Search results for " tension"
showing 10 items of 270 documents
Novel technologies to detect atelectotrauma in the injured lung
2010
ABSTRACTCyclical recruitment and derecruitment of lung parenchyma (R/D) remains a serious problem in ALI/ARDS patients, defined as atelectotrauma. Detection of cyclical R/D to titrate the optimal respiratory settings is of high clinical importance. Image-based technologies that are capable of detecting changes of lung ventilation within a respiratory cycle include dynamic computed tomography (dCT), synchrotron radiation computed tomography (SRCT), and electrical impedance tomography (EIT). Time-dependent intra-arterial oxygen tension monitoring represents an alternative approach to detect cyclical R/D, as cyclical R/D can result in oscillations of PaO2 within a respiratory cycle. Continuous…
Effect of Supplemental Oxygen versus Dobutamine Administration on Liver Oxygen Tension in dPP-Guided Normovolemic Pigs
2008
<i>Background:</i> Difference in pulse pressure (dPP) confirms adequate intravascular filling as a prerequisite for tissue perfusion. We hypothesized that both oxygen and dobutamine increase liver tissue oxygen tension (pt<i>O</i><sub>2</sub>). <i>Methods:</i> Eight anesthetized pigs received dPP-guided fluid management. Hepatic p<i>O</i><sub>2</sub> was measured with Clark-type electrodes placed subcapsularly, and on the liver surface. Pigs received: (1) supplemental oxygen (F<sub>i</sub><i>O</i><sub>2</sub> 1.0); (2) dobutamine 2.5 μg/kg/min, and (3) dobutamine 5 μg/kg/min. Data wer…
Pulmonary surfactant protein C containing lipid films at the air-water interface as a model for the surface of lung alveoli.
1995
The pulmonary surfactant lines as a complex monolayer of lipids and proteins the alveolar epithelial surface. The monolayer dynamically adapts the surface tension of this interface to the varying surface areas during inhalation and exhalation. Its presence in the alveoli is thus a prerequisite for a proper lung function. The lipid moiety represents about 90% of the surfactant and contains mainly dipalmitoylphosphatidylcholine (DPPC) and phosphatidylglycerol (PG). The surfactant proteins involved in the surface tension adaption are called SP-A, SP-B and SP-C. The aim of the present investigation is to analyse the properties of monolayer films made from pure SP-C and from mixtures of DPPC, DP…
Phase behaviour and interfacial tension of polysiloxane blends
1998
Abstract The cloud point curve for blends of poly(dimethyisiloxane) (PDMS, M w = 2.5kg mol −1 ) and poly(hexylmethylsiloxane) (PHMS, M w = 113kg mol − ] was determined turbidimetrically. The system demixes upon cooling and the UCST amounts to 36°C. The interfacial tension γ was determined at the critical composition for three temperatures by means of a spinning drop tensiometer. The dependence of γ on the reduced critical temperature can be described within experimental error by both the mean field theory and the Ising-3D theory.
Interfacial Assembly and Jamming Behavior of Polymeric Janus Particles at Liquid Interfaces
2017
The self-assembly and interfacial jamming of spherical Janus nanoparticles (JNPs) at the water/oil interface were investigated. Polymeric JNPs, made by cross-linking polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (PS-PB-PMMA), with a high interfacial activity assemble at the water/oil interface. During the self-assembly at the interface, the interfacial energy was reduced and a dynamic interlayer was observed that is responsive to the pH of the aqueous phase. Unlike hard particles, the JNPs are composed of polymer chains that can spread at the liquid-liquid interface to maximize coverage at relatively low areal densities. In a pendant drop geometry, the interfacial area of …
Interfacial energy effects within the framework of strain gradient plasticity
2009
AbstractIn the framework of strain gradient plasticity, a solid body with boundary surface playing the role of a dissipative boundary layer endowed with surface tension and surface energy, is addressed. Using the so-called residual-based gradient plasticity theory, the state equations and the higher order boundary conditions are derived quite naturally for both the bulk material and the boundary layer. A phenomenological constitutive model is envisioned, in which the bulk material and the boundary layer obey (rate independent associative) coupled plasticity evolution laws, with kinematic hardening laws of differential nature for the bulk material, but of nondifferential nature for the layer…
Analysis of Autoantibodies Against Human Retinal Antigens in Sera of Patients with Glaucoma and Ocular Hypertension
2008
The aim of this study was to show that complex antibody patterns against retinal antigens in sera of patients with glaucoma, found in previous studies, are autoantibodies against human antigens.Sera of 179 patients were collected at the Department of Ophthalmology (University of Mainz, Germany): non-glaucomatous control patients (n=45), primary open-angle glaucoma (n=45), ocular hypertension (n=44), and normal tension glaucoma patients (n=45). The sera were tested against Western blots of human retinal antigens. IgG antibody patterns were analyzed by multivariate statistical techniques, and some significant antigens were identified by mass spectrometry.All subjects, even healthy ones, showe…
ANALISI DELLE TENSIONI RESIDUE NEI VETRI MEDIANTE FOTOELASTICITÀ RGB E LASTRA A TINTA SENSIBILE
2012
L'analisi delle tensioni residue nel vetro viene solitamente effettuata mediante metodi fotoelastici. Questo lavoro considera l'automazione del metodo fotoelastico in luce bianca basato sull'uso congiunto della fotoelasticità RGB e di una lastra a tinta sensibile (full wave plate o tint plate), che manifesta il ritardo di un ordine di frangia, posta in serie alla lastra di vetro. Il metodo proposto è stato applicato all’analisi delle tensioni residue membranali in un vetro temperato.
Prognostic Potential Of The Pretherapeutic Tumor Oxygenation Status
2009
Hypoxia, a characteristic feature of locally advanced solid tumors, has emerged as a key factor of the tumor pathophysiome, since it can promote tumor progression and resistance to therapy. Independent of established prognostic parameters, such as clinical tumor stage, histology, histological grade and nodal status, hypoxia has been identified as an adverse prognostic factor for patient outcome. Studies of pretreatment tumor hypoxia involving direct assessment (polarographic oxygen tension measurements) have suggested a poor prognosis for patients with hypoxic tumors. These investigations indicate a worse disease-free survival for patients with hypoxic cancers of the uterine cervix or soft …
Effects of KL4-Type Peptides on the Surface Activity and Stability of Pulmonary Surfactant Films as Evaluated in the Captive Bubble Surfactometer
2012
Although SP-B is the most critical protein in lung surfactant, recombinant or synthetic forms of SP-B as a basis for the development of therapeutic surfactants are still not available. An alternative is the design and production of peptides mimicking the structure and general properties of essential motifs in SP-B.In the present study the surface activity of different KL4-derived peptides, as sequence variations of the original peptide designed to replicate a general amphipathic motif of SP-B [1], has been assessed in the captive bubble surfactometer. The peptides were reconstituted in a surfactant lipid matrix: DPPC/POPC/POPG (50:25:15, w/w/w). This mixture was selected because it offers a…