Use of high salinity water in a power plant by connecting a direct contact membrane distillation (DCMD) to a steam-injected gas turbine (STIG).

Unlike steam turbines, electricity production in gas turbines is inherently independent of freshwater consumption. However, the thermal efficiency of gas turbines decreases as the temperature of input air increases. As a result, many methods of cooling the inlet air require the use of fresh water. Moreover, when it comes to humid gas turbine technology, the practice of injecting steam or humid air into the turbine to improve its thermal efficiency and output power consumes a substantial amount of freshwater. Therefore, reducing the use of fresh water to enhance the output power and thermal efficiency of gas turbines can be a necessary option, especially in hot and dry regions. Alternatively, considering the significant amounts of waste heat in gas turbines, one solution to reduce fresh water consumption is to connect them to thermal desalination units. However, conventional thermal desalination is only practical for seawater desalination in coastal areas. Therefore, this study explores the possibility of linking a direct contact membrane distillation (DCMD) unit to a Steam-injected gas turbine (STIG), which can use high salinity water sources like reverse osmosis (RO) brine in inland regions. The freshwater generated by the DCMD is used to chill the input air to the compressor and produce steam injected within the turbine. Simulation results show that this connection can raise the net output power by [9 to 17.2] MW and thermal efficiency by [3.3 to 15.6] % for compressor pressure ratios between [5 to 30], when compared to a simple gas turbine.

Microalgal biofouling formation on tubular cellulose-ester membranes during dewatering by forward osmosis.

This work assesses the biofouling formation of a microalgal consortium, cultivated in wastewater, on dialysis tubular membranes with no supporting layer, in both batch and continuous FO dewatering modes. The biological adhesion strength was compared with the predictions from the Baier and Vogler biocompatibility theories, employing critical surface tension (γc) and water adhesion tension (τ0), respectively, as measurable parameters of surface wettability. The results indicate that most of the tested membranes presented amphiphilic surface characteristics (τ0=22 to 45 mJ.m-2, θW ≈ 65˚) with a minimal biological adhesion tendency, which is compatible with the Vogler criteria. However, the membrane exposed the longest time to the microalgal culture presented more hydrophobic characteristics and poor wettability. The existing thermodynamic models succeeded in predicting cell-cell and cell-surface interactions as a competitive phenomenon. Nevertheless, the XDLVO model was used to determine changes in the cell-to-surface attraction dynamics. This assessment of microalgal foulant-membrane interfacial interactions helps to enhance understanding of the fouling mechanisms present on a novel FO membrane surface.

Forward osmosis dewatering of seawater and pesticide contaminated effluents using the commercial fertilizers and zinc-nitrate blend draw solutions.

Fertilizer driven forward osmosis (FDFO) process would be feasible due to the possible prevention of the drainage of dewatered and concentrated pesticide effluent from agricultural pesticide industries to the environment. Instead, it would be possible to return the concentrated pesticide solution to the processing cycle, and on the other hand, employ directly the obtained diluted fertilizer draw solution for irrigation. This study investigated the performance of zinc-nitrate/amino-acids blends as fertilizer type draw solution, and distilled water, saline water (seawater), and synthetic wastewater containing pesticides as feed. The results indicated that the synergetic effect of blended type fertilizer presented significantly higher osmotic pressure and water flux than the sum of their individual ones, especially when the amount of amino acid increased. Conversely, an ignorable reverse flux of blended fertilizer draw solute was observed. The fertilizer blend with a molar ratio of 1:6 zinc-nitrate/amino-acid achieved the higher average fluxes of 34.7 and 23.92 L/m2h from distilled and saline waters compared to common draw solutions such as metal salts. Furthermore, the FDFO exhibited a high rejection (over 99%) of bentazon and imidacloprid in feed solutions compared to other agricultural pesticides due to their larger molecular weight and molecular size. The applied FDFO represented a significant reduction in specific energy consumption (from 0.17 to 0.049 kWh/m3) in a bench-scale setup as compared to the RO process almost at the same water permeation flux and the rejection of bentazon.

A mesoporous melamine/chitosan/activated carbon biocomposite: Preparation, characterization and its application for Ni (II) uptake via ion imprinting.

