Journal articles: 'Composition gradient'

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Vazan, Allona, Ravit Helled, and Tristan Guillot. "Jupiter’s evolution with primordial composition gradients." Astronomy & Astrophysics 610 (February 2018): L14. http://dx.doi.org/10.1051/0004-6361/201732522.

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Recent formation and structure models of Jupiter suggest that the planet can have composition gradients and not be fully convective (adiabatic). This possibility directly affects our understanding of Jupiter’s bulk composition and origin. In this Letter we present Jupiter’s evolution with a primordial structure consisting of a relatively steep heavy-element gradient of 40 M⊕. We show that for a primordial structure with composition gradients, most of the mixing occurs in the outer part of the gradient during the early evolution (several 107 yr), leading to an adiabatic outer envelope (60% of Jupiter’s mass). We find that the composition gradient in the deep interior persists, suggesting that ~40% of Jupiter’s mass can be non-adiabatic with a higher temperature than the one derived from Jupiter’s atmospheric properties. The region that can potentially develop layered convection in Jupiter today is estimated to be limited to ~10% of the mass.

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Wei Zhang and Wai-Kuen Cham. "Gradient-Directed Multiexposure Composition." IEEE Transactions on Image Processing 21, no. 4 (April 2012): 2318–23. http://dx.doi.org/10.1109/tip.2011.2170079.

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Campos-Cerqueira, Marconi, and T. Mitchell Aide. "Changes in the acoustic structure and composition along a tropical elevational gradient." Journal of Ecoacoustics 1, no. 1 (December 6, 2017): 1. http://dx.doi.org/10.22261/jea.pnco7i.

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Elevational gradients influence the distribution and composition of animal species and can provide useful information for the development of conservation strategies in the context of climate change. Despite an increase in studies of species diversity along elevational gradients, there is still a lack of information about community responses to environmental gradients, in part because of the logistical limitations of sampling multiple taxa simultaneously. One solution is to use passive acoustic monitoring (PAM) to acquire and analyze information from different animal taxa simultaneously along an entire elevational gradient. To improve our understanding of how environmental gradients influence patterns of animal communities and to test the relationship between soundscapes and animal composition we investigated how variation in bird and anuran composition affect the acoustic structure and composition of the soundscapes along an elevation gradient. We used PAM deploying portable acoustic recorders along three elevational transects in the Luquillo Mountains (LM), Puerto Rico. We found that elevation plays a major role in structuring the acoustic community and that the soundscape composition reflected the same patterns of anuran and bird distribution and composition along the elevational gradient. This study shows how different animal taxa respond to environmental gradients and provide strong evidence for the use of soundscapes as a tool to describe and compare species distribution and composition across large spatial scales.

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Bresnahan, Brady L., and David L. Poerschke. "High-Throughput Multi-Principal Element Alloy Exploration Using a Novel Composition Gradient Sintering Technique." Metals 14, no. 5 (May 9, 2024): 558. http://dx.doi.org/10.3390/met14050558.

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This work demonstrates the capabilities and advantages of a novel sintering technique to fabricate bulk composition gradient materials. Pressure distribution calculations were used to compare several tooling geometries for use with current-activated, pressure-assisted densification or spark plasma sintering to densify a gradient along the long dimension of the specimen. The selected rectangular tooling design retains a low aspect ratio to ensure a uniform pressure distribution during consolidation by using a side loading configuration to form the gradient along the longest dimension. Composition gradients of NixCu1−x, MoxNb1−x, and MoNbTaWHfx (x from 0 to 1) were fabricated with the tooling. The microstructure, composition, and crystal structure were characterized along the gradient in the as-sintered condition and after annealing to partially homogenize the layers. The successful fabrication of a composition gradient in a difficult-to-process material like the refractory multi-principal element alloy system MoNbTaWHfx shows the utility of this approach for high-throughput screening of large material composition spaces.

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Garnett, D. R., and G. A. Shields. "The composition gradient across M81." Astrophysical Journal 317 (June 1987): 82. http://dx.doi.org/10.1086/165257.

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Li, Qiang, and Ming Qing Wu. "Based on the Gradient Source Representation of Functionally Gradient Materials." Applied Mechanics and Materials 496-500 (January 2014): 80–83. http://dx.doi.org/10.4028/www.scientific.net/amm.496-500.80.

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In the process of functionally gradient material entity modeling, in order to meet the design requirements, one needs to constantly change coefficient of material composition equation. In order to facilitate visual design of functionally graded material entities within the distribution, the method based on gradient material source be adopted to directly change the coefficient of material composition functions, and according to the coefficient of material composition equation function image to choose material composition functions. Homogenous approaching gradient is used, the feasibility of change of gradient direction transformatio is proved.

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Pero, Edgardo J. I., Paola A. Rueda Martín, and María C. Reynaga. "Species and genus richness and assemblage composition of stream caddisflies (Insecta: Trichoptera) vary with latitude in mountain rainforest of Argentina." Marine and Freshwater Research 70, no. 5 (2019): 687. http://dx.doi.org/10.1071/mf18209.

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Evidence found in results of studies of latitudinal gradients of benthic macroinvertebrate diversity is variable. This study analysed how species and genus richness and the composition of caddisfly assemblages (Insecta: Trichoptera) vary in Argentinean mountain forest through a latitudinal gradient from 22 to 28°S. Qualitative and quantitative data from 20 stream sites were compared. Assemblage richness and composition were analysed by comparing linear regressions, rank–abundance (RA) curves and non-metric multidimensional scaling (nMDS). Taxonomic richness increased from high to low latitude. RA curves showed changes in assemblage composition and structure across the latitudinal gradient. The nMDS revealed that the composition of the assemblages also changed along the latitudinal gradient. The patterns are similar to those observed in plants and vertebrates from the study region. The results are of particular note because a latitudinal gradient of aquatic insect diversity has rarely been observed in a narrow range.

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Prata, Eduardo Magalhães Borges, Aloysio De Pádua Teixeira, Carlos Alfredo Joly, and Marco Antonio Assis. "The role of climate on floristic composition in a latitudinal gradient in the Brazilian Atlantic Forest." Plant Ecology and Evolution 151, no. 3 (November 28, 2018): 303–13. http://dx.doi.org/10.5091/plecevo.2018.1407.

