Magnetic Resonance Imaging Meets Fiber Optics: a Brief Investigation of Multimodal Studies on Fiber Optics- Based Diagnostic / Therapeutic Techniques and Magnetic Resonance Imaging

최종률,Sung Suk Oh 대한자기공명의과학회 2021 Investigative Magnetic Resonance Imaging Vol.25 No.4

Due to their high degree of freedom to transfer and acquire light, fiber optics can be used in the presence of strong magnetic fields. Hence, optical sensing and imaging based on fiber optics can be integrated with magnetic resonance imaging (MRI) diagnostic systems to acquire valuable information on biological tissues and organs based on a magnetic field. In this article, we explored the combination of MRI and optical sensing/imaging techniques by classifying them into the following topics: 1) functional near-infrared spectroscopy with functional MRI for brain studies and brain disease diagnoses, 2) integration of fiber-optic molecular imaging and optogenetic stimulation with MRI, and 3) optical therapeutic applications with an MRI guidance system. Through these investigations, we believe that a combination of MRI and optical sensing/imaging techniques can be employed as both research methods for multidisciplinary studies and clinical diagnostic/therapeutic devices.

Mechanical Design for an Optical-telescope Assembly of a Satellite-laser-ranging System

김도원,박상영,이혁교,강필성 한국광학회 2023 Current Optics and Photonics Vol.7 No.4

The structural design of an optical-telescope assembly (OTA) for satellite laser ranging (SLR) is conducted in two steps. First, the results of a parametric study of the major design variables (e.g. dimension and shape) of the OTA part are explained, and the detailed structural design of the OTA is derived, considering the design requirements. Among the structural-shape concepts of various OTAs, the Serrurier truss concept is selected in this study, and the collimation of the telescope according to the design variables is extensively discussed. After generating finite-element models for different structural shapes, self-gravity analyses are performed. To minimize the deflection and tilt of the mirror and frame for the OTA under the limited design requirements, a parametric study is conducted according to design variables such as the shapes of the upper and lower struts and the spider vane. The structural features found in the parametric study are described. Finally, the OTA structure is designed in detail to maintain the optical alignment by balancing the gravity deflections of the upper and lower trusses using the optimal combination of the parameters. Additionally, thermal analysis of the optical telescope design is evaluated.

Dielectric, electrical and optical properties of aluminosilicate ceramics synthesized by solid-state reaction route

Biswal Bijaylaxmi,Mishra Dilip Kumar,Mohapatra Jyoshnarani,Bhuyan Satyanarayan 한국세라믹학회 2022 한국세라믹학회지 Vol.59 No.5

The conventional high-temperature solid-state reaction technique is used to synthesize aluminosilicate ceramics of three different compositions (Al 0.70 Si 0.30 O, Al 0.73 Si 0.27 O, Al 0.75 Si 0.25 O). These aluminosilicate ceramics are systematically investigated by XRD, FTIR, SEM, dielectric, electrical, and UV–visible analysis. The polycrystalline ceramics are well synthesized at a sintering temperature of 1450 °C, confirmed from XRD studies. The IR interferogram reveals the presence of mullite (3Al 2 O 3 2SiO 2 )-type molecules in these aluminosilicate ceramics. The SEM images show the formation of homogeneous microstructures with appreciable density. The room temperature dielectric constant values for Al 0.70 Si 0.30 O, Al 0.73 Si 0.27 O, Al 0.75 Si 0.25 O ceramics are 1.5, 1.8, and 1.7 at 1 MHz frequency with dielectric loss values of 0.02, 0.04, and 0.06 respectively. The ac conductivity spectrum of these samples obeys the Arrhenius equation and the classical correlated barrier hopping model governs the conduction mechanism in these ceramics. Complex impedance analysis confirms the contribution of both grain and grain boundary towards transport processes in these ceramics. The UV–visible spectrum reveals that the synthesized ceramics, Al 0.70 Si 0.30 O, Al 0.73 Si 0.27 O, and Al 0.75 Si 0.25 O have a wide-band-gap of the order of 3.45 eV, 3.42 eV, and 3.39 eV respectively. These ceramics can be preferably used as electronic substrates, packaging material for high-frequency circuits, and infrared transmitting window materials.

