scholarly journals One-Dimensional Systemic Modeling of Thermal Sensors Based on Miniature Bead-Type Thermistors

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7866
Author(s):  
Rodolphe Heyd
Keyword(s):  
Thermal Properties ◽  
Thermal Characterization ◽  
Biological Tissues ◽  
System Control ◽  
Glycerol Water ◽  
Characterization Methods ◽  
One Dimensional ◽  
Bead Type

Accurate measurements of thermal properties is a major concern, for both scientists and the industry. The complexity and diversity of current and future demands (biomedical applications, HVAC, smart buildings, climate change adapted cities, etc.) require making the thermal characterization methods used in laboratory more accessible and portable, by miniaturizing, automating, and connecting them. Designing new materials with innovative thermal properties or studying the thermal properties of biological tissues often require the use of miniaturized and non-invasive sensors, capable of accurately measuring the thermal properties of small quantities of materials. In this context, miniature electro-thermal resistive sensors are particularly well suited, in both material science and biomedical instrumentation, both in vitro and in vivo. This paper presents a one-dimensional (1D) electro-thermal systemic modeling of miniature thermistor bead-type sensors. A Godunov-SPICE discretization scheme is introduced, which allows for very efficient modeling of the entire system (control and signal processing circuits, sensors, and materials to be characterized) in a single workspace. The present modeling is applied to the thermal characterization of different biocompatible liquids (glycerol, water, and glycerol–water mixtures) using a miniature bead-type thermistor. The numerical results are in very good agreement with the experimental ones, demonstrating the relevance of the present modeling. A new quasi-absolute thermal characterization method is then reported and discussed. The multi-physics modeling described in this paper could in the future greatly contribute to the development of new portable instrumental approaches.

scholarly journals State-of-the-art methods and devices for generation, exposure, and collection of aerosols from e-vapor products

2020 ◽  
Vol 4 ◽  
pp. 239784732097975
Author(s):  
Stéphanie Boué ◽  
Didier Goedertier ◽  
Julia Hoeng ◽  
Anita Iskandar ◽  
Arkadiusz K Kuczaj ◽  
...  
Keyword(s):  
Ad Hoc ◽  
State Of The Art ◽  
Physicochemical Characterization ◽  
Objective Evaluation ◽  
Vapor Generation ◽  
Characterization Methods ◽  
Clinical Exposure ◽  
Aerosol Generation

E-vapor products (EVP) have become popular alternatives for cigarette smokers who would otherwise continue to smoke. EVP research is challenging and complex, mostly because of the numerous and rapidly evolving technologies and designs as well as the multiplicity of e-liquid flavors and solvents available on the market. There is an urgent need to standardize all stages of EVP assessment, from the production of a reference product to e-vapor generation methods and from physicochemical characterization methods to nonclinical and clinical exposure studies. The objective of this review is to provide a detailed description of selected experimental setups and methods for EVP aerosol generation and collection and exposure systems for their in vitro and in vivo assessment. The focus is on the specificities of the product that constitute challenges and require development of ad hoc assessment frameworks, equipment, and methods. In so doing, this review aims to support further studies, objective evaluation, comparison, and verification of existing evidence, and, ultimately, formulation of standardized methods for testing EVPs.

Pomegranate, its Components and Modern Deliverable Formulations as Potential Botanicals in the Prevention and Treatment of Various Cancers

2021 ◽  
Vol 18 ◽  
Author(s):  
Laila Hussein ◽  
Mostafa Gouda ◽  
Harpal S. Buttar
Keyword(s):  
Side Effects ◽  
Biological Tissues ◽  
Pomegranate Juice ◽  
In Vivo Studies ◽  
Lifestyle Modifications ◽  
Cellular Mechanisms ◽  
Double Blind ◽  
Prevention And Treatment

Abstract: Cancer is a global multifactorial disease consisting of over 200 types of cancers. It is well recognized that primary prevention is an effective way to fight cancers by using natural polyphenolic anticancer foods, vegetables and fruits, avoiding exposure to carcinogenic environment, smoking cessation, and through lifestyle modifications. The present review provides up to date information on the effects and functions of pomegranate juice and its bioactive components on the most widespread six cancer types. Pomegranate contains important polyphenolic compounds such as ellagitannins and punicalagin, with strong antioxidant ability for scavenging free radicals and producing metal-chelates in the biological tissues. The in vitro and in vivo studies suggests that antioxidant and anti-inflammation properties of pomegranate constitute have major antimutagenic and antiproliferative activities for regulating gene expression, modulating cellular mechanisms, and limiting the ability of cancers to metastasize. A limited number of clinical studies have suggested that pomegranate ingredients have the potential for the prevention and treatment of cancer, especially colorectal and prostate cancer. In cancer therapy, it remains a clinical dilemma to hit the right target without inducing side effects. The costly anticancer chemotherapies are often associated with drug resistance and serious side effects in vital organs, and noncancerous neighboring cells. It appears that the pomegranate based phytotherapies would be affordable and cost-effective for next generation non-pharmacologic anticancer remedies with lesser side effects. However, well-designed, randomized, double-blind, and multi-center studies are needed to establish the long-term safety, efficacy and dose schedules for orally deliverable pomegranate formulations.

