Materials

2899 KiB

Open AccessFeature PaperArticle

Development of Porous Piezoceramics for Medical and Sensor Applications

by Erling Ringgaard, Frans Lautzenhiser, Louise M. Bierregaard, Tomasz Zawada and Eric Molz

Materials 2015, 8(12), 8877-8889; https://doi.org/10.3390/ma8125498 - 21 Dec 2015

Cited by 32 | Viewed by 6001

The use of porosity to modify the functional properties of piezoelectric ceramics is well known in the scientific literature as well as by the industry, and porous ceramic can be seen as a 2-phase composite. In the present work, examples are given of [...] Read more.

The use of porosity to modify the functional properties of piezoelectric ceramics is well known in the scientific literature as well as by the industry, and porous ceramic can be seen as a 2-phase composite. In the present work, examples are given of applications where controlled porosity is exploited in order to optimise the dielectric, piezoelectric and acoustic properties of the piezoceramics. For the optimisation efforts it is important to note that the thickness coupling coefficient k_t will be maximised for some non-zero value of the porosity that could be above 20%. On the other hand, with a good approximation, the acoustic velocity decreases linearly with increasing porosity, which is obviously also the case for the density. Consequently, the acoustic impedance shows a rather strong decrease with porosity, and in practice a reduction of more than 50% may be obtained for an engineered porous ceramic. The significance of the acoustic impedance is associated with the transmission of acoustic signals through the interface between the piezoceramic and some medium of propagation, but when the porous ceramic is used as a substrate for a piezoceramic thick film, the attenuation may be equally important. In the case of open porosity it is possible to introduce a liquid into the pores, and examples of modifying the properties in this way are given. Full article

(This article belongs to the Special Issue Piezoelectric Materials)

► Show Figures

Figure 1

16491 KiB

Open AccessArticle

Surface Effects and Challenges for Application of Piezoelectric Langasite Substrates in Surface Acoustic Wave Devices Caused by High Temperature Annealing under High Vacuum

by Marietta Seifert, Gayatri K Rane, Benjamin Kirbus, Siegfried B Menzel and Thomas Gemming

Materials 2015, 8(12), 8868-8876; https://doi.org/10.3390/ma8125497 - 19 Dec 2015

Cited by 6 | Viewed by 4615

Abstract

Substrate materials that are high-temperature stable are essential for sensor devices which are applied at high temperatures. Although langasite is suggested as such a material, severe O and Ga diffusion into an O-affine deposited film was observed during annealing at high temperatures under [...] Read more.

Substrate materials that are high-temperature stable are essential for sensor devices which are applied at high temperatures. Although langasite is suggested as such a material, severe O and Ga diffusion into an O-affine deposited film was observed during annealing at high temperatures under vacuum conditions, leading to a damage of the metallization as well as a change of the properties of the substrate and finally to a failure of the device. Therefore, annealing of bare LGS (La 3 Ga 5 SiO 14 ) substrates at 800 ∘ C under high vacuum conditions is performed to analyze whether this pretreatment improves the suitability and stability of this material for high temperature applications in vacuum. To reveal the influence of the pretreatment on the subsequently deposited metallization, RuAl thin films are used as they are known to oxidize on LGS at high temperatures. A local study of the pretreated and metallized substrates using transmission electron microscopy reveals strong modification of the substrate surface. Micro cracks are visible. The composition of the substrate is strongly altered at those regions. Severe challenges for the application of LGS substrates under high-temperature vacuum conditions arise from these substrate damages, revealing that the pretreatment does not improve the applicability. Full article

(This article belongs to the Section Advanced Composites)

► Show Figures

Graphical abstract

2377 KiB

Open AccessArticle

Efficiency Enhancement of Dye-Sensitized Solar Cells’ Performance with ZnO Nanorods Grown by Low-Temperature Hydrothermal Reaction

by Fang-I Lai, Jui-Fu Yang and Shou-Yi Kuo

Materials 2015, 8(12), 8860-8867; https://doi.org/10.3390/ma8125499 - 19 Dec 2015

Cited by 27 | Viewed by 7255

Abstract

In this study, aligned zinc oxide (ZnO) nanorods (NRs) with various lengths (1.5–5 µm) were deposited on ZnO:Al (AZO)-coated glass substrates by using a solution phase deposition method; these NRs were prepared for application as working electrodes to increase the photovoltaic conversion efficiency [...] Read more.

In this study, aligned zinc oxide (ZnO) nanorods (NRs) with various lengths (1.5–5 µm) were deposited on ZnO:Al (AZO)-coated glass substrates by using a solution phase deposition method; these NRs were prepared for application as working electrodes to increase the photovoltaic conversion efficiency of solar cells. The results were observed in detail by using X-ray diffraction, field-emission scanning electron microscopy, UV-visible spectrophotometry, electrochemical impedance spectroscopy, incident photo-to-current conversion efficiency, and solar simulation. The results indicated that when the lengths of the ZnO NRs increased, the adsorption of D-719 dyes through the ZnO NRs increased along with enhancing the short-circuit photocurrent and open-circuit voltage of the cell. An optimal power conversion efficiency of 0.64% was obtained in a dye-sensitized solar cell (DSSC) containing the ZnO NR with a length of 5 µm. The objective of this study was to facilitate the development of a ZnO-based DSSC. Full article

(This article belongs to the Special Issue Photovoltaic Materials and Electronic Devices)

► Show Figures

Figure 1

4123 KiB

Open AccessArticle

Preparation and Compatibility Evaluation of Polypropylene/High Density Polyethylene Polyblends

by Jia-Horng Lin, Yi-Jun Pan, Chi-Fan Liu, Chien-Lin Huang, Chien-Teng Hsieh, Chih-Kuang Chen, Zheng-Ian Lin and Ching-Wen Lou

Materials 2015, 8(12), 8850-8859; https://doi.org/10.3390/ma8125496 - 17 Dec 2015

Cited by 108 | Viewed by 15408

Abstract

This study proposes melt-blending polypropylene (PP) and high density polyethylene (HDPE) that have a similar melt flow index (MFI) to form PP/HDPE polyblends. The influence of the content of HDPE on the properties and compatibility of polyblends is examined by using a tensile [...] Read more.

