溴代烷烃与活性氮的反应发光研究

在流动余辉装置上, 利用N₂空心阴极放电制备活性氮, 研究了活性氮与溴代烷烃(CHBr₃、CH₂Br₂、C₂H₅Br、C₄H₉Br) 反应的化学发光.上述所有反应中, 在550～750 nm波段均观察到了较强的NBr (b¹Σ+→X³Σ^-)跃迁发射谱. 同时在活性氮与CHBr₃和CH₂Br₂的反应中, 在流动管下游还观察到了CN (A²π, B²π→X²Σ⁺)的发射谱. 验证性的实验表明, 激发态NBr (b¹Σ⁺)是由二步过程形成: N(⁴S)与溴代烷烃反应生成NBr (X³Σ^-), 再通过N₂ (A ³Σ_u⁺)分子能量转移到激发态NBr (b¹Σ⁺); 而激发态的CN是通过N(⁴S) + CBr→CN(A, B) + Br过程形成的.     

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.     

Ni-Co双金属催化剂上沼气重整制氢机理

用传统湿式浸渍法制备了La₂O₃掺杂的商业γ-Al₂O₃负载的沼气重整催化剂Ni-Co/La₂O₃-γ-Al₂O₃, 并用程序升温加氢(TPH)、程序升温氧化(TPO)、程序升温表面反应(TPSR)、程序升温脱附(TPD)及脉冲实验对催化剂进行了表征. 结果表明, 沼气重整过程中Ni-Co/La₂O₃-γ-Al₂O₃催化剂上的表面碳物种主要来源于CH₄的裂解, CO₂的贡献很小. CH₄裂解能够产生三种活性不同的碳物种, 即C_α、C_β与C_γ. 随着反应的进行, C_α物种减小而C_β与C_γ物种增加, 且C_γ物种能够转变为惰性的石墨碳. 重整反应过程中CH₄与CO₂的活化能相互促进. 催化剂表面的O物种与C反应生成CO或与CH_x反应生成CH_xO再分解为CO与吸附态的H物种, 可能是Ni-Co/La₂O₃-γ-Al₂O₃催化剂上沼气重整的速率控制步骤.     

Tm3+/Er3+/Ho3+共掺SiO2-Bi2O3-AlF3-BaF2玻璃发光性能

采用高温熔融法制备了Tm³⁺/Er³⁺/Ho³⁺共掺的铋硅酸盐50SiO₂-40Bi₂O₃-5AlF₃-5BaF₂玻璃。研究了在808 nm激光器（Laser Diode）激发下Tm³⁺/Er³⁺/Ho³⁺共掺的铋硅酸盐在2 060 nm处的发光性能,同时测试及分析了该铋硅酸盐玻璃的差热特性、吸收光谱及荧光光谱。根据吸收光谱以及Judd-Oflet理论,计算了Ho³⁺的Judd-Oflet强度参数Ω_t（t=2,4,6）以及Tm³⁺/Er³⁺/Ho³⁺相应的吸收截面。铋硅酸盐玻璃中,Tm₂O₃、Er₂O₃和Ho2O3掺杂浓度分别为0.75%、1.0%和0.5%时,2 060 nm处Ho³⁺∶⁵I₇→⁵I₈发射峰强度达到最大。对Tm³⁺/Er³⁺/Ho³⁺ 3种离子的光谱性质和离子间可能存在的能量传递也做了分析。Ho³⁺在1 953 nm处的最大吸收截面σ_abs为9.08×10^-21 cm²,在2 060 nm处的最大发射截面σem为11.68×10^-21 cm²,辐射寿命τ_mea为2.75 ms,具有良好的增益效应σ_emτ（3.212×10^-20 cm^-2·ms）。     

