Search

In this study, an effective method for 5-HMF production from agarose, a biomass material derived from red-algae, is proposed. 5-HMF was produced from the decomposition of agarose by the catalytic action of a solid acid, Amberlyst 36, in dimethyl sulfoxide (DMSO), which is a polar aprotic solvent apt for providing a micro-aqueous environment. The moisture content in DMSO was found to be the governing factor for 5-HMF production, with an optimum level of 7.2% at which the 5-HMF yield was 62%, the highest level ever observed in the production of 5-HMF from agarose. DMSO was also found to protect 5-HMF, once produced, from rehydration in the present system. It was demonstrated that Amberlyst 36 could be repeatedly used in a packed-bed reactor, which was the prime objective of using a solid acid instead of a liquid acid as catalyst.

Over the last 30 years the extent of sea-ice covering the North Pole has declined about 15∼20% on average, and it is expected that by the end of the 21st century, vast areas of the Arctic Ocean will be ice-free during the summer season, thus, increasing the possibility of ship navigation across the Arctic Ocean. In this paper, we have developed a model of shipping for the Northwest Passage (hereinafter NWP) in northern Canada to determine whether ice thinning will make this route more economically viable when compared with the Panama Canal. Among the 7 routes of the NWP, Route 2 and Route 3 offer better navigational conditions than the others. However, Route 3 has a depth limit of only 10m, so here we use Route 2 which is suitable for deep draft navigation to carry on our analysis. Container ships of 4,500∼15,000 TEU under Hub and spoke mode, container shipping between Busan port and New York port is simulated for the Panama Canal and the NWP. This paper considers Canada's sovereignty in matters of navigation over the waters at the Arctic Archipelago, in the form of a toll fee for passage usage. We concluded that the NWP has an advantage over the Panama Canal if it is open for free international passage, regardless of ship size. However, if it is not free, its advantages depend on its toll fee. The lower the toll fee is, the more advantages the NWP will boast.

In this study, for high-performance indium-free metal oxide channel layer, we synthesize Zn-Sn-O (ZTO) precursor solutions in which formamide is incorporated as an additive for catalyzing the subsequent sol-gel reactions and the evolution of chemical structure. It is revealed that the formamide plays a critical chemical role in evolving a chemical structure with more oxygen-deficient oxide lattice and with less hydroxide, allowing for high field-effect mobility over 7 cm(2)/V·s. Furthermore, it is for the first time demonstrated that electrically active metal-oxide films can be patterned, using an air-brush printing technique, by directly depositing formamide-mediated ZTO-precursor solutions in patterned geometries.

The development of highly conductive, flexible metallic constituents in patterned geometries has been of paramount interest in various optoelectronic applications. Among a variety of materials, silver nanoparticles have been considered as candidates that meet the physical/chemical requirements for practical applications; but, the issues for applicability to roll-to-roll processes on inexpensive substrates have not been yet resolved. In this study, we demonstrate that the highly flexible, rollable, printable Ag structures, with an electrical resistivity of 8.0 μΩ cm, are easily formed on a timescale of 10−3 s on polyethylene terephthalate and paper substrates, by supplying highly intensive photon energies on olate-Ag nanoparticle assemblies. The precise control of the amount of carbon residues, by virtue of sophisticatedly adjustable input of photon energies, allows the formation of well-adhesive metallic films on plastic substrates, without incorporating any additional procedures, enabling extreme flexibility during 10 000 cycles with a bending radius of 1.5 mm. The continuous approach with a moving stage also suggests the potential toward a practical sintering process for instantly generating highly flexible, conductive metallic architectures in a large area.

Microgrids are autonomous low-voltage power distribution systems that contain multiple distributed energy resources (DERs) and smart loads that can provide power system operation flexibility. To effectively control and coordinate multiple DERs and loads of microgrids, this paper proposes a distributed intelligent management system that employs a multi-agent-based control system so that delicate decision-making functions can be distributed to local intelligent agents. This paper presents the development of a hardware-in-the-loop simulation (HILS) system for distributed intelligent management system for microgrids and its promising application to an emergency demand response program. In the developed HILS system, intelligent agents are developed using microcontrollers and ZigBee wireless communication technology. Power system dynamic models are implemented in real-time simulation environments using the Opal-RT system. This paper presents key features of the data communication and management schemes based on multi-agent concepts. The performance of the developed system is tested for emergency demand response program applications.

