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Open Access Publications from the University of California

Scholarly Works (44 results)

  • Article
  • Peer Reviewed
Recent Work (2019)
Herein, three small molecule (SM)-acceptors (POIT-IC, POIT-IC2F, and POIT-IC4F) are developed by combining the side-chain engineering located on the sp3-hybridized carbon atoms of the fused-ring core and the fluorination of end groups. From ITIC to POIT-IC, POIT-IC2F, and then to POIT-IC4F, the SM-acceptors show gradually broadened absorption spectra, increased maximum extinction coefficient, crystallinity, and electron mobilities due to the synergistic effects of side-chain engineering and fluorination. Compared with nonfluorinated ITIC and POIT-IC, as fluorination broadens the molecular spectra, POIT-IC2F and POIT-IC4F with alkoxyphenyl side chains show less decreased LUMO levels than IT-IC2F and IT-IC4F with alkylphenyl side chains, which are conducive to both higher Voc and Jsc for organic solar cells (OSCs). Combined with polymer donor PM6, the POIT-IC4F-based OSCs achieve a device efficiency of up to 13.8% with a high Voc of 0.91 V and Jsc of 20.9 mA cm−2, which are significantly higher than that of the control OSCs based on ITIC (8.9%), POIT-IC (10.1%), or IT-IC4F (12.2%). An efficiency of 13.8% is one of the highest PCEs reported for the annealing-free OSCs. Our results show that the synergistic effects of side-chain engineering and fluorination on SM-acceptor can simultaneously broaden spectral response and minimize voltage loss of OSCs and ultimately achieve high device efficiency.
    Cover page: Synergistic Effects of Side-Chain Engineering and Fluorination on Small Molecule Acceptors to Simultaneously Broaden Spectral Response and Minimize Voltage Loss for 13.8% Efficiency Organic Solar Cells
    • Article
    • Peer Reviewed
    UC Davis Previously Published Works (2015)
    PPM1D phosphatase, also called wild-type p53-induced phosphatase 1, promotes tumor development by inactivating the p53 tumor suppressor pathway. RBM38 RNA-binding protein, also called RNPC1 and a target of p53, inhibits p53 messenger RNA (mRNA) translation, which can be reversed by GSK3 protein kinase via phosphorylation of RBM38 at serine 195. Here we showed that ectopic expression of RBM38 increases, whereas knockdown of RBM38 inhibits, PPM1D mRNA translation. Consistent with this, we found that RBM38 directly binds to PPM1D 3'-untranslated region (3'-UTR) and promotes expression of a heterologous reporter gene that carries PPM1D 3'-UTR in a dose-dependent manner. Interestingly, we showed that PPM1D directly interacts with and dephosphorylates RBM38 at serine 195. Furthermore, we showed that PPM1D modulates p53 mRNA translation and p53-dependent growth suppression through dephosphorylation of RBM38. These findings provide evidence that the crosstalk between PPM1D and RBM38, both of which are targets and modulators of p53, has a critical role in p53 expression and activity.
      Cover page: PPM1D phosphatase, a target of p53 and RBM38 RNA-binding protein, inhibits p53 mRNA translation via dephosphorylation of RBM38.
      • Article
      • Peer Reviewed
      UC Davis Previously Published Works (2015)
      Many different approaches have been suggested for the assessment of organic pollution and related water quality variables. However, many methods used to assess organic pollution cannot qualitatively estimate the degree of importance of each pollutant. Water quality identification indices can provide comprehensive water quality information, which is both qualitative and quantitative, especially for areas worse than Grade V of the National Surface Water Quality Standard of China. However, this method considers every indicator equally, without considering the degree of importance of each parameter. Consequently, in this study, the entropy weight method was combined with the water quality identification index method. The improved comprehensive water quality identification index was applied to a water quality data-set for the Wen-Rui Tang River in China, which was generated in 2009 during six months of monitoring at 16 different sites and included seven parameters. The results indicated that the improved comprehensive water quality identification index provided an objective evaluation of each water quality indicator. Understanding the significance of each water quality parameter will help to implement more effective water quality improvement plans.
