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61.
As the sensitivity of the new in vitro cancer detection techniques increases, a larger number of "false positive" results can be expected from control populations apparently free from malignant disease at the time of the test. An attempt is made to predict the number of unexplained positives, together with the expected age and sex distribution, using published cancer registration statistics. The predicted numbers are compared with the observed numbers of unexplained positives in two clinical trials of the MEM test. 相似文献
62.
Urinary amino acid excretion was determined in 31 leukemic patients and 29 normal individuals by rapid gas chromatographic analysis of 16 amino acids as their N-acetyl-n-propyl esters. The leukemic patients were concurrently undergoing, or had recently completed, chemotherapy. It was found that aspartic acid, threonine, and serine were of significance in distinguishing between patients "on" therapy and those "off" therapy. Patients with advanced disease have the greatest aminoaciduria, although both the normal and leukemic populations have wide individual ranges. Within both populations, men excrete a greater variety and quantity of amino acids than women. It is concluded that analysis of urinary amino acids represents a history of complex metabolic events, which is potentially useful for evaluating patient response to chemotherapy in leukemia. 相似文献
63.
For several months prior to birth a major portion of a family's attention, conversation, thought, and often worry, is directed toward the idea of a new child. This prolonged attention and anticipation contribute to making childbirth an emotionally charged experience. In psychological terms, it is therefore a critical period of peak motivation for learning, and a time to peak susceptibility to reinforcement. Theory, reason, and scientific evidence indicate thng with childbirth and early postpartum experiences, can significantly affect subsequent parental behaviors, the child's central environment influence. Evidence strongly suggests that these parental attitudes and behaviors so crucial to the child's ultimate well-being are learned rather than derived instinctually, and therefore they are malleable and can be taught, directed, and corrected. Through education and reinforcement it is possible to encourage parental behaviors and child interactions which are products of feelings of control, competence, accomplishment, understanding, and caring. Similarly we can recognize and work toward replacing attitudes, feelings, and behaviors that express fear, worry, and insecurity about the child. Over the past 50 years major changes have occurred in the practice of obstetrics and newborn pediatrics. Other major changes will necessarily occur as we move toward perinatal regionalization. Changes instigated solely on physiologic data can have unrecognized collateral effects on the psychological component of the childbirth experience. All concerned health care personnel, especially obstetricians and pediatricians, can insist that the importance of desirable mother-father-child interactions be recognized and that practices fostering them be afforded a high priority. I would like to endorse a comment from a recent article by Richmond concerning the advent of behavioral pediatrics by adding that behavioral obstetrics is also "an idea whose time has arrived". 相似文献
64.
Frictional anisotropy of oriented carbon nanotube surfaces 总被引:1,自引:0,他引:1
P.L. Dickrell S.B. Sinnott D.W. Hahn N.R. Raravikar L.S. Schadler P.M. Ajayan W.G. Sawyer 《Tribology Letters》2005,18(1):59-62
This report examines highly anisotropic tribological behavior of multi-walled nanotube films oriented in mutually orthogonal directions. The average values of coefficient of friction varied from extremely high values (=0.795) for vertically aligned nanotubes grown on rigid substrates to very low values (=0.090) for nanotubes dispersed flat on the same substrates. The results were insensitive to humidity, in contrast to graphite materials, and indicate that nanotubes could be utilized as both low and high frictional surfaces. 相似文献
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66.
L. S. Schadler L. C. Brinson W. G. Sawyer 《JOM Journal of the Minerals, Metals and Materials Society》2007,59(3):53-60
Polymer nanocomposites are polymer matrix composites in which the fillers are less than 100 nm in at least one dimension.
These composites have exhibited extraordinarily interesting properties. A defining feature of polymer nanocomposites is that
the small size of the fillers leads to a dramatic increase in interfacial area as compared to traditional composites. This
interfacial area creates a significant volume fraction of interfacial polymer with properties different from the bulk polymer
even at low loadings. The properties and structure of this interfacial region are not yet known quantitatively, presenting
a challenge both for controlling and predicting the properties of polymer nanocomposites. This paper provides a brief overview
of polymer nanocomposites with emphasis on the impact of the interfacial region. 相似文献
67.
Stephen W. Rothwell Evelyn Sawyer Jennifer Dorsey William S. Flournoy Timothy Settle David Simpson Gary Cadd Paul Janmey Charles White Kathleen A. Szabo 《Journal of materials science. Materials in medicine》2009,20(10):2155-2166
We investigated the inflammatory response in pigs exposed to salmon fibrinogen/thrombin dressings. Animals were exposed to
the material in 3 ways: (a) thrombin and fibrinogen were injected intravenously, (b) dual full-thickness skin lesions were
surgically created on the dorsal aspect of the swine and treated with the fibrinogen/thrombin bandage and a commercial bandage
or (c) a fibrinogen/thrombin bandage was inserted through an abdominal incision into the peritoneal cavity. Blood was collected
twice weekly and animals were sacrificed at 7, 10 or 28 days. Animals in the 28-day dermal lesion group were given an injection
of salmon fibrinogen/thrombin at the 10 day point to simulate a second bandage application. The immune response manifested
itself as induction of germinal centers in mesenteric lymph nodes and in the white pulp of the spleen. Examination of the
histology of the skin and organs showed a cellular inflammatory response with granulation tissue and signs of edema that resolved
by the 28-day stage. Antibodies reactive to salmon and human thrombin and fibrinogen were detected, but fibrinogen levels
and coagulation processes were not affected. In conclusion, animals treated with salmon fibrinogen/thrombin bandages demonstrated
a smooth recovery course in terms of both tissue healing and the immune response without adverse effects from the exposure
to the fish proteins. 相似文献
68.
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70.
Lubrication is critical for minimizing wear in mechanical systems that operate for extended time periods. Developing lubricants that can be used in engineering systems without replenishment – particularly those that are environmentally friendly – is very important for increasing the functional lifetime of mechanical components. In the present investigation, extended duration pin-on-disk experiments were carried out to determine the relative performance of a wide range of lubricant combinations in a commercial brake valve assembly. In the experiments, the lubricants were initially applied to the disk surface but were not replenished over a sliding distance of more than 6000 m. The experimental results revealed that the environmentally friendly lubricant boric acid was highly ineffective for reducing the wear in the surfaces tested. When combined with a commercial transmission fluid, however, the boric acid mixture proved to be highly effective in terms of both friction and wear performance. Based on the success of the combined lubricant experiments, the boric acid was then mixed with canola oil to form a completely natural lubricant combination. Based on further pin-on-disk experiments, this lubricant combination yielded the best wear performance of all the lubricants tested. The importance of these results, as related to the use of the natural lubricant combination in other engineering systems such as sheet metal stamping, was subsequently ascertained and discussed. 相似文献