Ultralong Spin Lifetime in Light Alkali Atom Doped Graphene

Today's great challenges of energy and informational technologies are addressed with a singular compound, Li- and Na-doped few-layer graphene. All that is impossible for graphite (homogeneous and high-level Na doping) and unstable for single-layer graphene works very well for this structure. The transformation of the Raman G line to a Fano line shape and the emergence of strong, metallic-like electron spin resonance (ESR) modes attest the high level of graphene doping in liquid ammonia for both kinds of alkali atoms. The spin-relaxation time in our materials, deduced from the ESR line width, is 6-8 ns, which is comparable to the longest values found in spin-transport experiments on ultrahigh-mobility graphene flakes. This could qualify our material as a promising candidate in spintronics devices. On the other hand, the successful sodium doping, this being a highly abundant metal, could be an encouraging alternative to lithium batteries.

P1825 Myocardial bridging and coronary artery disease in hypertrophic cardiomyopathy: a matched case control study

Funding Acknowledgements

None.

Introduction

The etiology of chest pain in hypertrophic cardiomyopathy (HCM) is diverse and includes coronary artery disease (CAD) as well as HCM-specific causes. Myocardial bridging (MB) has been associated with HCM, chest pain, and accelerated atherosclerosis. To investigate differences in the presence of MB and CAD, we compared HCM patients with age-, gender- and CAD pre-test probability (PTP)-matched outpatients presenting with chest pain.

Methods

We studied 84 HCM patients who underwent cardiac computed tomography and compared these with 168 matched controls (age 54 ± 11 years, 70% men, PTP 12% [5%–32%]). MB, calcium score, plaque morphology and presence and extent of CAD were assessed for each patient. Linear mixed models were used to assess differences between cases and controls.

Results

Differences between HCM patients and controls are described in the table. In summary, MB was more often seen in HCM patients (50% vs. 25%, p < 0.001), who were also more likely to have >1 segment affected (14% vs. 2%, p < 0.05). In the HCM group, MB was associated with pathogenic mutation status. Calcium score and the presence of obstructive CAD were similar in both groups (9 [0-225] vs. 4 [0-82] and 18% vs. 19%; p > 0.05 for both).

Conclusion

MB was twice as prevalent in the HCM group. However, in a matched analysis, the prevalence and extent of CAD was equal among patients with and without HCM. These finding illustrate that despite a higher prevalence of MB, the prevalence of CAD is similar between groups, also demonstrating satisfactory performance of pre-test risk prediction in HCM patients.

Assessment of CAD by CT HCM group(n = 84) Control group (n = 168) p-value Agatston score 9 [0-225] 4 [0-82] 0.22 No. of pts with score* 0.07 0-399 31 (89%) 149 (91%) >400 8 (11%) 15 (9%) Obstructive CAD 15 (18%) 32 (19%) 0.82 No. of pts with MB 42 (50%) 42 (25%) <0.001 No. of vessels with MB <0.001 1 34 (40%) 39 (23%) 2 8 (10%) 3 (2%) No. of pts with >1 segment with MB 12 (14%) 4 (2%) <0.001 Abbreviations CAD = Coronary artery disease, MB = Myocardial bridging, pts = patients *Only measured in 73/84 HCM patients and in 164/168 control patients

P802 Delayed time to peak left ventricular outflow tract velocity is associated with symptomatic status in patients with hypertrophic obstructive cardiomyopathy

Funding Acknowledgements

None.

The presence and magnitude of left ventricular outflow tract (LVOT) obstruction in hypertrophic obstructive cardiomyopathy (HOCM) patients is weakly associated with presence of symptoms. The factors underlying this are not well understood. We hypothesize that time to peak velocity (TPV) of LVOT flow is associated with symptomatic status.

We included 136 HOCM patients (58% men, mean age 55 ± 14 years) with peak gradients ≥30 mmHg at rest or during Valsalva without aortic valve stenosis. At rest and during Valsalva, continuous wave Doppler tracings from 3 consecutive beats were used to assess peak velocity (PV), left ventricular ejection time (LVET) and TPV, which was defined as the time interval between the onset of flow over the LVOT and the moment of PV. Differences were compared between asymptomatic and symptomatic patients (defined as New York Heart Association class I vs. II-IV). The relation between symptom status and TPV was investigated using logistic regression models. A random sample of 20 patients was examined by 2 observers and reproducibility was assessed using the intraclass correlation coefficient (ICC).

Symptomatic patients were more often female (table) and had significantly higher mean TPV values (figure). In multivariable logistic regression models, TPV was an independent predictor of symptomatic status after correction for PV, LVOT diameter, heart rate and age (odds ratio 1.02 per 1 ms, p < 0.001). The ICC was 0.99 with a mean difference of 0.28 ± 8.5 ms.

