• Title/Summary/Keyword: metal nanoparticles

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Mössbauer Studied of Multiferroic Bi2/3La1/3FeO3 Nanoparticles (Multiferroic Bi2/3La1/3FeO3 나노입자의 Mössbauer 연구)

  • Lee, Seung-Wha
    • Journal of the Korean Magnetics Society
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    • v.16 no.1
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    • pp.28-33
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    • 2006
  • La substituted perovskite $BiFeO_3$ have been prepared by a sol-gel method. Magnetic and structural properties of the powders were characterized with Mossbauer spectroscopy, XRD, SEM, and TG-DTA. The crystal structure is found to be a rhombohedrally distorted perovskite structure with the lattice constant $\alpha=3.985{\AA}\;and\;\alpha=89.5^{\circ}.\;Bi_{2/3}La_{1/3}FeO_3$ powders that were annealed at and above $600^{\circ}C$ have a single-phase perovskite structure. However, powders annealed at $900^{\circ}C$ have a typical perovskite structure with small amount of $Bi_2O_3$ phase. The Neel temperature of $Bi_{2/3}La_{1/3}FeO_3$ is found to be $680\pm3K$. The isomer shift value at room temperature is found to be 0.27 mm/s relative to the Fe metal, which is consistent with high-spin $Fe^{3+}$ charge states. Debye temperature far$Bi_{2/3}La_{1/3}FeO_3$ is found to be $305\pm5K$. The average hyperfine field $H_{hf}(T)$ of the $Bi_{2/3}La_{1/3}FeO_3$, shows a temperature dependence of $[H_{hf}(T)-H_{hf}(0)]/H_{hf}(0)=-0.42(T/T_N)^{3/2}-0.13(T/T_N)^{5/2}$ for $T/T_N<0.7$ indicative of spin-wave excitation.

Preparation of Chitosan-Gold and Chitosan-Silver Nanodrug Carrier Using QDs (QDs를 이용한 키토산-골드와 키토산-실버 나노약물전달체 제조)

  • Lee, Yong-Choon;Kang, Ik-Joong
    • Korean Chemical Engineering Research
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    • v.54 no.2
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    • pp.200-205
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    • 2016
  • A drug transport carrier could be used for safe send of drugs to the affected region in a human body. The chitosan is adequate for the drug delivery carrier because of adaptable to living body. The gold, a metallic nanoparticles, tends to form a nano complex at rapidly when it combined with chitosan because of its negative charge. having energy from the other, outer gold nano-complex make heat due to its property to release the contained drugs to the target area. Silver could be also formed an useful biocompatible nano-composites with chitosan which should be used as an useful drug transfer carrier because its special ability to protect microbial contamination. Being one of the oxidized nano metals, $Fe_3O_4$ is nontoxic and has been used for its magnetic characteristics. In this study, the control of catalyst, reducing agent, and solvent amount. The chitosan-$Fe_3O_4$-gold & silver nanoshell have been changed to form about 100 nm size by ionic bond between the amine group, an end group of chitosan, and the metal. It was observed the change in order to seek for its optimum reaction condition as a drug transfer carrier.

Recent Research Trends in Antibacterial, Antifungal, and Antiviral Active Packaging (항균, 항진균 및 항바이러스 액티브 패키징의 최근 연구 동향)

  • Siyeon Park;Hani Ji;Jieun Choi;Seulgi Imm;Yoonjee Chang
    • KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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    • v.29 no.1
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    • pp.15-25
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    • 2023
  • Since the COVID-19 crisis, the use of disposable packaging materials and delivery services, which raise environmental and social issues with waste disposal, has significantly increased. Antimicrobial active packaging has emerged as a viable solution for extending the shelf-life of foods by minimizing microbial growth and decomposition. In this review article, we provide a comprehensive overview of current research trends in antimicrobial active film and coating published over the last five years. First, we introduced various polymer materials such as film and coating that are used in active packaging. Next, various types of antimicrobial (antibacterial, antifungal, and antiviral) packaging including essential oil, extracts, biological material, metal, and nanoparticles were introduced and their activities and mechanisms were discussed. Finally, the current challenges and prospects were discussed. Overall, this review provides insights into the recent advancements in antimicrobial active packaging research and highlights the potential of the technology to enhance food safety and quality.

