The dependence of new particle formation rates on the interaction between cluster growth, evaporation, and condensation sink

New particle formation (NPF) is one of the major contributors to atmospheric aerosol number concentrations. The initial step of NPF includes the formation and growth of small clusters, their evaporation and loss to pre-existing particles (characterized by the condensation sink, CS). In the polluted atmospheric boundary layer, the high environmental CS suppresses NPF and it can work synergistically with evaporation to further reduce the NPF rates. In this study, to quantitatively include CS into NPF analysis, we make simplifications to the cluster balance equations and develop approximate equations for the NPF rates in the presence of pre-existing particles, which are applicable to nucleation mechanisms that can be represented by a nonbranched nucleation pathway. The developed equations show that the proportion of clusters that finally lead to new particle formation is given by the cluster-specific ratio of growth rate/CS | evaporation rate | growth rate. As a result, the cumulative product of this ratio for all clusters in the nucleation pathway determines the NPF rates. By comparing with benchmark cluster dynamics simulations of sulfuric acid-dimethylamine and sulfuric acid-ammonia nucleation systems, the developed equations were confirmed to give good estimates of the NPF rates and approximately capture the dependency of NPF rates on CS and nucleating vapor concentrations. The CS dependency predicted by the developed equations shows larger deviations from the simulations when the cluster evaporation rates are high, i.e., when the underlying assumptions of the equations are not satisfied. The equations were also found to be in good agreement with atmospheric NPF rates measured in long-term field observations in urban Beijing.Peer reviewe

The effect of dietary supplementation with Clostridium butyricum on the growth performance, immunity, intestinal microbiota and disease resistance of tilapia (Oreochromis niloticus).

This study was conducted to assess the effects of dietary Clostridium butyricum on the growth, immunity, intestinal microbiota and disease resistance of tilapia (Oreochromis niloticus). Three hundreds of tilapia (56.21 ± 0.81 g) were divided into 5 groups and fed a diet supplemented with C. butyricum at 0, 1 x 104, 1 x 105, 1 x 106 or 1 x 107 CFU g-1 diet (denoted as CG, CB1, CB2, CB3 and CB4, respectively) for 56 days. Then 45 fish from each group were intraperitoneally injected with Streptococcus agalactiae, and the mortality was recorded for 14 days. The results showed that dietary C. butyricum significantly improved the specific growth rate (SGR) and feed intake in the CB2 group and decreased the cumulative mortality post-challenge with S. agalactiae in the CB2, CB3 and CB4 groups. The serum total antioxidant capacity and intestinal interleukin receptor-associated kinase-4 gene expression were significantly increased, and serum malondialdehyde content and diamine oxidase activity were significantly decreased in the CB1, CB2, CB3 and CB4 groups. Serum complement 3 and complement 4 concentrations and intestinal gene expression of tumour necrosis factor α, interleukin 8, and myeloid differentiation factor 88 were significantly higher in the CB2, CB3 and CB4 groups. Intestinal toll-like receptor 2 gene expression was significantly upregulated in the CB3 and CB4 groups. Dietary C. butyricum increased the diversity of the intestinal microbiota and the relative abundance of beneficial bacteria (such as Bacillus), and decreased the relative abundance of opportunistic pathogenic bacteria (such as Aeromonas) in the CB2 group. These results revealed that dietary C. butyricum at a suitable dose enhanced growth performance, elevated humoral and intestinal immunity, regulated the intestinal microbial components, and improved disease resistance in tilapia. The optimal dose was 1 x 105 CFU g-1 diet

Chemical genomic analysis of GPR35 signaling

GPR35, a family A orphan G protein-coupled receptor, has been implicated in inflammatory, neurological, and cardiovascular diseases. However, not much is known about the signaling and functions of GPR35. We performed a label-free kinome short hairpin RNA screen and identified a putative signaling network of GPR35 in HT-29 cells, some of which was validated using gene expression, biochemical and cellular assays. The results showed that GPR35 induced hypoxia-inducible factor 1 alpha, and was involved in synaptic transmission, sensory perception, the immune system, and morphogenetic processes. Collectively, our data suggest that GPR35 may play an important role in response to hypoxic stress and be a potential target for the treatment of inflammatory, cardiovascular, and neurological disorders

Optimization of Saccharomyces boulardii production in solid-state fermentation with response surface methodology

Saccharomyces boulardii preparations are promising probiotics and clinical agents for animals and humans. This work focused on optimizing the nutritional conditions for the production of S. boulardii in solid-state fermentation by using classical and statistical methods. In single-factor experiments, the S. boulardii production was significantly increased by the addition of glucoamylase and the optimal carbon and nitrogen sources were found to be soluble starch and NH4Cl, respectively. The effects of the glucoamylase, soluble starch and NH4Cl on S. boulardii production were evaluated by a three-level three-factor Box–Behnken design and response surface methodology (RSM). The maximal yeast count (4.50 ×109CFU/g) was obtained under the optimized conditions (198 U/g glucoamylase, 2.37% soluble starch and 0.9% NH4Cl), which was in a good agreement with the predicted value of the model. This study has provided useful information on how to improve the accumulation of yeast cells by RSM

Discovery of Natural Phenols as G Protein-Coupled Receptor-35 (GPR35) Agonists

We report the discovery and characterization of natural phenols as G protein-coupled receptor-35 (GPR35) agonists. Pharmacological characterization using label-free dynamic mass redistribution and Tango β-arrestin translocation assays revealed that GPR35-active natural phenols are divergent in their biased agonism