Nuclear Magnetic Resonance Methods Research Articles

Development of a Nuclear Magnetic Resonance Method and a Near Infrared Calibration Model for the Rapid Determination of Lipid Content in the Field Pea (Pisum sativum).

Pisum sativum is a leguminous crop suitable for cultivation worldwide. It is used as a forage or dried seed supplement in animal feed and, more recently, as a potential non-traditional oilseed. This study aimed to develop a low-cost, rapid, and non-destructive method for analyzing pea lipids with no chemical modifications that would prove superior to existing destructive solvent extraction methods. Different pea accession seed samples, prepared as either small portions (0.5 mm2) of endosperm or ground pea seed powder for comparison, were subjected to HR-MAS NMR analyses and whole seed samples underwent NIR analyses. The total lipid content ranged between 0.57–3.45% and 1.3–2.6% with NMR and NIR, respectively. Compared to traditional extraction with butanol, hexane-isopropanol, and petroleum ether, correlation coefficients were 0.77 (R2 = 0.60), 0.56 (R2 = 0.47), and 0.78 (R2 = 0.62), respectively. Correlation coefficients for NMR compared to traditional extraction increased to 0.97 (R2 = 0.99) with appropriate correction factors. PLS regression analyses confirmed the application of this technology for rapid lipid content determination, with trends fitting models often close to an R2 of 0.95. A better robust NIR quantification model can be developed by increasing the number of samples with more diversity.

Investigation of pore-throat structure and fractal characteristics of tight sandstones using HPMI, CRMI, and NMR methods: A case study of the lower Shihezi Formation in the Sulige area, Ordos Basin

The evaluation of pore-throat structure is essential for the exploration and exploitation of tight oil and gas reservoirs. In this study, various experiments such as casting thin section (CTS), scanning electron microscope (SEM), mercury intrusion porosimetry (MIP), and nuclear magnetic resonance (NMR) are used to investigate the pore-throat structure and fractal characteristics of the tight sandstone from the Permian Shihezi Formation in the Sulige area, Ordos Basin. The type and size of tight sandstone pores and throats are qualitatively analyzed by using CTS and SEM. However, the structural parameters such as the size and distribution of tight sandstone pores and throats are quantitatively calculated by HPMI, CRMI, and NMR. According to the advantages and disadvantages of each method, the HPMI and NMR are combined to characterize the full-size pore-throat distribution (PSD) of tight sandstone. Based on the fractal theory, the fractal dimensions (D) of pore-throat of tight sandstone are evaluated by HPMI, CRMI, and NMR. The result shows the pores in the tight sandstone are mainly residual intergranular pores, dissolution pores, and inter-crystalline pores. There are few micro-cracks developed, and the throats are mainly tubular and curved sheets. The full-size PSD curve of tight sandstone presents the characteristics of the bimodal and unimodal distribution. It has a good agreement with petrophysical properties and movable fluid saturation. Different experimental methods can get different D. HPMI and NMR have different detection ranges and diverse principles for pore-throat evaluation, making sandstone's diverse fractal characteristics. The CRMI is more representative for studying the fractal characteristics of the throat. Moreover, there are two different types of throats: large throat and small throat. These throats have a double fractal feature. The relationship between D and the physical properties analyzes the parameters of the pore-throat structure, suggesting larger the D, the worse the physical properties of the reservoir. The development of the throat (especially the larger throat) controls the storage and fluid flow-ability of tight sandstone reservoirs. Mercury saturation, movable fluid saturation, and D are negatively correlated, indicating that the complicated pore-throat structure will reduce permeability and destroy the free fluid storage space.

Interfacial Structure of Polytrimethylene Terephthalate/Polyethylene Terephthalate Bicomponent Filament

The interfacial structure and binding forces of polytrimethylene terephthalate/polyethylene terephthalate filament were investigated through the methods of Carbon-13 nuclear magnetic resonance (13C-NMR), differential scanning calorimeter (DSC), scanning electron microscopy (SEM) and optical microscopy. When two molten polymers met during the spinning process, an interface layer between the PTT and PET components formed and played an important role in binding the two components together. When the blending time was sufficient, an ester-interchange reaction took place with the generation of the copolymer. The PET recrystallisation was observed in the DSC curve under the influence of entangled PTT molecular chains. The morphology of the cross-section and side view proved that the linear boundary line was short and weaker in binding without a chemical bond and molecular diffusion. Side-by-side bi-component fiber and split-type fiber was able to be controllably spun by adjusting the spinning parameters.

