A 10B-based neutron detector with stacked Multiwire Proportional Counters and macrostructured cathodes

We present the results of the measurements of the detection efficiency for a 4.7 \r{A} neutron beam incident upon a detector incorporating a stack of up to five MultiWire Proportional Counters (MWPC) with Boron-coated cathodes. The cathodes were made of Aluminum and had a surface exhibiting millimeter-deep V-shaped grooves of 45{\deg}, upon which the thin Boron film was deposited by DC magnetron sputtering. The incident neutrons interacting with the converter layer deposited on the sidewalls of the grooves have a higher capture probability, owing to the larger effective absorption film thickness. This leads to a higher overall detection efficiency for the grooved cathode when compared to a cathode with a flat surface. Both the experimental results and the predictions of the GEANT4 model suggests that a 5-counter detector stack with coated grooved cathodes has the same efficiency as a 7-counter stack with flat cathodes. The reduction in the number of counters in the stack without altering the detection efficiency will prove highly beneficial for large-area position-sensitive detectors for neutron scattering applications, for which the cost-effective manufacturing of the detector and associated readout electronics is an important objective. The proposed detector concept could be a technological option for one of the new chopper spectrometers and other instruments planned to be built at the future European Spallation Source in Sweden. These results with macrostructured cathodes generally apply not just to MWPCs but to other gaseous detectors as well.Comment: 14 pages, 9 figure

Effects of the physical properties of water masses on microbial activity during an Ice Shelf Water overflow in the central Ross Sea

During the 1997-98 Italian Expedition to Antarctica a five-day mesoscale experiment was carried out on the continental shelf-break in the central Ross Sea. This area is oceanographically characterized by shelf/slope interactions, through intense mixing processes, between the Circumpolar Deep Water (CDW) and the Ice Shelf Water (ISW), coming from beneath the Ross Ice Shelf and spilling over the shelf edge. The export of dense shelf waters is of crucial importance not only for the mass balance of the basin, but also for carbon export from the upper layers into the abyssal ones. The study investigated how the ISW interactions with the CDW may influence bacterial metabolism during an ISW downslope event. In particular, what effect does this have on the bacterial activities related to the utilization and transformation of the organic carbon substrate (ectoenzymatic activities, carbon production, growth rate) within the ISW and the CDW cores? Our data show that in the CDW the metabolic response was to increase the biomass and enzymes were less active due to a higher nutritional value for the substrate. In the ISW the bacterial metabolic activity shifted towards degradative processes. These results suggest differences in the quality of the organic carbon pool with a greater concentration of labile organic matter in the CDW and of low-degradable compounds in the ISW. The use of microbial parameters seems to be very promising in the evaluation of the carbon export during mixing processes, when the refractory fraction of the organic carbon pool might play a key role

The new small-angle neutron scattering instrument SANS-1 at MLZ—characterization and first results

AbstractA thorough characterization of the key features of the new small-angle neutron scattering instrument SANS-1 at MLZ, a joint project of Technische Universität München and Helmholtz Zentrum Geesthacht, is presented. Measurements of the neutron beam profile, divergency and flux are given for various positions along the instrument including the sample position, and agree well with Monte Carlo simulations of SANS-1 using the program McStas. Secondly, the polarization option of SANS-1 is characterized for a broad wavelength band. A key feature of SANS-1 is the large accessible Q-range facilitated by the sideways movement of the detector. Particular attention is hence paid to the effects that arise due to large scattering angles on the detector where a standard cos3 solid angle correction is no longer applicable. Finally the performance of the instrument is characterized by a set of standard samples

INFECTION AND TRANSFORMATION OF MOUSE PERITONEAL MACROPHAGES BY SIMIAN VIRUS 40

The stimulation of DNA synthesis in mouse (C57BL) macrophages explanted in vitro was demonstrated after treatment with conditioned medium or infection with SV40. In the latter case, induction of SV40 T antigen was detected before TdR-3H incorporation. Even though all macrophages were infected (T antigen-positive), they exhibited considerable pleomorphism, accompanied by functional differences. Permanent lines of SV40-transformed macrophages were eventually established, and one clone was isolated which replicates indefinitely and has many properties of primary macrophages: high acid phosphatase and phagocytic activity, lysozyme production, and specific antigenic determinants. These cells differ from normal macrophages in that they contain the SV40 genome, can be trypsinized, and do not require conditioned medium for continued replication

