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Appl. Sci., Volume 2, Issue 2 (June 2012) – 22 articles , Pages 245-565

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203 KiB  
Editorial
Special Feature Organo-Fluorine Chemical Science
by Helmut Martin Hügel and Neale Jackson
Appl. Sci. 2012, 2(2), 558-565; https://doi.org/10.3390/app2020558 - 4 Jun 2012
Cited by 20 | Viewed by 8570
Abstract
Fluorine is the 13th most abundant element and, with other fluorine containing functional groups, is a most effective element in biological substances, pharmaceuticals, agrochemicals, liquid crystals, dyes, polymers and a wide range of consumer products. This reflects its resistance to metabolic change due [...] Read more.
Fluorine is the 13th most abundant element and, with other fluorine containing functional groups, is a most effective element in biological substances, pharmaceuticals, agrochemicals, liquid crystals, dyes, polymers and a wide range of consumer products. This reflects its resistance to metabolic change due to the strength of the C-F bond providing biological stability and the application of its nonstick-interfacial physical characteristics. Its introduction often remains a synthetic challenge. The widespread use of organofluorines has increased the demand for the development of practical and simple reagents and experimental strategies for the incorporation of fluorine into all types of molecular structures and this was the reasoning behind this special feature on Organo-Fluorine Chemical Science.The contributed articles belong to two broad groups: (i) preparation of fluorine materials, polymers; (ii) the synthesis/applications of organo-fluorine molecules. [...] Full article
(This article belongs to the Special Issue Organo-Fluorine Chemical Science)
309 KiB  
Article
Effects of Nonlinear Chirp on the Self-Phase Modulation of Ultrashort Optical Pulses
by Akira Suda and Takanori Takeda
Appl. Sci. 2012, 2(2), 549-557; https://doi.org/10.3390/app2020549 - 4 Jun 2012
Cited by 22 | Viewed by 7550
Abstract
In this article, we analytically investigate the spectral broadening by self-phase modulation of strongly chirped optical pulses. The dispersion due to the nonlinear optical process is expressed as functions of a linear and a nonlinear initial chirp. As a result, it is found [...] Read more.
In this article, we analytically investigate the spectral broadening by self-phase modulation of strongly chirped optical pulses. The dispersion due to the nonlinear optical process is expressed as functions of a linear and a nonlinear initial chirp. As a result, it is found that the third-order dispersion strongly depends on the initial linear chirp and the nonlinearity for self-phase modulation. Full article
(This article belongs to the Special Issue Feature Papers)
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561 KiB  
Article
High Performance Shape Memory Polyurethane Synthesized with High Molecular Weight Polyol as the Soft Segment
by Manzoor Ahmad, Bin Xu, Hendra Purnawali, Yongqing Fu, Weimin Huang, Mohsen Miraftab and Jikui Luo
Appl. Sci. 2012, 2(2), 535-548; https://doi.org/10.3390/app2020535 - 31 May 2012
Cited by 56 | Viewed by 10603
Abstract
Shape memory polyurethanes (SMPUs) are typically synthesized using polyols of low molecular weight (MW~2,000 g/mol) as it is believed that the high density of cross-links in these low molecular weight polyols are essential for high mechanical strength and good shape memory [...] Read more.
