Cylindrical Matrix Research Articles

Numerical analysis of tunable defect mode in cylindrical photonic crystals configuration

AbstractIn contrast to most of the previous publications that has addressed the dependency of the defect mode on temperature in planner one‐dimensional photonic crystal, we study this dependency in cylindrical photonic crystal taking into consideration both thermal‐optical and thermal expansion effects. Our analysis, based on the cylindrical transfer matrix, is conducted for both types of polarized electric and magnetic waves. Our structure is composed of arrays of cylindrical coaxial shells of TiO2 and Al2O3 with single defect layer. Numerical results show that the defect mode's wavelength can be effectively tuned, following a linear relation, by changing the temperature for both types of polarized waves. In addition, the peak transmittance is dependent on the number of periods and the starting inner radius. Moreover, decreasing the inner radius is associated with separation between the two polarizations.

Elastic behaviour of multiply coated fibre-reinforced composites: Simplification of the (n+1)-phase model and extension to imperfect interfaces

The elastic strain and stress fields in an n-layered transversely isotropic cylindrical inclusion surrounded or not by an infinite transversely isotropic cylindrical matrix and subjected to uniform conditions respectively at infinity or on the limit of the n-layered inclusion are derived in a simpler way than before by means of a recently introduced transfer matrix. The interface between the different phases can be perfect or imperfect. These fields are used to calculate the average strain and stress in each phase and in the n-layered inclusion. Thanks to this new transfer matrix the Generalized Self Consistent Scheme named (n+1)-phase model has been simplified and extended to the case of imperfect interfaces.

Impact of different surface treatment methods on bond strength between fiber post and composite core material

PurposeTo assess the impact of different surface treatments on the push-out bond strength between fiber post and a composite resin core material. Material and methodsSeventy-two glass-fiber posts were randomly assigned into six groups according to the method of surface treatment: Control (no treatment), silane, sandblasting, hydrofluoric acid, hydrogen peroxide, and hydrogen peroxide with sandblasting. Two posts from each group were inspected under a scanning electron microscope to assess the surface modifications and 10 posts were employed for the push-out test. Each post was placed vertically in the middle of a cylindrical putty matrix and a dual-cure composite resin material was applied for core build-up. Two discs of each specimen were cut using a low-speed diamond saw (total 120 discs). The push-out test was executed using a universal testing machine at a crosshead speed of 0.5 mm/min. Statistical analysis was performed using one-way ANOVA and Tukey’s test (p ≤ 0.05). The mode of failure of each disc was evaluated under SEM. ResultsThe sandblasting and hydrofluoric acid groups presented significantly higher bond strength than control and hydrogen peroxide groups. The hydrogen peroxide groups exhibited significantly the lowest bond strength of all groups. There was no significant difference between the control and silane groups. All groups showed predominantly adhesive failure except the hydrogen peroxide with sandblasting, where the cohesive failure of the post was predominant. ConclusionsSandblasting and hydrofluoric acid surface treatments demonstrated superior results to silane and hydrogen peroxide. The combined method of hydrogen peroxide and sandblasting could weaken the fiber post and lead to clinical fractures.

Strengthening bonding strength in NiTi SMA fiber-reinforced polymer composites through acid immersion and Nanosilica coating

Extensive applications of shape-memory alloy fiber-reinforced polymer composites are limited by the weak bonding conditions between alloy fibers and their surrounding matrix. In this work, we aim to investigate an effective means for elevating the interfacial bonding between nickel-titanium shape-memory alloy fibers and epoxy matrix by the combination of nitric acid immersion and nanosilica particles coating. Three experimental tests were carefully designed and conducted for verifying and validating the proposal. They include the uniaxial tensile test of chemically etched fibers, the pull-out test against a single fiber embedded inside a cylindrical epoxy matrix, and the three-point flexural test on fiber-reinforced polymer composites. Extensive parametric tests were performed in order to both qualify and quantify the effects of chemical etching, nanoparticle coating, and their combination. Experimental tests were followed a comprehensive analysis on both the mechanical behavior and the microscopic and macroscopic morphology of the specimens. Experimental results suggest the possibility of effectively elevating the interfacial bonding strength between nickel-titanium shape-memory alloy and epoxy matrix by the appropriate coupling of acid immersion and nanoparticle coating. Microscopical optimization mechanisms were also proposed and validated in terms of both intergranular and transgranular cracking along fiber/matrix interface subjected to shear loading.

