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Materials, Volume 8, Issue 1 (January 2015) – 24 articles , Pages 1-378

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566 KiB  
Article
Sorption Isotherm of Southern Yellow Pine—High Density Polyethylene Composites
by Feihong Liu, Guangping Han, Wanli Cheng and Qinglin Wu
Materials 2015, 8(1), 368-378; https://doi.org/10.3390/ma8010368 - 20 Jan 2015
Cited by 12 | Viewed by 7671
Abstract
Temperature and relative humidity (RH) are two major external factors, which affect equilibrium moisture content (EMC) of wood-plastic composites (WPCs). In this study, the effect of different durability treatments on sorption and desorption isotherms of southern yellow pine (SYP)-high density polyethylene (HDPE) composites [...] Read more.
Temperature and relative humidity (RH) are two major external factors, which affect equilibrium moisture content (EMC) of wood-plastic composites (WPCs). In this study, the effect of different durability treatments on sorption and desorption isotherms of southern yellow pine (SYP)-high density polyethylene (HDPE) composites was investigated. All samples were equilibriumed at 20 °C and various RHs including 16%, 33%, 45%, 66%, 75%, 85%, 93%, and100%. EMCs obtained from desorption and absorption for different WPC samples were compared with Nelson’s sorption isotherm model predictions using the same temperature and humidity conditions. The results indicated that the amount of moisture absorbed increased with the increases in RH at 20 °C. All samples showed sorption hysteresis at a fixed RH. Small difference between EMC data of WPC samples containing different amount of ultraviolet (UV) stabilizers were observed. Similar results were observed among the samples containing different amount of zinc borate (ZB). The experimental data of EMCs at various RHs fit to the Nelson’s sorption isotherm model well. The Nelson’s model can be used to predicate EMCs of WPCs under different RH environmental conditions. Full article
(This article belongs to the Section Biomaterials)
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855 KiB  
Article
Photovoltaic and Impedance Spectroscopy Study of Screen-Printed TiO2 Based CdS Quantum Dot Sensitized Solar Cells
by M. Atif, W. A. Farooq, Amanullah Fatehmulla, M. Aslam and Syed Mansoor Ali
Materials 2015, 8(1), 355-367; https://doi.org/10.3390/ma8010355 - 19 Jan 2015
Cited by 24 | Viewed by 8146
Abstract
Cadmium sulphide (CdS) quantum dot sensitized solar cells (QDSSCs) based on screen-printed TiO2 were assembled using a screen-printing technique. The CdS quantum dots (QDs) were grown by using the Successive Ionic Layer Adsorption and Reaction (SILAR) method. The optical properties were studied [...] Read more.
Cadmium sulphide (CdS) quantum dot sensitized solar cells (QDSSCs) based on screen-printed TiO2 were assembled using a screen-printing technique. The CdS quantum dots (QDs) were grown by using the Successive Ionic Layer Adsorption and Reaction (SILAR) method. The optical properties were studied by UV-Vis absorbance spectroscopy. Photovoltaic characteristics and impedance spectroscopic measurements of CdS QDSSCs were carried out under air mass 1.5 illuminations. The experimental results of capacitance against voltage indicate a trend from positive to negative capacitance because of the injection of electrons from the Fluorine doped tin oxide (FTO) electrode into TiO2. Full article
(This article belongs to the Section Energy Materials)
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1039 KiB  
Article
Simple Response Surface Methodology: Investigation on Advance Photocatalytic Oxidation of 4-Chlorophenoxyacetic Acid Using UV-Active ZnO Photocatalyst
by Kian Mun Lee and Sharifah Bee Abd Hamid
Materials 2015, 8(1), 339-354; https://doi.org/10.3390/ma8010339 - 19 Jan 2015
Cited by 61 | Viewed by 6935
Abstract
The performance of advance photocatalytic degradation of 4-chlorophenoxyacetic acid (4-CPA) strongly depends on photocatalyst dosage, initial concentration and initial pH. In the present study, a simple response surface methodology (RSM) was applied to investigate the interaction between these three independent factors. Thus, the [...] Read more.
The performance of advance photocatalytic degradation of 4-chlorophenoxyacetic acid (4-CPA) strongly depends on photocatalyst dosage, initial concentration and initial pH. In the present study, a simple response surface methodology (RSM) was applied to investigate the interaction between these three independent factors. Thus, the photocatalytic degradation of 4-CPA in aqueous medium assisted by ultraviolet-active ZnO photocatalyst was systematically investigated. This study aims to determine the optimum processing parameters to maximize 4-CPA degradation. Based on the results obtained, it was found that a maximum of 91% of 4-CPA was successfully degraded under optimal conditions (0.02 g ZnO dosage, 20.00 mg/L of 4-CPA and pH 7.71). All the experimental data showed good agreement with the predicted results obtained from statistical analysis. Full article
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1628 KiB  
Article
Sulfadiazine—Chitosan Conjugates and Their Polyelectrolyte Complexes with Hyaluronate Destined to the Management of Burn Wounds
by Raluca Petronela Dumitriu, Lenuta Profire, Loredana Elena Nita, Oana Maria Dragostin, Nicolae Ghetu, Dragoș Pieptu and Cornelia Vasile
Materials 2015, 8(1), 317-338; https://doi.org/10.3390/ma8010317 - 16 Jan 2015
Cited by 18 | Viewed by 9375
Abstract
In the present study polyelectrolyte complexes (PECs) based on new sulfadiazine-chitosan conjugates with sodium hyaluronate have been developed with potential use in treatment of burn wounds. The PECs were chemically characterized using Fourier Transform—Infrared Spectroscopy, Scanning Electon Microscopy and Near Infrared Chemical Imaging [...] Read more.
