1H Spectra Research Articles

(R)-3,3,6-Trimethyl-3,3a,4,5-tetrahydro-1H-cyclopenta[c]furan

(R)-3,3,6-trimethyl-3,3a,4,5-tetrahydro-1H-cyclopenta[c]furan was obtained by the acid cyclization of the alcohol (S)-(2-methyl-5-(prop-1-en-2-yl)cyclopent-1-en-1-yl)methanol, which, in turn, is obtained from (R)-limonene. The structure of the new compound was established using NMR spectroscopy (1H, 13C, COSY, HSQC, and HMBC spectra) and high-resolution mass spectrometry. The chemical shifts of the proton and carbon atoms were calculated at the DFT level with a high correlation between the calculated and experimental values.

Anion and Cation Dynamics in Mixed-Anion Hydroborate Na3(BH4)(B12H12): 1H, 11B, and 23Na NMR Studies

Sodium borohydride-closo-hydroborate Na3(BH4)(B12H12) exhibits high room-temperature ionic conductivity and high electrochemical stability. To study the dynamical properties of this mixed-anion compound at the microscopic level, we have measured the 1H, 11B, and 23Na nuclear magnetic resonance spectra and nuclear spin-lattice relaxation rates over the temperature range of 8–573 K. Our 1H and 11B spin-lattice relaxation measurements have revealed two types of reorientational jump motion. The faster motional process attributed to reorientations of the [BH4]− anions is characterized by an activation energy of 159 meV, and the corresponding reorientational jump rate reaches ~108 s−1 near 130 K. The slower process ascribed to reorientations of the larger [B12H12]− anions is characterized by an activation energy of 319 meV, and the corresponding reorientational jump rate reaches ~108 s−1 near 240 K. The results of the 23Na nuclear magnetic resonance measurements are consistent with the fast long-range diffusion of Na+ ions in Na3(BH4)(B12H12). The diffusive jump rate of Na+ is found to reach ~104 s−1 at 300 K and ~8 × 108 s−1 at 530 K. A comparison of these jump rates with the ionic conductivity data suggests the importance of correlations between diffusing ions.

Optimising the acquisition conditions of high information quality low-field NMR signals based on a cutting-edge approach applying information theory and Taguchi's experimental designs – Virgin olive oil as an application example

BackgroundDeveloping a new spectrometric analytical method based on a fingerprinting approach requires optimization of the experimental stage, particularly with novel instruments like benchtop low-field NMR spectrometers. To ensure high-quality LF-NMR spectra before developing the multivariate model, an experimental design to optimize instrument conditions is essential. However, difficult-to-control factors may be critical for optimization. Taguchi methodology addresses these factors to obtain a system robust to variation. This study uses the Taguchi methodology to optimize instrument settings for acquiring high-quality 1H and 13C LF-NMR signals in a short time from virgin olive oil (VOO). ResultsTwo experimental trials (for 1H and 13C signals, respectively) were carried out and analysed to find an optimal and robust combination of instrument settings against changes in two difficult-to-control factors: ambient temperature and small deviations of the NMR tube volume (700 ± 50 μL). The responses to be optimised, run time and spectral information quality, were analysed separately and jointly, as some factors showed opposite behaviour in the effect on the responses. Multiple response analysis based on suitable desirability functions yielded a combination of factors resulting in desirability values above 0.8 for 1H LF-NMR signals and almost 1.0 for 13C LF-NMR signals.In addition, a novel approach to assess the information quality of an analytical signal was proposed, addressing a major challenge in analytical chemistry. By applying information theory and calculating information entropy, this approach demonstrated its potential for selecting the highest quality (i.e. most informative) analytical signals. SignificanceThe acquisition instrument conditions of LF-NMR were successfully optimised using Taguchi methodology to acquire highly informative 1H and 13C spectra in a minimum run time. The importance lies in the future development of non-targeted analytical applications for VOO quality control. In addition, the innovative use of information entropy to a priori assess the signal quality represents a significant advance and proposes a solution to a long-standing challenge in analytical chemistry.

