Cuticular Hydrocarbon Phenotypes Do not Indicate Cryptic Species in Fungus-Growing Termites (Isoptera: Macrotermitinae)

In several termite species, distinct differences in the composition of cuticular hydrocarbons among colonies correspond to high genetic divergence of mitochondrial DNA sequences. These observations suggest that hydrocarbon phenotypes represent cryptic species. Different cuticular hydrocarbon phenotypes also are found among colonies of fungus-growing termites of the genus Macrotermes. To determine if these hydrocarbon differences in Macrotermes also indicate cryptic species, we sequenced the mitochondrial CO I gene from species in West and East Africa. Among individuals of a supposed species but belonging to different cuticular hydrocarbon phenotypes, the genetic distances are much smaller than distances between species. Unlike what has been observed in other termites, Macrotermes hydrocarbon phenotypes do not represent cryptic species. Our findings suggest fundamental differences in the evolution and/or function of cuticular hydrocarbons among different termite lineages. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Humidity-Regulating Trays: Moisture Absorption Kinetics and Applications for Fresh Produce Packaging

For packaged fresh produce, inappropriate high relative humidity (RH) levels and condensation of water vapour cause premature spoilage. Humidity-regulating trays were developed to solve this issue. They were made from a thermoformed multilayer structure: polyethylene (outside)/foamed hygroscopic ionomer (active layer) with 0 or 12 wt% NaCl/hygroscopic ionomer (sealing layer, inside). Moisture absorption kinetics of the humidity-regulating trays with 0 and 12 wt% NaCl (T-0 and T-12, respectively) was investigated under different RH conditions (76, 86, 96 and 100 %) at 13 °C for 16 days. Additional trays containing 7 g of distilled water were closed with a high barrier lidding film, and the headspace RH was continuously monitored as a function of time. As control, a polypropylene (control-PP) tray was used. Strawberries and tomatoes were used to test capability of the trays to regulate in-package RH. The amount of water absorbed by the T-0 and T-12 trays was 7.6 and 13.2 g, respectively. Active hygroscopic ionomer layer was effective in water vapour absorption, and the integration of NaCl into this active layer increased the water vapour absorption capacity of the tray. The Weibull model adequately described the moisture sorption kinetics of the individual packaging trays as a function of time. The headspace RH of trays covered with a lidding film was found to be 89.8, 99.6 and 100 % in the T-12, T-0 and control-PP trays, respectively. The T-12 trays containing fresh produce best regulated the in-package RH below 97 % and maintained overall quality, but at the expense of slightly higher product weight loss (2–3 wt% for strawberry, 1 wt% for tomatoes) compared to the control-PP trays (0.3–0.6 wt%).     

Filtration performance at high temperatures and analysis of ceramic filter elements during biomass gasification

During the CHRISGAS project, various experimental campaigns were performed with the aim to study the hot gas filtration process during steam-O₂ biomass gasification at Delft University of Technology. The test-rig consists of a 100 kW thermal atmospheric circulating fluidized-bed gasifier and a high temperature filter unit which contains 3 rigid ceramic candles with an outer diameter of 60 mm, 10 mm wall thickness and a length of 1520 mm. This paper gives an overview of tests performed with different fuels (A-wood, B-wood, miscanthus) and with sand and magnesite used as bed materials. Dia-Schumalith¹ candles were operated in the temperature range between 600 °C and 800 °C for more than 50 h. The filtration performance was studied through continuous observation of the increasing differential pressure while the filter cake formed on the surface of the candles. Gas face velocities ranged between 3 cm s^?1 and 5 cm s^?1. Stable filtration was achieved during some tests. Dust cake analysis indicated formation of calcium phosphates and silicates and potassium silicates.     

A model of the passivation of ultrathin SiO2 layer/Si substrate interfaces by atomic hydrogen from a thermalised plasma source

A theoretical model is developed to account for the kinetics of the decrease of the density of recombination active centres at the interface of SiO₂ layers with Si(111) substrates as a result of treatment by thermalised hydrogen plasma. The recombination active centres at the SiO₂/Si interface are ascribed to be the P_b centres. The model developed takes into account the kinetics of the incorporation of hydrogen atoms into the SiO₂ layer from the plasma source and their interaction with both passivated and unpassivated P_b centres. A special attention is given to ultrathin (∼2 nm) SiO₂ layers. A simplification of the general model to this important case allows one to obtain analytical solution for the density of unpassivated recombination active P_b centres as a function of the flow of hydrogen atoms from plasma, the initial density of P_b centres, and the treatment time. The model applicability is verified comparing the results of calculations with the experimentally measured values of the relative density of recombination active centres at the ultrathin SiO₂/Si(111) substrate interface upon passivation by atomic hydrogen from thermalised plasma source. A conformity of the model predictions to the experimental results is demonstrated.     

