Effects of post-annealing on electrical properties of CuF2·xH2O-doped KNN ceramics for rotary-linear ultrasonic motors

Lead-free (K_0.5Na_0.5)NbO₃ (KNN) ceramics were prepared using a novel sintering aid (CuF₂·xH₂O (x$\approx$2)) to investigate the effects of post-annealing temperature and atmosphere on oxygen vacancies, microstructure, and electrical properties. Post-annealing (K_0.5Na_0.5)NbO₃ +?1.5?mol% CuF₂·xH₂O (KNNCH) ceramics at 800?°C under argon was shown to increase the bulk relative density to 97% through the formation of a homogeneous microstructure with liquid phase. The resulting samples presented the following excellent piezoelectric properties: k_p：34.1% ($\pm \text{2\%}$); k_t：45.3% ($\pm \text{2\%}$); Q_m：3170 ($\pm \text{2\%}$); R_z：8.6?Ω ($\pm \text{3}\text{\%}$); and tan$\delta$：0.1%. Our results clearly demonstrate that annealing under argon can produce oxygen vacancies in ceramics, which has a significant influence on the stability of domain structures of the samples. Piezoelectric motors fabricated using these ceramics achieved a velocity of 4.5?mm/s, vertical velocity of 3.02?·mm/s, and output power of 2.93?mW with a negligible increase in temperature and high stability while driven.     

The immunomodulatory effect of topical cyclosporin A in atopic keratoconjunctivitis

PURPOSE: To perform a detailed examination of the immunomodulatory effects of topical cyclosporin A (CsA) in conjunctival tissue from patients with atopic keratoconjunctivitis (AKC). METHODS: Patients with active AKC were randomly allocated into two groups of four patients. For 3 months one group received 2% CsA drops, and the other group received placebo drops. Superior tarsal conjunctival biopsy specimens were harvested before and after treatment and examined by one- and two-color immunohistochemistry to compare leukocyte counts, HLA-DR+ and IL-2R+ cell counts, HLA-DR positivity of conjunctival epithelial cells, and counts of T cells expressing the cytokines interleukin (IL)-2, IL-3, IL-4, IL-5, and interferon (IFN)-gamma. RESULTS: Posttreatment values were significantly less than pretreatment values for the total number of leukocytes and in the numbers of CD3+ T cells, CD4+ cells, CD8+ cells, CD20+ B cells, neutrophils, and macrophages, and there was a decrease in the CD4-CD8 ratio (P = 0.03) in the CsA group. There was a reduction from before CsA treatment to after CsA-treatment in the numbers of HLA-DR+ and IL-2R+ cells (P = 0.03), but the reduction in the epithelial cell HLA-DR expression did not reach significance. The number of T cells staining for IL-3 and IL-5 was reduced, although not to statistical significance, but there was a significant reduction in the number of T cells expressing IL-2 and IFN-gamma (P = 0.03) after CsA treatment compared with initial values. There were no statistically significant differences between pretreatment and posttreatment values in the placebo group. There was a clinical improvement in the CsA group and a clinical worsening in the placebo group. CONCLUSIONS: The in vitro effects of CsA translate into a reduction in T cells, a normalization of the CD4-CD8 ratio, a decrease in T-cell activation, and a reduction in T-cell cytokine expression, especially IL-2 and IFN-gamma. The decrease in HLA-DR expression may be mediated by the change in IFN-gamma. There were fewer B cells but not fewer plasma cells after CsA and no change in IL-4 expression, suggesting minimal effects on type I hypersensitivity responses. There was no significant reduction in mast cell or eosinophil numbers, but direct effects of topical CsA on their function may play a role in the therapy of ocular allergic disease. These results show that the beneficial effects of topical CsA in AKC are accompanied by important changes in conjunctival immune cell profiles.     

Purification and lipid dependence of the recombinant hyaluronan synthases from Streptococcus pyogenes and Streptococcus equisimilis

The two hyaluronan synthases (HASs) from Streptococcus pyogenes (spHAS) and Streptococcus equisimilis (seHAS) were expressed in Escherichia coli as recombinant proteins containing His6 tails. Both enzymes were expressed as major membrane proteins, accounting for approximately 5-8% of the total membrane protein. Using nickel chelate affinity chromatography, the HASs were purified to homogeneity from n-dodecyl beta-D-maltoside extracts. High levels of HAS activity could be achieved only if the purified enzymes were supplemented with either bovine or E. coli cardiolipin (CL), although bovine CL gave consistently greater activity. Mass spectroscopic analysis revealed that the fatty acid compositions of these two CL preparations did not overlap. The two HAS enzymes showed similar but distinct activation profiles with the 10 other lipids tested. For example, phosphatidic acid and phosphatidylethanolamine stimulated seHAS, but not spHAS. Phosphatidylserine stimulated both enzymes. spHAS appears to be more CL-specific than seHAS, although both purified enzymes still contain endogenous CL that can not easily be removed. Both seHAS and spHAS were inhibited by phosphatidylcholine, sphingomyelin, and sulfatides and were not substantially stimulated by cerebrosides, phosphatidylglycerol, or phosphatidylinositol. With both HASs, CL increased the Km for UDP-GlcUA, but decreased the Km for UDP-GlcNAc and gave an overall stimulation of Vmax. A kinetic characterization of the two membrane-bound and purified HASs is presented in the accompanying paper (Tlapak-Simmons, V. L., Baggenstoss, B. A., Kumari, K., Heldermon, C., and Weigel, P. H. (1999) J. Biol. Chem. 274, 4246-4253). Both purified HASs became inactive after storage for approximately 5 days at 4 degreesC. Both purified enzymes also lost activity over 4-5 days when stored at -80 degreesC in the presence of CL, but reached a level of activity that then slowly decreased over a period of months. Although the purified enzymes stored in the absence of CL at -80 degreesC were much less active, the enzymes retained this same low level of activity for at least 5 weeks. When both spHAS and seHAS were stored without CL at -80 degreesC, even after 2 months, they could be stimulated by the addition of bovine CL to approximately 60% of the initial activity of the freshly purified enzyme.     

