Two are Better than One: Combining ZnO and MgF2 Nanoparticles Reduces Streptococcus pneumoniae and Staphylococcus aureus Biofilm Formation on Cochlear Implants

Streptococcus pneumoniae (S. pneumoniae) and Staphylococcus aureus (S.aureus) are considered the most common colonizers of cochlear implants (CI), which have prompted the search for new ways to inhibit their growth and biofilm development. In the current study, CI‐based platforms are prepared and sonochemically coated with ZnO or MgF₂ nanoparticles (NPs), two agents previously shown to possess antibacterial properties. Additionally, a method is developed for coating both ZnO and MgF₂ on the same platform to achieve synergistic activity against both pathogens. Each surface is characterized, and the optimal conditions for the NP homogenous distribution on the surface are determined. The ZnO‐MgF₂ surface significantly reduces the S. pneumoniae and S. aureus biofilm compared with the surfaces coated with either ZnO or MgF₂, even though it contains smaller amounts of each NP type. Importantly, leaching assays show that the NPs remain anchored to the surface for at least 7 d. Finally, biocompatibility studies demonstrate that coating with low concentrations of ZnO‐MgF₂ results in no toxicity toward primary human fibroblasts from the auditory canal. Taken together, these findings underscore the potential of using NP combinations such as the one presented here to efficiently inhibit bacterial colonization and growth on medical devices such as CIs.     

Impedance modelling of air electrodes in alkaline media

A mathematical model of the impedance response of porous air electrodes in alkaline solutions, based on flooded agglomerate theory, was developed. The model results provides insight into characteristic features of the impedance spectra according to the relative rate of the various reactions and mass transfer processes occurring. The modelled spectra where dissolution, transport and reaction of oxygen dominates the impedance are close to ideal semicircles. With increasing contribution from ionic transport in the solution inside the pores, two distinct features occur, namely the appearance of a 45° branch at high frequencies, and an inductive loop at low frequenices. Examples from the literature where inductive loops occurs are given.     

Mutasynthesis-derived myxalamids and origin of the isobutyryl-CoA starter unit of myxalamid B

Myxalamids are potent inhibitors of the eukaryotic electron transport chain produced by different myxobacteria. Here, we describe the identification of the myxalamid biosynthesis gene cluster from Myxococcus xanthus. Additionally, new myxalamids (5-13) have been obtained by mutasynthesis from bkd mutants of M. xanthus and Stigmatella aurantiaca. Moreover, as these bkd mutants are still able to produce myxalamid B (2), the origin of the isobutyryl-CoA (IB-CoA) starter unit required for its biosynthesis has been determined. In a M. xanthus bkd mutant, IB-CoA originates from valine, but in S. aurantiaca this starter unit is derived from alpha-oxidation of iso-odd fatty acids, thereby connecting primary and secondary metabolism.     

Label-free optical detection and tracking of single virions bound to their receptors in supported membrane bilayers

We apply an interferometric optical detection scheme to image and track unlabeled single virions. Individual simian virus 40 virions and uninfectious virus-like particles were imaged on a glass substrate and on a supported membrane bilayer. Moreover, single unlabeled virions were tracked when bound to supported membrane bilayers via the viral receptor, the glycolipid GM1. The technology presented here promises to be generally applicable to studying the motion of unlabeled macromolecules on membranes.     

Essential fatty acid deficiency induces fatty acid desaturase expression in rat epididymis, but not in testis

