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Atomic force microscopy

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https://www.readbyqxmd.com/read/29331777/comparing-the-antifouling-effects-of-activated-carbon-and-tio2-in-ultrafiltration-membrane-development
#1
Qianyu Liu, Shaobin Huang, Yongqing Zhang, Shuaifei Zhao
We use activated carbon (AC) and titanium oxide (TiO2) nanomaterials as the additives to prepare four polyvinylidene fluoride (PVDF) based ultrafiltration membranes by nonsolvent induced phase separation. The surface properties (pore size, porosity, hydrophilicity and roughness) of the membranes are characterized by scanning electron microscopy, water contact angle measurement, and atomic force microscopy. The chemical properties of the membranes are evaluated by Fourier transform infrared spectroscopy with attenuated total reflection and X-ray diffraction...
January 6, 2018: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/29330363/disulfide-isomerization-reactions-in-titin-immunoglobulin%C3%A2-domains-enable-a-mode-of-protein-elasticity
#2
David Giganti, Kevin Yan, Carmen L Badilla, Julio M Fernandez, Jorge Alegre-Cebollada
The response of titin to mechanical forces is a major determinant of the function of the heart. When placed under a pulling force, the unstructured regions of titin uncoil while its immunoglobulin (Ig) domains unfold and extend. Using single-molecule atomic force microscopy, we show that disulfide isomerization reactions within Ig domains enable a third mechanism of titin elasticity. Oxidation of Ig domains leads to non-canonical disulfide bonds that stiffen titin while enabling force-triggered isomerization reactions to more extended states of the domains...
January 12, 2018: Nature Communications
https://www.readbyqxmd.com/read/29329077/nano-hydroxyapatite-blasted-titanium-surface-creates-a-biointerface-able-to-govern-src-dependent-osteoblast-metabolism-as-prerequisite-to-ecm-remodeling
#3
Célio J C Fernandes, Fábio Bezerra, Marcel R Ferreira, Amanda F C Andrade, Thais Silva Pinto, Willian F Zambuzzi
Over the last several years, we have focused on the importance of intracellular signaling pathways in dynamically governing the biointerface between pre-osteoblast and surface of biomaterial. Thus, this study investigates the molecular hallmarks involved in the pre-osteoblast relationship with different topography considering Machined (Mc), Dual Acid-Etching (DAE), and nano hydroxyapatite-blasted (nHA) groups. There was substantial differences in topography of titanium surface, considering Atomic Force Microscopy and water contact angle (Mc = 81...
December 28, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/29328941/production-of-mono-to-few-layer-mos2-nanosheets-in-isopropanol-by-a-salt-assisted-direct-liquid-phase-exfoliation-method
#4
Huaizhi Liu, Liao Xu, Weixu Liu, Bo Zhou, Yinyan Zhu, Lihua Zhu, Xiaoqing Jiang
Here, we report a facile salt-assisted direct liquid-phase exfoliation method for mass production of MoS2 nanosheets. We choose organic solvent isopropanol (IPA) as exfoliation media and potassium ferrocyanide, potassium sodium tartrate, or sodium tartrate as salt, the assistant. The selected salts show universal and efficient assistant effect for the exfoliation of MoS2 in IPA. Especially, potassium ferrocyanide (K4Fe(CN)6) can enhance the exfoliation efficiency up to 73 times and a dispersion of MoS2 nanosheets with concentration as high as 0...
January 6, 2018: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/29328122/model-assisted-measuring-method-for-periodical-sub-wavelength-nanostructures
#5
Gabriela Alexe, Andreas Tausendfreund, Dirk Stöbener, Andreas Fischer
This paper describes a scatterometry approach designed by simulations for the in-line characterization of sub-wavelength sinusoidal gratings, which are formed on a transparent foil in a roll-to-roll procedure. Currently used methods are based on series of in situ measurements of the specular optical response at different incident angles or wavelengths for acquiring dimensional information on the gratings. The capability of single measurements of the first diffraction maxima at a fixed incident angle and wavelength to accurately measure the height of the sub-wavelength sinusoidal gratings is investigated in this work...
