201   W(CO)6-Catalyzed Oxidative Carbonylation of Primary Amines to N,N prime -Disubstituted Ureas in Single or Biphasic Solvent Systems. Optimization and Functional Group Compatibility Studies W(CO)6-Catalyzed Oxidative Carbonylation of Primary Amines to N,N prime -Disubstituted Ureas in Single or Biphasic Solvent Systems. Optimization and Functional Group Compatibility Studies    2000 Primary amines undergo carbonylation to N,N prime -disubstituted ureas using W(CO)6 as the catalyst, I2 as the oxidant, and CO as the carbonyl source. Preparation of various N,N prime -disubstituted ureas from aliphatic primary amines, RNH2 (R = n-Pr, n-Bu, i-Pr, sec-Bu, or t-Bu), was achieved in good to excellent yields. Studies of functional group compatibility using a series of substituted benzylamines demonstrated broad tolerance of functionality during the carbonylation reaction. Preparatio... 查看全文

202   Properties of Fe3B/(Pr, Tb)2Fe14B bulk nanocomposite magnets prepared by spark plasma sintering Properties of Fe3B/(Pr, Tb)2Fe14B bulk nanocomposite magnets prepared by spark plasma sintering    2007 Amorphous melt-spun ribbons of Pr4.2Tb0.3Fe78B17.5 alloy were consolidated into bulk nanocomposite magnets by Spark Plasma Sintering method. Effect of sintering conditions on the density, microstructure and magnetic properties were studied. Higher sintering temperature improved the densification of the magnets, while deteriorated their magnetic properties simultaneously due to the excess crystal grain growth. Magnet possessed a Br of 1.04 T and a JHc of 220 kA/m under the optimal sintering condi... 查看全文

203   Electron Propagator Theory of Guanine and Its Cations:  Tautomerism and Photoelectron Spectra Electron Propagator Theory of Guanine and Its Cations:  Tautomerism and Photoelectron Spectra O. Dolgounitcheva, V. G. Zakrzewski, and J. V. Ortiz*    2000 Electron propagator methods are applied to the ionization energies of the five most stable tautomers of guanine. Excellent agreement with gas-phase photoelectron spectra is obtained for the amino-oxo form. of 7H-guanine. According to ionization energy assignments, both 9H-guanine and its amino-oxy tautomers also may be present in the gas phase. The presence of amino-oxy 7H-guanine, however, is less certain, due to its higher total energy. In all cases, the lowest ionization occurs from a π leve... 查看全文

204   Do Insulin-treated Diabetic Patients Use an Injection-meal-interval in Daily Life? Do Insulin-treated Diabetic Patients Use an Injection-meal-interval in Daily Life? G. M. Reaven    2009 查看全文

205   Effect of WO3 and MoO3 addition on LnTiTaO6 (Ln = Ce, Pr and Nd) microwave ceramics Effect of WO3 and MoO3 addition on LnTiTaO6 (Ln = Ce, Pr and Nd) microwave ceramics    2009 The effect of dopants such as WO3 and MoO3 on the structural, processing and microwave dielectric properties of LnTiTaO6 (Ln = Ce, Pr and Nd) ceramics is reported. Conventional solid-state ceramic route was used for the preparation of samples. The samples are calcined and sintered at optimized temperatures. A reduction of 50 °C in the sintering temperature was observed for all the samples. The crystal structure of the materials was analyzed using X-ray diffraction techniques and the surface ... 查看全文

206   Microstructure and magnetic properties of rapid quenching (Nd,Pr)10.5Fe81.5-x ZrxCo2B6 alloys by Zr substitution Microstructure and magnetic properties of rapid quenching (Nd,Pr)10.5Fe81.5-x ZrxCo2B6 alloys by Zr substitution    2005 The effects of substitution of Fe by Zr on the microstructure and magnetic properties of (Nd,Pr)10.5Fe81.5-x ZrxCo2B6 alloys which were prepared by overquenching and post annealing method were investigated. The free surface microstructures of crystallized ribbons were observed by means of atom force microscopy (AFM). The addition of Zr dopant will significantly reduce the average grain size of ribbons, from -150 nm of Zr-free (Nd,Pr)10.5Fe81.5Co2B6 alloy to -60 nm of (Nd,Pr)10.5Fe80.5 Zr1Co2B6 a... 查看全文

