SEM study of structure and formation of the carbon cluster in the arc-discharge deposits

1993 ◽  
Vol 51 ◽  
pp. 756-757
Author(s):  
Dan Zhou ◽  
Supapan Seraphin ◽  
Jun Jiao
Keyword(s):  
Arc Discharge ◽  
Carbon Cluster ◽  
Structural Elements ◽  
Graphite Electrodes ◽  
Structured Surfaces ◽  
Sem Study ◽  
Carbon Arc ◽  
The Individual ◽  
Arc Discharges ◽  
Top View

The richly structured surfaces of the graphite electrodes in carbon arc discharges have been the subject of numerous studies in the past, due to the strong technological importance of the carbon arc lamp. However, since they were not known until recently , no attention was paid to the existence of carbon nanocluster which the discharge produces. Our previous results show that the variations of the production processing conditions will affect the properties of the individual carbon nanotube. We present here a scanning electron microscopy (SEM) study of the topography of the deposits at the graphite cathode, and attempt to correlate the growth behavior of nanotubes to the structural elements of the cathode surface.The starting material in this study is the carbonaceous deposit (i.e. slag) formed on the initial flat cathode as the anode is consumed during the arc discharge. The slag was carefully cleaved to make a SEM sample and the topography of the slag was characterized in both top view and cross-section.

scholarly journals Carbon Nanofoam by Pulsed Electric Arc Discharges

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
David Saucedo-Jimenez ◽  
Isaac Medina-Sanchez ◽  
Carlos Couder Castañeda
Keyword(s):  
Carbon Nanostructures ◽  
Arc Discharge ◽  
Low Cost ◽  
Molar Fraction ◽  
Electric Arc ◽  
Graphite Electrodes ◽  
Electric Arc Discharge ◽  
Pure Carbon ◽  
Arc Discharges ◽  
Dc Current

The aim of this article was to report the carbon nanofoam synthesis by a new method and a new catalytic mixture. Using the pulsed electric arc discharge method, carbon nanofoam was synthesized. The synthesis was carried out in a controlled atmosphere at 200 torr of hydrogen pressure. The pulsed electric arc discharge was established between two graphite electrodes with 22.8 kVA of power and 150 A DC current; the cathode was relatively motionless and was made of a pure carbon rod of 6 mm diameter, and the spinner anode was a pure carbon disc spinning at 600 rpm; over the disc was an annular cavity where the new catalytic mixture of 93.84/2.56/1.43/0.69/1.48 of C/Ni/Fe/Co/S molar fraction was deposited in a geometrically fixed way by 8 catalytic mixture blocks and 8 empty spaces, and the discharge frequency was 80 Hz. After the synthesis was made, the resulting products were deposited on the electrodes, proving that our method can synthesize different carbon nanostructures easily and at low cost.

CHARACTERISTICS OF A CARBON ARC DISCHARGE

2001 ◽  
Vol 5 (2) ◽  
pp. 10 ◽  
Author(s):  
K. Saidane ◽  
H. Lange ◽  
M. Razafinimanana ◽  
A. Huczko ◽  
C. Zedde ◽  
...  
Keyword(s):  
Arc Discharge ◽  
Carbon Arc

Molecular Dynamics Studies of Nanotube Growth in a Carbon ARC

1994 ◽  
Vol 359 ◽  
Author(s):  
C. J. Brabec ◽  
A. Maiti ◽  
C. Roland ◽  
J. Bernholc
Keyword(s):  
Molecular Dynamics ◽  
Electric Field ◽  
Electric Fields ◽  
Arc Discharge ◽  
Critical Diameter ◽  
Critical Factor ◽  
Carbon Arc ◽  
Dynamics Simulations ◽  
Nanotube Growth ◽  
Brenner Potential

ABSTRACTIt has been shown experimentally that the growth of carbon nanotubes in an arc discharge is open-ended. This is surprising, because dangling bonds at the end of open tubes make the closed tube geometry more favorable energetically. Recently, it has been proposed that the large electric fields present at the tip of tube is the critical factor that keeps the tube open. We have studied the effects of the electric field on the growth of the nanotubes via ab initio molecular dynamics simulations. Surprisingly, it is found that the electric field cannot play a significant role in keeping the tubes open, implying that some other mechanism must be important. Extensive studies of the energetics and simulations of the growth of tubes were performed using a threebody Tersoff-Brenner potential. Our results show that there exists a critical diameter of ∼ 3 nm above which a defect-free growth of a straight tubule is possible. Narrower tubes stabilize configurations with adjacent pentagons that lead to tube-closure and termination of the growth. This explains the absence of tube narrower than 2.2 nm in arc discharge experiments.

