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31.
Electron beam sterilization of cyclo olefin polymer leads to polymer degradation and production of alkyl radicals
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Hideaki Kiminami Yasufumi Imae Eiji Takahashi Hong Wei Satoshi Oomura Yoshihiko Abe 《应用聚合物科学杂志》2016,133(23)
We investigated the effects of electron‐beam (EB) sterilization on syringe barrels manufactured from cyclo olefin polymer (COP). The chemical structure of the polymer was determined by interpreting the 13C NMR and DEPT‐135 spectra of the COP resin. The antioxidants in the resin were identified by analyzing the liquid chromatography‐photo diode array‐mass spectrometry (LC‐PDA‐MS) data for the methanol extract of the resin and the gas chromatography‐mass spectrometry (GC‐MS) data for the supercritical methanol degradation products of the extract. NMR and LC‐PDA‐MS analyses revealed that EB sterilization produces degradation products in the COP main chain and reduces the quantity of the antioxidants in the COP resin. ESR spectra of the EB‐sterilized syringe barrels indicated the presence and location of alkyl radicals, which were generated in the COP main chain by EB sterilization. ESR analyses also indicated that the quantity of alkyl radicals decreased over time. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43498. 相似文献
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33.
Yoshihiko Okada Kaori Sasaki Baiqian Zhong Hideki Ishida Takeshi Mitsuda 《Journal of the American Ceramic Society》1994,77(5):1319-1323
A mixture of CaO and silicic acid prepared with a Ca/Si ratio of 2.0 was hydrothermally synthesized at 80° to 200°C, and the thermal decomposition behavior of the products (C-S-H with Ca(OH)2 ) was analyzed using XRD, 29 Si MAS NMR, and the trimethylsililation method (TMS). It was found that the main silicate anion structure of C-S-H was a mixture of a dimer and a single-chain polymer (larger than Si5 O16 ) and that polymerization advanced with an increase of the synthesizing temperature. On heating, the products decomposed to form β-C2 S. It was found that the decomposition was gradual and that the-higher the temperature of hydrothermal synthesis, the lower was the temperature of the decomposition into β-C2 S. Although the decomposition proceeded to form a monomer (β-C2 S) from the polymer and dimer, this dimer was resistant to heat and did not decompose unless heated to above 400°C. 相似文献
34.
Nanospheres of poly(lactide-co-glycolide) (PLGA), a biodegradable polymer, have been prepared using the conventional solvent diffusion method. In this study,
a method combining the solvent diffusion method and a two-step (premix) membrane emulsification technique is proposed for
the preparation of monodisperse PLGA nanospheres with a diameter of 200 nm. The monodispersity of the PLGA nanospheres was
higher than that of nanospheres obtained by the conventional solvent diffusion method. Generally, preparation of small particles
or droplets by the membrane emulsification technique requires a supply of high-pressure nitrogen gas to force the emulsion
or dispersion solution through the small pores of the membrane. However, in the technique proposed here, low-pressure nitrogen
gas (0.02–0.11 kgf/cm2) is sufficient. Thus, using this technique, one can obtain monodisperse PLGA nanospheres with a diameter of 200 nm in a relatively
short period of time under low-pressure nitrogen gas. 相似文献
35.
The authors developed a two-dimensional one-temperature chemical non-equilibrium (1T-NCE) model of Ar-CO2-H2 inductively coupled thermal plasmas (ICTP) to investigate the effect of pressure variation. The basic concept of one-temperature model is the assumption and treatment of the same energy conservation equation for electrons and heavy particles. The energy conservation equations consider reaction heat effects and energy transfer among the species produced as well as enthalpy flow resulting from diffusion. Assuming twenty two (22) different particles in this model and by solving mass conservation equations for each particle, considering diffusion, convection and net production terms resulting from hundred and ninety eight (198) chemical reactions, chemical non-equilibrium effects were taken into account. Transport and thermodynamic properties of Ar-CO2-H2 thermal plasmas were self-consistently calculated using the first-order approximation of the Chapman-Enskog method. Finally results obtained at atmospheric pressure (760 Torr) and at reduced pressure (500, 300 Torr) were compared with results from one-temperature chemical equilibrium (1T-CE) model. And of course, this comparison supported discussion of chemical non-equilibrium effects in the inductively coupled thermal plasmas (ICTP). 相似文献
36.
