scholarly journals Study of ALDH from Thermus thermophilus–Expression, Purification and Characterisation of the Non-Substrate Specific, Thermophilic Enzyme Displaying Both Dehydrogenase and Esterase Activity

Cells ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3535
Author(s):  
Kim Shortall ◽  
Edel Durack ◽  
Edmond Magner ◽  
Tewfik Soulimane
Keyword(s):  
Heat Treatment ◽  
Life Form ◽  
Thermus Thermophilus ◽  
Gel Filtration ◽  
Aldehyde Dehydrogenases ◽  
E Coli ◽  
Ability To Act ◽  
High Yields ◽  
Treatment Step ◽  
Heat Treatment Step

Aldehyde dehydrogenases (ALDH), found in all kingdoms of life, form a superfamily of enzymes that primarily catalyse the oxidation of aldehydes to form carboxylic acid products, while utilising the cofactor NAD(P)+. Some superfamily members can also act as esterases using p-nitrophenyl esters as substrates. The ALDHTt from Thermus thermophilus was recombinantly expressed in E. coli and purified to obtain high yields (approximately 15–20 mg/L) and purity utilising an efficient heat treatment step coupled with IMAC and gel filtration chromatography. The use of the heat treatment step proved critical, in its absence decreased yield of 40% was observed. Characterisation of the thermophilic ALDHTt led to optimum enzymatic working conditions of 50 °C, and a pH of 8. ALDHTt possesses dual enzymatic activity, with the ability to act as a dehydrogenase and an esterase. ALDHTt possesses broad substrate specificity, displaying activity for a range of aldehydes, most notably hexanal and the synthetic dialdehyde, terephthalaldehyde. Interestingly, para-substituted benzaldehydes could be processed efficiently, but ortho-substitution resulted in no catalytic activity. Similarly, ALDHTt displayed activity for two different esterase substrates, p-nitrophenyl acetate and p-nitrophenyl butyrate, but with activities of 22.9 and 8.9%, respectively, compared to the activity towards hexanal.

Heat Treatment of Friction Surfaced Steel-Aluminum Couple

2015 ◽  
Vol 830-831 ◽  
pp. 135-138 ◽  
Author(s):  
K. Udaya Bhat ◽  
Nithin ◽  
Suma Bhat ◽  
Sudeendran
Keyword(s):  
Heat Treatment ◽  
Solid State ◽  
Mild Steel ◽  
Steel Surface ◽  
Aluminum Layer ◽  
Friction Surfacing ◽  
State Process ◽  
Aluminide Layer ◽  
Treatment Step ◽  
Heat Treatment Step

Friction surfacing is a solid state process and it is amenable for deposition of aluminum on steel. In this investigation, the mild steel surface was coated with a layer of aluminum using friction surfacing route. The aluminum thickness was in the range of 40-50 μm. It was followed by a heat treatment step to convert aluminum layer in to an aluminide layer. Heat treatment was done in open atmosphere at 700 °C for 2 hours. Microstuctural analysis showed that the aluminide layer is mainly made of Fe2Al5 and Fe4Al13, FeAl and Fe3Al are minor in fraction. Formation of Fe2Al5 is discussed. The aluminide layer also has some amount of porosities.

scholarly journals Effect of heat treatment residual stress on stress behavior of constant stress beam

2017 ◽  
Vol 5 (1) ◽  
pp. 137-143 ◽  
Author(s):  
Si Young Kwak ◽  
Ho Young Hwang
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
External Load ◽  
Treatment Process ◽  
Constant Stress ◽  
Design Stage ◽  
Treatment Processes ◽  
Stress Behavior ◽  
Treatment Step ◽  
Heat Treatment Step

Abstract Although most casting and heat treatment processes generate significantly high residual stress in the products, this factor is generally not taken into account in the design stage of the product. In this study, experimental study and numerical analysis were conducted on a constant stress beam to examine effects of the residual stress generated during the heat treatment process on yielding behavior of the product in use. A constant stress beam of SUS 304 was designed in order to test the stress behavior related to residual stress. The residual stresses generated during quenching heat treatment of the beam were measured in advance by ESPI (Electronic Speckle-Pattern Interferometry) equipment, and then the external stresses generated while applying a simple external load on the beam were measured. Also, the residual stress distribution generated during the heat treatment process was computed using a numerical analysis program designed for analyzing heat treatment processes. Then, the stress distribution by a simple external load to the beam was combined with the calculated residual stress results of the previous heat treatment step. Finally, the results were compared with experimental ones. Simulation results were in good agreement with the experimental results. Consistency between experimental results and computational results prove that residual stress has significant effects on the stress behavior of mechanical parts. Therefore, the residual stress generated in the previous heat treatment step of casting must be taken into account in the stage of mechanical product design. Highlights The bigger compressive residual stress occurs, the closer surface. When the residual stress is close to plastic deformation, the stress by external load did not significantly change. The residual stress generated during the manufacturing process should be considered in the design stage.

