Tridimensional Shape Research Articles

Removal of dimethyl sulfide utilizing activated carbon fiber-supported photocatalyst in continuous-flow system

The present study investigated the adsorptional photocatalytic decomposition (APD) efficiency of activated carbon fiber-supported TiO 2 (ACF/TiO 2) in a continuous-flow reactor for the removal of dimethyl sulfide (DMS). The SEM analysis identified that the ACF/TiO 2 exhibited the same tridimensional shape as uncovered ACF and that a TiO 2 photocatalyst could be embedded in the surface of the ACF. In the absence of UV light, the time-series removal efficiencies by ACF and the ACF/TiO 2 units exhibited a similar pattern, which decreased gradually as it reached close to zero. However, the APD efficiency determined via the ACF/TiO 2 with UV light remained at nearly 60% during the remaining courses of the 13-h period, after decreasing from a maximum APD of 80%. The APD efficiencies depended upon the weights of the TiO 2 embedded into the ACFs, the UV sources, the relative humidity, and DMS input concentrations. During a long-term (219-h) APD test, the APD efficiencies dropped from 80% to ca 60% within 1 h after the initiation of the APD process and then fluctuated between 52% and 60%. No byproducts were measurable or observable in the effluent gas or on the ACF/TiO 2 surface. Consequently, the continuous-flow ACF/TiO 2 system could effectively be applied to control DMS without any significant functional deterioration.

Recuperação da topografia de ovos por meio da técnica de moiré e calibração independente

A recuperação da topografia de ovos por meio de análise de imagens digitais permite, de forma não destrutiva, a estimativa das massas da gema, da clara, da casca e totais, que são produtos amplamente utilizados na esfera industrial. O presente trabalho buscou desenvolver uma metodologia para a recuperação da forma tridimensional de ovos por meio de análise de imagens, em especial usando a técnica de moiré. Foram utilizados ovos de diferentes tamanhos, classificados em: XL (mais de 73 g), L (63 a 73 g), M (53 a 63 g) e S (até 53 g). Em cada teste realizado em laboratório, um ovo, aleatoriamente selecionado, foi iluminado com a projeção de grades, e as imagens foram capturadas e processadas para a obtenção da forma tridimensional do objeto pela técnica de moiré (TM). As dimensões dos seus eixos principais foram medidas por meio de um paquímetro, sendo usadas como referência para calibração da TM. Equações empíricas foram ajustadas para a correção das dimensões, apresentando coeficiente de determinação de 0,961; 0,955 e 0,988. A TM mostrou-se adequada para a recuperação da topografia de ovos, proporcionando erros menores ou iguais a 5,47%, com a clara necessidade de uma calibração independente, nas três dimensões, e sem a necessidade de usar um objeto calibrador.

Existence of a rotational axial component in the human humeral medullary canal

To explain surgical findings, we studied the anatomy of the human humeral medullary canal on a series of 28 bones in 16 patients and 9 dried bones. A methodology is described to find angle of medullary canal on CT scans regarding to an epicondylar reference axis. We found a constant tri-dimensional spiral shape of the medullary canal in the distal part of the bone. The relations between this first description and the literature are discussed.

Determination of the tridimensional shape of canopy gaps using two hemispherical photographs

The goal of this paper is to develop an approach to measuring tridimensional shape of canopy gap (TSCG), which is one of the most important factors affecting the understory light environment. TSCG may be expressed as a series of measurements: the gap size, the gap shape, and the canopy height in each azimuthal direction. The proposed method is based on two vertically separated hemispherical photographs of the canopy gap, and is thus named the two hemispherical photographs (THP) method. The small displacements between corresponding physical features on the two photographs can be used to measure the TSCG through a series of geometric equations based on the polar projection of the fisheye lens. In order to test the accuracy of this method, gap sizes were also measured by several ground-based methods, and the mean canopy height was measured by LaserAce hypsometer in a case study. The effects of two factors (the camera location and height difference between two photos) on the THP measures (the gap size, gap shape and mean canopy height) were also evaluated. Our results indicate that the THP measures of the gap size and mean canopy height have strong positive correlation and no significant difference with their corresponding alternatives. THP thus has a good accuracy. Moreover, ANOVA results show that all THP measures are not significantly affected not only by the height difference, but also by the location of the camera when the image is processed at 10° intervals in this sample. In addition, the THP measures of the gap size and gap shape are not influenced by the rugged canopy gap and the small-scale landform. In conclusion, THP is a rapid, simple, objective and accurate approach to the determination of TSCG.

Problèmes de construction de type polynomial II – Quelques résultats d'existence de plans sphériques isovariants exacts

Using computational commutative algebra, especially Gröbner bases, we first find out several polynomial designs and then state existence results in R 3 for spherical rotatable designs whose coordinates of their support points are known exactly, thus enabling us to derive the ideal of confounding polynomials thanks to tools defined in the framework of algebraic statistics. These designs can be of use in various settings such as response surface methodology or tridimensional shape analysis. To cite this article: F. Bertrand, C. R. Acad. Sci. Paris, Ser. I 346 (2008).

