Atmospheric pressure ionization for gas chromatography-high resolution mass spectrometry determination of polychlorinated naphthalenes in marine sediments.

In this work, the performance of the atmospheric pressure chemical ionization (APCI) and photoionization (APPI) was assessed to develop a new selective and sensitive gas chromatography-high resolution mass spectrometry (GC-HRMS) method for the determination of polychlorinated naphthalenes (PCNs) in sediment samples. The capability of both APCI and APPI sources for the ionization of PCNs was investigated, showing the formation of the molecular ion and the [M‒Cl+O]‒ ion in positive and negative ion modes, respectively. Positive ion APCI provided high responses using high corona ion current, while the use of high vapour pressure dopant-solvents, such as toluene in positive mode and diethyl ether in the negative mode, was required to achieve high ionization efficiencies in APPI. The performance of the two API sources in the PCN determination by GC-HRMS were compared and the best results were achieved using the GC-APPI(+)-HRMS (Orbitrap) system. The GC-APPI(+)-HRMS (Orbitrap) method was applied to the characterization of Halowax mixtures and the analysis of marine sediments collected near to the coastal area of Barcelona (NE, Spain), demonstrating a great detection capability with low method limits of detection (0.2-1.6 pg g-1 dry weight), good precision (RSD <15%) and trueness (relative error <13%). Total PCN concentrations ranged from 0.35 to 5.0 ng g-1 dry weight and the presence of related compounds, such as polychlorinated biphenyls (PCBs), was also detected by combining positive and negative ion modes, providing complementary information to better monitor of all PCN congener groups. The results presented here show the feasibility of the GC-APPI-HRMS method for the suitable determination of PCNs.

Ionic Liquid Stationary Phase for Improving Comprehensive Two-dimensional Gas Chromatographic Separation of Polychlorinated Naphthalenes.

The performance of comprehensive two-dimensional gas chromatography coupled to mass spectrometry (GC×GC-MS) using a column combination of a non-polar stationary phase (DB-5MS) and an ionic liquid stationary phase (SLB-IL60) in the first- and the second dimension has been evaluated for the suitable separation of polychlorinated naphthalenes (PCNs). The optimization of the GC×GC-MS method was carried out using different oven temperature programs and modulation conditions, achieving the best results using a ramp temperature rate of 0.75 °C min-1 and a modulation time of 12 s. Under these conditions, efficient separation of all PCN congeners present in Halowax formulations was achieved in 140 min, resolving some critical closed eluting isomers, such as CN-33/34/37, highly toxic CN-66/67 or CN-71/72 pairs, among others. These findings represent a significant improvement in the congener-specific separation of PCNs over the 1D-GC and GC×GC methodologies already published and the DB-5MS × SLB-IL60 column combination offered the orthogonality required for the congener-specific determination with a high peak capacity. The GC×GC-MS method was applied to the characterisation of Halowax formulations, obtaining similar compositional profiles than those previously reported.

Detachment in Fusion Plasmas with Symmetry Breaking Magnetic Perturbation Fields.

Power exhaust from the bulk plasma is significantly altered by symmetry breaking magnetic perturbation fields, because these create direct connections (perturbed field lines) from the confined high temperature plasma to solid surfaces. The same amount of power is distributed among those new exhaust channels as for a symmetric magnetic configuration, which reduces the local upstream heat flux flowing down the perturbed field lines, thereby making access to detachment easier (i.e., at lower upstream density) for the divertor plasma near the location corresponding to the symmetric magnetic separatrix. However, the divertor plasma regions with connection to the bulk plasma are extended nonaxisymmetrically further outside, where significant heat loads occur, unlike in the symmetric configuration. The temperature remains high at those locations, which reduces the divertor plasma dissipation capacity, making the mitigation of heat loads more difficult to achieve.

Preparation, analysis, and application of coated glass targets for the Wendelstein 7-X laser blow-off system.

