Journal of Nanomaterials The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Continuous Synthesis of Ag/TiO2 Nanoparticles with Enhanced Photocatalytic Activity by Pulsed Laser Ablation Thu, 16 Nov 2017 10:59:55 +0000 A facile and environmental friendly synthesis strategy based on pulsed laser ablation has been developed for potential mass production of Ag-loaded TiO2 (Ag/TiO2) nanoparticles. By sequentially irradiating titanium and silver target substrates, respectively, with the same 1064 nm 100 ns fiber laser, Ag/TiO2 particles can be fabricated. A postannealing process leads to the crystallization of TiO2 to anatase phase with high photocatalytic activity. The phase composition, microstructure, and surface state of the elaborated Ag/TiO2 are characterized by X-ray diffraction (XRD), energy dispersive X-ray (EDX), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS) techniques. The results suggest that the presence of silver clusters deposited on the surface of TiO2 nanoparticles. The nanostructure is formed through laser interaction with materials. Photocatalytic activity evaluation shows that silver clusters could significantly enhance the photocatalytic activity of TiO2 in degradation of methylene blue (MB) under UV light irradiation, which is attributed to the efficient electron traps by Ag clusters. Our developed Ag/TiO2 nanoparticles synthesized via a straightforward, continuous, and green pathway could have great potential applications in photocatalysis. Rui Zhou, Shengdong Lin, Huixin Zong, Tingting Huang, Fengping Li, Jiahong Pan, and Jingqin Cui Copyright © 2017 Rui Zhou et al. All rights reserved. Synthesis of a High-Coercivity FePt–Ag Nanocomposite Magnet via Block Copolymer-Templated Self-Assembly Wed, 15 Nov 2017 00:00:00 +0000 Magnetic recording media are composed of magnetic thin films consisting of magnetically isolated crystallites. For practical use of magnetic particles as recording media, it will be necessary to realize high coercivity by fabricating nanocrystalline grains and forming grain boundaries with the nonmagnetic phase. In this study, a high-coercivity FePt–Ag nanocomposite magnet was synthesized by means of block copolymer-templated self-assembly. Precursors of Fe, Pt, and Ag were introduced into a polymer block, and the resulting material was oxidized and then reduced to form a nanocomposite consisting of FePt nanoparticles surrounded by a matrix of Ag. X-ray diffraction analysis revealed that the introduction of Ag did not significantly affect the crystalline ordering of the FePt. The addition of Ag increased the coercivity by 53% (from 11.1 to 17.0 kOe). Our results suggest that the grain boundaries of the nonmagnetic Ag metal acted as pinning sites, disrupting magnetic coupling between individual FePt nanocrystallites and hindering domain wall motion at an external magnetic field. Hiroaki Wakayama and Hirotaka Yonekura Copyright © 2017 Hiroaki Wakayama and Hirotaka Yonekura. All rights reserved. Effect of Gas Flowrate on Nucleation Mechanism of MWCNTs for a Compound Catalyst Tue, 14 Nov 2017 10:19:54 +0000 Activation of the catalyst particles during a CVD process can be anticipated from the carbon feeding rate. In this study, Fe2O3/Al2O3 catalyst was synthesized with uniformly dispersed iron over alumina support for onward production of multiwalled carbon nanotubes (MWCNTs) in a fluidized bed chemical CVD reactor. The effect of the ethylene flowrate on catalytic activity of the compound catalyst and morphology of the as-grown MWCNTs was also investigated in this study. The dispersed active phases of the catalyst and optimized gas flowrate helped in improving the tube morphology and prevented the aggregation of the as-grown MWCNTs. The flowrates, below 100 sccm, did not provide sufficient reactants to interact with the catalyst for production of defect-free CNT structures. Above 100 sccm, concentration of the carbon precursor did not show notable influence on decomposition rate of the gas molecules. The most promising results on growth and structural properties of MWCNTs were gained at ethylene flowrate of 100 sccm. At this flowrate, the ratio of and intensity peaks () was deliberated about 1.40, which indicates the growth of graphitic structures of MWCNTs. S. Shukrullah, N. M. Mohamed, Y. Khan, M. Y. Naz, A. Ghaffar, and I. Ahmad Copyright © 2017 S. Shukrullah et al. All rights reserved. Characterization of the Spindle Morphology Nanomicelles Assembled from Sericin and Gelatin Tue, 14 Nov 2017 07:24:11 +0000 Complex nanomicelles were prepared by sericin and type A gelatin with