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Hyperpolarized (HP) xenon-129 (129Xe), when dissolved in blood, has two NMR resonances: one in red blood cells (RBC) and one in plasma. The impact of numerous blood components on these resonances, however, has not yet been investigated. This study evaluates the effects of elevated glucose levels on the chemical shift (CS) andT2*relaxation times of HP 129Xe dissolved in sterile citrated sheep blood for the first time. HP 129Xe was mixed with sheep blood samples premixed with a stock glucose solution using a liquid–gas exchange module. Magnetic resonance spectroscopy was performed on a 3T clinical MRI scanner using a custom-built quadrature dual-tuned 129Xe/1H coil. We observed an additional resonance for the RBCs (129Xe-RBC1) for the increased glucose levels. The CS of 129Xe-RBC1 and 129Xe-plasma peaks did not change with glucose levels, while the CS of 129Xe-RBC2 (original RBC resonance) increased linearly at a rate of 0.015 ± 0.002 ppm/mM with glucose level. 129Xe-RBC1T2*values increased nonlinearly from 1.58 ± 0.24 ms to 2.67 ± 0.40 ms. As a result of the increased glucose levels in blood samples, the novel additional HP 129Xe dissolved phase resonance was observed in blood and attributed to the 129Xe bound to glycated hemoglobin (HbA1c).

PURPOSE In this study, we compared hyperpolarized 3He and 129Xe images from patients with cystic fibrosis using two commonly applied magnetic resonance sequences, standard gradient echo (GRE) and balanced steady-state free precession (TrueFISP) to quantify regional similarities and differences in signal distribution and defect analysis. MATERIALS AND METHODS Ten patients (7M/3F) with cystic fibrosis underwent hyperpolarized gas MR imaging with both 3He and 129Xe. Six had MRI with both GRE, and TrueFISP sequences and four patients had only GRE sequence but not TrueFISP. Ventilation defect percentages (VDPs) were calculated as lung voxels with

Purpose: The existing tools to quantify lung function in interstitial lung diseases have significant limitations. Lung MRI imaging using inhaled hyperpolarized xenon-129 gas (129Xe) as a contrast agent is a new technology for measuring regional lung physiology. We sought to assess the utility of the 129Xe MRI in detecting impaired lung physiology in usual interstitial pneumonia (UIP). Materials and methods: After institutional review board approval and informed consent and in compliance with HIPAA regulations, we performed chest CT, pulmonary function tests (PFTs), and 129Xe MRI in 10 UIP subjects and 10 healthy controls. Results: The 129Xe MRI detected highly heterogeneous abnormalities within individual UIP subjects as compared to controls. Subjects with UIP had markedly impaired ventilation (ventilation defect fraction: UIP: 30 ± 9%; healthy: 21 ± 9%; p = 0.026), a greater amount of 129Xe dissolved in the lung interstitium (tissue-to-gas ratio: UIP: 1.45 ± 0.35%; healthy: 1.10 ± 0.17%; p = 0.014), and impaired 129Xe diffusion into the blood (RBC-to-tissue ratio: UIP: 0.20 ± 0.06; healthy: 0.28 ± 0.05; p = 0.004). Most MRI variables had no correlation with the CT and PFT measurements. The elevated level of 129Xe dissolved in the lung interstitium, in particular, was detectable even in subjects with normal or mildly impaired PFTs, suggesting that this measurement may represent a new method for detecting early fibrosis. Conclusion: The hyperpolarized 129Xe MRI was highly sensitive to regional functional changes in subjects with UIP and may represent a new tool for understanding the pathophysiology, monitoring the progression, and assessing the effectiveness of treatment in UIP.

Carbon net erosion and deposition at the test divertor unit (TDU) of Wendelstein 7-X (W7-X) were measured for the discharge period OP 1.2b in the year 2018 using 18 specially prepared target elements in all 10 TDUs. These had lengths between 30 and 60 cm and were coated with marker layers for erosion/deposition investigations of 5–10 μm carbon on top of about 300 nm molybdenum. The marker layer thicknesses were measured by elastic backscattering spectrometry (EBS) before and after plasma exposure using 2.5 MeV protons; the surface morphology was investigated using scanning electron microscopy (SEM) and focused ion beam cross-sectioning (FIB), the surface roughness was determined using a two-dimensional optical profiler. Plasma-exposed surfaces were considerably smoother than unexposed surfaces with decreased mean roughness and a shift of the inclination angle distribution towards lower values. The erosion on the 10 TDUs was unequal within a factor of about two. During the discharge period in total 20.4 ± 5.7 g carbon was eroded from the 10 TDUs. Adjacent to the strike line some deposition of carbon was observed. Compared to the discharge period OP 1.2a in the year 2017, the net carbon erosion rate dropped by a factor of 5–6 due to regular boronizations, which reduced the oxygen (and subsequently also the carbon) content in the plasma by 1–2 orders of magnitude. The significance of erosion/deposition processes for long-pulse discharges is discussed.

In this study, we compared hyperpolarizedTen patients (7M/3F) with cystic fibrosis underwent hyperpolarized gas MR imaging with bothA significant correlation was demonstrated betweenIn patients with cystic fibrosis, the selection of hyperpolarized

Rationale: Adverse events have limited the use of bronchial thermoplasty (BT) in severe asthma. Objectives: We sought to evaluate the effectiveness and safety of using (129)Xe magnetic resonance imaging ((129)Xe MRI) to prioritize the most involved airways for guided BT. Methods: Thirty subjects with severe asthma were imaged with volumetric computed tomography and (129)Xe MRI to quantitate segmental ventilation defects. Subjects were randomized to treatment of the six most involved airways in the first session (guided group) or a standard three-session BT (unguided). The primary outcome was the change in Asthma Quality of Life Questionnaire score from baseline to 12 weeks after the first BT for the guided group compared with after three treatments for the unguided group. Measurements and Main Results: There was no significant difference in quality of life after one guided compared with three unguided BTs (change in Asthma Quality of Life Questionnaire guided = 0.91 [95% confidence interval, 0.28–1.53]; unguided = 1.49 [95% confidence interval, 0.84–2.14]; P = 0.201). After one BT, the guided group had a greater reduction in the percentage of poorly and nonventilated lung from baseline when compared with unguided (−17.2%; P = 0.009). Thirty-three percent experienced asthma exacerbations after one guided BT compared with 73% after three unguided BTs (P = 0.028). Conclusions: Results of this pilot study suggest that similar short-term improvements can be achieved with one BT treatment guided by (129)Xe MRI when compared with standard three-treatment-session BT with fewer periprocedure adverse events.

