Bibliographies thématiques / PDMS surface

Littérature scientifique sur le sujet « PDMS surface »

Auteur : Grafiati
Publié le 10 mars 2023

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Articles de revues sur le sujet "PDMS surface"

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Akiyama, Yoshikatsu, Masayuki Yamato et Teruo Okano. « Preparation of Poly(N-isopropylacrylamide) Grafted Polydimethylsiloxane by Using Electron Beam Irradiation ». Journal of Robotics and Mechatronics 25, no 4 (20 août 2013) : 631–36. http://dx.doi.org/10.20965/jrm.2013.p0631.

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A poly(N-isopropylacrylamide) (PIPAAm) grafted poly(dimethylsiloxane) (PDMS) surface was prepared as a temperature-responsive cell culture surface by using electron beam (EB) irradiation. Different chemical treatments to modify the bare PDMS surface were investigated for subsequent grafting of PIPAAm, and treatment conditions were optimized to prepare the temperature-responsive cell culture surface. The PDMS surface was initially activated to form silanol groups with conventional O2 plasma or hydrochloric acid (HCl) treatment. Activated PDMS surfaces were individually immobilized with three different conventional silane compounds, i.e., 3-mercaptopropyltrimethoxysilane (MerTMS), 3-methacryloxypropyltrimethoxysilane (MetTMS), and 3-aminopropyltrimethoxysilane (AmiTMS). O2 plasma treatment made PDMS more hydrophilic. In contrast, PDMS surfaces activated with HCl treatment were relatively hydrophobic. Observation of the activated PDMS surface modified with MerTMS, MetTMS, and AmiTMS indicated that these silane compounds had been favorably immobilized on plasma-treated PDMS surfaces. FT-IR/ATR analysis demonstrated that immobilized silane compounds enabled PIPAAm grafting on the PDMS surface. Cell attachment and detachment analysis also suggested that the PDMS surface sequentially treated with O2 plasma and AmiTMS compound was a substrate appropriate for preparing a temperature-responsive cell culture surface by EB irradiation-induced PIPAAm grafting method. The intelligent surface may further be applied to mechanically stretchable temperature-responsive cell culture surfaces.
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Kemkemer, Ralf, Zhang Zenghao, Yang Linxiao, Kiriaki Athanasopulu, Kerstin Frey, Zhishan Cui, Haijia Su et Liu Luo. « Surface modification of Polydimethylsiloxane by hydrogels for microfluidic applications ». Current Directions in Biomedical Engineering 5, no 1 (1 septembre 2019) : 93–96. http://dx.doi.org/10.1515/cdbme-2019-0024.

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AbstractIn vitro, hydrogel-based ECMs for functionalizing surfaces of various material have played an essential role in mimicking native tissue matrix. Polydimethylsiloxane (PDMS) is widely used to build microfluidic or organ-on-chip devices compatible with cells due to its easy handling in cast replication. Despite such advantages, the limitation of PDMS is its hydrophobic surface property. To improve wettability of PDMS-based devices, alginate, a naturally derived polysaccharide, was covalently bound to the PDMS surface. This alginate then crosslinked further hydrogel onto the PDMS surface in desired layer thickness. Hydrogel-modified PDMS was used for coating a topography chip system and in vitro investigation of cell growth on the surfaces. Moreover, such hydrophilic hydrogel-coated PDMS is utilized in a microfluidic device to prevent unspecific absorption of organic solutions. Hence, in both exemplary studies, PDMS surface properties were modified leading to improved devices.
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Wang, Bin, J. Hugh Horton et Richard D. Oleschuk. « Sulfonated-polydimethylsiloxane (PDMS) microdevices with enhanced electroosmotic pumping and stability ». Canadian Journal of Chemistry 84, no 4 (1 avril 2006) : 720–29. http://dx.doi.org/10.1139/v06-044.

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Polydimethylsiloxane (PDMS) microfluidic devices offer several advantages in terms of cost and ease of fabrication compared with those fabricated from both glass and silicon materials. PDMS, however, has some potential disadvantages compared with other materials including high hydrophobicity, which makes filling the micron-sized channels difficult, and minimal surface charge resulting in reduced electroosmotic flow (EOF). Here, we describe the oxidation of the PDMS surface to form silanol groups using both air plasma and a discharge from a Tesla coil, and subsequent modification to form sulfonated-PDMS surfaces. The flow performance of freshly prepared and aged sulfonated-PDMS chips was determined at pH 5 and compared with those of unmodified and oxidized PDMS chips. The electroosmotic mobility (µeo) for a sulfonated-PDMS microdevice was determined at various pH values (pH 3~8) and compared with that for an oxidized PDMS chip. The lower pKa of a sulfonic acid modified surface compared with a silanol modified surface generated a stronger EOF over the entire pH range studied. Chemical force titrations were used to characterize the changes in functional groups present on the surface of freshly prepared and aged sulfonated-PDMS surfaces. These experiments show that the sulfonated-PDMS is a superior material for use in microfluidic applications because (i) it supports EOF over a much wider range of pH than similar polymer materials and (ii) is less susceptible to degradation of its EOF rate owing to air aging effects and surface reorganization.Key words: polydimethylsiloxane (PDMS), sulfonated surface modification, electroosmotic flow (EOF), aging effect, chemical force titrations.
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Lopera, S., et R. D. Mansano. « Plasma-Based Surface Modification of Polydimethylsiloxane for PDMS-PDMS Molding ». ISRN Polymer Science 2012 (3 avril 2012) : 1–5. http://dx.doi.org/10.5402/2012/767151.

