• 한국환경농학회지
• /
• 제30권3호
• /
• pp.323-329
• /
• 2011

BACKGROUND: The conazoles, difenoconazole, diniconazole, hexaconazole, penconazole and tetraconazole are a large class of synthetic fungicides used extensively for foliage and seed treatments in agricultural crops. The extensive use of conazoles has brought concerns on the potentiality of environmental contamination and toxicity. Thus studies on the development of methods for monitoring the conazoles are required. METHODS AND RESULTS: A modified quick, easy, effective, rugged and safe (QuEChERS) method was involved in sample preparation. Quadrapole time of flight mass spectrometer (Q-TOF MS) in electron spray ionization (ESI) mode was employed to determine conazoles in garlic samples. The limit of detection (LOD) and limit of quantification (LOQ) of conazoles by Q-TOF-MS ranged from 0.001 to 0.002 mg/L and 0.002 to 0.005 mg/L, respectively. Q-TOF-MS analysis exhibited less than 2.6 ppm error of accurate mass measurements for the detection of conazoles spiked at 0.05 mg/L in garlic matrix. Recovery values of conazoles fortified in garlic samples at 0.02, 0.05 and 0.1 mg/L were between 79.2 and 106.2% with a maximum 11.8% of standard deviation. No detectable conazoles were found in the domestic market samples by using the Q-TOF-MS method. CONCLUSION(s): High degree of confirmation for conazoles by accurate mass measurements demonstrated that Q-TOF-MS analysis combined with a QuEChERS method may be applicable to simultaneous determination of conazoles in garlic samples.

• Investigative Magnetic Resonance Imaging
• /
• 제25권4호
• /
• pp.323-331
• /
• 2021

Purpose: To investigate the diagnostic criteria of T1-weighted imaging (T1W) and time-of-flight (TOF) imaging for detecting intraplaque hemorrhage (IPH) of a vertebrobasilar artery (VBA) compared with simultaneous non-contrast angiography and intraplaque hemorrhage (SNAP) imaging. Materials and Methods: Eighty-seven patients with VBA atherosclerosis who underwent high resolution MR imaging for evaluation of VBA plaque were reviewed. The presence and location of VBA plaque and IPH on SNAP were determined. The signal intensity (SI) of the VBA plaque on T1W and TOF imaging was manually measured and the SI ratio against adjacent muscles was calculated. The receiver-operating characteristic (ROC) curve was used to compare the diagnostic accuracy for detecting VBA IPH. Results: Of 87 patients, 67 had IPH and 20 had no IPH on SNAP. The SI ratio between VBA IPH and temporalis muscle on T1W was significantly higher than that in the no-IPH group (235.9 ± 16.8 vs. 120.0 ± 5.1, P < 0.001). The SI ratio between IPH and temporalis muscle on TOF was also significantly higher than that in the no-IPH group (236.8 ± 13.3 vs. 112.8 ± 7.4, P < 0.001). Diagnostic efficacies of SI ratios on TOF and TIW were excellent (AUC: 0.976 on TOF and 0.964 on T1W; cutoff value: 136.7% for TOF imaging and 135.1% for T1W imaging). Conclusion: Compared with SNAP, cutoff levels of the SI ratio between VBA plaque and temporalis muscle on T1W and TOF imaging for detecting IPH were approximately 1.35 times.

• 한국근적외분광분석학회:학술대회논문집
• /
• 한국근적외분광분석학회 2001년도 NIR-2001
• /
• pp.1627-1627
• /
• 2001

In this study, a newly constructed optical measurement system, whose main components were a parametric tunable laser and a near infrared photoelectric multiplier, was applied to detection of the information for the inside of Satsuma mandarin using time-of-flight near infrared spectroscopy (TOF-NIRS). The combined effects on the time resolved profile of sample diameter, sugar content, the wavelength of the laser beam, and the detection position of transmitted light were investigated in detail. The samples used were Satsuma mandarin (Citrus unshu $M^{ARC}$.) (location: Wakayama, Japan) having the diameters of 50-84 mm. The sugar content measured by a refractometer varied from 9.9 to 16.3 Brix%. Equator of sample was irradiated vertically with the pulsed laser, and transmitted output power was measured on the restricted position of the equator using the optical fiber cable. The sampling time and the number of averaging the output power were 100 ns and 100 times, respectively. The variation of the attenuance of peak maxima At, the time delay of peak maxima t and the variation of full width at half maximum w were strongly dependent on the detection position and the wavelength of the laser beam. At, t and w increased gradually as the sample diameter increased to be much absorbed and vigorously scattered. On the other hand, each optical parameter had a tendency to increase as the sugar content increased. Such behavior was remarkable when the transmitted light was detected at the side face of a sample. When we apply TOF-NIRS to detection of the information for the inside of fruit with high moisture content like Satsuma mandarin, it is very important to give attention to the difference in the scattered light within tissues and the semi-straightly propagated light. Furthermore, we tried to express the resulting phenomena by using a model samples composed of water, sucrose, and milk. The variation of the time resolved profile is strongly governed by the combination of the light absorption component, scattering medium, and refractive index.