The assessment of early pulmonary disease and its severity can be difficult in young children, as procedures such as spirometry cannot be performed on them. Computed tomography provides detailed structural images of the pulmonary parenchyma, but its major drawback is that the patient is exposed to ionizing radiation. In this context, magnetic resonance imaging (MRI) is a promising technique for the evaluation of pediatric lung disease, especially when serial imaging is needed. Traditionally, MRI played a small role in evaluating the pulmonary parenchyma. Because of its low proton density, the lungs display low signal intensity on conventional proton-based MRI. Hyperpolarized (HP) gases are inhaled contrast agents with an excellent safety profile and provide high signal within the lung, allowing for high temporal and spatial resolution imaging of the lung airspaces. Besides morphologic information, HP MR images also offer valuable information about pulmonary physiology. HP gas MRI has already made new contributions to the understanding of pediatric lung diseases and may become a clinically useful tool. In this article, we discuss the HP gas MRI technique, special considerations that need to be made when imaging children, and the role of MRI in 2 of the most common chronic pediatric lung diseases, asthma and cystic fibrosis. We also will discuss how HP gas MRI may be used to evaluate normal lung growth and development and the alterations occurring in chronic lung disease of prematurity and in patients with a congenital diaphragmatic hernia.

Polarized 3 He has contributed to breakthroughs in particle physics, neutron scattering, and lung imaging, mostly by optical pumping of liter quantities in valved cells or in sealed cells pumped in situ. Only metastability exchange optical pumping currently meets the demand for delivering large quantities of highly polarized 3 He to external volumes. Our development program is under way to achieve medium to large-scale spin-exchange optical pumping of 3 He. Thin-walled aluminosilicate cells placed in contact with thermal reservoirs inside a pressure vessel were optically pumped with kilowatt-scale lasers spectrally narrowed to match pressure-broadened absorption linewidths. We report here the key elements of this program and significant milestones: multi-liter volume valved cells that provide long longitudinal lifetimes that reached polarization as high as 85% inside a thermally stable and pressurized environment.

Hyperpolarized (HP) gases are a new class of contrast agents that permit to obtain high temporal and spatial resolution magnetic resonance images (MRI) of the lung airspaces. HP gas MRI has become important research tool not only for morphological and functional evaluation of normal pulmonary physiology but also for regional quantification of pathologic changes occurring in several lung diseases. The purpose of this work is to provide an introduction to MRI using HP noble gases, describing both the basic principles of the technique and the new information about lung disease provided by clinical studies with this method. The applications of the technique in normal subjects, smoking related lung disease, asthma, and cystic fibrosis are reviewed.

Hyperpolarized (HP) gases are a new class of contrast agents that permit to obtain high temporal and spatial resolution magnetic resonance images (MRI) of the lung airspaces. HP gas MRI has become important research tool not only for morphological and functional evaluation of normal pulmonary physiology but also for regional quantification of pathologic changes occurring in several lung diseases. The purpose of this work is to provide an introduction to MRI using HP noble gases, describing both the basic principles of the technique and the new information about lung disease provided by clinical studies with this method. The applications of the technique in normal subjects, smoking related lung disease, asthma, and cystic fibrosis are reviewed.

Purpose To investigate whether chemical shift saturation recovery (CSSR) MR spectroscopy with hyperpolarized xenon-129 is sensitive to the pulsatile nature of pulmonary blood flow during the cardiac cycle. Methods A CSSR pulse sequence typically uses radiofrequency (RF) pulses to saturate the magnetization of xenon-129 dissolved in lung tissue followed, after a variable delay time, by an RF excitation and subsequent acquisition of a free-induction decay. Thereby it is possible to monitor the uptake of xenon-129 by lung tissue and extract physiological parameters of pulmonary gas exchange. In the current studies, the delay time was instead held at a constant value, which permitted observation of xenon-129 gas uptake as a function of breath-hold time. CSSR studies were performed in 13 subjects (10 healthy, 2 chronic obstructive pulmonary disease [COPD], 1 second-hand smoke exposure), holding their breath at total lung capacity. Results The areas of the tissue/plasma and the red-blood-cell peaks in healthy subjects varied by an average of and , respectively, during the cardiac cycle. In 2 subjects with COPD these peak pulsations were not detectable during at least part of the measurement period. Conclusion: CSSR spectroscopy is sufficiently sensitive to detect oscillations in the xenon-129 gas-uptake rate associated with the cardiac cycle. Magn Reson Med, 2015. © 2015 Wiley Periodicals, Inc.

