Quantum Chemistry Modeling of Homogeneous First-Row Transition Metal Catalysis

Catalysts accelerate rates of chemical reactions, and there is great interest in identifying catalysts that are effective, stable, and economical. This thesis reports two homogeneous chemical reaction mechanism studies using first principles quantum chemistry. The goal of this work is to understand the fundamental reaction pathways that reactions occur, so that one might eventually make improved catalysts. A cobalt-based catalyst system was recently reported for CO2 hydrogenation to form formate.1 It was hypothesized that a cooperative bifunctional catalyst involving an N-heterocyclic carbene (NHC) and this cobalt-based catalyst might further improve this chemistry. We investigated the likelihood that the NHC could function either as a Brønsted base to deprotonate a metal hydride or dihydrogen intermediate, or as a Lewis base to activate carbon dioxide towards nucleophilic attack. We also investigated fundamental catalysis involving heterobimetallic catalysts. We elucidated a complete mechanistic pathway for C−H boralytion with Cu−Fe catalysts to explain experimental observations and suggest improvements to the catalyst. This thesis aims to provide useful insight into canonical organometallic reaction mechanisms involved in bimetallic catalysts

Development of village doctors in China: financial compensation and health system support.

BACKGROUND: Since 1968, China has trained about 1.5 million barefoot doctors in a few years' time to provide basic health services to 0.8 billion rural population. China's Ministry of Health stopped using the term of barefoot doctor in 1985, and changed policy to develop village doctors. Since then, village doctors have kept on playing an irreplaceable role in China's rural health, even though the number of village doctors has fluctuated over the years and they face serious challenges. United Nations declared Sustainable Development Goals in 2015 to achieve universal health coverage by 2030. Under this context, development of Community Health workers (CHWs) has become an emerging policy priority in many resource-poor developing countries. China's experiences and lessons learnt in developing and maintaining village doctors may be useful for these developing countries. METHODS: This paper aims to synthesis lessons learnt from the Chinese CHW experiences. It summarizes China's experiences in exploring and using strategic partnership between the community and the formal health system to develop CHWs in the two stages, the barefoot doctor stage (1968 -1985) and the village doctor stage (1985-now). Chinese and English literature were searched from PubMed, CNKI and Wanfang. The information extracted from the selected articles were synthesized according to the four partnership strategies for communities and health system to support CHW development, namely 1) joint ownership and design of CHW programmes; 2) collaborative supervision and constructive feedback; 3) a balanced package of incentives, both financial and non-financial; and 4) a practical monitoring system incorporating data from the health system and community. RESULTS: The study found that the townships and villages provided an institutional basis for barefoot doctor policy, while the formal health system, including urban hospitals, county health schools, township health centers, and mobile medical teams provided training to the barefoot doctors. But After 1985, the formal health system played a more dominant role in the CHW system including both selection and training of village doctors. China applied various mechanisms to compensate village doctors in different stages. During 1960s and 1970s, the main income source of barefoot doctors was from their villages' collective economy. After 1985 when the rural collective economy collapsed and barefoot doctors were transformed to village doctors, they depended on user fees, especially from drug sale revenues. In the new century, especially after the new round of health system reform in 2009, government subsidy has become an increasing source of village doctors' income. CONCLUSION: The barefoot doctor policy has played a significant role in providing basic human resources for health and basic health services to rural populations when rural area had great shortages of health resources. The key experiences for this great achievement are the intersection between the community and the formal health system, and sustained and stable financial compensation to the community health workers

Genetic architecture of lodging resistance revealed by genome- wide association study in maize (Zea mays L)

Lodging is one of key factors influencing biomass yield, restricting planting density and reducing mechanical harvesting productivity in maize. Targeted cultivating lodging resistance varieties with screened lines is an eco- nomical and effective approach to improve ability of maize lodging resistance. To accomplish this objective, we performed phenotypic assessment of seven lodging-related traits in a diverse maize population consisting of 290 inbred lines and conducted a genome-wide association study with 201 SSR markers to detected marker-trait as- sociations. Seven lodging-related traits all showed broad phenotypic variations. Through evaluation of stalk push- ing resistance in the field for two years, a number of 32 inbred lines featured with strong lodging resistance were selected out. Correlation analysis indicated that stalk pushing resistance had a significantly positive correlation with third internode diameter and fourth internode diameter and a significantly negative correlation with ear height. Furthermore, a total of 27 and 13 significant associations for lodging-related traits were identified in year 2012 and 2013, respectively. Interestingly, three associations on chromosome 4, 5, and 6 were discovered in both years. Thus, this study provides useful information for understanding genetic architecture of lodging resistance in maize and will benefit maize marker-assistant breeding program with improving lodging resistance

Sparse-TFM Imaging of Lamb Waves for the Near-Distance Defects in Plate-Like Structures

