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51.
Kouroupetroglou Georgios Pino Alexandros Riga Paraskevi 《Multimedia Tools and Applications》2017,76(4):5347-5366
Multimedia Tools and Applications - Mobile technologies provide radical opportunities in the domain of Assistive Technologies (AT) for persons with disabilities and the elderly by facilitating them... 相似文献
52.
Synthesis and characterization of electrically conducting copolymers based on biphenyl and thiophene
New electrically conducting copolymers based on biphenyl and thiophene in a form of film were synthesized by electropolymerization using potentiostatic conditions and the corresponding homopolymers, polyphenylenes, and polythiophenes, for comparison reasons. Different values of applied potential were used, to study its effect on the structure, morphology, and electrical conductivity of the films. From the analysis of the current‐time curves, it was found that the growth of the films follows layer by layer (2D) mechanism. The films were studied by FTIR, TGA, XRD, SEM‐EDAX and their electrical conductivity was determined, as well as their energy gap (Eg) by cyclic voltammetry. The copolymers had higher conductivity (appr. 1 S/cm) and lower Eg (appr. 1.2 eV) than that of the corresponding homopolymers. These materials due to their high conductivity, high stability under repetitive potential cycling, and partial solubility are candidates for electronic applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
53.
P. Tong Despina Louca X.-J. Gu S. J. Poon G. J. Shiflet T. Proffen 《Metallurgical and Materials Transactions A》2011,42(6):1481-1485
Fluctuations in the microstructure with chemical alloying of Fe multicomponent bulk metallic glasses were characterized via the pair density function analysis of neutron diffraction data. In the two systems investigated, (Fe/Mo)76P12C10B2 and Fe49Cr15Mo14Er1(C/B)21, it is shown that the atomic topology is sensitive to even small chemical fluctuations. In phosphorous containing glasses, (Fe/Mo)76P12C10B2, increasing the atomic percent of Mo brings about changes of the microstructure, particularly in the short-range environment involving Mo-C/B and Fe-P pair correlations. In Fe49Cr15Mo14Er1(C/B)21, the systematic increase of B results in a shift of the center of mass of the first coordination shell and an increase in the coordination of the second shell, reflecting a local rearrangement brought upon the substitution of B for C. 相似文献
54.
Helen V. Botitsi Spiros D. Garbis Anastasios Economou Despina F. Tsipi 《Mass spectrometry reviews》2011,30(5):907-939
Analysis of pesticides and their metabolites in food and water matrices continues to be an active research area closely related to food safety and environmental issues. This review discusses the most widely applied mass spectrometric (MS) approaches to pesticide residues analysis over the last few years. The main techniques for sample preparation remain solvent extraction and solid‐phase extraction. The QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) approach is being increasingly used for the development of multi‐class pesticide residues methods in various sample matrices. MS detectors—triple quadrupole (QqQ), ion‐trap (IT), quadrupole linear ion trap (QqLIT), time‐of‐flight (TOF), and quadrupole time‐of‐flight (QqTOF)—have been established as powerful analytical tools sharing a primary role in the detection/quantification and/or identification/confirmation of pesticides and their metabolites. Recent developments in analytical instrumentation have enabled coupling of ultra‐performance liquid chromatography (UPLC) and fast gas chromatography (GC) with MS detectors, and faster analysis for a greater number of pesticides. The newly developed “ambient‐ionization” MS techniques (e.g., desorption electrospray ionization, DESI, and direct analysis in real time, DART) hyphenated with high‐resolution MS platforms without liquid chromatography separation, and sometimes with minimum pre‐treatment, have shown potential for pesticide residue screening. The recently introduced Orbitrap mass spectrometers can provide high resolving power and mass accuracy, to tackle complex analytical problems involved in pesticide residue analysis. © 2010 Wiley Periodicals, Inc., Mass Spec Rev 30:907–939, 2011 相似文献
55.
