Thin film nanocomposite forward osmosis membrane prepared by graphene oxide embedded PSf substrate

One of the limiting factors in good performance of forward osmosis (FO) membranes is the internal concentration polarization (ICP). To reduce ICP, thin film nanocomposite forward osmosis (TFN-FO) membranes were fabricated by adding different amounts of graphene oxide (GO) nanoplates (0-1 wt. %) to polymer matrix of polysulfone (PSf) substrate. The prepared nanocomposite membranes exhibited both hydrophilicity and porosity higher than that of neat PSf counterpart. An optimum amount of 0.5 wt% was obtained for GO addition into the membranes. The corresponding fabricated thin film nanocomposite (TFN) membrane (TFNG0.5) revealed a water permeability of 2.44 L/m2hbar which is 66% higher compared to an in-house made composite membrane. The FO performance of TFN was assessed by DI water as feed solution and 1 M NaCl as draw solution in AL-DS orientation. The water flux of the synthesized FO membranes increased upon adding of GO nanoplates and reached to a maximum water flux of 37.74 (L/m2h) for TFNG0.5 membrane. This flux is about 3 times higher than TFC membranes without significant changes in their salt rejection. The higher water flux of the TFN membranes can be attributed to ICP decrease originating from reduction of structural parameter of the membranes

Rheological properties of modified Bitumen: Comparison of waste polymers’ performance

In this investigation, rheological properties of three different polymer-modified bitumen compounds containing recycled polyethylene terephthalate (R-PET), crumb rubber (CR) and poly (styrene-butadiene-styrene) (SBS) are evaluated and compared. The modified samples were tested by a dynamic shear rheometer (DSR) where complex modulus (G*), phase angle (δ) and rutting resistance (G*/Sinδ) of specimens were measured at different temperatures. The obtained results show that the optimum rheological properties will be gained when 7% wt. of a modifier mixture containing R-PET/CR (90/10 weight ratio) is added to the bitumen. In comparison with un-modified bitumen, the one modified by the latter modifier shows phase angle shift 68.9 oC, complex modulus 2190 (Pa) and rutting resistance 2520 (Pa), at temperature 80 oC. Generally, addition of the polymeric modifier increases complex modulus, rutting resistance and rigidity of the bitumen while a little decrease in phase angle is also observed

Effective Parameters on the Phase Morphology and Mechanical Properties of PP/PET/SEBS Ternary Polymer Blends

In this work, ternary polymer blends based on polypropylene (PP)/ polyethylene terephthalate (PET) /poly(styrene-b (ethylene-co-butylene)-b-styrene) (SEBS) triblock copolymer and a reactive maleic anhydride grafted SEBS (SEBS-g-MAH) at various compositions were prepared by co-rotating twin screw extruder. The effects of PET, SEBS and SEBS-g-MAH compatibilizer on morphology of the blends were examined by scanning electron microscopy (SEM). The blends morphology was also estimated by some predicting methods, however, SEM results revealed some contrasts between results of predicting methods and the real morphology. Population of individual and core-shell particles as well as average diameter of the rubber-based cavities is extremely dependent on SEBS, SEBS-g-MA and PET content. Mechanical inspection tests showed that in comparison with the pure PP, addition of SEBS/SEBS-MA causes an increase in the impact strength of the system. Keeping other parameters constant, with increase in SEBS rubbery phase, the core-shell morphology was affected and the impact strength increased consequently. On the other hand, increase in PET content results in modulus increase and the impact strength decrease. Finally, the optimum processing conditions for compounding ternary PP/PET/SEBS blends were achieved

A Review of Manufacturing Process of Polyethylene Pipe and Connectors for Applying in High-Pressure Natural Gas Pipelines

In this article various pipes used for transporting of gas are introduced and pros and cons of each one are elucidated. The pipes are categorized in three different subgroups including metallic, polymeric and metallic-wire reinforced polymeric pipes. Metallic-wire reinforced polymeric pipes are nominated as the best option for usage in high pressure pipelines transporting natural gas. As a result, some information about major manufacturers of this kind of polymeric pipes, raw material, production process and metallic-wire orientation are presented. Finally, from economical point of view, some calculations are done to estimate required amount of polymer and metallic-wire to manufacture such pipes. It is also possible to compare their manufacturing cost with usual metallic and polymeric pipes

INTESTINAL HELMINTHS FROM THE VIEWPOINT OF TRADITIONAL PERSIAN MEDICINE VERSUS MODERN MEDICINE

Background: Traditional Persian Medicine (TPM) has a history of almost 10,000 years with practice and experience aspects. The existing information and experiences of physicians such as Avicenna clearly show the vast amount of knowledge in the classification and treatment of pathogenic worms. The aim of this paper was the description of the various types of helminths along with their treatment in medieval Persia and comparing them with new medical findings. Materials and Methods: We searched main Traditional Persian Medical and pharmacological texts about etiology, manifestation, diagnosis and treatment of worms in the human digestive system and the out come was compared with the data extracted from modern medical sources. A list of medicinal plants was also extracted from traditional pharmacological books and the anthelmintic properties of these plants were checked in Google Scholar, Scopus, PubMed and Ulrich's databases. Results: The results show the existence of theories on pathogenicity, physiopathology, symptoms and the classification of worms in TPM. TPM philosophers have divided worms into four groups and there is not great difference between old Persian and Modern classification. The old Persian scholars have explained a treatment procedure using a list of 48 medicinal plants and the anthelmintic effect of 23 plants have been shown in modern medicine studies. Conclusion: This study shows a more in-depth and thorough classification of pathogenic worms, their pathogenicity, symptoms and treatments in Traditional Persian Medical compared to Greek Medicine so that old Persian classification may be the base of modern taxonomy. More clinical trials are suggested for the efficacy and safety of these plants