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We present and compare two processes for plasma-based surface modification of Polydimethylsiloxane (PDMS) to achieve the antisticking behavior needed for PDMS-PDMS molding. The studied processes were oxygen plasma activation for vapor phase silanization and plasma polymerization with tetrafluoromethane/hydrogen mixtures under different processing conditions. We analyzed topography changes of the treated surfaces by atomic force microscopy and contact angle measurements. Plasma treatment were conducted in a parallel plate reactive ion etching reactor at a pressure of 300 mTorr, 30 Watts of RF power and a total flow rate of 30 sccm of a gas mixture. We found for both processes that short, low power, treatments are better to create long-term modifications of the chemistry of the polymer surface while longer processes or thicker films tend to degrade faster with the use leaving rough surfaces with higher adherence to the molded material.
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Azizipour, Neda, Rahi Avazpour, Mohamad Sawan, Abdellah Ajji et Derek H. Rosenzweig. « Surface Optimization and Design Adaptation toward Spheroid Formation On-Chip ». Sensors 22, no 9 (21 avril 2022) : 3191. http://dx.doi.org/10.3390/s22093191.

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Spheroids have become an essential tool in preclinical cancer research. The uniformity of spheroids is a critical parameter in drug test results. Spheroids form by self-assembly of cells. Hence, the control of homogeneity of spheroids in terms of size, shape, and density is challenging. We developed surface-optimized polydimethylsiloxane (PDMS) biochip platforms for uniform spheroid formation on-chip. These biochips were surface modified with 10% bovine serum albumin (BSA) to effectively suppress cell adhesion on the PDMS surface. These surface-optimized platforms facilitate cell self-aggregations to produce homogenous non-scaffold-based spheroids. We produced uniform spheroids on these biochips using six different established human cell lines and a co-culture model. Here, we observe that the concentration of the BSA is important in blocking cell adhesion to the PDMS surfaces. Biochips treated with 3% BSA demonstrated cell repellent properties similar to the bare PDMS surfaces. This work highlights the importance of surface modification on spheroid production on PDMS-based microfluidic devices.
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Swart, Morne, et Peter E. Mallon. « Hydrophobicity recovery of corona-modified superhydrophobic surfaces produced by the electrospinning of poly(methyl methacrylate)-graft-poly(dimethylsiloxane) hybrid copolymers ». Pure and Applied Chemistry 81, no 3 (1 janvier 2009) : 495–511. http://dx.doi.org/10.1351/pac-con-08-08-15.

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Superhydrophobicity is dependent on both the surface energy and the texture of the surface. These factors are discussed in terms of a series of electrospun poly(methyl methacrylate)-graft-poly(dimethylsiloxane) (PMMA-g-PDMS) copolymers with different poly(dimethylsiloxane) (PDMS) content. These copolymers are synthesized via conventional free radical copolymerization of methyl methacrylate (MMA) and monomethacryloxypropyl-terminated PDMS macromonomers. It is shown how these copolymers can be electrospun to produce copolymer fibers with diameters in the 100-1000 nm range. The effect of the copolymer composition (and hence the surface energy) and the electrospinning tip-to-collector distance (TCD) on the fiber morphology is discussed. The surfaces produced by the electrospinning process show superhydrophobic properties where the preferential surface segregation of the PDMS component is combined with the roughness of the fiber surface. The surface energy of the fibers is varied by variation of the PDMS content in the copolymers as well as by post-spinning modification with corona discharge. The hydrophobicity of the surfaces shows a greater dependence on the PDMS content than on the average fiber diameter. After exposure of these fiber surfaces to corona discharge, the initial superhydrophobic surfaces become easily wettable despite the fact that much of the surface roughness is maintained after exposure. The samples show the phenomena of hydrophobocity recovery after corona exposure. The rate and extent of this recovery depends on the PDMS content and the corona exposure time. Despite the recovery, scanning electron microscopy (SEM), swelling measurements, and confocal Raman spectroscopy show that permanent surface changes have taken place. The surfaces do not recover to their original superhydrophobic state.
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Ramlan, Nadiah, Saiful Irwan Zubairi et Mohamad Yusof Maskat. « Response Surface Optimisation of Polydimethylsiloxane (PDMS) on Borosilicate Glass and Stainless Steel (SS316) to Increase Hydrophobicity ». Molecules 27, no 11 (25 mai 2022) : 3388. http://dx.doi.org/10.3390/molecules27113388.

