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101.
102.
Jakob PM Wang T Schultz G Hebestreit H Hebestreit A Elfeber M Hahn D Haase A 《Magma (New York, N.Y.)》2002,15(1-3):10-17
The unique characteristics of the human lung arising from low proton density and multiple air-tissue interfaces of the alveoli
cause difficulty in1H lung magnetic resonance imaging. In addition, the dominating signal from sources such as the thoracic muscle and subcutaneous
fat hampers the visualization of the lung parenchyma. In this contribution, an efficient tissue suppression technique is presented
which allows one to significantly enhance lung parenchyma visibility. A short inversion time inversion recovery (STIR) experiment
combined with a magnetization transfer (MT) experiment was used for magnetization preparation in order to suppress the signal
from muscle. A half-Fourier single-shot turbo spin-echo sequence was used as acquisition module. This approach was used to
perform lung anatomical imaging in eight healthy human subjects and five patients withcystic fibrosis. The results obtained demonstrate that with MT-STIR approach high quality human lung images can be obtained and that this
approach has the potential for the evaluation of lung pathologies. 相似文献
103.
(31)P-MR Spectroscopy for the evaluation of energy metabolism in intact residual myocardium after acute myocardial infarction in humans 总被引:1,自引:0,他引:1
Beer M Buchner S Sandstede J Viehrig M Lipke C Krug A Köstler H Pabst T Kenn W Landschütz W von Kienlin M Harre K Neubauer S Hahn D 《Magma (New York, N.Y.)》2001,13(2):70-75
Objective experimental studies have demonstrated that acute myocardial infarction (MI) alters energy metabolism even in non-infarcted
adjacent tissue. In patients with subacute MI, the influence of the regional ischemie insult on energy metabolism of intact
septal myocardium was analyzed using31P-Magnetic resonance spectroscopy (MRS).
Patients and Methods in eight patients with wall motion abnormalities in the anterior wall31P-spectra were obtained from non-infarcted adjacent scptal myocardium, as well as infarcted anterior myocardium (voxel size
25 ccm each) 29 ±8 days after MI using a 3D-CSI technique. Additionally, cardiac function was analyzed using breath-hold cine
MRI. MR1 was repeated 6 months after revascularization to assess viability of infarcted segments. Eight age-matched healthy
volunteers served as control group.
Results according to follow-up MRI 4/8 patients showed regional wall motion recovery. Here, PCr/ATP-ratios were not significantly
reduced in intact septal myocardium as well as infarcted anterior myocardium compared to healthy volunteers (1.28 ±0.10 and
1.14 ±0.09 vs. 1.45 ±0.29). No recovery of regional function was detected in 4/8 patients with —therefore—non-viable anterior
myocardium. PCr/ATP-ratios were significantly reduced in intact and infarcted myocardium compared with healthy volunteers
as well as to patients with wall motion recovery (0.77 ±0.17 and 0.49 ±0.23;P < 0.05).
Discussion these preliminary results indicate that energy metabolism is reduced in patients with persisting wall motion abnormalities
after myocardial infarction and revascularization in ischemically injured as well as in adjacent non-injured myocardium. 相似文献
104.
Schizophrenic patients are extremely heavy tobacco smokers. However, a lower incidence of lung cancer in schizophrenic patients has been observed in comparison to other heavy smokers. Nicotine increases the proliferation of pulmonary neuroendocrine tissue, causing the release of a bombesin-like peptide. Thus, bombesin-like peptide levels in urine may be an indicator of precancerous, cigarette-induced lung damage. Bombesin-like peptide levels of 10 schizophrenic smokers and 11 schizophrenic nonsmokers were compared to those of nonschizophrenic subjects matched for age and pack-years of smoking. The nonschizophrenic smokers showed the expected increase in urinary bombesin-like peptide levels, as compared to nonschizophrenic nonsmokers. Schizophrenic patients had lower bombesin-like peptide levels independent of smoking effects. The mechanism of the difference in bombesin-like peptide levels between schizophrenic patients and nonschizophrenic subjects is unknown, but one possibility involves alteration in the alpha 7-nicotinic acetylcholine receptor, which mediates the growth of some neuroendocrine cell lines in vitro. 相似文献
105.
Duk-Jun Kim Jin-Woo Hahn Gee-Pyeong Han Sang-Seok Lee Tae-Goo Choy 《Journal of the American Ceramic Society》2000,83(4):1010-1012
The sinterability and microwave dielectric properties of (Zr0.8 Sn0.2 )TiO4 with additions of 1 mol% of magnesium, calcium, strontium, or barium were examined. All the alkaline-earth metals were effective for densification, and the order of effectiveness was as follows: Mg < Ca < Sr < Ba. The dielectric constant and the temperature coefficient of the resonant frequency were not influenced very much by the additives; however, a strong deterioration of the quality factor ( Q ) did occur when magnesium was added. The presence of grain-boundary phases was confirmed via microstructural observation, using transmission electron microscopy. In addition, energy-dispersive X-ray analysis was performed to investigate the cause of the deterioration in the Q value. 相似文献
106.
T. Hahn 《Computer Physics Communications》2008,178(3):217-221
This note describes a Mathematica interface for Fortran code generated by FormCalc. The interfacing code is set up automatically so that only minuscule changes in the driver files are required. The interface makes a function to compute the cross-section or decay rate available in Mathematica. This function depends on the model parameters chosen for interfacing in the Fortran code. 相似文献
107.
J. Suffner H. Hahn S. Dosta I.G. Cano J.M. Guilemany 《Surface & coatings technology》2009,204(1-2):149-156
The preparation of nanostructured (ZrO2–5 wt.% Y2O3)–20 wt.% Al2O3 coatings by atmospheric plasma spraying of commercially available micron-scale powders is reported. Materials were prepared by means of a standard spraying technique and by using an improved technique that allows for the quenching of the material using liquid nitrogen-cooled substrates. Quenching leads to the controlled formation of metastable phases. The influence of liquid nitrogen cooling on the formation of the metastable phases was studied by X-ray diffraction under a grazing incidence angle of 1°. A significant increase in the amount of the metastable zirconia phase and a more homogeneous composition along the thickness were found compared to the regularly sprayed coatings. All materials were subjected to a thermal treatment for 1 h at 1400 °C to study the evolution of stable phases. 相似文献
108.
The ageing behaviour of engine test bench and road aged commercial three-way catalysts (TWCs) is compared. Their catalytic performances are tested and the findings are correlated to structural investigations. The TWCs were tested on a chassis dynamometer using the New European Driving Cycle and the catalytic activities were determined by measurements of the oxygen storage capacity and the light-off (LO) temperature. Selected catalysts were characterised by X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray analysing system, nitrogen adsorption (BET) and X-ray fluorescence spectroscopy. A linear increase of the emissions with duration for the HC and CO components and of the LO temperature was observed. A surface area decrease and a growth of Pd particles after ageing could be detected. Also a crystalline BaAl2Si2O8 phase was identified, which can be attributed to a reaction of NO x storage component with cordierite support material. 相似文献
109.
110.
Lim Y. Hahn J. Kim S. Park J. Kim H. Lee B. 《Quantum Electronics, IEEE Journal of》2010,46(3):300-305