An experimental ball-milling study was performed to compare the deagglomeration behavior and the evolution of the particle size distribution with increasing milling time of two relatively coarse WC powders used for the production of cemented carbide cutting tools. The WC-powders were found to have distinctly different particle size distributions and particle morphologies prior to milling. Lab-scale WC samples were made using a range of different process parameters and milling times. These were then analysed by means of microscopy, laser light scattering, gas adsorption BET analysis and X-ray powder diffraction, XRD, to attain particle size distribution, specific surface area and a mean crystal size, respectively. The results suggested a linear relation between log(particle size) and log(milling time) between 10 and 80 hours milling. The viscosity was shown to have a minor effect on the milling efficiency. Both the number of collisions of milling balls per unit time as well as the kinetic energy of the milling ball affected the size reduction; more collisions or higher energy resulted in a higher milling efficiency. The evaluation of the effect of the process parameters on milling efficiency was facilitated by the use of simple scaling factors. For example, all milling curves for samples with different WC amounts coincided when rescaling the milling time using a scaling factor based on the weight of the WC and milling balls. The same scaling factor could be used with success for rescaling the results from different trials obtained with laser light scattering, gas adsorption and XRD. The results of this work are useful for future work on modeling of the milling process which should lead to more accurate predictions of the outcome of milling unit operations.

Approximately 80% of pharmaceutical products and the ingredients required for their manufacture are in powder form. The solid dosage form (tablets and capsules) is manufactured by either dry-blending of fine powder ingredients or combining the ingredients in a wet granulation step, followed by drying. Arching, ratholing, caking, segregation and flooding are some of the commonly encountered flow problems in the handling of fine powders. These problems lead to losses worth thousands of dollars at production scale. Poor powder flowability is a consequence of the combined effects of many variables, including improper equipment design, particle size, size distribution, shape, moisture content and surface texture. In the present work, a systematic study has been performed to determine the relationship between the flowability of fine powders and their physical properties of mean size and size distribution, density and shape.<p> Flowability studies were done on six different powders: the NutraSweet® Brand sweetener (aspartame), Respitose ML001, Alpha-D-Lactose monohydrate, the pharmaceutical binder Methocel (R) F50 Premium Hydroxypropyl methylcellulose- HPMC, a placebo pharmaceutical granulate, and common pastry flour. Scanning electron microscopy (SEM) and stereomicroscopy were used for particle shape and size analysis. Particle size distribution was determined using the laser light scattering technique. Powder flowability was measured using shear strength, angle of repose, and tapped-to-bulk density measurements. A novel method of measuring the dynamic angle of repose using electrical capacitance tomography (ECT) was developed. <p> Analysis of the images from microscopy revealed that the particles of aspartame and HPMC powders were elongated, the particles of ML001, pastry flour and lactose monohydrate powders were irregular, and the particles of placebo granulate were nearly spherical. Particle size was found to be the most reliable indicator of powder flowability, with decreasing particle size corresponding to lower flowability; however other parameters such as particle elongation and irregularity, were also found to have an influence on powder flowability. Although HPMC and pastry flour had similar particle sizes, they exhibited differences in flowability. This can be explained by the greater irregularity of the flour particles. Particle irregularity may cause mechanical interlocking between the particles, thus reducing powder flowability. ECT was found to be a promising non-intrusive tool for the measurement of the dynamic angle of repose. Unlike other methods for the measurement of dynamic angle of repose, the results obtained from ECT were not influenced by the effect of end caps. The present technique could be used by pharmaceutical industries in process analytical technology (PAT) for the detection and elimination of potential flow problems early in the manufacturing process.

Barley grain is an important source of energy and protein for ruminant animals. However, feeding must be carefully managed to avoid maladies caused by the rapid breakdown of barley starch in the rumen. The development of slower degrading barley for ruminants may alleviate health problems associated with barley grain consumption. Selection for hard endosperm may result in slower starch degradation and improved feed quality. The objectives of this study were to: examine the effect of grain hardness, variety and environment on dry matter disappearance rate (DMDR); identify accurate and efficient hardness selection tools; and study environmental effects, inheritance and heritability of hardness.<p>To study grain hardness and genetic and environmental effects on DMDR, two genotypes grown at multiple locations in 2004 were analyzed for Single Kernel Characterization System (SKCS) hardness, by scanning electron microscopy (SEM), and for in situ DMDR. Genotype by environment interaction influenced DMDR, while neither SKCS hardness nor SEM analysis accurately differentiated DMDR between genotypes. <p>Eight genotypes were grown at multiple locations during 2003 and 2004 to study grain hardness measurement methodology, and genetic and environmental effects on hardness. Genotypes were analyzed for SKCS hardness, milling energy, endosperm light reflectance, feed particle size, protein and beta-glucan. Hardness measurements ranked genotypes similarly across environments. Feed particle size was correlated with milling energy but not other hardness measurements. Hardness measurements appeared to be influenced by protein and beta-glucan.<p>To examine the inheritance and heritability of barley grain hardness, 245 double haploid (DH) genotypes and parents, grown in 2003 and 2004, were analyzed for SKCS hardness, milling energy, protein, beta-glucan, with 100 evaluated for light reflectance. The population exhibited normal distributions for SKCS hardness, milling energy, protein and beta-glucan, suggesting quantitative inheritance for these traits with no apparent epistatic gene interaction. Narrow-sense heritability was 0.75 for SKCS hardness and 0.41 for protein. Light reflectance was not normally distributed, suggesting complementary gene interaction. Broad-sense heritability was 0.53.<p>Barley grain hardness is highly heritable and an efficient tool in making selections in a breeding program. However, breeding for high beta-glucan and protein may be better selection criteria for indirect selection of DMDR.

