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Metal-Organic Frameworks for Carbon Dioxide Capture : Using Sustainable Synthesis RoutesDeole, Dhruva January 2022 (has links)
Globally the combustion of fossil fuels has increased to a greater extent. Carbon dioxide (CO2) a major greenhouse gas isa by-product of such combustion practices. Increase in the quantity of CO2 emissions has resulted in serious environmental issues including global warming, ocean acidification, extreme weather, and much more leaving a direct impact on the human society. To reduce these emissions, we need a more efficient carbon dioxide capturing technology. Using advances in materials science and engineering we can develop newer technologies for the capture of carbon dioxide gas. Metal-organic frameworks (MOFs) constitute a class of three-dimensional porous materials. They have shown applicability in various fields including carbon dioxide capture. A vast variety of MOFs can be synthesized by selecting proper metal salts and organic-linkers to build up the MOF structure. This thesis focuses on the synthesis of MOFs through a sustainable process or green synthesis route. Most of the MOFs in this study have been synthesized at ambient temperature and pressure conditions with deionized water as the primary solvent. A total of eight MOFs were synthesized in this study using two organic-linkers namely, 1,2,4,5-tetrakis(4-carboxyphenyl)-benzene (H4TCPB) and 2,5-dihydroxy-1,4-benzoquinone (H2DHBQ). The metal-salts used were based on hafnium, zirconium, cerium, magnesium, iron and manganese. A number of qualitative and quantitative tests were carried out onthe MOF samples to ensure their quality of produce and performance. The primary focus was to test the materials for their capacity to uptake carbon dioxide (CO2) in a mixture of flue gases. The highest CO2 uptake capacity was recorded to be 3.02 mmol/g (at 293 K and 1 bar) by the H2DHBQ-magnesium based MOF. All the materials showed good results andwere proven to be reusable. All the synthesized MOFs were crystalline in nature, showed a single-phase microstructure and high surface area values. A supplementary study was conducted wherein the powdered MOFs were 3D printed by the Direct Ink Writing (DIW) technique using an alginate binder. The study was satisfactory because the MOFs after being 3D printed, managed to preserve their inherent properties and characteristics. The results were in par with that of their pristine MOF counterparts. / Den globala förbränningen av fossila bränslen har i allt större utsträckning ökat. Koldioxid (CO2) är en avde viktigast växthusgaserna och erhålls som biprodukt från många förbränningsmetoder. Den höga haltenkoldioxid i atmosfären har resulterat i allvarliga miljömässiga konsekvenser inklusive den globaluppvärmningen, försurning av haven, extremt väder och mycket mer som har en direkt påverkan på detmänskliga samhället. För att minska dessa utsläpp behöver vi en mer effektiv koldioxidinfångningsteknologi. Med hjälp av framsteg inom materialvetenskapen kan vi utveckla nyare tekniker för att fångakoldioxid. Metallorganiska ramverk (MOFs) utgör en klass av tredimensionella porösa material. De har visat siganvändbara inom olika områden inklusive infångning av koldioxid. Många variation av MOF material kansyntetiseras från olika metallsalter och organiska ligander för att bygga upp MOF-strukturen. Dettaexamensarbete fokuserar på syntesen av metallorganiska ramverk via en grön syntesväg och en hållbarprocess. En stor del av MOF materialen som erhölls syntetiserades i rumstemperatur och vid normala tryckmed avjoniserat vatten som det primära lösningsmedlet. Åtta MOFs material syntetiserades i detta projekt med två olika organiska ligander, nämligen, 1,2,4,5-tetrakis(4-karboxifenyl)bensen (H4TCPB) och 2,5-dihydroxy-1,4-bensokinon (H2DHBQ). Metallsalternasom användes i synteserna baserades på hafnium(IV), zirkonium(IV), cerium(IV), magnesium(II), järn(II)och mangan(II). Ett antal kvalitativa och kvantitativa tester genomfördes på MOF:arna för att säkerställaderas kvalitet och prestanda. Det primära fokuset var att testa de olika materialen för deras förmåga att taupp koldioxid (CO2) i en blandning av olika gaser (så som kväve, N2). Den DHBQ-magnesium-baseradeMOF:en uppvisade den högsta CO2-upptagningsförmågan som var 3,02 mmol/g. Alla MOF material visadegoda resultat och visade sig även vara återanvändbara. Alla syntetiserade MOF:ar hade god kristallinitet,uppvisade en singulär fas samt hög ytarea. En kompletterande studie genomfördes där de syntetiserade MOFs materialen (i dess pulverform) 3Dprintades med hjälp av natriumalginat som bindemedel. Studien var lyckad eftersom MOF:arna erhöll entillämplig form/maktrostruktur samtidigt som materialen bevarade sina inneboende egenskaper efter 3Dprintningen.
