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R M Tripathi, Sang J Chung
The biosynthesis of nanomaterials is a huge and intensifying field of research due to their application in various areas, in particular the biomedical and pharmaceutical fields. In this review, we focused on the biosynthesis of both metallic and semiconductor nanomaterials and their application in biomedicine and pharmaceutics. In order to meet an exponentially increasing need for nanostructured materials, the biological route for the synthesis of nanomaterials will have to be explored, offering advantages over chemical and physical methods as a simpler, more cost effective, and environmentally friendly method, and for which there is no need to use high pressure and temperatures or toxic chemicals...
December 12, 2018: Journal of Microbiological Methods
Alei Li, Qianxue Chen, Peipei Wang, Yuan Gan, Tailei Qi, Peng Wang, Fangdong Tang, Judy Z Wu, Rui Chen, Liyuan Zhang, Youpin Gong
2D atomic sheets of transition metal dichalcogenides (TMDs) have a tremendous potential for next-generation optoelectronics since they can be stacked layer-by-layer to form van der Waals (vdW) heterostructures. This allows not only bypassing difficulties in heteroepitaxy of lattice-mismatched semiconductors of desired functionalities but also providing a scheme to design new optoelectronics that can surpass the fundamental limitations on their conventional semiconductor counterparts. Herein, a novel 2D h-BN/p-MoTe2 /graphene/n-SnS2 /h-BN p-g-n junction, fabricated by a layer-by-layer dry transfer, demonstrates high-sensitivity, broadband photodetection at room temperature...
December 14, 2018: Advanced Materials
Wei Shi, Jing Liu, Xiuxia Zhao, Peng Jing, Peng Cheng
As one of the most efficient systems for photocatalytic hydrogen evolution, the Z-scheme system consisting of different semiconductors with a reversible donor-acceptor pair has attracted great attention. Considering for the nontoxicity and low cost of photocatalysts, a series of g-C3N4/α-Fe2O3 hybrids were rationally constructed based on the Z-scheme mechanism for the first time using a metal-organic framework template approach that can fine-tune the compositions and properties of the hybrids. An optimized hybrid, g-C3N4/α-Fe2O3-2, exhibited prominent photocatalytic water splitting performance with a visible light response...
December 13, 2018: Chemistry: a European Journal
Zhongwu Wang, Shujing Guo, Hongwei Li, Bin Wang, Yongtao Sun, Zeyang Xu, Xiaosong Chen, Kunjie Wu, Xiaotao Zhang, Feifei Xing, Liqiang Li, Wenping Hu
The piezoresistive pressure sensor, a kind of widely investigated artificial device to transfer force stimuli to electrical signals, generally consists of one or more kinds of conducting materials. Here, a highly sensitive pressure sensor based on the semiconductor/conductor interface piezoresistive effect is successfully demonstrated by using organic transistor geometry. Because of the efficient combination of the piezoresistive effect and field-effect modulation in a single sensor, this pressure sensor shows excellent performance, such as high sensitivity (514 kPa-1 ), low limit of detection, short response and recovery time, and robust stability...
December 13, 2018: Advanced Materials
Donghun Lee, Haeli Park, Soo Deok Han, Su Han Kim, Woong Huh, Jae Yoon Lee, Yoon Seok Kim, Myung Jin Park, Won Il Park, Chong-Yun Kang, Chul-Ho Lee
Ultralow power chemical sensing is essential toward realizing the Internet of Things. However, electrically driven sensors must consume power to generate an electrical readout. Here, a different class of self-powered chemical sensing platform based on unconventional photovoltaic heterojunctions consisting of a top graphene (Gr) layer in contact with underlying photoactive semiconductors including bulk silicon and layered transition metal dichalcogenides is proposed. Owing to the chemically tunable electrochemical potential of Gr, the built-in potential at the junction is effectively modulated by absorbed gas molecules in a predictable manner depending on their redox characteristics...
December 12, 2018: Small
Kazuo Takimiya, Rukiya Matsidik
Thiophene-annulated naphthalene diimide (NTI)-based molecules have recently emerged as an important class of n-type electronic materials. However, their synthesis has predominantly been achieved by Stille or Suzuki coupling reactions despite the presence of a potential C-H bond in NTI. Additionally, the synthesis of NTI or more generally mono-functionalization of naphthalene diimide (NDI) starts with a cumbersome bromination that has low yield, unselectivity, and tedious purification. We herein thus address these issues via two-step C-H activation; a rhodium-catalyzed direct C-H iodinization is first presented for NDI, followed by establishing an efficient direct arylation protocol for NTI with high yield and robustness...
