We report on the analysis of individual dye loaded block copolymer (BCP) vesicles via a combination of confocal laser scanning microscopy (CSLM)/fluorescence lifetime imaging microscopy (FLIM) on the ...one hand and atomic force microscopy (AFM) on the other hand. AFM measurements on ATTO 647N-loaded poly(styrene-
-poly(acrylic acid)) (PS
-PAA
) vesicles were carried out with high spatial resolution and afforded morphology and dimensions of BCP vesicles on solid substrates. By contrast the CSLM and FLIM data are diffraction limited, but from the time resolved fluorescence data information on the local vicinity of the reporter dye can be extracted. In the combined experiment individual dye-loaded vesicles and vesicle aggregates were discerned, analyzed metrologically by AFM and in more detail by CSLM and FLIM. On the basis of FLIM data the partitioning of the reporter dye was analyzed. The dye resides preferentially in the hydrophilic corona inside the vesicles. The dye concentration in the polymersome was about 90 times higher than in the solution used for encapsulation. These results underline that the combination of AFM with sensitive optical techniques, especially FLIM, is a promising approach for obtaining a deeper understanding of molecular interactions and nanoenvironments in supramolecular macromolecular structures and beyond.
Tapping mode atomic force microscopy (AFM), also known as amplitude modulated (AM) or AC mode, is a proven, reliable, and gentle imaging mode with widespread applications. Over the several decades ...that tapping mode has been in use, quantification of tip–sample mechanical properties such as stiffness has remained elusive. Bimodal tapping mode keeps the advantages of single-frequency tapping mode while extending the technique by driving and measuring an additional resonant mode of the cantilever. The simultaneously measured observables of this additional resonance provide the additional information necessary to extract quantitative nanomechanical information about the tip–sample mechanics. Specifically, driving the higher cantilever resonance in a frequency modulated (FM) mode allows direct measurement of the tip–sample interaction stiffness and, with appropriate modeling, the set point-independent local elastic modulus. Here we discuss the advantages of bimodal tapping, coined AM-FM imaging, for modulus mapping. Results are presented for samples over a wide modulus range, from a compliant gel (∼100 MPa) to stiff materials (∼100 GPa), with the same type of cantilever. We also show high-resolution (subnanometer) stiffness mapping of individual molecules in semicrystalline polymers and of DNA in fluid. Combined with the ability to remain quantitative even at line scan rates of nearly 40 Hz, the results demonstrate the versatility of AM-FM imaging for nanomechanical characterization in a wide range of applications.
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IJS, KILJ, NUK, PNG, UL, UM
DNA Origami
In article number 2308776, Chalmers Chau, Christoph Wälti, and co‐workers introduce the use of solid‐phase reversible immobilization (SPRI) beads as a scalable, high‐throughput, and ...automatable purification method to scale up the production of DNA origami nanostructures, with the aid of liquid handling robot. This artwork illustrates a DNA origami structure in the center and below a robot whose silhouette represents the unification of DNA nanotechnology and modern robotic.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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•New synthesized S-Thiazine was characterized using NMR and IR spectroscopy.•The New synthesized acted as mixed-type corrosion inhibitor.•Surface analysis using SEM, EDS and AFM ...study.•The adsorption properties were confirmed by DFT calculations and MC simulations.
This potential work presents a new organic molecule as a corrosion inhibitor of mild steel in HCl solution (1.0 M HCl).The organic molecule was elucidated by IR, 1H NMR and 13C NMR spectroscopy.The corrosion inhibiting effect was achieved by techniques electrochemical techniques such as Potentio-dynamic polarization (PDP) and impedance spectroscopy (EIS).The surface of the steel after corrosion tests has been identified by scanning electron spectroscopy (SEM), energy dispersive spectroscopy (EDS) and atomic force microscope (AFM) spectroscopy. The experimental studies were confirmed by the calculations of density functional theory (DFT) and Monte Carlo simulations (MC). The theoretical, experimental studies and analytical techniques clearly show that this molecule is a good corrosion inhibitor (91 %) of steel in HCl solution. The polarization studies show that this inhibitor acts as a mixed type inhibitor. The thermodynamic parameters show that this molecule chemically adsorbed on the surface of the steel following the isotherm of Langmuir.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Corrosion inhibition of green inhibitor was studied by experimental and theoretical methods.•The experiments demonstrated a mixed type corrosion inhibition behavior.•EIS results showed the maximum ...inhibition efficiency of about 95%.•MC and MD simulations evidenced the inhibitors adsorption on the steel surface.
