• Journal of Sensor Science and Technology
• /
• v.19 no.6
• /
• pp.443-448
• /
• 2010

In this work, the scintillation properties of CsI:Na crystal were investigated as radiation detection sensor. This scintillation material was grown by a 2-zone vertical Bridgman method. Under X-ray excitation the crystal shows a broad emission band between 280 nm and 690 nm wavelength range, peaking at 413 nm. Energy resolution for $^{137}Cs$ 662 keV $\gamma$-rays of the crystal was measured to be 6.9 %(FWHM). At room temperature, the crystal exhibits three exponential decay time components. The fast and major component of scintillation time profile of the crystal emission decays with a 457 ns time constant. Absolute light yield of the crystal was estimated to be 53,000 ph/MeV using LAAPD. The sample crystal shows proportionality of 30 % in the measured energy range from 31 to 1,333 keV. And the $\alpha/\beta$ ratio of the crystal was 0.14.

• The Korean Journal of Physiology and Pharmacology
• /
• v.9 no.6
• /
• pp.353-361
• /
• 2005

The interaction of cyclosporine A (CsA), an immunosuppressant, with rat brain Kv1.5 (Kv1.5) channels, which were stably expressed in Chinese hamster ovary cells, was investigated using the whole-cell patch-clamp technique. CsA reversibly blocked Kv1.5 currents at +50 mV in a reversible concentrationdependent manner with an apparent $IC_{50}$ of 1.0μM. Other calcineurin inhibitors (cypermethrin, autoinhibitory peptide) had no effect on Kv1.5 and did not prevent the inhibitory effect of CsA. Fast application of CsA led to a rapid and reversible block of Kv1.5, and the onset time constants of the CsA-induced block were decreased in a concentration-dependent manner. The CsA-induced block of Kv1.5 channels was voltage-dependent, with a steep increase over the voltage range of channel opening. However, the block exhibited voltage independence over the voltage range in which channels were fully activated. The rate constants for association and dissociation of CsA were $7.0{\mu}M{-1}s^{-1}$ and $8.1s^{-1}$, respectively. CsA slowed the deactivation time course, resulting in a tail crossover phenomenon. Block of Kv1.5 by CsA was use-dependent. CsA also blocked Kv1.3 currents at +50 mV in a reversible concentration-dependent manner with an apparent $IC_{50}$ of $1.1{\mu}M$. The same effects of CsA on Kv1.3 were also observed in excised inside-out patches when applied to the internal surface of the membrane. The present results suggest that CsA acts directly on Kv1.5 currents as an open-channel blocker, independently of the effects of CsA on calcineurin activity.

• Korean Journal of Otorhinolaryngology-Head and Neck Surgery
• /
• v.60 no.3
• /
• pp.107-111
• /
• 2017

Background and Objectives The bedside head impulse test (bHIT) in bare eyes often overlooks possible vestibular losses by missing the corrective saccade. This is why it is necessary to compare bHIT against video head impulse test (vHIT), which is more accurate in identifying vestibular losses than the bedside test. Subjects and Method A total of 51 vHIT positive ears underwent the study, and out of those, 47 were diagnosed with dizziness. bHIT and vHIT were performed for patients, and the occurrence rate of overt saccade (OS) was calculated. Results Among the 51 vHIT positive ears, 33 (64.7%) were bHIT positive ears and 18 ears (35.3%) were bHIT negative. Patterns of positive vHIT were classified as A: no corrective saccade, B: covert saccade (CS) only, C: OS only, and D: CS with OS (CS+OS), which were 45 out of 51 ears (88%). The occurrence rate of OS was higher in the bHIT positive group than in the bHIT negative group (p=0.05), and higher in the CS negative group (CS-) than in the CS positive group (CS+) (p<0.001). Conclusion Possible causes of false negative results of bHIT are seen as following: the absence of corrective (covert and overt) saccade, the occurrence of CS only, and missing the OS during the bHIT (probably due to low occurrence rate of OS). The occurrence of CS should be considered as an important factor in false negative bHIT when lowering the occurrence rate of OS.

