A Simple Route to Porous Graphene from Carbon Nanodots for Supercapacitor Applications

A facile method to convert biomolecule‐based carbon nanodots (CNDs) into high‐surface‐area 3D‐graphene networks with excellent electrochemical properties is presented. Initially, CNDs are synthesized by microwave‐assisted thermolysis of citric acid and urea according to previously published protocols. Next, the CNDs are annealed up to 400 °C in a tube furnace in an oxygen‐free environment. Finally, films of the thermolyzed CNDs are converted into open porous 3D turbostratic graphene (3D‐ts‐graphene) networks by irradiation with an infrared laser. Based upon characterizations using scanning electron microscopy, transmission electron microscopy, X‐ray photoelectron spectroscopy, X‐ray diffraction, Fourier‐transform infrared spectroscopy, and Raman spectroscopy, a feasible reaction mechanism for both the thermolysis of the CNDs and the subsequent laser conversion into 3D‐ts‐graphene is presented. The 3D‐ts‐graphene networks show excellent morphological properties, such as a hierarchical porous structure and a high surface area, as well as promising electrochemical properties. For example, nearly ideal capacitive behavior with a volumetric capacitance of 27.5 mF L ^{? 1} is achieved at a current density of 560 A L ^{? 1}, which corresponds to an energy density of 24.1 mWh L ^{? 1} at a power density of 711 W L ^{? 1}. Remarkable is the extremely fast charge–discharge cycling rate with a time constant of 3.44 ms.     

Protein Corona Mediated Stealth Properties of Biocompatible Carbohydrate-based Nanocarriers

Carbohydrates possess ideal properties for the synthesis of biocompatible nanocarriers. Therefore, hydroxyethyl starch was chosen as building material to produce biodegradable nanocarriers allowing the encapsulation of drugs. A mandatory feature for the successful application of nanocarriers in drug delivery is to avoid non-specific uptake into macrophages. Todays’ gold standard is poly(ethylene glycol) (PEG) attached onto the surface of nanocarriers. As alternatives, we synthesize completely carbohydrate-based nanocarriers by functionalizing the surface with different sugar derivatives (hydroxyethyl starch, dextran, or glucose) via copper-free click reaction. Studying the interaction of sugar-modified nanocarriers and plasma proteins indicates a strong enrichment of adsorbed ‘stealth’ proteins (clusterin) which are also identified on PEGylated nanocarriers. Cellular uptake studies proved that there is no unspecific interaction between carbohydrate- modified nanocarriers and phagocytic cells, herby underlining the stealth properties.     

Posttraumatic Inflammation as a Key to Neuroregeneration after Traumatic Spinal Cord Injury

Pro- and anti-inflammatory cytokines might have a large impact on the secondary phase and on the neurological outcome of patients with acute spinal cord injury (SCI). We measured the serum levels of different cytokines (Interferon-γ, Tumor Necrosis Factor-α, Interleukin-1β, IL-6, IL-8, IL-10, and Vascular Endothelial Growth Factor) over a 12-week period in 40 acute traumatic SCI patients: at admission on average one hour after initial trauma; at four, nine, 12, and 24 h; Three, and seven days after admission; and two, four, eight, and twelve weeks after admission. This was done using a Luminex Performance Human High Sensitivity Cytokine Panel. SCI was classified using the American Spinal Injury Association (ASIA) Impairment Scale (AIS) at time of admission and after 12 weeks. TNFα, IL-1β, IL-6, IL-8, and IL-10 concentrations were significantly higher in patients without neurological remission and in patients with an initial AIS A (p < 0.05). This study shows significant differences in cytokine concentrations shown in traumatic SCI patients with different neurological impairments and within a 12-week period. IL-8 and IL-10 are potential peripheral markers for neurological remission and rehabilitation after traumatic SCI. Furthermore our cytokine expression pattern of the acute, subacute, and intermediate phase of SCI establishes a possible basis for future studies to develop standardized monitoring, prognostic, and tracking techniques.     

Comparison of stretched polycarbonate films produced on a stretching line and a stretching frame

Various methods can be used for the axial stretching of polycarbonate films. This article compares uniaxially stretched films, produced on a stretching line by the short‐gap method, with planar‐stretched films that were produced on a stretching frame. The process affects the mechanical properties in the stretching direction as well as transversely. Because the stretching technologies differ primarily in the contraction of the film width, an analysis of the mechanical properties in the transverse direction is of particular interest. POLYM. ENG. SCI., 54:1848–1857, 2014. © 2013 Society of Plastics Engineers     

Influence of laminate thickness reduction on the deformation mechanism of coextruded multilayered PC/PMMA films

