A Necessary Condition of the Cardinal

In this paper the auther begins with some known results about η_λ(=the least cardinal K such that K→(λ)~<∞), proving this theorem: If λ is not Ramsey cardinal and η_λ exists, then for every a<η_λ there is a weakly compact cardinal γ, such that λ<γ_α<η_λandγ_α<γ_βwhenever a<β<η_λ, therefore η_λ is the limit of the sequence(γ_α:a<η_λ), i.e. η_λ=limγ_α. The theorem is mainly based on the theory of models with indiscernibles.     

NdFeO3纳米晶的合成及气敏性能

以Nd2O3,Fe(NO3)3·9H2O,硝酸(1∶1)为原料,在柠檬酸体系中用溶胶凝胶法合成了具有钙钛矿结构的稀土复合氧化物NdFeO3;用XRD和TEM对产物的组成、颗粒大小、形貌进行了表征;结果表明:产物为纳米颗粒,平均粒径为28nm左右,且颗粒均匀。还采用静态配气法测试了材料的气敏性能,发现NdFeO3对H2S有很高的灵敏度,且抗干扰能力强,有较好的工业应用前景。     

Synthesis and Characterization of an Unexpected Asymmetric Binuclear Copper(I) Complex Containing 4-Vinyl-pyridine

Introduction Many examples of complexes containing the eight-membered ring M(-dppm)M' are known with a variety of metals, oxidation states and stereochemis-tries.1-4 In general, they contain trans-bound, bridging dppm ligands to give a planar M2P4 core structure with the two metal atoms held in close proximity to each other (regardless of whether a metal-metal bond is pre-sent or not). This feature is presumably one of the chief reasons for the unusual bonding, reactivity and catalytic prope…     

A Green and Efficient Synthesis of Xanthenedione Derivatives Promoted by InCl_3·4H_2O in Ionic Liquid

Xanthenedione derivatives have held considerable interests in recent years, since theyconstitute a structural unit in a number of natural products1 and have been used asversatile synthons because of the inherent reactivity of the inbuilt pyran ring2. Usually,poly-hydrogenated xanthenediones (3, Scheme 1) can be obtained through the acid orbase catalyzed condensation of appropriate active methylene carbonyl compounds withaldehydes. But this method is not very satisfactory because of the prolong…     

Revisit of wall‐induced lateral migration in particle electrophoresis through a straight rectangular microchannel: Effects of particle zeta potential

Previous studies have reported a lateral migration in particle electrophoresis through a straight rectangular microchannel. This phenomenon arises from the inherent wall‐induced electrical lift that can be exploited to focus and separate particles for microfluidic applications. Such a dielectrophoretic‐like force has been recently found to vary with the buffer concentration. We demonstrate in this work that the particle zeta potential also has a significant effect on the wall‐induced electrical lift. We perform an experimental study of the lateral migration of equal‐sized polystyrene particles with varying surface charges under identical electrokinetic flow conditions. Surprisingly, an enhanced focusing is observed for particles with a faster electrokinetic motion, which indicates a substantially larger electrical lift for particles with a smaller zeta potential. We speculate this phenomenon may be correlated with the particle surface conduction that is a strong function of particle and fluid properties.     

An Efficient Preparation of 2, 3-Disubstituted Indole Derivatives Induced by Low-valent Titanium

An efficient synthesis of 2, 3-disubstituted indole derivatives through low-valent titanium induced reductive cyclization of acylamido carbonyl compounds is described.     

Rapid quantification of four major bioactive alkaloids in Corydalis decumbens (Thunb.) Pers. by pressurised liquid extraction combined with liquid chromatography-triple quadrupole linear ion trap mass spectrometry

A new method based on pressurised liquid extraction (PLE) followed by liquid chromatography-triple quadrupole linear ion trap mass spectrometry (LC-QTrap-MS) analysis has been developed for the identification and quantification of four major alkaloids in extracts of Corydalis decumbens (Thunb.) Pers. PLE extractions were performed using 90% ethanol; temperature was set at 100 °C and pressure at 1500 psi. HPLC analysis was performed on a Waters XBridge™ C₁₈ column (150 mm × 2.1 mm i.d., 3.5 μm) eluted by a mobile phase of acetonitrile and 0.2% acetic acid. Data acquisition was carried out in multiple reaction monitoring transitions (MRMs) mode, monitoring two MRM transitions to ensure an accurate identification of target compounds in the samples. Additional identification and confirmation of target compounds were performed using the enhanced product ion modus (EPI) of the linear ion trap. The novel LC-QTrap-MS platform offers the best sensitivity and specificity for characterization and quantitative determination of the four alkaloids in C. decumbens (Thunb.) Pers. and fulfils the quality criteria for routine laboratory application.     

Synthesis of 1,2-allenic ketones through oxidation of homopropargyl alcohols with CrO_3(cat.)/TBHP under MWI

A CrO₃ catalyzed oxidation of homopropargyl alcohols with tert-butyl hydroperoxide under microwave irradiation was found to be an efficient and rapid alternative for the preparation of 1,2-allenic ketones.The advantages of this procedure include short reaction time,less adverse impact on the environment and reasonably high efficiency.     

Searching for a neutral top-Higgs in association with top-quark pairs at an e~+e~- collider in the TC2 model

We investigate the associated production of the neutral top-Higgs h_t⁰ with a pair of top-quarks in the context of the topcolor-assisted technicolor (TC2) model at the future e⁺e^- Linear Colliders (LC) i.e. e⁺e^- → tt h_t⁰. We calculate the production rate and present the distributions of the transverse momenta of top-Higgs and top-quarks. The results show that the total cross section is typically of the order of 1.0-7.5 fb in the energy range between 1000 GeV and 2000 GeV of the LC for the whole top-Higgs mass region of interest. It should be distinctly possible that hundreds or even thousands of h_t⁰ signals can be produced per year at the LC given the luminosity L=500 fb^-1.     

Hydrothermal synthesis and characteristics of 3-D hydrated bismuth oxalate coordination polymers with open-channel structure

Two new 3-D porous bismuth coordination polymers, (C₅NH₆)₂[Bi₂(H₂O)₂(C₂O₄)₄]·2H₂O 1 and (NH₄)[Bi(C₂O₄)₂]·3H₂O 2, have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic symmetry, P2₁/c space group with a=10.378(2) Å, b=17.285(3) Å, c=16.563(5) Å, α=90°, β=119.66(2)°, γ=90°, V=2581.8(10) Å³, Z=4, R₁=0.0355 and wR₂=0.0658 for unique 4713 reflections I >2σ(I). Compound 2 crystallizes in the tetragonal symmetry, I4₁/amd space group with a=11.7026(17) Å, b=11.7026(17) Å, c=9.2233(18) Å, α=90°, β=90°, γ=90°, V=1263.1(4) Å³, Z=32, R₁=0.0208 and wR₂=0.0518 for unique 359 reflections I> 2σ(I). Compounds 1 and 2 are 3-D open-framework structures with a 6⁶ uniform net, which consist of honeycomb-like layers connected to each other by oxalate units. While different guest molecules fill in their cavities of honeycomb-like layers, study of ultrasonic treatment on 2 indicates the replacement of NH₄⁺ by K⁺ on potassium ion exchange. Thermogravimetric analysis indicates that the open-channel frameworks are thermally stable up to 200 °C, and other characterizations are also described by elemental analysis, IR and ultraviolet-visible diffuse reflectionintegral spectrum (UV-Vis DRIS).