Making Sense of Disorder in Molecular Solids Using Solid-State NMR

Crystalline materials are typically characterised by diffraction-based techniques which excel at solving the structures of well-ordered materials. However, these techniques have difficulty characterising disorder, as it disrupts the long-range order needed for defined Bragg peaks. Solid-state nuclear magnetic resonance (NMR) is an excellent tool for studying disorder, as it is sensitive to local environment and can detect motion over many orders of magnitude. In this work, NMR-based techniques, primarily lineshape and relaxation analyses, are used in combination with diffraction and molecular dynamics (MD) simulations to uncover the dynamic disorder in three types of system. Firstly, despite limited amounts of some samples, NMR is able to characterise the dynamics of diamondoids, a series of rigid hydrocarbon cages. In diamantane and 1(2)3 tetramantane, 13C relaxation shows evidence of C3 rotations with activation energies of 21.1(4) kJ mol−1 and 15(2) kJ mol−1 respectively. For triamantane, second moments, a historical method of summarising static 1H lineshapes, show that the molecules undergo multi-axis jumps, information that could not be obtained through modern NMR or diffraction-based techniques. Secondly, the phase transition in the relaxor ferroelectric material, hydrazinium magnesium formate, is shown to be caused by reorientation of hydrazinium ions from perpendicular to parallel in the channels. Here, a new mechanism is proposed whereby the relaxor ferroelectric response arises directly because of the molecular motion, not despite it. Finally, MD simulations reveal that the dynamics of the solvent molecules in two cocrystal solvates of furosemide-picolinamide have significant librational character. This explains why lineshape and relaxation analyses, which assume a constant amplitude with temperature, are unable to provide a coherent dynamic model. In summary, the NMR techniques used herein, along with supporting diffraction and computational tools, supports their utilisation in the future to better understand disordered materials

Revisiting the Van Vleck second moment for characterizing molecular motion in organic solids

Van Vleck’s classic theory of the second moment of lineshapes in 1H nuclear magnetic resonance (NMR) is reworked in a form that allows the effect of rapid molecular motion on second moments to be calculated in a semi-analytical fashion. This is much more efficient than existing approaches and also extends previous analyses of (non-dynamic) dipolar networks in terms of site-specific root-sum-square dipolar couplings. The non-local nature of the second moment means that it can discriminate between overall motions that are difficult to discriminate using alternative approaches, such as measurements of NMR relaxation. The value of reviving second moment studies is illustrated on the plastic solids diamantane and triamantane. In the case of triamantane, straightforward measurements of 1H lineshapes on milligram samples show that the molecules in the higher temperature phase undergo multi-axis jumps, information that is not accessible either to diffraction studies or to alternative NMR approaches. The efficiency of the computational methods means that the second moments can be calculated using a readily extensible and open-source Python code

Experimental and numerical study of the cold crucible melting process

The cold crucible, or induction skull melting process as is otherwise known, has the potential to produce high purity melts of a range of difficult to melt materials, including Ti–Al and Ti6Al4V alloys for Aerospace, Ti–Ta and other biocompatible materials for surgical implants, silicon for photovoltaic and electronic applications, etc. A water cooled AC coil surrounds the crucible causing induction currents to melt the alloy and partially suspend it against gravity away from water-cooled surfaces. Strong stirring takes place in the melt due to the induced electromagnetic Lorentz forces and very high temperatures are attainable under the right conditions (i.e., provided contact with water cooled walls is minimised). In a joint numerical and experimental research programme, various aspects of the design and operation of this process are investigated to increase our understanding of the physical mechanisms involved and to maximise process efficiency. A combination of FV and Spectral CFD techniques are used at Greenwich to tackle this problem numerically, with the experimental work taking place at Birmingham University. Results of this study, presented here, highlight the influence of turbulence and free surface behaviour on attained superheat and also discuss coil design variations and dual frequency options that may lead to winning crucible designs

teigen: An R Package for Model-Based Clustering and Classification via the Multivariate t Distribution

The teigen R package is introduced and utilized for model-based clustering and classification. The tEIGEN family of mixtures of multivariate t distributions is formed via an eigen-decomposition of the component covariance matrices and subsequent componentwise constraints. The teigen package implements all previously published tEIGEN family members as well as eight additional models: four multivariate and four univariate. The resulting family of 32 mixture models is implemented in both serial and parallel, with useful dedicated functions. Methodology and examples that illustrate teigen's functionality are presented

Use of distributed generation to control reactive power at the transmission distribution interface

There is an increasing interest in obtaining reactive power services for the transmission system from distributed energy resources. This involves coordination between the transmission and distribution companies, and the distributed generators. This paper presents a methodology to quantify the extent of reactive power provided by distributed generators to the reactive power seen at the transmission and distribution interface. Two case studies using computer load flow simulations are presented based on a real-world network. Results showed that when the distributed generators connected to the distribution network absorb reactive power there will be a multiplier of around 110 % in the reactive power drawn from the transmission system. Similarly, if the distributed generators export reactive power the multiplier is around 90%. This study shows that there is a potential for providing reactive power support from distribution networks to the transmission system at the expense of additional active power losses in the distribution system

The ethics of fertility treatment for same-sex male couples:Considerations for a modern fertility clinic

