Search

We present a new Moho map for the north-eastern part of Eurasia, which remains almost non-studied by seismic methods. The new map is based on the analysis of various data sets. The key fields are the residual gravity, topography and vertical gravity gradients of GOCE (Gravity field and steady-state Ocean Circulation Explorer). Using three fields enables improvement of the final results and better separation of the Moho effect. In the first step, the effects of sediments, crystalline crust and upper mantle were removed from the observed fields based on existing crustal and tomography models. The residual fields are then inverted in the next step to find perturbations in the initial Moho map. In the inversion, it is assumed that some density anomalies are still located in the crust and upper mantle. The new Moho map demonstrates several principal features, which were not resolved before. They well correspond to tectonic fragmentation of the study area. In particularly, the crustal root is now located under the Verkhoyansk Range and extends to the depth of 47 km, also the new model demonstrates the Moho deepening in the continental part of the Laptev rift system. Next, the zone of shallow Moho in the East Siberian Sea shore is now clearly traced and has a more isometric shape compared to the initial model. New patterns have been also found in the offshore part of the Chukotka microcontinent and for the Anadyr-Koryak folded system. The new Moho map is a significant improvement of the previous maps showing crustal thickness in north-eastern Eurasia.

We use solid-state 27Al NMR spectroscopy to test four aluminum-based metal–organic framework (MOF) materials—ICR-2, ICR-4, ICR-6, and ICR-7—against their structural models obtained from electron an...

The chapter includes the summary of unified theory of space–time transformations of fundamental laws of nature in the form of three “great theorems” by Galileo, Lorentz and Poincare. This theory, in light of the initially existing inherent contradictions between three “great geometries” by Euclid, Lobachevsky and Riemann, reflects the dual features of three-dimensional, perspective and projective perception of the world around us through human eyes. Three “great theorems” related to the velocity of light propagation, gravitational radii and Planck’s quantities, reveal the essence of unified theory of space–time transformations. Its significance is considered for describing the total energy of oscillatory and wave processes as well as for formulating the fundamental laws of its development in the Universe. In light of unified theory of space–time transformations, these three “great theorems” have the dual form of space–time laws. The last ones unite Newtonian physics and thermodynamics with electromagnetic, gravitational, weak and strong fundamental interactions in regard to special nodal and bifurcation, perspective and projective reference points, which serve as the origin of coordinates of unified metric system.

In the chapter, the prerequisites and basic concepts of unified theory of space–time transformations of fundamental laws of nature in the form of three “great theorems” by Galileo, Lorentz and Poincare are considered in detail in the context of three “great geometries” by Euclid, Lobachevsky and Riemann using simple and obvious cases of description of free oscillations of string and the Earth. The author provides formulations and solutions of wave equation for free oscillations of string and radial, spheroidal, torsional free oscillations of the Earth as well. Considering these formulations and solutions from the point of view of new visible event horizons associated with the velocity of light propagation, gravitational radii and Planck’s quantities, the author comes up with the formulation of unified theory of space–time transformations of fundamental laws of nature. From the point of view of exact sciences—mathematics, geometry and physics, the unified theory of space–time transformations of fundamental laws of nature in the form of three theorems by Galileo, Lorentz and Poincare is supposed to be related to further development of infinitely large and infinitesimal in integral and differential calculus in the transition to new visible event horizons, determined by velocity of waves and light propagation, gravitational radii and Planck’s quantities. The chapter also includes the consideration of applied aspects of unified theory of space–time transforms of fundamental laws of nature, in particular, the relation of the Earth’s free oscillations to standing internal gravitational waves that determine the fractal hierarchy of dissipative structures of the Earth, which is associated with many aspects of its geological structure and evolution.

Principal component analysis (PCA) has proved to be a powerful technique for processing NMR data. It is particularly useful in signal quantitation where it often provides better results compared to a direct integration of individual signals. In the present work, we recapitulate the principles and theoretical framework underlying PCA-based quantitation with a special focus on T

In this paper the following information interpretation of uncertainty relation is proposed: if one bit of information was extracted from the system as a result of the measurement process, then the measurement itself adds an additional uncertainty (chaos) into the system equaled to one bit. This formulation is developed by calculating of the Shannon information entropy for the classical N-slit interference experiment. This approach allows looking differently at several quantum phenomena. Particularly, the information interpretation is used for explanation of entangled photons diffraction picture compression.

