Pr3+/Er3+ Codoped Ge-As-Ga-S Glasses as Dual-Wavelength Fiber-optic Amplifiers for 1.31 and 1.55 μm Windows

Fluorescence emissions at both 1.31 and 1.55 μm communication windows were observed from Pr³⁺/Er³⁺ codoped Ge-As-Ga-S glasses with a single wavelength pumping at 986 nm. The lifetime of the Er³⁺:⁴ I _11/2 level decreased as the Pr³⁺ concentration increased, and that of the Pr³⁺:¹ G ₄ level increased as the Er³⁺ concentration increased. Energy transfer from the Er³⁺:⁴ I _11/2 level to the Pr³⁺:¹ G ₄ level was responsible for emission of the 1.31 μm fluorescence from the Pr³⁺:¹ G ₄ level. Ge-As-Ga-S glasses that have been doped with Pr³⁺ and Er³⁺ cations are promising amplifier materials for both 1.31 and 1.55 μm communication windows.     

2-D WO3 decorated with Pd for rapid gasochromic and electrical hydrogen sensing

The ultrathin two-dimensional (2D) nanomaterials display unique properties owing to their ultrahigh specific surface area and strong quantum confinement of electrons in two dimensions. In this work, we fabricated a rapid gasochromic and electrical hydrogen sensing system containing 2D WO₃ and Pd nanoparticles. 2D WO₃ nano-plates (NP) are synthesized using sol–gel method and Pd nanoparticles are coated on WO₃ by green photochemical deposition method. The sensor is fabricated by dispersing the 2D WO₃/Pd composite on filter paper. In presence of hydrogen gas, 2D WO₃/Pd composite produces visible change in color from brown to dark blue. With the fabricated sensor, as low as 0.1% H₂ gas in air at room temperature can be easily detected using electrical sensing scheme whereas for higher concentration from 1 to 100%, eye readable gasochromic scheme can be utilized. The use of 2D WO₃ decreased the response time in great deal compared to WO₃ nanoparticles indicating the advantage of 2D structure in fabricating rapid response H₂ sensors. The proposed method is simple and can be easily employed to large scale fabrication system for commercial applications.     

A rapid method for the simultaneous determination of 25 anti-hypertensive compounds in dietary supplements using ultra-high-pressure liquid chromatography

A novel, stable, simple and specific ultra-performance liquid chromatography method with ultraviolet detection (205 nm) for the simultaneous analysis of 25 anti-hypertensive substances was developed. The method was validated according to the International Conference of Harmonisation guidelines with respect to linearity, accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ) and stability. From the ultra-performance liquid chromatography results, we identified the LOD and LOQ of solid samples to be 0.20–1.00 and 0.60–3.00 μg ml^?1, respectively, while those of liquid samples were 0.30–1.20 and 0.90–3.60 μg ml^?1, respectively. The linearity exceeded 0.9999, and the intra- and inter-day precisions were 0.15–6.48% and 0.28–8.67%, respectively. The intra- and inter-day accuracies were 82.25–111.42% and 80.70–115.64%, respectively, and the stability was lower than 12.9% (relative standard deviation). This method was applied to the monitoring of 97 commercially available dietary supplements obtained in Korea, such as pills, soft capsules, hard capsules, liquids, powders and tablets. The proposed method is accurate, precise and of high quality, and can be used for the routine, reproducible analysis and control of 25 anti-hypertensive substances in various dietary supplements. The work presented herein may help to prevent incidents related to food adulteration and restrict the illegal food market.     

Miniaturized Flexible Electronic Systems with Wireless Power and Near‐Field Communication Capabilities

A class of thin, lightweight, flexible, near‐field communication (NFC) devices with ultraminiaturized format is introduced, and systematic investigations of the mechanics, radio frequency characteristics, and materials aspects associated with their optimized construction are presented. These systems allow advantages in mechanical strength, placement versatility, and minimized interfacial stresses compared to other NFC technologies and wearable electronics. Detailed experimental studies and theoretical modeling of the mechanical and electromagnetic properties of these systems establish understanding of the key design considerations. These concepts can apply to many other types of wireless communication systems including biosensors and electronic implants.     

Low-cost broadband millimetre-wave array antenna using waveguide/microstrip feed network and slot pair

A low-cost broadband millimetre-wave planar 30/spl times/30 array antenna is presented. The antenna is fed by a microstrip feed network in the H-plane to decrease fabrication costs, and a waveguide feed network in the E-plane to reduce the feed line loss. The waveguide and microstrip feed network are coupled through the proposed slot pair. The slots are placed one quarter of a guided-wavelength distance apart, so that the reflected waves from the slots cancel each other. A conductive bar is laid above the slots to increase the coupling, which increases the antenna gain by about 1 dBi. The maximum gain is 30.5 dBi at 41.5 GHz. The measured bandwidth is as broad as 7.1%.     

