Diversification of 4-Alkylpyridines: Mining for Reactivity with Alkylidene Dihydropyridines

Pyridines are valued structures in pharmaceutical development. Using a soft enolization approach, we can diversify alkyl pyridines under mild conditions via alkylidene dihydropyridines (ADHPs). Recent work in our group has demonstrated the utility of ADHPs in palladium-catalyzed reactions. However, the fundamental reactivity of ADHPs remains largely unexplored, with only scattered reports in the literature. We seek to further explore the reactivity of these electron-rich intermediates in different contexts, as new transformations can provide useful synthetic tools for pharmaceutical discovery. Herein we describe our investigations in this area, including the development of two new synthetic methods. Specifically, we describe the oxidation of ADHPs to the corresponding pyridylic ketones under mild conditions, and the iridium-catalyzed asymmetric alkylation of alkylidene dihydropyridines branch-allylated alkyl pyridines

Economic load dispatch solutions considering multiple fuels for thermal units and generation cost of wind turbines

In this paper, economic load dispatch (ELD) problem is solved by applying a suggested improved particle swarm optimization (IPSO) for reaching the lowest total power generation cost from wind farms (WFs) and thermal units (TUs). The suggested IPSO is the modified version of Particle swarm optimization (PSO) by changing velocity and position updates. The five best solutions are employed to replace the so-far best position of each particle in velocity update mechanism and the five best solutions are used to replace previous position of each particle in position update. In addition, constriction factor is also used in the suggested IPSO. PSO, constriction factor-based PSO (CFPSO) and bat optimization algorithm (BOA) are also run for comparisons. Two systems are used to run the four methods. The first system is comprised of nine TUs with multiple fuels and one wind farm. The second system is comprised of eight TUs with multiple fuels and two WFs. From the comparisons of results, IPSO is much more powerful than three others and it can find optimal power generation with the lowest total power generation cost

Effect of some effective parameters on COD Removal from Nam Son Landfill Leachate by electrocoagulation

Leachate becomes ahead of wastewaters as being the most difficult to treat due to its complex and widely variable composition. In this research, the leachate treatment performance by electrocoagulation (EC) was studied. The samples of leachate were taken from Nam Son landfill in Hanoi. The effects of factors namely current intensity, electrolysis time, initial pH and anode materials on the EC performance were investigated via chemical oxygen demand (COD) removal efficiencies. The input leachate properties were obtained as COD, NH4+ and pH in the range of around 6247 ± 295, 1270 ± 38 mg/l and 8 ± 0.1, respectively. Mono-polar electrocoagulation unit was carried out in a batch system for leachate treatment with iron electrodes and approximately 1.8 litter of leachate. Firstly, with the increase in current (1 to 4A), the COD removal efficiencies increased from 50.00 to 78.57% (pH = 8 and operating time = 40 min). Secondly, by the increase in operating time, the treatment performance also went up significantly in first 40 min, then nearly level-off at above 73 % (pH=8, current intensity = 3A). In addition, the effect of pH in range of 5 to 10 on the electrocoagulation process was studied and showed the highest treatment efficiencies in neutral and mild alkaline medium, especially between 6 pH 8. Finally, the electrode materials made of iron and aluminum was investigated and the result indicated that when the iron anodes were replaced by aluminum, the COD removal efficiency experienced a considerable decline, from 70 to 37.93% (pH = 8 and operating time = 40 min). In combination of all experiments, the optimum operating conditions were achieved as iron electrodes, current intensity of 3A, electrolysis time of 40 min, the raw pH with iron electrodes, resulting the maximum COD removal efficiencies of 73.21%. As a result, the electrocoagulation can be applied to leachate pre-treatment

Global attractivity of positive periodic solution of a delayed Nicholson model with nonlinear density-dependent mortality term

This paper is concerned with the existence, uniqueness and global attractivity of positive periodic solution of a delayed Nicholson’s blowflies model with nonlinear density-dependent mortality rate. By some comparison techniques via differential inequalities, we first establish sufficient conditions for the global uniform permanence and dissipativity of the model. We then utilize an extended version of the Lyapunov functional method to show the existence and global attractivity of a unique positive periodic solution of the underlying model. An application to the model with constant coefficients is also presented. Two numerical examples with simulations are given to illustrate the efficacy of the obtained results

The application of (Y,Gd)BO3:Tb3+ and CaGa2S4:Mn2+ phosphors to remote white light-emitting diodes

