Sol gel synthesis of 3-n-propyl(4-aminomethyl)pyridinium silsesquioxane chloride and the enhanced electrocatalytic activity of LbL films

Journal of Sol-Gel Science and Technology - A silsesquioxane based on a silica matrix and 4-(aminomethyl)pyridine group was successfully synthesized using the sol–gel process with the...     

Use of capillary electrophoresis with laser-induced fluorescence detection to screen and liquid chromatography–tandem mass spectrometry to confirm sulfonamide residues: Validation according to European Union 2002/657/EC

A multiresidue method is described for determining six sulfonamides (SAs) (sulfadiazine, sulfathiazole, sulfamethazine, sulfamethoxazole, sulfaquinoxaline and sulfadimethoxine) in liver by a capillary electrophoresis screening method and a liquid chromatography coupled to tandem mass spectrometry confirmatory assay. Samples were prepared by homogenizing the tissue, with sodium hydroxide and acetonitrile. After evaporation, extracts were injected in the capillary electrophoresis system or mass spectrometry system for confirmatory analysis. The detection of analytes was achieved by laser-induced fluorescence in capillary electrophoresis. Procedures were validated according to the European Union regulation 2002/657/EC determining specificity, selectivity and detection capability for screening method and decision limit, detection capability, specificity, selectivity, trueness and precision for confirmation method. The results of validation process demonstrate that the method is suitable for application in Brazilian statutory veterinary drug residue surveillance programs. Capillary electrophoresis was proved to be a fast, robust method with low time and reagents consumption.     

Simultaneous determination of aluminoxamine and ferrioxamine in post-hemodialysis fluids by spectrophotometry and multivariate calibration

A spectrophotometric method for simultaneous determination of Al(III) and Fe(III) using the chelator Desferal® (desferrioxamine B) was developed. Partial least squares (PLS) regression was performed to resolve the overlapped signals obtained from Al(III) and Fe(III) complexes. The parameters controlling behavior of the system were investigated and optimum conditions were selected. PLS was the choice for the analysis of binary mixtures of Fe(III) and Al(III) over the range of 0.1 to 0.8 mg L^?1 by using the data of first derivative spectra. Absorbance data were taken between 200 and 600 nm. The calculated sensitivity values for the multivariate method were 4.88 and 5.64 for Al(III) and Fe(III), respectively. Multivariate detection limits were 0.075 and 0.064 mg L^?1 for Al(III) and Fe(III), respectively. The method was applied to real post-hemodialysis samples, and sample digestion by UV irradiation was discussed.     

Highly sensitive photoelectrochemical immunosensor based on anatase/rutile TiO2 and Bi2S3 for the zero-biased detection of PSA

Journal of Solid State Electrochemistry - A novel label-free photoelectrochemical immunosensor was developed for the determination of prostate-specific antigen (PSA) based on fluorine-doped tin...     

The two-echelon production-routing problem

This paper introduces the Two-Echelon Production-Routing Problem. This problem is motivated from the petrochemical industry, enlarging the supply chain integration by taking into account production, inventory, and routing decisions in a two-echelon vendor-managed inventory system. We describe, model, and design a branch-and-cut (B&C) to solve the problem under different inventory policies. We also propose a novel exact algorithm, by employing parallel computing techniques, in order to combine local search procedures within a traditional B&C scheme. We evaluate the performance of our methods through extensive computational experiments, both by comparing the algorithms, the effectiveness of the different inventory policies, and the impact of these policies on the partial costs. We derive many managerial insights based on the results. We also validate our new exact algorithm by solving similar problems from the literature, such as the two-echelon multi-depot inventory-routing (2E-MDIRP) and the classical multi-vehicle production-routing problem (MV-PRP). Computational experiments show that our method is very competitive. Based on 512 experiments for the 2E-MDIRP, our algorithm was able to find 111 new best known solutions (BKS), besides proving 412 optimal solutions, against 298 from the literature. For 336 experiments over small and medium size MV-PRP instances, we proved 242 optimal solutions, 11 more than the exact methods from the literature, besides providing 95 new BKS. Moreover, we were the first to tackle large MV-PRP instances exactly, and in this case, our algorithm provides all BKS for instances up to 50 customers, 20 periods and 5 vehicles, outperforming all meta/matheuristics procedures from the literature.     

A bias-variance analysis of state-of-the-art random forest text classifiers

Advances in Data Analysis and Classification - Random forest (RF) classifiers do excel in a variety of automatic classification tasks, such as topic categorization and sentiment analysis. Despite...     

The renormalized Jellium model of colloidal suspensions with multivalent counterions

An extension of the renormalized Jellium model which allows to study colloidal suspensions containing trivalent counterions is proposed. The theory is based on a modified Poisson-Boltzmann equation which incorporates the effects of counterion correlations near the colloidal surfaces using a new boundary condition. The renormalized charges, the counterion density profiles, and osmotic pressures can be easily calculated using the modified renormalized Jellium model. The results are compared with the ones obtained using the traditional Wigner-Seitz (WS) cell approximation also with a new boundary condition. We find that while the thermodynamic functions obtained within the renormalized Jellium model are in a good agreement with their WS counterpart, the effective charges predicted by the two theories can be significantly different.     

Linearization of multipolynomials and applications

We prove that every multipolynomial between Banach spaces is the composition of a canonical multipolynomial with a linear operator, and that this correspondence establishes an isometric isomorphism between the spaces of multipolynomials and linear operators. Applications to composition ideals of multipolynomials and to multipolynomials that are of finite rank, approximable, compact, and weakly compact are provided.     

The odd log-logistic Topp–Leone G family of distributions: heteroscedastic regression models and applications

We introduce a new class of distributions and provide a comprehensive treatment of its mathematical properties. The maximum likelihood method is discussed to estimate the parameters of the new model by means of Monte-Carlo simulation study. The heteroscedastic regression models with long-term survival are introduced to model data sets with the non homogeneity of the error variances in the presence of cured individuals. The potentiality of the proposed models is illustrated by means of four real data sets.     

Chemoenzymatic synthesis of boron-containing chiral amines and amides

The first application of lipases as catalysts to obtain optically active boron-containing amines and amides is described. We studied several reaction conditions to achieve the kinetic resolution of boron-containing amines via enantioselective acylation mediated by Candida antarctica lipase B (CAL-B). Excellent enantioselectivity (E >200) and high enantiomeric excess (up to >99%) of both the remaining amines and amides were obtained.