Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 80 for “"Crystal size"”.
-
Novel continuous crystallization configurations for improved yield, purity and controlled crystal size distribution
Continuous crystallization process has potential advantages such as lower cost and improved flexibility in pharmaceutical production when compared to batch crystallization. A good continuous crystallization process should achieve a high product yield and purity comparable to current batch …
-
Modeling and experimental validation of a single-feed semi-batch precipitation process
Crystallization is a widely practiced unit operation throughout the chemical and pharmaceutical process industries. Despite its widespread application, crystallization still suffers a disproportionate number of process difficulties due to the complexity of the steps involved in the process. In …
-
Modeling and Simulation of Antisolvent Crystallization: Mixing and Control
… the issues of mixing and control in antisolvent crystallization processes, and to aid the development of systematic and scientific design approaches. The first part presents the development of an algorithm that couples macromixing and micromixing models with the population balance equation. It …
-
Production of nanocrystalline rdx by ress : development and material characterization
… research was to investigate the effect of RDX crystal size reduction down to nano-scale dimensions on the sensitivity characteristics. Although size reduction of energetic crystals has been demonstrated often to result in a sensitivity reduction, the effect at the nano-scale particle size has …
-
Melamine phosphate as a component of intumescent coatings
… variations in its chemical constitution, and crystal shape and size, dependent upon the method of production. These crystal types have been incorporated with epoxy resin to produce intumescent coatings, which have been tested on a small scale fire testing device, designed and calibrated within …
-
Optimal Control of Antisolvent and Cooling Crystallization
Common quality requirements for crystallization products is so critical in the pharmaceutical industry, including the demands of the drug administration and customers (e.g. bioavailability, size uniformity, and polymorphic form) and the concern of the manufacturer for downstream processes such as …
-
Effects of Milk Fat, Homogenization, and Stabilizer-Emulsifier Blend on the Texture of Vanilla Ice Cream
… weeks by direct microscopic examination of ice crystal size and a trained sensory panel. Milk fat level influenced ice cream mix total solids, viscosity, freezing point, and draw temperature. The higher level (16%) of milk fat increased ice crystal size. It also effected the texture scores …
-
Evaluating the Time-Dependent Melting Behavior of Semicrystalline Polymers Through Strobl's 3-Phase Model
… of polymers can provide information on their crystallization mechanism. However, the origin of the time-dependent low endotherm, or annealing peak, and the extent of melting-recrystallization-remelting during heating are still debated. The crystallization and subsequent melting behavior of …
-
Finite element and population balance models for food-freezing processes
… to consider product quality by modeling the ice crystal size distribution (CSD) throughout the hardening process. This is achieved through the use of population balance equations (PBE). Crystal size and corresponding hardened ice cream coarseness can be predicted through the PBE model presented …
-
Effect of Emulsifiers and Food Gum on Non Fat Ice Cream
… were no differences (P> 0.05) in meltdown. Ice crystal sizes were evaluated for treatments F15, F25, S 15, S25, Hl5, H25, and C during wk 1 and 12 of storage. There was about a 10 μ increase (P < 0.0S) in mean crystal size for treatments when comparing wk 1 and 12. Mean ice crystal sizes for the …
-
Crystalization studies in hollow fiber devices
Crystallization was examined under a new perspective and in a flow environment much different from that available in currently used industrial devices. Three crystallization techniques were tested in the unique flow environment offered by hollow fiber devices. In addition, a new type of heat …
-
Polymorphism control and the formation of organic molecular nanocrystals
The formation of organic molecular nanocrystals is a topic of great interest in the pharmaceutical industry because of the potential increase in dissolution rate and solubility of organic crystals below 1 ptm and their potential use in drug products. Previous investigators have developed various …
-
The design, development and testing of a non-invasive continuous crystalliser system for the study of calcium oxalate crystallisation processes
… for conventional MSMPR analysis. Various crystalliser offtakes and six system designs were developed and tested to allow measurements using the thermostatted flow cell. The flow cell allows for continuous measurement of the sample dispersion using a noninvasive monitoring instrument - a …
-
Formation of RDX nanoparticles by rapid expansion of supercritical solution : in situ characterization by laser scattering
… Data on the sensitivity of RDX in the 10-1000 um crystal size range suggested that the impact sensitivity could be further reduced by reduction of the crystal size to the sub-micron or nano-scale (Armstrong, 1990). Recent research with nano-RDX obtained using Rapid Expansion of Supercritical …
-
A thermodynamic framework for the modeling and optimization of crystallization processes
Crystallization is a widely used chemical engineering separation unit operation process. Since this technique can produce high purity products it is used for the industrial production of many chemical compounds, such as pharmaceuticals, agrochemicals, and fine chemicals. The production of these …
-
Syntheses and Photophysical Studies of Two-Dimensional Hybrid Organic-Inorganic Semiconductors
… In this thesis, we first present cooling-induced crystallization to produce phase-pure 2D LHPs with controllable chemical compositions. Using single-crystal X-ray diffraction, we refined their crystal structures across temperatures and observed two phase transitions corresponding to structural …
-
DEVELOPMENT OF NOVEL DESIGN AND CONTROL APPROACHES FOR INTEGRATED CRYSTALLIZATION OPERATION AND SYSTEMS
Crystallization is an important separation and purification technique for a wide variety of solid products in pharmaceutical, food and fine chemical industries. The production of more than 90% of the active pharmaceutical ingredients (APIs) involves crystallization. Therefore, it is crucial to …
-
Modeling, optimization, and sensitivity analysis of a continuous multi-segment crystallizer for production of active pharmaceutical ingredients
… steady-state optimization of a new type of crystallizer for the production of pharmaceuticals. The multi-segment, multi-addition plug-flow crystallizer (MSMA-PFC) offers better control over supersaturation in one dimension compared to a batch or stirred-tank crystallizer. Through use of a …
-
Deformation and Transformation Mechanisms of Polybutene and Poly(vinylidene Fluoride)
… depending upon the orientation of the original crystalline lamellae comprising the spherulites with respect to the draw direction. Deformation of fresh PB thin film is accompanied by a transformation of tetragonal form to hexagonal form. Potassium permanganate etching and dark field microscopy …
Page 1 of 4