• 한국근적외분광분석학회:학술대회논문집
• /
• 한국근적외분광분석학회 2001년도 NIR-2001
• /
• pp.1626-1626
• /
• 2001

In this study, a newly constructed optical measurement system, whose main components were a parametric tunable laser and a near infrared photoelectric multiplier, was applied to detection of the information for the inside of Satsuma mandarin using time-of-flight near infrared spectroscopy (TOF-NIRS). The combined effects on the time resolved profile of sample diameter, sugar content, the wavelength of the laser beam, and the detection position of transmitted light were investigated in detail. The samples used were Satsuma mandarin (Citrus unshu $M_{ARC}$.) (location: Wakayama, Japan) having the diameters of 50-84 mm. The sugar content measured by a refractometer varied from 9.9 to 16.3 Brix%. Equator of sample was irradiated vertically with the pulsed laser, and transmitted output power was measured on the restricted position of the equator using the optical fiber cable. The sampling time and the number of averaging the output power were 100 ns and 100 times, respectively. The variation of the attenuance of peak maxima At, the time delay of peak maxima $\Delta$t and the variation of full width at half maximum Δw were strongly dependent on the detection position and the wavelength of the laser beam. At, $\Delta$t and $\Delta$w increased gradually as the sample diameter increased to be much absorbed and vigorously scattered. On the other hand, each optical parameter had a tendency to increase as the sugar content increased. Such behavior was remarkable when the transmitted light was detected at the side face of a sample. When we apply TOF-NIRS to detection of the information for the inside of fruit with high moisture content like Satsuma mandarin, it is very important to give attention to the difference in the scattered light within tissues and the semi-straightly propagated light. Furthermore, we tried to express the resulting phenomena by using a model samples composed of water, sucrose, and milk. The variation of the time resolved profile is strongly governed by the combination of the light absorption component, scattering medium, and refractive index.

• 분석과학
• /
• 제18권6호
• /
• pp.483-490
• /
• 2005

TOF 비행시간을 이용한 에어로졸 질량분석기에서 질량분석기의 분해능은 발생하는 이온의 초기에너지와 이온이 움직이는 진행방향에 따라 달라진다. 고출력 펄스형 레이저에 의하여 에어로졸로부터 용발되어 이온화된 원소들은 다른 속도로 사방으로 퍼져 나가게 되어 분해능 저하를 초래하는데 이를 방지하기 위해서 1차 가속된 이온들을 서로 다른 에너지로 후집속하여 같은 시간에 이온센서에 도달하도록 하는 장치에 대하여 연구를 수행하였다. 후집속 전위를 $90^{\circ}$ 방향으로 진행하는 이온을 중심으로 서로 다른 방향으로 걸어 줌으로써 TOF 영역을 지나 센서로 도입되는 이온의 도착 시간이 크게 개선되었음을 알 수 있었으며, 이를 실증하기 위하여 레이저 유도 이온을 만들고 후집속 장치를 구성하여 최적의 시간지연시간 및 전압 조건을 도출하여 그 성능을 증가시켰다.

