Spin-echo NMR Research Articles

Supramolecular structure of epoxy oligomers

AbstractBased on the generalized results of experimental methods for studying the viscosity of oligomers—DSC, electron microscopy, NMR spin echo, x‐ray diffraction analysis, edge wetting angles, laser microinterference, atomic force microscopy, dynamic light scattering, plastic flow—an analysis of the features of the supramolecular organization of melts and solutions of epoxy oligomers was carried out. In terms of thermofluctuation approach, a qualitative assessment of the structural elements forming a macroscopic polymer body is given, and direct morphological evidence of their structure, thermodynamic stability, size evolution with temperature changes and elastic‐strain effects is presented. A mathematical apparatus has been developed to describe the destruction of domains in solutions and melts of oligomers. Analytical equations have been proposed for calculating the time of thermofluctuation relaxation of domains. Based on the analysis of the supramolecular structure of dian epoxy oligomers by transmission electron microscopy and translational mobility of oligomer macromolecules in the high temperature region (Tg + 150°C), it has been suggested that a structure such as “flickering clusters” of free volume elements is formed in the oligomer melts.Highlights Phase diagrams of aromatic and aliphatic epoxy oligomers have been constructed. The influence of molecular weight on the activation energy of diffusion of viscous flow is estimated. It has been shown that the supramolecular structure of epoxy oligomers in the melt contains “flickering clusters.” The lifetime of density fluctuations of epoxy oligomers domains in melts has been calculated.

Diffusion of Peptides and Small Molecules Encapsulated in Lipidic Cubic Phases by Band-Selective Excitation Short Transient 1H PGSE NMR.

In model membrane systems, such as lipidic cubic phases (LCPs), 1H NMR spectra are dominated by resonances from water and lipid molecules. The measurement of translational diffusion of peptides/molecules encapsulated in LCPs using conventional 1H pulsed-gradient spin-echo (PGSE) NMR is, therefore, immensely difficult due to the dynamic range caused by the intense resonance(s) from the surrounding environment. The present study reports the use of a band-selective short transient PGSE sequence, avoiding the perturbation of both hydration water and lipids, for measuring the diffusion of molecules encapsulated within the lipid bilayer and the aqueous channels of LCPs.

Sunflower Origin Identification Based on Multi-Source Information Fusion Technique of Kernel Extreme Learning Machine

This study constructs a model for the rapid identification of the origins of edible sunflower (Helianthus) using Kernel Extreme Learning Machine (KELM) with multi-source information fusion technology. Near-infrared spectroscopy (NIRS) and nuclear magnetic resonance spectroscopy (NMRS) were utilized to analyze 180 sunflower samples from the Xinjiang, Heilongjiang, and Inner Mongolia regions. Initially, the identification models for the origin of sunflowers using NIR and NMR data were compared between two algorithms: the Extreme Learning Machine (ELM) and KELM, combined with various spectral preprocessing methods. The experiment found that the NIR spectral model preprocessed with standard normal variate (SNV) using the KELM algorithm was the most accurate, achieving accuracies of 98.7% in the training set and 97.2% in the test set. The spin-echo NMR spectral model preprocessed with non-local means (NLMs) using the KELM algorithm was the second best, with accuracies of 98.4% in the training set and 96.4% in the test set. To further improve the accuracy of the identification models, innovative sunflower origin identification models were developed based on data layer fusion and feature layer fusion using NIRS and NMRS. In the data layer fusion model, the KELM algorithm model was optimal, achieving a test set accuracy and F1 score of 98.2% and 98.18%, respectively, an improvement of 1.0% over the best single data source model. In the feature layer fusion model, four types of feature-layer information-fusion identification models were established using two feature extraction algorithms, Competitive Adaptive Reweighted Sampling (CARS) and Variable Importance Projection (VIP), combined with joint feature and simple merging feature strategies. The CARS-KELM algorithm combined with the joint feature method was found to be the best, achieving 100% accuracy in both the training and test sets, an improvement of 2.8% over the best single data source model. Identifying the origin of edible sunflower using NIRS and NMRS is demonstrated as feasible by the results. The best single-spectrum sunflower origin identification model was achieved using the KELM algorithm with SNV preprocessing. The feature layer fusion method combining NIRS and NMRS data is suitable for handling the task of sunflower origin identification. This method significantly improves the recognition accuracy of the model compared to a single model, achieving fast and accurate origin identification of edible sunflowers. The research results provide a new method for rapid identification of sunflower origin.

