In situ photochemistry on a benchtop NMR spectrometer with pH2 hyperpolarisation

High-resolution benchtop NMR spectrometers are uniquely suited for reaction monitoring applications, owing to their portability and accessibility, but the low inherent sensitivity of the approach can limit the observation of low-concentration transient species. In this work, a hyperpolarisation technique called parahydrogen induced polarisation (PHIP) was employed to overcome this limitation and observe both thermal and photochemical reactivity. The developed PHIP hyperpolarised reaction monitoring procedure enabled quantitative analysis of the oxidative addition of H2 to trans-[IrCl(CO)(PPh3)2], with a k2 rate constant of (0.89 ± 0.03) dm3 mol-1 s-1 showing excellent consistency with established literature. The method was validated against several key experimental parameters (including temperature and relaxation) to establish it as a robust route to accurately monitor reactions at low-field. Through integration of low-cost ex situ and in situ photochemistry setups that utilise broadband UV sources, the photochemistry of metal dihydrides (M = Ir, Ru) was explored on a benchtop NMR spectrometer for the first time. Implementation of a photochemical pump - NMR probe method with the in situ photochemistry setup allowed observation of photochemistry on the micro-to-millisecond timescale enabling the observation of short-lived hyperpolarised cis-[Ru(H)2(dppe)2] (with a hyperpolarised T1 of (250 ± 20) ms). This setup was employed to detect coherent magnetic evolution of metal complexes formed from addition of parahydrogen which has only been observed previously using a laser within a high-field NMR setup. Magnetic evolution was observed for cis-[Ru(H)2(dppe)2], [Ru(H)2(CO)2(dpae)], [Ir(H)2(CO)(PPh3)2I] and [Ir(H)2(13CO)(PPh3)2I] indicating the viability of a low-cost, benchtop NMR alternative to currently established practices

Remarkable transmission of microwaves through a wall of long metallic bricks

Copyright © 2001 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters 79 (2001) and may be found at http://link.aip.org/link/?APPLAB/79/2844/1The transmitted intensity of a microwave beam through a thick continuous metal wall will be effectively zero due to the almost complete exclusion of the electric field from the metal. However, it is shown here that by removing less than 20% of the wall material to produce a regular array of bricks, up to 90% of the radiation is transmitted, despite the gaps between the bricks being less than 5% of the incident wavelength. This result is attributed to the excitation of a set of resonant waves along the cavity length through the coupling together of surface–plasmon modes across its width

Mapping a waste disposal site using Tellus airborne geophysical data

Leakage of fluids from unregulated and/or poorly engineered waste disposal sites poses a significant direct risk to groundwater quality. Characterisation and monitoring of waste disposal sites and potentially associated groundwater contaminant plumes are generally invasive, time-consuming and expensive, particularly when the extent of the plume is unknown. This study examines the value of incorporating of Tellus and Tellus Border airborne electromagnetic (AEM) data into current assessment protocols for the characterisation and monitoring of contaminant sources and subsurface contaminant plumes. The findings demonstrate the feasibility of using airborne and ground-based non-invasive geophysical data as part of existing tiered assessment protocols for prioritising suspected sites and for guiding targeted intrusive investigations and subsequent remediation efforts

Hyperpolarised 1H-13C benchtop NMR spectroscopy

Benchtop NMR spectrometers with sub-ppm spectral resolution have opened up new opportunities for performing NMR outside of the standard laboratory environment. However, the relatively weak magnetic fields of these devices (1 - 2 T) results in low sensitivity and significant peak overlap in 1H NMR spectra. Here we use hyperpolarised 13C{1H} NMR to overcome these challenges. Specifically, we demonstrate the use of the signal amplification by reversible exchange (SABRE) parahydrogen-based hyperpolarisation technique to enhance the sensitivity of natural abundance 1D and 2D 13C{1H} benchtop NMR spectra. We compare two detection methods for SABRE-enhanced 13C NMR and observe an optimal 13C{1H} signal-to-noise ratio (SNR) for a refocused INEPT approach, where hyperpolarisation is transferred from 1H to 13C. In addition, we exemplify SABRE-enhanced 2D 13C benchtop NMR through the acquisition of a 2D HETCOR spectrum of 260 mM of 4-methylpyridine at natural isotopic abundance in a total experiment time of 69 mins. In theory, signal averaging for over 300 days would be required to achieve a comparable SNR for a thermally polarised benchtop NMR spectrum acquired of a sample of the same concentration at natural abundanc

Software Citation Implementation Challenges

The main output of the FORCE11 Software Citation working group (https://www.force11.org/group/software-citation-working-group) was a paper on software citation principles (https://doi.org/10.7717/peerj-cs.86) published in September 2016. This paper laid out a set of six high-level principles for software citation (importance, credit and attribution, unique identification, persistence, accessibility, and specificity) and discussed how they could be used to implement software citation in the scholarly community. In a series of talks and other activities, we have promoted software citation using these increasingly accepted principles. At the time the initial paper was published, we also provided guidance and examples on how to make software citable, though we now realize there are unresolved problems with that guidance. The purpose of this document is to provide an explanation of current issues impacting scholarly attribution of research software, organize updated implementation guidance, and identify where best practices and solutions are still needed