Very Large Eddy Simulation of turbulent flow and heat transfer for single cylinder and cylindrical pin matrix

The study of turbulent flow and heat transfer around a cylinder and cylindrical pin matrix is important for turbine blade cooling. A newly developed VLES method is applied to investigate the unsteady flow and heat transfer mechanisms. DDES and unsteady RANS methods are also used in the simulations for comparisons. Two typical cases are selected, i.e. the flow around a single cylinder, and cylindrical pin matrix of wall-bounded 8 × 8 round pins, with Re = 10000. The results show that the VLES predictions agree well with the experiments for both the flow velocities and heat transfer Nusselt numbers for the two cases, which are even better than the DDES and RANS results. The VLES method gives satisfactory predictions of mean endwall Nusselt number of the complex pin matrix, which is within 15% difference from the experiments. The unsteady three-dimensional vortex characteristics play an important role for the heat transfer, especially in the pin matrix due to complex pin disturbance and wall confinement. Accurate representation of the vortex structures is the key for good heat transfer prediction. The results demonstrate the reliability and accuracy of the present VLES method for complex turbulent convection heat transfer of industrial relevance.

Effect of nanomaterial incorporation on the mechanical and microbiological properties of dental porcelain

Statement of problemDental porcelain restorations are subject to biological failures related to secondary caries and periodontal disease leading to prosthesis replacement. PurposeThe purpose of this in vitro study was to explore the microbiological and mechanical properties of dental porcelain incorporated with different percentages of silver vanadate (β-AgVO3) through microbiological analysis, roughness tests, and the Vickers microhardness test. Material and methodsIPS InLine porcelain specimens were made by using a cylindrical Teflon matrix in the dimensions of 8×2 mm. For the control group, the porcelain was manipulated according to the manufacturer's instructions. The groups incorporating the nanomaterial were prepared with 2.5%, 5%, and 10% of β-AgVO3, which was added proportionally by mass to the porcelain powder. In vitro microbiologic analysis, roughness tests, and the Vickers microhardness test were performed. ResultsAgainst Streptococcus mutans, the control group showed no inhibition halo (0 mm). All groups with AgVO3 showed a zone of inhibition, the highest for the group with 10% (30 mm) and then the groups with 2.5% (9 mm) and 5% (17 mm). For Vickers microhardness, no statistically significant difference (P<.05) was observed between the evaluated groups. The group with 10% of AgVO3 had the highest mean roughness and was statistically different (P<.001) from the other groups. ConclusionsAdding β-AgVO3 to dental porcelain demonstrated antimicrobial effectiveness at all concentrations (2.5%, 5%, and 10%), with no effect on Vickers microhardness. The 10% group had higher roughness than the other groups.

Comparison of shear bond strength of light cure mineral trioxide aggregate and light cure calcium hydroxide with nanofilled composite: A stereomicroscopic and scanning electron microscope analysis.

The quest for ideal pulp capping materials has given rise to the development of newer materials such as light cure mineral trioxide aggregate (MTA). The bond strength of the pulp capping materials with overlying restoration is one among the several factors that are critical for the success of vital pulp therapy. Hence, we conducted this study to evaluate and compare the shear bond strength (SBS) of light cure MTA and light cure calcium hydroxide with nanofilled composite. Thirty acrylic blocks each with a central hole were prepared to uniform dimensions and randomly distributed into two equal groups. In Group I, light cure MTA, and in Group II, light cure calcium hydroxide was used as pulp capping materials. After the application of adhesive system, nanofilled composites were applied onto the pulp capping material using a cylindrical plastic matrix. The SBS was tested on a universal testing machine (Instrom 3366, UK) at a crosshead speed of 0.5 mm/min. The samples were examined under stereomicroscope and scanning electron microscope to analyze different modes of failure. The results were statistically analyzed using independent sample t-test. Light cure MTA attained the mean SBS of 6.54 MPa and light cure calcium hydroxide attained the mean SBS of 6.56 MPa. There was no significant difference statistically in SBS of both the materials (P < 0.05). The modes of failure were predominantly mixed failure followed by cohesive failure within the restorative material in both Group I and II. The results of the study suggest that the SBS of light cure MTA and light cure calcium hydroxide is comparable. The modes of failure analyzed in both light cure MTA and light cure calcium hydroxide are not significantly different statistically. Hence, both materials can be successfully used as pulp capping material with nanofilled composite.