scholarly journals A 90-Day Tenofovir Reservoir Intravaginal Ring for Mucosal HIV Prophylaxis

2012 ◽  
Vol 56 (12) ◽  
pp. 6272-6283 ◽  
Author(s):  
Todd J. Johnson ◽  
Meredith R. Clark ◽  
Theodore H. Albright ◽  
Joel S. Nebeker ◽  
Anthony L. Tuitupou ◽  
...  
Keyword(s):  
Weight Percent ◽  
Control Group ◽  
Vaginal Fluid ◽  
Mechanical Stiffness ◽  
Vaginal Tissue ◽  
Glycerol Water ◽  
Intravaginal Ring ◽  
Product Effectiveness

ABSTRACTA vaginal gel containing the antiretroviral tenofovir (TFV) recently demonstrated 39% protection against HIV infection in women. We designed and evaluated a novel reservoir TFV intravaginal ring (IVR) to potentially improve product effectiveness by providing a more controlled and sustained vaginal dose to maintain cervicovaginal concentrations. Polyurethane tubing of various hydrophilicities was filled with a high-density TFV/glycerol/water semisolid paste and then end-sealed to create IVRs.In vitro, TFV release increased with polyurethane hydrophilicity, with 35 weight percent water-swelling polyurethane IVRs achieving an approximately 10-mg/day release for 90 days with mechanical stiffness similar to that of the commercially available NuvaRing. This design was evaluated in two 90-dayin vivosheep studies for TFV pharmacokinetics and safety. Overall, TFV vaginal tissue, vaginal fluid, and plasma levels were relatively time independent over the 90-day duration at approximately 104ng/g, 106ng/g, and 101ng/ml, respectively, near or exceeding the highest observed concentrations in a TFV 1% gel control group. TFV vaginal fluid concentrations were approximately 1,000-fold greater than levels shown to provide significant protection in women using the TFV 1% gel. There were no toxicological findings following placebo and TFV IVR treatment for 28 or 90 days, although slight to moderate increases in inflammatory infiltrates in the vaginal epithelia were observed in these animals compared to naïve animals. In summary, the controlled release of TFV from this reservoir IVR provided elevated sheep vaginal concentrations for 90 days to merit its further evaluation as an HIV prophylactic.

Measurement of the Optical Properties of Muscle Tissue In Vivo

2000 ◽  
Author(s):  
P. L. Kopsombut ◽  
D. Willis ◽  
A. E. Schen ◽  
L. X. Xu ◽  
X. Xu
Keyword(s):  
Optical Properties ◽  
Transport Theory ◽  
Rapid Development ◽  
Ccd Camera ◽  
High Sensitivity ◽  
Biological Tissues ◽  
In Vivo Measurement ◽  
Living Tissues

Abstract Along with rapid development of diagnostic and therapeutic applications of lasers in medicine, optical properties of various biological tissues have been extensively studied [1]. Most of the studies were performed in vitro owing to the complexity involved in in vivo measurement. To date, it is well understood that living tissue is an absorbing and scattering heterogeneous medium because of its complex structures including blood network. The transport theory cannot be readily used due to the heterogeneity and the absence of the optical properties of living tissues [2]. In this research, we have developed a procedure for measuring the total attenuation coefficient (μ1) of the exteriorized rat 2-D spinotrapezius muscle in the wavelength ranged from 480–560 nm using the collimated light from a Nitrogen-pumped dye laser and a high-sensitivity CCD camera.

Vascular Endothelial Growth Factor Inhibits the Development of Dendritic Cells and Dramatically Affects the Differentiation of Multiple Hematopoietic Lineages In Vivo

Blood ◽  
1998 ◽  
Vol 92 (11) ◽  
pp. 4150-4166 ◽  
Author(s):  
Dmitry Gabrilovich ◽  
Tadao Ishida ◽  
Tsunehiro Oyama ◽  
Sophia Ran ◽  
Vladimir Kravtsov ◽  
...  
Keyword(s):  
Stem Cells ◽  
Vascular Endothelial Growth Factor ◽  
Dendritic Cells ◽  
Growth Factor ◽  
System Control ◽  
Vascular Endothelial ◽  
Almost All ◽  
Endothelial Growth Factor