Reduction in transmission of hepatitis C after the introduction of a heat-treatment step in the production of C1-inhibitor concentrate

Transfusion ◽  
1995 ◽  
Vol 35 (3) ◽  
pp. 209-212 ◽  
Author(s):  
M. Cicardi ◽  
P. M. Mannucci ◽  
R. Castelli ◽  
M. G. Rumi ◽  
A. Agostoni
Keyword(s):  
Heat Treatment ◽  
Hepatitis C ◽  
C1 Inhibitor ◽  
Treatment Step ◽  
Heat Treatment Step

Microstructure and Tensile Ductility of a Ti-43Al-4Nb-1Mo-0.1B Alloy

2008 ◽  
Vol 1128 ◽  
Author(s):  
Laura M. Droessler ◽  
Thomas Schmoelzer ◽  
Wilfried Wallgram ◽  
Limei Cha ◽  
Gopal Das ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermodynamic Equilibrium ◽  
Room Temperature ◽  
Volume Fraction ◽  
Tensile Ductility ◽  
Heat Treatments ◽  
Air Cooling ◽  
B2 Phase ◽  
Treatment Step ◽  
Heat Treatment Step

AbstractThe microstructural development of a forged Ti-43Al-4Nb-1Mo-0.1B (in at%) alloy during two-step heat-treatments was investigated and its impact on the tensile ductility at room temperature was analyzed. The investigated material, a so-called TNM™ gamma alloy, solidifies via the β-route, exhibits an adjustable β/B2-phase volume fraction and can be forged under near conventional conditions. Post-forging heat-treatments can be applied to achieve moderate to near zero volume fractions of β/B2-phase allowing for a controlled adjustment of the mechanical properties. The first step of the heat-treatment minimizes the β/B2-phase and adjusts the size of the α-grains, which are a precursor to the lamellar γ/α2-colonies. However, due to air cooling after the first annealing step, the resulting microstructure is far from thermodynamic equilibrium. Therefore, a second heat-treatment step is conducted below the eutectoid temperature which brings the microstructural constituents closer to thermodynamic equilibrium. It was found that temperature and duration of the second heat-treatment step critically affect the solid-state phase transformations and, thus, control the plastic fracture strain at room temperature. Scanning and transmission electron microscopy studies as well as hardness tests have been conducted to characterize the multi-phase microstructure and to study its correlation to the observed room temperature ductility.

scholarly journals High Pressure Heat Treatment of AM Parts—Combining HIP and Heat Treatment

2019 ◽  
Author(s):  
Magnus Ahlfors
Keyword(s):  
Heat Treatment ◽  
Hot Isostatic Pressing ◽  
Vacuum Furnace ◽  
Creep Ductility ◽  
Post Process ◽  
Treatment Step ◽  
Hip Process ◽  
Heat Treatment Step ◽  
Defect Elimination ◽  
Metal Additive

Abstract Hot Isostatic Pressing (HIP) has been used for several decades within different industries for a wide variety of applications [1]. During the recent years HIP has become an important post process for metal additive manufacturing (AM) to secure material performance and quality. The HIP process uses a high isostatic pressure and elevated temperature to densify additively manufactured material by eliminating internal defects. The elimination of defects results in improved material properties such as fatigue, creep, ductility and fracture toughness [2-8]. HIP have historically been used only for densification and defect elimination and any modification and optimization of a material’s microstructure is usually performed after the HIP process in a separate heat treatment step in separate equipment e.g. a vacuum furnace. The main reason that these processes have been performed separately is that the achievable cooling rates in HIP systems have traditionally been relatively low, lower than what many materials require for heat treatment to for example create martensite or a super saturated condition.

scholarly journals Thermostable manganese (II) dependent α-glycosidase from Pseudothermotoga thermarum