Effect of Pt as a Promoter in Decomposition of CH4 to Hydrogen over Pt(1)-Fe(30)/MCM-41 Catalyst (Pt(1)-Fe(30)/MCM-41 촉매상에서 수소 제조를 위한 메탄의 분해 반응에서 조촉매 Pt의 효과)

  • Ho Joon Seo
    • Applied Chemistry for Engineering
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    • v.34 no.6
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    • pp.674-678
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    • 2023
  • The effect of Pt was investigated to the catalytic methane decomposition of CH4 to H2 over Pt(1)-Fe(30)/MCM-41 and Fe(30)/MCM-41 using a fixed bed flow reactor under atmosphere. The Fe2O3 and Pt crystal phase behavior of fresh Pt(1)-Fe(30)/MCM-41 were obtained via XRD analysis. SEM, EDS analysis, and mapping were performed to show the uniformed distribution of nano particles such as Fe, Pt, Si, O on the catalyst surface. XPS results showed O2-, O- species and metal ions such as Pt0, Pt2+, Pt4+, Ft0, Fe2+, Fe3+ etc. When 1 wt% of Pt was added to Fe(30)/MCM-41, automic percentage of Fe2p increased from 13.39% to 16.14%, and Pt4f was 1.51%. The yield of hydrogen over Pt(1)-Fe(30)/MCM-41 was 3.2 times higher than Fe(30)/MCM-41. The spillover effect of H2 from Pt to Fe increased the reduction of Fe particles and moderate interaction of Fe, Pt and MCM-41 increased the uniform dispersion of fine nanoparticles on the catalyst surface, and improved hydrogen yield.

Fabrication of Label-Free Biochips Based on Localized Surface Plasmon Resonance (LSPR) and Its Application to Biosensors (국소 표면 플라즈몬 공명 (LSPR) 기반 비표지 바이오칩 제작 및 바이오센서로의 응용)

  • Kim, Do-Kyun;Park, Tae-Jung;Lee, Sang-Yup
    • KSBB Journal
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    • v.24 no.1
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    • pp.1-8
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    • 2009
  • In the past decade, we have observed rapid advances in the development of biochips in many fields including medical and environmental monitoring. Biochip experiments involve immobilizing a ligand on a solid substrate surface, and monitoring its interaction with an analyte in a sample solution. Metal nanoparticles can display extinction bands on their surfaces. These charge density oscillations are simply known as the localized surface plasmon resonance (LSPR). The high sensitivity of LSPR has been utilized to design biochips for the label-free detection of biomolecular interactions with various ligands. LSPR-based optical biochips and biosensors are easy to fabricate, and the apparatus cost for the evaluation of optical characteristics is lower than that for the conventional surface plasmon resonance apparatus. Furthermore, the operation procedure has become more convenient as it does not require labeling procedure. In this paper, we review the recent advances in LSPR research and also describe the LSPR-based optical biosensor constructed with a core-shell dielectric nanoparticle biochip for its application to label-free biomolecular detections such as antigen-antibody interaction.

Study on Preparation of High Purity Lithium Hydroxide Powder with 2-step Precipitation Process Using Lithium Carbonate Recovered from Waste LIB Battery (폐리튬이차전지에서 회수한 탄산리튬으로부터 2-step 침전공정을 이용한 고순도 수산화리튬 분말 제조 연구)

  • Joo, Soyeong;Kang, Yubin;Shim, Hyun-Woo;Byun, Suk-Hyun;Kim, Yong Hwan;Lee, Chan-Gi;Kim, Dae-Guen
    • Resources Recycling
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    • v.28 no.5
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    • pp.60-67
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    • 2019
  • A valuable metal recovery from waste resources such as spent rechargeable secondary batteries is of critical issues because of a sharp increase in the amount of waste resources. In this context, it is necessary to research not only recycling waste lithium-ion batteries (LIBs), but also reusing valuable metals (e.g., Li, Co, Ni, Mn etc.) recovered from waste LIBs. In particular, the lithium hydroxide ($LiOH{\cdot}xH_2O$), which is of precursors that can be prepared by the recovery of Li in waste LIBs, can be reused as a catalyst, a carbon dioxide absorbent, and again as a precursor for cathode materials of LIB. However, most studies of recycling the waste LIBs have been focused on the preparation of lithium carbonate with a recovery of Li. Herein, we show the preparation of high purity lithium hydroxide powder along with the precipitation process, and the systematic study to find an optimum condition is also carried out. The lithium carbonate, which is recovered from waste LIBs, was used as starting materials for synthesis of lithium hydroxide. The optimum precipitation conditions for the preparation of LiOH were found as follows: based on stirring, reaction temperature $90^{\circ}C$, reaction time 3 hr, precursor ratio 1:1. To synthesize uniform and high purity lithium hydroxide, 2-step precipitation process was additionally performed, and consequently, high purity $LiOH{\cdot}xH_2O$ powder was obtained.