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Zongqing Ren, Ziqi Yu, Jae Choon Kim, Jaeho Lee
The trends toward higher power, higher frequency, and smaller scale electronics are making heat dissipation ever more challenging. Passive thermal management based on high thermal conductivity materials or through-silicon vias (TSVs) may not provide sufficient cooling for hot spots reaching 1 kW cm-2 , and active thermal management by thermoelectric cooling (TEC) may require large power consumption or suffer from a large off-state thermal resistance of thermoelectric materials. Here we address these issues by integrating a holey silicon-based TEC with a TSV that directly draws heat from a hot spot to combine active and passive cooling approaches...
November 12, 2018: Nanotechnology
Yifan Chen, Liang Bao, Ning Du, Tao Yang, Qinan Mao, Xiaoxiao Lu, Yangfan Lin, Zhenguo Ji
We demonstrate the in situ synthesis of carbon doped porous silicon (Si/C) nanocomposites by a simple thermal displacement process between Mg2 Si and inorganic gas CO2 in one-step. Via the decomposition of Mg2 Si, the reduction process occurred between Mg and CO2 , leading the uniform doping of many distributed tiny carbon nanoparticles into Si. Meanwhile, the porous structure was formed after an acid treatment. When worked as anodes for lithium-ion batteries, the as-prepared s-porous Si/C nanocomposites exhibited good cycling stability and high-rate capability, which were superior to the porous Si and porous Si/C nanocomposites...
November 12, 2018: Nanotechnology
Qingliang Feng, Meijie Zhu, Yaohua Zhao, Hongyan Liu, Meng Li, Jianbang Zheng, Hua Xu, Yimin Jiang
Monolayer WSe2 exhibits unique optical and electronic properties, showing great potential applications in functional integrated devices, such as electronic devices and optoelectronics. Understanding the growth behavior and process are the key points for the salt-assisted growth of large domain WSe2 monolayers, it is also very important for its further application in on-chip laser and opto-devices. Here, we report a NaCl-assistant method for controlled growth of single crystal monolayer WSe2 with a domain size up to 0...
November 12, 2018: Nanotechnology
Anlian Pan, Kai Zhang, Xinfeng Liu, Cheng-Wei Qiu
No abstract text is available yet for this article.
November 12, 2018: Nanotechnology
Yueshen Wu, Jiaming He, Jinyu Liu, Hui Xing, Zhiqiang Mao, Ying Liu
The effects of dimensional reduction and ion intercalation on superconductivity (SC) in the presence of charge density waves (CDWs) in two-dimensional crystals of 2H-TaSe2 were characterized. We prepared atomically thin crystals by mechanical exfoliation and performed electrical transport measurements on devices made by photolithography. The superconducting transition temperature (T c SC ) was found to increase monotonically as the thickness decreased, changing from 0.14 K in the bulk to higher than 1.4 K for a 3-nm-thick crystal...
November 12, 2018: Nanotechnology
Hongshuai Wu, Chaoqun You, Jia Jiao, Fanghui Chen, Baiwang Sun, Xiaoli Zhu
A combination of photothermal-chemotherapy has received widespread attention in drug delivery systems for cancer treatment. However, the combination therapy operated in subcellular organelles, such as mitochondria, has been rarely reported. Herein, we designed a novel near-infrared (NIR) triggered dual-targeted nanoplatform (FA/TPP-DINPs) based on mitochondrial combined photothermal-chemotherapy by co-loading FDA-approved NIR dye indocyanine green (ICG) and anticancer drug doxorubicin (DOX). The resulting nanoparticles showed a monodispersed sphere and excellent colloidal stability...
November 12, 2018: Nanotechnology
Lingyan Meng, Man Gao, Mengtao Sun
Theoretical calculations were performed for the deep ultraviolet (DUV) tip-enhanced fluorescence (TEF) using Al@Al2 O3 core-shell tips. Fluorescence enhancement, spatial resolution and surface plasmon coupled emission (SPCE) of DUV-TEF were quantitatively studied by finite-difference time-domain (FDTD) method. FDTD results demonstrate that the enhancement factor (EF) of TEF can be as high as 3 orders of magnitudes in the optimal TEF geometry. At the DUV excitation wavelength of 244 nm, the spatial resolution and SPCE angles are 6 nm and ±23°, respectively, showing maximum EF of 7...
