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  • General Chemistry  (9)
  • Analytical Chemistry and Spectroscopy  (6)
  • Engineering  (4)
  • GASTRIC ELECTRICAL ACTIVITY  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Comparative Assessment of Power Dynamics of Gastric Electrical Activity (1997)
    Springer
    Digestive diseases and sciences 42 (1997), S. 1154-1157 
    Details
    ISSN: 1573-2568
    Keywords: ELECTROGASTROGRAMS ; GASTRIC ELECTRICAL ACTIVITY ; POWER DYNAMICS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study was undertaken to investigate thecorrelation between power dynamics of gastric electricalactivity (GEA) assessed with different recordingtechniques. A total of seven eight-channel 1-hr combined recordings were obtained from three subjects infive consecutive postoperative days. Four channels wererecorded from bipolar electrodes implanted into thegastric antral wall, and four channels wereelectrogastrographic (EGG). Six pairs of bipolar electrodes wereinserted into the antral wall (three anterior; threeposterior) of 16 anaesthetized dogs. Fourteen-channel(six internal GEA and eight EGG) 1/2-hr recordings were obtained from each dog. Sets of powervalues calculated from channel pairs (internal, EGG ormixed) were cross-correlated and the significance of theobtained correlation coefficients was examined (P 〈 0.05). The majority of powercorrelations of internal GEA channel pairs, and those ofmixed (internal GEA-EGG) channel pairs wereinsignificant. These findings question the claims thatEGG power dynamics mirrors the power dynamics of internalGEA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018829402171
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  • 2
    Electronic Resource
    Electronic Resource
    Dynamics of Level of Randomness of Electrogastrograms Can Be Indicative of Gastric Electrical Uncoupling in Dogs (1999)
    Springer
    Digestive diseases and sciences 44 (1999), S. 523-528 
    Details
    ISSN: 1573-2568
    Keywords: GASTRIC ELECTRICAL ACTIVITY ; ELECTROGASTROGRAPHY ; RANDOMNESS ; GASTRIC ELECTRICAL UNCOUPLING
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Gastric electrical uncoupling is the lack ofelectrical synchronization in different parts of thestomach. The aim of this study was to investigate theimpact of gastric electrical uncoupling on the level of randomness of canine electrogastrograms(EGG). Electrogastrograms were obtained from 11unconscious acute dogs. Gastric electrical uncouplingwas produced surgically by performing two consecutivecircumferential cuts through the entire thickness of thegastric muscle layer. Three separate 1/2-hreight-channel bipolar EGGs were obtained from each dogin the basal state and after each cut. The signals wereamplified using amplifiers with a flexible frequencyrange, digitized with 10-Hz sampling frequency, and4.27-min portions of the digital EGGs weResubjected toa turning point test for randomness. The number of turning points (NTPs) was determined fromsuccessive time intervals calculated from all EGGchannels. Distributions of NTPs were calculated for eachdog. An average NTPs (ANTP) for each dog in a givenstate (basal, after the first cut, and after thesecond cut) was calculated from the ANTPs of allchannels. In six of 11 dogs the ANTP were greater afterthe first cut. The number rose to nine of 11 dogs after the second cut. In only 45% of the dogs werethe ANTP distributions significantly different (P 〈0.01) after the first cut (sensitivity 45%). After thesecond cut the sensitivity rose to 64%. In two specific EGG channels NTP distribution wassignificantly different (P 〈 0.01) in nine of 11 dogs(sensitivity: 82% ) after the second cut. The dynamicsof the level of randomness in EGG can be indicative of severe gastric electrical uncoupling. SomeEGG channel configurations are moResensitive thanoThers in recognizing gastric electricaluncoupling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026697021756
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  • 3
    Electronic Resource
    Electronic Resource
    Dynamics of the Level of Randomness in Gastric Electrical Activity (1998)
    Springer
    Digestive diseases and sciences 43 (1998), S. 953-956 
    Details
    ISSN: 1573-2568
    Keywords: GASTRIC ELECTRICAL ACTIVITY ; ELECTROGASTROGRAPHY ; RANDOMNESS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study was undertaken to investigate thedynamics of the level of randomness in gastricelectrical signals. Combined recordings of internalgastric electrical activity (GEA) and electrogastrograms(EGG) were obtained from 16 unconscious dogs and twopostoperative patients. The signals were amplified usingspecially designed amplifiers with flexible frequencyrange and were digitized with 10-Hz sampling frequency. The 4.27-min portions of the digitalsignals were subjected to a previously described turningpoint test for randomness. The distributions of thenumber of turning points (NTP) in successive time intervals calculated from all GEA signalswere compared to the estimated