An organic hydrogel film with micron-sized pillar array for real-time and indicator-free detection of Zn

A hydrogel sensing film for a real-time and indicator-free detection of Zn²⁺ is developed by embedding a fluorescent indicator 11,16-bis(phenyl)-6,6,21,21-tetramethyl-m-benzi-6,21-porphodimethene in a hydrogel host poly(2-hydroxyethyl methacrylate). The sensing film shows high stability and selectivity to Zn²⁺. The sensitivity of the sensing film is increased by fabricating a micron-sized pillar array on the surface of the sensing film to increase the surface area. For Zn²⁺ concentrations of 10⁻⁴ and 10⁻³ M, the response time is 30 and 3 s, respectively.     

CLTC: a cluster-based topology control for ad hoc networks

The topology of an ad hoc network has a significant impact on its performance in that a dense topology may induce high interference and low capacity, while a sparse topology is vulnerable to link failure and network partitioning. Topology control aims to maintain a topology that optimizes network performance while minimizing energy consumption. Existing topology control algorithms utilize either a purely centralized or a purely distributed approach. A centralized approach, although able to achieve strong connectivity (k-connectivity for k /spl ges/ 2), suffers from scalability problems. In contrast, a distributed approach, although scalable, lacks strong connectivity guarantees. We propose a hybrid topology control framework, cluster-based topology control (CLTC) that achieves both scalability and strong connectivity. By varying the algorithms utilized in each of the three phases of the framework, a variety of optimization objectives and topological properties can be achieved. In this paper, we present the CLTC framework; describe topology control algorithms based on CLTC and prove that k-connectivity is achieved using those algorithms; analyze the message complexity of an implementation of CLTC, namely, CLTC-A, and present simulation studies that evaluate the effectiveness of CLTC-A for a range of networks.     

Determination of retardation parameters of multiple-order wave plate using a phase-sensitive heterodyne ellipsometer

To characterize the linear birefringence of a multiple-order wave plate (MWP), an oblique incidence is one of the methods available. Multiple reflections in the MWP are produced, and oscillations in the phase retardation measurement versus the oblique incident angle are then measured. Therefore, an antireflection coated MWP is required to avoid oscillation of the phase retardation measurement. In this study, we set up a phase-sensitive heterodyne ellipsometer to measure the phase retardations of an uncoated MWP versus the oblique incident angle, which was scanned in the x-z plane and y-z plane independently. Thus, the effect on multiple reflections by the MWP is reduced by means of subtracting the two measured phase retardations from each other. As a result, a highly sensitive and accurate measurement of retardation parameters (RPs), which includes the refractive indices of the extraordinary ray n(e) and ordinary ray n(o), is obtained by this method. On measurement, a sensitivity (n(e),n(o)) of 10(-6) was achieved by this experiment setup. At the same time, the spatial shifting of the P and S waves emerging from the MWP introduced a deviation between experimental results and the theoretical calculation.     

Melatonin Inhibits Osteoclastogenesis and Osteolytic Bone Metastasis: Implications for Osteoporosis

Osteoblasts and osteoclasts are major cellular components in the bone microenvironment and they play a key role in the bone turnover cycle. Many risk factors interfere with this cycle and contribute to bone-wasting diseases that progressively destroy bone and markedly reduce quality of life. Melatonin (N-acetyl-5-methoxy-tryptamine) has demonstrated intriguing therapeutic potential in the bone microenvironment, with reported effects that include the regulation of bone metabolism, acceleration of osteoblastogenesis, inhibition of osteoclastogenesis and the induction of apoptosis in mature osteoclasts, as well as the suppression of osteolytic bone metastasis. This review aims to shed light on molecular and clinical evidence that points to possibilities of melatonin for the treatment of both osteoporosis and osteolytic bone metastasis. It appears that the therapeutic qualities of melatonin supplementation may enable existing antiresorptive osteoporotic drugs to treat osteolytic metastasis.     

