Design of a pulse power supply unit for micro-ECM

Electrochemical micro-machining (μECM) requires a particular pulse power supply unit (PSU) to be developed in order to achieve desired machining performance. This paper summarises the development of a pulse PSU meeting the requirements of μECM. The pulse power supply provides tens of nanosecond pulse duration, positive and negative bias voltages and a polarity switching functionality. It fulfils the needs for tool preparation with reversed pulsed ECM on the machine. Moreover, the PSU is equipped with an ultrafast overcurrent protection which prevents the tool electrode from being damaged in case of short circuits. The developed pulse PSU was used to fabricate micro-tools out of 170 μm WC-Co alloy shafts via micro-electrochemical turning and drill deep holes via μECM in a disk made of 18NiCr6. The electrolyte used for both processes was a mixture of sulphuric acid and NaNO3 aqueous solutions.The research reported in this paper is supported by the European Commission within the project “Minimizing Defects in Micro-Manufacturing Applications (MIDEMMA)” (FP7-2011-NMP-ICT-FoF-285614

Mood and transient cardiac dysfunction in everyday life

Emotion in daily life may be associated with transient myocardial ischemia, ventricular tachycardia and impaired autonomic function in cardiac patients, but the precise temporal sequence is unclear. Eighty-eight patients with suspected coronary artery disease underwent 24-h electrocardiographic monitoring, and affect was measured with the Day Reconstruction Method. Thirteen patients (15%) experienced one or more episodes of ST depression or ventricular tachycardia, nine of whom provided concurrent mood data. Mood and heart rate variability were analyzed for the 15 min before, during, and 15 min after each ST depression/ventricular tachycardia episode, and were compared with control periods not associated with cardiac dysfunction. Patients reported more negative mood in the 15 min preceding cardiac dysfunction compared with control periods (P = 0.02). Heart rate increased in the 5 min before cardiac dysfunction (P = 0.005), whereas low frequency heart rate variability was reduced at onset but not before cardiac dysfunction (P = 0.007). There were not changes in high frequency heart rate variability. This small study indicates that emotional state may contribute to vulnerability of cardiac dysfunction in everyday life

Design of an electrochemical micromachining machine

Electrochemical micromachining (μECM) is a non-conventional machining process based on the phenomenon of electrolysis. μECM became an attractive area of research due to the fact that this process does not create any defective layer after machining and that there is a growing demand for better surface integrity on different micro applications including microfluidics systems, stress-free drilled holes in automotive and aerospace manufacturing with complex shapes, etc. This work presents the design of a next generation μECM machine for the automotive, aerospace, medical and metrology sectors. It has three axes of motion (X, Y, Z) and a spindle allowing the tool-electrode to rotate during machining. The linear slides for each axis use air bearings with linear DC brushless motors and 2-nm resolution encoders for ultra precise motion. The control system is based on the Power PMAC motion controller from Delta Tau. The electrolyte tank is located at the rear of the machine and allows the electrolyte to be changed quickly. This machine features two process control algorithms: fuzzy logic control and adaptive feed rate. A self-developed pulse generator has been mounted and interfaced with the machine and a wire ECM grinding device has been added. The pulse generator has the possibility to reverse the pulse polarity for on-line tool fabrication.The research reported in this paper is supported by the European Commission within the project “Minimizing Defects in Micro-Manufacturing Applications (MIDEMMA)” (FP7-2011-NMPICT- FoF-285614)

Corner contributions to holographic entanglement entropy

The entanglement entropy of three-dimensional conformal field theories contains a universal contribution coming from corners in the entangling surface. We study these contributions in a holographic framework and, in particular, we consider the effects of higher curvature interactions in the bulk gravity theory. We find that for all of our holographic models, the corner contribution is only modified by an overall factor but the functional dependence on the opening angle is not modified by the new gravitational interactions. We also compare the dependence of the corner term on the new gravitational couplings to that for a number of other physical quantities, and we show that the ratio of the corner contribution over the central charge appearing in the two-point function of the stress tensor is a universal function for all of the holographic theories studied here. Comparing this holographic result to the analogous functions for free CFT's, we find fairly good agreement across the full range of the opening angle. However, there is a precise match in the limit where the entangling surface becomes smooth, i.e., the angle approaches $\pi$, and we conjecture the corresponding ratio is a universal constant for all three-dimensional conformal field theories. In this paper, we expand on the holographic calculations in our previous letter arXiv:1505.04804, where this conjecture was first introduced.Comment: 62 pages, 6 figures, 1 table; v2: minor modifications to match published version, typos fixe

