Different Types Of Morphology Research Articles

Factors Controlling Complex Morphologies of Isomorphous Metal-Organic Frameworks.

We demonstrate here how nitrate salts of bivalent copper, nickel, cobalt, and manganese, along with an achiral organic ligand, assemble into various structures such as symmetrical double-decker flowers, smooth elongated hexagonal bipyramids, and hexagonal prisms. Large morphological changes occur in these structures because of different metal cations, although they maintain isomorphous hexagonal crystallographic structures. Metal cations with stronger coordination to ligands (Cu and Ni) tend to form uniform crystals with unusual shapes, whereas weaker coordinating metal cations (Mn and Co) produce crystals with more regular hexagonal morphologies. The unusual flower-like crystals formed with copper nitrate have two pairs of six symmetrical petals with hexagonal convex centers. The texture of the petals indicates dendritic growth. Two different types of morphologies were formed by using different copper nitrate-to-ligand ratios. An excess of the metal salt results in uniform and hexagonal crystals having a narrow size distribution, whereas the use of an excess of ligand results in double-decker morphologies. Mechanistically, an intermediate structure was observed with slightly concave facets and a domed center. Such structures most likely play a key role in the formation of double-decker crystals that can be formed by fusion processes. The coordination chemistry results in isostructural chiral frameworks consisting of two types of continuous helical channels. Four pyridine units from four separate ligands are coordinated to the metal center in a plane having a chiral (propeller-type) arrangement. The individual double-decker flower crystals are homochiral and a batch consists of crystals having both handedness.

Microanalysis of TiN phases formed in inclusions of electrogas weld metal

This study has been conducted to confirm the formation of TiN phase in the electrogas (EG) weld metal and, if it formed, to identify the nucleation potency of TiN for acicular ferrite. To facilitate this, a high-nitrogen EG weld meal deposited using a very high heat input was chosen. Inclusion analyses were mostly carried out in a scanning electron microscope (SEM) and analytical transmission electron microscope (TEM) equipped with energy dispersive analyzer (EDS) and electron energy loss spectroscopy (EELS). It was confirmed that the inclusions were nearly fully covered by TiO layer alloyed with a small amount of nitrogen, this TiO layer being partly coated with TiN phases having two different types of morphology: layer-type or patch-type. The layer-type was identified to be nearly pure TiN, being formed with a thickness of 10 nm on the outer surface of thick TiO layer. The patch-type appeared to be formed on the TiN/TiO layer and was characterized by its fine lamellar mixture of TiN and (Al,Mn)-oxide. As all these phases formed on the inclusion surface, they were suspected to influence the nucleation potency of inclusions but the relative potency of these phases to TiO layer was not clearly understood.

Electrochemical Immunosensor for the Determination of Antibodies against Prostate-Specific Antigen Based on ZnO Nanostructures.

In this study, ZnO nanostructures with different types of morphologies and particle sizes were evaluated and applied for the development of an immunosensor. The first material was composed of spherical, polydisperse nanostructures with a particle size in the range of 10-160 nm. The second was made up of more compact rod-like spherical nanostructures with the diameter of these rods in the range of 50-400 nm, and approximately 98% of the particles were in the range of 20-70 nm. The last sample of ZnO was made up of rod-shaped particles with a diameter of 10-80 nm. These ZnO nanostructures were mixed with Nafion solution and drop-casted onto screen-printed carbon electrodes (SPCE), followed by a further immobilization of the prostate-specific antigen (PSA). The affinity interaction of PSA with monoclonal antibodies against PSA (anti-PSA) was evaluated using the differential pulse voltammetry technique. The limit of detection and limit of quantification of anti-PSA were determined as 1.35 nM and 4.08 nM for compact rod-shaped spherical ZnO nanostructures, and 2.36 nM and 7.15 nM for rod-shaped ZnO nanostructures, respectively.

