Although acute respiratory infections can lead to cardiovascular complications, the effect of underlying cardiovascular risk on the incidence of acute respiratory infections and cardiovascular complications following acute respiratory infection in individuals without established cardiovascular disease is unknown. We aimed to investigate whether cardiovascular risk is associated with increased risk of acute respiratory infection and acute cardiovascular events after acute respiratory infection using 10 years of linked electronic health record (EHR) data in England.In this retrospective, population-based cohort study we used EHRs from primary care providers registered on the Clinical Practice Research Datalink (CPRD) GOLD and Aurum databases in England. Eligible individuals were aged 40–64 years, did not have established cardiovascular disease or a chronic health condition that would make them eligible for influenza vaccination, were registered at a general practice contributing to the CPRD, and had linked Hospital Episode Statistics Admitted Patient Care data in England from Sept 1, 2008, to Aug 31, 2018. We classified cardiovascular risk on the basis of diagnosed hypertension and overall predicted cardiovascular risk, estimated by use of the QRISK2 risk-prediction tool (comparing a score of ≥10% [increased risk] with a score of <10% [low risk]). Using multivariable Poisson regression models, we calculated incidence rate ratios (IRRs) for systemic acute respiratory infection. Among individuals who had an acute respiratory infection, we used multivariable Cox regression to calculate hazard ratios (HRs) for the risk of acute cardiovascular events within 1 year of infection.We identified 6 075 321 individuals aged 40–64 years with data in the CPRD and linked data in the Hospital Episode Statistics Admitted Patient Care database between Sept 1, 2008, and Aug 31, 2018. Of these individuals, 4 212 930 (including 526 480 [12·5%] with hypertension and 607 087 [14·4%] with a QRISK2 score of ≥10%) were included in the assessment of the incidence of acute respiratory infection. After adjusting for confounders , the incidence of acute respiratory infection was higher in individuals with hypertension than those without (IRR 1·04 [95% CI 1·03–1·05]) and higher in those with a QRISK2 score of 10% or higher than in those with a QRISK2 score of less than 10% (1·39 [1·37–1·40]). Of the 442 408 individuals who had an acute respiratory infection, 4196 (0·9%) had an acute cardiovascular event within 1 year of infection. After adjustment , hypertension (HR 1·98 [95% CI 1·83–2·15]) and a QRISK2 score of 10% or higher (3·65 [3·42–3·89]) were associated with a substantially increased risk of acute cardiovascular events after acute respiratory infection.People with increased cardiovascular risk but without diagnosed cardiovascular disease, measured by diagnosed hypertension or overall predicted cardiovascular risk, could benefit from influenza and pneumococcal vaccine prioritisation to reduce their risk of both acute respiratory infection and cardiovascular complications following an acute respiratory infection.British Heart Foundation and the Wellcome Trust. Streptococcus pneumoniae and the influenza virus, are known to trigger cardiovascular events.4The COVID-19 pandemic has expedited research on cardiovascular complications following systemic acute respiratory infection. Before the pandemic, observational studies showed that acute respiratory infections increased the risk of myocardial infarction and stroke. In self-controlled case-series using large electronic health record (EHR) datasets, risk of myocardial infarction and stroke was elevated by 2–6 times in the days following clinically diagnosed acute respiratory infection, with the risk remaining elevated for up to 1 month.Evidence before this studyBefore the COVID-19 pandemic, self-controlled case-series estimated a 2–6 times transient increase in the risk of myocardial infarction and stroke following a range of clinically diagnosed or laboratory-confirmed acute respiratory infections. These studies did not explore whether these effects were modified by underlying cardiovascular risk. We searched PubMed using the search terms “*hypertensi*” OR “cardiovascular risk” AND “influenza” OR “pneumonia” OR “respiratory infection” AND “cardiovascular event” OR “myocardial infarction” OR “acute coronary syndrome” OR “stroke” OR “heart failure” for primary research studies and reviews investigating the effect of underlying cardiovascular risk on cardiovascular complications after acute respiratory infection published in any language, from database inception to Jan 25, 2021. Of 421 studies identified, three presented estimates for the effect of cardiovascular risk on cardiovascular complications after acute respiratory infection. One prospective cohort study of individuals with community-acquired pneumonia from five North American medical centres in 1991–94 showed that arterial hypertension was associated with an increased odds of cardiac complications  within 30 days of a diagnosis of community-acquired pneumonia. The second study used clinical records from Beijing, China, to explore risk factors for cardiovascular complications after hospitalisation for community-acquired pneumonia in 2013–15, and found that patients hospitalised with community-acquired pneumonia who had cardiovascular complications had a significantly higher prevalence of hypertension than those without cardiovascular complications. The final study used UK primary care electronic health records (EHRs) to identify individuals who had a myocardial infarction or stroke in 1995–2004 and matched  controls. The authors found that individuals who had an acute respiratory infection in the previous month had an increased odds of having a first myocardial infarction or stroke, regardless of background cardiovascular risk. The effect of underlying cardiovascular risk on cardiovascular complications after acute respiratory infection therefore remains unclear. We also did a search of PubMed on Sept 28, 2021, using the search terms “*hypertensi*” OR “cardiovascular risk” AND “influenza” OR “pneumonia” OR “respiratory infection”. We searched for research articles or reviews published in any language between database inception and Jan 1, 2021. Of the 2175 studies identified, one presented estimates for the effect that cardiovascular risk has on the incidence of acute respiratory infections itself. The study used UK Biobank data to show that hypertension was independently associated with an increased risk of acute lower respiratory infections, particularly pneumonia.Added value of this studyUsing primary and secondary care EHRs from more than 4·2 million individuals in England, we found that the incidence of acute respiratory infection, particularly pneumonia, was higher in those with increased cardiovascular risk, defined as diagnosed hypertension or a QRISK2 10-year risk score of 10% or more. In addition, individuals with increased cardiovascular risk also had an elevated risk of acute cardiovascular events after an acute respiratory infection. This risk was more pronounced when QRISK2 score, which incorporates multiple factors associated with cardiovascular disease onset, was used rather than a diagnosis of hypertension alone. Therefore, QRISK2 provides a practical method to identify individuals at risk of cardiovascular complications after acute respiratory infection and to thereby prevent early-onset cardiovascular disease.Implications of all the available evidenceOur analyses and the available evidence to date indicate that individuals with increased cardiovascular risk have a higher risk of acute respiratory infection, and that these infections are more likely to trigger acute cardiovascular events than in those without increased cardiovascular risk. These findings highlight the importance of managing and reducing cardiovascular risk to reduce acute respiratory infections and their consequences. Individuals with increased cardiovascular risk have not been considered at high risk of SARS-CoV-2 infection or COVID-19 complications in policy decisions; however, hypertension has been associated with an increased risk of severe outcomes in most analyses. Individuals with increased cardiovascular risk are not typically targeted for seasonal influenza or pneumococcal vaccines, and have not been prioritised in the roll-out of COVID-19 vaccines. The prevention or treatment of acute respiratory infection in individuals with increased cardiovascular risk, as well as in those with established cardiovascular disease, could reduce the risk of cardiovascular events.Observational studies and the few randomised controlled trials (RCTs) published to date show that pneumococcal and influenza vaccines reduce the risk of cardiovascular complications when compared with placebo or no vaccine.In Europe, people with underlying cardiovascular risk but without established cardiovascular disease are not typically recommended to receive seasonal influenza or pneumococcal vaccines.10An association between high blood pressure and cardiovascular complications has been observed in individuals as young as 40 years of age.Little is known about the effect of cardiovascular risk on the risk of acute respiratory infection; however, a recent UK Biobank study showed that high blood pressure increased the risk of acute respiratory infection, particularly pneumonia and influenza.In this study, we aimed to investigate how cardiovascular risk, defined by diagnosed hypertension or QRISK2 score, is associated with the risk of acute respiratory infection and acute cardiovascular events after acute respiratory infection using 10 years of linked EHR data in England.We did a retrospective cohort study using routinely collected primary care data from the Clinical Practice Research Datalink (CPRD). The CPRD collects anonymised coded data from general practices in England through the GOLD database using the Vision clinical management system and Aurum database using the EMIS clinical management system.Consenting general practices have patient records linked to other data sources. We used linked secondary care data from the Hospital Episode Statistics Admitted Patient Care (HES APC) database, data on deaths from the Office for National Statistics (ONS), and individual-level Townsend deprivation index scores. HES APC data contain information on diagnoses made and procedures done for all National Health Service (NHS) admissions in England, coded with the International Classification of Diseases version 10 (ICD-10).The CPRD Independent Scientific Advisory Committee approved this study (19_209). The CPRD provided data on relevant HES APC, ONS, and Townsend index variables for the study population. The London School of Hygiene & Tropical Medicine provided ethical approval (17894).The study protocol and data analysis plan are available in the Eligible individuals were aged 40–64 years, not already recommended for seasonal influenza vaccination according to current UK guidelines,2), or an immunosuppressive condition.We excluded individuals who had established cardiovascular disease, received a previous pneumococcal vaccine, received an influenza vaccine within the previous 12 months, or a chronic health condition making them eligible for influenza vaccination, recorded in the CPRD at baseline. We defined conditions recommended for influenza vaccination as chronic liver disease, chronic respiratory disease, stage 3–5 chronic kidney disease, diabetes, asplenia or other splenic dysfunction, chronic neurological conditions, severe obesity , left ventricular heart failure, stroke or transient ischaemic attack, acute limb ischaemia, or cardiovascular death. We included diagnoses recorded in the CPRD or HES APC, with the codes used informed by previous studies,We considered two measures of cardiovascular risk: diagnosed hypertension and QRISK2 score. QRISK2 is a prediction algorithm that estimates an individual's 10-year risk of cardiovascular disease.Individuals were classified as having increased cardiovascular risk  or not (no hypertension or a QRISK2 score of <10%) at baseline, and their risk was updated if hypertension was recorded or new measures relevant to the QRISK2 algorithm resulted in a change in QRISK2 score from less than 10% to 10% or higher during follow-up.2], normal [BMI 18·5–24·9 kg/m2], overweight [BMI 25·0–29·9 kg/m2], or obese [BMI 30·0–39·9 kg/m2]). Consultation frequency was derived from the number of in-person or telephone consultations in the year before baseline. For analyses involving QRISK2 scores, we included only alcohol consumption and consultation frequency, as all other factors are included in the QRISK2 algorithm. We identified these included covariates using CPRD data, with data on race or ethnicity additionally collected