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Background and aims – Latitudinal gradients have an important influence on species distribution reflecting the effects of environmental factors such as temperature, rainfall, soil, and geographical distance. In the southeastern Brazilian Atlantic Forest, the role of climatic variables in the floristic composition is better known for altitudinal gradients of the Serra do Mar Mountains rather than for the latitudinal gradient. Here, we investigated the effects of mean annual temperature and rainfall on tree species distribution and composition in a latitudinal gradient in the Atlantic forest.Methods – We calculated each species frequency of occurrence and the latitudinal range. We used multivariate analyses (direct ordination, Hierarchical Clustering followed by Indicator Species analysis and NMDS) to investigate variation in floristic composition, and regression analyses to evaluate mean annual temperatures and rainfall effects on tree species composition along the latitudinal gradient (21°S to 28°S).Key results – A total of 789 species were registered, of which a majority (646 species) were present in less than 20% of the sampled areas, and only four species (0.5%) were present in more than 80% of the sampled areas. Only ten species (1.3%) reached the maximum latitudinal range (~6°). We found a strong correlation between variation in floristic composition and the spatial position in the latitudinal gradient. The cluster analyses detected two main floristic groups, one composed by the forests from Rio de Janeiro (21°S to 23°S) and the second by the forests from São Paulo, Paraná and Santa Catarina States (23°S to 28°S). The multiple regression analysis revealed a strong effect of the climatic variables on the variation of the floristic composition along the latitudinal gradient (r2 = 0.81, P < 0.001), where 62.82% of the variation were explained by mean annual temperature, 8.27% by annual rainfall and 10.45% by both variables together.Conclusions – The restricted distribution of most species may be explained by variations in mean annual temperature and annual rainfall along the latitudinal gradient. For instance, the decreasing mean annual temperature along the coast and the occurrence of frosts at higher latitudes may limit the southward distribution of some species while the lower annual rainfall (with marked seasonality) in the north of the gradient may limit the northward distribution of other species. Although mean annual temperature explained most of the variation in species composition along the latitudinal gradient, the abrupt variation in annual rainfall may explain the high floristic dissimilarity detected in the north of the gradient.

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Xu, C., S. E. Barnes, T. Wu, D. A. Fischer, D. M. DeLongchamp, J. D. Batteas, and K. L. Beers. "Solution and Surface Composition Gradients via Microfluidic Confinement: Fabrication of a Statistical-Copolymer-Brush Composition Gradient." Advanced Materials 18, no. 11 (June 6, 2006): 1427–30. http://dx.doi.org/10.1002/adma.200502341.

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Manaila, R., A. Devenyi, D. Biro, L. David, P. B. Barna, and A. Kovacs. "Multilayer TiAlN coatings with composition gradient." Surface and Coatings Technology 151-152 (March 2002): 21–25. http://dx.doi.org/10.1016/s0257-8972(01)01633-4.

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Huang, Jianguo, Izumi Ichinose, Toyoki Kunitake, and Aiko Nakao. "Zirconia−Titania Nanofilm with Composition Gradient." Nano Letters 2, no. 6 (June 2002): 669–72. http://dx.doi.org/10.1021/nl0255653.

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Tao Chen, Jun-Yan Zhu, A. Shamir, and Shi-Min Hu. "Motion-Aware Gradient Domain Video Composition." IEEE Transactions on Image Processing 22, no. 7 (July 2013): 2532–44. http://dx.doi.org/10.1109/tip.2013.2251642.

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Bochegov, V. I., L. N. Nikiforov, and I. A. Peshkova. "Experimental Study of the Effect of Gradient Inhomogeneity of the Bi100-C -SbC Crystal in the Range of 11 < C < 19 at. % on the Peltier Effect at a Temperature of About 100 K." LETI Transactions on Electrical Engineering & Computer Science 16, no. 2 (2023): 5–12. http://dx.doi.org/10.32603/2071-8985-2023-16-2-5-12.

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Presents the results of a study of the influence of gradient inhomogeneity of composition and temperature directed along the cleavage plane of varizon crystals of the Bi100-C-SbC system on the Peltier effect in the composition range corresponding to the semiconductor region of the interval 11 < C <19 at. %. It follows from the data obtained that, for a gradient-inhomogeneous sample in a given antimony concentration range at optimal current, the Peltier cooling value is significantly greater with co-directional gradients of temperature and band gap width than in the case when these gradients are oppositely directed. This means that the polarity effect of the Peltier phenomenon is clearly manifested.

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Connor, Stephanie J., Alexa C. Alexander-Trusiak, and Donald J. Baird. "Vulnerability of diatom communities in the Peace–Athabasca Delta to environmental change." PeerJ 6 (August 9, 2018): e5447. http://dx.doi.org/10.7717/peerj.5447.

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Habitat degradation associated with resource development is a major ecological concern, particularly in Canada’s boreal zone where limited information on biodiversity is available. Habitat degradation can lead to reductions in biodiversity and ecosystem function, especially when drivers of variability and diversity patterns have not been identified for a region of interest. In this study, the distribution of diatom genera in the Peace–Athabasca Delta in northeastern Alberta was examined in relation to seasonal, geographic, and alkalinity gradients. Grab samples of six abiotic variables (total dissolved nitrogen, total dissolved phosphorus, dissolved iron, turbidity, pH, and specific conductance (SPC)) were taken from 12 remote wetlands over three sampling periods, and regressed against an ordination of diatom community composition to identify key environmental drivers of diatom community variation. Indirect gradient analysis identified two major gradients among sites. First, separation of sites among sampling periods showed successional seasonal changes in diatom community composition. Second, separation of sites from the Peace sub-delta and Birch sub-delta showed a gradient of geographic separation. Direct gradient analysis failed to explain the underlying drivers of these two gradients, but did show that alkalinity is a key driver of diatom community composition in the Embarras sub-delta, and that these sites could be particularly vulnerable to community changes associated with acidification.

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Wayner, P. C., C. Y. Tung, M. Tirumala, and J. H. Yang. "Experimental Study of Evaporation in the Contact Line Region of a Thin Film of Hexane." Journal of Heat Transfer 107, no. 1 (February 1, 1985): 182–89. http://dx.doi.org/10.1115/1.3247376.

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The transport processes in the contact line region (junction of evaporating thin liquid film, vapor, and substrate) of stationary steady-state evaporating thin films of hexane with various bulk compositions were studied experimentally. The substrate temperature distribution and liquid film thickness profile were measured, analyzed, and compared with previous results on other systems. The results demonstrate that small changes in the bulk composition significantly alter the characteristics of the transport processes in the contact line region. The curvature gradient at the liquid-vapor interface is a strong function of evaporation rate and composition. Concentration and temperature gradients give interfacial shear stresses and flow patterns that enhance contact line stability.

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Park, Sang Hyun, Sang Won Myong, Yeon Gil Jung, and Ung Yu Paik. "Microstructural Evaluation and Mechanical Properties of Al₂O₃/ZrO₂ Layered Structure with Graded Interlayers." Solid State Phenomena 124-126 (June 2007): 1353–56. http://dx.doi.org/10.4028/www.scientific.net/ssp.124-126.1353.

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Layered structure with composition gradient between inner layer of alumina (Al2O3) and outer layer of zirconia ( ZrO2-3mol% Y2O3 ;TZ-3Y) was fabricated using a gel casting process for the inner layer and a dip coating process for the outer layer in an aqueous system. The interlayer with composition gradient was prepared by mixing the Al2O3 and TZ-3Y slips as a volume ratio. Dried green bodies of the inner layer were pre-sintered at 1100°C for 5hr. After pre-wetting the pre-sintered bodies, the dip coating was preformed with mixed slips. Two kinds of composition gradients in the interlayer were prepared to observe the effect of composition gradient on mechanical properties, with same thickness. One is continuous composition gradient from Al2O3 to TZ-3Y with 9:1 to 1:9 volume ratios, and the other is layered structure with 8:2, 6:4, 4:6, and 2:8 volume ratios of Al2O3 and TZ-3Y. After the dip coating with each mixed slip, the coated bodies were sintered at 1100°C for 1hr to prevent delamination between each layer. The last dip coating was performed with the TZ-3Y slip, and then sintered at 1600°C for 3hr. Microstructure and element analysis of the sintered bodies were observed using SEM. For measurement of flexural strength, a standard four-point banding test was conducted. Also, hardness and modulus were measured using micro- and nano-indentation techniques. The step-like gradient in microstructure and composition is achieved through the gel casting and dip coating processes, including a gradual change in H and E from the inner to outer layers.

