Influence of the environment on swelling of hydrophilic polymers

The influence of water activity on swelling of cross-linked hydrophilic polymers in electrolyte solutions of various concentrations was studied. A heterophase model was proposed to explain the polymer swelling. It was shown that the change in polymer swelling deals with different water sorption, and is described by water vapour sorption isotherm. At the same time, the volume of external solution taken up by polymer at swelling is constant and independent of concentration of the solution. Three models describing the structure of polymer gels were suggested and discussed on the base of the obtained results.     

In Situ Synthesis of Molybdenum Carbide Nanoparticles Incorporated into Laser-Patterned Nitrogen-Doped Carbon for Room Temperature VOC Sensing

Carbon laser-patterning (CLaP) is emerging as a new tool for the precise and selective synthesis of functional carbon-based materials for on-chip applications. The aim of this work is to demonstrate the applicability of laser-patterned nitrogen-doped carbon (LP-NC) for resistive gas-sensing applications. Films of pre-carbonized organic nanoparticles on polyethylenetherephthalate are carbonized with a CO₂-laser. Upon laser-irradiation a compositional and morphological gradient in the films is generated with a carbon content of 92% near the top surface. The specific surface areas of the LP-NC are increased by introducing sodium iodide (NaI) as a porogen. Electronic conductivity and surface area measurements corroborate the deeper penetration of the laser-energy into the film in the presence of NaI. Furthermore, impregnation of LP-NC with MoC_1−x (<10 nm) nanoparticles is achieved by addition of ammonium heptamolybdate into the precursor film. The resulting doping-sensitive nano-grain boundaries between p-type carbon and metallic MoC_1−x lead to an improvement of the volatile organic compounds sensing response of ΔR/R₀ = −3.7% or −0.8% for 1250 ppm acetone or 900 ppm toluene at room temperature, respectively, which is competitive with carbon-based sensor materials. Further advances in sensitivity and in situ functionalization are expected to make CLaP a useful method for printing selective sensor arrays.     

Calorie Restriction Provides Kidney Ischemic Tolerance in Senescence-Accelerated OXYS Rats

Kidney diseases belong to a group of pathologies, which are most common among elderly people. With age, even outwardly healthy organisms start to exhibit some age-related changes in the renal tissue, which reduce the filtration function of kidneys and increase the susceptibility to injury. The therapy of acute kidney injury (AKI) is aggravated by the absence of targeted pharmacotherapies thus yielding high mortality of patients with AKI. In this study, we analyzed the protective effects of calorie restriction (CR) against ischemic AKI in senescence-accelerated OXYS rats. We observed that CR afforded OXYS rats with significant nephroprotection. To uncover molecular mechanisms of CR beneficial effects, we assessed the levels of anti- and proapoptotic proteins of the Bcl-2 family, COX IV, GAPDH, and mitochondrial deacetylase SIRT-3, as well as alterations in total protein acetylation and carbonylation, mitochondrial dynamics (OPA1, Fis1, Drp1) and kidney regeneration pathways (PCNA, GDF11). The activation of autophagy and mitophagy was analyzed by LC3 II/LC3 I ratio, beclin-1, PINK-1, and total mitochondrial protein ubiquitination. Among all considered protective pathways, the improvement of mitochondrial functioning may be suggested as one of the possible mechanisms for beneficial effects of CR.     

A Novel Method of Mouse RPE Explant Culture and Effective Introduction of Transgenes Using Adenoviral Transduction for In Vitro Studies in AMD

Degeneration of retinal pigment epithelium (RPE) is one of the most critical phenotypic changes of age-related macular degeneration (AMD), the leading cause of vision loss in the elderly. While cultured polarized RPE cells with original properties are valuable in in vitro models to study RPE biology and the consequences of genetic and/or pharmacological manipulations, the procedure to establish mouse primary PRE cell culture or pluripotent stem cell-derived RPE cells is time-consuming and yields a limited number of cells. Thus, establishing a mouse in situ RPE culture system is highly desirable. Here we describe a novel and efficient method for RPE explant culture that allows for obtaining biologically relevant RPE cells in situ. These RPE explants (herein referred to as RPE flatmounts) are viable in culture for at least 7 days, can be efficiently transduced with adenoviral constructs, and/or treated with a variety of drugs/chemicals followed by downstream analysis of the signaling pathways/biological processes of interest, such as assessment of the autophagy flux, inflammatory response, and receptor tyrosine kinases stimulation. This method of RPE explant culture is highly beneficial for pharmacological and mechanistic studies in the field of RPE biology and AMD research.     

