A new ionic liquids‐based monolithic column for determination of caffeine and theophylline

The present study has concentrated on finding a new stationary phase in liquid chromatography. To improve the selectivity of monolithic column, a new ionic liquids–based (ILs‐based) monolithic column (150 × 4.6 mm i.d.) is synthesized. Characteristic and evaluation of monolithic column are investigated by field emission‐scanning electron microscopy (FE‐SEM) and determination of caffeine and theophylline in high performance liquid chromatography (HPLC). FE‐SEM images show that this monolithic column has a porosity structure. At the condition of mobile phase was 0.06 mol L^?1 Na₂HPO₄ (pH 9.0) and flow rate was 0.7 mL min^?1, a good linear relationship was demonstrated when the concentrations of caffeine and theophylline were in the range of 0.1–60.0 μg mL^?1. These two compounds can obtain better resolution on the ILs‐based monolithic column than non‐ILs monolithic column, and the recoveries ranged from 97.40% to 108.00% and the interday and intraday relative standard deviations were less than 5%. The HPLC method, developed in this study, was proved to be acceptable for drugs assay, and this ILs‐based monolithic column as the stationary phase was a potential tool for future HPLC separation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Characteristics of Y3Al5O12:Ce phosphor powders prepared by spray pyrolysis from ethylenediaminetetraacetic acid solution

Nanometer and submicron-sized YAG:Ce phosphor powders were prepared by spray pyrolysis from the spray solutions with ethylenediaminetetraacetic acid (EDTA). The precursor powders with hollow and thin wall structure turned to the fine-sized YAG:Ce phosphor powders after post-treatment at high temperatures of 1400 and 1500 °C. The mean size of the phosphor powders post-treated at a temperature of 1500 °C was 0.72 μm. The white LEDs formed from the YAG:Ce phosphor powders post-treated at 1400 and 1500 °C showed (0.2781, 0.2871) and (0.2731, 0.2795) on the CIE chromaticity diagram, and about 78.20 and 79.04 of Ra. The luminous efficiency of the white LED formed from the commercial YAG:Ce phosphor powders was 84.36 lm/W. However, the luminous efficiencies of the white LEDs formed from the YAG:Ce phosphor powders post-treated at 1400 and 1500 °C were 47.74 and 76.64 lm/W.     

Activated carbon nanofiber produced from electrospun polyacrylonitrile nanofiber as a highly efficient formaldehyde adsorbent

Electrospun polyacrylonitrile (PAN)-based nanofiber with a uniform diameter of ca. 800 nm was carbonized and steam-activated to produce activated carbon nanofiber with tailored microporosity and abundant nitrogen-containing functional groups as highly efficient adsorption sites. A remarkable amount of formaldehyde, a typical indoor pollutant, was adsorbed onto the pore surface of the PAN-based activated carbon nanofibers even at a low concentration (ca. 11 ppm), demonstrating more than twice as long as breakthrough time of formaldehyde adsorption as compared to conventional activated carbon fibers of larger fiber diameter. The tailored shallow microporosity was considered to afford the preferential adsorption of formaldehyde also in a humid environment.     

Synthesis and structural characterization of the novel unusual oxido-bridged rhenium complex with Re atoms in two different coordination environments

A new binuclear mixed-valence complex [ReCl₄(py)(μ-O)Re(py)₄Cl]·2py was obtained by solvothermal synthesis in a Berghoff autoclave. It has been studied by IR, reflectance spectra, TGA and X-ray measurements, which support the assumption, that two Re centres with different coordination environments are present. Most plausible, yet not unambiguous oxidation state assignment is Re^III/IV.     

