Measurement Of Volume Changes Research Articles

Simultaneous thermal and contraction / expansion curves analysis for solidification control of cast irons

The first part of the paper summarizes the performance of two mould devices, illustrating by representative shrinkage tendency results in ductile cast iron as affected by mould rigidity (green and furan resin sand moulds) and inoculant type (FeSi-based alloys). Less rigid green sand moulds encourage the formation of contraction defects, not only because of the high initial expansion values (εdi)max, but also because of the increased solidification undercooling. A high inoculation efficiency means not only lowering the carbides formation sensitivity and increasing the nodule count, but also a prolonged graphitization through to the end of the eutectic freezing, as observed by the high population of small late forming nodules, which leads to minimizing the tendency for shrinkage. The second part of the paper illustrates an application of this equipment to commercial foundry use. It conducts thermal analysis and volume change measurements in a single ceramic cup with cast iron quality as a variable. La-bearing FeSi inoculant appears to be more effective than RE (Rare Earth) -FeSi alloy in FeSiMgCa treated irons (no RE), in terms of reducing eutectic undercooling and (εdi)max, favourable for lower sensitivity to shrinkage formation. Experiments also compared solidification patterns for white [WI], grey [GI] and ductile [DI] irons, to correlate the most important events between the cooling curves and contraction curves, to evaluate the sensitivity to shrinkage formation. All of the irons have similar values for initial expansion up to the start of eutectic freezing, but, after that, the graphite formation promotes expansion (more than 5 times for nodular graphite), resulting in a difference in maximum expansion (2 times higher for DI). The graphitic expansion has two contrary effects. Increased graphitic expansion (force) leads to a higher shrinkage sensitivity during the first part of the eutectic reaction, but also to a decrease of shrinkage at the end of solidification, due to forcing the last liquid iron to occupy the previous formed cavities. Consequently, strong graphitization process promotion at the end of solidification favours the castings' soundness.

Experimental Measurement, Modeling and Calculation of Volume Changes of Cement Concrete

The paper describes experimental measurement of volume changes of cement concrete. Volume changes include swelling and shrinkage of cement concrete specimens measured by string strain gauges both internal and external. Parallel to this measurement, the volume changes will be measured by means of shrinkage drains. The measurement of volume changes by the shrinkage drains is allowing continuous volume changes to be measured from the beginning of the setting of the concrete. It is possible to capture the entire process of hydration of concrete. The specimens are in the laboratory and in the outdoor environment, so it’s possible to compare values from different environments. The measured results are compared with the calculation models of shrinkage (Model B4 from Bažant [4]; Model Code 2010 [16] and ČSN EN 1992-1-1 [9]).

Mechanomics Approaches to Understand Cell Behavior in Context of Tissue Neogenesis, During Prenatal Development and Postnatal Healing.

Mechanomics represents the natural progression of knowledge at the intersection of mechanics and biology with the aim to codify the role of mechanical environment on biological adaptation. Compared to the mapping of the human genome, the challenge of mapping the mechanome remains unsolved. Solving this grand challenge will require both top down and bottom up R&D approaches using experimental and computational tools to visualize and measure adaptation as it occurs. Akin to a mechanical test of a smart material that changes its mechanical properties and local environment under load, stem cells adapt their shape, cytoskeletal architecture, intrinsic mechanical properties, as well as their own niche, through cytoskeletal adaptation as well as up- and down-regulation of structural proteins that modulate their mechanical milieux. Recent advances in live cell imaging allow for unprecedented study and measurements of displacements, shape and volume changes in stem cells, reconfiguring of cytoskeletal machinery (nucleus, cytoskeleton), in response to controlled mechanical forces and stresses applied at cellular boundaries. Coupled with multiphysics computational and virtual power theoretical approaches, these novel experimental approaches enable mechanical testing of stem cells, multicellular templates, and tissues inhabited by stem cells, while the stem cells themselves evolve over time. The novel approach is paving the way to decipher mechanisms of structural and functional adaptation of stem cells in response to controlled mechanical cues. This mini-review outlines integrated approaches and methodologies implemented to date in a series of studies carried out by our consortium. The consortium’s body of work is described in context of current roadblocks in the field and innovative, breakthrough solutions and is designed to encourage discourse and cross disciplinary collaboration in the scientific community.

