Basic Material Properties Research Articles

Prosthodontic Rehabilitation of a Patient Suffering from Ectodermal Dysplasia – A Case Report

Ectodermal dysplasia is a rare congenital disease that affects several ectodermal structures. Children with ectodermal dysplasia may have various manifestation of the disease that differ in severity and may involve teeth, skin, hair, nails, sweat glands and sebaceous glands. A 16 years Old girl reported in the department of Prosthodontics and crown bridge,with chief complain of of inability to masticate and her unesthetic appearance. She desired replacement of her missing teeth. Family history revealed similar findings in her 18-year old brother. Clinical findings and family history suggested a diagnosis of hypohydrotic ectodermal dysplasia. The present clinical report demonstrated that maxillary flexible RPDs associated with direct composite restorations, Zirconia crowns and mandibular complete denture with CEKA supported Stud attachment are a reversible, relatively inexpensive method of treatment for ectodermal dysplasia patients especially during their growth years. The esthetic, light weight, and good retentive and fracture properties of the flexible denture base materials make a good alternative to the conventional and cast partial dentures.

Comparative Evaluation of Flexural and Impact Strength of Denture Base Acrylic Resin using Different Processing Methods - An in-vitro Study

Background: One of the chief limitations of Polymethylmethacrylate denture base material is its inadequate mechanical property. Different processing methods of Polymethylmethacrylate have varying influences on the mechanical properties of denture base material. Aim: The aim of our in-vitro study was to comparatively evaluate the flexural and impact strength values between CAD-CAM, Compression-molded and Injection- molded Polymethylmethacrylate specimens. Materials and methods: A total of 66 acrylic rectangular specimens of ISO Standardization (64 x10 x3.3mm) were fabricated. This study was conducted between three groups: Group I (n=22)-CAD-CAM Milled specimens (Ruthinium, India), Group II (n=22)- Compression-molded specimens (Dental Products of India, Chennai), Group III (n=22)- Injection-molded specimens (SR- Ivocap High Impact, Ivoclar Vivadent). Flexural strength was evaluated using four-point bend test and Impact strength by IZOD Impact tester. Kruskal Wallis unpaired test was used to compare the mean values between groups and Mann Whitney U test was used to carry out pair wise comparison. Results: Flexural strength of CAD-CAM samples were found to be statistically highest followed by injection molded specimens. Conversely, Impact strength of injection- molded specimens were highest followed by CAD-CAM specimens. Flexural as well as impact strength values were found to be least among compression-molded specimens. Conclusion: CAD-CAM specimens exhibited higher flexural strength whereas Injection-molded specimens had the highest impact strength.

Impact of Fines on Various Base Material Properties

The performance of the unbound aggregate base is affected by moisture content and fines (materials finer than No. 200 sieve) content. Proper moisture content and the proper amount of fines in a base material contribute to long-lasting pavements. This study evaluated an unbound aggregate base under different moisture contents and fines contents. The evaluation included the measurements of the electrical and electromagnetic properties with moisture content and fines content. The dielectric constants were measured with a percometer, and the resistivity values were measured using a Wenner probe. These measurements were correlated with the moisture content for all fines contents used in the study. Strength and modulus tests were also performed on the specimens using the unconfined compressive strength (UCS) tests and a lightweight deflectometer (LWD). The variations in these parameters with moisture content are also presented here for all fines content. A normalization scheme was used to allow for the data to be compiled and analyzed more easily. The dielectric constant increased as moisture was added with some dispersion, but no clear trend was seen among different fines contents. The resistivity decreased consistently as the moisture content increased. The peak UCS normally occurred at moisture contents of about 1% dry of optimum moisture content (OMC); specimens prepared with 1% less than optimum had higher UCS. LWD modulus tended to peak when prepared drier than OMC. The optimum strength and modulus were obtained with 5% and 10% fines contents for the unbound granular base used.

Flow field disturbance due to point viscosity variations in a heterogeneous fluid

A fluid can be heterogeneous in either its density or viscosity - its two basic material properties. In this Letter, we ask how an ambient flow field is disturbed due to a point viscosity variation in the fluid. If we are able to answer this question, we can create an arbitrary spatial distribution of viscosity discretely by placing viscosity sources and sinks of appropriate strength, allowing us to model complex fluids. As an example, we show how the hydrodynamics of a rigid particle is altered due to the presence of point viscosity variations.