Structural and dielectric properties of NaIO4 - Complexed PEO/PVP blended solid polymer electrolytes

H.K. Koduru,L. Marino,F. Scarpelli,A.G. Petrov,Y.G. Marinov,G.B. Hadjichristov,M.T. Iliev,N. Scaramuzza 한국물리학회 2017 Current Applied Physics Vol.17 No.11

Poly (ethylene oxide) (PEO)/Polyvinyl pyrrolidone (PVP) blended solid polymer electrolytes complexed with NaIO4 salt at different weight percentage ratios were prepared using solution casting technique. Effect of salt complexation on structural properties of pure blend (PEO/PVP) electrolyte was investigated by X-ray diffraction (XRD), Raman spectroscopy and Scanning electron microscopic (SEM) studies. Modifications in glass transition temperature and thermal stability of the blend electrolytes were measured by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) studies. The determined refractive index values from optical absorption spectra were found to increase with the increase of salt concentration. Impedance measurements were made in the frequency range of 0.1 Hz e1 MHz to explore dielectric response and ion dynamics of the blend electrolytes as a function of NaIO4 salt concentration. The PEO/PVP blend complexed with 10 wt% of NaIO4 salt was demonstrated higher room temperature conductivity of 1.56 107 S/cm. The temperature dependence of DC conductivity of blend electrolytes was followed the Arrhenius behaviour. Determined diffusion coefficients (DNaþ) using Trukhan model and estimated mobility (m) values of sodium ions were increased with increase of salt concentration. To get the further insights into the ion dynamics, the complex dielectric permittivity has been modeled with HavriliakeNegami function.

실험적 부자 시신경병증에서 Methylprednisolone의 효능

신재필,이상희,서형덕,김인택 경북대학교 병원 1998 경북대학교병원의학연구소논문집 Vol.2 No.1

동물실험에서 aconite 또는 aconitine은 신경계통에 독성을 나타낸다고 이미 알려져 있다. 그러한 독성은 시유발전위와 병리조직에서 탈수초증으로 나타난다. 저자들은 실험적으로 aconite을 주입하여 탈수초신경증을 일으킨 후 고용량이 methylprednisolone(MP)투여가 효능이 있는지를 알아보고자 하였다. Aconite를 복강내 주입하고 곧 이어 가토의 이연정맥으로 MP를 주입한 군과 aconite만을 주입한 군으로 나누었고 이들을 서로 비교하였다. 그리고 이 두 군을 정상군과도 비교하였다. 시유발전위에서 aconite를 주입후 MP를 투여한 군에서 aconite만을 주입한 군에 비하여 onset latency와 peak latency 그리고 진폭 모두에서 2주째에 통계학적으로 의미있게 회복되었으나 (p<0.05) 정상군과 비교하여 의미있는 차이를 나타내지 아니하였다. 그러나 정상군과 비교하여 1개월과 2개월에서 onset latency은 의미있게 지연되었고 (p<0.05) peak latency와 진폭은 다소 회복되었으나 정상군의 평균값에는 미치지 못하였다. 병리조직에서 MP으로 치료한 군과 aconite만을 주입한 군 모두에서 수초의 탈수초변화가 관찰되었으나 MP으로 치료한 군은 상대적으로 탈수초변화가 현저하지 아니하였다. 본 연구에서 실험적으로 가토에 aconite를 전신에 투여하여 시신경병증을 일으킨 후 고용량의 MP를 즉시 투여한 경우에 시신경의 기능을 정상상태까지 회복시키는데는 한계가 있으나 부분적으로 시신경의 기능을 회복시키는데 도움이 될 것으로 생각된다(한안지 37:1730~1740, 1996). Studies in animals indicate that aconitine or aconite has toxic effects in the visual system of a rabbit model. Such a toxic effects causes myelo-optic neuropathy in the visually evoked cortical potential(VECP) and histopathologic studies. Whether the administration of intravenous high-does of methyprednisolone(MP) in the myelo-optic neuropathy caused by aconitine(1.5㎖/㎏, equivalent to 0.7㎎/㎏ of aconitine) is experimentally effective remains uncertain. The group treated with MP(daily 30㎎/㎏×2 for 3 days followed by 15㎎/㎏ for 3 days) in addition to aconite was compared with the aconite alone group and the normal control group. In the MP treated group, increased recovery of onset latency, peak latency, and amplitude in VECP in comparision with the aconite alone group was recorded at 2 weeks(p<0.05). The MP treated group in comparision with the normal control group showed a significant delay in onset latency at 1 month and 2 months(p<0.05). But, the amplitude in both the MP treated group and the aconite alone group increased at 2 months and did not show a significant difference in comparision with the normal group(p<0.05). In histopathologic study, pathologic findings of myelin sheath in the MP treated group were less severe than in the aconite alone group generally. The true benefit of high-does MP was at least clear within 2 weeks. The authors conclude that treatment with intravenous high-does MP immediate after aconite injection may have some beneficial effects in recovery of neurologic function although such a treatment do no have the definite recovery in aconite induced myelo-optic neuropathy(J Korean Ophthalmol Soc 37:1730~1740, 1996).

