Journal of Nanomaterials The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. Synthesis, Structural Characterization, and Thermal Properties of the Poly(methylmethacrylate)/δ-FeOOH Hybrid Material: An Experimental and Theoretical Study Mon, 08 Feb 2016 08:34:59 +0000 The δ-FeOOH/PMMA nanocomposites with 0.5 and 2.5 wt.% of δ-FeOOH were prepared by grafting 3-(trimethoxysilyl)propyl methacrylate on the surface of the iron oxyhydroxide particles. The FTIR spectra of the δ-FeOOH/PMMA nanocomposites showed that the silane monomers were covalently attached to the δ-FeOOH particles. Because of the strong interaction between the PMMA and δ-FeOOH nanoparticles, the thermal stability of the δ-FeOOH/PMMA nanocomposites was improved compared to the pure PMMA. The SEM analysis conferred the size agglomerate of particles regarding the morphology of samples. The theoretical study enabled a better understanding of the interaction of the polymer with the iron oxyhydroxide. The DFT-based calculations reinforce the radical trapping mechanism of stabilization of nanocomposites; that is, Fe3+ species might be able to accept electrons coming from the organic phase that decomposes via radical unzipping. The radical scavenge effect delays the weight loss of polymer. Silviana Corrêa, Lívia C. T. Lacerda, Maíra dos S. Pires, Marcus V. J. Rocha, Francisco G. E. Nogueira, Adilson C. da Silva, Marcio C. Pereira, Angela D. B. de Brito, Elaine F. F. da Cunha, and Teodorico C. Ramalho Copyright © 2016 Silviana Corrêa et al. All rights reserved. Aging Thermal Treatment in the Inconel 725 Brazed Incorporating Tungsten Nanoparticles Mon, 08 Feb 2016 06:57:24 +0000 Fractures in blade sections of Inconel 725 were impregnated with tungsten nanoparticles and jointed by the brazing process. In order to evaluate their effect over the microstructure, aging thermal treatments at 750°C for 2, 6, 10, and 14 h were done. BNi-9 was selected as brazing filler metal and was characterized by scanning electron microscopy and X-ray fluorescence. Before brazing, the fractures were impregnated with a mixture of tungsten NPs in ethanol. Measurements of Vickers microhardness showed an increase in the melting zone of samples with aging thermal treatment for 14 h, which is attributed to the precipitation of the γ′ phase with a typical size of ca. 100 nm. Likewise, the tungsten NPs modified the size and morphology of Cr-Ni eutectics into finer and uniformly distributed microstructures. H. M. Hdz-García, R. Muñoz-Arroyo, A. I. Martinez, M. A. González, E. E. Granda-Gutiérrez, J. L. Acevedo-Dávila, M. Castro-Roman, and F. García-Vázquez Copyright © 2016 H. M. Hdz-García et al. All rights reserved. Gold Nanorods-Based Theranostics for Simultaneous Fluorescence/Two-Photon Luminescence Imaging and Synergistic Phototherapies Sun, 07 Feb 2016 14:09:22 +0000 Gold nanorods (GNRs) have shown great potential applications in cancer theranostics due to the unique phenomenon of surface plasmon resonance, which leads to strong electric fields on the surface and consequently enhances the absorption and scattering in the near-infrared (NIR) region. Indocyanine green (ICG), an amphipathic dye, is not only an excellent NIR imaging agent but also an ideal light absorber for laser-mediated photodynamic and photothermal therapy. In this study, in order to integrate the merits of GNRs and ICG in biomedical applications, we developed ICG conjugated silica-coated GNRs (GNR@SiO2-ICG) for cancer imaging and phototherapy. The covalent coupling strategy reduces the probability of leakage/desorption during the delivery. The as-prepared GNR@SiO2-ICG could serve as efficient probes to simultaneously enhance fluorescence (FL) imaging and two-photon luminescence (TPL) imaging. In vitro experiments indicated that A375 cells could be killed through synergistic phototherapies effect of GNRs and ICG using single wavelength continuous-wave laser irradiation. Our results indicated that the synthesized GNR@SiO2-ICG are effective for simultaneously enhancing FL/TPL imaging and synergistic phototherapies. Shan Fang, Chunxiao Li, Jing Lin, Haigang Zhu, Daxiang Cui, Yunsheng Xu, and Zhiming Li Copyright © 2016 Shan Fang et al. All rights reserved. Hybrid Films Based on a Bridged Silsesquioxane Doped with Goethite and Montmorillonite Nanoparticles as Sorbents of Wastewater Contaminants Sun, 07 Feb 2016 08:57:14 +0000 The synthesis and characterization of silsesquioxane (SSO) films with pendant dodecyl groups and doped with goethite (Gt) or montmorillonite (MMT) nanoparticles were carried out and the new materials tested as sorbents of diverse contaminants. The synthetic method used yielded SSO films with the inorganic substrates homogeneously distributed within the polymeric matrices. The new materials were characterized by SEM, FTIR, XRD, and DSC and tested to evaluate their capability for adsorbing metallic cations, organic dyes, and phosphate, frequent