The influence of rates of drying and wetting on measurements of soil water retention curves

The water retention curve is fundamental for a comprehensive description of the hydro-mechanical behaviour of unsaturated soils. The water retention testing system developed at Durham University allows direct and continuous measurement of suction using a high capacity tensiometer, water content determined from mass readings of a digital balance and measurements of volume change. The system was modified to accommodate an additional tensiometer to measure suction at the top besides the existing one at the bottom of the soil specimen. Soil specimens were subjected to drying and wetting following two procedures: discrete measurements carried out in stages to ensure equalisation and continuous measurement at different rates. All suctions measured during continuous and discrete measurements were very close at high saturation degrees. At lower saturation degrees, the suction values from the top and bottom of the specimen deviated from suctions observed in discrete measurements. This deviation in suction values was more evident in accelerated drying and wetting patterns. This can be explained by the fact that water permeability reduces with the decrease in saturation levels.

Prolonged treatment planning can increase real rectal dose in 3D brachytherapy for cervical cancer

PurposeThe purpose of this study was to evaluate the influence of 3D brachytherapy planning time on the real dose distribution.Material and methods10 patients with cervical cancer were evaluated using 2 computed tomography (CT) scans brachytherapy. The first scan was performed after the insertion of UVAG applicators, and the second was done after creating the treatment plan, just before the irradiation of first and third fraction. Both plans were compared in terms of changes of volumes and differences in the dose for high-risk organs using GEC-ESTRO Working Group parameters.ResultsThe median planning time was 54 minutes (36-64 minutes). The absolute median change of volume for bladder, rectum, and sigmoid was 32.1 cm3 (1.6-108.6 cm3), 5.6 cm3 (0.4-61.8 cm3), and 8.4 cm3 (0.2-74.1 cm3), respectively. This difference led to an increased dose for bladder and sigmoid for D0.1cc by 46.7 cGy and 25.7 cGy, for D1cc by 59.2 cGy and 11.8 cGy, and for D2cc by 44.7 cGy and 10 cGy, respectively, per each fraction. Measured volume change in case of rectum led to a decreased dose per each fraction for D0.1cc with 7.1 cGy, for D1cc with 3.5 cGy, and for D2cc with 4.8 cGy. We observed that statistically significant dependency between the planning time and the dose was proved for rectum. The longer time for planning, the higher dose for rectum. The correlation coefficient for D0.1cc was 0.6715 (p = 0.0061), for D1cc was 0.6404 (p = 0.011), and for D2cc was 0.5891 (p = 0.0197).ConclusionsExtended treatment planning time for brachytherapy due to the changes in topography of small pelvis can lead to different dose in high-risk organs than previously planned. It seems that the most significant changes are related to rectum.

Generalised boundary shift integral for longitudinal assessment of spinal cord atrophy

Spinal cord atrophy measurements obtained from structural magnetic resonance imaging (MRI) are associated with disability in many neurological diseases and serve as in vivo biomarkers of neurodegeneration. Longitudinal spinal cord atrophy rate is commonly determined from the numerical difference between two volumes (based on 3D surface fitting) or two cross-sectional areas (CSA, based on 2D edge detection) obtained at different time-points. Being an indirect measure, atrophy rates are susceptible to variable segmentation errors at the edge of the spinal cord. To overcome those limitations, we developed a new registration-based pipeline that measures atrophy rates directly. We based our approach on the generalised boundary shift integral (GBSI) method, which registers 2 scans and uses a probabilistic XOR mask over the edge of the spinal cord, thereby measuring atrophy more accurately than segmentation-based techniques. Using a large cohort of longitudinal spinal cord images (610 subjects with multiple sclerosis from a multi-centre trial and 52 healthy controls), we demonstrated that GBSI is a sensitive, quantitative and objective measure of longitudinal spinal cord volume change. The GBSI pipeline is repeatable, reproducible, and provides more precise measurements of longitudinal spinal cord atrophy than segmentation-based methods in longitudinal spinal cord atrophy studies.

