This work reviews the use of atomic force microscopy (AFM) as a tool to investigate oleogels of edible triglyceride oils. Specific attention is given to those oleogels based on phytosterols and their ...esters, a class of material the authors have studied extensively. This work consists of a summary of the role of AFM in imaging edible oleogels, including the processing and preparation steps required to obtain high-quality AFM images of them. Finally, there is a comparison between AFM and other techniques that may be used to obtain structural information from oleogel samples. The aim of this review is to provide a useful introduction and summary of the technique for researchers in the fields of gels and food sciences looking to perform AFM measurements on edible oleogels.
Contagious Ovine Digital Dermatitis (CODD) is an emerging and common infectious foot disease of sheep which causes severe welfare and economic problems for the sheep industry. The aetiology of the ...disease is not fully understood and control of the disease is problematic. The aim of this study was to investigate the polybacterial aetiopathogenesis of CODD and the effects of antibiotic treatment, in a longitudinal study of an experimentally induced disease outbreak using a 16S rRNA gene amplicon sequencing approach.
CODD was induced in 15/30 experimental sheep. During the development of CODD three distinct phenotypic lesion stages were observed. These were an initial interdigital dermatitis (ID) lesion, followed by a footrot (FR) lesion, then finally a CODD lesion. Distinct microbiota were observed for each lesion in terms of microbial diversity, clustering and composition. Porphyromonadaceae, Family XI, Veillonellaceae and Fusobacteriaceae were significantly associated with the diseased feet. Veillonellaceae and Fusobacteriaceae were most associated with the earlier stages of ID and footrot rather than CODD. Following antibiotic treatment of the sheep, the foot microbiota showed a strong tendency to return to the composition of the healthy state. The microbiota composition of CODD lesions collected by swab and biopsy methods were different. In particular, the Spirochaetaceae family were more abundant in samples collected by the biopsy method, suggesting that these bacteria are present in deeper tissues of the diseased foot.
In this study, CODD presented as part of a spectrum of poly-bacterial foot disease strongly associated with bacterial families Porphyromonadaceae, Family XI (a family in Clostridiales also known as Clostridium cluster XI), Veillonellaceae and Fusobacteriaceae which are predominately Gram-negative anaerobes. Following antibiotic treatment, the microbiome showed a strong tendency to return to the composition of the healthy state. The composition of the healthy foot microbiome does not influence susceptibility to CODD. Based on the data presented here and that CODD appears to be the severest end stage of sheep infectious foot disease lesions, better control of the initial ID and FR lesions would enable better control of CODD and enable better animal welfare.
The ChemCam instrument on the Mars Science Laboratory rover
Curiosity
will use laser-induced breakdown spectroscopy (LIBS) to analyze major and minor element chemistry from sub-millimeter spot sizes, ...at ranges of ∼1.5–7 m. To interpret the emission spectra obtained, ten calibration standards will be carried on the rover deck. Graphite, Ti metal, and four glasses of igneous composition provide primary, homogeneous calibration targets for the laser. Four granular ceramic targets have been added to provide compositions closer to soils and sedimentary materials like those expected at the Gale Crater field site on Mars. Components used in making these ceramics include basalt, evaporite, and phyllosilicate materials that approximate the chemical compositions of detrital and authigenic constituents of clastic and evaporite sediments, including the elevated sulfate contents present in many Mars sediments and soils. Powdered components were sintered at low temperature (800 °C) with a small amount (9 wt.%) of lithium tetraborate flux to produce ceramics that retain volatile sulfur yet are durable enough for the mission. The ceramic targets are more heterogeneous than the pure element and homogenous glass standards but they provide standards with compositions more similar to the sedimentary rocks that will be
Curiosity’s
prime targets at Gale Crater.
