Chlorination is commonly used to control levels of bacteria in drinking water; however, viable bacteria may remain due to chlorine resistance. What is concerning is that surviving bacteria, due to ...co-selection factors, may also have increased resistance to common antibiotics. This would pose a public health risk as it could link resistant bacteria in the natural environment to human population. Here, we investigated the relationship between chlorine- and antibiotic-resistances by harvesting 148 surviving bacteria from chlorinated drinking-water systems and compared their susceptibilities against chlorine disinfectants and antibiotics. Twenty-two genera were isolated, including members of Paenibacillus, Burkholderia, Escherichia, Sphingomonas and Dermacoccus species. Weak (but significant) correlations were found between chlorine-tolerance and minimum inhibitory concentrations against the antibiotics tetracycline, sulfamethoxazole and amoxicillin, but not against ciprofloxacin; this suggest that chlorine-tolerant bacteria are more likely to also be antibiotic resistant. Further, antibiotic-resistant bacteria survived longer than antibiotic-sensitive organisms when exposed to free chlorine in a contact-time assay; however, there were little differences in susceptibility when exposed to monochloramine. Irrespective of antibiotic-resistance, spore-forming bacteria had higher tolerance against disinfection compounds. The presence of chlorine-resistant bacteria surviving in drinking-water systems may carry additional risk of antibiotic resistance.
•Twenty two genera were isolated from chlorinated drinking-water with a range of susceptibilities to chlorine and antibiotics.•Chlorine-resistant bacteria had higher MICs for tetracycline, sulfamethoxazole and amoxicillin.•In the presence of free chlorine, antibiotic-sensitive bacteria survival was less than antibiotic-resistant bacteria.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Measurements with different techniques point to a strong affinity of hydroxide ions for interfaces between water and hydrophobes, but some spectroscopic experiments do not detect excess hydroxide at ...the interface, while others do. Hydroxide ions are unusual in that they reduce the relative permittivity of an electrolyte solution more than other monovalent, monatomic ions. This implies that they suppress the collective dipole-moment fluctuations of nearby waters. We show that the absence of these fluctuations leads to a Hamaker-like force on the hydroxide ion that attracts it to regions where dipole-moment fluctuations are smaller than in bulk water, in other words, to regions of low relative permittivity. We show also that there is no contradiction between the picture of the basic, negatively charged interface and spectroscopic measurements. This is, in part, because the hydroxides are mostly below the outermost molecular layers. By combining a simple model for this fluctuation force with a modified Poisson-Boltzmann equation, we reproduce the dependence of the zeta-potential on pH, including the low isoelectric point, the approximate magnitude of the experimental surface charge density, and the Jones-Ray data for the dependence of surface tension on electrolyte concentration. We discuss also the apparent contradiction between molecular-dynamics simulations that deny and experiments that support a basic, negatively charged interface.
Despite claims, based largely on molecular dynamics simulations, that the surface of water at the air/water interface is acidic, with a positive charge, there is compelling experimental evidence that ...it is in fact basic, with a negative charge due to the specific adsorption of hydroxide ions. The oil/water interface behaves similarly. The pH dependence of the zeta potentials of oil drops has been measured by two very different techniques: on a single drop in a rotating electrophoresis cell and on about 1014 submicrometer drops in a 2 vol % emulsion by an electroacoustic method to give similar results with a sigmoidal pH dependence characterized by an isoelectric point at pH 2−3 and a half adsorption point about pH 5.5, or at 10−8.5 M hydroxide ion. This indicates that hydroxide ion is absorbed much more strongly than other anions. The pH dependence of a single N2 bubble has also been measured and has the same pH dependence, independently of whether HCl or HI is used to adjust the pH. These similarities between the pH dependences of the zeta potentials of air bubbles and oil drops, as well as those reported from streaming potentials on solid inert surfaces such as Teflon, indicate that water behaves similarly, with only subtle differences, at each of these low dielectric hydrophobic surfaces, with an isoelectric point of pH 2−4. In acidic solutions at pH’s below the isoelectric point, the surface is indeed positive, consistent with spectroscopic observations of the adsorption of hydrogen ions.
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IJS, KILJ, NUK, PNG, UL, UM
Stable oil‐in‐water emulsions are obtained in alkaline solution in the absence of any conventional surfactant. The oil droplets are charged by hydroxide ions (see picture). The surface charge density ...is obtained by measuring the size of the emulsion droplets by electroacoustics and the quantity of NaOH required to keep the pH constant during homogenization.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A synthesis of the literature provides an explanation for the hitherto unexplained charge on hydrophobic microfluidic substrates. It is due to the adsorption of hydroxide ions created by the enhanced ...autolysis of water at these surfaces.