This paper describes the development of the pilot plant of distributed intelligent management system for a microgrid. For optimal control and management of microgrids, intelligent agents area applied to the microgrid management system. Each agent includes intelligent algorithms to make decisions on behalf of the corresponding microgrid entity such as distributed generators, local loads, and so on. To this end, each agent has its own resources to evaluate the system conditions by collecting local information and also communicating with other agents. This paper presents key features of the data communication and management of the developed pilot plant such as the construction of mesh network using local wireless communication techniques, the autonomous agent coordination schemes using plug-and-play functions of agents and contract net protocol (CNP) for decision-making. The performance of the pilot plant and developed algorithms are verified via real-time microgrid test bench based on hardware-in-the-loop simulation systems.

This paper deals with geometrical non-linear analyses of the tapered cantilever column subjected to the sub-tangential follower force at the free end. Cross-sections of the column whose flexural rigidities are functionally varied with the axial coordinate. The differential equations governing the elastica of such column are derived on the basis of the large deformation theory. These differential equations have three unknown parameters of the vertical and horizontal deflections and rotation at the free end. These differential equations are numerically solved by the iteration technique for obtaining three unknowns and elastica of the deformed column. For validating theories developed herein, laboratory scaled experiments are conducted.

This paper deals with a novel method for numerical analyses of the tapered geometrical non-linear beam with three unknown parameters, subjected a floating point load. The beams with hinged-movable end constraint are chosen as the objective beam. Cross sections of the beam whose flexural rigidities are functionally varied with the axial coordinate. The first order simultaneous differential equations governing the elastica of such beam are derived on the basis of the Bernoulli-Euler beam theory. A novel numerical method for solving these equations is developed by using the iteration technique. The processes of the solution method are extensively discussed through a typical numerical example. For validating theories developed herein, laboratory scaled experiments are conducted.

In the future, the individual entities of microgrids such as distributed generators and smart loads may need to determine their power generation or consumption in more economic ways. Intelligent agents can help the decision-making procedure of the entities by intelligent algorithms and state-of-the-art communication with central controller and other local agents. This paper presents the development of atable-top microgrid control system using multi-agent systems and also the demonstration of demand response programs during power shortage. In our table-top system, agents are implemented using microcontrollers and Zigbee wireless communication technology is applied for efficient data communication in the multi-agent system. The power system models of distributed generators and loads are implemented in the real-time simulator using Opal-RT system. The whole test system that includes real-time system simulation and agent hardware is implemented in the hardware-in-the-loop simulation framework. The performance of the developed system is tested for emergency demand response cases.

Well-aligned ZnO nanorods for the photoelectrode of dye-sensitized solar cells (DSSCs) were grown via a sonochemical method, and the heat-treatment effects on the dye adsorption in the DSSCs were studied. The heat treatment of well-aligned ZnO nanorods was performed at 200 ∼ 500 °C for 1 h, which was immediately followed by the dye adsorption. The dye amounts adsorbed in the ZnO nanorods were estimated from the UV-Vis absorbance by using Beer-Lambert’s law. The efficiency of the DSSCs with ZnO nanorods was measured to investigate the heat-treatment effects of ZnO nanorods on the dye adsorption properties. The heat-treatment of ZnO nanorods was found to yield a change in their dye adsorption ability, resulting in a change in the efficiency of the DSSCs.

Well-aligned ZnO nanorods for the photoelectrode of dye-sensitized solar cells (DSSCs) were grown via a sonochemical method, and the effects of their aspect ratios on the dye adsorption in DSSCs were studied. The control of the aspect ratio of well-aligned ZnO nanorods was performed by tuning the mole concentration of zinc acetate dehydrate in the range of 0.04–0.06M. The dye amounts adsorbed in the ZnO nanorods were estimated from the UV-Visible absorbance by using the Beer-Lambert law. The efficiency of DSSCs with ZnO nanorods was measured to investigate the effects of the aspect ratio of the ZnO nanorods on the dye adsorption properties. A change in the aspect ratio of the ZnO nanorods was founded to yield a change in their dye adsorption ability, resulting in a change in the efficiency of the DSSCs.