• Journal of Radiation Protection and Research
• /
• v.29 no.4
• /
• pp.263-268
• /
• 2004

Using the Monte Carlo simulation, a study on the lion-proportionality of the prototype phoswich detector with $2'{\times}2'$ CSI(Tl) and plastic scintillator, which was made by KAERI, has been carried. The defector response functions (DRFs) calculated by simulations were compared with the experimental measurement on the $^{137}Cs\;and\;^{60}Co$. To precisely simulate the DRF for the phoswich, the CSI(Tl) non-proportionality was calculated using the electron response and the simplified electron cascade sequence for treating the photoelectric absorption event. The resulting DRFs of $^{137}Cs\;and\;^{60}Co$ sources obtained by simulations were compared with experiments for verification. For $^{137}Cs$, gamma-ray responses simulated by MCNP5 are generally good agreement with the measured ones. But the DRF of $^{60}Co$ does not match well with the results of experiment in the energy region below second peak due to the coincidence effect of two gamma-rays (1.17 MeV and 1.33 MeV). Through the analysis of the non-proportionality of CsI(Tl) in the prototype phoswich, the improved DRFs considering non-proportionality were produced and the simulation results were verified using the experimental measurements. However, to more precisely reproduce the DRF for the phoswich, further studies in relation to the electron channeling effect and the Doppler broadening effect of a scintillator are still needed as well as considering that effect of the transfer contribution.

• Horticultural Science & Technology
• /
• v.32 no.3
• /
• pp.318-329
• /
• 2014

In order to gain insight into the physiological responses of plants to high temperature stress, the effects of temperature on Chinese cabbage (Brassica campestris subsp. napus var. pekinensis cv. Detong) were investigated through analyses of photosynthesis and chlorophyll fluorescence under 3 different temperatures in the temperature gradient tunnel. Growth (leaf length and number of leaves) during the rosette stage was greater at ambient $+4^{\circ}C$ and ambient $+7^{\circ}C$ temperatures than at ambient temperature. Photosynthetic $CO_2$ fixation rates of Chinese cabbage grown under the different temperatures did not differ significantly. However, dark respiration rate was significantly higher in the cabbage that developed under ambient temperature relative to elevated temperature. Furthermore, elevated growth temperature increased transpiration rate and stomatal conductance resulting in an overall decrease of water use efficiency. The chlorophyll a fluorescence transient was also considerably affected by high temperature stress; the fluorescence yield $F_J$, $F_I$, and $F_P$ decreased considerably at ambient $+4^{\circ}C$ and ambient $+7^{\circ}C$ temperatures, with induction of $F_K$ and decrease of $F_V/F_O$. The values of RC/CS, ABS/CS, TRo/CS, and ETo/CS decreased considerably, while DIo/CS increased with increased growth temperature. The symptoms of soft-rot disease were observed in the inner part of the cabbage heads after 7, 9, and/or 10 weeks of cultivation at ambient $+4^{\circ}C$ and ambient $+7^{\circ}C$ temperatures, but not in the cabbage heads growing at ambient temperature. These results show that Chinese cabbage could be negatively affected by high temperature under a future climate change scenario. Therefore, to maintain the high productivity and quality of Chinese cabbage, it may be necessary to develop new high temperature tolerant cultivars or to markedly improve cropping systems. In addition, it would be possible to use the non-invasive fluorescence parameters $F_O$, $F_V/F_M$, and $F_V/F_O$, as well as $F_K$, $M_O$, $S_M$, RC/CS, ETo/CS, $PI_{abs}$, and $SFI_{abs}$ (which were selected in this study), to quantitatively determine the physiological status of plants in response to high temperature stresses.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.41 no.5
• /
• pp.99-105
• /
• 2004

