Direct synthesis of bi-modal porous structure MCM-41 and its application in CO2 capturing through amine-grafting

A bi-modal porous structure MCM-41 (BPS-MCM-41) was synthesized and functionalized by 3-[2-(2-Aminoethylamino)ethylamino]propyltrimethoxysilane (TRI); also, its performance in amine grafting and CO₂ capturing was compared with that of pore-expanded MCM-41 [1]. To create larger pores beside the mesoporous structure of MCM-41, carbon black nanoparticles were used as the solid template. Characterizing the BPS-MCM-41 using the BET and BJH techniques resulted in the surface reduction of 29.3 percent and volume increase of 68.46 percent. The pore size distribution showed two peaks: a narrow peak at 2.24 nm diameter, which belonged to micelles, and a wide one at about 50 nm due to the presence of used nanoparticles. The functionalization confirmed that BPS-MCM-41 is capable of accommodating a large quantity of amine groups. The CO₂ adsorption measurement indicated that internal volume of the adsorbent was a critical factor affecting the adsorption capacity of the amine grafted adsorbents.     

Statistical analysis and optimization of simultaneous biological nutrients removal process in an intermittently aerated SBR

Simultaneous removal of carbon and nutrients from a synthetic wastewater in aerobic/anoxic sequence batch reactor (SBR) was investigated. The experiments were conducted based on a central composite design (CCD) and analyzed using response surface methodology (RSM). Two significant independent variables, cycle time and aeration time, were studied to analyze the process. Five dependent parameters—total COD (TCOD) removal, total nitrogen removal, total phosphorus removal, total Kjeldahl nitrogen removal and effluent nitrate concentration—were monitored as the process responses. The region of exploration for the process was taken as the area enclosed by cycle times (2, 4.25 and 6.5 h) and aeration times (30, 40 and 50 min/h) boundaries. The maximum COD (87.18%) and TKN (78.94%) removal efficiencies were obtained at the cycle time and aeration time of 6.5 h and 50 min/h, respectively. While the maximum TN (71.15%) and phosphorus (68.91%) removal efficiencies were obtained at cycle time of 6.5 h and aeration time of 40min/h. As a result, high cycle time (6.5 h) and moderate aeration time (40min/h) were found to be the optimal region for maximum carbon and nitrogen removal efficiencies.     

CFD Simulation of Deep-Bed Paddy Drying Process and Performance

Computational Fluid Dynamics (CFD) was applied three-dimensionally to simulate the drying behavior of paddy in a deep-bed dryer. The commercial CFD software Fluent 6.3.26 was used. The deep-bed paddy drying process and performance were studied by incorporating user-defined function (UDF) in Fluent written in C language. The predicted drying parameters were compared with experimental data of deep-bed drying of paddy. The values of mean relative deviation (MRD), standard error of prediction (SEP), and maximum error of prediction (MEP) for prediction of grain moisture content, air temperature, and absolute humidity were less than 6, 10, and 9%; 0.33% (d.b), 1.24°C, and 0.06% (kg/kg of dry air); and 2.25% (d.b), 6.8°C, and 0.37% (kg/kg of dry air), respectively, which reflect reasonable accuracy. Moreover, the energetic and exergetic performance of deep-bed paddy drying were simulated and analyzed. The effects of inlet air temperature and mass flow rate on the performance parameters were investigated. It was shown that the application of higher levels of inlet air temperature and lower mass flow rates yielded higher exergy efficiencies of deep-bed paddy drying.     

Cell Membrane-Cloaked Nanotherapeutics for Targeted Drug Delivery

Cell membrane cloaking technique is bioinspired nanotechnology that takes advantage of naturally derived design cues for surface modification of nanoparticles. Unlike modification with synthetic materials, cell membranes can replicate complex physicochemical properties and biomimetic functions of the parent cell source. This technique indeed has the potential to greatly augment existing nanotherapeutic platforms. Here, we provide a comprehensive overview of engineered cell membrane-based nanotherapeutics for targeted drug delivery and biomedical applications and discuss the challenges and opportunities of cell membrane cloaking techniques for clinical translation.     

Bioactive Peptides: Synthesis,Sources, Applications,and Proposed Mechanisms of Action

Bioactive peptides are a group of biological molecules that are normally buried in the structure of parent proteins and become active after the cleavage of the proteins. Another group of peptides is actively produced and found in many microorganisms and the body of organisms. Today, many groups of bioactive peptides have been marketed chemically or recombinantly. This article reviews the various production methods and sources of these important/ubiquitous and useful biomolecules. Their applications, such as antimicrobial, antihypertensive, antioxidant activities, blood-lipid-lowering effect, opioid role, antiobesity, ability to bind minerals, antidiabetic, and antiaging effects, will be explored. The types of pathways proposed for bioactive applications will be in the next part of the article, and at the end, the future perspectives of bioactive peptides will be reviewed. Reading this article is recommended for researchers interested in various fields of physiology, microbiology, biochemistry, and nanotechnology and food industry professionals.     