Promotion of generation of hydrogen by splitting of water by CNT over Pt/TiO2 catalysts

The generation of hydrogen over CNT/Pt/TiO2 catalysts by the splitting of water under irradiation with UV light is studied. The maximum rate of evolution of hydrogen was 2300 micromolg(-1)h(-1) on 0.06 wt% Pt/TiO2 (sol-gel) and reached a stable value of approximately 2000 micromolg(-1)h(-1) when the Pt loading exceeded at a Pt loading of over 0.06 wt%. Single wall carbon nanotubes (SWCNTs) were applied to enhance the hydrogen generation activity. The evolution rate of hydrogen on 0.06 wt% Pt/0.02 wt% SWCNT-TiO2 (sol-gel) was 3836 micromolh(-1)g(-1). 0.1 M NaCI yielded more hydrogen than any other tested salt. The XRD spectra show that the crystal lattices of commercial TiO2 (ST-21) and self-made TiO2 (sol-gel method) are of the anatase form. However, the TEM images and other catalytic activity data show that the SWCNTs act as wires for the transmission of electrons.     

SrCo1−xSbxO3−δ cathode materials prepared by Pechini method for solid oxide fuel cell applications

In this study, SrCo_1?ySb_yO_3?δ powders were prepared by a modified Pechini method. According to the study results, the cubic Pm3m phase of the SrCo_1?ySb_yO_3?δ ceramics was obtained as 10% of cobalt ions were substituted by antimony ions. Doping of Sb³⁺ ions appeared both to stabilize the Pm3m phase of the SrCo_1?ySb_yO_3?δ ceramics and to enhance densification and retard grain growth. The coefficient of thermal expansion of the SrCo_1?xSb_xO_3?δ ceramics increased with the content of the antimony ions, ranging from 10.17 to 15.37 ppm/°C at temperatures lower than the inflection point (ranging from 450 °C to 550 °C) and from 22.16 to 29.29 ppm/°C at higher temperatures. For the SrCo_0.98Sb_0.02O_3?δ ceramic, electrical conductivity reached a maximum of 507 S/cm at 450 °C. The ohmic and polarization resistances of the single cell with the pure SrCo_0.98Sb_0.02O_3?δ cathode at 700 °C read respectively 0.298 Ω cm² and 0.560 Ω cm². The single cell with the SrCo_0.98Sb_0.02O_3?δ-SDC composite cathode appeared to reduce the impedances with the R₀ and R_P at 700 °C reading respectively 0.109 Ω cm² and 0.127 Ω cm². Without microstructure optimization and measured at 700 °C, the single cells with the pure SrCo_0.98Sb_0.02O_3?δ cathode and the SrCo_0.98Sb_0.02O_3?δ-SDC composite cathode, demonstrated maximum power densities of 0.100 W/cm² and 0.487 W/cm². Apparently, SrCo_1?ySb_yO_3?δ is a potential cathode for use in IT-SOFCs.     

Two-dimensional angle-of-arrival estimation in the presence offinite distance sources

When sources are a finite distance away from an array system, most high-resolution bearing estimation techniques exhibit unsatisfactory performance due to the invalidity of the planar wavefront assumption. This problem has been addressed by a far-field approximation (FFA) method based on a preprocessing scheme. By exploiting favorable characteristics of a uniform linear array, the method constructs a FFA covariance matrix, which is Toeplitz and approximates to the far-field data covariance matrix, from the observed data covariance matrix. Then eigenstructure methods can be applied to perform bearing estimation without revising the planar wavefront assumption. This method is extended to the problem of two-dimensional angle-of-arrival (AOA) estimation using a uniform planar array in the presence of finite distance sources. A procedure is derived for reconstructing the 2-D FFA covariance matrix with block-Toeplitz structure. Using the 2-D FFA covariance matrix, eigenstructure methods can be applied in conjunction with a 2-D AOA search to solve the problem. Simulation results confirm the theoretical work     

Transmission spectral analysis models for the assessment of white-shell eggs and brown-shell eggs freshness

The Journal of Supercomputing - In this study, nondestructive full-spectrum testing was adopted to test the freshness of white-shell eggs and brown-shell eggs. Two hundred and forty each of Lohman...     