Enhancement of PMMA base Denture Material: A Review

As we know Teeth problems can be prominent as age increases also due to accident teeth breaks. Physical appearance can be greatly affected by teeth. So we need to test material which has better or similar properties to the natural teeth before restoring teeth with suitable material. Therefore, it is important to study the physical and mechanical properties of denture base material. Denture base material properties can be improved by adding various monomers and cross linking agent. Focus is on the increase of impact strength other mechanical properties of denture material. Different additives being used should be compatible with MMA (Methyl methacrylate) and polymerize to PMMA (Poly methyl methacrylate). Heat cure and variation in chemical composition can affect the mechanical properties. This paper presents the review of the work that has been done to improve the properties of denture base material and the problems being faced during the fabrication. The gap in the literatures available has been also discussed.

A comparative evaluation of effect of denture cleansers on color stability, surface roughness and hardness of polyamide denture base material.

Different denture cleansers have an effect on color and different surface properties of polyamide denture base material. Thus, selecting a denture cleanser solution for polyamide denture base materials should be based on the properties of the denture cleanser itself. The present in vitro study is aimed to evaluate and compare the effect of different denture base cleansers on color, surface roughness and hardness of polyamide denture base material. Thirty specimens of commercially available polyamide denture base material were fabricated and divided into three groups of 10 each. Specimens from each group were immersed in different denture cleansers (sodium perborate, thyme oil and ozonated water) for 10 mins per day for 180 days. Initial and final color, surface roughness and surface hardness of each specimen were measured and the difference was calculated. Data was tabulated and subjected to statistical analysis using One way ANOVA for pair wise comparison. Polyamide denture base resin exhibited some degree of change in color, surface roughness, and surface hardness in all denture cleansers but was not statistically significant. The choice of denture cleanser for different denture base resins should be based on the chemistry of resin and the cleanser, denture cleanser concentration and duration of immersion.

Multiwavelength tissue-mimicking phantoms with tunable vessel pulsation

For the development and routine characterization of optical devices used in medicine, tissue-equivalent phantoms mimicking a broad spectrum of human skin properties are indispensable. Our work aims to develop a tissue-equivalent phantom suitable for photoplethysmography applications. The phantom includes the optical and mechanical properties of the three uppermost human skin layers (dermis, epidermis, and hypodermis, each containing different types of blood vessels) plus the ability to mimic pulsation. While the mechanical properties of the polydimethylsiloxane base material are adjusted by different mixing ratios of a base and curing agent, the optical properties are tuned by adding titanium dioxide particles, India ink, and synthetic melanin in different concentrations. The layered structure of the phantom is realized using a doctor blade technique, and blood vessels are fabricated using molding wires of different diameters. The tissue-mimicking phantom is then integrated into an artificial circulatory system employing piezo-actuated double diaphragm pumps for testing. The optical and mechanical properties of human skin were successfully replicated. The diameter of the artificial blood vessels is linearly dependent on pump actuation, and the time-dependent expansion profile of real pulse forms were mimicked. A tissue equivalent phantom suitable for the ex-vivo testing of opto-medical devices was demonstrated.

Characteristic of particles created by preparatory operationsof the particleboard production process

Characteristic of particles created by preparatory operations of the particleboard production process.The production of wood-based panels, taking into account material innovations, involves the need to adjust the operation of technological devices to the properties of basic and auxiliary materials. In this study, it was decided to check the particle sizes after sorting raw materials representing 3 groups: forest biomass – pine branches, agricultural biomass - oilseed plant straw, and post-production material. Fractions were taken from the 2.00 mm mesh sieve of a sorter for the core layer of the particleboard and the fractional composition was determined by sieve analysis. The average linear particle dimensions and bulk density of each lignocellulosic raw material were also determined. Due to the varying proportions, it is necessary to adapt the parameters of the technological operations to the specifics of the raw material being processed or to introduce guidelines for the selection of particle sizes guided by their actual average size. Studies have shown differences between the individual materials. This is particularly important, as proper preparation of the raw material translates into the quality of the boards produced from them and the efficiency of the entire process.

Physico-Mechanical Properties of a Newly Developed Base Material Containing Mineral Trioxide Aggregate

The aim of this study was to evaluate the physico-mechanical properties of a new cavity base material containing mineral trioxide aggregate, LA-T1, prototyped by Neo Dental Chemical Products for indirect restoration. Three base materials, LA-T1, Cavios (CAV, Neo Dental Chemical Products), and Bulk Base Hard (BBH, Sun Medical), were examined. The depth of cure, microshear bond strength with a resin-based luting cement, and the compressive strength of these materials were investigated. The depth of cure of LA-T1 was similar to that of CAV, while the depth of cure of BBH was above the measurement limit. The distance from the base material to the light source, 0 mm and 4 mm, did not significantly affect the depth of cure of all materials. The microshear bond strength of LA-T1 bonded to a resin-based luting cement was slightly higher than that of CAV and similar to that of BBH, both of which were bonded to the same luting cement under the same conditions. The compressive strength of LA-T1 was similar to that of CAV but less than that of BBH. The results of this study indicate that LA-T1 has properties that are similar to those of CAV and thus can be clinically applied.