Interaction of Cyclodextrins with Amphiphilic Alternating Cooligomers Possessing the Dense Triazole Backbone.

The interaction of cyclodextrins (CDs) with structure-controlled polymers is expected to provide significant insights into macromolecular recognition. However, the interaction of CDs with structure-controlled polymers has been an underexamined issue of investigation. Herein, alternating amphiphilic cooligomers (oligoCnAH, where n denotes the carbon number of alkyl groups; n = 4, 8, and 12) were synthesized by copper(I)-catalyzed azide-alkyne cycloaddition polymerization of heterodimers of 4-azido-5-hexynoic acid (AH) derivatives carrying N-alkylamide and t-butyl (tBu) ester side chains, followed by hydrolysis of the tBu ester, to study the interaction of CDs with oligoCnAH by 1H NMR, nuclear Overhauser effect spectroscopy, and pulse-field-gradient spin-echo NMR. These NMR studies indicated that αCD interacted with oligoC4AH, αCD and βCD interacted with oligoC8AH, and all CDs interacted with oligoC12AH. Based on the equilibrium models proposed, the binding constants were evaluated for the binary mixtures, which showed interaction. Comparing the interactions of the CDs/oligoC12AH binary mixtures with those of the binary mixtures of CDs and alternating copolymers of sodium maleate and dodecyl vinyl ether (polyC12M), it is concluded that oligoC12AH forms less stable micelles than does polyC12M presumably because of the lower molecular weight, the hydrophilic amide groups in the side chain, and the longer interval between neighboring C12 groups in oligoC12AH.

Development of a technique for determining the viability of dormant organisms in powdered substances

The purposes of pharmaceutical biotechnology and quality control of probiotics containing lyophilized bacterial preparations, as well as the purpose of ensuring biological safety, require methods for rapid determination of the viability of dormant forms. This paper describes an approach to determining the viability of dry powdered substances. Lyophilized powder of Kalanchoe daigermontiana, dry dormant eggs of Artemia salina, and dry powder of Lycopodium sp. spores were proposed as model objects. Suspensions of virus-like particles (VLPs) to SARS-CoV-2 were proposed as a cell-free reference material. The following methods of elemental analysis were used in the study: X-ray fluorescence spectroscopy (XRF) on an energy-dispersive device, atomic absorption spectroscopy with electrothermal atomization, and Zeeman background correction (GZ-AAS). The free water content was determined by NMR spin echo. A new method was also used for recording the kinetics of changes in broadband radio emission in the centimeter and millimeter wavelength ranges, with a measurement duration of up to 20 minutes. Live and inactivated powdered preparations of K. daigermontiana and A. salina were prepared and characterized by elemental composition, water content, and spin-spin relaxation time (T2). For these live and inactivated preparations, it was determined that the flux density of intrinsic thermal radio emission decreases by an order of magnitude with the loss of viability. In the future, the results obtained will allow for a rapid test of the viability of lyophilized therapeutics (from medicinal plants to bacterial mixtures that stabilize the intestinal microflora).
 Keywords: millimeter emission, X-ray fluorescence analysis, NMR spin echo, nanoparticles, powdered substances, medicinal plant raw materials

NMR Spin Echo Study of Domain Wall Pinning in Magnets in Combination with an Additional Magnetic Video-Pulse

NMR Spin Echo Study of Domain Wall Pinning in Magnets in Combination with an Additional Magnetic Video-Pulse

Polymer Dynamics in Glycerol-Water Mixtures.

Velocity correlation spectra (VAS) in binary mixtures of water and glycerol (G/W), obtained by measurements using the modulated gradient spin echo (MGSE) NMR method, were explained by the interactions of water molecules with clusters formed around the hydrophilic glycerol molecule, which drastically change the molecular dynamics and rheology of the mixture. It indicates a thickening of the shear viscosity, which could affect the dynamics of submerged macromolecules. The calculation of the polymer dynamics with the Langevin equations according to the Rouse model, where the friction was replaced by the memory function of the retarded friction, gave the dependence of the dynamics of the polymer on the rate of shear viscous properties of the solvent. The obtained formula was used to calculate the segmental VAS of the polymer when immersed in pure water and in a G/W mixture with 33 vol% glycerol content, taking into account the inverse proportionality between the solvent VAS and friction. The spectrum shows that in the G/W mixture, the fast movements of the polymer segments are strongly inhibited, which creates the conditions for slow processes caused by the internal interaction between the polymer segments, such as interactions that cause disordered polypeptides to spontaneously fold into biologically active protein molecules when immersed in such a solvent.

