Atomic Force Micrographs Research Articles

Stable Radical Isoporphyrin Copolymer Prepared with Di(phenylphosphane).

Two diphosphanes with variable-length ligands tested as nucleophiles to prepare isoporphyrin copolymers in the presence of ditolylporphyrin of zinc (ZnT2P) prevented the oxidation of the diphosphine ligand. This paper demonstrates the power of this approach and describes the photoelectrocatalytic properties. The obtained copolymers were characterized by UV-vis spectroscopy, X-ray photoelectron spectroscopy, atomic force micrograph (AFM), EQCM (Electrochemical Quartz Cristal Microbalance) and electrochemistry. Their impedance properties (EIS) were studied and their photovoltaic performances were also investigated by photocurrent transient measurements under visible light irradiation.

Cutting nanodisks in graphene down to 20 nm in diameter

A direct focused He+ beam direct machining is presented to fabricate solid-state nano-disk at the surface of a graphene multilayer micro-flake deposited on an Au/Ti/sapphire surface. At irradiation doses larger than 5.0 × 1017 ions cm−2 and with a beam size well below 1 nm, graphene disks down to 20 nm in diameter have been machined with for nano-disk down to 50 nm in diameter, a central hole for preparing the positioning of a rotation axle. The local heat generated by this irradiation is inducing a partial graphene amorphization and deformation, leading to a complete graphene nano-disk vaporization at doses larger than 5 × 1018 ions cm−2. A dry transfer printing technique followed by a graphene surface cleaning was used to transfer the nano-disks from its initial surface to a fresh and clean surface. Tapping mode atomic force micrograph have been recorded to follow the vaporization as a function of the He+ dose to confirm the graphene solid-state nano-disk fabrication limit to about 20 nm with this process.

Reconstruction of laser-induced microstructures temperature profiles

Metallic microstructures are currently widely used in micro-optoelectronics, sensorics, microfluidics, and other applications. A promising direction in the creation of such microstructures is pulsed laser processing of thin metal films. To improve laser technologies and simulate ongoing processes, data on the temperature fields that arise during laser exposure are needed. The article shows that the temperature distribution on the surface of a material during pulsed laser heating can be obtained from optical, scanning electron or atomic force micrographs. The proposed approach opens up the possibility of estimating temperature fields from archival photographs of various microstructures.

Tailoring the surface properties of molybdenum oxytelluride thin films by its compositional ratio

In this work, RF magnetron co‐sputtering was used to fabricate molybdenum oxytelluride thin films with different atomic ratios. Scanning electron micrographs and atomic force micrographs revealed that pure Mo thin films were segregated. Thin films with 40% Te content portrayed needle‐like structures and thus had the largest Rq value of 2.48 nm. Contact angle measurements further supported the findings as the thin films with 40% Te content were the most hydrophobic. X‐ray photoelectron spectroscopy results revealed that the major oxidation states of Mo from Te‐poor to Te‐rich TFs were changed from high (+6) to low (+4 and/or +2). X‐ray diffraction data showed that peaks pertaining to molybdenum oxide species appeared, notably at 33.048° and 33.115°. Ultraviolet photoelectron spectroscopy and Kelvin probe measurements evinced that the work function increases with increasing Te content. Four‐point probe measurements revealed that molybdenum oxytelluride thin films tend to have higher electrical conductivity than pure Mo and Te thin films.

Experimental investigation of anti-corrosive behaviour of Beta vulgaris: A green approach

The loss of metals due to corrosion can be prevented using green inhibitors. Using natural and eco-friendly plant products is futuristic, preventing the environment from toxic and harmful chemicals. The present study aimed to investigate whole beetroot (BR, Beta vulgaris) for its anti-corrosion behaviour by galvanostatic polarization and electrochemical impedance techniques at a temperature between 298 K- 328 K. The temperature study would help in proposing BR's adsorption mechanism on metal surfaces. The maximum inhibition efficiency of 94% at 298 K for 5% BR was observed, whereas a minimum of 75% was obtained for 1% BR at 328 K. It was found to be a mixed-type inhibitor that followed Langmuir isotherm. From thermodynamic studies, ΔGoads was found to be -13.64 kJ/mol, which revealed that BR adsorbed physically on the surface of mild steel. Rct values increased while Cdl values decreased on exposure of metal surface with BR extract. The scanning electron micrographs (SEM) and atomic force micrographs (AFM) witnessed the formation of a protective layer on the mild steel surface, which served as a barrier between the metal and corrosive medium. The present study provides a remedy for the financial and structural losses due to metal corrosion in an acidic medium.

