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https://www.readbyqxmd.com/read/29772842/fe-based-nano-materials-in-catalysis
#1
REVIEW
Stavros Alexandros Theofanidis, Vladimir V Galvita, Christos Konstantopoulos, Hilde Poelman, Guy B Marin
The role of iron in view of its further utilization in chemical processes is presented, based on current knowledge of its properties. The addition of iron to a catalyst provides redox functionality, enhancing its resistance to carbon deposition. FeOx species can be formed in the presence of an oxidizing agent, such as CO₂, H₂O or O₂, during reaction, which can further react via a redox mechanism with the carbon deposits. This can be exploited in the synthesis of active and stable catalysts for several processes, such as syngas and chemicals production, catalytic oxidation in exhaust converters, etc...
May 17, 2018: Materials
https://www.readbyqxmd.com/read/29772835/one-dimensional-and-two-dimensional-analytical-solutions-for-functionally-graded-beams-with-different-moduli-in-tension-and-compression
#2
Xue Li, Jun-Yi Sun, Jiao Dong, Xiao-Ting He
The material considered in this study not only has a functionally graded characteristic but also exhibits different tensile and compressive moduli of elasticity. One-dimensional and two-dimensional mechanical models for a functionally graded beam with a bimodular effect were established first. By taking the grade function as an exponential expression, the analytical solutions of a bimodular functionally graded beam under pure bending and lateral-force bending were obtained. The regression from a two-dimensional solution to a one-dimensional solution is verified...
May 17, 2018: Materials
https://www.readbyqxmd.com/read/29772834/mechanism-of-reduced-sintering-temperature-of-al%C3%A2-o%C3%A2-%C3%A2-zro%C3%A2-nanocomposites-obtained-by-microwave-hydrothermal-synthesis
#3
Iwona Koltsov, Julita Smalc-Koziorowska, Marta Prześniak-Welenc, Maria Małysa, Giora Kimmel, Jessica McGlynn, Alexey Ganin, Swietlana Stelmakh
A novel method to obtain Al₂O₃⁻ZrO₂ nanocomposites is presented. It consists of the co-precipitation step of boehmite (AlO(OH)) and ZrO₂, followed by microwave hydrothermal treatment at 270 °C and 60 MPa, and by calcination at 600 °C. Using this method, we obtained two nanocomposites: Al₂O₃⁻20 wt % ZrO₂ and Al₂O₃⁻40 wt % ZrO₂. Nanocomposites were characterized by Fourier transformed infrared spectroscopy, Raman spectroscopy, X-ray diffraction, and transmission electron microscopy...
May 17, 2018: Materials
https://www.readbyqxmd.com/read/29772832/characterization-of-luminescent-materials-with-151-eu-m%C3%A3-ssbauer-spectroscopy
#4
REVIEW
Franziska Steudel, Jacqueline A Johnson, Charles E Johnson, Stefan Schweizer
The application of Mössbauer spectroscopy to luminescent materials is described. Many solids doped with europium are luminescent, i.e., when irradiated with light they emit light of a longer wavelength. These materials therefore have practical applications in tuning the light output of devices like light emitting diodes. The optical properties are very different for the two possible valence states Eu 2 + and Eu 3 + , the former producing ultraviolet/visible light that shifts from violet to red depending on the host and the latter red light, so it is important to have a knowledge of their behavior in a sample environment...
May 17, 2018: Materials
https://www.readbyqxmd.com/read/29772804/plasmonic-nanowires-for-wide-wavelength-range-molecular-sensing
#5
Giovanni Marinaro, Gobind Das, Andrea Giugni, Marco Allione, Bruno Torre, Patrizio Candeloro, Jurgen Kosel, Enzo Di Fabrizio
In this paper, we propose the use of a standing nanowires array, constituted by plasmonic active gold wires grown on iron disks, and partially immersed in a supporting alumina matrix, for surface-enhanced Raman spectroscopy applications. The galvanic process was used to fabricate nanowires in pores of anodized alumina template, making this device cost-effective. This fabrication method allows for the selection of size, diameter, and spatial arrangement of nanowires. The proposed device, thanks to a detailed design analysis, demonstrates a broadband plasmonic enhancement effect useful for many standard excitation wavelengths in the visible and NIR...
