Chany Lee

Wax moth, Galleria mellonella, high density lipophorin receptor: alternative splicing, tissue-specific expression, and developmental regulation

A lipophorin (Lp) receptor cDNA from the fat body of Galleria mellonella (Lepidoptera) was cloned and sequenced. This is the first result in this order, Lepidoptera. It showed the pattern of the VLDL receptor belonging to the LDL receptor family. Sequence homology with other Lp receptors in insects, Locusta migratoria and Aedes aegypti, was 70 and 61%, respectively and each domain was highly conserved. Polyclonal anti-Lp receptor antibody prepared against expressed Lp receptor fragment between ligand binding domain and EGF-precursor homology domain (R305-D549 of amino acid residues) specifically detected the Lp receptor. Through immuno-blotting, the Lp receptor of larval fat body has an approximate molecular mass of about 97 and 110 kDa under non-reducing and reducing conditions, respectively. This result was in agreement with that of the ligand-blotting. The variant Lp receptors were expressed in the fat body of G. mellonella; one is an Lp receptor which lacks 84 bp of O-linked sugar domain and the other is a full length form of the Lp receptor. Both forms were detected by the polyclonal anti-Lp receptor antibody. The Lp receptor from the fat body of G. mellonella was differently expressed depending on the tissue and the developmental stage with specific abundance in prepupal stage. A steroid hormone, 20-hydroxyecdysone (20-HE) plays a crucial role in insect development. With regards to this conception, day 1-2 last instar larvae were treated with 20-HE and drastic induction of the Lp receptor was observed 48 h after treatment. It was also observed that cholesterol caused an induction of the Lp receptor.

Multifunctional transducer using poly (vinylidene fluoride) active layerand highly conducting poly (3,4-ethylenedioxythiophene) electrode: Actuator and generator

Monomorph and bimorph multifunctional transducers such as actuators and generators were fabricated using a piezoelectric poly (vinylidene fluoride) (PVDF) films as the active layer and a highly conducting poly (3,4-ethylenedioxythiophene)∕poly (4-styrenesulfonate) [PEDOT∕PSS (DMSO for solvent)] as the electrode. In order to enhance the adhesion of the films, either the PVDF films or PEDOT∕PSS (DMSO) electrodes were modified using an ion-assisted-reaction (IAR) method. The direct (generator) and inverse piezoelectric (motor) effects as well as the pyroelectric effect in the PVDF-PEDOT∕PSS based devices were observed. The tip displacement of the 12mm by 30mm bimorph device made with the PEDOT∕PSS (DMSO) electrodes was 3.5mm at the resonance frequency with an appled potential of 40Vrms. The sinusoidal output voltage of the bimorph type generator consisting of the PVDF active layers and PEDOT∕PSS (DMSO) electrodes increased with increasing tip displacement induced by a vibrator. A maximum output voltage of 4....

High energy (MeV) ion-irradiated π-conjugated polyaniline: Transition from insulating state to carbonized conducting state

High energy (MeV)C2+,F2+, and Cl2+ ions were irradiated onto π-conjugated polyaniline emeraldine base (PAN-EB) samples. The energy of an ion beam was controlled to a range of 3–4.5MeV, with the ion dosage varying from 1×1012 to 1×1016ions∕cm2. The highest dc conductivity (σdc) at room temperature was measured to be ∼60S∕cm for 4.5MeV Cl2+ ion-irradiated PAN-EB samples with a dose of 1×1016ions∕cm2. We observed the transition of high energy ion-irradiated PAN-EB samples from insulating state to conducting state as a function of ion dosage based on σdc and its temperature dependence. The characteristic peaks of the Raman spectrum of the PAN-EB samples were reduced, while the D-peak (disordered peak) and the G peak (graphitic peak) appeared as the ion dose increased. From the analysis of the D and G peaks of the Raman spectra of the systems compared to multiwalled carbon nanotubes, ion-irradiated graphites, and annealed carbon films, the number of the clusters of hexagon rings with conducting sp2-bonded carb...

Computer-Aided Performance Evaluation of a Multichannel Transcranial Magnetic Stimulation System

We have evaluated a multichannel transcranial magnetic stimulation (TMS) system using realistic simulations based on the boundary element method (BEM). We investigated various configurations and types of stimulation coils by means of quantitative measures such as targeting accuracy and field concentration. The simulation studies applied to four different head-brain models suggest improved coil types yielding enhanced targeting accuracy and concentrated evoked electric field distribution

Precise Estimation of Brain Electrical Sources Using Anatomically Constrained Area Source (ACAS) Localization

This paper proposes a new parametric source model to precisely estimate brain electrical source distribution from electroencephalogram (EEG) or magnetoencephalogram recordings. In the proposed approach, only four free parameters need to be evaluated for each anatomically constrained area source to express both spatial locations and extensions of brain electrical activities on cortical surface. The feasibility of the proposed model is verified through the applications to realistic EEG simulations and epilepsy patients data

Compatibility studies of blends of a thermotropic liquid crystalline polymer and flexible chain polymers by application of Flory's lattice theory

Abstract Florys lattice theory has been applied to the polymer blends containing a thermotropic liquid crystalline polymer (LCP) and flexible chain polymers. The phase behavior of blends of a thermotropic LCP and a flexible chain polymer at melt processing temperature can be evaluated by two quantitative parameters: the polymer–polymer interaction parameter ( χ 12 ) and the degree of disorder ( y / x 1 ). From the results of the model calculation, it has been found that the miscibility is increased with the increase of the degree of disorder ( y / x 1 ) of the LCP and with the decrease of the degree of polymerization ( x 1 m and/or x 2 ). The simulated spinodal curve of ternary polymer blends containing a thermotropic LCP and two flexible chain polymers has been calculated using the lattice theory. When three pairs of binary polymer blends are immiscible, the coexistence curve of the three phases appears for the ternary blend having similar values of χ ij among component polymers. When the LCP is immiscible with two flexible chain polymers, and also when the two flexible chain polymers are miscible with each other, the strong effect of anisotropy of the LCP is observed in the simulated spinodal curve. When three pairs of binary polymer blends are miscible, a phase separation is also observed due to the |Δ χ | effect.

