Catalytic performance of cement clinker supported nickel catalyst in glycerol dry reforming

The paper reports the development of cement clinker-supported nickel （with metal loadings of 5 wt%, 10 wt%, 15 wt% and 20 wt%） catalysts for glycerol dry （CO2） reforming reaction. XRF results showed that CaO constituted 62.0% of cement clinker. The physicochemical characterization of the catalysts revealed 32-folds increment of BET surface area （SBET） with the addition of nickel metal into the cement clinker, which was also corroborated by FESEM images. Significantly, XRD results suggested different types of Ni oxides formation with Ni loading, whilst Ca3SiO5 and Ca2Al0.67Mn0.33FeO5 were the main crystallite species for pure cement clinker. Temperature-programmed reduction analysis yielded three domains of H2 reduction peaks, viz. centered at approximately 750 K referred to as type-Ⅰ peaks, another peaks at 820 K denoted as type-Ⅱ peaks and the highest reduction peaks, type-Ⅲ recorded at above 1000 K. 20 wt% Ni was found to be the best loading with the highest XG and H2 yield, whilst the lowest methanation activity. Syngas with lower H2/CO ratios （0.6 to 1.5） were readily produced from glycerol dry reforming at CO2-to-Glycerol feed ratio （CGR） of unity. Nonetheless, carbon deposit comprised of whisker type （Cv） and graphitic-like type （Cc） species were found to be in majority on 20 wt%Ni/CC catalysts.     

Optimization of Nd:YAG laser welding onto magnesium alloy via Taguchi analysis

The use of an Nd:YAG laser for thin plate magnesium alloy butt welding was optimized using the Taguchi analytical methodology. The welding parameters governing the laser beam in thin plate butt welding were evaluated by measuring of the ultimate tension stress. The effectiveness of the Taguchi method lies in clarifying the factor that dominates complex interactions in laser welding. The factors can be the shielding gas, laser energy, convey speed of workpiece, point at which the laser is focused, pulse frequency, and pulse shape. Furthermore, 18 combinations of these six essential welding parameters were set and Taguchi's method followed exactly. The optimal result was confirmed with a superior ultimate tension stress of 169 MPa, 2.5 times larger to that from original set for laser welding.     

Emissive iridium(III) diimine complexes formed by double cyclometalation of coordinated triphenylphosphite

We report on the synthesis of a new series of iridium(III) complexes functionalized with various diimine chromophores, together with a facially coordinated dicyclometalated phosphite chelate and a monodentate anionic ancillary. This conceptual design presents a novel strategy in obtaining a new class of iridium(III) diimine complexes without employment of traditional nitrogen-containing polyaromatic cyclometalates. Additionally, we discuss the basic charactersistics of the ground and lower-lying excited states involved, as documented by crystal structural, photophysical studies, and density functional theory calculations. Fabrication of the green-emitting organic light-emitting diodes with one such dopant, [Ir(dbbpy)(tpit)NCS] (2b), where dbbpy and tpit represent di-tert-butyl-2,2'-bipyridine and dicyclometalated triphenylphosphite, respectively, was successfully made, attaining a peak external quantum efficiency (η(ext)), a luminance efficiency (η(l)), and a power efficiency (η(p)) of 14.1%, 46.6 cd A(-1), and 39.9 lm W(-1), respectively.     

Analyses of gibberellins by capillary electrophoresis-mass spectrometry combined with solid-phase extraction

A new, simple and rapid capillary electrophoresis-mass spectrometry (CE-MS) method, using a cationic polymer-coated capillary to reverse electroosmotic flow, is proposed and validated for the separation and simultaneous quantification of 11 gibberellins (GAs). Under optimum conditions, a baseline separation of 11 GAs, including GA1, GA3, GA4, GA5, GA6, GA7, GA13, GA19, GA20, GA24 and GA53 was accomplished within 25 min using 70 mM ammonium formate/formic acid buffer (pH 3.8) and 2% (v/v) acetonitrile with -25 kV as the separation voltage. Satisfactory results were obtained in terms of linearity (R2 between 0.984 and 0.995), precision (RSD of migration time below 0.8%) and sensitivity (LOD between 0.31 and 1.02 microM). Furthermore, a novel solid-phase extraction (SPE) procedure was developed for the pre-concentration and purification of GAs using Oasis MAX cartridges. The combination of SPE and CE-MS approach was applied to screen for endogenous GAs present in coconut (Cocos nucifera L.) water sample. To illustrate the applicability of the method, GA1 and GA3 were successfully detected and quantified in coconut water. Finally, the GA1 and GA3 identities were further unequivocally confirmed by CE-tandem MS experiments operating in the multiple reaction monitoring mode.     