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Particle deposition on the surface of a drying chamber is the main drawback in the spray drying process, reducing product recovery and affecting the quality of the product. In view of this, the potential application of chemical surface modification to produce a hydrophobic surface that reduces the powder adhesion (biofouling) on the wall of the drying chamber is investigated in this study. A hydrophobic polydimethylsiloxane (PDMS) solution was used in the vertical dipping method at room temperature to determine the optimum coating parameters on borosilicate glass and stainless steel substrates, which were used to mimic the wall surface of the drying chamber, to achieve highly hydrophobic surfaces. A single-factor experiment was used to define the range of the PDMS concentration and treatment duration using the Response Surface Methodology (RSM). The Central Composite Rotatable Design (CCRD) was used to study the effects of the concentration of the PDMS solution (X1, %) and the treatment duration (X2, h) on the contact angle of the substrates (°), which reflected the hydrophobicity of the surface. A three-dimensional response surface was constructed to examine the influence of the PDMS concentration and treatment duration on contact angle readings, which serve as an indicator of the surface’s hydrophobic characteristics. Based on the optimisation study, the PDMS coating for the borosilicate glass achieved an optimum contact angle of 99.33° through the combination of a PDMS concentration of X1 = 1% (w/v) and treatment time of X2 = 4.94 h, while the PDMS coating for the stainless steel substrate achieved an optimum contact angle of 98.31° with a PDMS concentration of X1 = 1% (w/v) and treatment time of X2 = 1 h. Additionally, the infrared spectra identified several new peaks that appeared on the PDMS-treated surfaces, which represented the presence of Si-O-Si, Si-CH3, CH2, and CH3 functional groups for the substrates coated with PDMS. Furthermore, the surface morphology analysis using the Field Emission Scanning Electron Microscopy (FESEM) showed the presence of significant roughness and a uniform nanostructure on the surface of the PDMS-treated substrates, which indicates the reduction in wettability and the potential effect of unwanted biofouling on the spray drying chamber. The application of PDMS and PTFE on the optimally coated substrates successfully reduced the amount of full cream milk particles that adhered to the surface. The low surface energy of the treated surface (19–27 mJ/m2) and the slightly higher surface tension of the full cream milk (54–59 mJ/m2) resulted in a high contact angle (102–103°) and reduced the adhesion work on the treated substrates (41–46 mJ/m2) as compared to the native substrates.
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Shi, Dongyan, Dan Ma, Feiqing Dong, Chen Zong, Liyue Liu, Dan Shen, Wenji Yuan, Xiangmin Tong, Hengwu Chen et Jinfu Wang. « Proliferation and multi-differentiation potentials of human mesenchymal stem cells on thermoresponsive PDMS surfaces grafted with PNIPAAm ». Bioscience Reports 30, no 3 (15 décembre 2009) : 149–58. http://dx.doi.org/10.1042/bsr20090026.

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The thermo-responsivity of PNIPAAm [poly(N-isopropylcarylamide)]-grafted PDMS [poly(dimethylsiloxane)] surface is a property that could be feasibly used for detaching cells adhered on the surface. We used benzophenone-initiated photopolymerization to graft PNIPAAm on PDMS substrates to construct the PNIPAAm-grafted PDMS surface and this PDMS surface was highly thermo-responsive. hMSCs (human mesenchymal stem cells) were used to analyse the proliferation and multi-differentiation of stem cells on the PNIPAAm-grafted PDMS surface. The results showed that hMSCs could adhere on the PNIPAAm-grafted PDMS surface at 37°C and form cell colonies, and then become fibroblastic. The proliferation potential of hMSCs on the PNIPAAm-grafted PDMS surface was not significantly different from that on a plate surface coated with gelatin. However, as it proved easier to detach cells from the surface, by changing temperature, a higher viability of detached cells could be obtained with the PNIPAAm-grafted PDMS surface, using a temperature shift, compared with a gelatin-coated surface, where cells are detached by treatment with trypsin. hMSCs on the PNIPAAm-grafted PDMS surface were induced into osteoblasts, adipocytes and neurocytes under osteogenic medium, adipogenic medium and neurogenic medium respectively. The PNIPAAm-grafted PDMS surface was favourable for osteogenesis of hMSCs, although the potentials of adipogenesis and neurogenesis of hMSCs on the PNIPAAm-grafted PDMS surface were similar to those on the plate surface coated with gelatin. The above results demonstrate that the PNIPAAm-grafted PDMS surface not only kept the potentials of proliferation and multi-differentiation of hMSCs, but also increased the viability of hMSCs.
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Protsak, Iryna S., Yevhenii M. Morozov, Dong Zhang et Volodymyr M. Gun’ko. « Surface Chemistry of Nanohybrids with Fumed Silica Functionalized by Polydimethylsiloxane/Dimethyl Carbonate Studied Using 1H, 13C, and 29Si Solid-State NMR Spectroscopy ». Molecules 26, no 19 (1 octobre 2021) : 5974. http://dx.doi.org/10.3390/molecules26195974.

