Multivariate comparison between peptide mass fingerprints obtained by liquid chromatography-electrospray ionization-mass spectrometry with different trypsin digestion procedures

Peptide mass fingerprints were obtained for three different proteins using three different digestion procedures in triplicates with liquid chromatography coupled to electrospray ionization mass spectrometry. For each protein the results were compared with multivariate data analysis (cluster analysis, kernel principal component analysis) and pair-wise contrast evaluation. Clear systematic differences between the digestion procedures were established for all the proteins. The visual presentation of the pair-wise differences between procedures could to some extent be related to the protein fragments, although the main objective was to identify m/z and retention regions in the original peptide maps that should be subject to further exploration.     

Iron and Cobalt Complexes of a Series of Tridentate P,N, P Ligands — Synthesis,Characterization, and Application in Ethene Polymerization Reactions

A series of tridentate P, N, P ligands comprising a central pyridine unit and two pendent diarylphosphane moieties (2, 6‐bis(CH₂PAr₂)pyridine; Ar = phenyl ( 1 ), 2‐methylphenyl ( 2 ), 2, 4, 6‐trimethylphenyl ( 3 )) as well as the corresponding iron ( 1‐FeCl₂ , 2‐FeCl₂ , 3‐FeCl₂ ) and cobalt ( 1‐CoCl₂ , 2‐CoCl₂ , 3‐CoCl₂ ) complexes were synthesized and characterized. An X‐ray structure analysis of 2‐CoCl₂ and 3‐CoCl₂ exhibited a trigonal‐bipyramidal coordination geometry at the metal center, the two chlorine atoms and the nitrogen occupying the equatorial and the phosphane units the apical positions. IR analysis indicated, that in all complexes the pyridine unit is coordinated to the metal center. The cobalt compounds were applied as catalyst precursors for the polymerization of ethene after activation with MAO.     

Poly­[[tetra­aqua(μ7‐hydrogen di­chloro­methyl­enebis­phospho­nato)(μ5‐hydro­gen di­chloro­methyl­enebis­phosphon­ato)­tribarium(II)] monohydrate]

The title compound, {[Ba₃(CHCl₂O₆P₂)₂(H₂O)₄]·H₂O}_n or {[Ba₃(Cl₂CP₂O₆H)(H₂O)₄]·H₂O}_n, is two‐dimensional. The asymmetric unit contains three independent Ba²⁺ atoms, two chelating and bridging Cl₂CP₂O₆H³⁻ ligands and four aqua ligands, connected in layers parallel to the (100) plane. There are pores between the layers in the direction of the b axis filled with lattice water mol­ecules.     

Comparison between the classical theory predictions and molecular simulation results for heterogeneous nucleation of argon

We have performed Monte Carlo simulations of homogeneous and heterogeneous nucleations of Lennard-Jones argon clusters. The simulation results were interpreted using the major concept posing a difference between the homogeneous and heterogeneous classical nucleation theories-the contact parameter. Our results show that the multiplication concept of the classical heterogeneous nucleation theory describes the cluster-substrate interaction surprisingly well even for small molecular clusters. However, in the case of argon nucleating on a rigid monolayer of fcc(111) substrate at T=60 K, the argon-substrate atom interaction being approximately one-third as strong as the argon-argon interaction, the use of the classical theory concept results in an underestimation of the heterogeneous nucleation rate by two to three orders of magnitude even for large clusters. The main contribution to this discrepancy is induced by the failure of the classical theory of homogeneous nucleation to predict the energy involved in bringing one molecule from the vapor to the cluster for clusters containing less than approximately 15 molecules.     

ESI-MS detection of proposed reaction intermediates in the air-promoted and ligand-modulated oxidative Heck reaction

Electrospray ionization mass spectrometry (ESI-MS) and subsequent MS/MS analyses were used to directly detect palladium-containing cationic reaction intermediates in a ligand controlled palladium(II)-catalyzed oxidative Heck arylation. All potential intermediates were observed as dmphen-ligated palladium(II) species, suggesting that the dmphen bidentate ligand is attached to the metal center during the entire catalytic cycle. The study supports previous mechanistic propositions and provides new information regarding the composition of aryl-containing Pd(II) complexes in an ongoing oxidative Heck reaction. In addition, sodium acetate was found to be a useful base alternative to previously used tertiary amines.     

