Sieve fraction samples

In considering the correlation results, it is well to keep in mind the range of fractionation, as indicated by the values of the r89,95 ratio, shown by the samples in question. For the Small Boy event most of the gross samples from the collecting stations in the local fallout field yielded values of 189,95 in the range between 0.1 and 0.2. However, when cloud samples, sieve fraction samples, and samples from the peripheral stations are also considered, the range of the ratio runs from about 0.01 to about 7.0. 

The strong increase in mean particle diameter of the sieve fraction 1.0-0.5 mm. for the coal with 32.2% volatile matter cannot be explained on the basis of the relationships discussed. The unusually high swelling ability in this case is caused by a very high proportion of exinite (21%) in the sample and the correspondingly very small proportion of inertinite (9). 

Standing-Crop Particles. Standing-crop, noncolloidal, particulate matter was sampled by using two techniques 1, niskin casts followed by filtration onto track-etched filters and 2, serial sieve fractionation in-line with continuous-flow centrifugation, which enabled the collection of gram quantities of suspended particles. 

SatnpCe Preparation. Seventy grams of sample, previously calcined at 538°C, was dispersed in about 125 mL of sodium metaphosphate solution and "wet screened" using a sieve stack of 250, 270 and 325 mesh, 8-inch diameter sieves. The sieves were washed with water until the effluent was free of any particulate and then rinsed with acetone to de-water. After air drying, the contents of each sieve were transferred to a porcelain dish and the material was recalcined at 538°C. Appropriate weights taken during this procedure allowed for the determination of percent moisture in the starting material and sieve analysis relative to the appropriate sieve fractions. The total +325 mesh material was recombined and mixed for the test. 

The basic idea of sieve analysis is very simple, a sample with a predetermined weight is placed on the top sieve and will be divided into multiple sieve fractions by the shaking, tapping, vibration, or air movements of the sieve instrument. The shaking. 

Care must also be taken to ensure that particle size distributions are adequate as selected particle size distributions will achieve greater homogeneity in reference materials especially when very low sample intakes are used for measurements. This is extremely important for environmental reference materials such as soils, sediments, etc., and is optimally achieved by jet-milling with ultra-fine classification of particles. With this technique, which is non-contaminating, fast and well-controlled, the sieved fraction below 2 mm of the material is ground by... 

Fig. 44. Scanning electron microscopy images sieved fractions. GMK nebulizer with an of AI2O3 particles sampled from a 1% suspen- impactor 3 mm from the orifice. Aerosol gas sion itself and from the aerosol produced flow rate 1 L/min, pumping rate 2 mL/min.

Sulfation of both zirconia s was performed by stirring 4.0 g (32.46 mmol) of each zirconia sample with 20 mL 0.5 M H2SO4 for 3 h and drying at 433 K for 16 h (no filtration). Sieve fractions (500-850 m) were calcined in a flow of dry air (50 mL/min) at 773 K for 3 h (heating/cooling rate 10 K/min). The catalysts were isolated from the reactor as well as stored under dry air prior to analysis and application. 

The gas-phase tram-alkylation reaction was performed in an automated micro-flow apparatus containing a quartz fixed-bed reactor (i d. 10 mm) at lO Pa [16 vol% benzene (1, p.a., dried on molsieve), 3.2 vol% diethylbenzene (2, consisting of 25% ortho, 73% meta, 2% para isomers, dried on molsieve), N2 balance (50 mL/min), WHSV =1.5 h ] with 2.0 mL of the tube reactor filled with catalyst particles (500-850 pm sieve fraction, typically 1.4 g). Two separate saturators were connected to the inlet of the reactor for the supply of 1 and 2. The partial vapor pressure of 1 and 2 was controlled by adjusting the temperature of the saturator-condensers and the N2 flow rate. After equilibration for 30 min at the applied reaction temperatures (473 K and 673 K, heating rate 10 K/min) within a dry N2 flow (50 mL/min), benzene (1) and diethylbenzene (2) were passed throu the reactor. To prevent condensation of both reactants and products prior to GC analysis [Hewlet Packard 5710 A, column CP-sil 5CB capillary liquid-phase siloxane polymer (100% methyl) 25 m x 0.25 mm, 323 K, carrier gas N2, FID, sample-loop volume 1.01 pL], tubes were heat-traced (398 K). FID sensitivity factors and retention times were determined using ethene (99.5 %, dried over molsieve) and standard solutions of 1, 2, and ethylbenzene (3, 99%) in methanol (p.a.). The conversion of 2 was measured as a function of time [8]. 