The Mars Science Laboratory rover, Curiosity, is equipped with ChemCam, a laser‐induced breakdown spectroscopy (LIBS) instrument, to determine the elemental composition of nearby targets quickly and ...remotely. We use a laboratory sample set including prepared mixtures of basalt with systematic variation in hydrated mineral content and compositionally well‐characterized, altered basaltic volcanic rocks to measure hydrogen by characterizing the H‐alpha emission line in LIBS spectra under Martian environmental conditions. The H contents of all samples were independently measured using thermogravimetric analysis. We found that H peak area increases with weight percent H for our laboratory mixtures with basaltic matrices. The increase is linear with weight percent H in the mixtures with structurally bound H up to about 1.25 wt.% H and then steepens for higher H‐content samples, a nonlinear trend not previously reported but potentially important for characterizing high water content materials. To compensate for instrument, environmental, and target matrix‐related effects on quantification of H content from the LIBS signal, we examined multiple normalization methods. The best performing methods utilize O 778‐ and C 248‐nm emission lines. The methods return comparable results when applied to ChemCam data of H‐bearing materials on Mars. The calibration and normalization methods tested here will aid in investigations of H by LIBS on Mars with ChemCam and SuperCam. Further laboratory work will aid quantification across different physical matrices and heterogeneous textures because of differences we observed in H in pelletized and natural rock samples of the same composition.
Plain Language Summary
ChemCam, one of the Curiosity rover instruments, measures the chemical composition of nearby targets quickly and remotely using laser‐induced breakdown spectroscopy (LIBS). The LIBS technique requires laboratory calibration to quantitatively determine the abundances of major and minor elements. We measured prepared mixtures of basalt with systematic variation in hydrated mineral content and compositionally well‐characterized, altered basaltic volcanic rocks with a ChemCam‐analog instrument under Martian environmental conditions to characterize LIBS hydrogen emission. To compensate for instrument, environmental, and target‐related effects on quantification of H content from the LIBS signal, we tested multiple normalization methods. While the H signal increased nonlinearly with weight percent for high H samples, we found laboratory calibrations that allowed us to successfully determine the H content of Martian veins and bedrock measured by ChemCam.
Key Points
Multiple calibration and normalization methods to determine hydrogen content from the hydrogen‐alpha LIBS emission line were evaluated
O 778‐ and C 248‐nm norms have the lowest scatter for the lab set, best correct for distance, and successfully determine H for Martian rocks
Nonlinear calibrations for high‐H samples and differences in H between rocks, when natural versus pelletized, warrant further study
Ancient environmental conditions on Mars can be probed through the identification of minerals on its surface, including water‐deposited salts and cements dispersed in the pore space of sedimentary ...rocks. Laser‐induced breakdown spectroscopy (LIBS) analyses by the Martian rover Curiosity's ChemCam instrument can indicate salts, and ChemCam surveys aid in identifying and selecting sites for further, detailed in situ analyses. We performed laboratory LIBS experiments under simulated Mars conditions with a ChemCam‐like instrument on a series of mixtures containing increasing concentrations of salt in a basaltic background to investigate the potential for identifying and quantifying chloride, carbonate, and sulfate salts found only in small amounts, dispersed in bulk rock with ChemCam, rather than concentrated in veins. Data indicate that the presence of emission lines from the basalt matrix limited the number of Cl, C, and S emission lines found to be useful for quantitative analysis; nevertheless, several lines with intensities sensitive to salt concentration were identified. Detection limits for the elements based on individual emission lines ranged from ~20 wt % carbonate (2 wt % C), ~5–30 wt % sulfate (1–8 wt % S), and ~5–10 wt % chloride (3–6 wt % Cl) depending on the basaltic matrix and/or salt cation. Absolute quantification of Cl, C, and S in the samples via univariate analysis depends on the cation‐anion pairing in the salt but appears relatively independent of matrices tested, following normalization. These results are promising for tracking relative changes in the salt content of bulk rock on the Martian surface with ChemCam.