Multi-layered light scattering layer has been designed to improve the energy conversion efficiency of dye-sensitized solar cells (DSSCs) by scattering of the incident light. To enhance the light scattering properties, the surface of light scattering TiO2 particle was dual-coated with nano-sized Al2O3 and SiO2 particles by using a modified sol-gel method. Four kinds of the TiO2 electrodes with different thicknesses were fabricated and their photovoltaic effects on DSSCs were investigated. By increasing the thickness of light scattering layer, the total reflectance of working electrodes increased to 37%, resulting in an increase in the energy conversion efficiency up to 6.76%.

This paper deals with geometrical non-linear analyses of the tapered variable-arc-length beam, subjected to the combined load with an end moment and a point load. The beam is supported by a hinged end and a frictionless sliding support so that the axial length of the deformed beam can be increased by its load. Cross sections of the beam whose flexural rigidities are functionally varied with the axial coordinate. The simultaneous differential equations governing the elastica of such beam are derived on the basis of the Bernoulli-Euler beam theory. These differential equations are numerically solved by the iteration technique for obtaining the elastica of the deformed beam. For validating theories developed herein, laboratory scaled experiments are conducted.

This paper deals with minimum-weight beams built with the minimum volume of beam material that can sustain the subjected load. In order to build a minimum-weight beam, the geometry of the strongest beam is analyzed, for which the values of the maximum beam behaviors are minimized at the given volume of material. For the structural analysis of such a beam, the theorem of least work is employed, considering strain energies of both bending and shear. Further, deflection curves are obtained using the successive integration method. The strongest section ratios, as determined by both the maxi-mini stress and deflection, are obtained from the results of the structural analysis. The beam geometry of the minimum-weight beam, which is described by the taper type, side number, volume, and cross sectional depth, is determined from the given allowable stress and deflection. In numerical examples, three kinds of end constraint are considered: hinged-hinged, hinged-clamped, and clamped-clamped beams.

A dual-band planar antenna that was developed for wireless local area network (WLAN) application is presented in this article.The proposed antenna, which has two strip lines for resonance and a rectangular ring strip for matching, was designed to cover the popular frequency spectra of the 2.4 and 5 GHz WLAN bands. Also, an asymmetric ground and a rectangular slit in the ground are introduced to enhance the performance of the proposed antenna. The proposed antenna, which is capable of dual-frequency operation, is fed by a strip line. The obtained numerical results agree well with the experiment data. It was validated that the configuration can meet the demands of WLAN systems and effectively enhanced the impedance bandwidth to 16.8% for the lower band and 58.14% for the upper band when VSWR < 2. This article also presents and discusses the 2D radiation patterns and gains according to the results of the experiment. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26225

This paper deals with free vibrations of the tapered beams with the constant surface area. The surface area of the objective beams are always held constant regardless shape functions of the cross-sectional depth. The shape functions are chosen as the linear and parabolic ones. Ordinary differential equations governing free vibrations of such beams are derived and solved numerically for determining the natural frequencies. In the numerical examples, hinged-hinged, hinged-clamped and clamped-clamped end constraints are considered. As the numerical results, the relationships between non-dimensional frequency parameters and various beam parameters such as section ratio, surface area ratio, end constraint and taper type are reported in tables and figures. Especially, section ratios of the strongest beam are calculated, under which the maximum frequencies are achieved.

The vibration characteristics of fully and partially embedded piles with flexibly supported end carrying an eccentric tip mass are investigated. The pile model is based on the Bernoulli-Euler theory and the soil is idealized as a Winkler model for mathematical simplicity. The governing differential equations for the free vibrations of such members are solved numerically using the corresponding boundary conditions. The lowest three natural frequencies and corresponding mode shapes are calculated over a wide range of non-dimensional system parameters: the rotational spring parameter, the relative stiffness, the embedded ratio, the mass ratio, the dimensionless mass moment of inertia, and the tip mass eccentricity.

