Cylindrical Axes Research Articles

Phylloclades of Jacksonia (Fabaceae)—leaf-like branches as adaptation to seasonally arid environments

Abstract Leaves of seed plants were evolutionarily derived through syngenesis (fusion) of the photosynthetic cylindrical axes of the earliest land plants and subsequent morphological diversification. However, in some later evolved taxa leaves became very reduced or entirely lost and photosynthesis was again restricted to stems. Reduction of photosynthetic area to stems is mostly found in plants from arid environments and is generally considered disadvantageous in competition for light with plants with leaves but may be useful if water is limiting. For taxa that cannot form normal leaves on adult plants, increasing photosynthetic area is only possible by modification of other plant parts. Some taxa produce leaf-like phylloclades that are developmentally different from leaves. We investigated Jacksonia floribunda and J. anthoclada (Fabaceae) leaves and phylloclades. In all Jacksonia species true leaves are only developed in the earliest ontogenetic stages, and subsequently are reduced to minor, nonphotosynthetic brownish scales. After several nodes on the seedling, photosynthetic phylloclades, each inserted in the axil of a scale, form the foliage. Immature phylloclades have vestigial nonphotosynthetic leaves borne on small projections from the edge of the blade. These soon abscise. The phylloclades are flattened branches and when mature have a distinctly reticulate venation and a sinuous margin with alternating mucronate tips where the vestigial leaves were attached. Jacksonia species demonstrate a transformational series where in most species foliage is reduced to branchlets. In a few others branchlets are winged forming cladodes or are condensed and laterally expanded to form phylloclades. Our findings on the more derived species in Jacksonia illustrate the complexity of plant morphological responses to evolutionary pressures of seasonal water limitation.

Curved mineral platelets in bone

Bone is a composite material principally made up of a mineral phase (apatite) and collagen fibrils. The mineral component of bone occurs in the form of polycrystalline platelets 2–6 nm in thickness. These platelets are packed and probably glued together in stacks of two or more, ranging up to >30 platelets. Here we show that most of these stacks are curved flat sheets whose cylindrical axes are oriented parallel to the long axes of collagen fibrils. Consequently, the curvature of the platelets is not detectable in TEM sections cut parallel to the collagen fibril axes. The radius of curvature around these axes ranges from about 25 nm (the average radius of the collagen fibrils) to 100′s of nm. The shapes of these curved forms contribute to the compressive strength of bone. Statement of significanceBone, the material of which bones are made, is mainly composed of a protein, collagen, and the mineral apatite (calcium phosphate). The crystals have long been known to be flat plates about 5 nanometers (nm) thick. Here we show that the crystals are bound together in curved platelets with a radius of curvature between 25 and several hundred nm, which weave between fibrils of collagen. Some platelets wrap tightly around fibrils. The platelets form stacks of from two to up to 30. The crystals in the platelets are all oriented parallel to the cylindrical fibrils even though most crystals are not in contact with collagen. These curved structures provide greater strength to bone.

Control of giant orbital angular momentum bursts of structured Laguerre-Gaussian beams in a medium with general astigmatism

We examined theoretically and experimentally the influence of astigmatic elements (for example, a cylindrical lens) on a structured Laguerre-Gaussian beam (sLG) when the lens axes are directed at an arbitrary angle to the laboratory coordinate axes (a general astigmatism). Although a structurally stable Laguerre-Gaussian (LG) beam contains a great number of axisymmetric modes (in the LG basis) with matching phases and amplitudes, their superposition already loses its original axial symmetry, but acquires new properties (for example, fast oscillations of the orbital angular momentum (OAM)), while the beam OAM cannot exceed the azimuthal number l of the original LG mode. The loss of axial symmetry occurs due to bringing phase and amplitude perturbations into each mode of the sLG beam, which destroy the ring dislocations. Since degenerate ring dislocations are formed by optical vortices with opposite topological charges, but with equal weights, their destruction is accompanied by appearing of vortex pairs in the form of topological dipoles (their number is equal to the radial number n). As a result, the mode spectrum of the sLG is extended to the value ±(2n + l). The astigmatic element (cylindrical lens) violates the equality of vortex weights in the dipoles, which leads to a sharp growing the OAM of the sLG beam. Moreover, the OAM can be controlled by changing the rotation of the cylindrical lens axes and the control parameters of the sLG beam. It is these processes that are discussed in detail in our article, both in theoretical and experimental aspects. We show that with a certain orientation of the cylindrical lens axes, the beam OAM can exceed the sum of the orbital and azimuthal numbers (OAM > n + l). Besides, we reveal that the intensity pattern of the astigmatic sLG beam can follow the rotation of the astigmatic element axes (the effect of the beam structure following the cylindrical lens axes) at certain relations between control parameters of the sLG beam and the astigmatic element.

