Intrinsic Material Characteristics Research Articles

Evaluation of pavement response and performance under different scales of APT facilities

This paper focuses on comparative evaluation of pavement responses and performance under accelerated loading facility (ALF), Model Mobile Load Simulator 3(MMLS 3) and Asphalt Pavement Analyzer (APA) tests, in terms of rut depth, strain response, seismic stiffness and contact stress. Test slabs extracted from the ALF test lanes were trafficked with the MMLS3 under comparable environmental conditions at a laboratory in Virginia Tech. Some small specimens were cut from the slab for APA tests at VTRC. It is found that the monitored parameters yielded by the MMLS 3 test were comparable to the related full-scale ALF test results in terms of intrinsic material characteristics and pavement performance. It is concluded that MMLS 3 is an effective, economic and reliable trafficking tool to characterise rutting and fatigue performance of pavement materials with due regard to the relative structures. The APA test is not suitable to assess the fatigue resistance of pavement material, but is an efficient and effective method to rank rutting resistance of asphalt mixtures. The MMLS 3 test can be employed as the screen testing for establishing full-scale testing protocols as desired or required, which will significantly enhance economics of APT testing.

Fabrication of micro and sub-micrometer wrinkled hydrogel surfaces through thermal and photocrosslinking processes

Abstract Micro-morphology control of films is fundamental to adapt a particular material for their final application. The strategy depicted in this study permits the spontaneous formation of corrugated patterns using a two-step procedure involving an initial thermal pre-polymerization followed by UV exposure. Two deposition methods, electrospray and spin coating were explored; interestingly, spin coating forms homogeneous topography that cover large areas of the substrate, permitting an ease control of the micro-structure. Equally, the wrinkle pattern was modulated through the variation of intrinsic material characteristics, in particular molecular weight of the crosslinking agent. The results obtained indicate that their increase produces the same effect in wrinkle amplitude and wavelength, and therefore, in their roughness. This behavior can be explained by the stiffness decrease according to the PEGDA molecular weight increase. As a result, an increase of available surface from ∼14% up to ∼29% was observed. Consequently, this versatile approach allows to modulate the surface pattern according to the application needed just by finely tuning the hydrogel composition.

Osteolytic and mixed cancer metastasis modulates collagen and mineral parameters within rat vertebral bone matrix.

Metastatic involvement in vertebral bone diminishes the mechanical integrity of the spine; however minimal data exist on the potential impact of metastases on the intrinsic material characteristics of the bone matrix. Thirty-four (34) female athymic rats were inoculated with HeLa (N = 17) or Ace-1 (N = 17) cancer cells lines producing osteolytic or mixed (osteolytic and osteoblastic) metastases, respectively. A maximum of 21 days was allowed between inoculation and rat sacrifice for vertebrae extraction. High performance liquid chromatography (HPLC) was utilized to determine modifications in collagen-I parameters such as proline hydroxylation and the formation of specific enzymatic and non-enzymatic (pentosidine) cross-links. Raman spectroscopy was used to determine relative changes in mineral crystallinity, mineral carbonation, mineral/collagen matrix ratio, collagen quality ratio, and proline hydroxylation. HPLC results showed significant increase in the formation of pentosidine and decrease in the formation of the enzymatic cross-link deoxy-pryridinoline within osteolytic bone compared to mixed bone. Raman results showed decreased crystallinity, increased carbonation, and collagen quality (aka 1660/1690 sub-band) ratio with osteolytic bone compared to mixed bone and healthy controls along with an observed increase in proline hydroxylation with metastatic involvement. The mineral/matrix ratio decreased in both osteolytic and mixed bone compared to healthy controls. Quantifying modifications within the intrinsic characteristics of bone tissue will provide a foundation to assess the impact of current therapies on the material behavior of bone tissue in the metastatic spine and highlight targets for the development of new therapeutics and approaches for treatment. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2126-2136, 2016.

