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排序方式: 共有163条查询结果,搜索用时 19 毫秒
141.
Joh Alfa 《Analytical and bioanalytical chemistry》1902,41(9):560-561
142.
Dong-Yong Chung Heui-Seung Seo Jae-Won Lee Han-Beom Yang Eil-Hee Lee Kwang-Wook Kim 《Journal of Radioanalytical and Nuclear Chemistry》2010,284(1):123-129
A feasibility and basic study to find a possibility to develop such a process for recovering U alone from spent fuel by using
the methods of an oxidative leaching and a precipitation of U in high alkaline carbonate media was newly suggested with the
characteristics of a highly enhanced proliferation-resistance and more environmental friendliness. This study has focused
on the examination of an oxidative leaching of uranium from SIMFUEL powders contained 16 elements (U, Ce, Gd, La, Nd, Pr,
Sm, Eu, Y, Mo, Pd, Ru, Zr, Ba, Sr, and Te) using a Na2CO3 solution with hydrogen peroxide. U3O8 was dissolved more rapidly than UO2 in a carbonate solution. However, in the presence of H2O2, we can find out that the leaching rates of the reduced SIMFUEL powder are faster than the oxidized SIMFUEL powder. In carbonate
solutions with hydrogen peroxide, uranium oxides were dissolved in the form of uranyl peroxo-carbonato complexes. UO2(O2)
x
(CO3)
y
2−2x−2y
, where x/y has 1/2, 2/1. 相似文献
143.
Kwang-Wook Kim Jae-Won Lee Dong-Young Chung Eil-Hee Lee Kweon-Ho Kang Kune-Woo Lee Kee-Chan Song Myung-June Yoo Geun-Il Park Jei-Kwon Moon 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(2):909-916
This work studied a way to reclaim uranium from contaminated UO2 oxide scraps as a sinterable UO2 powder for UO2 fuel pellet fabrication, which included a dissolution of the uranium oxide scraps in a carbonate solution with hydrogen peroxide
and a UO4 precipitation step. Dissolution characteristics of reduced and oxidized uranium oxides were evaluated in a carbonate solution
with hydrogen peroxide, and the UO4 precipitation were confirmed by acidification of uranyl peroxo–carbonate complex solution. An agglomerated UO4 powder obtained by the dissolution and precipitation of uranium in the carbonate solution could not be pulverized into fine
UO2 powder by the OREOX process, because of submicron-sized individual UO4 particles forming the agglomerated UO4 precipitate. The UO2 powder prepared from the UO4 precipitate could meet the UO2 powder specifications for UO2 fuel pellet fabrication by a series of steps such as dehydration of UO4 precipitate, reduction, and milling. The sinterability of the reclaimed UO2 powder for fuel pellet fabrication was improved by adding virgin UO2 powder in the reclaimed UO2 powder. A process to reclaim the contaminated uranium scraps as UO2 fuel powder using a carbonate solution was finally suggested. 相似文献
144.
Yasushi Joh Yahide Kotake Toshio Yoshihara Fumio Ide Kazuo Nakatsuka 《Journal of polymer science. Part A, Polymer chemistry》1967,5(3):593-603
Methacrylonitrile (MAN) was polymerized with diethylmagnesium. Acetone-insoluble portions of the polymers are found to be crystalline. Highly crystalline portions can be isolated by further extraction of the acetone-insoluble parts with dimethylformamide (DMF). A film of DMF-insoluble fraction can be oriented uniaxially by hot-press rolling. The crystalline PMAN is insoluble in the usual solvents for amorphous PMAN because of their crystallinity and is easily soluble in CF3COOH or Cl2CHCOOH. The viscosity–molecular weight relationship was determined in Cl2CHCOOH at 30°C. as [η] = 3.24 × 10?3M0.520. We found several crystalline bands in the infrared spectra, for example, at 1192 and 885 cm.?1. Formation of the carbonyl group in the polymer is discussed, and it is concluded that it may be formed by the hydrolysis of conjugated cyclic imine or hydrolysis of the nitrile group in the polymer to acid amide. 相似文献
145.
Seo HR Kwan YW Cho CK Bae S Lee SJ Soh JW Chung HY Lee YS 《Experimental & molecular medicine》2004,36(4):292-299
Epidermal keratinocyte differentiation is a tightly regulated stepwise process that requires protein kinase C (PKC) activation. Studies on cultured mouse keraitnocytes induced to differentiate with Ca2+ have indirectly implicated the involvement of PKCa isoform. When PKCalpha was overexpressed in undifferentiated keratinocytes using adenoviral system, expressions of differentiation markers such as loricrin, filaggrin, keratin 1 (MK1) and keratin 10 (MK10) were increased, and ERK1/2 phosphorylation was concurrently induced without change of other MAPK such as p38 MAPK and JNK1/2. Similarly, transfection of PKCalpha kinase active mutant (PKCalpha- CAT) in the undifferentiated keratinocyte, but not PKCbeta-CAT, also increased differentiation marker expressions. On the other hand, PKCalpha dominant negative mutant (PKCbeta-KR) reduced Ca2+ -mediated differentiation marker expressions, while PKCbeta-KR did not, suggesting that PKCalpha is responsible for keratinocyte differentiation. When downstream pathway of PKCalpha in Ca2+ -mediated differentiation was examined, ERK1/2, p38 MAPK and JNK1/2 phosphorylations were increased by Ca2+ shift. Treatment of keratinocytes with PD98059, MEK inhibitor, and SB20358, p38 MAPK inhibitor, before Ca2+ shift induced morphological changes and reduced expressions of differentiation markers, but treatment with SP60012, JNK1/2 inhibitor, did not change at all. Dominant negative mutants of ERK1/2 and p38 MAPK also inhibited the expressions of differentiation marker expressions in Ca2+ shifted cells. The above results indicate that both ERK1/2 and p38 MAPK may be involved in Ca2+ -mediated differentiation, and that only ERK1/2 pathway is specific for PKCalpha-mediated differentiation in mouse keratinocytes. 相似文献
146.
