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nano catalysis

Bin Li, Liansheng Qiao, Lingling Li, Yanling Zhang, Kai Li, Lingzhi Wang, Yanjiang Qiao
Our previous studies have shown that Coix glutelin pepsin hydrolysate can effectively inhibit angiotensin converting enzyme (ACE) activity in vitro. The main purpose of this study was to obtain potent anti-hypertensive peptides from Coix glutelin. The Coix glutelin hydrolysates (CGH) were prepared by pepsin catalysis and further separated by an ultrafitration (UF) system, gel filtration chromatography (GFC) and reversed-phase high performance liquid chromatography (RP-HPLC). As a result, the sub-fraction F5-3 had the highest ACE-inhibitory activity...
January 13, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Haiyan Zhu, Yawei Li, Guizhi Zhu, Haibin Su, Siew Hwa Chan, Qiang Sun
An efficient conversion of CO2 into valuable fuels and chemicals has been hotly pursued recently. Here, for the first time, we have explored a series of M12x12 nano-cages (M = B, Al, Be, Mg; X = N, P, O) for catalysis of CO2 to HCOOH. Two steps are identified in the hydrogenation process, namely, H2 activation to 2H*, and then 2H* transfer to CO2 forming HCOOH, where the barriers of two H* transfer are lower than that of the H2 activation reaction. Among the studied cages, Be12O12 is found to have the lowest barrier in the whole reaction process, showing two kinds of reaction mechanisms for 2H* (simultaneous transfer and a step-wise transfer with a quite low barrier)...
January 18, 2017: Scientific Reports
Ahmed Mohsen Ismail, Mahmoud Mohamed Emara, Taher Salah El Din Kassem, Mahmoud Ahmed Moussa
CuO nanostructures (NSs) of different morphologies were prepared, applied as catalysts for the pyrolysis of sugarcane bagasse (PSCB), and applied for thermally-conductive nanofluids. Both size and shape of the prepared NSs ranged from 5 to 1000 nm, and from nanodots (NDs) to spindle nano-aggregates (NAs), respectively. The catalytic activity of these NSs towards the PSCB was followed up by thermogravimetric analysis (TGA), where they increased the percentage of total weight loss, and lowered the decomposition temperatures of PSCB...
January 12, 2017: Nanotechnology
Martina Romio, Camillo La Mesa
Multi-walled carbon nanotubes, MWCNTs, are stabilized thanks to the surface wrapping of single-strand DNA, ss-DNA; the resulting adducts are kinetically and thermodynamically stable Such entities build up nano-hybrids with titania, TiO2, nano-particles, in presence of surfactant as an adjuvant. The conditions leading to TiO2 adsorption onto ss-DNA/CNTs were investigated, by optimizing the concentration of adducts, nano-particles (NPs), and of the cationic surfactant (CTAB). Controlling the working conditions makes possible to get homogeneously organized hybrids...
December 24, 2016: Colloids and Surfaces. B, Biointerfaces
Sreedevi Krishnakumar, Karical R Gopidas
A simple method for covalent functionalization of Fréchet-type dendron nanoparticles (FDN) by tris-bipyridylruthenium(II) is described. Covalent functionalization is achieved by chemically reducing the diazo derivative of a ruthenium(II) bipyridine complex in the presence of FDNs wherein the radical species generated gets covalently linked to the nanoparticle surface. Simplicity, rapidity and robustness are the advantages offered by the present approach. The nanoparticles, post functionalization, were characterized by transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), thermogravimetric analysis (TGA), and IR, UV-visible, and NMR spectroscopic techniques...
January 6, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Wenyan Yin, Jie Yu, Fengting Lv, Liang Yan, Li Rong Zheng, Zhanjun Gu, Yuliang Zhao
We have developed a biocompatible antibacterial system based on polyethylene glycol functionalized molybdenum disulfide nanoflowers (PEG-MoS2 NFs). The PEG-MoS2 NFs have high near-infrared (NIR) absorption and peroxidase-like activity, which can efficiently catalyze decomposition of low concentration of H2O2 to generate hydroxyl radicals (·OH). The conversion of H2O2 into ·OH can avoid the toxicity of high concentration of H2O2 and the ·OH has higher antibacterial activity, making resistant bacteria more vulnerable and wounds more easily cured...
December 27, 2016: ACS Nano
V Kalaparthi, S Palantavida, N E Mordvinova, O I Lebedev, I Sokolov
Here we report on self-assembly of novel multi-hierarchically structured meso(nano)porous colloidal silica particles which have cylindrical pores of 4-6nm, overall size of ∼10μm and "cracks" of 50-200nm. These cracks make particles look like micro-sponges. The particles were prepared through a modified templated sol-gel self-assembly process. The mechanism of assembly of these particles is investigated. Using encapsulated fluorescent dye, we demonstrate that the spongy particles are advantageous to facilitate dye diffusion out of particles...
