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141.
Anne Tscheliessnig Danny Ong Jeremy Lee Siqi Pan Gernalia Satianegara Kornelia Schriebl Andre Choo Alois Jungbauer 《Journal of chromatography. A》2009,1216(45):7851-7864
A two-step purification strategy comprising of polyethylene glycol (PEG) precipitation and anion-exchange chromatography was developed for a panel of monoclonal immunoglobulin M (IgM) (pI 5.5–7.7) produced from hybridoma cultures. PEG precipitation was optimized with regards to concentration, pH and mixing. For anion-exchange chromatography, different resins were screened of which Fractogel EMD, a polymer grafted porous resin had the highest capacity. Despite its significantly slower mass transfer, the binding capacity was still higher compared to a convection driven resin (monolith). This purification strategy was successfully demonstrated for all 9 IgMs in the panel. In small scale most antibodies could be purified to >95% purity with the exception of two which gave a lower final purity (46% and 85%). The yield was dependent on the different antibodies ranging from 28% to 84%. Further improvement of recovery and purity was obtained by the digestion of DNA present in the hybridoma supernatant using an endonuclease, benzonase. So far this strategy has been applied for the purification of up to 2 l hybridoma supernatants. 相似文献
142.
嵌段共聚物在乳液聚合和分散聚合中的应用 总被引:4,自引:0,他引:4
综述了嵌段共聚物在乳液聚合和分散聚合中作为稳定剂应用的进展,主要讨论了共聚物化学组成,比例,分子量,浓度以及胶束形成等因素对聚合体系的影响。 相似文献
143.
P. M. Carreira D. Nunes P. Valério M. F. Araújo 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(1):153-156
The Nuclear and Technological Institute (Instituto Tecnológico e Nuclear—ITN) in cooperation with the International Atomic
Energy Agency (IAEA) has been conducting a nationwide survey of hydrogen (2H/1H) and oxygen (18O/16O) isotopic composition of monthly precipitation since 1988. This paper focuses on basic features of spatial and temporal
distribution of δ18O and δ2H in the precipitation over Continental Portugal derived from ITN database. Phenomenological relationships between stable
isotopes composition of precipitation and various climate-related parameters (local air temperature, distance to the Atlantic
coast, altitude, amount of precipitation) are established and discussed. 相似文献
144.
Vitalii S. Tkach Dmitrii S. Suslov Gennadii V. Ratovskii Tuczek Felix 《Journal of organometallic chemistry》2008,693(12):2069-2073
A series of palladium complexes of general formula [(Acac)PdL1L2]+A−, where L1, L2 = phosphines and A = BF4, CF3SO3, were synthesized. Preliminary studies show that the complexes are active in selective dimerization of styrene and addition polymerization of norbornene. 相似文献
145.
Nitroxide-mediated solution and precipitation polymerizations of styrene in toluene and supercritical carbon dioxide (scCO2), respectively, using the nitroxides N-tert-butyl-N-[1-diethylphosphono-(2,2-dimethylpropyl)]nitroxide (SG1) and 2,2,5-trimethyl-4-phenyl-3-azahexane-3-nitroxide (TIPNO) are presented. Solution polymerizations are compared with simulations using PREDICI software, revealing that differences in the polymerization behaviours between the SG1- and TIPNO-mediated systems cannot be rationalized based on literature rate coefficients and the ideal mechanism for nitroxide-mediated polymerization. Nitroxide and monomer partitioning between the polymer particles and the continuous phase play important roles in the precipitation polymerizations in scCO2. Loss of control (broader molecular weight distributions) as a result of nitroxide partitioning is accentuated at low monomer loading, and is significantly more pronounced for TIPNO than SG1. However, at higher monomer loading the level of control was superior in scCO2 compared to in the corresponding solution polymerizations for both nitroxides, most likely caused by an increase in the number of activation-deactivation cycles experienced by any given chain during its growth. 相似文献
146.