Effect of Prehydrolysis VTMS on the Structure–Property of Silane‐Terminated Polyurethane

ABSTRACTSilane‐terminated Polyurethane (SPU) is in high demand in the sealant and adhesive industries because of its exceptional cohesive strength and excellent adhesive properties. To close a self‐curable SPU resin was synthesized using a two‐step solution polymerization process for 12 h at pH 2.8 using the sol–gel method. Subsequently, the polyurethane prepolymer's NCO moiety was terminated by VTMS silanol to prepare SPU resin. FTIR and liquid state NMR were used to study VTMS hydrolysis in an acidic medium. Explored the effects of VTMS on SPU properties, including crystallinity, Mn and Mw, viscosity, gel fraction, thermal, surface, and mechanical. FTIR and NMR (1H and 13C) spectra confirmed the successful termination of the prepolymer's unreacted diisocyanate with the hydroxyl moiety of silanol. XPS and FTIR were used to analyze the chemical structures of urethane, urea, siloxane, and the hydrogen bonds between SPU moiety. Increased wt% of silanol exhibits increased gel fraction (80%–91%) with a decreased degree of swelling (76%–45%) showing the formation of a cross‐linked structure. Including siloxane in polyurethane showed a synergetic effect, resulting in enhanced thermal stability through reduction of weight loss. The SPU exhibited a three‐stage degradation pattern, accompanied by decreased glass transition temperature and crystallinity. Siloxane enrichment increased SPU surface roughness (Rq‐218 and Ra‐69 nm) and hydrophobicity (94°–103°). Silane wt% increase causes significant changes in Young's (2.19–51 N/mm2) modulus, strain %, and adhesive strength (4.60–5.62 MPa). Silane‐terminated polyurethane can be used successfully as an adhesive and sealant.

A density functional theory study of a series of symmetric dibenzylideneacetone analogues as potential chemical UV-filters

The aim of this research was to provide valuable insights on symmetrical α,β-unsaturated ketones as potential chemical ultraviolet (UV) filters from experimental data and theoretical aspects. Towards this end, density functional theory (DFT/B3LYP) calculations on a series of symmetrical α,β-unsaturated ketones, (1E,4E)-1,5-bis[4-(R)phenyl]penta-1,4-diene-3-one (R = methylthio, 1; R = dimethylamino, 2; R = ethyl, 3), were performed to determine the effect of different electron-donating substituents on their stability when exposed to solar UV radiation. Their molecular structures, and UV-visible, infrared (IR) and NMR (1H and 13C) spectra were theoretically obtained from their optimized geometries with the B3LYP/6-311++ G (d, p) basis set and were compared with the experimental results. Conformational analysis was performed and the most stable conformer of each compound was identified as the trans-trans conformer, which was further supported by experimental NMR data. The UV spectra and effect of solvent polarity and proticity were studied by the time-dependent-DFT (TD-DFT) approach with the B3LYP/6-311++G (d, p) level of theory. Furthermore, various molecular parameters like dipole moment, frontier molecular orbital (FMO) energies, ΔEHOMO-LUMO gap, lifetime of the first excited state (τ), global chemical reactivity descriptors, and natural bond orbital analysis were predicted at the same level of theory and compared with the experimental data. Inspection of the active FMOs revealed the photoinstability trends of 1 and 3 under UV irradiation. However, introducing a -N(CH3)2 substituent to 2 at the para-position improves its photostability towards simulated UV radiation. Thus, compound 2 has the potential to provide efficient broad-spectrum protection against UV radiation. This work has shown that molecular modelling strategies can assist to rationalize experimental findings and also support the identification of photoproducts of 1 and 3.

Exploring the cyclization of thiosemicarbazone to 1,3,4-thiadiazole: Synthesis, characterization and in-silico study

Breast cancer remains a significant health concern worldwide, necessitating the development of novel therapeutic strategies. In this study, we focus on the design, synthesis, and evaluation of isophorone-1,3,4-thiadiazoles as potential inhibitors targeting AKT1 and STAT3, crucial players in breast cancer progression. The synthesized compounds were rigorously characterized using High-Resolution Mass Spectrometry (HRMS) and Nuclear Magnetic Resonance (NMR) spectroscopy, encompassing both 1H and 13C spectra. Subsequently, Network pharmacology analysis facilitated for the identification of key genes and pathways associated with breast cancer, thereby identifying AKT1 and STAT3 as promising therapeutic targets for the designed compounds. Furthermore, the top two targets, AKT1 and STAT3, were chosen for molecular docking analyses to forecast the binding affinity of the ligands with the proteins, revealing favorable interactions between compounds 8a-c and these targets. Molecular dynamics was performed for 100 ns simulation to predict the stability of the compounds. Acceptable RMSD and RMSF values for amino acid residues indicated structural integrity and a stable protein-ligand interaction. Additionally, all designed compounds displayed favorable physicochemical properties and promising ADMET profiles. These 8a and 8c considered as promising leads for targeting AKT1 and STAT3.

