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排序方式: 共有208条查询结果,搜索用时 15 毫秒
191.
Tomohiko Nakagawa Takashi Kamei Liman Cong Yoh Hamada Narufumi Kitamura 《Science and Technology of Advanced Materials》2016,17(1):387-397
Contrast agents are often used to enhance the contrast of X-ray computed tomography (CT) imaging of tumors to improve diagnostic accuracy. However, because the iodine-based contrast agents currently used in hospitals are of low molecular weight, the agent is rapidly excreted from the kidney or moves to extravascular tissues through the capillary vessels, depending on its concentration gradient. This leads to nonspecific enhancement of contrast images for tissues. Here, we created gold (Au) nanoparticles as a new contrast agent to specifically image tumors with CT using an enhanced permeability and retention (EPR) effect. Au has a higher X-ray absorption coefficient than does iodine. Au nanoparticles were supported with polyethylene glycol (PEG) chains on their surface to increase the blood retention and were conjugated with a cancer-specific antibody via terminal PEG chains. The developed Au nanoparticles were injected into tumor-bearing mice, and the distribution of Au was examined with CT imaging, transmission electron microscopy, and elemental analysis using inductively coupled plasma optical emission spectrometry. The results show that specific localization of the developed Au nanoparticles in the tumor is affected by a slight difference in particle size and enhanced by the conjugation of a specific antibody against the tumor. 相似文献
192.
Laboratory and Field Evaluations of Recycled Gypsum as a Stabilizer Agent in Embankment Construction
Approximately 1.6 million tons of gypsum waste plasterboard are produced annually in Japan. As such, it is essential to find an alternative way to reduce the quantities of this waste material to avoid environmental problems and the high cost of disposal in landfill. This paper describes a case study focused on the use of recycled gypsum, which is derived from gypsum waste plasterboard, to improve the strength of soft clay soil for embankment construction projects taken in consideration environmental impacts. Four different recycled gypsum contents ranging from 0 to 10% was investigated. Two different types of cements—Portland and Furnace slag type B—with a content ranging from 0 to 3% was used to develop solidification for recycled gypsum and improve environmental properties. For this purpose, a series of unconfined compression tests were conducted to evaluate strength performance of treated clay. While a series of environmental tests were conducted to explore the solubility concentration of fluorine, boron, and hexavalent chromium in the untreated and treated soil specimens. Furthermore, hydrogen sulfide and pH were investigated. Results showed that compressive strength and unit weight of treated clay soil increased with the increase of recycled gypsum content. The strength obtained in the field for treated soil with recycled gypsum was found to be greater than that obtained in the laboratory. The early curing days for soil-gypsum mixture had a significant effect on strength performance compared to the later days. The additives of recycled gypsum for tested soil swiftly increased the strength. This is a vital property for improvement embankment trafficability that helps to reduce the construction time and cost. The use of recycled gypsum within the investigated limits had no adverse effect on pH value and hydrogen sulfide gas was found to be less than the standard permitted limits. As well, the solubility concentrations for fluorine, boron, and hexavalent chromium were found within the permitted standard limits in Japan. The curing time had a significant effect on the reduction the release of harmful substance elements investigated. Furnace cement type B had the potential to improve the mechanical and environmental functions for soil-gypsum mixture. It is recommended that Furnace cement type B be used as a solidification agent for soil treated with recycled gypsum because it has low cost and it is more environmentally friendly than Portland cement. 相似文献
193.
The role of intracellular calcium in the modifications of naloxone-precipitated withdrawal jumping in morphine-dependent mice by diabetes was examined. Naloxone-precipitated withdrawal jumping was significantly less in morphine-dependent diabetic mice than in morphine-dependent non-diabetic mice. Intracerebroventricular (i.c.v. ) pretreatment with ryanodine attenuated naloxone-precipitated withdrawal jumping in morphine-dependent non-diabetic mice. However, naloxone-precipitated withdrawal jumping in morphine-dependent diabetic mice was not affected by i.c.v. pretreatment with ryanodine. Moreover, i.c.v. pretreatment with thapsigargin, a Ca2+-ATPase inhibitor, enhanced naloxone-precipitated withdrawal jumping in morphine-dependent non-diabetic mice, but not in morphine-dependent diabetic mice. The noradrenaline (NA) turnover in the frontal cortex in morphine-dependent non-diabetic mice, but not in morphine-dependent diabetic mice, was significantly increased by naloxone injection. Naloxone-induced enhancement of NA turnover in morphine-dependent non-diabetic mice, but not in morphine-dependent diabetic mice, was blocked by i.c.v. pretreatment with ryanodine. In contrast to ryanodine, thapsigargin enhanced naloxone-induced enhancement of NA turnover in morphine-dependent non-diabetic mice. These results suggest that increased intracellular calcium augmented naloxone-precipitated withdrawal jumping and the turnover rate of NA in the frontal cortex in morphine-dependent non-diabetic mice. Furthermore, it seems likely that the attenuation of naloxone-precipitated withdrawal jumping in morphine-dependent diabetic mice may be due, in part, to the dysfunction of intracellular calcium store. 相似文献
194.