contaminants of industrial effluents. All films were found suitable for removing metallic cations. Results also showed that the SSO films undoped and doped with Gt are primarily apt for anionic compounds removal. Although the SSO films doped with MMT are capable of removing cationic contaminants from aqueous samples, the stiffness of the SSO matrix hinders MMT properties as an adsorbent. The possibility of dispersing nanoparticulate systems in the stable and chemically inert SSO matrices simplifies their application for contaminant removal, particularly because it makes the separation process of the absorbed pollutant from the treated medium easier. Carolina V. Waiman, Ignacio E. dell’Erba, Carlos A. Chesta, and María Lorena Gómez Copyright © 2016 Carolina V. Waiman et al. All rights reserved. Demonstration of Improved Charge Transfer in Graphene/Au Nanorods Plasmonic Hybrids Stabilized by Benzyl Thiol Linkers Sun, 07 Feb 2016 07:22:12 +0000 Hybrids based on graphene decorated with plasmonic gold (Au) nanostructures are being investigated as possible materials combination to add to graphene functionalities of tunable plasmon resonance and enhanced absorption at selected wavelength in the visible-near-infrared region of the spectrum. Here, we report a solution drop-casting approach for fabricating stable hybrids based on chemical vapor deposition (CVD) graphene and Au nanorods, which are able to activate effective charge transfer from graphene. We demonstrate that CVD graphene functionalization by benzyl thiol (BZT) provides the linker to strong anchoring, via S-Au bonds, Au nanorods to graphene. Optical measurements by spectroscopic ellipsometry give evidence of the introduction of plasmon resonances at 1.85 and 2.25 eV in the Au nanorods/BZT/graphene hybrids, which enable surface enhanced Raman scattering (SERS) detection. Furthermore, an effective electron transfer from graphene to Au nanorods, resulting in an enhancement of p-type doping of graphene with a consequent decrease of its sheet resistance, is probed by Raman spectroscopy and corroborated by electrical measurements. Giuseppe Valerio Bianco, Maria Michela Giangregorio, Maria Losurdo, Alberto Sacchetti, Pio Capezzuto, and Giovanni Bruno Copyright © 2016 Giuseppe Valerio Bianco et al. All rights reserved. Certain Aspects of Silver and Silver Nanoparticles in Wound Care: A Minireview Thu, 04 Feb 2016 06:39:35 +0000 Resistance to antimicrobial agents by pathogenic bacteria has emerged in recent years and is a major health problem. In this context silver and silver nanoparticles (AgNP) have been known to have inhibitory and bactericidal effects and was used throughout history for treatment of skin ulcer, bone fracture, and supporting wound healing. In all of these applications prevention and treatment of bacterial colonized/infected wounds are critical. In this context silver and its derivatives play an important role in health care. Silver is widely used in clinical practice in the form of silver nitrate and/or silver sulfadiazine. In the last few years silver nanoparticles entered into clinical practice as both antimicrobial and antifungal agents. In addition, nanosilver is used in coating medical devices (catheters) and as component of wound dressings. In this paper we present summarized information about silver and nanoparticles made of silver in the context of their useful properties, especially antibacterial ones, being of a great interest for researchers and clinicians. Marek Konop, Tatsiana Damps, Aleksandra Misicka, and Lidia Rudnicka Copyright © 2016 Marek Konop et al. All rights reserved. Simulation of Effective Slip and Drag in Pressure-Driven Flow on Superhydrophobic Surfaces Wed, 03 Feb 2016 08:15:32 +0000 The flow on superhydrophobic surfaces was investigated using finite element modeling (FEM). Surfaces with different textures like grooves, square pillars, and cylinders immersed in liquid forming Cassie state were modeled. Nonslip boundary condition was assumed at solid-liquid interface while slip boundary condition was supposed at gas-liquid interface. It was found that the flow rate can be affected by the shape of the texture, the fraction of the gas-liquid area, the height of the channel, and the driving pressure gradient. By extracting the effective boundary slip from the flow rate based on a model, it was found that the shape of the textures and the fraction of the gas-liquid area affect the effective slip significantly while the height of the channel and the driving pressure gradient have no obvious effect on effective slip. Yuanding Huang, Xuezeng Zhao, Yunlu Pan, and Khurshid Ahmad Copyright © 2016 Yuanding Huang et al. All rights reserved. Optical Band Gap and Thermal Diffusivity of Polypyrrole-Nanoparticles Decorated Reduced Graphene Oxide Nanocomposite Layer Tue, 02 Feb 2016 08:03:13 +0000 A polypyrrole-nanoparticles reduced graphene oxide nanocomposite layer