Abstract Defective function of dendritic cells (DC) in cancer has been recently described and may represent one of the mechanisms of tumor evasion from immune system control. We have previously shown in vitro that vascular endothelial growth factor (VEGF), produced by almost all tumors, is one of the tumor-derived factors responsible for the defective function of these cells. In this study, we investigated whether in vivo infusion of recombinant VEGF could reproduce the observed DC dysfunction. Continuous VEGF infusion, at rates as low as 50 ng/h (resulting in serum VEGF concentrations of 120 to 160 pg/mL), resulted in a dramatic inhibition of dendritic cell development, associated with an increase in the production of B cells and immature Gr-1+ myeloid cells. Infusion of VEGF was associated with inhibition of the activity of the transcription factor NF-κB in bone marrow progenitor cells. Experiments in vitro showed that VEGF itself, and not factors released by VEGF-activated endothelial cells, affected polypotent stem cells resulting in the observed abnormal hematopoiesis. These data suggest that VEGF, at pathologically relevant concentrations in vivo, may exert effects on pluripotent stem cells that result in blocked DC development as well as affect many other hematopoietic lineages.

scholarly journals Ni-Cu Nanoparticles and Their Feasibility for Magnetic Hyperthermia

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1988 ◽  
Author(s):  
Bianca P. Meneses-Brassea ◽  
Edgar A. Borrego ◽  
Dawn S. Blazer ◽  
Mohamed F. Sanad ◽  
Shirin Pourmiri ◽  
...  
Keyword(s):  
Magnetic Hyperthermia ◽  
Biological Tissues ◽  
Superparamagnetic Nanoparticles ◽  
Blocking Temperature ◽  
Ferromagnetic Behavior ◽  
Cytotoxicity Test ◽  
Cu Nanoparticles ◽  
Hyperthermia Treatment

Ni-Cu nanoparticles have been synthesized by reducing Ni and Cu from metal precursors using a sol–gel route followed by annealing at 300 °C for 1, 2, 3, 6, 8, and 10 h for controlled self-regulating magnetic hyperthermia applications. Particle morphology and crystal structure revealed spherical nanoparticles with a cubic structure and an average size of 50, 60, 53, 87, and 87 nm for as-made and annealed samples at 300 °C for 1, 3, 6, and 10 h, respectively. Moreover, hysteresis loops indicated ferromagnetic behavior with saturation magnetization (Ms) ranging from 13–20 emu/g at 300 K. Additionally, Zero-filed cooled and field cooled (ZFC-FC) curves revealed that each sample contains superparamagnetic nanoparticles with a blocking temperature (TB) of 196–260 K. Their potential use for magnetic hyperthermia was tested under the therapeutic limits of an alternating magnetic field. The samples exhibited a heating rate ranging from 0.1 to 1.7 °C/min and a significant dissipated heating power measured as a specific absorption rate (SAR) of 6–80 W/g. The heating curves saturated after reaching the Curie temperature (Tc), ranging from 30–61 °C within the therapeutic temperature limit. An in vitro cytotoxicity test of these Ni-Cu samples in biological tissues was performed via exposing human breast cancer MDA-MB231 cells to a gradient of concentrations of the sample with 53 nm particles (annealed at 300 °C for 3 h) and reviewing their cytotoxic effects. For low concentrations, this sample showed no toxic effects to the cells, revealing its biocompatibility to be used in the future for in vitro/in vivo magnetic hyperthermia treatment of cancer.

One Dimensional Experimental Setup to Study the Heating of Nanoparticle Laden Systems

2010 ◽  
Author(s):  
Zhenpeng Qin ◽  
John C. Bischof
Keyword(s):  
Small Volume ◽  
Laser Energy ◽  
Special Kind ◽  
Gold Nanoshells ◽  
Experimental Setup ◽  
Heat Absorption ◽  
One Dimensional ◽  
Lumped Models

Intensive efforts have been put into the use of gold nanoparticles (GNPs) for the enhancement of hyperthermia using laser in recent years since the groundbreaking work of Hirsh et al.(1) using gold nanoshells (GNS). Both in vitro (2), and in vivo (3) studies show promising results. For example, GNS, a special kind of GNP, are being manufactured and are in clinical trials (Nanospectra Bioscience, Inc). While the data is compelling, unfortunately the fundamentals of GNP heating are not entirely understood. For example, there are large discrepancies in the experimentally measured photothermal efficiency of GNPs (4, 5). Furthermore, lumped models of GNP heating in solution, by using small volume of GNP solution (4, 5), or stirring the solution (6), neglecting the variation of heat absorption throughout a system require improvement. In reality, the GNPs will attenuate the laser beam as it passes through the GNP host medium. GNPs at different locations will absorb different amount of laser energy and hence have different heat generation.

