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31.
Karl‐Christian Schwan Ariane Adolf Michael Bodensteiner Manfred Zabel Manfred Scheer 《无机化学与普通化学杂志》2008,634(8):1383-1387
The novel copper iodide clusters [Cu3(μ‐I)(μ3‐I)2(PH2BH2·NMe3)3] ( 2 ) and [Cu4(μ‐I)2(μ3‐I)2(PH2BH2·NMe3)3] ( 3 ) were synthesized by treating CuI with the primary phosphine (H2PBH2·NMe3). The novel features of both compounds, which have been characterized by X‐ray crystallography, are the unsymmetrical constitution of the copper iodide core due to the influence of the monodentate phosphorus ligand. This results in copper atoms with different coordination numbers within the compound. Complex 2 , the major product of the reaction, contains a distorted octahedral Cu3I3‐core, in which one vertex is missing. Complex 3 was isolated as a by‐product and is composed of a Cu4I4‐core in a distorted octahedral coordination. 相似文献
32.
Tobias Weissenberger Rainer Leonhardt Dr. Benjamin Apeleo Zubiri Dr. Martina Pitínová-Štekrová Dr. Thomas L. Sheppard Bastian Reiprich Dr. Jürgen Bauer Dr. Ralf Dotzel Maik Kahnt Dr. Andreas Schropp Prof. Christian G. Schroer Prof. Jan-Dierk Grunwaldt Dr. John L. Casci Prof. Jiří Čejka Prof. Erdmann Spiecker Prof. Wilhelm Schwieger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(63):14430-14440
The successful synthesis of hierarchically structured titanium silicalite-1 (TS-1) with large intracrystalline macropores by steam-assisted crystallisation of mesoporous silica particles is reported. The macropore topology was imaged in 3D by using electron tomography and synchrotron radiation-based ptychographic X-ray computed tomography, revealing interconnected macropores within the crystals accounting for about 30 % of the particle volume. The study of the macropore formation mechanism revealed that the mesoporous silica particles act as a sacrificial macropore template during the synthesis. Silicon-to-titanium ratio of the macroporous TS-1 samples was successfully tuned from 100 to 44. The hierarchically structured TS-1 exhibited high activity in the liquid phase epoxidation of 2-octene with hydrogen peroxide. The hierarchically structured TS-1 surpassed a conventional nano-sized TS-1 sample in terms of alkene conversion and showed comparable selectivity to the epoxide. The flexible synthesis route described here can be used to prepare hierarchical zeolites with improved mass transport properties for other selective oxidation reactions. 相似文献
33.
Sartori T Seigi Murakami F Pinheiro Cruz A Machado de Campos A 《Journal of chromatographic science》2008,46(6):505-509
A rapid and effective isocratic chromatographic procedure is successfully developed to determinate methotrexate (MTX) entrapment efficiency (EE) in polymeric nanocapsules using reversed-phase high-performance liquid chromatography. The method employed a RP-C(18) Shimadzu Shim-pack CLC-ODS (150 mm x 4.6 mm, 5 microm) column with mobile phase constituted by a mixture of water-acetonitrile-tetrahydrofuran (65:30:5 v/v/v; pH 3.0) at a flow rate of 0.8 mL/min. The eluate is monitored with a UV detector set at 313 nm. The parameters used in the validation process are: linearity, specificity, precision, accuracy, and limit of quantitation (LOQ). The linearity is evaluated by a calibration curve in the concentration range of 10-50 microg/mL and presented a correlation coefficient of 0.9998. The polymers (PLA or PLA-PEG), oil, and surfactants used in the nanocapsule formulation did not interfere with analysis and the recovery was quantitative. The intra and inter-day assay relative standard deviation were less than 0.72%. Results are satisfactory, and the method proved to be adequate for the determination of methotrexate in nanocapsules formulations. 相似文献
34.
Fastner S Predel R Kahnt J Schachtner J Wegener C 《Rapid communications in mass spectrometry : RCM》2007,21(1):23-28
The endocrine system of insects is largely based on peptide hormones. Nevertheless, an unequivocal chemical demonstration of the occurence in the hemolymph (the 'insect blood') is still lacking for most if not all insect peptide hormones, although this is the only way to prove their hormonal status. Focusing on peptides released during ecdysis behavior of the tobacco hornworm Manduca sexta, we developed a purification protocol based on ultrafiltration and a single reversed-phase high-performance liquid chromatography (RP-HPLC) step that for the first time allowed the mass spectrometric and chemical identification of a peptide hormone in the hemolymph of single specimens. Since this method is simple, relatively cheap and fast, it should be useful for routine endocrinological analyses and for monitoring peptide release during different physiological conditions and behaviors in insects. 相似文献
35.
