Engineering artificial photosynthesis based on rhodopsin for CO2 fixation

Microbial rhodopsin, a significant contributor to sustaining life through light harvesting, holds untapped potential for carbon fixation. Here, we construct an artificial photosynthesis system which combines the proton-pumping ability of rhodopsin with an extracellular electron uptake mechanism, establishing a pathway to drive photoelectrosynthetic CO2 fixation by Ralstonia eutropha (also known as Cupriavidus necator) H16, a facultatively chemolithoautotrophic soil bacterium. R. eutropha is engineered to heterologously express an extracellular electron transfer pathway of Shewanella oneidensis MR-1 and Gloeobacter rhodopsin (GR). Employing GR and the outer-membrane conduit MtrCAB from S. oneidensis, extracellular electrons and GR-driven proton motive force are integrated into R. eutropha’s native electron transport chain (ETC). Inspired by natural photosynthesis, the photoelectrochemical system splits water to supply electrons to R. eutropha via the Mtr outer-membrane route. The light-activated proton pump - GR, supported by canthaxanthin as an antenna, powers ATP synthesis and reverses the ETC to regenerate NADH/NADPH, facilitating R. eutropha’s biomass synthesis from CO2. Overexpression of a carbonic anhydrase further enhances CO2 fixation. This artificial photosynthesis system has the potential to advance the development of efficient photosynthesis, redefining our understanding of the ecological role of microbial rhodopsins in nature

Rational design and characterization of nitric oxide biosensors in E. coli Nissle 1917 and Mini SimCells

Nitric oxide (NO) is an important disease biomarker found in many chronic inflammatory diseases and cancers. A well-characterized nitric sensing system is useful to aid the rapid development of bacteria therapy and synthetic biology. In this work, we engineered a set of NO-responsive biosensors based on the PnorV promoter and its NorR regulator in the norRVW operon; the circuits were characterized and optimized in probiotic Escherichia coli Nissle 1917 and mini SimCells (minicells containing designed gene circuits for specific tasks). Interestingly, the expression level of NorR displayed an inverse correlation to the PnorV promoter activation, as a strong expression of the NorR regulator resulted in a low amplitude of NO-inducible gene expression. This could be explained by a competitive binding mechanism where the activated and inactivated NorR competitively bind to the same site on the PnorV promoter. To overcome such issues, the NO induction performance was further improved by making a positive feedback loop that fine-tuned the level of NorR. In addition, by examining two integration host factor (IHF) binding sites of the PnorV promoter, we demonstrated that the deletion of the second IHF site increased the maximum signal output by 25% (500 μM DETA/NO) with no notable increase in the basal expression level. The optimized NO-sensing gene circuit in anucleate mini SimCells exhibited increased robustness against external fluctuation in medium composition. The NO detection limit of the optimized gene circuit pPnorVβ was also improved from 25.6 to 1.3 nM in mini SimCells. Moreover, lyophilized mini SimCells can maintain function for over 2 months. Hence, SimCell-based NO biosensors could be used as safe sensor chassis for synthetic biology

CTQ 839: Candidate for the Smallest Projected Separation Binary Quasar

We report the discovery of the new double quasar CTQ 839. This B = 18.3, radio quiet quasar pair is separated by 2.1" in BRIH filters with magnitude differences of delta m_B = 2.5, delta m_R = delta m_I = 1.9, and delta m_H = 2.3. Spectral observations reveal both components to be z = 2.24 quasars, with relative redshifts that agree at the 100 km/s level, but exhibit pronounced differences in the equivalent widths of related emission features, as well as an enhancement of blue continuum flux in the brighter component longward of the Ly alpha emission feature. In general, similar redshift double quasars can be the result of a physical binary pair, or a single quasar multiply imaged by gravitational lensing. Empirical PSF subtraction of R and H band images of CTQ 839 reveal no indication of a lensing galaxy, and place a detection limit of R = 22.5 and H = 17.4 for a third component in the system. For an Einstein-de Sitter cosmology and SIS model, the R band detection limit constrains the characteristics of any lensing galaxy to z_lens >= 1 with a corresponding luminosity of L >~ 5 L_*, while an analysis based on the redshift probability distribution for the lensing galaxy argues against the existence of a z_lens >~ 1 lens at the 2 sigma level. A similar analysis for a Lambda dominated cosmology, however, does not significantly constrain the existence of any lensing galaxy. The broadband flux differences, spectral dissimilarities, and failure to detect a lensing galaxy make the lensing hypothesis for CTQ 839 unlikely. The similar redshifts of the two components would then argue for a physical quasar binary. At a projected separation of 8.3/h kpc (Omega_matter = 1), CTQ 839 would be the smallest projected separation binary quasar currently known.Comment: Latex, 23 pages including 5 ps figures; accepted for publication in A