Coated glass targets are a key component of the Wendelstein 7-X laser blow-off system that is used for impurity transport studies. The preparation and analysis of these glass targets as well as their performance is examined in this paper. The glass targets have a high laser damage threshold and are coated via physical vapor deposition with µm thick films. In addition, nm-thin layers of Ti are used as an interface layer for improved ablation efficiency and reduced coating stress. Hence, the metallic or ceramic coating has a lateral homogeneity within 2% and contaminants less than 5%, being optimal for laser ablation processing. With this method, a short (few ms) and well defined pulse of impurities with about 1017 particles can be injected close to the last closed flux surface of Wendelstein 7-X. In particular, a significant amount of atoms with a velocity of about 1 km/s enters the plasma within 1 ms. The atoms are followed by a negligible concentration of slower clusters and macro-particles. This qualifies the use of the targets and applied laser settings for impurity transport studies with the laser blow-off system in Wendelstein 7-X.

Wisconsin In Situ Penning (WISP) gauge: A versatile neutral pressure gauge to measure partial pressures in strong magnetic fields.

A new type of in-vessel Penning gauge, the Wisconsin In Situ Penning (WISP) gauge, has been developed and successfully operated in the Wendelstein 7-X (W7-X) island divertor baffle and vacuum vessel. The capacity of the quantitative measurements of the neutral reservoir for light impurities, in particular, helium, is important for tokamaks as well as stellarator divertors in order to avoid fuel dilution and radiative energy loss. Penning gauges assisted by spectroscopy are a powerful tool to obtain the total neutral pressure as well as fractional neutral pressures of specific impurities. The WISP gauge is a miniaturized Penning gauge arrangement, which exploits the ambient magnetic field of magnetic confinement fusion experiments to establish the Penning discharge. Then, in situ spectroscopy is conducted to separate the fractional neutral pressures of hydrogen, helium, and possibly also other impurities. The WISP probe head was qualified using the magnetic field of the Magnetized Dusty Plasma Experiment at Auburn University between 0.25 T and 3.5 T [E. Thomas et al., J. Plasma Phys. 81, 345810206 (2015)]. The in-depth quantitative evaluation for hydrogen and helium will be shown as well as an exploration of nitrogen, argon, and neon. A power law scaling between current I and pressure p, I = f(Gas,V) · pn(Gas, B), was shown. The factor f is gas and anode potential dependent, while n is gas and magnetic field strength dependent. Pressure measurements from 0.1 mbar and down to 1 × 10-5 mbar were achieved, demonstrating a reliable operating range for relevant pressure levels in the divertor and main vessel regions in current and future fusion devices, with a time resolution of up to 1 kHz. The lowest achievable pressure measurement increases with an increase in B and can be shifted with the anode potential V. At W7-X, the WISP probe head was mounted on an immersion tube setup that passes through the cryostat and places the probe head close to the plasma. Two probe heads were positioned in different divertor pump gaps, top and bottom, and one close to the plasma on the midplane in one module. The gauges were in situ calibrated together with the ASDEX pressure gauges [G. Haas and H.-S. Bosch, Vacuum 51, 39 (1998)]. Data were taken during the entire operation phase 1.2b, and measurements were coherent with other neutral gas pressure gauges. For the spectroscopic partial pressure measurements, channels of a spectroscopic detection system based on photo-multipliers, a so-called filterscope [R. J. Colchin et al., Rev. Sci. Instrum. 74, 2068 (2003)], provided by the Oak Ridge National Lab were used.

Helium line ratio spectroscopy for high spatiotemporal resolution plasma edge profile measurements at ASDEX Upgrade (invited).