207   Highly efficient electron-transfer processes over thermally activated alkaline earth oxides. Monolayer anion radical formation with nitrobenzene-magnesium oxide and high concentrations of carbon monox Highly efficient electron-transfer processes over thermally activated alkaline earth oxides. Monolayer anion radical formation with nitrobenzene-magnesium oxide and high concentrations of carbon monox K. J. Klabunde, R. A. Kaba, R. Morris    1978 查看全文

208   Use of Concentrated Alkali and Acid to Achieve Changes in pH Use of Concentrated Alkali and Acid to Achieve Changes in pH    2009 查看全文

209   Divinylphenylene-bridged diruthenium complexes bearing Ru(CO)CI(P iPr3)2 entities Divinylphenylene-bridged diruthenium complexes bearing Ru(CO)CI(P iPr3)2 entities    2006 The divinylphenylene-bridged diruthenium complexes (E,E)-[{(P iPr3)2(CO)ClRu}2(μ-HC=CHC 6H4CH=CH-1,3)] (m-2) and (E,E)-[{(PiPr 3)2(CO)ClRu}2(μ-HC=CHC6H 4CH=CH-1,4)] (p-2) have been prepared and compared to their PPh 3-containing analogues m-1 and p-1. The higher electron density at the metal atoms increases the contribution of the metal end groups to the bridge-dominated occupied frontier orbitals and stabilizes the various oxidized forms with respect to those of m-1 and p-1. This has been... 查看全文

210   Growth and transport features of electron-doped superconductor Pr 1-xLaCexCuO4 - δ thin films Growth and transport features of electron-doped superconductor Pr 1-xLaCexCuO4 - δ thin films    2009 T″-phase electron-doped superconductor Pr1-xLaCe xCuO4-δ (PLCCO) thin films are successfully prepared on SrTiO3 (100) substrates by using the dc magnetron sputtering method. It is found that the films each have a highly oriented structure along the c-axis. For optimally doped films with x 0.10, the superconducting transition temperature Tc is 23.5 K, which is similar to that of a single crystal. The quadratic temperature dependence of the resistivity is observed when T > Tc, which... 查看全文

211   P15.02: First embryonic movements are executed rhythmically P15.02: First embryonic movements are executed rhythmically Elizabeth A. Wilson-Ormond, Matthew S. Ellis, Eric N. Powell, Yungkul Kim and Shu-I Li    2010 查看全文

212   Evidence for a nodeless gap from the superfluid density of optimally doped Pr1.855Ce0.145CuO4-y films Evidence for a nodeless gap from the superfluid density of optimally doped Pr1.855Ce0.145CuO4-y films    2002 The ab-plane superfluid density in optimally doped Pr1.855Ce0.145CuO4-y films was analysed. The films were prepared by molecular beam epitaxy on SrTiO3 substrates. Results showed that superfluid density at low temperature is well fitted by an exponential temperature dependence which is consistent with a nodeless gap and is incompatible with d-wave superconductivity. 查看全文

213   Optimization of protein recovery during hydrolysis of yellowfin tuna (Thunnus albacares) visceral proteins Optimization of protein recovery during hydrolysis of yellowfin tuna (Thunnus albacares) visceral proteins    2011 Protein hydrolysates were prepared from yellowfin tuna viscera using Alcalase®. Response surface methodology (RSM) was applied to study the effect of independent variables, enzyme activity, temperature, and time on the protein recovery (PR) as the response. The coefficient of determination (r2 = 98%) was satisfactory, and the lack of fit test showed a non-significant value for the PR model equation, indicating that the regression equation was adequate for predicting the PR under tested combin... 查看全文

