scholarly journals Distribution of Methane Plumes on Cascadia Margin and Implications for the Landward Limit of Methane Hydrate Stability

2021 ◽  
Vol 9 ◽  
Author(s):  
Susan G. Merle ◽  
Robert W. Embley ◽  
H. Paul Johnson ◽  
T.-K. Lau ◽  
Benjamin J. Phrampus ◽  
...  

Nearly 3,500 methane bubble streams, clustered into more than 1,300 methane emission sites, have been identified along the US Cascadia margin, derived both from archived published data and 2011, 2016–2018 dedicated multibeam surveys using co-registered seafloor and water column data. In this study, new multibeam sonar surveys systematically mapped nearly 40% of the US Cascadia margin, extending from the Strait of Juan de Fuca in the north to the Mendocino fracture zone in the south, and bounded East–West by the coast and the base of the accretionary prism. The frequency-depth histogram of the bubble emission sites has a dominant peak at the 500 m isobar, which extends laterally along much of the Cascadia margin off Oregon and Washington. Comparisons with published seismic data on the distribution of bottom simulating reflectors (BSR), which is the acoustic impedance boundary between methane hydrate (solid phase) and free gas phase below, correlates the bottom simulating reflectors upward termination of the feather edge of methane hydrate stability (FEMHS) zone and the newly identified bubble emission sites off Oregon and Washington. The Cascadia margin off northern California, where the BSR ends seaward of the FEMHS, has fewer sites centered on the 500 m isobaths, although data are more limited there. We propose that the peak in bubble emission sites observed near the 500 m isobath results from migration of free gas from beneath the solid phase of the BSR upslope to the FEMHS termination zone, and suggest that this boundary will be useful to monitor for a change in methane release rate potentially related to a warming ocean.

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 590
Author(s):  
Lihua Wan ◽  
Xiaoya Zang ◽  
Juan Fu ◽  
Xuebing Zhou ◽  
Jingsheng Lu ◽  
...  

The large amounts of natural gas in a dense solid phase stored in the confined environment of porous materials have become a new, potential method for storing and transporting natural gas. However, there is no experimental evidence to accurately determine the phase state of water during nanoscale gas hydrate dissociation. The results on the dissociation behavior of methane hydrates confined in a nanosilica gel and the contained water phase state during hydrate dissociation at temperatures below the ice point and under atmospheric pressure are presented. Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffraction (PXRD) were used to trace the dissociation of confined methane hydrate synthesized from pore water confined inside the nanosilica gel. The characterization of the confined methane hydrate was also analyzed by PXRD. It was found that the confined methane hydrates dissociated into ultra viscous low-density liquid water (LDL) and methane gas. The results showed that the mechanism of confined methane hydrate dissociation at temperatures below the ice point depended on the phase state of water during hydrate dissociation.


2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 275.2-276
Author(s):  
N. Fukui ◽  
P. G. Conaghan ◽  
K. Togo ◽  
N. Ebata ◽  
L. Abraham ◽  
...  

Background:Patients with knee osteoarthritis (OA) who do not achieve adequate pain relief and functional improvement with a combination of non-pharmacologic and pharmacologic therapies are recommended an arthroplasty as an effective option to relieve severe pain and functional limitations. However, some patients are reluctant to undergo surgical interventions, and clinicians may choose to avoid or delay surgery due to safety risks and/or the financial cost. It is of interest to understand if the use and perception of surgery differs between countries, however, few published data exist.Objectives:To demonstrate how surgery and the use of surgical procedures differs across Japan, United States of America (US) and 5 major European countries (EU5) and to evaluate patient perception towards surgery.Methods:Data were drawn from the Adelphi OA Disease Specific Programme (2017-18), a point-in-time survey of primary care physicians (PCP), rheumatologists (rheums), orthopaedic surgeons (orthos) and their OA patients. Patients with physician-diagnosed knee OA were included and segmented into two categories: had previous surgery (PS) and never had surgery (NS). A Fisher’s exact test was performed on the two groups. Physicians reported on patient demographics; whether patients had undergone surgery; type of surgery; success of surgery; how success was defined; and reasons for wanting to delay surgery. Patients reported their willingness to undergo surgery; reasons for not wanting surgery; how successful their surgery was; and how they defined this success.Results:Physician/patient reported data were available for 302,230 (Japan), 527,283 (US) and 1487,726 (EU5) patients with diagnosed knee OA. Patients were categorised by their physicians as mild (40% Japan; 34% US; 24% EU5), moderate (49% Japan; 49% US; 56% EU5) or severe (9% Japan; 17% US; 19% EU5). Patients in Japan were more likely to be female (78% vs 54% US; 58% EU5), older (73 vs 65 US; 66 EU5) and have a lower BMI than patients in the US and EU5. Obesity and diabetes were much less prevalent among patients in Japan. One in ten patients in Japan had undergone a surgery (10%), far fewer than in the US (22%) or EU5 (17%). When surgery was performed, this was more likely to be a total joint replacement (TJR) in Japan, whereas in the EU and US, arthroscopic washout was more commonly performed.For over half of Japanese patients (56%), successful surgery was more likely to be defined as having no more pain (vs. 35% US; 14% EU5). Improved mobility and a reduction in pain were also commonly reported reasons. Physicians (in each region) were more likely to suggest pain reduction, rather than no pain, and improved mobility as markers of success. Patients in Japan were much more likely to say they would not agree to surgery if recommended by their doctor, or were unsure (84% vs. 68% US; 62% EU5). The main reason for patient reluctance in Japan was fear of surgery, whereas in the US and EU5 the main reason given was that surgery was not needed. This finding was also evident among physicians in Japan, who frequently reported that patient reluctance was a key reason for delaying surgery. Physicians in Japan, do however, report that patient request was one of their main triggers for recommending surgery (45% vs 20% US; 16% EU5).Conclusion:Although surgery can be an effective option for those with OA who have exhausted other treatment options, some patients are reluctant to undergo surgery out of fear, especially in Japan, possibly due to the higher patient age. Physicians aiming to delay surgery were driven by patient reluctance in Japan, whereas cost to patient was a bigger factor in the US and EU5. The higher level of TJR vs. other surgery options among patients in Japan may suggest physicians are looking for higher levels of efficacy.Disclosure of Interests:Naoshi Fukui Speakers bureau: Pfizer, Consultant of: Pfizer, Philip G Conaghan Speakers bureau: Abbvie, Novartis, Consultant of: AstraZeneca, BMS, Eli Lilly, EMD Serono, Flexion Therapeutics, Galapagos, Gilead, Novartis, Pfizer, Kanae Togo Shareholder of: Pfizer, Employee of: Pfizer, Nozomi Ebata Shareholder of: Pfizer, Employee of: Pfizer, Lucy Abraham Shareholder of: Pfizer, Employee of: Pfizer, James Jackson: None declared, Jessica Jackson: None declared, Mia Berry: None declared, Hemant Pandit Paid instructor for: Bristol Myers Squibb, Consultant of: Johnson and Johnson, Grant/research support from: GSK


