Sorption and thermal properties of strongly basic cross‐linked ionic polymer modified with Cr(III) compounds

AV‐17(Cr) material was prepared by modifying a commercial polymer AV‐17 (initially bearing R4N⁺ functional groups) with Cr(III) compounds was investigated. Comparative isotherms characterizing the and ion sorption from solution with pH values of 3 and 8, respectively, at 19°C and 60°C, were obtained using the raw AV‐17(Cl) and the modified AV‐17(Cr) material. The sorption process on AV‐17(Cr) takes place through the coordination of Cr(VI) ions with Cr(III) ions, while on AV‐17(Cl) it is due to an ion exchange mechanism. The sorption isotherms obtained in pH 8 solutions fit perfectly the Langmuir model. The thermodynamic functions ΔG, ΔH, and ΔS characteristic to the adsorption of ions from K₂CrO₄ solutions with pH = 8 were calculated. The active sites belonging to the AV‐17(Cr) material were identified as jarosite type compounds of Cr(III). SEM images show that the Cr(III) compounds are present in the form of ultrafine particles located on the surface and within the bulk phase of the polymer granules. Comparative thermal degradation process of both the AV‐17(Cr) and the AV‐17(Cl) material was conducted in air and in an inert atmosphere (He). The thermal degradation mechanism of sorbent AV‐17(Cr) and exchanger AV‐17(Cl) is proposed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41306.     

Enzymatic synthesis of position-specific low-calorie structured lipids

An immobilized sn-1,3-specific lipase from Rhizomucor miehei (IM 60) was used to catalyze the interesterification of tristearin (C_18:0) and tricaprin (C_10:0) to produce low-calorie structured lipids (SL). Acceptable product yields were obtained from a 1:1 mole ratio of both triacylglycerols with 10% (w/w of reactants) of IM 60 in 3 mL hexane. The SL molecular species, based on total carbon number, were 44.2% C₄₁ and 40.5% C₄₉, with 3.8 and 11.5% unreacted tristearin C₅₇ and tricaprin C₂₇, respectively, remaining in the product mixture. The best yield of C₄₁ species (44.3%) was obtained with zero added water. Tricaprylin (C_8:0) was also successfully interesterified with tristearin in good yields at 1:1 mole ratio. Products were analyzed by reverse-phase high-performance liquid chromatography with an evaporative light-scattering detector. Reaction parameters, such as substrate mole ratio, enzyme load, time course, added water, reaction media, and enzyme reuse, were also investigated. Hydrolysis by pancreatic lipase revealed the specific fatty acids present at the sn-1,3 positions of SL. Biocatalysis Symposium Paper, presented at the AOCS Annual Meeting & Expo, Seattle, Washington. May 11–14, 1997.     

Some metal compounds in the phase of crosslinked ionic polymer—precursors for new sorbents and catalysts

A commercial crosslinked ionic polymer AV‐17 containing ? N(CH₃)₃Cl groups was used. The common compounds of Bi(III) and Al(III); Bi(III) and Cr(III); Bi(III) and Fe(III); Bi(III) and FeOOH and of three components—Bi(III), Fe(III), and Cr(III); Bi(III), FeOOH, and Cr(III) were obtained in the AV‐17 polymer phase and investigated using scanning electron microscopy, powder X‐ray diffraction, thermogravimetric analysis, and Fourier‐transform infrared spectroscopy. It was shown that metal‐containing compounds were concentrated on the surface of the polymer granules. The compounds were in the crystalline (BiOCl) or amorphous (jarosites and oxihydroxides) state. The morphology and composition of the metal‐containing ultra dispersed particles were different on the surface and in the volume of the polymer granule. Most of the metal‐containing compounds were in the form of pseudo spherical particles, but compounds containing Bi(III) and FeOOH in the volume of AV‐17 granule, were in the form of clew of nanometer fibers. Thermogravimetric analysis (in an N₂ atmosphere) in the range 24–1000°C of the metallic compounds containing polymer was also carried out. The metal‐containing polymer samples were stable up to 120°C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Fluorescent Probe DCVJ Shows High Sensitivity for Characterization of Amyloid β-Peptide Early in the Lag Phase

