Rapid extraction of dissolved inorganic carbon from seawater and groundwater samples for radiocarbon dating

© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Limnology and Oceanography: Methods 14 (2016): 24-30, doi:10.1002/lom3.10066.We designed and developed a system to efficiently extract dissolved inorganic carbon (DIC) from seawater and groundwater samples for radiocarbon dating. The Rapid Extraction of Dissolved Inorganic Carbon System (REDICS) utilizes a gas-permeable polymer membrane contactor to extract the DIC from an acidified water sample in the form of carbon dioxide (CO2), introduce it to a helium gas stream, cryogenically isolate it, and store it for stable and radiocarbon isotope analysis. The REDICS system offers multiple advantages to the DIC extraction method which has been used for the last several decades at the National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS) at the Woods Hole Oceanographic Institution, including faster DIC extraction, streamlined analysis, and minimized set-up and prep time. The system was tested using sodium carbonate and seawater standards, duplicates of which were also processed on the water stripping line (WSL) at NOSAMS. The results demonstrate that the system successfully extracts, quantifies, and stores more than 99% of the DIC in less than 20 min. Stable and radiocarbon isotope analysis demonstrated system precision of 0.04‰ and 7.8‰, respectively. A Sargasso Sea depth profile was used to further validate the system. The results show high precision for both stable and radiocarbon analysis with pooled standard deviations of 0.02‰ and 5.6‰, respectively. A comparison between the REDICS and WSL analyses indicates a good accuracy for both stable and radio-isotope analysis.NSF Cooperative Agreements for the Operation of a National Ocean Sciences Accelerator Mass Spectrometry Facility (OCE-0753487 and OCE-123966) supported this research

Carbon isotopic evidence for microbial control of carbon supply to Orca Basin at the seawater–brine interface

© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeosciences 10 (2013): 3175-3183, doi:10.5194/bg-10-3175-2013.Orca Basin, an intraslope basin on the Texas-Louisiana continental slope, hosts a hypersaline, anoxic brine in its lowermost 200 m in which limited microbial activity has been reported. This brine contains a large reservoir of reduced and aged carbon, and appears to be stable at decadal time scales: concentrations and isotopic composition of dissolved inorganic (DIC) and organic carbon (DOC) are similar to measurements made in the 1970s. Both DIC and DOC are more "aged" within the brine pool than in overlying water, and the isotopic contrast between brine carbon and seawater carbon is much greater for DIC than DOC. While the stable carbon isotopic composition of brine DIC points towards a combination of methane and organic carbon remineralization as its source, radiocarbon and box model results point to the brine interface as the major source region for DIC, allowing for only limited oxidation of methane diffusing upwards from sediments. This conclusion is consistent with previous studies that identify the seawater–brine interface as the focus of microbial activity associated with Orca Basin brine. Isotopic similarities between DIC and DOC suggest a different relationship between these two carbon reservoirs than is typically observed in deep ocean basins. Radiocarbon values implicate the seawater–brine interface region as the likely source region for DOC to the brine as well as DIC.This work was funded by the WHOI Postdoctoral Scholar program, NSF Cooperative Agreement for the Operation of a National Ocean Sciences Accelerator Mass Spectrometry Facility (OCE-0753487), and the US National Science Foundation’s Emerging Frontiers program (award 0801741 to SBJ)

Ultra-small graphitization reactors for ultra-microscale 14C analysis at the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) Facility

© The Arizona Board of Regents on behalf of the University of Arizona, 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Radiocarbon 57, no. 1 (2015): 109–122, doi:10.2458/azu_rc.57.18118.In response to the increasing demand for 14C analysis of samples containing less than 25 µg C, ultra-small graphitization reactors with an internal volume of ~0.8 mL were developed at NOSAMS. For samples containing 6 to 25 µg C, these reactors convert CO2 to graphitic carbon in approximately 30 min. Although we continue to refine reaction conditions to improve yield, the reactors produce graphite targets that are successfully measured by AMS. Graphite targets produced with the ultra-small reactors are measured by using the Cs sputter source on the CFAMS instrument at NOSAMS where beam current was proportional to sample mass. We investigated the contribution of blank carbon from the ultra-small reactors and estimate it to be 0.3 ± 0.1 µg C with an Fm value of 0.43 ± 0.3. We also describe equations for blank correction and propagation of error associated with this correction. With a few exceptions for samples in the range of 6 to 7 µg C, we show that corrected Fm values agree with expected Fm values within uncertainty for samples containing 6–100 µg C.This work was funded by the NSF Cooperative Agreement for the Operation of a National Ocean Sciences Accelerator Mass Spectrometry Facility (OCE-0753487). S R Shah Walter was also partially supported by the WHOI Postdoctoral Scholar Program

