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Littérature scientifique sur le sujet « Concentration cell »

Auteur : Grafiati

Publié le 9 mars 2023

Mis à jour le 10 mars 2023

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Articles de revues sur le sujet "Concentration cell"

Kusuma, Riska Anggri, Linda Suyati et Wasino Hadi Rahmanto. « Effect of Lactose Concentration as Lactobacillus bulgaricus Substrate on Potential Cells Produced in Microbial Fuel Cell Systems ». Jurnal Kimia Sains dan Aplikasi 21, n^o 3 (31 juillet 2018) : 144–48. http://dx.doi.org/10.14710/jksa.21.3.144-148.

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The effect of laxose concentration as Lactobacillus bulgaricus bacterial substrate on the cell potential produced in Microbial Fuel Cell System has been done. This study aims to determine the effect of lactose concentration as bacterial substrate, to generate electricity, maximum electric potential and determine the potential value of standard lactose (E ° Lactose.) Based on Nernst equation. The MFC system of two compartments and bridges of salt as a linkage is used in this study. Anode contains lactose with variation of concentration 3 - 7% and bacteria. The cathode contains a 1M KMO4. The electrodes used are graphite. MFC operational time is 14 days. The results showed that the lactose concentration had an effect on the cell potential produced in the MFC system. Maximum cell potential yielded at 4% lactose concentration, that is 710 mV then based on Nerst equation theory obtained E ° Lactose value in MFC system of + 0,236 V.

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Kisitu, Jaffar. « Chemical concentrations in cell culture compartments (C5) – concentration definitions ». ALTEX 36, n^o 1 (2019) : 154–60. http://dx.doi.org/10.14573/altex.1901031.

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Z, Ding. « Concentration Polarization of Ox-LDL and Its Effect on Cell Proliferation and Apoptosis in Human Endothelial Cells ». Journal of Cardiology and Cardiovascular Medicine 1, n^o 1 (2016) : 011–18. http://dx.doi.org/10.29328/journal.jccm.1001003.

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Kamath, Meghana, Isaac Houston, Alexander Janovski, Xiang Zhu, Sivakumar Gowrisankar, Anil Jegga et Rodney DeKoter. « Myeloid Gene Activation and T Cell/Natural Killer Cell Gene Repression in Cells Expressing Two Distinct PU.1 Concentrations. » Blood 110, n^o 11 (16 novembre 2007) : 1242. http://dx.doi.org/10.1182/blood.v110.11.1242.1242.

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Abstract The Ets transcription factor PU.1 (encoded by the gene Sfpi1) functions in a concentration-dependent manner as a hematopoietic cell fate determinant. PU.1 levels are uniform in early hematopoiesis, increase during myeloid differentiation, and decrease after erythrocyte and T cell/natural killer cell commitment. It is unknown how downstream target genes respond to changes in PU.1 concentration. To address this, we generated mice with two distinct hypomorphic alleles of Sfpi1 and analyzed interleukin-3 dependent cell lines from fetal liver cells homozygous for either allele. PU.1 was produced in these cells at ∼20% (Sfpi1BN/BN) or ∼2% (Sfpi1Blac/Blac) of wild type. These cells fail to terminally differentiate as a consequence of low PU.1 expression and can be maintained as cell lines. To determine what groups of genes are expressed in response to two distinct PU.1 concentrations, we performed whole-genome microarray analysis and compared gene expression in Sfpi1BN/BN and Sfpi1Blac/Blac cell lines to Sfpi1−/− cell lines. Groups of downstream target genes were activated or repressed in four modes in response to the two discrete concentrations of PU.1: at higher but not lower PU.1 concentration, at lower but not higher PU.1 concentration, at both lower and higher concentration, and in a gradient fashion. We decided to focus on genes regulated in a gradient manner, because dose-dependency suggests that these may be direct targets of PU.1. Genes activated in a gradient manner were mostly myeloid-specific and enriched for target genes of PU.1. Genes repressed in a gradient manner included erythroid-specific genes and, unexpectedly, T cell and natural killer cell-specific genes. T cell genes were also repressed by PU.1 in cultured progenitor-B cells. With this unique allelic system, we can study three discrete concentrations of PU.1 at 20%, 2%, and 0% to examine concentration-dependent effects of PU.1 on target genes and lineage decisions. Overall, our results suggest that PU.1 functions in a concentration-dependent manner to promote myeloid differentiation and repress T cell or natural killer cell development.

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Kočí, Vladimír, Darek Dragoun et Jaromír Lukavský. « Determination of algal cell culture (Desmodesmus subspicatus) concentration using a microplate reader ». Algological Studies/Archiv für Hydrobiologie, Supplement Volumes 122 (1 décembre 2006) : 123–35. http://dx.doi.org/10.1127/1864-1318/2006/0122-0123.

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Rowley, SD, WI Bensinger, TA Gooley et CD Buckner. « Effect of cell concentration on bone marrow and peripheral blood stem cell cryopreservation ». Blood 83, n^o 9 (1 mai 1994) : 2731–36. http://dx.doi.org/10.1182/blood.v83.9.2731.2731.

