• Nuclear Engineering and Technology
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• v.53 no.12
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• pp.4093-4097
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• 2021

This study presents a new dead-time measurement method using the gamma attenuation law and generalized dead-time models for nuclear gamma-ray detectors. The dead-time of the NaI(Tl) detection system was obtained to validate the new dead-time determination method using very thin lead and polyethylene absorbers. Non-paralyzing dead-time was found to be 8.39 ㎲, and paralyzing dead-time was found to be 8.35 ㎲ using lead absorber for NaI(Tl) scintillator detection system. These dead-time values are consistent with the previously reported dead-time values for scintillator detection systems. The gamma build-up factor's contribution to the dead-time was neglected because a very thin material was used.

• Journal of radiological science and technology
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• v.44 no.4
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• pp.343-350
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• 2021

3D printing technology is an additive manufacturing technology produced through 3D scanning or modeling method. This technology can be produced in a short time without mold, which has recently been applied in earnest in various fields. In the medical field, 3D printing technology is used in various fields of radiology and radiation therapy, but related research is insufficient in the field of nuclear medicine. In this study, we compare the characteristics of traditional nuclear medicine phantom with 3D printing technology and evaluate its applicability in clinical trials. We manufactured the same size phantom of poly methyl meta acrylate(PMMA) and acrylonitrile butadiene styrene(ABS) based on the aluminum step wedge. We used BrightView XCT(Philips Health Care, Cleveland, USA) SPECT/CT. We acquired 60 min list mode for Aluminum, PMMA and ABS phantoms using Rectangular Flood Phantom (Biodex, New York, USA) ^99mTcO₄ 3 mCi(111 MBq), 6 mCi (222MBq) and ⁵⁷Co Flood phantom(adq, New Hampshire, USA). For the analysis of acquired images, the region of interest(ROI) were drawn and evaluated step by step for each phantom. Depending on the type of radioisotope and radiation dose, the counts of the ABS phantom was similar to that of the PMMA phantom. And as the step thickness increased, the counts decreased linearly. When comparing the linear attenuation coefficient of Aluminum, PMMA and ABS phantom, the linear attenuation coefficient of the aluminium phantom was higher than that of the others, and the PMMA and ABS phantom had similar the linear attenuation coefficient. Based on ABS phantom manufactured by 3D printing technology, as the thickness of the PMMA phantom increased, the counts and linear attenuation coefficient decreased linearly. It has been confirmed that ABS phantom is applicable in the clinical field of nuclear medicine. If the calibration factor is applied through further research, it is believed that practical application will be possible.

• Journal of mucopolysaccharidosis and rare diseases
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• v.2 no.2
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• pp.46-49
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• 2016

Achondroplasia is autosomal dominant genetic disease and fibroblast growth factor receptor 3 (FGFR3) is currently known to be the only gene that causes achondroplasia. Gain-of function mutation in fibroblast-growth-factor-receptor 3 (FGFR3) causes the disease and C-type natriuretic peptide (CNP) antagonizes FGFR3 downstream signaling by inhibiting the pathway of mitogen-activated protein kinase (MAPK). As FGFR3-related skeletal dysplasias are caused by growth attenuation of the cartilage, chondrocytes appear to be unique in their response to FGFR3 activation. However, the full spectrum of molecular events by which FGFR3 mediates its signaling is just beginning to emerge. This article summaries the mechanisms of FGFR3 function in skeletal dysplasias, the extraordinary cellular manifestations of FGFR3 signaling in chondrocytes, and finally, the progress toward therapy for ACH.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.8
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• pp.1193-1198
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• 2003

