In this paper, a simple approach without a prereduction of graphene oxide was exploited to prepare a graphenedoped TiO 2 film for dye-sensitized solar cells (DSSCs). The performance measurement of the DSSCs showed that the incorporation of graphene could increase the short-circuit current density and power conversion efficiency by 52.4 and 55.3%, respectively. Furthermore, it was demonstrated that the performance enhancement was due to the promoting effect of graphene on electron transfer instead of the increase of dye loading in TiO 2 /graphene composite films. However, graphene can also absorb solar light, which could lead to the decrease of light harvest of dye molecules and thus a negative effect on the power conversion efficiency of DSSCs. Furthermore, graphene might decrease the actual dye loading on TiO 2 in a TiO 2 /graphene film, which can also make a negative contribution to the conversion efficiency. As a result, the promoting effect of graphene is strongly dependent on its content; namely, the efficiency of DSSCs increases to the maximum value and then decreases with increasing graphene content in TiO 2 /graphene composites.

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BackgroundBlunt traumatic brachial plexus injuries (BTBPI) are severe peripheral nerve injuries which present in a small portion of trauma patients but can result in long-term neurological disability and severe chronic pain.ObjectiveThe goal of this study was to describe the epidemiology of BTBPI in a northern rural setting caused by motor-powered collisions, and to determine the relative risk of these injuries in shielded (cars, trucks, vans, and so on) and unshielded vehicles (snowmobiles, all-terrain vehicles and motorcycles).MethodsThis retrospective study describes the epidemiology of BTBPI caused by motor-powered collisions and treated at two level II trauma centers in northeast Minnesota and determines the relative risk of these injuries in shielded (cars, trucks, vans, and so on) and unshielded vehicles (snowmobiles, all-terrain vehicles and motorcycles). We hypothesized unshielded motor vehicle crashes in rural areas are at an increased risk of incurring BTBPI.ResultsOut of all injuries resulting from motor-powered collisions in a 20-year period (9951), BTBPIs were found in 63 trauma patients, a prevalence of 0.6%. The rate of BTBPI involving unshielded vehicles (1.0%) was significantly higher than those involving a shielded vehicle (0.4%) and primarily occurred in rural areas (70%).ConclusionsUnshielded vehicle crashes, particularly snowmobiles, have the highest risk for BTBPI in our rural region. The overall incidence of these injuries appears to be declining.Level of evidenceLevel III.