红色长余辉荧光粉Ca2Zn4Ti16O38:Pr3+的水热辅助合成及发光性质

采用水热法辅助合成了纯相Ca₂Zn₄Ti₁₆O₃₈:Pr³⁺荧光粉,初始n_Ca:n_Zn:n_Ti=2:4.1:15,煅烧条件为1 050 ℃空气气氛烧结5 h.并以X射线衍射、扫描电镜、紫外可见漫反射光谱和荧光光谱表征了样品的物相组成、微观形貌和光谱性质.合成的荧光粉在高温煅烧后仍较好地保持了球形的微观形态,优化的Pr³⁺掺杂浓度为0.015.Ca₂Zn₄Ti₁₆O₃₈:Pr³⁺荧光粉在471 nm波长激发下发射红光,发射谱通过高斯分峰拟合得到位于605、620和645 nm的3个发射峰,分别对应于Pr³⁺的¹D₂→³H₄,³P₀→³H₆和³P₀→³F₂跃迁.在471 nm波长激发下,Ca₂Zn₄Ti₁₆O₃₈:Pr³⁺的614 nm红光发射表现出超长余辉特性,表明该荧光粉是一种能被可见光有效激发的红色长余辉荧光粉.     

Eu3+离子在Ca2PbO4一维结构基质中的发光研究

A Eu³⁺-doped Ca₂PbO₄ with one-dimensional structure was prepared with a solid-state reaction method and its characteristics were investigated. The XRD results show that the substitution of Ca²⁺ by Eu³⁺ has no influence on the structure of Ca₂PbO₄. Under the excitation of ultraviolet light， the Ca₂PbO₄:Eu³⁺ phosphor exhibits strong red emission at about 618 nm which is assigned to the ⁵D₀- ⁷F₂ electric-dipole transition. The compounds Sr₂CeO₄ and Ca₂SnO₄ have the same crystal symmetry as that of Ca₂PbO₄ and it is found that the emission intensity of Ca₂PbO₄∶Eu³⁺ is higher than that of Sr₂CeO₄∶Eu³⁺ and lower than that of Ca₂SnO₄∶Eu³⁺. The excitation spectrum of Ca₂PbO₄∶Eu³⁺ appears to be a broad band with two peaks at about 289 nm and 340 nm. The former peak is attributed to the Eu³⁺-O₂- charge transfer transition， while the latter one may be related to the absorption of Ca₂PbO₄ host or its crystal defects.     

Sr3Al2O6∶Eu2+红色发光纳米晶的新型形貌与发光性能的研究

A red luminescent Sr₃Al₂O₆∶Eu²⁺ nanocrystallites with new morphology were synthesized by sol-gel route assisted by microwave irradiation. The phosphor powders were characterized by X-ray diffraction (XRD)， scanning electron microscopy (SEM) and fluorescence spectroscopy. The results reveal that the calcination temperature of the Sr₃Al₂O₆∶Eu²⁺ phosphor crystallites greatly affects its morphology. With temperature increasing， the phosphor crystallites morphology showed primarily from nanorod-like， mixture of nanorod and flower-like to homogeneous flower-like morphology. The effects of new morphology on luminescent properties of phosphors were investigated. Uniformly dispersed flower-like Sr₃Al₂O₆∶Eu²⁺ phosphor powders showed the strongest luminescent intensity and the longest afterglow time.     

不同温度下VUV光激发的Pr3+离子的发光性质

The luminescent properties of Pr³⁺-doped LaB₃O₆, SrAl₁₂O₁₉, SrB₄O₇ and NaYF₄ in the vaccum ultraviol-et (VUV) range at different temperatures were investigated under the excitation of high-energetic synchrotron radiation. For Pr³⁺ ions in LaB₃O₆, SrAl₁₂O₁₉ and SrB₄O₇, only the parity-forbidden ¹S₀→4f² transitions were observ-ed in the emission spectra at relatively low temperature; but the parity-allowed 4f5d→4f² transitions appeared simultaneously when the temperature was high enough. And the intensity of broad 4f5d→4f² emission increased relative to the intensity of ¹S₀→4f² emissions with increasing temperature. Then the thermal equilibrium model of energy levels was employed to the lowest 4f5d state and ¹S₀ state of Pr³⁺ in the three hosts. The calculated curves were in good agreement with the experimental values, indicating the occurrence of the thermal excitation from ¹S₀ state to 4f5d states at high temperatures when the lowest 4f5d state lies higher than ¹S₀ state and the photon energy is high enough.     

