Polymeric Thioxanthones as Potential Anticancer and Radiotherapy Agents

Thioxanthone (TX) and its derivatives, which are widely used as photoinitiators in UV curing technology, hold promising research interest in biological applications. In particular, the use of TXs as anticancer agent has recently been manifested as an outstanding additional property of this class of molecules. Incorporation of TX molecules into specially designed polymers widens their practical use in such applications. In this study, two water‐soluble, biocompatible, and stable polymers, namely poly(vinyl alcohol) and poly(ethylene glycol), possessing TX moieties at the side chains and chain ends, respectively, are prepared and used as anticancer and radiotherapy agents. The findings confirm that both polymers are potential candidates for therapeutic agents as they possess useful features including water‐solubility, radiosensitizer effect, and anticancer activity in a polymeric scaffold.

     

Products of projections in von Neumann algebras

We describe the elements of von Neumann algebras which can be represented as products of orthogonal projections and idempotents, and estimate the minimal number of terms in the product.     

Electron transport in semiconducting nanoparticle and nanocluster carbon-polymer composites

The electron transport properties of two types of carbon-polyimide (C-PI) nanocomposite thin films have been evaluated. Conductive nanocomposites formed by incorporation of 30 nm carbon particles prior to polymer cross linking (ex situ formation) has been compared to high energy ion beam irradiation in situ formation of nanoscale carbon clusters within the polymer composite. Addition of carbon nanoparticles were able to reduce the resistivity by 13 orders of magnitude for 8 vol% carbon content. The irradiated in situ formed film showed a comparable resistivity to this 8% C-PI film. All the films exhibited negative temperature coefficient of resistance (NTCR) behaviour. While in the ex situ films the NTCR decreased progressively with increasing temperature above 350 K, the in situ film exhibited a constant NTCR value at ambient as well as elevated temperatures indicating that films formed by ion beam irradiation eliminate possible clustering of nanoparticles prior to crosslinking seen in the ex situ films. The optimum hop energies for the ex situ films ranged from 23.1 to 8.05 meV when carbon content increased from 1 to 8 vol% and the corresponding value for the in situ formed film was 34.94 meV. These films had appreciable NTCR values, and were evaluated for their thermistor behaviour as a class of material with potential for temperature sensing devices.     

Synthesis and optical properties of Gd2O3:Pr3+ phosphor particles

Spherical-shaped Gd₂O₃:Pr³⁺ phosphor particles were prepared with different concentrations of Pr³⁺ using the urea homogeneous precipitation method. The resulting Gd₂O₃:Pr³⁺ phosphor particles were characterized by X-ray diffraction, field emission scanning electron microscope, and photoluminescence spectroscopy. The effects of the Pr³⁺ doping concentration on the luminescent properties of Gd₂O₃:Pr³⁺ phosphors were investigated. Photoluminescence measurements revealed the Gd₂O₃:1?% Pr³⁺ phosphor particles to have the strongest emission. The luminescence properties of Gd₂O₃:Pr³⁺ particles are strongly affected by the phosphor crystallinity and X-ray diffraction measurements confirmed that the crystallinity of Gd₂O₃ cubic structure could be enhanced by increasing the firing temperature. The luminescent Gd₂O₃:Pr³⁺ phosphor particles have potential applications in areas, such as optical display systems, lamps and etc.     

Operator Ideals on Non-commutative Function Spaces

Suppose X and Y are Banach spaces, and \({{\mathcal{I}}}\) , \({{\mathcal{J}}}\) are operator ideals. compact operators). Under what conditions does the inclusion \({\mathcal{I}(X,Y) \subset \mathcal{J}(X,Y)}\) , or the equality \({\mathcal{I}(X,Y)\,=\,\mathcal{J}(X,Y)}\) , hold? We examine this question when \({\mathcal{I}, \mathcal{J}}\) are the ideals of Dunford–Pettis, strictly (co)singular, finitely strictly singular, inessential, or (weakly) compact operators, while X and Y are non-commutative function spaces. Since such spaces are ordered, we also address the same questions for positive parts of such ideals.     

Electrical characteristics of HTS/manganite double layers

Superconductor/ferromagnetic (SC/FM) Y₁Ba₂Cu₃O_7−δ /La_0.7Sr_0.3MnO₃ (YBCO/LSMO) double layers were prepared on LaAlO₃ substrates by magnetron sputtering and their electrical and microwave parameters were investigated at 77 K. In the theoretical plan, simple formulas for estimation of the sensitivity of the SC surface impedance to the concentration changes of normal charge carriers were proposed and the surface resistance R _S peculiarities of both SC and FM surfaces were described. Thinner YBCO/LSMO structure was characterized by lower SC parameters and higher surface resistance R _S at ∼ 4 GHz. The difference of R _S of sample SC surfaces was interpreted as due to a difference between the normal charge carrier densities in these samples. R _S of the FM surface was higher than that of the SC surface due to the microwave losses of the magnetic subsystem. A peak of the microwave losses, observed in the thicker double layer, was assumed to be caused by uniform FMR in the LSMO film. Presented at 5-th International Conference Solid State Surfaces and Interfaces, November 19–24, 2006, Smolenice Castle, Slovakia.     

New polymethacrylic nonlinear optical materials containing multichromophores in the side chain

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Quantum chemical calculation of exchange interactions in supramolecularly arranged N,N′‐dioxy‐2,6‐diazaadamantane organic biradical

Quantum mechanical exchange effects in purely organic N,N′‐dioxy‐2,6‐diazaadamantane biradical derivatives with promesogenic substituents have been studied. To determine intermolecular exchange energies, packing conditions of the radical core units in layered liquid crystalline phases are simulated using the Gaussian 09 program. The broken symmetry approach gives J ≈ 7 cm^?1 for intramolecular ferromagnetic exchange interactions between nitroxyl radical centers in one molecule. Both ferromagnetic and antiferromagnetic intermolecular interactions are possible in this kind of systems according to the obtained calculation results. Depending on the mutual positioning and orientation of molecules, the intermolecular antiferromagnetic exchange constant can reach a value of ?50 cm^?1, and the intermolecular ferromagnetic constant a value of 10 cm^?1. The simultaneous presence of intramolecular and intermolecular exchange between spin‐carrying centers in this kind of supramolecularly ordered multispin systems is favorable for the formation of magnetically interacting chains and two‐dimensional networks. © 2016 Wiley Periodicals, Inc.     

Bridging the Time Gap: A Copper/Zinc Oxide/Aluminum Oxide Catalyst for Methanol Synthesis Studied under Industrially Relevant Conditions and Time Scales

Long‐term stability of catalysts is an important factor in the chemical industry. This factor is often underestimated in academic testing methods, which may lead to a time gap in the field of catalytic research. The deactivation behavior of an industrially relevant Cu/ZnO/Al₂O₃ catalyst for the synthesis of methanol is reported over a period of 148 days time‐on‐stream (TOS). The process was investigated by a combination of quasi in situ and ex situ analysis techniques. The results show that ZnO is the most dynamic species in the catalyst, whereas only slight changes can be observed in the Cu nanoparticles. Thus, the deactivation of this catalyst is driven by the changes in the ZnO moieties. Our findings indicate that methanol synthesis is an interfacially mediated process between Cu and ZnO.