ISRN Nanomaterials http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Correlation between Structure and Dielectric Breakdown in LDPE/HDPE/Clay Nanocomposites Wed, 19 Mar 2014 08:07:33 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2014/612154/ Cross-linked polyethylene (XLPE) is commonly used in medium/high voltage insulation due to its excellent dielectric properties and acceptable thermomechanical properties. To improve both electrical and thermal properties to a point that would possibly avoid the need for crosslinking, nanoclay fillers can be added to polymer matrix to form nanocomposites materials. In this paper, PE/clay nanocomposites were processed by mixing a commercially available premixed polyethylene/O-MMT masterbatch into a polyethylene blend matrix containing 80 wt% low density polyethylene LDPE and 20 wt% high density polyethylene HDPE with and without compatibilizer using a corotating twin-screw extruder. Various characterization techniques were employed in this paper, including optical microscopy, AFM, TEM, TGA, DMTA, and dielectric breakdown measurements in order to understand the correlation between structure and short-term dielectric breakdown strength. B. Zazoum, E. David, and A. D. Ngô Copyright © 2014 B. Zazoum et al. All rights reserved. Effect of Growth Temperature on Structural Quality of In-Rich Alloys on Si (111) Substrate by RF-MOMBE Sun, 23 Feb 2014 13:57:40 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2014/980206/ In-rich InAlN films were grown directly on Si (111) substrate by RF-MOMBE without any buffer layer. InAlN films were grown at various substrate temperatures in the range of 460–540°C with TMIn/TMAl ~3.3. Structural properties of InAlN ternary alloys were investigated with X-ray diffraction, scanning electron microscopy, and transmission electron microscopy (TEM). It is shown that the deposited In0.8AlM0.2N (0001) films can be in epitaxy with Si (111) substrate with orientation relationship of //. Also, the growth rate around ~0.25 μm/h almost remains constant for growth in the temperature range from 460 to 520°C. Cross-sectional TEM from InAlN grown on Si (111) at 460°C shows that the epitaxial film is in direct contact with Si without any interlayer. Wei-Chun Chen, Yue-Han Wu, Jr.-Sheng Tian, Tzu-Chun Yen, Pei-Yin Lin, Jr-Yu Chen, Chien-Nan Hsiao, and Li Chang Copyright © 2014 Wei-Chun Chen et al. All rights reserved. Carbon Nanotube Electron Sources: From Electron Beams to Energy Conversion and Optophononics Wed, 05 Feb 2014 09:32:52 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2014/879827/ Carbon nanotubes have a host of properties that make them excellent candidates for electron emitters. A significant amount of research has been conducted on nanotube-based field-emitters over the past two decades, and they have been investigated for devices ranging from flat-panel displays to vacuum tubes and electron microscopes. Other electron emission mechanisms from carbon nanotubes, such as photoemission, secondary emission, and thermionic emission, have also been studied, although to a lesser degree than field-emission. This paper presents an overview of the topic, with emphasis on these less-explored mechanisms, although field-emission is also discussed. We will see that not only is electron emission from nanotubes promising for electron-source applications, but also its study could reveal unusual phenomena and open the door to new devices that are not directly related to electron beams. Alireza Nojeh Copyright © 2014 Alireza Nojeh. All rights reserved. Optical Absorption in Nano-Structures: Classical and Quantum Models Sun, 29 Dec 2013 14:31:51 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/504341/ In the last decade, nano-structured materials have gained a significant interest for applications in solar cells and other optical and opto-electronic devices. Due to carrier confinement, the absorption characteristics in these structures are quite different from the absorption in bulk materials and thin films. Optical absorption coefficients of a silicon nano-wire are obtained based on a semi-classical model where the photon-electron interaction is described by the interaction of an electromagnetic wave with the electrons in the valence band of a semiconductor. The absorption characteristics showed enhanced optical absorption but no resonant peaks. In our modified model, we have identified optically active inter band transitions by performing electronic structure calculations on unit cells of nano-dimensions. The absorption spectrum obtained here shows explicit excitonic processes. This absorption is tunable from the visible region to near UV portion of the solar spectrum. In our previous work on thin films (100 nm) of ITO, we have used classical Drude model to describe free electron absorption. Using the imaginary part of the calculated complex dielectric function, we have plotted the absorption coefficient