Investigation on the competing effects of clay dispersion and matrix plasticisation for polypropylene/clay nanocomposites. Part I: morphology and mechanical properties

The key compatibiliser role of maleated polypropylene (MAPP) to improve the clay dispersability has been explicitly addressed in the fabrication process and material characterisation of polypropylene (PP)/clay nanocomposites. However, its matrix plasticiser role, which has been rarely mentioned, could adversely influence the excellent mechanical properties of such nanocomposites, resulting from the homogeneous clay dispersion. PP/clay nanocomposites in the presence of MAPP were prepared by twin screw extrusion and subsequently injection moulded with three typical material formulations in fixed parametric settings: (1) weight ratio (WR) of clay and MAPP, WR = 1:2; (2) MAPP content of 6 wt% and (3) clay content of 5 wt%. The morphological structures and mechanical properties of PP/clay nanocomposites were examined by using X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and universal mechanical testing. The further improvement of mechanical properties was evidently hindered with very inconsiderable alteration of morphological structures in terms of the clay dispersion level. This observation could be ascribed to the change of MAPP role from a compatibiliser to a plasticiser because of its excessive amount used above a certain saturation level, which was found in the range of 3–6 wt% in MAPP contents for the enhancements of tensile and flexural properties of PP/clay nanocomposites

Accreting Millisecond X-Ray Pulsars

Accreting Millisecond X-Ray Pulsars (AMXPs) are astrophysical laboratories without parallel in the study of extreme physics. In this chapter we review the past fifteen years of discoveries in the field. We summarize the observations of the fifteen known AMXPs, with a particular emphasis on the multi-wavelength observations that have been carried out since the discovery of the first AMXP in 1998. We review accretion torque theory, the pulse formation process, and how AMXP observations have changed our view on the interaction of plasma and magnetic fields in strong gravity. We also explain how the AMXPs have deepened our understanding of the thermonuclear burst process, in particular the phenomenon of burst oscillations. We conclude with a discussion of the open problems that remain to be addressed in the future.Comment: Review to appear in "Timing neutron stars: pulsations, oscillations and explosions", T. Belloni, M. Mendez, C.M. Zhang Eds., ASSL, Springer; [revision with literature updated, several typos removed, 1 new AMXP added

Higher Expression of CCL2, CCL4, CCL5, CCL21, and CXCL8 Chemokines in the Skin Associated with Parasite Density in Canine Visceral Leishmaniasis

Several previous studies correlated immunopathological aspects of canine visceral leishmaniasis (CVL) with tissue parasite load and/or the clinical status of the disease. Recently, different aspects of the immune response in Leishmania-infected dogs have been studied, particularly the profile of cytokines in distinct compartments. However, the role of chemokines in disease progression or parasite burdens of the visceralising species represents an important approach for understanding immunopathology in CVL. We found an increase in inflammatory infiltrate, which was mainly composed of mononuclear cells, in the skin of animals presenting severe forms of CVL and high parasite density. Our data also demonstrated that enhanced parasite density is positively correlated with the expression of CCL2, CCL4, CCL5, CCL21, and CXCL8. In contrast, there was a negative correlation between parasite density and CCL24 expression. These findings represent an advance in the knowledge of the involvement of skin inflammatory infiltrates in CVL and the systemic consequences and may contribute to developing a rational strategy for the design of new and more efficient prophylactic tools and immunological therapies against CVL

MicroRNA-122 Modulates the Rhythmic Expression Profile of the Circadian Deadenylase Nocturnin in Mouse Liver