This study proposes melt-blending polypropylene (PP) and high density polyethylene (HDPE) that have a similar melt flow index (MFI) to form PP/HDPE polyblends. The influence of the content of HDPE on the properties and compatibility of polyblends is examined by using a tensile test, flexural test, Izod impact test, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), polarized light microscopy (PLM), and X-ray diffraction (XRD). The SEM results show that PP and HDPE are incompatible polymers with PP being a continuous phase and HDPE being a dispersed phase. The FTIR results show that the combination of HDPE does not influence the chemical structure of PP, indicating that the polyblends are made of a physical blending. The DSC and XRD results show that PP and HDPE are not compatible, and the combination of HDPE is not correlated with the crystalline structure and stability of PP. The PLM results show that the combination of HDPE causes stacking and incompatibility between HDPE and PP spherulites, and PP thus has incomplete spherulite morphology and a smaller spherulite size. However, according to mechanical property test results, the combination of HDPE improves the impact strength of PP. Full article

(This article belongs to the Special Issue Selected Papers from ICBEI2015)

► Show Figures

Figure 1

4057 KiB

Open AccessArticle

A Novel Approach of Using Ground CNTs as the Carbon Source to Fabricate Uniformly Distributed Nano-Sized TiC_x/2009Al Composites

by Lei Wang, Feng Qiu, Licheng Ouyang, Huiyuan Wang, Min Zha, Shili Shu, Qinglong Zhao and Qichuan Jiang

Materials 2015, 8(12), 8839-8849; https://doi.org/10.3390/ma8125495 - 17 Dec 2015

Cited by 21 | Viewed by 4895

Abstract

Nano-sized TiC_x/2009Al composites (with 5, 7, and 9 vol% TiC_x) were fabricated via the combustion synthesis of the 2009Al-Ti-CNTs system combined with vacuum hot pressing followed by hot extrusion. In the present study, CNTs were used as the carbon [...] Read more.

Nano-sized TiC_x/2009Al composites (with 5, 7, and 9 vol% TiC_x) were fabricated via the combustion synthesis of the 2009Al-Ti-CNTs system combined with vacuum hot pressing followed by hot extrusion. In the present study, CNTs were used as the carbon source to synthesize nano-sized TiC_x particles. An attempt was made to correlate the effect of ground CNTs by milling and the distribution of synthesized nano-sized TiC_x particles in 2009Al as well as the tensile properties of nano-sized TiC_x/2009Al composites. Microstructure analysis showed that when ground CNTs were used, the synthesized nano-sized TiC_x particles dispersed more uniformly in the 2009Al matrix. Moreover, when 2 h-milled CNTs were used, the 5, 7, and 9 vol% nano-sized TiC_x/2009Al composites had the highest tensile properties, especially, the 9 vol% nano-sized TiC_x/2009Al composites. The results offered a new approach to improve the distribution of in situ nano-sized TiC_x particles and tensile properties of composites. Full article

► Show Figures

Figure 1

6935 KiB

Open AccessArticle

Utilization of Palm Oil Clinker as Cement Replacement Material

by Jegathish Kanadasan and Hashim Abdul Razak

Materials 2015, 8(12), 8817-8838; https://doi.org/10.3390/ma8125494 - 16 Dec 2015

Cited by 51 | Viewed by 8628

Abstract

The utilization of waste materials from the palm oil industry provides immense benefit to various sectors of the construction industry. Palm oil clinker is a by-product from the processing stages of palm oil goods. Channelling this waste material into the building industry helps [...] Read more.

The utilization of waste materials from the palm oil industry provides immense benefit to various sectors of the construction industry. Palm oil clinker is a by-product from the processing stages of palm oil goods. Channelling this waste material into the building industry helps to promote sustainability besides overcoming waste disposal problems. Environmental pollution due to inappropriate waste management system can also be drastically reduced. In this study, cement was substituted with palm oil clinker powder as a binder material in self-compacting mortar. The fresh, hardened and microstructure properties were evaluated throughout this study. In addition, sustainability component analysis was also carried out to assess the environmental impact of introducing palm oil clinker powder as a replacement material for cement. It can be inferred that approximately 3.3% of cement production can be saved by substituting palm oil clinker powder with cement. Reducing the utilization of cement through a high substitution level of this waste material will also help to reduce carbon emissions by 52%. A cleaner environment free from pollutants can be created to ensure healthier living. Certain industries may benefit through the inclusion of this waste material as the cost and energy consumption of the product can be minimized. Full article

(This article belongs to the Special Issue Utilisation of By-Product Materials in Concrete)

► Show Figures

Figure 1

2436 KiB

Open AccessArticle

Improvement of Bearing Capacity in Recycled Aggregates Suitable for Use as Unbound Road Sub-Base

by Laura Garach, Mónica López, Francisco Agrela, Javier Ordóñez, Javier Alegre and José Antonio Moya

Materials 2015, 8(12), 8804-8816; https://doi.org/10.3390/ma8125493 - 16 Dec 2015

Cited by 21 | Viewed by 5206

Abstract

Recycled concrete aggregates and mixed recycled aggregates are specified as types of aggregates with lower densities, higher water absorption capacities, and lower mechanical strength than natural aggregates. In this paper, the mechanical behaviour and microstructural properties of natural aggregates, recycled concrete aggregates and [...] Read more.

Recycled concrete aggregates and mixed recycled aggregates are specified as types of aggregates with lower densities, higher water absorption capacities, and lower mechanical strength than natural aggregates. In this paper, the mechanical behaviour and microstructural properties of natural aggregates, recycled concrete aggregates and mixed recycled aggregates were compared. Different specimens of unbound recycled mixtures demonstrated increased resistance properties. The formation of new cement hydrated particles was observed, and pozzolanic reactions were discovered by electronon microscopy in these novel materials. The properties of recycled concrete aggregates and mixed recycled aggregates suggest that these recycled materials can be used in unbound road layers to improve their mechanical behaviour in the long term. Full article

(This article belongs to the Section Manufacturing Processes and Systems)

► Show Figures

Figure 1

681 KiB

Open AccessReview

Melt-Flow Behaviours of Thermoplastic Materials under Fire Conditions: Recent Experimental Studies and Some Theoretical Approaches

by Paul Joseph and Svetlana Tretsiakova-McNally

Materials 2015, 8(12), 8793-8803; https://doi.org/10.3390/ma8125492 - 15 Dec 2015

Cited by 24 | Viewed by 5204

Abstract

Polymeric materials often exhibit complex combustion behaviours encompassing several stages and involving solid phase, gas phase and interphase. A wide range of qualitative, semi-quantitative and quantitative testing techniques are currently available, both at the laboratory scale and for commercial purposes, for evaluating the [...] Read more.

