1
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Minami M, Nakata S, Uchimura T. Sample preparation conditions for the real-time measurement of W/O emulsions by resonance-enhanced multiphoton ionization time-of-flight mass spectrometry. ANAL SCI 2024; 40:573-577. [PMID: 38194211 PMCID: PMC10894760 DOI: 10.1007/s44211-023-00486-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Accepted: 11/29/2023] [Indexed: 01/10/2024]
Abstract
Analysis of an emulsion in its original dispersed condition is quite important for quality assessment and quality control. In the present study, the practical experimental conditions of the real-time measurement of a water-in-oil (W/O) emulsion were examined via resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS). A W/O emulsion was prepared using cyclohexane as the oil phase with toluene as an analyte species. A time profile of the peak area for toluene was constructed based on the mass spectra. Normally, the negative spikes of a base signal are detected in a time profile when analyte molecules are dispersed in an oil phase. In this case, however, the positive spikes were unexpectedly detected rather than the negative ones. Though several factors could be relevant for the occurrence of the positive spikes, these spikes could have been suppressed by the addition of a small amount of n-alkane when the oil phase was prepared in the present study. The practical experimental conditions for the analysis of a W/O emulsion in real-time revealed that this method would be applicable to the analysis of an oil-in-water-in-oil (O/W/O) emulsion where the outer phase is also an oil phase.
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Affiliation(s)
- Minori Minami
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui, 910-8507, Japan
| | - Shion Nakata
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui, 910-8507, Japan
| | - Tomohiro Uchimura
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui, 910-8507, Japan.
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2
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Munekata R, Uchimura T, Araki H, Kanai A, Tanaka K, Okamoto T, Akaki Y. Optimization of Sulfide Annealing Conditions for Ag 8SnS 6 Thin Films. Materials (Basel) 2023; 16:6289. [PMID: 37763566 PMCID: PMC10533031 DOI: 10.3390/ma16186289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 09/04/2023] [Accepted: 09/08/2023] [Indexed: 09/29/2023]
Abstract
Ag8SnS6 (ATS) has been reported to have a band gap of 1.33 eV and is expected to be a suitable material for the light-absorbing layers of compound thin-film solar cells. However, studies on solar cells that use ATS are currently lacking. The objective of this study is to obtain high-quality ATS thin films for the realization of compound thin-film solar cells using vacuum deposition and sulfide annealing. First, glass/SnS/Ag stacked precursors are prepared by vacuum deposition. Subsequently, they are converted to the ATS phase via sulfide annealing, and various process conditions, namely, annealing time, annealing temperature, and number of steps, are studied. By setting the heat treatment temperature at 550 °C and the heat treatment time at 60 min, a high-quality ATS thin film could be obtained. Multi-step heat treatment also produces thin films with nearly no segregation or voids.
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Affiliation(s)
- Ryuki Munekata
- National Institute of Technology (KOSEN), Miyakonojo College, Miyakonojo 885-8567, Japan;
| | - Tomohiro Uchimura
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai 980-8576, Japan;
| | - Hideaki Araki
- National Institute of Technology (KOSEN), Nagaoka College, Nagaoka 940-8532, Japan;
| | - Ayaka Kanai
- Department of Electrical, Electronics and Information Engineering
Electronic Device and Light Wave Control Engineering Group, Nagaoka University of Technology, Nagaoka 940-2218, Japan (T.O.)
| | - Kunihiko Tanaka
- Department of Electrical, Electronics and Information Engineering
Electronic Device and Light Wave Control Engineering Group, Nagaoka University of Technology, Nagaoka 940-2218, Japan (T.O.)
| | - Tomoichiro Okamoto
- Department of Electrical, Electronics and Information Engineering
Electronic Device and Light Wave Control Engineering Group, Nagaoka University of Technology, Nagaoka 940-2218, Japan (T.O.)
| | - Yoji Akaki
- National Institute of Technology (KOSEN), Miyakonojo College, Miyakonojo 885-8567, Japan;
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3
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Yoon JY, Zhang P, Chou CT, Takeuchi Y, Uchimura T, Hou JT, Han J, Kanai S, Ohno H, Fukami S, Liu L. Handedness anomaly in a non-collinear antiferromagnet under spin-orbit torque. Nat Mater 2023; 22:1106-1113. [PMID: 37537356 DOI: 10.1038/s41563-023-01620-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 06/23/2023] [Indexed: 08/05/2023]
Abstract
Non-collinear antiferromagnets are an emerging family of spintronic materials because they not only possess the general advantages of antiferromagnets but also enable more advanced functionalities. Recently, in an intriguing non-collinear antiferromagnet Mn3Sn, where the octupole moment is defined as the collective magnetic order parameter, spin-orbit torque (SOT) switching has been achieved in seemingly the same protocol as in ferromagnets. Nevertheless, it is fundamentally important to explore the unknown octupole moment dynamics and contrast it with the magnetization vector of ferromagnets. Here we report a handedness anomaly in the SOT-driven dynamics of Mn3Sn: when spin current is injected, the octupole moment rotates in the opposite direction to the individual moments, leading to a SOT switching polarity distinct from ferromagnets. By using second-harmonic and d.c. magnetometry, we track the SOT effect onto the octupole moment during its rotation and reveal that the handedness anomaly stems from the interactions between the injected spin and the unique chiral-spin structure of Mn3Sn. We further establish the torque balancing equation of the magnetic octupole moment and quantify the SOT efficiency. Our finding provides a guideline for understanding and implementing the electrical manipulation of non-collinear antiferromagnets, which in nature differs from the well-established collinear magnets.
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Affiliation(s)
- Ju-Young Yoon
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
- Graduate School of Engineering, Tohoku University, Sendai, Japan
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Pengxiang Zhang
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Chung-Tao Chou
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Yutaro Takeuchi
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, Japan
| | - Tomohiro Uchimura
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
- Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Justin T Hou
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jiahao Han
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan.
| | - Shun Kanai
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
- Graduate School of Engineering, Tohoku University, Sendai, Japan
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, Japan
- Center for Science and Innovation in Spintronics, Tohoku University, Sendai, Japan
- Division for the Establishment of Frontier Sciences of Organization for Advanced Studies, Tohoku University, Sendai, Japan
| | - Hideo Ohno
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
- Graduate School of Engineering, Tohoku University, Sendai, Japan
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, Japan
- Center for Science and Innovation in Spintronics, Tohoku University, Sendai, Japan
- Center for Innovative Integrated Electronic Systems, Tohoku University, Sendai, Japan
| | - Shunsuke Fukami
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan.
- Graduate School of Engineering, Tohoku University, Sendai, Japan.
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, Japan.
- Center for Science and Innovation in Spintronics, Tohoku University, Sendai, Japan.
- Center for Innovative Integrated Electronic Systems, Tohoku University, Sendai, Japan.
- Inamori Research Institute for Science, Kyoto, Japan.
| | - Luqiao Liu
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA.