Gemini surfactant‐stabilized Pd nanoparticles: Synthesis, characterization, and catalytic application in the reduction and reductive acetylation in the water solvent

A series of Gemini surfactants (GSs) were prepared by reacting alkyl bromides with N,N,N′,N′‐tetramethyl ethylenediamine. Various alkyl bromides used in for the preparation of GSs are 1,3‐dibromo ethane, 1,3‐dibromoethane, 1‐Bromohexane, 1‐Bromooctane, 1‐Bromooctadecane and 1‐Bromooctadodecane. Different solvents and temperatures were investigated for the formation of gels of prepared GSs. Among all, 1‐Bromooctane, 1‐Bromooctadecane‐derived GSs formed organogels. Thus, synthesized long‐chain organogels have been used to stabilize Pd NPs. The Pd NPs formation initially confirmed through Ultraviolet‐visible, Scanning Electron Microscopy, and Atomic Force Micrograph studies. Later Fourier Tansform Infra Red, Thermo Gravimetric Analysis, and Zeta potential studies were also carried out to understand their properties extensively. The Pd NPs stabilized by GSs have been identified as a potential catalyst in the reductive N‐acetylation of nitroaromatics at room temperature. The N‐acetylated products were obtained in good yields in an aqueous medium. In addition, the potentiality of our catalyst has been also evaluated in the reduction of nitroaromatics in an aqueous medium, which is a green protocol. Further, the semi‐empirical geometry optimizations of active GS gel confirmed the dihedral angle of 59° in between the two octyl moieties calculated from computational studies. The rheological properties such as amplitude sweeping, viscosity shear profile of the gel have also been studied.

Superhydrophilicity and Antifouling Behavior in Electrochemically Oxidized Nanocrystalline Pseudographite

Electrochemical oxidation of GUITAR (pseudoGraphite from the University of Idaho Thermolyzed Asphalt Reaction) produces a surface that exhibits superhydrophilic properties. This surface contains 20.7% relative oxygen abundance, giving it a heightened affinity for water relative to the pristine material. Scanning electron and atomic force micrographs reveal spherical, bubble-like structures on GUITAR, indicating a higher surface roughness (Rq = 300–400 nm) over the predominantly smooth titanium substrate (Rq = 94.5 nm). Combining an intrinsic affinity toward water with a heightened surface roughness produces a material with an apparent water contact angle of 0°. The synergistic effects of a superhydrophilic surface that can function as an electrode result in an electrocatalyst material that is highly resistant to fouling. When stored in water, oxidized GUITAR (Ox-GUITAR) completely resists fouling by volatile organic compounds for the duration of testing (72 h). When fouled directly with a drop of oil, the residue can be removed using a simple water rinse. The removal of oil residues from carbon surfaces is typically not possible without the use of solvents, surfactants, or mechanical exfoliation. This combination of properties opens Ox-GUITAR to a broad array of possible applications, such as implantable electrodes, field sensors, or water-quality monitoring.

Structure, magnetic morphology and magnetization correlations in pulsed laser deposited CoFe[formula omitted]O[formula omitted] ([formula omitted]) thin films

The present paper reports a complete study on the correlation between structure, morphology, and magnetic properties of (111)-oriented cobalt ferrite (CoFe2O4) thin films with varying film thickness. The CoFe2O4 (CFO) thin films were deposited on Pt-coated Si substrate by pulsed laser deposition (PLD) at 550 °C. The x-ray diffraction (XRD) data confirms the (111)-oriented growth of the cobalt ferrite films. The in-plane morphology of the films in the field emission scanning electron micrographs ensure the Stranski–Krastanov growth mechanism, and the atomic force micrographs confirms the effect of lattice relaxation on the morphology of the films with varying thickness. The possible cation distributions for the samples were determined from the Raman spectroscopy, which revealed the crystal structure-magnetic property correlations in cobalt ferrite films. The magnetic hysteresis (M−H) loops show a significant spin reorientation by showing the variation between the in-plane (IP) and out-of-plane (OP) magnetization. The presence of a kink on the OP M−H loops and its variation with film thickness clearly establishes the existence of competing magnetic anisotropies in the films. The high coercivity (HC) values observed for OP magnetization of cobalt ferrite films with thicknesses 115 nm and 125 nm may be explored for possible room-temperature (RT) device applications.

