Spinning Nuclear Magnetic Resonance Spectroscopy Research Articles

The composition and structure of n-hexane insoluble-hot benzene soluble fraction and hot benzene insoluble fraction from low temperature coal tar

The composition and structure analysis of coal tar is a very important basic issue. In the process of preparing asphaltenes (insoluble in C5-C7 n-alkanes but soluble in hot benzene, HIBS) according to the definition, it was found that hot benzene insoluble (HIBI) components still exist in the coal tar. It is necessary to carry out in-depth analysis and identification of their compositions and structures, in order to obtain detailed information, which provides a certain guiding significance for the deep processing of coal tar. Their compositions and structures were studied by means of physical and thermo-chemical analysis, including Fourier transform infrared spectroscopy (FTIR), Uv-fluorescence spectroscopy, X-ray photoelectron spectroscopy (XPS), 1H magic angle spinning nuclear magnetic resonance spectroscopy (1H-MAS-NMR), 13C cross polarization/magic angle spinning nuclear magnetic resonance spectroscopy (13C-CP/MAS-NMR), thermogravimetric analysis (TG) and pyrolysis gas chromatography-mass spectroscopy (PY-GC/MS). The results show that: HIBS and HIBI are mainly composed of aromatic compounds, phenolic compounds and heteroatomic compounds, but the forms of these compounds are different. The ring number of the aromatic structure in HIBI is larger than that in HIBS. The main bonding ways of oxygen in HIBS and HIBI include CO, C–O, C–OH, C–O–C and COO–, but the peak positions of those functional groups are slightly offset. There are more COO– in the structure of the latter. Compared with HIBS, HIBI contains more carboxyl hydrogen and more oxygen-bonded hydrogen, thus inferring that HIBI contains more oxygenated compounds. In addition, HIBI has more shorter alkyl side chains.

Clinical applications of breast cancer metabolomics using high-resolution magic angle spinning proton magnetic resonance spectroscopy (HRMAS 1H MRS): systematic scoping review.

Breast cancer is a heterogeneous disease with different prognoses and responses to systemic treatment depending on its molecular characteristics, which makes it imperative to develop new biomarkers for an individualized diagnosis and personalized oncological treatment. Ex vivo high-resolution magic angle spinning proton magnetic resonance spectroscopy (HRMAS 1H MRS) is the most common technique for metabolic quantification in human surgical and biopsy tissue specimens. To perform a review of the current available literature on the clinical applications of HRMAS 1H MRS metabolic analysis in tissue samples of breast cancer patients. This systematic scoping review included original research papers published in the English language in peer-reviewed journals. Study selection was performed independently by two reviewers and preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were followed. The literature search returned 159 studies and 26 papers were included as part of this systematic review. There was considerable variation regarding tissue type, aims, and statistical analysis methods across the different studies. To facilitate the interpretation of the results, the included studies were grouped according to their aims or main outcomes into: feasibility and tumor diagnosis (n = 6); tumor heterogeneity (n = 2); correlation with proteomics/transcriptomics (n = 3); correlation with prognostic factors (n = 11); and response evaluation to NAC (n = 4). There is a lot of potential in including metabolic information of breast cancer tissue obtained with HRMAS 1H MRS. To date, studies show that metabolic concentrations quantified by this technique can be related to the diagnosis, prognosis, and treatment response in breast cancer patients.

Utilization of Calcium Carbide Residue Using Granulated Blast Furnace Slag.

The solidification and stabilization of calcium carbide residue (CCR) using granulated blast furnace slag was investigated in this study. CCR binding in hydrated slag was explored by X-ray diffraction, 29Si and 27Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, and thermodynamic calculations. Mercury intrusion porosimetry and and compressive strength tests assessed the microstructure and mechanical properties of the mixtures of slag and CCR. C-A-S-H gel, ettringite, hemicarbonate, and hydrotalcite were identified as the main phases in the mixture of slag and CCR. The maximum CCR uptake by slag and the highest volume of precipitated solid phases were reached when CCR loading in slag is 7.5% by mass of slag, according to the thermodynamic prediction. This feature is also experimentally observed in the microstructure, which showed an increase in the pore volume at higher CCR loading.

