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1
Khakalo, Alexey, Jarmo Kouko, Elias Retulainen, and Orlando J. Rojas. "Super-stretchable paper-based materials for 3D forming." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-236369.
Full textAbstract:
Paper is renewable, recyclable, sustainable and biodegradable material and, as a result, paper-based materials are widely used in the world packaging market. However, paper-based materials cannot compete with plastics in terms of processability into various 3D shapes. This is due to poor formability of paper, which is closely associated with its toughness. To improve paper formability, we report on a facile and green method that combines fiber and paper mechanical modifications at different structural levels as well as biopolymer treatment via spraying. As a result, a remarkable elongation of ∼30% was achieved after proposed combined approach on the laboratory scale. At the same time, a significant increase in tensile strength and stiffness (by ∼306% and ∼690%, respectively) was observed. Overall, an inexpensive, green, and scalable approach is introduced to improve formability of fiber networks that in turn allows preparation of 3D shapes in the processes with fixed paper blanks such as vacuum forming, hydroforming, hot pressing, etc.
2
Alfthan, Johan. "Micro-mechanically based modeling of mechano-sorptive creep in paper." Doctoral thesis, KTH, Solid Mechanics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-41.
Full textAbstract:
The creep of paper is accelerated by moisture content changes. This acceleration is known as mechano-sorptive creep, which is also found in wood and some other materials. Mechano-sorptive creep has been known for several decades but it is still not well understood, and there is no generally accepted model explaining the effect.
In this thesis, it is assumed that mechano-sorptive creep is the result of transient redistributions of stresses during moisture content changes in combination with non-linear creep behaviour of the material. The stress redistributions are caused by the anisotropic hygroexpansion of the fibres, which will give a mismatch of hygroexpansive strains at the bonds and hence large stresses each time the moisture content changes. This redistribution will lead to an uneven stress state. If the creep of the material depends non-linearly on stresses this will give an increase in creep rate where the stresses are high, that is larger than the decrease of creep rate where stresses are low, so in average there will be an increase in creep rate. The stress distribution evens out as the stresses relax during creep, and the moisture content has to change again to create a new uneven stress state and maintain the accelerated creep.
Two different network models based on this mechanism are developed in this thesis. Numerical simulations show that the models produce results similar to the mechano-sorptive creep found in paper. In the first model it is assumed that creep takes place in the fibre-fibre interfaces at the bonds, in the second the creep of the fibres themselves is accelerated. The second model is further developed. Experiments verify model predictions of the dependence of the amplitude of moisture changes.
The second model shows a linear relationship between mechanical load and deformation, although creep of the fibres depends non-linearly on stresses. This linear behaviour is also found in applications. Further analysis shows that the mechanical load can be treated as a small perturbation of the internal stress state caused by moisture content changes. This can be used to develop a linearized model, from which a continuum model can be derived. This leads to a reduction of the necessary number of variables, and a significant increase in speed of calculations. Hence, this linearized continuum model can be used as a constitutive law of paper in problems with complicated geometries, for example a corrugated board box in varying humidity.
3
Uusi-Tarkka, Eija Katariina. "Bio-based nonwoven fabric-like materials produced by paper machines." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-10690.
Full textAbstract:
The purpose of this thesis is, in collaboration with the Swedish company Innventia, to explore the possibilities of using paper machines to create fabric-like nonwoven materials. As part of a relatively new research-area, it serves as some of the ground knowledge that is needed to drive this field forward. The research of this thesis is born from the increasing need for more environmental friendly textiles, and to find new uses for the paper production facilities and companies that are currently experiencing a decline in paper production. The materials used in the research were produced with the Finnish handsheet former and the StratEx sheet-maker made by Innventia. The research consists of the following tests: Tissue Softness Analysis, (TSA), tensile strength and bending stiffness. The tests are done with different combinations of lyocell, PLA, softwood and dissolving pulp in the tested sheets. It is also tested if the lyocell can be a meaningful substitution for PLA in combination with softwood pulp and dissolving pulp when creating the fabric-like materials. In conclusion of this research it can be said that, compared to benchmarking samples like bedding sheets, table cloths and cotton shirts, the sheets created and tested are competitive alternatives to existing materials when it comes to softness. It also became clear that the tensile strength has to be increased to make fabric-like nonwoven materials applicable on the same level as existing textiles. Even so, it is still evident that there is a potentiality in the use of paper machines in the development and creation of new fabric-like materials.
4
Ryder, Kathryn. "The development of paper-based materials from low-grade apparel waste." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/the-development-of-paperbased-materials-from-lowgrade-apparel-waste(9aef77c7-57ac-4cf1-8d4b-0d6952dd4f19).html.