An increase in frequency of administration of exogenous growth hormone (GH) or GH-releasing hormone was reported to be a model to increase blood circulating insulin-like growth factor-1 (IGF-1) and to improve growth performance in animals. We have investigated the effect of twice daily administration of GH-releasing peptide-2 (GHRP-2) on growth performance, GH responsiveness and plasma insulin-like growth factor IGF-1 in swine. We administered to eight swine, 3 control and 5 treatment, a twice daily s.c. injections of GHRP-2 ($30{\mu}g/kg\;BW$) for a period of 10 days. Every day blood samples immediately taken before injections of GHRP-2 or saline, at 08:00 h and 16:00 h, were measured for IGF-1 concentrations. Blood samples for GH assay were collected every 20 min on days 1, 6 and 10, from 1 hour before and 3 h after GHRP-2 or saline injections at 08:00 h. GH peak concentrations and GH area under curve (GH AUC) on day 1, 6 and 10 in treatment group of swine were higher than those in control swine (p<0.05). Twice daily administration of GHRP-2 caused a significantly attenuation (p<0.05) of GH peak concentrations ($80.25{\pm}13.87$, $39.73{\pm}5.72$ and $27.57{\pm}6.06ng/ml$ for day 1, 6 and 10, respectively) and GH AUCs ($3,536.15{\pm}738.35$, $1,310.31{\pm}203.55$ and $934.37{\pm}208.99ng/ml$ for day 1, 6 and 10, respectively). However, there was no significant difference in GH peak concentration and GH AUC between day 6 and 10. Plasma IGF-1 concentration levels were higher in treatment than control group of swine (p<0.05) after 3 days of the treatment, and the levels reached a plateau from day 3 to 10 of experiment. Growth performance did not alter by GHRP-2 administration, even though a numerical increase of body weight gain and feed efficiency was observed. These results indicate that twice daily administration of GHRP-2 for 10 days in swine did not significantly influence on growth performance, caused an overall attenuation of GH response, and that elevation of plasma GH concentrations caused by GHRP-2 administration increased plasma IGF-1 concentrations, even though an attenuation of GH response was observed.

• Progress in Medical Physics
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• v.9 no.4
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• pp.259-266
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• 1998

To achieve the 2D dose distribution around the designed high dose rate Ir-192 source substitution for Co-60 brachytherapy source, we determined the exposure rate constant and tissue attenuation factors as a large depth as a 20 cm from source center. The exposure rate constant is used for apparent activity in designed source with self-absorption and encapsulation steel wall. The tissue dose delivered from the 4401 segments of 2.5 mm in a diameter and 2.5 mm height of disk-type source layer. In the experiments, the tissue attenuation factors include the tissue attenuation and multiple scattering in a medium surrounding the source. The fitted the polynomial regression with 4th order for the tissue attenuation factors are very closed to the experimental measurement data within ${\pm}$1% discrepancy. The Meisberger's constant showed the large uncertainty in large distance from source. The exposure rate constant 4.69 Rcm$^2$/mCi-hr was currently used for determination of apparent activity of source and air kerma strength was obtained 0.973 for tissue absorbed dose from the energy spectrum of Ir-192 source. In our experiments with designed high dose rate brachytherapy source, the apparent activity of Ir-192 source was delivered from the 54.6 % of actual physical source activity through the self-absorption and encapsulation wall attenuations. This paper provides the 2-dimensional dose tabulation from unit apparent activity in a water medium for dose planning includes the multiple scattering, source anisotropy effect and geometric factors.

• Interaction and multiscale mechanics
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• v.3 no.2
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• pp.145-156
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• 2010

The propagation of waves in a micropolar transversely isotropic half space in the theory of thermoelasticity without energy dissipation are discussed. After developing the solution, the phase velocities and attenuation quality factor has been obtained. The expressions for amplitudes of stresses, displacements, microrotation and temperature distribution have been derived and computed numerically. The numerical results have been plotted graphically.

