Cr[(H3N-(CH2)2-PO3)(Cl)(H2O)]: X-ray single-crystal structure and magnetism of a polar organic-inorganic hybrid chromium(II) organophosphonate

Cr[(H(3)N-(CH(2))(2)-PO(3))(Cl)(H(2)O)], a rare example of a polar organic-inorganic hybrid material containing Cr(2+), was prepared from CrCl(2), 2-aminoethylphosphonic acid, and urea in water and isolated as light-blue crystals. It crystallizes in the noncentrosymmetric monoclinic space group P2(1), with a = 5.249(1) A, b = 14.133(3) A, c = 5.275(1) A, and beta = 105.55(2) degrees. The inorganic layer of the hybrid network is formed by Cr(II) five-coordinated by three oxygen atoms from the phosphonates and one from the water molecule in a square pyramidal unit, whose apical position is occupied by the Cl(-) ion. Hydrogen bonds are established between the coordinating water molecule and the oxygen atoms of adjacent phosphonate ligands. The inorganic network is interspersed by ethylammonium groups, and the terminal ammonium moiety is linked to the apical Cl(-) ions through hydrogen bonds. Electrostatic interactions as well as hydrogen bonds and the coordinated chlorine atoms ensure the cohesion of the 3D structure. The lattice is polar (lack of inversion center), and this fact determines the magnetic behavior of the compound at low temperatures. The magnetic susceptibility data in the temperature range from 300 to 50 K show Curie-Weiss behavior, with C = 2.716 cm(3) K mol(-1) and the Weiss constant theta = -2.2 K. The corresponding effective magnetic moment of 4.7 mu(B) compares well with the expected value for Cr(2+) in d(4) high-spin configuration. A slight decrease of the chiT product versus T observed at temperatures below 50 K indicates nearest-neighbor antiferromagnetic exchange interactions. On cooling below T = 6 K, the magnetic susceptibility increases sharply up to a maximum at ca. 5 K and then decreases again. Below T = 6 K, hysteresis loops taken at different temperatures show that Cr[(H(3)N-(CH(2))(2)-PO(3))(Cl)(H(2)O)] behaves as a weak ferromagnet with the critical temperature T(N) at 5.5 K. The spin canting is responsible of the long-range magnetic ordering. The values of the coercive field, H(c), and of remnant magnetization, M(r), obtained from the hysteresis loop at T = 4.5 K (the lowest measured temperature) are 30 Oe and 0.08 mu(B), respectively.     

Development of novel cell-permeable DNA sensitive dyes using combinatorial synthesis and cell-based screening

A novel cell-permeable DNA fluorescence sensor was developed based on combinatorially-created styryl dyes and cell-based localization screening.     

Mapping of the relaxation patterns of polymer melts with linear flexible molecules of uniform length

The linear viscoelastic material functions of linear flexible polymers of uniform length are calculated from the BSW spectrum (Baumgaertel et al., 1990, 1992), and explicit analytic expressions are presented for several of the most common material functions for transient and dynamic experiments. However, numerical calculations are presented whenever needed. The BSW spectrum was determined from experimental G, G data of two sets of molten polymers of narrow molecular weight distribution, polystyrene and polybutadiene. The purpose of the mapping is to show a wide range of viscoelastic behavior which otherwise is not available in such comprehensive form. Experimental check of these predictions is still needed in most cases. Also, some insight into the predictions for the non-linear (including the non-equilibrium) viscoelastic behavior is achieved by studying two particular experiments: the start-up of uniaxial extension at constant rate and the start-up of shear flow at constant rate.Dedicated to Prof. John D. Ferry on the occasion of his 85th birthday.     

The behaviour of several stress–velocity–pressure mixed finite elements for Newtonian flows

The Q₂/P₁, P/P₁, P₂/P₀ and Q₁/P₀ velocity–pressure mixed elements are extended to the stress–velocity–pressure formulation, using the same interpolants for stress and velocity, and tested in the 4-to-1 contraction problem for Stokes flow. The comparison shows significant differences among them, which are not present when the velocity–pressure formulation is used. To provide a better understanding of the phenomenon, several variants of the previous elements are introduced, obtained by either changing the pressure space or by enriching the stress space with bubble functions. The formulation exhibits a strong sensitivity to the first alternative, while the second produces only a minor effect. These observations are confirmed by a convergence test effected on a regular problem with the explicit analytical solution. Also, as a result of the whole comparison, the P/P/P₁ element looks promising for three-field calculations.     

