Primary Steps of pH‐Dependent Insulin Aggregation Kinetics are Governed by Conformational Flexibility

Insulin aggregation critically depends on pH. The underlying energetic and structural determinants are, however, unknown. Here, we measure the kinetics of the primary aggregation steps of the insulin monomer in vitro and relate it to its conformational flexibility. To assess these primary steps the monomer concentration was monitored by mass spectrometry at various pH values and aggregation products were imaged by atomic force microscopy. Lowering the pH from 3 to 1.6 markedly accelerated the observed aggregation kinetics. The influence of pH on the monomer structure and dynamics in solution was studied by molecular dynamics simulations, with the protonation states of the titrable groups obtained from electrostatic calculations. Reduced flexibility was observed for low pH values, mainly in the C terminus and in the helix of the B chain; these corresponded to an estimated entropy loss of 150 J mol^?1 K^?1. The striking correlation between entropy loss and pH value is consistent with the observed kinetic traces. In analogy to the well‐known Φ value analysis, this result allows the extraction of structural information about the rate determining transition state of the primary aggregation steps. In particular, we suggest that the residues in the helix of the B chain are involved in this transition state.     

Analysis of influence of imperfections on stiffness of fully anchored light-frame timber shear walls—elastic model

In order to stabilize light-frame timber buildings against horizontal loads, the diaphragm or in-plane action of roofs, floors and walls is often used. This paper deals with the influence of imperfections such as gaps and uplift on the horizontal displacement of fully anchored shear walls. The significance of analyzing the effects of imperfections is evident when evaluating the stiffness of shear walls; tests of walls show that the horizontal displacement is underestimated in calculations using the stiffness of sheathing-to-framing joints as obtained from experiments. Also, in real structures where hold-downs are used according to the elastic design method, the influence of gaps and uplift should be included in order to obtain realistic displacements in the serviceability limit state. A new elastic model for the analysis, based on linear elastic behaviour of the mechanical sheathing-to-framing joints, is presented and the equations for the stiffness and the deflection versus the number of segments in the wall are derived. The fully anchored condition for the shear walls are modelled by applying a diagonal load to the wall. Three types of imperfections are evaluated: gaps at all studs, a gap only at the trailing stud, and gaps at all studs, except at the trailing stud. It is shown that the effect of imperfections on the stiffness of the wall in the initial stage is considerable. Depending on the distribution of the gaps and the number of segments included in the shear wall, the displacement of the shear wall is increased several times compared to that of a fully anchored shear wall with no gaps; e.g. for a single segment wall more than three times. However, for walls with more than six to ten segments, the effect of imperfections can be neglected. Finally, the theoretical model is experimentally verified.     

From Single Grains to Texture

Structural materials, such as metals, ceramics, and their composites are most often polycrystalline. The nature, morphology, and composition of their microstructure determine in large measure the mechanical properties of the final product, and the art to design novel materials is to find particular arrangements which make them harder, more shock absorbing, heat resistant, or self‐recovering upon damage and aging. The understanding of the basic processes and their interplay in a polycrystalline structure are most important for improved simulation of plastic deformation and to predict their thermo‐mechanical behavior.     

Silver Nanoparticles with Controlled Dispersity and Their Assembly into Superstructures

In this paper we report on the influence of particle size distribution, particle substrate interaction, and drying behavior on the self‐assembly process using ligand stabilized silver particles. Two‐dimensional particle arrays were characterized using transmission electron microscopy and extensive image analysis. The formation of such structures was observed in situ using an environmental scanning electron microscope in WET‐STEM mode. The results confirm that a small particle size distribution is crucial for the formation of regular particle patterns with long range order, but also the particle substrate interaction and the particle density have an influence on the degree of ordering. Additionally, we find that separated binary particle assemblies keep the orientation of their two‐dimensional hexagonal lattices over alternating domains of small and big particles. This is probably enabled due to the formation of dislocations and a small change of the course of the lattice lines within the respective boundary.     

Flame Sprayed Al-12Si Coatings for the Improvement of the Adhesion of Composite Casting Profiles

In this study, flame sprayed Al-12Si coatings were produced on the surface of inlays (aluminum profiles) of composite castings parts. The aim was to enhance the strength between the joining partners inlay and cast. Due to the high surface roughness and the presence of pores in the coatings, combined with the formation of an intermetallic phase at the interface, the adhesion of flame sprayed inlays could be enhanced by a factor of 2 compared to blank inlays and by a factor of 1.3 when compared to sand-blasted inlays. However, results also show that gaps are present, mostly at the interface between the inlays and the flame sprayed coatings, and these gaps have a negative effect on the joining strength of the composite casting parts. Therefore, optimizing the adhesion of the coating on the Al profiles via an improvement in both the sand-blasting and the flame spraying parameters would be beneficial for further enhancement of the adhesion of composite casting parts.     

Levels of antimony,arsenic, cadmium,copper, lead,mercury, selenium,silver, tin and zinc in bone tissue of industrially exposed workers

The contents of the elements antimony, arsenic, cadmium, copper, lead, mercury, selenium, silver, tin and zinc in bone tissue from autopsy specimens of the femur of workers who had been exposed to a large number of metals in a smeltery and refinery in Northern Sweden as well as of a control group have been quantitatively assayed.The analytical techniques used were atomic absorption spectrophotometry, neutron activation analysis and particle induced X-ray emission analysis (PIXE) in a proton microprobe. Increased levels of lead in the bone tissue of exposed workers compared to a non-exposed control group were observed. The median level of lead in the group of exposed workers exceeded the corresponding value of the control group about 5 times.Using the proton microprobe in the PIXE-mode, concentration profiles of copper, lead and zinc were examined within the Haversian system of the bone samples.     

City energy management through underground storage

This paper traces the historical development of the energy infrastructure of cities. As a result of 150 years of this infrastructure mainly comprises electricity, gas, and, sometimes, district heating. This paper describes basic characteristics of underground storage systems applicable within city limits: gas storage, compressed air energy storage, and thermal storage. Finally, the paper describes a central storage facility for all energy forms that has the potential to provide much of the flexibility required for optimal city energy management.     

Fatalities in Swedish skydiving

Exact risk patterns in skydiving fatalities are not well known, but incomplete world injury data indicate that many are preventable. A comprehensive national material for Sweden of 37 skydiving fatalities 1964–2003 were reviewed to identify risk factors. In relation to jump volume, the period 1994–2003 had a fatality rate 11 times lower than 1964–1973. Student skydivers had the highest risk of fatal outcome, often caused by instability in freefall leading to unstable parachute activation with subsequent line entanglement, or parachute activation failure. Unintentional water landings also contributed to student fatality, with life jacket malfunctions, neglect to use life jackets, and automatic reserve parachute activation devices activated by water as aggravating factors. One-third of all fatalities had an inflated and operational parachute at some point prior to injury. A drastic worldwide increase in fatal landing incidents with fast wing parachutes during the 1990s did not occur in Sweden. Every fourth fatality caused by rapid deceleration against ground or water survived impact and died during transports or in hospitals. Rescue units and health care providers can improve management of skydiving incidents from knowledge about the incident and injury mechanisms we have described, and the skydiving community can target risk factors in preventive safety work.