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PubMedDate not supplied

Cerebral blood flow is regulated by changes in blood pressure and in blood viscosity alike.

There is still considerable controversy regarding the influence of blood viscosity upon CBF. We have measured CBF with microspheres in 23 cats. Autoregulation was disturbed in the left caudate nucleus by microsurgical occlusion of the left middle cerebral artery. Induced hypertension or hypotension was used and i.v. mannitol (1 g/kg) administered. In all cats blood viscosity decreased an average of 16% at 15 minutes and, in 16 cats, increased 10% at 75 minutes post-mannitol. CBF in the right caudate was 79 +/- 6 ml/100g/min, in the left 38 +/- 6 (p less than 0.001). Only minor changes of CBF occurred in areas with presumed normal autoregulation, including the right caudate, in conjunction with pressure or viscosity changes. In the left caudate CBF decreased 21% with hypotension and 18% with higher viscosity, more than on the right (p less than 0.01 and p less than 0.2, respectively). CBF increased in the left caudate 56% with hypertension and 47% with lower viscosity, again much more than on the right (p less than 0.001 and p less than 0.01, respectively). In the other area which is (nearly) exclusively supplied by the middle cerebral artery of the cat, i.e., the ectosylvian cortex, results were similar to those in the caudate nucleus. These results show that viscosity changes must result in compensatory readjustments of vessel diameter, but that these adjustments do not occur where autoregulation to pressure changes is known to be defective. The adjustments to viscosity changes might be called blood viscosity autoregulation of CBF. We hypothesize that pressure autoregulation and blood viscosity autoregulation share the same mechanism.

Animals↗
PubMed1974

Disturbance of serum viscosity in diabetes mellitus.

The serum viscosity of diabetic patients has been found to be increased. The elevation averaged 8% above healthy subjects and 6% above nondiabetic patients. The serum viscosity elevation was greater when diabetic sequelae associated with microangiopathy were present. No relation of serum viscosity to age, sex, obesity, duration of disease, or type of treatment was demonstrated. Serum total protein and glucose levels were found to be correlated with serum viscosity, and increases in their serum concentrations were observed in diabetes. Analysis demonstrated that their elevation did not explain either the viscosity increase or the difference in viscosity between diabetics with and without sequelae.Intrinsic viscosity, abbreviated [eta], is a concentration-independent solute property related to molecular shape. [eta] was found to be 7% higher in diabetic than in normal serum. The [eta] difference accounted for at least half of the serum viscosity elevation. The rest of the increase was due to increased serum protein level and increased nonprotein solids, presumably glucose and lipid. Associated with increased [eta] was a decline in albumin: globulin ratio and elevation of the acute phase reactant proteins, alpha(1)-acid glycoprotein, alpha(1)-antitrypsin, haptoglobin, and ceruloplasmin. Studies comparing diabetic and normal serum fractionated by using 21.5% sodium sulfate showed that changes in [eta] were attributable to changes in serum protein composition rather than an inherent qualitative disturbance of protein present in one of the fractions. Since serum viscosity is elevated in early diabetes, it may be a part of the metabolic disturbance of diabetes and could play a role in the development of diabetic microangiopathy.

Adult↗
PubMed1993

Increased plasma viscosity as a reason for inappropriate erythropoietin formation.

The aim of this study was to examine whether altered plasma viscosity could contribute to the inappropriately low production rate of erythropoietin (EPO) observed in patients suffering from hypergammaglobulinemias associated with multiple myeloma or Waldenström's disease. We found that the EPO formation in response to anemia in these patients was inversely related to plasma viscosity. A similar inverse relationship between plasma viscosity and EPO production was seen in rats in which EPO formation had been stimulated by exchange transfusion and the plasma viscosity of which was thereby altered by using exchange solutions of different composition to alter plasma viscosity and thus whole blood viscosity independently from hematocrit. Raising the gammaglobulin concentration to approximately 40 mg/ml plasma in the rats almost totally blunted the rise in serum EPO levels despite a fall of the hematocrit to 20%. Determination of renal EPO mRNA levels by RNase protection revealed that the reductions in serum EPO levels at higher plasma viscosities were paralleled by reductions in renal EPO mRNA levels. Taken together, our findings suggest that plasma viscosity may be a significant inhibitory modulator of anemia-induced EPO formation. The increased plasma viscosity in patients with hypergammaglobulinemias may therefore contribute to the inappropriate EPO production, which is a major reason for the anemia developing in these patients.

