Journal of Nanomaterials http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. In Vitro Degradation of Poly(caprolactone)/nHA Composites Thu, 30 Oct 2014 07:41:46 +0000 http://www.hindawi.com/journals/jnm/2014/802435/ The degradation behavior and mechanical properties of polycaprolactone/nanohydroxyapatite composite scaffolds are studied in phosphate buffered solution (PBS), at 37°C, over 16 weeks. Under scanning electron microscopy (SEM), it was observed that the longer the porous scaffolds remained in the PBS, the more significant the thickening of the pore walls of the scaffold morphology was. A decrease in the compressive properties, such as the modulus and the strength of the PCL/nHA composite scaffolds, was observed as the degradation experiment progressed. Samples with high nHA concentrations degraded more significantly in comparison to those with a lower content. Pure PCL retained its mechanical properties comparatively well in the study over the period of degradation. After the twelfth week, the results obtained by GPC analysis indicated a significant reduction in their molecular weight. The addition of nHA particles to the scaffolds accelerated the weight loss of the composites and increased their capacity to absorb water during the initial degradation process. The addition of these particles also affected the degradation behavior of the composite scaffolds, although they were not effective at compensating the decrease in pH prompted by the degradation products of the PCL. Esperanza Díaz, Iban Sandonis, and María Blanca Valle Copyright © 2014 Esperanza Díaz et al. All rights reserved. Synthesis, Characterization, and Thermal and Proton Conductivity Evaluation of 2,5-Polybenzimidazole Composite Membranes Wed, 29 Oct 2014 11:26:47 +0000 http://www.hindawi.com/journals/jnm/2014/460232/ In this contribution, composite membranes (CM-D and CM-S) of 2,5-polybenzimidazole (PBI) were synthesized by adding inorganic heteropoly acids (IHA-D and IHA-S). IHA-D and IHA-S were synthesized by condensation reaction of silicotungstic acid with tetraethyl orthosilicate (TEOS) in the absence and presence of mesoporous silica (SiO2), respectively. The synthesized composites were structurally and morphologically characterized and further investigated the functional relationships between the materials structure and proton conductivity. The proton conductivity as well as thermal stability was found to be higher for composite membranes which suggest that both properties are highly contingent on mesoporous silica. The composite membrane with mesoporous silica shows high thermal properties and proton conductivity. IHA-D shows proton conductivity of almost  Scm−1 while IHA-S exhibited  Scm−1 in nonhumidity imposing condition (150°C) which is higher than pure PBI. Thus introduction of inorganic heteropoly acid to PBI is functionally preferable as it results in increase of ion conductivity of PBI and can be better candidates for high temperature PEMFC. Jin-Woo Lee, Kwangin Kim, Sher Bahadar Khan, Patrick Han, Jongchul Seo, Wonbong Jang, and Haksoo Han Copyright © 2014 Jin-Woo Lee et al. All rights reserved. The Effect of Ultrafine Magnesium Hydroxide on the Tensile Properties and Flame Retardancy of Wood Plastic Composites Tue, 28 Oct 2014 06:04:09 +0000 http://www.hindawi.com/journals/jnm/2014/945308/ The effect of ultrafine magnesium hydroxide (UMH) and ordinary magnesium hydroxide (OMH) on the tensile properties and flame retardancy of wood plastic composites (WPC) were investigated by tensile test, oxygen index tester, cone calorimeter test, and thermogravimetric analysis. The results showed that ultrafine magnesium hydroxide possesses strengthening and toughening effect of WPC. Scanning electron micrograph (SEM) of fracture section of samples provided the positive evidence that the tensile properties of UMH/WPC are superior to that of WPC and OMH/WPC. The limited oxygen index (LOI) and cone calorimeter test illustrated that ultrafine magnesium hydroxide has stronger flame retardancy and smoke suppression effect of WPC compared to that of ordinary magnesium hydroxide. The results of thermogravimetric analysis implied that ultrafine magnesium hydroxide can improve the char structure which plays an important role in reducing the degradation speed of the inner matrix during combustion process and increases the char residue at high temperature. Zhiping Wu, Na Hu, Yiqiang Wu, Shuyun Wu, and Zu Qin Copyright © 2014 Zhiping Wu et al. All rights reserved. Solvothermal Synthesis of Mn3O4 Nanoparticle/Graphene Sheet Composites and Their Supercapacitive Properties Mon, 27 Oct 2014 12:57:03 +0000 http://www.hindawi.com/journals/jnm/2014/190529/ Mn3O4 nanoparticle/graphene sheet (GM) composites were synthesized via a one-pot and low-cost solvothermal process in an ethanol solution. The as-prepared materials were characterized by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. Results showed that the nanosized Mn3O4 particles had