Journal of Nanomaterials The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Preparation and Characterization of Nanofibrous Polymer Scaffolds for Cartilage Tissue Engineering Thu, 22 Jan 2015 13:26:28 +0000 Polymer substrates obtained from poly(lactic acid) (PLA) nanofibres modified with carbon nanotubes (CNTs) and gelatin (GEL) for cartilage tissue engineering are studied. The work presents the results of physical, mechanical, and biological assessment. The hybrid structure of PLA and gelatine nanofibres, carbon nanotubes- (CNTs-) modified PLA nanofibres, and pure PLA-based nanofibres was manufactured in the form of fibrous membranes. The fibrous samples with different microstructures were obtained by electrospinning method. Microstructure, physical and mechanical properties of samples made from pure PLA nanofibres, CNTs-, and gelatin-modified PLA-nanofibres were studied. The scaffolds were also tested in vitro in cell culture of human chondrocytes collected from patients. To assess the influence of the nanofibrous scaffolds upon chondrocytes, tests for cytotoxicity and genotoxicity were performed. The work reveals that the nanofibrous structures studied were neither genotoxic nor cytotoxic, and their microstructure, physical and mechanical properties create promising scaffolds for potential use in cartilage repairing. Jarosław Markowski, Anna Magiera, Marta Lesiuk, Aleksander L. Sieron, Jan Pilch, and Stanislaw Blazewicz Copyright © 2015 Jarosław Markowski et al. All rights reserved. Effect of CdS/Mg-Doped CdSe Cosensitized Photoanode on Quantum Dot Solar Cells Thu, 22 Jan 2015 08:55:47 +0000 Quantum dots have emerged as a material platform for low-cost high-performance sensitized solar cells. And doping is an effective method to improve the performance of quantum dot sensitized solar cells (QDSSCs). Since Kwak et al. from South Korea proved the incorporation of Mg in the CdSe quantum dots (QDs) in 2007, the Mg-doped CdSe QDs have been thoroughly studied. Here we report a new attempt on CdS/Mg-doped CdSe quantum dot cosensitized solar cells (QDCSSC). We analyzed the performance of CdS/Mg-doped CdSe quantum dot cosensitized solar cells via discussing the different doping concentration of Mg and the different SILAR cycles of CdS. And we studied the mechanism of CdS/Mg-doped CdSe QDs in detail for the reason why the energy conversion efficiency had been promoted. It is a significant instruction on the development of Mg-doped CdSe quantum dot sensitized solar cells (QDSSCs). Yingxiang Guan, Xiaoping Zou, and Sheng He Copyright © 2015 Yingxiang Guan et al. All rights reserved. Synthesis of Boron Nanowires, Nanotubes, and Nanosheets Thu, 22 Jan 2015 08:02:11 +0000 The synthesis of boron nanowires, nanotubes, and nanosheets using a thermal vapor deposition process is reported. This work confirms previous research and provides a new method capable of synthesizing boron nanomaterials. The materials were made by using various combinations of MgB2, Mg(BH4)2, MCM-41, NiB, and Fe wire. Unlike previously reported methods, a nanoparticle catalyst and a silicate substrate are not required for synthesis. Two types of boron nanowires, boron nanotubes, and boron nanosheets were made. Their morphology and chemical composition were determined through the use of scanning electron microscopy, transmission electron microscopy, and electron energy loss spectroscopy. These boron-based materials have potential for electronic and hydrogen storage applications. Rajen B. Patel, Tsengming Chou, and Zafar Iqbal Copyright © 2015 Rajen B. Patel et al. All rights reserved. Photoinduced Electron Spin Resonance Phenomenon in α-Cr2O3 Nanospheres Wed, 21 Jan 2015 06:27:05 +0000 The photoinduced phenomenon in α-Cr2O3 nanoscaled spherical particles was investigated in the temperature range of 150 up to 315 K. An X-band electron-spin resonance spectrometry was employed to probe the magnetic behavior in α-Cr2O3 under an IR illumination in the nanosecond regime. The photoinduced effect on both low and high field ESR signals appears above 280 K and is remarkably enhanced just below Néel temperature . Such a photoinduced ESR phenomenon disappears in a reproducible way in the paramagnetic insulating state which occurs above of crystalline α-Cr2O3. In the antiferromagnetic phase, that is, below , the shift of the low field absorption could be attributed to the interaction of the light with specific Cr3+ ions located in strongly distorted sites correlated to strong ligand-field effect. S. Khamlich, V. V. Srinivasu, A. Konkin, N. Cingo, F. T. Thema, A. Benyoussef, and M. Maaza Copyright © 2015 S. Khamlich et al. All rights reserved. Enhanced Efficiency of Dye-Sensitized Solar Cells by Trace Amount Ca-Doping in TiO2 Photoelectrodes Tue, 20 Jan 2015 13:43:29 +0000 Trace amount Ca-doped TiO2 films were synthesized by the hydrothermal method and applied as photoanodes of dye-sensitized solar cells (DSSCs). To prepare Ca-doped TiO2 