Positive Volume Change Research Articles

Lysozyme Stabilization under High Pressure: Differential Scanning Microcalorimetry

The heat denaturation of lysozyme has been studied by high-pressure differential scanning microcalorimetry. It has been demonstrated that an increase in pressure has different influence on denaturation temperature and enthalpy at different pH values. It has been established that the pressure increase has no appreciable effect on the transition cooperativity. The experimental data have been analyzed using an equilibrium model of transition between two states. Partial molar volume changes accompanying the denaturation as well as isothermal compressibility and thermal expansibility coefficients have been assessed. In contrast to the denaturation of most globular proteins, the lysozyme denaturation under conditions of the experiment was accompanied by positive volume changes. Possible reasons for this unusual behavior have been discussed.

Dependence of Cell Failure on Cut-Off Voltage Ranges and Observation of Kinetic Hindrance in LiNi0.8Co0.15Al0.05O2

The dependence of differential capacity versus voltage (dQ/dV) of Li/NCA half cells on temperature and testing current (C-rate) was studied. Kinetic hindrance of lithium diffusion at both low (∼3.5 V vs Li/Li+) and high states of charge (∼4.17 V) was observed. In-situ X-ray diffraction measured the volume changes of the NCA lattice versus state of charge. NCA/graphite pouch cells were cycled in various voltage ranges to explore the impacts of depth of discharge (DOD) ranges and the kinetic hindrance regions in NCA on cell failure. dV/dQ analysis, full cell impedance and symmetric cell impedance analysis as well as half-cell studies of recovered electrodes were performed after 0, ∼400 and 800 charge-discharge cycles. The contributions of active mass loss and shift loss (from loss of Li inventory) to the capacity fade of NCA/graphite cells under various testing conditions were determined. The increase in positive electrode charge transfer impedance with cycle number was proportional to the increase of positive electrode active mass loss. There was no strong correlation between positive electrode active mass loss and lattice volume change. NCA active mass loss during cycling can be minimized when the dQ/dV peaks at ∼3.5 and 4.17 V (vs. Li/Li+), that show kinetic hindrance, are partially or completely avoided.

Microscale characterization of rupture nucleation unravels precursors to faulting in rocks

Precursory signals, manifestations of microscale damage that precedes dynamic faulting, are key to earthquake forecasting and risk mitigation. Detections of precursors have primarily relied on measurements performed using sensors installed at some distance away from the rupture area in both field and laboratory experiments. Direct observations of continuous microscale damage accumulated during fault nucleation and propagation are scarce. Using an X-ray transparent triaxial deformation apparatus, we show the first quantitative high resolution three-dimensional (3D) information about damage evolution of rocks undergoing brittle failure. The dynamic microtomography images documented a spectrum of damage characteristics and different fault growth patterns. The interplay between various deformation mechanisms can result in either a positive, negative, or constant net volume change. Consequently, changes in rock density and acoustic wave velocities before faulting are expected to vary in different tectonics settings, hence making failure forecasting intrinsically dependent on rock type at depth.

Reaction-induced grain boundary cracking and anisotropic fluid flow during prograde devolatilization reactions within subduction zones

Devolatilization reactions during prograde metamorphism are a key control on the fluid distribution within subduction zones. Garnets in Mn-rich quartz schist within the Sanbagawa metamorphic belt of Japan are characterized by skeletal structures containing abundant quartz inclusions. Each quartz inclusion was angular-shaped, and showed random crystallographic orientations, suggesting that these quartz inclusions were trapped via grain boundary cracking during garnet growth. Such skeletal garnet within the quartz schist formed related to decarbonation reactions with a positive total volume change (∆V t > 0), whereas the euhedral garnet within the pelitic schists formed as a result of dehydration reaction with negative ∆V t values. Coupled hydrological–chemical–mechanical processes during metamorphic devolatilization reactions were investigated by a distinct element method (DEM) numerical simulation on a foliated rock that contained reactive minerals and non-reactive matrix minerals. Negative ∆V t reactions cause a decrease in fluid pressure and do not produce fractures within the matrix. In contrast, a fluid pressure increase by positive ∆V t reactions results in hydrofracturing of the matrix. This fracturing preferentially occurs along grain boundaries and causes episodic fluid pulses associated with the development of the fracture network. The precipitation of garnet within grain boundary fractures could explain the formation of the skeletal garnet. Our DEM model also suggests a strong influence of reaction-induced fracturing on anisotropic fluid flow, meaning that dominant fluid flow directions could easily change in response to changes in stress configuration and the magnitude of differential stress during prograde metamorphism within a subduction zone.