Accuracy of a 3D printed sleeveless guide system used for fiber post removal: An in vitro study

ObjectivesThe removal of fiber post is often a challenging task. A 3D printed assembled sleeveless system that guides the head of the handpiece instead of the drill was developed to address this issue. This study aimed to evaluate the accuracy of this novel guide system using an in vitro approach. MethodsA standard maxillary typodont was digitized. The right first molar, the right central incisor, the left first premolar, and the left second molar in the digitized dentition were virtually crown-amputated. Four cylinders (diameter: 6 mm, height: 12 mm) were positioned along the directions of the main roots of these teeth to establish the virtual test model. Ten copies of the test model were printed using light-polymerizing resin. Four assembled sleeveless guide systems targeting the cylindrical axes were designed and printed using titanium alloy. One senior prosthodontist performed the drilling task targeting each cylindrical axis aided by the guide system or freehand (20 teeth each). The drilled models were scanned. The coordinates of the centers of all perforations and circular bases on the coronal and apical surfaces were obtained. The linear and angular deviations between the actual drilling path and the cylindrical axis for each tooth were calculated and analyzed. ResultsThe guided group exhibited significantly smaller linear and angular deviations than the freehand group (coronal linear deviation: 0.19 ± 0.09 mm vs. 0.35 ± 0.18 mm, p = 0.0012; apical linear deviation: 0.54 ± 0.19 mm vs. 1.71 ± 0.51 mm, p < 0.001; angular deviation: 2.67 ± 1.07° vs. 8.48 ± 2.86°, p < 0.001). ConclusionThe accuracy of the 3D printed assembled sleeveless guide system used for fiber post removal is superior to that of the freehand method within the limits of an in vitro design. Clinical significanceFor the removal of fiber posts, the present 3D printed sleeveless guide system can provide better accuracy that the conventional freehand method. This may justify the diffusion of the guided technique for fiber post removal.

Emergence of paraelectric, improper antiferroelectric, and proper ferroelectric nematic phases in a liquid crystal composed of polar molecules.

We have elaborated a theoretical approach for the description of polar nematic phases observed by Nishikawa etal. [Adv. Mater. 29, 1702354 (2017)0935-964810.1002/adma.201702354], their structures, and transitions between them. Specific symmetry contributions to the pair molecular potentials provide the molecular mechanisms responsible for the formation of proper and improper polarity on the macroscopic level. An improper antiferroelectric nematic M2 phase can arise between paraelectric nematic M1 and proper ferroelectric nematic MP in the temperature scale. The local polarization in M2 arises mostly due to the local splay deformation. The director distribution in M2 represents the conjugation of cylindrical waves with opposite splay and polarization signs. The director and polarization are parallel to the cylindrical domain axes in the middle of each cylinder but exhibit considerable (mostly radial) deformation on the periphery of each cylinder. Polarization vectors are mostly stacked antiparallel on the borders between the domains without the director disruption. The domain size decreases with the decreasing temperature, the percentage of the antiferroelectric decouplings increases, and M2 exhibits the first-order phase transition into proper ferroelectric MP. With the increasing temperature the domain size in the M2 phase increases, the domination of particular polar orientation of molecules reduces, and finally, the domain size diverges at particular temperature corresponding to the second-order phase transition from M2 to paraelectric M1. Variations of the polar and nonpolar orientational order parameters are estimated within each phase and between the phases. Our experimental and computer simulation results (also presented in the paper) fully support our theoretical findings.