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Effect of nanoparticles on human cells from healthy individuals and patients with respiratory diseases.Osman, Ilham F. January 2010 (has links)
Ever increasing applications of nanomaterials (materials with one or more dimension
less than 100 nm) has raised awareness of their potential genotoxicity. They have
unique physico¿chemical properties and so could have unpredictable effects. Zinc oxide
(ZnO) and titanium dioxide (TiO2) are widely used in a number of commercial
products. There are published studies indicating that some forms of these compounds
may be photo-clastogenic in mammalian cells. What has not been investigated before is
the effect of nanoparticles from these compounds in human germ cells. Thus the
present study has examined their effects in the presence and absence of UV light in
human sperm and compared responses to those obtained with human lymphocytes using
the Comet assay to measure DNA damage. The effect of nanoparticles (40-70nm range)
was studied in human sperm and lymphocytes in the dark, after pre-irradiation with UV
and simultaneous irradiation with UV. The studies do provide some evidence that there
are photo-genotoxic events in sperm and lymphocytes in the absence of overt toxicity.
The cytotoxic and genotoxic potentials of ZnO and TiO2 as well as their effect on
phosphotyrosine expression, were examined in the human epithelial cervical carcinoma
cells (Hela cells). This was done to try and determine the underlying molecular events
resulting from their exposure to ZnO and TiO2 nanoparticles occurring at the same time
as DNA is damaged. Concentration- and time-dependent cytotoxicity, and an increase
in DNA and cytogenetic damage with increasing nanoparticle concentrations were
reported in this study. Mainly for zinc oxide, genotoxicity was clearly associated with
an increase in tyrosine phosphorylation.
Nanotechnology has raced ahead of nanotoxicology and little is known of the effects of
nanoparticles in human systems, let alone in diseased individuals. Therefore, the effects
of TiO2 nanoparticles in peripheral blood lymphocytes from patients with respiratory
diseases (lung cancer, chronic obstructive pulmonary disease (COPD) and asthma) were
compared with those in healthy individuals using genotoxic endpoints to determine
whether there are any differences in sensitivity to nano-chemical insult between the
patient and control groups. The results have shown concentration dependent genotoxic
effects of TiO2 in both respiratory patient and control groups in the Comet assay and an
increasing pattern of cytogenetic damage measured in the micronucleus assay without
being statistically significant except when compared with the untreated controls of
healthy individuals. Furthermore, modulation of ras p21 expression was investigated.
Regardless of TiO2 treatment, only lung cancer and COPD patients expressed
measurable ras p21 levels that showed modulation as the result of nanoparticle
treatment.
Results have suggested that both ZnO and TiO2 nanoparticles can be genotoxic over a
range of concentrations without either photoa-ctivation or being cytotoxic.