The thermal helium beam edge diagnostic has recently been upgraded at the ASDEX Upgrade (AUG) tokamak experiment. Line ratio spectroscopy on neutral helium is a valuable tool for simultaneous determination of the electron temperature and density of plasmas. The diagnostic now offers a temporal resolution of 900 kHz with a spatial resolution of up to 3 mm at 32 lines of sight (LOS) simultaneously. The LOS covers a radial region of 8.5 cm, starting at the limiter radius and reaching into the confined region beyond the separatrix. Two components are of particular importance for the aforementioned hardware improvements. The first is the optical head, which collects the light from the experiment. Equipped with an innovative clamping system for optical fiber ends, an arbitrary distribution pattern of LOS can be achieved to gain radial and poloidal profiles. The second major development is a new polychromator system that measures the intensity of the 587 nm, 667 nm, 706 nm, and 728 nm helium lines simultaneously for 32 channels with filter-photomultiplier tube arrays. Thus, the thermal helium beam diagnostic supplements the AUG edge diagnostics, offering fast and spatially highly resolved electron temperature and density profile measurements that cover the plasma edge and scrape-off layer region. Plasma fluctuations, edge localized modes, filaments, and other turbulent structures are resolved, allowing analysis of their frequency and localization or their propagation velocity.

Fast piezoelectric valve offering controlled gas injection in magnetically confined fusion plasmas for diagnostic and fuelling purposes.

In magnetically confined fusion plasmas controlled gas injection is crucial for plasma fuelling as well as for various diagnostic applications such as active spectroscopy. We present a new, versatile system for the injection of collimated thermal gas beams into a vacuum chamber. This system consists of a gas pressure chamber, sealed by a custom made piezo valve towards a small capillary for gas injection. The setup can directly be placed inside of the vacuum chamber of fusion devices as it is small and immune against high magnetic fields. This enables gas injection close to the plasma periphery with high duty cycles and fast switch on/off times ≲ 0.5 ms. In this work, we present the design details of this new injection system and a systematic characterization of the beam properties as well as the gas flowrates which can be accomplished. The thin and relatively short capillary yields a small divergence of the injected beam with a half opening angle of 20°. The gas box is designed for pre-fill pressures of 10 mbar up to 100 bars and makes a flowrate accessible from 1018 part/s up to 1023 part/s. It hence is a versatile system for both diagnostic as well as fuelling applications. The implementation of this system in ASDEX Upgrade will be described and its application for line ratio spectroscopy on helium will be demonstrated on a selected example.

Synthetic plasma edge diagnostics for EMC3-EIRENE, highlighted for Wendelstein 7-X.

Interpretation of spectroscopic measurements in the edge region of high-temperature plasmas can be a challenge since line of sight integration effects make direct interpretation in terms of quantitative, local emission strengths often impossible. The EMC3-EIRENE code-a 3D fluid edge plasma and kinetic neutral gas transport code-is a suitable tool for full 3D reconstruction of such signals. A versatile synthetic diagnostic module has been developed recently which allows the realistic 3D setup of various plasma edge diagnostics to be captured. We highlight these capabilities with two examples for Wendelstein 7-X (W7-X): a visible camera for the analysis of recycling, and a coherent-imaging system for velocity measurements.

Feasibility of line-ratio spectroscopy on helium and neon as edge diagnostic tool for Wendelstein 7-X.

A beam emission spectroscopy system on thermal helium (He) and neon (Ne) has been set up at Wendelstein 7-X to measure edge electron temperature and density profiles utilizing the line-ratio technique or its extension by the analysis of absolutely calibrated line emissions. The setup for a first systematic test of these techniques of quantitative atomic spectroscopy in the limiter startup phase (OP1.1) is reported together with first measured profiles. This setup and the first results are an important test for developing the technique for the upcoming high density, low temperature island divertor regime.

Time-dependent analysis of visible helium line-ratios for electron temperature and density diagnostic using synthetic simulations on NSTX-U.

