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排序方式: 共有678条查询结果,搜索用时 31 毫秒
81.
Parab HJ Huang JH Lai TC Jan YH Liu RS Wang JL Hsiao M Chen CH Hwu YK Tsai DP Chuang SY Pang JH 《Nanotechnology》2011,22(39):395706
The feasibility of using gold nanoparticles (AuNPs) for biomedical applications has led to considerable interest in the development of novel synthetic protocols and surface modification strategies for AuNPs to produce biocompatible molecular probes. This investigation is, to our knowledge, the first to elucidate the synthesis and characterization of sodium hexametaphosphate (HMP)-stabilized gold nanoparticles (Au-HMP) in an aqueous medium. The role of HMP, a food additive, as a polymeric stabilizing and protecting agent for AuNPs is elucidated. The surface modification of Au-HMP nanoparticles was carried out using polyethylene glycol and transferrin to produce molecular probes for possible clinical applications. In vitro cell viability studies performed using as-synthesized Au-HMP nanoparticles and their surface-modified counterparts reveal the biocompatibility of the nanoparticles. The transferrin-conjugated nanoparticles have significantly higher cellular uptake in J5 cells (liver cancer cells) than control cells (oral mucosa fibroblast cells), as determined by inductively coupled plasma mass spectrometry. This study demonstrates the possibility of using an inexpensive and non-toxic food additive, HMP, as a stabilizer in the large-scale generation of biocompatible and monodispersed AuNPs, which may have future diagnostic and therapeutic applications. 相似文献
82.
As networks grow in size and complexity, both the probability and the impact of failures increase. The pre-allocated backup
bandwidth cannot provide 100% protection guarantee when multiple failures occur in a network. In this article, we focus on
how to recover the protecting capabilities of FIPP (Failure-independent path-protecting) p-cycles against the subsequent links
failure on WDM networks, after recovering the working paths affected by the failure of link. Two recovering policies are designed
to recover the protecting capabilities of the FIPP p-cycles if possible, unless there is no sufficient network resource. They
are Cycle Recovery Policy and Path Recovery Policy. In addition, a Cycle Adjust algorithm is proposed and used to recover the affected cycles. The simulation results of the proposed methods are also given. 相似文献
83.
Yuan Hsing Fu Ai Qun Liu Wei Ming Zhu Xu Ming Zhang Din Ping Tsai Jing Bo Zhang Ting Mei Ji Fang Tao Hong Chen Guo Xin Hai Zhang Jing Hua Teng Nikolay I. Zheludev Guo Qiang Lo Dim Lee Kwong 《Advanced functional materials》2011,21(18):3589-3594
A micromachined reconfigurable metamaterial is presented, whose unit cell consists of a pair of asymmetric split‐ring resonators (ASRRs); one is fixed to the substrate while the other is patterned on a movable frame. The reconfigurable metamaterial and the supporting structures (e.g., microactuators, anchors, supporting frames, etc.) are fabricated on a silicon‐on‐insulator wafer using deep reactive‐ion etching (DRIE). By adjusting the distance between the two ASRRs, the strength of dipole–dipole coupling can be tuned continuously using the micromachined actuators and this enables tailoring of the electromagnetic response. The reconfiguration of unit cells endows the micromachined reconfigurable metamaterials with unique merits such as electromagnetic response under normal incidence and wide tuning of resonant frequency (measured as 31% and 22% for transverse electric polarization and transverse magnetic polarization, respectively). The reconfiguration could also allow switching between the polarization‐dependent and polarization‐independent states. With these features, the micromachined reconfigurable metamaterials may find potential applications in transformation optics devices, sensors, intelligent detectors, tunable frequency‐selective surfaces, and spectral filters. 相似文献
84.
Heat transfer enhancement by metal screens and metal spheres in phase change energy storage systems 总被引:1,自引:0,他引:1
Hisham M. Ettouney Imad Alatiqi Mohammad Al-Sahali Safaa Ahmad Al-Ali 《Renewable Energy》2004,29(6):841-860
This study focuses on heat transfer enhancement in double pipe energy storage system. Enhancement is achieved by use of metal screens/spheres placed inside the phase change material (PCM), which is paraffin wax and results in increasing the effective thermal conductivity of the combined media of PCM and metal screens/spheres. The experiments are conducted as a function of the diameter and number of spheres inserted in the phase change material. Also, the experiments investigate the effect of increasing the temperature of the heat transfer fluid (HTF). Results are presented in terms of variations in the PCM Nusselt number and the melting Fourier number. Results indicate three-fold decrease in the Fourier number and similar increase in the Nusselt number. Replacing 2-volume percentage of the wax material by the metal spheres results in this large enhancement. 相似文献
85.
