Effects of Gas-Particle Partitioning on Refractive Index and Chemical Composition of <i>m</i>‑Xylene Secondary Organic Aerosol

The formation of secondary organic aerosols (SOAs) contains partitioning processes of the oxidation products between the gas and particle phases, which could change the particle-phase composition when particles grow. However, the effects of these processes on the optical properties of SOA remain poorly understood. In this study, we performed smog chamber experiments to investigate the effects of gas-particle partitioning (GPP) on the refractive index (RI) and chemical composition of the <i>m</i>-xylene SOA. Here, we show that the GPP processes, as organic mass increases, can increase the proportions of semivolatile and intermediate-volatility organic compounds (SVOCs and IVOCs) in the particle phase and result in the decrease of SOA RI real part for 0.09 ± 0.02 (without seeds) and 0.15 ± 0.02 (with seeds). This indicates that the SOA optical properties are closely related to the total organic mass and molecular-level composition. In addition, the presence of inorganic seeds promotes the GPP to the particle phase and hence further decreases the RI real part for 0.05 ± 0.02. As pre-existing aerosols are ubiquitous in the ambient atmosphere, it is suggested that there should be a certain correction when the SOA RI of previous laboratory studies is applied to air quality and climate models

Facile Synthesis of Highly Active Three-Dimensional Urchin-like Pd@PtNi Nanostructures for Improved Methanol and Ethanol Electrochemical Oxidation

Exploitation of highly active catalysts for alcohol electrooxidation is urgent for direct alcohol fuel cells (DAFCs). In this research, a facile and mild synthetic approach is utilized to control and tailor the morphology of the three-dimensional (3D) urchin-like Pd@PtNi nanostructures (NSs), and the formation mechanism of the as-prepared nanostructures is expounded in detail. The Pd@PtNi NSs exhibit outstanding electrochemical properties and remarkable durability toward both methanol and ethanol oxidation reaction (MOR and EOR) in alkaline solution. The electrochemically active surface area (ECSA) of the Pd@PtNi NSs is 59.5 m² g^–1, and their mass activities for MOR and EOR are 1614.3 and 1502.3 mA mg^–1, respectively, which are much higher than those of their ternary or binary alloy counterparts as well as commercial Pt black catalysts. Moreover, it still retains high current densities after catalyzing 10 000 s, while the current densities of other nanocatalysts reduce to nearly zero. The outstanding electrochemical activities and durability are owing to the specific 3D urchin-like nanostructures providing enormous active sites for catalytic reaction and the synergy effects between Pt, Pd, and Ni atoms. The 3D urchin-like Pd@PtNi NSs will enrich the electrocatalysts for DAFCs

A Novel Mechanism for NO₂‑to-HONO Conversion on Soot: Synergistic Effect of Elemental Carbon and Organic Carbon

Soot, mainly composed of elemental carbon (EC) and organic carbon (OC), plays an important role in the formation of atmospheric nitrous acid (HONO) through the heterogeneous reaction with nitrogen dioxide (NO2). In this study, we found that fresh soot exhibits a much higher HONO yield than its EC or OC components alone. This does not support the previously proposed hydrogen-abstraction mechanism for HONO formation at a single reductive site on the soot surface. Based on our observations of infrared (IR) spectroscopy and flow tube experiments, we propose a new mechanism that involves the synergistic participation of two sites: one located at OC and the other at EC. They provide a proton and an electron necessary for NO2 reduction to HONO, respectively, via a proton-coupled electron transfer pathway. This mechanism highlights the important roles of OC and EC in HONO release from soot and underscores the significant implications of soot compositions in atmospheric oxidative capacity

Serum Uric Acid and Renal Transplantation Outcomes: At Least 3-Year Post-transplant Retrospective Multivariate Analysis

<div><p>Since the association of serum uric acid and kidney transplant graft outcome remains disputable, we sought to evaluate the predictive value of uric acid level for graft survival/function and the factors could affect uric acid as time varies. A consecutive cohort of five hundred and seventy three recipients transplanted during January 2008 to December 2011 were recruited. Data and laboratory values of our interest were collected at 1, 3, 6, 12, 24 and 36 months post-transplant for analysis. Cox proportional hazard model, and multiple regression equation were built to adjust for the possible confounding variables and meet our goals as appropriate. The current cohort study lasts for 41.86 ± 15.49 months. Uric acid level is proven to be negatively associated with eGFR at different time point after adjustment for age, body mass index and male gender (standardized β ranges from -0.15 to -0.30 with all P<0.001).Males with low eGFR but high level of TG were on CSA, diuretics and RAS inhibitors and experienced at least one episode of acute rejection and diabetic issue were associated with a higher mean uric acid level. Hyperuricemia was significantly an independent predictor of pure graft failure (hazard ratio=4.01, 95% CI: 1.25-12.91, P=0.02) after adjustment. But it was no longer an independent risk factor for graft loss after adjustment. Interestingly, higher triglyceride level can make incidence of graft loss (hazard ratio=1.442, for each unit increase millimoles per liter 95% CI: 1.008-2.061, P=0.045) and death (hazard ratio=1.717, 95% CI: 1.105-2.665, P=0.016) more likely. The results of our study suggest that post-transplant elevated serum uric acid level is an independent predictor of long-term graft survival and graft function. Together with the high TG level impact on poor outcomes, further investigations for therapeutic effect are needed.</p></div

Hazard ratios of graft loss, graft failure, and death with UA/hyperuricemia in Cox proportional hazard models.

<p>Graft loss includes allograft failure and death; multivariate variables include: age, gender, BMI, HLA mismatch, introduction regimen, immunosuppressive agent protocol, diabetic mellitus, dialysis type, DGF, infection and acute rejection episode; abbreviations as previous tables; HR, hazard ratio.</p

Kaplan-Meier survival curve estimates for pure graft survival.

<p>Excluding the dead with functioning kidney, we could observe greater variance between the two groups.</p

1-month post-transplant eGFRs and UAs for patients of different outcomes.

<p>All P values are the results compared with recipients with nice prognosis group.</p

Kaplan-Meier survival curve estimates for graft loss.

<p>Hyperuricemic group survival curve was significantly (P = 0.007) lower than that of normouricemic group.Graft loss was defined as graft failure (return to dialysis) or death with functioning graft.</p

Journal of Mennonite studies

<p>All eGFRs of the 5 patients are lower than 10. One of them was having an acute rejection when tested for eGFR, the other 4 patients were experiencing DGF, 2 of them returned to dialysis eventually and the other 2 had recovered 2 months later. (A) The group of recipients went through allograft failure or death eventually. (B) The group of patients only suffered allograft failure.</p

Factors could impact UA level and risk factors for hyperuricemia.

<p>Abbreviations as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0133834#pone.0133834.t001" target="_blank">Table 1</a>; variables assignment for logistic regression: Dialysis type (prensence for peritoneal; lack for hemodialysis)</p