Off-Pathway-Sensitive Protein-Splicing Screening Based on a Toxin/Antitoxin System

Protein-splicing domains are frequently used engineering tools that find application in the in vivo and in vitro ligation of protein domains. Directed evolution is among the most promising technologies used to advance this technology. However, the available screening systems for protein-splicing activity are associated with bottlenecks such as the selection of pseudo-positive clones arising from off-pathway reaction products or fragment complementation. Herein, we report a stringent screening method for protein-splicing activity in cis and trans, that exclusively selects productively splicing domains. By fusing splicing domains to an intrinsically disordered region of the antidote from the Escherichia coli CcdA/CcdB type II toxin/antitoxin system, we linked protein splicing to cell survival. The screen allows selecting novel cis- and trans-splicing inteins catalyzing productive highly efficient protein splicing, for example, from directed-evolution approaches or the natural intein sequence space.     

Low‐Temperature Chemical Synthesis of High‐Purity Diacylglycerols (DAG) from Monoacylglycerols (MAG)

A chemical method was developed for low‐temperature synthesis of DAG from MAG followed by an easy purification procedure in order to obtain high‐purity DAG. Solvent‐assisted and solvent‐free reaction conditions were used, combined with different catalysts (sodium methoxide, p‐toluenesulfonic acid, methanesulfonic acid, and sulfuric acid). All reactions were performed at 35 and 70 °C. By increasing both acidity and polarity of the catalyst the equilibrium shifts towards the formation of DAG. When using sulfuric acid in solvent‐assisted condition at 70 °C, 88 % conversion was obtained after 20 min of reaction (77 % w/w DAG in the reaction mixture after evaporation of the solvent). After purifying by means of column chromatography, 96 % pure DAG were obtained. The overall yield of DAG was 81 %.     

Evaluation of non-linear strain paths using Generalized Forming Limit Concept and a modification of the Time Dependent Evaluation Method

The prediction of formability is one of the most important tasks in sheet metal forming process simulation. The common criterion for ductile fracture in industrial applications is the Forming Limit Diagram (FLD). This is only applicable for linear strain paths. However, in most industrial simulation cases non-linear strain paths occur. To resolve this problem, a phenomenological approach is introduced, the so-called Generalized Forming Limit Concept (GFLC). The GFLC enables prediction of localized necking on arbitrary non-linear strain paths. Another possibility is the use of the Time Dependent Evaluation Method (TDEM) within the simulation as a failure criteria. During the Numisheet Benchmark 1 (2014) a two-stage forming process was performed with three typical sheet materials (AA5182, DP600 and TRIP 780) and three different blank shapes. The task was to determinate the point in time and space of local instability. Therefore the strain path for the point of maximum local thinning is evaluated. To predict the start of local necking the Generalized Forming Limit Concept (GFLC), the Time Dependent Evaluation Method (TDEM) and the modified TDEM were applied. The results of the simulation are compared with the results of the Benchmark experiment.     

Experiments and Simulations on the Cleaning of a Swellable Soil in Plane Channel Flow

ABSTRACT

The cleaning behavior of a soil with physical properties that depend on the wetting time is studied experimentally via the local phosphorescence detection method and simulated numerically in fully developed plane channel flow for Reynolds numbers up to 30,000. A computationally inexpensive general cleaning model is proposed, adopting an existing removal model and coupling it to the turbulent flow field. The influence of the soil on the flow is neglected and the transient behavior of the soil during cleaning is modeled in the form of a transient Dirichlet boundary condition. This approach is innovative for computational fluid dynamics of this phenomenon. The way of determining the model parameters from the experiment is described. The comparison of the simulation results with experimental data reveals very good suitability of the model in the case of a starch soil. A similar good agreement is found for data for a model protein foulant in tube flow from the literature.     

Graphoepitaxy of High‐Quality GaN Layers on Graphene/6H–SiC

The implementation of graphene layers in gallium nitride (GaN) heterostructure growth can solve self‐heating problems in nitride‐based high‐power electronic and light‐emitting optoelectronic devices. In the present study, high‐quality GaN layers are grown on patterned graphene layers and 6H–SiC by metalorganic chemical vapor deposition. A periodic pattern of graphene layers is fabricated on 6H–SiC by using polymethyl methacrylate deposition and electron beam lithography, followed by etching using an Ar/O₂ gas atmosphere. Prior to GaN growth, an AlN buffer layer and an Al_0.2Ga_0.8N transition layer are deposited. The atomic structures of the interfaces between the 6H–SiC and graphene, as well as between the graphene and AlN, are studied using scanning transmission electron microscopy. Phase separation of the Al_0.2Ga_0.8N transition layer into an AlN and GaN superlattice is observed. Above the continuous graphene layers, polycrystalline defective GaN is rapidly overgrown by better quality single‐crystalline GaN from the etched regions. The lateral overgrowth of GaN results in the presence of a low density of dislocations (≈10⁹ cm⁻²) and inversion domains and the formation of a smooth GaN surface.     