The aggregation of intrinsically disordered and misfolded proteins in the form of oligomers and fibrils plays a crucial role in a number of neurological and neurodegenerative diseases. Currently, most probes and biophysical techniques that detect and characterize fibrils at high resolution fail to show sensitivity and binding for oligomers. Here, we show that 9-(dicyano-vinyl)julolidine (DCVJ), a class of molecular rotor, binds amyloid beta (Aβ) early aggregates, and we report the kinetics as well as packing of the oligomer formation. The binding of DCVJ to Aβ40 increased its emission intensity with time at 510 nm and produced a second excimer peak at 575 nm. However, DCVJ did not bind to the prefibrillar aggregates of Aβ42, which indicated that the oligomers formed by Aβ40 and Aβ42 were not the same. The F4C F19W mutant of Aβ40, which did not form fibrils, also bound DCVJ, but the emission spectral profile varied from that of the wild-type (WT). Atomic force microscopy images of WT Aβ40, the F4C F19W mutant, and Aβ42 oligomers displayed differences in size and shape, confirming the difference in their DCVJ spectra. The effect of epigallocatechin-3-gallate (EGCG) on the reduction of Aβ42 fibrils was also observed with finer detail than with other techniques. The results of this study show that DCVJ detects early aggregates and provides valuable information regarding the oligomer kinetics, packing, and mechanism of formation.     

Enzymatic Addition of Alcohols to Terpenes by Squalene Hopene Cyclase Variants

Squalene–hopene cyclases (SHCs) catalyze the polycyclization of squalene into a mixture of hopene and hopanol. Recently, amino-acid residues lining the catalytic cavity of the SHC from Alicyclobacillus acidocaldarius were replaced by small and large hydrophobic amino acids. The alteration of leucine 607 to phenylalanine resulted in increased enzymatic activity towards the formation of an intermolecular farnesyl–farnesyl ether product from farnesol. Furthermore, the addition of small-chain alcohols acting as nucleophiles led to the formation of non-natural ether-linked terpenoids and, thus, to significant alteration of the product pattern relative to that obtained with the wild type. It is proposed that the mutation of leucine at position 607 may facilitate premature quenching of the intermediate by small alcohol nucleophiles. This mutagenesis-based study opens the field for further intermolecular bond-forming reactions and the generation of non-natural products.     

Concept for a Hydrometallurgical Processing of a Copper-Cobalt-Nickel Alloy Made from Manganese Nodules

The processing of manganese nodules for the production of raw materials has been a subject of research for many decades. The nodules contain many valuable metals like copper, cobalt and nickel. In recent years, the German Federal Institute for Geoscience and Natural Resources developed a process for the processing of manganese nodules based on a combined pyro- and a hydrometallurgical route. Clausthal University of Technology was assigned to develop the hydrometallurgical process for the treatment of a FeNiCuCo alloy. The developed process consists of pressurized sulfuric acid leaching with the suppression of hydrogen gas formation, precipitation and solvent extraction.     

Platinum(II) Complexes Bearing Triphenylphosphine and Chelating Oximes: Antiproliferative Effect and Biological Profile in Resistant Cells

Platinum(II) complexes of the type [Pt(Cl)(PPh₃){(κ²-N,O)-(1{C(R)=N(OH)-2(O)C₆H₄})}] with R=Me, H, ( 1 and 2 ) were synthesized and characterized. Single-crystal X-ray diffraction confirmed the proposed (SP4-3) configuration for 1 . Study of the antiproliferative activity, performed on a panel of human tumor cell lines and on mesothelial cells, highlighted complex 2 as the more effective. In particular, it showed a remarkable cytotoxicity in ovarian carcinoma cells (A2780) and interestingly, a significant antiproliferative effect on cisplatin resistant cells (A2780cis). Investigation into the intracellular mechanism of action demonstrated that 2 had a lower ability to platinate DNA than did cisplatin, which was taken as reference, and a notably higher uptake in resistant cells. A significant accumulation in mitochondria, along with the ability to induce concentration-dependent mitochondrial membrane depolarization and intracellular reactive oxygen species production, allowed us to propose a mitochondrion-mediated pathway as responsible for the interesting cytotoxic profile of complex 2 .     

A Dual Inhibitor of DYRK1A and GSK3β for β-Cell Proliferation: Aminopyrazine Derivative GNF4877

Loss of β-cell mass and function can lead to insufficient insulin levels and ultimately to hyperglycemia and diabetes mellitus. The mainstream treatment approach involves regulation of insulin levels; however, approaches intended to increase β-cell mass are less developed. Promoting β-cell proliferation with low-molecular-weight inhibitors of dual-specificity tyrosine-regulated kinase 1A (DYRK1A) offers the potential to treat diabetes with oral therapies by restoring β-cell mass, insulin content and glycemic control. GNF4877, a potent dual inhibitor of DYRK1A and glycogen synthase kinase 3β (GSK3β) was previously reported to induce primary human β-cell proliferation in vitro and in vivo. Herein, we describe the lead optimization that lead to the identification of GNF4877 from an aminopyrazine hit identified in a phenotypic high-throughput screening campaign measuring β-cell proliferation.