Homogeneous Synthesis and Characterization of Sulfonated Polyarylethersulfones Having Low Degree of Sulfonation and Highly Hydrophilic Behavior

Valentina Sabatini,Stefano Checchia,Hermes Farina,Marco Aldo Ortenzi 한국고분자학회 2016 Macromolecular Research Vol.24 No.9

In the present paper, the wettability of polyarylethersulfones (PESs) was promoted through the controlled introduction of sulfonic groups in PES polymeric chain. Homogeneous synthesis using a sulfonated comonomer introduced sulfonic groups while exerting a tight control over the degree of sulfonation (DS) and avoiding the undesired side reactions brought about by heterogeneous sulfonation reactions. A series of sulfonated polyarylethersulfones (SPESs) with very low amounts of sulfonic groups - 0.5, 0.75, and 1 meq SO3 -*g-1 of polymer - was synthesized via polycondensation using 4,4'-difluorodiphenylsulfone, 4,4'-dihydroxydiphenyl and a sulfonated comonomer, 2,5- dihydroxybenzene-1-sulfonate potassium salt. The presence of sulfonic groups was confirmed by Fourier transform infrared (FTIR) spectra; the macromolecular structure and the real DS of SPESs were determined by 1H NMR; the molecular weights were investigated by size exclusion chromatography (SEC); ion exchange capacity (IEC) values, measured by potentiometric titration, are in good agreement with the experimental DS. The polyelectrolyte effect was studied on intrinsic viscosity (IV) measurements. The effect of DS on the thermal properties of SPES membranes was studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC); wetting properties were characterized by static water contact angle (SWCA) measurements on membranes obtained via solution casting. The results showed that an increased DS results in higher glass transition temperatures (Tg) and lower water contact angles, the latter dropping from 91o to 43o as DS was raised from 0 to 1.0 meq SO3 -*g-1. This work demonstrates that homogeneous synthesis of SPES is an efficient way to prepare SPES membranes with tightly controlled DS and enhanced hydrophilic properties, in particular, an excellent hydrophilic SWCA even at very low amounts of sulfonic moieties.

Exhaust emissions of a diesel engine using ethanol-in-palm oil/diesel microemulsion-based biofuels

Ampira Charoensaeng,Sutha Khaodhiar,David A. Sabatini,Noulkamol Arpornpong 대한환경공학회 2018 Environmental Engineering Research Vol.23 No.3

The use of palm oil and diesel blended with ethanol, known as a microemulsion biofuel, is gaining attention as an attractive renewable fuel for engines that may serve as a replacement for fossil-based fuels. The microemulsion biofuels can be formulated from the mixture of palm oil and diesel as the oil phase; ethanol as the polar phase; methyl oleate as the surfactant; alkanols as the cosurfactants. This study investigates the influence of the three cosurfactants on fuel consumption and exhaust gas emissions in a direct-injection (DI) diesel engine. The microemulsion biofuels along with neat diesel fuel, palm oil-diesel blends, and biodiesel-diesel blends were tested in a DI diesel engine at two engine loads without engine modification. The formulated microemulsion biofuels increased fuel consumption and gradually reduced the nitrogen oxides (NOx) emissions and exhaust gas temperature; however, there was no significant difference in their carbon monoxide (CO) emissions when compared to those of diesel. Varying the carbon chain length of the cosurfactant demonstrated that the octanol-microemulsion fuel emitted lower CO and NOx emissions than the butanol- and decanol-microemulsion fuels. Thus, the microemulsion biofuels demonstrated competitive advantages as potential fuels for diesel engines because they reduced exhaust emissions.

