The Rheology of Saliva

1987 ◽  
Vol 66 (1_suppl) ◽  
pp. 660-666 ◽  
Author(s):  
W. H. Schwarz
Keyword(s):  
Salivary Gland ◽  
Rheological Properties ◽  
Medical Management ◽  
Artificial Saliva ◽  
Salivary Gland Dysfunction ◽  
Shear Dependent Viscosity ◽  
Saliva Analysis ◽  
Whole Saliva ◽  
Saliva Substitutes ◽  
Dependent Viscosity

The rheology of saliva affects the coating and lubrication of oral surfaces and the consistency of ingested foods. Salivary gland dysfunction can cause tissue damage and dysphagia. Therefore, we have considered the problem of designing a synthetic saliva for medical management. Also, we have measured certain rheological properties [shear-dependent viscosity η (k)] and the frequency-dependent moduli [G′(f) and η′(f)] of normal stimulated whole saliva. Analysis of the rheological data and consideration of requirements for using artificial saliva have resulted in a better understanding of the rheological functions of natural saliva and the desirable characteristics of synthetic saliva. In addition, we have measured rheological properties of two commercial saliva substitutes for comparison.

The Rheology of Saliva

1987 ◽  
Vol 66 (2_suppl) ◽  
pp. 660-666 ◽  
Author(s):  
W. H. Schwarz
Keyword(s):  
Salivary Gland ◽  
Rheological Properties ◽  
Medical Management ◽  
Artificial Saliva ◽  
Salivary Gland Dysfunction ◽  
Shear Dependent Viscosity ◽  
Saliva Analysis ◽  
Whole Saliva ◽  
Saliva Substitutes ◽  
Dependent Viscosity

The rheology of saliva affects the coating and lubrication of oral surfaces and the consistency of ingested foods. Salivary gland dysfunction can cause tissue damage and dysphagia. Therefore, we have considered the problem of designing a synthetic saliva for medical management. Also, we have measured certain rheological properties [shear-dependent viscosity η(κ)] and the frequency-dependent moduli [G'(f) and η'(f)] of normal stimulated whole saliva. Analysis of the rheological data and consideration of requirements for using artificial saliva have resulted in a better understanding of the rheological functions of natural saliva and the desirable characteristics of synthetic saliva. In addition, we have measured rheological properties of two commercial saliva substitutes for comparison.

Annular Frictional Pressure Losses During Drilling—Predicting the Effect of Drillstring Rotation

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Arild Saasen
Keyword(s):  
Rheological Properties ◽  
Pressure Loss ◽  
Drilling Fluid ◽  
Axial Flow ◽  
Drilling Fluids ◽  
Unstable Flow ◽  
Pressure Losses ◽  
Shear Dependent Viscosity ◽  
Water Based ◽  
Dependent Viscosity

Controlling the annular frictional pressure losses is important in order to drill safely with overpressure without fracturing the formation. To predict these pressure losses, however, is not straightforward. First of all, the pressure losses depend on the annulus eccentricity. Moving the drillstring to the wall generates a wider flow channel in part of the annulus which reduces the frictional pressure losses significantly. The drillstring motion itself also affects the pressure loss significantly. The drillstring rotation, even for fairly small rotation rates, creates unstable flow and sometimes turbulence in the annulus even without axial flow. Transversal motion of the drillstring creates vortices that destabilize the flow. Consequently, the annular frictional pressure loss is increased even though the drilling fluid becomes thinner because of added shear rate. Naturally, the rheological properties of the drilling fluid play an important role. These rheological properties include more properties than the viscosity as measured by API procedures. It is impossible to use the same frictional pressure loss model for water based and oil based drilling fluids even if their viscosity profile is equal because of the different ways these fluids build viscosity. Water based drilling fluids are normally constructed as a polymer solution while the oil based are combinations of emulsions and dispersions. Furthermore, within both water based and oil based drilling fluids there are functional differences. These differences may be sufficiently large to require different models for two water based drilling fluids built with different types of polymers. In addition to these phenomena washouts and tool joints will create localised pressure losses. These localised pressure losses will again be coupled with the rheological properties of the drilling fluids. In this paper, all the above mentioned phenomena and their consequences for annular pressure losses will be discussed in detail. North Sea field data is used as an example. It is not straightforward to build general annular pressure loss models. This argument is based on flow stability analysis and the consequences of using drilling fluids with different rheological properties. These different rheological properties include shear dependent viscosity, elongational viscosity and other viscoelastic properties.

