scholarly journals Numerical Sensitivity Analysis for Dielectric Characterization of Biological Samples by Open-Ended Probe Technique

Sensors ◽  
2020 ◽  
Vol 20 (13) ◽  
pp. 3756
Author(s):  
Marta Cavagnaro ◽  
Giuseppe Ruvio
Keyword(s):  
Water Content ◽  
Ex Vivo ◽  
High Water ◽  
Biological Tissues ◽  
Fundamental Aspect ◽  
High Water Content ◽  
Insertion Depth ◽  
Dielectric Characterization

Dielectric characterization of biological tissues has become a fundamental aspect of the design of medical treatments based on electromagnetic energy delivery and their pre-treatment planning. Among several measuring techniques proposed in the literature, broadband and minimally-invasive open-ended probe measurements are best-suited for biological tissues. However, several challenges related to measurement accuracy arise when dealing with biological tissues in both ex vivo and in vivo scenarios such as very constrained set-ups in terms of limited sample size and probe positioning. By means of the Finite Integration Technique in the CST Studio Suite® software, the numerical accuracy of the reconstruction of the complex permittivity of a high water-content tissue such as liver and a low water-content tissue such as fat is evaluated for different sample dimensions, different location of the probe, and considering the influence of the background environment. It is found that for high water-content tissues, the insertion depth of the probe into the sample is the most critical parameter on the accuracy of the reconstruction. Whereas when low water-content tissues are measured, the probe could be simply placed in contact with the surface of the sample but a deeper and wider sample is required to mitigate biasing effects from the background environment. The numerical analysis proves to be a valid tool to assess the suitability of a measurement set-up for a target accuracy threshold.

scholarly journals Fluid Structural Analysis of Urine Flow in a Stented Ureter

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
J. Carlos Gómez-Blanco ◽  
F. Javier Martínez-Reina ◽  
Domingo Cruz ◽  
J. Blas Pagador ◽  
Francisco M. Sánchez-Margallo ◽  
...  
Keyword(s):  
Computational Models ◽  
Mechanical Characterization ◽  
Ex Vivo ◽  
Biological Tissues ◽  
Urine Flow ◽  
Computational Environment ◽  
Computational Fluid Dynamics Cfd

Many urologists are currently studying new designs of ureteral stents to improve the quality of their operations and the subsequent recovery of the patient. In order to help during this design process, many computational models have been developed to simulate the behaviour of different biological tissues and provide a realistic computational environment to evaluate the stents. However, due to the high complexity of the involved tissues, they usually introduce simplifications to make these models less computationally demanding. In this study, the interaction between urine flow and a double-J stented ureter with a simplified geometry has been analysed. The Fluid-Structure Interaction (FSI) of urine and the ureteral wall was studied using three models for the solid domain: Mooney-Rivlin, Yeoh, and Ogden. The ureter was assumed to be quasi-incompressible and isotropic. Data obtained in previous studies from ex vivo and in vivo mechanical characterization of different ureters were used to fit the mentioned models. The results show that the interaction between the stented ureter and urine is negligible. Therefore, we can conclude that this type of models does not need to include the FSI and could be solved quite accurately assuming that the ureter is a rigid body and, thus, using the more simple Computational Fluid Dynamics (CFD) approach.

Preparation and characterization of modified chitosan for in vitro controlled release of vitamin B12

2013 ◽  
Vol 33 (8) ◽  
pp. 757-765 ◽  
Author(s):  
Ahmed Awadallah-F ◽  
Tahia B. Mostafa
Keyword(s):  
Water Content ◽  
Monomer Concentration ◽  
High Water ◽  
High Water Content ◽  
Vitamin B ◽  
Acryloyl Chloride ◽  
Modified Chitosan ◽  
Increase With Increase

Abstract Graft copolymerization of acrylonitrile and acryloyl chloride on to chitosan was prepared by γ-rays. Optimization of the grafting (%) was studied. The grafting (%) was observed to increase with increase in the irradiation dose and monomer concentration. The grafting percentages were about 52% and 36% from polyacrylonitrile and poly(acryloyl chloride), respectively. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterize the specimens. The modified chitosan was loaded with vitamin B12, demonstrated nearly 5.0±2.3% and 50.1±4.5% release in the media of pH 1.2 and 6.8, respectively, for amidoximated chitosan-grafted polyacrylonitrile and 3.6±1.1% and 36±2.4% in pH 1.2 and 6.8, respectively, for chitosan-grafted poly(acryloyl chloride), as determined by a traditional dissolution model. The modified chitosan specimens that uploaded with vitamin B12 displayed a more decremental release in the acidic medium than the neutral one. However, in order to incorporate in vivo gastrointestinal conditions, such as acidic pH and high water content in the stomach, low water content, and the presence of semi-solid mass in the large intestine, a new model, called flow through diffusion cell, was also used to study the drug release. The results of the two approaches produced different release profiles at the same pH values.

