This study utilizes speleothem trace elements as climate proxies to reconstruct hydroclimate variability over approximately 350 years in the Southern Cook Islands. Stalagmites Pu17 and Pu4 from Pouatea cave were analyzed using high-resolution LA-ICP-MS for trace elements (Mg, Na, Sr, P, U, Y). By monitoring cave dripwater and conducting regression analysis, we found that Mg, Sr, and Na in Pouatea dripwater mostly originated from marine aerosols, while Sr and Ba were primarily from bedrock, with additional Ba coming from marine aerosols and weathered oceanic basalt leaching. Mg was identified as the most reliable element for hydroclimate reconstruction due to its predominantly marine aerosol origin. Infiltration, via dilution of marine aerosols and bedrock inputs, was identified as the main driver of trace element variations in Pouatea at a seasonal scale. Transfer functions were established between each trace element and effective infiltration was calculated, with Mg showing the strongest correlation. The reconstructed infiltration data were compared with climate indices, showing an overarching role of the SPCZ and ENSO in controlling rainfall in the South Pacific. This research demonstrates the potential of speleothem trace elements for paleohydroclimate reconstructions, improving understanding of rainfall variability in the climatically vulnerable South Pacific Islands over the past millennia.

On low-input smallholder farms of Kenyan upland landscapes, erosion of nutrient-rich topsoil strongly affects crop yields. Where maize (Zea mays) is intercropped on erosion-prone slopes, intercropping can potentially reduce soil erosion. The objective of this research was to quantify the contribution of crops and crop mixtures of different growth habits to erosion control and their influence on above-ground biomass and earthworm abundance as indicators of soil function in smallholder farming systems under a bimodal rainfall pattern in Western Kenya. The experiment involved five treatments, namely maize (Z. mays)/common bean (Phaseolus vulgaris) intercrop (maize intercrop), maize/common bean intercrop plus Calliandra (Calliandra calothyrsus) hedgerows and Calliandra mulch (Calliandra), sole Lablab (Lablab purpureus), sole Mucuna (Mucuna pruriens) and groundnut (Arachis hypogaea) intercropped with maize (during the short rains). The experiment was conducted over three consecutive cropping seasons and the cropping system had significant effects on soil loss, runoff, water infiltration, earthworm abundance and above-ground biomass and crop grain yield. The Calliandra treatment had the lowest runoff (11.6–17.2 mm ha−1) and soil erosion (31–446 kg ha−1 per season) in all the seasons, followed by the Mucuna treatment. Lablab was affected by disease and showed the highest soil erosion in the last two seasons. Infiltration was highest in Calliandra treatment, and earthworm abundance was higher under Mucuna and Calliandra treatments (229 and 165 earthworms per square metre, respectively) than under other crops. Our results suggest that including sole crops of herbaceous species such as Mucuna, or tree hedgerows with mixtures of maize and grain legumes has the potential to reduce runoff and soil erosion in smallholder farming. Additionally, these species provide a suitable habitat for earthworms which stabilise soil structure and macropores and thus potentially increase infiltration, further reducing soil erosion.

Although the effectiveness of vegetative filter strips (VFS) for reducing herbicide runoff is well documented, a comprehensive review of the literature does not exist. The objectives of this article are to denote the methods developed for evaluating herbicide retention in VFS; ascertain the efficacy of VFS regarding abating herbicide runoff; identify parameters that affect herbicide retention in VFS; review the environmental fate of herbicides retained by VFS; and identify future research needs. The retention of herbicide runoff by VFS has been evaluated in natural rainfall, simulated rainfall, and simulated run-on experiments. Parameters affecting herbicide retention in VFS include width of VFS, area ratio, species established in the VFS, time after establishment of the VFS, antecedent moisture content, nominal herbicide inflow concentration, and herbicide properties. Generally, subsequent transport of herbicides retained by VFS is reduced relative to adjacent cultivated soil because of enhanced sorption and degradation in the former.

The quantitative effect of the following parameters on the one single step pressureless infiltration characteristics of bilayer B4Cp/rice-husk ash (RHA) porous preforms by aluminum alloys was investigated using the Taguchi method and analysis of variance (ANOVA): infiltration temperature and time, B4C particle size, RHA percentage, percentage porosity in the preforms, and magnesium content in the alloy. The contributions of each of the parameters to the retained porosity, hardness and modulus of elasticity of the resulting bilayer composites were determined. The parameters that most significantly impact the modulus of elasticity (E) of the resulting composites are chemical composition of Al alloy followed by porosity of preforms and B4C particle size. Their relative contributions to the variance in the values of modulus of elasticity are 25.7, 22.48 and 18.44 %, respectively. Verification tests conducted using the established optimum parameters show a good agreement with those of projected values.