A dynamic analysis of the aluminum titanate (Al2TiO5) reaction-sintering from alumina and titania,properties and effect of alumina particle size

Journal of Thermal Analysis and Calorimetry - Aluminum titanate Al2TiO5 materials were successfully processed from different fine commercial powders and characterized. Particularly, two calcined...     

Photo-assisted charge/discharge of a secondary cell of α-Fe2O3/Prussian blue–based electrodes

Journal of Solid State Electrochemistry - In this work, an assembly of FTO/α-Fe2O3/PB|M+ electrolyte|PB/α-Fe2O3/FTO (M+ = Li+, Na+, K+) secondary photocell was done to improve...     

Anthocyanins Recovered from Agri-Food By-Products Using Innovative Processes: Trends,Challenges, and Perspectives for Their Application in Food Systems

Anthocyanins are naturally occurring phytochemicals that have attracted growing interest from consumers and the food industry due to their multiple biological properties and technological applications. Nevertheless, conventional extraction techniques based on thermal technologies can compromise both the recovery and stability of anthocyanins, reducing their global yield and/or limiting their application in food systems. The current review provides an overview of the main innovative processes (e.g., pulsed electric field, microwave, and ultrasound) used to recover anthocyanins from agri-food waste/by-products and the mechanisms involved in anthocyanin extraction and their impacts on the stability of these compounds. Moreover, trends and perspectives of anthocyanins’ applications in food systems, such as antioxidants, natural colorants, preservatives, and active and smart packaging components, are addressed. Challenges behind anthocyanin implementation in food systems are displayed and potential solutions to overcome these drawbacks are proposed.     

Poly-symmetry in processor-sharing systems

We consider a system of processor-sharing queues with state-dependent service rates. These are allocated according to balanced fairness within a polymatroid capacity set. Balanced fairness is known to be both insensitive and Pareto-efficient in such systems, which ensures that the performance metrics, when computable, will provide robust insights into the real performance of the system considered. We first show that these performance metrics can be evaluated with a complexity that is polynomial in the system size if the system is partitioned into a finite number of parts, so that queues are exchangeable within each part and asymmetric across different parts. This in turn allows us to derive stochastic bounds for a larger class of systems which satisfy less restrictive symmetry assumptions. These results are applied to practical examples of tree data networks, such as backhaul networks of Internet service providers, and computer clusters.     

Production of enantiopure β-amino-γ-hydroxyesters from benzoic acid by a selective formal aminohydroxylation

The enantioselective preparation of three protected β-amino-γ-hydroxyesters from benzoic acid is described. The employed synthetic methodology involves the ipso, ortho cis-dihydroxylation of benzoic acid by the mutant strain Ralstonia eutropha B9, followed by a selective halonium induced beta lactamization. Modification of this novel β-lactam structure by the appropriate sequence of reactions allows for the selective preparation of the aforementioned β-amino-γ-hydroxyesters in a diastereodivergent manner. The overall transformation results in a selective formal aminohydroxylation of the diene moiety of the initial cis-cyclohexadienediol. The synthesized products are important building blocks and will allow for the selective preparation of aminoacids, inosamines and alkaloids from benzoic acid.     

Bioanalysis by Immobilization of Antibodies on Hafnium(IV) Oxide with 3-Aminopropyltriethoxysilane

Self-assembled monolayers of 3-aminopropyltriethoxysilane (APTES) are commonly used to promote adhesion between substrates and organic or metallic materials with applications ranging from advanced composites to biomolecular lab-on-a-chip devices. In this work, the silanization on hafnium oxide (HfO₂) films is reported. The layers of HfO₂ were deposited on Si (001) substrates by atomic layer deposition. The grown HfO₂ films were modified in accordance with three main steps: oxidation, silanization, and cross-linking of the APTES monolayer using glutaraldehyde as cross-linking agent. Microscopic features were characterized by atomic force microscopy. Further, both bovine serum albumin and antibovine serum albumin agents were deposited on the samples to test their potential use as the immunosensor.