Development of a human insulin certified reference material with SI-traceable purity.

A human insulin (hINS) certified reference material (CRM) was developed by the National Institute of Metrology (NIM). Three milligrams of purified solid hINS was packed into a brown sealed tube. The candidate material was identified by de novo sequence using mass spectrometry and Edman degradation methods. The content of insulin-related impurities, aggregation, moisture, volatile organic compounds (VOCs), anions, and ignition residues was also determined. Both mass balance (MB) and amino acid analysis-based isotope dilution mass spectrometry (AAA-IDMS) were used for the certified value assessment, which was determined to be (0.857 ± 0.024) g/g. The certified value was validated by liquid chromatography-circular dichroism spectroscopy (LC-CD) and quantitative nuclear magnetic resonance (qNMR) methods, which were in good agreement. No inhomogeneity was observed during a homogeneity examination. A stability examination showed that the CRM was stable for at least 12months when stored at - 70°C, and for 7days when stored at 4, 25, or 40°C. The CRM is expected to be used as a primary calibrator for matrix insulin CRM development and for quality control in biopharmaceutical production and clinical diagnostics.

Structural basis of lignocellulose deconstruction by the wood-feeding anobiid beetle Nicobium hirtum

The details of the lignocellulose deconstruction processes in the digestive systems of wood-feeding insects remain elusive. This study aimed to examine the biochemical conversion of lignocellulose in the digestive system of a wood-feeding anobiid beetle, Nicobium hirtum, one of the most important pests of wooden products in Japan. To this end, N. hirtum larvae were fed with Japanese red pine (softwood) and Japanese beech (hardwood) sapwood diets, as well as an artificial diet containing Shorea wood (hardwood) sapwood sawdust. The structural differences between the original and digested (feces) lignocellulose samples were examined using wet-chemical and two-dimensional (2D) nuclear magnetic resonance (NMR) methods. Cellulose and hemicelluloses, especially mannan in the softwood diet, were preferentially degraded over lignin in the larval digestive system. As a result, lignin was enriched in the digested lignocellulose residues. Lignin compositional analyses based on thioacidolysis and 2D NMR determined that the proportions of oxidized lignin aromatic units were notably increased after digestion. Further, the 2D NMR analyses revealed the accumulation of aldehyde and hydroxypropiovanillone/syringone end-unit structures in lignin, indicating that oxidative and/or reductive modifications of lignin polymers occur in the larval digestive system. Such structural alterations of lignin may facilitate the dissociation of the lignin barrier, thereby liberating polysaccharides for subsequent enzymatic conversion for assimilation and energy.

Time dependency and similarity of gas permeability of concrete in simulated environment

It is of great significance to establish the similarity for time-dependent permeability between simulated environment and natural environment for predicting the time-dependent permeability in practical engineering. Based on the exposure test of ordinary concrete in natural tidal environment and simulated environment, the time-dependent intrinsic gas permeability coefficients (Kg) of concrete were analyzed, and the influence of w/c ratio on Kg and age reduction factor of gas permeability coefficient (mg) was studied. According to the relaxation time tracked by the nuclear magnetic resonance (NMR) method, the time-dependent microstructure parameters of concrete in the natural and simulated environments, such as porosity, pore size distribution, capillary pores porosity, critical pore diameter (Dcd) and mean pore diameter (Dmd) were analyzed. Then, the relationship between the time-dependent gas permeability and microstructure parameters was discussed. Results show that Kg decreased with the increasing exposure time and decreasing w/c ratio. The value of mg decreases with the increasing w/c ratio, and for concrete with the same w/c ratio, mg in the simulated environment is larger than that in the natural tidal environment. Porosity, capillary pores porosity and Dcd of concrete all decrease with exposure time, and have good correlations with gas permeability coefficient (KA) of concrete. Meanwhile, ambient environment has little influence on the correlation between gas permeability and Dcd. At last, based on the similarity between Kg and microstructure parameters in the natural and simulated environments, the rationality of calculating the long-term Kg in natural environment from the short-term results in the simulated environment is verified.