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Abstract The effects of cell concentration during cryopreservation on bone marrow (BM) or peripheral blood (PB)-derived hematopoietic progenitor cells have not been described. The much greater numbers of cells harvested for autologous PB stem cell (PBSC) transplantation requires that the cells be frozen at higher cell concentrations, or in much greater volumes, compared with BM. We cryopreserved 108 PBSC collections from 30 patients at an average (+/- SD) cell concentration of 3.7 +/- 1.9 x 10(8) nucleated cells per mL in 127 +/- 45 mL. The proportion of mononuclear cells was 52.9% +/- 27.2%. The products also contained 2.9 +/- 2.1 x 10(9) platelets/mL and an average red cell proportion of 12.9% +/- 7.2%. The nucleated cell recovery after thawing was 75.4% +/- 13.0%. The nucleated cell concentration during freezing was not predictive for the postthaw recoveries of nucleated cells (P = .38), granulocyte-macrophage colony-forming unit (P = .06) or CD34+ cells (P = .54), or for the viability of mononuclear cells (P = .81). The platelet and red cell concentrations similarly were not predictive for these endpoints. Samples (3 BM, 7 PBSC) from 10 patients were simultaneously cryopreserved at two-fold, and from 5 additional patients (PBSC) at 6- to 24-fold differing cell concentrations. A lower recovery of erythroid burst forming unit was found for samples frozen at higher cell concentrations (P = .04), but no significant differences were found in the other endpoints listed above. The average cell concentration during freezing for each patient's PBSC collections (n = 34 patients) did not predict time to achieve a PB count of > 500 granulocytes/microL (P = .51) or platelet transfusion independence (P = .39). Patients achieved these endpoints of engraftment at medians of 12 and 13 days, respectively. The infusion of these products was generally well tolerated. Similarly, the cell concentration at which BM cells were frozen did not predict for the duration of granulocyte (P = .63) or platelet (P = .36) aplasias for 54 patients undergoing autologous BM transplantation. These data suggest that PBSC or BM cells collected for transplantation may be cryopreserved at very high cell concentrations without loss of engraftment potential or undue infusion-related toxicity.

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The effects of cell concentration during cryopreservation on bone marrow (BM) or peripheral blood (PB)-derived hematopoietic progenitor cells have not been described. The much greater numbers of cells harvested for autologous PB stem cell (PBSC) transplantation requires that the cells be frozen at higher cell concentrations, or in much greater volumes, compared with BM. We cryopreserved 108 PBSC collections from 30 patients at an average (+/- SD) cell concentration of 3.7 +/- 1.9 x 10(8) nucleated cells per mL in 127 +/- 45 mL. The proportion of mononuclear cells was 52.9% +/- 27.2%. The products also contained 2.9 +/- 2.1 x 10(9) platelets/mL and an average red cell proportion of 12.9% +/- 7.2%. The nucleated cell recovery after thawing was 75.4% +/- 13.0%. The nucleated cell concentration during freezing was not predictive for the postthaw recoveries of nucleated cells (P = .38), granulocyte-macrophage colony-forming unit (P = .06) or CD34+ cells (P = .54), or for the viability of mononuclear cells (P = .81). The platelet and red cell concentrations similarly were not predictive for these endpoints. Samples (3 BM, 7 PBSC) from 10 patients were simultaneously cryopreserved at two-fold, and from 5 additional patients (PBSC) at 6- to 24-fold differing cell concentrations. A lower recovery of erythroid burst forming unit was found for samples frozen at higher cell concentrations (P = .04), but no significant differences were found in the other endpoints listed above. The average cell concentration during freezing for each patient's PBSC collections (n = 34 patients) did not predict time to achieve a PB count of > 500 granulocytes/microL (P = .51) or platelet transfusion independence (P = .39). Patients achieved these endpoints of engraftment at medians of 12 and 13 days, respectively. The infusion of these products was generally well tolerated. Similarly, the cell concentration at which BM cells were frozen did not predict for the duration of granulocyte (P = .63) or platelet (P = .36) aplasias for 54 patients undergoing autologous BM transplantation. These data suggest that PBSC or BM cells collected for transplantation may be cryopreserved at very high cell concentrations without loss of engraftment potential or undue infusion-related toxicity.

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Gülden, M., S. Mörchel et H. Seibert. « Factors influencing nominal effective concentrations of chemical compounds in vitro : cell concentration ». Toxicology in Vitro 15, n^o 3 (juin 2001) : 233–43. http://dx.doi.org/10.1016/s0887-2333(01)00008-x.

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Trifilio, Steven M., Paul R. Yarnold, Marc H. Scheetz, Judy Pi, Gennethel Pennick et Jayesh Mehta. « Serial Plasma Voriconazole Concentrations after Allogeneic Hematopoietic Stem Cell Transplantation ». Antimicrobial Agents and Chemotherapy 53, n^o 5 (17 février 2009) : 1793–96. http://dx.doi.org/10.1128/aac.01316-08.

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ABSTRACT Plasma voriconazole concentrations vary considerably between patients receiving standard dosing, and trough voriconazole concentrations are known to affect efficacy and toxicity. Temporal variations in serial plasma voriconazole concentrations through the course of therapy in hematopoietic stem cell transplantation patients has not been carefully described. Paired voriconazole concentrations in 64 patients were studied to determine the predictability of the second concentration based on the first. The difference between the two values was ≤5% in six patients. In 25 patients, the second concentration was higher by a median of 40%. In 33 patients, the subsequent concentration was lower by a median of 59%. For patients with an initial concentration of <2 μg/ml, the correlation between the two values was poor (r = 0.24; P < 0.17). For those with an initial concentration of ≥2 μg/ml, the correlation was good (r = 0.72; P < 0.0001). There was no relationship between the magnitude of the change and the time elapsing between the two measurements. Among the 43 patients who had an initial concentration of ≥1 μg/ml, the two voriconazole measurements were strongly correlated (r = 0.66, P < 0.0001), but only 67% had a voriconazole serum concentration of ≥1 μg/ml on the second measurement. No studied variables were reliable predictors in identifying concentrations above or below 1 or 2 μg/ml. Our data suggest that variations in voriconazole concentrations are unpredictable despite standard dosing, and the acceptability of a concentration on one occasion cannot be extrapolated to future concentrations in the same patient. This suggests that ongoing therapeutic drug monitoring and dose adjustment may be beneficial in patients requiring prolonged voriconazole therapy.

