Double-Bond Isomerization of Rapeseed Oil Methyl Esters in a Continuous Flow Reactor Efficiently Catalyzed by H-Mordenite

Unsaturated fatty acids are attractive alternatives to fossil-based materials as a source of hydrocarbons, but potential applications are limited by the preset chain length of 16–20 carbon atoms. However, if the double bond can be randomly moved along the chain, subsequent bond-breaking operations such as ethenolysis or oxidative cleavage will give rise to products with chain lengths ranging from 2 to 18 carbon atoms. A process for the double bond isomerization of rapeseed oil methyl esters in a flow-through reactor using zeolites as the catalyst is herein disclosed. Using H-mordenite as the catalyst at a flow of 0.125 mL min⁻¹ at 290 °C, near equilibrium isomerization is reached with up to 49% recovery of linear monomeric products after 5 h and up to 44% after 48 h. The main side products are oligomers (3%–15%) and skeletal isomerization products (10%–23%). Practical applications: With a suitable follow-up modification addressing the double bond (metathesis, ozonolysis, oxidative cleavage), the product mixtures of double-bond positional isomers can be used in the production of short-chain base chemicals. In repetitive combination with metathesis catalysis, biofuels with customized chain length distributions can be generated.     

Impact of Ferroelectric Layer Thickness on Reliability of Back-End-of-Line-Compatible Hafnium Zirconium Oxide Films

Due to its ferroelectricity, hafnium oxide has attracted a lot of attention for ferroelectric memory devices. Amongst different dopant elements, zirconium is found to be beneficial due to the relatively low crystallization temperature of hafnium-zirconium-oxide (HZO), thus it is back-end-of-line (BEoL) compatible. The thickness of HZO has a significant impact on ferroelectric device reliability. High operation temperatures and high endurance are important criteria depending on the application. Herein, various HZO thicknesses (7, 8, and 10 nm) in MFM (metal-ferroelectric-metal) capacitors are investigated at varying operation temperatures (25 to 175 °C) at varying electric fields (±3 to ±5.4 MV cm⁻¹) with respect to polarization, leakage current, endurance, and retention. 7 nm HZO showed promising results with an endurance of 10⁷ cycles, with a low leakage current density, and almost no retention loss after 10 years. Extrapolated results at operation conditions (±2 MV cm⁻¹ and 10 MHz) showed an endurance of 10¹⁰ cycles.     

High‐speed atmospheric atomic layer deposition of ultra thin amorphous TiO2 blocking layers at 100 °C for inverted bulk heterojunction solar cells

Ultrafast, spatial atmospheric atomic layer deposition, which does not involve vacuum steps and is compatible with roll‐to‐roll processing, is used to grow high quality TiO₂ blocking layers for organic solar cells. Dense, uniform thin TiO₂ films are grown at temperatures as low as 100 °C in only 37 s (~20 nm/min growth rate). Incorporation of these films in P3HT‐PCBM‐based solar cells shows performances comparable with cells made using TiO₂ films deposited with much longer processing times and/or higher temperatures. Copyright © 2013 John Wiley & Sons, Ltd.     

Engineered Platelet-Derived Growth Factor-Releasing Hydrogels Promote Fetal Membrane Healing In Vivo

Fetoscopic interventions to treat fetal anomalies are currently performed for a variety of conditions. Depending on the procedure, preterm rupture of the fetal membranes (FMs) happens in around 30% of the cases, potentially leading to preterm birth and fetal morbidity and mortality. Here, the capacity of modular transglutaminase crosslinked poly(ethylene glycol) (TG-PEG) hydrogels that release platelet-derived growth factor (PDGF)-BB to promote FM healing is described. In vitro, such growth factor-loaded hydrogels are able to stimulate amniotic cell migration and proliferation. When applied in vivo, these TG-PEG hydrogels tightly seal the FM and uterus defects created by a fetoscope and remain stable for 10 days. The migration of healing-related cells into such hydrogels in the myometrium, endometrium, and FM areas is only possible in soft TG-PEG hydrogels. Importantly, bioengineered hydrogels releasing PDGF-BB promote recruitment of host cells from the myometrium and the endometrium, and to a lesser extent from FM areas. In such hydrogels, the potent proliferation and matrix production of the recruited cells at the site of treatment into the biomaterial initiates a robust early healing response. PDGF-BB-loaded TG-PEG hydrogels hold great promise for the treatment of fetoscopy-induced FM defects and for the prevention of preterm birth.     