        Cover page: Innovative approach for the development of a water quality identification index—a case study from the Wen-Rui Tang River watershed, China
        • Article
        • Peer Reviewed
        Recent Work (2018)
        The gross primary production (GPP) in tropical terrestrial ecosystems plays a critical role in the global carbon cycle and climate change. The strong 2015–2016 El Niño event offers a unique opportunity to investigate how GPP in the tropical terrestrial ecosystems responds to climatic forcing. This study uses two GPP products and concurrent climate data to investigate the GPP anomalies and their underlying causes. We find that both GPP products show an enhanced GPP in 2015 for the tropical terrestrial ecosystem as a whole relative to the multiyear mean of 2001–2015, and this enhancement is the net result of GPP increase in tropical forests and decrease in nonforests. We show that the increased GPP in tropical forests during the El Nino event is consistent with increased photosynthesis active radiation as a result of a reduction in clouds, while the decreased GPP in nonforests is consistent with increased water stress as a result of a reduction of precipitation and an increase of temperature. These results reveal the strong coupling of ecosystem and climate that is different in forest and nonforest ecosystems and provide a test case for carbon cycle parameterization and carbon-climate feedback simulation in models.
          Cover page: Response of Tropical Terrestrial Gross Primary Production to the Super El Niño Event in 2015
          • Article
          • Peer Reviewed
          UC Irvine Previously Published Works (2013)
            Cover page: Resting-state functional connectivity and reading abilities in first andCreative Commons 'BY' version 4.0 license
            • Article
            • Peer Reviewed
            UC Davis Previously Published Works (2021)
            Integrated source apportionment and risk assessment of metals is of great importance for contamination source control and remediation at the regional watershed scale. To identify metal sources and source-specific ecological risks, sediments were collected in the Wen-Rui Tang urban watershed for metal analysis. Risk assessment showed considerable and extremely high risk for Cu and Cd with large spatial variation. Positive matrix factorization model extracted three main sources with reasonable prediction efficacy for metal concentrations. Due to different toxicity coefficients for various metals, the low concentration contribution of source factor 2 (27.2%) contributed 83.7% of total risk, while a high concentration loading for factor 3 (40.8%) only contributed 4.6% to total risk. Predicted source-specific risk was similar to determined risk level for Cr, Ni and Pb; however, Cu and Cd were predicted with decreased risk, while Zn had increased risk. Triangular fuzzy number (TFN) coupled with stochastic simulation showed elevated trend in risk simulation for Cd and Cu when compared with determined risk. The uncertainties for risk evaluation appear to result from spatial variations in metal concentrations. Source apportionment and specific-risk assessment results suggest that different strategies may be required to address mitigation of elevated metal concentrations versus ecological risk.
              Cover page: Integrated source-risk and uncertainty assessment for metals contamination in sediments of an urban river system in eastern China
              • Article
              • Peer Reviewed
              UC Davis Previously Published Works (2018)
              With the attractive feature of guaranteeing maximum network throughput, backpressure routing has been widely used in wireless communication networks. Motivated by the backpressure routing, in this paper, we propose a delay-based traffic signal control algorithm in transportation networks. We prove that this delay-based control achieves optimal throughput performance, same as the queue-based traffic signal control in the literature. However, a vehicle at a lane whose queue length remains very small may be excessively delayed under the queue-based signal control. Our delay-based backpressure control can deal with the excessive delays and achieve better fairness with respect to delay while still guaranteeing throughput optimality. Moreover, a general weighted control scheme combining the queue-based and delay-based schemes is also investigated, to provide a more flexible control according to the quality of service requirements. Numerical results explore their performance under both homogeneous and heterogeneous traffic scenarios.