Effects of deer age on the physicochemical properties of deproteinized antler cancellous bone: an approach to optimize osteoconductivity of bone graft

Inorganic bone xenograft materials have recently found extensive surgical application in the clinic. Previously we have demonstrated that calcinated antler cancellous bone (CACB) has great potential for bone defect repair, due to the similar structure and composition compared with human bone. However, the effect of intrinsic material characteristics, particularly deer age, on the physicochemical and biological properties of CACB scaffolds has not been clarified. The aim of this study is to investigate the structure, composition and in vitro solubility of CACB scaffolds derived from deer of varying ages, including young (CACB-Y), middle-aged (CACB-M), and old (CACB-O) deer, and to determine subsequent biological performance. Microstructural analyses showed looser crystal arrangement and lower porosity in CACB-M compared to CACB-Y and CACB-O. Phase-structure analysis showed that CACB-M had the largest crystal size. Component characterization results showed that CACB-M had the most carbonated substitute and the highest content of trace elements (Na, Fe). The in vitro solubility test showed that CACB-M had the fastest dissolution and apatite deposition rates with new crystalline phases. In addition, CACB-M could be conducive for attachment, proliferation and osteogenic differentiation of rat bone marrow mesenchymal stem cells in vitro, as well as conducive for bone regeneration in vivo. These findings indicate that animal age should be seriously considered as a key parameter in optimizing the physicochemical and biological properties of deproteinized antler cancellous bone substitutes for bone regeneration applications.

A computational model for the sound absorption coefficients of multi-layer non-wovens

Using the theory of Zwikker and Kosten for sound propagation through a porous flexible media and the sound propagation boundary conditions at adjacent interfaces, a general computational model for the sound absorption coefficients of multi-layer non-wovens, αn, is presented in this paper. The iterative algorithm for calculating αn is given using the back-stepping method. In order to yield the highest sound absorption coefficients in the audible frequency range the model has been used for numerical calculation of the intrinsic characteristics of non-woven materials. The simulation demonstrates that the multi-layer structure of non-wovens can have good sound absorption over a prescribed frequency range by choosing the appropriate parameters for each layer. This model can also be used to calculate the absorption coefficients of a multi-layer non-woven comprising different non-woven components, and this can then provide a theoretical support for product design.

Microstructural Characterization of Granular Cast Iron for Permeable Reactive Barriers

AbstractAlthough intensive research on Fe(0) permeable reactive barriers (PRB) for in situ groundwater remediation has been conducted and multiple applications have been installed in the past two decades, some properties of reactive materials in use have not been fully considered and discussed yet. In the present investigation, a typical granular cast iron has been characterized with different techniques. The grain size distribution not only has an influence on the resulting pore geometry and the surface area but material properties significantly differ between fine and coarse grains. Metallographic analyses revealed large differences in both graphite inclusions and microstructures that likely influence the reactivity. Both graphite and cementite proved to be more resistant toward acidic dissolution compared to Fe0. The intrinsic material characteristics described here have not been covered in the existing PRB literature.

Threshold behavior of phase transition characteristics in germanium telluride glasses doped with Ag

In this article, the overall phase transition behavior of a Ge–Te–Ag system prepared by co-sputtering Ag and pure GeTe was investigated over a wide Ag composition (0–39.3 mol%). Crystallization temperature was determined through an electrical resistance analysis. The crystalline phase was analyzed with X-ray diffraction measurement, selected area electron diffraction patterns, and high resolution transmission electron microscopy to study the effects of Ag incorporation into GeTe. Optical static tests were conducted to measure the energy of crystallization, and a crystallization kinetics study was also performed using the Johnson–Mehl–Avrami model. Optical band gap was also measured using a UV–Vis–NIR spectrophotometer. We found that the system displayed a compositional threshold behavior, wherein crystallization temperature first decreased with increasing Ag content and then increased with further increases in Ag content. Crystallization kinetics and crystallinity also showed the compositional threshold behaviors at the critical Ag composition. From understanding of the origin of these results, we expect this research to provide a means of manipulating intrinsic characteristics of phase change materials to achieve targeted performance.

Modified Cyclic Shear Test for Evaluating Disturbance Function and Numerical Formulation of Geosynthetic–Soil Interface Considering Chemical Effect

