Redox‐ and pH‐Responsive Cysteamine‐Modified Poly(aspartic acid) Showing a Reversible Sol–Gel Transition

Synthesis and characterization of a pH‐ and redox‐sensitive hydrogel of poly(aspartic acid) are reported. Reversible gelation and dissolution are achieved both in dimethylformamide and in aqueous medium via a thiol‐disulphide interconversion in the side chain of the polymers. Structural changes are confirmed by Raman microscopy and rheological measurements. Injectable aqueous solutions of thiolated poly(aspartic acid) can be converted into mechanically stable gels by oxidation, which can be useful for drug encapsulation and targeted delivery. Reduction‐facilitated release of an entrapped drug from disulphide cross‐linked hydrogels is studied.

     

Double diastereocontrol in bifunctional thiourea organocatalysis: iterative Michael-Michael-Henry sequence regulated by the configuration of chiral catalysts

The importance and reactivity consequences of the double diastereocontrol in noncovalent bifunctional organocatalysis were studied. The results suggest that the bifunctional thioureas can have synthetic limitations in multicomponent domino or autotandem catalysis. Nevertheless, we provided a means to exploit this behavior and used the configuration of the chiral catalyst as a control element in organo-sequential reactions.     

EDITORIAL 2021: Journal of Thermal Analysis and Calorimetry

Journal of Thermal Analysis and Calorimetry - In this article, the thermal analyses of heat pump systems using photovoltaic-thermal collectors are reviewed. Initially, the energy balance equations...     

Convergence rates for an inertial algorithm of gradient type associated to a smooth non-convex minimization

Mathematical Programming - We investigate an inertial algorithm of gradient type in connection with the minimization of a non-convex differentiable function. The algorithm is formulated in the...     

Comparing different reaction models for combustion kinetics of solid recovered fuel

Journal of Thermal Analysis and Calorimetry - Possible utilization of SRF (solid recovered fuel) in the energy industry is a widely investigated topic, because even though it is economically...     

Mimicking a Superoxide Dismutase (SOD) Enzyme by copper(II) and zinc(II)-complexes

Mimicking the Superoxide Dismutase Enzyme (SOD), several imidazolato-bridged copper(II)-zinc(II) complexes were prepared, characterised by IR spectroscopy and their SOD enzyme activity was determined. 2,2′-Bipyridine, 2,2′:6′,2″-terpyridine and tris(2-aminoethyl)amine molecules were used on both metal sides, as coordinating ligands. The complex, containing the 2,2′:6′,2″-terpyridine ligand on copper side has the smallest SOD activity, which indicates the importance of the rigidity of the copper complex in SOD activity.     

Structural and Optical Properties of Gold/Silica “Mushroom” Particles Prepared by Interfacial Templating

Complex shaped nanoparticles featuring structural or surface chemical patchiness are of special interest in both fundamental and applied research areas. This study reports the preparation and optical properties of gold/silica “mushroom” nanoparticles, where a gold particle is only partially covered by the silica cap. The synthetic approach allows precise control over the particle structure. The interfacial preparation method relies on partially embedding the gold particles in a polystyrene layer that masks the immersed part of the gold particle during silica shell growth from an aqueous solution. By adjusting sacrificial polystyrene film thickness and silica growth time, precise control over the coverage and cap thickness can be achieved. Correlative electron microscopy and single particle scattering spectroscopy measurements underline the high precision and reproducibility of the method. The good agreement between the measured and simulated single particle spectra supported by near‐field calculations indicates that the observed changes in the dipolar plasmon resonance are influenced by the extent of coverage of the gold core by the silica cap. The straightforward methods readily available for gold and silica surface modification using range of different (bio)molecules make these well‐defined nanoscale objects excellent candidates to study fundamental processes of programmed self‐assembly or application as theranostic agents.     

Mössbauer study of novel iron(II) complexes synthesized with Schiff bases

Novel [Fe(4-benzyl-2-hydroxyphenyl-propylidene)₂ethylene-diamine], and [Fe (2,4,6-trihydroxy-benzyl-4-metoxiphenyl-methylidene)₂ethylene-diamine] complexes were synthesized by reacting Fe^II salt with the indicated Schiff-base ligands. The compounds were characterized by⁵⁷Fe Mössbauer spectroscopy, FTIR, UV-VIS, TG-DTA-DTG, MS, AFM, XRD, cyclic voltammetry and biological activity measurements. 295 K and 78 K Mössbauer spectra revealed that iron is dominantly in high spin Fe^II state in both complexes while simultaneously a minor low spin Fe^II was also present in both complexes, furthermore a minor high spin Fe^III was observed in [Fe(2,4,6-trihydroxy-benzyl-4-metoxiphenyl- methylidene) ₂ethylene-diamine], too.     

Thermal properties of electrospun polyvinylpyrrolidone/titanium tetraisopropoxide composite nanofibers

Journal of Thermal Analysis and Calorimetry - In this work, polyvinylpyrrolidone/titanium tetraisopropoxide (PVP/TTIP) composite nanofibers were prepared by electrospinning from alcoholic...     

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