Flow and pattern formation in a binary mixture of rotating granular materials

In a horizontally rotating cylinder, size segregation, pattern formation, and its time development are studied for a binary mixture of rodlike and disklike materials at various rotational frequencies. The rodlike particles formed a network that influenced their mobility and the shape of the avalanching surface. Windows installed on the cylinder enabled us to examine and control the distribution of the components of the mixture throughout the bulk. This has allowed us to study the evolution of naturally occurring and artificially created patterns. All observed patterns had a degree of asymmetry and were unstable. The stability of a band pattern is shown to depend on its symmetry. Qualitatively, the time for the transition from one set of bands to another was inversely related to the degree of asymmetry of the pattern. In addition, we propose that the parameter D/d (diameter of the cylinder over the diameter of the grains) plays a significant role in the functional dependence of the avalanching surface current on the dynamical angle of repose, and in the segregation process itself.

The effect of isovolaemic haemodilution on infection-related serum protein levels.

Approximately 25% of blood was replaced by either hydroxyethyl starch (mol. wt 450,000), dextran (mol. wt 60,000), or 5% plasma protein solution, 24 h prior to a surgical intervention. Twenty-four adult patients were studied and haematocrit, total protein, plasma albumin, alpha-1-antitrypsin, IgG, IgM, antithrombin III, fibronectin and alpha-2-macroglobulin were determined. The resulting blood concentrations suggest that the various replacement solutions exert only a dilutional effect upon the proteins studied. Furthermore, there is no difference regarding the course of the various infection-related proteins whether plasma protein solution or synthetic colloids are used for blood replacement. The decrease of the studied proteins during the study period does not exceed 35% of the control value. This is not considered to be a clinically significant reduction and levels of infection-related proteins were not dangerously low.

[Does gelatin as a blood substitute selectively depress plasma fibronectin? A clinical randomized study]. / Senkt Gelatine als Blutersatzmittel selektiv das Plasmafibronectin? Eine klinische randomisierte Studie.

In 18 adult patients, in a randomized way, 15 ml/kg of blood were replaced either by gelatin 5.5 pc or serum protein solution. 0,5, 4 and 24 h later there was only a significant difference between the two groups in total protein and serum albumin. The low molecular weight infection related proteins alpha-1-antitrypsin, immunoglobulin G and antithrombin III, as well as the high molecular weight proteins immunoglobulin M, plasma fibronectin and alpha-2-macroglobulin were at no time significantly different between the two groups. It is concluded that gelatin as a plasma substitute does not impair the opsonising effect of plasma fibronectin upon the reticuloendothelial system.

[Behavior of renal filtration performance in the massive intraoperative administration of crystalloid solutions]. / Das Verhalten der renalen Filtrationsleistung bei grosszügiger intraoperativer Zufuhr von kristalloiden Lösungen.

Renal function of 12 adult patients was studied pre- and postoperatively using tracer techniques in a black-box model. Chrom 51 EDTA was employed to determine extracellular fluid volume and glomerular filtration rate, Iodine 125-albumin to measure plasma volume. These patients who received during two 4-h periods pre- and postoperatively 3 ml/kg/h of a salt-sugar solution had a significantly increased extracellular fluid volume postoperatively. Glomerular filtration rate was also increased, plasma volume was significantly reduced and colloidosmotic pressure in spite of attempts to supplement albumin solution intraoperatively was found to be postoperatively reduced. Hemodynamic parameters were virtually unchanged postoperatively with the exception of a small but significant increase of cardiac index. It is concluded, that these patients who received 12 ml/kg/h of crystalloid solutions apart from colloid replacement of measured bloodloss intraoperatively through natural regulation were about to excrete this extra amount of fluid, which had been relocated in the extracellular space. This regime, however, might help to decrease the rate of oliguric perioperative renal function failure, which has a high mortality.

[Effect of hemodilution with plasma protein solution and hydroxyethyl starch on plasma fibronectin]. / Der Einfluss von Hämodilution mit Plasmaproteinlösung und Hydroxyäthylstärke auf das Plasmafibronectin.