Improved Fatigue Performance and Cost-Effectiveness of Natural Rubber Latex–Modified Cement-Stabilized Pavement Base at Raised Temperatures

The increased temperature at the early state of curing affects the fatigue properties of pavement base materials. The fatigue properties of stabilized pavement bases and subbases govern the performance and service life of pavement structures. This research study utilized natural rubber latex (NRL) to enhance the tensile fatigue properties of cement-stabilized base materials at various temperatures. The effects of influence factors such as cement content (3%, 5%, and 7%), NRL replacement ratio (0%, 10%, 15%, 20%, 25%, and 30%), and temperature (25°C, 40°C, and 60°C) on indirect tensile strength (ITS), indirect tensile resilient modulus (IT Mr), and indirect tensile fatigue life (ITFL) were studied in this research. NRL replacement was found to improve the UCS, ITS, IT Mr, and ITFL of cement (C)-stabilized soil up to the highest values at the optimum NRL replacement ratios, which were 20%, 15%, and 10% for cement contents of 3%, 5%, and 7%, respectively. The cement-NRL (C-NRL)-stabilized samples were found to have superior ITS, IT Mr, and ITFL values compared with C-stabilized samples for the same cement content but had the same rate of reduction in ITS due to the raised temperature. For the NRL replacement ratio on the dry side of optimum, the C-NRL-stabilized samples had lower rate of IT Mr reduction than the C-stabilized samples, although they had the same ITS due to the higher toughness. Therefore, the rate of ITFL reduction of C-NRL-stabilized samples was lower than that of the C-stabilized samples. It was proven in this research that the NRL replacement could reduce the thickness (superior IT Mr) of a cement-NRL-stabilized base course for a given traffic volume and service life, and therefore the construction (material and operation) cost by 17.26% benchmarked to a C-stabilized base course. Finally, the cost-effective design method for C-NRL-stabilized bases course was proposed, which will promote the use of NRL as an alternative green additive instead of synthetic polymer.

Performance-Based Characterization and Quantification of Uncertainty in Damage Plasticity Model for Seismic Fragility Assessment of Concrete Structures

Seismic probabilistic risk assessment requires explicit consideration and quantification of all sources of uncertainty. Although uncertainties in earthquakes and basic material properties, such as nominal concrete compressive strength, strain at maximum stress, and modulus of elasticity of concrete, have been considered in some studies, uncertainties in parameters used to model the nonlinear behavior of concrete are often not considered. Recent recommendations in design standards have incorporated performance-based limit states in the design and risk assessment of nuclear power plants. These recommendations have implicitly mandated that the uncertainty in the nonlinear behavior of concrete needs to be characterized and quantified in accordance with different performance limit states. This study focused on nonlinear model parameters in the concrete damage plasticity model (CDPM) and their characterization in terms of material strength parameters. Furthermore, a performance-based characterization and quantification of uncertainties in nonlinear model parameters was also conducted. Data from existing experimental studies were used to study the uncertainties in CDPM and were used as a basis for the proposed quantification.

Modeling and characterizing the dynamic response of Octet-Truss lattice structures using elastic parameters determined from Resonant Ultrasound Spectroscopy

Modeling and characterization of additively manufactured materials and structures is a critical stage in the design process. This presentation will present an approach using Resonant Ultrasound Spectroscopy to determine the elastic tensor of an additively manufactured Octet Truss lattice structure. The lattice structures are fabricated from an alloy of Titanium using a laser powder bed fusion process. Material characterization begins by applying resonance techniques on simple regular parallelepiped shapes. Solid and lattice samples are measured to obtain estimates for the elastic properties of the bulk material and the effective elastic properties of the lattice structure. The measured elastic properties are then incorporated into structural models representing continuum approximations of several test parts. Comparisons between the continuum models and the experimental measurements indicate agreement over a wide frequency range within a long wavelength approximation defined for the lattice. The measurements also suggest that there is additional physics and geometrical effects accounted for in the RUS continuum approximations of the lattice that are not completely captured by the full finite model utilizing only base material properties.

