Non-uniform Photoinduced Unfolding of Supramolecular Polymers Leading to Topological Block Nanofibers

Synthesis of one-dimensional nanofibers with distinct topological (higher-order structural) domains in the same main chain is one of the challenging topics in modern supramolecular polymer chemistry. Non-uniform structural transformation of supramolecular polymer chains by external stimuli may enable preparation of such nanofibers. To demonstrate feasibility of this post-polymerization strategy, we prepared a photoresponsive helically folded supramolecular polymers from a barbiturate monomer containing an azobenzene-embedded rigid π-conjugated scaffold. In contrast to previous helically folded supramolecular polymers composed of a more flexible azobenzene monomer, UV-light induced unfolding of the newly prepared helically folded supramolecular polymers occurred nonuniformly, affording topological block copolymers consisting of folded and unfolded domains. The formation of such blocky copolymers indicates that the photoinduced unfolding of the helically folded structures initiates from relatively flexible parts such as termini or defects. Spontaneous refolding of the unfolded domains was observed after visible-light irradiation followed by aging to restore fully folded structures

Directed assembly of optoelectronically active alkyl-<i>π</i>-conjugated molecules by adding <i>n</i>-alkanes or <i>π</i>-conjugated species

Supramolecular assembly can yield ordered structures by taking advantage of the cumulative effect of multiple non-covalent interactions between adjacent molecules. The thermodynamic origin of many self-assembled structures in water is the balance between the hydrophilic and hydrophobic segments of the molecule. Here, we show that this approach can be generalized to use solvophobic and solvophilic segments of fully hydrophobic alkylated fullerene molecules. Addition of n-alkanes results in their assembly--due to the antipathy of C60 towards n-alkanes--into micelles and hexagonally packed gel-fibres containing insulated C60 nanowires. The addition of pristine C60 instead directs the assembly into lamellar mesophases by increasing the proportion of π-conjugated material in the mixture. The assembled structures contain a large fraction of optoelectronically active material and exhibit comparably high photoconductivities. This method is shown to be applicable to several alkyl-π-conjugated molecules, and can be used to construct organized functional materials with π-conjugated sections

Predictors of the experience of a Cytosponge test: analysis of patient survey data from the BEST3 trial

Availability of data and materials: The trial protocol, statistical analysis plan, and statistical report are available via the University of Cambridge data repository (https://www.data.cam.ac.uk/repository). Datasets will be available from R Fitzgerald ([email protected]) on request.Copyright © The Author(s) 2023. Background: The Cytosponge is a cell-collection device, which, coupled with a test for trefoil factor 3 (TFF3), can be used to diagnose Barrett’s oesophagus, a precursor condition to oesophageal adenocarcinoma. BEST3, a large pragmatic, randomised, controlled trial, investigated whether offering the Cytosponge-TFF3 test would increase detection of Barrett’s. Overall, participants reported mostly positive experiences. This study reports the factors associated with the least positive experience. Methods: Patient experience was assessed using the Inventory to Assess Patient Satisfaction (IAPS), a 22-item questionnaire, completed 7–14 days after the Cytosponge test. Study cohort: All BEST3 participants who answered ≥ 15 items of the IAPS (N = 1458). Statistical analysis: A mean IAPS score between 1 and 5 (5 indicates most negative experience) was calculated for each individual. ‘Least positive’ experience was defined according to the 90th percentile. 167 (11.4%) individuals with a mean IAPS score of ≥ 2.32 were included in the ‘least positive’ category and compared with the rest of the cohort. Eleven patient characteristics and one procedure-specific factor were assessed as potential predictors of the least positive experience. Multivariable logistic regression analysis using backwards selection was conducted to identify factors independently associated with the least positive experience and with failed swallow at first attempt, one of the strongest predictors of least positive experience. Results: The majority of responders had a positive experience, with an overall median IAPS score of 1.7 (IQR 1.5–2.1). High (OR = 3.01, 95% CI 2.03–4.46, p < 0.001) or very high (OR = 4.56, 95% CI 2.71–7.66, p < 0.001) anxiety (relative to low/normal anxiety) and a failed swallow at the first attempt (OR = 3.37, 95% CI 2.14–5.30, p < 0.001) were highly significant predictors of the least positive patient experience in multivariable analyses. Additionally, sex (p = 0.036), height (p = 0.032), alcohol intake (p = 0.011) and education level (p = 0.036) were identified as statistically significant predictors. Conclusion: We have identified factors which predict patient experience. Identifying anxiety ahead of the procedure and discussing particular concerns with patients or giving them tips to help with swallowing the capsule might help improve their experience. Trial registration ISRCTN68382401.The BEST3 trial was funded by Cancer Research UK (C14478/A21047), National Institute for Health Research covering service support costs, the UK National Health Service funding excess treatment costs and Medtronic providing funding for Cytosponge devices and TFF3 antibodies. RCF is funded by a Programme Grant from the Medical Research Council (RG84369) and is CI for the BEST3 trial and the Innovate UK funded DELTA study. JO was supported by PDS’s Cancer Research UK programme Grant (C8162/A16892) and is currently supported by the Barts Charity (EMSG1K1R). RM was supported by PDS’ Cancer Research UK Cancer Prevention Clinical Trials Unit funding (Grant No.: C8162/A25356). SGS is supported by a Yorkshire Cancer Research Fellowship. JW is funded by a Cancer Research UK career development fellowship (C7492/A17219). BG was funded as part of the DELTA study by Innovate UK (Grant No. 41162). FW is supported by the Cancer Research UK CanTest Grant [C8640/A23385]. RL is supported by the Intramural Research Program of the US National Institutes of Health/National Cancer Institute

