Food contact paper (FCP) often has polymer treatments applied for grease- and water-resistance. These polymer food contact substances (FCS) are a potential source of dietary exposures to per- and polyfluoroalkyl substances (PFAS). Due to potential health risks associated with exposure to the 6:2 fluorotelomer alcohol (6:2 FTOH), manufacturers committed to phase-out select grease-proofing agents that contain this short-chain PFAS as an impurity in the FCS. This phase-out occurred over a 3-year period which concluded at the end of December 2023. Methods to characterize the fluorine and monitor this phase-out were needed. Prior methodologies employ a hydrolysis step to separate the side-chains and facilitate detection. Fluorine-19 nuclear magnetic resonance spectroscopy (19F NMR) offers many benefits, both as a monitoring technique and as a tool to assess the reaction. Liquid- and solid-state magic angle spinning (MAS) 19F NMR were used to examine the fluorine content in FCP coated with polymers containing 6:2 FTOH. Hydrolysis facilitated the analysis of the 6:2 FTOH by releasing it from the polymer FCS. Solid-state NMR offered information regarding fluorine content before and after hydrolysis that when combined with the liquid-state analysis allows the assessment of the reaction. Deuterated sodium hydroxide at a 1 M concentration was sufficient to release most of the FTOH from the majority of the FCP samples. The hydrolysis protocol combined with liquid- and solid-state NMR proved to be an efficient tool to comprehensively examine the fluorine content present in FCS and will be useful as the market surveillance continues past the phase-out period.

We present a facile, solution-based approach to prepare bulk lithium phosphorus oxynitride (LiPON) utilizing a stepwise reduction between lithium tert-butoxide (LiOtBu) and a phosphazene base, diethyl phosphoramidate (DEPA), which are also precursors used in LiPON synthesis by atomic layer deposition (ALD). The study finds that the two ALD LiPON precursors can readily react upon mixing in THF at room temperature, which yields an ionically conductive solid powder that may be used as a solid-state electrolyte in solid-state batteries or as a material for surface coating. We conducted comprehensive characterization studies using solid-state nuclear magnetic resonance (SSNMR) spectroscopy, cryogenic transmission electron microscopy (cryo-TEM), matrix-assisted laser desorption ionization mass spectroscopy (MALDI-MS), X-ray diffraction spectroscopy (XRD), and X-ray photoelectron spectroscopy (XPS) to study the structure of this bulk LiPON material, which exhibits a composition closely resembling LiPO2N. We propose a reaction mechanism of this bulk synthesized LiPON in a solution system.

Chemically modified nucleic acid molecules have been developed as oligonucleotide therapeutics, and its assay is critical in quality assurance. The common DNA/RNA quantification method using UV-260 nm can lack accuracy because of structure modifications and the possible formation of higher-order structure (HOS). Additionally, process-associated water and counterions affect the accuracy in gravimetric analysis. Thus, to improve accuracy, efficiency, and flexibility, in this work a fast (<1 h) externally referenced 31P quantitative-NMR (qNMR) method was developed. The qNMR assay results agreed within 1-5% of the UV-260 nm results for the single-stranded DNA standards, confirming the method accuracy. Next, an NMR and UV comparison study was performed on intact oligonucleotide drug products. The P-31 qNMR method showed 7 +/- 2%, 8 +/- 1%, and 12 +/- 1% lower concentration values compared with drug product labels for eteplirsen, inotersen, and inclisiran, respectively. Meanwhile the UV-260 nm results showed 28 +/- 3%, 10 +/- 3%, and 10 +/- 1% lower concentrations than the label for the same three drugs. The agreement between NMR and UV for phosphorothioate (PS)-based inotersen and mostly phosphodiester (PO)-based inclisiran suggest that the labeled concentration may have been obtained using different extinction coefficients. The underestimate of UV results for eteplirsen, which has a phosphorodiamidate morpholino oligomer (PMO) structure, suggests that the UV-260 nm extinction coefficient may need to be re-established for the PMO based oligonucleotide. Therefore, the P-31 qNMR method could be a primary assay method for the oligonucleotide drug and reference standard.