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Magnetron Sputter Epitaxy of High-quality GaNand Plasma Characterization of the Process : Degree Project–Master’s ThesisLo, Yi-Ling January 2021 (has links)
Several sputtering depositions were done by direct current (DC) magnetron sputtering epitaxy (MSE) techniquefor the goal of improving the growth rate and crystalline quality of GaN thin film on Al2O3 substrate. Thegrowth rate was higher when substrate-to-target distance D = 7 cm compared with D = 9.3 cm with eitherfloating or positive bias on the substrate side. The crystalline quality was improved by raising up the growthtemperature from 700◦C to 900◦C, but the quality was declined from 900◦C to 1000◦C due to strong desorption.Gas composition in the metal mode gives better quality due to its sufficient Ga condition with less N2. Positivesubstrate bias boosted the plasma potential and therefore created higher actual sputtering power comparedwith the condition at floating substrate potential. In general, applying a higher power can elevate the growthrate and film quality. However, there has not been an evident difference of both growth rate and film qualitywhen the actual sputtering power is close for floating substrate potential and positive substrate bias.
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Computational studies of electronic and thermal properties of low dimensional materialsRodriguez Mendez, Alvaro Gaspar 25 October 2023 (has links)
The control of low dimensional materials holds potential for revolutionizing the electronic, thermal, and thermoelectric materials engineering. Through strategic manipulation and optimization of these materials, unique properties can be uncover which enable more efficient and effective materials development. Towards the determination of nanoscale strategies to improve the electronic and phononic devices, computational simulations of modified low dimensional materials have been carried in this research. First, the electronic properties of chemically func tionalized phosphorene monolayers are evaluated with spin-polarized Density Functional Theory, as a potential method to tune their electronic properties.
The functionalization not only leads to formation of additional states within the semiconducting gap, but also to the emergence of local magnetism. The magnetic ground state and electronic structure are investigated in dependence of molecular coverage, lattice direction of the molecular adsorption and molecule type functionalization. Furthermore, the physical and transport properties of phosphorene grain boundaries under uniaxial strain are evaluated by the use of Density Functional based Tight Binding method in combination with Landauer theory. In both grain boundary types, the electronic bandgap decreases under strain, however, the respective thermal conductance is only weakly affected, despite rather strong changes in the frequency-resolved phonon transmission. The combination of both effects results in an enhancement in the thermoelectric figure of merit in the phosphorene grain boundary systems. Finally, the thermoelectric properties of carbon nanotubes peapod heterostructures are studied and compared to pristine nanotubes using also the Density Functional based Tight Binding method and Landauer theory. It is found that the fullerene encapsulation modifies the electron and phonon transport properties, causing the formation of electronic channels and the suppression of vibrational modes that lead to an improvement of the thermoelectric figure of merit. The results of this thesis highlight the potential of strategic manipulation and optimization of low dimensional materials in improving their unique electronic and thermal properties, revealing promising avenues for improving electronic and phononic devices.:ABSTRACT i
ZUSAMMENFASSUNG ii
ACKNOWLEDGEMENT iv
LIST OF FIGURES ix
LIST OF TERMS AND ABBREVIATIONS xviii
1 Introduction 1
1.1 Motivation 1
1.2 Objectives and outline 6
2 Computational Methods 8
2.1 Density Functional Theory 8
2.1.1 The Many-Body System Hamiltonian and the Born-Oppenheimer approximation 9
