• Korean Journal of Radiology
• /
• v.24 no.11
• /
• pp.1131-1141
• /
• 2023

Objective: Cortical iron deposition has recently been shown to occur in Alzheimer's disease (AD). In this study, we aimed to evaluate how cortical gray matter iron, measured using quantitative susceptibility mapping (QSM), differs in the clinical cognitive impairment spectrum. Materials and Methods: This retrospective study evaluated 73 participants (mean age ± standard deviation, 66.7 ± 7.6 years; 52 females and 21 males) with normal cognition (NC), 158 patients with mild cognitive impairment (MCI), and 48 patients with AD dementia. The participants underwent brain magnetic resonance imaging using a three-dimensional multi-dynamic multi-echo sequence on a 3-T scanner. We employed a deep neural network (QSMnet+) and used automatic segmentation software based on FreeSurfer v6.0 to extract anatomical labels and volumes of interest in the cortex. We used analysis of covariance to investigate the differences in susceptibility among the clinical diagnostic groups in each brain region. Multivariable linear regression analysis was performed to study the association between susceptibility values and cognitive scores including the Mini-Mental State Examination (MMSE). Results: Among the three groups, the frontal (P < 0.001), temporal (P = 0.004), parietal (P = 0.001), occipital (P < 0.001), and cingulate cortices (P < 0.001) showed a higher mean susceptibility in patients with MCI and AD than in NC subjects. In the combined MCI and AD group, the mean susceptibility in the cingulate cortex (β = -216.21, P = 0.019) and insular cortex (β = -276.65, P = 0.001) were significant independent predictors of MMSE scores after correcting for age, sex, education, regional volume, and APOE4 carrier status. Conclusion: Iron deposition in the cortex, as measured by QSMnet+, was higher in patients with AD and MCI than in NC participants. Iron deposition in the cingulate and insular cortices may be an early imaging marker of cognitive impairment related neurodegeneration.

• Journal of Microbiology and Biotechnology
• /
• v.21 no.1
• /
• pp.28-36
• /
• 2011

Diblock copolymers composed of poly(${\varepsilon}$-caprolactone) (PCL) and poly(N,N-dimethylamino-2-ethyl methacrylate) (PDMAEMA), or methoxy polyethylene glycol(PEG), were synthesized via a combination of ring-opening polymerization and atom-transfer radical polymerization in order to prepare polymeric nanoparticles as an antifungal drug carrier. Amphotericin B (AmB), a natural antibiotic, was incorporated into the polymeric nanoparticles. The physical properties of AmB-incorporated polymeric nanoparticles with PCL-b-PDMAEMA and PCL-b-PEG were studied in relation to morphology and particle size. In the aggregation state study, AmB-incorporated PCL-b- PDMAEMA nanoparticles exhibited a monomeric state pattern of free AmB, whereas AmB-incorporated PCL-b- PEG nanoparticles displayed an aggregated pattern. In in vitro hemolysis tests with human red blood cells, AmBincorporated PCL-b-PDMAEMA nanoparticles were seen to be 10 times less cytotoxic than free AmB (5 ${\mu}g$/ml). In addition, an improved antifungal activity of AmBincorporated polymeric nanoparticles was observed through antifungal activity tests using Candida albicans, whereas polymeric nanoparticles themselves were seen not to affect activity. Finally, in vitro AmB release studies were conducted, proving the potential of AmB-incorporated PCL-b-PDMAEMA nanoparticles as a new formulation candidate for AmB.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.7 no.1
• /
• pp.31-63
• /
• 1969

