NiV/B
4
C multilayers with a small d-spacing are suitable for multilayer monochromator working at a photon energy region from 5 to 8 keV, or photon energy region from 10 to 100 keV. To investigate ...the influence of background pressure during fabrication, NiV/B
4
C multilayers with a d-spacing of 3.0 nm were fabricated by magnetron sputtering with different background pressures. The grazing incidence x-ray reflectivity (GIXR) and transmission electron microscopy (TEM) measurement illustrated the structural change that happened in NiV/B
4
C multilayers when background pressure is high. The electron dispersive x-ray spectroscopy (EDX) of NiV/B
4
C multilayer deposited with a high background pressure suggests a gradient distribution of oxygen, which corresponds to the gradient thickness change. The detailed x-ray absorption near edge spectroscopy (XANES) comparison of NiV/B
4
C multilayers, NiV coating, and B
4
C coating showed the chemical state change induced by background pressure. We concluded that during the deposition, vanadium oxide promoted the oxidation of boron. In order to fabricate a good performance of NiV/B
4
C multilayers, the background pressure needs lower than 1 × 10
−4
Pa.
Al86Ce10TM4 amorphous alloys (TM = Ti, Cr, Mn, Fe, Co, Ni and Cu; where the alloys are denoted by A1~A7, respectively) were fabricated using melt-spin fast-quenching method. The glass-forming ability ...(GFA), thermal stability (TS), and mechanical and corrosion behavior of the as-spun alloys were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy - energy dispersive spectroscopy (SEM-EDS), differential scanning calorimetry (DSC), micro-indentation and electrochemical techniques. It was found Al and Ce microalloyed with Ti, Cr, Mn, Fe, Co, Ni and Cu, respectively enhance glass formation, thus the as-spun Al86Ce10TM4 alloys form an amorphous matrix embedded with short range ordered (SRO) Al-TM, Al-Ce and Al-Ce-TM quasi-crystalline clusters due to a strong heteroatomic interaction related to a covalent character of atomic bonds (for A1~A7) or/and inlaid with face-centered-cubic aluminum (FCC-Al) nano-crystallites which were precipitated during the melt-spin quenching (for A1~A3). The GFA of the alloys ranks in the sequence of A4 > A5 > A6 > A7 > A2 > A3 > A1 which can be assessed by the supercooled liquid region ΔTm (=Tm-Tx), the reduced glass transition temperature Trg (=Tg/Tm), and other criteria such as γ′ = Tx/(Tg + Tm), δ′ = Tx/(Tm − Tg), β′ = TxTg/(Tm + Tx)2, and ω′ = Tm(Tm + Tx)/(Tx(Tm − Tx)); while the TS of the alloys lists in the series of A5 > A6 ~ A4 > A7 > A3 > A2 > A1 that can be evaluated by the first crystallization activation energy Ec, first crystallization activation enthalpy ΔH⁎, frequency factor Ko, fragility parameter m, and theoretical glass transition temperature Tg⁎. The hardness of the alloys A1~A7 accounts to 707, 809, 940, 863, 762, 809, and 715 MPa, respectively, attributing to a composite structure consisting of an amorphous matrix tessellated with SRO quasi-crystalline clusters or/and FCC-Al nano-crystallites. In addition, the alloys exhibit high corrosion resistance in the rate of 10−7–10−8 A/cm2 with a large passivation scope except that the alloy A7 presents a corrosion rate of 10−6 A/cm2 with an active anodic dissolution behavior. The results manifest the Al86Ce10TM4 alloys can be fabricated into a unique composite consisting of an amorphous matrix embedded with SRO quasi-crystalline or/and nano-crystalline phases which confers high mechanical hardness and corrosion resistance for potential engineering applications. Keywords: Amorphous alloys, Glass-forming ability, Thermal behavior, Al-Ce-TM, Electrochemistry
