Screening and identification of organophosphorus compounds related to the chemical weapons convention with 1D and 2D NMR spectroscopy

Two-dimensional 1H-31P Fast-HMQC was tested for determination of the presence in low concentrations of organophosphorus compounds related to the Chemical Weapons Convention. This method, based on inverse detection, demonstrated high sensitivity and selectivity. Background signals, such as solvent peaks, are suppressed with good efficiency, and organophosphorus compounds present at a concentration level 1-10 microg/mL can be detected within a few hours. In addition, phosphorus-selective one-dimensional 1H-31P HSQC-TOCSY was applied to produce a complete proton spectrum of selected organophosphorus compound from a sample containing intense background resonances. Application of the methods presented in this paper resulted in considerably improved performance of NMR spectroscopy as a complementary technique for screening as well as identification of chemical warfare agents in environmental samples.     

Novel mutant human fibronectin FIII9-10 domain pair with increased conformational stability and biological activity

The ninth and tenth type III domains (FIII9–10) in thecentral cell binding domain of human fibronectin contain integrinreceptor binding sites, including RGD in FIII10 and a synergysite, PHSRN, in FIII9. The specific amino acids that contributeto cell binding have been identified by the use of wild-typeand mutant fragments of human fibronectin containing the FIII9–10domain pair. At high concentrations FIII9–10 mimics, toa large extent, the biological activity of the full-length fibronectinmolecule. However, FIII9 is conformationally unstable, evenin the context of the FIII9–10 pair. Here we report theconstruction of a series of hybrid mouse–human FIII9–10pairs that confer varying degrees of conformational stabilityto FIII9. The conformational stability of the human FIII9 modulewas increased 2–3-fold by substitution of Leu1408 withPro. We demonstrate that the biological activity of this mutantis enhanced. The resulting FIII9–10 mutant has good solutionproperties and will provide a template into which further mutationscan be incorporated in order to probe the structure–functionrelationship of the cell binding module of fibronectin.     

A DDS Synthesizer with Digital Time Domain Interpolator

A DDS type circuit structure for producing numericallyprogrammable square wave clock signal is presented. The high speed D/Aconverter needed in conventional DDS systems is replaced by an tap delay line time domain interpolator thateffectively increases the sampling rate by a factor of . Thus the circuit can be used up to full clock rate withoutimage filtering. A prototype IC with clock frequency of 30 MHz, 5 bitinterpolator and SFDR of –40 dBc up to 10 MHz and –33 dBcup to 15 MHz has been designed and tested.     

Effects of stimulation parameters on behavior elicited by stimulation of the hypothalamic defense area.

Elicited agonistic behavior by stimulating the ventromedial hypothalamus of 22 domestic cats. 12 different behavioral components were rated separately. Behavioral alerting, mydriasis, retraction of ears, piloerection, hissing, and protrusion of claws were the most characteristic components. The parameters of the stimulus were shown to be important determinants of the nature of the behavior. Results suggest that either discrete central neural circuits for the different components of agonistic behavior are diffusively organized within the ventromedial hypothalamus, or the components result from a general activation of neurons subserving discrete fixed-action patterns, the resultant behavior being determined by different factors, such as the intensity of the activation. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automatic detection of harvested trees and determination of forest growth using airborne laser scanning

This paper demonstrates the applicability of small footprint, high sampling density airborne laser scanners for boreal forest change detection, i.e. the estimation of forest growth and monitoring of harvested trees. Two laser acquisitions were carried out on a test site using a Toposys-1 laser scanner. Three-dimensional canopy height models were calculated for both data sets using raster-based algorithms. Object-oriented algorithms were developed for detecting harvested and fallen trees, and for measuring forest growth at plot and stand levels. Out of 83 field-checked harvested trees, 61 could be automatically and correctly detected. All mature harvested trees were detected; it was mainly the smaller trees that were not. Forest growth was demonstrated at plot and stand levels using an object-oriented tree-to-tree matching algorithm and statistical analysis. The precision of the estimated growth, based on field checking or statistical analysis, was about 5 cm at stand level and about 10–15 cm at plot level. The authors expect that the methods may be feasible in large area forest inventories that make use of permanent sample plots. Together with methods for detecting individual sample trees, the methods described may be used to replace a large number of permanent plots with laser scanning techniques.     

Interacting with parallel coordinates

Parallel coordinate visualizations have a reputation of being difficult to understand, expert-only representations. We argue that this reputation may be partially unfounded, because many of the parallel coordinate browser implementations lack essential features. This paper presents a survey of current interaction techniques for parallel coordinate browsers and compares them to the visualization design guidelines in the literature. In addition, we report our experiences with parallel coordinate browser prototypes, and describe an experiment where we studied the immediate usability of parallel coordinate visualizations. In the experiment, 16 database professionals performed a set of tasks both with the SQL query language and a parallel coordinate browser. The results show that although the subjects had doubts about the general usefulness of the parallel coordinate technique, they could perform the tasks more efficiently with a parallel coordinate browser than with their familiar query language interface.     