versus wavelength of the photon and compared with the experimental data showing good agreement between theory and experiment. Anand Kulkarni, Durdu Guney, and Ankit Vora Copyright © 2013 Anand Kulkarni et al. All rights reserved. Temperature Effects on the Crystallization and Coarsening of Nano-CeO2 Powders Thu, 19 Dec 2013 15:18:55 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/208614/ The effect of temperature on nano-CeO2 particle coarsening is investigated. The nanoceria powders were synthesized using the microemulsion method and then exposed to temperatures in the range of 373–1273 K. It was found that the nanoparticles exhibited a strong tendency to form agglomerates and through the application of ultrasound these agglomerates could be broken into smaller sizes. In addition average nanoparticle sizes were determined by powder X-ray diffraction (XRD). The outcome of this work indicates that the initial nano-CeO2 powders are amorphous in nature. Annealing promotes CeO2 crystallization and a slight shift in the (111) XRD intensity peaks corresponding to CeO2. Moreover, at temperatures below 773 K, grain growth in nano-CeO2 particles is rather slow. Apparently, mass transport through diffusional processes is not likely to occur as indicated by an estimated activation energy of 20 kJ/mol. At temperatures above 873 K, the measured activation energy shifted to 105 kJ/mol suggesting a possible transition to Ostwald-Ripening type mass transport mechanisms. H. F. Lopez and H. Mendoza Copyright © 2013 H. F. Lopez and H. Mendoza. All rights reserved. Electronic Nose Based on Nanomaterials: Issues, Challenges, and Prospects Tue, 19 Nov 2013 09:34:58 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/941581/ The ability to precisely control the morphology and dimension coupled with the tunable surface reactivity has led to the widespread investigation of nanomaterials for various device applications. The associated high surface area to volume ratio implies that large numbers of atom are residing on the surface and are available for interaction. Accordingly, nanomaterials have demonstrated the potential to realize sensors with ultrahigh sensitivities and fast response kinetics. The smaller size further provides the possibility of miniaturization and integration of large number of devices. All these properties makes them an attractive candidate for the fabrication of electronic nose or e-nose. E-nose is an intelligent chemical-array sensor system that mimics the mammalian olfactory system. The present paper critically reviews the recent development in the field of nanomaterials based e-nose devices. In particular, this paper is focused on the description of nanomaterials for e-nose application, specifically on the promising approaches that are going to contribute towards the further development of this field. Various issues related to successful utilization of different nanomaterials for commercial application are discussed, taking help from the literature. The review concludes by briefing the important steps taken towards the commercialization and highlighting the loopholes that are still to be addressed. Niranjan S. Ramgir Copyright © 2013 Niranjan S. Ramgir. All rights reserved. Biosynthesis of Silver Chloride Nanoparticles Using Bacillus subtilis MTCC 3053 and Assessment of Its Antifungal Activity Sun, 17 Nov 2013 14:20:43 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/317963/ The present investigation reported the synthesis of silver chloride nanoparticles using Bacillus subtilis. The adsorption of colloidal silver chloride nanoparticles showed an intense peak at the wavelength of 400 nm after 20 hrs of biomass incubation. The size of the silver nanoparticles ranges from 20 to 60 nm which was obtained from transmission electron microscope (TEM). The X-ray diffraction (XRD) pattern confirmed the crystalline nature of the nanoparticles. The bright circular spots of selected diffraction area (SAED) pattern also confirmed the good crystalline nature of the silver chloride nanoparticles with high magnification of TEM images. The presence of nitrate reductase enzyme in the cellular membrane of B. subtilis was confirmed by sodium dodecyl (SDS) polyacrylamide gel electrophoresis and it was found that the molecular weight is 37 kDa. The possible functional groups of the reductase enzyme in B. subtilis were identified by Fourier transform infrared spectroscopy (FTIR). Finally, antifungal activity of silver chloride nanoparticle was examined against Candida albicans, Aspergillus niger, and Aspergillus flavus. We conclude that the synthesis of silver chloride nanoparticles using microorganisms is more economical and simple. The antifungal property of silver chloride nanoparticles will play a beneficial role in biomedical nanotechnology. Kanniah Paulkumar, Shanmugam Rajeshkumar, Gnanadhas Gnanajobitha, Mahendran Vanaja, Chelladurai Malarkodi, and Gurusamy Annadurai