Materials

9599 KiB

Open AccessArticle

Effects of BMP-2 Delivery in Calcium Phosphate Bone Graft Materials with Different Compositions on Bone Regeneration

by Jin-Chul Park, Eun-Bin Bae, Se-Eun Kim, So-Yun Kim, Kyung-Hee Choi, Jae-Won Choi, Ji-Hyeon Bae, Jae-Jun Ryu and Jung-Bo Huh

Materials 2016, 9(11), 954; https://doi.org/10.3390/ma9110954 - 23 Nov 2016

Cited by 10 | Viewed by 5462

Abstract

This study was undertaken to investigate the effect of loading rhBMP-2 onto biphasic calcium phosphate (BCP) and calcium pyrophosphate (CPP) on bone regeneration, and to examine the efficacies of BCP and CPP as rhBMP-2 carriers. Specimens were divided into the BCP, CPP, BCP/BMP, [...] Read more.

This study was undertaken to investigate the effect of loading rhBMP-2 onto biphasic calcium phosphate (BCP) and calcium pyrophosphate (CPP) on bone regeneration, and to examine the efficacies of BCP and CPP as rhBMP-2 carriers. Specimens were divided into the BCP, CPP, BCP/BMP, and CPP/BMP groups; BCP and CPP were in granules and not coated with rhBMP-2. BCP/BMP and CPP/BMP were prepared as discs, which were treated with rhBMP-2 and collagen. Physical and biological features were investigated using in-vitro and in-vivo tests. New bone area percentages (%) in the BCP/BMP and CPP/BMP groups were significantly greater than in the BCP and CPP groups. At weeks 4 and 8 post-implantation, CPP/BMP showed the most new bone growth. Within the limitations of this study, treatment of BCP and CPP with rhBMP-2 significantly enhanced bone regeneration. CPP was found to be a suitable carrier for rhBMP-2. Full article

(This article belongs to the Section Biomaterials)

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2108 KiB

Open AccessArticle

Recording Characteristics, Microstructure, and Crystallization Kinetics of Ge/GeCu Recording Film Used for Write-Once Blu-Ray Disc

by Sin-Liang Ou, Feng-Min Lai, Wei-Kai Wang, Shih-Yung Huang, An-Cheng Sun, Ching-Ho Tien, Zhi-Jia Xu, Chin-Yen Yeh and Kuo-Sheng Kao

Materials 2016, 9(11), 953; https://doi.org/10.3390/ma9110953 - 23 Nov 2016

Viewed by 4192

Abstract

A Ge₆₇Cu₃₃ (16 nm) layer and a Ge (3 nm)/Ge₆₇Cu₃₃ (16 nm) bilayer were grown by sputtering at room temperature and used as the recording films for write-once blue laser media. In comparison to the crystallization temperature [...] Read more.

A Ge₆₇Cu₃₃ (16 nm) layer and a Ge (3 nm)/Ge₆₇Cu₃₃ (16 nm) bilayer were grown by sputtering at room temperature and used as the recording films for write-once blue laser media. In comparison to the crystallization temperature of Ge in a GeCu film (380.7 °C–405.1 °C), the crystallization temperature of Ge in a Ge/GeCu bilayer could be further decreased to 333.7 °C–382.8 °C. The activation energies of Ge crystallization were 3.51 eV ± 0.05 eV and 1.50 eV ± 0.04 eV for the GeCu and the Ge/GeCu films, respectively, indicating that the Ge/GeCu bilayer possesses a higher feasibility in high-speed optical recording applications. Moreover, the lower activation energy would lead to a larger grain size of Ge crystallization in the Ge/GeCu bilayer after the annealing process. Between the as-deposited and the annealed states, the optical contrasts (@ 405 nm) of the GeCu and the Ge/GeCu films were 26.0% and 47.5%, respectively. This reveals that the Ge/GeCu bilayer is more suitable for the recording film of a write-once blu-ray disc (BD-R) in comparison with the GeCu film. Based on the dynamic tests performed for 2× and 4× recording speeds, the optimum jitter values of the BD-R with the Ge/GeCu recording film were 7.4% at 6.3 mW and 7.6% at 8.6 mW, respectively. Full article

(This article belongs to the Special Issue Selected Papers from IS3C2016)

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4296 KiB

Open AccessArticle

The Effect of Curing Temperature on the Properties of Cement Pastes Modified with TiO₂ Nanoparticles

by Karine Pimenta Teixeira, Isadora Perdigão Rocha, Leticia De Sá Carneiro, Jessica Flores, Edward A. Dauer and Ali Ghahremaninezhad

Materials 2016, 9(11), 952; https://doi.org/10.3390/ma9110952 - 23 Nov 2016

Cited by 42 | Viewed by 6444

Abstract

This paper investigates the effect of curing temperature on the hydration, microstructure, compressive strength, and transport of cement pastes modified with TiO₂ nanoparticles. These characteristics of cement pastes were studied using non-evaporable water content measurement, X-ray diffraction (XRD), compressive strength test, electrical [...] Read more.

This paper investigates the effect of curing temperature on the hydration, microstructure, compressive strength, and transport of cement pastes modified with TiO₂ nanoparticles. These characteristics of cement pastes were studied using non-evaporable water content measurement, X-ray diffraction (XRD), compressive strength test, electrical resistivity and porosity measurements, and scanning electron microscopy (SEM). It was shown that temperature enhanced the early hydration. The cement pastes cured at elevated temperatures generally showed an increase in compressive strength at an early age compared to the cement paste cured at room temperature, but the strength gain decreased at later ages. The electrical resistivity of the cement pastes cured at elevated temperatures was found to decrease more noticeably at late ages compared to that of the room temperature cured cement paste. SEM examination indicated that hydration product was more uniformly distributed in the microstructure of the cement paste cured at room temperature compared to the cement pastes cured at elevated temperatures. It was observed that high temperature curing decreased the compressive strength and electrical resistivity of the cement pastes at late ages in a more pronounced manner when higher levels of TiO₂ nanoparticles were added. Full article

(This article belongs to the Section Advanced Materials Characterization)

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Open AccessArticle

Fabrication of Al/Mg/Al Composites via Accumulative Roll Bonding and Their Mechanical Properties

by Jinfeng Nie, Mingxing Liu, Fang Wang, Yonghao Zhao, Yusheng Li, Yang Cao and Yuntian Zhu

Materials 2016, 9(11), 951; https://doi.org/10.3390/ma9110951 - 23 Nov 2016

Cited by 51 | Viewed by 6073

Abstract

Al(1060)/Mg(AZ31)/Al(1060) multilayered composite was successfully produced using an accumulative roll bonding (ARB) process for up to four cycles at an elevated temperature (400 °C). The microstructure evolution of the composites and the bonding characteristics at the interfaces between Al and Mg layers with [...] Read more.

