Investigation of the chemical vapor deposition of Cu from copper amidinate through data driven efficient CFD modelling

peer reviewedA chemical reaction model, consisting of two gas-phase and a surface reaction, for the deposition of copper from copper amidinate is investigated, by comparing results of an efficient, reduced order CFD model with experiments. The film deposition rate over a wide range of temperatures, 473K-623K, is accurately captured, focusing specifically on the reported drop of the deposition rate at higher temperatures, i.e above 553K that has not been widely explored in the literature. This investigation is facilitated by an efficient computational tool that merges equation-based analysis with data-driven reduced order modeling and artificial neural networks. The hybrid computer-aided approach is necessary in order to address, in a reasonable time-frame, the complex chemical and physical phenomena developed in a three-dimensional geometry that corresponds to the experimental set-up. It is through this comparison between the experiments and the derived simulation results, enabled by machine-learning algorithms that the prevalent theoretical hypothesis is tested and validated, illuminating the possible underlying dominant phenomena

Scalable Nano Particle Production of Low Bioavailability Pharmaceuticals for Augmented Aqueous Solubility

The billion dollar pharmaceutical research and development pipeline suffers greatly from high attrition rates of novel therapeutic compounds within pre-clinical and clinical trials. Poor bioavailability in many new drugs, originating in the various methodologies of high throughput screening, may explain part of these growing failure rates. One interpretation of this phenomenon relies on bioavailability\u27s correlation with aqueous solubility; much modern processing allows chemicals to fully develop without touching water, yielding upwards of 90% of new chemical entities practically insoluble in aqueous media. Thus, one approach to alleviating bioavailability and potentially clinical attrition rates necessitates augmented aqueous solubility. The amorphous nanoparticle presents the largest boost in aqueous solubility of a chemical through processing alone. In this contribution, we propose electrospray as a novel, competitive candidate to produce pharmaceutical amorphous nanoparticles with the intent of augmenting solubility. Electrospray represents an idyllic nominee for three reasons: repeatability, flexibility, and scalability. Electrospray offers low batch to batch variation with less than 30% relative standard deviation between various droplets. This triumphs over the several orders of magnitude in variation in pneumatic sprays. Electrospray\u27s flexibility draws from its ability to attain diameters over several orders of magnitude, ranging from hundreds of microns to several nanometers; in this contribution droplets are produced between 500 nm and 1[micro]m. Finally, electrospray displays scalability to any industrial requirement; though a single nozzle operates at mere microliters per hour, a single multiplexed array of emitters may increase this throughput by several orders of magnitude. This exploration, utilizing Indomethacin as a model low solubility chemical, verifies electrospray as a compatible processing tool for the pharmaceutical industry. Scanning electron microscopy coupled with the image analysis software ImageJ gleans the size and shape of emitted (and dried) particles. Amorphicity verification of particles employs grazing angle x-ray diffraction. Finally, ultraviolet and visual spectrum spectroscopy evaluates the solubility advantage of particles

NUCLEATION AND DETECTION IN TENSION METASTABLE FLUIDS

Neutron detection and spectroscopic techniques using state-of-the-art systems is covered. A novel approach using conventional (e.g., LiI, He-3, BF3) detectors coupled with Monte-Carlo code simulations to develop spectroscopy information was developed (in lieu of present-day tedious methods involving data acquisition using a multi-sized set of Bonner spheres). Focus of this thesis work was on developing neutron spectroscopy and multiplicity technology using the underlying science of tensioned metastable fluid detectors (TMFDs) in which neutron radiation interactions with atoms of TMFD fluids cause onset of cavitation bubbles. There are many applications and areas of science that would benefit from an increased knowledge about the relationship between the conditions and states of a metastable liquid and the appearance of cavitation bubbles due to ionizing radiation. One specific area that benefits significantly is the application of such knowledge to TMFDs, which already boast demonstrated and impressive advantages over traditional detection systems with sensitivity over 8 orders of magnitude in neutron energy, 90% intrinsic neutron detection efficiency (in optimal geometry), complete insensitivity to gamma radiation when operating in a neutron detection mode, ~100% sensitivity to dissolved alpha emitters and fission decays, directional information and potentially orders of magnitude reduced cost

