Effect of sintering temperature on microstructures and microwave dielectric properties of Ba<Subscript>2</Subscript>MgWO<Subscript>6</Subscript> ceramics

The microwave dielectric properties of Ba₂MgWO₆ ceramics were investigated with a view to the use of such ceramics in mobile communication. Ba₂MgWO₆ ceramics were prepared using the conventional solid-state method with various sintering temperatures. Dielectric constants (? _r ) of 16.8–18.2 and unloaded quality factor (Q _u  × f) of 7000–118,200 GHz were obtained at sintering temperatures in the range 1450–1650 °C for 2 h. A maximum apparent density of 6.76 g/cm³ was obtained for Ba₂MgWO₆ ceramic, sintered at 1650 °C for 2 h. A dielectric constant (? _r ) of 18.4, an unloaded quality factor (Q _u  × f) of 118,200 GHz, and a temperature coefficient of resonant frequency (τ _f ) of ?34 ppm/°C were obtained when Ba₂MgWO₆ ceramics were sintered at 1650 °C for 2 h.     

Algorithm for automatic parting surface extension in the mold design navigating process

This study focused on the planning and development of an algorithm and process for automatic parting surface design under the CAD software architecture. Relating to the smooth opening of a mold, the parting surface is an important step of mold design. The parting surface can be categorized into the main parting surface and the shut-off parting surface. This study developed an algorithm of extension rules for the main parting surface and determined the contour vector and geometric relationship via computer software. It can realize the main parting surface automatic extension and can be embedded into a web-based mold design navigating process. Through a standardized design process, it can reduce the number of mouse clicks by 90%, enabling users to rapidly complete mold designs, reduce design errors, and improve efficiency.     

Cytotoxicity of curcuminoids and some novel compounds from Curcuma zedoaria

Bioassay-directed fractionation of an EtOH extract of Curcuma zedoaria led to isolation of an active curcuminoid, which was identified as demethoxycurcumin (2) by comparison of its 1H and 13C NMR spectra with literature data and by direct comparison with synthetic material. Curcumin (1) and bisdemethoxycurcumin (3) were also obtained. Curcuminoids (1-3) were synthesized and demonstrated to be cytotoxic against human ovarian cancer OVCAR-3 cells. The observed CD50 values of 1, 2, and 3 were 4.4, 3.8, and 3.1 microg/mL, respectively. Three additional novel compounds, 3, 7-dimethylindan-5-carboxylic acid (4), curcolonol (5), and guaidiol (6), were also isolated from the EtOH extract. The structures and relative stereochemistry of 4-6 were determined by spectroscopic methods and X-ray crystallographic analysis.     

Truncating the putative membrane association region circumvents the difficulty of expressing hepatitis C virus protein E1 in Escherichia coli

The putative E1 of hepatitis C virus (HCV) was expressed in Escherichia coli using a glutathione-S-transferase (GST) fusion protein system. The full length E1 protein is difficult to express. A series of E1 DNA fragments was generated and used for expression vector construction. Fusion proteins containing the E1 C-terminal region could not be expressed. When this region was truncated, the fusion proteins were synthesized to high levels. The possibility of this C-terminal region hampering the production of fusion protein was further explored. A construct with this segment directly fused to the C-terminus of GST indeed generated no detectable recombinant protein. According to the predicted structure of E1, this region may have membrane-associating properties. The expression results suggest a general approach to facilitate the production of viral membrane proteins in prokaryotes. Furthermore, these recombinant E1 proteins generated as antigens were used for Western blotting with sera from HCV-infected individuals. It was found that E1 is antigenic during HCV natural infection.     

Kelly-Based Options Trading Strategies on Settlement Date via Supervised Learning Algorithms

Computational Economics - Option is a well-known financial derivative that attracts attention from investors and scholars, due to its flexible investment strategies. In this paper, we sought to...     