Higher Order Structure Differences Among Insulin Crystalline Drugs Revealed by 2D heteronuclear NMR.

During therapeutic protein development, two-dimensional (2D) heteronuclear NMR spectra can be a powerful analytical method for measuring protein higher order structure (HOS) in solution since the spectra exhibit much higher resolution than homonuclear 1H spectra. However, 2D NMR capabilities for characterizing protein HOS in crystalline states remain to be assessed, given the low 13C natural abundance and intrinsically broader lines in solid-state NMR (SSNMR). Herein, high-resolution heteronuclear correlation (HETCOR) SSNMR was utilized to directly measure intact crystal drug products of insulin human, insulin analogs of insulin lispro and insulin aspart. The fingerprint regions in 2D 1H-13C HETCOR spectra were identified, which distinguished the insulin crystals in their primary structure, HOS heterogeneity and dynamics, as well as the manufacturing processes. The HOS heterogeneity in insulin analogs is consistent with their therapeutic effect of rapid action; while insulin human crystals showed more structural homogeneity, consistent with their slower pharmacokinetics (PK)peak time than insulin analogs. Therefore, heteronuclear NMR could be broadly applicable to study protein drug dosage forms from liquid to solid, yielding improved molecular level structure data for assessing drug HOS in biosimilar drug development.

Integrating strategy to investigate the formation and stabilization mechanisms of Curcumin-Cyclodextrin inclusion complexes: experimental characterizations and multi-scale computational simulations.

The Cyclodextrin (CD) encapsulation technology can significantly enhance the water solubility of Curcumin (CUR) and effectively protect it against chemical degradations. In the current study, a combination of experimental and multi-scale computational approaches was used to investigate the binding mechanism between CUR and β-CDs (β-CD, 2-HP-β-CD, Me-β-CD, and DM-β-CD). Phase solubility studies showed that β-CDs exhibited a strong binding affinity with CUR and significantly enhanced its solubility. SEM, PXRD, DSC, and TG analysis confirmed the formation of inclusion complexes, resulting in the transition of CUR from crystalline to an amorphous state. FTIR, 1H, and 13CNMR spectra deduced that CUR may have multiple binding conformations with β-CDs. The rationality of molecular dynamics simulation systems was confirmed by comparing the simulated IR spectrum from quantum mechanics with the experimental IR spectrum. MM-PBSA and umbrella sampling simulation calculated the binding free energy of the CUR/CD inclusion complexes, ranking Me-β-CD > DM-β-CD > 2-HP-β-CD > β-CD, and clarified that van der Waals interaction played a major role in stabilizing the inclusion complexes. RDF analysis confirmed that the release of high-energy water molecules drove the formation of the CUR/CD inclusion complex, and the β-CD substituents affected their exterior hydration layer. Additionally, principal component analysis (PCA) and non-covalent interaction analysis revealed three CUR/CD binding modes: bead-on-string, terminal insertion, and V-shaped-folding. The research strategy adopted here can serve as a paradigm for investigating the encapsulation mechanism of poorly soluble drugs with CDs.

Metabolic Choreography of Energy Substrates During DCD Heart Perfusion.