Quantum Tunneling in the Wigner Representation

Time dependence for barrier penetration is considered in the phase space. An asymptotic phase-space propagator for nonrelativistic scattering on a one - dimensional barrier is constructed. The propagator has a form universal for various initial state preparations and local potential barriers. It is manifestly causal and includes time-lag effects and quantum spreading. Specific features of quantum dynamics which disappear in the standard semi-classical approximation are revealed. The propagator may be applied to calculation of the final momentum and coordinate distributions, for particles transmitted through or reflected from the potential barrier, as well as for elucidating the tunneling time problem.Comment: 18 pages, LATEX, no figure

LA BACTERICIDIE DES NEUTROPHILES : MECANISMES CELLULAIRES ET MOLECULAIRES ET LEURS DYSFONCTIONS

Microbicidal activity of neutrophils requires the NADPH oxidase dependent reactive oxygen species (ROS) production and myeloperoxidase (MPO)-H2O2-halide system-catalyzed halogenations (oxidative mechanisms) and the release of granular proteins into the phagosomal lumen (non oxidative mechanisms). The long-established direct role of ROS and MPO has been recently questioned. In this work, using our improved method to assess microbicidal activity, we have re-examined the role of the diverse mechanisms proposed to be involved in the antimicrobial activity of neutrophils. We show that the NADPH oxidase activity is indispensable for the killing of certain microorganisms (e.g. Staphylococcus aureus, Candida albicans) but not of others (e.g. Escherichia coli) which are efficiently killed even in the absence of a respiratory burst. Our data also indicate that NADPH oxidase-dependent killing of S. aureus and C. albicans is largely dependent on MPO. Alkalinization of phagosomal pH and K+ fluxes do not appear to significantly contribute to the killing of these microorganisms. K+ channels activity may account for the partial recovery of killing observed in MPO-deficient neutrophils at long times of incubation.We have also investigated the neutrophils’ microbicidal mechanisms in a cellular model, the human myelomonoblastic cellular line inducible in granulocytes, PLB-985. The ROS production in PLB-985 cells stimulated by opsonized microorganisms is very weak compared to human neutrophils, but sustains a NADPH oxidase dependent killing activity of S. aureus and C. albicans similar to PMN after short times of incubation (<10 min). However, the killing activity of the PLB cells is abolished after long times of incubation. NADPH oxidase independent killing of E. coli is also defective. The ROS overproduction of the mutant DloopNox4-Nox2 (in these cells, the D-loop of Nox2 was replaced by the D-loop of its homolog Nox4) after soluble and particulate agonists dependent activation does not increase their microbicidal power. The weak killing activity of the PLB-985 cellular line can be explained by the faint amounts of cytochrome b558 and by the more or less lack of granular proteins content (MPO, elastase, cathepsine G, lactoferrine, lysozyme, MMP8 and MMP9) involved in the microbicidal event. In conclusion, in PLB-985 DMF-differentiated cells, the oxygen dependent and independent mechanisms are both defective. A lack of NADPH oxidase complex results in a rare inherited disorder, the chronic granulomatose disease (CGD). We characterized an atypical and extremely rare case of CGD: the X91- variant: the new identified point mutation in the CYBB gene promoter (insertion of a T at position -54T/-56T) appeared to be related to the loss of association of ets transcription factors within this region, prevent the normally functional expression of the gene and finally, correlate with the low NADPH oxidase activity. The residual respiratory burst supported no killing