NMR as Used in the Russian and Foreign Pharmacopoeias for Quality Control of Medicinal Products

The ongoing development of the Pharmacopoeia of the Eurasian Economic Union and the current trend for harmonisation of the Russian Pharmacopoeia with the world leading pharmacopoeias suggest the necessity of studying how different pharmacopoeias use nuclear magnetic resonance (NMR) for quality control of medicinal products. The aim of the study was to compare the extent of medicine quality characteristics assessed by NMR in the Russian and foreign pharmacopoeias. The review summarises the experience of various national and world pharmacopoeias in using the NMR method for quality control of medicines and certification of pharmacopoeial reference materials. The comparative analysis covered the following quality parameters: active ingredient identification, determination of the composition of non-stoichiometric compounds, determination of the average polymer chain length in polymers and block copolymers, determination of the absolute content of the active ingredient, identification and quantification of impurities, polymorphism, and crystallinity. It was shown that the United States and Japanese Pharmacopoeias are leading the way in introducing the NMR method into pharmacopoeial analysis. There have been some positive trends in the introduction of the NMR method in the State Pharmacopoeia of the Russian Federation as well. It was concluded that changes are needed in the general chapters “Nuclear Magnetic Resonance Spectroscopy” and “Reference Standards” of the State Pharmacopoeia of the Russian Federation, 14th ed. in order to harmonise the texts with those of the Eurasian Pharmacopoeia and the European Pharmacopoeia and to allow for the possibility of direct identification of a substance by complex analysis of NMR spectral data, without comparing the test sample and the reference standard spectra. The NMR method should be included in the list of absolute methods used for determination of purity of primary chemical reference substances during certification.

An NMR-Based Method for Multiphase Methane Characterization in Coals

Discriminating multiphase methane (adsorbed and free phases) in coals is crucial for evaluating the optimal gas recovery strategies of coalbed methane (CBM) reservoirs. However, the existing volumetric-based adsorption isotherm method only provides the final methane adsorption result, limiting real-time dynamic characterization of multiphase methane in the methane adsorption process. In this study, via self-designed nuclear magnetic resonance (NMR) isotherm adsorption experiments, we present a new method to evaluate the dynamic multiphase methane changes in coals. The results indicate that the T2 distributions of methane in coals involve three different peaks, labeled as P1 (T2 < 8 ms), P2 (T2 = 20–300 ms), and P3 (T2 > 300 ms) peaks, corresponding to the adsorbed phase methane, free phase methane between particles, and free phase methane in the sample cell, respectively. The methane adsorption Langmuir volumes calculated from the conventional volumetric-based method qualitatively agree with those obtained from the NMR method, within an allowable limit of approximately ~6.0%. Real-time dynamic characterizations of adsorbed methane show two different adsorption rates: an initial rapid adsorption of methane followed by a long stable state. It can be concluded that the NMR technique can be applied not only for methane adsorption capacity determination, but also for dynamic monitoring of multiphase methane in different experimental situations, such as methane adsorption/desorption and CO2-enhanced CBM.

An experimental study of ultra-high pressure water jet-induced fracture mechanisms and pore size evolution in reservoir rocks

Ultra-high pressure water jets (UHP-WJ) rock breaking is a promising technology for developing unconventional natural gas reserves . In this study, rock-breaking experiments were conducted using typical reservoir rock samples such as sandstone , shale, and coal. The failure patterns in rocks after impact by UHP-WJ were analyzed. Moreover, the 3D damage field model of the rock was reconstructed based on CT scanning, and the internal crack distribution was visualized and examined. Furthermore, the fracture mechanisms of three types of reservoir rocks under the UHP-WJ impingement were studied. The results indicate that intergranular fractures produced due to shear stress are the dominant type of fracture in sandstones, tensile failure due to stress wave was the main type of fracture observed in shale, and coal exhibited the double breaking characteristics of stress wave effect and water wedge effect. The fragments size distribution of samples shows the largest fragments in shale, followed by coal, and the smallest fragments are observed in sandstone. Finally, the evolution of rock pore structure before and after the impact of UHP-WJ was monitored by nuclear magnetic resonance (NMR) methods. The results reveal that the micropores transform into mesopores and macropores in the sandstone, where the total porosity increased by 14.3%–24.8%. As the jet pressure exceeds 100 MPa, the porosity of shale increases significantly, such that the total porosity of the shale sample increased by 7.6%–37.1%. The mesopores transform into macropores and fractures with the influence of the water wedge effect in coal samples, resulting in the reduction of mesopores and the increase of macropores, where the total porosity of the coal sample increased by 14.6%–40%. The complexity and heterogeneity of pores were reduced under UHP-WJ with the increasing jet pressure. The findings provide a theoretical reference for optimizing the recovery from unconventional natural gas reservoirs .

