Robber bees (Lestrimelitta limao) and their host chemical and visual cues in nest defense byTrigona (Tetragonisca) angustula (Apidae: Meliponinae)

The nest of the stingless bee,Trigona (Tetragonisca) angustula, is guarded by bees positioned in the nest entrance and others hovering in front of it. Hovering guard bees track returning foragers sideways along the last 10 cm in front of the nest, but intercept and incapacitate nest intruders by clinging with mandibles to wings and legs. When attacked by the cleptobiotic stingless beeLestrimelitta limao, the colony strengthens its aerial defense with hundreds of additional hoverers. To test our hypothesis that this reaction is due to interspecific chemical communication based on kairomone effects, we presented synthetic cephalic volatiles of both species at the nest entrance and counted the number of bees leaving the nest and taking up hovering positions. We conclude that guard bees recognizeL. limao by the major terpenoids of their volatile cephalic secretions, geranial, neral (=citral) and 6-methyl-5-hepten-2-one; other components may fine-tune this recognition. The effect of chemical stimuli is not significantly enhanced by combination with a dummy ofL. limao. Guard bees, we hypothesize, respond to this kairomone by secreting a species specific alarm pheromone; a major component of this pheromone, benzaldehyde, recruits additional bees to defend the nest.     

SIGNIFICANCE OF TOPOCHEMICAL FACTORS ON RATE OF REACTIONS BETWEEN SOLID SALTS *

The factors determining the rate of reactions between solids are discussed. When the solid phases are internally in equilibrium and when equilibrium also is established at the phase boundaries, the kinetics are given by the geometric dimensions of the system, the free energy decrease, and the mobility of the diffusing particles in the reaction product. These conditions are not fulfilled in most practical cases, the reactions being strongly dependent on topochemical factors. Topochemical imperfections in crystals and their influence on the reaction velocity are described, but the mechanism of reactions influenced by topochemical factors can only be found empirically. The way of approach is outlined for the case of spinel formation from zinc oxide and iron oxide.     

Bordoni relaxation in kink-chains

The Bordoni relaxation in fcc metals is generally assumed to result from thermally activated kink-pair formation in dislocation segments aligned along Peierls valleys in crystallographic close-packed directions. Objections against this interpretation have been raised by pointing out, that, at the small stresses applied in the experiments, the Paré condition is not satisfied and that the Peierls stress derived from the experiments by far exceeds the experimental values for the flow stress extrapolated to 0 K. It is shown that, when the bow-out configuration of a dislocation segment is treated as a kink-chain, and when the splitting of dislocation into partials is accounted for, both objections cannot be maintained. Under the assumption that the kink mobility is high and using analytical expressions for the kink-chain configuration and the kink-chain enthalpy under stress an expression for the bow-out rate of dislocation segments is obtained. Trivial numerical integration, under the action of a periodic applied stress, leads to a phase-lag between strain and stress and hence to energy dissipation. The dependence of this energy loss on segment lengths, temperature and internal stress is derived explicitly.     

Controlling fibroblast adhesion and proliferation by 1D Al2 O3 nanostructures

The fibrotic encapsulation, which is mainly accompanied by an excessive proliferation of fibroblasts, is an undesired phenomenon after the implantation of various medical devices. Beside the surface chemistry, the topography plays also a major role in the fibroblast–surface interaction. In the present study, one‐dimensional aluminium oxide (1D Al₂ O₃) nanostructures with different distribution densities were prepared to reveal the response of human fibroblasts to the surface topography. The cell size, the cell number and the ability to form well‐defined actin fibres and focal adhesions were significantly impaired with increasing distribution density of the 1D Al₂ O₃ nanostructures on the substratum.Inspec keywords: biomechanics, adhesion, surface chemistry, biomedical materials, cellular biophysics, surface topography, nanostructured materials, alumina, nanomedicineOther keywords: fibrotic encapsulation, medical devices, surface chemistry, human fibroblasts, surface topography, cell size, cell number, well‐defined actin fibres, focal adhesions, distribution density, fibroblast adhesion, 1D nanostructures, distribution densities, fibroblast proliferation, fibroblast‐surface interaction, one‐dimensional aluminium oxide nanostructures, Al₂ O₃      

Modelling of the coupling structure of a HTS DC SQUID amplifier

In order to estimate self- and mutual inductances of the input coil and the pick-up loop of a YBCO SQUID amplifier operating at 77 K, a simple method based on the determination of the current and flux distributions into the superconductors is presented. The cases of inductors (single loop and spiral) and induced circuits (closed and open loop) are considered. The authors stress the difference between a SQUID pick-up loop and a directly coupled magnetometer depending upon their action on the input inductance. Finally, the coupling efficiency and the ground plane effect are calculated and measured for various patterns     

Scenario and roadmap-based approach for the analysis of prospective production technology needs

Technological opportunities and threats relevant to a manufacturing company have to be identified prematurely to derive purposeful measures regarding the future use of a technology in the production environment. However, the identification of technologies is resource-intensive since companies are often unable to specify their prospective technology needs. This paper therefore presents an applicable method to support producing companies in specifying technology needs. The method consists of three steps that focus on deriving, selecting and describing relevant search fields constituting those needs. Thus, technologies covering the defined needs that may represent a technological opportunity or threat for a company can be found more effectively. The method has been applied at a German automobile manufacturer.     

Chemical Validation of DegS As a Target for the Development of Antibiotics with a Novel Mode of Action

Despite the availability of hundreds of antibiotic drugs, infectious diseases continue to remain one of the most notorious health issues. In addition, the disparity between the spread of multidrug-resistant pathogens and the development of novel classes of antibiotics exemplify an important unmet medical need that can only be addressed by identifying novel targets. Herein we demonstrate, by the development of the first in vivo active DegS inhibitors based on a pyrazolo[1,5-a]-1,3,5-triazine scaffold, that the serine protease DegS and the cell envelope stress-response pathway σE represent a target for generating antibiotics with a novel mode of action. Moreover, DegS inhibition is synergistic with well-established membrane-perturbing antibiotics, thereby opening promising avenues for rational antibiotic drug design.     

Lean management in indirect business areas: modeling,analysis, and evaluation of waste

Because of the rising complexity of indirect business areas, processes become less transparent and it is therefore more difficult to distinguish between value-adding activities and waste. As an essential requirement for purposeful optimization, all existing types of waste in a process must be identified and quantified in terms of their negative impacts on the process productivity and the customer’s wishes. Hence, this article proposes an approach that increases the transparency and ensures objectivity by concentrating on the value stream, revealing weaknesses, detecting their causes, and evaluating the impact on the process according to the philosophy of Lean Management. The methodology is separated into three main steps: process modeling, analysis, and the evaluation of waste in indirect business areas. This results in an effect-orientated classification of potential waste in the process and yields a priority list of fields of action. The basis for the implementation of process optimization is thus developed.     

Evaluation of the economic feasibility of RFID in the supply chain

The distributed value added in the automotive network enables the manufacturing of customized products at lower production costs. However the coordination of the processes requires an absolute transparency and a high coordination effort within the companies and among them. To reduce operating expenses the companies bank on a cooperative implementation of the RFID technology. Unfortunately this is associated with high investments, complex process transformations and technical issues. Furthermore the identification of the benefits is a major challenge. Based on this, it was necessary to develop a method for the evaluation of the economic feasibility of RFID in the supply chain. This method was introduced in order to prove the cost effectiveness of investments. These focused primarily on identifying and quantifying all factors influencing the economy. In addition, analytical methods were developed for the generation of a broad decision basis. An overview about the single steps of the method is described in the following article.