A series of experiment was carried out to study on the production of disease-free seed potatoes at the Alpine Experiment Station from 1960 to 1968, which initiated a study of comparison on degeneration of plain warm region and high altitude products and the effect of latent potato virus X (PVX) and potato leaf roll virus(PLRV) on degeneration. Particular observations were made on some aspect of the nature of potato virus disease and its control such as concentrations of PVX, range of host plants, physical properties such as concentrations of PYX, range of host plants, physical properties and carrying effect of insects, by investigating 9 different areas of the main potato producing regions (Kimhae, Taegu, Choongju, Taejoen, Suwon, Kwangju, Chonju, Cheju and Chinju). Highly purified anti-serum was separated and tested for control of the virus disease and also various method of prevention and control of PLRV were observed, using cultivation of sprouted seed tubers, early harvesting method, and systemic chemicals. The results obtained are summarized as follows; 1. Potato yield in the plain region decreased by 32.8~66.3% in the first year cultivation of seed potatoes from colder region, and the rate of virus infection was 92.9 to 95.4%. 2. Plants of three families including, 20 species were susceptible to the PVX, and among the plants Salvia officinalis of a habits only was the carrier while the symptom of Digitalis purpurea of Screphulariaceae was masked. Necrosis and ring spot was occurred in most pJants of the Solanaceae and ring spot symptom also was observed in Nicotiana tabacum L. var. White Burley and in N. glutinosa. 3. The 8$C_2$ strain of virus had the following physical properties; thermal inactivation point, 68-$72^{\circ}C$ : dilution inactivation point, above 1, 000, 000 dilution: ageing in vitro, 240-360 days: and ageing in dry plant tissue, 30 days. 4. Myzus persicae and Oxya spp. did not transmit the 8$C_2$ strain of potato virus. 5. Virus was purified through the ammonium sulphate isolating method, and higher titer value, 1/2048 was obtained through anti-serum test. 6. Inhibition Chenopodiacae on the virus infection of potato was remarkable, and inhibition of local lesion host also was observed. 7, By earlier planting of sprouted seed tubers, growth period could be prolonged by 10 to 12 days. 8. Earlier harvest decreased much the rate of virus infection of seed potatoes. 9. According to the results of aphid control trial using systemic soil insecticides at Kangnung and Taekwanlyung, PSP 204, Disyston and Thimet was effective to aphid control. In particular, control effect of twice treatments of PSP 204 was great. 10. Treatmental effect of those chemicals lasted about 60-70 days. However, single foliar application of emulsified chemicals was not effective to potato virus control. 11. The effect of PSP 204, Disyston, and Thimet on the control of potato leaf roll virus was great, particularly in the case of two treatments of PSP 204, at Kangnung as well as at Taekwanlyung. Higher negative correlationship between the control effect of potato leaf roll virus and potato yield was observed showing the value r=-0.85 at Kangnung, and r=-0.87 at Taekwanlyung. 12. Differences in the control effects among PSP 204, Disyston, and Thimet was not noticed.

• Applied Chemistry for Engineering
• /
• v.28 no.4
• /
• pp.404-409
• /
• 2017

Natural polymer chitosan has been widely applied to medical fields due to its biochemical activities such as anticancer, antibacterial and lowering cholesterol in addition to biocompatibility and biodegradability. Currently, researches are being actively conducted to develop various drug-encapsulated chitosan nanoparticles for curing different diseases by applying chitosan to a drug delivery system. The free amine ($-NH_2$) group present in chitosan can bind to various hydrophobic groups by physical and chemical modification and the chitosan with hydrophobic groups can form shell-core nanoparticles by self-assembly when dispersed in water. In addition, an insoluble drug can increase the solubility against water when it was encapsulated in the core of chitosan nanoparticles. Also, the therapy effect can be maximized by minimizing side effects of drugs such as proteins, anticancer drugs and vaccines when they were encapsulated in the core of chitosan nanoparticles. Moreover, it is possible to control the particle size and release rate according to the hydrophobic group introduced to chitosan, so that it can be applied to a wide range of medical fields. The purpose of this review is to discuss the preparation and property of chitosan nanoparticles modified with various hydrophobic groups, and the application to drug delivery systems according to their property.