A facile and efficient method for the improved miscibility of natural polymer/synthetic polymer blends is reported here based on the electric-field-driven phase inversion. We have employed bioderived chitosan (CS) and Polyamide-6 (PA6) as an example since their blends are known to always result in a large scale phase separation (i.e. CS settles to the bottom of the blends as sediment) during phase inversion procedure. The condensed structure of the polymer blends has been well characterized, notably by the polarized attenuated total reflectance infrared spectroscopy and proton longitudinal relaxation time (T1) distribution. The application of an electric field can orient the polar groups which will hinder the crystallization of blends and also increase the interphase interaction between PA6 and CS. The miscibility of the PA6/CS blends has been characterized by scanning electron microscopy and confocal Raman spectroscopy. It is shown that this controllable hydrogen bonding environment, induced by the presence of electric field, indeed greatly hinder the sedimentation of CS without destroying its chemical structure. The improved miscibility of PA6/CS blends can thus significantly increase the toughness and generate a somewhat larger tensile strength.

Principal component analysis (PCA) has proved to be a powerful technique for processing NMR data. It is particularly useful in signal quantitation where it often provides better results compared to a direct integration of individual signals. In the present work, we recapitulate the principles and theoretical framework underlying PCA-based quantitation with a special focus on T1 relaxometry. We show that under commonly encountered conditions, this approach can provide up to ~4-fold improvement in scatter of points in magnetization build-up curves compared to direct integration. Best practices to optimize the PCA performance in measuring the total magnetization are discussed, including minimization of the number of signal-related principal components and a proper selection of FT parameters and data quantitation intervals. For signals consisting of distinct relaxation components, formulas are provided for resolving the components relaxation and illustrated on a real-data example. In addition to the problem of quantitation, the use of PCA in denoising of partially relaxed spectra is discussed in connection with such applications as line shape analysis and monitoring relaxation of individual spectral components.

The principal undertaking of the methods described in this work is to reveal multi-ordinal structures of gravitational instability—or dissipative structures of the Earth—and identify their typomorphic elements. The range of methodological approaches aimed at solving this issue is rather wide and includes: the analysis of seismic tomography data; maps of global geoid anomalies and gravitational potential; graphical and analytical methods for the decomposition of relief, figures representing the Earth’s gravitational field; the deciphering of space and aerial images; morphometric, structural-geomorphological and structural-geological investigations.

The manifestation of the wave properties of matter in the processes of spontaneous structuring of density-unstable masses, originally described as a natural phenomenon characteristic of both the nonequilibrium density-unstable laboratory physical models, and the geological planetary layers and upper horizons of the Earth’s crust, is the basis for new approaches to geological mapping and to the interpretation of geological and geological-geophysical data at all stages of their processing.

The invariance of the revealed regularity in the spatial distribution of different-type hierarchies of the Earth’s gravitational instability structures throughout its geological history, along with the data discussed above on the distribution of mantle plumes and the sialic protocrust with respect to global structures such as G-hexagons in the eastern hemisphere and the L-hexagons in the western, confirms the emergence of these global structures, which determined the fundamental asymmetry of the Earth and divided it into the Indo-Atlantic and Pacific tectonic segments during the early Archean, simultaneously with the isolation of the liquid core, i.e. more than 3500 Ma. At the same time, paleogeodynamic reconstructions show that generational structures emerge during each subsequent stage of the Earth’s evolution, along with disordered instabilities. Moreover, these increasingly massive generational structures are presented predominantly by G-hexagon type in the eastern hemisphere and the L-hexagon type in the western. With the consideration of the relationship between the size and the stratification depth of the structures of gravitational instability, this means that with the course of geological time, the increasingly deep layers of the Earth’s crust and mantle became gravitationally unstable with respect to the underlying shells. From a physical point of view, the increase in the thickness of gravitationally unstable layers over time can easily be explained by the nonequilibrium cooling of the Earth through its surface, i.e., by external sinks of heat. With the increase in the size of the Earth’s gravitational instability structures, the associated tectonic regimes also change, ranging from fine-cellular intraplate (greenstone and granulite, protoaulacogenic and protogeosynclinal) to marginal-plate and global riftogenic regimes. In the terms of geodynamics, the horizontal component in the movement of the Earth’s crust becomes especially critical when the magnitude of its gravitational instability increases. The scale of its destruction increases, and a gradation from small-plate and intraplate tectonics to the tectonics of lithospheric plates can be observed.