新半金属Fe2LaO4磁电性能的第一性原理计算

利用基于密度泛函理论的第一性原理赝势法设计并优化了含稀土元素的新半金属Fe₂LaO₄。详细计算了其电荷分布,分子磁矩等磁电性能，并结合配位场理论分析了其电子结构。结果表明，Fe₂LaO₄是一种含稀土元素的铁磁性的新ⅡB型半金属；它的稳定相晶格常数约为0.623 nm，分子磁矩约为1.0μ_B；Fe₂LaO₄属软铁磁性半金属；La较多的外层电子增强了Fe₂LaO₄内部的库仑斥力,导致了配合物ML₄和ML₆均受强场作用,从而使Fe₂LaO₄具有软铁磁性；考虑自旋分布后ML₄和ML₆的电子结构分别为a_1g¹↑a_1g¹↓t_1u³↑t_1u³↓e_g²↑e_g²↓t_2g³↑t_2g³↓和a_1g¹↑a_1g¹↓t_1u³↑t_1u³↓t_2g³↑t_2g³↓e_g²↑e_g²↓e_g^*1↑,这些电子属于分子轨道。     

白光LED用Sr0.955Al2Si2-xTixO8：Eu2+荧光粉的晶体结构和光谱特性

由高温固相反应制得Sr_0.955Al₂Si_2-xTi_xO₈：Eu²⁺（x=0~1.0）系列试样,研究了Ti⁴⁺置换Si⁴⁺对其晶体结构和光谱特性的影响。Ti⁴⁺以类质同相替代Si⁴⁺进入晶体晶格中,形成了连续固溶体,其晶胞参数a,b,c,β和晶胞体积V随Ti⁴⁺置换量呈线性递增。Ti⁴⁺置换Si⁴⁺对晶胞参数c的影响显著,b其次,a最小。荧光激发谱为宽带,位于230~400nm,由267nm、305nm、350nm和375nm 4个峰拟合成,表观峰值位于351nm;随着Ti⁴⁺置换量的增加,半高宽（FWHM）从105nm减小到93nm。发射光谱位于380~600nm,表观峰值位于407nm,可由406nm和441nm两峰拟合而成并且随Ti⁴⁺置换量增加线性红移,Ti⁴⁺进入晶格对长波长发射中心影响较少;Ti⁴⁺置换量为1.0时,表观发射峰位从407nm红移至417nm;利用试样荧光光谱和VanUitert经验公式,得出SrAl₂Si₂O₈：Eu²⁺中Sr²⁺的配位数为9。随着Ti⁴⁺置换量Si⁴⁺进入基质晶格,造成Eu-O距离变小,使得Eu²⁺所处的晶体场强度增强,发光中心Eu²⁺的5d能级分裂增大,造成Eu²⁺最低发射能级重心下移,两拟合谱峰峰位均呈线性红移。     

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.     

掺镍型层状LixNiyMn1-yO2正极材料的合成与电性能研究

A kind of cathode material of layered Li_xNi_yMn_1-yO₂ characterized with the O2 type has been synthesized by a simple method. Its precursor Na_xNi_yMn_1-yO₂ has been prepared from manganese dioxide， nickel hydroxide and sodium carbonate at high temperature in air and quickly cooled in cold water， then it has been exchanged by the melted LiNO₃ at 300～400℃ in air. The effects of calcine-temperature for the precursors and its compositions (the content of Na and Ni) on the electrochemical properties of the material Li_xNi_yMn_1-yO₂ have been investingated by XRD and electrochemical tests. The results show that the sample Li_0.7Ni_0.3Mn_0.7O₂， has the best electrochemical properties which shows only one charge-discharge potential stage of 2.8～3.0V and has a high specific capacity over 180mAh·g^-1 cycled between 2.0～4.20V. A significant structure transformation to the spinal-type phase has not been found in the charge-discharge cycling and the discharge specific capacity around 165mAh·g^-1 has re-mained after the 20th cyclings for the material.     