Adult↗
PubMed1981

Prognostic value of initial blood viscosity on vascular surgery and treatment in peripheral disease.

The correlation between extent of arteriosclerosis and blood viscosity, and the reduction in viscosity after successful surgery support the hypothesis that a raised viscosity is a consequence rather than a cause of arteriosclerosis. Measurement of blood viscosity was of little practical help to our team of vascular surgeons when they were faced with the problem of which reconstruction to do and when to do the procedure on a particular patient. The results of our studies show that in patients with arteriosclerosis, in whom only the major arteries are affected, the viscosity of the blood is not grossly abnormal and a knowledge of the blood viscosity does little to influence treatment. Patients with peripheral vascular disease affecting the small arteries and arterioles often have a high blood viscosity. In these circumstances manipulation of blood viscosity by hemodilution or drugs may be of benefit, and there is evidence that isoxsuprine given intravenously can achieve a reduction in viscosity.

Arteriosclerosis↗
PubMed1980

The effects of age and cigarette-smoking on blood and plasma viscosity in men.

We measured blood viscosity and its major determinants (haematocrit, plasma fibrinogen and plasma viscosity) in 90 apparently healthy men aged 16 to 80 years. Cigarette-smokers (n = 45) had higher levels of blood viscosity, haematocrit and fibrinogen (p less than 0.001) and plasma viscosity (p less than 0.025) than non-smokers (n = 45). Blood viscosity was still higher in smokers after correction to a standard haematocrit (p less than 0.02). Fibrinogen, corrected blood viscosity and plasma viscosity rose with age in both groups, but young smokers had prematurely elevated levels of these variables and less pronounced rises with age. These results show that age and cigarette-smoking must be considered in studies of blood and plasma viscosity, and provide further evidence for an association between viscosity and arterial disease.

Adolescent↗
PubMed1992

Blood viscosity and optimal hematocrit in preterm and full-term neonates in 50- to 500-micrometer tubes.

Blood viscosity is an important determinant of blood flow resistance. Because a substantial part of flow resistance arises in small arteries and arterioles with diameters of 100 microns and less, rheologic properties of blood from preterm infants (24 to 36 wk of gestation), full-term neonates, and adults were measured in glass tubes with diameters of 50, 100, and 500 microns for a wide range of adjusted feed hematocrits (0.15-0.70). At each of the feed hematocrits, blood viscosity decreased when going from a 500-microns tube to a 50-microns tube. The viscosity reduction increased with increasing hematocrit. Moreover, the viscosity reduction was more pronounced in the neonates than in the adults. At a hematocrit of 0.70, the viscosity reduction averaged 56% in preterm infants, 50% in full-term neonates, and 39% in adults (p less than 0.005). However, the viscosity reductions at a hematocrit of 0.30 were only 35, 29, and 19%, respectively (p less than 0.05). In all four groups, blood viscosity increased exponentially with increasing hematocrit. The steepness of the hematocrit-viscosity curves decreased with decreasing tube diameter and with decreasing maturity of the infants. Erythrocyte transport efficiency (hematocrit/blood viscosity) was calculated to estimate the optimal hematocrit (i.e. hematocrit with maximum erythrocyte transport). In 500-microns tubes, the optimal hematocrit was about 0.40 in all of the groups. In 100-microns tubes, the optimal hematocrit was 0.44 +/- 0.05 in the adults and 0.52 +/- 0.04 in the neonates (p less than 0.05). In 50-microns tubes, the optimal hematocrit was 0.51 +/- 0.04 in adults and 0.60 +/- 0.05 in the neonates.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2004

Measurement of fluid viscosity at microliter volumes using quartz impedance analysis.