December 11, 2018: Chemistry, An Asian Journal
Qian Lv, Huan Min, Dong-Ban Duan, Wei Fang, Gui-Ming Pan, Ai-Guo Shen, Qu-Quan Wang, Guangjun Nie, Ji-Ming Hu
Both accurate tumor navigation and nanostructures with high photothermal (PT) conversion efficiency are important but remain challenging to achieve in current biomedical applications. This study reports an anion exchange-based facile and green approach for synthesizing Au@Cu2- x S core-shell nanoparticles (NPs) in an aqueous system. In addition to the PT effect of the suggested NPs, the surface-enhanced Raman scattering (SERS) is also significantly improved due to the tailored localized surface plasmon resonance coupling between the Au metal core and the Cu2- x S semiconductor shell...
December 7, 2018: Advanced Healthcare Materials
Hailong Yan, Ping Yu, Guangchao Han, Qinghua Zhang, Lin Gu, Yuanping Yi, Huibiao Liu, Yuliang Li, Lanqun Mao
The two-dimensional carbon material graphdiyne (GDY) holds great promise as a semiconductor and porous material, however, exfoliation of bulk GDY into single- or few-layered GDY in the aqueous phase remains a challenge. We report an efficient method for the damage-free exfoliation of bulk GDY into single- or few-layered GDY with high yield in an aqueous solution of inorganic salts (e.g., Li2 SiF6 ). This was confirmed by spherical-aberration-corrected scanning transmission electron microscopy, scanning/transmission electron microscopy, atomic force microscopy, Fourier transform infrared/Raman spectroscopy, X-ray photoelectron spectroscopy...
December 7, 2018: Angewandte Chemie
Qingbin Fan, Yilin Wang, Mingze Liu, Ting Xu
Variable-focus lenses are essential elements of optical systems with extensive applications in microscopy, photography, and optical detection. However, conventional varifocal optical systems obtain a limited tunable capability at the expense of bulk size and slow speed. The metasurfaces are two-dimensional flat structures composed of subwavelength scatterers that exhibit the strong potential for developing ultrathin optics. Here we propose and experimentally demonstrate an all-dielectric polarization-multiplexing metalens with the capability to selectively focus polarized light...
December 15, 2018: Optics Letters
A Osman, M Nedeljkovic, J Soler Penades, Y Wu, Z Qu, A Z Khokhar, K Debnath, G Z Mashanovich
Germanium is a material of high interest for mid-infrared (MIR) integrated photonics due to its complementary metal-oxide-semiconductor (CMOS) compatibility and its wide transparency window covering the 2-15 μm spectral region exceeding the 4 and 8 μm limit of the silicon-on-insulator platform and Si material, respectively. In this Letter, we report suspended germanium waveguides operating at a wavelength of 7.67 μm with a propagation loss of 2.6±0.3  dB/cm. To the best of our knowledge, this is the first demonstration of low-loss suspended germanium waveguides at such a long wavelength...
December 15, 2018: Optics Letters
Xuekai Ma, Stefan Schumacher
Vortices are topological objects formed in coherent nonlinear systems. As such they are studied in a wide number of physical systems and promise applications in information storage, processing, and communication. In semiconductor microcavities, vortices in polariton condensates can be conveniently created, studied, and manipulated using solely optical means. For nonresonant excitation with a ring-shaped pump a stable vortex can be formed, leading to bistability with left- and right-handed vorticity. In the present work we report on a much richer vortex multistability, with optically addressable vortices with topological charges m=±1, ±2, and ±3, all stable for the same system and excitation parameters...
November 30, 2018: Physical Review Letters
Bahadur Singh, Barun Ghosh, Chenliang Su, Hsin Lin, Amit Agarwal, Arun Bansil
Materials with tunable charge and lattice degrees of freedom provide excellent platforms for investigating multiple phases that can be controlled via external stimuli. We show how the charge-ordered ferroelectric oxide Ag_{2}BiO_{3}, which has been realized experimentally, presents a unique exemplar of a metal-insulator transition under an external electric field. Our first-principles calculations, combined with a symmetry analysis, reveal the presence of a nearly ideal hourglass-Dirac-semimetal state in the nonpolar structure of Ag_{2}BiO_{3}...
November 30, 2018: Physical Review Letters
He Lin, Xia Long, Yiming An, Dan Zhou, Shihe Yang
A cocatalyst is normally deposited on a photoabsorbing semiconductor (PAS) for photoelectrochemical (PEC) water splitting, but with drawbacks of limited loading, reduced light absorption, and tendency of charge recombination. To tackle these problems, a scheme of three-dimensional (3D) decoupling cocatalysts from the PAS with a pore-spanning crisscross conducting polymer host is proposed in this work. To demonstrate the concept, a facile method was developed for the in situ cogrowth of FeO x nanoparticles and conducting polymer (CP) network in various PAS with different microstructures such as a TiO2 nanorod array, WO3 nanosheet array, and planar TiO2 nanoparticle film, generating the bespoke photoanodes...
