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Atomic force microscopy

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https://www.readbyqxmd.com/read/28346826/imaging-successive-intermediate-states-of-the-on-surface-ullmann-reaction-on-cu-111-role-of-the-metal-coordination
#1
Sören Zint, Daniel Ebeling, Tobias Schlöder, Sebastian Ahles, Doreen Mollenhauer, Hermann A Wegner, Andre Schirmeisen
The in-depth knowledge about on-surface reaction mechanisms is crucial for the tailor-made design of covalently bonded organic frameworks, for applications such as nanoelectronic or -optical devices. Latest developments in atomic force microscopy, which rely on functionalizing the tip with single CO molecules at low temperatures allow to image molecular systems with submolecular resolution. Here, we are using this technique to study the complete reaction pathway of the on-surface Ullmann-type coupling between bromotriphenylene molecules on a Cu(111) surface...
March 27, 2017: ACS Nano
https://www.readbyqxmd.com/read/28346217/the-possibility-of-multi-layer-nanofabrication-via-atomic-force-microscope-based-pulse-electrochemical-nanopatterning
#2
Uksu Kim, Noboru Morita, Deug Lee, Martin Jun, Jeong Woo Park
Pulse electrochemical nanopatterning (PECN), a non-contact scanning probe lithography (NC-SPL) process using ultrashort voltage pulses, is based primarily on an electrochemical machining (ECM) process using localized electrochemical oxidation between a sharp tool tip and the sample surface. In this study, nanoscale oxide patterns were formed on silicon Si (100) wafer surfaces via electrochemical surface nanopatterning, by supplying external pulsed currents through non-contact atomic force microscopy. Nanoscale oxide width and height were controlled by modulating the applied pulse duration...
March 27, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28345857/self-cleaning-membranes-from-comb-shaped-copolymers-with-photoresponsive-side-groups
#3
Papatya Kaner, Xiaoran Hu, Samuel W Thomas, Ayse Asatekin
In this study, we present a novel self-cleaning, photoresponsive membrane that is capable of removing pre-deposited foulant layers upon changes in surface morphology in response to UV or visible light irradiation while maintaining stable pore size and water permeance. These membranes were prepared by creating thin film composite (TFC) membranes by coating a porous support membrane with a thin layer of novel comb-shaped graft copolymers at two side-chain lengths featuring polyacrylonitrile (PAN) backbones and photoreactive side-chains, synthesized by atom transfer radical polymerization (ATRP)...
March 27, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28345851/high-resolution-adhesion-mapping-of-the-odd-even-effect-on-a-layer-by-layer-coated-biomaterial-by-atomic-force-microscopy
#4
Kirstin Casdorff, Tobias Keplinger, Herve Bellanger, Benjamin Michen, Silke Sch N, Ingo Burgert
The adhesion behavior of polyelectrolyte multilayers consisting of poly-(diallyldimethylammonium chloride), PDDA, and poly(styrene sulfonate), PSS, towards a silicon AFM tip was studied during their build-up on wood, a chemically heterogeneous, micrometer rough biomaterial and compared with a nanometer rough substrate, namely quartz. The Atomic Force Microscopy based force mapping approach generated high resolution topography-, and adhesion maps within the first bilayers, which point toward a homogeneous layer-by-layer build-up on the biomaterial surface, and therefore indicate an even charge distribution...
March 27, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28342752/chitosan-doped-hybrid-tio2-nanocomposite-based-sol-gel-coating-for-the-corrosion-resistance-of-aluminum-metal-in-3-5-nacl-medium
#5
Balaji J, Sethuraman M G
The study outlines the role of chitosan, a biopolymer on corrosion behavior of Hy/nano-TiO2 based sol-gel coating over aluminum metal. In this study organic-inorganic hybrid sols were synthesized through hydrolysis and condensation of 3-glycidoxypropyltrimethoxy silane (GPTMS), tetraethoxysilane (TEOS) and titanium (IV) isopropoxide (TIP) in acidic solution. Chitosan was doped into sol-gel matrix and self-assembled over aluminum substrate. The resultant chitosan-doped-Hy/nano-TiO2 sol-gel coating was characterized by Fourier Transform Infrared (FT-IR) spectra, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Energy-Dispersive X-ray Spectroscopy (EDX) analyses...
