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metal nanoparticle

Bruno Fabre, Gaozeng Li, Francis Gouttefangeas, Loic Joanny, Gabriel Loget
The electroless deposition of Pt nanoparticles (NPs) on hydrogen-terminated silicon (H-Si) surfaces is studied as a function of temperature and the immersion time. It is demonstrated that isolated Pt structures can be produced at all investigated temperatures (between 22 and 75°C) for short deposition times, typically within 1-10 min if the temperature was 45°C or less than 5 min at 75°C. For longer times, dendritic metal structures start to grow leading ultimately to highly rough interconnected Pt networks...
October 25, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
M Zubair Akbar Qureshi, Qammar Rubbab, Saadia Irshad, Salman Ahmad, M Aqeel
Energy generation is currently a serious concern in the progress of human civilization. In this regard, solar energy is considered as a significant source of renewable energy. The purpose of the study is to establish a thermal energy model in the presence of spherical Au-metallic nanoparticles. It is numerical work which studies unsteady magnetohydrodynamic (MHD) nanofluid flow through porous disks with heat and mass transfer aspects. Shaped factor of nanoparticles is investigated using small values of the permeable Reynolds number...
December 2016: Nanoscale Research Letters
Chrystelle Neaime, Maria Amela-Cortes, Fabien Grasset, Yann Molard, Stéphane Cordier, Benjamin Dierre, Michel Mortier, Toshiaki Takei, Kohsei Takahashi, Hajime Haneda, Marc Verelst, Séverine Lechevallier
Bioimaging and cell labeling using red or near infrared phosphors emitting in the "therapeutic window" of biological tissues have recently become some of the most active research fields in modern medical diagnostics. However, because organic and inorganic autofluorophores are omnipresent in nature, very often the background signal from fluorochromes other than targeted probes has to be eliminated. This discrimination could be available using a time-gated luminescence microscopy (TGLM) technique associated with long lifetime phosphorescent nanocomposites...
October 25, 2016: Physical Chemistry Chemical Physics: PCCP
Marco Aurélio Versiani, Fuad Jacob Abi Rached-Junior, Anil Kishen, Jesus Djalma Pécora, Yara Terezinha Silva-Sousa, Manoel Damião de Sousa-Neto
INTRODUCTION: Metallic antibacterial nanoparticles have been shown to provide distinct antibacterial advantage and antibiofilm efficacy when applied in infected root canals. The purpose of this study was to evaluate the influence of incorporating zinc oxide nanoparticles (ZnO-Np) on the physicochemical properties of Grossman sealer. METHODS: Grossman sealer was prepared according to its original formula. Additionally, 4 experimental sealers were prepared by replacing the zinc oxide component of the powder with ZnO-Np (average size of 20 nm) in different amounts (25%, 50%, 75%, and 100%)...
October 21, 2016: Journal of Endodontics
Slavica Stankic, Sneha Suman, Francia Haque, Jasmina Vidic
Th antibacterial activity of metal oxide nanoparticles has received marked global attention as they can be specifically synthesized to exhibit significant toxicity to bacteria. The importance of their application as antibacterial agents is evident keeping in mind the limited range and effectiveness of antibiotics, on one hand, and the plethora of metal oxides, on the other, along with the propensity of nanoparticles to induce resistance being much lower than that of antibiotics. Effective inhibition against a wide range of bacteria is well known for several nano oxides consisting of one metal (Fe3O4, TiO2, CuO, ZnO), whereas, research in the field of multi-metal oxides still demands extensive exploration...
October 24, 2016: Journal of Nanobiotechnology
Melanie Wright, Joshua Adams, Kwang Yang, Paul McManus, Astrid Jacobson, Aniket Gade, Joan McLean, David Britt, Anne Anderson
Nanoparticle (NPs) containing essential metals are being considered in formulations of fertilizers to boost plant nutrition in soils with low metal bioavailability. This paper addresses whether colonization of wheat roots by the bacterium, Pseudomonas chlororaphis O6 (PcO6), protected roots from the reduced elongation caused by CuO NPs. There was a trend for slightly elongated roots when seedlings with roots colonized by PcO6 were grown with CuO NPs; the density of bacterial cells on the root surface was not altered by the NPs...
2016: PloS One
Quentin Jeangros, Martial Duchamp, Jérémie Werner, Maximilian Kruth, Rafal E Dunin-Borkowski, Björn Niesen, Christophe Ballif, Aïcha Hessler-Wyser
Changes in the nanostructure of methylammonium lead iodide (MAPbI3) perovskite solar cells are assessed as a function of current/voltage stimulus by biasing thin samples in situ in a transmission electron microscope. Various degradation pathways are identified both in situ and ex situ, predominantly at the positively biased MAPbI3 interface. Iodide migrates into the positively biased transport layer and also volatilises along with organic species, which triggers the nucleation of PbI2 nanoparticles and voids and hence decreases the cell performance...