Molten deposits based on calcium-magnesium alumino-silicates (CMAS), originating from siliceous debris ingested with the intake air, represent a fundamental threat to progress in gas turbine technology by limiting the operating surface temperature of coated components. The thermomechanical and thermochemical aspects of the CMAS interactions with thermal-barrier coatings, as well as the current status of mitigating strategies, are discussed in this article. Key challenges and research needs for developing adequate solutions are highlighted.

Conservation agriculture (CA) systems are based upon minimal soil disturbance; crop residue retention and crop rotation and/or intercrop association are increasingly seen to recycle nutrients, increase yield and reduce production costs. This study examines the effects of CA practices on crop productivity, profitability and soil quality under the conditions encountered by smallholder farmers in two farming communities from 2005 to 2011 in Malawi, as part of the contribution to remedy a lack of supporting agronomic research for these relatively new systems. The drier agroenvironment of Lemu of Bazale Extension Planning Area (EPA) is characterized by sandy clay loam soils and lower rainfall. Here, CA showed positive benefits on maize yield after the first season of experimentation, with highest increases of 2.7 Mg ha−1 and 2.3 Mg ha−1 more yield in CA monocrop maize and CA maize–legume intercrop, respectively, than the conventional tillage in the driest season of 2009/10. In the high rainfall environment of Zidyana EPA (characterized by sandy loam soils), substantial maize yield benefits resulted in the fifth season of experimentation. Farmers spent at most 50 days ha−1 (US$140) producing maize under CA systems compared with 62 days ha−1(US$176) spent under conventional tillage practices. In Lemu, both CA systems resulted in gross margins three times higher than that of the conventional control plot, while in Zidyana, CA monocrop maize and CA maize–legume intercrop resulted in 33 and 23% higher gross margins, respectively, than conventional tillage. In Zidyana, the earthworm population was highest (48 earthworms m−2 in the first 30 cm) in CA monocrop maize, followed by a CA maize–legume intercropping (40 earthworms) and lowest (nine earthworms) in conventionally tilled treatment. In both study locations CA monocrop maize and CA maize–legume intercrop gave higher water infiltration than the conventional treatment. Improvements in crop productivity, overall economic gain and soil quality have made CA an attractive system for farmers in Malawi and other areas with similar conditions. However, for extensive adoption of CA by smallholder farmers, cultural beliefs that crop production is possible without the ubiquitous ridge and furrow system and residue burning for mice hunting have to be overcome.

Si–SiC composite (reaction bonded SiC) with a submicron SiC microstructure (starting SiC particle size: 0.22 μm) was examined by XRD analysis to determine the amount and phase composition of the secondary SiC formed by the reaction between silicon and carbon during the sintering process. It was found that the secondary SiC has grown onto the original hexagonal α-SiC grains as well as into the porosity of the green body. An increase of 3C–SiC was found within the microstructure after infiltration (from 2.6 wt. % before infiltration to 8.8 wt. % after infiltration) whereas the 4H-ploytype content was reduced. This behavior may be explained by the very small original SiC grains which acted as seeds for disoriented SiC growth and were assumed to force the nonepitaxically deposition of secondary SiC. Solid state and fast transportation processes caused the observed transformation of the SiC. Examinations of the silicon source (infiltrant) after the infiltration procedure showed that most of the carbon was converted to SiC with cubic modification (3C stacking sequence)

Atomic layer deposition (ALD) uses self-limiting chemical reactions between gaseous precursors and a solid surface to deposit materials in a layer-by-layer fashion. This process results in a unique combination of attributes, including sub-nm precision, the capability to engineer surfaces and interfaces, and unparalleled conformality over high-aspect ratio and nanoporous structures. Given these capabilities, ALD could play a central role in achieving the technological advances necessary to redirect our economy from fossil-based energy to clean, renewable energy. This article will survey some of the recent work applying ALD to clean energy conversion, utilization, and storage, including research in solid oxide fuel cells, thin-film photovoltaics, lithium-ion batteries, and heterogenous catalysts. Throughout the manuscript, we will emphasize how the unique qualities of ALD can enhance device performance and enable radical new designs.

