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1
Gajdardziska-Josifovska, M., B. G. Frost, E. Völkl y L. F. Allard. "On the Faceting of Polar Ceramic Surfaces: Microscopy and Holography Studies of MGO(111) Surfaces". Proceedings, annual meeting, Electron Microscopy Society of America 54 (11 de agosto de 1996): 366–67. http://dx.doi.org/10.1017/s0424820100164295.
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Polar surfaces are those crystallographic faces of ionically bonded solids which, when bulk terminated, have excess surface charge and a non-zero dipole moment perpendicular to the surface. In the case of crystals with a rock salt structure, {111} faces are the exemplary polar surfaces. It is commonly believed that such polar surfaces facet into neutral crystallographic planes to minimize their surface energy. This assumption is based on the seminal work of Henrich which has shown faceting of the MgO(111) surface into {100} planes giving rise to three sided pyramids that have been observed by scanning electron microscopy. These surfaces had been prepared by mechanical polishing and phosphoric acid etching, followed by Ar+ sputtering and 1400 K annealing in ultra-high vacuum (UHV). More recent reflection electron microscopy studies of MgO(111) surfaces, annealed in the presence of oxygen at higher temperatures, have revealed relatively flat surfaces stabilized by an oxygen rich reconstruction. In this work we employ a combination of optical microscopy, transmission electron microscopy, and electron holography to further study the issue of surface faceting.
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Waseda, Y., S. Suzuki y K. Urbanb. "Novel Morphology of Voids in Single-Quasicrystalline Icosahedral Al70.5Pd21.0Mn8.5". Zeitschrift für Naturforschung A 53, n.º 8 (1 de agosto de 1998): 679–83. http://dx.doi.org/10.1515/zna-1998-0806.
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Abstract This paper deals with the morphology and surface chemistry of faceted voids existing in singlequasicrystalline icosahedral Al70.5Pd21.0Mn8.5. By observation with a scanning electron microscope of surfaces obtained by cleavage of the quasicrystal, the habit planes of the dodecahedral voids were identified. The chemical surface composition of the void surface was determined by Auger electron spectroscopy after cleavage in ultra-high vacuum.
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Kong, Ling Bao, Chi Fai Cheung, Suet To y Wing Bun Lee. "Development of a Dynamic Model for Ultra-Precision Raster Milling". Key Engineering Materials 364-366 (diciembre de 2007): 58–63. http://dx.doi.org/10.4028/www.scientific.net/kem.364-366.58.
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Optical freeform surface requires submicrometer form accuracy and nanometer surface finish. Ultra-precision raster milling is an emerging technology in the fabrication of those surfaces in which the dynamics factors are vital to achieve the surface quality. This paper presents a theoretical dynamics model for ultra-precision raster milling. The cutting force is derived in the depth of cut (DOC) planes in the feed and raster directions. Hence, a 3D cutting force model is established. The cutting force induced deflection between tool and workpiece is determined which can be employed to analyze the influence of the deflection on the surface generation in raster milling. The dynamic model is useful for modeling of surface generation and further control of vibration between the tool and the workpiece.
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Guo, Zhong Ning, Z. G. Yang, Z. G. Hang, Z. Q. Yu, T. M. Yue y Wing Bun Lee. "Analysis of Dynamic Characteristics in Polishing Based on Two-Dimension Vibration of Fluid". Key Engineering Materials 304-305 (febrero de 2006): 295–99. http://dx.doi.org/10.4028/www.scientific.net/kem.304-305.295.
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A novel polishing technique based on the two-dimension vibration of fluid is put forward to obtain ultra-smooth surface without damage. In operation, the polishing pad is replaced by fluid where fine abrasive particles are mixed, and the impact and grinding effect can be produced by means of the vibration of fluid and the relative motion of workpiece. It can achieve the ultra-precise polishing for all kinds of planes and curved surfaces. A finite element method is employed to analyze the dynamic behaviors, including vibration mode and harmonic response under the action of the exciter, and the fluid field based on two-dimension vibration is simulated.
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Sander, Tim, Yi Liu, Tuan Anh Pham, Maximilian Ammon, Mirunalini Devarajulu y Sabine Maier. "Ultra-high vacuum cleaver for the preparation of ionic crystal surfaces". Review of Scientific Instruments 93, n.º 5 (1 de mayo de 2022): 053703. http://dx.doi.org/10.1063/5.0088802.
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Cleaving single crystals in situ under ultra-high vacuum conditions provides a reliable and straightforward approach to prepare clean and atomically well-defined surfaces. Here, we present a versatile sample cleaver to efficiently prepare ionic crystal surfaces under ultra-high vacuum conditions, which is suitable for preparation of softer materials, such as alkali halides, and harder materials, such as metal oxides. One of the advantages of the presented cleaver design is that the cleaving blade and anvil to support the crystal are incorporated into the device. Therefore, no particularly strong mechanical manipulator is needed, and it is compatible with existing vacuum chambers equipped with an xyz-manipulator. We demonstrate atomically flat terraces and the atomic structure of NaCl(001), KBr(001), NiO(001), and MgO(001) cleavage planes prepared in situ under ultra-high vacuum conditions and imaged by low-temperature non-contact atomic force microscopy.
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Touge, Mutsumi, Satoru Anan, Shogo Wada, Akihisa Kubota, Yoshitaka Nakanishi y Junji Watanabe. "Atomic-Scale Planarization of Single Crystal Diamond Substrates by Ultraviolet Rays Assisted Machining". Key Engineering Materials 447-448 (septiembre de 2010): 66–70. http://dx.doi.org/10.4028/www.scientific.net/kem.447-448.66.
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The ultra-precision polishing assisted by the ultraviolet rays irradiation was performed to achieve the atomic-scale planarization of the single crystal diamond substrates. This polishing method is a novel and simple polishing method characterizing by a quartz disk and an ultraviolet irradiation device. The principle three crystal planes of the diamond substrate were polished by this method. The polished surfaces were evaluated by an optical interferometric profilers (Wyko), an atom force microscope (AFM) and LEED (low-energy electron diffraction). The surface roughness of the polished diamond substrates was evaluated as 0.2 ~ 0.4 nmRa in (100), (110) and (111) crystal planes. The LEED (low-energy electron diffraction) patterns indicated the almost perfect crystallographic structure without the residual processed strain beneath the polished surface. In this paper, the optimum polishing condition to achieve the atomic-scale planarization of the diamond substrates has been investigated by the evaluation of LEED patterns, Wyko and AFM images. The mechanismof the ultraviolet rays assisted polishing is discussed in detail.
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Lai, Jin, Dong Li, Yong Ai, Hongkun Liu, Deyang Cai, Kangjun Chen, Yuqiang Xie y Guiwen Wang. "Structural diagenesis in ultra-deep tight sandstones in the Kuqa Depression, Tarim Basin, China". Solid Earth 13, n.º 6 (21 de junio de 2022): 975–1002. http://dx.doi.org/10.5194/se-13-975-2022.
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Abstract. The Lower Cretaceous Bashijiqike Formation of the Kuqa Depression is made up of ultra-deeply buried sandstones in fold-and-thrust belts. Few researches have linked diagenetic processes with structure. To fill this gap, a comprehensive analysis integrating diagenesis with structure pattern, fracture and in situ stress is performed following a structural diagenetic approach. The results show that the pore spaces include residual intergranular pores, intergranular and intragranular dissolution pores, and micro-fractures. The sandstones experienced a high degree of mechanical compaction, but compaction is limited in well-sorted rocks or abundant in rigid quartz grains. The most volumetrically important diagenetic minerals are calcites. The framework grains experienced a varied degree of dissolution, and intergranular and intragranular dissolution pores are formed. Special attention is paid on the dissolution associated with the fracture planes. Large numbers of natural fractures are cemented by carbonate cements, which limit fluid flow. In addition, the presence of fracture enhances dissolution and the fracture planes are enlarged by dissolution. Cementation and dissolution can occur simultaneously in fracture surfaces, and the enlarged fracture surfaces can be cemented by late-stage cements. The in situ stress magnitudes are calculated using well logs. The horizontal stress difference (Δσ) determines the degree of mechanical compaction, and rocks associated with low Δσ experienced a low degree of compaction, and these contain preserved intergranular pores. Natural fractures are mainly related to the low Δσ layers. The presence of intergranular and intragranular dissolution pores is mainly associated with the fractured zones. The high-quality reservoirs with intergranular pores or fractures are related to low Δσ layers. The structural diagenesis researches above help the prediction of reservoir quality in ultra-deep sandstones and reduce the uncertainty in deep natural gas exploration in the Kuqa Depression.
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Guo, Xiao Guang, Chang Heng Zhai, Zi Yuan Liu, Liang Zhang, Zhu Ji Jin y Ren Ke Kang. "Research on Elastic-Plastic Transition and Hardening Effect for Monocrystalline Silicon Surfaces". Advanced Materials Research 1027 (octubre de 2014): 101–6. http://dx.doi.org/10.4028/www.scientific.net/amr.1027.101.
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Based on molecular dynamics method, a nanoindentation simulation of the silicon crystal is built and the load-displacement curve is drawn. According to the load-displacement curve, the elastic-plastic transition of silicon crystal is analyzed. The results show that the critical point in the elastic-plastic transition is between 15 and 20 angstroms. In addition, different crystal planes of silicon crystal are loaded for five cycles respectively; the nanohardness is calculated and the nanohardness curve is obtained. The results show that after the first plastic deformation of the silicon crystal surface is occurred, the surface will have a higher hardness and a higher elasticity. Therefore, in the ultra precision machining, in order to reduce the occurrence of damage, the depth of the processing should be controlled in the range of elasticity. Moreover, the method of small quantities in high frequency can increase mechanical properties on the surface.
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Bertin, M., M. Doronin, X. Michaut, L. Philippe, A. Markovits, J. H. Fillion, F. Pauzat, Y. Ellinger y J. C. Guillemin. "Nitrile versus isonitrile adsorption at interstellar grain surfaces". Astronomy & Astrophysics 608 (diciembre de 2017): A50. http://dx.doi.org/10.1051/0004-6361/201731144.
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Context. Almost 20% of the ~200 different species detected in the interstellar and circumstellar media present a carbon atom linked to nitrogen by a triple bond. Of these 37 molecules, 30 are nitrile R-CN compounds, the remaining 7 belonging to the isonitrile R-NC family. How these species behave in their interactions with the grain surfaces is still an open question. Aims. In a previous work, we have investigated whether the difference between nitrile and isonitrile functional groups may induce differences in the adsorption energies of the related isomers at the surfaces of interstellar grains of various nature and morphologies. This study is a follow up of this work, where we focus on the adsorption on carbonaceous aromatic surfaces. Methods. The question is addressed by means of a concerted experimental and theoretical approach of the adsorption energies of CH3CN and CH3NC on the surface of graphite (with and without surface defects). The experimental determination of the molecule and surface interaction energies is carried out using temperature-programmed desorption in an ultra-high vacuum between 70 and 160 K. Theoretically, the question is addressed using first-principle periodic density functional theory to represent the organised solid support. Results. The adsorption energy of each compound is found to be very sensitive to the structural defects of the aromatic carbonaceous surface: these defects, expected to be present in a large numbers and great diversity on a realistic surface, significantly increase the average adsorption energies to more than 50% as compared to adsorption on perfect graphene planes. The most stable isomer (CH3CN) interacts more efficiently with the carbonaceous solid support than the higher energy isomer (CH3NC), however.