COLLINEAR CONTROL OF OSCILLATION MODES OF SPATIAL DOUBLE PENDULUM WITH VARIABLE GAIN

This article is devoted to the study of controlled movements of spatial double pendulum with non-parallel cylindrical joints axes. The collinear control is used to swinging of the system by feedback. The most important property of collinear control is the ability of increasing system oscillations only on one oscillation mode. A modification of the collinear control law with variable gain depending on the energy level is investigated. It allows to control the system motions more flexible than in the case of constant gain. As a result, it is possible to observe a smooth transition from a linear oscillation mode to a nonlinear one with a gradual output to a steady oscillation motion with a given energy level. The obtained results are clearly illustrated by graph dependencies that demonstrate the swinging of the system on one oscillation mode from small to finite amplitudes.

Consistency of autorefraction by two autorefractors in 1138 Chinese children and adolescents

AIM: To assess the consistency of refractive errors measured by two autorefractors in myopia screening of school-age Chinese children. METHODS: Topcon RM-8900 and Tianle RM-9000 autorefractors were utilized to measure refractive errors under noncycloplegic condition in students aged 6 to 16y who were cluster sampled from four primary and secondary schools in Dongli district, Tianjin. Sperman correlation analysis and Bland-Altman method were used to evaluate the consistency of spherical diopters, cylindrical diopters and spherical equivalents measured by the two methods, and the axial difference distribution of astigmatism measured by the two methods was analyzed. RESULTS: A total of 2276 eyes of 1138 subjects with a mean age of 10.49±2.66y were finally enrolled. Spearman correlation analysis showed that sphere (r=0.958, P&lt;0.0001), cylinder (r=0.769, P&lt;0.0001), and spherical equivalent (r=0.962, P&lt;0.0001) measured by Tianle RM-9000 were highly correlated with those measured by Topcon RM-8900, respectively. Bland-Altman analysis showed spherical diopters measured by Tianle RM-9000 were significantly more hyperopic (P&lt;0.0001) with a mean difference of 0.44 D (SD: 0.37; 95%CI: -0.27, 1.16) while the maximum absolute value (1.13 D) of the difference within the 95%CI was above the clinically acceptable range; however, no significant difference (P=0.83) was found between cylindrical diopters measured by the two methods with a mean difference of -0.01 D (SD: 0.31; 95%CI= -0.62, 0.61) while the maximum absolute value (0.62 D) of the difference within the 95%CI was clinically acceptable. The proportion of the axial deviation within ±20° was 84.6% (1503/1777) in eyes with cylinder ≤ -0.25 D while that rose to 96.4% (853/885) in eyes with cylinder ≤ -0.75 D. CONCLUSION: Spherical diopters measured by Tianle RM-9000 have a significant hyperopia bias than those measured by Topcon RM-8900 while the consistency of cylindrical diopters and cylindrical axes is clinically acceptable.

Codium-like taxa from the Silurian of North America: morphology, taxonomy, paleoecology, and phylogenetic affinity

AbstractA 1901 report by the Smithsonian Custodian of Paleozoic Plants noted that the nonbiomineralized taxaButhotrephis divaricataWhite, 1901,B. newliniWhite, 1901, andB. lesquereuxiGrote and Pitt, 1876, from the upper Silurian of the Great Lakes area, shared key characteristics in common with the extant green macroalgaCodium. A detailed reexamination of theseCodium-like taxa and similar forms from the lower Silurian of Ontario, New York, and Michigan, including newly collected material ofThalassocystis striataTaggart and Parker, 1976, aided by scanning electron microscopy and stable carbon isotope analysis, provides new data in support of an algal affinity. Crucially, as withCodium, the originally cylindrical axes of all of these taxa consist of a complex internal array of tubes divided into distinct medullary and cortical regions, the medullary tubes being arranged in a manner similar to those of livingPseudocodium. In view of these findings, the three study taxa originally assigned toButhotrephis, together withChondrites verusRuedemann, 1925, are transferred to the new algal taxonInocladusnew genus, thereby establishingInocladus lesquereuxinew combination,Inocladus newlininew comb.,Inocladus divaricatanew comb., andInocladus verusnew comb. Morphological and paleoecological data point to a phylogenetic affinity forInocladusn. gen. andThalassocystiswithin theCodium-bearing green algal order Bryopsidales, but perhaps nested within an extinct lineage. Collectively, this material fits within a large-scale pattern of major macroalgal morphological diversification initiated in concert with the Great Ordovician Biodiversification Event and apparently driven by a marked escalation in grazing pressure.UUID:http://zoobank.org/97c5c737-b291-41a2-aceb-f398cac9537a

