Delamination Buckling of Composite Conical Shells Under External Pressure

Airframe construction in conical form is the most desired shape of flight hardware due to their low drag profileand are located at the fore-end region of flight vehicles encountering high drag loads. Owing to their tailoringcapability, materials with orthotropic mechanical properties are preferred choice. Delamination defects formed inthem while manufacturing or when subjected to loads would unfavorably influence the mechanical performanceof the orthotropic airframe. In the current work, FE simulation of delamination which is embedded in orthotropiccone shaped shells under external pressure load is performed as per the method cited in published literature. A layer wise element based on shell theory has been used and the effect of delamination size and its through the thickness position on the mechanical performance of the cone shaped shell is investigated. Circumferential and rectangular shapes of defects have been simulated. The investigation is performed for metal and composite materials with 3 types of stacking sequences generally used in practical designs. Verification of the procedure is carried out by equating with the procedure cited in published studies on shells of thin orthotropic cylinders. The eigen value of the first mode is taken as the critical buckling factor under external pressure. The buckling factor of the delaminated cone is normalized with the buckling factor of the ideal cone. The normalized buckling factor is showed graphically with the normalised defect size. Global, as well as local buckling and also symmetric as well as asymmetric buckling shapes, are observed in the results of the simulation. Shift from global mode to local mode of buckling is also observed in certain cases. Drastic reduction in buckling capability with the local mode is observed when the defect location is close to the surface and more prominent for an outer surface case

Testicular phosphatase activity in rats treated with cyproterone acetate & flutamide

PIP: Cyproterone acetate (CPA) and flutamide (F), 2 antiandrogens were tested in the rat, to determine their effect on acid (ACP) and alkaline (ALP) phosphatase activity. 70 fertile male rats were injected with either CPA, F, or testosterone propionate (TP) at either 2.5 or 10 mg. TP was injected either alone or in combination with the others. Histological examinations of the testes were performed. Spermatogenesis was arrested and Leydig cells atrophied in animals treated with CPA or F. Histochemical examination revealed that CPA enhanced ALP and ACP in the testes while F decreased ALP and ACP. TP treatment in combination with either antiandrogens was unable to overcome their effect. The changes in the 2 phosphatases depending on which antiandrogen was injected suggests different modes of action

An assessment of inhibin-like activity secreted by Sertoli cells in culture using castrated adult male rats

Sertoli cells isolated from testes of 16-18 days old male rats were maintained in culture. Incubation media from these culture were pooled on day 7 and tested for its inhibin-like activity either with (SCCM) or after charcoal treatment (CSCCM) in castrated adult male rats. The assay was based on the tacit assumption that SCCM or CSCCM would specifically lower circulating blood serum levels of FSH. Subcutaneous (sc)injections of CSCCM at a dose level of 1 mg protein per rat, per day, × 3 days caused a specific suppression of FSH levels, while lower dosages of CSCCM (Protein content of 300 µg or 600 μg/rat/day, × 3 days) were without any affect on basal levels of FSH and LH. SCCM was ineffective at all dose levels tested. Intracardiac injections of varying doses of LHRH (25 to 400 ng/rat) to CSCCM pre-treated rats (200 μg/rat/day, × 3 days) failed to increase the levels of LH and FSH. These results support the presence of inhibin like activity in SCCM by a bioassay procedure alternate to in vitro pituitary cell culture system used by other investigators

Effect of testosterone, estradiol-17β, and 5α-dihydrotestosterone on inhibin production by sertoli cells in culture

Inhibin activity in charcoal-extracted spent culture medium of Sertoli cells in Primary culture (CSCCM) was monitored by following the temporal inhibition of serum levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in normal adult male rats. Subcutaneous injection of CSCCM reduced LH and FSH levels within 15 min and maintained the inhibition up to 10 hr. No selective suppression of FSH was observed. The model was used to assess inhibin activity in CSCCM from Sertoli cell cultures incubated with 5α-dihydrotestosterone (DHT), testosterone (T), and estradiol -17β (E2) (5 μg/ml) for 24 hr. CSCCM from T and E2 treated groups suppressed gonadotropins while the group exposed to DHT failed to elicit any inhibition. DHT seems to inhibit the release of inhibin by Sertoli Cells

Carbohydrate metabolism in human fallopian tubes

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