Determination of the static spring constant of electrically-driven quartz tuning forks with two freely oscillating prongs

Quartz tuning forks have become popular in nanotechnology applications, especially as sensors for scanning probe microscopy. The sensor’s spring constant and the oscillation amplitude are required parameters to evaluate the tip-sample forces; however, there is certain controversy within the research community as to how to arrive at a value for the static spring constant of the device when working in shear mode. Here, we present two different methods based on finite element simulations, to determine the value of the spring constant of the sensors: the amplitude and Cleveland methods. The results obtained using these methods are compared to those using the geometrical method, and show that the latter overestimates the spring constant of the device.

Laura Gonz?lez, Roger Oria, Luis Botaya, Manel Puig-Vidal and Jorge Otero

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Self-assembly of nanoparticles onto the surfaces of polystyrene spheres with a tunable composition and loading

Functional colloidal materials were prepared by design through the self-assembly of nanoparticles (NPs) on the surfaces of polystyrene (PS) spheres with control over NP surface coverage, NP-to-NP spacing, and NP composition. The ability to control and fine tune the coating was extended to the first demonstration of the co-assembly of NPs of dissimilar composition onto the same PS sphere, forming a multi-component coating. A broad range of NP decorated PS (PS@NPs) spheres were prepared with uniform coatings attributed to electrostatic and hydrogen bonding interactions between stabilizing groups on the NPs and the functionalized surfaces of the PS spheres. This versatile two-step method provides more fine control than methods previously demonstrated in the literature. These decorated PS spheres are of interest for a number of applications, such as catalytic reactions where the PS spheres provide a support for the dispersion, stabilization, and recovery of NP catalysts. The catalyti...

Brandy K Pilapil, Michael C P Wang, Michael T Y Paul, Amir Nazemi and Byron D Gates

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Comparative toxicity evaluation of flower-shaped and spherical gold nanoparticles on human endothelial cells

In this paper, we propose a multi-parametric in vitro study of the cytotoxicity of gold nanoparticles (GNPs) on human endothelial cell (HUVEC). The cytotoxicity is evaluated by incubating cells with six different GNP types which have two different morphologies: spherical and flower-shaped, two sizes (∼15 and ∼50 nm diameter) and two surface chemistries (as prepared form and PEGylated form). Our results showed that by increasing the concentration of GNPs the cell viability decreases with a toxic concentration threshold of 10 pM for spherical GNPs and of 1 pM for flower-shaped GNPs. Dark field images, flow cytometry and spreading test revealed that flower-shaped GNPs have more deleterious effects on the cell mechanisms than spherical GNPs. We demonstrated that the main parameter in the evaluation of the GNPs toxicity is the GNPs roughness and that this effect is independent on the surface chemistry. We assume that this behavior is highly related to the efficiency of the GNPs...

Sadequa Sultana, Nadia Djaker, Sanda Boca-Farcau, Milena Salerno, Nathalie Charnaux, Simion Astilean, Hanna Hlawaty and Marc Lamy de la Chapelle

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Thermal conduction in single-layer black phosphorus: highly anisotropic?

The single-layer black phosphorus is characteristic for its puckered structure, which has led to distinct anisotropy in its optical, electronic, and mechanical properties. We use the non-equilibrium Greenʼs function approach and the first-principles method to investigate the thermal conductance for single-layer black phosphorus in the ballistic transport regime, in which the phonon–phonon scattering is neglected. We find that the anisotropy in the thermal conduction is very weak for the single-layer black phosphorus—the difference between two in-plane directions is less than 4%. Our phonon calculations disclose that the out-of-plane acoustic phonon branch has lower group velocities in the direction perpendicular to the pucker, as the black phosphorus is softer in this direction, leading to a weakening effect for the thermal conductance in the perpendicular direction. However, the longitudinal acoustic phonon branch behaves abnormally; i.e., the group velocity of this phonon branc...

Jin-Wu Jiang

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Optically transparent and environmentally durable superhydrophobic coating based on functionalized SiO 2 nanoparticles

Optical surfaces such as mirrors and windows that are exposed to outdoor environmental conditions are susceptible to dust buildup and water condensation. The application of transparent superhydrophobic coatings on optical surfaces can improve outdoor performance via a ‘self-cleaning’ effect similar to the Lotus effect. The contact angle (CA) of water droplets on a typical hydrophobic flat surface varies from 100° to 120°. Adding roughness or microtexture to a hydrophobic surface leads to an enhancement of hydrophobicity and the CA can be increased to a value in the range of 160°–175°. This result is remarkable because such behavior cannot be explained using surface chemistry alone. When surface features are on the order of 100 nm or smaller, they exhibit superhydrophobic behavior and maintain their optical transparency. In this work we discuss our results on transparent superhydrophobic coatings that can be applied across large surface areas. We have used functionalized silica na...

