53,544 research outputs found
The effect of Nafion film on the cathode catalyst layer performance in a low-Pt PEM fuel cell
A single--pore model for performance of the cathode catalyst layer (CCL) in a
PEM fuel cell is developed. The model takes into account oxygen transport
though the CCL depth and through the thin Nafion film, separating the pore from
Pt/C species. Analytical solution to model equations reveals the limiting
current density due to oxygen transport through the Nafion
film. Further, linearly depends of the CCL thickness, i.e., the
thinner the CCL, the lower . This result may explain unexpected
lowering of low--Pt loaded catalyst layers performance, which has been widely
discussing in literature.Comment: 11 page
Effects of Parasitics and Interface Traps On Ballistic Nanowire FET In The Ultimate Quantum Capacitance Limit
In this paper, we focus on the performance of a nanowire Field Effect
Transistor (FET) in the Ultimate Quantum Capacitance Limit (UQCL) (where only
one subband is occupied) in the presence of interface traps (),
parasitic capacitance () and source/drain series resistance ()
using a ballistic transport model and compare the performance with its
Classical Capacitance Limit (CCL) counterpart. We discuss four different
aspects relevant to the present scenario, namely, (i) gate voltage dependent
capacitance, (ii) saturation of the drain current, (iii) the subthreshold slope
and (iv) the scaling performance. To gain physical insights into these effects,
we also develop a set of semi-analytical equations. The key observations are:
(1) A strongly energy-quantized nanowire shows non-monotonic multiple peak C-V
characteristics due to discrete contributions from individual subbands; (2) The
ballistic drain current saturates better in the UQCL compared to CCL, both in
presence and absence of and ; (3) The subthreshold slope does
not suffer any relative degradation in the UQCL compared to CCL, even with
and ; (4) UQCL scaling outperforms CCL in the ideal
condition; (5) UQCL scaling is more immune to , but presence of
and significantly degrades scaling advantages in the UQCL.Comment: Accepted at IEEE Transactions on Electron Device
Building ArtsSmarts' Research Capacity: An Interim Report
In 2006, the Canadian Council on Learning (CCL) created an initiative to build Canada's capacity to conduct research on learning, inviting not-for profit organizations to apply for Researcher in Residence grants. ArtsSmarts was one of the successful grant applicant organizations. Saad Chahine was hired by ArtsSmarts to take on the researcher-in-residence role. Several meetings resulted in the development of a work plan (Appendix A) and an outline of the various activities to be carried out by the researcher-in-residence. The work plan was approved by CCL, and the residency commenced in June 2007. What follows is an interim report on the residency, documenting what has been accomplished since June 2007, and providing direction for continuing to build ArtsSmarts' research capacity going forward
Columnar cell lesions and subsequent breast cancer risk: a nested case-control study
Introduction: Histologic and genetic evidence suggests that at least some columnar cell lesions (CCL) of the breast represent precursor lesions in the low-grade breast neoplasia pathway. However, the risk of subsequent breast cancer associated with the presence of CCL in a benign breast biopsy is poorly understood.Methods The authors examined the association between the presence of CCL and subsequent breast cancer risk in a nested case-control study of benign breast disease (BBD) and breast cancer within the Nurses' Health Studies (394 cases, 1,606 controls). Benign breast biopsy slides were reviewed by pathologists and CCL presence assessed. Logistic regression was used to compute odds ratios (ORs) and 95% confidence intervals (CIs) for the association between CCL and breast cancer risk. Results: Women with CCL (140 cases, 448 controls) had an increased risk of breast cancer compared with those without CCL (OR = 1.44, 95% CI: 1.14 to 1.83), although this was attenuated and became non-significant after adjustment for the histologic category of BBD (OR = 1.20, 95% CI: 0.94 to 1.54). CCL presence was associated with the greatest risk of breast cancer for those with nonproliferative BBD (OR = 1.36, 95% CI: 0.79 to 2.37) and the lowest risk for those with atypical hyperplasia (AH) (OR = 1.10, 95% CI: 0.65 to 1.87); however, this apparent heterogeneity in risk across BBD categories was not significant (P for interaction between CCL presence and BBD category = 0.77). Conclusions: These results provide evidence that CCL may be an important marker of breast cancer risk in women with BBD but suggest that CCL do not increase breast cancer risk independently of concurrent proliferative changes in the breast
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