Copyright © 2013 Kanniah Paulkumar et al. All rights reserved. Texture of GaAs Nanoparticles Deposited by Pulsed Laser Ablation in Different Atmospheres Thu, 31 Oct 2013 14:32:14 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/576506/ This work analyzes the effect of nanosecond laser pulse deposition of GaAs in an inert atmosphere of Ar and He. The number of pulses and the gas pressure were varied and the effect on the nanoparticles formation was studied by scanning electron microscopy, grazing incidence small angle X-ray scattering, and atomic force microscopy. It is shown that the GaAs nanoparticle sizes and size distributions can be controlled partly by the number of laser pulses applied during their production and partly by the choice of inert gas and its pressure. Our results suggest that He is a more promising working gas producing narrower size distributions and a better size control of the grown nanoparticles. P. Dubček, B. Pivac, S. Milošević, N. Krstulović, Z. Kregar, and S. Bernstorff Copyright © 2013 P. Dubček et al. All rights reserved. Large Area C60 Film Obtained by Microwave Oven Irradiation from an Organic Resin Sun, 27 Oct 2013 09:39:13 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/524548/ In the present work the synthesis of fullerene thin film produced in a conventional microwave oven from the decomposition of terpenoid is reported. The polycrystalline structure of the sample was determined by X-ray diffraction (XRD); the sample showed several phases, and the main phase corresponds to fullerene ordered in a face-centered cubic structure (FCC), with a lattice parameter  Å, with two more structures: one is orthorhombic system with lattice parameters  Å,  Å, and  Å, and the other is the monoclinic system with lattice parameters  Å,  Å,  Å, and ° coexisting also with graphite 2H phase with lattice parameters  Å,  Å. It was observed in a scanning electron microscopy (SEM) that the sample formed thin films of stacked carbon. The film thickness was measured by a SEM, and it was 140.8 to 523 nm and the macroscopic area of 12 cm2, whereas a high-resolution transmission electron microscopy (HRTEM) revealed that the main phase of the material is C60 ordered in a face-centered cubic structure (FCC). In the sample surface by atomic force microscopy (AFM), islands deposited crystals were observed having symmetry m crystal habit associated with the tetrahedron. J. Martínez-Reyes, L. G. Díaz Barriga-Arceo, L. Rendón-Vazquez, R. Martínez-Guerrero, N. Romero-Parada, E. Palacios-González, V. Garibay-Febles, and J. Ortíz-López Copyright © 2013 J. Martínez-Reyes et al. All rights reserved. Ag Nanoparticles: Experimental Study of Sign Identification of Nonlinear Refractive Index by Moiré Deflectometry and Z-Scan Methods Mon, 21 Oct 2013 15:22:21 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/327575/ Two different methods are presented for the sign identification of nonlinear refractive index () of Ag colloidal nanoparticles which are based on nonscanning Moiré deflectometry and Z-scan. In the Moiré deflectometry setup, two lasers are used, one is used as pump laser which causes thermal nonlinear effects in the sample, and the second one is used as the probe laser for monitoring these effects by Moiré deflectometry system. By observing the deflected Moiré fringes, we can determine the sign of nonlinear refractive index in real time, and there would be no need for calibration or complicated calculations. The second technique for sign identification is Z-scan. In this technique, a CW 532 nm second harmonic Nd:YAG laser with a beam power of 55 mW is used as the excitation source. Results show that the nonlinear refractive index is negative for Ag nanoparticles in pure water by both methods. Adeleh Granmayeh Rad, Khosro Madanipour, and Ata Koohian Copyright © 2013 Adeleh Granmayeh Rad et al. All rights reserved. The 3D Kuramoto-Sivashinsky Equation for Nonequilibrium Defects Interacting through Self-Consisting Strain and Nanostructuring of Solids Mon, 21 Oct 2013 09:55:27 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/981616/ It is shown that the bulk defect-deformational (DD) nanostructuring of isotropic solids can be described by a closed three-dimensional (3D) nonlinear DD equation of the Kuramoto-Sivashinsry (KS) type for the nonequilibrium defect concentration, derived here in the framework of the nonlocal elasticity theory (NET). The solution to the linearized DDKS equation describes the threshold appearance of the periodic self-consistent strain modulation accompanied by the simultaneous formation of defect piles at extremes of the strain. The period and growth rate of DD nanostructure are determined. Based on the obtained results, a novel mechanism of nanostructuring of solids under the severe plastic deformation (SPD), stressing the role of defects generation and selforganization, described by the DDKS, is proposed. Theoretical dependencies of