Shape memory polyurethanes (SMPUs) are typically synthesized using polyols of low molecular weight (MW~2,000 g/mol) as it is believed that the high density of cross-links in these low molecular weight polyols are essential for high mechanical strength and good shape memory effect. In this study, polyethylene glycol (PEG-6000) with MW ~6000 g/mol as the soft segment and diisocyanate as the hard segment were used to synthesize SMPUs, and the results were compared with the SMPUs with polycaprolactone PCL-2000. The study revealed that although the PEG-6000-based SMPUs have lower maximum elongations at break (425%) and recovery stresses than those of PCL-based SMPUs, they have much better recovery ratios (up to 98%) and shape fixity (up to 95%), hence better shape memory effect. Furthermore, PEG-based SMPUs showed a much shorter actuation time of < 10 s for up to 90% shape recovery compared to typical actuation times of tens of seconds to a few minutes for common SMPUs, demonstrated their great potential for applications in microsystems and other engineering components. Full article
(This article belongs to the Special Issue Feature Papers)
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1278 KiB  
Review
Magnetic Nanoparticles in the Imaging of Tumor Angiogenesis
by Shaunagh McDermott and Alexander R. Guimaraes
Appl. Sci. 2012, 2(2), 525-534; https://doi.org/10.3390/app2020525 - 29 May 2012
Cited by 8 | Viewed by 7179
Abstract
Angiogenesis, the growth of new capillary blood vessels, is central to the growth of tumors. Non-invasive imaging of tumor angiogenesis will allow for earlier detection of tumors and also the development of surrogate markers for assessing response to treatment. Steady state magnetic resonance [...] Read more.
Angiogenesis, the growth of new capillary blood vessels, is central to the growth of tumors. Non-invasive imaging of tumor angiogenesis will allow for earlier detection of tumors and also the development of surrogate markers for assessing response to treatment. Steady state magnetic resonance imaging with magnetic nanoparticles is one method to assess angiogenesis. In this article we explain the theory behind steady state magnetic resonance imaging and review the available literature. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles: Synthesis, Properties and Applications)
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858 KiB  
Article
Magnetic Amphiphilic Composites Applied for the Treatment of Biodiesel Wastewaters
by Bruno R. S. Lemos, Ana Paula C. Teixeira, José D. Ardisson, Waldemar A. A. Macedo, Luis E. Fernandez-Outon, Camila C. Amorim, Flávia C. C. Moura and Rochel M. Lago
Appl. Sci. 2012, 2(2), 513-524; https://doi.org/10.3390/app2020513 - 29 May 2012
Cited by 29 | Viewed by 7638
Abstract
In this work, new magnetic amphiphilic composites were prepared by chemical vapor deposition with ethanol on the surface of hydrophilic natural chrysotile matrix containing Fe catalyst. XRD, Raman, Mössbauer and SEM analyses suggest the formation of a complex nanostructured material composed of hydrophobic [...] Read more.
In this work, new magnetic amphiphilic composites were prepared by chemical vapor deposition with ethanol on the surface of hydrophilic natural chrysotile matrix containing Fe catalyst. XRD, Raman, Mössbauer and SEM analyses suggest the formation of a complex nanostructured material composed of hydrophobic carbon nanotubes/nanofibers grown on the hydrophilic surface of the MgSi fiber mineral and the presence of Fe metallic nanoparticles coated by carbon. These nanostructured particles show amphiphilic properties and interact very well with both oil and aqueous phases. When added to emulsions the amphiphilic particles locate on the oil/water interface and, under a magnetic field, the oil droplets collapsed leading to the separation of the aqueous and oil phases. Preliminary work showed excellent results on the use of these particles to break wastewater emulsions in the biodiesel process. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles: Synthesis, Properties and Applications)
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217 KiB  
Review
Overview of the Development of the Fluoropolymer Industry
by Hongxiang Teng
Appl. Sci. 2012, 2(2), 496-512; https://doi.org/10.3390/app2020496 - 29 May 2012
Cited by 221 | Viewed by 25104
Abstract
The present review briefly describes the development of the fluoropolymer industry in the past 70 years. Discussed are industrial fluoropolymers including polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidenefluoride, polyvinylfluoride, ETFE, ECTFE, FEP, PFA, THV, Teflon AF and Cytop. Nafion is included as a special functional fluoropolymer material. [...] Read more.
