Mechanistic Borderline of One-Step Hydrogen Atom Transfer versus Stepwise Sc³⁺-Coupled Electron Transfer from Benzyl Alcohol Derivatives to a Non-Heme Iron(IV)-Oxo Complex

Morimoto, Yuma,Park, Jiyun,Suenobu, Tomoyoshi,Lee, Yong-Min,Nam, Wonwoo,Fukuzumi, Shunichi American Chemical Society 2012 Inorganic Chemistry Vol.51 No.18

<P>The rate of oxidation of 2,5-dimethoxybenzyl alcohol (2,5-(MeO)<SUB>2</SUB>C<SUB>6</SUB>H<SUB>3</SUB>CH<SUB>2</SUB>OH) by [Fe<SUP>IV</SUP>(O)(N4Py)]<SUP>2+</SUP> (N4Py = <I>N</I>,<I>N</I>-bis(2-pyridylmethyl)-<I>N</I>-bis(2-pyridyl)methylamine) was enhanced significantly in the presence of Sc(OTf)<SUB>3</SUB> (OTf<SUP>–</SUP> = trifluoromethanesulfonate) in acetonitrile (e.g., 120-fold acceleration in the presence of Sc<SUP>3+</SUP>). Such a remarkable enhancement of the reactivity of [Fe<SUP>IV</SUP>(O)(N4Py)]<SUP>2+</SUP> in the presence of Sc<SUP>3+</SUP> was accompanied by the disappearance of a kinetic deuterium isotope effect. The radical cation of 2,5-(MeO)<SUB>2</SUB>C<SUB>6</SUB>H<SUB>3</SUB>CH<SUB>2</SUB>OH was detected in the course of the reaction in the presence of Sc<SUP>3+</SUP>. The dimerized alcohol and aldehyde were also produced in addition to the monomer aldehyde in the presence of Sc<SUP>3+</SUP>. These results indicate that the reaction mechanism is changed from one-step hydrogen atom transfer (HAT) from 2,5-(MeO)<SUB>2</SUB>C<SUB>6</SUB>H<SUB>3</SUB>CH<SUB>2</SUB>OH to [Fe<SUP>IV</SUP>(O)(N4Py)]<SUP>2+</SUP> in the absence of Sc<SUP>3+</SUP> to stepwise Sc<SUP>3+</SUP>-coupled electron transfer, followed by proton transfer in the presence of Sc<SUP>3+</SUP>. In contrast, neither acceleration of the rate nor the disappearance of the kinetic deuterium isotope effect was observed in the oxidation of benzyl alcohol (C<SUB>6</SUB>H<SUB>5</SUB>CH<SUB>2</SUB>OH) by [Fe<SUP>IV</SUP>(O)(N4Py)]<SUP>2+</SUP> in the presence of Sc(OTf)<SUB>3</SUB>. Moreover, the rate constants determined in the oxidation of various benzyl alcohol derivatives by [Fe<SUP>IV</SUP>(O)(N4Py)]<SUP>2+</SUP> in the presence of Sc(OTf)<SUB>3</SUB> (10 mM) were compared with those of Sc<SUP>3+</SUP>-coupled electron transfer from one-electron reductants to [Fe<SUP>IV</SUP>(O)(N4Py)]<SUP>2+</SUP> at the same driving force of electron transfer. This comparison revealed that the borderline of the change in the mechanism from HAT to stepwise Sc<SUP>3+</SUP>-coupled electron transfer and proton transfer is dependent on the one-electron oxidation potential of benzyl alcohol derivatives (ca. 1.7 V vs SCE).</P><P>This Article scrutinizes the borderline of the reaction mechanism between one-step hydrogen atom transfer and electron transfer in the oxidation of benzyl alcohol derivatives by a nonheme iron(IV)-oxo complex in the presence of Sc<SUP>3+</SUP>. The borderline is found by examining the dependence of reaction rate constants on the driving force for electron transfer from substrate to the oxidant.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/inocaj/2012/inocaj.2012.51.issue-18/ic3016723/production/images/medium/ic-2012-016723_0015.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ic3016723'>ACS Electronic Supporting Info</A></P>

DC Rail Side Series Switch and Parallel Capacitor Snubber-Assisted Edge Resonant Soft-Switching PWM DC-DC Converter with High-Frequency Transformer Link

Morimoto, Keiki,Fathy, Khairy,Ogiwara, Hiroyuki,Lee, Hyun-Woo,Nakaoka, Mutsuo The Korean Institute of Power Electronics 2007 JOURNAL OF POWER ELECTRONICS Vol.7 No.3

This paper presents a novel circuit topology of a DC bus line series switch and parallel snubbing capacitor-assisted soft-switching PWM full-bridge inverter type DC-DC power converter with a high frequency planar transformer link, which is newly developed for high performance arc welding machines in industry. The proposed DC-DC power converter circuit is based upon a voltage source-fed H type full-bridge soft-switching PWM inverter with a high frequency transformer. This DC-DC power converter has a single power semiconductor switching device in series with an input DC low side rail and loss less snubbing capacitor in parallel with the inverter bridge legs. All the active power switches in the full-bridge arms and DC bus line can achieve ZCS turn-on and ZVS turn-off transition commutation. Consequently, the total switching power losses occurred at turn-off switching transition of these power semiconductor devices; IGBTs can be reduced even in higher switching frequency bands ranging from 20 kHz to 100 kHz. The switching frequency of this DC-DC power converter using IGBT power modules can be realized at 60 kHz. It is proved experimentally by power loss analysis that the more the switching frequency increases, the more the proposed DC-DC power converter can achieve a higher control response performance and size miniaturization. The practical and inherent effectiveness of the new DC-DC converter topology proposed here is actually confirmed for low voltage and large current DC-DC power supplies (32V, 300A) for TIG arc welding applications in industry.