Al(1060)/Mg(AZ31)/Al(1060) multilayered composite was successfully produced using an accumulative roll bonding (ARB) process for up to four cycles at an elevated temperature (400 °C). The microstructure evolution of the composites and the bonding characteristics at the interfaces between Al and Mg layers with increasing ARB cycles were characterized through optical microscopy, field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). It was found that the grains of Al and Mg layers were significantly refined and Al₃Mg₂ and Al₁₂ Mg₁₇ intermetallic compound layers formed at the Al/Mg bonding interfaces. The strength increased gradually and the ultimate tensile strength (UTS) reached a maximum value of about 240 MPa at the third pass. Furthermore, the strengthening mechanism of the composite was analyzed based on the fracture morphologies. Full article

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5936 KiB

Open AccessArticle

Friction and Wear Reduction of Eccentric Journal Bearing Made of Sn-Based Babbitt for Ore Cone Crusher

by Auezhan Amanov, Byungmin Ahn, Moon Gu Lee, Yongho Jeon and Young-Sik Pyun

Materials 2016, 9(11), 950; https://doi.org/10.3390/ma9110950 - 22 Nov 2016

Cited by 17 | Viewed by 8008

Abstract

An anti-friction Babbitt alloy-coated bearing made by a casting process is a journal bearing, which is used in an ore cone crusher eccentric. The main purpose of the Babbitt coated eccentric is to provide a low friction to support and guide a rotating [...] Read more.

An anti-friction Babbitt alloy-coated bearing made by a casting process is a journal bearing, which is used in an ore cone crusher eccentric. The main purpose of the Babbitt coated eccentric is to provide a low friction to support and guide a rotating shaft. Despite the fact that the Babbitt-coated eccentric offers a low friction coefficient and can be operated without a continuous supply of lubricant, it suffers from mining environments and short service life. In this study, an ultrasonic nanocrystalline surface modification (UNSM) technique was used to further reduce the friction coefficient, to increase the wear resistance, and to extend the service life of the Sn-based Babbitt metal. The friction and wear behavior of the Sn-based Babbitt metal was investigated using a block-on-ring tester under both dry and oil-lubricated conditions. The results of the experiments revealed that the friction and wear behavior of Sn-based Babbitt metal could be improved by the application of the UNSM technique. The friction and wear mechanisms of the specimens were explained and discussed in terms of changes in surface properties—microstructure, surface hardness, surface roughness, etc. Full article

(This article belongs to the Special Issue Tribological Behavior of Materials by Surface Engineering)

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16565 KiB

Open AccessArticle

In Vitro and In Vivo Study of a Novel Porcine Collagen Membrane for Guided Bone Regeneration

by Eisner Salamanca, Chi-Yang Tsai, Yu-Hwa Pan, Yu-Te Lin, Haw-Ming Huang, Nai-Chia Teng, Che-Tong Lin, Sheng-Wei Feng and Wei-Jen Chang

Materials 2016, 9(11), 949; https://doi.org/10.3390/ma9110949 - 22 Nov 2016

Cited by 18 | Viewed by 6601

Abstract

For years, in order to improve bone regeneration and prevent the need of a second stage surgery to remove non-resorbable membranes, biological absorbable membranes have gradually been developed and applied in guided tissue regeneration (GTR). The present study’s main objective was to achieve [...] Read more.

For years, in order to improve bone regeneration and prevent the need of a second stage surgery to remove non-resorbable membranes, biological absorbable membranes have gradually been developed and applied in guided tissue regeneration (GTR). The present study’s main objective was to achieve space maintenance and bone regeneration using a new freeze-dried developed porcine collagen membrane, and compare it with an already commercial collagen membrane, when both were used with a bovine xenograft in prepared alveolar ridge bone defects. Prior to surgery, the membrane’s vitality analysis showed statistically significant higher cell proliferation in the test membrane over the commercial one. In six beagle dogs, commercial bone xenograft was packed in lateral ridge bone defects prepared in the left and right side and then covered with test porcine collagen membrane or commercial collagen membrane. Alveolar height changes were measured. Histomorphometric results, in vitro and in vivo properties indicated that the new porcine collagen membrane is biocompatible, enhances bone xenograft osteoconduction, and reduces the alveolar ridge height reabsorption rate. Full article

(This article belongs to the Special Issue Materials for Hard and Soft Tissue Engineering: Novel Approaches)

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2533 KiB

Open AccessArticle

Prediction of Three-Dimensional Downward Flame Spread Characteristics over Poly(methyl methacrylate) Slabs in Different Pressure Environments

by Kun Zhao, Xiao-Dong Zhou, Xue-Qiang Liu, Lei Lu, Zhi-Bo Wu, Fei Peng, Xiao-Yu Ju and Li-Zhong Yang

Materials 2016, 9(11), 948; https://doi.org/10.3390/ma9110948 - 22 Nov 2016

Cited by 15 | Viewed by 4795

Abstract

The present study is aimed at predicting downward flame spread characteristics over poly(methyl methacrylate) (PMMA) with different sample dimensions in different pressure environments. Three-dimensional (3-D) downward flame spread experiments on free PMMA slabs were conducted at five locations with different altitudes, which provide [...] Read more.

The present study is aimed at predicting downward flame spread characteristics over poly(methyl methacrylate) (PMMA) with different sample dimensions in different pressure environments. Three-dimensional (3-D) downward flame spread experiments on free PMMA slabs were conducted at five locations with different altitudes, which provide different pressures. Pressure effects on the flame spread rate, profile of pyrolysis front and flame height were analyzed at all altitudes. The flame spread rate in the steady-state stage was calculated based on the balance on the fuel surface and fuel properties. Results show that flame spread rate increases exponentially with pressure, and the exponent of pressure further shows an increasing trend with the thickness of the sample. The angle of the pyrolysis front emerged on sample residue in the width direction, which indicates a steady-burning stage, varies clearly with sample thicknesses and ambient pressures. A global non-dimensional equation was proposed to predict the variation tendency of the angle of the pyrolysis front with pressure and was found to fit well with the measured results. In addition, the dependence of average flame height on mass burning rate, sample dimension and pressure was proposed based on laminar diffusion flame theory. The fitted exponent of experimental data is 1.11, which is close to the theoretical value. Full article

(This article belongs to the Special Issue Thermal Sciences and Thermodynamics of Materials)

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2384 KiB

Open AccessArticle

Optimizing Injection Molding Parameters of Different Halloysites Type-Reinforced Thermoplastic Polyurethane Nanocomposites via Taguchi Complemented with ANOVA

by Tayser Sumer Gaaz, Abu Bakar Sulong, Abdul Amir H. Kadhum, Mohamed H. Nassir and Ahmed A. Al-Amiery

Materials 2016, 9(11), 947; https://doi.org/10.3390/ma9110947 - 22 Nov 2016

Cited by 18 | Viewed by 6615

Abstract

Halloysite nanotubes-thermoplastic polyurethane (HNTs-TPU) nanocomposites are attractive products due to increasing demands for specialized materials. This study attempts to optimize the parameters for injection just before marketing. The study shows the importance of the preparation of the samples and how well these parameters [...] Read more.