Computationally Guided Discovery of the Sulfide Li3AlS3 in the Li-Al-S Phase Field: Structure and Lithium Conductivity.

With the goal of finding new lithium solid electrolytes by a combined computational–experimental method, the exploration of the Li–Al–O–S phase field resulted in the discovery of a new sulfide Li3AlS3. The structure of the new phase was determined through an approach combining synchrotron X-ray and neutron diffraction with 6Li and 27Al magic-angle spinning nuclear magnetic resonance spectroscopy and revealed to be a highly ordered cationic polyhedral network within a sulfide anion hcp-type sublattice. The originality of the structure relies on the presence of Al2S6 repeating dimer units consisting of two edge-shared Al tetrahedra. We find that, in this structure type consisting of alternating tetrahedral layers with Li-only polyhedra layers, the formation of these dimers is constrained by the Al/S ratio of 1/3. Moreover, by comparing this structure to similar phases such as Li5AlS4 and Li4.4Al0.2Ge0.3S4 ((Al + Ge)/S = 1/4), we discovered that the AlS4 dimers not only influence atomic displacements and Li polyhedral distortions but also determine the overall Li polyhedral arrangement within the hcp lattice, leading to the presence of highly ordered vacancies in both the tetrahedral and Li-only layer. AC impedance measurements revealed a low lithium mobility, which is strongly impacted by the presence of ordered vacancies. Finally, a composition–structure–property relationship understanding was developed to explain the extent of lithium mobility in this structure type.

Impact of Bi2O3 and ZrO2 Radiopacifiers on the Early Hydration and C-S-H Gel Structure of White Portland Cement.

Bismuth oxide (monoclinic α-Bi2O3) and zirconium oxide (monoclinic ZrO2) are the most popular radiopacifiers in commercial Portland cement-based endodontic restoratives, yet their effects on the setting and hydration reactions are not fully understood. This study compares the impact of 20 wt.% of Bi2O3 or ZrO2 on the early hydration reactions and C–S–H gel structure of white Portland cement (WPC). Cement paste samples were hydrated at 37.5 °C prior to analysis by 29Si and 27Al magic angle spinning nuclear magnetic resonance spectroscopy at 3 h and 24 h, and transmission electron microscopy at 3 h. Initial and final setting times were determined using a Vicat apparatus and reaction kinetics were monitored by isothermal conduction calorimetry. Bi2O3 was found to prolong initial and final setting times and retard the degree of hydration by 32% at 24 h. Heat evolution during the acceleration and deceleration phases of the hydration process was reduced and the exotherm arising from renewed ettringite formation was delayed and diminished in the presence of Bi2O3. Conversely, ZrO2 had no significant impact on either setting time; although, it accelerated hydration by 23% within 24 h. Increases in the mean silicate chain length and the extent of aluminum substitution in the C–S–H gel were observed in the presence of both radiopacifying agents after 24 h relative to those of the unblended WPC. The Bi2O3 and ZrO2 particles remained intact within the cement matrix and neither bismuth nor zirconium was chemically incorporated in the hydration products.

In vitro and in vivo osteogenic potential of niobium‐doped 45S5 bioactive glass: A comparative study