                Cover page: Delay-Based Traffic Signal Control for Throughput Optimality and Fairness at an Isolated IntersectionCreative Commons 'BY-NC-ND' version 4.0 license
                • Article
                Journal of Citrus Pathology, Volume 1, Issue 1 (2014)

                The updated PhyloChipTM G3 were used to explore the differences in the relative abundance and phylogenetic diversity of the bacterial communities associated with HLB-affected citrus plants in the field over a growing season and those treated with antibiotic combinations of AG (Ampicillin at 1000 mg/L and Gentamicin at 100 mg/L) and PS (Penicillin at 1000 mg/L and Streptomycin at 100 mg/L). Both antibiotic treatments resulted in significantly lower Las bacterial titers (Pr<0.05) and their hybridization scores. Of the 50,000+ available operational taxonomic units (OTUs) on PhyloChip™ G3, 7,028 known OTUs in 58 phyla were detected from the field plants, and 7,407 OTUs in 53 phyla from the inoculated potted plants. Proteobacteria was the constantly dominant phylum of bacteria (38.7%~44.1%) vying for prevalence based on the season, followed by Firmicutes (23.5%~29.0%), Actinobacteria (12.4%~16.1%), Bacteroidetes (6.2%~6.6%) and Cyanobacteria (2.3%~3.2%). Circular tree comparing the Las-free and the Las-infected samples indicated that only 17 families present in the Las-free plants, such as Cyanobacteriaceae; but more than 137 families detected in the Las-infected plants, such as Staphylococcaceae and Pseudonocardiaceae. Cyanobacteria are believed to be responsible for introducing oxygen into the atmosphere and fixing nitrogen and phosphorus assimilation for plant growth. Both Staphylococcaceae and Pseudonocardiaceae were recognized as an emerging opportunistic pathogen of plant and animals. When compared to the bacterial populations in the leaves of citrus trees receiving the water control treatment, the Bacteroidete population decreased (Pr<0.05) by 59.6% and 51.8% in the plants receiving AG and PS treatments, respectively. The overall diversity of bacteria also decreased with the antibiotic treatments. Bacterial cells in close proximity may be able to modify their microenvironment; thus, making the composition of the microbial community an important factor in the ability of Las to cause HLB progression. A low Las level was seen as a both a seasonal fluctuation, part of the bacterial population dynamics, and as a response to the antibiotic treatments.

                  Cover page: Characterization of the microbial community structure in ‘Candidatus Liberibacter asiaticus’-infected citrus plants treated with antibioticsCreative Commons 'BY' version 4.0 license
                  • Article
                  • Peer Reviewed
                  UC Berkeley Previously Published Works (2022)
                    Cover page: Dual Visisble Light Photoredox and Gold-Catalyzed Arylative Ring Expansion
                    • Article
                    • Peer Reviewed
                    UC Davis Previously Published Works (2015)
                    Most traditional linear regression models ignore local variations of spatial data. In this study, a new technique called geographically weighted regression model (GWR) was introduced to evaluate the impacts of land use on surface water. The reason for the spatial variations of relationships between land use and water quality were explored. Meanwhile, the adjusted R2, Akaike information criterion (AICc) and spatial autocorrelation index (Moran's I) of residuals were compared with ordinary least squares model (OLS) to verify if the GWR model is better than OLS in the prediction accuracy and the capacity of conducting spatial autocorrelation. The results showed that impact of the same types of land use on water quality changes in direction or size along with the variation of spatial position. For example, the relationships between TN and agricultural land in Wen-Rui Tang River showed a positive correlation in countryside and negative correlation in urban area in GWR models. The absolute values of regression coefficients in old downtown area were higher than other places. In the GWR model of dissolved oxygen (DO) and population density, the relationships were negative in the whole study area, which was consistent with the OLS results, and the effect of population density on DO is greater in suburban and rural areas. The reason for these spatial changes over different sub-watersheds indicated that the changes of land use percentage and the varied main pollution sources are fundamental factors. Furthermore, the adjusted R2 and AICc values from the 80 established models confirmed that as a local statistical model, GWR had better prediction accuracy than OLS model and could better reflected the actual spatial characteristics.
                      Cover page: Evaluating the impacts of land use on surface water quality using geographically weighted regression
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