1,375 research outputs found
Quantitative Real-time PCR (qPCR) for the Determination of Salmonella Levels in Lairage
The sensitivity of the quantitative polymerase chain reaction assay (qPCR) was shown to be 10,000 Salmonella colony forming units (cfu) of bacteria per gram of fecal matter; this means that this rapid and specific test is a useful tool for the industry. The study found a trend toward a reduced, but not statistically significant, amount of Salmonella in lairage pens from standard hygiene practices of washing pens between groups of swine. This reduction of Salmonella in lairage pens may result in decrease transmission between groups, and, ultimately, in fewer numbers of contaminated carcasses at slaughter. It might also allow one to determine if on farm and transport methods are reducing Salmonella fecal incidence in lairage pens. The lack of significance is partially due to the low number of positive pens in this study before washing. Due to the low numbers found in pens in this study, samples were not collected from transport as they would have not lead to significant differences between various treatments
Translating solid state organic synthesis from a mixer mill to a continuous twin screw extruder
YesA study on the translation of a solid-state synthetic reaction from a mechanochemical mixer-mill to a continuous twin-screw extruder is discussed herein. The study highlights some considerations to be made and parameters to be tested in the context of a model fluorination reaction, which is the first organic fluorination to be attempted using extrusion. Upon optimization, which features the first use of grinding auxiliary solids to enable effective synthetic extrusion, the difluorination reaction was successfully translated to the extruder, leading to a 100-fold improvement in Space Time Yield (STY); 29 kg m−3 day−1 in a mixer mill to 3395 kg m−3 day−1 in a twin screw extruder.D. L. B is grateful to the EPSRC for a First Grant (D. L. B. EP/P002951/1), CRD for a studentship award to J. L. H., Queen’s University Belfast for a Visiting Research Fellowship and the School of Chemistry at Cardiff University for generous support. S. L. J. is grateful to EPSRC for support (EP/L019655/1)
Potentiometric Titration of Sulfate in Water and Soil Extracts Using a Lead-Mercury Amalgam Indicator Electrode
Sulfate concentrations in pure solutions, drainage waters,
and soil saturation extracts were determined potentiometrically
using a 70% Pb and 30% Hg amalgam indicator electrode and
a saturated calomel reference electrode. Adjusting all samples
to pH 4.7 allowed titration to a fixed potential on an automatic
titrator. Sulfate concentrations ranging from 0.2 to 10 mmole/
liter were determined by this method and compared with
concentration determined by a turbidimetric method. Results
from the two methods did not differ significantly, but the potentiometric
titration method was more precise, sensitive, and
rapid
Native electrospray mass spectrometry approaches to probe the interaction between zinc and an anti-angiogenic peptide from histidine-rich glycoprotein
This work was supported by the BBSRC (grant ref. BB/J006467/1 and CASE studentship to E.M.M.) and the British Heart Foundation (grant ref. PG/15/9/31270 and FS/15/42/31556).Zinc modulates the biological function of histidine-rich glycoprotein (HRG) through binding to its His-rich region (HRR). The Zn2+-binding properties of a 35 amino-acid biologically-active peptide mimic of the HRR, HRGP330, were investigated using dissociative mass spectrometry approaches in addition to travelling-wave ion mobility mass spectrometry (TWIM-MS). Native mass spectrometry confirmed zinc binding to HRGP330; however, broadening of the 1H NMR resonances upon addition of Zn2+ ions precluded the attainment of structural information. A complementary approach employing TWIM-MS indicated that HRGP330 has a more compact structure in the presence of Zn2+ ions. Top-down MS/MS data supported a metal-binding-induced conformational change, as fewer fragments were observed for Zn2+-bound HRGP330. Zn2+-bound fragments of both N-terminal and C-terminal ends of the peptide were identified from collision-induced dissociation (CID) and electron transfer dissociation/proton transfer reaction (ETD/PTR) experiments, suggesting that multiple binding sites exist within this region of HRG. The combination of mass spectrometry and NMR approaches provides new insight into the highly dynamic interaction between zinc and this His-rich peptide.Publisher PDFPeer reviewe
Absence of lattice strain anomalies at the electronic topological transition in zinc at high pressure
High pressure structural distortions of the hexagonal close packed (hcp)
element zinc have been a subject of controversy. Earlier experimental results
and theory showed a large anomaly in lattice strain with compression in zinc at