Design of Stimuli-Responsive Peptides and Proteins

Stimuli-responsive peptides and proteins are an exciting class of smart biomaterials for various applications and have received significant attention over the past decades. A wide variety of stimuli such as temperature, pH, ions, enzymes, magnetic field, redox, etc., are explored. This article provides a review of five intensively studied types of stimuli-responsive peptides and proteins, their design principles and applications, including temperature-, pH-, light-, metal ion-, and enzyme-responsive with an emphasis on the key design concepts and switch function. Moreover, typical examples of their applications are discussed to provide a better understanding of the design concept and underlying methodology. This review will facilitate and inspire future innovation toward new peptide- and protein-based materials and their diverse applications.     

High-Resolution Patterning of Organic–Inorganic Photoresins for Tungsten and Tungsten Carbide Microstructures

Tungsten is an important material for high-temperature applications due to its high chemical and thermal stability. Its carbide, that is, tungsten carbide, is used in tool manufacturing because of its outstanding hardness and as a catalyst scaffold due to its morphology and large surface area. However, microstructuring, especially high-resolution 3D microstructuring of both materials, is a complex and challenging process which suffers from slow speeds and requires expensive specialized equipment. Traditional subtractive machining methods, for example, milling, are often not feasible because of the hardness and brittleness of the materials. Commonly, tungsten and tungsten carbide are manufactured by powder metallurgy. However, these methods are very limited in the complexity and resolution of the produced components. Herein, tungsten ion-containing organic–inorganic photoresins, which are patterned by two-photon lithography (TPL) at micrometer resolution, are introduced. The printed structures are converted to tungsten or tungsten carbide by thermal debinding and reduction of the precursor or carbothermal reduction reaction, respectively. Using TPL, complex 3D tungsten and tungsten carbide structures are prepared with a resolution down to 2 and 7 μm, respectively. This new pathway of structuring tungsten and its carbide facilitates a broad range of applications from micromachining to metamaterials and catalysis.     

Parameter Optimization of the ARBURG Plastic Freeforming Process by Means of a Design of Experiments Approach

Additive manufacturing finds more applications every day, especially in medical devices, ranging from models, tools, to implants. The fabricated parts have to withstand the mechanical loading applied during their lifetime. Hence, optimization of process parameters must be performed to reach the best performance of the manufactured part with the given polymer. A fractional design of experiments is performed with the ARBURG plastic freeforming using a medical-grade poly (methyl methacrylate) to improve the overall mechanical performance. Tensile specimens are produced, tested, and the impact of different parameter settings is analyzed to identify the factors with the highest impact on the mechanical performance. Based on the results, further parameter optimization is performed. A direct correlation between the density and the tensile properties of the printed parts is observed. Further, an influence of the processing pressure resulting from changes in the processing temperature is detected. Optimization for good mechanical performance is performed, and a relation between the filling of the parts, the nozzle temperature, and the discharge pressure on to the tensile properties is found. This investigation reveals that shrinkage due to changes in temperature and pressure has an essential role in determining the tensile properties of specimens produced by ARBURG plastic freeforming.     

Biomimetic S-Adenosylmethionine Regeneration Starting from Multiple Byproducts Enables Biocatalytic Alkylation with Radical SAM Enzymes**

S-Adenosylmethionine (SAM) is an enzyme cofactor involved in methylation, aminopropyl transfer, and radical reactions. This versatility renders SAM-dependent enzymes of great interest in biocatalysis. The usage of SAM analogues adds to this diversity. However, high cost and instability of the cofactor impedes the investigation and usage of these enzymes. While SAM regeneration protocols from the methyltransferase (MT) byproduct S-adenosylhomocysteine are available, aminopropyl transferases and radical SAM enzymes are not covered. Here, we report a set of efficient one-pot systems to supply or regenerate SAM and SAM analogues for all three enzyme classes. The systems’ flexibility is showcased by the transfer of an ethyl group with a cobalamin-dependent radical SAM MT using S-adenosylethionine as a cofactor. This shows the potential of SAM (analogue) supply and regeneration for the application of diverse chemistry, as well as for mechanistic studies using cofactor analogues.