High-sensitivity and high-resolution low-energy ion scattering

Low-Energy Ion Scattering (LEIS or ISS) is used to selectively analyze the atomic composition of the outer atomic layer of surfaces. In addition, the spectrum gives (non-destructively) the in-depth distribution. Using a double toroidal energy analyzer with parallel energy detection and time-of-flight filtering a high sensitivity and mass resolution of LEIS is achieved. This is demonstrated for a highly dispersed catalyst of Pt/Au on γ-alumina. The improved depth resolution is illustrated for self-assembled monolayers of alkanethiols (12-20 carbon atoms) on gold. Even for these low Z carbon atoms a clear shift of 8 eV/carbon atom is observed (using 1.5 keV ⁴He⁺ ion scattering). This opens many new possibilities for studies of ultra-thin diffusion barriers, high-k dielectrics and biosensors.     

Potent Inhibition of Acid Sphingomyelinase by Phosphoinositide Analogues

The different mammalian sphingomyelinases are involved in cell regulation, apoptosis and inflammatory events. Recent reports suggest pharmacological potential especially for inhibitors of the acid sphingomyelinase. Phosphatidyl inositol‐3,5bisphosphate (PtdIns3,5P₂) is the most potent selective acid sphingomyelinase inhibitor known to date. In the present study, we synthesized analogues of PtdIns3,5P₂ for initial structure–activity‐relationship (SAR) studies. We identified an inhibitor that is easy to synthesize, that has superior chemical and biophysical properties when compared to PtdIns3,5P₂ and that should be stable against virtually all phospholipases. Last but not least, the new inhibitor partially protected cells from dexamethasone‐induced cell death.     

Vacuum-processed polyethylene as a dielectric for low operating voltage organic field effect transistors

We report on the fabrication and performance of vacuum-processed organic field effect transistors utilizing evaporated low-density polyethylene (LD-PE) as a dielectric layer. With C₆₀ as the organic semiconductor, we demonstrate low operating voltage transistors with field effect mobilities in excess of 4 cm²/Vs. Devices with pentacene showed a mobility of 0.16 cm²/Vs. Devices using tyrian Purple as semiconductor show low-voltage ambipolar operation with equal electron and hole mobilities of ～0.3 cm²/Vs. These devices demonstrate low hysteresis and operational stability over at least several months. Grazing-angle infrared spectroscopy of evaporated thin films shows that the structure of the polyethylene is similar to solution-cast films. We report also on the morphological and dielectric properties of these films. Our experiments demonstrate that polyethylene is a stable dielectric supporting both hole and electron channels.     

Design and Testing of a 2-DOF Ball Drive

Omnidirectional mobile robots offer interesting features for industrial and service applications, in particular, when operating in tight spaces. Compared to car-like nonholonomic vehicles, they provide a higher degree of maneuverability, and often require less complex path planning and control schemes. Three different types of holonomic wheels that enable omnidirectional motion have been proposed in literature: universal, Mecanum, and ball wheel mechanisms. A problem commonly associated with the first two wheel types is that they induce vibrations in the system due to the discontinuous contact points. In this article, a ball wheel mechanism with superior features including slip measurement, free-wheel modus and attrition sensing is presented. The first prototype was built using additive manufacturing. The requirements for the design and possible improvements for future versions are discussed. Based on the presented ball wheel drive, a design for an omnidirectional mobile robot platform driven by three redundant ball wheel units is proposed. The velocity kinematic model of this mobile base is also addressed. Moreover, motion planning for an individual ball drive is demonstrated by means of an online trajectory generation scheme. The pseudocode of the trajectory planning algorithm implemented in LabVIEW is then presented. Finally, the motion characteristics of the ball drive mechanism are tested and its functionality is evaluated in detail. Measurements obtained from these tests show that the slip between the ball wheel and the ground can be estimated quite accurately. Hence, it is expected that these improved dead-reckoning estimates will result in a higher positioning accuracy of the final base.     