In vitro and in vivo experiments were undertaken to evaluate the solubility, apatite-forming ability, cytocompatibility, osteostimulation, and osteoinduction for a series of Nb-containing bioactive glass (BGNb) derived from composition of 45S5 Bioglass. Inductively coupled plasma optical emission spectrometry (ICP-OES) revealed that the rate at which Na, Ca, Si, P, and Nb species are leached from the glass decrease with the increasing concentration of the niobium oxide. The formation of apatite as a function of time in simulated body fluid was monitored by 31P Magic Angle Spinning (MAS) Nuclear magnetic resonance spectroscopy. Results showed that the bioactive glasses: Bioglass 45S5 (BG45S5) and 1 mol%-Nb-containing-bioactive glass (BGSN1) were able to grow apatite layer on their surfaces within 3 h, while glasses with higher concentrations of Nb2 O5 (2.5 and 5 mol%) took at least 12 h. Nb-substituted glasses were shown to be compatible with bone marrow-derived mesenchymal stem cells (BMMSCs). Moreover, the bioactive glass with 1 mol% Nb2 O5 significantly enhanced cell proliferation after 4 days of treatment. Concentrations of 1 and 2.5 mol% Nb2 O5 stimulated osteogenic differentiation of BMMSCs after 21 days of treatment. For the in vivo experiments, trial glass rods were implanted into circular defects in rat tibia in order to evaluate their osteoconductivity and osteostimulation. Two morphometric parameters were analyzed: (a) thickness of new-formed bone layer and (b) area of new-formed subperiostal bone. Results showed that BGNb bioactive glass is osteoconductive and osteostimulative. Therefore, these results indicate that Nb-substituted glass is suitable for biomedical applications.

Hyperoxia affects the lung tissue: A porcine histopathological and metabolite study using five hours of apneic oxygenation

BackgroundOxygen is a liberally dosed medicine; however, too much oxygen can be harmful. In certain situations, treatment with high oxygen concentration is necessary, e.g. after cardiopulmonary resuscitation. The amount of oxygen and duration of hyperoxia causing pulmonary damage is not fully elucidated. The aim of this study was to investigate pathophysiological and metabolite changes in lung tissue during hyperoxia while the lungs were kept open under constant low pressure. MethodsSeven pigs were exposed to 100% oxygen for five hours, using an apneic oxygenation technique with one long uninterrupted inspiration, while carbon dioxide was removed with an interventional lung assist. Arterial blood samples were collected every 30 minutes. Lung biopsies were obtained before and after hyperoxia. Microscopy and high-resolution magic angle spinning nuclear magnetic resonance spectroscopy were used to detect possible pathological and metabolite changes, respectively. Unsupervised multivariate analysis of variance and paired sample tests were performed. A two-tailed p-value ≤ 0.05 was considered significant. ResultsNo significant changes in arterial pH, and partial pressure of carbon dioxide, and no clear histopathological changes were observed after hyperoxia. While blood glucose and lactate levels changed to a minor degree, their levels dropped significantly in the lung after hyperoxia (p ≤ 0.04). Reduced levels of antioxidants (p ≤ 0.05), tricarboxylic acid cycle and energy (p ≤ 0.04) metabolites and increased levels of several amino acids (p ≤ 0.05) were also detected. ConclusionDespite no histological changes, tissue metabolites were altered, indicating that exposure to hyperoxia affects lung tissue matrix on a molecular basis.

What Does Reduced FDG Uptake Mean in High-Grade Gliomas?

As well as in many others cancers, FDG uptake is correlated with the degree of malignancy in gliomas, that is, commonly high FDG uptake in high-grade gliomas. However, in clinical practice, it is not uncommon to observe high-grade gliomas with low FDG uptake. Our aim was to explore the tumor metabolism in 2 populations of high-grade gliomas presenting high or low FDG uptake. High-resolution magic-angle spinning nuclear magnetic resonance spectroscopy was realized on tissue samples from 7 high-grade glioma patients with high FDG uptake and 5 high-grade glioma patients with low FDG uptake. Tumor metabolomics was evaluated from 42 quantified metabolites and compared by network analysis. Whether originating from astrocytes or oligodendrocytes, the high-grade gliomas with low FDG avidity represent a subgroup of high-grade gliomas presenting common characteristics: low aspartate, glutamate, and creatine levels, which are probably related to the impaired electron transport chain in mitochondria; high serine/glycine metabolism and so one-carbon metabolism; low glycerophosphocholine-phosphocholine ratio in membrane metabolism, which is associated with tumor aggressiveness; and finally negative MGMT methylation status. It seems imperative to identify this subgroup of high-grade gliomas with low FDG avidity, which is especially aggressive. Their identification could be important for early detection for a possible personalized treatment, such as antifolate treatment.