VB2n-(n=8~12)团簇几何结构、电子及热力学特性的理论研究

基于卡里普索结构预测程序和密度泛函理论的第一性原理计算,搜索确定了VB_2n^-（n=8~12）团簇的基态和亚稳态结构。结果发现,V原子的掺杂完全改变了原硼团簇的结构并提高了原体系的稳定性。掺杂体系基态结构分别呈现高对称性的鼓状（VB₁₆^-：C_2v）、管状（VB₁₈^-：C_2v和VB₂₀^-：C_s）及笼状（VB₂₂^-：C₂和VB₂₄^-：D_3h）结构。基于基态结构,研究了体系的电荷转移和极化率,拟合出了光电子能谱、红外和拉曼谱图,分析了流变键和芳香特性。最后,研究了体系的热力学特性,讨论了温度对热力学参数的影响。     

C2H4在Fe3C(100)表面吸附及脱氢裂解的密度泛函理论研究

采用自旋极化密度泛函理论和周期平板模型,对C₂H₄在铁基费托合成催化剂活性相之一Fe₃C（100）表面从热力学和动力学两个方面分析了C₂H₄在Fe₃C（100）表面进行脱氢和裂解反应的竞争性。结果表明,C₂H₄在Fe₃C（100）表面的μ-bridging吸附比π、di-σ吸附更加稳定;C₂H₄与Fe₃C（100）面的相互作用导致C₂H₄的C原子部分发生重新杂化（sp²→sp³）,使C原子呈近四面体结构。在Fe₃C（100）表面C₂H₄易于发生脱氢反应,C-C键裂解反应不具有竞争性。亚乙烯基CCH₂和乙烯基CHCH₂是Fe₃C（100）表面最丰的C₂物种,或是C₂H₄参与链增长的主要单体形式。     

新型复合分子筛的合成和催化应用

 系统地归纳总结了最近几年引起人们广泛关注的复合分子筛的研究进展,包括微孔-微孔复合分子筛、微孔-介孔复合分子筛、微孔-大孔复合分子筛及微孔-介孔-大孔复合分子筛的合成和应用近况. 并对复合分子筛的发展前景进行了展望.     

Physicochemical and Rheological Properties of Novel Magnesium Salt-Polyacrylamide Composite Polymers

Two series of novel inorganic-organic composite polymers have been prepared through physical blending of magnesium chloride and magnesium hydroxide respectively with polyacrylamide aqueous solution. The physicochemical properties of the magnesium salt-polyacrylamide composite polymers were tuned by varying the ratio between the magnesium salt (e.g., magnesium chloride and magnesium hydroxide) and polyacrylamide. Characterizations of magnesium salt-polyacrylamide composite polymers were carried out via FTIR and TEM. Parameters such as solution conductivity and viscosity were also taken into account to characterize the physicochemical properties of the composite polymer aqueous solutions. Magnesium chloride-polyacrylamide (MCPAM) composite polymer aqueous solutions have a higher conductivity compared to magnesium hydroxide-polyacrylamide (MHPAM) composite polymer aqueous solutions. The viscosities of the MHPAM composite polymer aqueous solutions were found higher than MCPAM composite polymer aqueous solutions. The rheological properties of the composite polymer aqueous solutions were investigated using steady-state flow and oscillatory frequency sweep within the linear viscoelastic region. Shear-thinning effect was observed for both composite polymer systems when the shear rate increases. In oscillatory frequency sweep tests, both composite polymer systems show that the viscoelastic behaviors depend strongly on the magnesium salt concentrations. Viscous behavior was found to be dominant for both composite polymer systems.     

苯甲酸在疏水性复合电极上的电化学还原行为

以铜片和锌片为基材,复合电镀制得Cu-PTFE(聚四氟乙烯)和Zn-PTFE疏水性复合电极,并将复合电极应用于苯甲酸的电化学还原行为研究。测定了复合电极在电解液中的Tafel极化曲线、循环伏安、电极稳定性和交流阻抗等电化学参数。结果表明,在苯甲酸电还原制备苯甲醛中,Cu-PTFE复合电极相对于Zn-PTFE复合电极具有较高的催化活性,其电还原产率分别为88.4%和79.2%,因此,Cu-PTFE复合电极有望成为苯甲酸电化学还原制备苯甲醛的电极材料。电化学行为的研究结果显示,苯甲酸在疏水性复合电极上的电还原过程可能只受电子迁移过程控制。     