nanograin size on temperature and shear strain reproduce well corresponding critical dependencies obtained in experiments on nanostructuring of metals under the SPD, including the effect of saturation of nanofragmentation. The scaling parameter of the NET is estimated and shown to determine the limiting small grain size. V. I. Emel’yanov Copyright © 2013 V. I. Emel’yanov. All rights reserved. Development of Magnetic Nanoparticles for Cancer Gene Therapy: A Comprehensive Review Thu, 10 Oct 2013 15:52:31 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/646284/ Since they were first proposed as nonviral transfection agents for their gene-carrying capacity, magnetic nanoparticles have been studied thoroughly, both in vitro and in vivo. Great effort has been made to manufacture biocompatible magnetic nanoparticles for use in the theragnosis of cancer and other diseases. Here we survey recent advances in the study of magnetic nanoparticles, as well as the polymers and other coating layers currently available for gene therapy, their synthesis, and bioconjugation processes. In addition, we review several gene therapy models based on magnetic nanoparticles. Vladimir Mulens, María del Puerto Morales, and Domingo F. Barber Copyright © 2013 Vladimir Mulens et al. All rights reserved. Synthesis, Characterization, and Applications of Dendrimer-Encapsulated Zero-Valent Ni Nanoparticles as Antimicrobial Agents Thu, 03 Oct 2013 09:56:47 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/843709/ Dendrimers have emerged as one of the most promising, cost-effective synthesizing methodologies in which highly monodispersed metallic nanoparticles can be produced with varied chemical functionalities. In this report, we have investigated the synthesis and application of as-synthesized dendrimer-encapsulated zero-valent nickel “Ni(0)” nanoparticles (NPs), using a fourth generation (G4) NH2-terminated poly(amido)amine (PAMAM) dendrimer as the host template, as potential antimicrobial agents. Apparently, based on ultraviolet visible spectroscopy (UV-vis) and transmission electron microscopy (TEM) analyses, Ni(0) NPs with an average measured size less than 10 nm in diameter were formed within the interior void cavity of the dendrimer structure. X-ray diffraction (XRD) analysis indicates that the NPs exhibited a single-phased, face-centered-cubic (fcc) crystallographic structure. Furthermore, to evaluate the antimicrobial activity of the dendrimer-encapsulated Ni(0) NPs, disk diffusion assay and minimum inhibitory concentration (MIC) examinations, both antimicrobial tests, were conducted. Subsequently, UV-vis analyses, after exposure of the dendrimer-encapsulated Ni(0) NPs to both Gram-negative and Gram-positive bacteria, revealed that the dendrimer-encapsulated particles prevented the growth of bacteria during the culturing stage. A. Mazumder, J. Davis, V. Rangari, and M. Curry Copyright © 2013 A. Mazumder et al. All rights reserved. Nanobiosensors: Concepts and Variations Thu, 03 Oct 2013 08:52:32 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/327435/ Biosensing has been one of the hottest topic attracting scientific minds since long back. It is so as biological entities are very complex and are directly associated with the existence of a healthy environment. The design of biosensors also has witnessed significant changes in the recent past. Biosensors for applications as diverse as food quality estimation, environmental monitoring, and diagnosis of clinical and metabolic complications have come to the fore. Nanotechnology has bestowed some highly exciting ingredients for the improvement of sensing phenomenon. The use of diverse nanomaterials ranging from nanoparticles, nanotubes, nanorods, and nanowires has enabled faster detection and its reproducibility in a much better way. The unique properties of nanomaterials such as high electrical conductivity, better shock bearing ability, and the sensitive responses such as piezoelectric and versatile color based detection mechanisms are only the results of congregation of nanomaterial properties. This paper highlights the different types of biosensors based on different types of nanomaterials and their developmental and implicational aspects. Parth Malik, Varun Katyal, Vibhuti Malik, Archana Asatkar, Gajendra Inwati, and Tapan K. Mukherjee Copyright © 2013 Parth Malik et al. All rights reserved. Controlled Geometry Formation of the Carbon Coils by the Substrate Pretreatment Tue, 17 Sep 2013 11:08:57 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/893636/ Carbon coils could be synthesized using C2H2/H2 as source gases and SF6 as an incorporated additive gas under thermal chemical vapor deposition system. Prior to the carbon coils deposition reaction, the supporting substrates were pretreated using various methods. Among the methods, the thermal etching pretreatment of Ni-SiO2 substrate with SF6 leads to the exclusive formation of