Study of Inductive Reactance of a Micro Strip Line Structure with The Spacing Between Two Metal Strip

The Present Paper aims at the study of inductive property developed due to propagation of electromagnetic waves through the structure and its dependence on the spacing between two metal strip and other factors. Due to interaction of electron beam with electromagnetic waves, kinetic energy of electron is increased. Microwaves have become very powerful experimental tools for study of some of the basic properties of materials. There are different structures for the propagation of electromagnetic powers in different modes. The Microwave Integrated circuits (MIC’S) have changed the systems in the present days by replacing large scale waveguides and co-axial component arrays to small light weight assemblies. These introduced microwave striplines, microslotlines, coplanar strip lines and coplanar waveguide etc.

Specific application method for determining the strength and fracture toughness of metal materials

The elastic–plastic fracture of metal components with cracks is an interesting structural behavior because of the sizable crack-tip plastic zone and its strong interactions with the structural boundaries and load conditions. These complex interactions lead to constant elastic–plastic fracture phenomenon that does not exist normally. Currently, there are several restrictions, such as specific height, thickness, initial crack length, loading fixture, and loading method, on the test specimens to determine the fracture toughness of metal materials. Considering the plastic zone at the crack tip, it is proposed that the elastic–plastic fracture phenomenon of metals can be predicted entirely by two basic material properties, tensile yield strength and fracture toughness. A 40 mm wide plate is used to test ordinary carbon steel Q235B, low alloy carbon steel Q345B and aluminum alloy 6061 under tension. The initial cracks introduced through wire-cutting were 4, 8, 12, 16, 20, 24, and 28 mm in dimensions with the initial notch length to the width ratios of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7. Based on the elastic–plastic fracture model, the specific application method for determining the strength and fracture toughness of metal materials was realized, and the complete failure curves of three metal materials were determined.A cruciallinkbetween the structural behavior and material parameters of metal materials was established, which can predict the yield load of actual large-scale metal structures based on the elastic–plastic fracture model.

Experimental research on standardized bamboo culm components for developing prefabricated bamboo building

Bamboo culm structures are useful for areas with limited access to structural wood, especially for remote bamboo forest areas. This study focuses on developing standardized bamboo culm components for the prefabricated bamboo building, which is potential to replace timber components made of dimension lumber used in modern timber buildings. The basic material properties of Moso bamboo and bamboo culm elements were investigated. Test results show that the main mechanical properties of bamboo culm are comparable to some coniferous wood, such as TC-13A grade (in Chinese standard). Several types of simple and reliable connectors were designed for connecting bamboo culms, attempting to provide standardized bamboo culm elements. The prefabricated shear wall elements were designed with bamboo culms as studs and glubam lumber as perimeter frame for regulate the dimension. Three shear wall models were tested under monotonic and cyclic lateral loading. It was found that the lateral resistance capacity of bamboo culm shear wall is about 64% of that of the similar lightweight wood frame shear walls. Three specimens of bamboo culm trusses were also tested to obtain the design capacity of the roof system. Based on the experimental test results, a prototype single-story building was designed and constructed to assess the feasibility of the constructional details. Carbon dioxide emission analysis revealed the environmentally friendly advantages of this type of bamboo building.

ANALYSIS OF OIL ABSORPTION AND FRICTION COEFFICIENT OF BAMBOO POWDER, COCONUT POWDER, GLASS POWDER, AND COPPER POWDER COMPOSITES FOR CLUTCH PADS

This study aims to determine the characteristics of the absorption test with SAE 10W-30 and the friction coefficient test with the ASTM D 3702-94 test standard on composite clutch pads made from bamboo powder, coconut powder, glass powder, and copper powder. It is based on the considerations that there are abundance of natural resources of bamboo and coconut with that is still not optimally utilized as well as the discovery of several hazardous clutch lining (asbestos) basic material properties. In each test, each composition variation was tested 3 times and from the data, the average value of the composition variation was taken. Based on this research, the specimen with the highest oil absorption value is specimen combination 3 (BB20KL20CU0KC20) with an absorption value of 17.98% and the specimen with the lowest absorption value is specimen combination 2 (BB20KL20CU5KC15) with an absorption value of 4.88%, and the specimen with the highest percentage change in volume is specimen combination 1 (BB20KL20CU10KC10) with a percentage of 3.30%, and the specimen with the lowest percentage change in volume is specimen combination 2 (BB20KL20CU5KC15) with a percentage of 1.01%. From the results of the combined friction coefficient test, specimen 3 (BB20KL20CU0KC20) has the highest friction coefficient value of 0.54526 and specimen 2 (BB20KL20CU5KC15) has the lowest friction coefficient value of 0.16923.