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The investigation of molecular interactions between a silica surface and organic/inorganic polymers is crucial for deeper understanding of the dominant mechanisms of surface functionalization. In this work, attachment of various depolymerized polydimethylsiloxanes (PDMS) of different chain lengths, affected by dimethyl carbonate (DMC), to silica nanoparticles pretreated at different temperatures has been studied using 29Si, 1H, and 13C solid-state NMR spectroscopy. The results show that grafting of different modifier blends onto a preheated silica surface depends strongly on the specific surface area (SSA) linked to the silica nanoparticle size distributions affecting all textural characteristics. The pretreatment at 400 °C results in a greater degree of the modification of (i) A-150 (SSA = 150 m2/g) by PDMS-10/DMC and PDMS-1000/DMC blends; (ii) A-200 by PDMS-10/DMC and PDMS-100/DMC blends; and (iii) A-300 by PDMS-100/DMC and PDMS-1000/DMC blends. The spectral features observed using solid-state NMR spectroscopy suggest that the main surface products of the reactions of various depolymerized PDMS with pretreated nanosilica particles are the (CH3)3SiO-[(CH3)2SiO-]x fragments. The reactions occur with the siloxane bond breakage by DMC and replacing surface hydroxyls. Changes in the chemical shifts and line widths, as shown by solid-state NMR, provide novel information on the whole structure of functionalized nanosilica particles. This study highlights the major role of solid-state NMR spectroscopy for comprehensive characterization of functionalized solid surfaces.
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Lin, Wei-Chih, et Nur Mohd Razali. « Temporary Wettability Tuning of PCL/PDMS Micro Pattern Using the Plasma Treatments ». Materials 12, no 4 (20 février 2019) : 644. http://dx.doi.org/10.3390/ma12040644.

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Surface wettability plays an important role in determining the function of a wound dressing. Dressings with hydrophobic surfaces are suitable for bacterial adsorption, however, a hydrophilic surface is needed to improve cell attachment for most anchorage-dependent cell types. Furthermore, the hydrophobicity/hydrophilicity of the surface can be used to direct cellular processes such as cell initial attachment, adhesion, and migration during wound healing. Thus, a surface with an ability to switch their surface wettability improves the practicality of the dressing. In this study, we propose a temporary surface wettability tuning for surface patterning utilizing plasma treatment. Polycaprolactone (PCL) and polydimethylsiloxane (PDMS) surfaces were treated with tetrafluoromethane (CF4), sulphur hexafluoride (SF6), and oxygen (O2) plasma, and the effects on the surface wettability, roughness, and chemical composition were investigated. Based on the contact angle measurement, CF4 plasma altered surface wettability of PCL and PDMS films to hydrophobic and hydrophilic, respectively. After CF4 treatment, better attachment of primary mouse embryonic fibroblast cell (3T3) was observed on the treated PDMS surface. Embedding PCL into PDMS generated a hydrophobic-hydrophilic pattern mixture surface, which offers great potential in the tissue engineering field such as cell patterning and guidance.
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Thèses sur le sujet "PDMS surface"

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Essö, Carola. « Modifying Polydimethylsiloxane (PDMS) surfaces ». Thesis, Mälardalen University, Department of Biology and Chemical Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-491.

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The aim of the project was to modify polydimethylsiloxane (PDMS) surfaces in order to minimize adsorption of proteins. PDMS is used in micro-fluidic devices that control the delivery of samples to a sensor chip in Biacore instrumentation. These instruments are used to characterize interactions between biomolecules with a detection principle based on surface plasmon resonance (SPR). To minimize adsorption of proteins poly-ethylene-oxide (PEO) based surfactants, were added to the buffer. The added PEO surfactants were P20, Pluronic F-127 and Brij 35. Interaction of these surfactants with the sensor chip in Biacore instruments was also examined. Creating a more hydrophilic surface layer on PDMS by oxidation was also examined.

When surfactants were continuously added to protein samples, as in dynamically coating of PDMS surfaces, Brij 35 resulted in the strongest reduction in protein adsorption. Brij 35 was also the surfactant that was easiest to remove from both PDMS and the sensor surfaces. Pluronic bound strongest to surfaces, and is most suitable when only adding surfactant to the buffer in a pre-coating step. All surfactants did reduce protein adsorption considerably (99% or more) and addition is necessary when working with protein solutions and hydrophobic surfaces as PDMS. Another alternative is oxidation of PDMS surface, which is an easy procedure that decreased the protein adsorption to about 10% compared to adsorption to untreated surface.

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Thorslund, Sara. « Microfluidics in Surface Modified PDMS : Towards Miniaturized Diagnostic Tools ». Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7270.

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Wang, Xin C. « Surface wettability studies of PDMS using flame plasma treatment ». Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/54483.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 30).
The flame plasma treatment studied in this thesis was able to oxidize the surface of Polydimethylsiloxane (PDMS) in a fraction of a second. It was found to be a much faster way to modify PDMS surface wettability than the current technologies. The surface wettability of Polydimethylsiloxane (PDMS) treated with flame plasma was studied. The surface wettability was characterized by contact angle measurements using water and a surface tension liquid as the probe liquids. Two experimental parameters were varied in this investigation: a) distance from the PDMS surface to the inner flame cone; b) the dwell time of the PDMS under the flame. The study concluded that the same surface wettability can be achieved through different combinations of distance and dwell time. The shortest dwell time needed to induce a contact angle of 100 or less on the treated PDMS surface in this experimental setup was approximately 0.18 second. This study also found that over treatment of the PDMS surface in the flame plasma yielded a reversal treatment effect and decreased the surface wettability. The flame plasma yielded uniform contact angle measurements within 15% across the PDMS surface. The recovery mechanism in the treated PDMS surfaces was dominated by the diffusion of untreated polymers from the bulk PDMS to the treated surface. The results from this investigation demonstrated the potential for the flame plasma treatment to be used in rapid manufacturing of PDMS microfludic devices.
by Xin C. Wang.
S.B.
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Khorasani, Mohammad Taghi. « Laser induced surface modifications of PDMS as a bio-compatible material ». Thesis, Brunel University, 1997. http://bura.brunel.ac.uk/handle/2438/5206.