December 18, 2016: Journal of Colloid and Interface Science
Xiuxia Zuo, Yonggao Xia, Qing Ji, Xiang Gao, Shanshan Yin, Meimei Wang, Xiaoyan Wang, Bao Qiu, Anxiang Wei, Zaicheng Sun, Zhaoping Liu, Jin Zhu, Ya-Jun Cheng
Porous silicon has found wide applications in many different fields including catalysis and lithium-ion batteries. Three-dimensional hierarchical macro-/mesoporous silicon is synthesized from zero-dimensional Stöber silica particles through a facile and scalable magnesiothermic reduction process. By systematic structure characterization of the macro-/mesoporous silicon, a self-templating mechanism governing the formation of the porous silicon is proposed. Applications as lithium-ion battery anode and photocatalytic hydrogen evolution catalyst are demonstrated...
December 28, 2016: ACS Nano
Hang Xu, Xiao-Fang Liu, Chun-Shuai Cao, Bin Zhao, Peng Cheng, Liang-Nian He
Based on a novel ligand 5-(2,6-bis(4-carboxyphenyl)pyridin-4-yl)isophthalic acid (H4BCP) with large skeletons, a unique porous framework {[Cu2(BCP)(H2O)2]·3DMF} n (1) assembled by nano-sized and censer-like [Cu30] cages is successfully obtained and structurally characterized. In 1, the large 1D channel in frameworks and window size in the nanocages can enrich methylene blue and capture CO2, exhibiting the promising applications in environmental protection. More importantly, the explorations on the cycloaddition reaction of CO2 and aziridines with various substituents suggest that 1 can serve as an efficient heterogeneous catalyst for CO2 conversion with aziridines in a solvent-free system, which can be reused at least ten times without any obvious loss in catalytic activity...
November 2016: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
Zhen Zheng, Anming Tang, Yong Guan, Liang Chen, Fuqiang Wang, Peiyao Chen, Weijuan Wang, Yufeng Luo, Yangchao Tian, Gaolin Liang
Alkaline phosphatase (ALP) is an important enzyme, but direct imaging of ALP activity with high spatiotemporal resolution remains challenging. In this work, we rationally designed an iodinated hydrogelator precursor Nap-Phe-Phe(I)-Tyr(H2PO3)-OH (1P) which self-assembles into nanofibers to form hydrogel under the catalysis of ALP. With this property of concentrating iodine atoms at the locations of ALP, 1P was successfully applied for direct nanocomputed tomography (nano-CT) imaging of ALP activity in bacteria for the first time...
December 9, 2016: Analytical Chemistry
Ichiro Yamato, Yoshimi Kakinuma, Takeshi Murata
Among the many types of bioenergy-transducing machineries, F- and V-ATPases are unique bio- and nano-molecular rotary motors. The rotational catalysis of F1-ATPase has been investigated in detail, and molecular mechanisms have been proposed based on the crystal structures of the complex and on extensive single-molecule rotational observations. Recently, we obtained crystal structures of bacterial V1-ATPase (A3B3 and A3B3DF complexes) in the presence and absence of nucleotides. Based on these new structures, we present a novel model for the rotational catalysis mechanism of V1-ATPase, which is different from that of F1-ATPases...
2016: Biophysics and Physicobiology
G Deokar, N S Rajput, P Vancsó, F Ravaux, M Jouiad, D Vignaud, F Cecchet, J-F Colomer
Vertically aligned MoS2 nanosheets (NSs) with exposed edges were successfully synthesized over a large area (∼2 cm(2)). The NSs were grown using an ambient pressure chemical vapor deposition technique via rapid sulfurization of sputter deposited thick molybdenum films. Extensive characterization of the grown MoS2 NSs has been carried out using high resolution scanning and transmission electron microscopy (SEM & TEM). A special care was given to the TEM lamella preparation process by means of a focused ion beam to preserve the NS growth direction...
January 7, 2017: Nanoscale
Jin-Hui Zhong, Xi Jin, Lingyan Meng, Xiang Wang, Hai-Sheng Su, Zhi-Lin Yang, Christopher T Williams, Bin Ren
An atomic- and molecular-level understanding of heterogeneous catalysis is required to characterize the nature of active sites and improve the rational design of catalysts. Achieving this level of characterization requires techniques that can correlate catalytic performances to specific surface structures, so as to avoid averaging effects. Tip-enhanced Raman spectroscopy combines scanning probe microscopy with plasmon-enhanced Raman scattering and provides simultaneous topographical and chemical information at the nano/atomic scale from ambient to ultrahigh-vacuum and electrochemical environments...