The present review briefly describes the development of the fluoropolymer industry in the past 70 years. Discussed are industrial fluoropolymers including polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidenefluoride, polyvinylfluoride, ETFE, ECTFE, FEP, PFA, THV, Teflon AF and Cytop. Nafion is included as a special functional fluoropolymer material. These industrial fluoropolymers are introduced in the order of their discovery or time of first production, included are their chemical structures, thermal properties, mechanical properties, electrical and electronic properties, optical properties, chemical resistance, oxidative stabilities, weather stabilities, processabilities and their general applications. The main manufacturing companies for the different types of fluoropolymer products are also mentioned. Full article
(This article belongs to the Special Issue Organo-Fluorine Chemical Science)
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742 KiB  
Communication
Polydimethylsiloxane (PDMS) Coating onto Magnetic Nanoparticles Induced by Attractive Electrostatic Interaction
by Carina Sötebier, Aude Michel and Jérôme Fresnais
Appl. Sci. 2012, 2(2), 485-495; https://doi.org/10.3390/app2020485 - 29 May 2012
Cited by 21 | Viewed by 13430
Abstract
In this article, we present an efficient synthesis pathway of polydimethylsiloxane (PDMS) coated magnetic nanoparticles from hydrophilic polyacrylate coated ferrofluids (NPPAA). A block copolymer based on polydimethylsiloxane is selected for its propensity to interact with the carboxylate functions on the NPPAA. The interaction [...] Read more.
In this article, we present an efficient synthesis pathway of polydimethylsiloxane (PDMS) coated magnetic nanoparticles from hydrophilic polyacrylate coated ferrofluids (NPPAA). A block copolymer based on polydimethylsiloxane is selected for its propensity to interact with the carboxylate functions on the NPPAA. The interaction is due to negative charges on NPPAA and positive ones on the amphiphilic copolymer. The synthesis is achieved by interfacial interaction, simplifying the purification of the PDMS-coated nanoparticles (NPPDMS) from subproducts such as ions and water. NPPDMS are well dispersed in hydrophobic solvents (toluene, diethyl ether) and can then be embedded into a curable PDMS polymer. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles: Synthesis, Properties and Applications)
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259 KiB  
Article
Closed Form Representations of Some Series in Darling’s Model for Squeeze Film Damping with a Rectangular Plate
by Martin Gugat
Appl. Sci. 2012, 2(2), 479-484; https://doi.org/10.3390/app2020479 - 21 May 2012
Cited by 1 | Viewed by 6240
Abstract
Compressible squeeze film damping is a phenomenon of great importance for micromachines. For example, for the optimal design of an electrostatically actuated micro-cantilever mass sensor that operates in air, it is essential to have a model for the system behavior that can be [...] Read more.
Compressible squeeze film damping is a phenomenon of great importance for micromachines. For example, for the optimal design of an electrostatically actuated micro-cantilever mass sensor that operates in air, it is essential to have a model for the system behavior that can be evaluated efficiently. An analytical model that is based upon a solution of the linearized Reynolds equation has been given by R.B. Darling. In this paper we explain how some infinite sums that appear in Darling’s model can be evaluated analytically. As an example of applications of these closed form representations, we compute an approximation for the critical frequency where the spring component of the reaction force on the microplate, due to the motion through the air, is equal to a certain given multiple of the damping component. We also show how some double series that appear in the model can be reduced to a single infinite series that can be approximated efficiently. Full article
1516 KiB  
Communication
A Dual PET/MR Imaging Nanoprobe: 124I Labeled Gd3N@C80
by Jianqiao Luo, John D. Wilson, Jianyuan Zhang, Jerry I. Hirsch, Harry C. Dorn, Panos P. Fatouros and Michael D. Shultz
Appl. Sci. 2012, 2(2), 465-478; https://doi.org/10.3390/app2020465 - 10 May 2012
Cited by 22 | Viewed by 8142
Abstract
The current report describes the development of a dual modality tomographic agent for both positron emission tomography and magnetic resonance imaging (PET/MRI). The dual-modality agent in this study was based on a 124I (PET) radiolabeled tri-gadolinium endohedral metallofullerene Gd3N@C80 [...] Read more.
