碳原子的最大成键度

本文通过对双自由基ＨＣ＝Ｃ－ＣＨ铁ＨＭＯ分析，证明了碳原子的最大成键度可达到４．８２８。     

链霉素生产废水对斑马鱼肌肉组织SOD活性和MDA含量的影响

采用室内暴露实验方法,研究体积分数分别为0,10%,30%,50%和70%的链霉素生产废水15d内对斑马鱼肌肉组织超氧化物歧化酶(SOD)和丙二醛(MDA)含量的影响。结果显示:斑马鱼肌肉SOD活性在第3天受到显著诱导,体积分数50%实验组SOD活性达到最大值30.56U/mg。体积分数70%实验组SOD活性随着暴露时间的延长逐渐降低。体积分数30%和50%实验组MDA活性在第3天受到显著诱导,在第6天大幅度下降,降幅分别为43.04%和47.50%,第12天和第15天,MDA活性都高于对照组。暴露期间体积分数10%和70%实验组的MDA活性高于对照组。实验表明,鱼体肌肉组织SOD活性和MDA含量在暴露过程中变化明显,该链霉素生产废水已经对斑马鱼产生了氧化损伤效应。     

Vicinal diaminobenzoacridine used as the fluorescent probe for trace nitric oxide determination by flow injection spectrofluorimetry and macrophage cells imaging

Based on a photoelectron transfer (PET) mechanism, vicinal diaminobenzoacridine (VDABA), a fluorescent probe for the determination of trace amounts of nitric oxide radical in biological sample, was synthesized and characterized by elemental analysis, IR, ¹H NMR and ¹³C NMR spectrum. Combining a flow injection with spectrofluorimetry, a high-throughput method for detecting NO was obtained, which was successfully applied to the determination of NO in the human serum. The proposed method was simple, rapid, precise and automatic. Under optimum conditions, the linear calibration range was from 1.1 × 10⁻⁷ to 5.0 × 10⁻⁶ M and the detection limit was 3.1 × 10⁻⁸ M. Furthermore, the probe could make cell-derived NO “visible” by using confocal laser scanning microscope.     

An experimental study of cyclic deformation of extruded AZ61A magnesium alloy

Thin-walled tubular specimens were employed to study the cyclic deformation of extruded AZ61A magnesium alloy. Experiments were conducted under fully reversed strain-controlled tension-compression, torsion, and combined axial-torsion in ambient air. Mechanical twinning was found to significantly influence the inelastic deformation of the material. Cyclic hardening was observed at all the strain amplitudes under investigation. For tension-compression at strain amplitudes higher than 0.5%, the stress-strain hysteresis loop was asymmetric with a positive mean stress. This was associated with mechanical twinning in the compression phase and detwinning in the subsequent tension phase. Under cyclic torsion, the stress-strain hysteresis loops were symmetric although mechanical twinning was observed at high shear strain amplitudes. When the material was subjected to combined axial-torsion loading, the alternative occurrence of twinning and detwinning processes under axial stress resulted in asymmetric shear stress-shear strain hysteresis loops. Nonproportional hardening was not observed due to limited number of slip systems and the formation of mechanical twins. Microstructures after the stabilization of cyclic deformation were observed and the dominant mechanisms governing cyclic deformation were discussed. Existing cyclic plasticity models were discussed in light of their capabilities for modeling the observed cyclic deformation of the magnesium alloy.     

