• Title/Summary/Keyword: template synthesis

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Synthesis and Characterization of Iron Incorporated MCM-41 (철 혼입 MCM-41 촉매의 제조 및 특성 연구)

  • Cho, Deug-Hee;Jin, Hangkyo
    • Applied Chemistry for Engineering
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    • v.19 no.2
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    • pp.242-248
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    • 2008
  • The iron incorporation method according to addition steps during the synthesis of iron incorporated MCM-41 was examined systematically. Iron addition during pH adjustment was more effective than the other addition steps which were addition to template agent solution or addition after mixing of template agent and sodium silicate solution. In case of iron addition after extraction of template agent from as-synthesized silica MCM-41, most of the iron was on the surface of pores not the frame work structure. Although the amount of iron addition was increased, there was a limit to the amount of iron incorporated into framework structure of MCM-41. The synthesized FeMCM-41 catalyst showed catalytic activities for propylene oxidation. Otherwise, there might be no attractive differences of catalytic activity among the addition steps of iron.

A Clue for Prebiotic Era: Cross-Catalytic Replication of an RNA Ligase Ribozyme

  • Kim Dong-Eun;Joyce Gerald F.
    • Proceedings of the Korean Society of Life Science Conference
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    • 2004.10a
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    • pp.22-26
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    • 2004
  • A self-replicating RNA ligase ribozyme was converted to a cross-catalytic format whereby two ribozymes direct each other's synthesis from a total of four component substrates. Each ribozyme binds two RNA substrates and catalyzes their ligation to form the opposing ribozyme. The two ribozymes are not perfectly complementary, as is the case for replicating nucleic acid genomes in biology. Rather, the ribozymes contain both template elements, which are complementary, and catalytic elements, which are identical. The specificity of the template interactions allows the cross-catalytic pathway to dominate over all other reaction pathways. In the presence of $2{\mu}M$ each of the corresponding substrates, one ribozyme catalyzes the synthesis of the second ribozyme with an initial rate of $6.8{\times}10^{-3}\;min^{-1}$, while the second ribozyme catalyzes the synthesis of the first with an initial rate of $2.9{\times}10^{-3}min{-1}$. As the concentration of the two ribozymes increases, the rate of formation of additional ribozyme molecules increases, consistent with the overall autocatalytic behavior of the reaction system. Here, I present results that possibly demonstrate a clue for a self-replicating molecule by showing an RNA ligase ribozyme, which is reminiscent of 'Prebiotic Era'.

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Influence of Surface Characteristics of Mesoporous Silica on Pb(II) and Cd(II) Adsorption Behavirous (Mesoporous silica의 표면특성이 Pb(II)와 Cd(II)의 흡착거동에 미치는 영향)

  • Lee, Ha-Young;Lee, Kamp-Du;Park, Sang-Won
    • Journal of Korean Society of Environmental Engineers
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    • v.30 no.6
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    • pp.673-679
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    • 2008
  • In this study, Mesoporous silica were prepared from hydrothermal synthesis using gel mixture of tetraethylorthosilcate (TEOS) as silica source and cetyltrimethylammonium bromide(CTMABr) as a template. In the optimum synthesis cause, molar ratio of template and silica changed. The surface and structure properties of Mesoporous silica were determined by XRD, SEM, and BET. N$_2$ adsorption isotherm characteristics, including the specific surface area(S$_{BET}$), total pore volume(V$_T$), and average pore diameter(D$_{BJH}$), were determined by BET. Also, the adsorption character of Pb(II) and Cd(II) ion on Mesoporous silica were measured using ICP. As a result, a SBET of 100$\sim$1,500 m$^2$/g was determined from the N$_2$ adsorption isotherm. Also, the average pore diameter of 2$\sim$4 nm. The adsorption of Pb ion and Cd ion on Mesoporous silica become different depending on the pH of solution. The adsorption amount of Mesoporus silica had higher than that of silicagel.

Synthesis of Hollow Mesoporous Carbon Nitride Spheres Using Polystyrene Spheres as Template (폴리스티렌 구형입자를 주형으로 이용한 할로우 메조포러스 질화탄소 구형입자의 합성)

  • Park, Sung Soo;Ha, Chang-Sik
    • Journal of Adhesion and Interface
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    • v.15 no.2
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    • pp.63-68
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    • 2014
  • Hollow mesoporous carbon nitride material with sphere shape was synthesized using polystyrene sphere as template and cyanamide as nitrogen and carbon atom sources via thermal treatment process. The process of the silica removal is not necessary because silica as template is not in use for the synthesis of hollow mesoporous carbon nitride material and any solvents are also not in use. The size of polystyrene spheres was about 170 nm. Hollow diameter and wall thickness were 82 nm and 13 nm, respectively, in hollow mesoporous carbon nitride sphere. Surface area, mesopore size and pore volume of hollow mesoporous carbon nitride material was $188m^2g^{-1}$, 3.8 nm and $0.35cm^3g^{-1}$, respectively. The wall in hollow sphere has graphitic structure. Hollow mesoporous carbon nitride material has potential applications in the area of fuel cell, catalysis, photocatalysis, electroemmision device, etc.