2.1.2 Thomas-Fermi-Dirac approximation model 10
2.1.3 The Hohenberg-Kohn theorems 12
2.1.4 The Kohn-Sham orbitals equations 13
2.1.5 Exchange-correlation functionals 15
2.2 Density Functional Based Tight Binding method 16
2.2.1 Tight-binding formalism 17
2.2.2 From DFT to DFTB 20
2.2.3 Parametrization 22
2.3 Atomistic Green’s functions 23
2.3.1 Non-Equilibrium Green’s functions for modeling electronic transmission 23
2.3.2 Non-equilibrium Green’s function for modeling thermal transmission 27
3 Tuning the electronic and magnetic properties through chemical functionalization
3.1 Introduction 33
3.1.1 Black phosphorus as a 2D material 33
3.1.2 Chemical Functionalization of low dimensional systems 35
3.1.3 Bipolar Magnetic Semiconductors 36
3.2 Computational approach 38
3.3 Interface effects in phosphorene by OH functionalization 39
3.3.1 Single molecule functionalization 39
3.3.2 Lattice selection 43
3.3.3 Coverage 45
3.4 Chiral functionalization effect in phosphorene 48
3.5 Functionalizing phosphorene towards BMS 51
3.6 Summary 53
4 Tuning transport properties through strain and grain bound-aries
4.1 Introduction 54
4.1.1 Strain in low dimensional materials 54
4.1.2 Grain boundaries 56
4.2 Computational approach 58
4.2.1 Molecular systems 58
4.2.2 Electron and phonon transport and thermoelectric figure of merit 58
4.3 Structural modification by strain in GB systems 60
4.4 Electronic structure modification by strain in GB systems 63
4.5 Thermal transport modification by strain in GB systems 65
4.6 Thermoelectric figure of merit of strained GB systems 68
4.7 Summary 71
5 Tuning transport properties through hybrid nanomaterials: CNT peapods 73
5.1 Introduction 73
5.1.1 Carbon-based nanostructures 73
5.1.2 CNT peapods as hybrid nanomaterials 76
5.2. Computational details 77
5.2.1 CNT peapod model 77
5.2.2 Quantum transport methodology 78
5.3 Structural properties of CNT peapods 79
5.4 Electronic properties of CNT peapods 80
5.5 Thermal properties of CNT peapods 83
5.6 Thermoelectronic properties of CNT peapods 85
5.7 Summary 88
6 Conclusions and outlook 91
Appendices
Appendix A Supplementary information to phosphorene functionalization
A.1 Spin resolved density of states of 1-OH system 96
A.2 Spin valve model 97
Appendix B Supplementary information to phosphorene grain boundaries 98
B.1 Projected Phonon Density of States in GB1 98
B.2 Thermoelectric transport properties of GB2 99
Appendix C Supplementary information to CNT peapods 101
C.1 Geometry optimization of CNT peapods with larger CNT diameter 101
C.2 Additional analysis of electron transport properties 102
C.3 Phonon band structure of different CNT structures 104
C.4 Additional analysis of thermoelectric performance 105
REFERENCES 105
LIST OF PUBLICATIONS 131
PRESENTATIONS 132 / Die Kontrolle niedrigdimensionaler Materialien birgt das Potenzial für eine Revolutionierung der elektronischen, thermischen und thermoelektrischen Technologien. Durch strategische Manipulation und Optimierung dieser Materialien können einzigartige Eigenschaften aufgedeckt werden, die eine effizientere und effektivere Materialentwicklung ermöglichen. Um Strategien im Nanobereich zur Verbesserung elektronischer und phononischer Bauelemente zu ermitteln, wurden in dieser Forschungsarbeit rechnerische Simulationen modifizierter niedrigdimensionaler Materialien durchgeführt. Zunächst werden die elektronischen Eigenschaften von chemisch funktionalisierten Phosphoren-Monoschichten mit Hilfe der spinpolarisierten Dichtefunktionaltheorie als potenzielle Methode zur Abstimmung ihrer elektronischen Eigenschaften bewertet. Die Funktionalisierung führt nicht nur zur Bildung zusätzlicher Zustände innerhalb der halbleitenden Lücke, sondern auch zum Auftreten von lokalem Magnetismus. Der magnetische Grundzustand und die elektronische Struktur werden in Abhängigkeit von der molekularen Bedeckung, der Gitterrichtung der molekularen Adsorption und der Funktionalisierung des Moleküls untersucht. Darüber hinaus werden die Transporteigenschaften von Phosphoren-Korngrenzen unter uniaxialer Belastung
