Optimisation of thermal lens microscopic measurements in a microchip

The thermal lens optical scheme-design was optimised for microscopic measurements in microchannels. The efficient pathlength of the sample, irradiated volume, and the diameter of the thermal lens were estimated. Experimental time curves of development of the thermal lens and periodical oscillations of the signal due to convectional heat transfer are in good agreement with the theoretically expected behaviour. Noise sources (laser noises, instrumental flicker noise, convection, and flow noise) were studied. The possible effect of probe laser power on transient and steady-state thermal lens measurements were estimated. The effect of solvent absorption on the performance characteristics is shown. Under the optimum optical scheme-design, the limits of detection of ferroin and Sunset Yellow FCF at 488.0 nm are 1×10⁻⁸ and 4×10⁻⁹ mol dm⁻³, respectively (corresponding quantities in the detection volume are 3×10⁻²¹ and 1×10⁻²¹ mol). The total linear calibration range is n×10⁻⁸ to n×10⁻⁴ mol dm⁻³, the repeatability R.S.D. for this range is 3-7%. The optimised instrument was also used for the determination of characteristic rate constants of formation and dissociation of ferroin at the level of n × 10⁻⁸ mol dm⁻³. Some analytical applications are discussed.     

Absolute configuration of chiral [2.2]paracyclophanes with intramolecular charge-transfer interaction. Failure of the exciton chirality method and use of the sector rule applied to the cotton effect of the CT transition

Optically active 4,7-dicyano-12,15-dimethoxy[2.2]paracyclophanes have been separated by chiral HPLC and their absolute configurations determined by comparison of the experimental and the theoretical VCD spectra. X-ray crystallographic structures for both diastereomers are also reported. The electronic circular dichroism spectra of these enantiomeric pairs, as chiral intramolecular charge-transfer complexes, have been obtained for the first time. The exciton coupling method, usually used for determining the absolute configuration of chiral molecules, however, did not give a correct prediction for the present CT-paracyclophane system. Instead, empirical sector rules for the signs of the Cotton effects of the CT transition can be applied for the assignment of the absolute configuration.     

Preparation of functionally Pegylated gold nanoparticles with narrow distribution through autoreduction of auric cation by alpha-biotinyl-PEG-block-[poly(2- (N,N-dimethylamino)ethyl methacrylate)

PEGylated gold nanoparticles with biotin moieties installed at the distal end of the PEG tethered chains were prepared by the autoreduction of HAuCl4 catalyzed by alpha-biotinyl-PEG-block-poly[2-(N,N-dimethylamino)ethyl methacrylate] (biotinyl-PEG/PAMA) in aqueous medium at room temperature. The size of the gold nanoparticles was controllable in a range of 6-13 nm by changing the initial Au3+/polymer ratio, while retaining their narrow size distribution. The dispersion stability of the nanoparticles in aqueous medium was extremely high even under the condition of salt concentration as high as I = 2.0. Biotinyl-PEG/PAMA-anchored gold nanoparticles underwent specific aggregation in the presence of streptavidin, revealing their promising utility as colloidal sensing systems applicable under biological condition.     

Effect of terminal polar substituents on the nature of smectic A liquid crystals of a series of 4-(4'-octyloxybenzoyloxy)benzylidene-4'-substituted anilines

The nature of smectic A liquid crystals and the phase transitions from smectic A to nematic phases are studied in the homologous series of 4-(4'-octyloxy-benzoyloxy)benzylidene-4'-substituted anilines, in which the substituents are H, F, Cl, Br, I, NO₂ and CN. Measurements have been performed for the dipole moment of the molecule, the smectic A lattice period, the temperatures and the entropies of phase transitions, and the temperature dependence of the orientational order parameter, all of which provide information on the intermolecular pair potentials. It is shown that the introduction of a terminal polar substituent brings about counteracting contributions to the stability of the smectic A state. It is suggested that the reentrant nematic phase transition can appear in the strongly polar mesogens if the extent of antiparallel association of the molecules increases on lowering the temperature.     

Photochemistry of N-aryl-2(1H)-pyrimidin-2-ones

Irradiation of N-aryl-2(1H)-pyrimidin-2-ones ($\text{3a}$-$\text{c}$) in a mixed benzene-alcohol solution afforded the products initiated by Type I cleavage, 1-(3-alkoxycarbonylamino-2-propene)-N-arylimines ($\text{4a}$-$\text{c}$, $\text{5}$, and $\text{6}$) in 45–51% yields.     