March 22, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28342370/fabrication-and-tribological-properties-of-nanogrids-on-cvd-grown-graphene
#6
Yan Jiang, Yu Sun, Juan Song
We have used atomic force microscopy (AFM) combined with an external sourcemeter to make patterns on CVD-grown graphene, and regular nanogrids have been fabricated on graphene by AFM tip-induced local oxidation. The friction and adhesion properties of graphene with the nanogrids have been characterized by the lateral mode of AFM and the results show that the friction force on the borders of nanogrid is higher than that on the normal area of graphene, yet the adhesion force on the nanogrids decrease slightly due to the change of surface roughness...
March 12, 2017: Micron: the International Research and Review Journal for Microscopy
https://www.readbyqxmd.com/read/28341156/long-range-interactions-between-protein-coated-particles-and-poegma-brush-layers-in-a-serum-environment
#7
Zhaohui Wang, Yafei Luan, Tiansheng Gan, Xiangjun Gong, Hong Chen, To Ngai
Hydrophilic poly[oligo(ethylene glycol) methyl methacrylate] (POEGMA) brush layers with different thickness and graft densities were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) to construct a model surface to examine protein-surface interactions in a serum environment. The thickness of the POEGMA brush layers could be well controlled by the polymerization time and density of the immobilized initiators. The interactions between these brush-modified surfaces and the protein-coated polystyrene (PS) particles in newborn calf serum (NBCS) environment were then measured by total internal reflection microscopy (TIRM)...
February 1, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28340793/a-novel-quartz-crystal-microbalance-sensor-array-based-on-molecular-imprinted-polymers-for-simultaneous-detection-of-clenbuterol-and-its-metabolites
#8
Fan Feng, Jianwu Zheng, Peng Qin, Tao Han, Dayun Zhao
For the rapid and robust detection of both parent clenbuterol (CLB) and its metabolites in swine urine samples, a novel quartz crystal microbalance (QCM) sensor array for CLB detection based on molecularly imprinted polymers (MIPs) was developed in this investigation. At first, clenbuterol and the structural analogs of its metabolites, 4-Aminohippuric acid (AHA) and 4-hydroxymandelic acid (HMA), were chosen as molecular templates. Through computational molecular modeling, the optimum ratio between the functional monomer and molecular template was selected...
May 15, 2017: Talanta
https://www.readbyqxmd.com/read/28340521/stable-and-controllable-synthesis-of-silver-nanowires-for-transparent-conducting-film
#9
Bitao Liu, Hengqing Yan, Shanyong Chen, Youwei Guan, Guoguo Wu, Rong Jin, Lu Li
Silver nanowires without particles are synthesized by a solvothermal method at temperature 150 °C. Silver nanowires are prepared via a reducing agent of glycerol and a capping agent of polyvinylpyrrolidone (M w  ≈ 1,300,000). Both of them can improve the purity of the as-prepared silver nanowires. With controllable shapes and sizes, silver nanowires are grown continuously up to 10-20 μm in length with 40-50 nm in diameter. To improve the yield of silver nanowires, the different concentrations of AgNO3 synthesis silver nanowires are discussed...
December 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28340417/interfacial-interactions-between-skeletonema-costatum-extracellular-organic-matter-and-metal-oxides-implications-for-ceramic-membrane-filtration
#10
Noor Zaouri, Leonardo Gutierrez, Laure Dramas, Daniel Garces, Jean-Philippe Croue
In the current study, the interfacial interactions between the high molecular weight (HMW) compounds of Skeletonema costatum (SKC) extracellular organic matter (EOM) and ZrO2 or Al2O3, were investigated by atomic force microscopy (AFM). HMW SKC-EOM was rigorously characterized and described as a hydrophilic organic compound mainly comprised of polysaccharide-like structures. Lipids and proteins were also observed, although in lower abundance. HMW SKC-EOM displayed attractive forces during approaching (i.e., leading to jump-to-contact events) and adhesion forces during retracting regime to both metal oxides at all solution conditions tested, where electrostatics and hydrogen bonding were suggested as dominant interacting mechanisms...