molecular weight of 5789 Da and 128664 Da separately. The assembling conditions were as follows: mass ratio (sericin/gelatin) was 1 : 1, protein concentration was 0.5%, temperature was 35°C, and assembling time was 18 hours. Scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), and dynamic light scattering (DLS) were conducted to observe and characterize the complex nanomicelles. Results showed that the complex sericin/gelatin micelles was a kind of nanospindle micelles. The micelles had high electrochemical stability, thermal stability, antidilution stability, and storage stability. Xiaozhou Su, Lei Li, and Weihan Huang Copyright © 2017 Xiaozhou Su et al. All rights reserved. SnO2 Nanoparticles Decorated 2D Wavy Hierarchical Carbon Nanowalls with Enhanced Photoelectrochemical Performance Tue, 14 Nov 2017 00:00:00 +0000 Two-dimensional carbon nanowall (2D-CNW) structures were prepared by hot wire assisted plasma enhanced chemical vapor deposition (hw-PECVD) system on silicon substrates. Controlled variations in the film structure were observed with increase in applied rf power during deposition which has been established to increase the rate of dissociation of precursor gases. The structural changes resulted in the formation of wavy-like features on the 2D-CNW, thus further enhancing the surface area of the nanostructures. The FESEM results confirmed the morphology transformation and conclusively showed the evolution of the 2D-CNW novel structures while Raman results revealed increase in ratio indicating increase in the presence of disordered domains due to the presence of open edges on the 2D-CNW structures. Subsequently, the best 2D-CNW based on the morphology and structural properties was functionalized with tin oxide (SnO2) nanoparticles and used as a working electrode in a photoelectrochemical (PEC) measurement system. Intriguingly, the SnO2 functionalized 2D-CNW showed enhancement in both Mott-Schottky profiles and LSV properties which suggested that these hierarchical networks showed promising potential application as effective charge-trapping medium in PEC systems. Noor Hamizah Khanis, Richard Ritikos, Wee Siong Chiu, Choon Yian Haw, Nur Maisarah Abdul Rashid, Mei Yuen Chia, Poi Sim Khiew, and Saadah Abdul Rahman Copyright © 2017 Noor Hamizah Khanis et al. All rights reserved. Preparation of AuNPs/GQDs/SiO2 Composite and Its Catalytic Performance in Oxidation of Veratryl Alcohol Thu, 09 Nov 2017 06:44:46 +0000 Composites of gold nanoparticles and graphene quantum dots (AuNPs/GQDs) exhibit excellent dispersibility in aqueous solutions. Thus, it is difficult to separate them from wet reaction systems when they are used as catalysts. To resolve this issue, in this study, an AuNPs/GQDs composite was immobilized on silicon dioxide through the hydrothermal method, which involved the formation of an amide bond between the surface GQDs of the AuNPs/GQDs composite and the amino group of the silane. The as-synthesized AuNPs/GQDs/SiO2 composite was found to be suitable for use as a heterogeneous catalyst for the oxidation of veratryl alcohol in water and exhibited catalytic activity comparable to that of bare AuNPs/GQDs as well as better recyclability. Yaoyao Yang, Jiali Zhang, Fangwei Zhang, and Shouwu Guo Copyright © 2017 Yaoyao Yang et al. All rights reserved. Synthesis of Carbon Nanofibers with Maghemite via a Modified Sol-Gel Technique Thu, 09 Nov 2017 00:00:00 +0000 Carbon nanohybrid material (CNF/γ-Fe2O3) was obtained via a modified sol-gel technique consisting of two steps: functionalization of carbon nanofibers (CNF) in H2SO4/HNO3 followed by synthesis using Fe(NO3)39H2O. As a result, the iron content of the CNF/γ-Fe2O3 was increased by more than twice from about 40% to about 87% mass percent, compared to the pristine CNF and oxidized CNF specimens, as proved by energy dispersive X-ray fluorescence. Scanning electron microscopy images exhibited “cumulus” on the CNF/γ-Fe2O3 specimen surface, which showed the highest iron mass percentage, proved by energy dispersive X-ray spectroscopy. Transmission electron microscopy images confirmed attachment of γ-Fe2O3 cumulus to the inner and outer surfaces of the CNF walls after synthesis. The characteristic peaks of Fe 2p3/2 and Fe 2p1/2 appeared in the XPS spectra obtained on CNF/γ-Fe2O3. In addition, X-ray diffraction (XRD) results indicated formation of γ-Fe2O3 during the synthesis process. The Raman spectrum of the CNF/γ-Fe2O3 sample displays peaks with positions close to characteristic peaks of highly crystalline and monodisperse maghemite nanocrystallites. The synthesis