本体聚合反应过程中聚甲基丙烯酸甲酯增长自由基的ESR研究 总被引:3,自引:0,他引:3
采用TM110谐振腔和φ2mm样品管,在17℃室温条件下成功地记录了MMA本体聚合反应过程中增长自由基的ESR谱。当把DMA加入到MMA和BPO中后,立即抽取0.17ml混合液到φ2mm样品管并记谱。以后每隔2分钟记谱一次,波谱从13(5+8)条线逐渐变成9(5+4)条线。我们用阻碍振荡模型和构象重叠模型作了模拟。从全部谱图看,前者似更合理些。ESR实验表明:在聚合过程前期,自由基浓度基本保持不变,但从聚合中期的某一时刻开始,浓度剧增,它正好同步地与本体聚合反应的自加速效应相对应,而且其变化规律和单体转化率相平行。最后,我们用微波功率饱和方法观测到9线谱的协同自旋跳跃所产生的卫线,证明了主导的电子自旋晶格弛豫机理来自电子一核自旋间的偶极偶合角调制。 相似文献
147.
以甲苯二异氰酸酯(TDI)为单体,在水与丙酮混合溶剂中通过沉淀聚合一步法制备了富含胺基的聚脲多孔材料(PPU),通过扫描电镜和压汞法对其表面形貌和孔结构进行了表征.PPU经戊二醛(GA)活化后用于荧光假单胞菌脂肪酶(PFL)的固定,考察了GA活化过程中GA浓度对酶固定量及固定酶活性的影响.结果表明,PPU是一种粒子尺寸分布在30~50μm范围的形状不规则的多孔粒子,孔径在2 nm~100μm之间呈连续分布.在pH=8.0的缓冲溶液中用0.17 mol/L的GA对PPU进行改性,将改性后的PPU用于PFL的固定,当酶溶液浓度为2.56 mg/m L时,得到酶的最大固定量为95.2 mg/g,固定酶的活性为375 U/mg,相对活性为76%.将此固定酶作为催化剂,用于1-苯乙醇外消旋化合物的手性拆分,并与游离酶催化的结果相比较.结果表明,固定酶的反应活性和立体选择性都明显优于游离酶.通过沉淀聚合制备的聚脲多孔材料在酶固定及手性分子拆分方面具有应用前景. 相似文献
148.
采用液相沉淀法,以硝酸铋[Bi(NO_3)_3]为添加剂来调控碳酸钙晶体的形状与大小,制备了海螺状碳酸钙粒子.通过扫描电子显微镜(SEM)、X射线衍射仪(XRD)、热重分析仪(TGA)、原子荧光光谱仪(AFS)等对产物的结构和性能进行了表征.结果表明,在60℃条件下,添加20 mL浓度为2 g/L的Bi(NO_3)_3溶液可得到海螺状球霰石型碳酸钙粒子,且其荧光性明显增强.在碳酸钙的成核过程中,Bi~(3+)的加入起到了显著的调控作用. 相似文献
149.
Iron(III) hydroxide was precipitated from the homogeneous solutions, containing variuos amounts of iron(III) nitrate, potassium sulfate, and urea, by heating at 85 °C for different periods of time (5‐30 min). The precipitated solids were either in the form of gel or dispersed particles of different shapes and sizes, depending upon the composition of the reactant mixtures. The as‐prepared solids were amorphous in nature and were formulated as Fe(OH)3.H2O. On calcinations at 800 °C for 1 h, the latter converted into crystalline compound, composed of α‐Fe2O3 (hematite). The calcined particles retained the original features of their precursors to a maximum extent. 相似文献
150.
The reaction between ZnCl2 and N,N-bis[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]-1-phenylethylamine (bdmppea) affords [(bdmppea)ZnCl2], whose structure has been determined by X-ray crystallography. The [(bdmppea)ZnEt2] complex in situ prepared by the reaction between [bdmppea] and ZnEt2 exhibited high activity toward the polymerization reaction of rac-lactide at room temperature. However, its activity decreased sharply with decreasing temperature. Stereospecificity of this catalyst characterized by heterotacticity (Pr) was determined by homonuclear decoupled NMR spectroscopy, which value was ∼0.58. 相似文献