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Dolbeth, Marina, Heliana Teixeira, João Carlos Marques, and Miguel Ângelo Pardal. "Feeding guild composition of a macrobenthic subtidal community along a depth gradient." Scientia Marina 73, no. 2 (March 16, 2009): 225–37. http://dx.doi.org/10.3989/scimar.2009.73n2225.

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Bush, Andrew M., and Roderic I. Brame. "Multiple paleoecological controls on the composition of marine fossil assemblages from the Frasnian (Late Devonian) of Virginia, with a comparison of ordination methods." Paleobiology 36, no. 4 (2010): 573–91. http://dx.doi.org/10.1666/07022.1.

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Ecological ordination can reveal gradients in the species composition of fossil assemblages that can be correlated with paleoenvironmental gradients. Ordinations of simulated data sets suggest that nonmetric multidimensional scaling (NMDS) generally produces less distorted results than detrended correspondence analysis (DCA). We ordinated 113 brachiopod-dominated samples from the Frasnian (Late Devonian) Brallier, Scherr, and lower Foreknobs Formations of southwest Virginia, which represent a range of siliciclastic marine paleoenvironments. A clear environmental signal in the ordination results was obscured by (apparently) opportunistic species that occurred at high abundance in multiple environments; samples dominated by these species aggregated in ordination space regardless of paleoenvironmental provenance. After the opportunist-dominated samples were removed, NMDS revealed a gradient in species composition that was highly correlated with substrate (grain size); a second, orthogonal gradient likely reflects variation in disturbance intensity or frequency within grain-size regimes. Additional environmental or ecological factors, such as oxygenation, may also be related to the gradients. These two gradients, plus the environmental factors that controlled the occurrence of opportunistic species, explain much of the variation in assemblage composition in the fauna. In general, the composition of fossil assemblages is probably influenced by multiple paleoecological and paleoenvironmental factors, but many of these can be decomposed and analyzed.

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Holt, Emily A., Bruce McCune, and Peter Neitlich. "Macrolichen communities in relation to soils and vegetation in the Noatak National Preserve, Alaska." Botany 87, no. 3 (March 2009): 241–52. http://dx.doi.org/10.1139/b08-142.

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Macrolichen community structure and its relation to environment in the Noatak National Preserve, Alaska, is described using a two-way stratified random sample. We found 201 macrolichen taxa. Two primary gradients in lichen species composition were related to substrate pH and vegetation physiognomy, grading from forests to high alpine communities. Site characteristics associated with the first community gradient are soil moisture and exposure. Both ends of this gradient, including protected forests and densely shrubby sites at one end and exposed, high elevation alpine sites at the other end, are relatively dry and well-drained. The mid-region of this gradient consists of mesic, lowland tundra habitats. The second gradient, related to substrate pH, is driven by the presence of Sphagnum moss contrasting with calcareous soils and bedrock. Combining these two gradients of lichen community composition, we found six groups of plots using two-way cluster analysis. Further, division of macrolichen species occurring in five or more plots yielded seven species groups, based on a combination of environmental factors and species distribution characteristics. This snapshot of macrolichen communities in Arctic Alaska serves as an important baseline for future comparisons to environments altered by changing climate and land use.

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Zhu, Chun, Yong Mei Xiong, Xu Dong Ma, Xian Dong Ke, and Zhi Yao Su. "Indicator Species Analysis of Forest Communities along a Disturbance Gradient in Guangzhou, China." Applied Mechanics and Materials 195-196 (August 2012): 1275–82. http://dx.doi.org/10.4028/www.scientific.net/amm.195-196.1275.

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In order to reveal the effect of disturbance on species composition and detect indicator species for disturbance gradients, we conducted an investigation of urban forest communities along a disturbance gradient in Guangzhou, China. Species richness in the tree layer and understory had no significant difference among disturbance gradients, but Simpson index, Shannon-Weiner index and Evenness index varied significantly.species diversity index decreased with disturbance gradient. Multi-Response Permutation Procedures (MRPP) revealed high significance in species composition of both tree and understory layer among different disturbance gradients. Twelve species from the tree layer and 25 from the understory were detected to characterize the forest communities with a certain disturbance regime by Indicator Species Analysis (ISA). Indicator species help enhance our understanding of species-environment relationship, and the ecological response of indicator species to disturbance can be used for monitoring forest environmental change.

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Karasov-Olson, Aviv, and Douglas A. Kelt. "Small mammal assemblage composition and habitat associations across an elevational gradient in southern California." Journal of Mammalogy 101, no. 1 (December 13, 2019): 92–106. http://dx.doi.org/10.1093/jmammal/gyz178.

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Abstract Elevational gradients coincide with expansive climatic gradients and diverse plant and animal communities. We evaluated the small mammal assemblages in eight distinct vegetation types across an elevational gradient in southern California, the Deep Canyon Transect, to determine how assemblage composition changes across the gradient and to identify species with similar habitat associations. Livetrapping efforts (4,800 trap-nights) yielded 1,097 captures of 713 individuals, representing 14 heteromyid and cricetid species. Heteromyids dominated the six lower-elevation vegetation types (< 1,300 m a.s.l.), whereas cricetids dominated the upper end of the gradient. Richness and diversity exhibited bimodal responses to elevation, which do not conform to mid-domain effect null predictions. Canonical correspondence analysis revealed that 75% of the variation in small mammal abundances was explainable by habitat characteristics, and cluster analysis grouped small mammals into three ecologically distinct groups based on their habitat associations. One contained only Chaetodipus penicillatus, while the others were comprised of low- and high-elevation species, respectively. The low-elevation species exhibit unusual levels of sympatry (and syntopy) among closely related species of pocket mice (Chaetodipus). Further efforts should investigate the mechanisms of coexistence for Chaetodipus species with nearly identical associations and seasonal effects on richness and diversity. Repeated surveys of entire gradients such as the Deep Canyon Transect will help refine our understanding of temporal dynamics of community assemblage and diversity.

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Liu, Chong, and Nathaniel L. Rosi. "Ternary gradient metal–organic frameworks." Faraday Discussions 201 (2017): 163–74. http://dx.doi.org/10.1039/c7fd00045f.

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Gradient MOFs contain directional gradients of either structure or functionality. We have successfully prepared two ternary gradient MOFs based on bMOF-100 analogues, namely bMOF-100/102/106 and bMOF-110/100/102, via cascade ligand exchange reactions. The cubic unit cell parameter discrepancy within an individual ternary gradient MOF crystal is as large as ∼1 nm, demonstrating the impressive compatibility and flexibility of the component MOF materials. Because of the presence of a continuum of unit cells, the pore diameters within individual crystals also change in a gradient fashion from ∼2.5 nm to ∼3.0 nm for bMOF-100/102/106, and from ∼2.2 nm to ∼2.7 nm for bMOF-110/100/102, indicating significant porosity gradients. Like previously reported binary gradient MOFs, the composition of the ternary gradient MOFs can be easily controlled by adjusting the reaction conditions. Finally, X-ray diffraction and microspectrophotometry were used to analyse fractured gradient MOF crystals by comparing unit cell parameters and absorbance spectra at different locations, thus revealing the profile of heterogeneity (i.e. gradient distribution of properties) and further confirming the formation of ternary gradient MOFs.

