Chemical and isotopic compositions of hydrothermal manifestations and minerals from the Broken Spur hydrothermal field

A representative collection of hydrothermal manifestations was sampled practically from all hydrothermal mounds of the Broken Spur hydrothermal vent field with use of the Mir manned submersibles during three cruises of R/V Akademik Mstislav Keldysh. Mineral associations characteristic for different morphological types of sulfide ores from hydrothermal pipes, plates, and diffusers are assessed. Particular attention is paid to distribution of minor elements and their distribution patterns determined by mineralogical zonation. Measured isotopic composition of sulfur in sulfide minerals varies from 0.4 to 5.2 per mil that indicates their similarity with ores from the Snake Pit vent field and is related to dilution of hot ore-bearing solutions by seawater and reduction of water sulfate ions to H2S with heavy isotopic composition.

Mössbauer study at DSDP Hole 95-612

57Fe Mössbauer spectra of 15 oceanic sediment samples collected from Site 612 (Deep Sea Drilling Project Leg 95) were recorded. These spectra showed that most of the iron in the sediments was present as high-spin, paramagnetic Fe2+ and Fe3+. The ferrous iron was mainly distributed in terrigenous clays and biogenic carbonates. The variation of the Mössbauer parameters for Fe2+ with sub-bottom depth suggests that the main Fe2+-bearing component changed with geologic time. The amount of iron in each iron-bearing phase as estimated from the corresponding peak areas in the spectra also changed with depth. These variations in the Mössbauer parameters and peak areas are correlated with lithologic changes in the sediment column.

Long Term Outcomes Following Catheter Ablation of Ventricular Tachycardia in Patients with and without Structural Heart Disease.

BACKGROUND Long-term outcomes following ventricular tachycardia (VT) ablation are sparsely described. OBJECTIVES To describe long term prognosis following VT ablation in patients with no structural heart disease (no SHD), ischemic (ICM) and non-ischemic cardiomyopathy (NICM). METHODS Consecutive patients (n=695; no SHD 98, ICM 358, NICM 239 patients) ablated for sustained VT were followed for a median of 6 years. Acute procedural parameters (complete success [non-inducibility of any VT]) and outcomes after multiple procedures were reported. RESULTS Compared with patients with no SHD or NICM, ICM patients were the oldest, had more males, lowest left ventricular ejection fraction (LVEF), highest drug failures, VT storms and number of inducible VTs. Complete procedure success was highest in no SHD, compared ICM and NICM patients (79%, 56%, 60% respectively, P<0.001). At 6 years, ventricular arrhythmia (VA)-free survival was highest in no SHD (77%) than ICM (54%) and NICM (38%, P<0.001) and overall survival was lowest in ICM (48%), followed by NICM (74%) and no SHD patients (100%, P<0.001). Age, LVEF, presence of SHD, acute procedural success (non-inducibility of any VT), major complications, need for non-radiofrequency ablation modalities, and VA recurrence were independently associated with all cause mortality. CONCLUSIONS Long term follow up following VT ablation shows excellent prognosis in the absence of SHD, highest VA recurrence and transplantation in NICM and highest mortality in patients with ICM. The extremely low mortality for those without SHD suggests that VT in this population is very rarely an initial presentation of a myopathic process.

On increasing the effective aperture of antennas by data processing /

Includes bibliographical references (p. 58-59)

Application of density functional theory to equilibrium adsorption of argon and nitrogen on amorphous silica surface

We present a new version of non-local density functional theory (NL-DFT) adapted to description of vapor adsorption isotherms on amorphous materials like non-porous silica. The novel feature of this approach is that it accounts for the roughness of adsorbent surface. The solid–fluid interaction is described in the same framework as in the case of fluid–fluid interactions, using the Weeks–Chandler–Andersen (WCA) scheme and the Carnahan–Starling (CS) equation for attractive and repulsive parts of the Helmholtz free energy, respectively. Application to nitrogen and argon adsorption isotherms on non-porous silica LiChrospher Si-1000 at their boiling points, recently published by Jaroniec and co-workers, has shown an excellent correlative ability of our approach over the complete range of pressures, which suggests that the surface roughness is mostly the reason for the observed behavior of adsorption isotherms. From the analysis of these data, we found that in the case of nitrogen adsorption short-range interactions between oxygen atoms on the silica surface and quadrupole of nitrogen molecules play an important role. The approach presented in this paper may be further used in quantitative analysis of adsorption and desorption isotherms in cylindrical pores such as MCM-41 and carbon nanotubes.

