Preparation of a reticulated polyurethane foam grafted with poly(acrylic acid) through atmospheric pressure plasma treatment and its lysozyme immobilization

We successfully introduced peroxide groups onto the surface of PU(Polyurethane) foam(10 PPI) through one atmospheric pressure plasma treatment and sequentially grafted PAAc(poly(acrylic acid)) on the surface of PU through radical copolymerization. The plasma treatment can generate large amount of peroxides on the surface of PU foam and the peroxide groups act as initiators for further grafting of PAAc in the monomer solution. To introduce large amount of peroxides on the surface of PU foam, we studied the effect of plasma rf-power and treatment time on the maximum grafting of PAAc. Through this study, we found that the optimum plasma treatment condition was the rf-power of 100 W and the treatment time of 100 s. On the other hand, we also studied the effect of graft reaction conditions such as temperature, monomer concentration and reaction time on the change of grafting degree (GD). The GD increased with increasing temperature and increased with reaction time before it leveled off at 3 h after reaction started. At low concentration of AAc, the GD was very low but it showed a maximum at the monomer concentration between 60 and 70%. The surface of the modified PU foam was qualitatively and quantitatively analyzed through the use of FT-IR and weight measurement, respectively. We also observed the surface change before and after plasma induced graft co-polymerization through photo and SEM analysis. Finally, we confirmed that the PU foams grafted with PAAc successfully immobilized lysozyme and other proteins from hen egg white.     

Treatment of dairy wastewater using anaerobic and solar photocatalytic methods

The present study was aimed to treat the dairy wastewater by using anaerobic and solar photocatalytic oxidation methods. The anaerobic treatment was carried out in a laboratory scale hybrid upflow anaerobic sludge blanket reactor (HUASB) with a working volume of 5.9 L. It was operated at organic loading rate (OLR) varying from 8 to 20 kg COD/m³ day for a period of 110 days. The maximum loading rate of the anaerobic reactor was found to be 19.2 kg COD/m³ day and the corresponding chemical oxygen demand (COD) removal at this OLR was 84%. The anaerobically treated wastewater at an OLR of 19.2 kg COD/m³ day was subjected to secondary solar photocatalytic oxidation treatment. The optimum pH and catalyst loading for the solar photochemical oxidation was found to be 5 and 300 mg/L, respectively. The secondary solar photocatalytic oxidation using TiO₂ removed 62% of the COD from primary anaerobic treatment. Integration of anaerobic and solar photocatalytic treatment resulted in 95% removal of COD from the dairy wastewater. The findings suggest that anaerobic treatment followed by solar photo catalytic oxidation would be a promising alternative for the treatment of dairy wastewater.     

Comparison of methods for preventing methanol inhibition in enzymatic production of biodiesel

During the enzymatic production of biodiesel, methanol has a major inhibitory effect on enzyme activity whereas glycerol has a minor effect. Revitalization of the methanol-deactivated enzyme or pre-incubation of enzyme with various chemicals turned out to be unsuccessful. The stepwise feeding of methanol, a widely used conventional method for preventing methanol inhibition, was optimized in terms of the aliquot number and feeding interval to obtain a high conversion rate as well as a high degree of final biodiesel conversion. The use of six feedings of methanol with an equivalent molar ratio of 0.75 at 3-h intervals was found to be the optimal mode for preventing methanol inhibition; a biodiesel conversion rate of approximately 95% could be achieved within 20 h by using this method. Finally, to prevent contact between the undissolved methanol and the enzyme, methanol was pre-dissolved in water or biodiesel and fed to the mixture of soybean oil and the enzyme. This pre-dissolution method completely prevented enzyme inhibition, and a final biodiesel conversion rate of 82.3% was obtained.     