Among the many structural features appearing throughout the Universe, including the Earth and its surrounding layers, the attention of contemporary scientists is drawn to the spontaneous structuring of these natural systems and the geometric commonality of the emerging structural forms, i.e., in terms of their cellular (square, hexagonal, polygonal) geometry. The structural similarity of these forms is revealed to be independent of the nature and scale of their manifestation, a factor having already been emphasised by many researchers from a philosophical perspective (V. V. Piotrovsky, M. A. Sadovsky, Yu. M. Pushcharovsky, V. E. Khain, L. I. Krasny, etc.). This has led the scientific community towards the view that the external manifestations of the spontaneous structuring and redistribution of masses in nonequilibrium density distribution in natural systems may be explained in terms of a transphenomenal physical mechanism. This perception is strengthened still further by turning to the applied natural scientific fields of fluid dynamics and thermodynamics, oceanology, meteorology and geophysics, where the same geometric commonality of spontaneous structuring can be seen as underlying otherwise apparently scattered examples.

The natural science of geology is in the first place a descriptive science; nevertheless, in this field a large body of accumulated empirical material is unified at the level of the fundamental laws of nature in the language of modern physics and mathematics. In this connection, we can state that with the development of various physical and mathematical methods for describing the processes of spontaneous structuring of density-unstable media, their wave nature becomes more and more evident regardless of the causes (whether thermodynamic or dynamic) of this instability.

From the standpoint of the material manifestation of wave properties in the processes of spontaneous structuring of unstable masses, the essence of the new general geological paradigm follows from the discovery of the colossal global structures of the Earth’s gravitational instability of G-hexagon type, exhibiting immersion in the centre and emersion in the marginal parts of the deep mantle substrate in the eastern hemisphere, and L-hexagon type, with emersion in the centre and immersion in the marginal parts of the deep mantle substrate in the western hemisphere, the basis of which development is explained in terms of wave processes.

The structure of chain entanglements in the solid state is important for revealing the relationship of structure and properties of polyolefin. In this work, low-field solid-state 1H NMR is used to study the chain dynamics of ultra-high molecular weight polyethylene (UHMWPE) in the solid state. It has been found that the relaxation distribution, analyzed by a multi-exponential inversion program, is an effective method to characterize the heterogeneous chain mobility. It is evidenced from the results that the UHMWPE in a less entangled state presents an obviously heterogeneous distribution of chain mobility in the non-crystalline phase, corresponding to its heterogeneous distribution of entangled points. In comparison, the commercial UHMWPE with a large number of entanglements shows a much more uniform mobility of the non-crystalline components. This heterogeneous distribution of chain mobility becomes even more critical after annealing the samples below the melting point, especially for the less entangled UHMWPE.

Purpose The multi‐exponential character of T1 relaxation in bovine articular cartilage was investigated at low magnetic fields below 0.5 T. The ultimate aim was to identify a parameter based on the T1 relaxation time distribution as a biomarker to biochemical features of osteoarthritis. Methods Osteoarthritis conditions were simulated by enzymatic digestion of cartilage with trypsin. Fast‐field cycling NMR relaxometry was carried out in the magnetic field range B0 = 70 μT to 600 mT. The data were analyzed in terms of T1 distributions on a log‐time scale using inverse Laplace transform, whereas integral properties such as mean T1s and distribution widths were obtained without data inversion from logarithmic moment analysis and a stretched‐exponential fit to the data. Attempts were also made to differentiate between water dynamic components through multi‐Lorentzian decomposition of average relaxation‐rate dispersions. Results T1 distribution in bovine articular cartilage was found to be bimodal, with the dominating, long component shifting toward larger values following trypsin digestion. The effect is more prominent toward lower magnetic field strength. This shift leads to an overall increase of the distribution width and an equivalently more pronounced deviation from exponential behavior. Conclusion The logarithmic width of T1 distribution functions at fields of 0.5 T and below, and the stretched‐exponential decay fit exponent β, show a significant trend after trypsin digestion of cartilage. These 2 parameters are suggested as possible biomarkers for osteoarthritis in humans and can be acquired entirely in vivo, with increasing significance for lower magnetic field strengths.