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Kokkalas, S., R. R. Jones, K. J. W. McCaffrey y P. Clegg. "Quantitative fault analysis at Arkitsa, Central Greece, using Terrestrial Laser- Scanning ("LIDAR")". Bulletin of the Geological Society of Greece 40, n.º 4 (1 de enero de 2007): 1959. http://dx.doi.org/10.12681/bgsg.17237.
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We applied terrestrial laser scanning (ground-based LiDAR) in the Arkitsa fault zone, an area of active extension along the North Evia Gulf in Central Greece. The study area includes well exposed fault surfaces with large accumulated slip and this allowed detailed measurements of the geometry of the fault planes to be acquired. Laser-scan data enable ultra high-resolution three-dimensional digital terrain models of the recently exposed active fault to be created, in order to apply quantitative fault and slip-vector analysis. This study demonstrates the way in which the Arkitsa Fault is segmented on a smaller scale. The variation in dip and strike across individual fault panels is quantified, and shows the extent to which the fault panel surfaces are non-planar. Although the dip of the different fault panels varies considerably, the average orientation of the slip-vectors on the panels are approximately coincident. The fault is steeply oblique sinistral-normal, with average displacement vector plunging 55° towards 340°.
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Ren, Jie y Ming Lv. "Monocrystalline Nickel Nanogrinding Subsurface Deformation-Layer Depth Study Based on Orthogonal Tests". Coatings 13, n.º 2 (11 de febrero de 2023): 410. http://dx.doi.org/10.3390/coatings13020410.
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Nanogrinding is one of the main technologies for machining complex surface shapes with nanometer-level precision. The subsurface deformation depth, as an important index of machining quality, directly affects the service life and mechanical properties of machined parts. In order to explore the factors that influence subsurface deformation depth, this work investigated the effects of three factors, namely, grinding speed, grinding depth and crystal orientation, along different crystal planes at the depth of the subsurface deformation layer in a monocrystalline nickel nanofabrication process. By combining molecular dynamics simulation and orthogonal tests, the results showed that, among the three aforementioned factors, the influence of crystal orientation at the depth of the subsurface deformation layer was the greatest, followed by that of grinding depth, while the influence of grinding speed was the weakest. Through the orthogonal tests, the factors affecting the significance of subsurface deformation depth were analyzed, and the results were found to be more meaningful compared with those of current single-factor studies. Meanwhile, in-depth exploration of the nanogrinding mechanism can provide the necessary theoretical basis for the development of nanomachining technology, which is of great significance for the improvement of ultra-precision cutting technology.
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Zhao, Zhong-Chao, Jing Ning, Jie Su, Qing-Wei Jiang, Geng Liu, Ding-Hui Liu, Qi Gao y Ao Wang. "Microstructure characterization and mechanical behaviour of laser additive manufactured ultrahigh-strength M54 steel". Materials Research Express 9, n.º 3 (1 de marzo de 2022): 036506. http://dx.doi.org/10.1088/2053-1591/ac5955.
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Abstract Ultra high-strength M54 steel blocks were fabricated by laser metal deposition. The microstructure and mechanical behavior of the material were investigated systematically. The microstructure of the as-deposited M54 steel is anisotropic; the cross-section (XOY plane) has a cellular structure, whereas the longitudinal section (XOZ and YOZ planes) shows a mixture of alternating cellular and columnar forms. Compositional segregation is present at the cell walls (interdendritic regions) in the as-deposited state, resulting in retained austenite at the cell walls. The cross-sectional XOY plane contains 10.08% austenite, whereas the XOZ and YOZ planes contain 24.59% and 22.4% austenite, respectively. The retained austenite at the cell wall (interdendritic region) has low thermal and mechanical stability and disappears after the cryogenic treatment or is transformed into martensite during a tensile test. The as-deposited samples show anisotropic mechanical properties. The transverse samples exhibit stronger transformation-induced plasticity (TRIP) and work hardenability with a lower yield strength of 662 MPa and higher ultimate strength of 1982 MPa, corresponding to a higher amount of retained austenite in this direction. The longitudinal ultimate strength and yield strength are 1832 MPa and 997 MPa, respectively. The ductility and toughness are also largely anisotropic, and their reduction in the transverse direction is only 1/3 of that in the longitudinal direction. The Vickers hardness of the microstructure increases slightly from the bottom to the middle and upper part of the sample due to less thermal cycling in the upper part.
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Chen, Chien-Hung, Yi-Fang Lin y Hua-Ming Chen. "Research on U-shaped tuning stub RFID tag on different objects". International Journal of Microwave and Wireless Technologies 7, n.º 6 (27 de agosto de 2014): 629–36. http://dx.doi.org/10.1017/s1759078714001135.
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A new ultra-high frequency radio frequency identification (RFID) tag antenna, which is comprised a U-shaped tuning stub and a dipole radiator for different permittivity surfaces is investigated, fabricated, and measured. For a conjugate match to the NXP G2XM chip impedance of 29–j137 at 915 MHz, a dipole tag antenna with U-shaped stubconnected to dipole arms was designed. Simple size adjustments of the U-shaped tuning stub and dipole radiator of the antenna allow for easy control of the antenna resistance and inductive reactance, from which the chip impedance requirement may be readily satisfied. The read range of the prototype antenna attached on a different permittivity surfaces (εr= 1–4) can reach more than 4.5 m, which has been tested for an RFID reader with 4.0 W of effective isotropic radiated power. The antenna structure consists of two dipole load bars and two loop electrically connected. The design offers more choice of freedom to tune the input impedance of the proposed antenna. Measurement data are presented which are in good agreement with simulation results. The design is suitable for mounting on all kinds of objects. The fabricated tag sensitivity of −3 dBm, read range of 7 m on the x–z and y–z planes, and the measured orientation radiation patterns were obtained in the desired frequency band.
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Et al., Hamza. "Promoting Solar Cell Efficiencies via Employing Sliver- Carbon- Pomegranate Peel Nano System". Baghdad Science Journal 16, n.º 2 (2 de junio de 2019): 0370. http://dx.doi.org/10.21123/bsj.16.2.0370.
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In this work, a functional nanocomposite consisting of multi walled carbon nanotubes combined with nanoparticles of silver and Pomegranate peel extract (MWCNTs- SNPs -NPGPE) was successfully synthesized using ultra sonic technique. The nanocomposite has been characterized using Transmission electron microscope (TEM), XRD, Energy dispersive X-ray spectroscopy (EDS) UV-Vis and FTIR. The obtained results reveal that the MWCNTs-SNPs-NPGPE nanocomposite exhibits form of nanotubes with rough surfaces and containing black spots, which are the silver nanoparticles. The dimensions of this tube are 161 nm in length and 60 nm in width with nanoparticles of silver not exceeding 20 nm. The XRD pattern of the prepared MWCNTs-SNPs-NPGPE nanocomposite showed four main peaks corresponding to the carbon nanotubes and planes of face centered cubic silver nanoparticles. The IR spectra referring to the(O-H) group stretching vibrations in carboxylic acid groups might come from NPGPE, and the stretching vibration of aliphatic C-H in carbon nanotubes. The carbon nanotube was used in solar cells (CNSCs) fabricated with and/or without fluorine-doped tin oxide (FTO) on the glass substrate with poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methylester (PCBM) blends (P3HT: PCBM). The FTO-(MWCNTs-SNPs-NPGPE / P3HT: PCBM/CNT/FTO-glass revealed more efficient CNSCs.
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Et al., Hamza. "Promoting Solar Cell Efficiencies via Employing Sliver- Carbon- Pomegranate Peel Nano System". Baghdad Science Journal 16, n.º 2 (2 de junio de 2019): 0370. http://dx.doi.org/10.21123/bsj.2019.16.2.0370.
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In this work, a functional nanocomposite consisting of multi walled carbon nanotubes combined with nanoparticles of silver and Pomegranate peel extract (MWCNTs- SNPs -NPGPE) was successfully synthesized using ultra sonic technique. The nanocomposite has been characterized using Transmission electron microscope (TEM), XRD, Energy dispersive X-ray spectroscopy (EDS) UV-Vis and FTIR. The obtained results reveal that the MWCNTs-SNPs-NPGPE nanocomposite exhibits form of nanotubes with rough surfaces and containing black spots, which are the silver nanoparticles. The dimensions of this tube are 161 nm in length and 60 nm in width with nanoparticles of silver not exceeding 20 nm. The XRD pattern of the prepared MWCNTs-SNPs-NPGPE nanocomposite showed four main peaks corresponding to the carbon nanotubes and planes of face centered cubic silver nanoparticles. The IR spectra referring to the(O-H) group stretching vibrations in carboxylic acid groups might come from NPGPE, and the stretching vibration of aliphatic C-H in carbon nanotubes. The carbon nanotube was used in solar cells (CNSCs) fabricated with and/or without fluorine-doped tin oxide (FTO) on the glass substrate with poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methylester (PCBM) blends (P3HT: PCBM). The FTO-(MWCNTs-SNPs-NPGPE / P3HT: PCBM/CNT/FTO-glass revealed more efficient CNSCs.
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Al Hussan, S. M. A., N. A. Bakr, A. N. Abd y M. A. Khalaf. "Fabrication of FTO/Li2O/ZnO/p-PSi/Al solar cell by chemical precipitation method". Journal of Ovonic Research 17, n.º 4 (julio de 2021): 395–403. http://dx.doi.org/10.15251/jor.2021.174.395.
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In this paper, electrochemical etching of the p-type silicon wafer is used to prepare p-type porous silicon with a current density of 10 mA.cm-2 for 10 minutes. Zinc oxide and lithium oxide nanoparticles are prepared separately by chemical precipitation method and simple precipitation method respectively and deposited on glass substrates by drop-casting method. Moreover, the structural and optical properties of the films were analyzed by using XRD and UV-Vis. The XRD results showed that the ZnO and Li2O films are polycrystalline with hexagonal wurtzite structure and cubic structure, and preferred orientation along (101) and (003) planes, respectively. Using Scherrer's formula, the crystallite size was measured and it was found that ZnO and Li2O thin films have a crystallite size of 22.04 and 45.6 nm respectively. The atomic force microscope image and the distribution chart of the grains of the ZnO and Li2O films displayed the grain sizes of~ 58.45 and 83.19 nm. The absorption coefficient spectrum of films were recorded by Ultra Violet–Visible spectrophotometer. The energy band gaps of the films calculated by Tauc’s formula were ~ 4.18 and 5.5 eV. The results demonstrated that the conversion efficiency for Al/Li2O/ZnO/p-PSi/Al, Al/Li2O/ZnO/FTO and FTO/Li2O/ZnO/p-PSi/Al tandem (porous silicon/FTO) solar cells were 0.313%, 0.764% and 24.6%.