of S. aureus and C. albicans, in vitro, and is not sufficient to protect the patient against severe and recurrent infections.L’élimination des microorganismes par les neutrophiles (PMN) est mediée par l’activité des formes réactives de l’oxygène (FRO), produites suite à l’activation de la NADPH oxydase, dont l’efficacité est sensiblement augmentée par la myélopéroxydase, MPO, (mécanismes oxydatifs) et par l’action des protéines bactéricides contenues dans les granules cytoplasmiques (mécanismes non oxydatifs). L’implication directe des FRO et de la MPO dans la bactéricidie des PMN a été récemment remise en question. Nous nous sommes proposés de réexaminer les mécanismes impliqués dans la bactéricidie des neutrophiles sur la base des nouvelles hypothèses récemment proposées en appliquant une méthode de mesure du « killing » des microorganismes que nous avons récemment mise au point et qui permet une estimation plus correcte de la bactéricidie. Nous avons démontré que l’activité NADPH oxydase est indispensable pour le « killing » de certains microorganismes (S. aureus et C. albicans) mais pas pour d’autres (E. coli) qui sont efficacement éliminés même en l’absence du burst respiratoire. Les flux d’ions K+ et l’alcalinisation du pH intraphagosomale, induits par l’activation du complexe oxydase, ne sont pas nécessaires au killing de S. aureus et C. albicans, microorganismes dont la bactéricidie NADPH oxydase dépendante est mediée presque exclusivement par la MPO. Les courants des ions K+, à travers des canaux BKCa-like, semblent être responsables du killing résiduel des PMN MPO déficients, après une longue incubation. Nous avons aussi étudié les mécanismes impliqués dans la bactéricidie des PMN en utilisant comme modèle cellulaire la lignée PLB-985 différentiable en « pseudo-neutrophiles ». Nous avons prouvé que la réponse de ces cellules aux stimuli particulaires est sensiblement plus faible par rapport aux PMN. Ce burst respiratoire support e une bactéricidie comparable à celles des PMN pour des temps courts d’incubation (<10 min) vis-à-vis des microorganismes sensibles aux mécanismes de « killing » oxygène-dépendants (S. aureus et C. albicans); toutefois, en prolongeant les temps d’incubation, le pouvoir bactéricides ce ces cellules est abolit. Le « killing » NADPH oxydase indépendant d’E. coli est aussi partiellement déficitaire. La superproduction de FRO mise en évidence dans les cellules mutantes PLB-985 DloopNox4-Nox2 (où la deuxième boucle intracellulaire de Nox2 a été remplacée par celle de l’oxydase homologue Nox4) en réponse aux stimuli solubles et particulaires n’est pas accompagnée par une augmentation du « killing ». Le faible pouvoir bactéricide de cette lignée cellulaire est du au contenu réduit en cytochrome b558 (un dixième par rapport aux PMN) et aux défauts plus ou moins importants des protéines granulaires (MPO, elastase, cathepsine G, lactoferrine, lysozyme, MMP8 et MMP9) impliquées dans le processus de bactéricidie: dans les cellules PLB-985 différentiées au DMF, les mécanismes bactéricides oxygènes dépendants et indépendants sont donc tous deux compromis.Le dysfonctionnement du complexe NADPH oxydase est à la base d’une maladie génétique rare, la granulomatose septique chronique (CGD). Nous nous sommes intéressés à la caractérisation d’un cas atypique de CGD, la forme X91-. Nous avons démontré que la nouvelle mutation identifiée (insertion d’un T en position -54T/-56T) compromet l’association des facteurs de transcription ets avec la région promotrice, empêche, par conséquence, l’expression normale du gène dans les neutrophiles et détermine une activité oxydase réduite. Ce burst respiratoire résiduel (6% du control) n’est pas suffisante pour soutenir, in vitro, une activité de « killing » vis-à-vis de S. aureus et C. albicans ni pour protéger le patient des infections sévères et récidivantes