from the HES APC database.We considered demographics, lifestyle factors, and primary care consultation frequency in analyses of hypertension and acute respiratory infection. The demographic features were age , sex , race or ethnicity , and socioeconomic status . The lifestyle factors were baseline alcohol consumption , smoking status , and BMI . To account for multiple episodes of acute respiratory infection per individual, the random-effects models included time-updated exposure by age and cardiovascular risk. We initially adjusted for age and sex before adjusting for additional covariates . A complete case-analysis approach was used in multivariable analyses. We did not do multiple imputation because data in CPRD are unlikely to be missing at random. Among individuals with an acute cardiovascular event within 1 year of acute respiratory infection, we summarised (using medians [IQRs]) the time between the infection and event. To assess the effect of cardiovascular risk on acute cardiovascular events after acute respiratory infection, we used multivariable Cox proportional hazards regression finely adjusted for time under follow-up. We used robust standard errors and initially adjusted for age and sex before adjusting for additional covariates . In all analyses, for individuals who entered and exited follow-up on the same day, we added 1 day to ensure all individuals contributed at least 1 day of follow-up. Additionally, we separately added an interaction term to our Cox random-effects models for statin, antihypertensive, or antiplatelet prescriptions, and compared the results to models without interaction.I2 statistic. Second, we excluded only individuals eligible for both pneumococcal and influenza vaccines , residing in more deprived regions (627 333 [18·3%] of 3 434 620 vs 105 045 [13·6%] of 772 985), and current or former smokers (2 002 856 [60·1%] of 3 334 866 vs 393 016 [52·6%] of 747 925) than in the GOLD dataset  were included in the final cohort . Individ dataset .Figure 1526 480 (12·5%) of 4 212 930 individuals had diagnosed hypertension: 347 418 at baseline and a further 179 062 during follow-up. 607 087 (14·4%) individuals had a QRISK2 score of 10% or higher: 402 594 at baseline, and a further 204 493 had a score that increased to 10% or higher during follow-up. 239 184 (5·7%) individuals had both hypertension and a QRISK score of 10% or higher.586 147 episodes of acute respiratory infection were recorded among 442 408 individuals: 107 639 episodes of influenza or influenza-like illness and 31 068 episodes of pneumonia. The incidence of all-cause acute respiratory infection and pneumonia increased with age, with the exception of the incidence of acute respiratory infection among those with a QRISK2 score of 10% or higher, for which there was no age trend, and the incidence of influenza or influenza-like illness decreased with age . The incIn the unadjusted analysis, there was an increased incidence of acute respiratory infection among individuals with hypertension compared with those without hypertension (IRR 1·38 [95% CI 1·36–1·39]) and similarly for individuals with a QRISK2 score of 10% or higher compared with those with a QRISK2 score of less than 10% (1·52 [1·50–1·53]). After adjustment for confounders, the association between hypertension and acute respiratory infection was substantially reduced (IRR 1·04 [95% CI 1·03–1·05]), but the association between a QRISK2 score of 10% or higher and acute respiratory infection remained  who had an acute respiratory infection, 4169 (0·9%) had an acute cardiovascular event within 1 year. 1606 (38·5%) of these individuals had pneumonia .985 (11·2 events per 1000 person-years [95% CI 10·5–12·0]) acute cardiovascular events occurred in individuals with hypertension, 3184 (5·8 events per 1000 person-years [5·6–6·0]) in those without hypertension, 1526 (17·5 events per 1000 person-years [16·7–18·5]) in individuals with a QRISK2 score of 10% or higher, and 2643 (4·8 events per 1000 person-years [4·6–5·0]) in those with a QRISK2 score of less than 10% . The num2106 (50·5%) of the 4169 acute cardiovascular events occurred within 30 days of an acute respiratory infection , but thevs no hypertension HR 4·63 [95% CI 2·68–7·99]; QRISK2 score of ≥10% vs <10% 6·93 [4·43–10·83]), acute coronary syndrome , and cardiovascular death .After adjustment for confounders, hypertension (hazard ratio [HR] 1·98 [95% CI 1·83–2·15]) and a QRISK2 score of 10% or higher (3·65 [3·42–3·89]) remained associated with acute cardiovascular events after acute respiratory infection . When acvs no antihypertensives 4·04 [3·76–4·34], statins 2·22 [1·83–2·69] vs no statins 3·93 [3·67–4·21], antiplatelets 1·82 [1·36–2·44] vs no antiplatelets 3·68 [3·45–3·93]; In the analysis stratified by prescription of antihypertensive, statin, or antiplatelet drugs, there was no association between hypertension status and acute cardiovascular events after acute respiratory infection among individuals with a prescription , but the association remained for those without a prescription . A QRISK2 score of 10% or higher remained associated with acute cardiovascular events after acute respiratory infection in patients with and without a prescription of antihypertensives, statins, or antiplatelets, but was higher among individuals without a prescription  than by diagnosed hypertension (2·0 times). Associations were similar for all-cause acute respiratory infection, influenza-like illness, and pneumonia. Half of the acute cardiovascular events occurred within 30 days of acute respiratory infection.Our finding that the incidence of acute respiratory infection was elevated among individuals with increased cardiovascular risk is consistent with the results of a recent UK Biobank study, which examined the association between blood pressure and the risk of different respiratory infections.Previous studies have reported transient increases in the risk of myocardial infarction and stroke after acute respiratory infection.S pneumoniae, could also exacerbate atherosclerotic processes. The infectious agent could have direct effects on vascular cells, or the infection could induce haemodynamic, inflammatory, and procoagulant processes. The release of proinflammatory cytokines in response to an infection can mediate atherosclerosis or directly affect plaque rupture.Several mechanisms could explain the associations between cardiovascular risk factors, acute respiratory infection, and cardiovascular disease. Hypertension could promote immune dysregulation, leading to infection, or the endothelial dysfunction caused by hypertension, hyperlipidaemia, and diabetes could promote infection.A strength of our study is that we used large, population-based, linked datasets generalisable to the UK population. We also compared results across two measures of cardiovascular risk. The marked increase in the incidence of acute cardiovascular events after acute respiratory infection in individuals with a QRISK2 score of 10% of higher compared with those with diagnosed hypertension is consistent with the multiple cardiovascular risk factors accounted for in the QRISK2 score.Our selected study population should have reduced confounding. We included only individuals without chronic health conditions, who were not thought to be at high risk of acute respiratory infection or complications related to acute respiratory infection, and who were not recommended for influenza vaccination in England, according to current guidance. However, the selective study population prevented comparison of the incidence of acute respiratory infection and acute cardiovascular events after acute respiratory infection among individuals with established cardiovascular disease.In England, diagnoses of acute respiratory infection are based primarily on clinical judgement, with most cases not laboratory confirmed. We included only codes that were most likely to be representative of systemic infection, which could plausibly induce atherosclerotic processes. However, clinically diagnosed influenza is poorly defined.We might have misclassified QRISK2 score due to missing data for variables used in its calculation. However, the similar results from primary care recorded and captured in CPRD and our calculated QRISK2 scores suggest minimal misclassification. Furthermore, we adjusted for consultation frequency, as individuals who infrequently attend primary care services are unlikely to have biometric measures such as BMI or blood pressure recorded. We used a pragmatic definition for hypertension based on coded diagnoses only; this coded diagnosis corresponds to how, if eligible, individuals would be identified for influenza and pneumococcal vaccination in primary care. We are likely to have captured both controlled and uncontrolled hypertension. In the stratified analysis, 38% (25 843 of 68 731) of individuals with diagnosed hypertension had not been prescribed antihypertensive drugs in the year before the acute respiratory infection. Conversely, only 3% (14 912 of 458 069) of individuals without a diagnosis of hypertension were prescribed antihypertensive drugs. Possible misclassification could have biased the results towards the null, which could explain the small association observed between hypertension and acute respiratory infection compared with the larger association for QRISK2 scores in our study and blood pressure reading-defined hypertension in the UK Biobank study.We assumed that acute cardiovascular events occurring after acute respiratory infection were due to infection. However, some events could have been unrelated, particularly those that occurred several months after infection. The possibility of unrelated events is consistent with our finding of a longer median time between acute respiratory infection and acute cardiovascular events in individuals with increased cardiovascular risk compared with those without an increased risk, as those with an increased cardiovascular risk are more likely to have a cardiovascular event regardless of acute respiratory infection.Our findings emphasise the importance of improved cardiovascular risk management, which could reduce the incidence of acute respiratory infection and its cardiovascular consequences. The COVID-19 pandemic has highlighted this need. Preventive cardiovascular treatments, particularly among individuals with a QRISK2 score of 10% or higher, could reduce acute respiratory infection-related complications. A meta-analysis of nine observational studies showed a 41% reduction in the odds of mortality within 30 days of having pneumonia among statin users.Typically, individuals with increased cardiovascular risk do not receive seasonal influenza or pneumococcal vaccines. Previous RCTs have shown that the influenza vaccine provides secondary prevention of cardiovascular disease.In conclusion, the results of our study suggest that the incidence of acute respiratory infection, particularly pneumonia, is increased in people with high cardiovascular risk, and that the incidence of acute cardiovascular events after acute respiratory infection is also increased in these individuals. The QRISK2 score provides a better measure of the risk of a first cardiovascular event following acute respiratory infection than a diagnosis of hypertension alone. Therefore, the QRISK2 score could be used not only to identify individuals who require cardiovascular risk management, but also to target prevention and treatment of acute respiratory infection to individuals at increased risk of cardiovascular events following infection.The data used for this study were obtained from the CPRD. All CPRD data are available via an application to the Independent Scientific Advisory Committee (see https://www.cprd.com/Data-access). Data acquisition is associated with a fee and data protection requirements. This study is supported by code lists used to define each health condition, which have been made openly available at https://doi.org/10.17037/DATA.00002240. Our data management and analysis computer code is available via GitHub at https://github.com/jenAdavidson/cvrisk_mace_ari. All code is shared without investigator support.AB reports receiving grants from AstraZeneca, UK Research and Innovation, and the National Institute for Health Research (NIHR). CW-G reports receiving grants from the Wellcome Trust and the British Heart Foundation; receiving speaker fees from Sanofi Pasteur; and participating in a data safety monitoring board for an investigator-led trial of the effect of influenza vaccination after heart attack on future cardiovascular prognosis (NCT02831608) from January, 2019, to April, 2020. HIM is funded by the NIHR Health Protection Research Unit in Immunisation. JAD is funded by the British Heart Foundation through the grant received by CW-G. All other authors declare no competing interests.


