Copper pyrovanadate electrodes prepared by combustion synthesis: evaluation of photoelectroactivity

Journal of Solid State Electrochemistry - Photoelectrodegradation of dyes using semiconductors under visible light is currently a major research topic. In this work, copper pyrovanadate (Cu2V2O7)...     

A matheuristic for the cell formation problem

In this paper we propose a GRASP matheuristic coupled with an Integer Programming refinement based on Set Partitioning to solve the Cell Formation Problem. We use the grouping efficacy measure to evaluate the solutions. As this measure is nonlinear, we propose a fractional Set Partitioning approach and its linearization. Our method is validated on a set of 35 instances from the literature. The experiments found four unknown solutions. For all instances with known optima, our method is able to determine the optimum solutions.     

Optimization Over the Boolean Hypercube Via Sums of Nonnegative Circuit Polynomials

Various key problems from theoretical computer science can be expressed as polynomial optimization problems over the boolean hypercube. One particularly successful way to prove complexity bounds for these types of problems is based on sums of squares (SOS) as nonnegativity certificates. In this article, we initiate optimization problems over the boolean hypercube via a recent, alternative certificate called sums of nonnegative circuit polynomials (SONC). We show that key results for SOS-based certificates remain valid: First, for polynomials, which are nonnegative over the n-variate boolean hypercube with constraints of degree d there exists a SONC certificate of degree at most \(n+d\). Second, if there exists a degree d SONC certificate for nonnegativity of a polynomial over the boolean hypercube, then there also exists a short degree d SONC certificate that includes at most \(n^{O(d)}\) nonnegative circuit polynomials. Moreover, we prove that, in opposite to SOS, the SONC cone is not closed under taking affine transformation of variables and that for SONC there does not exist an equivalent to Putinar’s Positivstellensatz for SOS. We discuss these results from both the algebraic and the optimization perspective.

     

Combined application of DP4+ and ANN-PRA to determine the relative configuration of natural products: The alpha-bisabol case study

The combination of computational methods and experimental data from Nuclear Magnetic Resonance (NMR) is a considerably valuable tool in the elucidation of new natural product structures and, also, in the structural revision of previously reported compounds. Until recently, only classical statistical parameters were used, for example, linear correlation coefficient (R²), mean absolute error (MAE), or root mean square deviation (RMSD), as a way to statistically “validate” the structure pointed out by experimental NMR spectra. Regarding the resolution of the relative configuration of organic molecules, novel tools were available in the last few years to assist in the NMR elucidation process. The most relevant are DP4+, which is based on a Bayesian probability, and ANN-PRA, which is based on artificial neural networks. The combined application of these tools has become the most accurate and important alternative to solve structural and stereochemical problems in natural product chemistry. Therefore, herein, in this case study, we intended to promote these novel tools, exploring the strengths and limitations of each approach in resolving the relative configuration of the sesquiterpene alpha-bisabol. We also highlighted the advantages of the complementary use of H- and C-DP4+ to obtain optimal results in the differentiation of the stereoisomers, validating the proposal with ANN-PRA method.     

Photocatalytic properties of Zn2SnO4 powders prepared by different modified hydrothermal routes

Research on Chemical Intermediates - In this work, different synthesis methods of zinc stannate (Zn2SnO4–ZTO) were proposed in order to obtain a material with a...     

Uptake and depletion of the antibiotic sulfadiazine 14C in rainbow trout (Oncorhynchus mykiss)

Journal of Radioanalytical and Nuclear Chemistry - Sulfadiazine is an antibiotic used in animals and humans, this molecule is being released increasingly into the aquatic environment, which is why...     

Role of raw feedstock and biochar amendments on sorption-desorption and leaching potential of three 3H- and 14C-labelled pesticides in soils

Journal of Radioanalytical and Nuclear Chemistry - This paper describes measurement of residence time distributions (RTD) of the liquid phase in an industrial-scale continuous pulp digester. The...     

A new approach for the total synthesis of spilanthol and analogue with improved anesthetic activity

A 5-step synthesis of spilanthol (affinin) is reported, where the route features complete control of alkene geometry during the assembling of the double bonds, with the use of a Sonogashira cross-coupling reaction, a Z-selective alkyne semi-reduction and a HWE olefination reaction as the key steps. A simplified analogue was also prepared in 4 steps. Both compounds were found to permeate dermatomed pig ear skin through an in vitro Franz-type diffusion cell. The simplified analogue presented a superior anesthetic effect in vivo, using the tail flick model, when compared to spilanthol and to the commercial standard EMLA^®. These results suggest that both spilanthol and its analogue could be useful as a topical anesthetic in clinical practice.     

Thermal,spectroscopic and antimicrobial activity characterization of some norfloxacin complexes

Journal of Thermal Analysis and Calorimetry - Coordination compounds of transition metals with norfloxacin (Nor) have potential to improve its effectiveness, as already discussed for some compounds...     

Synthesis and characterization of a biopolymer of glycerol and macadamia oil

Journal of Thermal Analysis and Calorimetry - The present study investigates the conjugate heat transfer in a square cavity heated by a triangular solid and saturated with $$\text{Al}_2\text{O}_3$$...