The number of patients waiting for heart transplant far exceeds the number of hearts available. Donation after circulatory death (DCD) combined with machine perfusion can increase the number of transplantable hearts by as much as 48%. Emerging studies also suggest machine perfusion could enable allograft "reconditioning" to optimize outcomes. However, a detailed understanding of the energetic substrates and metabolic changes during perfusion is lacking. Metabolites were analyzed using 1-dimensional 1H and 2-dimensional 13C-1H heteronuclear spectrum quantum correlation nuclear magnetic resonance spectroscopy on serial perfusate samples (N = 98) from 32 DCD hearts that were successfully transplanted. Wilcoxon signed-rank and Kruskal-Wallis tests were used to test for significant differences in metabolite resonances during perfusion and network analysis was used to uncover altered metabolic pathways. Metabolite differences were observed comparing baseline perfusate to samples from hearts at time points 1-2, 3-4, and 5-6 h of perfusion and all pairwise combinations. Among the most significant changes observed were a steady decrease in fatty acids and succinate and an increase in amino acids, especially alanine, glutamine, and glycine. This core set of metabolites was also altered in a DCD porcine model perfused with a nonblood-based perfusate. Temporal metabolic changes were identified during ex vivo perfusion of DCD hearts. Fatty acids, which are normally the predominant myocardial energy source, are rapidly depleted, while amino acids such as alanine, glutamine, and glycine increase. We also noted depletion of ketone, β-hydroxybutyric acid, which is known to have cardioprotective properties. Collectively, these results suggest a shift in energy substrates and provide a basis to design optimal preservation techniques during perfusion.

Osmotic dehydration with different agents induced pectin diversity: Physicochemical and structural properties of pectin from instant controlled pressure drop dried peach chips

Pectin as an important cell wall matrix that can be affected by osmotic dehydration (OD) pretreatment, determines the texture characteristics of dried fruit and vegetable products. This study investigated the effect of OD on the structural, thermal and rheological properties of pectin extracted from peach chips prepared by instant controlled pressure drop (DIC) drying. In detail, erythritol, glucose, and trehalose were selected as the osmotic agents (300 g/L). Pectin extracted from Ery-OD samples with a loose structure presented the highest molecular weight (432.9 kDa). The lowest content of arabinose (155.16 mg/g) and galactose (32.80 mg/g) were obtained in Glc-OD samples. With the infiltration of trehalose, the thermal stability of pectin was improved, which contributed to the uniform and complete network structure of pectin. 1H and 13C spectra analysis showed the significant alteration in pectin molecular structure induced by OD pretreatments, which affected the shear thinning behavior of pectin solution. Overall, the type of osmotic agents played a crucial role in the structural, thermal and rheological properties of pectin, which could reflect on the macro-texture characteristics of peach chips. This study would provide a theoretical basis for revealing the effect mechanism of OD on the texture of DIC fruit and vegetable chips at molecular level.

Complete 1H and 13C NMR assignment of cellulose oligomer in LiCl/DMSO

High-resolution solution-state 1H, 13C, and various 2D nuclear magnetic resonance (NMR) spectra of cellulose were obtained using cellulose oligomer dissolved in LiCl/dimethyl sulfoxide, which enabled the assignment of all 1H and 13C resonances. The observed resonances were classified into four groups of glucose rings, corresponding to internal residue, non-reducing end, and reducing ends with α- and β-anomeric configurations. This assignment included the OH protons, which are difficult to assign in cellulose using other solvent systems. NMR measurements and assignments were performed using different LiCl concentrations because information on the hydroxy protons is important for understanding the interaction between cellulose and the solvent. The resonances from the OH protons shifted downfield with increasing LiCl concentration, suggesting that LiCl was attracted to the hydroxy groups of cellulose in solution. Moreover, the magnitude of the shifts varied depending on the positions of the hydroxy groups, which indicated the regioselectivity of the interaction between LiCl and the cellulose hydroxy groups.Graphical abstract

Investigation of the molecular structure of CHBP, biological activities and SARS-CoV-2 protein binding interaction by molecular and biomolecular spectroscopy approaches

The objective of this investigation is to learn more about the structural, electrical, spectroscopic, and physiochemical characteristics of biologically active cyano-4′-hydroxybiphenyl (CHBP). The title molecule’s optimized conformational analysis was computed using the DFT/B3LYP/6–311++G (d, p) level of theory. The observed wavenumbers were compared with theoretical FT-IR and FT-Raman spectra. 1H and 13C NMR experimental spectra in CDCl3 solution (solvent phase) were recorded and the chemical shift was calculated. NBO analysis was used to examine the transfer of charge as well as the intermolecular and intramolecular bonding of orbitals. The TD-DFT (time-dependent DFT) approach was used to estimate theoretical values for both the gas and solvent (ethanol) in the corresponding transitional research, which was conducted using UV–Vis’s spectra. Energy gap (Eg = 0.26764 eV) implies that the strong potential for charge transfer, and the stability of the CHBP compound. CHBP compound’s has bioactive nature, its drug-likeness and biological properties were evaluated. The predicted topological polar surface area of 44.02 \\AA2 for the molecule falls within the permissible range of < 140 \\AA2. Based on the docking results, the most stable docking score value is −6.84 kcal/mol. In that interaction, MET 165 affects both phenyl rings in a pi-sulphur fashion and a single bond hydrogen with protein moieties GLN 192. This suggests that the pi-alkyl in PRO 168 is a hydroxyl substitutional ring. Our findings demonstrate the CHBP compound is a good inhibitor against the SAR COVID-19 viral protein.

