酶催化光度法测定异丙肾上腺素

试验表明:在pH 9.5氨水-氯化铵缓冲介质中,牛血红蛋白对过氧化氢与酸性络蓝K的氧化还原反应的催化作用因异丙肾上腺素的存在而被抑制,而且其抑制率与异丙肾上腺素的浓度在8.1×10~(-8)～1.2×10~(-5)mol·L~(-1)范围内呈线性关系,其检出限(3S/N)为2.2×10~(-9)mol·L~(-1)。据此,提出了一种简单而灵敏的测定异丙肾上腺素的酶催化光度法。此方法已用于盐酸异丙肾上腺素注射液中异丙肾上腺素含量的测定,并以此样品为基体用标准加入法作回收试验,测得回收率在92.8%～105.4%之间,测定值的相对标准偏差(n=5)在2.6%～5.8%之间。     

钴(Ⅱ)、锰(Ⅱ)与4-吡啶甲醛缩4-氨基安替比林配合物的合成、晶体结构与磁性

以希夫碱衍生物4-氨基安替比林缩吡啶-4-甲醛为配体(L),采用溶剂热合成法,成功合成了2个Schiff碱Co(Ⅱ)配合物[CoLCl₂](1)、Mn(Ⅱ)配合物[MnLCl₂](2),通过元素分析、红外光谱IR、XRD、TG和磁性分析等测试手段对2个配合物进行表征,并用X-射线单晶衍射测得Co(Ⅱ)、Mn(Ⅱ)配合物的晶体结构。单晶结构表明,配合物1的晶体属于单斜晶系,空间群为Cc;配合物2的晶体属于三斜晶系,空间群为P1。配合物1是以Co(Ⅱ)为中心的扭曲四面体构型,配合物2是以Mn(Ⅱ)为中心的扭曲八面体构型。     

Effect of Plasma Treatment on the Structures and Properties of Konjac Glucomannan Film

To understand the effect of plasma treatment on the Konjac glucomannan film, the nitrogen plasma was injected into the film by ion beam injection machine in this study. The structures and properties of Konjac glucomannan film after plasma treatment were analyzed by Infrared spectroscopy, Raman spectrum, X-ray, ect. The result showed that nitrogen groups appeared in the KGM molecular chain and part of this chain fractured, and the number of hydrogen bonds increased after the treatment of plasma. The form of KGM molecule remained amorphous non-crystalline state, but the crystalline region was increased and became more ordered. The mechanical property of tensile strength and breaking elongation was improved, while the WVP was decreased. The nitrogen groups were grafted on the KGM molecular chain after plasma treatment, which led to the improvement of the properties of KGM film.     

气体在纳孔分子材料中吸附的理论模拟研究进展

纳孔分子材料是由孤立分子通过非共价相互作用堆积形成的具有纳微孔道结构的材料.和传统共价网络孔材料相比,纳孔分子材料具有独特的溶解性,并兼具气体存储与分离,限域反应和催化等方面的潜在应用,已成为当前研究的新热点.通过着眼于新型纳孔分子材料的设计,对相关理论研究进行了综合评述,主要包括以下3个方面:(1)无论是气体吸附还是催化反应,纳孔分子材料的晶体结构预测都是先决条件,只有在纳孔分子材料的晶体结构得到准确预测的前提下,才能够定向、准确、系统地对其进行设计;(2)气体在纳孔分子材料中吸附的分子动力学研究有助于深刻理解气体吸附的微观传输扩散机制;(3)气体在纳孔分子材料中吸附的巨正则蒙特卡洛模拟有利于对设计材料的吸附性能进行直接预测,得到可以直接与实验吸附量、吸附热等信息进行比较的结果.最后,简述了理论设计新型纳孔分子材料存在的问题以及未来发展前景.     

沉淀剂对悬浮共沉淀法制备二甲醚催化剂的影响

以无水乙醇为溶剂,将Cu、Zn和Al的硝酸盐并流共沉淀在HZSM-5分子筛的悬浮溶液中,一步合成CuO-ZnO-Al2O3/HZSM-5双功能催化剂.研究了沉淀剂的种类、加入顺序和加入量对催化剂活性的影响.结果表明,以适量的草酸作沉淀剂,采用悬浮液并流共沉淀法制备的双功能催化剂,对CO2加氢直接合成二甲醚有较高的催化性能:在固定床反应器中,温度为270℃,压力为3.0 MPa,空速为4 800 h-1的反应条件下,CO2的单程转化率达到28.7%,二甲醚的选择性达到53.2%.BET、XRD、TPR、TPD和N2O滴定等对催化剂结构表征结果表明,双功能复合催化剂CuO-ZnO-Al2O3/HZSM-5的结构影响CO2加氢合成二甲醚的催化性能.     

乙烯齐聚制α-烯烃反应体系的热力学研究

利用Benson基团贡献法计算了乙烯齐聚制α-烯烃反应各物质的标准摩尔生成焓、标准摩尔熵和摩尔定压热容,在298～700 K温度范围内对乙烯齐聚制α-烯烃反应体系的反应热、吉布斯自由能以及反应平衡常数进行了详尽的计算,分析了不同反应步骤的热力学平衡与限度,对不同反应发生的热力学可能性与顺序进行了判断,考察了反应温度和压力对乙烯齐聚制α-烯烃反应化学平衡的影响,确定了乙烯齐聚制α-烯烃反应体系适宜的工艺条件.结果表明:乙烯齐聚制α-烯烃反应为放热反应;从热力学上看,温度低于546 K时,乙烯齐聚生成直链α-烯烃反应为自发过程,且比α-烯烃异构化和烯烃歧化反应更容易进行;低温、高压有利于乙烯齐聚制α-烯烃反应的进行;乙烯齐聚制α-烯烃反应体系适宜的工艺条件为温度323～473 K,压力5～20 MPa,且在SHOP法的工艺条件下(温度363 K,压力10.3 MPa),乙烯齐聚生成直链α-烯烃反应的热力学平衡转化率接近于100%.     