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Song, Linsen, Juncheng Song, Junye Li, Tiancheng Wang y Zhenguo Zhao. "Study on the Mechanical Properties of Monocrystalline Germanium Crystal Planes Based on Molecular Dynamics". Micromachines 13, n.º 3 (15 de marzo de 2022): 441. http://dx.doi.org/10.3390/mi13030441.
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Nanoindentation and atomistic molecular dynamics simulations of the loading surface of monocrystalline germanium were used to investigate the evolution of the key structure, the force model, the temperature, the potential, and the deformable layer thickness. The mechanical characteristics of typical crystal planes (001), (110), and (111) of the crystal system were compared under load. It was observed that the hardness and stiffness of the (110) plane were greatest among the three crystal planes, whereas the hardness and stiffness of the (111) plane were lowest. Moreover, the deformation layers at the ends of both planes were basically flat. The processing efficiency of the (111) surface was higher; thus, the (111) surface was considered the best loading surface. It was concluded that the subsurface defects of the monocrystalline germanium (111) plane were smaller and the work efficiency was higher during the processing of monocrystalline germanium, making it ideal for monocrystalline germanium ultra-precision processing.
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Kano, Seisuke y Atsushi Korenaga. "Mechanical Behavior of Single Crystal Copper for Different Shearing Directions". Advanced Materials Research 565 (septiembre de 2012): 490–95. http://dx.doi.org/10.4028/www.scientific.net/amr.565.490.
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The mechanical behavior of the surface of metals is strongly affected by surface fracture occurring in the process of mechanical shearing, especially in shaper-type cutting performed for the application of ultra-fine optical manufacturing and several types of nanotechnology. This discussion aims to elucidate the tribological behavior of pure Cu. In ultra-precise cutting, the physics of crystallographic interfaces is extremely important for controlling surface fracture behavior. In this study, surface fracture behavior was evaluated using single crystal copper cut in two different directions (along the (100) and (111) planes). For V-shaped groove cutting, the flat copper surface was cut with a diamond-tip cutting tool (with a V angle of 90°, a rake angle of 0°, and an escape angle of 7°) at a machining speed of 4-4000 mm/min and a cutting depth of 0.2-10 m. The machined surface was observed with a laser scanning microscope and compared with two groove shapes, in which the cutting grooves in the two cutting directions were found to be different. This result was considered to depend on whether the cutting tool moved along the slip planes {111}, which are oriented in the direction. In the case of shallow cutting (under 1 m), the springback behavior became apparent for cutting in the slip plane direction, where the mechanism of this behavior would be associated with the interface between slip-plane fractures created by the cutting tool.
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McCabe, Matthew F., Matthew Rodell, Douglas E. Alsdorf, Diego G. Miralles, Remko Uijlenhoet, Wolfgang Wagner, Arko Lucieer et al. "The future of Earth observation in hydrology". Hydrology and Earth System Sciences 21, n.º 7 (28 de julio de 2017): 3879–914. http://dx.doi.org/10.5194/hess-21-3879-2017.
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Abstract. In just the past 5 years, the field of Earth observation has progressed beyond the offerings of conventional space-agency-based platforms to include a plethora of sensing opportunities afforded by CubeSats, unmanned aerial vehicles (UAVs), and smartphone technologies that are being embraced by both for-profit companies and individual researchers. Over the previous decades, space agency efforts have brought forth well-known and immensely useful satellites such as the Landsat series and the Gravity Research and Climate Experiment (GRACE) system, with costs typically of the order of 1 billion dollars per satellite and with concept-to-launch timelines of the order of 2 decades (for new missions). More recently, the proliferation of smartphones has helped to miniaturize sensors and energy requirements, facilitating advances in the use of CubeSats that can be launched by the dozens, while providing ultra-high (3–5 m) resolution sensing of the Earth on a daily basis. Start-up companies that did not exist a decade ago now operate more satellites in orbit than any space agency, and at costs that are a mere fraction of traditional satellite missions. With these advances come new space-borne measurements, such as real-time high-definition video for tracking air pollution, storm-cell development, flood propagation, precipitation monitoring, or even for constructing digital surfaces using structure-from-motion techniques. Closer to the surface, measurements from small unmanned drones and tethered balloons have mapped snow depths, floods, and estimated evaporation at sub-metre resolutions, pushing back on spatio-temporal constraints and delivering new process insights. At ground level, precipitation has been measured using signal attenuation between antennae mounted on cell phone towers, while the proliferation of mobile devices has enabled citizen scientists to catalogue photos of environmental conditions, estimate daily average temperatures from battery state, and sense other hydrologically important variables such as channel depths using commercially available wireless devices. Global internet access is being pursued via high-altitude balloons, solar planes, and hundreds of planned satellite launches, providing a means to exploit the internet of things as an entirely new measurement domain. Such global access will enable real-time collection of data from billions of smartphones or from remote research platforms. This future will produce petabytes of data that can only be accessed via cloud storage and will require new analytical approaches to interpret. The extent to which today's hydrologic models can usefully ingest such massive data volumes is unclear. Nor is it clear whether this deluge of data will be usefully exploited, either because the measurements are superfluous, inconsistent, not accurate enough, or simply because we lack the capacity to process and analyse them. What is apparent is that the tools and techniques afforded by this array of novel and game-changing sensing platforms present our community with a unique opportunity to develop new insights that advance fundamental aspects of the hydrological sciences. To accomplish this will require more than just an application of the technology: in some cases, it will demand a radical rethink on how we utilize and exploit these new observing systems.
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Zong, Wen Jun, Dan Li, T. Sun, K. Cheng y Ying Chun Liang. "The Factors Influencing on Cutting Edge Radius of Ultra-Precision Diamond Cutting Tools in Mechanical Lapping". Key Engineering Materials 304-305 (febrero de 2006): 345–49. http://dx.doi.org/10.4028/www.scientific.net/kem.304-305.345.
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A brittle-ductile transition lapping mechanism is proposed for the mechanical lapping of ultra-precision diamond cutting tools, and then the critical depths of cut for brittle-ductile transition in different orientations and on different planes are deduced in theory. Combined the critical lapping depth with the contact accuracy between rotating scaife and lapped tool surface, the influences of processing factors on cutting edge radius are studied. Both the theoretical analyses and experimental results indicate that the vibration of lapping machine tool and surface quality of scaife have enormous influences on the sharpened cutting edge. And lapping compression force has an optimal value. Lapping rate should be considered when lapping velocity is selected. But the smaller the lapping velocity is, the littler the cutting edge radius sharpened. Finally, the optimal selections are performed for each influencing factor and a perfect diamond tool is lapped in ductile mode with a cutting edge radius of 30~40nm and a surface roughness Ra of 0.7nm.
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Liu, Shangfeng, Ye Yuan, Shanshan Sheng, Tao Wang, Jin Zhang, Lijie Huang, Xiaohu Zhang et al. "Four-inch high quality crack-free AlN layer grown on a high-temperature annealed AlN template by MOCVD". Journal of Semiconductors 42, n.º 12 (1 de diciembre de 2021): 122804. http://dx.doi.org/10.1088/1674-4926/42/12/122804.
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Abstract In this work, based on physical vapor deposition and high-temperature annealing (HTA), the 4-inch crack-free high-quality AlN template is initialized. Benefiting from the crystal recrystallization during the HTA process, the FWHMs of X-ray rocking curves for (002) and (102) planes are encouragingly decreased to 62 and 282 arcsec, respectively. On such an AlN template, an ultra-thin AlN with a thickness of ~700 nm grown by MOCVD shows good quality, thus avoiding the epitaxial lateral overgrowth (ELOG) process in which 3–4 μm AlN is essential to obtain the flat surface and high crystalline quality. The 4-inch scaled wafer provides an avenue to match UVC-LED with the fabrication process of traditional GaN-based blue LED, therefore significantly improving yields and decreasing cost.
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Koizumi, M. y M. Niino. "Overview of FGM Research in Japan". MRS Bulletin 20, n.º 1 (enero de 1995): 19–21. http://dx.doi.org/10.1557/s0883769400048867.
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Space planes require high-performance heat-resistant materials which can withstand ultrahigh temperatures and extremely large temperature gradients. To meet these needs, functionally gradient materials (FGMs) were proposed about 10 years ago in Japan.Figure 1 shows a conceptual diagram of functionally gradient materials, taking into account the relaxation of thermal stress. For the surface that contacts high-temperature gases at thousands of degrees, ceramics are used to provide adequate heat resistance. For the surface that provides cooling, metallic materials are used to furnish the necessary thermal conductivity and mechanical strength. In addition, the composition of these materials is formulated to provide optimum distribution of composition, structure, and porosity to effectively relax thermal stress.Since fiscal 1987, an R&D project entitled “Research on Fundamental Techniques to Develop Functionally Gradient Materials for Relaxation of Thermal Stress,” which aimed to develop ultra heat-resistant materials, had been carried out with special coordination funds from the Science and Technology Agency. The five-year project had two phases; Phase I was carried out from 1987 to 1989, and Phase II from 1990 to 1991.
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Öberg, Karin I., Ewine F. van Dishoeck y Harold Linnartz. "Photodesorption of ices – Releasing organic precursors into the gas phase". Proceedings of the International Astronomical Union 4, S251 (febrero de 2008): 449–50. http://dx.doi.org/10.1017/s1743921308022151.
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AbstractA long-standing problem in interstellar chemistry is how molecules can be maintained in the gas phase at the extremely low temperatures in space. Photodesorption has been suggested to explain the observed cold gas in cloud cores and disk mid-planes. We are studying the UV photodesorption of ices experimentally under ultra high vacuum and at astrochemically relevant temperatures (15 – 27 K) using a hydrogen discharge lamp (7-10.5 eV). The ice desorption during irradiation is monitored using reflection absorption infrared spectroscopy and the desorbed species using mass spectrometry. We find that both the UV photodesorption rates and mechanisms are highly molecule specific. CO photodesorbs without dissocation from the surface layer of the ice. N2, which lacks dipole allowed electronic transitions in the range of the lamp, does not photodesorb. CO2 desorbs through dissociation and subsequent recombination from the top few layers of the ice. At low temperatures (15 – 18 K) the derived photodesorption rates are ~ 10−3 for CO and CO2 and < 2 × 10−4 for N2 ice per incident photon.