Magnetic-resonance spectroscopy and imaging using hyperpolarized xenon-129 show great potential for evaluation of the most important function of the human lung -- gas exchange. In particular, chemical shift saturation recovery (CSSR) xenon-129 spectroscopy provides important physiological information for the lung as a whole by characterizing the dynamic process of gas exchange, while dissolved-phase (DP) xenon-129 imaging captures the time-averaged regional distribution of gas uptake by lung tissue and blood. Herein, we present recent advances in assessing lung function using CSSR spectroscopy and DP imaging in a total of 45 subjects (23 healthy, 13 chronic obstructive pulmonary disease (COPD) and 9 asthma). From CSSR acquisitions, the COPD subjects showed red blood cell to tissue-plasma (RBC-to-TP) ratios below the average for the healthy subjects (p < 0.001), but significantly higher septal wall thicknesses as compared with the healthy subjects (p < 0.005); the RBC-to-TP ratios for the asthmatic subjects fell outside two standard deviations (either higher or lower) from the mean of the healthy subjects, although there was no statistically significant difference for the average ratio of the study group as a whole. Similarly, from the 3D DP imaging acquisitions, we found that all the ratios (TP to gas phase (GP), RBC to GP, RBC to TP) measured in the COPD subjects were lower than those from the healthy subjects (p < 0.05 for all ratios), while these ratios in the asthmatic subjects differed considerably between subjects. Despite having been performed at different lung inflation levels, the RBC-to-TP ratios measured by CSSR and 3D DP imaging were fairly consistent with each other, with a mean difference of 0.037 (ratios from 3D DP imaging larger). In ten subjects the RBC-to-GP ratios obtained from the 3D DP imaging acquisitions were also highly correlated with their diffusing capacity of the lung for carbon monoxide per unit alveolar volume ratios measured by pulmonary function testing (R = 0.91).

Purpose To present in vivo, human validation of a previously proposed method to measure key pulmonary parameters related to lung microstructure and physiology. Some parameters, such as blood–air barrier thickness, cannot be measured readily by any other noninvasive modality. Methods Healthy volunteers (n = 12) were studied in 1.5T and 3T whole body human scanners using hyperpolarized xenon. Xenon uptake by lung parenchyma and blood was measured using a chemical shift saturation recovery sequence. Both dissolved-xenon peaks at 197 ppm and 217–218 ppm were fitted against a model of xenon exchange (MOXE) as functions of exchange time. Parameters related to lung function and structure can be obtained by fitting to this model. Results The following results were obtained from xenon uptake (averaged over all healthy volunteers): surface-area-to-volume ratio = 210 ± 50 cm−1; total septal wall thickness = 9.2 ± 6.5 μm; blood-air barrier thickness = 1.0 ± 0.3 μm; hematocrit = 27 ± 4%; pulmonary capillary blood transit time = 1.3 ± 0.3 s, in good agreement with literature values from invasive experiments. More detailed fitting results are listed in the text. Conclusion The initial in vivo human results demonstrate that our proposed methods can be used to noninvasively determine lung physiology by simultaneous quantification of a few important pulmonary parameters. This method is highly promising to become a versatile screening method for lung diseases. Magn Reson Med 71:339–344, 2014. © 2013 Wiley Periodicals, Inc.

Since August 2011 JET operates with the ITER-like wall comprising bulk Be tiles, bulk W tiles and W coated CFC tiles with a thickness of 10–15 μm and 20–25 μm. In order to evaluate behavior of the W coatings to a cyclic thermal loading relevant to JET operation, high heat flux (HHF) tests have been carried out up to 5100 pulses with an electron beam facility at peak temperatures of 1000 °C, 1250 °C and 1450 °C. The pulse duration was 24 s. Optical inspections of the W layer performed periodically by interrupting the test revealed small delaminations with the size of 50–500 μm. The dependence of the delamination percentage on the number of pulses can be seen as a degradation curve for each particular W coating. In this way the thermo-mechanical properties of the W coatings can be characterized quantitatively. Thermal fatigue and carbidization of the tungsten due to the diffusion of the carbon from the substrate have been recognized as mechanisms for degradation of the coatings. Tungsten carbides have been identified by using TEM (transmission electron microscopy) diffraction analysis on FIB (focused ion beam) prepared cross-section samples subjected to HHF tests. Nano-pores developed at the CFC–Mo and Mo–W interfaces during the tests might be also responsible for the degradation of the coating.