Johne's disease (JD) control is often based on the culling of positive animals and the adoption of management practices that minimize exposure of calves to the pathogen Mycobacterium avium ssp. ...paratuberculosis (MAP). From 2010 to 2013, Ontario, Canada, instituted a voluntary Johne's control program consisting of whole-herd testing and a Risk Assessment and Management Plan (RAMP). The RAMP consisted of 38 questions that evaluated 5 different management areas to characterize herd risk for MAP introduction and within-herd spread. The RAMP produced a numerical score for each area, with higher scores associated with higher risk. The RAMP focused on animal purchases, calving management, calf management, and heifer and cow cleanliness and management. In the summer of 2019, the RAMP was repeated on 180 farms that had participated in the JD program of 2010 to 2013 and had bulk tank milk ELISA results from 2013 and 2017. This cross-sectional study demonstrated that many producers changed management practices over the 4- to 7-year period. Producers changed their cattle buying practices, with a reduction in purchasing from multiple sources and more herds refraining from buying in animals. However, overall scores were higher in 2019 than in 2013. The 2019 RAMP indicated that fewer farms were utilizing individual calving pens in 2019 than in 2013 (13% vs. 26%), yet more farms had policies in place to deal with sick or suspect JD cows entering the maternity area (92% vs. 74%). Management changes occurred over time, some of which represent increased risk (crowded maternity pens) and others decreased risk (closed herd, protocols in place for JD-positive cows) for MAP introduction and transmission. These results highlight the importance of frequent risk assessments and the documentation of changes to management practices on-farm as a means to assess herd disease risk more accurately.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The objectives of this study were (1) to describe navel healing in male and female neonatal Holstein calves over a 14-d observation period, and (2) to determine the associations of dam parity, ...calving factors, and calf factors with navel measurements and time to healing. A total of 68 Holstein calves (43 female and 25 male) were enrolled. Navel healing outcomes (cessation of navel discharge, navel cord remnant drying, navel cord remnant drop-off) and navel stump measurement outcomes (proximal diameter, distal diameter, length) were recorded every 24 ± 1 h for a 14-d observation period. Data were also collected for dam parity, calving factors (time of birth, calving ease), and calf factors (calf sex, calf vitality at birth, birth weight, average daily gain, serum total protein, and medical treatment or treatments). The mean time to navel cord remnant drying was 2 d, and all calves had dry navels by d 5. A total of 56% of calves retained their navel cord remnant beyond the end of the observation period, and calves began to shed their navel cord remnants as early as d 2. In addition, at least once during the observation period, 85% of calves had a proximal navel diameter measurement over a 13-mm threshold recently proposed to identify navel infections. For distal navel diameter measurements, 72% of calves had a diameter over the 13-mm threshold at least once during the observation period. No associations were identified between navel healing outcomes and dam, calving, and calf factors. Navel measurement outcomes were associated with calving and calf factors. Specifically, proximal navel stump diameter was associated with the day of observation (decreased from d 5 to 14), calf sex (smaller in female calves), time of birth (larger in calves born overnight or unobserved, compared with the morning), and birth weight (larger in birth weights >44.1 kg compared with <38.5 kg). Distal navel stump diameter was associated with calf sex, medical treatment, and day of observation; however, we observed an interaction between sex and day of observation (larger in male calves on d 3 to 7, d 9, and d 12, compared with female calves), and sex and medical treatment (larger in untreated male calves, no difference between treated male and female calves). Navel stump length was associated with time of birth (longer in calves born overnight or unobserved compared with any other time) and the interaction of birth weight and day of observation (longer in birth weights >44.1 kg compared with 38.6–41.5 kg on d 3, 8–10, and 13, and 41.6–44.0 kg on d 3, 5, 7–8, and 13). The wide range in time to navel cord remnant drying and drop-off suggest that these measures may not be adequate indicators of calf age on their own. More research on navel healing is required to improve our understanding of factors that influence navel measurements and time to healing, as well as how this information could be used in an objective assessment of navel health.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Very energetic astrophysical events are required to accelerate cosmic rays to above 10(18) electronvolts. GRBs (γ-ray bursts) have been proposed as possible candidate sources. In the GRB 'fireball' ...model, cosmic-ray acceleration should be accompanied by neutrinos produced in the decay of charged pions created in interactions between the high-energy cosmic-ray protons and γ-rays. Previous searches for such neutrinos found none, but the constraints were weak because the sensitivity was at best approximately equal to the predicted flux. Here we report an upper limit on the flux of energetic neutrinos associated with GRBs that is at least a factor of 3.7 below the predictions. This implies either that GRBs are not the only sources of cosmic rays with energies exceeding 10(18) electronvolts or that the efficiency of neutrino production is much lower than has been predicted.
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DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The effect of fatty acid impurities on the electrophoretic mobility of hexadecane in water emulsions is reinterpreted, occasioned by an error in the surface charge attributed to the fatty acids. The ...results are consistent with a surface charge contributed by both hydroxide ions and deprotonated fatty acids (see picture).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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