Long-term labour market and economic consequences of school exclusions in England:Evidence from two counterfactual approaches

Background: Previous research suggests that school exclusion during childhood is a precursor to social exclusion in adulthood. Past literature on the consequences of school exclusion is, however, scarce and mainly focused on short-term outcomes such as educational attainment, delinquency, and mental health in early adolescence. Moreover, this evidence is based primarily on descriptive and correlational analysis, whereas robust causal evidence is required to best inform policy. Aims: We aimed to estimate the mid-to-long-term impact of school exclusion on labour market and economic outcomes. Sample: The sample included 6,632 young people who at the age of 25/26 in the year 2015 participated in the Next Steps survey of whom 86 were expelled from school and 711 were suspended between the ages of 13/14 and 16/17. Method: Using high quality existing longitudinal data, we utilized four approaches to evaluate the impact of school exclusion: logistic regression-adjustment models, propensity score matching, school fixed-effects analysis, and inverse propensity weighting. The latter two counterfactual approaches were used to estimate causal effects. Results: We found that school exclusion increased the risk of becoming NEET at the age of 19/20, and then remaining economically inactive at the age of 25/26, as well as experiencing higher unemployment risk and earning lower wages also at the age of 25/26. Conclusion: School exclusion has pervasive negative effects into adulthood. Policy interventions should focus on both prevention and mitigating its negative effects. Interventions aimed at re-integrating excluded individuals into education or vocational training could be key in reducing the risk of poor socio-economic outcomes and social exclusion

The impact of school exclusion in childhood on health and well-being outcomes in adulthood:Estimating causal effects using inverse probability of treatment weighting

BackgroundPrevious evidence has suggested a strong association between school exclusion and health outcomes. However, as health risks are themselves related to the risk of experiencing a school exclusion, it has been challenging to determine the extent to which school exclusion impacts later health outcomes, as opposed to reflecting a marker for pre-existing risks.AimThe aim of the current study was to address this challenge in estimating the medium-to-long-term impact of school exclusion of health and well-being outcomes.MethodsTo this end, we used an inverse propensity weighting approach in the Next Steps data set (N = 6534, from wave 1, 2014, to wave 8, 2015).ResultsWe found that after weighting for propensity of treatment scores estimated based on a wide range of factors, including previous health indicators, there was a significant effect of school exclusion on a wide range of health and well-being outcomes.DiscussionThese results provide some of the most robust evidence to date that school exclusion harms long-term health outcomes.ConclusionThe findings suggest that policies should aim to reduce exclusion and ensure access to preventative health support for those who experience a school exclusion

Identification of tidal trapping of microplastics in a temperate salt marsh system using sea surface microlayer sampling

Microplastics are contaminants of increasing global environmental concern. Estuaries are a major transport pathway for land-derived plastics to the open ocean but are relatively understudied compared to coastal and open marine environments. The role of the “estuarine filter”, by which the supply of sediments and contaminants to the sea is moderated by processes including vegetative trapping and particle flocculation, remains poorly defined for microplastics land to sea transfer. Here, we focus on the sea surface microlayer (SML) as a vector for microplastics, and use SML sampling to assess microplastic trapping in a temperate marsh system in Southampton Water, UK. The SML is known to concentrate microplastics relative to the underlying water and is the first part of rising tidal waters to traverse intertidal and upper tidal surfaces. Sampling a salt marsh creek at high temporal resolution allowed assessment of microplastics in-wash and outflow from the salt marsh, and its relationship with tidal state and bulk suspended sediment concentrations (SSC), over spring and neap tides. A statistically significant decrease in microplastics abundance from the flood tide to the ebb tide was found, and a weak positive relationship with SSC observed

New Hubble Space Telescope Observations of Heavy Elements in Four Metal-Poor Stars

