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991.
Di Pasqua AJ Huckle JE Kim JK Chung Y Wang AZ Jay M Lu X 《Small (Weinheim an der Bergstrasse, Germany)》2012,8(7):997-1000
Nanoparticles containing stable holmium ((165) Ho) are prepared by nanotemplate engineering and subsequently irradiated in a neutron flux to yield (166) Ho, a beta-emitting radiotherapeutic isotope. After intraperitoneal injection to mice bearing SKOV-3 ovarian tumors, significant tumor accumulation of the (166) Ho-nanoparticles is observed by SPECT imaging indicating the potential of these neutron activatable nanoparticles for internal radiation therapy of ovarian cancer metastases. 相似文献
992.
Ultrasound current source density imaging (UCSDI) potentially transforms conventional electrical mapping of excitable organs, such as the brain and heart. For this study, we demonstrate volume imaging of a time-varying current field by scanning a focused ultrasound beam and detecting the acoustoelectric (AE) interaction signal. A pair of electrodes produced an alternating current distribution in a special imaging chamber filled with a 0.9% NaCl solution. A pulsed 1 MHz ultrasound beam was scanned near the source and sink, while the AE signal was detected on remote recording electrodes, resulting in time-lapsed volume movies of the alternating current distribution. 相似文献
993.
W C Brumley Z Min J E Matusik J A Roach C J Barnes J A Sphon T Fazio 《Analytical chemistry》1983,55(8):1405-1409
994.
995.
Conclusions The proposed model of fatigue crack propagation based on the solution of the cyclic elastoplastic problem of the stress-strain state [1] makes it possible to take into account the effect of the triaxial stress state on the deformation of the material at the crack tip. The proposed algorithm of calculations of the state of damage on the basis of the principle of linear damage summation and also the agreement between the calculated and experimental data confirm the assumption on the controlling role of low-cycle damage in the mechanics of crack propagation in cyclic loading described from phenomenological positions. The main advantages of the proposed model are:The possibilities of calculating endurance in crack propagation or calculating the crack propagation rate for cases in which the variation of the range of the stress intensity factor along the crack length in structural members takes place at a variable loading asymmetry;the possibilities of describing the effect of loading asymmetry on the fatigue crack-propagation rate using only the strain criterion (Coffin's equation) since the range of the plastic strain intensity at the crack tip is, as shown in [1], a function of not only the range of the stress intensity factor K but also of its maximum value Kmax;the possibilities of describing the dependence of Kth on loading asymmetry based on the assumption on the constancy of the size of the structural element for the given material;the possibilities of describing the crack propagation rate in all the three sections of the dL/dN=f(K) diagram, starting with the values K similar to Kth and ending with the value of K at which monotonic quasistatic fracture becomes the controlling process.Translated from Problemy Prochnosti, No. 8, pp. 14–18, August, 1985. 相似文献
996.
A. N. Tynnyi Z. A. Bazilevich S. I. Mikitishin Ya. I. Lavrentovich G. V. Karpenko 《Materials Science》1972,5(3):242-244
Time-to-rupture and creep of polymethyl methacrylate (PMM) under the combined influence of stress, active liquid media, and -radiation were studied. It was shown that time-to-rupture of PMM under these conditions is determined mainly by the influence of the working medium when the absorbed radiation dose is less than about 10 Mrads and that -radiation increases the creep rate of PMM in active liquid media. 相似文献
997.