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Surface modification of polydimethylsiloxane (PDMS) based vulcanizate rubber by C02-pulsed laser as the excitation source, without a photosensitizer, was studied at room temperature. The modified surfaces were characterized using a variety of techniques including scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDXA), attenuated total reflectance infrared (ATR-IR) spectroscopy and water drop contact angle analysis. EDXA showed that all of the treated PDMS surfaces contained a higher ratio of O/Si than the base PDMS. SEM micrographs and water drop contact angle variations showed the uniform porosity and high decrease in the wettability of the surface of PDMS respectively. The bulk mechanical properties of PDMS after laser-treatment did not change, as shown by dynamic mechanical thermal analysis (DMTA). The friction coefficient of the surface of the modified silicone decreased drastically, even after only one pulse was delivered to it. Data from in vitro blood compatibility experiments indicated a significant reduction of platelet adhesion and aggregation for the modified surfaces and those platelets which were adherent remained unspread (no activation). The extent of reduction of platelet adhesion was correlated to the number of laser pulses. The attachment of anchorage dependent cells, namely Baby Hamster Kidney (BILK) fibroblastic cells was investigated under stationary culture conditions. The laser treated surfaces showed little adhesion, no spreading and growth properties. This technique can be employed to prepare PDMS samples in which one surface is laser treated and the other is untreated. Such materials may be useful in, for example, medical implants in which one (the treated) surface is in contact with a blood supply and hence does not cause cell aggregation (clotting) and the other side is tissue compatible (allows adhesion of tissue). Acrylamide (AAm), 2-hydroxyethylmethacrylate (HEMA) and hydroxyethylmethacrylate phosphatidyl choline (HEMAPC) were grafted onto preirradiated PDMS. Platelet adhesion and cell attachment studies show that the biocompatibility of the AAm and HEMA grafted PDMS are intermediate between that of untreated PDMS and either the HEMAPC grafted PDMS surface, or PDMS surfaces that had been treated with 10 CO. laser pulses.
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Rizvi, Syed Ali Shabi. « Water and radiation induced surface changes in PDMS and amino acid adsorption ». Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548789.

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Forster, Simon. « Surface modification of PDMS-based microfluidic devices through plasma polymerisation : production and application ». Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531221.

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Banerjee, Markus K. « Acoustic wave interactions with viscous liquids spreading in the acoustic path of a surface acoustic wave sensor ». Thesis, Nottingham Trent University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302521.

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Olander, Björn. « Silicone biomaterials obtained by plasma treatment and subsequent surface hydrosilylation ». Doctoral thesis, KTH, Fibre and Polymer Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3698.

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The need for safe and functional implants has led to anincreased demand for improved biomaterials. The performance invivo depends on the interaction between the biologicalsurrounding and the surface of the material. By tailoring thesurface of a material with suitable bulk properties,biomaterials with an ability to interact with the biologicalsystem in a specific and controlled way are obtained. Siliconeelastomers have been used as biomaterials for several decades,but it is widely recognized that they are difficult to modifyby the conventional methods used for organic polymers due tothe partly inorganic structure of silicone.

This thesis presents a strategy to obtain siliconebiomaterials by covalent coupling of molecules to the surfaceusing silicon chemistry. The first step is to introduce Si-Hgroups onto the surface of silicone elastomers by plasmatreatment. The second step is to react a terminal double bondof a molecule with the formed Si-H group by a catalyzedhydrosilylation reaction. The coupled molecule may eitherprovide the desired properties itself, or have a functionalitythat is able to couple another molecule with suitablecharacteristics.

The influence of plasma treatment in hydrogen, argon andoxygen on the silicone elastomer was characterized by X-rayphotoelectron spectroscopy (XPS). To quantify the effect ofplasma treatment, the method of ternary XPS diagrams wasdeveloped. It was found that undesired silica-like layers wereformed under severe treatment conditions. Argon plasma at lowpower and short treatment time was the most suitable parametersetting. Subsequent hydrosilylation grafting ofallyltetrafluoroethylether, aminopropylvinylether andN-vinylformamide showed that it was possible to functionalizethe surface via a covalent link to the surface. The primaryamino groups introduced onto the surface were accessible forfurther coupling reactions. Heparin surfaces were obtained by acoupling reaction with the introduced amino groups.

Keywords:Silicone elastomers, PDMS, XPS, ESCA, surfacemodification, plasma

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Apaydin, Elif. « Microfabrication Techniques for Printing on PDMS Elastomers for Antenna and Biomedical Applications ». The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1253138931.

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Qin, Yubo. « Developing a Poly(Dimethylsiloxane) (PDMS)/SU-8 (Negative Photoresist) Hybrid Microfluidic System for Sensitive Detection of Circulating Tumour Cells ». Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37892.

