Sharif Digital Repository

As membrane distillation (MD) is an under-developed separation process, specific membranes for MD applications are not yet commercially available. Therefore, microporous polymeric membranes made of hydrophobic materials fabricated for microfiltration purposes are usually used for MD applications. Characterization of such kind of membranes is important in order to achieve a better in-depth understanding of their performance and to fabricate specific membranes for MD process. One of the emerging characterization methods is atomic force microscopy (AFM) analysis. AFM is a newly developed high-resolution method that is useful for studying the surface topography of various types of membranes, and... 

Electrospun hybrid membranes were synthesized using electrospinning of Poly (vinylidenefluoride) - titanium tetraisopropoxide (PVDF-TTIP) sol. Asymmetric post-treatment of membrane conducted for deprotonation of titanate and making hydrophilic/hydrophobic dual characteristics. The membranes were characterized by various methods such as wettability, scanning electron microscopy, infrared spectroscopy, X-ray diffraction and liquid entry pressure tests. For evaluating the separation performance, these membranes were applied in the VMD process to treat water heavy metal contaminants. The effects of operating parameters such as flow rate, temperature and membrane properties as porosity, on... 

Thin porous membranes are important components in a microfluidic device, serving as separators, filters, and scaffolds for cell culture. However, the fabrication and the integration of these membranes possess many challenges, which restrict their widespread applications. This paper reports a facile technique to fabricate robust membrane-embedded microfluidic devices. We integrated an electrospun membrane into a polydimethylsiloxane (PDMS) device using the simple plasma-activated bonding technique. To increase the flexibility of the membrane and to address the leakage problem, the electrospun membrane was fabricated with the highest weight ratio of PDMS to polymethylmethacrylate (i.e., 6:1... 

Gating of mechanosensitive (MS) channels is driven by a hierarchical cascade of movements and deformations of transmembrane helices in response to bilayer tension. Determining the intrinsic mechanical properties of the individual transmembrane helices is therefore central to understanding the intricacies of the gating mechanism of MS channels. We used a constant-force steered molecular dynamics (SMD) approach to perform unidirectional pulling tests on all the helices of MscL in M. tuberculosis and E. coli homologs. Using this method, we could overcome the issues encountered with the commonly used constant-velocity SMD simulations, such as low mechanical stability of the helix during...