Mass balance of the Greenland Ice Sheet from 1992 to 2018.

The Greenland Ice Sheet has been a major contributor to global sea-level rise in recent decades1,2, and it is expected to continue to be so3. Although increases in glacier flow4-6 and surface melting7-9 have been driven by oceanic10-12 and atmospheric13,14 warming, the magnitude and trajectory of the ice sheet's mass imbalance remain uncertain. Here we compare and combine 26 individual satellite measurements of changes in the ice sheet's volume, flow and gravitational potential to produce a reconciled estimate of its mass balance. The ice sheet was close to a state of balance in the 1990s, but annual losses have risen since then, peaking at 345±66billion tonnes per year in 2011. In all, Greenland lost 3,902±342 billion tonnes of ice between 1992 and 2018, causing the mean sea level to rise by 10.8±0.9 millimetres. Using three regional climate models, we show that the reduced surface mass balance has driven 1,964±565 billion tonnes (50.3 per cent) of the ice loss owing to increased meltwater runoff. The remaining 1,938±541 billion tonnes (49.7 per cent) of ice loss was due to increased glacier dynamical imbalance, which rose from 46±37 billion tonnes per year in the 1990s to 87±25 billion tonnes per year since then. The total rate of ice loss slowed to 222±30 billion tonnes per year between 2013 and 2017, on average, as atmospheric circulation favoured cooler conditions15 and ocean temperatures fell at the terminus of Jakobshavn Isbræ16. Cumulative ice losses from Greenland as a whole have been close to the rates predicted by the Intergovernmental Panel on Climate Change for their high-end climate warming scenario17, which forecast an additional 70 to 130 millimetres of global sea-level rise by 2100 compared with their central estimate.

Imprinted plasmonic measuring nanocylinders for nanoscale volumes of materials

Abstract Optical measurement of materials at the nanoscale is important for nanotechnology. Various plasmonic nanorulers have been studied for measuring nanoscale distance and orientation of materials, but they lack the capability to contain and measure nanoscale volumes, especially for liquid or soft materials. Here, we demonstrate the use of imprinted plasmonic volumetric nanocylinders, which act as nanoscale graduated cylinders and facilitate nanomaterial measurement via visible light. Our theoretical and experimental achievements illuminate a promising method for non-destructive, low-cost and fast measurement of material volume changes at the nanoscale, which will benefit the fields of analytical chemistry, nanofabrication and biomedical sensing.

Noninvasive measurement of stroke volume changes in critically ill patients by means of electrical impedance tomography

Previous animal experiments have suggested that electrical impedance tomography (EIT) has the ability to noninvasively track changes in cardiac stroke volume (SV). The present study intended to reproduce these findings in patients during a fluid challenge. In a prospective observational study including critically ill patients on mechanical ventilation, SV was estimated via ECG-gated EIT before and after a fluid challenge and compared to transpulmonary thermodilution reference measurements. Relative changes in EIT-derived cardiosynchronous impedance changes in the heart ([Formula: see text]) and lung region ([Formula: see text]) were compared to changes in reference SV by assessing the concordance rate (CR) and Pearson's correlation coefficient (R). We compared 39 measurements of 20 patients. [Formula: see text] did not show to be a reliable estimate for tracking changes of SV (CR = 52.6% and R = 0.13 with P = 0.44). In contrast, [Formula: see text] showed an acceptable trending performance (CR = 94.4% and R = 0.72 with P < 0.0001). Our results indicate that ECG-gated EIT measurements of [Formula: see text] are able to noninvasively monitor changes in SV during a fluid challenge in critically ill patients. However, this was not possible using [Formula: see text]. The present approach is limited by the influences induced by ventilation, posture or changes in electrode-skin contact and requires further validation.

