Tailoring the properties of deposited thin coating and print features in flexography by application of UV-ozone treatment

Printed functional materials are a rapidly growing area of interest for low-cost high-speed device manufacture with flexographic printing seen as a route to achieving this. The relationship between surface tension of the ink and surface free energy (SFE) of the photopolymer plate is a key for optimum performance. However, traditional methods of surface tension modification of the ink/coating often cannot be employed for functional inks. In this research, rapid, permanent modification of flexographic printing plate’s SFE is achieved through controlled UV-ozone treatment, and the effects of the treatment on the polar and dispersive component of SFE are analyzed by Fourier transform infrared attenuated total reflectance spectroscopy, swelling experiments, and roughness measurements. Printing trials using the modified printing plates reveal improved print uniformity and control of deposited ink layer thickness, as well as improved print features—particularly track and pad junctions which can be problematic for printed electronic applications. The ability to rapidly tailor printing plate SFE is of benefit to all volume printing applications. Furthermore, it is of critical importance for functional printing and printed electronics where surface tension of the ink is determined by the functional material and chemical modification is not possible or desirable.     

Ketonization of Proline Residues in the Peptide Chains of Actinomycins by a 4‐Oxoproline Synthase

X‐type actinomycins (Acms) contain 4‐hydroxyproline (Acm X₀) or 4‐oxoproline (Acm X₂) in their β‐pentapeptide lactone rings, whereas their α ring contains proline. We demonstrate that these Acms are formed through asymmetric condensation of Acm half molecules (Acm halves) containing proline with 4‐hydroxyproline‐ or 4‐oxoproline‐containing Acm halves. In turn, we show—using an artificial Acm half analogue (PPL 1) with proline in its peptide chain—their conversion into the 4‐hydroxyproline‐ and 4‐oxoproline‐containing Acm halves, PPL 0 and PPL 2, in mycelial suspensions of Streptomyces antibioticus. Two responsible genes of the Acm X biosynthetic gene cluster of S. antibioticus, saacmM and saacmN, encoding a cytochrome P450 monooxygenase (Cyp) and a ferredoxin were identified. After coexpression in Escherichia coli, their gene products converted PPL 1 into PPL 0 and PPL 2 in vivo as well as in situ in permeabilized cell of the transformed E. coli strain in conjunction with the host‐encoded ferredoxin reductase in a NADH (NADPH)‐dependent manner. saAcmM has high sequence similarity to the Cyp107Z (Ema) family of Cyps, which can convert avermectin B1 into its keto derivative, 4′′‐oxoavermectin B1. Determination of the structure of saAcmM reveals high similarity to the Ema structure but with significant differences in residues decorating their active sites, which defines saAcmM and its orthologues as a distinct new family of peptidylprolineketonizing Cyp.     

Chemical curing of alkyd resin catalyzed by benzoylferrocene: Performance,kinetics, and thickness effects

Catalytic properties of benzoylferrocene, as a representative of cobalt‐free drier, was investigated on alkyd resin modified with soybean oil. Mechanical tests, performed on alkyd films, revealed promising activity at low metal concentrations. A detailed analysis of time resolved infrared spectra was used for in‐depth investigation of chemical curing in the films. The experiments, performed in transmission mode, enabled determination of kinetic parameters for the autoxidation process. Effects of film thickness were investigated using attenuated total reflectance technique. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46184.     

Lipid peroxidative damage on Cisplatin exposure and alterations in antioxidant defense system in rat kidneys: a possible protective effect of selenium

Cisplatin (Cis-diamminedichloroplatinum II, CP) is an important chemotherapeutic agent, useful in the treatment of several cancers, but with several side effects such as nephrotoxicity. The present study investigated the possible protective effect of selenium (Se) against CP-induced oxidative stress in the rat kidneys. Male Wistar albino rats were injected with a single dose of cisplatin (7 mg CP/kg b.m., i.p.) and selenium (6 mg Se/kg b.m, as Na(2)SeO(3), i.p.), alone or in combination. The obtained results showed that CP increased lipid peroxidation (LPO) and decreased reduced glutathione (GSH) concentrations, suggesting the CP-induced oxidative stress, while Se treatment reversed this change to control values. Acute intoxication of rats with CP was followed by statistically significant decreased activity of antioxidant defense enzymes: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR) and glutathione-S-transferase (GST). Treatment with Se reversed CP-induced alterations of antioxidant defense enzyme activities and significantly prevented the CP-induced kidney damage.     