Development of a model of tool surface dressing when grinding with crossed wheel and cylindrical part axes

Three-dimensional geometric modeling of the forming process of cylindrical parts during grinding with crossed axes of it and the wheel has been carried out. Grinding of shafts, which are widely used in the automotive industry, machine tool industry, and rolls of strip rolling mills has been carried out at one location with a wide abrasive wheel oriented relative to the workpiece. Based on the obtained spatial model of shaping and removal of the allowance, the distribution of the allowance along the cutting area of the tool during grinding with an oriented tool has been studied. It has been shown that on the peripheral cutting section of the grinding wheel, roughing, finishing and calibration are combined.A modular three-dimensional model of dressing the grinding wheel peripheral section with a single-chip diamond tool during grinding with crossed axes of the tool and part using standardized modules of the dressing tool, orientation and shaping has been developed. Based on the presented model, the geometric accuracy of the tool peripheral section shaping after its dressing has been studied. Based on the presented model, the geometric accuracy of the tool peripheral section shaping after its dressing has been studied. In order to obtain the necessary microgeometry and cutting properties of abrasive wheels, in accordance with the features of processing the rolls of strip rolling mills with an oriented tool, dressing with a reduced feed rate of the dressing tool to the calibration section is proposed. The feed rate of the dressing single-chip tool depends on the value of allowance. Different feed rates of the dressing tool provide different development of the tool cutting peripheral section. This, in turn, increases the intervals between dressing processes of the grinding wheel, which operates in the blunt mode. Therefore, the resistance is increased, and the cost of processing is reduced. Implementation of the proposed method of wheel dressing during single-pass grinding with crossed axes of the tool and cylindrical part will provide high accuracy, quality of the machined surfaces, and also significantly increase the efficiency and productivity of processing. The developed dressing method can be applied for round grinding processes with crossed axes of the workpiece and abrasive wheels

Codiophyllum mexicanum sp. nov. (Halymeniaceae, Rhodophyta), first record of a stalked red alga associated with sponges in the western Atlantic

ABSTRACTThe species of the family Halymeniaceae are characterised by their multiaxial thallus and sexual reproduction, involving carpogonial branches and auxiliary cells borne in filamentous ampullae and tetrasporangia decussately or cruciately divided. Most species of the genera Thamnoclonium, Spongophloea, Codiophyllum and Carpopeltis belong to the group of red algae associated with sponges that, so far, have been recorded only in the Indian and Pacific Oceans. In a survey along the Campeche coast of Mexico, however, we found numerous specimens of a stalked red alga associated with a sponge. On the basis of molecular rbcL sequences and morphological features, these specimens proved to be a species of Codiophyllum. Given its independent phylogenetic position within the genus, morphological differences with C. flabelliforme and C. natalense (the other two known species), such as almost cylindrical, non-extended or flabellate axes, the lateral branching pattern, flattened specialised proliferations, and its geographic distribution, we described it as the new species C. mexicanum, the first stalked red alga associated with sponges described and recorded for the western Atlantic.

Rotational statistics in granular flows of smooth cylindrical particles

We report the results of an experiment to investigate the energy dissipation in the rotational degree of freedom for smooth cylindrical particles in a driven granular flow. The 2D geometry and the experimental design allow for the measurement of three degrees of freedom in the dynamics: the rotational degree of freedom for the disks to spin about their cylindrical axes as well as the two translational degrees of freedom of the particles within the cell. The rotational velocity statistics demonstrate non-Gaussian behavior as well as a significant amount of energy being dissipated through the flow via the tangential friction between particles. These results are significant in that many driven granular experiments use smooth cylindrical or spherical particles to investigate granular dynamics, but the contribution to the dynamics from the rotational degrees of freedom is often unmeasured.