Origin of peraluminous minerals (corundum, spinel, and sapphirine) in a highly calcic anorthosite from the Sittampundi Layered Complex, Tamil Nadu, India

The highly calcic anorthosite (An>95) from the Sittampundi Layered Complex (SLC) develops corundum, spinel and sapphirine that are hitherto not reported from any anorthositic rocks in the world. Petrological observations indicate the following sequence of mineral growth: plagioclasematrix → corundum; clinopyroxene → amphibole; corundum + amphibole → plagioclasecorona + spinel; and spinel + corundum → coronitic sapphirine. Phase relations in the CaO–Na2O–Al2O3–SiO2–H2O (CNASH) system suggest that corundum was presumably developed through vapour present incongruent melting of the highly calcic plagioclase during ultra-high temperature (UHT) metamorphism (T ≥ 1000 °C, P ≥ 9 kbar). Topological constraints in parts of the Na2O–CaO–MgO–Al2O3–SiO2–H2O (NCMASH) system suggest that subsequent to the UHT metamorphism, aqueous fluid(s) permeated the rock and the assemblage corundum + amphibole + anorthite + clinozoisite was stabilized during high-pressure (HP) metamorphism (11 ± 2 kbar, 750 ± 50 °C). Constraints of the NCMASH topology and thermodynamic and textural modeling study suggest that coronitic plagioclase and spinel formed at the expense of corundum + amphibole during a steeply decompressive retrograde P–T path (7–8 kbar and 700–800 °C) in an open system. Textural modeling studies combined with chemical potential diagrams (μSiO2–μMgO) in the MASH system support the view that sapphirine also formed from due to silica and Mg metasomatism of the precursor spinel ± corundum, on the steeply decompressive retrograde P–T path, prior to onset of significant cooling of the SLC. Extremely channelized fluid flow and large positive solid volume change of the stoichiometrically balanced sapphirine forming reaction explains the localized growth of sapphirine.

Metabolic enzyme activities of abyssal and hadal fishes: pressure effects and a re-evaluation of depth-related changes

Metabolic enzyme activities of muscle tissue have been useful and widely-applied indicators of whole animal metabolic capacity, particularly in inaccessible systems such as the deep sea. Previous studies have been conducted at atmospheric pressure, regardless of organism habitat depth. However, maximum reaction rates of some of these enzymes are pressure dependent, complicating the use of metabolic enzyme activities as proxies of metabolic rates. Here, we show pressure-related rate changes in lactate and malate dehydrogenase (LDH, MDH) and pyruvate kinase (PK) in six fish species (2 hadal, 2 abyssal, 2 shallow). LDH maximal reaction rates decreased with pressure for the two shallow species, but, in contrast to previous findings, it increased for the four deep species, suggesting evolutionary changes in LDH reaction volumes. MDH maximal reaction rates increased with pressure in all species (up to 51±10% at 60MPa), including the tide pool snailfish, Liparis florae (activity increase at 60MPa 44±9%), suggesting an inherent negative volume change of the reaction. PK was inhibited by pressure in all species tested, including the hadal liparids (up to 34±3% at 60MPa), suggesting a positive volume change during the reaction. The addition of 400mM TMAO counteracted this inhibition at both 0.5 and 2.0mM ADP concentrations for the hadal liparid, Notoliparis kermadecensis. We revisit depth-related trends in metabolic enzyme activities according to these pressure-related rate changes and new data from seven abyssal and hadal species from the Kermadec and Mariana trenches. Results show that, with abyssal and hadal species, pressure-related rate changes are another variable to be considered in the use of enzyme activities as proxies for metabolic rate, in addition to factors such as temperature and body mass. Intraspecific increases in tricarboxylic acid cycle enzymes with depth of capture, independent of body mass, in two hadal snailfishes suggest improved nutritional condition for individuals deeper in the hadal zone, likely related to food availability. These new data inform the discussion of factors controlling metabolism in the deep sea, including the visual interactions hypothesis and extend published trends to the planet's deepest-living fishes.