Full textAbstract:
The recycling rate of post-consumer apparel waste is low. This is compounded by our limited understanding of the fibre recovered from apparel waste and a lack of development in novel applications. Motivated by the growing rate of accumulation in unwanted clothing, this study focused on a number of integrated research themes aimed at understanding the nature of reclaimed cotton fibre, its use in paper-based materials and its utilisation in apparel related applications. Initially, the investigation characterised reclaimed cotton fibres from two different recovery machines (pinned air-layer and cutting mill). The results showed that neither process was capable of producing adequate fibre quality for fine yarn manufacture. The fibres exhibited extensive surface damage, length shortening and an increase in length distribution. After the initial characterisation, studies were undertaken to investigate the use of paper technology to increase the possibility of using reclaimed fibre in apparel. Strength is an important property in apparel related applications, therefore, the strength of reclaimed cotton-based paper was enhanced. The effects of a 4% sodium hydroxide pre-treatment on the beating performance and resultant sheet properties of reclaimed fibre pulp were investigated. At low beating levels, the results showed a significant 35% and 39% increase in tensile strength and energy absorption, respectively. With the treatment it is, therefore, possible to obtain a strong paper with high bulk, which can be further utilised to improve surface softness. Optimum dry and wet strength enhancement of the resultant paper was obtained with the combined addition of 1% carboxymethyl cellulose and 2% polyamideamine-epichlorhydrin. The development of wet strength was vital in order to facilitate uniform twist insertion in subsequent paper yarn manufacture. This study was one of the first to test the viability of using reclaimed cotton fibre in the production of paper yarns suitable for apparel manufacture. The wet-strengthened reclaimed-fibre paper was slit into 3 mm width ribbons, dampened, then twisted into yarns. The resultant yarns (46–193 tex) were uniform but lacked sufficient strength for use in weaving and knitting processes. Analysis of a commercial paper yarn, OJO+ , suggested that strength could be improved if fibre orientation was increased in the machine direction. A further application, in the form of a jacket, was trialled. The focus here was to test sewability using a variety of seam and stitch formations to sew together denim-derived cotton paper. A simple design using lap seams with straight stitching was established as the most effective construction. The final jacket satisfied industry requirements on seam strength and efficiency, however, further investigation into improving comfort and wear-ability will be essential.
5
Liu, Cheyenne H. "Development and Characterization of Reagent Pencils for Microfluidic Paper Based Analytical Devices." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1639.
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Microfluidic paper based analytical devices (microPADs) are a novel platform for point of care (POC) diagnostics. Limitations of reagent shelf life have been overcome with the introduction of reagent pencils as a method for solid-based reagent deposition. While useful, little work has been reported on the characterization and optimization of reagent pencils. Herein, an investigation on reagent pencil composition and efficiency is conducted via colorimetric release profile tests utilizing an erioglaucine disodium salt that yields a quantifiable blue colored product in the presence of water. Within this work, an investigation on the molecular weight dependence, polymer chain end functionality, and polymer-graphite ratio was conducted to determine the most desirable parameters in reagent pencil composition. Further, the effects of enzyme stability in the presence of poly(ethylene glycol) (PEG) is investigated.
To show the versatility of reagent pencils, a novel reagent pencil incorporating a stimuli responsive polymer, poly(N-isporopylacrylamide) (PNIPAM) was developed. In this work, PNIPAM’s lower critical solution temperature (LCST) was manipulated with various salt solutions to control fluid flow both laterally and vertically through various microPAD designs. It was found that, while PNIPAM successfully blocked or retarded fluid flow in microPADs, the effect was limited when DI H2O wash solutions were run prior to salt solutions. To counteract this, PNIPAM was successfully covalently bound to alkene modified chromatography paper via thiolene click chemistry to reinforce solution wash tolerance.
6
Glavan, Ana. "Chemical Approaches to the Surface Engineering of Paper and Cellulose-Based Materials for Microfluidics, Electronics and Low-Cost Diagnostics." Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:26718749.
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Paper (and other cellulose-based materials such as cotton thread and fabrics) are underexploited as materials for the construction of “high-tech” and “lab-on-a-chip” devices. One major drawback of paper is its tendency to absorb water from the environment and, with wetting, to change its mechanical properties; other challenges relate to control over the attachment of molecules (e.g. antibodies, DNA) and cells on its surface, and to the addition of electronic function. The goal of this thesis is to develop paper as a substrate for a range of applications— microfluidics, substrates for electronic systems and MEMS, low-cost diagnostics, cell biology, and optics. The approach involves chemically modifying the surface of the paper to provide new functions without altering any of its defining properties: mechanical flexibility, foldability, light weight, gas permeability, and low cost.
