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1.
The strong hydrogen bonding ability of 2-pyridones were exploited to build nanotrains on surfaces. Carborane wheels on axles
difunctionalized with 2-pyridone hydrogen bonding units were synthesized and displayed spontaneous formation of linear nanotrains
by self-assembly on SiO2 or mica surfaces. Imaging using atomic force microscopy confirmed linear formations with lengths up to 5 μm and heights within
the range of the molecular height of the carborance-tipped axles.
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2.
Two simple methods have been demonstrated to obtain large area, single crystalline lamellae of copper-7,7,8,8-tetracyanoquinodimethane
(CuTCNQ). The formation of the lamellae was a result of fine tuning of the processes during the synthesis processes of CuTCNQ
phase II. This facile synthesis of large area single crystalline lamellae suggests bright prospects for the study and understanding
of the electrical switching of CuTCNQ by using single crystals of its phase II, and future applications of the material in
memory and switching devices.
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3.
Aravind Vijayaraghavan Sabine Blatt Christoph Marquardt Simone Dehm Raghav Wahi Frank Hennrich Ralph Krupke 《Nano Research》2008,1(4):321-332
We introduce voltage-contrast scanning electron microscopy (VC-SEM) for visual characterization of the electronic properties
of single-walled carbon nanotubes. VC-SEM involves tuning the electronic band structure and imaging the potential profi le
along the length of the nanotube. The resultant secondary electron contrast allows to distinguish between metallic and semiconducting
carbon nanotubes and to follow the switching of semiconducting nanotube devices, as confi rmed by in situ electrical transport
measurements. We demonstrate that high-density arrays of individual nanotube devices can be rapidly and simultaneously characterized.
A leakage current model in combination with fi nite element simulations of the device electrostatics is presented in order
to explain the observed contrast evolution of the nanotube and surface electrodes. This work serves to fill a void in electronic
characterization of molecular device architectures.
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4.
Using magnetic nanoparticles to enhance gene transfection, a recently developed technique termed magnetofection, has been
shown to be a powerful technology in gene delivery. The most widely used magnetic nanoparticles in this area are those coated
with polyethyleneimine, which is a well known nonviral transfection agent. In this article, we report methods to control the
aggregate size of polyethyleneimine-coated magnetite particles. These particles were then used to enhance transfection of
green fluorescent protein (GFP) into NIH 3T3 cells in vitro. We find that the aggregate size of the particles has a great effect on their performance in magnetofection, with less aggregated
magnetic particles being more effective in enhancing the gene transfection.
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5.
The plastic deformation and the ultrahigh strength of metals at the nanoscale have been predicted to be controlled by surface
dislocation nucleation. In situ quantitative tensile tests on individual 〈111〉 single crystalline ultrathin gold nanowires have been performed and significant
load drops observed in stress-strain curves suggest the occurrence of such dislocation nucleation. High-resolution transmission
electron microscopy (HRTEM) imaging and molecular dynamics simulations demonstrated that plastic deformation was indeed initiated
and dominated by surface dislocation nucleation, mediating ultrahigh yield and fracture strength in sub-10-nm gold nanowires.
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6.
Zhongwei Niu Saswat Kabisatpathy Jinbo He L. Andrew Lee Jianhua Rong Lin Yang Godfrey Sikha Branko N. Popov Todd S. Emrick Thomas P. Russell Qian Wang 《Nano Research》2009,2(6):474-483
A sol-gel process has been developed to incorporate bionanoparticles, such as turnip yellow mosaic virus, cowpea mosaic virus,
tobacco mosaic virus, and ferritin into silica, while maintaining the integrity and morphology of the particles. The structures
of the resulting materials were characterized by transmission electron microscopy, small angle X-ray scattering, and N2 adsorption-desorption analysis. The results show that the shape and surface morphology of the bionanoparticles are largely
preserved after being embedded into silica. After removal of the bionanoparticles by calcination, mesoporous silica with monodisperse
pores, having the shape and surface morphology of the bionanoparticles replicated inside the silica, was produced,. This study
is expected to lead to both functional composite materials and mesoporous silica with structurally well-defined large pores.
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7.
Hongwang Zhang Savas Delikanli Yueling Qin Shuli He Mark Swihart Hao Zeng 《Nano Research》2008,1(4):314-320
Semiconductor nanocrystals (dots, rods, wires, etc.) exhibit a wide range of electrical and optical properties that differ
from those of the corresponding bulk materials. These properties depend on both nanocrystal size and shape. Compared with
nanodots, nanorods have an additional degree of freedom, the length or aspect ratio, and reduced symmetry, which leads to
anisotropic properties. In this paper, we report the Au nanoparticlecatalyzed colloidal synthesis of monodisperse CdS nanorods.
Based on systematic high resolution transmission electron microscopy studies, we propose a growth mechanism for these nanorods.
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8.
