abdolreza samimi

The induced phase separation method was used to fabricate polyvinyl chloride (PVC) flat sheets for membrane distillation (MD) of RO brine feed by using dimethylformamide (DMF) and water as solvent and nonsolvent, respectively. Polyvinylpyrrolidone (PVP) and zinc oxide (ZnO) nanoparticles were utilized to improve the membrane structure and modify pore surfaces. The Taguchi experimental design approach was employed to investigate the impacts of concentrations of PVP and ZnO nanoparticles on the membrane's structural characteristics and performance. SEM, XRD, and FT-IR were used to characterize the surface and cross-sectional morphology, as well as the presence of crystalline phases and cross-linked organic groups, respectively. The water contact angle was measured to determine the wettability of the surface membrane and the impact of ZnO nanoparticles on its hydrophobicity. The membrane synthesis and MD process parameters were optimized for a Persian Gulf feed brine to obtain a maximum contact angle of 148°, under 80 °C and 12 L.min-1 circulating feed water, and resulted in high salt rejection (96.4%) and proper permeability water flux (4.2 L.m-2h-1).

The study investigated the modification of polyethersulfone (PES), polyvinylidene fluoride (PVDF), and polyacrylonitrile (PAN) hollow fiber membranes using a chitosan solution as the proton exchange membrane for microbial fuel cells (MFCs). Firstly, the performance of the modified PES membrane using 1, 2, and 3% of chitosan in 0.1 M acetic acid coating were inspected. Chitosan coating decreased the internal resistance and enhanced the electricity generation of the MFCs. The maximum power and current densities of 755.202 mW/m2, and 5525.42 mA/m2 were achieved for 3% chitosan-coated PES (PES-3%chi) compared to 629.533 mW/m2 and 3237.79 mA/m2 for pristine PES membrane. Thereafter, application of a 3% chitosan coating over the PAN and PVDF membranes exhibited excessive improvement in the bioelectricity generation and wastewater treatment efficiency of the MFCs. The PAN-3%chi achieved the uppermost power and current densities of 765.147 mW/m2 and 8297.46 mA/m2, which were 1.7 and 2.6 higher than the PAN membrane (450.675 mW/m2 and 3216.56 mA/m2). The electricity generation of the PVDF membrane was enhanced by 5.3 times (337.134 mW/m2 and 2720.16 mA/m2) after the addition of 3% chitosan, likely due to the improvement in hydrophilicity and proton conductivity. The COD removal efficiencies of 42.41, 40.55, and 36.11% were obtained by PAN-3%chi, PES-3%chi, and PVDF-3%chi membranes, respectively, which were 3.53, 4.01, and 5.53 times higher than the values obtained by their pristine unmodified samples.

This study evaluated the ability of Chlorella vulgaris, a freshwater microalgae species, to remove nutrients from raw municipal wastewater. The wastewater was collected from the initial sedimentation-stage discharge of the treatment plant and used to cultivate the microalgae in both a shaker-incubator and a photobioreactor. The results showed that the microalgae effectively reduced the nitrate, nitrite, phosphate, and ammonium ion concentrations in the wastewater by over 90%. Phosphate removal was particularly efficient in the photobioreactor, with a removal rate of 91%, while the shaker- incubator had a removal rate of 44%. In addition to removing nutrients, the microalgae were also able to significantly reduce the wastewater’s chemical oxygen demand (COD), with a reduction of over 90% from 264 to 23.1 mg/l. The microalgae also had a symbiotic effect on the bacterial colonies present in the wastewater, reducing their numbers by 99% while allowing the microalgae to thrive. The final biomass concentration in the photobioreactor was 2.03 g/l, a higher value compared to similar studies. These results demonstrate the potential of Chlorella vulgaris and other microalgae species for use in wastewater treatment systems.

The preparation of nanocomposite membranes containing Carbon NanoTubes (CNTs) has been one of the prevalent subjects for research. Despite drawing attention to studying it, these efforts were insufficient in comparison with its prospect as a new technology. The importance of using carbon nanotube membranes, especially in water treatment and desalination applications, has persuaded all countries to focus more and more on relevant research. In recent decades, carbon nanotubes membranes are a major branch in the field of membrane technologies because of the discovery of new properties of the CNTs in different conditions and various substrates, the effect of the CNTs orientation and the sorting on the nanocomposite properties, and new interactions with the pollutants and the salt molecules in the water purification process. In this area, new methods for synthesis, the use of novel materials and the clarification of the mechanisms are the most important issues that cause accessibility of cheaper, more flexible, and more efficient methods. The review consists of the preparation of polymeric nanocomposites containing the CNTs, mechanism, orientation, and arrangement methods of carbon nanotubes in membrane structure, as well as the recent application of these membranes for water treatment and desalination. The findings of this review might lead to more curiosity and investigation regarding the above matters.

