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Dissolution rates of naturally occurring gas hydrates vary by orders of magnitude across studies suggesting that environmental factors may influence hydrate dissolution. To determine the role that sediment cover plays in hydrate dissolution, we used a mini-pore fluid array sampler (mPFA) to continuously collect sediment porewater adjacent to a hydrate outcrop and maintain it at in situ pressure for later analysis. This allowed us to measure in situ dissolved hydrocarbon concentrations in the porewater over time without sample loss due to degassing. We deployed the mPFA at a hydrate outcrop at Barkley Canyon on the Cascadia Margin for nine months. This novel approach yielded concentration data that were used to determine the steady-state dissolution rate of the hydrate outcrop and test predictions of the diffusion-control model for dissolution in the field. In the lab, we conducted a series of experiments with artificial hydrate to directly compare dissolution rates between exposed and sediment-covered hydrate. The dissolution rate of the natural hydrate outcrop covered with sediment was 0.06 cm y − 1 . The laboratory experiments of sediment-covered hydrate yielded dissolution rates of 0.6 ± 0.5 cm y − 1 (n = 5). In both laboratory and field observations, the dissolution rate of hydrates exposed directly to bulk water (3.9 ± 1.7 cm y − 1 and 3.5 cm y − 1 respectively) was at least an order of magnitude faster than the dissolution rate of sediment covered hydrate. These results are consistent with expectations of diffusion-control and support this model of hydrate dissolution. In nature, sediment may account for the persistence of hydrate in otherwise methane-depleted environments by increasing the diffusive boundary layer and slowing the rate of molecular diffusion via porosity/tortuosity effects. We provide a number of “Lessons Learned” for improving the instrument design and for consideration during future studies. [ABSTRACT FROM AUTHOR]

Aim: The aim of this study was to re-evaluate our protocol for the management of isolated axillary lymphadenopathy (ALP) on mammographic screening. Methods: In a retrospective review of 200,716 women screened at the South West London Breast Screening Service (SWLBSS) over 7 years, 72 women with ALP with an otherwise normal mammogram were identified. Thirteen patients were not recalled, nine of who had a known underlying diagnosis and the remainder had longstanding unchanged mammograms. Fifty-nine patients were recalled for further clinical assessment and investigations, including ultrasound, further mammographic views, fine-needle aspiration cytology (FNAC), blood tests and a chest radiograph. Those with a definite diagnosis were referred for appropriate management and those with benign reactive cytology on FNAC reviewed at 6 weeks with subsequent referral for excision of persisting abnormal nodes. Results: The ultimate diagnosis was benign in 45 cases: 26 benign reactive changes, 11 arthritides, five with dermatological and viral conditions and three with tuberculosis. Malignancy was diagnosed in 13 cases: four with metastatic breast carcinoma and nine with lymphoma/leukaemia. The total number of newly diagnosed malignancies was 20% of women recalled. Another 5% of patients had active tuberculosis. Of the 22 patients with benign reactive cytology, one had significant pathology on excision biopsy: tuberculosis. Over 95% of the results from excision biopsy in these patients did not alter management. Conclusion: In the majority of patients, the FNAC results were representative of the final excision pathology. The present study suggests that excision biopsy could be omitted for those patients whose FNAC and culture are negative. [ABSTRACT FROM AUTHOR]

Samples of human dental enamel and hydroxyapatite were equilibrated at 5 mg/40 ml for 9 days at 37 °C with acetate buffers adjusted to a range of saturations with respect to hydroxyapatite. Sigmoidal apparent solubility distributions, in which the fraction dissolved was plotted against -log(ion activity product for hydroxyapatite) (pIHA), were constructed. About 10% of the hydroxyapatite and 14% of the enamel was very soluble, dissolving even at pIHA 55. The apparent solubility distributions for both solids were invariant with pH (4.5, 5.0, 5.5), within experimental error, showing that solubility was controlled by a phase with the stoichiometry of hydroxyapatite, probably in the form of a surface layer or complex on the crystals, in agreement with other studies on carbonate-apatites and bone mineral. The pIHA at 50% dissolution was employed as an average value. The pIHA (50%) values for pooled data (58.76 for enamel and 60.17 for hydroxyapatite) were lower than the respective pIHA previously measured by conventional equilibration techniques. However, the average pIHA measured for enamel was higher than that obtained by the same technique in another study, possibly because of differences in specimen preparation and equilibration time. The possible implications of the findings for understanding the process of dental caries are discussed. [Copyright &y& Elsevier]