The primary function of the lung is exchange of respiratory gases. Impaired gas exchange in pulmonary disease can cause symptomatic shortness of breath, and in severe disease can progress to respiratory failure and death. Although our knowledge of gas-exchange status in individual patients is derived primarily from whole-lung measurements, gas exchange can vary substantially within the lung, especially for heterogeneous conditions like chronic obstructive pulmonary disease (COPD). Thus, regional assessment of ventilation and gas uptake would permit investigation of the fundamental process of gas exchange and improve our understanding of how heterogeneous diseases such as COPD affect gas exchange. In addition, the ability to easily and non-invasively quantify regional gas uptake may prove invaluable for evaluating new therapeutics for lung diseases. Nonetheless, despite many recent advances in medical imaging technology, there is no clinical imaging method that permits quantitative regional assessment of both gas delivery to the alveolar airspaces and gas uptake into the lung parenchyma and blood. Numerous unique approaches for evaluating the structure and function of the lung have been developed by using the hyperpolarized noble gases helium-3 (He3) and xenon-129 (Xe129) as inhaled, gaseous contrast agents for MRI (1–5). In particular, the relatively high solubility of xenon in biological tissues (6), combined with an enormous range of chemical shifts upon solution which result from the extraordinary sensitivity of xenon to its environment (7), permit gas exchange and uptake to be explored using hyperpolarized Xe129 (8–14). Following inhalation, multiple MRI spectral peaks from Xe129, each associated with a physically different compartment, can be detected in the lung (8,15–17). Although most of the Xe129 remains in the lung airspaces (“gas-phase” xenon) and corresponds to a single large spectral peak, about 1–2% of Xe129 dissolves in the lung parenchyma and blood (“dissolved-phase” xenon) and gives rise to smaller peaks with chemical shifts of approximately 200 ppm from the gas peak (8,15–17). Driven by diffusion, dissolved-phase xenon is in dynamic equilibrium with xenon in the airspaces. The associated continual exchange of xenon atoms between the gas and dissolved compartments, which have distinctly different resonance frequencies, is key for permitting gas uptake and exchange to be assessed using hyperpolarized Xe129 MRI. The quantitative characteristics of the exchange and uptake processes are determined by physiologically relevant parameters, such as the thickness of the blood-gas barrier (12), the ratio of functional tissue volume to alveolar volume (18), and the surface-to-volume ratio (10). Even though the fraction of xenon dissolved in the lung parenchyma and blood is quite small, early studies of the human lung demonstrated that it was possible to detect these compartments of dissolved-phase Xe129 in whole-lung spectra (16). Images of dissolved-phase Xe129 were subsequently acquired in small animals by using multiple inhalations of hyperpolarized gas (12,19,20), although with current technology such a multiple-inhalation protocol is not feasible in humans. Muradian et al (21) also demonstrated the possibility of obtaining gas-phase and dissolved-phase images in humans at low field strength (0.2T) by decomposing the total xenon signal using the 3-point Dixon method. With recent improvements in gas-polarization systems (22), however, liter quantities of hyperpolarized Xe129 can be obtained with sufficiently high polarization to permit direct imaging of the dissolved phase in humans during a single breath-hold period. In 2010, two research groups demonstrated 3D imaging of dissolved-phase Xe129 in the human lung (23,24). While these two studies represent an important step toward realizing the potential wealth of information offered by dissolved-phase imaging on the functional status of the lung, they demonstrated only the ability to assess the total dissolved-phase signal, and not its individual components including Xe129 dissolved in lung parenchyma/plasma as well as Xe129 dissolved in red blood cells (RBCs). The recent study in animals by Driehuys et al (12) has already demonstrated the substantial potential value of discriminating the individual contributions from parenchyma/plasma and RBCs for understanding the physiological consequences of pulmonary disease. The overall goal of this study was to advance the capability of dissolved-phase hyperpolarized Xe129 imaging in humans by developing a robust approach for regional assessment of the individual signal contributions from Xe129 dissolved in the lung parenchyma/plasma and RBCs. Specifically, we aimed to: (1) develop a pulse sequence that permits regional mapping of both ventilation (Xe129 in the alveolar airspaces) and the fractions of Xe129 dissolved in the parenchyma/plasma and RBCs from multi-echo 3D data acquired in a single breath hold with a duration tolerable for subjects with lung disease; and (2) perform an exploratory study to characterize the signal fractions obtained from parenchyma/plasma and RBCs in healthy subjects compared to those from subjects with pulmonary disease, including COPD and asthma. Acquisition of ventilation and gas-uptake images with matched spatial resolution during the same breath hold provides the necessary basis for normalizing the dissolved-phase signals (24), thus permitting quantitative comparison of the parenchyma/plasma and RBC fractions among subjects. For simplicity, the parenchyma/plasma component will be referred to using the single term “tissue” for the remainder of the paper.

We describe a novel apparatus for large-scale production of polarized 3He using Spin-Exchange Optical Pumping (SEOP). The large optical pumping cell is enclosed inside a pressure containment vessel to equalize the differential pressure across the glass cell walls. Numerical simulations of laser absorption and spin-transfer guided our choice of pressure, temperature, and laser power. Computational fluid dynamics simulations of the two-zone thermal bath environment revealed buoyancy-induced flow which favored operation inclined at an angle. We prepared and tested three separate 8.5 liter cells at internal pressures up to six amagat (50 bar-liters) with hybrid alkali ratios of K:Rb of 10:1 by mass (4.4:1 by number ratio) and at temperatures up to 250°C. An early prototype used a 1.4 kW broadband laser, while our most recent prototype incorporated a new 2.2kW spectrally narrowed external cavity laser. Using small surface coil NMR to measure polarization, we obtained spin-up rates greater than 20% per hour consistent with our numerical simulations. Unfortunately, each cell installation to date has been compromised, limiting T1 relaxation times to 12 hours and asymptotic polarizations to values below 50%. If a cell could be installed with 50 hour lifetime and X-factor of 0.2, this polarizer will deliver 50 liters of over 70% polarized 3He twice each day.

Hyperpolarized xenon-129 has the potential to become a noninvasive contrast agent for lung MRI. In addition to its utility for imaging of ventilated airspaces, the property of xenon to dissolve in lung tissue and blood upon inhalation provides the opportunity to study gas exchange. Implementations of imaging protocols for obtaining regional parameters that exploit the dissolved phase are limited by the available signal-to-noise ratio, excitation homogeneity, and length of acquisition times. To address these challenges, a 32-channel receive-array coil complemented by an asymmetric birdcage transmit coil tuned to the hyperpolarized xenon-129 resonance at 3 T was developed. First results of spin-density imaging in healthy subjects and subjects with obstructive lung disease demonstrated the improvements in image quality by high-resolution ventilation images with high signal-to-noise ratio. Parallel imaging performance of the phased-array coil was demonstrated by acceleration factors up to three in 2D acquisitions and up to six in 3D acquisitions. Transmit-field maps showed a regional variation of only 8% across the whole lung. The newly developed phased-array receive coil with the birdcage transmit coil will lead to an improvement in existing imaging protocols, but moreover enable the development of new, functional lung imaging protocols based on the improvements in excitation homogeneity, signal-to-noise ratio, and acquisition speed.

Hyperpolarized xenon-129 is a noninvasive contrast agent for lung MRI, which upon inhalation dissolves in parenchymal structures, thus mirroring the gas-exchange process for oxygen in the lung. Multiple-exchange-time xenon polarization transfer contrast (MXTC) MRI is an implementation of the XTC MRI technique in four dimensions (three spatial dimensions plus exchange time). The aim of this study was to evaluate the sensitivity of MXTC MRI for the detection of microstructural deformations of the healthy lung in response to gravity-induced tissue compression and the degree of lung inflation. MXTC MRI was performed in four rabbits and in three healthy human volunteers. Two lung function parameters, one related to tissue- to alveolar-volume ratio and the other to average septal-wall thickness, were determined regionally. A significant gradient in MXTC MRI parameters, consistent with gravity-induced lung tissue deformation in the supine imaging position, was found at low lung volumes. At high lung volumes, parameters were generally lower and the gradient in parameter values was less pronounced. Results show that MXTC MRI permits the quantification of subtle changes in healthy lung microstructure. Further, only structures participating in gas exchange are represented in MXTC MRI data, which potentially makes the technique especially sensitive to pathological changes in lung microstructure affecting gas exchange. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.