Esterification of Oleic Acid to Produce Biodiesel over 12-Tungstophosphoric Acid Anchored Two-dimensional Zeolite

Biodiesel has emerged as a non-toxic, biodegradable, and renewable fuel substitute that can be readily produced via the esterification reaction of free fatty acids. The present work explores the potential of 12-tungstophosphoric acid(TPA) anchored two-dimensional(2D) ITQ-2 zeolite(TPA/ITQ-2) as heterogeneous acid catalysts for biodiesel production. TPA/ITQ-2 material was prepared by swelling, delamination, and subsequent wetness incipient impregnation approach. The prepared catalysts were comprehensively characterized by powder X-ray diffraction, N₂ adsorption/desorption, temperature-programmed desorption of ammonia, flou-rier transform infrared spectroscopy, and transmission electron microscopy. The catalytic activity of TPA/ITQ-2 for biodiesel production was evaluated by the esterification reaction of oleate acid with methanol. Process parameters, such as reactant molar ratio and TPA loading were optimized. Due to the superior mass transfer and adequate stable acid sites, 2D TPA/ITQ-2 showed a higher catalytic activity and a better recyclable stability than the 3D and layered TPA/zeolites. This work will provide new opportunities for the design of 2D zeolite-based acid catalysts for biodiesel production.     

SNR phase order k-space encoding (SPOKE)

A method of determining the phase-encode order for MR Fourier-encoded imaging is described, which provides an additional option for optimizing images from samples with signals that change during data acquisition. Examples are in hyperpolarized helium gas imaging of the lungs where polarization is lost with each RF pulse or the signal changes observed in rapid dynamic studies with T₁ or T₂* contrast agents when mixing is taking place. The method uses a single frequency-encoded projection in the proposed phase-encoding direction. The projection is subsequently sorted into signal-to-noise ratio (SNR) order. The indices of the sorted array are then used to create the phase-encode table to be used for the scan. This phase table is sorted in descending SNR order for signals that decrease during data acquisition and in ascending order for signals that increase during data acquisition. Simulations suggest that this technique can produce higher resolution than centric-ordered phase encoding at the expense of increased modulation (ghosting) artifact for dynamically changing signals. Initial practical implementation of the technique has been carried out on a dedicated 0.2-T Niche MR system, and the test object results agree well with simulations. Hyperpolarized 3-He lung images have also been acquired and postprocessed using the SNR phase order k-space encoding (SPOKE) methodology and show potential for improved imaging with high flip angles where polarization is rapidly lost. Applications may also be found for 3D volumetric acquisitions where two dimensions can be SPOKE encoded.     

单一基质白光荧光粉Na3Sc2(PO4)3∶Tm3+,Dy3+的合成及发光性质

采用高温固相法成功制备了Na₃Sc_2-x-y(PO₄)₃∶xTm³⁺,yDy³⁺荧光粉,利用X射线衍射仪、扫描电子显微镜和荧光光谱仪对荧光粉进行了物相、形貌和发光性能进行了表征。 在Na₃Sc₂(PO₄)₃∶0.06Tm³⁺,yDy³⁺荧光粉中,物质的量分数6%的Tm³⁺和6%的Dy³⁺在360 nm激发下呈现出白光发射,其发射光谱在460~685 nm范围内存在Tm³⁺位于457 nm的特征发射峰,对应于Tm³⁺的³H₆→¹D₂跃迁,以及Dy³⁺位于483、577和672 nm处的3个特征发射峰,分别对应于Dy³⁺的⁴F_9/2→⁶H_15/2、⁴F_9/2→⁶H_13/2和⁴F_9/2→⁶H_11/2的跃迁。 观测到Na₃Sc₂(PO₄)₃∶Tm³⁺荧光粉的发射光谱与Na₃Sc₂(PO₄)₃∶Dy³⁺的激发光谱有较好的重叠,且Tm³⁺的荧光寿命随Dy³⁺浓度的增加逐渐降低,因此在Na₃Sc₂(PO₄)₃∶Tm³⁺,Dy³⁺荧光粉中存在Tm³⁺向Dy³⁺的能量传递。 利用Dexter和Reisfeld近似分析了能量转移机制,发现从Tm³⁺到Dy³⁺的能量传递临界距离为1.6 nm,能量传递过程是通过偶极-偶极相互作用进行的。 Na₃Sc₂(PO₄)₃∶0.06Tm³⁺,0.06Dy³⁺荧光粉具有较好的耐受热猝灭性能,在423、473和523 K时的发射强度分别为298 K时发射强度的97.6%、89.2%和78.6%。 随着Dy³⁺浓度的增加,Na₃Sc₂(PO₄)₃∶0.06Tm³⁺,yDy³⁺荧光粉的发光颜色由蓝色转变为白色,再由白色变黄色。 Na₃Sc₂(PO₄)₃∶Tm³⁺,Dy³⁺荧光粉作为一种可调色或单相白光荧光粉在发光二极管上具有潜在的应用前景。