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Vílchez, J. M., B. E. J. Pagel, Angeles I. Díaz, Elena Terlevich, and M. G. Edmunds. "The chemical composition gradient across M 33." Monthly Notices of the Royal Astronomical Society 235, no. 3 (December 1988): 633–53. http://dx.doi.org/10.1093/mnras/235.3.633.

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Smither, R., K. Abu Saleem, M. Beno, C. Kurtz, A. Khounsary, and N. Abrosimov. "Diffraction efficiency and diffraction bandwidth of thermal-gradient and composition-gradient crystals." Review of Scientific Instruments 76, no. 12 (December 2005): 123107. http://dx.doi.org/10.1063/1.2130928.

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Catling, PC, and RJ Burt. "Studies of the Ground-Dwelling Mammals of Eucalypt Forests in South-Eastern New South Wales: the Effect of Environmental Variables on Distribution and Abundance." Wildlife Research 22, no. 6 (1995): 669. http://dx.doi.org/10.1071/wr9950669.

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The distribution and abundance of ground-dwelling mammals was examined in 13 areas within 500 000 ha of eucalypt (Eucalyptus) forest in SE New South Wales. Data are presented on the distribution and abundance of species in relation to 3 environmental gradient types involving 9 variables: 2 direct gradients (temperature, rainfall); 6 indirect gradients (aspect, steepness of slope, position on slope, landform profile around the site, altitude, season) and a resource gradient (lithology). Many species of ground-dwelling mammal of the forests of SE New South Wales were present along all gradients examined, although wide variation in abundance occurred for some species. Eight species were correlated with direct gradients and all species were correlated with at least one indirect gradient. There was wide variation and species diversity with lithology, but the variation was not related to nutrient status. Although variations in abundance occurred along environmental gradients, the composition of the ground-dwelling mammal fauna in SE New South Wales forests changed little. A fourth gradient type, the substrate gradient (biomass of plants), had the greatest effect, because in the short-term disturbances such as logging and fire play an important role. Disturbance can have a profound influence on the substrate gradient, but no influence on environmental gradients. The results are discussed in relation to the arboreal mammals and avifauna in the region and Environmental and Fauna Impact studies and forest management.

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BROWN, GARETT M. "LITHOLOGICAL AND PALEOCOMMUNITY VARIATION ON A MISSISSIPPIAN (TOURNAISIAN) CARBONATE RAMP, MONTANA, USA." PALAIOS 36, no. 3 (March 30, 2021): 95–114. http://dx.doi.org/10.2110/palo.2020.050.

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ABSTRACT The ecological structure of ancient marine communities is impacted by the environmental gradients controlling assemblage compositions and the heterogeneous distribution of sediment types. Closely spaced, replicate sampling of fauna has been suggested to mitigate the effects of such heterogeneity and improve gradient analyses, but this technique has rarely been combined with similar sampling of lithologic data. This study analyses lithological and faunal data to determine the environmental gradients controlling the composition of Mississippian fossil assemblages of the lower Madison Group in Montana. Eighty-one lithological and faunal samples were collected from four stratigraphic columns in Montana, which represent the deep-subtidal, foreshoal, and ooid-shoal depositional environments within one third-order depositional sequence. Cluster analysis identifies three distinct lithological associations across all depositional environments—crinoid-dominated carbonates, peloidal-crinoidal carbonates, and micritic-crinoidal carbonates. Cluster analysis and nonmetric multidimensional scaling (NMS) identifies a highly diverse brachiopod biofacies and a solitary coral-dominated biofacies along an onshore-offshore gradient. Carbonate point count data and orientation of solitary corals indicate that substrate and wave energy are two potential variables that covary with the onshore-offshore gradient. Overlaying lithological information on the NMS indicates a secondary gradient reflecting oxygen that is expressed by increasing bioturbation and gradation from brown to dark gray carbonates to medium-light gray carbonates. Taken together, these findings demonstrates how combining closely spaced, replicate sampling of lithologic and faunal data enhances multivariate analyses by uncovering underlying environmental gradients that control the variation in fossil assemblages.

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Bogale Worku, Belachew, Melese Genete Muluneh, and Tesfaye Molla. "Influence of Elevation and Anthropogenic Disturbance on Woody Species Composition, Diversity, and Stand Structure in Harego Mountain Forest, Northeastern Ethiopia." International Journal of Forestry Research 2023 (November 17, 2023): 1–17. http://dx.doi.org/10.1155/2023/8842408.

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Environmental variables like elevation affect species composition, diversity, distribution, density, and horizontal and upward growth. Ecologists are constantly working to better understand how species diversity varies along elevational gradients, particularly in mountainous ecosystems. Therefore, the purpose of this research was to examine the species’ horizontal and vertical structural diversity along the Harego Mountain Forest’s elevational gradient. The area was categorized into lower, middle, and upper elevations. A total of 67 (20 m × 20 m) plots were created along gradients of elevation 2,079–2,516 meters above sea level (m a.s.l.). Information for floristic composition, diversity, stand structure, and environmental variables were measured and recorded for each plot over the three elevational gradients. Data on anthropogenic disturbances were visually evaluated for every plot in every gradient of elevation. For the diversity analysis, Hill’s diversity statistics were employed. To find significant variations between the three elevational gradients in terms of Hill’s diversity number, stand structure, and environmental variables, the one-way analysis of variance with SPSS version 26 at the 0.05 level of significance was carried out. The finding revealed that 50 woody plants that belonged to 35 families and 44 genera in the 67 sample plots with an elevation of 2,079 to 2,516 were identified. Shrubs were dominant in each elevational gradient. Species richness, abundance, and Hill’s diversity number were all significantly ( p < 0.05 ) greater in the upper elevational gradient of the forest. On the other hand, all stand structures were significantly ( p < 0.05 ) higher in the middle elevational gradient. The effect of anthropogenic disturbances and environmental variables were clearly observed in the lower and upper elevational gradients than in the middle elevation. As a result, there were fewer seedlings, saplings, trees, and shrubs in the gradients of lower and higher elevations. For the conservation of the forest, it is crucial to pay special attention to biotic elements at lower elevations and abiotic factors at higher elevations. Accordingly, involving the local community in forest management, reducing anthropogenic pressure in and around the Harego Mountain Forest through tree planting in farmlands and woodlots and implementing physical soil and water conservation structures are recommended.

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Klaus, Manuela, and Christoph Genzel. "Nondestructive separation of residual stress and composition gradients in thin films by angle- and energy-dispersive X-ray diffraction. I. Theoretical concepts." Journal of Applied Crystallography 50, no. 1 (February 1, 2017): 252–64. http://dx.doi.org/10.1107/s1600576716020598.