Diapause (D) is a hormonally controlled alternative developmental pathway that allows mosquitoes to survive harsh winter conditions. Key characteristics of mosquito diapause include elevated lipid storage, enhanced stress and cold endurance, and extended longevity. These phenotypic changes are often associated with dynamic alterations in the transcriptome and epigenome. In our previous study, we identified significantly lower H3K27me2 levels in the fat body (FB) of diapausing Culex pipiens. However, the specific roles of the repressive H3K27 methylation marks in mosquito diapause have not been investigated. In the present study, we employed the effective histone lysine demethylase inhibitor GSK-J4 to assess the functions of H3K27me3 levels in the fat body on diapause initiation and phenotypes in Cx. pipiens. Results from solid-state NMR (ssNMR), Fourier-transform infrared spectroscopy (FTIR), and biochemical assays suggest that elevated H3K27me3 levels via GSK-J4 inhibition led to disrupted accumulation of lipids and glycogen in diapausing mosquitoes. GSK-J4 treatment also increased the mortality rate, resulting in lower survivability in treated mosquitoes. Together, these findings propose a crucial role for H3K27me3 in diapause formation, particularly related to energy metabolism. Our results provide a potential target for novel vector control strategies for this species.

Octreotide acetate, the active pharmaceutical ingredient in the long-acting release (LAR) drug product Sandostatin((R)), is a cyclic octapeptide that mimics the naturally occurring somatostatin peptide hormone. Modern NMR can be a robust analytical method to identify and quantify octreotide molecules. Previous H-1 chemical shift assignments were mostly performed in organic solvents, and no assignments for heteronuclear C-13, N-15, and aromatic H-1 nuclei are available. Here, using state-of-the-art 1D and 2D homo- and heteronuclear NMR experiments, octreotide was fully assigned, including water exchangeable amide protons, in aqueous buffer except for (CO)-C-13 and (NH)-N-15 of F1, (NH)-N-15 of C2, and N-15 zeta H zeta of K5 that were not observed because of water exchange or conformational exchange. The solution NMR spectra were then directly compared with 1D H-1/C-13/N-15 solid-state NMR (SSNMR) spectra showing the potential applicability of C-13/N-15 SSNMR for octreotide drug product characterization.

Metal-organic frameworks (MOFs) are renowned for their tunable structure, porosity, and internal chemistry, with demonstrated applications in molecular separations, storage, and conversion. While they are widely usable, the powdery characteristics of MOF materials can be limiting for large-scale processing and implementation in devices. Incorporating MOF particles into polymer supports affords engineering solutions to overcome these issues, yet the nature of the resulting composites is difficult to assess. In this work, we present spectroscopic and calorimetric methods that we believe help establish a holistic physicochemical picture of the composite structure using a series of Zr MOFs with different pore sizes as a testbed. Power law decays are observed in X-ray scattering profiles in low q-space ranging between 2.4 and 3.3, which we interpret as changes in scattering due to polymer infiltrating MOF particles. This interpretation is supported by solid-state nuclear magnetic resonance spectroscopy and differential scanning calorimetry measurements that identify populations of the MOF-associated polymer. Additionally, positron annihilation lifetime spectroscopy measurements collected on a series of composites with different MOF-polymer ratios show multiple decay constants, each correlated to a different free volume elements. In combination with the spectroscopic, calorimetric, and scattering results, we utilize the trends in decay constants as a function of polymer mass fraction to hypothesize a polymer infiltration mechanism whereby large pores are preferentially filled, followed by small pores and, later still, interstitial spaces between particles. Even with vigorous investigation of polymer, MOF, and interface characteristics, the complex and heterogeneous nature of the composites makes absolute structural assertions difficult. We envision that the approaches demonstrated here will be a useful foundation to assess and ultimately guide the design of future MOF-polymer composites.