mit Hilfe der auf Dichtefunktionen basierenden Tight-Binding-Methode in Kombination mit der Landauer-Theorie untersucht. In beiden Korngrenzentypen nimmt die elektronische Bandlücke unter Dehnung ab, die jeweilige Wärmeleitfähigkeit wird jedoch nur schwach beeinflusst, trotz ziemlich starker Änderungen in der frequenzaufgelösten Phononentransmission. Die Kombination bei der Effekte führt zu einer Erhöhung der thermoelektrischen Leistungszahl in den Phosphorkorngrenzensystemen. Schließlich werden die thermoelektrischen Eigenschaften von Kohlenstoffnanoröhren-Peapod-Heterostrukturen untersucht und mit denen von reinen Nanoröhren verglichen, wobei auch die auf Dichtefunktionen basierende Tight-Binding-Methode und die Landauer-Theorie verwendet werden. Es wird festgestellt, dass die Fullereneinkapselung die Elektronen- und Phononentransporteigenschaften modifiziert und die Bildung von elektronischen Kanälen und die Unterdrückung von Schwingungsmoden bewirkt, was zu einer Verbesserung der thermoelektrischen Leistungszahl führt. Die Ergebnisse dieser Arbeit verdeutlichen das Potenzial der strategischen Manipulation und Optimierung niedrigdimensionaler Materialien zur Verbesserung ihrer einzigartigen elektronischen und thermischen Eigenschaften und zeigen vielversprechende Wege zur Verbesserung elektronischer und phononischer Bauteile auf.:ABSTRACT i
ZUSAMMENFASSUNG ii
ACKNOWLEDGEMENT iv
LIST OF FIGURES ix
LIST OF TERMS AND ABBREVIATIONS xviii
1 Introduction 1
1.1 Motivation 1
1.2 Objectives and outline 6
2 Computational Methods 8
2.1 Density Functional Theory 8
2.1.1 The Many-Body System Hamiltonian and the Born-Oppenheimer approximation 9
2.1.2 Thomas-Fermi-Dirac approximation model 10
2.1.3 The Hohenberg-Kohn theorems 12
2.1.4 The Kohn-Sham orbitals equations 13
2.1.5 Exchange-correlation functionals 15
2.2 Density Functional Based Tight Binding method 16
2.2.1 Tight-binding formalism 17
2.2.2 From DFT to DFTB 20
2.2.3 Parametrization 22
2.3 Atomistic Green’s functions 23
2.3.1 Non-Equilibrium Green’s functions for modeling electronic transmission 23
2.3.2 Non-equilibrium Green’s function for modeling thermal transmission 27
3 Tuning the electronic and magnetic properties through chemical functionalization
3.1 Introduction 33
3.1.1 Black phosphorus as a 2D material 33
3.1.2 Chemical Functionalization of low dimensional systems 35
3.1.3 Bipolar Magnetic Semiconductors 36
3.2 Computational approach 38
3.3 Interface effects in phosphorene by OH functionalization 39
3.3.1 Single molecule functionalization 39
3.3.2 Lattice selection 43
3.3.3 Coverage 45
3.4 Chiral functionalization effect in phosphorene 48
3.5 Functionalizing phosphorene towards BMS 51
3.6 Summary 53
4 Tuning transport properties through strain and grain bound-aries
4.1 Introduction 54
4.1.1 Strain in low dimensional materials 54
4.1.2 Grain boundaries 56
4.2 Computational approach 58
4.2.1 Molecular systems 58
4.2.2 Electron and phonon transport and thermoelectric figure of merit 58
4.3 Structural modification by strain in GB systems 60
4.4 Electronic structure modification by strain in GB systems 63
4.5 Thermal transport modification by strain in GB systems 65
4.6 Thermoelectric figure of merit of strained GB systems 68
4.7 Summary 71
5 Tuning transport properties through hybrid nanomaterials: CNT peapods 73
5.1 Introduction 73
5.1.1 Carbon-based nanostructures 73
5.1.2 CNT peapods as hybrid nanomaterials 76
5.2. Computational details 77
5.2.1 CNT peapod model 77
5.2.2 Quantum transport methodology 78
5.3 Structural properties of CNT peapods 79
5.4 Electronic properties of CNT peapods 80
5.5 Thermal properties of CNT peapods 83
5.6 Thermoelectronic properties of CNT peapods 85
5.7 Summary 88
6 Conclusions and outlook 91
Appendices
Appendix A Supplementary information to phosphorene functionalization
A.1 Spin resolved density of states of 1-OH system 96
A.2 Spin valve model 97
Appendix B Supplementary information to phosphorene grain boundaries 98
B.1 Projected Phonon Density of States in GB1 98
B.2 Thermoelectric transport properties of GB2 99
Appendix C Supplementary information to CNT peapods 101