Morphology formation during the nonisothermal thermally‐induced phase separation (TIPS) process

AbstractIn high‐viscosity polymer solutions and blends, temperature variations during the quench process of the thermally‐induced phase separation (TIPS) influence the dynamics and thermodynamics of phase separation. Hence, this study aims to investigate the impact of temperature variations on the morphology formation during the TIPS process. First, the influence of temporal temperature variations on phase separation is investigated by coupling a transient heat conduction model and the Cahn–Hilliard equation, and the results are compared with the isothermal phase separation process. Next, the morphology formation during phase separation is inspected by applying quench from two opposite sides of the sample to the same and different temperatures through coupling the Fourier heat transfer equation and the Cahn–Hilliard equation. The influence of the enthalpy of demixing on the morphology formation and the competition between the heat and mass transfer is also evaluated. It is confirmed that temporal variations of temperature alone have a significant impact on the morphology formation during the TIPS process. In addition, quenching the system to the same and different temperatures both leads to anisotropic morphology formation, which is affected by the quench rate, quench temperature, solution viscosity, and enthalpy of demixing. Upon applying different quench temperatures from opposite sides, two different types of morphologies and droplet sizes were formed as a result of the difference in the cooling rates between the two sides. Employing the enthalpy of demixing during phase separation induced a shallow quench effect on the deep quench side due to the fact that the heat moved toward the lowest temperature in the system, which led to the formation of a distinctive structure.

Magneto-plasticity in micro-cutting of single-crystal copper

• Magneto-plasticity can be induced by a weak magnetic field in micro-cutting. • Cutting force, chip and machined surface are affected by magneto-plasticity. • Magneto-plasticity shows anisotropy with magnetic field direction. • Directional dislocation flow results in anisotropic magneto-plasticity. The plasticity of metals can be significantly affected by the application of a magnetic field, otherwise known as the magneto-plastic effect. This paper investigates the magneto-plastic effect in the micro-cutting of a non-magnetic ductile material, single-crystal copper, under a weak magnetic field and reports the influence of the phenomenon on the cutting forces and machined surface quality. A softening effect was observed from the large reduction in cutting forces from 3.2 N to 1.5 N under the magnetic field. As compared to the magnetic field intensity and polarity, the variation in magnetic field orientations with respect to the cutting direction exhibited a stronger influence on the cutting force, chip morphology, machined surface texture, subsurface microstructure, surface roughness, and machined surface microhardness of the copper sample. An analytical model was developed based on the geometry of the cutting chips to correlate the orientation-dependent influence of the magnetic field on the cutting forces. On the surface quality, excessive folds with four different types of morphology produced under magnetic-free cutting were suppressed after applying the magnetic field with the most significant improvement achieved with the 90° magnetic field direction. The magnetic-assisted changes in machined surface morphology also led to the reduction in machined surface roughness and microhardness. The optimistic micro-cutting outcomes in this work establish a greater understanding of the magneto-plastic effect and demonstrate the applicability of magneto-plasticity in ultraprecision manufacturing.

Unusual flat and extended morphology of intercalated Cu under MoS2

A general method was developed to intercalate metals under layered materials through a controlled density of sputtered defects. The method has already been applied to study a range of metals intercalated under graphite, and different types of morphologies were realized. In the current work, we extend the method to the study of intercalation under ${\mathrm{MoS}}_{2}$, noting that work on this system is rather limited. We use Cu as the prototype metal for comparison with Cu intercalation under graphite. Although the growth conditions needed for intercalation under graphite and ${\mathrm{MoS}}_{2}$ are similar, the type of intercalated phases is very different. Each Cu island that nucleates on top of ${\mathrm{MoS}}_{2}$ during Cu deposition provides material that is transferred below ${\mathrm{MoS}}_{2}$ through sputtered defects under the island base; this transfer results in a uniform intercalated Cu ``carpet'' morphology that extends over the mesoscale. On the contrary, Cu intercalation under graphite results in well separated, compact islands formed by monomer detachment from small Cu islands on top and transfer below through defects far from the islands. The structural techniques (scanning electron microscopy and atomic force microscopy) and spectroscopic techniques (x-ray photoelectron spectroscopy and energy-dispersive spectroscopy) are used for the characterization of the intercalated Cu layer.

Nanostructured Electrospun Polycaprolactone-Propolis Mats Composed of Different Morphologies for Potential Use in Wound Healing.