X. A. Chen;Y. E. Cheng;H. Xiao;G. Feng;Y. H. Deng;Z. L. Feng;L. Chen;X. M. Han;Y. J. Yang;Z. H. Dong;R. Zheng 《Radioprotection》2004,39(4):525-533
A twenty-year follow-up study was carried out at Baiyun Obo Rare-earth Iron Mine in China, This mine has been mined since 1958. Its ore contains 0.04% of ThO2 and 10% of SiO2. The purpose of this study is to investigate possible health effects in dust-exposed miners following long-term exposure to thorium-containing dusts and thoron progeny. By using the negative high voltage exhaled thoron progeny measurement system to estimate the miner’s thorium lung burden. The highest thorium lung burden among 1158 measurements of 638 miners was 11.11Bq. The incidence of stage 0+ pneumoconiosis was increased among dust-exposed miners. An epidemiological study showed that the lung cancer mortality of the dust-exposed miners was significantly (p < 0.005) higher than that of the non-exposed group. It is suggested that the difference results in the long-term exposure to thorium-containing dusts (carcinogens are ThO2 and SiO2) and thoron progeny. This is the first evidence in humans of the carcinogenicity after long-term inhalation of thorium-containing dusts and thoron progeny. The total person-years of observation for the dust-exposed miners and the controls were 62712 and 34672 respectively.https://doi.org/10.1051/radiopro:2004011 相似文献
998.
B. Wu;Z. Filipi;R. Prucka;D. Kramer;G. Ohl 《Oil & Gas Science and Technology》2007,62(4):539-553
Variable Valve Actuation (VVA) technology provides high potential for achieving improved performance, fuel economy and pollutant reduction. Benefits of VVA stem from better breathing and the ability to control internal residual. However, additional independent control variables in a VVA engine increase the complexity of the system, and achieving its full benefit depends critically on devising an optimum control strategy. The traditional approach relying on experimentation is in this case prohibitively costly, since the number of tests increases exponentially. Instead, this work formulates the task of defining actuator set-points as an optimization problem. It identifies simulation needs for supporting development of a generic methodology, capable of handling increased number of degrees of freedom. A high-fidelity tool predicts effects of various devices being considered. Since solving an optimization problem requires hundreds of function evaluations, direct use of the high-fidelity simulation leads to unacceptably long computational times. Instead, the Artificial Neural Networks (ANN) are trained with high-fidelity simulation results and used to represent engine s response to different control variable combinations with greatly reduced computational time. The paper describes a comprehensive simulation-based methodology, provides details of high-fidelity and surrogate modeling techniques, and then demonstrates application on a prototype four-cylinder spark-ignition engine with dual independent cam-phasers.https://doi.org/10.2516/ogst:2007047 相似文献
999.
A. M. Attia;D. Fratta;Z. Bassiouni 《Oil & Gas Science and Technology》2007,63(2):203-217
This paper presents the results of capillary pressure and electrical resistivity measurements for three kinds of core specimens: Berea sandstone, Quartz and Limestone. Experimental data of resistivity index, formation resistivity factor, tortuosity, capillary pressure, and water saturation exponent in the air/brine system for these cores are reported. The electrical resistivities data are evaluated using the modified Archie's law. Capillary pressure and electrical resistivity versus brine saturation results show the existence of two irreducible water saturations corresponding to two different physical phenomena. The two values of irreducible brine saturations yield upper and lower limits that can be used to estimate the production capacity of porous media. The detailed analysis of the data has also shown a change in the value of the saturation exponent. This change would be also be observed at the irreducible brine saturation as obtained with capillary pressure data.https://doi.org/10.2516/ogst:2007066 相似文献
1000.
采用两步沉淀对某黄金冶炼厂含高铜、铁氰化提金废水进行降铜除铁预处理后,对滤液分别进行A-21S树脂和201×7树脂吸附对比试验。结果表明,A-21S树脂对废水中各离子的吸附率均高于201×7树脂,对金和锌络合离子的吸附率高达96%以上。A-21S树脂吸附过程中,Au(CN)2-对CNT-、Cu(CN)32-和Zn(CN)42-的分离系数SA/B平均值分别为56.69、25和0.051,选择性系数KA/B平均值分别为56.69、487.63和1.015。A-21S树脂吸附Au(CN)2-的选择性比CNT-和Cu(CN)32-强,而吸附Au(CN)2-和Zn(CN)42-的亲和力接近。体系中Zn(CN)42-的存在对A-21S吸附Au(CN)2-有竞争。 相似文献