Antibacterial action of dental cements: An in vitro study

The antibacterial activity of seven commercialy available dental cements (Eugespad®, Dentical®, Dycal®, Expaliner®, PR. Scell®, PR. Base Cement®, PR. Lining Cement®) against 1) bacterial species implicated in carious lesions or in dental plaque (Actinomyces israelii ATCC 10048, Actinomyces viscosus ATCC 19246, Streptococcus mutans ATCC 25175, Streptococcus sanguis ATCC 10557) and 2) bacterial samples of stimulated saliva was studied, in vitro, using a modification of the method of McComb and Ericson (1987).Dycal® and Expaliner® did not affect bacteria whereas the other dental cements displayed some antibacterial properties. Eugespad® was the most active followed by PR. Base Cement® + PR. Scell® + Dentical® and by PR. Lining Cement®.Associated with mechanical and biocompatibility properties, these differences could be taken into account when choosing a dental cement for clinical use.Le but de ce travail a été de comparer, in vitro, les éventuelles propriétés antibactériennes de différents ciments: 1 ciment ZOE (Eugespad®), 2 ciments à base d’hydroxyde de calcium (Dentical®, Dycal®), 3 ciments verre-ionomère (PR. glass ionomer LC®, PR. glass ionomer BC®, PR. Scell® glass ionomer) et un ciment adhésif (Expaliner®).Ces matériaux ont été testés vis-à-vis d’espèces bactériennes retrouvées dans la carie dentaire ou dans la plaque dentaire (Actinomyces viscosus ATCC 19246, Actinomyces israelii ATCC 10048, Streptococcus mutans ATCC 25175, Streptococcus sanguis ATCC 10557) et des échantillons de salive totale.L’activité antibactérienne a été appréciée par une méthode d’inhibition de croissance en milieu solide dérivée de la technique des antibiogrammes (McComb, 1987). Chaque ciment, préparé selon les recommandations des fabricants, était déposé au fond d’un puits creusé dans une gélose (milieu de Schaedler enrichi avec du sang de mouton) ensemencée avec une préculture de 48 heures de l’une des souches bactériennes retenues. Après incubation à l’étuve à 37°C en anaérobiose, les diamètres des zones d’inhibition de croissance étaient mesurés au temps t = 48 heures. Pour chaque espèce et matériau testés, l’expérimentation a été répétée 10 fois.Parmi les sept matériaux testés, le Dycal® et l’Expaliner® n’ont entraîné aucune zone d’inhibition de croissance. Les plus fortes zones d’inhibition ont été obtenues avec le ciment ZOE. L’activité des quatre autres ciments a varié en fonction de la nature du ciment et de l’espèce bactérienne.Ces modifications d’activité pourraient, après confirmation de ces premiers résultats, être prises en compte dans le choix clinique d’un ciment dentaire

Mesure du hiatus dent-matériau de restauration: Intérêt du MEB

The purpose of this article was to describe a method of measuring the interface between cavity walls and restorative materials and to evaluate it by comparing the interface of amalgam, composite restorations and cavity walls. With the different restorative materials the interface could be measured. Its value was dependent of the type of restoration. This methodology is available for ail restorative biomaterials. It could be of interest in clinical evaluation of restorative materials.Cet article décrit une méthode de mesure du hiatus dent-matériau de reconstitution dentaire. Cette méthode a été évaluée en comparant les valeurs moyennes du hiatus au niveau de restaurations au composite et à l’amalgame. Quel que soit le matériau employé, un hiatus a pu être mis en évidence et mesuré. La valeur de cet hiatus dépend de la nature du matériau de restauration et varie en fonction du temps. Cette méthode, applicable à tous les matériaux d’obturation, pourrait représenter un critère supplémentaire dans l’évaluation d’un matériau d’obturation

All-sky search for short gravitational-wave bursts in the second Advanced LIGO and Advanced Virgo run

We present the results of a search for short-duration gravitational-wave transients in the data from the second observing run of Advanced LIGO and Advanced Virgo. We search for gravitational-wave transients with a duration of milliseconds to approximately one second in the 32-4096 Hz frequency band with minimal assumptions about the signal properties, thus targeting a wide variety of sources. We also perform a matched-filter search for gravitational-wave transients from cosmic string cusps for which the waveform is well modeled. The unmodeled search detected gravitational waves from several binary black hole mergers which have been identified by previous analyses. No other significant events have been found by either the unmodeled search or the cosmic string search. We thus present the search sensitivities for a variety of signal waveforms and report upper limits on the source rate density as a function of the characteristic frequency of the signal. These upper limits are a factor of 3 lower than the first observing run, with a 50% detection probability for gravitational-wave emissions with energies of ∼10-9 Mc2 at 153 Hz. For the search dedicated to cosmic string cusps we consider several loop distribution models, and present updated constraints from the same search done in the first observing run

Search for Eccentric Binary Black Hole Mergers with Advanced LIGO and Advanced Virgo during Their First and Second Observing Runs