Modeling and characterizing the elastodynamic response of octet-truss lattice structures using resonance techniques

Characterization of additively manufactured materials and structures is an ongoing effort for the advanced manufacturing community. This article will investigate an approach using resonant spectral ultrasound (RUS) to measure the effective elastic constants of an Octet Truss lattice and apply the results to continuum bases models representing the lattice regions in different structures. The study is focused on simple lattices structures fabricated from Ti5553 using a laser powder bed fusion process (LBPF). Solid and lattice samples are measured to determine RUS estimates for the elastic properties of the bulk material and the effective elastic properties of the lattice structure. The estimated elastic properties are then incorporated into 3d finite element models using a continuum approximation of the physical AM parts. Comparisons show good agreement between the experimentally measured eigen frequencies of the Ti5553 LBPF parts and the eigen frequencies calculated using the continuum approximations based on the effective RUS elastic properties. The current results suggest there is additional physics and geometrical effects that are accounted for in the RUS continuum approximation of the lattice that are not captured in the full 3d finite element model of the parts utilizing only the base material properties.

Degradation of limestone calcined clay cement (LC3) mortars under sulfate attack

Limestone Calcined Clay Cement (LC3 is a newly proposed low-carbon cement, which can effectively reduce energy consumption and carbon emissions of the traditional cement industry without changing the basic mechanical properties of cement-based materials. In this study, the degradation process of mortar samples of limestone and calcined clay cementitious material under sulfate attack is studied by both macroscopic and microscopic analysis. The results show that compared with pure Portland cement, the addition of calcined clay and limestone can significantly reduce the expansion rate, loss of dynamic modulus and mass loss of mortar specimens under sulfate attack. The addition of calcined clay and limestone will refine the pore size distribution of mortar specimens, then inhibiting the diffusion of sulfate and formation of corrosive products, therefore leading to a significant improvement of the sulfate resistance.

Towards Highly Efficient Nitrogen Dioxide Gas Sensors in Humid and Wet Environments Using Triggerable-Polymer Metasurfaces.

We report simulations on a highly-sensitive class of metasurface-based nitrogen dioxide (NO2) gas sensors, operating in the telecom C band around the 1550 nm line and exhibiting strong variations in terms of the reflection coefficient after assimilation of NO2 molecules. The unit architecture employs a polymer-based (polyvinylidene fluoride-PVDF or polyimide-PI) motif of either half-rings, rods, or disks having selected sizes and orientations, deposited on a gold substrate. On top of this, we add a layer of hydrophyllic polymer (POEGMA) functionalized with a NO2-responsive monomer (PAPUEMA), which is able to adsorb water molecules only in the presence of NO2 molecules. In this process, the POEGMA raises its hidrophyllicity, while not triggering a phase change in the bulk material, which, in turn, modifies its electrical properties. Contrary to absorption-based gas detection and electrical signal-based sensors, which experience considerable limitations in humid or wet environments, our method stands out by simple exploitation of the basic material properties of the functionalized polymer. The results show that NO2-triggered water molecule adsorption from humid and wet environments can be used in conjunction with our metasurface architecture in order to provide a highly-sensitive response in the desired spectral window. Additionally, instead of measuring the absorption spectrum of the NO2 gas, in which humidity counts as a parasitic effect due to spectral overlap, this method allows tuning to a desired wavelength at which the water molecules are transparent, by scaling the geometry and thicknesses of the layers to respond to a desired wavelength. All these advantages make our proposed sensor architecture an extremely-viable candidate for both biological and atmospheric NO2 gas-sensing applications.

Behaviour and material properties of versaloc semi-interlocking mortarless masonry

Masonry construction is popular around the world, but the use of mortared masonry presents numerous challenges. In recent decades, masonry construction systems incorporating interlocking masonry units have been proposed to eliminate mortar. The interlocking between masonry units can be achieved using specially shaped units. This paper presents a comprehensive experimental study to determine the behaviour as well as basic material properties of one such semi-interlocking mortarless masonry. The experiments included testings of ungrouted masonry units, prisms, and wallets. In addition, masonry prisms and wallets with grouted cores were also investigated to study the effect of grouting. A detailed description of the construction procedure is explained. The failure mechanisms, maximum strengths, force–displacement relationships, and modulus of elasticity of the samples are obtained and contrasted with the relevant results from the literature. Finally, recommendations are made that may assist material model development required for micro- and macro-modelling of mortarless masonry. The new information generated in this research will enable better understanding of the behaviour and properties of semi-interlocking mortarless masonry and will be useful for validating numerical models in future research.