The polyunsaturated fatty acids docosahexaenoic acid (DHA; 22:6n-3), docosapentaenoic acid (n-3DPA; 22:5n-3), and eicosapentaenoic acid (EPA; 20:5n-3) contain nearly identical structural moieties, but differ vastly in their biological activities and in their utilization in mammalian tissues. Most importantly, DHA cannot be substituted for in fast signal processing tissues such as neural retinal, cardiac and spermatogenic. Over 600 million years of evolution the difference of just a single double bond has not been overcome-DHA reigns supreme. These dramatic differences among polyunsaturated fatty acids are at least in part conformational. Binary 3:1 mixtures of DHA with either alpha-linolenic acid (18:3n-3; ALA) or gamma linolenic acid (18:3n-6; c-LN) and both Nuclear Magnetic Resonance and Gradient Temperature Raman Spectroscopy were utilized to probe DHA in the liquid state. Raman modes at 1970, 1778 and 1578 cm(-1) definitively demonstrate DHA, since absent in c-LN and ALA. However, the latter two modes are also absent in 3:1 mixtures. This is evidence for a conformational change in DHA and of the capacity of structural analogs to disrupt the packing of DHA at the molecular level. NMR confirms chemical shifts in the middle of the DHA double bond region in the mixtures are not the same as the pure DHA chemical shifts.We propose asymmetry in torsion among =C-C-Ha, =C-C-Hb, Ha-C-C= and Hb-C-C= sites in each six carbon atom backbone moiety in =C''-C-C=C-C-C'= results in the observed non-uniformity of twisting observed spectroscopically. The distance C''-C' is minimum when the six atom moiety is fully planar, and maximum when twisting involving C'' and C' is in opposite directions from the double bond. For DHA -(H-C=C-H)-CH2- and -CH2-(H-C=C-H)-peaks are conformationally identical only at C17=C16: C19'' and C14' both twist C'' and C' to the same side of C17=C16. At C14=C13 and C8=C7, torsion is similar to that at C16=C15 in ALA. Torsion related to C''-C' distances stepwise from C2 to C22 results in planar structure more "O " shaped then "U " shaped. In 3 + 1 mixtures, c-LN predominantly disrupts peaks at the C' half of DHA; ALA alters the conformation of the C'' half of DHA. Published by Elsevier B.V.

Aryl diazonium reactions are widely used to covalently modify graphitic electrodes and low-dimensional carbon materials, including the recent creation of organic color centers (OCCs) on single-wall carbon nanotube semiconductors. However, due to the experimental difficulties in resolving small functional groups over extensive carbon lattices, a basic question until now remains unanswered: what group, if any, is pairing with the aryl sp3 defect when breaking a C═C bond on the sp2 carbon lattice? Here, we show that water plays an unexpected role in completing the diazonium reaction with carbon nanotubes involving chlorosulfonic acid, acting as a nucleophilic agent that contributes -OH as the pairing group. By simply replacing water with other nucleophilic solvents, we find it is possible to create OCCs that feature an entirely new series of pairing groups, including -OCH3, -OC2H5, -OC3H7, -i-OC3H7, and -NH2, which allows us to systematically tailor the defect pairs and the optical properties of the resulting color centers. Enabled by these pairing groups, we further achieved the synthesis of OCCs with sterically bulky pairs that exhibit high purity defect photoluminescence effectively covering both the second near-infrared window and the telecom wavelengths. Our studies further suggest that these diazonium reactions proceed through the formation of carbocations in chlorosulfonic acid, rather than a radical mechanism that typically occurs in aqueous solutions. These findings uncover the unknown half of the sp3 defect pairs and provide a synthetic approach to control these defect color centers for quantum information, imaging, and sensing.

