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The paper describes a theoretical study of adhesive friction at elastic–plastic contact of rough surfaces based on n-point asperity model. Well defined adhesion index and plasticity index are used to study the prospective situations arising out of variation in load, material properties, and surface roughness. Results are obtained for the behavior of friction force, applied load, and coefficient of friction for different combinations of adhesion index, plasticity index and mean separation of surfaces. The results obtained are in line with earlier models. It is observed that the tensile load required in maintaining a separation increases with increase in adhesion effect and extent of plastic deformation. Also coefficient of friction increases with adhesion effect.

The estimated undrained shear strength (su) is often not a unique value because it can be evaluated by various test types and/or procedures, such as different failure modes, shear strain rates, and boundary conditions. This study explores (1) the relationship between reference undrained shear strength and in situ shear wave velocity in terms of the effective overburden stress, and (2) the independent relationships to evaluate the undrained shear strength with special consideration of different directional and polarization modes (VH, HV, HH shear waves), which has not been reported. This evaluation is done via a worldwide database compiled from 43 well-documented geotechnical test sites associated with soft ground. Finally, new correlation models are proposed to estimate the undrained shear strength based on the in situ shear wave velocity as well as the plasticity index or the overconsolidation ratio. The application of the shear wave velocity-undrained shear strength relation is illustrated through two independent case studies. The proposed relationships are expected to contribute to reasonable estimates of undrained shear strength as well as offer practical guidance on even extrapolation beyond the data that is available to geotechnical engineers. [ABSTRACT FROM AUTHOR]

Clays are key elements not only in geological and environmental processes, but also in many human activities. To differentiate clays from other soils, AIPEA and CMS highlight plasticity as the clays' most distinctive characteristic. However, the lack of any reliable plasticity yardstick makes the particle-size-criteria to be more widespread. In a previous work, the authors found some innovative ratios between the plasticity index (PI) and the liquid limit (LL) which allowed the clays' boundary to be established according to a plasticity basis. As plasticity is directly associated with toughness, different published data containing valuable information have been processed in this study by plotting toughness values against PI/LL ratios. In this way, the soundness of the previous authors' finding has been checked. It is demonstrated that a fine-grained material can be defined as a clay when PI ≥ LL/2, while a material is moderately or slightly clayey if LL/3 < PI < LL/2, such that when PI ≤ LL/3 the influence of clay minerals is much reduced. Apart from an updated classification of soil for engineering purposes, a new textural soil classification is presented, alternative to the USDA one, which allows the real nature of a soil to be known accurately by means of plasticity tests and simple sieving instead of particle-size sedimentation methods. [ABSTRACT FROM AUTHOR]

Expansive soils swell when they come in contact with water and shrink upon drying. Use of admixtures to prevent volume changes is the most common and economical solution to deal with this problem. The purpose of this paper is to check the suitability of lime, silica fume (SF) and a mixture of SF and lime (SFLM) for improving engineering characteristics of expansive soils. SFLM was prepared using five percent SF and ten percent lime. Four replacement levels of lime, SF and SFLM were considered which include five percent, ten percent, fifteen percent and twenty percent. The aging effects on specimens were studied at 7 days, 14 days and 28 days. The unconfined compressive strength of soil increased by thirty two percent by adding fifteen percent SFLM whereas reduction in swell and swell pressure reached ninety eight percent and eighty seven percent, respectively. Physical properties (such as consistency limits and resistance to swell potential) improved by adding twelve percent to fifteen percent lime or four percent to seven percent SF. [ABSTRACT FROM AUTHOR]