Chromosome disentanglement driven via optimal compaction of loop-extruded brush structures

Eukaryote cell division features a chromosome compaction-decompaction cycle that is synchronized with their physical and topological segregation. It has been proposed that lengthwise compaction of chromatin into mitotic chromosomes via loop extrusion underlies the compaction-segregation/resolution process. We analyze this disentanglement scheme via considering the chromosome to be a succession of DNA/chromatin loops-a polymer "brush"-where active extrusion of loops controls the brush structure. Given type-II DNA topoisomerase (Topo II)-catalyzed topology fluctuations, we find that interchromosome entanglements are minimized for a certain "optimal" loop that scales with the chromosome size. The optimal loop organization is in accord with experimental data across species, suggesting an important structural role of genomic loops in maintaining a less entangled genome. Application of the model to the interphase genome indicates that active loop extrusion can maintain a level of chromosome compaction with suppressed entanglements; the transition to the metaphase state requires higher lengthwise compaction and drives complete topological segregation. Optimized genomic loops may provide a means for evolutionary propagation of gene-expression patterns while simultaneously maintaining a disentangled genome. We also find that compact metaphase chromosomes have a densely packed core along their cylindrical axes that explains their observed mechanical stiffness. Our model connects chromosome structural reorganization to topological resolution through the cell cycle and highlights a mechanism of directing Topo II-mediated strand passage via loop extrusion-driven lengthwise compaction.

Gödel spacetime: Planar geodesics and gyroscope precession

We study elliptic-like geodesic motion on hyperplanes orthogonal to the cylindrical symmetry axes of the Godel spacetime by using an eccentricity-semi-latus rectum parametrization which is familiar from the Newtonian description of a two-body system. We compute several quantities which summarize the main features of the motion, namely the coordinate time and proper time periods of the radial motion, the frequency of the azimuthal motion, the full variation of the azimuthal angle over a period, etc. Exact as well as approximate (i.e., Taylor-expanded in the limit of small eccentricity) analytic expressions of all these quantities are obtained. Finally, we consider their application to the gyroscope precession frequency along these orbits, generalizing the existing results for the circular case.

Meristotheca spinella Núñez-Resendiz, Dreckmann &amp; Sentíes, sp. nov. (Solieriaceae, Rhodophyta) a New Cylindrical Species from the Southwestern Gulf of Mexico

The genus Meristotheca J. Agardh is the second largest in Solieriaceae with 13 species widely distributed whose thalli are mainly flattened. On the basis of molecular and morpho-anatomical evidence, M. spinella Nunez-Resendiz, Dreckmann & Senties, sp. nov. is the second species in the genus with cylindrical axes to be described from the southwestern Gulf of Mexico. rbcL sequences and genetic distance values indicate its separation from other species within Meristotheca and from other morphologically similar species occurring in its known distribution range as M. cylindrica Nunez-Resendiz, Dreckmann & Senties. The numerous short branchlets that cover the margins of main axes and branches, among other relevant anatomical and reproductive characters, is the main difference from M. cylindrica, its sister species.

Electron beam additive manufacturing of Inconel 718 alloy rods: Impact of build direction on microstructure and high-temperature tensile properties

Inconel 718 alloy rods were fabricated by electron–beam melting (EBM), where the cylindrical axes (CAs) deviated from the build directions (BD) by 0°, 45°, 55°, and 90°. The microstructures and high-temperature tensile properties of the rods were investigated by taking into account the effect of the BD. Columnar grain structures or mixtures of columnar and equiaxed grains were obtained in the rods. The <1 0 0> direction of the grains tended to be oriented not only in the BD but also in the two horizontal EB scanning directions (SDs), which were perpendicular to each other. As a result, the crystal orientation of the rods could be controlled by appropriate choice of the CA. For instance, the rods oriented along the <1 0 0>, <1 1 0>, <1 1 1> directions could be fabricated by choosing their CAs parallel to the BD, face diagonal, and space diagonal of the cubic space defined by the BD and the two SDs, respectively. The highest strength was obtained for the <1 1 1> oriented rod. The dependence of strength on the rod orientation could be explained in terms of the anisotropies in the crystal orientation, columnar grain structure, and arrangement of the precipitate particles.