Although it is well-established that irradiation of produce can reduce food-borne pathogens and spoilage organisms, data on the effect of irradiation on polymer additives in food packaging materials are limited, particularly for those additives used in packaging leafy greens or in current food packaging materials. We investigated the effects of irradiating a nucleating agent, aluminium, hydroxybis[2,4,8,10-tetrakis(1,1-dimethylethyl)-6-hydroxy-12H-dibenzo [d,g][1,3,2]dioxaphosphocin 6-oxidato]- (CAS Reg. No. 151841-65-5), at doses of 1-20 kGy in polypropylene. That nucleating agent was then extracted using accelerated solvent extraction and analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), liquid chromatography-photodiode array detection (LC-PDA), and solid-state nuclear magnetic resonance (SSNMR) spectroscopy. We found this nucleating agent was not significantly affected by radiation treatment up to 20 kGy. Therefore, this nucleating agent could potentially be useful in food packaging materials that will be irradiated at doses of 20 kGy or less. Establishing which additives are stable under anticipated irradiation doses will help support safety evaluation of food packaging materials.

A polycrystalline iridate Li8IrO6 material was prepared via heating Li2O and IrO2 starting materials in a sealed quartz tube at 650 °C for 48 h. The structure was determined from Rietveld refinement of room-temperature powder neutron diffraction data. Li8IrO6 adopts the nonpolar space group R3̅ with Li atoms occupying the tetrahedral and octahedral sites, which is supported by the electron diffraction and solid-state 7Li NMR. This results in a crystal structure consisting of LiO4 tetrahedral layers alternating with mixed IrO6 and LiO6 octahedral layers along the crystallographic c-axis. The +4 oxidation state of Ir4+ was confirmed by near-edge X-ray absorption spectroscopy. An in situ synchrotron X-ray diffraction study of Li8IrO6 indicates that the sample is stable up to 1000 °C and exhibits no structural transitions. Magnetic measurements suggest long-range antiferromagnetic ordering with a Néel temperature (TN) of 4 K, which is corroborated by heat capacity measurements. The localized effective moment μeff (Ir) = 1.73 μB and insulating character indicate that Li8IrO6 is a correlated insulator. First-principles calculations support the nonpolar crystal structure and reveal the insulating behavior both in paramagnetic and antiferromagnetic states.

Numerous health benefits of seafoods are attributed to their n−3 long-chain polyunsaturated fatty acid content, especially eicosapentaenoic acid (EPA; 20:5n−3) and docosahexaenoic acid (DHA; 22:6n−3). EPA, DHA and their precursor α-linolenic acid (ALA; 18:3n−3) differ vastly biochemically, but from a physical chemical standpoint are close structural analogs. There remains, for example, no satisfactory explanation why only DHA can be utilized in fast signal processing tissues such as neuronal, retinal and cardiac. Recently, gradient temperature Raman spectroscopy has identified key lipid structural differences that require further NMR elucidation. 1H and 13C 1D experiments were performed on neat EPA, DHA, and ALA and 4 different 2D experiments on EPA. The methine 13C spectra show six chemical shifts for ALA; 10 for an EPA, and 12 for DHA. The chemical shift of the first C closest to the C1 carbonyl site is always the most upfield; that of the last C closest to the methyl end is always the most downfield. 1H chemical shift of almost none of the methine protons match. The 13C paired molecular sites identified as conformationally redundant are not identical to the 1H molecular sites identified as conformationally paired. For EPA, long-range coupling is stronger and extends longer at the methyl-ended C18 to C10H2 section and is shorter at C5 to C7H2; also C18 and C17 coupling differ. Repeating (HCCH)CH2 moieties are planar; unequal torsion alters both curvature and twist both ends of the lipids. The methyl end is the most elastic. Asymmetry in twist between the two ends results in torque at the methylene site near the geometric center, resulting in unusually strong electron 13C and 1H shielding.