Polymeric materials often exhibit complex combustion behaviours encompassing several stages and involving solid phase, gas phase and interphase. A wide range of qualitative, semi-quantitative and quantitative testing techniques are currently available, both at the laboratory scale and for commercial purposes, for evaluating the decomposition and combustion behaviours of polymeric materials. They include, but are not limited to, techniques such as: thermo-gravimetric analysis (TGA), oxygen bomb calorimetry, limiting oxygen index measurements (LOI), Underwriters Laboratory 94 (UL-94) tests, cone calorimetry, etc. However, none of the above mentioned techniques are capable of quantitatively deciphering the underpinning physiochemical processes leading to the melt flow behaviour of thermoplastics. Melt-flow of polymeric materials can constitute a serious secondary hazard in fire scenarios, for example, if they are present as component parts of a ceiling in an enclosure. In recent years, more quantitative attempts to measure the mass loss and melt-drip behaviour of some commercially important chain- and step-growth polymers have been accomplished. The present article focuses, primarily, on the experimental and some theoretical aspects of melt-flow behaviours of thermoplastics under heat/fire conditions. Full article

► Show Figures

Figure 1

2741 KiB

Open AccessArticle

Investigation on the Mechanical Properties of a Cement-Based Material Containing Carbon Nanotube under Drying and Freeze-Thaw Conditions

by Wei-Wen Li, Wei-Ming Ji, Yao-Cheng Wang, Yi Liu, Ruo-Xu Shen and Feng Xing

Materials 2015, 8(12), 8780-8792; https://doi.org/10.3390/ma8125491 - 14 Dec 2015

Cited by 92 | Viewed by 6735

Abstract

This paper aimed to explore the mechanical properties of a cement-based material with carbon nanotube (CNT) under drying and freeze-thaw environments. Mercury Intrusion Porosimetry and Scanning Electron Microscopy were used to analyze the pore structure and microstructure of CNT/cement composite, respectively. The experimental [...] Read more.

This paper aimed to explore the mechanical properties of a cement-based material with carbon nanotube (CNT) under drying and freeze-thaw environments. Mercury Intrusion Porosimetry and Scanning Electron Microscopy were used to analyze the pore structure and microstructure of CNT/cement composite, respectively. The experimental results showed that multi-walled CNT (MWCNT) could improve to different degrees the mechanical properties (compressive and flexural strengths) and physical performances (shrinkage and water loss) of cement-based materials under drying and freeze-thaw conditions. This paper also demonstrated that MWCNT could interconnect hydration products to enhance the performance of anti-microcracks for cement-based materials, as well as the density of materials due to CNT’s filling action. Full article

► Show Figures

Figure 1

7194 KiB

Open AccessArticle

Effect of Different Manufacturing Methods on the Conflict between Porosity and Mechanical Properties of Spiral and Porous Polyethylene Terephthalate/Sodium Alginate Bone Scaffolds

by Ching-Wen Lou, Chien-Lin Huang, Chih-Kuang Chen, Chi-Fan Liu, Shih-Peng Wen and Jia-Horng Lin

Materials 2015, 8(12), 8768-8779; https://doi.org/10.3390/ma8125488 - 14 Dec 2015

Cited by 7 | Viewed by 4982

Abstract

In order to solve the incompatibility between high porosity and mechanical properties, this study fabricates bone scaffolds by combining braids and sodium alginate (SA) membranes. Polyethylene terephthalate (PET) plied yarns are braided into hollow, porous three dimensional (3D) PET braids, which are then [...] Read more.

In order to solve the incompatibility between high porosity and mechanical properties, this study fabricates bone scaffolds by combining braids and sodium alginate (SA) membranes. Polyethylene terephthalate (PET) plied yarns are braided into hollow, porous three dimensional (3D) PET braids, which are then immersed in SA solution, followed by cross-linking with calcium chloride (CaCl₂) and drying, to form PET bone scaffolds. Next, SA membranes are rolled and then inserted into the braids to form the spiral and porous PET/SA bone scaffolds. Samples are finally evaluated for surface observation, porosity, water contact angle, compressive strength, and MTT assay. The test results show that the PET bone scaffolds and PET/SA bone scaffolds both have good hydrophilicity. An increasing number of layers and an increasing CaCl₂ concentration cause the messy, loose surface structure to become neat and compact, which, in turn, decreases the porosity and increases the compressive strength. The MTT assay results show that the cell viability of differing SA membranes is beyond 100%, indicating that the PET/SA bone scaffolds containing SA membranes are biocompatible for cell attachment and proliferation. Full article

(This article belongs to the Special Issue Selected Papers from ICBEI2015)

► Show Figures

Figure 1

5849 KiB

Open AccessArticle

Failure Progress of 3D Reinforced GFRP Laminate during Static Bending, Evaluated by Means of Acoustic Emission and Vibrations Analysis

by Mateusz Koziol and Tomasz Figlus

Materials 2015, 8(12), 8751-8767; https://doi.org/10.3390/ma8125490 - 14 Dec 2015

Cited by 8 | Viewed by 6321

Abstract

The work aimed to assess the failure progress in a glass fiber-reinforced polymer laminate with a 3D-woven and (as a comparison) plain-woven reinforcement, during static bending, using acoustic emission signals. The innovative method of the separation of the signal coming from the fiber [...] Read more.

The work aimed to assess the failure progress in a glass fiber-reinforced polymer laminate with a 3D-woven and (as a comparison) plain-woven reinforcement, during static bending, using acoustic emission signals. The innovative method of the separation of the signal coming from the fiber fracture and the one coming from the matrix fracture with the use of the acoustic event’s energy as a criterion was applied. The failure progress during static bending was alternatively analyzed by evaluation of the vibration signal. It gave a possibility to validate the results of the acoustic emission. Acoustic emission, as well as vibration signal analysis proved to be good and effective tools for the registration of failure effects in composite laminates. Vibration analysis is more complicated methodologically, yet it is more precise. The failure progress of the 3D laminate is “safer” and more beneficial than that of the plain-woven laminate. It exhibits less rapid load capacity drops and a higher fiber effort contribution at the moment of the main laminate failure. Full article

(This article belongs to the Special Issue Failure Analysis in Materials)

► Show Figures

Figure 1

3685 KiB

Open AccessCommunication

The ZrO₂ Formation in ZrB₂/SiC Composite Irradiated by Laser

by Ling Liu, Zhuang Ma, Zhenyu Yan, Shizhen Zhu and Lihong Gao

Materials 2015, 8(12), 8745-8750; https://doi.org/10.3390/ma8125475 - 14 Dec 2015

Cited by 16 | Viewed by 5265

Abstract

In order to clearly understand the details of ZrO₂ formation during ablation, high intensity continuous laser was chosen to irradiate ZrB₂/SiC. The results reveal that there are two different modes of ZrO₂ formation depending on whether liquid SiO₂ [...] Read more.