tetragonal hausmannite structure and were successfully loaded on the graphene sheets. Moreover, the electrochemical performances of GM composites produced by different mass percents of Mn2+/graphite oxide (GO) were evaluated by means of cyclic voltammetry and galvanostatic charge-discharge studies. The composite prepared with Mn2+/GO mass percent of 10 : 90 showed a high specific capacitance of 245 F/g at 5 mV/s in the 6 M KOH solution and better long-term stability along with 81% of its initial capacitance after 1200 cycles at 0.5 A/g. Y. F. Liu, G. H. Yuan, Z. H. Jiang, and Z. P. Yao Copyright © 2014 Y. F. Liu et al. All rights reserved. Efficient Ab-Initio Electron Transport Calculations for Heterostructures by the Nonequilibrium Green’s Function Method Mon, 27 Oct 2014 12:30:56 +0000 http://www.hindawi.com/journals/jnm/2014/172169/ We present an efficient computation technique for ab-initio electron transport calculations based on density functional theory and the nonequilibrium Green’s function formalism for application to heterostructures with two-dimensional (2D) interfaces. The computational load for constructing the Green’s functions, which depends not only on the energy but also on the 2D Bloch wave vector along the interfaces and is thus catastrophically heavy, is circumvented by parallel computational techniques with the message passing interface, which divides the calculations of the Green’s functions with respect to energy and wave vectors. To demonstrate the computational efficiency of the present code, we perform ab-initio electron transport calculations of Al(100)-Si(100)-Al(100) heterostructures, one of the most typical metal-semiconductor-metal systems, and show their transmission spectra, density of states (DOSs), and dependence on the thickness of the Si layers. Hirokazu Takaki, Nobuhiko Kobayashi, and Kenji Hirose Copyright © 2014 Hirokazu Takaki et al. All rights reserved. Comparison between Base Metals and Platinum Group Metals in Nitrogen, M Codoped TiO2 (M = Fe, Cu, Pd, Os) for Photocatalytic Removal of an Organic Dye in Water Mon, 27 Oct 2014 11:40:25 +0000 http://www.hindawi.com/journals/jnm/2014/962102/ The photocatalytic performance of a number of nonmetal and metal codoped TiO2 for the degradation of eosin yellow under simulated solar radiation was investigated. The synthesised materials were characterised by FTIR, Raman spectroscopy, XRD, DRUV-Vis, SEM, and TEM. The N, metal codoped TiO2 containing 0.5 wt.% of the metal consisted mainly of the anatase phase, with a particle size range of 15–28 nm. The particles were largely spherical and shifted the absorption edge well into the visible region. Band gap reduction was more pronounced for the N, PGM codoped TiO2 compared to N, base metal codoped samples. Codoping led to an enhancement in the photocatalytic activity of the materials for the degradation of eosin yellow. N, Pd codoped TiO2 was the most effective photocatalyst (99.9% dye removal) while N, Cu codoped TiO2 showed the least activity (25.5% removal). The mechanism for the photocatalytic enhancement was proposed on the basis of formation of an electron deficient Schottky barrier at the semiconductor-metal interface, which acts as an electron sink and thus retards electron-hole recombination. It was shown that the ability of the photocatalyst to degrade the dye depends on the nature and type of the metal dopant in the codoped TiO2 system. Alex T. Kuvarega, Rui W. M. Krause, and Bhekie B. Mamba Copyright © 2014 Alex T. Kuvarega et al. All rights reserved. Directed Deposition of Nickel Nanoparticles Using Self-Assembled Organic Template Thu, 23 Oct 2014 09:13:00 +0000 http://www.hindawi.com/journals/jnm/2014/861056/ Self-assembled organic monolayers are useful templates for nanofabrication. Ordered layer of long alkyl-chain molecules can direct the wet chemical deposition of metallic coatings on different substrates. Ordered structures of fatty acids and their motions on the phenyloctane/HOPG interface are observed by scanning tunneling microscopy (STM). Modification of self-assembled fatty acid patterns due to hydroxamic acid presence is also in the focus of the research. Fatty acid layer formation, the structure of the formed thin film on solid/liquid interface, and simultaneous nickel colloidal deposition have been investigated. András Paszternák, Meital Shviro, Lajos Nyikos, and David Zitoun Copyright © 2014 András Paszternák et al. All rights reserved. Fractional Contributions of Defect-Originated Photoluminescence from CuInS2/ZnS Coreshells for Hybrid White LEDs Wed, 22 Oct 2014 00:00:00 +0000 http://www.hindawi.com/journals/jnm/2014/979875/ The wide optical tunability and broad spectral distribution of CuInS2/ZnS (CIS/ZnS) coreshells are key elements for developing the hybrid white light emitting diodes where the nanoparticles are stacked on the blue LEDs. Two and coreshells are utilized for the hybrid white LED development. The time-resolved spectroscopy of and reveals the