Elements heavier than the iron group are found in nearly all halo stars. A substantial number of these elements, key to understanding neutron-capture nucleosynthesis mechanisms, can only be detected in the near-ultraviolet. We report the results of an observing campaign using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope to study the detailed heavy-element abundance patterns in four metal-poor stars. We derive abundances or upper limits from 27 absorption lines of 15 elements produced by neutron-capture reactions, including seven elements (germanium, cadmium, tellurium, lutetium, osmium, platinum, and gold) that can only be detected in the near-ultraviolet. We also examine 202 heavy-element absorption lines in ground-based optical spectra obtained with the Magellan Inamori Kyocera Echelle Spectrograph on the Magellan-Clay Telescope at Las Campanas Observatory and the High Resolution Echelle Spectrometer on the Keck I Telescope on Mauna Kea. We have detected up to 34 elements heavier than zinc. The bulk of the heavy elements in these four stars are produced by r-process nucleosynthesis. These observations affirm earlier results suggesting that the tellurium found in metal-poor halo stars with moderate amounts of r-process material scales with the rare earth and third r-process peak elements. Cadmium often follows the abundances of the neighboring elements palladium and silver. We identify several sources of systematic uncertainty that must be considered when comparing these abundances with theoretical predictions. We also present new isotope shift and hyperfine structure component patterns for Lu II and Pb I lines of astrophysical interest

175 GHz, 400-fs-pulse harmonically mode-locked surface emitting semiconductor laser

We report a harmonically mode-locked vertical external cavity surface emitting laser (VECSEL) producing 400 fs pulses at a repetition frequency of 175 GHz with an average output power of 300 mW. Harmonic mode-locking was established using a 300 µm thick intracavity single crystal diamond heat spreader in thermal contact with the front surface of the gain sample using liquid capillary bonding. The repetition frequency was set by the diamond microcavity and stable harmonic mode locking was achieved when the laser cavity length was tuned so that the laser operated on the 117th harmonic of the fundamental cavity. When an etalon placed intracavity next to the gain sample, but not in thermal contact was used pulse groups were observed. These contained 300 fs pulses with a spacing of 5.9 ps. We conclude that to achieve stable harmonic mode locking at repetition frequencies in the 100s of GHz range in a VECSEL there is a threshold pulse energy above which harmonic mode locking is achieved and below which groups of pulses are observed

Effects of a demand-led evidence briefing service on the uptake and use of research evidence by commissioners of health services:A controlled before-and-after study

Background: The Health and Social Care Act 2012 has mandated research use as a core consideration of health service commissioning arrangements. We evaluated whether or not access to a demand-led evidence briefing service improved use of research evidence by commissioners compared with less intensive and less targeted alternatives. Design: Controlled before-and-after study. Setting: Clinical Commissioning Groups (CCGs) in the north of England. Main outcome measures: Change at 12 months from baseline of a CCG’s ability to acquire, assess, adapt and apply research evidence to support decision-making. Secondary outcomes measured individual clinical leads’ and managers’ intentions to use research evidence in decision-making. Methods: Nine CCGs received one of three interventions: (1) access to an evidence briefing service; (2) contact plus an unsolicited push of non-tailored evidence; or (3) an unsolicited push of non-tailored evidence. Data for the primary outcome measure were collected at baseline and 12 months post intervention, using a survey instrument devised to assess an organisation’s ability to acquire, assess, adapt and apply research evidence to support decision-making. In addition, documentary and observational evidence of the use of the outputs of the service was sought and interviews with CCG participants were undertaken. Results: Most of the requests were conceptual; they were not directly linked to discrete decisions or actions but intended to provide knowledge about possible options for future actions. Symbolic use to justify existing decisions and actions were less frequent and included a decision to close a walk-in centre and to lend weight to a major initiative to promote self-care already under way. The opportunity to impact directly on decision-making processes was limited to work to establish disinvestment policies. In terms of impact overall, the evidence briefing service was not associated with increases in CCGs’ capacity to acquire, assess, adapt and apply research evidence to support decision-making, individual intentions to use research findings or perceptions of CCGs’ relationships with researchers. Regardless of the intervention received, at baseline participating CCGs indicated that it felt it was inconsistent in its research-seeking behaviours and its capacity to acquire research remained so at follow-up. The informal nature of decision-making processes meant that there was little or no traceability of the use of evidence. Limitations: Low baseline and follow-up response rates (of 68% and 44%, respectively) and missing data limit the reliability of these findings. Conclusions: Access to a demand-led evidence briefing service did not improve the uptake and use of research evidence by NHS commissioners compared with less intensive and less targeted alternatives. Commissioners appear to be well intentioned but ad hoc users of research. Future work: Further research is required on the effects of interventions and strategies to build individual and organisational capacity to use research. Resource-intensive approaches to providing evidence may best be employed to support instrumental decision-making. Comparative evaluation of the impact of less intensive but targeted strategies on the uptake and use of research by commissioners is warranted. Funding: National Institute for Health Research Health Services and Delivery Research programme