October 24, 2016: Nano Letters
Tae Soup Shim, Zaki G Estephan, Zhaoxia Qian, Jacob H Prosser, Su Yeon Lee, David M Chenoweth, Daeyeon Lee, So-Jung Park, John C Crocker
Active materials that respond to physical and chemical stimuli can be used to build dynamic micromachines that lie at the interface between biological systems and engineered devices. In principle, the specific hybridization of DNA can be used to form a library of independent, chemically driven actuators for use in such microrobotic applications and could lead to device capabilities that are not possible with polymer- or metal-layer-based approaches. Here, we report shape changing films that are powered by DNA strand exchange reactions with two different domains that can respond to distinct chemical signals...
October 24, 2016: Nature Nanotechnology
Ayman M Atta, Hamad A Al-Lohedan, Ahmed M Tawfik, Abdelrahman O Ezzat
This work first reports the preparation of super-amphiphilic silica-nanogel composites to reduce the contact angle of water to increase the diffusion of pollutant into adsorbents. In this respect, the silica nanoparticles were encapsulated into nanogels based on ionic and nonionic polyacrylamides by dispersion polymerization technique. The morphologies and the dispersion stability of nanogel composites were investigated to clarify the ability of silica-nanogel composites to adsorb at different interfaces. The feasibility of silica polyacrylamide nanogel composites to act as a high-performance adsorbent for removal of methylene blue (MB) dye and heavy metals (Co(2+) and Ni(2+)) from aqueous solution was investigated...
October 19, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Safaa Al-Rehili, Karim Fhayli, Mohamed Amen Hammami, Basem Moosa, Sachin Patil, Daliang Zhang, Ohoud Alharbi, Mohamed Nejib Hedhili, Helmuth Möhwald, Niveen M Khashab
Toroidal structures based on self-assembly of predesigned building blocks are well established in literature however, spontaneous self-organization to prepare such structures has never been reported thus far. Here, organic-inorganic hybrid microtoroids synthesized by simultaneous coordination-driven assembly of amphiphilic molecules and hydrophilic polymers are reported. Mixing amphiphilic molecules with iron(III) chloride and hydrophilic polymers in water leads, within minutes, to the formation of star-like nanostructures...
October 24, 2016: Journal of the American Chemical Society
Xiaolei Zhang, Huimin Sui, Xiaolei Wang, Hongyang Su, Weina Cheng, Xu Wang, Bing Zhao
A nanoscale metal-molecule-semiconductor assembly (Ag/4-mercaptophenol/TiO2) has been fabricated over Au nanoparticle (NP) films as a model to study the interfacial charge transfer (CT) effects involved in Ag/MPH/TiO2. Due to the interaction between Au NPs and Ag NPs, some distinct differences occur in the SERS spectra. We also measured the SERS of Ag/MPH (4-mercaptophenol), Ag/MPH/TiO2, and Au/Ag/MPH/TiO2 assemblies at excitation wavelengths of 477, 514, 532, 633, and 785 nm. We found that the changes in the CT process, caused by the introduction of TiO2 and Au, can be reflected in SERS...
October 24, 2016: Physical Chemistry Chemical Physics: PCCP
Meng Zhou, Chenjie Zeng, Yuxiang Chen, Shuo Zhao, Matthew Y Sfeir, Manzhou Zhu, Rongchao Jin
The evolution from the metallic (or plasmonic) to molecular state in metal nanoparticles constitutes a central question in nanoscience research because of its importance in revealing the origin of metallic bonding and offering fundamental insights into the birth of surface plasmon resonance. Previous research has not been able to probe the transition due to the unavailability of atomically precise nanoparticles in the 1-3 nm size regime. Herein, we investigate the transition by performing ultrafast spectroscopic studies on atomically precise thiolate-protected Au25, Au38, Au144, Au333, Au∼520 and Au∼940 nanoparticles...
October 24, 2016: Nature Communications
Keumnam Cho, Sung-Hwan Han, Myunghyun Paik Suh
To apply electrically nonconductive metal-organic frameworks (MOFs) in an electrocatalytic oxygen reduction reaction (ORR), we have developed a new method for fabricating various amounts of CuS nanoparticles (nano-CuS) in/on a 3D Cu-MOF, [Cu3 (BTC)2 ⋅(H2 O)3 ] (BTC=1,3,5-benzenetricarboxylate). As the amount of nano-CuS increases in the composite, the electrical conductivity increases exponentially by up to circa 10(9) -fold, while porosity decreases, compared with that of the pristine Cu-MOF. The composites, nano-CuS(x wt %)@Cu-BTC, exhibit significantly higher electrocatalytic ORR activities than Cu-BTC or nano-CuS in an alkaline solution...