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Jia, Chen, Abhyudai Singh et Ramon Grima. « Concentration fluctuations in growing and dividing cells : Insights into the emergence of concentration homeostasis ». PLOS Computational Biology 18, n^o 10 (4 octobre 2022) : e1010574. http://dx.doi.org/10.1371/journal.pcbi.1010574.

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Intracellular reaction rates depend on concentrations and hence their levels are often regulated. However classical models of stochastic gene expression lack a cell size description and cannot be used to predict noise in concentrations. Here, we construct a model of gene product dynamics that includes a description of cell growth, cell division, size-dependent gene expression, gene dosage compensation, and size control mechanisms that can vary with the cell cycle phase. We obtain expressions for the approximate distributions and power spectra of concentration fluctuations which lead to insight into the emergence of concentration homeostasis. We find that (i) the conditions necessary to suppress cell division-induced concentration oscillations are difficult to achieve; (ii) mRNA concentration and number distributions can have different number of modes; (iii) two-layer size control strategies such as sizer-timer or adder-timer are ideal because they maintain constant mean concentrations whilst minimising concentration noise; (iv) accurate concentration homeostasis requires a fine tuning of dosage compensation, replication timing, and size-dependent gene expression; (v) deviations from perfect concentration homeostasis show up as deviations of the concentration distribution from a gamma distribution. Some of these predictions are confirmed using data for E. coli, fission yeast, and budding yeast.

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Thèses sur le sujet "Concentration cell"

Sarkar, Aniruddh. « Microfluidic concentration-enhanced single cell enzyme activity assay ». Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/79325.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references.
Cells sense stimuli, process information and respond using signaling networks regulated by enzymatic activity of various proteins. Aberrations in signaling are associated with diseases such as cancer. Most current methods lack the sensitivity to measure enzymatic activity in single cells and instead measure the average of large cell populations. Cellular heterogeneity, overlooked in these methods, is widespread and relevant. Microfabricated tools are uniquely suited to single cell analysis due to the match in size scale which enables high sensitivity, high throughput measurements. In this thesis we develop a microfluidic platform for the direct measurement of enzyme activities from selected single cells without disrupting their extracellular context. We develop modules to: enhance enzyme assay sensitivity by microfluidic confinement, interface microfluidic devices with selected single cells, enable multiplexing and then integrate these modules to perform single cell assays. We first investigate electrokinetic trapping of charged biomolecules in a nanofluidic concentrator for enhancing enzyme assay sensitivity by simultaneously accumulating enzyme and substrate into a reaction plug. Non-linear enhancement of reaction kinetics in this device is predicted by a mathematical model and experimentally verified. A linear enhancement mode is developed where only the enzyme is accumulated and is reacted with substrate later in an enclosed volume defined by integrated pneumatic valves or by micro-droplets formed using an integrated droplet generator. This device is then used to perform high-throughput measurement of secreted cellular proteases. We then develop a nicrofluidic probe for lysis and capture of the contents of selected single adherent cells from standard tissue culture platforms by creating a small lysis zone at its tip using hydrodynamic confinement. The single cell lysate is then divided and mixed with different substrates and confined in small chambers for fluorimetric assays. An integrated nanofluidic concentrator enables further concentration-enhancement. We demonstrate the ability to measure, from selected single cells, the activity of kinases: Akt, MAPKAPK2, PKA and a metabolic enzyme, GAPDH - separately or simultaneously. This assay platform can correlate single cell phenotype or extracellular context to intracellular biochemical state. We present preliminary explorations of the correlation of cell morphology or local cell population density to kinase activity.
by Aniruddh Sarkar.
Ph.D.

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Haas, Kathleen. « Modeling Blood Cell Concentration in a Dialysis Cartridge ». Digital WPI, 2010. https://digitalcommons.wpi.edu/etd-theses/425.

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Healthy kidneys are able to filter toxins from one's blood and remove excess fluid from one's body. Kidney dialysis is a process that performs the work of kidneys that cannot function normally. During the process of hemodialysis, blood from the patient's body is run through a dialysis cartridge through very thin hollow fibers made of a semi- permeable membrane. Waste and water travel from the blood, through the pores of the membrane, and into a fluid called dialysate. We attempt to model the velocities and pressures of blood plasma and dialysate in a dialysis cartridge, as well as to model the concentration of blood cells. We find that varying the pressure in the dialysate moves the location at which the maximum blood cell concentration occurs. We also find that the maximum blood cell concentration is directly proportional to the product of the blood cell Peclet number and the permeability of the membrane.

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Andrews, Arcadio Garcia de Castro. « Growth inhibitors and promoters from high concentration animal cell cultures ». Thesis, University of Surrey, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259568.

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Bajpayee, Anurag. « Concentration of Cryoprotectant in water-in-oil microdroplets for single cell vitrificaton ». Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/46055.

