Properties and nanoscale structure of polypropylene‐layered double hydroxide composites prepared by compatibilizer‐free way

Polypropylene (PP) is the second most widespread commodity polyolefin. Even a small quantity of inorganic component is sufficient to achieve significant improvement of stiffness, strength, thermal stability, biodegradability, etc. The major drawback of inorgano‐organic composite materials is insufficient compatibility of the PP matrix with inorganic filler. A suitable choice of the layered double hydroxide‐modifying anion opens a possibility to obtain PP‐inorganic nanocomposites without a need to use compatibilizers like maleic anhydride grafted PP. The nanocomposites were prepared by melt blending in a twin‐screw mini‐extruder and characterized by dynamic mechanical thermal analysis, and electron microscopy. Nonpolar PP matrix mix uniformly with clay organophilized with functionalized surfactant acids, giving rise to composites with improved thermo‐mechanical properties. Influences of the anionic modifier and the filler content (2 or 5% w/w) on mechanical properties and nanoscale structure of the composites are discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2429–2438, 2013     

Subcellular localization and activity of gambogic acid

The natural product gambogic acid (GA) has shown significant potential as an anticancer agent as it is able to induce apoptosis in multiple tumor cell lines, including multidrug-resistant cell lines, as well as displaying antitumor activity in animal models. Despite the fact that GA has entered phase I clinical trials, the primary cellular target and mode of action of this compound remain unclear, although many proteins have been shown to be affected by it. By thorough analysis of several cellular organelles, at both the morphological and functional levels, we demonstrate that the primary effect of GA is at the mitochondria. We found that GA induces mitochondrial damage within minutes of incubation at low-micromolar concentrations. Moreover, a fluorescent derivative of GA was able to localize specifically to the mitochondria and was displaced from these organelles after competition with unlabeled GA. These findings indicate that GA directly targets the mitochondria to induce the intrinsic pathway of apoptosis, and thus represents a new member of the mitocans.     

Preparation of regularly structured nanotubular TiO2 thin films on ITO and their modification with thin ALD-grown layers

Nanotubular titanium dioxide thin films were prepared by anodization of titanium metal films evaporated on indium tin oxide (ITO) coated glass. A facile method to enhance the adhesion of the titanium film to the ITO glass was developed. An optimum thickness of 550 nm for the evaporated titanium was found to keep the film adhered to ITO during the anodization. The films were further modified by growing amorphous titania, alumina and tantala thin films conformally in the nanotubes by atomic layer deposition (ALD). The optical, electrical and physical properties of the different structures were compared. It was shown that even 5 nm thin layers can modify the properties of the nanotubular titanium dioxide films.     

Preterm Intraventricular Hemorrhage-Induced Inflammatory Response in Human Choroid Plexus Epithelial Cells

Following an intraventricular hemorrhage (IVH), red blood cell lysis and hemoglobin (Hb) oxidation with the release of heme can cause sterile neuroinflammation. In this study, we measured Hb derivates and cellular adhesion molecules ICAM-1 and VCAM-1 with cell-free miRNAs in cerebrospinal fluid (CSF) samples obtained from Grade-III and Grade-IV preterm IVH infants (IVH-III and IVH-IV, respectively) at multiple time points between days 0–60 after the onset of IVH. Furthermore, human choroid plexus epithelial cells (HCPEpiCs) were incubated with IVH and non-IVH CSF (10 v/v %) for 24 h in vitro to investigate the IVH-induced inflammatory response that was investigated via: (i) HMOX1, IL8, VCAM1, and ICAM1 mRNAs as well as miR-155, miR-223, and miR-181b levels by RT-qPCR; (ii) nuclear translocation of the NF-κB p65 subunit by fluorescence microscopy; and (iii) reactive oxygen species (ROS) measurement. We found a time-dependent alteration of heme, IL-8, and adhesion molecules which revealed a prolonged elevation in IVH-IV vs. IVH-III with higher miR-155 and miR-181b expression at days 41–60. Exposure of HCPEpiCs to IVH CSF samples induced HMOX1, IL8, and ICAM1 mRNA levels along with increased ROS production via the NF-κB pathway activation but without cell death, as confirmed by the cell viability assay. Additionally, the enhanced intracellular miR-155 level was accompanied by lower miR-223 and miR-181b expression in HCPEpiCs after CSF treatment. Overall, choroid plexus epithelial cells exhibit an abnormal cell phenotype after interaction with pro-inflammatory CSF of IVH origin which may contribute to the development of later clinical complications in preterm IVH.     