The neutron flux is a crucial factor for neutron scattering measurements, especially for compact sources. Among various neutron optics, grazing‐incidence focusing mirrors have been developed to give ...a significant increase in the neutron flux on a sample owing to their great potential for collecting neutrons in small‐angle neutron scattering (SANS) instruments. Focusing mirrors with a supermirror coating can be nested to collect a neutron beam with large divergence. Nested conical integrated assembly technology is employed to manufacture nested focusing mirrors. This study describes the design of ten‐shell nested fully annular quasi‐ellipsoidal focusing mirrors with an m = 3 Ni/Ti supermirror coating to produce enough neutrons on a sample under the premise of satisfying the specified minimum wavevector transfer Q. For fully annular focusing mirrors, the neutron current received by a sample from the entire annular focusing neutron beam is more relevant. A ray‐tracing method and current gain calculation are used to evaluate the performance of the designed mirrors. The ray‐tracing result shows that the ideal resolution of quasi‐ellipsoidal mirrors with four‐segment conical approximation is 1.354 mm. As the source radius decreases from 20 mm, the neutron current with the designed focusing mirrors can be enhanced by a factor of 13 to over 100 compared with that without focusing mirrors in the same detected area. The effective collecting area is 186 cm2 when the source radius is the optimal 15 mm. An 83‐fold current gain can be obtained for cold neutrons. The proposed mirrors can reach 90.7 and 87.3% of the maximum current of the corresponding optimal mirror structure when the source radii are 10 and 20 mm, respectively. The results demonstrate that the proposed mirrors are adaptable for instruments with changeable sources.
This study describes ten‐shell nested fully annular quasi‐ellipsoidal focusing mirrors with an m = 3 Ni/Ti supermirror coating for small‐angle neutron scattering. The proposed mirrors have been developed to gain enough neutrons on a sample for the specified minimum wavevector transfer Q and the results demonstrate adaptability for instruments with changeable sources.
The functionality and reliability of nanoscale multilayer devices and components are influenced by changes in stress and microstructure throughout fabrication, processing, and operation. NiV/Bsub.4C ...multilayers with a d-spacing of 3 nm were prepared by magnetron sputtering, and two groups of annealing experiments were performed. The stress, microstructure, and interface changes in NiV/Bsub.4C after annealing were investigated by grazing-incidence X-ray reflectometry (GIXR), grazing-incidence X-ray diffraction (GIXRD), X-ray diffuse scattering, and grazing-incidence small-angle X-ray scattering (GISAXS). The temperature dependence experiments revealed a gradual shift in the multilayer stress from compression to tension during annealing from 70 °C to 340 °C, with the stress approaching near-zero levels between 70 °C and 140 °C. The time-dependent experiments indicated that most of the stress changes occurred within the initial 10 min, which showed that prolonged annealing was unnecessary. Combining the X-ray diffraction and X-ray scattering measurements, it was found that the changes in the thickness, interface roughness, and lateral correlation length, primarily due to crystallization, drove the changes in stress and microstructure.
The functionality and reliability of nanoscale multilayer devices and components are influenced by changes in stress and microstructure throughout fabrication, processing, and operation. NiV/B4C ...multilayers with a d-spacing of 3 nm were prepared by magnetron sputtering, and two groups of annealing experiments were performed. The stress, microstructure, and interface changes in NiV/B4C after annealing were investigated by grazing-incidence X-ray reflectometry (GIXR), grazing-incidence X-ray diffraction (GIXRD), X-ray diffuse scattering, and grazing-incidence small-angle X-ray scattering (GISAXS). The temperature dependence experiments revealed a gradual shift in the multilayer stress from compression to tension during annealing from 70 °C to 340 °C, with the stress approaching near-zero levels between 70 °C and 140 °C. The time-dependent experiments indicated that most of the stress changes occurred within the initial 10 min, which showed that prolonged annealing was unnecessary. Combining the X-ray diffraction and X-ray scattering measurements, it was found that the changes in the thickness, interface roughness, and lateral correlation length, primarily due to crystallization, drove the changes in stress and microstructure.