The paper gives a short overview on tungsten (W) coatings deposited by various methods on carbon materials (carbon fibre composite – CFC and fine grain graphite – FGG). Vacuum Plasma Spray (VPS), Chemical Vapor Deposition (CVD) and Physical Vapor Deposition (PVD) techniques are analyzed in respect with the characteristics and performances of the W coatings. A particular attention is paid to the Combined Magnetron Sputtering and Ion Implantation (CMSII) technique, which was developed during the last 4 years from laboratory to industrial scale and it is successfully applied for W coating (10–15 μm and 20–25 μm) of more than 2500 tiles for the ITER-like Wall project at JET and ASDEX Upgrade. This technique involves simultaneously magnetron sputtering and high energy (tens of keV) ion implantation. Due to the ion bombardment a stress relief occurs within the coating enabling its growth without delamination to a relatively large thickness. In addition, in order to adjust the thermal expansion mismatch between CFC and W, a Mo interlayer of 2–3 μm is currently used. Experimentally, W/Mo coatings with a thickness up to 50 μm were produced and successfully tested in the GLADIS ion beam facility up to 23 MW/m2.

Purpose: To develop and test a method to noninvasively assess the functional lung microstructure. Materials and Methods: The Multiple exchange time Xenon polarization Transfer Contrast technique (MXTC) encodes xenon gas-exchange contrast at multiple delay times permitting two lung-function parameters to be derived: (i) MXTC-F, the long exchange-time depolarization value, which is proportional to the tissue to alveolar-volume ratio and (ii) MXTC-S, the square root of the xenon exchange-time constant, which characterizes thickness and composition of alveolar septa. Three healthy volunteers, one asthmatic, and two chronic obstructive pulmonary disease (COPD) (GOLD stage I and II) subjects were imaged with MXTC MRI. In a subset of subjects, hyperpolarized xenon-129 ADC MRI and CT imaging were also performed. Results: The MXTC-S parameter was found to be elevated in subjects with lung disease (P-value = 0.018). In the MXTC-F parameter map it was feasible to identify regional loss of functional tissue in a COPD patient. MXTC-F maps showed excellent regional correlation with CT and ADC (P ≥ 0.90) in one COPD subject. Conclusion: The functional tissue-density parameter MXTC-F showed regional agreement with other imaging techniques. The newly developed parameter MXTC-S, which characterizes the functional thickness of alveolar septa, has potential as a novel biomarker for regional parenchymal inflammation or thickening. J. Magn. Reson. Imaging 2011;33:1052–1062. © 2011 Wiley-Liss, Inc.

In this paper the processes occurring at the plasma–cathode interface (carbon absorption and sputtering) which are responsible for the structure of the compound layer (CL) are discussed in conjunction with the ternary Fe–N–C phase diagram. The influence of the gas composition, including oxygen, on the development of the CL is also investigated. Based on the mechanisms of plasma nitrocarburising described in this paper a technique to produce CLs with a structure close to epsilon monophase was developed and applied to plain carbon steels.

This paper reports the main results of the RFX-mod fusion science activity since the last 2014 IAEA Fusion Energy Conference. The RFX-mod device is characterized by a unique flexibility in terms of accessible magnetic configurations. Axisymmetric and helically shaped Reversed-field pinch equilibria have been studied, along with tokamak plasmas in a wide range of q(a) regimes (spanning from 4 down to 1.2 values). The full range of magnetic configurations in between the two, the so-called ultra low-q ones, has been explored, with the aim of studying specific physical issues common to all equilibria, such as, for example, the density limit phenomenon. The powerful RFX-mod feedback control system has been exploited for MHD control, which allowed to extend the range of experimental parameters, as well as to induce specific magnetic perturbations for the study of 3D effects. In particular, transport, edge and isotope effect in 3D equilibria have been investigated, along with runaway mitigations through induced magnetic perturbations. The first transitions to H-mode in circular and D-shaped tokamak plasmas have been obtained thanks to an active modification of the edge electric field through a polarized electrode. The experiments are supported by intense modelling with 3D MHD, gyrokinetic, guiding center and transport codes. Proposed modifications to the RFX-mod device, which will enable further contributions to the solution of key issues in the roadmap to ITER and DEMO, are also briefly presented.

The majority of researchers investigating hyperpolarized gas MRI as a candidate functional lung imaging modality have used (3)He as their imaging agent of choice rather than (129)Xe. This preference has been predominantly due to, (3)He providing stronger signals due to higher levels of polarization and higher gyromagnetic ratio, as well as its being easily available to more researchers due to availability of polarizers (USA) or ease of gas transport (Europe). Most researchers agree, however, that hyperpolarized (129)Xe will ultimately emerge as the imaging agent of choice due to its unlimited supply in nature and its falling cost. Our recent polarizer technology delivers vast improvements in hyperpolarized (129)Xe output. Using this polarizer, we have demonstrated the unique property of xenon to measure alveolar surface area noninvasively. In this article, we describe our human protocols and their safety, and our results for the measurement of the partial pressure of pulmonary oxygen (pO(2)) by observation of (129)Xe signal decay. We note that the measurement of pO(2) by observation of (129)Xe signal decay is more complex than that for (3)He because of an additional signal loss mechanism due to interphase diffusion of (129)Xe from alveolar gas spaces to septal tissue. This results in measurements of an equivalent pO(2) that accounts for both traditional T(1) decay from pO(2) and that from interphase diffusion. We also provide an update on new technological advancements that form the foundation for an improved compact design polarizer as well as improvements that provide another order-of-magnitude scale-up in xenon polarizer output.

