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Abstract: A low-cost, low-pressure cold spray unit was used to fabricate tungsten carbide (WC)-based metal matrix composite (MMC) coatings. A sintered and crushed WC-based powder was mixed with nickel powder, forming various compositions of mechanical blends. Scanning electron microscopy (SEM), coupled with image analysis, Vickers micro-hardness, and X-ray diffraction (XRD) was used to characterize the coatings. Image analysis was used to determine the WC content in the coating and the mean free path between the reinforcing particles. The WC content in the coating increased as the WC content in the powder blend increased. Each coating fabricated by the various mechanical blend compositions had a non-homogeneous distribution of the hard WC reinforcing particles embedded in the nickel matrix. However, as the WC content in the powder increased, the coating porosity decreased and the WC deposition efficiency increased. An inversely proportional relationship between hardness and mean free path between the reinforcing WC particles was observed, where a decrease in mean free path led to an increase in hardness. The hardness of each MMC coating was predicted using the rule of mixtures (ROM) method and compared to the experimental hardness values. However, the ROM method did not completely describe the strengthening mechanism of the MMC coatings because densification, plastic deformation, and adiabatic shear instability played a role, especially for the coatings with a lower WC content. [Copyright &y& Elsevier]

Trees are efficient scavengers of particulate matter and are characterised by higher rates of dry deposition than other land types. To estimate the potential of urban tree planting for the mitigation of urban PM10 concentrations, an atmospheric transport model was used to simulate the transport and deposition of PM10 across two UK conurbations (the West Midlands and Glasgow). Tree planting was simulated by modifying the land cover database, using GIS techniques and field surveys to estimate reasonable planting potentials. The model predicts that increasing total tree cover in West Midlands from 3.7% to 16.5% reduces average primary PM10 concentrations by 10% from 2.3 to 2.1μgm−3 removing 110ton per year of primary PM10 from the atmosphere. Increasing tree cover of the West Midlands to a theoretical maximum of 54% by planting all available green space would reduce the average PM10 concentration by 26%, removing 200ton of primary PM10 per year. Similarly, for Glasgow, increasing tree cover from 3.6% to 8% reduces primary PM10 concentrations by 2%, removing 4ton of primary PM10 per year. Increasing tree cover to 21% would reduce primary PM10 air concentrations by 7%, removing 13ton of primary PM10 per year. [Copyright &y& Elsevier]

Abstract: Trees have been widely quoted as effective scavengers of both gaseous and particulate pollutants from the atmosphere. Recent work on the deposition of urban aerosols onto woodland allows the effect of tree planting strategies on airborne aerosol concentrations to be quantified and considered within the planning process. By identifying the potential planting locations in the local authority area, and applying them within a dispersion and deposition model, the potential magnitude of reduction in the ambient concentration of PM10, achievable through urban tree planting, has been quantified for two UK cities. As part of the Environmental Information Systems for Planners (EISP), flow diagrams, based on planning decisions, have incorporated output from the model to make decisions on land use planning ranging from development plans and strategic planning, to development control. In this way, for any new developments that contribute to the local PM10 level, the mitigation by planting trees can be assessed, and in some cases, reductions can be sufficient to meet air quality objectives for PM10. [Copyright &y& Elsevier]

OBJECTIVE: We sought to investigate the clinical determinants of intestinal failure and death in preterm infants with surgical NEC. METHODS: Retrospective comparison of clinical information between Group A = intestinal failure (Parenteral nutrition (PN) >90 days) and death and Group B = survivors and with PN dependence < 90 days in preterm infants with surgical NEC. RESULTS: Group A (n = 99/143) had a lower mean gestational age (26.4 weeks [SD3.5] vs. 29.4 [SD 3.5]; p = 0.013), lower birth weight (873 gm [SD 427g] vs. 1425 gm [894g]; p = <0.001), later age of NEC onset (22 days [SD20] vs. 16 days [SD 17]; p = 0.128), received surgery later (276 hours [SD 544] vs. 117 hours [SD 267]; p = 0.032), had cholestasis, received dopamine (80.6% vs. 58.5%; p = 0.010) more frequently and had longer postoperative ileus time (19.8 days [SD 15.4] vs. 11.8 days [SD 6.5]; p = <0.001) and reached full feeds later (93 days [SD 45] vs. 44 [SD 22]; p = <0.001) than Group B. On multivariate logistic regression, higher birth weight was associated with lower risk (OR 0.35, 95% CI 0.15–0.82; p = 0.016) of TPN > 90 days or death. Longer length of bowel resected (OR 1.76, 95% CI 1.02–3.02; p = 0.039) and longer postoperative ileus (OR 2.87, 95% CI 1.26–6.53; p = 0.011) were also independently associated with TPN >90days or death adjusted for gestational age and antenatal steroid treatment. CONCLUSION: In preterm infants with surgical NEC, clinical factors such as lower birth weight, longer bowel loss, and postoperative ileus days were significantly and independently associated with TPN >90 days or death. [ABSTRACT FROM AUTHOR]