The first part of my thesis describes the modification of paper by silanization with organosilanes such as alkyl- and fluoroalkyl trichlorosilanes in the gas phase. Here, silanization is used to lower the surface free energy of the paper and to minimize the tendency of paper to absorb liquids and vapors, and especially water. Chapter 1 and Appendix 3 demonstrate that the combination of long fluoroalkyl chains of grafted siloxanes with the micro-scale roughness and porosity of paper yielded a material that is omniphobic (both hydrophobic and oleophobic), while preserving the properties of mechanical flexibility and low resistance to transport of gas of the untreated paper. Appendix 3 shows that features of omniphobic paper can be used to construct microtiter plates and liquid-filled gas sensors using standard paper folding techniques, while Appendix 4 shows that new type of microfluidic device fabricated by carving microchannels into the surface of omniphobic paper. The resulting devices have open, unobstructed channels (with dimensions as small as 45 μm) and thus exhibit fluid dynamics similar to conventional PDMS-based microfluidics, but are much lighter and have the potential to be much less expensive than PDMS-based devices.
The second part of my thesis is focused on engineering the surface of paper to enable efficient immobilization of capture and target molecules for bioanalysis. In one approach, described in Appendix 5, we exploit the ease with which the surface chemistry of paper (i.e. the surface of the cellulose fibers making up the paper) can be modified, in order to enhance the immobilization of antibodies and antigens on the surface of the paper via hydrophobic interactions, while preventing the wicking of the fluids into the paper substrate. As an application in low-cost diagnostics, we describe a low-cost electrochemical device for ELISA intended for use in resource-limited settings. In a second approach, described in Chapter 2, we developed of an efficient procedure for assembling microarrays of ssDNA and proteins on paper, at the lowest practical cost. This method starts with the synthesis of DNA oligonucleotides covalently linked to paper, and proceeds to generate ssDNA arrays that, through hybridization with complementary strands of DNA, are capable of simultaneously capturing DNA, DNA-conjugated protein antigens, and DNA-conjugated antibodies.
The third part of my thesis describes the simple, inexpensive fabrication of electrodes for paper-based electrochemical systems. A first method describes, in Appendix 6, the development of inkjet printing as a method for high resolution printing of conductive patterns on omniphobic “RF” paper, both to extend its promise as a substrate for paper electronics, and to enable us to integrate it into our program in low-cost, paper based diagnostics. A second method, described in Chapter 3, circumvents the need for printing, and instead focuses on the fabrication and reconfiguration of simple, versatile, and inexpensive electroanalytical devices in which conventional stainless-steel pins—in unmodified form or after coating with a carbon paste—are used as electrodes.Chemistry and Chemical Biology
7
Paudyal, Janak 9255967. "Carbon Nanotube- and Gold Nanoparticle-Based Materials For Electrochemical and Colorimetric Sensing Applications." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2996.
Full textAbstract:
Carbon nanotubes (CNTs) and gold nanoparticles (AuNPs) are widely used for sensing applications due to their distinctive electrical and optical properties, and we have explored the development of methods that enable the incorporation of these nanomaterials into new and improved sensing devices.
As a means for fabricating simple, low-cost and fast detection platforms for various applications, we have developed paper-based electrochemical detection platforms based on CNTs or platinum nanoparticle (PtNP)-CNT composite materials. We describe the use of a paper-based, low density, a three-dimensional thin film of interconnected CNTs as an electrode material. We studied the electrochemical properties of these paper-based CNT electrodes and demonstrated their use as an electrochemical sensor for the sensitive detection of guanine-based nucleotides. We further describe the functionalization of this paper-based electrode by fabricating a PtNP-SWCNT hybrid film via a vacuum filtration-based method. The interconnected PtNP structure formed on top of the CNT-coated paper was directly used as an electrocatalyst for methanol oxidation. Compared to paper-based PtNP-SWCNT hybrid films formed by electrochemical deposition, hybrid films formed by vacuum filtration showed a higher electrochemical surface area and enhanced electrocatalytic response to methanol oxidation.
We have also developed methods based around DNA-modified AuNPs, which offer an excellent colorimetric platform for target detection. The DNA density on the surface of modified AuNPs affects enzymatic activity, colloidal stability of AuNPs, the orientation of the probe DNA and its hybridization efficiency. The combination of all these factors ultimately dictates the reaction time and sensitivity of colorimetric assays. We demonstrate the use of DTT as a modulator to control DNA surface coverage on the surface of AuNPs. Using this DTT treatment and a novel probe for exonuclease III activity, we have developed a colorimetric assay based on DTT-treated, DNA-modified AuNPs that can achieve more sensitive and rapid detection of DNA and enzymes relative to existing sensor platforms.
8
Mitchell, Haydn Thomas. "AN INVESTIGATION OF POLY(N-ISOPROPYLACRYLAMIDE) FOR APPLICATIONS WITH MICROFLUIDIC PAPER-BASED ANALYTICAL DEVICES." DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1248.