Key Points
Chlorine, carbon, and sulfur LIBS emission lines suited for identification and quantification of salts in a basaltic matrix were identified
Above the measured detection limits, relative changes in salt content were observed with LIBS through univariate analysis
Results are applicable to the investigation of salts dispersed in basaltic rock on the Martian surface with ChemCam and future instruments
•Bacteriological survey of beef cattle bovine digital dermatitis (BDD) lesions.•One or more BDD-associated Treponema phylogroups were detected in 100% of lesions.•D. nodosus and F. necrophorum were ...present in 71% and 44% of lesions, respectively.•A spirochete isolated from a BDD lesion may represent a novel taxa of Treponema.•Evidence of a shared etiopathogenesis between sheep, dairy and beef cattle lesions.
Bovine digital dermatitis (BDD) is an infective foot disease commonly reported in dairy cattle where Treponema are considered as the primary causative infectious agents. There still remains little definitive information on the etiology of BDD in beef cattle suggesting further investigations are warranted. Beef BDD lesions (n=34) and healthy beef foot tissues (n=38) were analysed by PCR for three BDD-associated Treponema phylogroups and also for Dichelobacter nodosus and Fusobacterium necrophorum. Spirochete culture was attempted on all BDD lesion samples. One or more BDD-associated Treponema phylogroups were detected in 100% of beef BDD lesions. “Treponema medium/Treponema vincentii-like”, “Treponema phagedenis-like” and Treponema pedis spirochetes were identified in 27/34 (79%), 31/34 (91%) and 24/34 (71%) of BDD lesions, respectively. No BDD-associated treponeme DNA was amplified from beef healthy foot tissues. D. nodosus and F. necrophorum were present in 24/34 (71%) and 15/34 (44%) of lesions and 10/38 (26%) and 12/38 (32%) of healthy foot tissues, respectively. Twenty spirochetes were isolated from beef BDD lesions; 19 were representatives of the three BDD-associated Treponema phylogroups. One spirochete isolate shared less than 97% 16S rRNA gene similarity to the three cultivable BDD-associated Treponema phylogroups and therefore may represent a novel taxa of Treponema. Upon comparison, sheep contagious ovine digital dermatitis (CODD), dairy cattle and beef cattle BDD lesions appear to have extremely similar bacteriological data and therefore provides evidence of a shared etiopathogenesis posing concerns for cross-species transmission.
Semantic dementia is a sporadic neurodegenerative disorder characterized by the progressive erosion of semantic processing and is one of the canonical subtypes of frontotemporal lobar degeneration. ...This study aimed to characterize the pattern of global and regional longitudinal brain atrophy in semantic dementia and to identify imaging biomarkers that could underpin therapeutic trials.
Twenty-one patients with semantic dementia (including eight pathologically confirmed cases) underwent whole-brain and region-of-interest analyses on volumetric brain MRI scans at two time points. Sample size estimates for trials were subsequently calculated using these data.
Mean (SD) whole-brain atrophy rate was 39.6 (31.9) mL/y 3.2 (12.0) mL/y in controls, with ventricular enlargement of 8.9 (4.4) mL/y 1.0 (1.0) mL/y in controls. All patients had a smaller left temporal lobe at baseline left mean 31.9 (6.9) mL, right mean 49.2 (9.5) mL; p < 0.0001; however, the mean rate of atrophy was significantly greater in the right temporal lobe right 3.9 (1.7) mL/y, left 2.8 (1.2) mL/y; p = 0.02. Similarly, whereas the left hippocampus was smaller at baseline, the mean atrophy rate was significantly greater in the right hippocampus. Using the atrophy rates generated, sample size requirements for clinical trials were found to be smallest for temporal lobe measurement.
These findings show that the rate of tissue loss in the right temporal lobe overtakes the left temporal lobe as semantic dementia evolves, consistent with the later development of symptoms attributable to right temporal lobe dysfunction. Furthermore, our findings demonstrate that MRI measures of temporal lobe volume loss could provide a feasible and sensitive index of disease progression in semantic dementia.
