Slopes Of Hillocks Research Articles

RESEARCHES THAT CONCERN SOME PHYSIOLOGICAL, BIOLOGICAL AND CHEMICAL ISSUES BY NOW RECORDED IN THE CASES OF SOME VINE KINDS DESTINED TO PRODUCE TABLE GRAPES WHICH ARE CURRENTLY CULTIVATED WITHIN THE DRĂGĂȘANI VINEYARD

The productiveness performance ratios of the vine kinds destined to produce grapes for fresh status consumption insofar their respective quantities and quality levels could ever be concerned are effectively influenced by the vine log’s leaves’active surface and by its own intrinsic features as these latters could be evaluated through the analyses performed upon the leaves’respectively gained amounts of various macro-elements. In the cases of certain vine kinds such as for example Victoria, Chasselas Doré, Călina, Hamburg Muscat and Afuz Ali the performed investigations have brought up reliable evidence which does concern the existences of their respective vocations for revaluating at their best the pedologic and oeno-climate-related local circumstances graciously offered by this longtime since well-known vine cultivated area. Among these circumstances does as well figure the humanly chosen situation of the concerned vine logs through their precisely calculated positions upon the local hillock’slopes. For all of the hereby studied vine kinds the effective extents of their respective leaves’active surfaces as well as their own intrinsic features are really submitted to the influences which could be exerted by the most highly possible to occur drought time intervals. Under these circumstances the vine logs situated amidst the hillock slope should benefit from the most intense photo-synthesis processes while the greatest respiration capacities could be recorded at the vine logs situated upon the slope’s top. However the intensity degrees attended to by the transpiration processes would instead be the highest for the vine logs situated at the slopes’feet.

Improving geotechnical properties of soil of hillock slope using crushed recycled concrete aggregates

With the massive expansion of urbanization worldwide, a huge volume of construction and demolition waste (CDW) generation has become a common issue along with CDW from controlled demolition and earthquakes, which causes a tremendous headache for environmentalists. Moreover, sliding and failure of the slope of hillocks, hills, roads, and earthen dams raise concerns for geotechnical engineers. Among the several methods of improving the geotechnical behaviour of soil of the slopes, this research utilized CDW-based recycled concrete aggregates (RCA) to improve slopes of two hillocks named GK and BH. The crushed RCA was applied in various percentages, 5–35 %, in the soil mass and as a circular column to observe the improvement of the soil's geotechnical properties that largely influence slope stability. RCA column, a sustainable alternative to the sand, stone, or other natural materials column, can work as a vertical drain with an improved permeability of slope geo-material to improve infiltration. The soil samples with 30 % RCA mixed and RCA columns inserted into the soil mass resulted in lower consolidation settlement, compressibility index, and higher shear strength parameters. Moreover, 30 % RCA column increased the permeability by 6 and 7-times for the hillocks GK and BH, respectively, which reduces the chance of excess pore water pressure (PWP) development that can trigger the failure of a slope. Improving soil properties with recycled concrete aggregates can be a sustainable way to solve weak soil and failure issues of low-permeable low-height natural hillocks.

Новый класс галофитных растительных сообществ на территории России (Climacopteretea crassae Akhani 2004 ex Świerszcz et al. 2021)

