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Mass spectrometry based proteomics,background,status and future needs

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Protein & Cell 2012年第9期3卷 641-647页

作者： peter Roepstorff Department of Biochemistry and Molecular Biology University of Southern Denmark Campusvej 55DK 5230 Odense MDenmark

An overview of the background for proteomics and a description of the present state of art are given with a description of the main strategies in *** advantages and limitations of the two major strategies,2D-gel based and LC-MS based,are discussed and a combination for the two,CeLC-MS is described.A number of challenging problems which have been solved using different proteomics strategies including the advantage of organell enrichment or modifications specific peptide isolation to get deeper into the proteome are *** the present status and future needs discussed.

关键词： proteomics 2D-PAGE LC-MS isoforms phosphorylation

Non-Achievability of Metal-Insulator Transition in Two-Dimensional Systems

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Chinese Physics Letters 2006年第4期23卷 946-949页

作者： A. John peter Zhejiang Institute of Modern Physics Zhejiang University Hangzhou 310027

We present a simple demonstration of the nonfeasibility of metal-insulator transition in an exactly two-dimensional （2D） system. The Hartree-Fock potential in the 3D system is suitably modified and presented for the 2D case. The many body effects are included in the screening function, and binding energies of a donor are obtained as a function of impurity concentration so as to find out the possible way leading metal-insulator transition in the 2D system. While solving for the binding energy for a shallow donor in an isolated well of a GaAs/Ga1-x Als As superlattice system within the effective mass approximation, it leads to unphysical results for higher concentrations. It shows that the phase transition, the bound electron entering into the conduction band whereby （H）min=0, is not possible beyond this concentration. The results suggest thai a phase transition is impossible in 213 systems, supporting the scaling theory of localization. The results are compared with the existing data available and discussed in the light of existing literature.

关键词： MOTT TRANSITION QUANTUM-WELLS ELECTRON-GAS 2 DIMENSIONS LOCALIZATION

Limits on light emission from silicon

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Chinese Optics Letters 2009年第4期7卷 268-270页

作者： peter Würfel Institut für Angewandte Physik Universitt KarlsruheD-76128 KarlsruheGermany

Although silicon is an indirect semiconductor, light emission from silicon is governed by the same gener- alized Planck＇s radiation law as the emission from direct semiconductors. The emission intensity is given by the absorptance of the volume in which there is a difference of the quasi Fermi energies. A difference of the Fermi energies may result h＇om the absorption of external light （photoluminescence） or from the injection of electrons and holes via selective contacts （electroluminescence）. The quantum efficiency may be larger than 0.5 for carrier densities below 10^15 cm^-3. At larger densities, non-radiative recombination, in particular Auger recombination dominates. At all carrier densities, the relation between emission intensity and difference of the quasi Fermi energies is maintained. Since this difference is equal to the voltage of a properly designed solar cell, luminescence is the key indicator of material quality for solar cells.

关键词： Carrier concentration Fermi level Light Light emission Photoluminescence Semiconducting silicon Silicon

THE USE OF PLANE WAVES TO APPROXIMATE WAVE PROPAGATION IN ANISOTROPIC MEDIA

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Journal of Computational Mathematics 2007年第3期25卷 350-367页

作者： Tomi Huttunen peter Monk Department of Physics University of KuopioP.O.Box 1627FIN-70211 KuopioFinland Department of Mathematical Sciences University of DelawareNewarkDE 19716USA

In this paper we extend the standard Ultra Weak Variational Formulation （UWVF） of Maxwell＇s equations in an isotropic medium to the case of an anisotropic medium. We verify that the underlying theoretical framework carries over to anisotropic media （however error estimates are not yet available） and completely describe the new scheme. We then consider TM mode scattering, show how this results in a Helmholtz equation in two dimensions with an anisotropic coefficient and demonstrate how to formulate the UWVF for it. In one special case, convergence can be proved. We then show some numerical results that suggest that the UWVF can successfully simulate wave propagation in anisotropic media.

关键词： Ultra weak Maxwell Plane wave Anisotropic medium.

FUNCTIONAL POLYHYDROXYALKANOATES SYNTHESIZED BY MICROORGANISMS

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Chinese Journal of Polymer Science 2000年第5期18卷 389-396页

作者： peter H.Yu Open Laboratory of Chiral Technology Hong Kong Polytechnic University Hong Kong China

Many bacteria have been found to synthesize a family of polyesters termed polyhydroxyalkanoate, abbreviated as PHA. Some interesting physical properties of PHAs such as piezoelectricity, non-linear optical activity, biocompatibility and biodegradability offer promising applications in areas such as degradable packaging, tissue engineering and drug delivery. Over 90 PHAs with various structure variations have been reported and the number is still increasing. The mechanical property of PHAs changes from brittle to flexible to elastic, depending on the side-chainlength of PHA. Many attempts have been made to produce PHAs as biodegradable plastics using various microorganisms obtained from screening natural environments, genetic engineering and mutation. Due to the high production cost, PHAs still can not compete with the nondegradable plastics, such as polyethylene and polypropylene. Various processes have been developed using low cost raw materials for fermentation and an inorganic extraction process for PHA purification. However, a super PHA production strain may play the most critical role for any large-scale PHA production. Our recent study showed that PHA synthesis is a common phenomenon among bacteria inhabiting various locations, especially oil-contaminated soils. This is very important for finding a suitable bacterial strain for PHA production. In fact, PHA production strains capable of rapid growth and rapid PHA synthesis on cheap molasses substrate have been found on molasses contaminated soils. A combination of novel properties and lower cost will allow easier commercialization of PHA for many applications.