was prepared using electrochemical method. The prepared samples were characterized using Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and UV-visible spectroscopy. The band gap of nanocomposite layers was calculated from UV-visible spectra and the thermal diffusivity of layers was measured using a photoacoustic technique. As experimental results, the optical band gap was in the range between 3.580 eV and 3.853 eV, and thermal diffusivity was increased with increasing the layer thickness from 2.873 cm2/s to 12.446 cm2/s. Amir Reza Sadrolhosseini, Suraya Abdul Rashid, A. S. M. Noor, Alireza Kharazmi, H. N. Lim, and Mohd. Adzir Mahdi Copyright © 2016 Amir Reza Sadrolhosseini et al. All rights reserved. Stainless Steel Mesh Supported Carbon Nanofibers for Electrode in Bioelectrochemical System Mon, 01 Feb 2016 13:33:13 +0000 We proposed a self-connected carbon nanofiber design for electrode in microbial bioelectrochemical system. This design was realized by direct growth of carbon nanofibers (CNFs) onto stainless steel (SSM) via a chemical vapor deposition process without addition of any external catalysts. In the CNFs-SSM composite electrode, the SSM acted as the conductive network and ensured efficient substrate and proton transfer, and the CNFs layer served as highly porous habitats for thick biofilm propagation. The current generated by the CNFs-SSM was 200 times higher than the bare SSM under the same experimental conditions. This provided a simple and promising method for preparation of electrode material with high performance and low-cost in bioelectrochemical system. Jing Wang, Ming Li, Fangtai Liu, and Shuiliang Chen Copyright © 2016 Jing Wang et al. All rights reserved. Facile Method for Preparation of Silica Coated Monodisperse Superparamagnetic Microspheres Mon, 01 Feb 2016 09:59:12 +0000 This paper presents a facile method for preparation of silica coated monodisperse superparamagnetic microsphere. Herein, monodisperse porous polystyrene-divinylbenzene microbeads were prepared by seeded emulsion polymerization and subsequently sulfonated with acetic acid/H2SO4. The as-prepared sulfonated macroporous beads were magnetized in presence of Fe2+/Fe3+ under alkaline condition and were subjected to silica coating by sol-gel process, providing water compatibility, easily modifiable surface form, and chemical stability. FE-SEM, TEM, FT-IR, and TGA were employed to characterize the silica coated monodisperse magnetic beads (~7.5 μm). The proposed monodisperse magnetic beads can be used as mobile solid phase particles candidate for protein and DNA separation. Xuan-Hung Pham, San Kyeong, Jaein Jang, Hyung-Mo Kim, Jaehi Kim, Seunho Jung, Yoon-Sik Lee, Bong-Hyun Jun, and Woo-Jae Chung Copyright © 2016 Xuan-Hung Pham et al. All rights reserved. Reinforcement of Multiwalled Carbon Nanotube in Nitrile Rubber: In Comparison with Carbon Black, Conductive Carbon Black, and Precipitated Silica Sun, 31 Jan 2016 11:04:54 +0000 The properties of nitrile rubber (NBR) reinforced by multiwalled carbon nanotube (MWCNT), conductive carbon black (CCB), carbon black (CB), and precipitated silica (PSi) were investigated via viscoelastic behavior, bound rubber content, electrical properties, cross-link density, and mechanical properties. The filler content was varied from 0 to 15 phr. MWCNT shows the greatest magnitude of reinforcement considered in terms of tensile strength, modulus, hardness, and abrasion resistance followed by CCB, CB, and PSi. The MWCNT filled system also exhibits extremely high levels of filler network and trapped rubber even at relatively low loading (5 phr) leading to high electrical properties and poor dynamic mechanical properties. Although CCB possesses the highest specific surface area, it gives lower level of filler network than MWCNT and also gives the highest elongation at break among all fillers. Both CB and PSi show comparable degree of reinforcement which is considerably lower than CCB and MWCNT. Atip Boonbumrung, Pongdhorn Sae-oui, and Chakrit Sirisinha Copyright © 2016 Atip Boonbumrung et al. All rights reserved. Adsorptive Removal of Acid Blue 80 Dye from Aqueous Solutions by Cu-TiO2 Thu, 28 Jan 2016 16:44:32 +0000 The adsorption performance of a Cu-TiO2 composite for removing acid blue 80 (AB80) dye from aqueous solutions was investigated in terms of kinetics, equilibrium, and thermodynamics. The effect of operating variables, such as solution pH, initial dye concentration, contact time, and temperature, on AB80 adsorption was studied in batch experiments. AB80 adsorption increased with increasing contact time, initial dye concentration, and temperature and with decreasing solution pH. Modeling of adsorption kinetics showed good agreement of experimental data with the pseudo-second-order kinetics model. The experimental equilibrium data for AB80 adsorption were evaluated for compliance with different two-parameter, three-parameter, and