Investigating Cell Wall Diffusion in Wood Modified with Phenol Urea Formaldehyde Resin in Different Length Scales.

Wood modification using low molecular weight thermosetting resins improves the biological durability and dimensional stability of wood while avoiding increasingly regulated biocides. During the modification process, resin monomers diffuse from the cell lumen to the cell wall, occupying micropore spaces before curing at 150 °C. This study investigated the mechanism of cell wall diffusion at multiple scales, comparing two test groups where diffusion was either facilitated or restricted.

Organic NMR crystallography: enabling progress for applications to pharmaceuticals and plant cell walls.

The application of NMR crystallography to organic molecules is exemplified by two case studies. For the tosylate salt of the active pharmaceutical ingredient, Ritlectinib, solid-state NMR spectra are presented at a H Larmor frequency of 1 GHz and a magic-angle spinning (MAS) frequency of 60 kHz. Specifically, N-H heteronuclear multiple-quantum coherence (HMQC) and H-H double-quantum (DQ) single-quantum (SQ) correlation experiments are powerful probes of hydrogen bonding interactions.

Cervical Spine Manipulation and Causation of Cervical Artery Dissection: A Review of 10 Case Reports.

Recent media coverage of high-profile cases of cervical artery dissection (CAD) has ignited the discussion about the role of cervical spine manipulation (CSM) in causing cervical artery dissection. However, research does not support a causal association between cervical spine manipulation and cervical artery dissection in a healthy cervical spine. The objective of this study was to review the 10 most recent case reports of cervical spine manipulation and cervical artery dissection for convincing evidence of the causation of cervical artery dissection by cervical spine manipulation.

Diagnosis of Cervical Spinal Cord Multiple Sclerosis by a Chiropractic Physician: A Case Report.

We present a case report of diagnosis of cervical spine multiple sclerosis by a chiropractic physician. This unique case contributes an account of a challenging differential diagnosis to the literature. A 30-year-old male presented with a three-year history of diffuse left upper extremity motor strength deficits and paresthesia (numbness and tingling).

Plausible Mechanisms of Causation of Immediate Stroke by Cervical Spine Manipulation: A Narrative Review.

It has been proposed that cervical spine manipulation (CSM) can cause dissection in healthy cervical arteries, with resultant immediate stroke. However, research does not support a causal association between CSM and cervical artery dissection (CAD) in healthy cervical arteries. The objective of this study was to review the literature to identify plausible mechanisms of causation of immediate stroke by CSM.

Polymorph Identification for Flexible Molecules: Linear Regression Analysis of Experimental and Calculated Solution- and Solid-State NMR Data.

The Δδ regression approach of Blade et al. [ 2020, 124(43), 8959-8977] for accurately discriminating between solid forms using a combination of experimental solution- and solid-state NMR data with density functional theory (DFT) calculation is here extended to molecules with multiple conformational degrees of freedom, using furosemide polymorphs as an exemplar. As before, the differences in measured H and C chemical shifts between solution-state NMR and solid-state magic-angle spinning (MAS) NMR (Δδ) are compared to those determined by gauge-including projector augmented wave (GIPAW) calculations (Δδ) by regression analysis and a -test, allowing the correct furosemide polymorph to be precisely identified.

Impacted and Angulated Right Hip Fracture in a Patient Reporting No History of Trauma Presenting to a Chiropractic Physician: A Case Report.

A case involving a patient with an impacted and angulated femoral neck fracture presenting to a chiropractic physician is rare. This unique case contributes an account of a challenging differential diagnosis to the literature. A 65-year-old female, reporting no history of trauma, presented with a two-week history of right lower back and right anterior hip pain radiating down the front of the right thigh in the L2-L4 dermatome.

Nuclear spin diffusion under fast magic-angle spinning in solid-state NMR.