The purpose of this work was to measure viscosity of fluids at low microliter volumes by means of quartz crystal impedance analysis. To achieve this, a novel setup was designed that allowed for measurement of viscosity at volumes of 8 to 10 microL. The technique was based on the principle of electromechanical coupling of piezoelectric quartz crystals. The arrangement was simple with measurement times ranging from 2 to 3 minutes. The crystal setup assembly did not impose any unwanted initial stress on the unloaded quartz crystal. Quartz crystals of 5- and 10-MHz fundamental frequency were calibrated with glycerol-water mixtures of known density and viscosity prior to viscosity measurements. True frequency shifts, for the purpose of this work, were determined followed by viscosity measurement of aqueous solutions of sucrose, urea, PEG-400, glucose, and ethylene glycol at 25 degrees C +/- 0.5 degrees C. The measured viscosities were found to be reproducible and consistent with the values reported in the literature. Minor inconsistencies in the measured resistance and frequency shifts did not affect the results significantly, and were found to be experimental in origin rather than due to electrode surface roughness. Besides, as expected for a viscoelastic fluid, PEG 8000 solutions, the calculated viscosities were found to be less than the reported values due to frequency dependence of storage and loss modulus components of complex viscosity. From the results, it can be concluded that the present setup can provide accurate assessment of viscosity of Newtonian fluids and also shows potential for analyzing non-Newtonian fluids at low microliter volumes.

Electric Impedance↗
PubMed1994

High-dose intravenous immunoglobulin and serum viscosity: risk of precipitating thromboembolic events.

High-dose intravenous immunoglobulin (IVIg) can increase blood viscosity in vitro and has been associated with cardiovascular or cerebrovascular thromboembolism. Because thromboembolic events were observed in two (3%) of 65 patients we treated with IVIg, we measured serum viscosity serially in 13 patients (five with amyotrophic lateral sclerosis [ALS], eight with IgM paraproteinemic polyneuropathy) before and immediately after each of three consecutive monthly infusions of IVIg. We correlated changes in viscosity with serial determinations of the total serum IgG, IgM, and IgA before and after each infusion. Serum viscosity increased after IVIg in all the patients by 0.1 to 1.0 centipoise (cp) (mean, 0.55 cp). In three ALS patients and in all the patients with paraproteinemic polyneuropathy, serum viscosity exceeded the upper limit of normal (normal, 1.5 to 1.9 cp) and increased as high as 2.6 cp. The increase in viscosity occurred immediately after completion of the infusion, declined over 1 month, and appeared to correlate best with the serum IgG level, which after the infusions was as high as 6,160 mg/dl (normal, 545 to 1,560 mg/dl). I conclude that IVIg increases serum viscosity and in many patients can cross the symptomatic threshold level. Because increased serum viscosity can impair blood flow and trigger a cardiovascular or cerebrovascular thromboembolic event, IVIg should be used judiciously and with concurrent monitoring of serum viscosity in elderly patients and patients with cryoglobulinemia, monoclonal gammopathies, high lipoproteins, or preexisting vascular disease.

Adult↗
PubMed2000

Effects of streptokinase and deoxyribonuclease on viscosity of human surgical and empyema pus.

STUDY OBJECTIVE: To investigate the effects of streptokinase and deoxyribonuclease (DNase) on the viscosity of pus to assess whether the DNase in the old preparation of streptokinase-streptodornase used intrapleurally to treat empyema was contributing to easier drainage of pus compared with purified streptokinase. DESIGN: In vitro measurement of pus viscosity. PATIENTS: Pus from three patients with surgically drained soft tissue abscesses and from six patients with empyema thoracis of varying etiology was studied. INTERVENTIONS: Pus samples were incubated with saline solution as control and with streptokinase, streptokinase-streptodornase, human recombinant DNase, and a mixture of streptokinase and DNase in concentrations approximating those achieved in clinical practice. RESULTS: Purified streptokinase had little effect on pus viscosity, with a mean reduction of 11.1% in the surgical specimens and 1.7% in the empyema samples. Streptokinase-streptodornase reduced viscosity by a mean of 52.8% in the surgical samples and 94.8% in the empyema samples. Human recombinant DNase reduced viscosity by a mean of 32. 79% in surgical samples and 93.4% in empyema samples. Adding streptokinase to human recombinant DNase produced no further reduction in viscosity. Final viscosities in samples treated with DNase were very similar whatever the starting viscosity. CONCLUSIONS: DNase significantly reduces pus viscosity, whereas streptokinase has little or no effect, and in empyema may work simply by breaking down loculations. Clinical studies should be undertaken to see if these in vitro changes produce clinical benefits. The simple viscometer devised for these experiments may also prove useful in other contexts.

Deoxyribonucleases↗
PubMed1991

Effects of the non-Newtonian viscosity of blood on flows in a diseased arterial vessel. Part 1: Steady flows.