• 공업화학
• /
• 제28권3호
• /
• pp.263-271
• /
• 2017

최근에, 질량분석기술의 폴리머 분석에의 응용은 MALDI-TOF MS 개발 이후 급속도로 발전하였다. 이 리뷰 논문은 현재까지 연구된 MALDI-TOF MS의 폴리머 특성분석에의 응용에 관한 최신 논문을 정리하였다. MALDI-TOF MS는 바이오 폴리머와, 합성 폴리머의 평균분자량 분석, 폴리머의 시퀀스 분석을 통한 구조의 해석, 모노머의 조성분석에까지 이용되고 있다. 엔드그룹의 특성과 농도를 분석하는 연구도 많이 진행되었고, 복잡한 폴리머의 분자량의 분석에는 SEC와 MALDI-TOF MS를 연결한 분석법을 추천한다. MALDI에 tandem MS를 결합한 분석기술이나, 이온 모빌리티를 응용한 질량분석기, TOF-SIMS, MALDI-TOF-Imaging 기술도 급격히 발전하고 있으며, 이의 폴리머 특성분석에의 응용은 별도의 분리기술이 필요 없어 앞으로 더 많이 이용될 것으로 생각된다. 분자량, 시퀀스, 그리고 모노머의 조성을 정확하게 계산해주는 소프트웨어와 고분자량(> 100 kDa)의 분석을 가능하게 해주는 기술이 개발된다면, 폴리머를 연구하는 과학자들에게 MALDI-TOF MS의 이용은 문제점을 해결하고, 목적하는 폴리머를 합성하는 데 중요한 수단이 될 것이다.

• Investigative Magnetic Resonance Imaging
• /
• 제22권2호
• /
• pp.94-101
• /
• 2018

Purpose: To determine the value of the appearance of the high signal intensity halo sign for detecting carotid intraplaque hemorrhage (IPH) on maximum intensity projection (MIP) of time-of-flight (TOF) MR angiography (MRA), based on high signal intensity on magnetization-prepared rapid acquisition with gradient-echo (MPRAGE) sequencing. Materials and Methods: A total of 78 carotid arteries in 65 patients with magnetization-prepared rapid acquisition gradient-echo (MPRAGE) positive on carotid plaque MR imaging were included in this study. High-resolution MR imaging was performed on a 3.0-T scanner prior to carotid endarterectomy or carotid artery stenting. Fast spin-echo T1- and T2-weighted axial imaging, TOF, and MPRAGE sequences were obtained. Carotid plaques with high signal intensity on MPRAGE > 200% that of adjacent muscle on at least two consecutive slices were defined as showing IPH. Halo sign of high signal intensity around the carotid artery was found on MIP from TOF MRA. Continuous and categorical variables were compared among groups using the Mann-Whitney test and Fisher's exact tests. Results: Of these 78 carotid arteries, 53 appeared as a halo sign on the TOF MRA. The total IPH volume of patients with a positive halo sign was significantly higher than that of patients without a halo sign ($75.0{\pm}86.8$ vs. $16.3{\pm}18.2$, P = 0.001). The maximum IPH axial wall area in patients with a positive halo sign was significantly higher than that of patients without a halo sign ($11.3{\pm}9.9$ vs. $3.7{\pm}3.6$, P = 0.000). Conclusion: High signal intensity halo of IPH on MIP of TOF MRA is associated with total volume and maximal axial wall area of IPH.

• Korean Journal of Radiology
• /
• 제23권2호
• /
• pp.246-255
• /
• 2022

Objective: To determine the usefulness of Silent MR angiography (MRA) for evaluating intracranial aneurysms treated with stent-assisted coil embolization. Materials and Methods: Ninety-nine patients (101 aneurysms) treated with stent-assisted coil embolization (Neuroform atlas, 71 cases; Enterprise, 17; LVIS Jr, 9; and Solitaire AB, 4 cases) underwent time-of-flight (TOF) MRA and Silent MRA in the same session using a 3T MRI system within 24 hours of embolization. Two radiologists independently interpreted both MRA images retrospectively and rated the image quality using a 5-point Likert scale. The image quality and diagnostic accuracy of the two modalities in the detection of aneurysm occlusion were further compared based on the stent design and the site of aneurysm. Results: The average image quality scores of the Silent MRA and TOF MRA were 4.38 ± 0.83 and 2.78 ± 1.04, respectively (p < 0.001), with an almost perfect interobserver agreement. Silent MRA had a significantly higher image quality score than TOF MRA at the distal internal carotid artery (n = 57, 4.25 ± 0.91 vs. 3.05 ± 1.16, p < 0.001), middle cerebral artery (n = 21, 4.57 ± 0.75 vs. 2.19 ± 0.68, p < 0.001), anterior cerebral artery (n = 13, 4.54 ± 0.66 vs. 2.46 ± 0.66, p < 0.001), and posterior circulation artery (n = 10, 4.50 ± 0.71 vs. 2.90 ± 0.74, p = 0.013). Silent MRA had superior image quality score to TOF MRA in the stented arteries when using Neuroform atlas (4.66 ± 0.53 vs. 3.21 ± 0.84, p < 0.001), Enterprise (3.29 ± 1.59 vs. 1.59 ± 0.51, p = 0.003), LVIS Jr (4.33 ± 1.89 vs. 1.89 ± 0.78, p = 0.033), and Solitaire AB stents (4.00 ± 2.25 vs. 2.25 ± 0.96, p = 0.356). The interpretation of the status of aneurysm occlusion exhibited significantly higher sensitivity with Silent MRA than with TOF MRA when using the Neuroform Atlas stent (96.4% vs. 14.3%, respectively, p < 0.001) and LVIS Jr stent (100% vs. 20%, respectively, p = 0.046). Conclusion: Silent MRA can be useful to evaluate aneurysms treated with stent-assisted coil embolization, regardless of the aneurysm location and type of stent used.