The current report describes the development of a dual modality tomographic agent for both positron emission tomography and magnetic resonance imaging (PET/MRI). The dual-modality agent in this study was based on a 124I (PET) radiolabeled tri-gadolinium endohedral metallofullerene Gd3N@C80 (MRI) nanoprobe platform. The outer surface of the fullerene cage of the Gd3N@C80 metallofullerenes was surface functionalized with carboxyl and hydroxyl groups (f-Gd3N@C80) using previously developed procedures and subsequently iodinated with 124I to produce 124I-f-Gd3N@C80 nanoprobe. Orthotopic tumor-bearing rats were infused intratumorally by convection-enhanced delivery (CED) with the 124I-f-Gd3N@C80 agent and imaged by MRI or micro PET. The anatomical positioning and distribution of the 124I-f-Gd3N@C80 agent were comparable between the MRI and PET scans. The 124I-f-Gd3N@C80­ dual-agent distribution and infusion site within the tumor was clearly evident in both T1- and T2-weighted MR images. The results demonstrate the successful preparation of a dual-modality imaging agent, 124I-f-Gd3N@C80, which could ultimately be used for simultaneous PET/MR imaging. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles: Synthesis, Properties and Applications)
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725 KiB  
Article
Fluorine Based Superhydrophobic Coatings
by Jean-Denis Brassard, D.K. Sarkar and Jean Perron
Appl. Sci. 2012, 2(2), 453-464; https://doi.org/10.3390/app2020453 - 8 May 2012
Cited by 201 | Viewed by 18729
Abstract
Superhydrophobic coatings, inspired by nature, are an emerging technology. These water repellent coatings can be used as solutions for corrosion, biofouling and even water and air drag reduction applications. In this work, synthesis of monodispersive silica nanoparticles of ~120 nm diameter has been [...] Read more.
Superhydrophobic coatings, inspired by nature, are an emerging technology. These water repellent coatings can be used as solutions for corrosion, biofouling and even water and air drag reduction applications. In this work, synthesis of monodispersive silica nanoparticles of ~120 nm diameter has been realized via Stöber process and further functionalized using fluoroalkylsilane (FAS-17) molecules to incorporate the fluorinated groups with the silica nanoparticles in an ethanolic solution. The synthesized fluorinated silica nanoparticles have been spin coated on flat aluminum alloy, silicon and glass substrates. Functionalization of silica nanoparticles with fluorinated groups has been confirmed by Fourier Transform Infrared spectroscopy (FTIR) by showing the presence of C-F and Si-O-Si bonds. The water contact angles and surface roughness increase with the number of spin-coated thin films layers. The critical size of ~119 nm renders aluminum surface superhydrophobic with three layers of coating using as-prepared nanoparticle suspended solution. On the other hand, seven layers are required for a 50 vol.% diluted solution to achieve superhydrophobicity. In both the cases, water contact angles were more than 150°, contact angle hysteresis was less than 2° having a critical roughness value of ~0.700 µm. The fluorinated silica nanoparticle coated surfaces are also transparent and can be used as paint additives to obtain transparent coatings. Full article
(This article belongs to the Special Issue Organo-Fluorine Chemical Science)
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300 KiB  
Article
Further Successes of the Meisenheimer Model
by Jon Baker Baker and Max Muir
Appl. Sci. 2012, 2(2), 443-452; https://doi.org/10.3390/app2020443 - 4 May 2012
Cited by 3 | Viewed by 6008
Abstract
Our simple Meisenheimer model for predicting the principal site for nucleophilic substitution in aromatic perfluorocarbons is further tested on a series of recently published reactions in liquid ammonia primarily from Malykhin and coworkers. The model accurately predicts the experimental results for all of [...] Read more.
