Oxygen transport from capillaries to exercising skeletal muscle is studied by use of a Krogh-type cylinder model. The goal is to predict oxygen consumption under conditions of high demand, on the basis of a consideration of transport processes occurring at the microvascular level. Effects of the decline in oxygen content of blood flowing along capillaries, intravascular resistance to oxygen dif...

Insulin transport across vascular endothelial cells is the rate limiting step in its time action profile. Glucose uptake in response to insulin is estimated through different techniques and is influenced by insulin sensitivity of the tissue. Glucose clamp technique and minimal model imply an incremental increase in the levels of insulin in the ISF compartment evidenced by increase in glucose up...

Most oxygen required to support the energy needs of vertebrate tissues is delivered by diffusion from microvessels. The presence of red blood cells (RBCs) makes blood flow in the microcirculation highly heterogeneous. Additionally, flow regulation mechanisms dynamically respond to changes in tissue energy demand. These spatiotemporal variations directly affect the supply of oxygen to parenchyma...

Permeability of brain capillaries of stroke-prone spontaneously hypertensive rats (SHRSP) was studied using labelling (horseradish peroxidase) and cytochemical techniques at the cellular level. In the cerebral capillary endothelium the tracer molecules were quickly transported by abundant transendothelial channels which directly connected the capillary lumen to the subendothelial space. Transen...

The transport and distribution of reaction products above catalytically active Pt microstructures was studied by spatially resolved scanning mass spectrometry (SMS) in combination with Monte Carlo simulation and fluid dynamics calculations, using the oxidation of CO as test reaction. The spatial gas distribution above the Pt fields was measured via a thin quartz capillary connected to a mass sp...

in this work a glass micromodel which its grains and pores are non-uniform in size, shape and distribution is considered as porous medium. a two-dimensional random network model of micromodel with non-uniform pores has been constructed. the non-uniformity of porous model is achieved by assigning parametric distribution functions to pores throat and pores length, which was measured using image a...

The current concept for high-level radioactive waste disposal at Yucca Mountain is for the waste to be placed in underground tunnels (or drifts) in the middle of a thick unsaturated zone. Flow modeling and field testing have shown that not all flow encountering a drift will seep into the drift. The underlying reason for the diversion of unsaturated flow around a drift is that capillary forces i...

The passage of materials across capillary walls is explained by passive physicochemical mechanisms in the classical physiological literature (1). More recently the participation of enzymes and structural alterations as a means of active transport has been extensively debated (2). Morphologic studies with the electron microscope have shown that the structure of capillary walls is different and m...

We report that the fast droplet transport without additional energy expenditure can be achieved on the spine of cactus (Gymnocalycium baldianum) with the assistance of its special surface structure: the cactus spine exhibits a cone-like structure covered with tilted scales. A single scale and the spine surface under it cooperatively construct a splayed capillary tube. The arrays of capillary tu...