A terminology for the taxonomy of Weevil larvae : Coleoptera:Curculionoidea

Morimoto,Katsura,Lee,Chang-Young 江原大學校 林科大學 森林科學硏究所 1989 Journal of Forest Science Vol.6 No.-

바구미 上科 甲蟲은 世界的으로 6萬種의 記綠이 있는 動物界 最大의 分類群으로서 특히 바구미科, 소나무좀科는 林木의 穿孔性 害蟲으로서 重要時되고 있다. 이들 幼蟲의 硏究는 系統分類學上 重要할 뿐만 아니라 害蟲을 幼蟲으로서 同定한다는 應用面으로도 林業的인 次元에서 대단히 必要함에 本 論文에서는 바구미上科 幼蟲의 形態를 詳細히 관찰 比較硏究에 Key가 되는 形質에 관하여 調査하였다. 1. 頭部 : 單眼, 觸角, 上唇, 下唇, 頭楯, 大시 小시鬚, 剌毛, 感覺孔, 前頭縫合線, 上咽頭, 上咽頭帶 2. 胸部·腹部 : 前背板, 後背板, 氣門, 上側板, 側板, 肢部, 胸部와 第1腹節의 皺와 筋肉의 關係, 剌毛

Real-Time, in Situ Monitoring of the Oxidation of Graphite: Lessons Learned

Morimoto, Naoki,Suzuki, Hideyuki,Takeuchi, Yasuo,Kawaguchi, Shogo,Kunisu, Masahiro,Bielawski, Christopher W.,Nishina, Yuta American Chemical Society 2017 Chemistry of materials Vol.29 No.5

<P>Graphite oxide (GO) and its constituent layers (i.e., graphene oxide) display a broad range of functional groups and, as such, have attracted significant attention for use in numerous applications. GO is commonly prepared using the 'Hummers method' or a variant thereof in which graphite is treated with KMnO4 and various additives in H2SO4. Despite its omnipresence, the underlying chemistry of such oxidation reactions is not well understood and typically affords results that are irreproducible and, in some cases, unsafe. To overcome these limitations, the oxidation of graphite under Hummers-type conditions was monitored over time using in situ X-ray diffraction and in situ X-ray absorption near edge structure analyses with synchrotron radiation. In conjunction with other atomic absorption spectroscopy, UV vis spectroscopy and elemental analysis measurements, the underlying mechanism of the oxidation reaction was elucidated, and the reaction conditions were optimized. Ultimately, the methodology for reproducibly preparing GO on large scales using only graphite, H2SO4 and KMnO4 was developed and successfully adapted for use in continuous flow systems.</P>

Dependence of Weibull parameters on the diameter and the internal defects of Tyranno ZMI fiber in the strength analysis

Morimoto, Tetsuya,Yamamoto, Koji,Ogihara, Shinji The Korean Society for Composite Materials 2007 Advanced composite materials Vol.16 No.3

The single-modal Weibull model has been assessed on Tyranno ZMI Si-Zr-C-O fiber if a set of shape and scale parameters accurately reproduced the effect of the size of the diameter on strength. The tensile data of a single fiber have been divided into two expedient groups as 'small diameter' group and 'large diameter' group in deriving the parameters, which should be consistent if the Weibull model accurately reproduced the size effect. However, the derived Weibull parameters were inconsistent between the two groups. Thereby the authors have concluded that the parameters of the single-modal Weibull model are dependent on the fiber diameter, so that the model is inadequate to reproduce the strength size effect. On the other hand, Weibull parameters were found consistent between the two groups by excluding the data of 'large mirror zone' sample, which was defined as the sample around 10% mirror zone area of the fracture surface. What is more, the exclusion reduced the strength variance more drastically in the 'large diameter' group than in the 'small diameter' group, even though the 'large mirror zone' samples were found identical in the percentage between the two groups. The authors therefore conclude that diameter limitation to the 'small diameter' group level can lead to drastically less distributed strength values than the estimated strength through the Weibull scaling on the present Tyranno ZMI Si-Zr-C-O fiber.