Adsorption and desorption behaviors of DNA with magnetic mesoporous silica nanoparticles

The interaction between DNA and mesopores is one of the basic concerns when mesoporous silica nanoparticle (MSN) is used as a DNA carrier. In this work, we have synthesized a type of mesoporous silica nanoparticle that has a Fe(3)O(4) inner core and mesoporous silica shell. This magnetic mesoporous silica nanoparticle (denoted as M-MSN) offers us a convenient platform to manipulate the DNA adsorption and desorption processes as it can be easily separated from solution by applying a magnetic field. The DNA adsorption behavior is studied as a function of time in chaotropic salt solution. The maximum amount of adsorbed DNA is determined as high as 121.6 mg/g. We have also developed a method to separate the DNA adsorbed onto the external surface and into the mesopores by simply changing temperature windows. The desorption results suggest that, within the whole adsorbed DNA molecules, about 89.5% has been taken up by M-MSN mesopores. Through the dynamic light scattering experiment, we have found that the hydrodynamic size for M-MSN with DNA in its mesopores is higher than the naked M-MSN. Finally, the preliminary result of the adsorption mechanism study suggests that the DNA adsorption into mesopores may generate more intermolecular hydrogen bonds than those formed on the external surface.     

矿山管理报表的动态网页生成方法

研究了矿山复杂报表动态网页生态方法,以可视化方式自由定制报表结构,将各种报表的结构信息存入数据库,建立起报表模板库,浏览器生成报表时,通过Active Server Pages（ASP）方法从数据库中提取报表模板,根据报表的结构生成报表。     

Study on the adsorption mechanism of DNA with mesoporous silica nanoparticles in aqueous solution

Among the numerous adsorption strategies for DNA adsorption into mesopores, the salt-solution-induced adsorption method has a great application potential in nucleic acids science; thus, it is important to understand the adsorption mechanism. This work demonstrates the mechanistic aspects underlying the adsorption behaviors of DNA with mesoporous silica nanoparticles (MSNs) in aqueous solution. The driving forces for the adsorption process can be categorized into three parts: the shielded electrostatic force, the dehydration effect, and the intermolecular hydrogen bonds. Compared to the adsorption behaviors of DNA with a solid silica nanosphere, we find some unique features for DNA adsorption into the mesopores, such as increasing the salt concentration or decreasing the pH value can promote DNA adsorption into the mesoporous silica. Further analysis indicates that the entrance of DNA into mesopores is probably controlled by the Debye length in solution and DNA can generate direct and indirect hydrogen bonds in the pores with different diameters. The following desorption study depicts that such types of hydrogen bonds result in different energy barriers for the desorption process. In summary, our study depicts the mechanism of DNA adsorption within mesopores in aqueous solution and sets the stage for formulating MSNs as carriers of nucleic acids.     

Synthesis and characterization of pore size-tunable magnetic mesoporous silica nanoparticles

Magnetic mesoporous silica nanoparticles (M-MSNs) are emerging as one of the most appealing candidates for theranostic carriers. Herein, a simple synthesis method of M-MSNs with a single Fe(3)O(4) nanocrystal core and a mesoporous shell with radially aligned pores was elaborated using tetraethyl orthosilicate (TEOS) as silica source, cationic surfactant CTAB as template, and 1,3,5-triisopropylbenzene (TMB)/decane as pore swelling agents. Due to the special localization of TMB during the synthesis process, the pore size was increased with added TMB amount within a limited range, while further employment of TMB lead to severe particle coalescence and not well-developed pore structure. On the other hand, when a proper amount of decane was jointly incorporated with limited amounts of TMB, effective pore expansion of M-MSNs similar to that of analogous mesoporous silica nanoparticles was realized. The resultant M-MSN materials possessed smaller particle size (about 40-70 nm in diameter), tunable pore sizes (3.8-6.1 nm), high surface areas (700-1100 m(2)/g), and large pore volumes (0.44-1.54 cm(3)/g). We also demonstrate their high potential in conventional DNA loading. Maximum loading capacity of salmon sperm DNA (375 mg/g) was obtained by the use of the M-MSN sample with the largest pore size of 6.1 nm.     

用盐酸分解磷矿石的试验

本文通过用盐酸分解磷矿石制取磷酸所进行的一系列条件试验，找出了较为适宜的磷解磷矿石的条件。试验结果较好，五氧化二磷的分解率为99．14％，二氧化硅的分解率为9．789％。