• Journal of Microbiology and Biotechnology
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• v.26 no.3
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• pp.503-510
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• 2016

The accumulation (internal and superficial distribution) of magnesium ions (Mg²⁺) by the green freshwater microalga Chlorella vulgaris (C. vulgaris) was investigated under autotrophic culture in a stirred photobioreactor. The concentrations of the three forms of Mg²⁺ (dissolved, extracellular, and intracellular) were determined with atomic absorption spectroscopy during the course of C. vulgaris growth. The proportions of adsorbed (extracellular) and absorbed (intracellular) Mg²⁺ were quantified. The concentration of the most important pigment in algal cells, chlorophyll a, increased over time in proportion to the increase in the biomass concentration, indicating a constant chlorophyll/biomass ratio during the linear growth phase. The mean-average rate of Mg²⁺ uptake by C. vulgaris grown in a culture medium starting with 16 mg/l of Mg²⁺ concentration was measured. A clear relationship between the biomass concentration and the proportion of the Mg²⁺ removal from the medium was observed. Of the total Mg²⁺ present in the culture medium, 18% was adsorbed on the cell wall and 51% was absorbed by the biomass by the end of the experiment (765 h). Overall, 69% of the initial Mg²⁺ were found to be removed from the medium. This study supported the kinetic model based on a reversible first-order reaction for Mg²⁺ bioaccumulation in C. vulgaris, which was consistent with the experimental data.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.2
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• pp.193-200
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• 2016

Sertraline, a selective serotonin reuptake inhibitor (SSRI), has been reported to lead to cardiac toxicity even at therapeutic doses including sudden cardiac death and ventricular arrhythmia. And in a SSRI-independent manner, sertraline has been known to inhibit various voltage-dependent channels, which play an important role in regulation of cardiovascular system. In the present study, we investigated the action of sertraline on Kv1.5, which is one of cardiac ion channels. The effect of sertraline on the cloned neuronal rat Kv1.5 channels stably expressed in Chinese hamster ovary cells was investigated using the whole-cell patch-clamp technique. Sertraline reduced Kv1.5 whole-cell currents in a reversible concentration-dependent manner, with an $IC_{50}$ value and a Hill coefficient of $0.71{\mu}M$ and 1.29, respectively. Sertraline accelerated the decay rate of inactivation of Kv1.5 currents without modifying the kinetics of current activation. The inhibition increased steeply between -20 and 0 mV, which corresponded with the voltage range for channel opening. In the voltage range positive to +10 mV, inhibition displayed a weak voltage dependence, consistent with an electrical distance ${\delta}$ of 0.16. Sertraline slowed the deactivation time course, resulting in a tail crossover phenomenon when the tail currents, recorded in the presence and absence of sertraline, were superimposed. Inhibition of Kv1.5 by sertraline was use-dependent. The present results suggest that sertraline acts on Kv1.5 currents as an open-channel blocker.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.11 no.1
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• pp.1-4
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• 2015

Diastema is thought to be a problem related to aesthetics, pronunciation, or malocclusion. Due to its extent and patient conditions, orthodontic treatment, prosthodontic treatment, and conservative direct resin restoration are the treatment options for diastema closure. Additional factors need to be considered when deciding on the most appropriate treatment of diastema, particularly for patients with cerebral palsy. A 13-year-old girl visited the Department of Pediatric Dentistry at Yonsei University Dental Hospital with a chief complaint of the large gap between her upper front teeth. After clinical and radiographic examinations, midline diastema of 4.5 mm, protrusive maxilla incisors, congenital missing teeth, retained primary teeth, etc. were identified. Prosthodontic treatment with intentional root canal treatment was not appropriate because of the patient's age. Dental spaces can be closed effectively via orthodontic appliances. However, additional prosthodontic and restorative intervention is unavoidable, which incurs significant costs and requires more time. Instead of orthodontic and prosthodontic treatment, direct resin restoration can address the chief complaint; these restorations are reversible, less harmful to other oral structure and teeth, relatively easy to apply, less expensive than other treatments, and require shorter office visits. Midline diastema can be treated in several ways. For diastema closure in patients with cerebral palsy, conservative resin restorations are a short, simple, and appropriate treatment compared with orthodontic or prosthodontic treatments.

