Smooth Topography Research Articles

Variability of soil water content controlled by evapotranspiration and groundwater–root zone interaction

ABSTRACTThe central moments of soil water content (SWC) variability at the field scale are determined by soil texture, considering both smooth topography and groundwater table position. The characteristics of variability are governed by other soil factors like soil structure, micro relief, preferred water flow paths, root system characteristics, rock content, etc. This paper shows the integral effect of all these hardly quantifiable factors on SWC variability simulated by the processes of evapotranspiration and groundwater–root zone interaction using the HYDRUS ET model. SWC and soil hydraulic characteristics were spatially determined over a 4.5 ha field during two sampling campaigns under different atmospheric and groundwater conditions, and data distributions were compared to SWC distributions provided by mathematical modeling. The entire spring–summer period of 2003 was then examined for changes of SWC spatial variability. It was found that evapotranspiration influences SWC spatial variability only if SWC is under the critical value when wetter parts of the field evaporate more water than drier parts, resulting in smoothed SWC variability. Under wet conditions the spatial variability of SWC increases by drainage, as those parts of the soil with coarser texture drain faster than finer-textured parts.

Evidence for seafloor‐intensified mixing by surface‐generated equatorial waves

AbstractLittle is known about mixing in the abyssal equatorial oceans in spite of its inferred importance for upwelling dense water. Here we present full‐depth microstructure turbulence profiles obtained in the equatorial Pacific that show evidence for intense wind‐generated abyssal mixing. Mixing was intensified over the bottom 700 m where the diffusivity reached 10−3 m2 s−1, of similar intensity to mixing driven by tidal flow over rough topography. However, here the mixing was found over smooth topography. We suggest that the intense mixing could have been driven by surface‐generated equatorial waves through two possible mechanisms: (1) near‐bottom wave trapping as a result of the horizontal component of the Earth's rotation and (2) inertial instability. The generation of lee waves over smooth topography at low latitudes and their subsequent breaking is another viable mechanism for the mixing.

Injectable gellan gum-based nanoparticles-loaded system for the local delivery of vancomycin in osteomyelitis treatment.

Infection spreading in the skeletal system leading to osteomyelitis can be prevented by the prolonged administration of antibiotics in high doses. However systemic antibiotherapy, besides its inconvenience and often low efficacy, provokes numerous side effects. Thus, we formulated a new injectable nanoparticle-loaded system for the local delivery of vancomycin (Vanc) applied in a minimally-invasive way. Vanc was encapsulated in poly(l-lactide-co-glycolide) nanoparticles (NPs) by double-emulsification. The size (258 ± 11 nm), polydispersity index (0.240 ± 0.003) and surface potential (−25.9 ± 0.2 mV) of NPs were determined by dynamic light scattering and capillary electrophoresis measurements. They have a spherical morphology and a smooth topography as observed using atomic force microscopy. Vanc loading and encapsulation efficiencies were 8.8 ± 0.1 and 55.2 ± 0.5 %, respectively, based on fluorescence spectroscopy assays. In order to ensure injectability, NPs were suspended in gellan gum and cross-linked with Ca2+; also a portion of dissolved antibiotic was added to the system. The resulting system was found to be injectable (extrusion force 11.3 ± 1.1 N), reassembled its structure after breaking as shown by rheology tests and ensured required burst release followed by sustained Vanc delivery. The system was cytocompatible with osteoblast-like MG-63 cells (no significant impact on cells’ viability was detected). Growth of Staphylococcus spp. reference strains and also those isolated from osteomyelitic joints was inhibited in contact with the injectable system. As a result we obtained a biocompatible system displaying ease of application (low extrusion force), self-healing ability after disruption, adjustable drug release and antimicrobial properties.

RhoA-Mediated Functions in C3H10T1/2 Osteoprogenitors Are Substrate Topography Dependent.

