Kinetically Controlled Site-Specific Substitutions in Higher-Order Heterostructures

Chemistry of Materials

DOI: 10.1021/acs.chemmater.5b01071

Devin R. Merrill, Duncan R. Sutherland, Jeffrey Ditto, Sage R. Bauers, Matthias Falmbigl, Douglas L. Medlin and David C. Johnson
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Assessment of Strain-Generated Oxygen Vacancies Using SrTiO3 Bicrystals

Nano Letters

DOI: 10.1021/acs.nanolett.5b01245

Si-Young Choi, Sung-Dae Kim, Minseok Choi, Hak-Sung Lee, Jungho Ryu, Naoya Shibata, Teruyasu Mizoguchi, Eita Tochigi, Takahisa Yamamoto, Suk-Joong L. Kang and Yuichi Ikuhara
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Monolayer PtSe2, a New Semiconducting Transition-Metal-Dichalcogenide, Epitaxially Grown by Direct Selenization of Pt

Nano Letters

DOI: 10.1021/acs.nanolett.5b00964

Yeliang Wang, Linfei Li, Wei Yao, Shiru Song, J. T. Sun, Jinbo Pan, Xiao Ren, Chen Li, Eiji Okunishi, Yu-Qi Wang, Eryin Wang, Yan Shao, Y. Y. Zhang, Hai-tao Yang, Eike F. Schwier, Hideaki Iwasawa, Kenya Shimada, Masaki Taniguchi, Zhaohua Cheng, Shuyun Zhou, Shixuan Du, Stephen J. Pennycook, Sokrates T. Pantelides and Hong-Jun Gao
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Impact of Surface-Bound Small Molecules on the Thermoelectric Property of Self-Assembled Ag2Te Nanocrystal Thin Films

Nano Letters

DOI: 10.1021/acs.nanolett.5b00255

Yanming Sun, Haiyu Fang, Lujun Pan, Meng Han, Shen Xu, Xinwei Wang, Biao Xu and Yue Wu
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Reduced Water Vapor Transmission Rate of Graphene Gas Barrier Films for Flexible Organic Field-Effect Transistors

ACS Nano

DOI: 10.1021/acsnano.5b01161

Kyoungjun Choi, Sooji Nam, Youngbin Lee, Mijin Lee, Jaeyoung Jang, Sang Jin Kim, Yong Jin Jeong, Hyeongkeun Kim, Sukang Bae, Ji-Beom Yoo, Sung M. Cho, Jae-Boong Choi, Ho Kyoon Chung, Jong-Hyun Ahn, Chan Eon Park and Byung Hee Hong
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Effects of Substituted Alkyl Chain Length on Solution-Processable Layered Organic Semiconductor Crystals

Chemistry of Materials

DOI: 10.1021/acs.chemmater.5b00810

Satoru Inoue, Hiromi Minemawari, Jun’ya Tsutsumi, Masayuki Chikamatsu, Toshikazu Yamada, Sachio Horiuchi, Mutsuo Tanaka, Reiji Kumai, Makoto Yoneya and Tatsuo Hasegawa
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Electronic confinement in graphene ruled by N doped extended defects

We investigate by means of ab-initio simulations the formation energy and the electronic properties of substitutional N doping in graphene with distinct grain boundary defects as a function of the N concentration. Our results show that the presence of substitutional N atoms along the defective regions is quite likely for several N concentrations. Also, we find either semiconducting or metallic structures, depending on the N concentration. Confinement effects were also investigated for the semiconducting structures. We find that the distance between the defect lines can modulate the band structure of those semiconducting N doped lines. This opens an interesting possibility to produce two-dimensional heterojunctions composed by N doped grain boundaries with different distances between the defect lines.

W H Brito, H Chacham, R Kagimura and R H Miwa

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Nanoscale layer-selective readout of magnetization direction from a magnetic multilayer using a spin-torque oscillator

Technology for detecting the magnetization direction of nanoscale magnetic material is crucial for realizing high-density magnetic recording devices. Conventionally, a magnetoresistive device is used that changes its resistivity in accordance with the direction of the stray field from an objective magnet. However, when several magnets are near such a device, the superposition of stray fields from all the magnets acts on the sensor, preventing selective recognition of their individual magnetization directions. Here we introduce a novel readout method for detecting the magnetization direction of a nanoscale magnet by use of a spin-torque oscillator (STO). The principles behind this method are dynamic dipolar coupling between an STO and a nanoscale magnet, and detection of ferromagnetic resonance (FMR) of this coupled system from the STO signal. Because the STO couples with a specific magnet by tuning the STO oscillation frequency to match its FMR frequency, this readout method can ...

