Large Ellipsoids Research Articles

Study on the Bronze Weapons Excavated from Xichuan, China

The collection of twelve bronze artifacts discovered in Xichuan provides invaluable historical insights into the Warring States period (476 BC to 221 BC) of ancient China. To investigate their fabrication techniques and current state of preservation, a comprehensive analysis was conducted using a metallographic microscope, a scanning electron microscope, and an electron spectrometer to examine the microstructure and elemental composition of the artifacts. The findings revealed that the copper content in these bronze artifacts varied between 41.82% and 87.95%, the tin content ranged from 6.79% to 46.88%, and the lead content was less than 28.96%. The microstructure exhibited an α-solid-solution dendritic-crystal-segregation structure, with a substantial amount of (α + δ) eutectic distributed in an island-like pattern. Lead was dispersed unevenly, appearing as small granules and large ellipsoids. The composition of these weapons aligned with their intended use, adhering to the manufacturing standards of traditional Chinese bronzes. However, their state of preservation was suboptimal, necessitating immediate protective measures. This study contributes physical evidence to the research on early Chinese bronze production and offers scientific guidance for the conservation and restoration of these bronze artifacts.

New insights into the retinal microstructure-diurnal activity relationship in the African five-lined skink (Trachylepis quinquetaeniata) (Lichtenstein, 1823)

BackgroundThe retinae of diurnal vertebrates have characteristics. Most lizards are strictly diurnal, and their retinal morphology is still unknown.Materials and methodsThe retina of the African five-lined skink (Trachylepis quinquetaeniata) was studied using light and transmission electron microscopy.ResultsThe retina's ten layers were all detected. The inner nuclear layer was the thickest by an average of 67.66 μm, and the inner plexiform layer was 57.564 μm. There were elliptical, long cylindrical, and spherical melanosomes (small and large) in the pigment epithelial layer of the retina. The cylindrical melanosomes had a large area on the lateral surfaces of cones to increase light scatter absorption. The photoreceptor layer of the retina had cones only. There were single and double cones, with the double cones consisting of principal and accessory cones. The cones had inner and outer segments separated by oil droplets. A spherical paraboloid body existed between the limiting membrane and the ellipsoid. All single cones had a paraboloid, and double cones had a large paraboloid in the accessory cone. The presence of paraboloids and large ellipsoids with mitochondria of varying sizes may have helped focus the light on cone segments.ConclusionThe African five-lined skink's eye was light-adapted due to a variety of retinal specializations related to the demands of its diurnal lifestyle in its environment.

Radial segregation of binary-sized ellipsoids in a rotating drum

Rotating drums are widely used in industry for powder mixing, milling, coating and drying processes. Segregation is inevitable when using a rotating drum to mix granules differing in size, density or shape. Size segregation in rotating drums has received comprehensive studies over the past decades, but most of the studies concentrate on spherical particles. Particle shape, as one of the important particle properties, could affect size-induced segregation significantly. However, such an effect is still poorly understood. In this work, DEM is employed to study the radial segregation of binary-sized ellipsoidal particles in a rotating drum. The segregation patterns for both spheres and ellipsoids are presented and compared. The effects of aspect ratio, size ratio and rotating speed on the extent of segregation are investigated. Generally, large particles tend to segregate to the periphery of the bed, whereas small ones are accumulated in the core section. As particle aspect ratio deviates from unity, i.e. elongated or platy shape-type, the extent of segregation is reduced. Small ellipsoidal particles tend to be entrained by large ellipsoids causing less segregation. The decrease of size ratio of small to large particles does not necessarily lead to a higher segregation extent. The results also show that in rolling or cascading regimes, increasing the rotating speed can reduce the extent of segregation for both spheres and ellipsoids. The studies also indicate that the initial states of mixtures do not affect the final segregation patterns.

Diffusion of ellipsoids in laboratory two-dimensional turbulent flow

We report on the transport properties and orientational dynamics of ellipsoidal objects advected by laboratory two-dimensional turbulence. It is found that ellipsoids of different sizes have preferential direction of transport, either along their major axes or minor axes. The two components of the ellipsoid diffusion coefficient depend on the ratio of the length of the ellipsoids along major axes aa to the turbulence forcing scale Lf. Large ellipsoids (aa > Lf) diffuse faster in the direction parallel to their major axes. In contrast, small ellipsoids diffuse faster in the direction transverse to their major axes. We study this transition vs the ratio aa/Lf and relate it to the coupling between translational and rotational motion of anisotropic objects. The features of the turbulent transport of ellipsoids can be understood by considering the interaction of these anisotropic objects with the underlying structure of two dimensional turbulent flows made of meandering coherent bundles.

Shape-dependent internalization kinetics of nanoparticles by membranes.