The remote phosphor structure is superior to the conformal phosphor and the in-cup phosphor in terms of lighting efficiency; however, managing the color quality of the remote phosphor structure has been a nuisance to the manufacturers. To address this problem, many researches were conducted and the results suggested that using dual-layer phosphor structure and triple-layer phosphor structure could improve the color quality in remote phosphor structures. The purpose of this article is to study which one between the two configurations mentioned above allows multi-chip white LEDs (WLEDs) to reach highest indexes in color rendering index (CRI), color quality scale (CQS), luminous flux (LF), and color uniformity. The color temperature of the WLEDs used for the experiments in this article is 8500 K. The result of this research shows that the triple-layer phosphor configuration has higher CRI, CQS, and LE and also able to reduce color deviation resulting in better color uniformity. This conclusion can be verified by analyzing the scattering features of the phosphor layers using the Mie-theory. Being verifiable increases the reliability of the research result and makes it a valuable reference for producing better quality WLEDs

Enhancing the CRI and lumen output for the 6600 K WLED with convex-dual-layer remote phosphor geometry by applying red-emitting MGSR3SI2O8:EU2+,MN2+ phosphor

The traditional white LED product established with a single chip and a single phosphor results in a low color rendering index (CRI). The upgrade of LED package is comprised of two chips and one phosphor material and gives the higher CRI while keeping high luminous efficiency. Based on previous findings, the research paper performs the application of the two chips and two phosphors to enhance the color tunability of LEDs with different amounts and intensities of the two employed phosphors. Additionally, a color design model is built to serve the purpose of bettering the color fine-tuning of the white-light LED module. The maximum value of the difference between the measured CIE 1931 color coordinates and that of the simulated model is approximately 0.0063 around the 6600 K correlated color temperature (CCT). From the results, this study offers a quick approach to achieve the color fine tuning of a white-light LED module with a high CRI and luminous efficiency

Users' perceptions of the contribution of a University green roof to sustainable development

Universities are well placed to adopt and use the UN Sustainable Development Goals (SDGs) on their campuses to educate and showcase how the SDGs can be delivered in the built environment. Green infrastructure, such as green roofs, green walls, or green parks, are highly visual implementations with environmental and social benefits that contribute to several SDGs, such as 3 (good health and wellbeing), 10 (reduced inequalities), 11 (sustainable cities and communities), 13 (climate action) and 15 (life on land). These features may be referenced in sustainability teaching and learning, which may raise and heighten awareness of the social, economic, and environmental benefits of green infrastructure. In this study, we explored users’ perceptions of the extent to which a university campus green roof contributes to the SDGs and whether users focussed more on its social or environmental benefits. Statistical analyses, namely independent samples t-tests and analysis of variance, were conducted to determine what influenced users’ perceptions of the green roof. The analyses revealed that users’ perceptions did not differ largely by sociodemographic characteristics, though students perceived the social benefits as greater than university staff. Those with greater knowledge of green roofs perceived its environmental benefits as greater, but not the social benefits. The findings demonstrate the importance of green infrastructure on university campuses for encouraging engagement with the SDGs, whilst indicating that knowledge of such infrastructure increases appreciation of their environmental credentials

Enhanced Luminous Efficacy of White LED with Flat Dual-Layer Remote Phosphor Structure

This paper shows the differences in luminous fluxes of two distinguishing dual-layer remote phosphor structures, Flat Dual-Remote Phosphor (FDRP) and Concave Dual-Remote Phosphor (CDRP). The impact of the distance between the two phosphor layers (d_1) and the distance from the phosphor layer to the LED surface (d_2) on the optical properties of the CDRP is also presented. Specifically, when d_1 and d_2 are varied, the scattering and absorption characteristics of the remote phosphor layer change dramatically, which enormously influences the color uniformity and illumination capability of WLEDs. The concentration of YAG:Ce3+ phosphor also needs to be modified so that the correlated color temperature of WLEDs could be maintained at 8500K when d_1 and d_2 are adjusted. In case d_1 = d_2 = 0, the scattering and absorption in the remote phosphor layer are minimal, leading to the infinitesimal color and luminous flux. When d_1 and d_2 get bigger, the scattering surface increases and that the blue and yellow rays are blended becomes more uniform, leading to the minimum white light deviation as well as the lowest luminous flux. According to the studied results, the lumen output can be maximum at 1020lm if d_1 = 0.08mm or d_2 = 0.63mm while the smallest color deviation occurs when d_1 = 0.64mm or d_2 = 1.35mm. Therefore, the researched results will provide further information for choosing the suitable d_1 and d_2 in order to improve the quality of WLEDs