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  1. Free, publicly-accessible full text available July 3, 2024
  2. Abstract Paper-based electrochemical sensors provide the opportunity for low-cost, portable and environmentally friendly single-use chemical analysis and there are various reports of surface-functionalized paper electrodes. Here we report a composite paper electrode that is fabricated through designed papermaking using cellulose, carbon fibers (CF), and graphene oxide (GO). The composite paper has well-controlled structure, stable, and repeatable properties, and offers the electrocatalytic activities for sensitive and selective chemical detection. We demonstrate that this CF/GO/cellulose composite paper can be reduced electrochemically using relatively mild conditions and this GO reduction confers electrocatalytic properties to the composite paper. Finally, we demonstrate that this composite paper offers sensing performance (sensitivity and selectivity) comparable to, or better than, paper-based sensors prepared by small-batch surface-modification (e.g., printing) methods. We envision this coupling of industrialized papermaking technologies with interfacial engineering and electrochemical reduction can provide a platform for single-use and portable chemical detection for a wide range of applications. 
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  3. This study collected summer meltwater runoff samples from several glacier watersheds of the northeast Tibetan Plateau during June-July 2017, and measured the concentrations of 17 trace elements (Li, Be, Sc, V, Cr, Co, Ni, Cu, Zn, Ga, Rb, Mo, Cd, In, Sb, Cs, Ba) in meltwater suspended particulate matter (SPM), in order to reveal the elemental concentration, spatial distribution, and water quality in remote glacier watershed under regional anthropogenic activities. Results showed that, the concentration of heavy metal elements was relatively high in Yuzhufeng Glacier basin, ranging from 0.57 μg/L (In) to 1,551.6 μg/L (Ba), whereas in Qiyi Glacier basin it was the lowest, ranging from 0.02 to 85.05 μg/L; and relatively medium in other glacier watersheds, with total elemental concentration varying from 1,503.9 to 1726.2 μg/L. Moreover, enrichment factors (EFs) of SPM heavy metals showed significantly higher value in the downstream than that of upper glacier region of the watershed. Most heavy metals with low EFs mainly originated from crust dust, while others with higher EFs (e.g., Cd, Sb) probably originated from anthropogenic sources. Spatially, the EFs of heavy metals were higher in Yuzhufeng and Laohugou Glacier basins; while in other regions the EFs were relatively low, which may be caused by regional land-surface and atmospheric environmental differences surrounding the various glacier watersheds. Compared with other remote locations in global range, heavy metals level (e.g., Cu, Ni, and Zn) in this region is relatively higher. Meanwhile, we find that, though the water quality of the glacier basin in northeast Tibetan Plateau was relatively clean and pollution-free, it is still obviously affected by regional anthropogenic activities. Mining activities, transportation and natural weathering and erosion processes in the study areas have important effects on the content of heavy metal pollutants of river-water SPM in the glacier watershed. Moreover, backward air-mass trajectories demonstrated the potential atmospheric pollutants transport from the surrounding cities and suburbs, to deposit in the snowpack and glaciers, and then melted out and released into meltwater runoff. This study provides a new perspective on more complete view of heavy metals distribution in glacier watershed, and new understanding for the cryosphere water environment evaluation in the Tibetan Plateau region. 
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  5. Sampling based planning is an important step for long-range navigation for an autonomous vehicle. This work proposes a GPU-accelerated sampling based path planning algorithm which can be used as a global planner in autonomous navigation tasks. A modified version of the generation portion for the Probabilistic Road Map (PRM) algorithm is presented which reorders some steps of the algorithm in order to allow for parallelization and thus can benefit highly from utilization of a GPU. The GPU and CPU algorithms were compared using a simulated navigation environment with graph generation tasks of several different sizes. It was found that the GPU-accelerated version of the PRM algorithm had significant speedup over the CPU version (up to 78×). This results provides promising motivation towards implementation of a real-time autonomous navigation system in the future. 
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    Here, in ionically conducting Na 0.5 Bi 0.5 TiO 3 (NBT), we explore the link between growth parameters, stoichiometry and resistive switching behavior and show NBT to be a highly tunable system. We show that the combination of oxygen ionic vacancies and low-level electronic conduction is important for controlling Schottky barrier interfacial switching. We achieve a large ON/OFF ratio for high resistance/low resistance ( R HRS / R LRS ), enabled by an almost constant R HRS of ∼10 9 Ω, and composition-tunable R LRS value modulated by growth temperature. R HRS / R LRS ratios of up to 10 4 and pronounced resistive switching at low voltages (SET voltage of <1.2 V without high-voltage electroforming), strong endurance (no change in resistance states after several 10 3 cycles), uniformity, stable switching and fast switching speed are achieved. Of particular interest is that the best performance is achieved at the lowest growth temperature studied (600 °C), which is opposite to the case of most other perovskite oxides for memristors, where higher growth temperatures are required for optimum performance. This is understood based on the oxygen vacancy control of interfacial switching in NBT, whereas a range of other mechanisms (including filamentary switching) occur in other perovskites. The study of NBT has enabled us to determine key parameters for achieving high performance memristors. 
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