We argue the presence in the delta of the Volga River of a new class of desert halophyte communities Climacopteretea crassae Akhani 2004 ex Świerszcz et al. 2021. This class was originally presented by H. Akhani (2004) as a syntaxon uniting plant communities with a predominance of annual succulent plants with C4 photosynthesis in Iran. The class was proposed previously, without specifying the nomenclature type. In 2021, the class Climacopteretea crassae was validated (Świerszcz et al., 2021). S. Świerszcz and his co-authors gave the class a floristic and ecological characterization. The syntaxa of this class remind such of the class Therosalicornietea Tx in Tx. et Oberd. 1958 in terms of the high representation of annual species of the Chenopodiaceae family (although with the participation of perennial species). However, they cannot be called the pioneer communities that usually characterize communities of the class Therosalicornietea. Compared to communities Therosalicornietea they occupy drier habitats. In addition to the strong salinization of the soil, from the surface they can also be solonetzic. Typically, habitats of the class Climacopteretea crassae are significantly affected by grazing by farm animals. The order Psylliostachyetalia spicato-leptostachyae Świerszcz et al. 2021 and the alliance Climacopterion lanatae Berdyev et Golub in Golub 1995 were assigned to the class Climacopteretea crassae. We proposed a new alliance Petrosimonion oppositifoliae all. nova in the order Psylliostachyetalia spicato-leptostachyae. The ass. Suaedo-Petrosimonietum Golub 1986 was placed in this alliance. This association was originally included in the class Glycyrrhizetea glabrae Golub et Mirkinin Golub 1995 (Golub and Mirkin, 1986; Golub, 1986), and later in Therosalicornietea R. Tx. in R. Tx. et Oberdorfer 1958 (Golub, 1995; Golub and Maltsev, 2013). Plant communities of this association are found in the delta of the Volga River in dry habitats, mainly located on the slopes of Baer hillocks and their foots with a deep level of groundwater. The soils are highly saline and solonetzic. Above the habitats occupied by ass. Suaedo-Petrosimonietum, along the slopes of Baer hills and on their tops, zonal communities of class Artemisietea lerchianae Golub 1994 occur. Various meadow and halophytic plant communities grow below this association. New alliance Petrosimonion oppositifoliae all. nova was suggested. We suppose that further study of the desert halophytic vegetation of the Caspian Lowland will allow to establish other syntaxa of class Climacopteretea crassae on this territory. Thus, in our opinion, the non-ranking plant communities of Petrosimonia oppositifolia–Suaeda acuminata comm., Suaeda altissima–Suaedaa cuminata comm., Suaeda tragus–Suaeda acuminata comm., occurring in this lowland, including Russia are closely related to this class (Freitag et al., 2001). In addition, a new class of halophyte communities separate from Climacopteretea crassae should be established for this territory on automorphic and similar soils, the floristic composition of which differs significantly from the phytocenoses of hydromorphic soils, such as those belonging to class Therosalicornietea Tx. in Tx. et Oberd. 1958. But the consideration of this issue requires further study of the vegetation of the Caspian lowland and the territories adjacent to it.

Растительные сообщества песчаного массива Сарыкум (Республика Дагестан)

Растительные сообщества песчаного массива Сарыкум (Республика Дагестан)

Growth of faces of K2CoxNi1 – x(SO4)2 · 6H2O mixed crystals

Data on the morphology and normal growth rate of the (110) and (001) faces, velocities of step motion, and slopes of dislocation hillocks on the (001) face of K2Co x Ni1– x (SO4)2 · 6H2O crystals at different supersaturations of solutions with a Co/Ni ratio equal to 1: 1 or 1: 2 have been obtained using a Michelson interferometer. The morphology of the (110) faces is found to be the same for solutions of both compositions. Powerful dislocation sources with large Burgers vectors dominate on the (001) face. The morphology of the (001) surface is rougher than that of (110), especially in a 1: 2 solution at high supersaturation. The (110) faces grow more slowly as compared with (001). The kinetic coefficients of steps on the (001) face are identical in the 1: 1 and 1: 2 solutions. The influence of the kinetic and morphological characteristics of (001) faces on the single-crystal quality is analyzed.

Colêmbolos e fungos micorrízicos arbusculares como indicadores de degradação em fragmentos florestais de encosta

Fragmented forests is the dominant environment in the tropical landscape, and to the success of any conservation and recovery, it is necessary to evaluate and interpret the degree of degradation of these fragments. Thus, the objective of this study is to evaluate the springtails epigean and mycorrhizal fungi as indicators of degradation in forest fragments slopes of hillocks. The study was conducted in four forest fragments in the basins of rivers Macacu and Caceribu, Itaborai (RJ). As forest fragments are in hillocks, collections were made in the upper, middle and lower thirds, in dry and wet seasons of year. The community of springtails and AMF used as indicators of degradation, even occupying different vertical soil strata, converged directly and indirectly to the same end, pointing the P1 as the most conserved among forest fragments analyzed and the potential to be used as reference designs recovery of degraded areas.

Effect of supersaturation on hillock of directional Growth of KDP crystals.

KDP single crystals were grown in aqueous solution by using “point seeds” with a defined crystallographic direction of 59° to the Z axis. When hillock slopes on the (100) face of KDP crystals were measured within the supersaturation (σ) range of 0 < σ ≤ 0.06, the slope of hillocks with hollow cores depended nonlinearly on supersaturation. Below σ = 0.02, the hillock slope depended on supersaturation, but when σ was ≥ 0.02, the hillock slope increased more gradually and was less dependent on supersaturation. Hollow funnel-shaped growth dislocation on the (100) face of KDP crystals was observed at σ = 0.04, characterized by large holes with micro-steps and step bunching inside, the formation of which were analyzed. The result verified that the reversed growth appears to occur within hollow channels found on growth hillocks.

