An approximation solution for the problem of internal diffusion in a biporous sorbent with Langmuir isotherm. 1. The initial stage of the diffusion process in laminar or cylindrical grains with impermeable side surfaces

1979 ◽  
Vol 28 (8) ◽  
pp. 1565-1568
Author(s):  
P. P. Zolotarev ◽  
V. I. Ulin
Keyword(s):  
Diffusion Process ◽  
Langmuir Isotherm ◽  
Internal Diffusion ◽  
Approximation Solution ◽  
Initial Stage ◽  
Biporous Sorbent

scholarly journals Problems of seasonality of sugar production from beets

2020 ◽  
Vol 82 (1) ◽  
pp. 64-69 ◽  
Author(s):  
V. A. Golybin ◽  
V. A. Fedoruk ◽  
N. A. Matvienko
Keyword(s):  
Diffusion Process ◽  
Raw Materials ◽  
Sugar Content ◽  
Extraction Process ◽  
Feed Water ◽  
Negative Consequences ◽  
Root Crops ◽  
Initial Stage ◽  
Beet Pulp ◽  
Physical And Chemical

In recent years, the annual processing of sugar beet in Russia is 45 million tons or more, which allows to produce white sugar in the amount of 6.0 million tons or more. during the production season, the quality of beets does not remain constant – not only its sugar content changes, but also the content of harmful soluble non-sugars, as well as physical and chemical parameters - the mass of root crops decreases due to wilting, reducing turgor, respiration and germination, rotten mass appears as a result of microbiological and enzymatic processes and the formation of foci of mucous bacteriosis. One of the main tasks of improving the diffusion process is to increase the elasticity of beet tissue and reduce the intensity of the transition of pectin substances into the diffusion juice. This goal is achieved by using effective chemical reagents in the composition of the feed water introduced into the diffusion apparatus, as well as processing of beet chips immediately before the sucrose extraction process; reducing the temperature of desugarisation of beet pulp in the diffusion apparatus in the allowable interval. The method of intensification of sucrose extraction using the method of treatment of feed water in an electric field is proposed. Improvement of the dispersed composition of the resulting sediment particles is facilitated by the return to the preliming of the carbonate suspension of juice II saturation, carried out using an activated suspension of filter perlite. The homogeneity of calcium carbonate particles and correspondingly high filtration rates of saturation juice are formed due to the active circuit of the internal circulation of the juice. The use of the proposed recommendations during the implementation of technological processes in their implementation in modern equipment of the diffusion process and purification of the obtained juice allow to minimize the negative consequences of beet processing both at the initial stage of the production season when technically not ripe root crops are received, and during the end of the season when processing raw materials of reduced quality.

scholarly journals Study on Initial Stage of Diffusion Process of Turbidity in Direct Dumping of Soil.

1995 ◽  
pp. 77-86 ◽  
Author(s):  
Masahiro Tamai ◽  
Kohji Muraoka ◽  
Akira Murota ◽  
Hiroki Machida
Keyword(s):  
Diffusion Process ◽  
Initial Stage

Internal diffusion in a biporous sorbent in the case of a rectangular sorption isotherm

1979 ◽  
Vol 36 (3) ◽  
pp. 353-357
Author(s):  
P. P. Zolotarev ◽  
V. M. Starov ◽  
I. A. Yabko
Keyword(s):  
Sorption Isotherm ◽  
Internal Diffusion ◽  
Biporous Sorbent

Reaction couples of ceramic thin films prepared by CVD

1988 ◽  
Vol 46 ◽  
pp. 798-799
Author(s):  
D.W. Susnitzky ◽  
S.R. Summerfelt ◽  
C.B. Carter
Keyword(s):  
Thin Film ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Solid State Reactions ◽  
Spatial Distributions ◽  
Diffusion Couples ◽  
Kinetics Studies ◽  
Ceramic Thin Films ◽  
Initial Stage

Solid-state reactions have traditionally been studied in the form of diffusion couples. This ‘bulk’ approach has been modified, for the specific case of the reaction between NiO and Al2O3, by growing NiAl2O4 (spinel) from electron-transparent Al2O3 TEM foils which had been exposed to NiO vapor at 1415°C. This latter ‘thin-film’ approach has been used to characterize the initial stage of spinel formation and to produce clean phase boundaries since further TEM preparation is not required after the reaction is completed. The present study demonstrates that chemical-vapor deposition (CVD) can be used to deposit NiO particles, with controlled size and spatial distributions, onto Al2O3 TEM specimens. Chemical reactions do not occur during the deposition process, since CVD is a relatively low-temperature technique, and thus the NiO-Al2O3 interface can be characterized. Moreover, a series of annealing treatments can be performed on the same sample which allows both Ni0-NiAl2O4 and NiAl2O4-Al2O3 interfaces to be characterized and which therefore makes this technique amenable to kinetics studies of thin-film reactions.

