Toward High‐Dimensional Single‐Cell Analysis of Graphene Oxide Biological Impact: Tracking on Immune Cells by Single‐Cell Mass Cytometry

Considering the potential exposure to graphene, the most investigated nanomaterial, the assessment of the impact on human health has become an urgent need. The deep understanding of nanomaterial safety is today possible by high‐throughput single‐cell technologies. Single‐cell mass cytometry (cytometry by time‐of flight, CyTOF) shows an unparalleled ability to phenotypically and functionally profile complex cellular systems, in particular related to the immune system, as recently also proved for graphene impact. The next challenge is to track the graphene distribution at the single‐cell level. Therefore, graphene oxide (GO) is functionalized with AgInS₂ nanocrystals (GO–In), allowing to trace GO immune–cell interactions via the indium (¹¹⁵In) channel. Indium is specifically chosen to avoid overlaps with the commercial panels (>30 immune markers). As a proof of concept, the GO–In CyTOF tracking is performed at the single‐cell level on blood immune subpopulations, showing the GO interaction with monocytes and B cells, therefore guiding future immune studies. The proposed approach can be applied not only to the immune safety assessment of the multitude of graphene physical and chemical parameters, but also for graphene applications in neuroscience. Moreover, this approach can be translated to other 2D emerging materials and will likely advance the understanding of their toxicology.     

Impact modified polyamide‐6/organoclay nanocomposites: Processing and characterization

The effects of melt state compounding of ethylene‐butyl acrylate‐maleic anhydride (E‐BA‐MAH) terpolymer and/or three types of organoclays (Cloisite® 15A, 25A, and 30B) on thermal and mechanical properties and morphology of polyamide‐6 are investigated. E‐BA‐MAH formed spherical domains in the materials to which it is added, and increased the impact strength, whereas the organoclays decreased the impact strength. In general, the organoclays increased the tensile strength (except for Cloisite 15A), Young's modulus and elongation at break, but the addition of E‐BA‐MAH had the opposite effect. XRD patterns showed that the interlayer spacing for the organoclays Cloisite 25A and Cloisite 30B increased in both polyamide‐6/organoclay binary nanocomposites and in polyamide‐6/organoclay/impact modifier ternary systems. TEM analysis showed that exfoliated‐intercalated nanocomposites were formed. The crystallinities of polyamide‐6/organoclay nanocomposites were in general lower than that of polyamide‐6 (except for Cloisite 15A). In ternary nanocomposites, crystallinities generally were lower than those of polyamide‐6/organoclay nanocomposites. Cloisite 15A containing ternary nanocomposites had higher tensile and impact strengths and Young's modulus than the ternary nanocomposites prepared with Cloisite 25A and Cloisite 30B, owing to its surface hydrophobicity and compatibility with the impact modifier. POLYM. COMPOS., 2008. © 2007 Society of Plastics Engineers     

Occurrence of disinfection by-products in low DOC surface waters in Turkey

A total of 29 surface waters from different regions of Turkey were sampled once a month during 2004. Filtered raw water samples were characterized, chlorinated and the concentrations of disinfection by-products (DBPs) were measured. All waters were low in DOC ranging from 0.91 to 4.42 mg/L. The range of annual average trihalomethanes (THMs) and haloacetic acids (HAAs) concentrations in all waters was 21-189 and 18-149mug/L, respectively. Total mass contributions of halides in THMs and HAAs to absorbable organic halides (AOX) ranged between 10 and 56% in all waters on annual average basis, indicating that significant amounts of other DBPs are being formed in the majority of the tested waters. A strong linear correlation was obtained between the concentrations of THMs and HAAs. Rather poor correlations were found for THMs-AOX and HAAs-AOX levels. For both THMs and HAAs, chlorinated species dominated over brominated ones since the majority of water sources had very low bromide levels. While chloroform and trichloroacetic acid were the major THM and HAA compounds, respectively; the extent of formation and speciation of DBPs varied greatly by season and water source. No consistent general trends were observed in terms of seasonal variations in DBP levels, suggesting that the characteristics of NOM moieties and their chlorine reactivity vary by season in almost all waters tested.     