The influence of the morphology of multilayered composites of poly(methyl‐methacrylate) (PMMA) and polycarbonate (PC) fabricated by layer multiplying coextrusion technique on their mechanical and especially their micromechanical deformation behavior was investigated. Electron microscopic studies revealed that the PC/PMMA multilayered composites have a well‐oriented, uniform, and continuous layered architecture. With decreasing layer thickness of each polymer in the composite, the elongation at break of the films was found to increase significantly which was correlated with a transition from a two‐component behavior (for single‐layer thickness of ≥8 μm) to an one‐component behavior (for single‐layer thickness of ≤250 nm). Rheo‐optical measurements using FTIR spectroscopy revealed that the molecular orientation during stretching of the PMMA phase remains unchanged for all the investigated films, whereas the PC orientation function decreases with decreasing layer thickness. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Experimental and Modelling Study of a Dual-Layer NH3 Slip Monolith Catalyst for Automotive SCR Aftertreatment Systems

The approach to the development of a chemically and physically consistent mathematical model of ASC dual-layer (SCR + PGM) washcoated monolith converters is herein presented. Steady-state and transient kinetic runs were performed over each one of the two ASC components (SCR and PGM) in the form of powders and also over the two mixed powdered catalysts, thus acquiring information on the interactions between the SCR and the PGM catalytic chemistries. Global kinetic models were fitted to the SCR and to the PGM catalyst data, and validated against experiments performed over both washcoated single-layered SCR and PGM monoliths and over a full dual-layer ASC honeycomb catalyst (SCR layer on top). It was found that the dual-layer (SCR + PGM) ASC architecture grants increased N₂ selectivities compared to a PGM-only washcoat.     

Synthesis and Crystal Structure of Na2Ba9Si20O50—An Intermediate Phase Along the Join Na2Si2O5‐BaSi2O5

Single crystals of Na₂Ba₉Si₂₀O₅₀ were obtained from solid state reactions performed along the join Na₂Si₂O₅‐BaSi₂O₅. The crystal structure has been determined from a data set collected at ambient temperatures and subsequently refined to a residual of R(|F|) = 0.0328 for 2211 independent reflections. The compound belongs to the group of phyllosilicates and adopts the monoclinic space group C2/m with the following lattice parameters: a = 39.111(3) Å, b = 7.6566(6) Å, c = 8.2055(6) Å, β = 97.319(6)°, V = 2437.2(3) Å³, Z = 2. Furthermore, weak one‐dimensional diffuse streaks running parallel to a* as well as a very small number of low intensity reflections at b*/3, indicating the presence of a superstructure, were observed. Basic buiding units are silicate layers parallel to (40‐1) which can be obtained from the condensation of single chains with a periodicity of four running along [010]. The sheets can be partitioned into two kinds of consecutive strips containing (i) a sequence of four‐ and eight‐membered rings and (ii) a four‐ring wide “zig‐zag shaped” unit consisting of exclusively six‐membered rings. The sodium and barium cations—distributed among six crystallographically independent positions—are sandwiched between subsequent layers and are linked to seven to nine nearest oxygen neighbors. The structure of Na₂Ba₉Si₂₀O₅₀ is closely related to that of K₂Ba₅Si₁₂O₃₀ and K₂Ba₇Si₁₆O₄₀, respectively. There are strong arguments that the previously claimed phase Na₄Ba₈Si₂₀O₅₀ is actually misinterpreted Na₂Ba₉Si₂₀O₅₀ and that the composition of the intermediate phase along the join Na₂Si₂O₅–BaSi₂O₅ is slightly different from that described in the literature.     

Stability of Anthocyanin‐Rich W/O/W‐Emulsions Designed for Intestinal Release in Gastrointestinal Environment

Abstract: Anthocyanins belong to the most important hydrophilic plant pigments. Outside their natural environment, these molecules are extremely unstable. Encapsulating them in submicron‐sized containers is one possibility to stabilize them for the use in bioactivity studies or functional foods. The containers have to be designed for a target release in the human gastrointestinal system. In this contribution, an anthocyanin‐rich bilberry extract was encapsulated in the inner aqueous phase of water‐in‐oil‐in‐water‐double emulsions. The physical stability as well as the release of free fatty acids and encapsulated, bioactive substances from the emulsions during an in vitro gastrointestinal passage were investigated. The focus was on the influence of emulsion microstructural parameters (for example, inner and outer droplet size, disperse phase content) and required additives (emulsifier systems), respectively. It could be shown that it is possible to stabilize anthocyanins in the inner phase of double emulsions. The release rate of free fatty acids during incubation was independent of the emulsifier used. However, the exterior (O/W)‐emulsifier has an impact on the stability of multiple emulsions in gastrointestinal environment and, thus, the location of release. Long‐chained emulsifiers like whey proteins are most suitable to transport a maximum amount of bioactive substances to the effective location, being the small intestine for anthocyanins. In addition, it was shown that the dominating release mechanism for entrapped matter was coalescence of the interior W₁‐droplets with the surrounding W₂‐phase. Practical Application: Microencapsulation of phytochemicals and bioactives is in the focus of functional food development. Here, the influence of matrix material, formulation, and structural parameters on stabilization and release of the molecules encapsulated has to be known for target product and process design. As the results are representative for hydrophilic active ingredients encapsulated in double emulsion systems a cross‐sectoral use in the pharmaceutical sector is possible.