Social and legal equality for same-sex male couples continues to grow in many countries. Consequently, increasing numbers of same-sex male couples are seeking assisted reproductive technology to achieve parenthood. Fertility treatment for same-sex male couples is an undoubtedly complex issue and raises a variety of ethical concerns. Relevant considerations include ethical issues relating to the surrogate and a possible egg donor, the commissioning same-sex couple, the welfare of the child and the fertility clinic itself. This work analyses these arguments in the context of modern fertility services, providing reflection on the evidence present and what it means for clinicians today. Herein, we argue that fertility treatment for same-sex male couples via surrogacy agreements are acceptable, subject to considerations of each individual case, as in all assisted reproductive treatment. It is in the interest of open and equal access to health services that barriers to assisted reproductive technology for same-sex male couples should be minimised where possible.</p

Effects of a modified muscle sparing posterior technique in hip hemiarthroplasty for displaced intracapsular fractures on postoperative function compared to a standard lateral approach (HemiSPAIRE): protocol for a randomised controlled trial

This is the final version. Available on open access from BMJ publishing via the DOI in this recordIntroduction Currently National Institute for Health and Care Excellence clinical guidelines in the UK suggest that surgeons performing partial hip replacements (hemiarthroplasty) should consider using the lateral approach. Alternatively, a newer, modified posterior approach using a muscle sparing technique named ‘Save Piriformis and Internus, Repairing Externus’ (SPAIRE) can be used leaving the major muscles intact. This randomised controlled trial (RCT) aims to compare the SPAIRE approach to the standard lateral approach, to determine if it allows patients to mobilise better and experience improved function after surgery. Methods and analysis HemiSPAIRE is a two-arm, assessor-blinded, definitive pragmatic RCT with nested pilot and qualitative studies. Two hundred and twenty-eight participants with displaced intracapsular fractures requiring hip hemiarthroplasty will be individually randomised 1:1 to either the SPAIRE, or control (standard lateral approach) surgical procedure. Outcomes will be assessed at postoperative day 3 (POD3) and 120 (POD120). The primary outcome measure will be level of function and mobility using the Oxford Hip Score at POD120. Secondary outcomes include: De Morton Mobility Index (DEMMI), Cumulated Ambulatory Score and Numeric Pain Rating Scale (NPRS) at POD3; DEMMI, NPRS and EQ-5D-5L at POD120, complications, acute and total length of hospital stay, and mortality. Primary analysis will be on an intention-to-treat basis. Participant experiences of the impact of surgery and recovery period will be examined via up to 20 semi-structured telephone interviews. Ethics and dissemination The protocol has been approved by Yorkshire and the Humber—Bradford Leeds Research Ethics Committee. Recruitment commenced in November 2019. Findings will be disseminated via research articles in peer-reviewed journals, presentations at conferences, public involvement events, patient groups and media releases. A summary of the trial findings will be shared with participants at the end of the study. Trial registration number NCT04095611.National Institute for Health Research (NIHR

A multisite longitudinal evaluation of patient characteristics associated with a poor response to non-surgical multidisciplinary management of low back pain in an advanced practice physiotherapist-led tertiary service

Background: Non-surgical multidisciplinary management is often the first pathway of care for patients with chronic low back pain (LBP). This study explores if patient characteristics recorded at the initial service examination have an association with a poor response to this pathway of care in an advanced practice physiotherapist-led tertiary service. Methods: Two hundred and forty nine patients undergoing non-surgical multidisciplinary management for their LBP across 8 tertiary public hospitals in Queensland, Australia participated in this prospective longitudinal study. Generalised linear models (logistic family) examined the relationship between patient characteristics and a poor response at 6 months follow-up using a Global Rating of Change measure. Results: Overall 79 of the 178 (44%) patients completing the Global Rating of Change measure (28.5% loss to follow-up) reported a poor outcome. Patient characteristics retained in the final model associated with a poor response included lower Formal Education Level (ie did not complete school) (Odds Ratio (OR (95% confidence interval)) (2.67 (1.17–6.09), p = 0.02) and higher self-reported back disability (measured with the Oswestry Disability Index) (OR 1.33 (1.01–1.77) per 10/100 point score increase, p = 0.046). Conclusions: A low level of formal education and high level of self-reported back disability may be associated with a poor response to non-surgical multidisciplinary management of LBP in tertiary care. Patients with these characteristics may need greater assistance with regard to their comprehension of health information, and judicious monitoring of their response to facilitate timely alternative care if no benefits are attained.</p

Oxidative stability and changes in the particle size of liposomes used in the Artemia enrichment

The oxidative stability and the particle size of several types of liposomes were assessed in order to characterize their behaviour when submitted to the aggressive conditions of the Artemia enrichments. Results show that all liposomes tested in this study were much more oxidatively stable than a commercial product based on fish oil emulsion. Whereas the initial thiobarbituric acid reactive substances (TBARS) concentration in the emulsion was only slightly higher than in liposomes, the concentration of TBARS in the emulsion increased up to values three orders of magnitude above those registered by liposomes after 21 h of incubation. Among the different liposome formulations, results indicate that vesicles composed of phospholipids containing long-chain highly unsaturated fatty acids (krill phospholipid extract) were generally less stable than those composed of shorter length-chain and more saturated acyl chains. In regards to the particle size changes during enrichment, all liposomes maintained their original size during the experimental period when incubated without nauplii. In the presence of nauplii, liposomes did not exhibit notable changes in their size, except for unilamellar vesicles prepared by the extrusion methodology and formulated with soybean phosphatidylcholine. The implications of the results on the capability of liposomes to be used in Artemia nauplii enrichments are discussed