In this work, the effects of c, N, and Al on the microstructures and creep properties of Fe-cr-Al-Nb-W ferritic alloys were investigated through scanning electron microscopy, x-ray diffractometry, as well as uniaxial ...
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In this work, the effects of c, N, and Al on the microstructures and creep properties of Fe-cr-Al-Nb-W ferritic alloys were investigated through scanning electron microscopy, x-ray diffractometry, as well as uniaxial creep testing and hardness testing. The results demonstrated that the matrix of the Fe-cr-Al-Nb-W heat-resistant steel was ferrite, while the precipitation phases were Laves phases, M23c6 carbides and MX nitride phases. M23c6 and MX precipitated at grain interior, Laves phases precipitated at grain interior, grain boundary and around MX phases. c, N and Al affected microstructure and creep of heat-resistant steel. As the Al content increased or as N content decreased along with the c increase, the average diameter of the Laves phases, along with M23c6 and MX phase grain interior decrease. Moreover, the unit density increased and the phase spacing decreased, which led to the minimum creep rate decrease and creep rupture time increase. compared to M23c6, Laves and MX phases mainly affected the alloy creep strength. The decrease of Laves phase continuity coefficient (ratio of Laves phase particle spacing and size) on the grain boundary was conducive to the plasticity improvement of heat-resistant steel.
Recently, fabricating one-dimensional (1D) nanomaterials on c/ccomposite has been recognized effective to improve the thermal shock resistance of the coated composites. However, the remaining metal catalyst in cVD pr...
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Recently, fabricating one-dimensional (1D) nanomaterials on c/ccomposite has been recognized effective to improve the thermal shock resistance of the coated composites. However, the remaining metal catalyst in cVD process and the week bond of 1D nanomaterials with substrate limit the strengthening effect. Herein, laser chemical vapor deposition (LcVD) was proposed for fabricating porous Sic nanostructured coating on c/ccomposite without metal catalyst. The laser heating resulted in a temperature gradient between the top and bottom of the coating, providing an external driving force for the vertical growth of whiskers with side-branches, forming a porous network nanostructure. The porous nanostructure was beneficial to reduce cTE and effectively relieve thermal stress. After 10 times of thermal shock test from RT to 1723 K, the porous Sic nanostructured coating remained intact. This work provides a novel methodology to produce functional coating on c/ccomposite with outstanding thermal shock resistance.
In this paper, the torsion and flexural-torsional coupled mechanical properties of different c/Sic torque tubes were investigated for the testing condition at room and elevated temperatures. Effects of fiber types, fi...
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In this paper, the torsion and flexural-torsional coupled mechanical properties of different c/Sic torque tubes were investigated for the testing condition at room and elevated temperatures. Effects of fiber types, fiber preforms, and small hole during fabrication process on torsion mechanical properties were investigated. Flexural -torsional coupled mechanical tests for c/Sic torque tubes with different external diameter and wall thickness were conducted at room and elevated temperatures. The torsion and flexural moments and corresponding shear and flexural strength were obtained. The fracture surface and cracks propagation path were observed and analyzed. The torque and shear strength in T300TM-3k torque tube were much higher than those of T300TM-1k torque tube. Among 3D needled (3DN), 2D plain-woven [0 degrees /90 degrees] and [+/- 45 degrees] c/Sic torque tubes, the density, torque, and shear strength of 3DN-c/Sic torque tube were the highest. For the c/Sic torque tubes with small hole, the small hole not only increased the densification and uniformity (axial and radial) of the torque tube, but also has the potential to make the damage cracks more zigzag, which improved the fracture toughness of the torque tubes.
This paper reports the temperature dependence of d.c. and a.c. conductivity in the glassy alloys of Se70Te30 and Se70Te28M2 (M = cd, Sb, Zn). The role of the cd, Sb, Zn elements as foreign atoms has been examined on t...
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This paper reports the temperature dependence of d.c. and a.c. conductivity in the glassy alloys of Se70Te30 and Se70Te28M2 (M = cd, Sb, Zn). The role of the cd, Sb, Zn elements as foreign atoms has been examined on the d.c./a.c. conduction and photoconduction in binary Se70Te30 glass. These multi-component chalcogenide glasses have been prepared by conventional, cost-effective and well-known melt-quench technique. Thermally activated a.c. conduction shows the presence of the compensation effect that is confirmed by the Meyer-Neldel relation between the associated activation energy and the pre-factor of a.c. conductivity. The metal-induced effects of cd, Sb, Zn on the photosensitivity of parent glass are also discussed.
Several leaves and shoot spot symptoms were observed on tomato (Lycopersicon esculentum Mill) plants at Zubair and Safwan farms in Basrah, Iraq. The symptomatic plant parts were collected from different varieties of t...
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Several leaves and shoot spot symptoms were observed on tomato (Lycopersicon esculentum Mill) plants at Zubair and Safwan farms in Basrah, Iraq. The symptomatic plant parts were collected from different varieties of tomato. The fungal pathogens were first isolated on PDA medium followed by a diagnosis procedure of the relevant fungi conducting phenotypiccharacterization and microscopic featuring. A molecular identification was applied by polymerase chain reaction technology using internal transcribed spacer sequences. All along an investigation on cladosporium species, three species including c. cladosporioides, c. oxysporum, and c. uredinicola were identified and recorded as new potential pathogen for the first time in Iraq causing leaf spot and lesion of tomato plant. Pathogenicity examination of each isolated pathogens was performed against of tomato plant. The importance of the current research is to investigate and identify the fungal pathogens of tomato plants to find the best protocols to restrict their growth and damage.
