Characterization of Swirling Fluidized Bed

This dissertation is intended to conclude and summarize the overall milestone of Final Year Project, Characterization of Swirling Fluidized Bed. In recent years, the Swirling Fluidized Bed has been regarded as one of the novel designs in fluidization technology. This new technique features an annular-blade distributor which injects the fluidizing gas through a certain inclination, is capable of fluidizing the bed and at the same time causes swirling motion of particles in a circular trajectory. In the present work, the fluidization characteristics and hydrodynamics of a swirling bed are studied using experimental approach. The behavior of gas-particle interaction in a swirling bed in terms of operation regimes, trends of pressure drop across particle bed and hysteresis effects of bed pressure drop with increasing superficial velocity of gas, are explored by varying bed configurations. Three different sizes of spherical Polyvinyl chloride particle, two sizes in irregular shape and two sizes in cylindrical form, are used as bed material by considering four bed weights from 500 g to 2000 g, with increment of 500 g in each step, three blade overlap angles of 9°, 15° and 18°, for air superficial velocities up to approximately 3.5 m/s and two blade inclination of 10° and 15°. In this report, a well-structured review of the literature is constructed to compile the critical and substantive discoveries in the past researches. Furthermore, detailed research methodology and detailed analysis of experiment results are illustrated and expounded. The findings explicitly show that the solid particle size, shape, and bed weight are the major variables that give significant impact on the fluidized bed characteristics, while the blade dimension has relatively smaller effect on the bed behavior. This project has, hopefully, revealed how everything responds in SFB and this correlated relationship could be a precious benchmark in designing a reactor bed. As a conclusion, the research is intended to demonstrate the superiority of SFB over conventional bed. Through this exploration, the author sincerely hopes that this project will become an achievable reference volume for every practitioner in this field, spanning the boundary of various disciplines especially for fluidization engineering

Synthetic intestinal mucosal barrier using a hydrogel slab integrated microfluidic chip

The mucosal barrier lining along the intestinal tract plays a key role in metabolic and immunological homeostasis. Repeated disruption of the mucosal barrier integrity has been suggested to be a precursor event that derives inflammatory bowel diseases and colorectal cancer. Multiple in vitro platform technologies have been developed to understand the mucosal barrier function including trans-wells and microfabricated devices, but a static and vertical axis culture settings limits to simulate and observe dynamic complexity of the gut microenvironment. Here, we introduce a biomaterials engineering approach to create a synthetic mucosal barrier in a transverse manner for direct observation of cellular processes. A type I collagen hybridized polyacrylamide hydrogel supporting small molecular transport and epithelial cell adhesion was used as a framework and subsequently anchored covalently to a glass slide via silanization chemistry. Villous microstructures ~250µm in height were manufactured by casting the hydrogel precursor solution in a pre-designed, removable polydimethylsiloxane micropattern mold and polymerizing using UV light. After sealing the device with another glass slide, we increased the cellular and extracellular complexity of this microfluidic chip by sequentially introducing (i) HT-29 colon epithelial cells, (ii) mucin extracts from a pig intestine, (iii) bacteria, and (iv) human peripheral blood-derived mononuclear cells and co-cultured them in a single device. This modular in vitro microphysiological intestinal tissue model may serve as a translational platform to discover the biophysical etiology for disruption of the mucosal barrier and associated inflammatory diseases

Transient hydraulics and multiphase kick tolerance study to improve design of narrow margin well

Hydraulic and well control studies are the essential parts of well construction planning, especially for drilling of complex and challenging wells with narrow drilling margins. However, the complete applications of dynamic hydraulic analysis and multiphase kick tolerance studies in well design are scanty, which result in ineffective mud pressure management and extra cost spent on unnecessary casing strings, due to excessive emphasis on previous practices (steady-state model) with liberal sprinkling of safety factors. This research project was set out clearly to improve the well design for narrow margin field, in terms of hydraulics and well control. A deductive quantitative method constitutes major part of the research methodology, in which simulation of real case studies and interpretation were conducted. The dynamic hydraulics simulated equivalent circulating density (ECD) was compared with steadystate results in terms of accuracy and extensiveness in providing a good well design. In addition, the single bubble kick tolerance results which are commonly used by the industry in spreadsheet format were compared with the multiphase model results. Sensitivity studies were performed to understand the effect of each of the operational or well design parameters towards primary and secondary well control. As compared to steady-state hydraulics, transient model covers important parameters like pressure and temperature dependent fluid properties, thermophysical properties, detailed geometry description and operational effects, thus it is more representative to the operational ECD. Meanwhile, multiphase kick model is proven to be more effective for the evaluation of kick tolerance as it is able to provide the information of pressure development during a well control operation, from initial influx and shut-in until influx is circulated out of the well at the surface. This includes all phase transitions including dissolving of a gas kick in oil based mud and breakout of free gas when the gas contaminated mud reaches the bubble point at shallower depth in the well. The flow model is much more accurate and reliable than the over-conservative traditional single bubble theory