Full textAbstract:
N,N′-methylenebisacrylamide-crosslinked poly(N-isopropylacrylamide), also known as P(NIPAM), was developed as a fluid delivery system for use with microfluidic paper-based analytical devices (microPADs). MicroPADs are postage-stamp-sized devices made out of paper that can be used as platforms for low-cost, simple-to-use point-of-care diagnostic assays. P(NIPAM) is a thermally responsive polymer that absorbs aqueous solutions at room temperature and will expel the solutions to microPADs when heated. The fluid delivery characteristics of P(NIPAM) were assessed, and P(NIPAM) was able to deliver multiple solutions to microPADs in specific sequences or simultaneously in a laminar-flow configuration. P(NIPAM) was then shown to be suitable for delivering four classes of reagents to microPADs: small molecules, enzymes, antibodies and DNA. P(NIPAM) successfully delivered a series of standard concentrations of glucose (0 – 5 mM) to microPADs equipped to perform a colorimetric glucose assay. The results of these tests were used to produce an external calibration curve, which in turn was used to determine accurately the concentrations of glucose in sample solutions. P(NIPAM) successfully delivered fluorescein-labeled IgG and fluorescein-labeled oligonucleotides (20 base pairs) to microPADs in a variety of concentrations. P(NIPAM) also successfully delivered horseradish peroxidase (HRP) to microPADs, and it was determined that HRP could be stored in P(NIPAM) for 35 days with minimal loss in activity. The combination of P(NIPAM) with microPADs will allow for more complex assays to be performed with minimal user input, will facilitate the preparation of external calibration curves in the field, and may be useful in extending the shelf life of microPADs by stabilizing reagents.
9
Kripalani, Rishi A. "Novel Integration of Conductive-ink Circuitry with a Paper-based Microfluidic Battery as an All-printed Sensing Platform." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1694.
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The addition of powered components for active assays into paper-based analytical devices opens new opportunities for medical and environmental analysis in resource-limited applications. Current battery designs within such devices have yet to adopt a ubiquitous circuitry material, necessitating investigation into printed circuitry for scalable platforms. In this study, a microfluidic battery was mated with silver-nanoparticle conductive ink to prototype an all-printed sensing platform. A multi-layer, two-cell device was fabricated, generating 200 μA of direct electrical current at 2.5 V sustained for 16 minutes with a power loss of less than 0.1% through the printed circuitry. Printed circuitry traces exhibited resistivity of 75 to 211 10-5 Ω m. Resistance of the printed traces increased upwards of 200% depending on fold angle and directionality. X-ray diffraction confirmed the presence of face-centered cubic silver after sintering printed traces for 30 minutes at 150°C in air. A conductivity threshold was mapped and an ink concentration of 0.636 μL mm-3 was identified as the lower limit for optimal electrical performance.
10
Wu, Chuen-Lin, and 吳權霖. "Studies on the Protective Materials for Paper-Based Cultural Relics." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/34074508100264935916.
Full textAbstract:
碩士中興大學
森林學系所
95
Summary Three kinds of material, plastics, wood and paper, have been adopted in this study for paper-based cultural relics’ protection. The permanence and performance of these materials in the protection of aged relics are our main concerns and have been well discussed. Furthermore, some laboratory-made alkaline handsheets were used to carry out the deacidification of acidic paper in this study. The effects of deacidification on paper relics’ permanence were also evaluated. The experimental results were summarized as follows: 1. After outdoor aging, the plastic board made mainly from PVC and film became yellow and embrittled easily. Instead, the A, C acrylic boards and polyester films still retained good strength and transparency; they also had longer service life and better weather-durability. So, they are more suitable as protective materials for paper-based cultural relics. 2. Eight wooden boards were stacked with filter paper and woodfree printing paper for three hundred days. They all induced negative effects on papers, especially Cryptomeria japonica, Chamaecyparis formosensis and Chamecyparis obtusa. The above-mentioned three wooden materials caused the papers to severe foxing. Among the eight, Picea mariana caused the least change in the color difference of papers. Furthermore, when a metal wire was put between the paper and wooden materials, however the paper still became yellow even though the paper did not have direct contact with the wooden materials. 3. After the accelerated aging with high temperature and humidity, the scale of the color reversion and reduction in strength of acidic sized paper were more serious than that of alkaline sized paper. Color reversion became a rapid and unavoidable problem for the paper containing mechanical pulp. The load of CaCO3 in alkaline paper would act as acid-neutralizer and gradually decrease degradation during the aging of paper. Local-made fine papers are still not as good as imported acid-free papers. The higher content of lignin in local-made fine papers makes them unjustified to meet the definition of acid-free paper. 4. The addition of AKD decreases the strength and lowers the pH value of paper. Strength improvement can be achieved by adding the cationic starch, cationic retention aid-flocculants, and the pH value can be lifted by loading of alkaline filler. The property of alkaline paper, with addition of 0.1% AKD, 0.5% cationic starch, 0.5% cationic retention aid-flocculants and 5% CaCO3, was found to be the best in our study. Besides, the pH value of acidic papers could be increased, by pressing treatment with laboratory-made alkaline paper, to the extent of imported acid-free papers. By increasing the amounts of alkaline filler or the pressing pressures, it could decrease the pressing time and increase the pH value of acidic paper effectively.