Modulation of the Thermodynamic Signatures of an RNA Thermometer by Osmolytes and Salts

Folding of ribonucleic acids (RNAs) is driven by several factors, such as base pairing and stacking, chain entropy, and ion-mediated electrostatics, which have been studied in great detail. However, the power of background molecules in the cellular milieu is often neglected. Herein, we study the effect of common osmolytes on the folding equilibrium of a hairpin-structured RNA and, using pressure perturbation, provide novel thermodynamic and volumetric insights into the modulation mechanism. The presence of TMAO causes an increased thermal stability and a more positive volume change for the helix-to-coil transition, whereas urea destabilizes the hairpin and leads to an increased expansibility of the unfolded state. Further, we find a strong interplay between water, salt, and osmolyte in driving the thermodynamics and defining the temperature and pressure stability limit of the RNA. Our results support a universal working mechanism of TMAO and urea to (de)stabilize proteins and the RNA.

Modulation of the Thermodynamic Signatures of an RNA Thermometer by Osmolytes and Salts

AbstractFolding of ribonucleic acids (RNAs) is driven by several factors, such as base pairing and stacking, chain entropy, and ion‐mediated electrostatics, which have been studied in great detail. However, the power of background molecules in the cellular milieu is often neglected. Herein, we study the effect of common osmolytes on the folding equilibrium of a hairpin‐structured RNA and, using pressure perturbation, provide novel thermodynamic and volumetric insights into the modulation mechanism. The presence of TMAO causes an increased thermal stability and a more positive volume change for the helix‐to‐coil transition, whereas urea destabilizes the hairpin and leads to an increased expansibility of the unfolded state. Further, we find a strong interplay between water, salt, and osmolyte in driving the thermodynamics and defining the temperature and pressure stability limit of the RNA. Our results support a universal working mechanism of TMAO and urea to (de)stabilize proteins and the RNA.

A volumetric approach: Interactions of some local anesthetical drugs with α-cyclodextrin in aqueous solutions at 298.15 K

The density measurements have been carried out for ternary aqueous solutions containing a fixed concentration (∼0.1mol·kg−1) of α-cyclodextrin (α-CD) and varying concentrations (∼0.003 to ∼0.21mol·kg−1) of some local anesthetical drugs, namely procaine hydrochloride (PC·HCl), lidocaine hydrochloride monohydrate (LC·HCl) and tetracaine hydrochloride (TC·HCl) at 298.15K. The density data are used to determine apparent molar volumes of the drug molecules in ternary solutions at finite concentrations (ϕV) as well at infinitely dilute solutions (ϕV0). Following the methods developed by Høiland et al. as well by Jolicoeur et al. and using the infinite dilution volume values for the drugs in ternary and binary solutions and incorporating the equilibrium constant values for the complexation between α-CD and drugs, volume changes due to encapsulation or complexation have been estimated. It is observed that all the studied hydrochlorides exhibit high positive volume change due to complexation. The results are discussed in terms of host-guest interaction and structural specificity of guest molecules.

Bedside assessment of the effects of positive end-expiratory pressure on lung inflation and recruitment by the helium dilution technique and electrical impedance tomography.