Halloysite nanotubes-thermoplastic polyurethane (HNTs-TPU) nanocomposites are attractive products due to increasing demands for specialized materials. This study attempts to optimize the parameters for injection just before marketing. The study shows the importance of the preparation of the samples and how well these parameters play their roles in the injection. The control parameters for injection are carefully determined to examine the mechanical properties and the density of the HNTs-TPU nanocomposites. Three types of modified HNTs were used as untreated HNTs (uHNTs), sulfuric acid treated (aHNTs) and a combined treatment of polyvinyl alcohol (PVA)-sodium dodecyl sulfate (SDS)-malonic acid (MA) (treatment (mHNTs)). It was found that mHNTs have the most influential effect of producing HNTs-TPU nanocomposites with the best qualities. One possible reason for this extraordinary result is the effect of SDS as a disperser and MA as a crosslinker between HNTs and PVA. For the highest tensile strength, the control parameters are demonstrated at 150 °C (injection temperature), 8 bar (injection pressure), 30 °C (mold temperature), 8 min (injection time), 2 wt % (HNTs loading) and mHNT (HNTs type). Meanwhile, the optimized combination of the levels for all six control parameters that provide the highest Young’s modulus and highest density was found to be 150 °C (injection temperature), 8 bar (injection pressure), 32 °C (mold temperature), 8 min (injection time), 3 wt % (HNTs loading) and mHNT (HNTs type). For the best tensile strain, the six control parameters are found to be 160 °C (injection temperature), 8 bar (injection pressure), 32 °C (mold temperature), 8 min (injection time), 2 wt % (HNTs loading) and mHNT (HNTs type). For the highest hardness, the best parameters are 140 °C (injection temperature), 6 bar (injection pressure), 30 °C (mold temperature), 8 min (injection time), 2 wt % (HNTs loading) and mHNT (HNTs type). The analyses are carried out by coordinating Taguchi and ANOVA approaches. Seemingly, mHNTs has shown its very important role in the resulting product. Full article

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Open AccessArticle

A Bayesian Approach for Sensor Optimisation in Impact Identification

by Vincenzo Mallardo, Zahra Sharif Khodaei and Ferri M. H. Aliabadi

Materials 2016, 9(11), 946; https://doi.org/10.3390/ma9110946 - 22 Nov 2016

Cited by 31 | Viewed by 4962

Abstract

This paper presents a Bayesian approach for optimizing the position of sensors aimed at impact identification in composite structures under operational conditions. The uncertainty in the sensor data has been represented by statistical distributions of the recorded signals. An optimisation strategy based on [...] Read more.

This paper presents a Bayesian approach for optimizing the position of sensors aimed at impact identification in composite structures under operational conditions. The uncertainty in the sensor data has been represented by statistical distributions of the recorded signals. An optimisation strategy based on the genetic algorithm is proposed to find the best sensor combination aimed at locating impacts on composite structures. A Bayesian-based objective function is adopted in the optimisation procedure as an indicator of the performance of meta-models developed for different sensor combinations to locate various impact events. To represent a real structure under operational load and to increase the reliability of the Structural Health Monitoring (SHM) system, the probability of malfunctioning sensors is included in the optimisation. The reliability and the robustness of the procedure is tested with experimental and numerical examples. Finally, the proposed optimisation algorithm is applied to a composite stiffened panel for both the uniform and non-uniform probability of impact occurrence. Full article

(This article belongs to the Special Issue Advances in Structural Health Monitoring for Aerospace Structures)

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6222 KiB

Open AccessArticle

The Effect of Acceptor and Donor Doping on Oxygen Vacancy Concentrations in Lead Zirconate Titanate (PZT)

by Christoph Slouka, Theresa Kainz, Edvinas Navickas, Gregor Walch, Herbert Hutter, Klaus Reichmann and Jürgen Fleig

Materials 2016, 9(11), 945; https://doi.org/10.3390/ma9110945 - 22 Nov 2016

Cited by 68 | Viewed by 8857

Abstract

The different properties of acceptor-doped (hard) and donor-doped (soft) lead zirconate titanate (PZT) ceramics are often attributed to different amounts of oxygen vacancies introduced by the dopant. Acceptor doping is believed to cause high oxygen vacancy concentrations, while donors are expected to strongly [...] Read more.

The different properties of acceptor-doped (hard) and donor-doped (soft) lead zirconate titanate (PZT) ceramics are often attributed to different amounts of oxygen vacancies introduced by the dopant. Acceptor doping is believed to cause high oxygen vacancy concentrations, while donors are expected to strongly suppress their amount. In this study, La³⁺ donor-doped, Fe³⁺ acceptor-doped and La³⁺/Fe³⁺-co-doped PZT samples were investigated by oxygen tracer exchange and electrochemical impedance spectroscopy in order to analyse the effect of doping on oxygen vacancy concentrations. Relative changes in the tracer diffusion coefficients for different doping and quantitative relations between defect concentrations allowed estimates of oxygen vacancy concentrations. Donor doping does not completely suppress the formation of oxygen vacancies; rather, it concentrates them in the grain boundary region. Acceptor doping enhances the amount of oxygen vacancies but estimates suggest that bulk concentrations are still in the ppm range, even for 1% acceptor doping. Trapped holes might thus considerably contribute to the charge balancing of the acceptor dopants. This could also be of relevance in understanding the properties of hard and soft PZT. Full article

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9840 KiB

Open AccessArticle

Protein-Mediated Precipitation of Calcium Carbonate

by Izabela Polowczyk, Anna Bastrzyk and Marta Fiedot

Materials 2016, 9(11), 944; https://doi.org/10.3390/ma9110944 - 22 Nov 2016

Cited by 52 | Viewed by 7403

Abstract

Calcium carbonate is an important component in exoskeletons of many organisms. The synthesis of calcium carbonate was performed by mixing dimethyl carbonate and an aqueous solution of calcium chloride dihydrate. The precipitation product was characterized by means of scanning electron microscopy (SEM), transmission [...] Read more.

Calcium carbonate is an important component in exoskeletons of many organisms. The synthesis of calcium carbonate was performed by mixing dimethyl carbonate and an aqueous solution of calcium chloride dihydrate. The precipitation product was characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) measurements. In addition, the turbidity of the reaction solution was acquired to monitor the kinetics of the calcium carbonate structure’s growth in the investigated system. In this study, samples of CaCO₃ particles obtained with individual proteins, such as ovalbumin, lysozyme, and a mixture of the proteins, were characterized and compared with a control sample, i.e., synthesized without proteins. The obtained data indicated that the addition of ovalbumin to the reaction changed the morphology of crystals from rhombohedral to ‘stack-like’ structures. Lysozyme, however, did not affect the morphology of calcium carbonate, yet the presence of the protein mixture led to the creation of more complex composites in which the calcium carbonate crystals were constructed in protein matrices formed by the ovalbumin-lysozyme interaction. It was also observed that in the protein mixture, ovalbumin has a major influence on the CaCO₃ formation through a strong interaction with calcium ions, which leads to the coalescence and creation of a steric barrier reducing particle growth. The authors proposed a mechanism of calcium carbonate grain growth in the presence of both proteins, taking into account the interaction of calcium ions with the protein. Full article

(This article belongs to the Section Biomaterials)

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2671 KiB

Open AccessArticle

Targeted Magnetic Nanoparticles for Mechanical Lysis of Tumor Cells by Low-Amplitude Alternating Magnetic Field

by Adi Vegerhof, Eran A. Barnoy, Menachem Motiei, Dror Malka, Yossef Danan, Zeev Zalevsky and Rachela Popovtzer

Materials 2016, 9(11), 943; https://doi.org/10.3390/ma9110943 - 22 Nov 2016

Cited by 22 | Viewed by 7036

Abstract

Currently available cancer therapies can cause damage to healthy tissue. We developed a unique method for specific mechanical lysis of cancer cells using superparamagnetic iron oxide nanoparticle rotation under a weak alternating magnetic field. Iron oxide core nanoparticles were coated with cetuximab, an [...] Read more.

