Size Of Ridges Research Articles

Morphology of transverse aeolian ridges (TARs) on Mars from a large sample: Further evidence of a megaripple origin?

Using HiRISE digital terrain models (DTMs), we developed a large morphological dataset to examine the three-dimensional shape, size, and scaling of Martian transverse aeolian ridges (TARs). Considerable debate exists on the characteristic morphology of TARs and the origins of these enigmatic bedforms. Some researchers suggest polygenesis or multiple classes of similar bedforms. Reliably characterizing the morphology of TARs is an essential prerequisite to developing and evaluating process-based models of TAR genesis and unraveling aeolian processes on the surface of Mars. We present measurements of TAR morphology from a large, DTM-derived dataset (n = 2295). We focused on TARs with ‘simple’ morphologies in order enable more defensible discretization. Histograms and cumulative log-frequency plots of morphometric parameters (length, width, height, elongation ratio, and wavelength) indicate the sample represents a continuum of bedforms from a single population. A typical TAR from our dataset is 88.5m long (longest planview axis), 17.3m wide (shortest planview axis), 1.3m tall, and has a wavelength of 25.8m. Combined with these data, the bulk of evidence presented to date suggests that interpreting TARs as megaripples is the most viable working hypothesis.

Avulsion flow-path selection on rivers in foreland basins

Abstract River avulsions help distribute sediment across the floodplain, and the frequency and flow path selected by each avulsion determines flooding and sedimentation patterns. However, rivers avulse infrequently, making it difficult to quantify flow-path behavior and test hypotheses posed by experimental and numerical studies. We used Google Earth Engine to create a novel data set of 55 avulsions that occurred from A.D. 1984 to 2014 in the Andean and Himalayan foreland basins. On each avulsion we measure hop length (the displacement of the avulsion across the floodplain orthogonal to the parent channel) and avulsion length (the length of the parent channel reach). Without controlling for external factors, such as climate or geology, we find that both hop length and avulsion length scale with parent channel-belt width. Avulsion channels tend to hop 2.5 channel-belt widths away from their parent channel and avulsion length is 13.4 parent channel-belt widths. We use these data to test between end-member scenarios where flow paths are randomly selected or steered by floodplain topography. Observed avulsions are inconsistent with flow-path predictions derived from a directed random walk model, and a scaling analysis of alluvial ridge size shows that hop lengths are set by alluvial ridge widths. These results suggest that avulsion flow-path selection in the Andean and Himalayan basins is driven by alluvial ridge topography, which promotes evenly spaced (or compensational) channel sand bodies over decadal time scales. These data and results are important for understanding controls on avulsion flow-path selection and how avulsion processes are represented in the stratigraphic record of foreland basins.

III/V nano ridge structures for optical applications on patterned 300 mm silicon substrate

We report on an integration approach of III/V nano ridges on patterned silicon (Si) wafers by metal organic vapor phase epitaxy (MOVPE). Trenches of different widths (≤500 nm) were processed in a silicon oxide (SiO2) layer on top of a 300 mm (001) Si substrate. The MOVPE growth conditions were chosen in a way to guarantee an efficient defect trapping within narrow trenches and to form a box shaped ridge with increased III/V volume when growing out of the trench. Compressively strained InGaAs/GaAs multi-quantum wells with 19% indium were deposited on top of the fully relaxed GaAs ridges as an active material for optical applications. Transmission electron microcopy investigation shows that very flat quantum well (QW) interfaces were realized. A clear defect trapping inside the trenches is observed whereas the ridge material is free of threading dislocations with only a very low density of planar defects. Pronounced QW photoluminescence (PL) is detected from different ridge sizes at room temperature. The potential of these III/V nano ridges for laser integration on Si substrates is emphasized by the achieved ridge volume which could enable wave guidance and by the high crystal quality in line with the distinct PL.

A Radially Organized Multipatterned Device as a Diagnostic Tool for the Screening of Topographies in Tissue Engineering Biomaterials.