four-parameter isotherm models. The Langmuir isotherm model best described the AB80 adsorption equilibrium data. The thermodynamic data revealed that the AB80 adsorption process was endothermic and nonspontaneous. Kinetics, equilibrium, and thermodynamic results indicate that Cu-TiO2 adsorbs AB80 by a chemical sorption reaction. Ingrid Johanna Puentes-Cárdenas, Griselda Ma. Chávez-Camarillo, César Mateo Flores-Ortiz, María del Carmen Cristiani-Urbina, Alma Rosa Netzahuatl-Muñoz, Juan Carlos Salcedo-Reyes, Aura Marina Pedroza-Rodríguez, and Eliseo Cristiani-Urbina Copyright © 2016 Ingrid Johanna Puentes-Cárdenas et al. All rights reserved. Modified Sol-Gel Synthesis of Carbon Nanotubes Supported Titania Composites with Enhanced Visible Light Induced Photocatalytic Activity Thu, 28 Jan 2016 11:49:20 +0000 Multiwalled carbon nanotube (MWCNT) enhanced MWCNT/TiO2 nanocomposites were synthesized by surface coating of carbon nanotube with mixed phase of anatase and rutile TiO2 through a modified sol-gel approach using tetrabutyl titanate as raw material. The morphological structures and physicochemical properties of the nanocomposites were characterized by FT-IR, XRD, DTA-TG, TEM, and UV-Vis spectra. The results show that TiO2 nanoparticles with size of around 15 nm are closely attached on the sidewall of MWCNT. The nanocomposites possess good absorption properties not only in the ultraviolet but also in the visible light region. Under irradiation of ultraviolet lamp, the prepared composites have the highest photodegradation efficiency of 83% within 4 hours towards the degradation of Methyl Orange (MO) aqueous solution. The results indicate that the carbon nanotubes supported TiO2 nanocomposites exhibit high photocatalytic activity and stability, showing great potentials in the treatment of wastewater. Quanjie Wang, Yanqing Wang, Baorong Duan, and Mengmeng Zhang Copyright © 2016 Quanjie Wang et al. All rights reserved. Light-Regulated Release of Entrapped Drugs from Photoresponsive Gold Nanoparticles Thu, 28 Jan 2016 10:39:46 +0000 Release of a payload in a spatiotemporal fashion has a substantial impact on increasing therapeutic efficacy. In this work, a novel monolayer of gold nanoparticles (AuNPs) featuring light-responsive ligands was investigated as a potential drug carrier whose drug release can be triggered by UV light. Hydrophobic molecules were noncovalently entrapped in the compartments of its monolayers. Once irradiated with UV light, the dinitrobenzyl linker was cleaved, leading to release of the entrapped agent. AuNPs were characterized using UV spectrophotometry, TEM, and a zetasizer. A naturally occurring compound extracted from Goniothalamus elegans Ast was chosen as a hydrophobic model drug. Entrapment and release of dye were monitored using fluorimetry. The percent encapsulation of dye was of 13.53%. Entrapped dye can be released upon UV irradiation and can be regulated by changing irradiation time. Up to % entrapped dye can be released after irradiation for 20 minutes. In the absence of UV light, dye release was only 19.75%. For comparison purposes, AuNPs having no dinitrobenzyl groups showed a minimal release of 12.23% and 11.69% with and without UV light, respectively. This demonstrated an alternative strategy to encapsulate drugs using a noncovalent approach followed by their controlled release upon UV irradiation. Kaniknun Sreejivungsa, Nattawut Suchaichit, Panawan Moosophon, and Apiwat Chompoosor Copyright © 2016 Kaniknun Sreejivungsa et al. All rights reserved. DNA Microspheres Coated with Bioavailable Polymer as an Efficient Gene Expression Agent in Yeasts Wed, 27 Jan 2016 07:01:49 +0000 Gene delivery is one of the steps necessary for gene therapy and for genetic modification. However, delivering DNA into cells is challenging due to its negative charge that leads to repulsion by the negative cell membrane. In the current research, DNA spheres with a DNA encoding to a certain gene were coated with bioavailable polymers, polyethylene imine (PEI) and polycaprolactone (PCL), in a short, one-step sonochemical reaction. The polymers were used in order to neutralize the negative charge of the DNA. Our study shows that the DNA nanospheres not only managed to penetrate the cell without causing it any damage, but also expressed the desired gene inside it. Irena Reytblat, Anat Lipovsky, and Aharon Gedanken Copyright © 2016 Irena Reytblat et al. All rights reserved. Chemical-Vapor-Deposited Graphene as Charge Storage Layer in Flash Memory Device Tue, 26 Jan 2016 09:05:07 +0000 We demonstrated a flash memory device with chemical-vapor-deposited graphene as a charge trapping layer. It was found that the average RMS roughness of block oxide on graphene storage layer can be significantly reduced from 5.9 nm to 0.5 nm by inserting a seed metal layer, which was verified by AFM measurements. The memory window is 5.6 V for a dual sweep of ±12 