In this paper we continue to develop the topological method to get semigroup generators of semi-simple Lie groups. Consider a subset \(\Gamma \subset G\) that contains a semi-simple subgroup \(G_{1}\) of G. If one can show that \( \Gamma \) does not leave invariant a contractible subset on any flag manifold of G, then \(\Gamma \) generates G if \(\mathrm {Ad}\left( \Gamma \right) \) generates a Zariski dense subgroup of the algebraic group \(\mathrm {Ad}\left( G\right) \). The proof is reduced to check that some specific closed orbits of \(G_{1}\) in the flag manifolds of G are not trivial in the sense of algebraic topology. Here, we consider three different cases of semi-simple Lie groups G and subgroups \(G_{1}\subset G\). 相似文献
36.
Slope and y-intercepts of locus equations have previously been shown to successfully classify place of articulation for English voiced stop consonants when derived from measurements at vowel onset and vowel midpoint. However, listeners are capable of identifying English voiced stops when less than 30 ms of vowel is presented. The present results show that modified locus equation measurements made within the first several pitch periods of a vowel following an English voiced stop were also successful at classifying place of articulation, consistent with the amount of vocalic information necessary for perceptual identification of English voiced stops /b d g/. 相似文献
37.
α- and β-thyrocalcitonic isolated from pig thyroids were found to be single-chain polypeptides with 32 amino acid residues containing a disulphide bridge. Tryptic digestion yielded inactive hepta-, undeca-and tetradecapeptides, the amino acid composition of which is given. β-thyrocalcitonin proved to be the methionine sulphoxide derivative of the easily oxidizable methionine peptide α-thyrocalcitonin; thus, the designation β can be eliminated. Both peptides have a potency of about 200 MRC units/mg dry weight. They can readily be differentiated by their electrophoretic and chromatographic properties, as well as by their tryptic undecapeptide, whereas the hepta- and tetradecapeptides, respectively, produced by trypsin are identical. 相似文献
38.
Valérie Marvaud Juan M. Herrera Thomas Barilero Fabien Tuyeras Raquel Garde Ariane Scuiller Caroline Decroix Martine Cantuel Cédric Desplanches 《Monatshefte für Chemie / Chemical Monthly》2003,169(1):149-163
This paper points out some recent achievements in the chemistry and physics of high spin and anisotropic molecules based on polycyanometalate complexes. Following a step by step synthetic strategy and using a localized electron orbital model, isotropic high spin molecules were obtained with ground spin states ranging from S = 9/2 to 27/2. In the same way, anisotropic molecules with various nuclearities (bi, tri, tetra, hexa, and hepta-nuclear complexes) have been synthesized. Mixing these two approaches, it has been possible to obtained anisotropic high spin molecules that behave as single molecule magnets. The paper reviews some of the steps that lead to these findings and some of the prospects opened in the field of single molecule magnets. 相似文献
39.
Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) is a soft ionization MS technique providing only minor fragmentation of the analyte. Therefore, the method is basically suitable for mixture analysis, although the ion yields strongly depend on the basicity/acidity of the analyte in relation to the applied matrix. Accordingly, less sensitively detectable compounds may be suppressed by more sensitively detectable compounds. Thus, separation of the mixture into the individual compounds is normally indispensable. This paper demonstrates the capabilities and limitations of a direct, simple, and inexpensive MALDI-high-performance thin-layer chromatography (HPTLC) coupling for the analysis of a crude lipid extract from porcine brain. Brain lipids were chosen because they represent a rather complex mixture and are of currently significant research interest. It was found that normal-phase HPTLC-separated lipids can be easily characterized by direct MALDI-TOF-MS analysis with sufficient resolution to allow the assignment of virtually all lipid classes, even rather minor species such as phosphorylated phosphoinositides or complex glycolipids as gangliosides. Advantages and disadvantages of this approach are discussed. 相似文献
40.