Helium line-ratios for electron temperature (Te) and density (ne) plasma diagnostic in the Scrape-Off-Layer (SOL) and edge regions of tokamaks are widely used. Due to their intensities and proximity of wavelengths, the singlet, 667.8 and 728.1 nm, and triplet, 706.5 nm, visible lines have been typically preferred. Time-dependency of the triplet line (706.5 nm) has been previously analyzed in detail by including transient effects on line-ratios during gas-puff diagnostic applications. In this work, several line-ratio combinations within each of the two spin systems are analyzed with the purpose of eliminating transient effects to extend the application of this powerful diagnostic to high temporal resolution characterization of plasmas. The analysis is done using synthetic emission modeling and diagnostic for low electron density NSTX SOL plasma conditions by several visible lines. Quasi-static equilibrium and time-dependent models are employed to evaluate transient effects of the atomic population levels that may affect the derived electron temperatures and densities as the helium gas-puff penetrates the plasma. The analysis of a wider range of spectral lines will help to extend this powerful diagnostic to experiments where the wavelength range of the measured spectra may be constrained either by limitations of the spectrometer or by other conflicting lines from different ions.

Spectroscopic imaging of limiter heat and particle fluxes and the resulting impurity sources during Wendelstein 7-X startup plasmas.

A combined IR and visible camera system [G. A. Wurden et al., "A high resolution IR/visible imaging system for the W7-X limiter," Rev. Sci. Instrum. (these proceedings)] and a filterscope system [R. J. Colchin et al., Rev. Sci. Instrum. 74, 2068 (2003)] were implemented together to obtain spectroscopic data of limiter and first wall recycling and impurity sources during Wendelstein 7-X startup plasmas. Both systems together provided excellent temporal and spatial spectroscopic resolution of limiter 3. Narrowband interference filters in front of the camera yielded C-III and Hα photon flux, and the filterscope system provided Hα, Hß, He-I, He-II, C-II, and visible bremsstrahlung data. The filterscopes made additional measurements of several points on the W7-X vacuum vessel to yield wall recycling fluxes. The resulting photon flux from both the visible camera and filterscopes can then be compared to an EMC3-EIRENE synthetic diagnostic [H. Frerichs et al., "Synthetic plasma edge diagnostics for EMC3-EIRENE, highlighted for Wendelstein 7-X," Rev. Sci. Instrum. (these proceedings)] to infer both a limiter particle flux and wall particle flux, both of which will ultimately be used to infer the complete particle balance and particle confinement time τP.

Development of miniaturized, spectroscopically assisted Penning gauges for fractional helium and hydrogen neutral pressure measurements.

Direct measurements of the helium (He) fractional neutral pressure in the neutral gas around fusion devices is challenging because of the small mass difference between the abundant D2 molecules and the He ash which will be produced by deuterium-tritium fusion. To study He exhaust, an in situ Penning gauge system is being developed at UW-Madison that is optimized for good pressure and high spectroscopic sensitivity. Three different anode geometries have been studied regarding their vacuum electrostatic fields, light output, and ion current. The light output of the two new anode configurations are at least one order of magnitude above the currently available designs, hence improving the spectroscopic sensitivity at similar total neutral pressure resolution.

Status of the diagnostics development for the first operation phase of the stellarator Wendelstein 7-X.

An overview of the diagnostics which are essential for the first operational phase of Wendelstein 7-X and the set of diagnostics expected to be ready for operation at this time are presented. The ongoing investigations of how to cope with high levels of stray Electron Cyclotron Resonance Heating (ECRH) radiation in the ultraviolet (UV)/visible/infrared (IR) optical diagnostics are described.

Predation drives stable coexistence ratios between red and green pea aphid morphs.