Deconstructing the glass transition through critical experiments on colloids

The glass transition is the most enduring grand-challenge problem in contemporary condensed matter physics. Here, we review the contribution of colloid experiments to our understanding of this problem. First, we briefly outline the success of colloidal systems in yielding microscopic insights into a wide range of condensed matter phenomena. In the context of the glass transition, we demonstrate their utility in revealing the nature of spatial and temporal dynamical heterogeneity. We then discuss the evidence from colloid experiments in favor of various theories of glass formation that has accumulated over the last two decades. In the next section, we expound on the recent paradigm shift in colloid experiments from an exploratory approach to a critical one aimed at distinguishing between predictions of competing frameworks. We demonstrate how this critical approach is aided by the discovery of novel dynamical crossovers within the range accessible to colloid experiments. We also highlight the impact of alternate routes to glass formation such as random pinning, trajectory space phase transitions and replica coupling on current and future research on the glass transition. We conclude our review by listing some key open challenges in glass physics such as the comparison of growing static lengthscales and the preparation of ultrastable glasses, that can be addressed using colloid experiments.Comment: 137 pages, 45 figure

Flame-Formed Carbon Nanoparticles: Synthesis and characterization

Nanoparticles and nanostructured materials characterize an increasing research area, gaining strong attention from the scientific community in several fields. During the last decades, many and extraordinary technological advances have been obtained by nano-materials due to their physicochemical properties. In nature, at micro- and nano-scale, materials have existed for a long time before, but it is only through the advent of the technological era, and consequently, the development of nanotechnology, that they have come to the fore. There are several forms of nanoparticles: metal-based, organic-based or organic/inorganic combination and carbon-based ones. Carbon nanoparticles are the most widely studied as carbon is suitable and available raw material. Except for hydrogen, carbon has the most significant number of known compounds and is present on the planet in various forms: from carbon to light and heavy hydrocarbons. Carbon-based nanoparticles have shown a wide variety of structural arrangements that make them a great advantage as they are suitable for various purposes. Several techniques exist to cope with the production of the nano-size materials in both liquid and gas phase; examples are arc-discharge, laser ablation, chemical vapour deposition. The more the process allows to have a production (functional to specific final characteristics of the material) on a large scale and in an economical way, the more it is taken into consideration and studied. Among the various techniques, the use of flame and, therefore, combustion technology is increasingly taken into consideration. Traditionally, combustion is associated with the study of particulate matter and undesired products released into the atmosphere daily to understand the onset of their formation and reduce, if not abate, their emissions. Nevertheless, on the other hand, flame-formed carbon nanoparticles have been the subject of increasing interest in recent decades as a new procedure for synthesizing engineered nanoparticles. In order to obtain flame nanoparticles with desired characteristics and with the highest yield, it is necessary to have an in-depth knowledge of their formation process through the reaction system, the flame. It is necessary to delve into the chemical and physical details of the various steps of the mechanism that lead to the final product; pay attention to the inherent characteristics of the particles, such as size distribution, chemical composition, and physical characteristics. Moreover, depending on the final product to be obtained, flames can be modulated and varied in parameters such as temperature, residence time, mixing effect, and the fuel or additive structure. This PhD thesis focuses on studying and characterizing the carbon nanoparticles synthesized in the well-controlled combustion conditions of premixed fuel-rich flame, using a lab-scale reactor constituted by flat laminar ethylene/air premixed flame. The primary purpose of this activity has been to perform an experimental study on flame-formed carbon nanoparticles, with great attention on the still too unclear step of particle formation in flame, i.e. the nucleation. The first year of the PhD was primarily centred on the study and preliminary characterization of physicochemical evolution of flame-formed carbon nanoparticles. In order to produce different sizes of particles, carbon nanoparticles were collected at different distances from the flame front, i.e., the residence time in the flame was changed. Then, various techniques were used to characterize the produced particles. One of the first investigations was performed in the flame by the on-line differential mobility analyzer to study the particle size distribution. Subsequently, the analytical tools continued with ex-situ techniques such as Raman spectroscopy and Electron Paramagnetic Resonance, the former for chemical and structural information on particles modification and the latter to reveal and confirm the presence of radicals and to identify them. In this thesis, great attention was laid on the presence and role of radical species, above all, in the determining step of nucleation. For this reason, the research continued in the second year with a more detailed analysis of radical formation in the flame products mechanism and a more specific structural characterization of carbon nanoparticles. Indeed, a density functional theory study investigated some aspects related to the behaviour of radical molecules in flame in terms of dimerization and formation of cluster structures. Notably, the study was helpful in the differentiation between - and -radicals. Following the theoretical evaluation of the radical molecules, the question was raised about how such radicals could form, i.e., whether specific structural elements could facilitate their formation and, consequently, direct carbon particles' formation through a specific mechanism. This type of structural investigation was performed through the Proton Nuclear Resonance Spectroscopy ,1H-NMR; for the first time used in a system such as the one studied in this thesis work. Then, in the third and final year of this PhD research work, a comparative physicochemical evolution study in an aromatic fuel environment has been performed. The addition of an aromatic dopant, such as benzene, leads to some change in the flame and the particle formation in terms of particles size distribution, Raman features, and especially radical production, allowing to face up the same questions in such environment and to investigate the effect of aromatic fuel on the nature and the role of radicals in particle nucleation and growth