214   Experimental use of TRMM precipitation radar observations in 1D+4D-Var assimilation Experimental use of TRMM precipitation radar observations in 1D+4D-Var assimilation    2005 This paper presents a new application of the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) observations for indirect assimilation into the European Centre for Medium-Range Weather Forecasts (ECMWF) model. The PR reflectivities are first processed using a one-dimensional variational (1D-Var) method to adjust model temperature and specific humidity. The retrieved Total Column Water vapour (TCWV) is then assimilated into the operational four-dimensional variational (4D-Var) sy... 查看全文

215   Microstructures, mechanical properties and corrosion behavior. of high-pressure die-cast Mg-4Al-0.4Mn-xPr (x = 1, 2, 4, 6) alloys Microstructures, mechanical properties and corrosion behavior. of high-pressure die-cast Mg-4Al-0.4Mn-xPr (x = 1, 2, 4, 6) alloys    2009 Mg-4Al-0.4Mn-xPr (x = 1, 2, 4 and 6 wt.%) magnesium alloys were prepared successfully by the high-pressure die-casting technique. The microstructures, mechanical properties, corrosion behavior. as well as strengthening mechanism were investigated. The die-cast alloys were mainly composed of small equiaxed dendrites and the matrix. The fine rigid skin region was related to the high cooling rate and the aggregation of alloying elements, such as Pr. With the Pr content increasing, the α-Mg gr... 查看全文

216   Methodological Approaches Methodological Approaches Alberto Garrido, M. Ramón Llamas, Consuelo Varela-Ortega, Paula Novo, Roberto Rodríguez-Casado;Maite    0 The purpose of this chapter is to describe the methodologies applied in this study and to discuss other methods that are also applied in virtual-water studies. Within the virtual-water literature, the general approach is based on calculations of the virtual-water content of products in order to estimate the water footprint (WF) of a sector or economy. However, the examples found in the literature show certain differences with respect to the general approach (Hoek... 查看全文

217   Microstructures and mechanical properties of high-pressure die-cast Mg-4Al-0.4Mn-xPr alloys Microstructures and mechanical properties of high-pressure die-cast Mg-4Al-0.4Mn-xPr alloys    2009 Mg-4Al-0.4Mn-xPr (x=0, 1, 2, 4 and 6, mass fraction, %) magnesium alloys were prepared by high-pressure die-casting technique. The effect of Pr on the microstructures and mechanical properties of die-cast Mg-4Al based alloy were investigated by XRD, FESEM, microhardness test, tensile and compressive properties tests and analysis of fracture surface. The results show that the fine rigid skin region is related to the aggregation of Pr and fine microstructure. Al2Pr and Al11Pr3 phases are mainly co... 查看全文

218   Electrodeposition and characterization of rare-earth element filled thermoelectric material CoSb3Smx and CoSb3Prx Electrodeposition and characterization of rare-earth element filled thermoelectric material CoSb3Smx and CoSb3Prx    2010 Sm, Pr-filled Skutterudite was prepared by electrodeposition in ionic liquid at the room temperature. The optimum processing conditions for preparing Skutterudite filled with a variety of rare-earth elements, were investigated. Methods of equipment analysis, such as scanning electron microscopy, energy dispersive spectrometer, and X-ray diffraction, were employed to characterize the morphologies, the compositions, and the crystal structure of the above Skutterudites. Under the optimized reaction... 查看全文

219   The Conventional Method of the Determination of Enthalpy Change at Ion Solvation in Solutions:  Is It Correct? The Conventional Method of the Determination of Enthalpy Change at Ion Solvation in Solutions:  Is It Correct? N. B. Zolotoy* and G. V. Karpov    2000 It is shown that the conventional (using the Born?Haber cycle) method of the determination of enthalpy change at ion solvation in solutions gives incorrect values for this fundamental parameter. A new experimental method free from the defects of the conventional one is presented. 查看全文