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Chen, Chun-Yu, and 陳俊宇. "Influence of wood case materials on the preservation of paper-based cultural relics." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/82861396595193577082.
Full textAbstract:
碩士國立嘉義大學
林業暨自然資源研究所碩士班
93
Summary Wood is a famous for it is of strength and durability, and its use for display case and exhibiting valuables. However, wood is an acid material and releases acidic substance that causes the acid degradation of cellulose and the problem of paper preservation. This study explores the effects of different wood case on the paper properties after storage classical-collection materials. The paper is subjected to 103 ±2℃ degree accelerated aging for 10 days and long-term aging about 12 months; the change in the physical properties of paper, color difference value, pH value, the experimental results are summarized as follows: 1. When the paper is piled on the Paulownia and Sen board by accelerated aging for 10 days; the paper has the best physical property followed by Red cypress and medium density fiber board. Camphor and oak are to mostly affected, they retain only 50% of the original folding endurance and tear factor. 2. After 10 days of accelerated aging, the paper piled on camphor, red cypress and plywood has the most color difference while the paper piled on paulownias, sen, and oak has least color difference. 3. After long-term aging for 12 months, there are no significant differences between the testing paper control in terms of paper physical property, color difference value, and pH value. 4. Due to the release of organic acid solvent thought the paint film which accelerates the degradation of paper. While ether flooding and Polyethylene / aluminum foil covering of paper increase or preservation of paper. 5、On comparison with the control group after accelerated aging test, all the paper samples piled on wooden material have lower physical properties, brightness, color difference value and pH value than those control groups. This explains the extractives in wood would induce degradation of paper affect paper preservation.
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Huang, Yen-Chieh, and 黃彥傑. "Effect of Learning Recommendation on Learning Performance in a Paper-based and Digital Materials Seamlessly Integrated System." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/78338393514706043833.
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碩士國立中山大學
資訊管理學系研究所
98
Books and printed materials have been used as a major learning content for thousands of years. Nowadays, Smartphone is considered as an important tool for mobile learning. This study designed a learning environment with paper and Smartphone which seamlessly integrates printed materials and digital materials. The idea is to augment the traditional paper-based materials with plenty of digital materials available on the Internet. Furthermore, because both book and Smartphone are with very good mobility, the designed system is also very suitable for mobile learning. Two special mechanisms were designed for supporting learning activities, and their effects on learning performance were evaluated. The first one is learning recommendation which is generated based on the learning portfolio. The second one is automated content connection which can reduce the loading of context switching between printed materials and digital materials so as learners can be more concentrated on learning tasks. A system was designed and implemented for conducting an experiment and data collection. The statistic analysis shows that learning recommendation has a significant positive effect on learning performance; however, the effect of automated content connection on learning performance is not significant. Besides, the questionnaire survey also shows that learners have positive attitude toward the acceptance of the learning system designed in this study. Based on the results, some implications and suggestions are provided for researchers and instructors.
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Lee, Cheng-Han, and 李政翰. "Effect of Scaffolded Questioning on English Reading Comprehension in a Paper-based and Digital Materials Seamlessly Integrated System." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/40870684471979222230.
Full textAbstract:
碩士國立中山大學
資訊管理學系研究所
98
Reading from paper-based materials has been a major way for people to acquire knowledge. However, paper-based materials are constricted in presenting abstract and complex knowledge or concepts. Recent development of smartphone makes it a device not only for interpersonal communication, but also for accessing rich digital resources over the Internet. Because both paper-based materials and smartphone are mobile and portable, we can make use of the networking capability of smartphone to access digital materials from the Internet to enrich conventional paper-based reading activities such that students’ reading comprehension can be enhanced. The present study came up with an innovative paper-based reading system integrated with digital materials delivered from the smartphone. QR codes were employed to automatically link the content of the print material with relevant digital resources. Also, questions were given to students along the reading process to scaffold the reading activity in order to help students comprehend the essence of the reading pieces. A quasi-experimental design was used to evaluate the effectiveness of the learning system in improving students’ reading comprehension. The results suggested that whether or not using QR code to automate linking digital and print materials does not significantly influence student reading comprehension; however, using questions to scaffold the reading process significantly improves students’ reading comprehension. The survey conducted in the experiment suggested that most of the students agreed that the integrated learning system benefits English reading comprehension. The implication of the results and suggestions to system design and future studies were then addressed.
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Aliahmad, Nojan. "Paper-based lithium-Ion batteries using carbon nanotube-coated wood microfiber current collectors." Thesis, 2013. http://hdl.handle.net/1805/3652.