Genomic epidemiology of SARS-CoV-2 in a UK university identifies dynamics of transmission

AbstractUnderstanding SARS-CoV-2 transmission in higher education settings is important to limit spread between students, and into at-risk populations. In this study, we sequenced 482 SARS-CoV-2 isolates from the University of Cambridge from 5 October to 6 December 2020. We perform a detailed phylogenetic comparison with 972 isolates from the surrounding community, complemented with epidemiological and contact tracing data, to determine transmission dynamics. We observe limited viral introductions into the university; the majority of student cases were linked to a single genetic cluster, likely following social gatherings at a venue outside the university. We identify considerable onward transmission associated with student accommodation and courses; this was effectively contained using local infection control measures and following a national lockdown. Transmission clusters were largely segregated within the university or the community. Our study highlights key determinants of SARS-CoV-2 transmission and effective interventions in a higher education setting that will inform public health policy during pandemics.</jats:p

Nutrient uptake and distribution by bread and durum wheat under drought conditions in South Australia

An important limitation to the production of durum wheat in South Australia is its poor adaptation to the alkaline, sodic soils of the cereal belt, which often results in nutrient imbalances in the crop. A field experiment was conducted at Palmer, South Australia, to measure the nutrient uptake and distribution between grain and straw of 3 bread wheat cultivars and 9 cultivars and breeding lines of durum wheat. The purpose of the work was to characterise the patterns of nutrient uptake and to examine whether there were major, consistent differences between bread wheat and durum wheat. Rainfall during the growing season was below average and the crops suffered from drought stress after anthesis. Plants were marginally deficient or deficient in nitrogen (N), phosphorus (P) and zinc (Zn), and boron (B) concentrations were high. Compared with bread wheat, durum wheat had a very much higher concentration of sodium (Na), higher concentrations of calcium (Ca) and sulfur (S), but lower concentrations of potassium (K), magnesium (Mg), manganese (Mn) and copper (Cu). Total amounts of P, Zn and Na in the shoot continued to increase throughout the growing season with significant increases occurring during grain filling, whereas there was little increase in the amount of N, K, B and Mn during grain filling. The maximum rate of nutrient uptake occurred before the time of maximum crop growth rate, and was in the order K (10.1 weeks after sowing), N (10.6), P (11.3), Mn (12.0), Zn (12.5) and B (14.6); maximum growth rate occurred at 14.8 weeks. There was no consistent difference between bread and durum wheat in the partitioning of nutrients to the grain. The importance of N and Zn uptake to the growth of the durum wheat genotypes was shown by significant correlations between maximum uptake rates of these nutrients and maximum crop growth rate, with the strongest correlation being with Zn. Growth rate was not correlated with uptake rates of other nutrients. A number of genotypes of durum wheat had maximum rates of Zn and Mn accumulation up to twice those of the current commercial genotypes. Some of these lines have yielded well at Zn- and Mn-deficient sites which indicates that the micronutrient efficiency of durum can be improved. Late in the season the experiment showed signs of infection by crown rot (Fusarium graminearum Schw. Group 1). Durum wheat showed more severe symptoms than bread wheat and the number of white heads in durum wheat was inversely correlated with the concentration of Zn in the shoot during the pre-anthesis period.A. Zubaidi, G. K. McDonald and G. J. Hollamb

