Measurements Of Dimensional Changes Research Articles

Radiation-induced alteration of sandstone concrete aggregate

This study investigates the alteration of felsic sandstone-type rock, which is used as a coarse aggregate in concrete, subject to the effects of gamma-ray and neutron irradiation. The effects of three gamma-ray doses (27, 55, and 108 MGy) and four neutron fluence levels (1.22, 2.19, 6.99, and 14.30 × 1019 n/cm2, E ≥ 0.01 MeV) were investigated. Quartz and albite were found to be the major rock-forming minerals, with microcline intermediates, chlorite, and muscovite as the minors. Gamma rays caused no significant changes to the physical properties of the sandstone aggregates, even at high doses (108 MGy). In contrast, neutron irradiation caused alterations that became more pronounced at higher neutron fluences. The solid was confirmed to expand through metamictization of the rock-forming minerals. Quartz and muscovite were the most affected phases, whereas albite and microcline intermediates were only slightly affected, and chlorite was almost unaffected. The decrease in density was measured by He and water pycnometry, and this value was almost reproduced by calculations using the rock-forming mineral composition of the pristine sample measured using X-ray powder diffraction/Rietveld analysis and the cell volume change of the major forming minerals. In addition, light optical microscopy and scanning electron microscopy images confirmed the presence of intergranular and intragranular cracks. Intergranular cracks appeared to have initiated from the quartz grains, which expanded significantly. The intragranular cracks were frequently observed in the albite and microcline intermediates. These cracks can be described as radial cracks starting from the expanding quartz, caused by enforced displacement for deformation consistency with quartz expansion. The crack area ratio quantified by SEM image analysis corresponds to the discrepancy of the volume expansion difference calculated by He or water pycnometry and dimensional change measurements. An evaluation of solid expansion and crack openings in aggregates is important to estimate concrete degradation.

Cold reaction sintering for preparation of ultra-dense geopolymer products

Geopolymers are attractive materials that contribute to carbon neutrality because they can significantly reduce CO2 emissions compared to traditional Portland-based cement manufacturing. Geopolymers generally take several days to weeks to cure and have low mechanical properties. This paper proposes a new hardening method using a warm press, called “cold reaction sintering“, in order to obtain a hardened body with high strength in a shorter time than conventional geopolymers. In general, to harden geopolymers use an alkaline solution such as NaOH. In this study, sodium metasilicate hydrate (Na2SiO3·nH2O) was used instead of the alkaline solution. As a result of examining the composition, temperature and holding time, the maximum compressive strength value of 425 MPa was obtained when hardened at uniaxial pressure 100 MPa, 130° C for only 10 min with fly ash: Na2SiO3: Na2SiO3·9H2O (68: 16: 16 wt%, respectively). In addition, dimensional change measurements during hardening, FTIR and NMR analysis were preformed to investigate and discuss the mechanism of geopolymer hardening.

Spatio-temporal monitoring of humidity induced 3D displacements and strains in mounted and unmounted parchments

The high hygroscopicity and heterogeneity of parchment make it particularly sensitive to changes in environmental conditions. The proper housing of a historical parchment, including mounting should mitigate the impact of the changes on the object. However, finding an appropriate mounting method requires detailed knowledge of the mechanical response of a parchment on the combined influence from environmental changes and forces introduced by the mounting. In this paper we present the capabilities of 3D digital image correlation (3D DIC) method implemented for full-field, spatio-temporal monitoring of displacements and strains in parchment exposed to environmental changes. We combine the measurement concept with the particular, critical task of evaluating the effectiveness of stabilising a single sheet of parchment mounted using elastic polyester strips. 3D DIC is implemented to record in non-invasive and non-contact way the full-field response of parchment mock-ups to fluctuations of the relative humidity (RH) without interfering with the climatic chamber processes. We measure and compare the impact of fluctuating RH on unmounted and mounted parchment samples, through the full-field 3D measurements of dimensional changes at selected humidity levels, and through the local and global analysis of the samples’ response (displacement/strains) in time. We had proven in quantitative and detailed way that the applied mount fully fulfils its task, namely reduce significantly the out-of-plane displacements and strains occurring in the parchment during RH changes in the range from 39 to 80%. Our study also demonstrates the possibilities of using 3D DIC for the efficient support of conservation scientists in the development of storage, mounting, and treatment protocols for historical parchment.