In the present study polyelectrolyte complexes (PECs) based on new sulfadiazine-chitosan conjugates with sodium hyaluronate have been developed with potential use in treatment of burn wounds. The PECs were chemically characterized using Fourier Transform—Infrared Spectroscopy, Scanning Electon Microscopy and Near Infrared Chemical Imaging Technique. The swelling behavior and in vitro sulfadiazine release were also investigated. The antimicrobial activity was evaluated towards three bacterial strains: Escherichia coli, Listeria monocytogenes and Salmonella thyphymurium. The developed PECs demonstrated their antimicrobial efficiency against tested bacterial strains, the PECs containing sulfadiazine-modified chitosan being more active than PECs containing unmodified chitosan. Full article
(This article belongs to the Section Biomaterials)
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875 KiB  
Article
Evaluation of Biaxial Mechanical Properties of Aortic Media Based on the Lamellar Microstructure
by Hadi Taghizadeh, Mohammad Tafazzoli-Shadpour, Mohammad B. Shadmehr and Nasser Fatouraee
Materials 2015, 8(1), 302-316; https://doi.org/10.3390/ma8010302 - 16 Jan 2015
Cited by 21 | Viewed by 7491
Abstract
Evaluation of the mechanical properties of arterial wall components is necessary for establishing a precise mechanical model applicable in various physiological and pathological conditions, such as remodeling. In this contribution, a new approach for the evaluation of the mechanical properties of aortic media [...] Read more.
Evaluation of the mechanical properties of arterial wall components is necessary for establishing a precise mechanical model applicable in various physiological and pathological conditions, such as remodeling. In this contribution, a new approach for the evaluation of the mechanical properties of aortic media accounting for the lamellar structure is proposed. We assumed aortic media to be composed of two sets of concentric layers, namely sheets of elastin (Layer I) and interstitial layers composed of mostly collagen bundles, fine elastic fibers and smooth muscle cells (Layer II). Biaxial mechanical tests were carried out on human thoracic aortic samples, and histological staining was performed to distinguish wall lamellae for determining the dimensions of the layers. A neo-Hookean strain energy function (SEF) for Layer I and a four-parameter exponential SEF for Layer II were allocated. Nonlinear regression was used to find the material parameters of the proposed microstructural model based on experimental data. The non-linear behavior of media layers confirmed the higher contribution of elastic tissue in lower strains and the gradual engagement of collagen fibers. The resulting model determines the nonlinear anisotropic behavior of aortic media through the lamellar microstructure and can be assistive in the study of wall remodeling due to alterations in lamellar structure during pathological conditions and aging. Full article
(This article belongs to the Special Issue Mechanics of Biomaterials)
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8854 KiB  
Article
Characterization of the Microstructure Evolution in IF-Steel and AA6016 during Plane-Strain Tension and Simple Shear
by Gregory Gerstein, Benjamin Klusemann, Swantje Bargmann and Mirko Schaper
Materials 2015, 8(1), 285-301; https://doi.org/10.3390/ma8010285 - 15 Jan 2015
Cited by 3 | Viewed by 9366
Abstract
In the current work, the evolutions of grain and dislocation microstructures are investigated on the basis of plane strain tension and simple shear tests for an interstitial free steel (DC06) and a 6000 series aluminum alloy (AA6016-T4). Both materials are commonly-used materials in [...] Read more.
In the current work, the evolutions of grain and dislocation microstructures are investigated on the basis of plane strain tension and simple shear tests for an interstitial free steel (DC06) and a 6000 series aluminum alloy (AA6016-T4). Both materials are commonly-used materials in the automobile industry. The focus of this contribution is on the characterization and comparison of the microstructure formation in DC06 and AA6016-T4. Our observations shed light on the active mechanisms at the micro scale governing the macroscopic response. This knowledge is of great importance to understand the physical deformation mechanisms, allowing the control and design of new, tailor-made materials with the desired material behavior. Full article
(This article belongs to the Section Advanced Materials Characterization)
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912 KiB  
Article
Liquid Crystalline Esters of Dibenzophenazines
by Kevin John Anthony Bozek, Kuan I Ho, Tom Saint-Martin, Panos Argyropoulos and Vance E. Williams
Materials 2015, 8(1), 270-284; https://doi.org/10.3390/ma8010270 - 14 Jan 2015
Cited by 6 | Viewed by 6679
Abstract
A series of esters of 2,3,6,7-tetrakis(hexyloxy)dibenzo[a,c]phenazine-11-carboxylic acid was prepared in order to probe the effects of the ester groups on the liquid crystalline behavior. These compounds exhibit columnar hexagonal phases over broad temperature ranges. Variations in chain length, branching, [...] Read more.