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Huang, Chia-Yen, Kuo-Bin Hong, Zhen-Ting Huang, Wen-Hsuan Hsieh, Wei-Hao Huang y Tien-Chang Lu. "Challenges and Advancement of Blue III-Nitride Vertical-Cavity Surface-Emitting Lasers". Micromachines 12, n.º 6 (9 de junio de 2021): 676. http://dx.doi.org/10.3390/mi12060676.
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Since the first demonstration of (Al, In, Ga)N-based blue vertical-cavity surface-emitting lasers (VCSELs) in 2008, the maximum output power (Pmax) and threshold current density (Jth) has been improved significantly after a decade of technology advancements. This article reviewed the key challenges for the realization of VCSELs with III-nitride materials, such as inherent polarization effects, difficulties in distributed Bragg’s reflectors (DBR) fabrication for a resonant cavity, and the anti-guiding effect due to the deposited dielectrics current aperture. The significant tensile strain between AlN and GaN hampered the intuitive cavity design with two epitaxial DBRs from arsenide-based VCSELs. Therefore, many alternative cavity structures and processing technologies were developed; for example, lattice-matched AlInN/GaN DBR, nano-porous DBR, or double dielectric DBRs via various overgrowth or film transfer processing strategies. The anti-guiding effect was overcome by integrating a fully planar or slightly convex DBR as one of the reflectors. Special designs to limit the emission polarization in a circular aperture were also summarized. Growing VCSELs on low-symmetry non-polar and semipolar planes discriminates the optical gain along different crystal orientations. A deliberately designed high-contrast grating could differentiate the reflectivity between the transverse-electric field and transverse-magnetic field, which restricts the lasing mode to be the one with the higher reflectivity. In the future, the III-nitride based VCSEL shall keep advancing in total power, applicable spectral region, and ultra-low threshold pumping density with the novel device structure design and processing technologies.
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S, Allen Counter, Peter Damberg, Sahar Nikkhou Aski, Kálmán Nagy, Cecilia Engmér Berglin y Göran Laurell. "Experimental Fusion of Contrast Enhanced High-Field Magnetic Resonance Imaging and High-Resolution Micro-Computed Tomography in Imaging the Mouse Inner Ear". Open Neuroimaging Journal 9, n.º 1 (31 de julio de 2015): 7–12. http://dx.doi.org/10.2174/1874440001509010007.
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Objective: Imaging cochlear, vestibular, and 8th cranial nerve abnormalities remains a challenge. In this study, the membranous and osseous labyrinths of the wild type mouse inner ear were examined using volumetric data from ultra high-field magnetic resonance imaging (MRI) with gadolinium contrast at 9.4 Tesla and high-resolution micro-computed tomography (µCT) to visualize the scalae and vestibular apparatus, and to establish imaging protocols and parameters for comparative analysis of the normal and mutant mouse inner ear. Methods: For in vivo MRI acquisition, animals were placed in a Milleped coil situated in the isocenter of a horizontal 9.4 T Varian magnet. For µCT examination, cone beam scans were performed ex vivo following MRI using the µCT component of a nanoScan PET/CT in vivo scanner. Results: The fusion of Gd enhanced high field MRI and high-resolution µCT scans revealed the dynamic membranous labyrinth of the perilymphatic fluid filled scala tympani and scala vestibule of the cochlea, and semicircular canals of the vestibular apparatus, within the µCT visualized contours of the contiguous osseous labyrinth. The ex vivo µCT segmentation revealed the surface contours and structural morphology of each cochlea turn and the semicircular canals in 3 planes. Conclusions: The fusion of ultra high-field MRI and high-resolution µCT imaging techniques were complementary, and provided high-resolution dynamic and static visualization of the complex morphological features of the normal mouse inner ear structures, which may offer a valuable approach for the investigation of cochlear and vestibular abnormalities that are associated with birth defects related to genetic inner ear disorders in humans.
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Sharma, Harsh, Ajay Kumar, Sravendra Rana y Liberata Guadagno. "An Overview on Carbon Fiber-Reinforced Epoxy Composites: Effect of Graphene Oxide Incorporation on Composites Performance". Polymers 14, n.º 8 (11 de abril de 2022): 1548. http://dx.doi.org/10.3390/polym14081548.
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Carbon fiber-reinforced polymer (CFRP) composites are used in a variety of applications such as aircraft, automobiles, body armors, and the sports sector owing to their ultra-strong and lightweight characteristics. However, the incorporation of an untreated pristine carbon fiber surface leads to a weak interfacial interaction with the polymeric matrix, thus triggering catastrophic failure of the composite material. Graphene oxide, a 2D-macromolecule consisting of several polar functional groups such as hydroxyl, carboxyl, and carbonyl on the basal planes and edges, tends to increase the surface area and has thus been applied between the fiber and matrix, helping to improve CFRP properties. Herein, we condense different routes of functionalization of GO nanosheets and their incorporation onto a fiber surface or in a carbon fiber-reinforced epoxy matrix, helping to improve the interfacial adhesion between the fiber and matrix, and thus allowing effective stress transfer and energy absorption. The improvement of the interfacial adhesion between the fiber and carbon fiber-reinforced epoxy matrix is due to the peculiar structure of GO nanoparticles composed of polar groups, especially on the edges of the nanosheets, able to provide strong interaction with the hosting cured epoxy matrix, and the “core” part similar to the structure of CFs, and hence able to establish strong π-π interactions with the reinforcing CFs. The article also covers the effect of functionalized graphene oxide incorporation on the mechanical, thermal, electrical, and viscoelastic properties of composite materials reinforced with carbon fibers.
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Abdank-Kozubski, Rafal, Andrzej Biborski, Mirosław Kozłowski, Christine Goyhenex, Veronique Pierron-Bohnes, Mebarek Alouani, Marcus Rennhofer y Savko Malinov. "Atomic-Migration-Controlled Processes in Intermetallics". Defect and Diffusion Forum 277 (abril de 2008): 113–18. http://dx.doi.org/10.4028/www.scientific.net/ddf.277.113.
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Chemical ordering kinetics in L10- and B2-ordered AB binary intermetallics was simulated by means of Monte Carlo (MC) technique implemented with vacancy mechanism of atomic migration. While vacancy concentration is usually much lower than the antisite defect concentration in L10-ordered systems, triple defects are generated in particular B2–ordered systems. The latter definitely affects the chemical ordering process and requires that full thermal vacancy thermodynamics is involved in B2-ordering simulations. The study on L10-ordered binaries was dedicated to FePt thin layers considered as a material for ultra-high-density magnetic storage media. Metastability of the L10 c-variant with monoatomic planes parallel to the layer surface and off-plane easy magnetization was revealed. Thermal vacancy formation in B2-ordered binaries was modelled by implementing a mean-field Hamiltonian with a specific formalism of phase equilibria in a latticegas composed of atoms and vacancies. It was demonstrated that for particular pair-interaction energetics, equilibrium concentrations of vacancies and antisites result mutually proportional in well-defined temperature ranges. The MC simulations of B2-ordering kinetics involved the modelled equilibrium vacancy concentration and reproduced the experimentally observed low rate of the process.
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Shabashkevich, B. G. "SPECIALIZED PHOTOMETER FOR MONITORING THE BRIGHTNESS AND ILLUMINATION OF THE ROAD SURFACE". Optoelektronìka ta napìvprovìdnikova tehnìka 57 (30 de diciembre de 2022): 71–81. http://dx.doi.org/10.15407/iopt.2022.57.071.
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A specialized optical system for the Ekotensor-03 photometer was developed and based on it, the concept of direct measurements of the distribution of the brightness of the road surface, created, among other things, by LED light sources, was built. The specialized photometer (brightness meter), with readings directly in brightness units, was created on the basis of the Ekotensor-03 photometer of Ukrainian production, equipped with the appropriate optical system and mechanical devices. At the same time, instead of measuring brightness at a distance of 160 m at an angle of the receiver's field of view of 2 arc minutes vertically and 20 horizontally, it is suggested to bring the photometer closer to the illuminated planes, the brightness of which is determined, at a distance that eliminates the contradiction associated with the requirements of the DSTU and the problem of a small signal level generated by the photometric head at a long distance from the measurement object is removed. Taking into account the ultra-low levels of brightness during measurement in accordance with the requirements of the current DSTU and DBN, which is an obstacle even when carrying out measurements in controlled laboratory conditions of leading research centers, the proposed method has all the necessary advantages (high measurement accuracy, ease of implementation in non-laboratory (real) conditions, adaptability of the measurement model to the requirements of regulatory documents). The brightness measurement range of the photometer with a specialized optical system is from 0.1 Kd/m2 to 105 Kd/m2. The limits of the permissible main relative error of brightness measurement created by an arbitrary source do not exceed ± 5%. The uncertainty of calibration is 1.5%. The metrological support of the device is implemented with traceability to the national standards of the NSC "Institute of Metrology", in particular, to the primary standard of the unit of light power.
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Chen, Chen-Wei y Yi-Fan Lu. "Computational Fluid Dynamics Study of Water Entry Impact Forces of an Airborne-Launched, Axisymmetric, Disk-Type Autonomous Underwater Hovering Vehicle". Symmetry 11, n.º 9 (2 de septiembre de 2019): 1100. http://dx.doi.org/10.3390/sym11091100.
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An autonomous underwater hovering vehicle (AUH) is a novel, dish-shaped, axisymmetric, multi-functional, ultra-mobile submersible in the autonomous underwater vehicle (AUV) family. Numerical studies of nonlinear, asymmetric water entry impact forces on symmetrical, airborne-launched AUVs from conventional single-arm cranes on a research vessel, or helicopters or planes, is significant for the fast and safe launching of low-speed AUVs into the target sea area in the overall design. Moreover, a single-arm crane is one of the important ways to launch AUVs with high expertise and security. However, AUVs are still subject to a huge load upon impact during water entry, causing damage to the body, malfunction of electronic components, and other serious accidents. This paper analyses the water entry impact forces of an airborne-launched AUH as a feasibility study for flight- or helicopter-launched AUHs in the future. The computational fluid dynamics (CFD) analysis software STAR-CCM+ solver was adopted to simulate AUH motions with different water entry speeds and immersion angles using overlapping grid technology and user-defined functions (UDFs). In the computational domain for a steady, incompressible, two-dimensional flow of water with identified boundary conditions, two components (two-phase flow) were modeled in the flow field: Liquid water and free surface air. The variations of stress and velocity versus time of the AUH and fluid structure deformation in the whole water entry process were obtained, which provides a reference for future structural designs of an AUH and appropriate working conditions for an airborne-launched AUH. This research will be conducive to smoothly carrying out the complex tasks of AUHs on the seabed.