• BMB Reports
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• v.42 no.2
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• pp.106-112
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• 2009

The bio-complex "reaction pattern in vertebrate cells"(RiV) is mainly represented by characteristic exosome-like particles - probably as reaction products of cells to specific stress. The transcription factor NF-kappaB plays a central role in inflammation. We tested the hypothesis that RiV particle preparations (RiV-PP) reduce cellular adhesion molecule (CAM) expression (ICAM-1, VCAM-1, E-selectin) by the attenuation of NF-kappaB translocation in human umbilical vein endothelial cells (HUVEC). After 4 hours, pre-incubation of HUVEC with RiV-PP before stimulation with TNF-alpha significantly reduced ICAM-1 (65.5${\pm}$10.3%) and VCAM-1 (71.1${\pm}$12.3%) mRNA expression compared to TNF-alpha-treated cells (100%, n=7). ICAM-1 surface expression was significantly albeit marginally reduced in RiV/TNF-alpha- treated cells (92.0${\pm}$5.6%, n=4). No significant effect was observed on VCAM-1 surface expression. In RiV/TNF-alpha-treated cells (n=4), NF-kappaB subunits p50 (85.7${\pm}$4.1%) and p65 (85.0${\pm}$1.8%) nuclear translocation was significantly reduced. RiV-PP may exert an anti-inflammatory effect in HUVEC by reducing CAM mRNA expression via attenuation of p50 and p65 translocation.

• Nuclear Engineering and Technology
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• v.56 no.7
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• pp.2821-2827
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• 2024

This investigation developed a novel polyester composite based on the addition of zinc oxide (ZnO) of different sizes. We prepared nine samples Containing different percentages and sizes of ZnO as well as the control sample (Pol-ZnO0). The attenuation factors of Pol-micro ZnO were estimated using Phy-x software, while the HPGe detector and various gamma sources were used to experimentally measure the all-prepared composites. In terms of the two methods for micro composites, good agreement was observed. The linear attenuation coefficient (LAC) of Pol-ZnO20, Pol-ZnO40, and Pol-ZnO60, two more samples one with ZnO nanoparticles instead of microparticles, and the other with half microparticles and half nanoparticles (referenced as 0.5 M + 0.5 N) were determined. For all the Polyester composites and energies, the mixture of microparticles and nanoparticles had greater LAC values than each of the particles on their own. For example, the LAC values for the Pol-ZnO20 polymer at 1.330 MeV are 0.0836, 0.0888, and 0.0903 cm^-1 for the microparticles, nanoparticles, and mixture, respectively. The values of the prepared polymer samples' radiation protection efficiency (RPE) against energy with a thickness of 2 cm was determined experimentally. The Pol-ZnO60 0.5 M + 0.5 N sample has the highest RPE out of all the samples, followed by its nanoparticle counterpart, and then its microparticle counterpart. On the other hand, the Pol-ZnO0 sample, the polymer with no ZnO content, at all energies has the lowest RPE, followed by the three Pol-ZnO20 samples.

• BMB Reports
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• v.50 no.11
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• pp.539-545
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• 2017

The Integrated Stress Response (ISR) refers to a signaling pathway initiated by stress-activated $eIF2{\alpha}$ kinases. Once activated, the pathway causes attenuation of global mRNA translation while also paradoxically inducing stress response gene expression. A detailed analysis of this pathway has helped us better understand how stressed cells coordinate gene expression at translational and transcriptional levels. The translational attenuation associated with this pathway has been largely attributed to the phosphorylation of the translational initiation factor $eIF2{\alpha}$. However, independent studies are now pointing to a second translational regulation step involving a downstream ISR target, 4E-BP, in the inhibition of eIF4E and specifically cap-dependent translation. The activation of 4E-BP is consistent with previous reports implicating the roles of 4E-BP resistant, Internal Ribosome Entry Site (IRES) dependent translation in ISR active cells. In this review, we provide an overview of the translation inhibition mechanisms engaged by the ISR and how they impact the translation of stress response genes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.628-631
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• 2003

In this paper, 2.4 GHz WLAN BPF(Band Pass Filter) using LTCC(Low temperature cofiring ceramic) multilayer technology was simulated and manufactured. A modified ${\lambda}/4$ Hair-pin resonator with shunt-to ground loaded capacitor is used to shorten resonator length and improve circuit Q factor. Proposed BPF has a combline structure. Electro-magnetic Coupling between coupled strip-line resonators is controlled to provide attenuation poles at finite frequencies. The overall size of the filter is $3.2{\times}1.6{\times}1.3mm^3$. The measured result shows good agreement with simulated data.