In this investigation, fresh and regenerated Ni-W-Alumina-Zeolite industrial hydrocracking catalysts are characterized via several analyzing methods, including XRF, XRD, BET adsorption, FT-IR, FESEM-EDS, and TGA-DTA to understand the phenomena affecting trend towards their deactivation. The XRD patterns represented the presence of main phases of Al2O3/Y-zeolite as support and NiWO4/WO3 as active compounds. For the catalysts subjected to a three-year reactor operation/regeneration cycle, the XRF analysis revealed elemental enhancement of Fe, Na, V, Pb, Sb, and S, mostly from an outsourced environment. The BET and BJH analyses represented cylindrical shape mesoporosity for the samples, while the total pore-specific surface area and volume were reduced from 287.73 m2/g  and 0.46 cm3/g to 160.84 m2/g and 0.40 cm3/g for fresh and regenerated samples, respectively. The latter results indicated possibly filling the pores with impurities and/or sintering of pores. By considering FESEM images, the smooth surface of the fresh sample and indented/corroded characteristics of the regenerated one were seen. The variety of analyses portrayed the increasing trend of the poisoning factors and the structural malfunction of the catalysts towards irreversible deactivation.

Recently, using volumetric receivers as a novel idea to collect solar energy was considered. Solar radiation volumetrically absorbers with a heat transfer fluid which flows through a transparent tube. Nanofluids as working fluids were proposed by different researchers because of their interesting absorption coefficient as well as an important heat transfer coefficient. However, conditions such as the severe temperature gradient in absorber tubes and high temperature of working heat transfer fluid, deteriorate stability of the nanofluids. Considering the kinetic energy of nanoparticles, DLVO potential energy and steric repulsion between nanoparticles, a molecular approach is adopted to investigate the nanofluid stability for different nanofluids with polymeric surfactants and different operational conditions. Two types of polymeric surfactants were considered and stability diagrams introduced to show the conditions for which a nanofluid would be stable. In the case of using PAA for a given temperature gradient, increasing the working fluid temperature required smaller nanoparticle diameters to result in a stable nanofluid (nanoparticles up to 13.2 nm diameter) and for PMAA, a stable nanofluid can be achieved with larger nanoparticle diameters (about 80nm) while increasing the working fluid temperature.

The present study provides a novel process flowsheet for CO2 compression and purification unit (CPU) in order to improve its product quality and control performance. Unlike the previous process flowsheet, the number of cold-boxes has been reduced to one, which in turn decreases investment costs and improves energy integration. The performance of the proposed flowsheet was compared with two recently suggested ones for a given feed. The results showed that, compared with the other process flowsheet, the new one not only can operate at lower operating pressure but also needs a significantly smaller heat-transfer area. Also, the dynamic behavior and controllability of the proposed process flowsheet are analyzed to ensure proper functioning. The control loops used in the new flowsheet were simpler than those used in the previous flowsheet, and controllability was achieved using proportional (P) and Proportional-Integral (PI) controllers, which offers a performance advantage over the other process flowsheet. Using step changes, the effects of disturbances in feed temperature, flow rate, and composition on the final product specifications were also investigated. The proposed flowsheet process proved to be robust against the disturbances, and the control structure was able to handle them appropriately. The proposed process flowsheet was also able to maintain purity and recovery rates of 96.74% and 90.08%, respectively, in the face of disturbance.

