Negatively-charged nanofiltration membrane and its hexavalent chromium removal performance.

To enhance hexavalent chromium (Cr(VI)) removal performance under acidic conditions, the nanofiltration (NF) membrane with enhanced negative charge was fabricated via introducing 2, 5-diaminobenzenesulfonic acid (DABSA) into polyamide layer. The control membrane (NF-P) was directly prepared from piperazine and 1, 3, 5-benzenetricarbonyltrichloride. Surface chemical compositions, morphology, surface charge, pore size, permeability and pH-dependent separation performance of the fabricated membranes were characterized. The membranes showed the similar water permeance (∼11.5 L m-2 h-1 bar-1) and Na2SO4 rejections (∼98%) under neutral environments. The DABSA introduced NF membrane (NF-PD) was negatively charged in the pH range of 2.5-11, while the isoelectric point for NF-P was ∼pH 4.0. Cr(VI) removal ability was then evaluated under various concentrations and pH environments. The results indicated that NF-PD showed the better Cr(VI) rejection performance in all tested conditions than NF-P, especially under acidic environments (e.g., pH 4 and pH 5). Moreover, there was a fluctuation of the rejection with the increase of Cr(VI) concentration under acidic environments, which was mainly caused by the formation of Cr2O72- species. The harmful Cr(VI) was efficiently removed by the NF membrane with enhanced negative charge under acidic environments, which indicated the wider application range of the NF membrane.

[Clinical significance of serum vascular endothelial growth factor in patients with multiple myeloma].

This study was purposed to investigate the relation of serum vascular endothelial growth factor (VEGF) levels with clinical types and therapeutic efficacy of multiple myeloma (MM), and to analyze the significance of VEGF in MM. The levels of serum VEGF were detected by enzyme-linked immunosorbent assay (ELISA) technique in 76 patients with MM. The relationship between the serum VEGF levels with MM patients' age, stages, types, and efficacy were analyzed. The results showed that the patients who were less than 65 years old had higher serum VEGF levels than elder patients, however, the difference between them had no statistical significance (P > 0.05). The VEGF level was the highest in IgG type patients, and then in light chain type, lowest in IgA type, however there were no statistical differences between them (P > 0.05). Patients of DS stage III had higher VEGF level than that of stage II, and there was also no statistical difference (P > 0.25). Patients of ISS stage I had lower VEGF level than that of stage II and III, and it also showed no statistical difference (P > 0.05). After treatment, patients obtained complete remission (CR) or very good partial remission (VGPR) had decrease of serum VEGF level, however, patients obtained less than partial remission (PR) had increase of serum VEGF level. Patients were divided into two groups according serum VEGF level ( ≤ 150 ng/L), patients with high VEGF levels had short overall survival time, there was statistical difference (P = 0.03). It is concluded that the serum VEGF level of MM patients dose not relate with age, clinical stages and M protein types; however, there was a certain association between overall survival and serum VEGF level, and the later may be one of poor prognostic factors.

[Studies on the dispersion and deposition behavior of nano-TiO2 in aquatic system].

The existing form and environmental behavior of nTiO2 in aquatic system are mainly affected by environmental factors. The dispension and deposition behavior of nTiO2 was investigated by changing pH values of the suspension liquid and adding electrolytes and surfactants using P25 nano-TiO2 as the research object. The results indicated that the pH value obviously affected the stability of nTiO2 by changing the charge distribution on the nTiO2 particles. TiO2 nanoparticles were highly aggregated to deposit when the pH value was close to the isoelectric point. The characteristic adsorption ion of AlCl3, CaCl2, NaCl and Na2SO, after ionization on the surface of nTiO, particles varied from each other. The adsorption of cations neutralized the negative charge on the surface of nTiO2 particles which led to the quick aggregation and deposition of nTiO2 particles. The adsorption of anions improved the stability of nTiO2 particles in water by increasing electrostatic repulsion between TiO2 particles. Surfactants would adsorb onto the surface of nTiO2 particles and enhance the stability of nTiO, by changing the surface properties of the nanoparticles. The potential energy of nTiO2 particles were simulated by the DLVO theory. The simulative potential energy curve confirmed that the change of relevant water environment conditions led to the change of potential energy of nTiO, particles, which determined the dispension and deposition behavior of nTiO2 particles.