The Chemistry Camera (ChemCam) instrument onboard Curiosity can detect minor and trace elements such as lithium, strontium, rubidium, and barium. Their abundances can provide some insights about ...Mars' magmatic history and sedimentary processes. We focus on developing new quantitative models for these elements by using a new laboratory database (more than 400 samples) that displays diverse compositions that are more relevant for Gale crater than the previous ChemCam database. These models are based on univariate calibration curves. For each element, the best model is selected depending on the results obtained by using the ChemCam calibration targets onboard Curiosity. New quantifications of Li, Sr, Rb, and Ba in Gale samples have been obtained for the first 1000 Martian days. Comparing these data in alkaline and magnesian rocks with the felsic and mafic clasts from the Martian meteorite NWA7533—from approximately the same geologic period—we observe a similar behavior: Sr, Rb, and Ba are more concentrated in soluble‐ and incompatible‐element‐rich mineral phases (Si, Al, and alkali‐rich). Correlations between these trace elements and potassium in materials analyzed by ChemCam reveal a strong affinity with K‐bearing phases such as feldspars, K‐phyllosilicates, and potentially micas in igneous and sedimentary rocks. However, lithium is found in comparable abundances in alkali‐rich and magnesium‐rich Gale rocks. This very soluble element can be associated with both alkali and Mg‐Fe phases such as pyroxene and feldspar. These observations of Li, Sr, Rb, and Ba mineralogical associations highlight their substitution with potassium and their incompatibility in magmatic melts.
Key Points
Revised Li, Sr, Rb, and Ba abundances have been obtained with updated univariate calibrations
The trace element abundances of alkaline and magnesian rocks are similar to the composition of monzonitic and basaltic clasts in NWA7533
Alkali trace element enrichments are associated with K‐bearing minerals such as alkali feldspars, K‐phyllosilicates, and probably micas
•Martian soils are analyzed for the first time at sub millimeter scale.•Three different groups of coarse grains have been distinguished.•Fine particles seem to derive from one group of coarse ...grains.•Presence of amorphous component in fine particles and some coarse grains.•Fine particles have undergone limited interaction with water.
The ChemCam instrument onboard the Curiosity rover provides for the first time an opportunity to study martian soils at a sub-millimeter resolution. In this work, we analyzed 24 soil targets probed by ChemCam during the first 250sols on Mars. Using the depth profile capability of the ChemCam LIBS (Laser-Induced Breakdown Spectroscopy) technique, we found that 45% of the soils contained coarse grains (>500μm). Three distinct clusters have been detected: Cluster 1 shows a low SiO2 content; Cluster 2 corresponds to coarse grains with a felsic composition, whereas Cluster 3 presents a typical basaltic composition. Coarse grains from Cluster 2 have been mostly observed exposed in the vicinity of the landing site, whereas coarse grains from Clusters 1 and 3 have been detected mostly buried, and were found all along the rover traverse. The possible origin of these coarse grains was investigated. Felsic (Cluster 2) coarse grains have the same origin as the felsic rocks encountered near the landing site, whereas the origin of the coarse grains from Clusters 1 and 3 seems to be more global. Fine-grained soils (particle size<laser beam diameter which is between 300 and 500μm) show a homogeneous composition all along the traverse, different from the composition of the rocks encountered at Gale. Although they contain a certain amount of hydrated amorphous component depleted in SiO2, possibly present as a surface coating, their overall chemical homogeneity and their close-to-basaltic composition suggest limited, or isochemical alteration, and a limited interaction with liquid water. Fine particles and coarse grains from Cluster 1 have a similar composition, and the former could derive from weathering of the latter. Overall martian soils have a bulk composition between that of fine particles and coarse grains. This work shows that the ChemCam instrument provides a means to study the variability of soil composition at a scale not achievable by bulk chemical analyses.
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