SI-traceable purity assignment of volatile material ethylbenzene by quantitative nuclear magnetic resonance spectroscopy.

In this study, a quantitative nuclear magnetic resonance (qNMR) method was developed to assign the SI-traceable purity of ethylbenzene, a volatile material, which is a colorless flammable liquid hydrocarbon at room temperature. An ethanol certified reference material having a similar boiling point was used as an internal standard to avoid measurement error arising from the volatilization of ethylbenzene. The reference value of the ethylbenzene study material was obtained by the mass balance method by subtracting all the impurities including water, inorganic impurities, and structurally related impurities (e.g. acetophenone, benzene, isobutylbenzene, sec-butylbenzene, methylcyclohexane), which is regarded as the traditional approach for purity assignment for organic compounds. The results of qNMR showed that the purity of the ethylbenzene study material was 998.6 ± 3.8mg/g at a 95% confidence interval, which was consistent with the reference value of 998.9 ± 1.3mg/g.

Dynamics of Cations around DNA and Protein as Revealed by 23Na Diffusion NMR Spectroscopy

Counterions are vital for the structure and function of biomolecules. However, the behavior of counterions remains elusive due to the difficulty in characterizing mobile ions. Here, we demonstrate that the dynamics of cations around biological macromolecules can be revealed by 23Na diffusion nuclear magnetic resonance (NMR) spectroscopy. NMR probe hardware capable of generating strong magnetic field gradients enables 23Na NMR-based diffusion measurements for Na+ ions in solutions of biological macromolecules and their complexes. The dynamic properties of Na+ ions interacting with the macromolecules can be investigated using apparent 23Na diffusion coefficients measured under various conditions. Our diffusion data clearly show that Na+ ions retain high mobility within the ion atmosphere around DNA. The 23Na diffusion NMR method also permits direct observation of the release of Na+ ions from nucleic acids upon protein–nucleic acid association. The entropy change due to the ion release can be estimated from the diffusion data.

Pore throat characterization of bioturbated heterogeneous sandstone, Bhuj Formation, Kachchh India: An integrated analysis using NMR and HPMI studies

Nuclear magnetic resonance (NMR) relaxometry and high-pressure mercury intrusion (HPMI) are substantially utilized techniques to characterize the inherent heterogeneity of reservoirs. Bioturbation is one such type of microscale heterogeneity that provides challenges to optimal recovery planning and volumetric estimation of hydrocarbon reserves. A comprehensive approach is determined by acknowledging the applicability and limitation of each method. Due to the wide variation in petrophysical properties resulting from the effect of bioturbation, the sample size ranges from mm to cm; hence, a proper methodology needs to be formulated. The present study extends the available method of generating pseudo Pc curves from NMR studies to analyze the effect of multiscale bioturbation heterogeneity. The samples were chosen from two different classes on a bioturbation scale referred to as the bioturbation index (BI) ranging from 0 to 6, 0 being 0% bioturbation and 6 meaning 100% bioturbation. The results indicate that lower BI samples had unimodal behavior, while the higher BI sample had bimodal characteristics in pore network distribution. Increased anisotropy was evident in the higher BI samples, and the HPMI study revealed a contrasting nature of pore throat connectivity with a lower threshold and displacement pressure and an increased median throat diameter in the bioturbated part compared with the nonbioturbated. The bioturbated volume essentially had better and less tortuous pore throat connectivity. The effects of bioturbation were identifiable in a core-scale study using NMR. The bimodal characteristic behavior with two distinct pore throat classes with the larger throat class as dominant claims the bioturbation-assisted pore throat connectivity established in them. The purpose of the paper is to investigate pore throat distribution in bioturbated or heterogeneous reservoirs by integrating NMR and HPMI methods. This study proposes a method that can correlate NMR responses from logging into pore throat distribution in bioturbated zones of the reservoir.