Shoot growth, root growth and grain yield of bread and durum wheat in South Australia

In South Australia, durum wheat yields more than bread wheat under well-watered and fertile conditions, but over much of the state’s cereal belt the yields of durum wheat, relative to bread wheat, are low. Three experiments were conducted over 3 years at 2 sites to compare the growth and yield of bread and durum wheat and to investigate some of the reasons for the differences in the relative yields of the 2 cereals. Durum wheat yielded less than bread wheat when annual rainfall was less than about 450 mm or when the site mean yield for bread wheat was less than 250 g/m². Compared with bread wheat, durum wheat had poorer early vigour, which was associated with fewer tillers/m², and produced fewer kernels/m². Under favourable grain filling conditions, durum wheat produced larger kernels than bread wheat but its kernel weight was more variable across sites and seasons and consequently, the relative yields of the 2 cereals depended largely on kernel weight. For example, in a wet year, durum wheat yielded 20% more than bread wheat, despite producing 16% fewer kernels/m², because of its larger kernels (52 v. 36 mg). In 2 drier years, kernel weights of durum and bread wheat were similar (durum and bread wheat mean kernel weights: 40 v. 37 mg; 30 v. 33 mg) and so durum was unable to overcome the limitation of fewer kernels/m² and its yields were similar to or less than bread wheat. Root length densities of durum and bread wheat below 30 cm were low. Durum wheat had an equivalent or lower root length density than bread wheat and lower length per gram of root dry matter, indicating less finely divided roots. This suggests that durum wheat may sometimes be less able than bread wheat to utilise moisture and nutrient reserves in the subsoil because of a smaller root system. This is an undesirable characteristic for a crop that appears to be more reliant than bread wheat on producing large kernels for high yields. Efforts to improve the yield of durum wheat, either through genetic improvement or by agronomic means, should focus on reducing the levels of stress during the post anthesis period so that limitations to kernel growth are minimised. Improving the early vigour of the crop, having cultivars of the appropriate maturity and with adequate levels of resistance to root disease, and improving root growth and function in the subsoil are likely to be desirable characteristics.A. Zubaidi, G. K. McDonald and G. J. Hollamb

Genetic and environmental variation for grain quality traits routinely evaluated in southern Australian wheat breeding programs

Milling yield, maximum dough resistance (Rmax), dough extensibility, flour protein concentration (flour protein), particle size index (PSI), water absorption, and dough development time are important determinants of grain quality and are routinely evaluated in Australian wheat breeding programs. Information on allelic variation at the 6 loci determining glutenin proteins is also regularly obtained and used to predict Rmax and extensibility. For each character, except dough development time, 4029 observations on 2377 lines and 94 environments were analysed to estimate genotypic and environmental variances, heritabilities, genotypic and environmental correlations, and the effects of glutenin genes. A subset was analysed for dough development time. Milling yield, Rmax, extensibility, PSI, water absorption, and dough development time had intra-class correlation coefficients, or broad-sense heritabilities, between 0.66 and 0.76, and extensibility had a value of 0.52, with flour protein at 0.36. Genotypic and environmental correlations between extensibility and flour protein were high at +0.78 and +0.85, respectively. Rmax had a genotypic correlation with dough development time of +0.67, which was substantially due to pleiotropic effects of glutenin genes. Rmax, extensibility, PSI, and dough development time were influenced by glutenin genes. For Rmax about 50% of the genotypic variance could be explained by glutenin genes. For extensibility about 50% could be explained by flour protein, with 50% of the remainder by the inclusion of glutenin genes. For dough development time about 15% could be explained by flour protein, with a further 30% by glutenin genes. For PSI, about 40% of the genotypic variation could be accounted for by glutenin genes after the removal of the effects of flour protein and milling yield. We concluded that dough development time could be added to Rmax and extensibility as a trait that can be usefully predicted by the glutenin genes, but more work is required for PSI