Comparative LM, SEM and EDAX study of chalk glands on leaf and stem of two species of Plumbago Linn.

Stem and leaves of two species of PlumbagoLinn.viz. P. zeylanica Linn.andP. auriculata Lam. were investigated for the structure and chemical composition of chalk glands. Light Microscopy (LM) and Scanning Electron Microscopy (SEM) revealed the presence of chalk glands on both lower as well as upper surface of leaf and stem of both species. Chalk glands are abundant on lower surface and sparse on upper surface of leaf. Chalk glands are approximately hemispherical glands with oval or almost circular outline. It is composed of 8 cells arranged in two circles – central circle of 4 secretory cells and outer circle of 4 adjoining cells. Each secretory cell has depression which corresponds to pore. Each gland is surrounded by 4 subsidiary cells. No significant difference in the structure of chalk glands in both species was noticed. Chalk glands occupy three different positions with regard to epidermal cells –at the same level of the epidermis, slightly sunken in the epidermis and slightly raised above the epidermis. Common elements found in EDAX analysis of all chalk glands are carbon, oxygen, magnesium, sulphur, potassium and calcium. Differences in the presence of elements silicon, chlorine, aluminium, sodium, phosphorus were observed. The presence of significant amount of calcium in chalk glands and their dried deposits and absence of sodium and chlorine from dried deposits and even in some chalk glands appealed to use the term ‘Chalk gland’ instead of ‘Salt gland’ in Plumbago.

The Ring Rotation Illusion: Properties and Links of a Novel Illusion of Motion

We report a novel visual illusion we call the Ring Rotation Illusion (RRI). When a ring of stationary points replaces a circular outline, the ring of points appears to rotate to a halt, although no actual motion has been displayed. Three experiments evaluate the clarity of the illusory rotation. Clarity decreased as the diameter of the circle and ring increased and increased as the number of points forming the ring increased. The optimal interstimulus interval (ISI) between the circle and ring was 90 ms when stimulus presentations lasted 100 ms but 0 ms with 500 ms presentations. We compare the RRI to the Motion Bridging Effect (MBE), a similar illusion in which a stationary ring of points replaces an initial ring of points that spins so rapidly it looks like a stationary outline. A rotation of the stationary ring is seen that usually matches the direction of the initial ring’s invisible spin. Participants reported a slightly more frequent and clearer motion percept with the MBE than RRI. ISI manipulations had similar effects on the two illusions, but the effects of number of points and ring diameter were largely restricted to the RRI. We suggest that both the RRI and MBE motion percepts are produced by a visual heuristic that holds that the transition from an outline circle to a ring of points is plausibly explained by a rapid spin decelerating to a halt, but in the case of the MBE, an additional direction-sensitive mechanism contributes to this percept.

Description of a new marine predatory nematode Latronema dyngi sp. nov. (Nematoda, Chromadorida, Selachinematidae) from the west coast of Sweden and an updated phylogeny of Chromadoria

A new nematode species, Latronema dyngi sp. nov., is described from Skagerrak off the west coast of Sweden with the type locality near Dyngö island. Latronema dyngi sp. nov. is characterized by multispiral amphideal fovea with circular outline, 0.2–0.3 corresponding body diameters wide in males and 0.1–0.2 corresponding body diameters wide in females, 12 cuticular longitudinal ridges and 18–27 precloacal supplements in males. Latronema dyngi sp. nov. most closely resembles L. orcinum in terms of body length; demanian ratios a, b, c and c′; number of amphid turns in males; and the ratio of spicule length to cloacal body diameter. The two species can be differentiated by the number longitudinal ridges on the cuticle (12 for Latronema dyngi sp. nov. vs 20–22 for L. orcinum) and spicule length (65–78 μm for L. dyngi vs 60 for L. orcinum) and shape (weakly arcuate for L. dyngi sp. nov. vs strongly arcuate for L. orcinum). We also performed a maximum likelihood phylogenetic analysis on over 250 nematodes of the subclass Chromadoria based on their nearly full-length 18S rDNA sequences. In agreement with previous studies, our analysis supported Selachinematidae as a monophyletic group and placed Richtersia Steiner, 1916 within Desmodoridae Filipjev, 1922 or just outside of the main Desmodorida clade with the latter placement not well supported.