.The artery diseases such as the coronary arteries are of the important cardiovascular diseases. The autograft as a common surgical is the main treatment for this problem, but in many patients, the autografts are not. So, due to a large number of requirements, it needs to find suitable replacements for diseases of blood vessels. Tissue engineering at the nanoscale level is a promising approach to the design and fabrication of artificial blood vessels. Nanomaterial structures are highly contributive in tissue engineering vascular scaffolds (TEVS) due to their ability in mimicking the nanoscale dimension of the natural extracellular matrix (ECM) and the existing mechanical match between the native vessel and the scaffold. The aim of this research was developing and mechanically improving nano-fibrous composite scaffolds using blend electrospinning methods with different ratios of the polyethylene terephthalate (PET), polyurethane (PU) and polycaprolactone (PCL). The morphological and mechanical properties all structures were evaluated using SEM, FTIR and tensile properties. The neat and composite structures were completely intact with randomly oriented fibers and without any beads. Results showed that the average fiber diameter, porosity, stress and Young’s modulus changes’ range in composite structures (PCL/PU and PET/PU) obtained 343 ± 94 to 382 ± 83 nm, 58.6 ± 3.12 to 81 ± 1.7 %, 2.66 ± 0.39 to 19.05 ± 3.2 MPa and 3.18 ± 0.09 to 41.4± 3.31 MPa, respectively. The fabricated scaffolds and especially PET/PU structure exhibited suitable mechanical and biological properties and clinical requirements as a small-diameter vascular graft.

One of the main causes of urinary infections is the use of urinary catheters. Over time, the overuse of chemical antibiotics has made urinary bacteria become resistant to chemical antibiotic treatments. Therefore, the major challenge in hospitals is preventing urinary infection and finding a suitable replacement for chemical antibiotics.  In recent years, researchers have been studying the use of herbal medicines to replace antibiotics.

In this study, green tea and ziziphora herbal extracts have been used as antibacterial agents for making silicone coated latex Foley catheters antibacterial and antibiofilm agents with inoculation. Various tests such as disc diffusion, broth penetration, contact angle, FE-SEM, AFM, ATR-FTIR, and elasticity were performed.

After inoculation, disc diffusion test was performed on Staphylococcus aureus and Escherichia coli, urinary infection agents, and the antibacterial property of the silicone coated latex catheters was verified. In the penetration broth test, the herbal antibacterial catheters could eliminate the bacteria after 21 days (P˂0.0001). The contact angle test showed an increase in the hydrophilic property of the modified catheter (p˂0.0002). The mechanical test suggests an increase in Young module. SEM test indicates a decrease in bacteria adherence to the catheter surface. AFM test shows an increase in the roughness of the surface after impregnation. The presence of extracts in catheters was verified by ATR-FTIR.

It can be said from the obtained results that medicinal herbs can be appropriate agents for the inoculation of urinary catheters and the reduction of urinary infections in hospitals. In fact, modified catheters with herbal extracts could eliminate all bacteria. In addition, herbal extracts could be a good replacement for chemical antibiotics. Finally, herbal extracts could increase surface hydrophilicity,   prevent bacteria adherence, and they have antibiofilm properties.

Although bentazon is widely used as an agricultural herbicide, it is harmful to humans and poses many environmental threats. This study focused on the treatment of wastewater contaminated with bentazon pesticides using membrane technology. In this regard, low-pressure reverse osmosis (RO) was employed as it has already been used in the removal of other micro-pollutants. The effects of process variables on water flux and bentazon rejection were studied: temperature, pressure, and bentazon feed concentration. Based on central composite design (CCD), the quadratic model was engaged to correlate the process variables with the water flux and the bentazon removal responses. The obtained results showed that the bentazon rejection increased by enhancing the pressure while it decreased at higher feed solution concentration. However, with increasing temperature, the amount of bentazon removal was reduced. A bentazon rejection efficiency of 100 % could be achieved under optimum conditions (i.e., the temperature of 29.8 ℃ and hydrostatic pressure of 12.6 bar for a feed solution concentration of 66.9 mg/L). Therefore, reverse osmosis can effectively remove bentazon.

The removal of formaldehyde from contaminated air was investigated via three laboratory-scale biofilters packed with different materials: a mixture of compost and woodchips (І), the natural clinoptilolite zeolite particles in the original form (II), and the mixture of zeolite/activated carbon (III). The biofilters were inoculated using aerobic sludge. The average removal efficiencies of 97.5%, 90%, and 93.5% were obtained at a 100 s empty bed residence time (EBRT) and 20 mg/m3 inlet concentration of formaldehyde for the biofilter of configurations І, II, and III, respectively. Also, the performance of the reactors was investigated at different EBRTs of 20, 30, 60, and 100 s, and the maximum elimination capacity of 2840 mg/m3.h was achieved at the lowest EBRT (20 s) for the biofilter of configuration II. Increasing the inlet formaldehyde concentration from 20 mg/m3 to 80 mg/m3 led to the maximum formaldehyde removal efficiency of 82% for the biofilter of configuration III. Therefore, a comparison of the results of the biofilters' performances showed that the biofilter of configuration III had the best performance, which was validated by obtaining a higher mass transfer coefficient. However, the biofilter of configurations II and III achieved steady-state conditions in a shorter time.