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Oliveira, Ana Elisa F., Arnaldo César Pereira, Mayra A. C. Resende y Lucas Franco Ferreira. "Gold Nanoparticles: A Didactic Step-by-Step of the Synthesis Using the Turkevich Method, Mechanisms, and Characterizations". Analytica 4, n.º 2 (8 de junio de 2023): 250–63. http://dx.doi.org/10.3390/analytica4020020.
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In this study, gold nanoparticles (AuNPs) were synthesized using the Turkevich method. This article explains the didactic step-by-step synthesis, showing pictures of the entire process, including a well-explained mechanism and characterization study. Synthesis involves the reduction of NaAuCl4 using sodium citrate at high temperatures (approximately 90 °C). The two main mechanisms used to explain AuNPs synthesis via the Turkevich method are also discussed. The first mechanism considers that a nanowire intermediary and the other proposes that aggregate intermediates are not formed at any time during the synthesis. The materials (NaAuCl4 and AuNPs) were characterized using UV-Vis spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and dynamic light scattering (DLS). The UV-Vis spectrum exhibits an absorption maximum at 521 nm because of the surface plasmon resonance (SPR) absorption band of the AuNPs. The SEM images of NaAuCl4 show crystals with cubic shapes, while the AuNPs have an average particle size of approximately 16–25 nm and particles that appear mainly spherical. To confirm the particle shapes, AFM was conducted, and it was possible to clearly observe individual spherical nanoparticles and their aggregates, and the average diameter of these AuNPs was approximately 12–19 nm. The XRD pattern of AuNPs showed four main characteristic peaks corresponding to the (111), (200), (220), and (311) planes, confirming the presence of cubic (FCC) gold. The DLS presented an average particle size of 3.3 ± 0.9 nm and a polydispersity index (PDI) of 0.574. AuNPs were synthesized using a simple and rapid method. The resulting spherical and ultra-small particles can be used in several applications.
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Hermann, Sascha, Simon Böttger y Martin Hartmann. "(Invited) Suspended 1D/2D Nanomaterials: Progress on a Waferlevel Technology and Applications". ECS Meeting Abstracts MA2023-02, n.º 30 (22 de diciembre de 2023): 1530. http://dx.doi.org/10.1149/ma2023-02301530mtgabs.
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The use of 1D and 2D nanomaterials in emerging electronics and sensor technologies is becoming increasingly important due to their unique properties. Here we would like to highlight a scalable process for suspended nanomaterials that provides additional scope for the development of device properties that can be used in advanced concepts ranging from molecular sensing to quantum applications [1]. For example those applications benefit from arrangements as CNT-based nanoresonators with extremely high quality factors [2] usable for quantum bits with long coherence time [3] or suspended sensing nanomaterials for ultra-low power and extremely sensitive gas sensors [4]. Moreover, straining allows to tune intrinsic physical properties of nanomaterials. Thus, the strain-dependence of the band gap (e.g. CNTs <100meV/% [5], MoS2 ~60meV/% [6],) paves the way for integrated-, highly-efficient-, and tunable light sources for on-chip spectrometry in the context of photonic integrated circuits (PICs), as recently reviewed in [7]. Our technological solution to manufacture suspended nanomaterials is aligned with established semiconductor processing chains on 200 mm wafer level and is developed to be modular integrable and compatible with MEMS, MEOMS or CMOS technologies [8]. Along the process chain, we demonstrate wafer-validated deposition processes for semiconducting CNT films which properties can be adjusted with respect to density and even alignment. In particular, for straining aligned CNTs as well as any transferable 2D nanomaterial, we implemented a stressed functional SiO2/SiN layer stack arranged on embedded sacrificial Cu-structures on the wafer surface. After contacting of the nanomaterial and release of sacrificial elements, stressed layers relax, strain and suspend the nanomaterial. This surface engineering approach greatly simplifies the introduction of strain into nanomaterials and makes it accessible for arbitrary device numbers on wafers as well as for monolithic 3D electronic concepts. Unique features include in-plane strains that are applicable in multiaxial directions and can be controlled by designing only two lithography planes. We show that devices with CNTs strained up to 1% determined from Raman spectral analysis, have a positive impact on sensor operation. We show application examples such as a mechanical stress sensor with extremely low on-set sensitivity. References [1] A. Baydin, F. Tay, J. Fan, M. Manjappa, W. Gao, and J. Kono, “Carbon Nanotube Devices for Quantum Technology,” Materials (Basel, Switzerland), vol. 15, no. 4, 2022. [2] J. Moser, A. Eichler, J. Güttinger, M. I. Dykman, and A. Bachtold, “Nanotube mechanical resonators with quality factors of up to 5 million,” Nature Nanotechnology, vol. 9, no. 12, pp. 1007–1011, 2014. [3] I. Khivrich and S. Ilani, “Nanotubes resound better,” Nature Nanotech, vol. 9, no. 12, pp. 963–964, 2014. [4] D.-H. Baek, J. Choi, and J. Kim, “Fabrication of suspended nanowires for highly sensitive gas sensing,” Sensors and Actuators B: Chemical, vol. 284, pp. 362–368, 2019. [5] L. Yang and J. Han, “Electronic structure of deformed carbon nanotubes,” Physical review letters, vol. 85, no. 1, pp. 154–157, 2000. [6] C. R. Zhu et al., “Strain tuning of optical emission energy and polarization in monolayer and bilayer MoS${}_{2}$,” Phys. Rev. B, vol. 88, no. 12, p. 121301, 2013. [7] M. Pandey, C. Pandey, R. Ahuja, and R. Kumar, “Straining techniques for strain engineering of 2D materials towards flexible straintronic applications,” Nano Energy, vol. 109, p. 108278, 2023. [8] S. Bottger, F. Dietz, M. Hartmann, N. Dahra, E. Kaulfersch, and S. Hermann, “Functional CMOS extension with integrated carbon nano devices,” in 2022 Smart Systems Integration (SSI): 27-28 April 2022, Grenoble, France, 2022, pp. 1–4.
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Dunlop, Erik C., David S. Warner, Prue E. R. Warner y Louis R. Coleshill. "Ultra-deep Permian coal gas reservoirs of the Cooper Basin: insights from new studies". APPEA Journal 57, n.º 1 (2017): 218. http://dx.doi.org/10.1071/aj16015.
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There is a vast, untapped gas resource in deep coal seams of the Cooper Basin, where extensive legacy gas infrastructure facilitates efficient access to markets. Proof-of-concept for the 5 million acre (20 000km2) Cooper Basin Deep Coal Gas (CBDCG) Play was demonstrated by Santos Limited in 2007 during the rise of shale gas. Commercial viability on a full-cycle, standalone basis is yet to be proven. If commercial reservoirs in nanoDarcy matrix permeability shale can be manufactured by engineers, why not in deep, dry, low-vitrinite, poorly cleated coal seams having comparable matrix permeability but higher gas content? Apart from gas being stored in a source rock reservoir format, there is little similarity to other unconventional plays. Without an analogue, development of an optimal reservoir stimulation technology must be undertaken from first principles, using deep coal-specific geotechnical and engineering assumptions. Results to date suggest that stimulation techniques for other unconventional reservoirs are unlikely to be transferable. A paradigm shift in extraction technology may be required, comparable to that devised for shale reservoirs. Recent collaborative studies between the South Australian Department of State Development, Geological Survey of Queensland and Geoscience Australia provide new insight into the hydrocarbon generative capacity of Cooper Basin coal seams. Sophisticated regional modelling relies upon a limited coal-specific raw dataset involving ~90 (5%) of the total 1900 wells penetrating Permian coal. Complex environmental overprints affecting resource concentration and gas flow capacity are not considered. Detailed resource estimation and the detection of anomalies such as sweet spots requires the incorporation of direct measurement. To increase granularity, the authors are conducting an independent, basin-wide review of underutilised open file data, not yet used for unconventional reservoir purposes. Reservoir parameters are quantified for seams thicker than 10feet (3m), primarily using mudlogs and electric logs. To date, ~3750 reservoir intersections are characterised in ~1000 wells. Some parameters relate to resource, others to extraction. A gas storage proxy is generated, not compromised by desorption lost gas corrections. A 2016 United States Geological Survey resource assessment, based on Geoscience Australia studies, suggests that the Play remains a world-class opportunity, despite being technology-stranded for the past 10years. Progress has been made in achieving small but incrementally economic flow rates from add-on hydraulic fracture stimulation treatments inside conventional gas fields. Nevertheless, a geology/technology impasse precludes full-cycle, standalone commercial production. A review of open file data and cross-industry literature suggests that the root cause is the inability of current techniques to generate the massive fracture network surface area essential for high gas flow. Coal ductility and high initial reservoir confining stress are interpreted to be responsible. Ultra-deep coal reservoirs, like shale reservoirs, must be artificially created by a large-scale stimulation event. Although coal seams fail the reservoir ‘brittleness test’ for shale reservoir stimulation practices, the authors conclude from recent studies that pervasive, mostly cemented or closed coal fabric planes of weakness may instead be reactivated on a large scale, to create a shale reservoir-like stimulated reservoir volume (SRV), by mechanisms which harness the reservoir stress reduction capacity of desorption-induced coal matrix shrinkage.
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AIB, Ekejiuba. "Universal “Plug and Play” Real-Time Entire Automotive Exhaust Effluents, Industry Vents and Flue Gas Emissions Liquefiers: The Game Changer Approach-Phase Two Category". Petroleum & Petrochemical Engineering Journal 7, n.º 2 (4 de abril de 2023): 1–56. http://dx.doi.org/10.23880/ppej-16000349.
