Dyes based on a 1,4‐naphthoquinone skeleton as new type II photoinitiators for radical polymerisation

Photoredox pairs consisting of 1,4‐naphthoquinone dyes and commercially available hydrogen donors (2‐mercaptobenzoxazole, 2‐mercaptobenzothiazole, 2‐mercaptobenzimidazole and 2,5‐dimercapto‐1,3,4‐thiadiazole) are found to be effective initiator systems for the radical polymerisation of trimethylolpropane triacrylate under visible light. The efficiency of these initiator systems is discussed in terms of the free energy change for the electron transfer process from the dye to the hydrogen donor. The results show that the photoinitiation ability of tested photoredox pairs depends on the structure of both the dye and the hydrogen donor.     

Photocrosslinking of solvent-based acrylic pressure-sensitive adhesives (PSA) by the use of selected photoinitiators type I

This study investigated the photocrosslinking of solvent-based acrylic pressure-sensitive adhesives (PSA) containing selected photoinitiators type I, known as α-cleavage photoinitiators. Photocrosslinking of PSA, especially of acrylic PSA, is well established crosslinking process using the UV radiation technology. UV-initiated crosslinking of acrylic PSA allows the synthesis of the wide range of UV-crosslinkable PSA with the interesting features. Especially, the important balances of properties such as adhesive and cohesive strength which are typically critical for the application performance can be achieved by this technology. The selection of suitable photoinitiator plays an important role to obtain the optimum properties of acrylic PSA including tack, peel adhesion, and shear strength. In this study, the investigations on different saturated conventional photoinitiators of type I for solvent-based PSA were carried out. The effects of photoinitiator concentration, UV crosslinking time and UV dose on the tack, peel strength, and shear strength were explored in detail for guiding the choice of photoinitiators to fabricate advanced PSA for industrial usage.     

Nickel-containing nano-sized islands grown on Ge(111)-c(2 × 8) and Ag/Ge(111)-(√3 × √3) surfaces

The formation of nano-islands on both a Ge(111)-c(2 × 8) surface and an Ag/Ge(111)-(√3 × √3) surface evaporated with 0.1 ML Ni was investigated by scanning tunneling microscopy (STM). We have noticed that at temperatures lower than 670 K, the reaction between Ni and the individual substrate surfaces proceeds to form different structures: flat-topped islands with a 2√7 × 2√7 or a 3 × 3 reconstruction on the Ni/Ge(111)-c(2 × 8) surface vs. islands with a 7 × 7 reconstruction on the Ni/Ag/Ge(111)-(√3 × √3) surface. From this we have inferred that within a temperature range between room temperature and 670 K, the intermediate Ag layer retards mixing between Ni and Ge atoms. As a result, the grown islands are composed of pure Ni atoms. Within a temperature range from 670 to 770 K, most islands produced on the Ag/Ge(111)-(√3 × √3) surface are identical with those formed on the Ni/Ge(111)-c(2 × 8) surface, suggesting that above 670 K, Ni atoms are likely to bind with Ge atoms. However, an essential difference between STM images of the surfaces under study exists in the appearance of large elongated islands on the Ni/Ag/Ge(111)-(√3 × √3) surface. The formation of the latter is explained in terms of a difference in energy for Ni diffusion on the Ge(111)-c(2 × 8) and Ag/Ge(111)-(√3 × √3) surfaces.     

The Combination of Intestinal Alkaline Phosphatase Treatment with Moderate Physical Activity Alleviates the Severity of Experimental Colitis in Obese Mice via Modulation of Gut Microbiota,Attenuation of Proinflammatory Cytokines,Oxidative Stress Biomarkers and DNA Oxidative Damage in Colonic Mucosa