Zwitter-ionic amphiphilic calixresorcinarenes: Micellization in the bulk solution and non-surface activity

Here the amphiphilic calix[4]resorcinarenes, which form self-associates in an aqueous solution but do not exhibit surface activity, are described. Aqueous solutions of calix[4]resorcinarenes with different zwitter-ionic groups on the upper rim: carboxybetaine (C5-CB, C11-CB, C12OPh-CB), sulfobetaine (C5-SB, C11-SB), hydroxysulfobetaine (C5-hSB, C11-hSB), - and different hydrophobic substituents on the lower rim (pentyl, undecyl, dodecyloxyphenyl) were studied by fluorimetry, Fourier transform pulsed-gradient spin-echo (FT-PGSE) NMR spectroscopy, UV–vis spectroscopy, dynamic light scattering (DLS), and tensiometry. It was found that all macrocycles spontaneously form self-associates in an aqueous solution, but only sulfobetaine and hydroxysulfobetaine calixresorcinarenes with pentyl substituents on the lower rim are surface active. The critical association concentration (CAC) values, which were obtained by different methods, as well as values of averaged hydrodynamic diameter, averaged self-association numbers, solubilizing power, and other parameters of self-association are presented and discussed.

New Network Polymer Electrolytes Based on Ionic Liquid and SiO2 Nanoparticles for Energy Storage Systems.

Elementary processes of electro mass transfer in the nanocomposite polymer electrolyte system by pulse field gradient, spin echo NMR spectroscopy and the high-resolution NMR method together with electrochemical impedance spectroscopy are examined. The new nanocomposite polymer gel electrolytes consisted of polyethylene glycol diacrylate (PEGDA), salt LiBF4 and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4) and SiO2 nanoparticles. Kinetics of the PEGDA matrix formation was studied by isothermal calorimetry. The flexible polymer-ionic liquid films were studied by IRFT spectroscopy, differential scanning calorimetry and temperature gravimetric analysis. The total conductivity in these systems was about 10-4 S cm-1 (-40 °C), 10-3 S cm-1 (25 °C) and 10-2 S cm-1 (100 °C). The method of quantum-chemical modeling of the interaction of SiO2 nanoparticles with ions showed the advantage of the mixed adsorption process, in which a negatively charged surface layer is formed from Li+ BF4- ions on silicon dioxide particles and then from ions of the ionic liquid EMI+ BF4-. These electrolytes are promising for use both in lithium power sources and in supercapacitors. The paper shows preliminary tests of a lithium cell with an organic electrode based on a pentaazapentacene derivative for 110 charge-discharge cycles.

Temperature and Pressure Dependence of the Transport Properties of the Ionic Liquid Triethyloctylphosphonium Bis(trifluoromethanesulfonyl)amide, [P222,8][Tf2N

Viscosities of triethyloctylphosphonium bis(trifluoromethanesulfonyl)amide, [P222,8][Tf2N], are reported as a function of temperature [(273 to 363) K] and pressure (maximum 302 MPa) with a falling-body viscometer together with electrical conductivities (κ) measured by impedance spectroscopy at (283 to 348) K, to 250 MPa maximum pressure. pVT data were determined with a vibrating tube densimeter from (298 to 353) K to 50 MPa. Ion self-diffusion coefficients (DSi) were measured by steady-gradient spin-echo NMR [(313 to 365) K], and densities [(273 to 363) K] were determined with a vibrating tube densimeter, both at atmospheric pressure. The results were correlated with Walden and Stokes–Einstein–Sutherland relations. Velocity cross-correlation coefficients (VCC), distinct diffusion coefficients (DDC) and Laity resistance coefficients (LRC) were calculated from DSi and κ at 0.1 MPa. The DDC and LRC for [P222,8][Tf2N] and the pentyl-substituted analogue, [P222,5][Tf2N], showed differences for cation–cation and cation–anion velocity anti correlations, presumably due to the different cation structures. The high-pressure viscosities were used to predict the pressure dependence of the glass-transition temperature for [P222,5][Tf2N] and [P222,8][Tf2N]. Density scaling was applied to the high-pressure viscosities and conductivities of [P222,8][Tf2N] for comparison with [P222,5][Tf2N]. The scaling parameters are consistent with the theoretical treatment of Knudsen et al. for ionic liquids.