At quasi-static rates, the monodomain soft-elastic LCE dissipated 45% of strain energy while comparator materials dissipated less than 20%. At strain rates up to 3000 s−1, our soft-elastic monodomain LCE consistently performed closest to an ideal-impact absorber. Drop testing reveals soft-elasticity as a likely mechanism for effectively reducing the severity of impacts – with soft elastic LCEs offering a Gadd Severity Index 40% lower than a comparable isotropic elastomer. Lastly, we demonstrate tailoring deformation and buckling behavior in monodomain LCEs via the printed director orientation.Soft-elasticity in monodomain liquid crystal elastomers (LCEs) is promising for impact-absorbing applications where strain energy is ideally absorbed at constant stress. Conventionally, compressive and impact studies on LCEs have not been performed given the notorious difficulty synthesizing sufficiently large monodomain devices. Here, we use direct-ink writing 3D printing to fabricate bulk  is promising for impact-absorbing applications but due to the lack of synthetic procedures which give monodomain devices of sufficient size, impact studies on LCEs have not been performed. Here the authors use direct-ink writing to fabricate bulk monodomain LCE devices and study their compressive soft-elasticity. In 2001, Clarke et al. reported that LCEs—which incorporate the anisotropic ordering of liquid crystals into elastic polymer networks—demonstrate elevated loss tangents (tan(δ)= G”/G’) as high as 1.5 when held at temperatures between their glass transition and nematic-to-isotropic transition temperatures 6. These values of tan(δ) correspond to highly viscous and dissipative materials and are far greater than values (~0.1)/found in traditional isotropic elastomers8.One of the most exciting but often overlooked applications for liquid crystal elastomers (LCEs) is for use in strain-rate-dependent impact absorbing devices11. Azoug et al. reported on the large and strain-rate-dependent tensile hysteresis between loading and unloading stress-strain curves for polydomain  and uniform devices. However, the recent application of direct-ink writing (DIW) 3D printing to the fabrication of LCE devices offers a new route to producing arbitrarily sized monodomain LCEs. In DIW, an LC oligomer is shear aligned into a monodomain when extruded through a nozzle—a state which is then fixed by subsequent photo-crosslinking of the oligomers into a network  is key to our mechanical and impact studies as well as the end-application of LCEs as impact-absorbing materials. The monodomain liquid crystalline alignment of the printed LCE devices is readily seen when viewing a single printed layer (310 µm thick) via crossed-polarizing microscopy. When the print direction is oriented at 45°, a highly uniform bright state is seen  LCE in 3D-printed devices when compressed parallel  of each material measured using dynamic mechanical analysis (DMA). The peak of each material’s tan(δ) shows that all materials have glass transition temperatures (Tg) within 1 °C of each other. Additionally, in the rubbery regime above Tg, these materials have comparable storage moduli. At room temperature (20 °C), the monodomain LCE has an anisotropic storage modulus of 1.1 and 3.6 MPa for small strains parallel and perpendicular to the director, respectively. The storage moduli of LCE PD and the BPA elastomer lies between the values for the monodomain LCE at 2.0 and 1.4 MPa, respectively. The tan(δ) curves also show that these materials have elevated tan(δ) plateaus above Tg. While this is expected for LCEs10, an elevated tan(δ) was not expected for the BPA elastomer. Overall, the high tan(δ) of the BPA elastomer makes this an excellent material to compare to the LCEs, allowing us to directly compare the influences of viscoelasticity alone (BPA) versus viscoelasticity coupled with mesogen rotation (LCE).The LCE PDs and BPA elastomer’s crosslink densities were tailored to ensure comparable thermomechanical properties as the DIW printed LCEs. Figure ® Durometer-70 , a commercial polyurethane-based impact absorbing and vibration-isolating material. The compressive load curves in Fig. −4 s−1).In addition to the materials already described, we also compare these materials against Sorbothane−4 and 1 s−1 we used a uniaxial testing machine, for rates above 800 s−1, we used a Kolsky (split-Hopkinson) bar. In each case, samples were loaded to compressive true strains of −0.7 . Samples used had a low aspect ratio to avoid any buckling of the samples during testing (see “Methods”). True stresses were calculated using a constant volume and ideal deformation  assumption by multiplying the nominal stress by the deformation of Compressive load curves for LCE MD ior Fig. . For ratmentclass2pt{minim−4, 1 (100), 800 (8 × 102), and 3000 (3 × 103) s−1. In these figures, the true stresses have been normalized against the stress level of an ideal absorber of strain energy (see “Methods”). Presenting the data in this way enables comparison of each material’s stress-strain response at each nominal strain rate and how the load curves’ characteristic behavior changes with increasing nominal strain rate. For reference, on each graph we also show the expected behavior of an ideal absorber and for a classically elastic and volume conserving material (an incompressible neo-Hookean solid), described byFigure −4 s−1 we can identify three types of material behavior. The first type is classical elasticity from materials that did not undergo mesogen rotation , where the LCE MD 24. Their results at impact rates (3300 s−1 and greater) show that at low true strains (<0.2), polyureas demonstrate improvements similar to LCE MD At impact rates of 800 and 3000 sIn addition to the loading and storage of energy during a compressive deformation, for impact-absorbing applications it is also important to consider the magnitude Fig.  and perc−4 to 1 s−1, the LCE samples dissipate similar magnitudes of strain energy and have similar rate dependencies. Even though the LCE MD −4 s−1 (~25% of the LCE’s dissipatation); however, this increases with a greater strain rate dependency (~50% of that LCE MD −1). At 10−4 s−1, SD-70 also dissipates significantly less energy than the LCEs, but unlike the BPA-elastomer this disparity increases with strain rate.Figure nse Fig. , it dissnse Fig. . Furthertes Fig. . In comp−4 s−1, rising to 89.1 ± 0.8% at 1 s−1. By comparison, LCE MD −4 and 1 s−1, respectively. While at room temperature, these slower rates do not relate to impact conditions, they provide an insight to the enhanced dissipative behavior at higher temperatures via the time-temperature superposition principle. The BPA shows a curiously different response. Looking back to Fig. −1, the BPA elastomer can dissipate a similar percentage of loaded energy (82 ± 6%) to LCE MD Figure ion Fig. . HoweverFrom the load curves, we can deduce that at low strains, LCE MD −2 s−1 indicates a change in the thermomechanical response of the BPA elastomer in a way which appears to make it suitable for dissipating mechanical energy. This is attributed to the time-temperature superposition principle, in which an increase in strain rate is shifting the material closer to its glass transition, from an elastomeric to a leathery response with increased viscous effects. However, this also means that at increasing temperatures, one would expect the BPA elastomer’s dissipative capability to notably drop off when compared to the LCEs as the material quickly increases in its elasticity.The BPA elastomer’s comparatively sharp increase in percentage dissipated energy at a threshold rate of ~10By comparing the energy dissipated as a function of strain rate Fig. , we can δ) of each material at various levels of compressive strain. The 1 Hz sinusoidal strains of 0.1% amplitude correspond to a root mean square nominal strain rate of 5 × 10−3 s−1. The tan(δ) of all the materials tested have differing extents of strain-dependency. For the LCEs, the differences can be linked to the presence of soft-elastic effects. For the non-soft elastic LCE MD δ) remains constant with strain at a base level of ~0.35. For the polydomain soft-elastic LCE PD, tan(δ) is initially elevated at ~0.6, but then quickly converges to the base level. The monodomain soft-elastic LCE MD δ) similar to that of LCE PD; however, this is maintained for a greater range of strains before converging to the based level. Given that the monodomain soft-elasticity in LCE MD δ), between ~0.8 at low strains and ~0.6 at high strains, greater than for any other material tested here. Despite having the highest tan(δ) values throughout compression, the LCE MD This inferred behavior is supported by Fig. 2 cross-sectional area and 7.5 mm height were impacted by 2 kg cylindrical mass of radius 38 mm (see methods). Impact testing is fundamentally different from compressive testing as the strain rate of the sample is not constant throughout the duration of the test. The LCE MD Rate-dependent compressive mechanical testing has shown that monodomain soft elasticity offers several enhancements in an elastomer’s ability to dissipate energy. Next, we consider the performance during impacts simulated by drop testing Fig. . In our For illustrative purposes, Fig. Figure 25. These effects can be encapsulated and quantified using the Gadd Severity Index (GSI) which is calculated via the following integral26:For head impacts, the severity of an impact and the probability of a person suffering a concussion significantly increases nonlinearly with peak accelerationFigure 27. We now demonstrate the additional levels of control over compressive mechanical behavior possible in DIW-printed monodomain LCE devices in high aspect ratio devices where buckling effects are likely (see “Methods”). The DIW-printing process imparts liquid-crystal alignment into the material to control anisotropy and buckling behavior .Compressing along the director Fig.  yields ttor Fig.  initiallIn this work, we explored the effects of soft elasticity in bulk monodomain LCEs under compression, which has potential use in impact absorbing devices. Through careful optimization of DIW print conditions, we were able to fabricate (to the best of our knowledge) the largest monodomain LCE devices reported to date, and which allowed us to conduct an exceptionally in-depth study of LCE compressive mechanical properties. Our results show that by applying compressions along the director in monodomain LCEs, soft elasticity is observed which translates to enhanced dissipative characteristics over conventional elastomers and polydomain LCEs, like those previously studied by ourselves and others.