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Reference thermal neutron field at KRISS for calibration of neutron detectors
Kim, Yun Ho,Park, Hyeonseo,Kim, Yong Kyun,Kim, Jungho,Kang, Jeongsoo Elsevier 2017 Radiation measurements Vol.107 No.-
<P><B>Abstract</B></P> <P>A reference thermal neutron field has been established at the Korea Research Institute of Standards and Science (KRISS) by using a <SUP>241</SUP>Am-Be neutron source and a high-purity graphite pile constructed by stacking graphite blocks. The properties of the graphite blocks such as impurities, density, and dimensions were studied thoroughly to understand the characteristics of the generated field. The energy spectrum and thermal neutron fractions were simulated with the Monte Carlo N-Particle eXtended code using measured physical parameters. The neutron effective temperature was 308 K, and the fraction of thermal neutrons was approximately 95% at the reference position of the thermal neutron field. The thermal neutron fluence rate was determined by adopting the Westcott convention method based on neutron activation analysis using a gold foil. The Westcott fluence rate for thermal neutron at the reference position was (2326.7 ± 8.4) cm<SUP>−2</SUP>s<SUP>−1</SUP>. The true thermal neutron fluence rate at the reference position in the KRISS thermal neutron field was (2700 ± 29) cm<SUP>−2</SUP>s<SUP>−1</SUP> (at the reference date of June 30, 2014). The response of a spherical proportional counter with He-3 (SP9 neutron detector) was evaluated in the newly established field as (3.083 ± 0.045) cm<SUP>2</SUP> for the reference calibration condition (a parallel neutron beam with a Maxwellian energy distribution having a most probable energy of 0.025 eV).</P> <P><B>Highlights</B></P> <P> <UL> <LI> Thermal neutron field was developed for the calibration of neutron detectors. </LI> <LI> A <SUP>241</SUP>Am-Be neutron source and a pure graphite pile were used for the construction. </LI> <LI> Monte Carlo simulation was performed to understand characteristics of the field. </LI> <LI> Thermal neutron fluence rate was determined based on neutron activation analysis. </LI> <LI> The sensitivity of the SP9 detector was calibrated with an uncertainty of ∼3%. </LI> </UL> </P>
( Jeongsoo Kim ),( Seha Park ),( Seulki Lee ),( Haryeong Ryu ),( Heejoo Kim ),( Jooyoung Roh ),( Hyangjoon Park ),( Jinok Baek ) 대한피부과학회 2017 대한피부과학회 학술발표대회집 Vol.69 No.2
Background: Cafe-au-lait macules (CALMs) are benign cutaneous hyperpigmentary disorders. Usually, laser therapies for cosmetic concerns result in more severe side effects in the people of Asian descent than that of Caucasians. Unfortunately, there is no gold standard for the laser treatment of CALMs in skin of people of Asian descent. Objectives: To investigate the efficacy and safety of a high fluence 1064-nm Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser treatment of CALMs in Asian patients. Methods: The medical records of thirty-five Korean patients (age range: 1 to 40 years old, mean age : 18.5 years) diagnosed with isolated CALMs were reviewed retrospectively. The patients were treated with a 1064-nm Q-switched Nd:YAG laser. The parameters were a spot size of 7 mm, a fluence of 2.2-2.4 J/cm2 with a slow single sliding-stacking pass, and a pulse rate of 10Hz with a one-week interval for 20-50 sessions. Results: At the week of the final treatment, all treated CALMs showed considerable pigmentation removal without any permanent side effects, such as scaring, mottled hypopigmentation, and post-inflammatory hyperpigmentation (PIH). All treated CALMs showed more than 50% clinical improvement. No recurrence was observed in any of the patients after 12 months of follow up. Conclusion: A high fluence 1064-nm Q-switched Nd:YAG laser treatment of CALMs in Asian patients is a safe and effective method without side effects and recurrence.
( Jeongsoo Kim ),( Seha Park ),( Seulki Lee ),( Haryeong Ryu ),( Jinok Baek ),( Jooyoung Roh ),( Hyangjoon Park ),( Heejoo Kim ) 대한피부과학회 2017 대한피부과학회 학술발표대회집 Vol.69 No.2
Background: Eosinophilic cytokine profile including IL-23/Th17 axis and their immunomodulatory interaction with other immune cells imply their possible involvement in psoriasis pathogenesis. Objectives: This study was to examine the potential role of eosinophils in imiquimod (IMQ)-induced psoriasiform dermatitis using ΔdblGATA mice, an eosinophil lineage-ablated mouse line. Methods: After topical IMQ application, inflammatory cytokine gene expression and Inflammatory cell populations were analyzed by qRT-PCR and flow cytometry, respectively. Results: Psoriatic features like epidermal thickening, erythema, and scale were less prominent in ΔdblGATA mice after IMQ treatment. Inflammatory cytokines important in psoriasis, like IL-1β, IL-6, IL-22, IL-23, and IL-17, and Th1-/neutrophil-related chemokines CCL2 and CXCL12 were also downregulated, and neutrophils were constantly decreased in the skin, LN, and spleen of ΔdblGATA mice compared to WT mice after IMQ treatment. Although IMQ application increased eosinophils in the skin of WT mice, the absolute cell count was much lower than neutrophils, a major player in psoriasis. Conclusion: The small size of eosinophil population and constant reduction of neutrophil in ΔdblGATA mice than WT mice after IMQ treatment suggest that eosinophils would influence psoriasis indirectly via their inflammatory profile and affecting other mediators in psoriasis, such as neutrophils.
[P231] Hair collar sign in an infant with aplasia cutis congenita associated with nevus flammeus
( Jeongsoo Kim ),( Seha Park ),( Seul Ki Lee ),( Ha Ryeong Ryu ),( Heejoo Kim ),( Jinok Baek ),( Hyang Joon Park ),( Joo Young Roh ) 대한피부과학회 2017 대한피부과학회 학술발표대회집 Vol.69 No.1
Aplasia cutis congenita (ACC) is a heterogeneous group of disorders in which localized or widespread areas of skin are absent at birth. ACC manifests as a solitary defect on the scalp in 70% of cases. Although most commonly seenon the scalp, ACC can affect any part of the body. Although pathogenesis of ACC is still unclear, proposed hypotheses are divided into two categories : endogenous causes (developmental failure, congenital syndromes) and exogenous ones (intrauterine trauma, infarction, skin fissure caused by rapid growth). Hair collar sign is a ring of darker and coarser terminal hairs on the scalp, typically surrounding ACC, dermoid cyst, encephalocele, or meningocele. It has been described as a relatively specific marker of neuroectodermal defect. A 5-month-old boy presented with round bald patches with underlying a large reddish patch on posterior occiput. It was surrounded by a rim of terminal hairs. Hair collar sign can be a specific clue for diagnosing ACC. Pregnancy and the delivery had been unremarkable and the baby wasotherwise healthy. Histopathology of the skin showed flattened epidermis, vascular dilatation in the superficial dermis, thickening of vessel walls in the reticular dermis, and absence of adnexal structures. It is assumed that association of ACC with nevus flammeus is that fetal skin development including capillary network formation might have been affected since cranial tube was not closed properly.