2021 ◽  
Vol 413 (11) ◽  
pp. 3093-3105
Author(s):  
Mateusz Kacper Woźniak ◽  
Laura Banaszkiewicz ◽  
Justyna Aszyk ◽  
Marek Wiergowski ◽  
Iwona Jańczewska ◽  
...  

AbstractAlcohol consumption during pregnancy constitutes one of the leading preventable causes of birth defects and neurodevelopmental disorders in the exposed children. Fatty acid ethyl esters (FAEEs), ethyl glucuronide (EtG) and ethyl sulfate (EtS) have been studied as potential biomarkers of alcohol consumption. However, most analytical approaches proposed for their analysis in meconium samples consist of separated extraction procedures requiring the use of two meconium aliquots, which is costly in terms of both time and materials. Therefore, the aim of this study was to develop and validate a method for the simultaneous extraction of 9 FAEEs, EtG and EtS from one meconium aliquot. The sample was homogenized using methanol, and then FAEEs were extracted with hexane while EtG and EtS were isolated using acetonitrile. Then, extracts were applied to solid-phase extraction columns and analysed by gas chromatography mass spectrometry (FAEEs) and liquid chromatography tandem mass spectrometry (EtG and EtS). Calibration curves were linear with r values greater than 0.99. The LODs ranged from 0.8 to 7.5 ng/g for FAEEs and were 0.2 ng/g and 0.8 ng/g for EtS and EtG, respectively. LOQs ranged from 5 to 25 ng/g for FAEEs and were 1 ng/g and 2.5 ng/g for EtS and EtG, respectively. Accuracies and precisions were between 93.8 and 107% and between 3.5 and 9.7%, respectively. The recovery values ranged from 89.1 to 109%. The method proved to be sensitive, specific, simple and fast and allowed for the reduction of the amount of organic solvent used for extraction compared to other published data while higher recoveries were obtained. The method was used for analysis of meconium samples in two cases of mothers who were consuming alcohol during pregnancy.


2016 ◽  
Vol 124 (5) ◽  
pp. 1524-1530 ◽  
Author(s):  
Timothy R. Smith ◽  
M. Maher Hulou ◽  
Sandra C. Yan ◽  
David J. Cote ◽  
Brian V. Nahed ◽  
...  

OBJECT Recent studies have examined the impact of perceived medicolegal risk and compared how this perception impacts defensive practices within the US. To date, there have been no published data on the practice of defensive medicine among neurosurgeons in Canada. METHODS An online survey containing 44 questions was sent to 170 Canadian neurosurgeons and used to measure Canadian neurosurgeons’ perception of liability risk and their practice of defensive medicine. The survey included questions on the following domains: surgeon demographics, patient characteristics, type of physician practice, surgeon liability profile, policy coverage, defensive behaviors, and perception of the liability environment. Survey responses were analyzed and summarized using counts and percentages. RESULTS A total of 75 neurosurgeons completed the survey, achieving an overall response rate of 44.1%. Over one-third (36.5%) of Canadian neurosurgeons paid less than $5000 for insurance annually. The majority (87%) of Canadian neurosurgeons felt confident with their insurance coverage, and 60% reported that they rarely felt the need to practice defensive medicine. The majority of the respondents reported that the perceived medicolegal risk environment has no bearing on their preferred practice location. Only 1 in 5 respondent Canadian neurosurgeons (21.8%) reported viewing patients as a potential lawsuit. Only 4.9% of respondents would have selected a different career based on current medicolegal risk factors, and only 4.1% view the cost of annual malpractice insurance as a major burden. CONCLUSIONS Canadian neurosurgeons perceive their medicolegal risk environment as more favorable and their patients as less likely to sue than their counterparts in the US do. Overall, Canadian neurosurgeons engage in fewer defensive medical behaviors than previously reported in the US.


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