Experimental Studies on PV Module Cooling With Radiation Source PCM Matrix

Rise in PV module temperature (TPV) majorly drops the electrical output of the PV system. This research presents a novel cylindrical tube PCM matrix that is not in physical contact with the PV module back surface unlike the existing PCM based PV module cooling techniques. This contactless PCM matrix prevents the PV module from thermal and physical stress, also it blocks thermal energy re-conduction from PCM to PV module. While stored thermal energy from PCM retransferred to the PV module during off-sunshine hours and also when the PCM turns to liquid TPV starts to rise abruptly, this contactless PCM matrix minimizes these issues as PCM matrix receives thermal energy by the mode of radiation and convection; Besides, PCM matrix surface area is not enclosed with the PV module back surface area that reduces the thermal stress and re-conduction. Developed PCM matrix is integrated beneath the PV module at particular distances of 6 mm, 9 mm and 12 mm to optimize the spacing between PV module and PCM matrix. It is found that 6 mm spacing PCM matrix reduced the TPV maximum of 2.5°C compared to 9 mm and 12 mm spacing. This TPV reduction enhanced the PV module electrical output by 0.2 % than PV without PCM and it is observed that 6 mm is an optimal spacing for the radiation source PCM matrix.

Underwater Cylindrical Acoustic Array Structure Design Scheme

In this paper, the mathematical model of cylindrical array is analyzed. A cylindrical matrix structure scheme is designed for the complex environment of the ocean. The structure of the array is briefly introduced, and the situation of the array being affected by current and tow is carried out. The calculations show that the cylindrical array can resist the horizontal current impact and maintain its stability. In extreme cases, it needs more than 50t to lift the matrix or displace the array. The double cylindrical array arrangement can be used. Automatic tracking and monitoring of underwater moving targets is achieved within 300.

Nature—Inspired Flow Patterns for Active Magnetic Regenerators Assessed Using a 1D AMR Model

A novel flow structure of a solid active magnetic regenerator is proposed in this paper. The numerical performances of two nature-inspired flow geometries, based on double corrugated tubes with an elliptical cross-section, are compared to the performance of conventional flow structures for Active Magnetic Regeneration (AMR) applications, namely, packed spheres and a cylindrical micro-channel matrix. The numerical performance of all the geometries is analysed in terms of cooling power and coefficient of performance. Regenerators with various porosities and two different hydraulic diameters of the flow channels are evaluated varying utilisation at fixed temperature spans between the hot and cold reservoirs. The selection of the regenerator geometry is based on two actual AMR machines. The numerical results demonstrate that a suitably optimized AMR geometry with a double corrugated flow pattern provides the same or higher efficiency at higher porosity compared to conventional AMR flow geometries. These findings suggest that the magnetocaloric material used to construct AMR beds can be exploited more efficiently and at a lower investment cost of an AMR device when suitable double corrugated flow pattern is used.

Theoretical study of diffusional release of a dispersed solute from cylindrical polymeric matrix: A novel configuration for providing zero-order release profile

