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A novel meshfree weak–strong (MWS) form method is proposed based on a combined formulation of both the strong-form and the local weak-form. In the MWS method, the problem domain and its boundary is represented by a set of distributed points or nodes. The strong form or the collocation method is used for all nodes whose local quadrature domains do not intersect with natural (Neumann) boundaries. Therefore, no numerical integration is required for these nodes. The local weak-form, which needs the local numerical integration, is only used for nodes on or near the natural boundaries. The locally supported radial point interpolation method and the moving least squares approximation are used to construct the meshfree shape functions. The final system matrix will be sparse and banded for computational efficiency. Numerical examples of two-dimensional solids are presented to demonstrate the efficiency, stability, accuracy and convergence of the proposed meshfree method. 相似文献
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《Advanced Powder Technology》2022,33(9):103728
Exploration of low-cost and high efficiency oxygen evolution reaction (OER) electrocatalysts is very important for the large-scale industrial application of alkaline water splitting driven by electricity. The present promising cobalt-based catalysts still leave room to meet the activity requirement. Here, a composite catalyst of α-Co(OH)2/Ag was synthesized by a simple photochemical deposition route, which was designed to improve the electrocatalytic activity for OER. Moreover, a photoinduced surface plasmon on Ag particles was found to further enhance the catalytic performance under low power of laser irradiation. Loading of silver nanocrystals on α-Co(OH)2 nanosheets can decrease the overpotential towards OER for 10 mA cm?2 from 320 to 288 mV, this value can be further decreased of 45 mV under 1000 mW of laser irradiation with a wavelength of 532 nm. The derivation of the catalyst during the OER process was examined, which indicates the structural transformation from α-Co(OH)2 to CoOOH. The photoinduced surface plasmon modulates the electronic structure of cobalt sites, facilitates the formation of active cobalt species, and induces the enhancement of catalytic activity. These findings may give some hints for plasmon-induced electrocatalysis and the design of advanced electrocatalysts. 相似文献
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《Materials Science & Technology》2013,29(8):968-974
AbstractThe influence of long term soft milling of a mixture of (1) Mg(OH)2 and α-Fe2O3 and (2) Mg(OH)2 and Fe(OH)3 powders in a planetary ball mill on the reaction synthesis of nanosized MgFe2O4 ferrites was studied. Soft mechanochemical reaction leading to formation of the MgFe2O4 spinel phase was followed by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and magnetisation measurements. The spinel phase formation was first observed after 5 h of milling and its formation was completed after 15 h in case (2). The synthesised MgFe2O4 ferrite had a nanocrystalline structure with a crystallite size of about 10 and 15 nm respectively for cases (1) and (2). Measurements after 15 h of milling show magnetisation values of 15·23 and 10·14 J T–1 kg–1 respectively for cases (1) and (2). 相似文献
5.
Wolf C Lederer K Bergmeister H Losert U Böck P 《Journal of materials science. Materials in medicine》2006,17(12):1341-1347
Numerous investigations proved the impressive suitability of α-tocopherol as a stabilizer for ultra-high molecular weight
polyethylene (UHMW-PE) used for endoprostheses. Regarding the biocompatibility of this new biomaterial, in-vitro celltoxicity
tests gave no hint for a cyto- or genotoxic activity. In this study, animal experiments are carried out to further ensure
the biocompatibility of this biomaterial.
Thin UHMW-PE-films (20 × 6 × 0.23 mm3) were implanted subcutaneously into rats. Morphology and reactivity of surrounding connective tissue against either pure
UHMW-PE material or UHMW-PE containing α-tocopherol were studied at timed intervals (2 weeks, 3 month, and 6 month after operation)
in 3 groups of animals, each group comprising 10 animals. Parallel to these tests, material changes were investigated in these
3 groups of 10 animals at the same intervals after operation with the help of infrared spectroscopy (FTIR). Within the implantation
time, no noteworthy oxidative degradation could be observed. The amount of lost α-tocopherol due to diffusion is low enough
to ensure a lifetime stabilisation of the UHMW-PE.