• Journal of the Korean Electrochemical Society
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• v.2 no.2
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• pp.106-111
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• 1999

The effect of the MG on the electrochemical charge-discharge properties of $CaNi_5$ hydrogen storage alloys was investigated under Ar and $H_2$ atmosphere. $CaNi_5$ alloy was partially decomposed to CaO and Ni phase during the MG process. The decomposition of $CaNi_5$ alloy was enhanced by the MG process which leads to crash and reformation of oxide layer on the alloy surface. As the MG process time increased, initial discharge capacity of the electrode was reduced, but the decay rate of the capacity compared to $CaNi_5$ alloys was slower. It may be described that the degradation of $MG-CaNi_5$ electrode was caused by the reduction of the reversible hydrogen reaction sites and increasing polarization resistance of hydrogen adsorption resulted from phase decomposition and disorder during the MG process, and/or by hydroxide formation during the electrochemical charge-discharge cycles.

• Journal of Electrochemical Science and Technology
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• v.11 no.4
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• pp.384-391
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• 2020

Due to its characteristics of light weight, high energy density, good safety, long service life, no memory effect, and environmental friendliness, lithium-ion batteries (LIBs) are widely used in various portable electronic products. The capacity and performance of LIBs largely depend on the performance of electrode materials. Therefore, the development of better positive and negative materials is the focus of current research. The application of metal organic framework materials (MOFs) derivatives in energy storage has attracted much attention and research. Using MOFs as precursors, porous metal oxides and porous carbon materials with controllable structure can be obtained. In this paper, rod-shaped Co-MOF-74 was grown on Ni Foam (NF) by hydrothermal method, and then Co-MOF-74/NF precursor was heat-treated to obtain rodshaped Co₃O₄/NF. Ni Foam was skeleton structured, which effectively relieved. The change of internal stress changes and destroys the structural volume of the electrode material and reduces the capacity attenuation. Co₃O₄/NF composite material has a specific discharge capacity of up to 1858 mA h/g for the first time, and a reversible capacity of up to 902.4 mA h/g at a current density of 200 mA/g, and has excellent rate and impedance performance. The synthesis strategy reported in this article opens the way to design high-performance electrodes for energy storage and electrochemical catalysis.

• Journal of the Korean Chemical Society
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• v.64 no.2
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• pp.74-78
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• 2020

A push-pull conjugated dye (DCMP) was covalently immobilized on a silanized glass surface to produce a high sensitivity pH sensor film for operating in the acidic region. A pH-sensitive sensor film was prepared by photo-initiating copolymerization of a modified DCMP (DCMA), 2-hydroxyethyl methacrylate (HEMA) and triethylene glycol dimethacrylate on the silanized glass surface. The absorbance of the sensor film increased with increasing pH between pH 2.0 and 5.0, and the fluorescence intensity of the film also increased about 50 times with increasing pH in the same pH range. The sensor film was reversible and reproducible under acidic conditions. The sensor film showed a relatively short response time between 20-50 seconds and high selectivity for proton in the presence of various metal ions.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.3 no.1
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• pp.75-83
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• 2000

Cyclic vomiting syndrome(CVS) is a disorder of unknown etiology that is characterized by its clinical pattern of intermittent episodes of severe vomiting, similar in time of onset and duration, with no symptoms during the intervening period. By definition, CVS is an idiopathic disorder that requires exclusionary laboratory testing. Not only can it be mimicked by many specific disorders, eg, surgical, neurologic, endocrine, metabolic, renal, but within idiopathic CVS there may be specific subgroups that have different mechanisms. It has been reported that CVS usually begins in toddlers and resolves during adolescence. Migraine is also self-limiting episodic condition of children and the clinical features of migraine and CVS show considerable similarity. It is proposed that CVS is a condition related to migraine. This paper reports clinical courses of long term follow-up and reversible EEG changes in three patients whose history included CVS. Clinical situations of attack interval, duration and associated symptoms had changed variablely in each patients through long term follow-up period. Cyclic vomiting subsided in two cases. Abnormal delta activity was seen during episodes and resolved at follow-up, when the patient asymptomatic. The brain wave changes support the interpretation of CVS as a migraine variant.

