1,721,055 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Fabrication of Electrospun Dual-Responsive Polymer Blend Nanofibers and its Application on Heavy Metal Removal from Aqueous Phase
No full textIndustrialization has indeed brought a revolutionary change and development on human lives, however it has also caused a lot of negative impacts on the environment; one of these is the contamination of the environment with heavy metals which, if not treated, can have a detrimental effect on the environment, biodiversity, and humans. Thus, there is a need for the removal of heavy metals, and adsorption is one of the widely used remediation techniques. In this study, multi-responsive PES-PDMAEMA nanofibers were fabricated via electrospinning and applied for the adsorption of Cu2+ from synthetic wastewater. The nanofibers were fabricated using a mixture of DMF/NMP solvents, and the effects of polymer concentration and PES/PDMAEMA blend ratio on the morphology of the nanofiber were determined. It was found that uniform and bead-free nanofibers were obtained at 35 w/v% polymer concentration at PES/PDMAEMA blend ratio greater than 50:50. Moreover, FTIR spectra and EDX elemental mapping showed that PES and PDMAEMA were successfully blended into the nanofibers. Adsorption of Cu2+ was done using different PES/PDMAEMA blend ratios and the combined effects of pH and temperature were studied. Nanofibers made of 70:30 PES/PDMAEMA was used in subsequent adsorption experiments and results show that the maximum adsorption capacity was observed at pH 6.5 and 55 ℃. Fitting the adsorption data to the pseudo-second order kinetic model, it was found that increasing the temperature, resulted to increase in the equilibrium adsorption capacity and rate of Cu2+ uptake by the PES/PDMAEMA nanofibers. This indicates that the Cu2+ removal by adsorption on the nanofibers is favored by a high temperature condition, which can be the result of an increased mobility of the metal ions with temperature and the polymer’s response to temperature. Using Langmuir and Freundlich isotherms, the values of RL and 1/n indicate that the adsorption of Cu2+ onto the nanofibers is favorable. The maximum adsorption capacity, qm, were calculated to be 50, 88.5, and 161.30 mg.g-1 for 25, 35, and 55 ℃, respectively. The effects of pH and temperature on the desorption of Cu2+ from the PES/PDMAEMA nanofibers was also studied. Results show that the maximum desorption value of 85% was observed at pH 3 and 25 ℃. Finally, reusability study was done for 5 adsorption cycles. In conclusion, PES/PDMAEMA has the capability to adsorb and desorb Cu2+ just by adjusting the pH and temperature, hence it can be considered as an efficient and economical adsorbent for heavy metals such Cu2+.Maste
Anti-biofouling effect of thin film nanocomposite membrane with functionalized carbon nanotube blended polymeric support layer
No full textIn this research, we focus on the analysis of anti-biofouling effect of thin film nanocomposite (TFC) membrane with functionalized carbon nanotube blended polymeric support layer to determine the potential of application in forward osmosis (FO) and pressure retarded osmosis (PRO) process. We fabricated thin film nanocomposite membranes with functionalized carbon nanotube to mitigate microorganism attachment and growth on surface of membrane. Fabricated membranes are characterized by SEM, FTIR, Contact angle, AFM, Zeta potential analysis. Anti-biofouling effect of fabricated membrane is analyzed by attachment test, biofouling test in cross flow. In previous researches, carbon nanotube has been used to reduce biofouling by incorporating in active layer. However, in this study, we analyzed anti-biofouling effect of carbon nanotube incorporating in support layer of TFC membrane.
The fabricated nanocomposite membrane with 0.5wt% fCNT has enhanced anti-biofouling property compared to bare TFC membrane in PRO mode - low roughness, high negative surface charge, hydrophilicity. Bacteria attachment on membrane decline approximately 35% compared to bare TFC membrane in PRO mode. In lab scale biofouling test, fCNT0.5-TFC membrane shows less flux decrease compared to bare TFC membrane. This biofouling reduction is due to the less accumulation of bacteria on membrane surface due to anti-biofouling property of membrane.
Therefore, this research shows fCNT composite TFC membranes have high potential in overcoming the current biofouling problem in PRO process with increased water flux. Even so, complexity of anti-biofouling mechanism makes it hard to clarify main factor of anti-biofouling effect, it requires further study to understand main mechanism for anti-biofouling effect on fCNT composite TFC membrane. Also, weather antimicrobial property of fCNT inhibits bacteria growth or not.Maste
Variations on the Author
Full text link“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
Full text linkWe 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
Fabrication of carbon nanotube buckypaper/polymer nanofiber composite hybrid film for high-performance electromagnetic interference (EMI) shielding
No full textIn the high-tech industry, the electromagnetic interference (EMI) issues can be called the electromagnetic environment in terms of global environment. By increasing electronic devices, following electromagnetic waves increasing caused by cell phone, military equipment and the other various ubiquitous things. So, EMI shielding that is the underlying solution has been getting more attention recently. Although EMI shielding materials is being actively researched, there has a limitation on strong mechanical strength, lightweight for practicality, high efficiency, and flexibility for successful edge control in electronic devices.
In this paper, a coaxial electrospun nanofiber (PI/PVP) based hybrid EMI shielding nanofiber film was fabricated with carbon nanotube(CNT) Buckypaper via vacuum filtration method. In terms of a coaxial electrospun nanofiber (PI/PVP), PI is used as a material having the various advantages of the polymer itself as a core part, and PVP is used as a sacrificial material as a shell part.
These are new method of fabrication of hybrid EMI shielding film using coaxial electrospun polymer nanofiber and carbon nanotube based Buckypaper. In addition, various parameters have been changed into excellent EMI shielding in terms of carbon nanotube based Buckypaper. Moreover, hybrid EMI shielding film (<40um) shows in ~48dB shielding efficiency (EMI SE) with mechanical strength ~15MPa. Considering the prepared hybrid coaxial electrospun nanofiber film that used as electromagnetic interference shielding film, this film can be satisfactorily applied for portable electronics, mobile, military equipment and suitable film for global electromagnetic environment in line with the high-tech industries.Maste
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
Efficacy of ionic/non-ionic surfactants and electret nanomaterials on PES electrospun nanofiber filters for PM0.3 filtration
No full textAir pollution is now considered the biggest threat to human health as it brings millions of deaths annually. One of the primary air pollutants, particulate matter (PM), can induce eye, skin, and nose irritation, and travel deep into the respiratory tract, affecting lung functions and causing lung cancer and heart diseases. This issue brings up the urgent need for highly effective air filtration membranes. Even though there are several commercially produced melt-blown air filters, their potential is limited by a large fiber diameter, filtration efficiency loss, and non- reusability. Still, producing air filters that achieve high efficiency and low air resistance is challenging. Thus, this work focuses on the introduction of different types of surfactants and nanomaterials to the commonly used polymer, such as polyethersulfone (PES), to produce nanofiber membranes for the PM0.3 filtration of by one-step electrospinning process for the investigation of the efficacy of surfactants and nanomaterials on membrane’s morphology, fiber diameter, pore size, filtration efficiency, etc. Surfactants effectively improved filtration efficiency up to 95% against PM0.3 particles by reducing fiber diameter and pore size, which improved interception effect, compared to 86.7% of pure PES membrane. Nanomaterials such as Barium Titanate and Silicon Nitride were used as charge enhancers, and they contributed to the improvement of the filtration performance, reaching 96.9% of filtration efficiency and 33.3 Pa of pressure drop, thanks to both modified morphology and improved electrostatic force. Shortly, the main goal of this work is to study the filtration performance of the electrospun PES nanofiber membranes under the effect of different surfactant types and electret nanoparticles.Maste
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