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ACS Nano

Wei Wang, Jinwen Qin, Zhigang Yin, Minhua Cao
Electrode materials based on conversion reactions with lithium ions generally show much higher energy density. One of the main challenges in the design of these electrode materials is to improve initial Coulombic efficiency and alleviate the volume changes during the lithiation-delithiation processes. Here, we achieve fully reversible conversion in MoO3 as an anode for lithium ion batteries by the hybridization of CoMoO4. The porous MoO3-CoMoO4 microspheres are constructed by homogeneously dispersed MoO3 and CoMoO4 subunits and their lithiation/delithiation processes were studied by ex-situ TEM to reveal the mechanism of the reversible conversion reaction...
November 4, 2016: ACS Nano
S Matthew Menke, Aditya Sadhanala, Mark Nikolka, Niva A Ran, Mahesh Kumar Ravva, Safwat Abdel-Azeim, Hannah L Stern, Ming Wang, Henning Sirringhaus, Thuc-Quyen Nguyen, Jean-Luc Brédas, Guillermo C Bazan, Richard H Friend
Donor-acceptor organic solar cells often show high quantum yields for charge collection, but relatively low open-circuit voltages (VOC) limit power conversion efficiencies to around 12%. We report here the behavior of a system, PIPCP:PC61BM, that exhibits very low electronic disorder (Urbach energy less than 27 meV), very high carrier mobilities in the blend (field-effect mobility for holes >10(-2) cm(2) V(-1) s(-1)), and a very low driving energy for initial charge separation (50 meV). These characteristics should give excellent performance, and indeed, the VOC is high relative to the donor energy gap...
November 3, 2016: ACS Nano
Zheng-Ze Pan, Hirotomo Nishihara, Shinichiroh Iwamura, Takafumi Sekiguchi, Akihiro Sato, Akira Isogai, Feiyu Kang, Takashi Kyotani, Quan-Hong Yang
Honeycomb structures have been attracting the attention from researchers mainly for its high strength-to-weight ratio. As one of its kind, honeycomb monoliths having microscopically dimensioned channels have recently gained lots of achievements since its emergence. Inspired by the microhoneycomb structure that occurs in the natural tree xylems, we have been focusing on the assembly of such structure by using the major component in the tree xylem - cellulose, as the starting material. Through the path that has finally led us to the success of the reconstruction of tree xylems by the unidirectional freeze-drying (UDF) approach, we verified the function of cellulose nanofibers, towards forming xylem-like monolith (XM)...
November 3, 2016: ACS Nano
Alexander Klaiber, Sebastian Polarz
The solvent-mediated ability for molecularly-encoded self-assembly into states of higher order (micelles, lyotropic liquid-crystals) embodies the basis for many applications of surfactants in science and society. Surfactants are used frequently in recipes for nanoparticle synthesis. Because ordinary surfactants comprise insulating constituents (alkyl-groups as side-chains and charged organic heads) such nanostructures are wrapped in an electrically inactive barrier, and this is a large disadvantage for future developments in nanotechnology...
November 3, 2016: ACS Nano
Yulin Oh, Ju Won Lim, Jae Geun Kim, Huan Wang, Byung-Hyun Kang, Young Wook Park, Heejun Kim, Yu Jin Jang, Jihyeon Kim, Dong Ha Kim, Byeong-Kwon Ju
In this study, we demonstrate a viable and promising optical engineering technique enabling the development of high-performance plasmonic organic photovoltaic devices. Laser interference lithography was explored to fabricate metal nanodot (MND) arrays with elaborately controlled dot size as well as periodicity, allowing the spectral overlap between the absorption range of the active layers and the surface plasmon band of MND arrays. MND arrays with ~91 nm dot size and ~202 nm periodicity embedded in poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) hole transport layer remarkably enhanced the average power conversion efficiency (PCE) from 7...
November 3, 2016: ACS Nano
Enrique D Cobas, Olaf M J Van't Erve, Shu-Fan Cheng, James C Culbertson, Glenn G Jernigan, Konrad Bussman, Berend T Jonker
We report room temperature negative magnetoresistance in ferromagnet-graphene-ferromagnet (FM-Gr-FM) junctions with minority spin polarization exceeding 80%, consistent with predictions of strong minority-spin filtering. We fabricated arrays of such junctions via chemical vapor deposition of graphene on lattice-matched single-crystal NiFe(111) films and standard photolithographic patterning and etching techniques. The junctions exhibit metallic transport behavior, low resistance, and the negative magnetoresistance characteristic of a minority spin filter interface throughout the temperature range 10K to 300K...
November 2, 2016: ACS Nano
Bo-Kyeong Jung, Yeon Kyung Lee, Jinwoo Hong, Hamidreza Ghandehari, Chae-Ok Yun
Oncolytic adenovirus (Ad) is a promising candidate for cancer gene therapy. However, as a monotherapy it has shown insufficient therapeutic efficacy in clinical trials. In this work we demonstrate that gold nanorod (GNR)-mediated mild hyperthermia enhances the cellular uptake and consequent gene expression of oncolytic Ad to head and neck tumor cells. We examined the combination of oncolytic Ad expressing vascular endothelial growth factor (VEGF) promoter-targeted artificial transcriptional repressor zinc-finger protein and GNR-mediated mild hyperthermia to improve antitumor effect...