Micro- and nanotextured biomaterial surfaces have been widely studied for their capacity to drive the regeneration of organized tissues. Nanotopographical features in the shape of groove-ridge patterns aim at mimicking the extracellular matrix organization. However, to date, a wide array of groove and ridge sizes has been described. In this work, we therefore tested a device composed of a multipatterned array consisting of six patterns of radially arranged parallel nanogrooves, with a pitch ranging from 0 to 1000 nm and a depth ranging from 0 to 170 nm, to be used as a tool for the expeditious and simultaneous screening of surface topographies aiming the regeneration of anisotropically organized tissues such as ligament. The topographies were reproduced in (1) epoxy resin or (2) membranes produced by the crosslinking of platelet lysate (PL) with genipin (gPL). Both materials were seeded with periodontal ligament cells (PDLCs) and the proliferation, migration, as well as cell alignment were assessed. The effect of topography in PDLCs was only evident in terms of cell organization, resulting in a highly anisotropic organization of the cells for the 1000 and 600 nm patterns, and in an increased isotropic organization for shallower topographies. Overall, our results suggest that this multipatterned system can be a valuable diagnostic tool for biomaterials aiming at the regeneration of anisotropically organized tissues, such as periodontal ligament.

Human mesenchymal stromal cell-enhanced osteogenic differentiation by contact interaction with polyethylene terephthalate nanogratings

Among the very large number of polymeric materials that have been proposed in the field of orthopedics, polyethylene terephthalate (PET) is one of the most attractive thanks to its flexibility, thermal resistance, mechanical strength and durability. Several studies have been proposed that interface nano- or micro-structured surfaces with mesenchymal stromal cells (MSCs), demonstrating the potential of this technology for promoting osteogenesis. All these studies were carried out on biomaterials other than PET, which remains almost uninvestigated in terms of cell shaping, alignment and differentiation. Here, we study the effect of PET 350-depth nanogratings (NGs) with a ridge and lateral groove size of 500 nm (T1) or 1 μm (T2), on bone marrow-derived human MSC (hMSC) differentiation in relation to the osteogenic fate. We demonstrate that these substrates, especially T2, can promote the osteogenic phenotype more efficiently than standard flat surfaces and that this effect is more marked if cells are cultured in osteogenic medium than in basal medium. Finally, we show that the shape and disposition of calcium hydroxyapatite granules on the different substrates was influenced by the substrate symmetry, being more elongated and spatially organized on NGs than on flat surfaces.

The influence of work roll roughness on the surface/near-surface microstructure evolution of hot rolled aluminum–magnesium alloys

The effect of work roll roughness on the surface/near-surface evolution of aluminum alloys during hot rolling was examined with the use of a rolling tribo-simulator. Work rolls made of steel alloy AISI 52100 with two different surface roughness (Ra) values, 0.1μm and 1.1μm, were used to hot roll Al-Mg alloy samples under similar laboratory conditions for one and ten passes. Surface features on both rolled samples included cracks, grooves, and rolling ridges, but shingles were only observed on the samples rolled with the rougher work roll. Near-surface damage was observed to increase with work roll roughness. Cross-sectional examinations revealed that transverse micro-cracks on the sample rolled with the smoother work roll extended to depths of2.8μm, while cracks were 3.2μm in depth for the rougher work roll. In addition, the oxide-rich near-surface layers formed on the samples were thicker and more discontinuous for the rougher work roll. The oxide distribution in the transverse direction could be correlated to the size of the rolling ridges, which were larger for the samples rolled with the rougher work roll. A critical work roll surface roughness was proposed to influence the initiation of shingles on the aluminum alloy surfaces. The extent of the near-surface damage and the surface features formed on the rolled aluminum alloys were shown to be dependent on, but not limited to, the work roll surface topography.

Nanoscopic Terraces, Mesas, and Ridges in Freely Standing Thin Films Sculpted by Supramolecular Oscillatory Surface Forces.