Coating of carbon fibers with adhesion-promoting thin poly(acrylic acid) and poly(hydroxyethylmethacrylate) layers using electrospray ionization

Thin coatings of poly(acrylic acid) (PAA) and poly(hydroxyethylmethacrylate) (PHEMA) were deposited onto carbon fibers by means of the electrospray ionization (ESI) technique in ambient air. These high-molecular weight polymer layers were used as adhesion promoters in carbon fiber–epoxy resin composites. Within the ESI process, the carbon fibers were completely enwrapped with polymer in the upper 10 plies of a carbon fiber roving. As identified with scanning electron microscopy also shadowed fibers in a bundle as well as backsides of fiber rovings were pinhole-free coated with polymers (‘electrophoretic effect’). Under the conditions used, the layers have a granular structure. Residual solvent was absent in the deposit. PAA and PHEMA films did not show any changes in composition and structure in comparison with the original polymers as analyzed by X-ray photo-electron spectroscopy and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Single-fiber pullout tests of coated fibers embedded in epoxy resin showed significantly increased interfacial shear strength. It is assumed that chemical bonds between carbon fiber poly(acrylic acid) and epoxy resin contribute significantly to the improved interactions.     

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Systematic review and quality assessment of economic evaluation studies of injury prevention

Objective

To review and assess the quality of economic evaluation studies on injury prevention measures.

Design

Systematic review.

Data sources

Electronic databases searched included Medline (Pubmed), EMBASE, Web of Science, PsycINFO, and Safetylit.

Inclusion criteria

Empirical studies published in English in international peer-reviewed journals in the period 1998–2009. The subject of the study was economic evaluation of prevention of unintentional injury. Cost-effectiveness (CEA), cost-benefit (CBA) and cost utility (CUA) analyses were included.

Methods

Methodological details, study designs, and analysis and interpretation of results of the included articles were reviewed and extracted into summary tables. Study quality was judged using the criteria recommended by the Panel on cost-effectiveness in health and medicine and the British Medical Journal (BMJ) checklist for economic evaluations.

Results

Forty-eight studies met the inclusion criteria of our review. Interventions assessed most frequently were hip protectors and exercise programs for the elderly. A wide variety of methodological approaches was found, including differences in type of economic evaluation, perspective, time horizon, study design, cost categories, effect outcomes, and adjustments for timing and uncertainty used. The majority of studies performed a cost-effectiveness analysis from a societal perspective with a time horizon of one to five years, in which the effect was expressed in terms of injuries prevented and only direct health care costs were included. Most studies deviated from one or more of the Panel recommendations or BMJ guidelines; e.g. not adopting the societal perspective, not including all relevant costs, no incremental analysis.

Conclusions

This review has shown that approaches to economic evaluation of injury prevention vary widely and most studies do not fulfill methodological rigour. Improving quality and harmonization of economic evaluation studies in the field of injury prevention is needed. One way of achieving this would be to establish international guidelines on economic evaluation for injury prevention interventions, based on established economic evaluation checklists, to assist researchers in the design and reporting of economic evaluations.     

Design and synthesis of novel di- and triblock amphiphilic polyelectrolytes: Improving salt-induced viscosity reduction of water solutions for potential application in enhanced oil recovery

In the present study, three different block copolymers based on styrene, tert-butyl methacrylate, and glycidyl methacrylate (GMA) were synthesized via sequential atom transfer radical polymerization. The addition of the GMA block was found to be best performed at 60°C. The polymers were then hydrolyzed and neutralized, to afford amphiphilic block copolymers, and the rheological properties of their aqueous solutions were measured, in order to investigate solution properties relevant for enhanced oil recovery, as a function of the polymer structure. It was observed that these polymers behave as thickening agents with shear thinning behavior. As expected, the polymers were sensitive to the presence of salt, as lower viscosities were recorded in saline water. However, the viscosity is less affected by high salinity, when compared to previously studied analogous diblock systems. In the best case, the viscosity only decreased by a factor of 1.8 upon salt addition whereas it decreased by a factor of 10 in previously reported non-GMA containing polymers. Finally, thermo-responsive behavior was found for one of the synthesized polymers. In particular, a hydrolyzed triblock poly[styrene-b-tert-butyl methacrylate-b-glycidyl methacrylate], which synthesis is reported here for the first time, showed a thermothickening behavior, promising for the intended application in oil recovery.