Protein separation using a novel silica-based RPLC/IEC stationary phase modified with N-methylimidazolium ionic liquid

Ionic liquids (ILs) immobilized on silica as novel high performance liquid chromatography (HPLC) stationary phases have attracted considerable attention. However, it has not been applied to protein separation. In this paper, N-methylimidazolium IL-modified silica-based stationary phase (SilprMim) was prepared and investigated as a novel multi-interaction stationary phase charged positively for protein separation. The results indicate that all of the basic proteins tested cannot be absorbed on this novel stationary phase, whereas all of the acidic proteins tested can be retained, and the baseline separation of eight kinds of acidic protein standards can be achieved when performed in reversed phase/ ion-exchange chromatography (RPLC/IEC) mode. Compared with commonly used commercial octadecylated silica (ODS) column, the novel stationary phase can show selectivity and good resolution to acidic proteins, which has a promising application in the separation and analyses of acidic proteins from the complex samples in proteomics. In addition, the chromatographic behavior of proteins, the effect of the ligand structure and the retention mechanism on this stationary phase were also investigated.     

Influence of tailored CuO and Al/CuO nanothermites on the thermocatalytic degradation of nitrocellulose and combustion performance of AP/HTPB composite propellant

Cellulose - Al/CuO nanothermites have displayed unique catalytic activities in accelerating the thermolysis of nitrocellulose (NC) and combustion characteristics of AP/HTPB propellant depending on...     

Rational Design of Highly Efficient One-pot Synthesis of Ternary PtNiCo/FTO Nanocatalyst for Hydroquinone and Catechol Sensing

In this work, we present a simple and efficient method for preparation of widely dispersed PtNiCo nanocatalyst on FTO without the use of any heavy complex structure. The proposed nanocatalyst enhances the chemical interaction of PtNiCo/FTO and increases its catalytic activity, which was used for electrochemical sensing of catechol and hydroquinone. The surface morphology was characterized by TEM, HRTEM, and XRD. The size of the PtNiCo/FTO octahedrons nanocatalyst was about 0.35–4 nm. Gradual increase of concentration exhibited linearity in oxidation peak response up to 1100 μM with a low detection limit of 0.79 μM for HQ and 1.05 μM for CC. The sensitivity is 1035 μAmM⁻¹ cm⁻² for catechol and 1197 μAmM⁻¹ cm⁻² for hydroquinone. The prepared nanomaterial/sensor applied to real water samples with good reproducibility (98–99 %).     

多羟基化合物键合亲水色谱固定相的制备及其分离性能

用硅胶与氨丙基三甲氧基硅烷反应,再与δ-葡萄糖酸内酯反应,制备了一种多羟基化合物键合的新型亲水色谱固定相。以水-有机溶剂(乙醇、乙腈、四氢呋喃)为流动相,通过改变流动相中有机溶剂的种类及浓度、缓冲盐浓度和柱温,考察了该固定相对6种强极性中药组分的保留行为和保留机理。当水的比例在0～40%(v/v)范围时,溶质的保留随着流动相中水的比例的增大而减小,属于典型的亲水色谱分离模式;而当流动相中水的比例在0～100%(v/v)范围内变化时,溶质的保留随着水的比例变化呈“U”形曲线,属于亲水色谱和反相色谱的混合保留机理。缓冲盐的浓度和pH效应说明,所选用的中药组分与所制备的固定相间还存在弱的静电作用。该固定相对6种中药组分以及丹参注射液具有良好的分离性能,表明其在强极性中药有效成分的分离及其他强极性物质的分离分析中具有一定的应用前景。     

The phonon-assisted photon-drag effect in a two-dimensional semiconductor quantum-well structure

The phonon-assisted photon-drag effect in a two-dimensional semiconductor quantum well structure is investigated. By making use of second-order perturbation theory and the classical Boltzmann equation we found, by considering both intrasubband and the intersubband electronic transitions, that the electric field generated by the photon-drag effect in a typical GaAs–AlGaAs two-dimensional system is enhanced by almost one order of magnitude as compared with that of a bulk system. Moreover, the results can qualitatively account for the observed absorption spectra due to intersubband electronic transitions occurring in GaAs quantum wells.     