scholarly journals Electron Microscopy of the Tapetum Lucidum of the Cat

1959 ◽  
Vol 5 (1) ◽  
pp. 35-39 ◽  
Author(s):  
Maurice H. Bernstein ◽  
Daniel C. Pease
Keyword(s):  
Electron Microscopy ◽  
Basement Membrane ◽  
Capillary Network ◽  
Structural Elements ◽  
Connective Tissue Layer ◽  
Retinal Surface ◽  
Cell Layers ◽  
Retinal Epithelium ◽  
The Individual ◽  
Similar Density

The fine structure of the tapetum of the cat eye has been investigated by electron microscopy. The tapetum is made up of modified choroidal cells, seen as polygonal plates grouped around penetrating blood vessels which terminate in the anastomosing capillary network of the choriocapillaris. The tapetal cells are rectangular in cross-section, set in regular brick-like rows, and attain a depth of some thirty-five cell layers in the central region. This number is gradually reduced peripherally, and is replaced at the margin of the tapetum by normal choroidal tissue. The individual cells are packed with long slender rods 0.1 µ by 4 to 5 µ. The rods are packed in groups and with their long axes oriented roughly parallel to the plane of the retinal surface. Each cell contains several such groups. Cells at the periphery or in the outer layers of the tapetum are frequently seen to contain both tapetal rods and melanin granules, the latter typical of the choroidal melanocytes. Also melanocyte granules may have intermediate shapes. These observations plus the similar density of the two inclusions lead to the belief that the tapetal rods may be melanin derivatives. A fibrous connective tissue layer lies between the tapetum and the retina. The subretinal capillary network, the choriocapillaris, rests on this layer and is covered by the basement membrane of the retinal epithelium. The cytoplasm of the retinal epithelium exhibits marked absorptive modifications where it comes in contact with the vessels of the choriocapillaris. This fibrous layer and the basement membrane of the retinal epithelium apparently comprise the structural elements of Bruch's membrane.

scholarly journals Modeling of formation of carbon cluster groups in electric arc discharge plasma

2018 ◽  
Vol 80 (2) ◽  
pp. 108-113 ◽  
Author(s):  
A. N. Gavrilov
Keyword(s):  
Carbon Nanostructures ◽  
Arc Discharge ◽  
Experimental Studies ◽  
Particle Method ◽  
Cost Effective ◽  
Carbon Cluster ◽  
Collision Integral ◽  
Numerical Calculations ◽  
Plasma Synthesis ◽  
Interelectrode Space

The problem of modeling complex resource-intensive processes of plasma synthesis of carbon nanostructures (CNS) on the basis of mathematical and numerical methods of solution, focused on the use of parallel and distributed computing for processing large amounts of data, allowing to investigate the relationship and characteristics of processes to obtain an effective, cost-effective method of synthesis of CNS (fullerenes, nanotubes), is an actual theoretical and practical problem. This article deals with the problem of mathematical modeling of motion and interaction of charged particles in a multicomponent plasma based on the Boltzmann equation for the synthesis of ONS by thermal sublimation of graphite. The derivation of the collision integral is presented allowing to perform a numerical solution of the Boltzmann - Maxwell equations system with respect to the arc synthesis of CNS. The high order of particles and the number of their interactions involved simultaneously in the process of synthesis of CNS requires significant costs of machine resources and time to perform numerical calculations on the constructed model. Application of the large particle method makes it possible to reduce the amount of computing and hardware requirements without affecting the accuracy of numerical calculations. The use of parallel computing technology on the CPU and GPU with the use of Nvidia CUDA technology allows you to organize all the General-purpose calculations for the developed model based on the graphics processor of the personal computer graphics card, without the use of supercomputers or computing clusters. The results of experimental studies and numerical calculations confirming the adequacy of the developed model are presented. Obtained quantitative characteristics of the total pairwise interactions between the carbon particles and interactions with the formation of clusters of carbon with various types of ties in the plasma of the interelectrode space which are the basis of the synthesized nanostructures. The formation of carbon clusters occurs in the entire interelectrode space of the plasma with different intensity and depends on the process parameters.

scholarly journals On phenomena relating to the spectra of hydrogen and helium

1916 ◽  
Vol 93 (646) ◽  
pp. 27-28
Keyword(s):  
Accurate Determination ◽  
Principal Series ◽  
Black Body ◽  
Black Body Radiation ◽  
Balmer Series ◽  
Mean Values ◽  
Carbon Arc ◽  
The Mean ◽  
The Individual