In vivo manganese-enhanced magnetic resonance imaging reveals connections and functional properties of the songbird vocal control system

Injection of manganese (Mn 2+), a paramagnetic tract tracing agent and calcium analogue, into the high vocal center of starlings labeled within a few hours the nucleus robustus archistriatalis and area X as observed by in vivo magnetic resonance imaging. Structures highlighted by Mn 2+ accumulation assumed the expected tri-dimensional shape of the nucleus robustus archistriatalis and area X as identified by classical histological or neurochemical methods. The volume of these nuclei could be accurately calculated by segmentation of the areas highlighted by Mn 2+. Besides confirming previously established volumetric sex differences, Mn 2+ uptake into these nuclei revealed new functional sex differences affecting Mn 2+ transport. A faster transport was observed in males than in females and different relative amounts of Mn 2+ were transported to nucleus robustus archistriatalis and area X in males as compared to females. This new in vivo approach, allowing repeated measures, opens new vistas to study the remarkable seasonal plasticity in size and activity of song-control nuclei and correlate neuronal activity with behavior. It also provides new insights on in vivo axonal transport and neuronal activity in song-control nuclei of oscines.

Structural shape optimization 3D finite-element models based on genetic algorithms and geometric modeling

The aim of this paper is to present and discuss the used of genetic algorithms and geometric modeling by means of β-splines surface representation in order to solve tri-dimensional shape optimization problems. Genetic algorithms have demonstrated to be a very robust search tool that models the evolution in artificial creatures. On the other hand, β-spline surface representation allows a very simple description on a high level of abstraction, and it is well suited to capture interactive influence. Other advantages are the validity of the shape description for large changes and the possibility of to generate optimal meshes. Finally, a numerical example is presented and discussed in order to show the great applicability of the developed tool.

A tridimensional study using cuts at a low temperature of the infratemporal region.

Although the infratemporal region is well defined anatomically, its complex topography has been the subject of numerous, and sometimes, opposite works. That is the reason why it appeared necessary for the authors to re-evaluate this topic using the original method of Combelles and Boyer, allowing to define three referential planes, and thereby, a tridimensional shape and the volume of this region. This study allows to conclude that the infratemporal region is a triangular prism with an horizontal main axis 47 mm long. Its anterior base has a mean area of 733 mm2. The posterior top consists of the Juvara slot and has a mean area of 490 mm2. This infratemporal prism contains another one, the pterygomandibular space, prismatic too. It widens out from coronoïd plane (93 mm2) to mandibular foramen plane (169 mm2) before ending as a narrow groove between the neck of the mandibular condyle and the interpterygoïd fascia. The volume of the pterygomandibular space is quite superior to the value usually reported in the dental literature. It is of 4.8 ml to 5.8 ml according to denture. These results point out the opportunity to accomodate more important volumes of anesthesic solutions, than the 1.8 ml usually performed, without any leak out of the infratemporal region.

Rat hepatocyte cultures and co-cultures in biotransformation studies of xenobiotics

Long-term cultures of hepatocytes could represent a suitable in vitro model for botransformation studies of xenobiotics. At present however, no ideal culture system can be proposed since, in all existing models, phenotypic changes occur, affecting selectively some components of phase I and/or phase II xenobiotic metabolism. From the authors' own results and recent studies of several other investigators, carried out on rat hepatocytes, it becomes clear that four groups of factors may affect biotransformation capacity: soluble medium factors, extracellular matrix components, cell-cell interactions and factors affecting replication. For the maintenance of liver-specific functions, it seems of utmost importance that the tridimensional shape of the hepatocytes is kept. Usually, phase II enzymatic activity is better kept than that of phase I. The cytochrone P450 dependent monoxygenases, in particular, are easily lost. Interesting is the observation that co-cultures of rat hepatocytes with rat liver epithelial cells exhibit higher and much better preserved phase I and phase II biotransformation than monocultures. Clearly, further research is needed to improve this promising in vitro model.

Searching for geometric molecular shape complementarity using bidimensional surface profiles

The study presented herein is a bidimensional approach to the complementarity of two molecular surfaces. From two chosen sections we have established a methodology of generating the optimal matching of two shapes. Our approach consists in describing two molecular surface sections by a shape vector (the angular profile), in finding their matching patterns by comparison of the two profiles, and in optimizing the relative locations of the two sections in two-dimensional space, using rotations and translations defined by geometric characteristics. The set of optimal configurations are successively displayed on a screen. Satisfying results have been obtained for the matching of the complex kallikreine Atrypsin pancreatic bovin 2. This efficient method could be used as a preprocessing for a tridimensional shape complementarity approach between two molecular surfaces.

