Macro‐ and Microkinetic Simulation of Diesel Oxidation Catalyst: Effect of Aging,Noble Metal Loading and Platinum Oxidation

In automotive exhaust aftertreatment simulation, both macro‐ and microkinetic models are commonly used. In this contribution both models are applied for the simulation of diesel oxidation catalysts (Pt/γ‐Al₂O₃) with different catalyst loading and degree of thermal aging. The study proves that the structure insensitive kinetics of the considered catalysts can be described with the same rate equations only by scaling the rate constants of the different reaction steps with the catalytically active Pt surface, which is accessible by CO adsorption or light‐off measurements. In addition, NO oxidation is strongly influenced by a reversible, slow transformation of Pt into Pt‐oxide.     

Post-Traumatic Caspase-3 Expression in the Adjacent Areas of Growth Plate Injury Site: A Morphological Study

The epiphyseal plate is a hyaline cartilage plate that sits between the diaphysis and the epiphysis. The objective of this study was to determine the impact of an injury in the growth plate chondrocytes through the study of histological morphology, immunohistochemistry, histomorphometry and Western Blot analyses of the caspase-3 and cleaved PARP-1, and levels of the inflammatory cytokines, Interleukin-6 (IL-6) and Tumor Necrosis Factor alpha (TNF-α), in order to acquire more information about post-injury reactions of physeal cell turnover. In our results, morphological analysis showed that in experimental bones, neo-formed bone trabeculae—resulting from bone formation repair—invaded the growth plate and reached the metaphyseal bone tissue (bone bridge), and this could result in some growth arrest. We demonstrated, by ELISA, increased expression levels of the inflammatory cytokines IL-6 and TNF-α. Immunohistochemistry, histomorphometry and Western Blot analyses of the caspase-3 and cleaved PARP-1 showed that the physeal apoptosis rate of the experimental bones was significantly higher than that of the control ones. In conclusion, we could assume that the inflammation process causes stress to chondrocytes that will die as a biological defense mechanism, and will also increase the survival of new chondrocytes for maintaining cell homeostasis. Nevertheless, the exact stimulus leading to the increased apoptosis rate, observed after injury, needs additional research to understand the possible contribution of chondrocyte apoptosis to growth disturbance.     

Differences in Monoterpene Biosynthesis and Accumulation in <Emphasis Type="Italic">Pistacia palaestina</Emphasis> Leaves and Aphid-Induced Galls

Certain insect species can induce gall formation on numerous plants species. Although the mechanism of gall development is largely unknown, it is clear that insects manipulate their hosts’ anatomy, physiology, and chemistry for their own benefit. It is well known that insect-induced galls often contain vast amounts of plant defensive compounds as compared to non-colonized tissues, but it is not clear if defensive compounds can be produced in situ in the galled tissues. To answer this question, we analyzed terpene accumulation patterns and possible independent biosynthetic potential of galls induced by the aphid Baizongia pistaciae L. on the terminal buds of Pistacia palaestina Boiss. We compared monoterpene levels and monoterpene synthase enzyme activity in galls and healthy leaves from individual trees growing in a natural setting. At all developmental stages, monoterpene content and monoterpene synthase activity were consistently (up to 10 fold on a fresh weight basis) higher in galls than in intact non-colonized leaves. A remarkable tree to tree variation in the products produced in vitro from the substrate geranyl diphosphate by soluble protein extracts derived from individual trees was observed. Furthermore, galls and leaves from the same trees displayed enhanced and often distinct biosynthetic capabilities. Our results clearly indicate that galls possess independent metabolic capacities to produce and accumulate monoterpenes as compared to leaves. Our study indicates that galling aphids manipulate the enzymatic machinery of their host plant, intensifying their own defenses against natural enemies.     

Preparation, evaluation and characterization of copper catalysts for ethanol fuelled diesel engines

Copper-based monolithic honeycomb catalysts for ethanol fuelled diesel engines have been prepared and evaluated. The washcoat consisted either of alumina or titania. Two different methods to apply the active material were used; incipient wetness impregnation and deposition precipitation. The catalysts have been evaluated in a laboratory reactor and have been characterised using SEM, XRPD, TEM, TPR, XPS, BET surface area and pore-size distribution measurements. Both the choice of washcoat material as well as the preparation method is of importance. Titania as washcoat gave a better performing catalyst than alumina in this case. Deposition precipitation gave a better catalyst than incipient wetness impregnation when alumina was used as washcoat, as well as at low temperatures for titania catalysts.     