November 2, 2016: ACS Nano
Konstantin V Reich, Boris I Shklovskii
Recently, epitaxially connected at facets semiconductor nanocrystals (NCs) have been introduced to fascilitate the electron transport between nanocrystals. To fully deploy their potential a better understanding of the exciton transfer between connected NCs is needed. We go beyond the two well-known transfer mechanisms suggested by Förster and Dexter and propose a third mechanism of exciton tandem tunneling. The tandem tunnelling occurs through the intermediate state in which electron and hole are in different NCs...
November 2, 2016: ACS Nano
Filippo Bertoli, David Garry, Marco P Monopoli, Anna Salvati, Kenneth A Dawson
It has been well established that the early stages of nanoparticle-cell interactions are governed, at least in part, by the layer of proteins and other biomolecules adsorbed and slowly exchanged with the surrounding biological media (biomolecular corona). Subsequent to membrane interactions, nanoparticles are typically internalized into the cell and trafficked along defined pathways such as, in many cases, the endolysosomal pathway. Indeed, if the original corona is partially retained on the nanoparticle surface, the biomolecules in this layer may play an important role in determining subsequent cellular processing...
November 2, 2016: ACS Nano
Yiwen Li, Yijun Xie, Zhao Wang, Nanzhi Zang, Fabio Carniato, Yuran Huang, Christopher M Andolina, Lucas R Parent, Treffly B Ditri, Eric D Walter, Mauro Botta, Jeffrey D Rinehart, Nathan C Gianneschi
We describe a synthetic method for increasing and controlling the iron loading of synthetic melanin nanoparticles and use the resulting materials to perform a systematic quantitative investigation on their structure-property relationship. A comprehensive analysis by magnetometry, electron paramagnetic resonance, and nuclear magnetic relaxation dispersion reveals the complexities of their magnetic behavior and how these intraparticle magnetic interactions manifest in useful material properties such as their performance as MRI contrast agents...
November 1, 2016: ACS Nano
He Tian, Bingchen Deng, Matthew L Chin, Xiaodong Yan, Hao Jiang, Shu-Jen Han, Vivian Sun, Qiangfei Xia, Madan Dubey, Fengnian Xia, Han Wang
Nonvolatile charge-trap memory plays an important role in many modern electronics technologies, from portable electronic systems to large-scale data centers. Conventional charge-trap memory devices typically work with fixed channel carrier polarity and device characteristics. However, many emerging applications in reconfigurable electronics and neuromorphic computing require dynamically tunable properties in their electronic device components that can lead to enhanced circuit versatility and system functionalities...
November 1, 2016: ACS Nano
Kewei Zhang, Zhong Lin Wang, Ya Yang
The pyro-phototronic effect is based on the coupling among photoexcitation, pyroelectricity, and semiconductor charge transport in pyroelectric materials, which can be utilized to modulate photoexcited carriers to enhance the output performance of solar cells. Herein, we have demonstrated the largely enhanced output performance of a P3HT/ZnO nanowire array photovoltaic cell (PVC) by using the pyro-phototronic effect under weak light illuminations. By applying an external cooling temperature variation, the output current and voltage of the PVC can be dramatically enhanced by 18% and 152% under indoor light illumination, respectively...
November 1, 2016: ACS Nano
Feifei Xia, Zhibin Shao, Yuanyuan He, Rongbin Wang, Xiaofeng Wu, Tianhao Jiang, Steffen Duhm, Jianwei Zhao, Shuit-Tong Lee, Jiansheng Jie
Wide bandgap II-VI nanostructures are important building blocks for new-generation electronic and optoelectronic devices. However, the difficulty of realizing p-type conductivity in these materials via conventional doping methods has severely handicapped the fabrication of p-n homojunctions and complementary circuits, which are the fundamental components for high-performance devices. Herein, by using first-principles density functional theory (DFT) calculations, we demonstrated a simple yet efficient way to achieve controlled p-type doping on II-VI nanostructures via surface charge transfer doping (SCTD) using high work-function transition metal oxides such as MoO3, WO3, CrO3, and V2O5 as dopants...
October 31, 2016: ACS Nano
Hsin-Hui Huang, Zijian Hong, Huolin L Xin, Dong Su, Long-Qing Chen, Guanzhong Huang, Paul R Munroe, Nagarajan Valanoor
The nanoscale origins of ferroelastic domain wall motion in ferroelectric multilayer thin films that lead to giant electromechanical responses are investigated. We present direct evidence for complex underpinning factors that result in ferroelastic domain wall mobility using a combination of atomic-level aberration corrected scanning transmission electron microscopy and phase-field simulations in model epitaxial (001) tetragonal (T) PbZrxTi1-xO3 (PZT)/rhombohedral (R) PbZrxTi1-xO3 (PZT) bilayer heterostructures...
