1,720,957 research outputs found
Nanofiber Fabrication and Applications: Direct Contact Water Desalination & Energy Harvesting
No full textCompared to conventional structures, nanofibers have lightweight, excellent mechanical properties, controllable pore structures, and high surface to volume ratio. These properties make them ideal for filtration, sensor generation, tissue engineering, functional materials, and energy harvesting and storage like applications. Poly (vinylidene fluoride) (PVDF) polymer possesses the highest electromechanical responses over a broad temperature range, among other possible materials for nanofiber formation. Among all the fabrication techniques, electrospinning is the most widely used method due to its unique advantages like high surface to volume ratio, adjustable porosity of the fibers, and the flexibility to electrospin into a variety of shapes and sizes. The demand for polymer-based nanofibers grows due to its vast application in many fields like portable electronic devices, energy harvesting systems, water purifying devices, and gas separation. Every year more than three million people die from water-related diseases. Increasing the world’s population together with the declining water tables and increasing salinity of water resources, results in a crisis that is a primary concern, while the situation is getting worse every year. Among various water desalination technologies, Membrane Distillation (MD) is an emerging thermally-driven, membrane-based desalination technology highly suitable to treat hypersaline solutions. MD is a thermally driven process involving a nano/microporous, hydrophobic membrane through which only water vapor can diffuse. Compared to other membrane technologies, MD is a compact and low energy separation technology. Although MD has been investigated by researchers, it still cannot compete with other technologies such as reverse osmosis (RO), mainly due to lower production rate, energy efficiency, and fouling resistance. In the present study, modified PVDF electrospun nanofiber membrane composites with various support structures were studied for Direct Contact Membrane Desalination (DCMD) application. Hydrophobicity of the nanofiber membranes was investigated, and different parameter settings of the electrospinning process have been optimized in order to enhance the performance of the nanofiber membrane in the water desalination process. On the other hand, with the increasing demand for energy, it has become urgent to develop renewable energy technologies to sustain economic growth. Electrospun PVDF-TrFE nanofibers have excellent piezoelectric properties. The core concept of the piezoelectric effect is, when mechanical stress is applied, an electrical charge is generated from a piezoelectric material. The target of this research is to develop an energy harvesting approach that shows the techniques of fiber fabrication along with energy production from PVDF-TrFE nanofibers
Interfacial Fluidics using Liquid Metal Alloys
No full textIn this thesis, I highlight studies I have accomplished to investigate real-time physicochemical changes in gallium alloys immediately upon contact with microdroplets of various fluids. Such interactions are often overlooked due to the limited accessibility of specialized equipment. To tackle the challenge, I have introduced a nanoporous conductive wire platform fabricated by injecting eutectic gallium indium (eGaIn) into microtubes upcycled from artificial kidneys. This framework provides an economical and effective method to observe weak interfacial interactions within a nanoporous domain, enabling studies on fluid transport and interfacial dynamics. The platform also captures dynamic changes in gallium oxide’s amphoteric properties, which facilitate unique interactions with various fluids. It enables fluid transport and interaction within the nanoporous structure by providing direct access to reactive gallium oxide. The innovative design provides a foundation for future nano- and bioanalytical applications utilizing liquid metal alloys. In contrast to the nanoporous fiber studies, I have utilized 2D thin films of liquid metal to dissect true interactions with various fluids – especially microdroplets with dilute analytes. My research focus in this study was to demonstrate the chemo-mechanical stability of the film by harnessing atomic concentrations of gallium and oxygen. Three fluorinated samples were tested: 200 ppm PFOA, 0.014 ppb PFAS, and 0.001 ppb PFAS demonstrating sensitivity to varying PFAS concentrations. Energy-dispersive X-ray spectroscopy (EDS) and Raman spectroscopy were employed to quantify and validate the shifts in elemental distributions and surface dynamics of the eGaIn films. The results suggest that a 2D thin film of liquid metal can be harnessed for rapid in situ analysis of dilute analytes, offering a new pathway for chemical sensors. Additionally, I highlight how to use ImageJ to examine surface heterogeneity and defects, including pinholes, which are needed for the dynamic investigation of the 2D interface. Overall, interfacial fluidic studies will help understand the behavior of microdroplets of various fluids in real-time without relying on bulky and expensive analytical tools
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Confining Eutectic Gallium Indium (eGaIn) in Expired Artificial Kidneys to Unveil Nanoporous Conductive Wires
Get PDFNanoporous membranes have gained considerable interest in drug delivery1, ion
transportation2, micro/nanofluidics3, molecular sensing4, and separation
science5. Artificial kidneys, also known as dialyzers, reject pathogens and
other unwanted substances from the blood, utilize hundreds of soft and
nanoporous polymeric microtubes, and slowly become a burden to the environment
with the growing number of dialysis patients worldwide. We demonstrate the
fabrication of nanoporous conductive wires utilizing empty polysulfone
microtubes collected from expired and unused artificial kidneys, also known as
medical wastes. Injecting a fluidic, highly conductive, and room temperature
liquid alloy (eutectic gallium indium-eGaIn, 75% Ga, 25% In) into
microtubes of a twenty years old dialyzer, here, we have revealed a new class
of nanoporous and conductive functional materials. These conductive fibers
upcycle a medical waste, do not require expensive and conventional fabrication
processes, and still provide the quintessential metal-oxide/metal framework due
to the presence of the native surface oxide (i.e., Gallium Oxide, Ga2O3) of
eGaIn at the nanoconfinement (i.e., nanopores) for nano/biosensing. We
harnessed these new materials to sense and differentiate microliter volumes of
deionized (DI) water, 1M hydrochloric acid (HCl), and 95% ethanol (EtOH),
leveraging their electrical signatures. This new class of soft nanomaterials
has the potential to become the paradigm-shift platforms for the
next-generation of biomedical, bioelectronics, nanoelectronics, and sensor
devices
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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