Risk and Protective Factors for the Occurrence of Sporadic Pancreatic Endocrine Neoplasms

Pancreatic neuroendocrine neoplasms (PNENs) represent 10% of all pancreatic tumors by prevalence. Their incidence has reportedly increased over recent decades in parallel with that of pancreatic adenocarcinoma. PNENs are relatively rare, and of the few institutions that have published potential risk factors, findings have been heterogeneous. Our objective was to investigate the association between potential risk and protective factors for the occurrence of sporadic PNENs across a European population from several institutions. A multinational European case-control study was conducted to examine the association of selected environmental, family and medical exposure factors using a standardized questionnaire in face-to-face interviews. A ratio of 1:3 cases to controls were sex and age matched at each study site. Adjusted univariate and multivariate logistic regression analysis were performed for statistically significant factors. The following results were obtained: In 201 cases and 603 controls, non-recent onset diabetes (OR 2.09, CI 1.27-3.46) was associated with an increased occurrence of PNENs. The prevalence of non-recent onset diabetes was higher both in cases with metastatic disease (TNM stage III-IV) or advanced grade (G3) at the time of diagnosis. The use of metformin in combination with insulin was also associated with a more aggressive phenotype. Drinking coffee was more frequent in cases with localized disease at diagnosis. Our study concluded that non-recent onset diabetes was associated with an increased occurrence of PNENs and the combination of metformin and insulin was consistent with a more aggressive PNEN phenotype. In contrast to previous studies, smoking, alcohol and first-degree family history of cancer were not associated with PNEN occurrence

LQTS Gene LOVD Database

The Long QT Syndrome (LQTS) is a group of genetically heterogeneous disorders that predisposes young individuals to ventricular arrhythmias and sudden death. LQTS is mainly caused by mutations in genes encoding subunits of cardiac ion channels (KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2). Many other genes involved in LQTS have been described recently (KCNJ2, AKAP9, ANK2, CACNA1C, SCNA4B, SNTA1, and CAV3). We created an online database (http://www.genomed.org/LOVD/introduction.html) that provides information on variants in LQTS-associated genes. As of February 2010, the database contains 1738 unique variants in 12 genes. A total of 950 variants are considered pathogenic, 265 are possible pathogenic, 131 are unknown/unclassified, and 292 have no known pathogenicity. In addition to these mutations collected from published literature, we also submitted information on gene variants, including one possible novel pathogenic mutation in the KCNH2 splice site found in ten Chinese families with documented arrhythmias. The remote user is able to search the data and is encouraged to submit new mutations into the database. The LQTS database will become a powerful tool for both researchers and clinicians. © 2010 Wiley-Liss, Inc

D-mannose for prevention of recurrent urinary tract infection among women: a randomized clinical trial

Importance Recurrent urinary tract infection (UTI) is a common debilitating condition in women, with limited prophylactic options. d-Mannose has shown promise in trials based in secondary care, but effectiveness in placebo-controlled studies and community settings has not been established. Objective To determine whether d-mannose taken for 6 months reduces the proportion of women with recurrent UTI experiencing a medically attended UTI. Design, Setting, and Participants This 2-group, double-blind randomized placebo-controlled trial took place across 99 primary care centers in the UK. Participants were recruited between March 28, 2019, and January 31, 2020, with 6 months of follow-up. Participants were female, 18 years or older, living in the community, and had evidence in their primary care record of consultations for at least 2 UTIs in the preceding 6 months or 3 UTIs in 12 months. Invitation to participate was made by their primary care center. A total of 7591 participants were approached, 830 responded, and 232 were ineligible or did not proceed to randomization. Statistical analysis was reported in December 2022. Intervention Two grams daily of d-mannose powder or matched volume of placebo powder. Main Outcomes and Measures The primary outcome measure was the proportion of women experiencing at least 1 further episode of clinically suspected UTI for which they contacted ambulatory care within 6 months of study entry. Secondary outcomes included symptom duration, antibiotic use, time to next medically attended UTI, number of suspected UTIs, and UTI-related hospital admissions. Results Of 598 women eligible (mean [range] age, 58 [18-93] years), 303 were randomized to d-mannose (50.7%) and 295 to placebo (49.3%). Primary outcome data were available for 583 participants (97.5%). The proportion contacting ambulatory care with a clinically suspected UTI was 150 of 294 (51.0%) in the d-mannose group and 161 of 289 (55.7%) in the placebo group (risk difference, −5%; 95% CI, −13% to 3%; P = .26). Estimates were similar in per protocol analyses, imputation analyses, and preplanned subgroups. There were no statistically significant differences in any secondary outcome measures. Conclusions and Relevance In this randomized clinical trial, daily d-mannose did not reduce the proportion of women with recurrent UTI in primary care who experienced a subsequent clinically suspected UTI. d-Mannose should not be recommended for prophylaxis in this patient group. Trial Registration isrctn.org Identifier: ISRCTN1328351