Alterações dimensionais em pastas de óxido de zinco/eugenol: um novo método para sua mensuração

After an extensive review of the literature, regarding zinc.oxide/eugenol impression pastes, we selected 20 of the most representatives as our references. Trough personal information of several of the investigators it was discovered that dimensional changes of theese materials is one of the most difficult properties to be measured. A new method was developed to measure dimensional changes ot 4 (four) of the most widely used zinc.oxide/eugenol impression materials in Brazil. The results, presented through several graphs and tables showed that dimensional changes varied from 0,003%, values which may probably be considered negligible from a clinical point of view. We noticed, however, high values for standard deviation and variance which indicate the high variability within the experiments. Those values were not found when we used the same method with mercaptan and silicone impression materials, in which the measurement of dimensional changes was highly reproducible. One hypothesis (which we intend to investigate in a later research) is that, during storage, a sedimentation could occur, of the components of greater density! Consequently ther might result a change in composition, independent of the method used to establishe the proportion of the two pastes, be it by wheight or measurement of lenght, which could be the cause of variability of the composition of each mixture!

Extended-pour and conventional alginates: effect of storage time on dimensional accuracy and maintenance of details.

ABSTRACTObjective: This study aimed to evaluate the dimensional stability and maintenance of details of conventional and high stability alginates up to 5-day storage. Methods: Two types of alginates were selected (n=10) for this study, conventional (Hydrogum) and high stability alginates (Hydrogum 5), which were produced with the aid of a cylindrical metal block and a ring-shaped metal mold (Specifications 18, 19, and 25, ANSI/ADA). Ten images were obtained from the molds for the dimensional stability test, which were taken immediately after their production and at each different storage periods (15 min, 24 h, 48 h, 72 h, 96 h, and 120 h) by a digital camera. The specimens were kept hermetically sealed in plastic bags (23°C) and then used to obtain 140 (n=70) dental stone models, used in the detail reproduction test, in which the angular accuracy of three grooves (20 µm, 50 µm, and 75 µm) was observed at each period. The details reproduction accuracy was classified using a predetermined score classification. Measurements of dimensional changes were made in the Corel DRAW X6 program. The data were submitted to the Student’s t-test (α?#8197;= 0.05). Results: A statistically significant difference concerning the size of the matrix was observed after 24h for both alginates, and a statistically significant negative linear dimensional change (contraction) was verified after 24 h of storage (1.52% for the high stability alginate, and 1.32% for the conventional alginate). The high stability alginate kept the full details for 72 hours, while the conventional alginate, for 24 h. Both alginates reproduced the 75 µm groove at all storage periods. Conclusion: Impressions made with both alginates presented satisfactory clinical results when the alginates were immediately poured.

UV-C Irradiation-induced Crosslinking of PVP on PES/CO Knitted Fabric: Textile Properties and Surface Evaluation

Knitted fabrics are widely used in the textile and garment industry. However, dimensional change (DC) and pilling can occur during production and also after use. To reduce these undesirable effects, a polymeric coating with poly(N-vinyl-2-pyrrolidone) (PVP) and crosslinking via UV-C irradiation was performed on a 50:50 % polyester/cotton (PES/CO) knitted fabric. The influence of the crosslinking process was evaluated through DC measurements (in the direction of the courses and wales), determination of the degree of pilling, water repellency and bursting strength. Infrared Fourier transform spectroscopy and scanning electron microscopy were used to evaluate the surface of the fabric. The results indicate that the PVP crosslinked with UV-C irradiation on the PES/CO surface decreased the degree of pilling (grade 4 for the coated knitted fabric compared with grade 1 for the uncoated knitted fabric) and the DC, without influencing the hydrophilicity and bursting strength.

Dimensional Changes of Nb3Sn Rutherford Cables During Heat Treatment

In high field magnet applications, Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn coils undergo a heat treatment step after winding. During this stage, coils radially expand and longitudinally contract due to the Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn phase change. In order to prevent residual strain from altering superconducting performances, the tooling must provide the adequate space for these dimensional changes. The aim of this paper is to understand the behavior of cable dimensions during heat treatment and to provide estimates of the space to be accommodated in the tooling for coil expansion and contraction. This paper summarizes measurements of dimensional changes on strands, single Rutherford cables, cable stacks, and coils performed between 2013 and 2015. These samples and coils have been performed within a collaboration between CERN and the U.S. LHC Accelerator Research Program to develop Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn quadrupole magnets for the HiLumi LHC. The results are also compared with other high field magnet projects.