A series of esters of 2,3,6,7-tetrakis(hexyloxy)dibenzo[a,c]phenazine-11-carboxylic acid was prepared in order to probe the effects of the ester groups on the liquid crystalline behavior. These compounds exhibit columnar hexagonal phases over broad temperature ranges. Variations in chain length, branching, terminal groups, and the presence of cyclic groups were found to modify transition temperatures without substantially destabilizing the mesophase range. Full article
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775 KiB  
Article
Comparative Study on Corrosion Protection of Reinforcing Steel by Using Amino Alcohol and Lithium Nitrite Inhibitors
by Han-Seung Lee, Hwa-Sung Ryu, Won-Jun Park and Mohamed A. Ismail
Materials 2015, 8(1), 251-269; https://doi.org/10.3390/ma8010251 - 14 Jan 2015
Cited by 50 | Viewed by 9136
Abstract
In this study, the ability of lithium nitrite and amino alcohol inhibitors to provide corrosion protection to reinforcing steel was investigated. Two types of specimens—reinforcing steel and a reinforced concrete prism that were exposed to chloride ion levels resembling the chloride attack environment—were [...] Read more.
In this study, the ability of lithium nitrite and amino alcohol inhibitors to provide corrosion protection to reinforcing steel was investigated. Two types of specimens—reinforcing steel and a reinforced concrete prism that were exposed to chloride ion levels resembling the chloride attack environment—were prepared. An autoclave accelerated corrosion test was then conducted. The variables tested included the chloride-ion concentration and molar ratios of anti-corrosion ingredients in a CaOH2-saturated aqueous solution that simulated a cement-pore solution. A concentration of 25% was used for the lithium nitrite inhibitor LiNO2, and an 80% solution of dimethyl ethanolamine ((CH3)2NCH2CH2OH, hereinafter DMEA) was used for the amino alcohol inhibitor. The test results indicated that the lithium nitrite inhibitor displayed anti-corrosion properties at a molar ratio of inhibitor of ≥0.6; the amino alcohol inhibitor also displayed anti-corrosion properties at molar ratios of inhibitor greater than approximately 0.3. Full article
(This article belongs to the Special Issue Corrosion of Materials)
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768 KiB  
Article
TiO2-Mediated Photocatalytic Mineralization of a Non-Ionic Detergent: Comparison and Combination with Other Advanced Oxidation Procedures
by Péter Hegedűs, Erzsébet Szabó-Bárdos, Ottó Horváth, Krisztián Horváth and Péter Hajós
Materials 2015, 8(1), 231-250; https://doi.org/10.3390/ma8010231 - 14 Jan 2015
Cited by 17 | Viewed by 8532
Abstract
Triton X-100 is one of the most widely-applied man-made non-ionic surfactants. This detergent can hardly be degraded by biological treatment. Hence, a more efficient degradation method is indispensable for the total mineralization of this pollutant. Application of heterogeneous photocatalysis based on a TiO [...] Read more.
Triton X-100 is one of the most widely-applied man-made non-ionic surfactants. This detergent can hardly be degraded by biological treatment. Hence, a more efficient degradation method is indispensable for the total mineralization of this pollutant. Application of heterogeneous photocatalysis based on a TiO2 suspension is a possible solution. Its efficiency may be improved by the addition of various reagents. We have thoroughly examined the photocatalytic degradation of Triton X-100 under various circumstances. For comparison, the efficiencies of ozonation and treatment with peroxydisulfate were also determined under the same conditions. Besides, the combination of these advanced oxidation procedures (AOPs) were also studied. The mineralization of this surfactant was monitored by following the TOC and pH values, as well as the absorption and emission spectra of the reaction mixture. An ultra-high-performance liquid chromatography (UHPLC) method was developed and optimized for monitoring the degradation of Triton X-100. Intermediates were also detected by GC-MS analysis and followed during the photocatalysis, contributing to the elucidation of the degradation mechanism. This non-ionic surfactant could be efficiently degraded by TiO2-mediated heterogeneous photocatalysis. However, surprisingly, its combination with the AOPs applied in this study did not enhance the rate of the mineralization. Moreover, the presence of persulfate hindered the photocatalytic degradation. Full article
(This article belongs to the Special Issue Photocatalytic Materials)
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1550 KiB  
Article
Cholesterol-Enhanced Polylactide-Based Stereocomplex Micelle for Effective Delivery of Doxorubicin
by Jixue Wang, Weiguo Xu, Jianxun Ding, Shengfan Lu, Xiaoqing Wang, Chunxi Wang and Xuesi Chen
Materials 2015, 8(1), 216-230; https://doi.org/10.3390/ma8010216 - 12 Jan 2015
Cited by 28 | Viewed by 9367
Abstract
Nanoscale micelles as an effective drug delivery system have attracted increasing interest in malignancy therapy. The present study reported the construction of the cholesterol-enhanced doxorubicin (DOX)-loaded poly(D-lactide)-based micelle (CDM/DOX), poly(L-lactide)-based micelle (CLM/DOX), and stereocomplex micelle (CSCM/DOX) from the equimolar enantiomeric 4-armed poly(ethylene glycol)–polylactide [...] Read more.