Automated RNA Isolation Using the Ambion RNAqueous™-96 Kit with the Packard MutiPROBEII HT Liquid Handling System

Automated isolation of total RNA from cultured cells was accomplished by adapting Ambion's solid-phase total RNA isolation kit, RNAqueous-96, for use with the MultiPROBE II liquid handling system from Packard Instruments.Cultured cells (HeLa S3 adherent cells and K562 cells in suspension) were lysed, DNase treated, washed, and then eluted from the 96-well filter plate.Total RNA recovered was analyzed for yield, intactness, purity, and ability to serve as a substrate for real-time RT-PCR.     

Effect of organoclay content on the rheology,morphology, and physical properties of polyolefin elastomers and their blends with polypropylene

The effect of onium‐ion exchanged montmorillonite clay (organoclay) on the rheology and physical properties of maleated ethylene–octene copolymer and ethylene–propylene rubber elastomers has been examined. The formation of a nanocomposite hybrid, containing substantial amounts of exfoliated clay, was accompanied by significant increases in the complex viscosity, elastic and loss moduli, and a narrowing of the region of linear viscoelasticity, attributed to both filler/polymer and filler/filler interactions. The properties of blends of these elastomers with polypropylene were dominated by the reinforced elastomeric matrix, into which the organoclay resided preferentially. The nanocomposite blends exhibited very fine morphologies, as well as a good balance of stiffness and ductility and enhanced thermal stability. POLYM. ENG. SCI., 46:1491–1501, 2006. © 2006 Society of Plastics Engineers     

Stress management: individual differences and determination of situations (review of studies)

Following the review of studies and their results, the author highlighted the main features of the stress managing process as a basis for taking necessary actions to combat an occupational stress and to ease its possible negative effect. The documented variability of the stress managing provides an opportunity for incorporating the training on how to cope with the stress into the "stress management" programmes at the work place. The relationship between the ways and styles of coping with stress in particular situations and personality traits, significant, however moderate, indicates certain preferences in coping with stress in different situations. Therefore, a certain degree of behavioral "stiffness" as well as an individual approach should be taken into consideration in setting training programmes. The situation-related variability of coping with stress requires distinction between various behavioral patterns in view of occupational situations, namely the kind of stress and the situation control. However, the distinction alone between given behaviours does not provide a sufficient basis for promoting relevant strategies of coping with stress, it is also necessary to evaluate their efficiency, applying various short- and long-term efficiency criteria. Strategies which prove to be efficient during a short period of time need not be efficient during a long period of time, and behaviours successful in one situation may fail in another one.     

Anisotropic mesh adaptation for the generalized Ambrosio–Tortorelli functional with application to brittle fracture

Quasi-static crack propagation in brittle materials is modeled via the Ambrosio–Tortorelli approximation. The crack is modeled by a smooth phase-field, defined on the whole computational domain. Since the crack is confined to a thin layer, the employment of anisotropic adapted grids is shown to be a really effective tool in containing computational costs. We extend the anisotropic error analysis, applied to the classical Ambrosio–Tortorelli approximation by Artina et al., to the generalized Ambrosio–Tortorelli functional, where a unified framework for several elasticity laws is dealt with as well as a non-convex fracture energy can be accommodated. After deriving an anisotropic a posteriori error estimator, we devise an algorithm which alternates optimization and mesh adaptation. Both anti-plane and plane-strain configurations are numerically checked.