Interfacial Reactions of Sn-9Zn-<Emphasis Type="Italic">x</Emphasis>Cu (<Emphasis Type="Italic">x</Emphasis> = 1, 4, 7, 10) Solders with Ni Substrates

This study investigates the effects of various reaction times and Cu contents on the interfacial reactions between Sn-9Zn-xCu alloys and Ni substrates. After aging at 255°C for 1 h to 3 h, the Ni₅Zn₂₁ and Cu₅Zn₈ phases formed at the interface of Sn-9Zn/Ni and Sn-9Zn-1wt.%Cu/Ni couples, respectively. The (Ni,Zn)₃Sn₄ phase was found in the Sn-9Zn-4wt.%Cu/Ni couple, and the (Cu,Ni)₆Sn₅ and Cu₆Sn₅ phases formed, respectively, in the Sn-9Zn-7wt.%Cu/Ni and Sn-9Zn-10wt.%Cu/Ni couples. As the reaction time was increased from 5 h to 24 h, the (Cu₅Zn₈ + Ni₅Zn₂₁) phases replaced the Cu₅Zn₈ phase to form in the Sn-9Zn-1wt.%Cu/Ni couple; the (Ni,Zn)₃Sn₄ phase formed in the Sn-9Zn-4wt.%Cu/Ni couple, and (CuZn + Cu₆Sn₅) formed in the Sn-9Zn-10wt.%Cu alloys. Experimental results indicate that intermetallic compound (IMC) formation in Sn-9Zn-xCu/Ni couples changes dramatically with reaction time and Cu content. The Sn-Zn-Ni, Sn-Cu-Ni, and Sn-Zn-Cu ternary isothermal sections greatly help us to understand the IMC evolutions in the Sn-9Zn-xCu/Ni couples.     

Sr1−xPrxCo0.95Sn0.05O3−δ ceramic as a cathode material for intermediate-temperature solid oxide fuel cells

In this study, the physical properties of the Sr_1−xPr_xCo_0.95Sn_0.05O_3−δ ceramics were measured and their potential for use as a cathode material of intermediate-temperature solid oxide fuel cells (IT-SOFCs) was evaluated. A cubic phase was retained in all of the Sr_1−xPr_xCo_0.95Sn_0.05O_3−δ ceramics. Analysis of the temperature-dependent conductivity found the SrCo_0.95Sn_0.05O_3−δ and Sr_0.9Pr_0.1Co_0.95Sn_0.05O_3−δ ceramics exhibiting semiconductor-like behavior below 550 °C and metal-like behavior above the same temperature. The Sr_0.8Pr_0.2Co_0.95Sn_0.05O_3−δ and Sr_0.7Pr_0.3Co_0.95Sn_0.05O_3−δ ceramics, however, reported a metal-like conductivity in the whole temperature range. The electrical conductivities of the Sr_0.8Pr_0.2Co_0.95Sn_0.05O_3−δ ceramic at 500 °C and 700 °C read respectively 1250 S/cm and 680 S/cm, both of which were superior than those in most of the common perovskites. Single cells with a structure of NiO–Sm_0.2Ce_0.8O_2−δ (SDC)/SDC/Sr_0.8Pr_0.2Co_0.95Sn_0.05O_3−δ-SDC were built and characterized. Addition of SDC in Sr_0.8Pr_0.2Co_0.95Sn_0.05O_3−δ emerged to be a crucial factor reducing the ohmic resistance (R₀) and polarization resistance (R_P) of the cell by facilitating a better adhesion to and electrical contact with the electrolyte layer. The R₀ and R_P of the cell read respectively 0.068 Ω cm² and 0.0571 Ω cm² at 700 °C and 0.298 Ω cm² and 1.310 Ω cm² at 550 °C. With no microstructure optimization and hermetic sealing of the cells, maximum power density (MPD) and open circuit voltage (OCV) reached respectively 0.872 W/cm² and 0.77 V at 700 °C and 0.482 W/cm² and 0.86 V at 550 °C. It is evident that Sr_1−xPr_xCo_0.95Sn_0.05O_3−δ is a promising cathode material for IT-SOFCs.