磷钼酸/聚苯乙烯/聚乙烯醇电纺纤维膜的制备及性能

采用静电纺丝法制备了磷钼酸/聚苯乙烯(PS)/聚乙烯醇(PVA)复合纤维,并将其模压成膜.利用红外光谱(IR)、扫描电子显微镜(SEM)及X射线能谱(EDX)等对复合纤维及其膜的结构与形貌进行表征,并对复合纤维膜的光催化性能、力学性能及在水中稳定性进行测试.结果表明,在复合纤维中磷钼酸的Keggin结构得到保持.PS与PVA质量比为1∶1时,复合纤维形貌最佳,表面光滑,直径较小且分布均匀,复合纤维的直径随着磷钼酸含量的增加而减小.将磷钼酸固载于复合纤维膜上比直接使用具有更高的光催化活性,光照25 min后接近98%的甲基橙降解;复合纤维膜易于回收再利用,5次重复使用后,复合纤维膜没有破损,磷钼酸损失较少,光催化性能无明显下降.复合纤维膜的强度随磷钼酸含量的增加先增大后减小,韧性随PVA含量的增加而增大,随磷钼酸含量的增加而减小.     

Cellulose–halloysite nanotube composite hydrogels for curcumin delivery

Halloysite nanotubes (HNTs) were added to cellulose NaOH/urea solution to prepare composite hydrogels using epichlorhydrine crosslinking at an elevated temperature. The shear viscosity, mechanical properties, microstructure, swelling properties, cytocompatibility, and drug delivery behavior of the cellulose/HNT composite hydrogels were investigated. The viscosity of the composite solution increases with the addition of HNT. The compressive mechanical properties of composite hydrogels are significantly improved compared with pure cellulose hydrogel. The compressive strength of the composite hydrogels with 66.7% HNTs is 128 kPa, while that of pure cellulose hydrogel is only 29.8 kPa in compressive strength. Rheological measurement suggests the resistance to deformation is improved for composite hydrogels. X-ray diffraction and Fourier transform infrared spectroscopy show that the crystal structure and chemical structure of HNT are not changed in the composite hydrogels. Hydrogen bonding interactions between HNT and cellulose exist in the composites. A porous structure of the composite hydrogels with pore size of 200–400 μm was found by scanning electron microscopy. The addition of HNT leads to decreased swelling ratios in NaCl solution and pure water for the composite hydrogels. Cytotoxicity assays show that the cellulose/HNT composite hydrogels have a good biocompatibility with MC3T3-E1 cells and MCF-7 cells. Curcumin is further loaded into the composite hydrogel via physical adsorption. The curcumin-loaded composite hydrogels show a strong inhibition effect on the cancer cells. All the results illustrate that the cellulose/HNT composite hydrogels have promising applications such as anticancer drug delivery systems and anti-inflammatory wound dressings.     

具有抗菌性能的载药复合微纳米纤维的制备及其结构和性能表征

利用静电纺丝技术制备了一种具有抗菌性能的氧化锌(ZnO)/聚乳酸(PLA)/聚己内酯(PCL)载药微纳米纤维膜,并通过扫描电子显微镜(SEM)、X射线衍射(XRD)和傅里叶变换红外光谱(FTIR)分别对复合膜的表面形态、元素组成和化学结构进行表征。通过抗菌实验评价了复合膜的抗菌性能,用紫外分光光度计测试复合膜在体外的药物释放行为。结果显示,以物理共混的方式将ZnO和氢溴酸高乌甲素(LAH)成功载入复合微纳米纤维;与PLA/PCL复合微纳米纤维膜相比,ZnO/PLA/PCL复合微纳米纤维膜表现出更好的抗菌效率。当ZnO含量为10%(wt)时,复合微纳米纤维膜具有最佳的抗菌性能;药物释放性能结果表明,ZnO/PLA/PCL复合微纳米纤维膜具有良好的药物缓释性能。     

复合电沉积的最新研究动态

综述近年来国内外复合电沉积技术最新研究动态.重点探讨纳米复合镀层,电催化复合镀层以及光活性复合镀层等方面的研究现状和发展趋势.纳米复合镀层比一般的复合镀层具有更高的硬度,更好的耐磨性和耐蚀性;电催化复合镀层则可在纯金属电极,合金电极的基础上进一步降低电极反应的过电位.以金属氧化物,导电聚合物作为基质材料的电催化复合镀层已为现代复合电沉积技术开辟了一个新领域.     