• Structural Monitoring and Maintenance
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• v.1 no.3
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• pp.249-271
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• 2014

This paper presents a unique study of Structural Health Monitoring (SHM) for the maintenance decision making about a real life movable bridge. The mechanical components of movable bridges are maintained on a scheduled basis. However, it is desired to have a condition-based maintenance by taking advantage of SHM. The main objective is to track the operation of a gearbox and a rack-pinion/open gear assembly, which are critical parts of bascule type movable bridges. Maintenance needs that may lead to major damage to these components needs to be identified and diagnosed timely since an early detection of faults may help avoid unexpected bridge closures or costly repairs. The fault prediction of the gearbox and rack-pinion/open gear is carried out using two types of Artificial Neural Networks (ANNs): 1) Multi-Layer Perceptron Neural Networks (MLP-NNs) and 2) Fuzzy Neural Networks (FNNs). Monitoring data is collected during regular opening and closing of the bridge as well as during artificially induced reversible damage conditions. Several statistical parameters are extracted from the time-domain vibration signals as characteristic features to be fed to the ANNs for constructing the MLP-NNs and FNNs independently. The required training and testing sets are obtained by processing the acceleration data for both damaged and undamaged condition of the aforementioned mechanical components. The performances of the developed ANNs are first evaluated using unseen test sets. Second, the selected networks are used for long-term condition evaluation of the rack-pinion/open gear of the movable bridge. It is shown that the vibration monitoring data with selected statistical parameters and particular network architectures give successful results to predict the undamaged and damaged condition of the bridge. It is also observed that the MLP-NNs performed better than the FNNs in the presented case. The successful results indicate that ANNs are promising tools for maintenance monitoring of movable bridge components and it is also shown that the ANN results can be employed in simple approach for day-to-day operation and maintenance of movable bridges.

• Composites Research
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• v.16 no.2
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• pp.62-67
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• 2003

Interfacial properties and damage sensing for the carbon fiber/epoxy-amine terminated (AT)-polyetherimide (PEI) composite were performed using microdroplet test and electrical resistance measurements. As AT-PEI content increased, the fracture toughness of epoxy-AT-PEI matrix increased, and interfacial shear strength (IFSS) increased due to the improved fracture toughness by energy absorption mechanisms of AT-PEI phase. The microdroplet in the carbon fiber/neat epoxy composite showed brittle microfailure mode. At 15 phr AT-PEI content ductile microfailure mode appeared because of improved fracture toughness. After curing, the change in electrical resistance $\Delta\textrm{R}$) with increasing AT-PEI content increased gradually because of thermal shrinkage. Under cyclic stress, in the neat epoxy case the reaching time until same stress was faster and their slope was higher than those of 15 phr AT-PEI. The result obtained from electrical resistance measurements under curing process and reversible stress/strain was correspondence well with matrix toughness properties.

• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.4
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• pp.459-468
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• 1984

The currently accepted model of membrane structure proposes a dynamic, asymmetric lipid matrix of phospholipids and cholesterol with globular proteins embedded across the membrane to various degrees. Most phospholipids are in the bilayer arrangement and also closely associated with integral membrane proteins or loosely associated with peripheral proteins. Biological functions of membrane, such as membrane-bound enzyme functions and transport systems, are influenced by the membrane physical properties, which are determined by fatty acid composition of phospholipids, polar head group composition and membrane cholesterol content. Polar and non-polar region of the phospholipid molecule can interact, with changes in the conformation of a membrane-associated protein altering either its catalytic activity or the protein's interaction with other membrane proteins. Mammalian dietary studies attempted to change the lipid composition of a few cell membranes have shown comparisons, using essential fatty acid-deficient diets. In recent years, Clandinin and a few other workers have pioneered the study proving the influence of dietary fat fed in a nutritionally complete diet on composition of phospholipid classes of cell membrane. Modulation caused by diet fat was rapid and reversible in phospholipid fatty acyl composition of membranes of cardiac mitochondria, liver cell, brain synaptosome and lymphocytes. These changes were at the same time, accompanied by variety of membrane associated functions controlled by membrane-bound enzymes, tranporter and receptor proteins. The findings suggest the basic concept of the necessity of dietary fatty acid balance if consistency of optimal membrane structural lipid composition is to be maintained, as well as the overall inadequacy of describing the nutritional-biochemical quality of a dietary fat solely by its content of linoleic acid. Furthermore, they give light on the possible application to clinical and preventive medicine.