Nanoscale micelles as an effective drug delivery system have attracted increasing interest in malignancy therapy. The present study reported the construction of the cholesterol-enhanced doxorubicin (DOX)-loaded poly(D-lactide)-based micelle (CDM/DOX), poly(L-lactide)-based micelle (CLM/DOX), and stereocomplex micelle (CSCM/DOX) from the equimolar enantiomeric 4-armed poly(ethylene glycol)–polylactide copolymers in aqueous condition. Compared with CDM/DOX and CLM/DOX, CSCM/DOX showed the smallest hydrodynamic size of 96 ± 4.8 nm and the slowest DOX release. The DOX-loaded micelles exhibited a weaker DOX fluorescence inside mouse renal carcinoma cells (i.e., RenCa cells) compared to free DOX·HCl, probably because of a slower DOX release. More importantly, all the DOX-loaded micelles, especially CSCM/DOX, exhibited the excellent antiproliferative efficacy that was equal to or even better than free DOX·HCl toward RenCa cells attributed to their successful internalization. Furthermore, all of the DOX-loaded micelles exhibited the satisfactory hemocompatibility compared to free DOX·HCl, indicating the great potential for systemic chemotherapy through intravenous injection. Full article
(This article belongs to the Special Issue Materials for Drug Delivery)
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667 KiB  
Article
Nanoindentation and XPS Studies of Titanium TNZ Alloy after Electrochemical Polishing in a Magnetic Field
by Tadeusz Hryniewicz, Krzysztof Rokosz, Ryszard Rokicki and Frédéric Prima
Materials 2015, 8(1), 205-215; https://doi.org/10.3390/ma8010205 - 8 Jan 2015
Cited by 39 | Viewed by 7356
Abstract
This work presents the nanoindentation and XPS results of a newly-developed biomaterial of titanium TNZ alloy after different surface treatments. The investigations were performed on the samples AR (as received), EP (after a standard electropolishing) and MEP (after magnetoelectropolishing). The electropolishing processes, both [...] Read more.
This work presents the nanoindentation and XPS results of a newly-developed biomaterial of titanium TNZ alloy after different surface treatments. The investigations were performed on the samples AR (as received), EP (after a standard electropolishing) and MEP (after magnetoelectropolishing). The electropolishing processes, both EP and MEP, were conducted in the same proprietary electrolyte based on concentrated sulfuric acid. The mechanical properties of the titanium TNZ alloy biomaterial demonstrated an evident dependence on the surface treatment method, with MEP samples revealing extremely different behavior and mechanical properties. The reason for that different behavior appeared to be influenced by the surface film composition, as revealed by XPS study results displayed in this work. The increase of niobium and zirconium in the surface film of the same titanium TNZ alloy after magnetoelectropolishing MEP treatment is meaningful and especially advantageous considering the application of this alloy as a biomaterial. Full article
(This article belongs to the Section Biomaterials)
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175 KiB  
Editorial
Acknowledgement to Reviewers of Materials in 2014
by Materials Editorial Office
Materials 2015, 8(1), 193-204; https://doi.org/10.3390/ma8010193 - 7 Jan 2015
Viewed by 4648
Abstract
The editors of Materials would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...] Full article
1487 KiB  
Article
Fabrication and Assessment of Crumb-Rubber-Modified Coatings with Anticorrosive Properties
by Nasser Al-Aqeeli
Materials 2015, 8(1), 181-192; https://doi.org/10.3390/ma8010181 - 6 Jan 2015
Cited by 12 | Viewed by 5770
Abstract
Scrap tires continue to be a major source of waste due to the lack of valuable and effective disposal routes. A viable solution to this problem is to recycle crumb rubber (CR)—a granulated material derived from scrap tires—and use it to develop other [...] Read more.