May 17, 2018: Materials
https://www.readbyqxmd.com/read/29772802/effect-of-ultrasonic-vibration-on-mechanical-properties-of-3d-printing-non-crystalline-and-semi-crystalline-polymers
#6
Guiwei Li, Ji Zhao, Wenzheng Wu, Jili Jiang, Bofan Wang, Hao Jiang, Jerry Ying Hsi Fuh
Fused deposition modeling 3D printing has become the most widely used additive manufacturing technology because of its low manufacturing cost and simple manufacturing process. However, the mechanical properties of the 3D printing parts are not satisfactory. Certain pressure and ultrasonic vibration were applied to 3D printed samples to study the effect on the mechanical properties of 3D printed non-crystalline and semi-crystalline polymers. The tensile strength of the semi-crystalline polymer polylactic acid was increased by 22...
May 17, 2018: Materials
https://www.readbyqxmd.com/read/29772790/combined-effects-of-set-retarders-and-polymer-powder-on-the-properties-of-calcium-sulfoaluminate-blended-cement-systems
#7
Seongwoo Gwon, Seung Yup Jang, Myoungsu Shin
This study investigates the effects of set retarders on the properties of polymer-modified calcium sulfoaluminate (CSA) and Portland cement blend systems at early and long-term ages. The fast setting of the cement blend systems is typically adjusted by using retarders to ensure an adequate workability. However, how the addition of retarders influences the age-dependent characteristics of the cement blend systems was rarely investigated. This study particularly examines the effects of retarders on the microstructure and strength development of polymer-modified CSA and Portland cement blend pastes and mortars from 2 h to 90 days...
May 17, 2018: Materials
https://www.readbyqxmd.com/read/29772767/electrical-performance-and-reliability-improvement-of-amorphous-indium-gallium-zinc-oxide-thin-film-transistors-with-hfo%C3%A2-gate-dielectrics-by-cf%C3%A2-plasma-treatment
#8
Ching-Lin Fan, Fan-Ping Tseng, Chiao-Yuan Tseng
In this work, amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs) with a HfO₂ gate insulator and CF₄ plasma treatment was demonstrated for the first time. Through the plasma treatment, both the electrical performance and reliability of the a-IGZO TFT with HfO₂ gate dielectric were improved. The carrier mobility significantly increased by 80.8%, from 30.2 cm²/V∙s (without treatment) to 54.6 cm²/V∙s (with CF₄ plasma treatment), which is due to the incorporated fluorine not only providing an extra electron to the IGZO, but also passivating the interface trap density...
May 17, 2018: Materials
https://www.readbyqxmd.com/read/29772766/in-situ-synthesis-of-al-based-mmcs-reinforced-with-aln-by-mechanical-alloying-under-nh%C3%A2-gas
#9
E S Caballero, F G Cuevas, F Ternero, R Astacio, J M Montes, J Cintas
Aluminum matrix composites (AMCs) reinforced by aluminum nitride were prepared by mechanical alloying followed by a simple press and sintering method. Milling began under vacuum and after a period of between 1 and 4 h, NH₃ gas flow (1 cm³/s) was incorporated until the total milling time of 5 h was reached. Results show that in addition to the strain hardening taking place during mechanical alloying, NH₃ plays an additional role in powder hardening. Thereby, the properties of the sintered compacts are strongly influenced by the amount of N incorporated into the powders during milling and the subsequent formation of AlN during the consolidation process...
May 17, 2018: Materials
https://www.readbyqxmd.com/read/29772760/a-review-of-carbon-nanomaterials-synthesis-via-the-chemical-vapor-deposition-cvd-method
#10
REVIEW
Yehia M Manawi, Ayman Samara, Tareq Al-Ansari, Muataz A Atieh
Carbon nanomaterials have been extensively used in many applications owing to their unique thermal, electrical and mechanical properties. One of the prime challenges is the production of these nanomaterials on a large scale. This review paper summarizes the synthesis of various carbon nanomaterials via the chemical vapor deposition (CVD) method. These carbon nanomaterials include fullerenes, carbon nanotubes (CNTs), carbon nanofibers (CNFs), graphene, carbide-derived carbon (CDC), carbon nano-onion (CNO) and MXenes...