Our simple Meisenheimer model for predicting the principal site for nucleophilic substitution in aromatic perfluorocarbons is further tested on a series of recently published reactions in liquid ammonia primarily from Malykhin and coworkers. The model accurately predicts the experimental results for all of the reactions reported further confirming its general applicability. Full article
(This article belongs to the Special Issue Organo-Fluorine Chemical Science)
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6427 KiB  
Review
Ion Beam Formation and Modification of Cobalt Nanoparticles
by David J. Sprouster and Mark C. Ridgway
Appl. Sci. 2012, 2(2), 396-442; https://doi.org/10.3390/app2020396 - 27 Apr 2012
Cited by 25 | Viewed by 8107
Abstract
This article reviews the size-dependent structural properties of ion beam synthesized Co nanoparticles (NPs) and the influence of ion irradiation on the size, shape, phase and structure. The evolution of the aforementioned properties were determined using complementary laboratory- and advanced synchrotron-based techniques, including [...] Read more.
This article reviews the size-dependent structural properties of ion beam synthesized Co nanoparticles (NPs) and the influence of ion irradiation on the size, shape, phase and structure. The evolution of the aforementioned properties were determined using complementary laboratory- and advanced synchrotron-based techniques, including cross-sectional transmission electron microscopy, small-angle X-ray scattering and X-ray absorption spectroscopy. Combining such techniques reveals a rich array of transformations particular to Co NPs. This methodology highlights the effectiveness of ion implantation and ion irradiation procedures as a means of fine tuning NP properties to best suit specific technological applications. Furthermore, our results facilitate a better understanding and aid in identifying the underlying physics particular to this potentially technologically important class of nanomaterials. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles: Synthesis, Properties and Applications)
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1094 KiB  
Article
Electrically Small Resonators for Planar Metamaterial, Microwave Circuit and Antenna Design: A Comparative Analysis
by Miguel Durán-Sindreu, Jordi Naqui, Ferran Paredes, Jordi Bonache and Ferran Martín
Appl. Sci. 2012, 2(2), 375-395; https://doi.org/10.3390/app2020375 - 20 Apr 2012
Cited by 60 | Viewed by 17044
Abstract
Planar metamaterials and many microwave circuits and antennas are designed by means of resonators with dimensions much smaller than the wavelength at their resonance frequency. There are many types of such electrically small resonators, and the main purpose of this paper is to [...] Read more.
Planar metamaterials and many microwave circuits and antennas are designed by means of resonators with dimensions much smaller than the wavelength at their resonance frequency. There are many types of such electrically small resonators, and the main purpose of this paper is to compare them as building blocks for the implementation of microwave components. Aspects such as resonator size, bandwidth, their circuit models when they are coupled to transmission lines (as is usually required), as well as key applications, will be considered. Full article
(This article belongs to the Special Issue Feature Papers)
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248 KiB  
Article
Synthesis of Some New Fluorinated Hexahydroquinoline and Acridinedione Derivatives in Trifluoroethanol
by Cosmas O. Okoro, Mumiye A. Ogunwale and Tasneem Siddiquee
Appl. Sci. 2012, 2(2), 368-374; https://doi.org/10.3390/app2020368 - 18 Apr 2012
Cited by 11 | Viewed by 6713
Abstract
This article describes one-pot synthesis of new fluorinated hexahydroquinoline derivatives via unsymmetric Hantzsch reaction involving 5-trifluoromethyl-1,3-cyclohexanedione, aldehydes, acetoacetate ester, and ammonium acetate in trifluoroethanol (TFE). The reaction is simple and rapid with high yield. Full article
(This article belongs to the Special Issue Organo-Fluorine Chemical Science)
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521 KiB  
Review
An Environmentally Friendly Class of Fluoropolyether: α,ω-Dialkoxyfluoropolyethers
by Menghua Wu, Walter Navarrini, Gianfranco Spataro, Francesco Venturini and Maurizio Sansotera
Appl. Sci. 2012, 2(2), 351-367; https://doi.org/10.3390/app2020351 - 11 Apr 2012
Cited by 15 | Viewed by 7511
Abstract
The α,ω-dialkoxyfluoropolyethers (DA-FPEs) characterized by the structure RHO(CF2CF2O)n(CF2O)mRH have been developed as a new class of environmentally friendly hydrofluoroethers (HFEs) suitable as solvents, long-term refrigerants, cleaning fluids, and heat transfer [...] Read more.
