Effect Of Sharp Edges Research Articles

Multifunctional MXene-doped photothermal microneedles for drug-resistant bacteria-infected wound healing.

Skin injuries and drug-resistant bacterial infections pose serious challenges to human health. It is essential to establish a novel multifunctional platform with good anti-infection and wound-healing abilities. In this study, a new MXene-doped composite microneedle (MN) patch with excellent mechanical strength and photothermal antibacterial and ROS removal properties has been developed for infected wound healing. When the MN tips carrying the MXene nanosheets are inserted into the cuticle of the skin, they will quickly dissolve and subsequently release the nanomaterials into the subcutaneous infection area. Under 808 nm NIR irradiation, the MXene, as a "nano-thermal knife", sterilizes and inhibits bacterial growth through synergistic effects of sharp edges and photothermal antibacterial activity. Furthermore, ROS caused by injury and infection can be cleared by MXene-doped MNs to avoid excessive inflammatory responses. Based on the synergistic antibacterial and antioxidant strategy, the MXene-doped MNs have demonstrated excellent wound-healing properties in an MRSA-infected wound model, such as promoting re-epithelialization, collagen deposition, and angiogenesis and inhibiting the expression of pro-inflammatory factors. Therefore, the multifunctional MXene-doped MN patches provide an excellent alternative for clinical drug-resistant bacteria-infected wound management.

Numerical simulation of square shaped particle sedimentation

Direct numerical simulations of square particle sedimentation in a viscous incompressible fluid are presented to examine the effects of sharp edges for various particle-to-fluid density ratios and different initial inclination angles. The settling process exhibits four different motion regimes; non-oscillatory, non-uniform centered oscillatory, uniform off-centered oscillatory, and non-uniform off-centered (irregular) oscillatory. At moderate density ratios, we observe that the rotational motion of settling square particle varies with the initial inclination angle. We employ Dynamic Time Warping and Fast Fourier Transform to analyze translational and angular velocities. Oscillating systems are described using phase-space plots, and a chaotic phenomenon is observed at a higher density ratio.

Antibacterial properties of graphene and its derivatives

The work presents a literature review on the use of graphene and its derivatives as the potential protection against bacterial microflora. Addressed issues relate to an attempt to explain the mechanisms of impact of graphene and its derivatives: graphene oxide (GO) and reduced graphene oxide (rGO) on the bacterial cells. Interaction of graphene materials (G, GO, rGO) with Gram(+) and Gram(-) were compared with regard to the concentration of the preparations, the nature of the culture medium and surface of graphene deposition. Issues related to the development of reactive oxygen species (ROS) were discussed, the effect of sharp edges of GM’s (nano-knife), biofilm formation and the potential application of graphene in nanomedicine. Keywords: biomedicine, graphene, graphene oxide antibacterial effect, biofilm

Antibacterial properties of nanoporous graphene oxide/cobalt metal organic framework.

Metal-organic framework (MOF) based graphene oxide (GO) recently merits of attention because of the relative correspondence of GO with metal ions and organic binding linkers. Furthermore, introducing the GO to the Co-MOF to make a new nanoporous hybrid have are improved the selectivity and stability of the Co-MOF. Here the graphene oxide/cobalt metal organic framework (GO/Co-MOF) was synthesized by a solvothermal process using cobalt salt and terephthalic acid and used for biocidal activity, against the growth of the Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. X-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy were confirmed the successful synthesize of metal organic framework and incorporation of Co-MOF in to GO sheets. Scanning electron microscopy was showed the cornflower structure of GO/Co-MOF, and transmission electron microscopy was confirmed, the Co-MOF are decorated on GO. Cytotoxicity study of GO/Co-MOF using 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium bromide (MTT) cell viability assay showed the biocompatibility to human fibroblasts cell over 72 h. The growth inhibition of the Escherichia coli and Staphylococcus aureus bacteria are reached over 99% for bacteria concentration of 100 μg/mL. The excellent antibacterial activity of GO based Co-MOF is linked to synergistic effect of sharp edges of the GO sheets and the toxic effect of cobalt ions (Co2+) which are released from their surfaces. The GO/Co-MOF radical scavenging assay was measured using 1,1-diphenyl-2-picrylhydrazyl (DPPH) antioxidant assay for samples incubated with cells which confirmed the minimum radicals' toxicity on bacteria. This novel graphene oxide based MOF with its intrinsic superior porous structure, highly active metal coordination, and commercial linker, is an excellent promising candidate to use in biological and pharmaceutical applications as high potential sustained bactericidal materials.