The implants were all well tolerated and definitely encapsulated already 2 weeks after operation. Presence or absence of α-tocopherol
in the implants did not evince morphological differences. Therefore, negative consequences were not manifest in the presence
of α-tocopherol.
In partial fulfillment of a Ph.D. (Dr.mont.) thesis at the University of Leoben 相似文献
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Samples of untreated ultra-high molecular weight polyethylene (UHMW-PE), UHMW-PE sterilized with γ-rays in nitrogen atmosphere
(conventional UHMW-PE, widely used for articulating surfaces in endoprostheses) and UHMW-PE, which has been crosslinked by
electron beam irradiation and annealed subsequently, were stabilized with α-tocopherol and aged in air at 120∘C as well as in 10% aqueous hydrogenperoxide with 0.04 mg/ml FeCl3 as catalyst at 50∘C. The oxidative degradation was monitored with the help of infrared spectroscopy (FTIR), differential scanning calorimetry
(DSC), solubility measurements and size exclusion chromatography (SEC) and were compared to unstabilized samples. When aged
in air at 120∘C, the crosslinked UHMW-PE showed a slightly slower increase of the carbonyl (CO)-number (according to DIN 53383) in FTIR
than conventional UHMW-PE. A stabilisation with 0.4% w/w α-tocopherol resulted in an increase of lifetime by a factor of approx.
40 for all samples. Ageing in 10% aqueous H2O2 at 50∘C yielded similar results for all three unstabilised samples. The addition of the natural antioxidant α-tocopherol led to
a prolongation of lifetime by a factor of approx. 2.5. A linear loss of α-tocopherol was detected during ageing. An increase
of crystallinity as well as lamella thickness during ageing was observed with the help of DSC. The two-phase structure of
crosslinked UHMW-PE with two melting endotherms at 114∘C and 137∘C was replaced very quickly by a single melting point at 130∘C. This effect was delayed with the stabilized samples. In the solubility and SEC measurements, a severe molecular degradation
and drop of molar mass of all materials could be observed after ageing in H2O2, leading to a complete destruction and, in case of crosslinked UHMW-PE, to a serious damage of the molecular network, respectively.
in partial fulfilment of a Ph.D. (Dr.mont.) thesis at the University of Leoben 相似文献
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Kaixin Wang Xiaoyong Fan Shengjie Chen Junkai Deng Lulu Zhang Maosen Jing Julong Li Lei Gou Donglin Li Yue Ma 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(8):2206287
The α-Ni(OH)2 is regarded as one promising cathode for aqueous nickel-zinc batteries due to its high theoretical capacity of ≈480 mAh g−1, its practical deployment however suffers from the poor stability in strong alkaline solution, intrinsic low electrical conductivity as well as the retarded ionic diffusion. Herein, a 3D (three dimensional) macroporous α-Ni(OH)2 nanosheets with Co doping is designed through a facile and easily scalable electroless plating combined with electrodeposition strategy. The unique micrometer-sized 3D pores come from Ni substrate and rich voids between Co-doping α-Ni(OH)2 nanosheets can synergistically afford facile, interconnected ionic diffusion channels, sufficient free space for accommodating its volume changes during cycling; meanwhile, the Co-doping can stabilize the structural robustness of the α-Ni(OH)2 in the alkaline electrolyte during cycling. Thus, the 3D α-Ni(OH)2 shows a high capacity of 284 mAh g−1 at 0.5 mA cm−2 with an excellent retention of 78% even at 15 mA cm−2, and more than 2000 stable cycles at 6 mA cm−2, as well as the robust cycling upon various flexible batteries. This work provides a simple and efficient pathway to enhance the electrochemical performance of Ni-Zn batteries through improving ionic transport kinetics and stabilizing crystal structure of cathodes. 相似文献
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Spindle-like porous α-Fe(2)O(3) was prepared from an iron-based metal organic framework (MOF) template. When tested as anode material for lithium batteries (LBs), this spindle-like porous α-Fe(2)O(3) shows greatly enhanced performance of Li storage. The particle with a length and width of ~0.8 and ~0.4 μm, respectively, was composed of clustered Fe(2)O(3) nanoparticles with sizes of <20 nm. The capacity of the porous α-Fe(2)O(3) retained 911 mAh g(-1) after 50 cycles at a rate of 0.2 C. Even when cycled at 10 C, comparable capacity of 424 mAh g(-1) could be achieved. 相似文献
