Applicability of an entry flow model of the brachial artery for flow models of the hemodialysis fistula.

The native arteriovenous fistula creates a shunt that provides the high blood flow that is needed for dialysis. Lumped parameter hemodynamic models of the arteriovenous fistula can be used to predict shear stresses and pressure losses and can be applied to help understand unsolved problems such as the high rate of arteriovenous fistula maturation failure. These models combine together flow components, such as arteries, stenosis, anastomoses, arterial compliance, and blood inertia, and each component must be modeled with an appropriate pressure-flow relationship.

Gas-phase detection of solid-state fission product complexes for post-detonation nuclear forensic analysis.

This study presents the first known detection of fission products commonly found in post-detonation nuclear debris samples using solid sample introduction and a uniquely coupled gas chromatography inductively-coupled plasma time-of-flight mass spectrometer. Rare earth oxides were chemically altered to incorporate a ligand that enhances the volatility of the samples. These samples were injected (as solids) into the aforementioned instrument and detected for the first time.

A novel dynamic layer-by-layer assembled nano-scale biointerface: functionality tests with platelet adhesion and aggregate morphology influenced by adenosine diphosphate.

An improved biointerface was developed, dynamic layer-by-layer self-assembly surface (d-LbL), and utilized as a biologically-active substrate for platelet adhesion and aggregation. Possible clinical applications for this research include improved anti-coagulation surfaces. This work demonstrated the functionality of d-LbL biointerfaces in the presence of platelet-rich-plasma (PRP) with the addition of 20 μM adenosine diphosphate (ADP), a thrombus activator.

In vitro verification of multiple-receiver Doppler ultrasound for velocity estimation improvement.

The coherent scattering effect, which introduces noise in Doppler-derived velocity estimates, is caused by constructive and destructive interference of sound waves scattered from multiple particles. Because the phase relationship between signals scattered from different particles depends on the orientation of the receiver, the error in a given velocity estimate depends on the receiver location. To examine this dependence, the velocity of a steady uniform flow was measured simultaneously with a transceiver and three receivers, and the cross-correlation coefficients between velocity estimates for pairs of crystals were calculated.

Basic optics of effect materials.

Effect materials derive their color and effect primarily from thin-film interference. Effect materials have evolved over the decades from simple guanine crystals to the complex multilayer optical structures of today. The development of new complex effect materials requires an understanding of the optics of effect materials.

Inflow stenosis obscures recognition of outflow stenosis by dialysis venous pressure: analysis by a mathematical model.

Background: Recent studies have shown that inflow stenosis of haemodialysis grafts is more common than previously realized. The influence of inflow stenosis on graft haemodynamics and venous pressure (VP) surveillance has not been previously systematically studied.

Methods: We used a well-established mathematical model to determine the relation between inflow stenosis and static VP (adjusted for mean arterial pressure, VP/MAP), outflow stenosis and artery and vein luminal diameters.

Mathematical model for pressure losses in the hemodialysis graft vascular circuit.

Stenosis-induced thrombosis and abandonment of the hemodialysis synthetic graft is an important cause of morbidity and mortality. The graft vascular circuit is a unique low-resistance shunt that has not yet been systematically evaluated. In this study, we developed a mathematical model of this circuit.

In vivo validation of glucose pump test for measurement of hemodialysis access flow.

Background: The glucose pump test (GPT) is a recently introduced method of measuring hemodialysis access blood flow (Qa). A validation of GPT during dialysis has not yet been done, and performance characteristics of the method have not yet been fully analyzed.

Methods: The authors studied 33 patients (25 synthetic grafts, 8 autogenous arteriovenous fistulae).

Biocompatibility of layer-by-layer self-assembled nanofilm on silicone rubber for neurons.

Electrostatic layer-by-layer (LbL) self-assembly, a novel method for ultrathin film coating has been applied to silicone rubber to encourage nerve cell adhesion. The surfaces studied consisted of precursor layers, with alternating cationic poly(ethyleneimine) (PEI) and anionic sodium poly(styrenesulfonate) (PSS) followed by alternating laminin and poly-D-lysine (PDL) layers or fibronectin and PDL layers. Film growth increased linearly with the number of layers.

Biomedical applications of electrostatic layer-by-layer nano-assembly of polymers, enzymes, and nanoparticles.

The introduction of electrostatic layer-by-layer (LbL) self-assembly has shown broad biomedical applications in thin film coating, micropatterning, nanobioreactors, artificial cells, and drug delivery systems. Multiple assembly polyelectrolytes and proteins are based on electrostatic interaction between oppositely charged layers. The film architecture is precisely designed and can be controlled to 1-nm precision with a range from 5 to 1000 nm.

Coating and selective deposition of nanofilm on silicone rubber for cell adhesion and growth.

A recently developed method for surface modification, layer-by-layer (LbL) assembly, has been applied to silicone, and its ability to encourage endothelial cell growth and control cell growth patterns has been examined. The surfaces studied consisted of a precursor, with alternating cationic polyethyleneimine (PEI) and anionic sodium polystyrene sulfonate (PSS) layers followed by alternating gelatin and poly-D-lysine (PDL) layers. Film growth increased linearly with the number of layers.

Gelatin-glutaraldehyde cross-linking on silicone rubber to increase endothelial cell adhesion and growth.

Silicone is a biomaterial that is widely used in many areas because of its high optical clarity, its durability, and the ease with which it can be cast. However, these advantages are counterbalanced by strong hydrophobicity. Gelatin cross-linking has been used as a hydrophilic coating on many biomaterials but not on silicone rubber.

Nano-encapsulation of furosemide microcrystals for controlled drug release.

Furosemide microcrystals were encapsulated with polyions and gelatin to control the release of the drug in aqueous solutions. Charged linear polyions and gelatin were alternatively deposited on 5-microm drug microcrystals through layer-by-layer (LbL) assembly. Sequential layers of poly(dimethyldiallyl ammonium chloride) (PDDA) and poly(styrenesulfonate) (PSS) were followed by adsorption of two to six gelatin/PSS bilayers with corresponding capsule wall thicknesses ranging from 45 to 115 nm.

Reduction of coherent scattering noise with multiple receiver Doppler.

Doppler ultrasound (US) velocity estimates are inherently subject to error as a result of both Doppler ambiguity and coherent scattering. The coherent scattering error is a result of changes in the phase of the returned echo as particles enter and leave the sample volume. This phase depends on the distance from the transmitter to the scatterer and then to the receiver.

Electrostatic layer-by-layer nanoassembly on biological microtemplates: platelets.

Platelets were coated with 78-nm silica nanoparticles, 45-nm fluorescent nanospheres, or bovine immunoglobulin G (IgG) through layer-by-layer assembly by alternate adsorption with oppositely charged linear polyions. Sequential deposition on platelet surfaces of cationic poly(dimethyldiallylammonium chloride) and anionic poly(styrene sulfonate) was followed by adsorption of nanoparticles or immunoglobulins. Nano-organized shells of platelets were demonstrated by transmission electron microscopy and fluorescence microscope images.