A shared-capacitor charge-sharing ROM (SCCS-ROM) using dummy bit lines is proposed. The SCCS-ROM reduces the bit line swing voltage using the charge-sharing technique of the conventional charge-sharing ROM (CS-ROM). Although the CS-ROM needs three small capacitors per output bit, the proposed SCCS-ROM shares the capacitors so that it needs only three capacitors. The SCCS-ROM implements the capacitors using dummy bit lines. This not only increases noise immunity but also reduces power. A SCCS-ROM with 8K${\times}$15bits implemented in a 0.35${\mu}{\textrm}{m}$ CMOS process. The SCCS-ROM consumes 8.63㎽ at 100MHz with 3.3V The simulation results show that the SCCS-ROM reduces 8.4% power compared to the CS-ROM.

• Childhood Kidney Diseases
• /
• v.4 no.2
• /
• pp.127-135
• /
• 2000

Purpose: Cyclosporine(CsA) is a potent immunosuppressant but the use of CsA is associated with various side effects, especially nephrotoxicity. In tile kidney, salt depletion activates tile renin-angiotensin-aldosteron(RAS) system and accentuates chronic CsA nephropathy. We postulate that angiotensin converting enzyme inhibitors(ACEI) can prevent chronic CsA nephropathy, since ACEI may inhibit this cascades. This study was aimed to assess the effect of ACEI on chronic cyclosporin nephropathy in salt depleted rats. Methods: 36 Fischer-344 rats were divided into 6 goups. Group I received normal salt diet(NSD). Group II received a low salt diet(LSD). Group III received CsA with a NSD. Group IV received CsA with a LSD. Group V received NSD+CsA with ACEI. Group VI received LSD+CsA with ACEI. Rats were sacrificed after six weeks and the glomerular filtration rate(GFR), serum sodium, potassium and whole blood cyclosporine levels were measured. Renal tissues me sampled for the observation of histological changes. Results: No differences in blood CsA level & serum sodium were found between groups during the course of this experiment. Serum potassium in group VI was significantly increased compared with group IV and V (P<0.05). In groups treated with CsA only and in those where CsA was combined with ACEI, GFR was found to be significantly more decreased in LSD than NSD, and GFR in group V was significantly decreased in comparison with group III (P<0.05). Renal histologic lesions associated with CsA which consisted of cortical interstitial fibrosis, tubular atrophy and hyalinization of arterioles were more severe in tile LSD group. But, no differences were observed between tile groups treated with CsA and ACEI, and the groups treated with only CsA. Conclusion: Salt depletion associated with the activation of the RAS system accentuated chronic CsA nephrotoxicity, but, ACEI could not reduce the functional and morphological changes of salt depleted kidneys, in which nephropathy can be exacerbated in spite of the blocking of the angiotensin II pathway. further studies are required to elucidate whether Am ameliorated the effect of salt-depleted CsA nephrotoxicity upon the effective renal blood flow.