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Yamashita K, Kato N, Sakakibara K, Seguchi A, Kobayashi A, Miyagawa S, Uchimura T. Characterization of Cooked Nonglutinous Rice Cultivars Based on Flavor Volatiles and Their Change during Storage. ACS Omega 2023; 8:14823-14829. [PMID: 37125109 PMCID: PMC10134245 DOI: 10.1021/acsomega.3c01276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Accepted: 04/04/2023] [Indexed: 05/03/2023]
Abstract
Characterizing fleshly cooked rice cultivars according to the volatile aroma compounds helps consumers select a favorite and is useful for the development of new cultivars that will have a pleasant aroma. In the present study, six Japanese nonglutinous cultivars, which were freshly harvested in 2021, were characterized based on their flavor volatiles after being freshly cooked. In order to extract the volatile compounds just after cooking, the vaporized compounds were extracted for 5 min using a solid-phase microextraction (SPME) fiber and were measured via gas chromatography/mass spectrometry (GC/MS). Multiple comparison tests statistically detected four volatile aroma compounds: 2-pentylfuran, nonanal, 4-vinylphenol, and indole. From among the six rice cultivars tested, the proportions of the latter two compounds showed significant differences, and in principal component analysis of cooked rice, these two best characterized freshly harvested and freshly cooked Japanese nonglutinous rice cultivars; indole was indicative of Nipponbare, and 4-vinylphenol was indicative of Koshihikari and Ichihomare. In the present study, changes in the volatile aroma compounds of the freshly cooked rice cultivars were found to slightly differentiate according to storage times: 2-pentylfuran tended to increase, nonanal first increased and then decreased, and 4-vinylphenol and indole either remained almost unchanged or were only slightly decreased during storage. Therefore, establishing the differences in rice cultivar types revealed that the characteristics of the flavor volatiles of freshly cooked rice after long-term storage significantly depend on how the rice cultivar is stored.
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Affiliation(s)
- Keishi Yamashita
- Department
of Materials Science and Engineering, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
| | - Nanako Kato
- Department
of Materials Science and Engineering, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
| | - Kento Sakakibara
- Department
of Materials Science and Engineering, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
| | - Aki Seguchi
- Department
of Materials Science and Biotechnology, School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
| | - Asako Kobayashi
- Fukui
Agricultural Experiment Station, 52-21 Ryomachi, Fukui 918-8215, Japan
| | - Shinobu Miyagawa
- Department
of Materials Science and Engineering, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
| | - Tomohiro Uchimura
- Department
of Materials Science and Engineering, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
- . Phone: +81-776-27-8610
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5
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Sugiyama T, Minami M, Uchimura T. Using Resonance-Enhanced Multiphoton Ionization Time-of-Flight Mass Spectrometry to Evaluate the Movement of a Constituent in a Multiple Emulsion. ACS Omega 2022; 7:2099-2104. [PMID: 35071898 PMCID: PMC8772314 DOI: 10.1021/acsomega.1c05599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 12/24/2021] [Indexed: 06/14/2023]
Abstract
Herein, we propose a method for evaluating the movement of a constituent in a multiple emulsion while maintaining its original dispersed condition. In this study, an oil-in-water-in-oil (O1/W/O2) emulsion was prepared using a two-step emulsification method with styrene as an analyte species in the inner phase (O1). The emulsion was measured using resonance-enhanced multiphoton ionization time-of-flight mass spectrometry without pretreatment such as centrifugation. From a series of obtained mass spectra, a time profile for the peak areas arising from styrene was constructed. When the emulsion was measured immediately following preparation, a time profile composed of a base, positive, and negative signals confirmed the presence of styrene in the O2, O1, and W phases, respectively. Moreover, while a small amount of styrene was present in the inner O1 phase, almost all of the styrene was found in the outer O2 phase. Furthermore, the results of the obtained time profile were converted into a box plot, and a method for the selection of the base, positive, and negative signals was tentatively determined. Then, the movement of styrene among the phases could be evaluated using the time courses of these signals; the time constant of the movement of styrene from an O1/W droplet to the O2 phase was calculated to be 0.8 h.
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Affiliation(s)
- Tomonobu Sugiyama
- Department
of Materials Science and Engineering, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
| | - Minori Minami
- Department
of Materials Science and Biotechnology, School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
| | - Tomohiro Uchimura
- Department
of Materials Science and Engineering, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
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6
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Takezawa H, Itadani K, Obata R, Sugiyama T, Uchimura T. Quantitative Evaluation of the Creaming of Emulsions via Resonance-Enhanced Multiphoton Ionization Time-of-Flight Mass Spectrometry. ANAL SCI 2021; 37:1453-1457. [PMID: 34629360 DOI: 10.2116/analsci.21p102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The creaming behavior of an oil-in-water (O/W) emulsion was quantitatively evaluated via resonance-enhanced multiphoton ionization time-of-flight mass spectrometry. Styrene O/W emulsions were prepared with initial styrene concentrations of 1 and 4 g/L, and the height at the center of the sample was monitored. A peak area of the molecular ion of styrene was set as the signal intensity, for which a time profile was constructed from a series of mass spectra. As a result, the averaged time profiles showed that the signal intensities increased once and then decreased with the onset of creaming. In addition, in order to fit an experimentally obtained time profile, a modified fit function was proposed. Based on the fit results, the ratios of the increases and decreases in signal intensities were different between the two emulsions-higher in the case of an O/W emulsion with a higher initial oil concentration. On the other hand, the duration of the enhancement of the signal intensity with the onset of creaming was independent of the initial oil concentration. The present method offers the possibility to quantitatively evaluate the creaming behavior of an emulsion without pretreatment, and, therefore, would be useful for confirming the stability and quality assurance of emulsions.
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Affiliation(s)
- Hideyuki Takezawa
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui
| | - Kengo Itadani
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui
| | - Ryosuke Obata
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui
| | - Tomonobu Sugiyama
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui
| | - Tomohiro Uchimura
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui
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7
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Takezawa H, Iwata M, Ueyama T, Uchimura T. Correction to "Using Resonance-Enhanced Multiphoton Ionization Time-of-Flight Mass Spectrometry to Quantitatively Analyze the Creaming of an Emulsion". ACS Omega 2021; 6:7966. [PMID: 33778308 PMCID: PMC7992137 DOI: 10.1021/acsomega.1c00843] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Indexed: 06/12/2023]
Abstract
[This corrects the article DOI: 10.1021/acsomega.9b02930.].
