Energy Dispersive X-Ray Analysis of Ocean Ferromanganese Crusts Using Conventional ZAF Corrections

Ocean ferromanganese crusts are composed of interlayered phases of manganese oxide, iron oxide and oxyhydroxide, calcium carbonate/phosphate, silica, and alumino-silicates. These interlayers are so thin and fine-grained that each phase could not be isolated under the beam of a scanning electron microscope for quantitative x-ray microanalysis. A test was conducted to determine if the grain size of the phases was small enough to allow conventional ZAF techniques to be used without serious errors in the results. A synthetic ferromanganese crust was prepared by pelletization of a 1:1 mix of two fine-grained (\u3c5 \u3emicrometer) components. The mean of the energy dispersive analyses of the mix, using an area-scan method (25 x 30 μm square), shows good agreement (generally within 5 to 10 percent, relative) to the arithmetic combination of the x-ray analyses of each component. Analyses performed by x-ray fluorescence, inductively-coupled argon plasma spectroscopy, flame atomic absorption spectrometry, ion chromatography, spectrophotometry and sulfur analyzer are provided for the purposes of comparison. The results of the energy dispersive analyses were normalized using ignition-loss values and a calculation of fluorine from the P2O5 content to reflect the presence of light elements (Z\u3c11). The results were reasonably consistent with other methods of bulk analyses, demonstrating that this method can be used where other instrumentation is not available or where sample size is too small for other methods

Ferromanganese micronodules from the surficial sediments of Georges Bank

Ferromanganese micronodules have been found on Georges Bank, off the U.S. northeast coast, distributed throughout the surficial sediments within an area about 125 km long and at least 12 km wide. These coarse, sand-sized concretions have precipitated from metal-rich interstitial waters and contain many of the textural and structural features common to other neritic nodules. Most of the nodules have accreted around detrital grains, and X-ray powder diffraction analyses indicate the presence of geothite and vernadite (δ-MnO2) in the ferromanganese layers. Chemical analyses of the micronodules, when compared with similar data on deep-sea manganese nodules, reveal lower Mn/Fe ratios, significantly higher concentrations of V and As, comparable values of Mo, and an order of magnitude less of Co, Ni, Ce and most other metals

Aortic valvuloplasty of calcific aortic stenosis with monofoil and trefoil balloon catheters: practical considerations

In order to evaluate the relation between balloon design (monofoil, trefoil) and valvular configuration, experimental aortic valvuloplasty was performed in four post-mortem hearts with calcific aortic sten

Association of the PHACTR1/EDN1 genetic locus with spontaneous coronary artery dissection

Background: Spontaneous coronary artery dissection (SCAD) is an increasingly recognized cause of acute coronary syndromes (ACS) afflicting predominantly younger to middle-aged women. Observational studies have reported a high prevalence of extracoronary vascular anomalies, especially fibromuscular dysplasia (FMD) and a low prevalence of coincidental cases of atherosclerosis. PHACTR1/EDN1 is a genetic risk locus for several vascular diseases, including FMD and coronary artery disease, with the putative causal noncoding variant at the rs9349379 locus acting as a potential enhancer for the endothelin-1 (EDN1) gene. Objectives: This study sought to test the association between the rs9349379 genotype and SCAD. Methods: Results from case control studies from France, United Kingdom, United States, and Australia were analyzed to test the association with SCAD risk, including age at first event, pregnancy-associated SCAD (P-SCAD), and recurrent SCAD. Results: The previously reported risk allele for FMD (rs9349379-A) was associated with a higher risk of SCAD in all studies. In a meta-analysis of 1,055 SCAD patients and 7,190 controls, the odds ratio (OR) was 1.67 (95% confidence interval [CI]: 1.50 to 1.86) per copy of rs9349379-A. In a subset of 491 SCAD patients, the OR estimate was found to be higher for the association with SCAD in patients without FMD (OR: 1.89; 95% CI: 1.53 to 2.33) than in SCAD cases with FMD (OR: 1.60; 95% CI: 1.28 to 1.99). There was no effect of genotype on age at first event, P-SCAD, or recurrence. Conclusions: The first genetic risk factor for SCAD was identified in the largest study conducted to date for this condition. This genetic link may contribute to the clinical overlap between SCAD and FMD