Abstract Geosynthetics have been broadly used in waste landfill sites for filtration, drainage, and separation. Geosynthetics contact soil directly, creating a geosynthetic–soil interface corresponding to the external forces and conditions. The differences in the intrinsic material characteristics at the interface induce complicated stress–strain behaviors and strain-softening processes. Recent studies have presented the behaviors of geosynthetic–soil systems as depending on the interface shear strength degradation, which is affected by ambient factors such as the water content, chemical condition, etc. In this study, the disturbed state concept (DSC) and a disturbance function are introduced to explain the cyclic shear stress behavior of the interface. The degree of interface damage can be expressed by the disturbance function, and the shape of the disturbance function curve represents the intrinsic characteristics of the material. Massive sets of cyclic shear tests have been performed to investigate the effects of the pH values of leachates on the shear behavior of the geosynthetic–soil interface. Both geosynthetics and Jumunjin sand have been submerged in acid, neutral, and basic solutions for 200 days. A multi-purpose interface apparatus that can simulate the cyclic shear conditions of a geosynthetic–soil interface has been newly manufactured and modified for better performance. Test results display remarkable distinction in chemical degradation trends according to the pH values. New disturbance function parameters that determine the characteristics of the shear strength of the interface were estimated according to the chemical conditions as well. Furthermore, it was discovered via focused ion beam electronic microscopy that the different patterns of damage on the surface of soil particles with different pH values induce variation in the disturbance phase at the geosynthetic–soil interface. For the numerical formulation of the disturbance function, the constitutive equations of the DSC were modified using the Mohr–Coulomb model. Based on the modified DSC equations, verification and numerical implementation shall be performed for further study.

Progress in Research on Manganese Dioxide Electrode Materials for Electrochemical Capacitors

Besides presenting the intrinsic characteristics of manganese dioxide electrode materials, the worldwide research progress in their preparation and application for electrochemical capacitor are introduced in this article. Moreover, the future development trend and prospects are discussed.

Research Progress on Manganese Dioxide Electrode Materials for Electrochemical Capacitors

Based on presenting the intrinsic characteristics of manganese dioxide electrode materials,the research progress of preparation and its application for electrochemical capacitor were introduced in this article.Moreover,the future development trend is prospected.

Effect of wall friction on variation of formwork pressure over time in self-consolidating concrete

In order to accurately predict the varying of formwork pressure over time, it is necessary to consider various factors influencing the development of formwork pressure. A prediction model has been previously proposed, but that model has some limitations in that only intrinsic material characteristics are taken into account. Extrinsic effects such as wall friction, formwork flexibility, and external temperature are excluded in the model. This study focuses on the wall friction effect as one of the extrinsic factors. First, by incorporating the intrinsic model and friction stress acting on the interface, a method of calculating formwork pressure considering the wall friction effect is suggested. To find out how much friction stress is acting on the interface and how it varies over time, formwork pressure tests were performed with circular column formworks having three different diameters. In these columns, the vertical pressure at the bottom and the lateral pressures were measured. To calibrate parameters of the intrinsic model for the same material as that used in the formwork pressure tests, additional tests were conducted with a specially designed apparatus that can exclude effects of extrinsic factors. From tests and analysis results, it was found that wall friction greatly affects the variation of formwork pressure over time. The newly suggested calculation method can give a good prediction of real formwork pressure.

Intrinsic Model to Predict Formwork Pressure

Formwork pressure depends on many factors. Some are related to the intrinsic characteristics of concrete while others are extrinsic factors related to the external environment and formwork conditions. In this study, a model is proposed to simulate the change of formwork pressure over time due solely to the effect of the intrinsic material characteristics. In addition, a new apparatus was devised to measure the formwork pressure in isolation from the extrinsic factors. Tests were performed using three mixtures: cement paste (CP), ordinary concrete (OC), and self-consolidating concrete (SCC). The formwork pressures predicted and measured in the experiment are compared considering discrete and continuous casting situations. From the comparison, it is verified that the proposed model can predict the response of the lateral pressure with respect to a time-varying vertical pressure.

On-line Measurement Studies on Orientation Development and Characteristic Short-Period Diameter Fluctuation in High Speed In-line Drawing of Poly(ethylene terephthalate) Fiber