Influence of In on the surface morphology of HVPE grown GaN

In this paper, a study is presented on the effect of In on the surface morphology of GaN grown by HVPE. Experiments are performed with N 2 and H 2 as the carrier gasses, both with and without In present in the reactor. The adding of In increases the morphological quality of the grown layers; this effect is most strongly observed for N 2 as the carrier gas. It is found that adding In reduces the growth rate and also increases the steepness of the growth hillocks on the surface. The step velocity, which is calculated from hillock slopes and the growth rate, decreases upon adding In. Without In, trails are visible across the surface where steps are distorted by passing a dislocation outcrop. With In present this pinning is still present, however, the trails do not form. Two possible explanations for this phenomenon are an increased surface diffusion due to a mono- or bi-layer of In on the surface and the slower step motion when In is present.

Is Crystal Growth under Low Supersaturations Influenced by a Tendency to a Minimum of the Surface‐Free Energy?

The long-standing problem of face morphology is discussed. Special emphasis is put on macroscopically flat faces, whose growth, under low supersaturations, is driven by dislocations possessing some screw component. The most general case, where the crystal face is pierced by more than one screw dislocation, is considered. If performed under sufficiently low supersaturation, the growth leads to the formation of the face morphology corresponding to the minimum of the surface-free energy. The thermodynamic driving force for face flattening is the difference in the surface-free energy of the vicinal faces of the hillocks (emanating from screw dislocations) and that of a singular face, which can truncate the valley between the growth hillocks. The hillock slope gives the quantitative relation between energetics and kinetics. The result of the considerations is that the lower the supersaturation, the more important is the role of the surface-free energy in face flattening. Another factor, particularly under sufficiently low supersaturations, is the effective increase in the local supersaturation at the valley separating two growth hillocks. The reason is that the dislocation strain energy vanishes there. (This is most evident when two dislocations of opposite sign are considered.) Besides, the valley floors are concave regions on the crystal surface, where the building blocks are bound more strongly. Thus, the kinetic reason for face flattening is the relative preference for incorporation of atoms, arriving from the ambient phase, at the valley floor. Note that accelerated step annihilation in the valley floor should be a universal factor, which favors face flattening under any supersaturation. The amount of flattening in the growth situation is determined by the interplay between supersaturation and thermodynamics.

Effect of temperature and supersaturation on the growth of Sr(No 3) 2 (1 1 1) face in aqueous solution

The normal growth rate R , hillock slope p and step velocity v = R / p of spiral growth hillocks on the (1 1 1) face of a Sr(NO 3) 2 crystal growing in aqueous solutions were measured as a function of supersaturation σ for various growth temperatures T g by in situ Michelson interferometry. At given temperatures, p and v increased linearly with σ and, thus, R was proportional to σ 2 in the supersaturation range σ = 0.40 – 3.0 % . Based on these data, the step free energy α s and the step kinetic coefficient β s were calculated. In the temperature range T g = 10.5 – 37.3 ° C , the step free energy was almost constant. By assuming that growth hillocks consist of single-, double- and triple-arm spiral steps, the values of step free energy were estimated to be α s = 4.0 , 8.0 and 12 mJ/m 2 , respectively. Meanwhile, the coefficient β s increased exponentially with temperature. An Arrhenius plot showed a linear dependence of ln β s on 1 / T g in the temperature range studied, from which the activation energy of step advance was estimated as E = 53 kJ / mol .

Single-Molecule Orientations in Dyed Salt Crystals

We present single-molecule confocal microscopy studies of orientational distributions for luminophores isolated in potassium hydrogen phthalate (KAP) crystals. The incorporation of dye molecules that bear no size or shape similarity to the host ions is observed, demonstrating that single-molecule studies on mixed crystals need not be restricted to isomorphous host/guest pairs. Violamine R is oriented and overgrown by the fast vicinal slopes of growth hillocks within the symmetry-related {010} growth sectors and DCM deposits in the {11} growth sectors of KAP. Both mixed crystals exhibit modest absorption dichroism relative to basic pyranine-doped K(2)SO(4). The latter was studied to ensure that a range of orientations was sampled in our experiments. Average orientations determined at the single-molecule level were in close agreement to ensemble-averaged measurements for all three systems, and the chromophore orientational distributions were broader than anticipated, indicating that the crystals incorporate guest molecules in a range of orientations outside the measured ensemble average.