When formed through dynamical interactions, stellar-mass binary black holes (BBHs) may retain eccentric orbits (e > 0.1 at 10 Hz) detectable by ground-based gravitational-wave detectors. Eccentricity can therefore be used to differentiate dynamically formed binaries from isolated BBH mergers. Current template-based gravitational-wave searches do not use waveform models associated with eccentric orbits, rendering the search less efficient for eccentric binary systems. Here we present the results of a search for BBH mergers that inspiral in eccentric orbits using data from the first and second observing runs (O1 and O2) of Advanced LIGO and Advanced Virgo. We carried out the search with the coherent WaveBurst algorithm, which uses minimal assumptions on the signal morphology and does not rely on binary waveform templates. We show that it is sensitive to binary mergers with a detection range that is weakly dependent on eccentricity for all bound systems. Our search did not identify any new binary merger candidates. We interpret these results in light of eccentric binary formation models. We rule out formation channels with rates ⪆100 Gpc-3 yr-1 for e > 0.1, assuming a black hole mass spectrum with a power-law index ≲2

Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model

We present results from a semicoherent search for continuous gravitational waves from the low-mass X-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the $\mathcal{J}$-statistic, and by analysing data from Advanced LIGO's second observing run. In the frequency range searched, from $60$ to $650\,\mathrm{Hz}$, we find no evidence of gravitational radiation. At $194.6\,\mathrm{Hz}$, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95\% confidence) of $h_0^{95\%} = 3.47 \times 10^{-25}$ when marginalising over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering

Search for intermediate mass black hole binaries in the first and second observing runs of the Advanced LIGO and Virgo network

Gravitational-wave astronomy has been firmly established with the detection of gravitational waves from the merger of ten stellar-mass binary black holes and a neutron star binary. This paper reports on the all-sky search for gravitational waves from intermediate mass black hole binaries in the first and second observing runs of the Advanced LIGO and Virgo network. The search uses three independent algorithms: two based on matched filtering of the data with waveform templates of gravitational-wave signals from compact binaries, and a third, model-independent algorithm that employs no signal model for the incoming signal. No intermediate mass black hole binary event is detected in this search. Consequently, we place upper limits on the merger rate density for a family of intermediate mass black hole binaries. In particular, we choose sources with total masses M=m1+m2ϵ[120,800] M and mass ratios q=m2/m1ϵ[0.1,1.0]. For the first time, this calculation is done using numerical relativity waveforms (which include higher modes) as models of the real emitted signal. We place a most stringent upper limit of 0.20 Gpc-3 yr-1 (in comoving units at the 90% confidence level) for equal-mass binaries with individual masses m1,2=100 M and dimensionless spins χ1,2=0.8 aligned with the orbital angular momentum of the binary. This improves by a factor of ∼5 that reported after Advanced LIGO's first observing run

A Cryogenic Silicon Interferometer for Gravitational-wave Detection

The detection of gravitational waves from compact binary mergers by LIGO has opened the era of gravitational wave astronomy, revealing a previously hidden side of the cosmos. To maximize the reach of the existing LIGO observatory facilities, we have designed a new instrument that will have 5 times the range of Advanced LIGO, or greater than 100 times the event rate. Observations with this new instrument will make possible dramatic steps toward understanding the physics of the nearby universe, as well as observing the universe out to cosmological distances by the detection of binary black hole coalescences. This article presents the instrument design and a quantitative analysis of the anticipated noise floor

Dryland Malt Barley Yield and Quality Affected by Tillage, Cropping Sequence, and Nitrogen Fertilization

Malt barley (Hordeum vulgare L.) yield and quality have been evaluated using various cultivars and N rates but little is known about the effects of tillage and cropping sequence. We evaluated the effects of tillage, cropping sequence, and N fertilization on dryland malt barley yield, grain characteristics, N uptake, and N use-efficiency from 2006 to 2011 in eastern Montana. Treatments were no-till continuous malt barley (NTCB), no-till malt barley–pea (Pisum sativum L.) (NTB–P), no-till malt barley–fallow (NTB–F), and conventional till malt barley–fallow (CTB–F), with split application of N rates (0,40, 80, and 120 kg N ha–1) in randomized complete block with three replications. As N rates increased, malt barley grain yield, protein concentration, and N uptake increased in NTB–F, NTB–P, and NTCB, but test weight, plumpness, and N-use efficiency decreased in all tillage and cropping sequence treatments. Similarly, plant stand, biomass (stems and leaves) yield, and N uptake increased with increased N rates. Grain and biomass yields, N uptake, and N-use efficiency were greater in CTB–F than in NTB–P and NTCB but tillage had no effect on these parameters. Malt barley yield and N uptake varied with cropping sequences and N rates among years. Although grain yield increased with increased N rates, NTB–P with N rates between 40 and 80 kg N ha−1 may be used to sustain dryland malt barley yield and quality (protein concentration \u3c 135 g kg−1, plumpness \u3e 800 g kg−1), thereby helping to reduce the potentials for soil erosion and N leaching and increase soil organic matter in the northern Great Plains