Christina Anniva Despina Grigoriadou Eleni Psomiadou Maria Z. Tsimidou 《Journal of the American Oil Chemists' Society》2006,83(4):371-375
In previous studies we reported the presence of compounds with spectral characteristics similar to pheophytin α (Pheo α),
which often accompany the Pheo α peak in the chromatographic profile of virgin olive oils (VOO) at 410 nm under normal-phase
HPLC conditions. The occurrence and levels of these compounds were found to be affected by storage conditions of the oil samples.
In the present study we investigated whether the major Pheo a degradation products, identified as pyropheophytin α (coeluting
with the respective epimer) and 132-OH-pheophytin α, could be used as estimates of VOO history. The content of Pheo α and its degradation products was determined
for a great number of authentic olive oil samples of unknown history. Results are discussed in comparison with other quality
indices (e.g., antioxidant content) when necessary. High amounts of the pyro form (20–30% of total pheophytins) were related
to thermal abuse or lengthy storage. The presence of allomers indicated oxygen availability. The levels of these products,
0–20% of the total pheophytin content for 62% of the samples, seemed to be influenced by the presence of pro- and antioxidants.
When low levels of Pheo α are not accompanied by other degradation products, light exposure for a certain period of storage
can be assumed. 相似文献
56.
Poly(p‐phenylene) (H‐PPP), which is one of the firstly investigated conducting polymer, has the disadvantage of difficult processability because it is infusible and insoluble. The use of biphenyl instead of benzene leads to ortho‐, meta‐, para‐polyphenylenes (H‐PP) which are more soluble and easier to be processed, however their electrical conductivity is lower. Copolymers of polyphenylenes (C1 and C2) and corresponding homopolymers (H‐PPP and H‐PP) were produced by the oxidative cationic polymerization of benzene and/or biphenyl. The soluble (‐S) and the insoluble (‐I) in chlorobenzene polyphenylenes were separated (H‐PP‐I, H‐PP‐S, C1‐I, C1‐S, C2‐I, and C2‐S) and they were doped with a solution of FeCl3. All polyphenylenes were studied by FTIR, XRD, TGA, and their electrical conductivity with constant current was determined. Pronounced differences between the copolymers and the homopolymers were observed, indicating the different structure of the former. The values of the electrical conductivity of doped insoluble copolymers (10?4 and 10?5 S/cm) are between that of H‐PPP (10?3 S/cm) and H‐PP‐I (10?6 S/cm). The values of the electrical conductivity of doped soluble copolymers (10?5 S/cm) are considerably higher than that of H‐PP‐S (10?9 S/cm). The new electrically conductive polyphenylenes that were produced differ significantly from the corresponding homopolymers and combine good electrical conductivity and solubility. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
57.
Carbon nanotubes production over Co/silica catalysts 总被引:1,自引:0,他引:1
K. Hernadi A. Fonseca P. Piedigrosso M. Delvaux J.B. Nagy D. Bernaerts J. Riga 《Catalysis Letters》1997,48(3-4):229-238
58.
Copolymer films of biphenyl and pyrrole were synthesized by electrochemical polymerization. The influence of the applied potential used for the electropolymerization on the structure, morphology, electrical conductivity, and stability of the films was examined. From the analysis of the current–time curves, it was found that the growth of the copolymer films starts immediately. The films were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis, X-ray diffraction analysis, and scanning electron microscopy–energy-dispersive X-ray analysis, and their electrical conductivity (σ), energy gap (Eg), and electrochemical stability were also determined. Based on the results, the copolymers were classified into three groups. The first includes the (PP-PPy)0.80 copolymer synthesized at the lowest potential Eox (0.80 V), having the highest ratio R (R = 0.35) of quinoid to benzenoid rings (calculated from FTIR), the highest value of σ (σ = 0.9 S/cm), the lowest Eg (Eg = 1.20 eV), and has compact morphology. The second group concerns the copolymers synthesized at higher potential (0.82 up to 0.86 V), having lower R (∼ 0.20), lower σ (below 0.4 S/cm), higher Eg (∼ 1.35 eV), and they are less compact with many pores. The third group includes the copolymers synthesized at even higher applied potential (0.88 and 0.90 V), having even lower R values (∼ 0.10), significantly lower σ (∼ 10−3 S/cm), even higher Eg (∼ 1.70 eV), and they are very porous. The applied potential during electropolymerization strongly affects the properties of the synthesized copolymers. Because of the combination of high conductivity, low energy gap, and partial solubility with significant electrochemical stability, these new copolymers are attractive candidates for many applications. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
59.
