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Materials, Volume 7, Issue 12 (December 2014), Pages 7615-8212

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Open AccessArticle Super Dielectric Materials
Materials 2014, 7(12), 8197-8212; https://doi.org/10.3390/ma7128197
Received: 6 November 2014 / Revised: 26 November 2014 / Accepted: 12 December 2014 / Published: 22 December 2014
Cited by 8 | PDF Full-text (984 KB) | HTML Full-text | XML Full-text
Abstract
Evidence is provided here that a class of materials with dielectric constants greater than 105 at low frequency (<10−2 Hz), herein called super dielectric materials (SDM), can be generated readily from common, inexpensive materials. Specifically it is demonstrated that high surface
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Evidence is provided here that a class of materials with dielectric constants greater than 105 at low frequency (<10−2 Hz), herein called super dielectric materials (SDM), can be generated readily from common, inexpensive materials. Specifically it is demonstrated that high surface area alumina powders, loaded to the incipient wetness point with a solution of boric acid dissolved in water, have dielectric constants, near 0 Hz, greater than 4 × 108 in all cases, a remarkable increase over the best dielectric constants previously measured for energy storage capabilities, ca. 1 × 104. It is postulated that any porous, electrically insulating material (e.g., high surface area powders of silica, titania, etc.), filled with a liquid containing a high concentration of ionic species will potentially be an SDM. Capacitors created with the first generated SDM dielectrics (alumina with boric acid solution), herein called New Paradigm Super (NPS) capacitors display typical electrostatic capacitive behavior, such as increasing capacitance with decreasing thickness, and can be cycled, but are limited to a maximum effective operating voltage of about 0.8 V. A simple theory is presented: Water containing relatively high concentrations of dissolved ions saturates all, or virtually all, the pores (average diameter 500 Å) of the alumina. In an applied field the positive ionic species migrate to the cathode end, and the negative ions to the anode end of each drop. This creates giant dipoles with high charge, hence leading to high dielectric constant behavior. At about 0.8 V, water begins to break down, creating enough ionic species to “short” the individual water droplets. Potentially NPS capacitor stacks can surpass “supercapacitors” in volumetric energy density. Full article
(This article belongs to the Section Energy Materials)
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Open AccessCommunication Improving the Efficiency of Organic Solar Cells upon Addition of Polyvinylpyridine
Materials 2014, 7(12), 8189-8196; https://doi.org/10.3390/ma7128189
Received: 3 November 2014 / Accepted: 12 December 2014 / Published: 22 December 2014
Cited by 3 | PDF Full-text (630 KB) | HTML Full-text | XML Full-text
Abstract
We report on the efficiency improvement of organic solar cells (OPVs) based on the low energy gap polyfluorene derivative, APFO-3, and the soluble C60 fullerene PCBM, upon addition of a residual amount of poly (4-vinylpyridine) (PVP). We find that the addition of
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We report on the efficiency improvement of organic solar cells (OPVs) based on the low energy gap polyfluorene derivative, APFO-3, and the soluble C60 fullerene PCBM, upon addition of a residual amount of poly (4-vinylpyridine) (PVP). We find that the addition of 1% by weight of PVP with respect to the APFO-3 content leads to an increase of efficiency from 2.4% to 2.9%. Modifications in the phase separation details of the active layer were investigated as a possible origin of the efficiency increase. At high concentrations of PVP, the blend morphology is radically altered as observed by Atomic Force Microscopy. Although the use of low molecular weight additives is a routine method to improve OPVs efficiency, this report shows that inert polymers, in terms of optical and charge transport properties, may also improve the performance of polymer-based solar cells. Full article
(This article belongs to the Section Energy Materials)
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Open AccessReview Biocompatibility of Advanced Manufactured Titanium Implants—A Review
Materials 2014, 7(12), 8168-8188; https://doi.org/10.3390/ma7128168
Received: 25 August 2014 / Revised: 5 October 2014 / Accepted: 8 December 2014 / Published: 19 December 2014
Cited by 58 | PDF Full-text (879 KB) | HTML Full-text | XML Full-text
Abstract
Titanium (Ti) and its alloys may be processed via advanced powder manufacturing routes such as additive layer manufacturing (or 3D printing) or metal injection moulding. This field is receiving increased attention from various manufacturing sectors including the medical devices sector. It is possible