November 21, 2016: Nature Nanotechnology
Xin Li, Jiaguo Yu, S Wageh, Ahmed A Al-Ghamdi, Jun Xie
In recent years, heterogeneous photocatalysis has received much research interest because of its powerful potential applications in tackling many important energy and environmental challenges at a global level in an economically sustainable manner. Due to their unique optical, electrical, and physicochemical properties, various 2D graphene nanosheets-supported semiconductor composite photocatalysts have been widely constructed and applied in different photocatalytic fields. In this review, fundamental mechanisms of heterogeneous photocatalysis, including thermodynamic and kinetics requirements, are first systematically summarized...
December 2016: Small
Leonardo Triggiani, Ana B Muñoz-García, Angela Agostiano, Michele Pavone
Strontium titanate (SrTiO3, STO) is a prototypical perovskite oxide, widely exploited in many technological applications, from catalysis to energy conversion devices. In the context of solid-oxide fuel cells, STO has been recently applied as an epitaxial substrate for nano-sized layers of mixed ion-electron conductive catalysts with enhanced electrochemical performances. To extend the applications of such heterogeneous nano-cathodes in real devices, also the STO support should be active for both electron transport and oxide diffusion...
October 11, 2016: Physical Chemistry Chemical Physics: PCCP
Gonzalo Prieto, Harun Tüysüz, Nicolas Duyckaerts, Johannes Knossalla, Guang-Hui Wang, Ferdi Schüth
Catalysis is at the core of almost every established and emerging chemical process and also plays a central role in the quest for novel technologies for the sustainable production and conversion of energy. Particularly since the early 2000s, a great surge of interest exists in the design and application of micro- and nanometer-sized materials with hollow interiors as solid catalysts. This review provides an updated and critical survey of the ever-expanding material architectures and applications of hollow structures in all branches of catalysis, including bio-, electro-, and photocatalysis...
November 23, 2016: Chemical Reviews
Xiaofang Zhang, Wenjing Lin, Liyang Wen, Na Yao, Shuyu Nie, Lijuan Zhang
Unimolecular polymeric micelles have several features, such as thermodynamic stability, small particle size, biocompatibility, and the ability to internalize hydrophobic molecules. These micelles have recently attracted significant attention in various applications, such as nano-reactors, catalysis, and drug delivery. However, few attempts have explored the formation mechanisms and conditions of unimolecular micelles due to limited experimental techniques. In this study, a unimolecular micelle system formed from β-cyclodextrin-graft-{poly(lactide)-block-poly(2-(dimethylamino) ethyl multimethacrylate)-block-poly[oligo (2-ethyl-2-oxazoline) methacrylate]} β-CD-g-(PLA-b-PDMAEMA-b-PEtOxMA) star-like block copolymers in aqueous media was investigated by dissipative particle dynamics (DPD) to explore the formation process of unimolecular micelles...
September 29, 2016: Physical Chemistry Chemical Physics: PCCP
Xing Ma, Ana C Hortelão, Tania Patiño, Samuel Sánchez
Enzymes play a crucial role in many biological processes which require harnessing and converting free chemical energy into kinetic forces in order to accomplish tasks. Enzymes are considered to be molecular machines, not only because of their capability of energy conversion in biological systems but also because enzymatic catalysis can result in enhanced diffusion of enzymes at a molecular level. Enlightened by nature's design of biological machinery, researchers have investigated various types of synthetic micro/nanomachines by using enzymatic reactions to achieve self-propulsion of micro/nanoarchitectures...
October 25, 2016: ACS Nano
Galina Marzun, Alexander Levish, Viktor Mackert, Tanja Kallio, Stephan Barcikowski, Philipp Wagener
Platinum and iridium are rare and expensive noble metals that are used as catalysts for different sectors including in heterogeneous chemical automotive emission catalysis and electrochemical energy conversion. Nickel and its alloys are promising materials to substitute noble metals. Nickel based materials are cost-effective with good availability and show comparable catalytic performances. The nickel-molybdenum system is a very interesting alternative to platinum in water electrolysis. We produced ligand-free nickel-molybdenum nanoparticles by laser ablation in water and acetone...
March 1, 2017: Journal of Colloid and Interface Science
Sara Blomberg, Jianfeng Zhou, Johan Gustafson, Johan Zetterberg, Edvin Lundgren
In recent years, efforts have been made in catalysis related surface science studies to explore the possibilities to perform experiments at conditions closer to those of a technical catalyst, in particular at increased pressures. Techniques such as high pressure scanning tunneling/atomic force microscopy (HPSTM/AFM), near ambient pressure x-ray photoemission spectroscopy (NAPXPS), surface x-ray diffraction (SXRD) and polarization-modulation infrared reflection absorption spectroscopy (PM-IRAS) at semi-realistic conditions have been used to study the surface structure of model catalysts under reaction conditions, combined with simultaneous mass spectrometry (MS)...
November 16, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
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