Micro‐fracture experiments on nanocomposite hard coatings

Physical or chemical vapor deposited nanocomposite thin films evoke much scientific interest due to their unusual combination of mechanical properties, such as high hardness, high elastic recovery, high elastic strain limit, and high tensile strength. One of the most frequently studied film systems in this context is titanium-silicon-nitride (Ti-Si-N). The self-organized nanostructure consists typically of TiN nanocrystals (nc) covered by an amorphous (a) Si3N4 tissue phases. While the exceptional high hardness of Ti-Si-N films and the underlying mechanisms have been studied extensively, less attention has been paid on the fracture toughness. Here we show experimental results of cantilever bending tests, performed on 2 µm thick reactive magnetron sputtered Ti-Si-N films. We found that nc-TiN/a-Si3N4 possesses a significantly higher fracture toughness as TiN, namely KIC values of up to 4.5±0.6 MPa√m in comparison with 1.9±0.4 MPa√m of TiN. This, in combination with a high hardness of 38±2 GPa (TiN: 26±1 GPa), a high fracture strength of up to around 6 GPa, as well as a high elastic recovery and flexibility is an ideal basis for high performance coatings, e.g., used for various industrial applications such as machining. The film nanostructure was carefully studied by independent X-ray diffraction, X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy

Supreme Court Amicus Brief Regarding Wyeth v. Diana Levine

Prominent in arguments opposing preemption of state tort law liability for alleged inadequacies in prescription drug labeling is the argument that such liability can complement FDA regulation by improving on a regulatory scheme that fails to provide adequate deterrence against the marketing of unsafe or inadequately labeled drugs. The premise of this argument is faulty. Fundamental principles of economics and numerous studies of FDA drug regulation reveal that FDA in fact errs on the side of overregulation of prescription drugs. Product liability litigation focused solely on one side of the prescription drug public health equation leads to further distortions of the drug approval and labeling process and exacerbates FDA's inherent overly cautious approach. Preemption of state tort law where it conflicts with FDA requirements will minimize these distortions and thereby maximize public health.Health and Safety, Other Topics

Annealing effect on the Fracture Toughness of CrN/TiN Superlattice Systems

Coherently grown nanolayered thin films are generally known for their superior mechanical properties, compared to their monolithically grown constituents. Recently, we have shown that CrN/TiN superlattice films exhibit a bilayer period dependent peak in fracture toughness KIC. We propose that a dominating factor influencing these mechanical properties is the interface constitution between the layers. To proof this concept we modified the interfaces of CrN/TiN superlattice thin films with a bilayer period Λ of 9 and 18 nm by vacuum annealing experiments at different temperatures. This treatment promotes interdiffusion between CrN and TiN layers, leading to the formation of “blurred” interfaces and further on to interphases (CrN and TiN form a solid solution), as well as the reduction of coherency strains in the interface region. To calculate the fracture toughness of our hard coatings, we performed in-situ micromechanical cantilever bending tests on the ex-situ vacuum annealed samples. As expected for coatings without an age hardening effect, the hardness H decreases with increasing annealing temperature for both superlattice systems. For Λ = 9 nm the fracture toughness experiences a similar reduction following predictions given by the empirical H/E criteria. However, the coating with Λ = 18 nm does not follow this criteria and exhibits a peak in fracture toughness for an annealing temperature of Ta = 700 °C

Gene Loss and Adaptation to Hominids Underlie the Ancient Origin of HIV-1

SummaryHIV-1 resulted from cross-species transmission of SIVcpz, a simian immunodeficiency virus that naturally infects chimpanzees. SIVcpz, in turn, is a recombinant between two SIV lineages from Old World monkeys. Lentiviral interspecies transmissions are partly driven by the evolution and capacity of viral accessory genes, such as vpx, vpr, and vif, to antagonize host antiviral factors, such as SAMHD1 and the APOBEC3 proteins. We show that vpx, which in other lentiviruses antagonizes SAMHD1, was deleted during the creation of SIVcpz. This genomic deletion resulted in the reconstruction of the overlapping vif gene by “overprinting,” creating a unique vif that overlaps in its 3′ end with the vpr gene and can antagonize hominid APOBEC3s. Moreover, passage of SIVs through chimpanzees facilitated the subsequent adaptation of HIV-1 to humans. Thus, HIV-1 originated through a series of gene loss and adaptation events that generated its chimpanzee precursor and lowered the species barrier to human infection