scholarly journals Cytokine/Chemokine/Growth Factor Profiles Contribute to Understanding the Pathogenesis of the Salivary Gland Dysfunction in Euthyroid Hashimoto’s Thyroiditis Patients

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
K. Morawska ◽  
M. Maciejczyk ◽  
S. Zięba ◽  
Ł. Popławski ◽  
A. Kita-Popławska ◽  
...  
Keyword(s):  
Salivary Gland ◽  
Growth Factors ◽  
Salivary Glands ◽  
Hashimoto’S Thyroiditis ◽  
Clinical Symptoms ◽  
Hormonal Treatment ◽  
Hashimoto's Thyroiditis ◽  
Salivary Gland Dysfunction ◽  
Whole Saliva ◽  
Unstimulated Whole Saliva

Hashimoto’s thyroiditis (HT) is one of the most common autoimmune diseases. It is suggested that, in addition to thyroid gland dysfunction, HT is responsible for impaired secretion from the salivary glands. The aim of this study was to evaluate the extent of symptoms of salivary gland dysfunction. We also assessed the relationship between the levels of selected cytokines, chemokines, and growth factors in unstimulated whole saliva (UWS) and the rate of UWS secretion and symptoms of xerostomia in HT patients. The study group consisted of 25 female patients diagnosed with Hashimoto’s disease in its spontaneous euthyroid state who had never received hormonal treatment. In more than half of the examined patients, we observed the level of UWS secretion below 0.2 mL/min, indicating impaired secretory function of the salivary glands. Moreover, we demonstrated that the clinical symptoms of salivary gland dysfunction worsen with disease duration. Nevertheless, the inflammatory changes occurring in these glands are independent of general inflammation in the course of HT. Our results clearly indicate an abnormal profile of cytokines, chemokines, and growth factors in the UWS of HT euthyroid women as well as the fact that concentrations of IL-6 and IL-1 as well as INF-γ, TNF-α, and IL-12 may be potential biomarkers for salivary gland dysfunction in the course of HT. Furthermore, salivary IL-12 (p40) may be helpful in assessing the progression of autoimmunity-related inflammation in the course of HT. In conclusion, secretory dysfunction of the salivary glands is closely related to autoimmunity-related inflammation in the course of HT, which leads to objective and subjective symptoms of dry mouth.

Annular Frictional Pressure Losses During Drilling: The Effect of Drillstring Rotation

2013 ◽  
Author(s):  
Arild Saasen
Keyword(s):  
Rheological Properties ◽  
Pressure Loss ◽  
Drilling Fluid ◽  
Axial Flow ◽  
Drilling Fluids ◽  
Unstable Flow ◽  
Pressure Losses ◽  
Shear Dependent Viscosity ◽  
Water Based ◽  
Dependent Viscosity

Controlling the annular frictional pressure losses is important in order to drill safely with overpressure without fracturing the formation. To predict these pressure losses, however, is not straightforward. First of all, the pressure losses depend on the annulus eccentricity. Moving the drillstring to the wall generates a wider flow channel in part of the annulus reducing the frictional pressure losses significantly. The drillstring motion itself also affects the pressure loss significantly. The drillstring rotation, even for fairly small rotation rates, creates unstable flow and sometimes turbulence in the annulus even without axial flow. Transversal motion of the drillstring creates vortices that de-stabilize the flow. Consequently, the annular frictional pressure loss is increased even though the drilling fluid becomes thinner because of added shear rate. Naturally, the rheological properties of the drilling fluid play an important role. These rheological properties include more properties than the viscosity as measured by API procedures. It is impossible to use the same frictional pressure loss model for water based and oil based drilling fluids even if their viscosity profile is equal because of the different ways these fluids build viscosity. Water based drilling fluids are normally constructed as a polymer solution while the oil based are combinations of emulsions and dispersions. Furthermore, within both water based and oil based drilling fluids there are functional differences. These differences may be sufficiently large to require different models for two water based drilling fluids built with different types of polymers. In addition to these phenomena washouts and tool joints will create localised pressure losses. These localised pressure losses will again be coupled with the rheological properties of the drilling fluids. In the paper, all the above mentioned different phenomena and their consequences for annular pressure losses will be discussed in detail. Application of Det norske field data will be used as an example. The data cannot be used to build general models. The arguments for this model restriction are based on flow stability analysis and the consequences of using drilling fluids with different rheological properties. These different rheological properties include shear dependent viscosity, elongational viscosity and other viscoelastic properties.

