scholarly journals Thermally reversible colloidal gels for three-dimensional chondrocyte culture

2011 ◽  
Vol 9 (67) ◽  
pp. 362-375 ◽  
Author(s):  
James W. Lapworth ◽  
Paul V. Hatton ◽  
Rebecca L. Goodchild ◽  
Stephen Rimmer
Keyword(s):  
Cell Injury ◽  
Three Dimensional ◽  
Free Cell ◽  
Solution Temperature ◽  
Colloidal Gels ◽  
Cell Recovery ◽  
Thermoresponsive Polymers ◽  
Large Numbers ◽  
Particulate Gels ◽  
Solution Behaviour

Healthy cells are required in large numbers to form a tissue-engineered construct and primary cells must therefore be increased in number in a process termed ‘expansion’. There are significant problems with existing procedures, including cell injury and an associated loss of phenotype, but three-dimensional culture has been reported to offer a solution. Reversible gels, which allow for the recovery of cells after expansion would therefore have great value in the expansion of chondrocytes for tissue engineering applications, but they have received relatively little attention to date. In this study, we examined the synthesis and use of thermoresponsive polymers that form reversible three-dimensional gels for chondrocyte cell culture. A series of polymers comprising N -isopropylacrylamide (NIPAM) and styrene was synthesized before studying their thermoresponsive solution behaviour and gelation. A poly(NIPAM-co-styrene-graft- N -vinylpyrrolidone) variant was also synthesized in order to provide increased water content. Both random- and graft-copolymers formed particulate gels above the lower critical solution temperature and, on cooling, re-dissolved to allow enzyme-free cell recovery. Chondrocytes remained viable in all of these materials for 24 days, increased in number and produced collagen type II and glycosaminoglycans.

scholarly journals Preparation and Properties of Thermoresponsive P(N-Isopropylacrylamide-co-butylacrylate) Hydrogel Materials for Smart Windows

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Jae-Hyung Park ◽  
Ji-Won Jang ◽  
Jae-Hak Sim ◽  
Il-Jin Kim ◽  
Dong-Jin Lee ◽  
...  
Keyword(s):  
Light Transmission ◽  
Crosslinking Agent ◽  
Three Dimensional ◽  
Light Transmittance ◽  
Solar Light ◽  
Solution Temperature ◽  
Smart Window ◽  
Thermoresponsive Polymers ◽  
Smart Windows ◽  
Hydrogel Films

Thermoresponsive polymers that exhibit phase transition in response to temperature change can be used as material for smart windows because they can control solar light transmission depending on the outside temperature. The development of thermoresponsive polymers for a smart window that can be used over a wide temperature range is required. Therefore, to obtain smart window materials that can be used at various temperatures, three-dimensional thermoresponsive P(NIPAm-co-BA) hydrogels were prepared by free radical polymerization from main monomer N-isopropylacrylamide, comonomer butyl acrylate, and crosslinking agent N,N′-methylenebisacrylamide (MBAm) in this study. This study examined the effect of BA content on the lower critical solution temperature (LCST) and the solar light transmittance of crosslinked P(NIPAm-co-BA) hydrogel films. The LCST of hydrogel films was found to be significantly decreased from 34.3 to 29.5°C with increasing BA content from 0 to 20 mol%. It was found that the transparent films at T=25°C (T<LCST) were converted to translucent films at a higher temperature (T=45°C) (T>LCST). These results suggested that the crosslinked P(NIPAm-co-BA) hydrogel materials prepared in this study could have high potential for application in smart window materials.

scholarly journals Thermal Behaviour of Common Thermoresponsive Polymers in Phosphate Buffer and in Its Salt Solutions