film electrodes, several milliliters of Ca(NO3)2 solution was added in TiO2 solution during the hydrolysis process. The improvements of DSSCs were confirmed by photocurrent density-voltage (J-V) characteristics, electrochemical impedance spectroscopy (EIS) measurements. Owing to the doping effect of Ca, the Ca-doped TiO2 thin film shows power conversion efficiency of 7.45% for 50 ppm Ca-doped TiO2 electrode, which is higher than that of the undoped TiO2 film (6.78%) and the short-circuit photocurrent density increases from 13.68 to 15.42 mA·cm−2. The energy conversion efficiency and short-circuit current density of DSSCs were increased due to the faster electron transport in the Ca-doped TiO2 film. When Ca was incorporated into TiO2 films, the electrons transport faster and the charge collection efficiency is higher than that in the undoped TiO2 films. Mengmei Pan, Hanjun Liu, Zhongyu Yao, and Xiaoli Zhong Copyright © 2015 Mengmei Pan et al. All rights reserved. Preparation and Evaluation of PEGylated and Folate-PEGylated Liposomes Containing Paclitaxel for Lymphatic Delivery Tue, 20 Jan 2015 13:10:42 +0000 This study attempted to prepare polyethylene-glycol modified (PEGylated) and folate-PEGylated liposomes containing paclitaxel (Ptx) in order to reduce the toxicity and improve the bioavailability and biocompatibility by targeting drugs to the lymphatics using cancer cell specific ligand folate to prevent metastasis via the lymphatic system. Liposomes were prepared by lipid film hydration method using PEG and folate-PEG as surface modifiers. The mean particle size and encapsulation efficiency of liposomes were  nm and % for PEGylated liposome and  nm and % for folate-PEGylated liposome, respectively. According to stability test, it could be confirmed that PEGylated and folate-PEGylated liposomes were stable for at least 5 days. After intravenous administration of the PEGylated and folate-PEGylated liposomes to rats, the (total clearance) and (half-life) were significantly different () compared with those of PADEXOL Inj. In targeting efficiency, calculated as the concentration ratio of Ptx in lymph nodes and plasma, there was significant increase in targeting efficiency at lymph nodes (). From these results, we could conclude that the prepared Ptx-containing PEGylated and folate-PEGylated liposomes are good candidates for the targeted delivery of the drug to lymphatic system. Hea-Young Cho, Chong Ki Lee, and Yong-Bok Lee Copyright © 2015 Hea-Young Cho et al. All rights reserved. High Performance Indium-Doped ZnO Gas Sensor Tue, 20 Jan 2015 10:28:01 +0000 Gas sensors for ethanol and acetone based on ZnO nanobelts with doping element indium were fabricated. Excellent sensitivity accompanied with short response time (10 s) and recovery time (23 s) to 150 ppm ethanol is obtained. For In-doped sensors, a minimum concentration of 37.5 ppm at 275°C in acetone was observed with an average sensitivity of 714.4, which is 7 times larger than that of the pure sensors and much larger than that reported response (16) of Co-doped ZnO nanofibers to acetone. These results indicate that doping elements can improve gas sensitivity, which is associated with oxygen space and valence ions. In-doped ZnO nanobelts exhibit higher sensitivity to acetone than that to ethanol. These results indicate that doped ZnO nanobelts can successfully distinguish acetone and ethanol, which can be put into various practical applications. Junjie Qi, Hong Zhang, Shengnan Lu, Xin Li, Minxuan Xu, and Yue Zhang Copyright © 2015 Junjie Qi et al. All rights reserved. In Situ Synthesis and Characterization of Polyethyleneimine-Modified Carbon Nanotubes Supported PtRu Electrocatalyst for Methanol Oxidation Mon, 19 Jan 2015 12:20:52 +0000 PtRu bimetallic nanoparticles were successfully synthesized on polyethyleneimine- (PEI-) functionalized multiwalled carbon nanotubes (MWCNTs) via an effective and facile polyol reduction approach. Noncovalent surface modification of MWCNTs with PEI was confirmed by FTIR and zeta potential measurements. The morphology, crystalline structure, and composition of the hybrid material were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and energy dispersive X-ray spectroscopy (EDX), respectively. According to SEM and TEM observations, PtRu nanoparticles with narrow size distribution were homogeneously deposited on PEI-MWCNTs. Cyclic voltammetry tests demonstrated that the as-prepared PtRu/PEI-MWCNTs nanocomposite had a large electrochemical surface area and exhibited enhanced electrocatalytic activity towards methanol oxidation in comparison with oxidized MWCNTs as catalyst support. PEI-functionalized CNTs, as useful building blocks for the assembly of Pt-based electrocatalyst, may have great potential for applications such as direct methanol fuel cell (DMFC). Xi Geng, Jieying Jing, Yinjie Cen, Ravindra Datta, and Jianyu Liang Copyright © 2015 Xi Geng et al. All rights reserved. Synthesis Method