High amount of lecithin facilitates oral delivery of a poorly soluble pyrazoloquinolinone ligand formulated in lipid nanoparticles: Physicochemical, structural and pharmacokinetic performances

Preclinical development of deuterated pyrazoloquinolinone ligands, promising drug candidates for various neuropsychiatric disorders, was hindered by unusually low solubility in water and oils. DK-I-60-3 (7-methoxy-d3-2-(4-methoxy-d3-phenyl)-2,5-dihydro-3Hpyrazolo[4,3-c]quinolin-3-one) is one of such pyrazoloquinolinones, and we recently reported about increased oral bioavailability of its nanocrystal formulation (NC). Lipid nanoparticles (LNP) with a high concentration of lecithin, which enhances loading capacity of the lipid matrix, may give rise to further improvement. After preformulation studies by differential scanning calorimetry and polarized light microscopy, LNP were prepared by the hot high pressure homogenization, and characterized in terms of particle size, morphology, and encapsulation efficacy. The layered structure visible on atomic force micrographs was confirmed by nuclear magnetic resonance. Obtained formulations were desirably stable, with small particle size (<100 nm), and high encapsulation efficacy (>99 %). Lecithin was partially fluid and most probably located in the outer shell of the particle, together with DK-I-60-3. While the hydrophobic part of polysorbate 80 was completely immobilized, its hydrophilic part was free in the aqueous phase. In oral neuropharmacokinetic study in rats, an around 1.5-fold increase of area under the curve with LNP compared to NC was noticed both in brain and plasma. In bioavailability study, F value of LNP (34.7 ± 12.4 %) was 1.4-fold higher than of NC (24.5 ± 7.8 %); however, this difference did not reach statistical significance. Therefore, employment of LNP platform in preclinical formulation of DK-I-60-3 imparted an incremental improvement of its physicochemical as well as pharmacokinetic behavior.

Use of Polystyrene Nanoparticles as Collectors in the Flotation of Chalcopyrite

This study proposes the use of polymeric nanoparticles (NPs) as collectors for copper sulfide flotation. The experimental phase included the preparation of two types of polystyrene-based NPs: St-CTAB and St-CTAB-VI. These NPs were characterized by Fourier-Transform Infrared (FTIR) spectroscopy and dynamic light scattering (DLS). Then, microflotation tests with chalcopyrite under different pH conditions and nanoparticle dosages were carried out to verify their capabilities as chalcopyrite collectors. In addition, the zeta potential (ZP) measurements of chalcopyrite in the presence and absence of NPs were carried out to study their interaction. Lastly, some Atomic Force Micrographs (AFM) of NPs and Scanning Electronic Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analysis of NPs on the chalcopyrite surface were conducted to analyze the size, the morphology and their interaction. The results obtained at pH 6 and pH 8 show that the NPs under study can achieve a chalcopyrite recovery near or higher than that obtained with the conventional collector. In this study, it was possible to observe that the NPs functionalized by the imidazole group (St-CTAB-VI) achieved better performance due to the presence of this group in its composition, allowing to achieve a greater affinity with the surface of the mineral.

Optical Manipulation of Gb3 Enriched Lipid Domains: Impact of Isomerization on Gb3 -Shiga Toxin B Interaction.