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Titanium (Ti) and its alloys may be processed via advanced powder manufacturing routes such as additive layer manufacturing (or 3D printing) or metal injection moulding. This field is receiving increased attention from various manufacturing sectors including the medical devices sector. It is possible that advanced manufacturing techniques could replace the machining or casting of metal alloys in the manufacture of devices because of associated advantages that include design flexibility, reduced processing costs, reduced waste, and the opportunity to more easily manufacture complex or custom-shaped implants. The emerging advanced manufacturing approaches of metal injection moulding and additive layer manufacturing are receiving particular attention from the implant fabrication industry because they could overcome some of the difficulties associated with traditional implant fabrication techniques such as titanium casting. Using advanced manufacturing, it is also possible to produce more complex porous structures with improved mechanical performance, potentially matching the modulus of elasticity of local bone. While the economic and engineering potential of advanced manufacturing for the manufacture of musculo-skeletal implants is therefore clear, the impact on the biocompatibility of the materials has been less investigated. In this review, the capabilities of advanced powder manufacturing routes in producing components that are suitable for biomedical implant applications are assessed with emphasis placed on surface finishes and porous structures. Given that biocompatibility and host bone response are critical determinants of clinical performance, published studies of in vitro and in vivo research have been considered carefully. The review concludes with a future outlook on advanced Ti production for biomedical implants using powder metallurgy. Full article
(This article belongs to the Section Biomaterials)
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Open AccessArticle Anodization Mechanism on SiC Nanoparticle Reinforced Al Matrix Composites Produced by Power Metallurgy
Materials 2014, 7(12), 8151-8167; https://doi.org/10.3390/ma7128151
Received: 8 October 2014 / Revised: 13 November 2014 / Accepted: 11 December 2014 / Published: 19 December 2014
Cited by 3 | PDF Full-text (2764 KB) | HTML Full-text | XML Full-text
Abstract
Specimens of aluminum-based composites reinforced by silicon carbide nanoparticles (Al/SiCnp) produced by powder metallurgy (PM) were anodized under voltage control in tartaric-sulfuric acid (TSA). In this work, the influence of the amount of SiCnp on the film growth during anodizing
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Specimens of aluminum-based composites reinforced by silicon carbide nanoparticles (Al/SiCnp) produced by powder metallurgy (PM) were anodized under voltage control in tartaric-sulfuric acid (TSA). In this work, the influence of the amount of SiCnp on the film growth during anodizing was investigated. The current density versus time response and the morphology of the porous alumina film formed at the composite surface are compared to those concerning a commercial aluminum alloy (AA1050) anodized under the same conditions. The processing method of the aluminum alloys influences the efficiency of the anodizing process, leading to a lower thicknesses for the unreinforced Al-PM alloy regarding the AA1050. The current density versus time response is strongly dependent on the amount of SiCnp. The current peaks and the steady-state current density recorded at each voltage step increases with the SiCnp volume fraction due to the oxidation of the SiCnp. The formation mechanism of the anodic film on Al/SiCnp composites is different from that occurring in AA1050, partly due the heterogeneous distribution of the reinforcement particles in the metallic matrix, but also to the entrapment of SiCnp in the anodic film. Full article
(This article belongs to the Section Advanced Composites)
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Open AccessArticle Properties Characterization of Chemically Modified Hemp Hurds
Materials 2014, 7(12), 8131-8150; https://doi.org/10.3390/ma7128131
Received: 3 October 2014 / Revised: 7 November 2014 / Accepted: 5 December 2014 / Published: 17 December 2014
Cited by 24 | PDF Full-text (1296 KB) | HTML Full-text | XML Full-text
Abstract
The effect of chemical treatment of hemp hurds slices in three solutions (EDTA (Ethylenediaminetetraacetic acid), NaOH and Ca(OH)2) on the properties of natural material was discussed in this paper. Changes in the morphology, chemical composition and structure as well as thermal
