Electrophoretic molecular communication with piecewise constant electric field

This paper studies a novel electrophoretic molecular communication (EMC) framework utilizing a piecewise constant electric field. EMC is a particular type of molecular communication that exploits electric fields to induce the movement of charged particles to enhance communication performance. Our previous work proposed an EMC framework utilizing a time-varying electric field that exponentially changes; however, the field with such a complicated shape might be challenging to be implemented in practice. Thus, this paper proposes a new EMC approach exploiting a piecewise constant electric field that can be readily implemented via, e.g., an on/off switch method. We formulate two optimization problems to design the electric field based on different objectives: minimizing a mean squared error and minimizing a bit interval. The solutions of each, such as optimal on-off timings and corresponding strengths of the constant electric fields, are obtained through the Lagrange multiplier approach and the geometric programming, respectively. The Monte Carlo simulation results verify that the proposed piecewise constant electric field significantly reduces the bit error rate relative to the constant field benchmark while performing less well, but not significantly, than the exponential field benchmark

Retrospective study of alveolar ridge preservation compared with no alveolar ridge preservation in periodontally compromised extraction sockets

Background To minimize alveolar bone resorption, alveolar ridge preservation (ARP) has been proposed. Recently, interest in improving the feasibility of implant placement has gradually increased, especially in situations of infection such as periodontal and/or endodontic lesions. The aim of this study was to investigate if ARP improves feasibility of implant placement compared with no ARP in periodontally compromised sites. Secondary endpoints were the necessity of bone graft at the time of implant placement and implant failure before loading at ARP compared with no ARP. Material and methods This retrospective study was performed using dental records and radiographs obtained from patients who underwent tooth extraction due to chronic periodontal pathology. Outcomes including the feasibility of implant placement, horizontal bone augmentation, vertical bone augmentation, sinus floor elevation, total bone augmentation at the time of implant placement, and implant failure before loading were investigated. Multivariable logistic regression analysis was performed to examine the influence of multiple variables on the clinical outcomes. Results In total, 418 extraction sites (171 without ARP and 247 with ARP) in 287 patients were included in this study. The ARP group (0.8%) shows significantly lower implant placement infeasibility than the no ARP group (4.7%). Horizontal and vertical bone augmentations were significantly influenced by location and no ARP. Total bone augmentation was significantly influenced by sex, location, and no ARP. Conclusion ARP in periodontally compromised sites may improve the feasibility of implant placement. In addition, ARP attenuate the severity of the bone augmentation procedure

Novel Porous Transport Layers with Through Pores for Polymer Electrolyte Membrane Electrolyzers

Development of cost-effective porous transport layers (PTLs) for polymer electrolyte membrane (PEM) electrolyzers is crucial for the implementation of clean energy systems. In this thesis, novel PTLs with through pores have been investigated. Limited mass transport in the in-plane direction was observed in through pore PTLs, using in operando synchrotron X-ray radiograph. Furthermore, the limited in-plane mass transport led to dehydration of the catalyst layer (CL). Therefore, the placement of through pores play a critical role in the performance of PEM electrolyzers. Next, through pore PTLs consisting of woven meshes were studied. The contact resistance between the woven mesh PTL and the CL dominated performance losses, and smaller pore sizes improved the contact resistance. Stacking meshes with different pore sizes resulted in inhomogeneous compression of the CL, significantly degrading the PEM electrolyzer performance. The results from this thesis contribute to the development of cost-effective PTLs for next generation PEM electrolyzers.M.A.S

Propagation of High Power and Short Electromagnetic Wave in Nonlinear Dispersive Media

This project concerns the development of a numerical technique to model high power and short electromagnetic wave propagation in nonlinear dispersive media

Exeprimental Verification of Cyclopentane Hydrates with Guest Molecules for Potential Applications to Desalination and Gas Storage

In this study, flue gas, consist of CO2 (10%) + N2 (90%) and CO2 (20%) + N2 (80%), was injected into initial sH hydrate, formed with 2,2-dimethylbutane (Neohexane, NH) and CH4 (99.95%) gas for CH4 recovery and CO2 sequestration. The four- phase (H-LW-LNH-V) equilibrium line shift after the replacement verified that flue gas was successfully replaced with the CH4 in the sH hydrates. The 13C NMR confirmed that the CH4-flue gas replacement reaction proceeded without structural transition and the CO2 molecules also occupied the cages of sH hydrates. Stability conditions and heat of dissociation values after the replacement were measured using a high pressure micro-differential scanning calorimeter (HP ?? -DSC) to confirm the extent of the replacement. During the CH4 - flue gas replacement in sH hydrates, there was no significant heat flow change associated with the dissociation and formation of hydrates. This study revealed that the CH4 – flue gas replacement in sH hydrate could successfully proceed without structural transition and noticeable hydrate lattice destruction

Monitoring Arsenic Species Content in Seaweeds Produced off the Southern Coast of Korea and Its Risk Assessment

Seaweed, a popular seafood in South Korea, has abundant dietary fiber and minerals. The toxicity of arsenic compounds is known to be related to their chemical speciation, and inorganic arsenic (iAs) is more detrimental than other species. Due to the different toxicities of the various chemical forms, speciation analysis is important for evaluating arsenic exposure. In this study, total arsenic (tAs) and six arsenic species (arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, and arsenocholine) were analyzed in 180 seaweed samples. Although there were differences between seaweed species, the concentration of tAs was detected at levels ranging from 1 to 100 µg/g, and the distribution of six arsenic species differed depending on the seaweed species. No correlation between the concentration of iAs and tAs was found in most seaweed species. Through statistical clustering, hijiki and gulfweed were seen to be the seaweeds with the highest ratios of iAs to tAs. Using the iAs concentration data from the arsenic speciation analysis, a risk assessment of seaweed intake in South Korea was conducted. The margin of exposure values showed no meaningful risk for the general population, but low levels of risk were identified for seaweed consumers, with high intakes of gulfweed and hijiki