Higher positive end-expiratory pressure might induce lung inflation and recruitment, yielding enhanced regional lung protection. We measured positive end-expiratory pressure-related lung volume changes by electrical impedance tomography and by the helium dilution technique. We also used electrical impedance tomography to assess the effects of positive end-expiratory pressure on regional determinants of ventilator-induced lung injury. A prospective randomized crossover study was performed on 20 intubated adult patients: 12 with acute hypoxemic respiratory failure and 8 with acute respiratory distress syndrome. Each patient underwent protective controlled ventilation at lower (7 [7, 8] cmH2O) and higher (12 [12, 13] cmH2O) positive end-expiratory pressures. At the end of each phase, we collected ventilation, helium dilution, and electrical impedance tomography data. Positive end-expiratory pressure-induced changes in lung inflation and recruitment measured by electrical impedance tomography and helium dilution showed close correlations (R (2)=0.78, p<0.001 and R (2)=0.68, p<0.001, respectively) but with relatively variable limits of agreement. At higher positive end-expiratory pressure, recruitment was evident in all lung regions (p<0.01) and heterogeneity of tidal ventilation distribution was reduced by increased tidal volume distending the dependent lung (p<0.001); in the non-dependent lung, on the other hand, compliance decreased (p<0.001) and tidal hyperinflation significantly increased (p<0.001). In the subgroup of ARDS patients (but not in the whole study population) tidal hyperinflation in the dependent lung regions decreased at higher positive end-expiratory pressure (p=0.05), probably indicating higher potential for recruitment. Close correlations exist between bedside assessment of positive end-expiratory pressure-induced changes in lung inflation and recruitment by the helium dilution and electrical impedance tomography techniques. Higher positive end-expiratory pressure exerts mixed effects on the regional determinants of ventilator-induced lung injury; these merit close monitoring.

Deformations of geosynthetic reinforced soil under bridge service loads

This paper evaluates the results of 13 large scale Geosynthetic Reinforced Soil (GRS) column load tests, also known as performance tests (PT) or mini-pier tests, to study the effect of tensile strength (Tf), vertical reinforcement spacing (Sv), facing elements, and backfill properties on the deformations of GRS at 200 kPa, typical bridge bearing pressures, and also at 400 kPa. The results indicate that GRS performs well under service conditions. A semi-empirical expression is proposed for prescribed bearing pressures to limit vertical strain to 0.5% of the abutment height. In addition, recommendations for estimating lateral deformation for GRS bridge abutments are also provided. At 200 kPa surcharge for this series of tests, vertical settlements ranged from 8.3 to 33.9 mm (or from 0.4% to 1.7% axial strain); lateral deformations ranged from 3.0 mm to 10.1 mm (or 0.6%–2.0% lateral strain); and reinforcement strain ranged from less than 1% during construction to less than 3% during loading. The lateral deformation results indicate that the maximum displacement occurs in the top third region of the wall face. Comparing the vertical and lateral displacement data shows that most GRS models experienced negligible positive volume changes up to about 1% under typical bridge service loads.

Volume profile of α-chymotrypsin during adsorption and enzymatic reaction on a poly(acrylic acid) brush.

Poly(acrylic acid) (PAA) brushes are known to provide a native-like environment for proteins. In this study, we explore this biocompatibility under high pressure conditions. Using α-chymotrypsin (α-CT) as a model enzyme, we report on the pressure dependencies of the enzymatic activity and the neutron scattering length density profile, when this enzyme is adsorbed on a PAA brush. From high pressure total internal reflection fluorescence spectroscopy, an increasing enzymatic activity has been observed up to 1000 bar, but a rather pressure independent enzymatic activity at higher pressures up to 2000 bar. This finding suggests a non-constant activation volume of α-CT on the PAA brush that is negative below 1000 bar. Thus, the compact nature of the transition state of α-CT is largely preserved upon adsorption. We have also performed high pressure neutron reflectivity experiments to determine the spatial distribution of α-CT inside the PAA brush. Apparently, the enzyme is strongly binding to the PAA chains with 2.3 mg m(-2) of adsorbed enzyme that is reduced to about 1.7 mg m(-2) at 1000-2000 bar. This change of adsorbed mass is consistent with a positive volume change of adsorption, which is probably reflecting electrostriction upon protein-PAA interaction. Thus, the performed high pressure experiments provide new insights into the volume profile of α-CT during adsorption and enzymatic activity on the PAA brush. They also demonstrate that the biocompatible properties of a PAA brush can even be enhanced by pressure.