scholarly journals Characterization of the Undrained Shear Strength of Expansive Soils of High Water Content

2018 ◽  
Vol 206 ◽  
pp. 01002
Author(s):  
Zheng Su ◽  
Daokun Qi ◽  
Xinju Guo ◽  
Xiaojuan Xi ◽  
Liang Zhang
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Friction Angle ◽  
High Water ◽  
Ease Of Use ◽  
Triaxial Tests ◽  
High Water Content

In recent years, engineering constructions increase rapidly in western and central areas of China, where expansive soil widely distributes. Since expansive soil is sensitive to water content, the characterization of its shear strength should be carefully conducted. For simplicity and ease of use, the Mohr-Coulomb criterion is often adopted to describe the shear strength of expansive soil. In this paper, the physical meaning of the cohesion and frictional strength of expansive soil are explained, and the variations of the strength parameters with water content are investigated. By fitting to the experimental results from direct shear test and triaxial tests, the changing characteristics of cohesion and friction angle with water content are obtained.

Undernutrition in grazing sheep. III.* Body composition and its estimation in vivo

1972 ◽  
Vol 23 (3) ◽  
pp. 511 ◽  
Author(s):  
DJ Farrell ◽  
TF Reardon
Keyword(s):  
Body Weight ◽  
Water Content ◽  
Tritiated Water ◽  
Body Part ◽  
High Water ◽  
The Body ◽  
High Water Content ◽  
Regression Equations ◽  
Free Body

Twenty-four sheep, 12 fitted with rumen cannulae, were divided into three similar groups and kept at pasture. The grazing intake of group A was not restricted, but groups B and C were undernourished for a period of about 4 months and were then maintained in thin condition for a further 9 months, when all sheep were killed. The mean fat content was then 27, 9, and 5% of mean body weight in groups A, B, and C respectively. Undernourished sheep had a significantly higher (P < 0.01) water content in the fat-free empty body than well-nourished sheep. Multiple regression equations relating the fat, protein, and estimated energy contents of the body to tritiated water space and body weight differed between well-nourished and undernourished sheep. This was due to the larger amount of water in the rumell-reticulum of thin sheep and to the high water content of their fat-free body. __________________ *Part II, Aust. J. Agric. Res., 23: 499 (1972)

scholarly journals Spatiotemporal Analysis of Hydration Mechanism in Sodium Alginate Matrix Tablets

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 646
Author(s):  
Ewelina Juszczyk ◽  
Piotr Kulinowski ◽  
Ewelina Baran ◽  
Artur Birczyński ◽  
Dorota Majda ◽  
...  
Keyword(s):  
Water Content ◽  
Spatial Resolution ◽  
Water Distribution ◽  
Spatiotemporal Analysis ◽  
High Water ◽  
Matrix Tablets ◽  
High Water Content ◽  
Hydrated Layer ◽  
Order Of Magnitude

Methods of spatiotemporal characterization of nonequilibrated polymer based matrices are still immature and imperfect. The purpose of the study was to develop the methodology for the spatiotemporal characterization of water transport and properties in alginate tablets under hydration. The regions of low water content were spatially and temporally sampled using Karl Fisher and Differential Scanning Callorimetry (spatial distribution of freezing/nonfreezing water) with spatial resolution of 1 mm. In the regions of high water content, where sampling was infeasible due to gel/sol consistency, magnetic resonance imaging (MRI) enabled characterization with an order of magnitude higher spatial resolution. The minimally hydrated layer (MHL), infiltration layer (IL) and fully hydrated layer (FHL) were identified in the unilaterally hydrated matrices. The MHL gained water from the first hour of incubation (5–10% w/w) and at 4 h total water content was 29–39% with nonfreezing pool of 28–29%. The water content in the IL was 45–47% and at 4 h it reached ~50% with the nonfreezing pool of 28% and T2 relaxation time < 10 ms. The FHL consisted of gel and sol layer with water content of 85–86% with a nonfreezing pool of 11% at 4 h and T2 in the range 20–200 ms. Hybrid destructive/nondestructive analysis of alginate matrices under hydration was proposed. It allowed assessing the temporal changes of water distribution, its mobility and interaction with matrices in identified layers.