scholarly journals Preparation and Characterization of Salt-Mediated Injectable Thermosensitive Chitosan/Pectin Hydrogels for Cell Embedding and Culturing

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2674
Author(s):  
Giulia Morello ◽  
Alessandro Polini ◽  
Francesca Scalera ◽  
Riccardo Rizzo ◽  
Giuseppe Gigli ◽  
...  
Keyword(s):  
Sol Gel ◽  
Polymer Network ◽  
Cell Encapsulation ◽  
High Water ◽  
Biological Tissues ◽  
Culture Conditions ◽  
Interpenetrating Polymer Network ◽  
Sol Gel Transition

In recent years, growing attention has been directed to the development of 3D in vitro tissue models for the study of the physiopathological mechanisms behind organ functioning and diseases. Hydrogels, acting as 3D supporting architectures, allow cells to organize spatially more closely to what they physiologically experience in vivo. In this scenario, natural polymer hybrid hydrogels display marked biocompatibility and versatility, representing valid biomaterials for 3D in vitro studies. Here, thermosensitive injectable hydrogels constituted by chitosan and pectin were designed. We exploited the feature of chitosan to thermally undergo sol–gel transition upon the addition of salts, forming a compound that incorporates pectin into a semi-interpenetrating polymer network (semi-IPN). Three salt solutions were tested, namely, beta-glycerophosphate (βGP), phosphate buffer (PB) and sodium hydrogen carbonate (SHC). The hydrogel formulations (i) were injectable at room temperature, (ii) gelled at 37 °C and (iii) presented a physiological pH, suitable for cell encapsulation. Hydrogels were stable in culture conditions, were able to retain a high water amount and displayed an open and highly interconnected porosity and suitable mechanical properties, with Young’s modulus values in the range of soft biological tissues. The developed chitosan/pectin system can be successfully used as a 3D in vitro platform for studying tissue physiopathology.

Analysis of the Inverse Problem of Freezing and Thawing of a Binary Solution During Cryosurgical Processes

1995 ◽  
Vol 117 (2) ◽  
pp. 193-202 ◽  
Author(s):  
Hector Budman ◽  
Avraham Shitzer ◽  
Joshua Dayan
Keyword(s):  
Binary Solution ◽  
Biological Tissues ◽  
Integral Solution ◽  
Freezing And Thawing ◽  
Dimensional Solution ◽  
One Dimensional ◽  
Cell Destruction ◽  
Forcing Function ◽  
Warming Rate

An integral solution for a one-dimensional inverse Stefan problem is presented. Both the freezing and subsequent thawing processes are considered. The medium depicting biological tissues, is a nonideal binary solution wherein phase change occurs over a range of temperatures rather than at a single one. A constant cooling, or warming, rate is imposed at the lower temperature boundary of the freezing/thawing front. This condition is believed to be essential for maximizing cell destruction rate. The integral solution yields a temperature forcing function which is applied at the surface of the cryoprobe. An average thermal conductivity, on both sides of the freezing front, is used to improve the solution. A two-dimensional, axisymmetric finite element code is used to calculate cooling/warming rates at positions in the medium away from the axis of symmetry of the cryoprobe. It was shown that these cooling/warming rates were always lower than the prescribed rate assumed in the one-dimensional solution. Thus, similar, or even higher, cell destruction rates may be expected in the medium consistent with existing in vitro data. Certain problems associated with the control of the warming rate during the melting stage are discussed.

scholarly journals Mechanism of Oxidative Stress in Neurodegeneration

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Sonia Gandhi ◽  
Andrey Y. Abramov
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Free Radicals ◽  
Neurodegenerative Disease ◽  
Reactive Oxygen ◽  
Biological Tissues ◽  
Antioxidant Systems ◽  
Oxygen Species

Biological tissues require oxygen to meet their energetic demands. However, the consumption of oxygen also results in the generation of free radicals that may have damaging effects on cells. The brain is particularly vulnerable to the effects of reactive oxygen species due to its high demand for oxygen, and its abundance of highly peroxidisable substrates. Oxidative stress is caused by an imbalance in the redox state of the cell, either by overproduction of reactive oxygen species, or by dysfunction of the antioxidant systems. Oxidative stress has been detected in a range of neurodegenerative disease, and emerging evidence from in vitro and in vivo disease models suggests that oxidative stress may play a role in disease pathogenesis. However, the promise of antioxidants as novel therapies for neurodegenerative diseases has not been borne out in clinical studies. In this review, we critically assess the hypothesis that oxidative stress is a crucial player in common neurodegenerative disease and discuss the source of free radicals in such diseases. Furthermore, we examine the issues surrounding the failure to translate this hypothesis into an effective clinical treatment.

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