Freely standing thin liquid films containing supramolecular structures including micelles, nanoparticles, polyelectrolyte-surfactant complexes, and smectic liquid crystals undergo drainage via stratification. The layer-by-layer removal of these supramolecular structures manifests as stepwise thinning over time and a coexistence of domains and nanostructures of discretely different thickness. The layering of supramolecular structures in confined thin films contributes additional non-DLVO, supramolecular oscillatory surface forces to disjoining pressure, thus influencing both drainage kinetics and stability of thin films. Understanding and characterizing the spontaneous creation and evolution of nanoscopic topography of stratifying, freely standing thin liquid films have been long-standing challenges due to the absence of experimental techniques with the requisite spatial (thickness <10 nm) and temporal resolution (<1 ms). Using Interferometry Digital Imaging Optical Microscopy (IDIOM) protocols developed herein, we visualize and characterize size, shape, and evolution kinetics of nanoscopic mesas, terraces, and ridges. The exquisite thickness maps created using IDIOM protocols provide much needed and unprecedented insights into the role of supramolecular oscillatory surface forces in driving growth of such nanostructures as well as in controlling properties and stability of freely standing thin films and, more generally, of colloidal dispersions like foams.

Depth (Z-axis) control of cell morphologies on micropatterned surfaces

In this study, cell responses on micropatterned films that were changing in groove–ridge widths and pattern depth were investigated to compare the degree of size effects from X–Y and Z planes. Poly(caprolactone) films with five different groove–ridge sizes and three pattern depths were prepared by hot embossing technique. In general, the morphologies of osteoblast cell were not changed noticeably by the size changes in groove–ridges with the same depth size. However, cell morphologies were changed significantly when pattern depths were increased from 1.35 to 4.95 µm. Also, the cell morphology change between different groove–ridges was significant when the pattern depth was small (1.35 µm), and these effects were diminished or masked when the pattern depth was increased to 4.95 µm. Linear regression analysis further clarifies that unit size changes in depth may affect cell length and orientation rates 2.4 and 4 times, respectively, in comparison to rates obtained from X–Y planes.

Metastatic bladder cancer cells distinctively sense and respond to physical cues of collagen fibril-mimetic nanotopography.

Tumor metastasis is characterized by enhanced invasiveness and migration of tumor cells through the extracellular matrix (ECM), resulting in extravasation into the blood and lymph and colonization at secondary sites. The ECM provides a physical scaffold consisting of components such as collagen fibrils, which have distinct dimensions at the nanoscale. In addition to the interaction of peptide moieties with tumor cell integrin clusters, the ECM provides a physical guide for tumor cell migration. Using nanolithography we set out to mimic the physical dimensions of collagen fibrils using lined nanotopographical silicon surfaces and to explore whether metastatic tumor cells are uniquely able to respond to these physical dimensions. Etched silicon surfaces containing nanoscale lined patterns with varying trench and ridge sizes (65-500 nm) were evaluated for their ability to distinguish between a non-metastatic (253 J) and a highly metastatic (253 J-BV) derivative bladder cancer cell line. Enhanced alignment was distinctively observed for the metastatic cell lines on feature sizes that mimic the dimensions of collagen fibrils (65-100 nm lines, 1:1-1:1.5 pitch). Further, these sub-100 nm lines acted as guides for migration of metastatic cancer cells. Interestingly, even at this subcellular scale, metastatic cell migration was abrogated when cells were forced to move perpendicular to these lines. Compared to flat surfaces, 65 nm lines enhanced the formation of actin stress fibers and filopodia of metastatic cells. This was accompanied by increased formation of focal contacts, visualized by immunofluorescent staining of phospho-focal adhesion kinase along the protruding lamellipodia. Simple lined nanotopography appears to be an informative platform for studying the physical cues of the ECM in a pseudo-3D format and likely mimics physical aspects of collagen fibrils. Metastatic cancer cells appear distinctively well adapted to sense these features using filopodia protrusions to enhance their alignment and migration.