Temperature-induced inversion of the elution order of enantiomers in gas chromatography: N-ethoxycarbonyl propylamides and N-trifluoroacetyl ethyl esters of alpha-amino acids on Chirasil-Val-C11 and Chirasil-Dex stationary phases

Inversion of the elution order of enantiomers caused by enthalpy-entropy compensation at the isoenantioselective temperature (Tiso) was experimentally observed by gas chromatography on the diamide-type chiral stationary phase (CSP), Chirasil-L-Val-C11, with N-ethoxycarbonyl propylamide (ECPA) derivatives of a number of alpha-amino acids. For the first time, a clear visual representation of the increase of the apparent enantioseparation factor alpha app from 1.00 to 1.08 as the temperature is raised from 120 to 170 degrees C is presented. The increase of alpha app is accompanied by a concomitant reduction of the retention factors of the enantiomers. The Tiso values were in the range from 110 to 130 degrees C depending on the nature of the alpha-amino acid. On the contrary, the Tiso values of the N(O)-trifluoroacetyl ethyl ester derivatives (TFA-Et) of the same alpha-amino acids were approximately 80 degrees higher than that of ECPA derivatives. The comprehensive thermodynamic investigation of the enantioseparation of ECPA and TFA-Et derivatives of valine and alanine using the retention increment method showed that the Delta L,D(DeltaH) difference between the diastereomeric selector-selectand associates was almost the same for ECPA and TFA-Et derivatives despite a much stronger bonded selector-selectand association taking place for the ECPA derivatives. On the other hand, the Delta L,D(DeltaS) values were found to be more negative in the case of ECPA derivatives, resulting in the unusually low values of Tiso. A temperature-dependent inversion of the elution order of enantiomers was also observed on the cyclodextrin-type CSP, Chirasil-Dex, with TFA-Et derivatives of several alpha-amino acids. The Tiso values were in the range from 20 to 170 degrees C depending on the nature of the alpha-amino acid. The results obtained demonstrate the necessity to conduct temperature-dependent studies in order to optimize the enantiomeric separation of single racemates isothermally or of mixtures of racemates in temperature-programmed runs using enantioselective GC. It is also shown that consideration of the elution order of enantiomers and the value of the apparent enantioseparation factor alpha app alone, without performing temperature-dependent measurements, can easily lead to wrong conclusions regarding the enantiorecognition mechanism.     

Versatile laboratory‐scale polymerization reactor system

A novel lab‐scale reactor system designed for investigation of olefin polymerization reactions using homo‐ and heterogeneous catalysts is introduced. The high inert atmosphere level of the system is based on stainless‐steel lines and cylinders, a nitrogen/vacuum technique, and removable reactants chambers which are packed in a glove‐box. The solvent is transferred straight from the distiller through the reagents' containers into the reactor. The reactor is equipped with an ethylene pressure/mass flow and two temperature‐control systems. Data acquisition is based on a personal computer and software for monitoring and data storage. The results of versatile ethylene copolymerization with cyclopentene, cyclooctene, and cyclododecene with this reactor system are discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2921–2928, 2000     

Compatibilization of polypropylene/poly(n-butylacrylate) blend: Functionalization of the poly(n-butylacrylate) phase by copolymerization

Compatibilization of a polypropylene (PP)/polybutylacrylate (PBuA) blend was studied, with the aim of achieving better adhesion at the interphase through modification of both the PP and PBuA phases. The compatibilization involved two separate stages: First, a small amount (2 and 5 mol %) of functional monomer copolymerizable with and soluble in BuA was added to the BuA initiator solution. Then, this solution was impregnated into PP pellets and polymerized inside the pellets by free-radical polymerization in a water suspension. The resulting blend was a thermoplastic elastomer consisting of PP as the matrix and functionalized PBuA as the partly crosslinked dispersed rubbery phase. The functionalities of the monomers were epoxy, oxazoline, hydroxyl, secondary amine, and carboxyl. In the second stage, two commercial graft copolymers of PP (PP grafted with either acrylic acid or maleic acid anhydride) were blended at the melt stage with the PP/functionalized PBuA blend. Here, the compatibilizing reactions took place between the functionalized components of the blend. The compatilization reactions were detected by FTIR analysis and by changes in mechanical or thermomechanical behavior of the blends. Morphology studies were carried out. As a result, the tensile strength, tensile modulus, elongation at break, and tear strength of the final product were improved by about 15, 20, 160, and 50%, respectively, compared with the unfunctionalized blend. The hardness of the material remained unchanged in the compatibilization. © 1996 John Wiley & Sons, Inc.     

Computational and experimental study of an industrial centrifugal compressor volute

IntrotctionThe overall performance of a centrifugal compressoris a combination of the dueller, diffuser, and voluteperformances. Each component has to be designedcarefully in order tO' minimize the losses and maximizethe efficiency. In this paper, a centrifugal compressorvolute (or spiral) is stUdied numerically, and the CFDresults are compared with measured data.A volute is used to collect the flow from a vaned orvaneless diffuser and to gUide it Ollt of the compressor.The volute geometry…