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Indiana University-Purdue University Indianapolis (IUPUI)The prevalent applications of energy storage devices have incited wide-spread efforts on production of thin, flexible, and light-weight lithium-ion batteries. In this work, lithium-ion batteries using novel flexible paper-based current collectors have been developed. The paper-based current collectors were fabricated from carbon nanotube (CNT)-coated wood microfibers (CNT-microfiber paper). This thesis presents the fabrication of the CNT-microfiber paper using wood microfibers, coating electrode materials, design and assemblies of battery, testing methodologies, and experimental results and analyses. Wood microfibers were coated with carbon nanotubes and poly(3,4-ethylenedioxythiophene) (PEDOT) through an electrostatic layer-by-layer nanoassembely process and formed into a sheet, CNT-microfiber paper. The CNT loading of the fabricated paper was measured 10.1 μg/cm2 subsequently considered. Electrode material solutions were spray-coated on the CNT-microfiber paper to produce electrodes for the half and full-cell devices. The CNT current collector consists of a network structure of cellulose microfibers at the micro-scale, with micro-pores filled with the applied conductive electrode materials reducing the overall internal resistance for the cell. A bending test revealed that the paper-based electrodes, compared to metal ones, incurred fewer damages after 20 bends at an angle of 300o. The surface fractures on the paper-based electrodes were shallow and contained than metallic-based electrodes. The micro-pores in CNT-microfiber paper structure provides better adherence to the active material layer to the substrate and inhibits detachment while bending. Half-cells and full-cells using lithium cobalt oxide (LCO), lithium titanium oxide (LTO), and lithium magnesium oxide (LMO) were fabricated and tested. Coin cell assembly and liquid electrolyte was used. The capacities of half-cells were measured 150 mAh/g with LCO, 158 mAh/g with LTO, and 130 mAh/g with LMO. The capacity of the LTO/LCO full-cell also was measured 126 mAh/g at C/5 rate. The columbic efficiency of the LTO/LCO full-cell was measured 84% for the first charging cycle that increased to 96% after second cycle. The self-discharge test of the full-cell after charging to 2.7 V at C/5 current rate is showed a stable 2 V after 90 hours. The capacities of the developed batteries at lower currents are comparable to the metallic electrode-based devices, however, the capacities were observed to drop at higher currents. This makes the developed paper-based batteries more suitable for low current applications, such as, RFID tags, flexible electronics, bioassays, and displays. The capacities of the batteries at higher current can be improved by enhancing the conductivity of the fibers, which is identified as the future work. Furthermore, fabrication of an all solid state battery using solid electrolyte is also identified as the future work of this project.
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Matias, Maria Leonor Joaquim do Nascimento. "Paper-based nanoplatforms for multifunctional applications." Master's thesis, 2018. http://hdl.handle.net/10362/58117.
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In this work, zinc oxide (ZnO) and titanium dioxide (TiO2) nanostructures were grown on different cellulose paper substrates, namely Whatman, office, and commercial hospital papers, using a hydrothermal method assisted by microwave irradiation. Pure ZnO and TiO2 nanostructures were synthesized, however the growth of TiO2 above the ZnO was also investigated to produce a uniform heterostructure. Continuous ZnO nanorod arrays were grown on Whatman and hospital papers, however on office paper, it could be observed the formation of nanoplates originating nanoflower structures. TiO2 nanoparticles homogeneously covered all the substrates and, in some conditions, forming uniform TiO2 films. The structural characterization was carried out by SEM coupled with EDS, XRD and Raman spectroscopy. The optical characterization of all the materials was carried out. The produced materials were investigated for multifunctional applications, like photocatalyst agents, bacterial inactivators and ultraviolet (UV) sensors. To evaluate the photocatalytic activity under UV and solar radiations, rhodamine B was the model-test contaminant indicator and the best photocatalytic activity was achieved with Whatman paper. Hospital paper with TiO2 nanoparticles showed significant antibacterial properties against Staphylococcus aureus. ZnO-based UV sensors on Whatman demonstrated a responsivity of 0.61 μA W-1.
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Rubin, Sabrina Josephine. "Development of eco-friendly ZnO inks for paper-based printed electronics." Master's thesis, 2017. http://hdl.handle.net/10362/45647.
Full textAbstract:
In this work, we report the development of printable semiconducting inks compatible
with screen-printing and paper technology and functional at room temperature without
the need of post-deposition treatments. The developed eco-friendly inks are based on a
dispersion of zinc oxide nanoparticles on a cellulose matrix. Several cellulose derivatives
were used to design and engineer such inks looking for the best formulation, printing
conditions and compatibility with cellulose-based substrates. The approach described
here represents an innovative and versatile generation of semiconducting inks composed
of some of the cheapest, renewable and highly abundant materials we can find on Earth,
such as cellulose, able to be implemented as channel in printed transistors on paper.