In a previous paper the structure of broadened spectrum lines was investigated by a method involving the use of a neutral-tinted wedge as an accessory to the spectroscope. The present communication deals with a method for the accurate determination of the photographic intensities of spectrum lines and the reduction of such intensities to absolute values by comparison with the continuous black-body radiation of the carbon arc. These methods have been applied to a study of the relative intensity distribution in the spectra of helium and hydrogen under different conditions of excitation. It has been found that under certain specified conditions there is a transfer of energy from the longer to the shorter wave-lengths in any given series, and that, under such conditions, the associated series, and in particular the Diffuse series, are relatively enhanced at the expense of the Principal series. It has also been found that the distribution of intensity found in certain celestial spectra can be approximately reproduced in the laboratory. In any attempt to interpret the phenomena observed in connection with the Balmer series of hydrogen, it is necessary to know the particular type to which this series belongs. In order to decide this point a study has been made of the separations of the components of lines of the Balmer series of hydrogen, and the mean values of the separations of the doublets constituting the lines H a and H β have been found to be respectively 0.132 Å.U. and 0.033 Å.U. These values are consistent with the separations appropriate to a Principal series, and the first is in precise agreement with the value deduced by Buisson and Fabry. These results have been obtained by crossing a Lummer Gehrcke plate with the neutral wedge, and submitting the contours obtained to mathematical analysis, by means of which the distribution of intensity in the individual components, and the separation of the components, can be determined.

Pawilony bioniczne

BUILDER ◽  
2019 ◽  
Vol 258 (1) ◽  
pp. 26-28
Author(s):  
Anna Nowak ◽  
Wiesław Rokicki
Keyword(s):  
Fibonacci Sequence ◽  
Natural World ◽  
Digital Tools ◽  
Biological Processes ◽  
Structural Elements ◽  
Biological Models ◽  
Natural Processes ◽  
Advanced Knowledge ◽  
The Individual ◽  
Advanced Computer

INSPIRATIONS OF NATURE IN ARCHITECTURE. BIONIC PAVILIONS. The search for bionics is an interesting design notion, where the form of architectural objects is not only inspired by the aesthetics or patterns found in nature, but how its shape is reproduced by the natural processes of morphogenesis. Depending on how various patters in nature are replicated, a number of bionic modeling can be observed. The design based on the principles of forming natural structures requires some understanding of the ongoing processes and their changes. Thanks to the improvement of generative design methods allowing for the advanced knowledge in the field of technology to build the individual structural elements, a structural replication and analysis of biological processes is possible. The creation of mathematical models is an attempt to describe the forms found in the natural world, in particular the aspects of the morphogenesis. The Voronoi diagrams, or the Fibonacci sequence, which are increasingly used as a method of the discretization of the surface, deserve special consideration among the mentioned patterns found in nature. Digital tools play an important role in this process through the application of appropriate algorithms and advanced computer programs, but also experimental activities geared to building prototype solutions. The design of complicated spatial forms under different aspects is also aimed at searching for optimized technical and material solutions, in which unnecessary geometry is being eliminated. The transfer of biological models into architecture also applies to functional processes and systems found in nature in terms of shaping the coating elements. This paper is dedicated to the presentation of the completed experimental pavilions, which were created based on the bionic ideas, where the search for the multifunctional materials seems to be particularly important and could in turn revolutionize the building industry.

THEORETICAL FOUNDATIONS AND METHODOLOGICAL SCHEME FOR THE ASSESSMENT OF INDIVIDUAL EDUCATIONAL RESULTS OF STUDENTS IN THE PROCESS OF ADDITIONAL EDUCATION

2019 ◽  
Vol 10 (6/2) ◽  
pp. 75-80
Author(s):  
Svetlana S. IGNATOVICH ◽  
Vladlen K. IGNATOVICH
Keyword(s):  
Structural Elements ◽  
Adequate Understanding ◽  
Joint Solution ◽  
The Subject ◽  
Main Components ◽  
The Individual ◽  
Additional Education ◽  
Theoretical Foundations ◽  
Creative Tasks

The article is devoted to the problem of assessing the individual educational results of students in the process of additional education. This assessment in the concept of the authors is considered as the most important condition for the independent progress of the student along the individual educational trajectory. In this case, the student is the subject of its design. A model for assessing the individual educational results of students in the format of an educational event is proposed. The basic principle is formulated, which consists in fixing activity manifestations in a given situation, which testify to the student's ability to independently solve a creative task. These manifestations include: adequate understanding of the meaning of the problem being solved, competent determination of means and methods for solving it, competent access to various resources, and implementation of productive communications, ability to present and defend the solutions obtained. It is shown that the main components of such an educational event should be: joint solution of original creative tasks by students, expert-analytical support of this activity and free creative communication of different participants. A methodological scheme for the preparation and conduct of such an educational event is described. Its structural elements are: a preliminary analysis of data monitoring the development of students' creative activities; development and testing of a package of creative tasks; preparing a team of experts and equipping it with the necessary tools; development of the Festival program using a variety of creative communication formats of the participants; organization of information and analytical support of the Festival. Recommendations on the preparation of local working spaces for various types of activities of the Festival participants are given.

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