This study aimed to investigate different types of morphologies obtained using the electrospinning process to produce a material that enables wound healing while performing a controlled release. Using benign solvents, the authors prepared and characterised electrospun polycaprolactone mats loaded with propolis, a popular extract in traditional medicine with potential for skin repair. Different morphologies were obtained from distinct storage periods of the solution before electrospinning to investigate the effect of PCL hydrolysis (average diameters of fibres and beads: 159.2–280.5 nm and 1.9–5.6 μm, respectively). Phytochemical and FTIR analyses of the extract confirmed propolis composition. GPC and viscosity analyses showed a decrease in polymer molecular weight over the storage period (about a 70% reduction over 14 days) and confirmed that it was responsible for the nanostructure diversity. Moreover, propolis acted as a lubricant agent, affecting the spun solutions’ viscosity and the thermal properties and hydrophilicity of the mats. All samples were within the value range of the water vapour transpiration rate of the commercial products (1263.08 to 2179.84 g/m2·day). Even though the presence of beads did not affect the propolis release pattern, an in vitro wound-healing assay showed that propolis-loaded mats composed of beaded fibres increased the cell migration process. Thus, these films could present the potential for use in wound dressing applications.

Flares in gamma-ray burst X-ray afterglows as prompt emission from slightly misaligned structured jets

ABSTRACT We develop a model to explain the flaring activity in gamma-ray burst X-ray afterglows within the framework of slightly misaligned observers to structured jets. We suggest that flares could be the manifestation of prompt dissipation within the core of the jet, appearing to a misaligned observer in the X-ray band because of less favourable Doppler boosting. These flares appear during the afterglow phase because of core–observer light travel delays. In this picture, the prompt emission recorded by this observer comes from material along their line of sight, in the lateral structure of the jet, outside the jet’s core. We start by laying down the basic analytical framework to determine the flares characteristics as a function of those of the gamma-ray pulse an aligned observer would see. We show that there is viable parameter space to explain flares with typical observing times and luminosities. We then analytically explore this model, showing that it naturally produces flares with small aspect ratios, as observed. We perform fits of our model to two Swift/XRT flares representing two different types of morphology, to show that our model can capture both. The ejection time of the core jet material responsible of the flare is a critical parameter. While it always remains small compared to the observed time of the flare, confirming that our model does not require very late central engine activity, late ejection times are strongly favoured, sometimes larger than the observed duration of the parent gamma-ray burst’s prompt emission as measured by T90.

Morphological Difficulties in People with Developmental Language Disorder.

Background: One of the linguistic features of people with Developmental Language Disorder (DLD) is found in the use of different types of morphology. People with DLD have serious difficulties in the use of grammatical morphology, and some studies suggest that this factor could constitute a clinical marker of the disorder. The goal of this research was to discover the distinctive characteristics of the different morphological subareas in people with DLD. Methods: The sample consisted of 90 children and adolescents between 6 and 15 years old, of which 47 were diagnosed with DLD and the remaining 43 were in the Typical Development (TD) group. The two groups were matched in chronological age. The assessment instrument used was the morphology scale of the BLOC-C test, which includes 19 different subareas of morphology, among which are inflectional and verbal morphology. Results: The results have shown that people with DLD perform at a lower level than the TD group in all morphology subareas, as well as in the mean and percentile obtained. Conclusions: These data have led us to explore explanations based on several hypotheses and to confirm the research outlining the explicit morphological difficulties in people with DLD.