Effect of CoFe2O4 on Its Photocatalytic Properties for H2 Production from Water and Visible Light Sun, 18 Jan 2015 14:34:45 +0000 Currently, the need for more efficient materials that work in the visible light spectrum for hydrogen production has been increasing. Under this criterion, ferrites are ideal because their energetic properties are favorable to photocatalysis as they have a low band gap (1.5 to 3 ev). In this particular research, ferrite is presented as a hydrogen producer. Cobalt ferrites were synthesized by chemical coprecipitation (CP) and ball milling (BM) for comparison of their performance. The characterization of the materials was carried out with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET surface area, UV-VIS spectroscopy, and water adsorption/desorption tests. Evaluation of the photocatalytic activity under visible light was followed by gas chromatography. The results showed that cobalt ferrite by ball milling had a higher photocatalytic activity; this is attributed to the vacancies generated during the milling process at which the sample was exposed. Yudith Ortega López, Hugo Medina Vázquez, Jesús Salinas Gutiérrez, Vanessa Guzmán Velderrain, Alejandro López Ortiz, and Virginia Collins Martínez Copyright © 2015 Yudith Ortega López et al. All rights reserved. Estimating Young’s Modulus of Single-Walled Zirconia Nanotubes Using Nonlinear Finite Element Modeling Sun, 18 Jan 2015 13:57:06 +0000 The single-walled zirconia nanotube is structurally modeled and its Young’s modulus is valued by using the finite element approach. The nanotube was assumed to be a frame-like structure with bonds between atoms regarded as beam elements. The properties of the beam required for input into the finite element analysis were computed by connecting energy equivalence between molecular and continuum mechanics. Simulation was conducted by applying axial tensile strain on one end of the nanotube while the other end was fixed and the corresponding reaction force recorded to compute Young’s modulus. It was found out that Young’s modulus of zirconia nanotubes is significantly affected by some geometrical parameters such as chirality, diameter, thickness, and length. The obtained values of Young’s modulus for a certain range of diameters are in agreement with what was obtained in the few experiments that have been conducted so far. This study was conducted on the cubic phase of zirconia having armchair and zigzag configuration. The optimal diameter and thickness were obtained, which will assist in designing and fabricating bulk nanostructured components containing zirconia nanotubes for various applications. Ibrahim Dauda Muhammad, Mokhtar Awang, Othman Mamat, and Ku Zilati Ku Shaari Copyright © 2015 Ibrahim Dauda Muhammad et al. All rights reserved. Nanostructured Polylactic Acid/Candeia Essential Oil Mats Obtained by Electrospinning Thu, 15 Jan 2015 11:42:45 +0000 This work aims to evaluate the effect of inclusion of different contents of candeia (Eremanthus erythropappus) essential oil (whose alpha-bisabolol is the main terpene) on the properties of polylactic acid (PLA) nanostructured mats and their relationship with fiber morphology and structure. The interaction occurring between the PLA and the candeia essential oil was confirmed by thermal and microscopy analysis. Addition of candeia essential oil increased nanofiber diameter and decreased the glass transition and melting temperatures of the nanofibers, suggesting lower energy input for processing. Scanning electron microscopy (SEM) images provided evidence of a homogeneous structure for the nanostructured mats. X-ray diffraction did not show differences in the crystallization of the nanofibers. This ongoing research confirms the possibility of incorporation of candeia essential oil in the production of nanofibers that will be studied for multipurpose applications. Cláudia L. S. de Oliveira Mori, Nathália Almeida dos Passos, Juliano Elvis Oliveira, Thiza Falqueto Altoé, Fábio Akira Mori, Luiz Henrique Capparelli Mattoso, José Roberto Scolforo, and Gustavo Henrique Denzin Tonoli Copyright © 2015 Cláudia L. S. de Oliveira Mori et al. All rights reserved. Visible Light-Assisted Photoreduction of Graphene Oxide Using CdS Nanoparticles and Gas Sensing Properties Tue, 13 Jan 2015 06:52:24 +0000 Graphene oxide sheets suspended in ethanol interact with excited CdS nanoparticles and contributed to photocatalytic reduction by accepting electron from nanoparticle. The UV-Vis measurement showed that electrical absorbance of the CdS/graphene oxide sheets increased by decreasing the irradiation time and after 2 h it remained constant which indicates the optimum reduction time. Furthermore, the direct interaction between CdS nanoparticles and graphene sheets hinders the collapse of exfoliated sheets of graphene. The 4-point probe measurement of nanocomposite with different ratios of graphene oxide in CdS solution after irradiation shows