scholarly journals Artificial Saliva: Challenges and Future Perspectives for the Treatment of Xerostomia

2019 ◽  
Vol 20 (13) ◽  
pp. 3199 ◽  
Author(s):  
Dawid Łysik ◽  
Katarzyna Niemirowicz-Laskowska ◽  
Robert Bucki ◽  
Grażyna Tokajuk ◽  
Joanna Mystkowska
Keyword(s):  
Salivary Gland ◽  
Artificial Saliva ◽  
Antimicrobial Properties ◽  
Antimicrobial Effect ◽  
Biological Properties ◽  
Dry Mouth ◽  
Disease Condition ◽  
Saliva Substitutes ◽  
Salivary Substitutes ◽  
Qualitative Changes

The chronic sensation of a dry mouth is a disease condition called xerostomia and affects a large part of the population. Xerostomia is associated with decreased secretion, or more often, qualitative changes in saliva proteins and immunoglobulin concentrations that develop as a result of salivary gland dysfunction. Several reasons causing dry mouth were described, and usually, they include taking medications, diseases or radiotherapy. In some situations, when it is difficult to use salivary stimulants or salivary gland damage is irreversible, the only option might seem to be saliva substitutes. The paper presents the most important aspects considering saliva preparations. The rheological and lubricating properties and the reconstruction of the complex saliva structure has been the main purpose of research. The biological properties of saliva preparations were also widely discussed. As part of the work, the antimicrobial effect of three commercial saliva preparations was tested. Finally, inadequate antimicrobial properties against the strains isolated from the oral cavity were demonstrated. The development of salivary substitutes, in particular, the improvement of antimicrobial properties, can be achieved using nanotechnology, including drug delivery systems containing nanocarriers.

scholarly journals Older age, smoking, tooth loss and denture-wearing but neither xerostomia nor salivary gland hypofunction are associated with low intakes of fruit and vegetables in older Danish adults

2021 ◽  
Vol 10 ◽  
Author(s):  
Anne Marie Lynge Pedersen ◽  
Anja Weirsøe Dynesen ◽  
Berit Lilienthal Heitmann
Keyword(s):  
Salivary Gland ◽  
Tooth Loss ◽  
Vegetable Intake ◽  
Community Dwelling ◽  
Older Age ◽  
Fruit And Vegetables ◽  
Fruit And Vegetable ◽  
Flow Rates ◽  
Whole Saliva ◽  
Salivary Gland Hypofunction

Abstract Xerostomia and salivary gland hypofunction are prevalent conditions in older people and may adversely influence the intake of certain foods, notably fruit and vegetables. Here, we aimed to investigate whether xerostomia and salivary gland hypofunction were associated with a lower intake of fruit and vegetables. The study included 621 community-dwelling adults, mean age 75⋅2 ± 6⋅4 years, 58⋅9 % female, who had participated in the Copenhagen City Heart Study follow-up, and undergone interviews regarding food intake (preceding month), oral and general health (xerostomia, taste alterations, diseases, medication, alcohol consumption and smoking), clinical oral examination and measurements of unstimulated and chewing-stimulated whole saliva flow rates. The average total energy intake (8⋅4 ± 2⋅7 MJ) and protein energy percentage (14⋅8 ± 3⋅1 %) were slightly below recommendations. The average fruit (234⋅7 ± 201⋅2 g/d) and vegetables (317⋅3 ± 157⋅4 g/d) intakes were within recommendations. Xerostomia and hyposalivation were more prevalent in women than in men (16⋅4 v. 7⋅1 %, P < 0⋅001 and 40⋅7 v. 27⋅5 %, P < 0⋅001). Multiple linear regression analyses revealed that older age (β −0⋅009, se 0⋅003, P = 0⋅005), smoking (β −0⋅212, se 0⋅060, P = 0⋅0005) and wearing complete dentures/being partially or fully edentulous (β −0⋅141, se 0⋅048, P = 0⋅003), but neither xerostomia nor salivary flow rates were associated with an inadequate fruit and vegetable intake, after adjustment for covariates. Older age, smoking, tooth loss and denture-wearing were stronger determinants of low fruit and vegetable intakes than xerostomia and salivary hypofunction supporting the importance of dietary counselling and maintenance of oral health and an adequate masticatory performance.