Electrospun Bipolar Membranes for Portable Fuel Cells

Shifting to high pH fuel cell operating environments could potentially lower the overall fuel cell costs by reducing or replacing noble metals with other electrocatalytically-active non-noble metal materials. Anion-exchange membranes (AEMs) with mobile OH- ions are one way to shift to higher pH environments, and have received attention for use in alkaline fuel cells.[1] Most AEMs studied to-date are organic and exhibit low chemical stabilities and low ionic conductivities (i.e. mobile transport ions are OH-, CO3 2- or mixed ion form) after prolonged exposure to high pH media and temperatures greater than 60°C.[2] A number of advancements have been made for increasing the ion-exchange group stability for reasonable ion-conductivities by using phenyl guanidinium-[3], imidazolium-[4] and other metal-cation exchange groups[5]. Park et al. recently demonstrated a novel approach for creating AEM membranes by electrospinning.[6] The electrospinning approach allows for short- and long-range fabrication, which is useful for proton- and/or hydroxide-transport membranes. In addition to the electrocatalyst and membrane materials concerns, fuel cells commonly employee auxiliary components to assist in balancing the water production and consumption at the anode and cathode compartments.[7] The auxiliary components cause the total fuel cell device (i.e. composed of stack and other components) to increase in size and weight. One way to reduce the logistics burden and overall balance of plant (BOP) is to design bipolar membranes that are comprised of an acid membrane component spatially separated from an alkaline membrane component. The bipolar membrane concept was recently demonstrated by Unlu et al.[8] The reduction in the BOP would therefore reduce the overall cost and size of the fuel cell device. In this study, we synthesize AEM and PEM precursors and subsequently co-electrospin these precursors into a bipolar membrane. The bipolar membrane produced may be potentially used for portable hybrid acid-alkaline fuel cells. The electrospun PEM component is primarily made of Nafion embedded in an inert matrix layer. The electrospun AEM component is comprised of a synthesized and subsequently modified polysulfone derivative embedded in an inert matrix layer. We provide physical characterizations such as TEM, SEM, BET, swelling and dimensional change measurements to understand each electrospun component at the PEM and AEM compartments. Moreover, we perform ex-situ ion-transport measurements for bulk conductivities of the isolated and combined components. Figure 1 shows a schematic of the electrospinning process whereby a rotating roll configuration with multiple high voltage power supplies is utilized for fabricating a co-electrospun bipolar membrane. An SEM image is shown for the AEM fiber mat component, which is typically placed at the cathode compartment. Acknowledgements We gratefully acknowledge the fuel cell team at the U.S. Army Research Laboratory. We acknowledge the U.S. Department of the Army and Army Materiel Command for funding and support.

Alterations of mouse lung tissue dimensions during processing for morphometry: A comparison of methods

Preservation of original tissue dimensions is an essential prerequisite for morphometric studies. Shrinkage occurring during tissue processing for histology may severely influence the appearance of structures seen under the microscope and stereological calculations. Therefore, shrinkage has to be avoided so that estimates obtained by application of unbiased stereology are indeed unbiased. The present study investigates the alterations of tissue dimensions of mouse lung samples during processing for histology. Different fixatives as well as embedding protocols are considered. Mouse lungs were fixed by instillation of either 4% formalin or a mixture of 1.5% glutaraldehyde/1.5% formaldehyde. Tissue blocks were sampled according to principles of stereology for embedding in paraffin, glycol methacrylate without treatment with osmium tetroxide and uranyl acetate, and glycol methacrylate including treatment with osmium tetroxide and uranyl acetate before dehydration. Shrinkage was investigated by stereological measurements of dimensional changes of tissue cut faces. Results show a shrinkage of the cut face areas of roughly 40% per lung during paraffin embedding, 30% during "simple" glycol methacrylate embedding, and <3% during osmium tetroxide/uranyl acetate/glycol methacrylate embedding. Furthermore, the superiority of the glutaraldehyde-containing fixative regarding shrinkage is demonstrated. In conclusion, the use of a glutaraldehyde-containing fixative and embedding in glycol methacrylate with previous treatment of the samples with osmium tetroxide and uranyl acetate before dehydration is recommended for stereological studies of the mouse lung.

Densification and thermal gradient evolution of alumina during microwave sintering at 2.45 GHz

This paper presents research on the densification and thermal gradient evolution of pure and magnesia-doped alumina during microwave sintering in a multimode cavity. Dimensional changes of pellets are registered by a contactless dilatometer that is part of a specifically prepared experimental system. Measurements of dimensional changes are compared to results obtained during sintering in the conventional dilatometer and show a palpable effect of microwaves when alumina is doped by magnesia. This system also allows monitoring of temperature distribution on the surface sample from temperatures of about 700°C. Analysis of thermal evolution shows gradient inversion for both examined powders.