Gas atomized Al88Ce8Fe4 alloy powders were ball-milled and investigated at charge ratiosof 5:1, 15:1 and 30:1 and milling speeds of 150 and 200 RPM, respectively. The morphology,microstructure and ...composition of the powders were examined by laser diffraction technique, SEM,EDS and XRD. The result indicates the evolution of the powders under milling experiences initiallycold welding, aggregating the powders into larger-sized disk-shaped particles; followed byfragmentation, forming smaller-sized equiaxed particles; and finally leading to a steady state, whereparticles morphology, composition and phases keep constantly unchanged. This procedure has beentestified as a general rule for milling at each of the charge ratios of 5:1, 15:1 and 30:1 and at millingspeeds of 150 and 200 RPM while milling at larger charge ratios or higher speeds drives faster toreach the steady state at which homogeneous, fine-sized glassy powders can be obtained.
碩士
嶺東科技大學
財務金融研究所
100
In this study, the three countries of the Asia-Pacific, Taiwan, Indonesia, Vietnam, the three countries, the stock market for the empirical, with fluctuations in the U.S. stock ...market share price and the market return pass to the impact analysis, to provide investors with the reference of the international portfolio. In addition to the GARCH model to investigate the compensation of fluctuations and information transmission fluctuations, due to the pass-through effect of the fluctuations between the U.S. and Asian stock markets are non-linear nature of, and thus followed a change bivariate GARCH - DCC model, do a more realistic description of the analysis were collected from October 11, 2006 December 2011 30, a total 1146 document the daily data information for analysis.
The empirical get the following conclusions: the United States and the Asia-Pacific shares did not pass the cointegration test showed no long-run equilibrium relationship. Granger causality test shows that the U.S. market
There is growing attention toward closed biological genomes in the environment and in health. To explore and reveal the intergroup differences among different samples or environments, it is crucial ...to discover biomarkers with statistical differences among groups. The application of Linear discriminant analysis Effect Size (LEfSe) can help find good biomarkers. Based on the original genome data, quality control, and quantification of different sequences based on taxa or genes are carried out. First, the Kruskal-Wallis rank test was used to distinguish between specific differences among statistical and biological groups. Then, the Wilcoxon rank test was performed between the two groups obtained in the previous step to assess whether the differences were consistent. Finally, a linear discriminant analysis (LDA) was conducted to evaluate the influence of biomarkers on significantly different groups based on LDA scores. To sum up, LEfSe provided the convenience for identifying genomic biomarkers that characterize statistical differences among biological groups.
Pasteurization is carried out in dairy industries to kill harmful bacteria present in raw milk. However, endospore-forming bacteria, such as Bacillus, cannot be completely eliminated by ...pasteurization. In this study, a total of 114 Bacillus strains were isolated from 133 pasteurized milk samples. Antibiotic susceptibility tests showed that the percentage of Bacillus with intrinsic resistance to ampicillin and penicillin were 80 and 86%, respectively. Meanwhile, some Bacillus isolates had acquired resistance, including trimethoprim-sulfamethoxazole resistance (10 isolates), clindamycin resistance (8 isolates), erythromycin resistance (2 isolates), and tetracycline resistance (1 isolate). To further locate these acquired resistance genes, the plasmids were investigated in these 16 Bacillus strains. The plasmid profile indicated that Bacillus cereus BA008, BA117, and BA119 harbored plasmids, respectively. Subsequently, the Illumina Novaseq PE150 was applied for the genomic and plasmid DNA sequencing. Notably, the gene tetL encoding tetracycline efflux protein was found to be located on plasmid pBC46-TL of B. cereus BA117. In vitro conjugative transfer indicated that pBC46-TL can be transferred into Bacillus invictae BA142, Bacillus safensis BA143, and Bacillus licheniformis BA130. The frequencies were of 1.5 × 10−7 to 1.7 × 10−5 transconjugants per donor cells. Therefore, Bacillus strains with acquired antibiotic resistance may represent a potential risk for the spread of antibiotic resistance between Bacillus and other clinical pathogens via horizontal gene transfer.
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