• A novel design for polymeric matrixes , containing dispersed solute, has been suggested for providing zero-order release. • Mathematical modeling and simulation have been carried out to evaluate the performance of the suggested system. • The effect of coating degradation rate on the release profile has been assessed through the mathematical simulation. • The effect of solute loading level on the release profile has been assessed through the mathematical simulation. • The suggested system is able to eliminate burst release at initial time and provide approximate zero-order behavior. In the context of controlled release drug delivery approaches, the systems providing zero-order release kinetics have special advantages. Through employing these systems, drug concentration could be maintained within the therapeutic window over release time; thus maximum effectiveness alongside minimized side effects of the drug are achieved. However, obtaining zero-order drug release is extremely challenging. One of the main obstacles is the fact that implemented devices should be designed to overcome the decreasing mass transfer driving force, especially, in polymeric systems in which diffusion mechanism is dominant. In this study, we developed a new configuration of a polymeric matrix containing dispersed solute which provides sustained zero-order release. A combination of two innovative approaches including separating baffles and a two-layer coating was proposed to be incorporated into the conventional cylindrical polymeric matrix to induce zero-order release behavior. Then, an approximate mathematical model was developed to investigate the performance of the system under different conditions. The simulated results showed the potential of proposed configuration to be used as a carrier for sustained zero-order release.

Defining parameters for control of extruding wire by friction process

Friction stir extrusion is an innovative direct-recycling technology for metal machining chips. During the process a specifically designed rotating tool is plunged into a cylindrical matrix containing the scraps to be recycled. The stirring action of the tool prompts solid bonding related phenomena allowing the back extrusion of a full dense rod. This process results to be particularly relevant because allows the reuse of the scrap without any previous treatment. Experiments have been carried out in order to investigate the influence of the process parameters on the extrudes quality and a numerical model has been developed in order to simulate the evolution of the material flow.

Theoretical research on kinematic and constructive parameters of roller presses for sweet sorghum

The overall objective of the project is to develop an eco-innovative system for pressing sweet sorghum by the generalised object method specific to the technical creation applied in this field. (Vitalie Belouasov). The representative technical solutions of the companies recognised in this field are known and it is necessary to use a creativity method to analyze the existing solutions, to assess technical and economic characteristics by methods specific to value analysis but also to find new constructive variants and choose the optimal variant that will then be developed by the design-research activity for the realisation of the technical documentation for the execution of an industrial prototype. The generalized object of the technical creation is in the form of a cylindrical morphological matrix, each sector representing a solution (sector represented by a triple assembly BiCjDk, the total number of solutions being: N=i·j·k solutions, some of which are known, others unknown. The incompatible ones must be eliminated, while the others must be analyzed, as they can lead to particularly efficient constructions after their complete solving.

The comparative evaluation of shear bond strength of a bioactive material to different universal bonding agents - An in vitro study.

Background:An ideal dental repair material should possess certain important properties such as adequate adhesive ability, insolubility, dimensional stability, biocompatibility, and bioactivity. Newer materials claiming better performance are continuously being introduced in the market to optimize the care of dental patients.Aim:The aim of this study was to evaluate the shear bond strength of three different universal adhesives to OrthoMTA.Materials and Methods:Sixty-four specimens of OrthoMTA measuring 4 mm internal diameter and 2 mm height were prepared and divided into two main groups. After 12 min, 32 samples were randomly selected and divided into four subgroups of eight samples each. Subgroup-I: Single Bond Universal, Subgroup-II: Prime-and-Bond NT, Subgroup-III: Palfique Universal bond, Subgroup-IV: Control. After the application of adhesives, the composite resin was applied using a cylindrical plastic matrix of 2 mm internal diameter and 2 mm height over OrthoMTA. This procedure was repeated 24 h after mixing an additional 32 samples, respectively. Shear bond strengths were measured using Universal testing machine and fractured specimen were examined under stereomicroscope. Data were statistically analyzed using a two-way ANOVA test and Tukey's multiple post hoc test.Results:Statistical analysis revealed that subgroup-III exhibited higher bond strength at both 12 min and 24 h time intervals. It was also observed that most of the failures occurred cohesively within OrthoMTA.Conclusion:Shear bond strength was higher at 24 h than compared to 12 min. Subgroup-III exhibited higher bond strength than other subgroups.

