Cryogenic induced phase separation of chitosan solution——A novel method for preparation of membrane with high porosity

The chitosan porous membrane was prepared by extending the principle of thermally induced phase separation (TIPS) for the polymer-diluent system to the polymer solution at ambient temperature to carry out the cryogenic induced phase separation (CIPS). The porous membrane obtained was characterized by scanning electron microscopy (SEM) and gas permeability. It was found that a specific lacy pore structure morphology corresponding to the TIPS' solid-liquid phase separation was formed in the demixing process and the porosity could be more than 70%. The research of demixing mechanism and membrane-formation process showed that the membrane was stacked through porous lamella. The porosity of membrane increases and the pore diameter decreases with increasing solidifying temperature. Both the porosity and pore diameter decrease with the chitosan concentration increase.     

Effect of Aβ1-40 on membrane permeability and intracellular free Ca2+ of nerve cells

The effects of soluble and fibrillar Aβ1-40 on membrane permeability and intracellular free Ca^2 of nerve cells were investigated by the laser confocal microscopy. Results indicate that: i) Effects of soluble and fibrillar Aβ1-40 on cell membrane permeability are both concentration-dependent. Soluble Aβ1-40 increases membrane permeability only at concentration of 3μmol/L, while the toxic effect of fibrillar Aβ1-40 is much stronger, its evident effect begins from 1μmol/L. When its concentration rose to 3μmol/L, not only the membrane permeability increased, but also the nuclear membrane broke seriously, ii) Both soluble and fibrillar Aβ1-40 at high concentrations increased the intracellular free Ca^2 , and the increased amplitudes are concentration-dependent. However, the fibrillar one induces the increase of intracellular Ca^2 much quicker and synchronously.These results indicate that some correlation exists between the neurotoxicity of high concentration soluble and fibrillar Aβ1-40 and the change of physico-chemical properties and intracellular Ca ion imbalance.     

A novel TiO2 with a large amount of bulk intrinsic defects-Visible-light-responded photocatalytic activity induced by foreign trap

A novel TiO2 (anatase) containing a large amount of single electron trapped oxygen vacancies (SETOV) was prepared by dehydration of titanic acid nanotubes. This novel TiO2 contains high concentration intrinsic defects in bulk structure, while its surface still remains the stoichiometric structure to protect them. And this novel TiO2 itself has the visible light absorption without any doping, so we call it as the third generation of TiO2 . However, it is regretted that this novel TiO2 (A) only has photocatalytic activity under UV light irradiation, and was inactive for the visible light. The true reasons for this phenomenon were investigated by the transient IR absorption and photoluminescence spectra. Through constructing the foreign electron traps (PdO, PtO2 ), the photocatalytic oxidation of propylene under visible light irradiation was successfully achieved. The removal yield of propylene (C3H6 ) reached 7.6% and 28% on 2 wt.% PtO2 /novel TiO2 and 2 wt.% PdO/novel TiO2 , respectively. By comparison with the noble metal electron traps (Pt, Pd), we found that the effective foreign electron traps need to satisfy two conditions: (1) its work function should situate in the range of Eg(TiO2 ); (2) O2 adsorbes on it undissociatively. This work opens up a new route for the investiga- tion of solar-energy-available TiO2 .     

Separation and analysis of the soluble trimer of Aβ1-40 and its effects on the rise in intracellular calcium

Alzheimer’s disease (AD) is one of the progressive neurodegenerative diseases associated with protein conformational transition, generally known as protein conformational disorders[1]. The general characteriza- tions of AD are the intracellular fibrillar…