The Probable Primality of the Numbers (xⁿ-1)/(x-1)

Morimoto, Mitsuo 단국대학교 통계문제연구소 1984 數學 및 統計硏究 Vol.12 No.-

Hybrid Capacitors Using Organic Electrolytes

Morimoto, T.,Che, Y.,Tsushima, M. The Korean Electrochemical Society 2003 한국전기화학회지 Vol.6 No.3

Electric double-layer capacitors based on charge storage at the interface between a high surface area activated carbon electrode and an electrolyte solution are characterized by their long cycle-life and high power density in comparison with batteries. However, energy density of electric double-layer capacitors obtained at present is about 6 Wh/kg at a power density of 500W/kg which is smaller as compared with that of batteries and limits the wide spread use of the capacitors. Therefore, a new capacitor that shows larger energy density than that of electric double-layer capacitors is proposed. The new capacitor is the hybrid capacitor consisting of activated carbon cathode, carbonaceous anode and an organic electrolyte. Maximum voltage applicable to the cell is over 4.2V that is larger than that of the electric double-layer capacitor. As a result, discharged energy density on the basis of stacked volume of electrode, current collector and separator is more than 18Wh/l at a power density of 500W/l.

Dual Utility AC Line Voltage Operated Voltage Source and Soft Switching PWM DC-DC Converter with High Frequency Transformer Link for Arc Welding Equipment

Morimoto Keiki,Ahmed NabilA.,Lee Hyun-Woo,Nakaoka Mutsuo The Korean Institute of Electrical Engineers 2005 KIEE International Transactions on Electrical Mach Vol.b5 No.4

This paper presents two new circuit topologies of the dc busline side active resonant snubber assisted voltage source high frequency link soft switching PWM full-bridge dc-dc power converters acceptable for either utility ac 200V-rms or ac 400V-rms input grid. These high frequency switching dc-dc converters proposed in this paper are composed of a typical voltage source-fed full-bridge PWM inverter, high frequency transformer with center tap, high frequency diode rectifier with inductor input filter and dc busline side series switches with the aid of a dc busline parallel capacitive lossless snubber. All the active switches in the full-bridge arms as well as dc busline snubber can achieve ZCS turn-on and ZVS turn-off transition commutation with the aid of a transformer leakage inductive component and consequently the total switching power losses can be effectively reduced. So that, a high switching frequency operation of IGBTs in the voltage source full bridge inverter can be actually designed more than about 20 kHz. It is confirmed that the more the switching frequency of full-bridge soft switching inverter increases, the more soft switching PWM dc-dc converter with a high frequency transformer link has remarkable advantages for its power conversion efficiency and power density implementations as compared with the conventional hard switching PWM inverter type dc-dc power converter. The effectiveness of these new dc-dc power converter topologies can be proved to be more suitable for low voltage and large current dc-dc power supply as arc welding equipment from a practical point of view.

Sustainable Industry-Academia-Government Collaborative Education Focusing on Advantages of Industry: Long-term Internship after 5years Practice

Morimoto, Emi,Yamanaka, Hideo Korean Society for Engineering Education 2012 공학교육연구 Vol.15 No.5

Practical problem-solving studies in a company or organization have provided great advantages for our university and students. For example, such studies can lead them to build a stronger relationship with local governments and companies as well as develop their research through collaborative studies. On the other hand, comments from companies or organizations that accepted our students showed that they did not always have advantages. This study seeks ways to establish a sustainable long-term internship program that can offer advantages for companies. Advantages and disadvantages of the internship are written by the company on the evaluated sheet. These feedback comments are analyzed by text-mining approach. It is shown that there are three types of company and organizations depending on their reasons for accepting students. Next, suitable internship programs for each type, including their period and expense distribution are presented.

A Novel type of High-Frequency Transformer Linked Soft-Switching PWM DC-DC Power Converter for Large Current Applications

Morimoto Keiki,Ahmed Nabil A.,Lee Hyun-Woo,Nakaoka Mutsuo The Korean Institute of Electrical Engineers 2006 Journal of Electrical Engineering & Technology Vol.1 No.2

This paper presents a new circuit topology of DC busline switch and snubbing capacitor-assisted full-bridge soft-switching PWM inverter type DC-DC power converter with a high frequency link for low voltage large current applications as DC feeding systems, telecommunication power plants, automotive DC bus converters, plasma generator, electro plating plants, fuel cell interfaced power conditioner and arc welding power supplies. The proposed power converter circuit is based upon a voltage source-fed H type full-bridge high frequency PWM inverter with a high frequency transformer link. The conventional type high frequency inverter circuit is modified by adding a single power semiconductor switching device in series with DC rail and snubbing lossless capacitor in parallel with the inverter bridge legs. All the active power switches in the full-bridge inverter arms and DC busline can achieve ZVS/ZVT turn-off and ZCS turn-on commutation operation. Therefore, the total switching losses at turn-off and turn-on switching transitions of these power semiconductor devices can be reduced even in the high switching frequency bands ranging from 20 kHz to 100 kHz. The switching frequency of this DC-DC power converter using IGBT power modules is selected to be 60 kHz. It is proved experimentally by the power loss analysis that the more the switching frequency increases, the more the proposed DC-DC converter can achieve high performance, lighter in weight, lower power losses and miniaturization in size as compared to the conventional hard switching one. The principle of operation, operation modes, practical and inherent effectiveness of this novel DC-DC power converter topology is proved for a low voltage and large current DC-DC power supplies of arc welder applications in industry.