This study concerns with mild steel corrosion inhibition in 1M HCl solution protected with different concentrations of Lemon Balm extract. Electrochemical and theoretical approaches are utilized for approaching this goal. The type of functional groups in the active components present in the Lemon Balm extract (LB.E) was examined through UV–visible analysis, Fourier Transform Infrared (spectroscopy) (FT-IR) and Raman spectroscopy. According to the electrochemical impedance spectroscopy (EIS) test results the maximum inhibition efficiency of about 95% was obtained in the solution containing 800 ppm LB.E. Potentiodynamic polarization test results revealed that in the presence of LB.E the rates of anodic steel dissolution and cathodic hydrogen evolution reactions significantly decreased and a mixed inhibition effect was obtained. Surface studies were done by contact angle test, atomic force microscopy (AFM) and scanning electron microscopy (SEM). Results revealed that the steel surface damage as a result of HCl solution attack significantly decreased by addition of 800 ppm LB.E. In addition, deposition of a highly hydrophobic film composed of organic compounds of inhibitors on mild steel surface was demonstrated by contact angle test results. The excellent corrosion inhibition effect of LB.E on mild steel in HCl solution is related to the adsorption of active inhibitive compounds such as caryophyllene, germacrene, citral, luteolin, chlorogenic acid and rosmarinic acid on the anodic/cathodic places of mild steel surface. Furthermore, the theoretical results derived from Monte Carlo, molecular dynamics and quantum mechanics techniques evidenced the inhibitors adsorption onto steel substrate through donor-acceptor interactions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The characterization of micro-surface mechanical and electrical properties of the natural rock materials remains inadequate, and their macroscopic performance can be better comprehended by ...investigating the surface properties. With this purpose, the present research focuses on characterizing the micro-surface morphology, Derjaguin-Muller-Toporov (DMT) modulus, adhesion, and potential of granite, shale, and limestone by employing the atomic force microscope (AFM) as a pioneer attempt. The results show that the micro-surface morphology of the rock fluctuates within hundreds of nanometers, among which the granite micro-surface is comparatively the smoothest, followed by limestone. The morphology of the shale is the roughest, indicating that the regional difference of shale micro-surface is dominant. The distribution of the adhesion on rock micro-surface is uneven; the average adhesion of eight measuring areas for shale is 23.93 nN, accounting for three times of granite and limestone, while the surface DMT modulus of shale is relatively lower than granite and limestone. It is inferred from the obtained results that higher surface adhesion is helpful to the gas adsorption of shale, and the lower surface DMT (elastic) modulus is useful to the formation of fractures and pores. Thus, these two are the micromechanical basis of shale gas adsorption. Additionally, introducing a method to reduce the surface adhesion will benefit the exploration of unconventional resources such as shale gas. The micro-surface of the three types of rocks all shows electricity, with average potential ranging from tens of millivolts to hundreds of millivolts. Besides, the micro-surface potential of the rocks are heterogeneous, and both positive and negative points can be found. The existence and uneven distribution of micro-surface potential provide a robust physical basis for the electromagnetic radiation generated by rock fracture under loading. This study offers a new method for revealing the adsorption characteristics of unconventional gas reservoir rocks and the electromagnetic radiation mechanism of the rock fracture.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
Highly relaxed InGaN templates with an effective In-content of ∼10% that exhibit reduced
V-pit
density and an improved surface roughness are reported using the semibulk (SB) growth approach. ...This was achieved by the insertion of five period high temperature SB (HTSB) InGaN SB regions. This report demonstrates that better quality InGaN templates can be achieved by the insertion of HTSB within the templates, rather than by ending the templates with a superlattice structure or by refilling the pits with GaN interlayers. Three SB samples were grown with and without the HTSB layers. Using secondary-ion mass spectrometry, photoluminescence, and x-ray diffraction, the effective In-content of the templates was determined to be 9.6%, 5.8%, and 8.7%. Using atomic force microscopy, the surface roughness was found to improve from 4.4 to 1.7 nm by using the two HTSB regions, and the average
V-pit
density and depth improved from 7.6 × 10
−7
to 4.5 × 10
−7
cm
−2
and 8.2 to 2.8 nm, respectively. Also, the maximum
V-pit
depth was reduced from about 30.5 nm to about 9.6 nm in the sample with the HTSB regions. Two LEDs were studied, one with both HTSB regions, and one with only the topmost HTSB. The optical power density of the LED with both HTSB regions was 1.4 times higher at the peak injection current, displayed a ∼1.3 times higher external quantum efficiency peak, and a delay of the EQE droop onset. These results show that higher In-content SB templates can be improved with the implementation of a modified growth approach.