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 90
Author(s):  
Łukasz Otulakowski ◽  
Maciej Kasprów ◽  
Aleksandra Strzelecka ◽  
Andrzej Dworak ◽  
Barbara Trzebicka
Keyword(s):  
Thermal Behaviour ◽  
Phosphate Buffer ◽  
Pure Water ◽  
Thermal Response ◽  
The Body ◽  
Solution Temperature ◽  
Thermoresponsive Polymers ◽  
Aqueous Polymer ◽  
Cloud Point Temperature ◽  
Size Of Particles

Thermoresponsive polymers are a promising material for drug nanocarrier preparation, which makes the study of their aggregation in physiological conditions very important. In this paper, the thermal behaviour of the thermoresponsive polymers poly(N-isopropylacrylamide), poly(2-isopropyl-2-oxazoline-co-2-n-propyl-2-oxazoline) and poly[(2-hydroxyethyl methacrylate)-co-oligo(ethylene glycol) methyl ether methacrylate] were studied in phosphate buffer (PBS) and solutions of its salts in concentration as in PBS. The thermal response of the polymers was measured using UV-Vis and dynamic light scattering (DLS). The salts shifted the cloud point temperature (TCP) of the (co)polymers to higher values compared to the TCP of aqueous polymer solutions. In PBS and NaCl solutions, all polymers exhibited an unexpected and previously unreported transmittance profile. During heating, an additional aggregation of polymers appeared above the TCP accompanied by the formation of a precipitate. In monosodium phosphate solutions and pure water, the studied polymers showed lower critical solution temperature (LCST-type) behaviour. DLS measurements showed that a salt influenced the size of the resulting polymer particles. The sizes and stability of particles depended on the heating rate. In PBS and NaCl solutions, the size of particles in the dispersion decreased above 60 °C, and the precipitate appeared on the bottom of the cuvette. The additional aggregation of polymer and its falling out of solution may hinder the removal of carriers from the body and has to be taken into account when preparing nanocarriers.

scholarly journals Multiple-Image Encryption Algorithm Based on the 3D Permutation Model and Chaotic System

Symmetry ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 660 ◽  
Author(s):  
Xiaoqiang Zhang ◽  
Xuesong Wang
Keyword(s):  
Image Encryption ◽  
Chaotic System ◽  
Three Dimensional ◽  
Multiple Image ◽  
External Mode ◽  
Large Numbers ◽  
Permutation Model ◽  
Magic Cube ◽  
Exclusive Or ◽  
Image Encryption Algorithm

Large numbers of images are produced in many fields every day. The content security of digital images becomes an important issue for scientists and engineers. Inspired by the magic cube game, a three-dimensional (3D) permutation model is established to permute images, which includes three permutation modes, i.e., internal-row mode, internal-column mode, and external mode. To protect the image content on the Internet, a novel multiple-image encryption symmetric algorithm (block cipher) with the 3D permutation model and the chaotic system is proposed. First, the chaotic sequences and chaotic images are generated by chaotic systems. Second, the sender permutes the plain images by the 3D permutation model. Lastly, the sender performs the exclusive OR operation on permuted images. The simulation and algorithm comparisons display that the proposed algorithm possesses desirable encryption images, high security, and efficiency.

Continuum Mechanics for Coordinating Massive Microrobot Swarms

2018 ◽  
pp. 96-133
Author(s):  
Bruce J. MacLennan
Keyword(s):  
Partial Differential Equations ◽  
Continuum Mechanics ◽  
Scale Up ◽  
Three Dimensional ◽  
Fiber Bundles ◽  
Coordination Mechanisms ◽  
Embryological Development ◽  
Large Numbers ◽  
Continuous Mass ◽  
Neural Fiber

This chapter addresses the problem of coordinating the behavior of very large numbers of microrobots to assemble complex, hierarchically structured physical objects. The approach is patterned after morphogenetic processes during embryological development, in which masses of simple agents (cells) coordinate to produce complex three-dimensional structures. To ensure that the coordination mechanisms scale up to hundreds of thousands or millions of microrobots, the swarm is treated as a continuous mass using partial differential equations. A morphogenetic programming notation permits algorithms to be developed for coordinating dense masses of microrobots. The chapter presents algorithms and simulations for assembling segmented structures (artificial spines and legs) and for routing artificial neural fiber bundles. These algorithms scale over more than four orders of magnitude.