January 1, 2018: Applied Optics
https://www.readbyqxmd.com/read/29327927/atom-dependent-edge-enhanced-second-harmonic-generation-on-mos2-monolayers
#6
Kuang-I Lin, Yen-Hung Ho, Shu-Bai Liu, Jian-Jhih Ciou, Bo-Ting Huang, Christopher Chen, Han-Ching Chang, Chien-Liang Tu, Chang-Hsiao Chen
Edge morphology and lattice orientation of single-crystal molybdenum disulfide (MoS2) monolayers, a transition metal dichalcogenide (TMD), possessing a triangular shape with different edges grown by chemical vapor deposition are characterized by atomic force microscopy and transmission electron microscopy. Multiphoton laser scanning microscopy is utilized to study one-dimensional atomic edges of MoS2 monolayers with localized mid-gap electronic states, which result in greatly enhanced optical second-harmonic generation (SHG)...
January 12, 2018: Nano Letters
https://www.readbyqxmd.com/read/29327915/multispectral-atomic-force-microscopy-infrared-nano-imaging-of-malaria-infected-red-blood-cells
#7
David Perez-Guaita, Kamila Kochan, Mitchell Batty, Christian Doerig, Jose Garcia-Bustos, Shirley Josefina Espinoza Herrera, Don McNaughton, Philip Heraud, Bayden R Wood
Atomic Force Microscopy-Infrared (AFM-IR) spectroscopy is a powerful new technique that can be applied to study molecular composition of cells and tissues at the nano-scale. AFM-IR maps are acquired using single wavenumber value: they show either the absorbance plotted against a single wavenumber value, or a ratio of two absorbance values. Here we implement multivariate image analysis to generate multivariate AFM-IR maps, and use this approach to resolve subcellular structural information in red blood cells infected with Plasmodium falciparum at different stages of development...
January 12, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29327092/mesoporous-nickel-oxide-nio-nanopetals-for-ultrasensitive-glucose-sensing
#8
Suryakant Mishra, Priyanka Yogi, P R Sagdeo, Rajesh Kumar
Glucose sensing properties of mesoporous well-aligned, dense nickel oxide (NiO) nanostructures (NSs) in nanopetals (NPs) shape grown hydrothermally on the FTO-coated glass substrate has been demonstrated. The structural study based investigations of NiO-NPs has been carried out by X-ray diffraction (XRD), electron and atomic force microscopies, energy dispersive X-ray (EDX), and X-ray photospectroscopy (XPS). Brunauer-Emmett-Teller (BET) measurements, employed for surface analysis, suggest NiO's suitability for surface activity based glucose sensing applications...
January 11, 2018: Nanoscale Research Letters
https://www.readbyqxmd.com/read/29327023/a-step-towards-understanding-the-beneficial-influence-of-a-lipon-based-artificial-sei-on-silicon-thin-film-anodes-in-lithium-ion-batteries
#9
A Reyes Jiménez, R Nölle, R Wagner, J Hüsker, M Kolek, R Schmuch, M Winter, T Placke
In this work, we present a comprehensive study on the influence of lithium phosphorus oxynitride (LIPON) as a possible "artificial SEI layer" on the electrochemical performance of pure silicon (Si) thin film electrodes for a possible application in microbatteries or on-chip batteries. Si thin film anodes (140 nm) with and without an additional amorphous LIPON surface layer of different thicknesses (100-300 nm) were prepared by magnetron sputter deposition. The LIPON surface coating was characterized thoroughly by means of electrochemical impedance spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy...
January 12, 2018: Nanoscale
https://www.readbyqxmd.com/read/29327016/isoenergic-modification-of-whey-protein-structure-by-denaturation-and-crosslinking-using-transglutaminase
#10
Emil G P Stender, Glykeria Koutina, Kristoffer Almdal, Tue Hassenkam, Alan Mackie, Richard Ipsen, Birte Svensson
Transglutaminase (TG) catalyzes formation of covalent bonds between lysine and glutamine side chains and has applications in manipulation of food structure. Physical properties of a whey protein mixture (SPC) denatured either at elevated pH or by heat-treatment and followed by TG catalyzed crosslinking, have been characterised using dynamic light scattering, size exclusion chromatography, flourescence spectroscopy and atomic force microscopy. The degree of enzymatic crosslinking appeared higher for pH- than for heat-denatured SPC...
