• Sleep Medicine and Psychophysiology
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• v.4 no.1
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• pp.57-65
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• 1997

As jet lag of modern travel continues to spread, there has been an exponential growth in popular explanations of jet lag and recommendations for curing it. Some of this attention are misdirected, and many of those suggested solutions are misinformed. The author reviewed the basic science of jet lag and its practical outcome. The jet lag symptoms stemed from several factors, including high-altitude flying, lag effect, and sleep loss before departure and on the aircraft, especially during night flight. Jet lag has three major components; including external de synchronization, internal desynchronization, and sleep loss. Although external de synchronization is the major culprit, it is not at all uncommon for travelers to experience difficulty falling asleep or remaining asleep because of gastrointestinal distress, uncooperative bladders, or nagging headaches. Such unwanted intrusions most likely to reflect the general influence of internal desynchronization. From the free-running subjects, the data has revealed that sleep tendency, sleepiness, the spontaneous duration of sleep, and REM sleep propensity, each varied markedly with the endogenous circadian phase of the temperature cycle, despite the facts that the average period of the sleep-wake cycle is different from that of the temperature cycle under these conditions. However, whereas the first ocurrence of slow wave sleep is usually associated with a fall in temperature, the amount of SWS is determined primarily by the length of prior wakefulness and not by circadian phase. Another factor to be considered for flight in either direction is the amount of prior sleep loss or time awake. An increase in sleep loss or time awake would be expected to reduce initial sleep latency and enhance the amount of SWS. By combining what we now know about the circadian characteristics of sleep and homeostatic process, many of the diverse findings about sleep after transmeridian flight can be explained. The severity of jet lag is directly related to two major variables that determine the reaction of the circadian system to any transmeridian flight, eg., the direction of flight, and the number of time zones crossed. Remaining factor is individual differences in resynchmization. After a long flight, the circadian timing system and homeostatic process can combine with each other to produce a considerable reduction in well-being. The author suggested that by being exposed to local zeit-gebers and by being awake sufficient to get sleep until the night, sleep improves rapidly with resynchronization following time zone change.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.50 no.1
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• pp.59-65
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• 2024

For plasma cosmetics, it is important to ensure the long-term stability of plasma in the formulation. This study examined the suitability of containers for efficient plasma cosmetics development. By varying the surface area covered by the plasma, 4 cm², 25 cm², 75 cm², and 175 cm² containers were injected with cosmetic plasma, and the amount of nitric oxide (NO), the main active species of nitrogen plasma, was analyzed. As a result, the surface area and stability exposed to plasma tended to be inversely proportional, and it was most effective in a 4 cm² container. Furthermore, 25 mm, 40 mm, and 50 mm vials were treated with plasma, which resulted in relative long-term stability of NO at 25 mm, a smaller surface area of the container exposed to air. Water mist and stratified mist were selected as cosmetic formulations, and NO plasma was injected into the water layer to observe the changes in formulation properties and the state of the injected NO plasma. In both formulations, the amount of NO plasma injected was about 1.5 times higher in the water phase mist than in the stratified mist, and the stratified mist gradually decreased with time and was found to disappear after 3 weeks. The stability of the nitrogen plasma was studied at low temperature (4 ℃), room temperature (25 ℃), and high temperature (37 ℃, 50 ℃). As a result, it was found that the water mist did not affect the stability, but the stratified mist observed a color change in the oil phase layer. Overall, this study demonstrates the container suitability of nitrogen plasma and suggests the importance of ensuring the stability of injected nitrogen plasma in cosmetic formulations.