In situ interferometric investigation of hillock morphology of the {100} and {101} faces of KDP growing in TMS gels

AbstractThe results of an in situ interferometric study of the surface morphology of {100} and {101} faces of potassium dihydrogen phosphate (KDP) crystals growing in the tetramethoxysilane gel are described and discussed. It was observed that: (a) in the case of crystal growth in gel both slopes of hillocks and surface kinetic coefficient are smaller than in solution growth, (b) for low supersaturations face growth rate linearly depends on bulk supersaturation and the structure of growth centers depends on the supersaturation and growth rate, and (c) for high supersaturations polyhedral instability appears. Supersaturation threshold for transition to polyhedral instability was estimated and formation of gel inclusions is discussed. (© 2005 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

AFM investigation of step kinetics and hillock morphology of the {1 0 0} face of KDP

Step velocities and hillock slopes on the {1 0 0} face of KDP were measured over a supersaturation range of 0< σ<0.15, where σ is the supersaturation. The formation of macrosteps and their evolution with distance from the hillock top were also observed. Hillock slope depended linearly on supersaturation and hillock geometry. The two non-equivalent sectors exhibited different slopes and step velocities. AFM shows an elementary step height of 3.7 Å, or half the unit cell height, whereas previous interferometric experiments assumed the elementary step was a unit cell. Values of the step edge energy ( α), the kinetic coefficients for the slow and fast directions ( β S and β F), and the activation energies for slow and fast step motion ( E a,S and E a,F) were calculated to be 24.0 erg/cm 2, 0.071 cm/s, 0.206 cm/s, 0.26 eV/molecule, and 0.21 eV/molecule, respectively. Analysis of macrostep evolution including the dependence of step height on time and terrace width on distance were performed and compared to predictions of published models. The results do not allow us to distinguish between a shock wave model and a continuous step-doubling model. Analysis within the latter model leads to a characteristic adsorption time for impurities ( λ −1) of 0.0716 s.

Growth kinetics of primary and secondary solid phases in Sr(NO 3)–H 2O peritectic system

The growth behavior of the primary α phase (Sr(NO 3) 2) and the secondary β phase (Sr(NO 3) 2·4H 2O) in Sr(NO 3) 2–H 2O peritectic system was observed in situ in a solution flow system. The two phases grew simultaneously below the peritectic temperature in the solution with the composition near the peritectic point. The β phase grew much faster than the α phase due to the difference in both supersaturation and kinetic property for two phases. This resulted in the peritectic structure that the β phase engulfed the α phase. Using Michelson interferometry, growth rate was measured on the most widely developed faces, the (1 1 1) face of the α phase and the (1 1 0) face of the β phase. The β phase had the larger growth rate and step velocity and the smaller hillock slope than the α phase at a given supersaturation. The kinetic coefficient β s and the edge free energy α s of steps were evaluated as follows: β s=5.1×10 −2 cm/s and α s=3.6 mJ/m 2 for the α phase; β s=5.3×10 −1 cm/s and α s=18 mJ/m 2 for the β phase. This indicates that the step kinetics influences the growth of the two phases more significantly than that of the surface energy of step edge.

Formation of small straight steps among large rough steps on the {1 1 0} face of cadmium mercury thiocyanate crystal

Rough steps generated by dislocation sources are very often observed on the {1 1 0} faces of cadmium mercury thiocyanate crystal, which is believed to result from the complex solution structures and the various growth units incorporated into the crystal lattice. Among these large rough steps, some small straight steps perpendicular to the [1 1 3 ̄ ] direction are formed. The heights of the straight steps vary from 1.6 up to 8.1 nm, most of which are multiples of the elementary step height (0.81 nm). Below each small step, there exists a hole where some impurities are adsorbed. The striking feature of these small straight steps is that they are formed by bunching of part of the rough steps, which is quite different from the usual step bunches. The occurrence of these straight steps is closely related to the slopes of growth hillocks, which is explained by the BCF theory.

Arsenic pressure dependence of hillock morphology on GaAs ( n 1 1)A substrates grown using MBE

Surface morphology of hillocks on the surface of various orientations of a GaAs substrate was observed by an atomic force microscope (AFM). Only (1 1 1)A and (2 1 1)A substrates formed pyramidal hillocks. The surfaces were the top layers of seven-period asymmetric double quantum wells or the buffer layer, and the Ga flux and substrate temperature were kept constant at 0.76 ML/s and 520°C, respectively. With increasing As pressure from 7.6 ML/s (beam equivalent pressure, BEP; 9.0×10 −6 Torr) to 32 ML/s (BPE; 4.5×10 −5 Torr), the hillock heights and slopes on (1 1 1)A first increased and then decreased at the highest pressures. The decrease in slope was large: at an As pressure of 1.95×10 −5 Torr, the hillock slope on (1 1 1)A was about 0.8°, whereas at 2.85×10 −5 Torr, the slopes were usually less than 0.3°. This reduction of the height and slope at higher As pressure is explained by the decreasing of the super-saturation of GaAs species in a quasi-liquid layer, QLL of As due to increment of Ga desorption.