Effects of the non-Newtonian viscosity of blood on a flow in a coronary arterial casting of man were studied numerically using a finite element method. Various constitutive models were examined to model the non-Newtonian viscosity of blood and their model constants were summarized. A method to incorporate the non-Newtonian viscosity of blood was introduced so that the viscosity could be calculated locally. The pressure drop, wall shear stress and velocity profiles for the case of blood viscosity were compared for the case of Newtonian viscosity (0.0345 poise). The effect of the non-Newtonian viscosity of blood on the overall pressure drop across the arterial casting was found to be significant at a flow of the Reynolds number of 100 or less. Also in the region of flow separation or recirculation, the non-Newtonian viscosity of blood yields larger wall shear stress than the Newtonian case. The origin of the non-Newtonian viscosity of blood was discussed in relation to the viscoelasticity and yield stress of blood.

Biomechanical Phenomena↗
PubMedDate not supplied

Viscosity of polymer solution phase and other factors controlling the dissolution of theophylline microspheres prepared by the emulsion solvent evaporation method.

The objectives of this investigation are to evaluate the effect of the viscosity of polymer solution phase on microsphere properties, especially the drug release characteristics since no studies on this formulation variable have been reported. Also, since it is known that polymer molecular weight affects both the viscosity of the polymer solution and the release properties of microspheres, the interaction of these factors was studied. Microspheres with 33% theoretical drug loading of anhydrous theophylline core material were prepared by the emulsion solvent evaporation method. Two cellulose acetate butyrate polymers, (CAB381-2, CAB381-20), chemically similar but having different molecular weights, were used to prepare different polymer solutions having different apparent viscosities in acetone. A Brookfield viscometer was used to evaluate the viscosities of polymer solutions. Dissolution rates of microspheres prepared from the polymer solutions were inversely related to the initial polymer solution viscosities for both CAB381-2 and CAB381-20. The times for the release of 30 and 50% of the drug from the microspheres have a linear relationship with initial polymer solution viscosity. Initial release was significantly decreased with increasing polymer solution viscosity. Unlike CAB381-2 microspheres which follow Higuchi spherical matrix release kinetics, microspheres prepared from the higher molecular weight polymer (CAB381-20) showed extended release dissolution profiles with near zero order kinetics. It is evident that both the polymer solution viscosity and the molecular weight have an effect on the drug release from microspheres. These results suggest that release rates of matrix microspheres could be predictably optimized by adjusting the viscosity of polymer solutions.

Delayed-Action Preparations↗
PubMed1992

Measurement of viscosity of human semen with a rotational viscometer.

The viscosity of 130 human seminal plasma samples was studied with a rotational viscometer instead of by the traditional subjective rating method. The average seminal viscosity one hour after ejaculation was 9.35 +/- 0.99 centipoise (cps), which was statistically identical to that in the third hour (8.63 +/- 0.77 cps). Seminal viscosity showed a significant negative correlation with the percentage of motile sperm (p < 0.05); however, no significant correlation between seminal viscosity and sperm concentration could be found (r = -0.15, p = 0.098). The seminal viscosity of the oligoasthenospermic group was significantly higher than that of the normospermic group (p < 0.01); there was also a trend towards higher viscosity in the semen of asthenospermia and oligospermia when compared with the normospermic group. It is concluded that seminal viscosity may be higher in cases of poor-quality semen; however, sperm motility and concentration are not the sole determinants of viscosity. Determining the seminal viscosity with this rapid, objective and quantitative method is valuable in identifying and treating the subgroup of infertile men with viscid semen.

Humans↗
PubMed1992

How blood viscosity influences changes in circulation during pregnancy?

The changes of whole blood viscosity and plasma viscosity were studied in 15 normal non-pregnant women, and 120 normal pregnant women ranging from 8 to 39 weeks of gestation. The values of whole blood viscosity during normal pregnancy were significantly lower from 20 to 31 weeks of gestation than those in the other periods of gestation, and there was a positive correlation between whole blood viscosity and hematocrit. Plasma viscosity, however, did not change significantly during pregnancy. There was no correlation between whole blood viscosity and plasma viscosity, and there was also no correlation between plasma viscosity and plasma fibrinogen concentration. These findings suggest that decreases in whole blood viscosity, resulting from the change of packed-cell volume, may strongly contribute hemorheologically to the decrease in peripheral resistance during the second trimester.