Photochemical reactions. 133rd Communication. Photochemistry of epoxydienes of the ionone series: Influence of a methyl group at the diene side chain on the oxirane cleavage

On triplet excitation (λ > 280 nm, acetone), the epoxydiene (E)- 2 undergoes (E)/(Z)-isomerization exclusively, leading to the conformers (Z)- 2A and (Z)- 2B . On singlet excitation (λ = 254 nm), apart from (Z)- 2A + B , the cyclobutenes 3A + B are formed. However, the epoxydiene (E)- 2 does not undergo reactions leading to carbene and C,O-bond cleavage products, which are normally observed on singlet and triplet excitation, respectively, of the epoxydienes of the ionone series.     

CO2 and N2O laser Stark spectroscopy of the ν1 band of the ClO2 radical

The ν₁ fundamental band of the ClO₂ radical has been studied by means of the 10.6-μm CO₂ and N₂O laser Stark spectroscopy. More than 250 and 150 Stark resonances were assigned for the ³⁵ClO₂ and ³⁷ClO₂ species, respectively, and were analyzed together with the recent microwave and laser-microwave double resonance results to give molecular constants including spin-rotation interaction constants. The ν₁ band origins and electric dipole moments both in the ground and ν₁ states were determined accurately

     

519.

Chemical processing on microchips for analysis, synthesis, and bioassay   总被引：1，自引：0，他引：1  

Tokeshi M  Kikutani Y  Hibara A  Sato K  Hisamoto H  Kitamori T 《Electrophoresis》2003,24(21):3583-3594

This review describes our recent research on miniaturization of chemical systems. We have developed a miniaturization methodology based on pressure-driven multiphase laminar flow and a highly sensitive detection tool, the thermal lens microscope. Some representative applications of the methodology in the fields of analysis, synthesis, and bioassay are described.     

520.

Formation of β- and β″-Al₂O₃ by the solid state reaction between NaAlO₂ and γ-Al₂O₃     

Takehiko Takahashi  Katsumi Kuwabara 《Journal of solid state chemistry》1979,30(3)

The solid state reaction of NaAlO₂ with γ-Al₂O₃ was investigated kinetically. Powdered compacts with various compositions (Al₂O₃/NaAlO₂ = 1–5) were fired at 700–1200°C for 1–768 hr. The amounts of the reaction product were determined by peak heights of X-ray diffraction patterns. β″-Al₂O₃ was formed predominantly from the sample with Al₂O₃/NaAlO₂ = 2. The firing time for the β″-Al₂O₃ formation was shortened as the firing temperature was raised, and the activation energy, E_a, for formation was about 130–135 kcal/mole. The sample of Al₂O₃/NaAlO₂ = 5 formed m-Al₂O₃ with the mullite structure and was observed to transform gradually to β-Al₂O₃. E_a for the m-Al₂O₃ formation and for the transition were about 55–60 and 40 kcal/mole, respectively, which resulted in E_a of about 95–100 kcal/mole for the β-Al₂O₃ formation. The mechanism of the m-Al₂O₃ formation is discussed briefly.     

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		35ClO2		37ClO2
$\text{ν}{}_0$		945.592 357(60)		939.602 909(66)		cm?1
μ′		1.788 39(13)		1.788 46(15)		D
μ″		1.791 95(10)		1.792 10(13)		D
δμ		?0.003 56(18)		?0.003 64(26)		D

Chemical processing on microchips for analysis, synthesis, and bioassay

This review describes our recent research on miniaturization of chemical systems. We have developed a miniaturization methodology based on pressure-driven multiphase laminar flow and a highly sensitive detection tool, the thermal lens microscope. Some representative applications of the methodology in the fields of analysis, synthesis, and bioassay are described.     

Formation of β- and β″-Al2O3 by the solid state reaction between NaAlO2 and γ-Al2O3

The solid state reaction of NaAlO₂ with γ-Al₂O₃ was investigated kinetically. Powdered compacts with various compositions (Al₂O₃/NaAlO₂ = 1–5) were fired at 700–1200°C for 1–768 hr. The amounts of the reaction product were determined by peak heights of X-ray diffraction patterns. β″-Al₂O₃ was formed predominantly from the sample with Al₂O₃/NaAlO₂ = 2. The firing time for the β″-Al₂O₃ formation was shortened as the firing temperature was raised, and the activation energy, E_a, for formation was about 130–135 kcal/mole. The sample of Al₂O₃/NaAlO₂ = 5 formed m-Al₂O₃ with the mullite structure and was observed to transform gradually to β-Al₂O₃. E_a for the m-Al₂O₃ formation and for the transition were about 55–60 and 40 kcal/mole, respectively, which resulted in E_a of about 95–100 kcal/mole for the β-Al₂O₃ formation. The mechanism of the m-Al₂O₃ formation is discussed briefly.