about 10 GPa which was explained theoretically by a change in Fermi surface
topology. Later hydrostatic experiments showed no such anomaly, resulting in a
discrepancy between theory and experiment. We have computed the compression and
lattice strain of hcp zinc over a wide range of compressions using the
linearized augmented plane wave (LAPW) method paying special attention to
k-point convergence. We find that the behavior of the lattice strain is
strongly dependent on k-point sampling, and with large k-point sets the
previously computed anomaly in lattice parameters under compression disappears,
in agreement with recent experiments.Comment: 9 pages, 6 figures, Phys. Rev. B (in press
Time‐lapse photogrammetry reveals hydrological controls of fine‐scale High‐Arctic glacier surface roughness evolution
In a warming Arctic, as glacier snowlines rise, short- to medium-term increases in seasonal bare-ice extent are forecast for the next few decades. These changes will enhance the importance of turbulent energy fluxes for surface ablation and glacier mass balance. Turbulent energy exchanges at the ice surface are conditioned by its topography, or roughness, which has been hypothesized to be controlled by supraglacial hydrology at the glacier scale. However, current understanding of the dynamics in surface topography, and the role of drainage development, remains incomplete, particularly for the transition between seasonal snow cover and well-developed, weathered bare-ice. Using time-lapse photogrammetry, we report a daily timeseries of fine (millimetre)-scale supraglacial topography at a 2 m2 plot on the Lower Foxfonna glacier, Svalbard, over two 9-day periods in 2011. We show traditional kernel-based morphometric descriptions of roughness were ineffective in describing temporal change, but indicated fine-scale albedo feedbacks at depths of ~60 mm contributed to conditioning surface topography. We found profile-based and two-dimensional estimates of roughness revealed temporal change, and the aerodynamic roughness parameter, z0, showed a 22–32% decrease from ~1 mm following the exposure of bare-ice, and a subsequent 72–77% increase. Using geostatistical techniques, we identified ‘hole effect’ properties in the surface elevation semivariograms, and demonstrated that hydrological drivers control the plot-scale topography: degradation of superimposed ice reduces roughness while the inception of braided rills initiates a subsequent development and amplification of topography. Our study presents an analytical framework for future studies that interrogate the coupling between ice surface roughness and hydro-meteorological variables and seek to improve parameterizations of topographically evolving bare-ice areas
Acute gastrointestinal illness in two Inuit communities : burden of illness in Rigolet and Iqaluit, Canada : author version
Results of this study highlight the need for systematic data collection to better understand and support previously anecdotal indications of high acute gastrointestinal illness (AGI) incidence. Cross-sectional retrospective surveys captured information on AGI and potential environmental risk factors. Lack of access to health services can result in reduced care-seeking behaviour, which can compromise the quality and quantity of available surveillance data. The aim of the research was to estimate the incidence and prevalence of AGI, and to identify potential socio-economic and environmental risk factors in the Inuit communities of Rigolet, Nunatsiavut and Iqaluit in Nunavut, Canada
Confined granular packings: structure, stress, and forces
The structure and stresses of static granular packs in cylindrical containers
are studied using large-scale discrete element molecular dynamics simulations
in three dimensions. We generate packings by both pouring and sedimentation and
examine how the final state depends on the method of construction. The vertical
stress becomes depth-independent for deep piles and we compare these stress
depth-profiles to the classical Janssen theory. The majority of the tangential
forces for particle-wall contacts are found to be close to the Coulomb failure
criterion, in agreement with the theory of Janssen, while particle-particle
contacts in the bulk are far from the Coulomb criterion. In addition, we show
that a linear hydrostatic-like region at the top of the packings unexplained by
the Janssen theory arises because most of the particle-wall tangential forces
in this region are far from the Coulomb yield criterion. The distributions of
particle-particle and particle-wall contact forces exhibit
exponential-like decay at large forces in agreement with previous studies.Comment: 11 pages, 11 figures, submitted to PRE (v2) added new references,
fixed typo
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