correlation between the fast, intermediate, and slow decay components and the interface-trapped state and shallow- and deep-trapped states, although the fractional amplitudes of photoluminescence (PL) decay components are widely distributed throughout the entire spectra. The temperature-resolved spectroscopy explains that the PL from deep-trapped donor-acceptor (DA) state has relatively large thermal quenching, due to the relative Coulomb interaction of DA pairs, compared to the thermal quenching of PL from interface defect state and shallow-trapped DA state. A good spectral coupling between the blue diode excitation and the PL from CIS/ZnS leads to the realization of hybrid white LEDs. Quinton Rice, Sangram Raut, Rahul Chib, Zygmunt Gryczynski, Ignacy Gryczynski, Wenjin Zhang, Xinhua Zhong, Mahmoud Abdel-Fattah, Bagher Tabibi, and Jaetae Seo Copyright © 2014 Quinton Rice et al. All rights reserved. Enhanced Photocatalytic Activity of W-Doped and W-La-Codoped TiO2 Nanomaterials under Simulated Sunlight Tue, 21 Oct 2014 09:43:41 +0000 http://www.hindawi.com/journals/jnm/2014/943796/ W-doped TiO2 and W-La-codoped TiO2 nanomaterials were successfully synthesized via the sol-gel method. The products were characterized by X-ray diffraction, UV-vis diffuse reflectance spectrophotometer, transmission electron microscopy, and X-ray photoelectron spectroscopy. The presence of W and La results in significant red shift of absorption edge for TiO2-based nanomaterials. The weight ratios of La and W in the composites play important roles in the absorption edge for TiO2-based nanomaterials. The photocatalytic activities of both W-doped TiO2 and W-La-codoped TiO2 photocatalysts for decolorization of methyl orange solution were evaluated under simulated sunlight irradiation. The results showed that both W-doped and W-La-codoped can effectively improve the photocatalytic behaviors of TiO2 nanomaterials ascribed to the improved photoinduced charge carriers separation, enhanced light absorption, and large surface area. Furthermore, W-La-codoped TiO2 exhibited higher photocatalytic activity than W-doped TiO2. Considering their high photocatalytic activity, the doped TiO2 nanomaterials could be applied in wastewater treatment and environmental purification. Chenghe Hua, Xiaoli Dong, Xiuying Wang, Mang Xue, Xiufang Zhang, and Hongchao Ma Copyright © 2014 Chenghe Hua et al. All rights reserved. The Effect of Chemical and High-Pressure Homogenization Treatment Conditions on the Morphology of Cellulose Nanoparticles Sun, 19 Oct 2014 09:45:19 +0000 http://www.hindawi.com/journals/jnm/2014/582913/ Cellulose nanoparticles were fabricated from microcrystalline cellulose (MCC) through combined acid hydrolysis with sulfuric and hydrochloric acids and high-pressure homogenization. The effect of acid type, acid-to-MCC ratio, reaction time, and numbers of high-pressure homogenization passes on morphology and thermal stability of the nanoparticles was studied. An aggressive acid hydrolysis was shown to lead to rod-like cellulose nanocrystals with diameter about 10 nm and lengths in the range of 50–200 nm. Increased acid-to-MCC ratio and number of homogenization treatments reduced the dimension of the nanocrystals produced. Weak acid hydrolysis treatment led to a network of cellulose nanofiber bundles having diameters in the range of 20–100 nm and lengths of a few thousands of nanometers. The high-pressure homogenization treatment helped separate the nanofiber bundles. The thermal degradation behaviors characterized by thermogravimetric analysis at nitrogen atmosphere indicated that the degradation of cellulose nanocrystals from sulfuric acid hydrolysis started at a lower temperature and had two remarkable pyrolysis processes. The thermal stability of cellulose nanofibers produced from hydrochloric acid hydrolysis improved significantly. Suxia Ren, Xiuxuan Sun, Tingzhou Lei, and Qinglin Wu Copyright © 2014 Suxia Ren et al. All rights reserved. Fano Resonance of the Symmetry-Reduced Metal Bar Grating Structure Thu, 16 Oct 2014 07:23:31 +0000 http://www.hindawi.com/journals/jnm/2014/341050/ We demonstrate that Fano resonance and even multipole Fano resonance can be obtained in a symmetry-reduced structure composed of gold bars with different bar sizes or bar shapes on a layer of dielectric. There is a transparency window opened within the frequency region of the absorptive dipole resonance by metallic bars, as long as the narrow grating waveguide mode induced by reducing symmetry is coincided in spectrum with the dipole resonance such that a destructive interference happens between these two resonant modes. Line shape of the transmission spectra of the nanostructure can be modulated effectively by changing the size or shape of the series of metal bars. The results found can be useful in the design of novel optical device. Suxia Xie, Zhijian Li, Renlong Zhou, Jie Zhan, Qiong Liu, Lingxi Wu, and Bingju Zhou Copyright © 2014 Suxia Xie et al. All rights