정상안압녹내장에서 시간에 따른 망막신경섬유층 두께변화와 시야변화의 비교분석

이원혁,성미선,신준우,이주화.Won Hyuk Lee. MD. Mi Sun Sung. MD. Jun Woo Shin. MD. Joo Hwa Lee. MD 대한안과학회 2010 대한안과학회지 Vol.51 No.12

Purpose: To evaluate longitudinal changes in retinal nerve fiber layer thickness (RNFL) and visual field in patients with normal tension glaucoma (NTG). Methods: Thirty eyes of 30 NTG patients and 30 eyes of 30 normal control subjects were enrolled in the present study. RNFL thickness was measured using optical coherence tomography (OCT), and visual field tests were performed using a Humphrey visual field analyzer at baseline and 23.3 ± 15.3 months later. Changes in RNFL thickness at each clock-hour segment and visual field sensitivities were analyzed. The rates of change in RNFL thickness were also calculated. Results: Significant differences in RNFL thickness were observed between NTG patients and normal control subjects at the 5, 6, 7 and 12 o’clock positions at baseline (p < 0.001). At follow-up, the RNFL thickness change was not significant for normal control subjects, although it was significant for NTG patients at the 4, 5, 6, 7, 11 and 12 o'clock positions (p < 0.001). Visual field parameters did not change significantly in the normal control subjects or NTG patients. The reduction rates of RNFL thickness were 0.38 μm/month for the NTG patients and 0.11 μm/month for the normal control group, displaying a 3.5-fold faster reduction rate for NTG patients. Conclusions: The NTG group showed greater reductions in RNFL thickness in the upper and lower sectors over time; however, the visual field parameters did not change significantly. The results suggest that progression of glaucoma can be detected in an earlier stage using OCT than can be detected using a visual field test. J Korean Ophthalmol Soc 2010;51(12):1606-1613

한국 성인의 시신경염

강태신,이우혁,이연희 대한안과학회 2018 대한안과학회지 Vol.59 No.1

Purpose: The aim of the study was to describe the clinical features and characteristics of optic neuritis patients compared with those of patients enrolled in the Optic Neuritis Treatment Trial (ONTT). Methods: We retrospectively included consecutive patients diagnosed with optic neuritis between 2006 and 2015. The inclusion criteria were the same as those of the ONTT; an acute or subacute unilateral visual symptom ≤8 days in duration, a relative afferent pupillary defect, and a visual field defect in the affected eye. Results: The 41 patients (14 females, 27 males) were of mean age 32.7 years. The incidence of papilledema was 58.5%, thus higher than that of ONTT patients (p = 0.004), and the incidence of ocular pain was 75.6%, lower than that of ONTT patients (p = 0.002). Six months after intravenous methylprednisolone therapy, 29 of 32 eyes (90.6%) recovered visual acuity of ≥1.0 or better, and only one eye exhibited poor visual acuity (≤0.5). Orbital magnetic resonance imaging (MRI) was performed on 34 patients, and most (91.2%) exhibited optic nerve enhancement. The three patients who did not exhibit enhancement reported no pain. Conclusions: The clinical features of Korean optic neuritis patients differed from those of patients of the ONTT. Most patients exhibited optic nerve MRI enhancement associated with ocular pain. If enhancement of the optic nerve is lacking, diseases other than optic neuritis should be suspected because most optic nerves with neuritis exhibit enhancement on MRI. 목적: 한국 성인의 시신경염 임상양상과 특성을 Optic Neuritis Treatment Trial (ONTT) 연구와 비교하여 밝히고자 하였다. 대상과 방법: 2006년부터 2015년까지 단안 시신경염으로 진단된 18세에서 46세 사이의 환자를 대상으로 의무기록을 후향적으로 검토하였다. 포함기준은 ONTT와 같이 단안에서 급성 또는 아급성의 시력저하와 상대구심동공운동장애 양성이면서, 증상 발생 8일 이내에 내원하여 자동시야검사에서 시야결손을 보이는 환자를 대상으로 하였다. 결과: 총 41명이 포함되었고, 평균 연령은 32.7세, 남자의 비율이 65.9%였다. 시신경유두부종이 있었던 환자의 비율은 58.5%로 ONTT 의 보고보다 높았고(p=0.004), 안구운동 시 통증이 있었던 환자는 75.6%로 ONTT 보고보다 낮았다(p=0.002). 고용량 정맥 스테로이드 치료 6개월 후 최종적으로 1.0 이상의 시력을 보인 환자는 90.6%였고, 0.5 이하의 나쁜 시력을 보인 환자는 3.1%였다. 34명에서 안와 자기공명영상을 촬영하였고 91.2%에서 시신경의 조영 증강을 보였다. 조영 증강이 되지 않은 3명은 모두 통증을 호소하지 않았다. 결론: 한국 성인의 시신경염은 ONTT 연구와 임상양상이 다르다. 시신경염은 대부분 자기공명영상에서 시신경의 조영 증강을 보이므로 조영 증강이 없으면 다른 질환을 의심해 볼 필요가 있다.

