Nuclear Magnetic Resonance Methods Research Articles

Separation of flavonoids with significant biological activity from Acacia mearnsii leaves.

Acacia mearnsii leaves, which are a rich source of flavonoids, were used to separate and purify myricitrin (W3) and myricetin-3-O-glucoside (W1). Further, the antioxidant and hypoglycemic activities of the two purified flavonoids were evaluated. The flavonoids were separated using solvent partition, macroporous adsorbent resin column, and Sephadex column chromatography, and purified using preparative reverse-phase high-performance liquid chromatography (HPLC). The purified flavonoids were characterized using HPLC, mass spectrometry, and nuclear magnetic resonance methods. A high yield (7.3 mg g-1 of crude extract) of W3 was obtained, with a high purity of 98.4%. Furthermore, the purity of W1 was over 95%. W1 and W3 showed strong antioxidant activity and significantly inhibited α-glucosidase. W3 also demonstrated substantial α-amylase inhibitory capacity. This study indicated that A. mearnsii leaves, which are discarded in significant amounts, can be used as a source of myricitrin, thus providing more adequate material for the production of antioxidants and type II diabetes inhibitors. Hence, A. mearnsii leaves have the potential to create great market economic value and environmental benefits.

SYNTHESIS AND ANTIRADICAL ACTIVITY OF CONJUGATES OF URACIL DERIVATIVES WITH AMINO ACIDS

Two synthesis schemes for obtaining new derivatives of 5-hydroxy-1,3,6-trimethyluracil with fragments of protected natural amino acids are proposed. Synthesis includes two ways of obtaining products – chlorohydride, consisting of the protection of amino acids with phthalic acid and further production of chlorohydrides with their subsequent condensation in methylene chloride with uracil derivative, as well as carbodiimide, with tert-butoxycarbonyl protection of amino acids by amino group, also carried out in methylene chloride in the presence of a water-removing agent N,N’-dicyclohexylcarbodiimide. Both methods of placing protective groups in amino acid molecules are described. New compounds were obtained with yields of 65-98%. Also, by the method of N-alkylation with ethylene chlorohydrin, a linker was introduced into the 6-methyluracil molecule with subsequent separation of N1- and N3-derivatives. The reaction was optimized, and the ratio of reagents was revealed, at which the highest yield of the product alkylated at the N3- position is achieved. Successful attempts to attach amino acid fragments to the resulting N3-(2-hydroxyethyl)-6-methyluracil during boiling in ethyl alcohol are described. Due to the high biological activity of all the starting substances, the authors predicted the presence of possible reaction products. The article presents the results of studies of the antiradical (antioxidant) activity of 6-methyluracil derivatives based on the inhibition of the free radical 2,2-diphenylpicrylhydrazine by solutions of specified compounds with different concentrations. It was found that the synthesized conjugates, in particular N3-(2-hydroxyethyl)-6-methyluracil with the amino acid methionine attached via a linker, have increased values of the specified activity in comparison with the initial 6-methyluracil, which makes it possible for their further study. The newly obtained compounds were characterized by the methods of 1H and 13C nuclear magnetic resonance. For citation: Khazimullina Yu.Z., Gimadieva A.R. Synthesis and antiradical activity of conjugates of uracil derivatives with amino acids. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 2. P. 36-44. DOI: 10.6060/ivkkt.20236602.6652.

Protein Cage Relaxivity Measurement for Magnetic Resonance Imaging Contrast Agents.

Contrast agents are employed to enhance the differentiation of diseased cells or lesions from normal tissues in magnetic resonance imaging (MRI). Protein cages have been explored as templates to synthesize superparamagnetic MRI contrast agents for decades. The biological origin imparts natural precision in forming confined nano-sized reaction vessels. With natural capacity to bind divalent metal ions, ferritin protein cages have been used for the synthesis of nanoparticles containing MRI contrast agents inside their core. Furthermore, ferritin is known to bind transferrin receptor 1 (TfR1) which is overexpressed on specific cancer cell types and could be used for targeted cellular imaging. In addition to iron, other metal ions such as manganese and gadolinium have been encapsulated within the core of ferritin cages. To compare the magnetic properties of ferritin loaded with contrast agents, a protocol for calculating the contrast enhancement power of protein nanocage is required. The contrast enhancement power is demonstrated as relaxivity and can be measured using MRI and solution nuclear magnetic resonance (NMR) methods. In this chapter, we present methods for measuring and calculating the relaxivity of ferritin nanocagesloaded with paramagnetic ions in solution (in tube) with NMR and MRI.