Two sets of non-stoichiometric apatites (Ca-deficient apatites) were prepared from calcium phosphate solutions by homogeneous precipitation through the hydrolysis of formamide at 95°C. One set of products contained monetite (CaHPO4) and apatite, whilst the second, with more formamide, contained only apatite. Rietveld whole pattern fitting structure refinements were undertaken on all samples, and chemical analyses, IR and NMR spectroscopy, on the second set of samples. The Ca/P mol ratio was 1.596. Rietveld analysis gave lattice parameters a=9.4729(20) and c=6.8855(9) A˚ and showed that Ca2+ ions were lost exclusively from Ca2 sites, and that the PO4 tetrahedron volume and P–O bonds were 4.4% and 1.4% smaller, respectively, than in hydroxyapatite (OHAp). Formate, HCO2−, was clearly visible in the IR and NMR spectra, but the diffraction studies showed it was not present as a separate crystalline phase. Chemical analysis gave 5.8 wt % formate. We propose that the enlarged a-axis compared with OHAp (a=9.4243(55) A˚) and reduced PO4 dimensions and P occupancy are, respectively, caused by the partial replacement of OH− and PO43− ions in the structure by HCO2− ions. These substitutions would parallel the similar known substitutions of CO32− ions in precipitated carbonate apatites. [Copyright &y& Elsevier]

Provides information on a study which examined the structure and composition of human dental enamel apatite. Methodology of the study; Results and discussion on the study.

Abstract: Objectives: Fine-grained, high strength, translucent leucite dental glass-ceramics are synthesized via controlled crystallization of finely milled glass powders. The objectives of this study were to utilize high speed planetary milling of an aluminosilicate glass for controlled surface crystallization of nano-scale leucite glass-ceramics and to test the biaxial flexural strength. Methods: An aluminosilicate glass was synthesized, attritor or planetary milled and heat-treated. Glasses and glass-ceramics were characterized using particle size analysis, X-ray diffraction and scanning electron microscopy. Experimental (fine and nanoscale) and commercial (Ceramco-3, IPS Empress Esthetic) leucite glass-ceramics were tested using the biaxial flexural strength (BFS) test. Gaussian and Weibull statistics were applied. Results: Experimental planetary milled glass-ceramics showed an increased leucite crystal number and nano-scale median crystal sizes (0.048–0.055μm2) as a result of glass particle size reduction and heat treatments. Experimental materials had significantly (p <0.05) higher mean BFS and characteristic strength values than the commercial materials. Attritor milled and planetary milled (2h) materials showed no significant (p >0.05) strength difference. All other groups’ mean BFS and characteristic strengths were found to be significantly different (p <0.05) to each other. The mean (SD) MPa strengths measured were: Attritor milled: 252.4 (38.7), Planetary milled: 225.4 (41.8) [4h milling] 255.0 (35.0) [2h milling], Ceramco-3: 75.7 (6.8) and IPS Empress: 165.5 (30.6). Significance: Planetary milling enabled synthesis of nano-scale leucite glass-ceramics with high flexural strength. These materials may help to reduce problems associated with brittle fracture of all-ceramic restorations and give reduced enamel wear. [Copyright &y& Elsevier]