that the conductivity of them increased by increasing the amount of GO, but further increasing causes incomplete photo reduction process due to exorbitance increasing GO sheets which contribute to decreasing the conductivity. The CdS/RGO composite material can be used as a gas sensor for CO2 based on its electrocatalytic behavior. The low-cost and easy fabrication sensor shows rapid response and high sensitivity. By varying the amount of GO the optimum concentration which shows high sensitivity is found and its good performance compared with other is attributed to its higher conductivity due to complete reduction. Moreover, the effects of thermal annealing on the conductivity of CdS/RGO film and the performance of devices are researched. Amirhossein Hasani, Hamed Sharifi Dehsari, Ali Amiri Zarandi, Alireza Salehi, Faramarz Afshar Taromi, and Hanif Kazeroni Copyright © 2015 Amirhossein Hasani et al. All rights reserved. Physical Properties of ZnO Thin Films Codoped with Titanium and Hydrogen Prepared by RF Magnetron Sputtering with Different Substrate Temperatures Tue, 13 Jan 2015 06:36:57 +0000 Transparent conducting titanium-doped zinc oxide (TZO) thin films were prepared on glass substrates by RF magnetron sputtering using 1.5 wt% TiO2-doped ZnO as the target. Electrical, structural, and optical properties of films were investigated as a function of H2/(Ar + H2) flow ratios () and substrate temperatures (). The optimal value for achieving high conducting TZO:H thin film decreased from 10% to 1% when increased from RT to 300°C. The lowest resistivity of  Ω-cm was obtained as °C and %. X-ray diffraction patterns showed that all of TZO:H films had a hexagonal wurtzite structure with a preferred orientation in the (002) direction. Atomic force microscopy analysis revealed that the film surface roughness increased with increasing . The average visible transmittance decreased with increasing for the RT-deposited film, while it had not considerably changed with different for the 300°C-deposited films. The optical bandgap increased as increased, which is consistent with the Burstein-Moss effect. The figure of merits indicated that °C and % were optimal conditions for TZO thin films as transparent conducting electrode applications. Fang-Hsing Wang, Jen-Chi Chao, Han-Wen Liu, and Tsung-Kuei Kang Copyright © 2015 Fang-Hsing Wang et al. All rights reserved. Effect of Synthesis Temperature, Nucleation Time, and Postsynthesis Heat Treatment of ZnO Nanoparticles and Its Sensing Properties Mon, 12 Jan 2015 08:32:42 +0000 Control in size, crystallinity, and optical properties of ZnO nanoparticles (NPs) synthesized via coprecipitate method were investigated. A systematic change in particle size, crystallinity, and optical properties was observed by increasing synthesis temperature from 65°C to 75°C. A detailed study also suggested that smaller nucleation time is better to control the size distribution but the crystallinity will be compromised accordingly. Postannealing of ZnO NPs at 400°C also improves the crystal quality. Ultraviolet (UV) sensors were successfully synthesized and the results suggested that as-synthesized ZnO NPs can be used as active material for sensor applications. Umair Manzoor, Fatima Tuz Zahra, Sidra Rafique, Muhammad Tahir Moin, and Mohammad Mujahid Copyright © 2015 Umair Manzoor et al. All rights reserved. Transition Metal Ion Implantation into Diamond-Like Carbon Coatings: Development of a Base Material for Gas Sensing Applications Mon, 12 Jan 2015 06:30:08 +0000 Micrometre thick diamond-like carbon (DLC) coatings produced by direct ion deposition were implanted with 30 keV Ar+ and transition metal ions in the lower percentage (<10 at.%) range. Theoretical calculations showed that the ions are implanted just beneath the surface, which was confirmed with RBS measurements. Atomic force microscope scans revealed that the surface roughness increases when implanted with Ar+ and Cu+ ions, whereas a smoothing of the surface from 5.2 to 2.7 nm and a grain size reduction from 175 to 93 nm are measured for Ag+ implanted coatings with a fluence of  at. cm−2. Calculated hydrogen and carbon depth profiles showed surprisingly significant changes in concentrations in the near-surface region of the DLC coatings, particularly when implanted with Ag+ ions. Hydrogen accumulates up to 32 at.