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Different X-ray measurement and data evaluation concepts are presented, which allow for residual stress analysis in thin films with pronounced gradients in chemical composition. These gradients lead to a variation in the strain-free lattice parameter a 0 with respect to the film thickness and superimpose the lattice strain induced by the film's inherent stresses. Non-consideration of a 0(z) gradients is shown to lead to considerable errors (`ghost stresses') in the residual stress depth profiles. With the simulated example of a TiC x N1−x film with a pronounced carbon gradient, the first part of this series introduces four approaches, which permit the separation of residual stress and composition depth distributions at different levels of approximation. They are based on lattice spacing depth profile measurements performed in either the sin2ψ mode or the scattering vector mode, or in combinations of these two scanning modes. Depending on the approach used for separating the residual stress and composition gradients, angle- or energy-dispersive diffraction has to be applied, employing monochromatic X-ray sources available in the laboratory or either white high-energy synchrotron radiation or the Bremsstrahlung of conventional X-ray tubes, respectively. The methods introduced here assume a biaxial residual stress state within the film. For a triaxial residual stress state with σ33 ≠ 0, a separation of stress and composition gradients is not straightforward, because an a 0(z) gradient cannot be distinguished from the hydrostatic part of the stress tensor.

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Johnson, Christopher L., and Alison C. Dunn. "Composition controls soft hydrogel surface layer dimensions and contact mechanics." Biointerphases 17, no. 6 (November 2022): 061002. http://dx.doi.org/10.1116/6.0002047.

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Hydrogels are soft hydrated polymer networks that are widely used in research and industry due to their favorable properties and similarity to biological tissues. However, it has long been difficult to create a hydrogel emulating the heterogeneous structure of special tissues, such as cartilage. One potential avenue to develop a structural variation in a hydrogel is the “mold effect,” which has only recently been discovered to be caused by absorbed oxygen within the mold surface interfering with the polymerization. This induces a dilute gradient-density surface layer with altered properties. However, the precise structure of the gradient-surface layer and its contact response have not yet been characterized. Such knowledge would prove useful for designs of composite hydrogels with altered surface characteristics. To fully characterize the hydrogel gradient-surface layer, we created five hydrogel compositions of varying monomer and cross-linker content to encompass variations in the layer. Then, we used particle exclusion microscopy during indentation and creep experiments to probe the contact response of the gradient layer of each composition. These experiments showed that the dilute structure of the gradient layer follows evolving contact behavior allowing poroelastic squeeze-out at miniscule pressures. Stiffer compositions had thinner gradient layers. This knowledge can potentially be used to create hydrogels with a stiff load-bearing bulk with altered surface characteristics tailored for specific tribological applications.

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Kashimura, Keiichiro, Jun Fukushima, Tomoaki Namioka, Takashi Fujii, Hirotsugu Takizawa, and Hideoki Fukushima. "Microwave Heating Behavior in SiC Fiber-MO2 Mixtures (M = Ce, Zr)—Selective Heating of Micrometer-Sized Fibers Facilitated by ZrO2 Powder." Processes 8, no. 1 (January 1, 2020): 47. http://dx.doi.org/10.3390/pr8010047.

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SiC fiber-MO2 (M = Ce, Zr) mixtures with various compositions were heated by applying an 80 W microwave electric field, to investigate their heating rate, maximum temperature, and dielectric constant. For the SiC fiber-CeO2 mixture, all three parameters continued to increase as the weight ratio of the SiC fiber increased; in contrast, for the SiC fiber-ZrO2 mixture, these parameters reached a maximum value at a certain composition. A thermal gradient of 500 °C was observed at a microlevel in the SiC fiber-ZrO2 mixture, and hot spots were located in regions with a certain composition. This result not only contributes to designing a novel good microwave absorber but also presents new aspects with regard to high-temperature microwave processing, including the mechanism behind the high-temperature gradients on the order of micrometers as well as engineering applications that utilize these high-temperature gradients.

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Maulet, M., Zh B. Sagdoldina, B. K. Rakhadilov, D. N. Kakimzhanov, and N. M. Magazov. "Influence of the content of aluminum on the structure of gradient detonation coatings based on NiCr-Al." Bulletin of the Karaganda University. "Physics" Series 107, no. 3 (September 30, 2022): 18–24. http://dx.doi.org/10.31489/2022ph3/18-24.

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This paper studies the effects of aluminium content in the composite powder on the structure of detonation gradient coatings based on NiCr-Al. Gradient coatings were obtained by detonation spraying with a gradual stepwise decrease in the barrel filling volume with an acetylene-oxygen gas mixture from 50% to 25%. The elemental and phase composition, microstructure and surface roughness of coatings based on NiCr-Al with different aluminium content of 15%, 20%, and 30% were investigated. By varying the aluminium content in the powder composition, coatings with a gradient structure were obtained. The study results showed that the phase composition of the gradient coating strongly depends on the mass fraction of Al. In the case of an aluminium content of 30% in the composition of the composite powder, the formation of aluminium oxide was detected. It is established that under the same detonation deposition modes, the formation of the gradient structure of coatings will strongly depend on the aluminium content in the NiCr-Al composition. The study results showed that the optimal composition of the powder is NiCr – 80% and Al – 20% to obtain NiCr-Al coatings with a gradient structure.

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Økland, R. H. "A phytoecological study of the mire Northern Kisselbergmosen, SE. Norway. I. Introduction, flora, vegetation and ecological conditions." Sommerfeltia 8, no. 1 (October 1, 1989): 1. http://dx.doi.org/10.2478/som-1989-0001.

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Abstract A part of the mire complex N. Kisselbergmosen, termed the special area, is subjected to a detailed investigation of hydrotopography, species distributions, and ecological conditions. Species occurrences and distributions are related to four main complex-gradients; (1) the mire expanse - mire margin gradient, (2) the nutrient gradient, (3) the gradient in depth to the water table, and (4) a peat productivity gradient. The former two are termed broad-scale, the latter fine-scale gradients. A hydrotopographical mapping was made, including establishment of a detailed map of mire features and subfeatures, and construction of a map showing the topography of the water table. Two or three synsegments and seven catchments make up the special area. Broad-scale distributions of species were mapped in a contiguous 4x4 m grid, resulting in a classification of species to nine D-groups. Six zones reflecting variation along gradients ( 1) and (2) were discerned. The concepts of mineral soil water limit and fen plant limit were discussed by reference to hydrotopography, species distributions, and chemical composition of peat along transects. Fine-scale patterns were studied by use of 800 randomly placed plots, analyzed with respect to vegetational composition and provided with measurements of depth to the water table. Fluctuations of depth to the water table in the period 1980-82 was related to climate. Particular emphasis was put on studying parameters of the cumulative distribution functions of depth to the water table; between-year variation, interdependence, and estimation from few observations. Species were classified to seven W-groups according to relationships with the water table, and five series were considered along this gradient. The vegetation was classified into 32 site-types by a reticulate division of the ecological space spanned by the four gradients. These site-types were described by use of 654 randomly and 765 subjectively selected plots. The site-types were compared to main types of other works, and successional relationships of site-types were inferred from observed transitions and ecological measurements. Mechanisms responsible for vegetational variation along the four gradients are thoroughly discussed.