Annotated record of the detailed examination of Mn micronodules from stations over George Bank, Atlantic Ocean

Ferromanganese micronodules have been found on Georges Bank, off the U.S. northeast coast, distributed throughout the surficial sediments within an area about 125 km long and at least 12 km wide. These coarse, sand-sized concretions have precipitated from metal-rich interstitial waters and contain many of the textural and structural features common to other neritic nodules. Most of the nodules have accreted around detrital grains, and X-ray powder diffraction analyses indicate the presence of geothite and vernadite ( delta -MnO sub(2)) in the ferromanganese layers. Chemical analyses of the micronodules, when compared with similar data on deep-sea manganese nodules, reveal lower Mn/Fe ratios, significantly higher concentrations of V and As, comparable values of Mo, and an order of magnitude less of Co, Ni, Ce and most other, metals

Ferromanganese nodules and crusts chemical analysis of samples from cruise L583HW (R/V S.P. Lee) using X-ray

The cooperative cruise of the R/V S.P. Lee in 1983 provided an excellent opportunity for a wide-range interlaboratory study on samples of crusts ground and sieved aboard the vessel. Analytical data on splits of approximately 56 samples were performed by the U.S. Geological Survey laboratories in Reston Virginia and Woods Hole Massachusetts, (see Chapter V), the Bureau of Mines laboratory in Avondale, Maryland, and the laboratory of the German Geological Survey in Hannover, Federal Republic of Germany. At USGS Woods-Hole, 2.0 cm thick mini-slabs from ferromanganese crust or nodule outer surface were separated into horizons and layers. They were ground and sieved through a 105 micron nylon mesh. Remaining ferromanganese material was removed by washing with 10 percent hydroxylamine hydrochloride (NH2OH.HCL) and 1 percent oxalic acid. Samples were first dried at 110°C overnight for the determination of hydroscopic water (H2O-). Major and minor element concentrations were determined by X-ray fluorescence spectrometry

PORTASPEC shipboard determined chemical composition of ferromanganese crusts for L9-84-CP expedition (R/V S.P. Lee)

Mobile laboratories are important to the exploration geochemist because they offer rapid chemical analyses of geologic materials in the field. This permits modification of the sampling plan in response to significant findings, rather than following a planned sampling scheme and leaving any follow-up to a later time. The portable PORTASPEC X-ray spectrograph (Pitchford Scientific instruments Division of Hankison Corporation) Model 2501 was used on ferromanganese crusts during the L9-84-CP (R/V S.P. Lee) expedition by the United States Geological Survey. The composition in major elements was averaged over a collection of samples for each station

Chemical composition of oxide-phosphorite pavement from the Blake Plateau under various preparation treatment

Sample preparation technique is critical for valid chemical analyses. A main source of error comes from the fact that the great specific surface area of crusts or nodules enhances their tendency to retain or attract hygroscopic moisture. Variable treatment of this moisture can in extreme cases lead to analytical value differences as great as 40-50 %. In order to quantify these influences, samples of ferromanganese oxide-phosphorite pavement from the Blake Plateau have been subjected to various drying techniques before analysis using X-ray fluorescence

Ferromanganese crusts and nodules chemical analyses from the USGS Woods Hole analytical laboratories

Beginning in 1983 the USGS searched major oceanographic institution dredge archives for samples and data relevant to the USGS Woods-Hole Ferromanganese Crust Data Base. With the cooperation of the institutions more than 600 samples were collected from twelve institutions and brought to the U.S. Geological Survey Branch of Atlantic Marine Geology in Woods Hole, Mass, for geochemical analysis. At USGS Woods-Hole, 2.0 cm thick mini-slabs from ferromanganese crust or nodule outer surface were separated into horizons and layers. They were ground and sieved through a 105 micron nylon mesh. Remaining ferromanganese material was removed by washing with 10 percent hydroxylamine hydrochloride (NH2OH.HCL) and 1 percent oxalic acid. Samples were first dried at 110°C overnight for the determination of hydroscopic water (H2O-). For some samples, the structural water content was determined by the loss (Loss at Ignition (LOI)) from heating at 500°C for one hour followed by a heating at 1000°C for one more hour. Major and minor element concentrations were determined by X-ray fluorescence spectrometry