STATIC CALCULATION OF FILM ROOF OF CULTIVATION STRUCTURE

Membrane roofing greenhouses and small-scale farms are used in the spring and autumn period for growing various crops. The main load for such structures is wind. Norms of construction design of greenhouses do not contain provisions for calculating the membrane roof of cultivation structures for this type of load. For arched greenhouses with a circular outline of the coating, an approximate method for determining the forces from the wind load in a membrane stabilized by wind ropes is proposed. The membrane roof is considered as a soft cover under the influence of negative wind load. The calculated dependences for estimating the stress-strain state of the roof material are derived analytically. The calculation scheme of the roof deformed by wind pressure, corresponding to the actual operating conditions of the structure, is used to derive the dependencies. The roof of the structure is considered from the polyethylene membrane recommended by the building standards for the design of greenhouses, the physical and mechanical characteristics of which are standardized. Dependences are derived for determining the longitudinal and annular stresses in the roof material, the rational pitch of wind ropes and the maximum possible force in them. The proposed method of static calculation of the membrane roof can be used for cultivation structures with the outline of the coating close to circular

Cu–Al–Si alloy anode material with enhanced electrochemical properties for lithium ion batteries

The microstructure and electrochemical property of Cu–Al–Si alloy anode material are studied in this paper. The research shows that the alloy particle has a basic circular outline, and two copper-rich phases with different silicon contents are detected in the particle, and both phases with nanostructure are observed in its surface layer. The nano-silicon alloy negative electrode material needs to be used in a certain proportion with graphite, binder and conductive agent, and the stirring process also has an important influence on its electrochemical performance. Multiple mixing can achieve a better cycle retention compared to direct mixing. The first-cycle coulombic efficiency of the electrode material is improved up to about 90%, and the specific capacity is still higher than 500[Formula: see text]mAh[Formula: see text]g[Formula: see text] after 100 cycles. The battery manufacturing process is similar to the graphite negative electrode, so it is easy to be applied.

The emergence of the idea of a spherical sun in Greek science and philosophy

According to a standard idea of Greek science and philosophy, the shape of the sun is spherical. Such an idea appears already in Aristotle who offers, however, no good account for it, and only Stobaeus cites an authority, or rather collective authority, the Pythagoreans, for an early recognition of the idea in question. The ancient tradition left no direct evidence of how the sphericity of the sun was recognized, and the issue attracted very little attention in modern scholarship. I propose that in the late sixth century new empirical knowledge about the sun reached the Aegean and Italy. Some people who crossed the northern tropic repeatedly observed the sun from its ‘other’ side, for in the height of the summer an observer located south of the northern tropic saw the midday sun in the north. This made impossible Anaximander’s idea of the sun as a body containing fire and having one aperture and triggered a search for a better version. Since the sun invariably displayed a circular outline at any time, at any place and on all sides of the horizon, one had to consider the possibility that its shape was either spherical or ‘bowl-like’. The study of lunar light that led to the discovery of the sphericity of the moon was also helpful. The doctrine of a spherical sun was firmly established by the consensus of professional astronomers rather than due to an initiative by an outstanding thinker; however, one may think that Parmenides contributed to it. A spherical sun cannot be a sphere of fire – without a container, fire would have dispersed. This problem brought about a number of theories that treated the sun as a kind of mirror, etc. Further, a spherical sun that issues a reflected light was recognized to have been a solid and hence a heavy body, which contributed to approaching the spheres of the Sun, Moon and Earth in a similar way and making the Earth a planet.

IMAGE ANALYTICAL DETERMINATION OF THE SPHERULITE GROWTH IN POLYPROPYLENE COMPOSITES

Measuring the growth of spherulites in semi-crystalline thermoplastics helps to control and optimize industrial manufacturing processes of these materials. The growth can be observed in cross polarized images, taken at several time steps. The diameters of the spherulites are however measured manually in each step. Here, two approaches for replacing this tedious and time consuming method by automatic image analytic measurements are introduced. The first approach segments spherulites by finding salient 5x5 pixel patches in each time frame. Combining the information from all time frames into a 3D image yields the spherulites by a maximal flow graph cut in 3D. The growth is then measured by homography measurement. The second approach is closer to the manual method. Based on the Hough transform, spherulites are identified by their circular outline. The growth is then measured by comparing the radia of the least moving circles. The pros and cons of these methods are discussed based on synthetic image data as well as by comparison with manually measured growth rates.