Currently available cancer therapies can cause damage to healthy tissue. We developed a unique method for specific mechanical lysis of cancer cells using superparamagnetic iron oxide nanoparticle rotation under a weak alternating magnetic field. Iron oxide core nanoparticles were coated with cetuximab, an anti-epidermal growth factor receptor antibody, for specific tumor targeting. Nude mice bearing a head and neck tumor were treated with cetuximab-coated magnetic nanoparticles (MNPs) and then received a 30 min treatment with a weak external alternating magnetic field (4 Hz) applied on alternating days (total of seven treatments, over 14 days). This treatment, compared to a pure antibody, exhibited a superior cell death effect over time. Furthermore, necrosis in the tumor site was detected by magnetic resonance (MR) images. Thermal camera images of head and neck squamous cell carcinoma cultures demonstrated that cell death occurred purely by a mechanical mechanism. Full article

(This article belongs to the Special Issue Nanoprobes for Imaging)

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2369 KiB

Open AccessArticle

Experimental and Theoretical Analysis of Sound Absorption Properties of Finely Perforated Wooden Panels

by Boqi Song, Limin Peng, Feng Fu, Meihong Liu and Houjiang Zhang

Materials 2016, 9(11), 942; https://doi.org/10.3390/ma9110942 - 22 Nov 2016

Cited by 23 | Viewed by 5842

Abstract

Perforated wooden panels are typically utilized as a resonant sound absorbing material in indoor noise control. In this paper, the absorption properties of wooden panels perforated with tiny holes of 1–3 mm diameter were studied both experimentally and theoretically. The Maa-MPP (micro perforated [...] Read more.

Perforated wooden panels are typically utilized as a resonant sound absorbing material in indoor noise control. In this paper, the absorption properties of wooden panels perforated with tiny holes of 1–3 mm diameter were studied both experimentally and theoretically. The Maa-MPP (micro perforated panels) model and the Maa-Flex model were applied to predict the absorption regularities of finely perforated wooden panels. A relative impedance comparison and full-factorial experiments were carried out to verify the feasibility of the theoretical models. The results showed that the Maa-Flex model obtained good agreement with measured results. Control experiments and measurements of dynamic mechanical properties were carried out to investigate the influence of the wood characteristics. In this study, absorption properties were enhanced by sound-induced vibration. The relationship between the dynamic mechanical properties and the panel mass-spring vibration absorption was revealed. While the absorption effects of wood porous structure were not found, they were demonstrated theoretically by using acoustic wave propagation in a simplified circular pipe with a suddenly changed cross-section model. This work provides experimental and theoretical guidance for perforation parameter design. Full article

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6996 KiB

Open AccessArticle

Laboratory Testing of Silica Sol Grout in Coal Measure Mudstones

by Dongjiang Pan, Nong Zhang, Zhengzheng Xie, Xiaowei Feng and Yong Kong

Materials 2016, 9(11), 940; https://doi.org/10.3390/ma9110940 - 22 Nov 2016

Cited by 16 | Viewed by 6614

Abstract

The effectiveness of silica sol grout on mudstones is reported in this paper. Using X-ray diffraction (XRD), the study investigates how the silica sol grout modifies mudstone mineralogy. Micropore sizes and mechanical properties of the mudstone before and after grouting with four different [...] Read more.

The effectiveness of silica sol grout on mudstones is reported in this paper. Using X-ray diffraction (XRD), the study investigates how the silica sol grout modifies mudstone mineralogy. Micropore sizes and mechanical properties of the mudstone before and after grouting with four different materials were determined with a surface area/porosity analyser and by uniaxial compression. Tests show that, after grouting, up to 50% of the mesopore volumes can be filled with grout, the dominant pore diameter decreases from 100 nm to 10 nm, and the sealing capacity is increased. Uniaxial compression tests of silica sol grouted samples shows that their elastic modulus is 21%–38% and their uniaxial compressive strength is 16%–54% of the non-grouted samples. Peak strain, however, is greater by 150%–270%. After grouting, the sample failure mode changes from brittle to ductile. This paper provides an experimental test of anti-seepage and strengthening properties of silica sol. Full article

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12959 KiB

Open AccessArticle

Efficient Solar-Induced Photoelectrochemical Response Using Coupling Semiconductor TiO₂-ZnO Nanorod Film

by Nur Azimah Abd Samad, Chin Wei Lai, Kung Shiuh Lau and Sharifah Bee Abd Hamid

Materials 2016, 9(11), 937; https://doi.org/10.3390/ma9110937 - 22 Nov 2016

Cited by 15 | Viewed by 6823

Abstract

Efficient solar driven photoelectrochemical (PEC) response by enhancing charge separation has attracted great interest in the hydrogen generation application. The formation of one-dimensional ZnO nanorod structure without bundling is essential for high efficiency in PEC response. In this present research work, ZnO nanorod [...] Read more.

Efficient solar driven photoelectrochemical (PEC) response by enhancing charge separation has attracted great interest in the hydrogen generation application. The formation of one-dimensional ZnO nanorod structure without bundling is essential for high efficiency in PEC response. In this present research work, ZnO nanorod with an average 500 nm in length and average diameter of about 75 nm was successfully formed via electrodeposition method in 0.05 mM ZnCl₂ and 0.1 M KCl electrolyte at 1 V for 60 min under 70 °C condition. Continuous efforts have been exerted to further improve the solar driven PEC response by incorporating an optimum content of TiO₂ into ZnO nanorod using dip-coating technique. It was found that 0.25 at % of TiO₂ loaded on ZnO nanorod film demonstrated a maximum photocurrent density of 19.78 mA/cm² (with V vs. Ag/AgCl) under UV illumination and 14.75 mA/cm² (with V vs. Ag/AgCl) under solar illumination with photoconversion efficiency ~2.9% (UV illumination) and ~4.3% (solar illumination). This performance was approximately 3–4 times higher than ZnO film itself. An enhancement of photocurrent density and photoconversion efficiency occurred due to the sufficient Ti element within TiO₂-ZnO nanorod film, which acted as an effective mediator to trap the photo-induced electrons and minimize the recombination of charge carriers. Besides, phenomenon of charge-separation effect at type-II band alignment of Zn and Ti could further enhance the charge carrier transportation during illumination. Full article

(This article belongs to the Special Issue Thin-Film Deposition, Characterization and Advanced Surface Engineering)

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Open AccessArticle

Numerical Approach to Modeling and Characterization of Refractive Index Changes for a Long-Period Fiber Grating Fabricated by Femtosecond Laser

by Akram Saad, Yonghyun Cho, Farid Ahmed and Martin Byung-Guk Jun

Materials 2016, 9(11), 941; https://doi.org/10.3390/ma9110941 - 21 Nov 2016

Cited by 3 | Viewed by 6261

Abstract

A 3D finite element model constructed to predict the intensity-dependent refractive index profile induced by femtosecond laser radiation is presented. A fiber core irradiated by a pulsed laser is modeled as a cylinder subject to predefined boundary conditions using COMSOL5.2 Multiphysics commercial package. [...] Read more.