V at room temperature. Moreover, a reduced hysteresis at the low temperature was observed, indicative of water molecules or −OH groups between graphene and dielectric playing an important role in memory windows. W. J. Liu, L. Chen, P. Zhou, Q. Q. Sun, H. L. Lu, S. J. Ding, and David W. Zhang Copyright © 2016 W. J. Liu et al. All rights reserved. Influence of Synthesis Route on the Radiation Sensing Properties of ZnO Nanostructures Tue, 26 Jan 2016 08:01:41 +0000 ZnO nanostructures were synthesized using two different routes and the light sensor response of structures was studied. The synthesis by carbothermal reduction resulted in ZnO tetrapods while the synthesis by microwave assisted hydrothermal method produced multipoint stars structures. Characterization by scanning and transmission electron microscopy confirmed that both structures consist of one-dimensional crystals with a hexagonal cross section and growth direction. Under a simulated solar radiation spectrum, it was observed that tetrapods display a light sensor response of approximately 5000. For the multipoint stars, a maximum in the sensor signal value of 3400 was achieved, which also represents a substantial variation in the conductivity of the material. A model based on the surface oxygen presence is proposed to explain the observed results. R. A. Silva and M. O. Orlandi Copyright © 2016 R. A. Silva and M. O. Orlandi. All rights reserved. Morphological and Rheological Characterization of Gold Nanoparticles Synthesized Using Pluronic P103 as Soft Template Sun, 24 Jan 2016 08:35:48 +0000 The synthesis of gold nanoparticles (Au-NPs), using Pluronic P103 as soft template to design tuned hybrid gold/P103 nanomaterials, is reported here. The effect of the concentration of P103 and the synthesis temperature on the growth, size, and morphology of Au-NPs were studied. The rheological properties of these hybrid nanomaterials at different measured temperatures were studied as well. By increasing the concentration of P103, the micelles progressively grew due to an increase in the number of surface cavities. These cavities came together causing large nucleation centers and developing larger Au-NPs. The synthesis temperature was varied to induce significant dehydration of the P103 micelles. Below the cloud point temperature micelles underwent distinct changes related to spherical-to-polymer-like micelles transitions. Two nanostructures were formed: (1) small Au-NPs arranged on the surface of micelles, which acted as soft templates, and (2) large and independent Au-NPs. Above the cloud point temperature, Au-NPs were related to the shape and size of the P103 micellar aggregates. Rheological measurements showed that viscosity was sensitive to the concentration of P103. Also, it was demonstrated that synthesis temperature had a considerable influence on viscosity of the produced nanomaterials. Nancy Tepale, Victor V. A. Fernández-Escamilla, Carlos Álvarez, Eric Flores-Aquino, Valeria J. González-Coronel, Daniel Cruz, and Manuel Sánchez-Cantú Copyright © 2016 Nancy Tepale et al. All rights reserved. Formation of Nanocrystallized Structure in Worn Surface Layer of T10 Steel against 20CrMnTi Steel during Dry Rubbing Thu, 21 Jan 2016 09:09:03 +0000 T10 steel slid against 20CrMnTi steel on a pin-on-disc wear test rig. Optical Microscope (OM), scanning electron microscope (SEM), and High Resolution Transmission Electron Microscope (HRTEM) methods were used to analyze the microstructures in the worn surface layers. The microstructures in the worn surface layers of pins and discs were all severely plastically deformed. Furthermore, the ultrafine and even nanoferrite structure (10 nm to 100 nm) was observed when the normal load reached 60 N. The mechanism of forming nanocrystalline structure in the sliding friction induced deformation layer (SFIDL) was elucidated as the result of the simultaneous and recursive actions of (i) severe shear deformation and (ii) friction heat on the contact surface. Xin Wang, Xicheng Wei, Jing Zhang, Rongbin Li, Meng Hua, and Wurong Wang Copyright © 2016 Xin Wang et al. All rights reserved. In Situ Detection of Trace Furfural in Aqueous Solution Based on Au Nanoparticle/Au Film Surface-Enhanced Raman Spectroscopy Wed, 20 Jan 2016 12:13:03 +0000 Furfural is an important chemical solvent and intermediate. Sensitive detection of this compound has attracted great interest in various fields. Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive method for material detection because of its optical enhancement effect of plasmonic nanostructures. This study presents a simple and versatile method to synthesize a SERS substrate, where polyaminothiophenol (PATP) was used to realize the stable combination of Au nanoparticles (AuNPs) and Au film via self-assembly. The near-field electric field distribution was calculated using the finite difference time domain (FDTD) simulation to determine the parameters responsible for electric field enhancement. The simulation results show that SERS enhanced factors are sensitive to interparticle spacing and materials for solid support but insensitive to particle size. Moreover, the experimental results show that the optimized substrates with the highest Raman activity were formed by six layers of 60 nm AuNPs decorated on a 30 nm thick Au film, thereby validating the simulation results. The SERS factor of the optimal substrates is approximately 5.57 × 103, and the in situ detection limit is 4.8 ppm. The 3D Raman spectra, relative standard deviation values for major peaks, and changes in signal intensity with time show the good reproducibility and stability of the substrates. Wei Qi, Weigen Chen, Fu Wan, Jingxin Zou, and Zhaoliang Gu Copyright © 2016 Wei Qi et al. All rights reserved. New Collagen-Dextran-Zinc Oxide Composites for Wound Dressing Tue, 19 Jan 2016 12:51:52 +0000 The goal of this paper was the design, development, and characterization of some new composites, based on collagen and dextran as natural polymers and zinc oxide as antimicrobial, to be used in wound healing. Collagen hydrogels with various concentrations of dextran and zinc oxide were investigated in terms of rheological analysis. The spongious composites, obtained by freeze-drying of hydrogels, were evaluated by morphology (SEM), water uptake, and biological (enzymatic biodegradation) analysis. All the results were strongly influenced by the nature and concentration of composite components. Based on the performances of the hydrogels, stationary rheometry, porous structure, morphology, and biological behavior, the antimicrobial spongious composite based on collagen and dextran with 50% ZnO were the most promising for future applications in wound dressing and a biomaterial with high potential in skin regeneration. Georgeta Păunica-Panea, Anton Ficai, Minodora Maria Marin, Ștefania Marin, Mădălina Georgiana Albu, Vlad Denis Constantin, Cristina Dinu-Pîrvu, Zina Vuluga, Mihai Cosmin Corobea, and Mihaela Violeta Ghica Copyright © 2016 Georgeta Păunica-Panea et al. All rights reserved. Ethylene-Octene Copolymers/Organoclay Nanocomposites: Preparation and Properties Tue, 19 Jan 2016 08:47:56 +0000 Two ethylene-octene copolymers with 17 and 45 wt.% of octene (EOC-17 and EOC-45) were compared in nanocomposites with Cloisite 93A. EOC-45 nanocomposites have a higher elongation at break. Dynamical mechanical analysis (DMA) showed a decrease of with frequency for EOC-17 nanocomposites, but decrease is followed by an increase for EOC-45 nanocomposites; DMA showed also increased modulus for all nanocomposites compared to pure copolymers over a wide temperature range. Barrier properties were improved about 100% by addition of organoclay; they were better for EOC-17 nanocomposites due to higher crystallinity. X-ray diffraction (XRD) together with transmission electron microscopy (TEM) showed some intercalation for EOC-17 but much better dispersion for EOC-45 nanocomposites. Differential scanning calorimetry (DSC) showed increased crystallization temperature for EOC-17 nanocomposite (aggregates acted as nucleation agents) but decrease for EOC-45 nanocomposite together with greatly influenced melting peak. Accelerated UV aging showed smaller C=O peak for EOC-45 nanocomposites. Alice Tesarikova, Dagmar Merinska, Jiri Kalous, and Petr Svoboda Copyright © 2016 Alice Tesarikova et al. All rights reserved. Graphene Functionalization by 1,6-Diaminohexane and Silver Nanoparticles for Water Disinfection Tue, 19 Jan 2016 08:36:30 +0000 Reduced graphene (G) was prepared by chemically reducing graphene oxide (GO). For the first time, the resulting G was functionalized by 1,6-diaminohexane and decorated with silver nanoparticles (AgNPs). The resulting G and modified G were characterized by X-ray diffraction (XRD), nuclear magnetic resonance (NMR), infrared (FTIR) spectroscopies, and high resolution transmission electron microscopy (HRTEM). The 1,6-diaminohexane-graphene structure was ascertained from the NMR and FTIR data. AgNPs were identified with various sizes within the graphene matrix. The resulting hybrid material was used as an effective antimicrobial contact catalyst for disinfecting water from Total Coliform and Fecal Coliform bacteria. A triple action in this respect was achieved from graphene, 1,6-diaminohexane, and AgNPs without observed release of silver that causes toxicity. Abdelsattar O. E. Abdelhalim, Ahmed Galal, Mohamed Z. Hussein, and Ibrahim E.