Influence of Palladium Thickness on the Soldering Reactions Between Sn-3Ag-0.5Cu and Au/Pd(P)/Ni(P) Surface Finish

This study provides a comparison of the influence of Pd(P) thickness on reactions during soldering with the Sn-3Ag-0.5Cu alloy. Soldering was carried out in an infrared-enhanced conventional reflow oven, and a multiple reflow test method (up to ten cycles) was performed. With increasing Pd(P) thickness, the (Cu,Ni)₆Sn₅ grew more slowly at the solder/Ni(P) interface, while the Ni₂SnP/Ni₃P bilayer became predominant after the first reflow. These three intermetallics, i.e., (Cu,Ni)₆Sn₅, Ni₂SnP, and Ni₃P, gradually coarsened as the number of reflow cycles increased. Furthermore, an additional (Ni,Cu)₃Sn₄ layer appeared between (Cu,Ni)₆Sn₅ and Ni₂SnP, especially for the case of a thicker Pd(P) layer (0.2 μm). The attachment of the (Ni,Cu)₃Sn₄ to the Ni₂SnP, however, was fairly poor, and a series of microcracks formed along the (Ni,Cu)₃Sn₄/Ni₂SnP interface. To quantify the mechanical response of the interfacial microstructures, shear testing was conducted at two different shear speeds (0.0007 m/s and 2 m/s). The results indicated that the interfacial strength and the Pd(P) thickness were strongly correlated.     

Aerobiology of a high-line speed cattle abattoir

The operation of the high-line speed cattle abattoir studied follows a plant-created hazard analysis and critical control point (HACCP) plan that is recognized by the Canadian Food Inspection Agency. Measurement of bioaerosols is not a part of this plan. In this study CFUs in air of selected abattoir processes were enumerated after impinging air onto tryptic soy agar plates with a slit air sampler for 10 to 20 min. The total viable count (TVC) per liter of air was calculated for each sample following incubation at 30 degrees C for 24 h. Monthly samples were collected on the hide removal floor and the carcass dressing floor from March 1998 to April 1999. Mud tag, dirt, and wetness of incoming hides were scored subjectively on the hide removal floor. The other processes were sampled in 3 separate months. The TVC at two locations on the hide removal floor (center of hide removal floor [CHF] and top of hide puller [THP]) had a strong association to each other (r = 0.84; P < 0.001). The mean TVC at the CHF and THP was 10.0 and 11.5, respectively, and the TVC for individual samples ranged from 2 to 42 at these locations. The TVC means for all the other processes ranged from 0.01 to 0.7. Tag and TVC on the hide removal floor had a different seasonal distribution with TVC being highest in the warm months (April to October 1998) and lowest for November to April 1999. No significant relations between TVC and the dirt and wetness variables were evident for the CHF and THP locations on the hide removal floor. It was concluded that the control of aerosols in the hide removal floor should be treated as a critical control point in the HACCP plan.     

Electrical properties of colloidal polyaniline‐2‐naphthalene sulfonic acid/graphene nanoparticle composite films

Polyaniline (PANI) nanocomposites containing different weight percentages of graphene (GR) are chemically prepared in the presence of β‐naphthalene sulfonic acid (NSA) and characterized using attenuated total reflectance Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction. The characterization results suggest that the composites are formed via the interconnected fibrillar structure forming the semi‐crystalline/amorphous configuration by the β‐napthalene sulfonic acid (β‐NSA). The conductivities of the composites suggest that the composites undergo by two different regions of I and II before and after 378 K. The electrical conductivity of the composites is increased by increasing temperature. The dependence of conductivity on temperature implies that the PANI‐NSA/GR composites are organic semiconductors. POLYM. COMPOS., 35:60–67, 2014. © 2013 Society of Plastics Engineers     

An efficient one-step lookahead A* algorithm for PM-CT scheduling problems

In this paper, we present an improved one-step lookahead A* algorithm for the scheduling problem for parallel-mode cluster tools, where n wafer types are simultaneously processed on a cluster tool with m chambers. Specifically, we suggest a refined cost function, priority-based node selection, N-chamber cycle detection to identify deadlock situations, and a one-step lookahead method to reduce the number of unsafe states generated. Using numerical experiments, we show that the proposed algorithm leads to a significant reduction in the number of explored states and execution time necessary to find an optimal solution.