May 17, 2018: Materials
https://www.readbyqxmd.com/read/29772752/ion-doping-effects-on-the-lattice-distortion-and-interlayer-mismatch-of-aurivillius-type-bismuth-titanate-compounds
#11
Yu Chen, Jiageng Xu, Shaoxiong Xie, Zhi Tan, Rui Nie, Zhongwei Guan, Qingyuan Wang, Jianguo Zhu
Taking Bismuth Titanate (Bi₄Ti₃O12 ) as a Aurivillius-type compound with m = 3 for example, the ion (W6+ /Cr3+ ) doping effect on the lattice distortion and interlayer mismatch of Bi₄Ti₃O12 structure were investigated by stress analysis, based on an elastic model. Since oxygen-octahedron rotates in the ab-plane, and inclines away from the c-axis, a lattice model for describing the status change of oxygen-octahedron was built according to the substituting mechanism of W6+ /Cr3+ for Ti4+ , which was used to investigate the variation of orthorhombic distortion degree ( a/b ) of Bi₄Ti₃O12 with the doping content...
May 17, 2018: Materials
https://www.readbyqxmd.com/read/29772733/effect-of-babassu-natural-filler-on-pbat-phb-biodegradable-blends-an-investigation-of-thermal-mechanical-and-morphological-behavior
#12
Vinicius C Beber, Silvio de Barros, Mariana D Banea, Markus Brede, Laura H de Carvalho, Ron Hoffmann, Anna Raffaela M Costa, Elieber B Bezerra, Ingridy D S Silva, Katharina Haag, Katharina Koschek, Renate M R Wellen
Blending of biodegradable polymers in combination with low-price organic fillers has proven to be a suitable approach to produce cost-effective composites in order to address pollution issues and develop products with superior mechanical properties. In the present research work PBAT/PHB/Babassu composites with 25, 50, and 75% of each polymer and 20% of Babassu were produced by melting extrusion. Their thermal, mechanical, and morphological behavior was investigated by differential scanning calorimetry (DSC), tensile testing, and scanning electron microscopy (SEM)...
May 16, 2018: Materials
https://www.readbyqxmd.com/read/29772729/palladium-iridium-and-rhodium-supported-catalysts-predictive-h%C3%A2-chemisorption-by-statistical-cuboctahedron-clusters-model
#13
Fabien Drault, Clément Comminges, Fabien Can, Laurence Pirault-Roy, Florence Epron, Anthony Le Valant
Chemisorption of hydrogen on metallic particles is often used to estimate the metal dispersion ( D ), the metal particle size ( d ), and the metallic specific surface area ( SM ), currently assuming a stoichiometry of one hydrogen atom H adsorbed per surface metal atom M . This assumption leads to a large error when estimating D , d , and SM , and a rigorous method is needed to tackle this problem. A model describing the statistics of the metal surface atom and site distribution on perfect cuboctahedron clusters, already developed for Pt, is applied to Pd, Ir, and Rh, using the density functional theory (DFT) calculation of the literature to determine the most favorable adsorption sites for each metal...
May 16, 2018: Materials
https://www.readbyqxmd.com/read/29772728/preparation-and-thermal-properties-of-molecular-bridged-expanded-graphite-polyethylene-glycol-composite-phase-change-materials-for-building-energy-conservation
#14
Dong Zhang, Meizhu Chen, Quantao Liu, Jiuming Wan, Jinxuan Hu
Using phase change materials (PCMs) in building envelopes became a reliable method to improve indoor comfort and reduce buildings' energy consumption. This research developed molecular-bridged expanded graphite (EG)/polyethylene glycol (PEG) composite PCMs (m-EPs) to conserve energy in buildings. The m-EPs were prepared through a vacuum absorption technique, and a titanate coupling agent was used to build a molecular bridge between EG and PEG. SEM, mercury intrusion porosimetry (MIP), the leakage test, microcalorimetry, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) were conducted to characterize the morphology, pore structure, absorbability, and modifying effects of the m-EPs...
May 16, 2018: Materials
https://www.readbyqxmd.com/read/29772726/an-alternative-lifetime-model-for-white-light-emitting-diodes-under-thermal%C3%A2-electrical-stresses
#15
Xi Yang, Bo Sun, Zili Wang, Cheng Qian, Yi Ren, Dezhen Yang, Qiang Feng
The lifetime prediction using accelerated degradation test (ADT) method has become a main issue for white light emitting diodes applications. This paper proposes a novel lifetime model for light emitting diodes (LEDs) under thermal and electrical stresses, where the junction temperature and driving current are deemed the input parameters for lifetime prediction. The features of LEDs' lifetime and the law of lumen depreciation under dual stresses are combined to build the lifetime model. The adoption of thermal and electrical stresses overcomes the limitation of single stress, and junction temperature in accelerated degradation test as thermal stress is more reliable than ambient temperature in conventional ADT...