In order to clearly understand the details of ZrO₂ formation during ablation, high intensity continuous laser was chosen to irradiate ZrB₂/SiC. The results reveal that there are two different modes of ZrO₂ formation depending on whether liquid SiO₂ is present. When liquid SiO₂ is present, ZrO₂ generated by the oxidation of ZrB₂ is firstly dissolved into SiO₂. Then, ZrO₂ will precipitate again, the temperature will decrease and the SiO₂ will evaporate. Otherwise, the ZrB₂ will be oxidized to ZrO₂ directly. Full article

(This article belongs to the Section Advanced Composites)

► Show Figures

Figure 1

5718 KiB

Open AccessArticle

Experimental Characteristics of Dry Stack Masonry under Compression and Shear Loading

by Kun Lin, Yuri Zarevich Totoev, Hongjun Liu and Chunli Wei

Materials 2015, 8(12), 8731-8744; https://doi.org/10.3390/ma8125489 - 12 Dec 2015

Cited by 24 | Viewed by 5508

Abstract

The behavior of dry stack masonry (DSM) is influenced by the interaction of the infill with the frame (especially the joints between bricks), which requires further research. This study investigates the compression and shear behaviors of DSM. First, a series of compression tests [...] Read more.

The behavior of dry stack masonry (DSM) is influenced by the interaction of the infill with the frame (especially the joints between bricks), which requires further research. This study investigates the compression and shear behaviors of DSM. First, a series of compression tests were carried out on both masonry prism with mortar (MP_m) and DSM prism (MP_ds). The failure mode of each prism was determined. Different from the MP_m, the stress-strain relationship of the MP_ds was characterized by an upward concavity at the initial stage. The compression strength of the MP_ds was slightly reduced by 15%, while the elastic modulus was reduced by over 62%. In addition, 36 shear-compression tests were carried out under cyclic loads to emphasize the influence of various loads on the shear-compression behavior of DSM. The results showed that the Mohr-Coulomb friction law adequately represents the failure of dry joints at moderate stress levels, and the varying friction coefficients under different load amplitudes cannot be neglected. The experimental setup and results are valuable for further research. Full article

(This article belongs to the Section Advanced Materials Characterization)

► Show Figures

Figure 1

147 KiB

Open AccessCorrection

Correction: Electrochemical Investigation of the Corrosion of Different Microstructural Phases of X65 Pipeline Steel under Saturated Carbon Dioxide Conditions. Materials 2015, 8, 2635–2649

by Yuanfeng Yang, Gaurav R. Joshi and Robert Akid

Materials 2015, 8(12), 8728-8730; https://doi.org/10.3390/ma8125485 - 11 Dec 2015

Cited by 1 | Viewed by 3296

Abstract

In the published manuscript “Electrochemical Investigation of the Corrosion of Different Microstructural Phases of X65 Pipeline Steel under Saturated Carbon Dioxide Conditions. [...] Full article

519 KiB

Open AccessArticle

Prediction of the Chloride Resistance of Concrete Modified with High Calcium Fly Ash Using Machine Learning

by Michał Marks, Michał A. Glinicki and Karolina Gibas

Materials 2015, 8(12), 8714-8727; https://doi.org/10.3390/ma8125483 - 11 Dec 2015

Cited by 25 | Viewed by 5277

Abstract

The aim of the study was to generate rules for the prediction of the chloride resistance of concrete modified with high calcium fly ash using machine learning methods. The rapid chloride permeability test, according to the Nordtest Method Build 492, was used for [...] Read more.

The aim of the study was to generate rules for the prediction of the chloride resistance of concrete modified with high calcium fly ash using machine learning methods. The rapid chloride permeability test, according to the Nordtest Method Build 492, was used for determining the chloride ions’ penetration in concrete containing high calcium fly ash (HCFA) for partial replacement of Portland cement. The results of the performed tests were used as the training set to generate rules describing the relation between material composition and the chloride resistance. Multiple methods for rule generation were applied and compared. The rules generated by algorithm J48 from the Weka workbench provided the means for adequate classification of plain concretes and concretes modified with high calcium fly ash as materials of good, acceptable or unacceptable resistance to chloride penetration. Full article

(This article belongs to the Special Issue Utilisation of By-Product Materials in Concrete)

► Show Figures

Graphical abstract

2655 KiB

Open AccessArticle

Acid Denaturation Inducing Self-Assembly of Curcumin-Loaded Hemoglobin Nanoparticles

by Kaikai Wang, Juan Wang, Wenwen Hu, Yifan Zhang, Feng Zhi, Zaigang Zhou, Jinhui Wu and Yiqiao Hu

Materials 2015, 8(12), 8701-8713; https://doi.org/10.3390/ma8125486 - 11 Dec 2015

Cited by 14 | Viewed by 7343

Abstract

Hemoglobin is a promising drug carrier but lacks extensive investigation. The chemical conjugation of hemoglobin and drugs is costly and complex, so we have developed curcumin-loaded hemoglobin nanoparticles (CCM-Hb-NPs) via self-assembly for the first time. Using the acid-denaturing method, we avoid introducing denaturants [...] Read more.