Internalization of nanoparticles by biomembranes is critical for nanomedicine development; however, this process, especially its dynamics aspect, is still not well understood. Using coarse-grained molecular modeling combined with free energy calculations, we studied the endocytic process for spherical, prolate and oblate particles with varied aspect ratios, volumes and interaction strengths. Rich dynamic wrapping behaviors have been observed. Small ellipsoids follow a pathway that includes particle laying-down, membrane invagination and wrapping, and then disruption of the membrane neck. However, the step of particle laying-down is skipped for large ellipsoids. Because of the significantly decreased local mean curvature at the side edge (oblate ellipsoid) or tips (prolate ellipsoid), the rotation is less favorable for particles with larger volume. Given the existence of a local minimum and an energy barrier during the endocytic process presented by our free energy calculations, the oblate particle provides longer endocytic time than the corresponding prolate particle. For large particles, the free energy surfaces are smooth, with no local minimum. When we increase the interaction strength between the membrane and the particle, the endocytic process is greatly affected. Moreover, a "sandwiched structure", in which the particle lays between the two membrane layers, was observed for both prolate and oblate particles.

Computational study of radiation torque on arbitrary shaped particles with MLFMA.

The surface integral equation (SIE) method is used for the computational study of radiation torque on arbitrarily shaped homogeneous particles. The Multilevel Fast Multipole Algorithm (MLFMA) is employed to reduce memory requirements and improve the capability of SIE. The resultant matrix equations are solved iteratively to obtain equivalent electric and magnetic currents. Then, radiation torque is computed using the vector flux of the pseudotensor over a spherical surface tightly enclosing the particle. We use, therefore, the analytical electromagnetic field expression for incident waves in the near region, instead of the far-field approximation. This avoids the error which may be caused when describing the incident beam. The numerical results of three kinds of non-spherical particles are presented to illustrate the validity and capability of the developed method. It is shown that our method can be applied to predict, in the rigorous sense, the torque from a beam of any shape on a particle of complex configuration with a size parameter as large as 650. The radiation torques on large ellipsoids are exemplified to show the performance of the method and to study the influence that different aspect ratios have on the results. Then, the code is used for the calculation of radiation torque on objects of complex shape including a biconcave cell-like particle and a motor with a non-smooth surface.

Plastic deformations in kyanites by tectonometamorphic processes: a single-crystal X-ray diffraction study

AbstractThe crystalch emistry and crystal structure of naturalky anite crystals from the Eclogitic Micaschists Complex of the Sesia-Lanzo Zone, Western Italian Alps, have been investigated by means of optical microscopy, wavelength dispersive X-ray microanalysis, and single-crystal X-ray diffraction. The association of kyanite + garnet + phengitic-mica + chloritoid suggests that the eclogite-facies stages occurred at P ≤ 2.1 GPa and T ≤ 650ºC. Kyanite grains are large (cm-sized) porphyroblasts grown dynamically during one of the deformational events related to the subduction of the Austroalpine continentalcr ust. Under the polarizing microscope, kyanite grains show almost homogeneous cores, whereas rims are sometimes symplectitic aggregates of quartz and kyanite, confirming at least two stages of growth most likely related to the multistage deformational history of these rocks. Chemical analysis shows that Fe3+ is the major substituting cation for Al3+, ranging between 0.038 and 0.067 a.p.f.u.The single-crystal X-ray diffraction investigation of the kyanites shows severely textured patterns on the (h0l)*-plane. Such evidence is not observed in the unwarped diffraction patterns on (0kl)* and (hk0)*. The most significant difference between the structuralp arameters refined in this study, with respect to those of previously published unstrained gem-quality crystals, concerns the displacement parameters. The anisotropic displacement ellipsoids of all the atomic sites are significantly larger than those previously described, and systematically oriented with the largest elliptical section almost perpendicular to [010]. The larger ellipsoids in the kyanite crystal investigated here reflect the displacement of the centre of gravity of the electron distribution, rather than an anomalous atomic thermal motion. The magnitude and orientation of the displacement parameters and the textured/strained diffraction pattern may be the result of two combined effects: (1) that the kyanite crystals are actually composed of several blocks; (2) the crystals are affected by a pervasive residual strain, as a result of tectonometamorphic plastic deformations and re-crystallization.

Sharp asymptotics of the metric entropy for ellipsoids

The sharp asymptotics for the (metric) entropy numbers of large ellipsoids in a Hilbert space is derived. The condition imposed is slow variation of the lengths of the semi-axes.

