A novel one-dimensional nickel(II) complex with a hydrogen-bond-link

A novel compound [Ni(L)(H₂O)₂]_0.5[Ni(L)(WO₄)₂]_0.5·4H₂O (1) (L=3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0^1.18,0^7.12]docosane) has been structurally and magnetically characterized. The nickel(II) ions are shown to be in distorted octahedral environments with secondary amines of macrocycles in which two trans water molecules and two trans tungstate ions are assembled around each metal center. Two nickel(II) complexes are connected into a one-dimensional chain via hydrogen bonds. The magnetic susceptibility measurement for 1 indicates weak antiferromagnetic interaction (J=−1.01(2) cm⁻¹; H=−JΣS_i·S_i+1) between the S=1 nickel(II) paramagnetic centers.     

Correlation between stress-whitening and fracture toughness in rubber-modified epoxies

Fracture toughness of rubber modified epoxy systems was evaluated in relation to stresswhitening. The epoxy systems consisted of diglycidyl ethers of bisphenol A (DGEBA)-based epoxy resin, 4,4′ diaminodiphenyl sulphone (DDS) as curing agent, and carboxylterminated butadiene-acrylonitrile (CTBN) rubber. It was found that a peak value of fracture toughness occurs at a small amount of rubber content (∼ 4 phr) and closely corresponds to that of stress-whitening size. Other properties such as flexural strength and flexural modulus were also found to display maxima at a similar amount of rubber content. © 1996 John Wiley & Sons, Inc.     

Oxide properties and stress corrosion cracking behaviour for Alloy 600 in leaded caustic solutions at high temperature

The stress corrosion cracking behaviour of Alloy 600 in caustic solutions with and without PbO at 315 °C was investigated by means of slow strain rate tension tests. The characterisation of the oxide that formed on Alloy 600 was derived from transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy. Lead was incorporated into the oxide in a metallic lead state and a lead oxide state, which degraded the passivity and induced PbSCC susceptibility. NiB was used as an inhibitor. It reduced the lead incorporation level in the oxide layer and decreased PbSCC susceptibility.     

Reconfigurable Circularly Polarized Microstrip Antenna on a Slotted Ground

A compact square patch antenna with reconfigurable circular polarization (CP) at 2.4 GHz is proposed. Circular polarization is generated by an arc‐shaped slot on the ground plane. In order to switch the CP orientation, the current flow direction of the patch is reconfigured via the PIN diodes mounted on the slot. As the slot and bias circuit are not placed on the patch side, the proposed antenna radiates a CP wave without alteration in the main beam direction. From the experimental results, the impedance and CP bandwidths of the proposed antenna have been demonstrated for up to 80 MHz and 25 MHz, respectively.     

RFID Tag Antenna Coupled by Shorted Microstrip Line for Metallic Surfaces

This letter presents the design of a small and low‐profile RFID tag antenna in the UHF band that can be mounted on metallic objects. The designed tag antenna, which uses a ceramic material as a substrate, consists of a radiating patch and a microstrip line with two shorting pins for a proximity‐coupled feeding structure. Using this structure, impedance matching can be simply obtained between the antenna and tag chip without a matching network. The fractional impedance bandwidth for S₁₁<3 dB and radiation efficiency are about 1.4% and 56% at 911 MHz, respectively. The read range is approximately from 5 m to 6 m when the tag antenna is mounted on a metallic surface.     

Gen2‐Based Tag Anti‐collision Algorithms Using Chebyshev's Inequality and Adjustable Frame Size

Arbitration of tag collision is a significant issue for fast tag identification in RFID systems. A good tag anti‐collision algorithm can reduce collisions and increase the efficiency of tag identification. EPCglobal Generation‐2 (Gen2) for passive RFID systems uses probabilistic slotted ALOHA with a Q algorithm, which is a kind of dynamic framed slotted ALOHA (DFSA), as the tag anti‐collision algorithm. In this paper, we analyze the performance of the Q algorithm used in Gen2, and analyze the methods for estimating the number of slots and tags for DFSA. To increase the efficiency of tag identification, we propose new tag anti‐collision algorithms, namely, Chebyshev's inequality, fixed adjustable framed Q, adaptive adjustable framed Q, and hybrid Q. The simulation results show that all the proposed algorithms outperform the conventional Q algorithm used in Gen2. Of all the proposed algorithms, AAFQ provides the best performance in terms of identification time and collision ratio and maximizes throughput and system efficiency. However, there is a tradeoff of complexity and performance between the CHI and AAFQ algorithms.     