This paper describes the classification of various human actions from brain activity. In particular, we focus on grasping movements and estimate grasping patterns from electroencephalogram (EEG) data. EEG data is converted to grasping features by using a common spatial pattern filter (CSP filter), and the features are subsequently classified into grasping categories by using the k-nearest neighbor method. We tested the pipeline of feature extraction and classification on the EEG dataset. The EEG data were acquired while participants grasped an object according to the Cutkosky’s grasping taxonomy, in which grasping movements are categorized into nine power-type grasping patterns and seven precision-type grasping patterns. The best classification rate for 9-class power-type grasping patterns was 48% and for 7-class precision-type grasping patterns was 40%. 相似文献
37.
Yoshihiko Hibi Katsuyuki Fujinawa Seiji Nishizaki Kazuo Okamura Masaharu Tasaki 《Soils and Foundations》2010,50(1):143-159
Diffusion, dispersion, and advection are important processes in multi-gas systems in soils. To date, both Fick's model and the Dusty Gas (DG) model have been used to model the movement of gases in these systems. Dispersion is included in the dispersion-advection equation with Fick's Model for the movement of gases in gas-phase of soil, yet the movement of gases in multi-component gas-soil systems is considered to be expressed more accurately by the DG model than by Fick's model. However to date, no study has investigated the necessity of considering dispersion in the Dusty Gas (DG) model. We carried out column experiments for nitrogen-methane, nitrogen-carbon dioxide, and carbon dioxide-methane binary gas systems in sandy soil, and also did simulations on the same systems using both Fick's model and the DG model. A comparison of the results of the column experiments with our simulations confirmed that there was no need to consider the dispersion in the advection-diffusion equations with the DG model when the velocity of gas was 0.05-0.4 cm/s in Toyoura sand. Furthermore, our experiments and simulations with the DG model showed that, rather than dispersion, tortuosity should be taken into account in application of the DG model to the above condition. 相似文献
38.
Muhammad Aamer Rafique Bhutta Yoshihiko Ohama Ken Tsuruta 《Construction and Building Materials》2011,25(2):779-784
The present study examines the applicability of polymer mortar panels using a methyl methacrylate (MMA) solution of waste expanded polystyrene (EPS) to develop effective recycling processes for the EPS, referring to the strength properties of a polymer-impregnated mortar panel with almost the same performance as commercial products. An MMA solution of EPS is prepared by dissolving EPS in MMA, and unreinforced and steel fiber-reinforced polymer mortars are mixed using the EPS-MMA-based solution as a liquid resin or binder. Polymer mortar panels (PMPs) using the EPS-MMA-based polymer mortars without and with steel fiber and crimped wire cloth reinforcements and steel fiber-reinforced polymer-impregnated mortar panel (PIMP) are prepared on trial, and tested for flexural behavior under four-point loading. The EPS-MMA-based PMPs are more ductile than the PIMP, and have a high load-bearing capacity. Consequently, they can replace PIMP in practical applications. 相似文献
39.
Yoshihiko Yokoyama D. Gary Harlow Peter K. Liaw Akihisa Inoue 《Metallurgical and Materials Transactions A》2010,41(7):1780-1786
High fatigue strength is one of the important factors that facilitates the industrial usage of bulk metallic glasses (BMGs).
Fatigue data were analyzed using the Weibull probability models for BMGs produced with different casting processes in order
to study the reliability of fatigue strengths of cast glassy alloys. The fatigue data of tilt-cast and high-pressure-cast
BMGs can be explained by a three-parameter Weibull cumulative distribution function (cdf) and a mixture model of two-parameter
Weibull cdfs, respectively. We conclude that the cast defects, which reduce fatigue strength, should be eliminated in order
to realize a high reliability of fatigue strengths. 相似文献
40.