敏感性水凝胶及其应用研究进展

本文论述了各类敏感性水凝胶的发展历史和目前研究状况以及它们的应用研究进展,同时也对影响敏感性的凝胶结构因素和有关水凝胶敏感性相转变的物理解释作了简单介绍。     

Y2O3薄膜处理对3Cr25Ni7N合金的抗高温氧化性能的影响

采用电沉积-热解法在3Cr25Ni7N合金表面制备了Y2O3薄膜,并研究了薄膜处理对合金在1000℃空气中的抗高温氧化性能的影响。氧化动力学曲线、SEM及XRD分析结果表明,Y2O3薄膜处理使合金表面氧化膜以尖晶石结构为主,氧化膜致密,有效地抑制了Cr2O3的挥发反应,且氧化膜与基体的附着性好,因此合金在高温下的抗氧化性能得到提高,这与氧化钇薄膜在较低温度下抗高温氧化性能提高的机制是不同的。在不同温度下,Y2O3薄膜处理均可以有效提高合金的抗高温氧化性能。     

Parameterization of peptide 13C carbonyl chemical shielding anisotropy in molecular dynamics simulations.

NMR chemical shielding anisotropy (CSA) relaxation is an important tool in the study of dynamical processes in proteins and nucleic acids in solution. Herein, we investigate how dynamical variations in local geometry affect the chemical shielding anisotropy relaxation of the carbonyl carbon nucleus, using the following protocol: 1) Using density functional theory, the carbonyl (13)C' CSA is computed for 103 conformations of the model peptide group N-methylacetamide (NMA). 2) The variations in computed (13)C' CSA parameters are fitted against quadratic hypersurfaces containing cross terms between the variables. 3) The predictive quality of the CSA hypersurfaces is validated by comparing the predicted and de novo calculated (13)C' CSAs for 20 molecular dynamics snapshots. 4) The CSA fluctuations and their autocorrelation and cross correlation functions due to bond-length and bond-angle distortions are predicted for a chemistry Harvard molecular mechanics (CHARMM) molecular dynamics trajectory of Ca(2+)-saturated calmodulin and GB3 from the hypersurfaces, as well as for a molecular dynamics (MD) simulation of an NMA trimer using a quantum mechanically correct forcefield. We find that the fluctuations can be represented by a 0.93 scaling factor of the CSA tensor for both R(1) and R(2) relaxations for residues in helix, coil, and sheet alike. This result is important, as it establishes that (13)C' relaxation is a valid tool for measurement of interesting dynamical events in proteins.     

Structure-property modelling of complex formation of strontium with organic ligands in water

The method of substructural molecular fragments based on representation of the molecular graph by ensembles of fragments and involving calculations of those contributions to the given property is applied to the modelling of stability constants of the complexes of strontium(II) with organic ligands in water. Reliability of predictions of developed structure-property models was examined using three different test sets of structurally diverse ligands. The obtained models have been used for generation and screening of combinatorial library of virtual ligands. Some hypothetical efficient Sr(II) binders were suggested.     

Determination of L-Dopa and L-Dopamine in Aqueous Solutions Using In-Loop SPME Coupled with LC

A new in-loop solid-phase microextraction (in-loop-SPME) technique, based on an aluminum capillary tube coupled to HPLC, is described for on-line isolation, concentration, and analysis of analytes from aqueous samples. L-Dopa and L-dopamine, in aqueous solutions, were selected as model compounds. The main conditions affecting extraction of the analytes from aqueous samples, desorption, injection, and chromatographic separation were investigated. The method is simple and reproducible. Using the proposed method, reliable determination of L-dopa and L-dopamine at parts-per-billion concentrations was achieved. The calibration plots were linear in the range of 2.5–1500 ng mL⁻¹ with correlation coefficients of 0.999 and 0.998 for L-dopa and L-dopamine, respectively. The detection limits were 0.5–1 ng mL⁻¹ with a relative standard deviation less than 4.1%. Concentration factors more than 100-fold were obtained for these compounds.     

提升教学魅力,打造一门好课——《材料表面与界面》教学改革探索

《材料表面与界面》为高分子材料与工程专业复合材料方向的限选课。本课程对于学生奠定学科基础、培养学生对复合材料方向的兴趣具有重要的先导作用。笔者以"提升教学魅力,打造一门好课"为改革目标,充分贯彻了"教学内容是教学魅力的根本,教学方法与教学手段是将教学内容高效转化为教学魅力的催化剂"这一指导思想,从教学内容与教学方式两方面进行改革。从教学反馈看,这些改革措施能够改善教学效果,提高学生学习效率,得到了学生的认可。     

Visible Up-Conversion Luminescence in Ho3+: BaTiO3 Nano-Crystals Prepared by Sol Gel Technique