Abstract To investigate the orientation development behavior in high-speed in-line drawing process of poly(ethylene terephthalate) filament, simultaneous on-line measurements of diameter and optical retardation were conducted under various spinning and drawing conditions. In the measurement of optical retardation, the order of interference could be determined successfully from the successive assembly of phase shift versus filament diameter correlations collected at different measuring positions along the spinning and drawing lines. Analyzed birefringence increased steeply in the vicinity of neck-like deformation in the high-speed spinning line or in the vicinity of necking deformations in the in-line drawing line. It was verified that the thinning in the in-line drawing line is more effective for the development of molecular orientation in comparison with that in the high speed spinning line. Analysis on the time-course variations of diameter and birefringence in the vicinity of neck-like deformation caused by the fluctuation of its position along the spinning line was conducted to obtain detailed orientation development behavior. This analysis confirmed that the local birefringence is governed solely by the local diameter (or velocity) in the high-speed spinning line. On the other hand, it was relatively difficult to analyze the time-course variation of birefringence near the necking deformation in the in-line drawing line because of an overlapping of unique short-period diameter fluctuation of around 125 Hz, which corresponds to several tens of centimeters along the filament, occurring during the necking deformation. Such diameter fluctuation moves toward downstream at the speed of running filament, and therefore was speculated to be originated from the intrinsic characteristics of fiber materials.

“Bottleneck Effect” in Two-Dimensional Microfluidics

An anomalously long transient is needed to achieve a steady pressurization of a fluid when forced to flow through micronarrowed channels under constant mechanical driving. This phenomenon, known as the "bottleneck effect" is here revisited from a different perspective, by using confined displacements of interfacial fluids. Compared to standard microfluidics, such effect admits in this case a neat quantitative characterization, which reveals intrinsic material characteristics of flowing monolayers and permits to envisage strategies for their controlled micromanipulation.

Intrinsic characteristics of cathode and anode materials for lithium-ion batteries

Fundamental aspects of solving the problem of how the working capacity of lithium-ion batteries in prolonged cycling can be raised and the basic tendencies in the relationship between the intrinsic parameters of active materials of various brands and the electrochemical behavior of anodes and cathodes fabricated from these materials are considered.

Combined approach of NMR and chemometrics for screening peptones used in the cell culture medium for the production of a recombinant therapeutic protein

Soy peptones or soy hydrolysates are widely used as key medium additives in serum-free cell culture processes for industrial production of therapeutic recombinant proteins. The heterogeneous nature of these vegetable-derived materials can lead to substantial lot- to-lot variability in cell culture processes. In this study, we demonstrated the feasibility of nuclear magnetic resonance (NMR) spectroscopy in combination with chemometrics in rapid screening peptone lots in order to optimize efficiency and consistency of large-scale protein production. This report is the first that shows a correlation between the intrinsic NMR spectral characteristics of complex heterogeneous materials and product titer using chemometrics.

Generational, skeletal and substitutional diversities in generation one poly(amidoamine) dendrimers

Structural deviations of ethylenediamine core polyamidoamine (PAMAM) dendrimers and derivatives can be defined as skeletal and/or substitutional diversities. Detailed analysis of dendrimer starting materials and derivatives is necessary to understand the intrinsic characteristics of commercial dendrimer materials and their variations related to subsequent surface modifications. In this paper, structural deviations of ethylenediamine core generation 1 PAMAM dendrimers (PAMAM_E1 or E1) are studied and determined in a frame of a systematic investigation using combined characterization techniques. A primary amine-terminated PAMAM dendrimer of generation 1 (E1.NH 2) was used as a starting material to synthesize glycidol (E1.N(Gly)OH) and acetamide-terminated (E1.NHAc) dendrimers. The purity and homogeneity of these dendrimers were extensively characterized by polyacrylamide gel electrophoresis (PAGE), capillary electrophoresis (CE), gel permeation chromatography (GPC), acid–base titration, nuclear magnetic resonance (NMR), matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) and electrospray ionization (ESI) mass spectrometry. PAGE and CE studies showed that electrophoretic mobilities at pH 2.5 are in the order of E1.NH 2>E1.N(Gly)OH>E1.NHAc. Mass spectrometry and NMR investigations ( 1H, 13C DEPT-135, and 13C NMR, COSY, HETCOR, NOESY) suggested that (a) the studied E1 dendrimers were generationally pure, (b) E1.NHAc and E1.N(Gly)OH dendrimers, and essentially had the same defects and skeletal diversity as E1.NH 2 did. The broad distribution of the main peak in the CE electropherogram of E1.N(Gly)OH revealed the incomplete hydroxylation of E1.NH 2 resulting in additional substitutional diversity between the dendrimer molecules. Potentiometric titration studies proved that overall numbers of terminal and tertiary amine groups also deviated from the theoretical values. NMR spectroscopy was applied for both qualitative and quantitative analysis of the structural defects of dendrimers and derivatives. E1.NH 2 and E1.NHAc exhibited only minor deviations from ideal structures and, respectively, displayed a narrow distribution; while E1.N(Gly)OH had a much broader distribution centered around 14±3 glycidol substituents. The study of structural variations in generation 1 PAMAMs provides new insights for the characterization of higher generation PAMAM dendrimers and derivatives both in terms of the skeletal deviations as well as other resulting diversities related to dendrimer surface functionalization.