Scrap tires continue to be a major source of waste due to the lack of valuable and effective disposal routes. A viable solution to this problem is to recycle crumb rubber (CR)—a granulated material derived from scrap tires—and use it to develop other valuable products. Herein we report the fabrication and characterization of CR-modified coatings with anticorrosive properties on metal substrates. By varying the particle size and concentration of CR, we have determined the coating composition that offers the highest level of erosion protection. Images from a scanning electron microscope (SEM) reveal that CR is homogenously dispersed in the coating, especially when fine particles are used. As the concentration of CR increases, the hardness of the coating decreases as a result of the elastic properties of CR. More importantly, the erosion rate of the coating decreases due to increased ductility. Following Potentiodynamic tests, the utilization of these coatings proved to be beneficial as they showed good protection against aqueous corrosion when tested in 0.5 M NaCl solution. Our newly developed coatings offer an incentive to recycling CR and open up a safe and sustainable route to the disposal of scrap tires. Full article
(This article belongs to the Section Manufacturing Processes and Systems)
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3809 KiB  
Article
Differently Shaped Au Nanoparticles: A Case Study on the Enhancement of the Photocatalytic Activity of Commercial TiO2
by Zsolt Pap, Zsejke Réka Tóth, Virginia Danciu, Lucian Baia and Gábor Kovács
Materials 2015, 8(1), 162-180; https://doi.org/10.3390/ma8010162 - 31 Dec 2014
Cited by 14 | Viewed by 7949
Abstract
In the present work, the influence of a gold nanoparticle’s shape was investigated on the commercially available Evonik Aeroxide P25. By the variation of specific synthesis parameters, three differently shaped Au nanoparticles were synthetized and deposited on the surface of the chosen commercial [...] Read more.
In the present work, the influence of a gold nanoparticle’s shape was investigated on the commercially available Evonik Aeroxide P25. By the variation of specific synthesis parameters, three differently shaped Au nanoparticles were synthetized and deposited on the surface of the chosen commercial titania. The nanoparticles and their composites’ morphological and structural details were evaluated, applying different techniques such as Diffuse Reflectance Spectroscopy (DRS), X-ray Diffraction (XRD), and Transmission Electron Microscopy (TEM). The influence of the Au nanoparticles’ shape was discussed by evaluating their photocatalytic efficiency on phenol and oxalic acid degradation and by investigating the H2 production efficacy of the selected composites. Major differences in their photocatalytic performance depending on the shape of the deposited noble metal were evidenced. Full article
(This article belongs to the Special Issue Photocatalytic Materials)
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1422 KiB  
Article
Synthesis of Co3O4 Cotton-Like Nanostructures for Cholesterol Biosensor
by Sami Elhag, Zafar Hussain Ibupoto, Omer Nour and Magnus Willander
Materials 2015, 8(1), 149-161; https://doi.org/10.3390/ma8010149 - 31 Dec 2014
Cited by 23 | Viewed by 7789
Abstract
The use of templates to assist and possess a control over the synthesis of nanomaterials has been an attractive option to achieve this goal. Here we have used sodium dodecyl sulfate (SDS) to act as a template for the low temperature synthesis of [...] Read more.
The use of templates to assist and possess a control over the synthesis of nanomaterials has been an attractive option to achieve this goal. Here we have used sodium dodecyl sulfate (SDS) to act as a template for the low temperature synthesis of cobalt oxide (Co3O4) nanostructures. The use of SDS has led to tune the morphology, and the product was in the form of “cotton-like” nanostructures instead of connected nanowires. Moreover, the variation of the amount of the SDS used was found to affect the charge transfer process in the Co3O4. Using Co3O4 synthesized using the SDS for sensing of cholesterol was investigated. The use of the Co3O4 synthesized using the SDS was found to yield an improved cholesterol biosensor compared to Co3O4 synthesized without the SDS. The improvement of the cholesterol sensing properties upon using the SDS as a template was manifested in increasing the sensitivity and the dynamic range of detection. The results achieved in this study indicate the potential of using template assisted synthesis of nanomaterials in improving some properties, e.g., cholesterol sensing. Full article
(This article belongs to the Section Advanced Materials Characterization)
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681 KiB  
Article
Preparation and Characterization of Films Extruded of Polyethylene/Chitosan Modified with Poly(lactic acid)
by Jesús Manuel Quiroz-Castillo, Dora Evelia Rodríguez-Félix, Heriberto Grijalva-Monteverde, Lauren Lucero Lizárraga-Laborín, María Mónica Castillo-Ortega, Teresa Del Castillo-Castro, Francisco Rodríguez-Félix and Pedro Jesús Herrera-Franco
Materials 2015, 8(1), 137-148; https://doi.org/10.3390/ma8010137 - 30 Dec 2014
Cited by 26 | Viewed by 8244
Abstract
The use of mixtures of synthetic and natural polymers is a potential option to reduce the pollution by plastic waste. In this work, the method for the chemical modification of chitosan with poly(lactic acid) was developed; then, the preparation of films of blends [...] Read more.