Precision detection of cyanide, fluoride, and hydroxide ions using a new tetraseleno-BODIPY fluorescent sensor

A new chemosensor based on Seleno-BODIPY (4) was designed and synthesized for the rapid and sensitive detection of CN–, F−, and OH– ions in THF, exhibiting ultra-low detection limits of 26.26 nM, 43.05 nM, and 8.64 nM, respectively, through a turn-on fluorescent process. The seleno-funcionalization step was based on a novel methodology developed by our group, allowing direct functionalization of the BODIPY core. This procedure involves a quick reaction utilizing Ph2Se2 as a selenium source, BPO (benzoyl peroxide), and p-TSA (p-toluenesulfonic acid) in acetonitrile, enabling the production of the corresponding chalcogenated BODIPYs containing one to four selenium groups, demonstrating its versatility. The structure of BODIPY 4 was confirmed by HRMS, 1H, 13C, 77Se NMR, and IR spectra, and its photophysical properties were also evaluated. BODIPY 4 was applied to detect CN–, F−, and OH– ions in dual-mode detection (UV–Vis and fluorescence spectra), displaying a ratiometric response. The new probe exhibited a fast response time, visual color change from blue to fluorescent yellow, and high sensitivity and selectivity for these analytes over other selected anions. Mechanistic investigation through mass analysis revealed that the detection of these anions by BODIPY 4 occurs via an Aromatic Nucleophilic Substitution reaction with phenylselenide as the leaving group.

Exploring the role of neutral ligands in modulating the photoluminescence of samarium complexes with 1,1,1,5,5,5-hexafluoro-2,4-pentanedione.

Four eight-coordinated luminescent samarium complexes of type [Sm(hfpd)3L2] and [Sm(hfpd)3L'] [where hfpd = 1,1,1,5,5,5-Hexafluoro-2,4-pentanedione L = tri-octyl-phosphine oxide (TOPO) and L' = 1,10-phenanthroline (phen), neocuproine (neoc) and bathocuproine (bathoc) were synthesized via a stoichiometrically controlled approach. This allows for precise control over the stoichiometry of the complexes, leading to reproducible properties. This investigation focuses on understanding the impact of secondary ligands on the luminescent properties of these complexes. Infrared (IR) spectra provided information about the molecular structures, whereas 1H and 13C nuclear magnetic resonance (NMR) spectra confirmed these structural details along with the coordination of ligands to trivalent Sm ion. The UV-vis spectra revealed the molar absorption coefficient and absorption bands associated with the hfpd ligand and photoluminescence (PL) spectroscopy demonstrated intense orange-red emission (648 nm relative to 4G5/2 → 6H9/2) from the complexes. The Commission Internationale de l'Éclairage (CIE) triangles indicated that the complexes emitted warm orange red light with color coordinates (x, y) ranging from (0.62, 0.36) to (0.40, 0.27). The investigation of the band gap as well as color parameters confirms the utility of these complexes in displays and LEDs.

Deuterium MRI of serine metabolism in mouse models of glioblastoma.

