Serendipitous Identification of a Covalent Activator of Liver Pyruvate Kinase

Enzymes are effective biological catalysts that accelerate almost all metabolic reactions in living organisms. Synthetic modulators of enzymes are useful tools for the study of enzymatic reactions and can provide starting points for the design of new drugs. Here, we report on the discovery of a class of biologically active compounds that covalently modifies lysine residues in human liver pyruvate kinase (PKL), leading to allosteric activation of the enzyme (EC₅₀=0.29 μM). Surprisingly, the allosteric activation control point resides on the lysine residue K282 present in the catalytic site of PKL. These findings were confirmed by structural data, MS/MS experiments, and molecular modelling studies. Altogether, our study provides a molecular basis for the activation mechanism and establishes a framework for further development of human liver pyruvate kinase covalent activators.     

Interaction of titanium diboride/boron nitride evaporation boats with aluminium

Hexagonal boron nitride/titanium diboride composites are widely used as evaporation boats for aluminium deposition to produce functional and decorative layers on different target materials. The lifetime of such a material is limited mainly by the interaction of the metal with the ceramic substrate, but the corrosion mechanism has still not yet been thoroughly investigated and understood. In this article the corrosion mechanism for the evaporation boats used was investigated using thermodynamic calculations, FESEM, EDX and XRD phase analysis. The analysis showed that hexagonal boron nitride (hBN), which is thermodynamically less stable than TiB₂, is passivated during the application process through the formation of AlN surface layers, whereas the thermodynamically more stable TiB₂ phase dissolves and Ti-rich components precipitate in cooler regions of the evaporation boats.     

Near-zero triangular location through time-slotted mobility prediction

To setup efficient wireless mesh networks, it is fundamental to limit the overhead needed to localize a mobile user. A promising approach is to rely on a rendezvous-based location system where the current location of a mobile node is stored at specific nodes called locators. Nevertheless, such a solution has a drawback, which happens when the locator is far from the source–destination shortest path. This results in a triangular location problem and consequently in increased overhead of signaling messages. One solution to prevent this problem would be to place the locator as close as possible to the mobile node. This requires however to predict the mobile node’s location at all times. To obtain such information, we define a mobility prediction model (an agenda) that, for each node, specifies the mesh router that is likely to be the closest to the mobile node at specific time periods. The location service that we propose formalizes the integration of the agenda with the management of location servers in a coherent and self-organized fashion. To evaluate the performance of our system compared to traditional approaches, we use two real-life mobility datasets of Wi-Fi devices in the Dartmouth campus and Taxicabs in the bay area of San Francisco. We show that our strategy significantly outperforms traditional solutions; we obtain gains ranging from 39 to 72% compared to the centralized scheme and more than 35% compared to a traditional rendezvous-based solution.     

Kinetics of rare earth incorporation and its role in densification and microstructure formation of α-Sialon

The reproducible sintering and microstructure formation of α- and α/β-Sialons is a precondition for the production of such materials with reproducible properties.The Rietveld method was used for quantitative analysis of the phase composition and the kinetics of incorporation of the rare earth into the α-Sialon structure. The analysis showed that in the early stages of sintering more rare earth cations were incorporated into the grains than would be expected from the equilibrium conditions. This was observed for all investigated rare earths (Y, Nd and Yb) with different ionic radii. The consequences for sintering and microstructure formation are the fast disappearing of the transient liquid and the formation of polytypes. The use of excess of rare earth in comparison to the stoichiometric Sialon composition results in a stable residual liquid. It allows reproducible densification, anisotropic grain growth and materials with high fracture toughness.     

