31 research outputs found
A necessary and sufficient condition for lower bounds on crossing numbers of generalized periodic graphs in an arbitrary surface
Full text linkLet , and be a graph, a tree and a cycle of order ,
respectively. Let be the complete join of and an empty graph on
vertices. Then the Cartesian product of and can be
obtained by applying zip product on and the graph produced by zip
product repeatedly. Let denote the crossing number of
in an arbitrary surface . If satisfies certain connectivity
condition, then is not less than the sum of the
crossing numbers of its ``subgraphs". In this paper, we introduced a new
concept of generalized periodic graphs, which contains . For a
generalized periodic graph and a function , where is the number
of subgraphs in a decomposition of , we gave a necessary and sufficient
condition for . As an application, we
confirmed a conjecture of Lin et al. on the crossing number of the generalized
Petersen graph in the plane. Based on the condition, algorithms
are constructed to compute lower bounds on the crossing number of generalized
periodic graphs in . In special cases, it is possible to determine
lower bounds on an infinite family of generalized periodic graphs, by
determining a lower bound on the crossing number of a finite generalized
periodic graph.Comment: 26 pages, 20 figure
Application Potential of Constructed Wetlands on Different Operation Mode for Biologically Pre-Treatment of Rural Domestic Wastewater
No full textIn order to satisfy the requirements of rural domestic sewage, a bio-ecological combination system was proposed, including a biological treatment section (anaerobic hydrolysis tank and aerobic tank) and an ecological post-treatment section. This study observed the application potential of constructed wetlands (CW) on different operation modes for biologically pre-treated rural domestic wastewater. The organics and nutrient removal efficiency of the tidal flow constructed wetland (TFCW) and the horizontal subsurface flow constructed wetland (HFCW) were compared at a temperature range of 20–40 °C. During the stable phase, the higher chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), and total phosphorus (TP) removal efficiencies existed in TFCW than HFCW, corresponding to the efficiency of COD 69.46%, NH4+-N 96.47%, and TP 57.38%, but lower performance on COD (61.43%), NH4+-N (84.99%), and TP (46.75%) removal in HFCW, which should be attributed to the increasement of aerobic heterotrophic bacteria (Arthrobact and Sphingomonas), nitrifiers (Nitrospira), and phosphate accumulating organisms (PAOs) (Pseudomonas). The microbial biomass was also increased from 2.13 ± 0.14 mg/g (HFCW) to 4.64 ± 0.18 mg/g (TFCW), which proved to strengthen the formation and growth of biofilm under a better oxygen supplement. Based on the relative abundance of functional genera in the microbial community, it showed that TFCW was more favorable for promoting the growth of heterotrophic bacteria, nitrifiers, and phosphate-accumulating organisms (PAOs). When temperature changed from −4 °C to 15 °C, the two-stage constructed wetlands (TFCW-HFCW and HFCW-TFCW) were used for improving the performance of pollutants removal. The results demonstrated that the effluent concentrations of TFCW-HFCW and HFCW-TFCW met the Class 1A discharge standard of DB32/3462-2020 in JiangSu Province, China. Therefore, this study will provide a useful and easy-to-implement technology for the operation as an ecological post-treatment section
Effects of Carbon Source on Denitrification and Electricity Generation in Composite Packing MFC-CW for Tail Water Treatment
No full textThe tail wastewater from sewage treatment facilities usually lacks carbon sources, and its subsequent treatment for deep nitrogen removal is difficult in natural conditions. In this study, the constructed wetland (CW) was integrated with microbial fuel cell (MFC) with high-density polyethylene (HDPE) fillers as the main matrix to improve nitrogen removal under inefficient carbon source conditions. Compared with the regular MFC and CW systems, MFC-CW attained higher nitrogen removal under low-carbon source conditions. The influence of influent carbon/nitrogen ratio (C/N) on the denitrification and electricity-generation performance was explored. Although the increase of carbon source simultaneously improved chemical oxygen demand (COD), ammonia (NH4+-N), nitrate (NO3−-N) and TN removal, the power generation during the carbon source adjustment showed low relation with the variation of influent COD in the range of 40–120 mg/L. CW was more dependent on carbon sources, and the addition of bioelectrochemical systems into MFC-CW could reduce the dependence of nitrogen removal on carbon sources, especially under low carbon source conditions. These findings offer valuable insights into the potential applications of MFC-CW for tail water treatment, and its parameters for utilization in real CWs should be explored in future studies
A palladium-catalyzed intramolecular carbonylative annulation reaction for the synthesis of 4,5-fused tricyclic 2-quinolones
No full textA concise and efficient synthetic route to 4,5-fused tricyclic 2-quinolones through the palladium-catalyzed carbonylative annulation of alkyne-tethered N-substituted o-iodoanilines has been developed. This reaction proceeds smoothly under mild reaction conditions and exhibits exceptional tolerance to a variety of functional groups. It has been successfully applied to the efficient synthesis of BI 224436, an HIV integrase inhibitor.National Natural Science Foundation of China [21372017, 21290183, 21572008]SCI(E)[email protected]
Total Syntheses of Festuclavine, Pyroclavine, Costaclavine, epi-Costaclavine, Pibocin A, 9-Deacetoxyfumigaclavine C, Fumigaclavine G, and Dihydrosetoclavine