From partial data to out-of-sample parameter and observation estimation with diffusion maps and geometric harmonics

peer reviewedA data-driven framework is presented, that enables the prediction of quantities, either observations or parameters, given sufficient partial data. The framework is illustrated via a computational model of the deposition of Cu in a Chemical Vapor Deposition (CVD) reactor, where the reactor pressure, the deposition temperature and feed mass flow rate are important process parameters that determine the outcome of the process. The sampled observations are high-dimensional vectors containing the outputs of a detailed CFD steady-state model of the process, i.e. the values of velocity, pressure, temperature, and species mass fractions at each point in the discretization. A machine learning workflow is presented, able to predict out-of-sample (a) observations (e.g. mass fraction in the reactor), given process parameters (e.g. inlet temperature); (b) process parameters, given observation data; and (c) partial observations (e.g. temperature in the reactor), given other partial observations (e.g. mass fraction in the reactor). The proposed workflow relies on two manifold learning schemes: Diffusion Maps and the associated Geometric Harmonics. Diffusion Maps are used for discovering a reduced representation of the available data, and Geometric Harmonics for extending functions defined on the discovered manifold. In our work a special use case of Geometric Harmonics is formulated and implemented, which we call Double Diffusion Maps, to map from the reduced representation back to (partial) observations and process parameters. A comparison of our manifold learning scheme to the traditional Gappy-POD approach is provided: ours can be thought of as a “Gappy DMAPs” approach. The presented methodology is easily transferable to application domains beyond reactor engineering

Ferramenta de apoio para a aplicação de nanoengenharia no desenvolvimento de processos de fabrico eco-eficientes

The aim of this work is to present the NanoTechnology Usability (NTU) index tool, created and developed in order to reduce the gap between nanotechnologybased products developed in R & D centers and their effective application and utilization, promoting the optimized selection of materials and the use of ecoefficient production techniques. In this sense, the doctoral work contextualizes the current market of the types of commercially available nanomaterials, the most used synthesis methods, their current and potential market applications, current standards, obstacles and uncertainties with regard to the production, manipulation and assembling of nano-based products. Existing models and tools currently in the market, particularly that address ecodesign and nanotechnology, are also presented. Based on the diversity of the nano-based product, specific application, maturity level, type of nanomaterials used and synthesis methods, the NTU is applied to four case studies for further discussion and analysis of the results.O presente trabalho propõe-se a apresentar a ferramenta índice de utilização de nanotecnologia (NTU) criada e desenvolvida com o intuito de diminuir o hiato existente entre os produtos baseados em nanotecnologia desenvolvidos nos centros de I&D e a sua aplicação e utilização efetiva, promovendo a seleção otimizada dos materiais e a utilização de técnicas de produção eco-eficientes. Desta forma, o trabalho de doutoramento contextualiza o mercado atual dos tipos de nanomateriais disponíveis comercialmente, os métodos de síntese mais utilizados, as suas aplicações atuais e potenciais no mercado, as normas vigentes, os obstáculos e incertezas no que diz respeito à produção, manipulação e assemblagem de produtos baseados em nanotecnologia. Os modelos e ferramentas existentes atualmente, em particular, que endereçam o ecodesign e nanotecnologia são também apresentados. Baseado na diversidade no que concerne o tipo de produto baseado em nanotecnologia, aplicação específica, nível de maturidade, nanomateriais usados e método de síntese, o NTU é aplicado a quatro casos de estudo para sua discussão e análise de resultados.Programa Doutoral em Engenharia Mecânic

