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1.
Summary N-Benzoylphenylhydroxylarnine complexes of some metals have been investigated by HPLC. The green chromium complex formed by this reagent shows conclusive evidence of the presence of geometrical isomers. It is photosensitive and changes to a brown modification when irradiated with ultra violet or visible light. Elution behaviour of the complexes has been studied with different solvent mixtures. Attempts have been made to characterize the complexes from different measurements.
Untersuchung von isomeren Chrom-N-benzoylphenylhydroxylaminaten durch HPLC相似文献
2.
Sablinskas V Hegelund F Ceponkus J Bariseviciute R Aleksa V Nelander B 《The journal of physical chemistry. A》2005,109(39):8719-8723
Ozonization reaction of ethene in neat film at 77 K was performed. Separation of ethene secondary ozonide from the other products of the reaction was performed by continuous pumping of the reactor. Only the products, which evaporated from the walls of the reactor at 185 K, were transferred to the gas cell. The high-resolution infrared absorption spectrum of gaseous ethene secondary ozonide (C(2)H(4)O(3)) in a static gas long-path absorption cell has been recorded in the 900-1100 cm(-1) spectral region at 185 K. The spectral resolution was 0.003 cm(-1). Analyses of the nu(7)(A) band at 1037.0 cm(-1), the nu(8)(A) band at 956.1 cm(-1), and the nu(18)(B) band at 1082.1 cm(-1) have been performed using the Watson Hamiltonian model (A, reduction; III(r), representation). A set of ground-state rotational and quartic centrifugal distortion constants have been obtained, and upper state spectroscopic constants have been determined for the bands investigated. A local resonance observed in nu(18) is explained as c-Coriolis interaction with nu(10) + nu(11). 相似文献
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Desjardins A Flemming J Sternberg ED Dolphin D 《Chemical communications (Cambridge, England)》2002,(22):2622-2623
Protoporphyrin reacts with diazomethane to give pyrazolines which at long wavelength (approximately 630 nm) extrude nitrogen to give the corresponding cyclopropyl derivatives. 相似文献
6.
Lindorff-Larsen K Kristjansdottir S Teilum K Fieber W Dobson CM Poulsen FM Vendruscolo M 《Journal of the American Chemical Society》2004,126(10):3291-3299
The denatured state of a protein contains important information about the determinants of the folding process. By combining site-directed spin-labeling NMR experiments and restrained computer simulations, we have determined ensembles of conformations that represent the denatured state of the bovine acyl-coenzyme A binding protein (ACBP) at three different concentrations of guanidine hydrochloride. As the experimentally determined distance information corresponds to weighted averages over a broad ensemble of structures, we applied the experimental restraints to a system of noninteracting replicas of the protein by using a Monte Carlo sampling scheme. This procedure permits us to sample ensembles of conformations that are compatible with the experimental data and thus to obtain information regarding the distribution of structures in the denatured state. Our results show that the denatured state of ACBP is highly heterogeneous. The high sensitivity of the computational method that we present, however, enabled us to identify long-range interactions between two regions, located near the N- and C-termini, that include both native and non-native elements. The preferential formation of these contacts suggests that the sequence-dependent patterns of helical propensity and hydrophobicity are important determinants of the structure in the denatured state of ACBP. 相似文献
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Qiang Li Dr. Lei Liu Shuai Zhang Meng Xu Xueqin Wang Prof. Chen Wang Prof. Flemming Besenbacher Prof. Mingdong Dong 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(24):7236-7240
Graphene oxide (GO) is utilized as the modulator to tune the formation and development of amyloid fibrils (Aβ33–42). Atomic force microscopy temporal evolution measurements reveal that the initial binding between the peptide monomer and the large available surface of the GO sheets can redirect the assembly pathway of amyloid beta. The results support the possibility to develop graphene‐based materials to inhibit amyloidosis. 相似文献
9.
Jacobsen AM Halling-Sørensen B Ingerslev F Hansen SH 《Journal of chromatography. A》2004,1038(1-2):157-170
The veterinary antibacterial agents chlortetracycline (CTC), oxytetracycline (OTC), sulfadiazine (SDZ), erythromycin (ERY) and tylosin (TYL A, B, C and D) were extracted from soil using pressurized liquid extraction (PLE). Citric acid (pH 4.7) and methanol was used as extraction buffer, followed by tandem-solid-phase extraction (SPE) clean-up (SAX + HLB) for all compounds. For quantification two slightly different methods were employed using LC-MS-MS with MRM detection. The soil extraction method was validated using a loamy sand soil and a sandy soil, representing two typical Danish agricultural soils. Recoveries were 50-80% for the tetracyclines (CTC and OTC) and sulfadiazine (SDZ) and 60-100% for the macrolides (TYL and ERY). Limits of detection for the soil extraction method (LOD(soil)) were 0.6-5.6 microg kg(-1) soil for CTC and OTC, 0.9-2.9 microg kg(-1) soil for SDZ and 2.4-5.5 microg kg(-1) soil for TYL A and ERY. Furthermore, the method was applied to field samples taken from two agricultural fields fertilised with liquid manure containing CTC and TYL A. These results showed a decline in the content of antibacterial agents throughout the sampling period of 155 days from 10 to 15 microg CTC kg(-1) soil and 20-55 microg TYL A kg(-1) soil to below or near the LOD(soil) listed above. Finally, the method was applied to barley grains harvested from the fields. None of the antibacterial agents were measured in grain samples, but recoveries for spiked grain samples were similar to soil recoveries. 相似文献
10.
Estephania Lira Jonas ?. Hansen Peipei Huo Ralf Bechstein Patrick Galliker Erik L?gsgaard Bj?rk Hammer Stefan Wendt Flemming Besenbacher 《Surface science》2010,604(21-22):1945-1960
High-resolution scanning tunneling microscopy (STM) and temperature-programmed desorption (TPD) were used to study the interaction of O2 with reduced TiO2(110)–(1 × 1) crystals. STM is the technique of choice to unravel the relation between vacancy and non-vacancy assisted O2 dissociation channels as a function of temperature. It is revealed that the vacancy-assisted, first O2 dissociation channel is preferred at low temperature (~ 120 K), whereas the non-vacancy assisted, second O2 dissociation channel operates at temperatures higher than 150 K–180 K. Based on the STM results on the two dissociative O2 interaction channels and the TPD data, a new comprehensive model of the O2 chemisorption on reduced TiO2(110) is proposed. The model explains the relations between the two dissociative and the molecular O2 interaction channels. The experimental data are interpreted by considering the available charge in the near-surface region of reduced TiO2(110) crystals, the kinetics of the two O2 dissociation channels as well as the kinetics of the diffusion and reaction of Ti interstitials. 相似文献