Development of New Homogeneous (Enantioselective): Hydrogenation Catalysts Based on Bio‐relevant Metals

This thesis presents the study and development of new catalysts based on first row transition metals for the (asymmetric) reduction of different C=O and C=N bonds. An iron cluster catalyst with a chiral tetradentate P2N2 ligand was discovered to catalyze the asymmetric transfer hydrogenation of N-diphenylphosphinylketimines. Subsequently the combination of a chiral Brønsted acid with a well-defined Shvo type iron complex creates an active catalyst which could hydrogenate a variety of N-aryl ketimines to amines using molecular hydrogen. Finally, an iron cluster catalyst was discovered to catalyze the reduction of amides with inexpensive PMHS

Prevalence, risk factors, outcomes, and molecular epidemiology of mcr-1 -positive Enterobacteriaceae in patients and healthy adults from China: an epidemiological and clinical study

Background The mcr-1 gene confers transferable colistin resistance. mcr-1-positive Enterobacteriaceae (MCRPE) have attracted substantial medical, media, and political attention; however, so far studies have not addressed their clinical impact. Herein, we report the prevalence of MCRPE in human infections and carriage, clinical associations of mcr-1-positive Escherichia coli (MCRPEC) infection, and risk factors for MCRPEC carriage. Methods We undertook this study at two hospitals in Zhejiang and Guangdong, China. We did a retrospective cross-sectional assessment of prevalence of MCRPE infection from isolates of Gram-negative bacteria collected at the hospitals from 2007 to 2015 (prevalence study). We did a retrospective case-control study of risk factors for infection and mortality after infection, using all MCRPEC from infection isolates and a random sample of mcr-1-negative E coli infections from the retrospective collection between 2012 and 2015 (infection study). We also did a prospective case-control study to assess risk factors for carriage of MCRPEC in rectal swabs from inpatients with MCRPEC and mcr-1 negative at the hospitals and collected between May and December, 2015, compared with mcr-1-negative isolates from rectal swabs of inpatients (colonisation study). Strains were analysed for antibiotic resistance, plasmid typing, and transfer analysis, and strain relatedness. Findings We identified 21 621 non-duplicate isolates of Enterobacteriaceae, Acinetobacter spp, and Pseudomonas aeruginosa from 18 698 inpatients and 2923 healthy volunteers. Of 17 498 isolates associated with infection, mcr-1 was detected in 76 (1%) of 5332 E coli isolates, 13 (<1%) of 348 Klebsiella pneumoniae, one (<1%) of 890 Enterobacter cloacae, and one (1%) of 162 Enterobacter aerogenes. For the infection study, we included 76 mcr-1-positive clinical E coli isolates and 508 mcr-1-negative isolates. Overall, MCRPEC infection was associated with male sex (209 [41%] vs 47 [63%], adjusted p=0·011), immunosuppression (30 [6%] vs 11 [15%], adjusted p=0·011), and antibiotic use, particularly carbapenems (45 [9%] vs 18 [24%], adjusted p=0·002) and fluoroquinolones (95 [19%] vs 23 [30%], adjusted p=0·017), before hospital admission. For the colonisation study, we screened 2923 rectal swabs from healthy volunteers, of which 19 were MCRPEC, and 1200 rectal swabs from patients, of which 35 were MCRPEC. Antibiotic use before hospital admission (p<0·0001) was associated with MCRPEC carriage in 35 patients compared with 378 patients with mcr-1-negative E coli colonisation, whereas living next to a farm was associated with mcr-1-negative E coli colonisation (p=0·03, univariate test). mcr-1 could be transferred between bacteria at high frequencies (10−1 to 10−3), and plasmid types and MCRPEC multi-locus sequence types (MLSTs) were more variable in Guangdong than in Zhejiang and included the human pathogen ST131. MCRPEC also included 17 unreported ST clades. Interpretation In 2017, colistin will be formally banned from animal feeds in China and switched to human therapy. Infection with MRCPEC is associated with sex, immunosuppression, and previous antibiotic exposure, while colonisation is also associated with antibiotic exposure. MLST and plasmid analysis shows that MCRPEC are diversely spread throughout China and pervasive in Chinese communities

Process Simulation and Optimization of Fluid Catalytic Cracking Unit’s Rich Gas Compression System and Absorption Stabilization System