Solid-state nuclear spin diffusion is the coherent and reversible process through which spin order is transferred via dipolar couplings. With the recent increases in magic-angle spinning (MAS) frequencies and magnetic fields becoming routinely applied in solid-state nuclear magnetic resonance, understanding how the increased 1H resolution obtained affects spin diffusion is necessary for interpretation of several common experiments. To investigate the coherent contributions to spin diffusion with fast MAS, we have developed a low-order correlation in Liouville space model based on the work of Dumez et al.

Comparison of methods for N-H recoupling in N-H HMQC MAS NMR.

H-detected N heteronuclear multiple-quantum coherence (HMQC) magic-angle-spinning (MAS) NMR experiments performed at fast magic-angle spinning (≥50 kHz) are finding increasing application, e.g., to pharmaceuticals.

Discovering the Solid-State Secrets of Lorlatinib by NMR Crystallography: To Hydrogen Bond or not to Hydrogen Bond.

Lorlatinib is an active pharmaceutical ingredient (API) used in the treatment of lung cancer. Here, an NMR crystallography analysis is presented whereby the single-crystal X-ray diffraction structure (CSD: 2205098) determination is complemented by multinuclear (H, C, /N, F) magic-angle spinning (MAS) solid-state NMR and gauge-including projector augmented wave (GIPAW) calculation of NMR chemical shifts. Lorlatinib crystallises in the P2 space group, with two distinct molecules in the asymmetric unit cell, Z' = 2.

Elucidation of microbial lignin degradation pathways using synthetic isotope-labelled lignin.

Pathways by which the biopolymer lignin is broken down by soil microbes could be used to engineer new biocatalytic routes from lignin to renewable chemicals, but are currently not fully understood. In order to probe these pathways, we have prepared synthetic lignins containing C at the sidechain β-carbon. Feeding of [β-C]-labelled DHP lignin to RHA1 has led to the incorporation of C label into metabolites oxalic acid, 4-hydroxyphenylacetic acid, and 4-hydroxy-3-methoxyphenylacetic acid, confirming that they are derived from lignin breakdown.

Exploring the Potential of Multinuclear Solid-State H, C, and Cl Magnetic Resonance To Characterize Static and Dynamic Disorder in Pharmaceutical Hydrochlorides.

Crystallographic disorder, whether static or dynamic, can be detrimental to the physical and chemical stability, ease of crystallization and dissolution rate of an active pharmaceutical ingredient. Disorder can result in a loss of manufacturing control leading to batch-to-batch variability and can lengthen the process of structural characterization. The range of NMR active nuclei makes solid-state NMR a unique technique for gaining nucleus-specific information about crystallographic disorder.

Correction: Optimisation of H PMLG homonuclear decoupling at 60 kHz MAS to enable N-H through-bond heteronuclear correlation solid-state NMR spectroscopy.

Correction for 'Optimisation of H PMLG homonuclear decoupling at 60 kHz MAS to enable N-H through-bond heteronuclear correlation solid-state NMR spectroscopy' by Jacqueline Tognetti , , 2022, , 20258-20273, https://doi.org/10.1039/D2CP01041K.

Optimisation of H PMLG homonuclear decoupling at 60 kHz MAS to enable N-H through-bond heteronuclear correlation solid-state NMR spectroscopy.

The Lee-Goldburg condition for homonuclear decoupling in H magic-angle spinning (MAS) solid-state NMR sets the angle , corresponding to arctan of the ratio of the rf nutation frequency, , to the rf offset, to be the magic angle, , equal to tan(√2) = 54.7°. At 60 kHz MAS, we report enhanced decoupling compared to MAS alone in a H spectrum of N-glycine with at = 30° for a of ∼100 kHz at a H Larmor frequency, , of 500 MHz and 1 GHz, corresponding to a high chemical shift scaling factor () of 0.

Combining X-ray and NMR Crystallography to Explore the Crystallographic Disorder in Salbutamol Oxalate.