• Journal of the Korean Magnetics Society
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• v.19 no.3
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• pp.89-93
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• 2009

Amorphous $Ge_{1-x}Mn_x$ semiconductor thin films grown by low temperature vapor deposition were annealed, and their electrical and magnetic properties have been studied. The amorphous thin films were $1,000{\sim}5,000\;{\AA}$ thick. Amorphous $Ge_{1-x}Mn_x$ thin films were annealed at $300^{\circ}C$, $400^{\circ}C$, $500^{\circ}C$, $600^{\circ}C$ and $700^{\circ}C$ for 3 minutes in high vacuum chamber. X-ray diffraction analysis reveals that as-grown $Ge_{1-x}Mn_x$ semiconductor thin films are amorphous and are crystallized by annealing. Crystallization temperature of amorphous $Ge_{1-x}Mn_x$ semiconductor thin films varies with Mn concentration. Amorphous $Ge_{1-x}Mn_x$ thin films have p-type carriers and the carrier type is not changed during annealing, but the electrical resistivity increases with annealing temperature. Magnetization characteristics show that the as-grown amorphous $Ge_{1-x}Mn_x$ thin films are ferromagnetic and the Curie temperatures are around 130 K. Curie temperature and saturation magnetization of annealed $Ge_{1-x}Mn_x$ thin films increase with annealing temperature. Magnetization behavior and X-ray analysis implies that formation of ferromagnetic $Ge_3Mn_5$ phase causes the change of magnetic and electrical properties of annealed $Ge_{1-x}Mn_x$ thin films.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.477-483
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• 2008

$La_{0.7}Sr_{0.3}Co_{0.2}Fe_{0.8}O_{3-{\delta}$ oxide was synthesized by a citrate method and a typical dense membrane of perovskite oxide has been prepared using as-prepared powder by pressing and sintering at $1300^{\circ}C$. Precursor of $La_{0.7}Sr_{0.3}Co_{0.2}Fe_{0.8}O_{3-{\delta}$ prepared by citrate method was investigated by TGA and XRD. Metal-citrate complex in precursor was decomposed into perovskite oxide in the temperature range of $260{\sim}410^{\circ}C$ but XRD results showed $SrCO_3$ existed as impurity at less than $900^{\circ}C$. Electrical conductivity of membrane increased with increasing temperature but then decreased over $700^{\circ}C$ in air atmosphere ($Po_2=0.2atm$) and $600^{\circ}C$ in He atmosphere ($Po_2=0.01atm$) respectively due to oxygen loss from the crystal lattice. The oxygen permeation flux increased with increasing temperature and maximum oxygen permeation flux of $La_{0.7}Sr_{0.3}Co_{0.2}Fe_{0.8}O_{3-{\delta}$ membrane with 1.6 mm thickness was about $0.31cm^3/cm^2{\cdot}min$ at $950^{\circ}C$. The activation energy for oxygen permeation was 88.4 kJ/mol in the temperature range of $750{\sim}950^{\circ}C$. Perovskite structure of membrane was not changed after permeation test of 40 h and the membrane was stable without secondary phase change with 0.3 mol Sr addition.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.420-430
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• 2005

This study was performed to change the hydrophilic $NH_4Y$-zeolite to the hydrophobic one for removal of VOCs by removing the $Al^{3+}$ in the zeolite-structure to increase the Si/Al ratio, for which the three pelleted $NH_4Y$-zeolite samples were contacted separately with the steam of $400^{\circ}C$, $500^{\circ}C$ and $600^{\circ}C$, respectively, in a stainless steel column for 4 hours. Then extraction of the ex-structure aluminum of the hydrolyzed zeolites with the nitric acids of 0.25, 0.50, 0.75, and 0.10 M at $90^{\circ}C$ in 500 mL-flasks, respectively, according to steam temperature were followed. XRD analysises of the dealuminated zeolites showed that the peaks of the zeolites that had been hydrolyzed with the steams of both $500^{\circ}C$ and $600^{\circ}C$ are distorted more with the increase of the concentration of nitric acid used for extraction of the ex-structure aluminums, however, those hydrolyzed with steam of $400^{\circ}C$ became amorphous phase when treated with the all nitric acids of four concentrations. Also the EDX analysises showed that the BET surface areas and TPVS of the zeolites that had been hydrolyzed with the steam of $600^{\circ}C$ were increased with the concentration of the nitric acid when the nitric acids of 0.25 M and 0.5 M had been used but decreased when the nitric acids of 0.75 M and 1.0 M had been used. These results led to the conclusion that both the $600^{\circ}C$ and $500^{\circ}C$-steam and the 0.5 M-nitric acid are appropriate to change the hydrophilic $NH_4Y$-zeolites to the hydrophobic one, which were proven by the measurement of the benzene and tolune-adsorbing capacities showing the same trend as the BET surface area and TPV The Si/Al ratios and water-adsorbing capacities of the dealuminated zeolites were increased and decreased, respectively, with the concentration of the nitric acids so that it showed that the hydrophobicity is increased.