(-)-Epigallocatechin-3-gallate (EGCG), a major green tea polyphenol, was tested for in vitro cytotoxicity against human laryngeal epidermoid carcinoma of the larynx Hep2 cells. EGCG-induced apoptotic cell death accompanied by a change in the cell cycle. However, EGCG did not result in caspase activation, nor did a caspase inhibitor block cell death. Furthermore, EGCG caused no change in the intracellular levels of reactive oxygen species (ROS). The levels of p53 were increased in the EGCG-treated cells, with a corresponding decrease in Bcl-2 and Bid protein levels as well as an increase in the Bax level. In addition, EGCG induced the cytoplasmic release of cytochrome c from the mitochondria accompanied by a decreased mitochondrial membrane potential, and subsequently upregulated translocation of apoptosis-inducing factor (AIF) and endonuclease G (EndoG) into the nucleus during the apoptotic process. Taken together, these findings indicate that the p53-mediated mitochondrial pathway and the nuclear translocation of AIF and EndoG play a crucial role in EGCG-induced apoptosis of human laryngeal epidermoid carcinoma Hep2 cells, which proceeds through a caspase-independent pathway.

The differential equations governing out-of-plane free vibrations of the elastic, horizontally curved beams with variable curvature are derived and solved numerically to obtain natural frequencies and mode shapes for parabolic, sinusoidal and elliptic beams with hinged–hinged, hinged–clamped, and clamped–clamped end constraints, in which the effects of the rotatory and torsional inertias and shear deformation are included. Experimental measures of frequencies for several laboratory-scale parabolic models serve to validate the theoretical results.

This article presents an omni-tread snake robot that designed to locomote on narrow space and rough terrain. The omni-tread snake robot comprises three segment, which are linked to each other by 2 degrees of freedom joints for the pitch and yaw motion. Moving tracks on all four sides of each segment guarantee propulsion even when the robot rolls over. The 2 DOF joint are actuated by 2 servo motors which produce sufficient torque to lift the one leading or trailing segments up and overcome obstacles. This paper applies articulated steering technique to get omni-tread snake robot`s kinematics model.

This paper deals with the out-of-plane free vibrations of circular strips with linearly varying breadth. In deriving the differential equations for such strips, the effects of the rotatory and torsional inertias and shear deformation are considered. The differential equations are numerically solved to calculate the natural frequencies and mode shapes. In the numerical examples, three end constraints, i.e. clamped–clamped, clamped-hinged and hinged–hinged ends, are considered. The five lowest frequency parameters and mode shapes are presented. The effects of the rotatory and torsional inertias, and shear parameter on the natural frequencies are evaluated. Parametric studies are carried out for the influence of following parameters of the strip on the natural frequencies: subtended angle, section ratio, thickness ratio, and slenderness ratio. Also presented are the experimental validations of the seven lowest predicted natural frequencies. The natural frequencies obtained by this study agree well with those by the finite element method for both the flexural and torsional modes.

This paper deals with the application of the numerical differentiation using the differential quadrature(DQ) in the curved member-like structural analysis. Derivative values of the geometry of structure are definitely needed for analyzing the structural behavior. For verifying the numerical differentiation using DQ, free vibration problems of arch are selected. Terms of curvature composed with the derivatives of arch geometry obtained herein are agreed quite well with exact values obtained explicitly. Natural frequencies subjected to terms of curvature obtained by DQ are agreed quite well with those in the literature. The numerical differentiation using DQ can be practically utilized in the structural analysis.

The differential equations governing free vibrations of the elastic, parabolic arches with unsymmetric axes are derived in Cartesian coordinates rather than in polar coordinates. The formulation includes the effects of axial extension, shear deformation and rotatory inertia. Frequencies and mode shapes are computed numerically for arches with clamped-clamped, clamped-hinged, hinged-clamped and hinged-hinged ends. The convergent efficiency is highly improved under the newly derived differential equations in Cartesian coordinates. The lowest four natural frequency parameters are reported as functions of four non-dimensional system parameters: the rise to chord length ratio, the span length to chord length ratio, the slenderness ratio and the shear parameter. Typical mode shapes of vibrating arches are also presented.

Numerical methods for calculating both the natural frequencies and buckling loads of columns with intermediate multiple elastic springs are developed. In formulating the governing equations of the column, each elastic spring is modeled as a discrete Winkler foundation of the finite longitudinal length. By using this model, the differential equations governing both the free vibration and buckled shapes of the column are derived, which are solved numerically. The Runge–Kutta method is used to integrate the differential equations, and the determinant search method combined with Regula–Falsi method is used to determine the eingenvalues, namely, the natural frequencies and buckling loads. In the numerical examples, fixed–fixed, fixed-hinged, hinged-fixed and hinged–hinged end constraints are considered. The numerical results including the frequency parameters, mode shapes of free vibrations and buckling loads are presented in non-dimensional forms.