On the molecular level, essential fatty acid deficiency (EFAD) has been associated with induced fatty acid (FA) desaturase expression and activity in several tissues. However, there seem to be exceptions. In the present study, we examine the effects of EFAD in the male rat genital tract, combining FA analysis, gene expression studies, and morphological evaluation of epididymal spermatozoa. When feeding 21-day-old Wistar rats, a fat-free diet for 6 weeks, an increase in 18:1n-9 and 20:3n-9 and a concomitant decrease in the 18:2n-6 and 20:4n-6 species are seen in testis, as well as in liver. However, with regard to desaturase expression the rat testis seems to be unresponsive to EFAD conditions, in contrast to other organs studied. In the sexually mature testis none of the desaturases (SCD1, SCD2, D5D, or D6D) are induced in response to lowered contents of polyunsaturated FAs. This also applies to caput epididymis, while EFAD sensitivity is regained in cauda epididymis, where the desaturases are upregulated. The FA profile of epididymal spermatozoa is increasingly affected by EFAD during the transport from testis to cauda epididymis. Furthermore, a significant increase in the number of abnormal spermatozoa is observed in cauda epididymis.     

Prognostic factors for chronic neck pain in persons with minor or moderate injuries in traffic accidents

Prognostic factors for chronic neck pain were identified in a prospective Norwegian insurance cohort comprising 636 persons with minor or moderate traffic injuries. One questionnaire was used at baseline and another at 3 years post-injury. Daily severe or very severe neck pain at three years follow up was defined as chronic neck pain. Eight significant independent prognostic factors for chronic neck pain were identified: (1) rear-end or frontal and rear-end collision, odds ratio (OR): 4.10 (95% confidence interval (CI): 1.72-10.82); (2) neck and/or shoulder pain before the accident, OR: 2.38 (95% CI: 1.07-5.37); (3) post-accident (a) memory and concentration problems, OR: 4.62 (95% CI: 1.99-11.20), (b) bodily tension, OR: 3.43 (95% CI: 1.49-8.42), (c) difficulties to climb stairs, OR: 5.03 (95% CI: 1.77-14.95), (d) difficulties to bend forward, OR: 4.85 (95% CI: 2.06-11.79), (e) difficulties to do heavy labour, OR: 3.70 (95% CI: 1.24-11.64); (4) beliefs in future work disability, OR: 2.64 (95% CI: 1.11-6.48). The results indicate that development of chronic neck pain is influenced by pre-accident neck and/or shoulder pain, the impact of the collision, as well as post-accident symptoms, perceived impaired function and pessimism for the future ability to work.     

Robot guided bolt tensioning tool with adaptive process control for the automated assembly of wind turbine rotor blade bearings

The three rotor blade bearings of a wind turbine hub are mounted to the rotor by several hundred bolted joints. Within this assembly process, a specific preload force has to be applied to these bolts in order to achieve a defined clamping force between the bearing and the rotor. Despite high manual labour intensity and safety concerns (platforms need to be raised to reach bolted joint at a height of 4 m), workers use hydraulic bolt tensioning cylinders which need to be threaded on each bolt individually. In order to automate this recurring assembly process, a robot guided bolt tensioning tool has been developed, which is part of a self-adaptive assembly system. Hence, we are able to locate each bolted joint, mount the bolt tensioning tool and apply the preload to each bolt of the bearing sequentially. In order to be flexible for different product variants and compensate the tolerances of large product dimensions in the wind turbine assembly, an adaptive process has been created. Therefore, the relevant parameters describing the product and assembly process are identified which can be adapted depending on the rotor hub type. Furthermore, the tolerance chain is analysed and improved by integrating measurement techniques to the new tool and using these sensors in the adaptive process control.     

Social and collaborative aspects of interaction with a service robot

To an increasing extent, robots are being designed to become a part of the lives of ordinary people. This calls for new models of the interaction between humans and robots, taking advantage of human social and communicative skills. Furthermore, human–robot relationships must be understood in the context of use of robots, and based on empirical studies of humans and robots in real settings. This paper discusses social aspects of interaction with a service robot, departing from our experiences of designing a fetch-and-carry robot for motion-impaired users in an office environment. We present the motivations behind the design of the Cero robot, especially its communication paradigm. Finally, we discuss experiences from a recent usage study, and research issues emerging from this work. A conclusion is that addressing only the primary user in service robotics is unsatisfactory, and that the focus should be on the setting, activities and social interactions of the group of people where the robot is to be used.