Nocturnin is a circadian clock-regulated deadenylase thought to control mRNA expression post-transcriptionally through poly(A) tail removal. The expression of Nocturnin is robustly rhythmic in liver at both the mRNA and protein levels, and mice lacking Nocturnin are resistant to diet-induced obesity and hepatic steatosis. Here we report that Nocturnin expression is regulated by microRNA-122 (miR-122), a liver specific miRNA. We found that the 3′-untranslated region (3′-UTR) of Nocturnin mRNA harbors one putative recognition site for miR-122, and this site is conserved among mammals. Using a luciferase reporter construct with wild-type or mutant Nocturnin 3′-UTR sequence, we demonstrated that overexpression of miR-122 can down-regulate luciferase activity levels and that this effect is dependent on the presence of the putative miR-122 recognition site. Additionally, the use of an antisense oligonucleotide to knock down miR-122 in vivo resulted in significant up-regulation of both Nocturnin mRNA and protein expression in mouse liver during the night, resulting in Nocturnin rhythms with increased amplitude. Together, these data demonstrate that the normal rhythmic profile of Nocturnin expression in liver is shaped in part by miR-122. Previous studies have implicated Nocturnin and miR-122 as important post-transcriptional regulators of both lipid metabolism and circadian clock controlled gene expression in the liver. Therefore, the demonstration that miR-122 plays a role in regulating Nocturnin expression suggests that this may be an important intersection between hepatic metabolic and circadian control

Structure and function of a broad-specificity chitin deacetylase from <i>Aspergillus nidulans </i>FGSC A4

publishedVersio

Transcriptional profile of the homologous recombination machinery and characterization of the EhRAD51 recombinase in response to DNA damage in Entamoeba histolytica

<p>Abstract</p> <p>Background</p> <p>In eukaryotic and prokaryotic cells, homologous recombination is an accurate mechanism to generate genetic diversity, and it is also used to repair DNA double strand-breaks. <it>RAD52 </it>epistasis group genes involved in recombinational DNA repair, including <it>mre11, rad50, nsb1/xrs2, rad51, rad51c/rad57, rad51b/rad55, rad51d, xrcc2, xrcc3, rad52, rad54, rad54b/rdh54 </it>and <it>rad59 </it>genes, have been studied in human and yeast cells. Notably, the RAD51 recombinase catalyses strand transfer between a broken DNA and its undamaged homologous strand, to allow damaged region repair. In protozoan parasites, homologous recombination generating antigenic variation and genomic rearrangements is responsible for virulence variation and drug resistance. However, in <it>Entamoeba histolytica </it>the protozoan parasite responsible for human amoebiasis, DNA repair and homologous recombination mechanisms are still unknown.</p> <p>Results</p> <p>In this paper, we initiated the study of the mechanism for DNA repair by homologous recombination in the primitive eukaryote <it>E. histolytica </it>using UV-C (150 J/m²) irradiated trophozoites. DNA double strand-breaks were evidenced in irradiated cells by TUNEL and comet assays and evaluation of the EhH2AX histone phosphorylation status. In <it>E. histolytica </it>genome, we identified genes homologous to yeast and human RAD52 epistasis group genes involved in DNA double strand-breaks repair by homologous recombination. Interestingly, the <it>E. histolytica </it>RAD52 epistasis group related genes were differentially expressed before and after UV-C treatment. Next, we focused on the characterization of the putative recombinase EhRAD51, which conserves the typical architecture of RECA/RAD51 proteins. Specific antibodies immunodetected EhRAD51 protein in both nuclear and cytoplasmic compartments. Moreover, after DNA damage, EhRAD51 was located as typical nuclear <it>foci</it>-like structures in <it>E. histolytica </it>trophozoites. Purified recombinant EhRAD51 exhibited DNA binding and pairing activities and exchanging reactions between homologous strands <it>in vitro</it>.</p> <p>Conclusion</p> <p><it>E. histolytica </it>genome contains most of the RAD52 epistasis group related genes, which were differentially expressed when DNA double strand-breaks were induced by UV-C irradiation. In response to DNA damage, EhRAD51 protein is overexpressed and relocalized in nuclear <it>foci</it>-like structures. Functional assays confirmed that EhRAD51 is a <it>bonafide </it>recombinase. These data provided the first insights about the potential roles of the <it>E. histolytica </it>RAD52 epistasis group genes and EhRAD51 protein function in DNA damage response of this ancient eukaryotic parasite.</p