Self-assembly of cavitand tetracarboxylic acid: highly porous packing structure of one-dimensional hydrogen-bonded network

When recrystallized from DMF and p-xylene, cavitand tetracarboxylic acid 1 self-assembles into a wave-ladder type of one-dimensional hydrogen-bonded network. The three-dimensional packing structure consists of huge chambers, each of which is filled with one molecule of p-xylene and five molecules of DMF.     

Near-saturation (P,ρ,T) and vapor-pressure measurements of NH3, and liquid-phase isothermal (P,ρ,T) and bubble-point-pressure measurements of NH3+H2O mixtures

Near-saturation pressure, density, and temperature (P,ρ,T) and vapor-pressure measurements for NH₃ are reported over a temperature range from 279 to 392 K. Liquid-phase isothermal (P,ρ,T) and bubble-point-pressure measurements for two standard mixtures of NH₃+H₂O (x_NH3=0.8360 and 0.9057 mole fraction) are reported over a temperature range from 280 to 379 K and at pressures to 7.7 MPa. These data are compared to literature data and correlations and agree within ±3% for bubble-point pressures, ±0.005 g/cm³ for liquid densities, and ±0.0011 g/cm³ for vapor densities. A consistent data set for equation-of-state optimization at high concentrations of NH₃ is proposed.     

Ru(II)-catalyzed asymmetric cyclopropanation using chiral diphenylphosphino(oxazolinyl)quinoline ligands

Several chiral 8-diphenylphosphino-2-oxazolinylquinolines were synthesized starting from 2-cyano-8-hydroxyquinoline. These N,N,P-chelates were successfully employed in the Ru(II)-catalyzed asymmetric cyclopropanation reactions of diazo-alkenes. The catalytic system exhibited good reactivity and high thermal stability and provided high yields in the intramolecular cyclopropanation, albeit somewhat decreased enantioselectivities compared to known catalytic systems. A dramatic dependency of the enantioselectivity on the substituents of the oxazoline ring was observed.     

1,3-butadiene telomerization with methanol catalyzed by heterogenized palladium complexes

The heterogenization of palladium complexes on silica as well as on functionalized styrene/divinylbenzene crosslinked resins and linear poly(styrene) is described. In particular, palladium (0) and palladium (II) derivatives were anchored to the above polymeric systems through their functionalization with bidentate ligands such as acetylacetonate and 1,3-bis(diphenylphosphino)propane moieties. The resulting heterogenized complexes were checked in the catalytic telomerization of 1,3-butadiene with methanol. Their performances were studied in terms of activity and selectivity to telomers. Whereas the heterogenization of palladium complexes either on silica or on polymer resins via the acetylacetonate ligand resulted labile during the catalytic cycle, the polymer-bound palladium complexes via the diphosphine ligand, when activated by an alkoxide, displayed activity and selectivity comparable with those of the corresponding homogeneous counterparts, without appreciable metal leaching in solution.     

动力学因素对液相色谱分离整体蛋白的影响

依据液相色谱分离整体蛋白的效果与色谱柱柱长基本无关的事实,研究了动力学因素对疏水相互作用色谱(HIC)分离整体蛋白的影响。首次提出了用于线性梯度洗脱条件下蛋白分离的“条件板高”(H)概念,并将其用于动力学因素对分离整体蛋白的影响的表征。分别用常用的色谱柱和色谱饼对标准蛋白进行了分离,绘制了类似于van Deemter的“条件板高”对流动相线速(u)的曲线图。发现对应于色谱柱最低“条件板高”的适合线速约为色谱饼的1/5～1/15,且色谱饼的适合线速范围也较色谱柱宽得多。据此,用装填有HIC填料的色谱饼(10 mm×20 mm i.d.)在12 min内便可完全分离7种标准蛋白。还用装填有HIC填料的色谱饼对重组人粒细胞集落刺激因子(rhG-CSF)进行了复性并同时纯化,在50 min内,仅用一步色谱法就可获得纯度≥97%的rhG-CSF,其质量回收率为39%,比活＞1×108 IU/mg。可以预计,装填极细颗粒的刚性色谱填料的色谱饼可在高负荷条件下进行整体蛋白的高速和高分离度的分离、纯化并同时复性,达到“三高”。