November 12, 2018: Nanotechnology
Yukai Chang, Anmin Nie, Shijun Yuan, Bochong Wang, Congpu Mu, Jianyong Xiang, Bingchao Yang, Lei Li, Fusheng Wen, Zhongyuan Liu
Black phosphorus (BP) has recently drawn great attention in the field of electrocatalysis due to its distinct electrocatalytic activity for the oxygen evolution reaction (OER). However, the slow OER kinetics and the poor environmental stability of BP seriously limits its overall OER performance and prevents its electrocatalysis application. Here, sulfur (S)-doped BP nanosheets, which are prepared using high-pressure synthesis followed by liquid exfoliation, have been demonstrated to have much better OER electrocatalytic activity and environmental stability compared to their undoped counterparts...
November 12, 2018: Nanotechnology
Pingping Zhuang, Weiyi Lin, Harry Chou, Anupam Roy, Weiwei Cai, Sanjay K Banerjee
The synthesis of lateral heterostructures assembled by atomically-thin materials with distinct intrinsic properties is important for future heterojunction-embedded two-dimensional (2D) devices. Here we report an etching-assisted chemical vapor deposition method to synthesize large-area continuous lateral graphene/hexagonal boron nitride (Gr/h-BN) heterostructures on carbon-containing copper foils. The h-BN film is first synthesized on the copper foil, followed by hydrogen etching, and then epitaxial graphene domains are grown to form continuous lateral heterostructures...
November 12, 2018: Nanotechnology
Asma Alkabsh, Hassana Samassekou, Dipanjan Mazumdar
Intense interest in transition metal dichalcogenides (TMDs) is driven, among other things, by their intriguing layer-dependent optical properties down to the monolayer and strong excitonic effects. Experimental determination of optical constants such as the complex refractive index and dielectric function of large-area TMDs thin films is prone to large uncertainties at the few-layer level using a single measurement technique such as spectroscopic ellipsometry (SE). In this work, we demonstrate an approach to accurately determine the optical constants by combining transmission spectroscopy with SE...
November 12, 2018: Nanotechnology
Dawn S Y Lin, Feng Guo, Boyang Zhang
Organ-on-a-chip devices, also known as microphysiological systems, have gained significant attention in recent years. Recent advances in tissue engineering and microfabrication have enabled these devices to provide more precise control over cellular microenvironments to mimic the tissue-level or organ-level function of the human body. These more complex tissue models can provide either an improvement in the functional expression and maturation of cells or an avenue to probe biological events and function that would otherwise be difficult to visualize and mechanistically study...
November 5, 2018: Nanotechnology
S Brivio, D Conti, M V Nair, J Frascaroli, E Covi, C Ricciardi, G Indiveri, S Spiga
Spiking neural networks (SNNs) employing memristive synapses are capable of life-long online learning. Because of their ability to process and classify large amounts of data in real-time using compact and low-power electronic systems, they promise a substantial technology breakthrough. However, the critical issue that memristor-based SNNs have to face is the fundamental limitation in their memory capacity due to finite resolution of the synaptic elements, which leads to the replacement of old memories with new ones and to a finite memory lifetime...
October 31, 2018: Nanotechnology
Wei-Hsiang Hua, Cheng-Jin Cai, Keng-Ping Chou, Yu-Hsuan Tsai, Meng Chun Low, Charng-Gan Tu, Chien-Yu Chen, Chia-Chun Ni, Yean-Woei Kiang, C C Yang, Yih-Chih Hsu
For tumor treatment, compared with gold nanoparticles (NPs) of other geometries, a porous gold NP (PGNP) has the advantages of stronger localized surface plasmon resonance (LSPR) due to the pore nanostructures and a larger surface area to link with more drug or photosensitizer (PS) molecules for more effective delivery into cancer cells. Different from the chemical synthesis methods, in this paper we demonstrate the fabrication procedures of PGNP based on shaped Au/Ag deposition on a Si substrate and elucidate the advantageous features...
October 31, 2018: Nanotechnology
Preetam Hazra, K B Jinesh
Resistive Random Access Memory (ReRAM) has emerged as the successor to FLASH in memory technology due to its multi-level fabrication possibilities and prospects of scaling down virtually to atomic dimensions. However, as we report here, when polycrystalline switching materials are used, the ReRAM devices scaled down to the sub-5 nm2 area show complete randomness due to inhomogeneous conductance values of grains and grain boundaries. By measuring the switching properties of grains and grain boundaries individually using a scanning tunneling microscope, we demonstrate that the doublet and triplet grain boundaries behave like degenerate semiconductors and act as conduction channels that bypass the resistive switching of the devices...