• Journal of Distribution Science
• /
• v.12 no.10
• /
• pp.123-128
• /
• 2014

Purpose - The purpose of the study is to reexamine the price fairness as practiced by low cost airlines, as a consumer has to experience such inconveniences as inferior airport transportation, extra fees on in-flight meals, and non-negotiable seats, and consumers evaluate such experiences keeping in mind their total costs. This evaluation includes price fairness and allows a reasonable and overall consideration of factors of low cost airlines. It tries to set up a measurement of the indicators consumers' perceptions of price fairness academically as it adapts price fairness to airline services which are renowned for price volatility. Research design, data, and methodology - The research proposes an alternative pricing strategy for the long term profit of low cost airlines after going over conflicts between the traditional theory of consumers' price perception mechanism and flexible fair policy of low cost airlines. It was meaningful when it relates to the early stage of the business, while it enhances the risks relating to the long term survival of low cost airlines. In addition, it is significant as it highlights the negative influences on consumers' perceptions of price fairness, as low cost airlines run on extremely low cost perspectives. Results - The results of the research provide insight into four perspectives, as consumers' perceptions of price fairness are influenced by the frequency and range of price changes and services. The first perspective is that it would lead to positive price evaluation when a low cost airline cuts prices frequently with little changes than one big change. It also would lead to the same result when it comes to necessary services. The second perspective is that one big increase of price would rather undermine the negative aspects of price changes than those of several smaller ones. The third perspective is that additional services would be good to consumers' perceptions of price fairness as compared to discount benefits with respect to the cost. Finally, a low cost airline should consider that consumers will change airlines or defer their flight schedule if the flight fares increase beyond their limits. Conclusions - Low cost airlines should reconsider their pricing policies for services that were provided free earlier. A consumer would not like discount benefits when made to pay for services that were, for long, free of charge. If a low cost airline can provide services with no charge, it should improve volumes if the costs are standardized and, moreover, should consider the charging fees. Alternatively, a consumer can choose between services and fair discount. Low cost airlines are implementing sales promotion strategies, as the competition is more intense than it used to be. In these days, they should regard services over sales promotion, as consumers may prefer to spend money on good premium services. Some differentiation in services could create a good market position for the airlines and, hence, good financial performance.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.12 no.4
• /
• pp.202-209
• /
• 2002

The stochiometric mix of evaporating materials for the $CuInSe_2$single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, $CuInSe_2$compound crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $620^{\circ}C$ and $410^{\circ}C$, respectively. The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $CuInSe_2$single crystal thin films measured from Hall effect by van der Pauw method. From the photocurrent spectrum by illumination of perpendicular light on the c-axis of the $CuInSe_2$single crystal thin film, we have found that the values of spin orbit splitting $\Delta$So and the crystal field splitting $\Delta$Cr. From the photoluminescence measurement on $CuInSe_2$single crystal thin film, we observed free exciton ($E_x$) existing only high quality crystal and neutral bound exciton ($A^{\circ}$, X) having very strong peak intensity. Then, the full-width-at-half-maximum (FWHM) and binding energy of neutral donor bound exciton were 7 meV and 5.9 meV, respectivity. By haynes rule, an activation energy of impurity was 59 meV.

• Korean Journal of Crystallography
• /
• v.12 no.3
• /
• pp.127-136
• /
• 2001

A stoichiometric mixture of evaporating materials for ZnGa₂Se₄single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, ZnGa₂Se₄mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperatures were 610℃ and 450℃, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of ZnGa₂Se₄single crystal thin films measured from Hall effect by von der Pauw method are 9.63×10/sup 17/㎤ and 296 ㎠/V·s at 293 K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c-axis of the ZnGa₂Se₄single crystal thin film, we have found that the values of spin orbit splitting △so and the crystal field splitting Δcr were 251.9meV and 183.2 meV at 10 K, respectively. From the photoluminescence measurement on th ZnGa₂Se₄single crystal thin film, we observed free excition (Ex) existing only high quality crystal and neutral bound exiciton (A°, X) having very strong peak intensity. Then, the full-width-at-half-maximum (FWHM) and binding energy of neutral acceptor bound excition were 11 meV and 24.4 meV, respectivity. By Haynes rule, an activation energy of impurity was 122 meV.