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Cancer is the second leading cause of death in the world. It is therefore critically important to detect cancer in its early stage to significantly increase the survival rate of cancer patients. Circulating tumour cells (CTCs) are cancer cells that peel off from primary tumour and enter bloodstream in early stage of a cancer, and thus it has been established that these CTCs are reliable targets for early cancer diagnosis. However, background signal reduction and optimization of CTC capturing mechanisms are still significant challenges in CTC detections with high sensitivities and accuracies. To this end, we have developed an aptamers and dendrimers based ultra non-fouling microfluidic detection system for sensitive detections of circulating tumour cells. More specifically, we demonstrate a simple strategy to bind PDMS and SU-8 surfaces in order to prepare a hybrid microfluidic device and subsequently modify both surfaces simultaneously using poly(amidoamine) (PAMAM), a highly hydrophilic dendrimer to improve non-fouling properties of the hybrid microfluidic channel. The resulting hybrid microfluidic system shows a remarkable non-specific adsorption suppression of 99.7% when tested with hydrophobic microbead suspension, an ultra non-fouling performance that has not been reported before. This is significantly important for detections with high sensitivities. X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and water contact angle are used to characterize and confirm surface modifications. In addition, we investigate the combined effects of surface properties on surface non-fouling performance to both live and dead cells. (3-aminopropyl)-trimethoxysilane (APTMS), carboxyl functionalized PAMAM dendrimer (PAMAM-COOH) and amino functionalized PAMAM dendrimer (PAMAM-NH2) are used to provide different surfaces with various surface hydrophilicity, electric charge and roughness. We show that electric charge of a surface is the most important factor influencing non- specific adsorption of live cells to the surface while hydrophilicity/hydrophobicity of a surface is the most important factor for dead cells. Atomic force microscopy, water contact angle and microscopy are used to characterize and confirm surface modifications. To further exploit and improve capturing efficiency of target cancer cells, we investigate the effect of the length of spacers that tether capturing aptamer to the microfluidic surfaces on capturing performance of CCRF-CEM circulating tumour cells. Aptamers with different lengths of thymine base spacers are immobilized onto PAMAM dendrimer modified surfaces in microfluidic channels. We demonstrate that ten thymine bases spacer has the best length for sgc8 aptamer to form its secondary structure for CCRF-CEM cell capture. Water contact angle, and microscopy are used to characterize and confirm surface modifications. Taken together, the results of this study significantly highlight the importance of different considerations on surface modification and its optimizations when designing a microfluidic system for high sensitivity detection and biosensing applications.
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Livres sur le sujet "PDMS surface"

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R, Hilf E., Kammer F et Wien K, dir. PDMS and clusters : Proceedings of the 1st International Workshop on the Physics of Small Systems, held on the island of Wangerooge, Germany, September 8-12, 1986. Berlin : Springer-Verlag, 1987.

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Spectral theory and geometric analysis : An international conference in honor of Mikhail Shubin's 65th birthday, July 29 - August 2, 2009, Northeastern University, Boston, Massachusetts. Providence, R.I : American Mathematical Society, 2010.

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Chapitres de livres sur le sujet "PDMS surface"

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Qiu, Wenjun, Chaoqun Wu et Zhigang Wu. « Surface Modification of PDMS in Microfluidic Devices ». Dans Concise Encyclopedia of High Performance Silicones, 141–50. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781118938478.ch10.

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Jia, Ruokun, Juan Luo et Liying Zhen. « Copy the Super-Hydrophobic Honeycomb Structure to PDMS Surface ». Dans Advances in Intelligent and Soft Computing, 787–93. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-25194-8_92.

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Li, Lihua, Venkata Subu Mangipudi, Matthew Tirrell et Alphonsus V. Pocius. « Direct Measurement of Surface and Interfacial Energies of Glassy Polymers and Pdms ». Dans Fundamentals of Tribology and Bridging the Gap Between the Macro- and Micro/Nanoscales, 305–29. Dordrecht : Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-0736-8_20.

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Cho, Woong, Yong Jun Ko, Yoo Min Ahn, Joon Yong Yoon et Nahm Gyoo Cho. « Surface Modification Effect of Wettability on the Performance of PDMS-Based Valveless Micropump ». Dans Experimental Mechanics in Nano and Biotechnology, 297–300. Stafa : Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-415-4.297.

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Ketata, M., A. Ayadi, Ch Bradai et N. Elkissi. « Effect of the Radial Flow and Average Molecular Weight on the Surface Defect in PDMS Extrusion ». Dans Design and Modeling of Mechanical Systems—III, 623–29. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-66697-6_60.

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Wang, Bin, Sorin Nita, J. Hugh Horton et Richard D. Oleschuk. « Surface Modification of PDMS for Control of Electroosmotic Flow : Characterization Using Atomic and Chemical Force Microscopy ». Dans Micro Total Analysis Systems 2002, 431–33. Dordrecht : Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0295-0_144.

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Yang, Paul. « Minimal Surfaces in CR Geometry ». Dans Geometric Analysis and PDEs, 253–73. Berlin, Heidelberg : Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-01674-5_6.

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Weinerfelt, Per. « Generation of Surface Grids Using Elliptic PDEs ». Dans Multiblock Grid Generation, 45–47. Wiesbaden : Vieweg+Teubner Verlag, 1993. http://dx.doi.org/10.1007/978-3-322-87881-6_7.