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The first in the series of Azuberths Game Changer publications “Synergy of the Conventional Crude Oil and the FT-GTL Processes for Sustainable Synfuels Production: The Game Changer Approach-Phase One Category” a.k.a. (DOI: 10.23880/ppej16000330) is targeted at reducing 80 per cent CO2 emissions from the internal combustion engines by upgrading from the conventional crude oil refinery products to the synthetic fuels products (ultra-low-carbon fuels). This paper will focus on the complete elimination of the remaining 20 per cent CO2 emissions (i.e. to achieve zero- CO2 emissions) in transportation and power generating internal combustion engines as well as in the other centralized emissions/emitters such as petroleum industry flare lines, industrial process and big technology industries scrubber flue gas, et cetera. This invention stems from similar biblical quote {Isaiah 6:8-New International Version (NIV)} which states, and then I heard the voice of the Lord saying, “Whom shall I send? And who will go for us?” And I (Isaiah) said, “Here am I. Send me!” Laterally, in this case I (Azunna) said, “Here am I. Please use me”. Hence the aftermath, IJN-Universal Emissions Liquefiers is a plug and play units for all categories of pollutants discharge into the atmosphere. The work is motivated by the scientific facts that (i) The release of CO2 from automotive exhaust effluents, industry vents and flue gas emissions into the atmosphere contributes to greenhouse gas (GHG) accumulation causing global warming hence climate changes issues such as flooding of coastlines/sea-rising, melting of the glaciers, disrupted weather patterns, bushburning/wildfire, depletion of Ozone layer, smog and air pollution, acidification of water bodies, runaway greenhouse effect, etc. (ii) Every gas stream (e.g., flue gas) can be made liquid by e.g. a series of compression, cooling and expansion steps and once in liquid form, the components of the gas can be separated in a distillation column. (iii) Captured liquefied gases can be put to various uses, especially carbon dioxide (CO2 ), which can be used for the production of renewable energy via Synfuels such as the e-fuel/solar fuel. The natural atmosphere is composed of 78% nitrogen, 21% oxygen, 0.9% argon, and only about 0.1% natural greenhouse gases, which include carbon dioxide, organic chemicals called chlorofluorocarbons (CFCs), methane, nitrous oxide, ozone, and many others. Although a small amount, these greenhouse gases make a big difference - they are the gases that allow the greenhouse effect to exist by trapping in some heat that would otherwise escape to space. Carbon dioxide, although not the most potent of the greenhouse gases, is the most important because of the huge volumes emitted into the air by combustion of fossil fuels (e.g., gasoline, diesel, fuel oil, coal, natural gas). In general, the major contributors to the greenhouse effect are: Burning of fossil fuels in automobiles, deforestation, farming processing and manufacturing factories, industrial waste and landfills, increasing animal and human respiration, etc. The increased number of factories, automobiles, and population increases the amount of these gases in the atmosphere. The greenhouse gases never let the radiations to escape from the earth atmosphere and increase the surface temperature of the earth. This then leads to global warming. The petroleum industry well sites vent/flare gases (methane, ethane, propane, butanes, H2 O (g), O2 , N2 , etc.). Internal combustion engines (automobiles-cars, vehicles, ships, trains, planes, etc.) release exhaust effluents (containing H2 O (g), CO2 , O2 , and N2 ); steam generators in large power plants and the process furnaces in large refineries, petrochemical and chemical plants, and incinerators burn considerable amounts of fossil fuels and therefore emit large amounts of flue gas to the ambient atmosphere. In general, Flue gas is the gas exiting to the atmosphere via a “flue”, which is a pipe or channel for conveying exhaust gases from a fireplace, oven, furnace, boiler or steam generator. The emitted flue gas contains carbon dioxide CO2 , carbon monoxide CO, sulphur oxide SO2 , nitrous oxide NO and particulates. Furthermore, GTL plants produce CO2 , H2 O and waste heat, while both pyrolysis and gasification plant generate gaseous products consisting of (a mixture of non-condensable gases such as H2 , CO2 , and CO and light hydrocarbons “e.g. CH4 ” at room temperature, as well as H2 O (g), O2 and complex hydrocarbons e.g. C2 H2 , C2 H4 , etc.). In general, all combustion is as a result of air-fuel mixture burning (i.e. air or oxygen mixing directly with biomass/ coal or with liquid/gaseous hydrocarbon inside internal combustion engines), releases carbon dioxide and steam (H2 O) back into the atmosphere as well as producing energy for work. Specifically, during combustion, carbon combines with oxygen to produce carbon dioxide (CO2 ). The principal emission from transportation and power generating internal combustion engines is carbon dioxide (CO2 ). The level of CO2 emission is linked to the amount of fuel consumed and the type of fuel used as well as the individual engine’s operating characteristics. For instance, diesel-powered engines have higher emission than petrol/gasoline-powered engines. Although emphasis is places more on CO2 , this investigation is ultimately concerned with the real-time liquefaction of all the components of gaseous release/emissions -related to air pollution/health problem. It is believed that the mortality rate from air pollution is eight times larger than the mortality caused by car accidents each year. Pollutants with the strongest evidence for public health concern include particulate matter (PM), ozone (O3 ), nitrogen dioxide (NO2 ) and sulphur dioxide (SO2 ). All the exhaust effluents gases/flue gas and vent/flare gases are captured by liquefying them and then put to various uses, to achieve “Net zero” emissions. Fundamentally, the objective of the present invention is to develop a compact device (Universal Emissions Liquefiers) that can be retro-fitted onto the exhaust tailpipe-end of the internal combustion engines (diesel-powered, gasoline-powered, and hybrid automobiles-cars, vehicles, SUV’s, trucks, motor cycles, tri-cycles, portable electric generators, sea and cargo ships/ boats, trains, planes, rockets, etc.) and outlet of industrial machines that release flue gases through exhaust/scrubber channels, as well as crude oil, refined products storage tanks that vent greenhouse gases into the atmosphere, coal processing units/ plants and turn them into liquid { CO2 (l), N2 (l), O2 (l), etc.} or powdered components or chemically transform them in realtime with selective catalysts to any other specific compound, e.g. treating CO2 with hydrogen gas (H2) can produce methanol (CH3 OH), methane (CH4 ), or formic acid (HCOOH), while reaction of CO2 with alkali (e.g. NaOH) can give carbonates (NaHCO3 ) and bicarbonates (Na2 CO3 ). Nitrogen (N2 ) to ammonia (NH3 ) or Hydrazine (N2 H4 ), and molecular oxygen (O2 ) to hydrogen peroxide (H2 O2 ), et cetera. Alternatively, in new automobiles designs, the universal emissions liquefiers’ device can be directly net-worked on the floor alongside the catalytic converters and may eliminate the need for muffler/silencer/resonator. This is achieved by the application of any of the five main gas capture/separation technologies: Liquid absorption, Solid adsorption, Membrane separation (with and without solvent- organic or inorganic), Cryogenic refrigeration/distillation, and Electrochemical pH-swing separation or their combination to selectively trap and liquefy the individual pollutants. According to the fact from CarBuster, almost 0.009 metric tons of carbon dioxide is produced from every gallon of gasoline burned, which means that the average car user makes about 11.7 tons of carbon dioxide each year from their cars alone
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Umezawa, K. "Low Energy Atom Scattering Spectroscopy for Insulator Surface Analysis: MgO(111) Surfaces". MRS Proceedings 1531 (2013). http://dx.doi.org/10.1557/opl.2013.83.
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ABSTRACTThis study described a low-energy atom scattering system combined with a time-of-flight spectrometer and an ultra high vacuum chamber for insulator surface structural analysis. We show one of examples to study of MgO(111) surface analysis. A visual image of Mg atoms due to the projected blocking pattern represents the crystalline structure of the MgO(111) surfaces. This figure shows the trajectory of scattered 4He0 particles due to Mg atoms along low-index lattice planes and crystallographic directions. Insulator surface structural analysis becomes more important in materials sciences.
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Smith, Kevin E., Sarnjeet S. Dhesi, Cristian B. Stagarescu, James Downes, D. Doppalapudi y Theodore D. Moustakas. "Photoemission Study of The Electronic Structure of Wurtzite Gan(0001) Surfaces". MRS Proceedings 482 (1997). http://dx.doi.org/10.1557/proc-482-787.
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AbstractThe surface electronic structure of wurtzite GaN (0001) (1 × 1) has been investigated using angle-resolved photoemission spectroscopy. Surfaces were cleaned by repeated cycles of N2 ion bombardment and annealing in ultra-high vacuum. A well-defined surface state below the top of the valence band is clearly observed. This state is sensitive to the adsorption of both activated H2 and O2, and exists in a projected bulk band gap, below the valence band maximum. The state shows no dispersion perpendicular or parallel to the surface. The symmetry of this surface state is even with respect to the mirror planes of the surface and polarization measurements indicate that it is of spz character, consistent with a dangling bond state.
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Jaklevic, R. C. y W. J. Kaiser. "Application of Scanning Tunneling Microscopy to the Study of Metals: Spectroscopy and Topography". MRS Proceedings 77 (1986). http://dx.doi.org/10.1557/proc-77-13.
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ABSTRACTThe design and performance of a scanning tunneling microscope for use in the study of metal surfaces is described. The system was designed for ultra high vacuum together with standard sample cleaning and characterization techniques. The STM provides both topographic and spectroscopie information. Topographic images of well annealed Au(lll) show very smooth planes with single atomic steps. Corrugation on the (111) planes, which is expected from reconstruction models for this surface, is not seen. Other areas show monatomic steps in the form of an ordered array with a period corresponding to that derived from previous studies. A possible alternative reconstruction mechanism is suggested by these STM data. On the same surface are steeper sloped regions with multiple steps of equal height with wide facets. Spectroscopie first derivative data for Au and Pd show peaks which correspond to surface and bulk electronic states, for both filled and unfilled cases. The energy values of these states are compared directly with the results of other experimental methods. The use of combined topographic and spectroscopie mode for metals is anticipated.
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Abdi, Ata, Majid Seyed Salehi, Seyed Ali Fatemi, Luca Iuliano y Abdollah Saboori. "Microstructure-induced anisotropic tribological properties of Sc-Zr modified Al–Mg alloy (Scalmalloy®) produced via laser powder bed fusion process". International Journal of Advanced Manufacturing Technology, 2 de diciembre de 2023. http://dx.doi.org/10.1007/s00170-023-12691-5.
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AbstractIn this study, the correlation between the microstructure and tribological performance of Sc and Zr-modified Al–Mg alloy (Scalmalloy®) samples produced via laser powder bed fusion process was evaluated via a dry sliding Pin-on-Disc wear test under different planes, directions, and various normal applied loads. The results revealed a remarkable dependency of wear properties on the as-built microstructure so that different behaviors were observed along the scanning and building planes. The microstructural examination indicated the presence of bi-modal grains and finely shaped equiaxed grains observed in the building and scanning planes, respectively. Increasing the applied loads from 20 to 40 N led to a significant increase in the coefficient of friction (COF) while increasing the load from 40 to 60 N, slightly decreasing the COF for the studied samples. No dependency was found between the COF and the corresponding microstructure at the highest applied load. The anisotropic wear resistance and COF values were predominant at the lowest applied load. Due to tailored as-built microstructural features and different microhardness values, lower wear rates were noticed along the scanning plane for all applied loads. Under the 20 N applied load, however, the worn surface of the scanning plane showed a clearer and smoother surface compared to the building plane surfaces. Ultra-fine equiaxed grains along the scanning plane and columnar grains along the building plane were determined as the main factors creating anisotropic tribological behavior. The outcomes of this study can pave the way toward producing more wear-resistant surfaces and developing components for critical wear applications in as-built conditions with no need for expensive and time-consuming surface treatments.
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Franceschi, Giada, Pavel Kocán, Andrea Conti, Sebastian Brandstetter, Jan Balajka, Igor Sokolović, Markus Valtiner et al. "Resolving the intrinsic short-range ordering of K+ ions on cleaved muscovite mica". Nature Communications 14, n.º 1 (13 de enero de 2023). http://dx.doi.org/10.1038/s41467-023-35872-y.