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Jiménez-Pacheco, Hugo, Gregorio Urbano Palma Figueroa, Javier Alonso Villegas Aragon, María del Carmen Camiña Pacheco, Antonio Erick Linares Flores Castro, and Lilia Mary Miranda Ramos. "Diffusion characteristics of dyeing in Polyester fiber garments referred to their mixtures with cotton and composition." Veritas 20, no. 2 (October 24, 2019): 59. http://dx.doi.org/10.35286/veritas.v20i2.244.

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Currently, textile dyeing companies determine their market according to the raw materials processed, which are based on 100% cotton fibers, these fibers are directed to an exclusive market and therefore these companies establish criteria of high quality standards in each of its processes, dyeing being one of the most demanding due to its fastness parameters and color specifications, these characteristics establish the competitiveness of expanding a product portfolio with the incursion of 100% fiber-based clothing polyester and with cotton blends.Some studies suggest the implementation of the dyeing process of these fibers, allowing the organization to have new production alternatives, dyeing processes for polyester and cotton are carried out with heat treatment between 60 °C and 130 °C respectively, with the use of dispersed and chemical dyes; as in the dyeing of Polyester-Cotton that are made in bathrooms established in each stage. Color and solidity tests are performed according to quality parameters, with light and wash fastness controls. Within these dyeing conditions it is essential to determine the thermal gradients to be applied, whose variable must be controlled to optimize the dyeing of polyester fibers and mixtures.The present study evaluates the pre-treatments and the temperature gradient behavior stage in the dyeing process of polyester fibers, taking into account the dyeing curve, in which only the temperature gradient varies. Mathis-ALT-B equipment is used for the dyeing process, for thermal gradient conditions of 135 °C with gradients of 0.3-4.0 °C/min, rotation speed 40-70 RPM, and as colorants were used Novacron, Terail and Liandisperse for cotton and polyester fibers respectively. The results show that the use of dispersants and anti-breakage agents work to prevent failures and improve the corresponding colors, but a high gradient increases the migration of the dye and breaks in the fibers, but in low gradients (2 ° C/min ) The quality of diffusion and dyeing is better and, therefore, prevents reprocessing in the dyeing stage.

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Santiago, Louis S., Edward A. G. Schuur, and Katia Silvera. "Nutrient cycling and plant–soil feedbacks along a precipitation gradient in lowland Panama." Journal of Tropical Ecology 21, no. 4 (June 27, 2005): 461–70. http://dx.doi.org/10.1017/s0266467405002464.

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This study addresses patterns of nutrient dynamics on a precipitation gradient (1800–3500 mm y−1) in lowland tropical forest with heterogeneous soil parent material, high plant species diversity and large changes in species composition. Mean foliar concentrations of phosphorus, potassium, calcium and magnesium decreased with increasing precipitation, whereas foliar carbon:nitrogen increased with increasing precipitation. Mean foliar nitrogen:phosphorus varied from 16.4–23.8 suggesting that plant productivity at these sites is limited by phosphorus. Total soil nitrogen increased as a function of foliar litter lignin:nitrogen, whereas net nitrogen mineralization rates decreased with increasing lignin:N indicating that as litter quality decreases, more soil nitrogen is held in soil organic matter and the mineralization of that nitrogen is slower. Extractable phosphorus in soil was negatively correlated with foliar litter lignin:phosphorus, illustrating effects of litter quality on soil phosphorus availability. Overall, the results suggest that variation in plant community composition along this precipitation gradient is tightly coupled with soil nutrient cycling. Much of our understanding of effects of precipitation on nutrient cycling in tropical forest is based on precipitation gradients across montane forest in Hawaii, where species composition and soil parent material are constant. Our results suggest that variation in parent material or species composition may confound predictions developed in model island systems.Resumen: Este estudio trata sobre los patrones de dinámica de nutrientes en un gradiente de precipitación (1800–3500 mm y−1) en un bosque tropical de tierras bajas con material parental heterogéneo, alta diversidad de especies de plantas, y un gran cambio en la composición de especies. Las concentraciones promedio de fósforo, potasio, calcio y magnesio disminuyen con un aumento en la precipitación, mientras que la proporción carbono:nitrógeno aumenta con un aumento en la precipitación. La proporción promedio de nitrógeno foliar:fósforo varía de 16.4 a 23.8, lo cual sugiere que estos sitios tienen limitaciones de fósforo. El nitrógeno total del suelo aumenta como una función de la proporción de lignina foliar de la hojarasca:nitrógeno, mientras que la tasa de mineralización del nitrógeno neto disminuye con un aumento de la proporción de lignina:nitrógeno, lo cual indica que mientras la calidad de la hojarasca disminuye, más nitrógeno del suelo es retenido en la materia orgánica y la mineralización de ese nitrógeno es más lenta. El fósforo extraíble está correlacionado negativamente con la proporción de lignina foliar de la hojarasca:fósforo, lo cual ilustra el efecto de la calidad de hojarasca en la disponibilidad de fósforo del suelo. En resumen, estos resultados sugieren que la variación en la composición de plantas de una comunidad a lo largo de este gradiente de precipitación tiene un efecto considerable en la retroalimentación de los ciclos nutricionales del suelo. Gran parte de nuestros conocimientos sobre el efecto de los gradientes de lluvia en ciclos nutricionales del suelo han sido basados en estudios de gradientes de precipitación de bosques de montaña en Hawaii, en donde tanto la composición de especies y el material parental del suelo son constantes. Nuestros resultados sugieren que la variación del material parental del suelo y la composición de especies pueden confundir las predicciones desarrolladas en sistemas modelos de islas.

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Jenkins, Chelsea E., and Steven M. Holland. "Continental-scale biogeographic variation: provinces versus gradients in the Upper Ordovician of Laurentia." Paleobiology 42, no. 3 (May 6, 2016): 410–25. http://dx.doi.org/10.1017/pab.2015.56.

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AbstractAlthough provinces are widely used to delimit large-scale variations in biotic composition, it is unknown to what extent such variations simply reflect large-scale gradients, much as has been shown at smaller scales for communities. We examine here whether four previously described Middle and Late Ordovician provinces on Laurentia are best described as distinct provinces or as biotic gradients through a combination of the Paleobiology Database and new field data. Both data sets indicate considerable overlap in faunal composition, with spatial patterns in Jaccard similarity, quantified Jaccard similarity, and nonmetric multidimensional scaling ordination structure that correspond to variations in substrate type, specifically from carbonate-dominated strata in western Laurentia to mixed carbonate–siliciclastic strata in the midcontinent to siliciclastic-dominated rocks in easternmost Laurentia. Because sampling was limited to shallow-subtidal settings, this gradient cannot be attributed to variations in water depth. Likewise, geographic distance accounts for only a quarter of the variation in faunal composition. This cross-continent faunal gradient increases in strength into the early Late Ordovician, and appears to represent increased siliciclastic influx into eastern Laurentia during the Taconic orogeny. These results raise the question of whether biogeographic provinces may be in general better interpreted and analyzed as biotic gradients rather than as discrete entities.