Effect of roughness and shape factor on flotation characteristics of glass beads

Abstract The effect of surface roughness and shape factor on behavior of particles in flotation has been investigated. Surface roughness of various degrees was applied on spherical glass beads of −150 +106 μm by means of acid etching. The same procedure was also performed on ground glass beads of the same size interval with different shape factors. The effect of these variations on surface morphology of particles was investigated in terms of flotation recovery, contact angle, and bubble-particle attachment. An Atomic Force Microscope (AFM) was used for surface roughness characterizations and a correction methodology on roughness measurements of spherical particles is proposed. A digital image analyzer was used for shape factor characterizations. It is shown that increase in surface roughness improves the flotation recovery, contact angle, and bubble attachment. Shape factor, however, was found to be more predominant in flotation and bubble attachment. This is attributed to the effect of sharp edges of ground particles which triggers the film rupture process and shortens the attachment time.

Implementation of Shading Techniques Based on OpenGL

Shading can smooth the appearance of polygons by reducing the effects of sharp edges, which makes drawn graphics more realistic. Consider factors related to the object surface brightness, analyze and compare several shading algorithms, focus on presenting spherical linear interpolation of the Phong shading, and use OpenGL to realize the procedures and effect diagrams of Flat shading and Gouraud shading in VC + + environment.

Investigation on the effect of sharp phantom edges on point dose measurement during patient-specific dosimetry with Rapid Arc

The objective of this work was to investigate and quantify the effect of sharp edges of the phantom on the point dose measurement during patient-specific dosimetry with Rapid Arc (RA). Ten patients with carcinoma of prostate were randomly selected for this dosimetric study. Rapid Arc plans were generated with 6 MV X-rays in the Eclipse (v 8.6.14) with single arc (clockwise). Dosimetry verification plans were generated for two phantoms (cylindrical and rectangular). The cylindrical phantom was solid water (diameter 34 cm) and the rectangular phantom was a water phantom (25 cm × 25 cm × 10 cm). These phantoms were pre-scanned in computed tomography (CT) machine with cylindrical ionization chamber (FC65) in place. The plans were delivered with Novalis Tx linear accelerator with 6 MV X-rays for both the phantoms separately. The measured dose was compared with the planned dose for both the phantoms. Mean percentage deviation between measured and planned doses was found to be 4.19 (SD 0.82) and 3.63 (SD 0.89) for cylindrical and rectangular phantoms, respectively. No significant dosimetric variation was found due to the geometry (sharp edges) of the phantom. The sharp edges of the phantom do not perturb the patient specific Rapid Arc dosimetry significantly.

Manipulating and probing the growth of plasmonic nanoparticle arrays using light

Highly ordered self-assembled silver nanoparticle (NP) arrays have been produced by glancing angle deposition on faceted c-plane Al2O3 templates. The NP shape can be tuned by changing the substrate temperature during deposition. Reflectance anisotropy spectroscopy has been used to monitor the plasmonic evolution of the sample during the growth. The structures showed a strong dichroic response related to NP anisotropy and dipolar coupling. Furthermore, multipolar resonances due to sharp edge effects between NP and substrate were observed. Analytical and numerical methods have been used to explain the results and extract semi-quantitative information on the morphology of the NPs. The results provide insights on the growth mechanisms by the glancing angle deposition. Finally, it has been shown that the NP morphology can be manipulated by a simple illumination of the surface with an intense light source, inducing changes in the optical response. This opens up new possibilities for engineering plasmonic structure over large active areas.

Adhesion of Particles with Sharp Edges to Air–Liquid Interfaces

In order to study the effect of sharp edges on solid particle adhesion to air-liquid interfaces, spherical colloidal probes were modified with a circumferential cut by focused ion beam milling. The interaction of the modified particles with water drops and bubbles was studied using the colloidal probe technique. When the modified particles were brought into contact with air-liquid interfaces, the contact line was pinned at the edge of the cut. Contact hysteresis between the approach and retraction components of the measured force curves was eliminated. The contact angle at the edge takes a range of values within the limits defined by the Gibbs inequality. These limits determine the adhesion force. As such, the adhesion force is a function of the particle wettability and edge geometry.

Shape Control of Local Parameter Adjustable Five Rational Transect and Application

In order to enlarge the image after low-resolution images can still be rich in detail, the effect of sharp edges, this article constructs a rational quintic spline interpolation, and applied to image interpolation, due to the interpolation function has five Local shape control performance parameters, making the image zoom in or out of, according to the need for control. Experimental results show that the interpolation functions are constructed five effective and robust.