Kakugawa H. Kamei S. Masuzawa T. 《Parallel and Distributed Systems, IEEE Transactions on》2008,19(9):1153-1166
The group mutual exclusion problem is a generalization of mutual exclusion problem such that a set of processes in the same group can enter critical section simultaneously. In this paper, we propose a distributed algorithm for the group mutual exclusion problem in asynchronous message passing distributed systems. Our algorithm is based on tokens, and a process that obtains a token can enter critical section. For reducing message complexity, it uses coterie as a communication structure when a process sends a request messages. Informally, coterie is a set of quorums, each of which is a subset of the process set, and any two quorums share at least one process. The message complexity of our algorithm is $O(|Q|)$ in the worst case, where $|Q|$ is a quorum size that the algorithm adopts. Performance of the proposed algorithm is presented by analysis and discrete event simulation. Especially, the proposed algorithm achieves high concurrency, which is a performance measure for the number of processes that can be in critical section simultaneously. 相似文献
195.
Noguchi K. Okada A. Kamei S. Suzuki S. Matsuoka M. 《Lightwave Technology, Journal of》2005,23(4):1568-1575
AWG-STAR is a star-shaped network that utilizes a uniform-loss cyclic frequency arrayed-waveguide grating (AWG) as a wavelength router to obtain full-mesh interconnection between surrounding wavelength-division-multiplexing nodes. In this paper, we describe a temperature control-free AWG-STAR network that employs a coarse wavelength-division-multiplexing AWG-router. The center wavelength and transmission band of the AWG-router are designed based on the light source wavelength shift that results from changes in operating temperature. The system employs bidirectional transmission to avoid coherent crosstalk from adjacent channels. A cost-effective and small-scale full-mesh network is realized for metropolitan areas. 相似文献
196.
Yoshiyuki Kojima Shinnosuke Kamei Nobuyuki Nishimiya 《Materials Research Bulletin》2010,45(2):121-136
This paper describes the energy efficient synthesis of a red-emitting Eu3+-activated amorphous calcium silicate phosphor produced by heating a Eu3+-activated calcium silicate hydrate phosphor. Concentration quenching of the Eu3+-activated calcium silicate hydrate phosphor was not observed and the emission intensity did not decrease up to a Eu/(Ca+Eu) atomic ratio of 0.46. Heating of the Eu3+-activated calcium silicate hydrate (Eu/(Ca+Eu) atomic ratio = 0.32) phosphor produced an amorphous Eu3+-activated calcium silicate phosphor, which had a maximum emission intensity at 870 °C and emitted in the red under near-ultraviolet irradiation (395 nm). The emission intensity of the Eu3+-activated amorphous calcium silicate phosphor was about half that of a commercial BaMgAl10O17:Eu2+ phosphor, and shows great potential for application in white light-emitting diodes. 相似文献
197.
This study examines the wetting–drying durability of soft clay soil stabilized with recycled Bassanite, produced from gypsum waste. Specifically, this study focuses on an investigation of the effects of the moisture conditions on the strength performance and durability of very soft clay soil stabilized with Bassanite and furnace cement mixtures during the wetting–drying cycles, referred to as weathering conditions in this study. Cylindrical stabilized soil specimens were produced and then cured for 28 days. The cured specimens were subjected to different numbers of wetting–drying cycles, and then tested for unconfined compressive strength. The results show that the compressive strength increased with an increase in the Bassanite content for the different wetting–drying cycles investigated. The increase in the Bassanite content is associated with the increase in the dry unit weight, as well as in the decrease in the moisture content of the stabilized specimens for the different wetting–drying cycles investigated. The compressive strength of the soil stabilized with the Bassanite and furnace cement mixtures gradually decreases with an increase in the number of wetting–drying cycles, and the earlier cycles are seen to have a more negative effect on durability than the later cycles. Generally, the influence of the wetting–drying cycles on changes in the strength, durability and volume of the soft clay soil stabilized with Bassanite and furnace cement mixtures is not significant. This is evidence that the use of recycled Bassanite, produced from gypsum waste to stabilize soft clay soil, achieves acceptable durability, raises the strength performance and improves the engineering properties of soft clay soil in a wet environment. In addition, the effective use of gypsum waste contributes to the development of a sustainable society by reducing the huge quantity of solid waste and establishing a sound environment. 相似文献
198.
