When used in small molar ratios of matrix to analyte, derivatized fullerenes and single wall nanotubes are shown to be efficient matrices for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The mixing of an acidic functionalized fullerene with a solution of bioanalyte, depositing a dried droplet, and irradiating with a pulsed nitrogen laser yields protonated or cationized molecular ions. Derivatized fullerenes could offer several advantages over conventional MALDI matrices: a high analyte ionization efficiency, a small molar ratios (less than 1) of matrix/analyte, and a broader optical absorption spectrum, which should obviate specific wavelength lasers for MALDI acquisitions. The major disadvantage to the use of fullerenes is the isobaric interference between matrix and analyte ions; however, it is overcome by using MALDI-ion mobility time-of-flight (IM-oTOF) mass spectrometry to preseparate carbon cluster ions from bioanalyte ions prior to TOF mass analysis. However, an alternative to the dried droplet preparation of fullerene MALDI samples is the aerosolization of matrix-analyte solutions (or slurries) followed by impacting the aerosol onto a stainless surface. We also demonstrate that the fullerene matrices can be used to acquire spectra from rat brain tissue. 相似文献
Isotope ratios and elemental concentrations were measured in aqueous solutions sampled at varying distances from sources of Fe or Zn ions. The measurements reveal fractionation of isotopes resulting from pure diffusion in solution. Our data demonstrate that diffusion alone can cause changes in (56)Fe/(54)Fe and (66)Zn/(64)Zn isotope ratios in excess of -0.3 per thousand. These findings thus confirm previous suspicions that transport processes contribute to observed variations in isotopic compositions. Diffusion must therefore be considered when attempting to make inferences from isotope measurements on samples originating from aqueous systems where concentration gradients may develop. 相似文献
It is demonstrated that confocal epi-illumination/collection optics can be effectively used to generate surface-enhanced Raman scattering at the near-field region of a gold-coated tip for an atomic force microscope operated in semi-contact tapping mode. When the tip, with a 50-nm apex radius, was illuminated by a highly focused laser beam at 532 nm and approached the isolated diamond particle, with a size of approximately 1 microm, the Raman signal was enhanced by approximately 10(3). This result is in good agreement with numerical simulations performed by the finite difference time-domain method. Since our apertureless microscope is based on readily available conventional components, there is wide room for improvements and modifications by common users in various applications of micro-Raman analysis. 相似文献
In this article, the worst-case norm of the regulated output over all exogenous signals and initial states as a performance measure of the system is characterised in terms of linear matrix inequalities (LMIs). Optimal time-invariant state- and output-feedback controllers are synthesised as minimising this performance measure. The essential role in this synthesis plays a weighting matrix reflecting the relative importance of the uncertainty in the initial state contrary to the uncertainty in the exogenous signal. H∞-optimal control with transients is shown to be actually a trade-off between H∞-control, being optimal under unknown exogenous disturbances and zero initial state, and γ-control, being optimal under zero exogenous signal and unknown initial conditions, if and only if the weighting matrix satisfies a fundamental inequality. If this inequality is met, the performance measure is achieved and the explicit formulae for the worst-case disturbance and initial state are provided. If this inequality fails, the performance measure coincides with the H∞-norm and the trade-off gets broken. 相似文献
The first generation of DHT designs offered a completely flat structure of the key space that is randomly partitioned among
participating DHT nodes. That has certain advantages, for example, even distribution of workload among nodes. On the other
hand, grouping keys under a single authority or achieving latency guarantees for queries is difficult. To address these shortcomings,
various kinds of hierarchy have been proposed over recent years. The last generation is hierarchical DHTs (HDHTs) where nodes
are organized onto layers; each next layer consists of supernodes for the previous layer. In this survey paper, we thoroughly
go over the evolution of DHTs from pure flat to pre-hierarchical. Our focus is on hierarchical schemes in DHT routing. We
argue that their application is not restricted within HDHT designs. We sequentially built a set of design principles; each
provides a base for hierarchical routing schemes. In the extreme case, application these principles leads to HDHT designs. 相似文献
The novel μ3-oxo-bridged heterotrinuclear iron(III)-copper(II) trichloroacetates of the composition [Fe2CuO(CCl3COO)6(THF)3] (1a) and [Fe2CuO(CCl3COO)6(4-DMAP)3] (1b) have been synthesized and characterized by X-ray crystallography, IR and Mossbauer spectroscopy. These clusters were used as precursors for the synthesis of the nanosized catalytic system (~5–6 nm of γ-Fe2O3/CuO), which works as an efficient organic phase catalyst (~0.02 mol%) in a one-pot three component Biginelli synthesis. 相似文献
In this article, we propose methods that increase numerical efficiency of dynamic simulation of spatial multibody systems
described in absolute coordinates. The successive coordinate projection method efficiently stabilizes the system constraints
in the case when a non-minimal set of orientation coordinates is used to describe the orientation of bodies in space. The
new procedure of generation of Newton–Euler equations is shown in detail for systems with the most popular types of joints
(prismatic joint, revolute joint, etc.). The proposed algorithms were tested with models of a governor mechanism and Yamaha
YZF-R1 motorcycle engine. The simulation results show that the successive coordinate projection method is stable and can be
implemented for complex mechanical systems. 相似文献
An important commitment in the UN Framework Convention on Climate Change is to conduct mitigation analysis and to communicate climate change measures and polices. In major part reducing CO2 as well as the other greenhouse gas emissions in Kazakstan can be a side-product of measures addressed to increasing energy efficiency. Since such measures are very important for the national economy, mitigation strategies in the energy sector of Kazakstan are directly connected with the general national strategy of the energy sector development. This paper outlines the main measures and technologies in energy sector of Kazakstan which can lead to GHG emissions reduction and presents the results of current mitigation assessment.
The mitigation analysis addressed to energy production sector. A baseline and six mitigation scenarios were developed to evaluate the most attractive mitigation options, focusing on specific technologies which have been already included in sustainable energy programs. According to the baseline projection, Kazakstan's CO2 emissions will not exceed their 1990 level until 2005. The potential for CO2 emission reduction is estimated to be about 11% of the baseline emission level by the end of considered period (in 2020). The main mitigation options in the energy production sector in terms of mitigation potential and technical and economical feasibility include rehabilitation of thermal power plants aimed to increasing efficiency, use of nuclear energy, and further expansion in the use of hydro energy based on small hydroelectric power plants. 相似文献