−1) is quickly dissipated. In practically all metrics tested, the LCE MD Our monodomain soft-elastic LCE devices are capable of dissipating large quantities of strain energy at relatively constant levels of stress – a close-to-ideal behavior which avoids peaks in stress, and almost all of which  for their low-cost and availability. Future studies should seek to optimize material design and understand how LCE dynamics, i.e. the different relaxation processes and their timescales, affect load curve shape, rate dependency and dissipation. This research will undoubtedly lead to LCE devices of even greater performances than those reported here. At the same time, there is evidently much richness yet to be explored in understanding and exploiting the anisotropy-controlled buckling deformations of LCEs. One can easily envisage how such deformations could be used to further optimize the nature of LCE deformations for a wide range of impact scenarios, for instance, in controlling rotational accelerations associated with oblique impacts.In short, we have shown here that coupling the long-famed anisotropic non-linearity of LCEs with DIW 3D printing opens enormous application potential of impact absorbing LCE devices, with much physics and mechanics yet to be explored.Here, we have demonstrated optimized DIW 3D printing of LCEs which we used to create the largest known monodomain devices to date. By testing these in compression over eight decades of strain rate—spanning quasi-static and impact rates, we have shown how the monodomain soft elastic mechanism enhances an elastomer’s capability to load and dissipate mechanical impact energy. The monodomain soft elastic LCEs demonstrated the closest stress-strain response to that of an ideal absorber and its rate dependency led to a relatively consistent performance over drop tests of differing intensities. We also showed how compressive deformations can be further enhanced by using the DIW printing direction to control the buckling characteristics of the LCE. This work brings the realization of LCE devices closer as it demonstrates a scalable and industrially realistic fabrication method along with enhanced material behavior not seen in conventional elastomers.3-7 below are shown in Supplementary Fig, 3, CAS 4970-87-7), butylated hydroxytoluene , 2-Hydroxy-4’-(2-hydroxyethoxy)-2-methylpropiophenone  and N,N,N′,N″,N″-Pentamethyldiethylenetriamine . Polydomain LCEs were synthesized with the same chemicals, but with the addition of pentaerythritol tetrakis(3-mercaptopropionate) . The non-mesogenic acrylate-capped oligomers were synthesized with the same components as the LC oligomer, but with RM257 replaced with the non-mesogenic diacrylate bisphenol A dimethacrylate . RM257 was purchased from Wilshire Technologies, all other components were purchased from Sigma Aldrich and all components were used as received. Sorbothane Duro 70 was purchased from Isolate it! And cut to size for testing.Structures for chemicals 15. Briefly, BHT , RM257  and HHMP  were added to a glass vial and melted together in a water bath set at 70 °C. The melted components were thoroughly mixed, and bubbles/dissolved gases removed via vacuum before EDDT  and PMDETA  were added and the mixture again mixed and degassed. The mixture was then transferred to the DIW-printing barrels and left in an oven set at 70 °C for half an hour to start the Michael addition :EDDT :PETMP  = 1.000:0.871:0.065 as this had an even balance of acrylate groups to thiol groups – ensuring that after the Michael addition (assuming complete conversion) no excess acrylate or thiol groups remained. In this synthesis, we used 0.052 g, 0.235 mmol of BHT and 0.072 g, 0.319 mmol of HHMP. PETMP was added at the same time as the EDDT and once all components were combined together, the mixture was poured into molds as opposed to the printing barrels.For the synthesis of the non-liquid crystalline BPA-ink, the same oligomerization process used for the LC oligomer was used except for the following differences. First the non-mesogenic diacrylate monomer BPADMA was used in place of RM257 and in a ratio of BPADMA :EDDT  = 1:0.96. Second, we used 1.05 g, 4.78 mmol of BHT, 1.072 g, 7.48 mmol of HHMP and 0.849 g, 4.90 mmol of PMDETA.Given the relatively low number of monomer units in each oligomer chain, small variations in measured material quantities translate to significant variations in average oligomer chain length. Therefore, to ensure comparable samples for each test, all materials of each type were prepared from single batches of prepared material.DIW printing was performed using a Hyrel Engine HR 3D printer equipped with a KRA-2 print head for heating and extruding LC oligomers along directed print paths. Barrels containing printable oligomer were installed in the KRA print head which was set at 65 °C for the LC-ink (left for an hour prior to printing for equilibration) and kept at ambient conditions for the BPA-ink (due to its significantly lower viscosity). During printing, materials were extruded through a Tecdia Arque-S 5060 nozzle which had an internal diameter of 500 µm at the nozzle tip. G-code toolpaths controlling the print head’s motion, printer settings and volumetric rate of material extrusion were created using in-house developed python scripts which also aided tuning of the print parameters (described below). During extrusion, the extruded material was exposed to UV light from LEDs surrounding the nozzle. Post-printing, the devices  were fully cured through exposure to high-intensity UV light in a UVP CL-1000  chamber for 2 h. Devices used in tensile stress-strain and DMA tests had far greater surface area-to-volume ratios and so were post-cured for 30 min. All printed devices were periodically rotated during post-curing to ensure even exposure.Print conditions for our LCE were optimized through printing a series of matrices tuning, in turn, the various print parameters. First, we printed meanders of single lines - simultaneously optimizing for the volumetric extrusion rate and the nozzle height above the print surface. Liquid crystalline alignment quality was assessed via polarizing microscopy, with the parameters offering the greatest apparent uniformity in, and contrast between the bright and dark states chosen as the ideal parameters. Next, using these parameters we printed series of meandering lines of different spacing between print lines until the print lines were close enough to bond to each other from a single printed sheet. Care was taken not to print lines too close to one another—which would diminish the level of liquid-crystalline alignment present. By measuring the thickness of the printed sheets, we deduced the ideal layer height to use for multi-layered devices.3 and ~0.06 g) of DIW-printed LCE, cut a from a larger 20 ×20 × 37 mm3 printed block  was recorded and then each sample was placed in a full 12 ml vial of toluene (a good solvent of LCEs) for 72 h. Samples were then removed and placed under vacuum in an oven set at 70 °C. Sample masses were measured periodically and were found to be constant after 48 hours of drying. The remaining mass of each sample after 48 h of drying (mf) was measured again and the gel fraction, GF, calculated via, GF=Tests were performed on 9 samples  and were subject to 1 Hz oscillations of 0.1% strain amplitude. Samples were heated to 130 °C and allowed to equilibrate for 10 min to erase their thermal history before data were collected during a temperature sweep to −30 °C at 2 °C min−4 s−1.Tensile mechanical tests of the printed LCEs  to ensure the platen was in contact with the top of the sample. After dwelling at this position for 600 s, the samples were loaded to 50% nominal strain and unloaded 0% to strain at strain rates of 10−4 (taken as quasi-static), 10−3, 10−2, 0.1 and 1 s−1. From the data collected, the dissipated strain energy density (area between loading and unloading curves) and percentage dissipated energy (area between load curves relative to area under loading curve) were calculated. For display in Fig. n ≥ 3) were averaged.For comparisons of each material’s compressive load curve and rate dependency, each device was tested by application of an initial 10 kPa preload stress (~1 N and loaded at 0.01 N sδ), at different strains across each material’s compressive load curve were performed using the Electroforce’s DMA Application. Samples were loaded with a series of incremental forces . At each load increment, the samples were allowed to stress relax for 10 min before being subjected to 0.1% strain amplitude oscillations for DMA tests. Using each incremental load, the sample strain was extracted using the quasi-static compressive load curves measured for each material. Each material was repeat tested 5 times.Measurements of the loss tangent, tan printed devices was assessed by subjecting the samples to a 10 kPa preload force (loaded at 0.01 N s−1) and then loaded to 50% and unloaded at a rate of 10−3 s−1. Photographs were taken of each sample in their unstrained and maximally strained states and from which the director orientation (on the face seen by the camera) could be traced using the print lines which were visible.The buckling characteristics of higher aspect ratio  bar was used to measure the high nominal strain rate compression response of the materials beyond 1 s3 (2 mm thick), dimensions which aided the stress equilibration process. Experiments were carried out at nominal strain rates of 800, 1600, and 3000 s−1 with n = 3 at each condition. Samples were subjected to a minimum of 50% nominal strain at each condition for comparison with quasi-static experiments. For display in Fig. The dimensions of the Kolsky compression samples were approximately 2 × 5 × 5 mm33.The supplementary information provides further details showing the specimens reached constant strain rate, dynamic equilibrium, and were not affected by radial inertia or friction. The supplementary methods cite refs. First, for each material and at each nominal strain rate (using their averaged load curves), the amount of loaded strain energy, An ideal absorber would instead absorb this energy over this strain range at a constant stress level of 2 cross-sectional area and 7.5 mm height. Each material was subjected (at n = 3 for each condition) to drop tests with the mass dropped from heights of 0.25, 0.50, 0.75, and 1.00 m . Table −2) was detected—a displacement position taken as the top of the impacted sample. The impact velocity was deduced from a separately determined calibration curve linking drop height to impact velocity. Continued displacement was calculated using the impact velocity and twice integration of the accelerometer’s readings.Drop tests were performed using an in-house built test frame. A uniaxial piezoresistive accelerometer (Meggit model 7264B-2000) was used for measuring linear accelerations. Data were acquired at a sample rate of 25k Hz using a National Instruments 9237 data acquisition bridge module. The accelerometer was attached to a cylindrical 2 kg mass (38 mm radius) mounted on a guided linear rail that was dropped on samples of typical dimensions 12 × 12 mmGSI for ideal absorbers, capable of constant deceleration to 100% compressive nominal strain, were calculated using the impact velocity and height of each sample to determine the ideal-impact time and deceleration value. The GSI of each sample at each drop height was compared to this value of the idealized absorber.Supplementary InformationPeer Review File