reserved. PANI-Ag-Cu Nanocomposite Thin Films Based Impedimetric Microbial Sensor for Detection of E. coli Bacteria Wed, 15 Oct 2014 11:48:03 +0000 http://www.hindawi.com/journals/jnm/2014/951640/ PANI-Ag-Cu nanocomposite thin films were prepared by sol-gel method and deposited on the glass substrate using spin coating technique. Polyaniline was synthesized by chemical oxidative polymerization of aniline monomer in the presence of nitric acid. The films were characterized using XRD, FTIR, and UV-Visible spectroscopy. The performance of the sensor was conducted using electrochemical impedance spectroscopy to obtain the change in impedance of the sensor film before and after incubation with E. coli bacteria in water. The peaks in XRD pattern confirm the presence of Ag and Cu nanoparticles in face-centered cubic structure. FTIR analysis shows the stretching of N–H in the polyaniline structure. The absorption band from UV-Visible spectroscopy shows high peaks between 400 nm and 500 nm which indicate the presence of Ag and Cu nanoparticles, respectively. Impedance analysis indicates that the change in impedance of the films decreases with the presence of E. coli. The sensitivity on E. coli increases for the sample with high concentration of Cu. Huda Abdullah, Norshafadzila Mohammad Naim, Noor Azwen Noor Azmy, and Aidil Abdul Hamid Copyright © 2014 Huda Abdullah et al. All rights reserved. Comparative Study on Electronic, Emission, Spontaneous Property of Porous Silicon in Different Solvents Wed, 15 Oct 2014 11:30:41 +0000 http://www.hindawi.com/journals/jnm/2014/682571/ Luminescent porous silicon (Psi) fabricated by simple chemical etching technique in different organic solvents was studied. By quantifying the silicon wafer piece, optical properties of the Psi in solutions were investigated. Observation shows that no photoluminescence light of Psi in all solvents is emitted. Morphology of Psi in different solvents indicates that the structure and distribution of Psi are differently observed. Particles are uniformly dispersive with the sizes around more or less 5–8 nm. The crystallographic plane and high crystalline nature of Psi is observed by selected area diffraction (SED) and XRD. Electronic properties of Psi in solutions are influenced due to the variation of quantity of wafer and nature of solvent. Influence in band gaps of Psi calculated by Tauc’s method is obtained due to change of absorption edge of Psi in solvents. PL intensities are observed to be depending on quantity of silicon wafer, etched cross-section area on wafer surface. Effects on emission peaks and bands of Psi under temperature annealing are observed. The spontaneous signals of Psi measured under high power Pico second laser 355 nm source are significant, influenced by the nature of solvent, pumped energy, and quantity of Si wafer piece used in etching process. M. Naziruddin Khan, M. A. Majeed Khan, A. S. Al Dwayyan, and J. Puzon Labis Copyright © 2014 M. Naziruddin Khan et al. All rights reserved. Development, Characterization, and Evaluation of PSMA-Targeted Glycol Chitosan Micelles for Prostate Cancer Therapy Wed, 15 Oct 2014 10:36:00 +0000 http://www.hindawi.com/journals/jnm/2014/462356/ Prostate cancer-binding peptides- (PCP-) modified polymeric micelles were prepared and used for the treatment of prostate-specific membrane antigen- (PSMA-) expressing prostate cancer in a target-specific manner. Cholesterol-modified glycol chitosan (CHGC) was synthesized. PCP-conjugated CHGC (PCP-CHGC) micelles were fabricated and characterized. The degree of substitution was 5.2 PCP groups and 5.8 cholesterol groups per 100 sugar residues of glycol chitosan. The critical aggregation concentration (CAC) of PCP-CHGC copolymer was 0.0254 mg/mL. Doxorubicin (DOX) was chosen as a model antitumor drug. The DOX-loaded micelles were prepared by an o/w method. The mean diameter of DOX-loaded PCP-CHGC (DOX-PCP-CHGC) micelles was 293 nm determined by dynamic light scattering (DLS). DOX released from drug-loaded micelles was in a biphasic manner. DOX-PCP-CHGC micelles exhibited higher cytotoxicity in vitro against PSMA-expressing LNCaP cells than DOX-loaded CHGC (DOX-CHGC) micelles. Moreover, the cellular uptake of DOX-PCP-CHGC micelles determined by confocal laser scanning microscopy (CLSM) and flow cytometry was higher than that of DOX-CHGC micelles in LNCaP cells. Importantly, DOX-PCP-CHGC micelles demonstrated stronger antitumor efficacy against LNCaP tumor xenograft models than doxorubicin hydrochloride and DOX-CHGC micelles. Taken together, this study provides a potential way in developing PSMA-targeted drug delivery system for prostate cancer therapy. Jing Xu, Jingmou Yu, Xiao Xu, Liangliang Wang, Yonghua Liu, Lixin Li, Jianguo Zhao, and Ming He Copyright © 2014 Jing Xu et al. All rights reserved. Hydrothermal Synthesis of Boron-Doped MnO2 and Its Decolorization Performance Tue, 14 Oct 2014 10:06:26 +0000 http://www.hindawi.com/journals/jnm/2014/175924/ To functionalize MnO2 