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  • 1995-1999  (16)
  • 1980-1984  (2)
  • Polymer and Materials Science  (10)
  • ELECTROGASTROGRAPHY  (4)
  • Engineering General  (3)
  • Electrogastrogram
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Material
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Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Gastric Myoelectrical Activity in Healthy Children and Children with Functional Dyspepsia (1998)
    Springer
    Digestive diseases and sciences 43 (1998), S. 2384-2391 
    Details
    ISSN: 1573-2568
    Keywords: ELECTROGASTROGRAPHY ; FUNCTIONAL DYSPEPSIA ; GASTROINTESTINAL MOTILITY ; GASTRIC EMPTYING
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was to investigateabnormalities in pediatric patients with functionaldyspepsia. Fifteen symptomatic pediatric patientsdiagnosed with functional dyspepsia and 17 aged-matchedhealthy controls were studied. Gastric myoelectricalactivity was recorded using surface electrogastrographyfor 1 hr in the fasting state and 1 hr after a testmeal. It was found that, in comparison with thecontrols, the children with functional dyspepsia had alower percentage of 2- to 4-cpm slow waves in bothfasting state (66.0 ± 4.7% vs 79.7 ± 3.1%,P 〈 0.07) and fed state (72.4 ± 5.4% vs 85.0± 2.9%, P 〈 0.04), and a significantly higherinstability of the dominant frequency in both fastingstate (0.50 ± 0.05 vs 0.31 ± 0.04, P 〈0.01) and fed state (0.39 ± 0.05 vs 0.25 ±0.03, P 〈 0.05). It was also found the postprandial increase inEGG dominant power in the patients was inverselycorrelated with the total symptom score (r = 0.63, P =0.03). It was concluded that abnormal gastricmyoelectrical activity may play a role in the pathogenesis ofpediatric functional dyspepsia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026661627304
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  • 2
    Electronic Resource
    Electronic Resource
    Efficiency and Efficacy of the Electrogastrogram (1998)
    Springer
    Digestive diseases and sciences 43 (1998), S. 1023-1030 
    Details
    ISSN: 1573-2568
    Keywords: ELECTROGASTROGRAPHY ; GASTROINTESTINAL MOTILITY ; GASTRIC EMPTYING ; STOMACH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The efficiency and efficacy of theelectrogastrogram (EGG) involve a few practical factors,including recording length, sample size, and thecharacteristics of subjects. The aim of this study wasto investigate the effect of these factors on the accuracy ofEGG analysis. Gastric myoelectrical activity wasrecorded using electrogastrography in 24 subjects (ages22-91 years) for 1 hr in the fasting state and 2 hr after a test meal. Computerized spectralanalysis was performed to compute EGG parameters,including dominant frequency, dominant power, and thepercentage of 2-4 cycles per minute (cpm) slow waves. A parameter called misinterpretation was definedto investigate the effect of recording length. Theresults were as follows: (1) Using the recording lengthof 1 hr in each state as a gold standard, themisinterpretation for the recording length of 30 min was 27% forthe dominant frequency and 17% for the dominant power.When the recording length was reduced to 15 min, themisinterpretation increased to 61% for the dominant frequency and 38% for the dominant power. (2)With a sample size of 10 subjects and a recording lengthof 60 min, a statistically significant postprandialincrease was observed in the dominant frequency and power, and a trend in the postprandialincrease of the regularity of the EGG was noted. Whenthe sample size increased to 24 subjects, a significantpostprandial increase was found in all these parameters. (3) None of the EGG parameters exhibited anysignificant difference between the younger and oldersubjects or between men and women. In conclusion, arecording length of 30-60 min seems to be appropriate and produces reliable and predictable results.Age and gender do not affect any of the EGGparameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018830801785
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  • 3
    Electronic Resource
    Electronic Resource
    Impaired Postprandial Gastric Slow Waves in Patients with Functional Dyspepsia (1998)
    Springer
    Digestive diseases and sciences 43 (1998), S. 1678-1684 
    Details
    ISSN: 1573-2568
    Keywords: ELECTROGASTROGRAPHY ; GASTROINTESTINAL MOTILITY ; FUNCTIONAL DYSPEPSIA ; GASTRIC EMPTYING
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was to investigate gastricmyoelectrical activity in patients with functionaldyspepsia. Thirteen healthy subjects and 14 patientswith functional dyspepsia participated in the study. The electrogastrogram (EGG) recording was madein each subject for 30 min in the fasting state and 120min after a standard test meal of 475 calories. Spectralanalysis methods were applied to derive quantitative EGG parameters. There was no difference in theEGG between the patients and controls in the fastingstate. However, abnormalities in the postprandial EGGwere found in the patients. The percentage of 2-4 cpmwaves was significantly lower (74.4 ± 4.0% vs85.7 ± 1.6%, P 〈 0.03) and the postprandialincrease in EGG dominant power was significantly less(–0.52 ± 0.92 dB vs 2.24 ± 0.88 dB,P 〈 0.03) in patients than in controls. It was alsofound that the percentage of postprandial 2-4 cpm wavescould be used to differentiate the patients withfunctional dyspepsia from the healthy controls with a specificity of 100% and a sensitivity of 43%. It was concluded that a subset of patients withfunctional dyspepsia have impaired gastric myoelectricalactivity in the fed state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018806913907
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of Electroacupuncture on Gastric Migrating Myoelectrical Complex in Dogs (1999)
    Springer