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The effect of chemical treatment of hemp hurds slices in three solutions (EDTA (Ethylenediaminetetraacetic acid), NaOH and Ca(OH)2) on the properties of natural material was discussed in this paper. Changes in the morphology, chemical composition and structure as well as thermal stability of hemp hurds before and after their modification were investigated by using FTIR (Fourier transform infrared spectroscopy), XRD (X-ray powder diffraction analysis) and TG (thermogravimetry)/DSC (differential scanning calorimetry). Size exclusion chromatography (SEC) measurements were used for determination of degree of cellulose polymerization of hemp hurd samples. Chemical modification is related to the partial removal of non-cellulosic components of lignin, hemicellulose and pectin as well as waxes from the surface of hemp hurd slices. Another effect of the chemical treatment applied is connected with increasing the crystallinity index of cellulose determined by FTIR and XRD methods. Decrease in degree of cellulose polymerization and polydispersity index in chemically modified hemp hurds compared to the original sample was observed. Increase in thermal stability of treated hemp hurd was found. The most significant changes were observed in alkaline treated hemp hurds by NaOH. Full article
(This article belongs to the Section Advanced Composites)
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Open AccessArticle Metal Phosphate-Supported Pt Catalysts for CO Oxidation
Materials 2014, 7(12), 8105-8130; https://doi.org/10.3390/ma7128105
Received: 3 November 2014 / Revised: 23 November 2014 / Accepted: 3 December 2014 / Published: 17 December 2014
Cited by 22 | PDF Full-text (1849 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Oxides (such as SiO2, TiO2, ZrO2, Al2O3, Fe2O3, CeO2) have often been used to prepare supported Pt catalysts for CO oxidation and other reactions, whereas metal phosphate-supported
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Oxides (such as SiO2, TiO2, ZrO2, Al2O3, Fe2O3, CeO2) have often been used to prepare supported Pt catalysts for CO oxidation and other reactions, whereas metal phosphate-supported Pt catalysts for CO oxidation were rarely reported. Metal phosphates are a family of metal salts with high thermal stability and acid-base properties. Hydroxyapatite (Ca10(PO4)6(OH)2, denoted as Ca-P-O here) also has rich hydroxyls. Here we report a series of metal phosphate-supported Pt (Pt/M-P-O, M = Mg, Al, Ca, Fe, Co, Zn, La) catalysts for CO oxidation. Pt/Ca-P-O shows the highest activity. Relevant characterization was conducted using N2 adsorption-desorption, inductively coupled plasma (ICP) atomic emission spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), CO2 temperature-programmed desorption (CO2-TPD), X-ray photoelectron spectroscopy (XPS), and H2 temperature-programmed reduction (H2-TPR). This work furnishes a new catalyst system for CO oxidation and other possible reactions. Full article
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Open AccessArticle Poly(2,5-bis(N-Methyl-N-Hexylamino)Phenylene Vinylene) (BAM-PPV) as Pretreatment Coating for Aerospace Applications: Laboratory and Field Studies
Materials 2014, 7(12), 8088-8104; https://doi.org/10.3390/ma7128088
Received: 27 June 2014 / Revised: 18 November 2014 / Accepted: 4 December 2014 / Published: 17 December 2014
Cited by 1 | PDF Full-text (560 KB) | HTML Full-text | XML Full-text
Abstract
In this study, an electroactive polymer (EAP), poly(2,5-bis(N-methyl-N-hexylamino)phenylene vinylene) (BAM-PPV) was investigated as a potential alternative surface pretreatment for hexavalent chromium (Cr(VI))-based aerospace coatings. BAM-PPV was tested as a pretreatment coating on an aerospace aluminum alloy (AA2024-T3) substrate in
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In this study, an electroactive polymer (EAP), poly(2,5-bis(N-methyl-N-hexylamino)phenylene vinylene) (BAM-PPV) was investigated as a potential alternative surface pretreatment for hexavalent chromium (Cr(VI))-based aerospace coatings. BAM-PPV was tested as a pretreatment coating on an aerospace aluminum alloy (AA2024-T3) substrate in combination with a non-Cr(VI) epoxy primer and a polyurethane Advanced Performance Coating (APC) topcoat. This testing was undertaken to determine BAM-PPV’s adhesion, corrosion-inhibition, compatibility and survivability in laboratory testing and during outdoor field-testing. BAM-PPV showed excellent adhesion and acceptable corrosion performance in laboratory testing. The BAM-PPV aerospace coating system (BAM-PPV, non-Cr(VI) epoxy primer and polyurethane APC topcoat) was field tested for one year on the rear hatch door of the United States Air Force C-5 cargo plane. After one year of field testing there was no evidence of delamination or corrosion of the BAM-PPV aerospace coating system. Full article
(This article belongs to the Special Issue Corrosion of Materials)
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Open AccessArticle Thermophysical and Mechanical Properties of Hardened Cement Paste with Microencapsulated Phase Change Materials for Energy Storage
Materials 2014, 7(12), 8070-8087; https://doi.org/10.3390/ma7128070
Received: 7 August 2014 / Revised: 3 December 2014 / Accepted: 3 December 2014 / Published: 16 December 2014
Cited by 13 | PDF Full-text (1247 KB) | HTML Full-text | XML Full-text
Abstract
In this research, structural-functional integrated cement-based materials were prepared by employing cement paste and a microencapsulated phase change material (MPCM) manufactured using urea-formaldehyde resin as the shell and paraffin as the core material. The encapsulation ratio of the MPCM could reach up to