The dependence of the proton NMR relaxation times on field strength and on location within the tissue has been determined for a number of bovine and human articular cartilage samples. While the strong variation of T2 across the triple-layered cartilage structure as well as its orientation dependence are well known from clinical and laboratory high-field studies, T1 shows similar behavior only in low magnetic fields. At 0.27 T, the ratio of longest to shortest T1 has been found to cover a ratio of about 3-5 in healthy tissue. At the same time, the average T1 was found to be strongly field dependent in the range down to 0.25 mT, but no spatially resolved data are available under these conditions. By correlating the spatially resolved T1 distribution obtained at field strengths of 0.27 T with mathematical decompositions of the signal recovery function into multiexponential components, an attempt is made to quantify the width of P(T1) for variable field strengths, and to identify the field value where this distribution is widest, being optimally situated as a biomarker for laboratory studies or preclinical low-field investigations where spatial resolution is absent or insufficient to resolve the cartilage layer structure.

This work addresses the problem of a compact and easily comparable representation of multi-exponential relaxation data. It is often convenient to describe such data in a few parameters, all being of physical significance and easy to interpret, and in such a way that enables a model-free comparison between different groups of samples. Logarithmic moments (LMs) of the relaxation time constitute a set of parameters which are related to the characteristic relaxation time on the log-scale, the width and the asymmetry of an underlying distribution of exponentials. On the other hand, the calculation of LMs does not require knowing the actual distribution function and is reduced to a numerical integration of original data. The performance of this method has been tested on both synthetic and experimental NMR relaxation data which differ in a signal-to-noise ratio, the sampling range and the sampling rate. The calculation of two lower-order LMs, the log-mean time and the log-variance, has proved robust against deficiencies of the experiment such as scattered data point and incomplete sampling. One may consider using them as such to monitor formation of a heterogeneous structure, e.g., in phase separation, vitrification, polymerization, hydration, aging, contrast agent propagation processes. It may also assist in interpreting frequency and temperature dependences of relaxation, revealing a crossover from slow to fast exchange between populations. The third LM was found to be a less reliable quantity due to its susceptibility to the noise and must be used with caution.

The development of new quantitative magnetic resonance imaging (MRI) technologies open new opportunities for measurements of mass transport in porous media. The current work examines a simple miscible displacement process of H2O and D2O in porous media samples. Laboratory measurements of dispersion in porous media traditionally monitor the effluent intensity of an injected tracer. We employ MRI to obtain quantitative water saturation profiles, and to measure dispersion in rock core plugs. The saturation profiles are modeled with PHREEQC, a fluid transport modeling program. We demonstrate how independent magnetic resonance measurements can be employed to estimate three important input parameters for PHREEQC, mobile porosity, immobile porosity, and dispersivity. Bulk Carr Purcell Meiboom Gill (CPMG) T2 distribution measurements were undertaken to estimate mobile and immobile porosity. Bulk alternating-pulsed-gradient-stimulated-echo (APGSTE) measurements were undertaken to measure dispersivity. The imaging method employed, T2 mapping Spin Echo Single Point Imaging (SE-SPI), also provides information about the pore size distributions in the rock cores, and how the fluid occupancy of the pores changes during the displacement process.

1H relaxometry measurements of petroleum core plugs are commonly performed on low field magnets ( 3 Tesla) are typically employed in small animal MRI studies to improve SNR and image resolution. For many rock core plug samples, susceptibility mismatch effects can be severe at these higher fields leading to decreased T2 and T2*. In this work we seek an answer to the general question of what is the best field for MRI of rock core plugs, anticipating that it will be both sample and measurement method dependent. Free Induction Decay (FID) relaxation time measurements were undertaken to investigate the conditions under which the SNR in Centric Scan SPRITE (Single Point Ramped Imaging with T1 Enhancement) MRI measurements is maximized. The image SNR benefits from greater signal at higher fields, but is negatively impacted by the correspondingly shorter signal lifetimes. Depending on the noise regime of the sample, the maximum SNR may be predicted for Centric Scan SPRITE MRI with T2* being B0 field dependent. In this work we describe a series of simple experimental considerations to determine the optimal B0 field for SPRITE MRI. Selection of the best field is aided by a new generation of superconducting magnets which allows the experimentalist to readily vary the field strength. Such magnets allow one to experimentally control sample magnetization for high sensitivity MRI measurements of core plug samples, while controlling the effect of susceptibility mismatch on the signal lifetimes.

