Immobilization of biologically active species on PA‐6 foils treated by a dielectric barrier discharge

In the field of biomaterials and biomedical devices, surface activation has been focused on creating functional groups capable of preferential adsorption of biologically active species (proteins, enzymes, cells, drugs, etc.). In this way an interface can be created between the synthetic material and the biological medium, with the aim of increasing the compatibility of the implant with the human organism. In our experiments a dielectric barrier discharge (DBD), in helium at atmospheric pressure, was used as the source of energy capable of creating active centers that render the functionalized surface favorable to immobilization of biological molecules. Retention of immunoglobulin (IgG) and heparin biomolecules on polyamide‐6 (PA‐6) surfaces after treatment by the DBD was analyzed by atomic force microscopy, adhesion evaluation, and measurement of the contact angle titration in order to assess this incorporation on the treated surfaces. The marked adsorption of the biomolecules on the active sites created by DBD on the exposed surfaces also was related to a complex set of processes, such as enhanced roughness, increased surface wettability, and modified distribution of cationic and anionic groups on the treated surfaces. All these factors could promote interfacial interactions between the specific groups of the biomolecules existing in the biological medium and the type of cationic and/or anionic groups present on the surface. The efficiency of the DBD treatment showed that the DBD technique is useful for preactivation of the polymer surface for immobilization of other biologically active species (such as drugs and enzymes). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1985–1990, 2003     

Synthesis of carbon nanocapsules containing Fe, Ni or Co by arc discharge in aqueous solution

A simple, inexpensive and one-step synthesis method of metal-containing carbon nanocapsules using an arc discharge in aqueous solution is reported. It was found that Ni, Co and Fe nanoparticles could be in situ encapsulated in carbon shells when the arc was performed respectively in aqueous solutions of NiSO₄, CoSO₄ and FeSO₄. Transmission electron microscopy, energy dispersive X-ray spectroscopy and electron diffraction patterns of selected areas were used to determine the crystalline phase of the metal cores. To explain the formation mechanism of metal-containing carbon nanocapsules, a model of discharge in solution is proposed. This result presents a simply controllable way to synthesize metal-containing carbon nanocapsules.     

Charge transfer effects in acid treated single-wall carbon nanotubes

Single-wall carbon nanotubes (SWNTs) prepared by the arc discharge method were oxidized using nitric acid. The samples were analyzed by using Raman scattering and Fourier transformed infrared spectroscopy (FTIR). The FTIR results indicate the presence of -COOH acid groups in the treated samples. The up shifts observed in the radial breathing mode frequencies suggest that SWNTs behave as donors after the acid treatment, with charge transfer occurring from the nanotubes to the -COOH groups. Ab initio calculations of SWNTs interacting with -COOH acid groups support the charge transfer process from the nanotubes to the carboxyl groups.     

圆弧齿轮的解析法设计计算

本文对目前在仪器仪表中采用的圆弧齿轮进行了分析,在图解法设计的基础上,推出了一套解析法设计计算方案。     

企业大数据治理研究

介绍了面对大数据的数据量大、种类多、速度快和高价值的处理技术挑战,企业应当如何建立可靠的大数据平台。利用信息架构原则和实践,实现大数据与企业数据的灵活集成,通过结合使用分布式文件系统、NoSQL与关系型数据库,企业可以获取、组织和分析其所有企业数据(包括结构化和非结构化数据),从而做出最科学的决策。     

脉冲放电高能转化制备纳米粉体

综合介绍了脉冲电流通过细金属丝放电(pulsed wire discharge,PWD)制备纳米粉体的方法.讨论了影响纳米粉体,特别是晶粒尺寸的因素,以防止形成亚微米颗粒.因为达到电压峰值的丝的沉积能相当于丝的汽化能,因此,能夠计算出沉积能.随着所施加的能量增加,气体压力降低,介质气体的热扩散率增大,晶粒尺寸变小.在惰性气氛中,采用PWD工艺,由金属蒸气急冷可制备金属粉体.如果介质气体变为氧气或者氨气,就能制备氧化物、氮化物纳米粒子.要制备双金属合金、双氧化物或氮化物纳米粒子就必需采用双金属丝和不同的介质气体.采用PWD工艺,在有机气体或烟气中,能制备电磁屏蔽和导电浆料和其它用途的钝化纳米粒子.采用丝输送器而实现大量生产纳米粉体的PWD工艺一个实例证明了PWD工艺生产纳米粉体的可行性.     

Synthesis, isolation, spectroscopic and electrochemical characterization of some calcium-containing metallofullerenes

A few Ca-containing mono-metallofullerenes, i.e. Ca@C₇₆, Ca@C₈₈, Ca@C₉₀ (I, II), were synthesized by an improved DC arc discharge method and isolated by a multi-stage HPLC method for the first time. These isomer-separated metallofullerenes were characterized by LD-TOF MS and UV-vis-NIR spectrometry. Their HOMO-LUMO band gaps and possible molecular geometries are discussed according to the absorption spectra in this report. In addition, the cyclic and differential pulse voltammetry of Ca@C₇₆ was conducted in MeCN/C₆H₅CH₃ (1:4 v/v). The voltammograms of Ca@C₈₂ (II, III) and Ca@C₈₄ (II) were also recorded. Their electrochemical behaviors are discussed compared with those of corresponding ytterbium metallofullerenes. The features of the Ca metallofullerenes’ electronic structures are also discussed.     

Thermolysis of the polyyne C8H2 in hexane and methanol: Experimental and theoretical study

The mean lifetimes of polyyne C₈H₂ in hexane were determined at 50, 60, 80, and 100 °C and in methanol at 60 °C. The reactions are second order at all temperatures: ln k₂ = 20.5 ± 1.5-10303 ± 520T⁻¹ and the corresponding activation energy is 85.7 ± 6.3 kJ mol⁻¹ (7164 cm⁻¹). Extrapolation suggests that solutions at 1 mM concentration are significantly unstable at room temperature. Quantum chemical calculations show that polyynes C_mH₂ + C_nH₂ (m + n = 16) could be products, but these were not detected. Alternatively, C₁₆H₂ isomers could form. IR spectra of the solid residues from hexane and methanol solutions were obtained.     

Application of pulse discharge sintering (PDS) technique to rapid synthesis of Ti3SiC2 from Ti/Si/C powders

To synthesize Ti₃SiC₂ samples, pulse discharge sintering (PDS) technique was utilized to sinter elemental powders of Ti/Si/C with stoichiometric and off-stoichiometric ratios in a temperature range of 1200–1500 °C. The results showed that high purity Ti₃SiC₂ could not be obtained from the Ti/Si/C powder with molar ratio of 3:1:2, and Ti₃SiC₂ preferred to form at relatively low sintering temperature for a short time. When 5Ti/2Si/3C and 3Ti/1.5Si/2C powders were sintered for 15 min, the TiC content was respectively decreased to 6.4 and 10 wt.% at 1250–1300 °C. The corresponding relative density of the samples sintered from 5Ti/2Si/3C powder was calculated to be as high as 99% at the temperature above 1300 °C. It is suggested that low-temperature rapid synthesis of Ti₃SiC₂ would be possible through the PDS technique, provided that the composition of the starting powders should be adjusted to be off-stoichiometric ratio from 3:1:2.