Search results for " tension"

Size-Dependent Oxygenation and Energy Status in Multicellular Tumor Spheroids

1990

Multicellular tumor spheroids show numerous analogies to tumor microregions in vivo, such as the development of central necrosis at a certain spheroid size (for reviews see: Mueller-Klieser, 1987; Sutherland, 1988). The histological structure of the cell aggregates suggests that diffusion limitation of oxygen or nutrients in spheroids may cause cell death in the innermost parts of the spheroids. However, measurements with oxygen-sensitive microelectrodes are indicative of necrosis arising in the presence of relatively high oxygen tension (PO2) values, as they were found in normal tissue (Carlsson and Acker, 1985; Mueller-Klieser et al., 1986). Although still controversial in literature, rec…

Outcomes of a Teaching Learning Sequence on Modelling Surface Phenomena in Liquids

2023

In this paper we discuss the effects of modelling and computer simulation activities in promoting student use of lines of reasoning useful to explain proposed or observed situations. The activities are part of a structured Teaching/Learning Sequence on surface phenomena in liquids. We outline a model of liquid based on a mesoscopic approach, examples of computer simulations students can use during the activities, and we describe the Teaching/Learning Sequence. During the pedagogical activities, students can simulate the liquid behaviour by controlling many simulation parameters, such as the interaction intensity among liquid and solid particles. The results of the analysis of student answer…

Long-term results after thromboendarterectomy for chronic pulmonary embolism1

1999

Objective: In patients with chronic thromboembolic pulmonary hypertension, pulmonary vascular resistance (PVR) can be reduced by pulmonary thromboendarterectomy (PTE). In this study, long-term symptomatic and hemodynamic effects were investigated. Methods: Twenty-two patients (12 female, 10 male, mean age 40 years, preoperative NYHA functional class II/III/IV: n = 1/12/9) were re-evaluated 48‐72 months (mean 60 months) after surgery. In addition to clinical assessment, radiologic, hemodynamic and echocardiographic investigations were performed. Results: All patients reported a marked improvement of their clinical condition. At follow-up, 11 patients were identified as NYHA class I, 10 as NY…

STUDY REGARDING YARN TENSION DURING KNITTING ON CIRCULAR MACHINE WITH SMALL DIAMETER

2015

If yarn tension is controlled properly during knitting, it gives an improved and uniform fabric appearance. The main objective of knitters is to feed yarn to the knitting point at a low and uniform tension. To ensure that the stress do not affect yarn properties, literature recommends that the yarn tension shall be so adjusted that it fits in the field elastic. The value of the yarn stress influences not only quality of knitted product, but also the value of the knitting machine production, by the frequency rupture of yarns. This is influenced directly by the yarn stress and yarn quality. The value of this tension is influenced by a complex of factors, such as: technological diagram of the …

Stability of thin polymer films: influence of solvents.

2004

The interface and surface properties and the wetting behavior of polymer-solvent mixtures are investigated using Monte Carlo simulations and self-consistent field calculations. We carry out Monte Carlo simulations in the framework of a coarse-grained bead-spring model using short chains (oligomers) of N(P)=5 beads and a monomeric solvent, N(S)=1. The self-consistent field calculations are based on a simple phenomenological equation of state for compressible binary mixtures and we employ Gaussian chain model. The bulk behavior of the polymer-solvent mixture belongs to type III in the classification of van Konynenburg and Scott [Phil. Trans. R. Soc. London, Ser. A 298, 495 (1980)]. It is char…

The First Forty Years of a Technosol

2009

Abstract Soil formation is often a very slow process that requires thousands and even millions of years. Human influence, occasionally on a par with the function of climate or geological forces, can accelerate the process and can be viewed as a distinct soil forming factor. This paper describes a soil, Haplic Regosol, in which anthrosolization dominates the soil forming process. Man-made soils, Technosols, were stabilized with techniques of ecological engineering (crib walls). We measured the main soil properties and focused on the movement of water (the reduction of soil weight is the key factor in stabilizing these calcschists). The newly deposited debris, sheltered by anthropic intervent…

Analisi delle proprietà meccaniche di resine epossidiche invecchiate idro-termicamente

Il presente lavoro di tesi è stato prodotto sotto il patrocinio di una borsa di studio finanziata dal Ministero dell’Istruzione, dell’Università e della Ricerca (MIUR) nell’ambito del XXIX Ciclo di Dottorato di Ricerca in Ingegneria dell’Innovazione Tecnologica, attivo presso il Dipartimento dell’Innovazione Industriale e Digitale (DIID) dell’Università degli Studi di Palermo, Italia. Il lavoro propone uno studio del comportamento meccanico di resine termoindurenti sottoposte ad invecchiamento idro-termico. In particolare si prendono in considerazione resine epossidiche utilizzate in ambito strutturale: sia per la realizzazione di materiali compositi fibro-rinforzati a matrice polimerica (F…

La propagazione della frattura fragile nell'ambito della formulazione simmetrica del BEM

2009

Evidence for the Existence of an Effective Interfacial Tension between Miscible Fluids: Isobutyric Acid-Water and 1-Butanol-Water in a Spinning-Drop …

2006

We report definitive evidence for an effective interfacial tension between two types of miscible fluids using spinning-drop tensiometry (SDT). Isobutyric acid (IBA) and water have an upper critical solution temperature (UCST) of 26.3 degrees C. We created a drop of the IBA-rich phase in the water-rich phase below the UCST and then increased the temperature above it. Long after the fluids have reached thermal equilibrium, the drop persists. By plotting the inverse of the drop radius cubed (r(-)(3)) vs the rotation rate squared (omega(2)), we confirmed that an interfacial tension exists and estimated its value. The transition between the miscible fluids remained sharp instead of becoming more…

Microstructural modifications resulting from the dehydration of gypsum

2001

Various faces of dehydrated gypsum-cleaved blocks and single crystals have been investigated using optical microscopy, SEM, and TEM. The orientation of the cracks with respect to the initial gypsum structure and the Miller indices of all possible crack planes have been determined. These crack planes have been found to be few and to correspond to planes of high atomic density in the initial and final structures, therefore characterised by a low surface tension. These observations allow us to propose cracking criteria based on general concepts of crystal growth. The cracks' dimensions measured on different faces of the pseudomorph are distributed over several orders of magnitude and seems to …