Cylindrical breeding blankets for fusion reactors

Blankets with a cylindrical structure have been developed for a water-cooled ceramic breeder concept considering a pipe break inside the blanket container. Most existing studies have examined a box structure for the blanket container. Structural change from a box to a cylinder can decrease in first wall thickness while maintaining the pressure resistance of the container. Two blankets with radial and toroidal/poloidal cylindrical axes have been developed. Their first walls are hemispherical and half cylindrical. The tritium breeding capabilities of the developed blankets were studied using Monte Carlo code MCNP5.14. Different combinations of breeder and neutron multiplier materials were considered. With the combination of lithium oxide and beryllium, the tritium breeding ratio of the blankets including surrounding gaps was evaluated as higher than 1.20, leading to a net tritium breeding ratio higher than 1.05.

Corrosion behaviour of CoCrMo alloy fabricated by electron beam melting

Electrochemical and static immersion tests in 1 mass% lactic acid solution are performed to investigate the corrosion behaviour of CoCrMo alloy fabricated by electron beam melting with cylindrical axes of samples deviating from build direction by 0°, 45° and 90°. All samples are dominantly composed of columnar γ-fcc phase with preferred crystal orientations. 90° sample, characterized by the largest grain size, lowest grain boundary density and fewest Cr-rich σ phase precipitates, demonstrates the highest corrosion resistance. The results suggest that amount of Cr-rich precipitates and grain boundary density both have much closer relation with corrosion resistance than crystal orientation.

Reduction of Support Structures and Building Time by Optimized Path Planning Algorithms in Multi-axis Additive Manufacturing

Additive manufacturing is an emerging technology that enables new product design. However, major inhibitors are long building times and a fixed build direction of the workpieces. In this article, new optimization and path planning methods for multi-axis additive manufacturing are presented going beyond conventional three-axis systems. This includes an adaptation of the building direction and an algorithm for the special case of cylindrical axes. These methods can reduce the production time drastically by avoiding support structures and by using the integration of predefined building blocks to substitute the infill. We present both, the new manufacturing process and the necessary computation methods for optimal process and path planning. Decreasing the building time and the amount of support structures paves the way for new application domains of additive manufacturing in the future.

Building direction dependence of corrosion resistance property of Ti–6Al–4V alloy fabricated by electron beam melting

Electrochemical measurements in 1 M HCl solution were performed to investigate the corrosion behaviour of Ti–6Al–4V alloy fabricated by electron beam melting (EBM) with cylindrical axes deviating from the building direction by 0°, 45°, 55°, and 90°. Microstructure characterization before and after the tests was carried out by using a variety of methods The results suggested that the corrosion resistance of EBM alloy in 1 M HCl solution increased slightly in the order of 45°, 90°, 55°, and 0°. Such difference can be ascribed to the grain boundary density and β phase constitution, which varied with the building direction.

Gracilaria corallicola and G. multipartita (Gracilariales, Rhodophyta), two related flattened European species

Two European species of Gracilaria possess flattened blades borne on cylindrical axes, namely, G. multipartita, known primarily from the Atlantic coast, and G. corallicola from the Mediterranean Sea. They are sister species that cluster with G. armata, G. bursa-pastoris and G. longa in rbcL analyses with strong bootstrap support. Blades of G. multipartita taper towards the tips, whereas those of G. corallicolla have broadly rounded tips. Spermatangia of G. corallicola are borne in shallow conceptacles (textorii-type) and data from the literature indicate that the same is true of G. multipartita. Cystocarp morphology is similar, with the gonimoblast filaments initially elongated, narrow and densely filled with cytoplasm, and with tubular nutritive cells issuing initially from lower gonimoblast cells and fusing with cells in the lowermost regions of the outer pericarp. Tetrasporangia are initiated terminally and displaced laterally with the production of side branches from the subterminal cell. The diagnostic characters of the Gracilariaceae are reviewed from a developmental perspective.