COMETS2: An advanced MATLAB toolbox for the numerical analysis of electric fields generated by transcranial direct current stimulation

BACKGROUND Since there is no way to measure electric current generated by transcranial direct current stimulation (tDCS) inside the human head through in vivo experiments, numerical analysis based on the finite element method has been widely used to estimate the electric field inside the head. In 2013, we released a MATLAB toolbox named COMETS, which has been used by a number of groups and has helped researchers to gain insight into the electric field distribution during stimulation. The aim of this study was to develop an advanced MATLAB toolbox, named COMETS2, for the numerical analysis of the electric field generated by tDCS. NEW METHOD COMETS2 can generate any sizes of rectangular pad electrodes on any positions on the scalp surface. To reduce the large computational burden when repeatedly testing multiple electrode locations and sizes, a new technique to decompose the global stiffness matrix was proposed. RESULTS As examples of potential applications, we observed the effects of sizes and displacements of electrodes on the results of electric field analysis. The proposed mesh decomposition method significantly enhanced the overall computational efficiency. COMPARISON WITH EXISTING METHODS We implemented an automatic electrode modeler for the first time, and proposed a new technique to enhance the computational efficiency. CONCLUSIONS In this paper, an efficient toolbox for tDCS analysis is introduced (freely available at http://www.cometstool.com). It is expected that COMETS2 will be a useful toolbox for researchers who want to benefit from the numerical analysis of electric fields generated by tDCS.

Working memory deficit in patients with restless legs syndrome: an event-related potential study

OBJECTIVE The aim of this study was to investigate whether there is a working memory (WM) deficit in restless legs syndrome (RLS) patients, by studying the Sternberg WM task of event-related potential (ERP). METHODS Thirteen drug-naive RLS patients and 13 healthy age-matched controls with no sleep disturbances participated in the present study. P300 ERP was recorded during Sternberg WM task using digits as mnemonic items. P300 amplitudes and reaction times were compared between groups (RLS vs. control) considering brain regions (frontal, central, and parietal) and memory load sizes (two, three, and four) as within-subject factors. Clinical and sleep-related variables were correlated with P300 amplitude. RESULTS The reaction time in RLS patients was significantly longer than controls over all memory load sizes. The P300 amplitude at parietal regions in RLS patients was significantly lower than in controls regardless of memory load sizes, which was significantly negatively correlated with duration of RLS history in RLS patients. CONCLUSION Our study suggests that patients with severe RLS have WM deficits. Furthermore, negative correlation of P300 amplitudes with the duration of RLS illness suggests that cerebral cortical dysfunction in RLS patients results from repeated RLS symptom attacks.

Causal influence of epileptic network during spike-and-wave discharge in juvenile myoclonic epilepsy

Electroencephalographic (EEG) characteristic of juvenile myoclonic epilepsy (JME) is spike-and-wave discharge (SWD), which is dominant in the frontal region. However, activity in the parietal area, including the precuneus, has also been documented for several seconds before and during SWD. The aim of this study was to identify the role of the parietal region, especially the precuneus, and to clarify the causal dynamics among cortical regions during SWD. EEGs were obtained from seven patients with JME. Each SWD was divided into six distinct temporal phases: spike onset, spike peak, slow-wave onset, slow-wave ascending, slow-wave peak, and slow-wave descending phases. Based on the cortical current source distribution and the results of a previous study, we selected the medial frontal, orbitofrontal, anterior cingulate, and mesial temporal cortices and the precuneus as regions of interest (ROIs). To assess epileptic networks and the causal relationships among ROIs during SWD, the directed transfer function (DTF), a measure of multivariate causality, was calculated for each phase of SWD. During spike onset, the maximal outdegree region in all patients was the precuneus. The spike-peak and slow-wave onset phases did not show a consistently dominant outflow region. Outflow from the anterior cingulate cortex was dominant in four patients during the slow-wave ascending phase, and the precuneus showed the maximal outdegree in six patients during the slow-wave peak. In the slow-wave descending phase, four patients showed maximal outflow from the temporal cortex. Our findings suggest that the precuneus is likely a key region for SWD despite the small amount of neural activity observed. The precuneus was the region with the maximal outdegree during both the spike onset and slow-wave peak phases, indicating that SWD in JME is initiated and sustained by a network involving the frontal cortex, precuneus, and thalamus.

Point Collocation Mesh-Free Method Using FMLSRKM for Solving Axisymmetric Laplace Equation

In this paper, the fast moving least square reproducing kernel method (FMLSRKM) for solving the axisymmetric Laplace problem is proposed. To maximize the advantages of FMLSRKM, a point collocation scheme is used. The accuracy of the proposed method is verified by applying it to a test electrostatic model with analytic solution, and the electric potential distribution in the arc region of a gas circuit breaker is also analyzed as a practical application.