Delayed TPV is associated with symptomatic status in HOCM patients, after adjustment for heart rate, peak velocity, LVOT diameter and age, and is an easily measured echocardiographic variable with excellent inter-reader reproducibility. The clinical implications of delayed TPV, particularly in the context risk prediction and clinical decision making, remain to be determined.

Characteristics per group Asymptomatic HOCM patients n = 47 Symptomatic HOCM patients n = 89 p value Age, y 55 ± 14 55 ± 14 0.99 Male gender 34 (72%) 45 (51%) 0.01 Body mass index, kg/m² 27 ± 5 28 ± 5 0.08 Left atrial diameter, mm 46 ± 7 47 ± 7 0.64 Septal wall thickness, mm 18 ± 4 19 ± 5 0.58 LV outflow tract diameter, mm 22 ± 3 21 ± 3 0.001 Peak velocity, cm/s 403 ± 86 434 ± 79 0.03 LV ejection time, ms 316 ± 44 340 ± 42 0.002 Time to peak velocity, ms 157 ± 32 178 ± 32 <0.001 HOCM = hypertrophic obstructive cardiomyopathy, LV = left ventricular.

Abstract P802 Figure. Time to peak velocity per NYHA class

Effect of body surface area and gender on wall thickness thresholds in hypertrophic cardiomyopathy

BACKGROUND

Family screening for hypertrophic cardiomyopathy (HCM) is based on genetic testing and clinical evaluation (maximal left ventricular wall thickness (MWT) ≥15 mm, or ≥13 mm in first-degree relatives of HCM patients). The aim of this study was to assess the effect of gender and body size on diagnosis of HCM and prediction of clinical outcome.

METHODS

This study includes 199 genotype-positive subjects (age 44 ± 15 years, 50% men) referred for cardiac screening. Gender-specific reference values for MWT indexed by body surface area (BSA), height and weight were derived from 147 healthy controls. Predictive accuracy of each method for HCM-related events was assessed by comparing areas under the receiver operating characteristic curves (AUC).

RESULTS

Men had a higher absolute, but similar BSA- and weight-indexed MWT compared with women (14.0 ± 3.9 mm vs 11.5 ± 3.8 mm, p < 0.05; 6.8 ± 2.1 mm/m² vs 6.6 ± 2.4 mm/m²; 0.17 ± 0.06 mm/kg vs 0.17 ± 0.06 mm/kg, both p > 0.05). Applying BSA- and weight-indexed cut-off values decreased HCM diagnoses in the study group (48% vs 42%; 48% vs 39%, both p < 0.05), reclassified subjects in the largest, lightest and heaviest tertiles (≥2.03 m²: 58% vs 45%; ≤70 kg: 37% vs 46%; ≥85 kg: 53% vs 25%, all p < 0.05) and improved predictive accuracy (AUC 0.76 [95% CI 0.69-0.82] vs 0.78 [0.72-0.85]; and vs 0.80 [0.74-0.87]; both p < 0.05).

CONCLUSIONS

In genotype-positive subjects referred for family screening, differences in MWT across gender are mitigated after indexation by BSA or weight. Indexation decreases the prevalence of HCM, particularly in larger men, and improves the predictive accuracy for HCM-related events.

P5280The impact of background phase offset errors in cardiovascular magnetic resonance phase contrast imaging: a multi-scanner study

Background

Phase contrast (PC) CMR flow measurements (FM) are widely used for blood flow assessment, but they suffer from phase offset errors (POE). Stationary phantom correction limits these inaccuracies, however, this adds scan time. Stationary tissue (ST) correction is an alternative method that does not require additional scanning. The aim of this study was to evaluate the impact of POE, to assess interscanner variation, and to evaluate the ST correction usage.

Methods

We included 166 patients in which both aorta and main pulmonary artery FM were acquired including static gelatin phantom data. Subjects were scanned on three types of 1.5T scanners from the one vendor. Uncorrected and ST corrected FM were compared with phantom corrected FM, our reference value, and corrected for BSA. A difference of >10% in net flow was defined as clinically relevant. Regurgitation fraction was calculated and POE influences were assessed. Regurgitation severity was graded and POE influence on severity grading was assessed.