A novel imprinted biocomposite and its non-imprinted form were developed by melaminating and crosslinking of chitosan coated onto a bio-based activated carbon and characterized using FTIR, BET, FESEM-EDS and XRD. Nickel, 4-Toluenesulfonyl chloride, and glutaraldehyde were used as a template, converter of hydroxyl and amine groups to good leaving groups, and cross-linker, respectively. The factors affecting adsorptivity and imprinting factor were optimized by using the Taguchi method for the subsequent comparative adsorptivity, kinetics, isotherms, selectivity, and reusability studies of imprinted biocomposite with its non-imprinted one. The pseudo-first-order and Langmuir models were best fitted to the experimental kinetics and equilibrium isotherm data, respectively. The maximum Ni (II)) adsorptivity of 109.86 mg/g, the imprinting factor (I·F) of 5.45 and Ni (II) selectivity coefficients values of 3.13, 4.48, 3.72, 2.51 for Ni (II) toward Zn (II), Cd (II), Cu (II) and Pb (II), respectively, were obtained at optimum conditions. After five consecutive adsorption-desorption cycles, the biocomposites still presented a high adsorptivity (>83%), indicating their excellent reusability.

Fabrication and characterization of conductive polypyrrole/chitosan/collagen electrospun nanofiber scaffold for tissue engineering application.

Conductive electrospun nanofiber scaffold containing conductive polypyrrole (PPy) polymer was fabricated to accelerate healing of damaged tissues. In order to prepare these scaffolds, various weight percentages of polypyrrole (5, 10, 15, 20, 25%) relative to the polymers combination (chitosan, collagen, and polyethylene oxide) were used. The fabricated composite scaffolds were characterized using chemical, morphological, physio-mechanical, and biological analyses including; FTIR spectroscopy, SEM, electrical conductivity, tensile test, in vitro degradation, MTT Assay and cell culture. The polypyrrole particles were perfectly dispersed inside the nanofibers, and the fibers average diameter were reducing by increasing the polypyrrole content in the composites. The presence of polypyrrole in fibers enhanced their conductivity up to 164.274 × 10-3 s/m which is in the range of semi-conductive and conductive polymers. MTT and SEM analyses displayed that nanofibers composing 10% polypyrrole possess better cell adhesion, growth and proliferation properties comparing to other compositions. Furthermore, the suitable mechanical properties of scaffolds ideally fitted them for different kinds of tissue applications including skin, nerve, heart muscle, etc. Therefore, these fabricated conductive nanofiber scaffolds are particularly appropriate for employing in body parts with electrical signals such as cardiovascular, heart muscles, or nerves.

Fabrication and characterization of a novel compliant small-diameter PET/PU/PCL triad-hybrid vascular graft.

Nanomaterial structures are highly contributive in tissue engineering vascular scaffolds (TEVS) due to their ability to mimic the nanoscale dimension of the natural extracellular matrix (ECM) and the existing mechanical match between the native blood vessel and the scaffold as a vascular graft. The aim of this study was to develop and mechanically improve the nanofibrous triad-hybrid scaffolds with different composite ratios of polyethylene terephthalate (PET), polyurethane (PU), and polycaprolactone (PCL). The morphological, biological, mechanical, and biomechanical properties of the neat and hybrid structures were examined using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), tensile strength, compliance, burst pressure, MTT assay, and by implanting the specimens under rat skin to explore the immune system in vivo. The results showed that the fiber diameter and porosity changes in the triad-hybrid electrospun scaffold ranged within 388 ± 88 to 547 ± 89 nm and 56.60 ± 2.06% to 75.00 ± 1.94%, respectively. In addition, the changes in the tensile strength and force in the scaffolds were within the ranges 2.7 ± 0.44 to 5.27 ± 0.83 MPa and 2.68 ± 0.19 to 10.03 ± 0.75 MPa, respectively. Also, the compliance and burst pressure of the structures were reported as 4.05 ± 0.21 to 7.09 ± 0.49 and 1623 ± 329 to 2560 ± 121 mmHg, respectively. According to the MTT assay, high cell viability was observed on the triad-hybrid structures with a high percentage of PET when compared to that of PU. The findings of this research demonstrate that the PET/PU/PCL triad-hybrid vascular scaffold has enough potential to be used in vascular tissue engineering application.