with foreign ions is one of the commonly used methods to improve the adsorption/oxidation properties of MnO2. Boron-doped MnO2 was prepared by the reaction of MnSO4, KMnO4, and boric acid by a facile hydrothermal method. Boron-MnO2 was characterized by X-ray diffraction (XRD), Raman spectra, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), selected area electron diffraction pattern (SAED), and X-ray photo-electron spectroscopy (XPS) techniques. The characterization of XPS and EDX confirms that boron has been doped into MnO2, but the boron dopant has no obvious effect on the crystallization of MnO2 as shown by the results of XRD and Raman characterization. The boron-doped MnO2 nanorods display high performance in the methyl orange degradation with a decolorization degree of 90% in 2 min (5% B-MnO2 dosage, 5 mg; methyl orange concentration, 20 mg L−1). Ming Sun, Ting Lin, Gao Cheng, Fei Ye, and Lin Yu Copyright © 2014 Ming Sun et al. All rights reserved. Gold Nanoparticle-Graphene Oxide Nanocomposites That Enhance the Device Performance of Polymer Solar Cells Tue, 14 Oct 2014 08:02:45 +0000 http://www.hindawi.com/journals/jnm/2014/736879/ Metal nanoparticle-decorated graphene oxides are promising materials for use in various optoelectronic applications because of their unique plasmonic properties. In this paper, a simple, environmentally friendly method for the synthesis of gold nanoparticle-decorated graphene oxide that can be used to improve the efficiency of organic photovoltaic devices (OPVs) is reported. Here, the amino acid glycine is employed as an environmentally friendly reducing reagent for the reduction of gold ions in the graphene oxide solutions. Transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, UV-Vis spectroscopy, and Raman spectroscopy are used to characterize the material properties of the resulting nanomaterials. Furthermore, these nanocomposites are employed as the anode buffer layer in OPVs to trigger surface plasmonic resonance, which improved the efficiency of the OPVs. The results indicate that such nanomaterials appear to have great potential for application in OPVs. Ming-Kai Chuang, Fang-Chung Chen, and Chain-Shu Hsu Copyright © 2014 Ming-Kai Chuang et al. All rights reserved. Preparation, Characterization, and Bioactivity of Chitosan Microspheres Containing Basic Fibroblast Growth Factor Tue, 14 Oct 2014 00:00:00 +0000 http://www.hindawi.com/journals/jnm/2014/534287/ The aim of this study is to evaluate, prepare, and characterize bioactivity of chitosan microspheres loaded with bFGF for providing sustained release of bFGF. Porous chitosan microspheres were prepared by freeze-drying process based on the interaction between chitosan and tripolyphosphate (TPP). The bFGF-loaded chitosan microspheres were well interconnected and have a narrow size distribution, spherical shape, and positive surface charges. The bFGF-loading capacity and encapsulation efficiency were 7.57 mg/g and 95.1%, respectively. Results of in vitro release showed that the extent of release was 82.1% at Day 25. Schwann cells were used as an in vitro model for cell response to bFGF and bFGF-loaded chitosan microspheres. Results indicated that the number, cell viability, and percentage of cells G2/M+S phase in the bFGF groups are higher than those in the bFGF-loaded chitosan microspheres groups before culturing for 2 days. However, the number, cell viability, and percent of cells G2/M+S phase in the bFGF-loaded chitosan microspheres groups are significantly higher than those in the bFGF groups after culture for 4 and 8 days. These findings indicated that bFGF-loaded chitosan microspheres may help to decrease the release of bFGF and provide a suitable three-dimensional environment for cell growth and proliferation. Bo Lv, Yue Wang, and Wei Chen Copyright © 2014 Bo Lv et al. All rights reserved. Effects of Wavenumber and Chirality on the Axial Compressive Behavior of Wavy Carbon Nanotubes: A Molecular Mechanics Study Mon, 13 Oct 2014 10:32:17 +0000 http://www.hindawi.com/journals/jnm/2014/769618/ The effects of wavenumber and chirality on the axial compressive behavior and properties of wavy carbon nanotubes (CNTs) with multiple Stone-Wales defects are investigated using molecular mechanics simulations with the adaptive intermolecular reactive empirical bond-order potential. The wavy CNTs are assumed to be point-symmetric with respect to their axial centers. It is found that the wavy CNT models, respectively, exhibit a buckling point and long wavelength buckling mode regardless of the wavenumbers and chiralities examined. It is also found that the wavy CNTs have nearly the same buckling stresses as their pristine straight counterparts. Masaki Kawachi, Yusuke Kinoshita, and Nobutada Ohno Copyright © 2014 Masaki Kawachi et al. All rights reserved. Accelerated Weatherability of the Low-Density Polyethylene Nanocomposites with Silica, Clay, and Zinc Oxide Mon, 13 Oct 2014 10:11:01 +0000 http://www.hindawi.com/journals/jnm/2014/516406/ Nanocomposites based on low-density polyethylene (LDPE) with MMT clay, nanosilica, and nanoscale zinc oxide (at 5 wt.