Tailoring the Energy Landscape in Quasi-2D Halide Perovskites Enables Efficient Green-Light Emission

Quan, Li Na,Zhao, Yongbiao,Garcí,a de Arquer, F. Pelayo,Sabatini, Randy,Walters, Grant,Voznyy, Oleksandr,Comin, Riccardo,Li, Yiying,Fan, James Z.,Tan, Hairen,Pan, Jun,Yuan, Mingjian,Bakr, Osman American Chemical Society 2017 NANO LETTERS Vol.17 No.6

<P>Organo-metal halide perovskites are a promising platform for optoelectronic applications in view of their excellent charge-transport and bandgap tunability. However, their low photoluminescence quantum efficiencies, especially in low-excitation regimes, limit their efficiency for light emission. Consequently, perovskite light-emitting devices are operated under high injection, a regime under which the materials have so far been unstable. Here we show that, by concentrating photoexcited states into a small subpopulation of radiative domains, one can achieve a high quantum yield, even at low excitation intensities. We tailor the composition of quasi-2D perovskites to direct the energy transfer into the lowest-bandgap minority phase and to do so faster than it is lost to nonradiative centers. The new material exhibits 60% photoluminescence quantum yield at excitation intensities as low as 1.8 mW/cm(2), yielding a ratio of quantum yield to excitation intensity of 0.3 cm(2)/mW; this represents a decrease of 2 orders of magnitude in the excitation power required to reach high efficiency compared with the best prior reports. Using this strategy, we report light-emitting diodes with external quantum efficiencies of 7.4% and a high luminescence of 8400 cd/m(2).</P>

Cytokinin‐facilitated proteolysis of ARABIDOPSIS RESPONSE REGULATOR 2 attenuates signaling output in two‐component circuitry

Kim, Kangmin,Ryu, Hojin,Cho, Young‐,Hyun,Scacchi, Emanuele,Sabatini, Sabrina,Hwang, Ildoo Blackwell Publishing Ltd 2012 The Plant journal Vol.69 No.6

<P><B>Summary</B></P><P>Cytokinins propagate signals via multiple phosphorelays in a mechanism similar to bacterial two‐component systems. In Arabidopsis, signal outputs are determined by the activation state of transcription factors termed type‐B Arabidopsis response regulators (ARRs); however, their regulatory mechanisms are largely unknown. In this study, we demonstrate that the proteolysis of ARR2, a type‐B ARR, modulates cytokinin signaling outputs. ARR2‐hemagglutinin (HA) is rapidly degraded by cytokinin treatment, but other type‐B ARRs, such as ARR1‐HA, ARR10‐HA, ARR12‐HA and ARR18‐HA, are not. ARR2 degradation is mediated by the <I>26S</I> proteasome pathway, and requires cytokinin‐induced phosphorylation of Asp80 residue in the receiver domain. Through mutational analysis of amino acid residues in the receiver domain, we found that substitution of Lys90 with Gly inhibits ARR2 degradation. <I>ARR2</I><SUP><I>K90G</I></SUP><I>‐HA</I> in transgenic Arabidopsis conferred enhanced cytokinin sensitivity in various developmental processes, including primary root elongation, callus induction, leaf senescence and hypocotyl growth. ARR2<SUP>K90G</SUP>‐HA increased the expression of type‐A <I>ARR</I>s, primary cytokinin‐responsive genes and indicators of signaling output in two‐component circuits. Expression of <I>ARR2</I><SUP><I>K90G</I></SUP><I>‐HA</I> from the native <I>ARR2</I> promoter in the <I>arr2‐4</I> knock‐out mutant also increased cytokinin sensitivity. In conclusion, ARR2 proteolysis is involved in the maintenance of the primary signaling output for normal developmental processes mediated by cytokinin in Arabidopsis.</P>

An Active System for Visually-Guided Reaching in 3D across Binocular Fixations

Martinez-Martin, Ester,del Pobil, Angel P.,Chessa, Manuela,Solari, Fabio,Sabatini, Silvio P. Hindawi Publishing Corporation 2014 The Scientific World Journal Vol.2014 No.-