The governing differential equations for the out-of-plane, free vibration of circular curved beams resting on elastic foundations are derived and solved numerically. The formulation takes into consideration the effects of rotary inertia and transverse shear deformation. The lowest three natural frequencies are calculated for beams with hinged–hinged, hinged-clamped, and clamped–clamped end constraints. The effects of various system parameters as well as rotary inertia and shear deformation on the natural frequencies are investigated.

A numerical method is developed for calculating the buckling loads of tapered columns of regular polygon cross-section with constant volume and both clamped ends. The linear, parabolic and sinusoidal tapers are considered in numerical examples. From the numerical results, the strongest columns by the taper types and side numbers of regular polygon cross-sections are identified.

We investigated the photoelectrochemical effects on La ion-modified ZnO nanorods for dye-sensitized solar cells (DSSCs), preparing four kinds of samples grown in solutions with 0, 1, 2, and 3 at% of La precursors. It was found that La ion modifications lead to an increase in the lattice constant of ZnO nanorods, resulting in widening of their energy bandgap. I-V results tell that the photoelectrochemical properties increase in the order of 2, 1, 0, and 3 at% La ion-modified ZnO nanorod-based DSSCs. To further analyze and explain the experimental results, we measured absorbance, IPCE, and EIS and concluded that the DSSCs fabricated by using 3 at% La ion-modified ZnO nanorods exhibit better device performances such as Voc, Jsc, and efficiency, suggesting that the amount of La ions is a key parameter of La modified-DSSCs. The results can be explained by Burstein-Mott effects, vertical growth, and La oxide coating effects of the ZnO nanorods.

The differential equations governing free, in-plane vibrations of linearly elastic non-circular arches with non-uniform cross-section are derived and solved numerically to obtain frequencies and mode shapes. Numerical results are presented for the quadratic, parabolic, catenary and elliptic arches with hinged–hinged, hinged–clamped, and clamped–clamped end constraints. Three general taper types for a rectangular section are considered. Experimental measurements of frequencies and their corresponding mode shapes agree closely with those predicted by theory.

Numerical methods are developed for solving the elastica and the buckling load of simply supported tapered columns subjected to compressive end load. The linear, parabolic and sinusoidal tapers with the regular polygon cross-sectional shapes are considered, whose material volumes are always held constant. The column model is based on Bernoulli–Euler beam theory. The Runge–Kutta and Regula–Falsi methods are used to solve the buckling load and the postbuckling deflected shape vs load. Extensive numerical results, including the equilibrium paths, the shapes of elastica and the buckling loads are presented in non-dimensional forms. By varying the section ratio, the strongest columns are identified for each taper and cross-sectional shape.

The differential equations governing free, in-plane vibrations of non-circular arches, including the effects of rotatory inertia, shear deformation and axial deformation, are derived and solved numerically to obtain frequencies and mode shapes. The lowest four natural frequencies are calculated for the parabolic, elliptic and sinusoidal geometries with hinged–hinged, hinged–clamped, and clamped–clamped end constraints. A wide range of arch rise to span length ratios, slenderness ratios, and two different values of shear parameter are considered. The agreement with results determined by means of a finite element method is good from an engineering viewpoint.

Embryonic hypoxia/ischemia is a major cause of a poor fetal outcome and future neonatal and adult handicaps. However, biochemical cellular events in mouse embryonic stem (mES) cells during hypoxia remains unclear. This study investigated the underlying mechanism of apoptosis in mES cells under CoCl2-induced hypoxic/ischemic conditions. CoCl2 enhanced the expression of hypoxia-inducible factor-1α (HIF-1α) and the accumulation of reactive oxygen species in mES cells. The CoCl2-treated mES cells showed a decrease in cell viability as well as typical apoptotic changes, cell shrinkage, chromatin condensation, and nuclear fragmentation and an extended G2/M phase of the cell cycle. CoCl2 augmented the release of cytochrome c into the cytosol from the mitochondria with a concomitant loss of the mitochondrial transmembrane potential (ΔΨm) and upregulated the voltage-dependent anion channel. In addition, CoCl2-induced caspase-3, -8, and -9 activation and upregulation of p53 level, whereas downregulated Bcl-2 and Bcl-xL, a member of the anti-apoptotic Bcl-2 family in mES cells. Furthermore, CoCl2 led to the upregulation of Fas and Fas-ligand, which are the death receptor assemblies, as well as the cleavage of Bid in mES cells. These results suggest that CoCl2 induces apoptosis through both mitochondria- and death receptor-mediated pathways that are regulated by the Bcl-2 family in mES cells.