Robust HU-based CT ventilation from an integrated mass conservation formulation.

Computed tomography (CT) ventilation algorithms estimate volume changes induced by respiratory motion. Existing Hounsfield Unit (HU) methods approximate volume change from the measured HU variations between spatially corresponding voxel locations within a temporally resolved CT image pair, assuming that volume changes are caused solely by changes in air content. Numerical implementations require a deformable image registration to determine the inhale/exhale spatial correspondence, a preprocessing lung volume segmentation, a preprocessing high‐intensity vessel segmentation, and a post‐processing smoothing applied to the raw volume change estimates obtained for each lung tissue voxel.PurposeWe introduce the novel mass‐conserving volume change (MCVC) method for estimating voxel volume changes from the HU values within an inhale/exhale CT image pair. MCVC is based on subregional volume change estimates that possess quantitatively characterized and controllable levels of uncertainty. MCVC is therefore robust to small variations in DIR solutions and the resulting ventilation images are overall more reproducible. In contrast to existing HU methods, MCVC does not require a preprocessing lung vessel segmentation or pre/post‐processing Gaussian smoothing.MethodsSubregional volume change estimates are defined in terms of mean density ratios. As such, the corresponding uncertainty is characterized using Gaussian statistics and standard error analysis of the sample density means. A numerical solution is obtained from the MCVC formulation by solving a constrained linear least squares problem defined by a series of subregional volume change estimates. Reproducibility of the MCVC method with respect to DIR solution was assessed using expert‐determined landmark point pairs and inhale/exhale phases from 10 four‐dimensional CTs (4DCTs) available on http://www.dir-lab.com. MCVC was also compared to the robust Integrated Jacobian Formulation (IJF), a transformation‐based ventilation method.ResultsThe ten Dir‐Lab 4DCT cases were registered twice with the same DIR algorithm, but using different degrees of freedom (DIR 1 and DIR 2). Standard HU ventilation (HUV) and MCVC ventilation images were computed for both solutions. The average spatial errors (300 landmarks per case) for DIR 1 ranged between 0.74 and 1.50 mm, whereas for DIR 2 they ranged between 0.68 and 1.18 mm. Despite the differences in spatial errors between the two DIR solutions, the average Pearson correlation between the corresponding HUV images was 0.94 (0.03), while for the MCVC images it was 1.00 (0.00). The average correlation between MCVC and IJF ventilation over the ten test cases was 0.81 (0.14), whereas for HUV and IJF it was 0.56 (1.11).ConclusionWhile HUV is robust to DIR solution, its implementation depends on heuristic Gaussian smoothing and vessel segmentation. MCVC is based on subregional volume change measurements with quantifiable and controllable levels of uncertainty. The subregional approach eliminates the need for Gaussian smoothing and lung vasculature segmentation. Numerical experiments are consistent with the underlying mathematical theory and indicate that MCVC ventilation is more reproducible with respect to DIR algorithm than standard HU methods. MCVC results are also more consistent with the robust IJF method, which suggests that incorporating robustness leads to more consistent results across both DIRs and ventilation algorithms.

Acceleration of pearlite transformation in a high-carbon steel by uniaxial compressive stress confirmed by volume measurements

Abstract Effect of external stress on pearlite transformation in a high-carbon steel was examined in terms of the measurement of volume change during isothermal holding. Two dimensional measurement of the steel holding at various temperatures under constant stress condition clarified anisotropic transformation plasticity, which means that the volume measurements are necessary to examine the transformation behaviors quantitatively. According to the measurement of volume change, it was found that the larger loading brings the shorter incubation time when compared at the same transformation temperature. These changes can be represented by the Johnson-Mehl-Avrami-Kolmogorov type equation with four constants when the transformation temperature is adequately deviated from the bainite start temperature.