Characterization of an inclusion complex of, 7-dehydrocholesterol and cyclodextrin

7-Dehydrocholesterol (7-DHC) plays an important role in the biosynthesis of vitamin D. It is virtually insoluble in water, in which its manipulation is difficult, but the problems may be alleviated by cyclodextrin inclusion. Cyclodextrins are known to form inclusion complex with many kinds of hydrophobic compounds because their molecular structure generates a hydrophilic exterior surface and a hydrophobic cavity interior. The purpose of this study was to characterize inclusion complex of 7-dehydrocholesterol with cyclodextrin (hydroxypropyl-β-cyclodextrin, HPβCD). The inclusion complex showed good solubility in contrast to physical mixture. The inclusion efficiency determined by HPLC analysis was 83.72%. Additionally, the inclusion complex was characterized by UV–vis spectrophotometry, Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). These results demonstrated that 7-dehydrocholesterol with hydroxypropyl-β-cyclodextrin formed an inclusion complex.     

Antioxidant and anticytokine effects of bovine colostrum in intestinal ischemia/reperfusion injured rat model

The objective of this study was to examine antioxidant and anticytokine effects of bovine colostrum (BC) in an intestinal ischemia/reperfusion injured rat model. Forty Sprague-Dawley rats were induced intestinal ischemia/reperfusion injury. After reperfusion the rats were given BC, 0.9% saline or low fat milk (LFM) orally. The antioxidative activities using superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), catalase (CAT), and malondialdehyde (MDA) were analyzed in this study. Serum cytokine levels [tumor necrosis factor (TNF)-α, interlukin (IL)-1β, IL-6, and IL-10] were also checked. SOD (1.53±0.23 U/mg of protein), GSH-PX (7.62±0.66 U/mg of protein), and CAT (42.16±3.16 U/mg of protein) activities increased and MDA level (0.58±0.05 mmol/mg of protein) decreased significantly in rats fed BC compared to rats fed saline or LFM (p<0.05). TNF-α (7.63±1.31 pg/mL), IL-1β (49.43±4.43 pg/mL), and IL-6 (62.85±7.60 pg/mL) in rats fed BC were significantly lower than saline or LFM (p<0.005), whereas there was no significant difference in IL-10 (220.3±22.06 pg/mL) between experimental groups. In conclusion, BC may have both antioxidative and anticytokine effects in an intestinal ischemia/reperfusion rat model.     

Structure,nonstoichiometry, sintering and oxygen permeability of perovskite SrCo1−2x(Fe,Nb)xO3−δ (x = 0.05, 0.10) oxides

The novel Fe/Nb co-substituted SrCo_1?2x(Fe,Nb)_xO_3?δ (x = 0.05, 0.10) oxides have been synthesized and characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetry (TG), and scanning electron microscopy (SEM). The XRD and DSC results demonstrate that the structural stability of the Fe/Nb co-substituted samples x = 0.05, 0.10 is improved greatly compared to the sample x = 0.00. The Fe/Nb co-doping in the SrCoO_3?δ oxide results in the improved structural stability of the SrCo_1?2x(Fe,Nb)_xO_3?δ (x = 0.05, 0.10) oxides. The nonstoichiometric and sintering properties were investigated by TG and SEM, and the oxygen permeation fluxes were measured at 800–950 °C for the sample x = 0.10. The improved oxygen permeability of the ceramic SrCo_1?2x(Fe,Nb)_xO_3?δ (x = 0.10) membrane compared to the (Ba_0.5Sr_0.5)(Co_0.8Fe_0.2)O_3?δ and SrCo_0.8Fe_0.2O_3–δ membranes, was observed under an air/He oxygen partial pressure gradient at 800–950 °C.     

Microscopic examination of an Alloy 600/182 weld

A microscopic study was carried out to examine the microstructural and compositional features of an Alloy 600/182 weldment. The grain boundaries of the Alloy 600 base metal consisted of low angle boundaries (4.4%), coincidence site lattice boundaries including twins (46.6%), and random high angle grain boundaries (49.0%). The precipitates in the matrix of Alloy 600 were identified as Cr₇C₃, irrespective of the intergranular and intragranular ones. The microstructure of the Alloy 182 weld metal consisted of cellular dendrites in the grains epitaxially solidified from the heat affected zone, and the Mn concentration increased periodically across the dendritic interfaces. Contrary to the Alloy 600 base metal, most of the grain boundaries of the Alloy 182 weld metal were low angle and random high angle grain boundaries, with a negligible fraction of coincidence site lattice boundaries. Tiny Cr-rich M₂₃C₆ and Nb carbides were distributed on the grain boundaries in the weld metal, and a Cr-depletion zone was formed due to the Cr carbide precipitation. Precipitates of (Nb,Ti)C, Al₂O₃ type and TiO₂ type oxides were found in the Alloy 182 weld metal.