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S.B. Abitkar P.R. Jadhav N.L. Tarwal A.V. Moholkar C.E. Patil 《Advanced Powder Technology》2019,30(10):2285-2292
The α-Ni(OH)2-CNT composite films have been successfully synthesized by a simple chemical method and their supercapacitive properties were investigated by variation of CNT. The structural, compositional, morphological, wettability and electrochemical properties of the composite films were studied by using various characterization techniques. X-ray diffraction analysis revealed that the synthesized composite films are polycrystalline in nature. FT-Raman spectroscopy result showed the characteristic Raman band of CNT and α-Ni(OH)2 which confirmed the formation of α-Ni(OH)2-CNT composite. SEM micrographs showed porous microstructure of the synthesized films and hydrophilic nature of the films was confirmed from wettability studies. Furthermore, the effect of the variation of CNT on the electrochemical properties of the synthesized composite films was discussed. The electrochemical performance of the composite films was studied by using cyclic voltammetry (CV) and Galvanostatic charge–discharge (GCD) techniques. The α-Ni(OH)2-CNT composite showed highest specific capacitance of 544 F g?1 with high retention capability of 85% after 1500th cycle and excellent cycling stability. 相似文献
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Highly dispersed poly(amic acid) salt-stabilised palladium nanoparticles(PdNPs/PAAS) were synthesised via a facile reduction strategy in aqueous media at room temperature and characterised by transmission electron microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and inductively coupled plasma optical emission spectrometer. The nanoparticles were used as catalyst for Suzuki–Miyaura coupling reaction to synthesise biphenyl compounds in short reaction time and high yields under mild conditions, benefiting from highly efficient quasi-homogeneous catalytic activity. The catalyst could be recycled 5 times without obvious loss attributing to the pH response of the PAAS. 相似文献
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Wolf C Lederer K Pfragner R Schauenstein K Ingolic E Siegl V 《Journal of materials science. Materials in medicine》2007,18(6):1247-1252
Adding the natural antioxidant α-tocopherol to ultra-high molecular weight polyethylene (UHMW-PE) can remarkably delay the
oxidation of hip cups made thereof. However, α-tocopherol is likely to undergo different chemical transformations during manufacturing
and sterilization of hip cups than in human metabolism. Therefore, the biocompatibility of the putative transformation products
has to be investigated. In-vitro tests with L929 mice fibroblast-cells gave no evidence for cytotoxicity. To further ensure
the biocompatibility, in-vitro tests with human cells were carried out in this study. Two different human cell lines, one
adherent cell line, HF-SAR, and one suspension culture, GSJO, were tested on UHMW-PE-tablets (diameter: 15 mm; thickness:
2 mm; processed according to standard procedures for artificial hip-cups) with and without α-tocopherol with respect to cell
viability, proliferation and morphology by means of cell counting, WSt-1 proliferation assay and scanning electron microscopy.
Similar proliferation rates were found with both polyethylene samples. Further, we found intact morphology in light and electron
microscopy on each substrate. The morphologic characteristics of skin fibroblasts were not changed by any material. Normal
adherence and spreading of the fibroblasts was found on controls of glass, as well as on polystyrene and on stabilized and
unstabilized polyethylene. The characteristic behaviour as suspension of the GSJO cells remained unchanged. The mitochondrial
activity, as studied by WST-1 cell proliferation reagent, was identical on each substrate during the whole observation period
of 7 days.