LA BACTERICIDIE DES NEUTROPHILES : MECANISMES CELLULAIRES ET MOLECULAIRES ET LEURS DYSFONCTIONS

Microbicidal activity of neutrophils requires the NADPH oxidase dependent reactive oxygen species (ROS) production and myeloperoxidase (MPO)-H2O2-halide system-catalyzed halogenations (oxidative mechanisms) and the release of granular proteins into the phagosomal lumen (non oxidative mechanisms). The long-established direct role of ROS and MPO has been recently questioned. In this work, using our improved method to assess microbicidal activity, we have re-examined the role of the diverse mechanisms proposed to be involved in the antimicrobial activity of neutrophils. We show that the NADPH oxidase activity is indispensable for the killing of certain microorganisms (e.g. Staphylococcus aureus, Candida albicans) but not of others (e.g. Escherichia coli) which are efficiently killed even in the absence of a respiratory burst. Our data also indicate that NADPH oxidase-dependent killing of S. aureus and C. albicans is largely dependent on MPO. Alkalinization of phagosomal pH and K+ fluxes do not appear to significantly contribute to the killing of these microorganisms. K+ channels activity may account for the partial recovery of killing observed in MPO-deficient neutrophils at long times of incubation.We have also investigated the neutrophils’ microbicidal mechanisms in a cellular model, the human myelomonoblastic cellular line inducible in granulocytes, PLB-985. The ROS production in PLB-985 cells stimulated by opsonized microorganisms is very weak compared to human neutrophils, but sustains a NADPH oxidase dependent killing activity of S. aureus and C. albicans similar to PMN after short times of incubation (<10 min). However, the killing activity of the PLB cells is abolished after long times of incubation. NADPH oxidase independent killing of E. coli is also defective. The ROS overproduction of the mutant DloopNox4-Nox2 (in these cells, the D-loop of Nox2 was replaced by the D-loop of its homolog Nox4) after soluble and particulate agonists dependent activation does not increase their microbicidal power. The weak killing activity of the PLB-985 cellular line can be explained by the faint amounts of cytochrome b558 and by the more or less lack of granular proteins content (MPO, elastase, cathepsine G, lactoferrine, lysozyme, MMP8 and MMP9) involved in the microbicidal event. In conclusion, in PLB-985 DMF-differentiated cells, the oxygen dependent and independent mechanisms are both defective. A lack of NADPH oxidase complex results in a rare inherited disorder, the chronic granulomatose disease (CGD). We characterized an atypical and extremely rare case of CGD: the X91- variant: the new identified point mutation in the CYBB gene promoter (insertion of a T at position -54T/-56T) appeared to be related to the loss of association of ets transcription factors within this region, prevent the normally functional expression of the gene and finally, correlate with the low NADPH oxidase activity. The residual respiratory burst supported no killing of S. aureus and C. albicans, in vitro, and is not sufficient to protect the patient against severe and recurrent infections.L’élimination des microorganismes par les neutrophiles (PMN) est mediée par l’activité des formes réactives de l’oxygène (FRO), produites suite à l’activation de la NADPH oxydase, dont l’efficacité est sensiblement augmentée par la myélopéroxydase, MPO, (mécanismes oxydatifs) et par l’action des protéines bactéricides contenues dans les granules cytoplasmiques (mécanismes non oxydatifs). L’implication directe des FRO et de la MPO dans la bactéricidie des PMN a été récemment remise en question. Nous nous sommes proposés de réexaminer les mécanismes impliqués dans la bactéricidie des neutrophiles sur la base des nouvelles hypothèses récemment proposées en appliquant une méthode de mesure du « killing » des microorganismes que nous avons récemment mise au point et qui permet une estimation plus correcte de la bactéricidie. Nous avons démontré que l’activité NADPH oxydase est indispensable pour le « killing » de certains microorganismes (S. aureus et C. albicans) mais pas pour d’autres (E. coli) qui sont efficacement éliminés même en l’absence du burst respiratoire. Les flux d’ions K+ et l’alcalinisation du pH intraphagosomale, induits par l’activation du complexe oxydase, ne sont pas nécessaires au killing de S. aureus et C. albicans, microorganismes dont la bactéricidie NADPH oxydase dépendante est mediée presque exclusivement par la MPO. Les courants des ions K+, à travers des canaux BKCa-like, semblent être responsables du killing résiduel des PMN MPO déficients, après une longue incubation. Nous avons aussi étudié les mécanismes impliqués dans la bactéricidie des PMN en utilisant comme modèle cellulaire la lignée PLB-985 différentiable en « pseudo-neutrophiles ». Nous avons prouvé que la réponse de ces cellules aux stimuli particulaires est sensiblement plus faible par rapport aux PMN. Ce burst respiratoire support e une bactéricidie comparable à celles des PMN pour des temps courts d’incubation (<10 min) vis-à-vis des microorganismes sensibles aux mécanismes de « killing » oxygène-dépendants (S. aureus et C. albicans); toutefois, en prolongeant les temps d’incubation, le pouvoir bactéricides ce ces cellules est abolit. Le « killing » NADPH oxydase indépendant d’E. coli est aussi partiellement déficitaire. La superproduction de FRO mise en évidence dans les cellules mutantes PLB-985 DloopNox4-Nox2 (où la deuxième boucle intracellulaire de Nox2 a été remplacée par celle de l’oxydase homologue Nox4) en réponse aux stimuli solubles et particulaires n’est pas accompagnée par une augmentation du « killing ». Le faible pouvoir bactéricide de cette lignée cellulaire est du au contenu réduit en cytochrome b558 (un dixième par rapport aux PMN) et aux défauts plus ou moins importants des protéines granulaires (MPO, elastase, cathepsine G, lactoferrine, lysozyme, MMP8 et MMP9) impliquées dans le processus de bactéricidie: dans les cellules PLB-985 différentiées au DMF, les mécanismes bactéricides oxygènes dépendants et indépendants sont donc tous deux compromis.Le dysfonctionnement du complexe NADPH oxydase est à la base d’une maladie génétique rare, la granulomatose septique chronique (CGD). Nous nous sommes intéressés à la caractérisation d’un cas atypique de CGD, la forme X91-. Nous avons démontré que la nouvelle mutation identifiée (insertion d’un T en position -54T/-56T) compromet l’association des facteurs de transcription ets avec la région promotrice, empêche, par conséquence, l’expression normale du gène dans les neutrophiles et détermine une activité oxydase réduite. Ce burst respiratoire résiduel (6% du control) n’est pas suffisante pour soutenir, in vitro, une activité de « killing » vis-à-vis de S. aureus et C. albicans ni pour protéger le patient des infections sévères et récidivantes