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Fornasier, M. « Compressive Algorithms—Adaptive Solutions of PDEs and Variational Problems ». Dans Mathematics of Surfaces XIII, 143–69. Berlin, Heidelberg : Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03596-8_9.

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Diop, El Hadji S., et Radjesvarane Alexandre. « Analysis of Intrinsic Mode Functions Based on Curvature Motion-Like PDEs ». Dans Curves and Surfaces, 202–9. Cham : Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-22804-4_15.

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Actes de conférences sur le sujet "PDMS surface"

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Ganapathy Subramani, Balasubramanian, et Ponnambalam Selvaganapathy. « Surface Micromachined PDMS Microchannels ». Dans ASME 2007 5th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2007. http://dx.doi.org/10.1115/icnmm2007-30169.

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A new surface micromachining technique for Poly dimethylsiloxane (PDMS) microchannels has been developed to address the leakage problem affecting traditional PDMS microchannel process with embedded tall structures or sudden topographical transitions. Bulk micromachined PDMS cannot be conformally bonded with the surfaces having tall topological features such as thick film electrodes, porous reactor beds and other structural features. Surface micromachining technique with PDMS as structural material and photoresist as a sacrificial material allows the creation of PDMS microchannels on substrates with significant topography. Adhesion of the structural layer with the substrate was characterized for different prepolymer ratios using standard tensile test and 1:3 (Curing agent: base) combination was found to be the best with maximum adhesion strength of 7.5 MPa. The effectiveness of this technique is demonstrated by the fabrication of microchannels with embedded 6μm thick Silver electrodes. The microchannels were leak proof and conformal contact between the PDMS and electrode was confirmed through SEM. The release time for microchannels was reduced to 1 min irrespective of the length of the microchannel. The extension of this technique for fabrication of multi layered microchannel structure was demonstrated through a microfluidic valve. The valve closure occurred at 6.37 kPa.
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Huang, Zhengyong, Feipeng Wang et Jian Li. « Transforming PDMS surface to super-hydrophobic by surface arc-discharge ». Dans 2015 IEEE 11th International Conference on the Properties and Applications of Dielectric Materials (ICPADM). IEEE, 2015. http://dx.doi.org/10.1109/icpadm.2015.7295266.

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Almutairi, Zeyad, Carolyn Ren et David Johnson. « Effects of Hydrophobic Recovery of Plasma Treated PDMS Microchannels on Surface Tension Driven Flow ». Dans ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels collocated with 3rd Joint US-European Fluids Engineering Summer Meeting. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-31243.

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Surface tension driven flow is used in numerous microfluidic applications. It is considered a passive pumping technique which doesn’t require any external energy, aside from the interfacial surface energy between the fluid and walls. Thus, it is preferred in applications where the goal is fluid and sample transport. In many applications PDMS (Polydimethylsiloxane) is the most adapted material for chip manufacturing in microfluidics. PDMS has several aspects that make it favorable for microfluidic applications. Ease of chip fabrication, cost effectiveness, chemical stability, and good optical properties are features offered by PDMS and desirable for microfluidics. On the other hand, PDMS has some shortcomings. One of importance is that PDMS is naturally hydrophobic. For this reason it is hard to achieve surface tension flow in native PDMS for various fluids used in microfluidics. Thus, native PDMS must be treated to get hydrophilic surface properties. The most used method for altering PDMS properties to a hydrophilic state is by plasma treatment. This treatment has several aspects where it enhances the attachment of PDMS to substrates, it alters the surface from a hydrophobic to a hydrophilic state, and it increases the electrokinetic properties of PDMS. As a result, after plasma treatment surface tension pumping can be achieved in PDMS, unlike native PDMS. However, plasma treatment is not permanent due to the diffusion of non-cured PDMS species to the surface of microchannels, as is well documented in the literature. The change of plasma treated PDMS with time will affect both the electrokinetic and surface tension driven flow. To our knowledge, researchers have quantitatively documented the time effect on plasma treated PDMS microchannels (aging of PDMS) for electrokinetic flow, but not for surface tension driven flow. Therefore, a quantitative examination of the time effect on surface tension driven flow for plasma treated PDMS gives valuable information on both regaining the hydrophobic properties in PDMS and changes in the passive flow conditions. In this work a quantitative study on the hydrophobic recovery for oxygen-plasma treated PDMS and its effects on surface tension flow was examined. The study was performed with a quantitative flow visualization technique (micro particle image velocimetry). It was found that the aging of PDMS will strongly affect surface tension flow of water based solutions in PDMS microchannels. This study gives important information on the effectiveness of surface tension driven flow for oxygen plasma treated PDMS microchannels.
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Ishibashi, G., K. Asada et S. Maruo. « Surface tension-driven autonomous tweezers using PDMS sheets ». Dans 2013 International Symposium on Micro-NanoMechatronics and Human Science (MHS). IEEE, 2013. http://dx.doi.org/10.1109/mhs.2013.6710480.

