• 한국자기학회지
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• 제6권4호
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• pp.225-234
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• 1996

자기 기록용 전구체에 적합한 침상형 $\alpha-Fe_{2}O_{3}$ 입자를 수열반응법에 의해 수용액 중에서 비정질 수산화제이철로부터 직접 제조하였다. Ellipsoidal 또는 rectangular 형상의 $\alpha-Fe_{2}O_{3}$ 입자는 염기도 10.75~11.75 범위에서 생성되었다. 구연산 농도가 증가함에 따라 침상 입자의 길이와 침상비는 점차 감소하였으며, 구연산 농도 $1.5{\times}10^{-4}\;mol$ 이상 일때는 침상형 $\alpha-Fe_{2}O_{3}$ 입자로의 결정화가 저해되었다. 수열 반응 온도 $140^{\circ}C$에서 가장 침상성이 우수한 $\alpha-Fe_{2}O_{3}$ 입자가 제조되었으며, $220^{\circ}C$ 이상에서는 침상형 입자의 생성을 기대할 수 없었다.

• Nuclear Engineering and Technology
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• 제49권4호
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• pp.881-885
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• 2017

This work presents a new technique for discriminating between alpha particles of different energy levels. In a first study, two groups of alpha particles emitted from radium-226 and americium-241 sources were successfully separated using a CR-39 microfilm of appropriate thickness. This thickness was adjusted by chemical etching before and after irradiation so that lower-energy particles were stopped within the detector, while higher-energy particles were revealed on the back side of the detector. The number of tracks on the front side of the microfilm represented all alpha particles incident on that side from the two sources. However, the number of tracks on the back side of the microfilm represented only the long-range alpha particles of higher energy that arrived at that side. Therefore, by subtracting the number of tracks on the back side from the number of tracks on the front side, one could easily determine the number of tracks for the short-range alpha particles of lower energy that remained embedded in the microfilm. Discrimination of the two energy levels is thus achieved in a simple, fast, and reliable process.

• 한국결정성장학회지
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• 제28권2호
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• pp.69-73
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• 2018

$100^{\circ}C$에서 0.03 M $FeCl_3$ 용액을 이용하여 수열법으로 제조한 80~90 nm의 ${\alpha}-Fe_2O_3$ 나노크기 입자의 결정 성장이 유연 frit 및 무연 frit에서 조사되었다. 두 종류의 frit 내에 있는 나노사이즈 ${\alpha}-Fe_2O_3$ 입자를 $800^{\circ}C$로 가열하였고 frit 내의 ${\alpha}-Fe_2O_3$ 입자의 평균 입경이 각각 200~210 nm과 150~160로 증가했다. 또한 ${\alpha}-Fe_2O_3$의 응집과 소결로 인해 결정 성장이 촉진된다는 사실도 확인되었다. 직경이 100 nm를 초과하는 큰 입자의 형성 비는 무연 frit에서 54 %, Pb가 함유된 유연 frit에서는 85 %였다. $800^{\circ}C$에서 frits 내에 있는 ${\alpha}-Fe_2O_3$ 입자를 가열함으로써, 평균 직경 7~9 nm의 기공이 ${\alpha}-Fe_2O_3$ 입자 내에 형성되었다. 이들 기공은 원래의 ${\alpha}-Fe_2O_3$ 입자 내의 한층 더 미세한 기공들로 구성된 다공성 구조에서 유래되었고, 소결 중 이들 미세 기공들은 입자에 갇혀있는 상태에서 서로 결합하여 7~9 nm의 기공 크기로 성장하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 고액공존금속의 성형기술 심포지엄
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• pp.183-195
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• 1997