%) were prepared by melt processing and evaluated for durability using laboratory accelerated weathering. The changes in tensile properties of the nanocomposites with the duration of exposure were compared to data from natural weathering outdoors. The enhancement of degradation rates of the LDPE matrix by the presence of nanofillers in accelerated weathering is reported. Halim Hamid Redhwi, Mohammad Nahid Siddiqui, Anthony L. Andrady, and Syed Hussain Copyright © 2014 Halim Hamid Redhwi et al. All rights reserved. Study of Tribological Properties of Nanolamellar WS2 and MoS2 as Additives to Lubricants Mon, 13 Oct 2014 09:34:09 +0000 http://www.hindawi.com/journals/jnm/2014/865839/ This work was aimed at studying the tribological properties of nanolamellar tungsten and molybdenum disulfides produced from nanosized W and Mo nanopowders by self-propagating high-temperature synthesis. The prepared WS2 and MoS2 powders were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential thermal analysis (DTA). For tribological tests, oil-based lubricants added with nanolamellar tungsten and molybdenum disulfides were prepared. The tribological tests show that the friction coefficient of the nanolamellar powders is lower than that of commercial powder and 0.064, resp.). It is also found that the oil-based lubricants with nanolamellar disulfide additives display higher antifriction and antiwear properties compared to commercial powder. Vladimir An, Yuri Irtegov, and Charles de Izarra Copyright © 2014 Vladimir An et al. All rights reserved. Hydrogenated Microstructure and Its Hydrogenation Properties: A Density Functional Theory Study Mon, 13 Oct 2014 09:07:49 +0000 http://www.hindawi.com/journals/jnm/2014/749804/ The relationship between microstructure and hydrogenation properties of the mixed metals has been investigated via different spectroscopic techniques and the density functional theory (DFT). FESEM and TEM analyses demonstrated the nano-grains of Mg2NiH4 and MgH2 on the hydrogenated microstructure of the adsorbents that were confirmed by using XPS analysis technique. SAED pattern of hydrogenated metals attributed the polycrystalline nature of mixed metals and ensured the hydrogenation to Mg2NiH4 and MgH2 compounds. Flower-like rough surface of mixed metals showed high hydrogenation capacity. The density functional theory (DFT) predicted hydrogenation properties; enthalpy and entropy changes of hydrogenated microstructure of MgH2 and Mg2NiH4 are −62.90 kJ/mol, −158 J/mol·K and −52.78 kJ/mol, −166 J/mol·K, respectively. The investigation corresponds to the hydrogen adsorption feasibility, reversible range hydrogenation thermodynamics, and hydrogen desorption energy of 54.72 kJ/mol. DFT predicted IR band for MgH2 and Mg2NiH4 attributed hydrogen saturation on metal surfaces. M. Abdus Salam, Bawadi Abdullah, and Suriati Sufian Copyright © 2014 M. Abdus Salam et al. All rights reserved. Synthesis and Physicochemical Behaviour of Polyurethane-Multiwalled Carbon Nanotubes Nanocomposites Based on Renewable Castor Oil Polyols Mon, 13 Oct 2014 09:03:04 +0000 http://www.hindawi.com/journals/jnm/2014/564384/ Polyurethanes (PUs) are high performance materials, with vast industrial and engineering applications. In this research, effects of Multiwalled Carbon Nanotubes (MWCNTs) on physicochemical properties of Castor Oil based Polyurethanes (COPUs) were studied. MWCNTs were added in different weight percentages (0% to 1% wt) in a castor oil based polyurethane (COPUs-MWCNTs) nanocomposites. The composition, structure, and morphology of polyurethanes were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), and element detection by energy dispersive spectroscopy (EDX) analysis, respectively. Thermal stability was studied by thermogravimetric analysis (TGA). Barrier properties and surface area studies were investigated by nitrogen permeability machine and BET technique. Mechanical properties were calculated by tensile universal testing machine. Results showed well dispersed MWCNTs in polyurethane matrix at different weight percentages. The best results were obtained with 0.3 wt% of MWCNTs in the composite. Surface area studies revealed presence of very few pores which is in a good agreement with barrier permeability, reduced up to ~68% in 1 wt% and ~70% in 0.5 wt% of MWCNTs in polymer matrix, with respect to pure COPUs samples. Alaa Ali, Kamal Yusoh, and S. F. Hasany Copyright © 2014 Alaa Ali et al. All rights reserved. Shape-Controlled Generation of Gold Nanoparticles Assisted by Dual-Molecules: The Development of Hydrogen Peroxide and Oxidase-Based Biosensors Mon, 13 Oct 2014 08:53:44 +0000 http://www.hindawi.com/journals/jnm/2014/576082/ With the assist of dual-molecules, 2-(N-morpholino)ethanesulfonic acid (MES) and sodium citrate, gold nanoparticles (GNPs) with different shapes can be generated in