Metal-organotetraphosphonate inorganic-organic hybrids: crystal structure and anticorrosion effects of zinc hexamethylenediaminetetrakis(methylenephosphonate) on carbon steels

The synthesis and structural characterization of the first polymeric M-HDTMP organic-inorganic hybrids are described [M = Zn2+, Ca2+; HDTMP = hexamethylenediaminetetrakis(methylenephosphonate)]. The 3D crystal structure of the Zn2+ analogue [Zn(HDTMP) x H2O] is described. The Zn center is found in a distorted octahedral environment of phosphonate oxygens. There is a long Zn...O interaction (2.622 A) originating from a protonated -P-OH group. Synergistic combinations of Zn2+ and the tetraphosphonate are found to form films that protect against the corrosion of carbon steels.     

Polymerization of n‐hexyl isocyanate with CpTiCl2(OR) (R = functional group or macromolecular chain): A route to ω‐functionalized and block copolymers and terpolymers of n‐hexyl isocyanate

Well‐defined ω‐cholesteryl poly(n‐hexyl isocyanate) (PHIC–Chol), as well as diblock copolymers of n‐hexyl isocyanate (HIC) with styrene, PS‐b‐PHIC [PS = polystyrene; PHIC = poly(n‐hexyl isocyanate)], and triblock terpolymers with styrene and isoprene, PS‐b‐PI‐b‐PHIC and PI‐b‐PS‐b‐PHIC (PI = polyisoprene), were synthesized with CpTiCl₂(OR) (R = cholesteryl group, PS, or PS‐b‐PI) complexes. The synthetic strategy involved the reaction of the precursor complex CpTiCl₃ with cholesterol or the suitable ω‐hydroxy homopolymer or block copolymer, followed by the polymerization of HIC. The ω‐hydroxy polymers were prepared by the anionic polymerization of the corresponding monomers and the reaction of the living chains with ethylene oxide. The reaction sequence was monitored by size exclusion chromatography, and the final products were characterized by size exclusion chromatography (light scattering and refractive‐index detectors), nuclear magnetic resonance spectroscopy, and, in the case of PHIC–Chol, differential scanning calorimetry. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6503–6514, 2005     

Über die Wirkung von Auxochromen in Flavyliumsalzen,III. 7-Dimethylamino-flavyliumsalze

The absorption maximum at longest wave lengths of the 7-dimethylaminoflavylium perchlorate being shifted by 121 nm to longer wave lengths than the maximum of the flavylium perchlorate and yet the auxochromes in 4′-position having a less strong effect in the 7-dimethylamino-flavylium salts than in the flavylium salts, the absorption maxima of both series converge strongly. In the case of the 4′-dimethylamino derivatives the convergence reaches the high value of 61 nm.     

Theoretical Investigation of the Stepwise Hydrolysis of the [Re3(μ‐Cl)3Cl9]3‐ Anion

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.     

A quantitative western blot technique using TMB: Comparison with the conventional technique

Numerous molecular biological experiments performed throughout the world require the detection or quantification of a protein of interest. Western blotting is one of the most popular techniques used for this purpose and offers quantitative information with the aid of specialized software. However, its dependence on the picture that is captured, and the background and the absence of a common protocol prevent the technique from being completely quantitative. To overcome these obstacles, we present a simple and reliable assay that is similar to the regular technique, with the exception of the last stage of band visualization and quantification. We propose that small pieces of the blot that include the protein of interest can be cut and dipped in a small volume of 3,3',5,5'-tetramethylbenzidine solution, giving a colorimetric signal with linear dependence on the quantity of the protein. The reaction is stopped with H₂SO₄, and the signal is measured in a plate reader. This modification shows high linearity without additional costs and can be applied for both purified proteins and proteins found in a lysate. The results obtained with our proposed technique were compared with those obtained by the conventional method and proved to be more reliable.     