Din KS 《The Science of the total environment》2011,409(24):5301-5304
The concentration of 210Po was determined in different foodstuffs of plant origin purchased from markets in Qena City, Upper Egypt. Measurement of 210Po has been carried out using alpha spectrometry technique in different food categories such as vegetables, fruits, cereals beverages and herbs. The general range of 210Po activity levels ranged widely from < 0.010-18.6 ± 0.910 mBq g− 1, with minimum being in cereal samples and maximum being in beverage samples. Tea samples recorded highest activity concentrations of 210Po with lowest value of 10 ± 0.54 mBq g−1 for Crown tea and highest value of 18.6 ± 0.910 mBq g−1 for El maabad tea. The daily intake of 210Po from food consumption reveals that vegetables are the biggest contributors, while beverages are the lowest. The effective ingestion dose has been estimated for Qena City residents and it was found in the range 0.008-38.3 μSv y−1. 相似文献
86.
Z. G. Ter-Martirosyan Din’ Kwang Nam Nguen Zang Nam 《Soil Mechanics and Foundation Engineering》2007,44(2):39-47
Problems of interaction between a single long pile (more than 20 m) or a group of long piles as component parts of a pile
foundation and soil are discussed on the basis of a new geomechanical model. The settlement of a pile or group of piles is
caused primarily by shear deformations of a soil mass of limited area and depth, and also as a result of deformations of the
mass beneath the lower ends of the piles.
__________
Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 2, pp. 2–7, March–April, 2007. 相似文献
87.
Bio-film formation on type 254 SMO stainless steel in Arabian Gulfwater was followed by measuring the variation of the open circuit potentials of test coupons under a variety of conditions. The time-potential curves exhibited two plateaus corresponding to oxide thickening and later to bio film development. The rate of film formation was found to depend on the ambient seawater temperature, which varied with the season. The reduction of the biological activity of the water through additions of pre-boiled and cooled seawater resulted in the retardation of bio-film formation and in the shift of the final steady-state potential towards less positive values. Similar behaviour was obtained when concentrating seawater by the addition of solid salt. The simultaneous reduction of biological activity and of salt content resulted. The characteristics ofthe formed bio-film depend on the nature ofthe metal surfaces. Smooth surfaces allowed the development of thin clear films while thicker dark films formed on coarse rough surfaces. These were usually associated with the growth of worm-like structures, initiating crevice and pitting corrosion. 相似文献
88.
Summary Polymer-supported ammonium salts of methyl and ethyl xanthates react with alkyl halides to yield S-dithiocarbonates. 相似文献
89.
KE el Din MJ de Wildt PF Rosier H Wijkstra FM Debruyne JJ de la Rosette 《Canadian Metallurgical Quarterly》1996,155(3):1018-1022
PURPOSE: We evaluated the urethrocystoscopic findings and results of urodynamic studies in elderly men with voiding complaints. MATERIALS AND METHODS: A total of 492 consecutive patients with voiding complaints underwent a standardized screening program, including transrectal ultrasonography of the prostate, urodynamic investigations with pressure-flow study analysis and flexible urethrocystoscopy. RESULTS: A significant correlation was found between bladder trabeculation and grade of bladder outlet obstruction. Detrusor instability correlated significantly with grade of trabeculation. Grade of obstruction showed a clear correlation with prostatic occlusion of the urethra and the presence of a middle lobe at cystoscopy. CONCLUSIONS: The findings at urethrocystoscopy correlate well with those of urodynamic investigations. 相似文献
90.
The dissolution of Fe, cu, Zn and Al in nitric, hydrochlorid and sulfuric acids is retarded by low concentrations of thiourea, while higher thiourea concentrations may bring about a stimulation of corrosion. In nitric acid thiourea is probably oxidised (heat evolution); the dithioformamidine formed at first is then hydrolysed to give diaminocarbonyl disulfide which again is reduced to thiocarbamic acid at the cathodic sites of the surface. The depolarisation thus produced gives rise to accelerated dissolution. In non-oxidising acids a monomolecular layer of thiourea is adsorbed at the metal at first; its subsequent reduction to sulfide and hydrogen sulfide again gives rise to an enhancement of corrosion. The critical concentration of the transition from inhibition to stimulation depends ont he type of the acid and its concentration. 相似文献