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Includes bibliographical references (leaves 50-51).
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.
"September 2008."
(cont.) Droplets with an initial concentration of IM were found to be concentrated to about 3-4M in 90s while droplets starting at 2M were concentrated to 6M in about the same time. The entire process takes place over a time scale of about one minute, fast enough to minimize exposure times but slow enough to be precisely controllable. This phenomenon is demonstrated to dynamically concentrate cryoprotectants within single cell-containing droplets. These droplets of sizes of about 30 micron diameter were concentrated to 3-4M from a starting concentration of IM in about 300s. The cells are tolerant to this concentration process and do not die when subjected to it. The process may be used in practice to innocuously concentrate cell encapsulating droplets which may then be vitrified before they are exposed to high temperatures for fatally long time scales. With appropriate characterization, the controllability of the process will allow for choosing exact cryoprotectant concentration levels used for vitrification. The demonstrated phenomenon has several other applications in cryobiology. Its controllability and speed may be used to dynamically modulate cryoprotectant concentrations in preservation protocols that require stepwise concentration or dilution. In addition, the process was found to be reversible and may thus be used for unloading cryoprotectants by controlled cooling as opposed to heating.
Among the several challenges associated with vitrification of cells, a major roadblock is the requirement of high concentrations of cryoprotectant chemicals and the damages caused by exposure of cells to these high concentrations at physiological temperatures. It is thus desirable to minimize the time of exposure of cells with high concentrations of cryoprotectants to physiological temperatures. In addition, vitrification requires very rapid cooling rates. As cooling rates of a sample are limited by its size, it becomes ideal to use the minimum sizes of the sample to be preserved. Certain organic oils, such as soybean oil, are made of triacylglycerols and are capable of dissolving small amounts of water due to the presence of ester groups, a property which enhances significantly with increasing temperature. This phenomenon was exploited to accomplish temperature controlled concentration of cryoprotectants in single water droplets with and without cells dispersed in the organic phase. The organic phase used in the present work is soybean oil while glycerol is used as the cryoprotectant. Glycerol was found to be comparatively insoluble in soybean oil at 35 'C for up to 10 minutes. The present work employed heating on a temperature controlling stage and temperature increases of about 10K. Solutions of glycerol in DI Water were mixed with soybean oil and emulsions made by vigorous agitation. The water to oil concentration was kept at 0.1% v/v to simulate an infinite dissolution medium and to prevent different droplets from affecting each other. To prevent premature dissolution, the oil is saturated with water at room temperature by incubating for 48 hours. Micro-liter-sized droplets of the emulsion are placed on a heating/ cooling stage and droplets of 15-20 micron diameter are visually selected from polydisperse emulsion for observation under a microscope. Upon increasing temperature, water dissolves into the oil rendering the droplet highly concentrated with the oil-insoluble cryoprotectant. The experiment involved heating to 35 °C from room temperature, so that all water eventually dissolved into the oil.
by Anurag Bajpayee.
S.M.

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Barrett, E., et Phillip R. Scheuerman. « The Effect of Cell Inoculum Level and Substrate Concentration on p- cresol Degradation ». Digital Commons @ East Tennessee State University, 1998. https://dc.etsu.edu/etsu-works/2914.

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Norcio, Lawrence P. « Effects of microcarrier concentration, agitation rate, and serum concentration on the specific growth rate of mouse L cells in batch cultures ». Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179949129.

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McQuinn, Chris. « Design of a mechanical device for fabricating protein concentration gradients to study cell adhesion ». Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18728.

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The binding interaction between specialized proteins within the extracellular matrix (ECM) and specific membrane receptors in cells are pivotal for regulating cell adhesion and migration. Current methods used to generate patterned ECM substrates for the study of migration involve technically complicated devices that are expensive and demand specialized training. Some are also not applicable to the microscopic scale relevant for cells or provide inadequate substrates for growing sensitive cells such as neurons. This Masters thesis introduces an effective method to pattern proteins with micron scale precision at a reasonable financial cost and requires minimal training. The method is based on a device called the squeegee that uses a PDMS (polydimethyl siloxane) barrier to precisely control exposure of protein from solution onto specific areas of a glass surface to regulate adsorption time. The patterns may be produced with a range of proteins on a multitude of glass surfaces. The squeegee method recreated an ECM in the form of graded protein patterns, including continuous gradients and stepped gradients. Mammalian epithelial cells (CHO-K1) were cultured on a surface comprised of a fibronectin stepped gradient and shown to increase in cell spreading with increasing fibronectin surface density. Other proteins were successfully pattered including netrin-1, an important guidance cue in the developing mammalian spinal cord.
L'interaction entre les protéines spécialisées qui sont dans la matrice extracellulaire (MEC) et les récepteurs à la limite de la membrane d'un organisme cellulaire est essentielle à la migration des cellules. Les méthodes actuelles pour étudier la migration impliquent l'utilisation d'appareils techniquement complexes, dispendieux et requérant une formation spécifique. De plus, ces méthodes ne sont pas applicables à l'échelle microscopique des organismes cellulaires ou sont inadéquates pour cultiver des cellules spécialisées. Ce mémoire de maîtrise introduit une méthode ayant un faible rapport coût-efficacité pour modeler les protéines avec une précision micrométrique et qui requiert peu de connaissances techniques. Il est possible de produire ces modèles avec une gamme de protéines et sur une multitude de surfaces de verre. La base de cette méthode est un appareil qui est nommé « la racle » qui utilise une barrière de polydimethyl siloxane (PDMS) pour contrôler précisément l'adsorption de protéine d'une solution sur une surface de verre. La méthode qui utilise la racle a permis de recréer des MEC sous forme de gradients de protéines, comprenant aussi bien des pentes continues que des marches d'escalier. Des cellules épithéliales de mammifères (CHO-K1) ont été cultivées sur une surface ayant un gradient de fibronectine en marche d'escalier, les cellules ont montré une augmentation dans leur étalement proportionnelle à la densité de surface de fibronectine.

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Gordon, Christopher, et res cand@acu edu au. « Hydrostatic and thermal influences on intravascular volume determination during immersion : quantification of the f-cell ratio ». Australian Catholic University. School of Exercise Science, 2001. http://dlibrary.acu.edu.au/digitaltheses/public/adt-acuvp4.14072005.