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Goraus, Matej, Dusan Pudis, Daniel Jandura et Sofia Berezina. « PDMS-based waveguides with surface relief Bragg grating ». Dans 20th Slovak-Czech-Polish Optical Conference on Wave and Quantum Aspects of Contemporary Optics, sous la direction de Jarmila Müllerová, Dagmar Senderáková, Libor Ladányi et Ľubomír Scholtz. SPIE, 2016. http://dx.doi.org/10.1117/12.2264355.

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Wang, Kaiying, Guangming Ouyang et Xuyuan Chen. « Surface modification and wettability of silicone PDMS film ». Dans 2010 3rd Electronic System-Integration Technology Conference (ESTC). IEEE, 2010. http://dx.doi.org/10.1109/estc.2010.5642871.

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Park, Dong-su, Jiajun Xu et Kyoung-Su Park. « Wettability Control of PDMS Surface Coated on the Glass Using Ultrasonic Vibration Treatment ». Dans ASME 2020 29th Conference on Information Storage and Processing Systems. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/isps2020-1954.

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Abstract In this study, a method was proposed to change the surface roughness of Polydimethylsiloxane (PDMS) membrane, a hydrophobic material coated on circular steel substrates, using ultrasonic vibration with frequency above 20 kHz to control the surface tension of water droplet on the PDMS membrane. Ultrasonic vibration applied from piezo actuator was transmitted through circular steel substrate to PDMS membrane and it made the PDMS (liquid) vibrated. It made surface roughness of PDMS membrane changed. The results of coating the PDMS membrane on the circular steel substrate and measuring the contact angle of the water droplet after applying ultrasonic frequency vibration showed that ultrasonic frequency vibration could affect the surface roughness of the PDMS membrane. In this paper, we compared and discussed the surface roughness effects on various vibration frequencies and amplitudes.
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Hung, Lung-Hsin, et Abraham P. Lee. « Optimization of Droplet Generation by Controlling PDMS Surface Hydrophobicity ». Dans ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-61737.

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This paper presents an optimized method for droplet generation in PDMS microchannels. With controllable PDMS surface hydrophobicity and hydrophobicity recovery, alternative component droplets can be generated as anticipated. Different surface hydrophobicity results in different droplet generation patterns. Monodispersed water-in-oil and oil-in-water droplets are generated from hydrophilic and hydrophobic surface respectively. Nearly hydrophilic surface (30°<θ<50°) results in long-tailed droplets and less hydrophilic surface (70°<θ<80°) results in stream mixing. Discussion of methods to loss and recovery hydrophobicity of PDMS also included.
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Almutairi, Zeyad, Carolyn Ren et Leonardo Simon. « Improving the Electrokinetic Properties of PDMS With Surface Treatments ». Dans ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels collocated with 3rd Joint US-European Fluids Engineering Summer Meeting. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-31241.

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PDMS (Polydimethylsiloxane) is widely used as a microfluidic chip material for various applications due to its desirable properties [1, 2]. However PDMS has several drawbacks that limit its utilization in a number of microfluidic applications [1–4]. Properties such as the hydrophobic nature, sample absorption, and low electrokinetic properties (low zeta potential) are some issues that must be considered before using PDMS for numerous applications [3]. In many PDMS based chips electroosmotic pumping is used for fluid flow and sample transport along the microchannel networks. Simplicity of implementation in microfluidic chips, fast response time, and the plug-like velocity profile are the major advantages of electroosmotic flow compared to other fluid pumping techniques [2]. This type of flow utilizes the formation of electric double layer (EDL) in microchannels and the movement of ions under an applied external electric field. Thus, the surface properties of the channel material and liquid properties (ionic concentration, pH, and viscosity) play major roles in electroosmotic pumping for different solutions in microchannels.
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Lee, S., et N. D. Spencer. « Influence of Surface Modification on Aqueous Lubrication of Elastomers ». Dans World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63234.

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Water is generally not an efficient lubricant for most tribosystems due to its extremely low pressure-coefficient of viscosity. This barrier is less important, however, when elastomers are employed as tribopairs, since a low-pressure, conformal contact is readily achieved under these conditions, and thus the isoviscous-elastic lubrication (or soft elastohydrodynamic lubrication, “soft EHL”) mechanism can be activated. Isoviscous-elastic lubrication does not necessitate the increase of viscosity under pressure. The aqueous lubrication of elastomers, however, requires a careful control of surface properties of tribopairs since hydrophobic interactions between the sliding surfaces in water can result in the failure of lubricating films to form at low sliding speeds. In this context, we have investigated the influence of surface modification of an elastomer, poly(dimethylsiloxane) (PDMS), on its aqueous lubrication properties. A dramatic reduction in frictional forces has been observed upon hydrophilization by oxygen-plasma treatment when PDMS was slid against PDMS in an aqueous environment. A similar effect was also observed when the PDMS surface was coated with a variety of copolymers that possess amphiphilic characteristics. This effect is attributed to the removal of the strong hydrophobic interaction between PDMS surfaces in water, thereby enabling the soft EHL mechanism to predominate. This study demonstrates the significance of surface modification in allowing effective soft EHL of an elastomer to take place.
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Rapports d'organisations sur le sujet "PDMS surface"

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Alam, Todd M. IR Imaging of PDMS Degradation Thin Films on Metal Surfaces. Office of Scientific and Technical Information (OSTI), février 2019. http://dx.doi.org/10.2172/1495429.

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