Modeling and Fabrication of a Multi-Axial Piezoelectric Energy Harvester Based on a Metamaterial-Inspired Structure

Due to the limited availability and high depletion rates of nonrenewable energy sources as well as environmental concerns, the scientific community is urged to explore and harness alternative, clean energy sources. In this paper, a novel piezoelectric energy harvester based on a metamaterial structure is proposed, which is capable of scavenging energy from low-frequency, multi-axial ambient vibrations. The proposed energy harvester is based on a mass-in-mass phononic crystal structure and is comprised of a spherical heavy core resonator and piezoelectric wafers, encapsulated in a cylindrical rubber matrix, and encased in a rigid cubic frame. The proposed cell behaves effectively such as a negative mass in the vicinity of its resonance frequencies and entraps the vibration energy as dynamic strain. The captured kinetic energy is then transformed to electric potential using three lead–zentrale–Teichmann wafers, optimally embedded in the cell’s soft constituent. In this paper, the proposed energy harvester cell is analytically modeled, numerically simulated via COMSOL Multiphysics software, and experimentally validated using a variety of uni- and multi-axial vibration excitations.

Fabrication of a thick three-dimensional scaffold with an open cellular-like structure using airbrushing and thermal cross-linking of molded short nanofibers

Nanoscale fibers mimicking the extracellular matrix of natural tissue can be produced by conventional electrospinning, but this approach results in two-dimensional thin dense fibrous mats which can hinder effective cell infiltration. The aim of the present study was to design a thick, three-dimensional (3D) cylindrical scaffold with an open pore structure assembled from short polycaprolactone (PCL) fibers using a facile airbrushing approach. In addition, magnesium particles were incorporated into the PCL solution to both enhance the mechanical properties of the scaffold and stimulate cellular activity following cell seeding. Separated short composite airbrushed fibers were assembled into a 3D cylindrical structure by cold-press molding and thermal cross-linking. The microstructure, chemical composition, porosity and thermal properties were subsequently investigated, along with changes in mechanical performance following immersion in PBS for 60 d. The results showed that the assembled 3D fibrous 10 mm thick cylindrical matrix had an interconnected fibrous network structure with 31.5%–60% porosity. Encapsulation of the Mg particles into the 3D assembled fibrous scaffold enhanced the mechanical properties of the plain PCL scaffolds. The results also demonstrated controlled release of Mg ions into the PBS media for up to 60 d, as evaluated by changes in Mg ion concentration and pH of the media. In addition, the 3D fibrous assembled matrix was shown to support human osteoblast-like cell adhesion, proliferation and penetration. The results suggest that this novel fabrication method of biodegradable thick 3D scaffolds with an open pore structure is promising for the production of a new generation of 3D scaffolds for tissue regeneration applications.

3D Printed Rotating Acentric Binary-Disk Electrode.

Rotating ring-disk electrode (RRDE) is a generator-collector electrochemical system widely used as an electroanalytical and kinetic device. However, RRDEs are costly and difficult to fabricate, particularly when the electrode material is fragile, small, and scarce. Taking advantage of readily available 3D printing technology an alternative generator-collector system was developed: rotating acentric binary-disk electrode (RABDE). RABDE consists of two close acentric disk electrodes arranged in a cylindrical matrix so that the line connecting their centers is perpendicular to radius of the device passing through the center of generator electrode. In contrast to RRDE that is based on radial flow velocity for mass transfer between the generator and the collector, RABDE mostly takes advantage of the larger tangential flow velocity. RABDE thus exhibits higher current densities than RRDE for a same rotation rate and evidences much better electroanalytical performances. These increased performances were tested and quantified using typical analytes: potassium ferricyanide system, copper ion system, and oxygen reduction reaction in alkaline solution.

Recycling Chips of Stainless Steel by High Energy Ball Milling

Stainless steel components produced by powder metallurgy constitute an important and growing segment of the industry. The high energy ball milling process can be an alternative for the recycling of the stainless steel chips. A major advantage of stainless steel is its ability to be recyclable. The reuse of recyclable materials has as main objectives to minimize the environmental impacts and to rationalize the use of the energy chains. This work aims at the production of stainless steel, starting from machining chips pure, and with the addition of vanadium carbides by high energy planetary milling with ball to powder weight ratio 20:1, and mill speed of 350 rpm milled in argon atmosphere for 50h. The compaction of stainless steel samples with vanadium carbide was made in a cylindrical matrix at a pressure of 700 Mpa. The sintering process was performed in a vacuum atmosphere furnace at a temperature of 1200 ° C for 1h. Through the milling process with the addition of carbide it was possible to produce stainless steel powder with a mean particle size of 49 μm. By X-ray diffraction was observed the appearance of the ferritic, austenitic phase and the martensitic phase induced by deformation phase that remained even after the sintering. The density of the sintered material is around 77% of the melt, and the obtained porosity was low.

