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A Siddiqi JM Burrin K Noonan I James DF Wood CP Price JP Monson 《Canadian Metallurgical Quarterly》1997,82(3):753-759
Alterations of chromosome 8, including deletions of 8p, occur frequently in many tumors. In this study, fluorescence in situ hybridization was used to study the relationship between 8p deletions, 8q gains, and phenotype in bladder cancer. Cells from 87 tumors were examined by dual-labeling fluorescence in situ hybridization with a centromere 8 probe (pJM12) and P1 probes for 8p22, 8p12, 8q12, and 8q24. Both 8p22 deletions and 8q24 gains were strongly associated with tumor phenotype. There was a marked difference in 8p22 deletions between noninvasive (pTa) tumors (3/33) and minimally invasive (pT1) tumors (8/19; P = 0.005) whereas there was no significant difference between pT1 and muscle-invasive (pT2-4) tumors (19/35; P = 0.3926). Six tumors with 8p22 deletion were examined at 8p12. Three of these tumors showed no 8p12 deletion, narrowing down the site of a putative tumor suppressor gene distal to 8p12. In one other case, there was a marked increase in 8p12 copy number (> 40 per cell; amplification), suggesting the presence of an oncogene involved in bladder cancer at 8p12. The marked difference in 8p22 deletions between noninvasive (pTa) and minimally invasive (pT1) tumors is consistent with a role of a putative tumor suppressor gene on 8p for development of invasive tumor phenotype. 相似文献
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The elastic and adhesive properties of nominally vertically aligned carbon nanotube?(CNT) turfs have been measured using nanoindentation. The perceived stiffness of a CNT turf is dependent on the unloading rate, which decreases at slower unloading rates. Depth-controlled nanoindentation was used to examine adhesion effects. Adhesive loads between the turf and the probe tip increased as the time the tip is in contact with the turf increased. As these effects could be from either more tubes coming into contact with the tip due to relaxation and motion of CNTs relative to one another or each tube in contact increasing its adhesive behavior and sub-contact stiffness due to tube-tube interactions within the turf, electrical resistance measurements during nanoindentation were carried out. When the tip is held at a fixed nominal depth, the current remains constant while the contact load decreases, suggesting the number of tubes in contact with the tip stays constant with time while the relaxation mechanisms in the turf occur at positions lower than the contact surface. These observations, in conjunction with in situ TEM compression test of CNT arrays, are used to describe the relative effects the various length and time scales may have on the perceived properties measured during experiments, including elastic modulus and adhesion for gecko-like dry adhesives. 相似文献
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M. S. Kennedy D. F. Bahr N. R. Moody 《Metallurgical and Materials Transactions A》2007,38(13):2256-2262
The adhesion of metallic-ceramic interfaces is generally ascribed to the mixture of several mechanisms, including chemical
bonding, texture, strain transfer, and plasticity. This study examines the impact of alterations in chemical bonding along
an interface on the nanometer scale on the interfacial fracture energy. Using a well-characterized system of W/SiO2, small areas of the interface were masked with polymer tubes to prohibit the area from adhering well to the W film. This
showed that the interfacial fracture energy was proportional to the area of higher adhesion. This finding was then used to
study the growth of a Ti interlayer used for adhesion promotion in a Pt/SiO2 system. Because the adhesion energy slowly grew from values near the Pt/SiO2 to values typical of Ti/SiO2, the growth mechanism for DC magnetron sputtering of thin film Ti on SiO2 was inferred to be island growth instead of layer-by-layer growth.
This article is based on a presentation given in the symposium entitled “Deformation and Fracture from Nano to Macro: A Symposium
Honoring W.W. Gerberich’s 70th Birthday,” which occurred during the TMS Annual Meeting, March 12–16, 2006 in San Antonio,
Texas and was sponsored by the Mechanical Behavior of Materials and Nanomechanical Behavior Committees of TMS. 相似文献
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A 1-year-old boy presented with pericardial effusion, pulmonary infiltrates, and disseminated intravascular coagulation; lung biopsy indicated pulmonary lymphangiomatosis. He did not respond to medical therapy and was a poor surgical candidate; therefore, he underwent partial splenic embolization. The procedure resulted in a complete disappearance of the DIC and marked improvement in his cardiorespiratory status. He continues to thrive and is transfusion-independent 2 years after the procedure. 相似文献
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The COMPACT approach for defining structural criteria for substrates and inducers of cytochrome P450 (CYP) enzymes which mediate the formation of reactive intermediates is discussed in the context of prediction of potential carcinogenicity. This is broadened to encompass structural studies on mammalian P450s, including those relevant to genetic polymorphism in man. The use of the COMPACT system, in parallel with the structure alert program HazardExpert (now incorporated into the Pallas system), for evaluating human carcinogenicity data is reported, as an example of the possible employment of a battery of short-term test procedures for safety evaluation. In particular, the importance of using the log P value (as a measure of compound lipophilicity) to assess the likelihood of a potentially toxic compound reaching the site of activation, is emphasized by the finding that most procarcinogens requiring metabolic activation by P450s are lipophilic in nature. 相似文献