March 21, 2017: Water Research
https://www.readbyqxmd.com/read/28338927/the-effect-of-aluminum-ion-on-the-aggregation-of-human-islet-amyloid-polypeptide-11-28
#11
Lanlan Su, Cheng Lu, Peng Yan, Nan Zhang, Sheng Cai, Gongjun Zhang, Xingfei Zhou, Bin Li
Metal ions play a critical role in human islet amyloid polypeptide (hIAPP) aggregation, which is believed to be closely associated with β-cell death in type II diabetes. In this work, the effect of Al3+ on the aggregation of hIAPP (11-28) was studied by several different experimental approaches. Atomic force microscopy measurements showed that Al3+ could remarkably inhibit hIAPP(11-28) fibrillogenesis, while Zn2+ had a slight promotion effect on peptide aggregation, which was also confirmed by Thioflavin T fluorescence observation...
March 10, 2017: Acta Biochimica et Biophysica Sinica
https://www.readbyqxmd.com/read/28338691/surfactant-free-single-layer-graphene-in-water
#12
George Bepete, Eric Anglaret, Luca Ortolani, Vittorio Morandi, Kai Huang, Alain Pénicaud, Carlos Drummond
Dispersing graphite in water to obtain true (single-layer) graphene in bulk quantity in a liquid has been an unreachable goal for materials scientists in the past decade. Similarly, a diagnostic tool to identify solubilized graphene in situ has been long awaited. Here we show that homogeneous stable dispersions of single-layer graphene (SLG) in water can be obtained by mixing graphenide (negatively charged graphene) solutions in tetrahydrofuran with degassed water and evaporating the organic solvent. In situ Raman spectroscopy of these aqueous dispersions shows all the expected characteristics of SLG...
April 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28336865/synthesis-optical-and-structural-properties-of-copper-sulfide-nanocrystals-from-single-molecule-precursors
#13
Peter A Ajibade, Nandipha L Botha
We report the synthesis and structural studies of copper sulfide nanocrystals from copper (II) dithiocarbamate single molecule precursors. The precursors were thermolysed in hexadecylamine (HDA) to prepare HDA-capped CuS nanocrystals. The optical properties of the nanocrystals studied using UV-visible and photoluminescence spectroscopy showed absorption band edges at 287 nm that are blue shifted, and the photoluminescence spectra show emission curves that are red-shifted with respect to the absorption band edges...
February 4, 2017: Nanomaterials
https://www.readbyqxmd.com/read/28336849/modification-of-the-surface-topography-and-composition-of-ultrafine-and-coarse-grained-titanium-by-chemical-etching
#14
Denis V Nazarov, Elena G Zemtsova, Alexandr Yu Solokhin, Ruslan Z Valiev, Vladimir M Smirnov
In this study, we present the detailed investigation of the influence of the etching medium (acidic or basic Piranha solutions) and the etching time on the morphology and surface relief of ultrafine grained (UFG) and coarse grained (CG) titanium. The surface relief and morphology have been studied by means of scanning electron microscopy (SEM), atomic force microscopy (AFM), and the spectral ellipsometry. The composition of the samples has been determined by X-ray fluorescence analysis (XRF) and X-ray Photoelectron Spectroscopy (XPS)...
January 13, 2017: Nanomaterials
https://www.readbyqxmd.com/read/28336846/preparation-of-g-c%C3%A2-n%C3%A2-graphene-composite-for-detecting-no%C3%A2-at-room-temperature
#15
Shaolin Zhang, Nguyen Thuy Hang, Zhijun Zhang, Hongyan Yue, Woochul Yang
Graphitic carbon nitride (g-C₃N₄) nanosheets were exfoliated from bulk g-C₃N₄ and utilized to improve the sensing performance of a pure graphene sensor for the first time. The role of hydrochloric acid treatment on the exfoliation result was carefully examined. The exfoliated products were characterized by X-ray diffraction (XRD) patterns, scanning electron microscopy (SEM), atomic force microscopy (AFM), and UV-Vis spectroscopy. The exfoliated g-C₃N₄ nanosheets exhibited a uniform thickness of about 3-5 nm and a lateral size of about 1-2 µm...