Applications of pressure perturbation calorimetry to study factors contributing to the volume changes upon protein unfolding

BackgroundPressure perturbation calorimetry (PPC) is a biophysical method that allows direct determination of the volume changes upon conformational transitions in macromolecules. Scope of this reviewThis review provides novel details of the use of PPC to analyze unfolding transitions in proteins. The emphasis is made on the data analysis as well as on the validation of different structural factors that define the volume changes upon unfolding. Four case studies are presented that show the application of these concepts to various protein systems. Major conclusionsThe major conclusions are:1.Knowledge of the thermodynamic parameters for heat induced unfolding facilitates the analysis of the PPC profiles.2.The changes in the thermal expansion coefficient upon unfolding appear to be temperature dependent.3.Substitutions on the protein surface have negligible effects on the volume changes upon protein unfolding.4.Structural plasticity of proteins defines the position dependent effect of amino acid substitutions of the residues buried in the native state.5.Small proteins have positive volume changes upon unfolding which suggests difference in balance between the cavity/void volume in the native state and the hydration volume changes upon unfolding as compared to the large proteins that have negative volume changes. General significanceThe information provided here gives a better understanding and deeper insight into the role played by various factors in defining the volume changes upon protein unfolding. This article is part of a Special Issue entitled Microcalorimetry in the BioSciences — Principles and Applications, edited by Fadi Bou-Abdallah.

Experimental study of the replacement of calcite by calcium sulphates

Among the most relevant mineral replacement reactions are those involving sulphates and carbonates, which have important geological and technological implications. Here it is shown experimentally that during the interaction of calcite (CaCO3) cleavage surfaces with sulphate-bearing acidic solutions, calcite is ultimately replaced by gypsum (CaSO4 2H2O) and anhydrite (CaSO4), depending on the reaction temperature. Observations suggest that this occurs most likely via an interface-coupled dissolution–precipitation reaction, in which the substrate is replaced pseudomorphically by the product. At 120 and 200°C gypsum and/or bassanite (CaSO4·0.5H2O) form as precursor phases for the thermodynamically stable anhydrite. Salinity promotes the formation of less hydrated precursor phases during the replacement of calcite by anhydrite. The reaction stops before equilibrium with respect to calcite is reached and during the course of the reaction most of the bulk solutions are undersaturated with respect to the precipitating phase(s). A mechanism consisting of the dissolution of small amounts of solid in a thin layer of fluid at the mineral–fluid interface and the subsequent precipitation of the product phase from this layer is in agreement with these observations. PHREEQC simulations performed in the framework of this mechanism highlight the relevance of transport and surface reaction kinetics on the volume change associated with the CaCO3–CaSO4 replacement. Under our experimental conditions, this reaction occurs with a positive volume change, which ultimately results in passivation of the unreacted substrate before calcite attains equilibrium with respect to the bulk solution.

A combined phase field approach for martensitic transformations and damage

A combined continuum phase field model for martensitic transformations and fracture is introduced. The positive volume change that accompanies the phase transformation from austenite to martensite leads to an eigenstrain within the martensitic phase, which is considered within the present approach. Since the eigenstrain leads to both tensile and compressive loads, the model accounts for the sign of the local volume change. With aid of this model, the interactions between microcrack propagation and the formation of the martensitic phase are studied in two dimensions. Martensite forms in agreement with experimental observations at the crack tip and thus influences the crack formation. The numerical implementation is performed with finite elements. For the transient terms, an implicit time integration scheme is employed.

Design, Fabrication, and Characterization of Liquid Metal Microheaters

This paper reports design, fabrication, and characterization of liquid metal-based microheaters. Liquid metal microheaters designed via finite element simulation were fabricated by simply injecting eutectic gallium indium into polydimethylsiloxane (PDMS) microfluidic chips bonded to either silicon or PDMS substrates. Considering the net positive volume change of the microheater upon heating, both nonpressurized and pressurized contacts between the power supply and the liquid metal wires were investigated. The pressurized contact was found to provide more reliable electrical connection, thus more stable long-term operation than the nonpressurized contact. Due to higher thermal conductivity, liquid metal microheaters with silicon substrate exhibit better temperature uniformity than ones with PDMS substrate. However, liquid metal microheaters with PDMS substrate are flexible and deformable, thus more suitable than ones with silicon substrate when microheaters should be applied to nonflat objects.

