Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
-carrageenan oligomers as plant growth promoterAbad, L.*; Saiki, Seiichi; Nagasawa, Naotsugu; Kudo, Hisaaki*; Katsumura, Yosuke*; Dela Rosa, A. M.*
Radiation Physics and Chemistry, 80(9), p.977 - 982, 2011/09
Times Cited Count：15 Percentile：73.97(Chemistry, Physical)The optimum molecular weight of irradiated -carrageenan for the plant growth promoting effect is known to be around 10 kDa, which is obtained by irradiation at doses of 100 kGy in solid and of 2 kGy in 1% aqueous solution. In this study, isolated fraction by membrane filter of irradiated -carrageenan was analyzed by NMR. The chemical shifts of 
C and 
H spectra at the range of 3-10 kDa indicated that the basic functional structure of -carrageenan (alternating D-galactose-4-sulfate and 3,6-anhydro-D-galactose dimer) remains intact. No radiolytic product having carbonyl groups was detected at the range of 3-10 kDa, and moved to less than 3 kDa probably. From these results, it is assumed that the plant growth promoting effect of irradiated -carrageenan depends on the molecular weight, its intact structure, and not on the radiolytic products.
Saiki, Seiichi; Nagasawa, Naotsugu; Hiroki, Akihiro; Morishita, Norio; Tamada, Masao; Kudo, Hisaaki*; Katsumura, Yosuke*
Radiation Physics and Chemistry, 80(2), p.149 - 152, 2011/02
Times Cited Count：18 Percentile：77.43(Chemistry, Physical)Carboxymethyl cellulose (CMC), one of polysaccharide derivatives, at highly concentrated aqueous solution undergoes radiation-crosslinking reactions. In this topic, CMC radical, formed by reaction with OH radical attributed to radiation-induced crosslinking reaction, were studied by ESR method to understand the radiation-induced reaction mechanism of CMC aqueous solution. At first, it was succeeded to observe ESR spectra of the CMC radical using photolysis of hydrogen peroxide as the origin of OH radical. Observed ESR spectra were identified as radicals located on the secondary carbon of carboxymethyl groups. Secondly, N
O saturated CMC aqueous solution 6 min after electron beam irradiation was measured by ESR method. The spectra were almost same shape as the case of photolysis of hydrogen peroxide, and were assigned as long-lived radicals located on carboxymethyl groups. Next, in the case of N and O saturation, spectra intensity become half or 0. This means that these long-lived radicals are produced by reaction with OH radical.
Saiki, Seiichi; Nagasawa, Naotsugu; Hiroki, Akihiro; Morishita, Norio; Tamada, Masao; Muroya, Yusa*; Kudo, Hisaaki*; Katsumura, Yosuke*
Radiation Physics and Chemistry, 79(3), p.276 - 278, 2010/03
Times Cited Count：12 Percentile：59.22(Chemistry, Physical)Carboxymethyl chitosan (CMCTS) is one kind of polysaccharide derivatives and has a good water-solubility. At a high concentrated aqueous solution, CMCTS forms gel by ionizing irradiation, though polysaccharide derivatives are generally radiation-degradation type. In general, OH radical, which is one of main water radiolysis products and very oxidative species, is said to induce crosslinking reaction of polymer solution. The purpose of this study is to understand the radiation-crosslinking mechanism of CMCTS at a high concentrated aqueous solution. In this study, identification of CMCTS radical produced by reaction with OH radical was introduced. CMCTS radical in an aqueous solution was observed directly by ESR method using photolysis of hydrogen peroxide. The ESR spectra have a large doublet split and small triplet split like [Triplet 
Doublet]. However, some species seemed to be overlapped on ESR spectra, because right-and-left triplet spectra are not equiform. Compared with some radicals, which have analogical structure to CMCTS, about hyperfine coupling constant, [Triplet Doublet], assigned as radical on carboxymethyl group linked to C6, and [Doublet], assigned as radical on carboxymethyl group linked to C2 or C3, were isolated from ESR spectra of experimental results. In conclusion, these spectra were identified as radicals located on secondary carbon of carboxymethyl groups.
10% enriched uranyl nitrate solution (Contract research)Onodera, Seiji; Sono, Hiroki; Hirose, Hideyuki; Tanino, Shuichi; Nagasawa, Makoto*; Murakami, Kiyonobu; Sakuraba, Koichi; Miyauchi, Masakatsu; Yamane, Yuichi; Ono, Akio
JAERI-Tech 2000-013, p.57 - 0, 2000/03
JAERI-Tech-2000-013.pdf:2.43MB
no abstracts in English
10% enriched uranyl nitrate solution (Contract research)Onodera, Seiji; Sono, Hiroki; Hirose, Hideyuki; Tanino, Shuichi; Nagasawa, Makoto*; Murakami, Kiyonobu; Sakuraba, Koichi; Miyauchi, Masakatsu; Kikuchi, Tsukasa; Ono, Akio
JAERI-Tech 99-084, p.54 - 0, 1999/12
no abstracts in English
; ; Hirose, Hideyuki; *; *; Murakami, Kiyonobu; Takahashi, Tsukasa; Sakuraba, Koichi; Miyauchi, Masakatsu; ; et al.