By using a cellulose-based ion gel as gate dielectric the printed ZnO transistors exhibit
an Ion=of f ratio ranging from 103 to 105, sat values close to 9 cm2 V 1 s1 and gm of
around 0.4 mS.
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Franco, Miguel Alexandre Martins. "Resistance Switching Memory Devices based on Zinc Oxide Nanoparticles on Paper Substrates." Master's thesis, 2016. http://hdl.handle.net/10362/21756.
Full textAbstract:
This work reports the development of resistive random access memory (RRAM) on paper using printed Zinc Oxide (ZnO) nanoparticles (NPs) as active layer. RRAM is a novel technology having attracted increasing attention due to their high-speed operation, high-density storage, and low voltage. Most important, due to its characteristics it could replace flash technology which suffers from low endurance, low write speed, and high voltages required for the write operations.
Screen printing was chosen because of its versatility in terms of ink viscosity, which is compatible with inks that require low annealing temperatures. The architecture adopted consists in a mixture of ZnO NPs and ethyl cellulose (EC), used as binder, between electron beam evaporated platinum bottom electrode and screen-printed carbon or silver top electrode.
The resistive memory device can be programed in bipolar for at most 20 cycles. The retention time of the bipolar switching for both on/off states is reached up to 10 Ks. The operating voltages of SET and RESET is high ~ 20 V and - 10 V respectively. A transition between bipolar switching to unipolar is observed. It is suggested that an instable bipolar resistive switching is due to growth of filaments during cycles. The required voltages for on/off states fluctuate in the range of ~ 5 V which is a strong evidence of non-consistent bipolar resistive switching.
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Fernandes, Alexandra Agostinho Gomes. "An electrochromic paper-based device as a diagnostic test for Cystic Fibrosis." Master's thesis, 2018. http://hdl.handle.net/10362/58114.
Full textAbstract:
Cystic Fibrosis (CF) is an inherited disorder affecting more than 70000 people worldwide, especially Caucasian populations with a carrier prevalence of 1/3000. Currently, it has no cure but an early diagnosis remains a critical issue. Sweat chloride test has been the gold standard to diagnose CF since the affected present sweat chloride concentrations ≥ 60 mM. In this work, a planar electrochromic “point-of-care” device, based on tungsten trioxide nanoparticles produced by microwave assisted hydrothermal synthesis, was developed as a first approach for CF diagnostic testing especially in resource-limited environments. For electrodes patterning, a CO2 laser technology was used in a PET/ITO sheet. The device presents a design that allows the NaCl-based electrolyte deposition, used as artificial sweat, only on time of usage directly on the nanoparticles or in a paper pad. By applying an operating voltage of -3 V, the nanoparticles change their optical properties according to NaCl concentration, presenting a blue colouration with different intensities for different NaCl concentrations. The device was able to differentiate between a positive and negative diagnosis, with a colouration time of only 1 min, using an RGB analysis with a B/R ratio of 1.37±0.03 for 60 mM of NaCl, and a low power consumption.
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Ferreira, Guilherme Mendes. "Eco-energy Smart Card”: A human-interactive all paper based, mechanical energy harvester." Master's thesis, 2019. http://hdl.handle.net/10362/86717.
Full textAbstract:
Nowadays, it is imperative that modern society finds sustainable ways to harvest energy. This means society is forced to look to new ways to generate and store energy, while reducing, simultaneously, the stress on raw materials demand and the amount of waste generated. Our research tackles these two points by making close to zero e-waste clean energy harvesting devices. The core idea behind it is based on the mechano-responsive charge-transfer mechanism and energy-transfer process in π-conjugated polymer at the organic-metal interface layer. A localized forced deformation of the interface has been applied against the polymer surface, allowing charge transfer between material interfaces. The experimental results demonstrated that during contacting force, the conjugated polymer film shows electrical output through the charge transfer mechanism within metal/polymer interfaces. Flexible and low-cost energy harvesting devices built have an active layer constituted by a PANi/cellulose composite which was tapped together to a charge collector layer, that was made from a paper based metallic electrode. These devices have a total maximum power density and maximum current density of 1.75 Wm-2 and 33.5 mA m-2 , respectively. Towards the practical applicability, these devices are able to light up to 40 blue LEDs as well as a commercial humidity sensor.
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Edberg, Jesper. "Flexible and Cellulose-based Organic Electronics." Doctoral thesis, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-136518.