Adaptive processing for noise attenuation in laser speckle contrast imaging

Background and Objective: Blood vessel visualization is an essential task to treat and evaluate diseases such as port-wine stain. Laser Speckle Contrast Imaging (LSCI) have applications in the analysis of the microvasculature. However, it is often limited to superficial depths because the tissue among skin and microvasculature introduces noise in the image. To analyze microvasculature, traditional LSCI methods compute a Contrast Image (CI) by using a shifting window of fixed size and shape, which is inadequate in images with structures different types of morphologies in it, as happens in LSCI. This work aims to reduce the noise in the CIs to improve the visualization of blood vessels at high depths (> 300 μ m). Methods: The proposed method processes the CIs with analysis windows that change their size and shape for each pixel to compute the contrast representation with pixels more representatives to the region. Results: We performed experiments varying the depth of the blood vessels, the number of frames required to compute the representation, and the blood flow in the blood vessel. We looked for an improvement in the Contrast to Noise Ratio (CNR) in the periphery of the blood vessels using an analysis of variance. Finding that the adaptive processing of the contrast images allows a significant noise attenuation, translated into a better visualization of blood vessels. An average CNR of 2.62 ± 1 and 5.26 ± 1.7 was reached for in-vitro and in-vivo tests respectively, which is higher in comparison with traditional LSCI approaches. Conclusions: The results, backed by the measured CNR, obtained a noise reduction in the CIs, this means a better temporal and spatial resolution. The proposed awK method can obtain an image with better quality than the state-of-the-art methods using fewer frames.

Trypsin Induced Degradation of Amyloid Fibrils.

Proteolytic enzymes are known to be involved in the formation and degradation of various monomeric proteins, but the effect of proteases on the ordered protein aggregates, amyloid fibrils, which are considered to be extremely stable, remains poorly understood. In this work we study resistance to proteolytic degradation of lysozyme amyloid fibrils with two different types of morphology and beta-2-microglobulun amyloids. We showed that the proteolytic enzyme of the pancreas, trypsin, induced degradation of amyloid fibrils, and the mechanism of this process was qualitatively the same for all investigated amyloids. At the same time, we found a dependence of efficiency and rate of fibril degradation on the structure of the amyloid-forming protein as well as on the morphology and clustering of amyloid fibrils. It was assumed that the discovered relationship between fibrils structure and the efficiency of their degradation by trypsin can become the basis of a new express method for the analysis of amyloids polymorphism. Unexpectedly lower resistance of both types of lysozyme amyloids to trypsin exposure compared to the native monomeric protein (which is not susceptible to hydrolysis) was attributed to the higher availability of cleavage sites in studied fibrils. Another intriguing result of the work is that the cytotoxicity of amyloids treated with trypsin was not only failing to decline, but even increasing in the case of beta-2-microglobulin fibrils.

Red-emitting CaWO4:Eu3+,Tm3+ phosphor for solid-state lighting: Luminescent properties and morphology evolution

CaWO4:xEu3+,yTm3+ crystals were obtained by facile synthesis at low temperature by the microwave-assisted hydrothermal method (MAH). The phase formation, morphology, luminescent properties and energy transfer were investigated. The X-ray diffraction (XRD) results show the formation of a scheelite-like tetragonal structure without the presence of secondary phases. The growth mechanism of hierarchical microstructures based on self-assembly and Ostwald-ripening processes was evaluated, obtaining different types of morphologies. The luminescence spectra of CaWO4:Eu3+,Tm3+ at 325 nm excitation show the predominance of red emission at the 5D0 → 7F2 (Eu3+) transition at 624 nm. This feature signals dominant behavior of the electric dipole type. The presence of Tm3+ is notably evident in the absorption spectra by the related excitation transitions: 3H6 → 1G4, 3H6 → 3F3 and 3H6 → 3H4. Color parameters are discussed to characterize CaWO4:Eu3+,Tm3+ emission. The study of the emission spectrum as a function of the concentration of Eu3+ (x mol%) and Tm3+ (y mol%) indicates that the CaWO4:Eu3+,Tm3+ phosphors show stronger red emission intensity and exhibit the CIE value of x = 0.63 and y = 0.35. The photoluminescence results show 97% high color purity for CaWO4:4 mol%Eu3+, a high CRI (92%) and a low CCT of 1085 K. These results demonstrate that the CaWO4:Eu3+,Tm3+ red phosphors are promising as color converters for application in white light-emitting diodes and display devices.