Multiple carbon incorporation strategies support microbial survival in cold subseafloor crustal fluids

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Trembath-Reichert, E., Shah Walter, S. R., Ortiz, M. A. F., Carter, P. D., Girguis, P. R., & Huber, J. A. Multiple carbon incorporation strategies support microbial survival in cold subseafloor crustal fluids. Science Advances, 7(18), (2021): eabg0153, https://doi.org/10.1126/sciadv.abg0153.Biogeochemical processes occurring in fluids that permeate oceanic crust make measurable contributions to the marine carbon cycle, but quantitative assessments of microbial impacts on this vast, subsurface carbon pool are lacking. We provide bulk and single-cell estimates of microbial biomass production from carbon and nitrogen substrates in cool, oxic basement fluids from the western flank of the Mid-Atlantic Ridge. The wide range in carbon and nitrogen incorporation rates indicates a microbial community well poised for dynamic conditions, potentially anabolizing carbon and nitrogen at rates ranging from those observed in subsurface sediments to those found in on-axis hydrothermal vent environments. Bicarbonate incorporation rates were highest where fluids are most isolated from recharging bottom seawater, suggesting that anabolism of inorganic carbon may be a potential strategy for supplementing the ancient and recalcitrant dissolved organic carbon that is prevalent in the globally distributed subseafloor crustal environment.The Gordon and Betty Moore Foundation sponsored most of the observatory components at North Pond through grant GBMF1609. This work was supported by the National Science Foundation through grants NSF OCE-1745589, OCE-1635208, and OCE-1062006 to J.A.H. and NSF OCE-1635365 to P.R.G. and S.R.S.W.; NASA Postdoctoral Fellowship with the NASA Astrobiology Institute to E.T.-R.; L’Oréal USA For Women in Science Fellowship to E.T.-R.; and Woods Hole Partnership Education Program, sponsored by the Woods Hole Diversity Initiative to M.A.F.O. The Center for Dark Energy Biosphere Investigations (C-DEBI OCE-0939564) also supported the participation of J.A.H. and P.D.C. This is C-DEBI contribution number 564

New Constraints on Methane Fluxes and Rates of Anaerobic Methane Oxidation in a Gulf of Mexico Brine Pool via In Situ Mass Spectrometry

Deep-sea biogeochemical cycles are, in general, poorly understood owing to the difficulties of making measurements in situ, recovering samples with minimal perturbation, and, in many cases, coping with high spatial and temporal heterogeneity. In particular, biogeochemical fluxes of volatiles such as methane remain largely unconstrained because of the difficulties with accurate quantification in situ and the patchiness of point sources such as seeps and brine pools. To better constrain biogeochemical fluxes and cycling, we have developed a deep-sea in situ mass spectrometer (ISMS) to enable high-resolution quantification of volatiles in situ. Here we report direct measurements of methane concentrations made in a Gulf of Mexico brine pool located at a depth of over 2300 m. Concentrations of up to 33 mM methane were observed within the brine pool, whereas concentrations in the water directly above were three orders of magnitude lower. These direct measurements enabled us to make the first accurate estimates of the diffusive flux from a brine pool, calculated to be $1.1\pm0.2 mol m^{-2} yr^{-1}$. Integrated rate measurements of aerobic methane oxidation in the water column overlying the brine pool were $~320 \mu mol m^{-2} yr^{-1}$, accounting at most for just 0.03% of the diffusive methane flux from the brine pool. Calculated rates of anaerobic methane oxidation were $600-1200 \mu M yr^{-1}$, one to two orders of magnitude higher than previously published values of AOM in anoxic fluids. These findings suggest that brine pools are enormous point sources of methane in the deep sea, and may, in aggregate, have a pronounced impact on the global marine methane cycle.Organismic and Evolutionary Biolog

