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41.
Sequential injection analysis (SIA) with lab-at-valve (LAV) approach for on-line liquid-liquid micro-extraction has been exploited. Sample, reagent and organic solvent were sequentially aspirated into a coil attached to a central port of a conventional multiposition selection valve, where the extraction process was performed. The aqueous and organic phases were separated in a conical separating chamber LAV unit attached at one port of the valve. The organic phase containing extracted product was then monitored spectrophotometrically. The system offers a novel alternative on-line automated extraction in a micro-scale and has been successfully demonstrated for the assays of diphenhydramine hydrochloride (DPHH) in pharmaceutical preparations and anionic surfactant in water samples. 相似文献
42.
Chimnoi N Pisutjaroenpong S Ngiwsara L Dechtrirut D Chokchaichamnankit D Khunnawutmanotham N Mahidol C Techasakul S 《Natural product research》2008,22(14):1249-1256
A new labdane diterpenoid, (E)-labda-8(17),12-dien-15,16-olide (1) together with eight known compounds, coronarin D (2), coronarin D methyl ether (3), coronarin D ethyl ether (4), isocoronarin D (5), coronarin B (6), labda-8(17),11,13-trien-15,16-olide (7), (E)-labda-8(17),12-diene-15,16-dial (8) and 16-hydroxylabda-8(17),11,13-trien-15,16-olide (9), are isolated from the rhizomes of Hedychium coronarium. Compounds 2-4, 5 and 9 are isolated as mixtures of C-15, C-14 and C-16 epimers, respectively. Their structures are determined on the basis of their spectroscopic data. The epimeric mixtures of 2 and 3 have not been reported before. Some of them were evaluated for their cytotoxicity. 相似文献
43.
Settheeworrarit T Hartwell SK Lapanatnoppakhun S Jakmunee J Christian GD Grudpan K 《Talanta》2005,68(2):262-267
Guava leaf extract is utilized as an alternative natural reagent for quantification of iron. The flow injection technique enables the use of the extract in acetate buffer solution without the need of further purification. Some properties of the extract such as its stability and ability to form a colored complex with iron were studied. The proposed system is an environmentally friendly method for determination of iron with less toxic chemical wastes. 相似文献
44.
Arrak Klinbumrung Anukorn Phuruangrat Titipun Thongtem Somchai Thongtem 《Russian Journal of Inorganic Chemistry》2018,63(6):725-731
BaMoO4 crystals were synthesized by a 900 W microwave induced plasma process (MIP) for 40, 60, 120 and 140 min. Phase, morphology, vibrational mode and energy gap were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy, Fourier transform infrared (FTIR) spectroscopy and UV-visible spectroscopy. In this research, the phase and morphology of product were influenced by microwave heating time. The sample processed for 140 min shows spherical particles tetragonal BaMoO4 phase with size of 200–700 nm in diameter. BaMoO4 with band gap of 3.35 eV shows a blue emission wavelength at 440 nm. 相似文献
45.
46.
Patcharanan Junploy Anukorn Phuruangrat Somchai Thongtem Titipun Thongtem 《Research on Chemical Intermediates》2018,44(10):5981-5993
Calcium stannate (CaSnO3) was successfully synthesized in the solutions containing different surfactants by cyclic microwave and calcination combination. Phase, morphology and vibration mode were characterized by X-ray diffraction, field emission scanning electron microscopy and Fourier transform infrared spectroscopy. Growth mechanism of the products was also explained according to the analytical results. Their photocatalytic activities were tested through methylene blue (MB) degradation induced by UV radiation. In the MB solution with pH 6, the S-CTAB product showed the highest decolorization efficiency of 89.1% and the highest rate constant of 4.374?×?10?3 min?1. 相似文献
47.