Synthesis of Stereoregular Uniform Oligomers Possessing a Dense 1,2,3-Triazole Backbone

Recent remarkable progress of precision polymerization techniques has allowed researchers to synthesize polymers of controlled molecular weight, tacticity, and monomer sequence with narrow distributions. However, it is still a challenging subject to synthesize uniform polymers and oligomers, which possess specific molecular weight, tacticity, and monomer sequence. Utilizing the advantages of t-butyl 4-azido-5-hexynoate (tBuAH), which we designed recently, for the synthesis of uniform polymers and oligomers, uniform oligomers of different stereoregularities possessing a dense 1,2,3-triazole backbone were synthesized using optically active tBuAH precursors by iterative procedures containing azidation, deprotection of the protecting group, and copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC). The stereoregular uniform oligomers were characterized in the solid state by powder X-ray diffraction (PXRD) and in the solution state by pulse-field-gradient spin-echo (PGSE) NMR, ultraviolet (UV) absorption, and circular dichroism (CD) spectroscopic techniques. While the solubility of stereoregular uniform oligomers was investigated using common organic solvents, gelation was observed for solutions of two octamers of different stereoregularities in some solvents, e.g., toluene, tetrahydrofuran (THF), acetone, and methanol. It is noteworthy that the intermolecular attractive interaction depended on the stereoregularity in aprotic polar solvents, i.e., THF and acetone, presumably because of the different polarities of octamers.

Quantitative Polymer Characterizations with NMR Cryoprobes through Spin Echo NMR Pulse Sequences

Quantitative Polymer Characterizations with NMR Cryoprobes through Spin Echo NMR Pulse Sequences

Confinement Effects on the Ionic Liquid Dynamics in Ionosilica Ionogels: Impact of the Ionosilica Nature and the Host/Guest Ratio

Ionosilica ionogels have been lately introduced as emerging all-ionic designer materials. They consist of an ionic liquid (IL) guest trapped within a solid ionosilica support host. In this work, we investigate the influence of the (i) ionosilica nature and (ii) the ionosilica/IL ratio on the mobility of the confined IL. We report the elaboration of various ionosilica ionogels via a nonhydrolytic sol–gel process, using namely tris(3-(trimethoxysilyl)propyl)amine (TTA), methyl-tris(3-(trimethoxysilyl)propyl)ammonium iodide (MTTA), and tetrakis(3-(trimethoxysilyl)-propyl)ammonium iodide (TKTA) as ionosilica precursors, with the IL butyl-methyl imidazolium bis(trifluoromethanesulfonyl)imide ([BMIM] TFSI). Various ionogels were prepared from different ratios between the ionosilica host and the IL guest. The host/guest interactions, i.e., the change in the conformational contribution of the IL counter-anion, were explored by means of Raman spectroscopy. In addition, the transport properties of the confined species were probed via spin echo solid-state NMR experiments and Complex Impedance Spectroscopy (CIS) measurements. Raman experiments revealed different conformational equilibrium for the TFSI anion in the various ionosilica ionogels, with an increase in the cisoid form compared to the bulk IL due to confinement effects. The TFSI anion seems to experience different degrees of confinement and thus different interactions with the ionosilica scaffold as a function of the investigated parameters. Concomitantly, the 1H spin echo NMR and CIS measurements revealed a significantly higher ionic mobility in the materials synthesized from the tris-trialkoxysilylated ammonium precursor compared to the one synthesized from the tetra-trialkoxysilylated ammonium precursor. These results may reflect stronger host–guest interactions in the latter case related to the higher degree of the network reticulation. All these techniques give concordant results and highlight an effect of the chemical constitution of the ionosilica scaffold and the amount of confined IL on its dynamics within the network.

Chain Confinement and Anomalous Diffusion in the Cross over Regime between Rouse and Reptation.