In article number 1803273, Lianqing Liu and co‐workers propose a unique mask‐free and marker‐free lithography technique to fabricate a sub‐micrometer‐sized 2D material thin‐film transistor using the ...phase mode of atomic force microscopy. This method does not change the chemical, physical, and electrical properties of 2D materials. It offers a flexible, easy, effective, and low‐cost way to fabricate prototypes of sub‐micrometer‐sized devices, and provides the opportunity to explore the potential performance of 2D materials.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
•We present a study in characterizing tip wear of a high speed AFM on four different samples and under different measurement conditions. Our results indicate the dominance of tip breakage in ...high-speed AFM measurements.•To understand the mechanism of tip breakage, we modelled and simulated the tip-sample interaction. The results indicate that the tip-sample interaction force increases dramatically in measurement scenarios of steep surfaces.•Detailed methods for tip characterization and wear test procedures are presented in the paper.
Tip abrasion is a critical issue particularly for high-speed atomic force microscopy (AFM). In this paper, a quantitative investigation on the tip abrasion of diamond-like-carbon (DLC) coated tips in a high-speed metrological large range AFM device has been detailed. Wear tests are conducted on four different surfaces made of silicon, niobium, aluminum and steel. During the tests, different scanning speeds up to 1 mm/s and different vertical load forces up to approximately 33.2 nN are applied. Various tip characterization techniques such as scanning electron microscopy (SEM) and AFM tip characterizers have been jointly applied to measure the tip form change precisely. The experimental results show that tip form changes abruptly rather than progressively, particularly when structures with steep sidewalls were measured. This result indicates the increased tip breakage risk in high-speed AFM measurements. To understand the mechanism of tip breakage, tip-sample interaction is modelled, simulated and experimentally verified. The results indicate that the tip-sample interaction force increases dramatically in measurement scenarios of steep surfaces.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Endophytic fungal supernatant mediated silver nanoparticles (AgNPs).•Formations of AgNPs were confirmed by UV-vis, FTIR, XRD, DLS, EDS, TEM and AFM.•The synthesised AgNPs show good ...antimicrobial activity.
In this study, biological synthesis of silver nanoparticles (AgNPs) from supernatant of endophytic fungus Alternaria sp. isolated from the healthy leaves of Raphanus sativus is studied. The synthesized AgNPs are characterized using UV-vis spectroscopy and Fourier transform-infrared spectroscopy (FTIR). The structural analysis is done by powder X-ray diffraction (XRD) method. The stability of AgNPs is studied by dynamic light scattering (DLS) method. The size and shape of AgNPs are observed by transmission electron microscopy (TEM) and atomic force microscopy (AFM) and found to be spherical with an average particles size of 4–30nm. Further, these AgNPs have been found to be highly toxic against human pathogenic bacteria, suggesting the possibility of using AgNPs as efficient antibacterial agents.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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