Synthesis of NAD polystyrene microspheres and application as a carrier of glucoamyrase immobilization

Polystyrene microspheres with a small amount of acrylic acid (200 : 1) incorporated were synthesized by nonaqueous phase dispersion (NAD) polymerization to investigate the feasibility of use as a carrier for immobilized enzyme. Seeded emulsion polymerization was then carried out to obtain larger cross-linked polystyrene spheres, the structure of which was expected to yield a favorable environment to keep the original activity of the immobilized enzyme. Glucoamylase, a particular enzyme catalyzing the hydrolysis of oligosaccharides to glucose, was immobilized through peptide bonding using a carbodiimide activating agent. Thirty percent of the enzyme activity at maximum was retained relative to free glucoamylase. The immobilized enzyme remained active after 4 months, although its poor resistance to heat was not improved. © 1994 John Wiley & Sons, Inc.     

Automated synthesis of radiopharmaceuticals for positron emission tomography: an apparatus for [1-11C] labeled carboxylic acid

A fully automated apparatus for the synthesis and formulation of short-lived ¹¹C (t_1/2 = 20 min)-labeled carboxylic acids for positron emission tomograpy (PET) has been developed. Injectable solutions of [1-¹¹C]acetic acid, [1-¹¹C]octanoic acid and [1-¹¹C]palmitic acid wilh radioactivities of 6.36-8.29 GBq, 0.070-1.43 GBq and 0.42-0.89 GBq were obtained. The preparation time was under 40 min after the end of bombardment. An automatic washing function means that labeled compound of the same or different kinds can be produced several times a day without any maintenance of the system. The control system is sited away from the ‘hot laboratory’, so operator exposure to radiation is minimized.     

Molecular orbital study of pyrolytic carbons based on small cluster models

Molecular orbital calculations are applied to the Raman scattering and ESR of pyrolytic carbons on the basis of small cluster models. The E_2g and A_1g modes of C-C stretching vibrations of coronene, hexabenzocoronene, and circumcoronene, which belong to D_6h carbon clusters, are shown to appear around the 1550 cm⁻¹ and 1360 cm⁻¹ bands, respectively. The unpaired electrons observed in pyrolytic carbons are attributed to the bond-alternation defects on odd-numbered carbon clusters that are more easily mobile than those of trans-polyacetylene.     

Wear and bending strain characteristics of artificial hip joint with non-glued stem and UHMWPE femur

The aim of this study was to experimentally assess the effects of loosening between the stem of a cementless artificial hip joint and the femur on the wear and bending strain of the stem during the initial embedding term. The behavior of an ultrahigh-molecular-weight polyethylene (UHMWPE) femur model with this stem was then investigated. The interface between the stem and the UHMWPE femur model is either glued or not glued. Evaluation of differences between the two gluing conditions was conducted using testing equipment equipped with a reciprocating stage for an artificial hip joint. Total wear between the Co–Cr alloy head and UHMWPE socket was measured using a laser displacement meter installed in the axis direction on a main shaft of the tester. We measured the bending strain waveforms of the flexural direction, which was shown by three strain gauges on the upper, middle and lower part of the stem. The present results indicate that the rate of wear was markedly greater for non-glued stems than for the glued stems. In addition, the results indicate that the bending strain in the upper part of the non-glued stem tended to reach the maximum value of bending strain immediately after the femur model section stood upright, whereas the bending strain in the upper and middle of the glued stem tended to reach the maximum value of bending strain immediately before the femur model section stood upright. Furthermore, when the non-glued and glued stems had the same value of bending strain, the average amplitude was smaller for the non-glued stem than for the glued stem by 2–3 dB.     

Characteristics of an actuator-driven pulsed water jet generator to dissecting soft tissue

This paper reports characteristics of an actuator-driven pulsed water jet generator applied, in particular, to dissect soft tissues. Results of experiments, by making use of high speed recording of optical visualization and varying nozzle diameter, actuator time interval, and their effects on dissection performance are presented. Jet penetration characteristics are compared with continuous water jet and hence potential assessment of pulsed water jets to clinical applications is performed.     

SUBPICOSECOND LASER PROCESSING OF POLYCRYSTALLINE SILICON MICROSTRUCTURES

Ultrashort-pulse lasers are able to recover stiction-failed microelectromechanical systems (MEMS) structures. A possible physical mechanism for this process is an electronic disruption of the bonding between the structure and the substrate, which depends strongly on the peak carrier temperatures. This article presents predicted carrier temperatures for polycrystalline silicon microcantilevers irradiated with ultrashort-pulse lasers. The effects of increased carrier-phonon coupling, reduced thermal conductivity, and increased absorption for polycrystalline silicon as compared to crystalline silicon are determined. An expression for the optimal absorption coefficient is derived for processes in which the excitation is desired at a specified depth into the material.     

Pt/TiN electrodes for stacked memory with polysilicon plug utilizing PZT films

Abstract

The mechanism of TiN barrier metal oxidation of Pt/TiN electrodes are investigated for planarized stacked memory utilizing lead zirconate titanate (PZT). Thinner (<100 nm) and highly oriented platinum films are required in gigabit scale ferroelectric nonvolatile memories whose capacitor size is comparable to PZT grain size. Oxygen diffusivity to oxidize TiN is found to depend on the Pt film thickness. In cross-sectional TEM images of PZT/Pt/TiN/Si, titanium oxide is observed beneath the Pt grain boundary. The oxygen is diffused through the Pt grain boundary under heat treatment in an oxygen atmosphere for crystallization of PZT films, and oxidizes the underlying TiN barrier metal.     

Randomized Controlled Trial of Darbepoetin α Versus Continuous Erythropoietin Receptor Activator Injected Subcutaneously Once Every Four Weeks in Patients with Chronic Kidney Disease at the Pre-Dialysis Stage

Continuous erythropoietin receptor activator (CERA) seems to maintain a stable hemoglobin (Hb) level because its half-life is longer than darbepoetin α (DA). Twenty chronic kidney disease (CKD) patients at the pre-dialysis stage who had been administered DA for over 24 weeks were randomly assigned to receive subcutaneous CERA or DA once every four weeks during 48 weeks. In both groups, the rate of achievement of target Hb level changed from 70% to 100% in weeks 0 to 48, with no significant difference between the groups. Compared with week 0, the Hb level was significantly increased from week 24 in the DA group and from week 8 in the CERA group. In addition, the reticulocyte count was significantly increased from week 4 in the CERA group compared with the DA group. There was no significant difference in the levels of estimated glomerular filtration rate and iron status between both groups. Because of the small number of patients in this study, only limited conclusions can be drawn. However, the results suggest that subcutaneous administration of DA or CERA once every four weeks to predialysis patients has similar effects on achievement of target Hb levels.