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8
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Sugiyama T, Iwata M, Ueyama T, Uchimura T. Characteristic Signal Behaviors for Water-in-Oil and Oil-in-Water Emulsions Measured by Resonance-Enhanced Multiphoton Ionization Time-of-Flight Mass Spectrometry. ACS Omega 2020; 5:31289-31294. [PMID: 33324839 PMCID: PMC7726925 DOI: 10.1021/acsomega.0c04734] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Accepted: 11/13/2020] [Indexed: 06/12/2023]
Abstract
Resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS) was used to study the characteristic signal behaviors obtained from two types of emulsions: water-in-oil (W/O) and oil-in-water (O/W). All emulsions were prepared using phase inversion emulsification, i.e., a solution for an aqueous phase was added dropwise to an oil phase with constant stirring to obtain an emulsion. Toluene served as a detection component. When using REMPI-TOFMS to measure an emulsion, a time profile for the target component can be constructed by plotting peak areas for the corresponding component on a series of mass spectra. In the case of a W/O emulsion at a water volume fraction (f w) of 0.005, the concentration of toluene was instantaneously decreased due to the existence of water droplets, and therefore, several negative spikes were detected on the time profile while establishing a baseline. In the case of a W/O emulsion at f w = 0.3, negative peaks consisting of several plots appeared on the time profile because of the formation of aggregates of water droplets while the emulsion was flowed through a capillary column for sample introduction. An O/W emulsion at f w = 0.995 was analyzed following phase inversion, and positive peaks were detected due to the aggregates of many oil droplets. In this manner, the direct mass analysis of emulsions before and after phase inversion was achieved, and the resultant signal inversion was confirmed via REMPI-TOFMS.
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Shinoda R, Takahashi K, Ichikawa S, Wakayama M, Kobayashi A, Miyagawa S, Uchimura T. Using SPME-GC/REMPI-TOFMS to Measure the Volatile Odor-Active Compounds in Freshly Cooked Rice. ACS Omega 2020; 5:20638-20642. [PMID: 32832817 PMCID: PMC7439695 DOI: 10.1021/acsomega.0c03037] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 07/23/2020] [Indexed: 05/17/2023]
Abstract
The volatile odor-active compounds of cooked rice were evaluated using a method that combined solid-phase microextraction (SPME) with gas chromatography-resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (GC/REMPI-TOFMS). An SPME fiber was held at the upper levels of the cooked rice and given an extraction time of 5 min. By using a nanosecond ultraviolet (266 nm) pulsed laser for ionization, two compounds, 4-vinylphenol and indole, which are considered to be important for the characteristic flavor of cooked rice, could be detected from all types of cultivars measured in the present study-nonglutinous rice, glutinous rice, and aromatic rice. In the case of fresh nonglutinous rice, the amounts of introduction for 4-vinylphenol and indole to GC were ca. 70 and 20 pg, respectively. While both peak areas decreased with increases in the time needed to maintain warmth, the decreasing behaviors differed slightly with a noteworthy rapid decrease for indole. For nonglutinous rice, the peak areas for 4-vinylphenol were almost the same, whether it was fresh (measured within 1 month from harvest) or aged (measured 6-12 months after harvest), but those of indole significantly decreased following storage. We also found differences among cultivars: the peak area for 4-vinylphenol in nonglutinous rice was somewhat strong; the peak area for indole was intensely strong in glutinous rice; however, the peak areas for both 4-vinylphenol and indole were weak in aromatic rice. Volatile odor-active compounds were detected in a sensitive and time-resolved manner; therefore, the proposed method could be useful for differentiating varieties of cooked rice from the viewpoints of cooking conditions, freshness, and cultivar types.
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Affiliation(s)
- Ryo Shinoda
- Department
of Materials Science and Engineering, Graduate School of Engineering, University
of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
| | - Keita Takahashi
- Department
of Materials Science and Engineering, Graduate School of Engineering, University
of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
| | - Shunsuke Ichikawa
- Department
of Materials Science and Engineering, Graduate School of Engineering, University
of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
| | - Misato Wakayama
- Department
of Materials Science and Engineering, Graduate School of Engineering, University
of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
| | - Asako Kobayashi
- Fukui
Agricultural Experiment Station, 52-21, Ryo-machi, Fukui 918-8215, Japan
| | - Shinobu Miyagawa
- Department
of Materials Science and Engineering, Graduate School of Engineering, University
of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
| | - Tomohiro Uchimura
- Department
of Materials Science and Engineering, Graduate School of Engineering, University
of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
- . Phone/Fax: +81-776-27-8610
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10
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Affiliation(s)
- Tomohiro Uchimura
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui, 910-8507, Japan
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11
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Takezawa H, Iwata M, Ueyama T, Uchimura T. Using Resonance-Enhanced Multiphoton Ionization Time-of-Flight Mass Spectrometry to Quantitatively Analyze the Creaming of an Emulsion. ACS Omega 2019; 4:20362-20366. [PMID: 31815240 PMCID: PMC6894152 DOI: 10.1021/acsomega.9b02930] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 11/04/2019] [Indexed: 06/10/2023]
Abstract
In this study, we used a quantitative analytical method to indicate creaming behavior in an emulsion. An oil-in-water emulsion was directly measured by resonance-enhanced multiphoton ionization time-of-flight mass spectrometry, and the time profiles of the peak areas of an oil component, styrene, were obtained at heights of 1, 2, and 3 cm from the bottom of a sample that had a height of 4 cm. All time profiles roughly indicated that the signal intensity increased once, then decreased, and finally settled. Moreover, we proposed a fitting equation for the time profiles by subtracting two sigmoid functions, whereby the degree of the signal increases at the initial stage, the degree of the signal decreases after the increase, and the times for continuing the higher signal intensities were all longer as the monitoring positions were raised. This method would surely provide useful information about emulsions that undergo creaming behavior.
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12
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Uchimura T, Kuramitz H, Tomiyasu T. "Analytical Chemistry for Environmental Sciences". ANAL SCI 2019; 35:715. [PMID: 31292351 DOI: 10.2116/analsci.call1907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
| | - Hideki Kuramitz
- Graduate School of Science and Engineering for Research, University of Toyama
| | - Takashi Tomiyasu
- Graduate School of Science and Engineering, Kagoshima University
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13
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Shinoda R, Uchimura T. Evaluating the Creaming of an Emulsion via Mass Spectrometry and UV-Vis Spectrophotometry. ACS Omega 2018; 3:13752-13756. [PMID: 31458075 PMCID: PMC6644440 DOI: 10.1021/acsomega.8b02283] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 10/11/2018] [Indexed: 06/10/2023]
Abstract
The creaming behavior of a turbid oil-in-water emulsion was observed via the processes of multiphoton ionization time-of-flight mass spectrometry (MPI-TOFMS) and ultraviolet-visible spectrophotometry (UV-vis), and the results were compared. The transmittance measurement by UV-vis showed that the turbidity of the toluene emulsion was decreased with time. However, non-negligible errors are common in the measurement of a sample with high turbidity. The online measurement by MPI-TOFMS detected many spikes in the time profile, which revealed the existence of toluene droplets in the emulsion. A smooth time profile suggested that the signal intensity had initially increased, and then decreased with time; the initial concentration of toluene was 3 g/L, which had decreased by half after 60 min. The signal behavior obtained using MPI-TOFMS differed only slightly from that obtained using UV-vis. Since a change in turbidity is not the same as a change in the local concentration of an oil component, MPI-TOFMS is useful for the analysis of a turbid emulsion and offers additional information concerning the creaming phenomenon of an emulsion.