C.1 Geometry optimization of CNT peapods with larger CNT diameter 101
C.2 Additional analysis of electron transport properties 102
C.3 Phonon band structure of different CNT structures 104
C.4 Additional analysis of thermoelectric performance 105
REFERENCES 105
LIST OF PUBLICATIONS 131
PRESENTATIONS 132
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Thermal Conductivity and Mechanical Properties of Interlayer-Bonded Graphene BilayersMostafa, Afnan 14 November 2023 (has links) (PDF)
Graphene, an allotrope of carbon, has demonstrated exceptional mechanical, thermal, electronic, and optical properties. Complementary to such innate properties, structural modification through chemical functionalization or defect engineering can significantly enhance the properties and functionality of graphene and its derivatives. Hence, understanding structure-property relationships in graphene-based metamaterials has garnered much attention in recent years. In this thesis, we present molecular dynamics studies aimed at elucidating structure-property relationships that govern the thermomechanical response of interlayer-bonded graphene bilayers.
First, we present a systematic and thorough analysis of thermal transport in interlayer-bonded twisted bilayer graphene (IB-TBG). We find that the introduction of interlayer C-C bonds in these bilayer structures causes an abrupt drop in the in-plane thermal conductivity of pristine, non-interlayer-bonded bilayer graphene, while further increase in the interlayer C-C bond density (2D diamond fraction) leads to a monotonic increase in the in-plane thermal conductivity of the resulting superstructures approaching the high in-plane thermal conductivity of 2D diamond (diamane). We also find a similar trend in the in-plane thermal conductivity of interlayer-bonded graphene bilayers with randomly distributed individual interlayer C-C bonds (RD-IBGs) as a function of interlayer C-C bond density, but with the in-plane thermal conductivity of the IB-TBG 2D diamond superstructures consistently exceeding that of RD-IBGs at a given interlayer bond density. We analyze the simulation results employing effective medium and percolation theories and explain the predicted dependence of in-plane thermal conductivity on interlayer bond density on the basis of lattice distortions induced in the bilayer structures as a result of interlayer bonding. Our findings demonstrate that the in-plane thermal conductivity of IB-TBG 2D diamond superstructures and RD-IBGs can be precisely tuned by controlling interlayer C-C bond density with important implications for the thermal management applications of interlayer-bonded few-layer graphene derivatives.
Secondly, we report results on the mechanical and structural response to shear deformation of nanodiamond superstructures in interlayer-bonded twisted bilayer graphene (IB-TBG) and interlayer-bonded graphene bilayers with randomly distributed individual interlayer C-C bonds (RD-IBGs). We find that IB-TBG nanodiamond superstructures subjected to shear deformation undergo a brittle-to-ductile transition (BDT) with increasing interlayer bond density (nanodiamond fraction). However, RD-IBG bilayer sheets upon shear deformation consistently undergo brittle failure without exhibiting a BDT. We identify, explain, and characterize in atomic-level detail the different failure mechanisms of the above bilayer structures. We also report the dependence of the mechanical properties, such as shear strength, crack initiation strain, toughness, and shear modulus, of these graphene bilayer sheets on their interlayer bond density and find that these properties differ significantly between IB-TBG nanodiamond superstructures and RD-IBG sheets. Our findings show that the mechanical properties of interlayer-bonded bilayer graphene sheets, including their ductility and the type of failure they undergo under shear deformation, can be systematically tailored by controlling interlayer bond density and distribution. These findings contribute significantly to our understanding of these 2D graphene-based materials as mechanical metamaterials.