The plasma membrane is a complex assembly of proteins and lipids that can self-assemble in submicroscopic domains commonly termed "lipid rafts", which are implicated in membrane signaling and trafficking. Recently, photo-sensitive lipids were introduced to study membrane domain organization, and photo-isomerization was shown to trigger the mixing and de-mixing of liquid-ordered (lo ) domains in artificial phase-separated membranes. Here, we synthesized globotriaosylceramide (Gb3 ) glycosphingolipids that harbor an azobenzene moiety at different positions of the fatty acid to investigate light-induced membrane domain reorganization, and that serve as specific receptors for the protein Shiga toxin (STx). Using phase-separated supported lipid bilayers on mica surfaces doped with four different photo-Gb3 molecules, we found by fluorescence microscopy and atomic force microscopy that liquid disordered (ld ) domains were formed within lo domains upon trans-cis photo-isomerization. The fraction and size of these ld domains were largest for Gb3 molecules with the azobenzene group at the end of the fatty acid. We further investigated the impact of domain reorganization on the interaction of the B-subunits of STx with the photo-Gb3 . Fluorescence and atomic force micrographs clearly demonstrated that STxB binds to the lo phase if Gb3 is in the trans-configuration, whereas two STxB populations are formed if the photo-Gb3 is switched to the cis-configuration highlighting the idea of manipulating lipid-protein interactions with a light stimulus.

Boosting Energy Storage of Poly(vinylidene difluoride) Nanocomposite Based Flexible Self-Standing Film with Low Amount of Hydroxylated V2O5

Polymer-ceramic based nanocomposite dielectric materials have become an attraction for researchers due to their lightweight and high dielectric breakdown strength as well as good dielectric properties. We have synthesized poly(vinylidene difluoride) (PVDF)/hydroxylated-V2O5 (Hy-V2O5) ferroelectric polymer nanocomposite self-standing film, with an average thickness of 0.07 ± 0.005 mm. The phase identification, surface analysis, and structural analysis were performed using differential scanning calorimetry, X-ray photoelectron spectroscopy analysis, and X-ray diffraction, respectively. The analysis of atomic force micrographs reveals lower surface roughness of the nanocomposite films and confirms that the film is suitable for energy storage rather than charge transport with the help of the isotropic power spectral density (PSD) profile. The loading of a low amount of Hy-V2O5 filler in PVDF significantly enhances the ferroelectric polarization, making it highly suitable for high energy storage applications. Enhancement of the dielectric constant (from ∼9 to 29.86) and polarization (Pmax for PVDF = 0.86 μC/cm2 to Pmax for PVDF/Hy-V2O5 = 2.7 μC/cm2 at the 1000 kV/cm field) is obtained. The energy density for the nanocomposite increased to 220% of that of the pure PVDF. Due to the low amount of filler, there is no substantial reduction in the dielectric breakdown strength of the nanocomposite, which is maintained at 1766.93 kV/cm.

Carrier properties of Bi(111) grown on mica and Si(111)

A comparison is presented between properties of Bi(111) films grown by Stranski-Krastanov epitaxy on Si(111) 7 $\ifmmode\times\else\texttimes\fi{}$ 7 and by van der Waals epitaxy on mica substrates. Thin film morphologies and electronic transport properties of Bi(111) films of variable thickness are investigated for each growth method. Atomic force micrographs for Bi(111) films on mica reveal clearly defined triangular regions consisting of layered steps with height 0.4 nm, corresponding to the Bi(111) bilayer height. Variable-temperature electronic transport measurements show the existence of a quantum confinement-induced energy gap in the film interiors, resulting in a semimetal-to-semiconductor transition. Magnetotransport analysis in a three-carrier model including metallic electrons in surface states and electrons and holes in the films' interiors provides a detailed study of densities, mobilities, and mean-free paths of the three carrier types. Improved electronic transport properties are found in Bi(111) films of higher thickness on mica compared to on Si(111), a likely result of the largely strain-free van der Waals epitaxial growth.