<P>Based on the importance of relative disparity between objects for accurate hand-eye coordination, this paper presents a biological approach inspired by the cortical neural architecture. So, the motor information is coded in egocentric coordinates obtained from the allocentric representation of the space (in terms of disparity) generated from the egocentric representation of the visual information (image coordinates). In that way, the different aspects of the visuomotor coordination are integrated: an active vision system, composed of two vergent cameras; a module for the 2D binocular disparity estimation based on a local estimation of phase differences performed through a bank of Gabor filters; and a robotic actuator to perform the corresponding tasks (visually-guided reaching). The approach's performance is evaluated through experiments on both simulated and real data.</P>

Evaluation of Dyeing and UV Protective Properties on Hemp Fabric of Aqueous Extracts from Vegetal Matrices of Different Origin

Daniele Grifoni,Graziana Roscigno,Enrica De Falco,Annapia Vece,Francesca Camilli,Francesco Sabatini,Luca Fibbi,Gaetano Zipoli 한국섬유공학회 2020 Fibers and polymers Vol.21 No.8

Clothes are one of the most effective measures to minimize health hazards due to the current levels of UV radiationon the earth’s surface. Fabrics made of natural fibers and dyed with natural pigments are an excellent means to reduce UVexposure. In this study, the UV protection properties were tested on a vegetal fiber fabric (hemp) dyed with water extractsfrom madder, chestnut, onion, inula, and logwood, at three increasing concentrations. Dyeing extracts were obtained fromdifferent sources: agro-food industry residues (chestnut and onion), spontaneous (inula), and commercial dyeing plants(madder and logwood). The quantitative characterization of water dye extracts was performed to evaluate the amount of dyein pre- and post-dyeing solutions as well as the dye fastened to the fabric. The percentage values of dye fastened to the fabric,in relation to the plant dry weight, were relatively low for all the considered species. The fabric Ultraviolet Protection Factor(UPF) was evaluated using both a laboratory spectrophotometer and a spectroradiometer in outdoor conditions. Aprogressive increase in UPF with the increase of the dye-bath concentration was shown. Chestnut and onion, reaching theminimum protection level (UPF=15) at the highest dye-bath concentration, can be considered the most effective. The UPFpersistence of the fabrics was also evaluated after sun exposure and repeated washing. Colors and UV protective propertiesobtained by the dyeing procedure tested in this research can provide added value to hemp fabric and meet the demands of anexpanding “eco-friendly” market.

Perovskite energy funnels for efficient light-emitting diodes

Yuan, Mingjian,Quan, Li Na,Comin, Riccardo,Walters, Grant,Sabatini, Randy,Voznyy, Oleksandr,Hoogland, Sjoerd,Zhao, Yongbiao,Beauregard, Eric M.,Kanjanaboos, Pongsakorn,Lu, Zhenghong,Kim, Dong Ha,Sarge Nature Publishing Group 2016 Nature nanotechnology Vol.11 No.10

<P>Organometal halide perovskites exhibit large bulk crystal domain sizes, rare traps, excellent mobilities and carriers that are free at room temperature-properties that support their excellent performance in charge-separating devices. In devices that rely on the forward injection of electrons and holes, such as light-emitting diodes (LEDs), excellent mobilities contribute to the efficient capture of non-equilibrium charge carriers by rare non-radiative centres. Moreover, the lack of bound excitons weakens the competition of desired radiative (over undesired non-radiative) recombination. Here we report a perovskite mixed material comprising a series of differently quantum-size-tuned grains that funnels photoexcitations to the lowest-bandgap light-emitter in the mixture. The materials function as charge carrier concentrators, ensuring that radiative recombination successfully outcompetes trapping and hence non-radiative recombination. We use the new material to build devices that exhibit an external quantum efficiency (EQE) of 8.8% and a radiance of 80 W sr(-1) m(-2). These represent the brightest and most efficient solution-processed near-infrared LEDs to date.</P>

Integrating SARA Assessment with Reading Comprehension Training in AutoTutor

Smith E. Halle,Hollander John,Graesser Art C.,Sabatini John,Hu Xiangen 한국영어교육학회 2021 ENGLISH TEACHING(영어교육) Vol.76 No.-