-T. El Sayed Copyright © 2016 Abdelsattar O. E. Abdelhalim et al. All rights reserved. Structural and Thermal Studies of ZnS and CdS Nanoparticles in Polymer Matrices Mon, 18 Jan 2016 13:35:49 +0000 We report the synthesis and structural studies of ZnS and CdS nanoparticles in polyvinylpyrrolidone (PVP), poly(vinyl alcohol) (PVA), and poly(methyl methacrylate) (PMMA) matrices. The metal sulfides/polymer nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, electronic spectroscopy (UV-Vis), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The particle sizes as calculated from the absorption spectra were in agreement with the results obtained from TEM and XRD data. They showed metal sulfides nanoparticles in the polymers matrices with average crystallite sizes of 1.5–6.9 nm. The TGA results indicate that incorporation of the nanoparticles significantly altered the thermal properties of the respective polymers with ZnS/PVA and CdS/PVA nanocomposites displaying higher thermal stability than the other polymer nanocomposites. Jejenija Osuntokun and Peter A. Ajibade Copyright © 2016 Jejenija Osuntokun and Peter A. Ajibade. All rights reserved. Decreasing Coalbed Methane Formation Damage Using Microfoamed Drilling Fluid Stabilized by Silica Nanoparticles Mon, 18 Jan 2016 11:02:06 +0000 Coalbed methane (CBM) reservoirs in China are featured in remarkable nanosized pores below 200 nm, acknowledged natural cleats, and tectonic fractures. This paper discussed the possibility that a clay free microfoamed drilling fluid could be stabilized by silica nanoparticles (CFMDF-NP) so as to avoid formation damage of CBM drilling. In accordance with the experimental results of foaming capacity and foam stability test, basic drilling fluid performance appraisal, micromorphology observation, swelling test, and gas permeability test, the mechanism of the CFMDF-NP was discussed in this paper. The results indicated that, with 10–20 nm nano-SiO2, the foaming volume of traditional foamed drilling fluid could be improved by up to 50% and an increased half-life period by up to 200%. Chemically treated nano-SiO2 dispersions functioned as a foam stabilizer and a foaming agent as well. The CFMDF-NP had controllable density (0.7~1 g/cm3) and excellent rheological and sealing properties, which could satisfy the drilling requirements of the low pressure coal seams. With 5–8 mm slicing on the contaminated side of coal cores, the contaminated zone could be removed and the recovery rate of gas permeability could reach up to 70%. The CFMDF-NP laid good technical foundation to decrease formation damage of CBM reservoir. Jihua Cai, Sui Gu, Fawen Wang, Xianyu Yang, Ye Yue, Xiaoming Wu, and V. F. Chixotkin Copyright © 2016 Jihua Cai et al. All rights reserved. Facile Synthesis of High {001} Facets Dominated BiOCl Nanosheets and Their Selective Dye-Sensitized Photocatalytic Activity Induced by Visible Light Mon, 18 Jan 2016 08:13:02 +0000 Single-crystal BiOCl nanosheets, with high 001 facets exposed, were synthesized through a facile hydrolysis reaction under general atmospheric pressure, without adding any organic surfactant or agent. The thickness of the BiOCl nanosheets is about 20 nm, and the diameter is arranged from 200 to 400 nm. The structure of the BiOCl nanosheets was characterized by X-ray diffraction, energy disperse X-ray spectrum, transmission electron microscopy, and selective area electron diffraction. Moreover, three different dyes were used as model molecules to test the photocatalytic activity of BiOCl nanosheets under visible light. It was found that the BiOCl nanosheets possess selective photocatalytic behavior as their activity over RhB is much higher than that over MO or MB. Based on the analysis of the experimental results, the potential mechanism was discussed. Da Zhang, Liang Chen, Chengjing Xiao, Jing Feng, Lingmin Liao, Zaiqin Wang, and Tao Wei Copyright © 2016 Da Zhang et al. All rights reserved. Atomistic Tight-Binding Theory of Electron-Hole Exchange Interaction in Morphological Evolution of CdSe/ZnS Core/Shell Nanodisk to CdSe/ZnS Core/Shell Nanorod Sun, 17 Jan 2016 16:14:30 +0000 Based on the atomistic tight-binding theory (TB) and a configuration interaction (CI) description, the electron-hole exchange interaction in the morphological transformation of CdSe/ZnS core/shell nanodisk to CdSe/ZnS core/shell nanorod is described with the aim of understanding the impact of the structural shapes on the change of the electron-hole exchange interaction. Normally, the ground hole states confined in typical CdSe/ZnS core/shell nanocrystals are of heavy hole-like character. However, the atomistic tight-binding theory shows that a transition of the ground hole states from heavy hole-like to light hole-like contribution with the increasing aspect ratios of the CdSe/ZnS core/shell nanostructures is recognized. According to the change in the ground-state hole characters, the electron-hole exchange interaction is also significantly altered. To do so, optical band gaps, ground-state electron character, ground-state hole character, oscillation strengths, ground-state coulomb energies, ground-state exchange energies, and dark-bright (DB) excitonic splitting (stoke shift) are numerically demonstrated. These atomistic computations obviously show the sensitivity with the aspect