Salbutamol is an active pharmaceutical ingredient commonly used to treat respiratory distress and is listed by the World Health Organization as an essential medicine. Here, we establish the crystal structure of its oxalate form, salbutamol oxalate, and explore the nature of its crystallographic disorder by combined X-ray crystallography and C cross-polarization (CP) magic-angle spinning (MAS) solid-state NMR. The *C-OH chiral center of salbutamol (note that the crystal structures are a racemic mixture of the two enantiomers of salbutamol) is disordered over two positions, and the -butyl group is rotating rapidly, as revealed by C solid-state NMR.

Eudicot primary cell wall glucomannan is related in synthesis, structure, and function to xyloglucan.

Hemicellulose polysaccharides influence assembly and properties of the plant primary cell wall (PCW), perhaps by interacting with cellulose to affect the deposition and bundling of cellulose fibrils. However, the functional differences between plant cell wall hemicelluloses such as glucomannan, xylan, and xyloglucan (XyG) remain unclear. As the most abundant hemicellulose, XyG is considered important in eudicot PCWs, but plants devoid of XyG show relatively mild phenotypes.

Combining heteronuclear correlation NMR with spin-diffusion to detect relayed Cl-H-H and N-H-H proximities in molecular solids.

Analysis of short-to-intermediate range intermolecular interactions offers a great way of characterizing the solid-state organization of small molecules and materials. This can be achieved by two-dimensional (2D) homo- and heteronuclear correlation NMR spectroscopy, for example, by carrying out experiments at high magnetic fields in conjunction with fast magic-angle spinning (MAS) techniques. But, detecting 2D peaks for heteronuclear dipolar coupled spin pairs separated by greater than 3 Å is not always straightforward, particularly when low-gamma quadrupolar nuclei are involved.

A toolbox for improving the workflow of NMR crystallography.

NMR crystallography is a powerful tool with applications in structural characterization and crystal structure verification, to name two. However, applying this tool presents several challenges, especially for industrial users, in terms of consistency, workflow, time consumption, and the requirement for a high level of understanding of experimental solid-state NMR and GIPAW-DFT calculations. Here, we have developed a series of fully parameterized scripts for use in Materials Studio and TopSpin, based on the .

Importance of Water in Maintaining Softwood Secondary Cell Wall Nanostructure.

Water is one of the principal constituents by mass of living plant cell walls. However, its role and interactions with secondary cell wall polysaccharides and the impact of dehydration and subsequent rehydration on the molecular architecture are still to be elucidated. This work combines multidimensional solid-state C magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) with molecular dynamics modeling to decipher the role of water in the molecular architecture of softwood secondary cell walls.

Synergy of Solid-State NMR, Single-Crystal X-ray Diffraction, and Crystal Structure Prediction Methods: A Case Study of Teriflunomide (TFM).

In this work, for the first time, we present the X-ray diffraction crystal structure and spectral properties of a new, room-temperature polymorph of teriflunomide (TFM), CSD code 1969989. As revealed by DSC, the low-temperature TFM polymorph recently reported by Gunnam et al. undergoes a reversible thermal transition at -40 °C.

Cl- H Heteronuclear correlation magic-angle spinning nuclear magnetic resonance experiments for probing pharmaceutical salts.

Heteronuclear multiple-quantum coherence (HMQC) pulse sequences for establishing heteronuclear correlation in solid-state nuclear magnetic resonance (NMR) between Cl and H nuclei in chloride salts under fast (60 kHz) magic-angle spinning (MAS) and at high magnetic field (a H Larmor frequency of 850 MHz) are investigated. Specifically, recoupling of the Cl- H dipolar interaction using rotary resonance recoupling with phase inversion every rotor period or the symmetry-based SR4 pulse sequences are compared. In our implementation of the population transfer (PT) dipolar (D) HMQC experiment, the satellite transitions of the Cl nuclei are saturated with an off-resonance WURST sweep, at a low nutation frequency, over the second spinning sideband, whereby the WURST pulse must be of the same duration as the recoupling time.