By neutron spin echo (NSE) and pulsed field gradient (PFG) NMR, we study the dynamics of a polyethylene-oxide melt (PEO) with a molecular weight in the transition regime between Rouse and reptation dynamics. We analyze the data with a Rouse mode analysis allowing for reduced long wavelength Rouse modes amplitudes. For short times, subdiffusive center-of-mass mean square displacement ⟨rcom2(t)⟩ was allowed. This approach captures the NSE data well and provides accurate information on the topological constraints in a chain length regime, where the tube model is inapplicable. As predicted by reptation for the polymer ⟨rcom2(t)⟩, we experimentally found the subdiffusive regime with an exponent close to , which, however, crosses over to Fickian diffusion not at the Rouse time, but at a later time, when the ⟨rcom2(t)⟩ has covered a distance related to the tube diameter.

Long-Range Li-Ion 3D Diffusion in the High-Temperature Hexagonal Phase of LiBH4 Studied by 7Li Pulsed Field Gradient NMR and MD Simulations

Lithium diffusion pathways have been determined in three dimensions using molecular dynamics simulations and 7Li pulsed-field gradient spin-echo (PGSE) NMR diffusometry. Lithium ions arrange in multiple hexagonally arranged and intertwined columns oriented at different angles on (001) surfaces. It has been found that lithium jumps are characterized by zig–zag patterns with the main diffusion tensor axis aligned along the [001] direction. Additional diffusion tensor dimensions appear in the (001) planes through multiple jumps along the [001] direction. The simulation results were confirmed by non-linear spin-echo attenuation in the 7Li PGSE NMR experiment and three-dimensional diffusion model developed for Li+-ion conductivity. The exact values of the main diffusion tensor components D⊥ = (D11 + D22)/2 and D∥ = D33 were derived from the uni-dimensional projection of diffusion tensor under macroscopic powder averaging condition. The single ionic jump in the [001] direction was related to D∥, while translation on the (001) plane required at least two jumps through the zig–zag path and related to D⊥. Lithium diffusion in the [001] direction is faster than that in the (001) planes. The activation energies for D⊥ and D∥ were determined between 105 and 130 °C and varied between 0.47 and 0.51 eV, which suggests that both diffusion coefficients are related to the same mechanism of the jump. Pre-exponential factors for D∥ and D⊥ were also determined and equal to 4.8 × 10–6 m2 s–1 for D∥ and 3.8 × 10–7 m2 s–1 for D⊥, respectively, which confirms that molecular translations between (001) surfaces are not performed in a single jump.

Insight into the Structure of a Comb Copolymer–Surfactant Coacervate from Dynamic Measurements by DOSY NMR and Neutron Spin Echo Spectroscopy

Insight into the Structure of a Comb Copolymer–Surfactant Coacervate from Dynamic Measurements by DOSY NMR and Neutron Spin Echo Spectroscopy

Water diffusion in complex systems measured by PGSENMR using chemical shift selective stimulated echo: Elimination of magnetization exchange effects.

The interpretation of molecular translational diffusion as measured by pulsed gradient spin-echo NMR (PGSENMR) can be complicated by the presence of chemical exchange and/or dipolar cross-relaxation (including relayed cross-relaxation via spin diffusion). The magnitude of influence depends on the kinetics of exchange and/or dipolar cross-relaxation present within the system as well as the PGSENMR sequences chosen for measurements. First, we present an exchange induced zero-crossing phenomenon for signal attenuation of water in lipidic cubic phases (formed by a mixture of monoolein and water) in the presence of pulsed gradients observed using a standard STimulated Echo (STE) sequence. This magnetization exchange induced zero-crossing phenomenon, a pseudo-negative diffraction-like feature, resembles that reported previously for restricted diffusion when locally anisotropic pores are polydisperse or randomly oriented. We then demonstrate the elimination of these exchange and/or dipolar cross-relaxation induced effects with the use of a chemical shift selective STE (CHESS-STE) sequence, adapted from the previously reported band-selective short transient STE sequence, along with results obtained from the bipolar pulse pair STE sequence for comparison. The CHESS-STE sequence introduced here represents a generic form of PGSENMR sequences for obtaining water diffusion coefficients free from the influence of exchange and/or dipolar cross-relaxation in complex systems. It has potential applications in measuring translational diffusion of water in biopolymer mixtures as well as probing the microscopic structure in materials via water restricted diffusion measured by PGSENMR, particularly when the potential presence of exchange/cross-relaxation is of concern.