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AI Trained to Predict Thresholds of 2D Ellipse Percolation Systems / AI utbildad för att förutsäga 2D homogen och heterogen ellipspercolationSurajlal, Nirav January 2021 (has links)
Percolation theory is a relevant area of research in Nanotechnology because of its wide applications in nanoelectronics based on thin films of nanoparticles and composites, amongst others. In nanotechnology, systems are often explored through modelling and simulations. Thin films of the emerging low-dimensional nanomaterials, such as the 1D nanowires/nanotubes and 2D graphene, as well as their composites, can generally be simulated through a two dimensional percolation system of homogeneous or heterogeneous ellipses. The critical phenomena, i.e., the percolation threshold of the systems, is now obtained using the Monte Carlo simulation method, which, need extensive amounts of time. This project is an interdisciplinary one, wherein an attempt is made to use a certain amount of the data from the Monte Carlo simulations to train a machine learning model to predict the threshold of all the 2D ellipse systems with the maximum relative error < 10%, thus reducing the time taken when gathering the data. This project investigates different algorithms such as Linear Regression, Polynomial Regression, Multi-layer Perceptron Neural Networks, Random Forests, Extreme Gradient Boosted Trees, Support Vector Machines and K-Nearest Neighbours. Weaknesses in the results are identified and overcome by specific additional sample generation. Finally, a comparison is made between the algorithms marking the Multi-layer Perceptron and Extreme Gradient Boosted Trees as successful, with the Multi-layer Perceptron being the clear winner. The algorithm is successful within the defined 10% relative error, performing even better with all samples having relative prediction errors less than 7%. The model can be downloaded and used from https://github.com/NiravSurajlal/ PercolationAI. / Perkolationsteori är ett relevant forskningsområde inom nanoteknik på grund av dess breda tillämpningar inom nanoelektronik, bland annat baserade på tunna filmer av nanopartiklar och kompositer. Inom nanoteknik undersöks system ofta genom modellering och simuleringar. Tunna filmer av de framväxande lågdimensionella nanomaterialen, såsom 1D-nanotrådar / nanorör och 2Dgrafen, liksom deras kompositer, kan i allmänhet simuleras genom ett tvådimensionellt perkolationssystem av homogena eller heterogena ellipser. De kritiska fenomenen, dvs. systemets perkolationströskel, erhålls nu med hjälp av Monte Carlosimuleringsmetoden, som kräver omfattande tidsperioder. Detta projekt är ett tvärvetenskapligt projekt, där man försöker använda en viss mängd data från Monte Carlo-simuleringarna för att träna en maskininlärningsmodell för att förutsäga tröskeln för alla 2D-ellipssystem med det maximala relativa felet <10%vilket minskar den tid det tar att samla in data. Detta projekt undersöker olika algoritmer som linjär regression, polynomregression, flerlagers Perceptron-neuronnätverk, slumpmässiga skogar, extrema gradientförstärkta träd, stöd för vektormaskiner och K-närmaste grannar. Svagheter i resultaten identifieras och övervinns genom specifik ytterligare provgenerering. Slutligen görs en jämförelse mellan algoritmerna som markerar Multi-layer Perceptron och Extreme Gradient Boosted Trees som framgångsrika, med Multi-layer Perceptron som den tydliga vinnaren. Algoritmen är framgångsrik inom det definierade 10 % relativfelet och presterar ännu bättre med alla prover som har relativa prediktionsfel mindre än 7 %. Modellen kan laddas ner och användas från https://github.com/NiravSurajlal/PercolationAI.