The fibrous barley hull is the main reason for barleys low available energy relative to corn. Barley grain contains hydroxycinnamic acids (mainly ferulic acid (FA) and ñ-coumaric acid (PCA)) which are cross-linked to polysaccharides, therefore, limit cell wall degradability in the rumen. Paricle size of barley grain also affects the digestion of barley in the rumen. The objective of this study was to evaluate a set of barley varieties grown in Saskatchewan (Canada) and provided by Crop Development Center (CDC, Canada) and find a variety with low hull, FA, PCA and fiber content, while maintaining large particle size after mechanical processing, and having high nutrient availability.<p> Three studies were conducted to determine the content of barley hull, FA, PCA, neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) in various barley varities. Mean/median particle size of the barley grain after coarse dry-rolling was also determined. The relationships among these parameters and the digestibility of barley grain in ruminants were then assessed. Six barley varieties (AC Metcalfe, CDC Dolly, McLeod, CDC Helgason, CDC Trey and CDC Cowboy) from samples grown in three years (2003, 2004 and 2005) were evaluated in each study.<p> The first study determined the original content of barley hull, FA, PCA, NDF, ADF, ADL, and mean/median particle size of barley grain and evaluated the effects of barley variety. The results showed barley variety had a significant impact on the chemical and physical profiles of barley grain, with CDC Helgason and CDC Dolly showing relatively lower content of barley hull, FA, PCA, NDF, ADF, ADL, hemicellulose and cellulose, and moderate mean/median particle size, whereas McLeod and CDC Cowboy showed the opposite.<p> The second study involved two consecutive trials. Trial 1 was to assess differences in the in situ rumen degradability of dry matter (DM), FA, PCA, NDF, ADF and ADL at 12 and 24 h of rumen incubations. Results revealed that CDC Dolly consistently showed relatively lower rumen residues of DM, FA, PCA, NDF, ADF and ADL at 12 and 24 h, with McLeod being opposite. Barley variety displayed some effects on the digestibility of DM, FA, PCA, NDF, ADF and ADL at 12 and 24 h. Since CDC Dolly demonstrated relatively less content of hull, FA, PCA, NDF, ADF, ADL and mean/median particle size and higher rumen digestibility among the six barley varieties, while McLeod was the opposite, CDC Dolly and McLeod were selected for the third trial in order to compare differences in the rumen degradation kinetics of DM, FA and PCA. Trial 2 did not show significant differences in effective degradation of DM, FA, except for PCA. In general, CDC Dolly exhibited better degradability of DM, FA and PCA than McLeod.<p> The third study analyzed the correlation and regression between the original content of barley hull, FA, PCA, NDF, ADF, ADL and mean/median particle size in barley grain and rumen residual content of the corresponding parameters at 12 and 24 h of rumen incubation. Results showed that FA content in barley grain had a predominantly negative effect on DM degradability, while barley hull content affected the degradability of NDF and ADF.<p> In summary, the present studies show that hull and FA content in barley grain have negative effects on the degradability of barley grain in ruminants and also showed that CDC Dolly could be an ideal feed barley grain for ruminants due to its lower hull and FA content and higher rumen dry matter degradability.