University of Nevada, Las Vegas Transmutation Research Program Annual Progress Report Academic Year 2007-2008

It is my pleasure to present the UNLV Transmutation Research Program’s seventh annual report that highlights the academic year 2007-2008. Supporting this document are the many technical reports and theses that have been generated over the past seven years. In the seventh year of our program, we continued to see growth in the Radiochemistry Ph.D. program with a total of 20 students in the fourth year of the program (we anticipated twelve in the program proposal). Since our inception, the program has sponsored to their conclusion 48 M.S. and 6 Ph.D. degrees. The program supported 53 graduate students, 11 undergraduates, and eight post-doctoral scholars in eight academic departments across the UNLV scientific and engineering communities in the academic year 2007-2008. Our research tasks span the range of technology areas for transmutation, including separation of actinides from spent nuclear fuel, methods of fuel fabrication, reactoraccelerator coupled experiments, corrosion of materials exposed to lead-bismuth eutectic, and special nuclear materials protection and accountability. We continued our emphasis on molten metal technology and actinide chemistry in our enhancements to UNLV this year to build a foundation in areas that are in line with UNLV’s strategic growth and our ability to address student-appropriate research in the transmutation program

Survival, Recovery, and Inactivation of Human Norovirus Surrogates, Feline Calicivirus and Murine Norovirus, on Carpets