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Previous data have shown that the most prevalent, indirect plasma volume (PV) measurement technique, which utilises changes in haematocrit (Hct) and haemoglobin concentration ([Hb]), underestimates actual PV changes during immersion, when compared to a direct tracer-dilution method. An increase in the F-cell ratio (whole-body haematocrit (Hctw) to large-vessel haematocrit (Hctv) ratio) has been purported as a possible explanation, probably due to hydrostatic and thermally-mediated changes during water immersion. Previous investigators have not quantified the F-cell ratio during immersion. Therefore, this study sought to determine the effect of the F-cell ratio on the indirect method during both, thermoneutral and cold-water immersions. Seven healthy males were tested three times, seated upright in air (control: 21.2°C SD ±1.1), and during thermoneutral (34.5oC SD ±0.2) and cold-water immersion (18.6oC SD ±0.2), immersed to the third intercostal space for 60 min. Measurements during the immersion tests included PV (Evans blue dye column elution, Evans blue dye computer programme, and Hct [Hb]), red cell volume (RCV; sodium radiochromate), cardiac frequency (fc) and rectal temperature (Tre). Plasma volume during the control trial remained stable, and equivalent across the three tests. There was a hydrostatically-induced increase in PV during thermoneutral immersion, when determined by the Evans blue dye method (16.2%). However, the Hct/[Hb] calculation did not adequately reflect this change, and underestimated the relative PV change by 43%. In contrast, PV decreased during cold immersion when determined using the Evans blue dye method by 17.9% and the Hct/[Hb] calculation by 8.0%, respectively, representing a 52% underestimation by the latter method. There was a non-significant decline in RCV during both immersions. Furthermore, an increase (8.6%) and decrease (-14.4%) in blood volume (BV) was observed during thermoneutral and cold-water immersions, respectively. The decline in RCV during thermoneutral immersion attenuated the BV expansion. Despite the disparity between the PV methods, there was no increase in the F-cell ratio during either immersion. In contrast, there was a significant decline in the F-cell ratio during the control: air and thermoneutral immersion, which may indicate that other, undefined variables may impact on the stability of the red cell compartment. The current study is the first to show that the Hct/[Hb] method clearly underestimates PV changes during both thermoneutral and cold-water immersion. Furthermore, RCV was shown, for the first time, to decline during both immersions. However, the changes in the F-cell ratio during this study, did not account for the underestimation of PV change using the Hct/[Hb] method.

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Tunggal, Jonathan Kurniadi. « Cell concentration and drug penetration, implications for the reversal of multidrug resistance in solid tumours ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0017/NQ45743.pdf.

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Chornewich, Cristina. « Bacterial transport in granular porous media : the effects of cell concentration and media pre-coating ». Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=67039.

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Column transport experiments were conducted under saturated conditions to examine the effects of cell concentration and media pre-coating. Two strains of E. coli were used in the study; the commonly studied laboratory organism E. coli K12 D21 and a mutant of the waterborne pathogen E. coli O157:H7. Column experiments were conducted with both clean sand and sand that was pre-coated with bacteria. The influent concentration of the E. coli strains was varied over several orders of magnitude to examine the effect of cell concentration. Concentration dependent removal rates were observed for both organisms in both the clean and media pre-coated sand columns. It was also found that the media pre-coating either does not influence the transport behavior or it decreases the attachment efficiency. Although differences in transport are observed, these differences are not large enough to have a significant influence on the predicted travel distances.
Des expériences de transport par colonne ont été menées afin d'examiner les effets de la concentration des cellules et du pré-revêtement de média. Deux souches de bactéries ont été utilisées: E. coli K12 D12 et une souche mutante E. coli O157:H7. Les expériences par colonne ont été menées avec du sable propre et du sable qui a été préalablement enduit de bactéries. La concentration de l'influent en bactérie a été variée sur plusieurs ordres de grandeur pour examiner l'effet de la concentration cellulaire. Une dépendance du taux d'élimination à la concentration a été observée pour les deux souches de bactéries dans les deux types de sable. De plus, le pré-revêtement de média n'influence d'aucune façon le comportement du transport ni en réduit l'efficacité d'adhésion. Bien que des différences dans le transport ont été observées, celles-ci n'ont eu aucun effet significatif sur la prédiction de la distance à parcourir.

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Livres sur le sujet "Concentration cell"

Stocks, Stuart Michael. The flocculation of high concentration cell debris from E.coli. Birmingham : University of Birmingham, 1997.

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Tonkaboni, Madjid Mohseni. The influence of cell concentration and morphology on yielding properties of filamentous fermentation broths. Ottawa : National Library of Canada, 1994.

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S, Aronson Peter, dir. Na⁺-H⁺ exchange, intracellular pH, and cell function. Orlando : Academic Press, 1986.

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Komhyr, W. D. Operations handbook--ozone measurements to 40-km altitude with model 4A electrochemical concentration cell (ECC) ozonesondes (used with 1680-MHz radiosondes). Silver Spring, Md : U.S. Dept. of Commerce, National Oceanic and Atmospheric Administration, Environmental Research Laboratories, Air Resources Laboratory, 1986.

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Chapitres de livres sur le sujet "Concentration cell"

Gooch, Jan W. « Concentration Cell ». Dans Encyclopedic Dictionary of Polymers, 163–64. New York, NY : Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_2787.

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Büntemeyer, Heino, Sonja Siwiora et Jürgen Lehmann. « Inhibitors of Cell Growth : Accumulation and Concentration ». Dans Animal Cell Technology, 651–55. Dordrecht : Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-5404-8_102.