The Role of Interleukin-4 and 13 Gene Polymorphisms in Allergic Rhinitis: A Case Control Study.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Small-diameter vascular graft using co-electrospun composite PCL/PU nanofibers.

Small-diameter vascular scaffolds have been developed by a co-electrospinning method using polyethylene terephthalate (PCL) and elastic polytetrafluoroethylene (PU) as biopolymers with long degradation time. Although they possess favorable properties, individually these two polymers do not meet the requirements for the production of synthetic vascular scaffolds. The co-electrospinning method was adopted to develop and mechanically improve the composite PCL/PU vascular scaffolds. The morphological, mechanical and biological properties of these vascular scaffolds were evaluated through scanning electron microscopy, differential scanning calorimetry, Fourier transform infrared spectroscopy, compliance, tensile testing and MTT assay. The in vivo study of the vascular scaffolds was performed by implanting them on rat and sheep models. The compliance of the composite vascular scaffolds improved by up to 43% through an increased percentage of PU from 10%-90%. The obtained UTS of the scaffolds at 10%, 25%, 50%, 75% and 90% of PU were 4.7 ± 0.34, 3.4 ± 0.6, 4.8 ± 0.62, 2.2 ± 0.34 and 4.4 ± 1.9 MPa, respectively. The results of MTT assays indicated that the cell growth on the scaffolds was augmented when compared to the control, from day one to day seven. Mild edema, mild foreign-body granulomatous reaction and mild fibrosis were observed by pathology test as the side effects in the composite scaffold with 50% PCL. Doppler ultrasound and angiography images confirm that no aneurysm, thrombogenesis, neointimal hyperplasia or occlusion exist, and there is complete patency at the end of an eight month investigation. The fabricated composite vascular scaffolds provide appropriate mechanical and biological properties and clinical requirements, indicating their required potential to be applied as a small-diameter vascular graft.

Engineering of oriented carbon nanotubes in composite materials.

The orientation and arrangement engineering of carbon nanotubes (CNTs) in composite structures is considered a challenging issue. In this regard, two groups of in situ and ex situ techniques have been developed. In the first, the arrangement is achieved during CNT growth, while in the latter, the CNTs are initially grown in random orientation and the arrangement is then achieved during the device integration process. As the ex situ techniques are free from growth restrictions and more flexible in terms of controlling the alignment and sorting of the CNTs, they are considered by some as the preferred technique for engineering of oriented CNTs. This review focuses on recent progress in the improvement of the orientation and alignment of CNTs in composite materials. Moreover, the advantages and disadvantages of the processes are discussed as well as their future outlook.

An experimental-numerical investigation on the effects of macroporous scaffold geometry on cell culture parameters.

INTRODUCTION: Perfused bioreactors have been demonstrated to be effective in the delivery of nutrients and in the removal of waste products to and from the interior of cell-populated three-dimensional scaffolds. In this paper, a perfused bioreactor hosting a macroporous scaffold provided with a channel is used to investigate transport phenomena and culture parameters on cell growth. METHODS: MG63 human osteosarcoma cells were seeded on macroporous poly​(ε-caprolactone) scaffolds provided with a channel. The scaffolds were cultured in a perfused bioreactor and in static conditions for 5 days. Cell viability and growth were assessed while the concentration of oxygen, glucose and lactate were measured. An in silico, multiphysics, numerical model was set up to study the fluid dynamics and the mass transport of the nutrients in the perfused bioreactor hosting different scaffold geometries. RESULTS: The experimental and numerical results indicated that the specific cell metabolic activity in scaffolds cultured under perfusion was 30% greater than scaffolds cultured under static conditions. In addition, the scaffold provided with a channel enabled the shear stress to be controlled, the initial seeding density to be retained, and adequate mass transport and waste removal. CONCLUSIONS: We show that the macroporous scaffold provided with a channel cultured in a macroscale bioreactor can be a robust reference experimental model system to systematically investigate and assess crucial culture parameters. We also show that such an experimental model system can be employed as a simplified "representative unit" to improve the performance of both perfused culture systems and hollow, fiber-integrated scaffolds for large-scale tissue engineering.