Hemoglobin is a promising drug carrier but lacks extensive investigation. The chemical conjugation of hemoglobin and drugs is costly and complex, so we have developed curcumin-loaded hemoglobin nanoparticles (CCM-Hb-NPs) via self-assembly for the first time. Using the acid-denaturing method, we avoid introducing denaturants and organic solvents. The nanoparticles are stable with uniform size. We have conducted a series of experiments to examine the interaction of hemoglobin and CCM, including hydrophobic characterization, SDS-PAGE. These experiments substantiate that this self-assembly process is mainly driven by hydrophobic forces. Our nanoparticles achieve much higher cell uptake efficiency and cytotoxicity than free CCM solution in vitro. The uptake inhibition experiments also demonstrate that our nanoparticles were incorporated via the classic clathrin-mediated endocytosis pathway. These results indicate that hemoglobin nanoparticles formed by self-assembly are a promising drug delivery system for cancer therapy. Full article

(This article belongs to the Special Issue Materials and Nanomaterials for Environmental and Bio-Medical Applications)

► Show Figures

Figure 1

1979 KiB

Open AccessArticle

Properties of Cadmium-(bis)dodecylthiolate and Polymeric Composites Based on It

by Nadezhda Agareva, Anton A. Smirnov, Andrey Afanasiev, Semen Sologubov, Alexey Markin, Evgenia Salomatina, Larisa Smirnova and Nikita Bityurin

Materials 2015, 8(12), 8691-8700; https://doi.org/10.3390/ma8125487 - 11 Dec 2015

Cited by 11 | Viewed by 4084

Abstract

We study the thermo-physical and photoluminescence (PL) properties of cadmium-(bis)dodecylthiolate (Cd(C₁₂H₂₅S)₂). Significant attention is drawn to characterization of Cd(C₁₂H₂₅S)₂ by different methods. The laser-induced PLs of Cd(C₁₂H₂₅ [...] Read more.

We study the thermo-physical and photoluminescence (PL) properties of cadmium-(bis)dodecylthiolate (Cd(C₁₂H₂₅S)₂). Significant attention is drawn to characterization of Cd(C₁₂H₂₅S)₂ by different methods. The laser-induced PLs of Cd(C₁₂H₂₅S)₂ and Cd(C₁₂H₂₅S)₂/(polymethyl methacrylate) (PMMA) composites are studied. Samples of Cd(C₁₂H₂₅S)₂/PMMA are synthesized by the polymerization method. Ultraviolet (UV)-pulsed laser irradiation of the samples under relatively small fluences leads to the formation of induced PL with the maximum near the wavelength of 600 nm. This process can be attributed to the transformation of Cd(C₁₂H₂₅S)₂ within the precursor grains. Another PL peak at 450–500 nm, which appears under the higher fluences, relies on the formation of CdS complexes with a significant impact of the polymer matrix. Full article

(This article belongs to the Section Advanced Composites)

► Show Figures

Graphical abstract

5460 KiB

Open AccessReview

Graphene-Based Materials for Stem Cell Applications

by Tae-Hyung Kim, Taek Lee, Waleed A. El-Said and Jeong-Woo Choi

Materials 2015, 8(12), 8674-8690; https://doi.org/10.3390/ma8125481 - 11 Dec 2015

Cited by 64 | Viewed by 9373

Abstract

Although graphene and its derivatives have been proven to be suitable for several biomedical applications such as for cancer therapy and biosensing, the use of graphene for stem cell research is a relatively new area that has only recently started to be investigated. [...] Read more.

Although graphene and its derivatives have been proven to be suitable for several biomedical applications such as for cancer therapy and biosensing, the use of graphene for stem cell research is a relatively new area that has only recently started to be investigated. For stem cell applications, graphene has been utilized by itself or in combination with other types of materials such as nanoparticles, nanofibers, and polymer scaffolds to take advantage of the several unique properties of graphene, such as the flexibility in size, shape, hydrophilicity, as well as its excellent biocompatibility. In this review, we will highlight a number of previous studies that have investigated the potential of graphene or its derivatives for stem cell applications, with a particular focus on guiding stem cell differentiation into specific lineages (e.g., osteogenesis, neurogenesis, and oligodendrogenesis), promoting stem cell growth, stem cell delivery/transplantation, and effective monitoring of their differentiation. We hope that this review promotes and accelerates the use of graphene-based materials for regenerative therapies, especially for stem cell-based approaches to cure various incurable diseases/disorders such as neurological diseases (e.g., Alzheimer’s disease and Parkinson’s disease), stroke, spinal cord injuries, bone/cartilage defects, and cardiovascular diseases. Full article

(This article belongs to the Special Issue Graphene)

► Show Figures

Figure 1

6037 KiB

Open AccessArticle

A Photolithographic Approach to Polymeric Microneedles Array Fabrication

by Principia Dardano, Alessandro Caliò, Vincenza Di Palma, Maria Fortuna Bevilacqua, Andrea Di Matteo and Luca De Stefano

Materials 2015, 8(12), 8661-8673; https://doi.org/10.3390/ma8125484 - 11 Dec 2015

Cited by 64 | Viewed by 10168

Abstract

In this work, two procedures for fabrication of polymeric microneedles based on direct photolithography, without any etching or molding process, are reported. Polyethylene glycol (average molecular weight 250 Da), casted into a silicone vessel and exposed to ultraviolet light (365 nm) through a [...] Read more.

In this work, two procedures for fabrication of polymeric microneedles based on direct photolithography, without any etching or molding process, are reported. Polyethylene glycol (average molecular weight 250 Da), casted into a silicone vessel and exposed to ultraviolet light (365 nm) through a mask, cross-links when added by a commercial photocatalyzer. By changing the position of the microneedles support with respect to the vessel, different shapes and lengths can be achieved. Microneedles from a hundred microns up to two millimeters have been obtained just tuning the radiation dose, by changing the exposure time (5–15 s) and/or the power density (9–18 mW/cm²) during photolithography. Different microneedle shapes, such as cylindrical, conic or lancet-like, for specific applications such as micro-indentation or drug delivery, are demonstrated. Full article

(This article belongs to the Section Manufacturing Processes and Systems)

► Show Figures

Figure 1

18761 KiB

Open AccessArticle

High-Temperature Storage Testing of ACF Attached Sensor Structures

by Sanna Lahokallio, Maija Hoikkanen, Jyrki Vuorinen and Laura Frisk

Materials 2015, 8(12), 8641-8660; https://doi.org/10.3390/ma8125455 - 10 Dec 2015

Cited by 8 | Viewed by 6695

Abstract

Several electronic applications must withstand elevated temperatures during their lifetime. Materials and packages for use in high temperatures have been designed, but they are often very expensive, have limited compatibility with materials, structures, and processing techniques, and are less readily available than traditional [...] Read more.