Blood Circulation↗
PubMed2003

Correlations between the severity of retinopathy in diabetic patients and whole blood and plasma viscosity.

UNLABELLED: The aim of this study was to correlate the severity of retinopathy in diabetic patients with the whole blood and plasma viscosity. The studies were performed on 52 patients suffering from type II diabetes mellitus with non-proliferative retinopathy (25 men and 27 females, mean age of patients 64+/-6.5 years). The mean duration of diabetes treatment was 13.7 years. The control group consisted of 43 healthy persons (20 men and 23 women, the mean age of controls was 55.9+/-9.2 years). Blood samples were taken from patients immediately after ophthalmological examination from anticubital vein and anticoagulated with K2EDTA. The symptoms of retinopathy were: macular edemas, microaneurysms, hard and soft exudates and hemorrhagic focuses. The severity of particular signs of retinopathy was expressed in a three point scale. The total number of rank points was correlated with blood and plasma viscosity, moreover with eyes acuity. Blood viscosity measurements were performed with the use of cone-plate Brookfield's viscometer at shear rate 150 s(-1), and plasma viscosity with capillary Ubbelohd's viscometer. Besides the viscometric examinations hematocrit, fibrinogen, blood morphology, total cholesterol concentration, LDL-cholesterol, HDL-cholesterol, triglycerides, blood glucose concentration and glycosylated hemoglobin were examined. The whole blood viscosity, the corrected blood viscosity adjusted to 45% of hematocrit were significantly higher in diabetics (p<0.001). The whole blood relative viscosity was also significantly elevated in diabetic patients (p<0.002). The correlation between visual acuity and rank point of retinopathy severity was negative (r= -0.91, p<0.001). The retinopathy severity was positively correlated with whole blood and plasma viscosity (r=0.51; p<0.001 and r=0.4; p<0.005, respectively). CONCLUSION: Elevated blood and plasma viscosity may play an additional and significant role in the development of diabetic retinopathy.

Aged↗
PubMed1990

Increased whole blood viscosity during coronary artery bypass surgery. Studies to evaluate the effects of soluble fibrin and poloxamer 188.

This study was designed to test the hypothesis that soluble fibrin complexes resulting from the trauma of surgery could produce elevated blood viscosity, to characterize the soluble fibrin polymers, and to evaluate in vitro the effect of a new hemorheologic agent, poloxamer 188, on viscosity in these abnormal situations. Ten patients undergoing aortocoronary bypass surgery were studied before and at various times after surgery. By 6 h after surgery, the mean hematocrit decreased by 23%, fibrinogen decreased 48%, and erythrocyte sedimentation rate decreased 33%, whole blood viscosity at a low shear rate rose on average of 69% and soluble fibrin rose 118%. Over the 6-day observation period, the concentrations of soluble fibrin paralleled the changes in viscosity, whereas the concentrations of fibrinogen varied nearly inversely with viscosity. The effects of various forms of fibrinogen and fibrin were tested by additions to normal blood. Soluble fibrin polymers, but not fibrin monomers, increased blood viscosity two to three fold. Poloxamer 188 reduced the viscosity of all patient samples to the normal range. These data support the hypothesis that increased whole blood viscosity at low shear rates is caused by hydrophobic adhesion of fibrin polymers to red cells and that poloxamer 188 normalizes viscosity by effectively disrupting the weak hydrophobic bonds.

Biopolymers↗
PubMed1996

[Changes in erythrocyte rigidity and neonatal relative viscosity during the adaptation of the newborn to extrauterine life. Observations on term and premature newborns].

