Mechanical and Structural Stability of Perovskites Membranes in Reducing Environments

2002 ◽  
Vol 752 ◽  
Author(s):  
Nagendra Nagabhushana ◽  
William F. Haslebacher ◽  
Venkat K. Venkataraman ◽  
Sukumar Bandopadhyay
Keyword(s):  
Mechanical Stability ◽  
High Strength ◽  
Air Separation ◽  
Membrane Reactors ◽  
Structure Property ◽  
A Site ◽  
Long Term Behavior ◽  
Catalytic Membrane Reactors ◽  
Perovskite Type

ABSTRACTMixed ionic electronic conducting perovskite type oxides are promising materials for potential use in various applications such as in fuel cells and membranes for air separation. An important issue in the development of the perovskites is the structural, chemical and mechanical stability of these materials at high temperatures and reducing environments (oxygen partial pressure from 0.21 to 10−17 atm) encountered in membrane reactors. SrFeO3 oxides doped with La on the A-site and Cr on the B-site showed high strength at room temperature in air. The strength degrades rapidly with an increase in temperature in air as compared to in N2 and CO2/CO environment. Fracture in the material is characterized by non-equilibrium segregation of elements within the grains. The observations provide valuable structure-property correlation as applicable to the long-term behavior of the material in advanced catalytic membrane reactors.

Tailoring of La0.8Ce0.1Ni0.4Ti0.6O3-δ catalyst interlayer via in-situ exsolution for catalytic membrane reactor

2021 ◽  
Author(s):  
Ping Luo ◽  
Zhi Xu ◽  
Qiankun Zheng ◽  
Jinkun Tan ◽  
Zhicheng Zhang ◽  
...  
Keyword(s):  
Membrane Reactor ◽  
Membrane Reactors ◽  
Catalytic Membrane ◽  
Membrane Material ◽  
Catalytic Membrane Reactor ◽  
Permeable Membrane ◽  
A Site ◽  
Catalytic Membrane Reactors ◽  
Perovskite Type

The application of catalytic membrane reactors (CMRs) based on perovskite-type oxygen-permeable membrane has been greatly limited by the instability of membrane material. In this study, A-site deficient perovskite La0.8Ce0.1Ni0.4Ti0.6O3-δ (LCNT)...

Fe/Mn-based Perovskite-Type Oxides with Excellent Oxygen Permeability and Reduction Tolerance

2004 ◽  
Vol 835 ◽  
Author(s):  
Yasutake Teraoka ◽  
Hironobu Shimokawa ◽  
Hajime Kusaba ◽  
Kazunari Sasaki
Keyword(s):  
Partial Oxidation ◽  
Synthesis Gas ◽  
Oxygen Permeability ◽  
Membrane Reactors ◽  
Permeation Flux ◽  
Low Oxygen ◽  
Reducing Atmosphere ◽  
A Site ◽  
Perovskite Type ◽  
Perovskite Type Structure

ABSTRACTA family of Co-free, Fe/Mn-based perovskite-type oxides, (Sr, A')(Fe, Mn)O3-δ (A'=La, Ba, Ca), was synthesized, and their oxygen permeability and phase stability in reducing atmosphere were investigated. The substitution of Mn at B site caused the decrease in oxygen permeability. As for the effect of A-site substitution, prominent promotion was observed by the substitution of Ba for 30% of Sr, and Ba0.3Sr0.7FeO3-δ was found to be one of most excellent oxygen permeable materials with the permeation flux of 3.0 cm3(STP) cm−2 min−1 at 900 °C. Reduction tolerance was evaluated by TG measurements in a 5%H2/N2 stream up to 1000 °C. After the TG measurements, crystal structures of La-Sr-Co-Fe-O and Sr-Fe-(Mn)-O perovskites were decomposed or transformed into low oxygen permeable phases, but the perovskite-type structure of Ba-Sr-Fe-(Mn)-O survived. The Fe/Mn-based perovskites with high oxygen permeability and exceeding reduction tolerance could be used as stable membrane materials for membrane reactors catalyzing NO-CH4 reaction and the partial oxidation of CH4 into synthesis gas.

scholarly journals Theoretical Investigation of Nonlinear Time-Dependent Behavior of Two-Way High-Strength Concrete Walls

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Yue Huang ◽  
Rui Rao ◽  
Yonghui Huang ◽  
Zilin Zhong
Keyword(s):  
Geometric Nonlinearity ◽  
High Strength Concrete ◽  
High Strength ◽  
Time Dependent ◽  
Fourier Series Expansion ◽  
Time Step ◽  
Strength Concrete ◽  
Dependent Behavior ◽  
Long Term Behavior