October 5, 2018: Nanotechnology
Michael G Ruppert, Steven I Moore, Michal Zawierta, Andrew Fleming, Gino Putrino, Yuen Kuan Yong
Atomic force microscope (AFM) cantilevers with integrated actuation and sensing provide several distinct advantages over conventional cantilever instrumentation. These include clean frequency responses, the possibility of down-scaling and parallelization to cantilever arrays as well as the absence of optical interference. While cantilever microfabrication technology has continuously advanced over the years, the overall design has remained largely unchanged; a passive rectangular shaped cantilever design has been adopted as the industry wide standard...
September 25, 2018: Nanotechnology
Lei Jiang, Chen Su, Shan Ye, Jimin Wu, Zhongjie Zhu, Yanyi Wen, Rui Zhang, Wei Shao
With the high demand for developing novel composites with integrated performance, graphene-based nanostructures have been drawing great attention in environmental and biomedical applications because of their extraordinary physicochemical properties and biocompatibility. Although graphene oxide (GO) nanosheets exhibit some antibacterial activities, novel GO based nanostructures with enhanced antibacterial activities are highly desired. To realize this aim, polyethyleneimine (PEI) modified GO as a tetracycline hydrochloride (TCH) carrier and release platform was constructed (pGO-TCH)...
September 25, 2018: Nanotechnology
Sebastian Heeg, Nick Clark, Aravind Vijayaraghavan
We present a two-step procedure to probe hotspots of plasmon-enhanced Raman scattering with carbon nanotubes (CNTs). Dielectrophoretic deposition places a small CNT bundle on top of a plasmonic Au nanodimer. After 'pre-characterizing' both the nanotubes and dimer structure, we subsequently use the tip of an atomic force microscope to push the bundle into the plasmonic hotspot located in the 25 nm wide dimer gap, characterize its location inside the gap, and observe the onset of plasmon-enhanced Raman scattering...
September 25, 2018: Nanotechnology
Yijun Gao, Robert Patterson, Long Hu, Lin Yuan, Zhilong Zhang, Yicong Hu, Zihan Chen, Zhili Teh, Gavin J Conibeer, Shujuan Huang
The unique tunable bandgaps and straightforward synthesis of colloidal quantum dots make them promising low-cost materials for photovoltaics. High-performance colloidal quantum dot solar cells rely on good-quality electron transporting layers to make carrier selective contacts. Despite extensive use of n-type oxides as electron transporting layers, a detailed understanding of their surface and interface states as well as mechanisms to improve their optical properties are still under development. Here, we report a simple procedure to produce MgCl<sub>2</sub> passivated ZnO nanoparticles electron transporting layers that show improved device performance...
September 24, 2018: Nanotechnology
Jianan Chen, Chang Liu, Yu-Ting Huang, Hyeonseok Lee, Shien-Ping Feng
Highly sensitive and selective non-enzymatic glucose detection was developed using nanoporous Ag flowers on a Ni substrate. The cyclic scanning electrodeposition (CSE) method was used to fabricate Ag flowers on a Ni substrate in an alkaline electrolyte. The nanoporous Ag flowers were then formed by repeated CSE in NaOH. The growth mechanisms of the nanoporous Ag flowers were systematically studied, and these mechanisms can be extended to the formation of other metal, bimetal or metal oxide. The synthesized three-dimensional nanoporous Ag flowers on the Ni substrate were used in the electro-oxidation of glucose, demonstrating a wide linear range (0...
September 21, 2018: Nanotechnology
Christopher Sims, Russell Maier, Aaron Johnston-Peck, Justin Gorham, Vincent A Hackley, Bryant Nelson
Cerium oxide nanomaterials (nanoceria, CNMs) are receiving increased attention from the research community due to their unique chemical properties, most prominent of which is their ability to alternate between the Ce3+ and Ce4+ oxidation states. While many analytical techniques and methods have been employed to characterize the amounts of Ce3+ and Ce4+ present (Ce3+/Ce4+ ratio) within nanoceria materials, to-date no studies have used multiple complementary analytical tools (orthogonal analysis) with technique-independent oxidation state controls for quantitative determinations of the Ce3+/Ce4+ ratio...
September 21, 2018: Nanotechnology
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