Effect of Nanopatterning on Concentration Polarization during Nanofiltration

Membranes used for desalination still face challenges during operation. One of these challenges is the buildup of salt ions at the membrane surface. This is known as concentration polarization, and it has a negative effect on membrane water permeance and salt rejection. In an attempt to decrease concentration polarization, a line-and-groove nanopattern was applied to a nanofiltration (NF) membrane. Aqueous sodium sulfate (Na2SO4) solutions were used to test the rejection and permeance of both pristine and patterned membranes. It was found that the nanopatterns did not reduce but increased the concentration polarization at the membrane surface. Based on these studies, different pattern shapes and sizes should be investigated to gain a fundamental understanding of the influence of pattern size and shape on concentration polarization.

Silver-Chitosan Nanocomposite Prepared With Aqueous Sodium-hydroxide and Aqueous Acetic Acid Solutions: Characteristics and Their Cytotoxic Effects

In this study cytotoxic effects of silver-chitosan nanocomposites with aqueous sodium-hydroxide solution (SCNC-ASHS), and aqueous acetic acid solution (SCNC-AAAS) were evaluated, in vitro. The morphology of the synthesized nanoparticles were characterized by Fourier-Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). Their cytotoxicity were then evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) in concentrations of 1.56 to 400 µg/ml, and acridine orange/ethidium bromide (AO/EB) staining after 24h and 48h. Results showed the cytotoxicity of 400 µg/ml of SCNC-ASHS on Vero and HT-29 cells of 80.57% and 84.37% after 24h, and 82.20% and 84.84% after 48h. While, the values for SCNC-AAAS on Vero and HT-29 cell-lines were respectively 80.63% and 87.64% after 24h, and 83.60% and 87.44% after 48h. The most toxicity on HT-29 cells was belonged to SCNC-AAAS with IC50 of 40.4 µg/ml. In the staining procedure, cell viability for 25 µg/ml concentration of SCNC-AAAS was 41.84% in HT-29 cell and, for 6.25 µg/ml of SCNC-AAAS was 37.51% in Vero cells. A considerable decrease in cell viability was observed. Types of nanoparticles, synthesis methods, and different cell lines play role in inducing cytotoxicity. Anti-cancer effect of the nanoparticles on the colon cancerous cells (HT-29), of that SCNC-AAAS displayed higher effect than SCNC-ASHS.

Hippurate hydrolisis test for group B Streptococcus identification. v1

The hippurate test is used to identify group B Streptococcus which, unlike groups A, C, F and G, can hydrolyze 1% aqueous sodium hippurate to produce glycine and sodium benzoate, by adding ninhydrin, glycine it is deaminated by the oxidizing agent which reduces and turns purple.