A 3D finite element model constructed to predict the intensity-dependent refractive index profile induced by femtosecond laser radiation is presented. A fiber core irradiated by a pulsed laser is modeled as a cylinder subject to predefined boundary conditions using COMSOL5.2 Multiphysics commercial package. The numerically obtained refractive index change is used to numerically design and experimentally fabricate long-period fiber grating (LPFG) in pure silica core single-mode fiber employing identical laser conditions. To reduce the high computational requirements, the beam envelope method approach is utilized in the aforementioned numerical models. The number of periods, grating length, and grating period considered in this work are numerically quantified. The numerically obtained spectral growth of the modeled LPFG seems to be consistent with the transmission of the experimentally fabricated LPFG single mode fiber. The sensing capabilities of the modeled LPFG are tested by varying the refractive index of the surrounding medium. The numerically obtained spectrum corresponding to the varied refractive index shows good agreement with the experimental findings. Full article

(This article belongs to the Special Issue Ultrafast Laser-Based Manufacturing)

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5255 KiB

Open AccessArticle

Effects of Acoustic Modulation and Mixed Fuel on Flame Synthesis of Carbon Nanomaterials in an Atmospheric Environment

by Wei-Chieh Hu, Shanti Kartika Sari, Shuhn-Shyurng Hou and Ta-Hui Lin

Materials 2016, 9(11), 939; https://doi.org/10.3390/ma9110939 - 18 Nov 2016

Cited by 7 | Viewed by 4662

Abstract

In this study, methane–ethylene jet diffusion flames modulated by acoustic excitation in an atmospheric environment were used to investigate the effects of acoustic excitation frequency and mixed fuel on nanomaterial formation. Acoustic output power was maintained at a constant value of 10 W, [...] Read more.

In this study, methane–ethylene jet diffusion flames modulated by acoustic excitation in an atmospheric environment were used to investigate the effects of acoustic excitation frequency and mixed fuel on nanomaterial formation. Acoustic output power was maintained at a constant value of 10 W, while the acoustic excitation frequency was varied (f = 0–90 Hz). The results show that the flame could not be stabilized on the port when the ethylene volume concentration (Ω_E) was less than 40% at f = 10 Hz, or when Ω_E = 0% (i.e., pure methane) at f = 90 Hz. The reason for this is that the flame had a low intensity and was extinguished by the entrained air due to acoustic modulation. Without acoustic excitation (f = 0 Hz), the flame was comprised of a single-layer structure for all values of Ω_E, and almost no carbon nanomaterials were synthesized. However, with acoustic excitation, a double-layer flame structure was generated for frequencies close to both the natural flickering frequency and the acoustically resonant frequency. This double-layer flame structure provided a favorable flame environment for the fabrication of carbon nanomaterials. Consequently, the synthesis of carbon nano-onions was significantly enhanced by acoustic excitation near both the natural flickering frequency and the acoustically resonant frequency. At f = 20 Hz (near the natural flickering frequency) for 0% ≤ Ω_E ≤ 100%, a quantity of carbon nano-onions (CNOs) piled like bunches of grapes was obtained as a result of improved mixing of the fuel with ambient air. High-density CNOs were also produced at f = 70 Hz (close to the acoustically resonant frequency) for 40% ≤ Ω_E ≤ 100%. Furthermore, carbon nanotubes (CNTs) were synthesized only at 80 Hz for Ω_E = 0%. The suitable temperature range for the synthesis of CNTs was slightly higher than that for the formation of CNOs (about 600 °C for CNTs; 510–600 °C for CNOs). Full article

(This article belongs to the Special Issue Selected Papers from ICASI 2016)

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4961 KiB

Open AccessFeature PaperArticle

Molecular Weight Cut-Off and Structural Analysis of Vacuum-Assisted Titania Membranes for Water Processing

by Siti Nurehan Abd Jalil, David K. Wang, Christelle Yacou, Julius Motuzas, Simon Smart and João C. Diniz da Costa

Materials 2016, 9(11), 938; https://doi.org/10.3390/ma9110938 - 18 Nov 2016

Cited by 6 | Viewed by 6150

Abstract

This work investigates the structural formation and analyses of titania membranes (TM) prepared using different vacuum exposure times for molecular weight (MW) cut-off performance and oil/water separation. Titania membranes were synthesized via a sol-gel method and coated on macroporous alumina tubes followed by [...] Read more.

This work investigates the structural formation and analyses of titania membranes (TM) prepared using different vacuum exposure times for molecular weight (MW) cut-off performance and oil/water separation. Titania membranes were synthesized via a sol-gel method and coated on macroporous alumina tubes followed by exposure to a vacuum between 30 and 1200 s and then calcined at 400 °C. X-ray diffraction and nitrogen adsorption analyses showed that the crystallite size and particle size of titania increased as a function of vacuum time. All the TM membranes were mesoporous with an average pore diameter of ~3.6 nm with an anatase crystal morphology. Water, glucose, sucrose, and polyvinylpyrrolidone with 40 and 360 kDa (PVP-40 kDa and PVP-360 kDa) were used as feed solutions for MW cut-off and hexadecane solution for oil filtration investigation. The TM membranes were not able to separate glucose and sucrose, thus indicating the membrane pore sizes are larger than the kinetic diameter of sucrose of 0.9 nm, irrespective of vacuum exposure time. They also showed only moderate rejection (20%) of the smaller PVP-40 kDa, however, all the membranes were able to obtain an excellent rejection of near 100% for the larger PVP-360 kDa molecule. Furthermore, the TM membranes were tested for the separation of oil emulsions with a high concentration of oil (3000 ppm), reaching high oil rejections of more than 90% of oil. In general, the water fluxes increased with the vacuum exposure time indicating a pore structural tailoring effect. It is therefore proposed that a mechanism of pore size tailoring was formed by an interconnected network of Ti–O–Ti nanoparticles with inter-particle voids, which increased as TiO₂ nanoparticle size increased as a function of vacuum exposure time, and thus reduced the water transport resistance through the TM membranes. Full article

(This article belongs to the Special Issue Porous Materials for Water Technology)

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20975 KiB

Open AccessArticle

Experimental Study on Reaction Characteristics of PTFE/Ti/W Energetic Materials under Explosive Loading

by Yan Li, Chunlan Jiang, Zaicheng Wang and Puguang Luo

Materials 2016, 9(11), 936; https://doi.org/10.3390/ma9110936 - 18 Nov 2016

Cited by 21 | Viewed by 6371

Abstract

Metal/fluoropolymer composites represent a new category of energetic structural materials that release energy through exothermic chemical reactions initiated under shock loading conditions. This paper describes an experiment designed to study the reaction characteristics of energetic materials with low porosity under explosive loading. Three [...] Read more.

