Quantitative modeling of the physiology of ascites in portal hypertension

Although the factors involved in cirrhotic ascites have been studied for a century, a number of observations are not understood, including the action of diuretics in the treatment of ascites and the ability of the plasma-ascitic albumin gradient to diagnose portal hypertension. This communication presents an explanation of ascites based solely on pathophysiological alterations within the peritoneal cavity. A quantitative model is described based on experimental vascular and intraperitoneal pressures, lymph flow, and peritoneal space compliance. The model's predictions accurately mimic clinical observations in ascites, including the magnitude and time course of changes observed following paracentesis or diuretic therapy

The Membrane Properties of Electroactive Polymer Films

Electroactive polymers fall into two categories. The first group are the redox polymers, which consist of an electronically insulating polymer matrix with attached redox sites.(1–4) The PVPy/Ru matrix represented in Fig. 3.1 is a typical example. The second group are the conjugated polymers, such as polypyrrole, polyaniline, or the poly(Nsulfopropylpyrrole-co-pyrrole) represented in Fig. 3.2. These consist of extended π-electron systems from which electrons can be withdrawn (see Fig. 3.2) or into which additional electrons can be injected.(5–12) The unpaired electrons of the produced radical cations or anions are delocalized over several monomer units of the polymer chain, forming polarons that interact with one another. With increasing concentration they associate to form bipolarons, i.e., electronspin-free dimers.(13)</sup