Yunfeng Zhao Yan Fan Xiaoyue Mu Hongze Gao Jia Wang Jingying Zhang Wensheng Yang Lifeng Chi Yue Wang 《Nano Research》2009,2(6):493-499
It is a great challenge to spontaneously assemble achiral molecules into twisted nanostructures in the absence of chiral substances.
Here we show that two achiral centrosymmetric quinacridone (QA) derivatives, N,N′-di(n-hexyl)-1, 3, 8, 10-tetramethylquinacridone (C6TMQA) and N,N′-di(n-decyl)-1, 3, 8, 10-tetramethylquinac ridone (C10TMQA), can be employed as building blocks to fabricate well-defined twisted
nanostructures by controlling the solvent composition and concentration. Bowknot-like bundles with twisted fiber arms were
prepared from C6TMQA, whilst uniform twisted fibers were generated from C10TMQA in ethanol/THF solution. Spectroscopic characterization
and molecular simulation calculations revealed that the introduction of ethanol into the solution could induce a staggered
aggregation of C6TMQA (or C10TMQA) molecules and the formation of twisted nanostructures. Such twisted materials generated
from achiral organic functional molecules may be valuable in the design and fabrication of new materials for optoelectronic
applications.
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9.
Bimetallic PtAu heteronanostructures have been synthesized from Pt-on-Au nanoparticles, which were made from platinum acetylacetonate
and gold nanoparticles. Using the Pt-on-Au nanoparticles as precursors, Ptsurface rich PtAu bimetallic heteronanostructures
can be produced through controlled thermal treatments, as confirmed by field emission high-resolution transmission electron
microscopy (HR-TEM) and elemental mapping using a high-angle annular dark-field scanning transmission electron microscope
(HAADF-STEM). Oxidation of formic acid was used as a model reaction to demonstrate the effects of varying composition and
surface structure on the catalytic performance of PtAu bimetallic nanostructures. Cyclic voltammetry (CV) showed that these
carbon-supported PtAu heteronanostructures were much more active than platinum in catalyzing the oxidation of formic acid,
judging by the mass current density. The results showed that postsynthesis modification can be a very useful approach to the
control of composition distributions in alloy nanostructures.
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10.
Bi<Subscript>2</Subscript>S<Subscript>3</Subscript> nanostructures: A new photocatalyst 总被引:2,自引:0,他引:2
Uniform colloidal Bi2S3 nanodots and nanorods with different sizes have been prepared in a controllable manner via a hot injection method. X-ray
diffraction (XRD) results show that the resulting nanocrystals have an orthorhombic structure. Both the diameter and length
of the nanorods increase with increasing concentration of the precursors. All of the prepared Bi2S3 nanostructures show high efficiency in the photodegradation of rhodamine B, especially in the case of small sized nanodots—which
is possibly due to their high surface area. The dynamics of the photocatalysis is also discussed.
相似文献
11.
Juan Yan Mei Hu Di Li Yao He Rui Zhao Xingyu Jiang Shiping Song Lianhui Wang Chunhai Fan 《Nano Research》2008,1(6):490-496
A novel nano- and micro-integrated protein chip (NMIPC) that can detect proteins with ultrahigh sensitivity has been fabricated.
A microfluidic network (μFN) was used to construct the protein chips, which allowed facile patterning of proteins and subsequent
biomolecular recognition. Aqueous phase-synthesized, water-soluble fluorescent CdTe/CdS core-shell quantum dots (aqQDs), having
high quantum yield and high photostability, were used as the signaling probe. Importantly, it was found that aqQDs were compatible
with microfluidic format assays, which afforded highly sensitive protein chips for cancer biomarker assays.
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12.
Albert G. Nasibulin Simas Rackauskas Hua Jiang Ying Tian Prasantha Reddy Mudimela Sergey D. Shandakov Larisa I. Nasibulina Sainio Jani Esko I. Kauppinen 《Nano Research》2009,2(5):373-379
We propose a simple method for the efficient and rapid synthesis of one-dimensional hematite (α-Fe2O3) nanostructures based on electrical resistive heating of iron wire under ambient conditions. Typically, 1–5 μm long α-Fe2O3 nanowires were synthesized on a time scale of seconds at temperatures of around 700 ° ⊂. The morphology, structure, and mechanism
of formation of the nanowires were studied by scanning and transmission electron microscopies, energy dispersive X-ray spectroscopy,
X-ray photoelectron spectroscopy, and Raman techniques. A nanowire growth mechanism based on diffusion of iron ions to the
surface through grain boundaries and to the growing wire tip through stacking fault defects and due to surface diffusion is
proposed.
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13.
Synthesis of high magnetic moment CoFe nanoparticles via interfacial diffusion in core/shell structured Co/Fe nanoparticles 总被引:1,自引:0,他引:1
We report the synthesis of high magnetic moment CoFe nanoparticles via the diffusion of Co and Fe in core/shell structured
Co/Fe nanoparticles. In an organic solution, Co nanoparticles were coated with a layer of Fe to form a Co/Fe core/shell structure.