the nanosized carbon coils. The diamond powders pretreatment of Si substrate gives rise to the dominant formation of the microsized carbon coils after 10 minutes reaction time. The geometry selectivity for the carbon coils in a specific pretreatment method was discussed in association with the peeled-off Ni layers by the thermal etching pretreatment with SF6 and the remained carbon particles on Si substrate by the diamond powders pretreatment. Semi Park and Sung-Hoon Kim Copyright © 2013 Semi Park and Sung-Hoon Kim. All rights reserved. Harmful Impact of ZnS Nanoparticles on Daphnia sp. in the Western Part (Districts of Bankura and Purulia) of West Bengal, India Mon, 16 Sep 2013 11:18:53 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/207239/ ZnS nanoparticles of different sizes are synthesized employing a simple wet chemical method. These nanoparticles are used to study their impact on the Daphnia sp. through traditional toxicity tests. The percentage of mortality is found to increase initially with increasing nanoparticle concentration or exposure time and is finally found to saturate for higher concentrations or exposure times. Mortality is found to be higher for smaller particles. Hopping frequency and heart rate are also found to increase with increasing nanoparticle exposure time for a fixed nanoparticle concentration. These observations can be attributed to the enhanced surface photooxidation property of the ZnS nanoparticles. Thus the present study will help people to understand the hitherto unknown harmful impact of ZnS nanoparticles on aquatic organisms in the western part of West Bengal (Bankura and Purulia districts), India. Baibaswata Bhattacharjee, Nilanjana Chatterjee, and Chung-Hsin Lu Copyright © 2013 Baibaswata Bhattacharjee et al. All rights reserved. Should Experimental Chemists Be Doing More to Help Evaluate the Toxicological Potential of Nanoparticles? Wed, 28 Aug 2013 13:10:16 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/801242/ More general testing of nanoparticles (NP) for properties that are amenable towards biological activity, and thus potentially conducive to nanotoxicity, should be conducted on a broader scale by experimental chemists to help assess the pernicious threat that NP may present to human health or to the environment. For example, evaluation by measuring NP-biomolecule bioaffinity using techniques such as mass spectrometry (MS) and nuclear magnetic resonance (NMR) is advocated, thereby echoing a similar call to computational and theoretical chemists to expand their studies and make at least part of their work, where feasible, relevant to nanotoxicity. Karel D. Klika Copyright © 2013 Karel D. Klika. All rights reserved. Analysis of the Behavior of Carbon Nanotubes on Cementitious Composites Tue, 27 Aug 2013 15:22:23 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/415403/ Nanotechnology has brought significant innovations in science and engineering. Carbon nanotube has been considered a new and outstanding material in nanoscience field with great potential application in the construction industry. The main objective of this study is to analyze the behavior of cementitious materials produced with the insertion of carbon nanotubes of multiple walls in different concentrations and compare their physic-mechanical properties with plain mortar. This research covers the examination of nanoscale cement products and the use of carbon nanotubes to increase the strength and durability of cementitious composites. Three different ratios of carbon nanotubes have been searched: 0.20, 0.40, and 0.60%. To evaluate the mechanical properties of the samples, destructive and nondestructive tests were carried out to obtain compressive strength, tensile strength by diametrical compression, and dynamic modulus of elasticity as well as to determine their deformation properties. Methods of instrumentation such as scanning electron microscopy and porosity were also used in the analysis of microstructure of the materials. The study presents graphs, tables, and figures describing the behavior of CNT added to mortars samples, allowing a better understanding of the use of this new material in the construction industry. Jorge Fernandes de Morais, Assed Naked Haddad, and Laia Haurie Copyright © 2013 Jorge Fernandes de Morais et al. All rights reserved. Nanocrystalline Cellulose as Effect Pigment in Clear Coatings for Wood Tue, 27 Aug 2013 14:52:57 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/930236/ Nanocrystalline cellulose (CNC) is a renewable material with high potential in many applications. Due to its unique self-assembly and optical properties, CNC tends to behave as an iridescent pigment. The aim of this research was to explore the potential of CNC as an effect pigment in wood coatings. CNC-based coatings were developed from an aqueous CNC solution, a UV-curable water-based clear coating formulation, several colorants, and specialized