The differential equations governing free, in-plane vibrations of linearly elastic arches with variable cross-sections are derived and solve numerically for quadratic arches with three types of rectangular cross sections. Frequencies, mode shapes, cross-sectional load distributions, and the effects of rotatory inertia on frequencies are reported. Experimental measurements of frequencies and their corresponding mode shapes agree closely with those predicted by theory. The numerical methods presented here for computing for computing frequencies and mode shapes are efficient and reliable.

With the advance of ubiquitous computing environments, more convenient and personalized intelligent services can be possible. While we can enjoy comfortable life thanks to the upgraded broadband and fast internet, various types of adverse effects may be emerged at the same time. Among these side effects of information society, the leakage of personal data will be one of the most serious problems in modern society. From the business perspective, customer information needs to be protected and to be managed safely. And from the user perspective, users have to manage and protect their own and unique data by themselves. In Korea, the need to evaluate the level of protecting personal data in side of company as well as user is proposed. we have gotten to design the measure to evaluate that. The model is consisted of business sector, 6 indicators, and personal sector, 6 indicators.

The specific binding of HeLa cell factors to DNA sequences at the Epstein-Barr virus (EBV) latent origin of DNA replication was detected by gel shift experiments and DNase I footprinting analysis. These cellular proteins protected at least five discrete regions of the DNA replication origin. The viral protein required for EBV plasmid replication, EBV nuclear antigen 1 (EBNA-1), binds to specific sequences within the origin region. The HeLa cell proteins competed with EBNA-1 for binding to EBV origin DNA in vitro, leading to the possibility that these cellular proteins regulate EBV DNA replication by displacing EBNA-1 at the origin sites.

This study develops a contact model which is indispensable for the force generation in the virtual environment. For development of the contact model, we adopt the proxy concept and the Karnopp friction model therefore with the developed contact model we can generate the friction force included reaction force. Also this study develops a 2 D.O.F. remote wiping system. This system is composed of a 2 D.O.F. master manipulator, a force sensor equipped 2 D.O.F. slave manipulator and a real time controller. With the developed remote wiping system, this study identifies the frictional characteristic of the aluminum and acryl plate. And we used it as the dynamic friction coefficient of the developed contact model. This study shows the efficiency of the developed contact model by comparing a) the frictional characteristic of the haptic display simulation with the developed contact model with b) the frictional characteristic of the real aluminum and acryl plate.

In this paper we present the mechanical/electrical design of half-sized outdoor patrol robot CALEB I. The robots are designed to be operated by both remote control mode and autonomous mode. To patrol around buildings efficiently and safely, we implemented navigation algorithms based on GPS and odometer, and obstacle avoidance and traversal as well as posture stabilization. The robot offers autonomous surveillance for outdoor environments, which is proved by a set of experiments in outdoor environment.

This article presents an omni-tread snake robot, Caleb III, that designed to locomote on narrow space and rough terrain. The Caleb III comprises three segments, which are linked to each other by 2 degrees of freedom joints for the pitch and yaw motion. Moving track on all four sides of each segment assures propulsion even when the robot rolls over. The 2 D.O.F. joint is actuated by 2 servo motors which produces sufficient torque to lift the one leading or trailing segments up and overcome obstacles. This paper applies articulated steering technique to get Caleb III's kinematics model. We simulate the robot motion by the proposed kinematic model. And with the same parameters of the simulation we manage several types of motion experiments. Through the experiments we obtained the robot's Cartesian coordinate(x, y) and orientation by the image processing technique. And we compare the real robot's experimental results with the simulation results in the case of a straight line motion, a right turn motion and a left turn motion.