% and the minimum of the carbon distribution is shifted towards the surface which may be the cause of the surface smoothing effect. The ion implantations caused an increase in electrical conductivity of the DLC coatings, which is important for the development of solid-state gas sensors based on DLC coatings. Andreas Markwitz, Jérôme Leveneur, Prasanth Gupta, Konrad Suschke, John Futter, and Morgane Rondeau Copyright © 2015 Andreas Markwitz et al. All rights reserved. Development of Polymer Based Nanocomposites as a Marker of Cadmium in Complex Matrices Sun, 11 Jan 2015 08:11:55 +0000 Poly(propylene carbonate)/β-cyclodextrin (PPC-BCD) nanocomposites were developed as effective extractor for a specific extraction and separation of cadmium(II) by use of inductively coupled plasma-optical emission spectrometry. The selectivity of nanocomposites with different wt% of BCD (PPC-BCD 0.5, PPC-BCD 1, PPC-BCD 3, PPC-BCD 5, or PPC-BCD 10) was investigated toward Cd(II). Based on selectivity and pH studies, Cd(II) was the most quantitatively adsorbed on PPC-BCD 5 phase at pH 6, indicating that PPC-BCD 5 was the most selective toward Cd(II) among other nanocomposites. On the basis of adsorption isotherm study, the superior adsorption capacity of PPC-BCD 5 phase for Cd(II) was found to be 149.25 mg·g−1, following the Langmuir adsorption isotherm model. The kinetic of adsorption for Cd(II) has been examined by pseudo-first- and second-order models. The kinetic exploration suggested a pseudo-second-order kinetic model for the adsorption of Cd(II) on the PPC-BCD 5. Additionally, results of thermodynamic investigation demonstrated favorable spontaneous process for the adsorption mechanism of PPC-BCD 5 toward Cd(II). Abdullah M. Asiri, Kalsoom Akhtar, Jongchul Seo, Hadi M. Marwani, Dowan Kim, Haksoo Han, and Sher Bahadar Khan Copyright © 2015 Abdullah M. Asiri et al. All rights reserved. The Photocatalytic Activity of TiO2-Zeolite Composite for Degradation of Dye Using Synthetic UV and Jeddah Sunlight Sun, 11 Jan 2015 06:12:36 +0000 In this research different composites of impregnated TiO2 with LTA or FAU zeolites were used as different weight% ratio for photodegradation of organic dye. Normal laboratory UV-lamps were used as a source of UV irradiation. In addition a setup of system of mirrors was used to collect real Jeddah sunlight. A comparison of UV and real sunlight photodegradation activity showed that the real sunlight enhances new centers of active sites exhibiting higher catalytic activity than that of UV irradiated samples. Laila M. Al-Harbi, Samia A. Kosa, Islam H. Abd El Maksod, and Eman Z. Hegazy Copyright © 2015 Laila M. Al-Harbi et al. All rights reserved. MnF2/SiO2 Transport Properties of Quasiperiodic Photonic Crystals for Potential Catalytic Applications Tue, 06 Jan 2015 08:38:55 +0000 Magnetically recyclable materials should be ideal support in photocatalytic system because they permit the photocatalysts to be recovered rapidly and efficiently by applying an external magnetic field such as, MnF2. In this paper, MnF2 and SiO2 layers constitute a one-dimensional quasiperiodic photonic crystal according to Fibonacci. When the electromagnetic wave irradiates obliquely, the transmission peak moves to higher frequency direction with the angle increasing. Both the number of transmission peaks and the transmission peaks of double-forked structure increase with the increase of structural progression. We also found that the polarization of electromagnetic waves has influence on the transmission properties; TM wave transmission peak half wide is significantly greater than TE wave transmission peak half wide. The band gap near antiferromagnetic (AF) resonance frequency becomes narrow as the intensity of the applied static magnetic field increases. The as-prepared photonic crystal has tremendous potential practical use to eliminate organic pollutants from wastewater. Qiang Zhang, Xuan-Zhang Wang, Shu-Fang Fu, Jing Bai, and Sheng Zhou Copyright © 2015 Qiang Zhang et al. All rights reserved. Wettability Investigation of UV/O3 and Acid Functionalized MWCNT and MWCNT/PMMA Nanocomposites by Contact Angle Measurement Tue, 06 Jan 2015 07:21:45 +0000 The dispersion state of individual MWCNT in the polymer matrix influences the mechanical, thermal, and electrical properties of the resulting composite. One method of obtaining a good dispersion state of MWCNT in a polymer matrix is to functionalize the surface of MWCNT using various treatments to enhance the surface energy and increase the dispersibility of MWCNT. In this study, wettability and surface energy of UV/O3 and acid-treated multiwall carbon nanotubes (MWCNTs) and its polymethyl methacrylate (PMMA) polymer nanocomposites were measured using contact angle analysis in various solvent media. Contact angle analysis was based on ethylene glycol-water-glycerol probe liquid set and data was further fitted into geometric mean (Fowkes), van Oss-Chaudhury-Good (GvOC), and Chang-Qing-Chen (CQC) models to determine both nonpolar and acid base surface energy components. Analysis was conducted on MWCNT thin films subjected to different levels of UV/O3 and acid treatments as well as their resulting MWCNT/PMMA nanocomposites. Contact angle analysis of thin films and nanocomposites revealed that the total surface energy of all samples was well fitted with each other. In addition, CQC model was able to determine the surface nature and polarity of MWCNT and its nanocomposites. Results indicated that the wettability changes in the thin film and its nanocomposites are