Kinetics of calcite growth: surface processes and relationships to macroscopic rate laws

This study links classical crystal growth theory with observations of microscopic surface processes to quantify the dependence of calcite growth on supersaturation, σ, and show relationships to the same dependencies often approximated by affinity based expressions. In situ Atomic Force Microscopy was used to quantify calcite growth rates and observe transitions in growth processes on {10 1 4} faces in characterized solutions with variable σ. When σ < 0.8, growth occurs by step flow at surface defects, including screw dislocations. As σ exceeds 0.8, two-dimensional surface nucleation becomes increasingly important. The single sourced, single spirals that are produced at lower σ were examined to measure rates of step flow and the slopes of growth hillocks. These data were used to obtain the surface-normal growth rate, R m , by the pure spiral mechanism. The dependence of overall growth rate upon dislocation source structure was analyzed using the fundamentals of crystal growth theory. The resulting surface process-based rate expressions for spiral growth show the relationships between R m and the distribution and structures of dislocation sources. These theoretical relations are upheld by the process-based experimental rate data reported in this study. The analysis further shows that the dependence of growth rate on dislocation source structures is essential for properly representing growth. This is because most growth sources exhibit complex structures with multiple dislocations. The expressions resulting from this analysis were compared to affinity-based rate equations to show where popular affinity-based rate laws hold or break down. Results of this study demonstrate that the widely used second order chemical affinity-based rate laws are physically meaningful only under special conditions. The exponent in affinity-based expressions is dependent upon the supersaturation range used to fit data. An apparent second order dependence is achieved when solution supersaturations are very near equilibrium and growth occurs only by simple, single sourced dislocation spirals. These findings indicate the need to apply caution when deducing growth mechanisms and rate laws from temporal changes in bulk solution chemistry. Observations of various types of surface defects that give rise to step formation suggest that popular ‘rate laws’ are sample-dependent composites of rate contributions from each dislocation structure.

Elementary growth mechanism of dipyramid ADP face

Abstract Michelson interferometry combined with X-ray topography were applied to study growth morphology and kinetics of the (101) ADP face in the temperature interval 29-67°C. A formula giving the azimuthally anisotropic hillock slope vs. supersaturation on a complex dislocation source plus experimental dependencies of the hillock slope on the supersaturation for various dislocation sources enabled us to determine the free surface energy of the step riser α = 29 erg/cm2 and the Burgers' vector of the growth sources. The data reveal a step-step interaction at average distances of the order ∼1 μm. This interaction is interpreted in the terms of surface diffusion. The effective activation energy for step propagation was 65 kJ/mol for T 40°C. The anisitropy of the growth features is connected to the crystal structure through the “jump” distance in different directions.

Elementary growth kinetics of silver electrocrystallization

The elementary processes of electrochemical growth of cubic faces of silver single crystals were investigated after the so-called capillary method by means of in situ laser Michelson interferometry. Data were obtained about the motion of dislocation generated steps during electrocrystallization from a stagnant solution. It was proved that step motion proceeds after the direct incorporation mechanism, with bulk diffusion field overlap, leading to deviation from linearity in the step velocity/overvoltage dependence at higher hillock slopes. The true value of the step kinetic coefficient for the studied face was determined: β = 1.2 cm/s. In acidified solutions β is much smaller: β = 0.17 cm/s. Interferometric measurements of hillock slope versus overvoltage dependencies allowed us to determine the Burgers vectors of the leading growth dislocation sources. The free surface energy of the step riser was determined without any additional suppositions: for pH ≅ 5 it was 130 erg/cm 2 and for pH ≅ 1 it was 110 erg/cm 2.

Interstep interaction in solution growth; (101) ADP face

Michelson interferometry combined with X-ray topography was applied to study growth morphology and kinetics of the (101) ADP face in a flowing solution. Step velocity was measured as a function of different parameters. The data reveal a step-step interaction at average distances of the order of ≈ 1 μm. This interaction is interpreted in the terms of surface diffusion. Parameters of step motion and adsorption on the surface are determined. Azimuthal growth anisotropy is related to crystal structure. A formula giving the azimuthally anisotropic hillock slope versus supersaturation on a complex dislocation source plus experimental dependencies of the hillock slope on the supersaturation for various dislocation sources enabled us to determine the free surface energy of the step riser α = 29 erg/cm 2 and the Burgers vector of the growth sources. “Quantization” of the measured hillock slopes in the whole supersaturation region supposes identical structure of the dislocation sources of equal strength.