A low power 50 Hz argon plasma for surface modification of polytetrafluoroethylene

The characteristics of a low power 50 Hz argon plasma for surface treatment of polytetrafluoroethylene (PTFE) film is presented in this article. The current–voltage behavior of the discharge and time-varying intensity of the discharge showed that a DC glow discharge was generated in reversed polarity at every half-cycle. At discharge power between 0.5 and 1 W, the measured electron temperature and density were 2–3 eV and ∼108 cm−3, respectively. The optical emission spectrum of the argon plasma showed presence of some ‘impurity species’ such as OH, N2 and H, which presumably originated from the residual air in the discharge chamber. On exposure of PTFE films to the argon glow plasma at pressure 120 Pa and discharge power 0.5 to 1 W, the water contact angle reduced by 4% to 20% from the original 114° at pristine condition, which confirms improvement of its surface wettability. The increase in wettability was attributed to incorporation of oxygen-containing functional groups on the treated surface and concomitant reduction in fluorine as revealed by the XPS analysis and increase in surface roughness analyzed from the atomic force micrographs. Ageing upon storage in ambient air showed retention of the induced increase in surface wettability.

Study of the Surface Texture of Magnetron Sputtered Transparent Conducting ZnO:Al films by Atomic Force Microscopy

Abstract: Transparent conducting ZnO: Al films with proper surface texture have been developed on glass substrate at 3500C by rf-magnetron sputtering under Ar and Ar+O2 gas ambients. ZnO:Al films exhibit low resistivity (~ 8.9x10-4 Ω-cm), and high optical transmittance (T~ 85% to 90%) in visible region. Study of surface texture ZnO:Al films by dry (hydrogen plasma) etching and wet chemical etching in diluted 0.5% HCl acid solution have been reported in this paper. Due to hydrogen plasma etching surface topography as well as morphology of ZnO:Al films is modified into suitable texture for light scattering. But surface texture is deteriorated drastically for wet chemical etched films. Electrical properties have been improved slightly and optical transmittance remains undeviated due to H-plasma etching but significant changes in electrical and optical properties have been observed in wet chemical etching. Keywords: ZnO:Al films, Surface Texture, Wet Chemical etching, Atomic Force Micrograph, Thin film solar cell

Selectivity enhancement of oxidative degraded reverse osmosis membrane by chitosan–tannic acid treatment

AbstractReverse osmosis membrane elements suffer oxidative degradation during operation thereby resulting in increased salt passage. The present article demonstrates the novel approach to bind a chitosan–tannic acid layer above the degraded reverse osmosis membrane to make a supramolecular assembly over loosened polyamide layer to increase the selectivity performance. Chitosan being naturally occurring linear polysaccharide, its biodegradability, nontoxicity, antimicrobial property make it a promising candidate for membrane surface modification. Tannic Acid functions as cross‐linking agent, contains many polyphenolic compound, and was found suitable to bind with chitosan and form a supramolecular layer over polyamide. The present article showed the increase in salt rejection upto 33.17% of oxidative degraded reverse osmosis membrane by chitosan–tannic acid treatment. The selectivity enhancement was significant in case of membrane modified with chitosan–tannic acid supramolecular assembly. The modified membranes exhibited lower leaching as compared to only tannic acid treated membrane. They were characterized for morphology, surface features and chemical structure by scanning electron micrographs, atomic force micrographs, Fourier transform infrared spectroscopy. Moreover, the differential scanning calorimetry analysis was done to evaluate the glass transition temperature of modified membrane. Stress–strain behavior of modified membranes were analyzed. This article proposes as novel approach to enhance the selectivity of degraded membrane.

Enhanced selective ammonia detection of spray deposited Cd-doped β-Ga2O3 thin films with low hysteresis effect

The Ga2O3 thin films at different concentrations (at %) of Cd dopant were deposited using spray pyrolysis technique. The X-ray diffraction patterns revealed Cd-doped β-Ga2O3 thin film are in monoclinic crystal structure with (2 0 1) orientation. Atomic force micrographs depict the change in morphology upon Cd dopant. At ambient temperature (∼30 °C), the results of ammonia sensing measurements of 4 at % Cd-doped Ga2O3 thin films point out the low-level detection (0.5 ppm) of ammonia with good sensing response (233 %), higher sensitivity (26 Ω/m), fast response-recovery time (3 s and 14 s), better selectivity, low hysteresis, and higher stability.