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Abstract
The first quantitative analysis of an oil component in an emulsion was achieved by multiphoton ionization time-of-flight mass spectrometry (MPI-TOFMS). An oil-in-water (O/W) emulsion was prepared. Styrene (0 - 5000 ng μL-1) and Triton X-100 were used as the oil phase and the disperser, respectively. Toluene was employed as an internal standard. We obtained a series of mass spectra, and then constructed the time profiles for styrene and toluene. As a result, we found several spikes from both time profiles when measuring emulsions with higher concentrations of styrene. Moreover, the timing of spikes for toluene coincided with that of styrene. These results suggested the movement of toluene into styrene droplets in the prepared emulsion. Furthermore, we constructed calibration curves of styrene using both the absolute calibration curve method and an internal standard method. Linear calibration curves were obtained in the concentration range investigated in the present study; the coefficients of determination obtained by both methods were 0.9956 and 0.9986, respectively.
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Affiliation(s)
- Hirofumi Fukaya
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui
| | - Tomohiro Uchimura
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui
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15
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Yamamoto H, Ishigami H, Uchimura T. Online Monitoring of a Styrene Monomer and a Dimer in an Emulsion via Laser Ionization Time-of-Flight Mass Spectrometry. ANAL SCI 2018; 33:731-733. [PMID: 28603195 DOI: 10.2116/analsci.33.731] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Laser ionization time-of-flight mass spectrometry was applied to the online monitoring of a styrene monomer and dimer in an emulsion. During the measurement of a styrene monomer oil-in-water emulsion for this study, a styrene dimer, 1,3-diphenylpropane, was dropped into the emulsion. As a result, signal spikes from both analytes occurred simultaneously, which suggested that either the dimer had moved to the monomer droplets or that the monomer and dimer droplets had aggregated. We concluded that this method could be useful for the direct monitoring of monomers and oligomers in the early stages of emulsion polymerization.
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Affiliation(s)
- Hikaru Yamamoto
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui
| | - Hidaka Ishigami
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui
| | - Tomohiro Uchimura
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui
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16
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Tsuda Y, Uchimura T. Evaluating the Aging of Multiple Emulsions Using Resonance-Enhanced Multiphoton Ionization Time-of-Flight Mass Spectrometry. ANAL SCI 2018; 32:789-95. [PMID: 27396662 DOI: 10.2116/analsci.32.789] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Resonance-enhanced multiphoton ionization time-of-flight mass spectrometry was applied to measurements of multiple emulsions with no pretreatment; a method for the quantitative evaluation of aging was proposed. We prepared water-in-oil-in-water (W/O/W) multiple emulsions containing toluene and m-phenylenediamine. The samples were measured immediately following both preparation and after having been stirred for 24 h. Time profiles of the peak areas for each analyte species were obtained, and several intense spikes for toluene could be detected from each sample after stirring, which suggests that the concentration of toluene in the middle phase had increased during stirring. On the other hand, in the case of a W/O/W multiple emulsion containing phenol and m-phenylenediamine, spikes for m-phenylenediamine, rather than phenol, were detected after stirring. In the present study, the time-profile data were converted into a scatter plot in order to quantitatively evaluate the aging. As a result, the ratio of the plots where strong signal intensities of toluene were detected increased from 8.4% before stirring to 33.2% after stirring for 24 h. The present method could be a powerful tool for evaluating multiple emulsions, such as studies on the kinetics of the encapsulation and release of active ingredients.
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Affiliation(s)
- Yukihiro Tsuda
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui
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17
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Shimo Y, Uchimura T. Time-Profile Measurement of an Emulsion Using Multiphoton Ionization Time-of-Flight Mass Spectrometry in Combination with a Microscope. ANAL SCI 2018; 32:1059-1063. [PMID: 27725604 DOI: 10.2116/analsci.32.1059] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Multiphoton ionization time-of-flight mass spectrometry was applied to the measurement of an oil-in-water emulsion that contained toluene as a dispersed phase. Before the measurement, the sample was sufficiently creamed, and then stirred for a short period of time for dispersion. As a result, several intense spikes appeared on the time profile constructed from the peak area for toluene. In the present study, an optical microscope was used to observe the capillary column for sample introduction, and small toluene droplets along with their aggregates were found in the images of the emulsion flowing through the capillary. The aggregates produced intense spikes comprised of multiple plots, which could be easily marked by applying a moving median filter. In the present study, droplets with minimum diameters as small as 2.9 μm, which corresponds to 13 fL, could be calculated as detectable spikes.
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Affiliation(s)
- Yosuke Shimo
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui
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Miyagawa T, Shimizu S, Miura A, Fukuyama A, Uchimura T. Rapid Evaluation of the Bioremediation of Fuel Oil in Soil by Gas Chromatography–Laser Ionization Time-of-Flight Mass Spectrometry. ANAL LETT 2017. [DOI: 10.1080/00032719.2017.1319378] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Tomomi Miyagawa
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui, Fukui, Japan
| | - Shiho Shimizu
- Department of Science and Mathematics Education, Faculty of Education, University of Fukui, Fukui, Japan
| | - Asa Miura
- Department of Science and Mathematics Education, Faculty of Education, University of Fukui, Fukui, Japan
| | - Atsuko Fukuyama
- Headquarters for Innovative Society-Academia Cooperation, University of Fukui, Fukui, Japan
| | - Tomohiro Uchimura
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui, Fukui, Japan
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Uchimura T, Tokumoto G, Batnyam O, Chou CW, Fujita S. Multiphoton Ionization Time-of-Flight Mass Spectrometry for the Detection of Bioactive Lignan. ANAL SCI 2016; 32:255-7. [PMID: 26860576 DOI: 10.2116/analsci.32.255] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Multiphoton ionization time-of-flight mass spectrometry (MPI-TOFMS) combined with a pulsed laser for sample vaporization was developed for the detection of a low-volatile compound in a solution. A solution containing Taiwanin A ((3E,4E)-3,4-bis(1,3-benzodioxol-5-ylmethylene)dihydro-2(3H)-furanone), which is a lignan that has an anticancer effect, was employed in the present study. Consequently, Taiwanin A could be detected by irradiating a laser pulse for vaporization to an inlet nozzle, rather than by heating. Therefore, the present method could be effective for detecting compounds with lower volatilities in a liquid sample.
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Affiliation(s)
- Tomohiro Uchimura
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui
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20
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Kawanabe S, Araki Y, Uchimura T, Imasaka T. Applying fluorescence lifetime imaging microscopy to evaluate the efficacy of anticancer drugs. Methods Appl Fluoresc 2015; 3:025006. [PMID: 29148485 DOI: 10.1088/2050-6120/3/2/025006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Fluorescence lifetime imaging microscopy was applied to evaluate the efficacy of anticancer drugs. A decrease in the fluorescence lifetime of the nucleus in apoptotic cancer cells stained by SYTO 13 dye was detected after treatment with antitumor antibiotics such as doxorubicin or epirubicin. It was confirmed that the change in fluorescence lifetime occurred earlier than morphological changes in the cells. We found that the fluorescence lifetime of the nucleus in the cells treated with epirubicin decreased more rapidly than that of the cells treated with doxorubicin. This implies that epirubicin was more efficacious than doxorubicin in the treatment of cancer cells. The change in fluorescence lifetime was, however, not indicated when the cells were treated with cyclophosphamide. The decrease in fluorescence lifetime was associated with the processes involving caspase activation and chromatin condensation. Therefore, this technique would provide useful information about apoptotic cells, particularly in the early stages.