Several electronic applications must withstand elevated temperatures during their lifetime. Materials and packages for use in high temperatures have been designed, but they are often very expensive, have limited compatibility with materials, structures, and processing techniques, and are less readily available than traditional materials. Thus, there is an increasing interest in using low-cost polymer materials in high temperature applications. This paper studies the performance and reliability of sensor structures attached with anisotropically conductive adhesive film (ACF) on two different organic printed circuit board (PCB) materials: FR-4 and Rogers. The test samples were aged at 200 °C and 240 °C and monitored electrically during the test. Material characterization techniques were also used to analyze the behavior of the materials. Rogers PCB was observed to be more stable at high temperatures in spite of degradation observed, especially during the first 120 h of aging. The electrical reliability was very good with Rogers. At 200 °C, the failures occurred after 2000 h of testing, and even at 240 °C the interconnections were functional for 400 h. The study indicates that, even though these ACFs were not designed for use in high temperatures, with stable PCB material they are promising interconnection materials at elevated temperatures, especially at 200 °C. However, the fragility of the structure due to material degradation may cause reliability problems in long-term high temperature exposure. Full article

► Show Figures

Figure 1

3120 KiB

Open AccessArticle

Synthesis and Characterization of Biopolymeric Chitosan Derived from Land Snail Shells and Its Potential for Pb2+ Removal from Aqueous Solution

by Joshua N. Edokpayi, John O. Odiyo, Elizabeth O. Popoola, Oluwagbemiga S. Alayande and Titus A. M. Msagati

Materials 2015, 8(12), 8630-8640; https://doi.org/10.3390/ma8125482 - 10 Dec 2015

Cited by 23 | Viewed by 5186

Abstract

Pb²⁺ is considered to be a very toxic pollutant in the aquatic environmental media. Biopolymeric chitosan synthesized from snail shell has been studied for its potential to remove heavy metals from aqueous solution. The experiments were conducted in the range of 1–50 [...] Read more.

Pb²⁺ is considered to be a very toxic pollutant in the aquatic environmental media. Biopolymeric chitosan synthesized from snail shell has been studied for its potential to remove heavy metals from aqueous solution. The experiments were conducted in the range of 1–50 mg/L initial Pb²⁺ concentration at 298 K. The effects of pH, adsorbent dosage and contact time on the adsorptive property of the adsorbent were investigated and optimized. The derived chitosan was characterized using Fourier transform infrared spectrometer (FT-IR) and X-ray florescence (XRF). The experimental data obtained were analysed using the Langmuir and Freundlich adsorption isotherm models. The Langmuir model and pseudo second order kinetic model suitably described the adsorption and kinetics of the process with regression coefficient of 0.99 and 1.00, respectively. Sodium hydroxide was a better desorbing agent than hydrochloric acid and de-ionized water. From the results obtained, it is concluded that synthesized biopolymers from land snail shells has the potential for the removal of Pb²⁺ from aqueous solutions. Full article

(This article belongs to the Section Biomaterials)

► Show Figures

Figure 1

918 KiB

Open AccessCommunication

Drastic Dependence of the pH Sensitivity of Fe₂O₃-Bi₂O₃-B₂O₃ Hydrophobic Glasses with Composition

by Tadanori Hashimoto, Fumiya Murayama, Masashi Nakao, Hiroyuki Nasu, Atsushi Ishihara and Yuji Nishio

Materials 2015, 8(12), 8624-8629; https://doi.org/10.3390/ma8125480 - 10 Dec 2015

Cited by 6 | Viewed by 4684

Abstract

Fe₂O₃-Bi₂O₃-B₂O₃ (FeBiB) glasses were developed as novel pH responsive hydrophobic glasses. The influence of the glass composition on the pH sensitivity of FeBiB glasses was investigated. The pH sensitivity drastically decreased with [...] Read more.

Fe₂O₃-Bi₂O₃-B₂O₃ (FeBiB) glasses were developed as novel pH responsive hydrophobic glasses. The influence of the glass composition on the pH sensitivity of FeBiB glasses was investigated. The pH sensitivity drastically decreased with decreasing B₂O₃ content. A moderate amount of Fe₂O₃ and a small amount of B₂O₃ respectively produces bulk electronic conduction and a pH response on glass surfaces. Because the remaining components of the glass can be selected freely, this discovery could prove very useful in developing novel pH glass electrodes that are self-cleaning and resist fouling. Full article

(This article belongs to the Special Issue Self-Cleaning and Antimicrobial Surfaces)

► Show Figures

Graphical abstract

1815 KiB

Open AccessArticle

Effects of Medium Temperature and Industrial By-Products on the Key Hardened Properties of High Performance Concrete

by Md. Safiuddin, Sudharshan N. Raman and Muhammad Fauzi Mohd. Zain

Materials 2015, 8(12), 8608-8623; https://doi.org/10.3390/ma8125464 - 10 Dec 2015

Cited by 7 | Viewed by 5157

Abstract

The aim of the work reported in this article was to investigate the effects of medium temperature and industrial by-products on the key hardened properties of high performance concrete. Four concrete mixes were prepared based on a water-to-binder ratio of 0.35. Two industrial [...] Read more.

The aim of the work reported in this article was to investigate the effects of medium temperature and industrial by-products on the key hardened properties of high performance concrete. Four concrete mixes were prepared based on a water-to-binder ratio of 0.35. Two industrial by-products, silica fume and Class F fly ash, were used separately and together with normal portland cement to produce three concrete mixes in addition to the control mix. The properties of both fresh and hardened concretes were examined in the laboratory. The freshly mixed concrete mixes were tested for slump, slump flow, and V-funnel flow. The hardened concretes were tested for compressive strength and dynamic modulus of elasticity after exposing to 20, 35 and 50 °C. In addition, the initial surface absorption and the rate of moisture movement into the concretes were determined at 20 °C. The performance of the concretes in the fresh state was excellent due to their superior deformability and good segregation resistance. In their hardened state, the highest levels of compressive strength and dynamic modulus of elasticity were produced by silica fume concrete. In addition, silica fume concrete showed the lowest level of initial surface absorption and the lowest rate of moisture movement into the interior of concrete. In comparison, the compressive strength, dynamic modulus of elasticity, initial surface absorption, and moisture movement rate of silica fume-fly ash concrete were close to those of silica fume concrete. Moreover, all concretes provided relatively low compressive strength and dynamic modulus of elasticity when they were exposed to 50 °C. However, the effect of increased temperature was less detrimental for silica fume and silica fume-fly ash concretes in comparison with the control concrete. Full article

(This article belongs to the Special Issue Utilisation of By-Product Materials in Concrete)

► Show Figures

Figure 1

1543 KiB

Open AccessReview

Recent Progress in Lectin-Based Biosensors

by Baozhen Wang and Jun-ichi Anzai

Materials 2015, 8(12), 8590-8607; https://doi.org/10.3390/ma8125478 - 09 Dec 2015

Cited by 43 | Viewed by 8173

Abstract

This article reviews recent progress in the development of lectin-based biosensors used for the determination of glucose, pathogenic bacteria and toxins, cancer cells, and lectins. Lectin proteins have been widely used for the construction of optical and electrochemical biosensors by exploiting the specific [...] Read more.