• Journal of Sensor Science and Technology
• /
• v.10 no.6
• /
• pp.328-337
• /
• 2001

The stochiometric mix of evaporating materials for the $CdGa_2Se_4$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, $CdGa_2Se_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $630^{\circ}C$ and $420^{\circ}C$, respectively. The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $CdGa_2Se_4$ single crystal thin films measured from Hall effect by van der Pauw method are $8.27{\times}10^{17}cm^{-3}$, $345\;cm^2/V{\cdot}s$ at 293 K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c-axis of the $CuInSe_2$ single crystal thin film, we have found that the values of spin orbit splitting ${\Delta}So$ and the crystal field splitting ${\Delta}Cr$ were 106.5 meV and 418.9 meV at 10 K, respectively. From the photoluminescence measurement on $CdGa_2Se_4$ single crystal thin film, we observed free excition ($E_x$) existing only high quality crystal and neutral bound exiciton ($D^{\circ}$, X) having very strong peak intensity. Then, the full-width-at -half-maximum(FWHM) and binding energy of neutral donor bound excition were 8 meV and 13.7 meV, respectivity. By Haynes rule, an activation energy of impurity was 137 meV.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2018.06a
• /
• pp.140-140
• /
• 2018

The 3D interconnect technologies have been appeared, as the density of Integrated Circuit (IC) devices increases. Through Silicon Via (TSV) process is an important technology in the 3D interconnect technologies. And the process is used to form a vertically electrical connection through silicon dies. This TSV process has some advantages that short length of interconnection, high interconnection density, low electrical resistance, and low power consumption. Because of these advantages, TSVs could improve the device performance higher. The fabrication process of TSV has several steps such as TSV etching, insulator deposition, seed layer deposition, metallization, planarization, and assembly. Among them, TSV metallization (i.e. TSV filling) was core process in the fabrication process of TSV because TSV metallization determines the performance and reliability of the TSV interconnect. TSVs were commonly filled with metals by using the simple electrochemical deposition method. However, since the aspect ratio of TSVs was become a higher, it was easy to occur voids and copper filling of TSVs became more difficult. Using some additives like an accelerator, suppressor and leveler for the void-free filling of TSVs, deposition rate of bottom could be fast whereas deposition of side walls could be inhibited. The suppressor was adsorbed surface of via easily because of its higher molecular weight than the accelerator. However, for high aspect ratio TSV fillers, the growth of the top of via can be accelerated because the suppressor is replaced by an accelerator. The substitution of the accelerator and the suppressor caused the side wall growth and defect generation. The suppressor was used as Single additive electrodeposition of TSV to overcome the constraints. At the electrochemical deposition of high aspect ratio of TSVs, the suppressor as single additive could effectively suppress the growth of the top surface and the void-free bottom-up filling became possible. Generally, copper was used to fill TSVs since its low resistivity could reduce the RC delay of the interconnection. However, because of the large Coefficients of Thermal Expansion (CTE) mismatch between silicon and copper, stress was induced to the silicon around the TSVs at the annealing process. The Keep Out Zone (KOZ), the stressed area in the silicon, could affect carrier mobility and could cause degradation of the device performance. Cobalt can be used as an alternative material because the CTE of cobalt was lower than that of copper. Therefore, using cobalt could reduce KOZ and improve device performance. In this study, high-aspect ratio TSVs were filled with cobalt using the electrochemical deposition. And the filling performance was enhanced by using the suppressor as single additive. Electrochemical analysis explains the effect of suppressor in the cobalt filling bath and the effect of filling behavior at condition such as current type was investigated.

• Clean Technology
• /
• v.21 no.4
• /
• pp.224-228
• /
• 2015

Phospholipase D (PLD) was immobilized on a submicro-porous membrane through covalent immobilization. The immobilization was conducted on the porous membrane surface with the treatment of polyethyleneimine, glutaraldehyde, and the anhydrase, in sequence. The immobilization was confirmed using X-ray photon spectrometer. The pH values of phosphatidylcholine (PC) dispersion solution with buffer were monitored with respect to time to calculate the catalytic activities of PC for free and immobilized PLD. The catalytic rate constant values for free PLD, immobilized PLD on polystyrene nanoparticles, and immobilized PLD on a porous cellulose acetate membrane were 0.75, 0.64, and 0.52 s^-1, respectively. Reusability was studied up to 10 cycles of PC hydrolysis. The activity for the PLD immobilized on the membrane was kept to 95% after 10 cycles, and comparable to the PLD on the nanoparticles. The stabilities for heat and storage were also investigated for the three cases. The results suggested that the PLD immobilized on the membrane had the least loss rate of the activity compared to the others. From these studies, the porous membrane was feasible as a carrier for the PLD immobilization in the production of phosphatidic acid.