Corneal minimal visible lesion thresholds for 2.0 microm laser radiation

To support refinement of the ANSI Maximum Permissible Exposure safety limits, a series of experiments were conducted in vivo on Dutch Belted rabbit corneas to determine corneal minimum visible lesion thresholds for 2.0 microm continuous-wave laser irradiation. Single pulse radiant exposures were made at specified pulse durations of 0.1, 0.25, 0.5, 1.0, 2.0, and 4.0 s for spot 1/e(2) diameters of 1.17 mm and 4.02 mm. Threshold lesions were defined as the presence of a superficial surface whitening one hour after irradiation. Temperature measurements indicated that threshold peak temperatures were dependent on spot size and exposure duration. The exposure duration dependence of threshold average radiant exposure was described by an empirical power law equation: threshold radiant exposure[J/cm(2)]=a x exposure duration[s](b).     

Mixed-species biofilms in the food industry: Current knowledge and novel control strategies

Abstract

Attachment of microorganisms to food contact surfaces and the subsequent formation of biofilms may cause equipment damage, food spoilage and even diseases. Mixed-species biofilms are ubiquitous in the food industry and they generally exhibit higher resistance to disinfectants and antimicrobials compared to single-species biofilms. The physiology and metabolic activity of microorganisms in mixed-species biofilms are however rather complicated to study, and despite targeted research efforts, the potential role of mixed-species biofilms in food industry is still rather unexplored. In this review, we summarize recent studies in the context of bacterial social interactions in mixed-species biofilms, resistance to disinfectants, detection methods, and potential novel strategies to control the formation of mixed-species biofilms for enhanced food safety and food quality.     

Hybrid vortex simulations of wind turbines using a three‐dimensional viscous–inviscid panel method

A hybrid filament‐mesh vortex method is proposed and validated to predict the aerodynamic performance of wind turbine rotors and to simulate the resulting wake. Its novelty consists of using a hybrid method to accurately simulate the wake downstream of the wind turbine while reducing the computational time used by the method. The proposed method uses a hybrid approach, where the near wake is resolved by using vortex filaments, which carry the vorticity shed by the trailing edge of the blades. The interaction of the vortex filaments in the near vicinity of the wind turbine is evaluated using a direct calculation, whereas the contribution from the large downstream wake is calculated using a mesh‐based method. The hybrid method is first validated in detail against the well‐known MEXICO experiment, using the direct filament method as a comparison. The second part of the validation includes a study of the influence of the time‐integration scheme used for evolving the wake in time, aeroelastic simulations of the National Renewable Energy Laboratory 5 MW wind turbine and an analysis of the central processing unit time showing the gains of using the hybrid filament‐mesh method. Copyright © 2017 John Wiley & Sons, Ltd.     

A Euclidean color space in high agreement with the CIE94 color difference formula

Many consider it futile to try to create color spaces that are significantly more uniform than the CIELAB space, and, therefore, efforts concentrate on developing estimates of perceived color differences based on non‐Euclidean distances for this color space. A Euclidean color space is presented here, which is derived from the CIELAB by means of a simple adjustment of the a* and b* axes, and in which small Euclidean distances agree to within 10.5% with the non‐Euclidean distances given by the CIE94 formula. © 2000 John Wiley & Sons, Inc. Col Res Appl, 25, 64–65, 2000     

Growth and surface characterization of magnetron sputtered zinc nitride thin films

Zinc nitride films were deposited on Si(100) substrates at room temperature using RF-magnetron sputtering in pure N₂ and in Ar + N₂ atmospheres. Two active phonon modes (270.81 and 569.80 cm^− 1) are observed in Raman spectra for films deposited in Ar + N₂ atmosphere. Atomic force microscopy showed that the average surface roughness of the films deposited in pure N₂ atmosphere (1.3-3.33 nm) was less than for those deposited in a mixed Ar + N₂ atmosphere (10.3-12.8 nm). Low temperature cathodoluminescence showed two emission bands centered at 2.05 eV and 3.32 eV for both types of films.     

Tracking mesenchymal stem cells with iron oxide nanoparticle loaded poly(lactide-co-glycolide) microparticles

Monitoring the location, distribution and long-term engraftment of administered cells is critical for demonstrating the success of a cell therapy. Among available imaging-based cell tracking tools, magnetic resonance imaging (MRI) is advantageous due to its noninvasiveness, deep penetration, and high spatial resolution. While tracking cells in preclinical models via internalized MRI contrast agents (iron oxide nanoparticles, IO-NPs) is a widely used method, IO-NPs suffer from low iron content per particle, low uptake in nonphagocytotic cell types (e.g., mesenchymal stem cells, MSCs), weak negative contrast, and decreased MRI signal due to cell proliferation and cellular exocytosis. Herein, we demonstrate that internalization of IO-NP (10 nm) loaded biodegradable poly(lactide-co-glycolide) microparticles (IO/PLGA-MPs, 0.4-3 μm) in MSCs enhances MR parameters such as the r(2) relaxivity (5-fold), residence time inside the cells (3-fold) and R(2) signal (2-fold) compared to IO-NPs alone. Intriguingly, in vitro and in vivo experiments demonstrate that internalization of IO/PLGA-MPs in MSCs does not compromise inherent cell properties such as viability, proliferation, migration and their ability to home to sites of inflammation.     