Sistema de manutenção preditiva aplicado a compressores radiais industriais utilizando análise de vibração

No mercado competitivo de hoje, os custos de produção, o prazo de entrega e a eficiência da máquina são valores cruciais para as empresas. Diante disso, se faz necessário a utilização de técnicas de manutenção que sejam capazes de identificar com antecedência os defeitos, evitando assim as paradas inoportunas e desnecessárias dos equipamentos. Logo, este trabalho tem como objetivo a implementação de um sistema de manutenção preditiva, aplicado a compressores radiais, utilizando técnicas de análise de vibração no diagnóstico de falhas mecânicas, auxiliando assim, no planejamento e controle da manutenção do equipamento. Com o propósito de extrair aos valores de vibração do equipamento monitorado, foram instalados acelerômetros microeletromecânicos (MEMs) MPU 9250 e fixados em locais próximos aos rolamentos do compressor. O processamento dos dados, implementação dos algoritmos matemáticos utilizados na análise de vibração e a interface entre os acelerômetros e o sistema de monitoramento, é feito através do microcomputador Raspberry Pi 3 B. Foram inseridas alterações insipientes e falhas que poderiam comprometer o funcionamento do equipamento e através das simulações de falhas foi possível extrair os dados relacionados as condições reais do equipamento e avaliar o comportamento do sistema em caso de falha no compressor. O acompanhamento do equipamento é feito através do sistema integrado de monitoramento Zandei (SIMZ), onde foram determinados parâmetros de referência, com valores limites, e quando estes valores são ultrapassados, o sistema envia mensagens para o setor de manutenção, indicando que o equipamento está apresentando algum defeito. Desta forma, o sistema pode ser utilizado como uma ferramenta de auxílio na gestão do setor de manutenção, proporcionando uma programação mais adequada de manutenção na empresa. [resumo fornecido pelo autor]In today's competitive market, production costs, lead times and machine efficiency are crucial values for companies. Therefore, it is necessary to use maintenance techniques that are able to identify defects in advance, thus avoiding untimely and unnecessary equipment stops. Therefore, this work aims to implement a predictive maintenance system, applied to radial compressors, using vibration analysis techniques in the diagnosis of mechanical failures, thus helping in the planning and control of equipment maintenance. In order to extract the vibration values of the monitored equipment, microelectromechanical accelerometers (MEMs) MPU 9250 were installed and fixed in places close to the compressor bearings. The data processing, implementation of the mathematical algorithms used in the vibration analysis and the interface between the accelerometers and the monitoring system, is done through the Raspberry Pi 3 B microcomputer. Insipient changes and failures that could compromise the equipment's operation and through the simulations of failures it was possible to extract the data related to the real conditions of the equipment and to evaluate the behavior of the system in case of compressor failure. The monitoring of the equipment is done through the integrated monitoring system Zandei (SIMZ), where reference parameters were determined, with limit values, and when these values are exceeded, the system sends messages to the maintenance sector, indicating that the equipment is showing any defect. In this way, the system can be used as an aid tool in the management of the maintenance sector, providing a more adequate maintenance schedule in the company. [resumo fornecido pelo autor