Results

Of the 166 cases included, the median age was 27 (5–74) years. Overall, the median difference between no corrected and phantom corrected FM was ≤6%, however, with a wide range of over- and underestimation (−155%–78% change) (figure). ST correction resulted in larger differences compared to no correction (p<0.01). Clinically significant differences were seen in 19% of all FM with no correction and in 30% of with ST correction (p<0.01). Furthermore, there were significant differences between scanners (no correction 10%, p<0.01; ST correction, p<0.01). Regurgitation severity indexing changed in 38 (11%) cases with no correction and in 48 (48%) with ST correction.

Magnitude of flow change with and without offset corrections (n=332) Flow (ml/m2) Δ no correction and phantom correction (%) Δ ST correction and phantom correction (%) Clinically significant difference (>10%) Mean ± SD Median IQR Range Median IQR Range No correction, N (%) ST correction , N (%) MRI 1 (n=126) 50±12 3 0 to 6 −8 to 30 5 −3 to 9 −26 to 28 13 (10%) 34 (27%) MRI 2 (n=102) 48±13 −2 −15 to 6 −155 to 78 5 −3 to 11 −74 to 52 50 (49%) 50 (49%) MRI 3 (n=104) 48±12 −1 −1 to 0 −7 to 14 2 −2 to 5 −39 to 29 1 (1%) 16 (15%) Total (n=332) 49±12 0 −2 to 4 −155 to 78 3 −2 to 8 −74 to 52 64 (19%) 100 (30%)

Conclusion

Background POE have a significant impact on flow quantification and regurgitation severity. Unexpectedly, background correction using ST correction worsens accuracy compared to no correction. POE vary greatly between scanners. Therefore, careful assessment of FM at each scanner is essential to determine if routine phantom scanning is necessary.

P1244Survival after septal myectomy in male and female patients with hypertrophic obstructive cardiomyopathy

In recent years, studies have debated the impact of gender on the presentation and clinical course of HCM, with research showing that at time of myectomy, women are older, have worse diastolic function and more advanced cardiac remodeling. The clinical impact of these differences is unknown.

We included 221 HCM patients (57% men) who underwent septal myectomy and are followed in our center. Time to treatment was calculated in relation to symptom onset. Pre- and post-operative clinical and echocardiographic data were collected. Gender differences were assessed at baseline and in survival analyses for the composite endpoint of all-cause mortality, cardiac transplantation, re-intervention and aborted sudden cardiac death.

Women were older at time of myectomy, but time until treatment was similar (table). Pre-operative echocardiographic indices were comparable among groups, but were significantly higher in women when correcting for body surface area. At three months, no differences were found in clinical and echocardiographic results. After 6.1 [2.9–10.1] years, 24% of women and 23% of men had reached the composite endpoint (p=0.30, figure).

Gender comparison pre- and post-myectomy Men (n=125) Women (n=96) p value Age 49±14 54±17 0.02 Maximal wall thickness, mm 19.9±4.7 19.8±5.8 0.97 Indexed maximal wall thickness, mm/m2 9.8±2.5 11.5±4.5 0.001 Left atrial diameter, mm 48.1±7.3 45.9±7.3 0.06 Indexed left atrial diameter, mm/m2 23.5±3.5 26.5±7.5 0.002 LV end-diastolic diameter, mm 45.4±7.6 42.8±5.6 0.04 Indexed LV end-diastolic diameter, mm/m2 22.1±3.7 23.6±3.0 0.02 Gradient reduction, %* 75.1±25.0 72.9±28.6 0.63 Improvement in symptoms*† 97 (95%) 64 (89%) 0.34 MWT = maximal wall thickness; LV = left ventricle. *At three months follow-up; †Defined as a reduction of ≥1 NYHA class, measured in 102 men and 72 women.

Survival after myectomy

Although women present later in life and seem to have more advanced disease at time of myectomy, time to treatment is similar and survival after myectomy is excellent for both men and women.

Surface chemistry of 2,3-dibromosubstituted norbornadiene/quadricyclane as molecular solar thermal energy storage system on Ni(111)

Dwindling fossil fuels force humanity to search for new energy production routes. Besides energy generation, its storage is a crucial aspect. One promising approach is to store energy from the sun chemically in strained organic molecules, so-called molecular solar thermal (MOST) systems, which can release the stored energy catalytically. A prototypical MOST system is norbornadiene/quadricyclane (NBD/QC) whose energy release and surface chemistry need to be understood. Besides important key parameters such as molecular weight, endergonic reaction profiles, and sufficient quantum yields, the position of the absorption onset of NBD is crucial to cover preferably a large range of sunlight's spectrum. For this purpose, one typically derivatizes NBD with electron-donating and/or electron-accepting substituents. To keep the model system simple enough to be investigated with photoemission techniques, we introduced bromine atoms at the 2,3-position of both compounds. We study the adsorption behavior, energy release, and surface chemistry on Ni(111) using high-resolution X-ray photoelectron spectroscopy (HR-XPS), UV photoelectron spectroscopy, and density functional theory calculations. Both Br₂-NBD and Br₂-QC partially dissociate on the surface at ∼120 K, with Br₂-QC being more stable. Several stable adsorption geometries for intact and dissociated species were calculated, and the most stable structures are determined for both molecules. By temperature-programmed HR-XPS, we were able to observe the conversion of Br₂-QC to Br₂-NBD in situ at 170 K. The decomposition of Br₂-NBD starts at 190 K when C-Br bond cleavage occurs and benzene and methylidene are formed. For Br₂-QC, the cleavage already occurs at 130 K when cycloreversion to Br₂-NBD sets in.