No full textA new approach for the divergent total synthesis of eight ergot alkaloids is reported. The approach allows the first total syntheses of pyroclavine, pibocin A, 9-deacetoxyfumigaclavine C, and fumigaclavine G and also enables the efficient synthesis of festuclavine, costaclavine, epi-costaclavine, and dihydrosetoclavine. The main feature of the synthesis is the use of an unprecedented Pd-catalyzed intramolecular Larock indole annulation/TsujiTrost allylation cascade to assemble the tetracyclic core in one step.National Natural Science Foundation of China [21372017, 21402003, 21290183, 21572008]; State Key Laboratory of Drug ResearchSCI(E)ARTICLE123323-33261
Treatment Performance and Characteristics of Biofilm Carriers in an Aerobic Waterwheel-Driven Rotating Biological Contactor
No full textRotating biological contactors (RBCs) are widely utilized in aerobic wastewater treatment due to their high stability, efficiency, and ease of maintenance. The choice of disc carrier material for biofilm formation is a critical factor influencing treatment performance. In the context of rural domestic wastewater treatment, the biofilm carriers must balance cost-effectiveness and high efficiency. This study focuses on the aerobic unit of a combined anoxic denitrification–deodorization filter–aerobic RBC system, specifically, the waterwheel-driven aerobic RBC, and evaluates three types of biofilm carrier media: felt, carbon felt, and nonwoven fabric. The study compares their pollutant removal performance and biofilm enrichment characteristics to identify the optimal material. The results indicate that RBCs using nonwoven fabric as the biofilm carrier exhibit superior nitrification efficiency and biocompatibility compared to the other materials, achieving average removal rates of 84.3% for CODCr and 80.5% for ammonia nitrogen. While the addition of nonwoven fabric slightly reduced the driving efficiency of the waterwheel-driven aerobic RBC, it significantly enhanced oxygen transfer efficiency, which explained the enhanced organic degradation and ammonia nitrification. During the biofilm stable phase, the two-stage waterwheel-driven RBC with a nonwoven fabric carrier achieved average CODCr and ammonia nitrogen removal rates of 86.76 ± 0.85% and 92.15 ± 1.49%, respectively. Nonwoven fabric demonstrates significant potential as a biofilm carrier for aerobic rotating biological contactors
Correlation Analysis of 3D Printability and Rheological Properties of Sodium Alginate Hydrogels
Full text linkIn this study, Ca2+-induced sodium alginate hydrogel was used as a model. The rheological properties were measured via steady-state shear, oscillation strain sweep, and yield stress. The network of sodium alginate hydrogels was analyzed using water distribution and rheological parameters. After a comprehensive analysis of the morphology and Micro-CT structure of 3D printing products, the mathematical relationship between rheological parameters and 3D printing effect was established using the Spearman's correlation analysis. The results showed that the highest score of 3D printing product was prepared at the mass ratio of SA to Ca2+ at 24:1 and the concentration of SA at 4.5%. At the same time, the filament structure of 3D printing product was fine and the porosity was 12.21%. Rheological parameters of K, η1, G', G", τ0 and τy were 255.1 Pa·sn, 2740 Pa·s, 3509 Pa, 673.2 Pa, 261.4 Pa, and 51.62 Pa, respectively. The capillary water (about 99.20%) was dominant in the gel network, showing strong water holding capacity of hydrogel. Results of correlation analysis showed that the viscosity properties (K, η1, and G") were negatively correlated with the extrudability, and the correlation coefficient was -0.577. The self-supporting capacity of the 3D printing product was positively correlated with the elastic modulus and stress (G', τ0, and τy) (P<0.05)
Predicting breast cancer chemotherapeutic response using a novel tool for microarray data analysis
No full textSummary We developed a novel tool for microarray data analysis that can parsimoniously discover highly predictive genes by finding the optimal trade off between fold change and t-test p value through rigorous cross validation. In addition to find a small set of highly predictive genes, the tool also has a procedure that recursively discovers and removes predictive genes from the dataset until no such genes can be found. We applied our tool to a public breast cancer dataset with the goal to discover genes that can predict patient’s response to a preoperative chemotherapy. The results show that estrogen receptor (ER) gene is the most important gene to predict chemotherapeutic response and no gene signatures can add much clinical benefit for the whole patient population. We further identified a clinically homogenous subgroup of patients (ER-negative, PR-negative and HER2-negative) whose response to the chemotherapy can be reasonably predicted. Many of the discovered predictive markers for this subgroup of patients were successfully validated using a blinded validation set.</jats:p
Predicting breast cancer chemotherapeutic response using a novel tool for microarray data analysis
No full textWe developed a novel tool for microarray data analysis that can parsimoniously discover highly predictive genes by finding the optimal trade off between fold change and t-test p value through rigorous cross validation. In addition to find a small set of highly predictive genes, the tool also has a procedure that recursively discovers and removes predictive genes from the dataset until no such genes can be found. We applied our tool to a public breast cancer dataset with the goal to discover genes that can predict patient’s response to a preoperative chemotherapy. The results show that estrogen receptor (ER) gene is the most important gene to predict chemotherapeutic response and no gene signatures can add much clinical benefit for the whole patient population. We further identified a clinically homogenous subgroup of patients (ER-negative, PR-negative and HER2-negative) whose response to the chemotherapy can be reasonably predicted. Many of the discovered predictive markers for this subgroup of patients were successfully validated using a blinded validation set
