Einfluss einer PVD‐Al‐Zwischenschicht auf die Eigenschaften eines thermisch gespritzten Wärmedämmschichtsystems nach Temperaturwechselbelastung

Thermal barrier coatings (TBC) generally consist of a metallic bond coat (BC) and a ceramic top coat (TC). Co–Ni–Cr–Al–Y metallic super alloys and Yttria stabilised zirconia (YSZ) have been widely used as bond coat and top coat for thermal barrier coatings systems, respectively. As a result of long‐term exposure of thermal barrier coatings systems to oxygen‐containing atmospheres at high temperatures, a diffusion of oxygen through the porous ceramic layer occurs and consequently an oxidation zone is formed in the interface between ceramic top coat and metallic bond coat. Alloying components of the BC layer create a so‐called thermally grown oxides layer (TGO). One included oxide type is α‐Al₂O₃. α‐Al₂O₃ lowers oxygen diffusion and thus slows down the oxidation process of the bond coat and consequently affects the service life of the coating system positively. The distribution of the alloying elements in the bond coat layer, however, generally causes the formation of mixed oxide phases. The different oxide phases have different growth rates, which cause local stresses, micro‐cracking and, finally, delamination and failure of the ceramic top coat layer. In the present study, a thin Al inter‐layer was deposited by DC‐Magnetron Sputtering on top of the Co–Ni–Cr–Al–Y metallic bond coat, followed by thermal spraying of yttria‐stabilised zirconia (YSZ) as a top coat layer. The deposited Al inter‐layer is meant to transform under operating conditions into a closed layer with high share of α‐Al₂O₃ that slows down the growth rate of the resulting thermally grown oxides layer. Surface morphology and microstructure characteristics as well as thermal cycling behaviour were investigated to study the effect of the intermediate Al layer on the oxidation of the bond coat compared to standard system. The system with Al inter‐layer shows a smaller thermally grown oxides layer thickness compared to standard system after thermal cycling under same conditions.     

A reduced‐order representation of the Poincaré–Steklov operator: an application to coupled multi‐physics problems

This work investigates a model reduction method applied to coupled multi‐physics systems. The case in which a system of interest interacts with an external system is considered. An approximation of the Poincaré–Steklov operator is computed by simulating, in an offline phase, the external problem when the inputs are the Laplace–Beltrami eigenfunctions defined at the interface. In the online phase, only the reduced representation of the operator is needed to account for the influence of the external problem on the main system. An online basis enrichment is proposed in order to guarantee a precise reduced‐order computation. Several test cases are proposed on different fluid–structure couplings. Copyright © 2016 John Wiley & Sons, Ltd.     

Investigating the Hybrid‐Structure‐Effect of CeO2‐Encapsulated Au Nanostructures on the Transfer Coupling of Nitrobenzene

Due to the obvious distinctions in structure, core–shell nanostructures (CSNs) and yolk–shell nanostructures (YSNs) exhibit different catalytic behavior for specific organic reactions. In this work, two unique autoredox routes are developed to the fabrication of CeO₂‐encapsulated Au nanocatalysts. Route A is the synthesis of well‐defined CSNs by a one‐step redox reaction. The process involves an interesting phenomenon in which Ce³⁺ can act as a weak acid to inhibit the hydrolysis of Ce⁴⁺ under the condition of OH^? shortage. Route B is the fabrication of monodispersed YSNs by a two‐step redox reaction with amorphous Co₃O₄ as an in situ template. Furthermore, the transfer coupling of nitrobenzene is chosen as a probe reaction to investigate their catalytic difference. The CSNs can gradually achieve the conversion of nitrobenzene into azoxybenzene, while the YSNs can rapidly convert nitrobenzene into azobenzene. The different catalytic results are mainly attributed to their structural distinctions.     

Characterization of l‐polylactide and l‐polylactide–polycaprolactone co‐polymer films for use in cheese‐packaging applications

Impact‐modified and unmodified l ‐polylactide and l ‐polylactide–polycaprolactone co‐polymer films were evaluated for their suitability as materials for cheese packaging. The polymers were in some cases compounded with nanoclays as a possible route to enhanced barrier properties and/or with cyclodextrin complexes designed to provide slow release of encapsulated antimicrobials for control of mould growth on packaged cheeses. The materials demonstrated complete biodegradation under controlled composting conditions and the extruded films had acceptable transparency. Moisture uptake by films and a decrease in polymer molecular weight with time of exposure to high humidity were identified as areas of concern, although the polymer stability experiments were undertaken at 25°C and stability at normal cheese storage temperatures (～4°C) is expected to be better. Nanoclay addition enhanced the thermal stability of the polymer but reduction of oxygen and water vapour permeability to target levels through incorporation of 5% w/w nanoclay was not achieved, possibly in part due to inadequate dispersion of the nanoclays in the chosen polymer matrices. On the positive side, a novel impact‐modified polylactide was developed that overcame problems with brittleness in unmodified l ‐polylactide and l ‐polylactide–polycaprolactone co‐polymer films, and tests indicated that a cyclodextrin‐encapsulated antimicrobial (allyl isothiocyanate) incorporated in l ‐polylactide–polycaprolactone co‐polymer films would be effective in controlling fungi on packaged cheeses. Migration of substances from the l ‐polylactide or l ‐polylactide–polycaprolactone films into cheese is not expected to be a problem. Copyright © 2005 John Wiley & Sons, Ltd.     