Hirofumi Suto, Tazumi Nagasawa, Kiwamu Kudo, Koichi Mizushima and Rie Sato

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Magnetic force microscopy investigation of arrays of nickel nanowires and nanotubes

The magnetic properties of arrays of nanowires (NWs) and nanotubes (NTs), 150 nm in diameter, electrodeposited inside nanoporous polycarbonate membranes are investigated. The comparison of the nanoscopic magnetic force microscopy (MFM) imaging and the macroscopic behavior as measured by alternating gradient force magnetometry (AGFM) is made. It is shown that MFM is a complementary technique that provides an understanding of the magnetization reversal characteristics at the microscopic scale of individual nanostructures. The local hysteresis loops have been extracted by MFM measurements. The influence of the shape of such elongated nanostructures on the dipolar coupling and consequently on the squareness of the hysteresis curves is demonstrated. It is shown that the nanowires exhibit stronger magnetic interactions than nanotubes. The non-uniformity of the magnetization states is also revealed by combining the MFM and AGFM measurements.

M R Tabasum, F Zighem, J De La Torre Medina, A Encinas, L Piraux and B Nysten

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Mechanism of strain-influenced quantum well thickness reduction in GaN/AlN short-period superlattices

We report on the mechanism of strain-influenced quantum well (QW) thickness reduction in GaN/AlN short-period superlattices grown by plasma-assisted molecular beam epitaxy. Density functional theory was used to support the idea of a thermally activated exchange mechanism between Al adatoms and Ga surface atoms that is influenced by the strain state of the GaN QWs. These ab initio calculations support our experimentally observed reduction in QW thickness for different intrinsic strains.

A V Kuchuk, V P Kladko, T L Petrenko, V P Bryksa, A E Belyaev, Yu I Mazur, M E Ware, E A DeCuir Jr and G J Salamo

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Carbon nanotube electron field emitters for x-ray imaging of human breast cancer

For imaging human breast cancer, digital breast tomosynthesis (DBT) has been shown to improve image quality and breast cancer detection in comparison to two-dimensional (2D) mammography. Current DBT systems have limited spatial resolution and lengthy scan times. Stationary DBT (s-DBT), utilizing an array of carbon nanotube (CNT) field emission x-ray sources, provides increased spatial resolution and potentially faster imaging than current DBT systems. This study presents the results of detailed evaluations of CNT cathodes for x-ray breast imaging tasks. The following were investigated: high current, long-term stability of CNT cathodes for DBT; feasibility of using CNT cathodes to perform a 2D radiograph function; and cathode performance through several years of imaging. Results show that a breast tomosynthesis system using CNT cathodes could run far beyond the experimentally tested lifetime of one to two years. CNT cathodes were found capable of producing higher currents than typ...

Emily Gidcumb, Bo Gao, Jing Shan, Christy Inscoe, Jianping Lu and Otto Zhou

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Localization and electron-electron interactions in few-layer epitaxial graphene

This paper presents a study of the quantum corrections caused by electron-electron interactions and localization to the conductivity in few-layer epitaxial graphene, in which the carriers responsible for transport are massive. The results demonstrate that the diffusive model, which can generally provide good insights into the magnetotransport of two-dimensional systems in conventional semiconductor structures, is applicable to few-layer epitaxial graphene when the unique properties of graphene on the substrate, such as intervalley scattering, are taken into account. It is suggested that magnetic-field-dependent electron-electron interactions and Kondo physics are required for obtaining a thorough understanding of magnetotransport in few-layer epitaxial graphene.

Shun-Tsung Lo, Fan-Hung Liu, Chang-Shun Hsu, Chiashain Chuang, Lung-I Huang, Yasuhiro Fukuyama, Yanfei Yang, Randolph E Elmquist and Chi-Te Liang

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Multi-wall effects on the thermal transport properties of nanotube structures

Understanding the role of inter-layer interactions in multi-walled carbon nanotubes is one of the challenges in the design of potential materials because of their large impact on the physical properties of carbon nanotubes. We focused on the thermal properties of double-walled carbon nanotubes (DWCNTs), which are promising materials due to their high durability and thermal efficiency. We investigated the thermal conductance of DWCNTs by using the nonequilibrium Green’s function method, and found that the quadratic temperature dependence of the thermal conductance at low temperatures consisted of three regions with different tendencies. Based on analysis of the transmission coefficients and the distribution of the normal modes, the three nonuniform regions were attributed to the energy shifts of the normal modes at the low-energy region. We examined the mechanism of these energy shifts using the coupled vibration model with the parameters from our simulations, and elucidated the m...