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AbstractMuscovite mica, KAl2(Si3Al)O10(OH)2, is a common layered phyllosilicate with perfect cleavage planes. The atomically flat surfaces obtained through cleaving lend themselves to scanning probe techniques with atomic resolution and are ideal to model minerals and clays. Despite the importance of the cleaved mica surfaces, several questions remain unresolved. It is established that K+ ions decorate the cleaved surface, but their intrinsic ordering – unaffected by the interaction with the environment – is not known. This work presents clear images of the K+ distribution of cleaved mica obtained with low-temperature non-contact atomic force microscopy (AFM) under ultra-high vacuum (UHV) conditions. The data unveil the presence of short-range ordering, contrasting previous assumptions of random or fully ordered distributions. Density functional theory (DFT) calculations and Monte Carlo simulations show that the substitutional subsurface Al3+ ions have an important role for the surface K+ ion arrangement.
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Su, Yanfei, Chuyun Ding, Yuyu Yao, Rao Fu, Mengfei Xue, Xiaolin Liu, Jia Lin, Feng Wang, Xueying Zhan y Zhenxing Wang. "Orietation-controlled synthesis and Raman study of 2D SnTe". Nanotechnology, 20 de septiembre de 2023. http://dx.doi.org/10.1088/1361-6528/acfb8b.
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Abstract Tin telluride (SnTe), as a narrow bandgap semiconductor material, has great potential for developing photodetectors with wide spectra and ultra-fast response. At the same time, it is also an important topological crystal insulator material, with different topological surface states on several common surfaces. Here, we introduce different Sn sources and control the growth of regular SnTe nanosheets along the (100) and (111) planes through the atmospheric pressure chemical vapor deposition (APCVD) method. It has been proven through various characterizations that the synthesized SnTe is a high-quality single crystal. In addition, the angular resolved Raman spectra of SnTe nanosheets grown on different crystal planes are first demonstrated. The experimental results showed that square SnTe nanosheets grown along the (100) plane exhibit in-plane anisotropy. At the same time, we use micro-nanofabrication technology to manufacture SnTe-based field effect transistors (FETs) and photodetectors to explore their electrical and optoelectronic properties. It has been confirmed that transistors based on grown SnTe nanosheets exhibit p-type semiconductor characteristics and have a high response to infrared light. This work provides a new approach for the controllable synthesis of SnTe and adds new content to the research of SnTe-based infrared detectors.
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Wang, Wen, Haocheng Lei y Ashu Wang. "Temperature dependence of nanoscale friction on topological insulator Bi2Se3 surfaces". Nanotechnology, 30 de mayo de 2022. http://dx.doi.org/10.1088/1361-6528/ac7473.
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Abstract Topological insulators Bi2Se3 are insulating in the bulk with unusual metallic surface states that consist of spin-polarized Dirac fermions. Although electronic properties of topological insulators have been studied extensively, the friction characteristic that is a key factor for further applications are barely known. In this study, conductive friction force microscopy (c-FFM) in ultra-high vacuum (UHV) conditions has been used to probe the nanoscale friction on freshly cleaved Bi2Se3 planes (0001) as a function of surface temperature from 105.0 K to 300.0 K. The experimental results demonstrate a nonmonotonic enhancement of dry friction with distinct friction peaks emerging at T1 = 245.0 ± K and T2 = 125.0 ± 5 K. While the width of friction peak is nearly independent of the normal force, the relative peak height increases and the peak temperature decreases with normal load. We reveal that the anomalous friction behavior is originated from the thermally activated multiple sub-contacts formation and rupture, which has been further confirmed by the velocity dependence measurements. These results on the thermally activated multiple sub-contacts formation and rupture provide a deep insight into the frictional behaviors of Bi2Se3.
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Kozubski, Rafal, Miroslaw Kozlowski, Jan Wrobel, Tomasz Wejrzanowski, Krzysztof J. Kurzydlowski, Christine Goyhenex, Veronique Pierron-Bohnes, Marcus Rennhofer y Savko Malinov. "Atomic Ordering in Nano-layered FePt: Multiscale Monte Carlo Simulation". MRS Proceedings 1177 (2009). http://dx.doi.org/10.1557/proc-1177-z09-03.
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AbstractCombined nano- and mesoscale simulation of chemical ordering kinetics in nano-layered L10 AB binary system was performed. In the nano- (atomistic) scale Monte Carlo (MC) technique with vacancy mechanism of atomic migration was implemented with diverse system models. The mesoscale microstructure evolution was, in turn, modeled by means of MC procedure simulating antiphase boundary (APB) motion as controlled by APB energies evaluated within the nano-scale simulations. The study addressed FePt thin layers considered as a material for ultra-high density magnetic storage media and revealed metastability of the L10 c-variant superstructure with monoatomic planes parallel to the (001) free surface and off-plane easy magnetization. The layers, initially perfectly ordered in the L10 c-variant, showed homogenous disordering running in parallel with a spontaneous re-orientation of the monoatomic planes into a mosaic-microstructure composed of L10 a- and b-variant domains with (100)- and (010)-type monoatomic planes, respectively. The domains nucleated heterogeneously on the Fe free surface of the layer, grew discontinuously inwards its volume and finally relaxed generating an equilibrium microstructure of the system. Two �atomistic-scale� processes: (i) homogenous disordering and (ii) nucleation of the L10 a- and b-variant domains showed characteristic time scales. The same was observed for the meso-scale processes: (i) heterogeneous L10 variant domain growth and (ii) domain microstructure relaxation. The above phenomena modelled within the present study by means of multiscale MC simulations have recently been observed experimentally in epitaxially deposited thin films of FePt.
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Rou, Shang H., Philip D. Hren, John J. Hren, Thomas M. Graettinger, Michael S. Ameen, Orlando H. Auciello y Angus I. Kingon. "High Resolution Imaging of Twin and Antiphase Domain Boundaries in Perovskite KNbO3 Thin Films." MRS Proceedings 183 (1990). http://dx.doi.org/10.1557/proc-183-285.
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AbstractPerovskite KNbO 3 thin films were heteroepitaxially deposited onto (100) MgO substrates. Twin domains with tetrahedral shape were typically observed. These tetrahedrons were bounded by three {211} twin planes. High resolution transmission electron microscopy (HRTEM) was employed to examine these {211} twin boundaries. Surface steps of {110}<110> type generated by dislocation slip were present on the MgO substrate. The tetrahedral twin domains originate on surface steps, then grow with a stacking fault relationship to the matrix. The strain fields of dislocations near the stacking faults slightly rotate the tetrahedral twin nuclei. This small degree of misalignment between the matrix and the twin domain result in some of the twin boundaries having amorphous boundary regions rather than coherent interfaces.Order-disorder antiphase domains (APD's) were directly imaged with HRTEM. Ultra small APD's ranging from 10 to 30 atomic spacings were observed. The origin of these APD's was either the surface steps of {100} <1 10> type on MgO substrates or the random nucleation of anions at either of two equivalent sites on the MgO substrate.
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Stangerlin, Diego Martins, Joaquim Carlos Gonçalez, Raquel Gonçalves, Elio José Santini, Leandro Calegari, Rafael Rodolfo de Melo y Darci Alberto Gatto. "AVALIAÇÃO DE TIPOS DE ONDAS GERADAS POR DOIS MODELOS DE TRANSDUTORES PARA DETERMINAÇÃO DO MÓDULO DE ELASTICIDADE DINÂMICO". FLORESTA 40, n.º 4 (23 de diciembre de 2010). http://dx.doi.org/10.5380/rf.v40i4.20320.
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O objetivo deste estudo foi de avaliar os tipos de ondas gerados por dois modelos de transdutores utilizados para determinação do módulo de elasticidade dinâmico por meio de ensaios com ultrassom e correlacioná-los ao módulo de elasticidade estático obtido por compressão paralela às fibras. Para tanto, utilizou-se um aparelho de ultrassom dotado de transdutores faces planas e de pontos secos com freqüência de 50 kHz. A velocidade ultra-sônica foi determinada ao considerar a transmissão da onda ao longo do comprimento de amostras de madeira com dimensões nominais de 5 x 5 x 20 cm. Para avaliar a sensibilidade do método ultra-sonoro e os tipos de ondas gerados pelos respectivos transdutores, as amostras foram ensaiadas destrutivamente à compressão paralela, com determinação do módulo de elasticidade por ambas metodologias. Apesar da diferença de valores absolutos do módulo de elasticidade entre os ensaios de ultrassom com transdutores faces planas, que geraram ondas longitudinais, e os ensaios de compressão paralela, em função da natureza viscoelástica da madeira, verificou-se uma boa correlação entre os dados. Com relação ao uso dos transdutores pontos secos, que geraram ondas de superfície, não foi verificada boa correlação com os ensaios destrutivos.Palavras-chave: Ondas longitudinais; ondas de superfície; transdutores de faces planas; transdutores de pontos secos; ensaios não-destrutivos. AbstractEvaluation of wavess generated for two models of transducers for determining the dynamic modulus of elasticity. This study aimed to evaluate the types of waves generated for two transducers used for determining the dynamic modulus of elasticity by tests with ultrasound and to correlate them to the static modulus of elasticity obtained by parallel compression. For this study ultrasonic equipment with planes faces and point-contact transducers of 50 kHz was used. The ultrasonic speed was determined considering the transmission of the wave along the length of the samples with nominal dimensions of 5 x 5 x 20 cm. To evaluate the sensitivity of the ultrasonic method and the types of waves generated for the transducers, samples were submitted to destructive conventional parallel compression, with determination of the elasticity modulus for both methodologies. Although the difference of absolute values between tests of ultrasound with transducers planes faces, that generated longitudinal waves, and parallel compression, due to wood viscoelastic nature, there was a good correlation between the obtained data. It was not observed good correlation between the use of point-contact transducers, which generated surface waves, and the destructive tests.Keywords:Longitudinal waves; surface waves; planes faces transducers; point-contact transducers; not-destructive methods.
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Shingubara, S., H. Sukesako, T. Kawasaki, K. Inoue, Y. Matusi, H. Sakaue, T. Takahagi y Y. Horiike. "Tem Observation of the Damages in Heavily Ion-Implanted Fine Si Columns". MRS Proceedings 354 (1994). http://dx.doi.org/10.1557/proc-354-641.
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AbstractSi nanometer structures are promising for exhibiting the quantum size effect at temperatures even as high as a room temperature. The present work investigates by TEM the damages induced by a heavy ion-implantation to the fine Si columns, aim of fabrication of 1-D tunneling PN diode in future. Si columns are fabricated by electron beam lithography and reactive ion etching, followed by thinning by thermal oxidation of Si . Ultra fine Si column with a diameter of 8 nm are successfully formed. TEM lattice image observations for fine Si columns, which are subject to ion-implantation and subsequent annealing, are carried out. In the case of heavy doping of As, as well as BF2, as-doped structure is amorphous, and recrystallization is observed after annealing at 1000 °C for 30 min. Typical damages such as dislocations which are parallel to the {111} planes and Si micro-crystals which are differently oriented from the Si single crystal substrate are observed for Si columns with diameters larger than 40nm. However, it should be noted that no damage is observed for fine Si columns with diameters less than 20nm. It is suggested that defects are diffused out to the surface or the Si/SiO2 interface for ultra fine Si columns during annealing.
