Cell adhesion molecules (CAMs) mediate cell attachment and stress
transfer through extracellular domains. Here we forcibly unfold the Ig
domains of a prototypical Ig superfamily CAM that contains ...intradomain
disulfide bonds. The Ig domains of all such CAMs have conformations
homologous to cadherin extracellular domains, titin Ig-type domains,
and fibronectin type-III (FNIII) domains. Atomic force microscopy has
been used to extend the five Ig domains of Mel-CAM (melanoma CAM)—a
protein that is overexpressed in metastatic melanomas—under conditions
where the disulfide bonds were either left intact or disrupted through
reduction. Under physiological conditions where intradomain disulfide
bonds are intact, partial unfolding was observed at forces far smaller
than those reported previously for either titin's Ig-type domains or
tenascin's FNIII domains. This partial unfolding under low force may
be an important mechanism for imparting elasticity to cell–cell
contacts, as well as a regulatory mechanism for adhesive interactions.
Under reducing conditions, Mel-CAM's Ig domains were found to fully
unfold through a partially folded state and at slightly higher forces.
The results suggest that, in divergent evolution of all such domains,
stabilization imparted by disulfide bonds relaxes requirements for
strong, noncovalent, folded-state interactions.
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State of the art three-dimensional atomic force microscopes (3D-AFM) cannot measure three spatial dimensions separately from each other. A 3D-AFM-head with true 3D-probing capabilities is presented ...in this paper. It detects the so-called 3D-Nanoprobes CD-tip displacement with a differential interferometer and an optical lever. The 3D-Nanoprobe was specifically developed for tactile 3D-probing and is applied for critical dimension (CD) measurements. A calibrated 3D-Nanoprobe shows a selectivity ratio of 50:1 on average for each of the spatial directions
,
, and
. Typical stiffness values are kx = 1.722 ± 0.083 N/m, ky = 1.511 ± 0.034 N/m, and kz = 1.64 ± 0.16 N/m resulting in a quasi-isotropic ratio of the stiffness of 1.1:0.9:1.0 in
:
:
, respectively. The probing repeatability of the developed true 3D-AFM shows a standard deviation of 0.18 nm, 0.31 nm, and 0.83 nm for
,
, and
, respectively. Two CD-line samples type IVPS100-PTB, which were perpendicularly mounted to each other, were used to test the performance of the developed true 3D-AFM: repeatability, long-term stability, pitch, and line edge roughness and linewidth roughness (LER/LWR), showing promising results.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
A new three dimensional (3D) atomic force microscopic (AFM) probe, referred to as the 3D-Nanoprobe, is introduced. The 3D-Nanoprobe is realized by introducing flexure hinge structures to the ...cantilever of a conventional critical dimension AFM (CD-AFM) probe. It has quasi-isotropic stiffness in 3D directions and is thus more powerful for detecting 3D tip-sample interaction forces in AFM measurements. In addition, the stiffness of the 3D-Nanoprobe is balanced to the bending stiffness of slender CD-AFM tips, offering improved 3D sensitivity. In this paper, a design example of a 3D-Nanoprobe based on a CD-AFM probe with a tip nominal diameter of 70 nm is presented. The design parameters are optimized via analytic modelling and the finite element analysis (FEA) method. The simulation results indicate that the designed 3D-Nanoprobe has much better performance than that of the original CD-AFM probe, for instance, its stiffness' anisotropy ratio (including the tip contribution) has been improved from 8:8:1 (x, y, z) to 0.9:0.9:1 (x, y, z). The probing sensitivity is improved by a factor of more than 106, 128 and 1.6 in x-, y- and z-direction, respectively. Moreover, the designed 3D-Nanoprobe has the first bending mode eigenfrequency of 84.4 kHz and the first torsional mode eigenfrequency of 346 kHz. The 3D-Nanoprobe has been manufactured by applying a focused ion beam (FIB) tool. Finally, to detect the full 3D interaction forces by the 3D-Nanoprobe, a new AFM-head prototype which consists of two independently adjustable dual optical levers have been developed.
•Novel method for measurement of single nanowires in terms of mechanical properties.•Nanowires with much larger diameters and stiffnesses can be measured.•Nanomanipulation of nanowires with secured ...placements on the substrate for singular tests.•Usage of AFM to perform topological and mechanical measurements with possible inclusion of electrical tests.