due to the change in surface chemistry. Finally, electrical properties of nanocomposites were measured to investigate the effect of surface functionality (acid or basic) on the MWCNT surfaces. Seil Kim, Abdullah A. Kafi, Ehsan Bafekpour, Young-In Lee, Bronwyn Fox, Manwar Hussain, and Yong-Ho Choa Copyright © 2015 Seil Kim et al. All rights reserved. Electromechanical Response of Conductive Porous Structure Tue, 06 Jan 2015 06:50:15 +0000 Porous conductors with large surface-volume ratios have been applied to a variety of fields, including absorbents, flexible heaters, and electrodes for supercapacitors. In this study, we implemented sensitive pressure sensors using the mechanical and electrical characteristics of conductive porous structures manufactured by immersing sponges into a carbon nanotube solution and then measured the change in resistance. When pressure was applied to conductive sponges, carbon nanotubes were attached to each other and the resistance was reduced by up to 20%. The carbon nanotube sponges, which were soft and had superior elasticity, were quickly stabilized without any changes taking place in their shape, and they showed consistent change in resistance during experiments of repetitive pressure. The pressure devices based on conductive porous sponges were connected to single-walled carbon nanotube field effect transistors (SWCNT-FETs) and changes in their characteristics were investigated according to external pressure. Hye-Mi So, Cheolmin Park, and Won Seok Chang Copyright © 2015 Hye-Mi So et al. All rights reserved. Thermoluminescence of Novel Zinc Oxide Nanophosphors Obtained by Glycine-Based Solution Combustion Synthesis Thu, 01 Jan 2015 12:22:05 +0000 High-dose thermoluminescence dosimetry properties of novel zinc oxide nanophosphors synthesized by a solution combustion method in a glycine-nitrate process are presented for the very first time in this work. Sintered particles with sizes ranging between ~500 nm and ~2 μm were obtained by annealing the synthesized ZnO at 900°C during 2 h in air. X-ray diffraction patterns indicate the presence of the ZnO hexagonal phase, without any remaining nitrate peaks observed. Thermoluminescence glow curves of ZnO obtained after being exposed to beta radiation consists of two maxima: one located at ~149°C and another at ~308°C, the latter being the dosimetric component of the curve. The integrated TL fading displays an asymptotic behavior for times longer than 16 h between irradiation and the corresponding TL readout, as well as a linear behaviour of the dose response without saturation in the studied dose interval (from 12.5 up to 400 Gy). Such features place synthesized ZnO as a promising material for high-dose radiation dosimetry applications. V. R. Orante-Barrón, F. M. Escobar-Ochoa, C. Cruz-Vázquez, and R. Bernal Copyright © 2015 V. R. Orante-Barrón et al. All rights reserved. Degradation of TCE by TEOS Coated nZVI in the Presence of Cu(II) for Groundwater Remediation Wed, 31 Dec 2014 13:54:02 +0000 The removal of TCE by nanofer zero valent iron (nanofer ZVI) coated with tetraethyl orthosilicate (TEOS) in the presence of Cu(II) at different environmental conditions was studied. The kinetics of TCE degradation by nanofer ZVI was determined. At a dosage of 10 mg of nanofer ZVI, almost 63% of TCE was removed, when Cu(II) and TCE were present. It contrasts with 42% degradation of TCE in the absence of Cu(II). SEM/EDS images indicated that Cu(II) is reduced to form and Cu2O. These formations are considered to be responsible for enhancing TCE degradation. Direct reduction involves hydrogenolysis and -elimination in the transformation of TCE, while indirect reduction involves atomic hydrogen and no direct electron transfer from the metal to reactants. The reduction of activation energy was also noted indicating that the rate limiting step for TCE degradation in the presence of Cu(II) is surface chemical reaction rather than diffusion. Most of iron present in nanofer ZVI get dissolved causing the generation of localized positive charge regions and form metal chlorides. Local accumulation of hydrochloric acid inside the pits regenerates new reactive surfaces to serve as sources of continuous electron generation. No significant effect of TCE was noticed for Cu(II) sequestration. Amruthur S. Ramamurthy and Mahmoud M. Eglal Copyright © 2014 Amruthur S. Ramamurthy and Mahmoud M. Eglal. All rights reserved. A Comparative Study of Bioartificial Bone Tissue Poly-L-lactic Acid/Polycaprolactone and PLLA Scaffolds Applied in Bone Regeneration Wed, 31 Dec 2014 12:36:31 +0000 Bioartificial bone tissue engineering is an increasingly popular technique to repair bone defect caused by injury or disease. This study aimed to investigate the feasibility of PLLA/PCL (poly-L-lactic acid/polycaprolactone) by a comparison study of PLLA/PCL and PLLA scaffolds applied in bone regeneration. Thirty healthy mature New Zealand rabbits on which 15 mm