In Vivo Examination of an Injectable Hydrogel System Crosslinked by Peptide–Oligosaccharide Interaction in Immunocompetent Nude Mice

Hydrogels can serve as matrices to mimic natural tissue function and be used for wide‐ranging applications such as tissue regeneration and drug delivery. Injectable hydrogels are particularly favorable because their uses are minimally invasive. However, creating moldable substance for injection often results in compromised function and stability. This study reports an injectable hydrogel system crosslinked by peptide–oligosaccharide noncovalent interaction. The dynamic network shows fast self‐healing, a property essential for injectability. Injected hydrogels in immunocompetent mice and release of encapsulated compound are monitored up to 9 months by magnetic resonance imaging (MRI) and optical imaging. This surprisingly stable hydrogel does not cause adverse inflammatory response, as analyzed by measuring cytokine levels, immunohistochemistry, and MRI. Hydrogel degradation is associated with invasion of macrophages and vascular formation. The facile synthesis, high biocompatibility, and stability of this injectable hydrogel can lead to various experimental and clinical applications in regenerative medicine and drug delivery.     

Probabilistic and technology-specific modeling of emissions from municipal solid-waste incineration

The European legislation increasingly directs waste streams which cannot be recycled toward thermal treatment. Models are therefore needed that help to quantify emissions of waste incineration and thus reveal potential risks and mitigation needs. This study presents a probabilistic model which computes emissions as a function of waste composition and technological layout of grate incineration plants and their pollution-control equipment. In contrast to previous waste-incineration models, this tool is based on a broader empirical database and allows uncertainties in emission loads to be quantified. Comparison to monitoring data of 83 actual European plants showed no significant difference between modeled emissions and measured data. An inventory of all European grate incineration plants including technical characteristics and plant capacities was established, and waste material mixtures were determined for different European countries, including generic elemental waste-material compositions. The model thus allows for calculation of country-specific and material-dependent emission factors and enables identification and tracking of emission sources. It thereby helps to develop strategies to decrease plant emissions by reducing or redirecting problematic waste fractions to other treatment options or adapting the technological equipment of waste incinerators.     

Phases and evolution of microstructures in Ti–60 at.% Al

The formation and stability of Al-rich Ti–Al phases is reviewed and the kinetics of the phase transformations and evolution of lamellar TiAl + r-TiAl₂ microstructures is discussed. For this a couple of Ti–60 at.% Al alloys were processed by different techniques to generate different initial microstructures. The kinetics were studied by annealing the differently processed alloys for 1, 10, 100 and 1000 h at temperatures between 800 and 1000 °C and then analysing the quenched microstructures by optical, scanning electron, and transmission electron microscopy. In addition, in situ heating and cooling experiments using differential thermal analysis and transmission electron microscopy were performed to verify the results obtained for the quenched samples. The results conclusively show why the metastable phases h-TiAl₂ and Ti₃Al₅ form. The stability and transformation of the metastable phases have been determined in dependence on time and temperature and the kinetics of the two different mechanisms by which the stable phase r-TiAl₂ forms have been established. The effects of differing initial microstructures on the evolution of the microstructure with time and temperature are discussed.     

NUMERICAL SIMULATION OF ALLOY SOLIDIFICATION BY A TWO－PHASE MODEL

本文介绍了合金凝固传输过程中的二相流数学模型．该模型描述了固－液界面的传输现象和液相对流对宏观偏析的影响，并考虑了生核过程，热和溶质的过冷效应，及固相颗粒的宏观运动，从而把宏观传输过程和微观结构结合起来．采用该模型，对Ａｌ－４％Ｃｕ等轴晶合金的凝固进行了完整的数值模拟．     

Predicting the occurrence and effects of defects in castings

Casting designs are generally based on strength of materials calculations and the experience of the designer. This process leads to incremental development of designs utilizing factors of safety, which lead to increased component weights and inefficient use of materials. In castings, unquantifiable factors (such as shrinkage, porosity, hot tears, and inclusions) lead to conservative design rules. Non-destructive testing does not give the designer a way to assess the effect of indications on part performance. This article describes recent work to predict the occurrence and nature of defects in castings and determine their effect on performance. For more information, contact Christoph Beckermann, University of Iowa, Department of Mechanical and Industrial Engineering, 2412 SC, Iowa City, IA 52242-1527; (319) 335-5681; fax (319) 335-5669; e-mail becker@engineering.uiowa.edu.     