of CNF/γ-Fe2O3 leads to an increase in the hydrophilicity of CNF and magnetic properties at room temperature. Nicolás Díaz Silva, Benjamín Valdez Salas, Nicola Nedev, Mario Curiel Alvarez, José M. Bastidas Rull, Roumen Zlatev, and Margarita Stoytcheva Copyright © 2017 Nicolás Díaz Silva et al. All rights reserved. Preparation and Characterization of Pd Modified TiO2 Nanofiber Catalyst for Carbon–Carbon Coupling Heck Reaction Thu, 09 Nov 2017 00:00:00 +0000 TiO2 fibers were prepared through electrospinning of poly methyl methacrylate (PMMA) and titanium isopropoxide (TIP) solution followed by calcination of fibers in air at 500°C. Cetyltrimethylammonium bromide (CTAB) protected palladium nanoparticles (Pd NPs) prepared through reduction method were successfully adsorbed on the TiO2 nanofibers (NF). Combined studies of X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM) indicated that the synthesized Pd/TiO2 had anatase. BET indicated that the synthesized TiO2 and Pd/TiO2 had a surface area of 53.4 and 43.4 m2/g, respectively. The activity and selectivity of 1 mol% Pd/TiO2 in the Heck reaction have been investigated towards the Mizoroki-Heck carbon–carbon cross-coupling of bromobenzene (ArBr) and styrene. Temperature, time, solvent, and base were optimized and catalyst was recycled thrice. 1H NMR and 13C NMR indicated that stilbene, a known compound from literature, was obtained in various Heck reactions at temperatures between 100°C and 140°C but the recyclability was limited due to some palladium leaching and catalyst poisoning which probably arose from some residual carbon from the polymer. The catalyst was found to be highly active under air atmosphere with reaction temperatures up to 140°C. Optimized reaction condition resulted in 89.7% conversions with a TON of 1993.4 and TOF value of 332.2 hr−1. Leah O. Nyangasi, Dickson M. Andala, Charles O. Onindo, Jane C. Ngila, Banothile C. E. Makhubela, and Eric M. Ngigi Copyright © 2017 Leah O. Nyangasi et al. All rights reserved. Optical Design of Porous ZnO/TiO2 Films for Highly Transparent Glasses with Broadband Ultraviolet Protection Wed, 08 Nov 2017 07:34:34 +0000 We present a design of a bilayer porous film structure on a glass substrate for the highly efficient ultraviolet (UV) protection with high visible-light transparency. To effectively block UVB (280–315 nm) and UVA (315–400 nm), titanium dioxide (TiO2) and zinc oxide (ZnO) are used as absorbing layers having the appropriate coverages in different UV ranges with extinction coefficients, respectively. We show the process of refractive index (RI) matching by controlling porosity (). Effective RIs of porous media with TiO2 and ZnO were calculated based on volume averaging theory. Transmittances of the designed films with different effective RIs were calculated using rigorous coupled-wave analysis method. Using admittance loci method, the film thickness was optimized in center wavelengths from 450 to 550 nm. The results show that the optimal design provides high UV shielding performance at both UVA and UVB with high transparency in the visible range. We also analyze electrical field distributions in each layer and angle dependency with 3D HSV color map. Han Sung Song, Young Jin Yoo, Gil Ju Lee, Ki Soo Chang, and Young Min Song Copyright © 2017 Han Sung Song et al. All rights reserved. Effects of the Growth Time and the Thickness of the Buffer Layer on the Quality of the Carbon Nanotubes Tue, 07 Nov 2017 06:54:38 +0000 Direct growth of carbon nanotubes (CNTs) array onto silicon substrate by the chemical vapor deposition (CVD) is reported. Experimental results show that the thickness of the buffer layer has a significant effect on the morphology and defects of the array, and when the buffer layer is about 15 nm, the best array on the silicon substrate can be obtained. Moreover, when the growth time is less than the threshold time (70 minutes), the array height will increase with the increase of the time. Importantly, when the growth time is higher than this threshold time, the growth of array will stop, but when the growth is continuing, the amorphous carbon and carbon can cluster, which will affect the structure of the array. These results provide a good material basis for the device, thermal, and conductivity technology. J. Chuen Copyright © 2017 J. Chuen. All rights reserved. Tuning the Photoluminescence of Graphene Quantum Dots by Fluorination Tue, 07 Nov 2017 00:00:00 +0000 Fluorinated graphene quantum dots (F-GQDs) were prepared by mixing GQDs and XeF2 in a facile gaseous phase heating method. The F-GQDs with