• Progress in Medical Physics
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• v.33 no.4
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• pp.114-120
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• 2022

Purpose: Particle beam therapy is advantageous over photon therapy. However, adequately delivering therapeutic doses to tumors near critical organs is difficult. Nanoparticle-aided radiation therapy can be used to alleviate this problem, wherein nanoparticles can passively accumulate at higher concentrations in the tumor tissue compared to the surrounding normal tissue. In this study, we investigate the dose enhancement effect due to gold nanoparticle (GNP) when Carbon-12, He-4, and proton beams are irradiated on GNP. Methods: First, monoenergetic Carbon-12 and He-4 ion beams of energy of 283.33 MeV/u and 150 MeV/u, respectively, and a proton beam of energy of 150 MeV were irradiated on a water phantom of dimensions 30 cm×30 cm×30 cm. Subsequently, the secondary-particle information generated near the Bragg peak was recorded in a phase-space (phsp) file. Second, the obtained phsp file was scaled down to a nanometer scale to irradiate GNP of diameter 50 nm located at the center of a 4 ㎛×4 ㎛×4 ㎛ water phantom. The dose enhancement ratio (DER) was calculated in intervals of 1 nm from the GNP surface. Results: The DER of GNP computed at 1 nm from the GNP surface was 4.70, 4.86, and 4.89 for Carbon-12, He-4, and proton beams, respectively; the DER decreased rapidly with increasing distance from the GNP surface. Conclusions: The results indicated that GNP can be used as radiosensitizers in particle beam therapy. Furthermore, the dose enhancement effect of the GNP absorbed by tumor cells can aid in delivering higher therapeutic doses.

• Korean Journal of Breeding Science
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• v.43 no.2
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• pp.145-153
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• 2011

To develop new varieties of rapeseed (Brassica napus L.), the seeds of three varieties 'Naehan', 'Tammi', and 'Halla' were treated with proton ion beams and gamma rays (0~2,000 Gy), and then the characteristics of the mutants induced were examined up to $M_5$ generation to select the lines with fixed useful traits. In $M_5$ generation, we had selected several lines that were highly fixed for some useful traits such as plant height, maturity and flower size; one line with both earlier maturity and shorter stem than wild type, one line with only earlier maturity, two lines with shorter stem, one line with large flower, and one line with chlorophyll mutation. Among them, NP600-1-1-198-2 (induced from variety 'Naehan' was treated with proton ion beams 600 Gy) was superior for its distinction from the original variety, uniformity and stability. The unique characteristics of NP600-1-1-198-2 were dark green leaves, green stem, yellow flower, and black seed coat. Its flowering date was April 14, eight days earlier than its original variety, while seed maturity date was June 16 (five days earlier) and plant height 105 cm (shorter by 10 cm). NP600-1-1-198-2 has 52 silique per panicle, 6.2 cm silique length, 23 seeds per silique, 4.2 g per 1000 seeds and 45.9% oil content. The seed oil contained 67.8% of oleic acid, 16.7% of linoleic acid and 7.3% of linolenic acid but no erucic acid.

• Applied Chemistry for Engineering
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• v.3 no.1
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• pp.100-110
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• 1992

Arylsulfonyl urea derivatives can be easily prepared in good yield by treating amines with arylsulfonyl carbamates in aqueous solution : 1) N-Arylsulfonyl-N'-aryl urea derivatives, 2) N-Arylsulfony-N'-alkyl urea derivatives, 3) N-Arylsulfonyl-N'- heterocyclic urea derivatives. The proposed reaction mechanisms for preparing arylsulfonyl ureas involve formation of an ion-pair conformation by initial acid-base reaction, then formation of a so-called tetrahedral intermediate by nucleophilic addition, followed by an acid-catalyzed elimination of an alkoxide ion and loss of a proton.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.97-97
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• 2016

Development of advanced Li-ion battery cells with high durability is critical for safe operation, especially in applications to electric vehicles and portable electronic devices. Understanding fundamental mechanism on the formation of a solid-electrolyte interphase (SEI) layer, which plays a substantial role in the electrochemical stability of the Li-ion battery, in a cathode was rarely reported unlike in an anode. Using first-principles density functional theory (DFT) calculations and ab-initio molecular dynamic (AIMD) simulations we demonstrate atomic-level process on the generation of the SEI layer at the interface of a carbonate-based electrolyte and a spinel $LiMn_2O_4$ cathode. To accomplish the object we calculate the energy band alignment between the work function of the cathode and frontier orbitals of the electrolyte. We figure out that a proton abstraction from the carbonate-based electrolyte is a critical step for the initiation of an SEI layer formation. Our results can provide a design concept for stable Li-ion batteries by optimizing electrolytes to form proper SEI layers.