The thermal recoverability of a nanoporous silica-based system modified by a cross-linked polyelectrolyte is investigated. At room temperature, as a nominally hydrostatic pressure is applied, the gel matrix can be partially dehydrated. The released water molecules will be forced into the initially energetically unfavorable nanopores and are “locked” there. At an elevated temperature, the infiltration pressure increases slightly, which is contradictory to the experimental data of the unmodified system. More importantly, the defiltration of the confined liquid is significantly promoted, leading to a much higher system recoverability.

We explored the possibility of incorporating carbon nanotubes in a patterned and macroporous silica structure replicated from a thin polystyrene template. A V-shaped thin, vertical channel was constructed and successfully used to assemble 10.06-μm polystyrene spheres into a dense three-dimensionally ordered template of uniform thickness. Infiltration of a single Co/silica precursor sol into the template followed by thermal treatments in vacuum and H2 produced three-dimensionally ordered silica pores with embedded Co nanoparticles. Wormlike carbon nanofilaments of 50–120 nm in diameter were grown on the inner surface of silica pores with plasma-enhanced chemical vapor deposition.

Raw and partially infiltrated carbon–carbon composite preforms have been scanned by high-resolution synchrotron radiation x-ray computerized micro-tomography. Three dimensional high-quality images of the pore space have been produced at two distinct resolutions and have been used for the computation of geometrical quantities: porosity, internal surface area, pore sizes, and their distributions, as well as local and average fiber directions. Determination of the latter property makes use of an original algorithm. All quantities have been compared to experimental data with good results. Structural models appropriate for ideal families of cylinders are shown to represent adequately the actual pore space.

A thin-frame nano-network film of titania with backbone diameter of 20–30 nm was obtained from precursor templating of nano-porous polymer with nano-channels 50 nm in width. The nano-porous polymer templates were prepared by selective removal of the polyisoprene (PI) domain with ozone from the bicontinuous structure formed through blending a symmetric polystyrene-block-polyisoprene (PS-b-PI) copolymer with a PS homopolymer (h-PS). The titania network possessed the preferred anatase crystallinity for photocatalytic applications and a specific surface area of 53 m2/g, comparable to that of Degussa P25, a widely used commercial photocatalyst. Photocatalytic performance of the fractured titania network film was also comparable to that of Degussa P25 in both gas-phase NO oxidation and liquid phase methylene blue degradation. The much larger overall structure size of the fractured titania network film, however, offers advantages over the nano-particulate form of P25, namely, easy handling and rapid recycling from treated streams.

The energy absorption behaviors of mesoporous silica particles immersed in aqueous solutions of ethanol were investigated. Addition of ethanol could significantly lower the infiltration pressure, which has great potential in developing selective protection systems. The ethanol concentration of the confined liquid inside the nanopores was higher than outside.

The stable mechanical property polystyrene (PS) nanotubes with array structure were first prepared by filtrating a solution or melt of normal molecular weight PS (Mn ≈ 180,000) into anodic aluminum oxide (AAO) template with only 200-nm pores. The results of transmission electron microscopy and scanning electron microscopy illuminated that PS tubules were successfully obtained and the wall thickness of PS tubules prepared by the 2.5 wt%, 5.0 wt%, and 10.0 wt% PS solution were respectively 50 nm, 70 nm, and 80 nm. The structure of polymer nanotubes depends strongly on the concentration of PS solution. It was found that the wall of the nanotubes derived from melt is thicker than that of the nanotubes from solution. When the polymer solution wets AAO template, a thin polymer film will be formed on the inner porous wall. The thin film/AAO composite membrane acts as a “second-order” template and is soaked repeatedly. So PS solution wets the template and forms nanotubes according to the multi-time wetting mechanism.

Dense, polycrystalline MgO was infiltrated with monticellite (CaMgSiO4) liquid to study the penetration of liquid along the grain boundaries of MgO. Grain growth was found to be restricted with increasing amounts of liquid. The inter-granular regions were generally found to be comprised of a two-phase mixture: crystalline monticellite and a glassy phase rich in the impurities present in the starting MgO material. MgO grains act as seeding agents for the crystallization of monticellite. The location and composition of the glassy phase with respect to the MgO grains emphasizes the role of intergranular liquid during the devitrification process in “snowplowing” impurities present in the matrix.

The formation of crusts or seals at the soil surface is exceedingly important in determining how much rainfall infiltrates into the soil and how much runs off, causing soil erosion. This paper explores the processes involved in the formation of crusts, such as raindrop impact and clay dispersion, to formulate a picture of the mechanisms involved. We discuss the major consequences of crusting, namely, runoff, erosion, and impaired seedling emergence, and present strategies to reduce soil degradation. Examples are offered from many parts of the world.