Shape Control of Local Parameter Adjustable Five Rational Transect and Application

In order to enlarge the image after low-resolution images can still be rich in detail, the effect of sharp edges, this article constructs a rational quintic spline interpolation, and applied to image interpolation, due to the interpolation function has five Local shape control performance parameters, making the image zoom in or out of, according to the need for control. Experimental results show that the interpolation functions are constructed five effective and robust.

Water droplet properties on periodically structured superhydrophobic surfaces: a lattice Boltzmann approach to multiphase flows with high water/air density ratio

Surface roughness affects the contact angle (CA) due to the increased area of solid–liquid interface and due to the effect of sharp edges of rough surfaces. Roughness may also lead to another non-wetting regime, by forming a composite solid–liquid–air interface between the water and the textured surface; this composite interface exhibits strong water repellency due to the various pockets of air entrapped between the surface textures. The contact between water and a hydrophobic textured surface leads to one of these two regimes depending on the thermodynamics stability of the regimes. In this study, the projection method of lattice Boltzmann method is used to analyze the large density difference at the air and water interface. The method is applied to simulate two-phase flows with the density ratio of up to 1,000. A numerical model is presented to provide a relationship between roughness and CA, which is used to develop optimized texture topography and create a biomimetic superhydrophobic surface. The numerical models encompass the effects of contact area, solid–liquid–gas composite interface and shape edges. The models are reused to analyze different possible roughness distributions and to calculate the effect of the cross-sectional area of pillars, including rectangular, triangular, cross, and pyramidal pillars. The energy barrier is investigated to predict the position of the transition between the Cassie and Wenzel regime observed for each roughness parameter as well as a theoretical free surface energy model.

Roughness optimization for biomimetic superhydrophobic surfaces

For non-wetting liquids the contact angle with a rough surface is greater than with a flat surface and may approach 180°, as reported for leaves of water-repellent plants, such as lotus. Roughness affects the contact angle due to the increased area of solid–liquid interface and due to the effect of sharp edges of rough surfaces. High roughness may lead to composite solid–liquid–air interface, which may be either stable or unstable. A comprehensive analytical model is proposed to provide a relationship between local roughness and contact angle, which is used to develop roughness distribution and to create biomimetic superhydrophobic surfaces. Various roughness distributions are considered, including periodic and surfaces with rectangular, hemispherically topped cylindrical, conical and pyramidal asperities and the random Gaussian height distribution. Verification of the model is conducted using experimental data for the contact angle of water droplet on a lotus leaf surface. For two solid bodies in contact, for wetting liquids, wetting leads to the meniscus force, which affects friction. Dependence of the meniscus force on roughness, previously ignored, is considered in the paper and it is found that with increasing roughness meniscus force can grow due to scale effect.

Edge effects on ant community structure and species richness in an agricultural landscape

The effect of sharp edges between three different types of land use on the species richness and structure of ant communities was examined in an agricultural landscape within Central Hesse, Germany. Species richness and nest densities of ants at the centres and the edges of meadows, crop fields, and fallow land were recorded by hand sampling during 1997 and 1998. Edges between different land-use types did not increase ant species richness at the landscape scale, nor were they unique habitats for a specialised ant fauna. Nonetheless, most species shared ‘ecotonal effects’ in the way that their relative abundance either decreased (e.g. Myrmica scabrinodis) or increased (e.g. Lasius niger, Lasius flavus) at the edges, resulting in different community structure between edges and centres of the land-use types. This was influenced by two major factors: (i) the boundary contrast between the neighbouring habitats (i.e. in terms of disturbance caused by agricultural practices), and (ii) the response of different species to changing abiotic conditions. High nest densities of aggressive species with large colonies occurred along edges. We hypothesise that this can significantly reduce edge permeability for surface-dwelling arthropods.

Three-Dimensional Vortex Simulation of Time Dependent Incompressible Internal Viscous Flows

A hybrid random vortex-boundary element method is developed for the solution of time-dependent incompressible three-dimensional internal flow problems. The numerical scheme is grid-free within the flow domain and is based on a combination of the Lagrangian vortex method to capture the convection and stretch of the vortical field, the random walk method to describe the diffusion process, and the boundary element method to superimpose a potential flow on the vortical field such that the normal flux boundary condition is satisfied. The no-slip boundary condition is satisfied by generating vorticity tiles on solid boundaries, which are subsequently diffused and convected into the flow interior. Additionally, a boundary condition is devised for the application of fully developed flow properties at the exit plane. In this paper, the formulation and the numerical scheme are presented, followed by a parametric study of the accuracy of the method using the model problem of the flow in a duct with square cross section at Re= 100. We show that the method converges to the analytical solution of the problem as the resolution of the time integration and the discretization are improved, and we discuss the impact of each resolution parameter on the accuracy. In addition, selected results from the simulation of an impulsively started flow over a cube at Re= 100 are presented. We use the results of this test case to demonstrate that the method captures the effect of sharp edges, parallel and normal to the streamwise flow direction, on the flow dynamics.