Bayer IS Fragouli D Attanasio A Sorce B Bertoni G Brescia R Di Corato R Pellegrino T Kalyva M Sabella S Pompa PP Cingolani R Athanassiou A 《ACS applied materials & interfaces》2011,3(10):4024-4031
We demonstrate a simple but highly efficient technique to introduce multifunctional properties to cellulose fiber networks by wetting them with ethyl-cyanoacrylate monomer solutions containing various suspended organic submicrometer particles or inorganic nanoparticles. Solutions can be applied on cellulosic surfaces by simple solution casting techniques or by dip coating, both being suitable for large area applications. Immediately after solvent evaporation, ethyl-cyanoacrylate starts cross-linking around cellulose fibers under ambient conditions because of naturally occurring surface hydroxyl groups and adsorbed moisture, encapsulating them with a hydrophobic polymer shell. Furthermore, by dispersing various functional particles in the monomer solutions, hydrophobic ethyl-cyanoacrylate nanocomposites with desired functionalities can be formed around the cellulose fibers. To exhibit the versatility of the method, cellulose sheets were functionalized with different ethyl-cyanoacrylate nanocomposite shells comprising submicrometer wax or polytetrafluoroethylene particles for superhydophobicity, MnFe(2)O(4) nanoparticles for magnetic activity, CdSe/ZnS quantum dots for light emission, and silver nanoparticles for antimicrobial activity. Morphological and functional properties of each system have been studied by scanning and transmission electron microscopy, detailed contact angle measurements, light emission spectra and E. coli bacterial growth measurements. A plethora of potential applications can be envisioned for this technique, such as food and industrial packaging, document protection, catalytic cellulosic membranes, textronic (electrofunctional textiles), electromagnetic devices, authentication of valuable documents, and antimicrobial wound healing products to name a few. 相似文献
60.
Despina Stavrinos Jennifer L. Jones Annie A. Garner Russell Griffin Crystal A. Franklin David Ball Sharon C. Welburn Karlene K. Ball Virginia P. Sisiopiku Philip R. Fine 《Accident; analysis and prevention》2013
Studies have documented a link between distracted driving and diminished safety; however, an association between distracted driving and traffic congestion has not been investigated in depth. The present study examined the behavior of teens and young adults operating a driving simulator while engaged in various distractions (i.e., cell phone, texting, and undistracted) and driving conditions (i.e., free flow, stable flow, and oversaturation). Seventy five participants 16–25 years of age (split into 2 groups: novice drivers and young adults) drove a STISIM simulator three times, each time with one of three randomly presented distractions. Each drive was designed to represent daytime scenery on a 4 lane divided roadway and included three equal roadway portions representing Levels of Service (LOS) A, C, and E as defined in the 2000 Highway Capacity Manual. Participants also completed questionnaires documenting demographics and driving history. Both safety and traffic flow related driving outcomes were considered. A Repeated Measures Multivariate Analysis of Variance was employed to analyze continuous outcome variables and a Generalized Estimate Equation (GEE) Poisson model was used to analyze count variables. Results revealed that, in general more lane deviations and crashes occurred during texting. Distraction (in most cases, text messaging) had a significantly negative impact on traffic flow, such that participants exhibited greater fluctuation in speed, changed lanes significantly fewer times, and took longer to complete the scenario. In turn, more simulated vehicles passed the participant drivers while they were texting or talking on a cell phone than while undistracted. The results indicate that distracted driving, particularly texting, may lead to reduced safety and traffic flow, thus having a negative impact on traffic operations. No significant differences were detected between age groups, suggesting that all drivers, regardless of age, may drive in a manner that impacts safety and traffic flow negatively when distracted. 相似文献