Search Results - (Author, Cooperation:W. Geerts)

2011-10-04

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Ammonia/metabolism ; *Anaerobiosis ; Atmosphere/chemistry ; Bacteria, Anaerobic/metabolism ; Biocatalysis ; Hydrazines/metabolism ; Nitrate Reductase/metabolism ; Nitric Oxide/biosynthesis/metabolism ; Nitrites/metabolism ; Nitrogen Cycle ; Nitrogen Fixation ; Oxidation-Reduction ; Quaternary Ammonium Compounds/chemistry/*metabolism

1077-3118

AIP Digital Archive

Physics

High-quality thin-film of NiMnSb with the Clb crystal structure can be grown by low-power sputtering, at substrate temperatures as low as 250 °C. Structural and magneto-optical properties of these films are similar to those of bulk material prepared at high temperatures, which suggest that the predicted 100% spin-polarized behavior of NiMbSb may also be found in these films. The magneto-optical Kerr spectra have been measured, and they are found to be very sensitive to the preparation condition. The spectrum of the bulk alloy is closely reproduced only in the case of optimized films. This suggests that, in the optimized case, the electronic band structure is bulklike. © 1997 American Institute of Physics.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

A magneto-optical (MO) Kerr tracer based on an ellipsometer was developed for studying the surface magnetic properties of thin films. This system can be used to measure the optical properties n and k, which are strongly related to the magneto-optical parameters θk and ηk. In order to carry out measurements on materials having a small θk we have developed a multiple reflection sample holder which gives an enhancement of the rotation. The behavior of the sample holder is explained in terms of Jones matrices. The optical and magneto-optical properties for a thickness series of Co-Cr films were measured. Comparative measurements on other systems gave similar results.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

An intensity oscillation of the saturation polar Kerr rotation φK due to interlayer thickness d was observed in Fe(5 A(ring))/Au(d A(ring))/Fe(5 A(ring))(100) and Fe(6 A(ring))/Au(d A(ring))/Fe(6 A(ring))(100) sandwiched films. The periods of the oscillation are about 7–8 and 5–6 monolayers of Au thickness, respectively. The oscillation of φK can be observed only in the photon energy range 2.5–3.8 eV for Fe(6 A(ring))/Au(d A(ring))Fe(6 A(ring)). These phenomena are considered to be closely related to a formation of spin-polarized quantum-well states of the minority Δ1 band in the Au layer sandwiched with two Fe barrier layers. The φK peak positions and oscillation period do not correspond exactly to those of the change in the in-plane saturation field Hs.

Electronic Resource

0304-4165

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Chemistry and Pharmacology

Medicine

Physics

Electronic Resource

0304-8853

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Physics

Electronic Resource

0304-8853

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Physics

Electronic Resource

1432-0568

Myosin heavy chain ; Immunohistochemistry ; Heart development ; Conductive tissue ; Pattern formation

Springer Online Journal Archives 1860-2000

Medicine

Summary The 3-D distribution of atrial and ventricular isomyosins is analysed in tubular chicken hearts (stage 12+ to 17 (H/H)) using antibodies specific for adult chicken atrial and ventricular myosin heavy chains, respectively. At stage 12+ (H/H) all myocytes express the atrial isomyosin; furthermore, all myocytes except those originally situated in the dorsolateral wall of the sinu-atrium coexpress the ventricular isomyosin as well. Moreover, it appears that recently incorporated myocardial cells at both ends of the heart tube start with a coexpression of both isomyosins. From stage 14 (H/H) onwards a regional loss of expression of one of either isomyosins is observed in the atrial and ventricular compartment. In this way the single isomyosin expression types that are characteristic for the adult working myocardium of the atria and ventricles arise. So, the isomyosin expression patterns are, unexpectedly, hardly useful to discriminate the different heart parts of the tubular heart. The ventricle, defined by its adult type of isomyosin expression, is even not detectable before stage 14 (H/H). Interestingly, interconnected coexpression areas, which may be precursor conductive tissues, are still present at stage 17 (H/H) in the outflow tract, the ventricular trabeculae, the atrio-ventricular transitional zone and in the sinuatrium. The pattern of isomyosin coexpression was found to correlate with a peristaltoid contraction and a slow conduction velocity, whereas single expression areas correlate with a synchronous contraction and a relatively fast conduction velocity. The possible implications of the changing isomyosin pattern for the differentiation of the tubular myocardium, in particular in relation to the development of the conductive tissues, will be discussed.

