Derivatives of scattering profiles: tools for nanoparticle characterization

This paper presents a new approach to characterize nanoparticles using derivatives of scattering profiles of evanescent waves/surface plasmons. We start the procedure using the scattering profiles for an unknown configuration of nanoparticles, either from physical experiments or numerical simulations conducted for different nanoparticles on surfaces. We apply the statistical technique of compound estimation to recover the derivatives of scattering profiles. The L(1) discrepancies with the corresponding curves from known configurations are used to identify the most plausible configuration of particles that could yield the "experimental" profiles. We conduct a simulation study to see how often the new procedure correctly recovers the agglomeration level for gold spherical nanoparticles on a thin gold film. The results suggest that first derivatives are much more effective for characterization than undifferentiated profiles and that M(33) is the most useful element for distinguishing among configurations. The proposed compound estimation technique is more effective than typical inverse analyses based on look-up tables and can be used effectively in nanoparticle characterization platforms.     

Towards a Knowledge-Level Model of Context and Context Use in Diagnostic Problems

Diagnostic support systems that help solving problems in open and weak theory domains need to be context-sensitive in order to reveal flexible and efficient behaviour. This paper presents a task-oriented methodology for analysing and modeling contextual knowledge at the knowledge level. We present a context-sensitive diagnosis approach (ConSID) which clarifies the connection between content and process knowledge. The former embodies the domain model, while the latter embodies the task and method models. We present a prototypical system, the ConSID-Creek, that applies the ConSID approach to the medical diagnostic domain. We illustrate how the system integrates case-based and explanation-based reasoning paradigms when realizing the abductive subtask of the overall diagnostic task.     

Enhancement of uranyl ion uptake by prestructuring of acrylamide–maleic acid hydrogels

Acrylamide–maleic acid (AAm–MA) hydrogels were prepared by gamma‐irradiation of their aqueous solutions. UO₂⁺² ion uptake on P(AAm–MA) hydrogels was investigated using two types of gel systems prepared by a simple irradiation method and a prestructured reaction. It has been observed that gels prestructured with UO₂⁺² ions adsorbed approximately 15–20% more UO₂⁺² ions than gels prepared in pure water (the usual method). It was also found that the uranyl ion adsorption capacity of hydrogels increased with an increasing amount of maleic acid in the gel system and an increasing concentration of uranyl ion in the solution. A possible interaction mechanism between the groups in the copolymeric gels and UO₂⁺² ion has been proposed based on the stoichiometry and the spectroscopic evidence. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 284–289, 2000     

Multichromic polymers based on pyrene clicked thienylpyrrole

In this study, the effect of pendant pyrene on the optical and electronic properties of poly(2,5‐dithienylpyrrole)s was studied. For this purpose a new pyrene coupled 2,5‐dithienylpyrrole derivative (SNS‐pyrene) was synthesized through click reaction. SNS‐pyrene was electrochemically polymerized and its electrochemical and optical properties were investigated by electrochemical and optical techniques. The polymer had a band gap of 3.36 eV and displayed light green to blue color variation upon oxidation in less than 2.48 s. Additionally, electrochemical copolymerization of SNS‐pyrene with 3,4‐ethylenedioxythiophene was achieved whilst a detailed investigation was performed on the effect of electrochemical polymerization conditions on the optoelectronic properties of the copolymers. Studies revealed that the copolymers exhibit multichromic reversible redox behavior with lower band gaps and shorter switching times than their parent polymer, P(SNS‐pyrene) © 2014 Society of Chemical Industry.     

Environmentally friendly synthesis and photopolymerization of acrylated methyl ricinoleate for biomedical applications

In this study, we aimed to develop an efficient synthesis and photopolymerization of acrylated methyl ricinoleate (AMR) for biomedical applications. During the first step of the synthesis, methyl ricinoleate (MR) and boric acid were esterified via azeotropic distillation in toluene. Afterward, MR–boric acid ester was acrylated with acrylic acid at 165 °C via a boric acid ester acidolysis reaction. The bulk photopolymerization of AMR was performed in the presence of the photoinitiator 2,2-dimethoxy-2-phenyl acetophenone (DMPA) under 365 nm UV irradiation. Even with the use of 0.4% DMPA, a 35% monomer conversion was achieved within 30 min. Moreover, AMR, the plant-oil-based monomer, was also copolymerized with N-isopropyl acrylamide to obtain thermoresponsive hydrogels on the glass surface for biomedical applications. The synthesized materials were characterized by Fourier transform infrared (FTIR) spectroscopy, ¹H-NMR spectroscopy, and thermal characterization via thermogravimetric analysis (TGA) and differential scanning calorimetry techniques. The surfaces were characterized by FTIR and Energy Dispersive X-ray (EDS) spectroscopy. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47969.     

Enhancement of the fuel cell performance of a high temperature proton exchange membrane fuel cell running with titanium composite polybenzimidazole-based membranes

The fuel cell performance of a composite PBI-based membrane with TiO₂ has been studied. The behaviour of the membrane has been evaluated by comparison with the fuel cell performance of other PBI-based membranes, all of which were cast from the same polymer with the same molecular weight. The PBI composite membrane incorporating TiO₂ showed the best performance and reached 1000 mW cm⁻² at 175 °C. Moreover, this new titanium composite PBI-based membrane also showed the best stability during the preliminary long-term test under our operation conditions. Thus, the slope of the increase in the ohmic resistance of the composite membrane was 0.041 mΩ cm² h⁻¹ and this is five times lower than that of the standard PBI membrane. The increased stability was due to the high phosphoric acid retention capacity - as confirmed during leaching tests, in which the Ti-based composite PBI membrane retained 5 mol of H₃PO₄/PBI r.u. whereas the PBI standard membrane only retained 1 mol H₃PO₄/PBI r.u. Taking into account the results obtained in this study, the TiO₂-PBI based membranes are good candidates as electrolytes for high temperature PEMFCs.     

Effect of minimal neutralization at optimal conditions on minor components and oxidation stability of sunflower oil

In this study, oxidatively stable minimal neutralized sunflower seed oils were produced using three chemicals (Ca(OH)₂, MgO, and Na₂SiO₃) under previously determined optimal process conditions. Lipid oxidation rates at these optimum conditions were compared to the oils neutralized with NaOH (0.20%, 40°C, 15 min). It was concluded that the oils neutralized by NaOH had the shortest hydroperoxide and hexanal lag phases, thus were the least stable oils. Oils neutralized by Ca(OH)₂, MgO, and Na₂SiO₃ had lower FFA and higher oxidative stability than oil neutralized by NaOH. The study focused on which weak alkaline has higher oxidation stability and minimum FFA content and maximum acceptable tocopherol content. The oil neutralized by Ca(OH)₂ had the lowest FFA value and highest total phenolics and α-tocopherol contents and it had better oxidative stability than oil neutralized by NaOH. It suggests that Ca(OH)₂ could be more effective in producing a high quality oil.     

Split-attention effects in multimedia learning environments: eye-tracking and EEG analysis

Multimedia Tools and Applications - This study aimed to evaluate the split-attention effect in multimedia learning environments via objective measurements as EEG and eye-tracking. Two different...