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In this research, structural-functional integrated cement-based materials were prepared by employing cement paste and a microencapsulated phase change material (MPCM) manufactured using urea-formaldehyde resin as the shell and paraffin as the core material. The encapsulation ratio of the MPCM could reach up to 91.21 wt%. Thermal energy storage cement pastes (TESCPs) incorporated with different MPCM contents (5%, 10%, 15%, 20% and 25% by weight of cement) were developed, and their thermal and mechanical properties were studied. The results showed that the total energy storage capacity of the hardened cement specimens with MPCM increased by up to 3.9-times compared with that of the control cement paste. The thermal conductivity at different temperature levels (35–36 °C, 55–56 °C and 72–74 °C) decreased with the increase of MPCM content, and the decrease was the highest when the temperature level was 55–56 °C. Moreover, the compressive strength, flexural strength and density of hardened cement paste decreased with the increase in MPCM content linearly. Among the evaluated properties, the compressive strength of TESCPs had a larger and faster degradation with the increase of MPCM content. Full article
(This article belongs to the Section Energy Materials)
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Open AccessArticle Annealing Effects in Twin-Roll Cast AA8006 Aluminium Sheets Processed by Accumulative Roll-Bonding
Materials 2014, 7(12), 8058-8069; https://doi.org/10.3390/ma7128058
Received: 10 October 2014 / Revised: 28 November 2014 / Accepted: 7 December 2014 / Published: 15 December 2014
Cited by 3 | PDF Full-text (2987 KB) | HTML Full-text | XML Full-text
Abstract
Ultrafine grained sheets were prepared from a twin-roll cast AA8006 aluminium alloy using accumulative roll-bonding process at room temperature. The evolution of microstructure of sheets after three accumulative roll-bonding passes during isochronal annealing with a constant step of 20 °C/20 min was studied
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Ultrafine grained sheets were prepared from a twin-roll cast AA8006 aluminium alloy using accumulative roll-bonding process at room temperature. The evolution of microstructure of sheets after three accumulative roll-bonding passes during isochronal annealing with a constant step of 20 °C/20 min was studied by light and electron microscopy. The influence of the resulting microstructure on mechanical properties was monitored by microhardness measurements. The microhardness increases when the material is annealed up to 160 °C. Above this temperature a fast drop of microhardness occurs followed by a negligible variation at annealing temperatures exceeding 300 °C. In order to map continuously the microstructure changes during annealing, the in situ TEM experiments in the heating stage were performed as a supplement to post-mortem TEM observations. Full article
(This article belongs to the Section Structure Analysis and Characterization)
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Open AccessArticle Adsorption of Azo-Dye Orange II from Aqueous Solutions Using a Metal-Organic Framework Material: Iron- Benzenetricarboxylate
Materials 2014, 7(12), 8037-8057; https://doi.org/10.3390/ma7128037
Received: 30 October 2014 / Revised: 19 November 2014 / Accepted: 3 December 2014 / Published: 12 December 2014
Cited by 39 | PDF Full-text (1578 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A Metal-Organic Framework (MOF), iron-benzenetricarboxylate (Fe(BTC)), has been studied for the adsorptive removal of azo-dye Orange II from aqueous solutions, where the effect of various parameters was tested and isotherm and kinetic models were suggested. The adsorption capacities of Fe(BTC) were much higher
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A Metal-Organic Framework (MOF), iron-benzenetricarboxylate (Fe(BTC)), has been studied for the adsorptive removal of azo-dye Orange II from aqueous solutions, where the effect of various parameters was tested and isotherm and kinetic models were suggested. The adsorption capacities of Fe(BTC) were much higher than those of an activated carbon. The experimental data can be best described by the Langmuir isotherm model (R2 > 0.997) and revealed the ability of Fe(BTC) to adsorb 435 mg of Orange II per gram of adsorbent at the optimal conditions. The kinetics of Orange II adsorption followed a pseudo-second-order kinetic model, indicating the coexistence of physisorption and chemisorption, with intra-particle diffusion being the rate controlling step. The thermodynamic study revealed that the adsorption of Orange II was feasible, spontaneous and exothermic process (−25.53 kJ·mol−1). The high recovery of the dye showed that Fe(BTC) can be employed as an effective and reusable adsorbent for the removal of Orange II from aqueous solutions and showed the economic interest of this adsorbent material for environmental purposes. Full article
(This article belongs to the Section Porous Materials)
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Open AccessArticle Enhanced Photocatalytic Degradation of Methyl Orange Dye under the Daylight Irradiation over CN-TiO2 Modified with OMS-2