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Affiliation(s)
- Satoshi Kawanabe
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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21
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Kuraishi T, Uchimura T. Resonance-Enhanced Multiphoton Ionization/Time-of-Flight Mass Spectrometry for Sensitive Analysis of Product Ions Formed by Online Concentration from Analyte Adsorption/Laser Desorption. Anal Chem 2013; 85:3493-6. [DOI: 10.1021/ac303702d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tetsuya Kuraishi
- Department of Materials
Science and Engineering, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507,
Japan
| | - Tomohiro Uchimura
- Department of Materials
Science and Engineering, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507,
Japan
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Abstract
Multiphoton ionization/time-of-flight mass spectrometry (MPI/TOFMS) was modified for the rapid analysis of gasoline-contaminated soil. This technique uses a nanosecond laser emitting at 266 nm, and has the potential to produce the mass spectrum for gasoline 30 min after sampling. The rapidity and robustness of the method can be applied to the screening of gasoline-contaminated soils while minimizing the risk of contamination when gas chromatograph (GC) is used. GC/MPI/TOFMS was used for a simultaneous determination of aromatic compounds of gasoline in a soil sample, and this was achieved without interference. A peak for toluene can be observed from 0.02 ng of gasoline, and ten peaks of aromatic hydrocarbons, which are sensitive to measurement by a laser, can be observed from 0.65 ng of gasoline. The MPI/TOFMS had good sensitivity and selectivity, and was therefore useful for the rapid analysis of gasoline-contaminated soils.
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Affiliation(s)
- Tomohiro Uchimura
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui, Fukui, Japan.
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Miyake R, Uchimura T, Li X, Imasaka T. Fluorescence Lifetime Imaging Microscopy for the Monitoring of Green Fluorescent Protein-Tagged Androgen Receptors in Living Cells. Chem Pharm Bull (Tokyo) 2013; 61:82-4. [DOI: 10.1248/cpb.c12-00428] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Rina Miyake
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University
| | - Tomohiro Uchimura
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University
- Department of Translational Research Center, Center for Future Chemistry, Kyusyu University
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui
| | - Xu Li
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University
- Department of Orthopedic Surgery, First Affiliated Hospital, China Medical University
| | - Totaro Imasaka
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University
- Department of Translational Research Center, Center for Future Chemistry, Kyusyu University
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Uchimura T, Nakamura N, Imasaka T. An ultrashort-duration, high-repetition-rate pulse source for laser ionization/mass spectrometry. Rev Sci Instrum 2012; 83:014101. [PMID: 22299968 DOI: 10.1063/1.3675890] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
This paper describes a sample inlet system with several advantages over other pulsed valves, as applied to resonance-enhanced multiphoton ionization/time-of-flight mass spectrometry. The nozzle is based on online concentration by analyte adsorption/laser desorption (online COLD), where a capillary column with a narrowly synthesized tip is employed for sample introduction. The analyte molecules adsorbed at the tip are desorbed by a pulsed laser and are injected into a mass spectrometer as a packet. The online COLD nozzle can produce very short gas pulses on the order of 1 μs. Moreover, this nozzle is capable of operating over a wide range of repetition rates from 1 Hz to 1 kHz. In addition, this nozzle intrinsically possesses several unique characteristics; for instance, it can be heated to very high temperatures and has nearly zero dead volume. Therefore, the present sample introduction technique offers an ideal and versatile nozzle for laser ionization/mass spectrometry.
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Affiliation(s)
- T Uchimura
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui, Bunkyo, Fukui, Japan.
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Knebel W, Rao N, Uchimura T, Mori A, Fisher J, Gastonguay MR, Chaikin P. Population pharmacokinetic-pharmacodynamic analysis of istradefylline in patients with Parkinson disease. J Clin Pharmacol 2011; 52:1468-81. [PMID: 22162533 DOI: 10.1177/0091270011420566] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This model-based analysis quantifies the population pharmacokinetic-pharmacodynamic efficacy and safety/tolerability relationships of orally administered istradefylline, a selective adenosine A(2A) receptor antagonist, in healthy participants and patients with Parkinson disease. Data from 6 phase 2/3 clinical trials comprised the population database, with 1760 and 1798 patients contributing to the efficacy and safety/tolerability analyses, respectively. The relationship between istradefylline area under the curve at steady state and percentage OFF time was described by a nonlinear model (Emax) based on time for the disease progression/placebo response component and an Emax model for the effect of istradefylline. The typical maximum decrease in percentage OFF time due to istradefylline exposure would be 5.79% (95% confidence interval = 4.09%-7.49%) with one-half of the maximum effect reached at an exposure of 1690 ng × hr/mL (95% confidence interval = 199-3180 ng × hr/mL). The pharmacokinetic-pharmacodynamic relationships for dyskinesia and dizziness were described by an Emax model, and for nausea, a power model was used. The probabilities of dyskinesia and dizziness are expected to plateau at a dose of 40 mg/d, and the probability of nausea is expected to continually rise as the dose is increased. Collectively, these results support a starting istradefylline dose of 20 to 40 mg/d.
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26
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Li A, Uchimura T, Watanabe-Ezoe Y, Imasaka T. Analysis of Dioxins by Gas Chromatography/Resonance-Enhanced Multiphoton Ionization/Mass Spectrometry Using Nanosecond and Picosecond Lasers. Anal Chem 2010; 83:60-6. [DOI: 10.1021/ac101849w] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Adan Li
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744 Motooka, Nishiku, Fukuoka 819-0395, Japan, and College of Chemistry and Environmental Engineering, Yanshan University, Qinhuangdao 066004, China
| | - Tomohiro Uchimura
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744 Motooka, Nishiku, Fukuoka 819-0395, Japan, and College of Chemistry and Environmental Engineering, Yanshan University, Qinhuangdao 066004, China
| | - Yuka Watanabe-Ezoe
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744 Motooka, Nishiku, Fukuoka 819-0395, Japan, and College of Chemistry and Environmental Engineering, Yanshan University, Qinhuangdao 066004, China
| | - Totaro Imasaka
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744 Motooka, Nishiku, Fukuoka 819-0395, Japan, and College of Chemistry and Environmental Engineering, Yanshan University, Qinhuangdao 066004, China
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27
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Tsukatani H, Okudaira H, Shitamichi O, Uchimura T, Imasaka T. Selective determination of 2,4-xylenol by gas chromatography/supersonic jet/resonance-enhanced multiphoton ionization/time-of-flight mass spectrometry. Anal Chim Acta 2010; 682:72-6. [DOI: 10.1016/j.aca.2010.09.043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 09/24/2010] [Accepted: 09/26/2010] [Indexed: 11/29/2022]
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Okudaira H, Uchimura T, Imasaka T. A pair of concentric capillaries as an interface for gas chromatography and supersonic jet/multiphoton ionization/mass spectrometry. Rev Sci Instrum 2010; 81:084102. [PMID: 20815616 DOI: 10.1063/1.3462982] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A pair of concentric capillaries was developed to mix helium, which was used as the carrier gas for gas chromatography, with argon for efficient molecular cooling by supersonic jet expansion. A simple instrument was constructed for the evaluation of nozzle diameter using the Hagen-Poiseuille equation. The effects of nozzle diameter, type of expansion gas, flow rate, and the distance from the nozzle to the observation region were investigated. Mixing argon gas with the carrier gas helium resulted in efficient molecular cooling from 30 to 10 K and the complete disappearance of the background signal from the multiphoton ionization spectrum. Consequently, the spectral selectivity was significantly improved and the nozzle was successfully applied to isomer-selective analysis of dichlorotoluenes. Since the dead volume in the nozzle was negligible, it was suitable as an interface for gas chromatography and supersonic jet/multiphoton ionization/mass spectrometry.