The α,ω-dialkoxyfluoropolyethers (DA-FPEs) characterized by the structure RHO(CF2CF2O)n(CF2O)mRH have been developed as a new class of environmentally friendly hydrofluoroethers (HFEs) suitable as solvents, long-term refrigerants, cleaning fluids, and heat transfer fluids. Synthetic methodologies for DA-FPEs described here consist of radical-initiated oxypolymerization of olefin, peroxy-elimination reaction in peroxidic perfluoropolyethers (P-PFPEs) and further chemical modification of α,ω-diacylfluoride PFPE. The physical properties of selected α,ω-dimethoxyfluoropolyethers (DM-FPEs) have been evaluated and compared with analogous hydrofluoropolyethers (HFPEs) having -OCF2H as end-groups. Atmospheric implications and global warming potentials (GWPs) of selected DA-FPEs are also considered. Full article
(This article belongs to the Special Issue Organo-Fluorine Chemical Science)
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355 KiB  
Article
Magnetic Nanoparticles Aggregation in Magnetic Gel Studied by Electron Magnetic Resonance (EMR)
by Olga N. Sorokina, Alexander L. Kovarski, Marina A. Lagutina, Sergey A. Dubrovskii and Fridrikh S. Dzheparov
Appl. Sci. 2012, 2(2), 342-350; https://doi.org/10.3390/app2020342 - 10 Apr 2012
Cited by 9 | Viewed by 6266
Abstract
Aggregation of magnetic nanoparticles immobilized in polymer gels was studied by ferromagnetic resonance and paramagnetic sensor techniques. Ferromagnetic resonance spectra of magnetic gels prepared in the presence of external magnetic field of 1.5 kG were compared to the spectra of gels synthesized in [...] Read more.
Aggregation of magnetic nanoparticles immobilized in polymer gels was studied by ferromagnetic resonance and paramagnetic sensor techniques. Ferromagnetic resonance spectra of magnetic gels prepared in the presence of external magnetic field of 1.5 kG were compared to the spectra of gels synthesized in the absence of a magnetic field. Application of a magnetic field led to formation of linear aggregates of magnetic particles in the polymer matrix. The aggregates did not come apart after the field was switched off. The fraction of aggregated particles (of 62(6)%) and aspect ratio (elongation) of the aggregates (12.6(1.3)) was determined using paramagnetic sensor technique. Full article
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294 KiB  
Article
Application of Liquid-Phase Direct Fluorination: Novel Synthetic Methods for a Polyfluorinated Coating Material and a Monomer of a Perfluorinated Polymer Electrolyte Membrane
by Takashi Okazoe, Daisuke Shirakawa and Koichi Murata
Appl. Sci. 2012, 2(2), 327-341; https://doi.org/10.3390/app2020327 - 10 Apr 2012
Cited by 15 | Viewed by 8453
Abstract
A new polyfluorinated anti-staining coating material CF3O(CF2CF2O)xCF2-CONHCH2CH2CH2Si(OCH3)3 has been developed by utilizing the PERFECT method, which employs a liquid-phase direct fluorination reaction with elemental [...] Read more.