Improving functionality of whole egg powder by the addition of gelatine, lactose, and pullulan

The addition of gelatine (G), lactose (L), pullulan (P), and their mixtures at equal ratios (gelatine + lactose [GL] and gelatin + pullulan [GP]) to whole egg prior to drying was studied. Their effects on the functional properties (emulsion and gelling ability, water holding capacity of gel, foaming, color) and soluble protein content of spray dried egg powder during the 6 mo of storage at 20 °C and 50% relative humidity were investigated. It was demonstrated that the emulsion and foaming stability, water holding capacity of gel, and color change were significantly affected by the storage time, whereas storage time did not affect the strength of gel texture prepared by egg powders. Gelatine and pullulan improved the foaming stability and water holding capacity. Lactose caused a decrease in emulsion and foaming stability values. The maximum color change was observed for the plain egg powder, showing that mixing whole egg with carbohydrate- and/or protein-based additives before the drying process preserved the color of egg powder. Adding carbohydrate and/or protein caused significant changes in functional properties of egg powder.     

Effects of nucleating agent and processing conditions on the mechanical,thermal, and optical properties of biaxially oriented polypropylene films

The effects of nucleating agent, temperature of crystallization, and degree of machine direction (MD) orientation on the mechanical, optical, and thermal properties of biaxially oriented polypropylene (BOPP) films were investigated. Addition of nucleating agent improved only the initial tear resistance in the MD; however, the other mechanical and optical properties did not change appreciably. In the set of experiments in which the crystallization temperature was increased, the degree of crystallinity also increased. Thus, Young's modulus, yield stress, and tensile strength increased in both directions with higher degree of crystallinity. The yield strain did not change significantly, but the strain at break was higher. Although the initial tear resistance was smaller in both directions with increasing crystallization temperature, the tear propagation resistance did not change. In this case, haze and diffuse transmittance were slightly higher, but the total transmittance was constant. In the set of experiments in which the machine direction orientation was increased, the degree of crystallinity also became higher. Owing to the effects of higher crystallinity and higher MD orientation, the modulus, yield stress, and tensile strength increased, but the yield strain and tear propagation resistance did not significantly change in both directions.     

Prototypes for building applications based on thermoplastic composites containing mixed waste plastics

Automotive shredder residue (ASR) and a complex residue obtained as a by‐product in the tertiary recycling of nylon‐6 fibers from used carpets were evaluated as potential additives in thermoplastic composites to be used for building applications. Prototype blocks were prepared by the “intrusion” process using various ratios of the waste streams and low‐density polyethylene (LDPE) in the absence of compatibilizers. Hence, product morphologies and corresponding properties were largely controlled through processing. They were evaluated for their short‐term and longterm mechanical properties, flammability, thermal conductivity, and heavy‐metal and total organic carbon leaching characteristics. Encapsulation of the waste feedstock by LDPE during molding in a single‐screw extruder significantly reduced the leachable content. In an effort to further reduce the leachable content, the mixtures were processed in two stages by precompounding in adevolatilizing twin‐screw extruder prior to molding. In comparison to the as‐received wastes, improved homogenization decreased the leachable heavy‐metal content by at least 98%. The carpet residue feedstock consisting of polypropylene, styrene‐butadiene rubber and calcium carbonate appears to be an attractive low‐cost, high‐volume material with consistent properties and could be used as filler in thermoplastic composites. Comparison of their performance characteristics suggested that the carpet residue composites would be favored versus ASR composites as replacement of the wood thermal barrier components in a novel steel‐based stud assembly.     

Doxorubicin-Induced Autophagolysosome Formation Is Partly Prevented by Mitochondrial ROS Elimination in DOX-Resistant Breast Cancer Cells