JAERI-Tech 98-023, 66 Pages, 1998/06
no abstracts in English
Saiki, Seiichi*; Muroya, Yusa*; Kudo, Hisaaki*; Katsumura, Yosuke*; Nagasawa, Naotsugu; Yoshii, Fumio; Tamada, Masao
no journal, ,
Some kinds of polysaccharide derivatives in an aqueous solution, for example carboxymethyl cellulose (CMC) and carboxymethyl chitin/chitosan (CMCT/CMCTS) etc, become crosslinked and form hydrogels in case of concentrated solution. To study the early process of hydrogelation of polysaccharide derivatives by ionizing irradiation, we evaluated the reactivity of OH radical and hydrated electron with polymer chains by pulse radiolysis technique. And measuring absorbance at around 300 nm for about 1 hour, we confirmed the steady absorbance in case of CMCTS solution and the slow decay of absorbance in case of CMC. We assumed that some polymer radicals are produced after irradiation and diminish by some reactions. To study the change of the absorption spectrum, we measured the spectrum of these polymer solution after irradiation by ultraviolet-visible spectroscopy.
Saiki, Seiichi*; Muroya, Yusa*; Kudo, Hisaaki*; Katsumura, Yosuke*; Nagasawa, Naotsugu; Tamada, Masao
no journal, ,
no abstracts in English
Saiki, Seiichi; Muroya, Yusa*; Kudo, Hisaaki*; Katsumura, Yosuke*; Nagasawa, Naotsugu; Tamada, Masao
no journal, ,
Carboxymethyl cellulose (CMC) forms gels at high concentrated solution by irradiation. It seems that polymer radicals produced by reactions between OH of water radiolysis products and polymer chains reacts with each other. To explain the mechanism of the crosslinking reaction, we study the behavior of polymer radicals in irradiated CMC aqueous solution. Measuring the change of the UV absorption spectrum by electron beam pulse radiolysis method, we confirmed the slow decay of absorbance for about 30 minutes at 10 mM CMC concentration, and the decay was slower with increasing CMC concentration. Next, CMC samples, which molecular weight was different and which degree of substitution of carboxymethyl group were almost same, was measured at the same 20 mM concentration. The result showed that the initial absorbance was almost same and that the decay of absorbance was slower with increasing molecular weight. From these results, we assumed that viscous property of CMC aqueous solution have littile influence on the yield but have some on reaction rate.
Saiki, Seiichi; Muroya, Yusa*; Nagasawa, Naotsugu; Tamada, Masao; Kudo, Hisaaki*; Katsumura, Yosuke*
no journal, ,
Carboxymethyl cellulose (CMC) forms gel at high concentrated solution by irradiation. It seems that polymer radicals, which produced by reactions between OH of water radiolysis products, reacts with each other to form crosslink point. To explain the mechanism of the crosslinking reaction, we investigated the behavior and the position of polymer radicals in irradiated CMC aqueous solution. In the UV absorption spectral measurement after pulse electron beam irradiation, we observed the slow decay of absorbance for about 30 minutes at 10 mM CMC concentration, and confirmed that the initial absorbance was higher with increasing dose. The decay was slower with more concentrated solution and higher molecular weight. Therefore, it seems that the initial yield of polymer radicals is affected by dose and reaction rate is by viscosity of solution. In the ESR measurement after the reaction with OH formed by photolysis of HO, we could estimate the position of CMC radical produced by OH which radical is located on secondary carbon of carboxymethyl substituent on C
.
Saiki, Seiichi; Muroya, Yusa*; Nagasawa, Naotsugu; Tamada, Masao; Kudo, Hisaaki*; Katsumura, Yosuke*
no journal, ,
One kind of polysaccharide derivatives, carboxymethyl cellulose, has a character of good water-solubility and is used in pharmaceutical, food and other industries. In the case of high concentrated carboxymethyl cellulose aqueous solution, cross-linking reactions occur and gels are formed by irradiation, though polysaccharides and their derivatives are generally degraded by irradiation. The purpose of this study is to comprehend the character of macroradicals related to cross-linking reactions. It will help comprehensions of the gelation mechanism of high concentrated carboxymethyl cellulose aqueous solutions by irradiation. Especially, we focused on macroradicals formed by reactions with OH and have tried two measurements, absorbance measurements and ESR. In absorbance measurements, absorbance spectrum decays of carboxymethyl cellulose aqueous solutions were confirmed after irradiation and the decay was very slow. It seemed to show existences of long-lived macroradicals formed by OH. In ESR measurements, we have taken the signal of macroradicals formed by OH, and presumed the structure of macroradicals of carboxymethyl cellulose formed by reactions with OH.