Early post-embryonic development in Ellipsostrenua (Trilobita, Cambrian, Sweden) and the developmental patterns in Ellipsocephaloidea

This study documents the early post-embryonic developmental stages (protaspides and early meraspides) of the Cambrian trilobite Ellipsostrenua granulosa (Ahlberg, 1984) from the Gärdsjön Formation of Jämtland, Sweden. The early protaspid stage is characterized by a circular outline of the exoskeleton, two pairs of fixigenal spines, a short preglabellar field, a genal swelling, and prominent bacullae. The late protaspid stage differs only in having the trunk portion discernible. Early meraspid cranidia are sub-rectangular with prominent palpebral lobes, a wide anterior margin, a proportionally long anterior branch of the facial suture, and intergenal spines. Meraspid pygidia tentatively assigned to this species possess comparatively long macrospines. Small hypostomes associated with E. granulosa bear at least four pairs of marginal spines. A comparison of the early developmental stages of E. granulosa with some other species of Ellipsocephalidae and with species of the closely related Estaingiidae reveals several similarities. The conservative morphology of the early protaspid stage with only two pairs of fixigenal spines, the timing of the development of the trunk portion, and the presence of genal swellings and prominent bacullae could be phylogenetically informative. The range of size variation of the early protaspid stages in two families may be related either to taxonomical differences between Ellipsocephalidae and Estaingiidae, or to environmental differences in various paleogeographic settings.

GROUND OF PARAMETERS OF DISCRETISATION AT THE NUMERICAL ANALYSIS OF NON-CIRCULAR OUTLINE TUNNELS

Purpose. Influence on the strain-stress state of discretization of finite element model in the numerical analysis of non-circular outline tunnels is explored in the article. Methodology. For achievement of the put purpose, authors developed three finite element models of callote part at building of two-line railway tunnel. In each of models in a programmatic complex «Lira» was a concrete method of discretization area of cooperation with the temporal fastening. After creation of models, their numerical analysis with the detailed research of his results was conducted. Findings. The values of deformations and tensions of finite element models on horizontal and vertical axes, and also maximal values of moments and longitudinal forces in the temporal support are got. The comparative analysis of the got values is conducted. The graphs of conformities to the law of the indicated results from the features of discretization of two models are built. The third finite element model with the radial laying out of knots in the area of co-operation of the temporal fastening with the surrounding ground array is explored. Originality. It is set that at the numerical analysis of SSS of tunnel support of non-circular outline his results substantially depend on a form, sizes and configuration of the applied finite elements, from the sizes of calculation area of the ground massif, and also from the terms of his fixing (maximum terms). Practical value. The features of discretization and necessary sizes of calculation area of the ground massif at the design of the system are certain «support – ground massif », which provide sufficient exactness of calculation of parameters of the strain-stress state of support.

EXPRESS-ANALYSIS OF THE STRESS-STRAIN STATE OF THE UNFASTENED EXCAVATION ON THE BASIS OF MODEL WITH SINGLE PARAMETERS

Purpose. Bases of conducting of the express-analysis of the stress-strain state of the unfastened excavation of certain diameter on the basis of finite elements analysis of model with single parameters (closeness of soil and his module of resiliency) are developed in the article. Methodology. To achieve this goal, the authors, from the standpoint of the theory of elasticity and the fundamentals of the finite element method, carried out a justification for the development of the stress-strain state around the excavation of a circular outline. A finite element model for the excavation of a circular shape has been developed. The numerical analysis of the developed model is carried out. Findings. The parameters of the stress-strain state of a finite-element model for excavation of a circular outline with single parameters, as well as with specific values of the density of the soil and its elastic modulus, are obtained. A comparative analysis was carried out, which allowed to determine the dependencies between the two models. Originality. The regularities of the stressed and deformed states of a finite-element model with single parameters are established, formulas relating its SSS parameters to a model with specific parameters are proposed. (soil density, its modulus of elasticity). Practical value. The formulas for the transition from the SSS of a finite-element model with single parameters for specific cases of soil density and its modulus of elasticity are proposed for express analysis of the stress-strain state of the unfastened excavation.