Materials 2014, 7(12), 8024-8036; https://doi.org/10.3390/ma7128024
Received: 22 October 2014 / Revised: 2 December 2014 / Accepted: 9 December 2014 / Published: 12 December 2014
Cited by 10 | PDF Full-text (590 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this study, CN-TiO2 was modified with cryptomelane octahedral molecular sieves (OMS-2) by the sol-gel method based on the self-assembly technique to enhance its photocatalytic activity under the daylight irradiation. The synthesized samples were characterized by X-ray diffraction (XRD), UV-vis spectroscopy, Fourier
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In this study, CN-TiO2 was modified with cryptomelane octahedral molecular sieves (OMS-2) by the sol-gel method based on the self-assembly technique to enhance its photocatalytic activity under the daylight irradiation. The synthesized samples were characterized by X-ray diffraction (XRD), UV-vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and porosimeter analysis. The results showed that the addition of OMS-2 in the sol lead to higher Brunauer-Emmett-Teller (BET) surface area, pore volume, porosity of particle after heat treatment and the specific surface area, porosity, crystallite size and pore size distribution could be controlled by adjusting the calcination temperature. Compared to the CN-TiO2-400 sample, CN-TiO2/OMS-2-400 exhibited greater red shift in absorption edge of samples in visible region due to the OMS-2 coated. The enhancement of photocatalytic activity of CN-TiO2/OMS-2 composite photocatalyst was subsequently evaluated for the degradation of the methyl orange dye under the daylight irradiation in water. The results showed that the methyl orange dye degradation rate reach to 37.8% for the CN-TiO2/OMS-2-400 sample under the daylight irradiation for 5 h, which was higher than that of reference sample. The enhancement in daylight photocatalytic activities of the CN-TiO2/OMS samples could be attributed to the synergistic effects of OMS-2 coated, larger surface area and red shift in adsorption edge of the prepared sample. Full article
(This article belongs to the Special Issue Photocatalytic Materials)
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Open AccessArticle Preparation of Biodiesel from Soybean Catalyzed by Basic Ionic Liquids [Hnmm]OH
Materials 2014, 7(12), 8012-8023; https://doi.org/10.3390/ma7128012
Received: 30 October 2014 / Revised: 13 November 2014 / Accepted: 2 December 2014 / Published: 11 December 2014
Cited by 7 | PDF Full-text (570 KB) | HTML Full-text | XML Full-text
Abstract
A morpholine alkaline basic ionic liquid (IL) 1-butyl-3-methyl morpholine hydroxide ([Hnmm]OH) was synthesized and characterized by 1H NMR and FT-IR. [Hnmm]OH is highly active in catalyzing the synthesis of biodiesel from the reaction of methanol with soybean oil. The influence of the
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A morpholine alkaline basic ionic liquid (IL) 1-butyl-3-methyl morpholine hydroxide ([Hnmm]OH) was synthesized and characterized by 1H NMR and FT-IR. [Hnmm]OH is highly active in catalyzing the synthesis of biodiesel from the reaction of methanol with soybean oil. The influence of the reaction conditions, including the [Hnmm]OH catalyst amount, the molar ratio of methanol to soybean oil, reaction temperature and time, was investigated. Moreover, the pH and thermal stability of the catalyst was studied. The catalytic activity was affected by its alkalinity. The optimum reaction conditions were found as [Hnmm]OH amount of 4% (mass fraction), the methanol to soybean oil molar ratio of 8, temperature 70 °C and reaction time 1.5 h, the yield of Biodiesel reached 97.0%, and exhibits high stability upon recycling, the yield of Biodiesel is still more than 90% even after being reused for five times. A great advantage of using ILs is that it is very easy to separate the final products. After the reaction, a biphasic system was obtained. The top phase contains biodiesel and a little bit of methanol. Pure biodiesel can be isolated by vacuum evacuating the methanol. The bottom phase contains methanol, glycerol and ILs. Pure glycerol can be obtained simply by distillation. After distillation, pure ILs was obtained, which can be used directly for another reaction. The as prepared biodiesel shows very appealing properties. Full article
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Open AccessArticle Process-time Optimization of Vacuum Degassing Using a Genetic Alloy Design Approach
Materials 2014, 7(12), 7997-8011; https://doi.org/10.3390/ma7127997
Received: 29 September 2014 / Revised: 23 November 2014 / Accepted: 3 December 2014 / Published: 10 December 2014
Cited by 3 | PDF Full-text (1132 KB) | HTML Full-text | XML Full-text
Abstract
This paper demonstrates the use of a new model consisting of a genetic algorithm in combination with thermodynamic calculations and analytical process models to minimize the processing time during a vacuum degassing treatment of liquid steel. The model sets multiple simultaneous targets for