In a fuel-based refinery, rich gas in the fluid catalytic cracking (FCC) unit is further processed to separate dry gas and refinery products (i.e., stabilized gasoline and liquified petroleum gas). The process is utility-intensive and costly and includes a two-stage compressor, pumps, an absorber, a stripper, a stabilizer, and a re-absorber. The optimization was conducted with respect to the compressor outlet pressure from the gas compression system (GCS) and the flow rate of absorbent and supplementary absorbent from the Absorption-stabilization System (ASS) using the process simulation software Aspen Plus. Compared to the base case of a 725 kt/a rich gas FCC unit, a refinery can save 2.42% of utility costs under optimal operation. Through optimized operation, medium-pressure steam consumption has been reduced by 2.4% compared to the base case, resulting in a significant improvement in total operational cost. The optimization strategy can provide insightful guidance for the practical operation of GCS and ASS.</p

The role of functional strategies in global plant distribution

© 2020 The Authors. Ecography published by John Wiley & Sons Ltd on behalf of Nordic Society Oikos Understanding the determinants of species distributions is a central topic in ecology. Competition, stress tolerance and colonization, respectively represented by Grime\u27s competitor (C), stress-tolerator (S) and ruderal (R) schemes, are three important functions that interactively influence plant distributions. In this study, we compiled a dataset of 2645 vascular plant species to explore the roles of the CSR strategies in global plant distribution. We analyzed the associations between the CSR scores and species range size with phylogenetic generalized least square (PGLS) models and phylogenetic path analysis, both of which accounted for the effects of species phylogenetic relatedness, longevity and growth form. The functional strategy-range size associations differed across different distributional ranges and growth forms. Specifically, species global and native range sizes were positively associated with the R score; species naturalized range size was positively associated with the C score; and all range-size measurements were negatively associated with the S score. These patterns were mostly driven by herbs but not shrubs or trees. For species global and native-range distributions, the patterns of shrubs were even opposite to those of herbs. Our work emphasizes the importance of distinguishing the functional strategy-distribution associations between different distributional ranges and growth forms for ecosystem conservation and invasion risk prediction, because of the trade-offs among the CSR strategies

Exploring the causal role of plasma metabolites and metabolite ratios in prostate cancer: a two-sample Mendelian randomization study

BackgroundProstate cancer (PCa), the most prevalent malignant neoplasm in males, involves complex biological mechanisms and risk factors, many of which remain unidentified. By employing a novel two-sample Mendelian randomization (MR) approach, this study aims to elucidate the causal relationships between the circulating metabolome and PCa risk, utilizing comprehensive data on genetically determined plasma metabolites and metabolite ratios.MethodsFor the MR analysis, we utilized data from the GWAS Catalog database to analyze 1,091 plasma metabolites and 309 ratios in relation to PCa outcomes within two independent GWAS datasets. The inverse variance weighted (IVW) method was the primary approach for determining the existence of the causal relationship, supplemented by additional MR methods for heterogeneity, pleiotropy, and cross-validation. The false discovery rate (FDR) and Bonferroni correction were applied to identify the most significant causative associations. Additionally, reverse MR and Steiger filtering were conducted to ascertain whether PCa influenced the observed metabolite levels. Furthermore, metabolic pathway analysis was conducted with MetaboAnalyst 6.0 software.ResultsIn the MR analysis, our findings reveal three overlapped metabolite ratios (arginine to glutamate, phosphate to uridine, and glycerol to mannitol/sorbitol) inversely associated with PCa risk. Following FDR correction (FDR &lt; 0.05), cysteinylglycine disulfide was identified as a potential reducer of PCa risk, whereas Uridine and N-acetyl-L-glutamine (NAG) were pinpointed as potential risk factors. Notably, NAG (OR 1.044; 95% CI 1.025–1.063) emerged as a metabolite with significant causal influence, as confirmed by stringent Bonferroni correction (P &lt; 0.05/1400). Steiger’s directionality test (P &lt; 0.001) and reverse MR confirmed the proposed causal direction. Furthermore, metabolic pathway analysis revealed a significant association between the “Glutathione Metabolism” pathway and PCa development.ConclusionThis study provides novel insights into the potential causal effects of plasma metabolites and metabolite ratios on PCa. The identified metabolites and ratios could serve as candidate biomarkers, contributing to the elucidation of PCa’s biological mechanisms