    Digestive diseases and sciences 44 (1999), S. 56-62 
    Details
    ISSN: 1573-2568
    Keywords: GASTRIC SLOW WAVES ; GASTRIC MOTILITY ; GASTRIC EMPTYING ; ELECTROACUPUNCTURE ; ELECTROGASTROGRAPHY
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was to investigate thecharacteristics of the gastric slow wave duringdifferent phases of the migrating myoelectrical complex(MMC) and the effect of electroacupuncture on the MMC. The experiment was performed in eight hounddogs implanted with one pair of bipolar serosalelectrodes 2 cm proximal to the pylorus. Gastricmyoelectrical activity was recorded for three completecycles of the MMC in two sessions, one withelectroacupuncture at points ST36 and PC6 and the otherat sham points. The acupuncture was performed for 30 minin phase I of the second cycle of the MMC. Spectral analysis was performed to compute the frequencyand power (amplitude) of the gastric slow wave, whereasblind visual analysis was applied to compute theappearance of spike potentials and the length of each phase of the MMC. It was found that therewas a significant difference in the frequency and powerof the gastric slow wave during different phases of theMMC (P 〈 0.05). Phase I was characterized with the highest frequency and lowest power ofthe gastric slow wave, whereas phase III exhibited thehighest power in the slow wave. It was also found thatin comparison with the sham points, electroacupuncture at the acupoints increased the number of spikebursts. This increase was not significant during the MMCcycle with electroacupuncture (34.4 ± 4.1 vs 27.5± 2.5%, P 〉 0.05) but became significant during the cycle after electroacupuncture (39.8± 3.3% vs 27.5 ± 2.5%, P 〈 0.0005).Similarly, during the MMC cycle after electroacupunctureat the acupoints, there was a significant decrease in the length of phase I (14.8 ± 2.2 vs46.9 ± 6.1 min, P 〈 0.003) and a significantincrease in the length of phase II (75.6 ± 9.9 vs30.6 ± 4.1 min, P 〈 0.003) and phase III (25.8± 0.6 vs 22.1 ± 0.7 min, P 〈 0.003). A similarincrease was observed during the MMC cycle withelectroacupuncture but was not statisticallysignificant. In conclusion, the gastric slow wave hasthe highest power during phase III of the MMC, indicatingthat the antral contraction is characterized not only bythe appearance of spikes, but also by the increasedpower of the slow wave. Electroacupuncture at acupoints of ST36 and PC6 enhances the gastric MMC byreducing the length of phase I and increasing the lengthof phases II and III.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026645931867
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis and properties of copolymers from 2-hydroxyethyl methacrylate-linked nonsteroidal antiinflammatory agents with methacrylic acid (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1481-1490 
    Details
    ISSN: 0887-624X
    Keywords: ibuprofen ; ketoprofen ; naproxen ; copolymer reactivity ; thermal stability ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three nonsteroidal antiinflammatory drugs, 2-(4-isobutylphenyl)-propionic acid (ibuprofen), 2-(3-benzoylphenyl)-propionic acid (ketoprofen), and 2-(6-methoxy-2-naphthyl)-propionic acid (naproxen), were covalently linked with 2-hydroxyethyl methacrylate (HEMA). The drug-linked HEMA (M1) (ibuprofen-linked HEMA abbreviated as HI; ketoprofen-linked HEMA as HK, and naproxen-linked HEMA as HN), were respectively copolymerized with methacrylic acid (M2), MA, to obtain macromolecular prodrugs. The compositions of the copolymers were determined by means of a 1H-NMR spectroscopy and monomer reactivity ratios were estimated using the Kelen-Tüdös linear differential equation. The reactivity ratios are: r1 = 0.101 ± 0.012, r2 = 1.071 ± 0.065 for HI-MA; r1 = 0.344 ± 0.066, r2 = 0.966 ± 0.032 for HN-MA, and r1 = 0.650 ± 0.182, r2 = 1.032 ± 0.106 for HK-MA, respectively. The monomer reactivity toward to MA radical estimated from 1/r2 values is almost same for all three monomers (1/r2 ∼ 1). The glass transition temperatures of three drug-linked homopolymers go hand in hand with the steric hindrance of three drugs, i.e., ketoprofen 〉 naproxen ≫ ibuprofen calculated the minimum energy by computer molecular modeling. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1481-1490, 1998
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Optimized Overcomplete Signal Representation and its Applications to Time-frequency Analysis of Electrogastrogram (1998)
    Springer
    Annals of biomedical engineering 26 (1998), S. 859-869 
    Details
    ISSN: 1573-9686
    Keywords: Spectral analysis ; Matching pursuit ; Stomach ; Gastric motility ; Electrogastrography ; Evolutionary programming ; Signal analysis ; Electrogastrogram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The electrogastrogram (EGG) is a surface measurement of gastric myoelectrical activity. The normal frequency of gastric myoelectrical activity in humans is 3 cycles/min. Abnormal frequencies in gastric myoelectrical activity have been found to be associated with functional disorders of the stomach. The aim of this article was, therefore, to develop new time-frequency analysis methods for the detection of gastric dysrhythmia from the EGG. A concept of overcomplete signal representation was used. Two algorithms were proposed for the optimization of the overcomplete signal representation. One was a fast algorithm of matching pursuit and the other was based on an evolutionary program. Computer simulations were performed to compare the performance of the proposed methods in comparison with existing time-frequency analysis methods. It was found that the proposed algorithms provide higher frequency resolution than the short time Fourier transform and Wigner-Ville distribution methods. The practical application of the developed methods to the EGG is also presented. It was concluded that these methods are well suited for the time-frequency analysis of the EGG and may also be applicable to the time-frequency analysis of other biomedical signals. © 1998 Biomedical Engineering Society. PAC98: 8780+s, 0705Kf
