The Influence of Interfacial Areas for Gas Absorption in the Presence of Solid Particles

The mass transfer is investigated for physical absorption of oxygen in water for varying interfacial areas as well as the influence of suspended glass beads and activated carbon. Under higher rotational speed, the volumetric mass transfer coefficient as well as the mass transfer coefficient values increase for all specific interfacial areas due to the changes in hydrodynamics. The configuration of the free gas‐liquid interface is of minor relevance. In the presence of glass beads, the mass transfer is reduced compared to physical adsorption, whereas an enhancement of the mass transfer can be observed in the presence of activated carbon. This indicates that the mobility of the gas‐liquid interface is the determining factor. The renewal of the fluid elements is increased by adsorption of surfactants on the surface of activated carbon, leading to an improved mass transport.     

Performance analysis of mixed ionic-electronic conducting cathodes in anode supported cells

The analysis of mixed ionic-electronic conducting (MIEC) cathodes with respect to operation temperature and time is essential for a target-oriented development of anode-supported solid oxide fuel cells (ASCs). This study tracks both issues by impedance spectroscopy on a high-performance cathode with the composition La_0.58Sr_0.4Co_0.2Fe_0.8O_3−δ (LSCF).A wide set of impedance spectra were sampled at 600, 750 and 900 °C over the entire operation time of 1000 h. The identification and quantification of the individual anodic and cathodic contributions to the polarization losses of an ASC were enabled by an appropriate equivalent circuit model. For this purpose, the impedance data sets were evaluated subsequently by (i) a DRT (distribution of relaxation times) analysis followed by (ii) a CNLS fit. The cathodic polarization resistance is attributed to the oxygen surface exchange and the bulk diffusion of oxygen ions and is described by a Gerischer element.The anodic polarization resistance is described by a Warburg element and two RQ elements according to physical origins. The thorough analysis of all data sets leads to the surprising outcome that the cathode degradation is most pronounced and moreover, increases with decreasing temperature. After 1000 h of operation, the cathode polarization resistance raised steeply from 0.012%/h at 900 °C over 0.28%/h at 750 °C to 1.49%/h at 600 °C. These latest findings will have far-reaching implications for the development of MIEC cathodes.     

Polypropylene/polyethylene blends as models for high‐impact propylene‐ethylene copolymers,part 2: Relation between composition and mechanical performance

The relation between composition and mechanical performance of a series of binary polyolefin blends was studied in this article. A fractionation of these model compounds with temperature rising elution fractionation (TREF) was applied to study the possibility to fractionate industrially relevant heterophasic polyolefin systems. The separation quality according to molecular structures or chemical composition was found to be good for most of the systems, but especially the separation of ethylene‐propylene random copolymer and high density polyethylene by TREF turned out to be difficult if not impossible. An extensive mechanical characterisation including the determination of brittle‐to‐ductile transition curves showed significant effects of modifier type and amount. Toughness effects can be related primarily to the modulus differences between modifier and matrix. Compatibility and particle size only have a secondary influence, but must be considered for a detailed interpretation of the mechanics of the investigated systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The Role of Interleukin-1-Receptor-Antagonist in Bladder Cancer Cell Migration and Invasion

Background: The interleukin-1-receptor antagonist IL1RA (encoded by the IL1RN gene) is a potent competitive antagonist to interleukin-1 (IL1) and thereby is mainly involved in the regulation of inflammation. Previous data indicated a role of IL1RA in muscle-invasive urothelial carcinoma of the bladder (UCB) as well as an IL1-dependent decrease in tissue barrier function, potentially contributing to cancer cell invasion. Objective: Based on these observations, here we investigated the potential roles of IL1RA, IL1A, and IL1B in bladder cancer cell invasion in vitro. Methods: Cell culture, real-time impedance sensing, invasion assays (Boyden chamber, pig bladder model), qPCR, Western blot, ELISA, gene overexpression. Results: We observed a loss of IL1RA expression in invasive, high-grade bladder cancer cell lines T24, UMUC-3, and HT1197 while IL1RA expression was readily detectable in the immortalized UROtsa cells, the non-invasive bladder cancer cell line RT4, and in benign patient urothelium. Thus, we modified the invasive human bladder cancer cell line T24 to ectopically express IL1RA, and measured changes in cell migration/invasion using the xCELLigence Real-Time-Cell-Analysis (RTCA) system and the Boyden chamber assay. The real-time observation data showed a significant decrease of cell migration and invasion in T24 cells overexpressing IL1RA (T24-IL1RA), compared to cells harboring an empty vector (T24-EV). Concurrently, tumor cytokines, e.g., IL1B, attenuated the vascular endothelial barrier, which resulted in a reduction of the Cell Index (CI), an impedance-based dimensionless unit. This reduction could be reverted by the simultaneous incubation with IL1RA. Moreover, we used an ex vivo porcine organ culture system to evaluate cell invasion capacity and showed that T24-IL1RA cells showed significantly less invasive capacity compared to parental T24 cells or T24-EV. Conclusions: Taken together, our results indicate an inverse correlation between IL1RA expression and tumor cell invasive capacity and migration, suggesting that IL1RA plays a role in bladder carcinogenesis, while the exact mechanisms by which IL1RA influences tumor cells migration/invasion remain to be clarified in future studies. Furthermore, we confirmed that real-time impedance sensing and the porcine ex vivo organ culture methods are powerful tools to discover differences in cancer cell migration and invasion.     