Enhanced optical, visible light catalytic and electrochemical properties of Au@TiO2 nanocomposites

Mohammad Mansoob Khan,조무환,Sajid Ali Ansari,이진태 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.6

Au@TiO2 nanocomposites and pure TiO2 were successfully used to know the effect of Au on TiO2 and their comparative optical, visible light catalytic and electrochemical activities were investigated. Optical parameters such as band gap energy (Eg = 2.4 eV), absorption coefficient (a), refractive index (n) and dielectric constants (s) have been determined using different methods. Visible light (l = 590 nm)catalytic activity of Au@TiO2 nanocomposites was performed for reducing methyl orange (MO) under visible light irradiation. CV, EIS and DPV studies demonstrate that Au@TiO2 nanocomposites exhibit redox behavior, charged its surface by accumulating electrons, store and release the electrons.

Growth and characterization of semi organic nonlinear optical L-Valine Ferric Chloride single crystal by solution growth technique

P. Geetha,S. Krishnan,R.K. Natarajan,V. Chithambaram 한국물리학회 2015 Current Applied Physics Vol.15 No.3

L-Valine Ferric Chloride single crystal is a new semi organic nonlinear optical material. It has been grown from a mixture of aqueous solutions of L-Valine and Ferric Chloride by slow evaporation solution growth technique at room temperature for the first time. Single crystal XRD analysis revealed that the crystal system belongs to Cubic P with cell parameters are a = 24.38 Å, b = 24.38 Å, c = 24.38 Å and volume is 14,485 Å3. The UV spectrum shows existence of wide transparency window suitable for optoelectronic applications. Thermal stability and melting temperature of the as grown crystal was identified from TGDTA analysis. Spectroscopic studies have been carried out for analyzing the presence of functional groups, thermal stability and phase transition of the grown crystal. The dielectric loss and the dielectric constant of the crystals were measured as a function of frequency. Photoluminescence study was carried out for grown crystals and the maximum emission occurs has good optical transmission in the entire visible region. Second harmonic generation (SHG) conversion efficiency has been estimated.

Ground state opto-electronic and thermoelectric response of cubic XSnO3 (X = Ba, Sr) compounds

M. Bilal Saddique,Muhammad Rashid,Adnan Afzal,Shahid M. Ramay,Farooq Aziz,Asif Mahmood 한국물리학회 2017 Current Applied Physics Vol.17 No.8

The density functional has been implemented to deliberate the cubic perovskite XSnO3 (X ¼ Ba, Sr) for their elastic, electronic, optical as well as thermoelectric characteristic. The XSnO3 (X ¼ Ba, Sr) illustrates good pact of lattice parameter for these iso-structural compounds having cubic perovskite structure. The generalized gradient approximation based on the exchange-correlation functional is applied for computing structural and mechanical characteristic, whereas the electronic, optical and thermoelectric properties have been studied by the functional suggested by Tran and Blaha that is termed as of modified Becke-Johnson (mBJ) functional. The thermodynamics stability is recognized through the expression of enthalpies of formation, which is further verified from the calculated structural properties of cubic perovskite XSnO3 (X ¼ Ba, Sr). Moreover, various elastic parameters such has bulk modules B, Cij, shear modulus G, Young's modulus Y, anisotropy factor, B/G ratio and Poisson's ratio n have also been reported. It has been observed by band structure computation that the studied compounds exhibit an indirect band gap between the unoccupied Ba/Sr 6s/5s and the occupied O 2p orbitals. Detailed study of optical properties is presented under the incident photon energy upto 28 eV. Our computed static dielectric constant ε2(0) and refractive index n(0) are comparable with other theoretical and experimental values. Thermoelectric properties are presented in terms of computed Seebeck coefficient, electrical and thermal conductivities and their variation with the rise in temperature suggest that the studied compounds may find applications in the construction of various thermo-electric devices.