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  • Degree of neutralization  (1)
  • Measurement techniques: electroencephalography  (1)
  • 1
    ISSN: 1435-1536
    Keywords: Ethylene-acrylic acid copolymer ; Transition metal salts ; Dynamic mechanical properties ; Ion-cluster ; Degree of neutralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Dynamic mechanical properties of ethylene-acrylic acid copolymer (mole% ofAA is 9.3) neutralized with copper(II), manganese(II) and nickel(II) acetates were measured in a temperature range of −150 to 80 °C at 3.5, 11, 35 and 110 Hz. Theβ′ andγ relaxations are observed around 30 and −140 δC, respectively, which are attributed to a micro-Brownian molecular motion of segments and a local molecular motion of short segments, respectively. In theβ′ relaxation, the relaxation temperature increased with increasing degree of neutralization,x, and the peak height decreased, which were independent on the species of counter ions. Theβ relaxation which is ascribed to molecular motion of rather short segments between ion-clusters was observed at high ion concentrations. The effects ofx on theβ′ andβ relaxations were different from those of the preceding dielectric results. This discrepancy between the mechanical and the dielectric results can be explained by the assumption that the segments responsible for the mechanical relaxations are different of those for the dielectric relaxation. In theγ relaxation, the relaxation temperature and the peak height were almost independent ofx and the species of counter ions. The relation between the molecular motion and the structure of the transition metal salts (complex structure and formation of ion-clusters) was understood well by examining the mechanical and dielectrical results together.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-2614
    Keywords: Measurement techniques: electroencephalography ; Metabolism: hypoglycemia ; Brain: electroencephalography ; Hormones: concentrations ; Monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Medicine
    Notes: Abstract Acute insulin-induced hypoglycemia provokes changes in central nervous system activity and release of counterregulatory hormones. The clinical relationship between central nervous system activity, hormone secretion, and vital signs has not to our knowledge been previously reported. We used computerized electroencephalographic (CEEG) analysis to monitor 5 nondiabetic subjects during acute insulin-induced hypoglycemia (0.75 U/kg intravenous push). Their glucose nadir was 38±6 mg/dl (mean ± 1 SD). A three-phase pattern of change in CEEG power in response to hypoglycemia was observed: phase 1 was characterized by an increase in total CEEG power (natural log of activity = 9.1±1.3 µV2) over baseline (8.7±1.2 µV2) in the theta, delta, and beta frequency bands. This phase preceded and coincided with the glucose nadir. During phase 2, power in all frequency bands fell significantly below baseline. A nadir in CEEG power (8.0±1.6 µV2) occurred 40 to 55 minutes after insulin injection as glucose levels were rising. During phase 3 there was a return to baseline in CEEG power and frequency spectra. Heart rate increase just before phase 1; peak heart rate (91±8 beats/min) coincided with peak CEEG power and was significantly higher than basal rate (71±11,P〈0.05). A significant increase in respiratory rate occurred during phase 1 of the CEEG and persisted through phase 2. A significant decrease in mean blood pressure (nadir = 73±6 mm Hg) below preinsulin blood pressure (81±8 mm Hg,P〈0.05) coincided with the nadir of CEEG power in phase 2. Blood pressure returned to basal levels during phase 3. Peak plasma epinephrine (652±207 versus 46±30 pg/ml), norepinephrine (500±219 versus 273±107 pg/ml), and pancreatic polypeptide levels (1,023±689 versus 114±24 pg/ml) were all significantly elevated over respective basal concentrations (P〈0.05). Peak hormone levels occurred during CEEG phase 2. This study demonstrates a temporal association of changes in CEEG power, vital signs, and hormonal secretion. These techniques may be applicable for further investigation of the clinical neuroendocrinology of the response to acute hypoglycemia.
    Type of Medium: Electronic Resource
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