Fabrication and characterization of nano carbon-based electrochemical double-layer capacitors

Porous electrode is a key component in electrochemical double layer capacitors (EDLCs), also called supercapacitors, which provides effective charge storage sites and ion transport channels along the electric double-layer interface between a solid electrode surface and liquid electrolyte. In particular, the micro-structure of an electrode is extremely important to optimize the ion’s transport channel and subsequently increasing the ion storage capacity on porous electrodes. This research focuses on three types of porous carbon materials, activated carbon (AC), graphene and single-walled carbon nanotube (SWCNT), with varying surface area and internal porosity as electrode materials. Depending on the type of carbon materials, three different fabrication methods, cast-coating, electrophotretic deposition (EPD) and vacuum filtration deposition, were developed to exploit the unique properties of electrodes. Their structural, electrochemical, thermodynamic properties were characterized, and the temperature/frequency-dependent capacitive and resistive behaviors were correlated to the microstructures, BET surface area, pore size and pore size distribution (PSD) of the electrodes. Under various operating temperatures between -30 °C and 60 °C and frequency operations, these electrochemical parameters were quantified using cyclic voltammetry (CV), constant current charging/discharging (CCD) measurements and electrochemical impedance spectroscopy (EIS). The differences in their temperature/frequency-dependent characteristics, including their current response to high scan rates, capacitance retention, resistance variation, and degradation of energy and power densities, were addressed by investigating ion kinetics and transport into the micro-, or meso-pores of the electrodes. An equivalent circuit model for an EDLC device was proposed through analyzing the EIS measurements. This model was developed based on the Grahame theory, while the effects of charge diffusion and the ion adsorption at the double-layer interface and bulk media were investigated. This circuit model, upon its validation against the EIS data, was successfully applied to characterize practical EDLC devices. Experimental results were obtained from different EDLC cells consisting of activated carbon-based electrodes and two distinct electrolytes, aqueous (H2SO4) and organic (Et4NBF4/PC). The model predicted the useful parameters (such as charge transfer, diffusion, adsorption and bulk media impedance) which help interpret electrochemical processes at the electrode/electrolyte interface. The quantitative dependence of impedance on the applied electrode potential was analyzed for the two electrolytes during charging/discharging, and its correlation with the internal resistance (referred ESR) was derived. Their temperature-dependent electrochemical properties were also investigated using a specified characterization procedure, and the capacitance, internal resistance and energy/power densities of the two capacitors were quantified. The temperature dependency of their impedances was analyzed through simulations of the EIS data by the proposed equivalent circuit model. The simulated impedances were then utilized to address the performance discrepancies between the two electrolytes

Deficits of case marker processing in persons with mild cognitive impairment

The purpose of the current study was to investigate whether persons with mild cognitive impairment (MCI) showed deficits in processing case markers compared to normal elderly adults (NEA). Results revealed that individuals with MCI presented significantly lower accuracy than the NEA group on a case marker processing (CMP) task. Both groups showed greater difficulties in the passive sentences than sentences with the transitive verbs. The current results suggested that individuals with early stage of dementia started presenting deficits in case marker processing compared to the control group

Location Tracking of Moving Crew Members for Effective Damage Control in an Emergency

In an emergency, the commanding officer may have limited information, and crew members may behave differently compared to how they behaved during training. In an emergency situation, if the commanding officer is aware of each crew member's location and role in that situation, he can disseminate orders expeditiously and precisely. To realise a faster and more precise dissemination of orders through better awareness of each crew member's location and role, real-time crew member tracking is needed. The technical feasibility of a real time crew-tracking system based on a wireless sensor network has been studied, with the intent to improve effective commanding in an emergency. Herein, location tracking was achieved using instrumentation consisting of ZigBee tags, routers, and gateways, which were used to record the location and role data of moving crew members on a full-scale ship.Defence Science Journal, 2011, 61(1), pp.57-61, DOI:http://dx.doi.org/10.14429/dsj.61.50

Malakoplakia of the Kidney Extending to the Descending Colon in a Patient with Secondary Adrenal Insufficiency: A Case Report

Malakoplakia is an uncommon but distinctive type of chronic granulomatous inflammation that occurs most commonly in the genitourinary tract, especially the urinary bladder. Most patients have associated conditions characterized by some degree of immunosuppression, as seen in solid-organ transplants, autoimmune diseases requiring steroid use, chemotherapy, chronic systemic diseases, alcohol abuse and poorly controlled diabetes. We report an unusual case of the renal malakoplakia that involved the perirenal space, extending to the descending colon in a 65-year-old Korean woman with secondary adrenal insufficiency and diabetes mellitus