Synthesis, characterization and electrostatic dissipating ability of poly(oxyethylene) block polyesteramides

Poly(oxyethylene)diamines were included in the copolymerization of ethylene glycol and dicarboxylic acids, such as terephthalic, adipic and sebacic acid, to produce a series of hydrophilic polyether-ester-amides. With the addition of poly(oxyethylene)diamines (average molecular weight of 2,000) to PET in the amounts of 3.2, 6.6, 12 and 16 wt%, melting points of these polymers dropped accordingly, from 240 °C to around 227 °C, and the electronic resistivity decreased from 1×10¹³ to approximately 8×10⁸ ohm/sq. For comparison, the introduction of hydrophilic PEG-2000 or a low molecular weight diamine, such as triethyleneglycol diamine, has less effect on electronic resistivity. Molecular weight, polymer rigidity and ageing are other factors affecting the surface resistivity. The degree of hydrophilicity was measured by the moisture absorption of the fibers made from these polyether-ester-amides. A weight gain of 0.96% was observed for 12 wt% poly(oxyethylene)diamine modified polyether-ester-amides in comparison with 0.40% for the unmodified polyethylene terephthalate). These results are explained by a mechanism involving moisture absorption on the polymer surface through the formation of hydrogen bonding with amide and-(OCH₂CH₂)-functionalities on the polymer surface.     

A two-user approximation-based transmit beamforming for physical-layer multicasting in mobile cellular downlink systems

Multicast has been known as an efficient transmission technique for group-oriented applications such as multi-party video conferencing, video streaming for paid users, online gaming, and social networking. In this paper, we investigate physical-layer multicasting in mobile cellular downlink systems, where the antennas at base station are employed to transmit common signals to multiple users simultaneously. A central design problem of downlink physical-layer multicasting is the search for the optimal beamforming vector that maximizes the multicast rate. Traditionally, the problem has been formulated as a quadratically constrained quadratic programming problem and shown to be NP-hard in general. In this paper, starting from examining the Karush–Kuhn–Tucker stationary conditions, a new method based on two-user approximation is proposed for the search for the optimal beamforming vector. The method is able to achieve a much higher multicast rate than the existing methods and provides an attractive trade-off between performance and complexity, especially for the case of using a large number of antennas. Using a large number of antennas at base station, also known as the large-scale multiple-input and multiple-output technique, has been regarded widely as one of the most promising technologies to increase system capacity, coverage, and user throughput for future generations of mobile cellular systems.     

Kinetics of thermal destruction of Salmonella in ground chicken containing trans-cinnamaldehyde and carvacrol

We investigated the heat resistance of an eight-strain cocktail of Salmonella serovars in chicken supplemented with trans cinnamaldehyde (0 to 1.0%, wt/wt) and carvacrol (0 to 1.0%, wt/wt). Inoculated meat was packaged in bags that were completely immersed in a circulating water bath and held at 55 to 71°C for predetermined lengths of time. The recovery medium was tryptic soy agar supplemented with 0.6% yeast extract and 1% sodium pyruvate. D-values in chicken, determined by linear regression, were 17.45, 2.89, 0.75, and 0.29 min at 55, 60, 65, and 71°C, respectively (z = 9.02°C). Using a survival model for nonlinear survival curves, D-values in chicken ranged from 13.52 min (D(1), major population) and 51.99 min (D(2), heat-resistant subpopulation) at 55°C to 0.15 min (D(1)) and 1.49 min (D(2)) at 71°C. When the Salmonella cocktail was in chicken supplemented with 0.1 to 1.0% trans-cinnamaldehyde or carvacrol, D-values calculated by both approaches were consistently less at all temperatures. This observation suggests that the addition of natural antimicrobials to chicken renders Salmonella serovars more sensitive to the lethal effect of heat. Thermal death times from this study will be beneficial to the food industry in designing hazard analysis and critical control point plans to effectively eliminate Salmonella contamination in chicken products used in this study.     