An alternative TLM method for steady‐state convection–diffusion

Recent papers have introduced a novel and efficient scheme, based on the transmission line modelling (TLM) method, for solving one‐dimensional steady‐state convection–diffusion problems. This paper introduces an alternative method. It presents results obtained using both techniques, which suggest that the new scheme outlined in this paper is the more accurate and efficient of the two. Copyright © 2009 John Wiley & Sons, Ltd.     

Self‐Phosphorization of MOF‐Armored Microbes for Advanced Energy Storage

Utilization of microbes as the carbon source and structural template to fabricate porous carbon has incentivized great interests owing to their diverse micromorphology and intricate intracellular structure, apart from the obvious benefit of “turning waste into wealth.” Challenges remain to preserve the biological structure through the harsh and laborious post‐synthetic treatments, and tailor the functionality as desired. Herein, Escherichia coli is directly coated with metal–organic frameworks (MOFs) through in situ assembly to fabricate N, P co‐doped porous carbon capsules expressing self‐phosphorized metal phosphides. While the MOF coating serves as an armoring layer for facilitating the morphology inheritance from the bio‐templates and provides metal sources for generating extra porosity and electrochemically active sites, the P‐rich phospholipids and N‐rich proteins from the plasma membrane enable carbon matrix doping and further yield metal phosphides. These unique structural and compositional features endow the carbon capsules with great capabilities in suppressing polysulfide shuttling and catalyzing reversible oxygen conversion, ultimately leading to the superb performance of lithium–sulfur batteries and zinc–air batteries. Combining the bio‐templating strategy with hierarchical MOF assembly, this work opens a new avenue for the fabrication of highly porous and functional carbon for advanced energy applications.     

Bending‐Tolerant Anodes for Lithium‐Metal Batteries

Bendable energy‐storage systems with high energy density are demanded for conformal electronics. Lithium‐metal batteries including lithium–sulfur and lithium–oxygen cells have much higher theoretical energy density than lithium‐ion batteries. Reckoned as the ideal anode, however, Li has many challenges when directly used, especially its tendency to form dendrite. Under bending conditions, the Li‐dendrite growth can be further aggravated due to bending‐induced local plastic deformation and Li‐filaments pulverization. Here, the Li‐metal anodes are made bending tolerant by integrating Li into bendable scaffolds such as reduced graphene oxide (r‐GO) films. In the composites, the bending stress is largely dissipated by the scaffolds. The scaffolds have increased available surface for homogeneous Li plating and minimize volume fluctuation of Li electrodes during cycling. Significantly improved cycling performance under bending conditions is achieved. With the bending‐tolerant r‐GO/Li‐metal anode, bendable lithium–sulfur and lithium–oxygen batteries with long cycling stability are realized. A bendable integrated solar cell–battery system charged by light with stable output and a series connected bendable battery pack with higher voltage is also demonstrated. It is anticipated that this bending‐tolerant anode can be combined with further electrolytes and cathodes to develop new bendable energy systems.     

An Oxygen‐Vacancy‐Rich Semiconductor‐Supported Bifunctional Catalyst for Efficient and Stable Zinc–Air Batteries

The highly oxidative operating conditions of rechargeable zinc–air batteries causes significant carbon‐support corrosion of bifunctional oxygen electrocatalysts. Here, a new strategy for the catalyst support design focusing on oxygen vacancy (OV)‐rich, low‐bandgap semiconductor is proposed. The OVs promote the electrical conductivity of the oxide support, and at the same time offer a strong metal–support interaction (SMSI), which enables the catalysts to have small metal size, high catalytic activity, and high stability. The strategy is demonstrated by successfully synthesizing ultrafine Co‐metal‐decorated 3D ordered macroporous titanium oxynitride (3DOM‐Co@TiO_xN_y). The 3DOM‐Co@TiO_xN_y catalyst exhibits comparable activities for oxygen reduction and evolution reactions, but much higher cycling stability than noble metals in alkaline conditions. The zinc–air battery using this catalyst delivers an excellent stability with less than 1% energy efficiency loss over 900 charge–discharge cycles at 20 mA cm^?2. The high stability is attributed to the strong SMSI between Co and 3DOM‐TiO_xN_y which is verified by density functional theory calculations. This work sheds light on using OV‐rich semiconductors as a promising support to design efficient and durable nonprecious electrocatalysts.     

Applications of Metal–Organic‐Framework‐Derived Carbon Materials

Carbon materials derived from metal–organic frameworks (MOFs) have attracted much attention in the field of scientific research in recent years because of their advantages of excellent electron conductivity, high porosity, and diverse applications. Tremendous efforts are devoted to improving their chemical and physical properties, including optimizing the morphology and structure of the carbon materials, compositing them with other materials, and so on. Here, many kinds of carbon materials derived from metal–organic frameworks are introduced with a particular focus on their promising applications in batteries (lithium‐ion batteries, lithium–sulfur batteries, and sodium‐ion batteries), supercapacitors (metal oxide/carbon and metal sulfide/carbon), electrocatalytic reactions (oxygen reduction reaction, oxygen evolution reaction, and hydrogen evolution reaction), water treatment (MOF‐derived carbon and other techniques), and other possible fields. To close, some existing problem and corresponding possible solutions are proposed based on academic knowledge from the reported literature, along with a great deal of experimental experience.