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Some defects of polylactic acid (PLA), especially its poor mechanical properties, were modified using a minimum content of non-biodegradable maleated polypropylene (MAPP). To this end, first, the amount of MAPP was optimized, which was 20 wt.%. Second, MgO was used as a new catalyst to improve the exchange reactions between active groups in both polymers in a reactive blending process. Tensile and izod analyses showed that, compared to neat PLA, with a slight decrease in modulus and tensile strength, elongation at break, and impact resistance were improved in the presence of 20 and 0.1 wt.% of MAPP and MgO, respectively. This improvement in mechanical properties can be related to the exchange reactions between two polymers and the formation of PLA-MAPP block copolymers. MFI and WDCA analyses demonstrated the increase in melt flowability and surface hydrophilicity of the resulting blends, respectively. DSC analysis showed that the Tg values of both polymers approached each other in the presence of catalyst. Also, the elimination of cold crystallization of PLA and the decrease in the Tm and crystallinity of both polymers are clear reasons for the miscibility of the alloy. TEM displayed the proper dispersion of MgO nanoparticles within the polymer matrix, and in addition, the XRD test also proved the decrease in the crystallinity of both polymers and appropriate miscibility of the samples containing 20 and 0.1 wt.% of MAPP and MgO, respectively. These results can promise the design of a compound with the maximum amount of PLA for further use in various industries. [ABSTRACT FROM AUTHOR]

Objective: The release behavior of Lacticaseibacillus rhamnosus from single bilayer microcapsules of alginate-chitosan (AC) and its double bilayer (ACAC) was investigated in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). Methods Multilayer polyelectrolyte AC microcapsules were fabricated using the layer-by-layer (LbL) self-assembly technique through electrostatic interactions. Results AC and ACAC microcapsules kept their integrity and mechanical stability in simulated gastric conditions. Bacterial cells remained inside microcapsules in SGF and dissolution of microcapsules was observed in SIF. To improve the bacterial survivability, L. rhamnosus was co-encapsulated in a double bilayer of AC hydrogels with calcium carbonate as an antacid agent. Conclusions The LbL self-assembly technology provides stable and target release for ACAC microcapsules. Therefore, the double bilayer polyelectrolyte microcapsules have a remarkable potential for successful application in the targeted and controlled delivery of different probiotics and drugs. [ABSTRACT FROM AUTHOR]

A TiO2@WO3/ZnO photocatalyst was synthesized and employed in the degradation of methyldiethanolamine (MDEA) (a pollutant of wastewater from gas refinery complexes) under LED light. The synthesized photocatalyst was characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectrometry (FT-IR). In the wastewater treatment process, a number of experiments were designed by central composite design, where parameters including the irradiation time, pH, TiO2@WO3/ZnO catalyst mass and MDEA concentration involved in the process were optimized. The significance of the individual parameters and their possible interactions were investigated using analysis of variance. The optimum values of 30 min, 9, 0.15 g, and 0.4% were obtained for the irradiation time, pH, TiO2@WO3/ZnO catalyst mass ratio and the initial concentration of MDEA, respectively. Under such conditions, the photodegradation percentage of MDEA was 86%, and a maximum photocatalytic activity with 72% degradation of gas refinery effluent was achieved in 70 min. [ABSTRACT FROM AUTHOR]

Geopolymers are inorganic alumina-silicate materials produced from raw materials, rich in silica (SiO2) and alumina (Al2O3), in combination with an alkaline activator solution. In this study, geopolymer of class C flay ash in ambient curing condition were used form geopolymer mortar and effects of different alkaline activator solutions and variations of associated parameters, were investigated. The obtained results indicated that in ambient curing condition (23±2°C), using sodium hydroxide and sodium silicate as an alkaline activator solution, result in higher 7- and 28-day compressive strength of geopolymer mortar compared to potassium-based (potassium hydroxide and potassium silicate) and combination of sodium and potassium-based alkaline activator solutions, approximately 49% and 145%, respectively. But, in term of 90°C curing condition, potassium-based alkaline activator subject to higher 7- and 28-day compressive strengths. Additionally, simultaneous inclusion of NaOH and KOH led to decline the compressive strength. Also, obtained results of experimental data show that optimal ratio 1.5–2 of SiO2/Na2O were highest compressive strength. [ABSTRACT FROM AUTHOR]

Natural gas has wide range of acid gas concentrations such as CO2 and H2S. Alkanolamines dissolved in aqueous solutions are commonly employed to scrub CO2 and H2S from natural gas. As a result, the high level of this polutant is emitted through the waste water during cleaningIn this study a novel photocatalyst, TiO2@WO3/ZnO, has been designed and fabricated. To prepare the catalyst with the highest performance, the optimized weight fraction of WO3+Zno (with 1:4 weight ratio) has been alloyed with TiO2. The results from BET and BJH indicated that the synthesized catalyst had relatively high specific surface area (10.3 m² g-1) and mesopore structure with cavities diameter of 10.9 nm. The as-synthesized photocatalyst has been employed in the alkanolamine contaminant degradation of wastewater obtained from an industrial gas refinery plant in the presence of LED light. In this regard, the degradation of alkanolamine during time was monitored using UV-Vis and fluorescence spectroscopies. The obtained results confirmed high performance of the designed catalyst in the rapid treatment of the wastewater of gas refinery effluent at very low catalyst loading of only 0.5 wt.%, thereby making it a good candidate for the catalytic purposes. Finally, a possible mechanism for catalytic degradation of alkanolamine over TiO2@WO3/ZnO was suggested. [ABSTRACT FROM AUTHOR]