The micorstructural characteristics, particularly $\alpha$-halo formation, in semi-solid state processed hypereutectic Al-Si alloy was investigated. The microstructural changes during reheating of wedge type mold cast ingot, hot-rolled sheet, and Si particulate reinforced Al composite was compared with those occurred during stirring of semi-solid state hypereutectic alloy. In the case of semi-solid state reheating of wedge type ingot and hot-rolled sheet, fine particles of Si as well as $\alpha$-halo formed after heat treatment. Although there seemed to be no coarsening with variations of holding time, the region of $\alpha$-halo decreased due to homogenization. Nucleation and recrystallization was accelerated with the addition of alloying elements during hot rolling resulting in primary Si particle size decrease and $\alpha$-halo formation. In the case of extruded specimens, very little morphological change of reinforcing Si particles was observed. Almost no $\alpha$-halo formed during reheating because of the oxide film formed on the reinforcing Si particles which acted as a diffusion barrier between the matrix and the primary Si particles.

• 한국세라믹학회지
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• 제24권3호
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• pp.215-222
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• 1987

${\alpha}$-Ferric Hydrous Oxide and ${\alpha}$-Ferric Oxide were obtained as following processes that Ferric Nitrate solution was adjusted to pH 6-8 with Ammonium Hydroxide, refluxed the Iron precipitate for 1 hr. at 80$^{\circ}C$, washed it with water and Methanol (95%), dried it to obtain ${\alpha}$-Ferric Hydrous Oxide at 60$^{\circ}C$, and then heated in atmosphere to prepare ${\alpha}$-Ferric Oxide for 1 hr. at 450$^{\circ}C$. Mica particles cleaned with ultrasonicator (45KHz) in water were mixed with Ferric Nitrate solution and treated it to adsorb ${\alpha}$-Ferric Oxide on the surface of mica particles by using the abovementioned processes, but the heated temperature was at 500$^{\circ}C$. The maximum wavelength of reflected light on the surface of mica-${\alpha}$-Ferric Oxide (50%) was appeared at 546nm but -Ferric Oxide free mica only was at 436 nm. The maximum wavelength was shifted to longer when the weight ratios of ${\alpha}$-Ferric Oxide to mica was changed from 1% to 50%.

• 대한방사선기술학회지:방사선기술과학
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• 제46권5호
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• pp.379-394
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• 2023

Targeted Alpha Therapy (TAT) is a new method of cancer treatment that protects normal tissues while selectively killing tumor cells using high cytotoxicity and short range of alpha particles, and target alpha therapy is a highly specific and effective cancer treatment strategy, and its potential has been proven through many clinical and experimental studies. This treatment method accurately delivers alpha particles by selecting specific molecules present in cancer tissue, which has an effective destruction and tumor suppression effect on cancer cells, and one of the main advantages of target alpha treatment is the physical properties of alpha particles. Alpha particles have a very high energy and short effective distance, interacting with target molecules in cancer tissues and having a fatal effect on cancer cells, which is known to cause DNA damage and cell death in cancer cells. TAT has shown positive results in preclinical and clinical studies for various types of cancers, especially those that resist or are unresponsive to existing treatments, but there are several challenges and limitations to overcome for successful clinical transition and application. These include the provision and production of suitable alpha radioisotopes, optimization of target vectors and delivery formulations, understanding and regulation of radiological effects, accurate dosage calculation and toxicity assessment. Future research should focus on developing new or improved isotopes, target vectors, transfer formulations, radiobiological models, combination strategies, imaging techniques, etc. for TAT. In addition, TAT has the potential to improve the quality of life and survival of cancer patients due to the possibility of a new treatment for overcoming cancer, and to this end, prospective research on more carcinomas and more diverse patient groups is needed.