This article reviews recent progress in the development of lectin-based biosensors used for the determination of glucose, pathogenic bacteria and toxins, cancer cells, and lectins. Lectin proteins have been widely used for the construction of optical and electrochemical biosensors by exploiting the specific binding affinity to carbohydrates. Among lectin proteins, concanavalin A (Con A) is most frequently used for this purpose as glucose- and mannose-selective lectin. Con A is useful for immobilizing enzymes including glucose oxidase (GOx) and horseradish peroxidase (HRP) on the surface of a solid support to construct glucose and hydrogen peroxide sensors, because these enzymes are covered with intrinsic hydrocarbon chains. Con A-modified electrodes can be used as biosensors sensitive to glucose, cancer cells, and pathogenic bacteria covered with hydrocarbon chains. The target substrates are selectively adsorbed to the surface of Con A-modified electrodes through strong affinity of Con A to hydrocarbon chains. A recent topic in the development of lectin-based biosensors is a successful use of nanomaterials, such as metal nanoparticles and carbon nanotubes, for amplifying output signals of the sensors. In addition, lectin-based biosensors are useful for studying glycan expression on living cells. Full article

► Show Figures

Figure 1

1837 KiB

Open AccessArticle

Piezoelectric, Mechanical and Acoustic Properties of KNaNbOF₅ from First-Principles Calculations

by Han Han, Cheng Cheng, Xiao-Gen Xiong, Jing Su, Jian-Xing Dai, Hui Wang, Gen Yin and Ping Huai

Materials 2015, 8(12), 8578-8589; https://doi.org/10.3390/ma8125477 - 09 Dec 2015

Cited by 6 | Viewed by 5057

Abstract

Recently, a noncentrosymmetric crystal, KNaNbOF₅, has attracted attention due to its potential to present piezoelectric properties. Although α- and β-KNaNbOF₅ are similar in their stoichiometries, their structural frameworks, and their synthetic routes, the two phases exhibit very different properties. This [...] Read more.

Recently, a noncentrosymmetric crystal, KNaNbOF₅, has attracted attention due to its potential to present piezoelectric properties. Although α- and β-KNaNbOF₅ are similar in their stoichiometries, their structural frameworks, and their synthetic routes, the two phases exhibit very different properties. This paper presents, from first-principles calculations, comparative studies of the structural, electronic, piezoelectric, and elastic properties of the α and the β phase of the material. Based on the Christoffel equation, the slowness surface of the acoustic waves is obtained to describe its acoustic prosperities. These results may benefit further applications of KNaNbOF₅. Full article

(This article belongs to the Special Issue Piezoelectric Materials)

► Show Figures

Graphical abstract

7850 KiB

Open AccessArticle

The Corrosion Characteristics and Tensile Behavior of Reinforcement under Coupled Carbonation and Static Loading

by Yidong Xu

Materials 2015, 8(12), 8561-8577; https://doi.org/10.3390/ma8125479 - 09 Dec 2015

Cited by 11 | Viewed by 5124

Abstract

This paper describes the non-uniform corrosion characteristics and mechanical properties of reinforcement under coupled action of carbonation and static loading. The two parameters, namely area-box (AB) value and arithmetical mean deviation (R_a), are adopted to characterize the corrosion morphology and [...] Read more.

This paper describes the non-uniform corrosion characteristics and mechanical properties of reinforcement under coupled action of carbonation and static loading. The two parameters, namely area-box (AB) value and arithmetical mean deviation (R_a), are adopted to characterize the corrosion morphology and pitting distribution from experimental observations. The results show that the static loading affects the corrosion characteristics of reinforcement. Local stress concentration in corroded reinforcement caused by tensile stress drives the corrosion pit pattern to be more irregular. The orthogonal test results from finite element simulations show that pit shape and pit depth are the two significant factors affecting the tensile behavior of reinforcement. Under the condition of similar corrosion mass loss ratio, the maximum plastic strain of corroded reinforcement increases with the increase of R_a and load time-history significantly. Full article

► Show Figures

Figure 1

19009 KiB

Open AccessArticle

Damage Evolution and Life Prediction of Cross-Ply C/SiC Ceramic-Matrix Composite under Cyclic Fatigue Loading at Room Temperature and 800 °C in Air

by Longbiao Li

Materials 2015, 8(12), 8539-8560; https://doi.org/10.3390/ma8125474 - 09 Dec 2015

Cited by 16 | Viewed by 4683

Abstract

The damage evolution and life prediction of cross-ply C/SiC ceramic-matrix composite (CMC) under cyclic-fatigue loading at room temperature and 800 °C in air have been investigated using damage parameters derived from fatigue hysteresis loops, i.e., fatigue hysteresis modulus and fatigue hysteresis loss [...] Read more.