The effect of edges on the distribution of arboreal marsupials in the ash forests of the Victorian Central Highlands

Summary Effects of sharp edges induced by timber harvesting and diffuse edges induced by wildfire on the distribution of arboreal marsupials, were investigated by spotlight surveys in the ash forests of the Victorian Central Highlands. Edges were examined between three age-classes of forest (165+, 55-year- old fire regrowth and logging regrowth 5–20 years after loggging), with sites at 200m intervals up to 900m from the edge. The edge itself appeared to have little effect on the distribution and abundance of the arboreal marsupials recorded in this study; the distribution of species appeared related to features of the adjoining forest patches of differing age including their structure, and the distribution of food resources and hollow-bearing trees. Greater Gliders occured in all age- classes but were most common in old forest with numbers declining across edges and into 55-year-old fire regrowth. This trend was correlated with the distribution of hollow- bearing trees, particularly live hollow-bearing tr...

A new analytical approach for radiation problem from finite cylindrical piezoceramic shell

The objective of this paper is to present a complete analytical solution for a finite piezoelectric cylinder radiation problem. Three aspects of the problem are discussed. (1) Development of a theory of thin piezoceramic shells with hypotheses for electric field components that are equivalent to the classical Love’s mechanical ones. (2) Explanation of a new analytical approach to solve a coupled elastic–electric–fluid interaction problem. The exact solution for the acoustic potential function is given in terms of an infinite series of partial solutions of the Helmholtz equation in cylindrical and spherical coordinate systems. The associated coefficients are the solution of an infinite linear system. A new approach to truncation of this system which takes into account the sharp edge effects, is developed. An estimation of the calculation accuracy of the method is presented. (3) Numerical implementation of the analytical solution for different values of key parameters gives a ground to elucidate a complex exchange of energy between electric generator, elastic structure, and surrounding fluid. Modification of eigenforms of the shell due to radiation in water is described.

The teapot effect: sheet-forming flows with deflection, wetting and hysteresis

The flow of a two-dimensional viscous film falling from the edge of an inclined plane exhibits a distinctive set of phenomena which, in various combinations, have been referred to as the teapot effect. This paper makes plain that three basic mechanisms are at the root of these phenomena: deflection of the liquid sheet by hydrodynamic forces, contact-angle hysteresis, and multiple steady states that give rise to a purely hydrodynamic hysteresis. The evidence is drawn from Galerkin/finite-element analysis of the Navier-Stokes system, matched to a one-dimensional asymptotic approximation of the sheet flow downstream, and is corroborated experimentally by flow visualization and measurements of free-surface profiles and contact line position. The results indicate that the Gibbs inequality condition quantifies the inhibiting effect of sharp edges on spreading of static contact lines, even in the presence of flow nearby. The branchings, turning points, and isolas of families of solutions in parameter space explain abrupt flow transitions observed experimentally, and illuminate the stability of predicted flow states.

Electrostatic, Thermal and Vapor Density Fields Surrounding Stationary Columnar Ice Crystals

Abstract Formulas suitable for calculating the electrostatic, temperature, and vapor density fields surrounding stationary columnar ice crystals are derived. Columnar ice crystals are approximated as circular cylinders of finite lengths. In this way the effects of sharp edges are taken into account. Results of electrostatic fields for some columnar ice crystals are shown. The potential distribution of a prolate spheroid is also determined and compared to that of a circular cylinder. The results show that the approximation of a columnar crystal by a prolate spheroid is inadequate. Formulas are also given to convert the electric fields into temperature and vapor density fields.

Relationship between junction radius and reverse leakage of silicide Schottky-barrier diodes

Unguarded Schottky-barrier diodes exhibit excessive leakage current in the reverse-current direction. A portion of this excess current has always been attributed to sharp-edge effects. In this paper, the sharp-edge-related excess reverse current is attributed to the additional barrier lowering that is due to the electric-field enhancement present near the diode edges. Mathematical relationships describing the effect of the edge radius on the I-V characteristics of unguarded diodes are developed. These relationships are then used to model an unguarded Schottky-barrier diode. The correlation between the junction radius and the diode characteristics was found to be strong in the reverse-current direction. In the foward direction, the diode characteristics were not greatly affected, and thus the large diode-quality factors of unguarded diodes cannot be attributed to the sharp-edge effect. A comparison is made between the experimental characteristics of Pd 2 Si/ nSi and VSi 2 /nSi diodes and those obtained from modeling.