Copyright of Academic Journal of Agriculture / Akademik Ziraat Dergisi is the property of University of Ordu, Faculty of Agriculture, Academic Journal of Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ceramica is the property of Associacao Brasileira de Ceramica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The number of revision joint replacements has been increasing substantially over the last few years. Understanding their failure mechanism is extremely important for improving the design and material selection of current implants. This study includes ten retrieved and four new mildly cross-linked ultra-high molecular weight polyethylene (UHMWPE) acetabular liners. Among them, most of the prostheses (n = 5) were reported to be revised and replaced due to aseptic loosening, followed by painful joint (n = 2), dislocation (n = 1), intra articular ossification (n = 1), combination of wear (liner) and osteolysis (stem) (n=1). Surface deviations (wear, material inflation and roughness), oxidative degradation and change of material properties were measured using micro-computed tomography (micro-CT) scan, 3D laser scanning microscopy, raman spectroscopy and nanoindentation, respectively. Prostheses having eccentric worn areas had much higher linear wear rates (228.01 ± 35.51 µm/year) compared to that of centrically worn prostheses (96.71 ± 10.83 µm/year). Oxidation index (OI) showed similar trends to the surface penetration depth. Among them, sample 10 exhibited the highest OI across the contact area and the rim of the cup liner. It also had the lowest hardness/elasticity ratio. Overall, wear and creep, oxidative degradation and reduced hardness/elasticity ratio all contributed to the premature failure of the UHMWPE acetabular cup liners. [ABSTRACT FROM AUTHOR]

Precipitation is a primary environmental factor in the semiarid grasslands of northern China. With increased concentrations of atmospheric greenhouse gases, precipitation regimes will change, and high-impact weather events may be more common. Currently, many ecophysiological indicators are known to reflect drought conditions, but these indicators vary greatly among species, and few studies focus on the applicability of these drought indicators under high CO conditions. In this study, five precipitation levels (− 30%, − 15%, control, + 15%, and + 30%) were used to simulate the effects of precipitation change on 18 ecophysiological characteristics in Stipa bungeana, including leaf area, plant height, leaf nitrogen (N), and chlorophyll content, among others. Two levels of CO concentration (ambient, 390 ppm; 550 ppm) were used to simulate the effects of elevated CO on these drought indicators. Using gray relational analysis and phenotypic plasticity analysis, we found that total leaf area or leaf number (morphology), leaf water potential or leaf water content (physiology), and aboveground biomass better reflected the water status of S. bungeana under ambient and elevated CO than the 13 other analyzed variables. The sensitivity of drought indicators changed under the elevated CO condition. By quantifying the relationship between precipitation and the five most sensitive indicators, we found that the thresholds of precipitation decreased under elevated CO concentration. These results will be useful for objective monitoring and assessment of the occurrence and development of drought events in S. bungeana grasslands. [ABSTRACT FROM AUTHOR]

Key message: We analyzed the shade tolerance of a tropical tree species based on the plasticity of 22 photosynthetic traits. Carpotroche brasiliensis leaves have characteristics of a shade-tolerant species, with low photosynthetic plasticity.Abstract: The objective of this study was to evaluate the photosynthetic plasticity of young Carpotroche brasiliensis plants in response to different light environments. This tropical tree species has some shade-tolerant traits, such as large and fleshy fruits, seeds with a high water content, and the ability for natural regeneration in the forest understory. In this way, we tested the hypothesis that, at the leaf scale, young C. brasiliensis plants have photosynthetic characteristics of shade-tolerant species, with low photosynthetic plasticity when grown under different light environments. For this, seedlings were subjected to four light treatments (60, 35, 25, and 15% full sunlight, corresponding to about 20.9, 11.9, 9.1, and 5.4 mol photons m−2 day−1, respectively) for 5 months. We evaluated the photosynthetic plasticity at the leaf scale through morphological and anatomical variables, as well as variables associated with the diffusive, photochemical, and biochemistry phases of photosynthesis. All key photosynthetic variables measured exhibited values of typical shaded leaves. The highest simplified relative distance plasticity index (RDPI) for light treatments was found for light compensation point (0.32), performance index (0.30), photochemical reflectance index (0.30), mesophyll conductance (0.27), dark respiration rate (0.27), and leaf area (0.19). The lowest RDPI for light treatments was found for the leaf anatomical variables (< 0.1). From the 22 photosynthesis-related variables analyzed, we conclude that, on a leaf scale, young C. brasiliensis plants exhibit characteristics of a typical shade-tolerant species. Based on our results, we can recommend the plantation of C. brasiliensis seedlings in forest enrichment programs or agroforestry systems, in which other tree species are present providing light environments below 35% full sunlight or about 10 mol photons m−2 day−1. [ABSTRACT FROM AUTHOR]