January 12, 2018: Food & Function
https://www.readbyqxmd.com/read/29327012/low-force-spectroscopy-on-graphene-membranes-by-scanning-tunneling-microscopy
#11
Bernd Uder, Haibin Gao, Peter Kunnas, Niels de Jonge, Uwe Hartmann
Two-dimensional atomically flat sheets with a high mechanical flexibility are very attractive as ultrathin membranes but are also inherently challenging for microscopic investigations. We report on a method using Scanning Tunneling Microscopy (STM) under ultra-high vacuum conditions for non-indenting low-force spectroscopy on micrometer-sized freestanding graphene membranes. The method is based on applying quasi-static voltage ramps with active feedback at low tunneling currents and ultimately relies on the attractive electrostatic force between the tip and the membrane...
January 12, 2018: Nanoscale
https://www.readbyqxmd.com/read/29327003/carbon-dots-as-absorbance-promoter-probes-for-detection-of-cu-ii-ions-in-aqueous-solution-central-composite-design-approach
#12
S A R Shahamirifard, M Ghaedi, M Montazerozohori, A Masoudiasl
In this work, the use of carbon dots (CDs) as a complexing agent and sensitizer in a polymeric matrix for determination of copper(ii) by UV-vis spectroscopy is reported for the first time. A new and highly selective Schiff base, namely, (N',N'''E,N',N'''E)-N',N'''-((((2-hydroxypropane-1,3-diyl)bis(oxy))bis(2,1-phenylene))bis(methan-ylylidene))di(isonicotinohydrazide) (NHBMDI), was also incorporated in the polymeric matrix. For the first time, the membrane composition of the proposed optical sensor including NHBMDI as the ionophore, tetraphenylborate (NaTPB) as the anionic additive, dibutyl phthalate (DBP) as the plasticizer and polyvinyl chloride (PVC) as the immobilizer was optimized through central composite design combined with the desirability function approach (DFA) because this method saves material and time consumption and is therefore cost effective...
January 12, 2018: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/29324715/nitrogen-doped-diamond-film-for-optical-investigation-of-hemoglobin-concentration
#13
Daria Majchrowicz, Monika Kosowska, Kamatchi J Sankaran, Przemysław Struk, Michał Wąsowicz, Michał Sobaszek, Ken Haenen, Małgorzata Jędrzejewska-Szczerska
In this work we present the fabrication and characterization of a diamond film which can be utilized in the construction of optical sensors for the investigation of biological samples. We produced a nitrogen-doped diamond (NDD) film using a microwave plasma enhanced chemical vapor deposition (MWPECVD) system. The NDD film was investigated with the use of scanning electron microscopy (SEM), atomic force microscopy (AFM) and Raman spectroscopy. The NDD film was used in the construction of the fiber optic sensor...
January 11, 2018: Materials
https://www.readbyqxmd.com/read/29323877/curcumin-conjugated-gold-clusters-for-bioimaging-and-anticancer-applications
#14
Saravanan Govindaraju, Arunkumar Rengaraj, Roshini Arivazhagan, Yun-Suk Huh, Kyusik Yun
Curcumin-conjugated gold clusters (CUR-AuNCs) were synthesized using a "green" procedure and utilized as an anticancer and a bioimaging agent. Curcumin is a well-known anticancer agent, which forms a cluster when reacting with a gold precursor under mild alkali condition. A fluorescence spectroscopy analysis showed that the CUR-AuNCs emitted red fluorescence (650 nm) upon visible light (550) irradiation. Fourier transform infrared spectroscopy analysis confirmed the stretching and bending nature between the gold atoms and curcumin...
January 11, 2018: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/29322765/influence-of-non-stoichiometry-on-proton-conductivity-in-thin-film-yttrium-doped-barium-zirconate
#15
Jilai Ding, Janakiraman Balachandran, Xiahan Sang, Wei Guo, Gabriel M Veith, Craig A Bridges, Christopher M Rouleau, Jonathan David Poplawsky, Nazanin Bassiri-Gharb, Panchapakesan Ganesh, Raymond R Unocic
Proton conducting perovskites have been widely studied due to their potential application as solid electrolytes in intermediate temperature solid oxide fuel cells. Structural and chemical heterogeneities can develop during synthesis, device fabrication or service, which can profoundly affect proton transport. Here, we use time-resolved Kelvin probe force microscopy, scanning transmission electron microscopy, atom probe tomography and density functional theory calculations to intentionally introduce Ba-deficient planar and spherical defects, and link the resultant atomic structure with proton transport behavior in both stoichiometric and non-stoichiometric epitaxial, yttrium doped barium zirconate thin films...