Daniel A Schaeffer, Georgios Polizos, D Barton Smith, Dominic F Lee, Scott R Hunter and Panos G Datskos

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Room-Temperature Ordered Spin Structures in Cluster-Assembled Single V@Si12 Sheets

The Journal of Physical Chemistry C

DOI: 10.1021/jp508509e

Zhifeng Liu, Xinqiang Wang, Jiangtao Cai and Hengjiang Zhu

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H2O on Graphene/Ir(111): A Periodic Array of Frozen Droplets

The Journal of Physical Chemistry C

DOI: 10.1021/jp510140a

Sebastian Standop, Thomas Michely and Carsten Busse

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MoS2 Quantum Dot: Effects of Passivation, Additional Layer, and h-BN Substrate on Its Stability and Electronic Properties

The Journal of Physical Chemistry C

DOI: 10.1021/jp510598x

G. C. Loh, Ravindra Pandey, Yoke Khin Yap and Shashi P. Karna

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Protonic and Electronic Transport in Hydrated Thin Films of the Pigment Eumelanin

Chemistry of Materials

DOI: 10.1021/cm502939r

Julia Wünsche, Yingxin Deng, Prajwal Kumar, Eduardo Di Mauro, Erik Josberger, Jonathan Sayago, Alessandro Pezzella, Francesca Soavi, Fabio Cicoira, Marco Rolandi and Clara Santato

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Atomic Layer Deposition of AlF3 Thin Films Using Halide Precursors

Chemistry of Materials

DOI: 10.1021/cm504238f

Miia Mäntymäki, Mikko J. Heikkilä, Esa Puukilainen, Kenichiro Mizohata, Benoît Marchand, Jyrki Räisänen, Mikko Ritala and Markku Leskelä

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Localized RNAi Therapeutics of Chemoresistant Grade IV Glioma Using Hyaluronan-Grafted Lipid-Based Nanoparticles

ACS Nano

DOI: 10.1021/nn506248s

Zvi R. Cohen, Srinivas Ramishetti, Naama Peshes-Yaloz, Meir Goldsmith, Anton Wohl, Zion Zibly and Dan Peer

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Spherically-Clustered Porous Au–Ag Alloy Nanoparticle Prepared by Partial Inhibition of Galvanic Replacement and Its Application for Efficient Multimodal Therapy

ACS Nano

DOI: 10.1021/nn506492s

Hongje Jang and Dal-Hee Min

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Engineering Amyloid Fibrils from β-Solenoid Proteins for Biomaterials Applications

ACS Nano

DOI: 10.1021/nn5056089

Maria D.R. Peralta, Arpad Karsai, Alice Ngo, Catherine Sierra, Kai T. Fong, Natha Robert Hayre, Nima Mirzaee, Krishnakumar Mayuram Ravikumar, Alexander J. Kluber, Xi Chen, Gang-yu Liu, Michael D. Toney, Rajiv. R. Singh and Daniel Lee Cox

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Porous C3N4 Nanolayers@N-Graphene Films as Catalyst Electrodes for Highly Efficient Hydrogen Evolution

ACS Nano

DOI: 10.1021/nn506701x

Jingjing Duan, Sheng Chen, Mietek Jaroniec and Shi Zhang Qiao

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Iron Oxide Decorated MoS2 Nanosheets with Double PEGylation for Chelator-Free Radiolabeling and Multimodal Imaging Guided Photothermal Therapy

ACS Nano

DOI: 10.1021/nn506757x

Teng Liu, Sixiang Shi, Chao Liang, Sida Shen, Liang Cheng, Chao Wang, Xuejiao Song, Shreya Goel, Todd E. Barnhart, Weibo Cai and Zhuang Liu

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Effect of Pendant Functionality in Thieno[3,4-b]thiophene-alt-benzodithiophene Polymers for OPVs

Chemistry of Materials

DOI: 10.1021/cm503334h

Patrick Homyak, Yao Liu, Sunzida Ferdous, Feng Liu, Thomas P. Russell and E. Bryan Coughlin

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Strategy for Designing Electron Donors for Thermally Activated Delayed Fluorescence Emitters

The Journal of Physical Chemistry C

DOI: 10.1021/jp511061t

Katsuyuki Shizu, Hiroyuki Tanaka, Motoyuki Uejima, Tohru Sato, Kazuyoshi Tanaka, Hironori Kaji and Chihaya Adachi

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To What Extent Can Surface Morphology Influence the Photoelectrochemical Performance of Au:WO3 Electrodes?

The Journal of Physical Chemistry C

DOI: 10.1021/jp507988c

N. Naseri, M. Qorbani, H. Kim, W. Choi and A. Z. Moshfegh

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Large-Diameter Single-Wall Carbon Nanotubes Formed Alongside Small-Diameter Double-Walled Carbon Nanotubes

The Journal of Physical Chemistry C

DOI: 10.1021/jp509080e

Anne Kasperski, Alicia Weibel, Lucien Datas, Eddy De Grave, Alain Peigney and Christophe Laurent

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Functionalization of Metallic Glasses through Hierarchical Patterning

Nano Letters

DOI: 10.1021/nl504694s

Molla Hasan, Jan Schroers and Golden Kumar

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