Facing the demands of the pandemic and distance learning, English learners require educational technologies that are accessible, engaging, and effective. Meeting these demands requires educational technology developers to consider learners’ sociocultural contexts. Learning theories can be applied to meet individuals’ needs to optimize chances for participation, engagement, and learning gains. This article describes two Internet-based digital technologies that target struggling adult readers who need to improve their comprehension skills: SARA (Study Aid and Reading Assessment) and AutoTutor for Adult Reading Comprehension. The SARA assessment provides a diagnostic profile for individuals’ reading strengths and weaknesses. This profile can be used to guide the selection of reading comprehension lessons in AutoTutor-ARC, a digital technology that both adapts to learners’ performances and engages them in an immersive learning experience using a three-way conversation with computer agents acting as a tutor and a peer to discuss texts. We discuss how these technologies can be integrated into educational settings to improve engagement and learning.

Protective Measures From Solar Ultraviolet Radiation for Beach Lifeguards in Tuscany (Italy): Shade and Clothing Strategies

Grifoni Daniele,Betti Giulio,Bogi Andrea,Bramanti Lucia,Chiarugi Alessandra,Gozzini Bernardo,Morabito Marco,Picciolo Francesco,Sabatini Francesco,Miligi Lucia 한국산업안전보건공단 산업안전보건연구원 2022 Safety and health at work Vol.13 No.4

Background: The exposure to solar ultraviolet radiation is a significant risk factor generally underestimated by outdoor workers and employers. Several studies have pointed out that occupational solar exposure increased eye and skin diseases with a considerable impact on the lives and productivity of affected workers. The main purpose of this study was to evaluate the effectiveness against ultraviolet radiation of some measures recently undertaken for the protection of lifeguards in a coastal area of Tuscany. Methods: Different shading structures (gazebos and beach umbrella) were tested during a sunny summer’s day on a sandy beach by means of two radiometers; the UV protection offered by some T-shirts used by lifeguards was also tested in the laboratory with a spectrophotometer. Results: The analysed shading structures strongly reduced the ultraviolet radiation by up to 90%, however a not always negligible diffuse radiation is also present in the shade, requiring further protective measures (T-shirt, sunglasses, sunscreen, etc.); the tested T-shirts showed a very good-excellent protection according to the Australian/New Zealand standard. Conclusion: Results obtained in this study suggest how the adoption and dissemination of good practices, including those tested, could be particularly effective as a primary prevention for lifeguards who are subjected to very high levels of radiation for long periods.

A Hierarchical System for a Distributed Representation of the Peripersonal Space of a Humanoid Robot

Antonelli, Marco,Gibaldi, Agostino,Beuth, Frederik,Duran, Angel J.,Canessa, Andrea,Chessa, Manuela,Solari, Fabio,del Pobil, Angel P.,Hamker, Fred,Chinellato, Eris,Sabatini, Silvio P. IEEE 2014 IEEE transactions on autonomous mental development Vol.6 No.4

<P>Reaching a target object in an unknown and unstructured environment is easily performed by human beings. However, designing a humanoid robot that executes the same task requires the implementation of complex abilities, such as identifying the target in the visual field, estimating its spatial location, and precisely driving the motors of the arm to reach it. While research usually tackles the development of such abilities singularly, in this work we integrate a number of computational models into a unified framework, and demonstrate in a humanoid torso the feasibility of an integrated working representation of its peripersonal space. To achieve this goal, we propose a cognitive architecture that connects several models inspired by neural circuits of the visual, frontal and posterior parietal cortices of the brain. The outcome of the integration process is a system that allows the robot to create its internal model and its representation of the surrounding space by interacting with the environment directly, through a mutual adaptation of perception and action. The robot is eventually capable of executing a set of tasks, such as recognizing, gazing and reaching target objects, which can work separately or cooperate for supporting more structured and effective behaviors.</P>