We mounted samples of feed coal in epoxy resin under hydraulic pressure as described by Cole and Berry (2). An apparatus and procedure for vacuum-mounting the fragile chars was developed ana is described elsewhere (8). Samples of pretreated coal and hydrogasification residue were sieved, and tests were made on the sieve fractions to avoid error from size segregation. 

C) in an air-fluidized bed. An analysis of the two chars is shown in Table I. The char was sized 18 X 35-mesh sieve fraction. The sample weight in any given run was 1.5-2.5 grams. The sample bucket was constructed of 100-mesh stainless steel screen. 

Air-dried soil was passed repeatedly through a 2-mm sieve and quartered to produce material with a grain size less than 0.5 mm. The sieved fraction was then dried at 105°C to a constant weight and stored in counting vessels of volume 125 cm and known geometry for gamma-spectrometric analysis. Prior to X-ray fluorescence (XRF) analyses, sieved and dried soil samples were pressed into pellets. 

Centurione (1993) recommends an initial 15 kg clinker sample, which is then quartered to 2.5 kg and sieved. The sieved fractions are crushed, sieved into 2.4-, 0.6-, and 0.3-mm fractions, and blended. A 50-gram sample is taken for microscopy, XRF, and chemical determination of free lime. 

A representative sample of the coarse wet-sieved fraction (>125 pm) is mounted on a labeled, glass microscope slide with epoxy resin, having an index of refraction (n) of 1.55 to 1.56, or balsam fir resin n = 1.537) as described below, and the limestone particles are counted microscopically to determine their percentage. Counting techniques are given additional discussion later in this chapter. 

Fig. 84. Magnetization curves vs. T for three samples, two of them resulting from sieved fractions of the first, after grinding. Solid lines are Shoenberg fits (cf. sect. 7.3). (a) Equilibrium sample (crosses), r 5., = 92.2K. (b) Sieved fraction with grains <15 Rm (open circles), (c) Sieved fraction with grains >50 pm (solid circles). No changes of = 92.2 K and rc2 = 90.2K with grinding or grain size were found (see text). After...

The impact of particle size on the dissolution performance was also observed for amorphous ITZ Soluplus extrudates. Samples of defined sieve fractions as well as samples of the unmilled strands were compared (simulated gastric fluid, n=6). The results (Fig. 13.1 data not published) clearly showed that after 100 min, the API from milled particles with a mean particle size above 250 xm was fully dissolved, whereas the dissolution from finer particles was significantly slower and incomplete. The unmilled strands were steadily eroding resulting in almost 100 % dissolution after 330 min. For this formulation, coarser particles were more beneficial fhan finer grades, potentially as a result of polymer swelling or concurrent recrystallization effects. 

FR measurements In order to avoid effects of bed formation and particle size heterogeneity samples of narrow CNT sieve fractions were distributed evenly over a glass-wool plug, placed in the sample holder of the batch-type FR system. A detailed description of the FR system is given in ref [22]. Samples were pre-treated in situ in high vaemun at 300 °C for 1 hour. Then, sorption equilibrium was established between the adsorbent and the sorptive alkane. The temperature and pressure of the FR measurements... 

Fig. 1 shows FR spectra for the neopraitane difilusion in sieve fractions of MWCNT-81 sample. When the characteristic time of periodic modulation approaches the time constant of the transport process, resonance occurs, which is indicated by the appearance of an inflexion and a peak in the in-phase and out-of-phase component curves, respectively. In Fig. 1 the component curves of the FR spectrum meet asymptotically at high frequencies. The theoretical analysis of the FR measurement suggested the appearance of this relative curve position is characteristic for rate-controlling diffusion process. However, the rate-controlling transport resistance can not be assigned on the basis of the FR results only to the transport in the macro, meso or micropores of the sample. 

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