A set of experiments was designed and performed to gain a fundamental understanding of various aspects of the segregated network concept. The electrical and mechanical properties of composites made from commercial latex and carbon black are compared with another composite made from a polymer solution. The percolation threshold of the emulsion-based composite is nearly one order of magnitude lower than that of the solution-based composite. The segregated network composite also shows significant improvement in both electrical and mechanical properties with low carbon black loading, while the solution-based composite achieves its maximum enhancement at higher carbon black loading (~25wt%). The effect of the particle size ratio between the polymer particle and the filler was also studied. In order to create a composite with an extremely large particle size ratio (> 80,000), layer-by-layer assembly was used to coat large polyethylene particles with the carbon black. Hyper-branched polyethylenimine was covalently grafted to the surface of polyethylene to promote the film growth. The resulting composite has a percolation threshold below 0.1 wt%, which is the lowest percolation threshold ever reported for a carbon-filled composite. Theoretical predictions suggest that the actual percolation threshold may be lower than 0.002 wt%. Finally, the effect of the emulsion polymer modulus on the segregated network was studied. Monodispersed emulsions with the different glass transition temperature were used as the matrix. The composites made using the emulsion with higher modulus show lower percolation threshold and higher conductivity. Higher modulus causes tighter packing of carbon black between the polymer particles. When the drying temperature was increased to 80°C, the percolation thresholds became closer between some systems because their moduli were very close. This work suggests modulus is a variable that can be used to tailor percolation threshold and electrical conductivity, along with polymer particle size.

The effects of abrasive particle size and tool surface roughness on tool and work wears of a polishing process were investigated. It was aimed to obtain a polishing condition that could result in a high work wear while the tool wear was low. An analytical study was first done to examine how the various operating conditions affected the wear rates of tool and work. It was done from a wear model developed by Su and Horng [1]. This model was further extended in the study to allow the wear rate analysis for an abrasive particle with ellipsoid shape. It was shown that an enhancement of abrasive particle size or tool surface roughness would increase the work wear while decrease the tool wear. Several sets of experiments were conducted to confirm the predictions of analytical study. It was shown that the experimental trends were the same as the analytical ones. Finally, the possible causes of observed phenomena and the limitations of the study were discussed.

To achieve predictive capability for complex environmental systems with coagulation and arsenic sorption, a unified improved coagulation model coupled with arsenic sorption was developed. A unified coagulation model coupled with arsenic sorption was achieved by the following steps: (1) an improved discretized population balance equation (PBE) was developed to obtain the exact solution of conventional coagulation, (2) the improved PBE was extended to an adjustable geometric size interval having higher numerical stability, accuracy, and computational efficiency than existing models for fractal aggregate coagulation that includes agglomeration and fragmentation, (3) a surface complexation equilibrium model and a sorption kinetic model was introduced to predict arsenic sorption behavior onto hydrous metal oxide surfaces, and (4) an improved discretized PBE was coupled with arsenic sorption kinetics and equilibrium models by aid of collision efficiency ?? depending on surface charge (potential) on the hydrous metal oxide particles, colliding particle size ratio, and fluid strain-rate in applied flow system. The collision efficiency ?? into the improved (r,r)ij(r,r)ijdiscretized coagulation model for fractal aggregate yielded a unified improved coagulation model coupled with arsenic sorption kinetics and the equilibrium model. Thus, an improved unified coagulation model could provide high statistical accuracy, numerical stability, and computational efficiency to enhance predictive capability for behavior of arsenic sorption and fractal colloid particle aggregation and break-up, simultaneously. From the investigation, it is anticipated that the unified coagulation model coupled with arsenic sorption kinetics and equilibrium will provide a more complete understanding of the arsenic removal mechanism and its application to water/wastewater treatment. Further, this coupled model can be applied to other water and wastewater treatment systems combined with sorption and filtration processes. These combined processes can be optimized by the coupled model that was developed in this study. By simulating the arsenic sorption and particle size distribution as a pretreatment before filtration (sand filtration or membrane filtration), the overall arsenic removal efficiency and operation cost can be estimated.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 111-116).

Thesis (M.S.)--University of Akron, Dept. of Mechanical Engineering, 2008. / "December, 2008." Title from electronic thesis title page (viewed 12/9/2009) Advisor, Jiang John Zhe; Faculty Readers, Joan Carletta, Dane Quinn; Department Chair, Celal Batur; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

Particle size and shape are important characteristics of the sediment which affects the adsorption of sediment-associate contaminants and nutrients onto the surface of sediment. This thesis characterized the spatial and temporal variation in size and shape of sediment particles in the Tobacco Creek Watershed. A strong correlation between the particle size of suspended sediment and stream discharge was observed. Spatial and temporal variation in size of suspended and channel bed sediment showed that particle size was significantly coarser at the upper reaches and following the rainfall events, but finer at the lower reaches and following the snowmelt events. Image analysis of coarser particles showed that rock fragments are not becoming rounded in short distances, but they reduced in size. The coarser materials from bedrock outcrops can be sources of fine-sized particle during transport. These findings have important implications for understanding suspended sediment dynamics transport in the study watershed.