Drug utilization study in a neonatal intensive care unit of a government tertiary care hospital in Western Maharashtra

Background: Presently drug utilization studies (DUS) are in an evolving era. Current literature search has shown paucity of epidemiological studies in the field of paediatric pharmacology. Hence the present study was designed to assess the drug utilization pattern in neonatal intensive care unit to improvise the current prescription practices, if required and to determine areas in neonatal pharmacology in need of further research.Methods: A prospective, observational study spanned for a period of one year from January 2015 to December 2015 was conducted at the neonatal intensive care unit (NICU), Government teaching tertiary care hospital, Maharashtra. Data of prescribed drugs was collected. WHO prescribing indicators were used for evaluating DUS. Assessment of exposure rates of different class of drugs in different gestational age groups was done. Data were analysed using descriptive studies.Results: Data of 205 neonates, showed male preponderance (53.17%) over female neonates (46.83%). With regard to the gestational age, 47.31% were term, 52.68% preterm. Average number of drugs per encounter was 6.69. 76.29% drugs were prescribed by generic name and 69.80 % drugs were from IAP list of essential medicines for children. Mean drug use was 6.23±3.34 per patient. Most common class of drug to which neonates were exposed was antibiotics (96.10%) and amikacin topped the list with exposure rate of 91.22%.Conclusions: The present study substantiates the need for implementation of institutional antibiotic policies, awareness regarding IAP list of essential drugs for children, prescription by generic name and rational drug use

Serum lipid profile in non-polycystic ovary syndrome and polycystic ovary syndrome women: a comparative and correlational study

Background: Polycystic ovary syndrome (PCOS), in addition to impaired ovulation, also affects metabolic pathways. Dyslipidemia, occurring in PCOS women leads to cardiovascular diseases in them. The purpose of the present study was to compare lipid profile and its correlation with biochemical and hormonal parameters in PCOS and non PCOS women, to analyse the correlation of lipid profile with hirsutism and body mass index (BMI) in PCOS women.Methods: The present study includes 68 women divided into non PCOS groups (n=30) and PCOS (n=38) as defined by Rotterdam criteria. PCOS group further divided into overweight / obese (n=23) and normal weight subgroups (n=15). Lipid profile, fasting blood glucose and hormonal profile were done in all the groups.Results: TG and TC/HDL ratio were significantly high in PCOS group. Hirsute patients had raised LDL levels as compared to non-hirsute. LDL showed positive significant correlation with insulin, HOMA, testosterone in PCOS group. TC was significantly positively correlated with insulin and HOMA in PCOS group. In both normal weight and overweight / obese PCOS subgroups, LDL had positive and significant correlation with testosterone. TC showed positive and significant correlation with HOMA in overweight/obese subgroup. HDL showed positive and highly significant correlation with FSH in normal weight PCOS.Conclusions: Hyperandrogenism in PCOS may be additionally marked by raised LDL. Overweight/obese PCOS subgroup may be prone to dyslipidemia as well as deranged glucose homeostasis, thereby making it an important therapeutic target

Autonomous Application of Quantitative PCR in the Deep Sea: In Situ Surveys of Aerobic Methanotrophs Using the Deep-Sea Environmental Sample Processor

Recent advances in ocean observing systems and genomic technologies have led to the development of the deep-sea environmental sample processor (D-ESP). The DESP filters particulates from seawater at depths up to 4000 m and applies a variety of molecular assays to the particulates, including quantitative PCR (qPCR), to identify particular organisms and genes in situ. Preserved samples enable laboratory-based validation of in situ results and expanded studies of genomic diversity and gene expression. Tests of the D-ESP at a methane-rich mound in the Santa Monica Basin centered on detection of 16S rRNA and particulate methane monooxygenase (pmoA) genes for two putative aerobic methanotrophs. Comparison of in situ qPCR results with laboratory-based assays of preserved samples demonstrates the D-ESP generated high-quality qPCR data while operating autonomously on the seafloor. Levels of 16S rRNA and pmoA cDNA detected in preserved samples are consistent with an active community of aerobic methanotrophs near the methane-rich mound. These findings are substantiated at low methane sites off Point Conception and in Monterey Bay where target genes are at or below detection limits. Successful deployment of the D-ESP is a major step toward developing autonomous systems to facilitate a wide range of marine microbiological investigations