Using a ring shear apparatus, the variation in the residual strength characteristics of 21 groups of saturated clay soil samples were experimentally investigated, and the results are discussed in this paper. The clay soil samples had different plasticity indexes under 10 different consolidation conditions. The influences of shear rate, over-consolidation ratio, plasticity index, and multi-stage shear mode on the residual strength were investigated. New shear strength variation trend data and a corresponding equation for shear strength calculations as a function of plasticity index of soils under large deformation are presented. The experimental results indicate that 1) both the shear rate and over-consolidation ratio have a negligible influence on the residual strength; 2) the residual strength gradually decreases as the plasticity index increases; 3) the residual strength shows a significant nonlinearity with the normal stress when subjected to low- or high-levels of normal stress; 4) the internal friction angle of drained clay decreases as the plasticity index increases under large deformation. Finally, a formula is proposed to describe the relationship between the residual inner friction angle and plasticity index. [ABSTRACT FROM AUTHOR]

A model for pore water pressure accumulation and settlement of saturated clay layer induced by uniform and irregular cyclic shear strains was developed by concerning the direction of cyclic shear strain. To apply this model to any kinds of clay, the effects of Atterberg's limits of cohesive clay on the cyclic shear-induced pore water pressure and the settlement were observed by using the strain-controlled cyclic simple shear test apparatus which can control the cyclic shear direction. In conclusion, the effects of Atterberg's limits of clay on the cyclic shear-induced pore water pressure accumulation and settlement were clarified by using the cumulative shear strain. Based on the experimental results, estimation methods for the pore water pressure accumulation and post-cyclic settlement of clay with a wide range of Atterberg's limits were developed. Furthermore, to apply the proposed methods to the earthquake-induced ground motions, a transformation procedure of irregular cyclic shears to the equivalent uniform ones including the effect of cyclic shear direction was developed and the practical applicability was confirmed. [ABSTRACT FROM AUTHOR]

The change in the shear modulus of clays under repeat environmental loads is an important factor in the design of offshore and onshore foundations. A degradation model for the shear modulus of soft clays that considers the effects of the number of cycles, the cyclic stress ratio, the loading frequency and the plasticity index is proposed. A series of undrained cyclic triaxial tests on undisturbed Shanghai marine clays were conducted. Experimental results reveal that the shear modulus degradation index has a logarithmic relationship with the number of cycles, decreases linearly with the cyclic stress ratio, and increases linearly with the loading frequency when plotted in log-log coordinates. Further study using existing data from other research shows that the degradation index decreases with plasticity index, I P . Based on the test results, a new degradation model is proposed which considers these factors explicitly. The main feature of the new model is that only one set of parameters for each type of clay is required for the prediction of shear modulus degradation. The applicability of the present model is verified by five soft clays with different plasticity indices and loading conditions. [ABSTRACT FROM AUTHOR]

The quantity of water that might be attracted by soil particles (aggregates) depends on the physico-chemical properties of minerals comprising those particles (aggregates). The intensity of electro-magnetic fields surrounding fine particles controls the thickness of water films which are adsorbed by them. The new formula describing a nonlinear relationship between liquid limit and plasticity index values is presented in this paper. The correctness of the proposed formula was verified using laboratory data where liquid limit values were determined using only percussion (dynamic) or falling cone (static) methods. [ABSTRACT FROM AUTHOR]