RESEARCH ON THE OPTIMUM SHAPE AND SIZE OF POTATO RIDGES – PARTIAL RESULTS FROM TRIAL YEAR 2013

The partial results from the research carried out in 2013 at the Potato Research and Development Station TA¢rgu Secuiesc on the size and shape of the ridges and the influence of planting density in the case of two varieties and two types of ridges (ridges in one row and two rows) are presented. The pedoclimatic conditions characteristic of this trial year were favorable for potato cultivation. In the study of the optimal shape of potato ridges three different shapes have been studied: triangular shape, trapezoidal shape and double-trapezoidal shape. In the study of the optimal size of potato ridges three different ridge sizes were made: with cross-sectional areas of  800 cm 2 , 1200 cm 2 and 1600 cm 2 . The biological material used in these two experiments was the Bella Rosa variety, which is part of the class A biological category. The research on the influence of planting density was conducted on two potato varieties planted in ridges in a single row and in two rows: one that forms many but small tubers, the class A Gared variety and the second one that forms fewer but larger tubers, the class A Bella Rosa variety. Experiments with three different planting densities for each type of variety and each type of ridge (ridges in one row and two rows) were carried out: 40.000 plants/ha, 60.000 plants/ha and 80.000 plants/ha. For all variants four rows were planted and the process was repeated four times. The common technology of ridge ploughing was used and mechanically performed phytosanitary treatments were executed with the usual products. To achieve the objectives the following elements were taken into consideration: - yield and production (kg/ha) - average weight of a tuber (g) - average number of tubers per nest - average number and weight of tubers under and over 40 mm per nest An analysis of variance was carried out for completely randomized plots and the data processing was accomplished by using average values, the “t-test” at 5%, 1%, 0,1% significant difference levels and the Duncan Multiple Range Test.

Primary cilia function regulates the length of the embryonic trunk axis and urogenital field in mice

The issues of whether and how some organs coordinate their size and shape with the blueprint of the embryo axis, while others appear to regulate their morphogenesis autonomously, remain poorly understood. Mutations in Ift144, encoding a component of the trafficking machinery of primary cilia assembly, result in a range of embryo patterning defects, affecting the limbs, skeleton and neural system. Here, we show that embryos of the mouse mutant Ift144twt develop gonads that are larger than wild-type. Investigation of the early patterning of the urogenital ridge revealed that the anterior–posterior domain of the gonad/mesonephros was extended at 10.5dpc, with no change in the length of the metanephros. In XY embryos, this extension resulted in an increase in testis cord number. Moreover, we observed a concomitant extension of the trunk axis in both sexes, with no change in the length of the tail domain or somite number. Our findings support a model in which: (1) primary cilia regulate embryonic trunk elongation; (2) the length of the trunk axis determines the size of the urogenital ridges; and (3) the gonad domain is partitioned into a number of testis cords that depends on the available space, rather than being divided a predetermined number of times to generate a specific number of cords.

Mode imaging and loss evaluation of semiconductor waveguides.

An imaging and loss evaluation method for semiconductor waveguides coupled with non-doped quantum wells is presented. Using the internal emission of the wells as a probe light source, the numbers and widths of the modes of waveguides with various ridge sizes were evaluated by CCD imaging, and the obtained values were consistent with effective index method calculation. Waveguide internal losses were obtained from analyses of the Fabry-Pérot fringes of waveguide emission spectra. We quantified the quality of 29 single-mode waveguide samples as an internal loss and variation of 10.2 ± 0.6 cm(-1).

Numerical study of silicon crystal ridge growth

The size of the ridge-like protrusions appearing on the external surface of dislocation-free 〈100〉 silicon crystals grown from a melt was studied theoretically. According to existing models the growth of the ridges is caused by the presence of {111} crystal planes at the crystal–melt interface. They affect the height of triple phase line, free surface orientation and the crystal growth angle. A numerical 2-dimensional model was proposed for the calculation of the size of the crystal ridges. The model included the effect of the undercooling of the crystal–melt interface on the crystal growth angle. The numerical model estimated the effect of the ridge size on the free surface at the triple phase line. The size of the crystal ridges was calculated for the 〈100〉 silicon crystals grown by the Czochralski process. It was shown that the crystal ridge growth is sensitive to the physical conditions at the triple phase line.