The full repertoire of Drosophila gustatory receptors for detecting an aversive compound.

The ability to detect toxic compounds in foods is essential for animal survival. However, the minimal subunit composition of gustatory receptors required for sensing aversive chemicals in Drosophila is unknown. Here we report that three gustatory receptors, GR8a, GR66a and GR98b function together in the detection of L-canavanine, a plant-derived insecticide. Ectopic co-expression of Gr8a and Gr98b in Gr66a-expressing, bitter-sensing gustatory receptor neurons (GRNs) confers responsiveness to L-canavanine. Furthermore, misexpression of all three Grs enables salt- or sweet-sensing GRNs to respond to L-canavanine. Introduction of these Grs in sweet-sensing GRNs switches L-canavanine from an aversive to an attractive compound. Co-expression of GR8a, GR66a and GR98b in Drosophila S2 cells induces an L-canavanine-activated nonselective cation conductance. We conclude that three GRs collaborate to produce a functional L-canavanine receptor. Thus, our results clarify the full set of GRs underlying the detection of a toxic tastant that drives avoidance behaviour in an insect

Can Derivative Information Predict Stock Price Jumps?

This study examines the predictability of jumps in stock prices using options-trading information, the futures basis spread, the cross-sectional standard deviation of returns on components in the stock index, and exchange rates. A stock price jump was defined as a large fluctuation in the stock price that deviated from the distribution thresholds of the past rates of return. This empirical analysis shows that the implied volatility spread between ATM call and put options was a significant predictor for both upward and downward jumps, whereas the volatility skew was less significant. In addition, the futures basis spread was moderately significant for downward stock price jumps. Both the cross-sectional standard deviation of the rates of return on component stocks in the KOSPI 200 and the won-dollar exchange rates were significant predictors for both upward and downward jumps

Trabecular Bone Organoid Model for Studying the Regulation of Localized Bone Remodeling

Trabecular bone maintains physiological homeostasis and consistent structure and mass through repeated cycles of bone remodeling by means of tightly localized regulation. The molecular and cellular processes that regulate localized bone remodeling are poorly understood because of a lack of relevant experimental models. A tissue-engineered model is described here that reproduces bone tissue complexity and bone remodeling processes with high fidelity and control. An osteoid-inspired biomaterial-demineralized bone paper-directs osteoblasts to deposit structural mineralized bone tissue and subsequently acquire the resting-state bone lining cell phenotype. These cells activate and shift their secretory profile to induce osteoclastogenesis in response to chemical stimulation. Quantitative spatial mapping of cellular activities in resting and activated bone surface coculture showed that the resting-state bone lining cell network actively directs localized bone remodeling by means of paracrine signaling and cell-to-cell contact. This model may facilitate further investigation of trabecular bone niche biology

Trabecular bone organoid model for studying the regulation of localized bone remodeling

Trabecular bone maintains physiological homeostasis and consistent structure and mass through repeated cycles of bone remodeling by means of tightly localized regulation. The molecular and cellular processes that regulate localized bone remodeling are poorly understood because of a lack of relevant experimental models. A tissue-engineered model is described here that reproduces bone tissue complexity and bone remodeling processes with high fidelity and control. An osteoid-inspired biomaterial-demineralized bone paper-directs osteoblasts to deposit structural mineralized bone tissue and subsequently acquire the resting-state bone lining cell phenotype. These cells activate and shift their secretory profile to induce osteoclastogenesis in response to chemical stimulation. Quantitative spatial mapping of cellular activities in resting and activated bone surface coculture showed that the resting-state bone lining cell network actively directs localized bone remodeling by means of paracrine signaling and cell-to-cell contact. This model may facilitate further investigation of trabecular bone niche biology