Voltammetric Determination of Trace Heavy Metals by Sequential-injection Analysis at Plastic Fluidic Chips with Integrated Carbon Fiber-based Electrodes

This work describes a sequential injection analysis (SIA) method for on-line strippping voltammetric determination of Pb(II), Cd(II) and Zn(II) using an injection-moulded electrochemical fluidic chip consisting of 3 conductive carbon fiber-loaded polymer electrodes embedded in a plastic fluidic holder. The sample containing the target metals and a solution containing Bi(III) were aspirated in the holding coil of the SIA manifold. Then, the flow was reversed and the two solutions were directed to the fluidic cell through a mixing coil which induced mixing of the two zones. Upon reaching the cell, simultaneous reduction of the target metals and Bi(III) occurred resulting in the formation of a metal-Bi alloy on the working electrode. Finally, the accumulated metals were stripped off the bismuth-film electrode via a positive potential scan and the oxidation current was recorded. The experimental variables (concentration of the bismuth plating solution, deposition potential, sample volume, stripping mode) were investigated and the potential interferences were assessed. The limits of quantification were 2.8 μg L⁻¹ for Pb(II), 3.6 μg L⁻¹ for Cd(II) and 4.2 μg L⁻¹ for Zn(II) and the the within-chip and between-chip % relative standard deviations were ≤6.3 % and ≤14 %, respectively. Finally, the sensor was applied to the determination of trace metals in a fish food sample.     

Rapid Microwave-Assisted Synthesis of CdS/Graphene/MoSx Tunable Heterojunctions and Their Application in Photocatalysis

Nanoscale two-dimensional nanostructures have shown great potential as functional components in photocatalysis. Here, investigations on the synthesis of heterostructured hybrids, comprised of 0D CdS nanoparticles as semiconductor and 2D/2D graphene/MoS_x as co-catalyst, are reported. The approach involves a rapid microwave-assisted reaction in autoclave conditions, by adopting either a one-step or a two-step protocol. The chemical speciation of the nanocomposites was found to depend strongly on the compounding conditions of the precursor substances. The photocatalytic activity was assessed by monitoring the photodegradation rate of 4-nitrophenol in solution using simulated solar light irradiation. The photocatalytic activity of the hybrids may be attributed to a combination of beneficial characteristics, strongly related to the chemical speciation of the composite components. Moreover, intimate contacts of the latter result in efficient heterojunctions. Overall, the present study provides valuable insight into the development of functional heterostructured photocatalysts comprised of two-dimensional nanomaterials.     

A survey on algorithmic approaches for solving tourist trip design problems

The tourist trip design problem (TTDP) refers to a route-planning problem for tourists interested in visiting multiple points of interest (POIs). TTDP solvers derive daily tourist tours, i.e., ordered visits to POIs, which respect tourist constraints and POIs attributes. The main objective of the problem discussed is to select POIs that match tourist preferences, thereby maximizing tourist satisfaction, while taking into account a multitude of parameters and constraints (e.g., distances among POIs, visiting time required for each POI, POIs visiting days/hours, entrance fees, weather conditions) and respecting the time available for sightseeing on a daily basis. The aim of this work is to survey models, algorithmic approaches and methodologies concerning tourist trip design problems. Recent approaches are examined, focusing on problem models that best capture a multitude of realistic POIs attributes and user constraints; further, several interesting TTDP variants are investigated. Open issues and promising prospects in tourist trip planning research are also discussed.     

Theoretical and algorithmic advances in multi-parametric programming and control

This paper presents an overview of recent theoretical and algorithmic advances, and applications in the areas of multi-parametric programming and explicit/multi-parametric model predictive control (mp-MPC). In multi-parametric programming, advances include areas such as nonlinear multi-parametric programming (mp-NLP), bi-level programming, dynamic programming and global optimization for multi-parametric mixed-integer linear programming problems (mp-MILPs). In multi-parametric/explicit MPC (mp-MPC), advances include areas such as robust multi-parametric control, multi-parametric nonlinear MPC (mp-NMPC) and model reduction in mp-MPC. A comprehensive framework for multi-parametric programming and control is also presented. Recent applications include a hydrogen storage device, a fuel cell power generation system, an unmanned autonomous vehicle (UAV) and a hybrid pressure swing adsorption (PSA) system.