An investigation into the depth of penetration of low level laser therapy through the equine tendon in vivo

Low level laser therapy (LLLT) is frequently used in the treatment of wounds, soft tissue injury and in pain management. The exact penetration depth of LLLT in human tissue remains unspecified. Similar uncertainty regarding penetration depth arises in treating animals. This study was designed to test the hypothesis that transmission of LLLT in horses is increased by clipping the hair and/or by cleaning the area to be treated with alcohol, but is unaffected by coat colour. A LLLT probe (810 nm, 500 mW) was applied to the medial aspect of the superficial flexor tendon of seventeen equine forelimbs in vivo. A light sensor was applied to the lateral aspect, directly opposite the laser probe to measure the amount of light transmitted. Light transmission was not affected by individual horse, coat colour or leg. However, it was associated with leg condition (F = 4.42, p = 0.0032). Tendons clipped dry and clipped and cleaned with alcohol, were both associated with greater transmission of light than the unprepared state. Use of alcohol without clipping was not associated with an increase in light transmission. These results suggest that, when applying laser to a subcutaneous structure in the horse, the area should be clipped and cleaned beforehand

Deformation-aided segregation of Fe-S liquid from olivine under deep Earth conditions: Implications for core formation in the early solar system

The planets and larger rocky bodies of the inner solar system are differentiated, and consist of metallic, iron-rich cores surrounded by thick shells of silicate. Core formation in these bodies, i.e. the segregation of metal from silicate, was a key process in the early solar system, and one which left a lasting geochemical signature. It is commonly assumed that extensive silicate melting and formation of deep magma oceans was required to initiate core formation, due to the inability of iron-rich melts to segregate from a solid silicate matrix. Here we assess the role of deformation in aiding segregation of core-forming melts from solid silicate under conditions of planetary deep interiors. Low-strain rate, high-pressure/ temperature deformation experiments and high-resolution 2-D and 3-D textural analysis demonstrate that deformation fundamentally alters iron-rich melt geometry, promoting wetting of silicate grain boundaries and formation of extensive micron to sub-micron width Fe-rich melt bands. Deformation-aided Fe-S melt networks noted here contrast those observed in higher finite strain experiments conducted at lower pressure, and may reveal either an alternative mechanism for melt segregation at higher pressures, or an early stage process of melt segregation. Results suggest, however, that core-mantle chemical equilibration cannot be assumed in models of planetary formation, and that instead, the chemistry of rocky planets may record a complex, multi-stage process of core formation.This work was supported by the University Of Edinburgh (Principal’s Career Development studentship), the Natural Environment Research Council under NE/I016333/1, Science and Technology Facilities Council, European Synchrotron Radiation Facility, and the EPSRC for the Manchester X-ray Imaging Facility under EP/ F007906/1 and EP/F028431/1

The nature of organic records in impact excavated rocks on Mars

Impact ejected rocks are targets for life detection missions to Mars. The Martian subsurface is more favourable to organic preservation than the surface owing to an attenuation of radiation and physical separation from oxidising materials with increasing depth. Impact events bring materials to the surface where they may be accessed without complicated drilling procedures. On Earth, different assemblages of organic matter types are derived from varying depositional environments. Here we assess whether these different types of organic materials can survive impact events without corruption. We subjected four terrestrial organic matter types to elevated pressures and temperatures in piston-cylinder experiments followed by chemical characterisation using whole-rock pyrolysis-gas chromatography-mass spectrometry. Our data reveal that long chain hydrocarbon-dominated organic matter (types I and II; mainly microbial or algal) are unresistant to pressure whereas aromatic hydrocarbondominated organic matter types (types III and IV; mainly land plant, metamorphosed or degraded, displaying some superficial chemical similarities to abiotic meteoritic organic matter) are relatively resistant. This suggests that the impact excavated record of potential biology on Mars will be unavoidably biased, with microbial organic matter underrepresented while metamorphosed, degraded or abiotic meteoritic organic matter types will be selectively preserved

A single-crystal neutron diffraction study of hambergite, Be2BO3(OH,F)

The crystal chemistry and crystal structure of hambergite from the Anjanabonoina mine, Madagascar [Be2BO3(OH)(0.96)F-0.04, Z = 8, a = 9.762(2), b = 12.201(2), c = 4.430(1) angstrom, V = 527.6(2) angstrom(3), space group Pbca], were reinvestigated by means of electron microprobe analysis in wavelength-dispersive mode, secondary-ion mass spectrometry, single-crystal X-ray and neutron Laue diffraction. Chemical analyses show only a small amount of F (0.7-0.8 wt%, approximately 0.04 atoms per formula unit) substituting OH and no other substituent at a significant level. An anisotropic neutron structural refinement has been performed with final agreement index R-1 = 0.0504 for 76 refined parameters and 1430 unique reflections with F-o>4 sigma(F-o). The geometry of the hydroxyl group and hydrogen bonding in hambergite is now well defined: (1) only one independent H site was located and the O4-H distance, corrected for "riding motion," is similar to 0.9929 angstrom; (2) only one hydrogen bond appears to be energetically favorable, with a symmetry-related O4 as acceptor and with O4 center dot center dot center dot O4 = 2.904(1) angstrom, H center dot center dot center dot O4 = 1.983(1) angstrom, and O4-H center dot center dot center dot O4 = 157.5(1)degrees. In other words, O4 sites act both as donor and as acceptor of the hydrogen bond, with a zigzag chain of H-bonds along [001]. The hydrogen-bonding scheme in hambergite found in this study is consistent with the pleochroic scheme of the infrared spectra previously reported, with two intensive modes ascribable to stretching vibrations of the hydroxyl group, at 3415 and 3520 cm(-1), respectively. The two modes suggest at least two distinct hydrogen-bonding environments, ascribable to the presence of oxygen and fluorine at the acceptor site. © 2012, Mineralogical Society of Americ

Apatite: A new redox proxy for silicic magmas?

The oxidation states of magmas provide valuable information about the release and speciation of volatile elements during volcanic eruptions, metallogenesis, source rock compositions, open system magmatic processes, tectonic settings and potentially titanium (Ti) activity in chemical systems used for Ti-dependent geothermometers and geobarometers. In this paper we explore the use of Mn in apatite as an oxybarometer in intermediate and silicic igneous rocks. Increased Mn concentrations in apatite in granitic rocks from the zoned Criffell granitic pluton (southern Scotland) correlate with decreasing Fe2O3 (Fe3+ 24 ) and Mn in the whole-rock and likely reflect increased Mn2+/Mn3+ and greater compatibility of Mn2+ 25 relative to Mn3+ in apatite under reduced conditions. Fe3+/Fe2+ 26 ratios in biotites have previously been used to calculate oxygen fugacities (fO2) in the outer zone granodiorites and inner zone granites where redox conditions have been shown to change from close to the magnetite hematite buffer to close to the nickel-nickel oxide buffer respectively (Stephens et al., 1985). This trend is apparent in apatite Mn concentrations from a range of intermediate to silicic volcanic rocks that exhibit varying redox states and are shown to vary linearly and negatively with log fO2, such that log fO2 = -0.0022(±0.0003) Mn (ppm) – 9.75(±0.46) Variations in the Mn concentration of apatites appear to be largely independent of differences in the Mn concentration of the melt. Apatite Mn concentrations may therefore provide an independent oxybarometer that is amenable to experimental calibration, with major relevance to studies on detrital mineral suites, particularly those containing a record of early Earth redox conditions, and on the climatic impact of historic volcanic eruptions