Methods for Structure Determination of SH2 Domain-Phosphopeptide Complexes by NMR.

Nuclear magnetic resonance (NMR) spectroscopy is a powerful technique to solve the structure of biomolecular complexes at atomic resolution in solution. Small proteins such as Src-homology 2 (SH2) domains have fast tumbling rates and long-lived NMR signals, making them particularly suited to be studied by standard NMR methods. SH2 domains are modular proteins whose function is the recognition of sequences containing phosphotyrosines. In this chapter, we describe the application of NMR to assess the interaction between SH2 domains and phosphopeptides and determine the structure of the resulting complexes.

NMR spectroscopy to study cyclodextrin-based host-guest assemblies with polynuclear clusters.

Natural cyclodextrin (CD) macrocycles are known to form diverse inclusion complexes with a wide variety of organic molecules, but recent work has revealed that inorganic clusters also form multicomponent supramolecular complexes and edifices. Such molecular assemblies exhibit a high degree of organization in solution governed by various chemical processes including molecular recognition, host-guest attraction, hydrophobic repulsion, or chaotropic effect. Nuclear magnetic resonance (NMR) spectroscopy is one of the most efficient and practical analytical techniques to characterize the nature, the strength and the mechanism of these interactions in solution. This review provides a brief overview on recent examples of the contribution of NMR to the characterization of hybrid systems in solution based on CD with polynuclear clusters, including polyoxometalates (POMs), metallic clusters and hydroborate clusters. The focus will be first on using 1H (and 13C) NMR of the host, i.e., CD, to identify the nature of the interactions and measure their strength. Then, 2D NMR methods will be illustrated by DOSY as a means of highlighting the clustering phenomena, and by NOESY/ROESY to evidence the spatial proximity and contact within the supramolecular assemblies. Finally, other NMR nuclei will be selected to probe the inorganic part as a guest molecule. Attention will be paid to classical host-guest complexes Cluster@CD, but also to hierarchical multi-scale, multi-component assemblies such as Cluster@CD@Cluster.

Exploring multivalent carbohydrate-protein interactions by NMR.

Nuclear Magnetic Resonance (NMR) has been widely employed to assess diverse features of glycan-protein molecular recognition events. Different types of qualitative and quantitative information at different degrees of resolution and complexity can be extracted from the proper application of the available NMR-techniques. In fact, affinity, structural, kinetic, conformational, and dynamic characteristics of the binding process are available. Nevertheless, except in particular cases, the affinity of lectin-sugar interactions is weak, mostly at the low mM range. This feature is overcome in biological processes by using multivalency, thus augmenting the strength of the binding. However, the application of NMR methods to monitor multivalent lectin-glycan interactions is intrinsically challenging. It is well known that when large macromolecular complexes are formed, the NMR signals disappear from the NMR spectrum, due to the existence of fast transverse relaxation, related to the large size and exchange features. Indeed, at the heart of the molecular recognition event, the associated free-bound chemical exchange process for both partners takes place in a particular timescale. Thus, these factors have to be considered and overcome. In this review article, we have distinguished, in a subjective manner, the existence of multivalent presentations in the glycan or in the lectin. From the glycan perspective, we have also considered whether multiple epitopes of a given ligand are presented in the same linear chain of a saccharide (i.e., poly-LacNAc oligosaccharides) or decorating different arms of a multiantennae scaffold, either natural (as in multiantennae N-glycans) or synthetic (of dendrimer or polymer nature). From the lectin perspective, the presence of an individual binding site at every monomer of a multimeric lectin may also have key consequences for the binding event at different levels of complexity.

