Sharif Digital Repository

Keggin-type polyoxometalate (POM) nanoparticles based on [PW12O40]3- and [SiW12O40]4- with Ag+ and (ZrO)2+ cations were prepared under ultrasound irradiation. The results of SEM and XRD revealed the average size of particles in the range of 24–95 nm. The moles of crystallization water per mole of nanocatalysts were in the range of 3–9. EDX spectra confirmed the successful replacement of protons of H3PW12O40 and H4SiW12O40 with Ag+ and (ZrO)2+ cations. These nanoparticles were used as heterogeneous catalysts for the synthesis of a poly (amido-ester) at room temperature. All polymers were fully characterized. Although employing the nanocatalyst resulted in at least 22% improvement in the... 

Preparation and evaluation of chitosan-coated eggshell (CTS-ES) particles as a biosorbent for removal of Cu(II) ions from aqueous media was considered in this research. For this purpose, chitosan was coated on eggshell (ES) particles through precipitation procedure. The coated particles were characterized by Fourier transform infrared, thermogravimetric analysis, and field emission scanning electron microscopy analysis. Kinetic studies showed that coating of chitosan on ES particles improved their Cu(II) adsorption capacity. The removal of Cu(II) ions by either ES or CTS-ES particles followed the pseudo-second-order kinetics, indicating that chemical sorption is the rate-limiting step for... 

Preparation and evaluation of chitosan-coated eggshell (CTS-ES) particles as a biosorbent for removal of Cu(II) ions from aqueous media was considered in this research. For this purpose, chitosan was coated on eggshell (ES) particles through precipitation procedure. The coated particles were characterized by Fourier transform infrared, thermogravimetric analysis, and field emission scanning electron microscopy analysis. Kinetic studies showed that coating of chitosan on ES particles improved their Cu(II) adsorption capacity. The removal of Cu(II) ions by either ES or CTS-ES particles followed the pseudo-second-order kinetics, indicating that chemical sorption is the rate-limiting step for... 

The authors consider the problem of finding a minimum cost multicast sub-graph based on network coding, where delay values associated with each link, limited buffer-size of the intermediate nodes and link capacity variations over time are taken into account. The authors consider static multicast (where membership of the multicast group remains constant for the duration of the connection) in lossless wireline networks. For such networks, first the continuous-time (asynchronous packet transmissions) model is formulated. Subsequently, the discrete-time model for the synchronous packet transmissions scenario is derived. Then, by using an auxiliary time-expanded network, a decentralised algorithm... 

Thin film composites (TFCs) as forward osmosis (FO) membranes for seawater desalination application were prepared. For this purpose, polyacrylonitrile (PAN) as a moderately hydrophilic polymer was used to fabricate support membranes via nonsolvent-induced phase inversion. A selective thin polyamide (PA) film was then formed on the top of PAN membranes via interfacial polymerization reaction of m-phenylenediamine and trimesoyl chloride (TMC). The effects of PAN solution concentration, solvent mixture, and coagulation bath temperature on the morphology, water permeability, and FO performance of the membranes and composites were studied. Support membranes based on low PAN concentrations (7 wt...