This work, the application of a surfactant-modified natural nano-clinoptilolite for the removal of several two valances heavy metal cations (i.e., Cu2+, Pb2+, Ni2+, Cd2+, Fe2+ and Zn2+) from aqueous media was discussed. Triton X-100 was used as modifier and to achieve maximum efficiency of adsorption; variables such as the concentration of surfactant, contact time, the working temperature and pH of sample solution were optimized. The results revealed that, the maximum adsorption was achieved at a solution with the pH of 6, containing 2 mL of triton X-100 and 2 g/L of clinoptilolite at 45 °C. The obtained selectivity series for the adsorption of cations were Pb2+>Cu2+>Cd2+>Ni2+ >Zn2+>Fe2+. The maximum adsorption capacity of the modified zeolite for Pb2+, Cu2+, Cd2+, Ni2+, Zn2+ and Fe2+ was 91.34, 85.71, 78.27, 76.18, 67.41 and 63.45 mg/g, respectively. The adsorption data were acceptably fitted to the both Freundlich and Langmuir isotherms.

Graphical size distribution is widely used in different fields of science and studies related to powders, droplets, bubbles, and pores. However, in some condition it may also be necessary to express the size distribution quantitatively. In spite of there being several suggested ways to quantify size distribution in the literature, some of these approaches are not applicable for many methods and the rest have other drawbacks. In this study, first, some quantitative size distribution methods (such as the polydispersity index) and their defects are concisely discussed. SPAN seems to be the most generally appropriate method, its parameters are determined from cumulative size distribution data. Nevertheless, some specific results imply that there are still some drawbacks in this method. Next, a new quantitative description of size distribution is presented which is applicable to many different techniques. In this method the characterization value is limited to 0 and 1, where 0 is related to completely polydispersed size distribution and 1 denotes the completely monodispersed size distribution.

Allergic Rhinitis (AR) is an IgE-mediated inflammatory disorder with high morbidity rates. The eitiology of this disease is understood to occur from a complex interaction between genetic and environmental factors. T helper type 2 cells have been shown to have a crucial role in atopic disease due to their production of the cytokines, intelukin (IL)-13 and IL-4, involved in inflammation. Research has shown single nucleotide polymorphisms (SNP) of the IL-13 and IL-4 genes to be associated increased levels of IgE and with allergic diseases such as, allergic rhinitis, asthma, and atopic dermatitis. Specifically, the rs2243250 SNP of IL-4 and the rs20541 SNP of IL-13 have been shown to be associated with AR.

A case-control study was designed to investigate the relationship between the two SNPs rs2243250 and rs20541 with the incidence of AR. The SNPs were examined in patients with AR and healthy controls (86 patients and 86 controls). Blood samples were collected and DNA was extracted to evaluate the SNPs by RFLP-PCR.

Recessive analysis model of the IL-13 gene (GG vs. AA+AG) revealed that the GG genotype was more common in AR patients (P=0.36) )OR=0.8 [81% CI 0.38-1.6]). For the IL-4 gene (TC vs. TT+CC), the TC genotype was more common in AR patients (P = 0.0022)) OR=0.71 [60% CI 1.41-5.02]). Furthermore, in the IL-4 gene, the 590 T>C polymorphism had a significant association with AR. However, no association was found between AR and the IL-13 rs20541 polymorphism.

Our findings suggest that the IL-13 polymorphism (rs20541, Exo 4, G>A, Arg130Gln) and IL-4 polymorphism (rs2243250= C-590T, promoter, T>C) are co-associated with AR and sensitivity to aeroallergens. However, this study used a cohort of AR patients and healthy controls from the northeast of Iran. Given the influence of ethnicity and environment on genetics, further investigation is needed to elucidate the role of SNPs in IL-4 and IL-13 in AR among different populations.