• 한국의류학회지
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• 제25권8호
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• pp.1465-1474
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• 2001

The dispersion stability of particles and the adsorption of surfactant were examined as a fundamental environment to adhesion of particulate soil to fabric. The adsorption of surfactant on the PEF fabrics decreased with the addition of electrolytes and decreased with increasing the ionic strengths showed similar tendency to PET fabric. And the dispersion force of $\alpha$-Fe$_2$O$_3$particles decreased with the addition of electrolyte. The adhesion of particulate soil to fabric, increased with decreasing the adsorption of surfactant the correlation between the two was high at low ionic strength. The correlation between the adsorption of surfactants on $\alpha$-Fe$_2$O$_3$ particles and the adhesion of particles to fabric was smaller as shown in the correlation between the adsorption of surfactants on fiber substrate and the adhesion of particles on fabric. However, the correlation between the adhesion of particles to fabric and the stability of particle dispersion was relatively more significant.

• 한국의류학회지
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• 제17권3호
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• pp.380-390
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• 1993

Effect of interfacial electrical conditions on adhesion of ${\alpha}-Fe_2O_3$ particles to PET fabric and the removal of ${\alpha}-Fe_2O_3$ particles from PET fabric, were investigated as functions of pH, electrolyte and ionic strength. The ${\zeta}$ potential of PET fiber and ${\alpha}-Fe_2O_3$ particles in the electrolyte solution were measured by streaming potential and microelectrophoresis methods respectively. The potential energy of interaction between ${\alpha}-Fe_2O_3$ particles and PET fabric were calculated by using the heterocoagulation theory for a sphere-plate model. The negative ${\zeta}$ potential of ${\alpha}-Fe_2O_3$ particle and PET fiber increased with pH, and then decreased certain pH and isoelectric points of ${\alpha}-Fe_2O_3$ particles and PET fiber were pH 6.5 and pH 3.5, respectively. The negative ${\zeta}$ potential of ${\alpha}-Fe_2O_3$ particle and PET fiber affected by electrolytes, were relatively high with polyanion electrolytes in solutions and were low with neutral salts. However, at surfactant solution, ${\zeta}$ potential was levelled off. The influence of the ionic strength on the ${\zeta}$ potential of ${\alpha}-Fe_2O_3$ particle was small but the negative ${\zeta}$ potential of PET fiber increased with the ionic strength. In the presence of anionic surfactant, the ${\zeta}$ potential of ${\alpha}-Fe_2O_3$ particle and PET fiber increased regardless of solution conditions. The interaction energy between ${\alpha}-Fe_2O_3$ particle and PET fabric increased with pH. The interaction energy was relatively high with polyanion electrolytes in solution, and the influence of ionic strength on the interaction energy was small, and the effective thickness of electrical double layer increased with decreasing the ionic strength.

• 한국의류학회지
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• 제22권8호
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• pp.1132-1140
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• 1998

The adhesion and removal of $\alpha$-Fe2O3 particles on the from PET fabric in NPE solution with different ionic strength were discussed in terms of interaction of surface charge of particle and substrate. The adhesion of $\alpha$-Fe2O3 particles to PET fabric and its removal from PET fabric were carried out by using water bath shaker and Terg-O-Tometer under various solution conditions. The ζ potential of PET fiber and $\alpha$-Fe2O3 particles in the detergent solution were measured by steaming potential and microelectrophoresis methods, respectively. The adhesion and removal amount of $\alpha$-Fe2O3 particles on the from PET fabric increased with increasing time of adhesion and removal, and the rates of adhesion and removal were high at the initial stage of adhesion and removal, and then the rates decreased with passing time. The adhesion and removal amount of $\alpha$-Fe2O3 particles on and from PET fabric increased with increasing pH of solution regardless ionic strength. The tendencies and degree of adhesion and removal were very similar regardless interaction of surface charge of particle and fiber. Therefore, in the presence of a surfactant and electrolyte, the influence of interaction of surface charge of particle and substrate on the detergency of particulate soil was small.

• 한국인쇄학회지
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• 제20권2호
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• pp.95-106
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• 2002

The effect of various precipitants on the sizes and the shapes was investigated using a scanning electron microscopes when the ${\alpha}$-FeOOH particles was possible in a selection of an appropriate precipitants after due considerations of the shape and the growth of particles.