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In this paper, we present the results of mechanical measurement of single nanowires (NWs) in a repeatable manner. Substrates with specifically designed mechanical features were used for NW placement and localization for measurements of properties such as Young's modulus or tensile strength of NW with an atomic force microscopy (AFM) system. Dense arrays of zinc oxide (ZnO) nanowires were obtained by one-step anodic oxidation of metallic Zn foil in a sodium bicarbonate electrolyte and thermal post-treatment. ZnO NWs with a hexagonal wurtzite structure were fixed to the substrates using focused electron beam-induced deposition (FEBID) and were annealed at different temperatures in situ. We show a 10-fold change in the properties of annealed materials as well as a difference in the properties of the NW materials from their bulk values with pre-annealed Young modulus at the level of 20 GPa and annealed reaching 200 GPa. We found the newly developed method to be much more versatile, allowing for in situ operations of NWs, including measurements with different methods of scanning probe microscopy.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The differential adsorption and hydrophobization of S-(2-hydroxyamino)-2-oxoethyl-N,N-dipropyl dithiocarbamate (HAPTC) towards galena and sphalerite, and HAPTC’s selective flotation separation of ...galena from its mixture with sphalerite.
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•S-(2-hydroxyamino)-2-oxoethyl-N,N-dipropyl dithiocarbamate was used as PbS collector.•In situ AFM observed a denser adsorption of HAPTC on galena than sphalerite.•AFM force revealed HAPTC’s selective hydrophobization to galena versus sphalerite.•HAPTC achieved a selective flotation separation of galena from sphalerite at pH 9.•Both dithiocarbamate and hydroxamate groups of HABTC anchored on galena.
Flotation separation is determined by chemical additives which can enlarge the hydrophobicity difference of minerals. Herein, S-(2-hydroxyamino)-2-oxoethyl-N,N-dipropyl dithiocarbamate (HAPTC) was firstly developed for the flotation separation of galena and sphalerite. In situ AFM imaging elucidated a much stronger adsorption affinity of HAPTC towards galena (PbS) than that to sphalerite (ZnS) at pH 6.2 and 9.0. The AFM force findings and the extended DLVO theory analyses indicated that HAPTC adsorption promoted the hydrophobicity of galena surface more significantly than that of sphalerite. The micro-flotation results showed that HAPTC achieved a selective flotation separation of galena against sphalerite at pH around 9.0. FTIR and XPS uncovered that both dithiocarbamate and hydroxamate groups in HAPTC participated in the bonding interaction with Pb sites on galena surface with the formation of Pb-S and Pb-O bonds. The results provide implications on developing novel reagents, and the fundamental understanding of their adsorption and hydrophobization to minerals at nanoscale.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•1250 °C heat treatments enhance the corrosion resistance of AlxCoCrFeNi HEAs.•Homogenization is revealed by the decreased work function variations among phases.•Thermodynamic calculations could ...predict the phase transformation of HEAs.
The present work investigates the homogenization effect of 1250 °C heat treatment on the AlxCoCrFeNi high-entropy alloys (HEAs). The multi-phase microstructures with chemical segregations are inevitable with the increased Al content in the alloys, which cause work function variations and localized corrosion. After heat treatment, the homogenization effect revealed by the microstructure simplification and chemical-segregation reduction leads to the decreased work function variations and the improved corrosion resistance. Thermodynamic calculations that are reliable to predict the phase transformations of the AlxCoCrFeNi HEAs, indicates a further enhancement in corrosion resistance through annealing could be guided for many other HEAs systems.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Atomic Force Microscopy
In article number 2303838, Yingchun Guan, Zhen Zhang, and co‐workers present an ultra‐large scale stitchless atomic force microscopy (AFM) through a synergistic integration ...with a compliant nano‐manipulator. It enables high‐throughput characterization of ultra‐large scale samples without stitching or bow errors, expanding the scanning area of conventional AFMs by two orders of magnitude.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Atomic force microscopy (AFM) has evolved to be one of the most powerful tools for the characterization of material surfaces especially at the nanoscale. Recent development of AFM has incorporated a ...suite of analytical techniques including surface‐enhanced Raman scattering (SERS) technique and infrared (IR) spectroscopy to further reveal chemical composition and map the chemical distribution. This incorporation not only elevates the functionality of AFM but also increases the resolution limitation of conventional IR and Raman spectroscopy. Despite the rapid development of such hybrid AFM techniques, many unique features, principles, applications, potential pitfalls or artifacts are not well known to the community. This review systematically summarizes the recent relevant literature on hybrid AFM principles and applications. It focuses specially on AFM‐IR and AFM‐Raman techniques. Various applications in different research fields are critically reviewed and discussed, highlighting the potentials of these hybrid AFM techniques. Here, the major drawbacks and limitations of these two hybrid AFM techniques are presented. The intentions of this article are to shed new light on the future research and achieve improvements in stability and reliability of the measurements.
Hybrid atomic force microscopy (AFM) combines AFM with spectroscopic techniques such as infrared (IR), Raman and confocal. Hybrid AFM techniques can achieve nanoscale physicochemical characterization of material surfaces with high spatial resolutions. Recent developments and applications of hybrid AFM are summarized with a focus on AFM‐IR and AFM‐Raman and their existing drawbacks and limitations.
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