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Currently, air separation units (ASUs) have become very important in various industries, particularly oil and petrochemical industries which provide feed and utility services (oxygen, nitrogen, etc.). In this study, a new industrial ASU was evaluated by collecting operational and process information needed by the simulator by means of HYSYS software (ASPEN-ONE). The results obtained from this simulator were analyzed by ASU data and its error rate was calculated. In this research, the simulation of ASU performance was done in the presence of an expansion turbine in order to provide pressure inside the air distillation tower. Likewise, the cooling capacity of the cooling compartment and the data were analysed. The results indicated that expansion turbine is costly effective. Notably, it not only reduces the energy needed to compress air and supply power of the equipment, but also provides more cooling power and reduces air temperature. Moreover, turbines also increase the concentration of lighter gas products, namely nitrogen. [ABSTRACT FROM AUTHOR]

Polyolefin elastomers (POEs), a new family of synthetic commercialized polymers, can be used as an alternative for lots of common elastomers such as ethylene propylene rubbers (EPR or EPDM), poly (ethylene-co- vinyl acetate) (EVA) and poly (styrene-co-butadiene) (SBR). In this research, 1-hexene/1,5-hexadiene copolymer (COPOLY), as a newfound POE was cured with different weight fractions of dicumyl peroxide (DCP) as a curing agent. Curing behavior and ultimate properties of COPOLY were compared with EPDM as a nearby practical and commercial rubber. Mooney viscosity results showed that; by increasing weight fraction of curing agent, scorch times decreased, and the scorch time of COPOLY was lower than EPDM. Tensile measurements showed that COPOLY has comparable Young's modulus with it in EPDM sample (16.11 and 16.51 MPa, respectively). DMTA analysis confirmed more toughness and elastomeric properties of COPOLY in comparison to EPDM rubber. Melt viscosity analysis of the samples exhibited that synthesized rubber has lower melt viscosity than EPDM at all frequency ranges, and also EPDM showed slightly higher elastic modulus in comparison to COPOLY (0.89 and 0.82 GPa, respectively). Fatigue test acknowledged excellent behavior of COPOLY with 45,600 cycles till to failure. The synthesized COPOLY showed significantly higher ozone resistance (142 toward 105 h) and lower abrasion weight loss (11.34 toward 14.28%) than commercial EPDM. Altogether, our obtained results suggest new highly efficient rubber that in all studied aspects has higher capability than EPDM and can be considered as a high performance rubber in industrial applications. [ABSTRACT FROM AUTHOR]

In this study, a refrigeration cycle was simulated with different refrigerants in a petrochemical plant in Iran. Using Aspen HYSYS Software, necessary modifications were checked as much as possible and optimum values for important parameters affecting cycle of the optimized simulators in the Aspen HYSYS were found. Having found the most economical refrigeration cycle, financial expenses were reduced in the refrigeration cycle. Then, results from the simulation by Aspen HYSYS and Icarus software were compared with actual values of the petrochemical plant under study, and the most efficient and economical strategies to achieve the desired cycle were suggested. Energy consumption of the compressors was optimized by creating a Joule–Thomson balance between VLV-100 and the compressor power of the refrigeration cycle, which reduces the cost of utilities in the refrigeration cycle. The aim of this study is process optimization of the refrigeration cycle economically and also use of the environmental friendly refrigerants. [ABSTRACT FROM AUTHOR]

In this study, a multi-objective design optimization method based on a radial basis function (RBF) model was applied to minimize the volumetric shrinkage and warpage of hip liners as an injection-molded biomedical part. The hip liners included an ultrahigh molecular weight polyethylene (UHMWPE) liner and UHMWPE reinforced with a nano-hydroxyapatite (nHA) liner. The shrinkage and warpage values of the hip liners were generated by simulation of the injection molding process using Autodesk Moldflow. The RBF model was used to build an approximate function relationship between the objectives and the process parameters. The process parameters, including mold temperature, melt temperature, injection time, packing time, packing pressure, coolant temperature, and type of liner, were surveyed to find the interaction effects of them on the shrinkage and warpage of the liners. The results indicated that the addition of nHA helps the liners to obtain more dimensional stability. The model was validated by the k-fold cross validation technique. Finally, the model revealed the optimal process conditions to achieve the minimized shrinkage and warpage simultaneously for various weights. [ABSTRACT FROM AUTHOR]

Nowadays, carbon nano (CN) structures and specifically carbon nanotubes (CNTs), because of the nanotube's nanoscale shape, are widely used in carrier and separation applications. The conjugation of CNTs with polysaccharide, proteins, drugs, and magnetic nanoparticles provides a chance for smart targeting and trajectory manipulation, which are used in the crucial field of life science applications, including for cancer disease diagnostics and treatments. Providing an optimal procedure for delivering a drug to a specific area based on mathematical criteria is key in systemic delivery design. Trajectory guidance and applied force control are the main parameters affected by systemic delivery. Moreover, a better understanding of the tissue parameters and cell membrane molecular behaviour are other factors that can be indirectly affected by the targeted delivery. Both sides are an essential part of successful targeting. The lung is one of the challenging organs for drug delivery inside the human body. It has a large surface area with a thin epithelium layer. A few severe diseases directly involve human lung cells, and optimal and successful drug delivery to the lung for the treatment procedure is vital. In this paper, we studied functionalized CNTs' targeted delivery via crossing through the lung cell membrane. Molecular dynamics (MD) software simulated all the interaction forces. Mathematical modelling of the cell membrane and proposed delivery system based on the relation of velocity and force has been considered. Dynamics equations for CNTs were defined in the time and frequency domain using control theory methods. The proposed delivery system consists of two main parts: crossing through the cell membrane and targeting inside the cell. For both steps, a mathematical model and a proper magnetic field profile have been proposed. The designed system provides criteria for crossing through the cell membrane within 30 s to 5 min and a translocation profile of 1 to 100 Å. [ABSTRACT FROM AUTHOR]