System- and circuit-level optimization of PLL designs for DVB-T/H receivers

This article proposes a framework for the optimization of voltage-controlled oscillator (VCO) designs in frequency synthesizers for digital video broadcasting ?C terrestrial/handheld (DVB-T/H) receivers. Linear time-invariant phase-domain model of a charge-pump phase-locked loop (PLL) is devised and includes both flicker (1/f) and thermal noise contributions from the loop oscillators. By modeling the entire receiver, it is shown that there are combinations of flicker and thermal noise contributions that result in a constant sum of inter-carrier interference (ICI) and adjacent channel interference, and constant symbol error rate as well. Consequently, optimization of the VCO phase noise spectrum is defined while maintaining the standard-specified symbol-error rate. Link-level performance evaluation is carried out to validate the stipulated trade-off. The effect of ICI mitigation schemes is discussed. Circuit-level VCO design approaches utilizing the derived trade-off are finally presented. The proposed optimization procedure is generic and is also applicable to other systems based on Orthogonal Frequency-Division Multiplexing.     

Analysis of EMG and acceleration signals for quantifying the effects of deep brain stimulation in Parkinson's disease

Deep brain stimulation (DBS) is effective in reducing motor symptoms in Parkinson's disease (PD). However, objective methods for quantifying its efficacy are lacking. We present a principal component (PC)-based tracking method for quantifying the effects of DBS in PD by using electromyography (EMG) and acceleration measurements. Ten parameters capturing PD characteristic signal features were initially extracted from isometric EMG and acceleration recordings. Using a PC approach, the original parameters were transformed into a smaller number of PCs. Finally, the effects of DBS were quantified by examining the PCs in a low-dimensional feature space. The EMG and acceleration data from 13 PD patients with DBS ON and OFF, and 13 healthy age-matched controls were used for analysis. Clinical evaluation of patients showed that their motor symptoms were effectively reduced with DBS. The analysis results showed that the signal characteristics of 12 patients were more similar to those of the healthy controls with DBS ON than with DBS OFF. These observations indicate that the PC-based tracking method can be used to objectively quantify the effects of DBS on the neuromuscular function of PD patients. Further studies are suggested to estimate the clinical sensitivity of the method to different types of PD.     

Coherence-polarization mixing in resonance gratings

We show, using rigorous diffraction theory, that resonance gratings can be used to transfer partial spatial correlation to partial polarization even if the incident light beam is fully polarized. The phenomenon is based on the fact that either of the two orthogonal polarization components can be coupled into the leaky waveguide mode, leading to a strong phase delay, while the other one is reflected without being coupled into the grating. Numerical demonstrations are based on a Gaussian Schell-model beam and a grating analysis performed by rigorous Fourier modal method.     

Real options valuation of forest plantation investments in Brazil

In this paper, we consider investments in eucalyptus plantations in Brazil. For such projects, we discuss real options valuation in the place conventional methods such as IRR or NPV, possibly with CAPM. Traditionally, real options valuation assumes complete markets and neglects market imperfections. Yet, market frictions, such as transaction costs, interest rate spreads, and restricted short positions, can play an important role. We extend real options valuation to allow incomplete and imperfect markets. The value is obtained as a competitive price, given markets of competing investment opportunities, such as real and financial assets. Under perfect and complete markets, such valuation method is consistent with conventional real options theory. Stochastic programming and standard software is used for valuation of eucalyptus plantations. We estimate the underlying interdependent diffusion processes of stock market, interest rates, exchange rates and pulpwood price, and derive novel expressions of stochastic integrals to be employed in scenario generation for discrete time stochastic programming.     

Low Power High-Speed Neuron MOS Digital-to-Analog Converters with Minimal Silicon Area

Digital-to-analog converts utilizing neuron MOS-transistors were designed. Different DACs were implemented and characterized in order to compare various topologies. Criteria to select structures were low power, fast performance and minimal silicon area. A basic 8-bit version is implemented with only one neuron MOS-transistor and eight capacitors. The silicon area of this D/A converter is only 0.04 mm² and the power consumption is 8.4 mW with conversion speed of 200 MS/s. An enhanced 8 and 10 bit versions utilizing neuron PMOS transistor and some extra circuitry are also proposed and tested. The silicon area of the enhanced 10 bit circuit is only 0.03mm² while the performance is as good as in the case of the basic version. The measured differential nonlinearity is 0.38 LSB and integral nonlinearity is 0.55 LSB for the enhanced 10 bit structure.