Investigation of the interaction of evaporated aluminum with vapor deposited Teflon AF films via X-ray photoelectron spectroscopy

The interfacial bonding and mixing between evaporated aluminum and a vapor deposited Teflon AF (abbreviated to AF) film have been investigated with X-ray photoelectron spectroscopy. Graphite carbon (C–C), and aluminum carbide (Al–C), oxide (Al–O–C) and fluoride (Al–F) are formed when aluminum atoms are deposited on to the AF film. With increasing deposition of aluminum, the concentrations of these newly formed components increase gradually. Moreover, in situ annealing results in remarkable increases in the C–C, Al–C, Al–O–C and Al–F configurations and a decrease in metallic aluminum. No significant diffusion of aluminum into the AF film was observed during the annealing. The Al compounds form a layer at the Al/AF interface that acts as an adhesion promoter and diffusion barrier. Received: 21 October 2002 / Accepted: 22 October 2002 / Published online: 15 January 2003 RID="*" ID="*"Corresponding author. Fax: +49-431/880-6229, E-mail: sjding@yahoo.com     

On the Bifurcation and Stability of Rigidly Rotating Inviscid Liquid Bridges

Summary. We consider a mathematical model that describes the motion of an ideal fluid of finite volume that forms a bridge between two fixed parallel plates. Most importantly, this model includes capillarity effects at the plates and surface tension at the free surface of the liquid bridge. We point out that the liquid can stick to the plates due to the inner pressure even in the absence of adhesion forces. We use both the Hamiltonian structure and the symmetry group of this model to perform a bifurcation and stability analysis for relative equilibrium solutions. Starting from rigidly rotating, circularly cylindrical fluid bridges, which exist for arbitrary values of the angular velocity and vanishing adhesion forces, we find various symmetry-breaking bifurcations and prove corresponding stability results. Either the angular velocity or the angular momentum can be used as a bifurcation parameter. This analysis reduces to find critical points and corresponding definiteness properties of a potential function involving the respective bifurcation parameter. Received June 21, 1996; revision received October 2, 1997, and accepted for publication October 9, 1997     

Sociodemographic variables of a german sample of patients with contact granuloma

We report 28 German patients with contact granuloma (27 male, 1 female). Their mean age was 52 years (ranging from 35 to 70). Thirty-two percent were retired. The occupations of the others represented a wide range of different jobs. The majority of the sample had a middle educational level. Most patients lived with their family or with a partner. According to self-assessments, 68% had average daily strain on their speaking voice. All patients were nonsmokers. The patients felt themselves more disturbed by somatic troubles as the general population. Heartburn was felt by nearly half of the patients. A little more than half of the patients suffered from globus sensation. Thus, it is not possible at present to explain the laryngeal contact granuloma by sociodemographic data, vocal stress, or special somatic complaints in this sample. Therefore a multifactorial etiology should be supposed.     

Quantitative mass spectrometry in clinical chemistry

As has been demonstrated, mass spectrometry provides a powerful analytical tool for the accurate measurement of small amounts of substances in a complex biological matrix. In our laboratory this technique is used as a reference method for measuring the routine clinical chemical parameters creatinine, uric acid, cholesterol, total glycerol and the hormones cortisol, testosterone, oestradiol-17β, oestriol, progesterone, aldosterone and thyroxine in human serum. In general, the analytical procedure for measuring a substance by isotope dilution mass spectrometry (IDMS) consists of the following steps:

1. Addition of a certain amount of the isotopically labeled analyte to the serum sample.
2. Isolation and purification of the labeled and the non-labeled endogenous analyte from the biological matrix.
3. Derivative formation of the isolated and purified labeled and non-labeled compound.
4. Selected ion recording of characteristicm/z values of the labeled and non-labeled analyte using combined gas chromatography-mass spectrometry (GCMS).
5. Calculation of the concentration of the analyte from the isotope ratio measured by GCMS.

The methods described here are now routinely in use for the quality control scheme of the Deutsche Gesellschaft für Klinische Chemie for assessing target values in external quality control sera. The reference method values obtained by IDMS provide a reliable basis for evaluating and comparing the results of collaborative surveys.     

Cytokine production after helium-neon laser irradiation in cultures of human peripheral blood mononuclear cells.

The effects of laser light on the immune system have not been extensively characterized. Low-power laser sources, such as the helium-neon (He-Ne) laser with a wavelength of 632.8 nm, have been found to produce photobiological effects with evidence of interference with immunological functions. We have investigated the effects of He-Ne laser irradiation on Ficoll-Hypaque-isolated human peripheral blood mononuclear cells (PBMC). Cultured cells were irradiated for various times at two selected intensities and then stimulated with different mitogens. The rate of incorporation of 3H-thymidine into the DNA of stimulated cells decreased with increasing energy density. The levels of interleukin-1 alpha (IL-1 alpha), interleukin-2 (IL-2), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) in supernatants of the cultures were determined (irradiated either before or after stimulation). When stimulating cells after irradiation, significantly increased levels of all cytokines were detected after 30 min of irradiation (18.9 J cm-2), whereas after 60 min of irradiation (37.8 J cm-2) cytokine levels were found to be significantly decreased.