The use of mixtures of synthetic and natural polymers is a potential option to reduce the pollution by plastic waste. In this work, the method for the chemical modification of chitosan with poly(lactic acid) was developed; then, the preparation of films of blends of polyethylene and chitosan-poly(lactic acid) produced by an extrusion method using polyethylene-graft maleic anhydride as a compatibilizer. It was possible to obtain films with a maximum content of 20 wt% and 30 wt%, chitosan, with and without compatibilizer, respectively. Scanning electron microscope (SEM) analysis showed a homogeneous surface on all films. The addition of the compatibilizer had a significant effect on the mechanical properties of the films, such as an increase in Young’s modulus and a decrease in the elongation at break; additionally, the compatibilizer promotes thermal degradation in a single step and gives the film a slight increase in thermal resistance. These results are attributed to an improved interaction in the interface of polyethylene and chitosan-poly(lactic acid), promoted by the compatibilizer. Full article
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536 KiB  
Article
The Bi-Directional Prediction of Carbon Fiber Production Using a Combination of Improved Particle Swarm Optimization and Support Vector Machine
by Chuncai Xiao, Kuangrong Hao and Yongsheng Ding
Materials 2015, 8(1), 117-136; https://doi.org/10.3390/ma8010117 - 30 Dec 2014
Cited by 13 | Viewed by 6929
Abstract
This paper creates a bi-directional prediction model to predict the performance of carbon fiber and the productive parameters based on a support vector machine (SVM) and improved particle swarm optimization (IPSO) algorithm (SVM-IPSO). In the SVM, it is crucial to select the parameters [...] Read more.
This paper creates a bi-directional prediction model to predict the performance of carbon fiber and the productive parameters based on a support vector machine (SVM) and improved particle swarm optimization (IPSO) algorithm (SVM-IPSO). In the SVM, it is crucial to select the parameters that have an important impact on the performance of prediction. The IPSO is proposed to optimize them, and then the SVM-IPSO model is applied to the bi-directional prediction of carbon fiber production. The predictive accuracy of SVM is mainly dependent on its parameters, and IPSO is thus exploited to seek the optimal parameters for SVM in order to improve its prediction capability. Inspired by a cell communication mechanism, we propose IPSO by incorporating information of the global best solution into the search strategy to improve exploitation, and we employ IPSO to establish the bi-directional prediction model: in the direction of the forward prediction, we consider productive parameters as input and property indexes as output; in the direction of the backward prediction, we consider property indexes as input and productive parameters as output, and in this case, the model becomes a scheme design for novel style carbon fibers. The results from a set of the experimental data show that the proposed model can outperform the radial basis function neural network (RNN), the basic particle swarm optimization (PSO) method and the hybrid approach of genetic algorithm and improved particle swarm optimization (GA-IPSO) method in most of the experiments. In other words, simulation results demonstrate the effectiveness and advantages of the SVM-IPSO model in dealing with the problem of forecasting. Full article
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832 KiB  
Article
Adsorption of C.I. Natural Red 4 onto Spongin Skeleton of Marine Demosponge
by Małgorzata Norman, Przemysław Bartczak, Jakub Zdarta, Włodzimierz Tylus, Tomasz Szatkowski, Allison L. Stelling, Hermann Ehrlich and Teofil Jesionowski
Materials 2015, 8(1), 96-116; https://doi.org/10.3390/ma8010096 - 29 Dec 2014
Cited by 38 | Viewed by 8747
Abstract
C.I. Natural Red 4 dye, also known as carmine or cochineal, was adsorbed onto the surface of spongin-based fibrous skeleton of Hippospongia communis marine demosponge for the first time. The influence of the initial concentration of dye, the contact time, and the pH [...] Read more.
C.I. Natural Red 4 dye, also known as carmine or cochineal, was adsorbed onto the surface of spongin-based fibrous skeleton of Hippospongia communis marine demosponge for the first time. The influence of the initial concentration of dye, the contact time, and the pH of the solution on the adsorption process was investigated. The results presented here confirm the effectiveness of the proposed method for developing a novel dye/biopolymer hybrid material. The kinetics of the adsorption of carmine onto a marine sponge were also determined. The experimental data correspond directly to a pseudo-second-order model for adsorption kinetics (r2 = 0.979–0.999). The hybrid product was subjected to various types of analysis (FT-IR, Raman, 13C CP/MAS NMR, XPS) to investigate the nature of the interactions between the spongin (adsorbent) and the dye (the adsorbate). The dominant interactions between the dye and spongin were found to be hydrogen bonds and electrostatic effects. Combining the dye with a spongin support resulted with a novel hybrid material that is potentially attractive for bioactive applications and drug delivery systems. Full article
(This article belongs to the Special Issue Advances in Colorants 2014)
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940 KiB  
Review
Water-Assisted Production of Thermoplastic Nanocomposites: A Review
by József Karger-Kocsis, Ákos Kmetty, László Lendvai, Stavros X. Drakopoulos and Tamás Bárány
Materials 2015, 8(1), 72-95; https://doi.org/10.3390/ma8010072 - 29 Dec 2014
Cited by 61 | Viewed by 11482
Abstract
Water-assisted, or more generally liquid-mediated, melt compounding of nanocomposites is basically a combination of solution-assisted and traditional melt mixing methods. It is an emerging technique to overcome several disadvantages of the above two. Water or aqueous liquids with additives, do not work merely [...] Read more.