Decoration technique and surface physics

1978 ◽  
Vol 36 (1) ◽  
pp. 436-437 ◽  
Author(s):  
H. Bethge
Keyword(s):  
Diffusion Path ◽  
Special Importance ◽  
Surface Physics ◽  
Step Structure ◽  
Initial Stage ◽  
Special Cases ◽  
Atomic Surface ◽  
The Mean ◽  
Bulk Structure ◽  
Decoration Technique

Besides the atomic surface structure, diverging in special cases with respect to the bulk structure, the real structure of a surface Is determined by the step structure. Using the decoration technique /1/ it is possible to image step structures having step heights down to a single lattice plane distance electron-microscopically. For a number of problems the knowledge of the monatomic step structures is important, because numerous problems of surface physics are directly connected with processes taking place at these steps, e.g. crystal growth or evaporation, sorption and nucleatlon as initial stage of overgrowth of thin films.To demonstrate the decoration technique by means of evaporation of heavy metals Fig. 1 from our former investigations shows the monatomic step structure of an evaporated NaCI crystal. of special Importance Is the detection of the movement of steps during the growth or evaporation of a crystal. From the velocity of a step fundamental quantities for the molecular processes can be determined, e.g. the mean free diffusion path of molecules.

Nucleation and initial growth of Pd2Si crystals on Si(111)

1993 ◽  
Vol 51 ◽  
pp. 844-845
Author(s):  
Xianghong Tong ◽  
Oliver Pohland ◽  
J. Murray Gibson
Keyword(s):  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Initial Growth ◽  
Surface And Interface ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Initial Stage ◽  
Effect Of Surface

The nucleation and initial stage of Pd2Si crystals on Si(111) surface is studied in situ using an Ultra-High Vacuum (UHV) Transmission Electron Microscope (TEM). A modified JEOL 200CX TEM is used for the study. The Si(111) sample is prepared by chemical thinning and is cleaned inside the UHV chamber with base pressure of 1x10−9 τ. A Pd film of 20 Å thick is deposited on to the Si(111) sample in situ using a built-in mini evaporator. This room temperature deposited Pd film is thermally annealed subsequently to form Pd2Si crystals. Surface sensitive dark field imaging is used for the study to reveal the effect of surface and interface steps.The initial growth of the Pd2Si has three stages: nucleation, growth of the nuclei and coalescence of the nuclei. Our experiments shows that the nucleation of the Pd2Si crystal occurs randomly and almost instantaneously on the terraces upon thermal annealing or electron irradiation.

Anisotropy of interfacial defects in the initial stage of MOVPE GaAs growth On Si

1990 ◽  
Vol 48 (4) ◽  
pp. 592-593
Author(s):  
C. Vannuffel ◽  
C. Schiller ◽  
J. P. Chevalier
Keyword(s):  
Early Stage ◽  
Threading Dislocations ◽  
Mbe Growth ◽  
Detailed Mechanism ◽  
Si Substrates ◽  
Initial Stage ◽  
Interfacial Defects ◽  
Interfacial Dislocations ◽  
Step Growth ◽  
Essential Problem

Recently, interest has focused on the epitaxy of GaAs on Si as a promising material for electronic applications, potentially for integration of optoelectronic devices on silicon wafers. The essential problem concerns the 4% misfit between the two materials, and this must be accommodated by a network of interfacial dislocations with the lowest number of threading dislocations. It is thus important to understand the detailed mechanism of the formation of this network, in order to eventually reduce the dislocation density at the top of the layers.MOVPE growth is carried out on slightly misoriented, (3.5°) from (001) towards , Si substrates. Here we report on the effect of this misorientation on the interfacial defects, at a very early stage of growth. Only the first stage, of the well-known two step growth process, is thus considered. Previously, we showed that full substrate coverage occured for GaAs thicknesses of 5 nm in contrast to MBE growth, where substantially greater thicknesses are required.

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