ratios. Finally, the alteration in the hole character has a prominent effect on dark-bright (DB) excitonic splitting. Worasak Sukkabot Copyright © 2016 Worasak Sukkabot. All rights reserved. Particle Size Dependent Photodynamic Anticancer Activity of Hematoporphyrin-Conjugated Fe3O4 Particles Sun, 17 Jan 2016 13:48:41 +0000 Nanomedicine, which involves the use of magnetic nanoparticles such as Fe3O4, has provided novel technical solutions for cancer diagnosis and treatment. Most studies in nanomedicine have focused on the use of nanoparticles with magnetic resonance imaging and hyperthermia. However, to achieve optimum anticancer effects, it is important to understand the physicochemical properties of magnetic nanoparticles and their interactions with biological entities. In this study, we synthesized Fe3O4 particles of various sizes and conjugated them with hematoporphyrin (HP) molecules by using a simple surface-modification method. HP molecules were covalently bound to the surface of Fe3O4 particles by a wet chemical process, resulting in Fe3O4@HPs particles that were uniform in size, were nontoxic, and exhibited strong anticancer effects on human prostate cancer (PC-3) and breast cancer (MDA-MB-231) cell lines. The Fe3O4@HPs particles showed remarkable and efficient photodynamic anticancer activity, depending on their particle size. These results indicate that all size of Fe3O4@HPs particles can be useful for photodynamic anticancer therapy, although the smaller size is better than the larger size and further studies will be needed to confirm the potential for clinical anticancer treatment. Ki Chang Nam, Kyong-Hoon Choi, Kyu-Dong Lee, Jung Hyun Kim, Jin-Seung Jung, and Bong Joo Park Copyright © 2016 Ki Chang Nam et al. All rights reserved. Quantitative Imaging and In Situ Concentration Measurements of Quantum Dot Nanomaterials in Variably Saturated Porous Media Sun, 17 Jan 2016 12:43:27 +0000 Knowledge of the fate and transport of nanoparticles in the subsurface environment is limited, as techniques to monitor and visualize the transport and distribution of nanoparticles in porous media and measure their in situ concentrations are lacking. To address these issues, we have developed a light transmission and fluorescence method to visualize and measure in situ concentrations of quantum dot (QD) nanoparticles in variably saturated environments. Calibration cells filled with sand as porous medium and various known water saturation levels and QD concentrations were prepared. By measuring the intensity of the light transmitted through porous media exposed to fluorescent light and by measuring the hue of the light emitted by the QDs under UV light exposure, we obtained simultaneously in situ measurements of water saturation and QD nanoparticle concentrations with high spatial and temporal resolutions. Water saturation was directly proportional to the light intensity. A linear relationship was observed between hue-intensity ratio values and QD concentrations for constant water saturation levels. The advantages and limitations of the light transmission and fluorescence method as well as its implications for visualizing and measuring in situ concentrations of QDs nanoparticles in the subsurface environment are discussed. Burcu Uyuşur, Preston T. Snee, Chunyan Li, and Christophe J. G. Darnault Copyright © 2016 Burcu Uyuşur et al. All rights reserved. Effect of Solvent, Dye-Loading Time, and Dye Choice on the Performance of Dye-Sensitized Solar Cells Sun, 17 Jan 2016 10:49:45 +0000 Anatase titania films with a thickness of up to 20 μm and deposited over a fluorine-doped tin-oxide substrate are impregnated with ruthenium dyes N-719 and N-749 using Dip and supercritical-fluid methods for the purpose of fabricating dye-sensitized solar cell devices. The dyes are dissolved in different solvent mixtures, including supercritical carbon dioxide, as well as combinations of more traditional solvents including mixtures of acetonitrile, and t-butanol. Analytical studies included thin-film analyzing and scanning electron microscopy to measure titania film thickness and porosity, UV-Vis spectroscopy to quantify dye concentration, and current-voltage device characterizations to assess energy conversion efficiency, as well as open-circuit voltage decay measurements and quantum efficiency to examine electron collection efficiency. A significant result is that using the dye N-749 in a solvent that includes supercritical carbon dioxide leads to energy conversion efficiencies that are higher for devices with a thick 20 μm semiconductor film than for the case of devices with thinner films, including the 10 μm film thickness that is traditionally considered an upper threshold. The supercritical-fluid method for the N-719 dye also enabled shorter impregnation duration than more conventional classical Dip Methods. Fahd M. Rajab Copyright © 2016 Fahd M. Rajab. All rights reserved.