High-strength concrete (HSC) walls have been increasingly used in the past decades. However, the time-dependent behavior of HSC wall panels in two-way action was not investigated, and the time effect of creep is not included in the design codes in most countries. For this purpose, the nonlinear long-term behavior of two-way HSC wall is investigated in this paper. A theoretical model is developed using time-stepping analysis considering geometric nonlinearity and creep of concrete. A rheological material model that is based on the generalized Maxwell chain is adopted to model the concrete creep. Von Karman plate theory is used to derive the incremental governing equations. The equations are solved numerically at each time step based on a Fourier series expansion of the deformations and loads and numerical multiple shooting method. It shows that the model can effectively predict the time-dependent behavior of two-way HSC panels, where the out-of-plane deflection and internal bending moments increase with time due to the combined effects of creep and geometric nonlinearity, which may ultimately lead to creep buckling failures. A parametric study shows that the long-term behavior of the panel is very sensitive to the in-plane load level and eccentricity, slenderness ratio, aspect ratio, and edge support conditions.

LONG TERM BEHAVIOR OF CONCRETE MEMBER STRENGTHENED WITH INTERNAL PRESTRESSING SYSTEM

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Isamu Yoshitake ◽  
Tatsuhiko Mimoto ◽  
Takuya Sakaki ◽  
Jun Mizushima
Keyword(s):  
High Strength ◽  
Concrete Member ◽  
Loading Test ◽  
Concrete Members ◽  
Prestressing Force ◽  
Pull Out ◽  
Long Term Behavior ◽  
Strengthening Method ◽  
Prestressing Tendon

To maintain and retrofit appropriately concrete structures, various strengthening materials and methods have been developed and applied. One of the effective and reliable strengthening method for concrete is an application of the prestressing system. The present study focuses on a strengthening system using an internal anchorage and a prestressing tendon. The strengthening system is acceptable even in relatively narrow workspaces, and also applicable for joints between existing and additional concrete members. In our previous investigations, a static push-out and pull-out tests were performed to examine the load-bearing capacity of the prestressing tendon embedded in the wedge anchor. The test confirmed that the prestressing tendon can be anchored firmly in an internal wedge hole filled with high-strength mortar. Long-term behavior of the strengthened member should be examined to confirm the applicability of the system. The load and deformation of a concrete member subjected to sustained force by the prestressing bar were measured for 1 year. This paper reports the long-term loading test, and discusses the time-dependent properties of the strengthened concrete member. The test result confirms that the loss of prestressing force is negligible for actual applications.

scholarly journals Long-term Test Arrangement for Externally Strengthened Reinforced Concrete Elements

10.14311/452 ◽  
2003 ◽  
Vol 43 (4) ◽  
Author(s):  
T. Vaňura ◽  
P. Štěpánek ◽  
I. Švaříčková ◽  
J. Adámek
Keyword(s):  
Epoxy Resin ◽  
Epoxy Resins ◽  
Glass Fibers ◽  
High Strength ◽  
Space Saving ◽  
External Strengthening ◽  
Long Term Behavior ◽  
Concrete Elements ◽  
Special Space

Methods for external strengthening of concrete use elements of very high tensional strength glued on to its tensioned surface. These elements may be of metal, carbon fibers (CFRP), glass fibers or others, usually having very good mechanical properties. However, these high-strength elements are normally attached to concrete by epoxy resins. Epoxy resins have a low Young`s modulus and therefore a higher rate of creep may have an influence on the long-term behavior of such external strengthening. In order to verify this idea experimentally a special space-saving arrangement of tests is described in this paper. Panels act as loaded beams but simultaneously as a load for the other panels in a stand. The different load magnitude acting on a different layer of panels should make it possible to study the long-term influence of the degree of shear force on the glue creep. Certainly, the glue creep may be dependent on the type of epoxy resin; therefore several epoxy resin types are included in the tests.

Subcritical Crack Growth and Long-Term Strength in Rock and High-Strength and Ultra Low-Permeability Concrete

2009 ◽  
Vol 58 (6) ◽  
pp. 525-532 ◽  
Author(s):  
Yoshitaka NARA ◽  
Masafumi TAKADA ◽  
Daisuke MORI ◽  
Hitoshi OWADA ◽  
Tetsuro YONEDA ◽  
...  
Keyword(s):  
Crack Growth ◽  
Subcritical Crack Growth ◽  
High Strength ◽  
Low Permeability ◽  
Term Strength

KUBOTA KNC-03

Alloy Digest ◽  
2010 ◽  
Vol 59 (1) ◽  
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
High Strength ◽  
Temperature Performance ◽  
Resistance To Oxidation

Abstract Kubota KNC-03 is a grade with a combination of high strength and excellent resistance to oxidation. These properties make this alloy suitable for long-term service at temperature up to 1250 deg C (2282 deg F). This datasheet provides information on physical properties, hardness, elasticity, tensile properties, and compressive strength as well as creep. It also includes information on high temperature performance as well as casting and joining. Filing Code: Ni-676. Producer or source: Kubota Metal Corporation, Fahramet Division. See also Alloy Digest Ni-662, April 2008.

