High-performance liquid chromatographic analysis of arachidonic acid metabolites by pre-column derivatization using 9-anthryldiazomethane

Arachidonic acid (AA) metabolites produced by washed human platelets and rat macrophages were analyzed by high-performance liquid chromatography (HPLC) using a pre-column derivatization method. The reagent, 9-anthryldiazomethane, used in this study and AA metabolites derivatized by the reagent were purified by gel permeation chromatography (PG-pak C column), prior to normal-phase HPLC analysis. A sample containing eleven derivatives (12-, 15- and 5-hydroxyeicosatetetraenoic acid, 12-L-heptadecatrienoic acid, leukotriene B4, prostaglandins B2, D2, E2 and F2 alpha, thromboxane B2 and 6-keto-prostaglandin F1 alpha) was separated on a normal-phase column (PG-pak B); the detection limit is better than 100 pg for all components.     

Efficient and practical method for synthesizing optically active indan-2-ols by the Ti(O-i-Pr)(4)/2 i-PrMgCl-mediated metalative Reppe reaction

An efficient and practical synthesis of optically active indan-2-ols 1 has been developed starting from readily accessible optically active 4-siloxy-1,6-alkadiynes 2 and ethynyl p-tolyl sulfone, where the metalative Reppe reaction mediated by an economical divalent titanium reagent, Ti(O-i-Pr)(4)/2 i-PrMgCl, is a key step.     

Pyrimidines. 65. Synthesis of 6-substituted thieno[2,3-d]pyrimidine-2,4(1H,3H)-diones

Several 6-substituted thieno[2,3-d]pyrimidine-2,4(1H,3H)-dione derivatives were synthesized. 6-Ethoxycarbonyl derivatives 3 and 7 were prepared by treatment of 6-chloro-5-formyluracil 1 and 6-chloro-5-cyanouracil 6 with ethyl 2-mercaptoacetate in the presence of a base. Electrophilic substitution reactions (Vilsmeier-Haack reaction, bromination, and nitration) of 5,6-unsubstituted thieno[2,3-d]pyrimidine 9 , prepared by condensation of 6-mercaptouracil 8 with chloroacetaldehyde, afforded the corresponding 6-formyl-, 6-bromo-, and 6-nitrothieno[2,3-d]pyrimidines 10, 15 and 16 , respectively.     

High-pressure synthesis of BaVO3: A new cubic perovskite

A new cubic perovskite BaVO₃ was synthesized by high-pressure synthesis at 15 GPa, and 1350 °C. Contrary to our expectations that lattice expansion by Ba substitution for Sr would lead to non-centrosymmetric tetragonal distortion, BaVO₃ preserved its cubic crystal structure with a=3.94288(3) Å at room temperature and had Fermi-liquid characteristics as SrVO₃ down to the lowest temperature.     

Entropy Generation Analysis in Turbulent Reacting Flows and Near Wall: A Review

This paper provides a review of different contributions dedicated thus far to entropy generation analysis (EGA) in turbulent combustion systems. We account for various parametric studies that include wall boundedness, flow operating conditions, combustion regimes, fuels/alternative fuels and application geometries. Special attention is paid to experimental and numerical modeling works along with selected applications. First, the difficulties of performing comprehensive experiments that may support the understanding of entropy generation phenomena are outlined. Together with practical applications, the lumped approach to calculate the total entropy generation rate is presented. Apart from direct numerical simulation, numerical modeling approaches are described within the continuum formulation in the framework of non-equilibrium thermodynamics. Considering the entropy transport equations in both Reynolds-averaged Navier–Stokes and large eddy simulation modeling, different modeling degrees of the entropy production terms are presented and discussed. Finally, exemplary investigations and validation cases going from generic or/and canonical configurations to practical configurations, such as internal combustion engines, gas turbines and power plants, are reported. Thereby, the areas for future research in the development of EGA for enabling efficient combustion systems are highlighted. Since EGA is known as a promising tool for optimization of combustion systems, this aspect is highlighted in this work.     

Determination of cadmium in spring water by graphite-furnace atomic absorption spectrometry after coprecipitation with ytterbium hydroxide.

A coprecipitation method with ytterbium hydroxide was studied for the determination of cadmium in water samples by graphite-furnace atomic absorption spectrometry. Up to 40 ng of cadmium in water samples was quantitatively coprecipitated with ytterbium hydroxide at pH 8.0-11.2. The concentration factor was 100 fold. The coprecipitated cadmium was sensitively determined without any influence of ytterbium and the calibration curve was linear from 0.1 to 4 ng/mL of cadmium. The detection limit (signal/noise = 2) was 2.9 pg/mL in 100 mL of the initial sample solution. Twenty-nine diverse ions tested did not interfere with the determination in at least a 10000-fold mass ratio to cadmium. The proposed method was successfully applied to the determination of cadmium in spring water.     

Stabilized epitaxial films of hexagonal Ni1−xS on MgO(001)

This study used molecular beam epitaxy to prepare epitaxial Ni_1−xS films with NiAs-type structures on MgO(001) substrates. The films were characterized using X-ray diffraction method. Nickel vacancies showed an ordered arrangement of alternating metal-rich and metal-deficient layers along the c-axis. The orientations of epitaxial films were (001) [1,−1,0]Ni_1−xS||(001)[110]MgO and its equivalents because of the coexistence of the trigonal axis of the Ni_1−xS film and the four-fold rotation axis of the MgO substrate. Film compositions were obtained using intensity ratios between 0 0 1 and 0 0 2 reflections and EPMA results. They were dependent on substrate temperature. The relation between lattice parameters and the composition, as determined by the intensity ratio, nearly agrees with that of previously reported bulk Ni_1−xS. The films were stable at room temperature after 1 year, which contrasts with deterioration of bulk Ni_1−xS. This paper presents SEM and RHEED assessments of the film's morphology and structure.     

Decarboxylative radical addition of N-Boc-amino acids to acrylonitrile via photoinduced electron transfer using 1,4-dicyanonaphthalene

Decarboxylative radical addition of N-(t-butoxycarbonyl)amino acids to acrylonitrile was achieved by excitation of 1,4-dicyanonaphthalene. The photochemical decarboxylation was highly dependent on the dicyanoarenes used as electron acceptors and on addition of a base. The photoreaction proceeded smoothly to yield the decarboxylative adduct even in the presence of only a catalytic amount of 1,4-dicyanonaphthalene.     

The effect of the addition of polypropylene-grafted SiO2 nanoparticle on the thermal conductivity of isotactic polypropylene

The thermal conductivity of Isotactic polypropylene (iPP)/silica particle (SiO₂, 26 nm) nanocomposite has been investigated. The untreated SiO₂ and iPP grafted onto SiO₂ were dispersed in the iPP (M _w = 2.5 × 10⁵) matrix. The molecular mass of the iPP-grafted chain, M _n, was precisely controlled to be 5.8 × 10³, 1.2 × 10⁴, and 4.6 × 10⁴. It was found that the thermal conductivities of graft-treated nanocomposites were higher than that of untreated SiO₂ composites. This implied that it is possible to achieve even higher thermal conductivity using the graft treatment. A thermal conductivity analysis conducted using a three-phase model, with considerations for thermal conductivity at interfacial layers, showed that the thermal conductivity of the interfacial layer increased significantly when a graft chain was incorporated. Moreover, the thermal conductivity per graft chain was proportional to the 1/2 power of the molecular mass ( \( M_{\text{n}}^{0.5} \) ). The results strongly suggest that the thermal conductivity pathway of interfacial layer was the main chain direction of iPP-grafted molecular chains.