We describe a prototype system built to allow open-access very-low-field MRI of human lungs using laser-polarized (3)He gas. The system employs an open four-coil electromagnet with an operational B(0) field of 4 mT, and planar gradient coils that generate gradient fields up to 0.18 G/cm in the x and y direction and 0.41 G/cm in the z direction. This system was used to obtain (1)H and (3)He phantom images and supine and upright (3)He images of human lungs. We include discussion on challenges unique to imaging at 50 -200 kHz, including noise filtering and compensation for narrow-bandwidth coils.

The structure, thickness and adhesion to the substrate of the hard coatings used for protection against wear and corrosion are very important characteristics and they are strongly dependent on the internal stress induced into the coating during its growth. Development of a new class of coatings with a hardness of 2500–4500 HV0.1 and a thickness of 10–50 μm might increase significantly the application area of PVD coating in hydraulics, automotive, forming and even cutting tools. An ion assisted deposition method that combines magnetron sputtering and ion implantation (CMSII) as simultaneous processes has been used to produce nc-Ti 2 N/nc-TiN nanocomposite layers with such properties. In this paper, the cantilever method was used for in situ monitoring of the internal stress during the coating deposition. Generally, the internal stress produced by CMSII method is about half of that produced by magnetron sputtering without ion implantation. The structure of these coatings were analyzed by means of TEM. The adhesion and fracture properties of the coatings were analyzed by a mini version of a tensile test.

Using a relative simple experimental method, the sputtering rate has been measured under specific plasma nitriding conditions. The influence of gas composition and total pressure on the sputtering rate has been investigated. Depending on these factors, the sputtering rate varies in the range of 0.02–0.12 μm/h. The sputtered material has been analyzed as well. The results indicated that the phase constitution of this material is similar to that of the compound layer.

To investigate whether chemical shift saturation recovery (CSSR) MR spectroscopy with hyperpolarized xenon-129 is sensitive to the pulsatile nature of pulmonary blood flow during the cardiac cycle.A CSSR pulse sequence typically uses radiofrequency (RF) pulses to saturate the magnetization of xenon-129 dissolved in lung tissue followed, after a variable delay time, by an RF excitation and subsequent acquisition of a free-induction decay. Thereby it is possible to monitor the uptake of xenon-129 by lung tissue and extract physiological parameters of pulmonary gas exchange. In the current studies, the delay time was instead held at a constant value, which permitted observation of xenon-129 gas uptake as a function of breath-hold time. CSSR studies were performed in 13 subjects (10 healthy, 2 chronic obstructive pulmonary disease [COPD], 1 second-hand smoke exposure), holding their breath at total lung capacity.The areas of the tissue/plasma and the red-blood-cell peaks in healthy subjects varied by an average of 1.7±0.7% and 15.1±3.8%, respectively, during the cardiac cycle. In 2 subjects with COPD these peak pulsations were not detectable during at least part of the measurement period.CSSR spectroscopy is sufficiently sensitive to detect oscillations in the xenon-129 gas-uptake rate associated with the cardiac cycle.

We describe the principle of operation, design implementation, and initial performance of a high production xenon-129 polarizing system. The polarizer is built on the concept of counterflow-polarizing using a high-power spectrally-narrowed laser, a multi-channel copper column, and a dynamic cryo-accumulation system. We present a general description of the implemented system with focus on the key components. Polarization values of up to 60% in the delivery dose Tedlar bags were observed at a clinical site where human lung imaging studies are performed. More than 700 litres of xenon were polarized for human lung imaging experiments at a single imaging site over a two year period.

We performed investigations to determine the lifetime of tungsten coatings on carbon under high heat flux with respect to tungsten carbide formation. Tungsten coatings with a molybdenum interlayer were deposited by combined magnetron sputtering and ion implantation. These coatings were heat treated in a vacuum furnace. Subsequently the fraction of the coating thickness which had converted into carbide, was determined by focussed ion beam preparation and electron microscopy. This thickness was found to extend from 10 μm to 18 μm for heat treatments between 2 and 20 h at 1350 °C. Such coatings were then exposed to high heat flux pulses of 16.5 MW/m 2 with pulse durations of 1.5 s. A clear threshold behaviour was found: While after 2 h of heat treatment no coating failure was found, the delaminated surface fraction was up to 5% after treatment for 5 h and up to 25% after treatment for 20 h at 1350 °C.

Hyperpolarized (HP) gases are a new class of contrast agents that permit to obtain high temporal and spatial resolution magnetic resonance images (MRI) of the lung airspaces. HP gas MRI has become important research tool not only for morphological and functional evaluation of normal pulmonary physiology but also for regional quantification of pathologic changes occurring in several lung diseases. The purpose of this work is to provide an introduction to MRI using HP noble gases, describing both the basic principles of the technique and the new information about lung disease provided by clinical studies with this method. The applications of the technique in normal subjects, smoking related lung disease, asthma, and cystic fibrosis are reviewed.

During the C28-C30 campaigns the ITER-like Wall (ILW) was periodically inspected by IVIS (InVessel Inspection System) without breaking the vacuum. After these campaigns the JET chamber was opened and the wall was inspected with a high resolution camera. The marker tiles were removed from the chamber and they have been inspected in the beryllium handling facility. The overall picture of the ILW after more than 3000 pulses looks good. However there are a few modifications such as deposition of Be on some W coated tiles, local destruction of the W coating by runway electrons in an emergency shutdown, arcing on particular W coated tiles, small delaminations on G6 and G8 divertor tiles. These aspects together with the results of high heat flux tests carried out with W coated CFC samples in Magnum-PSI are discussed in the paper.