Observation of breathing-like modes in an individual multiwalled carbon nanotube

We study collective vibrational breathing modes in the Raman spectrum of a multiwalled carbon nanotube. In correlation with high-resolution transmission electron microscopy, we find that these modes have energies differing by more than 23% from the radial breathing modes of the corresponding single-walled nanotubes. This shift in energy is explained with intershell interactions using a model of coupled harmonic oscillators. The strength of this interaction is related to the coupling strength expected for few-layer graphene.     

Herd-level risk factors associated with cow mortality in Swedish dairy herds

An increase in on-farm mortality (euthanasia and death) in dairy herds has been reported in several countries in the last decade. This does not only imply possible problems with animal welfare, but it also causes economic losses to the farmer. The objective of this study was to evaluate time trends in on-farm dairy cow mortality in Sweden and identify potential herd-level risk factors. Data were retrieved on all Swedish dairy herds enrolled in the milk recording scheme between 2002 and 2010. Herds with a herd size of <20 cows or a mortality rate (MR) of >40 dead or euthanized cows per 100 cow-years were excluded. Two different models were used: 1 multiple-year analysis, which included 6,898 herds during the period 2002 to 2010 and 1 single-year analysis including 4,252 herds for the year 2010, where other variables that were not present during the entire multiple year study were analyzed. The outcome variable was the number of euthanized and dead cows per year and season. A negative binomial regression model, adjusted for clustering within herd, was applied to both models. Fixed effects in the multiple-year analysis were breed, calving interval, herd size, milk yield, region, season, pasture period, and year. The fixed effects in the single-year analysis were breed, calving interval, conventional versus organic farming, herd size, housing system, milk yield, region, and season. The results demonstrated that MR gradually increased from 5.1 to 6.6 events per 100 cow-years during the study period. Swedish MR are consequently on par with, or even greater than, MR among dairy herds in other comparable countries. Higher mortality was associated with larger herd size, longer calving intervals, and herds that had Swedish Holstein as the predominant breed. Lower mortality was observed in herds with a higher herd average milk yield, during the fall and winter, and in organically managed herds. There were regional differences in mortality. An interaction between herd size and season was found in both models. Also, an interaction between housing system and milk yield was found in the single-year analysis. This first assessment of on-farm mortality in Swedish dairy herds confirmed that the MR has increased over the last few years. The study also identified some herd-level risk factors.     

Genome-wide association study using high-density single nucleotide polymorphism arrays and whole-genome sequences for clinical mastitis traits in dairy cattle

Mastitis is a mammary disease that frequently affects dairy cattle. Despite considerable research on the development of effective prevention and treatment strategies, mastitis continues to be a significant issue in bovine veterinary medicine. To identify major genes that affect mastitis in dairy cattle, 6 chromosomal regions on Bos taurus autosome (BTA) 6, 13, 16, 19, and 20 were selected from a genome scan for 9 mastitis phenotypes using imputed high-density single nucleotide polymorphism arrays. Association analyses using sequence-level variants for the 6 targeted regions were carried out to map causal variants using whole-genome sequence data from 3 breeds. The quantitative trait loci (QTL) discovery population comprised 4,992 progeny-tested Holstein bulls, and QTL were confirmed in 4,442 Nordic Red and 1,126 Jersey cattle. The targeted regions were imputed to the sequence level. The highest association signal for clinical mastitis was observed on BTA 6 at 88.97 Mb in Holstein cattle and was confirmed in Nordic Red cattle. The peak association region on BTA 6 contained 2 genes: vitamin D-binding protein precursor (GC) and neuropeptide FF receptor 2 (NPFFR2), which, based on known biological functions, are good candidates for affecting mastitis. However, strong linkage disequilibrium in this region prevented conclusive determination of the causal gene. A different QTL on BTA 6 located at 88.32 Mb in Holstein cattle affected mastitis. In addition, QTL on BTA 13 and 19 were confirmed to segregate in Nordic Red cattle and QTL on BTA 16 and 20 were confirmed in Jersey cattle. Although several candidate genes were identified in these targeted regions, it was not possible to identify a gene or polymorphism as the causal factor for any of these regions.