The ultrasonic phased array total focusing method (TFM) has the advantages of high imaging resolution and high sensitivity to small defects. However, it has a long imaging time and cannot realize near-distance defect imaging, which limits its application for industrial detection. A sparse-TFM algorithm is adopted in this work to solve the problem regarding rapid imaging of near- distance defects in thin plates. Green’s function is reconstructed through the cross-correlation of the diffuse full matrix captured by the ultrasonic phased array. The reconstructed full matrix recovers near-distance scattering information submerged by noise. A sparse array is applied to TFM for rapid imaging. In order to improve the imaging resolution, the location of active array elements in the sparse array can be optimized using the genetic algorithm (GA). Experiments are conducted on three aluminium plates with near-distance defects. The experimental results confirm that the sparse-TFM algorithm of Lamb waves can be used for near-distance defects imaging, which increases the computational efficiency by keeping the imaging accuracy. This paper provides a theoretical guidance for Lamb wave non-destructive testing of the near-distance defects in plate-like structures

Comprehensive and integrative analysis identifies microRNA-106 as a novel non-invasive biomarker for detection of gastric cancer

Abstract Background Recently, accumulating evidences have revealed that microRNA-106 (miR-106) may serve as a non-invasive and cost-effective biomarker in gastric cancer (GC) detection. However, inconsistent results have prevented its application to clinical practice. Methods As a result of this, a comprehensive meta-analysis was conducted to evaluate the diagnostic performance of miR-106 alone and miR-106-related combination markers for GC detection. Meanwhile, an integrative bioinformatics analysis was performed to explore the function of miR-106 at the systems biology level. Results The results in our work showed that sensitivity of 0.71 (95% CI 0.65–0.76) and specificity of 0.82 (0.72–0.88), with the under area AUC (area under the curve) value of 0.80 (0.76–0.83) for miR-106 alone. Prospectively, miR-106-related combination markers improved the combined sensitivity, specificity and AUC, describing the discriminatory ability of 0.78 (0.65–0.87), 0.83 (0.77–0.89) and 0.88 (0.85–0.90) in the present analysis. Furthermore, targets of miR-106 were obtained and enriched by gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis, revealing their associations with the occurrence and development of GC. Hub genes and significant modules were identified from the protein–protein interaction networks constructed by miR-106 targets and found closely associated with the initiation and progression of GC again. Conclusions Our comprehensive and integrative analysis revealed that miR-106 may be suitable as a diagnostic biomarker for GC while microRNA combination biomarkers may provide a new alternative for clinical application. However, it is necessary to conduct large-scale population-based studies and biological experiments to further investigate the diagnostic value of miR-106

Impact of particle density on the classification efficiency of the static air classifier in Vertical Spindle Mill

In order to investigate the impact of density on the classification behavior of particles in the static classifier of Vertical Spindle Mill, the sensitivity of overflow yield to the increase of air amount for narrowly sized pyrite, carborundum, quartz and coal samples were compared in a lab-scale classifier, respectively. Response surface methodology is used to analyze the combined effect of size and density on the classification. Wide size classification was also conducted and results show that both the yield and R90 of overflow increase with the decreasing of density, and the growth of air amount would also lead them to rise. The Whiten’s model was applied to illustrate the influence of density on the sharpness of classification, corrected cut size and fishhook effect. Results show that material with a lower density would have a higher fishhook effect parameter, classification sharpness and corrected cut size. The increase of air amount would result in a more evident fishhook effect for the high density material. Based on the Whiten’s model, a new classification efficiency model with the addition of particle density in various forms was established. This new model could describe the classification efficiency of materials with different density in the identical experiment conditions

Genome-Wide Analysis of Sugar Transporters Identifies the gtsA Gene for Glucose Transportation in Pseudomonas stutzeri A1501

Pseudomonas stutzeri A1501 possesses an extraordinary number of transporters which confer this rhizosphere bacterium with the sophisticated ability to metabolize various carbon sources. However, sugars are not a preferred carbon source for P. stutzeri A1501. The P. stutzeri A1501 genome has been sequenced, allowing for the homology-based in silico identification of genes potentially encoding sugar-transport systems by using established microbial sugar transporters as a template sequence. Genomic analysis revealed that there were 10 sugar transporters in P. stutzeri A1501, most of which belong to the ATP-binding cassette (ABC) family (5/10); the others belong to the phosphotransferase system (PTS), major intrinsic protein (MIP) family, major facilitator superfamily (MFS) and the sodium solute superfamily (SSS). These systems might serve for the import of glucose, galactose, fructose and other types of sugar. Growth analysis showed that the only effective medium was glucose and its corresponding metabolic system was relatively complete. Notably, the loci of glucose metabolism regulatory systems HexR, GltR/GtrS, and GntR were adjacent to the transporters ABCMalEFGK, ABCGtsABCD, and ABCMtlEFGK, respectively. Only the ABCGtsABCD expression was significantly upregulated under both glucose-sufficient and -limited conditions. The predicted structure and mutant phenotype data of the key protein GtsA provided biochemical evidence that P. stutzeri A1501 predominantly utilized the ABCGtsABCD transporter for glucose uptake. We speculate that gene absence and gene diversity in P. stutzeri A1501 was caused by sugar-deficient environmental factors and hope that this report can provide guidance for further analysis of similar bacterial lifestyles