Phenol, the simplest aromatic monohydroxy alcohol, displays a faint Debye-like process when mixed with a nonassociating liquid.

Solvated in propylene carbonate, viscous phenol is studied using dielectric spectroscopy and shear rheology. In addition, several oxygen-17 and deuteron nuclear magnetic resonance (NMR) techniques are applied to specifically isotope labeled equimolar mixtures. Quantum chemical calculations are used to check the electrical field gradient at phenol's oxygen site. The chosen combination of NMR methods facilitates the selective examination of potentially hydrogen-bond related contributions as well as those dominated by the structural relaxation. Taken together the present results for phenol in equimolar mixtures with the van der Waals liquid propylene carbonate provide evidence for the existence of a very weak Debye-like process that originates from ringlike supramolecular associates.

Molecular mechanisms of amyloid-β peptide fibril and oligomer formation: NMR-based challenges.

To completely treat and ultimately prevent dementia, it is essential to elucidate its pathogenic mechanisms in detail. There are two major hypotheses for the pathogenesis of Alzheimer's dementia: the β-amyloid (Aβ) hypothesis and the tau hypothesis. The modified amyloid hypothesis, which proposes that toxic oligomers rather than amyloid fibrils are the essential cause, has recently emerged. Aβ peptides [Aβ(1-40) and Aβ(1-42)] form highly insoluble aggregates in vivo and in vitro. These Aβ aggregates contain many polymorphisms, whereas Aβ peptides are intrinsically disordered in physiological aqueous solutions without any compact conformers. Over the last three decades, solid-state nuclear magnetic resonance (NMR) has greatly contributed to elucidating the structure of each polymorph, while solution NMR has revealed the dynamic nature of the transient conformations of the monomer. Moreover, several methods to investigate the aggregation process based on the observation of magnetization saturation transfer have also been developed. The complementary use of NMR methods with cryo-electron microscopy, which has rapidly matured, is expected to clarify the relationship between the amyloid and molecular pathology of Alzheimer's dementia in the near future. This review article is an extended version of the Japanese article, Insights into the Mechanisms of Oligomerization/Fibrilization of Amyloid β Peptide from Nuclear Magnetic Resonance, published in SEIBUTSU BUTSURI Vol. 62, p. 39-42 (2022).

Experimental Investigation on the Imbibition Behavior of Nanofluids in the Tight Oil and Gas Reservoir through the Application of Nuclear Magnetic Resonance Method

Tight oil and gas resources are widely distributed and play an important role in the petroleum industry. Due to its nanoscale pore-throat characteristics, the capillary effect is remarkable, and spontaneous imbibition is very beneficial to the development of low-permeability reservoirs. In this study, the imbibition experiments of 2D nano blackcard, nanoemulsion, and water were carried out, respectively. The pore-throat fluid distribution characteristics before and after core imbibition were analyzed with nuclear magnetic resonance technology, and the enhanced oil recovery effects of 2D nano blackcard nanoemulsion, and water were comprehensively evaluated. The results show that the final recovery factors of cores soaked in 2D nano blackcard (0.005 ωt%) and nanoemulsion (0.02 ωt%) or imbibed in water are 32.29%, 26.05%, and 7.19%, respectively. It can be found that 2D nano blackcard is the fluid with the best imbibition effect. In this work, a new type of 2D nano blackcard was proposed and identified as a functional imbibition fluid for enhanced oil recovery in tight reservoirs, providing a practical reference for the effective development of tight, low-permeability oil and gas reservoirs.

Nontargeted metabolomics integrated with 1 H NMR and LC-Q-TOF-MS/MS methods to depict a more comprehensive metabolic profile in response to chrysosplenetin and artemisinin co-treatment against artemisinin-sensitive and -resistant Plasmodium berghei K173.