additives. In this paper, the morphology of the resulting CNC films was investigated through circular dichroism and optical microscopy under polarized light. The effect of the CNC surface charge changes was monitored through zeta potential measurements. Color changes, or travel, and flop index were used to assess the iridescent effect of the coatings containing CNC. The experimental wood coatings contained CNC showed that the enhancement of the iridescent effect depends on the distribution and alignment of the CNC rod-like particles in order to generate the right pitch in the helical structure and their interaction with the polymer matrix as well with the additives. In conclusion, CNC could be successfully used as effect pigment in finishing systems, which can enhance the attractiveness and bring out the special grain of various types of wood. Mirela Simona Vlad-Cristea, Véronic Landry, Pierre Blanchet, and Claudiane Ouellet-Plamondon Copyright © 2013 Mirela Simona Vlad-Cristea et al. All rights reserved. Fabrication of Aluminium Nanowires by Differential Pressure Injection Mon, 26 Aug 2013 12:46:35 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/132798/ The reported study aims to demonstrate the application of a simple technique, which is referred to as pressure differential injection, to prepare metallic nanowires. This technique relies on the difference in pressure between the inside of sealed nanochannels of an anodic aluminium oxide (AAO) substrate and the ambient atmosphere to inject a molten metal, which is previously deposited on the substrate, into the AAO pores. The application of this technique enabled the fabrication of nanowires in aluminium with diameters comprised between 55 nm and 65 nm. A. Hashoosh, H. Hirshy, E. B. Brousseau, and A. Moosa Copyright © 2013 A. Hashoosh et al. All rights reserved. Carbon Nanotubes Synthesis via Arc Discharge with a Yttria Catalyst Tue, 20 Aug 2013 08:27:06 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/785160/ A facile method is proposed to use a computer controlled Arc discharge gap between graphite electrodes together with an yttria-nickel catalyst to synthesize carbon nanotubes under an Ar-H2 gases mixture atmosphere by applying different DC currents and pressure. This produces carbon nanotubes with decreased diameters and increased length. XRD evidence indicated a shift toward higher crystallinity nanotubes. Yields of the CNTs after purification were also enhanced. M. I. Mohammad, Ahmed A. Moosa, J. H. Potgieter, and Mustafa K. Ismael Copyright © 2013 M. I. Mohammad et al. All rights reserved. Screening of Most Effective Variables for Development of Gastroretentive Mucoadhesive Nanoparticles by Taguchi Design Wed, 07 Aug 2013 12:04:49 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/348095/ The objective of this study was the selection of the most influential variable for the preparation of gastroretentive mucoadhesive nanoparticles of acyclovir. Nanoparticles were prepared by one-step desolvation method; effect of formulation and processing variables on various response variables were studied by a Taguchi standard orthogonal array L8 design. Independent variables studied were the amount of gelatin, amount of glutaraldehyde, amount of Pluronic F-68, acetone addition rate, pH, stirring time, and stirring speed. The dependent variables studied were the particle size, polydispersity index, amount of drug released in 6 h, time required to release 60% of drug, entrapment efficiency, loading efficiency, and mucoadhesiveness. The size of all nanoparticulate formulations prepared as per the experimental design (Taguchi screening design) varied between 165 and 1610 nm, PDI between 0.360 and 1.00, bioadhesiveness between 3.959 and 11.02 g, cumulative percent drug release in 24 h between 40.74 and 72.48, entrapment efficiency between 15.70 and 83.12, and loading efficiency between 39.72 and 80.49. Pareto ranking analyses showed that the two most important factors affecting the selected responses were amount of gelatin and amount of Pluronic F-68 (). Ankit Anand Kharia and Akhlesh Kumar Singhai Copyright © 2013 Ankit Anand Kharia and Akhlesh Kumar Singhai. All rights reserved. Preparation and Characterization of Nanocrystalline CuS Thin Films for Dye-Sensitized Solar cells Tue, 06 Aug 2013 08:20:27 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/829430/ A dye-sensitized nanocrystalline copper sulphide (CuS) solar cell is developed using crystal violet (CV) as a photosensitizer. Nanocrystalline CuS thin film is deposited on indium tin oxide- (ITO-) coated glass substrate by chemical bath deposition (CBD) technique. These thin films are characterized for their structural, optical and electrical properties using X-ray diffractometer (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Optical absorbance measurements from UV-visible spectrometer at normal incidence of light in the wavelength range of 