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Affiliation(s)
- H Okudaira
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
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29
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Watanabe-Ezoe Y, Li X, Imasaka T, Uchimura T, Imasaka T. Gas Chromatography/Femtosecond Multiphoton Ionization/Time-of-Flight Mass Spectrometry of Dioxins. Anal Chem 2010; 82:6519-25. [DOI: 10.1021/ac1009063] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yuka Watanabe-Ezoe
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan, Laboratory of Chemistry, Graduate School of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka 815-8540, Japan, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Xing Li
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan, Laboratory of Chemistry, Graduate School of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka 815-8540, Japan, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Tomoko Imasaka
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan, Laboratory of Chemistry, Graduate School of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka 815-8540, Japan, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Tomohiro Uchimura
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan, Laboratory of Chemistry, Graduate School of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka 815-8540, Japan, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Totaro Imasaka
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan, Laboratory of Chemistry, Graduate School of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka 815-8540, Japan, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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Shimizu T, Watanabe-Ezoe Y, Yamaguchi S, Tsukatani H, Imasaka T, Zaitsu SI, Uchimura T, Imasaka T. Enhancement of Molecular Ions in Mass Spectrometry Using an Ultrashort Optical Pulse in Multiphoton Ionization. Anal Chem 2010; 82:3441-4. [DOI: 10.1021/ac1003773] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Takashi Shimizu
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan, Laboratory of Chemistry, Graduate School of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka 815-8540, Japan, and Fukuoka Institute of Health and Environmental Sciences, 39 Mukaizano, Dazaifu, Fukuoka 818-0135, Japan
| | - Yuka Watanabe-Ezoe
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan, Laboratory of Chemistry, Graduate School of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka 815-8540, Japan, and Fukuoka Institute of Health and Environmental Sciences, 39 Mukaizano, Dazaifu, Fukuoka 818-0135, Japan
| | - Satoshi Yamaguchi
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan, Laboratory of Chemistry, Graduate School of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka 815-8540, Japan, and Fukuoka Institute of Health and Environmental Sciences, 39 Mukaizano, Dazaifu, Fukuoka 818-0135, Japan
| | - Hiroko Tsukatani
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan, Laboratory of Chemistry, Graduate School of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka 815-8540, Japan, and Fukuoka Institute of Health and Environmental Sciences, 39 Mukaizano, Dazaifu, Fukuoka 818-0135, Japan
| | - Tomoko Imasaka
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan, Laboratory of Chemistry, Graduate School of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka 815-8540, Japan, and Fukuoka Institute of Health and Environmental Sciences, 39 Mukaizano, Dazaifu, Fukuoka 818-0135, Japan
| | - Shin-ichi Zaitsu
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan, Laboratory of Chemistry, Graduate School of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka 815-8540, Japan, and Fukuoka Institute of Health and Environmental Sciences, 39 Mukaizano, Dazaifu, Fukuoka 818-0135, Japan
| | - Tomohiro Uchimura
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan, Laboratory of Chemistry, Graduate School of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka 815-8540, Japan, and Fukuoka Institute of Health and Environmental Sciences, 39 Mukaizano, Dazaifu, Fukuoka 818-0135, Japan
| | - Totaro Imasaka
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan, Laboratory of Chemistry, Graduate School of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka 815-8540, Japan, and Fukuoka Institute of Health and Environmental Sciences, 39 Mukaizano, Dazaifu, Fukuoka 818-0135, Japan
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31
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Cheng CC, Chang HW, Uchimura T, Imasaka T, Kaneta T, Lin CH. Application of Hadamard transform to gas chromatography/nonresonant multiphoton ionization/time-of-flight mass spectrometry. J Sep Sci 2010; 33:626-30. [DOI: 10.1002/jssc.200900662] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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32
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Sakoda Y, Uchimura T, Imasaka T. Online concentration by analyte adsorption/laser desorption for application to gas chromatography/resonance-enhanced multiphoton ionization time-of-flight mass spectrometry. Anal Chem 2010; 82:1283-7. [PMID: 20085300 DOI: 10.1021/ac902273b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A novel sample introduction technique, based on online concentration by analyte adsorption/laser desorption, was applied to resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS). Signal enhancement and optical selectivity, based on supersonic jet spectrometry, were examined by measuring the REMPI spectra. This sample introduction technique was applied at the interface of a gas chromatograph (GC) and a mass spectrometer (MS). The signal intensity was enhanced ca. 80-fold, compared with that of a conventional technique based on continuous sample introduction. The analyte molecule was selectively measured using a tunable laser emitting at a wavelength of the 0-0 transition. With the use of a desorption laser, a linear calibration curve was extended over 4 orders of magnitude. The sensitivity, selectivity, and dynamic range were all superior for this sample introduction system, as were the inherent characteristics, e.g., a near-zero dead volume and thermal durability. This system would provide a useful means for practical trace analysis of aromatic hydrocarbons by GC/REMPI-TOFMS.
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Affiliation(s)
- Yuji Sakoda
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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Yamaguchi S, Uchimura T, Imasaka T, Imasaka T. Gas chromatography/time-of-flight mass spectrometry of triacetone triperoxide based on femtosecond laser ionization. Rapid Commun Mass Spectrom 2009; 23:3101-3106. [PMID: 19705378 DOI: 10.1002/rcm.4225] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Triacetone triperoxide (TATP), which is used as an explosive in acts of terrorism, was measured by means of gas chromatography/multiphoton ionization/time-of-flight mass spectrometry using a deep-ultraviolet (deep-UV) femtosecond laser as an ionization source. The fragmentation process was investigated by changing the intensity of the laser at the center axis of a molecular beam. A molecular ion was observed using a femtosecond laser, and the ratio of the intensities of the molecular and fragment ions decreased as the intensity of the laser increased. These results suggest that TATP can be efficiently ionized using a deep-UV, ultrashort optical pulse. Furthermore, fragmentation was accelerated by excess energy supplied through higher-order multiphoton processes under a strong radiation field. The detection limits obtained using the molecular ion and two dominant fragment ions, C(2)H(3)O(+) and CH(3) (+), were determined to be 670, 83 and 150 pg, respectively.