Cardinium and Wolbachia, in the sex allocation of Pezothrips kellyanus, a haplodiploid thrips species with a split sex ratio. In this species, irrespective of infection status, some mated females are constrained to produce extremely male-biased broods, whereas other females produce extremely female-biased broods. We analysed brood sex ratio of females mated with males of the same infection status at two temperatures. We found that at 20 °C the frequency of constrained sex allocation in coinfected pairs was reduced by 27% when compared to uninfected pairs. However, at 25 °C the constrained sex allocation frequency increased and became similar between coinfected and uninfected pairs, resulting in more male-biased population sex ratios at the higher temperature. This temperature-dependent pattern occurred without changes in endosymbiont densities and compatibility. Our findings indicate that endosymbionts affect sex ratios of haplodiploid hosts beyond the commonly recognised reproductive manipulations by causing female-biased sex allocation in a temperature-dependent fashion. This may contribute to a higher transmission efficiency of CI-inducing endosymbionts and is consistent with previous models that predict that CI by itself is less efficient in driving endosymbiont invasions in haplodiploid hosts.Maternally inherited bacterial endosymbionts that affect host fitness are common in nature. Some endosymbionts colonise host populations by reproductive manipulations  that increase the reproductive fitness of infected over uninfected females. Theory predicts that CI-inducing endosymbionts in haplodiploid hosts may also influence sex allocation, including in compatible crosses, however, empirical evidence for this is scarce. We examined the role of two common CI-inducing endosymbionts,  Wolbachia and Cardinium bacteria are ubiquitous endosymbionts of arthropods  production, increasing the proportion of infected individuals which then increases the endosymbionts’ prevalence and invasion success Turelli . HoweverWolbachia-infected spider mite Tetranychus urticae , a native Australian haplodiploid thrips species which is naturally infected with one Cardinium strain and one Wolbachia supergroup B strain  have evolved haplodiploidy independently from Hymenoptera and other haplodiploid lineages such as wasps (Hymenoptera), scales and whiteflies (Hemiptera), and mites (Acariformes)  temperature moderates any such endosymbiont effects on constrained sex allocation, and (3) any such temperature effects on endosymbiont-influenced sex allocation correlate with temperature-dependent changes in endosymbiont densities and/or CI strength. Addressing these questions will help further uncover the epidemiological dynamics of endosymbionts in haplodiploid host populations and reveal factors that drive the evolution of constrained sex allocation and split sex ratios.Previous laboratory and field studies of P. kellyanus originally established with individuals collected from the Riverland, South Australia, was used for this experiment. This population was naturally coinfected (ICW) with one Cardinium strain and one Wolbachia supergroup B strain  were treated with a 5% rifampicin (w/v) solution for three generations  and uninfected (U × U) individuals; experiment 3 also included the CI cross (U × ICW). Singly infected lines were not available when the experiments were conducted. Therefore, experiments 1 and 2 addressed the combined effect of both endosymbionts on offspring number and sex ratios of females reared at 20 °C only, whereas in experiment 3, the offspring number and sex ratio effects of the coinfecting endosymbionts were assessed at 20 and 25 °C. At these temperatures different sex ratios have previously been reported for P. kellyanus at the population level  number and sex ratio were measured at the adult stage. Cardinium and Wolbachia infections of each line were confirmed by PCR screening of randomly selected 20 females and 20 males per line before each experiment commenced.Data were collected in three consecutive crossing experiments Fig.  that assTypha sp. pollen was added to increase female fecundity  for recording of the offspring number and sex ratio  which had been reared at controlled densities. For this, F0 females and males of each line were placed into small round plastic containers , containing one fully ripe lemon fruit each, to oviposit for 24 h after which the adults were removed  with  in the “lme4” package in R version 3.5.1 (R Development Core Team 2015). We further assessed the role of endosymbiont and temperature on sex ratio for constrained and unconstrained females separately. According to a Shapiro–Wilk test the sex ratio data had a non-normal distribution; therefore, we used a Wilcoxon rank sum test in R to compare group means.Upon emergence of all adults, number and sex ratio of offspring (F2) produced by each individual mother was recorded. As in other similar studies, any pair that had produced fewer than ten offspring was excluded , experiment 3 also included incompatible pairs (U × ICW) at both 20 and 25 °C. This enabled us to assess whether the strength and type of CI changed with temperature. This was achieved by comparing the number of male vs. female offspring across the two temperatures. According to a Shapiro–Wilk test the normality assumption was not met for the CI data. Therefore, the CI dataset was processed using Aligned Rank Transform in the ARTool package  with the “lme4” and “car” packages in R.In another experiment endosymbiont densities were measured after rearing thrips for two consecutive generations (G1-G2) across four different temperature regimes: (1) both generations at 20 °C (20–20); (2) both generations at 25 °C (25–25); (3) G1 at 25 °C and G2 at 20 °C (25–20); (4) G1 at 25 °C and G2 at 30 °C (25–30) , whereas other mated females were constrained and had M broods   produced F broods with an average sex ratio of 1.7% males, while <58% of 66 mated females without endosymbionts (U) produced F broods with an average sex ratio of 4.5% males  . Moreover, in experiment 3 the proportion of females producing M broods was higher at 25 °C  than at 20 °C  . Because of a marginally significant interaction of temperature and endosymbiont infection status on the model , a step-down analysis of the endosymbiont effect on sex ratio was performed for each thermal treatment separately. This revealed that the effect of endosymbionts on M brood production was only detectable at 20 °C , whereas the M brood production was similar between mated ICW and U females at 25 °C . Furthermore, our model did not detect an effect of constrained sex allocation on offspring number .Mated es) Fig. . At 20 °CW females producing F broods had a lower percentage of male offspring  than mated unconstrained U females producing F broods at both 20 and 25 °C  at 20 and 25 °C (experiment 3) resulted in male-only offspring, and, therefore the expression of CI was complete and independent of temperature , as also observed in a previous study   Fig. ; Table 2Wolbachia densities were substantially higher (between 8 and 92-fold) than Cardinium densities. Furthermore, there was a strong effect of sex on Wolbachia densities with higher normalised Cq values for fbpA  and coxA  in females than in males. However, no effect of sex was detectable on Cardinium densities, with the analysis performed on gyrB Cq values . Furthermore, temperature did not significantly affect densities of Wolbachia  or Cardinium  .Overall, P. kellyanus females mated with compatible males experiencing constrained sex allocation was diminished by the presence of both Cardinium and Wolbachia at 20 °C, and this endosymbiont effect was temperature-sensitive as it disappeared with the increase of temperature to 25 °C. These findings may explain previous studies which demonstrated that the population sex ratios of P. kellyanus became less female-biased when reared at higher temperatures in the laboratory  in a haplodiploid host species, and this occurred independently from any CI effects on sex allocation, and in a temperature-dependent way. We found that the proportion of Our finding of temperature-sensitive sex allocation is consistent with sex ratio patterns observed in several other haplodiploid taxa (Bondy and Hunter 2019). This has been recognized in some Hymenoptera species in which exposure to higher temperatures can cause increased maternal investment in male production , whereas, for the compatible (rescuing) crossing type ICW × ICW it was found that the frequency of females suffering from constrained sex allocation  increased at the higher temperature. This could suggest temperature-sensitive changes in the rescue (but not the induction) of CI. However, we found that Cardinium and Wolbachia densities in both males and females remained steady across the examined temperature regimes. Therefore, increased constrained sex allocation seen in compatible crosses at the higher temperature may not be due to an overall decline in endosymbiont density in females. Nevertheless, CI may still arise in compatible crosses at higher temperatures due to a shift in endosymbiont localization patterns , because constrained females are smaller and produce smaller eggs than unconstrained females  to facilitate fertilization success and, therefore, female production. Such fitness-dependant sex allocation has been revealed for a parasitic wasp species  and may occur through changes in sex allocation in compatible crosses that can lead to increased female production. In haplodiploid populations, production of uninfected males as an outcome of CI can limit the invasion success of CI, as uninfected females can maintain their fitness by mating with these uninfected males (Vavre et al. Cardinium and Wolbachia may have different evolutionary trajectories and molecular mechanisms to affect hosts (Penz et al. P. kellyanus separately. Finally, the temperature-dependent endosymbiont effect on sex ratio in P. kellyanus may provide insights into the evolution of temperature-dependent sex allocation mechanisms in many other arthropods.In summary, our study demonstrated that the role of common endosymbionts such as Supplementary Information