碳化铬/Ni3Al复合堆焊层组织及摩擦磨损分析

采用光学显微镜、扫描电镜、电子探针及X射线衍射分析钨极氩弧堆焊碳化铬增强Ni3Al基复合堆焊层的组织结构,并采用销盘式干摩擦磨损试验机对堆焊层与活塞环用蠕墨铸铁材料的干摩擦磨损性能进行试验比较.结果表明,复合堆焊层内形成Ni3Al金属间化合物基体,其中弥散分布有大量细小的块状和条状碳化物硬质相Cr3C2和Cr7C3;焊接时焊丝中Cr3C2颗粒溶解析出,重新析出的碳化铬颗粒中包含Fe和Ni元素,碳化铬颗粒与Ni3Al基体形成良好的冶金结合;弥散分布的碳化铬颗粒和Ni3Al基体固溶强化的Cr元素决定了堆焊层具有较高的硬度.室温条件下,复合堆焊层具有优异的耐干摩擦磨损性能,其摩擦系数为0.23,远低于活塞环蠕墨铸铁的0.39;磨损率仅为蠕墨铸铁材料的43%.     

Biomimetic design of an ultra-compact and light-weight soft muscle glove

Wearable robotic hand devices can support people doing hand-intensive tasks by reducing the physical stress and strain on the human hand. For the safety and comfort of the user, such a device should be compatible and inconspicuous. Based on these two requirements, this paper presents a biomimetic design of a wearable robotic hand device called soft muscle glove, aiming to restore the salient features and functionalities of the human hand. Inspired by the hand musculature, the soft structure of the glove contains strings, bands and shape memory alloy (SMA) spring actuators to replicate the functionalities of tendons, pulleys and muscles in the human hand. The low-mass and small-size SMA spring actuator allows an ultra-compact and light-weight design of the glove with high dexterity. The glove weighs in total 85.03 g inclusive of the actuators and microcontroller. The performance of the muscle glove was experimentally investigated through hand function tests. The experimental results suggest that the glove can achieve functional range of motion of the human hand and can perform a wide range of grasp types defined in grasp taxonomy. Moreover, the grasping performance of the muscle glove with coupled and uncoupled flexion of the finger joints was compared. The uncoupled control shows a better matching between the grasp posture and the objects form, contributing to more efficient force transmission. This confirms the benefits of the proposed highly biomimetic design.     

Viroids and the Origin of Life

Viroids are non-coding circular RNA molecules with rod-like or branched structures. They are often ribozymes, characterized by catalytic RNA. They can perform many basic functions of life and may have played a role in evolution since the beginning of life on Earth. They can cleave, join, replicate, and undergo Darwinian evolution. Furthermore, ribozymes are the essential elements for protein synthesis of cellular organisms as parts of ribosomes. Thus, they must have preceded DNA and proteins during evolution. Here, we discuss the current evidence for viroids or viroid-like RNAs as a likely origin of life on Earth. As such, they may also be considered as models for life on other planets or moons in the solar system as well as on exoplanets.     

Standortplanung für die Herstellung CO2‐basierter Chemikalien am Beispiel der Olefinproduktion

The use of CO₂ as raw material is increasingly gaining in importance as an option for climate protection and as an alternative raw material feedstock. Both direct electrochemical syntheses and thermochemical processes are associated with a high demand for electrical energy. A contribution to climate protection is only possible in the case of low‐carbon power generation, as can be realized, e.g., by wind power or solar energy. This article presents a methodology for identifying suitable sites for the CO₂‐based production of olefins in Germany.     

Case study of upgrading potential for a small hydro power station

Schemes for upgrading hydro power are formed in many parts of the world. Small hydro power (<15 MW) constitutes a fraction of all hydro power, but upgrading can still be worthwhile. In this article, a small generating station in Sweden, with two generators, is simulated with new generators. The voltage is increased by introducing a cable wound stator, thereby the transformers can be excluded, and more efficient generators are introduced with a higher power factor. These improvements lead to an active power increase from 8.9 to 9.4 MW per generator, which means an increased total annual production by 4.2 GW h.     

Surface Restructuring of Polyurethanes and its Control by Plasma Treatment

It was shown that when polyurethanes designed for use in biopolymer applications were immersed in orienting fluids, significant increases in their non-dispersive surface energies took place. The kinetics of the surface energy response were found to be a function of the immersion medium's acid-base interaction potential. Restructuring from the as-cast state, similar to that reported for two-component polyurethane adhesives, occurs in response to thermodynamic demands and is attributable to a preferential concentration of low energy segments in the surface region. Since shifting surface energies in polyurethanes may pose problems in biological applications, an attempt was made to crosslink the surface of the polymers by the use of cold, microwave plasma discharges with Argon as the treatment gas. Plasma treatments proved to be successful, in that polyurethane surfaces so modified responded much more weakly to changes in the polarity of contact media.