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Affiliation(s)
- Satoshi Yamaguchi
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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Uchimura T, Yamaguchi S, Imasaka T. Development of an Off-axis Sample Introduction System for Use in Multiphoton Ionization/Time-of-flight Mass Spectrometry. CHEM LETT 2009. [DOI: 10.1246/cl.2009.744] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Takase K, Uchimura T, Yamamoto M, Yamada S. Susceptibility of embryos and chicks, derived from immunized breeding hens, to avian nephritis virus. Avian Pathol 2009; 23:117-25. [PMID: 18671076 DOI: 10.1080/03079459408418979] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
High virus-neutralizing antibodies were induced in specific-pathogen-free breeding hens by administration of live and killed avian nephritis virus (ANV), strain M-8, antigens. Ten-day-old embryos from immune hens survived challenge by ANV which was administered by the yolk sac or allantoic cavity route. When the progeny chicks from immune dams were infected with ANV orally or by contact challenge, the virus replicated in the intestine. However, they were protected against pathological damage and virus replication in the kidney. The chicks without maternal antibodies showed apparent renal lesions and virus replication to high titre in the kidneys.
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Affiliation(s)
- K Takase
- Chemo-Sero-Therapeutic Research Institute, Shimizu-cho, Kumamoto 860, Japan
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Uchimura T, Araki Y, Kawanabe S, Miyake R, Imasaka T. Development of Fluorescence Lifetime Imaging Microscope Using Tunable Picosecond Laser for Application to Living Cells. BUNSEKI KAGAKU 2009. [DOI: 10.2116/bunsekikagaku.58.487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Tomohiro Uchimura
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University
- Division of Translational Research, Center for Future Chemistry, Kyushu University
| | - Yoshie Araki
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University
| | - Satoshi Kawanabe
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University
| | - Rina Miyake
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University
| | - Totaro Imasaka
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University
- Division of Translational Research, Center for Future Chemistry, Kyushu University
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Yamaguchi S, Kira F, Miyoshi Y, Uchimura T, Watanabe-Ezoe Y, Zaitsu SI, Imasaka T, Imasaka T. Near-ultraviolet femtosecond laser ionization of dioxins in gas chromatography/time-of-flight mass spectrometry. Anal Chim Acta 2009; 632:229-33. [DOI: 10.1016/j.aca.2008.11.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Revised: 10/25/2008] [Accepted: 11/02/2008] [Indexed: 11/16/2022]
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Imasaka T, Nakamura N, Sakoda Y, Yamaguchi S, Watanabe-Ezoe Y, Uchimura T, Imasaka T. Data processing technique in gas chromatography/time-of-flight mass spectrometry. Analyst 2009; 134:712-8. [DOI: 10.1039/b815630a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Affiliation(s)
- Tomohiro Uchimura
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University
- Division of Translational Research, Center for Future Chemistry, Kyushu University
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Rao N, Dvorchik B, Sussman N, Wang H, Yamamoto K, Mori A, Uchimura T, Chaikin P. A study of the pharmacokinetic interaction of istradefylline, a novel therapeutic for Parkinson's disease, and atorvastatin. J Clin Pharmacol 2008; 48:1092-8. [PMID: 18552277 DOI: 10.1177/0091270008320924] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The effect of steady-state istradefylline, an agent for Parkinson's disease with P-glycoprotein and CYP3A inhibitory activity, on the pharmacokinetics of atorvastatin and its metabolites was evaluated in healthy volunteers. A single 40-mg dose of atorvastatin was administered to 20 subjects. After a 4-day washout, subjects received a single 40-mg atorvastatin dose following 40 mg istradefylline (n=16) or placebo (n=4) daily for 14 days. Plasma samples collected for 96 hours after atorvastatin administration, alone and in combination, were analyzed for atorvastatin, orthohydroxy atorvastatin, and parahydroxy atorvastatin. Istradefylline increased atorvastatin C(max) (53%), AUC(0-infinity) (54%), and t((1/2)) (27%); and increased AUC(0-infinity) for orthohydroxy atorvastatin (18%), but had no significant effect on its C(max) or t((1/2)); and had minimal effect on parahydroxy atorvastatin AUC(0-infinity). The lack of inhibition by istradefylline on metabolite systemic exposure, combined with increased atorvastatin systemic exposure, suggests a predominant P-glycoprotein inhibitory effect of istradefylline.
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Affiliation(s)
- N Rao
- Kyowa Pharmaceutical Inc, 212 Carnegie Center, Suite 101, Princeton, NJ 08540, USA.
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Itoh T, Uchimura T, Uchida T, Kawano M, Imasaka T. GC–MPI–MS of Pentachlorodibenzofurans in Flue Gas Using a UV Picosecond Laser. Chromatographia 2008. [DOI: 10.1365/s10337-008-0648-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Uchimura T, Sakoda Y, Imasaka T. On-Line Concentration by Analyte Adsorption and Subsequent Laser Desorption in Supersonic Jet Spectrometry. Anal Chem 2008; 80:3798-802. [DOI: 10.1021/ac8000176] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tomohiro Uchimura
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Yuji Sakoda
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Totaro Imasaka
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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Li X, Uchimura T, Kawanabe S, Imasaka T. Use of a fluorescence lifetime imaging microscope in an apoptosis assay of Ewing’s sarcoma cells with a vital fluorescent probe. Anal Biochem 2007; 367:219-24. [PMID: 17543878 DOI: 10.1016/j.ab.2007.04.032] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Revised: 04/06/2007] [Accepted: 04/23/2007] [Indexed: 11/18/2022]
Abstract
A fluorescence lifetime imaging microscope (FLIM) was applied to study early-stage apoptotic cells stained with a SYTO13 dye. The fluorescence lifetime of SYTO13 in healthy cells was 3.8+/-0.3ns but was reduced to 2.4+/-0.4 and 1.9+/-0.2ns after a 3-h period of incubation with SYTO13 when doxorubicin, a known inducer of apoptosis, was added to human Ewing's family tumor cells at final concentrations of 250 and 500nM, respectively, in a dose-dependent experiment. On the other hand, in a time-dependent experiment, the fluorescence lifetime decreased to 2.5+/-0.5 and 1.7+/-0.4ns at a doxorubicin concentration of 750nM after 2 and 4h, respectively. A possible explanation for these results is self-quenching induced by a change in interprobe distance that arises from the condensation of DNA during apoptosis. In this study, the FLIM system was employed to investigate early-stage apoptosis that involves only small morphological changes, suggesting the potential advantage of this method for evaluating small biological effects in living cells.
