Recent demands for non-toxic antifouling technologies have led to increased interest in coatings based on silicone elastomers that 'release' macrofouling organisms when hydrodynamic conditions are sufficiently robust. However, these types of coatings accumulate diatom slimes, which are not released even from vessels operating at high speeds (>30 knots). In this study, adhesion strength and motility of three common fouling diatoms (Amphora coffeaeformis var. perpusilla (Grunow) Cleve, Craspedostauros australis Cox and Navicula perminuta Grunow) were measured on a poly-dimethylsiloxane elastomer (PDMSE) and acid-washed glass. Adhesion of the three species was stronger to PDMSE than to glass but the adhesion strengths varied. The wall shear stress required to remove 50% of cells from PDMSE was 17 Pa for Craspedostauros, 24 Pa for Amphora and >>53 Pa for Navicula; the corresponding values for glass were 3, 10 and 25 Pa. In contrast, the motility of the three species showed little or no correlation between the two surfaces. Craspedostauros moved equally well on glass and PDMSE, Amphora moved more on glass initially before movement ceased and Navicula moved more on PDMSE before movement ceased. The results show that fouling diatoms adhere more strongly to a hydrophobic PDMSE surface, and this feature may contribute to their successful colonization of low surface energy, foul-release coatings. The results also indicate that diatom motility is not related to adhesion strength, and motility does not appear to be a useful indicator of surface preference by diatoms.

Relative permeability hysteresis has been measured for a water-wet outcrop rock sample and a mixed-wet reservoir core. For the oil phase, imbibition and drainage relative permeability curves differed significantly. The difference was much less pronounced for the water phase. Scanning curves, which characterize transitions between imbibition and drainage curves, were also measured. A notable characteristic of the oil relative permeability scanning curves is their reversibility; along most of the length of a scanning curve, oil relative permeability exhibits no hysteresis. A proposed mechanism for the reversible behavior is pinning of water-oil interfaces on surfaces of rock grains. Pinned interfaces remain anchored at fixed positions on grains despite changes in interface curvature and contact angle. In water-wet samples, pinning can occur as a result of contact angle hysteresis. In mixed-wet rock, pinning can occur at the boundaries between water-wet and oil-wet grain surfaces. As long as interfaces remain pinned, pore-level fluid geometry is a function of saturation only, and does not depend on the direction of saturation change. Introduction Relative permeability curves, which characterize simultaneous multi-phase flow in porous rock, are important in understanding and predicting the performance of immiscible displacement processes in oil and gas reservoirs. Hysteresis in both relative permeability and contact angle has long been recognized. In the case of relative permeability, two-phase flow properties of a porous medium depend on which phase is increasing in saturation, For contact angle, measured values depend on which phase is advancing over a solid surface, Numerous studies have reported hysteresis data for either relative permeability or contact angle, but little work has been done to link the two phenomena. This paper attempts to make such a linkage by showing that relative permeability data exhibit a hysteresis pattern that would be expected if fluid geometries are controlled by contact angle hysteresis. For the two water-oil systems investigated here, relative permeability scanning curves, which describe flow when the direction of saturation change is reversed, are shown to be reversible over limited saturation ranges. Under these conditions, we propose that contact angles will change between maximum and minimum values while water-oil interfaces remain pinned at fixed positions on grain surfaces. As long as the interfaces remain pinned, changes in fluid geometry are reversible. Outside the range of reversibility, contact angles are at their limiting values, interfaces move along grain surfaces, and fluid geometries are controlled by processes that result in hysteresis. Terminology Processes in porous media that involve decreases in the saturation of the wetting phase are commonly referred to as "drainage". We use that term here to refer to decreases in water saturation for a water-oil system regardless of rock wettability. "Primary drainage" relative permeability curves are those measured while decreasing the water saturation from 100%, while "secondary drainage" curves involve a decrease from the high water saturation occurring when immobile oil is present.

No abstract

Land use change in rangeland ecosystems is pervasive throughout the western United States with widespread ecological, social and economic implications. In California, rangeland habitats have high biodiversity value, provide significant habitat connectivity and form the foundation for a number of ecosystem services. To comprehensively assess the conservation status of these habitats, we analyzed the extent and drivers of habitat loss and the degree of protection against future loss across a 13.5 M ha study area in California. We analyzed rangeland conversion between 1984 and 2008 using time series GIS data and classified resulting land uses with aerial imagery. In total, over 195,000 hectares of rangeland habitats were converted during this period. The majority of conversions were to residential and associated commercial development (49% of the area converted), but agricultural intensification was surprisingly extensive and diverse (40% across six categories). Voluntary enrollment in an agricultural tax incentive program provided widespread protection from residential and commercial conversions across 37% of the remaining rangeland habitat extent (7.5 M ha), though this program did not protect rangeland from conversion to more intensive agricultural uses. Additionally, 24% of the remaining rangeland was protected by private conservation organizations or public agencies through land or easement ownership while 38% had no protection status at all. By developing a spatial method to analyze the drivers of loss and patterns of protection, this study demonstrates a novel approach to prioritize conservation strategies and implementation locations to avert habitat conversion. We propose that this approach can be used in other ecosystem types, and can serve as a regional conservation baseline assessment to focus strategies to effect widespread, cost-effective conservation solutions.

Objectives:To analyse the expression of osteoblast differentiation markers and osteoclast activity in the periodontal ligament (PDL) following 2, 4 and 7 days of orthodontic tooth movement (OTM) in an animal model. Setting and Sample Population:Eighteen C57BL/6 wild-type mice. Material and Methods:For the OTM model, orthodontic force was applied to the maxillary right first molar using a closed-coil NiTi spring activated between the molar and incisors. The left side served as the control. Following OTM, the dissected tissues were scanned for micro-computed tomography (micro-CT) analysis and processed for histology. Histological stains included tartrate-resistant acid phosphatase (TRAP) staining for osteoclasts and immunohistochemistry for osteoblast markers alphasmooth muscle actin (α-SMA), osteopontin (OP) and osteocalcin (OC). Results:Micro-CT analysis showed increasing OTM on days 2, 4 and 7 days as well as decrease in bone volume and per cent bone volume at 4 and 7 days. Statistically significant increases in osteoblast marker expression were seen in all groups when compared to the control. TRAP expression was highest at 4 and 7 days, α-SMA was highest at 2 days and OP/OC was highest at 4 days. Conclusion:During OTM, proliferation of pre-osteoblasts peaks at 2 days while mineralization of the osteoid peaks at 4 days. The osteoclast response is delayed.