December 14, 2018: Nano Letters
Yaguang Guo, Huaiqiu Zhu, Qian Wang
Piezoelectric effects of two-dimensional (2D) group III-V compounds have received considered attention in recent years because of their wide applications in semiconductor devices. However, it faces a problem that only metastable or unstable structures are non-centrosymmetric with piezoelectricity, thus leading to the difficulty in experimental observation. Motivated by the recent advances in the synthesis of 2D group III nitrides, in this paper, for the first time, we study the piezoelectric properties of the 2D group III nitrides (XN, X = Al, Ga, and In) with buckled hexagonal configurations by surface passivation, which are thermodynamically stable...
December 14, 2018: ACS Applied Materials & Interfaces
Clément Livache, Bertille Martinez, Nicolas Goubet, Julien Ramade, Emmanuel Lhuillier
Infrared (IR) sensors based on epitaxially grown semiconductors face two main challenges which are their prohibitive cost and the difficulty to rise the operating temperature. The quest for alternative technologies which will tackle these two difficulties requires the development of new IR active materials. Over the past decade, significant progresses have been achieved. In this perspective, we summarize the current state of the art relative to nanocrystal based IR sensing and stress the main materials, devices and industrial challenges which will have to be addressed over the 5 next years...
2018: Frontiers in Chemistry
Daniel Oran, Samuel G Rodriques, Ruixuan Gao, Shoh Asano, Mark A Skylar-Scott, Fei Chen, Paul W Tillberg, Adam H Marblestone, Edward S Boyden
Lithographic nanofabrication is often limited to successive fabrication of two-dimensional (2D) layers. We present a strategy for the direct assembly of 3D nanomaterials consisting of metals, semiconductors, and biomolecules arranged in virtually any 3D geometry. We used hydrogels as scaffolds for volumetric deposition of materials at defined points in space. We then optically patterned these scaffolds in three dimensions, attached one or more functional materials, and then shrank and dehydrated them in a controlled way to achieve nanoscale feature sizes in a solid substrate...
December 14, 2018: Science
Seungjun Noh, Hao Zhang, Katsuaki Suganuma
In this work, efforts were made to prepare a thermostable die-attach structure which includes stable sintered microporous Ag and multi-layer surface metallization. Silicon carbide particles (SiCp ) were added into the Ag sinter joining paste to improve the high-temperature reliability of the sintered Ag joints. The use of SiCp in the bonding structures prevented the morphological evolution of the microporous structure and maintained a stable structure after high temperature storage (HTS) tests, which reduces the risk of void formation and metallization dewetting...
December 12, 2018: Materials
Dmitriy Yavorskiy, Krzysztof Karpierz, Michał Baj, Małgorzata M Bąk, Nikolai N Mikhailov, Sergey A Dvoretsky, Vladimir I Gavrilenko, Wojciech Knap, Frederic Teppe, Jerzy Usakowski
An epitaxial layer of HgCdTe-a THz detector-was studied in magnetotransmission, magnetoconductivity and magnetophotoconductivity experiments at cryogenic temperatures. In the optical measurements, monochromatic excitation with photon frequency ranging from 0.05 THz to 2.5 THz was used. We show a resonant response of the detector at magnetic fields as small as 10 mT with the width of the resonant line equal to about 5 mT. Application of a circular polarizer at 2.5 THz measurements allowed for confirming selection rules predicted by the theory of optical transitions in a narrow-gap semiconductor and to estimate the band-gap to be equal to about 4...
December 8, 2018: Sensors
Yaxin Wang, Chao Yan, Chunxiang Li, Ziyang Lu, Changchang Ma, Yongsheng Yan, Yongjun Zhang
TiO₂/Ag bilayer films sputtered onto a 2D polystyrene (PS) bead array in a magnetron sputtering system were found to form a nanocap-shaped nanostructure composed of a TiO₂-Ag composite on each PS bead, in which the Ag nanoparticles were trapped partially or fully in the TiO₂ matrix, depending on the TiO₂ thickness. X-ray Photoelectron Spectroscopy (XPS) results showed the opposite shifts of binding energy for Ti 2p and Ag 3d, indicating the transfer of electrons from metallic Ag to TiO₂ owing to the Ag-O-TiO₂ composite formation...
December 7, 2018: Nanomaterials
(no author information available yet)
OBJECTIVEIn this study on the effectiveness and safety of photodynamic therapy (PDT) using talaporfin sodium and a semiconductor laser, the long-term follow-up results of 11 patients with glioblastoma enrolled in the authors' previous phase II clinical trial (March 2009-2012) and the clinical results of 19 consecutive patients with newly diagnosed glioblastoma prospectively enrolled in a postmarket surveillance (March 2014-December 2016) were analyzed and compared with those of 164 patients treated without PDT during the same period...
December 1, 2018: Journal of Neurosurgery
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