Texture-Governed Cell Response to Severely Deformed Titanium

The phenomenon of superior biological behavior , r it observed in titanium processed by an unconventional severe plastic deformation method, that is, hydrostatic extrusion, has been described within the present study. In doing so, specimens varying significantly in the crystallographic orientation of grains, yet exhibiting comparable grain refinement, were meticulously investigated. The aim was to find the clear origin of enhanced biocompatibility of titanium-based materials, having microstructures scaled down to the submicron range. Texture, microstructure, and surface characteristics, that is, wettability, roughness, and chemical composition, were examined as well as protein adsorption tests and cell response studies were carried out. It has been concluded that, irrespective of surface properties and mean grain size, the (10 (1) over bar0) crystallographic plane favors endothelial cell attachment on the surface of the severely deformed titanium. Interestingly, an enhanced albumin, fibronectin, and serum adsorption as well as dearly directional growth of the cells with preferentially oriented cell nuclei have been observed on the surfaces having (0001) planes exposed predominantly. Overall, the biological response of titanium fabricated by severe plastic deformation techniques is derived from the synergistic effect of surface irregularities, being the effect of refined microstructures, surface chemistry, and crystallographic orientation of grains rather than grain refinement itself

Insights into the Transposable Mobilome of Paracoccus spp. (Alphaproteobacteria)

Several trap plasmids (enabling positive selection of transposition events) were used to identify a pool of functional transposable elements (TEs) residing in bacteria of the genus Paracoccus (Alphaproteobacteria). Complex analysis of 25 strains representing 20 species of this genus led to the capture and characterization of (i) 37 insertion sequences (ISs) representing 9 IS families (IS3, IS5, IS6, IS21, IS66, IS256, IS1182, IS1380 and IS1634), (ii) a composite transposon Tn6097 generated by two copies of the ISPfe2 (IS1634 family) containing two predicted genetic modules, involved in the arginine deiminase pathway and daunorubicin/doxorubicin resistance, (iii) 3 non-composite transposons of the Tn3 family, including Tn5393 carrying streptomycin resistance and (iv) a transposable genomic island TnPpa1 (45 kb). Some of the elements (e.g. Tn5393, Tn6097 and ISs of the IS903 group of the IS5 family) were shown to contain strong promoters able to drive transcription of genes placed downstream of the target site of transposition. Through the application of trap plasmid pCM132TC, containing a promoterless tetracycline resistance reporter gene, we identified five ways in which transposition can supply promoters to transcriptionally silent genes. Besides highlighting the diversity and specific features of several TEs, the analyses performed in this study have provided novel and interesting information on (i) the dynamics of the process of transposition (e.g. the unusually high frequency of transposition of TnPpa1) and (ii) structural changes in DNA mediated by transposition (e.g. the generation of large deletions in the recipient molecule upon transposition of ISPve1 of the IS21 family). We also demonstrated the great potential of TEs and transposition in the generation of diverse phenotypes as well as in the natural amplification and dissemination of genetic information (of adaptative value) by horizontal gene transfer, which is considered the driving force of bacterial evolution

High-level programming of embedded hard real-time devices

While managed languages such as C # and Java have become quite popular in enterprise computing, they are still considered unsuitable for hard real-time systems. In particular, the presence of garbage collection has been a sore point for their acceptance for low-level system programming tasks. Realtime extensions to these languages have the dubious distinction of, at the same time, eschewing the benefits of highlevel programming and failing to offer competitive performance. The goal of our research is to explore the limitations of high-level managed languages for real-time systems programming. To this end we target a real-world embedded platform, the LEON3 architecture running the RTEMS real-time operating system, and demonstrate the feasibility of writing garbage collected code in critical parts of embedded systems. We show that Java with a concurrent, real-time garbage collector, can have throughput close to that of C programs and comes within 10 % in the worst observed case on realistic benchmark. We provide a detailed breakdown of the costs of Java features and their execution times and compare to real-time and throughput-optimized commercial Java virtual machines

Coating of Tungsten Wire with Ni/Al Multilayers for Self-Healing Applications

Self-healing materials are able to partially or completely reverse the damage inflicted on them. The possibility of self-healing mechanical and chemical failures that occur during service will improve the lifetime and reliability of structural materials. For this purpose, two main steps must be considered: (i) detection, and (ii) repairing (healing) of cracks. The exothermic character of reactive multilayers has potential for self-healing applications, namely in the healing step. In this context, Ni(V)/Al multilayer thin films were deposited onto tungsten wires by magnetron sputtering from two targets. A detailed microstructural characterization was carried out by scanning and transmission electron microscopy after deposition, as well as after ignition by applying an electrical discharge. The as-deposited films presented an irregular layered structure with local defects not observed for flat substrates, although Ni- and Al-rich nanolayers could be distinguished. The as-reacted films were constituted by Al3Ni2 grains with Al3V phase at the grain boundaries. In order to use reactive multilayers for self-healing purposes, the heat released must be maximised by improving the microstructure of the nanolayered films. Nevertheless, after ignition, the Ni(V)/Al multilayer films deposited onto W wire underwent a self-sustained reaction, releasing heat