Predictors of responsiveness to physiotherapy management of cervicogenic headache

A recent randomized controlled trial tested the effectiveness of therapeutic exercise and manipulative therapy on 200 subjects with cervicogenic headache. Although treatments were efficacious, 25% of patients did not achieve a clinically acceptable outcome - 50% reduction in headache frequency This study aimed to identify predictors from variables in subjects' demographics and headache history which might identify those who did or did not achieve a 50-79% or 80-100% reduction in headache immediately after the active treatments and 12 months postintervention. The results revealed no consistent pattern of predictors, although the absence of light-headedness indicated higher odds of achieving either a 50-79% [odds ratio (OR) = 5.45) or 80-100% (OR = 5.7) reduction in headache frequency in the long term. Headaches of at least moderate intensity, the patient's age and chronicity of headache did not mitigate against a successful outcome from physiotherapy intervention.

Focused, eight-element transceive phased array coil for parallel magnetic resonance imaging of the chest-theoretical considerations

A new transceive system for chest imaging for MRI applications is presented. A focused, eight-element transceive torso phased array coil is designed to investigate transmitting a focused radiofrequency field deep within the torso and to enhance signal homogeneity in the heart region. The system is used in conjunction with the SENSE reconstruction technique to enable focused parallel imaging. A hybrid finite-difference-time-domain/method-of-moments method is used to accurately predict the radiofrequency behavior inside the human torso. The simulation results reported herein demonstrate the feasibility of the design concept, which shows that radiofrequency field focusing with SENSE reconstruction is theoretically achievable. (c) 2005 Wiley-Liss, Inc.

Kinetics of reduction of FeO from slag by graphite and coal chars

The rates of reduction of FeO from iron-saturated FeO-CaO-Al2O3-SiO2 slags by graphite, coke, bituminous coal and anthracitic coal chars at temperatures in the range 1 673-1873 K have been measured using a sessile drop technique. The extents of reaction were determined using EPMA analysis of quenched samples, and on line gas analysis using a quadrupole mass spectrometer. The reaction rates have been shown to be dependent critically on carbon type. For the reaction geometry used in this investigation the reduction rates of graphite and coke are observed to be faster than with coal chars. This unexpected finding is shown to be associated with differences in the dominant chemical and mass transfer mechanisms occurring at the reaction interface. High reaction rates are observed to occur with the formation of liquid Fe-C alloy product and the associated gasification of carbon from the alloy. The rates of reduction by coal chars are determined principally by the chemical reaction at the carbon/gas interface and slag phase mass transfer.

Multiple-acquisition parallel imaging combined with a transceive array for the amelioration of high-field RF distortion: a modeling study

A new method for ameliorating high-field image distortion caused by radio frequency/tissue interaction is presented and modeled, The proposed method uses, but is not restricted to, a shielded four-element transceive phased array coil and involves performing two separate scans of the same slice with each scan using different excitations during transmission. By optimizing the amplitudes and phases for each scan, antipodal signal profiles can be obtained, and by combining both images together, the image distortion can be reduced several-fold. A hybrid finite-difference time-domain/method-of-moments method is used to theoretically demonstrate the method and also to predict the radio frequency behavior inside the human head. in addition, the proposed method is used in conjunction with the GRAPPA reconstruction technique to enable rapid imaging. Simulation results reported herein for IIT (470 MHz) brain imaging applications demonstrate the feasibility of the concept where multiple acquisitions using parallel imaging elements with GRAPPA reconstruction results in improved image quality. (c) 2006 Wiley Periodicals, Inc.

Direct quantification of rare earth element concentrations in natural waters by ICP-MS

A direct quadrupole ICP-MS technique has been developed for the analysis of the rare earth elements and yttrium in natural waters. The method has been validated by comparison of the results obtained for the river water reference material SLRS-4 with literature values. The detection limit of the technique was investigated by analysis of serial dilutions of SLRS-4 and revealed that single elements can be quantified at single-digit fg/g concentrations. A coherent normalised rare earth pattern was retained at concentrations two orders of magnitude below natural concentrations for SLRS-4, demonstrating the excellent inter-element accuracy and precision of the method. The technique was applied to the analysis of a diluted mid-salinity estuarine sample, which also displayed a coherent normalised rare earth element pattern, yielding the expected distinctive marine characteristics. (c) 2006 Published by Elsevier Ltd.