excellent water solubility have a F/C atomic ratio of 84.25% and a diameter of 2–6 nm. The photoluminescence (PL) properties of GQDs and F-GQDs were investigated systematically. The results showed that the PL emission of the F-GQDs exhibited an obvious blue-shift of 90 nm compared to that of the GQDs. Yi Luo, Yongjie Xu, Ming Li, Lang Sun, Guanghui Hu, Tao Tang, Jianfeng Wen, and Xinyu Li Copyright © 2017 Yi Luo et al. All rights reserved. Dose-Dependent Antimicrobial Activity of Silver Nanoparticles on Polycaprolactone Fibers against Gram-Positive and Gram-Negative Bacteria Mon, 06 Nov 2017 06:17:08 +0000 The adhesion ability and adaptability of bacteria, coupled with constant use of the same bactericides, have made the increase in the diversity of treatments against infections necessary. Nanotechnology has played an important role in the search for new ways to prevent and treat infections, including the use of metallic nanoparticles with antibacterial properties. In this study, we worked on the design of a composite of silver nanoparticles (AgNPS) embedded in poly-epsilon-caprolactone nanofibers and evaluated its antimicrobial properties against various Gram-positive and Gram-negative microorganisms associated with drug-resistant infections. Polycaprolactone-silver composites (PCL-AgNPs) were prepared in two steps. The first step consisted in the reduction in situ of Ag+ ions using N,N-dimethylformamide (DMF) in tetrahydrofuran (THF) solution, and the second step involved the simple addition of polycaprolactone before electrospinning process. Antibacterial activity of PCL-AgNPs nanofibers against E. coli, S. mutans, K. pneumoniae, S. aureus, P. aeruginosa, and B. subtilis was evaluated. Results showed sensibility of E. coli, K. pneumoniae, S. aureus, and P. aeruginosa, but not for B. subtilis and S. mutans. This antimicrobial activity of PCL-AgNPs showed significant positive correlations associated with the dose-dependent effect. The antibacterial property of the PCL/Ag nanofibers might have high potential medical applications in drug-resistant infections. Erick Pazos-Ortiz, Jose Hafid Roque-Ruiz, Efrén Amador Hinojos-Márquez, Juan López-Esparza, Alejandro Donohué-Cornejo, Juan Carlos Cuevas-González, León Francisco Espinosa-Cristóbal, and Simón Yobanny Reyes-López Copyright © 2017 Erick Pazos-Ortiz et al. All rights reserved. Study of the Optical Properties of Functionalized Gold Nanoparticles in Different Tissues and Their Correlation with the Temperature Increase Mon, 06 Nov 2017 00:00:00 +0000 Mie theory explains the interaction of light with a gold nanoparticle (AuNP) through the absorption , scattering , and extinction cross sections. These parameters have been calculated in the case of AuNPs dispersed in homogeneous media, but not for specific tissues. The aim of this research was to theoretically obtain the optical cross sections (,, and ) of functionalized AuNPs in liver and colon tissues through Mie theory and correlate them with the temperature increase observed experimentally in tissues containing AuNPs under plasmonic photothermal irradiation using a Nd-YAG laser (λ = 532 nm). Calculations showed that represents % of at 532 nm. The value for a functionalized AuNP in water was 365.66 nm2 (94% of the theoretical maximum value at 522.5 nm), 404.24 nm2 in colon (98% of the theoretical maximum value at 525 nm), and 442.39 nm2 in liver (96% of the theoretical maximum value at 525 nm). Therefore, nanoparticles irradiated at 532 nm are very close to their resonance value. These results correlated with the experimental irradiation of functionalized AuNPs in different tissues, where the average temperature increase showed the pattern liver > colon > water. The temperature increase observed ( up to 13°C) is sufficient to produce cellular death. A. Carrillo-Cazares, N. P. Jiménez-Mancilla, M. A. Luna-Gutiérrez, K. Isaac-Olivé, and M. A. Camacho-López Copyright © 2017 A. Carrillo-Cazares et al. All rights reserved. Metasurfaces-Based Absorption and Reflection Control: Perfect Absorbers and Reflectors Mon, 06 Nov 2017 00:00:00 +0000 In the past decade, the realisation of negative index materials has initiated extensive research into metamaterials. Perfect absorbers and reflectors are of particular interest as their usefulness is endless in a range of different fields and devices. Since it was originally shown that a device can achieve unity absorption of electromagnetic waves, it has become a hot area of research to develop perfect absorbers based on polarisation independence and incident angle independence, at a range of