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排序方式: 共有444条查询结果,搜索用时 203 毫秒
1.
Kye-Hwan Byun Shin Young Park Dong Un Lee Hyang Sook Chun 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2020,37(3):507-518
ABSTRACTThis study investigated the antifungal effect of ultraviolet-C (UV-C) against Aspergillus flavus and Aspergillus parasiticus on roasted coffee beans. Also, any changes in the quality of the roasted coffee beans were measured after UV-C irradiation. As UV-C irradiation time increased (0–2 h), the number of surviving A. flavus and A. parasiticus spores significantly (P < .05) decreased. The reduction values of A. flavus in round part, crack part, and whole roasted coffee beans were 2.16, 0.71, and 1.58 log10 CFU g?1, respectively, and the reduction values of A. parasiticus in round part, crack part, and whole roasted coffee beans were 1.03, 0.37, and 0.72 log10 CFU g?1, respectively, after 2 h of UV-C irradiation. Field emission scanning electron microscopy showed that the morphology of A. flavus and A. parasiticus spores included expanded wrinkles that were deformed by UV-C irradiation. The Hunter colours were significantly reduced (P < .05). There was no significant change (P > .05) in moisture content, but the pH was significantly decreased (P < .05). Most of the sensory parameters did not change, but there was a significant difference (P < .05) in flavour. Based on this study, 2 h of UV-C irradiation was effective in reducing 90% of A. flavus, but it was not effective against A. parasiticus present on roasted coffee beans. Also, Hunter colour, pH, and sensory parameters (flavour) were changed by UV-C irradiation. 相似文献
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Qayoom Mubashir Shah Khurshed Ahmad Pandit Altaf Hussain Firdous Arfat Dar Ghulam Nabi 《Journal of Electroceramics》2020,45(1):7-14
Journal of Electroceramics - Hematite (α-Fe2O3) nanoparticles were synthesized by modified solution combustion method using a mixture of hexamethylenetetramine (HMTA) and glycine fuels at fuel... 相似文献
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Volatile Organic Compound from Pulicaria gnaphalodes and the Antibacterial and Antifungal Properties of Its Essential Oil and Aqueous,Ethanolic and Methanolic Extracts 下载免费PDF全文
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AbstractModel order reduction is a common practice to reduce large order systems so that their simulation and control become easy. Nonlinearity aware trajectory piecewise linear is a variation of trajectory piecewise linearization technique of order reduction that is used to reduce nonlinear systems. With this scheme, the reduced approximation of the system is generated by weighted sum of the linearized and reduced sub-models obtained at certain linearization points on the system trajectory. This scheme uses dynamically inspired weight assignment that makes the approximation nonlinearity aware. Just as weight assignment, the process of linearization points selection is also important for generating faithful approximations. This article uses a global maximum error controller based linearization points selection scheme according to which a state is chosen as a linearization point if the error between a current reduced model and the full order nonlinear system reaches a maximum value. A combination that not only selects linearization points based on an error controller but also assigns dynamic inspired weights is shown in this article. The proposed scheme generates approximations with higher accuracies. This is demonstrated by applying the proposed method to some benchmark nonlinear circuits including RC ladder network and inverter chain circuit and comparing the results with the conventional schemes. 相似文献
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Jong Un Lee Sang-Hoon Kim Wan-Kuen Jo Won-Hwa Hong Woong Kim Jun Ho Bae Sung Hyuk Park 《Metals and Materials International》2018,24(4):730-737
Grain-refined AZ92 (GR-AZ92) alloy with superior tensile properties is developed by adding 1 wt% Zn and a very small amount of SiC (0.17 wt%) to commercial AZ91 alloy for enhancing the solid-solution strengthening effect and refining the crystal grains, respectively. The homogenized GR-AZ92 alloy with an average grain size of 91 μm exhibits a tensile yield strength (TYS) of 125 MPa, ultimate tensile strength (UTS) of 281 MPa, and elongation of 12.1%, which are significantly higher than those of AZ91 alloy with a grain size of 420 μm (TYS of 94 MPa, UTS of 192 MPa, and elongation of 7.0%). The peak-aging time of GR-AZ92 alloy (8 h) is significantly shorter than that of AZ91 alloy (32 h) owing to a larger amount of grain boundaries in the former, which serve as nucleation sites of Mg17Al12 precipitates. A short-aging treatment for less than 1 h of the GR-AZ92 alloy causes an effective improvement in its strength without a significant reduction in its ductility. The 30-min-aged GR-AZ92 alloy has an excellent combination of strength and ductility, with a TYS of 142 MPa, UTS of 304 MPa, and elongation of 8.0%. 相似文献
9.
Ukjae Lee Yun Sung Woo Yoojoong Han Humberto R. Gutiérrez Un Jeong Kim Hyungbin Son 《Advanced materials (Deerfield Beach, Fla.)》2020,32(38):2002854
Post-growth graphene transfer to a variety of host substrates for circuitry fabrication has been among the most popular subjects since its successful development via chemical vapor deposition in the past decade. Fast and reliable evaluation tools for its morphological characteristics are essential for the development of defect-free transfer protocols. The implementation of conventional techniques, such as Raman spectroscopy, atomic force microscopy (AFM), and transmission electron microscopy in production quality control at an industrial scale is difficult because they are limited to local areas, are time consuming, and their operation is complex. However, through a one-shot measurement within a few seconds, phase-shifting interferometry (PSI) successfully scans ≈1 mm2 of transferred graphene with a vertical resolution of ≈0.1 nm. This provides crucial morphological information, such as the surface roughness derived from polymer residues, the thickness of the graphene, and its adhesive strength with respect to the target substrates. Graphene samples transferred via four different methods are evaluated using PSI, Raman spectroscopy, and AFM. Although the thickness of the nanomaterials measured by PSI can be highly sensitive to their refractive indices, PSI is successfully demonstrated to be a powerful tool for investigating the morphological characteristics of the transferred graphene for industrial and research purposes. 相似文献
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Chidinma Judith Oluigbo Nabi Ullah Meng Xie Chukwuma Christian Okoye Bashir Adegbemiga Yusuf Waleed Yaseen Jagadeeh Kumar Alagarasan Kanagaraj Rajalakshmi Yuanguo Xu Jimin Xie 《国际能源研究杂志》2020,44(11):9157-9165
Cheap production of hydrogen (H2) from eco-friendly routes is preeminent for solving future energy challenges. This study explores the hydrogen evolution reaction (HER) activity of nickel (Ni) nanoparticles and nitrogen doped carbon nanotubes (NiNCNTs), which are fabricated by a cheap and one-step pyrolysis method. The most active catalyst synthesized at 800°C exhibits an overpotential of 0.244 V to reach a current density of 10 mA cm−2, Tafel slope of 93.3 mV dec−1 and a satisfactory 10 hours stability. Low resistance and large ECSA value of the sample also favor the competent response for HER in alkaline media. The robust HER activity of the catalyst is as a result of the nickel nanoparticles which are the active spots of reaction; while the presence of well-developed nitrogen containing carbon nanotubes with large content of pyridinic and graphitic nitrogen may provide high-electron density and feasible routes for its transportation to deliver an outstanding HER performance. 相似文献