220   The Order of Accuracy of Quadrature Formulae for Periodic Functions The Order of Accuracy of Quadrature Formulae for Periodic Functions Alex;er Kurganov;Jeffrey Rauch    0 The trapezoidal quadrature rule on a uniform. grid has spectral accuracy when integrating C ∞ periodic function over a period. The same holds for quadrature formulae based on piecewise polynomial interpolations. In this paper, we prove that these quadratures applied to Wperr,p{\rm{W}}_{{\rm{per}}}^{{\rm{r,p}}} periodic functions with r > 2 and p ≥ 1 have error O((Dx)r){\mathcal O}((\Delta x)^r) . The order is in... 查看全文

221   Flame spray pyrolysis for preparing red-light-emitting, submicron-sized luminescent strontium titanate particles Flame spray pyrolysis for preparing red-light-emitting, submicron-sized luminescent strontium titanate particles    2006 SrTiO3:Pr3+,Al3+ red-light-emitting phosphor particles were directly prepared by flame spray pyrolysis without any post-heat treatments. The morphology, crystallinity and photoluminescence (PL) of the as-prepared SrTiO3:Pr3+,Al3+ particles were systematically investigated. The as-prepared particles showed good morphological characteristics and a high crystallinity. The geometric mean diameters of the particles ranged from 0.53 to 0.70 μm. The particles showed a bright red emission at 615 nm f... 查看全文

222   Texture and magnetic properties of nanocomposite Pr2Fe14B/α-Fe melt-spun ribbons Texture and magnetic properties of nanocomposite Pr2Fe14B/α-Fe melt-spun ribbons    2007 The effect of quenching rate on texture formation and magnetic properties of nanocomposite Pr2Fe14B/α-Fe melt-spun ribbons has been investigated. The c-axis texture of Pr2Fe14B phase perpendicular to the. ribbon plane was found on free surface of melt-spun ribbons prepared by optimized melt-spun technique. The formation of c-axis texture mainly result from the crystallites of Pr2Fe14B growing up along the flow of heat, which is induced by the contact of melt alloy with the surface of Cu wh... 查看全文

223   Platinum precursors effects on Pt/(Ce-Zr-La-Pr)O catalysts Platinum precursors effects on Pt/(Ce-Zr-La-Pr)O catalysts    2006 (Ce-Zr-La-Pr)O acted as substrates and Pt acted as catalytic active component, the influences of the precursors, H2PtCl6, Pt(NH3)2 (NO2)2 and Pt(OH)2(C2H5 ONH2)2, and their solutions acidities on the catalytic performances and active metal distribution degrees of the catalysts were studied by TPR and CO pulse titration technologies. The results show that: (1) Pt precursors and their solutions pH values influenced the catalytic activities obviously, the oxygen storage capabilities (for short OSCs... 查看全文

224   Microstructure and magnetic properties of (Nd, Pr)10.5(Fe, Zr)83.5-x CoxB6 alloys Microstructure and magnetic properties of (Nd, Pr)10.5(Fe, Zr)83.5-x CoxB6 alloys    2005 Effects of addition of Co on the microstructure and magnetic properties of the series of (Nd, Pr)10.5(Fe, Zr)83.5-xCoxB6 alloys, which were prepared by over-quenching and post annealing method, were investigated. The free surface microstructures of crystallized ribbons were observed by means of Atom force microscopy (AFM). The significant improvement of remanence Br and maximum energy product (BH)m by Co addition is attributed to the increase of each phase magnetization and the exchange-coupling... 查看全文

225   Initial-boundary value problems for first-order hyperbolic equations with involution Initial-boundary value problems for first-order hyperbolic equations with involution M. Sh. Burlutskaya;A. P. Khromov    2011 查看全文