In situ proton irradiation-induced creep at very high temperature

This objective of this work was to develop an experimental facility that can perform in situ high temperature proton irradiation-induced creep experiments on a range of materials. This was achieved by designing an irradiation chamber and stage that allows for load application and removal, provides a method for controlling and monitoring temperature and proton flux, and a means to make in situ measurement of dimensional change of the samples during the experiment. Initial experiments on POCO Graphite Inc. ZXF-5Q grade ultra-fine grain samples irradiated at 1000°C at a damage rate of 1.15×10−6dpa/s exhibited a linear dependence of measured creep rate on applied stress over a range of stresses from 10MPa to 40MPa.

Method to Estimate Thermal Shrinkage Behavior of Glasses

We present a method to estimate the effect of heat treatment on the shrinkage behavior of glasses. As a pre‐requisite, sensitivity of the glass density as a function of glass fictive temperature is measured using the sink–float method and the slope of the relationship is used to determine the linear thermal strain proportionality factor. Evolution of the fictive temperature for different temperature–time history is measured using the infrared spectroscopy method and the results are used to estimate the structural relaxation parameters in the temperature range of interest. The overall shrinkage behavior is predicted using the linear thermal strain factor and estimated change in fictive temperature due to the thermal treatment. The predicted shrinkage behavior is observed to be in good agreement with the independent dimensional change measurements performed on large glass sheets that have undergone similar thermal treatments.

FE analysis of the sensitivity of friction calibration curves to dimensional changes in a ring compression test

This paper is concerned with an analysis of the sensitivity of friction calibration curves to the frictional shear factor in a ring compression test. The main objective of this study is to examine the sensitivity of the FEA calibration curves of a ring compression test to the frictional shear factor. Different calibration curves were investigated by measuring dimensional changes at different positions of a ring specimen, including changes in the internal diameter at the middle and top section of the specimen, the outer diameter at the middle and top section, and the degree of surface expansion at the top surface. The initial ring geometries employed in the analysis maintain a fixed ratio of 6:3:2, i.e., the outer diameter: inner diameter: thickness ratio of the ring specimen, which is generally known as a ‘standard’ specimen, in order only to determine the sensitivity of the calibration curves for the measurement of dimensional changes at different positions to the frictional shear factor. A perfectly plastic material was modeled for the simulations using rigid-plastic finite element code. Analyses were performed within a definite range of friction as well as over the entire range of friction to uncover the different sensitivities of calibration curves to interfacial friction given different ranges of friction. The results of this investigation are summarized in terms of a dimensionless gradient. It was determined from the results that the friction calibration curves according to measurements of the dimensional changes at different positions of a ring specimen show different degrees of linearity and sensitivity to the frictional condition on the contact surface. Among these differences, the friction calibration curve upon changes in the degree of surface expansion at the contact boundary was found to be relatively linear and sensitive to the frictional condition over the entire range of friction.

Dimensional change measurements of conventional and flowable composite resins using a laser displacement sensor

The polymerization shrinkage values of commercial flowable and conventional composites were measured with a newly developed laser displacement sensor. Compressive strength and filler content were also measured. Compared to conventional composites, the flowable composites required a longer time - not exceeding 4 minutes - to reach a constant polymerization shrinkage rate. In terms of shrinkage ratio, it was less than 1.5% for conventional composites at 90 minutes, which was lower than that of flowable composites, i.e. more than 2.0%. The compressive strength of conventional composites was higher than that of flowable composites. A highly significant correlation between filler content and polymerization shrinkage at 90 minutes was observed, and polymerization shrinkage tended to decrease as filler content increased. In light of the results obtained in this study, the newly developed displacement meter with a laser displacement sensor proved to be effective for in-depth investigation of the polymerization shrinkage of dental composites.

A double-pass interferometer for measurement of dimensional changes

A double-pass interferometer was developed for measuring dimensional changes of materials in a nanoscale absolute interferometric dilatometer. This interferometer realized the double-ended measurement of a sample using a single-detection double-pass interference system. The nearly balanced design, in which the measurement beam and the reference beam have equal optical path lengths except for the path difference caused by the sample itself, makes this interferometer have high stability, which is verified by the measurement of a quasi-zero-length sample. The preliminary experiments and uncertainty analysis show that this interferometer should be able to measure dimensional changes with characteristic uncertainty at the nanometer level.

