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《Tetrahedron》1959,6(4):304-311
Anhydrobiisatic acid (IVa), a new type of compound containing the phenhomazine ring system, has been obtained by self-condensation of isatic acid—(o-aminophenyl)glyoxylic acid—. The structure of this acid has been established and derivatives have been prepared. N:N′-Dimethylanhydrobiisatic acid (IVc) has been resolved into optically active components. 相似文献
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Gordon J.F. Chittenden 《Tetrahedron letters》1981,22(45):4529-4532
Treatment of galactitol uith 2,2-dimethoxypropane in dimethylsulphoxide unexpeatedly yields the title triketal, containing a cis-dioxolane ring; the structure of the product has been confirmed by spectral measurements. 相似文献
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WANG Miao WANG Rui XU Yan-Ling YANG Chun-Hui XU Yu-Heng SHI Lian-Sheng 《结构化学》2007,26(10):1218-1222
In:Fe:Mn:LiNbO3(LN) crystals were grown in air atmosphere by Czochralski method with different concentration of In (0,1,2,3 mol%) in the melts,while the contents of Fe2O3 and MnO were 0.1 and 0.5 mol%,respectively. The location of doping ions was analyzed by Ultraviolet-visible absorption spectra and differential thermal analysis. The diffraction efficiency (η),writing time (τw) and erasure time (τe) of the crystals were measured by two-beam coupling experiment. The dynamic range and photorefractive sensitivity have also been calculated. The results showed that with the increase of In ions in the melt,the absorption edge of In:Fe:Mn:LN crystal shifts to the violet firstly and then makes the Einstein shift,the Curie temperature of crystal increases firstly and then decreases,the storage ratio speeds up,diffraction efficiency decreases,and dynamic range and photorefractive sensitivity increase. The mechanism of holographic storage properties of In:Fe: Mn:LN crystal with different doping concentration of In3+ was investigated,suggesting the In: Fe:Mn:LN crystals are excellent holographic storage materiel with better synthetical properties than Fe:Mn:LN crystals. 相似文献
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Sreekanth Dittakavi Lavanya Mahadevan Devaraj V. Chandrashekar Ravi Kanth Bhamidipati Juluri Suresh Saravanakumar Dhakshinamoorthy Ziyu Li Felix Baerenz Norbert Tennagels Ramesh Mullangi 《Biomedical chromatography : BMC》2020,34(5):e4790-i
Ceramides are known to be involved in various biological processes with their physiological levels elevated in various disease conditions such as diabetes, Alzheimer's, atherosclerosis. To facilitate the rapid screening of Cer d18:1/16:0, d18:1/24:0, d18:1/24:1, d18:1/18:0, d18:1/14:0, d18:1/20:0, and d18:1/22:0 inhibition in HepG2 cells, a RapidFire coupled to tandem mass spectrometry (RF–MS/MS) method has been developed. The RF platform provides an automated solid-phase extraction system that gave a throughput of 12.6 s per sample to an MS/MS system using electrospray ionization under the positive ion mode. Chromatographic separation of Cer d18:1/16:0, d18:1/24:0, d18:1/24:1, d18:1/18:0, d18:1/14:0, d18:1/20:0, and d18:1/22:0 was achieved using a ternary gradient on C8 type E cartridge. The MS/MS ion transitions monitored were 538.2 → 264.2, 650.7 → 264.2, 648.6 → 264.2, 566.4 → 264.2, 510.4 → 264.2, 594.4 → 264.2, 622.5 → 264.2, and 552.3 → 250.2 for Cer d18:1/16:0, d18:1/24:0, d18:1/24:1, d18:1/18:0, d18:1/14:0, d18:1/20:0, d18:1/22:0, and the internal standard (Cer d17:1/18:0), respectively. The RF–MS/MS methodology showed an excellent performance with an average Z′ value of 0.5–0.7. This is the first report of an RF–MS/MS assay for screening of ceramides which is amenable for high-throughput screening. 相似文献
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The mass-spectra of 1:12, 2:3, 4:5, 6:7, 8:9, 10:11-hexabenzocoronene and the isomer 1:2, 3:4, 5:6, 7:8, 9:10, 11:12-hexabenzocoronene have been examined. The former is typically that of an aromatic conjugated hydrocarbon and is sparse, the latter is more intense. It is conjectured that the former may be found in interstellar space. 相似文献
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A.V. Vasin Y. Ishikawa S.P. Kolesnik A.A. Konchits V.S. Lysenko A.N. Nazarov G.Yu. Rudko 《Solid State Sciences》2009,11(10):1833-1837
Amorphous hydrogenated carbon-rich silicon–carbon alloy film (a-Si0.3C0.7:H) was deposited by reactive dc-magnetron sputtering of silicon target in argon–methane gas mixture. As-deposited film exhibits white photoluminescence at room temperature. After the deposition the samples were thermally annealed in dry Ar, wet Ar, or dry O2 flow at 450 °C for 30 minutes that resulted in the enhancement of the photoluminescence intensity by a factor of about 5, 8 and 12 respectively. Spectral distribution of light emission was almost unchanged at the annealing in dry and wet argon while the oxidation in pure oxygen resulted in strong enhancement of a “blue” shoulder in the spectrum. EPR measurements at room temperature showed the decrease of spin concentration after thermal treatment in dry and wet argon and no EPR signal was detected after annealing in oxygen. FTIR and XPS measurements evidenced the formation of a-Si:O:C:H composite material after dry oxidation. Based on the measurements of photoluminescence in the temperature range 7–300 K it is suggested that light-emitting efficiency of a-Si0.3C0.7:H is determined by migration of the photo-excited carriers to non-radiative recombination centers. The physical mechanisms that can be involved in the strong enhancement of visible photoluminescence in Si:C:O:H layers are discussed. 相似文献