Watershed anthropogenic CO2 emissions (1.56 million Mg C y−1) far exceeded the annual mangrove forest C storage rates . A combination of maintaining healthy mangrove forests and reducing anthropogenic emissions might be necessary to mitigate greenhouse gas emissions in urban, tropical areas.Mangroves sequester significant quantities of organic carbon (C) because of high rates of burial in the soil and storage in biomass. We estimated mangrove forest C storage and accumulation rates in aboveground and belowground components among five sites along an urbanization gradient in the San Juan Bay Estuary, Puerto Rico. Sites included the highly urbanized and clogged Caño Martin Peña in the western half of the estuary, a series of lagoons in the center of the estuary, and a tropical forest reserve (Piñones) in the easternmost part. Radiometrically dated cores were used to determine sediment accretion and soil C storage and burial rates. Measurements of tree dendrometers coupled with allometric equations were used to estimate aboveground biomass. Estuary-wide mangrove forest C storage and accumulation rates were estimated using interpolation methods and coastal vegetation cover data. In recent decades (1970–2016), the highly urbanized Martin Peña East (MPE) site with low flushing had the highest C storage and burial rates among sites. The MPE soil carbon burial rate was over twice as great as global estimates. Mangrove forest C burial rates in recent decades were significantly greater than historic decades (1930–1970) at Cañno Martin Peña and Piñones. Although MPE and Piñones had similarly low flushing, the landscape settings  and urbanization (high vs low) were different. Apparently, not only urbanization, but site-specific flushing patterns, landscape setting, and soil fertility affected soil C storage and burial rates. There was no difference in C burial rates between historic and recent decades at the San José and La Torrecilla lagoons. Mangrove forests had soil C burial rates ranging from 88 g m Mangrove forests globally sequester significant volumes of organic carbon  because of the long-term burial associated with their high primary production and anoxic sediments, which slow or prevent carbon (C) remineralization . AdditioNow, in the Anthropocene Epoch, with its associated stressors such as global climate change, it is more important than ever to examine the effects of local urbanization on C sequestration in coastal mangroves . The glo−2, primarily located in the urban municipalities  associated with the city of San Juan, Puerto Rico , White [Laguncularia racemosa (L.) C.F. Gaertn], Black [Avicennia germinans (L.) L.], and Button [Conocarpus erectus (L.)] mangrove species, and numbered over five million trees (with diameter at breast height ≥2.54 cm) in 2011  dated cores from the mangrove study sites we account for recent and historic decadal soil accretion rates. We estimate the mangrove forest C sequestration (aboveground plus soils) at the scale of the local mangrove forest and the entire estuary. For comparative purposes we examine the magnitude of the estuary-wide mangrove forest C sequestration relative to watershed CO2 emission rates due to human activities . Using percent C, soil bulk density, and accretion rates we describe C storage and burial rates. We examine C stable isotope and C/N ratios in the soils to identify dominant sources of C. We hypothesize that accretion and carbon burial rates (CBRs) are greater in more urban watersheds and in more recent decades (1970–2016) compared with earlier decades (1930–1970), attributable to increases in human activities  and alterations associated with rapid urbanization . We discuss how site-specific differences in landscape setting, soil fertility, and flushing patterns may affect C storage and accumulation rates in the mangrove forests.The study aims to elucidate the historic (1930–1970) and recent (1970–2016) decadal mangrove forest C storage and burial rates along an urbanization gradient in the SJBE. Using radiometrically , MPE, SJ, Torr, and Pin with a Russian peat sampler to a maximum depth of 50 cm depending upon ability to penetrate coarse mangrove rhizomes. Core depths ranged from 37–50 cm. One core collected from MPW was damaged during air transport to the United States mainland and was not radiometrically dated. The other nine cores were sliced in one cm increments at the surface (0–3 cm) and then every 2 cm to the bottom of the core (unless otherwise indicated). Soil subsamples were used for radiometric dating, stable isotope, percent C, N, dry bulk density (DBD), and sediment accretion analyses as described below. However, only one of the two replicates from the SJ was processed for DBD due to human error, so DBD values from one SJ core were used in calculations of C storage and burial rates for both replicates from that site.−3) and the other portion was ground to a fine powder using a mortar and pestle. The dried, ground material was used for determining C stable isotopes and percent C. Samples were fumigated prior to analyses with 12 M HCl following the method of 13C = −26.3‰) and USGS 41 (δ13C = 37.63‰) were used to normalize isotopic values of working standards to Vienna Pee Dee Belemnite (δ13C) scales (Soil subsamples were dried at 60°C for at least 48 h. The soils were not sieved so the belowground samples included live and decomposing roots. One portion of the dried soils was used to determine DBD (g cm) scales .3, where X is the less common isotope and R is ratio of the less common to more common isotope (13C/12C). Working standards were analyzed every 24 samples to monitor instrument performance and check data normalization. The precision of the laboratory standards was better than ±0.3‰ for δ13C. The % C and % N were calculated by comparing the peak area of the unknown sample to a standard curve of peak area vs the C or N content of a known standard.Stable isotope values are expressed in δ notation following the formula δX (‰) = [(Rsample/Rstandard) − 1] × 1013C and C/N ratios associated with seagrass, marine algae, particulate organic matter (POM), and mangrove plant matter was based on literature values , and further characterized by dominant species, Red (R. mangle L.), White , and Black [A. germinans (L.) L.] species . Activities of 137Cs and 210Pb were decay corrected to time of collection; suppression of low energy peaks by self-adsorption was corrected according to 210Pb and is based on the same Bayesian chronology statistical treatment as Bacon, a widely used model with 14C ages  and accretion rates, with posterior distributions providing realistic uncertainty estimates. A major benefit of Plum over the commonly used analytical solution to the continuous rate of supply model  estimated within the model framework from the deepest samples. We broadened the priors from default settings within Plum. We simulated means (50%) and the lower (2.5%) and upper confidence limits (97.5%) for each 1 cm depth in the sediment cores. We report means and 95% confidence intervals in the age-depth profiles for each core. Sediment accretion rates (SAR) were obtained from each chronology using the “accrate depth” function in Plum at 1 cm depth intervals. Age-depth models such as these constrain accretion relative to the sediment surface at the time of collection; thus, interpretations of absolute elevation gain within a fixed framework, such as sea level, is not possible without further measurements, such as from sediment elevation tables  for comparative purposes and to inform management efforts assessing anthropogenic impacts and mangrove forest blue carbon value  and historic decades (1930s to 1970s). The historic decades represent a period of mangrove recovery following over a century of intense agricultural activity  in the 1800s , CBRs, C density, and C storage for each time period  overlapped. For C storage comparisons between recent (1970–2016) and historic time periods (1930–1970), values were normalized to account for the difference in range between time periods (46 vs 40 years); however, the statistical differences in C storage results between time periods did not change whether the data were normalized or not.−1 at SJ to 3.76 mm y−1 at Pin in historic decades, and there was no significant difference among sites. Piñones (5.52 mm y−1), MPE (4.91 mm y−1), and Martin PeñaWest (5.47 mm y−1) had similar SAR site means in recent decades, and these were significantly greater than the SARs at La Torrecilla (2.68 mm y−1) and San José (2.02 mm y−1) lagoons . These rates were significantly greater than C burial rates at San José, but not statistically different than La Torrecilla, Piñones, or MPW , but it was not significantly different than soil C storage in La Torrecilla (118.56 Mg ha−1), Piñones (90.50 Mg ha−1), or MPW (72.97 Mg ha−1) (−1). Greater soil C storage in recent decades as compared to historic decades was evident in all SJBE mangrove cores except three lagoonal cores: SJ1, SJ2, and Torr1. Having similar DBD and % C in both historic and recent time periods (Soil C storage ranged from 28.71–55.19 Mg ha forests . In receMg ha−1) . Soil C  periods , resulte periods .−2 y−1; recent: 291.80 g m−2 y−1) had significantly lower MAR than the Caño Martin Peña sites  and Pin  (−3) had significantly higher C density than Piñones (0.024 g cm−3), while in recent decades the MPE (0.096 g cm−3) had significantly greater C density than MPW (0.036 g cm−3). All other sites had similar C densities as the Caño Martin Peña in recent decades  . There wm−2 y−1) . In hist decades .13C ranges making it difficult to separate out specific mangrove species as sources in most cases. The Piñones sediment showed evidence that POM supplemented mangrove plant matter in the soil as the C/N ratios and C isotopes were intermediate between POM and mangrove-derived sources. Among the different mangrove sources, Piñones soil most reflected Black [A. germinans (L.) L.] mangrove  and recent (−25.7‰) decades (13C of SJ (−28.4‰), Torr (−28.2‰), and MPW (−28.8‰) were significantly less enriched than MPE (−27.3‰) and Piñones  and occupied households of 296,589 in the SJBE watershed  plus attributed commercial and industrial electricity use of 2.2 Mg C y−1 . The estuary-wide mangrove forest C sequestration rate (aboveground biomass plus belowground soil: 7.7 Mg C ha−1 y−1) was 20.6% or about one fifth of the watershed anthropogenic emission rates.Anthropogenic emissions were attributed to a population of 769,000 , land development, and human activities  associated with the urbanization of the SJBE in recent decades had direct and indirect effects on soil fertility, hydrology, plant productivity, and sediment deposition. Although there was a distinct urbanization gradient from west to east with the Caño Martin Peña in the west being most urbanized and the Pin the least urbanized, site characteristics such as flushing, landscape setting, and other environmental factors played a role in the C storage and burial rates at the mangrove forest sites. Causes for elevated sediment accretion, C storage, and C accumulation varied among mangrove forest sites in the SJBE.