The Open data principle is becoming an increasingly important part of the data revolution, which is recognized worldwide as a key engine for achieving the post-2015 United Nations (UN) Sustainable Development Goals. Open data, publicly available online information that can be used for any purpose at little or no cost, represent one of the most underutilized key assets of modern government. Open data initiatives are often directed at converting open data into formats that can be reused for private sector development, jobs creation, economic growth, and more effective governance and citizen engagement. A 2013 study estimated that using open data in seven sectors of economic activity could create 3 trillion US dollars to 5 trillion US dollars annually in economic value worldwide. The direct, annual economic value of public governmental data has been estimated at up to 40 billion euros for the European Union and 2 billion pounds for the United Kingdom. Numerous examples illustrate how the use of open data can give significant support to achieving the post-2015 UN Sustainable Development Goals.

Two 1-D phase-encode sequences for T 2 mapping, namely CPMG-prepared SPRITE and spin-echo SPI, are presented and compared in terms of image quality, accuracy of T 2 measurements and the measurement time. The sequences implement two different approaches to acquiring T 2 -weighted images: in the CPMG-prepared SPRITE, the T 2 -weighting of magnetization precedes the spatial encoding, while in the spin-echo SPI, the T 2 -weighting follows the spatial encoding. The sequences are intended primarily for T 2 mapping of fluids in porous solids, where using frequency encode techniques may be problematic either due to local gradient distortions or too short T 2 . Their possible applications include monitoring fluid-flow processes in rocks, cement paste hydration, curing of rubber, filtering paramagnetic impurities and other processes accomplished by changing site-specific T 2 .

The freezing and melting temperature hysteresis of water in Vycor porous glass and controlled pore glass (CPG) with the nominal pore diameters 7.0 and 7.5 nm, respectively, has been explored by NMR cryoporometry and NMR relaxometry techniques. The freezing branch of the hysteresis in Vycor was found to be much steeper than the melting one, presumably due to the pore blocking on freezing. This is not observed in CPG, which exhibits parallel freezing and melting branches. Sub-loops recorded starting from partially frozen states are self-similar with respect to the amount of unfrozen water, in both CPG and Vycor. On the other hand, sub-loops starting from partially molten states are self-similar only in CPG, while in Vycor, their shape does depend on the amount of unfrozen water. T 2 relaxation measurements undertaken along the freezing branch reveal in both glasses a slow (on an NMR timescale) exchange of water molecules between frozen and unfrozen pore domains, indicating a good segregation of those domains on freezing. On melting, however, the regime of slow exchange persists only for CPG, while in Vycor, a quasi-exponential T 2 relaxation is observed, characteristic of fast exchange. This suggests that frozen and molten regions in Vycor are well dispersed on melting, while in CPG they present extended domains. We explain such a difference assuming a worse interconnection of a Vycor’s pore space as compared to CPG, taking into account its essentially lower porosity (0.28 versus 0.51 in CPG).

Freezing and melting behaviour of water, benzene, cyclooctane and cyclohexane confined in different-sized controlled pore glasses (CPG's) has been studied by NMR cryoporometry technique. It was fou ...

The depression of the melting temperature of Zn(NO3)2.6H2O was used to obtain the pore size distributions in controlled pore glasses. Measured by 1H NMR, the average value of the temperature depression DeltaT and the known average pore size yield K=DeltaT.d approximately 116 K.nm as the material-dependent factor for Zn(NO3)2.6H2O in the Gibbs-Thompson equation. The melting temperature is close to room temperature. Hence, this salt hydrate and some related other ones are better materials than water (K approximately 50 K.nm) for cryoporometric studies of systems with hydrophilic pores. The data also provide 46 mN/m for the solid-liquid surface tension of this salt hydrate.

NMR cryoporometry is a unique method permitting the investigation of pores in the microporous and mesoporous regimes for samples in aqueous environments. Here, we apply the technique to porous biodegradable polymer microparticles designed as devices for drug delivery in depot formulations. The results indicate that structural features too small to be captured in surface and fracture images obtained by SEM are able to be accessed using the technique, and that the evolution of pore structure can be studied for several days as the particles swell and degrade in the aqueous environment.