Gradient NMR Method for Studies of Water Translational Diffusion in Plants.

The review of a retrospective nature shows the stages of development of the spin-echo NMR method with constant and pulsed gradient of the magnetic field (gradient NMR) for the study of water diffusion in plant roots. The history of the initial use of gradient NMR for plants, in which it was not possible to experimentally confirm the bound state of water in cells, is described. The work presents the main ideas on which the technology of measuring diffusion by the spin-echo NMR method is built. Special attention is paid to the manifestations and record of the restricted diffusion phenomenon, permeability of membranes, along with the finite formulae used in real experiments. As examples, it gives the non-trivial results of studies of water transfer in roots through the symplastic system, from cell to cell through intercellular contacts with plasmodesmata, through aquaporins, transfer under the influence of changes in external pressure, and the composition of the gas atmosphere.

Revealing the Surface Structure of CdSe Nanocrystals by Dynamic Nuclear Polarization-Enhanced 77Se and 113Cd Solid-State NMR Spectroscopy.

Dynamic nuclear polarization (DNP) solid-state NMR (SSNMR) spectroscopy was used to obtain detailed surface structures of zinc blende CdSe nanocrystals (NCs) with plate or spheroidal morphologies which are capped by carboxylic acid ligands. 1D 113Cd and 77Se cross-polarization magic angle spinning (CPMAS) NMR spectra revealed distinct signals from Cd and Se atoms on the surface of the NCs, and those residing in bulk-like environments, below the surface. 113Cd cross-polarization magic-angle-turning (CP-MAT) experiments identified CdSe3O, CdSe2O2, and CdSeO3 Cd coordination environments on the surface of the NCs, where the oxygen atoms are presumably from coordinated carboxylate ligands. The sensitivity gain from DNP enabled natural isotopic abundance 2D homonuclear 113Cd-113Cd and 77Se-77Se and heteronuclear 113Cd-77Se scalar correlation solid-state NMR experiments which revealed the connectivity of the Cd and Se atoms. Importantly, 77Se{113Cd} scalar heteronuclear multiple quantum coherence (J-HMQC) experiments were used to selectively measure one-bond 77Se-113Cd scalar coupling constants (1J(77Se, 113Cd)). With knowledge of 1J(77Se, 113Cd), heteronuclear 77Se{113Cd} spin echo (J-resolved) NMR experiments were used to determine the number of Cd atoms bonded to Se atoms and vice versa. The J-resolved experiments directly confirmed that major Cd and Se surface species have CdSe2O2 and SeCd4 stoichiometries, respectively. Considering the crystal structure of zinc blende CdSe and the similarity of the solid-state NMR data for the platelets and spheroids, we conclude that the surface of the spheroidal CdSe NCs is primarily composed of {100} facets. The methods outlined here will generally be applicable to obtain detailed surface structures of various main group semiconductor nanoparticles.

A new formulation for polymer fricke dosimeter and an innovative application of neural network to study dose profile from spin-echo NMR data

Dosimetric systems are used to evaluate absorbed dose and the induced effect caused by irradiation. The choice of dosimetric systems depends on their chemical and physical characteristics and in this study, the chemical Fricke dosimeter was prepared and experimentally tested with Poly(Ethylene Oxide) (PEO), a thermoplastic material. It was provided that the usage of PEO material, a cheap and clean polymer, instead of bovine gelatin, very commonly used in Fricke gel dosimeters, is a promising technological development in dosimetric systems. The improved accuracy of the dose estimation in these systems was demonstrated by comparing the results of ultraviolet–visible spectroscopy (UV-VIS) for the PEO-Fricke dosimeters and the Fricke made of bovine gel. Two sample sets of PEO-Fricke dosimeters were prepared, one set was irradiated with different absolute doses and the other set was prepared with different Fe (III) concentrations. The analyses were performed by using two different algorithms to treat Spin-Echo NMR data. The first methodology uses the single and bi-exponential functions to fit the decay data using the Nonlinear least square (NLLS) with the Levenberg-Marquardt algorithm, providing the relaxation time (T2) values as an average value. The second, more appropriate, consider the problem as a Fredholm integral equation to determine the T2 distribution functions by using Hopfield Neural Network (HNN). The results provide information about the ion-polymer interaction and spatial information of the dosimetric system.