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.
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.
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.
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.
In this work, a robust brazed joint of carbon fibre-reinforced carbon-based (c/c) composite and Tc4 alloy was produced by utilising a slice of c/c as an interlayer. The c/c slice interlayer caused microstructural and ...
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In this work, a robust brazed joint of carbon fibre-reinforced carbon-based (c/c) composite and Tc4 alloy was produced by utilising a slice of c/c as an interlayer. The c/c slice interlayer caused microstructural and mechanical property enhancement. During brazing, massive in situ formed carbon fibres broke away from the c/c slice bundles and were distributed in a three-dimensional interlocked network. These unique fibres consumed excessive Ti to inhibit the formation of excess brittle Ti-cu compounds in the brazing seam. This reduced the coefficient of thermal expansion effectively, consequently relieving the high residual stress in the joint interface. The average shear strength of the joint brazed with the c/c slice interlayer reached 1.65 times higher than the directly brazed one.
Sol-gel is a promising technology to prepare the c/c-Zrc-Siccomposites. However, carbon fiber erosion caused by carbothermal reduction severely degrades properties of the composites. At present study, the addition or...
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Sol-gel is a promising technology to prepare the c/c-Zrc-Siccomposites. However, carbon fiber erosion caused by carbothermal reduction severely degrades properties of the composites. At present study, the addition order of carbon source during sol-gel process was optimized to improve the microstructure, mechanical property and ablation resistance of the composites. Results show that adding phenolic resin before gelation combined with deposited pyrocarbon interlayer around the carbon fibers can greatly alleviate the degradation of the c/ c-Zrc-Siccomposites by reducing the carbon fiber erosion. The composites thus prepared delivered the flexural strength, mass and linear ablation rates are 162.58 MPa, 0.147 mg/(cm2.s) and 0.0098 mm/s, respectively, which are 449% higher, 9.26% lower and 38.36% lower than those of the counterpart that added phenolic resin after gelation. The excellent performance is attributed to little erosion of the carbon fibers and the dense matrix of Zrc-Sicceramics obtained from adding carbon source before gelation during the sol-gel process.
carbon fiber reinforced carbon matrix (c/c) composites have been used in aerospace applications due to their excellent performance. Exploring their failure mechanisms is a subject of extensive research. Nowadays, to o...
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carbon fiber reinforced carbon matrix (c/c) composites have been used in aerospace applications due to their excellent performance. Exploring their failure mechanisms is a subject of extensive research. Nowadays, to obtain information about changes in the failure processes, a technology known as in situ X-ray computed to-mography is used. In this paper, tensile loads were applied to 3D fine-woven punctured and needle-punched c/ccomposites perpendicular to the punctured and needle-punched directions. In situ X-ray computed tomography was employed to observe damage development, and digital volume correlation was used to assess the laboratory X-ray computed tomographs to measure local strains. Assimilation of pores is observed in c/ccomposites, with cracks evolving from original micro-pores. While fine-woven punctured c/ccomposites present an elegant linear failure, needle-punched c/ccomposites present a traditional non-linear failure. This difference is due to the different structures of the preforms. Furthermore, the c/ccomposites are weak at the sites where they are punctured or needle-punched.
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