Dynamics of Glyceline and Interactions of Constituents: A Multitechnique NMR Study.

The dynamics of the organic components of the deep eutectic solvent (DES) glyceline are analyzed using an array of complementary nuclear magnetic resonance (NMR) methods. Fast-field cycling 1H relaxometry, pulsed field gradient diffusion, nuclear overhauser effect spectroscopy (NOESY), 13C NMR relaxation, and pressure-dependent NMR experiments are deployed to sample a range of frequencies and modes of motion of the glycerol and choline components of the DES. Generally, translational and rotational diffusion of glycerol are more rapid than those of choline while short-range rotational motions observed from 13C relaxation indicate slow local motion of glycerol at low choline chloride (ChCl) content. The rates of glycerol and choline local motions become more similar at higher ChCl. This result taken together with pressure-dependent NMR studies show that the addition of ChCl makes it easier to disrupt glycerol packing. Finally, a relatively slow hydroxyl H-exchange process between glycerol and choline protons is deduced from the data. Consistent with this, NOESY results indicate relatively little direct H-bonding between glycerol and choline. These results suggest that the glycerol H-bonding network is disrupted as choline is added, but primarily in regions where there is intimate mixing of the two components. Thus, the local dynamics of most of the glycerol resembles that of pure glycerol until substantial choline chloride is present.

Varying Synthesis Conditions and Comprehensive Characterization of Fluorine-Doped Hydroxyapatite Nanocrystals in a Simulated Body Fluid

Bone supports animal bodies, is the place where blood is produced, and is essential for the immune system, among other important functions. The dominant inorganic component in bone is hydroxyapatite (Hap), the structure and dynamics of which still pose many unsolved puzzles. An updated understanding of HAp is of great significance to osteology, dentistry, and the development of artificial bone and other biomaterials. In this work, HAp nanoparticles were synthesized with the wet chemical precipitation method and their structure and morphologies were controlled by varying pH and adding fluoride ions by two different routes: (1) fluoride ions were added during synthesis, and (2) fluoride ions were introduced after the samples were synthesized by soaking the samples in solutions with fluoride ions. XRD and HRTEM were employed to confirm the composition and structure, while various multinuclear (1H, 19F, 31P) solid-state nuclear magnetic resonance (NMR) methods including 1D single pulse, cross-polarization under magic-angle spinning (CPMAS), and 2D heteronuclear correlation (HETCOR) were used to characterize the structure, morphology, and dynamics, validating the general core-shell morphology in these F-HAp samples. It was found that all hydroxide ions were substituted when the fluoride ion concentration was above 0.005 M. An NMR peak corresponding to water structure emerged and the bulk water peak was shifted upfield, indicating that fluoride substitution modifies both the crystalline core and the amorphous shell of F-HAp nanoparticles. With the second route of fluoride substitution, increases in soaking time or fluoride ion concentration could increase fluoride substitution in HAp, but could not achieve complete substitution. Finally, with 1H-31P CPMAS and HETCOR, it was established that there are two types of phosphorous, one in the crystalline core (PO43−) and the other in the amorphous shell (HPO42−). These results are valuable for clarifying the fluoride substitution mechanism in HAp in biomaterials or in organisms, and provide insights for developing next generation replacement materials for bone, tooth, or coating films, drug delivery systems, etc.

Large Chaperone Complexes Through the Lens of Nuclear Magnetic Resonance Spectroscopy.

Molecular chaperones are the guardians of the proteome inside the cell. Chaperones recognize and bind unfolded or misfolded substrates, thereby preventing further aggregation; promoting correct protein folding; and, in some instances, even disaggregating already formed aggregates. Chaperones perform their function by means of an array of weak protein-protein interactions that take place over a wide range of timescales and are therefore invisible to structural techniques dependent upon the availability of highly homogeneous samples. Nuclear magnetic resonance (NMR) spectroscopy, however, is ideally suited to study dynamic, rapidly interconverting conformational states and protein-protein interactions in solution, even if these involve a high-molecular-weight component. In this review, we give a brief overview of the principles used by chaperones to bind their client proteins and describe NMR methods that have emerged as valuable tools to probe chaperone-substrate and chaperone-chaperone interactions. We then focus on a few systems for which the application of these methods has greatly increased our understanding of the mechanisms underlying chaperone functions.