Full textAbstract:
Organic electronics is the study of organic materials with electronic functionality and the applications of such materials. In the 1970s, the discovery that polymers can be made electrically conductive led to an explosion within this field which has continued to grow year by year. One of the attractive features of organic electronic materials is their inherent mechanical flexibility, which has led to the development of numerous flexible electronics technologies such as organic light emitting diodes and solar cells on flexible substrates. The possibility to produce electronics on flexible substrates like plastic or paper has also had a large impact on the field of printed, electronics where inks with electronic functionality are used for large area fabrication of electronic devices using classical printing methods, such as screen printing, inkjet printing and flexography. Recently, there has been a growing interest in the use of cellulose in organic and printed electronics, not only as a paper substrate but also as a component in composite materials where the cellulose provides mechanical strength and favorable 3D-microstructures. Nanofibrillated cellulose is composed of cellulose fibers with high aspect-ratio and diameters in the nanometer range. Due to its remarkable mechanical strength, large area-to-volume ratio, optical transparency and solution processability it has been widely used as a scaffold or binder for electronically active materials in applications such as batteries, supercapacitors and optoelectronics. The focus of this thesis is on flexible devices based on conductive polymers and can be divided into two parts: (1) Composite materials of nanofibrillated cellulose and the conductive polymer PEDOT:PSS and (2) patterning of vapor phase polymerized conductive polymers. In the first part, it is demonstrated how the combination of cellulose and conductive polymers can be used to make electronic materials of various form factors and functionality. Thick, freestanding and flexible “papers” are used to realize electrochemical devices such as transistors and supercapacitors while lightweight, porous and elastic aerogels are used for sensor applications. The second focus of the thesis is on a novel method of patterning conductive polymers produced by vapor phase polymerization using UV-light. This method is used to realize flexible electrochromic smart windows with high-resolution images and tunable optical contrast.
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Pagará, Beatriz Condeço Pinto. "Paper as a Colorimetric Biosensing Platform for Tetracyclines Detection in Milk." Master's thesis, 2018. http://hdl.handle.net/10362/61057.
Full textAbstract:
Tetracyclines are a type of antibiotic that exhibits activity against most gram-positive and gram-negative bacteria. These antibiotics are often added at subtherapeutic levels to feed to act as growth promoters. Due to its low bioavailability, only a fraction of the antibiotic is metabolized in animals, causing waste. These residues can enter human bodies through the food chain and lead to increased antimicrobial resistance, causing allergic or toxic reactions, which led several countries to implement a maximum level of residues for this type of antibiotic. Most methods of detecting TCs are time consuming or inadequate for field analysis. In this way, an inexpensive, easy-to-execute and fast analytical method is required.
In this sense, in the present work a colorimetric biosensor was developed in paper for the detection of four type of tetracyclines, presenting an alternative in the performance of point-of-care tests. Paper is low-cost, abundant, biodegradable and easy to dispose of by incineration.
The construction of the sensors was performed using Lab-on-Paper technology and is based on the synthesis of gold nanoparticles by reducing a gold salt in which tetracyclines constitute the reducing agent itself. Different concentrations of TCs result in the formation of different colour intensities.
Different concentrations of tetracyclines were tested and analysed using ImageJ software, allowing linear calibration lines to be obtained, that relate the concentration of antibiotics in a range between 0.1 and 10 μg/mL and the arithmetic mean of the RGB channels.
Validation tests of the sensors developed with TC in milk were also performed. It was observed that it is possible to detect this type of antibiotic in pre-treated milk, and four forms of milk treatment were studied.
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"Thermal Actuation and Fluidic Characterization of a Fluorescence-Based Multiplexed Detection System." Master's thesis, 2018. http://hdl.handle.net/2286/R.I.50454.
Full textAbstract:
abstract: This work describes efforts made toward the development of a compact, quantitative fluorescence-based multiplexed detection platform for point-of-care diagnostics. This includes the development of a microfluidic delivery and actuation system for multistep detection assays. Early detection of infectious diseases requires high sensitivity dependent on the precise actuation of fluids.
Methods of fluid actuation were explored to allow delayed delivery of fluidic reagents in multistep detection lateral flow assays (LFAs). Certain hydrophobic materials such as wax were successfully implemented in the LFA with the use of precision dispensed valves. Sublimating materials such as naphthalene were also characterized along with the implementation of a heating system for precision printing of the valves.
Various techniques of blood fractionation were also investigated and this work demonstrates successful blood fractionation in an LFA. The fluid flow of reagents was also characterized and validated with the use of mathematical models and multiphysics modeling software. Lastly intuitive, user-friendly mobile and desktop applications were developed to interface the underlying Arduino software. The work advances the development of a system which successfully integrates all components of fluid separation and delivery along with highly sensitive detection and a user-friendly interface; the system will ultimately provide clinically significant diagnostics in a of point-of-care device.Dissertation/Thesis
Masters Thesis Biomedical Engineering 2018
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Gaspar, Diana Filipa Pereira. "Active cellulose-based substrates for application in eletronic devices." Doctoral thesis, 2019. http://hdl.handle.net/10362/77144.
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