BACKGROUND: The deformability of the red blood cell is a important factor in the blood viscosity and it is related with the blood viscosity and it is modified by the plasma biochemical characteristics and the composition of hemoglobin in the red blood cell. In this study, we want to compare the rheologic characteristics in the blood of cord umbilical in term and preterm newborns during the first 24 hours of life and we want to evaluate that hemorheologic modifications are explained because of the different gestational age. METHODS: We studied 191 newborns in our maternity from 1989 until 1990. We analyzed four groups: In the first group (n = 40) of preterm newborn (gestational age < 37 weeks); in the second group (n = 72) of term newborns (gestational age > 37 weeks); the samples were obtained from umbilical artery immediately after the umbilical cord clamp; in the third group (n = 38) of preterm newborn and the fourth group of term newborns (n = 41) was studied during 24 hours after delivery. We analyzed the plasma viscosity, the viscosity of red blood cell (RBC) content and the RBC rigidity calculated by Taylor's coefficient. RESULTS: The RBC rigidity is greater during the post-delivery period, which could be in relation with the greater values of plasma viscosity and the RBC content during the postnatal period. The comparisons between umbilical cord of term and preterm newborn they did not show differences for the RBC content viscosity and the relative viscosity. The plasma viscosity of the umbilical cord was discretely greater in the term newborn though in meaning limits statistics. In umbilical cord the hematocrit does not defer significantly between term and preterm newborns. CONCLUSIONS: Following our data we can make firm that the RBC rigidity is increased after the delivery in term and preterm newborns and the greater relative viscosity observed in newborn to term during the first life extrauterine days in related fundamentally to the corporal liquids readjustment that occurs after of delivery.

Adaptation, Physiological↗
PubMed1998

Comparison of blood viscosity in red-eared sliders (Trachemys scripta) adapted to cold and room temperature.

Red-eared sliders (Trachemys scripta) in their northern range undergo hibernation at temperatures of about 5 degrees C, which may result in a profound bradycardia and a drop in blood pressure leading to very slow blood flows. Blood viscosity increases with decreasing temperature and at low shear rates associated with slow blood flows. To investigate the effects of temperature on the blood viscosity of these animals, 20 red-eared sliders were randomly assigned to each of two groups, cold environment (5 degrees C) or room-temperature environment (25 degrees C). At the end of 5 months treatment, hematocrit values, plasma protein concentration, and whole-blood viscosity values were determined for each turtle. Blood viscosity measurements were determined at five shear rates (3.75, 15, 30, 75, and 150 s-1) at 5 degrees C and 25 degrees C for all animals. No significant differences were found in hematocrit or plasma protein values between cold-adapted and room temperature-adapted animals. Whole-blood viscosity between groups at any shear rate at a temperature of 5 degrees C was also nonsignificant. The only significant difference in blood viscosity between turtles adapted to cold and room temperature occurred at a shear rate of 3.75 s-1 at 25 degrees C. The whole-blood viscosity of red-eared sliders, whether adapted to cold or to room temperature, tended to be lower as compared to other vertebrates under similar conditions of temperature, shear rate, and hematocrit. This innate lower blood viscosity may compensate for the potential detrimental effects on blood viscosity brought about by the low temperatures and decreased shear rates that occur in these animals during hibernation.

Adaptation, Physiological↗
PubMed1997

The Effect of Diameter Ratio and Volume Ratio on the Viscosity of Bimodal Suspensions of Polymer Latices

Previously, the rheological properties of different sized monodisperse polymer latices of polystyrene and polymethyl methacrylate (PMMA) were determined. This paper describes procedures in which carefully prepared blends of the same monodisperse latices were mixed together to examine the effect of the differences in size between the latices (diameter ratio) on the rheology of the blend. The relative viscosities of these blends were then measured as a function of the total volume fraction and compared with those of the constituent parts. In a bimodal suspension, theory predicts that a maximum packing fraction and hence a minimum viscosity is achieved with 27% small particles by volume. The experiments revealed that a minimum viscosity was obtained with 25% small particles by volume and with a diameter ratio of 7.83. At this diameter ratio, the small particles are able to pass through the triangular pore between the large particles and this essentially leads to an increased maximum packing fraction of the suspension. Hence the suspension will have a lower viscosity. Other diameter ratios at 25% small particles by volume that led to suspensions with lower viscosities were 4.03, 6.37, and 11.15. On the other hand the suspensions with diameter ratios of 2.81 and 5.67 led to increases in viscosity. This is a result of the small particles being too big to fit in the gaps between the large particles. All the other diameter ratios at all the other compositions (i.e., 50 and 75% small particles by volume) resulted in viscosities higher than that obtained for the monodisperse polystyrene latex. These effects may be explained by changes in the value of the maximum packing fraction. An increased maximum packing fraction of the system leads to lower viscosities and vice versa. The results challenge the conventional view that simply increasing the diameter ratio at a fixed composition leads to reduced viscosities and increased maximum packing fractions. This simple picture does not appear to hold for binary suspensions of colloidal particles at every particle size ratios.

Journal Article↗