Our previous work revealed mutual and specific metabolites/pathways in artemisinin-sensitive and -resistant Plasmodium berghei K173-infected mice. In this study, we further investigated whether chrysosplenetin, a candidate chemical to prevent artemisinin resistance, can regulate these metabolites/pathways by integrating nontargeted metabolomics with 1 H NMR and LC-Q-TOF-MS/MS spectrum. The nuclear magnetic resonance method generated specifically altered metabolites in response to co-treatment with chrysosplenetin, including: the products of glycolysis such as glucose, pyruvate, lactate and alanine; taurine, closely associated with liver injury; arginine and proline as essential amino acids for parasites; TMAO, a biomarker for dysbacteriosis and renal function; and tyrosine, which is used to generate levodopa and dopamine and may improve the torpor state of mice. Importantly, we noticed that chrysosplenetin might depress the activated glycolysis induced by sensitive parasites, but oppositely promoted the inhibited glycolysis to generate more lactate, which suppresses the proliferation of resistant parasites. Moreover, chrysosplentin possibly disturbs the heme biosynthetic pathway in mitochondria. The MS method yielded changed coenzyme A, phosphatidylcholine and ceramides, closely related to mitochondria β-oxidation, cell proliferation, differentiation and apoptosis. These two means shared no overlapped metabolites and formed a more broader metabolic map to study the potential mechanisms of chrysosplenetin as a promising artemisinin resistance inhibitor.

Multi-scale Pore Structure Characterization of Lacustrine Fine-Grained Mixed Sedimentary Rocks and Its Controlling Factors: A Case Study of Lucaogou Formation in Jimusar Sag

The microscopic pore structure of fine-grained mixed sedimentary rocks (FMSRs) is of great significance for the occurrence mechanism and sweet spot optimization of mixed shale oil. At present, there is no clear understanding of the microscopic pore system of FMSRs and their coupling relationship with rock composition, which restricts the fine understanding of the reservoir forming mechanism of this type of reservoir. Taking the FMSR samples of the Permian Lucaogou Formation in the Jimusar Sag, the southeastern margin of the Junggar Basin, China, as an example, this paper quantitatively characterizes the full-scale pore structure of lacustrine FMSRs by casting thin sections, scanning electron microscopy, low-temperature nitrogen adsorption (LTNA), high-pressure mercury injection, and nuclear magnetic resonance (NMR); analyzes the coupling relationship between the full-scale pore structure and rock composition; and then summarizes the controlling factors. The results showed that the full-scale pore size distribution (PSD) can be revealed by combining the LTNA and NMR methods. The PSDs of FMSRs are evaluated, mostly corresponding to small pores (30–200 nm) and mesopores (200–1500 nm). The sediment grain size, mineral composition, sedimentary environment, and diagenesis jointly controlled the development of FMSR reservoirs. The development of coarser grain components (such as fine sand and arenaceous dolomite), high content of feldspar, low content of clay and calcite, and appropriate content of dolomite (less than 20%) were conducive to high-quality reservoirs. A near-provenance sedimentary pore throat is better. Siltstones, dolomitic siltstones, and dolarenites were mainly developed in shoreland sandy bar, distal sand bar, and dolomitic mud flat microfacies; type I pore throats with residual intergranular pores and dissolved pores are the most favorable for the Lucaogou Formation.

Enzymatic Conversion of Hydrolysis Lignin—A Potential Biorefinery Approach

Lignin is an abundant and renewable source capable of replacing different raw materials in the chemical industry. It can be obtained from lignocellulosic biomass (LCB) via different pretreatment methods. In the present study, hydrolysis lignin (HL) from the SunburstTM pretreatment technology was utilized to investigate its enzymatic conversion. At first, soluble HL fractions were obtained via alkali solubilization followed by acid precipitation, referred to as acid precipitated lignin (APL). Furthermore, the APL was tested with three different bacterial laccases to identify the optimal conditions for its conversion into small molecular weight fractions. Among the tested laccases, Streptomyces coelicolor A3(2) (ScLac) displayed the highest rate of APL conversion with a high lignin dosage and under extremely alkaline conditions, i.e., 50 g/L in 0.25 M NaOH solution, resulting in higher molecular weight fractions. The increase in the molecular weight and quantitative linkages before and after the enzymatic oxidation of the APL were characterized by size exclusion chromatography (SEC), Fourier-transform infrared spectroscopy (FT-IR), and two-dimensional heteronuclear single quantum correlation nuclear magnetic resonance (2D HSQC NMR) methods.