January 12, 2017: Nanomaterials
https://www.readbyqxmd.com/read/28335591/heteroatom-doped-perihexacene-from-a-double-helicene-precursor-on-surface-synthesis-and-properties
#16
Xiao-Ye Wang, Thomas Dienel, Marco Di Giovannantonio, Gabriela Borin Barin, Neerav Kharche, Okan Deniz, José I Urgel, Roland Widmer, Samuel Stolz, Luis Henrique De Lima, Matthias Muntwiler, Matteo Tommasini, Vincent Meunier, Pascal Ruffieux, Xinliang Feng, Roman Fasel, Klaus Müllen, Akimitsu Narita
We report on the surface-assisted synthesis and spectroscopic characterization of the hitherto longest periacene analogue with oxygen-boron-oxygen (OBO) segments along the zigzag edges, that is, a heteroatom-doped perihexacene 1. Surface-catalyzed cyclodehydrogenation successfully transformed the double helicene precursor 2, i.e., 12a,26a-dibora-12,13,26,27-tetraoxa-benzo[1,2,3-hi:4,5,6-h'i']dihexacene, into the planar perihexacene analogue 1, which was visualized by scanning tunneling microscopy and noncontact atomic force microscopy...
March 27, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28335337/effect-of-crystal-orientation-on-self-assembly-nanocones-formed-on-tungsten-surface-induced-by-helium-ion-irradiation-and-annealing
#17
Shilin Huang, Guang Ran, Penghui Lei, Shenghua Wu, Nanjun Chen, Ning Li
The self-assembly nanocone structures on the surface of polycrystalline tungsten were created by He⁺ ion irradiation and then annealing, and the resulting topography and morphology were characterized using atomic force microscopy and scanning electron microscopy. The cross-sectional samples of the self-assembly nanocones were prepared using an in situ-focused ion beam and then observed using transmission electron microscopy. The self-assembly nanocones were induced by the combined effect of He⁺ ion irradiation, the annealing process and the chromium impurity...
November 12, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28335334/hybrid-nanostructures-containing-sulfadiazine-modified-chitosan-as-antimicrobial-drug-carriers
#18
Bogdanel Silvestru Munteanu, Raluca Petronela Dumitriu, Lenuta Profire, Liviu Sacarescu, Gabriela Elena Hitruc, Elena Stoleru, Marius Dobromir, Ana Lavinia Matricala, Cornelia Vasile
Chitosan (CH) nanofibrous structures containing sulfadiazine (SDZ) or sulfadiazine modified chitosan (SCH) in the form of functional nanoparticles attached to nanofibers (hybrid nanostructures) were obtained by mono-axial and coaxial electrospinning. The mono-axial design consisted of a SDZ/CH mixture solution fed through a single nozzle while the coaxial design consisted of SCH and CH solutions separately supplied to the inner and outer nozzle (or in reverse order). The CH ability to form nanofibers assured the formation of a nanofiber mesh, while SDZ and SCH, both in form of suspensions in the electrospun solution, assured the formation of active nanoparticles which remained attached to the CH nanofiber mesh after the electrospinning process...
November 10, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28335332/micromechanical-properties-of-nanostructured-clay-oxide-multilayers-synthesized-by-layer-by-layer-self-assembly
#19
Dongwei Hou, Guoping Zhang, Rohit Raj Pant, Zhongxin Wei, Shuilong Shen
Clay-based nanostructured multilayers, such as clay-polymer multilayers and clay-oxide multilayers, have attracted growing attention owing to their remarkable mechanical properties and promising application in various fields. In this paper, synthesis of a new kind of nanostructured clay-oxide multilayers by layer-by-layer self-assembly was explored. Nano-mechanical characterization of 18 clay-based multilayer samples, prepared under as-deposited (i.e., air-dried) and annealing conditions at 400 °C/600 °C with different precursor cations and multilayer structure, were carried out using nanoindentation testing, atomic force microscopy (AFM), and X-ray diffraction (XRD)...
November 8, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28335324/dna-origami-reorganizes-upon-interaction-with-graphite-implications-for-high-resolution-dna-directed-protein-patterning
#20
Masudur Rahman, David Neff, Nathaniel Green, Michael L Norton
Although there is a long history of the study of the interaction of DNA with carbon surfaces, limited information exists regarding the interaction of complex DNA-based nanostructures with the important material graphite, which is closely related to graphene. In view of the capacity of DNA to direct the assembly of proteins and optical and electronic nanoparticles, the potential for combining DNA-based materials with graphite, which is an ultra-flat, conductive carbon substrate, requires evaluation. A series of imaging studies utilizing Atomic Force Microscopy has been applied in order to provide a unified picture of this important interaction of structured DNA and graphite...
October 31, 2016: Nanomaterials
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