Worldwide, enteric viruses are the main cause of acute gastroenteritis (AGE). Among these viruses, human noroviruses (HuNoV) are leading cause of AGE and account for ca. 20% of all diarrheal cases, a top-five cause of death worldwide. In humans, these viruses spread via person-to-person contact, food, water, and/or the environment. Person-to-person contact is the most common mode of HuNoV transmission. Yet, environmental transmission has been linked to several outbreaks and prolonged others. HuNoV survival and inactivation on hard environmental surfaces have been extensively studied. However, nonlaunderable soft surfaces, such as carpet, have received little attention despite epidemiological evidence suggesting their role in transfer and transmission of HuNoV. Currently there are no commercially available products for sanitizing these surface after a contamination event. Documenting the efficacy of sanitizers intended for virally contaminated soft surfaces is also compounded by no standardized method for the recovery of viruses. Therefore our aims for this study, using the environmentally relevant soft surface, carpet, were to (i) determine factors that influence the survival and inactivation of enteric viruses on nonlaunderable soft surfaces (ii) determine survival of HuNoV surrogates on an carpet, (iii) compare sampling methods to determine their ability to recover HuNoV surrogates from carpet, and (iv) to assess two sanitizing technologies, silver dihydrogen citrate (SDC) and steam vapor, against a HuNoV surrogate, FCV, on carpet. A systematic review of the literature was conducted to determine factors that influence the survival and inactivation of enteric viruses on nonlaunderable soft surfaces. EBSCO and Web of Science were searched for experimental studies published between 1965 and 2015 using Preferred Reporting Items for Systematic Reviews and Meta-Analyses methods. Titles and abstracts were screened using 3 eligibility criteria. The quality of all study methods was also assessed. Our search yielded 12 articles. Viruses survived between 0 hours and 140 days depending on surface and environment conditions. Virus survival was influenced by temperature, relative humidity, organic content, and deposition method. A variety of chemistries were tested across studies and were shown to have a varied effect on enteric viruses. Chlorine, glutaraldehyde, vaporous ozone, and hydrogen peroxide were the most efficacious against enteric viruses (\u3e 3-log reduction). The efficacy of liquid and vaporous chemistries are associated with surface and virus type The survival profile of HuNoV surrogates, FCV and murine norovirus (MNV), as studied on carpet. First, we measured the zeta potential and absorption capacity of wool and nylon carpet fibers, developed a mini-spin column elution method (MSC), and characterized the survival of HuNoV surrogates, FCV and MNV over 60 days under 30 and 70% relative humidity (RH) on carpets and a glass surface. Carpet surface charge was negative at a typical buffer pH while wool could absorb ca. 2X more liquid than nylon. Percent recovery efficiency with the MSC ranged from 4.34 to 20.89% and 30.71 to 54.14% for FCV and MNV on carpet fibers, respectively. Moreover, elution buffer type did not significantly affect recovery of either surrogate virus. Infectious FCV or MNV survived between \u3c1 and 15 or 3 and 15 days, respectively. However, MNV survived longer under some conditions and at significantly higher titers compared to FCV. Albeit, surrogates followed similar survival trends, i.e. both survived longest on wool followed by nylon and glass while 30% RH provided a more hospitable environment compared to 70% RH. qRT-PCR signals for both surrogates were detectable for the entire study but FCV genomic copies experienced significantly higher reductions (\u3c3.80 log10 copies) on all surfaces compared to MNV (\u3c1.10 log10 copies). Virus recovery methods were compared to evaluate their ability to recover FCV and MNV from carpet. Specifically, we assessed and compared three recovery methods, i.e. bottle extraction (BE), macrofoam-tipped swabbing (MS), and the microbial vacuum (MVAC), using HuNoV surrogates, FCV and MNV, inoculated on wool and nylon. We also investigated detection issues for FCV after environmental recovery, i.e. inhibition. Infectious FCV and MNV percent recovery efficiency (% RE) of BE ranged from 0.44 to 48.44 and 40.77 to 68.83%, respectively, compared to MS % RE, which was 0.02 to 0.82% and 1.54 to 2.87%, respectively. The MVAC % RE of infectious FCV and MNV ranged from 7.30 to 18.29% and 52.58 to 74.67%, respectively. Percent RE of genomic copies of FCV and MNV with BE ranged from 0.36 to 2.53% and 3.34 to 14.97%, respectively, while MS % RE ranged from 1.03 to 2.24 and 2.02 to 4.25%, respectively. The MVAC % RE of genomic copies of FCV and MNV ranged from 2.49 to 23.72% and 28.78 to 79.15%, respectively. Significantly more plaque-forming units and genomic copies were recovered using BE and MVAC compared to MS, while buffer type played a significant role in recovery of infectious FCV. Additionally, qRT-PCR analysis indicated recovery from tested carpet types inhibited amplification of FCV RNA and required dilution after nucleic acid extraction Two sanitizing technologies, SDC and steam vapor, were evaluated against FCV on wool and nylon carpet carriers. First, we evaluated both technologies effect on aesthetic appearance on carpet, developed a neutralizer for SDC, evaluated SDC’s efficacy in suspension with and without 5% fetal bovine serum (FBS), SDC and steam vapor’s efficacy on glass, each with and without 5% FBS, and finally tested both sanitizers on carpets. Wool and nylon carpet carriers exhibit no obvious color changes or abrasions after both treatments, however SDC treatment left a residue while steam left minor abrasions to the surface fibers. A sodium thioglycolate-based solution was found to adequately neutralize and eliminate SDC cytotoxicity. SDC in suspension and on glass reduced FCV by 4.65 and \u3e4.66 log10 pfu, respectively, but demonstrated reduced efficacy in the presence of serum. However, SDC was only efficacious against FCV on nylon (3.62 log10 pfu reduction). Steam vapor reduced FCV by \u3e4.93 log10 pfu on glass in 10 sec, with no observed difference among serum treatments, and \u3e3.68 log10 pfu on wool and nylon carpet carriers in 90 sec. There was limited reduction to FCV RNA under both sanitizer treatments, but RNA reductions were higher in treatments with serum. In this Ph.D. dissertation, I characterized wool and nylon carpet fibers based on their absorptive capacity and zeta potential while demonstrating that HuNoV surrogates, feline calicivirus (FCV) and murine norovirus (MNV), can survive for at least 15 days on carpets under some conditions. Additionally, we evaluated three methods’ recovery efficiency with FCV and MNV on wool and nylon carpets that provides key data and analysis of methods intended for efficacy testing and environmental monitoring. Finally, we assessed two sanitizing technologies, silver dihydrogen citrate (SDC) and steam-vapor with thermo-accelerated nano-crystal sanitation (TANCS) technology, against FCV, in suspension, glass, and wool and nylon carpet carriers of an experimental design for assessing efficacy of sanitizer intended for viruses on carpets. Results suggest SDC and steam-vapor with TANCS are efficacious against FCV but steam-vapor provides the highest level of inactivation. Ultimately, this is the first comprehensive study of HuNoV on carpet, an understudied fomite. Specifically, these studies estimate the survival characteristic of HuNoV on carpet, provide a comprehensive comparison of potential virus recovery methods from carpet, demonstrate the efficacy of two acceptable and reasonable virucidal sanitizers on carpet, and establish a much-needed experimental design for assessing virucidal sani tizers on carpets

