Memorial University of Newfoundland

About: Memorial University of Newfoundland is a education organization based out in St. John's, Newfoundland and Labrador, Canada. It is known for research contribution in the topics: Population & Context (language use). The organization has 13818 authors who have published 27785 publications receiving 743594 citations. The organization is also known as: Memorial University & Memorial University of Newfoundland and Labrador.

Simple Diamine- and Triamine-Protonic Acid Catalysts for the Enantioselective Michael Addition of Cyclic Ketones to Nitroalkenes

Abstract: Simple, chiral, pyrrolidine-based diamine and triamine derivatives that incorporate the secondary−secondary diamine motif are efficient catalysts for the highly diastereoselective and enantioselective Michael addition of cyclic ketones to 2-nitrovinyl arenes The highest selectivities are obtained when these catalysts are used in conjunction with protonic acids Steric factors in the substrate and the size of the acid additive play an important role in stereoselection

Gold and silver nanoparticles from Trianthema decandra: synthesis, characterization, and antimicrobial properties.

Abstract: Background There is an increasing commercial demand for nanoparticles due to their wide applicability in various markets, including medicine, catalysis, electronics, chemistry, and energy. In this report, a simple and ecofriendly chemical reaction for the synthesis of gold and silver nanoparticles from Trianthema decandra (Aizoaceae) has been developed. Methods and results On treatment of aqueous solutions containing chloroauric acid or silver nitrate with root extract of T. decandra, stable gold or silver nanoparticles were rapidly formed. The kinetics of reduction of gold and silver ions during the reaction was analyzed by ultraviolet-visible spectroscopy. Field emission-scanning electron microscopy showed formation of gold nanoparticles in various shapes, including spherical, cubical, triangular, and hexagonal, while silver nanoparticles were spherical. The size of the gold nanoparticles was 33-65 nm and that of the silver nanoparticles was 36-74 nm. Energy dispersive x-ray and Fourier transform infrared spectroscopy confirmed the presence of metallic gold and metallic silver in the respective nanoparticles. The antimicrobial properties of the synthesized nanoparticles were analyzed using the Kirby-Bauer method. The results show varied susceptibility of microorganisms to the gold and silver nanoparticles. Conclusion It is believed that phytochemicals present in T. decandra extract reduce the silver and gold ions into metallic nanoparticles. This strategy reduces the cost of production and the environmental impact. The silver and gold nanoparticles formed showed strong activity against all microorganisms tested.

On-line adaptive artificial neural network based vector control of permanent magnet synchronous motors

Abstract: This paper presents a novel approach of speed control for a permanent magnet synchronous motor (PMSM) using on-line self tuning artificial neural network (ANN). Based on motor dynamics and nonlinear load characteristics, an ANN speed controller is developed and integrated with the vector control scheme of the PMSM drive. The combined use of off-line and on-line weights and biases adjustments offers a unique feature of on-line system identification and precise speed control of a high performance PMSM drive. The complete drive system is implemented in real time using a digital signal processor controller board-DS1102 on a laboratory 1 HP PMSM. Using the experimental setup, the performances of the proposed drive system are evaluated under various operating conditions. The test results validate the efficacy of the ANN for precise speed control of the PMSM drive. Furthermore, the use of ANN makes the drive system robust, accurate and insensitive to parameter variations.

Case–Control Study of Overweight, Obesity, and Colorectal Cancer Risk, Overall and by Tumor Microsatellite Instability Status

Abstract: status. Methods The study included 1794 case subjects with incident colorectal cancer who were identified through populationbased cancer registries and 2684 of their unaffected sex-matched siblings as control subjects. Recent body mass index (BMI), BMI at age 20 years, and adult weight change were derived from self-reports of height and weight. Tumor MSI status, assessed at as many as 10 markers, was obtained for 69.7% of the case subjects and classified as microsatellite (MS)-stable (0% of markers unstable; n = 913), MSI-low (>0% but <30% of markers unstable; n = 149), or MSI-high (≥30% of markers unstable; n = 188). Multivariable conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs). All statistical tests were two-sided. Results Recent BMI, modeled in 5 kg/m 2 increments, was positively associated with risk of colorectal cancer for men and women combined (OR = 1.24; 95% CI = 1.15 to 1.34), for women only (OR = 1.20; 95% CI = 1.10 to 1.32), and for men only (OR = 1.30; 95% CI = 1.15 to 1.47). There was no interaction with sex (P = .22). Recent BMI, per 5 kg/m 2 , was positively associated with the risk of MS-stable (OR = 1.38; 95% CI = 1.24 to 1.54) and MSI-low (OR = 1.33; 95% CI = 1.04 to 1.72) colorectal tumors, but not with the risk of MSI-high tumors (OR = 1.05; 95% CI = 0.84 to 1.31). Conclusion The increased risk of colorectal cancer associated with a high BMI might be largely restricted to tumors that display the more common MS-stable phenotype, suggesting further that colorectal cancer etiology differs by tumor MSI status.