scholarly journals Preparation and characterization of a supramolecular hydrogel made of phospholipids and oleic acid with a high water content

2020 ◽  
Vol 8 (1) ◽  
pp. 161-167 ◽  
Author(s):  
Kirian Talló ◽  
Manel Bosch ◽  
Ramon Pons ◽  
Mercedes Cocera ◽  
Olga López
Keyword(s):  
Oleic Acid ◽  
Water Content ◽  
High Water ◽  
Structured Lipid ◽  
High Water Content ◽  
Supramolecular Hydrogel ◽  
Gelling Agents

Formation of a structured lipid hydrogel able to accommodate a high amount of water (95%) without needing gelling agents.

Synthesis and Characterization of Monosaccharide-Containing 2-(α-D-mannopyranosyloxy)Ethyl Methacrylate as a Surface Modifier for Hydrogels

2020 ◽  
Vol 20 (9) ◽  
pp. 5609-5613
Author(s):  
Shengnan Wu ◽  
Chanhong Chung ◽  
Younghwan Kwon
Keyword(s):  
Water Content ◽  
Contact Lenses ◽  
High Water ◽  
High Water Content ◽  
Hydroxyl Groups ◽  
Silicone Hydrogel ◽  
Surface Modifier ◽  
Ethyl Methacrylate ◽  
Silicone Polymers

We introduce a hydrophilic monosaccharide-containing 2-(α-D-mannopyranosyloxy)ethyl methacrylate (ManEMA) in this study to achieve more extended and comfortable wear silicone hydrogel contact lenses by increasing water content. Molecular structure of ManEMA contains a monosaccharide moiety with four hydroxyl groups, which provide a strong interaction with water. Therefore, the ManEMA-containing hydrogels are expected to have high water content. The structure of synthesized ManEMA is confirmed by 1H and 13C NMR spectroscopy. Contact lenses containing silicone polymers are coated with a monosaccharide-containingManEMA monomer with the help of plasma treatment and the use of 3-(trimethoxylsilyl)propyl methacrylate to provide an increased hydrophilicity. The feasibility of ManEMA as a surface modifier of silicone lenses is investigated in terms of water content and surface energy.

Evaporative water loss and the role of cocoon formation in Australian frogs

1998 ◽  
Vol 46 (5) ◽  
pp. 405 ◽  
Author(s):  
Philip C. Withers
Keyword(s):  
Water Content ◽  
Water Loss ◽  
High Water ◽  
Linear Increase ◽  
Evaporative Water Loss ◽  
High Water Content ◽  
Evaporative Water ◽  
Wide Range ◽  
Very High

Measurements of evaporative water loss (EWL; mg min-1) and resistance (R; sec cm-1) for various Australian frogs indicate three general allometric patterns: non-cocooned and non-‘waterproof’ frogs with EWL ∝ Mass0.30 and R independent of body mass at about 1–3 sec cm-1, cocooned frogs with EWL reduced about 50–200-fold and R about 50–200 sec cm-1, and ‘waterproof’ frogs with EWL reduced about 5–100- fold and R about 5–100 sec cm-1. Cocooned frogs have an exponential reduction in EWL and fairly linear increase in R over time, corresponding to the temporal addition of layers to the cocoon. The biophysical properties of cocoon are generally similar for various species, although there is some variation in both resistance per thickness (5–20 × 104 s cm-2) and diffusion coefficient (0.4–2.4 × 10 –5 cm2 s-1). The hygroscopic property of frog cocoon resembles that of mammalian stratum corneum, hair and wool, and mucopolysaccharides; there is a slight increase in water content of cocoon over a wide range of humidities but a very steep increase in water content and substantial hydration and swelling at >96% RH. This extreme hygroscopic behaviour of frog cocoon at very high RH may reflect less polymer cross-linking in frog cocoon and its high digestibility. The prevention of over-hydration of frog cocoon in vivo may be attributed to the restriction of high water content to only very high RH (>96%).

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