Taxonomic revision of the genusNeoheligmonellaDurette-Desset, 1971 (Nematoda, Heligmonellidae) parasitic in Muridae mainly from the Ethiopian Region

The genus Neoheligmonella Durette-Desset, 1971 (Nippostrongylinae) is revised and split into three genera, one of them with two subgenera. The new genera can be discriminated mainly by characters of the synlophe which had been not considered previously at the supraspecific level. These characters include the presence of a careen, the size of the right ridge relative to the left ridge, and the presence of gradients in the ridge size. The genus Neoheligmonella sensu stricto is proposed to include species with a careen, and it is divided into two subgenera: Neoheligmonella (Neoheligmonella) characterized by a right ridge measuring more than 45% of the ventral ridge of the careen, and Neoheligmonella (Duplantierus) n. subgen. with a right ridge measuring less than 45% of the ventral ridge of the careen. Dioufnema n. gen. includes one species with neither a careen nor hypertrophied ridges and having a bursa of type 1-3-1. Taranchonema n. gen. includes species without a careen, with the left ridge and the right ridge hypertrophied, and without a dorsal gradient in ridge size. A dichotomous key to the new genera and subgenera is provided. Five species of unknown synlophe, originally placed in the former genus Neoheligmonella and validated by other characters, are considered as Nippostrongylinae incertae sedis.

Research on the Optimum Shape and Size of Potato Ridges

The partial results from the research carried out in 2012 at the Potato Research and Development Station Tg. Secuiesc on the size and shape of the ridges and the influence of planting density in the case of two varieties and two types of ridges (ridges in one row and two rows) are presented. The results were heavily influenced by the unfavorable weather conditions in 2012 when there was a smaller amount of precipitation compared to the multiannual average rainfall during the growing season: -115.4 mm. The insufficient moisture resulted in the inhibition of potato tuberization, reabsorption of stolons and young tubers and in this period some of the water content in tubers passed into the leaves. In the study of the optimal shape of potato ridges three different shapes have been studied: triangular shape, trapezoidal shape and double-trapezoidal shape. In the study of the optimal size of potato ridges three different ridge sizes were made: with cross-sectional areas of 800 cm2 , 1200 cm2 and 1600 cm2. The biological material used in these two experiments was the Bella Rosa variety, which is part of the class A biological category. The research on the influence of planting density was conducted on two potato varieties planted in ridges in a single row and in two rows: one that forms many but small tubers, the class A Gared variety and the second one that forms fewer but larger tubers, the class A Bella Rosa variety. Experiments with three different planting densities for each type of variety and each type of ridge (ridges in one row and two rows) were carried out: 40.000 plants/ha, 60.000 plants/ha and 80,000 plants/ha. For all variants four rows were planted and the process was repeated four times. The common technology of ridge ploughing was used and mechanically performed phytosanitary treatments were executed with the usual products. To achieve the objectives the following elements were taken into consideration: yield and production (kg/ha), average weight of a tuber (g), average number of tubers in the nest. An analysis of variance was carried out for completely randomized plots and the data processing was accomplished by using average values, the “t-test” at 5%, 1%, 0.1% significant difference levels and the Duncan Multiple Range Test.

Morphological stability of oxygen- and nitrogen-covered Ru$(11\bar 21)$(112¯1)

Morphological stability of the atomically rough Ru(1121) surface upon annealing in NO2, O2, and NH3 at elevated temperatures has been studied using scanning tunneling microscopy (STM), low energy electron diffraction (LEED), and Auger electron spectroscopy. The surface becomes fully faceted and covered by oxygen after annealing at T ≥ 600 K in NO2 (10(-8) Torr) or O2 (10(-6) Torr). The LEED and STM studies reveal that the faceted surface consists of nanoscale ridges, exposing four facets (1011), (0111), (1010), and (0110) on the ridges, and the ridge size grows as the annealing temperature increases. Details of the facet structures and reconstructions have been observed. However, no evidence is found for faceting of Ru(1121) to occur upon annealing in NH3. Our findings should be important for development of Ru-based catalysts under oxygen-rich conditions.