Segmental Intracellular, Interstitial, and Intravascular Volume Changes during Simulated Hemorrhage and Resuscitation: A Case Study.

This paper describes a new combined impedance plethysmographic (IPG) and electrical bioimpedance spectroscopic (BIS) instrument and software that will allow noninvasive real-time measurement of segmental blood flow, intracellular, interstitial, and intravascular volume changes during various fluid management procedures. The impedance device can be operated either as a fixed frequency IPG for the quantification of segmental blood flow and hemodynamics or as a multi-frequency BIS for the recording of intracellular and extracellular resistances at 40 discrete input frequencies. The extracellular volume is then deconvoluted to obtain its intravascular and interstitial component volumes as functions of elapsed time. The purpose of this paper is to describe this instrumentation and to demonstrate the information that can be obtained by using it to monitor segmental compartment volume responses of a pig model during simulated hemorrhage and resuscitation. Such information may prove valuable in the diagnosis and management of rapid changes in the body fluid balance and various clinical treatments.

Measuring Volume Change of Alkali-Activated Slag Pastes in Early Stage by Using Helium Pycnometry

AbstractIn the present study, alkali-activated slag (AAS) pastes were prepared using slag and water glass with different modulus, and the effect of a modulus of water glass on the volume change of ...

Experimental Determination of Early Shrinkage of Alkali-Activated Slag

This paper deals with the relationship between chemical processes in the early stages of hydration of alkali-activated slag, volume changes and the development of the microstructure of this material. Two test pastes were produced for the purpose of the experiment - one with and the other without an organic admixture (isopropyl alcohol). The pastes were used to monitor autogenous shrinkage by measuring volume changes and at the same time the changes in the material during setting and early hardening using a modern ultrasonic instrument Vikasonic. The output of the described experiment is a detailed evaluation of the difference in the behaviour of the used alkali-activated paste with and without the addition of an organic admixture.

Investigation of THF hydrate formation kinetics: Experimental measurements of volume changes

The present study is based on the investigation of hydrate formation and growth of THF through an online and direct method. In fact, the volume rise associated with hydrate formation has been used for kinetics studies. This procedure which is called volumetric method is more precise than the conventional method based on temperature variation. Monitoring the hydrate nucleation using the deviation of volume can be carried out more rapidly, compared to doing so using the temperature variation, especially in the initial hydrate nucleation point. Furthermore, the mole of formed hydrate can be easily estimated by this method. According to this approach, the effect of MCM-41 nanoparticles with a mass/volume fraction of 0.004%, 0.016%, 0.04% and 0.2% on ambient pressure has been studied applying THF hydrate former. The results of temperature and volume variation indicated that the growth of hydrate was enhanced by an increase in the concentration of nanofluid to the specific concentration. Moreover, it was approved that, the volumetric method is more appropriate to identify the kinetics of hydrate nucleation and growth in the presence of additives.

Experimental determination of the influence of additives on shrinkage in self-compacting concrete

The paper deals with the influence of additives on the progress of shrinkage and mass losses in self-compacting concrete. Limestone and fly ash at varying amounts were used as an additive in the production of four types of self-compacting concrete. Volume changes were observed from an early stage of setting (the measurement was commenced within 1 hour of mixing) using shrinkage drains with a moveable wall, followed by a long-term manual measurement using an external strain gauge. For the first 48 hours the volume-change measurement was continuous, and for the next few months it was performed manually. Mass losses were determined simultaneously with shrinkage – during the first 48 hours by weighing on a special weighing table capable of continuous recording, and manually afterwards.