January 11, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29322154/polyelectrolyte-multilayers-under-compression-concurrent-osmotic-stress-and-colloidal-probe-atomic-force-microscopy
#16
Bo Wu, Guangming Liu, Guangzhao Zhang, Vincent S J Craig
Colloidal interactions have been characterised using both osmotic stress and surface forces. Here these methods are employed concurrently to measure the interaction forces of polyelectrolyte multilayers that when cross-linked form a dextran impermeable membrane. The force data, corrected for the thickness of the polyelectrolyte multilayer film, has been expressed as pressure versus separation enabling the interaction from osmotic stress measurements to be compared to the measured interaction from the colloid probe technique...
January 11, 2018: Soft Matter
https://www.readbyqxmd.com/read/29320686/dynamic-model-for-characterizing-contractile-behaviors-and-mechanical-properties-of-a-cardiomyocyte
#17
Chuang Zhang, Wenxue Wang, Wenhui He, Ning Xi, Yuechao Wang, Lianqing Liu
Studies on the contractile dynamics of heart cells have attracted broad attention for the development of both heart disease therapies and cardiomyocyte-actuated micro-robotics. In this study, a linear dynamic model of a single cardiomyocyte cell was proposed at the subcellular scale to characterize the contractile behaviors of heart cells, with system parameters representing the mechanical properties of the subcellular components of living cardiomyocytes. The system parameters of the dynamic model were identified with the cellular beating pattern measured by a scanning ion conductance microscope...
January 9, 2018: Biophysical Journal
https://www.readbyqxmd.com/read/29320677/warhammers-for-peaceful-times
#18
Piotr E Marszalek
The Perkins group has recently developed a number of improved atomic force microscopy cantilevers using the focused ion beam technology. They compared the performance of these cantilevers in "real-life" biophysical single-molecule force spectroscopy measurements on protein unfolding, and the results of this comparison are reported in this issue of Biophysical Journal.
January 9, 2018: Biophysical Journal
https://www.readbyqxmd.com/read/29320535/rhombic-organization-of-microvilli-domains-found-in-a-cell-model-of-the-human-intestine
#19
Jonas Franz, Jonas Grünebaum, Marcus Schäfer, Dennis Mulac, Florian Rehfeldt, Klaus Langer, Armin Kramer, Christoph Riethmüller
Symmetry is rarely found on cellular surfaces. An exception is the brush border of microvilli, which are essential for the proper function of transport epithelia. In a healthy intestine, they appear densely packed as a 2D-hexagonal lattice. For in vitro testing of intestinal transport the cell line Caco-2 has been established. As reported by electron microscopy, their microvilli arrange primarily in clusters developing secondly into a 2D-hexagonal lattice. Here, atomic force microscopy (AFM) was employed under aqueous buffer conditions on Caco-2 cells, which were cultivated on permeable filter membranes for optimum differentiation...
2018: PloS One
https://www.readbyqxmd.com/read/29320462/unsaturated-fatty-acids-affect-quorum-sensing-communication-system-and-inhibit-motility-and-biofilm-formation-of-acinetobacter-baumannii
#20
Marion Nicol, Stéphane Alexandre, Jean-Baptiste Luizet, Malena Skogman, Thierry Jouenne, Suzana P Salcedo, Emmanuelle Dé
The increasing threat of Acinetobacter baumannii as a nosocomial pathogen is mainly due to the occurrence of multidrug-resistant strains that are associated with the real problem of its eradication from hospital wards. The particular ability of this pathogen to form biofilms contributes to its persistence, increases antibiotic resistance, and promotes persistent/device-related infections. We previously demonstrated that virstatin, which is a small organic compound known to decrease virulence of Vibrio cholera via an inhibition of T4-pili expression, displayed very promising activity to prevent A...
January 10, 2018: International Journal of Molecular Sciences
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