We use 7 Li NMR to study the ionic jump motion in ternary 0.5Li 2 S+0.5[(1– x )GeS 2 + x GeO 2 ] glassy lithium ion conductors. Exploring the “mixed glass former effect” in this system led to the assumption of a homogeneous and random variation of diffusion barriers in this system. We exploit that combining traditional line-shape analysis with novel field-cycling relaxometry, it is possible to measure the spectral density of the ionic jump motion in broad frequency and temperature ranges and, thus, to determine the distribution of activation energies. Two models are employed to parameterize the 7 Li NMR data, namely, the multi-exponential autocorrelation function model and the power-law waiting times model. Careful evaluation of both of these models indicates a broadly inhomogeneous energy landscape for both the single ( x =0.0) and the mixed ( x =0.1) network former glasses. The multi-exponential autocorrelation function model can be well described by a Gaussian distribution of activation barriers. Applicability of the methods used and their sensitivity to microscopic details of ionic motion are discussed.

A CPMG pulse sequence incorporated with a DANTE-Z slice selection scheme for measuring spatially-resolved T 2 distributions has been presented. The DANTE-Z pulse train with sinc-modulated pulses selects a single, quasi-rectangular slice of less than 0.8 cm wide at an arbitrary position over a 6-cm long sample. The measured T 2 distributions are of almost the same quality as regular (bulk) CPMG measurements, with the lower T 2 limit being as good as c . a . 0.5 ms. The sequence can be found useful as a supplement or alternative to MRI-based techniques for T 2 mapping in short relaxation time samples (water-saturated rocks, building materials, wood, food products, rubbers, etc.), particularly when T 2 is required to be measured at only few positions along the sample and the resolution of ∼1 cm is acceptable.

Two pure phase encode MRI sequences, CPMG-prepared SPRITE and spin-echo SPI with compressed sensing, for two-dimensional (2-D) T2 distribution mapping have been presented. The sequences are 2-D extensions of their 1-D predecessors previously described and are intended for studying processes in porous solids and other samples with short relaxation times whenever 2-D T2 maps are preferable to simple 1-D profiling. The sequences were tested on model samples and natural water-saturated rocks, in a low field MRI instrument. 2-D spin-echo SPI and CPMG-SPRITE demonstrate a similar performance, enabling measurement of T2 down to 1-2 ms. Both experiments are time consuming (up to 2-2.5 h sample dependent). As such, they can be recommended mostly for measurement during steady state conditions or when studying relatively slow dynamic processes (e.g. enhanced oil recovery, cement paste hydration, curing rubber, infiltration of paramagnetic ions).

Two 1-D phase-encode sequences for T₂ mapping, namely CPMG-prepared SPRITE and spin-echo SPI, are presented and compared in terms of image quality, accuracy of T₂ measurements and the measurement time. The sequences implement two different approaches to acquiring T₂-weighted images: in the CPMG-prepared SPRITE, the T₂-weighting of magnetization precedes the spatial encoding, while in the spin-echo SPI, the T₂-weighting follows the spatial encoding. The sequences are intended primarily for T₂ mapping of fluids in porous solids, where using frequency encode techniques may be problematic either due to local gradient distortions or too short T₂. Their possible applications include monitoring fluid-flow processes in rocks, cement paste hydration, curing of rubber, filtering paramagnetic impurities and other processes accomplished by changing site-specific T₂.

