partitioning of eight selected pharmaceuticals in the aquatic environment: Laboratory photolysis, biodegradation, and sorption experiments

We selected eight pharmaceuticals with relatively high potential ecological risk and high consumption—namely, acetaminophen, atenolol, carbamazepine, ibuprofen, ifenprodil, indomethacin, mefenamic acid, and propranolol—and conducted laboratory experiments to examine the persistence and partitioning of these compounds in the aquatic environment. In the results of batch sunlight photolysis experiments, three out of eight pharmaceuticals—propranolol, indomethacin, and ifenprodil—were relatively easily photodegraded (i.e., half-life < 24 h), whereas the other five pharmaceuticals were relatively stable against sunlight. The results of batch biodegradation experiments using river water suggested relatively slow biodegradation (i.e., half-life > 24 h) for all eight pharmaceuticals, but the rate constant was dependent on sampling site and time. Batch sorption experiments were also conducted to determine the sorption coefficients to river sediments and a model soil sample. The determined coefficients (K_d values) were much higher for three amines (atenolol, ifenprodil, and propranolol) than for neutral compounds or carboxylic acids; the K_d values of the amines were comparable to those of a four-ring polycyclic aromatic hydrocarbon (PAH) pyrene. The coefficients were also higher for sediment/soil with higher organic content, and the organic carbon-based sorption coefficient (log K_oc) showed a poor linear correlation with the octanol-water distribution coefficient (log D_ow) at neutral pH. These results suggest other sorption mechanisms—such as electrochemical affinity, in addition to hydrophobic interaction—play an important role in sorption to sediment/soil at neutral pH.     

Hemodynamic characterization of YM435, a novel dopamine DA1 receptor agonist, in anesthetized dogs

In previous studies on experimental renal failure, hypertrophy of cardiomyocytes, diminished capillarization, and increased intercapillary distances had been observed, abnormalities that will expose the heart to reduced ischemia tolerance. It has not been established, however, whether such structural alterations are unique for the heart (eg, as a consequence of left ventricular hypertrophy) or are demonstrable in other tissues as well. Clarification of this point is important to test hypotheses on some potential mechanisms for cardiac undercapillarization. To address this issue further, we compared capillary length density (by stereologic techniques) in perfusion-fixed skeletal muscle (m. psoas) and hearts of subtotally nephrectomized (SNX) rats with moderate renal failure to those in sham-operated pair-fed controls. The duration of renal failure was 8 weeks. SNX rats had significantly higher mean systolic blood pressure (128 mm Hg v 109 mm Hg), serum creatinine, and urea levels. Despite pair feeding, the mean body weight was significantly lower in the SNX rats (409 g v 471 g), but the left ventricular weight to body weight ratio tended to be higher than in the sham-operated controls (2.39 mg/g v 2.13 mg/g). In the heart, myocyte mean cross-sectional area (675 +/- 112 microm2 v 545 +/- 111 microm2) and volume density of nonvascular interstitial tissue (3.47 +/- 1.04 v 1.33 +/- 0.22) were significantly higher in the SNX rats than in the controls. In parallel, myocardial capillary length density was significantly reduced after subtotal nephrectomy (3,036 +/- 535 mm/mm3 v 3,916 +/- 615 mm/mm3). In contrast, in skeletal muscle, myocyte cross-sectional area (3,109 +/- 783 microm2 v 3,042 +/- 639 microm2), capillary length density (718 +/- 248 mm/mm3 v 717 +/- 184 mm/mm3), and three-dimensional capillary fiber ratio (2.10 +/- 0.26 v 2.13 +/- 0.4) were similar in SNX and control rats. These data document a selective defect of capillarization in the heart of animals with moderate renal failure, pointing to tissue-specific abnormalities of cardiac capillarogenesis.