distal ulna defect model had been established were selected and then were divided into three groups randomly: group A (repaired with PLLA scaffold), group B (repaired with PLLA/PCL scaffold), and group C (no scaffold) to evaluate the bone-remodeling ability of the implants. Micro-CT examination revealed the prime bone regeneration ability of group B in three groups. Bone mineral density of surgical site in group B was higher than group A but lower than group C. Meanwhile, the bone regeneration in both groups A and B proceeded with signs of inflammation for the initial fast degradation of scaffolds. As a whole, PLLA/PCL scaffolds in vivo initially degrade fast and were better suited to repair bone defect than PLLA in New Zealand rabbits. Furthermore, for the low mineral density of new bone and rapid degradation of the scaffolds, more researches were necessary to optimize the composite for bone regeneration. Weizong Weng, Shaojun Song, Liehu Cao, Xiao Chen, Yuanqi Cai, Haihang Li, Qirong Zhou, Jun Zhang, and Jiacan Su Copyright © 2014 Weizong Weng et al. All rights reserved. Effect of CuO Nanoparticles over Isolated Bacterial Strains from Agricultural Soil Wed, 31 Dec 2014 11:22:50 +0000 The increased use of the nanoparticles (NPs) on several processes is notorious. In contrast the ecotoxicological effects of NPs have been scarcely studied. The main current researches are related to the oxide metallic NPs. In the present work, fifty-six bacterial strains were isolated from soil, comprising 17 different OTUs distributed into 3 classes: Bacilli (36 strains), Flavobacteria (2 strains), and Gammaproteobacteria (18 strains). Copper oxide nanoparticles (CuONPs) were synthesized using a process of chemical precipitation. The obtained CuONPs have a spherical shape and primary size less than 17 nm. Twenty-one strains were used to evaluate the cytotoxicity of CuONPs and 11 of these strains showed high sensibility. Among those 11 strains, 4 (Brevibacillus laterosporus strain CSS8, Chryseobacterium indoltheticum strain CSA28, and Pantoea ananatis strains CSA34 and CSA35) were selected to determine the kind of damage produced. The CuONPs toxic effect was observed at expositions over 25 mg·L−1 and the damage to cell membrane above 160 mg·L−1. The electron microscopy showed the formation of cavities, holes, membrane degradation, blebs, cellular collapse, and lysis. These toxic effects may probably be due to the ions interaction, the oxide-reduction reactions, and the generation of reactive species. Sandra I. Concha-Guerrero, Elcia Margareth Souza Brito, Hilda A. Piñón-Castillo, S. H. Tarango-Rivero, César A. Caretta, Antonia Luna-Velasco, Robert Duran, and Erasmo Orrantia-Borunda Copyright © 2014 Sandra I. Concha-Guerrero et al. All rights reserved. A Comparative Study on Magnetostructural Properties of Barium Hexaferrite Powders Prepared by Polyethylene Glycol Wed, 31 Dec 2014 00:10:53 +0000 Nanocrystalline particles of barium hexaferrite were synthesized by a sol-gel combustion route using nitrate-citrate gels prepared from metal nitrates and citric acid solutions with Fe/Ba molar ratio 12. The present paper aims to study the effect of addition of polyethylene glycol (PEG) solutions with different molecular weights (MW: 400, 2000, and 10.000 g/mol) on magnetostructural properties of barium hexaferrite. The formation of the barium hexaferrite was inspected using X-ray diffraction (XRD) analysis, Fourier transform infrared (FT-IR) analysis, thermogravimetric (TGA) analysis, scanning electron microscopy (SEM) analysis and vibrating sample magnetometer (VSM) analysis for magnetic measurements. Zehra Durmus Copyright © 2014 Zehra Durmus. All rights reserved. Stop Flow Lithography Synthesis and Characterization of Structured Microparticles Wed, 31 Dec 2014 00:10:52 +0000 In this study, the synthesis of nonspherical composite particles of poly(ethylene glycol) diacrylate (PEG-DA)/SiO2 and PEG-DA/Al2O3 with single or multiple vias and the corresponding inorganic particles of SiO2 and Al2O3 synthesized using the Stop Flow Lithography (SFL) method is reported. Precursor suspensions of PEG-DA, 2-hydroxy-2-methylpropiophenone, and SiO2 or Al2O3 nanoparticles were prepared. The precursor suspension flows through a microfluidic device mounted on an upright microscope and is polymerized in an automated process. A patterned photomask with transparent geometric features masks UV light to synthesize the particles. Composite particles with vias were synthesized and corresponding inorganic SiO2 and Al2O3 particles were obtained through polymer burn-off and sintering of the composites. The synthesis of porous inorganic particles of SiO2 and Al2O3 with vias and overall dimensions in the range of ~35–90 µm was achieved. BET specific surface area measurements for single via inorganic particles were 56–69 m2/g for SiO2 particles and 73–81 m2/g for Al2O3 particles. Surface areas as high as 114 m2/g were measured for multivia