Water-assisted, or more generally liquid-mediated, melt compounding of nanocomposites is basically a combination of solution-assisted and traditional melt mixing methods. It is an emerging technique to overcome several disadvantages of the above two. Water or aqueous liquids with additives, do not work merely as temporary carrier materials of suitable nanofillers. During batchwise and continuous compounding, these liquids are fully or partly evaporated. In the latter case, the residual liquid is working as a plasticizer. This processing technique contributes to a better dispersion of the nanofillers and affects markedly the morphology and properties of the resulting nanocomposites. A survey is given below on the present praxis and possible future developments of water-assisted melt mixing techniques for the production of thermoplastic nanocomposites. Full article
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994 KiB  
Article
A New Wide-Band Double-Negative Metamaterial for C- and S-Band Applications
by Md Ikbal Hossain, Mohammad Rashed Iqbal Faruque, Mohammad Tariqul Islam and Mohammad Habib Ullah
Materials 2015, 8(1), 57-71; https://doi.org/10.3390/ma8010057 - 25 Dec 2014
Cited by 60 | Viewed by 8966
Abstract
A new design and analysis of a wide-band double-negative metamaterial, considering a frequency range of 0.5 to 7 GHz, is presented in this paper. Four different unit cells with varying design parameters are analyzed to evaluate the effects of the unit-cell size on [...] Read more.
A new design and analysis of a wide-band double-negative metamaterial, considering a frequency range of 0.5 to 7 GHz, is presented in this paper. Four different unit cells with varying design parameters are analyzed to evaluate the effects of the unit-cell size on the resonance frequencies of the metamaterial. Moreover, open and interconnected 2 × 2 array structures of unit cells are analyzed. The finite-difference time-domain (FDTD) method, based on the Computer Simulation Technology (CST) Microwave Studio, is utilized in the majority of this investigation. The experimental portion of the study was performed in a semi-anechoic chamber. Good agreement is observed between the simulated and measured S parameters of the developed unit cell and array. The designed unit cell exhibits negative permittivity and permeability simultaneously at S-band (2.95 GHz to 4.00 GHz) microwave frequencies. In addition, the designed unit cell can also operate as a double-negative medium throughout the C band (4.00 GHz to 4.95 GHz and 5.00 GHz to 5.57 GHz). At a number of other frequencies, it exhibits a single negative value. The two array configurations cause a slight shift in the resonance frequencies of the metamaterial and hence lead to a slight shift of the single- and double-negative frequency ranges of the metamaterial. Full article
(This article belongs to the Section Advanced Materials Characterization)
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1589 KiB  
Article
Fullerene-Based Photoactive Layers for Heterojunction Solar Cells: Structure, Absorption Spectra and Charge Transfer Process
by Yuanzuo Li, Dawei Qi, Peng Song and Fengcai Ma
Materials 2015, 8(1), 42-56; https://doi.org/10.3390/ma8010042 - 25 Dec 2014
Cited by 41 | Viewed by 8206
Abstract
The electronic structure and optical absorption spectra of polymer APFO3, [70]PCBM/APFO3 and [60]PCBM/APFO3, were studied with density functional theory (DFT), and the vertical excitation energies were calculated within the framework of the time-dependent DFT (TD-DFT). Visualized charge difference [...] Read more.
The electronic structure and optical absorption spectra of polymer APFO3, [70]PCBM/APFO3 and [60]PCBM/APFO3, were studied with density functional theory (DFT), and the vertical excitation energies were calculated within the framework of the time-dependent DFT (TD-DFT). Visualized charge difference density analysis can be used to label the charge density redistribution for individual fullerene and fullerene/polymer complexes. The results of current work indicate that there is a difference between [60]PCBM and [70]PCBM, and a new charge transfer process is observed. Meanwhile, for the fullerene/polymer complex, all calculations of the twenty excited states were analyzed to reveal all possible charge transfer processes in depth. We also estimated the electronic coupling matrix, reorganization and Gibbs free energy to further calculate the rates of the charge transfer and the recombination. Our results give a clear picture of the structure, absorption spectra, charge transfer (CT) process and its influencing factors, and provide a theoretical guideline for designing further photoactive layers of solar cells. Full article
(This article belongs to the Section Energy Materials)
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1260 KiB  
Article
Enhanced Photocatalytic Efficiency of N–F-Co-Embedded Titania under Visible Light Exposure for Removal of Indoor-Level Pollutants
by Seung-Ho Shin, Ho-Hwan Chun and Wan-Kuen Jo
Materials 2015, 8(1), 31-41; https://doi.org/10.3390/ma8010031 - 24 Dec 2014
Cited by 9 | Viewed by 5861
Abstract
N–F-co-embedded titania (N–F–TiO2) photocatalysts with varying N:F ratios were synthesized and tested for their ability to photocatalyze the degradation of pollutants present at indoor air levels using visible light. The synthesis was achieved using a solvothermal process with tetrabutyl titanate, urea [...] Read more.
