Labdane diterpenes from the rhizomes of Hedychium coronarium

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.     

Effect of surfactants on phase,crystal growth and photocatalysis of calcium stannate synthesized by cyclic microwave and calcination combination

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.     

An experimental investigation of two-phase air–water flow through a horizontal circular micro-channel

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.     

Preparation of LaPO4 nanowires with high aspect ratio by a facile hydrothermal method and their photoluminescence

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.     

Characterization of micro-crystalline lead tungstate with different morphologies produced by the sonochemical process

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.     

Quantitative analysis and evaluation of the solubility of hydrophobic proteins recovered from brain, heart and urine using UV-visible spectrophotometry

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.     

Analysis of lead molybdate and lead tungstate synthesized by a sonochemical method

Lead molybdate and lead tungstate nanoparticles were successfully synthesized by a sonochemical method for 1 h. XRD patterns showed the body-centered tetragonal structures of PbMoO₄ and PbWO₄, and were in accordance with those of the simulation and JCPDS software. Calculated lattice parameters are a = b = 5.4233 Å and c = 12.1253 Å for PbMoO₄, and 5.4570 Å and 12.0995 Å for PbWO₄. They are in accordance with those of the corresponding JCPDS software. TEM images show that the particles were 29.09 ± 5.22 nm and 21.05 ± 2.68 nm for PbMoO₄ and PbWO₄, respectively. Raman and FTIR vibrations were investigated to identify a definite existence of the structures.     

Thermal conductivity of Al2O3/water nanofluids

A considerable number of studies can be found on the thermal conductivity of nanofluids in which Al₂O₃ nanoparticles are used as additives. In the present study, the aim is to measure the thermal conductivity of very narrow Al₂O₃ nanoparticles with the size of 5 nm suspended in water. The thermal conductivity of nanofluids with concentrations up to 5 % is measured in a temperature range between 26 and 55 °C. Using the experimental data, a correlation is presented as a function of the temperature and volume fraction of nanoparticles. Finally, a sensitivity analysis is performed to assess the sensitivity of thermal conductivity of nanofluids to increase the particle loading at different temperatures. The sensitivity analysis reveals that at a given concentration, the sensitivity of thermal conductivity to particle loading increases when the temperature increases.     

Simple bead injection-flow injection system for the determination of copper.

We demonstrate the extended application of a simple bead injection-flow injection system with a modified simple colorimetric detection unit for the determination of low amount of Cu2+ in samples of different matrices (water and supplement tablet samples) with minimal sample pretreatment by employing ammonium pyrrolidinedithiocarbamate (APDC) reagent.