Photo sensitizing and electrochemical performance analysis of mixed natural dye and nanostructured ZnO based DSSC

The paper highlights the enactment of the natural dyes, like purple cabbage, spinach, turmeric and their mixture as a photo-sensitizer, with nanostructured zinc oxide (ZnO) as a photo-anode, based dye-sensitized solar cell (DSSC). The field emission scanning electron microscopic image of ZnO, prepared by chemical bath deposition process, proclaims two different types of morphology, nano-wire and nano-plate shape. The photo sensitizing properties of the natural dyes and their mixed part are explored through FTIR spectra and UV-vis light absorbance characteristics. The FTIR spectra explore the presence of different anchoring chemical groups which confirm the strong anchoring bond with ZnO and enhancement of electron mobility. The diffused reflectance spectra (DRS) of dye-loaded ZnO films incisive the absorption of dye on the mesoporous ZnO surface. The relative energy band positions of individual and mixed dye, yield stable execution of the cell that has been performed through the cyclic voltammeter. The driving force energy requirement for effortless transport of electron from the mixed dye to the conduction band of ZnO is revealed lowers (0.34 eV) as compared to individual dyes. Electrochemical impedance spectroscopy (EIS) analysis has been executed to find the charge transfer resistance, total bulk resistance, recombination loss through Nyquist plots and Bode plots. These characteristics pretense as the mixed dye has an eminent rate of electron transportation and lower recombination loss with longer electron lifetime. The photon to electrical power conversion efficiencies of purple cabbage, spinach, turmeric and their mix dyes are explored as 0.1015%, 0.1312%, 0.3045%, and 0.602%, respectively under same simulated light condition. The mixed dye reveals the stable performance of the cell with the highest conversion efficiency due to the absorption of an extensive range of the solar spectrum and well-suited electrochemical responses.

Topological layered nanostructures with controlled functional characteristics induced by laser radiation on a solid surface

Models of the formation of roughnesses on the surface of materials and the movement of distributed flows in their presence are considered, which ultimately determines the functional properties of such topological materials of different compositions induced by laser radiation. The paper also presents simulation of crystallization of complex structures from a melt with an analysis of the morphology of the resulting crystalline structures, and shows examples of the occurrence of fractal dendritic formations. Different types of morphology are induced depending on the energy of the laser radiation and the duration of the heating; determining the final state of objects with the desired functional and structural characteristics. Using the methods of cellular automata, the models were obtained for both the distribution of crystallization centers and the growth of an individual cluster under the influence of diffusion mechanisms. The relationship between the resulting morphology and the modified parameters of the models used is analyzed.

Chemical Ordering in Bi1–xSbx Nanostructures: Alloy, Janus, or Core–Shell

Bismuth antimonide is an important material in nanoelectronics as a topological insulator and thermoelectric material. However, some of its thermal properties are still mostly unknown at the nanoscale. The goal of this paper is to fill this gap in knowledge and provide the phase diagram of bismuth antimonide at small sizes for different types of morphologies like the sphere, rod, wire, and film. By using nanothermodynamics concepts, a surface segregation index is newly defined to easily determine which chemical element segregates preferentially to the surface. In bismuth antimonide nanostructures, bismuth is predicted to be the pnictogen element segregating naturally to the surface of the alloy. Moreover, the chemical ordering (alloy, core–shell, and Janus) of bismuth antimonide is provided as a function of size, temperature, and composition. Finally, the miscible region where bismuth and antimony forms a randomly mixed alloy is found to shrink considerably when the size of the nanostructure is reduced, whatever the considered shape is. This confirms that miscibility is not enhanced at the nanoscale but phase separation is.

The influence by substrate morphology on the Rashba band splitting in graphene

The influence of substrate morphology on the Rashba band splitting at the Dirac point of graphene, has been theoretically investigated. More specifically, the possibility for this splitting to be caused by spin–orbit coupling (with the heavy metal substrate) was of a special interest to study. The model system consisted of a 4H-SiC (0 0 0 1)/graphene interface, with an intercalated metal layer (Ag and Au, respectively). These intercalating metal layers were built with two different types of morphologies; either flat or buckled (with different buckling positions). The results show that depending on the position of the buckled metal atom, the size of the bandgap and band splitting (at the Dirac point of graphene) will either increase (or decrease). Moreover, the enlargement of the buckling size was also shown to affect the electronic properties of graphene (i.e., by increasing the bandgap). The sizes of the bandgaps and band splitting for the different intercalating metals (Ag and Au), were also found to be different. Spin-projected band structures was also implemented in the present study, with the purpose to show the spin-texture of graphene. It was thereby shown that the spins pined to the x and y spin components for most of the cases.