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Reardon, Kenneth F., et Thomas H. Scheper. « Determination of Cell Concentration and Characterization of Cells ». Dans Biotechnology, 179–223. Weinheim, Germany : Wiley-VCH Verlag GmbH, 2008. http://dx.doi.org/10.1002/9783527620852.ch6.

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Wijnsma, R., R. Verpoorte, P. A. A. Harkes, F. van Iren et H. J. G. ten Hoopen. « Conditioning of Media : An Elaborate Method of Optimizing Initial Growth Hormone Concentration ». Dans Plant Cell Biotechnology, 297–303. Berlin, Heidelberg : Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-73157-0_30.

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Maruhashi, Fumio, Sei Murakami et Kenji Baba. « Automated monitoring of cell concentration and viability using an image analysis system ». Dans Cell Culture Engineering IV, 281–89. Dordrecht : Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-0257-5_31.

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Young, David B. « Vascular Cell Responses to Changes in Potassium Concentration ». Dans Basic Science for the Cardiologist, 71–86. Boston, MA : Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-1443-5_5.

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Ciaccheri, L., A. G. Mignani, A. A. Mencaglia et L. Giannelli. « Static Light Scattering for Measuring Biological Cell Concentration ». Dans Lecture Notes in Electrical Engineering, 219–23. Boston, MA : Springer US, 2011. http://dx.doi.org/10.1007/978-1-4614-0935-9_37.

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Ludowise, Michael, et Lewis Fraas. « High-Concentration Cassegrainian Solar Cell Modules and Arrays ». Dans Solar Cells and their Applications, 337–60. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2010. http://dx.doi.org/10.1002/9780470636886.ch15.

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Moreira, J. L., P. E. Cruz, P. C. Santana et M. J. T. Carrondo. « BHK Aggregate Sedimentation : Cell Concentration and Downstream Processing ». Dans Animal Cell Technology : Developments Towards the 21st Century, 799–803. Dordrecht : Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0437-1_127.

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Romein, B., A. K. Shrivastava, C. Hellinga, J. P. Van Dijken et K. C. H. A. M. Luyben. « Control of Cell Concentration in Fedbatch Hybridoma Cultures ». Dans Animal Cell Technology : Developments Towards the 21st Century, 851–54. Dordrecht : Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0437-1_136.

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Actes de conférences sur le sujet "Concentration cell"

Selimović, Šeila, Woo Young Sim, Sang Bok Kim, Yun Ho Jang, Won Gu Lee, Masoud Khabiry, Hojae Bae, Sachin Jambovane, Jong Wook Hong et Ali Khademhosseini. « Exponential Concentration Gradients in Microfluidic Devices for Cell Studies ». Dans ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-53529.

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Microscale technologies are a powerful tool in many biological and chemical applications, as they utilize only small reagent volumes. Microfluidics is especially well compatible with biological materials and applications, for example protein crystallization, high throughput assay analysis, and various cell studies. In that context, non-linear gradients of particles and molecules as well as efficient mixing of the components inside the lab-on-a-chip are crucial for many experimental studies: testing of and analyzing biological responses to different analyte concentration levels, studying the native cell microenvironment or cellular responses during different growth and proliferation stages. Thus, a microfluidic approach that allows for generation of different concentration gradients and specifically exponential gradients emerges as a helpful technology, and is also compatible with cells.

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Mohan, Sujith, et S. O. Bade Shrestha. « Evaluation of the Performance Characteristics and Modeling of an Alkaline Fuel Cell ». Dans ASME 2009 7th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2009. http://dx.doi.org/10.1115/fuelcell2009-85158.

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Alkaline fuel cells are one of the low cost types of fuel cells. In this contribution, the performance of an alkaline fuel cell was investigated by varying different operational parameters. The cell was tested under four different electrolyte concentrations and three different levels of anode flow rates. The results of the test revealed that the efficiency of the cell increases with the increase in electrolyte concentration. Anode flow rate was not found to have a considerable impact on the cell performance. Impedance spectroscopy has been conducted to validate the mathematical model and further investigate ohmic resistance, anode and cathode activation losses and mass transport losses. The optimal level of electrolyte concentration and anode flow rate for an alkaline fuel cell has been deduced through modeling & statistical analysis.

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Wang, Weiping, Chengxian Guan, Zhongqing Chen et Lingxiang Huang. « HF-NQO-100 model oxygen concentration cell ». Dans International Conference on Sensors and Control Techniques (ICSC2000), sous la direction de Desheng Jiang et Anbo Wang. SPIE, 2000. http://dx.doi.org/10.1117/12.385596.

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Khan, Iftekhar, et Gary Rosengarten. « Simulation of an electrowetting solar concentration cell ». Dans SPIE Optics + Photonics for Sustainable Energy, sous la direction de Adam P. Plesniak et Andru J. Prescod. SPIE, 2015. http://dx.doi.org/10.1117/12.2186904.

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Gray, Allison, Robert Boehm et Kenneth W. Stone. « Modeling a Passive Cooling System for Photovoltaic Cells Under Concentration ». Dans ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ht2007-32693.

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Cooling of photovoltaic cells under high intensity solar irradiance is a major concern when designing concentrating photovoltaic systems. The cell temperature will increase if the waste heat is not removed and the cell voltage/power will decrease with increasing cell temperature. This paper presents an analysis of the passive cooling system on the Amonix high concentration photovoltaic system (HCPV). The concentrator geometry is described. A model of the HCPV passive cooling system was made using Gambit. Assumptions are discussed that were made to create the numerical model based on the actual system, the methods for drawing the model is discussed, and images of the model are shown. Fluent was used to compute the numerical results. In addition to the theoretical results that were computed, measurements were made on a system in the field. These data are compared to the theoretical data and differences are calculated. Theoretical conditions that were studied included uniform cell temperatures and worst case weather scenarios, i.e., no wind, high ambient conditions, and high solar irradiance. The performance of the Amonix high concentrating system could be improved if more waste heat were removed from the cell. Now that a theoretical model has been developed and verified, it will be used to investigate different designs and material for increasing the cooling of the system.