Visible up-conversion emissions at (435, 545, 580, 675 and 690 nm) and (437, 547 575 and 675 nm) have been observed from the sol-gel derived nano-crystalline Ho³⁺: BaTiO₃ powders and thin films respectively, under 808 nm laser diode excitation emissions. Combined with the energy level structure of Ho³⁺ ions and the kinetics of the visible emissions, the up-conversion mechanism has been analyzed and explained. The blue, green and red emissions of both samples has been attributed to the ground state-directed transition from (⁵F₁), (⁵S₂) and (⁵F₅), which are populated through excited state absorption (ESA) for 808 nm excitation. Nano-structure pure barium titanate and doped with different concentrations of Ho³⁺ ions in the from of powder and thin film have been prepared by sol-gel technique, using barium acetate (Ba(Ac)₂), and titanium butoxide (Ti(C₄H₉O)₄), as precursors. The thin films were prepared by sol-gel spin coating method. The as-grown thin films and powders were found to be amorphous, which crystallized to the tetragonal phase after heating at 750°C in air for 30 minutes. The crystallite sizes of the thin film and powder both doped with 4% Ho³⁺ ions was found to be equal to 11 and 16 nm, respectvely.     

Kinetic studies of nickel speciation in model solutions of a well-characterized humic acid using the competing ligand exchange method

Publications on the binding characteristics of metals with humic acid (HA) are sparse. Here we investigated the release of nickel from Ni(II)-HA complexes using model solutions of three different [Ni(II)]/[HA] mole ratios at three different pH values; we also compared the results with those of [Ni(II)]/[FA] complexes from previous work in this laboratory. Ligand exchange kinetics using the competing ligand exchange method (CLEM) were studied using two different techniques: graphite furnace atomic absorption spectrometry (GFAAS) with Chelex 100 resin as the competing ligand, and adsorptive cathodic stripping voltammetry (AdCSV) with dimethylglyoxime as the competing ligand to measure the rate of dissociation of Ni(II)-HA complexes. The results of the kinetic studies showed that as the [Ni(II)]/[HA] mole ratio was decreased, the rate of dissociation of Ni(II)-HA complexes decreased, and the proportion of free Ni²⁺ ions plus very labile nickel complexes decreased while the proportion of the less labile kinetically distinguishable components increased. Generally, the rate of dissociation of Ni(II)-HA complexes was slower than that of Ni(II)-FA complexes. Studies on the validity of the kinetic model showed that the concentrations of chemical species varied in a reasonable way with pH and the [Ni(II)]/[HA] mole ratios, indicating that the kinetically distinguishable components have chemical significance and the kinetic model is valid.     

C(2×2)S/Fe(001)吸附体系的SCF-Xa-MS研究

采用SCF-X_α-MS方法, 对于C(2×2)S/Fe(001)吸附体系, 选择Fe_5S和Fe_9S两种原子簇模型, 研究了该吸附体系的电子结构、吸附成键特征及其相互作用图象。结果表明, S吸附于Fe(001)单晶表面具有较强的定域性质, S原子与底物Fe原子之间的吸附相互作用主要表现为S(3p)-Fe(4s,3d)之间的轨道相互作用。通过对表面吸附键长的优化, 其结果与X.S.Zhang等的ARPEFS的实验结果一致。     

Trace analysis of selected benzidine and diaminodiphenylmethane derivates in urine by means of liquid chromatography using precolumn sample preconcentration,UV and electrochemical detection

Summary For the title compounds 4,4-DADPM, MOCA, 3,3-DCB, 4-ADP and 4-ADPA listing on the EPA priority pollutant list, an analytical practicable, reliable, reproducible and sensitive procedure is required. Therefore a new method has been developed for the routine determination of these toxic aromatic amines in urine at the ppb level. The quantitative determination of amines is a suitable procedure of occupationally exposed persons. Urine sample preparation is done using simple liquid-liquid extraction followed by a precolumn enrichment (PRP₁-material; Hamilton). Breakthrough measurements were done using an enrichment column packed with PRP₁ material. The capacities of the studied amines ranged from 21.9mg/g to 96.6mg/g, while influent concentrations differed from 28.3mg/l to 332.0mg/l. The advantages of electrochemical detection regarding to selectivity and sensitivity are clearly indicated in this paper. Separation has been achieved applying reversed-phase-high-performance-liquid chromatography (LiChrosorb RP 18/5m) followed by electrochemical or UV-detection. The detection limits employing an electrochemical detector at a potential of 1 V range from 2.2ng to 12.1ng. UV detection at 254 nm and 280 nm is about 10–100 times less sensitive. Recoveries from spiked water samples at the 5ppb levels were 75% to 96% respectively. The standard deviation of the developed procedure varies from 5.3% to 14%. Day-to-day repeatability is good.