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Capuano, Luigo, J. W. Berenschot, Roald M. Tiggelaar, Matthias Feinaeugle, Niels R. Tas, Han J. G. E. Gardeniers y Gert-Willem R. B. E. Römer. "Fabrication of Microstructures in the Bulk and on the Surface of Sapphire by Anisotropic Selective Wet Etching of Laser Affected Volumes". Journal of Micromechanics and Microengineering, 11 de octubre de 2022. http://dx.doi.org/10.1088/1361-6439/ac9911.
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Abstract In this paper a processing technique for sapphire is presented which combines laser-induced amorphization and subsequent selective wet etching of amorphized sapphire as well as anisotropic wet etching of single-crystalline sapphire (α-Al2O3). Using this technique, microstructures can be realized on the surface and in the bulk of sapphire substrates. By focusing ultra-short laser pulses inside sapphire, its structure can be transformed from crystalline into amorphous. The modified material can be selectively removed using etchants, such as hydrofluoric acid (HF) or potassium hydroxide (KOH), solely dissolving the amorphized part. In this work, however, an etchant consisting of a standard solution of sulphuric acid and phosphoric acid (96 vol% H2SO4 : 85 vol% H3PO4, 3:1 vol%) at 180 °C is utilized. This method allows the realization of structures which are impossible to achieve when using conventional etchants which solely dissolve the amorphized sapphire. Ultrashort pulsed laser irradiation (230 fs) is used in this study as starting point for the subsequent anisotropic etching to form microstructures on the surface or in the bulk of sapphire that are terminated by characteristic crystal planes. In particular, the appearance of etching-induced patterns formed by stacks of rhombohedra is shown for structures below the surface, whereas triangular pits are achieved in surface processing.
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Pramanik, Sudipta, Jan Krüger, Mirko Schaper y Kay-Peter Hoyer. "Quasi-In Situ Localized Corrosion of an Additively Manufactured FeCo Alloy in 5 Wt Pct NaCl Solution". Metallurgical and Materials Transactions A, 10 de septiembre de 2023. http://dx.doi.org/10.1007/s11661-023-07186-7.
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AbstractFeCo alloys are important materials used in pumps and motors in the offshore oil and gas drilling industry. These alloys are subjected to marine environments with a high NaCl concentration, therefore, corrosion and catastrophic failure are anticipated. So, the surface dissolution of additively manufactured FeCo samples is investigated in a quasi-in situ manner, in particular, the pitting corrosion in 5.0 wt pct NaCl solution. The local dissolution of the same sample region is monitored after 24, 72, and 168 hours. Here, the formation of rectangular and circular pits of ultra-fine dimensions (less than 0.5 µm) is observed with increasing immersion time. In addition, the formation of a corrosion-inhibiting surface layer is detected on the sample surface. Surface dissolution leads to a change in the surface structure, however, no change in grain shape or grain size is noticed. The surface topography after local dissolution is correlated to the grain orientation. Quasi-in situ analysis shows the preferential dissolution of high-angle grain boundaries (HAGBs) leading to a change in the fraction of HAGBs and low-angle grain boundaries fraction (LAGBs). For the FeCo sample, a potentiodynamic polarisation test reveals a corrosion potential (Ecorr) of − 0.475 V referred to the standard hydrogen electrode (SHE) and a corrosion exchange current density (icorr) of 0.0848 A/m2. Furthermore, quasi-in situ experiments showed that grains oriented along certain crystallographic directions are corroding more compared to other grains leading to a significant decrease in the local surface height. Grains with a plane normal close to the $$\langle {1}00\rangle$$ ⟨ 100 ⟩ direction reveal lower surface dissolution and higher corrosion resistance, whereas planes normal close to the $$\langle {11}0\rangle$$ ⟨ 110 ⟩ direction and the $$\langle {111}\rangle$$ ⟨ 111 ⟩ direction exhibit a higher surface dissolution.
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d'Anterroches, C., F. Houzay y M. Bensoussan. "Structure Analysis of the Al-Inp (100) Interface". MRS Proceedings 94 (1987). http://dx.doi.org/10.1557/proc-94-237.
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ABSTRACTHigh Resolution Electron Microscopy (HREM) images of the Al/InP interface were obtained from as-deposited films. The high purity Al films were deposited onto a clean (100) InP surface in a Molecular Beam Epitaxy (MBE) chamber. The in situ Reflection High Energy Electron Diffraction (RHEED) and Ultra-Violet Photoemission Spectroscopy (UPS) analyses showed a transformation of the InP surface during the Al deposition. The UPS data are interpreted as a strong exchange reaction between incoming Al and substrate In atoms. The In atoms are released and recover metallic behavior while Al atoms are involved in covalent bonds. At high coverages the RHEED analysis shows an epitaxial relationship in between Al and InP such as (110)Al//(100)InP with the two variants: [001]Al//[011]InP and [001]Al//[0–11]InP. The HREM images show that the interface AI/InP is perturbed and an intermediate layer is found. This layer appears to have the same crystal structure as InP indicated by extension of atomic planes from InP to the layer. However, the observed intensity, which corresponds to the mean potential of the forming atoms, is lighter than that of InP. Hence,out of these HREM and UPS results it is derived that an AlP or AlxIn1−xP compound is located at the Al/InP interface.
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Saka, Abel, Leta Tesfaye Jule, Shuma Soressa, Lamessa Gudata, N. Nagaprasad, Venkatesh Seenivasan y Krishnaraj Ramaswamy. "Biological approach synthesis and characterization of iron sulfide (FeS) thin films from banana peel extract for contamination of environmental remediation". Scientific Reports 12, n.º 1 (21 de junio de 2022). http://dx.doi.org/10.1038/s41598-022-14828-0.
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AbstractBiological approach synthesis and characterization of Iron Sulfide (FeS) thin films from banana peel extract for contamination remediation of environment studied. Iron chloride, Sodium thiosulfate and Ethylene-di-amine-tetra acetate (EDTA) were used as precursor solutions without further purification. The nanoparticle of banana peel was extracted and prepared with synthesized FeS thin films and analyzed by X ray-diffraction for structural examination, Scanning electron microscope (SEM) for surface morphological analysis, Ultra-violet-visible-spectrometer (UV–Vis) and photo-luminescence spectro-photo-meter (P-L) for optical characterizations. XRD peaks are shown with recognized to (110), (200), (310), and (301) crystalline planes. The occurrence of this deflection peak are recognised the FeS crystal segment of the tetragonal crystalline systems. SEM micrographs of the films prepared biological method show the distribution of grains, which cover the surface of the substrate completely and are uniform and films deposited purely have defects. The photo-luminescence, absorbance, and transmittance strength of banana peel extract FeS thin film is greater than pure FeS thin films in which wide-ranging and symmetries groups were perceived. In the present study, the comparison of pure FeS thin films and Nano synthesized banana peel extract with FeS thin films was studied. It is observed that Nano synthesized banana fibre absorbs higher than pure FeS thin films in solar cell application. Finally, green synthesis is an ecofriendly, easy and cheap promising method for the fabrication of thin films for solar cell applications.
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Kumaria, Sneha, Pandey, Shivam, Leela Manohar Aeshala, Anuj Kumar y Sushant Singha. "Augmenting Antioxidative Properties of Cerium Oxide Nanomaterial with Andrographis paniculata Mediated Synthesis and Investigating its Biomedical Potentials." Nanofabrication 9 (22 de abril de 2024). http://dx.doi.org/10.37819/nanofab.9.1807.
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Extensive interest has been poured into the production of sustainable nanomaterials. We report the fabrication of cerium oxide nanomaterial (CNP)utilizing crude extracts of Andrographis paniculata. This synthesis route devises a sustainable approach with the implementation of a less energy-intensive process and avoids hazardous chemicals. The crude extracts of Andrographis paniculata (cAP) act simultaneously as a reducing and stabilizing agent and support the nucleation of CNP leading to unique physiochemical properties. The cAP-CNP conjugate is found in the size range of 150nm with signature UV peaks at 310 nm indicating Ce+4 surface oxidation state. Scanning electron microscope and X-ray diffraction analysis of cAP-CNP conjugate indicates the ultra-structure of dry powder and polycrystalline signature peaks with 111, 200, 220 and 311 crystal planes indicating pure cubic fluorite structure. Further cAP-CNP conjugate also reports high H2O2(80%)and moderate superoxide anion (40%) antioxidative scavenging. The cAP-CNPnanomaterial conjugates exhibit excellent antimicrobial behavior with a reduction of 60% E.colibacterial growth. Similarly,cAP-CNP conjugate exhibits alpha-amylase inhibition (80%) activity indicating its prospects in diabetics’management.In-vitro analysis results the biocompatibility with 85% skin keratinocyte cell growth. Anti-inflammatory assay revealed IL-6 (89%) and TNF-alpha (81%) reduced expression. Overall, cAP-CNP demonstrates a sustainable approach to prospective biomedical applications.
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Coldea, Amalia I. "Electronic Nematic States Tuned by Isoelectronic Substitution in Bulk FeSe1−xSx". Frontiers in Physics 8 (23 de marzo de 2021). http://dx.doi.org/10.3389/fphy.2020.594500.
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Isoelectronic substitution is an ideal tuning parameter to alter electronic states and correlations in iron-based superconductors. As this substitution takes place outside the conducting Fe planes, the electronic behaviour is less affected by the impurity scattering experimentally and relevant key electronic parameters can be accessed. In this short review, I present the experimental progress made in understanding the electronic behaviour of the nematic electronic superconductors, FeSe1−xSx. A direct signature of the nematic electronic state is in-plane anisotropic distortion of the Fermi surface triggered by orbital ordering effects and electronic interactions that result in multi-band shifts detected by ARPES. Upon sulphur substitution, the electronic correlations and the Fermi velocities decrease in the tetragonal phase. Quantum oscillations are observed for the whole series in ultra-high magnetic fields and show a complex spectra due to the presence of many small orbits. Effective masses associated to the largest orbit display non-divergent behaviour at the nematic end point (x ∼ 0.175(5)), as opposed to critical spin-fluctuations in other iron pnictides. Magnetotransport behaviour has a strong deviation from the Fermi liquid behaviour and linear T resistivity is detected at low temperatures inside the nematic phase, where scattering from low energy spin-fluctuations are likely to be present. The superconductivity is not enhanced in FeSe1−xSx and there are no divergent electronic correlations at the nematic end point. These manifestations indicate a strong coupling with the lattice in FeSe1−xSx and a pairing mechanism likely promoted by spin fluctuations.