Biomedical subjects

D Blaser

Publications and source records attributed to D Blaser.

4 recordsLinked to original sources

PubMed2005

[Bavarian mammography screening program].

In Bavaria since the 1st April 2003 we have been conducting a high quality mammography-screening carried out in individual practises (BMS). We have used the European and the S 3 guidelines. The best diagnosis is an early diagnosis of the breast carcinoma to save human life. Because of this and the high mortality rate due to this disease it is essential to have a mammogram screening program. There is no single one ideal way of constructing a screening program, it is always based on compromise within the particular health care-systems. Arising problems cannot be avoided, it is only possible when all parties work closely together that the BMS works properly.

Breast Neoplasms↗

PubMed2004

[Bavarian mammography screening: results of consistency tests in X-ray units over three months].

PURPOSE: To find out whether the quality requirements in daily, weekly or monthly tests of the "European protocol for the quality control of the physical and technical aspects of mammographic screening (EPQC)" can be maintained when screening the population of a large area. Furthermore, to check the specific tolerances of different test positions given by the EPQC for redundancy and statistical correlation. MATERIALS AND METHODS: Daily test images were obtained with an additional exposition of a sensitometric step wedge according DIN 6868 - 2. Weekly densitometry and visual inspection were performed at the University of Applied Sciences, Cologne. RESULTS: All units were able to maintain basic requirements on image quality as long as films of the same batch number were used. Some tolerance requirements of the EPQC are inconsistent and redundant. CONCLUSION: The occasionally considerable fluctuations of film processing require a daily check on the processing conditions. Daily test images of the units are only obligatory in the first 4 to 5 weeks of a new operation. All test results should be analyzed retrospectively in an independent test laboratory with emphasis on the statistical behavior of the unit. The tolerances prescribed by the EPQC are not always consistent and should be adapted to today's scientific standard when applied in mammography screening centers.

Female↗

PubMed2000

Programmed construction of discrete self-assembled cyclic aggregates

Examples for programmed self-assembly of alpha,beta-unsaturated ketoximes carrying a terminal pyridine subunit are described. The solid-state structures of a series of pyridinyl alpha,beta-unsaturated ketoximes 1 were investigated by X-ray structural analysis; this demonstrated that molecules 3-5 predictably form discrete cyclic aggregates stabilized by a network of hydrogen bonds and aromatic interactions.

Journal Article↗

PubMed2000

Experimental and theoretical investigations on the synthesis, structure, reactivity, and bonding of the stannylene-iron complex Bis bis(2-tert-butyl-4,5,6-trimethyl-phenyl)SnFe (eta6-toluene) (Sn-Fe-Sn)

The pi-(arene)bis(stannylene) complex bis(bis(2-tert-butyl-4,5,6-trimethylphenyl)SnFe(eta6-toluene) (Sn-Fe-Sn, 15) is accessible in high yields by a metal-atom-mediated synthesis between iron atoms, toluene, and the stannylene [bis(2-tert-butyl-4,5,6-trimethylphenyl)Sn](3). Complex 15 has a half-sandwich structure with short Fe -Sn bonds (2.432(1) A) and a trigonal-planar coordination at both the Fe and Sn atoms. The distance between the two Sn centers is 3.56 A. Complex 15 is stable under ambient conditions and displays a pi-arene lability, so far rarely observed for (arene)iron complexes; this leads to an irreversible substitution of the arene and formation of fivefold-coordinated zerovalent iron complexes. The pi-arene lability of the title compound is a result of the Fe-Sn bonding situation, which can be interpreted, on the basis of an extended Huckel molecular orbital calculation, as being solely a donation of the 5sigma lone-pair of Sn into empty or half-filled acceptor d orbitals on Fe. As the calculations reveal, there is little backbonding from the iron to the tin, and the strong sigma donation leads to an increased occupation of the pi-antibonding orbitals of the eta6-arene, which are mainly responsible for the experimentally observed arene lability. Fe and Sn Mossbauer spectra support the polar character of Sn(sigma+)-->Fe(sigma-) with strong sigma donation from tin to iron, but significantly low iron-to-tin pi backdonation.

Journal Article↗