RESUMO
In this paper, the performance of Cu-(In,Ga)-S2 (CIGS2) solar cells with adjusting composite [Cu]/([Ga] + [In]) (CGI)-ratio absorber was explored and compared through an improved three-stage co-evaporation technique. For co-evaporating CIGS2 absorber as a less toxic alternative to Cd-containing film, we analyzed the effect of the CGI-ratio stoichiometry and crystallinity, and explored its opto-electric sensing characteristic of individual solar cell. The results of this research signified the potential of high-performance CIGS2-absorption solar cells for photovoltaic (PV)-module industrial applications. For the optimal CIGS2-absorption film (CGI = 0.95), the Raman main-phase signal (A1) falls at 291 cm-1, which was excited by the 532 nm line of Ar+-laser. Using photo-luminescence (PL) spectroscopy, the corresponding main-peak bandgaps measured was 1.59 eV at the same CGI-ratio film. Meanwhile, the best conversion efficiency (η = 3.212%) and the average external quantum efficiency (EQE = 51.1% in the visible-wavelength region) of photo-electric properties were achieved for the developed CIGS2-solar cells (CGI = 0.95). The discoveries of this CIGS2-absorption PV research provided a new scientific understanding of solar cells. Moreover, this research undeniably contributes to a major advancement towards practical PV-module applications and can help more to build an eco-friendly community.
RESUMO
AIM: To evaluate the effects of change of ambient temperature on emergency department (ED) patient visits. METHODS: This prospective observational study was conducted in the ED of National Taiwan University Hospital from January 2002 to January 2007. The daily ED patient numbers of different triage levels in different service specialties were collected and correlated with the daily average temperature (T) and change in temperature (deltaT) compared with the previous day. A univariate analysis was performed with the Pearson correlation and a multivariate analysis with multiple linear regression analysis. RESULTS: A total of 505,224 patient visits were included in this study. On univariate analysis, there was no significant correlation between T and the ED volume (r = 0.012, p = 0.608), but there was a significant correlation between deltaT and ED volume (r = 0.109, p<0.001). On multivariate analysis, deltaT and holidays were identified as independent predictors of ED volume. We established the following formula in predicting the ED patient number: y = 265.42 + (0.06 x T) + (2.57 x deltaT) + (59.77 x holiday). There was a positive association between T and the trauma patient number, while there was a negative association between T and medical and paediatric patient numbers. On the triage level, a low T was associated with increased patient triage level, while no significant association was noted between deltaT and the proportion in any triage level. CONCLUSIONS: Our study demonstrated that ambient temperature had differential effects on ED patient visits of different specialties and severities.