Experimental Study on Fractal Characteristics of Adsorption Pore Structure of Coal

The adsorption pore structure is the key affecting the technology of enhanced coal bed methane recovery (ECBM). In this paper, nitrogen adsorption measurement (NAM) and low-field nuclear magnetic resonance (NMR) methods are used to test the structural parameters of adsorption pores of four coal samples with different metamorphic degrees. Combining with the fractal theory, the applicability and the physical significance of fractal dimensions obtained from different models are analyzed. Finally, the main factors affecting the complexity of the pore size structure and the influence of fractal characteristics on the adsorption properties of coal are discussed. The results show that with the increase in the degree of metamorphism, the ranking order of the volume and the specific surface area of adsorption pores of four coal samples are long flame coal > anthracite > gas coal > coking coal. The fractal dimension D2 calculated by the Frenkel–Halsey–Hill (FHH) fractal model ranges from 2.5 to 2.9, representing the degree of the pore surface irregularity, and D3 calculated by the FHH fractal model ranges from 2.004 to 2.037, representing the complexity of pore size distribution. There is no clear quantitative relationship between the fractal dimension and the single structure parameters of adsorption pores. The more the pore diameter distribution is concentrated in the range of 2–5 nm, the larger the fractal dimension is, the higher the complexity of adsorption pore structure is; D2, which represents the irregularity of the surface of coal, has a good linear positive correlation with the maximum adsorption capacity of N2.

Investigation of Stress Sensitivity of Shale Nanopores via a Nuclear Magnetic Resonance Method

Nuclear magnetic resonance (NMR) is widely used to characterize the pore structure of rock. The nanoscale pores and fractures are well developed in a shale gas reservoir. The closure of nanopores caused by the increase in effective stress during the gas production process could induce stress sensitivity in shale nanopores, which has a great impact on the single-well productivity in the middle–late development stage. In this paper, shale samples from the Longmaxi Formation were taken to investigate the nanopore stress sensitivity via an NMR method. Samples with different degrees of pore and fracture development were selected and NMR experiments under different effective stress conditions were carried out. The results show that: (1) As the effective stress increases, the pore space in shale is continuously compressed, and the cumulative pore volume of shale decreases; (2) There is a more pronounced decrease in the cumulative pore volume of samples containing larger pores with the increase in effective stress. However, there are obvious differences in the pore volume changes in different pore sizes; (3) The transformation of nanopores of different sizes occurs in the process of effective stress loading. When the effective stress is small, the pores with diameters larger than 50 nm are mainly transformed to those with diameters of 10–50 nm. When the effective stress increases to a certain extent, the pores with diameters of 10–50 nm are mainly transformed to those with diameters of 0–10 nm; (4) There are significant differences in the compressibility of nanopores of different sizes. Larger nanopores generally have a higher compression coefficient and a stronger stress sensitivity. In the process of effective stress loading, the compression coefficient of pores with diameters between 10 and 50 nm changes relatively slowly, which can well-maintain the pore shape and quantity. Based on the variation in porosity ratio with effective stress, a new method of dividing shale nanopores is proposed; those with diameters smaller than 10 nm, those with diameters of 10–50 nm, and those with diameters larger than 50 nm.

Diffusion NMR for Measuring Dynamic Ligand Exchange on Colloidal Nanocrystals.