• Analytical Science and Technology
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• v.28 no.3
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• pp.182-186
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• 2015

In this study, the porous CuO/MnO₂ catalyst was prepared through the co-precipitation process from an aqueous solution of potassium permanganate (KMnO₄), manganese(II) acetate (Mn(CH₃COO)₂·4H₂O) and copper(II) acetate (Cu(CH₃COO)₂·H₂O). The phase change in MnO₂ was analyzed according to the reaction molar ratio of KMnO₄ to Mn(CH₃COO)₂. The reaction mole ratio of KMnO₄ to Mn(CH₃COO)₂·4H₂O was varied at 0.3:1, 0.6:1, and 1:1. The aqueous solution of Cu(CH₃COO)₂ was injected into a mixed solution of KMnO₄ and Mn(CH₃COO)₂ to 10~75 wt% relative to MnO₂. The Cu ion co-precipitates as CuO with MnO₂ in a highly dispersed state on MnO₂. The physicochemical property of the prepared CuO/MnO₂ was analyzed by using the TGA, DSC, XRD, SEM, and BET. The different phase types of MnO₂ were prepared according to the reaction mole ratio of KMnO₄ to Mn(CH₃COO)₂·4H₂O. The results confirmed that the porous CuO/MnO₂ catalyst with γ-phase MnO₂ was produced in the reaction mole ratio of KMnO₄ to Mn(CH₃COO)₂ as 0.6:1 at room temperature.

• Korean Journal of Microbiology
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• v.32 no.2
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• pp.155-162
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• 1994

Cells of Acinetobacter sp. strain JC1 DSM 3803, an aerobic monoxide-oxidizing bacterium, growing on glucose exhibited high catalase activity at the mid-exponential growth phase. The enzyme activity decreased gradually after then until the early stationary phase, increased again at the mid-stationary phase, and then decreased again thereafter. Cells growing on glucose was found to contain three kinds of catalses. Cat1, Cat2 and Cat3. The activities of Cat1 and Cat3 did change significantly during growth, but that of Cat2 exhibited significant variation. Cat3 was found to present only in cells growing on glucose, but not in cells growing on carbon monoxide of methanol. The activities of call and Cat3 in cell-free extracts were stable upon treatment with ethanol and chloroform, but decreased to some extent when the enzymewere treated with 2mM $H_2O_2$ and/or 3-amino-1,2,4-triazole (AT). Cat2 was found to be extremely sensitive to the ethanol-chloroform and $H_2O_2$ treatments, but was insensitive to the AT treatment. Cat1 exhibited enzyme activity after incubation for 1 min at 80$^{\circ}C$. Cat2 and Cat3 did not show enzyme activity after incubation for 1 min at 60$^{\circ}C$ and 70$^{\circ}C$, respectively. Cat2 was found to have peroxidase activity. Cat3 was purified to homogenity in seven steps. The molecular weight of the native enzyme was estimated to be 150,000. Sodium dodecyl sulfate-gel electrophoresis revealed two identical subunits of molecular weight 65,000. The enzyme was found to show two $K_m$ values of 39 mM and 58mM. The optimal pH for the enzyme activity was 7.0, but the activities at pH 6.0, 8.0, and 9.0, were found to be comparable to that at the optimal pH. The optimal temperature for the enzyme activity was found to be 40$^{\circ}C$. The enzyme also exhibited strong activity at 20$^{\circ}C$, 30$^{\circ}C$, and 50$^{\circ}C$. The purified enzyme was not affected by the ethanol-chloroform treatment. The enzyme, howerver, showed less than 10% of the original activity when it was treated with 12 mN AT, 0.1 mM $NaN_3$ of 1mM KCN.