Heating temperature prediction of concrete structure damaged by fire using a Bayesian approach

A fire that occurs in a reinforced concrete (RC) structure accompanies a heating temperature, and this negatively affects the concrete material properties, such as the compressive strength, the bond between cement paste and aggregate, and the cracking and spalling of concrete. To appropriately measure the reduced structural performance and durability of fire-damaged RC structures, it is important to accurately estimate the heating temperature of the structure. However, studies in the literature on RC structures damaged by fire have focused mostly on structural member tests at elevated temperatures to ensure the fire resistance or fire protection material development; studies on estimating the heating temperature are very limited except for the very few existing models. Therefore, in this study, a heating temperature estimation model for a reinforced concrete (RC) structure damaged by fire was developed using a statistical Bayesian parameter estimation approach. For the model development, a total of 77 concrete test specimens were utilized; based on them, a statistically highly accurate model has been developed. The usage of the proposed method in the framework of the 500 ◦C isotherm method in Eurocode 2 has been illustrated through an RC column resistance estimation application

Model eye imaging by closed-loop accumulation of single scattering (CLASS) microscopy

‘Closed-loop accumulation of single scattering (CLASS)’ microscopy provides novel solutions to the problems of light scattering and aberration in optical imaging, providing increased imaging depth while maintaining diffraction limited resolution. This method has a great potential to increase imaging depth and resolution of current eye imaging. In this presentation, the strength and weakness of the CLASS microscopy over the current adaptive optical microscopy will be discussed. Important factors to apply CLASS microscopy to eye imaging and the possibility to imaging retina in turbid condition will be discussed by using model eye

Differential associations of central and brachial blood pressure with carotid atherosclerosis and microvascular complications in patients with type 2 diabetes

BACKGROUND: We examined the relationship between central blood pressure (BP), brachial BP with carotid atherosclerosis and microvascular complications in type 2 diabetes mellitus (T2DM). METHODS: We recruited 201 patients who were evaluated for central BP, brachial BP, carotid ultrasonography, brachial-ankle pulse wave velocity (baPWV), ankle-brachial index (ABI) and microvascular complications. Central BP were calculated using a radial automated tonometric system. RESULTS: Agreement between central BP and brachial BP was very strong (concordance correlation coefficient between central and brachial SBP = 0.889, between central and brachial PP = 0.816). Central pulse pressure (PP) was correlated with mean carotid intima-media thickness (CIMT), baPWV and ABI, whereas brachial PP was borderline significantly correlated with CIMT. The prevalence of nephropathy(DN) and retinopathy(DR) according to the brachial PP tertiles increased, the prevalences of microvascular complications were not different across central PP tertiles. In multivariate analysis, the relative risks (RRs) for the presence of DR were 1.2 and 4.6 for the brachial PP tertiles 2 and 3 when compared with the first tertile. Also, the RRs for the presence of DN were 1.02 and 3 for the brachial PP tertiles 2 and 3 when compared with the first tertile. CONCLUSIONS: Agreement of central BP and brachial BP was very strong. Nonetheless, this study showed that higher brachial PP levels are associated with increased probability for the presence of microvascular complications such as DR/DN. However, there are no associations with central SBP and central PP with microvascular complications. Central BP levels than brachial BP are correlated with surrogate marker of macrovascular complications

Vav1 inhibits RANKL-induced osteoclast differentiation and bone resorption

Vav1 is a Rho/Rac guanine nucleotide exchange factor primarily expressed in hematopoietic cells. In this study, we investigated the potential role of Vav1 in osteoclast (OC) differentiation by comparing the ability of bone marrow mononuclear cells (BMMCs) obtained from Vav1-deficient (Vav1−/−) and wild-type (WT) mice to differentiate into mature OCs upon stimulation with macrophage colony stimulating factor and receptor activator of nuclear kappa B ligand in vitro. Our results suggested that Vav1 deficiency promoted the differentiation of BMMCs into OCs, as indicated by the increased expression of tartrate-resistant acid phosphatase, cathepsin K, and calcitonin receptor. Therefore, Vav1 may play a negative role in OC differentiation. This hypothesis was supported by the observation of more OCs in the femurs of Vav1−/− mice than in WT mice. Furthermore, the bone status of Vav1−/− mice was analyzed in situ and the femurs of Vav1−/− mice appeared abnormal, with poor bone density and fewer number of trabeculae. In addition, Vav1-deficient OCs showed stronger adhesion to vitronectin, an αvβ3 integrin ligand important in bone resorption. Thus, Vav1 may inhibit OC differentiation and protect against bone resorption