In nine adult patients at least 24 hours prior to vascular surgical operations about 25 p.c. of circulating blood volume was replaced by either 6 p.c. hydroxyethyl starch (HES) or 5 p.c. plasmaprotein solution (PPS). Following haemodilution, a proportional significant decrease of plasmafibronectin (PFN) was observed; when PPS was administered, levels were significantly higher than expected due to withdrawal of blood. Serumalbumin was decreased in the same way, however, in patients receiving HES it rose significantly within 24 hours. It is concluded that changes are essentially only dilutional and when haemodilution technique is used, also postoperatively no dramatic reduction of PFN following uncomplicated surgery has to be anticipated.

Lymphocyte transformation and isovolemic hemodilution with hydroxyethylstarch 450,000.

The effect of hemodilution upon lymphocyte transformation was studied in vivo. 20 p.c. of circulating blood volume was replaced by Hydroxyethylstarch 450,000 6%, (HES 450) and 24 hours later but prior to surgery lymphocyte transformation using PHA was not substantially changed. These findings were in accord with previous in vitro studies. There appeared to be no significant change of the total lymphocyte count, alteration of serum proteins seemed to be proportional presenting a mere dilutional phenomenon. It can thus be concluded that hemodilution does not impair cellular immune defense nor increase the risk for patients prone to sepsis or spread of malignancy.

[Arterial baroreflex in intravenous anesthesia and assisted spontaneous respiration]. / Arterieller Baroreflex bei intravenöser Narkose und assistierter Spontanatmung.

Effects of a combined intravenous anaesthesia on the baroreceptor control of the circulation were determined in 8 healthy, unpremedicated patients, 18-50 years of age, scheduled for minor surgical procedures. The baroreflex was studied in response to brief hypotension with nitroglycerin (1-10 micrograms/kg i.v.) and quantified using the method described by Smyth, Sleight and Pickering (1969). The latter linearly correlates measurements of systolic blood pressure and the succeeding pulse interval, as obtained from recordings of the electrocardiogram. Responses in the conscious state were compared with those after administering diazepam (0.2 mg/kg i.v.), etomidate (8-20 mg i.v.) and fentanyl (0.015-0.025 mg/kg i.v.) while the patients were breathing a mixture of oxygen and nitrous oxide (1:2) during mechanically assisted ventilation. Anaesthesia led to a decrease in heart rate (17 +/- 3%) together with a slight but significant reduction in mean arterial pressure (15 +/- 4%). The mean slopes and correlation coefficients in the conscious and anaesthetized states were y = 426 + 2.33 X; r = 0.56; p less than 0.05 and y = 663 + 2.16 X; r = 0.49; p less than 0.05, respectively. Thus, no significant difference of the function of the baroreflex was observed in the conscious and anaesthetized patients. It is concluded that in contrast to inhalational anaesthesia the employed combined intravenous anaesthesia with mechanically assisted ventilation does not change this important control mechanism of the circulation in man.

[Hemoconcentration caused by excessive intraoperative ascites production in ulcer bleeding]. / Hämokonzentration durch intraoperative exzessive Aszitesproduktion bei Ulkusblutung.

The estimation of the intraoperative fluid requirements can be particularly difficult in patients with compartmental disturbances, e.g. hepatic cirrhosis. The case history of a 41 year old female with a known history of liver cirrhosis is reported who underwent emergency surgery due to upper gastro-intestinal bleeding. In order to maintain hemodynamic stability preoperative blood loss was replaced with fresh blood. During the operation 4 liters of bank and fresh blood with 5 liters of erythrocyte-free fluids were administered. After operation reliable clinical signs of hypovolemia and a marked increase in hematocrit were noted. The severe hemoconcentration was explained by excessive fluid shifts away from the intravascular compartment since a total amount of 10 liters of ascites was collected for the next 24 hours. This overproduction can be related to portal hypertension, hypoalbuminemia and activation of the renin-angiotensin-aldosterone system.

[Effect of dextran 60,000(D 60) and hydroxyethyl starch 450,000 (HES 450) on lymphocyte transformation]. / Der Einfluss von Dextran 60 000 (D 60) und Hydroxyäthylstärke 450 000 (HAS 450) auf die Lymphozytentransformation.

Lymphocytes of volunteers were recovered, isolated and H3 thymidine incorporation was measured in the presence of D 60 and HES 450 with and without PHA. Without mitogen dextran caused only a marginal increase of incorporation whereas HES brought about no change. When PHA-stimulation was used, both compounds seemed not to influence H3-thymidine incorporation. It is concluded that in vitro even in molar concentrations corresponding to clinical haemodilution these solutions appear not to suppress lymphocytic activity.