Structural and electrical properties of ceramic Li-ion conductors based on Li1.3Al0.3Ti1.7(PO4)3-LiF

The work presents the investigations of Li1.3Al0.3Ti1.7(PO4)3-xLiF Li-ion conducting ceramics with 0 ≤ x ≤ 0.3 by means of X-ray diffractometry (XRD), 7Li, 19F, 27Al and 31P Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) spectroscopy, thermogravimetry (TG), scanning electron microscopy (SEM), impedance spectroscopy (IS) and density method. It has been shown that the total ionic conductivity of both as-prepared and ceramic Li1.3Al0.3Ti1.7(PO4)3 is low due to a grain boundary phase exhibiting high electrical resistance. This phase consists mainly of berlinite crystalline phase as well as some amorphous phase containing Al3+ ions. The electrically resistant phases of the grain boundary decompose during sintering with LiF additive. The processes leading to microstructure changes and their effect on the ionic properties of the materials are discussed in the frame of the brick layer model (BLM). The highest total ionic conductivity at room temperature was measured for LATP-0.1LiF ceramic sintered at 800 °C and was equal to σtot = 1.1 × 10−4 S cm−1.

Field cancerization therapy with ingenol mebutate contributes to restoring skin-metabolism to normal-state in patients with actinic keratosis: a metabolomic analysis

Actinic keratosis (AK) is a skin premalignant lesion, which progresses into squamous cell carcinoma (SCC) if left untreated. Ingenol mebutate gel is approved for local treatment of non-hyperkeratotic, non-hypertrophic AK; it also has the potential to act as a field cancerization therapy to prevent the progression of AK to SCC. To gain better insights into the mechanisms of ingenol mebutate beyond the mere clinical assessment, we investigated, for the first time, the metabolome of skin tissues from patients with AK, before and after ingenol mebutate treatment, with high-resolution magic angle spinning nuclear magnetic resonance spectroscopy. The metabolomic profiles were compared with those of tissues from healthy volunteers. Overall, we identified a number of metabolites, the homeostasis of which became altered during the process of tumorigenesis from healthy skin to AK, and was restored, at least partially, by ingenol mebutate therapy. These metabolites may help to attain a better understanding of keratinocyte metabolism and to unmask the metabolic pathways related to cell proliferation. These results provide helpful information to identify biomarkers with prognostic and therapeutic significance in AK, and suggest that field cancerization therapy with ingenol mebutate may contribute to restore skin metabolism to a normal state in patients with AK.

Supplemental Shimming for HR-μMAS NMR Spectroscopy

Occasionally in proton high-resolution magic angle spinning nuclear magnetic resonance spectroscopy (1H HR-MAS NMR), the standard field shimming across the region-of-interest with the active shims is not sufficient in the presence of substantial magnetic susceptibility gradients. This can be ascribed to the presence of large air pocket within the sample, the proximity between sample and probehead (especially with micro-sized probes), or data acquisition at high magnetic fields. Herein, the study demonstrates a simple approach to enhance the capacity of the shim fields—by supplementing a specific passive ferro-shim—for unifying the field distributions across the sample. Qualitative field numerical analyses were carried out to illustrate the effectiveness of the applied passive shims together with the active shims.