Hepatoprotection of silymarin against thioacetamide-induced chronic liver fibrosis

BACKGROUND: Liver fibrosis is chronic liver damage usually caused by alcohol, viruses or other toxins and is characterised by an excessive accumulation of extracellular matrix proteins such as collagen. The aim of this study was to establish an animal model of chronic liver damage and investigate molecular mechanisms of silymarin hepatoprotective effects. RESULTS: Thioacetamide (TAA; 100 mg kg^?1 intraperitoneal (i.p.) injection three times weekly) effectively induced chronic liver fibrosis in male ICR mice. Then 24 ICR mice were randomly divided into four groups: (1) saline (i.p.) + water (gavage); (2) saline (i.p.) + 150 mg kg^?1 silymarin (gavage); (3) 100 mg kg^?1 TAA (i.p.) + water (gavage); (4) 100 mg kg^?1 TAA (i.p.) + 150 mg kg^?1 silymarin (gavage). Eight weeks of TAA treatment resulted in lower body weight, serum cholesterol and triglycerides as well as increased liver size, ALT, AST and LDH values (P < 0.05). These TAA‐induced effects were attenuated by silymarin (P < 0.05); therefore silymarin also ameliorated TAA‐induced liver lesions. Effects of silymarin on TAA‐induced chronic liver damage may be attributed to down‐regulation of hepatic MMP‐2, MMP‐13, TIMP‐1, TIMP‐2, AP‐1, KLF6, TGF‐β1, α‐SMA and COL‐α1. CONCLUSION: A mouse model of chronic liver fibrosis was successfully established by injecting 100 mg kg^?1 TAA three times weekly in male ICR mice. Meanwhile, silymarin showed hepatoprotection against TAA‐induced damage. Copyright © 2011 Society of Chemical Industry     

Antimicrobial Effects of Allyl Isothiocyanate and Modified Atmosphere on Pseduomonas Aeruginosa in Fresh Catfish Fillet under Abuse Temperatures

The effects of allyl isothiocyanate (AIT; 18 and 36 μg/L) in vapor phase, modified atmosphere (MA; 49% CO₂, 0.5% O₂, and 50.5% N₂), and their combinations on the growth behavior of Pseduomonas aeruginosa in fresh catfish fillet at different abuse temperatures (8, 15, and 20 °C) were evaluated in this study. Lag phase, maximum growth rate, and shelf life were used as parameters to analyze the antimicrobial effects. Both gaseous AIT and MA alone inhibited the growth potential of P. aeruginosa effectively, prolonging the shelf life by 1.5 to 3.4 times compared to the control at abuse temperatures between 8 and 20 °C. The synergistic effect was observed at 8 °C, extending the shelf life of fresh catfish by more than 6.5 times (≥ 550 h). In addition, the maximum growth rate decreased with decreasing storage temperature, but it was not significantly influenced by the addition of AIT or MA. Hence, the combination of AIT and MA may be used as an effective antimicrobial system to reduce the microbial risks due to temperature abuse and to improve the shelf life of fresh catfish fillet. The proper combination of AIT and MA may be further optimized for industrial applications.     

The wear of ultrafine WC–Co hard metals

The wear performance of ultrafine-grained tungsten carbide–cobalt (WC–Co) hard metals during three-body abrasion and particle erosion has been evaluated and compared to that of similar conventional coarser grained hard metals. The tungsten carbide grain size varied between 0.5 and 3 μm with cobalt contents ranging from 6 to 15%. Silica particles were used in both forms of testing. Erosion was carried out at 60 ms⁻¹ at an impact angle of 75° and abrasion at a velocity of 0.5 ms⁻¹ and a load of 50 N.

The wear resistance of the ultrafine grades was found to be at least double that of the closest conventional fine grained hard metals. These increases in wear performance are considerably higher than any corresponding increase in hardness which is, at most, 25% and is not achieved at the expense of fracture toughness which is maintained at a similar level to that of conventional fine grained hard metals. The increase in wear resistance coincides with a change in the mechanism of material removal. Sub-micron materials experience ductile deformation and bulk removal of material whilst coarser grades display more localised response with extensive fragmentation of the WC grains.     

Three-dimensional millimeter-wave imaging for concealed weapondetection

Millimeter-wave imaging techniques and systems have been developed at the Pacific Northwest National Laboratory (PNNL), Richland, WA, for the detection of concealed weapons and contraband at airports and other secure locations. These techniques were derived from microwave holography techniques that utilize phase and amplitude information recorded over a two-dimensional aperture to reconstruct a focused image of the target. Millimeter-wave imaging is well suited for the detection of concealed weapons or other contraband carried on personnel since millimeter-waves are nonionizing, readily penetrate common clothing material, and are reflected from the human body and any concealed items. In this paper, a wide-bandwidth three-dimensional holographic microwave imaging technique is described. Practical weapon detection systems for airport or other high-throughput applications require high-speed scanning on the order of 3 to 10 s. To achieve this goal, a prototype imaging system utilizing a 27-33 GHz linear sequentially switched array and a high-speed linear scanner has been developed and tested. This system is described in detail along with numerous imaging results