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Liu, Tie, Qiang Wang, Zhong Ying Wang, Dong Gang Li, and Ji Cheng He. "Alignment of Primary Al₃Ni Phases in Hypereutectic Al-Ni Alloys with Various Compositions under High Magnetic Field Gradients." Materials Science Forum 649 (May 2010): 165–69. http://dx.doi.org/10.4028/www.scientific.net/msf.649.165.

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The microstructural changes of the primary Al3Ni phases in hypereutectic Al-Ni alloys solidified under various high magnetic field gradients were investigated. It was found that the application of a magnetic field gradient induced an aligned structure of the primary Al3Ni phases similar to those in a high uniform magnetic field. However, the high magnetic field gradient showed more obvious effect on the alignment of the primary Al3Ni phases than the uniform magnetic field, although this effect strongly depended on the alloy composition.

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Jeon, Yong Min, Si Hong Ryu, Min Jun Kim, and Seong Eui Lee. "Study on Ag-Ti Thin Film Structure with Compositional Gradient Fabricated by Sputtering Process." Korean Journal of Metals and Materials 61, no. 12 (December 5, 2023): 909–14. http://dx.doi.org/10.3365/kjmm.2023.61.12.909.

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In this study, a composition-gradient thin film was applied for the formation of intermediate layer of Ti seed layer for an stable electrode stack Ag metal layer. Various composition of Ag-Ti hetero metal layer were simultaneously deposited by using the sputtering process with Ti and Ag target, respectively. An intermediate layer was deposited at a gradient composition ratio such as 5:5 and 7:3. In addition, the optimal deposition conditions were evaluated by confirming the plasma codition such as density of plasma ion, plasma potential with the Langmuir Probe (Hiden ESPion). Flow rate, power, and composition ratio were optimized as variables for thin film structures of compositional gradient thin films. In addition, thin film samples were heat treated at 200 ℃, 300 ℃, and 400 ℃ to relieve the residual stress between the interface of laminated thin films. Under these conditions, a composition-gradient thin film was evaluated by XRD (X-Ray Diffraction, SmartLab Rigaku 9kW), SEM (Scanning Electron Microscope, Nova NanoSEM 450), and EDS (energy dispersive X-ray spectroscopy). As a result of the measurement, it was confirmed that interfacial diffusion occurred due to the composition gradient thin film. When the composition gradient intermediate layer was applied to thin film stack, the residual stress increased more than that of single thin film stack. However, after stress relief annealing, residual stress was dramatically decreased compared to single stack.

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Tesfay, Fikrey, Yitebitu Moges, and Zebene Asfaw. "Woody Species Composition, Structure, and Carbon Stock of Coffee-Based Agroforestry System along an Elevation Gradient in the Moist Mid-Highlands of Southern Ethiopia." International Journal of Forestry Research 2022 (June 28, 2022): 1–12. http://dx.doi.org/10.1155/2022/4729336.

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There is a limited effort in Ethiopia to study scientifically the ecological features of traditional coffee-based agroforestry systems. This study was initiated to determine the structure, composition, and carbon stock of woody species along an elevation gradient of a traditional coffee-based agroforestry system in Yirgacheffe district, southern Ethiopia. Woody plants’ inventory was conducted in thirty-eight sampling quadrats (20 ∗ 20 m) along five elevation contours and eight transects. Thirty-eight soil samples were taken from randomly selected subplots at 0–30 cm soil depths. In this study 32, woody plant species representing 23 families were recorded. Species richness ranged from 13–17 along the elevation gradient. Woody plant diversity indices appear to have a slight variation with increasing elevation gradient. Shade tree and coffee shrub density, DBH, and height showed significant variations along the elevation gradient. Total aboveground woody biomass carbon stock along elevation gradient ranged from 11.07 to 27.48 Mg·ha−1. Soil organic carbon stock was slightly different across elevation gradients with a mean range of 83.91 to 89.29 Mg·ha−1. These indicate that the agroforestry system has significant potential of storing and enhancing ecosystem carbon stocks across all the elevation gradients. The findings generally show that agroforestry systems in the study area are diverse, structurally complex with significant carbon storage in the soil and woody biomass.

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Barkan, Nezahat Pınar, Mathieu Chevalier, Jean-Nicolas Pradervand, and Antoine Guisan. "Alteration of Bumblebee Venom Composition toward Higher Elevation." Toxins 12, no. 1 (December 19, 2019): 4. http://dx.doi.org/10.3390/toxins12010004.

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Venomous animals use venom, a complex biofluid composed of unique mixtures of proteins and peptides, for either predation or defense. Bumblebees, which occur in various habitats due to their unique thermoregulatory properties, mainly use venom for defense. Herein, we conducted an exploratory analysis of the venom composition of a bumblebee species (Bombus pascuorum) along an elevation gradient in the western Swiss Alps using shot-gun proteomic approaches to assess whether their defense mechanism varies along the gradient. The gradient was characterized by high temperatures and low humidity at low elevations and low temperatures and high humidity at high elevations. Venom composition is changing along the elevation gradient, with proteomic variation in the abundances of pain-inducing and allergenic proteins. In particular, the abundance of phospholipase A2-like, the main component of bumblebee venom, gradually decreases toward higher elevation (lower temperature), suggesting venom alteration and thus a decrease in bumblebee defense towards harsher environments. Larger datasets may complement this study to validate the observed novel trends.

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Wang, Jingye, Bin Sheng, Ping Li, Yuxi Jin, and David Dagan Feng. "Illumination-Guided Video Composition via Gradient Consistency Optimization." IEEE Transactions on Image Processing 28, no. 10 (October 2019): 5077–90. http://dx.doi.org/10.1109/tip.2019.2916769.

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Leoni, Matteo, Paolo Scardi, Renato Pelosato, Isabella Natali Sora, Giovanni Dotelli, Paola Gallo Stampino, and Arianna Lo Presti. "Phase composition gradient in leached polluted cement monoliths." Cement and Concrete Research 37, no. 11 (November 2007): 1483–95. http://dx.doi.org/10.1016/j.cemconres.2007.08.013.

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Tokuyama, Hideaki, Masahiro Sasaki, and Shuji Sakohara. "Preparation of a novel composition-gradient thermosensitive gel." Colloids and Surfaces A: Physicochemical and Engineering Aspects 273, no. 1-3 (February 2006): 70–74. http://dx.doi.org/10.1016/j.colsurfa.2005.08.006.

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Yang, Shuoguang, Mengdi Wang, and Ethan X. Fang. "Multilevel Stochastic Gradient Methods for Nested Composition Optimization." SIAM Journal on Optimization 29, no. 1 (January 2019): 616–59. http://dx.doi.org/10.1137/18m1164846.

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Wu, Hui, ZhaoHui Su, Yuki Terayama, and Atsushi Takahara. "Polystyrene-based blend nanorods with gradient composition distribution." Science China Chemistry 55, no. 5 (February 16, 2012): 726–34. http://dx.doi.org/10.1007/s11426-012-4501-5.

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Liu, Wenxin, Shengqian Guo, Huiping Zhang, Yun Chen, Yizhen Shao, and Zhiliang Yuan. "Effect of Altitude Gradients on the Spatial Distribution Mechanism of Soil Bacteria in Temperate Deciduous Broad-Leaved Forests." Microorganisms 12, no. 6 (May 21, 2024): 1034. http://dx.doi.org/10.3390/microorganisms12061034.