Ex vivo metabolite profiling of paediatric central nervous system tumours reveals prognostic markers

Brain tumours are the most common cause of cancer death in children. Molecular studies have greatly improved our understanding of these tumours but tumour metabolism is underexplored. Metabolites measured in vivo have been reported as prognostic biomarkers of these tumours but analysis of surgically resected tumour tissue allows a more extensive set of metabolites to be measured aiding biomarker discovery and providing validation of in vivo findings. In this study, metabolites were quantified across a range of paediatric brain tumours using 1H-High-Resolution Magic Angle Spinning nuclear magnetic resonance spectroscopy (HR-MAS) and their prognostic potential investigated. HR-MAS was performed on pre-treatment frozen tumour tissue from a single centre. Univariate and multivariate Cox regression was used to examine the ability of metabolites to predict survival. The models were cross validated using C-indices and further validated by splitting the cohort into two. Higher concentrations of glutamine were predictive of a longer overall survival, whilst higher concentrations of lipids were predictive of a shorter overall survival. These metabolites were predictive independent of diagnosis, as demonstrated in multivariate Cox regression models. Whilst accurate quantification of metabolites such as glutamine in vivo is challenging, metabolites show promise as prognostic markers due to development of optimised detection methods and increasing use of 3 T clinical scanners.

Durable BaO–ZnO–P2O5 glass with small stress‐induced birefringence for lead‐free polarization light‐controlling devices

AbstractBarium zinc phosphate glasses formulated in the xBaO–(60 − x)ZnO–40P2O5 composition line are investigated for their optical, thermal, and chemical characteristics. These as well as small stress‐induced birefringence were found to be governed by the BaO/ZnO substitution. In addition to the characterization of the properties, the phosphate network was qualitatively and quantitatively described in terms of Q2 and Q1 ratios by 1D 31P magic angle spinning nuclear magnetic resonance spectroscopy experiments that also showed the presence of Q0 sites. It turns out that the small perturbations of their photoelastic, magnetic, and chemical characteristics made these glasses very good candidates for use in polarization‐controlling optical devices.

Ettringite-based binder from ladle slag and gypsum – The effect of citric acid on fresh and hardened state properties

The retardant effects of citric acid on the properties of ettringite binders are not yet fully understood. This investigation provides insights into the effects of citric acid on both the fresh and hardened state properties of the binder produced from the hydration between ladle slag and gypsum (LSG). The results revealed that LSG's initial setting time could be controlled via different citric acid contents and could range from 20 min to 2 h. Citric acid is effective at relatively high dosages; in its absence, ettringite formed almost immediately directly following exposure to water. The presence of citric acid alters the hydration reactions in LSG. AFm was found to be one of main hydration products; citric acid promoted the conversion from ettringite to monosulfate, detected by using solid-state 27Al magic-angle spinning nuclear magnetic resonance spectroscopy. In addition, citric acid increased the compressive strength of LSG mortars by up to 45%.

Abstract 3721: Improved fitting of HRMAS NMR spectra for ex vivo metabolomic analysis of glioma tissue

