616 research outputs found

    Organic Diode and Other Circuit Element Creation Through Variations of Poly(3,4-ethylenedioxythiophene)Synthesis

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    Fabricating semiconductor junction diodes can be costly in price and time. It typically involves long turn around time from the foundry, which requires precise machines and a clean room environment to prevent contamination from air born materials. This intensive process of fabricating diodes, means the cost will increase as the machines to process the semiconductor material need to become more precise. The proposed solution to the problem of cost and time is to create a printing system that is capable of printing diodes and circuits on various substrates. The experiments described in this thesis investigate the possible diode material, Poly(3,4-ethylenedioxythiophene), a polymer in aqueous dispersion. Variation in experiments with the weight ratios for the chemicals used for synthesis of this polymer are used as a benchmark to find the optimum weight ratios for the Poly(3,4-ethylenedioxythiophene) synthesis, to create an asymmetric rectifying diode, using continuous ink jet printing technology

    Lessons Learned from the Performance of a Degradable Shale Embankment: Case Study

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    Degradable shales are sedimentary rocks with properties that can vary from those of solid rock to soil like materials if subjected to wetting and drying cycles. If the potential for degradation of the shale is not identified on time, rock like particles could be used as strong embankment material. After wetting and drying cycles, degradation occurs and the initial large voids formed between the generally uniform rock particles are filled with smaller fragments, resulting in significant settlements and slope instability. This paper present a case study of a 40 foot (12.2m) approach embankment having 1.5H:1V slopes that was unintentionally constructed with degradable shale. Preliminary testing showed that even though some samples were clearly degradable shale other samples exhibited durability indexes greater than the values generally accepted as durable rock. After embankment completion a settlement monitoring program was instituted for the prescribed quarantine period prior to construction of the bridge abutments. The embankment settled more than initially predicted and finally stabilized after more than 1 feet (0.305m) of internal deformation. A laboratory testing program was developed to investigate the causes of the observed degradation

    Expression of gonadotropin receptor and growth responses to key reproductive hormones in normal and malignant human ovarian surface epithelial cells

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    Epidemiological data have implicated reproductive hormones as probable risk factors for ovarian cancer (OCa) development. Although pituitary and sex hormones have been reported to regulate OCa cell growth, no information is available regarding whether and how they influence normal ovarian surface epithelial (OSE) cell proliferation. To fill this data gap, this study has compared cell growth responses to gonadotropins and sex steroids in primary cultures of human OSE (HOSE) cells with those observed in immortalized, nontumorigenic HOSE cells and in OCa cell lines. Both malignant and normal cell lines/cultures responded equally well to the stimulatory actions of luteinizing hormone and follicle-stimulating hormone and to 17beta-estradiol and estrone, although the latter estrogen has a much lower affinity for estrogen receptor than does the former estrogen. In normal HOSE cell cultures/lines, 5alpha-dihydrotestosterone was found to be more effective than testosterone in stimulating cell growth, but in OCa cell lines, 5alpha-dihydrotestosterone and testosterone are equally potent. One OCa cell line, OVCA 433, was found to be nonresponsive to androgen stimulation. In general, primary cultures of normal HOSE cells exhibited the greatest hormone-stimulated growth responses (\u3e10-fold enhancement), followed by immortalized HOSE cell lines (4-5-fold enhancement) and by OCa cell lines (2-4-fold enhancement). Interestingly, progesterone (P4), at low concentrations (10(-11) to 10(-10) M), was stimulatory to HOSE and OCa cell growth, but at high doses (10(-8) to 10(-6) M), P4 exerted marked inhibitory effects. In all cases, cotreatment of a cell culture/line with a hormone and its specific antagonist blocked the effect of the hormone, confirming specificity of the hormonal action. Taken together, these data support the hypothesis that reproductive states associated with rising levels of gonadotropins, estrogen, and/or androgen promote cell proliferation in the normal OSE, which favors neoplastic transformation. Conversely, those states attended by high levels of circulating P4, such as that seen during pregnancy, induce OSE cell loss and offer protection against ovarian carcinogenesis