CuO/Sn0.8Ti0.2O2催化剂的表征及对NO+CO反应活性研究

Reducibility and characteristics of CuO/Sn_0.8Ti_0.2O₂ catalysts were examined by using a microreactor-GC NO+CO reaction system, BET, TG-DTA, FTIR, XRD and H2-TPR techniques. CuO/Sn_0.8Ti_0.2O₂ had high activity in NO+CO reaction, showing 93% NO conversion at 300 ℃ in air, and 100% NO conversion at 225 ℃ after H₂ pretreatment. The pore size distribution of Sn_0.8Ti_0.2O₂ was mainly as micro-pores and meso-pores (1~5 nm), and the specific surface area and total pore volume of Sn_0.8Ti_0.2O₂ were 69 m²·g^-1 and 0.15 cm³·g^-1, respectively. As shown by XRD analysis, there was no CuO crystal diffraction peak at 9%CuO loading, but two CuO crystal diffraction peaks at 2θ 35.5° and 38.7° were present at 12% CuO loading. FTIR detected the adsorption of NO and CO on the surface of reduced 12%CuO/Sn_0.8Ti_0.2O₂. The Cu²⁺ sites and support surface adsorbed NO, and the process of NO adsorption led to the formation of N₂O and NO₃^-. In contrast, the Cu⁺、Cu⁰ sites and support surface adsorbed CO, and when the mixed gases of NO and CO were adsorbed by support surface, no NO₃^- was formed. H₂-TPR showed four reduction peaks (α, β, γ and δ). The α, β and γ peaks were the reductions of CuO species, and the δ peak was the reduction of Sn_0.8Ti_0.2O₂.     

硬脂酸法制备超细K2La2Ti3O10及其酸交换性质研究

A new stearic acid method(SAM) has been used to prepare ultrafine K₂La₂Ti₃O₁₀ nanocrystalline. Each state of synthesis process was followed by the use of FT-IR analysis. The resulting materials have been characterized by means of XRD， TEM， BET surface area analysis. The acid-exchanging property of the obtained product was also studied. The experimental results showed that comparing with the product of traditional solid-state reaction， the particle size of the K₂La₂Ti₃O₁₀ synthesized by SAM is greatly reduced， BET surface area is high(more than 11.83m²·g^-1) and has different acid-exchanging properties. It can be easily exfoliated in 2mol·L^-1 HNO₃ so-lution.     

Eu3+掺杂SiO2-B2O3-NaF玻璃的制备及发光性质

The Eu-doped SiO₂-B₂O₃-NaF glass was prepared by sol-gel process, using tetraethoxy Silicane, boric acid and sodium fluoride as starting materials, 0.10 mol·L^-1 EuCl₃ solution as the dopant. The luminescent properties of Eu³⁺ doped SiO₂-B₂O₃-NaF phosphors were investigated. The phosphors showed prominent luminescence in pink, the strong emission of Eu³⁺ comes from electronic transition of ⁵D₀- ⁷F₁（591 nm）and ⁵D₀- ⁷F₂（615 nm）,which derived from two transition modes of magnetic-dipole and electric-dipole .The peak intensity of 591nm in SiO₂-B₂O₃-NaF matrix is much stronger than it in the other matrixes, it means that SiO₂-B₂O₃-NaF has sensitization on the transition of ⁵D₀- ⁷F₁ (Eu³⁺). If there are broad bonds in the range of 275～380 nm in the excitation spectrum of Eu³⁺ -doped SiO₂-B₂O₃-NaF glass, the emission peak intensity should be intensified. It is because the electron migration CT band of O^2--Eu³⁺. For all Eu³⁺ concentrations used, the investigation found that when the mass of fraction got to 29.19×10^-3, the luminescence intensity reached the summit. And there is a phenomenon of concentration quenching. Investigation with the same concentration of Eu³⁺ at different annealed temperature, we found that the sample annealed at 400 ℃, the luminescence intensity achieved its maximum value, and Eu³⁺ in this matrix had a phenomenon of temperature quenching. The structural characterization of these luminescent materials was carried by used XRD and TEM. The result showed that the phosphor was in amorphous phase.     