October 31, 2016: ACS Nano
Anderson David Smith, Frank Niklaus, Alan Paussa, Stephan Schroeder, Andreas C Fischer, Mikael Sterner, Stefan Wagner, Sam Vaziri, Fredrik Forsberg, David Esseni, Mikael Ostling, Max C Lemme
Graphene membranes act as highly sensitive transducers in nanoelectromechanical devices due to their ultimate thinness. Previously, the piezoresistive effect has been experimentally verified in graphene using uniaxial strain in graphene. Here we report experimental and theoretical data on the uni- and biaxial piezoresistive properties of suspended graphene membranes applied to piezoresistive pressure sensors. A detailed model that utilizes a linearized Boltzman transport equation describes accurately the charge carrier density and mobility in strained graphene, and hence the gauge factor...
October 31, 2016: ACS Nano
Henan Li, Peng Li, Jing-Kai Huang, Ming-Yang Li, Chih-Wen Yang, Yumeng Shi, Xi-Xiang Zhang, Lain-Jong Li
Two-dimensional transition metal dichalcogenides (TMDCs) have shown great promise in electronics and optoelectronics due to their unique electrical and optical properties. Heterostructured TMDC layers such as the laterally stitched TMDCs offer the advantages of better electronic contact and easier band offset tuning. Here, we demonstrate a photoresist-free focus ion beam method to pattern as-grown TMDC monolayers by chemical vapor deposition, where the exposed edges from FIB etching serve as the seeds for growing a second TMDC material to form desired lateral heterostructures with arbitrary layouts...
October 31, 2016: ACS Nano
Keivan Esfarjani, Hsiao-Fang Lee, Zhizhong Dong, Gang Xiong, Assimina A Pelegri, Stephen D Tse
The relative stability and melting of cubic boron nitride (c-BN) nanoparticles of varying shapes and sizes are studied using classical molecular dynamics (MD) simulation. Focusing on the melting of octahedral c-BN nanoparticles, which consist solely of the most stable {111} facets, decomposition is observed to occur during melting, along with the formation of phase segregated boron clusters inside the c-BN nanoparticles, concurrent with vaporization of surface nitrogen atoms. To assess this MD prediction, a laser-heating experiment of c-BN powders is conducted, manifesting boron clusters for the post-treated powders...
October 31, 2016: ACS Nano
Yifan Wang, Jianglin Wang, Hang Hao, Mingle Cai, Shiyao Wang, Jun Ma, Yan Li, Chuanbin Mao, Shengmin Zhang
Biocompatible tissue-borne crystalline nanoparticles releasing anticancer therapeutic inorganic elements are intriguing therapeutics holding the promise for both tissue repair and cancer therapy. However, how the therapeutic inorganic elements released from the lattice of such nanoparticles induce tumor inhibition remains unclear. Here we use selenium-doped hydroxyapatite nanoparticles (Se-HANs), which could potentially fill the bone defect generated from bone tumor removal while killing residual tumor cells, as an example to study the mechanism by which selenium released from the lattice of Se-HANs induces apoptosis of bone cancer cells in vitro and inhibits the growth of bone tumors in vivo...
October 31, 2016: ACS Nano
Seema Pande, Wei Huang, Nan Shao, Lei-Ming Wang, Navneet Singh Khetrapal, Wai-Ning Mei, Tian Jian, Lai-Sheng Wang, Xiao Cheng Zeng
Gold nanoclusters have attracted great attentions in the past decade due to their remarkable size-dependent electronic, optical, and catalytic properties. However, the structures of large gold clusters are still not well known because of the challenges in global structural searches. Here we report a joint photoelectron spectroscopy (PES) and theoretical study of the structural evolution of negatively-charged core-shell gold nanoclusters (Aun-) for n = 42 to 50. Photoelectron spectra of size-selected Aun- clusters are well resolved with distinct spectral features, suggesting a dominating structural type...
October 30, 2016: ACS Nano
Emiliano Cortés, Paloma Arroyo Huidobro, Hugo G Sinclair, Stina Guldbrand, William J Peveler, Timothy Davies, Simona Parrinello, Frederik Görlitz, Chris Dunsby, Mark A A Neil, Yonatan Sivan, Ivan P Parkin, Paul M W French, Stefan A Maier
Plasmonic nanoparticles influence the absorption and emission processes of nearby emitters due to local enhancements of the illuminating radiation and the photonic density of states. Here, we use the plasmon resonance of metal nanoparticles in order to enhance the stimulated depletion of excited molecules for super-resolved nanoscopy. We demonstrate stimulated emission depletion (STED) nanoscopy with gold nanorods with a long axis of only 26 nm and a width of 8 nm that provide an enhancement of up to 50% of the resolution compared to fluorescent-only probes without plasmonic components irradiated with the same depletion power...
October 30, 2016: ACS Nano
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