Ligand exchange is fundamentally related to the surface chemistry of nanoparticles in solution and is also an essential procedure for their synthesis and solution processing. The solution of ligand-bearing nanoparticles can be regarded as a dynamic equilibrium of bound and free ligands depending on the concentration and temperature. The direct experimental calibration of the ligand exchange dynamics relies on the in situ and real-time quantification of bound and free ligands. However, existing analytical strategies are often with limited applicability considering the requirement of special functional groups or the indirect detection of photoluminescence or reaction heat. In this work, we explore diffusion-based methods of solution-state nuclear magnetic resonance (NMR) as a general strategy to probe ligand exchange. Using comprehensive numerical simulations, we show that diffusion NMR with designable time sequences can effectively distinguish bound and free ligands and measure the exchange rate constants from 0.5 to 200 s-1 under typical instrumental settings. These methods are demonstrated experimentally on colloidal CdSe nanocrystal systems with carboxylate or amine ligands whose exchange rates were previously undetectable. The kinetic rate constants, activation energies, and thermodynamic parameters of ligand exchange have been obtained under variable temperature conditions. We expect the diffusion NMR strategies to be generally applicable for calibrating the exchange of organic ligands on various nanoparticle systems.

Electronic Structure and Hyperfine Interactions in Cr$$_x$$NbSe$$_2$$ (x = 0.33, 0.5) by DFT Studies

The first principles calculations of the electronic structure and hyperfine interactions of Cr\(_x\)NbSe\(_2\) (x = 0.33, 0.55) chalcogenides are presented. As a result, the values of the hyperfine fields and the parameters of the quadrupole interaction were determined for different arrangements of chromium ions. Ab initio calculations are compared with data obtained by the nuclear magnetic resonance methods on the \(^{53}\)Cr and \(^{93}\)Nb nuclei. It has been shown that Cr\(^{3+}\) ions have a high degree of hybridization of \(a_{1g}\) and \(e_g\) orbitals of 3d-electrons with 4d and 5s orbitals of niobium. It has been established that two nonequivalent environments of chromium ions coexist in Cr\(_{0.33}\)NbSe\(_2\) compound.

Novel Nuclear Magnetic Resonance Techniques To Assess the Wax Precipitation Evolution in Crude Oil Systems

Wax crystallization in cold environments constitutes one of the main causes for flow assurance problems during oil production. Several techniques, such as differential scanning calorimetry (DSC) or gas chromatography/mass spectroscopy (GC/MS), are currently the established methods for the quantification of wax precipitation. Low-field nuclear magnetic resonance (NMR) techniques have seldom been used for the investigation of wax precipitation, despite early studies showing their ability to identify the rate of precipitation. This paper highlights three NMR methods, adapted for the purpose of wax crystallization quantification in crude oil systems. The proposed methods are based on free induction decay (FID) and Carr–Purcell–Meiboom–Gill (CPMG) sequences. Both allow for the quantification of a signal that is proportional to the non-crystalline wax content, while FID data can also be used for the computation of the crystalline wax component in systems with a sufficiently high wax content. DSC is also used as a reference method for wax content quantification. Model system analysis demonstrates consistency between the three methods in toluene-based wax solutions and also highlights a thorough comparison between macro- and microcrystalline waxes. Similar results are obtained with the four methods for crude oils with a high wax content, and a relevant comparison between different systems can be achieved for oils with wax concentrations as low as 2% at 0 °C. Overall, the determination of the solid content with FID represents an improved, more reliable method, which can be utilized during the creation of more robust flow assurance methods.

Flow NMR system development for real-time in situ multiple detection of direct methanol fuel cell exhausts