cubic SiO2 particles. The findings suggest that, with optimization, the particles should have applications in areas where high surface area is important such as catalysis and sieving. David Baah, Tobias Donnell, Sesha Srinivasan, and Tamara Floyd-Smith Copyright © 2014 David Baah et al. All rights reserved. Graphene Channel Liquid Container Field Effect Transistor as pH Sensor Wed, 31 Dec 2014 00:10:50 +0000 Graphene channel liquid container field effect transistor pH sensor with interdigital microtrench for liquid ion testing is presented. Growth morphology and pH sensing property of continuous few-layer graphene (FLG) and quasi-continuous monolayer graphene (MG) channels are compared. The experiment results show that the source-to-drain current of the graphene channel FET has a significant and fast response after adsorption of the measured molecule and ion at the room temperature; at the same time, the FLG response time is less than 4 s. The resolution of MG (0.01) on pH value is one order of magnitude higher than that of FLG (0.1). The reason is that with fewer defects, the MG is more likely to adsorb measured molecule and ion, and the molecules and ions can make the transport property change. The output sensitivities of MG are from 34.5% to 57.4% when the pH value is between 7 and 8, while sensitivity of FLG is 4.75% when the . The sensor fabrication combines traditional silicon technique and flexible electronic technology and provides an easy way to develop graphene-based electrolyte gas sensor or even biological sensors. Xin Li, Junjie Shi, Junchao Pang, Weihua Liu, Hongzhong Liu, and Xiaoli Wang Copyright © 2014 Xin Li et al. All rights reserved. Nanomaterials for Nanooptoelectronics Device Applications Tue, 30 Dec 2014 07:38:55 +0000 Chien-Jung Huang, Chi-Chih Liao, Mau-Phon Houng, Fu-Ken Liu, and Ying-Chung Chen Copyright © 2014 Chien-Jung Huang et al. All rights reserved. Analysis of the High Conversion Efficiencies β-FeSi2 and BaSi2 n-i-p Thin Film Solar Cells Mon, 29 Dec 2014 14:07:42 +0000 Both β-FeSi2 and BaSi2 are silicides and have large absorption coefficients; thus they are very promising Si-based new materials for solar cell applications. In this paper, the dc - characteristics of n-Si/i-βFeSi2/p-Si and n-Si/i-BaSi2/p-Si thin film solar cells are investigated by solving the charge transport equations with optical generations. The diffusion current densities of free electron and hole are calculated first. Then the drift current density in the depletion regions is obtained. The total current density is the sum of diffusion and drift current densities. The conversion efficiencies are obtained from the calculated - curves. The optimum conversion efficiency of n-Si/i-βFeSi2/p-Si thin film solar cell is 27.8% and that of n-Si/i-BaSi2/p-Si thin film solar cell is 30.4%, both are larger than that of Si n-i-p solar cell ( is 20.6%). These results are consistent with their absorption spectrum. The calculated conversion efficiency of Si n-i-p solar cell is consistent with the reported researches. Therefore, these calculation results are valid in this work. Jung-Sheng Huang, Kuan-Wei Lee, and Yu-Hsiang Tseng Copyright © 2014 Jung-Sheng Huang et al. All rights reserved. Influence of Nanoparticles and Graphite Foam on the Supercooling of Acetamide Mon, 29 Dec 2014 12:37:59 +0000 Acetamide is a promising phase change materials (PCMs) for thermal storage,but the large supercooling during the freezing process has limited its application. In this study, we prepared acetamide-SiO2 composites by adding nano-SiO2 into acetamide. This modified PCM was then impregnated into the porous graphite foam forming acetamide-SiO2-graphite foam form-stable composites. These composites were subjected to melting-solidification cycles 50 times; the time-temperature curves were tracked and recorded during these cycles. The time-temperature curves showed that, for the acetamide containing 2 wt. % SiO2, the supercooling phenomenon was eliminated and the material’s performance was stable for 50 cycles. The solidification temperature of the acetamide-SiO2-graphite foam samples was 65°C and the melting temperature was lowered to 65°C. The samples exhibited almost no supercooling and the presence of SiO2 had no significant effect on the melting-solidification temperature. The microscopic supercooling of the acetamide-SiO2 composite was measured using differential scanning calorimetry (DSC). The results indicated that when the content of SiO2 was 1 wt. to 2 wt. %, the supercooling could be reduced to less than 10°C and heat was sufficiently released during solidification. Finally, a set of algorithms was derived using MATLAB software for simulating the crystallization of samples based on the classical nucleation theory. The results of the simulation agreed with the experiment results. Jia Yu, Xuan Chen, Xiaoliang Ma, Qingfei Song, Yukun Zhao, and Jiahao Cao Copyright © 2014 Jia Yu et al. All rights reserved.