Inflammatory bowel diseases (IBD) are commonly considered as Crohn’s disease and ulcerative colitis, but the possibility that the alterations in gut microbiota and oxidative stress may affect the course of experimental colitis in obese physically exercising mice treated with the intestinal alkaline phosphatase (IAP) has been little elucidated. Mice fed a high-fat-diet (HFD) or normal diet (ND) for 14 weeks were randomly assigned to exercise on spinning wheels (SW) for 7 weeks and treated with IAP followed by intrarectal administration of TNBS. The disease activity index (DAI), grip muscle strength test, oxidative stress biomarkers (MDA, SOD, GSH), DNA damage (8-OHdG), the plasma levels of cytokines IL-2, IL-6, IL-10, IL-12p70, IL-17a, TNF-α, MCP-1 and leptin were assessed, and the stool composition of the intestinal microbiota was determined by next generation sequencing (NGS). The TNBS-induced colitis was worsened in obese sedentary mice as manifested by severe colonic damage, an increase in DAI, oxidative stress biomarkers, DNA damage and decreased muscle strength. The longer running distance and weight loss was observed in mice given IAP or subjected to IAP + SW compared to sedentary ones. Less heterogeneous microbial composition was noticed in sedentary obese colitis mice and this effect disappeared in IAP + SW mice. Absence of Alistipes, lower proportion of Turicibacter, Proteobacteria and Faecalibacterium, an increase in Firmicutes and Clostridium, a decrease in oxidative stress biomarkers, 8-OHdG content and proinflammatory cytokines were observed in IAP + SW mice. IAP supplementation in combination with moderate physical activity attenuates the severity of murine colitis complicated by obesity through a mechanism involving the downregulation of the intestinal cytokine/chemokine network and oxidative stress, the modulation of the gut microbiota and an improvement of muscle strength.     

Evaluation of the Effects of Ag,Cu, ZnO and TiO2 Nanoparticles on the Expression Level of Oxidative Stress-Related Genes and the Activity of Antioxidant Enzymes in Escherichia coli,Bacillus cereus and Staphylococcus epidermidis

Although the molecular response of bacteria exposed to metal nanoparticles (NPs) is intensively studied, many phenomena related to their survival, metal uptake, gene expression and protein production are not fully understood. Therefore, this work aimed to study Ag-NPs, Cu-NPs, ZnO-NPs and TiO₂-NPs-induced alterations in the expression level of selected oxidative stress-related genes in connection with the activity of antioxidant enzymes: catalase (CAT), peroxidase (PER) and superoxide dismutase (SOD) in Escherichia coli, Bacillus cereus and Staphylococcus epidermidis. The methodology used included: the extraction of total RNA and cDNA synthesis, the preparation of primers for selected housekeeping and oxidative stress genes, RT-qPCR reaction and the measurements of CAT, PER and SOD activities. It was established that the treatment of E. coli and S. epidermidis with NPs resulted mainly in the down-regulation of targeted genes, whilst the up-regulation of genes was confirmed in B. cereus. The greatest differences in the relative expression levels of tested genes occurred in B. cereus and S. epidermidis treated with TiO₂-NPs, while in E. coli, they were observed under ZnO-NPs exposure. The changes found were mostly related to the expression of genes encoding proteins with PER and CAT-like activity. Among NPs, ZnO-NPs and Cu-NPs increased the activity of antioxidants in E. coli and B. cereus. In turn, TiO₂-NPs had a major effect on enzymes activity in S. epidermidis. Considering all of the collected results for tested bacteria, it can be emphasised that the impact of NPs on the antioxidant system functioning was dependent on their type and concentration.     

Thermal stability of poly(2-ethylhexyl acrylates) used as plasticizers for medical application

This article discusses thermal analysis of different molecular weight poly(2-ethylhexyl acrylates) synthesized by radical polymerization of 2-ethylhexyl acrylate. The main aim of this work was to investigate the thermal properties and degradation process of synthesized acrylic homopolymers and forming of thermal degradation products during their pyrolysis. As investigated method pyrolysis combined with gas chromatography was used. Poly(2-ethylhexyl acrylates) are used as plasticizers for pressure-sensitive adhesives applied in medical area.     

A Stochastic Petri Net-Based Model of the Involvement of Interleukin 18 in Atherosclerosis

Interleukin 18 (IL-18) is a proinflammatory and proatherogenic cytokine with pleiotropic properties, which is involved in T and NK cell maturation and the synthesis of other inflammatory cytokines and cell adhesion molecules. It plays a significant role in orchestrating the cytokine cascade, accelerates atherosclerosis and influences plaque vulnerability. To investigate the influence of IL-18 cytokine on atherosclerosis development, a stochastic Petri net model was built and then analyzed. First, MCT-sets and t-clusters were generated, then knockout and simulation-based analysis was conducted. The application of systems approach that was used in this research enabled an in-depth analysis of the studied phenomenon. Our results gave us better insight into the studied phenomenon and allow revealing that activation of macrophages by the classical pathway and IL-18-MyD88 signaling axis is crucial for the modeled process.