An enormous variation in light, both temporally and spatially, exists in tropical forests, which represents a potential driver for plant physiological plasticity. The physiological plasticity of epiphytic orchids from two tropical dry forests in response to different light environments was experimentally investigated. Plants of five species were growing in a shade-house under three different light regimes (photosynthetic photon flux density; PPFD of 20, 50 and 70% of total daily incident radiation) under watered and drought conditions. Orchids with similar leaf morphology but from different forests responded differently to the same light environment. Linear leaves of Encyclia nematocaulon avoided drought stress through stomata control and had a notable increase of photosynthesis, lower osmotic potential, and high photosynthetic efficiency under 50% daily PPFD during both drought and watered periods. In contrast, orchids with cylindrical and oval leaves had a marked decrease of these physiological parameters under 50 and 70% of PPFD during the drought period, but then recovered after rewatering. Oval leaves of Lophiaris oerstedii were more sensitive to high light and water availability because they had a strong decrease of their physiological parameters at 70% of PPFD, even during the rewatering period. Contrary to our predictions, E. nematocaulon had low plasticity and Laelia rubescens , from the deciduous forest, was the most able to acclimate. In general, orchids from the drier forest had higher plasticity than those from the more humid forest, which might help them to tolerate the higher fluctuations of light and water availability that occur there. [ABSTRACT FROM AUTHOR]

Among the multitude of alternate plasticity index (PI) estimation proposals, empirical correlations based on the linear shrinkage (LS) test, originally proposed in the 1967 edition of the British BS 1377 standard, seem to be gaining increased attention. This study has two main aims: (i) re-examining LS-based correlations for PI estimation to better understand their true potentials and/or limitations; and (ii) investigating the possibility of employing LS, as a proxy for the standard PI, for fine-grained soil classification. To this end, comprehensive statistical analyses were performed on the largest and most diverse database assembled of its kind, entailing PI:LS measurements for 265 different fine-grained soils [pertaining to the 'soft' base percussion-cup liquid limit (LL = 17–134%) and the Australian standard LS = 0.5–32.0%]. It was demonstrated that the LS can generally only provide a rough approximation of the actual PI. At best, only those predictions produced by PI = 1.86 × LS for low-plasticity soils (i.e., LL ≤ 35%) included in the database may be deemed acceptable, specifically when difficulties are encountered in executing the standard plastic limit (PL) thread-rolling test for such soils. The second/novel aim of this study found that the agreement level between the Casagrande-style plasticity-chart classification (based on the measured PI = LL − PL) and that performed using the PI deduced from a newly introduced multivariable correlation involving LS and LL, as inputs, was obtained as 95%. Hence, in the absence of measured PI, the multivariable PI:LS:LL correlation may be deemed suitable for preliminary soil classification purposes. • Examine linear shrinkage (LS) – liquid limit (LL) correlations for plasticity index (PI) estimates. • Statistical analysis of large PI:LS database for 265 different fine-grained soils with measured PL. • LS can generally only provide guesstimate of actual PI [= LL − thread-rolling plastic limit (PL)]. • For low-plasticity soils (i.e., LL ≤ 35%), predictions by PI = 1.86 × LS may be deemed acceptable. • New multivariable PI:LS:LL correlation deemed suitable for preliminary soil classification purposes. [ABSTRACT FROM AUTHOR]

Expansive soil is the soil whose volume changes according to the changing of moisture content included in it. When the soil absorbs water this will lead to an increase in its volume and vice-versa. The swelling of soil leads to structural damage such as kerbs swelling, cracking in borders and reinforced foundation, and finally leads to deformation in floors and doors, these deformations may be light, moderate, and heavy according to the value of swelling. In this research, the expansive soil "that is brought from Karkuke province" has an initial plasticity index (P.I) is (98), Liquid limit (L.L) is (163), and plastic limit (P.L) is (65). In order to improve the properties of expansive soil, petroleum products have been added to the soil in different percentages (2%, 4%, 6%, 8%, and 10%) by soil weight. These different products such as Kerosene, Gasoil, and Cut-back asphalt (MC-30) are brought from AL-Durra Oil Refinery in Baghdad.. After done all the laboratory tests on this type of soil with different percentages of adding petroleum products, it will be noted that the addition of 10% by soil weight of kerosene reduces the liquid limit (L.L), plastic limit (P.L), and plasticity index (P.I). It also reduces the free swell and swelling pressure as shown in this research. For all petroleum products, the increase in adding petroleum products leads to reduce volumetric changes.