The effect of the thickness of ceramic membrane on the productivity of microbial fuel cells (MFCs) was investigated with respect to the electricity generation and domestic wastewater treatment efficiencies. The thickest ceramic membrane (9 mm) gained the highest coulombic efficiency (27.58±4.2 %), voltage (681.15±33.1 mV), and current and power densities (447.11±21.37 mA/m2, 63.82±10.42 mW/m2) compared to the 6- and 3-mm thick separators. The results of electrochemical impedance spectroscopy (EIS) analysis were investigated to identify the internal resistance constituents by proposing the appropriate equivalent electrical circuit. The Gerischer element was modeled as the coupled reaction, and diffusion in the porous carbon electrodes and the constant phase element was assimilated into the electrical double-layer capacitance. The thickest ceramic (9 mm) was found to have the largest ohmic resistance; however, owing to its superior barrier capability, it provided more anoxic conditions for better accommodation of exoelectrogenic bacteria in the anode chamber. Therefore, lower charge transfer, fewer diffusional impedances, and higher rates of anodic reactions were achieved. Excessive oxygen and substrate crossover through the thinner ceramics (of 6 and 3 mm) resulted in the suppressed development of anaerobic anodic biofilm and the accomplishment of aerobic substrate respiration without electricity generation.

Nanoporous anodic aluminum oxide (AAO) has been used in many different fields of science and technology, due to its great structural characteristics. Solar selective surface is an important application of this type porous material. This paper investigates the effect of nanoporous AAO properties, including; film thickness, pore area percentage and pore diameter, on absorption spectra in the range of solar radiation. The parameters were verified individually depending on anodization condition, and the absorption spectra were characterized using spectrophotometer analysis. The results showed that the absorptivity was increased with growth of the film thickness. Furthermore, increasing the pore diameter shifted the absorption spectra to the right range, and vice versa. The investigation revealed the presence of an optimum pore area percentage around 14% in which the absorptivity was at its maximum value.

The Degree of Deacetylation (DD) of chitosan plays a main role in its physical, chemical and biological properties. Hence, in this study, low-viscous, medium, and high (impure and improved) molecular weight chitosan were used to determine DD, using a simple and exact method, The DDs of chitosan were determined by the fourier transform infrared spectroscopy (Baseline-a and b) and linear potentiometric titration. Thie concluded results were compared using Root-Mean-Square Deviation (sRMSD) whereby an agreement between the linear potentiometric titration and fourier transform infrared spectroscopy (Baseline-a) were shown. In presented method, for purifying impurities and improving DD of the high molecular chitosan, DD was noticeably increased from 60.1 to 92.7 %. The analysis of chitosan's DD represented the raise of DD in the presence of the increase of viscosity and molecular weight of chitosan.

Alginate and chitosan nanoparticles were prepared using a new reverse micelle system, composed of cetyltrimethylammonium bromide (CTAB) as a surfactant, isooctane as a solvent, and 1-hexananol as a co-solvent. The obtained nanoparticles were characterized by FTIR, DLS and TEM techniques. The main objective of this study was to investigate the effects of polymer concentration, water content, and volumetric ratio of co-solvent to solvent on the physical and morphological properties of the prepared nanoparticles. To evaluate the results, the design of experimental was initially carried out and then the obtained data were statistically analyzed using the Qualitek-4® software. Results revealed that the size of the prepared alginate and chitosan nanoparticles varied in the range 220–490 and 210–1,050 nm, respectively. Furthermore, increasing either alginate or chitosan concentration increased the size of their nanoparticles. The results also showed that the size of nanoparticles was decreased with increasing the volumetric ratio of co-solvent/solvent. Finally, the size of alginate nanoparticles was increased by increasing the water content while it decreased the size of chitosan nanoparticles. Considering the statistical analysis of experiments, the polymer concentration is the major parameter affecting nanoparticles’ size. In contrast, water content has the smallest effect on the size of nanoparticles. However, the difference between the particle sizes of chitosan and alginate nanoparticles cab be attributed to the electrostatic repulsion between chitosan and CTAB.

Gas–solid fluidized bed reactors have many industrial applications. Hydrodynamics of these systems requires more investigation due to their complexity of behaviors. In this study, the 2D hydrodynamics of fluidized bed containing 275 μm spherical glass beads was investigated by using CFD analysis. The simulation of fluidized bed, carried out using the two-fluid model combined with kinetic theory of granular flow for description of rheology of solid phase as a pseudo fluid. Whilst the superficial gas velocity were set on the range of 0.1–0.46 m/s. For the system of dense gas-solid fluidized bed, an algebraic granular energy-balance equation is proposed for determining the granular temperature instead of solving the full granular energy balance equation. This simplification does not lead to different results, but significantly reduces the computational effort of the simulation. The CFD simulation results were qualitatively and quantitatively compared with the literature. These comparisons show the good agreement between them. Particles velocity and volume fraction profiles predicted by CFD code were studied to increase insight of the transport phenomena and some physical phenomena such as particles erosion in these systems.