Christian Wolf—in partial fulfillment of a Ph.D. (Dr.mont.) thesis at the University of Leoben 相似文献
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Characteristics of the precipitate α″-Fe16N2 phase have been investigated by X-ray diffraction and TEM analysis. VSM measurements give the saturation magnetization of the α″ phase. 相似文献
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A series of Ti-Al-Sn-Zr-Mo-Si-Nd alloys with various content of Al were solution treated in alpha+beta phase field and air-cooled. The precipitation of α(2) phase in cooling was investigated by transmission electron microscopic analysis. The precipitation characteristic of α(2) phase was discussed. The precipitation of α(2) phase would proceed by the nucleation and growth of α(2) phase dependent on the diffusion of Al atoms. And a comparison on the difference of precipitation of α(2) phase was carried out under the conditions of air-cooling and quenching in water. The investigation showed that the air-cooling and even quenching could supply enough time for the precipitation and growth of α(2) phase when Al content reached a certain value even though far away from the stoichiometric composition of Ti3Al. 相似文献
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Li Cheng Gao Xuejiao J. Yao Huanli Huang Huan Cui Rongli Guo Xihong Zhang Lele Liu Bing Xu Binggang Shi Weiqun Dong Jinquan Feng Lai Gao Xingfa Sun Baoyun 《Nano Research》2018,11(4):2277-2284
Nano Research - A new Gd@C2v(9)-C82·2.5(S8)·0.5(CS2) co-crystal was prepared for the first time and characterized by single-crystal X-ray diffraction (XRD). The analysis clearly showed... 相似文献
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To whom correspondence should be addressedE-mail: zhiquanliu@yahoo. com1. IntroductionIn the early 1950s, Ja.k[1] investigated the FeN binary system systematically, and discovered a"Fel6Nz as a new ordered nitride with a bet structure.In 1972, Kim and Takaha.hi[2] reported that the FeN films evaporated in an NZ atmosphere, which resulted in a polycrystalline mixture of or--Fe and crl'FeleNz, had an ultrahigh saturation magnetization.Since then, much attelltion has been paid to thestudy o… 相似文献
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We report the synthesis of sphere-like α-Ni(OH)(2) nanoarchitecture by self-assembly with the aid of hexamethylenetetramine (HMT). The α-Ni(OH)(2) nanoarchitectures, with a diameter of several micrometres, are composed of many nanoflakelets about 10?nm in thickness. The influences of the reaction temperature, time, reagent, nickel salt and pH?value on the morphology and structure of the α-Ni(OH)(2) were studied, the chemical and thermal stability are discussed, and the formation mechanism is proposed. The α-Ni(OH)(2) nanoarchitectures display a good electrochemical capacity. 相似文献
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R. Yoshizaki I. Tomitsuka K. Ueno H. Ikeda 《Journal of Low Temperature Physics》1996,105(3-4):927-932
When Ni is substituted for Cu in Bi-2212 single crystals, the in-plane resistivity is increased with maintaining the linear temperature dependence while the out-of-plane resistivity is decreased. The anisotropy parameter estimated from the angular dependence of the flux flow resistivity is also decreased from 250 for undoped sample to 80 for a sample doped with 2.4% of Ni. The doping dependence of ab and c is discussed on the basis of the t-J model and the Fermi liquid theory. 相似文献
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α–Cyclodextrin (α-CD) was found to form inclusion complexes with poly(ethylene glycol) (PEG) having a crystalline state in high yields, which have been investigated extensively in the past. Formation of an inclusion complex depends strongly on structure, molecular weight and geometry of the polymer. Development of a dicomponent inclusion complex (DIC) of PEG and α-CD in the presence of poly(vinyl alcohol) (PVA) and initiation of hexagonal crystals upon sonication have exhibited various microstructures. Formation of the new inclusion complex in PVA heavily depends on the concentration of PVA, temperature and sonication time. The complexes produced are characterized by FTIR, HNMR spectra and powder X-ray. 1HNMR of the complexes demonstrate that their stoichiometric ratio is 2:1 (two ethylene glycol units and one α-CD). X-ray patterns of PEG–α-CD complex indicate that the α-CD forms channels whereas PEG/α-CD/PVA creates cage-type structures. 相似文献