We conducted field surveys and experiments to evaluate the hypothesis that predation is an important driving factor determining the degree of coexistence between red and green morphs of the pea aphid Acyrthosiphon pisum. Theory suggests that the different colour morphs are differentially susceptible to natural enemies and selection by predation which in turn leads to variable relative abundances of red and green morphs among host plants across landscapes. Our field surveys on pea and alfalfa revealed, however, that the colour morphs tended to coexist closely in a ratio of one red to three green aphids across fields with different host plant monocultures. Experimentation involving manipulation of the relative abundances of the two colour morphs on host plants pea and alfalfa with and without predator presence revealed that red morphs had higher or same fitness (per capita reproduction) than green morphs on both pea and alfalfa only when in the proportion of one red/three green proportion. Moreover, experimentation evaluating predator efficiency revealed that red morphs are safest from predation when in a 1 : 3 ratio with green morphs. These results suggest that in addition to predation selection effects, red morphs may behaviourally choose to associate with green morphs in a narrow 1 : 3 ratio to maximize their fitness. This evidence, along with existing published data on red and green morph anti-predator behaviour indicates that a 1 : 3 red and green morph coexistence ratio is driven by a balance between predation pressure and behavioural assorting by red morphs across landscapes. In this way predators may have ecological-evolutionary consequences for traits that affect the colour morphs' proportion and tolerances to selective pressure.

HELIOS: a helium line-ratio spectral-monitoring diagnostic used to generate high resolution profiles near the ion cyclotron resonant heating antenna on TEXTOR.

Radial profiles of electron temperature and density are measured at high spatial (∼1 mm) and temporal (≥10 µs) resolution using a thermal supersonic helium jet. A highly accurate detection system is applied to well-developed collisional-radiative model codes to produce the profiles. Agreement between this measurement and an edge Thomson scattering measurement is found to be within the error bars (≲20%). The diagnostic is being used to give profiles near the ion cyclotron resonant heating antenna on TEXTOR to better understand RF coupling to the core.

Metabolic effects of short-term GLP-1 treatment in insulin resistant heart failure patients.

We studied the metabolic effects of 48-h GLP-1 treatment in insulin resistant heart failure patients.In a randomized placebo-controlled double-blinded cross-over study, 11 non-diabetic HF patients with IHD received 48-h GLP-1 and placebo-infusion. We applied OGTT, hyperinsulinemic clamp, indirect calorimetry, forearm, and tracer methods.7 insulin resistant HF (EF 28%±2) patients completed the protocol. GLP-1 decreased plasma glucose levels (p=0.048) and improved glucose tolerance. 4 patients had hypoglycemic events during GLP-1 vs. none during placebo. GLP-1 treatment tended to increase whole body protein turnover (p=0.08) but did not cause muscle wasting. No significant changes in circulating levels of insulin, glucagon, free fatty acids or insulin sensitivity were detected.GLP-1 treatment decreased glucose levels and increased glucose tolerance in insulin resistant HF patients with IHD. Hypoglycemia was common and may limit the use of GLP-1 in these patients. Insulin sensitivity, lipid-, and protein metabolism remained unchanged.Data were collected at the examinational laboratories of Department of Endocrinology and Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark.

Effects of adrenaline on lactate, glucose, lipid and protein metabolism in the placebo controlled bilaterally perfused human leg.

AIM: Adrenaline has widespread metabolic actions, including stimulation of lipolysis and induction of insulin resistance and hyperlactatemia. Systemic adrenaline administration, however, generates a very complex hormonal and metabolic scenario. No studies employing regional, placebo controlled and adrenaline infusion exist. Our study was designed to test the hypothesis that local placebo controlled leg perfusion with adrenaline directly increases local lactate release, stimulates lipolysis, induces insulin resistance and leaves protein metabolism unaffected. METHODS: We studied seven healthy volunteers with bilateral femoral vein and artery catheters during 3-h basal and 3-h hyperinsulinemic (0.6 mU kg(-1) min(-1) ) euglycemic clamp conditions. One femoral artery was perfused with saline and the other with adrenaline (0.4 µg min m(-2) ). Lipid metabolism was quantified with [9,10-(3) H] palmitate and amino acid metabolism with (15) N-phenylalanine and lactate and glucose by raw arterio-venous differences. RESULTS: Femoral vein plasma adrenaline increased ≈eightfold in the perfused leg with unaltered blood flows. Adrenaline perfusion significantly increased local leg lactate release from 0.01 to 0.25 mmol min(-1) per leg, palmitate release in the basal state 11.5-16.9 µmol min(-1) per leg and during the clamp 2.62-8.44 µmol min(-1) per leg. Glucose uptake decreased during the clamp from ≈180 to 30 µmol min(-1) per leg. Phenylalanine kinetics was not affected by adrenaline. CONCLUSION: Adrenaline directly increases lactate release and lipolysis and inhibits insulin-stimulated glucose uptake in the perfused human leg. Adrenaline has no direct effects on peripheral amino acid metabolism. Adrenaline-induced lactate release from striated muscle may be an important mechanism underlying hyperlactatemia in the critically ill.