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Effects of Graphene Oxide in vitro on DNA Damage in Human Whole Blood and Peripheral Blood Lymphocytes from Healthy individuals and Pulmonary Disease Patients: Asthma, COPD, and Lung CancerAmadi, Emmanuel E. January 2019 (has links)
For the past few decades, the popularity of graphene oxide (GO) nanomaterials
(NMs) has increased exceedingly due to their biomedical applications in drug
delivery of anti-cancer drugs. Their unique physicochemical properties such as
high surface area and good surface chemistry with unbound surface functional
groups (e.g. hydroxyl - OH, carboxyl /ketone C=O, epoxy/alkoxy C-O, aromatic
group C=C, etc) which enable covalent bonding with organic molecules (e.g.
RNA, DNA) make GO NMs as excellent candidates in drug delivery nanocarriers.
Despite the overwhelming biomedical applications, there are concerns about their
genotoxicity on human DNA. Published genotoxicity studies on GO NMs were
performed using non-commercial GO with 2-3 layers of GO sheets, synthesized
in various laboratories with the potential for inter-laboratory variabilities. However,
what has not been studied before is the effects of the commercial GO (15-20
sheets; 4-10% edge-oxidized; 1 mg/mL) in vitro on DNA damage in human whole
blood and peripheral blood lymphocytes (PBL) from real-life patients diagnosed
with chronic pulmonary diseases [asthma, chronic obstructive pulmonary disease
(COPD), and lung cancer], and genotoxic endpoints compared with those from
healthy control individuals to determine whether there are any differences in GO
sensitivity. Thus, in the present study, we had characterized GO NMs using
Zetasizer Nano for Dynamic Light Scattering (DLS) and zeta potential (ZP) in the
aqueous solution, and electron microscopy using the Scanning Electron
Microscope (SEM) and Transmission Electron Microscope (TEM) in the dry state,
respectively. Cytotoxicity studies were conducted on human PBL from healthy
individuals and patients (asthma, COPD, and lung cancer) using the
Methylthiazolyldiphenyl-tetrazolium bromide (MTT) and Neutral Red Uptake
(NRU) assays, respectively. The genotoxicity (DNA damage) and cytogenetic
effects (chromosome aberration parameters) induced by GO NMs on human
whole blood from healthy individuals and patients were studied using the Alkaline
Comet Assay and Cytokinesis-blocked Micronucleus (CBMN) assay,
respectively. Our results showed concentration-dependent increases in
cytotoxicity, genotoxicity, and chromosome aberrations, with blood samples from
COPD and lung cancer patients being more sensitive to DNA damage insults
compared with asthma patients and healthy control individuals. Furthermore, the
relative gene and protein expressions of TP53, CDKN1A/p21, and BCL-2 relative
to GAPDH on human PBL were studied using the Reverse Transcription
Quantitative Polymerase Chain Reaction (RT-qPCR) and Western Blot
techniques, respectively. Our results have shown altered gene and protein
expression levels. Specifically, GO-induced cytotoxicity, genotoxicity, and
micronuclei aberrations were associated with TP53 upregulation - a biomarker of
DNA damage - in both patients and healthy individuals. These effects show that
GO NMs have promising roles in drug delivery applications when formulated to
deliver drug payload to COPD and cancer cells. However, the fact that cytotoxicity, genotoxicity, chromosome instability, and gene/protein expressions
- biomarkers of cancer risk - were observed in healthy individuals are of concern
to public health, especially in occupational exposures at micro levels at the
workplace.
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Development of an Artificial Nose for the Study of Nanomaterials Deposition in Nasal Olfactory RegionYerich, Andrew J. 29 November 2017 (has links)
No description available.
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Synthesis, adsorption and structural properties of carbons with uniform and ordered mesoporesGierszal, Kamil Piotr 09 April 2008 (has links)
No description available.
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CONTROLLED FUNCTIONALIZATION AND ASSEMBLY OF GRAPHENE NANOSTRUCTURES FOR SENSING AND ENERGY STORAGENagelli, Enoch A. 02 September 2014 (has links)
No description available.
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