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Amontree, Jacob, Kangfu Chen, Jose Varillas et Z. Hugh Fan. « Capillary Force Driven Single-Cell Spiking Apparatus for Studying Circulating Tumor Cells ». Dans ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-87109.

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The characterization of single cells within heterogeneous populations has great impact on both biomedical sciences and cancer research. By investigating cellular compositions on a broad scale, pertinent outliers may be lost in the sample set. Alternatively, an investigation focused on the behavior of specific cells, such as circulating tumor cells (CTCs), will reveal genetic biomarkers or phenotypic characteristics associated with cancer and metastasis. On average, CTC concentration in peripheral blood is extremely low, as few as one to two per billion of healthy blood cells. Consequently, the critical element lacking in many methods of CTC detection is accurate cell capture efficiency at low concentrations. To simulate CTC isolation, researchers usually spike small amounts of tumor cells to healthy blood for separation. However, spiking tumor cells at extremely low concentrations is challenging in a standard laboratory setting. We report our study on an innovative apparatus and method designed for low-cost, precise, and replicable single-cell spiking (SCS). Our SCS method operates solely from capillary aspiration without the reliance on external laboratory equipment. To ensure that our method does not affect the viability of each cell, we investigated the effects of surface membrane tensions induced by aspiration. Finally, we performed affinity-based CTC isolation using human acute lymphoblastic leukemia cells (CCRF-CEM) spiked into healthy whole blood with the SCS technique. The results of the isolation experiments demonstrate the reliability of our method in generating low-concentration cell samples.

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Diaz, Gerardo C., Roland Winston, Alexander Ritschel, Sergio Pineda et Pablo Benitez. « Analysis of Natural Convection Coupled With Thermal Radiation in Novel High-Concentration Nonimaging-Optics-Based System for Multi-Junction Solar Cells ». Dans ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14178.

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The design of solar concentrators based on nonimaging optics provides an inexpensive, but highly powerful concentrating system with large angular tolerance and uniform cell illumination. However, multi-junction tandem-cell-based concentrators require high levels of concentration to become cost effective. The two-mirror design is capable of working at an average concentration over 800 suns with local concentrations below 2000 suns without a homogenizing kaleidoscope. With this level of concentration it is essential to analyze the thermal effects of the unit at different operating conditions. In this paper we analyze the coupled effects of natural convection and surface thermal radiation inside the air-filled enclosure formed by the primary mirror and the cover of the concentrator that holds the secondary mirror. A coordinate transformation is applied to the governing equations to generate a mapping from a parabolic domain to a rectangular domain. The results show an increase in the total Nusselt number with a decrease in the maximum temperature of the secondary mirror.

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Xu, Heqi, Changxue Xu et Zhengyi Zhang. « Sedimentation Study of Bioink Containing Living Cells ». Dans ASME 2019 14th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/msec2019-2747.

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Abstract 3D bioprinting has more and more applications in tissue engineering, in vitro drug testing, and regenerative medicine. The bioink consisting of the biocompatible polymer (as extracellular matrix) and the living cells is the starting material. Because the typical bioprinting process may take several hours, the suspended cells in the bioink sediment with time, which significantly affects the bioink stability as well as the following bioprinting quality and reliability. The cell sedimentation is determined by the integral effects of drag force and buoyancy and gravity. The gravitational force is related to the cells, and the drag force and buoyant force is related to the polymer concentration. This paper is the first paper to quantify the cell sedimentation process of the bioink within 0.5% and 1% (w/v) polymer concentrations respectively. The cell sedimentation phenomenon has been observed using the bioink within 0.5% and 1% (w/v) polymer concentrations. The cell sedimentation velocity has been estimated to be 1.18 μm/s with the polymer concentrations to be 0.5% (w/v) and 0.88 μm/s for the bioink with the polymer concentrations to be 1% (w/v). It is also found that the cell concentration increases significantly at the bottom of the bioink reservoir, resulting in cell aggregates due to cell-cell interaction.

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Chen, Ming, Heather Michaud, Michael L. Lovett, David L. Kaplan et Sankha Bhowmick. « Role of Nanofibrous Scaffold Geometry in Cellular Adhesion ». Dans ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-192946.

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The goal of this study was to investigate the kinetics of NIH 3T3 fibroblast cell adhesion and their actin cytoskeleton organization on different geometry electrospun polycaprolactone nanofibrous scaffolds. Cell adhesion kinetics was measured by MTS assay. Cells on beaded scaffolds, which are not uniform fibrous scaffolds, showed the lowest adhesion rate and the smallest cytoskeleoton organization in all experiments. For uniform fiber scaffolds, cell adhesion rate was a function of scaffold specific surface area (SSA). Cell adhesion rate increased with increasing SSA when scaffold SSA was higher than 7.13 μm−1. Cell adhesion in high serum concentration culture medium was higher than in low serum concentration medium for all scaffolds. Results indicate that from 0–5% serum concentrations, cell adhesion at 4 or 8 hours were not significantly different between different geometry scaffolds. F-actin maximum projected area was quantified to indicate mature cell adhesion. Results indicate higher area for cells cultured in high serum concentration medium on 18.79 μm−1 (SSA) scaffolds, and had higher values when cultured for 8 hrs compared to 24 hrs. 10% serum concentration and 18.79 μm−1 (SSA) scaffolds are considered to be an optimum combination for enhanced cell adhesion.