Metal/fluoropolymer composites represent a new category of energetic structural materials that release energy through exothermic chemical reactions initiated under shock loading conditions. This paper describes an experiment designed to study the reaction characteristics of energetic materials with low porosity under explosive loading. Three PTFE (polytetrafluoroethylene)/Ti/W mixtures with different W contents are processed through pressing and sintering. An inert PTFE/W mixture without reactive Ti particles is also prepared to serve as a reference. Shock-induced chemical reactions are recorded by high-speed video through a narrow observation window. Related shock parameters are calculated based on experimental data, and differences in energy release are discussed. The results show that the reaction propagation of PTFE/Ti/W energetic materials with low porosity under explosive loading is not self-sustained. As propagation distance increases, the energy release gradually decreases. In addition, reaction failure distance in PTFE/Ti/W composites is inversely proportional to the W content. Porosity increased the failure distance due to higher shock temperature. Full article

(This article belongs to the Section Advanced Composites)

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2210 KiB

Open AccessFeature PaperCommunication

Energy Storage Characteristics of BiFeO₃/BaTiO₃ Bi-Layers Integrated on Si

by Menglin Liu, Hanfei Zhu, Yunxiang Zhang, Caihong Xue and Jun Ouyang

Materials 2016, 9(11), 935; https://doi.org/10.3390/ma9110935 - 18 Nov 2016

Cited by 39 | Viewed by 6978

Abstract

BiFeO₃/BaTiO₃ bi-layer thick films (~1 μm) were deposited on Pt/Ti/SiO₂/(100) Si substrates with LaNiO₃ buffer layers at 500 °C via a rf magnetron sputtering process. X-ray diffraction (XRD) analysis revealed that both BiFeO₃ and BaTiO₃ [...] Read more.

BiFeO₃/BaTiO₃ bi-layer thick films (~1 μm) were deposited on Pt/Ti/SiO₂/(100) Si substrates with LaNiO₃ buffer layers at 500 °C via a rf magnetron sputtering process. X-ray diffraction (XRD) analysis revealed that both BiFeO₃ and BaTiO₃ layers have a (00l) preferred orientation. The films showed a small remnant polarization (P_r ~ 7.8 μC/cm²) and a large saturated polarization (Ps ~ 65 μC/cm²), resulting in a slim polarization-electric field (P-E) hysteresis loop with improved energy storage characteristics (W_c = 71 J/cm³, η = 61%). The successful “slim-down” of the P-E loop from that of the pure BiFeO₃ film can be attributed to the competing effects of space charges and the interlayer charge coupling on charge transport of the bi-layer film. The accompanying electrical properties of the bi-layer films were measured and the results confirmed their good quality. Full article

(This article belongs to the Special Issue Microwave Absorbing and Energy Storage Materials)

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8045 KiB

Open AccessArticle

Characterization and Bioactivity Evaluation of (Polyetheretherketone/Polyglycolicacid)-Hydroyapatite Scaffolds for Tissue Regeneration

by Cijun Shuai, Chenying Shuai, Ping Wu, Fulai Yuan, Pei Feng, Youwen Yang, Wang Guo, Xiaohan Fan, Ting Su, Shuping Peng and Chengde Gao

Materials 2016, 9(11), 934; https://doi.org/10.3390/ma9110934 - 18 Nov 2016

Cited by 29 | Viewed by 5171

Abstract

Bioactivity and biocompatibility are crucial for tissue engineering scaffolds. In this study, hydroxyapatite (HAP) was incorporated into polyetheretherketone/polyglycolicacid (PEEK/PGA) hybrid to improve its biological properties, and the composite scaffolds were developed via selective laser sintering (SLS). The effects of HAP on physical and [...] Read more.

Bioactivity and biocompatibility are crucial for tissue engineering scaffolds. In this study, hydroxyapatite (HAP) was incorporated into polyetheretherketone/polyglycolicacid (PEEK/PGA) hybrid to improve its biological properties, and the composite scaffolds were developed via selective laser sintering (SLS). The effects of HAP on physical and chemical properties of the composite scaffolds were investigated. The results demonstrated that HAP particles were distributed evenly in PEEK/PGA matrix when its content was no more than 10 wt %. Furthermore, the apatite-forming ability became better with increasing HAP content after immersing in simulated body fluid (SBF). Meanwhile, the composite scaffolds presented a greater degree of cell attachment and proliferation than PEEK/PGA scaffolds. These results highlighted the potential of (PEEK/PGA)-HAP scaffolds for tissue regeneration. Full article

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11186 KiB

Open AccessArticle

Studying the Hydration of a Retarded Suspension of Ground Granulated Blast-Furnace Slag after Reactivation

by Nick Schneider and Dietmar Stephan

Materials 2016, 9(11), 933; https://doi.org/10.3390/ma9110933 - 18 Nov 2016

Cited by 2 | Viewed by 4707

Abstract

This article presents a combined use of a retarder (d-gluconic acid) and an alkaline activator (sodium hydroxide) in a binder system based on ground granulated blast-furnace slag. The properties of the retarder are extending the dormant hydration period and suppressing the [...] Read more.

This article presents a combined use of a retarder (d-gluconic acid) and an alkaline activator (sodium hydroxide) in a binder system based on ground granulated blast-furnace slag. The properties of the retarder are extending the dormant hydration period and suppressing the generation of strength-giving phases. Different retarder concentrations between 0.25 and 1.00 wt.% regulate the intensity and the period of the retardation and also the characteristics of the strength development. The activator concentration of 30 and 50 wt.% regulates the overcoming of the dormant period and thereby the solution of the slag and hence the formation of the hydration products. The research objective is to produce a mineral binder system based on two separate liquid components. The highest concentration of retarder and activator generates the highest compressive strength and mass of hydration products—after 90 days of hydration a compressive strength of more than 50 N/mm². The main phases are calcium silicate hydrate and hydrotalcite. Generally, the combination of retarder and activator shows a high potential in the performance increase of the hydration process. Full article

(This article belongs to the Section Advanced Composites)

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5991 KiB

Open AccessArticle

Evaluating and Modeling the Internal Diffusion Behaviors of Microencapsulated Rejuvenator in Aged Bitumen by FTIR-ATR Tests

by Junfeng Su, Yingyuan Wang, Peng Yang, Shan Han, Ningxu Han and Wei Li

Materials 2016, 9(11), 932; https://doi.org/10.3390/ma9110932 - 17 Nov 2016

Cited by 26 | Viewed by 4979

Abstract

Microencapsulated rejuvenator has been attracted much attention for self-healing bitumen. The diffusion coefficient is one of the key parameters to estimate the feasibility of rejuvenator to age bitumen. The objective of this research was to evaluate diffusion behaviors of microencapsulated rejuvenator in aged [...] Read more.

