Enhancement of simultaneous hydrogen production and methanol synthesis in thermally coupled double-membrane reactor

Coupling the methanol synthesis with the dehydrogenation of cyclohexane to benzene in a co-current flow, catalytic fixed-bed double-membrane reactor configuration in order to simultaneous pure hydrogen and methanol production was considered theoretically. The thermally coupled double-membrane reactor (TCDMR) consists of two Pd/Ag membranes, one for separation of pure hydrogen from endothermic side and another one for permeation of hydrogen from feed synthesis gas side (inner tube) into exothermic side. A steady-state heterogeneous model is developed to analyze the operation of the coupled methanol synthesis. The proposed model has been used to compare the performance of a TCDMR with conventional reactor (CR) and thermally coupled membrane reactor (TCMR) at identical process conditions. This comparison shows that TCDMR in addition to possessing advantages of a TCMR has a more favorable profile of temperature and increased productivity compared with other reactors. The influence of some operating variables is investigated on hydrogen and methanol yields. The results suggest that utilizing of this reactor could be feasible and beneficial. Experimental proof of concept is needed to establish the validity and safe operation of the recuperative reactor.     

Performance Evaluation of ANN and ANFIS Models for Estimating Garlic Crop Evapotranspiration

Estimation of evapotranspiration (ET) is necessary in water resources management, farm irrigation scheduling, and environmental assessment. Hence, in practical hydrology, it is often necessary to reliably and consistently estimate evapotranspiration. In this study, two artificial intelligence (AI) techniques, including artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS), were used to compute garlic crop water requirements. Various architectures and input combinations of the models were compared for modeling garlic crop evapotranspiration. A case study in a semiarid region located in Hamedan Province in Iran was conducted with lysimeter measurements and weather daily data, including maximum temperature, minimum temperature, maximum relative humidity, minimum relative humidity, wind speed, and solar radiation during 2008–2009. Both ANN and ANFIS models produced reasonable results. The ANN, with 6-6-1 architecture, presented a superior ability to estimate garlic crop evapotranspiration. The estimates of the ANN and ANFIS models were compared with the garlic crop evapotranspiration (ETc) values measured by lysimeter and those of the crop coefficient approach. Based on these comparisons, it can be concluded that the ANN and ANFIS techniques are suitable for simulation of ETc.     

High temperature water gas shift reaction over promoted iron based catalysts prepared by pyrolysis method

In this work the effects of different promoters (Cr, Al, Mn, Ce, Ni, Co and Cu) on the structural and catalytic properties of Nanocrystalline iron based catalysts for high temperature water gas shift reaction were investigated. The catalysts were prepared in active phase (Fe₃O₄) via a facile direct synthesis routs without any additive and characterized using X-ray diffraction (XRD), N₂ adsorption (BET), temperature-programmed reduction (TPR), transmission and scanning electron microscopies (TEM,SEM) techniques. The obtained results indicated that synergic effect of Mn and Ni promoters can lead to obtain a Cr-free catalyst with high activity. In addition, the effect of Ni content on the structural and catalytic properties of the Fe–Mn–Ni catalysts was investigated. It was found that Fe–Mn–Ni catalyst with Fe/Mn = 10 and Fe/Ni = 5 weight ratios showed the highest catalytic activity among the prepared catalysts and possessed a stable catalytic performance without any decrease during 10 h time on stream. Moreover, the effect of GHSV and steam/gas ratio on the catalytic performance of this catalyst was investigated.     

Effect of Al on the hydrogenation characteristics of nanocrystalline Mg powder

We have fabricated nanocrystalline Mg–Al powders with nominal Al compositions of 4 and 8 at% by the electrodeposition technique and have compared their hydrogenation characteristics with those for a commercially available pure Mg powder. It is elucidated that interestingly the amount of Al incorporated in MgH₂ increases with decreasing the hydrogenation temperature. This observation indicates that the magnesium hydride phase has a limited solubility for aluminum and the supersaturation of hydride with Al is attributed to the slower mobility of aluminum at low temperatures. The rejection of Al during hydride formation is shown to result in a higher fraction of the intermetallic phase, thus reducing the hydrogen capacity. It is suggested that the presence of the intermetallic phase prior to hydrogenation enhances the hydride nucleation rate, which further decreases the hydrogen capacity in comparison to pure Mg.     

Harnessing Normal and Engineered Mesenchymal Stem Cells Derived Exosomes for Cancer Therapy: Opportunity and Challenges

There remains a vital necessity for new therapeutic approaches to combat metastatic cancers, which cause globally over 8 million deaths per year. Mesenchymal stem cells (MSCs) display aptitude as new therapeutic choices for cancer treatment. Exosomes, the most important mediator of MSCs, regulate tumor progression. The potential of harnessing exosomes from MSCs (MSCs-Exo) in cancer therapy is now being documented. MSCs-Exo can promote tumor progression by affecting tumor growth, metastasis, immunity, angiogenesis, and drug resistance. However, contradictory evidence has suggested that MSCs-Exo suppress tumors through several mechanisms. Therefore, the exact association between MSCs-Exo and tumors remains controversial. Accordingly, the applications of MSCs-Exo as novel drug delivery systems and standalone therapeutics are being extensively explored. In addition, engineering MSCs-Exo for targeting tumor cells has opened a new avenue for improving the efficiency of antitumor therapy. However, effective implementation in the clinical trials will need the establishment of standards for MSCs-Exo isolation and characterization as well as loading and engineering methods. The studies outlined in this review highlight the pivotal roles of MSCs-Exo in tumor progression and the promising potential of MSCs-Exo as therapeutic drug delivery vehicles for cancer treatment.     

Optimization-based design of sliding sector control for active seismic protection of structures

The active tuned mass damper (ATMD) is a reliable energy-dissipating device to effectively protect structures from serious damages due to earthquake excitations. This study proposes the optimal design of sliding sector control (SSC) for the seismic protection of an 11-story shear building structure equipped with ATMD. First, the SSC controller is optimally designed for the seismic control of the structure subjected to an artificial earthquake. Then, the effectiveness of the optimized SSC (OSSC) is assessed in reducing the seismic responses of the structure subjected to four near- and far-fault earthquake excitations. The efficient performance of the OSSC technique is also validated and compared with that of a number of the control techniques such as linear quadratic regulator (LQR), fuzzy logic control (FLC), proportional-integral-derivative (PID), and optimal sliding mode control (OSMC). Comparative results demonstrate the efficiency and robustness of the proposed OSSC in comparison with those of the other controllers.     

Characteristics of heat insulating clay bricks made from zeolite,waste steel slag and expanded perlite

In order to lessen the energy loss of buildings during the operation phase, and also considering the importance of sustainable construction, producing bricks having more desirable thermal characteristics has become essential. In this study, insulation bricks composed of expanded perlite (EP), natural zeolite, ground granulated blast furnace slag (GGBFS) and clay were fabricated. The effect of replacing clay with GGBFS, zeolite and EP in amounts up to 15%, 15%, and 50% respectively on the bricks' properties was investigated. Mix proportion parameters of bricks were analyzed using the Taguchi method. Various properties of bricks including density, weight loss, shrinkage, apparent porosity, water absorption, resistance to freezing and thawing, compressive strength, thermal conductivity, and microstructural analysis of fired bricks were examined and compared against standard requirements for bricks. Overall, the results showed that while satisfying the standard requirements, bricks containing the aforementioned additives had lower thermal conductivity compared to normal bricks, and therefore, they could be utilized as heat insulation materials.