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Jia Zhuang, Allison P Young, Chia-Kuang Tsung
Owing to the progressive development of metal-organic-frameworks (MOFs) synthetic processes and considerable potential applications in last decade, integrating biomolecules into MOFs has recently gain considerable attention. Biomolecules, including lipids, oligopeptides, nucleic acids, and proteins have been readily incorporated into MOF systems via versatile formulation methods. The formed biomolecule-MOF hybrid structures have shown promising prospects in various fields, such as antitumor treatment, gene delivery, biomolecular sensing, and nanomotor device...
June 22, 2017: Small
Ning Zhang, Xiyu Li, Yifei Liu, Ran Long, Mengqiao Li, Shuangming Chen, Zeming Qi, Chengming Wang, Li Song, Jun Jiang, Yujie Xiong
Adsorption and activation of molecules on a surface holds the key to heterogeneous catalysis toward aerobic oxidative reactions. To achieve high catalytic activities, a catalyst surface should be rationally tailored to interact with both organic substrates and oxygen molecules. Here, a facile bottom-up approach to defective tungsten oxide hydrate (WO3 ·H2 O) nanosheets that contain both surface defects and lattice water is reported. The defective WO3 ·H2 O nanosheets exhibit excellent catalytic activity for aerobic coupling of amines to imines...
June 22, 2017: Small
Hong-Hua Fang, Loredana Protesescu, Daniel M Balazs, Sampson Adjokatse, Maksym V Kovalenko, Maria Antonietta Loi
The optical properties of the newly developed near-infrared emitting formamidinium lead triiodide (FAPbI3 ) nanocrystals (NCs) and their polycrystalline thin film counterpart are comparatively investigated by means of steady-state and time-resolved photoluminescence. The excitonic emission is dominant in NC ensemble because of the localization of electron-hole pairs. A promisingly high quantum yield above 70%, and a large absorption cross-section (5.2 × 10(-13) cm(-2) ) are measured. At high pump fluence, biexcitonic recombination is observed, featuring a slow recombination lifetime of 0...
June 22, 2017: Small
Yayi Cheng, Jianfeng Huang, Hui Qi, Liyun Cao, Jun Yang, Qiao Xi, Xiaomin Luo, Kazumichi Yanagisawa, Jiayin Li
Carbon nanotubes (CNTs) with excellent electron conductivity are widely used to improve the electrochemical performance of the SnO2 anode. However, the chemical bonding between SnO2 and CNTs is not clearly elucidated despite it may affect the lithiation/delithiation behavior greatly. In this work, an SnO2 @CNT composite with SnC and SnOC bonds as a linkage bridge is reported and the influence of the SnC and SnOC bonds on the lithium storage properties is revealed. It is found that the SnC bond can act as an ultrafast electron transfer path, facilitating the reversible conversion reaction between Sn and Li2 O to form SnO2 ...
June 22, 2017: Small
Timothy U Connell, Stuart K Earl, Charlene Ng, Ann Roberts, Timothy J Davis, Jonathan M White, Anastasios Polyzos, Daniel E Gómez
Modification of the local density of optical states using metallic nanostructures leads to enhancement in the number of emitted quanta and photocatalytic turnover of luminescent materials. In this work, the fabrication of a metamaterial is presented that consists of a nanowire separated from a metallic mirror by a polymer thin film doped with a luminescent organometallic iridium(III) complex. The large spin-orbit coupling of the heavy metal atom results in an excited state with significant magnetic-dipole character...
June 22, 2017: Small
Nicolas Helfricht, Andreas Mark, Marina Behr, Andreas Bernet, Hans-Werner Schmidt, Georg Papastavrou
Hydrogels have many applications in biomedical surface modification and tissue engineering. However, the structuring of hydrogels after their formation represents still a major challenge, in particular due to their softness. Here, a novel approach is presented that is based on the combination of atomic force microscopy (AFM) and nanofluidics, also referred to as FluidFM technology. Its applicability is demonstrated for supramolecular hydrogel films that are prepared from low-molecular weight hydrogelators, such as derivates of 1,3,5-benzene tricarboxamides (BTAs)...
June 22, 2017: Small
Yanyan Xie, Yuefei Wang, Wei Qi, Renliang Huang, Rongxin Su, Zhimin He
Self-assembly of chiral nanostructures is of considerable interest, since the ability to control the chirality of these structures has direct ramifications in biology and materials science. A new approach to design chiral nanostructures from self-assembly of N-(9-fluorenylmethoxycarbonyl)-protected phenylalanine-tryptophan-lysine tripeptides is reported. The terminal charges can induce helical twisting of the assembled β-sheets, enabling the formation of well-defined chiral nanostructures. The degree and direction of twisting in the β-sheets can be precisely tailored through in situ pH and temperature modulations...