Hydrodynamic and heat transfer properties of magnetic fluid in porous medium considering nanoparticle shapes and magnetic field-dependent viscosity

The purpose of this paper is to study the characteristics of the combined convection heat transfer and a micropolar nanofluid flow passing through an impermeable stretching sheet in a porous medium. The nanofluid flow field is affected by a magnetic field perpendicular to the sheet. The dynamic viscosity of the micropolar nanofluid changes under the influence of the magnetic field. The continuity, linear momentum, angular momentum, and energy equations are first simplified using the order of magnitude technique that, along with the applied boundary conditions and the definition of the appropriate parameters, are transferred to the similarity space using the similarity analysis. Then the resulting equations are solved using the Runge–Kutta method.The distinction of the macroscale and microscale flow fields and temperature fields resulting from different nanoparticle shapes was clarified. Increasing the Hartmann number, the vortex viscosity parameter, the magnetic parameter, the nanoparticle volume fraction, and the permeability parameter of the porous media increased the surface friction on the sheet. Increasing the vortex viscosity parameter, the magnetic parameter, and the volume fraction of the nanoparticles increases the Nusselt number.     

CFD study of non-premixed swirling burners: Effect of turbulence models

This research investigates a numerical simulation of swirling turbulent non-premixed combustion. The effects on the combustion characteristics are examined with three turbulence models: namely as the Reynolds stress model, spectral turbulence analysis and Re-Normalization Group. In addition, the P-1 and discrete ordinate (DO) models are used to simulate the radiative heat transfer in this model. The governing equations associated with the required boundary conditions are solved using the numerical model. The accuracy of this model is validated with the published experimental data and the comparison elucidates that there is a reasonable agreement between the obtained values from this model and the corresponding experimental quantities. Among different models proposed in this research, the Reynolds stress model with the Probability Density Function (PDF) approach is more accurate (nearly up to 50%) than other turbulent models for a swirling flow field. Regarding the effect of radiative heat transfer model, it is observed that the discrete ordinate model is more precise than the P-1 model in anticipating the experimental behavior. This model is able to simulate the subcritical nature of the isothermal flow as well as the size and shape of the internal recirculation induced by the swirl due to combustion.     

Effects of porous material on transient natural convection heat transfer of nano-fluids inside a triangular chamber

This study numerically investigates the impact of porous materials, nano-particle types, and their concentrations on transient natural convection heat transfer of nano-fluid inside a porous chamber with a triangular section. The governing equations of the two-phase mixture model are separated on the computational domain and solved using the Finite Volume Method, taking into account the Darcy–Brinkman model for porous medium. It was observed that convection heat transfer inside the triangular chamber consists of three stages named initial, transient, and semi-steady. The features of each step are provided in detail. The results suggested that the use of a hybrid nano-fluid(water/aluminum oxide-cooper) inside a porous glass material and an increase in volume fraction of nano-particles have adverse effects on heat transfer rate. In contrast, as the nano-particle volume fraction of the single nano-fluid(water/aluminum oxide) inside the chamber increased, convection heat transfer rate improved. At the same time, it was observed that the use of both nano-fluids(single and hybrid) in the porous environment of the aluminum foam could improve convection.     

Evaluation of Fracture Mechanisms in Al-Si Metal Matrix Nanocomposites Produced by Three Methods of Gravity Sand Casting,Squeeze Casting and Compo Casting in Semi-Solid State

Silicon - Magnetic stirring is considered to be the most useful stirring method in semi-solid casting processes which doesn’t have the restrictions of the mechanical stirring. In this...     

Flame synthesis of carbon nanofibers on carbon paper: Physicochemical characterization and application as catalyst support for methanol oxidation

We developed a simple, rapid and highly efficient flame synthesis method for direct growing carbon nanofibers (CNFs) on carbon paper (CP) using a common laboratory ethanol flame as both heat and carbon sources. High density CNFs with tangled solid-cored structure were uniformly formed over the Ni-plated CP surface in ∼20 s. The morphologies of the CNFs were characterized by scanning electron microscopy and transmission electron microscopy. X-ray diffraction study revealed the graphitic nature of the CNFs. Raman spectroscopy analysis confirmed that the CNFs are disordered graphitic nanocrystallites with high degree of exposed edges. Electrochemical impedance spectroscopy and cyclic voltammetry were used to show that growing CNFs directly on CP facilitates electron transfer with concomitant increase in double-layer capacitance. The CNF/CP was used as support for Pt nanoparticles to study their supporting effect on the catalyst performance. The as prepared Pt/CNF electrocatalyst exhibited much improved electrocatalytic activity for methanol oxidation compared to Pt/CP and commercial Pt/C on CP. High electronic conductivity and improved electrochemical behavior of the CNF/CPs, resulted from direct contact of the nanofibers with CP, combined with unique properties of CNFs, make the synthesized CNF/CPs promising for fuel cell applications.