226   Adsorption property of in situ immobilized black wattle tannin to La3+, Pr3+ and Nd3+ Adsorption property of in situ immobilized black wattle tannin to La3+, Pr3+ and Nd3+    2011 A new kind of adsorbent was prepared from the bark of black wattle being rich of tannin; furthermore, the cross-linking reaction of formaldehyde was used to immobilize tannin in situ to get the adsorbent. The adsorption property of this new adsorbent to ions of light rare earth such as La3+, Pr3+ and Nd3+ (RE3+) in aqueous solution was investigated. Results show that the optimum pH value of this adsorbent to La3+ is about 5.0, while the optimum value of Pr3+ and Nd3+ is about 5.5. The equilibriu... 查看全文

227   The microstructure and magnetization behaviors of (Pr8.2Fe 86.1-xCoxB5.7)0.99Zr0.01 (x = 0-10) nanocomposite magnets The microstructure and magnetization behaviors of (Pr8.2Fe 86.1-xCoxB5.7)0.99Zr0.01 (x = 0-10) nanocomposite magnets    2011 Nanocomposite (Pr8.2Fe86.1-xCoxB 5.7)0.99Zr0.01 (x = 0-10) ribbons consisting of Pr2(Fe,Co)14B and -(Fe,Co) phases were prepared by a melt-spun technique. The microstructure and magnetic properties were studied. The results show that the Curie temperature increases drastically with increasing Co content. The optimal permanent magnetic properties are obtained at x 2, and the value of Hci, Ms, Mr, and (BH)max are 6.52 kOe, 150.2 emu/g, 120.9 emu/g, and 22.34 MGOe, respectively. Typical magnetizati... 查看全文

228   Synthesis and low-voltage characteristics of CaTiO3:Pr luminescent powders Synthesis and low-voltage characteristics of CaTiO3:Pr luminescent powders    1996 The perovskite CaTiO3:Pr phosphors which have relatively small bandgaps were synthesized and characterized for their application to field emitter displays. Good crystal powders, homogeneous, small (approx.1 μm), and spherical, were easily formed without flux. Phosphor preparation parameters such as heat-treatment temperature, time, and activator concentration were optimized for the maximal intensity of photoluminescence. Phosphor cathodoluminescent characteristics were examined by a refractor... 查看全文

229   Research on the properties of CaTiO3:Pr3+ long afterglow phosphors prepared by the oxalate-co-precipitation method Research on the properties of CaTiO3:Pr3+ long afterglow phosphors prepared by the oxalate-co-precipitation method    2009 The long red color afterglow phosphors, CaTiO3:Pr3+ synthesized by the oxalate-co-precipitation method at 700-1000°C, are tested by the TG-DSC, XRD, TEM and luminescent of phosphor. The effects of different sintering temperatures on luminescent performance are analyzed. Photoluminescence and decay curves show that the sample obtained at the sintering temperature of 900°C exhibited the optimal luminous property. 查看全文

230   Effect of Ti substitution on magnetic properties and microstructure of nanocomposite melt-spun (Nd, Pr)10.5 Fe81.5-xTixCo2B6 alloys Effect of Ti substitution on magnetic properties and microstructure of nanocomposite melt-spun (Nd, Pr)10.5 Fe81.5-xTixCo2B6 alloys    2012 A series of bonded magnets of (Nd, Pr)10.5 Fe81.5-xTixCo2B6 (x=0.0, 1.0, 2.0, 3.0, 4.0, 5.0) alloys were prepared by a melt-spun method. The effects of Ti substitution on the magnetic properties and microstructure of alloys have been investigated. Ti substitution significantly reduces the average grain size of alloy ribbons. For (Nd, Pr)10.5 Fe78.5Ti3Co2B6 alloy with 3at% Ti, the average grain size on the ribbon free surface is about 70 nm and the grains are homogeneous. For more Ti contents, th... 查看全文

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