Crystal structures of alphavirus nonstructural protein 4 (nsP4) reveal an intrinsically dynamic RNA-dependent RNA polymerase fold.

Alphaviruses such as Ross River virus (RRV), chikungunya virus (CHIKV), Sindbis virus (SINV), and Venezuelan equine encephalitis virus (VEEV) are mosquito-borne pathogens that can cause arthritis or encephalitis diseases. Nonstructural protein 4 (nsP4) of alphaviruses possesses RNA-dependent RNA polymerase (RdRp) activity essential for viral RNA replication. No 3D structure has been available for nsP4 of any alphaviruses despite its importance for understanding alphaviral RNA replication and for the design of antiviral drugs. Here, we report crystal structures of the RdRp domain of nsP4 from both RRV and SINV determined at resolutions of 2.6 Å and 1.9 Å. The structure of the alphavirus RdRp domain appears most closely related to RdRps from pestiviruses, noroviruses, and picornaviruses. Hydrogen-deuterium exchange mass spectrometry (HDX-MS) and nuclear magnetic resonance (NMR) methods showed that in solution, nsP4 is highly dynamic with an intrinsically disordered N-terminal domain. Both full-length nsP4 and the RdRp domain were capable to catalyze RNA polymerization. Structure-guided mutagenesis using a trans-replicase system identified nsP4 regions critical for viral RNA replication.

Изучение физико-химических показателей эмульгаторов и их влияния на процесс образования пищевых эмульсий

Introduction. Modern food science needs new research of food emulsifiers, their composition, properties and effect on the structural characteristics of emulsions. It looks for modern technological solutions on how to select proper emulsifiers and their mixes to produce emulsions with different mass fractions of fat. The research objective was to study the effect of physical and chemical indicators of surfactants on the properties of food emulsions, as well as to develop practical recommendations for the selection of surfactants for various types of products.
 Study objects and methods. The research featured model dairy fat emulsions and laboratory-made vegetable oil, as well as hard and soft mono- and diglycerides of fatty acids and lecithins. The emulsifiers were used to determine the melting point, fatty acid composition, iodine number, and solid triglyceride content at various temperatures. The melting point of emulsifiers was determined by fixing the melting temperature in a capillary oven. To identify the fatty acid composition, the methyl esters of fatty acids were subjected to the chromatogram method. After that, the separated components and their quantity were determined by the area of the peaks. The content of solid triglycerides in the emulsifiers was determined by the method of nuclear magnetic resonance. The hydrophilic-lipophilic balance was obtained from the manufacturer's specifications.
 Results and discussion. The solid mono- and diglycerides appeared to have a high content of stearic and palmitic acids. Oleic acid predominated in soft monoglycerides; unsaturated fatty acids (linolenic and oleic) also predominated in the monoglycerides/lecithin complex emulsifier. Solid monoglycerides had a high content of solid triglycerides at 35°C (82.93%), which correlated with the high melting point (80°C) and the lowest iodine number (3 mg I2/100 g) of all the samples. The optimal ratio of vegetable oil and the emulsifier was defined empirically. The emulsifiers were dissolved in refined deodorized vegetable oil at 5–7°C above the melting point of the emulsifier. The resulting ratios were between 6:1 and 10:1. The samples of creamy vegetable spreads were obtained using the studied emulsifiers and their compositions in different doses and ratios. The crystallization temperature and phase transition time were determined when studying the process of emulsion overcooling. The article introduces a list of technological and physicochemical indicators of emulsifiers: the fatty acid composition, the degree of saturation, the melting point, and the content of solid triglycerides. By finding out the physicochemical parameters of emulsifiers, producers can vary the ratio of the components of emulsifying compositions to achieve the desired properties of food emulsions. The hydrophilic-lipophilic balance also proved to be an important index since the proportion of hydrophilic and hydrophobic groups in surfactants affects the type of emulsions and makes it possible to adjust the fat content of the finished product.
 Conclusion. The research results can expand the theoretical foundations of food emulsions. The article contains scientifically grounded recommendations on how to select optimal surfactants. The research opens up prospects for further studies of emulsifiers and their effect on the quality of finished products.