scholarly journals Disease-Induced Changes in Salivary Gland Function and the Composition of Saliva

2021 ◽  
pp. 002203452110048
Author(s):  
G.B. Proctor ◽  
A.M. Shaalan
Keyword(s):  
Salivary Gland ◽  
Sjögren Syndrome ◽  
Healthy Population ◽  
Sjogren Syndrome ◽  
Salivary Gland Function ◽  
Salivary Gland Dysfunction ◽  
Gland Function ◽  
And Function ◽  
The Impact ◽  
Saliva Composition

Although the physiological control of salivary secretion has been well studied, the impact of disease on salivary gland function and how this changes the composition and function of saliva is less well understood and is considered in this review. Secretion of saliva is dependent upon nerve-mediated stimuli, which activate glandular fluid and protein secretory mechanisms. The volume of saliva secreted by salivary glands depends upon the frequency and intensity of nerve-mediated stimuli, which increase dramatically with food intake and are subject to facilitatory or inhibitory influences within the central nervous system. Longer-term changes in saliva secretion have been found to occur in response to dietary change and aging, and these physiological influences can alter the composition and function of saliva in the mouth. Salivary gland dysfunction is associated with different diseases, including Sjögren syndrome, sialadenitis, and iatrogenic disease, due to radiotherapy and medications and is usually reported as a loss of secretory volume, which can range in severity. Defining salivary gland dysfunction by measuring salivary flow rates can be difficult since these vary widely in the healthy population. However, saliva can be sampled noninvasively and repeatedly, which facilitates longitudinal studies of subjects, providing a clearer picture of altered function. The application of omics technologies has revealed changes in saliva composition in many systemic diseases, offering disease biomarkers, but these compositional changes may not be related to salivary gland dysfunction. In Sjögren syndrome, there appears to be a change in the rheology of saliva due to altered mucin glycosylation. Analysis of glandular saliva in diseases or therapeutic interventions causing salivary gland inflammation frequently shows increased electrolyte concentrations and increased presence of innate immune proteins, most notably lactoferrin. Altering nerve-mediated signaling of salivary gland secretion contributes to medication-induced dysfunction and may also contribute to altered saliva composition in neurodegenerative disease.

Stability of Shear-Thickening Liquids Between Rotating Cylinders

2010 ◽  
Author(s):  
Nariman Ashrafi ◽  
Habib Karimi Haghighi
Keyword(s):  
Couette Flow ◽  
Dynamical Behavior ◽  
Shear Thickening ◽  
Shear Thinning ◽  
Taylor Vortex ◽  
Shear Dependent Viscosity ◽  
Shear Thinning Fluids ◽  
Shear Thickening Fluids ◽  
The Stability ◽  
Dependent Viscosity

The effects of nonlinearities on the stability are explored for shear thickening fluids in the narrow-gap limit of the Taylor-Couette flow. It is assumed that shear-thickening fluids behave exactly as opposite of shear thinning ones. A dynamical system is obtained from the conservation of mass and momentum equations which include nonlinear terms in velocity components due to the shear-dependent viscosity. It is found that the critical Taylor number, corresponding to the loss of stability of Couette flow becomes higher as the shear-thickening effects increases. Similar to the shear thinning case, the Taylor vortex structure emerges in the shear thickening flow, however they quickly disappear thus bringing the flow back to the purely azimuthal flow. Naturally, one expects shear thickening fluids to result in inverse dynamical behavior of shear thinning fluids. This study proves that this is not the case for every point on the bifurcation diagram.

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