Electronic Resource

1432-0568

Chicken heart ; Conduction system ; Immunohistochemistry ; Myosin isoforms ; Development

Springer Online Journal Archives 1860-2000

Medicine

Summary The development of the ventricular conducting tissue of the embryonic chicken heart has been studied using a previous finding that morphologically recognizable atrial conducting tissue coexpresses the atrial and the ventricular myosin isoforms. It is found that, by these criteria, at 9 days part of the ventricular conduction system consists of a myocardial ring located around the infundibula of the aorta and truncus pulmonalis. Part of this ring is formed by the retro-aortic root branch. The ring continues via the septal branch into the atrioventricular bundle and its branches, that all express both myosin isoforms. The retroaortic root branch could be traced back as a part of the myocardial wall of the truncus arteriosus at the 4 days embryonic stage. At the 16th day of development, the septal branch, atrioventricular bundle and left and right bundle branches no longer express the atrial isomyosin, but two bundles originating from the septal branch still express both isomyosins, one being the retro-aortic root branch, the other being only immunologically recognizable and directed to the ventral side of the truncus pulmonalis; this latter we call the pulmonary root branch. Both bundles are remnants of the myocardial ring.

Electronic Resource

1573-6865

Springer Online Journal Archives 1860-2000

Biology

Medicine

Abstract The present review provides a starting point for setting up an image analysis system for quantitative densitometry and absorbance or fluorescence measurements in cell preparations, tissue sections or gels. Guidelines for instrumental settings that are essential for the valid application of image analysis in cytophotometry and cytofluorometry are described. The general principles of the working mechanism of CCD cameras in combination with general methods to improve the behaviour of the cameras are presented. Optimization of illumination of microscopical and macroscopical objects receives special attention because of its importance for valid cytometry. Sources of errors in quantitative measurements are listed and step-by-step charts for tuning the CCD camera, frame grabber and illumination for the optimal use of the systems are described. Suggestions are given for improvement of image arithmetics in difficult imaging situations, such as low fluorescence signals and high absorbance signals

Electronic Resource

0003-276X

Life and Medical Sciences ; Cell & Developmental Biology

Wiley InterScience Backfile Collection 1832-2000

Medicine

Three-dimensional (3-D) distribution of atrial and ventricular isomyosins is analysed immunohistochemically during the formation of the tubular chicken heart (stage 7 to 12 [H/H]) using antibodies specific for adult chicken atrial and ventricular myosin heavy chains, respectively. This analysis revealed that both types of isomyosins can be first detected at stage 8 (H/H, possessing four pairs of somites), i.e., when the heart primordium still exists as two separate cardiogenic plates. The ventricular type of isomyosin is initially expressed in those areas of cardiogenic plates in the vicinity of the anterior intestinal portal. The atrial type of isomyosin is initially expressed in zones caudal and lateral to the areas of ventricular isomyosin expression. Medial to the atrial isomyosin-expressing areas, cardiogenic plate areas exist that initially lack myosin expression. Those parts of the cardiogenic plates that fuse in front of the anterior intestinal portal, thereby forming the heart tube, are characterized by the expression of both isomyosins; however, the caudolateral parts of the heart primordium maintain their single atrial isomyosin expression during further development. Cardiac contractions are therefore first observed at stage 10 (H/H, possessing ten pairs of somites) in myocardium that coexpresses both isomyosins.

8 Ill.

Electronic Resource