水热法制备具有光滑表面的球形Y2O3∶Eu3+发光材料

The spherical Y₂O₃∶Eu³⁺ luminescent particles with size of 0.5～3 μm and smooth surface were synthesized by hydrothermal method. The resulted Y₂O₃∶Eu³⁺ precursors and the calcined particles were characterized by differential thermal analysis (DTA) and thermogravimetric (TG) analysis, X-ray diffraction (XRD), Fourier-transform IR spectroscopy (FTIR), scanning electron microscopy (SEM) and photoluminescence spectra (PL). FTIR, TG-DTA, XRD measurements show that the precursors are crystal with hydroxyl and carbonate group, and the pure cubic yttria is obtained after annealing above 700 ℃. The SEM images indicate that the Y₂O₃∶Eu³⁺ particles are in spherical shape and with smooth surface. PL analysis shows that the particles present characteristic red emission of Eu³⁺.     

Sr3SiO5∶Eu2+荧光粉的微波合成及性能研究

Silicate orange yellow phosphor used in white-light LED was prepared by microwave method. The structure and optical properties of phosphor were studied. Sr₃SiO₅∶Eu²⁺ phosphor synthesized by microwave method is tetragonal structure of Sr₃SiO₅ with uniform particle distribution. Luminescence spectrum is a broad band spectrum peaking at 575 nm. The peak of excitation is at 532 nm and phosphor can be excited by blue LED. The warm white light was obtained combined phosphor and blue LED. The CIE chromaticity coordinates and correlated color temperature of white light is (x=0.394, y=0.341) and 3 239 K respectively.     

LiNi0.8Co0.2O2 / MWNTs复合物超级电容器电极材料的研究

Multiwalled carbon nanotubes (MWNTs) were used as the conductive additive in the electrode materials. The electrochemical properties of supercapacitors based on LiNi_0.8Co_0.2O₂ / MWNTs composite and LiNi_0.8Co_0.2O₂/acetylene black composite and MWNTs in 1.0 mol·L^-1 LiClO₄ / EC+DEC [V(EC)∶V(DEC)=1∶1] electrolyte were investigated by means of constant charge/discharge current tests, respectively. The experimental results show that the LiNi_0.8Co_0.2O₂ / MWNTs composite has better performance than that of others, and the maximum specific capacitance of the supercapacitor can reach 271.6 F·g^-1, while the energy density is up to 339.5 Wh·kg^-1. Furthermore, it is remarkable that the performance of MWNTs is better than that of acetylene black as the conductive additive.     

The Synthesis of 13C9-15N-Labeled 3,5-Diiodothyronine and Thyroxine

Thyroid hormones undergo extensive metabolism to regulate hormone activity. A labeled thyroid hormone would be useful to track hormone metabolism through various pathways. While radiolabeled thyroid hormones have been synthesized and used for in vivo studies, a stable isotope labeled form of thyroid hormone is required for studying thyroid hormone metabolism by LC-MS/MS, an analytical technique that has certain advantages without the complications of radioactivity. Here we report the synthesis of ¹³C₉-¹⁵N-T₂ and ¹³C₉-¹⁵N-T₄, two labeled thyroid hormone derivatives suitable for in vivo LC-MS/MS studies.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Ab initio investigations of the bound rovibrational levels of NeH 2 + , NeHD+, and NeD 2 +

Summary Bound rovibrational levels have been calculated for NeH ₂ ⁺ , NeHD⁺, and NeD ₂ ⁺ using three recent fits to an accurateab initio PES. The NeH ₂ ⁺ molecule behaves essentially as a linear molecule, the predicted rotational constant is 2.57 cm^–1. The fundamental frequencies are 811, 1189, and 1748 cm^–1 for the Ne-H ₂ ⁺ stretch, the Ne-H ₂ ⁺ bend and H ₂ ⁺ stretching modes, respectively.Dedicated to the 60th birthday of Prof. W. Kutzelnigg, Bochum     

