Quantitative analysis of closantel and rafoxanide in bovine and ovine muscles by high-performance liquid chromatography with fluorescence detection

An HPLC method with a fluorescence detector (HPLC-FLD) was described for the quantitative determination of closantel and rafoxanide in bovine and ovine muscles. A structural analog closely related to rafoxanide, viz., N-[4-(4-chlorophenoxy)phenyl]-2-hydroxy-3,5-diiodobenzamide, was synthesized as an internal standard. Bovine and ovine muscles were extracted with acetonitrile-acetone (60 + 40, v/v) followed by cleanup on mixed mode anionic exchange SPE cartridges. After evaporation and reconstitution with the mobile phase, the sample was analyzed by HPLC-FLD using internal standard calibration. The method was validated by using fortified bovine and ovine muscles at 15, 30, and 60 microg/kg. The accuracy and RSD were 70-110% and < or =10%, respectively.     

A facile chemical approach for preparing a SERS active silver substrate

This communication describes a new surface-enhanced Raman scattering (SERS) active silver substrate prepared by iodination of the evaporated silver foil. After iodination, the morphology of the silver substrate undergoes a self-evolution process in which it displays accordingly the UV-vis absorption shift as well as the AFM topological test. Rhodamine 6G (R6G) is used as the probe molecule to evaluate the enhancement efficiency of the silver substrate at different self-evolution time intervals. The SERS intensity of R6G increases up to ～29-fold and reaches a maximum after the substrate evolved for 24 h. This method is feasible for the production of an efficient SERS silver substrate.     

Comparison of different signal thresholds on data dependent sampling in orbitrap and LTQ mass spectrometry for the identification of peptides and proteins in complex mixtures

We evaluate the effect of ion-abundance threshold settings for data-dependent acquisition on a hybrid LTQ-Orbitrap mass spectrometer, analyzing features such as the total number of spectra collected, the signal to noise ratio of the full MS scans, the spectral quality of the tandem mass spectra acquired, and the number of peptides and proteins identified from a complex mixture. We find that increasing the threshold for data-dependent acquisition generally decreases the quantity but increases the quality of the spectra acquired. This is especially true when the threshold setting is set above the noise level of the full MS scan. We compare two distinct experimental configurations: one where full MS scans are acquired in the Orbitrap analyzer while tandem MS scans are acquired in the LTQ analyzer, and one where both full MS and tandem MS scans are acquired in the LTQ analyzer. We examine the number of spectra, peptides, and proteins identified under various threshold conditions, and we find that the optimal threshold setting is at or below the respective noise level of the instrument regardless of whether the full MS scan is performed in the Orbitrap or in the LTQ analyzer. When comparing the high-throughput identification performance of the two analyzers, we conclude that, used at optimal threshold levels, the LTQ and the Orbitrap identify similar numbers of peptides and proteins. The higher scan speed of the LTQ, which results in more spectra being collected, is roughly compensated by the higher mass accuracy of the Orbitrap, which results in improved database searching and peptide validation software performance.     

Structures and Properties of Nonchelated,d0 Alkyl Alkene Complexes of the Type [Cp2ZrMe(alkene)]+: Elusive Intermediates during Ziegler–Natta Polymerizations of Alkenes

Caught in the act : An alkyl alkene Zr^IV complex (see picture; Cp=C₅H₅) has been synthesized and characterized for the first time. The alkene bonding mode is highly asymmetric, and C2 is quite carbocationic. There is also evidence for rotation about the C1? C2 bond. This extremely unusual complex provides an exemplar of previously unknown intermediates in Ziegler–Natta and carbocationic polymerization reactions of alkenes.

     

Strong sums of projections in von Neumann factors

This paper presents necessary and sufficient conditions for a positive bounded operator on a separable Hilbert space to be the sum of a finite or infinite collection of projections (not necessarily mutually orthogonal), with the sum converging in the strong operator topology if the collection is infinite. A similar necessary condition is given when the operator and the projections are taken in a type II von Neumann factor, and the condition is proven to be also sufficient if the operator is “diagonalizable”. A simpler necessary and sufficient condition is given in the type III factor case.     

Optimal Estimator for Distributed Anonymous Observers

In this paper, we consider a distributed estimation problem in which multiple observations of a signal process are combined via the maximum function for the decision making. A key result established is that, under suitable technical conditions, the optimal decision function can be implemented by means of thresholds. A natural question is how to determine the optimal threshold value. We propose here an algorithm for threshold adjustment by means of training sequences. The algorithm is a variation of the Kiefer-Wolfowitz algorithm with expanding truncations and randomized differences. A result of the paper is to establish the convergence of the algorithm if the variance of observation noises is small enough.     

Operations management of new project development: innovation,efficient, effective aspects

The integration of distribution management systems (DMS) and feeder management systems (FMS) in China has become a trend in recent years, in addition to upgrading and rebuilding the existing energy management system and DMS. However, some management methods are different and contradictory, thus result in obstacles to innovation and effectiveness. Thus, firms still struggle to find effective process management that is associated with innovative project operations. In addition, there is no standard method to evaluate information technology (IT) projects, and at least 40% of IT projects realize no benefits. It is astonishing that none of the above-mentioned issues have been addressed or solved by previous literatures. In order to fill the vacancy, this paper first briefly introduces FMS and determines its critical success criteria, and then proposes suitable forms of organization for knowledge management. It also applies process management methods according to knowledge creation mode and maturity of the project. Finally, an analytic network process associated with benefits, opportunities, costs, and risks is constructed to compare the performance of different FMS projects with and without adopting the proposed methodology.     

A REACTIVE DYNAMIC CONTINUUM USER EQUILIBRIUM MODEL FOR BI-DIRECTIONAL PEDESTRIAN FLOWS

In this paper, a reactive dynamic user equilibrium model is extended to simulate two groups of pedestrians traveling on crossing paths in a continuous walking facility. Each group makes path choices to minimize the travel cost to its destination in a reactive manner based on instantaneous information. The model consists of a conservation law equation coupled with an Eikonal-type equation for each group. The velocity-density relationship of pedestrian movement is obtained via an experimental method. The model is solved using a finite volume method for the conservation law equation and a fast-marching method for the Eikonal-type equation on unstructured grids. The numerical results verify the rationality of the model and the validity of the numerical method. Based on this continuum model, a number of results, e.g., the formation of strips or moving clusters composed of pedestrians walking to the same destination, are also observed.     

ASYMPTOTICS OF ORTHOGONAL POLYNOMIALS VIA THE RIEMANN-HILBERT APPROACH

In this survey we give a brief introduction to orthogonal polynomials, including a short review of classical asymptotic methods. Then we turn to a discussion of the Riemann-Hilbert formulation of orthogonal polynomials, and the Delft ＆ Zhou method of steepest descent. We illustrate this new approach, and a modified version, with the Hermite polynomials. Other recent progress of this method is also mentioned, including applications to discrete orthogonal polynomials, orthogonal polynomials on curves, multiple orthogonal polynomials, and certain orthogonal polynomials with singular behavior.