Microencapsulated rejuvenator has been attracted much attention for self-healing bitumen. The diffusion coefficient is one of the key parameters to estimate the feasibility of rejuvenator to age bitumen. The objective of this research was to evaluate diffusion behaviors of microencapsulated rejuvenator in aged bitumen by a FTIR-ATR method. Various microcapsule samples were mixed in bitumen to form thin films. The core material of microcapsules used as rejuvenator was diphenylsilane (DPS), its fairly specific absorption band at 843 cm⁻¹ was selected as a marker band to calculate the diffusion coefficient (D). The microstructure parameters, including contents, mean size and mean shell thickness of microcapsules, were considered to understand the diffusion behaviors under different temperatures (20, 30, 40 and 50 °C) in bitumen. The results showed that a larger mean size of microcapsules did not greatly affect the D values under the same temperature. In contrast, a higher mean shell thickness decreased the D values because of the decrement of damage probability of microcapsules under the same content. With the same microcapsule sample in bitumen, the D values presented a trend of linear increase when the content of microcapsules was increased. All these results indicated that the microstructure affected the diffusion behaviors based on the concentration of released rejuvenator. A preliminary model of diffusion behaviors of microencapsulated rejuvenator in bitumen was given based on the Arrhenius equation considering the microstructure of microcapsules, the amount of released rejuvenator and the age degree of bitumen. This model may be a guide to the construction and application of self-healing bitumen using microcapsules. Full article

(This article belongs to the Section Advanced Materials Characterization)

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7616 KiB

Open AccessArticle

Feasibility of Using Unbound Mixed Recycled Aggregates from CDW over Expansive Clay Subgrade in Unpaved Rural Roads

by Isaac Del Rey, Jesús Ayuso, Adela P. Galvín, José R. Jiménez and Auxi Barbudo

Materials 2016, 9(11), 931; https://doi.org/10.3390/ma9110931 - 17 Nov 2016

Cited by 30 | Viewed by 5599

Abstract

Social awareness aims to increase practical skills, such as sustainable development, which seeks to increase the use of different types of waste in construction activities. Although insufficient attention is sometimes given to these actions, it is essential to spread information regarding new studies [...] Read more.

Social awareness aims to increase practical skills, such as sustainable development, which seeks to increase the use of different types of waste in construction activities. Although insufficient attention is sometimes given to these actions, it is essential to spread information regarding new studies in the field of waste recycling, which encourages and promotes waste use. Reusing and recycling construction waste in the creation of buildings and infrastructure are fundamental strategies to achieving sustainability in the construction and engineering sectors. In this context, the concept of waste would no longer exist, as waste would become a material resource. Therefore, this study analyses the behaviours of two unbound mixed recycled aggregates (MRA) in the structural layers of an unpaved rural road with low traffic (category T43). The sections were built on inappropriate soil (A-7-6) with a high degree of free swelling. The experimental road consisted of three sections: the first was made with natural aggregates (NA) that were used as a control, the second was composed of MRA in the subbase and NA in the base, and the third section was completely composed of MRA. The materials were characterised in the laboratory. The behaviours of the structural layers in the experimental road were determined by controlling compaction (“in situ” density and moisture) and measuring the deflections and load capacity (deflectometer) during the 18 months after construction. The results show that the sections made with recycled aggregates meet the technical specifications required by General Technical Specifications for Road and Bridge Works (PG-3). Therefore, the water-soluble sulphate content and Los Angeles abrasion coefficient limits can be increased for recycled aggregates without compromising the quality of this type of road with low traffic. To the best of our knowledge, this is the first study regarding the use of unbound MRA made from construction and demolition waste (CDW) in the construction of an unpaved rural road with low traffic on an expansive clay subgrade. Full article

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5960 KiB

Open AccessArticle

Separation of Hydrogen from Carbon Dioxide through Porous Ceramics

by Taro Shimonosono, Hikari Imada, Hikaru Maeda and Yoshihiro Hirata

Materials 2016, 9(11), 930; https://doi.org/10.3390/ma9110930 - 16 Nov 2016

Cited by 9 | Viewed by 5750

Abstract

The gas permeability of α-alumina, yttria-stabilized zirconia (YSZ), and silicon carbide porous ceramics toward H₂, CO₂, and H₂–CO₂ mixtures were investigated at room temperature. The permeation of H₂ and CO₂ single gases occurred above [...] Read more.

The gas permeability of α-alumina, yttria-stabilized zirconia (YSZ), and silicon carbide porous ceramics toward H₂, CO₂, and H₂–CO₂ mixtures were investigated at room temperature. The permeation of H₂ and CO₂ single gases occurred above a critical pressure gradient, which was smaller for H₂ gas than for CO₂ gas. When the Knudsen number (λ/r ratio, λ: molecular mean free path, r: pore radius) of a single gas was larger than unity, Knudsen flow became the dominant gas transportation process. The H₂ fraction for the mixed gas of (20%–80%) H₂–(80%–20%) CO₂ through porous Al₂O₃, YSZ, and SiC approached unity with decreasing pressure gradient. The high fraction of H₂ gas was closely related to the difference in the critical pressure gradient values of H₂ and CO₂ single gas, the inlet mixed gas composition, and the gas flow mechanism of the mixed gas. Moisture in the atmosphere adsorbed easily on the porous ceramics and affected the critical pressure gradient, leading to the increased selectivity of H₂ gas. Full article

(This article belongs to the Special Issue Porous Ceramics)

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19303 KiB

Open AccessArticle

Freckle Defect Formation near the Casting Interfaces of Directionally Solidified Superalloys

by Jianping Hong, Dexin Ma, Jun Wang, Fu Wang, Baode Sun, Anping Dong, Fei Li and Andreas Bührig-Polaczek

Materials 2016, 9(11), 929; https://doi.org/10.3390/ma9110929 - 16 Nov 2016

Cited by 25 | Viewed by 8553

Abstract

Freckle defects usually appear on the surface of castings and industrial ingots during the directional solidification process and most of them are located near the interface between the shell mold and superalloys. Ceramic cores create more interfaces in the directionally solidified (DS) and [...] Read more.