Electrochemical Properties of Hollow‐Structured MnS–Carbon Nanocomposite Powders Prepared by a One‐Pot Spray Pyrolysis Process

Spherical, hollow MnS? C composite powders were prepared from a solution of manganese salt, thiourea, and sucrose by one‐pot spray pyrolysis. The MnS? C composite powders were generated by direct sulfidation of MnO with hydrogen sulfide gas generated in situ by decomposition of thiourea during spray pyrolysis. Sucrose, which is used as a carbon source material, plays a key role in the formation of the MnS? C composite powders by improving the reducing atmosphere around the powders. Dot‐mapping images of the composite powders demonstrated uniform distribution of the manganese, sulfur, and carbon components within the MnS? C composite powder. Fine crystals of MnS were uniformly mixed with carbon derived from polymerization and carbonization of sucrose. The carbon content of the MnS? C composite powders was 26 wt %. The discharge capacities of the MnS? C composite powders in the 2nd and 200th cycles were 863 and 967 mA h g^?1, respectively, at a current density of 1000 mA g^?1. The spherical and hollow morphology of the MnS? C composite powders was completely retained, even after 200 cycles. The enhanced cycling and rate performance of the MnS? C composite powders is ascribed to the structural stability of the composite powders.     

纳米TiO2-SiO2复合氧化物的制备与性质

采用溶胶-凝胶结合CO2超临界干燥方法制备了比表面积大、热稳定性好的纳米TiO2-SiO2复合氧化物.考察了原料组成和焙烧温度对复合氧化物比表面积、热稳定性和酸性的影响,通过加氢脱硫反应考察了该复合氧化物作为加氢精制催化剂载体的可行性.结果表明,采用该方法制备的复合氧化物为纳米颗粒,在n(Ti)/n(Si)=1时,其比表面积和孔容最大;与纯TiO2相比,引入SiO2明显提高了复合氧化物的热稳定性和晶型稳定性;以此复合氧化物为载体的加氢精制催化剂具有很好的低温脱硫活性,TiO2-SiO2复合氧化物载体的酸性特征影响了催化剂的加氢脱硫活性.     

脉冲电化学驱动壳聚糖原位调控制备羟基磷灰石/银复合涂层

采用脉冲电化学驱动壳聚糖原位调控制备了具有抗菌性的羟基磷灰石/银纳米复合涂层.考察了电解液中银离子浓度、钙磷盐浓度等对复合涂层的形貌及成分的影响.探讨了壳聚糖调控羟基磷灰石和银纳米粒子的形成机理,发现在本研究的较佳实验条件为电位-1.3 V,Ag~+浓度为0.06 g·L~(-1),Ca~(2+)浓度为5 mmol·L~(-1).在此基础上对复合涂层的生物活性、生理稳定性能、抗菌性能进行分析.结果表明:复合涂层呈纳米球状,由羟基磷灰石、银、壳聚糖三相组成,并且表面有一层壳聚糖覆盖.银纳米粒子和羟基磷灰石纳米粒子在复合涂层中均匀分布.将复合涂层浸泡在SCPS溶液中37°C浸泡矿化10天后,在复合涂层表面生产细针状排列整齐的羟基磷灰石,且在(002)晶面25.8°处发生显著择优生长,表明复合涂层在快速矿化液中能诱导磷灰石生成,生物活性好.将复合涂层浸泡在37°C PBS溶液中考察其生理稳定性,壳聚糖对复合涂层中Ca~(2+)和Ag~+实现双重离子释放,且降低了离子释放速度,涂层具有良好的生理稳定性.抗菌实验表明复合涂层对大肠杆菌和金黄色葡萄球菌抗菌率达到99%以上,抗菌能力强.