X-ray Crystal Structure of (CNSSS)2(M)2 (M = AsF6 −, SbF6 −, Sb2F11 −)

The crystal structures of (CNSSS)₂(AsF₆)₂, (CNSSS)₂(SbF6)₂, and two phases of (CNSSS)₂(Sb₂F₁₁)₂ have been determined. The AsF₆ ^?, SbF₆ ^?, and α-Sb₂F₁₁ ^? salts crystallize as reddish-brown plates whereas the β-Sb₂F₁₁ ^? salt crystallizes as green rods. The dication ^ß+SSSNCCNSSS^+ß (1²⁺) is the same in all four structures and consists of two 7π rings linked by a sp²-sp² C-C bond (1.462 Å in 1 (AsF₆)₂). The packing in the four structures is similar with stacks of dications along the a-axis and alternating sheets of dications and anions lying in the bc-plane. The differences in the dication-dication contacts is reflected in the variable temperature magnetic data.     

Freezing-point of mixtures of H 2 16 O and H 2 18 O

Freezing-point depression of mixtures of H ₂ ¹⁶ O and H ₂ ¹⁸ O were measured. The results showed that the freezing point of the mixture rose linearly with an increase in the molal concentration of H ₂ ¹⁸ O. The results suggested the formation of a solid solution of H ₂ ¹⁶ O and H ₂ ¹⁸ O by freezing, similar to that formed by H ₂ O–D ₂ O, and that H ₂ ¹⁸ O behaves as a different molecule than H ₂ ¹⁶ O.     

Ca2+-Mg2+-Zn2+体系在水溶性聚磷酸铵溶液中螯合规律的研究

近年来,水溶性聚磷酸铵在液体肥料和复合肥料的领域受到了广泛的关注,并在发达国家中得到了大面积的推广及应用。在pH值为5.5~8.0、温度为278.15 K~323.15 K的条件下,本文采用滴定法研究Ca_²⁺-Mg_²⁺-Zn_²⁺体系在聚磷酸铵溶液中的螯合规律。实验结果表明：相同质量分数的聚磷酸铵溶液对金属离子的螯合量会随着体系中Ca_²⁺、Mg_²⁺、Zn_²⁺的摩尔浓度的变化而变化;随着温度的升高而逐渐降低;随着pH的增加而逐渐增加;随着聚合度的升高而逐渐增加。采用傅里叶红外光谱对聚磷酸铵和A₁B₃C₃体系的螯合物进行表征。     

A mass spectrometric method to determine activities of enzymes involved in polyamine catabolism

An analytical method for the determination of three polyamines (putrescine, spermidine, and spermine) and five acetylpolyamines [N¹-acetylspermidine (N¹AcSpd), N⁸-acetylspermidine (N⁸AcSpd), N¹-acetylspermine, N¹,N⁸-diacetylspermidine, and N¹,N¹²-diacetylspermine] involved in the polyamine catabolic pathway has been developed using a hybrid tandem mass spectrometer. Heptafluorobutyryl (HFB) derivatives of these compounds and respective internal standards labeled with stable isotopes were analyzed simultaneously by TOF MS, based on peak areas appearing at appropriate m/z values. The isomers, N¹AcSpd and N⁸AcSpd were determined from their fragment ions, the acetylamidopropyl and acetylamidobutyl groups, respectively, using MS/MS with ¹³C₂-N¹AcSpd and ¹³C₂-N⁸AcSpd which have the ¹³C₂-acetyl group as an internal standard. The TOF MS method was successfully applied to measure the activity of enzymes involved in polyamine catabolic pathways, namely N¹-acetylpolyamine oxidase (APAO), spermine oxidase (SMO), and spermidine/spermine N¹-acetyltransferase (SSAT). The following natural substrates and products labeled with stable isotopes considering the application to biological samples were identified; for APAO, [4,9,12-¹⁵N₃]-N¹-acetylspermine and [1,4,8-¹⁵N₃]spermidine (¹⁵N₃-Spd), respectively; for SMO, [1,4,8,12-¹⁵N₄]spermine and ¹⁵N₃-Spd, respectively; and for SSAT, ¹⁵N₃-Spd and [1,4,8-¹⁵N₃]-N¹-acetylspermidine, respectively.     