Multimerization of Peptide Mimotopes for Blocking of Factor VIII Neutralizing Antibodies

About 30 % of patients with severe hemophilia A develop neutralizing antibodies (inhibitors) to coagulation factor VIII (FVIII) upon treatment with exogenous factor preparations. Two peptides, C6 (NPVENMMDRDSQ) and H10 (QSPWQTWFTRAL), that mimic putative inhibitor epitopes (mimotopes), were previously selected by phage display screening of plasma samples from patients with inhibitors. Synthetic peptide mimotopes inhibited IgG binding to FVIII (IC₅₀: 30–50 μM ). This effect was increased by an equimolar combination of both mimotopes. Mimotopes were fused to the C‐terminal multimerization domain of the C4bp α‐chain and expressed as multimers in 293T cells. Multimerized mimotopes showed improved binding to anti‐FVIII IgG and prolonged in vitro half‐life relative to synthetic peptides. The two mimotopes were combined in heteromultimers by co‐transfection of 293T cells with respective vectors, resulting in bi‐specific molecules that almost completely blocked polyclonal antibody binding to FVIII (IC₅₀: 2–3 μM ). This strategy is capable of functionally improving synthetic peptides by multimerization and could provide a basis for novel therapeutic approaches for patients with hemophilia A and inhibitors.     

Contributions to non-identifier based adaptive control in mechatronics

Funnel-Control (FC)–an adaptive (time-varying) MIMO/SISO control strategy–is re-introduced and its applicability introductory for position control of nonlinear, coupled (rigid) robotic systems and for speed control of nonlinear two-mass flexible servo systems is shown. Additionally Error Reference Control (ERC)–a direct derivative of FC–is established. ERC is specially designed with asymmetric boundaries and auxiliary reference, ensuring that the control error evolves within a prespecified tube (a shrinked funnel region, achieving even better tracking performance).FC and hence ERC are based on the high-gain stabilizability of minimum-phase systems with relative degree one and known sign of the high-frequency gain. Although the plant only needs to be known in structure, both concepts assure prescribed transient behavior without identification and/or parameter estimation.As most industrial applications, also the considered robotic and two-mass flexible servo systems, exhibit relative degrees greater than one, FC and ERC cannot directly be applied. Therefore a special state feedback is introduced, reducing the relative degree and retaining the minimum-phase property. The additional implementation of a nominal PI-like extension guarantees good disturbance rejection and asymptotic tracking of (constant) velocity and position reference trajectories.Simulation results for a 6-DOF Manutec r3 robot underpin and compare the achievable position control performance of one overall MIMO Funnel Controller for all joints and one SISO Funnel Controller for each joint (6 controllers). For nonlinear two-mass flexible servo systems, measurement results demonstrate the achievable load speed control performance of FC and ERC in comparison to optimal LQ state feedback.     

Aufzeichnung und Übertragung von Lehrveranstaltungen

Immer mehr Hochschulen gehen dazu über, Lehrveranstaltungen aufzuzeichnen und den Studierenden oder der ?ffentlichkeit zeitgleich oder zeitversetzt zug?nglich zu machen. Der Beitrag untersucht am Beispiel der Rechtslage in Hessen die damit verbundenen Eingriffe in Grundrechte der Hochschullehrenden und Studierenden, deren Rechtfertigung durch die Aufgaben der Hochschulen, die Verpflichtungen der Hochschullehrenden, die datenschutz- und urheberrechtliche Bewertung sowie die M?glichkeiten, diese Fragen durch hochschuleigenes Recht zu regeln.     

Swelling rock behaviour in a tunnel: NATM-support vs. Q-support – A comparison

The Q-system is one of the most applied classification tool in modern tunnelling. After an exact evaluation of the parameters the rock support can be determined via the “Q-support chart”. In an already finished tunnel, mainly driven through limestone, the Q-system was tested under difficult geological conditions (shale–marl). Scope of the appraisal was a comparison of the support suggested by the “Q-support chart” with the real performed support after the NATM, regarding partly massive damages. This article is a contribution referring to the last publication on the topic “fitness of various engineering design tools” from [Palmstrom, A., Stille, H., 2007. Ground behaviour and rock engineering tools for underground excavations. Tunnelling and Underground Space Technology 22, 363–376].     

Starting long-term stratospheric observations with RAMAS at Summit, Greenland

The new microwave Radiometer for Atmospheric Measurements at Summit (RAMAS) has started operation at Summit station, Greenland (72/spl deg/N, 38/spl deg/W, 3200 m), and is now being prepared for continuous measurements. RAMAS operates in the frequency band from 265-280 GHz with an instantaneous bandwidth of currently 1 GHz. It observes the emission of thermally induced rotational transitions of a variety of stratospheric trace gases, including O/sub 3/, ClO, N/sub 2/O, HNO/sub 3/, and HCN. Tropospheric water vapor content, a major constraint on ground-based microwave radiometry, is exceptionally low at Summit station. Initial measurements and retrieved profiles are presented, demonstrating the excellent measurement conditions.