排序方式: 共有50条查询结果,搜索用时 63 毫秒
1.
NIKITIN S.; PR?TZEL-WOLTERS D. 《IMA Journal of Mathematical Control and Information》1991,8(4):431-439
In 1983 Morse proved, for unknown scalar one-dimensional linearsystems, the nonexistence of rational or polynomial universalstabilizers (UAS). In 1983, Nussbaum gave an example of an analyticUAS. In our paper, it is shown that there exist time-invariantpolynomial UAS's with multidimensional gain adaptation. Thedesign procedure is developed for linear, minimum-phase systemsof relative degree one. Convergence of the closed-loop systemis proved. Some numerical simulations are provided. 相似文献
2.
Polfer NC Haselmann KF Zubarev RA Langridge-Smith PR 《Rapid communications in mass spectrometry : RCM》2002,16(10):936-943
Electron capture dissociation (ECD) of polypeptides has been demonstrated using a commercially available 3 Tesla Fourier transform ion cyclotron resonance (FTICR) instrument. A conventional rhenium filament, designed for high-energy electron impact ionisation, was used to effect ECD of substance P, bee venom melittin and bovine insulin, oxidised B chain. A retarding field analysis of the effective electron kinetic energy distribution entering the ICR cell suggests that one of the most important parameters governing ECD for this particular instrument is the need to employ low trapping plate voltages. This is shown to maximise the abundance of low-energy electrons. The demonstration of ECD at this relatively low magnetic field strength could offer the prospect of more routine ECD analysis for the wider research community, given the reduced cost of such magnets and (at least theoretically) the greater ease of electron/ion cloud overlap at lower field. 相似文献
3.
Dyson PJ Hearley AK Johnson BF Langridge-Smith PR McIndoe JS 《Inorganic chemistry》2004,43(16):4962-4973
A variety of homonuclear and heteronuclear transition metal carbonyl clusters have been analyzed by ultraviolet laser desorption/ionization time-of-flight mass spectrometry. The spectra were recorded in negative and positive ion modes, using both linear and reflective techniques. A range of different clusters based on different nuclearities, geometries, and ligand types, which include hydrides, phosphines, nitriles, and cyclopentadienyl ligands and naked main group atoms, were studied. These experiments have allowed us to construct a detailed picture of the technique for the analysis of transition metal carbonyl clusters and their derivatives. In general, extensive reactions are observed, cluster aggregation reactions in particular, and from a comparison of the spectra obtained, some mechanistic inferences concerning the aggregation processes have been drawn. 相似文献
4.
Blindauer CA Polfer NC Keiper SE Harrison MD Robinson NJ Langridge-Smith PR Sadler PJ 《Journal of the American Chemical Society》2003,125(11):3226-3227
Using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry, we show that one Zn2+ ion in the Zn4 cluster of cyanobacterial metallothionein is inert to exchange with 67Zn2+. We suggest that this is zinc in site A, which together with the surrounding alpha and beta secondary structure forms a zinc-finger fold. 相似文献
5.
An alternative approach to synthesize pedamide,a key building block of pederin was described.Iodine-induced asymmetric heterocyclization was used as the key step to construct the skeleton,a tetrahydropyran ring with three chiral centers.Brown's asymmetric allylation and Lewis acid-mediated allylation were investigated to introduce chains and chiral alcohols.Sharpless dihydroxylation decorated the side chain.And high optically pure target was obtained by removing the epimers formed in these reactions on c... 相似文献
6.
A convenient route for the synthesis of 3,4-dihydrocoumarin derivates from salicylaldehyde derivates and 1,3-dicarbonyl compounds under solvent-free microwave irradiation conditions was described. In this way, a range of compounds was obtained in moderate to good yields in a short reaction time. 相似文献
7.
Adam A. Stokes David J. Clarke Stefan Weidt Pat Langridge-Smith C. Logan Mackay 《International journal of mass spectrometry》2010,289(1):54-57
We report high resolution spectra for the medium molecular weight proteins myoglobin and cytochrome-c obtained using a custom desorption electrospray ionisation (DESI) source coupled to a Bruker Daltonics 12 T Apex Qe Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS). The DESI source was designed for accurate alignment and reproduction of critical geometric variables. A two axis motorised stage was included to enable automated rastering of the sample under the DESI plume. Spectra for the intact proteins have been obtained under single-acquisition conditions and a top-down analysis of cytochrome-c was performed using both collision induced dissociation (CID) and electron capture dissociation (ECD) of the isolated [M+15H]15+ charge state. The sequence coverage is comparable to that obtained using electrospray ionisation, demonstrating the utility of top-down protein analysis by DESI FTICR-MS. 相似文献
8.
Self-injection length in La0.7Ca0.3MnO3-YBa2Cu3O7-δ ferromagnet-superconductor multilayer thin films
We have carried out extensive studies on the self-injection problem in barrierless heterojunctions between La0.7Ca0.3MnO3 (LCMO) and YBa2Cu3O7-δ (YBCO) thin films. The heterojunctions were formed in situ by sequentially growing LCMO and YBCO films on 〈100〉 LaAlO3 (LAO) substrate using a pulsed laser deposition (PLD) system. YBCO micro-bridges with 64 μm width were patterned both on
the LAO (control) and LCMO side of the substrate. Critical current, I
c, was measured at 77 K on both the control side as well as the LCMO side for different YBCO film thickness. It was observed
that while the control side showed a J
c of ∼ 2 × 106 A/cm2, the LCMO side showed about half the value for the same thickness (1800 ?). The difference in J
c indicates that a certain thickness of YBCO has become ‘effectively’ normal due to self-injection. From the measurement of
J
c at two different thicknesses (1800 ? and 1500 ?) of YBCO films both on the LAO as well as the LCMO side, the value of self-injection
length (at 77 K) was estimated to be ∼ 900 ?. To the authors’ best knowledge, this is the first time that self-injection length
has been quantified. A control experiment carried out with LaNiO3 deposited by PLD on YBCO did not show any evidence of self-injection. 相似文献
9.
Clarke DJ Murray E Hupp T Mackay CL Langridge-Smith PR 《Journal of the American Society for Mass Spectrometry》2011,22(8):1432-1440
Noncovalent protein–ligand and protein–protein complexes are readily detected using electrospray ionization mass spectrometry
(ESI MS). Furthermore, recent reports have demonstrated that careful use of electron capture dissociation (ECD) fragmentation
allows covalent backbone bonds of protein complexes to be dissociated without disruption of noncovalent protein–ligand interactions.
In this way the site of protein–ligand interfaces can be identified. To date, protein–ligand complexes, which have proven
tractable to this technique, have been mediated by ionic electrostatic interactions, i.e., ion pair interactions or salt bridging.
Here we extend this methodology by applying ECD to study a protein–peptide complex that contains no electrostatics interactions.
We analyzed the complex between the 21 kDa p53-inhibitor protein anterior gradient-2 and its hexapeptide binding ligand (PTTIYY).
ECD fragmentation of the 1:1 complex occurs with retention of protein–peptide binding and analysis of the resulting fragments
allows the binding interface to be localized to a C-terminal region between residues 109 and 175. These finding are supported
by a solution-phase competition assay, which implicates the region between residues 108 and 122 within AGR2 as the PTTIYY
binding interface. Our study expands previous findings by demonstrating that top-down ECD mass spectrometry can be used to
determine directly the sites of peptide–protein interfaces. This highlights the growing potential of using ECD and related
top-down fragmentation techniques for interrogation of protein–protein interfaces. 相似文献
10.