Biomedical subjects

W Sitte

Publications and source records attributed to W Sitte.

4 recordsLinked to original sources

PubMed2006

Quantitative model of electrochemical Ostwald ripening and its application to the time-dependent electrode potential of nanocrystalline metals.

The contact of a metastable nanocrystalline metal ensemble with a metal ion electrolyte leads to an electrochemical Ostwald ripening. The kinetics is modeled on the level of irreversible thermodynamics for the case that the rate is controlled by the electrode/electrolyte transfer resistance. In particular, the kinetic behavior of medium-sized particles and the time dependence of the electromotive force is investigated. Even though it is expressed in electrochemical terms (mixed potential), the modeling is also applicable to chemical Ostwald ripening as long as it is interfacially controlled. Under these conditions, the kinetics exhibits, even though not self-accelerating, strong similarities to selection dynamics, with the competition stemming from the cannibalistic nature of the process.

Journal Article↗

PubMed2004

Depression and anxiety in different thyroid function states.

Previous studies on hypothyroid subjects have indicated serious psychiatric symptoms affecting the patients' quality of life. The present prospective cross-sectional study's aim was to examine these symptoms in thyroid patients with different functional states. A total of 254 patients (age: 56 +/- 14 years [mean +/- standard deviation], 181 female, 73 male) referred to a hospital for radioiodine treatment of hyperthyroidism or for follow-up of differentiated thyroid cancer, respectively, were included. All patients underwent the twelve-item general health questionnaire, which is an instrument for detecting mood disturbances. Euthyroid and hyperthyroid patients did not differ significantly in their general health questionnaire score (11 +/- 5 vs. 11 +/- 7), nor did subclinical hyperthyroid (11 +/- 6) or subclinical hypothyroid subjects (12 +/- 5). In contrast, hypothyroid patients showed a significantly higher mean score (17 +/- 7, p < 0.001, ANOVA). Binary logistic regression revealed that hypothyroidism increases age and gender-adjusted risk for critical mood deterioration by seven-fold. Thus, hypothyroidism represents a widely underestimated functional condition that may severely affect mental health.

Adult↗

PubMed2001

Oxygen nonstoichiometry and ionic transport properties of La0.4Sr0.6CoO3-delta .

Homogeneous samples of La0.4Sr0.6CoO3-delta were obtained by the glycine nitrate process. The oxygen nonstoichiometry was determined from oxygen exchange measurements as a function of oxygen partial pressure (10(-4) bar < PO2 < 10(-2) bar) and temperature (300 degrees C < T< 900 degrees C). The chemical diffusion coefficient D was obtained from oxygen exchange measurements applying a stepwise variation of the oxygen partial pressure of the ambient atmosphere of a disk-shaped sample. The amount of oxygen absorbed or desorbed by the perovskite was analyzed as a function of time. Chemical diffusion data were evaluated using simplified and exact fitting procedures taking into account the surface exchange coefficient. Alternatively, galvanostatic polarization measurements were performed in a PO2-range between 10(-4) and 10(-2) bar to yield D and the ionic conductivity sigma(i) from the long time solution of the diffusion equation. Values for D from polarization measurements at T= 775 degrees C and from oxygen exchange measurements at T= 725 degrees C are in good agreement with each other. D and sigma(1) increase with increasing PO2 (10(-4) to 10(-2) bar). The ionic conductivity shows a maximum at 3-delta approximately 2.82 and decreases with decreasing oxygen content indicating the possible formation of vacancy ordered structures.

Kinetics↗

PubMed1996

The glial glutamate transporter complementary DNA in patients with amyotrophic lateral sclerosis.

Here, we report a mutation screening by single-stranded conformational analysis of the astroglial human brain glutamate transporter (HBGT) II complementary DNA in patients with amyotrophic lateral sclerosis. The conformational analysis data indicate a lack of sequence variations in the HBGT II coding region in 6 patients with amyotrophic lateral sclerosis and the same number of nonneurological control subjects. In both groups, three variants of the HBGT II 5' untranslated region were isolated. We have no evidence that the reported complementary DNA variants are disease specific.

ATP-Binding Cassette Transporters↗