the H2O2-mediated reduction of chloroauric acid. This one-pot reaction can be employed to sensitively detect H2O2, probe substrates or enzymes in oxidase-based reactions as well as prepare branched GNPs controllably. By the “naked eye,” 20 μM H2O2, 0.1 μM glucose, and 0.26 U/mL catalase could be differentiated, respectively. By spectrophotometer, the detected limits of H2O2, glucose, and catalase were 1.0 μM, 0.01 μM, and 0.03 U/mL, respectively, and the detection linear ranges for them were 5.0–400 μM, 0.01–0.3 mM, and 0.03–0.78 U/mL, respectively. The proposed “dual-molecules assist” strategy probably paves a new way for the fabrication of nanosensors based on the growth of anisotropic metal nanoparticles, and the developed catalase sensor can probably be utilized to fabricate ultrasensitive ELISA methods for various analytes. Chifang Peng, Xiaohui Duan, Zhengjun Xie, and Chunli Liu Copyright © 2014 Chifang Peng et al. All rights reserved. Optimizing the Dispersion Conditions of SWCNTs in Aqueous Solution of Surfactants and Organic Solvents Mon, 13 Oct 2014 08:25:51 +0000 http://www.hindawi.com/journals/jnm/2014/102621/ The optimum concentration of surfactants in aqueous medium and the optimum sonication time for organic medium to achieve the best dispersion of SWCNTs are investigated in this study. Scanning electron microscope (SEM), atomic force microscope (AFM), and UV-vis-NIR study show that the optimum surfactant concentrations to achieve best dispersion for 0.25 mg/mL of SWCNTs are 9-10 mg/mL for (sodium dodecylbenzenesulfonate (SDBS)) and 8-9 mg/mL for (sodium deoxycholate (DOC)). The diameter of the SWCNT lies between 0.7 and 2.5 nm in the case of aqueous solvent, which is in good agreement with the chirality. Moreover, SEM analysis reveals the presence of well-dispersed nanotubes along with some amount of surfactant particles; that is, some nanotubes might be covered with surfactants. Best dispersion of SWCNTs in organic solvents (1,2-Dichloroethane (DCE) and N,N-Dimethylformamide (DMF)) is achieved by four hours of tip sonication. It realized that organic solvents provide pure SWCNTs after drying, which may possibly have SWCNTs with intrinsic properties. Md. Mahfuzur Rahman, Hammad Younes, Navaladian Subramanian, and Amal Al Ghaferi Copyright © 2014 Md. Mahfuzur Rahman et al. All rights reserved. Facile Preparation of Optically Tailored Hybrid Nanocomposite Mon, 13 Oct 2014 08:13:44 +0000 http://www.hindawi.com/journals/jnm/2014/671670/ Lead sulfide nanoparticles (PbS NPs) have been synthesized directly in poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) semiconducting polymer by a simple low temperature method. Hybrid solutions with different concentrations of PbS with respect to the polymer have been prepared and characterized first in solution and then as thin film nanocomposites deposited on quartz substrates by spin coating. Quenching of photoluminescence emission is observed both in solutions and thin films when the ratio of PbS NPs increases with respect to the polymer, suggesting the occurrence of Dexter energy transfer from the polymer to the PbS NPs. Optical absorption is markedly increased for hybrid solutions compared to pure polymer. In thin nanocomposite films an enhancement of absorbance is observed with increasing PbS NPs concentration, which is more pronounced below 400 nm. The reported results could lead to the development of a method for tailoring the optical response of devices based on PbS NP-polymer nanocomposite by controlling the PbS NP concentration inside the polymer matrix. Susana Fernández de Ávila, J. C. Ferrer, J. L. Alonso, R. Mallavia, and B. Rakkaa Copyright © 2014 Susana Fernández de Ávila et al. All rights reserved. Fabrication of Gold Nanodot Array for the Localized Surface Plasmon Resonance Mon, 13 Oct 2014 08:03:24 +0000 http://www.hindawi.com/journals/jnm/2014/175670/ Localized surface plasmon resonance (LSPR) is a promising method for detecting antigen-antibody binding in label-free biosensors. In this study, the fabrication of a LSPR substrate with a gold nanodot array through the lift-off process of an alumina mask is reported. The substrate showed an extinction peak in its extinction spectrum, and the peak position was dependent on the height of the gold nanodot array, and the change of extinction peak with the height could be predicted by the numerical simulation. In addition, the peak position was observed to be red-shifted with the increasing RIU value of the medium surrounding the gold nanodot array. In particular, the peak position in the 10 nm thick gold nanodot array was approximately 710 nm in air, and the sensitivity, defined as the ratio of the shift of peak position to the RIU of the medium, was 323.6 nm/RIU. The fabrication procedure could be applied to fabricate the LSPR substrates with a large area. Young Min Bae, Kyeong-Hee Lee, Jeongwon Yang, and Duchang Heo Copyright © 2014 Young Min Bae et al. All rights reserved. The Phase and Morphology