212 research outputs found
New reactions and strategies in divergent syntheses of macrolide antibiotics
No full textFrom the microbial world, antibiotics are structurally complex and highly potent chemical weapons that co-evolved with bacteria. Macrolide (glycosylated cyclic polyketides) antibiotics have been used extensively as first-line antibacterial agents since the discovery of the broad-spectrum antibiotic erythromycin A in 1952. However wide-spread use of antibiotics has led pathogens to develop drug resistance. Therefore new and enhanced antibiotics are constantly in need. Described in this dissertation is my effort to emulate the synthetic capabilities of erythromycin-producing bacteria by accessing novel erythromycin-inspired polyketides via divergent total synthesis. New allene oxidation methods have been developed and implemented in a modular and divergent route to produce a diversified portfolio of cyclic polyketides and their glycoconjugates. I will disclose a total synthesis of 4,10-didesmethyl-(9S)-dihydroerythronolide A (Chapter 2), preparation of glycosylated erythromycin analogs (Chapter 3) and progress towards synthesis of 9(S)-dihydroerythronolide A (Chapter 4).Ph.D.Includes bibliographical referencesby Libing Y
Influenza Epidemic Trend Surveillance and Prediction Based on Search Engine Data: Deep Learning Model Study
No full textBackground: influenza outbreaks pose a significant threat to global public health. Traditional surveillance systems and simple algorithms often struggle to predict influenza outbreaks in an accurate and timely manner. Big data and modern technology have offered new modalities for disease surveillance and prediction. Influenza-like illness can serve as a valuable surveillance tool for emerging respiratory infectious diseases like influenza and COVID-19, especially when reported case data may not fully reflect the actual epidemic curve.Objective: this study aimed to develop a predictive model for influenza outbreaks by combining Baidu search query data with traditional virological surveillance data. The goal was to improve early detection and preparedness for influenza outbreaks in both northern and southern China, providing evidence for supplementing modern intelligence epidemic surveillance methods.Methods: we collected virological data from the National Influenza Surveillance Network and Baidu search query data from January 2011 to July 2018, totaling 3,691,865 and 1,563,361 respective samples. Relevant search terms related to influenza were identified and analyzed for their correlation with influenza-positive rates using Pearson correlation analysis. A distributed lag nonlinear model was used to assess the lag correlation of the search terms with influenza activity. Subsequently, a predictive model based on the gated recurrent unit and multiple attention mechanisms was developed to forecast the influenza-positive trend.Results: this study revealed a high correlation between specific Baidu search terms and influenza-positive rates in both northern and southern China, except for 1 term. The search terms were categorized into 4 groups: essential facts on influenza, influenza symptoms, influenza treatment and medicine, and influenza prevention, all of which showed correlation with the influenza-positive rate. The influenza prevention and influenza symptom groups had a lag correlation of 1.4-3.2 and 5.0-8.0 days, respectively. The Baidu search terms could help predict the influenza-positive rate 14-22 days in advance in southern China but interfered with influenza surveillance in northern China.Conclusions: complementing traditional disease surveillance systems with information from web-based data sources can aid in detecting warning signs of influenza outbreaks earlier. However, supplementation of modern surveillance with search engine information should be approached cautiously. This approach provides valuable insights for digital epidemiology and has the potential for broader application in respiratory infectious disease surveillance. Further research should explore the optimization and customization of search terms for different regions and languages to improve the accuracy of influenza prediction models.</p
Research on the relationship between the elements and pharmacological activities in velvet antler using factor analysis and cluster analysis
No full textGeochemical studies on Permian manganese deposits in Guichi, eastern China: Implications for their origin and formative environments
No full textPermian manganese ore deposits are widely distributed in southwestern and eastern China. Guichi Permian manganese district in southern Anhui Province, central eastern China, is currently the most important manganese metal producers in eastern China. Manganese ores (MnO = 18.2-45.4 wt.%) in Guichi region occur in calcareous, argillaceous and siliceous Mn-bearing sequence of the Permian Gufeng Formation. In contrast to Mn-bearing rocks, the ores have higher Mn, Fe, P, Sr (more than 1500 ppm) and Ni contents (>480 ppm), higher Mn/Fe (>5) and La-n/Ce-n (>2) values, and lower Co/Ni (<0.05) ratios. The Guichi manganese deposits also have low Co/Ni (<1) and Co/Zn ratios, low in total REE contents (mostly < 100 ppm) with negative Eu (0.46-0.75) and Ce (0.42-0.76) anomalies. The mineralogy and geochemistry of manganese deposits in the Guichi region strongly indicate hydrothermal activities, which is supported by high paleotemperatures (49-71 degrees C) of Permian Mn-carbonate ore and Mn-bearing carbonate. The low Ce-anom. values (<-0.1) and high strontium contents indicate that the Guichi manganese deposits were formed in high-salinity and oxidative marine sedimentary environment. The Al2O3/TiO2 (9.23-48.2) and Y/Ho (25.9-44.4) ratios, REE patterns, delta C-13(V-PDB) (-10.2 parts per thousand to 5.00 parts per thousand) and delta O-18(SMOW) (20.7-28.0 parts per thousand characteristics of Permian manganese deposits reveal a mixed Mn source of volcanic, terrigenous and organic matter. (C) 2013 Elsevier Ltd. All rights reserved
Adaptive filter using decision-feedback to suppress BPSK interference in spread spectrum systems
No full text
Systematic Thinking of Human Intelligence
No full textThis paper expounds the great significance of human intelligence research from the height of the wisdom age. We should understand what it is to be a human being and what are the mechanisms of this intelligence. The author advocates that systematic science should be involved in such research. Methodology, especially oriental holistic thinking, is important. We put out the idea of “Education Engineer”, first try to do theoretical research, focus a concept System Quotient, then to build a model. To establish such a system, we undertake several decades of exploration according to the thought of Xuesen Qian’s “Dacheng Wisdom” and the fruits of information science and intelligence science. The concepts of “Human intelligence system” and “System Quotient ”(SQ) are proposed, developed completely and applied in the classroom. A “teaching information feedback system” has been created. It contains a “classroom informatization” and a “Playing with Science” system
ON GEODESICS OF FINSLER METRICS VIA NAVIGATION PROBLEM
No full textThis paper is devoted to a study of geodesics of Finsler metrics via Zermelo navigation. We give a geometric description of the geodesics of the Finsler metric produced from any Finsler metric and any homothetic field in terms of navigation representation, generalizing a result previously only known in the case of Randers metrics with constant S-curvature. As its application, we present explicitly the geodesics of the Funk metric on a strongly convex domain.Mathematics, AppliedMathematicsSCI(E)0ARTICLE83015-302413
On Finsler surfaces of constant curvature with two-dimensional isometry group
No full textIn this paper, we study Finsler surfaces of constant (flag) curvature. We show that the space of those, with two-dimensional isometric group depends on two arbitrary constants. We also give a new technique to recover Finsler metrics from the specified two constants. Using this technique we obtain some new Finsler surfaces of constant flag curvature with two-dimensional isometry group.National Natural Science Foundation of China [11371032, 11301283]SCI(E)[email protected]; [email protected]
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