Size and Structure

Pastor G M, Dorantes-Davila J and Bennemann K H 1989 Size and structural dependence of the magnetic properties of small 3d-transition metal clusters Phys. Rev. B 40 7642... 

Determination of Controlling Rate Factor The most important physical variables determining the controlhng dispersion factor are particle size and structure, flow rate, fluid- and solid-phase diffu-sivities, partition ratio, and fluid viscosity. When multiple resistances and axial dispersion can potentially affect the rate, the spreading of a concentration wave in a fixed bed can be represented approximately... 

A disconnection which produces two identical structures or two structures of approximately the same size and structural complexity is of high merit. Such disconnections may involve single or multiple bonds. 

In semi-crystalline polymers at least two effects play a role in the diffusion of the reactive endgroups. Firstly, the restriction in endgroup movement due to the lowering of the temperature, which usually follows an Arrhenius type equation. Secondly, the restriction of the molecular mobility as a result of the presence of the crystalline phase whose size and structure changes on annealing. 

Priesner, C. (1980). H, Staudinger, H, Mark und K, H, Meyer - Thesen zur Grofie und Struktur der Makromolekiile [H, Staudinger, H, Mark and K, H, Meyer — Theories about the Size and Structure of Macromolecules], Weinheim Verlag Chemie. 

Isoenzymes (isozymes) Enzymes that are very similar to one another in size and structure but with differences in catalytic ability. 

In addition to the degree of hydrophilicity of the solubilizates, their size and structure, the size of the host microregions, or the occurrence of specific processes must be taken into account in order to rationalize the driving forces of the solubilization process and of the solubilization site within water-containing reversed micelles [25,138,139],... 

The ability to produce threads, discs and spheres of defined size and structure will be of great importance when the very promising initial results from catalytic studies are applied on a larger scale. Processes using heterogeneous catalysts require the ability to control particle size and shape in order to ensure good mixing of all the reaction components, and separations after reaction. 

Pal B, Torimoto T, Iwasaki K, Shibayama T, Takahashi H, Ohtani B (2004) Size and structure-dependent photocatalytic activity of jingle-beU-shaped silica-coated cadmium sulfide nanoparticles for methanol dehydrogenation. J Phys Chem B 108 18670-18674... 

The catalytic performance of metal depends on the kinds of metal and supports, size and structure, and addition of other element(s). Thus, many trial and errors have been carried out in order to develop industrial catalysts. Even now, this is true for the research and development of practical catalysts. 

It is said that the 21st century is the age of nanotechnology since nanoparticles are applicable to an increasing number of areas. Therefore, this research field will occupy the much attention of scientists. Precisely controlling the primary size and structure of metallic nanoparticles, i.e., size, shape, crystal structure, and composition, however, is... 

Hybrid density functional calculations have been carried out for AU-O2, Au-CO, Aui3, AU13-O2, Au -CO, AU13-H2, and AU55 clusters to discuss the catalytic behavior of Au clusters with different sizes and structures for CO oxidation [179]. From these calculations, it was found that O2 and CO could adsorb onto several Au model systems. Especially, icosahedral Aun cluster has a relatively weak interaction with O2 while both icosahedral and cubooctahedral Aui3 clusters have interactions with CO. These findings suggest that the surfaces of the Au clusters are the active sites for the catalytic reactions on the supported and unsupported Au catalysts. 

Figure 6. Au particles deposited on monodispersed hematite particles different in size and structure (a) monocrystalline ellipsoid, (b) monocrystalline pseudocube, and (c) monocrystalline platelet. Flematite particles were also prepared by the authors.

How do particle size and structure influence catalytic activity ... 

Mukeijee S. 1990. Particle-size and structural effects in platinum electrocatalysis. J Appl Electrochem 20 537-548. 

Savinova ER. 2006. Size and structural effects in electrocatalysis. Doctor of Science Dissertation, Boreskov Institute of Catalysis, Novosibirsk. 

Karyotypic Number, size, and structure of cell chromosomes. 

McMahon The subject hasn t arisen in our discussion, but we should mention homeobox (Hox) genes here. The current model of the profound role that these play is that they regulate sizes and structures. It is a powerful argument that the reason that our radius and ulna are a different size from our humerus is because of the Hox genes that somehow intrinsically control that system. In the absence of the Hox genes, what you get is the formation of the initial anlages but a failure of growth of those structures. 

The results of experiments with crude oil fractions in this study also suggest that several species were present in reaction interface. There are mainly long chain carboxylic acids. The difference in size and structure is expected to give them different pka values. As a result, different surface activity (i.e., IFT value) is obtained with different levels of alkali concentration. Crude oil fractions with lower surface activity only yield surface inactive salts that may appear as precipitates at the interface. 

In many cases there is an interaction between the carrier and the active component of the catalyst so that the character of the active surface will change. For example, the electronic character of the supported catalyst may be influenced by the transfer of electrons across the catalyst-carrier interface. In some cases the carrier itself has a catalytic activity for the primary reaction, an intermediate reaction, or a subsequent reaction, and a dual-function catalyst is thereby obtained. Materials of this type are widely employed in reforming processes. There are other cases where the interaction of the catalyst and support are much more subtle and difficult to label. For example, the crystal size and structure of supported metal catalysts as well as the manner in which the metal is dispersed can be influenced by the nature of the support material. 

Recently, ultrathin evaporated films have been used as models for dispersed supported metal catalysts, the main object being the preparation of a catalyst where surface cleanliness and crystallite size and structure could be better controlled than in conventional supported catalysts. In ultrathin films of this type, an average metal density on the substrate equivalent to >0.02 monolayers has been used. The apparatus for this technique is shown schematically in Fig. 8 (27). It was designed to permit use under UHV conditions, and to avoid depositing the working film on top of an outgassing film. ... 

With respect to size and structure, type I- and type II-PHA synthases are distinguished from type III-PHA synthases. Whereas type I- and type II-PHA synthases consist of only one type of subunit, type III-PHA synthases consist of two different types of subunits. The differences between type I- and type II-PHA synthases regarding the substrate specificity will be described in the next section. 

Groenzin, H., and Mullins, O. C., Molecular size and structure of asphaltenes from various sources. Energy Fuels, 2000. 14 pp. 677-684. 

Among the properties measured here, the settling rate is mainly a measure of the size of the floes and in later stages the compressibility of floes and floe networks, and the supernatant clarity is a measure of the size distribution of floes and size dependent capture of the particles and floes by the polymer. The sediment volume and the pulp viscosity on the other hand, are direct measures, not only of floe size and structure but also of adsorbed polymer layers. It is to be noted in this regard that it is this latter aspect which makes it possible to estimate the thickness of adsorbed polymer layers by measuring the viscosity of the medium and the suspension in the presence of polymers (20,21). This combination of effects is another reason one cannot always expect correlation between various flocculation responses. 

Microgels which have been prepared in emulsions or microemulsion have a more compact structure than those obtained by polymerization in solution. For microemulsion copolymerization, preferentially self-emulsifying comonomers, such as unsaturated polyesters, are used as polymerizable surfactants, because no emulsifier must be removed after the reaction. By choosing suitable monomer combinations the composition, size and structure of microgels can be widely varied, thus adjusting these macromolecules to special applications. 

The resulting overall picture of liquid water is that of a very dynamical macromolecular system, where clusters of different size and structure coexist in different subvolumes of the liquid and each has characteristic lifetimes and specific temperature dependences. In our opinion, if we would... 

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