ABO-blood-group-related idiotypic network: Mimicry of oligosaccharide epitope by rabbit antiidiotypic antibodies to murine monoclonal anti-A antibody

The idiotypy of antibodies (Ab) specific for oligosaccharide determinants of blood groups of the human ABO system was studied through a cascade. Xenogenic antiidiotypic Ab (Ab2) raised in rabbits to the murine monoclonal anti-A61 (Ab1) were screened for reactivity with various anti-ABH Ab. Three anti-A and three anti-A,B monoclonal antibodies (mAb) which were developed in the same mouse strain as that producing Ab1, as well as a human polyclonal anti-A, were found to share cross-reactive idiotopes (CRI) with Ab1. CRI on murine mAb could be due to a Biozzi recurrent Id on anti-A Ab reacting with anti-Id “à la Oudin”, while CRI on human anti-A Ab suggested the presence of paratope-induced anti-Id. Inhibition by Ab2 of haemagglutination of A, B or O human red blood cells by many murine anti-ABH mAb, and by polyclonal or monoclonal human anti-A, strongly supported the occurence of anti-Id mimicking ABH epitopes belonging to type 2 determinants carried by human erythrocytes. Furthermore, a rabbit immunized with Ab2 produced a potent Ab3 response characterized by anti-H-type-2 specificity. Altogether, these results are consistent with the first successful production of anti-Id Ab that mimics the tridimensional shape of a well defined and strictly carbohydrate epitope, eliciting a haemagglutinating Ab3.

Shape constancy and polar perspective.

The distortion of polar perspective depends on the depth of the tridimensional shape and on the observation distance. In four experiments using 54 undergraduates as subjects, we found that a compensation process which takes depth and observation distance into account corrects for such distortions. Compensation was demonstrated in experiments in which deceptive information on depth and on observation distance was provided. The result was distortions of the perceived shapes that would be expected if compensation were based on the deceptive information.

Some structural aspects of precapillary vessels.

According to the present state of the art, the former Chambers-Zweifach conception is no longer tenable as the ubiquitous module of microvascular organization. Any attempt to define the consecutive segments of precapillary vessels in a random collection of sectioned tissues is impaired by the extreme scatter of variations and the lack of additional criteria necessary for a distinct classification. With these inadequacies in mind, arterioles, terminal arterioles, and their precapillary segments (sphincters?) are identified by applying the following parameters: luminal diameter, composition of the subendothelial space, and thickness as well as completeness of the media. Endothelial components of particular functional significance are different types of cytoplasmic filaments and myoendothelial junctions. The former serve as a cytoskeleton and may provide a mechanism to adapt endothelial tensile strength to variations of shearing forces. The latter appear to be sites of firm intercellular attachment and of electrotonic coupling of the endothelium to the underlying smooth-muscle cells. The former unanimously accepted helicoidal arrangement of vascular smooth muscle (VSM) must be modified according to most recent findings, and the tridimensional shape of VSM and its transition to pericyte-like elements remain to be further elucidated. Future effects, from which solutions to the many open problems may be expected, must therefore aim at combined vital-, light-, and electron-microscopic studies of the methodically accessible microvascular beds. This necessity has already been recognized, and first promising steps have been taken.

Purkinje Cell Ontogeny: Formation and Maintenance of Spines

This chapter discusses the morphological analysis of microenvironmental factors influencing the molding of the Purkinje cell dendritic tree. Emphasis is given on the problem of the formation and maintenance of dendritic spines, because they are, by far, the most numerous receptor sites in these neurons. During normal development, Purkinje cell differentiation occurs in a concomitant manner with the development of its synaptic inputs. Climbing fibers reach Purkinje cells, establishing early axo-somatic synapses that are already functional postnatally by day three. This pericellular climbing plexus originates from 3–4 different climbing fibers. The further development of the Purkinje cell dendritic tree parallels the growth of climbing fibers and the maturation of their synapses. By day 12–15, the climbing fiber varicosities make synapses on thorns emerging from the thick Purkinje cell dendritic branches. At this stage, the immature multiple innervation is transformed into the definitive one-to-one relationship, which characterizes the climbing fiber-Purkinje cell synapses in adult animals. During the 2nd and 3rd postnatal weeks, migration of the bulk of granule cells takes place, giving rise to the millions of parallel fibers found in the molecular layer. The development of parallel fibers is accompanied by the formation of thin terminal branches of the Purkinje cell dendritic arborization—the spiny brundzlets—and by the achievement of the espalier arrangement of these dendritic trees that give the Purkinje cells their unique tridimensional shape.

A New Method of Expressing Particle Sphericity

ABSTRACT For a more complete characterization of the shape of sedimentary particles, a method for tridimensional shape analysis is described. It is proposed to return to Wadell's original definition of sphericity, i.e., the degree of true sphericity, as the basis for the quantitative description of shape. However, instead of analyzing each grain form as such, the shape is approximated by a tetrakaidekahedron which is defined by three mutually perpendicular particle dimensions. Using these measured dimensions and the geometric characteristics of the tetrakaidekahedron, the shape of particles can be defined simultaneously in terms of Wadell's and Zingg's shape factor. An expression is derived for approximating the degree of true of sedimentary particles. It is shown that th use of this expression as the working sphericity seems to be justified and may be considered an improvement over other approximations. An example of the workability of the technique is given by the tridimensional shape analysis of the component grains of a sample of Woodbine sandstone. It is thought that the method described can be of use in many phases of stratigraphic and sedimentary research.