The ITER-like wall (ILW) at JET is a unique opportunity to study the combination of material (beryllium and tungsten) that will be used for the plasma facing components (PFC) in ITER. Both the limiters (Be) and divertor (CFC W coated and bulk W) have been designed to maximise their power handling capability. During the last experimental campaign (October 2010 to July 2011) this capability has been assessed and even challenged in the case of the beryllium wall. The Be limiters are composed of highly shaped, castellated tiles. They are optimised for a range of scrape-off layer (SOL) power decay length 5 < lq,design < 20mm. Its power handling capability (19MW/m2s1/2), predicted with a simple model, has been proven to be robust by the experiments despite unexpected power loads pattern. However, this capability has been pushed to its limit leading to Be melt events, which revealed that the power load is toroidally asymmetric. The toroidal asymmetry could be explained by a misalignment of the limiters by 1mm. The protection system of the ILW has now been partially commissioned and the main chamber protection was operational. It did not prevent melt events mainly because the protection. The bulk W divertor target performed as predicted. Operations were constrained by: 1) an energy load limit of 60MJ per stack ( 60MJ/m2), and 2) the limited number of cycles of the surface temperature above 1200oC in order to prevent thermal fatigue. This latter limit has been exceeded about 300 times and no signs of damage or thermal fatigue have been observed by the photogrammetric survey.

To present in vivo, human validation of a previously proposed method to measure key pulmonary parameters related to lung microstructure and physiology. Some parameters, such as blood-air barrier thickness, cannot be measured readily by any other noninvasive modality.Healthy volunteers (n = 12) were studied in 1.5T and 3T whole body human scanners using hyperpolarized xenon. Xenon uptake by lung parenchyma and blood was measured using a chemical shift saturation recovery sequence. Both dissolved-xenon peaks at 197 ppm and 217-218 ppm were fitted against a model of xenon exchange (MOXE) as functions of exchange time. Parameters related to lung function and structure can be obtained by fitting to this model.The following results were obtained from xenon uptake (averaged over all healthy volunteers): surface-area-to-volume ratio = 210 ± 50 cm(-1) ; total septal wall thickness = 9.2 ± 6.5 μm; blood-air barrier thickness = 1.0 ± 0.3 μm; hematocrit = 27 ± 4%; pulmonary capillary blood transit time = 1.3 ± 0.3 s, in good agreement with literature values from invasive experiments. More detailed fitting results are listed in the text.The initial in vivo human results demonstrate that our proposed methods can be used to noninvasively determine lung physiology by simultaneous quantification of a few important pulmonary parameters. This method is highly promising to become a versatile screening method for lung diseases.

The first wall of RFX-mod is entirely made of polycrystalline Graphite that completely covers the Inconel vacuum vessel. The full Carbon first wall assured very safe operation also at the highest feasible plasma current of 2 MA, when strong localized plasma-wall interaction events can cause thermal load to the wall up to tens of MW/m 2 . On the other hand, due to the high retention of H2, the graphite wall dramatically affected density control during operation and recently the possibility to move to metal plasma facing components is under study. The material chosen for RFX is Tungsten, but bulk tiles are not usable since theirmuch higher weight with respect to graphite ones would imply a major modification of the mechanical structure of RFX-mod. For this reason, a research activity has started in order to determinewhich is the deposition technique that will assure the Tungsten coating on Graphite tiles with the best resistance to the interaction with RFX plasmas. The coating techniques under test are Plasma Spray and different types of Plasma Vapour Deposition, with coating thicknesses in the range of hundreds and tens of microns respectively. A manipulator has been setup in order to allow the insertion of large coated samples up to the envelope of the first wall of RFX-mod, and the poloidal section where the manipulator is installed has been equipped with IR piro-bolometer and fast camera for the measure of thermal load during exposure and spectroscopic monitors for the evaluation of erosion. The samples temperature is also measured by means of integrated thermocouples. Finally, the manipulator comprises a built-in Thermal Desorption Spectroscopy diagnostic, that will allow in-situ studies of gas retention. The exposure of samples to cyclic heath loads has also been done. The characterization of the coating after exposure both to RFX plasma and cyclic heating was essentially based on SEM imaging of the surface and the first results of these studies are the subject of this contribution.

Tungsten coatings with molybdenum interlayer deposited on carbon-fibre reinforced carbon (CFC) substrates were selected as the first wall material for the divertor in the Wall Project at Joint European Torus (similar to the International Thermonuclear Experimental Reactor). For such a layered structure, diffusion of carbon from the CFC substrate towards the Mo and W deposits is expected during the operation of the reactor. As both molybdenum and tungsten form stable carbides, brittle compounds may form at the interface, thus strongly affecting the thermomechanical performance of the coated tiles. For the purpose of prediction of the operation time of such coated tiles, carbon diffusion and carbide formation kinetics need to be determined. In the present study, W/Mo/CFC samples were subjected to heat treatment at 1470 K for various annealing times. The Focused Ion Beam technique was used for sample preparation for electron microscopy examinations. Transmission electron microscopy observations supported with diffraction pattern analyses revealed the both W 2 C and WC carbides in the W coating, as well as that of Mo 2 C carbide in the Mo layer. The results were used to estimate the kinetics of coatings degradation.

This paper presents scientific and technical issues related to the development of erosion-deposition diagnostic tools for JET operated with the ITER-Like Wall: beryllium and tungsten marker tiles and several types of wall probes installed in the main chamber and in the divertor. Markers tiles are the standard limiter and divertor components additionally coated first with a thin sandwich of Ni-Be and Mo-W for, beryllium and tungsten markers, respectively. Both types of markers are embedded in regular arrays of limiter and divertor tiles. Coated W-Be probes are also inserted in the Be-covered Inconel cladding tiles on the central column. Other types of erosion-deposition diagnostic tools are: rotating collectors, deposition traps, louver clips, quartz microbalance and mirrors for the First Mirror Test at JET for ITER. The specific role of these tools is discussed in detail.