The damage evolution and life prediction of cross-ply C/SiC ceramic-matrix composite (CMC) under cyclic-fatigue loading at room temperature and 800 °C in air have been investigated using damage parameters derived from fatigue hysteresis loops, i.e., fatigue hysteresis modulus and fatigue hysteresis loss energy. The experimental fatigue hysteresis modulus and fatigue hysteresis loss energy degrade with increasing applied cycles attributed to transverse cracks in the 90° plies, matrix cracks and fiber/matrix interface debonding in the 0° plies, interface wear at room temperature, and interface and carbon fibers oxidation at 800 °C in air. The relationships between fatigue hysteresis loops, fatigue hysteresis modulus and fatigue hysteresis loss energy have been established. Comparing experimental fatigue hysteresis loss energy with theoretical computational values, the fiber/matrix interface shear stress corresponding to different cycle numbers has been estimated. It was found that the degradation rate at 800 °C in air is much faster than that at room temperature due to serious oxidation in the pyrolytic carbon (PyC) interphase and carbon fibers. Combining the fiber fracture model with the interface shear stress degradation model and the fibers strength degradation model, the fraction of broken fibers versus the cycle number can be determined for different fatigue peak stresses. The fatigue life S-N curves of cross-ply C/SiC composite at room temperature and 800 °C in air have been predicted. Full article

(This article belongs to the Section Advanced Composites)

► Show Figures

Figure 1

5276 KiB

Open AccessArticle

Process Design of Aluminum Tailor Heat Treated Blanks

by Alexander Kahrimanidis, Michael Lechner, Julia Degner, Daniel Wortberg and Marion Merklein

Materials 2015, 8(12), 8524-8538; https://doi.org/10.3390/ma8125476 - 09 Dec 2015

Cited by 19 | Viewed by 8298

Abstract

In many industrials field, especially in the automotive sector, there is a trend toward lightweight constructions in order to reduce the weight and thereby the CO₂ and NO_x emissions of the products. An auspicious approach within this context is the substitution [...] Read more.

In many industrials field, especially in the automotive sector, there is a trend toward lightweight constructions in order to reduce the weight and thereby the CO₂ and NO_x emissions of the products. An auspicious approach within this context is the substitution of conventional deep drawing steel by precipitation hardenable aluminum alloys. However, based on the low formability, the application for complex stamping parts is challenging. Therefore, at the Institute of Manufacturing Technology, an innovative technology to enhance the forming limit of these lightweight materials was invented. The key idea of the so-called Tailor Heat Treated Blanks (THTB) is optimization of the mechanical properties by local heat treatment before the forming operation. An accurate description of material properties is crucial to predict the forming behavior of tailor heat treated blanks by simulation. Therefore, within in this research project, a holistic approach for the design of the THTB process in dependency of the main influencing parameters is presented and discussed in detail. The capability of the approach for the process development of complex forming operations is demonstrated by a comparison of local blank thickness of a tailgate with the corresponding results from simulation. Full article

(This article belongs to the Special Issue Forming of Light Weight Materials)

► Show Figures

Figure 1

3187 KiB

Open AccessArticle

Effect of Hybrid Talc-Basalt Fillers in the Shell Layer on Thermal and Mechanical Performance of Co-Extruded Wood Plastic Composites

by Runzhou Huang, Changtong Mei, Xinwu Xu, Timo Kärki, Sunyoung Lee and Qinglin Wu

Materials 2015, 8(12), 8510-8523; https://doi.org/10.3390/ma8125473 - 08 Dec 2015

Cited by 31 | Viewed by 6442

Abstract

Hybrid basalt fiber (BF) and Talc filled high density polyethylene (HDPE) and co-extruded wood-plastic composites (WPCs) with different BF/Talc/HDPE composition levels in the shell were prepared and their mechanical, morphological and thermal properties were characterized. Incorporating BFs into the HDPE-Talc composite substantially enhanced [...] Read more.

Hybrid basalt fiber (BF) and Talc filled high density polyethylene (HDPE) and co-extruded wood-plastic composites (WPCs) with different BF/Talc/HDPE composition levels in the shell were prepared and their mechanical, morphological and thermal properties were characterized. Incorporating BFs into the HDPE-Talc composite substantially enhanced the thermal expansion property, flexural, tensile and dynamic modulus without causing a significant decrease in the tensile and impact strength of the composites. Strain energy estimation suggested positive and better interfacial interactions of HDPE with BFs than that with talc. The co-extruded structure design improved the mechanical properties of WPC due to the protective shell layer. The composite flexural and impact strength properties increased, and the thermal expansion decreased as BF content increased in the hybrid BF/Talc filled shells. The cone calorimetry data demonstrated that flame resistance of co-extruded WPCs was improved with the use of combined fillers in the shell layer, especially with increased loading of BFs. The combined shell filler system with BFs and Talc could offer a balance between cost and performance for co-extruded WPCs. Full article

(This article belongs to the Special Issue Bio- and Natural-Fiber Composites)

► Show Figures

Graphical abstract

1527 KiB

Open AccessArticle

Polyols from Microwave Liquefied Bagasse and Its Application to Rigid Polyurethane Foam

by Jiulong Xie, Xianglin Zhai, Chung Yun Hse, Todd F. Shupe and Hui Pan

Materials 2015, 8(12), 8496-8509; https://doi.org/10.3390/ma8125472 - 08 Dec 2015

Cited by 21 | Viewed by 6275

Abstract

Bagasse flour (BF) was liquefied using bi-component polyhydric alcohol (PA) as a solvent and phosphoric acid as a catalyst in a microwave reactor. The effect of BF to solvent ratio and reaction temperatures on the liquefaction extent and characteristics of liquefied products were [...] Read more.

Bagasse flour (BF) was liquefied using bi-component polyhydric alcohol (PA) as a solvent and phosphoric acid as a catalyst in a microwave reactor. The effect of BF to solvent ratio and reaction temperatures on the liquefaction extent and characteristics of liquefied products were evaluated. The results revealed that almost 75% of the raw bagasse was converted into liquid products within 9 min at 150 °C with a BF to solvent ratio of 1/4. The hydroxyl and acid values of the liquefied bagasse (LB) varied with the liquefied conditions. High reaction temperature combining with low BF to solvent ratio resulted in a low hydroxyl number for the LB. The molecular weight and polydispersity of the LB from reactions of 150 °C was lower compared to that from 125 °C. Rigid polyurethane (PU) foams were prepared from LB and methylene diphenyl diisocyanate (MDI), and the structural, mechanical and thermal properties of the PU foam were evaluated. The PU foams prepared using the LB from high reaction temperature showed better physical and mechanical performance in comparison to those from low reaction temperature. The amount of PA in the LB has the ability of increasing thermal stability of LB-PU foams. The results in this study may provide fundamental information on integrated utilizations of sugarcane bagasse via microwave liquefaction process. Full article

(This article belongs to the Special Issue Advances in Renewable Energy Conversion Materials)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Materials, Volume 8, Issue 12 (December 2015) – 63 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI