Water-ice Transition Research Articles

The Possibility of Estimating the Permafrost’s Porosity In Situ in the Hydrocarbon Industry and Environment

Global warming firstly influences the permafrost regions where numerous and rich world hydrocarbon deposits are located. Permafrost thawing has caused severe problems in exploring known hydrocarbon deposits and searching for new targets. This process is also dangerous for any industrial and living regions in cold regions. Knowledge of permafrost’s ice and unfrozen water content is critical for predicting permafrost behavior during the water–ice transition. This is especially relevant when ice and permafrost are melting in many regions under the influence of global warming. It is well known that only part of the formation’s pore water turns into ice at 0 °C. After further lowering the temperature, the water phase transition continues, but at gradually decreasing rates. Thus, the porous space is filled with ice and unfrozen water. Laboratory data show that frozen formations’ mechanical, thermal, and rheological properties strongly depend on the moisture content. Hence, porosity and temperature are essential parameters of permafrost. In this paper, it is shown that by combining research in three fields, (1) geophysical exploration, (2) numerical modeling, and (3) temperature logging, it is possible to estimate the porosity of permafrost in situ. Five examples of numerical modeling (where all input parameters are specified) are given to demonstrate the procedure. This investigation is the first attempt to quantitatively analyze permafrost’s porosity in situ.

Characterization of Water Structure and Phase Behavior within Metal-Organic Nanotubes.

Water behavior under nanoconfinement varies significantly from that in the bulk but also depends on the nature of the pore walls. Hybrid compound offers the ideal system to explore water behavior in complex materials, so a model metal-organic nanotube (UMONT) material was utilized to explore the behavior of water between 100 and 293 K. Single-crystal X-ray and neutron diffraction revealed the formation of a filled Ice-I arrangement that was previously predicted to only occur under high pressures. 17O NMR spectra suggest that the onset of melting for the water in the UMONT channels occurs at 98 K and the presence of ice-like water up to 293 K, indicating that the complete ice-water transition does not occur before dehydration of the material. Overall, the water behavior differs significantly from hydrophobic single-walled carbon nanotubes indicating precise control over water can be achieved through rational design of hybrid materials.

Distribution of unfrozen water and heat transfer mechanism during thawing of liquid nitrogen immersed coal

The content and distribution of pore unfrozen water directly reflect the coal thawing process. It is the key to break through the evolution of coal pore structure under low temperature to study the pore ice melting speed. Taking bituminous coal in Yuan Zhuang, China as the research object, this paper studied pore thawing characteristics of coal samples with different liquid nitrogen freezing time through nuclear magnetic resonance technology. The experimental results clearly demonstrate that appropriate liquid nitrogen freezing time could greatly expand the macropore of bituminous coal, while the expansion effect of micropore and mesopore was less affected by the freezing time. As the freezing time increased, the pores and pore throats of saturated bituminous coal underwent two phases of ice-water transition expansion and liquid nitrogen low-temperature shrinkage. There were differences in the local thermal conductivity of coal samples with different liquid nitrogen freezing time, resulting in different thawing speeds of pore water at the same thawing temperature. When the freezing time increased, the thermal conductivity of coal samples increased due to the pore freezing shrinkage, which can greatly improve the thawing speed of coal samples.

Attenuated Total Reflection at THz Wavelengths: Prospective Use of Total Internal Reflection and Polariscopy

Capabilities of the attenuated total reflection (ATR) at THz wavelengths for increased sub-surface depth characterisation of (bio-)materials are presented. The penetration depth of a THz evanescent wave in biological samples is dependent on the wavelength and temperature and can reach 0.1–0.5 mm depth, due to the strong refractive index change ∼0.4 of the ice-water transition; this is quite significant and important when studying biological samples. Technical challenges are discussed when using ATR for uneven, heterogeneous, high refractive index samples with the possibility of frustrated total internal reflection (a breakdown of the ATR reflection mode into transmission mode). Local field enhancements at the interface are discussed with numerical/analytical examples. Maxwell’s scaling is used to model the behaviour of absorber–scatterer inside the materials at the interface with the ATR prism for realistic complex refractive indices of bio-materials. The modality of ATR with a polarisation analysis is proposed, and its principle is illustrated, opening an invitation for its experimental validation. The sensitivity of the polarised ATR mode to the refractive index between the sample and ATR prism is numerically modelled and experimentally verified for background (air) spectra. The design principles of polarisation active optical elements and spectral filters are outlined. The results and proposed concepts are based on experimental conditions at the THz beamline of the Australian Synchrotron.

Should a hotter paramagnet transform quicker to a ferromagnet? Monte Carlo simulation results for Ising model.

For quicker formation of ice, before inserting inside a refrigerator, heating up of a body of water can be beneficial. We report first observation of a counterpart of this intriguing fact, referred to as the Mpemba effect (ME), during ordering in ferromagnets. By performing Monte Carlo simulations of a generic model, we have obtained results on relaxation of systems that are quenched to sub-critical state points from various temperatures above the critical point. For a fixed final temperature, a system with higher starting temperature equilibrates faster than the one prepared at a lower temperature, implying the presence of ME. The observation is extremely counter-intuitive, particularly because of the fact that the model has no in-built frustration or metastability that typically is thought to provide ME. Via the calculations of nonequilibrium properties concerning structure and energy, we quantify the role of critical fluctuations behind this fundamental as well as technologically relevant observation.

Elastic anisotropy, permeability, and freeze-thaw cycling of rapakivi granite

Due to the ice-water transition, frost weathering in cold regions has always been in focus as a rock deterioration mechanism. Internal stresses, developed by this process, conduce to progressive fracturing and consequent changes in rock properties, particularly, elastic velocities. Previous research was mainly focused on isotropic properties of rocks. However, we have found that elastic anisotropy is substantially enhanced by frost weathering. A series of freeze-thaw tests were performed on weathered rapakivi granite fully saturated by water. The experimental basis involved: a neutron diffraction study of texture, measurements of the 3D distributions of ultrasonic P-wave velocities, and permeability at atmospheric and high confining pressures. Experimental data, along with texture-based effective media modeling of rock elastic properties, revealed the anisotropic response of elastic velocities to freeze-thaw cycling, which is related to the volume increase of specifically oriented cracks. Through permeability measurements, these oriented cracks were determined to be hydraulically interconnected and also responsible for observed frost weathering deterioration. Both ultrasonic and permeability experiments suggested a decrease in the crack closing pressure due to freeze thaw cycling.

Investigation on frost heave of saturated–unsaturated soils

Frost heave is a process of coupled heat–water–mechanics, which refers to heat transfer, water migration, water–ice phase change, deformation, etc. The mechanism of the frost heave for saturated–unsaturated soils was investigated to establish a frost heave model. As the freezing continues, for saturated soils, because all pores are filled with pore water, the total increased volume due to water migration and water crystallization will separate soil particles and induce frost heave. For unsaturated soils, because of the existence of unsaturated pores, volume expansion generates by water and vapor migration and water–ice transition will firstly fill into the unsaturated pores until a critical state is reached. After that, further increased volume will separate soil particles and induce frost heave. Therefore, effective strain ratio was introduced to establish the relationship between frost heave strain of unsaturated soils and the fields of moisture and temperature. Tests were carried out for silty soil. Then, based on the inverse theory, a simplified criterion was proposed to determine the effective strain ratio, and the effective strain ratio was back-calculated according to the test results. Finally, an innovative universal frost heave model for saturated–unsaturated soils was proposed.

Well drilling in permafrost regions: dynamics of the thawed zone

In the cold regions, warm mud is usually used to drill deep wells. This mud causes formation thawing around wells, and as a rule is an uncertain parameter. For frozen soils, ice serves as a cementing material, so the strength of frozen soils is significantly reduced at the ice–water transition. If the thawing soil cannot withstand the load of overlying layers, consolidation will take place, and the corresponding settlement can cause significant surface shifts. Therefore, for long-term drilling or oil/gas production, the radius of thawing should be estimated to predict platform stability and the integrity of the well. It is known that physical properties of formations are drastically changed at the thawing–freezing transition. When interpreting geophysical logs, it is therefore important to know the radius of thawing and its dynamics during drilling and shut-in periods. We have shown earlier that for a cylindrical system the position of the phase interface in the Stefan problem can be approximated through two functions: one function determines the position of the melting-temperature isotherm in the problem without phase transitions, and the second function does not depend on time. For the drilling period, we will use this approach to estimate the radius of thawing. For the shut-in period, we will utilize an empirical equation based on the results of numerical modelling.

The effect of cryogenic suction on the monitoring data of ice barrier formation in a porous water-saturated soil

Artificial ice wall formation is one of the most frequently used techniques for waterproofing of mineshafts constructed in water-saturated rock massifs. In this work, we have developed a complex monitoring system for control of formation of ice. The system includes hydro-observation and temperature monitoring wells combined with simulation module. At the beginning of the monitoring process, we observed contradictory indications of ice wall closing moment by hydro-observation and temperature monitoring subsystems. To explain this effect we introduced in the simulation module two models of ground freezing, which consider the key effects observed under the phase transition in a saturated soil. There are existing of nonequilibrium moisture content in the soil at negative temperatures, kinetic peculiarities of water-ice transition in a porous medium and redistribution of moisture in partially saturated soil. Based on the detail simulation model we have shown that moisture content inside the closed ice wall can decrease due to water migration towards the phase transition front, which, consequently, slows down the water level in hydro-observation wells.

The effect of thermal properties changing (at ice-water transition) on the radius of permafrost thawing

Earlier we developed an approximate method of calculating the radius of permafrost thawing by a cylindrical source with a constant temperature. In this study, we show that the effect of thermal properties changing at the ice-water transition on the radius of thawing in many cases can be neglected. Two typical examples are presented.

The deep-seated lowland relict permafrost from the Suwałki region (NE Poland) – analysis of conditions of its development and preservation

The Udryn PIG 1 research borehole drilled in northeastern Poland (54°14’49”N, 23°03’29”E, 223 m a.s.l.) revealed a permafrost layer, at least 93 m thick, within the sedimentary succession below a depth of 357 m. The base of the permafrost has not been reached at 450 m depth, where the drilling stopped, so its total present thickness remains unknown. The relict permafrost, unexpected in this part of Central Europe, is in the ice-water transition phase at a temperature slightly below the 0°C. Analysis of geophysical and hydrogeological data indicates the possibility of preserving the permafrost in the central part of sedimentary cover of the Suwalki Anorthosite Massif over an area of probably 50 km 2 . Preliminary results of geothermal modelling indicate maximum palaeothickness of permafrost at the end of the Last Glacial Maximum of probably ~600 m. The development of such a thick permafrost results both from a very low average annual temperature in the Weichselian Glaciation and a very low terrestrial heat flow density. It is very probable that similar zones of deep relict permafrost occurrences, undetected so far, may exist in other areas of the Precambrian Platform not only in Poland, but also in the neighbouring countries.

НАУЧНЫЕ ПОДХОДЫ В ОБЕСПЕЧЕНИИ КАЧЕСТВА И БЕЗОПАСНОСТИ ПЛОДОВ И ОВОЩЕЙ В ПРОЦЕССЕ ХРАНЕНИЯ. МИРОВОЙ ОПЫТ. ЧАСТЬ 1

Researchers perform a thorough search and develop new storage methods. Some of them are put into practice: storage in gas modified environments, in the context of active ventilation, increase in and maintenance of moisture and temperature conditions in a warehouse, ozone treatment of the warehouse, etc. The article presents the research results of Russian and foreign scholars in the field of enabling technologies for maintaining quality of fruit and vegetables during the storage. Based on the data given in the public media there is a collection of advanced technologies, in particular, ionizing radiation, thermal influence, nanocomposite films and ultrasonic effect. The researchers of Texas University have proved that the irradiation efficiency for fresh fruit and vegetables requires not only a relevant irradiation source, but also innovative packaging systems, which can ensure radiosensibility to improve product safety without deteriorating their organoleptic characteristics. The optimal modes of broccoli irradiation are: an accelerator 10 MeV, using the configuration with a double beam (upper and lower impact). In this case the product has 132.5 degrees between the beams, and each entrance dose makes up 0.71 kGy (Gy is a measuring unit of absorbed dose. 1 Gray = 100 rad). The researchers have revealed that the best conditions for keeping fruit and vegetables are achieved by creating temperatures that are close to cryoscopic ones. However, to exclude freezing of a product during the storage special temperature reserves until the point of water-ice transition are required. The ultrasonic treatment is quite promising, as it makes it possible to create a special environment in the food system. In case of insignificant change of acidity the water is electrolyzed. This water can be effectively applied for potato processing. Thus, the obtained environmentally friendly antimicrobial agent helps to improve the microbiological safety of potato during the storage.

STRESSES IN CEMENT-CONCRETE PAVEMENT SURFACING CAUSED BY THERMAL SHOCK

It is necessary to mention specially so-called thermal shock among various impacts on highway surface. Ice layer is formed on a concrete surface during the winter period of pavement surfacing operation. Sodium chloride which lowers temperature of water-ice transition temperature and causes ice thawing at negative temperature is usually used to remove ice from the pavement surface. Consequently, temperature in the concrete laying immediately under a thawing ice layer is coming down with a run that leads to significant stresses. Such phenomenon is known as a thermal shock with a meaning of local significant change in temperature. This process is under investigation, it has practical importance for an estimation of strength and longevity of a cement-concrete pavement surfacing and consequently it is considered as rather topical issue. The purpose of investigations is to develop a mathematical model and determination of shock blow permissible gradients for a cementconcrete road covering. Finite difference method has been used in order to determine stressed and deformed condition of the cement-concrete pavement surfacing of highways. A computer program has been compiled and it permits to carry out calculation of a road covering at various laws of temperature distribution in its depth. Regularities in distribution of deformation and stresses in the cement-concrete pavement surfacing of highways at thermal shock have been obtained in the paper. A permissible parameter of temperature distribution in pavement surfacing thickness has been determined in the paper. A strength criterion based on the process of micro-crack formation and development in concrete has been used for making calculations. It has been established that the thermal shock causes significant temperature gradients on the cement-concrete surfacing that lead to rather large normal stresses in the concrete surface layer. The possibility of micro-crack formation in a road covering is determined with the help of such characteristics as material strength, conditions of plate anchoring and a temperature gradient.

Density and Phonon-Stiffness Anomalies of Water and Ice in the Full Temperature Range.

The specific-heat difference between the O:H van der Waals bond and the H-O polar-covalent bond and the Coulomb repulsion between electron pairs on adjacent oxygen atoms determine the angle-length-stiffness relaxation dynamics of the hydrogen bond (O:H-O), which is responsible for the density and phonon-stiffness oscillation of water ice over the full temperature range. Cooling shortens and stiffens the part of relatively lower specific-heat, and meanwhile lengthens and softens the other part of the O:H-O bond via repulsion. Length contraction/elongation of a specific part always stiffens/softens its corresponding phonon. In the liquid and in the solid phase, the O:H bond contracts more than the H-O elongates, hence, an O:H-O cooling contraction and the seemingly "regular" process of cooling densification take place. During freezing, the H-O contracts less than the O:H elongates, leading to an O:H-O elongation and volume expansion. At extremely low temperatures, the O:H-O angle stretching lowers the density slightly as the O:H and the H-O lengths change insignificantly. In ice, the O-O distance is longer than it is in water, resulting in a lower density, so that ice floats.

Water–Ice Transition at 274.1 K in the Channels between Single-Walled Carbon Nanotubes

The effects of confinement in channels between single-walled carbon nanotubes (SWNTs) on the water to ice transition temperature are studied in this work. The channels are provided in the SWNT rope, which are formed between SWNTs when SWNT films are treated with diamond wire drawing dies. Gold wires and aluminum tapes are used as electrodes to connect SWNT rope. When we carried out the measurement, a part of SWNT rope was dipped into water, and the electrical property of the SWNT rope was monitored with decreasing temperature. A sharp jump in voltage is found when the temperature is 274.1 K, which represents the transition temperature of confined water in the channels between SWNTs. These results indicate that the temperature of water–ice transition increases due to its confinement in nanometer size channels compared to that of bulk water. The mechanisms of our observation are discussed.

Continuum Thermodynamics and Phase-Field Models

Phase transitions between two phases are modelled as space regions where a phase-field changes smoothly. The two phases are separated by a thin transition layer, the so-called diffuse interface. All thermodynamic quantities are allowed to vary inside this layer, including the pressure and the mass density. A thermodynamic approach is developed by allowing for the nonlocal character of the continuum. It is based on an extra entropy flux which is proved to be non vanishing inside the transition layer, only. The phase-field is regarded as an internal variable and the kinetic or evolution equation is viewed as a constitutive equation of rate type. Necessary and sufficient restrictions placed by thermodynamics are derived for the constitutive equations and, furthermore, a general form of the evolution equation for the phase-field is obtained within the schemes of both a non-conserved and a conserved phase-field. Based on the thermodynamic restrictions, a phase-field model for the ice-water transition is established which allows for superheating and undercooling. A model ruling the liquid-vapor phase transition is also provided which accounts for both temperature and pressure variations during the evaporation process. The explicit expression of the Gibbs free enthalpy, the Clausius-Clapeyron formula and the customary form of the vapor pressure curve are recovered.

CANNABIS-INDUCED PSYCHOSIS AS A MODEL OF SCHIZOPHRENIA?

Earlier we developed an approximate method of calculating the radius of permafrost thawing by a cylindrical source with a constant temperature. In this study, we show that the effect of thermal properties changing at the ice-water transition on the radius of thawing in many cases can be neglected. Two typical examples are presented.

Detection of water-ice transition using a lead zirconate titanate/brass transducer

We have examined experimentally and theoretically the resonance frequency of a lead zirconate titanate (PZT)/brass unimorph disk transducer with a water (ice) layer on the brass surface. We showed that the flexural resonance frequency decreased with the presence of a water layer and the decrease in resonance frequency increased with an increasing water amount. Upon lowering the temperature, the freezing transition of the deposited water layer was detected when the resonance frequency of the transducer increased abruptly at the freezing temperature. In contrast to water, an ice layer increased the resonance frequency and the increase in the resonance frequency increased with the ice layer thickness. Theoretically, an analytic expression for the flexural resonance frequency of a unimorph transducer in the presence of an ice (water) layer on the brass surface was obtained in terms of the Young’s moduli, densities, and thickness of the PZT, brass, and ice (water) layers. The theoretical predictions were shown to agree with the experimental results.

Behavior of ice-water transition in dimyristoylphosphatidylethanolamine-water system

Differential scanning calorimetric (DSC) studies on the ice-water transition were performed for gel, metastable crystalline, and stable crystalline phases of a fully hydrated dimyristoylphosphatidylethanolamine (DMPE)-water system. We found that the ice-melting behavior differs among these three phases. Endothermic peaks due to the ice-melting were observed at temperatures below 0°C for the all phases. The starting temperature of ice-melting increases in the following order: gel (−35°C) < metastable crystalline (−20°C)< stable crystalline (−10°C) phases. The numbers of water molecules interacting with a DMPE headgroup were estimated to be 6, 7, and 2 for the gel, metastable crystalline and stable crystalline phases, respectively, from the transition enthalpies of the ice-water transitions. In addition, X-ray diffraction analyses revealed that the thickness of interlamellar water region is also different among the three phases and is less than ca. 0.8 nm for the all phases. Based on these results, the interaction of freezable bound water molecules and DMPE headgroups is discussed from the viewpoint of the relation between ice-melting temperatures and interbilayer hydration forces.

Behavior of ice-water transition in dimyristoylphosphatidylethanolamine-water system

Differential scanning calorimetric (DSC) studies on the ice-water transition were performed for gel, metastable crystalline, and stable crystalline phases of a fully hydrated dimyristoylphosphatidylethanolamine (DMPE)-water system. We found that the ice-melting behavior differs among these three phases. Endothermic peaks due to the ice-melting were observed at temperatures below 0°C for the all phases. The starting temperature of ice-melting increases in the following order: gel (−35°C) < metastable crystalline (−20°C)< stable crystalline (−10°C) phases. The numbers of water molecules interacting with a DMPE headgroup were estimated to be 6, 7, and 2 for the gel, metastable crystalline and stable crystalline phases, respectively, from the transition enthalpies of the ice-water transitions. In addition, X-ray diffraction analyses revealed that the thickness of interlamellar water region is also different among the three phases and is less than ca. 0.8 nm for the all phases. Based on these results, the interaction of freezable bound water molecules and DMPE headgroups is discussed from the viewpoint of the relation between ice-melting temperatures and interbilayer hydration forces.