Understanding the electrochemical reaction mechanisms of energy conversion and storage systems is essential for improving their performance. Nuclear magnetic resonance (NMR) spectroscopy is an excellent quantitative and qualitative analysis method for investigating electrochemical reactions. We developed in situ real-time 2H flow NMR spectroscopy using a toroid cavity detector to simultaneously acquire the spectra of the anode and cathode exhausts of a direct methanol fuel cell. We used deuterium-enriched methanol (CD3OH) as fuel in order to obtain background-free spectra. Besides HOD, the CD3OH crossed over from the anode was observed in the cathode exhaust. The amount of CO2 gas, which is impossible to detect with ex situ NMR spectroscopy, was proportional to the HOD amount and current generated during the cell operation at a given potential. Therefore, in situ real-time analysis enabled us to identify and quantify the anode and cathode exhaust chemical components, including the gaseous products, such as CO2, of a fuel cell. This explains differences in the fuel cell performance by identifying generated and consumed chemicals and their pathways in the cells at respective conditions. Hence, our results demonstrate that this in situ real-time flow NMR method is applicable to studying the reaction mechanism of various other liquid-flowing chemical reaction systems besides fuel cells. Furthermore, it may open a new door for designing advanced materials.

Refining of the oil from asphaltene-resins and paraffins

THE PURPOSE. To consider the problems of express-control and asphalten-resins and paraffins (ARP) purification of oil from them. Elaborate new methods of oil-well liquid and oil express-contro, especially of ARP. The task is actual, because great amount of ARP lead to ARP – deposits in pipeline, which result to complications in oil-mining, increase of power consumption and wearing of machinery. Elaborate the technology and installation for removing ARP from oil under affect of physical fields. METHODS. When solving this problem, we used the backward/forward method of nuclear (proton) magnetic resonance (PMR) relaxometr, which is noncontact, nondestructive, does not need probe preparense. For ARP removing were used: rotating magnetic, nonuniform alternating electric, centrifugal fields and gravitation separation of emulsion. Was used also physica modeling and MatLab Simulink mathematical modeling.RESULTS. Elaborated the methodics of express-control of ARP and water concentrations, disperse distributions of water solutions of ARP with reagents in emulsions. Were received experimental equations between ARP and water concentrations and times of PMR spin-spin relaxations, which gives the opportunity determine the oil characteristics from NMR-parameters. Theoreticall grounded the technology of the ARP removing from oil, described the forces, affecting on droplets in the rotating magnetic, nonuniform alternating electric, centrifugal fields. Elaborated the structure-functional scheme of installation for purification of oil from ARP, controlled by elaborated relaxometer NMR-NP2. Made the calculation of the rotating magnetic resonance source, its optimization and physical, mathematical modeling of its function in Matlab Simulink program. CONCLUSION. The survey of methodic and instrumental equipment of oilmining deposits showed, that control of studied oil characteristics is carried in laboratories, expensive and long in time, there is no instrumental method of ARP determination and removing. Were received experimental equations for the asphaltene-resins control in the range 0-30% withthe accuracy of »±2 %, for paraffinsin the range 0-30% withaccuracy »± 3 %, droplets distribution in the range 1-20 mm withaccuracy »± 1mm, offered the installation for ARP removing from oil.

Dynamic mode I fracture properties of saturated white sandstone under ambient sub-zero temperatures

Dynamic fracture properties of frozen rocks are essential for better designs of rock engineering infrastructures in cold regions. Thus, a dynamic-cryogenic testing system combined with a high-speed camera is adopted to conduct dynamic tests under ambient room and sub-zero temperatures (20 °C, −10 °C, −20 °C, and −30 °C). A porous white sandstone (WS) is used to fabricate notched semi-circle bend (NSCB) specimens for mode I dynamic fracture tests. The percentage of ice and unfrozen water in rock pores under different temperatures is quantified using the nuclear magnetic resonance (NMR) method. For comparison purpose, dry specimens are also tested under the same ambient temperatures. The results show that the dynamic fracture toughness (DFT) for two sets of specimens all show obvious rate dependency. Except for −30 °C, DFTs of dry specimens are marginally influenced by the sub-zero temperatures. On the contrary at a given loading rate, DFT of frozen saturated specimens first drops to the lowest value at −10 °C before further increasing with the dropping ambient temperature. Compared with dry specimens, saturated specimens show lower DFTs and crack propagation velocities that are quantified with the digital image correlation (DIC) method. The experimental results are explained invoking the rock weakening and enhancing mechanisms of the ice and unfrozen water mixture in rock pores. These results are useful to blasting designs in cold areas.