frequencies from microwave to optical ones. The amazing performance, flexibility, and tunability of these metamaterials will be discussed here, by presenting the different designs and working mechanisms that have been realised up to now. Their limitations and shortcomings will be addressed and future plans for perfect absorbers and reflectors will be suggested. Trevon Badloe, Jungho Mun, and Junsuk Rho Copyright © 2017 Trevon Badloe et al. All rights reserved. Carbon-Based Nanomaterials as Novel Nanosensors Sun, 05 Nov 2017 00:00:00 +0000 Qin Hu, Evan K. Wujcik, Antonios Kelarakis, Jobin Cyriac, and Xiaojuan Gong Copyright © 2017 Qin Hu et al. All rights reserved. Inkjet-Printed CdTe Quantum Dots-Polyurethane Acrylate Thin Films Thu, 02 Nov 2017 00:00:00 +0000 We demonstrated the inkjet-printed CdTe quantum dots-polyurethane acrylate thin films and their potential application in the display devices. The water soluble CdTe QDs were synthesized through the wet chemistry and the emission wavelengths can be freely tuned during the preparation process. Combining with the UV curable resin polyurethane acrylate, the QDs inks were prepared and the influence of diluent and water content on the performance of resultant films was studied. The tensile stress of the films cured from the QDs inks with diluent increased from 10.6 MPa to 27.5 MPa and the low water content led to uniform polymer matrix. Furthermore, the existence of diluent and low water content would all improve the fluorescence stability of the thin films. Finally, the thin films can be deposited on different substrates and well controlled to meet the RGB color standard, which will pave the way to a simple, low-cost, large-scale, and highly reliable method for the application of flexible displays. Lei Du, Zhejun Liu, and Suhua Jiang Copyright © 2017 Lei Du et al. All rights reserved. Folate-Functionalized Mesoporous Silica Nanoparticles as a Liver Tumor-Targeted Drug Delivery System to Improve the Antitumor Effect of Paclitaxel Tue, 31 Oct 2017 00:00:00 +0000 The aim of this study was to prepare and characterize an innovative hepatocellular carcinoma-targeted therapeutic drug delivery system based on folate-PEG-mesoporous silica nanoparticles (FA-PEG-MSNs) loaded with paclitaxel (PTX). In vitro cell experiments and an in vivo antitumor efficacy study demonstrated that FA-PEG-MSNs-PTX produced significantly higher tumor inhibition compared with pure PTX and mesoporous silica nanoparticles loaded with paclitaxel (MSNs-PTX). The biodistribution investigation of PTX in nude mice revealed that the FA-PEG-MSNs-PTX could accumulate in tumors. Folic acid functionalized MSNs resulted in a good targeting effect, confirming that FA-PEG-MSNs-PTX is a promising tumor-targeted drug delivery system for liver cancer chemotherapy. Xiaoyan Xu, Chao Wu, Andi Bai, Xuan Liu, Huiling Lv, and Ying Liu Copyright © 2017 Xiaoyan Xu et al. All rights reserved. Effect of Filler Shape on the Thermal Conductivity of Thermal Functional Composites Mon, 30 Oct 2017 09:04:58 +0000 With the rapid development of electronic industry, heat dissipation issue becomes more and more important. Thermal functional composites (TFCs) are usually binary composites, filled with thermal conductive additives (nanomaterials) in matrix, and the composites show good thermal performance. The theoretical and experimental results show that the filler shape is one of the most important but easily overlooked factors. In this article, we provide a systematic review of the effect of the filler shape on the thermal conductivity of TFCs, and the heat transfer enhancement based on synergistic effect is also summed up. Finally, the future trends of further improving thermal properties of TFCs are predicted. Changqing Liu, Mao Chen, Dongyi Zhou, Dezhi Wu, and Wei Yu Copyright © 2017 Changqing Liu et al. All rights reserved. Heat Treatment Effect on Eu3+ Doped TeO2-BaO-Bi2O3 Glass Systems with Ag Nanoparticles Mon, 30 Oct 2017 06:15:22 +0000 Glass systems of 73TeO2-4BaO-3Bi2O3-2Eu2O3-xAg (in molar ratio where x = 0, 1, 2, and 3) compositions have been successfully synthesized. Silver nanoparticles were obtained with the employment of heat treatment (HT) procedure executed at 350°C. Glass transition temperatures of different compositions have been determined through DSC measurements. XRD results presented characteristic amorphous halo indicating lack of long range order in the samples. FTIR structural studies revealed that glass matrix is mainly composed of TeO3 and TeO4 species and is stable after different applied heat treatment times. X-ray