Search results for "RHEOLOGY"
showing 10 items of 430 documents
Are abdominal obesity and body mass index independent predictors of hemorheological parameters?
2012
There is an association between obesity and rheological blood behavior [2, 4–7]. In this sense we have read with interest the recently published article by Brun et al. [1] in this journal. The authors evaluate, in a population of 430 subjects, the relationship between abdominal obesity and body mass index (BMI) with blood viscosity, and conclude that both anthropometric parameters are associated with increased blood viscosity but by different mechanisms, where the waist to hip ratio is a better predictor for blood viscosity than BMI. It is striking that in this study the authors do not indicate the variables included in the stepwise multivariate regression model, where plasma lipids, glucos…
Hemorheological profile in primary and secondary Raynaud's phenomenon. Influence of microangiopathy.
2013
Raynaud's phenomenon (RP) is an episodic peripheral circulatory disorder characterized by local artery spams in subjects exposed to cold or emotional stress. It is not well-established whether RP patients show an altered rheological profile, mostly due to patient classification and clinical severity. We aimed to compare the hemorheological profile in patients with primary and secondary RP with a healthy control group. Eighteen primary RP, 22 secondary RP and 22 healthy controls, were included in the study. RP patients were also divided according to the presence of digital ulcers (7 with, 33 without). Biochemical and hemorheological variables were analyzed, including glucose, triglycerides, …
Coagulation, fibrinolysis and haemorheology in premenopausal obese women with different body fat distribution
1994
Recently waist/hip ratio (WHR), a marker of body fat distribution, has been described as a risk factor for cardiovascular disease (CVD). The aim of the present study was to evaluate the influence of body fat distribution on metabolic, haemostatic and haemorheological pattern in premenopausal obese women with different WHR. Fourty premenopausal obese women were subdivided into two groups, matched for age and body mass index (BMI): 20 women with abdominal obesity (WHR = 0.94 +/- 0.02) and 20 women with peripheral obesity (WHR = 0.77 +/- 0.03). Twenty nonobese women were recruited as control group. The abdominal obesity group had significantly higher blood glucose, triglycerides, total cholest…
Practical strategies for stable operation of HFF-QCM in continuous air flow
2013
Currently there are a few fields of application using quartz crystal microbalances (QCM). Because of environmental conditions and insufficient resolution of the microbalance, chemical sensing of volatile organic compounds in an open system was as yet not possible. In this study we present strategies on how to use 195 MHz fundamental quartz resonators for a mobile sensor platform to detect airborne analytes. Commonly the use of devices with a resonant frequency of about 10 MHz is standard. By increasing the frequency to 195 MHz the frequency shift increases by a factor of almost 400. Unfortunately, such kinds of quartz crystals tend to exhibit some challenges to obtain a reasonable signal-to…
Thermo-responsive hydrogels from cellulose-based polyelectrolytes and catanionic vesicles for biomedical application.
2016
In this study, negatively charged catanionic vesicles/hydrophobically modified hydroxyethylcellulose polymers thermo-responsive hydrogels have been fabricated. Vesicular aggregates were found to act as multifunctional junctions for networking of modified-cellulose water solutions. The contributions of the electrostatic and hydrophobic interactions were evaluated by changing either vesicles composition or the polymer hydrophobic substitution. Thermal-induced size and lamellarity of hydrogel-enclosed vesicles were detected, with further polygonal shape changes induced by cellulose-based polymer addition. The thermal transition was also found to tune hydrogel mechanical behaviour. The network …
Impact of molecular weight on the formation of electrosprayed chitosan microcapsules as delivery vehicles for bioactive compounds.
2016
The molecular weight of chitosan is one of its most determinant characteristics, which affects its processability and its performance as a biomaterial. However, information about the effect of this parameter on the formation of electrosprayed chitosan microcapsules is scarce. In this work, the impact of chitosan molecular weight on its electrosprayability was studied and correlated with its effect on the viscosity, surface tension and electrical conductivity of solutions. A Discriminant Function Analysis revealed that the morphology of the electrosprayed chitosan materials could be correctly predicted using these three parameters for almost 85% of the samples. The suitability of using elect…
Ionic liquid gels and antioxidant carbon nanotubes: Hybrid soft materials with improved radical scavenging activity
2019
Hypothesis: Performances of materials are frequently affected by the action of radicals that can induce their degradation. To overcome the above issue, natural antioxidants (AOs) can be added during manufacturing. Considering the high instability of AOs, they have been adsorbed on carbon nanomaterials surface. However, the inclusion of functionalized carbon nanomaterials into gel matrix could enhance the antioxidant efficiency and represent an easy way to disperse and handle the active species.Experiments: Carboxypropyl functionalized carbon nanotubes (f-CNT), pure or with physically adsorbed alpha-tocopherol (f-CNT-VE) and quercetin (f-CNT-Q), were incorporated in some ionic liquid gels (I…
Probing the internal environment of PVP networks generated by irradiation with different sources
2010
Poly(N-vinyl-2-pyrrolidone) (PVP) hydrogels have been synthesised from the aqueous solutions of the same linear polymer by two different radiation sources: electron beams and UV rays. The present investigation couples conventional hydrogel characterisation techniques with the study of the partition equilibria, fluorescence behaviour and release of two different molecular probes, 1-anilino-8-naphthalene sulphonate (ANS) and Thioflavin T (ThT). The two probes have comparable molecular weight and different structural and optical properties. The chemical networks produced upon irradiation in different experimental conditions presented quite distinctive mechanical spectra, yielded to different…
Experimental modeling of viscous inclusions in a circular high-strain shear rig: Implications for the interpretation of shape fabrics and deformed en…
2002
[1] Deformation experiments with initially spherical and prolate viscous inclusions suspended in a viscous Newtonian matrix in a circular high strain annular shear rig provide insights on the shape development of inclusions in high strain shear zones during progressive deformation. Inclusions with a specific viscosity ratio with respect to the matrix material show distinct types of three-dimensional shape development. For instance, at a high viscosity ratio between matrix and inclusion a pulsating ellipsoid develops, which both continuously rotates and changes its shape from a sphere to an ellipsoid and back to a sphere. The experiments show that the shape of an inclusion that has a viscosi…