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71.
Filament winding is a process in which tensioned resio-impregnated continuous fibers are placed on specified paths of a rotating mandrel to cover the entire surface thus forming a composite component. Traditionally, filament winding is carried out on multi-saris numerically controlled lathe-like machines. This paper describes the evaluation of a robot based filament winding cell consisting of an industrial robot (ASEA IRB 6/2) and an in-house fabricated mandrel drive mechanism, both being coordinated by a personal computer. As in many manufacturing processes, tradeoffs exist between accuracy and speed. The accuracy vs speed relationships of the robotic winding cell were experimentally determined for discrete, fine and medium movement modes while traversing a segmented delivery eye path for a cylindrical mandrel in three configurations (in-line, offset and angled with respect to the axis of rotation). The results show that the robot winding cell is appropriate for very accurate winding of fiber strands if the mandrel axis is concentric with the mandrel drive axis and the discrete mode (i.e. low speed) of the robot is used. For high speed wet winding all three configurations can be accurately wound in the discrete and fine modes. 相似文献
72.
73.
A study was undertaken to determine the susceptibility or resistance of 9 outbred experimental or commercial poultry lines to Salmonella enteritidis PT4. Young chicks were inoculated either intramuscularly or orally just after hatching. After intramuscular challenge the lines could be divided into susceptible lines (LD 50% < or = 10(2) Salmonella per animal), intermediate lines (LD 50% about 10(4) Salmonella) and resistant lines (LD 50% > 10(5) Salmonella). The results obtained after oral challenge confirmed these 3 groups for both mortality rates and the probability of the presence of salmonellae in the spleen and liver. There was no difference between lines concerning caecal carriage. 相似文献
74.
Surface-enhanced resonance Raman scattering (SERRS) of substrate-free and substrate-bound forms of the P450 domain of cytochrome P450 BM3 are reported and assigned. Substrate-free P450 yields mixed spin heme species in which the pentacoordinate high-spin arrangement is dominant. The addition of laurate or palmitate leads to an increase in high spin content and to an allosteric activation of heme mode v29, which is sensitive to peripheral heme/protein interactions. Differences between laurate and palmitate binding are observed in the relative intensities of a number of bands and the splitting of the heme vinyl modes. Laurate binding to P450 results in different protein environments being experienced by each vinyl mode, whereas palmitate binding produces a smaller difference. The results demonstrate the ability of SERRS to probe substrate/prosthetic group interactions within an active site, at low protein concentrations. 相似文献
75.
Private health services have expanded in many developing countries over the last 10 yr. Qualified private practitioners provide basic health care for poorer groups in urban areas, although health care planners frequently criticize them for providing poor quality of care, charging high fees and failing to provide preventive health advice. In Karachi, a large city with more than 400 slums, private practitioners are important providers of care to the poor. This study assessed the nature and quality of care provided by 201 practitioners selected from four districts of the city. Vignettes of specific medical problems were used to assess their knowledge and their practice was measured by observing 658 doctor-patient contacts. The results show that knowledge was closer to accepted medical management than was their actual prescribing practice. On the other hand, their manners and interpersonal behaviour were good. Thus poor prescribing practice, which might equally stem from market influences as lack of knowledge, is the cause of low standards of care. In these circumstances, didactic in-service training to improve prescribing practice is unlikely to be successful. 相似文献
76.
Five cyanotic newborn infants underwent cardiac catheterization between 8 and 36 hours of age with a tentative diagnosis of cyanotic congenital heart disease. All had normal cardiovascular anatomy. Cyanosis was the result of persistence of fetal cardiopulmonary circulation with right-to-left shunting across the ductus arteriosus. In all infants, cyanosis resolved spontaneously and the infants survived without sequelae. Admission chest roentgenograms of all infants showed marked hyperinflation of the lungs. Except for severe hypoxemia, the clinical presentation, chest films, and course of illness of these infants were consistent with transient tachypnea of the newborn. It is proposed that an increase in pulmonary vascular resistance, due to hyperinflation of the lungs, was the mechanism which reopened the fetal cardiopulmonary circulatory channels and produced hypoxemia, and that these infants suffered from a rare manifestation of a usually benign newborn respiratory condition. Further, given these pathophysiologic mechanisms, the use of continuous transpulmonary pressure gradients in the management of such infants would be contraindicated. 相似文献
77.
Leucocyte-migration inhibition was to determine the state of hypersensitivity in 65 diabetic patients with different stages of retinopathy and 21 nondiabetic controls. About one third of the patients with simple or proliferative retinopathy exhibited significant leucocyte-migration inhibition of 0.2 mg/ml. protein concentration of uvreoretinal antigen. In contrast, only one of 15 patients with minimal retinopathy and none of the controls showed significant leucocyte-migration inhibition. Corneal and lenticular antigens did not evoke a cellular immune response in any of the tested individuals. These findings suggest that cell-mediated hypersensitivity to uveoretinal antigen may develop in diabetic patients with prolonged, progressive, simple or proliferative retinopathy. 相似文献
78.
Model systems for study of the action of adjuvants in immunodeficient states were developed in 10- to 14-day-old BALB/aj mice and aging BALB/aj mice (12 to 16 months). With sheep red blood cells as antigen polyadenylicpolyuridylic acid complexes (poly A:U) were found to be stimulatory in both the neonatal and aging mice. The effect of poly A:U was similar to that seen when 5 X 10(6) thymocytes from immunologically mature mice were given with antigen. Cell-free supernatant fluids induced by incubation of poly A:U with thymocytes likewise were capable of restoring the number of antibody-forming cells to normalcy in aging mice. 相似文献
79.
IH Page 《Canadian Metallurgical Quarterly》1977,61(1):203-206
The treatment of hypertension was discovered long before the mechanisms of the disease became known. Only recently has it been appreciated that blood pressure is controlled physiologically in many ways. Hypertension has suddenly achieved celebrity status. It is now recognized as the second leading cause of death in the United States. New programs have made the public aware of it and have prompted many individuals to have their blood pressure checked. Office diagnostic measures usually suffice to determine the presence of the disease. Treatment should generally be initiated with a slow-acting diuretic or with propranolol; other drugs may be added later. Treatment is a lifelong undertaking, and engaging the patient as a partner in the venture by means of home blood pressure measurements and an educational program contributes to its success. Treatment of hypertension is the first step in the prophylaxis of atherosclerosis. 相似文献
80.
Women's attitudes to mastectomy for breast cancer 总被引:1,自引:0,他引:1
One hundred patients who had been subjected to mastectomy for carcinoma were interviewed retrospectively to gauge their attitudes to any physical and/or emotional disabilities relating to their operation or disease. It was found that 40% of the patients had delayed for longer than a month after the onset of symptoms before seeking medical advice, but the reasons for this were not readily forthcoming. However, fear of mastectomy was not a common cause. Anxiety and embarassment due to an absent breast occurred in about one-third of patients, and did not diminish with time. Knowledge and the use of mammary prostheses was far from universal, and disturbingly only two-thirds were counselled in these matters by their medical advisers. Physical complications were common, particularly lymphoedema of the arm, and as expected this was closely related to the type and extent of treatment undertaken. 相似文献