Surface topography broadly influences cellular responses. Adherent cell activities are regulated, in part, by RhoA, a member of the Rho-family of GTPases. In this study, we evaluated the influence of surface topography on RhoA activity and associated cellular functions. The murine mesenchymal stem cell line C3H10T1/2 cells (osteoprogenitor cells) were cultured on titanium substrates with smooth topography (S), microtopography (M), and nanotopography (N) to evaluate the effect of surface topography on RhoA-mediated functions (cell spreading, adhesion, migration, and osteogenic differentiation). The influence of RhoA activity in the context of surface topography was also elucidated using RhoA pharmacologic inhibitor. Following adhesion, M and N adherent cells developed multiple projections, while S adherent cells had flattened and widespread morphology. RhoA inhibitor induced remarkable longer and thinner cytoplasmic projections on all surfaces. Cell adhesion and osteogenic differentiation was topography dependent with S < M and N surfaces. RhoA inhibition increased adhesion on S and M surfaces, but not N surfaces. Cell migration in a wound healing assay was greater on S versus M versus N surfaces and RhoA inhibitor increased S adherent cell migration, but not N adherent cell migration. RhoA inhibitor enhanced osteogenic differentiation in S adherent cells, but not M or N adherent cells. RhoA activity was surface topography roughness dependent (S < M, N). RhoA activity and -mediated functions are influenced by surface topography. Smooth surface adherent cells appear highly sensitive to RhoA function, while nano-scale topography adherent cell may utilize alternative cellular signaling pathway(s) to influence adherent cellular functions regardless of RhoA activity.

Thermally Stable Silver Nanowire–Polyimide Transparent Electrode Based on Atomic Layer Deposition of Zinc Oxide on Silver Nanowires

The performance of a flexible transparent conductive electrode with extremely smooth topography capable of withstanding thermal processing at 300 °C for at least 6 h with little change in sheet resistance and optical clarity is reported. In depth investigation is performed on atomic layer deposition (ALD) deposited ZnO on Ag nanowires (NWs) with regard to thermal and atmospheric corrosion stability. The ZnO coated nanowire networks are embedded within the surface of a polyimide matrix, and the &lt;2 nm roughness freestanding ­electrode is used to fabricate a white polymer light emitting diode (PLED). PLEDs obtained using the ZnO‐AgNW‐polyimide substrate exhibit comparable performance to indium tin oxide (ITO)/glass based devices, verifying its efficacy for use in optoelectronic devices requiring high processing temperatures.

Origen y funcionamiento hidrogeológico del único criptohumedal subhalófilo-alcalinófilo en la facies Guadalajara del acuífero Terciario detrítico de Madrid

Dehesa de Arriba wetland is a subhalofite-alkalinofite reed meadow so far not described among the Madrid tertiary aquifer wetlands. Is located in the medium-high area of Henares river tertiary basin. The evaporation phenomena are the reason of its diversity and the presence of alkaline efflorescence. The water in origin is the discharge of small evolve groundwater, of the type HCO 3 -Ca and mineralization of 700 μS/cm, 2 km southward from the point where Camarmilla is captured by Torote river. The morphology of the wetland play an important role in the distribution of the species and the alkaline efflorescence since determine the phreatic level depth and affects the extent of capillary water up to the surface. The drainage of the soils in scarce because the smooth topography and the small erosion of the river after its capture. To the wetland, that is now the born of the Camarmilla stream, arrives 56.400 m 3 of groundwater annually and its soils generate a surplus of 29.000 m 3 from december to may in average years. The alkalinity is high in any area, although is higher in the graminoids and cyperaceous zones and is the highest in the efflorescence with a pH of 10.3 and a concentration of Na+ in its solution of 2871 mg/l. No significant difference of these parameters have been found between the soils where juncus acutus is located and other juncacea soils. The formation processes of this wetland and its high plants diversity make it singular in the Madrid aquifer context and constitute a unique enclave in Castilla-La Mancha.

Effect of surface topography upon micro-impact dynamics

Often the effect of interactions at nano-scale determines the tribological performance of load bearing contacts. This is particularly the case for lightly loaded conjunctions where a plethora of short range kinetic interactions occur. It is also true of larger load bearing conjunctions where boundary interactions become dominant. At the diminutive scale of fairly smooth surface topography the cumulative discrete interactions give rise to the dominance of boundary effects rather than the bulk micro-scale phenomena, based on continuum mechanics. The integration of the manifold localized discrete interactions into a continuum is the pre-requisite to the understanding of characteristic boundary effects, which transcend the physical length scales and affect the key observed system attributes. These are energy efficiency and vibration refinement. This paper strives to present such an approach. It is shown that boundary and near boundary interactions can be adequately described by surface topographical measures, as well the thermodynamic conditions.