The evolution of HIV-1 and the origin of AIDS

The major cause of acquired immune deficiency syndrome (AIDS) is human immunodeficiency virus type 1 (HIV-1). We have been using evolutionary comparisons to trace (i) the origin(s) of HIV-1 and (ii) the origin(s) of AIDS. The closest relatives of HIV-1 are simian immunodeficiency viruses (SIVs) infecting wild-living chimpanzees (Pan troglodytes troglodytes) and gorillas (Gorilla gorilla gorilla) in west central Africa. Phylogenetic analyses have revealed the origins of HIV-1: chimpanzees were the original hosts of this clade of viruses; four lineages of HIV-1 have arisen by independent cross-species transmissions to humans and one or two of those transmissions may have been via gorillas. However, SIVs are primarily monkey viruses: more than 40 species of African monkeys are infected with their own, species-specific, SIV and in at least some host species, the infection seems non-pathogenic. Chimpanzees acquired from monkeys two distinct forms of SIVs that recombined to produce a virus with a unique genome structure. We have found that SIV infection causes CD4(+) T-cell depletion and increases mortality in wild chimpanzees, and so the origin of AIDS is more ancient than the origin of HIV-1. Tracing the genetic changes that occurred as monkey viruses adapted to infect first chimpanzees and then humans may provide insights into the causes of the pathogenicity of these viruses

Analysis of clogging in constructed wetlands using magnetic resonance

In this work we demonstrate the potential of permanent magnet based magnetic resonance sensors to monitor and assess the extent of pore clogging in water filtration systems. The performance of the sensor was tested on artificially clogged gravel substrates and on gravel bed samples from constructed wetlands used to treat wastewater. Data indicate that the spin lattice relaxation time is linearly related to the hydraulic conductivity in such systems. In addition, within biologically active filters we demonstrate the ability to determine the relative ratio of biomass to abiotic solids, a measurement which is not possible using alternative techniques

Relations of low contrast visual acuity, quality of life and multiple sclerosis functional composite: a cross-sectional analysis

Background: Although common and often disabling in multiple sclerosis (MS), visual dysfunction is currently not adequately accounted for in both clinical routine and MS trials. Sloan low contrast letter acuity (SLCLA) is a standardised chart-based measure of visual function particular at low contrast and has been suggested as additional visual component to the Multiple Sclerosis Functional Composite (MSFC). Here, we evaluate the relations between SLCLA, retinal integrity, MSFC, and quality of life (QoL) in MS patients. Methods: Cross-sectional analysis of retinal nerve fibre layer (RNFL) thickness, MSFC, SLCLA (2.5% and 1.25% contrast levels), visual evoked potentials, and QoL (Short Form (SF) 36, National Eye Institute Visual Functioning Questionnaire (NEIVFQ)) using baseline data of 92 MS patients from an ongoing prospective longitudinal trial. Relations between RNFL thickness or P100 latency and SLCLA were analysed using generalised estimating equations (GEE) accounting for intra-individual inter-eye dependencies and corrected for age, gender, and history of optic neuritis. Pearson’s correlations were used to assess relations between SLCLA, MSFC, and QoL. Results: SLCLA reflected RNFL thickness (p = 0.021) and P100 latency (p = 0.004) and predicted vision-related QoL, reflected by the NEIVFQ39 subscores “general vision” and “near activities” (p < 0.008 for both). SLCLA did not predict general QoL reflected by SF36. Implementing SLCLA into MSFC, thus creating a four-dimensional MSFC4, captured aspects of disability reflected by the NEIVFQ39 subscores “general vision” (r = 0.42, p < 0.0001) and “near activity” (r = 0.3, p = 0.014) which were not captured by standard MSFC3. Conclusions: SLCLA at 2.5% and 1.25% contrast levels correlates with retinal morphology and P100 latency and predicts some aspects of vision-related QoL in MS. More importantly, using a prospective cross-sectional approach we provide evidence that extending the MSFC by SLCLA as an additional visual component increases the performance of MSFC to capture MS-related disability. Longitudinal data on the relation between SLCLA, MSFC, and QoL will be available in the near future

Unusually Divergent Ubiquitin Genes and Proteins in Plasmodium Species

Ubiquitin is an extraordinarily highly conserved 76 amino acid protein encoded by three different types of gene, where the primary translation products are fusions either of ubiquitin with one of two ribosomal proteins (RPs) or of multiple ubiquitin monomers from head to tail. Here, we investigate the evolution of ubiquitin genes in mammalian malaria parasites (Plasmodium species). The ubiquitin encoded by the RPS27a fusion gene is highly divergent, as previously found in a variety of protists. However, we also find that two other forms of divergent ubiquitin sequence, each previously thought to be extremely rare, have arisen recently during the divergence of Plasmodium subgenera. On two occasions, in two distinct lineages, the ubiquitin encoded by the RPL40 fusion gene has rapidly diverged. In addition, in one of these lineages, the polyubiquitin genes have undergone a single codon insertion, previously considered a unique feature of Rhizaria. There has been disagreement whether the multiple ubiquitin coding repeats within a genome exhibit concerted evolution or undergo a birth-and-death process; the Plasmodium ubiquitin genes show clear signs of concerted evolution, including the spread of this codon insertion to multiple repeats within the polyubiquitin gene.</p