Characterization of Nano-Environments by Hypervelocity Projectile Secondary Ion Mass Spectrometry

The purpose of this study was to explore the performance of a secondary ion mass spectrometry (SIMS) technique for probing nanovolumes. The variant of SIMS used involves bombardment with individual massive projectiles (Au400 and C60) at ∼ 1 keV/atom energy coupled with separate recording of the ionized ejecta from each projectile impact. Under these conditions of event-by-event bombardment/detection, each projectile acts as a nanoprobe and secondary ion emission is from an area of 10-15 nm in diameter and a depth of up to 10 nm. The data from ∼ 1x106 impacts can be searched for a specific ion or ions and their coemitted species, revealing the molecular environment around a selected moiety. The methodology was applied to study the coverage of surfactant coatings on gold nanorods. The presented study adds a new instrumental technique for the determination of nanoparticle coverage to this discussion. While nanorod surface density is ∼ 50%, the analysis shows that solvent washing of the nanorods does not result in the removal of the surfactant coating where coverage remains at ∼ 90%. SIMS in the event-by-event bombardment/detection mode displays its promise as an analytical technique due to ease of sample preparation and drastically reduced sample requirements. The ability to probe chemical homogeneity at the nano level allows for the characterization of the chemical environment around nanoparticles. Ultra-small gold nanoparticles, with only 55 to 225 atoms, were encapsulated in a dendrimer structure and analyzed. The comparison of mass spectra of these samples shows that the secondary ion yield of Au moieties vary linearly with the number of Au atoms. Preferential colocation of the nanoparticles and undamaged dendrimer structure was observed, while reductively damaged dendrimer branches are shown be segregated from the nanoparticles. The preference of colocation opens new possibilities for the directed growth of gold nanoparticles within a support structure. The interaction of carbon delivered by hypervelocity projectiles and impacted surfaces was also studied as an analogue to micrometeorite impacts. First, the difference between crystalline and condensed film samples were investigated, determining that secondary ion emission from pressed powders is enhanced over samples produced through vapor deposition. The bombardment with isotopically labeled 13^C60 on inorganic powders enabled the study of recombination products. Here, recombination CN and CNO ions are produced but only CN shows increasing production with higher impact velocities. The study of the interaction of hypervelocity nanoparticles with a 2D material and ultra-thin targets (single layer graphene, multi-layer graphene, and amorphous carbon foils) has been performed using Au4+ 400. The ejected area is much larger (∼60 nm2 ) than that predicted by molecular dynamic simulations and a large ionization rate (∼1%) is observed. The interaction proceeds in an entirely different manner for the process in 3D materials. The experimental observations indicate at least four different emission processes for the observed secondary ions: direct interaction with the projectile which produces high kinetic energy secondary ions in the transmission direction; emission of high velocity secondary ions from the rim of the rupture; emission of H+ n and C+ due to a high charge around the rupture; and emission of low velocity carbon clusters due to a propagation of tears and defects in the graphene foil