Does the subdural space exist?

A potential space between the dura mater and the arachnoides is thought to exist, occupied by a serous fluid and called the subdural space. Recent studies may change this classical concept, however. The dura-arachnoid complex from the epidural to the arachnoid space is formed by morphologically distinct layers: the dura mater, the subdural compartment and the arachnoid mater, which are made up of different cell types. The dura mater consists of greater and lesser laminae formed mainly of collagen fibers aligned differently. The subdural compartment is formed by a number of so-called "neurothelial cells", which are in close contact with the inner dural layers. These cells are flat and have long interlaced branches. The arachnoides are made of cells grouped in three different layers. The outer layer is the "barrier arachnoid layer". Located just inside the anterior cell plane, this layer is made of less flattened cells that form an epithelial-type tissue, with complex cell-cell junctures surrounded by collagen fibers. The middle layer is the reticular arachnoid, composed of irregularly interlaced cells alternating with collagen fibers and intercellular gaps of varying sizes. The innermost layer, the trabecular arachnoid, is in direct contact with the subarachnoid space. The cells of this layer form strands that contribute to the weblike pattern found in the subarachnoid space. Recently, special techniques for fixing and preparing samples, preserving in situ the anatomical relations between the arachnoides and the dura mater, have allowed us to examine the normal configuration of the subdural space. All samples examined revealed the presence of a cellular plane between the dura mater and the arachnoides, with no evidence of the classically described space. The zone of least resistance in the dura-arachnoid complex was the subdural compartment, which could be torn mainly along intercellular spaces, though cell rupture was also observed, affecting the cytoplasmic membranes of adjacent cells. The subdural space is opened by tearing the subdural compartment between neurothelial cells alongside the collagen fibers of the dura mater. Such a tear can be caused mechanically by injecting air or contrast media, which exert pressure on a laminar structure that tends to separate because it is weaker than neighboring ones.     

In Vitro and In Vivo Behaviour of In Complexes of TTHA, TTHA-Bis(Butylamide) and TTHA-Bis(Glucamide): Stability, Biodistribution and Excretion Studied by Gamma Imaging

Aiming at radiopharmaceutical application, (111)In(3+) complexes of the polyaminocarboxylates TTHA, TTHA-bis(butylamide) and TTHA-bis(glucamide) were investigated. The in vitro stability of (111)In(TTHA)(3-) and (111)In(TTHA-bis(butylamide)(-) was evaluated by measuring the exchange of (111)In(3+) from the complexes to transferrin and the results were compared with those for (111)In(DTPA)(2-). We also performed biodistribution studies of the three (111)In(3+) complexes by gamma-imaging in Wistar rats and by measuring the radioactivity in their organs. TTHA and its derivatives seem to have similar in vivo biodistribution with prevailing renal excretion.     

Production of perovskite-like La1−xCaxMnO3+δ ferromagnetic thin films by electrochemical reduction

Ferromagnetic and perovskite-like thin films (<1m) of La1–xCaxMnO3+ have been routinely prepared by heat treatment of an amorphous La–Ca–Mn precursor. The precursor was electrodeposited cathodically in the absence of oxygen and water onto polished silver substrates from a nonaqueous solution of the components' nitrates. Analysis by X-ray diffraction and SQUID magnetometry shows these materials exhibit the appropriate structural and magnetic phases indicative of colossal magnetoresistance.     

Composite transducers for amperometric biosensors. The glucose sensor

A new concept of a composite transducer for amperometric biosensors based on the use of a solid substance with amphiphilic character (called a solid binding matrix, SBM) is presented. The electrochemical properties of the transducers prepared with five different SBMs and the characteristics and performance of SBM-based glucose sensors prepared by three different methods are described. Biosensor stability is evaluated and discussed. The biosensor was used for the determination of glucose in wine, yielding results which were consistent with those obtained with the commercially available Glucose Enzyme Photometric Kit. The average accuracy was 6% for the whole range of analyzed concentrations (0.2-47 g/L) using the same sample dilution in a buffer.     

Automatic analysis of speckle photography fringes

Speckle interferometry is a technique adequate to metrological problems such as the measurement of object deformation. An automatic system of analysis of such measurements is given; it consists of a motorized x-y plate positioner controlled by computer, a CCD video camera, and software for image analysis. A fringe-recognition algorithm determines the spacing and orientation of the fringes and permits the calculation of the magnitude and direction of the displacement of the analyzed object point in images with variable degrees of illumination. For a 256 x 256 pixel image resolution, the procedure allows one to analyze from three fringes to a number of fringes that corresponds to 3 pixels/fringe.     

Automated stabilization of a single-pass plane Fabry-Perot interferometer

We describe a home-built data-acquisition and stabilization system designed for small-angle Brillouin experiments. The stabilization system exhibits good performance, as supported by the obtained experimental spectra. Collected data for the sound velocity of benzene and isopropyl alcohol against sample temperature are compatible with existing results.     

Modeling (2-2) piezocomposites partially sliced in the polymer phase

Different attempts have been suggested to improve the efficiency of piezocomposites. Here, a new design which consists of subdicing the passive part of (2-2) composites is presented. A theoretical model based on the series-parallel connections of elastic sections has been developed. It is shown that the cuts increase the electromechanical coupling coefficient. The model shows that, at high ceramic percent, the resonance frequency decreases when cutting the composite. At low ceramic percent the behavior is the opposite. Samples of (2-2) piezocomposites with low, medium, and high ceramic percent have been made, comparing predictions with experimental results. The agreement is satisfactory. With this composite structure, another design parameter is added to the search for better piezocomposite performance.     

XPS characterization of surface films formed on surface-modified implant materials after cell culture

Nitrogen ion-implanted Ti–6Al–4V, Ti–5Al–2.5Fe and 316 L stainless steel and nitrogen or carbon sputter-coated samples were inoculated with rat bone marrow. The interface between the cell layer and the substrata was studied by X-ray photo-electron spectrometry and observed by scanning electron microscopy (SEM). Ca and P were detected on all materials after in vitro cell culture. Titanium appears to be present mainly in the form of TiO2.