May 16, 2018: Materials
https://www.readbyqxmd.com/read/29772723/evolution-of-grain-interfaces-in-annealed-duplex-stainless-steel-after-parallel-cross-rolling-and-direct-rolling
#16
Ming Wang, Haoqing Li, Yujing Tian, Hong Guo, Xiaoying Fang, Yuebin Guo
Changes in various grain interfaces, including the grain boundary and phase boundary, are a strong indication of microstructural changes, particularly ultra-fined grains achieved by large strain deformation and subsequent annealing. After direct rolling and cross rolling with the same strain of ε = 2, the distributions of the interfaces in annealed UNS S32304 duplex stainless steel were investigated using electron backscatter diffraction (EBSD) in this study. The ferrite experienced continued recovery, and a high density of low-angle grain boundaries (LAGBs) was produced...
May 16, 2018: Materials
https://www.readbyqxmd.com/read/29772721/the-effect-of-rod-shaped-long-period-stacking-ordered-phases-evolution-on-corrosion-behavior-of-mg-95-33-zn%C3%A2-y-2-67-alloy
#17
Jingfeng Wang, Weiyan Jiang, Shengfeng Guo, Yang Li, Yao Ma
The morphology evolution of long-period stacking ordered (LPSO) phases on corrosion behavior of Mg95.33 Zn₂Y2.67 alloy is investigated systematically during as-cast, pre-extrusion heat-treated, as-extruded and post-extrusion heat-treated conditions. The second phases in the as-cast alloy are only LPSO phases with a few Y particles. The pre-extrusion heat treatment changed LPSO phases from blocks into a rudimentary rod shape with lamellar structure, subsequently into fine fragments by extrusion, and then into a regular rod shape with lamellar structure followed by post-extrusion heat treatment...
May 16, 2018: Materials
https://www.readbyqxmd.com/read/29772719/3-bis-pyridin-2-ylmethyl-amino-5-4-carboxyphenyl-bodipy-as-ratiometric-fluorescent-sensor-for-cu-2
#18
Akira Hafuka, Hisashi Satoh, Koji Yamada, Masahiro Takahashi, Satoshi Okabe
We developed an asymmetric fluorescent sensor 1 for Cu2+ , based on 4,4-difluoro-4-bora-3a,4a-diaza- s -indacene (BODIPY), by introducing 4-carboxyphenyl and bis(pyridin-2-ylmethyl)amine groups at the 5- and 3-positions, respectively, of the BODIPY core. We then investigated the photophysical and cation-sensing properties of the sensor. BODIPY 1 showed large absorption and fluorescence spectral shifts on binding to Cu2+ . The fluorescence peak at 580 nm red-shifted to 620 nm. The binding stoichiometry of BODIPY 1 and Cu2+ was 1:3...
May 16, 2018: Materials
https://www.readbyqxmd.com/read/29772711/biomimetic-superhydrophobic-hollowed-out-pyramid-surface-based-on-self-assembly
#19
Weipeng Luo, Bin Yu, Dingbang Xiao, Meng Zhang, Xuezhong Wu, Guoxi Li
In this paper, we present a periodic hollowed-out pyramid microstructure with excellent superhydrophobicity. In our approach, T-topping pillars and capillary-induced self-assembly methods were combined with the photolithography process to fabricate a hollowed-out pyramid structure. First, a wideband ultraviolet source without a filter was used to fabricate the T-topping pillars during the exposure process; then, the evaporation-induced assembly collapsed the pillars and formed the hollowed-out pyramid structure...
May 16, 2018: Materials
https://www.readbyqxmd.com/read/29772708/microstructure-evolution-and-mechanical-behavior-of-2219-aluminum-alloys-additively-fabricated-by-the-cold-metal-transfer-process
#20
Xuewei Fang, Lijuan Zhang, Hui Li, Chaolong Li, Ke Huang, Bingheng Lu
In this research, four different welding arc modes including conventional cold metal transfer (CMT), CMT-Pulse (CMT-P), CMT-Advanced (CMT-ADV), and CMT pulse advanced (CMT-PADV) were used to deposit 2219-Al wire. The effects of different arc modes on porosity, pore size distribution, microstructure evolution, and mechanical properties were thoroughly investigated. The statistical analysis of the porosity and its size distribution indicated that the CMT-PADV process gave the smallest pore area percentage and pore aspect ratio, and had almost no larger pores...
May 16, 2018: Materials
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