Highlights: [•] Devolatilisation kinetics and analytical Py-GC/MS were conducted on Nigerian teak. [•] Low ash (<1%) and N (<1%) contents and relatively high HHV (19.8MJ/kg) for teak was found. [•] Variation in E between 222 and 300kJ/mol as a function of α was observed. [•] More than one-third of the chemical constituents were phenolic organic compounds. [Copyright &y& Elsevier]

Abstract: Porous titanium alloy-bioactive glass composite coatings were manufactured via the flame spray deposition process. The porous coatings, targeted for orthodontic and bone-fixation applications, were made from bioactive glass (45S5) powder blended with either commercially pure titanium (Cp-Ti) or Ti-6Al-4V alloy powder. Two sets of spray conditions, two metallic particle size distributions, and two glass particle size distributions were used for this study. Negative control coatings consisting of pure Ti-6Al-4V alloy or Cp-Ti were sprayed under both conditions. The as-sprayed coatings were characterized through quantitative optical cross-sectional metallography, X-ray diffraction (XRD), and ASTM Standard C633 tensile adhesion testing. Determination of the porosity and glassy phase distribution was achieved by using image analysis in accordance with ASTM Standard E2109. Theoretical thermodynamic and heat transfer modeling was conducted to explain experimental observations. Thermodynamic modeling was performed to estimate the flame temperature and chemical environment for each spray condition and a lumped capacitance heat transfer model was developed to estimate the temperatures attained by each particle. These models were used to establish trends among the choice of alloy, spray condition, and particle size distribution. The deposition parameters, alloy composition, and alteration of the feedstock powder size distribution had a significant effect on the coating microstructure, porosity, phases present, mechanical response, and theoretical particle temperatures that were attained. The most promising coatings were the Ti-6Al-4V-based composite coatings, which had bond strength of 20±2MPa (n =5) and received reinforcement and strengthening from the inclusion of a glassy phase. It was shown that the use of the Ti-6Al-4V-bioactive glass composite coatings may be a superior choice due to the possible osteoproductivity from the bioactive glass, the potential ability to support tissue ingrowth and vascular tissue, and the comparable strength to similar coatings. [Copyright &y& Elsevier]

Abstract: Cold gas dynamic spraying at low pressure (1MPa gage or 150psig) was used to fabricate Al–Al2O3 metal matrix composite (MMC) coatings onto 6061 Al alloy. The powder contained Al powder admixed with −10μm Al2O3 in fractions up to 90wt.%. Scanning electron microscopy (SEM), Vickers microhardness testing, and image analysis were conducted to determine the microstructure, properties, and volume fraction of reinforcing particles in the coatings. The coatings were then friction-stir processed (FSP) at tool rotation speeds of 894 or 1723RPM using a flat cylindrical tool. The Al2O3 content and hardness of the final MMC coatings increased with increasing fractions of Al2O3 particles in the feedstock powder, resulting in a maximum Al2O3 content of 48wt.% and a hardness of 85HV of the as-sprayed coating when 90wt.% Al2O3 was used in the feed powder blend. After FSP, the hardness of the MMC increased to a maximum of 137HV. The as-sprayed coatings contained Al2O3 particles that were segregated between the Al particles, and FSP was effective in dispersing these Al2O3 particles and decreasing their mean free path. It was suggested that this re-distribution and Al2O3 particle size refinement during FSP improved the hardness of the MMC coatings. [Copyright &y& Elsevier]

Abstract: Tungsten carbide (WC)-based metal matrix composite (MMC) coatings fabricated using a low-cost, low-pressure cold spray unit were subjected to ASTM standard G65 dry abrasion wear testing. A linear relationship was observed between the wear rate and hardness of the various MMC coatings. Rule of mixtures (ROM) and a modified wear theory was used to explain the wear rate and material removal from the various WC-based MMC coatings. In general, the MMC coatings had wear rates closer to the values predicted by the modified wear theory. Although the MMC coatings had low wear rates close to values predicted by the equal wear theory, the cross-sectional images of the worn coatings suggested that material removal may have occurred by mechanisms governed by the equal pressure theory, where portions of, or even, the entire reinforcing particle were removed with the nickel matrix. The mean free path between the WC-based reinforcing particles was used to explain the improvements in wear rate as a function of increasing WC content in the coating. The coatings with the highest WC content and lower mean free path between the reinforcing particles had the lowest wear rates that were comparable to high-velocity oxy-fuel (HVOF)-sprayed and high-pressure cold-sprayed WC-based coatings. [Copyright &y& Elsevier]