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This paper demonstrates the use of a new model consisting of a genetic algorithm in combination with thermodynamic calculations and analytical process models to minimize the processing time during a vacuum degassing treatment of liquid steel. The model sets multiple simultaneous targets for final S, N, O, Si and Al levels and uses the total slag mass, the slag composition, the steel composition and the start temperature as optimization variables. The predicted optimal conditions agree well with industrial practice. For those conditions leading to the shortest process time the target compositions for S, N and O are reached almost simultaneously. Full article
(This article belongs to the Special Issue Steels)
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Open AccessReview Determination and Quantification of Molecular Interactions in Protein Films: A Review
Materials 2014, 7(12), 7975-7996; https://doi.org/10.3390/ma7127975
Received: 15 September 2014 / Revised: 6 November 2014 / Accepted: 27 November 2014 / Published: 10 December 2014
Cited by 49 | PDF Full-text (769 KB) | HTML Full-text | XML Full-text
Abstract
Protein based films are nowadays also prepared with the aim of replacing expensive, crude oil-based polymers as environmentally friendly and renewable alternatives. The protein structure determines the ability of protein chains to form intra- and intermolecular bonds, whereas the degree of cross-linking depends
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Protein based films are nowadays also prepared with the aim of replacing expensive, crude oil-based polymers as environmentally friendly and renewable alternatives. The protein structure determines the ability of protein chains to form intra- and intermolecular bonds, whereas the degree of cross-linking depends on the amino acid composition and molecular weight of the protein, besides the conditions used in film preparation and processing. The functionality varies significantly depending on the type of protein and affects the resulting film quality and properties. This paper reviews the methods used in examination of molecular interactions in protein films and discusses how these intermolecular interactions can be quantified. The qualitative determination methods can be distinguished by structural analysis of solutions (electrophoretic analysis, size exclusion chromatography) and analysis of solid films (spectroscopy techniques, X-ray scattering methods). To quantify molecular interactions involved, two methods were found to be the most suitable: protein film swelling and solubility. The importance of non-covalent and covalent interactions in protein films can be investigated using different solvents. The research was focused on whey protein, whereas soy protein and wheat gluten were included as further examples of proteins. Full article
(This article belongs to the Section Structure Analysis and Characterization)
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Open AccessReview Laser Peening Process and Its Impact on Materials Properties in Comparison with Shot Peening and Ultrasonic Impact Peening
Materials 2014, 7(12), 7925-7974; https://doi.org/10.3390/ma7127925
Received: 17 October 2014 / Revised: 18 November 2014 / Accepted: 27 November 2014 / Published: 10 December 2014
Cited by 50 | PDF Full-text (3579 KB) | HTML Full-text | XML Full-text
Abstract
The laser shock peening (LSP) process using a Q-switched pulsed laser beam for surface modification has been reviewed. The development of the LSP technique and its numerous advantages over the conventional shot peening (SP) such as better surface finish, higher depths of residual
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The laser shock peening (LSP) process using a Q-switched pulsed laser beam for surface modification has been reviewed. The development of the LSP technique and its numerous advantages over the conventional shot peening (SP) such as better surface finish, higher depths of residual stress and uniform distribution of intensity were discussed. Similar comparison with ultrasonic impact peening (UIP)/ultrasonic shot peening (USP) was incorporated, when possible. The generation of shock waves, processing parameters, and characterization of LSP treated specimens were described. Special attention was given to the influence of LSP process parameters on residual stress profiles, material properties and structures. Based on the studies so far, more fundamental understanding is still needed when selecting optimized LSP processing parameters and substrate conditions. A summary of the parametric studies of LSP on different materials has been presented. Furthermore, enhancements in the surface micro and nanohardness, elastic modulus, tensile yield strength and refinement of microstructure which translates to increased fatigue life, fretting fatigue life, stress corrosion cracking (SCC) and corrosion resistance were addressed. However, research gaps related to the inconsistencies in the literature were identified. Current status, developments and challenges of the LSP technique were discussed. Full article
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