June 22, 2017: Small
Mao-Lin Shi, Lin Chen, Tian-Bao Zhang, Jing Xu, Hao Zhu, Qing-Qing Sun, David Wei Zhang
The lack of stable and efficient techniques to synthesize high-quality large-area thin films is one of the major bottlenecks for the real-world application of the 2D transition metal dichalcogenides. In this work, the growth of molybdenum disulfide (MoS2 ) on sapphire substrates by sulfurizing the MoO3 film deposited by atomic layer deposition (ALD) is reported. The advantages of the ALD method can be well inherited, and the synthesized MoS2 films exhibit excellent layer controllability, wafer-scale uniformity, and homogeneity...
June 22, 2017: Small
Dianming Wang, Guoliang Zhang, Yiyang Zhang, Ling Xin, Yuanchen Dong, Yang Liu, Dongsheng Liu
Membrane plays significant role in cellular enzymatic reactions. To better understand its function on membrane integral or bound enzymes, DNA origami and frame-guided assembly strategy are combined to construct a given-size, addressable enzyme-containing nanomembrane as a heterogeneous reactor to explore the enzymatic catalyst reaction on the membrane. The enzymes in the membrane are located precisely. This new kind of membrane can enrich hydrophobic substrate molecules in aqueous solution to the embedded enzymes...
June 22, 2017: Small
Satoshi Yasuda, Ryosuke Takahashi, Ryo Osaka, Ryota Kumagai, Yasumitsu Miyata, Susumu Okada, Yuhei Hayamizu, Kei Murakoshi
Making contact of transition metal dichalcogenides (TMDCs) with a metal surface is essential for fabricating and designing electronic devices and catalytic systems. It also generates strain in the TMDCs that plays significant role in both electronic and phonon structures. Therefore, detailed understanding of mechanism of the strain generation is important to fully comprehend the modulation effect for the electronic and phonon properties. Here, MoS2 and MoSe2 monolayers are grown on Au surface by chemical vapor deposition and it is demonstrated that the contact with a crystalline Au(111) surface gives rise to only out-of-plane strain in both MoS2 and MoSe2 layers, whereas no strain generation is observed on polycrystalline Au or SiO2 /Si surfaces...
June 22, 2017: Small
Xin Lu, M I B Utama, Xingzhi Wang, Weigao Xu, Weijie Zhao, Man Hon Samuel Owen, Qihua Xiong
The gate-tunable phonon properties in bilayer MoS2 are shown to be dependent on excitation energy. Raman intensity, Raman shift, and linewidth are affected by resonant excitation, while a nonresonant laser does not influence the intensity significantly. The gate-dependent Raman shift of A1g mode (either blue-, red-, or no-shift) is a result of the combined effect of antibonding electron and resonant-related decoupling effect. Although the decoupling effect cannot be directly measured due to the resonant background, it can be indirectly and qualitatively probed by observing A1g mode...
June 22, 2017: Small
Mariana Laranjeira, Rui M A Domingues, Raquel Costa-Almeida, Rui L Reis, Manuela E Gomes
Tendon and ligament (T/L) function is intrinsically related with their unique hierarchically and anisotropically organized extracellular matrix. Their natural healing capacity is, however, limited. Here, continuous and aligned electrospun nanofiber threads (CANT) based on synthetic/natural polymer blends mechanically reinforced with cellulose nanocrystals are produced to replicate the nanoscale collagen fibrils grouped into microscale collagen fibers that compose the native T/L. CANT are then incrementally assembled into 3D hierarchical scaffolds, resulting in woven constructions, which simultaneously mimic T/L nano-to-macro architecture, nanotopography, and nonlinear biomechanical behavior...
June 20, 2017: Small
Qingxue Lai, Junjie Zhu, Yingxuan Zhao, Yanyu Liang, Jianping He, Junhong Chen
A transition-metal-nitrogen/carbon (TM-N/C, TM = Fe, Co, Ni, etc.) system is a popular, nonprecious-metal oxygen reduction reaction (ORR) electrocatalyst for fuel cell and metal-air battery applications. However, there remains a lack of comprehensive understanding about the ORR electrocatalytic mechanism on these catalysts, especially the roles of different forms of metal species on electrocatalytic performance. Here, a novel CuN/C ORR electrocatalyst with a hybrid Cu coordination site is successfully fabricated with a simple but efficient metal-organic-framework-based, metal-doping-induced synthesis strategy...