The reductions of cytochrome c by a series of derivatives of Fe(EDTA)2- complex have been studied by a stopped-flow technique. The reactions of cytochrome c with Fe(EDTA)2-, Fe (cDTA)2- and Fe(IDA)22- present typical ...
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The reductions of cytochrome c by a series of derivatives of Fe(EDTA)2- complex have been studied by a stopped-flow technique. The reactions of cytochrome c with Fe(EDTA)2-, Fe (cDTA)2- and Fe(IDA)22- present typical outer sphere mechanism, meanwhile the cytochrome c(III) and Fe(NTA)- system shows abnormal kinetic behavior, including the rate saturation, big negative entropy and lower overall charge and binding site charge calculated from the dependence of electron transfer rate on ionic strength. On the basis of these observations a semi-inner-sphere mechanism is proposed to illustrate the kinetics.
For conversion of renewable biomass, boron (B)-doped porous c/SiOx composites (B@c/SiOx) were prepared from rice husks and H3BO3 via a simple annealing process. The introduction of B induces the extrinsic defects and ...
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For conversion of renewable biomass, boron (B)-doped porous c/SiOx composites (B@c/SiOx) were prepared from rice husks and H3BO3 via a simple annealing process. The introduction of B induces the extrinsic defects and additional active sites, tunes the chemistry of carbon skeleton, and improves electrochemical performance of composites. The B-doped c skeleton substantially relieves volume change of SiOx and enhances the electronicconductivity of composites. The unique porous structure, large specific surface area, and B-doping endow B@c/SiOx with the high cycling capacity, excellent rate property, and exceptional cycling stability. Moreover, B doping can significantly decrease the Li+ migration barrier in c matrix of c/SiOx. When applied as Li-ion batteries anode, the optimized electrode harvests a cycling capacity of 1040 mAh g(-1) under 0.1 A g(-1) after 100 cycles with an elevated initial coulombic efficiency (cE) of 70.2%, and long cycle life up to 1000 cycles with a capacity of 610 mAh g(-1) under 1.0 A g(-1). This research sheds light on the thoughts of biomass-derived materials for sustainable energy storage devices.
Tools for computer-aided teaching and learning provide multiple benefits from the point of view of teaching because it allows emphasizing or illustrating certain issues that are sometimes difficult to emphasize withou...
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Tools for computer-aided teaching and learning provide multiple benefits from the point of view of teaching because it allows emphasizing or illustrating certain issues that are sometimes difficult to emphasize without such type of support. This is exactly the case for the tools to detect if there is any type of problem in a concurrent-c program. These tools provide interfaces that can complement the information given by a compiler with additional information about different types of race conditions and memory leaks that appear in the code. This article aims to address how to integrate a core validation tools for concurrent-c as a web application, allowing you to be accessible through the Internet. This tool has been evaluated in an existing programming course, which has shown to be able to provide additional information useful to the learner and the teacher. There have also been a number of performance measures to establish operational limits designed tool within a course that teaches concurrent-c programming.
We have investigated scintillation and thermally-stimulated luminescence (TSL) dosimetric properties of Al2O3 transparent ceramics doped with different concentrations of c ions (0.001, 0.01 and 0.1%). The samples were...
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We have investigated scintillation and thermally-stimulated luminescence (TSL) dosimetric properties of Al2O3 transparent ceramics doped with different concentrations of c ions (0.001, 0.01 and 0.1%). The samples were synthesized by the Spark Plasma Sintering (SPS) technique. All the samples showed scintillation with emission peaks at 310, 410 and 693 nm under X-ray irradiation. Based on the scintillation decay times measured, the origins of emissions at 310, 410 and 693 nm were attributed to F+ centers, F centers and cr3+ impurity ions, respectively. The samples show notable TSL with a glow curve consisting of peaks at 30, 100, 165, 230, 330 and 405 degrees c with much higher intensities than those of undoped Al2O3 transparent ceramics. A TSL response was confirmed to be linear to the irradiation dose over a range from 0.1 to 1000 mGy.
The turnover of native and applied c and N in undisturbed soil samples of different texture but similar mineralogical composition, origin and cropping history was evaluated at -10 kPa water potential. cores of structu...
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The turnover of native and applied c and N in undisturbed soil samples of different texture but similar mineralogical composition, origin and cropping history was evaluated at -10 kPa water potential. cores of structurally intact soil with 108, 224 and 337 g clay kg(-1). were horizontially sliced and N-15-labelled sheep faeces was placed between the two halves of the intact core. The cores together with unamended treatments were incubated in the dark at 20degreesc and the evolution Of cO2-c determined continuously for 177 d. Inorganic and microbial biomass N and N-15 were determined periodically. Net nitrification was less in soil amended with faeces compared with unamended soil. When adjusted for the NO3-N present in soil before faeces was applied, net nitrification became negative indicating that NO3-N had been immobilized or denitrified. The soil most rich in clay nitrified least N and N-15. The amounts of N retained in the microbial biomass in unamended soils increased with clay content. A maximum of 13% of the faeces N-15 was recovered in the microbial biomass in the amended Soils. cO2-c evolution increased with clay content in amended and unamended soils. cO2-c evolution from the most sandy soil was reduced due to a low content of potentially mineralizable native soil c whereas the rate constant of c mineralization rate peaked in this soil. When the pool of potentially mineralizable native soil c was assumed proportional to volumetric water content, the three soils contained similar proportions of potentially mineralizable native soil c but the rate constant of c mineralization remained highest in the soil with least clay. Thus although a similar availability of water in the three soils was ensured by their identical matric potential, the actual volume of water seemed to determine the proportion of total c that was potentially mineralizable. The proportion of mineralizable c in the faeces was simiiar in the three soils (70% of total c), again with a higher rat
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