N–F-co-embedded titania (N–F–TiO2) photocatalysts with varying N:F ratios were synthesized and tested for their ability to photocatalyze the degradation of pollutants present at indoor air levels using visible light. The synthesis was achieved using a solvothermal process with tetrabutyl titanate, urea and ammonium fluoride as sources of Ti, N and F, respectively. Three selected volatile organic compounds (toluene, ethyl benzene and o-xylene) were selected as the test pollutants. The prepared composites were characterized using X-ray diffraction, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and Ultra-violet (UV)-visible spectroscopy. The photocatalytic degradation efficiencies of N–F–TiO2 composites were higher than those obtained using pure TiO2 and N–TiO2. Moreover, these efficiencies increased as the N:F ratio decreased from sixteen to eight, then decreased as it dropped further to three, indicating the presence of an optimal N:F ratio. Meanwhile, as retention time decreased from 12.4 to 0.62 s, the average photocatalytic efficiencies decreased from 65.4% to 21.7%, 91.5% to 37.8% and 95.8% to 44.7% for toluene, ethyl benzene and o-xylene, respectively. In contrast, the photocatalytic reaction rates increased as retention time decreased. In consideration of all of these factors, under optimized operational conditions, the prepared N–F–TiO2 composites could be utilized for the degradation of target pollutants at indoor air levels using visible light. Full article
(This article belongs to the Special Issue Photocatalytic Materials)
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558 KiB  
Article
Photocatalytic Water Splitting for Hydrogen Production with Gd2MSbO7 (M = Fe, In, Y) Photocatalysts under Visible Light Irradiation
by Jingfei Luan and Yanyan Li
Materials 2015, 8(1), 16-30; https://doi.org/10.3390/ma8010016 - 24 Dec 2014
Cited by 11 | Viewed by 6692
Abstract
Novel photocatalysts Gd2FeSbO7, Gd2InSbO7 and Gd2YSbO7 were synthesized by the solid state reaction method for the first time. A comparative study about the structural and photocatalytic properties of Gd2MSbO7 (M [...] Read more.
Novel photocatalysts Gd2FeSbO7, Gd2InSbO7 and Gd2YSbO7 were synthesized by the solid state reaction method for the first time. A comparative study about the structural and photocatalytic properties of Gd2MSbO7 (M = Fe, In, Y) was reported. The results showed that Gd2FeSbO7, Gd2InSbO7 and Gd2YSbO7 crystallized with the pyrochlore-type structure, cubic crystal system and space group Fd3m. The lattice parameter a for Gd2FeSbO7, Gd2InSbO7 or Gd2YSbO7 was 10.276026 Å, 10.449546 Å or 10.653651 Å. The band gap of Gd2FeSbO7, Gd2InSbO7 or Gd2YSbO7 was estimated to be 2.151 eV, 2.897 eV or 2.396 eV. For the photocatalytic water-splitting reaction, H2 or O2 evolution was observed from pure water with Gd2FeSbO7, Gd2InSbO7 or Gd2YSbO7 as catalyst under visible light irradiation (wavelength > 420 nm). Moreover, H2 or O2 also spilt by using Gd2FeSbO7, Gd2InSbO7 or Gd2YSbO7 as catalyst from CH3OH/H2O or AgNO3/H2O solutions under visible light irradiation (λ > 420 nm). Gd2FeSbO7 showed the highest activity compared with Gd2InSbO7 or Gd2YSbO7. At the same time, Gd2InSbO7 showed higher activity compared with Gd2YSbO7. The photocatalytic activities were further improved under visible light irradiation with Gd2FeSbO7, Gd2InSbO7 or Gd2YSbO7 being loaded by Pt, NiO or RuO2. The effect of Pt was better than that of NiO or RuO2 for improving the photocatalytic activity of Gd2FeSbO7, Gd2InSbO7 or Gd2YSbO7. Full article
(This article belongs to the Special Issue Photocatalytic Materials)
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519 KiB  
Communication
First Exploratory Study on the Ageing of Rammed Earth Material
by Quoc-Bao Bui and Jean-Claude Morel
Materials 2015, 8(1), 1-15; https://doi.org/10.3390/ma8010001 - 23 Dec 2014
Cited by 20 | Viewed by 7222
Abstract
Rammed earth (RE) is attracting renewed interest throughout the world thanks to its “green” characteristics in the context of sustainable building. In this study, the ageing effects on RE material are studied on the walls which have been constructed and exposed for 22 [...] Read more.
Rammed earth (RE) is attracting renewed interest throughout the world thanks to its “green” characteristics in the context of sustainable building. In this study, the ageing effects on RE material are studied on the walls which have been constructed and exposed for 22 years to natural weathering. First, mechanical characteristics of the “old” walls were determined by two approaches: in-situ dynamic measurements on the walls; laboratory tests on specimens which had been cut from the walls. Then, the walls’ soil was recycled and reused for manufacturing of new specimens which represented the initial state. Comparison between the compressive strength, the Young modulus of the walls after 22 years on site and that of the initial state enables to assess the ageing of the studied walls. Full article
(This article belongs to the Section Advanced Materials Characterization)
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