Displacement triangular Ag/Pd nanoplate as methanol- tolerant electrocatalyst in oxygen reduction reaction

Porous triangular Ag/Pd nanoplates with different alloy ratios, including Ag₁₈Pd₁, Ag₁₈Pd_1.5, and Ag₁₈Pd₂, were successfully prepared by a galvanic displacement reaction. These alloy nanoplates were then used as methanol-tolerant electrocatalysts in an alkaline oxygen reduction reaction (ORR). Electrochemical measurements were conducted using an ultrathin film rotating ring-disk electrode. The mass activity was found to decrease in the order Ag₁₈Pd₁ > Ag₁₈Pd₂ > Ag₁₈Pd_1.5 > Pt nanoparticles > Pd nanoparticles, similar to an observation made in a past analysis of the nanoplates in an electrolyte of free methanol; this indicates that these nanoplate catalysts are more economical than Pd nanoparticles, and even Pt nanoparticles. Additionally, compared to the reactive direction in the case of Pt and Pd nanoparticles toward methanol oxidation in an ORR electrolyte with methanol, all Ag/Pd nanoplate catalysts experienced cathodic currents, which indicate that ORRs occurred even in the presence of methanol. Despite working in a methanol-tolerant solution, the prepared alloy nanoplates still exhibited high electroactivity.     

Thermal behavior and hydrogen production of methanol steam reforming and autothermal reforming with spiral preheating

The present study aims to investigate the thermal behavior and hydrogen production characteristics from methanol steam reforming (MSR) and autothermal reforming (ATR) under the effects of a Cu-Zn-based catalyst and spiral preheating. Two different reaction temperatures of 250 and 300 °C are taken into account. Meanwhile, the O/C ratio (i.e. the molar ratio between O₂ and methanol) and S/C ratio (i.e. the molar ratio between steam and methanol) are controlled in the ranges of 0-0.5 and 1-2, respectively. The condition of O/C = 0 represents the reaction of MSR. By monitoring the supplied power into the reactor with a fixed gas hourly space velocity (GHSV) of 72,000 h⁻¹, the experimental results indicate that an exothermic reaction from ATR can be attained once the O/C ratio is as high as 0.125. Increasing O/C ratio causes more heat released from the reaction, this results in the decrease in the frequency of supplied power, especially at O/C = 0.5. It is noted that the concentration of CO in the product gas is quite low compared to that of CO₂. An increase in O/C ratio abates the concentration of H₂ from the consumption of per mol methanol; however, the H₂ yield in terms of thermodynamic analysis is increased. On account of the utilization of spiral preheating on the reactants, within the investigated operating conditions the methanol conversion and hydrogen yield were always higher than 95 and 90%, respectively. A comparison suggests that the methanol conversion from ATR of methanol with spiral preheating is superior to those of other studies.     

Effect of electrochemical surface area on electroless copper deposition: Pd nanocubes as new activators

In this study, the electrochemical surface area (ESA) and specific activity are used to obtain a fair comparison of various activators used for electroless copper deposition (ECD). Different sizes (i.e., 27, 48, and 63 nm) of Pd nanocubes (NCs) enclosed by {1 0 0} facets were successfully synthesized for use as new activators. The results of an analysis based on mixed potential theory indicated that the specific activities in terms of deposition current densities for the 27, 48, and 63 nm NCs and 9 nm nanoparticles (NPs) were 0.31, 1.06, 0.93, and 0.13 mA cm^?2_ESA, respectively. From the results of electrochemical quartz crystal microbalance measurements, the specific activities calculated from the mean deposition rates of the 27, 48, and 63 nm NCs and 9 nm NPs were 29.62, 68.72, 54.77, and 9.72 μg cm^?2 s^?1, respectively. A specific activity order of 48 nm NC > 63 nm NC > 27 nm NC > 9 nm NP was obtained. The 48 nm Pd NCs exhibited the maximum activity towards the activation of the ECD bath.     

Well-aligned single-crystalline silicon nanowire hybrid solar cells on glass

Hybrid solar cells are fabricated on the glass substrate using well-aligned single-crystalline Si nanowires (SiNWs) and poly(3-hexylthiophene):[6,6]-phenyl-C₆₁-butyric acid methyl ester (P3HT:PCBM). Their key benefits are discussed. The well-aligned SiNWs are fabricated from Si wafer and transferred onto the glass substrate with the P3HT:PCBM. Such SiNWs provide uninterrupted conduction paths for electron transport, enhance the optical absorption to serve as an interesting candidate of the absorber, and increase the surface area for exciton dissociation. Our investigations show that SiNWs are promising for hybrid organic photovoltaic cells with improved performance by increasing the short-circuit current density from 7.17 to 11.61 mA/cm².