Grapefruit Oil and Cobalt Nitrate-Loaded Polyurethane Hybrid Nanofibrous Scaffold for Biomedical Applications

The goal of this work is to fabricate a new composite based on polyurethane (PU), grapefruit (GP) oil, and cobalt nitrate [Co(NO3)2] using an electrospinning technique. Morphology results revealed the reduction in the fiber diameter of the composites compared to pristine PU control. The interaction of PU with GP and Co(NO3)2 was confirmed by hydrogen bond formation evident in infrared analysis. The fabricated PU/GP composites depicted a more hydrophobic behavior, while PU/GP/Co(NO3)2 showed a hydrophilic behavior than the pristine PU. Atomic force micrographs (AFM) revealed that the developed composites showed a decrease in the surface roughness (Ra) compared to PU. The addition of GP and Co(NO3)2 improved the mechanical strength of the pristine PU. The blood compatibility assays concluded not only the increase in blood clotting levels but also the less toxic nature of the fabricated composites compared to the pristine PU. Hence, the newly designed composites possessing outstanding physicochemical and biological properties may be used as a potential candidate for scaffolding in tissue engineering applications.

Analysis of the structure and properties of dextran produced by Weissella confusa

An EPS produced by Weissella confusa H2 was purified through Sephadex G-100, and the preliminary structure characteristics and biological activities of H2 EPS were analyzed. Molecular mass of purified H2 EPS was 2.705 × 106 Da as measured with gel permeation chromatography (GPC). Composition of monosaccharides, nuclear magnetic resonance (NMR) spectroscopy spectroscopy and fourier transform infrared (FT-IR) showed that the EPS was a linear homopolysaccharide, mainly constituted of glucose and it is suggested that the EPS was dextran with α-(1 → 6) glycosidic bonds and a few α-(1 → 3) branches. Atomic force micrograph (AFM) and scanning electron microscopy (SEM) analysis of dextran further revealed sheets branched microstructure anchored with many irregular protuberances in aqueous solution. The XRD pattern reflected non-crystalline amorphous nature. In addition, the solubility, water-holding capacity, thermal property, rheological property and heavy metal chelating activity of the purified H2 dextran were determined. The dissolution percentage and water holding capacity of the dextran were 98.78 ± 1.37% and 426.03 ± 7.26%, respectively. The dextran exhibited good hydrophilicity, thermal stability and heavy metal chelating activity. Rheological studies exhibited rotational speed, pH, temperature, metal ions solutions dependent semiviscous nature. These results support its use as an additive in the food and environmental protection fields.

Mixed phase FeTe: Fe2TeO5 nanopebbles through solution chemistry: Electrochemical supercapacitor application

Mixed phase of iron telluride based thin films consisting of nanopebbles has been grown successfully over conducting stainless steel (SS) substrate through successive ionic layer adsorption reaction (SILAR) process. Crystal structural and elemental states through XPS revealed clear indication of FeTe: Fe 2 TeO 5 mixed phase growth and well supported through FTIR studies. Agglomeration of embedded quantum dots forming nanopebbles like surface architecture resulting in enhanced hydrophilic nature evident through contact angle and higher surface roughness by atomic force micrographs found beneficial as more electroactive surface area for electrolyte ions to interact. This helped to achieve a significant specific capacitance of 591 F/g (166 mF/cm 2 ) @3 mV/s potential scan rate and, 107 F/g (30 mF/cm 2 ) @0.4 mA/cm 2 in NaCl electrolyte. Performed electrochemical impedance spectroscopy (EIS) studies explored clear insight of the solution and charge transfer resistances, and relaxation time constant. Iron telluride based thin film clearly demonstrates very high value of pseudo capacitive contribution than the electric double layer due to the intrinsic pseudocapacitive behavior of mixed phase. • First report on iron telluride based (FeTe: Fe 2 TeO 5 ) thin film synthesis using simple SILAR method and successfully employed as supercapacitor electrode. • Nanopebbles embedded with quantum dots agglomeration responsible for more electrochemical active sites. • Notable specific capacitance of 591 F/g (426 C/g or 166 mF/g) at 3 mV/s by CV and 107 F/g (30 mF/cm 2 ) at 0.4 mA/cm 2 by GCD studies. • Enhanced inner (pseudo q p ) charge storage contributions than outer (EDLC q d l ).