• YAKHAK HOEJI
• /
• v.39 no.4
• /
• pp.360-366
• /
• 1995

1-$\beta$-Methyl carbapenem-2-substituted pyrroudine derivatives. CRB 529 and CRB 550, were synthesized as investigational carbapenem derivatives. It has been reported that the in vitro antibacterial activities of the compounds against G(+) and G(-) bacteria were almost the same or more effective than those of imipenem (IPM) and meropenem (MEPM), and also showed better in vivo efficacy than MEPM and inlipeneni/cilastatin (IPM/CS) against representative G(-) organisms, P. aeruginosa and MRSA organisms, S. aureus. The antibacterial activities, pharmacokinetics and protective efficacy of IPM/CS and CRB 529 and CRB 550 wereconducted after subcutaneous or intravenous administration to mice and rats. The pharmacokinetic parameters of CRB 529 and CRB 550 in mice were as follows: the observed maximal serum concentrations (C$_{max}$) following I.V. administration were 87.5 and 101 $\mu\textrm{g}$/ml for CRB 529 and CRB 550, respectively, and 63.6 $\mu\textrm{g}$/ml for IPM/CS. The half-lives (t$_{1/2}$) were 14.0 and 12.0 n-dn for CRB 529 and CRB 550, respectively, and 14.8 min for IPM/CS. In rats, $C_{max}$ after I.V. administration were 74.0 and 91.8 $\mu\textrm{g}$/ml for CRB 529 and CRB 550, respectively, and 41.2 $\mu\textrm{g}$/ml for IPM/CS. The tissue levels of CRB 529 and CRB 550 and IPM/CS after I.V. administration at a dose of 20 mg/kg decreased by the following order: lung, heart, kindney, liver and spleen for CRB 529, lddney, liver. lung, heart and spleen for CRB 550 and kidney, lung, liver, heart, spleen and brain for IPM/CS. In systemic infection, CRB 529 and CRB 550 showed excellent efficacies against P. aeruginosa and S. aureus (MRSA) at a dose of 5 mg/kg. The PD$_{50s}$ were 0.80, 0.36 mg/kg for CRB 529 and CRB 550, respectively, and 3.22 mg/kg for IPM/CS against P. aeruginosa. The corresponding values against S. aureus (MRSA) were 76.0, 55.3 mg/kg for CRB 529 and CRB 550, respectively, and 146 mg/kg for IPM/CS. In local infection, the antibacterial activities of CRB 529 and CRB 550 were more effective than those of IPM/CS against intrarenal infection with E. coli and P. aeruginosa and also showed as effective as IPM/CS against respiratory tract infection with E. coli and P. aeruginosa at a dose of 5 mg/kg.

• Journal of Sensor Science and Technology
• /
• v.6 no.4
• /
• pp.290-297
• /
• 1997

In this study, the radiation monitoring system using CsI(TI) scintillation counter is developed for the measurement of radiation distribution in the field of high dose level. When the inner diameter of collimator is 8 mm, we have realized the optimum detecting efficiency and spatial resolution. At that time, the position resolution was 10 cm at 1 m from the system. And experimental results indicated that the energy resolution of the system were 10 % for 662 keV of Cs-137, 7.6 % for 1.17 MeV of Co-60, and 5.8 % for 1.33 MeV of Co-60. Also, we have shown that the real radiation distribution images may be obtained by our measurement system.

• Journal of the Korean Society of Radiology
• /
• v.12 no.2
• /
• pp.123-131
• /
• 2018

This study compared PENELOPE with measured values from low energy peak to high energy peak to reduce peak to compton ratio and continuum background spectrum using $^{60}Co$, $^{137}Cs$ and mixed volume source. In addition, the change in backscattering and compton edge efficiency was compared with that of PENELOPE through changes in the vicinity of low energy. The results from the mixed volume source are applied to the soil samples to determine how much the minimum detection limits of the soil samples are reduced in the suppression and unsuppressed mode. The compton suppression of the low energy region of $^{60}CO$ (1,173 keV) was considerable, and the Compton edge RF for the $^{137}Cs$ (661 keV) peak was 2.8. In particular, the $^{60}Co$ source emits coincidence gamma rays of 1,173.2 keV and 1,332.5 keV, so compton inhibition was reduced by approximately 21%. RF of compton edges of 1,173 keV and 1,332 keV emitted from a $^{60}Co$ source was 3.2 and 3.4, and the peak to compton edge ratio was improved to 8: 1. And Compared with Penelope, the uncertainty was well within 2%. In compton unsuppressed mode, MDA values of 661 keV, 1,173 keV and 1,332 keV were 0.535, 0.173 and 0.136 Bq/kg, respectively, but decreased in compton suppressed mode to 0.121, 0.00826 and 0.00728 Bq/kg. Thus, Compton suppressed could reduce the background radioactivity and the radioactivity contained in the detector itself.