Saiki, Seiichi; Nagasawa, Naotsugu; Tamada, Masao; Kudo, Hisaaki*; Katsumura, Yosuke*
no journal, ,
Carboxymethyl cellulose (CMC) in a concentrated aqueous solution can be radiation-crosslinked, and OH in water radiolysis decomposition is assumed to cause radiation-crosslinking of polymer solutions. The purpose of this study is an indentification of CMC radicals formed by reactions with OH to understand the radiation-crosslinking mechanism of CMC. ESR spectra of CMC radicals formed by OH produced by photolysis of 10 mM hydrogen peroxide were measured in 0.35%CMC aqueous solution. As result, direct observation of CMC radicals in an aqueous solution were succeeded. Radical concentration increases as degree of substitution of carboxymethyl groups increases, and this implies that radicals are located on carboxymethyl groups. If radicals are located on carboxymethyl groups, ESR spectra would show Triplet Doublet, located on carboxymethyl groups linked with C6, and Doublet, located on carboxymethyl groups linked with C2 or C3. Overlapping these spectra at some proportion corresponded to experimental results accurately, and radicals on carboxymethyl groups were presumed from these results.
Saiki, Seiichi; Nagasawa, Naotsugu; Hiroki, Akihiro; Morishita, Norio; Tamada, Masao; Muroya, Yusa*; Kudo, Hisaaki*; Katsumura, Yosuke*
no journal, ,
Polysaccharide derivatives, for example carboxymethyl cellulose (CMC), at a concentrated aqueous solution form gels by irradiation. Radiation-crosslinking mechanism of polysaccharide derivatives is not well known, and polysaccharide radicals formed after ionizing irradiation have not been assigned clearly. The purpose of this study is to observe directly ESR spectrum of CMC radicals in an aqueous solution reacted with OH and to analyze radical sites of CMC radical in detail. It was succeeded to detect CMC radicals in an aqueous solution by ESR using OH radicals from photolysis of hydrogen peroxide (sample: CMC 10 mM / hydrogen peroxide 10 mM). It was identified that a radical on carboxymethyl group linked with C2 and C3 appears as doublet spectrum and that a radical on carboxymethyl group linked with C6 appears as triplet-doublet spectrum from study of hydrogen atom position around the radical and of hyperfine coupling constant.
Saiki, Seiichi; Nagasawa, Naotsugu; Hiroki, Akihiro; Morishita, Norio; Tamada, Masao; Muroya, Yusa*; Kudo, Hisaaki*; Katsumura, Yosuke*
no journal, ,
no abstracts in English
Saiki, Seiichi; Nagasawa, Naotsugu; Hiroki, Akihiro; Morishita, Norio; Tamada, Masao; Muroya, Yusa*; Kudo, Hisaaki*; Katsumura, Yosuke*
no journal, ,
no abstracts in English
-ray irradiation and electron-beam pulse radiolysis study of -carrageenanAbad, L.*; Kudo, Hisaaki*; Saiki, Seiichi; Nagasawa, Naotsugu; Tamada, Masao; Fu, H.*; Muroya, Yusa*; Lin, M.; Katsumura, Yosuke*; Dela Rosa, A. M.*
no journal, ,
The radiation degradation yield of -carrageenan irradiated at atmospheric conditions, in vacuum and at 1% aqueous solutions was determined by GPC. UV-Vis characterization of irradiated -carrageenan for all irradiation conditions indicated a UV-Vis peak at 260nm. The rate constant of reaction of OH radicals with sonicated and irradiated -carrageenan with decreasing molecular weights were determined using e-beam pulse radiolysis.
Saiki, Seiichi; Nagasawa, Naotsugu; Hiroki, Akihiro; Morishita, Norio; Tamada, Masao; Kudo, Hisaaki*; Katsumura, Yosuke*
no journal, ,
Saiki, Seiichi; Muroya, Yusa*; Kudo, Hisaaki*; Nagasawa, Naotsugu; Hiroki, Akihiro; Tamada, Masao; Katsumura, Yosuke*
no journal, ,
no abstracts in English
Saiki, Seiichi; Nagasawa, Naotsugu; Hiroki, Akihiro; Morishita, Norio; Tamada, Masao; Kudo, Hisaaki*; Katsumura, Yosuke*
no journal, ,
no abstracts in English
Saiki, Seiichi; Nagasawa, Naotsugu; Hiroki, Akihiro; Morishita, Norio; Tamada, Masao; Kudo, Hisaaki*; Katsumura, Yosuke*
no journal, ,
no abstracts in English