Eleutheroside E,an active compound from Eleutherococcus senticosus,regulates adipogenesis in 3T3-L1 cells

In this study, we investigated the anti-adipogenic effects of Eleutherococcus senticosus and its active compounds in vitro to examine new functions. We first analyzed the active compounds in E. senticosus growing in Korea using HPLC and found that the concentration of eleutheroside B and E was higher in stems and roots than in other plant parts. There were no significant (p<0.05) differences in eleutheroside concentration between plant ages. Anti-adipogenic effects of E. senticosus on lipid accumulation in 3T3-L1 cells were examined. Extracts of stems and roots more effectively inhibited lipid accumulation in 3T3-L1 cells than extracts of other plant parts. Eleutheroside E was responsible for the pharmacological anti-adipogenic effects via regulation of the mTOR pathway. This is the first report of an anti-adipogenic effect of E. senticosus and the active compound eleutheroside E.     

Sample sizes required to detect interactions between two binary fixed-effects in a mixed-effects linear regression model

Mixed-effects linear regression models have become more widely used for analysis of repeatedly measured outcomes in clinical trials over the past decade. There are formulae and tables for estimating sample sizes required to detect the main effects of treatment and the treatment by time interactions for those models. A formula is proposed to estimate the sample size required to detect an interaction between two binary variables in a factorial design with repeated measures of a continuous outcome. The formula is based, in part, on the fact that the variance of an interaction is fourfold that of the main effect. A simulation study examines the statistical power associated with the resulting sample sizes in a mixed-effects linear regression model with a random intercept. The simulation varies the magnitude (Δ) of the standardized main effects and interactions, the intraclass correlation coefficient (ρ), and the number (k) of repeated measures within-subject. The results of the simulation study verify that the sample size required to detect a 2×2 interaction in a mixed-effects linear regression model is fourfold that to detect a main effect of the same magnitude.     

Construction application of Fibre/Mesh method for protecting concrete columns in fire

In this paper, a construction application of a technique to improve the fire resistance of high strength concrete is presented. Before the construction application, fire tests of three hours duration were carried out in accordance with ISO-834. Three types of mitigating methods, namely, a specimen with no protection (control), with fireproof panel protection and with the combination of polypropylene fibre reinforcement and metal mesh confinement (Fibre/Mesh), were applied to full sized columns for comparison purposes. The fire resistance performance of all columns was tested under loads. After the fire tests, the severity of spalling of specimens was assessed, and the best performing technique, Fibre/Mesh, for spalling protection was selected for an application in practice. The process of the construction application is described in detail, including pumping, pouring and compacting of the concrete. The concrete quality was examined and the behaviour of the concrete was observed. Consequently, it was verified that this new spalling resistance technique is feasible in practice.     

Hybrid DSO-GA-based sensorless optimal control strategy for wind turbine generators

The operation of a wind turbine generator involves natural uncertainty due to aerodynamic characteristics, resulting in a system that performs inefficiently. In general, the conventional controller now in wide use is not suitable for every operating point, because its tuning parameters and set-points do not meet the varying system characteristics. A study into an optimal control technique is conducted to reduce the negative effects of inherent uncertainty in system operation. In order to resolve the uncertainty problem, an optimal control method for an effective wind turbine generator is designed on the basis of a sensorless frame by utilizing a hybrid of the direct search optimization method (DSO) and the genetic algorithm (GA). This method is easy to implement and computation of functional derivatives is not necessary. The conventional GA is well known for its high performance in global optimization and its effectiveness in making ideal choices for control variables. The proposed DSO-GA hybrid differs from the conventional GA in terms of the sampling survey and the crossover operation. Moreover, the proposed multivariable optimal control strategy is a sensorless optimization technique that determines the pitch angle of the blades and the yaw angle of the nacelles to produce stable maximum power from a wind turbine system under steady-state operation. The proposed DSO-GA controller is implemented for a lab-scale wind turbine generator exposed to artificial wind, and the experimental results constitute a 3-D performance surface model of output voltage, which is used as an objective function for simulation. The optimization procedure with the objective function is carried out by means of the conventional and proposed methods, whose results reveal that the proposed DSO-GA optimizer yields far better performance in terms of generation number, convergence rate, and robustness. Both techniques are applied to a wind power generator through simulation and experiments. The performances are compared, and conclusions are drawn for each case.