Fluid density imaging is highly desirable in a wide variety of porous media measurements. The SPRITE class of MRI methods has proven to be robust and general in their ability to generate density images in porous media, however the short encoding times required, with correspondingly high magnetic field gradient strengths and filter widths, and low flip angle RF pulses, yield sub-optimal S/N images, especially at low static field strength. This paper explores two implementations of pure phase encode spin echo 1D imaging, with application to a proposed new petroleum reservoir core analysis measurement. In the first implementation of the pulse sequence, we modify the spin echo single point imaging (SE-SPI) technique to acquire the k-space origin data point, with a near zero evolution time, from the free induction decay (FID) following a 90 degrees excitation pulse. Subsequent k-space data points are acquired by separately phase encoding individual echoes in a multi-echo acquisition. T(2) attenuation of the echo train yields an image convolution which causes blurring. The T(2) blur effect is moderate for porous media with T(2) lifetime distributions longer than 5 ms. As a robust, high S/N, and fast 1D imaging method, this method will be highly complementary to SPRITE techniques for the quantitative analysis of fluid content in porous media. In the second implementation of the SE-SPI pulse sequence, modification of the basic measurement permits fast determination of spatially resolved T(2) distributions in porous media through separately phase encoding each echo in a multi-echo CPMG pulse train. An individual T(2) weighted image may be acquired from each echo. The echo time (TE) of each T(2) weighted image may be reduced to 500 micros or less. These profiles can be fit to extract a T(2) distribution from each pixel employing a variety of standard inverse Laplace transform methods. Fluid content 1D images are produced as an essential by product of determining the spatially resolved T(2) distribution. These 1D images do not suffer from a T(2) related blurring. The above SE-SPI measurements are combined to generate 1D images of the local saturation and T(2) distribution as a function of saturation, upon centrifugation of petroleum reservoir core samples. The logarithm mean T(2) is observed to shift linearly with water saturation. This new reservoir core analysis measurement may provide a valuable calibration of the Coates equation for irreducible water saturation, which has been widely implemented in NMR well logging measurements.

We have measured the thickness of the pre-molten surface layer that appears at the interface of octamethylcyclotetrasiloxane (OMCTS) to the matrix in controlled pore glasses with pore diameters ranging 7.5-73 nm. Except for the glass with the largest pores, the layer thickness data for different pore diameters fall on a single master curve when plotted versus Tm - T, where Tm is the size-dependent volume melting point of the pore-confined OMCTS. Hence, at a single temperature, the surface layer thickness depends strongly on the curvature of the pore wall and therefore that of the solid-liquid interface. For temperatures where it exceeds two monolayers, the layer thickness depends logarithmically on Tm - T; for the glass with the largest pores, this turns into a power law with the exponent -1/2. The results are interpreted in terms of a continuous model of the solid-liquid interface with an arbitrary curvature. Because OMCTS is a weakly polar molecule with close to spherical shape, our data also lend themselves to Lennard-Jones type simulations.

Octamethylcyclotetrasiloxane is presented and investigated as probe liquid for NMR cryoporometry or DSC-based thermoporometry. This compound which may imbibe into both hydrophilic and hydrophobic pores is shown to exhibit a melting point depression that is larger than that for other cryoporometric probe materials such as cyclohexane. The transverse relaxation time differs by more than three orders of magnitude between the solid and liquid states, separated by a sharp phase transition. Hence, as demonstrated in controlled pore glasses, octamethylcyclotetrasiloxane can provide pore size distributions for materials with pore sizes up to the micrometer range.

We recapitulate and generalize the concept of the freezing-melting hysteresis that attributes this phenomenon to a free-energy barrier between metastable and stable states of pore-filling material. In a phenomenological description, we show that under commonly encountered conditions, this renders the freezing-point depression DeltaTf defined by the surface-to-volume ratio S/V, whereas the melting-point depression DeltaTm, by the mean curvature kappa of the pore surface, with DeltaTm/DeltaTf =2kappa(V/S). Employing 1H NMR cryoporometry, we experimentally demonstrate the linear correlation between DeltaTm and DeltaTf for several liquids with different DeltaTf,m imbibed in controlled pore glasses. The results compare favorably to the morphological properties of the glasses determined by other techniques. Our findings suggest a simple method for analyzing the pore morphology from the observed phase transition temperatures.

The freezing-melting hysteresis of water in mesoporous silicas MCM-48, MCM-41 and SBA-16 has been studied by NMR cryoporometry. The hysteresis in MCM-48 was found to exhibit nearly parallel branches, matching type H1 hysteresis that had been observed earlier in controlled pore glass. The same type of hysteresis is observed in two of three different-sized MCM-41 under study (a pore diameter of 3.6 and 3 nm), superimposed with a secondary, extremely broad, type H3 hysteresis. No hysteresis was found in the smallest MCM-41 with a pore diameter < 3 nm. Finally, water in SBA-16 exhibits type H2 hysteresis with the freezing branch being essentially steeper than the melting one, which is attributed to a pore blockage upon freezing, similar to what we observed earlier in Vycor porous glass. The data were analyzed using the model of curvature-dependent metastability of a solid phase upon melting; the validity of this model has been discussed.