Solid-State Nuclear Magnetic Resonance as a Tool to Probe the Impact of Mechanical Preprocessing on the Structure and Arrangement of Plant Cell Wall Polymers.

Efficient separation of the plant cell wall polymers during lignocellulose processing has been historically challenging due to insolubility of the polymers and their propensity for recalcitrant reassembly. Methods, such as “lignin first” extraction techniques, have advanced efficient biomass use, but the molecular mechanisms for recalcitrance remain enigmatic. Here, we discuss how solid-state Nuclear Magnetic Resonance (NMR) approaches report on the 3D organization of cellulose, xylan, and lignin in the plant cell wall. Recent results illustrate that the organization of these polymers varies across biomass sources and sample preparation methods, with even minimal physical processing causing significant effects. These structural differences contribute to variable extraction efficiencies for bioproducts after downstream processing. We propose that solid-state NMR methods can be applied to follow biomass processing, providing an understanding of the polymer rearrangements that can lead to poor yields for the desired bioproducts. The utility of the technique is illustrated for mechanical processing using lab-scale vibratory ball milling of Sorghum bicolor.

Synthesis features, structure, magnetometry and NMR spectroscopy of nanowires of various types

Various types of nanowires obtained by matrix synthesis --- homogeneous (from iron) and heterogeneous (layered) --- have been studied. A technique for obtaining arrays of layered nanowires with alternating thin layers of magnetic and non-magnetic metals (Co/Cu, Ni/Cu) has been developed and described. Microscopy methods (SEM and TEM with elemental analysis) have been used to study the topography of the resulting structures, the diameters of nanowires and the thicknesses of individual layers, and the features of interlayer interfaces. Methods of synthesis of nanowires with thin layers and clear boundaries are proposed --- dilution of the electrolyte, use of a reference electrode, control of the leaked charge. Layered nanowires have been studied by magnetometry methods and it has been shown that the magnetic properties of an array of layered nanowires (in particular, the direction of the axis of light magnetization in the Co/Cu-NP array) depend not only on the aspect ratio of the magnetic layer, but also on the ratio of the thickness of the magnetic metal layer to the thickness of a non-magnetic spacer (copper layer). The nuclear magnetic resonance (NMR) method was used to study two types of nanowires. The NMR method (on 59-Co nuclei) studied the layer structures of Co/Cu: it is shown that in nanowires with layers of smaller thickness (and, accordingly, with a large contribution of interfaces), a large proportion of Co atoms coordinated by Cu atoms is observed. The high proportion of atoms coordinated by copper suggests that an admixture of copper enters the cobalt layers. Homogeneous iron nanowires (NMR on 57-Fe nuclei) were compared with bulk iron samples. A shift of the line towards high frequencies (by 0.3 MHz) was detected, indicating an increase in the field by about 0.2 T. A significant broadening of the line and a decrease in the spin-lattice relaxation time may indicate a significant variation in the local magnetic field values. Keywords: nanowires, matrix synthesis, microscopy, elemental analysis, magnetic properties, NMR.

Research on the importance of NMR technology in medicine and other fields

Nuclear magnetic resonance (NMR) spectroscopy was invented and developed over six decades ago as an integral part of the chemical and structural analysis of small molecules, polymers, biomaterials and hybrids. High-resolution nuclear magnetic resonance (NMR) spectroscopy plays a special role. Nuclear magnetic resonance methods are mainly used for the structural analysis of synthetic and biosynthetic organic and organic compounds and natural products, as well as for the identification of one or more components in complex matrices. Nuclear magnetic resonance spectroscopy is also one of the most powerful analytical tools for the qualitative and quantitative analysis in biological fluids of low-molecular-weight autotrophic metabolites produced by medicines and narcotic drugs. There is a growing trend towards the use of high-resolution NMR spectroscopy in food science. In this context, we will focus on the importance of NMR spectroscopy for studying low-molecular-weight organic materials using selected examples. High-resolution nuclear magnetic resonance (NMR) spectroscopy plays a special role.