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Nine compounds, namely Li3BO3, -Li4B2O5, β-Li4B2O5, Li6B4O9, -LiBO2, Li2B4O7, Li3B7O12, LiB3O5 and Li2B8O13 in the Li2O–B2O3 system have been synthesized and characterized. The unit-cell parameters, density and solubility in water at room temperature of all the compounds are reported. The densities of the compounds were found to be in the 1.90–2.50 g cm−3 range, while their solubility in water at room temperature was in the 0.91–8.64×10−2 g cm−3 range. Determination of the thermal stability of the compounds by quenching and differential thermal analysis (DTA) showed that only -LiBO2 and Li2B4O7 retained their original symmetry up to their congruent melting at 1121 and 1188 K, respectively, in air. 相似文献
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Didier Astruc Amalia Rapakousiou Yanlan Wang Rodrigue Djeda Abdou Diallo Jaime Ruiz 《Journal of Coordination Chemistry》2014,67(23-24):3809-3821
Various types of mixed-valent metallodendrimers and star-shaped macromolecules containing ferrocenyl, biferrocenyl, or other redox-robust iron groups with rigid or flexible tethers of short and long lengths mostly studied in the authors’ laboratory including the class type in terms of Robin-Day classification and their functions including electrode modification, sensing, and nanoparticle templates are discussed in this mini review. 相似文献
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The structure of the trimolecular liquid mixture of 2:6:1 cyclohexene, tert-butyl alcohol, and water has been investigated using hydrogen/deuterium substitution neutron scattering techniques, and a three-dimensional structural model refined to be consistent with the experimental data has been built using the technique of Empirical Potential Structure Refinement. The model shows a well-mixed solution of the three molecular components where the competing interactions between the nonpolar cyclohexene and polar water molecules are balanced in the solution leading to largely pure-alcohol-like interactions between the tert-butyl alcohol molecules. Cyclohexene molecules favor direct solvation by alcohol methyl groups while water molecules are accommodated, dispersed throughout the solution, via hydrogen bonding interactions with the alcohol molecule hydroxyl groups. Rare occurrences of direct cyclohexene-water interactions are of the classic hydrophobic hydration type and no evidence is found for microscopic heterogeneity in the trimolecular mixture in contrast to the general findings for binary alcohol-water solutions. 相似文献
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980 nm脉冲激光激发下,首次通过高温固相法制备Yb(10%):Er(1%):Tm(1%):LiTaO3(摩尔分数)多晶粉并实现室温上转换白光.X射线粉末衍射测试结果表明,Yb:Er:Tm:LiTaO3中的掺杂离子并没有改变晶格结构,以取代的方式存在于钽酸锂晶格中.结合功率曲线测试结果和上转换机制研究发现,产生上转换蓝光的Tm3+离子1G4态的布居主要来自双光子同时吸收过程.而单光子上转换输出的红光,则由Tm3+和Er3+离子之间的交叉弛豫过程产生,即3F2/3(Tm3+)+4I15/2(Er3+)→3H6(Tm3+)+4I9/2(Er3+).上转换绿光来源于Yb/Er离子对的二次能量传递. 相似文献
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Serum, in which there is a pathological ratio between its percentage of water and total solids concentration is a relatively frequent occurrence in a clinical chemistry laboratory. These two factors bear an inverse relationship to each other because as the solids increase, the water decreases in fixed volumes of serum. These solid classes are comprised of proteins, lipids and crystalloids, the latter being the smaller dissolved molecules distinguished in part by their ability to go from vascular sites to the tissues as with posture changes unlike serum proteins which remain in their vascular environment during such positional changes. Of the three solids classes, only the proteins and lipids can cause significant alterations in the distribution ratios where the lipids, especially the triglycerides appear to be the major offenders among these classes of compounds. When proteins or triglycerides are markedly elevated, some sera are obviously different in appearance as elevated triglycerides result in hazy to milky sera whereas elevated proteins are a more insidious presence in that serum retains the same yellowish color and clarity much as is seen in the normal circumstances. Mathematical corrective information is available for both excessive protein and triglyceride concentrations but they appear to be infrequently used. Similarly, clearing mechanisms due to triglyceride excesses are available, but except for kits where somewhat helpful detergent action is incorporated, most disturbed results rejected by automated instrumentation may either be rejected through instrument calibration or reported incorrectly if for some reason they are not asterisked by the instrumentation. The purpose of the present report is to describe the difficulties in obtaining accurate determinations of analyte concentrations in which there are creations of pseudo-hypo-findings along with the corrective actions that can be taken including a novel clearing mechanism when excess triglycerides create a problem such as a spectrophotometric perturbation. The rationale for terms such as water dilution or electrolyte exclusion with excess protein concentrations and plasma dilution with excess triglyceride concentrations will be suggested. 相似文献
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Tri-n-octylphosphine sulfide (TOPS) has been investigated as the stationary phase in reversed-phase partition paper Chromatographie separations using nitric or hydrochloric acids as the mobile phase. TOPS has also been studied as an extractant for metal ions. Silver, mercury (II), and palladium (II) were found to have RF values of zero when nitric acid was used as the mobile phase. These same ions were also selectively extracted from aqueous nitric acid solutions. Gold(III), mercury(II), palladium (II), and platinum (IV) were found to have RF values of zero when hydrochloric acid was used as the mobile phase. However, only gold(III) and mercury(II) were extracted from aqueous hydrochloric acid solutions in liquid-liquid extraction systems. Several separations were successfully performed from 1 M nitric acid. 相似文献