−1 in historic decades and 2.01–5.52 mm y−1 in recent decades. Tide gages at San Juan, PR (NOAA station #9755371) and Magueyes Island, PR (NOAA station #9759110) have long-term sea-level rise trends of 2.09 ± 0.37 mm y−1 (1962–2020) and 1.90 ± 0.30 mm y−1 (1955–2020), indicating mangrove forest accretion rates from the 210Pb age models were at or exceeded long-term sea-level rise rates, although the historic period in this study is not covered fully by the water level records. While the SJBE accretion rates in the historic decades were similar to the global median for mangrove forests  and least urbanized Pin (5.52 mm y−1). Recent SAR and % organic matter at Caño Martin Peña were significantly greater in recent decades compared with historic decades. Such an increase in accretion has been observed in other mangrove forests, coincident with accelerations in sea-level rise , the C burial rates were 58% lower and the C storage 61% lower than the clogged eastern portion (MPE) in recent decades. The site differences in C burial rates and storage between MPW and MPE may be reflective of increased flushing in the MPW in recent times, which might have lowered particulate deposition and C storage. In the eastern clogged end of the Martin Peña, the build-up of autochthonous  and allochthonous C inputs  might have contributed to high SAR and C storage. However, the C stable isotope ratios suggest that refractory mangrove litterfall and roots were the apparent C source in the soils . High emAccretion rates and C storage were also high in the low flushed and least urbanized Pin. The Piñones mangrove soils were acidic, had significantly lower porewater pH (4.7), and higher porewater salinities (62–73 ppt) than the other mangrove sites in the SJBE . Acidic 13C at Piñones, relative to the other SJBE sites. Following the damming of the Río Grande de Loíza in 1953, the Piñones lagoon no longer received water through a series of drainage and navigation canals from the Río Grande de Loíza  at the clogged MPE site likely increased spatial heterogeneity of the mangrove soils . In the 1960s and early 1970s, largescale dredging activities in the northwest inlet connecting Torr with the sea altered the hydrology, distribution and settling of sediment . Indirec−2 y−1 across time periods was similar in magnitude to the global average  was over twice as great as the global soil C burial estimates.Our estimate for the estuary-wide mangrove soil C burial rate of 188 g m−1 for the SJBE. Dividing by the extant mangrove forest  reported by −1 y−1. In the present study (~5 years later), the sum of mangrove aboveground C accumulation (5.2 Mg ha−1 y−1) and belowground C burial (2.5 Mg ha−1 y−1) was 7.7 Mg ha−1 y−, remarkably similar to the −1 was less than half of the 382, 419, and 370 Mg ha−1 averages for other Caribbean mangroves in the United States, Dominican Republic, and Mexico, respectively (−1 (±SD) which was more similar to other Caribbean mangrove forests and the global soil C stock of 283 ± 193 Mg ha−1 (± SD)  .−1) were over 85 times greater than the C sequestered by mangroves . While the amount of C sequestered by mangrove forests in aboveground biomass and soils was less than that emitted by households each year in the watershed, the C sequestration that mangroves provide is an essential ecosystem service. On an annual basis for every 1.2 Mg C sequestered by mangroves, one household’s electricity use can be offset, and it would take an additional 2.2 Mg C to offset the household’s attributed commercial and industrial electricity use. Similarly, 1.85 Mg C sequestered by mangroves can offset one vehicle’s annual emissions. Thus, the amount of C annually sequestered by SJBE mangroves  could offset the annual emissions associated with the electricity usage of around 14,800 households or 9,600 vehicles. If we accounted for commercial and industrial activities in addition to household electricity, then the offset would be about 5,200 households. It is not unusual that the emissions from human activity exceed the annual C sequestration from natural processes, as cities are consumptive entities  were over 85 times greater than the annual SJBE mangrove forest C storage rates . In order to mitigate greenhouse gas emissions in urban, tropical areas, a combination of maintaining healthy mangrove forests, as well as strategies to reduce anthropogenic emissions might be necessary.In most mangrove forest cores spanning the SJBE, greater soil C storage was measured in recent decades (1970–2016) as compared to historic decades (1930–1970), except for two cores from the SJ and one core from Torr. The mangrove sites in the present study had belowground C burial rates ranging from 88 g mSI Zip


To assess in a cross-sectional study the impact of including dental professionals in the multidisciplinary treatment team of head and neck squamous cell carcinoma (HNSCC) patients on the long-term oral health status.Oral health status, dental care behaviours, and oral health–related quality of life were assessed based on a clinical and radiographic examination, interview, and medical records in patients treated for HNSCC ≥ 6 months ago. This patient group (‘cohort 2’) was treated in a multidisciplinary treatment team including dental professionals and compared to a group of HNSCC patients previously treated at the same university, but without dental professionals included in the multidisciplinary treatment team (‘cohort 1’).Cohort 2 consisted of 34 patients, who had received a dental check-up and if necessary, treatment by dental professionals prior to the initiation of cancer treatment. This cohort showed significantly improved oral hygiene habits and a better periodontal health status compared to cohort 1. However, cohort 2 still presented high demand for treatment due to active carious lesions; only a few, statistically insignificant improvements were detected compared to cohort 1.Including dental professionals in the multidisciplinary treatment team of HNSCC patients has a positive impact on patient oral health status—primarily in terms of periodontal disease—6 months and longer after finishing cancer therapy.A team-based approach including dental professionals specialised in head and neck cancer improves oral health status.The online version contains supplementary material available at 10.1007/s00784-021-04276-x. Assessment of dental treatment needs and delivery of treatment after diagnosis and prior to treatment initiation of head and neck squamous cell carcinomas (HNSCC) is considered an integral part in the overall treatment plan –8. EradiIn this context, a previous publication  reportedThe Comprehensive Center Unit  is a newly established department with dental professionals specialised in the treatment of cancer patients. It receives referrals from the nearby hospitals for the assessment of dental treatment needs prior to cancer treatment, as well as for dental treatment support during and after cancer treatment. Patients who 1) were diagnosed with HNSCC ; (2) were fully or partially dentate; (3) > 18 years old; (4) had received a dental check-up  prior to cancer treatment at this specific department; and (5) had finished cancer treatment ≥ 6 months ago were invited to participate (cohort 2). The present cross-sectional study was approved by the ethics committee of the Medical University of Vienna (EK-Nr: 2052/2017) and reporting complies with the STROBE guidelines  age; (2) gender; (3) registered physical address; (4) site of primary tumour; (5) type of cancer treatment ; and (6) time passed since cancer treatment (months). Based on a combination of the medical records and a personal interview, the following information on patient general habits, and dental treatment needs and care behaviours prior to and after cancer treatment was collected: (1) smoking status (never/former/current smoker); (2) alcohol consumption (frequency); (3) socioeconomic status ; (4) education level (no education/school/high school/university); (5) dental treatment performed prior to and after cancer treatment; (6) time passed since last dental check-up; and (7) oral hygiene habits . OHRQoL was assessed by a standardised questionnaire . Similar to previous studies , 26, ansA single examiner (PS) recorded the following clinical parameters at the remaining dentition (including the wisdom teeth): (1) number of teeth; (2) number of teeth with caries; (3) plaque index in %  radiographic alveolar bone loss (ABL) expressed as ‘percentage’ ; (2) number of root canal–treated teeth; (3) number of periapical pathologies  , 30; (4)U test  or by the independent t-test  and chi-squared test was applied for comparison of frequency distributions. In cohort 2, additional comparisons with the same statistical methods were performed between patients continuing with dental treatment at the CCU and those continuing with a general dentist. Any correlations between the OHIP scores and the clinical parameters were assessed by Pearson’s correlation coefficient. Statistical analysis was performed with STATA/IC 16.0 for Mac and a p-value of ≤ 0.05 was considered statistically significant.Data were described descriptively and means (standard deviation), median (first and third quartile), and frequency distributions were calculated; the distribution of the continuous variables was tested by the Shapiro–Wilk test. The data recorded from cohort 2 were compared to the previously published data from cohort 1 ; any difAltogether, 216 patients, who had been treated at some timepoint at the above-mentioned department and potentially fulfilled the eligibility criteria, were contacted, and asked for participation. Except for a single person, all had their physical address in Austria. Specifically, about 79% had their physical address in Vienna, about 15.4% within 50 km to Vienna, 3.7% within 50 to 100 km to Vienna, and only 1.9% more than 100 km away from Vienna. Ninety-three patients could not be reached, 59 denied participating via telephone, 18 were deceased, and 46 were invited for clinical evaluation. However, 12 of those 46 did either not fulfil all eligibility criteria or denied participating in all parts of the examination; hence, 34 patients  could finally be included, constituting cohort 2. At the timepoint of examination, about half of the participants were former smokers and drinking alcohol less than once per month. Furthermore, about two-thirds of the participants were living in a relationship, had finished a basic education, and had a monthly income between 1500 and 3000 €. The only statistically significant difference between the two cohorts was detected for the monthly income, with fewer participants having < 1000 € per month in cohort 2 compared to cohort 1 (Table The oropharynx 41.2%), oral cavity (17.7%), and larynx (17.6%) were the most common sites for HNSCC in cohort 2; although cohort 1 included more patients with HNSCC of the oral cavity, the distribution was not significantly different between the cohorts. In most of the cases (79.4%) a multimodal cancer therapy was performed, which was finished 7–54 months prior to participating; most often a combination of radio- and chemotherapy (50%) or radio- and surgical therapy (23.5%) was applied , yet the average brushing time was longer and the use of any interdental cleaning device more frequent. Specifically, in cohort 2, the average brushing time was almost 1 min longer and only about 23% of the participants did not use any interdental cleaning device, compared to about 60% in cohort 1 . Patients in cohort 2 compared to cohort 1 had a PI about 20% lower (p = 0.003), but the BoP values were significantly worse in cohort 2 compared to cohort 1 (p = 0.005). The clinical and radiographic periodontal parameters were all statistically significantly lower in cohort 2 compared to cohort 1. For example, the mean number of teeth with PD ≥ 5 mm was only 1.4 in cohort 2 compared to 3.1 in cohort 1 and the percentage of patients with ≥ 4 teeth with PD ≥ 5 mm in cohort 2 was only 11.8% compared to 37% in cohort 1 (Table The number of remaining teeth between the 2 cohorts was comparable ( p = 0.00. The clip = 0.123) and only 53 vs. 75% of the patients presented with at least 1 tooth with caries (p = 0.208), respectively. The total number of teeth