Humans accumulate large numbers of inorganic particles in their lungs over a lifetime. Whether this causes or contributes to debilitating disease over a normal lifespan depends on the type and ...concentration of the particles. We developed and tested a protocol for in situ characterization of the types and distribution of inorganic particles in biopsied lung tissue from three human groups using field emission scanning electron microscopy (FE-SEM) combined with energy dispersive spectroscopy (EDS). Many distinct particle types were recognized among the 13 000 particles analyzed. Silica, feldspars, clays, titanium dioxides, iron oxides and phosphates were the most common constituents in all samples. Particles were classified into three general groups: endogenous, which form naturally in the body; exogenic particles, natural earth materials; and anthropogenic particles, attributed to industrial sources. These in situ results were compared with those using conventional sodium hypochlorite tissue digestion and particle filtration. With the exception of clays and phosphates, the relative abundances of most common particle types were similar in both approaches. Nonetheless, the digestion/filtration method was determined to alter the texture and relative abundances of some particle types. SEM/EDS analysis of digestion filters could be automated in contrast to the more time intensive in situ analyses.
•Asphaltenes used to determine fate of Deepwater Horizon (DWH) spilled oil.•An average 61% of the original oil lost by photo-oxidation and evaporation.•Oxygen content of asphaltenes from spilled oil ...increases by a factor of ten.•Asphaltenes from spilled oils are depleted in 12C by more than 1‰.
The composition and content of asphaltenes in spilled and original wellhead oils from the Deepwater Horizon (DWH) incident provide information on the amount of original oil lost and the processes most responsible for the losses within the first 80days of the active spill. Spilled oils were collected from open waters, coastal waters and coastal sediments during the incident. Asphaltenes are the most refractory component of crude oils but their alteration in the spilled oils during weathering prevents them from being used directly as a conservative component to calculate original oil losses. The alteration is reflected by their increase in oxygen content and depletion in 12C. Reconnaissance experiments involving evaporation, photo-oxidation, microbial degradation, dissolution, dispersion and burning indicate that the combined effects of photo-oxidation and evaporation are responsible for these compositional changes. Based on measured losses and altered asphaltenes from these experiments, a mean of 61±3vol% of the original oil was lost from the surface spilled oils during the incident. This mean percentage of original oil loss is considerably larger than previous estimates of evaporative losses based on only gas chromatography (GC) amenable hydrocarbons (32–50vol%), and highlights the importance of using asphaltenes, as well as GC amenable parameters in evaluating original oil losses and the processes responsible for the losses.
Molecular and cellular mechanisms underlying resistance/low responsiveness to antiangiogenic compounds are under extensive investigations. Both populations of tumor and stroma (nontumor compartment) ...seem to contribute in inherent/acquired resistance to antiangiogenic therapy. Here, investigating in vivo efficacy of sunitinib in experimental models resulted in the identification of tumors that were resistant/sensitive to the therapy. Analysis of tumor protein lysates indicated a greater concentration of hepatocyte growth factor (HGF) in resistant tumors than in sensitive ones. In addition, using flow cytometry, c-Met expression was found to be significantly higher in endothelial cells than in tumor cells, suggesting that HGF might target the vascular endothelial cells in resistant tumors. Combination of sunitinib and a selective c-Met inhibitor significantly inhibited tumor growth compared with sunitinib or c-Met inhibitor alone in resistant tumors. Histology and in vitro analyses suggested that combination treatment mainly targeted the vasculature in the resistant tumors. Conversely, systemic injection of HGF in the sensitive tumor models conferred resistance to sunitinib through maintenance of tumor angiogenesis. In conclusion, our study indicates a role for HGF/c-Met pathway in development of resistance to antiangiogenic therapy and suggests a potential strategy to circumvent resistance to vascular endothelial growth factor receptor tyrosine kinase inhibitor in the clinic.
Ultra-high molecular weight polyethylene (UHMWPE) remains the sole polymer bearing material for use in orthopedic implants and its behavior has been studied extensively. Various techniques, such as ...crosslinking, have been employed to reduce the total wear volume. However, little is known about the actual wear mechanisms that contribute to the removal of debris from the bulk. A nearly universal observation of the wear surfaces after multidirectional sliding of UHMWPE is the presence of regularly-spaced parallel ripples whose wavelength closely matches debris size. In spite of the fact that this phenomenon has been observed for decades in both retrieved implants as well as wear simulation studies, the specific causes of the rippled topology have not yet been identified. Proposed mechanisms have included abrasion, crystallinity effects, fatigue, stick-slip behavior, thermal softening, and Schallamach waves. This investigation involved an experimental and computational factorial test design to determine the role of various parameters involved in the rippling phenomenon. The authors employed a film buckling theoretical model and applied it to UHMWPE using a finite element modeling approach. Wear testing was performed on a two-axis tribometer to expose the polymer to multi-directional sliding. Characteristic ripples developed on all wear surfaces, but with varying periodicity. Two regimes of the ripple phenomenon were observed: localized long wavelength (2.2–3.2 µm) ripples which appeared to dominate before steady state wear was established, and long-range shorter-wavelength (approximately 1 µm) ripples which indicated a steady-state condition. Surprisingly, feature wavelength showed little dependence on roughness or temperature but were slightly affected by contact pressure. The wear surfaces were cleaved and examined by SEM to gauge the thickness of the plastically deformed quasi-film layer. These layers were on the order of 10–20 nm thick. Further examination of the surfaces confirms the development of a deformed layer which acts similarly to a buckled thin film.
•Two characteristic wavelength regimes of UHMWPE surface ripple were discovered.•The rippled topology agrees well with an existing buckling thin-film model.•A thin plastically deformed layer is formed at the wear interface and acts as a film.
Water withdrawals and discharges from municipal wastewater-treatment plants in semiarid regions result in more urban streams becoming dependent on wastewater effluent for base flows. Such ...wastewater-effluent-dominated streams support perennial-stream ecosystems that would not otherwise exist. At the same time, ecosystems downstream of effluent discharges can improve water quality, support water re-use, create habitat, and provide urban amenities. By identifying measures of success for biota, habitat, hydrology, geomorphology, and water quality, water managers can better design, operate, and monitor effluent-dominated water courses under future climate conditions. This requires the development of clearly defined ecological and social objectives, as well as a better understanding of the consequences of increasing reliance on wastewater effluent to sustain the biota of effluent-dominated streams. Successful quantification of the costs and benefits of these projects is likely to attract the attention of agencies and communities that have the power to turn the environmental perturbations associated with effluent discharges into new forms of environmental enhancement.
Ultra-high molecular weight polyethylene (UHMWPE) remains the primary bearing material for use in artificial joints, but the longevity of these implants is still hindered by an osteolytic immune ...system response initiated by sub-micron sized wear debris released from the UHMWPE bulk component. Studies have shown that the severity of the immune system response is linked to particle size. Current treatments for reducing this effect focus on reducing the total volume of wear, but do not directly address particle size due to a limited understanding of the mechanisms involved in producing such small debris. Directly observing these mechanisms is inherently challenging, but indirect methods, such as debris characterization and wear surface analysis, suggest that multiple mechanisms are present throughout a wear process, including a poorly understood plastic deformation process. In this study, finite element models exhibited areas of plastic deformation that were of the same size scale as the relevant debris, and novel experimental techniques were used to verify these regions of deformation. Using this insight, equations based on surface buckling were derived that accurately describe the characteristic rippling formations found on the surface of the UHMWPE bulk. This information can be used to influence the size and shape of submicron wear debris.
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