A new polyfluorinated anti-staining coating material CF3O(CF2CF2O)xCF2-CONHCH2CH2CH2Si(OCH3)3 has been developed by utilizing the PERFECT method, which employs a liquid-phase direct fluorination reaction with elemental fluorine as a key step. Direct fluorination of a partially-fluorinated ester, which was prepared from a non-fluorinated poly(ethylene glycol) and a perfluorinated acyl fluoride, followed by methanolysis, gave the perfluorinated corresponding compound, which was led to the coating material for surface treating agents, and the methyl ester of the starting perfluorinated acyl fluoride. Application to the synthesis of a new perfluorinated bifunctional sulfonate monomer CF2=CFOCF2CF2CF2OCF(CF2SO2F)2 for polymer electrolyte membranes (PEMs) of fuel cells was also developed. Full article
(This article belongs to the Special Issue Organo-Fluorine Chemical Science)
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396 KiB  
Article
Anomalous Magnetization Enhancement and Frustration in the Internal Magnetic Order on (Fe0.69Co0.31)B0.4 Nanoparticles
by Belén Molina-Concha, Roberto D. Zysler and Héctor Romero
Appl. Sci. 2012, 2(2), 315-326; https://doi.org/10.3390/app2020315 - 2 Apr 2012
Cited by 6 | Viewed by 7268
Abstract
We have studied the internal magnetic order of 3-nm (Fe0.69Co0.31)0.6B0.4 amorphous nanoparticles. These nanoparticles were dispersed in a non-magnetic matrix (non-interacting nanoparticles) to contrast them with the powder samples, where strong interparticle interactions are present. In [...] Read more.
We have studied the internal magnetic order of 3-nm (Fe0.69Co0.31)0.6B0.4 amorphous nanoparticles. These nanoparticles were dispersed in a non-magnetic matrix (non-interacting nanoparticles) to contrast them with the powder samples, where strong interparticle interactions are present. In similar fashion to the bulk alloy, this system exhibits a saturation magnetization maximum as a function of Fe composition near 69 at% Fe for the powder and dispersed samples at all temperatures. The saturation magnetization (MS) of the dispersed sample shows anomalous behavior, revealing frustration in the internal magnetic order of the particles. Unexpectedly, the MS of the non-interacting sample at low temperatures is larger than the corresponding bulk alloy or the calculated value of MS for the same Fe-Co composition. By contrast, the powder sample has low MS values and it is approximately constant in temperature. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles: Synthesis, Properties and Applications)
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3244 KiB  
Article
Effects of Superparamagnetic Nanoparticle Clusters on the Polymerase Chain Reaction
by Toshiaki Higashi, Hiroaki Minegishi, Yutaka Nagaoka, Takahiro Fukuda, Akinobu Echigo, Ron Usami, Toru Maekawa and Tatsuro Hanajiri
Appl. Sci. 2012, 2(2), 303-314; https://doi.org/10.3390/app2020303 - 2 Apr 2012
Cited by 15 | Viewed by 7212
Abstract
The polymerase chain reaction (PCR) method is widely used for the reproduction and amplification of specific DNA segments, and a novel PCR method using nanomaterials such as gold nanoparticles has recently been reported. This paper reports on the effects of superparamagnetic nanoparticles on [...] Read more.
The polymerase chain reaction (PCR) method is widely used for the reproduction and amplification of specific DNA segments, and a novel PCR method using nanomaterials such as gold nanoparticles has recently been reported. This paper reports on the effects of superparamagnetic nanoparticles on PCR amplification without an external magnetic field, and clarifies the mechanism behind the effects of superparamagnetic particle clusters on PCR efficiency by estimating the structures of such clusters in PCR. It was found that superparamagnetic nanoparticles tend to inhibit PCR amplification depending on the structure of the magnetic nanoparticle clusters. The paper also clarifies that Taq polymerase is captured in the spaces formed among magnetic nanoparticle clusters, and that it is captured more efficiently as a result of their motion from heat treatment in PCR thermal cycles. Consequently, Taq polymerase that should be used in PCR is reduced in the PCR solution. These outcomes will be applied to novel PCR techniques using magnetic particles in an external magnetic field. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles: Synthesis, Properties and Applications)
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628 KiB  
Review
Silicon-[18F]Fluorine Radiochemistry: Basics, Applications and Challenges
by Carmen Wängler, Alexey Kostikov, Jun Zhu, Joshua Chin, Björn Wängler and Ralf Schirrmacher
Appl. Sci. 2012, 2(2), 277-302; https://doi.org/10.3390/app2020277 - 28 Mar 2012
Cited by 43 | Viewed by 12627
Abstract
Silicon-[18F]fluorine (Si-18F) radiochemistry has recently emerged alongside other unconventional approaches such as aluminum-18F and boron-18F based labeling strategies, reshaping the landscape of modern 18F-radiochemistry. All these novel methodologies are driven by the demand for [...] Read more.