Antiproliferative and Proapoptotic Activities of Methanolic Extracts from Ligustrum vulgare L. as an Individual Treatment and in Combination with Palladium Complex

The aim of this study is to examine the growth inhibitory effects of methanolic leaf and fruit extracts of L. vulgare on HCT-116 cells over different time periods and their synergistic effect with a Pd(apox) complex. The antiproliferative activity of plant extracts alone or in combination with the Pd(apox) complex was determined using MTT cell viability assay, where the IC(50) value was used as a parameter of cytotoxicity. Results show that antiproliferative effects of L. vulgare extracts increase with extension of exposure time, with decreasing IC(50) values, except for 72 h where the IC(50) values for methanolic leaf extract were lower than for the fruit extract. The Pd(apox) complex alone had a weak antiproliferative effect, but combination with L. vulgare extracts caused stronger effects with lower IC(50) values than with L. vulgare extracts alone. The type of cell death was explored by fluorescence microscopy using the acridin orange/ethidium bromide method. Treatments with plant extracts caused typical apoptotic morphological changes in HCT-116 cells and co-treatments with Pd(apox) complex caused higher levels of apoptotic cells than treatment with plant extracts alone. The results indicate that L. vulgare is a considerable source of natural bioactive substances with antiproliferative activity on HCT-116 cells and which have a substantial synergistic effect with the Pd(apox) complex.     

Bi2Ti2O7‐based pyrochlore nanoparticles and their superior photocatalytic activity under visible light

Nanoparticles of Bi₂Ti₂O₇ pyrochlore were synthesized by a coprecipitation method. They exhibit a high visible‐light photoactivity for decolorization of a methyl‐orange dye solution in the presence of a sacrificial agent, H₂O₂. The same pyrochlore system with an Ag co‐catalyst showed even faster kinetics under only visible light and an unprecedentedly high photoactivity in the UV range.     

CO2 laser-assisted preparation of transparent Eu2Ti2O7 thin films

We present a laser-assisted preparation of transparent europium-titanate Eu₂Ti₂O₇ thin films with tailored structural and optical properties. We have evaluated the effects of the irradiation time on the structural and the optical properties of the films. This approach allows the preparation of nanocrystalline crack-free films and micro patterns. The amorphous thin films were prepared by a sol-gel method. The films were annealed by a CO₂ laser beam for various time intervals. The laser irradiation induced a crystallization process that resulted in the formation of Eu₂Ti₂O₇ nanocrystals. The nanocrystals regularly grew with increasing irradiation time reaching the size from 25?nm to 45?nm. A film of a thickness 480?nm exhibited an optical transmission of 91.9% that is close to the maximal theoretical limit. The film's refractive index at 632?nm was 2.26. A micrometric pattern was prepared by a direct laser writing followed by a wet chemical etching. Feasibility of the demonstrated approach, together with the high film's quality, and europium-titanate chemical resistivity open up many opportunities for advanced applications. The approach can be used for a preparation of protective coatings and integrated photonic devices such as planar optical waveguides and couplers.     

Synthesis and properties of YBa2Cu3O7-δ – Y2Ba4CuWO10.8 superconducting composites

YBa₂Cu₃O_7-δ (YBCO) is a well-known high-temperature superconductor. However, its critical current density and thus maximum trapped magnetic field can be improved significantly by introducing the secondary phases (artificial pinning centers). In this contribution, we successfully prepared YBCO single-grain bulks with Y₂Ba₄CuWO_10.8 phase serving as a source of pinning centers. This phase was prepared by solid-state reaction and further refined by milling. In the next step single-grain YBCO bulks with homogeneously distributed Y₂Ba₄CuWO_10.8 were prepared by top-seeded melt growth. Precursors as well as the final product were characterized by XRD, SEM and EDS. The phase composition of YBCO bulks containing Y₂Ba₄CuWO_10.8 was analyzed using Rietveld analysis. Thermal stability of YBCO bulk was studied by STA. Furthermore, PPMS was used to study electrical resistivity and critical current density. Bulk superconducting properties such as levitation force and trapped field ability were also measured.     

Stereometric analysis of nanostructured boehmite coatings synthesized by aluminum nitride powder hydrolysis

We studied the morphological properties of precipitated, nanostructured, boehmite coatings on a polished alumina surface by exploiting the aluminum nitride (AlN) powder hydrolysis at elevated temperatures. The hydrolysis tests of the 3 wt% AlN powder suspensions in the temperature range 50–90 °C were performed in order to estimate the time needed for the synthesis of the coatings. They consisted of interlocked boehmite lamellas, positioned perpendicularly to the ceramic surface, and they exhibited a strong temperature-dependent size and surface density. The aim of this research was a quantitative assessment of the as-formed boehmite coatings. Based on electron microscopy micrographs, a stereometric analysis of the as-prepared coatings was performed in order to estimate the relevant geometric parameters of the lamellas. In spite of the temperature-dependent lamellas’ size and surface density, the specific volume of the coatings was similar for all the synthesis temperatures.