This paper is a continuation of the authors’ previous work. Two-phase air–water flow experiments are performed in a horizontal circular micro-channel. The test section is made of a fused silica tube with an inner diameter of 0.15 mm and a length of 104 mm. The flow phenomena, which are liquid/unstable annular alternating flow (LUAAF), liquid/annular alternating flow (LAAF), and annular flow, are observed and recorded by a high-speed camera mounted together with a stereozoom microscope. A flow pattern map is presented in terms of the phase superficial velocities and is compared with those of other researchers obtained from different working fluids. Image analysis is performed to determine the void fraction, which increases non-linearly with increasing volumetric quality. It is revealed that the two-phase frictional multiplier data show a dependence on flow pattern rather than mass flux. Based on the present data, a new pressure drop correlation is proposed for practical applications. According to the present study, in general the data for the two-phase air–water flow characteristics are found to comply with those of working fluids other than air–water mixtures. 相似文献
48.
Anukorn Phuruangrat Nuengruethai Ekthammathat Somchai Thongtem Titipun Thongtem 《Research on Chemical Intermediates》2013,39(3):1363-1371
LaPO4 nanowires (NWs) measuring 10–15 nm in diameter and up to 4 μm long were prepared by a 200 °C and 12 h hydrothermal reaction of LaCl3 and Na3PO4·12H2O solution with pH adjusting by 37 % HNO3 to 1, without using any surfactants or templates. The as-prepared LaPO4 NWs were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy, and UV–visible and photoluminescent spectroscopy. In the present research, photonic luminescence and absorbance of LaPO4 NWs show the maximum emission at 397.60 nm in the violet region and a band gap of 2.87 eV. 相似文献
49.
Sulawan Kaowphong Titipun Thongtem Somchai Thongtem 《Russian Journal of Inorganic Chemistry》2010,55(4):577-582
Micro-crystalline PbWO4 was sonochemically produced using Pb(CH3COO)2 · 3H2O and Na2WO4 · 2H2O in aqueous solutions with and without anionic surfactant (sodium dodecyl sulphate or sodium lauryl sulphate). The product
morphologies were influenced by the pH values and the surfactant. Micro-crystalline PbWO4 composing of Pb, W and O, and W-O stretching vibration band of WO4 tetrahedrons were detected using XRD, SEM, EDX, TEM, SAED and FTIR. Photoluminescent intensities, caused by the electronic
transition from 1T2 to 1A1 states, shown to increase with the increase in the pH values of the solutions. 相似文献
50.
Thongboonkerd V Songtawee N Kanlaya R Chutipongtanate S 《Analytical and bioanalytical chemistry》2006,384(4):964-971
There is a need for a simple method that can directly quantify hydrophobic proteins. UV-visible spectrophotometry was applied
in the present study for this purpose. Absorbance at λ=280 nm (A
280) was detected for both Escherichia coli membrane proteins and bovine serum albumin, whereas absorbance at λ=620 nm (A
620) was only detected for E. coli membrane proteins. The A
620 values of the brain samples were greater than those of heart samples when equal concentrations were used, regardless of the
type of solubilizing agent employed. Because hydrophobic proteins tend to form colloidal microparticles in solution, we also
applied UV-visible spectrophotometry to evaluate the efficacies of different extraction protocols for solubilizing hydrophobic
proteins. For brain protein extraction, the highest A
620 was observed in samples recovered using Tris, whereas the lowest was from samples recovered using SDS. Solubilizing brain
tissue with 0.25% SDS (above the CMC) gave a lower A
620 than extraction with 0.025% SDS (below the CMC). Addition of 0.25% SDS to samples recovered with Triton caused A
620 to drop. A
620 could also be used to distinguish between the hydrophobic fractions (pellets) of brain and urine proteins and their hydrophilic
fractions (supernatants) prefractionated using high-speed centrifugation. Additionally, an A
620/A
280 ratio exceeding 0.12 appears to denote highly hydrophobic samples. Our data suggest that direct UV-visible spectrophotometry
can be used as a simple method to quantify and evaluate the solubilities of hydrophobic proteins. 相似文献