Silicon-[18F]fluorine (Si-18F) radiochemistry has recently emerged alongside other unconventional approaches such as aluminum-18F and boron-18F based labeling strategies, reshaping the landscape of modern 18F-radiochemistry. All these novel methodologies are driven by the demand for more convenient 18F-labeling procedures to further disseminate one of the most sophisticated imaging technologies, Positron Emission Tomography (PET). The PET methodology requires special radionuclides such as 18F (one of the most prominent examples) to be introduced into bioactive molecules. Si-18F radiochemistry contributed greatly towards the development of new radiopharmaceuticals for PET imaging. Herein, we describe the radiochemical basics of Si-18F bond formation, the application of Si-18F tracers for PET imaging, and additionally, the inherent chemical intricacies of this methodology. Full article
(This article belongs to the Special Issue Organo-Fluorine Chemical Science)
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1377 KiB  
Article
Magnetically Separable Base Catalysts: Heterogeneous Catalysis vs. Quasi-Homogeneous Catalysis
by Raed Abu-Reziq and Howard Alper
Appl. Sci. 2012, 2(2), 260-276; https://doi.org/10.3390/app2020260 - 26 Mar 2012
Cited by 21 | Viewed by 8586
Abstract
The synthesis of magnetically separable quasi-homogeneous base catalyst and heterogeneous base catalyst is described. The quasi-homogeneous catalyst is achieved by supporting silane monomers functionalized with different amine groups directly on the surface of magnetite nanoparticles. The heterogeneous catalyst is prepared via [...] Read more.
The synthesis of magnetically separable quasi-homogeneous base catalyst and heterogeneous base catalyst is described. The quasi-homogeneous catalyst is achieved by supporting silane monomers functionalized with different amine groups directly on the surface of magnetite nanoparticles. The heterogeneous catalyst is prepared via a sol-gel process in which silane monomers containing different amine groups are copolymerized with tetraethoxysilane in the presence of magnetite nanoparticles functionalized with ionic liquid moieties. The reactivity of the quasi-homogeneous and the heterogeneous base catalysts is compared in the nitroaldol condensation. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles: Synthesis, Properties and Applications)
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1250 KiB  
Review
Nucleic Acid Based Fluorinated Derivatives: New Tools for Biomedical Applications
by Christel Dolain, Amit Patwa, Guilhem Godeau and Philippe Barthélémy
Appl. Sci. 2012, 2(2), 245-259; https://doi.org/10.3390/app2020245 - 23 Mar 2012
Cited by 24 | Viewed by 12431
Abstract
Nucleic acid-based fluorinated derivatives, e.g., nucleosides or oligonucleotides connected to highly fluorinated chains or labeled with one or more fluorine atoms, have been investigated recently due to their high potential for biomedical applications. This review deals with recent works on nucleoside and oligonucleotide [...] Read more.
Nucleic acid-based fluorinated derivatives, e.g., nucleosides or oligonucleotides connected to highly fluorinated chains or labeled with one or more fluorine atoms, have been investigated recently due to their high potential for biomedical applications. This review deals with recent works on nucleoside and oligonucleotide fluorocarbon amphiphiles as well as with properties and applications of fluorine-labeled oligonucleotide analogues. Full article
(This article belongs to the Special Issue Organo-Fluorine Chemical Science)
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