Effect of Deposition Parameters on the Reactivity of Al/Ni Multilayer Thin Films

Nanoscale multilayers can be used as highly localized heat sources, making them attractive for several applications, in particular for joining and as igniters. Over the last decades, academia and industry have given particular emphasis to nanoscale multilayers from the Ni–Al system. In this study, Al/Ni (V) multilayer thin films with periods of nominally 25 and 50 nm (bilayer thickness) and near equiatomic average stoichiometry were produced by d.c. magnetron sputtering from Al (99.999% pure) and Ni (93 wt % Ni, 7 wt % V) targets (vanadium was added to the Ni target to make it non-magnetic). Deposition parameters such as the substrate rotation speed and substrate bias were varied in order to evaluate their e ect on the reactivity of the multilayers. The influence of in situ ion bombardment of the multilayer thin films was also studied. Phase identification was carried out by X-ray di raction, while the microstructure was analyzed in detail by transmission electron microscopy, distinguishing alternating layers throughout the entire thickness of the films. Although the films mainly consist of Al- and Ni-rich layers, the presence of the Al3Ni intermetallic phase was detected, except in the multilayers produced with the ion gun switched on during the deposition process. The ion bombardment, as well as the increase of the substrate bias, promote some microstructural disorder and thus a ect the multilayers’ reactivity

Development of Actuators for Repairing Cracks by Coating W Wires with Reactive Multilayers

The aim of this research work was to optimize the coating of tungsten wires with reactive multilayer thin films and promote an exothermic self-propagating reaction. The ultimate goal is to use this heat to liquify low melting temperature materials, and thus block crack propagation in metallic materials. Ni/Me (Me = Al, Ti) multilayers were deposited by a DC (direct current) magnetron sputtering onto tungsten wires with diameters of 0.05 and 0.20 mm. The depositions were carried out to obtain films with near equiatomic average chemical composition and a modulation period (bilayer thickness) between 20 and 50 nm. The cross-section of the films was analyzed using electron microscopy before and after electrical ignition. A new substrate holder was developed to improve the quality of the Al/Ni films, allowing a reduction in the defects previously observed. The Ni/Ti thin films showed no discernible defects, regardless of the substrate holder. However, after ignition, the Ni + Ti reaction occurred in a non-self-propagating mode. Passing an electric current through a wire (ϕ = 0.05 mm) coated with an Al/Ni thin film, promoted a flash of light that was associated with the start of a self-propagating reaction. The reaction product was a B2-AlNi intermetallic phase. W wires coated with reactive multilayers may contribute to crack filling, and have potential to be self-healing actuators

Schematic structure of the REP modules analyzed in this study.

<p>The color-coded keys show the species and strain of origin of each plasmid (circles) and identified direct repeats (DRs), inverted repeats (IRs) as well as predicted DnaA and IHF binding sites (mixed shapes). The sequences of the iteron-like DRs are presented next to the relevant diagrams with a consensus sequence shown for DRs of plasmids with related REP modules. Blue arrows indicate the <i>rep</i> genes and their transcriptional orientation. Specific motifs identified within the aa sequences of the Rep proteins are indicated by colored rounded bars. A+T and G+C indicate DNA regions of lower or higher than average G+C content, respectively. The components of the REP modules are not shown to scale.</p

Plasmids of Carotenoid-Producing <i>Paracoccus</i> spp. (<i>Alphaproteobacteria</i>) - Structure, Diversity and Evolution

<div><p>Plasmids are components of many bacterial genomes. They enable the spread of a large pool of genetic information via lateral gene transfer. Many bacterial strains contain mega-sized replicons and these are particularly common in <i>Alphaproteobacteria</i>. Considerably less is known about smaller alphaproteobacterial plasmids. We analyzed the genomes of 14 such plasmids residing in 4 multireplicon carotenoid-producing strains of the genus <i>Paracoccus</i> (<i>Alphaproteobacteria</i>): <i>P. aestuarii</i> DSM 19484, <i>P. haeundaensis</i> LG P-21903, <i>P. marcusii</i> DSM 11574 and <i>P. marcusii</i> OS22. Comparative analyses revealed mosaic structures of the plasmids and recombinational shuffling of diverse genetic modules involved in (i) plasmid replication, (ii) stabilization (including toxin-antitoxin systems of the <i>relBE</i>/<i>parDE</i>, <i>tad</i>-<i>ata</i>, <i>higBA</i>, <i>mazEF</i> and <i>toxBA</i> families) and (iii) mobilization for conjugal transfer (encoding relaxases of the Mob_Q, Mob_P or Mob_V families). A common feature of the majority of the plasmids is the presence of AT-rich sequence islets (located downstream of <i>exc1</i>-like genes) containing genes, whose homologs are conserved in the chromosomes of many bacteria (encoding e.g. RelA/SpoT, SMC-like proteins and a retron-type reverse transcriptase). The results of this study have provided insight into the diversity and plasticity of plasmids of <i>Paracoccus</i> spp., and of the entire <i>Alphaproteobacteria</i>. Some of the identified plasmids contain replication systems not described previously in this class of bacteria. The composition of the plasmid genomes revealed frequent transfer of chromosomal genes into plasmids, which significantly enriches the pool of mobile DNA that can participate in lateral transfer. Many strains of <i>Paracoccus</i> spp. have great biotechnological potential, and the plasmid vectors constructed in this study will facilitate genetic studies of these bacteria. </p> </div

The plasmids containing the DIY cassettes constructed in this study.

<p>A. pKRP-DIY plasmids. B. pVIV mobilizable shuttle vectors. The plasmids contain DIY_AES7 and DIY_MOS6 cassettes composed of REP modules (of plasmids pAES7 and pMOS6, respectively), a Km^r gene and a MOB module derived from BHR plasmid RK2. B – BamHI, E – EcoRI, H – HindIII, K – KpnI, P – PstI, Sc – SacI, Sh – SphI, Sl – SalI, Sm – SmaI, X – XbaI. </p