In vitro analysis of a novel controlled release system designed for intratympanic administration of N-acetylcysteine: a preliminary report

The aim of this in-vitro experimental study was to design a novel drug delivery system that may permit controlled release of N-acetylcysteine (NAC) following intratympanic administration. The system was composed of two different solutions that attained a hydrogel form within seconds after getting into contact with each other. The authors performed swelling, pH and temperature tests and analysis of controlled release of NAC from this novel controlled release system. For the structure and porosity analysis of the hydrogel, an environmental scanning electron microscope (SEM) was used. The diameter of designed hydrogel showed an increase when pH was increased. In addition, in comparison to acidic values, the pore diameter of the hydrogel increased significantly especially in physiological level. The increase in the pore diameter was also directly proportional to the increase in temperature. Spectrophotometric analysis showed that the amount of NAC released into the medium was statistically significant (p=0.038, t=−2.18, 95% CI; DF: 27). SEM analysis of the samples revealed a smooth surface topography and numerous porous structures. The authors are of the opinion that the designed hydrogel may be used as an alternative method for intratympanic delivery of NAC for otoprotective purposes. The disadvantages of intratympanic injection of the drug in its liquid form, including leakage through eustachian tube, restraining the patient in an uncomfortable position, necessity for repetitive injections and dose dependent inflammation of the middle ear epithelium, may also be avoided. Further in vivo studies should be conducted to assess its tolerability and effectivity.

Characterization of GaN/p-Si solar cell prepared by simple technique

This study involves the synthesis of nanostructure GaN films on glass and Si substrates prepared by high vacuum thermal evaporation technique. Atomic force microscopy measurements reveal that the sample was found to have a smooth surface topography. X-ray diffraction showed high-quality GaN epilayer with a hexagonal shape. The optical properties were studied using micro-photoluminescence and UV–vis spectrophotometer. Micro-photoluminescence spectra displayed intensity enhancement with blue-shifted band-edge PL peaks associated with the increasing annealing temperature. The blue shifted in absorbencies spectroscopy for GaN films further confirms such behavior. The capacitance–voltage characteristics were measured, and it is found within the range of (Vbi=0.86–1.4V). I–V characteristic of GaN/Si (p-type) heterojunction are investigated. It is found that the maximum efficiency is (4.8) at annealing temperature Ta=373K while at Ta=573K is (8.8).

Macrobenthos of the southern part of St. Anna trough and the adjacent Kara Sea shelf

Taxonomic composition and ecological structure of benthic communities of the southern part of St. Anna Trough were investigated during the 54th and 59th cruises of RV Akademik Mstislav Keldysh. Material was collected using Sigsbee trawl at 10 stations arranged in two transects (depth range 57–554 m). It was shown that benthic communities of the western arm of the St. Anna Trough differ considerably from the communities of the eastern arm. The western arm communities develop under the influence of active near-bottom hydrodynamics in conditions of rugged topography and a coarse-grained sediment or hard substrate. The wastern arm of the trough is characterized by the predomination of the soft sediment, smooth topography, and weak currents. In the western arm of the trough the influence of the Barents Sea fauna is traced down to the edge of the internal shelf (about 150 m depth). The community of the eastern arm of the trough situated out from the direct influence of the Barents Sea waters represents a continuation of the Ophiocten sericeum community, typical for external Kara Sea shelf. With increasing depth, Ophiopleura borealis becomes the dominant species of the community. In the greatest explored depths some deep-water High-Arctic species, such as echinoids Pourtalesia jeffreysi, were observed. The major factors determining the distribution of benthic communities in the investigated area are the microrelief pattern, the sediment structure, and near-bottom hydrodynamics.

Multi‐block finite‐difference method for 3D elastodynamic simulations in anisotropic subhorizontally layered media

ABSTRACTPrediction of elastic full wavefields is required for reverse time migration, full waveform inversion, borehole seismology, seismic modelling, etc. We propose a novel algorithm to solve the Navier wave equation, which is based on multi‐block methodology for high‐order finite‐difference schemes on curvilinear grids. In the current implementation, the blocks are subhorizontal layers. Smooth anisotropic heterogeneous media in each layer can have strong discontinuities at the interfaces. A curvilinear adaptive hexahedral grid in blocks is generated by mapping the original 3D physical domain onto a parametric cube with horizontal layers and interfaces. These interfaces correspond to the main curvilinear physical contrast interfaces of a subhorizontally layered formation. The top boundary of the parametric cube handles the land surface with smooth topography. Free‐surface and solid–solid transmission boundary conditions at interfaces are approximated with the second‐order accuracy. Smooth media in the layers are approximated up to sixth‐order spatial schemes. All expected properties of the developed algorithm are demonstrated in numerical tests using corresponding parallel message passing interface code.