320–1100 nm and current-voltage (I-V) measurements were also made. The deposited CuS thin film on ITO-coated glass substrate may be used as a photo electrode in the fabrication of dye-sensitized solar cell (DSSC). The carbon soot collected on the substrate is used as a counter electrode. The counter electrode coupled with a dye-sensitized CuS thin film along with a redox electrolyte mixture is used to develop a complete photovoltaic cell. The fill factor and efficiency were evaluated for the developed DSSC. M. A. Sangamesha, K. Pushpalatha, G. L. Shekar, and S. Shamsundar Copyright © 2013 M. A. Sangamesha et al. All rights reserved. X-Ray Spectral Investigation of Carbon Nanocapsule and Graphite Nanosheet Electronic Structures Tue, 06 Aug 2013 08:09:21 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/940545/ Ultrasoft X-ray emission spectroscopy (USXES) was used to investigate the electronic structures of FePt alloy included carbon nanocapsules (FePt@CNCs) and graphite nanosheets (GNSs). These materials were synthesized by electric plasma discharge in an ultrasonic cavitation field of liquid ethanol. Scanning and transmission electron microscopies were used to study the spatial structures and morphologies. The electronic structure of GNSs was compared with that of reference synthetic graphite powder and high surface area reduced graphene oxide (RGO) sheets with an average thickness of one graphene layer. Investigations of the electronic structures of the FePt@CNC and GNS mixture and GNSs obtained after magnetic separation of the mixture revealed that GNS graphene layers exhibited a smaller curvature than those of carbon nanocapsules, which widened the -subband of GNSs due to overlapping of the orbitals. Thicker GNSs had a narrower CKα emission band than RGO sheets, which was related to the greater overlapping of and orbitals in the more crumpled and corrugated RGO sheets. Bogdan Ilkiv, Svitlana Petrovska, Ruslan Sergiienko, Etsuro Shibata, Takashi Nakamura, and Yaroslav Zaulychnyy Copyright © 2013 Bogdan Ilkiv et al. All rights reserved. Preparation of AgI/Silica/Poly(Ethylene Glycol) Nanoparticle Colloid Solution and X-Ray Imaging Using It Tue, 30 Jul 2013 10:36:25 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/670402/ This work performed X-ray imaging of mouse by using aqueous colloid solution of AgI nanoparticles coated with silica (AgI/SiO2) and then surface-modified with poly(ethylene glycol) (PEG) (AgI/SiO2/PEG). A colloid solution of AgI nanoparticles was prepared by mixing silver perchlorate and potassium iodide in water. The AgI nanoparticles were surface-modified with 3-mercaptopropyltrimethoxysilane and then were silica-coated by a sol-gel reaction between tetraethylorthosilicate and H2O catalyzed with NaOH in ethanol. The AgI/SiO2 particle surface was modified with PEG by using methoxy PEG silane . The AgI/SiO2/PEG colloid solution revealed a computed tomography value as high as 1343.6 HU at an iodine concentration of 0.1 M, which was higher than a commercial X-ray contrast agent with the same iodine concentration. Tissues of mouse could be imaged by injecting the concentrated colloid solution into them. Yoshio Kobayashi, Tetsuya Ayame, Tomohiko Nakagawa, Yohsuke Kubota, Kohsuke Gonda, and Noriaki Ohuchi Copyright © 2013 Yoshio Kobayashi et al. All rights reserved. Change of Electrophysical Properties of Nanocrystalline SiC Films by Laser Treatment at Applied Electric Field Thu, 25 Jul 2013 11:13:02 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/810394/ Studied are peculiarities of the changes in the structure and electrophysical properties of nanocrystalline silicon carbide films of 3C-SiC polytype subjected to the action of picosecond laser pulses with λ = 355 nm and a pulse power up to 1.5 W. It is established that laser processing of the films with an energy density of 3 × 10−2−30 J/cm2 leads to ablation without decomposition of SiC. During the laser processing the electrical resistance of the films rises due to diminution of the film thickness. While measuring the PL properties of nc-SiC films under the influence of the applied electric field with intensity 3 × 103 V/cm, the effect of a single triple enhancement of the luminescence maximum is revealed. Repeated PL measurements at the same area of the film under the applied electric field with the intensity ranging from 0 to 1 × 104 V/cm show that the PL emission intensity diminishes at the short-wavelength boundary of the maximum and rises at the long-wavelength boundary. Thereat the spectral position of the PL maximum remains unchanged. A. V. Semenov, V. M. Puzikov, P. V. Mateichenko, and V. Romano Copyright © 2013 A. V. Semenov et al. All rights reserved. Wagner-Vengrenovich Distribution Thu, 20 Jun 2013 18:00:59 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/651576/ The process of coarsening of nanoclusters or nanocrystals (NCs) is investigated for the case when cluster growth (dissolution) is governed simultaneously by both diffusion along dislocation pipes and the rate of formation of chemical connections (chemical reaction) at cluster surface, namely, Wagner’s growing mechanism. For that, the total flow of atoms to (from) a cluster is represented by two parts, namely, diffusion part and the Wagner (kinetic) one. The dependence of the rate of growth of NC on the ratio of the parts of the total flow has been determined as well as the NC’s size distribution function referred to as the Wagner-Vengrenovich distribution. Computed distribution is compared with experimentally obtained histograms. Bohdan V. Ivanskii, Anatolii V. Moskalyuk, Sergey V. Yarema, Igor I. Panko, and Miroslav O. Stasyk Copyright © 2013 Bohdan V. Ivanskii et al. All rights reserved. Mesoporous SiO2-Supported Pt Nanoparticles for Catalytic Application Sun, 10 Mar 2013 15:54:05 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/745397/ SiO2 nanoparticles have been synthesized by combining Stober’s method and nonsurfactant process. The diameters and pore sizes can be controlled by altering the template and its concentration. Mesoporous SiO2 obtained this way has extremely large surface area compared with most oxide supports, which benefits the catalytic performance. Pt nanoparticles were in situ grown on and in mesoporous SiO2 nanoparticles with low amount of the metal and high load ratio. Furthermore, we firstly developed a novel route, called “one-pot” method, to prepare Pt/SiO2 catalyst where mesoporous silica preparing and Pt loading occurred in one step. This method is more efficient in saving reagent, since it can prevent Pt loss. In the meantime, it enables the template to reduce agent. The catalytic activity of Pt/SiO2 samples was measured by CO oxidation. It is indicated that the supporting silica with mesopores is more active than silica with micropores. Yingze Cao, Wentao Zhai, Xiang Zhang, Shuxi Li, Lin Feng, and Yen Wei Copyright © 2013 Yingze Cao et al. All rights reserved. Hydrogen Storage of a Fixed Bed of Nanocrystalline Mixed Oxides Mon, 04 Mar 2013 15:18:46 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2013/539534/ Nanocrystalline hydrotalcite derived mixed oxides containing magnesium, cobalt, and aluminum (MCAM) (M(1−x)AlxO(1+x/2); M = Mg or Co/Mg and Co and x = molar ratios) have been synthesized successfully and showed reversible hydrogen storage capacity at near ambient condition using fixed bed. ICP-MS and XRD analysis confirmed the adsorbent phases and their homogeneity. Adsorbent morphology and textural properties have been characterized using FESEM, BET and TEM analysis techniques. Nano-crystalline and porous mixed oxides exhibited 3 wt% H2 storage capacity and desorbed 57% of adsorbed H2. Spillover phenomena are observed through FTIR analysis. Adsorption enthalpy () and entropy () change were −25.58 kJ/mol and −59.98 J/mol·K, respectively, which implied a prospective feature of reversible hydrogen adsorption on nano-crystalline mixed oxide. M. Abdus Salam, Suriati Sufian, Ye Lwin, and T. Murugesan Copyright © 2013 M. Abdus Salam et al. All rights reserved. The Self-Healing Capability of Carbon Fibre Composite Structures Subjected to Hypervelocity Impacts Simulating Orbital Space Debris Sun, 30 Dec 2012 08:05:42 +0000 http://www.hindawi.com/journals/isrn.nanomaterials/2012/351205/ The presence in the space of micrometeoroids and orbital debris, particularly in the lower earth orbit, presents a continuous hazard to orbiting satellites, spacecrafts, and the international space station. Space debris includes all nonfunctional, man-made objects and fragments. As the population of debris continues to grow, the probability of collisions that could lead to potential damage will consequently increase. This work addresses a short review of the space debris “challenge” and reports on our recent results obtained on the application of self-healing composite materials on impacted composite structures used in space. Self healing materials were blends of microcapsules containing mainly various combinations of a 5-ethylidene-2-norbornene (5E2N) and dicyclopentadiene (DCPD) monomers, reacted with ruthenium Grubbs' catalyst. The self healing materials were then mixed with a resin epoxy and single-walled carbon nanotubes (SWNTs) using vacuum centrifuging technique. The obtained nanocomposites were infused into the layers of woven carbon fibers reinforced polymer (CFRP). The CFRP specimens were then subjected to hypervelocity impact conditions—prevailing in the space environment—using a home-made implosion-driven hypervelocity launcher. The different self-healing capabilities were determined and the SWNT contribution was discussed with respect to the experimental parameters. B. Aïssa, K. Tagziria, E. Haddad, W. Jamroz, J. Loiseau, A. Higgins, M. Asgar-Khan, S. V. Hoa, P. G. Merle, D. Therriault, and F. Rosei Copyright © 2012 B. Aïssa et al. All rights reserved.