Size crystalline

Quantitative determination of the major and minor minerals In geological materials Is commonly attempted by x-ray diffraction (XRD) techniques. Mineralogists use a variety of sophisticated and often tedious procedures to obtain semlquantltatlve estimates of the minerals In a solid sample. The mineralogist knows that XRD Intensities depend on the quantity of each mineral component In the sample even through expressions for conversion of signal Intensity to quantitative analysis often are unknown or difficult to determine. Serious difficulties caused by variables such as particle size, crystallinity, and orientation make quantification of many sample types Impractical. Because of a lack of suitable standards, these difficulties are particularly manifest for clay minerals. Nevertheless, XRD remains the most generally used method for quan-... 

The specific surface area of a solid is the surface area of a unit mass of material, usually expressed as m g . There is an inverse relationship between surface area and particle size. Massive crystals of hematite from an ore deposit (e. g. specularite) may have a surface area 1 m g". As particle size/crystallinity is governed largely by the chemical environment experienced during crystal growth, the surface area of a synthetic iron oxide depends upon the method of synthesis and that of a natural one, upon the environment in which the oxide formed. 

Control of the pH and temperature of the precipitating solution is important to provide optimised conditions for stoichiometric, homogeneous, fluorhydroxyapatite formation. Similar conditions and set-up can be used for the synthesis of fluoride-substituted apatite crystals with varying size, crystallinity and morphology depending on the preparation temperature [124] a purge of the synthesis system with nitrogen gas ensures the preparation of carbonate-free fluorhydroxyapatite at ambient temperature [125]. 

In the case of formulations intended for intravenous administration, size reduction of APIs to nanometer-sized particles render a sterile, aqueous dispersion of such particles infusible. Indeed, particle size reduction methodologies have advanced to the point where nanometer-sized crystalline API particles can be realized. This size reduction approach provides a valuable formulation alternative to the traditional formulation approach of ensuring that a drug is solubilized before intravenous administration. It alleviates the potential issues associated with utilizing high concentrations of aqueous compatible cosolvents and surfactants to solubilize the drug. 

As described in previous chapters in Part II, liquid-continuous impinging streams (LIS) has the feature of very efficient micromixing and can provide a uniform and controllable supersaturation environment for the crystallization process, favoring the production of uniformly large-sized crystalline also, it has been proved experimentally that, to an extent, LIS can enhance crystal-growth rate. For industrial application, Wu [237] designed and patented the impinging stream crystallizer, the structure of which is shown in Fig. 17.3. 

The special flow configuration of the perfect mixing-plug flow in series in the impinging stream crystallizer is more suitable to crystallization process and so it is much easier to prepare uniformly large-sized crystalline particles and... 

PAGE) under reducing conditions,9 followed by staining with Coomassie blue. This resolves different protein subunits according to size. Crystallins are well resolved by an 11% acrylamide gel following the protocol given below. 

From a mineralogy viewpoint, IDPs are aggregates of mostly sub-micron-sized crystalline silicates (olivine and pyroxene), amorphous silicates, sulfides, and minor refractory minerals, held together by an organic-rich, carbonaceous matrix. Large fractions, 30-60 wt%, of these IDPs are amorphous silicates, known as glass with... 

The effect of various stoichiometry VO2 powders on temperature and heat of phase transition has not been reported so far. In this paper, the heats and the temperatures of transition from VO196 to VO207 in the crystalline state were measured from DSC scans. The results are listed in Table 1, indicating that the heats of the oxygen-deficient VO2 are less than those of the oxygen-rich VO2, and the VO2 02 has the maximum transition heat. The transition temperature is increased about 10°C from VOi 95 to VO2.07- Those results are not consistent with the results observed by determination of electrical resistivity of monocrystals reported in the literature, and the results in the literature are also contradictory [16,17]. The IR spectra of various size, crystalline state and stoichiometry VO2 are observed, showing the effects of size, crystalline state and stoichiometry [18]. 

Fe(III) particles through oxidation of Fe(n) at sites different from the intra-subunit ferroxidase centers of H-chain ferritins. These sites involve glutamic acid residues 53, 56, 57 and 60, and face the inner cavity of the molecule. Because ferritins rich in 1-chains oxidize iron more slowly than H-chain ferritins, they form iron particles of greater average size, crystallinity, and magnetic ordering. ... 

A wide variety of materials have been implemented as abrasive particles in CMP processes. They include alumina, silica, ceria, zirconia, titania, and diamond. The effectiveness and suitability of these particles in CMP with particular applications are greatly influenced by their bulk properties (density, hardness, particle size, crystallinity etc.) and the surface properties (surface area, isoelectric electric point (lEP), OH content, etc.). This section will focus on the evaluation of alumina, silica, diamond, and ceria as the major abrasives used for the CMP of metals. 

Physical modification of the drugs (particle size, crystallinity, and crystal form)... 

In pharmaceutical development, technology transfer from laboratory scale towards industrialization is generally considered as a critical step. It is therefore necessary to anticipate during laboratory scale studies changes which may occur in drug product quality during scale up. To do so, it is important to identify and control the drug product characteristics (for instance particle size, crystalline form,.. ) which may affect its performances (such as dissolution kinetics, compressibility,...). 

Discuss the conditions of formation, particle size, crystallinity, moisture content, [Fe(III)/OHJ solid ratio, and thermodynamic stability of Fe(lll) oxyhydroxide solids such as ferrihydrite and goethite. What happens to the solution pH, stoichiometry, and solubility of such solids when they are precipitated and aged under acid versus under alkaline conditions ... 

PR By reaction of the elements in powder form in a protective atmosphere, like argon or vacuum at elevated temperature. Starting materials, their size, crystallinity, presence of defects, oxide films, and experimental conditions determine the reaction product, mechanism, and kinetics. 

Fig. 3 shows the difference that can occur when ascorbic acid tablets of the same composition are produced at the same pressure, but when the active substance consists of crystals of two different sizes (crystalline =... 

Fig. 10.35 INS spectra of bone and model compounds in the O—H stretching region, recorded by two groups of workers. Left spectra recorded on LRMECS (IPNS) [84] (a) nanometre sized crystalline hydroxyapatite (b) micron sized crystalline hydroxyapatite, (c) bovine bone mineral, (d) bone mineral from rat. Right spectra recorded on HET (ISIS) [85] (e) highly crystalline hydroxyapatite, (f) ox femur bone mineral, and (g) brushite CaHP04.2H20. The dashed vertical lines show the position of the hydroxyapatite peaks.

The reliability of much of the thermodynamic data is always questionable. The data are obtained in a number of different ways, some more reliable than others. For solid phases, the nature of the solid phases involved in the determination of the data may be different from those in the system from the point of view of grain size, crystallinity, defect structure, and composition. 

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