Tomoyuki Hata, Hiroki Kawai, Ryota Jono and Koichi Yamashita

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Subchronic toxicity and immunotoxicity of MeO-PEG-poly(D,L-lactic-co-glycolic acid)-PEG-OMe triblock copolymer nanoparticles delivered intravenously into rats

Although monomethoxy(polyethyleneglycol)-poly (D,L-lactic-co-glycolic acid)-monomethoxy (PELGE) nanoparticles have been widely studied as a drug delivery system, little is known about their toxicity in vivo . Here we examined the subchronic toxicity and immunotoxicity of different doses of PELGE nanoparticles with diameters of 50 and 200 nm (PELGE50 and PELGE200) in rats. Neither size of PELGE nanoparticles showed obvious subchronic toxic effects during 28 d of continuous intravenous administration based on clinical observation, body weight, hematology parameters and histopathology analysis. PELGE200 nanoparticles showed no overt signs of immunotoxicity based on organ coefficients, histopathology analysis, immunoglobulin levels, blood lymphocyte subpopulations and splenocyte cytokines. Conversely, PELGE50 nanoparticles were associated with an increased organ coefficient and histopathological changes in the spleen, increased serum IgM and IgG levels, alterations in blood lym...

Longfei Liao, Mengtian Zhang, Huan Liu, Xuanmiao Zhang, Zhaolu Xie, Zhirong Zhang, Tao Gong and Xun Sun

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Gadolinium-based nanoparticles for highly efficient T1-weighted magnetic resonance imaging

We developed Pyrene-Gadolinium (Py-Gd) nanoparticles as pH-sensitive magnetic resonance imaging (MRI) contrast agents capable of showing a high-Mr signal in cancer-specific environments, such as acidic conditions. Py-Gd nanoparticles were prepared by coating Py-Gd, which is a complex of gadolinium with pyrenyl molecules, with pyrenyl polyethyleneglycol PEG using a nano-emulsion method. These particles show better longitudinal relaxation time (T1) MR signals in acidic conditions than they do in neutral conditions. Furthermore, the particles exhibit biocompatibility and MR contrast effects in both in vitro and in vivo studies. From these results, we confirm that Py-Gd nanoparticles have the potential to be applied for accurate cancer diagnosis and therapy.

Eun-Kyung Lim, Byunghoon Kang, Yuna Choi, Eunji Jang, Seungmin Han, Kwangyeol Lee, Jin-Suck Suh, Seungjoo Haam and Yong-Min Huh

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Graphynes as Promising Cathode Material of Fuel Cell: Improvement of Oxygen Reduction Efficiency

The Journal of Physical Chemistry C

DOI: 10.1021/jp502780y

Baotao Kang and Jin Yong Lee

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Excitonic and Defect-Related Photoluminescence in Mg3N2

The Journal of Physical Chemistry C

DOI: 10.1021/jp503023t

Yuki Uenaka and Takashi Uchino

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Enhanced Photocatalytic Activity in Low-Temperature Processed Titania Mesoporous Films

The Journal of Physical Chemistry C

DOI: 10.1021/jp501653x

Davide Carboni, Daniela Marongiu, Pietro Rassu, Alessandra Pinna, Heinz Amenitsch, Maria Casula, Augusto Marcelli, Giannantonio Cibin, Paolo Falcaro, Luca Malfatti and Plinio Innocenzi

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Comparison of the Deposition Behavior of Charged Silicon Nanoparticles between Floating and Grounded Substrates

The Journal of Physical Chemistry C

DOI: 10.1021/jp5001144

Woong-Kyu Youn, Sung-Soo Lee, Jae-Young Lee, Chan-Soo Kim, Nong-Moon Hwang and Sumio Iijima

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Effect of Annealing on the First-Cycle Performance and Reversible Capabilities of Lithium-Rich Layered Oxide Cathodes

The Journal of Physical Chemistry C

DOI: 10.1021/jp500138s

Yufang Chen, Zhongxue Chen and Kai Xie

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