Microspheres Embedded In Microbeads: A Novel Approach to Improve Various Controlled Release Characteristics of Highly Water Soluble Drug through Ionic Gelation Method

Abstract: The major hindrance behind the preparation of gellan microbeads by simple ionic gelation technique with aqueous soluble drugs is their low entrapment efficiency and sometimes its faster dissolution characteristics. This limits the employment of such a simple method for the preparation of microbeads of water-soluble drugs like stavudine. In the present study a novel attempt has been undertaken by embedding stavudine loaded Eudragit RSPO microspheres into gellan microbeads by ionotropic gelation method with an aim to improve its controlled drug delivery characteristics. The prepared microbeads were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and optical microscopy for surface topography, drug polymer interaction and particle size analysis respectively. Other studies like drug content, encapsulation efficiency and drug release studies were also carried out. The resulting microspheres embedded in microbeads were free flowing in nature with mean particle size ranging from 544.2-564.2 μm. SEM photomicrographs distinctly shows the microspheres embedded within the microbeads effectively with a smooth surface topography and the gellan microbeads containing D4T only are spherical in nature with rough surface. The FTIR study ascertained the compatibility of the drug within the formulation. The microspheres embedded in microbeads had enhanced percentage of drug content, drug entrapment efficiency and controlled release characteristics as compared to beads containing stavudine only. The mechanism of drug release from the formulations were found to follow non Fickian type diffusion with “n” value between 0.5 to 1but in case of stavudine loaded Eudragit RSPO microspheresit was found to be Fickian type. Key words: Gellan gum, Stavudine, Microbeads, Microsphere embedded in Microbeads, Entrapment efficiency, and Controlled release.

AUV Terrain-Aided Navigation using a Doppler Velocity Logger

The potential of terrain-aided navigation (TAN) of autonomous underwater vehicles (AUVs) has been demonstrated in the last ten years in a series of trials where high localization accuracy was obtained during long periods of time in different types of terrain. Despite these recent advances, it is recognized by the navigation community that further research is necessary to transform TAN into a mature navigation methodology. The present paper describes the work developed towards the development of terrain navigation methods for small AUVs, relying on standard navigation sensors and dispensing with the need of dedicated sensors for terrain data acquisition. The research described addresses the problem of implementation of terrain navigation in underwater scenarios characterized by smooth sea-bottom topography and very shallow water, where the terrain information available for navigation is scarce. The TAN algorithms and the data fusion methods whose tests are documented in the paper build upon prior theoretical work published by the authors. The experimental results reported were obtained recently through trials in the water performed with an autonomous surface vehicle acting as a proxy to an AUV.

Asymptotic shallow water models with non smooth topographies

We present new models to describe shallow water flows over non smooth topographies. The water waves problem is formulated as a system of two equations on surface quantities in which the topography is involved in a Dirichlet-Neumann operator. Starting from this formulation and using the joint analyticity of this operator with respect to the surface and the bottom parametrizations, we derive a nonlocal shallow water model which only includes smoothing contributions of the bottom. Under additional small amplitude assumptions, Boussinesq-type systems are also derived. Using these alternative shallow water models as references, we finally present numerical tests to assess the precision of the classical shallow water approximations over rough bottoms. In the case of a polygonal bottom, we show numerically that our new model is consistent with the approach developed by Nachbin.

The effect of surface treatment and topography on corrosion behavior of EN 1.4404 stainless steel

Corrosion properties of EN 1.4404 (316L) stainless steel with different applied surface treatment, were studied in NaCl solution using cyclic polarization. Observed properties were related to the specific topography of each surface by scanning electron microcopy and cross‐section analysis. Average roughness was measured to evaluate the usability for this parameter to be used in assessment of corrosion resistance. Increased surface roughness and the existence of crevices resulted in overall deterioration of corrosion resistance, whereas more smooth and level topographies displayed general improvement. By analyzing the characteristic geometry of the typographies produced, the correlation between the varying corrosion properties and surfaces is determinable. In continuation hereof, the utilization of average roughness values (Ra) as an isolated parameter, were found not to be sufficient for the assessment of corrosion resistance. Critical surface geometries with large impact on corrosion properties is not conveyed adequately by Ra, and thereby prevents sufficient differentiation between the actual surface properties.

