Stabilization of [BMIM][PF6] ionic liquid membrane in structurally optimized multilayer ceramic support through aqueous DEA solution for CO2/CH4 separation

Hamid Reza Mahdavi,Mehran Arzani,Hamed Faramarzi,Omid Bakhtiari,Toraj Mohammadi 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.127 No.-

The stability of the ceramic supported liquid membranes (SLMs) is one of the most interesting researchsubjects. In this work, the SLMs’ stability for CO2/CH4 separation was investigated. Following pressing a-Al2O3 substrates at 400, 600, and 800 bar, colloidal and polymeric TiO2 intermediate and top layers werecoated. Aqueous diethanolamine (DEA) solution was used as solvent in the SLM to optimize supportstructure based on CO2/CH4 separation performance. The pressed support at 800 bar and coated withTiO2 demonstrated best performance and selected for further study. Subsequently, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) ionic liquid (IL) was immobilized inside theselected support and used as the supported ionic liquid membrane (SILM) for CO2/CH4 separation. TheSILM separation performance was evaluated under different pressures and temperatures. Temperaturewas found to has greater effect than pressure due to a decrease in IL’s viscosity and an increase in penetrantdiffusivity. At 25 C and 1 bar, SILM exhibited consistent and reliable performance as CO2 and CH4permeabilities of 244.0 and 7.4 Barrer, respectively, and CO2/CH4 selectivity of 33.0 over 6 h. The findingscontribute to understanding the implementation of multilayer ceramic SILMs for CO2/CH4 separation andhighlight its potential along with opening up new avenues.

Intrathecal injection of magnesium sulfate: shivering prevention during cesarean section: a randomized, double-blinded, controlled study

Seyed Hamid Reza Faiz,Poupak Rahimzadeh,Farnad Imani,Ali Bakhtiari 대한마취통증의학회 2013 Korean Journal of Anesthesiology Vol.65 No.4

Background: Regional anesthesia is known to significantly impair thermoregulation and predispose patients to hypothermia. We hypothesized that the addition of an intrathecal injection of magnesium sulfate (MgSO4) to bupivacaine would improve perioperative shivering in female patients undergoing elective caesarean section. Methods: In a block-randomized, double-blinded, controlled trial 72 patients scheduled for elective caesarean section with spinal anesthesia were separated into two groups. In the treatment group, 2 ml of 0.5% bupivacaine plus 25 mg MgSO4 (0.5 ml) were injected intrathecally, and in the control group 2 ml of 0.5% bupivacaine plus 0.5 ml normal saline were injected intrathecally. Core temperature was measured before and after drug injection at predetermined intervals. Sedation was graded using the Ramsay sedation scale. Results: No significant intergroup differences in appearance of shivering were seen immediately or at 5, 30, 40, 50, 60, and 90 min after block administration. However, at 10, 15, and 20 min post block, there was a significant difference in shivering. The group administered MgSO4 showed lower shivering grades compared with the control group. Core temperature was significantly reduced in the MgSO4 group compared to the normal saline group 30 min after blocking. Conclusions: Intrathecal injection of MgSO4 improved perioperative shivering in female patients undergoing elective caesarean section.

A unique “fishtail-like” four-way shape memory effect of compositionally graded NiTi

Meng, Qinglin,Wu, Zhigang,Bakhtiari, Reza,Shariat, Bashir S.,Yang, Hong,Liu, Yinong,Nam, Tae-hyun Elsevier 2017 Scripta materialia Vol.127 No.-

<P><B>Abstract</B></P> <P>This paper reports a complex four-way shape memory effect of a compositionally graded NiTi thin plate. The composition gradient is created by surface diffusion of Ni into the plate. After a 15% tensile deformation pre-treatment, the compositionally graded plate exhibits a complex four-way shape memory effect in bending mode, by which the metal exhibits a back-and-forth shape change upon a complete thermal cycle. This is analogous to a “fishtail-like” motion, resulting from the sequential transformation through the thickness of the plate as dictated by Ni content gradient. Such “four-way” shape memory effect has not been achieved in NiTi alloys before.</P> <P><B>Graphical abstract</B></P> <P>Complex “4-way” shape memory behaviour of a compositionally graded NiTi thin strip after 15% of tensile deformation. In this figure, the sample bends towards one direction (increase of curvature) initially and then bends backwards (decrease of curvature) upon one cooling (the blue curve). The same process repeats also during heating, thus exhibiting shape change in four directions within one complete thermal cycle.</P> <P>[DISPLAY OMISSION]</P>