Abstract Gliomas are aggressive brain tumors with high rates of treatment resistance and low survival rates. High-resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR) spectroscopy can quantify metabolite concentrations in glioma tissue, but most analysis techniques require manual peak selection and integration that prevents accurate and reliable quantitation of overlapping peaks and large macromolecule baselines. Our goal was to compare the effectiveness of operator-independent LCModel analysis of glioma spectra acquired from free induction decay (FID) and Carr-Purcell-Meiboom-Gill (CPMG) pulse sequences. HRMAS NMR spectra were acquired using FID and CPMG sequences from 14 histologically-confirmed glioma tissue samples (WHO grade II (n=5), III (n=5), and IV (n=4)) collected during surgical resection from human brain tumor patients. Metabolite concentration ratios and Cramer-Rao lower bounds (CRLBs) were estimated using LCModel. Metabolite CRLBs were compared using a paired two sample t-test. Differences in concentrations as a function of WHO grade were determined with ANOVA and Tukey-Kramer post-hoc tests. Significance was determined by p<.05. Metabolite CRLBs for lactate and myo-inositol were significantly lower for CPMG compared to FID spectra (p<.05). Most metabolites could be quantified with LCModel from spectra acquired with CPMG where many metabolites acquired with the FID sequence were not detected. For example, lactate was quantifiable from 3 of the spectra acquired with FID compared to 12 spectra with CPMG. The use of the CPMG sequence reduces quantification errors by eliminating confounding baseline signals. LCModel facilitates improved separation of overlapping resonances compared to manual peak integration, supporting the use of operator-independent methods for metabolic spectral analysis. Comparison of metabolite concentrations as a function of WHO grade revealed significant differences in lactate and glutamine plus glutamate normalized to creatine (p<.05). 2-hydroxyglutarate (2-HG) was also detected in 9 out of 13 isocitrate dehydrogenase (IDH)-mutated samples using both sequences. IDH-mutated tissue should produce 2-HG; however, these results are promising as 2-HG can be difficult to quantify in 1D NMR due to spectral overlap. In conclusion, LCModel can reliably quantify HRMAS spectra acquired with the CPMG sequence but is less reliable with the FID sequence. Increases in lactate and glutamine plus glutamate concentrations as a function of tumor grade were consistent with previous results using HRMAS for glioma metabolic analysis, and 2-HG was detected in 1D HRMAS spectra acquired with both sequences. We expect that improved spectral fitting will contribute to future NMR-based metabolomics studies in glioma. Note: This abstract was not presented at the meeting. Citation Format: Selin Ekici, Ren Geryak, Stewart G. Neill, Hui-Kuo Shu, Candace C. Fleischer. Improved fitting of HRMAS NMR spectra for ex vivo metabolomic analysis of glioma tissue [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3721.

Plutonium and Americium Aluminate Perovskites.

Both AmAlO3 and PuAlO3 perovskites have been synthesized and characterized using powder X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and 27Al magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR). AmAlO3 perovskite showed a rhombohedral configuration (space group R3̅c) in agreement with previous studies. The effect of americium α-decay on this material has been followed by XRD and 27Al MAS NMR analyses. In a first step, a progressive increase in the level of disorder in the crystalline phase was detected, associated with a significant crystallographic swelling of the material. In a second step, the crystalline AmAlO3 perovskite was progressively converted into amorphous AmAlO3, with a total amorphization occurring after 8 months and 2 × 1018 α-decays/g. For the first time, PuAlO3 perovskite was synthesized with an orthorhombic configuration (space group Imma), showing an interesting parallel to CeAlO3 and PrAlO3 lanthanide analogues. High-temperature XRD was performed and showed a Imma → R3̅c phase transition occurring between 473 and 573 K. The thermal behavior of R3̅c PuAlO3 was followed from 573 to 1273 K, and extrapolation of the data suggests that cubic plutonium perovskite should become stable at around 1850 K (R3̅c → Pm3̅m transition).

Low-temperature formation of Pb2OF2 with O/F anion ordering by solid state reaction

The lead oxyfluoride Pb2OF2 was formed by heating a mixture of equimolar PbO and PbF2 at a relatively low temperature of 200 °C in air, suggesting that high ionic diffusion occurs in this reaction at low temperature. The crystal structure of Pb2OF2 was refined by Rietveld analysis using synchrotron X-ray diffraction (SXRD) data and the local structure around fluorine was evaluated by solid state 19F magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. The combination of SXRD and NMR confirmed that oxygen and fluorine ions in Pb2OF2 are in an ordered arrangement. The band gap of Pb2OF2 estimated from the absorption edge (λ = 325 nm) was 3.8 eV. Due to the O/F ordering, the one-dimensional chains of OPb4 tetrahedra along the c-axis of the tetragonal cell were isolated from each other by one-dimensional chains of FPb4 tetrahedra, which makes the band gap greater than that of PbO.