The morphological, anatomical and biochemical traits of the leaves of yellow foxglove (Digitalis grandiflora Mill.) from two microhabitats, forest interior (full shade under oak canopy) and forest edge (half shade near shrubs), were studied. The microhabitats differed in the mean levels of available light, but did not differ in soil moisture. The mean level of light in the forest edge microhabitat was significantly higher than in the forest interior. Multivariate ANOVA was used to test the effects of microhabitat. Comparison of the available light with soil moisture revealed that both factors significantly influenced the morphological and anatomical variables of D. grandiflora. Leaf area, mass, leaf mass per area (LMA), surface area per unit dry mass (SLA), density and thickness varied greatly between leaves exposed to different light regimes. Leaves that developed in the shade were larger and thinner and had a greater SLA than those that developed in the half shade. In contrast, at higher light irradiances, at the forest edge, leaves tended to be thicker, with higher LMA and density. Stomatal density was higher in the half-shade leaves than in the full-shade ones. LMA was correlated with leaf area and mass and to a lesser extent with thickness and density in the forest edge microsite. The considerable variations in leaf density and thickness recorded here confirm the very high variation in cell size and amounts of structural tissue within species. The leaf plasticity index (PI) was the highest for the morphological leaf traits as compared to the anatomical and biochemical ones. The nitrogen content was higher in the “half-shade leaves” than in the “shade leaves”. Denser leaves corresponded to lower nitrogen (N) contents. The leaves of plants from the forest edge had more potassium (K) than leaves of plants from the forest interior on an area basis but not on a dry mass basis; the reverse was true for phosphorus.

Dynamic properties namely shear modulus (G) and damping (h) are input parameters for predicting the ground response of natural soil deposits. The dynamic properties of sands and clays are dependent on many factors such as void ratio, confining pressure, strain amplitude, morphology, and plasticity characteristics. Considerable research has been reported in the recent past by Seed and Idriss (Soil moduli and damping factors for dynamic response analysis, 1970), Hardin and Drnevich (J Soil Mech Found Div ASCE 98(7):667-692, 1972); Seed and Idriss (Ground motions and soil liquefaction during earthquakes. Earthquake Engineering Research Institute, Berkeley 1982), Vucetic and Dobry (J Geotech Eng Div ASCE 117(1):89-107, 1991) and many others on dynamic properties of sands and clays. The factors affecting the dynamic properties of sands and clays are well documented, but soils generally, occur as mixtures of sand, silt and clay in various proportions. There is very little effort made in understanding the dynamic behavior of sand-fines mixtures and therefore there is a need to investigate the dynamic properties of sand-fines mixtures. In the present paper, the results of the behavior of sand-fines mixtures under cyclic loads are discussed. The experimental program consisted of a series of cyclic triaxial shear tests conducted as per ASTM D 3999 (Standard Test Methods for Determination of the Modulus and Damping properties of soils Using the cyclic Triaxial Apparatus. American Society for Testing and Materials 1991) to investigate the strain dependent shear modulus and damping of sand-fines mixtures of different plasticity. Sand was obtained from the Sabarmati river and three types of locally available fines i.e. low-plastic, medium- plastic and bentonite fines were used. Fines content was varied from 15 to 60%. The effect of fines content, plasticity, and relative density on shear modulus and damping is reported. Shear modulus at 0.005% strain level correlates well with the plasticity index for sand-fines mixtures of low to medium plasticity i.e. 0 < IP < 40. [ABSTRACT FROM AUTHOR]