• 대한전자공학회논문지SP
• /
• 제37권1호
• /
• pp.27-36
• /
• 2000

본 연구에서는 초음파와 tomography 기법을 기반으로 콘크리트 구조물의 비파괴 시험에 대한 방법론을 정립하고 검증하였다 일반적인 X-ray tomography에서는 물체를 통과하는 파동의 감쇠(attenuation) 데이터에 기초를 두고있는 반면에, 본 연구에서는 time-of-flight(TOF) 데이터를 사용하여 매질의 굴절률(refractive index)을 포괄적으로 표현하는 단층영상을 복원한다 X-ray tomography에서는 측정된 감쇠 데이터를 영상복원(Image reconstruction) 알고리즘에 의해서 처리하며, 파동의 굴절은 고려할 필요가 없다 그러나 초음파는 매질(medium)의 굴절률(refractive index)에 따라 초음파의 경보가 변경되므로 초음파 tomography에서는 초음파 경로의 연산이 선행되어야만 단층영상을 복원할 수 있게 된다 초음파 정보의 연산은 가하광학(Geometrical Optic)에서 사용되는 굴절률과 경로의 관계에 기초를 둔다 영상 복원은 대수학적 접근 방법인 ART (algebraic reconstruction technique) 또는 SIRT(simultaneous iterative reconstruction technique)를 기초로 연산된 초음파의 경로를 따라 선적분한 TOF 값과 측정된 TOF 값의 차이를 기반으로 수행된다 실제 구현에서는 초음파가 직진한다는 가정하에 영상을 복원하고, 이를 기반으로 초음파의 경로를 연산하였다 본 논문에서는 이들 두 과정(경로연산 및 영상복원)의 반복연산을 통하여 영상을 복원하였다. 세안하는 알고리즘을 모의실험으로 평가하였고, 실제 콘크리트 구조물에 적용하여 본 방법론의 무한한 가능성을 입증하였다.

• Biomolecules & Therapeutics
• /
• 제21권6호
• /
• pp.470-475
• /
• 2013

Ultraviolet (UV) radiation is a major environmental factor that leads to acute and chronic reactions in the human skin. UV exposure induces wrinkle formation, DNA damage, and generation of reactive oxygen species (ROS). Most mechanistic studies of skin physiology and pharmacology related with UV-irradiated skin have focused on proteins and their related gene expression or single-targeted small molecules. The present study identified and analyzed the alteration of skin metabolites following UVB irradiation and topical retinyl palmitate (RP, 5%) treatment in hairless mice using direct analysis in real time (DART) time-of-flight mass spectrometry (TOF-MS) with multivariate analysis. Under the negative ion mode, the DART ion source successfully ionized various fatty acids including palmitoleic and linolenic acid. From DART-TOF-MS fingerprints measured in positive mode, the prominent dehydrated ion peak (m/z: 369, M+H-$H_2O$) of cholesterol was characterized in all three groups. In positive mode, the discrimination among three groups was much clearer than that in negative mode by using multivariate analysis of orthogonal partial-least squares-discriminant analysis (OPLS-DA). DART-TOF-MS can ionize various small organic molecules in living tissues and is an efficient alternative analytical tool for acquiring full chemical fingerprints from living tissues without requiring sample preparation. DART-MS measurement of skin tissue with multivariate analysis proved to be a powerful method to discriminate between experimental groups and to find biomarkers for various experiment models in skin dermatological research.