Serine is a major source of one-carbon units needed for the synthesis of nucleotides and the production of intramitochondrial nicotinamide adenine dinucleotide phosphate (NADPH), and it plays an important role in cancer cell proliferation. The aim of this study was to develop a deuterium (2H) MRS imaging method for imaging tumor serine metabolism. Sequential (2H) spectra and spectroscopic images were used to monitor the metabolism of [2,3,3-2H3]serine in patient-derived glioblastoma cells in vitro and in tumors obtained by their orthotopic implantation in mouse brain. [14,14-2H2] 5,10-methylene-tetrahydrofolate, [2H]glycine, [2H]formate, and labeled water were detected in cell suspensions and water labeling in spectroscopic images of tumors. Studies in cells and tumors with variable mitochondrial content and inhibitor studies in cells demonstrated that most of the labeled serine was metabolized in the mitochondria. Water labeling in the cell suspensions was correlated with formate labeling; therefore, water labeling observed in tumors could be used to provide a surrogate measure of flux in the pathway of one-carbon metabolism in vivo. The method has the potential to be used clinically to select patients for treatment with inhibitors of one-carbon metabolism and subsequently to detect their early responses to such treatment.

BIOLOGICAL ACTIVITY OF ISOPROPYLAMINE ANTHRAQUINONE

The aim of the work. To predict the drug-likeness and toxicity using modern web tools of the isopropylaminoanthraquinone compound, as well as to experimentally prove a possible mechanism of antitumor activity. Materials and Methods. For the anthraquinone compound, an in silico drug-likeness and toxicity screening was performed using SwissADME and ProTox II online services. Prediction of the antitumor activity mechanism was analyzed using the US National Cancer Institute (NCI) PRISM service. Results and Discussion. 1-Amino-4-(isopropylamino)-9,10-dioxo-9,10-dihydroanthracene-2-sulfonic acid was synthesized by the reaction of nucleophilic substitution of bromamic acid with isopropylamine, which acted as a nucleoforming agent. The structure of the synthesized derivative (98% yield) was confirmed by 1H, 13C NMR, IR and LC-MS spectra. The studied anthraquinone compound showed satisfactory drug-like characteristics and a low toxicity profile. Conclusions. The obtained results may become a platform for further structural optimization of the identified compound based on anthraquinone with an isopropylamine fragment in the development of modern anticancer drugs.

SYNTHESIS OF NEW γ-LACTONE RING DERIVATIVES CONTAINING PYRIDINE AND TRICONDENSED SYSTEMS

Lactone-pyridone rings contain many biologically active molecules of natural and artificial origin. The molecules contained in these two rings, represented by Cerpegine and its derivatives, will also exhibit high biological activity. It is also necessary to take into account that both natural and synthetic multi-substituted lactones have high biological activity. Thus, research in the field of multi-substituted lactones and further transformations are of particular interest. The synthesis of such systems began with the synthesis of a 2-acetylfuranone ring. In the next step, condensation of ethylcyanoacetate with 2-acetylfuranone by Knewenegel produced 3-substituted lactones, which according to the NMP 1H spectroscopy are a mixture of E and Z isomers. Then, when 3-substituted lactones were heated with dimethylformamide dimethylacetal DMFA/DMA, 3-substituted lactones containing a diene fragment in the structure were obtained. Stereoselective attachment E was detected using the NMR 1H spectrum. Then, under the action of the corresponding amine, the intermolecular substitution reactions produce compounds containing a lactone and pyridine group isolated by a σ-bond (serpegenous compound). Due to the proximity of the cyanide group of the pyridine ring and the fourth blight group of the lactone ring, intramolecular cyclization occurs during heating in the alkaline medium to form new tricondensed systems. Thus, an optimal method of synthesis of serpegenous compounds has been developed. These systems are of interest because in their skeleton they have not only a condensed system but also spirocycles. The connections themselves may be a promise for further exploration. For citation: Hakobyan R.M., Kharatyan L.A., Hayotsyan S.S., Attaryan H.S., Melikyan G.S. Synthesis of new γ-lactone ring derivatives containing pyridine and tricondensed systems. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 7. P. 28-40. DOI: 10.6060/ivkkt.20246707.7068.

Preliminary study of proton magnetic resonance spectroscopy to assess bone marrow adiposity in the third metacarpus or metatarsus in Thoroughbred racehorses.