scholarly journals Specific and Nonhomologous Isofunctional Enzymes of the Genetic Information Processing Pathways as Potential Therapeutical Targets for Tritryps

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Monete Rajão Gomes ◽  
Ana Carolina Ramos Guimarães ◽  
Antonio Basílio de Miranda
Keyword(s):  
Information Processing ◽  
Genetic Information ◽  
Drug Targets ◽  
Leishmania Major ◽  
Homo Sapiens ◽  
Three Dimensional ◽  
Large Numbers ◽  
Public Data ◽  
Processing Pathways ◽  
Genetic Information Processing

Leishmania major, Trypanosoma brucei, and Trypanosoma cruzi (Tritryps) are unicellular protozoa that cause leishmaniasis, sleeping sickness and Chagas' disease, respectively. Most drugs against them were discovered through the screening of large numbers of compounds against whole parasites. Nonhomologous isofunctional enzymes (NISEs) may present good opportunities for the identification of new putative drug targets because, though sharing the same enzymatic activity, they possess different three-dimensional structures thus allowing the development of molecules against one or other isoform. From public data of the Tritryps' genomes, we reconstructed the Genetic Information Processing Pathways (GIPPs). We then used AnEnPi to look for the presence of these enzymes between Homo sapiens and Tritryps, as well as specific enzymes of the parasites. We identified three candidates (ECs 3.1.11.2 and 6.1.1.-) in these pathways that may be further studied as new therapeutic targets for drug development against these parasites.

Thermoresponsive polymers with lower critical solution temperature: from fundamental aspects and measuring techniques to recommended turbidimetry conditions

2017 ◽  
Vol 4 (2) ◽  
pp. 109-116 ◽  
Author(s):  
Qilu Zhang ◽  
Christine Weber ◽  
Ulrich S. Schubert ◽  
Richard Hoogenboom
Keyword(s):  
Lower Critical Solution Temperature ◽  
Temperature Behavior ◽  
Solution Temperature ◽  
Thermoresponsive Polymers ◽  
Critical Solution Temperature ◽  
Measuring Techniques

This focus article addresses fundamental and practical aspects of investigating polymers with lower critical solution temperature behavior.

Surface Lunar Soil Excavation Simulation Based on Three-Dimensional Discrete Element Method

2013 ◽  
Vol 376 ◽  
pp. 366-370
Author(s):  
Hui Gao ◽  
Da Wei Zhang ◽  
Bin Liu ◽  
Long Chen Duan
Keyword(s):  
Discrete Element Method ◽  
Three Dimensional ◽  
Lunar Soil ◽  
Discrete Element ◽  
Spherical Particles ◽  
Lunar Exploration ◽  
The Earth ◽  
Large Numbers ◽  
Soil Excavation ◽  
Element Method

One of the important objectives of lunar exploration is to obtain the lunar soil samples. However, the sampling process is very different from that on the Earth due to special characteristics of the lunar soil and surface environment. In order to ensure that the lunar exploration and sampling are successful, large numbers of ground experiments and computer simulations must be taken. In this paper, the surface lunar soil excavation simulation is investigated by three-dimensional discrete element method (DEM). It is implemented based on the open source LIGGGHTS, which takes the lunar soil as spherical particles. The interaction between the excavation tool and lunar soil is demonstrated. The excavation force and torque have also been calculated in real time. Moreover, the comparison of the excavation in different environments between the Earth and Moon corresponding to their different gravity accelerations was done. This paper shows that three-dimensional discrete element method can be used for the surface lunar soil excavation simulation and can provide important reference results for actual operations.