Plane strain crack problems for elastic materials with variable properties

Distributions of stress, strain and displacement occurring at the tip of a crack in a material with properties dependent on the type of loading are investigated for the conditions of plane strain in both far-field tensile and shear loads. The causes of the dependence of material properties on the type of external forces are the various inhomogeneities such as microcracks, pores, inclusions or reinforcing components in a material. The behaviour of these inhomogeneities depends substantially on the conditions of loading or deformation. Hence, the deformation properties of a material are not fixed intrinsic material characteristics that are invariant to the loading conditions, but rather the macroproperties of such materials are stress-state-dependent ones, and this effect becomes more noticeable as the volume content of the inhomogeneities increases. The asymptotic solutions of crack problems are obtained on the basis of proposed stress-strain relations describing not only the stress-state dependence of material properties, but the interrelation between the characteristics of volume and shear deformation as well. In a non-uniform stress state the primary macrohomogeneous material becomes an heterogeneous one. The use of the stress function is not effective for the solution of plane strain crack problems for the materials under consideration. Therefore, an approach based on the corresponding representation for the strains is used. It is shown that the commonly used suppositions of the symmetry or anti-symmetry in the stress distribution relative to the crack plane can not be accepted, since they do not allow all the boundary conditions to be satisfied. The opening of the crack surfaces in the case of far shear field is observed. The influence of stress-state sensitivity of material properties on the values of the stress intensity factor is more significant for tensile crack than for the crack in far shear field.

Skin ageing: changes of physical properties of human skin in vivo

We have investigated in vivo the change with age of various parameters that describe the physical properties of skin. The parameters were derived from pressure/displacement curves obtained by applying reduced pressure to a small area of skin and measuring the resulting displacement by 20 MHz scan echography. By fitting the pressure/displacement curves to a theoretical model, the following skin parameters were obtained: E, Young's modulus or stiffness (in Pascals); sigma(0), the initial stress (in Pascals); and the unrestored energy ratio (UER), an index related to cutaneous non-elasticity. These parameters, which are used in mechanics to define the intrinsic physical characteristics of materials, were measured for the first time on volar forearm skin of 206 male and female subjects, aged between 6 months and 90 years. The results showed that skin thickness increases until maturity and decreases for women over 50-60 years old, Young's modulus E increases linearly with age, and ageing is divided into two phases for natural stress, sigma(0) and the non-elasticity index UER. Natural stress sigma(0) increases until maturity and then rapidly decreases. The non-elasticity index decreases until puberty and steadily increases after puberty. This new procedure provides a simple quantitative assessment of the physical properties of the skin, revealing that the skin becomes thinner, stiffer, less tense and elastic with ageing.

Hot-compaction behaviour of char/ binder-coal systems

Hot-compaction behaviour of semi-anthracite coal char, sub-bituminous coal char and coke fines with a moderately caking hvAb binder coal has been studied in the temperature range at which binder coal softened. The binder-coal softening temperature was observed to be significantly lower in the compaction equipment than in the Ruhr dilatometer. Isothermal compaction curves can be fitted to an equation of the form ϵ = ΔL L 0 = K(1 − Ae −αt − Be −βt − Ce −γt) , from which a viscoelastic model consisting of a series coupling of three Kelvin elements has been developed. Of these six mechanical components four (two viscous and two elastic components) are found to be temperature-sensitive. These temperature-sensitive elements are assigned to 1. (1) the softening of the binder phase (one viscous and one elastic component decrease rapidly to minimum), and 2. (2) interparticle flow (one viscous and one elastic component go through a maximum before being reduced to near zero). The temperature-insensitive components are assigned to the overall press set-up and intrinsic material characteristics. While some of the physical properties such as packing density and particlesize distribution are similar in these char systems, large differences in their viscous and elastic coefficients have been observed. This is probably caused by the wetting behaviour of the binder and some inherent physical properties of the chars.