Molecular Structures and Magnetic Properties of Strongly Antiferromagnetically Coupled Binuclear Copper(II) Complexes [CU2 REP(μ-X)(Y)2]

The molecular structures of binuclear copper(II) complexes [Cu₂REP(μ-OH)(ClO₄)₂] (4) and [Cu₂REP(μ-Cl)Cl₂] (5), in which REP = deprotonated 2,6-bis(1′-(4′-(2″-pyridyl)-2′-thiabutyl))-4-methylphenol, have been characterized by single-crystal X-ray diffraction. The former crystallizes in the triclinic space group Pl? with a = 10.156(3), b = 12.631(3), c = 25.128(10) Å, α = 92.03(3), β = 96.84(3), γ = 108.02(2),° and Z ? 2. Complex 5 crystallizes in the monoclinic space group C2/c with a = 12.166(2), b = 11.825(2), c = 18.240(4) Å, β = 100.97(2)°, and Z =4. All copper ions are pentacoordinated with ligation to a sulfur, a nitrogen, and the bridging phenolato oxygen of the REP ligand, the exogenous bridge, and a counteranion. The coordination geometry of each copper of the binuclear copper sites is square pyramidal in both 4 and 5. Magnetic susceptibility measurements in the temperature range 6–300 K reveal a strong antiferromagnetic spin exchange in 5 (exchange integral 2J = ?460 cm^?1). A diamagnetic behavior is observed for 4 according to a similar cryomagnetic investigation. The diamagnetism of 4 is further confirmed by measurements of magnetic susceptibility through Evan's method at room temperature. Complex 4 has no EPR signal. The powder EPR spectrum of 5 shows the typical triplet state characteristics with Δm = ±1 transitions at g = 2.15 and a weaker Δm = 2 transition at half field with g = 4.24.     

Fundamental Fraction Knowledge of Preservice Elementary Teachers: A Cross‐National Study in the United States and Taiwan

The purpose of this paper is to show the similarities as well as the differences of fundamental fraction knowledge owned by preservice elementary teachers from the United States (N= 89) and Taiwan (N= 85). To this end, we examined and compared their performance on an instrument including 15 multiple‐choice test items. The items were categorized into four different types of fundamental fraction constructs, including part–whole relationship, quotient, equivalence, and meanings of operations. Each item was embedded in the area, linear, or set model except for the items constructed out of the meaning of operations. Several items were featured with a pictorial illustration. Quantitative analysis showed that U.S. preservice teachers were significantly outperformed by their Taiwanese counterparts overall. The difference between the two groups was statistically significant on 12 of 15 items. Findings suggest that preservice elementary teachers from both countries need to be better prepared in their understanding of the meaning of fraction multiplication or division operations. Findings also suggest that U.S. preservice elementary teachers need to be more knowledgeable in dealing with fraction problems embedded in a linear model. Further research is suggested to study the issues raised from the findings.     

Study of structural and electronic transport properties of Ce-doped LaMnO3

The structural and electronic transport properties of La_1−x Ce _x MnO₃ (x=0.0–1.0) have been studied. All the samples exhibit orthorhombic crystal symmetry and the unit cell volume decreases with Ce doping. They also make a metal-insulator transition (MIT) and transition temperature increases with increase in Ce concentration up to 50% doping. The system La_0.5Ce_0.5MnO₃ also exhibits MIT instead of charge-ordered state as observed in the hole doped systems of the same composition.