photoelectron spectroscopy (XPS) measurements confirmed that in selected samples part of Ag ions changed oxidation state to form Ag0 species. TEM measurements revealed nanoparticles of size in the range of 20–40 nm. UV-vis absorption results demonstrated characteristic transitions of Eu3+ ions. Additionally, UV-vis spectra of samples heat-treated for 6, 12, 24, and 48 hours presented bands related to silver nanoparticles. Photoluminescence (PL) studies have been performed with excitation wavelength of  nm. Obtained spectra exhibited peaks due to 5D0-7FJ (where ) and 5D1-7FJ (where ) transitions of Eu3+. Moreover, luminescence measurement indicated enhancement of rare earth ions emissions in several of the annealed samples. Increase of emission intensity of about 35% has been observed. Tomasz Lewandowski, Michał Dembski, Michalina Walas, Marcin Łapiński, Magdalena Narajczyk, Wojciech Sadowski, and Barbara Kościelska Copyright © 2017 Tomasz Lewandowski et al. All rights reserved. Low-Dimensional Nanomaterials and Their Functional Architectures: Synthesis, Properties, and Applications Thu, 26 Oct 2017 09:50:54 +0000 Weilu Gao, Ciyuan Qiu, and Xiaowei He Copyright © 2017 Weilu Gao et al. All rights reserved. Characterization and Analytical Separation of Fluorescent Carbon Nanodots Thu, 26 Oct 2017 00:00:00 +0000 Carbon nanodots (C-dots) are recently discovered fluorescent carbon nanoparticles with typical sizes of <10 nm. The C-dots have been reported to have excellent photophysical and chemical characteristics. In recent years, the advances in the development and improvement in C-dots synthesis, characterization, and applications are burgeoning. In this review, we introduce the most commonly used techniques for the characterization of C-dots. The characterization techniques for C-dots are briefly classified, described, and illustrated with applied examples. In addition, the analytical separation methods for C-dots (including electrophoresis, chromatography, density gradient centrifugation, differential centrifugation, solvent extraction, and dialysis) are included and discussed according to their analytical characteristics. The review concludes with an outlook towards the future developments in the characterization and the analytical separation of C-dots. The comprehensive overview of the characterization and the analytical separation techniques will safeguard people to use each technique more wisely. Qin Hu, Xiaojuan Gong, Lizhen Liu, and Martin M. F. Choi Copyright © 2017 Qin Hu et al. All rights reserved. Synthesis, Properties, and Applications of Multifunctional Magnetic Nanostructures Wed, 25 Oct 2017 09:57:46 +0000 Vidyadhar Singh, Rajasekhar Madugundo, Anil Annadi, Biswanath Bhoi, K. Devi Chandrasekhar, and Murtaza Bohra Copyright © 2017 Vidyadhar Singh et al. All rights reserved. Studies of the Influence of Gold Nanoparticles on Characteristics of Mesenchymal Stem Cells Tue, 24 Oct 2017 00:00:00 +0000 The aim of the present study is to determine what effect the different concentrations of 15 nm gold nanoparticles (AuNPs) will have on the immunophenotype, synthesis collagen type I, ability to direct differentiation and spectroscopic characteristics of bone marrow mesenchymal stem cells (MSCs). The AuNPs in concentrations of 1.5–9 μg/ml did not lead to changes in the level of expression of CD 45, CD 90, and CD 73. It should be noted that AuNPs in concentrations of 6 and 9 μg/ml led to a decrease in CD 44 cells by 6% and 9%, respectively. The content of CD 105 cells was reduced by 5% when AuNPs were applied at a concentration of 9 μg/ml. It was found that AuNPs in concentrations of 1.5–6 μg/ml are safe for MSCs, while the increase up to 9 μg/ml has a toxic effect, manifested by the reduction of synthesis collagen type I and ability of adipogenic differentiation. IR spectroscopy data have shown that the AuNPs at concentrations of 9 μg/ml under conditions of adipogenic differentiation to MSCs lead to the destruction processes in the cells. The obtained results are related to the field of applied nanotechnology, which extends to regenerative medicine, especially in development of bioimplantology. Nataliia Volkova, Olena Pavlovich, Olena Fesenko, Oksana Budnyk, Serhii Kovalchuk, and Anatoliy Goltsev Copyright © 2017 Nataliia Volkova et al. All rights reserved. Quantum-Dot and Polychalcone Mixed Nanocomposites for Polymer Light-Emitting Diodes Mon, 23 Oct 2017 08:24:16 +0000 The present work is aimed at improving the efficiency of light-emitting diodes (LEDs) through the amalgamation of polymeric materials and quantum