ZF6速自动变速器的技术改进-高燃油经济性和快速动态换档

在2001年,ZF率先将6速自动变速器成功推向市场。同时,5速自动变速器已经开始被新一代6速自动变速器所取代[1,2,3,4,5]。从2001年到2003年期间,3款不同转矩的变速器开始批量生产;这些变速器可适应750Nm转矩的发动机,用于标准传动、带分动器的全轮驱动以及带一体化全轮驱动装置的前置纵向传动。到2005年末,ZF公司6速自动变速器的生产份额占总产量的90%以上。自动变速器需求不断上升导致这些变速器在技术方面的改进,明显增强了决定性的、与使用者相关的参数。其中包括:.提高功率质量比;.进一步降低油耗;.改善换档动态特性。     

Instandsetzung von Rissen in Stahlbetonbauteilen nach einer außergewöhnlichen Einwirkung

Repair of Cracks in Reinforced Concrete Structures after Accidental Action Accidental loads – for example an earthquake, a vehicle impact or blast and shock waves due to detonations – lead to local damages in RC‐structures. Both the damage assessment as well as the repair of damaged reinforced concrete are important topics with respect to a durable use of infrastructure. After damage assessment a further step focuses on the repair of damaged structural concrete. Therefore fundamental investigations concerning the use of different repair methodologies have been carried out with respect to damage after accidental action. The grouting techniques used focus on the repair of cracks, the concretes microstructure and the weakened bond between reinforcement bars and concrete in the surrounding damage zone. Furthermore this contribution includes applicationoriented experimental investigations concerning the repair of reinforced concrete components by grouting and a discussion of the appropriateness for repairing RC‐structures damaged by accidental action.     

Fiber Bragg Gratings in Small-Core Ge-Doped Photonic Crystal Fibers

This paper reports fiber Bragg gratings （FBGs） inscribed in a small-core Ge-doped photonic crystal fibers with a UV laser and a Talbot interferometer. The responses of such FBGs to temper- ature, strain, bending, and transverse-loading were systematically investigated. The Bragg wavelength of the FBGs shifts toward longer wavelengths with increasing temperature, tensile strain, and transverse-loading. The bending and transverse- loading properties of the FBGs are sensitive to the fiber orientations.     

Synthesis and Characterization of Glycidyl Azide‐r‐(3,3‐bis(azidomethyl)oxetane) Copolymers

Glycidyl azide‐r‐(3,3‐bis(azidomethyl)oxetane) copolymers were synthesized by cationic copolymerization of epichlorohydrin and 3,3‐bis(bromomethyl)oxetane, using butane‐1,4‐diol as an initiator and boron trifluoride etherate as a catalyst, followed by azidation of the halogenated copolymer. The main objective of this work is the preparation of an OH‐terminated amorphous polymer with energetic content higher than that of the well‐known glycidyl azide homopolymer. The effect of experimental conditions, i.e., the rate of monomer feeding, on the final molecular weight and functionality of the copolymer has also been investigated. The obtained copolymers were extensively characterized to determine their composition and thermal stability. The heat of reaction for the polymerization of the halogenated key precursors has also been measured. It was found that even though both the operating conditions and the catalytic system were chosen in order to favor a living character of the polymerization, the final product seems to be the result of a combined living and active chain end mechanism. In particular, the latter is responsible for the formation of oligomers and not hydroxyl‐terminated chains. Nevertheless, the average number of OH groups is high enough to allow a cross‐linking of the polymeric chains, by addition of polyisocyanates and subsequent formation of inter‐chain urethanic bonds.     

A W7-X experiment program editor––A usage driven development

The set-up of experiment programs for the complex fusion device Wendelstein 7-X has to define a multitude of parameters which have to obey large number of rules arising from physics and technical constraints. Since this is hard to automate as long as the dependencies are not known sufficiently, the W7-X CoDaC team decided to implement an editor following a constructive approach: starting from an established experiment program the user is able to modify parts of it – thus complying the usual workflow of experimenters.Already the very first implementation has been deployed at the W7-X CoDaC prototype, the WEGA stellarator. Driven by agile programming principles the weighting of the requirements has been influenced by the editor usage in the daily experiment routine, thus ensuring client-oriented development steps and short release cycles. At present, a stable program editor implementation with graphical preview, immediate feedback on user actions and instantaneous warnings about incorrect settings is under continuous operation at the CoDaC prototype. It has potential to improve together with growing knowledge about the physical and technical constraints. The experiences gained give certainty that the editor is suitable for future use during the start-up phase and the first years of W7-X operation.