    Differential effects of insulin-like growth factor binding proteins-1, -2, -3, and -6 on cultured growth plate chondrocytes

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    Differential effects of insulin-like growth factor binding proteins-1, -2, -3, and -6 on cultured growth plate chondrocytes.BackgroundIn children with chronic renal failure (CRF), impairment of longitudinal growth is in part due to excess amounts of circulating high-affinity insulin-like growth factor binding proteins (IGFBPs) that might decrease or prevent insulin-like growth factor (IGF) binding to its signaling receptor. However, it appears from the clinical studies that various IGFBPs may have contrasting effects on longitudinal growth. Because of the potential importance of the IGFBPs as modulators of longitudinal growth in pediatric CRF, the aim of the present study was to investigate the biological effects of IGFBP-1, -2, -3, and -6 on cultured growth plate chondrocytes that express the type 1 IGF receptor.MethodsThe effects of exogenous IGFBPs on IGF-independent and IGF-dependent proliferation of rat growth plate chondrocytes in primary culture were investigated. Proliferation was assessed by colony formation of agarose-stabilized long-term suspension cultures and by the [3H]thymidine assay. The effects of IGFBPs on IGF-I binding and the binding of IGFBPs to chondrocytes were assessed by binding studies with radiolabeled proteins in monolayer culture.ResultsIntact IGFBP-1, IGFBP-2 and IGFBP-6 inhibited in equimolar concentration the IGF-I- and IGF-II-stimulated DNA synthesis and cell proliferation, whereas the biological activity of IGFBP-3 was complex. It had an IGF-independent antiproliferative effect and also inhibited IGF-dependent chondrocyte proliferation under coincubation conditions, whereas under preincubation conditions IGFBP-3 enhanced IGF-I-responsiveness. Studies on the mechanism by which IGFBP-3 potentiated IGF activity demonstrated that under preincubation conditions IGFBP-3 is capable to associate with the cell membrane and to facilitate IGF-I cell surface binding.ConclusionsIntact IGFBP-1, IGFBP-2 and IGFBP-6 act exclusively as growth inhibitors on IGF-dependent proliferation of growth plate chondrocytes. IGFBP-3, however, can either inhibit IGF-independent and IGF-dependent cell proliferation, or enhance IGF responsiveness of chondrocytes dependent on the temporal relationship to the IGF exposure

    Dyslipidaemia in children on renal replacement therapy

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    Background Information on lipid abnormalities in end-stage renal disease (ESRD) mainly originates from adult patients and small paediatric studies. We describe the prevalence of dyslipidaemia, and potential determinants associated with lipid measures in a large cohort of paediatric ESRD patients. Methods In the ESPN/ERA-EDTA registry, lipid measurements were available for 976 patients aged 2-17 years from 19 different countries from the year 2000 onwards. Dyslipidaemia was defined as triglycerides >100 mg/dL (2-9 years) or >130 mg/dL (9-17 years), high-density lipoprotein (HDL) cholesterol 145 mg/dL. Missing data were supplemented using multiple imputation. Results The prevalence of dyslipidaemia was 85.1% in peritoneal dialysis (PD) patients, 76.1% in haemodialysis (HD) patients and 55.5% among renal allograft recipients. Both low and high body mass index (BMI) were associated with a less favourable lipid profile. Younger age was associated with a worse lipid profile among PD patients. HDL levels significantly improved after transplantation, whereas no significant improvements were found for triglyceride and non-HDL levels. In transplant recipients, use of cyclosporin was associated with significantly higher non-HDL and HDL levels than tacrolimus usage (P 90 mL/min/1.73 m2 (P < 0.0001). Conclusions Dyslipidaemia is common among paediatric ESRD patients in Europe. Young age and PD treatment are associated with worse lipid profiles. Although lipid levels generally improve after transplantation, dyslipidaemia may persist due to decreased graft function, high BMI or to the use of certain immunosuppressant
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