When a sulphur bearing gas is added to the nitrogen– hydrogen atmosphere used in a plasma thermochemical treatment, a nitrocarburising process can be performed because of the contribution from the carbon in the steel. In the present work, H2S has been used to introduce sulphur species into the discharge atmosphere. The sulphur promotes the nucleation of the 8 phase. A compound layer of thickness 30–45 μm with a duplex structure can be produced by this procedure on plain carbon steel and low alloy steel substrates. The outer zone (10–12 μm) is pure e phase and the innermost zone consists essentially of γ’ phase. The influence of the gas composition, temperature, and duration of the treatment on the microhardness profiles and thickness of the compound layer has been investigated. Wear tests, using a plain carbon steel substrate, revealed significantly better wear behaviour of the sulphur bearing nitrocarburised specimens, compared with materials treated by conventional plasma nitriding.

A new deposition method, by combining standard magnetron sputtering and ion implantation, has been developed. Some characteristics of the layers produced by this method have been investigated in comparison with the standard TiN coating obtained by conventional magnetron sputtering. The new coatings have a hardness of ∼5000 HV0.04, a thickness up 15 μm and a structure close to Ti2N. The width of the layer–substrate interface is significantly larger than usual and this ensures very good adhesion.

Hyperpolarized xenon-129 has the potential to become a noninvasive contrast agent for lung MRI. In addition to its utility for imaging of ventilated airspaces, the property of xenon to dissolve in lung tissue and blood upon inhalation provides the opportunity to study gas exchange. Implementations of imaging protocols for obtaining regional parameters that exploit the dissolved phase are limited by the available signal-to-noise ratio, excitation homogeneity, and length of acquisition times. To address these challenges, a 32-channel receive-array coil complemented by an asymmetric birdcage transmit coil tuned to the hyperpolarized xenon-129 resonance at 3 T was developed. First results of spin-density imaging in healthy subjects and subjects with obstructive lung disease demonstrated the improvements in image quality by high-resolution ventilation images with high signal-to-noise ratio. Parallel imaging performance of the phased-array coil was demonstrated by acceleration factors up to three in 2D acquisitions and up to six in 3D acquisitions. Transmit-field maps showed a regional variation of only 8% across the whole lung. The newly developed phased-array receive coil with the birdcage transmit coil will lead to an improvement in existing imaging protocols, but moreover enable the development of new, functional lung imaging protocols based on the improvements in excitation homogeneity, signal-to-noise ratio, and acquisition speed.

Purpose: To implement and characterize a single-breath xenon transfer contrast (SB-XTC) method to assess the fractional diffusive gas transport F in the lung: to study the dependence of F and its uniformity as a function of lung volume; to estimate local alveolar surface area per unit gas volume SA/VGas from multiple diffusion time measurements of F; to evaluate the reproducibility of the measurements and the necessity of B1 correction in cases of centric and sequential encoding. Materials and Methods: In SB-XTC three or four gradient echo images separated by inversion/saturation pulses were collected during a breath-hold in eight healthy volunteers, allowing the mapping of F (thus SA/VGas) and correction for other contributions such as T1 relaxation, RF depletion and B1 inhomogeneity from inherently registered data. Results: Regional values of F and its distribution were obtained; both the mean value and heterogeneity of F increased with the decrease of lung volume. Higher values of F in the bases of the lungs in supine position were observed at lower volumes in all volunteers. Local SA/VGas (with a mean ± standard deviation of SA/VGas = 89±30 cm−1) was estimated in vivo near functional residual capacity. Calibration of SB-XTC on phantoms highlighted the necessity for B1 corrections when k-space is traversed sequentially; with centric ordering B1 distribution correction is dispensable. Conclusion: The SB-XTC technique is implemented and validated for in vivo measurements of local SA/VGas. J. Magn. Reson. Imaging 2013;37:457–470. © 2012 Wiley Periodicals, Inc.

Hyperpolarized xenon-129 is a noninvasive contrast agent for lung MRI, which upon inhalation dissolves in parenchymal structures, thus mirroring the gas-exchange process for oxygen in the lung. Multiple-exchange-time xenon polarization transfer contrast (MXTC) MRI is an implementation of the XTC MRI technique in four dimensions (three spatial dimensions plus exchange time). The aim of this study was to evaluate the sensitivity of MXTC MRI for the detection of microstructural deformations of the healthy lung in response to gravity-induced tissue compression and the degree of lung inflation. MXTC MRI was performed in four rabbits and in three healthy human volunteers. Two lung function parameters, one related to tissue- to alveolar-volume ratio and the other to average septal-wall thickness, were determined regionally. A significant gradient in MXTC MRI parameters, consistent with gravity-induced lung tissue deformation in the supine imaging position, was found at low lung volumes. At high lung volumes, parameters were generally lower and the gradient in parameter values was less pronounced. Results show that MXTC MRI permits the quantification of subtle changes in healthy lung microstructure. Further, only structures participating in gas exchange are represented in MXTC MRI data, which potentially makes the technique especially sensitive to pathological changes in lung microstructure affecting gas exchange.

Despite a myriad of technical advances in medical imaging, as well as the growing need to address the global impact of pulmonary diseases, such as asthma and chronic obstructive pulmonary disease, on health and quality of life, it remains challenging to obtain in vivo regional depiction and quantification of the most basic physiological functions of the lung—gas delivery to the airspaces and gas uptake by the lung parenchyma and blood—in a manner suitable for routine application in humans. We report a method based on MRI of hyperpolarized xenon-129 that permits simultaneous observation of the 3D distributions of ventilation (gas delivery) and gas uptake, as well as quantification of regional gas uptake based on the associated ventilation. Subjects with lung disease showed variations in gas uptake that differed from those in ventilation in many regions, suggesting that gas uptake as measured by this technique reflects such features as underlying pathological alterations of lung tissue or of local blood flow. Furthermore, the ratio of the signal associated with gas uptake to that associated with ventilation was substantially altered in subjects with lung disease compared with healthy subjects. This MRI-based method provides a way to quantify relationships among gas delivery, exchange, and transport, and appears to have significant potential to provide more insight into lung disease.