关键词： polyhydroxybutyrate polyhydroxyalkanoate biopolymer polyester

Adaptive nonlinear model predictive control design of a flexible-link manipulator with uncertain parameters

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Acta Mechanica Sinica 2017年第3期33卷 529-542页

作者： Fabian Schnelle peter Eberhard Institute of Engineering and Computational Mechanics University of Stuttgart

This paper presents a novel adaptive nonlinear model predictive control design for trajectory tracking of flexible-link manipulators consisting of feedback linearization, linear model predictive control, and unscented Kalman filtering. Reducing the nonlinear system to a linear system by feedback linearization simplifies the optimization problem of the model predictive controller significantly, which, however, is no longer linear in the presence of parameter uncertainties and can potentially lead to an undesired dynamical behaviour. An unscented Kalman filter is used to approximate the dynamics of the prediction model by an online parameter estimation, which leads to an adaptation of the optimization problem in each time step and thus to a better prediction and an improved input action. Finally, a detailed fuzzy-arithmetic analysis is performed in order to quantify the effect of the uncertainties on the control structure and to derive robustness assessments. The control structure is applied to a serial manipulator with two flexible links containing uncertain model parameters and acting in three-dimensional space.

关键词： Model predictive control Feedback linearization Unscented Kalman filter Flexible-link manipulator Fuzzy-arithmetical analysis

Spatially-Structured Sharing Technique for Multimodal Problems

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Journal of Computer Science & Technology 2008年第1期23卷 64-76页

作者： Grant Dick peter Whigham Department of Information Science University of OtagoDunedin

Spatially-structured populations are one approach to increasing genetic diversity in an evolutionary algorithm （EA）. However, they are susceptible to convergence to a single peak in a multimodal fitness landscape. Niching methods, such as fitness sharing, allow an EA to maintain multiple solutions in a single population, however they have rarely been used in conjunction with spatially-structured populations. This paper introduces local sharing, a method that applies sharing to the overlapping demes of a spatially-structured population. The combination of these two methods succeeds in maintaining multiple solutions in problems that have previously proved difficult for sharing alone （and vice-versa）.

关键词： evolutionary algorithm multimodal problem domain sharing spatially-structured population

Influence of entrainer recycle for batch heteroazeotropic distillation

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Frontiers of Chemical Science and Engineering 2018年第4期12卷 643-659页

作者： Laszlo Hegely peter Lang Department of Building Service and Process Engineering Faculty of Mechanical Engineering Budapest University of Technology and EconomicsMuegyetem rkp.3-9Hungary

Dehydration of isopropanol applying batch heteroazeotropic distillation with toluene as entrainer (E) is investigated. The composition of the feed is near to that of the isopropanol (A)-water (B) azeotrope. The effects of recycling the entrainer and the off-cut are studied by dynamic simulation with a professional flow-sheet simulator. Three consecutive batches (one production cycle) is studied. Both operational modes (Mode I: decantation after distillation and Mode II: decantation during distillation) are simulated. For Mode II, calculations are performed both for Strategy A (distillate from the aqueous (E-lean) phase only) and Strategy B (partial withdrawal of the organic (Erich phase), as well). The E-rich phase, the final column hold-up and the off-cut (Mode II only) are recycled to the next batch. The influence of the following parameters are determined: quantity of entrainer, reflux ratios of the steps. The variations caused by the recycling in the 2(nd) and 3(rd) batches are also shown. The best results (lowest specific energy demand and highest recovery of A) are obtained by Mode II, Strategy A. Recycling increases the recovery, and drastically diminishes the entrainer consumption. However, it makes the production slower and decreases the quantity of fresh feed that can be processed.

关键词： batch distillation heteroazeotropic distillation operational policies off-cut recycle entrainer

PRECONDITIONING BLOCK LANCZOS ALGORITHM FOR SOLVING SYMMETRIC EIGENVALUE PROBLEMS

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Journal of Computational Mathematics 2000年第4期18卷 365-374页

作者： Hua Dai peter Lancaster Nanjing University of Aeronautics and Astronautics Naming210018China University of Calgary CalgaryCanada

A preconditioned iterative method for computing a few eigenpairs of large sparse symmetric matrices is presented in this paper. The proposed method which combines the preconditioning techniques with the efficiency of block Lanczos algorithm is suitable for determination of the extreme eigenvalues as well as their multiplicities. The global convergence and the asymptotically quadratic convergence of the new method are also demonstrated. [ABSTRACT FROM AUTHOR]

关键词： eigenvalue eigenvector sparse matrices Lanczos method preconditioning