NTP distribution of arandom signal. NTP dynamics of internal GEA signals wasalso correlated to the NTP dynamics of cutaneous EGG. In five of 16 recordings from the dogs andin two of the 14 recordings from the patients, NTPvalues calculated from some internal GEA channelsexceeded the 1% probability level for entering thenormal NTP distribution of a random signal (P 〉0.01). In all measurements the distributions of the NTPvalues recorded from cutaneous EGG channels weresignificantly different (P 〈 0.01) from the NTPdistribution of a random signal. There was significantcorrelation (P 〈 0.01) between the NTP dynamics ofinternal GEA and EGG. The level of randomness ininternal GEA recorded with the short-distance bipolartechnique is substantially higher than that in cutaneousEGG, probably due to the occurrence of spike activity.Although the level of randomness in EGG is affected bymany external factors, its dynamics correlated significantly with the level of randomness ininternal GEA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018858113172
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  • 4
    Electronic Resource
    Electronic Resource
    Mathematical model for the optimization of the reaction between 2,3-bis(m-tolyl)quinolizinium bromide and piperidine using a factorial design (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 1-10 
    Details
    ISSN: 0886-9383
    Keywords: Derivatization reaction ; Factorial design ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of nucleophiles have been successfully identified and quantified using the Kröhnke reaction with 2,3-diphenyl derivatives of quinolizinium salts. Optimization of the reaction conditions by means of a mathematical model involving analysis of the response surface has led to a better understanding of the factors exerting an influence on the above reaction.The parameters chosen were temperature, reaction time, base concentration, water concentration and nucleophile concentration. The reaction was developed in polar aprotic solvents (acetone, acetonitrile). To facilitate the nucleophilic attack, the presence of an organic base (triethylamine) was necessary, although concentrations in excess of 0·15M did not alter the development of the reaction. Since pharmaceutical solutions are often aqueous, the influence of water on the reaction was studied. Low water volumes have no significant influence on the opening of the quinolizinium ring by the nucleophilic reagent. However, when the water proportion exceeded that of the organic solvent, the fluorescence intensity was lower than expected. Development of the fluorescent reaction product was first detected 5 min after the reaction started. The fluorescence intensity reached its optimum value after 138 min.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180060102
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  • 5
    Electronic Resource
    Electronic Resource
    Enhanced Resolution of Conjugated Linoleic Acid Isomers by Tandem-Column Silver-Ion High Performance Liquid Chromatography (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 144-148 
    Details
    ISSN: 0935-6304
    Keywords: Conjugated linoleic acid (CLA) ; silver-ion high performance liquid chromatography (Ag+-HPLC) ; cheese ; analysis ; silver-ion chromatography ; tandem-column Ag+-HPLC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A commercial mixture of conjugated linoleic acid (CLA) isomers, reportedly consisting of six components, was recently resolved into 12 peaks attributed to CLA isomers using silver-ion high performance liquid chromatography (Ag+-HPLC). In this study, the coupling of two analytical silver-ion high performance liquid chromatography columns (tandem-column Ag+-HPLC) in series led to the enhanced resolution of CLA isomers. Many CLA isomers were baseline resolved and the pair 18 : 2 8,10 c/t and 18 : 2 7,9 c/t found in cheese products, was resolved for the first time. In this work, a similar commercial CLA mixture was separated into 16 peaks, while CLA isomers from cheese also gave rise to 16 peaks. As expected, the CLA isomers were separated into three geometric groups in the order trans,trans, cis/trans, and cis,cis. Semi-preparative Ag+-HPLC, followed by gas chromatography-mass spectroscopy of the dimethyloxazoline derivatives, was used to confirm the identity of the newly resolved positional CLA isomers. The double bond configuration of CLA isomers was established by gas chromatography-Fourier transform infrared spectroscopy. Two minor t,t CLA isomers found in cheese, presumably 18 : 2 t6t8 and 18 : 2 t13t15, were also separated. The CLA isomeric composition of 16 commercial cheese products was determined.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis and Anionically Induced Domino Reactions of Chiral α-Bromo α,β-Unsaturated Esters (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 1569-1576 
    Details
    ISSN: 1434-193X