• Bulletin of the Korean Chemical Society
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• v.12 no.3
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• pp.265-270
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• 1991

Theoretical calculations on the stabilization energies of framework atoms in hydrolyses Co(Ⅱ )-exchanged zeolite A were made using some potential energy functions and optimization program. The protons which are produced by hydrolysis of $[Co(H_2O)_n]^{2+}$ ion in large cavity showed a tendency to attack the framework oxygen atom O(1) preferentially, and the oxygen atom O(4) within OH- ion was coordinated at Al atom. The weakness of bonds between T(Si, Al) and oxygen by attack of proton and too large coordination number around small aluminum atom will make the framework of Co(Ⅱ)-exchanged zeolite A more unstable. The stabilization energy of $Co_4Na_4$-A framework (- 361.57 kcal/mol) was less than that of thermally stable zeolite A($Na_{12-}$A: - 419.68 kcal/mol) and greater than that of extremely unstable Ba(Ⅱ)-exchanged zeolite A($Ba_{6-}$A: - 324.01 kcal/mol). All the data of powder X-ray diffraction, infrared and Raman spectroscopy of Co(Ⅱ)-exchanged zeolite A showed the evidence of instability of its framework in agreement with the theoretical calculation. Three different groups of water molecules are found in hydrated Co(Ⅱ )-exchanged zeolite A; W(Ⅰ) group of water molecules having only hydrogen-bonds, W(Ⅱ) group water coordinated to $Na^+$ ion, ans W(Ⅲ) group water coordinated to Co(Ⅱ) ion. The averaged interaction energy of each water group shows the decreasing order of W(Ⅲ)>W(Ⅱ)>W(Ⅰ).

• Bulletin of the Korean Chemical Society
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• v.23 no.1
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• pp.107-111
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• 2002

The OSS2 (Oj？me-Shavitt-Singer 2)[L. Oj？me et al., J. Chem. Phys. 109, 5547 (1998)] model for the solvated proton in water is examined for $H_2O,\;H_3O^+,\;H_5O_2^+,\;H_7O_3^+,\;and\;H_9O_4^-$ by molecular dynamics (MD) simulations. The equilibrium molecular geometries and energies obtained from MD simulations at 5.0 and 298.15 K agree very well with the optimized calculations.

• Proceedings of the Membrane Society of Korea Conference
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• 2002.05a
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• pp.59-61
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• 2002

No Abstract, See Full-text

• Bulletin of the Korean Chemical Society
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• v.3 no.2
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• pp.66-70
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• 1982

The question of the bicyclohomoaromatic stabilization and destabilization is examined. The chemistry of bicyclo(3.2.1)octa-3,6-dienide anion has been studied on order to test these concepts. The bicyclooctadienide anion is shown to be stable delocalized ion which undergoes a facile proton-deuterium exchange reaction. The solvolysis of bicyclo(3.2.1)octa-3,6-dienyl p-nitrobenzoate is much slower than the monoene analog. We have made direct observation of the bicyclooctadienyl and octenyl cations by $^{19}F$-nmr spectroscopy, and were able to demonstrate that the bicyclooctadienyl cation was bishomoantiaromatic.

• Journal of Sensor Science and Technology
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• v.33 no.2
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• pp.63-69
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• 2024

A novel method for measuring hydrogen concentration is introduced, along with its working principle and a novel detection algorithm. This configuration requires no additional reference compartment for potentiometric electrochemical measurements; therefore, it is the most suitable for measuring dissolved hydrogen in the liquid phase. The sensor's electromotive force saturates at a certain point, depending on the hydrogen concentration during the heating process of the sensor operation. This dynamic temperature scanning method provides higher sensitivity than the constant temperature measurement method.

• Membrane Journal
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• v.26 no.6
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• pp.432-448
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• 2016

In the last decade, various types of energy harvesting and conversion systems based on ion exchange membranes (IEMs) have been developed for eco-friendly power generation and energy-grid systems. In these membrane-based energy systems, high ion selectivity and conductivity properties of IEMs are critical parameters to improve efficiency of the systems such as proton exchange membrane fuel cells, anion exchange membrane fuel cells, redox flow batteries, water electrodialysis for hydrogen production, and reverse electrodialysis. This article suggests variable approaches to overcome trade-off limitation of polymeric membrane ion transport properties by reviewing various types of composite ion-exchange membranes including novel inorganic-organic nanocomposite membrane, surface modified membranes, cross-linked and pore-filled membranes.