Effect of purification of carbon nanotubes on their electrocatalytic properties for oxygen reduction in acid solution

The oxygen reduction reaction has been investigated on acid-treated single-walled (SWCNT) and multi-walled carbon nanotubes (MWCNT) modified glassy carbon (GC) electrodes in acid media using the rotating disk electrode (RDE) method. Different acids were used for the carbon nanotube (CNT) purification. A systematic study was carried out to elucidate whether the metal catalyst impurities of CNTs play a role in the electroreduction of oxygen on the CNT modified GC electrodes. The surface morphology of the carbon nanotube samples was examined by transmission electron microscopy and the concentration of metal catalysts in the CNT materials was determined by energy dispersive X-ray spectroscopy. The acid-treated MWCNTs were also characterised by Raman and X-ray photoelectron spectroscopies. Aqueous suspensions of SWCNTs and MWCNTs used for GC surface modification were prepared in the presence of Nafion. The RDE results indicated that the acid-treated CNT modified GC electrodes are less active catalysts for oxygen reduction than as-received CNTs which could be explained by the absence of metal catalysts on the surface of purified CNTs.     

Is the Mitochondrial Membrane Potential (∆Ψ) Correctly Assessed? Intracellular and Intramitochondrial Modifications of the ∆Ψ Probe,Rhodamine 123

The mitochondrial membrane potential (∆Ψ) is the driving force providing the electrical component of the total transmembrane potential of hydrogen ions generated by proton pumps, which is utilized by the ATP synthase. The role of ∆Ψ is not limited to its role in bioenergetics since it takes part in other important intracellular processes, which leads to the mandatory requirement of the homeostasis of ∆Ψ. Conventionally, ∆Ψ in living cells is estimated by the fluorescence of probes such as rhodamine 123, tetramethylrodamine, etc. However, when assessing the fluorescence, the possibility of the intracellular/intramitochondrial modification of the rhodamine molecule is not taken into account. Such changes were revealed in this work, in which a comparison of normal (astrocytic) and tumor (glioma) cells was conducted. Fluorescent microscopy, flow cytometry, and mass spectrometry revealed significant modifications of rhodamine molecules developing over time, which were prevented by amiodarone apparently due to blocking the release of xenobiotics from the cell and their transformation with the participation of cytochrome P450. Obviously, an important role in these processes is played by the increased retention of rhodamines in tumor cells. Our data require careful evaluation of mitochondrial ∆Ψ potential based on the assessment of the fluorescence of the mitochondrial probe.     

The influence of organic and conventional crop management,variety and year on the yield and flavonoid level in common buckwheat groats

Common buckwheat (Fagopyrum esculentum Moench) is a pseudocereal that is cultivated for its achenes that possess a high level of flavonoids. Some scientific studies have found that the growing conditions can significantly affect the flavonoid content in conventional and organic food products. Hence, the present study compared conventionally and organically produced common buckwheat with respect to the content of selected flavonoids, thousand achenes weight and achene yield. Three buckwheat varieties were grown with organic and conventional crop management under the same environmental conditions. The thousand achenes weight and achene yield were not significantly influenced by way of crop management. The level of rutin, epicatechin, catechin, and epicatechin gallate in buckwheat groats (hulled achenes) were quantified with high pressure liquid chromatography. Only rutin and epicatechin gallate reached significantly higher level in organic groats. However, the differences were influenced by environmental conditions in the given year and variety.     

Characterization of the solidification path of AlSi5Cu(1–4 wt.%) alloys using cooling curve analysis

Available databases presently used by commercial simulation software packages for the aluminum casting industry usually come with material properties for only a few selected standard alloys. In the case of other alloys with different chemical compositions and refinement or modification treatment, thermal analysis could be an invaluable tool in order to gain necessary properties. The aim of this paper is to characterize the solidification paths of Al-Si5-Cu(1–4) alloys and quantify the amount of solid fraction using cooling curve analysis. The correlation between solid fraction and temperature has been determined using Newtonian and Fourier techniques of base line. Both techniques are also briefly described in this paper. The obtained results have been compared with results obtained using available commercial software (e.g., Pandat and JMatPro).     

Differential Object Marking in Kazakh: The Dynamic Syntax Approach

Journal of Logic, Language and Information - This paper presents a novel, Dynamic Syntax-based approach to the phenomenon of differential object marking in Kazakh, which can be extended at least to...