Culex pipiens is a major carrier of the West Nile Virus, the leading cause of mosquito-borne disease in the continental United States. Cx. pipiens survive overwinter through diapause which is an important survival strategy that is under the control of insulin signaling and Foxo by regulating energy metabolism. Three homologous candidate genes, glycogen synthase ( glys ), atp-binding cassette transporter ( atp ) , and low-density lipoprotein receptor chaperone ( ldlr ), that are under the regulation of Foxo transcription factor were identified in Cx. pipiens . To validate the gene functions, each candidate gene was silenced by injecting the target dsi-RNA to female Cx. pipiens during the early phase of diapause. The dsi-RNA injected diapause-destined female post-adult eclosion were fed for 7 days with 10% glucose containing 1% d -[ 13 C 6 ]glucose. The effects of dsi-RNA knockdown on glucose metabolism in intact mosquitoes were monitored using 13 C solid-state NMR and ATR-FTIR. Our finding shows that the dsi-RNA knockdown of all three candidate genes suppressed glycogen and lipid biosyntheses resulting in inhibition of long-term carbon energy storage in diapausing females.

Hollow multishelled structures (HoMSs) enable material intriguing properties and diverse applications. However, constructing all-polymer HoMSs (p-HoMSs) remains a great challenge. Here, we first develop a one-step self-template strategy to synthesize p-HoMS spheres through controlled reaction-diffusion of a polyelectrolyte pair. Besides instant reaction, the high concentration and moderate molecular weight of one polyelectrolyte as the self-template are required to fulfill the key conditions (i.e., high cross-linking density and high diffusion difference of the two reactants) for the p-HoMS sphere fabrication. In consequence, scalable p-HoMSs are rationally designed with structural and composition control, including shell number, core size, and morphology. More importantly, this p-HoMS could facilely template the synthesis of hierarchical macroscopic HoMS metal oxide with a shell number up to 12. This self-template strategy provides a simple, general, controllable, and large-scale way for the fabrication of HoMS materials with various compositions, complex structures, and diverse functions, signifying for a new methodology in material science.

• C14H2 -(H–C13 = C12–H)– C11H2 -(H–C10 = C9–H)– C8H2 is exactly the same structure in both Linolenic Acid isomers. • In γ-LN, chemical shifts for sites C14H2 and C8H2 are the same (1H = 2.65 ppm; 13C = 24.9 ppm). • In α-LN, 1H chemical shifts for sites C14H2 and C8H2 are the same (2.65 ppm) whereas the 13C chemical shifts are discretely different (24.9 ppm versus 24.7 ppm). • Chemical shifts for C11H2 are similar and unequal (1H = 0.78 ppm, 13C = 13.3 ppm α-LN; 1H = 0.72 ppm 13C = 13.5 ppm γ-LN). • Chemical shifts for C2H2 are similar and unequal (1H = 2.12 ppm, 13C = 33.4 ppm α-LN; 1H = 2.11 ppm 13C = 33.2 ppm γ-LN). • Moiety C17H2-(H–C16 = C15–H) is molecular site among redundant structures in α-LN at which spectroscopic differences are the most different and most important.

Polychlorinated biphenyls are a class of persistent environmental contaminants, and micellar solubilization can be applied to remediate them. The intermolecular aggregates of biphenyl (BP) analogs and cetyltrimethyl ammonium bromide (CTAB) were studied by chemical shift perturbation, nuclear magnetic resonance (NMR) diffusometry, quantitative proton NMR, and nuclear Overhauser effect (NOE) spectroscopy to understand the structural determinants of their solubilization. The micelles of CTAB solubilized BPs readily, but its capacity depended strongly on the nature of the functional group (BPCH2OH > > BPCHO > BPCOOH approximate to BPCl approximate to BP). Upon internalization, the BPs diffused much slower, introduced significant low-frequency H-1 chemical shift changes for CTAB, and displayed strong intermolecular NOEs. The semiquantitative analysis of NOEs revealed further that the BPs are located in the palisade layer closer to the N+(CH3)(3) head group, away from the hydrophobic core. H-1 NMR offers a simple high-throughput screening assay for evaluating and quantitating the solubilization of organics in micelles. The intermolecular NOEs and site-specific perturbation of chemical shifts add further insights on the location of solubilizates in micelles, which may be important for designing surfactants specific for environmental pollutants.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Purpose: To establish regional T1 and T2 values of the healthy mouse brain at ultra‐high magnetic field strength of 17.6 T and to follow regional brain T1 and T2 changes with age.