Effect of Substrate's Heat Treatment on Microstructure and Mechanical Properties TLP Bonding of Dissimilar X-45/FSX-414 Cobalt Based Superalloys

Mojtaba Naalchian,Masoud Kasiri‑Asgarani,Morteza Shamanian,Reza Bakhtiari,Hamid Reza Bakhsheshi‑Rad 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.11

In this study, a dissimilar joint of cobalt based superalloys X-45 and FSX-414 has been created under the standard heattreatment conditions with the nickel-based BNi-9 interlayer with the thickness of 50 μm by the transient liquid phase bondingprocess. Solution heat treatment (1150 °C/4 h) was used for bonding and the aging heat treatment (980 °C/4 h) for thehomogenization of the bond. Optical metallography, Field Emission Scanning Electron Microscope with Energy DispersiveX-ray Spectroscopy, Differential scanning calorimetry, micro-hardness test and shear strength test were used for the characterizationof microstructural and mechanical evolution in base metals and bonds. The solution heat treatment leads to thedissolution of a part of the M23C6and M6Ccarbides in the substrate of superalloys, which due to the aging heat treatmentsecondary and fine carbides M23C6precipitate in the substrate and help strengthen the superalloys. The diffusion of theboron from the molten interlayer to the base metals resulted in the complete isothermal solidification and a nickel-basedsingle-phase solid solution has been developed. Cobalt-chromium-tungsten-molybdenum-based carboborides precipitationwith high hardness in the vicinity of the isothermal solidification zone and in base metals results in the non-homogeneityof microhardness profile along the bonding area. Homogenization heat treatment did not have an effect on the omission ofthese precipitations, but by more uniform redistribution of the alloying elements strengthen solid solution that could increaseshear strength from 655 to 688 MPa, which is somewhat equivalent to the shear strength of the 45-X alloy and also 93% ofthe shear strength of the FSX-414 alloy.

Functionally graded shape memory alloys: Design, fabrication and experimental evaluation

Shariat, Bashir S.,Meng, Qinglin,Mahmud, Abdus S.,Wu, Zhigang,Bakhtiari, Reza,Zhang, Junsong,Motazedian, Fakhrodin,Yang, Hong,Rio, Gerard,Nam, Tae-hyun,Liu, Yinong Elsevier 2017 Materials & Design Vol.124 No.-

<P><B>Abstract</B></P> <P>Functionally graded shape memory alloys have the advantage of combining the functionalities of the shape memory effect and those of functionally graded structures. By proper design, they can exhibit new and complex deformation behaviour that is unmatched in uniform shape memory alloys. One obvious advantage of functionally graded shape memory alloys is their widened transformation stress and temperature windows that provide improved controllability in actuating applications. This paper reports on the concept, fabrication, experimentation and thermomechanical behaviour of several designs of functionally graded NiTi alloys, including compositionally graded, microstructurally graded and geometrically graded NiTi alloys, and the various techniques that may be used to create these functionally graded materials. It is found that the property gradients created along the loading direction or perpendicular to the loading direction produce distinct thermomechanical behaviours. The property gradient along the loading direction provides stress gradient over stress-induced transformation, which can be adjusted by the property gradient profile. The property gradient through the thickness direction of plate specimens and perpendicular to the loading direction provides four-way shape memory behaviour during stress-free thermal cycling after tensile deformation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Functionally graded shape memory alloys provide widened transformation stress and temperature windows in actuation application. </LI> <LI> The property gradient was achieved in three ways: microstructural gradient, compositional gradient and geometrical gradient. </LI> <LI> Property gradients created along the loading direction or perpendicular to that direction produce distinct thermomechanical behaviours. </LI> <LI> A variety of techniques has been proposed for fabricating functionally graded shape memory alloy structures. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>