Standardizing Clinical Trials Workflow Representation in UML for International Site Comparison

BACKGROUND: With the globalization of clinical trials, a growing emphasis has been placed on the standardization of the workflow in order to ensure the reproducibility and reliability of the overall trial. Despite the importance of workflow evaluation, to our knowledge no previous studies have attempted to adapt existing modeling languages to standardize the representation of clinical trials. Unified Modeling Language (UML) is a computational language that can be used to model operational workflow, and a UML profile can be developed to standardize UML models within a given domain. This paper's objective is to develop a UML profile to extend the UML Activity Diagram schema into the clinical trials domain, defining a standard representation for clinical trial workflow diagrams in UML. METHODS: Two Brazilian clinical trial sites in rheumatology and oncology were examined to model their workflow and collect time-motion data. UML modeling was conducted in Eclipse, and a UML profile was developed to incorporate information used in discrete event simulation software. RESULTS: Ethnographic observation revealed bottlenecks in workflow: these included tasks requiring full commitment of CRCs, transferring notes from paper to computers, deviations from standard operating procedures, and conflicts between different IT systems. Time-motion analysis revealed that nurses' activities took up the most time in the workflow and contained a high frequency of shorter duration activities. Administrative assistants performed more activities near the beginning and end of the workflow. Overall, clinical trial tasks had a greater frequency than clinic routines or other general activities. CONCLUSIONS: This paper describes a method for modeling clinical trial workflow in UML and standardizing these workflow diagrams through a UML profile. In the increasingly global environment of clinical trials, the standardization of workflow modeling is a necessary precursor to conducting a comparative analysis of international clinical trials workflows

Origins of archaeal tetraether lipids in sediments : insights from radiocarbon analysis

Author Posting. © Elsevier B.V., 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 72 (2008): 4577-4594, doi:10.1016/j.gca.2008.06.021.Understanding the supply and preservation of glycerol dibiphytanyl glycerol tetraethers (GDGTs) in marine sediments helps inform their use in paleoceanography. Compound-specific radiocarbon measurements of sedimentary alkenones from multiple environments have been used to gain insight into processes that affect paleo-temperature reconstructions. Similar analyses are warranted to investigate how analogous processes affecting GDGTs impact TEX86 paleotemperatures. Here we present radiocarbon measurements on individual GDGTs from Bermuda Rise and Santa Monica Basin sediments and discuss the results in the context of previous studies of co-depositional alkenones and foraminifera. The 149 C contents of GDGTs and planktonic foraminifera in Bermuda Rise are very similar, suggesting a local source; and TEX86- derived temperatures agree more closely with foraminiferal temperatures than do temperatures. In contrast, GDGTs in Santa Monica Basin are depleted in 1412 C relative to both alkenones and foraminifera, and TEX86 temperatures agree poorly with known surface water values. We propose three possible factors that could explain these results: (i) GDGTs may be labile relative to alkenones during advective transport through oxic waters; (ii) archaeal production deep in the water column may contribute 1416 C-depleted GDGTs to sediments; and (iii) some GDGTs also may derive from sedimentary archaeal communities. Each of these three processes is likely to occur with varying relative importance depending on geographic location. The latter two may help to explain why TEX86 temperature reconstructions from Santa Monica Basin do not appear to reflect actual sea surface temperatures. Terrigenous GDGTs are unlikely to be major contributors to Bermuda Rise or Santa Monica Basin sediments, based on values of the BIT index. The results also indicate that the crenarchaeol regioisomer is governed by processes different from other GDGTs. Individual measurements of the crenarchaeol regioisomer are significantly depleted in 1424 C relative to co-occurring GDGTs, indicating an alternative origin for this compound that presently remains unknown. Re-examination of the contribution of crenarchaeol regioisomer to the TEX86 index shows that it is a significant influence on the sensitivity of temperature reconstructions.This work was supported by the David & Lucille Packard Foundation and by NSF-OCE-0241363 and EAR-0311937 (to A.P.)