with caries appeared lower for the patients continuing at the CCU : 1  vs. 4.5 ; p = 0.068). No differences in periodontal status were observed between these 2 subgroups of cohort 2. Furthermore, in regard to the 5 patients having no dental treatment after cancer therapy, all presented with the need of restorative treatment due to carious lesions, and 2 of them presented even a very high number of teeth with active caries lesions (i.e. 15 and 18 teeth).In cohort 2, patients continuing receiving dental treatment at the CCU presented with better oral hygiene and a lower number of caries lesions compared to those that continued with a general dentist. Specifically, the mean PI values were 39.3 vs. 50.3% (p ≥ 0.333). Considering each OHIP question separately, only ‘being totally unable to function because of problems with the teeth, mouth, or dentures’ and BoP showed a statistically significant positive correlation , while the correlation between ‘diet being unsatisfactory because of problems with the teeth, mouth, or dentures’ and the number of teeth with ABL ≥ 33% missed significance .The highest impact on OHRQoL in cohort 2 was noted for feeling uncomfortable to eat food (63.6%) and a worsened sense of taste (52.9%). Furthermore, 47.1% of the respondents indicated that life felt in general less satisfying because of problems with teeth, mouth, or dentures, and that they had a painful feeling in the mouth. Least impact was recorded for having difficulties doing the usual jobs (17.7%) and for being totally unable to function (2.9%) , while patients in the other cohort (cohort 1) were treated for their cancer by a team not including dental professionals and they were only referred to or advised to visit his/her regular  dentist . The resIn particular, almost 60% of the patients in cohort 2 had no teeth with periodontal pockets (i.e. ≥ 5 mm) and only about 12% (i.e. 4 patients) had ≥ 4 teeth i.e. 7–12 teeth) with a PD ≥ 5 mm; in contrast, almost 40% of the patients in cohort 1 had ≥ 4 teeth with PD ≥ 5 mm. This is an important and relevant improvement, especially when considering that poor periodontal status has been repeatedly described to increase the risk for ORN –12 teeth, 31 afteThe patients in cohort 2, similarly to cohort 1  and to wThe relatively small sample size should be considered the major limitation of the present study. Almost half of the patients contacted for participation could not be reached and another fourth denied participating, although almost 80% of them had their registered physical address in Vienna and only about 5% had an address > 50 km away from Vienna. This emphasises the need of more effective HNSCC patient communication about the importance and relevance of continuous long-term follow-up. It also shows the need for implementing novel approaches, such as teledentistry, allowing the provision of continuous care for cancer survivors, independent of the possibility of physical visits. Teledentistry has been shown—especially during the COVID-19 pandemic—as helpful and well-accepted tool for many aspects  . An inteIn conclusion, the present data confirm the general assumption that the inclusion of dental professionals, who are specialised on the treatment of cancer patients, in the multidisciplinary treatment teams of HNSCC patients has a positive impact on oral health status—especially in terms of periodontal disease—6 months and longer after finishing cancer therapy.Supplementary file1 (DOC 83 KB)Supplementary file2 (DOCX 15 KB)Below is the link to the electronic supplementary material.


In contrast, the negative εHf(t) and high δ18O values of the post-Archaean inherited zircons indicate that their parental magma contained recycled older crust due to the enhanced crust-mantle interactions during the evolution of the early continental crust. Therefore, the inherited zircons in the back-arc volcanic rocks not only reflect the evolution of the local magmatism, but they also contain a record of the Archaean crustal fragment and of several global continental amalgamation events.Magmatism has profoundly influenced the evolution of the geosphere, hydrosphere, atmosphere, and biosphere in back-arc basins. However, the timing of the magmatism in the Okinawa Trough (OT) is not well constrained by the age spectra of zircons. Here, for the first time, we carry out an integrated study combining in situ analysis of zircon U–Th–Pb and Hf–O isotopes, and trace element compositions of zircons from the volcanic rocks from the southernmost part of the OT. We found that the young (< 100 ka) zircons in these volcanic rocks have old (108 Ma to 2.7 Ga) inherited cores, which were captured as the magma ascended through the rifting continental crust. In particular, the inherited Archean zircons strongly suggest that remnants of the old East Asian continental blocks underlie the embryonic crustal rifting zone. Moreover, the ages of most of the inherited zircons correspond to five supercontinent amalgamation events. Specifically, the Archaean inherited zircons, which have positive εHf However, the nature of the basement is a controversial issue. Conventional wisdom suggests that the OT basement may be an offshore part of the continental lithosphere of the South China Block, which was related to the northwestward subduction of the Philippine Sea Plate beneath the Eurasian Plate2; In contrast, an allochthonous origin for the OT basement has been proposed by Niu et al.3, that is, it was originally a thinned continental block within the palaeo-Pacific Plate and moved westward with the palaeo-Pacific Plate. However, the lack of basement rock samples has limited our understanding for these issues. The crustal thickness decreases from > 25 km in the northern OT to ~ 10 km on the axis of the SOT graben2. The southernmost part of the OT (SPOT) is considered to be an embryonic crustal rifting zone4, in which the crust (25–30 km) has not experienced significant thinning5 and is characterized by a cluster of active volcanoes dominated by dacites and rhyolites7. These < 0.2 Ma silicic magmas evolved via mixing of a mantle-derived basaltic magma and a crustal felsic magma, followed by extensive fractional crystallization6. Mg element diffusion chronology of the plagioclase in the dacites suggests that relatively long-lived magma storage (at least 600 yrs) occurred in the shallow silicic magma reservoir5. However, the duration of the submarine volcanism in the OT is still poorly constrained. At present, no studies have reported the timing of the magmatism based on age spectra of zircons from the OT volcanic eruptions.The OT, which is located on the western Pacific active continental margin Fig. , is a ba11. Furthermore, inherited zircons in volcanic rocks can provide samples of deeper crustal levels, which makes them a powerful tool for unlocking the mysteries of the Earth’s deep crust15. In this study, we used Quaternary magmatic zircons from the SPOT volcanic rocks and old inherited zircon cores captured from the deep crust during mantle-derived magma ascent through the rifting upper crust to analyze the era of magmatic activity and reveal the nature of the basement rocks in this region, as well as the record of supercontinent amalgamation events.Zircon, which is a common accessory mineral, is a powerful tool for understanding magmatic systems because it often records the protracted history prior to eruptionZircons were separated from the three submarine volcanic rock samples collected at the three stations  ranges  values of − 54.5 to − 6.8, which correspond to εHf(t) values of − 15.7 to + 4.9 and two-stage crustal Hf model ages (TDM2) of 1419–2837 Ma  values of the ~ 2.7 Ga Archaean dark-CL domains are positive  values   Fig. . We inte6  during magma ascent15. Experimental results have demonstrated that the retention times of O isotopes in 20–120 μm zircons at a temperature of 900 °C are between 160 and 5700 years23. For hotter mantle magmas, the time required for the δ18O to reach diffusive equilibrium with the homogeneous mantle value is much shorter than 5.7 ka24. The Zr-undersaturation level of mafic melts causes the fast dissolution of pre-existing zircons under normal conditions25. Thus, it would not be possible for continent-derived zircon crystals that have been recycled back into the mantle by subduction to preserve highly variable O isotope signatures at mantle temperatures24. Therefore, the dark-CL domains with highly variable δ18O values  They lack significant Eu anomalies, exhibit relatively flat HREE patterns  They have oxygen isotope compositions  values  values within the lower crustal range29  They exhibit clear, bright, and broad oscillatory zoning in the CL images and euhedral to subhedral rather than oval shapes Fig. A, indica16.  They lacrns Fig. , suggest16.  They lac16.  They lac16.  They lac30. Similarly, the Archaean inherited zircons (2.7–2.5 Ga) in the studied volcanic rocks suggest the presence of unexposed Archaean lower crust beneath the SPOT  has a very low εHf(t) value (− 15.7) and an Hf model age (TDM2) of 2.6 Ga  and three Mesozoic inherited zircons (150.9–237.5 Ma) exhibit slightly negative εHf(t) values (− 3.3 to − 5.7) and Proterozoic Hf model ages  values and low oxygen isotope values (5.74–5.85‰) , 1.3–0.95 Ga (Rodinia), 0.7–0.5 Ga (Gondwana), and 0.35–0.18 Ga (Pangea)  values of these inherited zircons indicate that their parent magmas contained recycled older crust27. Moreover, the variations in the negative εHf(t) and heterogeneous high oxygen isotope values  Fig. , are uniThe zircon U–Th–Pb ages, trace element compositions, and Hf–O isotopes support the following model for the two silicic magma eruptions in the southwest OT. (1) There were long-lived (at least 100 ka) magma reservoirs beneath the submarine volcanos, indicating that the time of OT rifting is at least 100 ka . (2) The zircon xenocrysts were acquired during the ascent of mantle-derived magma through the overlying crust rather than from recycled subducted sediments. (3) The occurrence of these Archean zircons suggests the presence of unexposed Archean materials in the crust of the southern OT, which have experienced complex modifications related to the addition of juvenile material and the reworking from the Neoarchean onward. (4) The inherited zircons record five supercontinent amalgamation events.The zircons were separated from the three volcanic rock samples Fig. . Represe238U–230Th disequilibrium ages and trace element compositions were obtained using the CAMECA IMS 1270 SIMS at the University of California Los Angeles (UCLA) following the analytical protocols described by Schmitt et al.39 and Bell and Harrison40. Zircon U–Pb and O analyses were performed using the CAMECA IMS 1280 at the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS) following the analytical procedures described by Li et al.41 and Tang et al.42. Finally, Hf isotope analysis was carried out on the zircons using the LA-MC-ICP-MS at Nanjing University, China. The details of the analytical methods and zircon U–Th–Pb–O–Hf isotopic and trace element data are presented in the Supplementary Information.The zircons Supplementary Information.