Experimental Measurement of Volume Changes on Cement Concrete Depending on the Subsoil

The paper describes experimental measurement of volume changes of cement concrete elements depending on the subsoil. Volume changes of cement concrete (including shrinkage and swelling) are theoretically known and at present there are many calculation models to determine the final shrinkage at the time of the design of the concrete or construction. The subsoil beneath the concrete structure has a significant effect on the volume changes of the concrete, and this behaviour must be considered when designing. However, the calculation models do not consider the influence of the subsoil and friction effects. The experiment described in the article includes the behaviour of different concretes on differently defined subsoils. At the defined input conditions, volume changes have been measured over the long term in different climatic conditions. The result of the experiment is the values of volume changes, depending on the concrete-subsoil interaction.

Control of Solidification Pattern of Cast Irons by Simultaneous Thermal and Contraction / Expansion Analysis

An experimental device conducts thermal analysis and volume change measurements in a single ceramic cup with cast iron quality as the variable. The recorded data are processed using specialized software. Experiments compare solidification patterns for white [WI], grey [GI] and ductile [DI] irons, to correlate the most important events between the cooling curves and contraction curves, to evaluate the sensitivity to shrinkage formation. All of the irons have similar values for initial expansion up to the start of eutectic freezing [0.437 – 0.443%]. Graphite formation promotes expansion [WI-0.002%, GI-0.109%, DI-0.596%], resulting a difference in the reached maximum expansion [WI-0.465%, GI-0.552%, DI-1.032%], placed between the end of eutectic recalescence and the end of solidification. Higher graphite expansion, greater the shrinkage sensitivity: open shrinkage increased while the density of a casting when considering total shrinkage and micro-shrinkage formation decreased. Prolonged graphitization at the beginning of eutectic reaction increased the expansion and, consequently, shrinkage sensitiveness. More graphite formation at the end of this stage also increased expansion, but this phenomena contributed to reduce of shrinkage level, due to the better access of liquid iron to compensate contraction holes. Special metallurgical treatments can favour a strong graphitization process at the end of solidification, with beneficial effects on the castings soundness.

The measurement of volume change by capillary dilatometry.

Capillary dilatometry enables direct measurement of changes in volume, an extensive thermodynamic property. The results provide insight into the changes in hydration that occur upon protein folding, ligand binding, and the interactions of proteins with nucleic acids and other cellular components. Often the entropy change arising from release of hydrating solvent provides the main driving force of a binding reaction. For technical reasons, though, capillary dilatometry has not been as widely used in protein biochemistry and biophysics as other methods such as calorimetry. Described here are simple apparatus and simple methods, which bring the technique within the capacity of any laboratory. Even very simple results are shown to have implications for macromolecular‐based phenomena. Protein examples are described.

The current gold standard breast volumetry technique seems to overestimate fat graft volume retention in the breast: A validation study

MRI is generally considered as the gold standard for measuring breast volume because of its high accuracy of the modality. Many techniques used to measure total breast volume have been validated, but none of these techniques have been validated for their ability to measure the volume retention of fat grafts in the breast. In this study, the authors investigated the accuracy of the most common MRI technique used to measure fat graft retention in the breast by measuring the volume changes after breast augmentation. Patients undergoing breast augmentation with either breast implants or fat grafting underwent MRI scans before and after surgery. Blinded observers measured the change in breast volume from the MRI scans. The difference between the measured change in breast volume and the volume of the breast augmentation was used to determine the accuracy of the MRI technique. Twenty-eight patients with a total of 56 breasts were included. In total, 168 measurements of change in breast volume were performed by the observers. The MRI measurements of change in breast volume overestimated the true volumes of the breast augmentations by an average of 50.8%, and only 8 of the 168 individual measurements had measurement errors below 50 mL. The MRI technique, which is considered as the gold standard for the quantification of fat graft volume retention, was associated with a significant measurement error. These findings have potential implications for the interpretation of previously published results of studies based on this technique.