New insights on the Salmon Falls Creek Canyon landslide complex based on geomorphological analysis and multitemporal satellite InSAR techniques

Multitemporal satellite interferometric synthetic aperture radar (InSAR) techniques can characterize line-of-sight displacements of active landslide areas with resolution (mm scale) and accuracy comparable to or higher than differential GPS, sensor network, or photogrammetry techniques. This study improves understanding of the rate of movement and the lateral extent of the active domain of a landslide complex within Salmon Falls Creek Canyon near Twin Falls, Idaho. Specifically, we were able to estimate displacement of yearly motion rates in early and late stages of the event by analyzing a collection of archived radar satellite imagery. Small baseline subset (SBAS) InSAR performed better than persistent scatterer (PS) InSAR for analyzing distributed scatterers because of its ability to capture strongly nonlinear displacement rates. In addition, comparison with GPS field measurements showed agreement with InSAR-derived displacements. Geostatistical analysis was used to describe surface and morphometric characteristics of two separate landslides within Salmon Falls Creek Canyon. Each was divided into representative geomorphologic units, and morphometric analysis focused on two key parameters: topographic texture and mean slope. Scarp units are topographically rough because of their greater relief and steep slopes, while a displaced headwall block has retained a smooth topography. Each landslide upper body has a higher topographic texture than the corresponding body unit. Both landslides display a progressive decrease in mean slope from upper body to toe to body. InSAR SBAS results showed that headwall block and transverse scarp of the landslide complex at Salmon Falls Creek Canyon had the highest mean annual velocity in the radar line-of-sight (LOS) direction. Velocity of movement in each landslide toe and body was less, signifying that LOS movement was more active in the upper reaches of the landslides, although lateral translation may have been greater in the body and toe compared to the headwall region due to the curved shape of the landside detachment surface.

Fabrication of Cu(In,Al)(S,Se)2 films by sulfurization and selenization of co-sputtered Cu-In-Al precursors

Cu(In,Al)(S,Se)2 (CIASSe) films were prepared on soda lime glass substrates by sulfuring and selenizing co-sputtered Cu-In-Al metal precursors. CIASSe film preparation was optimized and the film properties were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, and ultraviolet–visible spectroscopy. Films that were annealed for 20min formed a single-phase chalcopyrite structure, and those films annealed at 500°C and 540°C exhibited a smooth and dense surface topography. After being annealed at 450–540°C, films contained reduced amounts of copper and close to ideal stoichiometric compositions. Their absorption coefficients were over 104cm−1, and the obtained optical band gap values were 1.37eV, 1.42eV, and 1.44eV, respectively, which were close to the ideal optical band gaps for photovoltaic applications.

Flexible transparent conducting hybrid film using a surface-embedded copper nanowire network: a highly oxidation-resistant copper nanowire electrode for flexible optoelectronics.

We report a flexible high-performance conducting film using an embedded copper nanowire transparent conducting electrode; this material can be used as a transparent electrode platform for typical flexible optoelectronic devices. The monolithic composite structure of our transparent conducting film enables simultaneously an outstanding oxidation stability of the copper nanowire network (14 d at 80 °C), an exceptionally smooth surface topography (R(rms) < 2 nm), and an excellent opto-electrical performances (Rsh = 25 Ω sq(-1) and T = 82%). A flexible organic light emitting diode device is fabricated on the transparent conducting film to demonstrate its potential as a flexible copper nanowire electrode platform.

Laser polishing of niobium for superconducting radio-frequency accelerator applications

Interior surfaces of niobium cavities used in superconducting radio frequency accelerators are now obtained by buffered chemical polish and/or electropolish. Laser polishing is a potential alternative, having advantages of speed, freedom from noxious chemistry and availability of in-process inspection. We studied the influence of the laser power density and laser beam raster rate on the surface topography. These two factors need to be combined carefully to smooth the surface without damage. Computational modeling was used to estimate the surface temperature and gain insight into the mechanism of laser polishing. Power spectral density analysis of surface topography measurements shows that laser polishing can produce smooth topography similar to that obtained by electropolish. This is a necessary first step toward introducing laser polishing as an alternative to the currently practiced chemical polishing.

Fluorinated polyimide gate dielectrics for the advancing the electrical stability of organic field-effect transistors.

Organic field-effect transistors (OFETs) that operated with good electrical stability were prepared by synthesizing fluorinated polyimide (PI) gate dielectrics based on 6FDA-PDA-PDA PI and 6FDA-CF3Bz-PDA PI. 6FDA-PDA-PDA PI and 6FDA-CF3Bz-PDA PI contain 6 and 18 fluorine atoms per repeat unit, respectively. These fluorinated polymers provided smooth surface topographies and surface energies that decreased as the number of fluorine atoms in the polymer backbone increased. These properties led to a better crystalline morphology in the semiconductor film grown over their surfaces. The number of fluorine atoms in the PI backbone increased, the field-effect mobility improved, and the threshold voltage shifted toward positive values (from -0.38 to +2.21 V) in the OFETs with pentacene and triethylsilylethynyl anthradithiophene. In addition, the highly fluorinated polyimide dielectric showed negligible hysteresis and a notable gate bias stability under both a N2 environment and ambient air.