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51.
The spectral features of the squarylium near-infrared (NIR) dye NN525 in different solutions and its complexation with several metal ions were investigated. The absorbance maximum of the dye is λ=663 nm in methanol. This value matches the output of a commercially available laser diode (650 nm), thus making use of such a source practical for excitation. The emission wavelength of the dye in methanol is λem=670 nm. The addition of either Fe(III) ion or Co(II) ion resulted in fluorescence quenching of the dye. The Stern–Volmer quenching constant, KSV, was calculated from the Stern–Volmer plot to be KSV=2.70×107 M−1 for Co(II) ion. The KSV value for Fe(III) ion could not be established due to the non-linearity of the Stern–Volmer plot and the modified Stern–Volmer plot for this ion. The detection limit is 6.24×10−8 M for Fe(III) ion and 1.55×10−5 M for Co(III) ion. The molar ratio of the metal to the dye was established to be 1:1 for both metal ions. The stability constant, KS, of the metal–dye complex was calculated to be 3.14×106 M−1 for the Fe–dye complex and 2.64×105 M−1 for the Co–dye complex. 相似文献
52.
T. Ogasawara A. Nara H. Okabayashi E. Nishio C. J. O'Connor 《Colloid and polymer science》2000,278(10):946-953
The polymerization behavior of perfluorooctyltrimethoxysilane (PFOS) in ethanol, which is acid-catalyzed by 0.25 M HCl, has
been examined using time-resolved near-IR and 2D near-IR correlation spectra. In the time-resolved near-IR spectra, the bands
at 5164 and 4825 cm−1 have been assigned to the combination bands of water and ethanol OH groups, respectively. It has been found that the absorbance
variation of the two near-IR bands occurs in a two-step process. The absorbance of the 5164 cm−1 band rapidly decreases in the initial step but increases exponentially in the second step, while that of the 4825 cm−1 band rapidly increases both in the initial step and, exponentially, in the second step. These results indicate that the time-dependent
absorbance variation of the two near-IR bands reflects the polymerization process of PFOS, in which consumption and release
of water molecules and release of methanol in the two-step process occur as a consequence of the acid-catalyzed hydrolysis
of methoxy groups and the formation of silanols (SiOH) to form a siloxane bond. It has also been found that this polymerization
process is distinctly reflected in the 2D near-IR correlation spectra.
Received: 23 November 1999/Received in Revised form: 23 February 2000/Accepted 4 March 2000 相似文献
53.
Akira Ohnishi Yuichi Hirata Yasushi Nara Shoji Shinmura Yoshinori Akaishi 《Nuclear Physics A》2000,670(1-4):297-300
We analyze the invariant mass spectrum of Λ-Λ in 12C(K−, K+ ΛΛ) reaction at PK− = 1.65 GeV/c by using a combined framework of IntraNuclear Cascade (INC) model and the correlation function technique. The observed enhancement at low-invariant masses can be well reproduced with attractive Λ-Λ interactions with the scattering length either in the range a = −6 −4 fm (no bound state) or a = 7 12 fm (with bound state). We also discuss Λ-Λ correlation functions in central relativistic heavy-ion collisions as a possible way to eliminate this discrete ambiguity. 相似文献
54.
55.
Regina Sibgatullina Katsumasa Fujiki Takefumi Murase Takahiro Yamamoto Taiji Shimoda Almira Kurbangalieva Katsunori Tanaka 《Tetrahedron letters》2017,58(20):1929-1933
One pot double click strategy containing strain-promoted click-reaction followed by 6π-azaelectrocyclization (RIKEN click reaction) has worked well in the synthesis of multivalent homogeneous and heterogeneous N-glycoalbumins. We have slightly changed the structure of linker unsaturated aldehyde used in this method. As a result it can be easily synthesized from commercially available material and furthermore, the enhancement of its reactivity towards both click-reactions was observed. The data described in this Communications facilitate the usage of the double click strategy as a general method for the synthesis of a variety of neo-N-glycoproteins. 相似文献
56.
Jiří Málek Takefumi Mitsuhashi Naoki Ohashi Yuki Taniguchi Hitoshi Kawaji Tooru Atake 《The Journal of chemical thermodynamics》2011,43(3):405-409
The heat capacity of polycrystalline germanium disulfide α-GeS2 has been measured by relaxation calorimetry, adiabatic calorimetry, DSC and heat flux calorimetry from T = (2 to 1240) K. Values of the molar heat capacity, standard molar entropy and standard molar enthalpy are 66.191 J · K?1 · mol?1, 87.935 J · K?1 · mol?1 and 12.642 kJ · mol?1. The temperature of fusion and its enthalpy change are 1116 K and 23 kJ · mol?1, respectively. The thermodynamic functions of α-GeS2 were calculated over the range (0 ? T/K ? 1250). 相似文献
57.
Trisubstituted oxirane 1 was regiospecifically opened with LiCN in situ prepared from acetone cyanohydrin and LiH to provide the corresponding β-hydroxy nitrile 2 in satisfactory yield, enabling us to manufacture a key intermediate for a new antifungal agent on a multi-kg scale. Some applications of this method to the ring opening of other oxiranes and nucleophilic substitution are also described. 相似文献
58.
The thermal degradation mechanism of tetrabrominated epoxy resin was investigated in order to explain its flame retardant mechanism. From the results obtained it was concluded that the flame retardant mechanisms are 1) a lowering of temperature through degradation and 2) the formation of hydrogen bromide and its role in catalysis in the condensation reaction of the resin. These mechanisms were investigated by the pyrolysis behavior of the resin by gas chromatography, thermal gravimetric analysis, and differential thermal analysis studies. 相似文献
59.
Yoshifumi Takeda Nara 《Mathematische Nachrichten》1994,167(1):313-329
Let X be a nonsingular relatively minimal projective surface over an algebraically closed field of characteristic p > 0. We call X a false hyperelliptic surface if X satisfies the following conditions: (1) c2(X) = 0, c1(X)2 = 0, dim Alb (X) = 1, and (2) All fibres of the Albanese mapping of X are rational curves with only one cusp of type xpv + yn = 0. In this article, we consider a false hyperelliptic surface whose Albanese mapping has a cross-section. We prove that every false hyperellyptic surface with section arises from an elliptic ruled surface and that every false hyperelliptic surface has an elliptic fibration with multiple fibre. Moreover, we construct an example of false hyperelliptic surface with section, whose elliptic fibration has a multiple fibre of supersingular elliptic curve of multiplicity pv (v > 1). 相似文献
60.
Yoshiyama H Shibata N Sato T Nakamura S Toru T 《Chemical communications (Cambridge, England)》2008,(17):1977-1979
A genuine example of non-aggregated highly fluorescent binuclear phthalocyanines is reported; spectroscopic studies and computations revealed that the two halves of trifluoroethoxy-coated binuclear phthalocyanine are rotated in the same directions so as to contact each other as much as possible. 相似文献