Synthesis and Crystal Structure of Tetraphenylarsonium Pentachlorocarbonylosmate(IV), (Ph4As)[OsCl5(CO)

The structure of tetraphenylarsonium pentachlorocarbonylosmate(IV), (Ph4As)[OsCl5(CO)], the first example of a halogenocarbonyl complex with osmium in the oxidation state +IV, has been determined at 208 K by single crystal X-ray diffraction: tetragonal, space group P4/n with a = 12.821 , c = 8.084 Å, Z = 2. There are short intermolecular contacts between neighbouring anions along the tetragonal axis c and unusually large displacement ellipsoids of the carbonyl group and the four equatorial Cl ligands arising from a positional disorder of the complex anion. By analogy with a variety of reported structures of the (Ph4As)[RuNCl4] structure type this is attributed to the close packing of the cation sublattice. Compared to other monocarbonylosmates the Os-C bond of 1.94(2) Å is extraordinaryly long while the bond between Os and the trans coordinated Cl ligand of 2.286(3) Å is rather short.

Representing bounded fault classes using neural networks with ellipsoidal activation functions

Feedforward neural networks are characterized by the choice of the squashing function, the activation function and the error criterion function. The standard feedforward network considers a sigmoid squashing function, linear activation function and RMS error minimization as the error criterion. These networks exhibit generalization problems because the linear discriminant function creates half spaces of high activation. For fault diagnosis, we are specifically interested in classifiers that generate bounded regions. To address this and related issues, we propose two ideas in this paper: (i) the use of an ellipsoidal activation function; and (ii) an algorithm for generating hidden nodes and hence the network structure adaptively. Ellipsoidal activation leads to the generation of bounded ellipsoidal regions in the space of the network inputs and is thus suitable for fault classification. The standard backpropagation algorithm does not guarantee the proper determination of the ellipsoidal activation functions as it may run into local minima problems, attributable mainly to poor choices of initial network weights. The notion of a bounding ellisoid is introduced to determine proper initial weights and also avoid unnecessarily large ellipsoids. A new algorithm for determining the number of hidden nodes adaptively is also proposed. New hidden nodes are added in regions of input space where the representation is not adequate and nodes are stripped away when they do not contribute to proper classification. This removes the arbitrary nature of assigning hidden nodes to the network as practiced in the standard approaches. The success of the proposed framework is demonstrated on a variety of examples including adjacent distributions with nonlinear boundaries. The diagnosis of a reactor—distillation column system is presented to show the suitability of the ellipsoidal representation by analyzing the structure of the fault space. The advantages of ellipsoidal units over radially symmetric units is discussed in this context.

Expression of Human Cytomegalovirus Immediate Early Antigens Is Responsible for a Novel Chromatin Structure of Infected Human Embryonic Lung Cells

Whereas human embryonic lung (HEL) cells displayed chromatin fibers composed of a repeat of conventional nucleosomes of 15 nm in diameter, human cytomegalovirus (HCMV) infection induced transient appearance of a novel chromatin structure composed of a repeat of large ellipsoids of 45-65 nm X 15-30 nm with linkers of 50-60 nm long and 6-7 nm thick. Essentially the same change in chromatin structure could be induced when uninfected HEL cell nuclei were incubated in vitro with a 0.4 M NaCl nuclear extract from HCMV-infected HEL cells expressing immediate early antigens (IEA's) or with a similar nuclear extract from NIH/3T3 cells constitutively expressing HCMV IEA's. The latter cell line was established by transformation of the mouse cells with a plasmid carrying the HCMV major immediate early and immediate early 2 genes. These results together with those of control experiments suggest that the expression of IEA's is directly or indirectly responsible for the appearance of the novel chromatin structure in HCMV-infected HEL cells.

Elementary Results for Scattering by Large Ellipsoids

Elementary high-frequency approximations for scattering by an arbitrary body are specialized to ellipsoids and applied in detail for source and observation points at distances large compared to the scatterer's size. It is shown, for example, that, if the direction of observation is varied in a fixed plane containing the direction of incidence, then except for the near-forward direction (“shadow region”) the first approximation for the far-distant field for a given ellipsoid is specified by a “universal curve.” In particular, if the fixed plane contains an axis of the ellipsoid, then there is a unique curve for the intensity versus the angle measured from the reflection of the direction of incidence in the contained axis. For the special case of the spheroid, the field on the “axially specular” cone (the cone defined by the angle of incidence with the axis of rotation) remains constant until one gets near the shadow region, and the fields on adjacent cones (i.e., with generators at other than the specular angle with the axis) vary slowly with the azimuthal angle; for many practical purposes, we may neglect the slowly varying effects and approximate the reflected intensity pattern in the vicinity of the axially specular cone by a conical lobe of revolution. Numerical examples are given for a family of spheroids; e.g., we determine contours of constant intensity on a plane containing the source as functions of the spheroid's distance from the plane, etc.