dots (QDs) in nanocomposites. Herein, we report on the polytriphenylamine-based chalcone (PTpC) or polycarbazole-based chalcone- (PCzC-) QDs mixture nanocomposites as emissive layers for polymer LEDs (PLEDs). QDs were evenly dispersed in the polymer matrix and the synthesized PTpC-QDs and PCzC-QDs nanocomposites were able to form smooth thin films. The luminance characteristics of PTpC-QDs and PCzC-QDs nanocomposites were better than those of the pristine QD, PTpC, and PCzC materials, owing to the high charge-carrier transport ability of polymer-QDs nanocomposites. These results indicate that the proposed polymer-QDs nanocomposites could be potential candidates for application in PLEDs. Vanaraj Ramkumar and Sanghyun Ju Copyright © 2017 Vanaraj Ramkumar and Sanghyun Ju. All rights reserved. Mechanical Properties of Epoxy and Its Carbon Fiber Composites Modified by Nanoparticles Thu, 19 Oct 2017 00:00:00 +0000 Compressive properties are commonly weak parts in structural application of fiber composites. Matrix modification may provide an effective way to improve compressive performance of the composites. In this work, the compressive property of epoxies (usually as matrices of fiber composites) modified by different types of nanoparticles was firstly investigated for the following study on the compressive property of carbon fiber reinforced epoxy composites. Carbon fiber/epoxy composites were fabricated by vacuum assisted resin infusion molding (VARIM) technique using stitched unidirectional carbon fabrics, with the matrices modified with nanosilica, halloysite, and liquid rubber. Testing results showed that the effect of different particle contents on the compressive property of fiber/epoxy composites was more obvious than that in epoxies. Both the compressive and flexural results showed that rigid nanoparticles (nanosilica and halloysite) have evident strengthening effects on the compression and flexural responses of the carbon fiber composite laminates fabricated from fabrics. Fang Liu, Shiqiang Deng, and Jianing Zhang Copyright © 2017 Fang Liu et al. All rights reserved. Rapid Detection and Identification of miRNAs by Surface-Enhanced Raman Spectroscopy Using Hollow Au Nanoflowers Substrates Thu, 19 Oct 2017 00:00:00 +0000 MicroRNAs (miRNAs) are recognized as regulators of gene expression during the biological processes of cells as well as biomarkers of many diseases. Development of rapid and sensitive miRNA profiling methods is crucial for evaluating the pattern of miRNA expression related to normal and diseased states. This work presents a novel hollow Au nanoflowers (HAuNFs) substrate for rapid detection and identification of miRNAs by surface-enhanced Raman scattering (SERS) spectroscopy. We synthesized the HAuNFs by a seed-mediated growth approach. Then, HAuNFs substrates were fabricated by depositing HAuNFs onto the surfaces of (3-aminopropyl)triethoxysilane- (APTES-) functionalized ITO glass. The result demonstrated that HAuNFs substrates had very good reproducibility, homogeneous SERS activity, and high SERS effect. The substrates enabled us to successfully obtain the SERS spectra of miR-10a-5p, miR-125a-5p, and miR-196a-5p. The difference spectra among the three kinds of miRNAs were studied to better interpret the spectral differences and identify miRNA expression patterns with high accuracy. The principal component analysis (PCA) of the SERS spectra was used to distinguish among the three kinds of miRNAs. Considering its time efficiency, being label-free, and its sensitivity, the SERS based on HAuNFs substrates is very promising for miRNA research and plays an important role in early disease detection and prevention. Xiaowei Cao, Min Bao, Yibo Shan, Wei Li, and Hongcan Shi Copyright © 2017 Xiaowei Cao et al. All rights reserved. Fabrication of a Large-Area Superhydrophobic SiO2 Nanorod Structured Surface Using Glancing Angle Deposition Mon, 16 Oct 2017 00:00:00 +0000 A glancing angle deposition (GLAD) technique was used to generate SiO2 nanorods on a glass substrate to fabricate a low-cost superhydrophobic functional nanostructured surface. GLAD-deposited SiO2 nanorod structures were fabricated using various deposition rates, substrate rotating speeds, oblique angles, and deposition times to analyze the effects of processing conditions on the characteristics of the fabricated functional nanostructures. The wettability of the surface was measured after surface modification with a self-assembled monolayer (SAM). The measured water contact angles were primarily affected by substrate rotation speed and oblique angle