Changes in mineral composition, growth of calcite crystal, and promotion of physico-chemical properties induced by carbonation of β-C2S

Larnite (β-C2S) is a low-calcium mineral with a low rate of early hydration which has a high CO2 sequestration potential. Synthetic β-C2S was exposed to pure CO2 for gas–solid carbonation for varied time periods to investigate changes in mineral composition, calcite crystal growth, and the development of physico-chemical properties. Results show that the ultimate degree of carbonation reached 61.5% and the ultimate CO2 sequestration capacity was 314.7 g/kg raw β-C2S. High-resolution transmission electron microscopy, 13C magic angle spinning nuclear magnetic resonance spectroscopy, the Rietveld method, and thermogravimetric analysis confirmed that amorphous and/or poorly-crystalline calcium carbonates were produced during carbonation. Well-crystalline calcite with a single crystal structure was formed, having a crystallite size of 107 nm and an average particle size of 1.8 μm after 168 h of carbonation. The compact stack and the strong mechanical bond between well-crystalline calcite particles were observed in scanning electron microscopy images, and they are thought to contribute to a strong micro level force, thereby leading to the good macro level performance of carbonation products which reached 127 MPa after 168 h of carbonation. This study contributes to a more insightful understanding of the vital role of calcite in promoting the mechanical and physico-chemical properties of β-C2S-containing wastes and cements produced by carbonation. A further investigation into the micro level mechanical properties of calcite is required to understand the relation between carbonation and increased strength.

Understanding the Effect of UV-Induced Cross-Linking on the Physicochemical Properties of Highly Performing PEO/LiTFSI-Based Polymer Electrolytes.

We report a thorough, multitechnique investigation of the structure and transport properties of a UV-cross-linked polymer electrolyte based on poly(ethylene oxide), tetra(ethylene glycol)dimethyl ether (G4), and lithium bis(trifluoromethane)sulfonimide. The properties of the cross-linked polymer electrolyte are compared to those of a non-cross-linked sample of same composition. The effect of UV-induced cross-linking on the physico/chemical characteristics is evaluated by X-ray diffraction, differential scanning calorimetry, shear rheology, 1H and 7Li magic angle spinning nuclear magnetic resonance (NMR) spectroscopy, 19F and 7Li pulsed field gradient stimulated echo NMR analyses, electrochemical impedance spectroscopy, and Fourier transform Raman spectroscopy. Comprehensive analysis confirms that UV-induced cross-linking is an effective technique to suppress the crystallinity of the polymer matrix and reduce ion aggregation, yielding improved Li+ transport number (>0.5) and ionic conductivity (>0.1 mS cm?1) at ambient temperature, by tailoring the structural/morphological characteristics of the polymer matrix. Finally, the polymer electrolyte allows reversible operation with stable profile for hundreds of cycles upon galvanostatic test at ambient temperature of LiFePO4-based lithium-metal cells, which deliver full capacity at 0.05 or 0.1C current rate and keep high rate capabilities up to 1C. This enforces the role of UV-induced cross-linking in achieving excellent electrochemical characteristics, exploiting a practical, easy up-scalable process.

Thermotropic Liquid Crystalline Polymers with Various Alkoxy Side Groups: Thermal Properties and Molecular Dynamics.

Two series of thermotropic liquid-crystalline polymers (TLCPs) were synthesized by reacting various dialkoxy terephthalate units with hydroquinone (HQ) and 2,6-naphthalene diol (Naph). The dialkoxy terephthalate moieties used in this study include 2,5-diethoxyterephthalate, 2,5-dibutoxyterephthalate, and 2,5-dihexyloxy-terephthalate. All the TLCPs synthesized in this study formed nematic phases. The molecular motions according to the length of the dialkoxy side groups in the TLCPs were evaluated by 13C cross-polarization/magic angle spinning nuclear magnetic resonance spectroscopy. The thermal properties and molecular dynamics of the TLCPs are found to be affected by the length of the dialkoxy side group and the aromatic diol unit in the main chain. Further, the thermal behaviors, liquid crystalline mesophases, and degree of crystallinity of the two series of TLCPs, i.e., HQ- and Naph-TLCPs, are compared.