Yasushi Joh 《Journal of polymer science. Part A, Polymer chemistry》1979,17(12):4051-4067
Amorphous polyacrylonitrile was successfully synthesized with bis(pentamethyleneimino)magnesium in heptane at 70°C. The amorphousness of the polymer increased with rising polymerization temperature and was favored by the nonpolar solvent. The polymer showed regular head-to-tail sequences which were confirmed by converting the polymer into polyacrylic acid and polymethylacrylate. The amorphous PAN produced a broad x-ray diagram with a maximum at 2θ = 16.1° and a less intense halo at 2θ = 27.5°. This pattern did not change after heat treatment. The synthesis of amorphous PAN strongly supports Imai's hypothesis that polyacrylonitrile consists of paracrystalline and amorphous phases. The amorphous PAN also tends to support Minami's assignment of the two absorptions in the temperature dependence of the dynamic loss tangent; the absorption at the lower temperature (110°C) is due to molecular motions in the paracrystalline phase and the absorption at the higher temperature (160°C) is attributed to the molecular motions in the amorphous region. 相似文献
147.
148.
Joh F. Ehlers 《Colloid and polymer science》1953,131(3):137-145
Zusammenfassung Ausgehend von der Formulierung der Alkoholbildung aus Phenol und Formaldehyd als Ionenreaktion, der Ionenbildung der Alkohole
in Anlehnung an K.Hultzsch und der Bildung von Harzbasen als wesentlicher Bestandteile des Natrium-Phenol-Resols werden im
Gegensatz zu den aus Kettenmolekülen der Mehrkern-Phenole bestehenden Novolaken die Resole als Kationen einseitig zu „Igel-Molekülen“
zusammengefa\ter Alkohole des Phenols oder von Mehrkern-Phenolen dargestellt. Beim Natrium-Phenol-Resol bildet die endst?ndige
Alkoholgruppe in o-Stellung zum Phenol-Hydroxyl wegen der Wasserstoff brücke komplexe Kationen um Natrium als Zentralatom,
in denen 6 Phenolmoleküle oder Kettenmoleküle der Mehrkernphenole 6-strahlig zusammengefa\t sind.
Beim Ammoniak-Phenol-Resol kann statt einer Fassung zum komplexen Kation die Bindung der Phenole, die endst?ndige Phenole
in Kettenmolekülen sein k?nnen, über Methylenbrücken an je ein Stickstoffatom im N-CH2-ring oder gemeinsam an ein dreifach funktionelles Stickstoffatom erwartet werden.
Die Darstellung der Harzbildung ist nicht nur in übereinstimmung mit den bisher bekannten Ergebnissen der Forschung, sie vermag
auch bisher nicht erkl?rliche Beobachtungen zu deuten. Sie begründet den kugeligen Bau der Moleküle in den Resolen, sie erkl?rt
die Reaktion von vornehmlich p-Oxybenzylalkohol in saurem Medium, die Bildung von vornehmlich o-Oxybenzylalkohol mit steigendem
Gehalt an Natriumhydroxyd, das Fehlen von o-o′-Dioxy-diphenylmethan in technischen Harzen, das überwiegen von p-p′-über o-p′-Dioxy-diphenyl-methan
in sauer hergestellten Harzen und die optimale Harzbildung bei mittlerem Hydroxyd-Gehalt und begründet Beobachtungen bei der
praktischen Anwendung von Resolen, wie aus dem Beispiel der Verleimung von Metall mit Natrium-Phenol-Resol hervorgeht. 相似文献
149.
Sungho Lee Yang-Jin Kim Do-Hwan Kim Bon-Cheol Ku Han-Ik Joh 《Journal of Physics and Chemistry of Solids》2012,73(6):741-743
Graphene oxide (GO) was prepared from graphite using a modified Hummers method. The GO dispersed in dimethyl sulfoxide (DMSO) was incorporated into polyacrylonitrile (PAN) dissolved in DMSO to prepare composite films using a conventional solution-casting method. DSC results showed a significant decrease in the cyclization temperature of polyacrylonitrile (PAN) in the presence of GO because the functional groups of GO initiated cyclization at lower temperature by an ionic mechanism. Heat treatment in air at 250 °C for 3 h led to stabilization of PAN and a simultaneous partial reduction of GO. A significant decrease in the electrical resistivity of the GO/PAN composite films was observed because the partially reduced GO acted as a conducting filler. 相似文献
150.
In this study, we developed a fabrication method of conductive and transparent Ag mesh electrodes on flexible polymer film at temperatures lower than 100?°C. Random patterned Ag mesh film was fabricated on a flexible PET substrate over 15?×?15?cm2 by a self-assembly process. It became conductive by a coupling process at low temperatures. The coupled Ag mesh film showed more than 88% transmittance in visible wavelength and less than 8.2?Ω?sq?1 in sheet resistance with figure of merit (FoM) value of 350. This transparent flexible EMI shield film fabricated with a coupled Ag mesh pattern showed high EM shielding effectiveness of ?23?dB?at 1.5–10?GHz frequency with a high transparency of 88%. 相似文献