Since its discovery, mitophagy has been viewed as a protective mechanism used by cancer cells to prevent the induction of mitochondrial apoptosis. Most cancer treatments directly or indirectly cause mitochondrial dysfunction in order to trigger signals for cell death. Elimination of these dysfunctional mitochondria by mitophagy could thus prevent the initiation of the apoptotic cascade. In breast cancer patients, resistance to doxorubicin (DOX), one of the most widely used cancer drugs, is an important cause of poor clinical outcomes. However, the role played by mitophagy in the context of DOX resistance in breast cancer cells is not well understood. We therefore tried to determine whether an increase in mitophagic flux was associated with the resistance of breast cancer cells to DOX. Our first objective was to explore whether DOX-resistant breast cancer cells were characterized by conditions that favor mitophagy induction. We next tried to determine whether mitophagic flux was increased in DOX-resistant cells in response to DOX treatment. For this purpose, the parental (MCF-7) and DOX-resistant (MCF-7dox) breast cancer cell lines were used. Our results show that mitochondrial reactive oxygen species (ROS) production and hypoxia-inducible factor-1 alpha (HIF-1 alpha) expression are higher in MCF-7dox in a basal condition compared to MCF-7, suggesting DOX-resistant breast cancer cells are prone to stimuli to induce a mitophagy-related event. Our results also showed that, in response to DOX, autophagolysosome formation is induced in DOX-resistant breast cancer cells. This mitophagic step following DOX treatment seems to be partly due to mitochondrial ROS production as autophagolysosome formation is moderately decreased by the mitochondrial antioxidant mitoTEMPO.     

Effect of different types of organoclays and compatibilizers on the properties of polystyrene‐based nanocomposites

Polystyrene/organoclay nanocomposites were prepared by melt intercalation in the presence of elastomeric impact modifiers. Three different types of organically modified montmorillonites; Cloisite® 30B, 15A, and 25A, were used as reinforcement, whereas poly [styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene] (SEBS‐g‐MA) and poly(ethylene‐b‐butyl acrylate‐b‐glycidyl methacrylate) (E‐BA‐GMA) elastomeric materials were introduced to act as impact modifier. Owing to its single aliphatic tail on its modifier and absence of hydroxyl groups, Cloisite® 25A displayed the best dispersion in the polystyrene matrix, and mostly delaminated silicate layers were obtained in the presence of SEBS‐g‐MA. This was attributed to the higher viscosity of SEBS‐g‐MA compared with both E‐BA‐GMA and poly(styrene‐co‐vinyloxazolin) (PS). In addition, the compatibility between SEBS‐g‐MA and PS was found to be better in comparison to the compatibility between E‐BA‐GMA and PS owing to the soluble part of SEBS‐g‐MA in PS. The clay particles were observed to be located mostly in the dispersed phase leading to larger elastomeric domains compared with binary PS/elastomer blends. The enlargement of the elastomeric domains resulted in higher impact strength values in the presence of organoclay. Good dispersion of Cloisite® 25A in PS/SEBS‐g‐MA blends enhanced the tensile properties of this nanocomposite produced. It was observed that the change in the strength and stiffness of the ternary nanocomposites mostly depend on the type of the elastomeric material. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Dilatancy of concentrated suspensions with Newtonian matrices

Suspensions filled close to their maximum packing fraction present special challenges in their processing and in their rheological characterization. In this report, the literature in the area of dilatancy of concentrated suspensions is reviewed. Furthermore, the shear viscosity of a Newtonian polymeric liquid filled with 60 vol. percent of ammonium sulfate has been investigated. Both capillary and parallel disk torsional flows, were employed, spanning three decades in shear stress. Upon correction for slip, the suspension exhibited shear thinning at low shear stresses and shear thickening at higher shear stresses. Above a critical wall shear stress, the shear viscosity of the suspension increased unboundedly and the flow became pluglike with apparent slip at the wall. These findings have important ramifications in the processing of composites from such concentrated suspensions.     

Viscosity and die swell of acrylonitrile-butadiene-styrene filled with glass beads and glass fibers

Shear viscosity and die swell ratio of acrylonitrile-butadiene-styrene filled with glass beads and glass fibers were measured. The relative viscosity of the composites increased with filler content, but decreased with shear rate. At low shear rates, fiber filled systems had higher relative viscosities than bead filled systems. At high shear rates, the opposite was observed. The die swell ratio of the unfilled material increased linearly with the logarithm of the shear rate. Systems highly filled with glass beads or fibers showed a maximum in the die swell ratio at medium shear rates. The magnitude of the maximum in the die swell ratio increased with the filler content and the die length, up to a certain length, in a series of dies that had the same radius. The presence of a maximum in the die swell ratio of the filled melts is explained by an order-disorder phenomenon observed earlier by Wu.