June 19, 2017: Small
Amirhossein Behranginia, Poya Yasaei, Arnab K Majee, Vinod K Sangwan, Fei Long, Cameron J Foss, Tara Foroozan, Shadi Fuladi, Mohammad Reza Hantehzadeh, Reza Shahbazian-Yassar, Mark C Hersam, Zlatan Aksamija, Amin Salehi-Khojin
Reliable fabrication of lateral interfaces between conducting and semiconducting 2D materials is considered a major technological advancement for the next generation of highly packed all-2D electronic circuitry. This study employs seed-free consecutive chemical vapor deposition processes to synthesize high-quality lateral MoS2 -graphene heterostructures and comprehensively investigated their electronic properties through a combination of various experimental techniques and theoretical modeling. These results show that the MoS2 -graphene devices exhibit an order of magnitude higher mobility and lower noise metrics compared to conventional MoS2 -metal devices as a result of energy band rearrangement and smaller Schottky barrier height at the contacts...
June 19, 2017: Small
Yoones Kabiri, Adithya N Ananth, Jaco van der Torre, Allard Katan, Jin-Yong Hong, Sairam Malladi, Jing Kong, Henny Zandbergen, Cees Dekker
While graphene may appear to be the ultimate support membrane for transmission electron microscopy (TEM) imaging of DNA nanostructures, very little is known if it poses an advantage over conventional carbon supports in terms of resolution and contrast. Microscopic investigations are carried out on DNA origami nanoplates that are supported onto freestanding graphene, using advanced TEM techniques, including a new dark-field technique that is recently developed in our lab. TEM images of stained and unstained DNA origami are presented with high contrast on both graphene and amorphous carbon membranes...
June 16, 2017: Small
Yurui Xue, Zicheng Zuo, Yongjun Li, Huibiao Liu, Yuliang Li
The oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and overall water splitting are major energy and chemical conversion efforts. Progress in electrocatalytic reactions have shown that the future is limitless in many fields. However, it is urgent to develop efficient electrocatalysts. Here, the first graphdiyne-supported efficient and bifunctional electrocatalyst is reported using 3D graphdiyne foam as scaffolds, and NiCo2 S4 nanowires as building blocks (NiCo2 S4 NW/GDF). NiCo2 S4 NW/GDF exhibits outstanding catalytic activity and stability toward both OER and HER, as well as overall water splitting in alkaline media...
June 14, 2017: Small
Rong Fan, Xinye Chen, Zihao Wang, David Custer, Jiandi Wan
Electrochemical anodization of titanium (Ti) in a static, bulk condition is used widely to fabricate self-organized TiO2 nanotube arrays. Such bulk approaches, however, require extended anodization times to obtain long TiO2 nanotubes and produce only vertically aligned nanotubes. To date, it remains challenging to develop effective strategies to grow long TiO2 nanotubes in a short period of time, and to control the nanotube orientation. Here, it is shown that the anodic growth of TiO2 nanotubes is significantly enhanced (≈16-20 times faster) under flow conditions in microfluidics...
June 14, 2017: Small
Jinglei Ping, Jacquelyn E Blum, Ramya Vishnubhotla, Amey Vrudhula, Carl H Naylor, Zhaoli Gao, Jeffery G Saven, Alan T Charlie Johnson
Advances in techniques for monitoring pH in complex fluids can have a significant impact on analytical and biomedical applications. This study develops flexible graphene microelectrodes (GEs) for rapid (<5 s), very-low-power (femtowatt) detection of the pH of complex biofluids by measuring real-time Faradaic charge transfer between the GE and a solution at zero electrical bias. For an idealized sample of phosphate buffer solution (PBS), the Faradaic current is varied monotonically and systematically with the pH, with a resolution of ≈0...
June 14, 2017: Small
Xilan Feng, Wang Li, Dapeng Liu, Zheng Zhang, Yang Duan, Yu Zhang
Pd@CeO2 /Al2 O3 catalysts are of great importance for real applications, such as three-way catalysis, CO oxidation, and methane combustion. In this article, the Pd@CeO2 core@shell nanospheres are prepared via the autoredox reaction in aqueous phase. Three kinds of methods are then employed, that is, electrostatic interaction, supramolecular self-assembly, and physical mixing, to support the as-prepared Pd@CeO2 nanospheres on γ-Al2 O3 . A model reaction of catalytic methane-combustion is employed here to evaluate the three Pd@CeO2 /γ-Al2 O3 samples...
June 14, 2017: Small
Lucía Labrador-Páez, Dragana J Jovanović, Manuel I Marqués, Krisjanis Smits, Slobodan D Dolić, Francisco Jaque, Harry Eugene Stanley, Miroslav D Dramićanin, José García-Solé, Patricia Haro-González, Daniel Jaque
Nowadays a large variety of applications are based on solid nanoparticles dispersed in liquids-so called nanofluids. The interaction between the fluid and the nanoparticles plays a decisive role in the physical properties of the nanofluid. A novel approach based on the nonradiative energy transfer between two small luminescent nanocrystals (GdVO4 :Nd(3+) and GdVO4 :Yb(3+) ) dispersed in water is used in this work to investigate how temperature affects both the processes of interaction between nanoparticles and the effect of the fluid on the nanoparticles...
June 12, 2017: Small
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