Carbon dioxide concentration and light conditions may greatly vary between mountainous and lowland areas determining the photosynthetic performance of plants species. This paper aimed to evaluate the photosynthetic responses of Lotus corniculatus, growing in a mountain and a lowland grassland, under low and high radiation and CO concentration. Net photosynthetic rate, stomatal conductance, transpiration rate, and intercellular CO concentration were measured while the water-use efficiency and the ratio of variable to maximal fluorescence were calculated. Photosynthetic response curves to different levels of radiation and intercellular CO partial pressure were estimated. Our results showed that high radiation and CO concentration enhanced water-use efficiency of plants at both sites, enabling them to use more efficiently the available water reserves under drought conditions. The increase of radiation and CO concentration would enhance the photosynthetic performance of the mountainous population of L. corniculatus, which overall seems to express higher phenotypic plasticity. [ABSTRACT FROM AUTHOR]

This study deals with the effect of salinity of groundwater on some properties of clayey soil. Properties obtained from tests carried out on samples mixed with water containing different salt contents are compared with those obtained from tests carried out on samples mixed with pure water (tap water). The tested samples were taken from the site of the Faculty of Engineering in Qena, South Valley University. Two sets of samples of the clay soil were tested. One was mixed with pure water (pure water clay soil) and the other was mixed with salty water added to it in ratios ranging from 20% to 80% (clay soil mixed with salt). The test results showed the effect of groundwater salinity on the tested samples. The plasticity index decreased from 26 for pure water clay soil to 24.96 for clay soil mixed with 80% salt. The coefficient of consolidation increased from 0.00196 for pure water clay soil to 0.002744 for clay soil mixed with 80% salt. The California bearing ratio increased from 9.75% for pure water clay soil to 10.15% for clay soil mixed with 80% salt. The optimum moisture content increased from 14.25% for pure water clay soil to 16.5% for clay soil mixed with 100% salt. Decrease in the maximum dry density is observed for clay soil mixed with salty when compared with pure water clay soil. A marked decrease was noticed for the value of the unconfined compressive strength. All the tests were carried out in the Soil Mechanics and Foundations Lab, Faculty of Engineering in Qena, South Valley University. [ABSTRACT FROM AUTHOR]

Yielded specimens have various deformation patterns depending on loading stages and stress ratios in spite of the same geomaterials (e.g. soils and soft-sediment). Failure patterns of materials bifurcationally change to diamond, bulge and a pair of oblique shear patterns. Symmetry of deformation patterns (e.g. shear band patterns) has been illuminated by bifurcation analysis of governing equation based on Cam-clay model. Plasticity index tested by Casagrande liquid limit device and plastic limit instruments is known to describe mechanical characteristics (e.g. compressibility) of soils. Relationship between plasticity index and mechanical bifurcation controls the evolution of deformation patterns. From the view point of concept of plastic potential, we show that plasticity index theoretically determines deformation patterns of soils on the basis of the bifurcation analysis. Furthermore, because deformation facies of rocks are described by mean ductility of rocks similar to the concept of plasticity index, we point out that mean ductility controls mechanical bifurcation of the geologic materials such as soft-sediments. [ABSTRACT FROM AUTHOR]

An estimation method for earthquake-induced pore water pressure and the post-earthquake settlement of soft clay was developed by focusing on its Atterberg's limits and the direction of cyclic shearing. To clarify the fundamental characteristics of clays with different Atterberg's limits under multi-directional cyclic shear, normally consolidated specimens of Kaolinite clay, Tokyo bay clay and Kitakyushu clay were subjected to cyclic simple shear under the undrained condition with various cyclic shear directions and shear strain amplitudes, followed by the dissipation of cyclic shear-induced pore water pressure. The effects of undrained cyclic shear on the pore water pressure accumulation and post-cyclic settlement were observed, and relationships with Atterberg's limits were then investigated. In conclusion, the pore water pressure accumulation and post-cyclic settlement induced by multi-directional cyclic shear increase considerably to a higher level compared with those generated by the uni-directional one and such a tendency is evident for clays with a wide range of Atterberg's limits. Comparisons of the results indicate that the soil with higher plasticity index shows the lower pore water pressure accumulation and post-cyclic settlement, irrespective of number of strain cycles and shear strain amplitude. Based on these results, a model for earthquake-induced pore water pressure and post-earthquake settlement was developed by incorporating the Atterberg's limits as a function of experimental constants and the practical applicability was confirmed. [ABSTRACT FROM AUTHOR]

