Search results for "meniscu"
showing 10 items of 30 documents
Real-time microfluorescence studies of Langmuir-Blodgett deposition: Monolayer adsorption and desorption
1990
Abstract Observations of the meniscus region in a typical Langmuir-Blodgett configuration are obtained using fluorescence microscopy. Studies of the meniscus position as a function of pH demonstrate that the meniscus height increases upon charging the monolayer owing to the repulsive interaction between monolayer and substrate surfaces. Through the correspondence between meniscus height and contact angle the adhesion forces between monolayer and substrate as a function of monolayer charge are assessed. The phenomenon of desorption upon resubmerging a deposited film is described and it is shown that the meniscus height at the onset of the desorption is greater for higher pH.
Studies of monolayer/substrate adhesion as function of the monolayer headgroup charge: DMPE and DMPA
1991
The variation of the work of adhesion between lipid monolayers and a plane silicon oxide surface in a typical LB-configuration is measured as function of the subphase pH. The adhesion energy is deduced via fluorescence microscopy from the equilibrium meniscus height. With increasing pH the negative headgroup charge of both, dimyristoylphosphatidylethanolamine (DMPE) and dimyristoylphosphatidic acid (DMPA) monolayers increases. The increasing charge of DMPE is reflected in a measured decrease of the work of adhesion at higher pH. The DMPA/SiO2 interaction is not affected by increasing headgroup charges. These results are qualitatively understood in terms of an electrostatic double layer inte…
Physisorption Instabilities during Dynamic Langmuir Wetting
1994
Continuous dynamic Langmuir wetting of lipid monolayers can create regular stripe patterns on the solid substrate surface. Monolayers doped with minor amounts of fluorescence dye may be deposited in stripes of alternating high and low dye concentration. In case of pure monolayers stripes are observed with AFM. The striations run normal to the dipping direction and have widths of typically several micrometres and distances varying from 1 to ≈ 100 μm. The stripe widths, distances, and fluorescence contrast depend on deposition speed, surface pressure, substrate surface preparation, and dye concentration. The patterns probably result from physisorption (meniscus) instabilities caused by a feed…
MRT des Kniegelenkes: Fehleranalyse bezüglich der Meniskus- und Kreuzbanddiagnostik an einem arthroskopisch kontrollierten Patientenkollektiv
1998
PURPOSE To categorise discrepancies in findings of the menisci and anterior cruciate ligament (ACL) between arthroscopy and MRI. MATERIALS AND METHODS The MRIs of 236 patients were retrospectively analysed by an experienced radiologist without knowledge of clinical and/or operative findings. Discrepancies in arthroscopic findings were reevaluated together with the arthroscopist to determine their cause of error. RESULTS The diagnostic accuracies for injuries of the medial and lateral meniscus and the ACL were 92.4%, 92.4%, and 94.1%, respectively. For the menisci, causes for discrepancies in findings (n = 31) were: overinterpretation of central signal intensities with contact to the menisca…
Niederfeld-MR-Tomographie des Kniegelenkes: Ergebnisse einer prospektiven, arthroskopisch kontrollierten Studie
2008
PURPOSE To define the diagnostic accuracy of an open low-field MR unit (Magnetom Open, Siemens, Erlangen) in traumatic knee lesions. MATERIALS AND METHODS The MRIs of 150 patients were prospectively evaluated by two independent readers with different experience levels. The study protocol included a proton-density weighted SE-sequence in the sagittal, a T2.-weighted Flash-2D-sequence in the coronal, and a 3D-acquisition (DESS) in the axial plane. 75 patients were treated either conservatively or operatively. RESULTS Based on arthroscopy as the gold standard, the sensitivities, specificities, and diagnostic accuracies for lesions of the medial and lateral meniscus, the anterior cruciate ligam…
Impact of contact lens material and design on the ocular surface.
2018
BACKGROUND: To evaluate the impact on the ocular surface of a daily disposable hydrogel contact lens with high water content compared with two silicone hydrogel daily disposable lenses of lower water content. METHODS: The hydrogel lens assessed was made from nesofilcon A and the silicone hydrogel lenses were made of delefilcon A and stenfilcon A. Contact lens thickness was measured to assess material stability during daily wear, and ocular surface parameters such as tear film osmolarity, tear meniscus area and central corneal thickness were also assessed. Optical quality was analysed for all cases by means of wavefront aberrometry. RESULTS: The nesofilcon A was shown to be the thinnest lens…
Comparison of two artificial tear formulations for dry eye through high‐resolution optical coherence tomography
2011
Purpose: The aim was to determine the efficacy of two artificial eye-drop formulations by analysing the lower tear film meniscus volume through a commercial high-resolution spectral-domain optical coherence tomographer. Methods: Twenty dry eye patients (12 men, eight women, aged 57.5 ± 8.4 years) with refractive errors from -2.50 to +0.75 D (mean -1.34 ± 1.02 D) and cylinders lower than 1.00 D were examined. Tear meniscus volume was measured before, immediately after and 10, 30 and 60 minutes after instillation using the Copernicus high-resolution spectral-domain optical coherence tomographer (Optopol Tech SA, Zawiercie, Poland). Volume was calculated from the local area obtained from tom…
Comparison of the influence of corneo-scleral and scleral lenses on ocular surface and tear film metrics in a presbyopic population
2018
PURPOSE: To assess and compare the effect of the corneo-scleral lenses (C-ScL) and scleral lenses (ScL) on tear film parameters and central corneal thickness (CCT) in healthy presbyopic subjects. METHODS: Thirty subjects wore two contact lenses (CLs), randomly assigned, of neutral power, but of different diameters, 12.7mm (C-ScL) and 18mm (ScL) and being equal in the others parameters: material (HS100) and centre thickness (0.29mm). At baseline, 20min after insertion and at 8h, the tear meniscus area (TMA) and CCT was measured (with optical coherence tomography) as well as tear osmolarity. RESULTS: TMA revealed statistical differences for both lenses at 20min (p<0.001), and also at 8h (p=0.…
Isotropic-nematic interface and wetting in suspensions of colloidal platelets.
2006
We study interfacial phenomena in a colloidal dispersion of sterically stabilized gibbsite platelets, exhibiting coexisting isotropic and nematic phases separated by a sharp horizontal interface. The nematic phase wets a vertical glass wall and polarized light micrographs reveal homeotropic surface anchoring both at the free isotropic-nematic interface and at the wall. On the basis of complete wetting of the wall by the nematic phase, as found in our density functional calculations and computer simulations, we analyze the balance between Frank elasticity and surface anchoring near the contact line. Because of weak surface anchoring, the director field in the capillary rise region is uniform…
Meniscus coated high open-circuit voltage bi-layer solar cells
2012
Neat bi-layer solar cells of a fullerene acceptor and a cyanine dye donor were prepared using meniscus coating. Meniscus coating is very material efficient and leads to high quality pinhole-free films. The cells exhibit high open circuit voltages of 1 volt, only 0.8 eV below the band gap of the cyanine dye. This is one of the smallest differences reported for organic solar cells and illustrates an almost optimal donor-acceptor energy level alignment.