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S Welter

Publications and source records attributed to S Welter.

8 recordsLinked to original sources
PubMed2003

Electroluminescent device with reversible switching between red and green emission.

Research on new materials for organic electroluminescence has recently focused strongly on phosphorescent emitters, with the aim of increasing the emission efficiency and stability. Here we report the fabrication of a simple electroluminescent device, based on a semiconducting polymer combined with a phosphorescent complex, that shows fully reversible voltage-dependent switching between green and red light emission. The active material is made of a polyphenylenevinylene (PPV) derivative molecularly doped with a homogeneously dispersed dinuclear ruthenium complex, which fulfils the dual roles of triplet emitter and electron transfer mediator. At forward bias (+4 V), the excited state of the ruthenium compound is populated, and the characteristic red emission of the complex is observed. On reversing the bias (-4 V), the lowest excited singlet state of the polymer host is populated, with subsequent emission of green light. The mechanism for the formation of the excited state of the PPV derivative involves the ruthenium dinuclear complex in a stepwise electron transfer process that finally leads to efficient charge recombination reaction on the polymer.

Journal Article↗
PubMed2001

[Pulmonary blastoma--a rare malignant lung tumor].

Pulmonary blastoma is a rare non-small-cell lung cancer. In a statistically significant proportion of cases it is combined with cystic lung disease in children. The biphasic pulmonary blastoma and the well-differentiated fetal adenocarcinoma are the most frequent manifestations of pulmonary blastoma. If metastatic disease is ruled out, surgical therapy should be guided by the principles for radical therapy of NSCLC. There are no sufficient recommendations yet for therapy of stage IIIb and IV (UICC 1997) disease.

Aged↗
PubMed1997

High-risk obstetric patients. Maternal morbidity after cesareans.

OBJECTIVE: To assess maternal morbidity associated with cesarean delivery among high-risk obstetric patients in a private practice setting. STUDY DESIGN: Maternal outcome parameters were prospectively studied in 1,000 consecutively delivered patients over a one-year period. RESULTS: Three hundred forty-one patients (34%) delivered by cesarean; 194 of the procedures were performed without labor. The incidence of febrile morbidity and wound infection in patients undergoing cesarean delivery without labor, 0.5%, was no greater than that of patients who delivered vaginally (P = 1.0). There was a higher incidence of transfusion in patients delivered by cesarean without labor, but these patients were more likely to have preoperative anemia (P = .036). Patients undergoing cesarean with labor or ruptured membranes had an increased incidence of both febrile morbidity (P = .023) and wound seroma (P = .008). CONCLUSION: Maternal morbidity following cesarean delivery in high-risk obstetric patients in a private practice setting is low.

Cesarean Section↗
PubMed1996

Factors predicting successful labor induction.

OBJECTIVE: To evaluate maternal parity, the sonographic measurement of cervical length, and the five components of the Bishop score to determine which factors best predict the length of latent-phase labor in women undergoing labor induction. METHODS: Cervical position, cervical consistency, cervical effacement, cervical dilation, station of fetal presenting part, maternal parity, and sonographic measurement of cervical length were studied prospectively in 109 women undergoing labor induction. A multiple regression model was used to determine which factors best predict the length of latent-phase labor. RESULTS: A model using these seven factors was predictive in determining the number of hours of latent-phase labor (F = 32.1, P < .001). Backward stepwise multiple linear regression indicated that only cervical dilation independently predicted the length of latent-phase labor. There was a significant correlation between the clinical assessment of cervical effacement and the sonographic estimation of cervical length, (r = -0.523, P < .001). CONCLUSION: Only cervical dilation appears to predict the length of latent-phase labor. The sonographic evaluation of cervical length and maternal parity do not add significant independent information.

Cervix Uteri↗
PubMedDate not supplied

Observations on the sonographic measurement of cervical length and the risk of premature birth.

OBJECTIVE: There is increasing evidence that sonographic measurement of cervical length may be a useful predictor of the risk of spontaneous premature birth. The purpose of this study is to determine whether the measurement of cervical length in a high-risk population at 24 weeks gestation, or the relative change over 24-28 weeks gestation, is more accurate in predicting the risk of spontaneous preterm birth before 35 weeks gestation. METHODS: Over a 4-year period from 1993-1996, 443 patients with a singleton pregnancy who were at increased risk of preterm birth were studied by serial endovaginal sonography performed at 24 and 28 weeks gestation. RESULTS: There was a positive association between a short cervix and increased risk of preterm birth (F = 13.3, P < .0001). The variable with the highest predictive value for preterm birth was the cervical length at 24 weeks gestation. Changes over time did not substantially improve the predictive accuracy for spontaneous preterm birth. CONCLUSIONS: We conclude that a short cervix as determined by endovaginal sonography has a significant association with preterm birth in a high-risk obstetric population. Measurements taken at 24 weeks gestation are most accurate in assessing this risk, and serial observations of the cervix over time have less accuracy for predicting preterm birth.

Adult↗