18 research outputs found

    Micro- and Nanotopography Sensitive Bacterial Attachment Mechanisms: A Review

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    Bacterial attachment to material surfaces can lead to the development of biofilms that cause severe economic and health problems. The outcome of bacterial attachment is determined by a combination of bacterial sensing of material surfaces by the cell and the physicochemical factors in the near-surface environment. This paper offers a systematic review of the effects of surface topography on a range of antifouling mechanisms, with a focus on how topographical scale, from micro- to nanoscale, may influence bacterial sensing of and attachment to material surfaces. A good understanding of these mechanisms can facilitate the development of antifouling surfaces based on surface topography, with applications in various sectors of human life and activity including healthcare, food, and water treatment

    Supplement: "Localization and broadband follow-up of the gravitational-wave transient GW150914" (2016, ApJL, 826, L13)

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    This Supplement provides supporting material for Abbott et al. (2016a). We briefly summarize past electromagnetic (EM) follow-up efforts as well as the organization and policy of the current EM follow-up program. We compare the four probability sky maps produced for the gravitational-wave transient GW150914, and provide additional details of the EM follow-up observations that were performed in the different bands

    Observation of gravitational waves from the coalescence of a 2.5−4.5 M⊙ compact object and a neutron star

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    Search for gravitational-lensing signatures in the full third observing run of the LIGO-Virgo network

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    Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects

    Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

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    Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level

    Ultralight vector dark matter search using data from the KAGRA O3GK run

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    Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

    Blue 405 nm LED light effectively inactivates bacterial pathogens on substrates and packaging materials used in food processing

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    Abstract This study investigates the antimicrobial effectiveness of 405 nm light emitting diodes (LEDs) against pathogenic Escherichia coli O157:H7, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella Typhimurium, and Staphylococcus aureus, in thin liquid films (TLF) and on solid surfaces. Stainless steel (SS), high density polyethylene (HDPE), low density polyethylene (LDPE), and borosilicate glass were used as materials typically encountered in food processing, food service, and clinical environments. Anodic aluminum oxide (AAO) coupons with nanoscale topography were used, to evaluate the effect of topography on inactivation. The impact of surface roughness, hydrophobicity, and reflectivity on inactivation was assessed. A 48 h exposure to 405 nm led to reductions ranging from 1.3 (E. coli) to 5.7 (S. aureus) log CFU in TLF and 3.1 to 6.3 log CFU on different solid contact surfaces and packaging materials. All inactivation curves were nonlinear and followed Weibull kinetics, with better inactivation predictions on surfaces (0.89 ≤ R 2 ≤ 1.0) compared to TLF (0.76 ≤ R 2 ≤ 0.99). The fastest inactivation rate was observed on small nanopore AAO coupons inoculated with L. monocytogenes and S. aureus, indicating inactivation enhancing potential of these surfaces. These results demonstrate significant promise of 405 nm LEDs for antimicrobial applications in food processing and handling and the healthcare industry

    Time after apple pressing and insoluble solids influence the efficiency of the UV treatment of cloudy apple juice

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    The effects of suspended insoluble solids (SIS) concentration and particle size, and the time after apple pressing on the efficiency of UV treatment of cloudy apple juice were evaluated. Clear model solutions (formulated to resemble physicochemical characteristics of apple juice) and commercial apple juice, containing different solids concentrations, were treated using a CiderSure reactor at 14 mJ cm−2 UV dose. Particle size effect was assessed on model solutions treated at 7 mJ cm−2 UV dose. The juice flow rate through the UV machine was determined. All samples were inoculated with Escherichia coli ATCC 25922 (106–107 CFU ml−1) and UV treated at 214.5 ml s−1 fixed flow rate. Log reductions were calculated. Increasing SIS concentrations did not significantly affect the juice flow rate (P > 0.05) but adversely affected the inactivation of E. coli (P < 0.05). For solutions treated at 7 mJ cm−2, a negative linear relationship between SIS and flow rate was observed and particle size significantly affected the flow rate (P < 0.05). A negative effect of time after apple pressing on the juice flow rate was observed and this effect was apple cultivar-dependent, thus UV efficiency would be improved if time after pressing is minimized.United States Department of Agriculture/[2010-51110-21511]/USDA/Estados UnidosNational Institute of Food and Agriculture/[2010-51110-21511]/NIFA/Estados UnidosFulbright International Exchange Program/[]//Estados UnidosCornell University/[]//Estados UnidosUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro Nacional de Ciencia y Tecnología de Alimentos (CITA

    Ascorbic acid and selected preservatives influence effectiveness of UV treatment of apple juice

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    The influence of ascorbic acid, sodium benzoate, potassium sorbate, and sulfur dioxide on the effectiveness of UV pasteurization of apple juice and the effect of UV exposure on the stability of these compounds were evaluated. The concentration of ascorbic acid, total vitamin C, benzoate, sorbate, and sulfur dioxide, and the juices' physicochemical properties were determined. UV treatment consisted of multiple passes at a fixed dose of 14 mJ cm−2 per pass, achieved by adjusting the juice flow rate through the UV machine. Samples containing ascorbic acid were inoculated with Escherichia coli ATCC 25922 (107 CFU ml−1) and analyzed for microbial reduction due to UV. The addition of ascorbic acid, sorbate, and benzoate significantly increased juices' absorption coefficients, which caused a reduction in the juice flow rate (p 0.05) but decreased sulfur dioxide, ascorbic acid, and particularly sorbate levels (p < 0.05). Increases in ascorbic acid concentration decreased inactivation of E. coli (p < 0.0001). Thus, additives than can either adversely influence UV efficiency or be degraded due to UV exposure should be added after UV treatment.National Integrated Food Safety Initiative/[2010-01394]/NIFSI-USDA/Estados UnidosCornell University/[]//Estados UnidosUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro Nacional de Ciencia y Tecnología de Alimentos (CITA
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