Effects of the amount of fillers and of the crosslink density on the mechanical behavior of carbon‐black filled styrene butadiene rubbers

Several carbon‐black filled styrene‐butadiene rubbers are subjected to monotonic uniaxial tension tests in order to investigate the effects of the amount of fillers and of the crosslink density on their mechanical properties. The Young modulus, the volume changes associated with material damage and the stretch to failure are extracted and discussed. Results compare well to the literature results when exist and quantitative analysis are proposed when possible. Results show that filled rubbers are not incompressible when submitted to uniaxial tension tests and their volume changes are strongly dependent of the amount of fillers but are unaffected by the crosslink density. The latter shows strong impact on the filled rubbers stretch to failure but more interestingly this impact is comparable to what is encountered in unfilled rubbers. The stretch to failure is improved by the addition of fillers with an optimum for material filled around 30 phr. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Verhalten von Mauerwerksbauten unter Erdbebeneinwirkung: Auswertung der Schäden des Albstadt‐Erdbebens vom 3. September 1978

Numerische Untersuchungen zum Verhalten von Mauerwerksbauten unter Erdbebeneinwirkung führen oft zu pessimistischen Schadensprognosen, welche im Gegensatz zu den Beobachtungen stehen. Um diesen Widerspruch aufzulösen, werden erfahrungsbasierte Verletzbarkeitsfunktionen für typische Mauerwerksgebäude auf der Grundlage der durch das Erdbeben vom 3. September 1978 bei Albstadt (mit einer Lokalmagnitude M_L von 5,7 und Epizentralintensität I₀ = VII—VIII) verursachten Schäden entwickelt. Anhand des Bauwerksbestandes von 1978 erfolgt die Einordnung der beobachteten Schäden in Schadensgrade auf Basis der European Macroseismic Scale EMS‐98 [1]. Die für den Bauwerksbestand repräsentativen Bauweisen werden herausgearbeitet; für die vorherrschenden Gebäude aus unbewehrtem Mauerwerk ist eine weitere Unterscheidung nach Baualter, Geschosszahl und phänomenologischen Gesichtspunkten möglich. Vulnerability of masonry structures under seismic action: Damage analysis of the September 3, 1978 Albstadt earthquake. Numerical studies of the earthquake behavior of masonry buildings in Central Europe based on national building codes acc. to the Eurocode 8 lead to pessimistic damage prognoses, which are in contradiction to the observed behavior. In order to eliminate this discrepancy realistic experience‐based vulnerability and displacement functions for typical masonry constructions are developed. Because of the rather limited number of earthquake damage observations, the Magnitude M_L 5.7 Albstadt earthquake from September 3, 1978 (intensity VII—VIII) in South Germany also based on its excellent documentation is reconstructed with the building stock existing at that time. The prevailing building types and for these the characteristic damage cases are investigated in close cooperation with the local authorities. The presented unreinforced masonry structures are divided by year of construction, number of storeys and phenomenological aspects.     

Reconfigurable handling system

The demand for more versatile assembly and handling systems to facilitate customized production is gaining in importance, especially with regard to the constantly-increasing cost pressure, to expansion of the range of product versions and the shortening of innovation cycles. As a cost-effective approach for frequently changing assembly tasks, a novel manipulation concept has been developed by combining given robot technologies. This new handling system has a modular and adaptable layout, which consists of several mobile arms to manipulate the object in six-dimensional Cartesian space. After grasping, when the arms are attached to the object, the mechanical architecture is similar to parallel manipulators or cooperating robots. As the mounting and gripping points of the arms can easily be changed, the manipulator can be reconfigured so as to match the user’s preferences and needs. In addition to the kinematic adaption the regarding task, the hardware and new functions can be reconfigured as well. Contact elements, measurement and assembly devices as well as testing modules can easily be in integrated in the concept. A modular automatic control concept combined with a self-optimizing planning tool helps the user to find the optimal configuration and realize it in an economic way.     

New wood-polymer composites containing ethyl α-hydroxymethyl acrylate polymers

Ethyl α-hydroxymethyl acrylate (EHMA) was synthesized and evaluated as a candidate for wood impregnation and in-situ polymerization. Southern Pine softwood was impregnated under a variety of conditions with EHMA alone and with various comonomers plus free radical initiator. Following thermal polymerization, the wood-polymer composites were tested for increased dimensional stability (water soaking swell resistance) and mechanical properties over untreated wood. The greatest increase in dimensional stability was attained using EHMA alone, while the maximum compression modulus was achieved by impregnating with 1:1 EHMA-styrene and styrene alone. The composites were further characterized by ¹³C CP/MAS solid state NMR and scanning electron microscopy.