Xanthorrhizol, a natural sesquiterpenoid isolated from the rhizome of Curcuma xanthorrhiza Roxb (Zingiberaceae), has antibacterial activities and protective effects against cisplatin-induced hepatotoxicity. In this study, we investigated the activities of xanthorrhizol as an antioxidant or antiinflammatory agent using neuronal and microglial cells. Xanthorrhizol had potent neuroprotective effects on glutamate-induced neurotoxicity and reactive oxygen species (ROS) generation in the murine hippocampal HT22 cell line. Also, xanthorrhizol inhibited H(2)O(2)-induced lipid peroxidation in rat brain homogenates. The properties of xanthorrhizol as an antiinflammatory agent were investigated in microglial activation by lipopolysaccharide. It reduced the expression of cyclooxygenase-2 and the inducible nitric oxide synthase, which consequently resulted in the reduction of nitric oxide. The production of proinflammatory cytokines, such as interleukin-6 and tumor necrosis factor-alpha in activated microglial cells, was reduced by xanthorrhizol. These results suggest that xanthorrhizol could be an effective candidate for the treatment of Alzheimer's disease- and other neurological disease-related ROS and inflammation.

Numerical methods are developed for calculating the buckling load and obtaining the elastica of tapered column with regular polygon cross-section and both clamped ends, whose material volume and span length are always held constant. The differential equations governing the buckled shape of such column are derived and solved numerically. As the numerical results, the equilibrium paths and the buckling loads are reported. Also the strongest columns by taper type and cross-sectional shape are identified. Introduction Columns have been widely used in various engineering fields since these units are basic structural forms. Estimating the buckling loads of nonprismatic columns, which have the same volume with specific length, is attractive in the viewpoint of optimal design. Since Lagrange(1770-1773) attempted to determine the optimum shape for a column, many researchers including Keller(1960), Barnes(1988), Cox and Overton(1992), and Lee(2000) determined the shape of the strongest column which is defined as the elastic column of a given length and volume which can carry the highest axial load without buckling. Nowhere in the open literature gave the solutions for the class of elastica problems considered herein: the elastica and buckling load of tapered column of regular polygon cross-section with constant volume and constant Professor, Provincial College of Damyang, Damyang, Chonnam 517-800, KOREA 2 Professor, Wonkwang University, Iksan, Junbuk 570-749, KOREA 3 Professor, Taejon University, Taejon 300-716, KOREA 4Graduate Student, Wonkwang University, Iksan, Junbuk 570-749, KOREA

This paper deals with the free vibration of tapered Timoshenko beams. The simultaneous differential equations governing the free vibration of tapered Timoshenko beams are derived by decomposing the deformations of the beam into components as transverse deflection, bending rotation and shear distortion. The governing differential equations are first integrated by the Runge–Kutta method and then solved by the determinant search method, combined with the Regula–Falsi method, to obtain the natural frequencies of the beam along with their corresponding mode shapes. In the numerical examples, the effects of various parameters on the frequencies and mode shapes of the beam are extensively discussed.

This paper deals with dynamic optimal arches, built with a constant volume of arch material, that have the largest fundamental natural frequencies. The cross-section of each arch is a solid regular polygon with its depth varying in a functional fashion. Three shapes of arch (circular, parabolic, and sinusoidal) and three kinds of taper type (linear, parabolic, and sinusoidal) are considered. Differential equations governing free vibrations of such tapered arches are derived, in which the effect of rotatory inertia is included; these equations are numerically solved to calculate the natural frequencies. The numerical results are presented in tables and figures that relate the frequency curves to arch parameters. Typical examples of obtaining the geometry of the dynamic optimal arch are presented. Laboratory scale experiments were conducted to measure the natural frequencies.

The effect of light scattering TiO2 particles surface-modified by Al2O3 coating on the characteristics of a dye-sensitized solar cell (DSSC) has been studied in this paper. The surface of the light scattering TiO2 particles was coated with Al2O3 by a modified sol–gel method as a function of the pH and the concentration of colloidal Al2O3. It was revealed that the uniform distribution of Al2O3 nanoparticles leads to an increase in short-circuit photocurrent of the DSSC device, resulting in an increase in energy conversion efficiency. This seems to be due to the increase in light scattering by the combination of the light scattering TiO2 particles and Al2O3 nanoparticles.

Stone-containing urachal cysts are extremely rare in adults. Here, we report the case of a 58-year-old man with a urachal cyst who had lower abdominal pain and urinary frequency. Abdominal ultrasonography and computed tomography showed hyperdense stones in the urachus. He was treated with a laparoscopic excision using a transperitoneal approach. The pathological diagnosis was an inflammed urachal cyst. This rare case illustrates an inflammed urachal cyst containing stones treated with laparoscopy.