Development of Dual-Location Acid and Glutathione Cleavable Block Copolymers for Drug Delivery

The efficiency of chemotherapeutic drugs has been drastically compromised by their undesired side effects. Drug delivery via amphiphilic block copolymer (ABP)-based nanoassemblies has received considerable attention as a new therapeutic method to selectively deliver chemotherapeutic drugs to tumors. Nevertheless, one of the persisting challenges for this therapeutic method is the slow degradation of the nanoassemblies and the sluggish release of encapsulated drugs in the cancer cells. To circumvent this problem, a variety of cleavable linkages have been integrated in the nanoassemblies that can be degraded in response to endogenous stimuli found in tumor environments. Particularly, tumors are known to be acidic and have higher concentrations of cytosolic glutathione (GSH) compared to normal cells. This thesis describes the investigation of novel strategies for the synthesis of dual location acid- and dual acid/GSH-degradable ABPs for intracellular drug delivery. Various ABPs were synthesized via atom transfer radical polymerization (ATRP), reversible addition fragmentation chain transfer (RAFT) polymerization and concurrent ATRP/RAFT polymerization to study their structure-property relationships for effective intracellular drug delivery. These copolymers were designed to have acid-labile acetal or ketal groups and GSH-cleavable disulfide linkages at a junction of hydrophilic and hydrophobic blocks and in hydrophobic blocks. They self-assembled to spherical micelles with cleavable linkages at the hydrophobic core or the interface. The studies of acid or/and GSH-responsive degradation and disassembly revealed that the cleavage of acid- and GSH-cleavable linkages results in disassembly of nanoassemblies through the synergistic shedding of hydrophilic corona as well as the loss of the hydrophobic/hydrophilic balance of micelles core. The nanoassemblies were successfully loaded with Doxorubicin (a clinically used anti-cancer drug) and exhibited enhanced drug release in the presence of acidic or/and GSH stimuli. Promisingly, dual-location acid and acid/GSH degradable nanoassemblies showed biocompatibility, anti-cancer activity and cellular uptake in HeLa cancer cells

Dual Location, Dual Acidic pH/Reduction-Responsive Degradable Block Copolymer: Synthesis and Investigation of Ketal Linkage Instability under ATRP Conditions

Stimuli-responsive degradation (SRD) undergoing chemical transition through the cleavage of labile linkages has been proved to dramatically increase the versatility of stimuli-responsive block copolymers. In particular, dual or multiple stimuli-responsive degradable block copolymers that can be triggered by two endogenous stimuli of acidic pH and reduction are in high demand. Here, a new strategy utilizing atom transfer radical polymerization (ATRP) is reported to synthesize a dual acidic pH/reduction-responsive degradable block copolymer (DLDSRD) labeled with an acidic pH-labile ketal linkage at the block junction and pendant reductively cleavable disulfide groups in hydrophobic block at dual locations. A robust route with multiple steps utilizing carbamate chemistry to endow stability during protection/deprotection steps enables the synthesis of a novel poly­(ethylene glycol)-based ATRP macroinitiator labeled with a ketal linkage (PEG-ketal-Br macroinitiator). Conducting ATRP allows for the synthesis of a series of DLDSRD diblock copolymers consisting of a hydrophilic poly­(ethylene glycol) block covalently conjugated through a ketal linkage with a hydrophobic polymethacrylate block having multiple disulfide pendants. Analysis shows an unexpectedly high degree of polymerization of the hydrophobic polymethacrylate block that could be attributed to the instability of ketal linkages under ATRP conditions. The preliminary results from aqueous micellization and dual acidic pH/reduction-responsive cleavage of ketal and disulfide linkages suggest the feasibility of DLDSRD-based nanoassemblies toward effective drug delivery exhibiting precisely controlled release in response to dual stimuli at dual locations (core and interfaces)

Comparison of mechano- and PhotoATRP with ZnO nanocrystals

Zinc oxide (ZnO) was previously reported as an excellent cocatalyst for mechanically controlled atom transfer radical polymerization (mechanoATRP), but its photocatalytic properties in photoinduced ATRP (photoATRP) have been much less explored. Herein, well-defined ZnO nanocrystals were prepared via microwave-assisted synthesis and applied as a heterogeneous cocatalyst in mechano- and photoATRP. Both techniques yielded polymers with outstanding control over the molecular weight, but ZnO-cocatalyzed photoATRP was much faster than analogous mechanoATRP (conversion of 91% in 1 h vs 54% in 5 h). The kinetics of photoATRP was tuned by loadings of ZnO nanocrystals. PhotoATRP with ZnO did not require any excess of ligand versus Cu, in contrast to mechanoATRP, requiring an excess of ligand, acting as a reducing agent. ZnO-cocatalyzed photoATRP proceeded controllably without prior deoxygenation, since ZnO was involved in a cascade of reactions, leading to the rapid elimination of oxygen. The versatility and robustness of the technique were demonstrated for various (meth)acrylate monomers with good temporal control and preservation of end-group functionality, illustrated by the formation of tailored block copolymers.NSF [DMR 2202747, CHE 2108901]; J. W. Fulbright Commission in the Czech Republic [2022-21-1]; Ministry of Education, Youth and Sports of the Czech Republic; Fonds de recherche du Queebec (FRQNT) [RP/CPS/2022/007]; [301734]National Science Foundation, NSF, (CHE 2108901, DMR 2202747); US-UK Fulbright Commission, (2022-21-1, RP/CPS/2022/007); Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Fonds de recherche du Québec – Nature et technologies, FRQNT, (301734); Fonds de recherche du Québec, FR