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1114/1.69
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  • 7
    Electronic Resource
    Electronic Resource
    Study of the dielectric properties of ferroelectric liquid crystals and related side chain liquid crystalline polymers (1995)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 196 (1995), S. 2601-2614 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Broadband dielectric spectroscopy (frequency range 10-1-106 Hz) was used to analyze the frequency and temperature dependence of the molecular dynamics of a series of ferroelectric liquid crystals (FLCs) and polymers which exhibit a chiral smectic C (SC*) phase in a wide temperature range (about 190°C) including room temperature. Two ferroelectric modes, Goldstone and Soft mode, were observed in the low-molar-mass FLCs. Both of these modes were found in the SC* phase; however, only the soft mode was present in the smectic A (SA) phase. On the other hand, two collective relaxation processes (Soft and Goldstone mode) and four molecular relaxations (δ, α, β and γ-relaxation) of the side chain liquid crystalline polymer were demonstrated.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1995.021960813
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  • 8
    Electronic Resource
    Electronic Resource
    Ultrasonic devulcanization of rubber vulcanizates. I. Process model (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 59 (1996), S. 803-813 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Tire and rubber waste recycling is an important issue facing the rubber industry. In addressing this issue, the present article describes the first attempt to formulate a model and to simulate a novel continuous ultrasonic devulcanization process. The proposed model is based upon a mechanism of rubber network breakup caused by cavitation, which is created by high-intensity ultrasonic waves in the presence of pressure and heat. Dynamics of bubble behavior is described by the Notlingk-Neppiras equation with incorporation of an additional term based upon elastic strain-energy potential. Acoustic pressure arising in the ultrasonic field is related to void formation. Their concentration is calculated based upon nucleation and growth of gas bubbles in crosslinked elastomers under negative driving pressure. The breakup of a three-dimensional network in crosslinked rubbers is combined with flow modeling. The viscosity function required for this modeling is based upon a power-law model which includes temperature, shear rate, and gel fraction dependence. © 1996 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Ultrasonic devulcanization of rubber vulcanizates. II. Simulation and experiment (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 59 (1996), S. 815-824 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The simulation results based on the devulcanization model presented in Part I of this study are described for devulcanization of SBR vulcanizates. The vulcanizates are conveyed by a single-screw extruder to a thin gap between a stationary die and a vibrating horn. Gapwise velocity, temperature, and shear-rate distributions along the die length are calculated. Predictions of the model for changes of various structural characteristics including gel fraction, fraction of various broken bonds, rate of their breakup, and void formation along die length are given. Devulcanization energy consumption and energy dissipated by ultrasonic waves are calculated. Comparison of these energies indicates that the devulcanization energy represents only a small fraction of the dissipated energy. The predicted results for gel fraction, crosslink density, die characteristics, and “mixing cup” temperature are compared with the experimental data. These predicted results are found to be only in qualitative agreement with experimental observations. The theoretical and experimental results indicate that the rubber is partially devulcanized and the devulcanization process is accompanied by some degradation of the macromolecular chains. © 1996 John Wiley & Sons, Inc.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Preparation of gradient-index (GRIN) polymer fibers for imaging applications (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 60 (1996), S. 1379-1383 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A closed extrusion process combined with a core-shell separation die design is developed in this study for preparing gradient index (GRIN) polymer fibers with a quadratic distribution of the refractive index. The material system used in this investigation is methyl methacrylate (MMA, n = 1.49) and benzyl methacrylate (BzMA, n = 1.568). The refractive index differences between the center and the periphery (Δn) of the prepared polymer fibers increase from 0.0115 to 0.020 when BzMA in the reactant mixtures increases from 17 to 28%. This finding would suggest that increasing the high refractive index monomer in the reactant mixture increased Δn. The Δn values decrease from 0.018 to 0.0135 when the diffusion zone temperature increases from 70 to 90°C. The diffusion rates of the monomers increase with the temperature, thereby causing BzMA and MMA to distribute more uniformly at a higher temperature than at a lower one. This uniform distribution leads to the decrease of Δn with an increasing temperature. The prepared GRIN polymer fibers have potential applications as imaging lenses for scanners, fax machines, and copiers. © 1996 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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