Controlled Synthesis of Spherical Polystyrene Beads and Their Template-Assisted Manual Assembly

  • Yoon, Seo Young;Park, Yi-Seul;Lee, Jin Seok
    • Bulletin of the Korean Chemical Society
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    • v.35 no.8
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    • pp.2281-2284
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    • 2014
  • Polystyrene beads (PS beads) with narrow size distribution were synthesized, and their diameter was controlled from 1.2 to $5{\mu}m$ by varying the injection rate of a styrene solution containing initiator and the concentration of reactant, such as initiator and capping material. The diameter of the PS beads increased with increasing in the injection rates and the initiator concentration or decreasing the capping material concentration. Then, we used the PS beads as building block, and organized them into a hexagonally close-packed monolayer on substrate with template-assisted manual assembly. We showed perfect hexagonally close-packed organization of the PS beads with various sizes in large-scale area. And we demonstrated the superiority of the dry manual assembly over the wet self-assembly in terms of simplicity, speed, perfect ordering, and large scale.

ENHANCED EXEMPLAR BASED INPAINTING USING PATCH RATIO

  • KIM, SANGYEON;MOON, NAMSIK;KANG, MYUNGJOO
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.22 no.2
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    • pp.91-100
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    • 2018
  • In this paper, we propose a new method for template matching, patch ratio, to inpaint unknown pixels. Before this paper, many inpainting methods used sum of squared differences(SSD) or sum of absolute differences(SAD) to calculate distance between patches and it was very useful for closest patches for the template that we want to fill in. However, those methods don't consider about geometric similarity and that causes unnatural inpainting results for human visuality. Patch ratio can cover the geometric problem and moreover computational cost is less than using SSD or SAD. It is guaranteed about finding the most similar patches by Cauchy-Schwarz inequality. For ignoring unnecessary process, we compare only selected candidates by priority calculations. Exeperimental results show that the proposed algorithm is more efficent than Criminisi's one.

Synthesis of Li4Ti5O12 Thin Film with Inverse Hemispheric Structure

  • Lee, Sung-Je;Jung, Kwang-Hee;Park, Bo-Gun;Kim, Ho-Gi;Park, Yong-Joon
    • Bulletin of the Korean Chemical Society
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    • v.31 no.2
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    • pp.360-364
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    • 2010
  • $Li_4Ti_5O_{12}$ thin film with inverse hemispheric structure was fabricated on a Pt/Ti/$SiO_2$/Si substrate by the sol-gel and dip coating method for use as an anode for 3-dimensional (3D) thin-film batteries. Polystyrene (PS) beads of 400 nm diameter were used to prepare the template for the inverse hemispheric structure. A coating solution prepared using precursor sources was dropped on the template-deposited substrates, which were then calcinated at $400^{\circ}C$. The template was removed by calcination, and the inverse hemispheric structure was successfully formed by an annealing process. The cyclic performance during high-rate charge/discharge processes of the $Li_4Ti_5O_{12}$ film with inverse hemispheric structure was superior to that of the flat $Li_4Ti_5O_{12}$ film.

New Cellular Neural Networks Template for Image Halftoning based on Bayesian Rough Sets

  • Elsayed Radwan;Basem Y. Alkazemi;Ahmed I. Sharaf
    • International Journal of Computer Science & Network Security
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    • v.23 no.4
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    • pp.85-94
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    • 2023
  • Image halftoning is a technique for varying grayscale images into two-tone binary images. Unfortunately, the static representation of an image-half toning, wherever each pixel intensity is combined by its local neighbors only, causes missing subjective problem. Also, the existing noise causes an instability criterion. In this paper an image half-toning is represented as a dynamical system for recognizing the global representation. Also, noise is reduced based on a probabilistic model. Since image half-toning is considered as 2-D matrix with a full connected pass, this structure is recognized by the dynamical system of Cellular Neural Networks (CNNs) which is defined by its template. Bayesian Rough Sets is used in exploiting the ideal CNNs construction that synthesis its dynamic. Also, Bayesian rough sets contribute to enhance the quality of the halftone image by removing noise and discovering the effective parameters in the CNNs template. The novelty of this method lies in finding a probabilistic based technique to discover the term of CNNs template and define new learning rules for CNNs internal work. A numerical experiment is conducted on image half-toning corrupted by Gaussian noise.