Release of Cu2+ from a copper-filled TiO2 coating in a rabbit model for total knee arthroplasty

The aim of this study was the investigation of a copper-filled TiO₂ coating, that in vitro showed good antibacterial properties combined with good tissue tolerance in an animal model. To better understand the antibacterial mechanism of the bioactive coating the release of copper (Cu) ions over time was monitored to be able to detect possible threats as well as possible fields of application. 30 New Zealand White rabbits were divided into two groups with 15 animals per group. In group 1 (control group) Ti6Al4 V bolts were implanted into the distal femur, in group 2 the Ti6Al4 V bolts were coated with four TiO₂-coatings with integrated Cu²⁺-ions (4 × Cu–TiO₂). Blood tests were performed weekly until the animals were sacrificed 4 weeks postoperative. The maximum peak of Cu and ceruloplasmin concentration could be seen in both groups one week postoperative, whereas the Cu values in group II were significantly higher. The Cu concentration in both groups approximated the initial basic values 4 weeks postoperative. The 4 × Cu–TiO₂ coating tested in our rabbit model for total knee arthroplasty is an active coating that releases potentially antibacterial Cu²⁺ for 4 weeks with a peak 1 week postoperative. The bioactive coating could be a promising approach for a use in the field of implant related infection, orthopaedic revision and tumor surgery in the future.     

Fast and exact synthesis of stationary multivariate Gaussian time series using circulant embedding

A fast and exact procedure for the numerical synthesis of stationary multivariate Gaussian time series with a priori prescribed and well controlled auto- and cross-covariance functions is proposed. It is based on extending the circulant embedding technique to the multivariate case and can be viewed as a modification and variation around the Chan and Wood algorithm proposed earlier to solve the same problem. The procedure is shown to yield time series possessing exactly the desired covariance structure, when sufficient conditions are satisfied. Such conditions are discussed theoretically and examined on several examples of multivariate time series models. Issues related to prescribing a priori the spectral structure rather than the covariance one are also discussed. Matlab routines implementing this procedure are publicly available at http://www.hermir.org.     

Chronologie des EHEC O104:H4 Ausbruchsgeschehens bis zur Gr��ndung der l?nder��bergreifenden Task Force EHEC aus Sicht der Lebensmittel��berwachung in Schleswig-Holstein am Beispiel des Kreises Schleswig-Flensburg

The article describes the chronology of events of the recent EHEC O104:H4 outbreak from the perspective of food inspection in Schleswig-Holstein until the National Task Force EHEC was founded. Taking the district of Schleswig-Flensburg as an example, the collaboration and information exchange between health and food control authorities is described. The Ministry of Agriculture, Environment and Rural Areas of Schleswig-Holstein (MLUR) received the first information about clusters of disorders with symptoms of bloody diarrhoea and HUS from the districts around Hamburg and the city of Hamburg on 19 May 2011. On the same day, the veterinary services and the service for consumer protection in the district of Schleswig-Flensburg were informed about a situation comparable to the one in the environment of Hamburg. Due to this situation, official procedures were initiated to discover the origins of this food-associated outbreak - both at the state and county level and in collaboration with the health authorities. On 1 June 2011, an initial telephone conference was held between the responsible ministries and the food inspection and health authorities of the counties and cities in order to coordinate a joint action. On 3 June 2011, the National Task Force EHEC was founded at the Federal Office for Consumer Protection and Food Safety (BVL) in Berlin. By founding the National Task Force EHEC, the coordination of the clearing process was passed over to the BVL two weeks after the public health authorities had knowledge of accumulated and cross-border cases. On 7 June 2011 an employee of the district Schleswig-Flensburg was sent to the Task Force EHEC in Berlin by the MLUR. The lesson to be learned as a result of the EHEC O104:H4 outbreak is that among the ??dangerous foods?? there are more plant-based foods than often assumed. In the future this must be much more taken into account.