Postbuckling of functionally graded cylindrical shells with tangential edge restraints and temperature-dependent properties

This paper presents an analytical approach to investigate the buckling and postbuckling behavior of functionally graded cylindrical shells subjected to thermal and axial compressive loads. Material properties are assumed to be temperature dependent and graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of constituents. The governing equations are established within the framework of classical thin shallow shell theory taking both geometrical nonlinearity in von Kármán–Donnell sense and initial imperfection into consideration. Thermal stability analysis also incorporates the effects of tangential edge constraints. A Galerkin procedure is applied to derive expressions of load-deflection relations from which the thermal buckling loads and postbuckling curves of the shells are obtained by an iteration. Effects played by material and geometrical properties, tangential stiffness, imperfection and buckling modes are discussed.     

Thermal Actuated Solid Tunable Lens

In this letter, the concept of driving tunable solid lens using microthermal actuator is presented. This microoptical device is composed of a flexible polydimethylsiloxane (PDMS) lens, silicon conducting ring, and silicon heater. The mismatching of coefficient of thermal expansion and stiffness between PDMS and silicon will lead to the deformation of polymer lens during heating, so as to further change its focal length. To demonstrate the feasibility of this approach, a microfabrication processes have been established to monolithically fabricate the present microoptical device. The typical experiment results show that the tunable focal length was up to 834 mum with an input current of 70 mA     

Organization of the disynaptic pathway from the anteroventral cochlear nucleus to the lateral superior olivary nucleus in the ferret

The medial nucleus of the trapezoid body (MNTB) is one of three major nuclei of the superior olivary complex and provides an important inhibitory input from the contralateral ear to the lateral superior olivary nucleus (LSO) in the initial binaural pathway for coding interaural intensity differences. The major input to the MNTB from the contralateral anteroventral cochlear nucleus (AVCN) involves giant, calyx-like endings that have a one-to-one relationship with cells in the MNTB as confirmed in the ferret in this study. The main objective of the present study was to define the subsequent organization of projections from cells receiving these calyx-like endings. Several anatomical tracers (Phaseolus vulgaris leucoagglutinin, dextran-biotin, and biocytin) were used that are transported both anterogradely and retrogradely within neuronal projections in order to define the organization of MNTB connections with the LSO in the adult ferret. Analysis focused on determining the topography in both the transverse and longitudinal planes of the projections. Focal tracer injections in the LSO resulted in retrograde labeling of a long, narrow column of cells in the MNTB. The orientation and location of labeled cells was dependent on the medial-lateral position of the injection site. In the rostral-caudal dimension of MNTB, there was no such topographic relation between the injection site and the position of labeled cells. Labeled cells in the MNTB were distributed more or less evenly in a longitudinal column regardless of whether the injection site was restricted to the rostral, middle or caudal part of the LSO. In keeping with this pattern, tracer injections in the MNTB resulted in bands of labeled axons that distributed endings throughout the rostral-caudal axis of the LSO. These bands or sheets varied in medial-lateral position relative to the location of the injection site, but lacked any such rostral-caudal gradient. Thus, overall the MNTB-LSO projections have a convergent-divergent pattern of organization. While MNTB cells receive singular calyx-like endings from the AVCN, LSO cells receive projections from a long column of cells in the MNTB. Implications for processing interaural intensity differences are discussed.     

Distribution of 127 edible plant species for antioxidant activities by two assays

Epidemiological studies have demonstrated the protective effects of fruit and vegetable consumption on human health. A total of 150 edible plants representing 127 species were evaluated for Trolox equivalent antioxidant capacity (TEAC) and superoxide scavenging (SOS) activity. Distributions of vegetables for TEAC and SOS were not continuous but highly skewed. TEAC values on a dry weight basis ranged from 0 to 2105 µmol TE g⁻¹ and SOS values ranged from 0 to 6206 µmol ascorbate equivalent (AE) g⁻¹. The majority of vegetables clustered within 200 µmol TE g⁻¹ and 400 µmol AE g⁻¹. Vegetable species were grouped into six classes after natural logarithm transformation of TEAC and SOS values. Most highly consumed vegetables fell in the very low to medium classes. Species in the very high class for both TEAC and SOS included leaves of Cedrela sinensis (Chinese cedar), Oroxylum indicum (Damocles tree), Cassia siamea (cassod tree) and Cassia tora (sickle senna). Edible plants high in antioxidant activity (AOA) were mostly perennial and underutilised crops, while commonly consumed vegetables were generally low in AOA. There is great potential to increase dietary antioxidants and improve human health through consumption of diverse vegetable species, especially those high in AOA. Copyright © 2006 Society of Chemical Industry     

Human papillomavirus infection and its relationship to recent and distant sexual partners

OBJECTIVE: To determine the relation between the detection of genital human papillomavirus (HPV) DNA and the number of new sexual partners in the last year, 1-5 years, and 5-10 years. METHODS: In a cross-sectional study, 298 women collected tampon specimens and completed self-answer questionnaires on the known risk factors for HPV infection, including the number of sexual partners during the last 1, 5, and 10 years. The tampons were analyzed for the presence of HPV DNA by polymerase chain reaction using L1 consensus primers. RESULTS: Ninety-two (30.9%) tampons were positive for HPV DNA. In univariate analysis, the presence of HPV DNA was associated with a younger age, single marital status, a previously abnormal or currently abnormal Papanicolaou smear, and one or more new sexual partners in the last year, 1-5 years, and 5-10 years. The presence of HPV DNA was not associated with education level, past pregnancy, current or past oral contraceptive use, or the age at first intercourse. In multivariate analysis, only the number of sexual partners during the last year and 1-5 years, and a previously abnormal Papanicolaou smear were associated with HPV. CONCLUSION: The presence of HPV DNA is best predicted by the number of new sexual partners in the last 5 years. Transiently detectable HPV DNA is one possible explanation for this observation.     

Production of tumor necrosis factor, interleukin-6 and prostaglandin E2 by LPS-stimulated rat bone marrow macrophages after thermal injury: effect of indomethacin

The effect of thermal injury on the in vitro production of TNF, IL-6, and PGE2 by bone marrow-derived, LPS-stimulated rat macrophages was studied. Thermal injury caused a general hyperactivity in the production of the mediators by the cells. Indomethacin, a cyclooxygenase inhibitor of PGE2 synthesis, inhibited the production of IL-6 and PGE2 but had no effect on the production of TNF. These results suggest that the observed low concentration of PGE2 produced by the cells was insufficient to cause inhibition of TNF synthesis; thus, the effect of indomethacin would be undetectable. The results also suggest that indomethacin may act directly in inhibiting the production of IL-6 by the macrophages. The hyperactive effect of thermal injury on the production of inflammatory mediators by newly differentiated bone marrow derived macrophages can be important in the overall systemic response to the insult.