because the surface fraction of the GLAD nanostructure was mainly affected by these parameters. A maximum contact angle of 157° was obtained from the GLAD sample fabricated at a rotation speed of 5 rpm and an oblique angle of 87°. Although the deposition thickness (height of the nanorods) was not a dominant factor for determining the wettability, we selected a deposition thickness of 260 nm as the optimum processing condition based on the measured optical transmittance of the samples because optically transparent films can serve as superhydrophobic functional nanostructures for optical applications. Xun Lu, Seok-min Kim, and Seong Jun Seo Copyright © 2017 Xun Lu et al. All rights reserved. Enhanced Piezoelectric Behavior of PVDF Nanocomposite by AC Dielectrophoresis Alignment of ZnO Nanowires Sun, 15 Oct 2017 00:00:00 +0000 In contrast to commercial piezoelectric ceramics, lead-free materials such as ZnO and a polymer matrix are proper candidates for use in ecofriendly applications. In this article, the authors represent a technique using ZnO nanowires with a polyvinylidene fluoride (PVDF) matrix in a piezoelectric polymer composite. By aligning the nanowires in the matrix in a desired direction by AC dielectrophoresis, the piezoelectric behavior was enhanced. The dielectric constant of the composite was improved by increasing the concentration of the ZnO nanowires as well. Specifically, the resulting dielectric constant shows an improvement of 400% with aligned ZnO nanowires by increasing the poling effect compared to that of a randomly oriented nanowire composite without a poling process. Kyungwho Choi, Woongchul Choi, Choongho Yu, and Yong Tae Park Copyright © 2017 Kyungwho Choi et al. All rights reserved. Enhancement of Fluorescence and Photostability Based on Interaction of Fluorescent Dyes with Silver Nanoparticles for Luminescent Solar Concentrators Sun, 15 Oct 2017 00:00:00 +0000 For luminescent solar concentrators (LSCs), it is important to enhance the fluorescence quantum yield (FQY) and photostability. Our measurements have demonstrated that the addition of silver nanoparticles to dye solution causes broadening of absorption bands, so the spectral range of sunlight absorbed by LSC has increased. Silver nanoparticles (NPs) were characterized by X-ray diffraction (XRD) and UV-Vis absorption spectra. UV-Vis spectrum showed a single peak at 442 nm due to the surface plasmon resonance (SPR). The position of SPR peak exhibited a red shift after the sample was exposed to UV irradiation (unfiltered light). The optical band gap values have a reduction from 2.46 to 2.37 eV after irradiation for 960 minutes. Such reduction in optical band gap may be due to change in particle size calculated using Mie theory. The photostability of organic dyes used was improved after adding silver nanoparticles. The area under fluorescence spectra of dyes with silver NPs increased by 41–31% when compared with identical dye concentrations without silver nanoparticles as a result of interaction of the species with silver NPs. Sara El-Molla, A. F. Mansour, and A. E. Hammad Copyright © 2017 Sara El-Molla et al. All rights reserved. Effects of Nanosilica on Early Age Stages of Cement Hydration Thu, 12 Oct 2017 08:52:08 +0000 Effects of nanosilica on cement hydration have been broadly investigated in the literature and early age cement hydration, as a whole, has been mainly considered, disregarding the substages of the hydration. The hydration of cement is characterized by different substages and nanosilica effect on the hydration could be a result of diverse, even contradictory, behavior of nanosilica in individual stages of the hydration. In this study, effects of nanosilica on different substages of cement hydration are investigated. Isothermal calorimetry results show that at early ages (initial 72 hours) the effects of nanosilica depend on the phenomenon by which the hydration is governed: when the hydration is chemically controlled, that is, during initial reaction, dormant period, and acceleratory period, the hydration rate is accelerated by adding nanosilica; when the hydration is governed by diffusion process, that is, during postacceleratory period, the hydration rate is decelerated by adding nanosilica. The Thermal Gravimetric Analysis on the samples at the hardened state (after 28 days of curing) reveals that, after adding nanosilica, the hydration degree slightly increased compared to the plain paste. Forood Torabian Isfahani, Elena Redaelli, Weiwen Li, and Yaru Sun Copyright © 2017 Forood Torabian Isfahani et al. All rights reserved.