638 research outputs found
Using Parahydrogen to Hyperpolarize Amines, Amides, Carboxylic Acids, Alcohols, Phosphates and Carbonates
Hyperpolarization turns weak NMR and MRI responses into strong signals so normally impractical measurements are possible. We use parahydrogen here to rapidly hyperpolarize appropriate 1H, 13C, 15N and 31P responses of analytes such as NH3 and important amines such as phenylethylamine, amides such as acetamide, urea and methacrylamide, alcohols spanning methanol through octanol and glucose, the sodium salts of carboxylic acids such as acetic acid and pyruvic acid, sodium phosphate, disodium adenosine 5’triphosphate and sodium hydrogen carbonate. The associated signal gains are used to demonstrate it is possible to collect informative single-shot NMR spectra of these analytes in seconds at the micromole level in a 9.4 T observation field. To achieve these wide ranging signal gains, we first employ the Signal Amplification By Reversible Exchange (SABRE) process to hyperpolarize an amine or ammonia and then employ their exchangeable NH protons to relay polarization into the analyte without changing its identity. We found the 1H signal gains reach as high as 650-fold per proton, while for 13C, the corresponding signal gains achieved in a 1H-13C refocused INEPT experiment exceed 570-fold and those in a direct detected 13C measurement 400-fold. Thirty one examples are described to demonstrate the applicability of this technique
On the impact of transport model errors for the estimation of CO2 surface fluxes from GOSAT observations
A series of observing system simulation experiments is presented in which column averaged dry air mole fractions of CO2 (XCO2) from the Greenhouse gases Observing SATellite (GOSAT) are made consistent or not with the transport model embedded in a flux inversion system. The GOSAT observations improve the random errors of the surface carbon budget despite the inconsistency. However, we find biases in the inferred surface CO2 budget of a few hundred MtC/a at the subcontinental scale, that are caused by differences of only a few tenths of a ppm between the simulations of the individual XCO2 soundings. The accuracy and precision of the inverted fluxes are little sensitive to an 8-fold reduction in the data density. This issue is critical for any future satellite constellation to monitor XCO2 and should be pragmatically addressed by explicitly accounting for transport errors in flux inversion systems
Bronze Age and Early Saxon activity at Dagenham Heathway, London Borough of Barking and Dagenham
Excavations by Pre-Construct Archaeology Ltd in
advance of development of a former school playing
field at Dagenham Heathway, in the London Borough
of Barking and Dagenham, revealed prehistoric
archaeology, dominated by two phases of Late Bronze
Age activity. This comprised a series of ditched fields
with possible stock management elements, which was
superseded by an enclosed settlement containing three
roundhouses. The site was not reoccupied again
until the Early Saxon period, when a different type of
agrarian settlement was established. During either the
Middle or Late Saxon period the site was abandoned
and another series of field ditches was laid out
Signal Amplification by Reversible Exchange (SABRE): : From Discovery to Diagnosis
Signal Amplification by Reversible Exchange (SABRE) turns typically weak magnetic resonance responses into strong signals making previously impractical measurements possible. This technique has gained significant popularity due to its speed and simplicity. This minireview tracks the development of SABRE from the initial hyperpolarization of pyridine in 2009, to the point where 50% 1H polarization levels have be achieved in a di-deuterio-nicotinate, a key step in the pathway to potential clinical use. Simple routes to highly efficient 15N hyperpolarization and the creation of hyperpolarized long-lived magnetic states are illustrated. It finishes by describing how the recently reported SABRE-RELAY approach offers a route for parahydrogen to hyperpolarize a much wider array of molecular scaffolds, such as amides, alcohols, carboxylic acids and phosphates, than was previously thought possible. We predict that collectively these developments ensure that SABRE will significantly impact on both chemical analysis and the diagnosis of disease in the future
Erratum: Causal Knowledge Promotes Behavioral Self-Regulation: An Example using Climate Change Dynamics (PLoS ONE (2017) 12:9 (E0184480) DOI: 10.1371/Journal.pone.0184480)
In the Task overview: Managing a dynamic human-climate system subsection of the Introduction, there is an error in equation 4. There is a factor of τ that is missing from the denominator of the first term that appears on the right-hand side of the equation. Please view the complete, correct equation here [Formula Presented]
Can nutrient profiling help to identify foods which diet variety should be encouraged? Results from the Whitehall II cohort
Higher variety of recommended foods, identified arbitrarily based on dietary guidelines, has been associated with better health status. Nutrient profiling is designed to identify objectively, based on nutrient content, healthier foods whose consumption should be encouraged. The objective was to assess the prospective associations between total food variety (food variety score, FVS) and variety from selected recommended and non-recommended foods (RFV and NRFV, respectively) and risk of chronic disease and mortality. In 1991–3, 7251 participants of the Whitehall II study completed a 127-item FFQ. The FVS was defined as the number of foods consumed more than once a week. (N)RFV(Ofcom) and (N)RFV(SAIN,LIM) were similarly derived selecting healthier (or less healthier) foods as defined by the UK Ofcom and French SAIN,LIM nutrient profile models, respectively. Multi-adjusted Cox regressions were fitted with incident CHD, diabetes, CVD, cancer and all-cause mortality (318, 754, 137, 251 and 524 events, respectively – median follow-up time 17 years). RFV and NRFV scores were mutually adjusted. The FVS (fourth v. first quartile) was associated with a 39 and 26 % reduction of prospective CHD and all-cause mortality risk, respectively. The RFV(Ofcom) (third v. first quartile) was associated with a 27 and 35 % reduction of all-cause mortality and cancer mortality risk, respectively; similar associations were suggested, but not significant for the RFV(SAIN,LIM). No prospective associations were observed with NRFV scores. The results strengthen the rationale to promote total food variety and variety from healthy foods. Nutrient profiling can help in identifying those foods whose consumption should be encouraged
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