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Liu, Fan, Pawan K. C., Ge Zhang et Jiang Zhe. « Target Cell Detection via Microfluidic Magnetic Beads Assay ». Dans ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65088.

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We present a novel cell detection device based on a magnetic bead cell assay and microfluidic Coulter counting technology. The device can detect specific target cells ratios, as well as cells size distribution and concentrations. The device consists of two identical micro Coulter counters separated by a fluid chamber where an external magnetic field is applied. Target cells conjugated with magnetic beads are retarded by the magnetic field; transit time of a target cell passing through the second counter is longer than that through the first counter. In comparison, a non-target cell transit through two counters with nearly the same time. We demonstrated the transit time delay increased approximately linearly with the increasing target cell concentration. The limit of detection (LOD) of the assay was estimated to be 5.6% in terms of target cell ratio.

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Rapports d'organisations sur le sujet "Concentration cell"

Kuhne, Wendy, Candace Langan, Lucas Angelette et Lesleyann Hawthorne. Deuterium Concentration Effects on Cell Cycle Progression. Office of Scientific and Technical Information (OSTI), août 2020. http://dx.doi.org/10.2172/1651107.

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KUHNE, WENDY, et LUCAS ANGELETTE. DEUTERIUM CONCENTRATION EFFECTS ON CELL CYCLE PROGRESSION. Office of Scientific and Technical Information (OSTI), octobre 2021. http://dx.doi.org/10.2172/1827682.

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KUHNE, WENDY. DEUTERIUM CONCENTRATION EFFECTS ON CELL CYCLE PROGRESSION. Office of Scientific and Technical Information (OSTI), octobre 2021. http://dx.doi.org/10.2172/1827952.

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Block, David L., et Ahmad Sleiti. Bachelor of Science-Engineering Technology Program and Fuel Cell Education Program Concentration. Office of Scientific and Technical Information (OSTI), septembre 2011. http://dx.doi.org/10.2172/1166983.

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Cushing, Donish, Darshana Goakar et Bomi Joseph. Higher bioactivity cannabidiol in greater concentration more greatly reduces valvular interstitial cell calcification. Peak Health Center, septembre 2018. http://dx.doi.org/10.31013/2001f.

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Wally, Karl. Micropower chemical fuel-to-electric conversion : a "regenerative flip" hydrogen concentration cell promising near carnot efficiency. Office of Scientific and Technical Information (OSTI), mai 2006. http://dx.doi.org/10.2172/966250.

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Barnard, M. R., H. Macgregor, A. D. Michelson et C. R. Valeri. Effects of White Cell Filtration, ACD Concentration and Rotation During Collection, Storage and Cryopreservation of Platelet Concentrates. Fort Belvoir, VA : Defense Technical Information Center, mai 1997. http://dx.doi.org/10.21236/ada360226.

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Moran, Nava, Richard Crain et Wolf-Dieter Reiter. Regulation by Light of Plant Potassium Uptake through K Channels : Biochemical, Physiological and Biophysical Study. United States Department of Agriculture, septembre 1995. http://dx.doi.org/10.32747/1995.7571356.bard.

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The swelling of plant motor cells is regulated by various signals with almost unknown mediators. One of the obligatory steps in the signaling cascade is the activation of K+-influx channels -K+ channels activated by hyperpolarization (KH channels). We thus explored the regulation of these channels in our model system, motor cell protoplasts from Samanea saman, using patch-clamp in the "whole cell" configuration. (a) The most novel finding was that the activity of KH channels in situ varied with the time of the day, in positive correlation with cell swelling: in Extensor cells KH channels were active in the earlier part of the day, while in Flexor cells only during the later part of the day; (b) High internal pH promoted the activity of these channels in Extensor cells, opposite to the behavior of the equivalent channels in guard cells, but in conformity with the predicted behavior of the putative KH channel, cloned from S. saman recently; (c) HIgh external K+ concentration increased (KH channel currents in Flexor cells. BL depolarized the Flexor cells, as detected in cell-attached patch-clamp recording, using KD channels (the K+-efflux channels) as "voltage-sensing devices". Subsequent Red-Light (RL) pulse followed by Darkness, hyperpolarized the cell. We attribute these changes to the inhibition of the H+-pump by BL and its reactivation by RL, as they were abolished by an H+-pump inhibitor. BL increased also the activity KD channels, in a voltage-independent manner - in all probability by an independent signaling pathway. Blue-Light (BL), which stimulates shrinking of Flexor cells, evoked the IP3 signaling cascade (detected directly by IP3 binding assay), known to mobilize cytosolic Ca2+. Nevertheless, cytosolic Ca2+ . did not activate the KD channel in excised, inside-out patches. In this study we established a close functional similarity of the KD channels between Flexor and Extensior cells. Thus the differences in their responses must stem from different links to signaling in both cell types.

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OJI, LAWRENCE, et SAVIDRA LUCATERO. CHARACTERIZATION OF INFREQUENT SAMPLES FROM THE CONCENTRATION, STORAGE, AND TRANSFER FACILITY : LEAK DETECTION BOX (LDB) DRAIN CELL SAMPLE LIMS# 20195. Office of Scientific and Technical Information (OSTI), novembre 2020. http://dx.doi.org/10.2172/1734664.

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DEKARSKE, JOHN. CHARACTERIZATION OF INFREQUENT SAMPLES FROM THE CONCENTRATION, STORAGE, AND TRANSFER FACILITY : LEAK DETECTION BOX (LDB) DRAIN CELL SAMPLE : AUGUST 04, 2022SAMPLE. Office of Scientific and Technical Information (OSTI), septembre 2022. http://dx.doi.org/10.2172/1889236.

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