ATI 6-2-4-2

Alloy Digest ◽  
2020 ◽  
Vol 69 (8) ◽  
Keyword(s):  
Tensile Strength ◽  
Titanium Alloy ◽  
High Temperature ◽  
Creep Strength ◽  
High Strength ◽  
Heat Treating ◽  
Good Combination ◽  
Long Term Stability ◽  
Temperature Performance

Abstract ATI 6-2-4-2 is a near-alpha, high strength, titanium alloy that exhibits a good combination of tensile strength, creep strength, toughness, and long-term stability at temperatures up to 425 °C (800 °F). Silicon up to 0.1% frequently is added to improve the creep resistance of the alloy. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as creep. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: Ti-169. Producer or Source: ATI.

scholarly journals Structure-Properties Correlation of Cross-Linked Penicillin G Acylase Crystals

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 451
Author(s):  
Marta Kubiak ◽  
Janine Mayer ◽  
Ingo Kampen ◽  
Carsten Schilde ◽  
Rebekka Biedendieck
Keyword(s):  
Mechanical Stability ◽  
Structural Characteristics ◽  
Penicillin G ◽  
Bacillus Species ◽  
Diffusion Limitations ◽  
Small Water ◽  
Long Term Stability ◽  
Atomic Force ◽  
First Time

In biocatalytic processes, the use of free enzymes is often limited due to the lack of long-term stability and reusability. To counteract this, enzymes can be crystallized and then immobilized, generating cross-linked enzyme crystals (CLECs). As mechanical stability and activity of CLECs are crucial, different penicillin G acylases (PGAs) from Gram-positive organisms have proven to be promising candidates for industrial production of new semisynthetic antibiotics, which can be crystallized and cross-linked to characterize the resulting CLECs regarding their mechanical and catalytic properties. The greatest hardness and Young’s modulus determined by indentation with an atomic force microscope were observed for CLECs of Bacillus species FJAT-PGA CLECs (26 MPa/1450 MPa), followed by BmPGA (Priestia megaterium PGA, 23 MPa/1170 MPa) and BtPGA CLECs (Bacillus thermotolerans PGA, 11 MPa/614 MPa). In addition, FJAT- and BtPGA CLECs showed up to 20-fold higher volumetric activities compared to BmPGA CLECs. Correlation to structural characteristics indicated that a high solvent content and low number of cross-linking residues might lead to reduced stability. Furthermore, activity seems to be restricted by small water channels due to severe diffusion limitations. To the best of our knowledge, we show for the first time in this study that the entire process chain for the characterization of diverse industrially relevant enzymes can be performed at the microliter scale to discover the most important relationships and limitations.

scholarly journals Partial Decellularization for Segmental Tracheal Scaffold Tissue Engineering: A Preliminary Study in Rabbits

Biomolecules ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 866
Author(s):  
Luong Huu Dang ◽  
Yuan Tseng ◽  
How Tseng ◽  
Shih-Han Hung
Keyword(s):  
Mechanical Stability ◽  
Vital Staining ◽  
Potential Method ◽  
Term Survival ◽  
Long Term Survival ◽  
Cartilage Cells ◽  
Preliminary Study ◽  
Epithelial Layers

In this study, we developed a new procedure for the rapid partial decellularization of the harvested trachea. Partial decellularization was performed using a combination of detergent and sonication to completely remove the epithelial layers outside of the cartilage ring. The post-decellularized tracheal segments were assessed with vital staining, which showed that the core cartilage cells remarkably remained intact while the cells outside of the cartilage were no longer viable. The ability of the decellularized tracheal segments to evade immune rejection was evaluated through heterotopic implantation of the segments into the chest muscle of rabbits without any immunosuppressive therapy, which demonstrated no evidence of severe rejection or tissue necrosis under H&E staining, as well as the mechanical stability under stress-pressure testing. Finally, orthotopic transplantation of partially decellularized trachea with no immunosuppression treatment resulted in 2 months of survival in two rabbits and one long-term survival (2 years) in one rabbit. Through evaluations of posttransplantation histology and endoscopy, we confirmed that our partial decellularization method could be a potential method of producing low-immunogenic cartilage scaffolds with viable, functional core cartilage cells that can achieve long-term survival after in vivo transplantation.

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