Lightweight soil technology has been widely used in construction projects to solve soft ground problems. Previous work, however, has shown that the maximum interior temperature of field test bodies reaches to about 90°C. On the other hand, industrial waste disposal is an increasing problem. PET (polyethylene terephthalate) waste is now generated in vast quantities to increased consumption of drinking water sold in PET bottles. Making effective use of PET waste as a ground material may help solve the problem of its disposal. This paper describes the effects of initial high temperature curing on unconfined compressive strength and the microstructure of foamed mixture lightweight soil containing PET flake. Increase in PET-cement ratio lessened the decrease in unconfined compressive strength with increasing initial temperature. This property makes PET flake useful as a construction material. However, unconfined compressive strength decreases with increasing initial temperature at all PET-cement ratios. Observations show that the microstructure of foamed mixture lightweight soil containing PET flake have noticeable cracks if samples are cured at 90°C for 1 day; the PET flake is not completely combined with the matrix. The formation of this microstructure is the main factor of the remarkable strength decrease based on initial high temperature curing. 相似文献
199.
Hui Zhou Parasuraman Selvam Keiji Hirao Ai Suzuki Daisuke Kamei Seiichi Takami Momoji Kubo Akira Imamura Akira Miyamoto 《Tribology Letters》2003,15(2):155-162
The dynamics of the degradation process of a monoester (ethyl acetate) at reaction temperatures was clarified for the first time by a novel tight-binding, quantum-chemical, molecular-dynamics method with initial parameters that are determined completely on the basis of first-principles calculations. It was confirmed that the proposed method can calculate the structure, electronic states and total energy of a monoester and its fragments as accurately as the density-functional calculations, while the CPU time of the new method is over 5000 times faster than that of the density-functional calculations. In the case of the acetic ester molecule, the -hydrogen which is located at the ethanol group was cleaved quickly. Compared to it, -hydrogen was cleaved more slowly than -hydrogen. Each atom expressed cleavage and association with repetition. As a whole, degradation phenomena were observed in this simulation. This observation agrees with experimental data. 相似文献
200.
Y Sugimoto Y Nakayama H Kishida T Hayakawa R Fujiwara C Kamei 《Canadian Metallurgical Quarterly》1997,19(8):547-552
The phase S ratio in cell cycles were analyzed in livers with hyperplastic foci (HPF) and in livers without HPF by nuclear DNA determinations using flow cytometry, and by staining with argyrophilic proteins of the nucleolar organizer region (AgNOR). Flow cytometric analysis was done on 50 fresh frozen specimens of livers resected from 50 patients with hepatocellular carcinoma (HCC). Paraffin sections from the same patients were analyzed using AgNOR staining. There were 25 cases each with and without HPF. We examined the stage of fibrosis and the grade of inflammatory activity according to the modified Scheuer and Desmet scale. The incidence of HCC recurrence among these patients was also studied. The average phase S ratio of the livers of the patients with HPF was 6.5 +/- 3.2%, and that of the livers of the patients without HPF was 4.0 +/- 2.5%. The ratio differed significantly between the two groups (P < 0.01). The average AgNOR score for HPF lesions of the HPF-positive cases was 1.60 +/- 0.34, that for non-HPF lesions in the HPF-positive cases was 1.29 +/- 0.12, and that for the HPF-negative cases was 1.19 +/- 0.14. Significant differences were found between the average AgNOR scores for HPF lesions of the HPF-positive cases and the non-HPF lesions of the HPF-positive cases (P < 0.01), as well as between the non-HPF lesions in the HPF-positive cases and the HPF-negative cases (P < 0.05). Severe fibrosis (stage 3) and cirrhosis (stage 4) were found in 76% of HPF-positive cases and 48% of HPF-negative cases. The livers of HPF-positive patients were significantly more cirrhotic than those of HPF-negative patients (P < 0.05). The association between HPF and the inflammatory grade was not significant (P > 0.05). The incidence of HCC recurrence among HPF-positive cases was significantly higher than that among the HPF-negative cases (P < 0.05). The average phase S ratio of the recurrent HPF-positive patients was 7.48 +/- 3.48%, significantly higher than that of HPF negative cases (5.57 +/- 3.06%, P < 0.05). Hyperplastic foci of the liver was shown to be a highly proliferative lesion. The proliferative activity of the non-HPF lesions in the HPF-positive patients was also higher than that of the HPF-negative patients. Hyperplastic foci tended to be present in cirrhotic livers, but it was not associated with the grade of inflammatory activity of the liver. Hyperplastic foci may represent an important predictor of recurrence after hepatic resection. 相似文献