    Keywords: Asymmetric dihydroxylation (Sharpless-AD) ; Wittig olefination ; α-Bromo α,β-unsaturated esters ; Diastereoselective aprotic Michael domino reaction ; Tricyclo[3.2.1.02,7]octanes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chiral α-bromo α,β-unsaturated esters 3 and 9 are prepared by asymmetric Sharpless dihydroxylation (AD) of 5 and from ester 7 and the chiral diols 8 by transacetalization, respectively. Both types of α-bromo α,β-unsaturated ester react with the kinetic lithium dienolates of enone 10 to give functionalized tricyclo[3.2.1.02,7]octanes 11. Esters 3 give one single diastereomer (de ≥ 95%), whereas mixtures of diastereomers (de 28 to 46%) are obtained with the esters 9.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Matrix-assisted laser desorption ionization for rapid determination of the sequences of biologically active peptides isolated from support-bound combinatorial peptide libraries (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 77-81 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A termination synthesis approach has been developed to encode each resin bead in support-bound combinatorial peptide libraries with the information needed to establish the sequence of the full-length products also contained on the beads. Matrix-assisted laser desorption ionization mass spectrometry was then used to rapidly read the appropriate sequences. In addition to rapid peptide sequencing, the technique allows direct assessment of the quality of the synthetic library, since deletion peptides, side-reaction products and incomplete-deprotection products are readily observed. An anti-gp120 monoclonal antibody was screened against a hexapeptide library, and eight active peptides were isolated. Six of the eight peptides were shown to possess the exact recognition sequence for the antibody.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080115
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  • 8
    Electronic Resource
    Electronic Resource
    Thin layer chromatography/mass spectrometry: The advantages of tandem mass spectrometry (1992)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 6 (1992), S. 608-615 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The results of thin layer chromatography/mass spectrometry (TLC/MS) and thin layer chromatography/tandem mass spectrometry (TLC/MS/MS) experiments are described. Spectra from the analytes were obtained directly from the absorbent without the need for extraction prior to analysis by mass spectrometry. These results illustrate the added specificity that the tandem mass spectrometer can afford in the detection and characterization of a range of compounds separated by TLC.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290061005
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  • 9
    Electronic Resource
    Electronic Resource
    Antisense DNA oligonucleotides II: The use of matrix-assisted laser desorption/ionization mass spectrometry for the sequence verification of methylphosphonate oligodeoxyribonucleotides (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 195-200 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry has been used to measure accurately the molecular masses of synthetic methylphosphonate oligodeoxyribonucleotides, up to 18 nucleotides in length. A simple method has been developed for the complete sequence verification of these compounds, which are intractable by classical means. Sequencing from the 5′ end of the molecule is possible because of inefficiencies in the synthetic procedure. Complementary information from the 3′ end can be obtained by partial hydrolysis of the methylphosphonate backbone.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290070306
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  • 10
    Electronic Resource
    Electronic Resource
    Optimal design of material properties and material distribution for multiple loading conditions (1995)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 38 (1995), S. 1149-1170 
    Details
    ISSN: 0029-5981
    Keywords: material design ; structural optimization ; multiple loads ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An extension of recent work1 on the simultaneous optimization of material and structure to address the design of structures under multiple loading conditions is presented. Material properties are represented in the most general form possible, namely, as elements of the unrestricted set of positive-semi-definite constitutive tensors of a linearly elastic continuum. Existence of solutions can be shown when the objective is a weighted average of compliances and a resource constraint measured as the 2-norm or the trace of the constitutive tensors is included. The optimized material properties can be derived analytically. The optimization of the layout of the material leads to a sizing problem of structural optimization involving a non-linear, non-smooth elasticity analysis. The computational solution of this problem is discussed and illustrated with examples.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620380705
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