Polymer Brushes: Efficient Synthesis and Applications.

Polymer brushes are special macromolecular structures with polymer chains densely tethered to another polymer chain (one-dimensional, 1D) or the surface of a planar (two-dimensional, 2D), spherical or cylindrical (three-dimensional, 3D) solid via a stable covalent or noncovalent bond linkage. In comparison with the corresponding linear counterpart with similar molecular composition, one-dimension polymer brushes have some fascinating properties including wormlike conformation, compact molecular dimension, and notable chain end effects due to their compact and confined densely grafted structure. The introduction of polymer chains onto the surface of planar and spherical or cylindrical matrix will not only significantly change the surface-related properties of the matrix but also endows the obtained hybrid polymer brushes with new functionalities. Thus, polymer brushes are of great interest in the fields of polymer and material science due to their broad applications, such as catalysis, nanolithography, biomineralization, drug delivery, medical diagnosis, optoelectronics, and so on. Although a variety of 1D, 2D, and 3D polymer brushes have been prepared with the advent of living/controlled polymerization, the development of more efficient and facile synthetic protocols that permit access to polymer brushes with precisely controlled composition, structure, and functionality still represents a key contemporary challenge. In this Account, we summarize our recent efforts on the development of efficient methods to prepare 1D, 2D, and 3D polymer brushes and exploration of their potential applications in drug delivery, antifouling coating, catalysis, and lithium-ion batteries and also highlight related achievements by other groups. First, we briefly introduce the precedent examples of efficient synthesis of polymer brushes with different structures and functionalities by the combination of monomer design with living/controlled polymerization. Given the excellent tolerance and use of the same catalytic system without any mutual interference of ATRP and Cu-catalyzed alkyne-azide cyclization (CuAAC) click reaction, a versatile and efficient platform for precise synthesis of complex asymmetric (Janus-type) 1D polymer brushes was developed on the basis of the "trifunctional monomer" strategy without polymeric functionality transformation. Subsequently, a noncovalent strategy based on crystallization-driven self assembly to prepare well-defined polymer brushes with precise control over their composition and dimensions is described. Notably, the crystallization-driven self assembly can be treated as a living/controlled polymerization of "polymeric monomer" with a special building segment for crystallization, which allows for preparing linear polymer brushes with length as high as tens of micrometers. Moreover, the properties and related applications of polymer brushes as interesting building blocks for constructing hierarchical nanostructures, efficient drug deliver carriers, antifouling films, and lithium-ion batteries are addressed by some typical examples. These advancements in this field will provide a new avenue for obtaining fascinating polymer-brush-based functional materials.

A cylindrical assembly model and dynamics of the Ebola virus VP40 structural matrix

The Ebola filovirus causes severe hemorrhagic fever with a high fatality rate in humans. The primary structural matrix protein VP40 displays transformer-protein characteristics and exists in different conformational and oligomeric states. VP40 plays crucial roles in viral assembly and budding at the plasma membrane of the infected cells and is capable of forming virus-like particles without the need for other Ebola proteins. However, no experimental three-dimensional structure for any filovirus VP40 cylindrical assembly matrix is currently available. Here, we use a protein-protein docking approach to develop cylindrical assembly models for an Ebola virion and also for a smaller structural matrix that does not contain genetic material. These models match well with the 2D averages of cryo-electron tomograms of the authentic virion. We also used all-atom molecular dynamics simulations to investigate the stability and dynamics of the cylindrical models and the interactions between the side-by-side hexamers to determine the amino acid residues that are especially important for stabilizing the hexamers in the cylindrical ring configuration matrix assembly. Our models provide helpful information to better understand the assembly processes of filoviruses and such structural studies may also lead to the design and development of antiviral drugs.