Publication size determination

Morrison, I.D. Grabowski, E.F. Herb, C.A. "Improved Techniques for Particle Size Determination by QELS", accepted for publication in Langmuir. 

Figure 7.3 UV versus LIF detection of the CE separation of a 53 base pair RT-PCR product from the RNA of the polio virus vaccine, Sabin 3. An Hae Ill-digested d>X174 DNA marker was coinjected with the PCR product for size determination—note the 72 bp fragment. The same Sabin 3 concentration was used for each analysis, whereas the marker total DNA concentration varied from 200 mg/mL for UV analysis, to 20 mg/mL for LIF analysis. Note the unambiguous pattern observed with LIF for the Sabin 3 fragment compared to UV detection of the same fragment. Full scale UV detection, 0.005 absorbance unit (AU) LIF detection, 10 relative fluorescence units (RFU). [Reproduced with permission from Schwartz et al., J Capillary Electrophor 1 36 (1994). Copyright ISC Technical Publications, Inc.]...

In a recent publication Dumeslc c.s. described adsorption and desorption measurements of H2 on Ni/Ti(>2 and Pt/Ti(>2 catalysts, which showed that a larger amount of H2 could be desorbed (after 15-20 h equilibration of these catalysts under about 40 kPa H2) than could be directly adsorbed (32). In agreement with our conclusions their explanation was that, apart from a fast H2 adsorption on the metal, hydrogen apparently also adsorbed slowly on the Ti02 support via a spillover process from metal to support. These authors noticed that the amounts of H2 desorbed from the M/Ti(>2 catalysts in the SMSI state were in fair agreement with metal particle sizes determined by X-ray line broadening and electron microscopy and suggested that H2 desorption could be used to estimate metal... 

McManus, J. M., 1988. Grain size determination and interpretation. In Tucker, M. (ed.) Techniques in Sedimentology. Blackwell Scientific Publications, London 63-85. 

Step 9.1 Identify the Effluent Discharge Points. Determine the points at which wastewater leaves the site. Wastewater may go to an effluent treatment plant, directly to a public sewer, or directly to a watercourse. One factor that is often overlooked in audits is the use of several discharge points. It is important to identify the location, type, and size of all discharge flows. Identify where flows from different unit operations or process areas contribute to the overall flow. In this way, it is possible to piece together the drainage network for the site. This can lead to startling discoveries of what goes where ... 

Either a liquid or a gas can be used as the carrier fluid, depending on the size and properties of the particles, but there are important differences between hydraulic (liquid) and pneumatic (gas) transport. For example, in liquid (hydraulic) transport the fluid-particle and particle-particle interactions dominate over the particle-wall interactions, whereas in gas (pneumatic) transport the particle-particle and particle-wall interactions tend to dominate over the fluid-particle interactions. A typical practical approach, which gives reasonable results for a wide variety of flow conditions in both cases, is to determine the fluid only pressure drop and then apply a correction to account for the effect of the particles from the fluid-particle, particle-particle, and/or particle-wall interactions. A great number of publications have been devoted to this subject, and summaries of much of this work are given by Darby (1986), Govier and Aziz (1972), Klinzing et al. (1997), Molerus (1993), and Wasp et al. (1977). This approach will be addressed shortly. 

Better procedures for determining particle sizes from X-ray diffraction are based on line profile analysis with Fourier transform methods. The average size is obtained from the first derivative of the cosine coefficients and the distribution of particle sizes from the second derivative. When used in this way, XRD offers a fundamental advantage over electron microscopy, because it samples a much larger portion of the catalyst. The reader is referred to publications by Cohen and coworkers for more details and examples [4,10,11],... 

In many cases the medium in which the molecules move is not homogeneous and the diffusion motion of the molecules is influenced by the structure of the medium. Examples are the diffusion of water and oil in porous rock or in water-oil emulsions. Many publications have shown that the NMR diffusion results can be used to quantitatively study the porous structure, like the determination of pore and droplet sizes, pore connectivity and pore hopping or of the surface to volume ratio of the pores. 

Fractionation of proteins according to size utilizing cross-linked dextran or polyacrylamide gel columns was first demonstrated by Porath and Flodin 63 in 1959. This technique has become the most widely accepted method for separation and molecular weight determination of hydrophilic and some hydrophobic macromolecules using aqueous buffers with or without organic modifier. While this technique might not be unique in its ability to resolve and separate proteins, it is one additional simple and effective tool in the chemist s armamentarium. The theories behind size-exclusion HPLC and size-exclusion chromatography at low pressure are identical and are described in several publications. 31 34 36 39 44 64 65 ... 

MIL-STD-1233 - Procedure for Determining Particle Size Distribution and Packing Den-siry of Powdered Material MIL-STD-1235 — Single and Multilevel Continuous Sampling Procedures and Tests for Inspection by Attributes 2.2 Other Publications See Spec, pp 1 2 3. REQUIREMENTS... 

Comparison of the pore size distribution determined by the present method with that from the classical methods such as the BJH, the Broekhoff-de Boer and the Saito-Foley methods is shown in Figure 4. Figure 5 shows a close resemblance of the results of our method with those from the recent NLDFT of Niemark et al. [16], and XRD pore diameter for their sample AMI. The results clearly indicate the utility of our method and accuracy comparable to the much more computationally demanding density functional theory. There are several other methods published recently (e. g. [21]), however space limitations do not permit comparison with these results here. It is hoped to discuss these in a future publication. 

Column specifications expressed as (length X ID, particle size manufacturer) when reported in original publication. n = number of determinations LoD = limit of detection CV = coefficient of variation. 

---