BioResources ◽  
2019 ◽  
Vol 14 (3) ◽  
pp. 7266-7274
Author(s):  
Hao Shi ◽  
Yue Liu ◽  
Jiannan Guo ◽  
Yang Cao ◽  
Xianyan Zhu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Gel Filtration ◽  
Recombinant Enzyme ◽  
Relative Molecular Mass ◽  
Optimal Temperature ◽  
Good Thermal Stability ◽  
E Coli ◽  
Purification System ◽  
Optimal Ph

Alpha-glycosidase degrades polysaccharides and oligosaccharides and participates in the synthesis of oligosaccharides through a process called transglycosylation. In this study, an α-glycosidase gene pthgly from Pseudothermotoga thermarum was cloned using pET-20b as a vector and was expressed in E. coli BL21(DE3). After heat treatment and affinity chromatography, the resulting recombinant enzyme was purified. The purity of the enzyme reached a single band at a molecular weight of approximately 55 kDa. The properties of the recombinant enzyme were determined. The optimal temperature of α-glycosidase (Pthgly) was 90 °C and the optimal pH was 7.5. In addition, Pthgly exhibited good thermal stability at 70 °C and 75 °C. The relative molecular mass of the recombinant enzyme was 116 kDa, as determined by a protein purification system with a gel filtration column. Furthermore, α-glycosidase possessed Michaelis-Menten kinetics with a Km and Vmax of 0.29 ± 0.01 mmol l-1 and 22.12 ± 1.31 μmol min-1 mg-1, respectively.

Initial Stages of Lamellae Formation in High Nb Containing γ-TiAl Based Alloys

2008 ◽  
Vol 1128 ◽  
Author(s):  
Limei Cha ◽  
Christina Scheu ◽  
Gerhard Dehm ◽  
Ronald Schnitzer ◽  
Helmut Clemens
Keyword(s):  
Heat Treatment ◽  
Phase Field ◽  
Volume Fraction ◽  
Transmission Electron ◽  
Initial Stage ◽  
The Matrix ◽  
Small Volume Fraction ◽  
Step Heat Treatment ◽  
Treatment Step ◽  
Heat Treatment Step

AbstractIn this study a two-step heat treatment was applied to high Nb containing γ-TiAl based alloys in order to investigate the initial stage of the lamellae formation in ordered α2-grains as well as in massively transformed γm-grains. The first heat treatment step, conducted in the single α-phase field followed by oil quenching, leads to a microstructure consisting of supersaturated α2-grains and a small volume fraction of γm-grains. The second step of the heat treatment was performed below the eutectoid temperature, i.e. within the (α2+γ)-phase field region and was again followed by oil quenching. There, the formation of ultra-fine γ-lamellae takes place in the α2-grains and (some) fine α2-lamellae are formed in the γm-grains. In both cases the lamellae show a Blackburn orientation relationship with the matrix grain. It was found that the precipitation of γ-laths in the supersaturated α2-grains is faster than the formation of α2-laths in γm-grains. The characteristics of the initial stage of formation were investigated by transmission electron microscopy.

scholarly journals Microstructural Investigations of Low Temperature Joining of Q&P Steels Using Ag Nanoparticles in Combination with Sn and SnAg as Activating Material

2019 ◽  
Vol 9 (3) ◽  
pp. 539 ◽  
Author(s):  
Susann Hausner ◽  
Martin Wagner ◽  
Guntram Wagner
Keyword(s):  
Heat Treatment ◽  
Ag Nanoparticles ◽  
Low Temperatures ◽  
Retained Austenite ◽  
Steel Substrate ◽  
High Strength ◽  
The One ◽  
Treatment Step ◽  
Heat Treatment Step ◽  
Strength And Ductility

Quenching and partitioning (Q&P) steels show a good balance between strength and ductility due to a special heat treatment that allows to adjust a microstructure of martensite with a fraction of stabilized retained austenite. The final heat treatment step is performed at low temperatures. Therefore, joining of Q&P steels is a big challenge. On the one hand, a low joining temperature is necessary in order not to influence the adjusted microstructure; on the other hand, high joint strengths are required. In this study, joining of Q&P steels with Ag nanoparticles is investigated. Due to the nano-effect, high-strength and temperature-resistant joints can be produced at low temperatures with nanoparticles, which meets the contradictory requirements for joining of Q&P steels. In addition to the Ag nanoparticles, activating materials (SnAg and Sn) are used at the interface to achieve an improved bonding to the steel substrate. The results show that the activating materials play an important role in the successful formation of joints. Only with the activating materials, can joints be produced. Due to the low joining temperature (max. 237 °C), the microstructure of the Q&P steel is hardly influenced.

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