A novel open-tubular capillary electrochromatography with magnetic nanoparticle coating as stationary phase

A novel open‐tubular capillary electrochromatography (OT‐CEC) with modified core/shell magnetic nanoparticles coating as stationary phase was introduced using external magnetic force to fix magnetic nanoparticles. The magnetic nanoparticles coating inside the capillary columns could be easily regenerated by removing and re‐applying the external magnetic field. Magnetic field intensity, concentration and flow rate of nanoparticles suspension were investigated to achieve simple and stable preparation. Mixture of five organic acids was used as the marker sample to evaluate the OT‐CEC system, and the relative column efficiency of anthranilic acid reaches 220 000 plates/m. The excellent within‐column and between‐column repeatability has been testified with the RSDs of retention time of less than 1.51 and 5.29%, respectively. The aqueous extract of rhizoma gastrodiae was analyzed by the OT‐CEC system, and 23 peaks were eluted in 30 min. Compared with conventional open‐tubular capillary column, this new system shows faster separation speed and higher column efficiency from the larger surface area of nanoparticles. It has great potential in the method development for the analysis of complex samples, since magnetic coating can effectively prolong the column life by expediently replacing stationary phase to eliminate the pollution or irreversible adsorption.     

Steady State Thermodynamics

The present paper reports our attempt to search for a new universal framework in nonequilibrium physics. We propose a thermodynamic formalism that is expected to apply to a large class of nonequilibrium steady states including a heat conducting fluid, a sheared fluid, and an electrically conducting fluid. We call our theory steady state thermodynamics (SST) after Oono and Paniconi's original proposal. The construction of SST is based on a careful examination of how the basic notions in thermodynamics should be modified in nonequilibrium steady states. We define all thermodynamic quantities through operational procedures which can be (in principle) realized experimentally. Based on SST thus constructed, we make some nontrivial predictions, including an extension of Einstein's formula on density fluctuation, an extension of the minimum work principle, the existence of a new osmotic pressure of a purely nonequilibrium origin, and a shift of coexistence temperature. All these predictions may be checked experimentally to test SST for its quantitative validity.     

Chemical states of nitrogen in ZnO studied by near-edge X-ray absorption fine structure and core-level photoemission spectroscopies

Interaction of low-energy nitrogen ions with ZnO surface has been studied by photoemission spectroscopy (PES) around N 1s core-level and near-edge X-ray absorption fine structure (NEXAFS) around N K-edge. Nitrogen can break Zn-O bonds at the surface and form N-O, Zn-N or Zn-N-O bonds, characterised by specific chemical shifts in PES or absorption peaks in NEXAFS. A distinctive signal from molecular nitrogen has also been observed in ion-bombarded samples in both NEXAFS and PES.     

Synthesis and degradation profile of cast films of PPG-DMPA-IPDI aqueous polyurethane dispersions based on selective catalysts

Waterborne polyurethane (WBU) dispersions synthesized from poly(propylene glycol) (PPG), dimethylolpropionic acid (DMPA), and isophorone diisocyanate (IPDI) with catalysts of different selectivity were prepared via by the conventional prepolymer isocyanate process. Two types of chain extenders were used, ethylene glycol (EG) and propylene glycol (PG), producing polyurethanes. The dispersions were neutralized by the addition of triethylamine. The thermal stability of the materials, obtained as cast films prepared from aqueous dispersions was evaluated by thermogravimetry (TG). It was observed that initial degradation temperatures were above 140 °C, with two-step degradation profiles. The use of a more selective catalyst in the formulations led to materials with higher thermal stability. DTG curves exhibited stages not perceptible in the curves of weight loss, which were mainly influenced by the differences in the formulations. Thermal decomposition of the obtained polyurethanes was followed by TG coupled with FTIR spectroscopy.     

利用ICP法测定ZnMgO薄膜的Mg组分

利用电感耦合等离子体(ICP)装置对分子束外延(MBE)法在Sapphire衬底上生长的Zn_1-xMg_xO薄膜的Mg组分进行了测试. 经理论分析，得到使用1次和2次检量式所确定的Zn_1-xMg_xO薄膜中的Mg组分的差异. 将采用1次检量式的ICP测定与EPMA测定结果进行对照，表明当Mg组分x≤0.5时二者的测试结果相当一致，由此证明ICP测试结果的正确性. 关键词： ZnMgO薄膜 Mg组分 分子束外延(MBE) 电感耦合等离子体(ICP)     

Composition of Satureja kitaibelii essential oil and its antimicrobial activity

The composition of the essential oil obtained by hydrodistillation from the aerial parts of Satureja kitaibelii from Rtanj mountain (Serbia), collected during three years, was studied. Thirty-nine components were identified in each sample of S. kitaibelii essential oil, representing about 87% of the oils. p-Cymene was the most dominant compound in all three oils (27.9%, 14.7% and 24.4%, respectively). The simple formulation of a lozenge with 0.2% of S. kitaibelii essential oil was prepared and the antimicrobial activity of the essential oil and the lozenge with essential oil was tested using a broth microdilution assay. Both essential oil and lozenge possessed strong antimicrobial activity with MIC values of 0.10-25 microg/mL, and 0.97-15.6 mg/mL, respectively.     

Identification of geometrical models of interface evolution for dendritic crystal growth

This Letter introduces a method for identifying geometrical models of interface evolution, directly from experimental imaging data. These local growth models relate normal growth velocity to curvature and its derivatives estimated along the growing interface. Such models can reproduce many qualitative features of dendritic crystal growth as well as predict quantitatively its early stages of evolution. Numerical simulations and experimental crystal growth data are used to demonstrate the applicability of this approach.     

Nickel-Catalyzed Amination of (Hetero)aryl Halides Facilitated by a Catalytic Pyridinium Additive

An efficient and operationally simple Ni-catalyzed amination protocol has been developed. This methodology features a simple Ni^II salt, an organic base and catalytic amounts of both a pyridinium additive and Zn metal. A diverse number of (hetero)aryl halides were coupled successfully with primary and secondary alkyl amines, and anilines in good to excellent yields. Similarly, benzophenone imine gave the corresponding N-arylation product in an excellent yield.