of Cu2ZnSnSe4 Nanopowders by Hydrothermal Method Mon, 13 Oct 2014 07:09:17 +0000 http://www.hindawi.com/journals/jnm/2014/910639/ Quaternary compound Cu2ZnSnSe4 (CTZSe) which belonged to I2-II-IV-VI4 group, without rare elements, can be considered as the perfect material for absorbing layer in eco-friendly solar cells due to low cost and high efficiency. The CTZSe powders were synthesized by hydrothermal coreduction method from metal chlorides and SeO2 with reducing agent hydrazine hydrate at 160~200°C. The phases of obtained products were analyzed by X-ray diffraction (XRD) and the size and morphology were observed by field emission scanning electron microscope (FESEM). Experimental results show that well crystallized Cu2ZnSnSe4 powders without Se impurities can be obtained by reacting at 200°C for 90 h. The three strong XRD peaks of these products are corresponding to (112), (204), and (312) crystal planes, respectively. The morphologies of these products mostly show irregular polygon flakes with about 30~40 nm thickness and 50~200 nm diameters. Kegao Liu, Nianjing Ji, Ludan Shi, and Hong Liu Copyright © 2014 Kegao Liu et al. All rights reserved. To Evaluate the Application of Alkoxide Sol-Gel Method in Fabrication of 3YSZ-MWCNTs Nanocomposites, in an Attempt to Improve Its Mechanical Properties Sun, 12 Oct 2014 09:41:11 +0000 http://www.hindawi.com/journals/jnm/2014/867367/ In the present research work, fabrication of YSZ-CNTs composite system through alkoxide sol-gel processing was evaluated, in an attempt to improve its mechanical properties. Nanocomposites containing 0.5–2 wt% MWCNTs were then fabricated through the hydrolysis and condensation processing of the solution mixtures containing alkoxide and inorganic precursors along with the functionalized CNTs under basic condition and its final sintering by the SPS technique at 1400°C. Results showed the formation of a nanocomposite powder based on pure 3YSZ matrix, with well dispersion of CNTs and its good adhesion to the matrix particles in composite containing 0.5 wt% CNTs. The fracture toughness of sintered samples showed around 24% increase for the composite containing 0.5 wt% CNTs. The fracture toughness, hardness, and density decreased due to the agglomeration of CNTs over 0.5 wt%. Toughening mechanisms including pullout and crack bridging were observed on the polished and fractured surfaces. Ali Ahmadi, Amir Ali Youzbashi, Ahmad Nozad Golikand, Toraj Ebadzadeh, and Amir Maghsoudipour Copyright © 2014 Ali Ahmadi et al. All rights reserved. Evaluation of Degradation in Nanofilled Adhesive Resins Using Quantitative Light-Induced Fluorescence Mon, 22 Sep 2014 00:00:00 +0000 http://www.hindawi.com/journals/jnm/2014/671205/ The aim of this study was to evaluate degradation in commercial dental nanofilled adhesive resins using quantitative light-induced fluorescence (QLF). Three adhesives were selected: D/E resin (DR), Single Bond Plus (SB), and G-Bond (GB). The adhesives were mixed with porphyrin for the QLF analysis. Specimens were prepared by dispensing blended adhesives into a flexible mold and polymerizing. Then, the QLF analysis of the specimens was done and the porphyrin values (Simple Plaque Score and ) were measured. After thermocycling of the specimens (5000 cycles, 5 to 55°C) for the degradation, the specimens were assayed by QLF again. The porphyrin values were analyzed using paired t-test at a 95% confidence level. A significant reduction in SPS was observed in all groups after thermocycling. The significantly decreased after thermocycling except area 30 of SB group. Overall, porphyrin values decreased after thermocycling which indicates that the degradation of the adhesive resins may be measured by the change of porphyrin value. The QLF method could be used to evaluate the degradation of adhesive resin. Tae-Young Park, Sun-Jae Kim, Hee-Jung Kim, Byoung-Jin Lee, Byung-Hoon Kim, Yeong-Mu Ko, and Jeong-Bum Min Copyright © 2014 Tae-Young Park et al. All rights reserved. Improvement of Short-Circuit Current Density in p-O:Li/n-Si Heterojunction Solar Cells by Wet Chemical Etching Sun, 21 Sep 2014 11:01:11 +0000 http://www.hindawi.com/journals/jnm/2014/104136/ This study confirms that the surface texturation of window layer (Al-Y codoped ZnO) etched by diluted HCl effectively increases conversion efficiency of p-O:Li/n-Si heterojunction solar cells. The results show that the short circuit current density ( ) of cell etched at 10 s increases about 8.5% compared to unetched cell, which also corresponds to the increase of efficient photoelectric conversion in NIR region as shown in external quantum efficiency spectra. It is attributed to the increase of light transmittance of AZOY thin films in the NIR region and the effective light path of the NIR wavelength, which results in increasing of light absorption in the base layer. Feng-Hao Hsu, Na-Fu Wang, Yu-Zen Tsai, Ming-Hao Chien, and Mau-Phon Houng Copyright © 2014 Feng-Hao Hsu et al. All rights reserved.