Kinetic Study of Heterogeneously Catalyzed Glucose Oxidation in a Stirred Cell

Liquid phase oxidation of glucose to gluconic acid using Bi promoted Pd catalysts was studied in a stirred cell. Gas‐liquid mass transfer limitations are observed at lower but not at higher rotational speeds. The conversion and the deactivation of the Pd catalyst depend on the O₂ concentration in the liquid phase. With decreasing glucose concentration, the reaction rate decreases leading to higher oxygen concentration in the liquid, which deactivates the catalyst due to over‐oxidation. Severe mass transfer limitations even at low Pd loadings could be attributed to intraparticle or liquid‐to‐solid mass transfer.     

Biocompatible and biodegradable alginate/poly(N‐isopropylacrylamide) hydrogels for sustained theophylline release

Mixed‐interpenetrated polymeric networks based on sodium alginate (ALG) and poly(N‐isopropylacryl amide) (PNIPAAm) covalently cross‐linked with N,N'‐methylenebisacrylamide are studied for their biocompatibility, nontoxicity, and biodegradability aiming their application in drug delivery. The presence of drug‐polymeric matrix interactions and the distribution of the drug in the polymeric network for theophylline‐loaded ALG/PNIPAAm hydrogels are also investigated by spectroscopic and microscopic methods. The quantitative evaluation of theophylline loaded hydrogels performed by NIR‐CI technique shows a better drug entrapment and a higher homogeneity of the samples with increased alginate content. The thermal behavior of the hydrogels is significantly modified by theophylline presence. The application of the ALG/PNIPAAm hydrogels as carriers for sustained drug release formulations was assessed by the theophylline release tests performed both by in vitro and in vivo studies. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40733.     

Upon the characterization of semi-synthetic hydrogels based on poly (NIPAM) inserted onto collagen sponge

The preparation of a semi-synthetic hydrogel based on poly(N-isopropyl acrylamide-co-diethylene glycol diacrylate) inserted onto a collagen porous membrane, it was previous presented. The synthesis of the hydrogels was performed through radical copolymerization of N-isopropyl acrylamide (NIPAM) with diethylene glycol diacrylate (DEGDA) also as crosslinking agent, using ammonium persulfate as initiator and N,N,N′,N′-tetramethylethylene diamine activator, and it was achieved in the presence of the collagen matrix. In this paper the thus prepared hydrogels are characterized by Differential Scanning Calorimetry, Scanning Electron Microscopy and for their swelling capacities. A kinetic model was studied to investigate the swelling mechanism of the semi-interpenetrated polymeric network. The swelling behavior was found dependent on the hydrogel composition and to the external stimuli such as temperature and pH of environment. This manner of acting recommends these materials as smart materials with potential applications in tissue engineering and pharmaceutical field as for example bioproducts carrier matrices.     

Low density polyethylene composites containing cellulose pulp fibers

Unbleached and bleached Kraft cellulose pulp fibers modified with a long chain carboxylic acid, i.e. oleic acid in cold plasma conditions have been used as reinforcements in low density polyethylene (LDPE). The purpose of the modification is to enhance the interfacial adhesion between cellulose and matrix and to increase the dispersability. Composites containing up to 10 wt.% of untreated and modified cellulose pulp fibers with LDPE were prepared by melt mixing. The samples were characterized by processing behavior, mechanical and rheological properties, SEM, contact angle measurements, TGA and DSC. It was found that when the modified pulp fibers were incorporated into composites matrix, most of the properties have been improved.     

Dipolar-modulated charge-doped trilayer organic semiconductor n-n heterojunction

A novel dipolar-modulated charge-doped trilayer n-n organic heterojunction with a bidirectional tunable energy band discontinuity is constructed. The rectifying mechanism of the trilayer is similar to the rectifying and inverse-rectifying characteristics from n-p and p-n junctions, respectively. Zero-bias optoelectronic behavior and persistent photoconductivity are discovered. These results show that what are viewed as technological hurdles in the development of an organic n-n heterojunction should, in fact, lead to a better approach in organic optoelectronics.