Synthesis,characterization, crystal structure and antiproliferative activity of platinum(II) complexes with 2-acetylpyridine-4-cyclohexyl-thiosemicarbazone

New platinum complexes have been synthesized by the reaction of Na₂PtCl₄ with 2-acetylpyridine-4-cyclohexyl-thiosemicarbazone, HAc4CyclHexyl (1). The new complexes [Pt(Ac4CyclHexyl)Cl] (2) and [Pt(Ac4CyclHexyl)₂] (3) have been characterized by elemental analyses and spectroscopic studies. The crystal structure of the complex [Pt(Ac4CyclHexyl)Cl] · DMF has been solved by single-crystal X-ray diffraction. The anion of Ac4CyclHexyl coordinates in a planar conformation to the central platinum(II) through the pyridyl N, azomethine N and thiolato S atoms. The crystal packing is determined by double intermolecular hydrogen interactions, π–π, Pt–C and Pt–π contacts. The cytotoxic activities of 1–3 have been evaluated for antiproliferative activity in vitro against the cells of three human cancer cell lines: MCF-7 (human breast cancer cell line), T24 (bladder cancer cell line), A-549 (non-small cell lung carcinoma) and a mouse L-929 (a fibroblast-like cell line cloned from strain L). The compounds 1–3 display IC₅₀ values in a μM range better than that of the antitumor drug cisplatin and are considered as agents with potential antitumor activity candidates for further stages of screening in vitro and/or in vivo.     

Constrained numerical optimization methods for blind deconvolution

This paper describes a nonlinear least squares framework to solve a separable nonlinear ill-posed inverse problem that arises in blind deconvolution. It is shown that with proper constraints and well chosen regularization parameters, it is possible to obtain an objective function that is fairly well behaved and the nonlinear minimization problem can be effectively solved by a Gauss–Newton method. Although uncertainties in the data and inaccuracies of linear solvers make it unlikely to obtain a smooth and convex objective function, it is shown that implicit filtering optimization methods can be used to avoid becoming trapped in local minima. Computational considerations, such as computing the Jacobian, are discussed, and numerical experiments are used to illustrate the behavior of the algorithms. Although the focus of the paper is on blind deconvolution, the general mathematical model addressed in this paper, and the approaches discussed to solve it, arise in many other applications.     

The Effect of a Horseshoe Crab Citizen Science Program on Middle School Student Science Performance and STEM Career Motivation

The purpose of the present quasi‐experimental study was to examine the impact of a horseshoe crab citizen science program on student achievement and science, technology, engineering, and mathematics (STEM) career motivation with 86 (n = 86) eighth‐grade students. The treatment group conducted fieldwork with naturalists and collected data for a professional biologist studying horseshoe crab speciation and a mock survey. The comparison group studied curriculum related to horseshoe crabs in the science classroom. A series of measures related to self‐efficacy, interest, outcome expectations, choice goals, and content knowledge were given to participants before and after the intervention. It was hypothesized that students would report higher motivational beliefs regarding science and show higher levels of achievement following the intervention than the comparison group. Support was shown for most of the hypotheses. In addition, path analyses indicated that students' motivational beliefs influence content knowledge and outcome expectations, which in turn affect their career goals. These results have implications for incorporating authentic fieldwork within a formal school structure as an effective method for promoting student achievement and STEM career motivation.     

Smoothness characterization and stability of nonlinear and non-separable multiscale representations

The aim of the paper is the construction and the analysis of nonlinear and non-separable multiscale representations for multivariate functions defined using a non-diagonal dilation matrix M. We show that a function in L^p or Besov spaces can be characterized by means of its multiscale representation. We also study the stability of these representations, a key issue to design adaptive algorithms.     

Ion chromatographic method for the determination of cations of group IA and IIA in water samples, pharmaceuticals and energy drinks by non-suppressed conductometric detection

An efficient ion chromatographic (IC) method was developed for the simultaneous quantitative determination of Li⁺, Na⁺, NH₄ ⁺, K⁺, Cs⁺, Ca²⁺, Mg²⁺, Sr²⁺, Ba²⁺ and Be²⁺ in energy drinks, pharmaceutical and drinking water samples by non-suppressed conductometric detection. The separation of ten cations including ammonium was achieved using a cation-exchange column and low conductivity mobile phase. The mobile phase consisted of tartaric acid, dipicolinic acid and boric acid. The separation of the cations was completed in less than 18 min, with a flow rate of 1.2 mL min⁻¹. The separation was not affected by the existence of cations Co²⁺, Cr³⁺, Cd²⁺, Cu²⁺, Bi³⁺, Ag⁺, Fe³⁺ and Zn²⁺ in concentrations up to 20 mg L⁻¹. Using an injection volume of 20 μL the obtained detection limits were 0.003 mg L⁻¹, 0.02 mg L⁻¹, 0.01 mg L⁻¹, 0.01 mg L⁻¹, 0.10 mg L⁻¹, 0.01 mg L⁻¹, 0.02 mg L⁻¹, 0.02 mg L⁻¹, 0.003 mg L⁻¹ and 0.1 mg L⁻¹, for Li⁺, Na⁺, NH⁴⁺, K⁺, Cs⁺, Ca²⁺, Mg²⁺, Sr²⁺, Be²⁺ and Ba²⁺ respectively. The intra-day repeatability (RSD%, n=5) ranged from 1.1% to 4.8%, and the inter-day (n=5) between 1.8% and 5.4% respectively. The method was applied to the analysis of various bottled and tap water, pharmaceutical preparations and energy drinks commercially available.      

Synthetic studies toward A-74528

A potentially biomimetic approach toward the complex polyketide A-74528 is described. It is based on highly substituted biaryl compounds, synthesized using advanced cross-coupling and condensation methodologies.     

Synthesis of Novel Saccharide Hydrazones

Synthesis of important heterocyclic hydrazine derivatives N-aminopyrrolidine, N-aminopiperidine, and N-aminoazepane from hydrazine hydrate and dihalogenides were examined and optimized. These heterocyclic hydrazine derivatives were used in condensation reactions with six different monosaccharides to form corresponding hydrazones. Biological evaluations of these novel compounds, which are simple acyclic nucleoside analogs, were done. L-Arabinose N-aminoazepane hydrazone showed minor anti-HIV activity, giving a starting point for further structural modifications.     

Formation of bimetallic Au-Pd and Au-Pt nanoparticles under hydrothermal conditions and microwave irradiation

The reduction of chlorocomplexes of gold(III) from muriatic solutions by nanocrystal powders of palladium and platinum at 110 and 130 °C under hydrothermal conditions and the action of microwave irradiation has been investigated. The structure and composition of the solid phase have been characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and chemical methods. Bimetallic particles with a core-shell structure have been revealed. The obtained particles are established to have a core of the metal reductant covered with a substitutional solid (Au, Pd) solution in case of palladium, and isolated by a gold layer in the case of platinum. The main reason for such a difference is the ratio between the rates of aggregation and reduction. It has been shown by the example of the Au-Pd system that the use of microwave irradiation allows us not only to accelerate the synthesis of particles but also to obtain more homogeneous materials in comparison with conventional heating.