Determinants of apical membrane formation and distribution in multicellular epithelial MDCK cysts

1994 ◽  
Vol 267 (2) ◽  
pp. C473-C481 ◽  
Author(s):  
A. Z. Wang ◽  
J. C. Wang ◽  
G. K. Ojakian ◽  
W. J. Nelson
Keyword(s):  
Membrane Proteins ◽  
Cell Surface ◽  
De Novo ◽  
Apical Membrane ◽  
Three Dimensional ◽  
Collagen Gel ◽  
Free Cell ◽  
Surface Polarity ◽  
Marker Proteins ◽  
Spinner Culture

Madin-Darby canine kidney epithelial cells form three-dimensional cysts in spinner culture with a defined cell surface polarity. Transfer of cysts from spinner culture to a collagen gel matrix results in rapid loss of apical membrane proteins from the outside surface of the cyst, degradation of extracellular matrix (ECM) from the cyst lumen, and de novo formation of the apical membrane at the luminal surface. Degradation of endogenous ECM was inhibited with 1,10-phenanthroline, an inhibitor of metalloproteinases, resulting in cysts in which cells are surrounded by either cell-cell or cell-substratum contacts. The consequence of the lack of a free cell surface on the formation of a new apical membrane domain in these cysts was analyzed. Changes in cell surface polarity were followed with antibodies to marker proteins of the apical or basolateral membranes. In the absence of a free cell surface, the apical membrane formed de novo by accumulation and fusion of presorted vesicles containing apical membrane proteins; the coalescence of these vesicles results in the formation of a central lumen. These results provide novel insights into the generation of membrane domains and formation of a lumen in complex, three-dimensional epithelial structures in development.

Harmonic analysis tools for stochastic magnetohydrodynamics equations in Besov spaces

2016 ◽  
Vol 30 (28n29) ◽  
pp. 1640025 ◽  
Author(s):  
Mamadou Sango ◽  
Tesfalem Abate Tegegn
Keyword(s):  
Harmonic Analysis ◽  
Existence Result ◽  
Three Dimensional ◽  
Regularity Result ◽  
Heat Equations ◽  
Analysis Tools ◽  
Large Numbers ◽  
Magnetohydrodynamics Equation ◽  
Stochastic Heat Equations ◽  
Time Existence

We establish a regularity result for stochastic heat equations in probabilistic evolution spaces of Besov type and we use it to prove a global in time existence and uniqueness of solution to a stochastic magnetohydrodynamics equation. The existence result holds with a positive probability which can be made arbitrarily close to one. The work is carried out by blending harmonic analysis tools such as Littlewood–Paley decomposition, Jean–Micheal Bony paradifferential calculus and stochastic calculus. The law of large numbers is a key tool in our investigation. Our global existence result is new in three-dimensional spaces.

A Defence of Direct Surface Realism

Philosophy ◽  
1982 ◽  
Vol 57 (221) ◽  
pp. 339-355 ◽  
Author(s):  
Roderick Millar
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Material Objects ◽  
Sense Data ◽  
Large Numbers ◽  
The World ◽  
Physical Objects ◽  
Representative Realism ◽  
Three Dimensional Space

It is commonly believed that there are, in the world, large numbers of objects which occupy three-dimensional space. It is also commonly believed that at least a large part of people's experience is of the surfaces of these material objects. Nevertheless, arguments have been adduced in favour of the view that we are never aware of such surfaces but only of distinct items called ‘sense-data’. It has also been suggested that if we couple the view that experience is limited to sense-data with an empiricist thesis to the effect that knowledge is limited by experience then we are forced to the conclusion that we cannot have any knowledge of material objects. There have been many attempts to reconcile the sense-data thesis with common beliefs about material objects. Among them have been representative realism and phenomenalism. However, a view which may have found favour recently is the Quinean one that ‘the myth of physical objects is epistemologically superior to most in that it has proved more efficacious than other myths as a device for working a manageable structure into the flux of experience’.1

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