October 24, 2016: Angewandte Chemie
Arvin Eskandari, Janine N Boodram, Paul B Cressey, Chunxin Lu, Peter M Bruno, Michael T Hemann, Kogularamanan Suntharalingam
We report the cancer stem cell (CSC) potency of a novel series of copper(ii)-phenanthroline complexes bearing nonsteriodial anti-inflammatory drugs: naproxen, tolfenamic acid, and indomethacin (2a-3c). Two of the complexes, 2a and 3c, kill breast CSC-enriched HMLER-shEcad cells (grown in both monolayer and three-dimensional cell cultures) to a significantly better extent than salinomycin, a well-established CSC toxin. The most potent complex in the series, 3c induces its cytotoxic effect by generating intracellular reactive oxygen species (ROS) and inhibiting cyclooxgenase-2 (COX-2) activity...
October 24, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Liping Zhang, Ping Cui, Hongbin Yang, Jiazang Chen, Fangxing Xiao, Yuanyuan Guo, Ye Liu, Weina Zhang, Fengwei Huo, Bin Liu
Ti-based metal-organic frameworks (MOFs) are demonstrated as promising photosensitizers for photoelectrochemical (PEC) water splitting. Photocurrents of TiO2 nano wire photoelectrodes can be improved under visible light through sensitization with aminated Ti-based MOFs. As a host, other sensitizers or catalysts such as Au nanoparticles can be incorporated into the MOF layer thus further improving the PEC water splitting efficiency.
January 2016: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
G Gupta, S Sharma, P M Mendes
The current study investigated the unique combination of alloying (Pt with Cr) and Nafion stabilisation to reap the benefits of catalyst systems with enhanced catalytic activity and improved durability in PEMFCs. Pt-Cr alloy nanoparticles stabilised with Nafion were chosen in the current study owing to their higher stability in acidic and oxidising media at high temperatures compared to other Pt-transition metal alloys (e.g. Pt-Ni, Pt-Co). Two different precursor : reducing agent (1 : 10 and 1 : 20) ratios were used in order to prepare two different alloys, denoted as Pt-Cr 10 and Pt-Cr 20...
September 15, 2016: RSC Advances
Sulena Pradhan, Jonas Hedberg, Eva Blomberg, Susanna Wold, Inger Odnevall Wallinder
ABSTRACT: In this study, we elucidate the effect of different sonication techniques to efficiently prepare particle dispersions from selected non-functionalized NPs (Cu, Al, Mn, ZnO), and corresponding consequences on the particle dose, surface charge and release of metals. Probe sonication was shown to be the preferred method for dispersing non-inert, non-functionalized metal NPs (Cu, Mn, Al). However, rapid sedimentation during sonication resulted in differences between the real and the administered doses in the order of 30-80 % when sonicating in 1 and 2...
2016: Journal of Nanoparticle Research: An Interdisciplinary Forum for Nanoscale Science and Technology
Ting Liu, Jiang Xue Dong, Shi Gang Liu, Na Li, Shu Min Lin, Yu Zhu Fan, Jing Lie Lei, Hong Qun Luo, Nian Bing Li
A stable silver nanoparticles/carbon quantum dots (Ag/CQDs) composite was prepared by using CQDs as reducing and stabilizing agent. The CQDs synthesized with polyethyleneimine (PEI) showed an extraordinary reducibility. When Hg(2+) was presented in the Ag/CQDs composite solution, a color change from yellow to colorless was observed, accompanied by a shift of surface plasmon resonance (SPR) band and decrease in absorbance of the Ag/CQDs composite. On the basis of the further studies on TEM, XPS and XRD analysis, the possible mechanism is attributed to the formation of a silver-mercury amalgam...
October 17, 2016: Journal of Hazardous Materials
Cheng-Yu Shih, Chengping Wu, Maxim V Shugaev, Leonid V Zhigilei
Laser ablation in liquids is actively used for generation of clean colloidal nanoparticles with unique shapes and functionalities. The fundamental mechanisms of the laser ablation in liquids and the key processes that control the nanoparticle structure, composition, and size distribution, however, are not yet fully understood. In this paper, we report the results of first atomistic simulations of laser ablation of metal targets in liquid environment. A model combining a coarse-grained representation of the liquid environment (parameterized for water), a fully atomistic description of laser interactions with metal targets, and acoustic impedance matching boundary conditions is developed and applied for simulation of laser ablation of a thin silver film deposited on a silica substrate...
October 15, 2016: Journal of Colloid and Interface Science
Arash Asfaram, Mehrorang Ghaedi, Kheibar Dashtian
Magnetite (Fe3O4 nanoparticles (NPs)) HKUST-1 metal organic framework (MOF) composite as a support was used for surface imprinting of gallic acid imprinted polymer (HKUST-1-MOF-Fe3O4-GA-MIP) using vinyltrimethoxysilane (VTMOS) as the cross-linker. Subsequently, HKUST-1-MOF-Fe3O4-NPs-GA-MIP characterized by FT-IR, XRD and FE-SEM analysis and applied for fast and selective and sensitive ultrasound assisted dispersive magnetic solid phase microextraction of gallic acid (GA) by UV-Vis (UA-DMSPME-UV-Vis) detection method...
January 2017: Ultrasonics Sonochemistry
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