The behaviour of the rare earth elements during estuarine mixing-revisited

Complete rare earth element (except Eu) and Y concentrations from the estuarine mixing zone (salinity =0.2 to 33) of Elimbah Creek, Queensland, Australia, were measured by quadrupole ICP-MS without preconcentration. High sampling density in the low salinity regime along with high quality data allow accurate tracing of the development of the typical marine rare earth element anomalies as well as Y/Ho fractionation. Over the entire estuary, the rare earth elements are strongly removed relative to a freshwater endmember (60-80% removal). This large overall removal occurs despite a strong remineralisation peak (190% for La, 130% for Y relative to the freshwater endmember) in the mid-salinity zone. Removal and remineralisation are accompanied by fractionation of the original (freshwater) rare earth element pattern, resulting in light rare earth element depletion. Estuarine fractionation generates a large positive La anomaly and a superchondritic Y/Ho ratio. Conversely, we observe no evidence to support the generation of the negative Ce anomaly in the estuary. With the exception of Ce, the typical marine rare earth element features can thus be attributed to estuarine mixing processes. The persistence of these features in hydrogenous sediments for at least 3.71 Ga highlights the importance of estuarine processes for marine chemistry on geological timescales. (c) 2005 Elsevier B.V. All rights reserved.

Surface studies in ultra high vacuum

An ultra high vacuum system capable of attaining pressures of 10-12 mm Hg was used for thermal desorption experiments. The metal chosen for these experiments was tantalum because of its suitability for thermal desorption experiments and because relatively little work has been done using this metal. The gases investigated were carbon monoxide, hydrogen and ethylene. The kinetic and thermodynamic parameters relating to the desorption reaction were calculated and the values obtained related to the reaction on the surface. The thermal desorption reaction was not capable of supplying all the information necessary to form a complete picture of the desorption reaction. Further information was obtained by using a quadrupole mass spectrometer to analyse the desorbed species. The identification of the desorbed species combined with the value of the desorption parameters meant that possible adatom structures could be postulated. A combination of these two techniques proved to be a very powerful tool when investigating gas-metal surface reactions and gave realistic values for the measured parameters such as the surface coverage, order of reaction, the activation energy and pre-exponential function for desorption. Electron microscopy and X-ray diffraction were also used to investigate the effect of the gases on the metal surface.

Development of novel mass spectrometric methods for identifying HOCl-induced modifications to proteins

Protein oxidation is thought to contribute to a number of inflammatory diseases, hence the development of sensitive and specific analytical techniques to detect oxidative PTMs (oxPTMs) in biological samples is highly desirable. Precursor ion scanning for fragment ions of oxidized amino acid residues was investigated as a label-free MS approach to mapping specific oxPTMs in a complex mixture of proteins. Using HOCl-oxidized lysozyme as a model system, it was found that the immonium ions of oxidized tyrosine and tryptophan formed in MS(2) analysis could not be used as diagnostic ions, owing to the occurrence of isobaric fragment ions from unmodified peptides. Using a double quadrupole linear ion trap mass spectrometer, precursor ion scanning was combined with detection of MS(3) fragment ions from the immonium ions and collisionally-activated decomposition peptide sequencing to achieve selectivity for the oxPTMs. For chlorotyrosine, the immonium ion at 170.1 m/z fragmented to yield diagnostic ions at 153.1, 134.1, and 125.1 m/z, and the hydroxytyrosine immonium ion at 152.1 m/z gave diagnostic ions at 135.1 and 107.1 m/z. Selective MS(3) fragment ions were also identified for 2-hydroxytryptophan and 5-hydroxytryptophan. The method was used successfully to map these oxPTMs in a mixture of nine proteins that had been treated with HOCl, thereby demonstrating its potential for application to complex biological samples.

Use of narrow mass-window, high-resolution extracted product ion chromatograms for the sensitive and selective identification of protein modifications

Protein modifications, including oxidative modifications, glycosylations, and oxidized lipid-protein adducts, are becoming increasingly important as biomarkers and in understanding disease etiology. There has been a great deal of interest in mapping these on Apo B100 from low density lipoprotein (LDL). We have used extracted ion chromatograms of product ions generated using a very narrow mass window from high-resolution tandem mass spectrometric data collected on a rapid scanning quadrupole time-of-flight (QTOF) instrument, to selectively and sensitively detect modified peptides and identify the site and nature of a number of protein modifications in parallel. We have demonstrated the utility of this method by characterizing for the first time oxidized phospholipid adducts to LDL and human serum albumin and for the detection of glycosylation and kynurenin formation from the oxidation of tryptophan residues in LDL. © 2013 American Chemical Society.