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Soil bacteria are an important part of the forest ecosystem, and they play a crucial role in driving energy flow and material circulation. Currently, many uncertainties remain about how the composition and distribution patterns of bacterial communities change along altitude gradients, especially in forest ecosystems with strong altitude gradients in climate, vegetation, and soil properties. Based on dynamic site monitoring of the Baiyun Mountain Forest National Park (33°38′–33°42′ N, 111°47′–111°51′ E), this study used Illumina technology to sequence 120 soil samples at the site and explored the spatial distribution mechanisms and ecological processes of soil bacteria under different altitude gradients. Our results showed that the composition of soil bacterial communities varied significantly between different altitude gradients, affecting soil bacterial community building by influencing the balance between deterministic and stochastic processes; in addition, bacterial communities exhibited broader ecological niche widths and a greater degree of stochasticity under low-altitude conditions, implying that, at lower altitudes, community assembly is predominantly influenced by stochastic processes. Light was the dominant environmental factor that influenced variation in the entire bacterial community as well as other taxa across different altitude gradients. Moreover, changes in the altitude gradient could cause significant differences in the diversity and community composition of bacterial taxa. Our study revealed significant differences in bacterial community composition in the soil under different altitude gradients. The bacterial communities at low elevation gradients were mainly controlled by stochasticity processes, and bacterial community assembly was strongly influenced by deterministic processes at middle altitudes. Furthermore, light was an important environmental factor that affects differences. This study revealed that the change of altitude gradient had an important effect on the development of the soil bacterial community and provided a theoretical basis for the sustainable development and management of soil bacteria.

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Nahry and Noor Syiffa Fadillah. "The Empirical Study on the Impact of Road Gradient and Truck Composition on the Toll Road Traffic Performance." E3S Web of Conferences 65 (2018): 09003. http://dx.doi.org/10.1051/e3sconf/20186509003.

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The Jakarta Outer Ring Road (JORR) is a toll road system that circles the outskirts of Jakarta, where the purpose of this road is to reduce congestion on the street network of the city centre of Jakarta. However, the high composition of trucks in JORR resulted in congestion, and moreover it is suspected that the steep gradient of this road has contributed to this situation. This study aims to investigate the impact of road gradient on the trucks and the overall traffic performance from macroscopic view point. This study is the complement to a similar study that has been done in JORR previously, to confirm the result. The previous study was based on the Vissim simulation, while this paper will be entirely focused on an empirical study. Using the data obtained from 24-hour traffic recording on selected JORR sections that represent various gradients, traffic flow models are generated, and the effect of gradient could be assessed. The speed difference between trucks and non-trucks shows 56.2%~127% gap as the result of different gradient occurred. The overall free flow speed (uf) difference of different gradient is up to 27.3%. This result will benefit to the transport authority to justify the policy concerning the existence of trucks in the traffic flow, particularly in the condition at which trucks are regarded as a culprit of traffic congestion.

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Wu, Dong Jiang, Xiao Kang Liang, Qian Li, and Li Jia Jiang. "Fabrication of SS316L/Ni25 Functionally Gradient Materials Using Laser Engineered Net Shaping." Materials Science Forum 675-677 (February 2011): 803–6. http://dx.doi.org/10.4028/www.scientific.net/msf.675-677.803.

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Functionally gradient materials(FGMs) were successfully fabricated with compositions gradually changed from 100% stainless steel 316L to 100% Ni25 alloy using laser engineered net shaping(LENS) technology. The microstructure characterization, composition analysis and microhardness along the gradient direction are investigated. Meanwhile, the defects in the sample such as cracks and pores are analyzed. The results indicated that the microstructure evolves from columnar dendrite to cellular-crystal or equiaxed dendrite.

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Lyngå, Gösta. "The stellar disk component: distribution, motions, age and stellar composition." Symposium - International Astronomical Union 106 (1985): 133–42. http://dx.doi.org/10.1017/s007418090024223x.

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The distribution of the stellar disk component is studied with particular emphasis on the properties of open clusters. A scale height of 80 pc is found for clusters younger than 109 years while the scale height is 200 pc for older clusters. A radial metallicity gradient in the disk is confirmed but there seem to be significant abundance variations apart from this. There are radial gradients in age as well as in linear diameter. Kinematically, there are a number of regions in the Milky Way with systematic radial velocity residuals.

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HE, GANG, CHAO PENG, MINGZHONG HE, JIANHE HONG, HAIFENG LI, and YANSHENG GONG. "COMBINATORIAL PREPARATION AND FERROELECTRIC PROPERTIES OF COMPOSITIONALLY GRADIENT PZT THIN FILMS." Functional Materials Letters 06, no. 03 (May 28, 2013): 1350036. http://dx.doi.org/10.1142/s1793604713500367.

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Using a combinatorial synthesis process, compositionally gradient PZT thin films were conveniently prepared by a chemical solution decomposition (CSD) method. The thin films showed a perovskite structure with (111)-preferred orientation and a thickness of around 450 nm. The surface morphology and ferroelectric properties were significantly different, depending on the direction of compositional gradient. The detailed composition and gradient of the composition was seen to affect the property of compositionally gradient PZT thin films. The gradient thin film PZT654, with a Zr:Ti ratio of 6:4 at the bottom of the film nearest to the substrate, and with an total composition around the morphotropic phase boundary (MPB, x = 0.52) showed favorable ferroelectric properties. However, no typical offset of the hysteresis loops was observed in our work.

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Wróbel, Marek, and Andriy Burbelko. "A Diffusion Model of Binary Systems Controlled by Chemical Potential Gradient." Journal of Casting & Materials Engineering 6, no. 2 (April 27, 2022): 39–44. http://dx.doi.org/10.7494/jcme.2022.6.2.39.

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The paper presents a model of diffusion in a single phase with chemical potential gradient as the driving force of the process. Fick’s laws are strictly empirical and the assumption that the concentration gradients are the driving forces of diffusion is far from precise. Instead, the gradient of chemical potential μi of component i is the real driving force. The matter of governing equations of models that incorporate this approach will be raised and discussed in this article. One of more important features is the ability to acquire results where diffusion against the concentration gradient may occur. The presented model uses the Finite Difference Method (FDM) and employs the CALPHAD method to obtain chemical potentials. The calculations of chemical potential are carried out for instant conditions – temperature and composition – in the entire task domain by Thermo-Calc via a TQ-Interface. Then the heterogeneity of chemical potentials is translated into mass transfer for each individual element. Calculations of two modelling tasks for one-dimension diffusion field were carried out. First: isothermal conditions with linear initial composition distribution and second: constant temperature gradient with uniform chemical composition in the specimen. Results for two binary solid solutions: Fe-C and Fe-Si, in the FCC phase for the given tasks will be presented. Modelling allows us to estimate the time needed to reach a desired state in a particular equilibrium or quasi-equilibrium state. It also shows the path of the composition change during the process. This can be used to determine whether the system at some point is getting close to the formation of another phase due to significant deviation from its initial conditions.

Journal articles on the topic 'Composition gradient'

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