Freckle defects usually appear on the surface of castings and industrial ingots during the directional solidification process and most of them are located near the interface between the shell mold and superalloys. Ceramic cores create more interfaces in the directionally solidified (DS) and single crystal (SX) hollow turbine blades. In order to investigate the location of freckle occurrence in superalloys, superalloy CM247 LC was directionally solidified in an industrial-sized Bridgman furnace. Instead of ceramic cores, Alumina tubes were used inside of the casting specimens. It was found that freckles occur not only on the casting external surfaces, but also appear near the internal interfaces between the ceramic core and superalloys. Meanwhile, the size, initial position, and area of freckle were investigated in various diameters of the specimens. The initial position of the freckle chain reduces when the diameter of the rods increase. Freckle area follows a linear relationship in various diameters and the average freckle fraction is 1.1% of cross sectional area of casting specimens. The flow of liquid metal near the interfaces was stronger than that in the interdendritic region in the mushy zone, and explained why freckle tends to occur on the outer or inner surfaces of castings. This new phenomenon suggests that freckles are more likely to occur on the outer or inner surfaces of the hollow turbine blades. Full article

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2066 KiB

Open AccessCommunication

Mechanical Properties and In Vitro Degradation of Sputtered Biodegradable Fe-Au Foils

by Till Jurgeleit, Eckhard Quandt and Christiane Zamponi

Materials 2016, 9(11), 928; https://doi.org/10.3390/ma9110928 - 15 Nov 2016

Cited by 7 | Viewed by 3452

Abstract

Iron-based materials proved being a viable candidate material for biodegradable implants. Magnetron sputtering combined with UV-lithography offers the possibility to fabricate structured, freestanding foils of iron-based alloys and even composites with non-solvable elements. In order to accelerate the degradation speed and enhance the [...] Read more.

Iron-based materials proved being a viable candidate material for biodegradable implants. Magnetron sputtering combined with UV-lithography offers the possibility to fabricate structured, freestanding foils of iron-based alloys and even composites with non-solvable elements. In order to accelerate the degradation speed and enhance the mechanical properties, the technique was used to fabricate Fe-Au multilayer foils. The foils were annealed after the deposition to form a homogeneous microstructure with fine Au precipitates. The characterization of the mechanical properties was done by uniaxial tensile tests. The degradation behavior was analyzed by electrochemical tests and immersion tests under in vitro conditions. Due to the noble Au precipitates it was possible to achieve high tensile strengths between 550 and 800 MPa depending on the Au content and heat treatment. Furthermore, the Fe-Au foils showed a significantly accelerated corrosion compared to pure iron samples. The high mechanical strength is close to the properties of SS316L steel. In combination with the accelerated degradation rate, sputtered Fe-Au foils showed promising properties for use as iron-based, biodegradable implants. Full article

(This article belongs to the Section Biomaterials)

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3191 KiB

Open AccessArticle

ZnO-Layered Double Hydroxide@Graphitic Carbon Nitride Composite for Consecutive Adsorption and Photodegradation of Dyes under UV and Visible Lights

by Luhong Zhang, Li Li, Xiaoming Sun, Peng Liu, Dongfang Yang and Xiusong Zhao

Materials 2016, 9(11), 927; https://doi.org/10.3390/ma9110927 - 15 Nov 2016

Cited by 52 | Viewed by 8284

Abstract

In this work, a ZnO-layered double hydroxide@graphitic carbon nitride composite (ZnO-LDH@C₃N₄) was synthesized via co-precipitation method with solvothermal treatment. The structure and morphology of ZnO-LDH@C₃N₄ composite were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy [...] Read more.

In this work, a ZnO-layered double hydroxide@graphitic carbon nitride composite (ZnO-LDH@C₃N₄) was synthesized via co-precipitation method with solvothermal treatment. The structure and morphology of ZnO-LDH@C₃N₄ composite were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopes/transmission electron microscopes (SEM/TEM), N₂ adsorption/desorption, ultraviolet visible diffuse reflectance spectroscopy (UV-Vis-DRS), photoluminescence spectrometer (PL) and electrochemical impedance spectroscopy (EIS). The adsorption and photocatalytic properties of ZnO-LDH@C₃N₄ composite towards the organic dyes: Orange II sodium salt (OrgII, an anionic azo dye) and methylene blue (MB, a cationic azo dye) were investigated. Compared to ZnO-LDH and g-C₃N₄, the ZnO-LDH@C₃N₄ composite displayed an excellent performance in both adsorption and photocatalytic degradation of the organic dyes. Moreover, a combination of ZnO-LDH and g-C₃N₄ significantly improved the photocatalytic performance of ZnO-LDH and g-C₃N₄ under visible-light irradiation. The adsorption and photocatalytic mechanism were also investigated. Full article

(This article belongs to the Special Issue Porous Materials for Water Technology)

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5407 KiB

Open AccessArticle

Tissue-Like Phantoms as a Platform for Inserted Fluorescence Nano-Probes

by Tsviya Nayhoz, Eran A. Barnoy and Dror Fixler

Materials 2016, 9(11), 926; https://doi.org/10.3390/ma9110926 - 15 Nov 2016

Cited by 7 | Viewed by 5467

Abstract

Tissue-like phantoms are widely used as a model for mimicking the optical properties of live tissue. This paper presents the results of a diffusion reflection method and fluorescence lifetime imaging microscopy measurements of fluorescein-conjugated gold nanorods in solution, as well as inserted in [...] Read more.

Tissue-like phantoms are widely used as a model for mimicking the optical properties of live tissue. This paper presents the results of a diffusion reflection method and fluorescence lifetime imaging microscopy measurements of fluorescein-conjugated gold nanorods in solution, as well as inserted in solid tissue-imitating phantoms. A lack of consistency between the fluorescence lifetime results of the solutions and the phantoms raises a question about the ability of tissue-like phantoms to maintain the optical properties of inserted contrast agents. Full article

(This article belongs to the Special Issue Nanoprobes for Imaging)

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2235 KiB

Open AccessArticle

Comparison of Electrochemical Methods for the Evaluation of Cast AZ91 Magnesium Alloy

by Jakub Tkacz, Jozef Minda, Stanislava Fintová and Jaromír Wasserbauer

Materials 2016, 9(11), 925; https://doi.org/10.3390/ma9110925 - 15 Nov 2016

Cited by 40 | Viewed by 6628

Abstract

Linear polarization is a potentiodynamic method used for electrochemical characterization of materials. Obtained values of corrosion potential and corrosion current density offer information about material behavior in corrosion environments from the thermodynamic and kinetic points of view, respectively. The present study offers a [...] Read more.

Linear polarization is a potentiodynamic method used for electrochemical characterization of materials. Obtained values of corrosion potential and corrosion current density offer information about material behavior in corrosion environments from the thermodynamic and kinetic points of view, respectively. The present study offers a comparison of applications of the linear polarization method (from −100 mV to +200 mV vs. E_OCP), the cathodic polarization of the specimen (−100 mV vs. E_OCP), and the anodic polarization of the specimen (+100 mV vs. E_OCP), and a discussion of the differences in the obtained values of the electrochemical characteristics of cast AZ91 magnesium alloy. The corrosion current density obtained by cathodic polarization was similar to the corrosion current density obtained by linear polarization, while a lower value was obtained by anodic polarization. Signs of corrosion attack were observed only in the case of linear polarization including cathodic and anodic polarization of the specimen. Full article

(This article belongs to the Special Issue Degradable Biomaterials Based on Magnesium Alloys)

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