This paper presents the method of plasticity index calculation of isotropic two-process surfaces on the basis of index developed by Greenwood and Williamson for random surfaces of Gaussian ordinate distribution. This method was applied to computer generated isotropic two-process textures. The proposed plasticity index of two-process surface was compared with that of plateau surface and of the whole surface calculated by traditional manner. It was shown that plasticity index and generally the contact properties of two-process surfaces depended not only on plateau but also in a smaller degree on valley roughness. The method of estimation of summit radius of plateau surface from the analysis of two-process surface was presented too. [ABSTRACT FROM AUTHOR]

Plastic responses in plants can be induced by spatial heterogeneity, being the restinga a supportive ecosystem to understand these responses due to its limiting environmental conditions. This study evaluated so compared the leaf plastic responses in two populations of Tibouchina clavata (Melastomataceae) inhabiting the herbaceous and forest formations of the restinga Acaraí State Park, located in São Francisco do Sul-SC. In the ten individuals sample of each formation were measured leaf morphoanatomic attributes and stem. Environmental variables such as edaphic nutrition, gravimetric moisture and light radiation were measured. Mean values for each variable were compared by the Student t test. For each attribute, it was calculated phenotypic plasticity index. Morphological and anatomical attributes differentiate the two populations together, and the population of herbaceous formation typically xeromorphic due to more stringent environmental conditions. More favorable terms given by the increased supply of nutrients and water in the forest environment provided greater investment of growing individuals. Anatomical attributes were shown little plastic when compared to the morphological. T. clavata it proved to be a morphologically plastic kind that allows the understanding of the effects of the limiting factors of the restinga on plant development, with emphasis on nutrition, water and luminous conditions that induce xeromorphism. [ABSTRACT FROM AUTHOR]

A Prediction is a vital tool in engineering used to take right decisions. Therefore, it is very important for engineers to quickly predict the behavior of geomaterials used in the infrastructures. California Bearing Ratio (CBR) test is a common laboratory test, performed to evaluate the shear strength and stiffness modulus of sub grade for the design of pavement. CBR test is a laborious test, therefore, it is vital to develop the models for quick assessment of CBR value. This study is an attempt to develop valid models to determine the CBR value from index properties of soil which are quicker to estimate from their standard method of testing. In this study authors developed predictive models using 59 set of soil samples containing both fine grained and coarse grained soil samples. Three models were developed and validity of these models was checked on 25 set of soil samples tested separately. Authors developed separate models for coarse grained soil and fine grained soils. These models were developed, based on liquid limit and plasticity index for fine grained soil, the coefficient of uniformity and maximum dry density for coarse grained soil. [ABSTRACT FROM AUTHOR]

Atterberg limits and indices, for example liquid limit ( LL), plastic limit ( PL), linear shrinkage ( LS) and plasticity index ( PI), are important soil properties in engineering and land evaluation for predicting soil mechanical behaviour. This study was conducted to develop and evaluate pedotransfer functions ( PTFs) to predict Atterberg limits using measured and morphological soil properties from a large data set in South Africa covering a vast range of soils, geologies and climates. Five PTFs were developed; the first four using measured properties from 2330 soil horizons including extractable Fe, Al, Mn, Na, K, Mg and Ca; organic carbon ( OC); pH (H2O); cation exchange capacity ( CEC); and sand, silt and clay fractions to predict LL, PL, LS and PI. Morphological descriptors such as colour, structure (grade, size and type), consistency, occurrence of slickensides and cutans and abundance of roots were included in the second PTF using data from 717 horizons to predict PI. For all PTFs, two-thirds of the data were randomly selected and used for model development and the remainder for validation. Prediction accuracies of R2 between 0.49 and 0.77 comparable to other studies on large data sets but underperformed when compared to localized data sets. For engineering purposes, site-specific PTFs for prediction of Atterberg limits should be developed. [ABSTRACT FROM AUTHOR]