Insulin dose-response studies in severely insulin-resistant type 2 diabetes--evidence for effectiveness of very high insulin doses.

AIM: To combat diabetic complications strict glycaemic control is desirable in type 2 diabetes, but some patients are severely insulin resistant and it is not known whether high doses of insulin are effective. This study was designed to determine the acute dose-response effects of insulin in patients with type 2 diabetes and severe insulin resistance. METHODS: We included eight insulin-resistant (mean insulin dose: 186 IU/day; body mass index: 35) subjects with type 2 diabetes in a single-blinded, randomized crossover study. Each subject was studied on two occasions. On each occasion, subjects underwent two 3-h hyperinsulinaemic euglycaemic clamps. The subjects were randomized to two low-dose insulin infusions (0.5 and 1.5 mU/kg/min in random order) on one occasion and to two high-dose insulin infusions (3.0 and 5.0 mU/kg/min in random order) on another occasion. RESULTS: On all occasions, steady-state glucose infusion rates (SSGIRs) were accomplished and we observed a clear dose-response relationship with GIR values of 0.4 ± 0.2 (s.e.), 2.6 ± 0.6, 3.7 ± 0.8 and 4.9 ± 0.9 mg/kg/min during the 0.5, 1.5, 3.0 and 5.0 mU/kg/min insulin infusions, respectively (p < 0.001). Likewise, there was a dose-dependent suppression of endogenous glucose production (EGP) (p < 0.009), plasma free fatty acids (FFAs) (p < 0.001) and plasma glucagon (p = 0.001). CONCLUSIONS: Our results show that the insulin dose response in terms of GIR and EGP is preserved for insulin doses corresponding to >800 IU/day, suggesting effectiveness of very high insulin doses in severely insulin-resistant subjects.

Keystone predation and plant species coexistence: the role of carnivore hunting mode.

Plant communities are shaped by bottom-up processes such as competition for nutrients and top-down processes such as herbivory. Although much theoretical work has studied how herbivores can mediate plant species coexistence, indirect effects caused by the carnivores that consume herbivores have been largely ignored. These carnivores can have significant indirect effects on plants by altering herbivore density (density-mediated effects) and behavior (trait-mediated effects). Carnivores that differ in traits, particularly in their hunting mode, cause different indirect effects on plants and, ultimately, different plant community compositions. We analyze a food-web model to determine how plant coexistence is affected by herbivore-consuming carnivores, contrasting those causing only density-mediated effects with those causing trait-mediated effects as well. In the latter case, herbivores can adjust their consumption of a refuge plant species. We derive a general graphical model to study the interplay of density- and trait-mediated effects. We show that carnivores eliciting both effects can sustain plant species coexistence, given intermediate intensities of behavioral adjustments. Coexistence is more likely, and more stable, if the refuge plant is competitively dominant. These results extend our understanding of carnivore indirect effects in food webs and show that behavioral effects can have major consequences on plant community structure, stressing the need for theoretical approaches that incorporate dynamical traits.