Magnetic resonance spectroscopy (MRS) has been used to investigate metabolic changes within human bone. It may be possible to use MRS to investigate bone metabolism and fracture risk in the distal third metacarpal/tarsal bone (MC/MTIII) in racehorses. To determine the feasibility of using MRS as a quantitative imaging technique in equine bone by using the 1H spectra for the MC/MTIII to calculate fat content (FC). Observational cross-sectional study. Limbs from Thoroughbred racehorses were collected from horses that died or were subjected to euthanasia on racecourses. Each limb underwent magnetic resonance imaging (MRI) at 3 T followed by single-voxel MRS at three regions of interest (ROI) within MC/MTIII (lateral condyle, medial condyle, proximal bone marrow [PBM]). Percentage FC was calculated at each ROI. Each limb underwent computed tomography (CT) and bone mineral density (BMD) was calculated for the same ROIs. All MR and CT images were graded for sclerosis. Histology slides were graded for sclerosis and proximal marrow space was calculated. Pearson or Spearman correlations were used to assess the relationship between BMD, FC and marrow space. Kruskal-Wallis tests were used to check for differences between sclerosis groups for BMD or FC. Eighteen limbs from 10 horses were included. A negative correlation was identified for mean BMD and FC for the lateral condyle (correlation coefficient = -0.60, p = 0.01) and PBM (correlation coefficient = -0.5, p = 0.04). There was a significant difference between median BMD for different sclerosis grades in the condyles on both MRI and CT. A significant difference in FC was identified between sclerosis groups in the lateral condyle on MRI and CT. Small sample size. 1H Proton MRS is feasible in the equine MC/MTIII. Further work is required to evaluate the use of this technique to predict fracture risk in racehorses.

Dual-Tuned Coaxial-Transmission-Line RF Coils for Hyperpolarized 13C and Deuterium 2H Metabolic MRS Imaging at Ultrahigh Fields.

Information on the metabolism of tissues in healthy and diseased states plays a significant role in the detection and understanding of tumors, neurodegenerative diseases, diabetes, and other metabolic disorders. Hyperpolarized carbon-13 magnetic resonance imaging (13C-HPMRI) and deuterium metabolic imaging (2H-DMI) are two emerging X-nuclei used as practical imaging tools to investigate tissue metabolism. However due to their low gyromagnetic ratios (ɣ13C = 10.7 MHz/T; ɣ2H = 6.5 MHz/T) and natural abundance, such method required a sophisticated dual-tuned radiofrequency (RF) coil. Here, we report a dual-tuned coaxial transmission line (CTL) RF coil agile for metabolite information operating at 7T with independent tuning capability. The design analysis has demonstrated how both resonant frequencies can be individually controlled by simply varying the constituent of the design parameters. Numerical results have demonstrated a broadband tuning range capability, covering most of the X-nucleus signal, especially the 13C and 2H spectra at 7T. Furthermore, in order to validate the feasibility of the proposed design, both dual-tuned 1H/13C and 1H/2H CTLs RF coils are fabricated using a semi-flexible RG-405 .086" coaxial cable and bench test results (scattering parameters and magnetic field efficiency/distribution) are successfully obtained. The proposed dual-tuned RF coils reveal highly effective magnetic field obtained from both proton and heteronuclear signal which is crucial for accurate and detailed imaging. The successful development of this new dual-tuned RF coil technique would provide a tangible and efficient tool for ultrahigh field metabolic MR imaging.

Flexible Polycarbonate and Copoly(Imide-Carbonate)s-Based Frequency Selective Surface for Electromagnetic Shielding Application

Optically transparent polycarbonates (PCs) and Copoly(Imide-Carbonate)s (Co-PICs) were synthesized by the melt polycondenzation method. Rigid (imide) and flexible (-O- and –C(CH3)2−) moieties were incorporated in the structure of bisimide diol comonomer using 4-aminophenol and 4,4′-(4,4′-isopropylidenediphenoxy) bis(phthalic anhydride). The structural properties of synthesized comonomers and polymers were confirmed by 1H, 13C-NMR and FT-IR spectra. Thermal properties of polycarbonates and copolycarbonates were examined using DSC and TG analysis. Thermal properties (glass transition Tg and thermal decomposition (Td) temperature) of copolymers were enhanced without sacrificing properties of BPA-based PC (high transparency, ductility, and processability) by the incorporation of active functional bisimide diol comonomer (5–10 mole %) in the polycarbonate backbone. Different sets of PCs and Co-PICs thin film substrates were prepared by the solvent casting method and used to design frequency selective surface. The proposed flexible FSS offers shielding of 20 dB at 8.8 GHz. In addition, the FSS offers polarization independent operation with its symmetrical unit cell geometry.