Syntheses, crystal structures and Raman spectra of Ba(BF4)(PF6), Ba(BF4)(AsF6) and Ba2(BF4)2(AsF6)(H3F4); the first examples of metal salts containing simultaneously tetrahedral BF4 and octahedral AF6 anions

In the system BaF₂/BF₃/PF₅/anhydrous hydrogen fluoride (aHF) a compound Ba(BF₄)(PF₆) was isolated and characterized by Raman spectroscopy and X-ray diffraction on the single crystal. Ba(BF₄)(PF₆) crystallizes in a hexagonal space group with a=10.2251(4) Å, c=6.1535(4) Å, V=557.17(5) Å³ at 200 K, and Z=3. Both crystallographically independent Ba atoms possess coordination polyhedra in the shape of tri-capped trigonal prisms, which include F atoms from BF₄⁻ and PF₆⁻ anions. In the analogous system with AsF₅ instead of PF₅ the compound Ba(BF₄)(AsF₆) was isolated and characterized. It crystallizes in an orthorhombic Pnma space group with a=10.415(2) Å, b=6.325(3) Å, c=11.8297(17) Å, V=779.3(4) Å³ at 200 K, and Z=4. The coordination around Ba atom is in the shape of slightly distorted tri-capped trigonal prism which includes five F atoms from AsF₆⁻ and four F atoms from BF₄⁻ anions. When the system BaF₂/BF₃/AsF₅/aHF is made basic with an extra addition of BaF₂, the compound Ba₂(BF₄)₂(AsF₆)(H₃F₄) was obtained. It crystallizes in a hexagonal P6₃/mmc space group with a=6.8709(9) Å, c=17.327(8) Å, V=708.4(4) Å³ at 200 K, and Z=2. The barium environment in the shape of tetra-capped distorted trigonal prism involves 10 F atoms from four BF₄⁻, three AsF₆⁻ and three H₃F₄⁻ anions. All F atoms, except the central atom in H₃F₄ moiety, act as μ₂-bridges yielding a complex 3-D structural network.     

激光等离子体反应生成的AgP+n、AumP+n的结构分析

原子簇化合物的合成方法,由于条件限制,只有B、C、St等非金属元素与过渡金属袈基化合物等较为成熟．贵金属原子簇的合成则较困难．然而,应用激光等离子体反应,可使周期表内几乎所有元素都生成原子簇,为原子簇的生成与研究提供了一条新途径．该方法生成的原子簇在飞行时间质谱仪上可记录到一系列信号,某些信号呈现区域极大（或被称为‘匈数’吵］．郑兰芬等用纯化的红磷粉分别与金粉、银粉混合,在激光等离子作源飞行时间质谱仪上得到一系列谱图【2］：ig与P作用只得到单核xg与P形成的lgy：iE离子簇．谱图较简单,＊沪X最大可达叱叱…     

Molecular orbitals studies on two limiting structures of conjugated vinyl cation,C4H4F+

Nonempirical LCAO-MO-SCF calculations employing STO-3G minimal basis set have been carried out to examine the two limiting, open and bridged, structures of a conjugative fluorovinyl cation system and the interconversion of these two structures. The bridged ion is found to be 37.6 kcal/mole higher in energy than the open ion. Three pathways of converting the open ion to bridged ion were investigated. The pathway in which conjugation is preserved along the reaction profile gives the lowest energy barrier and depicts the bridged ion as a transition state.     

氨基酸-BrO-3-Mn2+-H2SO4-丙酮体系的振荡反应

This paper, Using potentiometric method, first reports the oscillating behavior of five amino acids (L-methionine, L-cystine, L-tryptophan, L-serine, L-tyrosine) in a new oscillating system of amino acid-BrO_3~--Mn~(2+)-H_2SO_4-acetone. The effect of many factors on oscillation have been investigated. According to Arrhenius equation, the apparent activation energy of the oscillatary induction period and oscillation period of five oscillating systems are obtained within temperature range of 20～37 ℃.