Technique for the measurement of dimensional changes of natural microfibril materials under variable humidity environments

An algorithm was developed to analyze the dimensions of line scan data of step-shaped disconitunities acquired with an atomic force microscope. The effect of a number of AFM parameters on the quantitative imaging of step features was discussed. Quantitiative imaging using AFM was shown to be very reproducible as five successive scans of a standard step height grating produced less than 3% variation in measured parameters. A cellulose microfibril, called cellulose aggregate fibril (CAF), with dimensions of ∼50,000 nm × 2000 nm × 300 nm derived from papermaking fibers was scanned under cyclic relative humdity conditions with the relative humidity starting at 50% then raising to 80% followed by a decrease in the relative humidity to 28%. Changes in the width of the CAF were weakly correlated with changes in the relative humdity, while changes in the height and area of the CAF were positively correlated with the relative humdity. The length of the CAF was negatively correlated with the given relative humdity cycle. These findings have significant implications in paper dimensional stability and the engineering of cellulose micro and nano-fiber composites.

In situ measurement of dimensional changes and temperature fields during sintering with a novel thermooptical measuring device

With a novel thermooptical measuring device (TOM) dimensional changes are investigated during sintering of components and samples up to 50 mm in size. Sintering shrinkage is measured without contact using an optical method. This optical method additionally enables the monitoring of warpage, cracking and caking phenomena which often occur in developing new sintering processes. Creep, caused by uniaxial loading of the samples, can also be measured in the axial and transverse direction. Simultaneously, thermal diffusivity and heat transfer coefficients are measured by the laser-flash technique. Material properties are obtained by an inverse simulation of the temperature distribution in the sample.

Examination of the role of oxygen in the photografting of methacrylic acid on a polyethylene film with a mixed solvent consisting of water and organic solvents

AbstractThe photografting of methacrylic acid (MAA) on a linear low‐density polyethylene film (thickness = 30 μm) under air and nitrogen atmospheres was investigated at 60°C in mixed solvents consisting of water and an organic solvent, with xanthone as a photoinitiator. The organic solvents used were acetone, methanol, tetrahydrofuran, and dioxane. A maximum percentage of grafting occurred at a certain concentration of the organic solvent in the mixed solvent. This was observed for the systems under both air and nitrogen. The grafting reaction under air exhibited an induction period, but the rate of grafting after the period was greater than that under nitrogen. The formation of poly(ethylene peroxide)s by photoirradiation seemed to be a factor for the accelerated photografting under air. On the basis of attenuated total reflection infrared spectroscopy and scanning electron microscopy of the grafted film, the MAA‐grafted chains of the sample prepared under air tended to penetrate more deeply inside the film than those of the sample prepared under nitrogen. The resulting grafted films exhibited a pH‐responsive character: the grafted films shrank in an acidic medium but swelled in alkaline medium. This was evaluated from measurements of dimensional changes in the grafted films. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 992–998, 2003

Focus on Magnetics

Focus on Magnetics

A precise radiographic technique for the measurement of dimensional changes in heart valve biomaterials following fixation

Accurate tissue thickness measurements are difficult to acquire by present techniques. Error is introduced by tissue compression during measurements or by tissue processing prior to measurement. In the field of valve replacement, tissue dimensional changes from fixation prior to implantation may predispose implants to premature tissue failure and it becomes important to have an accurate method for comparing cusp dimensions pre- and post-fixation. A new approach is to use high-resolution digital radiography to make thickness maps of entire specimens. For 25 matched porcine aortic valve cusps, we have evaluated this technique's ability to measure and compare thickness, surface area and volume before and after 7 days of aldehyde fixation. Digital radiographs were acquired pre- and post-0.5% glutaraldehyde ( n=13) or 10% formaldehyde ( n=12) fixation. Mean thickness, surface area, volume and four measurements to evaluate shape differences with fixation were obtained and compared pre- and post-fixation using paired t tests. The results demonstrate that this X-ray imaging technique can provide dimensions of matched fresh and fixed specimens and is sensitive enough to show statistically significant changes due to fixation. These findings also illustrate that aldehyde fixation can cause tissue contraction resulting in a significant overall increase in tissue thickness and a decrease in surface area. This technique could be used to gain further insights into tissue anatomy and mechanics.