Oxidization Degree Research Articles

Electrospun regenerated cellulose nanofiber affinity membrane functionalized with protein A/G for IgG purification

The aim of this work is to prepare protein A/G functionalized electrospun regenerated cellulose (RC) nanofiber mesh as affinity membrane for immunoglobulin G (IgG) purification. Cellulose acetate (CA) nonwoven nanofiber membrane was prepared by electrospinning, followed by heat treatment and alkaline treatment to obtain RC nonwoven nanofiber membrane. After oxidization of the RC membrane by NaIO 4, protein A/G was covalently immobilized on the membrane, giving an affinity membrane capable of specifically capturing IgG molecules. Physical and chemical properties of the affinity membrane were characterized. Surface chemistry of the membranes during the membrane modification process was monitored with XPS and ATR-FTIR. Oxidization degree of the RC membrane was optimized to get a high ligand binding capacity without too much loss of mechanical strength for handling of the material. Ligand (protein A/G) amount immobilized on the RC membrane oxidized for 9 h was measured as 30 μg/mg and the membrane's IgG binding capacity was measured as 18 μg/mg. The IgG purification ability of the affinity membrane was evaluated with BSA as a model impurity. Five layers of the cellulose affinity membrane were packed into a spin column to separate IgG from an IgG/BSA mixture solution. SDS-PAGE analysis showed that the BSA was completely removed after the purification.

Effects of titanium coating on property of diamond

The titanium film was coated on the surface of diamond crystal in order to improve the chemical properties of diamond and the effect of titanium coating on the property of diamond was discussed. The anti-impacting strength, the oxidization process and the soakage property between vitrified bond and diamond were investigated. It is found that, when the titanium film is coated on the surface of diamond crystal, the soakage angle between vitrified bond and diamond decreases from 39.5° to 34.5° at 993 K, and the oxidization degree on the surface of diamonds is lowered greatly.

Electrical Resistivity and Magnetoresistance in Monodispersed Oxide-Coated Fe Cluster Assemblies

We systematically studied electrical resistivity and magnetoresistance (MR) of size-monodispersed oxide-coated Fe cluster assemblies with the mean cluster sizes of d = 9–17 nm prepared by a plasma-gas-condensation-type cluster beam deposition system. The electrical resistivity and magnetoresistance strongly depend on the temperature, surface oxidization degree of the clusters (namely O2 gas flow ratio RO2), Fe cluster size d, and magnetic field. The oxide-coated Fe cluster assemblies exhibit a large negative MR effect which is further enhanced at low temperatures due to the dominant contribution of the spin-dependent tunneling process between the Fe cores through the oxide shell layers. It has been found that the magnetic field dependence of the MR ratio at all temperatures shows no saturation tendency up to a maximum field H = 50 kOe and completely disagrees with the magnetization curves which indicate a saturation tendency. These results have been interpreted by consideration of the magnetic state of the Fe-oxide shell layers, spin-dependent tunneling mechanism, and intercluster magnetic correlation. The high-field nonsaturation behavior in the magnetoresistance effect is attributed to the spin-disordered structure, which is frozen in a spin-glass-like state at low temperatures, in the surface of the Fe-oxide shell crystallites or the whole thinner Fe-oxide shell layers.

Preparation and spectral properties of new molecular conductors based on anion salt

Preparation, IR, UV—Vis and X-ray photoelectron spectroscopy (XPS) of three molecular conductors derived from metal complexes of DMID ligand [TBA] 0.6[Ni(DMID) 2], [TBA] 0.44][Ni(DMID) 2] and TTF[TBA] 0.35[Ni(DMID) 2] 2 are reported (DMID = 1,3-dithiolene-2-one-4,5-dithiolate, TBA = tetrabutylammonium, TTF = tetrathiafulvalene). Electronic spectra show that the characteristic π-electronic delocalization absorption band over the ligand through π—d interactions in the complexes red-shifts with the increase of oxidization degree. In addition, XPS shows that there is a characteristic ‘satellite’ peak centered at around 168.7 eV, higher by about 4.7–5.4 eV than the main peak, in the S(2p) core-level region spectra of these partially oxidized or charge transfer conductive bisdithiolene metal complexes and, furthermore, the relative intensity of the ‘satellite’ peak increases with the oxidization degree of the complexes.