• Korean Chemical Engineering Research
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• v.49 no.5
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• pp.541-547
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• 2011

Nanorod-clustered $MnO_2$ precursors with ${\alpha}$-, ${\beta}$-, and ${\gamma}$-phases are synthesized by hydrothermal reaction of $MnSO_45H_2O$ and $(NH_4)S_2O_8$. The formation of nanorod-clustered ${\beta}-MnO_2$ is particularly confirmed under the conditions of high reactant concentration and hydrothermal reaction at $150^{\circ}C$. The spinel $LiMn_2O_4$ nanorod-clusters are also prepared by lithiating the $MnO_2$ precursors, varying the concentration of lithiating agent ($LiC_3H_3O_2{\cdot}2H_2O$) and heat treatment temperature, and characterized for use as cathode material of lithium-ion batteries. As a result, the nanorod-clustered $LiMn_2O_4$ prepared from the ${\beta}-MnO_2$ at higher $LiC_3H_3O_2{\cdot}2H_2O$ concentration and the annealing at $800^{\circ}C$ is proven to show the cubic spinel structure and to achieve the high initial discharge capacity of 120 mAh/g.

• Journal of the Korean earth science society
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• v.37 no.7
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• pp.389-397
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• 2016

In order to investigate the light curve difference in visual and infrared wavelength of ${\delta}$ Scuti variable Bo Lyn, observations were performed using BOAO 1.8m reflecting telescope and an infrared detector, KASINICS, with J, H, and Ks filters. Infrared light curves of total 7 nights were obtained between March and April in 2011, and those were compared to the V-filter light curve to examine the differences in period, time of maximum light, amplitude, and shape. From the periodic analysis of infrared light curve, a single frequency of $f_1=10.712cycle/day$, $P=0.09335{\pm}0.00002days$ was obtained, and there was no difference in the period along different wavelengths. In the infrared light curve, a frequency of $2f_1$ was detected. This frequency well explains the asymmetric shape of light curve, one of the characteristics of high-amplitude ${\delta}$ Scuti variables. We compared the locations of the measured infrared maxima and the predicted maxima of V-filter, finding that the times of maxima were delayed about 0.3 phase at infrared wavelengths. Amplitude ratios were adopted to be ${\Delta}J/{\Delta}V=0.328$, ${\Delta}H/{\Delta}V=0.216$, and ${\Delta}Ks/{\Delta}V=0.211$, with the range of variation being smaller at longer wavelengths. It seems that the differences in the times of maxima and amplitude occurred because the changes in brightness of a pulsating variable star are mainly caused by the change in temperature.

• Journal of Wetlands Research
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• v.13 no.3
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• pp.567-579
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• 2011

Scirpus planiculmis is one of the most dominant species found in the Nakdong River estuary. In order to understand the recent changes in S. planiculmis and the environmental characteristics of the estuary, from 2005 to 2010, an analysis of the density, total dry biomass, tuber biomass, and distribution pattern of S. planiculmis as well as an analysis of the temperature, salinity, precipitation, barrage discharge, and soil texture of the estuary were conducted. In 2006, the density ranged from 10.1 to $87.6no./m^2$, but in 2009, it ranged from 0.4 to $2.2no./m^2$ in 2009 and drastic reductions were observed throughout the sampled areas in the Nakdong river estuary. In 2010, S. planiculmis was observed on the tidal flats of Myungji and Mangummerydeung, at a density of $18.3{\pm}7.7no./m^2$ and $17.5{\pm}20.7no./m^2$, respectively. Hence, S. planiculmis is considered to be in a recovery phase. The aboveground/belowground ratio reduced from $4.54{\pm}0.70$ in 2005 to $1.91{\pm}0.35$ in 2009, clearly showing a large decrease in the biomass amount of the aboveground than of the belowground. Tubers were distributed in the soil, with only 36.0% at the 0~15 cm depth but 64.0% at the 15~30 cm depth. Apparently, tubers were more likely to be found at 15~30 cm below the soil in the Nakdong River estuary. A drastic reduction in the S. planiculmis biomass in 2009 is possibly due to the high salinity in S. planiculmis habitats.