We have evaluated the impact of the R2 Imagechecker, a CAD system for mammography in two studies using both radiologists and appropriately trained radiographers.We first compared the performance of 30 radiologists and 15 film-reading radiographers reading 120 normals and 60 cancer cases. The readers read all cases, with and without CAD prompts. The cancer cases included 40 screening-detected cancers and 20 interval cancers. We looked at sensitivity and specificity and found no significant difference between radiologists and film-reading radiographers with or without CAD.Our second study was designed to maximise the potential of CAD and included an additional 40 subtle cancers, previously missed by radiologists, but which R2 was able to prompt.We have carried out an evaluation of CAD involving a large number of film-readers and two test sets of cancers drawn from the UK screening programme. Our results suggest that the impact of prompts on readers'' recall decisions is substantially lower than previous authors had anticipated. [Copyright &y& Elsevier]

This study aims to constrain the base of the hydrates stability field in structurally complexsites using the case of Woolsey Mound, a fault-controlled, transient, thermogenic hydrates system, in Mississippi Canyon Block 118, northern Gulf of Mexico. We have computed the base of the hydrates stability field integrating results from a recent heat-flow survey, designed to investigate geothermal anomalies along fault zones which exhibit different fluid flux regimes. An advanced “compositional” simulator was used to model hydrate formation and dissociation at Woolsey Mound and addresses the following hypotheses: 1. Migrating thermogenic fluids alter thermal conditions of the Hydrate Stability Zone (HSZ), so heat-flow reflects fault activity; 2. Gas hydrate formation and dissociation vary temporally at active faults, temporarily sealing conduits for migration of thermogenic fluids; 3. High salinity and inclusion of thermogenic gases with higher molecular weight than methane produce opposite effects on the depth to the bottom of the hydrate stability zone. Applications of results include identifying and quantifying hydrate deposits in shallow sediments using an interdisciplinary approach that includes multiple resolution seismic data evaluation, geological and geochemical groundtruthing and heat-flow analyses as a proxy for activity along faults. [ABSTRACT FROM AUTHOR]

Abstract: Fluorapatite glass-ceramics are osteoconductive, and glass-ceramics containing fluorapatite crystals in a bioactive silicate glass matrix can combine the benefits of fluorapatite with the bone-regenerative properties of bioactive glasses. High phosphate content (around 6mol% P2O5) bioactive glasses (SiO2–P2O5–CaO–Na2O–CaF2) were prepared by a melt-quench route. Structural investigation using density measurements and calculations confirmed the presence of phosphorus as orthophosphate. Upon heat treatment, the glasses crystallised to mixed sodium calcium fluoride orthophosphates (sodium-containing compositions) and fluorapatite (sodium-free composition). Fluoride suppressed spontaneous crystallisation, allowing formation of glass-ceramics by controlled crystallisation. A notable feature is that silicate network polymerisation and network connectivity did not change during crystallisation, resulting in orthophosphate and fluorapatite crystals embedded within a bioactive glass matrix. By keeping the phosphate content high and the sodium content low, fluorapatite glass-ceramics can be obtained, while not affecting the structure of the bioactive silicate glass phase. [Copyright &y& Elsevier]

Aim: To investigate the effect of image processing on cancer detection in mammography.Methods and Materials: An observer study was performed using 349 digital mammography images of women with normal breasts, calcification clusters, or soft-tissue lesions including 191 subtle cancers. Images underwent two types of processing: FlavourA (standard) and FlavourB (added enhancement). Six observers located features in the breast they suspected to be cancerous (4,188 observations). Data were analysed using jackknife alternative free-response receiver operating characteristic (JAFROC) analysis. Characteristics of the cancers detected with each image processing type were investigated.Results: For calcifications, the JAFROC figure of merit (FOM) was equal to 0.86 for both types of image processing. For soft-tissue lesions, the JAFROC FOM were better for FlavourA (0.81) than FlavourB (0.78); this difference was significant (p=0.001). Using FlavourA a greater number of cancers of all grades and sizes were detected than with FlavourB. FlavourA improved soft-tissue lesion detection in denser breasts (p=0.04 when volumetric density was over 7.5%) CONCLUSIONS: The detection of malignant soft-tissue lesions (which were primarily invasive) was significantly better with FlavourA than FlavourB image processing. This is despite FlavourB having a higher contrast appearance often preferred by radiologists. It is important that clinical choice of image processing is based on objective measures. [ABSTRACT FROM AUTHOR]