Etch characteristics of silver by inductively coupled fluorine-based plasmas

In this study, thin films of Ag deposited onto glass substrates were etched using inductively coupled fluorine-based plasmas. The effects of various process conditions on the Ag etch characteristics were evaluated to ascertain whether it would be possible to etch patterned Ag films with high etch rates and smooth sidewalls free of involatile etch products. It was found that involatile etch products remained on the substrate when films were etched in CF₄-based gas mixtures possessing either O₂ or N₂ as an additive. However, when Ar was added to either NF₃ or CF₄, a residue-free etch was obtained provided the partial pressure of Ar was no less than 50%. It is proposed that the residue-free Ag etch mechanism involves the formation of silver fluoride, which is physically sputtered by Ar⁺ ions. A Ag etch rate of 160 nm/min with a Ag to photoresist etch selectivity exceeding 1.1 was achieved with an inductive power of 1500 W, a d.c. bias voltage of −180 V and a chamber pressure of 0.8 Pa with 50-50 CF₄/Ar partial pressures obtained with 60 sccm CF₄/60 sccm Ar flows. In addition, these conditions produced smooth Ag sidewall etch profiles.     

The type II peroxiredoxin gene family of the mouse: molecular structure, expression and evolution

The central effect of 3-morpholinosydnonimine, a nitric oxide donor, on the sympatho-adrenomedullary system was investigated in urethane-anesthetized rats. Intracerebroventricular administration of 3-morpholinosydnonimine (100, 250 and 500 microg/animal) induced a marked elevation of adrenaline levels and a slight elevation of noradrenaline levels in the plasma. These 3-morpholinosydnonimine (250 microg/animal)-induced elevations of catecholamines were abolished by intracerebroventricular treatments with 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-l-oxyl 3-oxide (750 microg/animal), a nitric oxide scavenger, and indomethacin (500 microg/animal), a cyclo-oxygenase inhibitor, but not with superoxide dismutase (250 units/animal), a superoxide anion scavenger. Furthermore, the 3-morpholinosydnonimine (250 microg/animal)-induced elevation of plasma adrenaline levels was abolished by intracerebroventricular treatments with thromboxane A2 synthase inhibitors [furegrelate (100, 250 and 1000 microg/animal) and carboxyheptyl imidazole (500 microg/animal)], and also with thromboxane A2 receptor blockers [(+)-S-145 (100, 250 and 1000microg/animal) and SQ29548 (8microg/animal)]. The elevation of noradrenaline levels was, however, not attenuated by these thromboxane A2-related test agents. The present results indicate that nitric oxide but not peroxynitrite markedly activates central adrenomedullary outflow. Thromboxane A2 in the brain is probably involved in this central activation of adrenomedullary outflow.     

Highly reliable ferroelectric memories using BLT thin films and robust integration schemes

We report on highly reliable characteristics of 1-Mb ferroelectric memories based on 0.35-/spl mu/m CMOS technology ensuring ten-year retention and imprint at 175/spl deg/C, which have been successfully developed for the first time. This excellent reliability resulted from newly developed [Bi/sub 1-x/La/sub x/]/sub 4/Ti/sub 3/O/sub 12/ (BLT) ferroelectric films with superior reliability performance at high temperatures, and also resulted from robust integration schemes free from ferroelectric degradation due to process impurities such as moisture and hydrogen.     

An investigation of the high-frequency limit of a miniaturizedcommercial voltage-controlled oscillator used in 900-MHz-bandmobile-communication handset

The 900-MHz-band voltage-controlled oscillator (VCO) currently used in a commercial mobile-communication handset has the features of light weight, small size, low phase noise, and low DC current consumption. This paper investigates the problems that may occur when these types of VCO's are employed in next-generation high-frequency mobile-communication handsets. The results show that oscillation may not commence above frequency f_T/² √(R_eq /T_bb), which is significantly below the f_max of the device itself, due to the effects of the circuit elements. In addition, a new formula is proposed which provides a practical guideline for selection of the active devices. The procedure for extraction of the small-signal model required by the proposed formula is also described in detail. The results obtained with the formula are in good agreement with those obtained from the measured S-parameters     

NOT and NAND logic circuits composed of top-gate ZnO nanowire field-effect transistors with high-k Al(2)O(3) gate layers

Electrical characteristics of NOT and NAND logic circuits fabricated using top-gate ZnO nanowire field-effect transistors (FETs) with high-k?Al(2)O(3) gate layers were investigated in this study. To form a NOT logic circuit, two identical FETs whose I(on)/I(off) ratios were as high as ～10(8) were connected in series in a single ZnO nanowire channel, sharing a common source electrode. Its voltage transfer characteristics exhibited an inverting operation and its logic swing was?98%. In addition, the characteristics of a NAND logic circuit composed of three top-gate FETs connected in series in a single nanowire channel are discussed in this paper.