Comment on “Trace fossil evidence for Ediacaran bilaterian animals with complex behaviors” by Chen et al. [Precambrian Res. 224 (2013) 690–701

Trace fossils from the Shibantan Member of the Denying Formation (551–541Ma) of South China, interpreted by Chen and colleagues as evidence of undermat feeding, epibenthic locomotion and temporary dwelling of a small worm-like animal (Metazoa, Bilateria), show four features incompatible with that interpretation: (1) bulbous ends, (2) interruptions, (3) variable width, (4) narrow ends and (5) beaded levees. These features are better explained as due to formation of a sorocarp base, looping upward, shape changing, cell aggregation and slime nodules, respectively, of the slug (grex or pseudoplasmodium) phase of a cellular slime mold comparable with living Dictyostelium discoideum (Amoebozoa, Mycetozoa). Another three features are found in worm as well as slime mold trails: (6) transverse markings, (7) central ridge and (8) small size. Similar observations can be made, and mycetozoan affinities considered for comparable trace fossils from the 550Ma Ediacaran Member of South Australia, 558Ma Ust Pinega Formation of Russia, 585–600Ma Tacuari Formation of Uruguay, 1100Ma Chorhat Sandstone of India and 2000–1800Ma Stirling Range Sandstone of Western Australia. Slime molds are terrestrial eucaryotic protists, and may have a fossil record extending back as far as the likely 1900Ma age of aquatic metazoans.

Engineered Contractile Skeletal Muscle Tissue on a Microgrooved Methacrylated Gelatin Substrate

To engineer tissue-like structures, cells must organize themselves into three-dimensional (3D) networks that mimic the native tissue microarchitecture. Microfabricated hydrogel substrates provide a potentially useful platform for directing cells into biomimetic tissue architecture in vitro. Here, we present microgrooved methacrylated gelatin hydrogels as a suitable platform to build muscle-like fibrous structures in a facile and highly reproducible fashion. Microgrooved hydrogel substrates with two different ridge sizes (50 and 100 μm) were fabricated to assess the effect of the distance between engineered myofibers on the orientation of the bridging C2C12 myoblasts and the formation of the resulting multinucleated myotubes. It was shown that although the ridge size did not significantly affect the C2C12 myoblast alignment, the wider-ridged micropatterned hydrogels generated more myotubes that were not aligned to the groove direction as compared to those on the smaller-ridge micropatterns. We also demonstrated that electrical stimulation improved the myoblast alignment and increased the diameter of the resulting myotubes. By using the microstructured methacrylated gelatin substrates, we built free-standing 3D muscle sheets, which contracted when electrically stimulated. Given their robust contractility and biomimetic microarchitecture, engineered tissues may find use in tissue engineering, biological studies, high-throughput drug screening, and biorobotics.

Effects of laser peening with different coverage areas on fatigue crack growth properties of 6061-T6 aluminum alloy

The effects of coverage area on fatigue crack growth (FCG) properties of 6061-T6 aluminum alloy subject to multiple laser peening (LP) impacts were investigated. Residual stress, micro-structure and fatigue striation pattern on fracture cross-sections were analyzed. Compressive residual stresses and dense dislocation arrangements can be found in the superficial layer after LP. LP coverage area has a direct influence on FCG properties as verified by different size of shell ridges and fatigue striation spacing on fracture cross-sections. Meanwhile, FCG rate decreases with the increase of compressive residual stresses distribution perpendicular to the crack growth direction in the initial FCG stage.

Development of micropatterned surfaces of poly(butylene succinate) by micromolding for guided tissue engineering

Native tissues present complex architectures at the micro- and nanoscale that dictate their biological function. Several microfabrication techniques have been employed for engineering polymeric surfaces that could replicate in vitro these micro- and nanofeatures. In this study, biomimetic surfaces of poly(butylene succinate) (PBS) were engineered by a micromolding technique. After the optimization of the system parameters, 20 surfaces with different combinations of groove and ridge sizes were developed and characterized by scanning electron microscopy (SEM). The influence of the engineered microfeatures over the viability and attachment of human adipose derived adult stem cells (hASCs) was evaluated. hASCs cultured onto the engineered surfaces were demonstrated to remain viable for all tested patterns. SEM and immunostaining showed adequate attachment and spreading of the stem cells for all the patterned groove/ridge combinations. This study indicated that it is possible to engineer micropatterned surfaces of PBS and that the developed structures could have great potential for tissue engineering where cell alignment is an essential requisite.