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Affiliation(s)
- Xu Li
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan
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Zaitsu SI, Miyoshi Y, Kira F, Yamaguchi S, Uchimura T, Imasaka T. Interferometric characterization of ultrashort deep ultraviolet pulses using a multiphoton ionization mass spectrometer. Opt Lett 2007; 32:1716-8. [PMID: 17572757 DOI: 10.1364/ol.32.001716] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The temporal characterization of a femtosecond laser pulse in the deep ultraviolet region using an interferometric autocorrelation scheme is demonstrated. Two-photon ionization of a molecule in a time-of-flight mass spectrometer was used as a nonlinear detector to obtain an autocorrelation trace. This setup proved useful in not only providing a temporal characterization of a pulse but also investigating the ultrafast dynamics of photochemical processes.
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Affiliation(s)
- Shin-ichi Zaitsu
- Graduate School of Engineering, Kyushu University, Fukuoka, Japan
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Uchimura T, Kawanabe S, Maeda Y, Imasaka T. Fluorescence lifetime imaging microscope consisting of a compact picosecond dye laser and a gated charge-coupled device camera for applications to living cells. ANAL SCI 2007; 22:1291-5. [PMID: 17038764 DOI: 10.2116/analsci.22.1291] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
An inverted microscope was combined with a compact dye laser with a pulse width of <190 ps and an intensified charge-coupled device (ICCD) camera with a minimum gate width of 200 ps. The resulting fluorescence lifetime imaging microscope, which has a temporal resolution of 340 ps, was used to measure the fluorescence lifetime of polymer microspherers. The results indicated a fluorescence lifetime of 0.9 ns. The present analytical instrument was also employed in an evaluation of biological cells after labeling them with SYTO 13, a fluorescent dye.
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Affiliation(s)
- Tomohiro Uchimura
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, Fukuoka, Japan
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Rao N, Chaikin P, Allenby K, Dvorchik B, Mori A, Uchimura T. 2.226 Electrocardiogram effects of istradefylline: A thorough QTc study in healthy men and women. Parkinsonism Relat Disord 2007. [DOI: 10.1016/s1353-8020(08)70637-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Yamaguchi S, Uchimura T, Imasaka T. Gas Chromatography/Multiphoton Ionization/Mass Spectrometry of Polychlorinated Dibenzofurans Using Nanosecond and Femtosecond Lasers. ANAL SCI 2006; 22:1483-7. [PMID: 17159303 DOI: 10.2116/analsci.22.1483] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Gas chromatography/multiphoton ionization/time-of-flight mass spectrometry (GC/MPI/TOF-MS) using a femtosecond laser source has been developed and applied to analysis of an authentic sample containing five polychlorinated dibenzofurans (PCDFs). The ionization efficiency was substantially improved for compounds such as tetrachlorinated dibenzofuran (tetraCDF) and pentachlorinated dibenzofuran (pentaCDF) using a femtosecond laser, instead of a nanosecond laser currently used for this purpose. The relatively poor efficiencies in nanosecond ionization can be attributed to the short lifetimes of the singlet excited states that are efficiently relaxed to triplet levels by intersystem crossing. The detection limits for pentaCDF isomers, i.e., 1,2,3,8,9-pentaCDF (non-toxic) and 1,2,3,7,8-pentaCDF (toxic), were determined to be ca. 100 pg, when the femtosecond laser was employed. The present method has the potential for use in the detection and determination of toxic PCDD/Fs in exhaust gas from an incinerator, because of the high inherent selectivity of GC and the high sensitivity of MPI/TOF-MS.
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Affiliation(s)
- Satoshi Yamaguchi
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, Fukuoka, Japan
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Uchimura T, Deguchi T, Imasaka T. Development of a Narrow-Band Tunable Picosecond Dye Laser and Its Application to Excited-State Lifetime Measurement of a Chlorinated Aromatic Hydrocarbon. ANAL SCI 2005; 21:693-5. [PMID: 15984208 DOI: 10.2116/analsci.21.693] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The development of a distributed-feedback dye laser, with a pulse width and a line width of 25 ps and 8.78 pm, respectively, is described. Using this nearly Fourier-transform-limited pulse, we measured the first singlet-excited-state lifetime of 1,2,4-trichlorobenzene. The tunable picosecond dye laser developed herein has a potential for the lifetime measurement and the efficient multiphoton ionization of aromatic hydrocarbons with a larger number of chlorine atoms and shorter excited-state lifetimes.
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Affiliation(s)
- Tomohiro Uchimura
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
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Uchimura T. Sensitive and Selective Analysis of Polychlorinated Dibenzo-p-dioxins/Dibenzofurans and Their Precursors by Supersonic Jet/Resonance-Enhanced Multiphoton Ionization/Time-of-Flight Mass Spectrometry. ANAL SCI 2005; 21:1395-400. [PMID: 16379376 DOI: 10.2116/analsci.21.1395] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), some of which are extremely toxic, are present at low concentrations in incinerator flue gases. The on-line real-time measurement of these compounds is necessary, since these concentrations fluctuate drastically with the process conditions used. Supersonic jet/resonance-enhanced multiphoton ionization/time-of-flight mass spectrometry (SSJ/REMPI/TOF-MS), which provides both high selectivity and sensitivity, appears suitable for application to the on-line real-time monitoring of PCDD/Fs. In this review, the resonant ionization wavelengths of PCDD/Fs and their precursors are given. Moreover, improvements in SSJ/REMPI/TOF-MS that lead to enhanced sensitivity and selectivity are presented. That is, novel ionization sources and advanced ionization schemes are reported for the sensitive measurement of PCDD/Fs and their precursors. Those techniques are advantageous for the trace analysis of these compounds.
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Affiliation(s)
- Tomohiro Uchimura
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, Department of Translational Research, Center of Future Chemistry, Kyushu University, Fukuoka, Japan.
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Uchimura T, Sakai K, Imasaka T. Selective Multiphoton Ionization of Coplanar Polychlorobiphenyls Using 266-nm Laser Emission by Gas Chromatography/Mass Spectrometry. Anal Chem 2004; 76:5534-8. [PMID: 15362917 DOI: 10.1021/ac049496j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Polychlorinated biphenyls (PCBs), used as a heat exchange oil (Kanechlor, KC-300), can be measured by gas chromatography combined with multiphoton ionization mass spectrometry (GC/MPI-MS). Several compounds, e.g., 4,4'-dichlorobiphenyl and 3,4,4'-trichlorobiphenyl, have nearly the same retention time but can be selectively determined by MPI-MS. Coplanar PCBs are more efficiently ionized using the fourth harmonic emission of a Nd:YAG laser (266 nm), compared to noncoplanar PCBs. Thus, the approach reported herein may be useful in the selective as well as the sensitive analysis of toxic PCBs, contained in old transformers and capacitors that have been mandated by the government to be properly disposed of within 10 years in Japan.
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Affiliation(s)
- Tomohiro Uchimura
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, Hakozaki, Fukuoka, 812-8581, Japan
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