Further raising the solution temperature led to inter-diffusion of Co and Fe and formation of CoFe alloy nanoparticles. These
nanoparticles have high saturation magnetization of up to 192 emu/g CoFe and can be further stabilized by thermal annealing
at 600 °C.
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These two authors made an equal contribution to the work. 相似文献
14.
Current methods of synthesizing single-walled carbon nanotubes (SWNTs) result in racemic mixtures that have impeded the study
of left- and right-handed SWNTs. Here we present a method of isolating different SWNT enantiomers using density gradient ultracentrifugation.
Enantiomer separation is enabled by the chiral surfactant sodium cholate, which discriminates between left- and right-handed
SWNTs and thus induces subtle differences in their buoyant densities. This sorting strategy can be employed for simultaneous
enrichment by handedness and roll-up vector of SWNTs having diameters ranging from 0.7 to 1.5 nm. In addition, circular dichroism
of enantiomer refined samples enables identification of high-energy optical transitions in SWNTs.
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15.
We demonstrate that the near-infrared (NIR) absorptivity of semiconducting single-walled carbon nanotubes (s-SWCNTs) can be
harnessed in blended heterojunctions with the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). Photogenerated charge separation is efficiently driven by the ultrahigh interfacial area
of the blends and the favorable energy offsets between the two materials. NIR-sensitive photovoltaic and photodetector devices
utilizing the stack (indium tin oxide/ca. 10 nm s-SWCNT:PCBM/100 nm C60/10 nm 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/Ag) were fabricated with NIR power conversion efficiencies >1.3%
and peak, zero bias external quantum efficiency of 18% at λ = 1205 nm.
相似文献
16.
17.
Franziska Schäffel Jamie H. Warner Alicja Bachmatiuk Bernd Rellinghaus Bernd Büchner Ludwig Schultz Mark H. Rümmeli 《Nano Research》2009,2(9):695-705
The controlled etching of graphite and graphene by catalytic hydrogenation is potentially a key engineering route for the
fabrication of graphene nanoribbons with atomic precision. The hydrogenation mechanism, though, remains poorly understood.
In this study we exploit the benefits of aberration-corrected high-resolution transmission electron microscopy to gain insight
to the hydrogenation reaction. The etch tracks are found to be commensurate with the graphite lattice. Catalyst particles
at the head of an etch channel are shown to be faceted and the angles between facets are multiples of 30°. Thus, the angles
between facets are also commensurate with the graphite lattice. In addition, the results of a post-annealing step suggest
that all catalyst particles—even if they are not involved in etching—are actively forming methane during the hydrogenation
reaction. Furthermore, the data point against carbon dissolution being a key mechanism during the hydrogenation process.
相似文献
18.
Madathumpady Abubaker Habeeb Muhammed Subramani Ramesh Sudarson Sekhar Sinha Samir Kumar Pal Thalappil Pradeep 《Nano Research》2008,1(4):333-340
Two fluorescent quantum clusters of gold, namely Au25 and Au8, have been synthesized from mercaptosuccinic acid-protected gold nanoparticles of 4–5 nm core diameter by etching with excess
glutathione. While etching at pH ∼3 yielded Au25, that at pH 7–8 yielded Au8. This is the first report of the synthesis of two quantum clusters starting from a single precursor. This simple method makes
it possible to synthesize well-defined clusters in gram quantities. Since these clusters are highly fluorescent and are highly
biocompatible due to their low metallic content, they can be used for diagnostic applications.
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19.
Christine H. Moran Sean M. Wainerdi Tonya K. Cherukuri Carter Kittrell Benjamin J. Wiley Nolan W. Nicholas Steven A. Curley John S. Kanzius Paul Cherukuri 《Nano Research》2009,2(5):400-405
Capacitively coupled shortwave radiofrequency fields (13.56 MHz) resistively heat low concentrations (∼1 ppm) of gold nanoparticles
with a thermal power dissipation of ∼380 kW/g of gold. Smaller diameter gold nanoparticles (< 50 nm) heat at nearly twice
the rate of larger diameter gold nanoparticles (≥50 nm), which is attributed to the higher resistivity of smaller gold nanostructures.
A Joule heating model has been developed to explain this phenomenon and provides critical insights into the rational design
and engineering of nanoscale materials for noninvasive thermal therapy of cancer.
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These two authors made an equal contribution to the work. 相似文献
20.
Ernesto Joselevich 《Nano Research》2009,2(10):743-754
The organization of carbon nanotubes into well-defined straight or curved geometries and arrays on surfaces is a critical
prerequisite for their integration into nanocircuits and a variety of functional nanosystems. We review the recent development
of a new approach to carbon nanotube organization based on self-organized growth directed by well-defined crystal surfaces,
or “nanotube epitaxy”. We identify three different modes of surface-directed growth, namely by atomic rows, atomic steps,
and nanofacets. Particular emphasis is given here to the combinations of such surface-directed growth with external forces—like
those exerted by an electric field or gas flow—for the creation of well-defined complex geometries, including crossbar architectures,
serpentines, and coils.
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