Microstructure and texture evolution during growth of magnesio-aluminate spinel at corundum-periclase interfaces under uniaxial load: The effect of stress concentration on reaction progress

Reaction rims of magnesio-aluminate spinel were grown at the contacts between periclase and corundum at temperatures of 1250 °C to 1350 °C and under uniaxial load of 0.026 and 0.26 kN per 9 mm² of initial contact area. Single crystals of periclase with [100] and of corundum with [0001] perpendicular to the polished reaction interface as well as polycrystalline corundum were used as starting materials. Immediate application of the load before heating resulted in deformation twinning and fracturing of corundum introducing stress concentration and lateral variations in the quality of physical contact at the reaction interface. The tight contacts are characterized by enhanced reaction progress which together with the positive volume change of the reaction and limits on plasticity of the studied phases led to the opening of void spaces along the reaction interface and large lateral variations in rim thickness occur. Spinel shows strong topotactic relations to the reactant phases including full topotaxy between spinel and periclase, partial topotaxy with (111)_spi‖(0001)_cor and {101}_spi‖{10-10}_cor, and axiotaxy with (111)_spi‖(0001)_cor between spinel and corundum. Oriented nucleation and selective growth were the main mechanism of texture formation. Stress concentrations and tight physical contacts across the reaction interface may enhance nucleation of topotactic grains. The respective spinel–periclase and spinel–corundum reaction interfaces are mostly semi-coherent with sets of line dislocations accounting for the lattice misfit. The systematic occurrence of porosity along the semi-coherent and its absence along the incoherent sections of the spinel–periclase interface reflect the different capacities of the (semi)-coherent and incoherent interface sections for annihilating the vacancies that were emitted from the advancing spinel–periclase reaction interface.

Smart hydrogels exhibiting UCST-type volume changes under physiologically relevant conditions

Hydrogels composed of poly(allylurea) copolymers exhibited rapid temperature positive volume changes without hysteresis under physiologically relevant conditions.

Self-organizing thermal fluid flow in fractured crystalline rock: a geochemical and theoretical approach to evaluating fluid flow in the southern Idaho batholith, USA

Thermal springs in the Idaho batholith (USA) discharge at discrete locations along a 50+ km reach of the Middle Fork of the Boise River (MFBR). Recharge water flows through Basin and Range extension fractures where it is heated by the geothermal gradient and ultimately discharges from the damage zone of the trans-Challis faults located near the bottom of the MFBR. Stable isotopes of water, 14C groundwater ages, fracture and fault orientations, fracture volume changes due to chemical evolution, and recharge area calculations suggest that the thermal springs issue from individual hydrothermal systems and that they are self-organizing. Water evolves chemically along flow paths, dissolving feldspars and precipitating secondary minerals. Secondary minerals accumulate in less-efficient fractures and are flushed from the more efficient ones. Flow-area calculations using heat-flow, exponential decay-of-porosity, and curve-intersection methods show that many of the thermal systems extend beyond their immediate topographic watershed, and that some capture water from adjacent watersheds. Geochemical/flow feedback loops that provide a mechanism for self-organization are modeled using PHREEQC, and positive and negative fracture volume changes are calculated. Criteria for identifying self-organizing granitoid thermal groundwater systems are suggested.

Composition change of the near-surface layer of Li2TiO3 after CO2 absorption observed with accelerator analyses

Non-Rutherford backscattering spectroscopy (NRBS), which allows for a greatly enhanced cross section for scattering, was used to analyze the atomic composition of Li-containing blanket material, 2.6-MeV proton beams were used as the probe beam to profile the atomic composition in the near-surface region down to about 2μm.Li2TiO3 ceramics samples of various densities were exposed to CO2 gas at a pressure of 1atm at room temperature in a glove box. The absorption of CO2 was observed to result in the formation of Li2CO3 on these samples in the NRBS spectra. In low and medium density samples, the density ratio of the absorbed CO2 to Li2TiO3 reached 0.5 after 1800h and CO2 absorption showed a saturation tendency of about 1400h.Li2TiO3 structures without CO2 were recovered by heating samples to 973K, with a residual positive volume change of 10%. The structure appeared to have increased capacity for CO2 absorption with an expanded near-surface layer. This characteristic could present a problem in the process of tritium recovery from the blanket materials.