Study on the effect of methanol on the morphology and optical properties of ZnO

Materials property is often associated with their structure and morphology. ZnO has shown many different types of morphologies that can be achieved by tuning the growth conditions. In this study, methanol was used to control the morphology of ZnO synthesized by a hydrothermal method. By changing the methanol concentration in the growth solution, ZnO nanosheets, nanorods, and microspheres were obtained and studied by scanning electron microscopy, transmission microscopy, x-ray diffraction, x-ray photoemission spectroscopy, UV–vis spectrophotometer and Photoluminescence spectrometer. The concentration of methanol in the growth solution was found to play a critical role in the formation of ZnO structures. The possible growth mechanism was discussed by considering the production of NO3 ions with the addition of methanol and their impact on ZnO growth through preferential surface adsorption on different facets.

Off-Eutectic Au–Ge Die-Attach—Microstructure, Mechanical Strength, and Electrical Resistivity

In this paper, off-eutectic Au–Ge joints were formed between Si substrates to investigate their high-temperature compatibility. High-quality joints made with small bond pressure, 53 kPa, were fabricated. The joints comprised three different types of morphologies: 1) a layered structure of Au/Au–Ge/Au; 2) a layered structure of Au/Au–Ge/Au where some sections of the central Au–Ge band have been replaced by an Au section that extended across the entire section; and 3) a roughly homogenous Au layer comprising the primary $\alpha $ phase. The average Ge concentration was 10 ± 2 at%. Joints formed with a higher bond line pressure, 7.6 MPa, were of a reduced quality with voids and cracks at the original bond line. Annealing at 400 °C for 1000 h transformed the microstructure into an Au–Ge–Si compound with Au precipitates. The shear strength of the fabricated joints was found to be at least 50 MPa, and the fracture mode was an adhesive fracture between the adhesion layer and the die or substrate. Heated dies detached from the substrates at 460 °C, i.e., more than 100 °C above the eutectic melting point of the binary Au–Ge system. Electrical resistivity measurements confirmed a melting process at the eutectic melting point by an abrupt increase in resistivity.

(FeCO3) Cementation by Carbonation of Iron Rich Systems

The paper reports the observation that siderite (FeCO3 mineral) cementation occurs when compacted Fe-powder (10 µm in this study) is subjected to aqueous carbonation. It is further shown that the siderite contents of the reaction products vary based on the temperature and the CO2-pressure conditions under which they are carbonated. Using SEM-SE observations, two different types of morphologies of siderite crystals are observed based on the temperature are which the aqueous carbonation of iron is performed. The XRD-Rietveld observations and the SEM-SE observations are combined to infer that dendritic Fe-oxide crystals are formed away from the Fe surfaces, and that the siderite crystals grow as scales at the carbonating Fe surfaces. The concurrence of the variation in the siderite content and compressive strength is observed based on XRD-Rietveld analysis. The results of XRD-Rietveld analysis and MIP are combined to show that pore filling and refinement may not be a suitable indicator of compressive strength in such systems.

Programming configurational changes in systems of functionalised polymers using reversible intramolecular linkages

ABSTRACTWe study polymers functionalised by complexes forming intramolecular linkages. Simulations of chains forming reversible linkages are difficult due to entropic barriers that hamper the sampling of different connectivity states specified by the list of pairs of reacted complexes. We address this problem by devising Monte Carlo (MC) moves that change the connectivity state of the system by regrowing parts of the chain while simultaneously reacting bond-forming complexes. Along with moves that link/unlink pairs of complexes, we develop two types of bond-exchange moves. We use these algorithms to study self-assembly of single chain polymeric nanoparticles. When considering monofunctional precursors, we find branched and linear nanoparticle morphologies dominated by long and short intramolecular loops, respectively, along with hierarchical structures in which complexes belonging to different loops are cross-linked. In the strong association limit, equilibrium structures are only reached when using bond-exchange MC moves. We also consider bifunctional precursors in which two different types of complexes decorate the two halves of the chain. We find different types of morphologies featuring different amounts of linkages between complexes of different types. Such findings corroborate our method as a valuable tool to design and predict self-assembly of functional polymers.