scholarly journals Morphological features of the skeleton of a chinchilla and a rat in a comparative aspect

2021 ◽  
pp. 12-14
Author(s):  
I. V. Ziruk ◽  
M. E. Kopchekchi ◽  
A. V. Egunova ◽  
Ya. E. Yarosh

Exotic species of animals have recently become more and more popular and widespread; the approach to their diagnosis of diseases and treatment has its own nuances. Despite the similarity of species, there are differences that need to be taken into account. One of the fundamental problems of comparative anatomy is the disclosure of general patterns and specific features of the skeleton of animals. Despite the available detailed work in this direction, many questions concerning this problem still remain open and require further study.

2020 ◽  
Vol 45 (3) ◽  
pp. 668-680
Author(s):  
Danilo Marques ◽  
Rafael de Oliveira Franca ◽  
María Betiana Angulo ◽  
Gisela Mariel Via do Pico ◽  
Massimiliano Dematteis ◽  
...  

Abstract—Circumscription of genera in the tribe Vernonieae is complex due to overlapping morphological features among genera such as Chrysolaena, Echinocoryne, Lepidaploa, and Lessingianthus. These genera have been segregated from the genus Vernonia s. l., but their classification remains questionable because they lack clear diagnostic characters to contribute to this classification. Several studies have demonstrated the importance of the anatomy of cypselae for classification in Compositae; cypselae provide diagnostic characters for some genera. We studied the anatomy of the cypselae, including pericarp, callus, carpopodium, and pappus of Chrysolaena, Echinocoryne, Lepidaploa, and Lessingianthus, evaluating their potential for clarifying systematic problems in these genera. Our study demonstrated the cypselae features are uniform, and they do not contribute diagnostic characters useful in generic circumscription; however, cypselae anatomical characters do segregate some species. Our data also suggest that Chrysolaena, Echinocoryne, Lepidaploa, and Lessingianthus should be circumscribed in a single genus Lepidaploa.


Author(s):  
Necip Güven ◽  
Rodney W. Pease

Morphological features of montmorillonite aggregates in a large number of samples suggest that they may be formed by a dendritic crystal growth mechanism (i.e., tree-like growth by branching of a growth front).


Author(s):  
A. C. Reimschuessel ◽  
V. Kramer

Staining techniques can be used for either the identification of different polymers or for the differentiation of specific morphological domains within a given polymer. To reveal morphological features in nylon 6, we choose a technique based upon diffusion of the staining agent into accessible regions of the polymer.When a crystallizable polymer - such as nylon 6 - is cooled from the melt, lamellae form by chainfolding of the crystallizing long chain macromolecules. The regions between adjacent lamellae represent the less ordered amorphous domains into which stain can diffuse. In this process the lamellae will be “outlined” by the dense stain, giving rise to contrast comparable to that obtained by “negative” staining techniques.If the cooling of the polymer melt proceeds relatively slowly - as in molding operations - the lamellae are usually arranged in a radial manner. This morphology is referred to as spherulitic.


Author(s):  
C. S. Giggins ◽  
J. K. Tien ◽  
B. H. Kear ◽  
F. S. Pettit

The performance of most oxidation resistant alloys and coatings is markedly improved if the oxide scale strongly adheres to the substrate surface. Consequently, in order to develop alloys and coatings with improved oxidation resistance, it has become necessary to determine the conditions that lead to spallation of oxides from the surfaces of alloys. In what follows, the morphological features of nonadherent Al2O3, and the substrate surfaces from which the Al2O3 has spalled, are presented and related to oxide spallation.The Al2O3, scales were developed by oxidizing Fe-25Cr-4Al (w/o) and Ni-rich Ni3 (Al,Ta) alloys in air at 1200°C. These scales spalled from their substrates upon cooling as a result of thermally induced stresses. The scales and the alloy substrate surfaces were then examined by scanning and replication electron microscopy.The Al2O3, scales from the Fe-Cr-Al contained filamentary protrusions at the oxide-gas interface, Fig. 1(a). In addition, nodules of oxide have been developed such that cavities were formed between the oxide and the substrate, Fig. 1(a).


Author(s):  
M. S. Bischel ◽  
J. M. Schultz

Despite its rapidly growing use in commercial applications, the morphology of LLDPE and its blends has not been thoroughly studied by microscopy techniques. As part of a study to examine the morphology of a LLDPE narrow fraction and its blends with HDPE via SEM, TEM and AFM, an appropriate etchant is required. However, no satisfactory recipes could be found in the literature. Mirabella used n-heptane, a solvent for LLDPE, as an etchant to reveal certain morphological features in the SEM, including faint banding in spherulites. A 1992 paper by Bassett included a TEM micrograph of an axialite of LLDPE, etched in a potassium permanganate solution, but no details were given.Attempts to use n-heptane, at 60°C, as an etchant were unsuccessful: depending upon thickness, samples swelled and increased in diameter by 5-10% or more within 15 minutes. Attempts to use the standard 3.5% potassium permanganate solution for HDPE were also unsuccessful: the LLDPE was severely overetched. Weaker solutions were also too severe.


Author(s):  
Ming-Hui Yao ◽  
David J. Smith

The chemical properties of catalysts often depend on the size, shape and structure of the supported metal particles. To characterize these morphological features and relate them to catalysis is one of the main objectives for HREM study of catalysts. However, in plan view imaging, details of the shape and structure of ultra-fine supported particles (<2nm) are often obscured by the overlapping contrast from the support, and supported sub-nanometer particles are sometimes even invisible. Image simulations may help in the interpretation at HREM images of supported particles in particular to extract useful information about the size, shape and structure of the particles. It should also be a useful tool for evaluating the imaging conditions in terms of visibility of supported particles. P. L. Gai et al have studied contrast from metal particles supported on amorphous material using multislice simulations. In order to better understand the influence of a crystalline support on the visibility and apparent morphological features of supported fine particles, we have calculated images of Pt and Re particles supported on TiO2(rutile) in both plan view and profile view.


2003 ◽  
Vol 2 (1) ◽  
pp. 15-16
Author(s):  
A KOSTAREVA ◽  
G SJOBERG ◽  
K AMINEVA ◽  
A GUDKOVA ◽  
T SEJERSEN ◽  
...  

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