Surface chemistry of 2,3-dibromosubstituted norbornadiene/quadricyclane as molecular solar thermal energy storage system on Ni(111)

Dwindling fossil fuels force humanity to search for new energy production routes. Besides energy generation, its storage is a crucial aspect. One promising approach is to store energy from the sun chemically in strained organic molecules, so-called molecular solar thermal (MOST) systems, which can release the stored energy catalytically. A prototypical MOST system is norbornadiene/quadricyclane (NBD/QC) whose energy release and surface chemistry need to be understood. Besides important key parameters such as molecular weight, endergonic reaction profiles, and sufficient quantum yields, the position of the absorption onset of NBD is crucial to cover preferably a large range of sunlight's spectrum. For this purpose, one typically derivatizes NBD with electron-donating and/or electron-accepting substituents. To keep the model system simple enough to be investigated with photoemission techniques, we introduced bromine atoms at the 2,3-position of both compounds. We study the adsorption behavior, energy release, and surface chemistry on Ni(111) using high-resolution X-ray photoelectron spectroscopy (HR-XPS), UV photoelectron spectroscopy, and density functional theory calculations. Both Br₂-NBD and Br₂-QC partially dissociate on the surface at ∼120 K, with Br₂-QC being more stable. Several stable adsorption geometries for intact and dissociated species were calculated, and the most stable structures are determined for both molecules. By temperature-programmed HR-XPS, we were able to observe the conversion of Br₂-QC to Br₂-NBD in situ at 170 K. The decomposition of Br₂-NBD starts at 190 K when C-Br bond cleavage occurs and benzene and methylidene are formed. For Br₂-QC, the cleavage already occurs at 130 K when cycloreversion to Br₂-NBD sets in.

Azimuthal Harmonics in Small and Large Collision Systems at RHIC Top Energies

The first (v_{1}^{fluc}), second (v_{2}), and third (v_{3}) harmonic coefficients of the azimuthal particle distribution at midrapidity are extracted for charged hadrons and studied as a function of transverse momentum (p_{T}) and mean charged particle multiplicity density ⟨N_{ch}⟩ in U+U (sqrt[s_{NN}]=193  GeV), Au+Au, Cu+Au, Cu+Cu, d+Au, and p+Au collisions at sqrt[s_{NN}]=200  GeV with the STAR detector. For the same ⟨N_{ch}⟩, the v_{1}^{fluc} and v_{3} coefficients are observed to be independent of the collision system, while v_{2} exhibits such a scaling only when normalized by the initial-state eccentricity (ϵ_{2}). The data also show that ln(v_{2}/ϵ_{2}) scales linearly with ⟨N_{ch}⟩^{-1/3}. These measurements provide insight into initial-geometry fluctuations and the role of viscous hydrodynamic attenuation on v_{n} from small to large collision systems.

Determining the minimal clinically important difference for the PEmbQoL questionnaire, a measure of pulmonary embolism-specific quality of life

Essentials The minimal clinically important difference (MCID) for PEmbQoL has not yet been determined. We estimated the MCID for PEmbQoL and its subscales via anchor- and distribution-based approaches. Our results indicate that MCID for PEmbQoL appears to be 15 points. Our work enables interpretation of changes or differences in PEmbQoL. SUMMARY: Background Pulmonary embolism (PE) reduces quality of life (QOL). The PEmbQoL questionnaire, a PE-related QOL measure, was recently developed and validated and has been used to quantify disease-specific QOL in clinical studies of patients with PE. However, to date, interpretation of PEmbQoL scores has been limited by a lack of information on the minimal clinically important difference (MCID) of this measure. Objective To determine the MCID for PEmbQoL and its subscales using anchor-based and distribution-based approaches. Methods We analyzed data from the ELOPE Study, a prospective, multicenter cohort study of long-term outcomes after a first episode of acute PE. At baseline and 1, 3, 6 and 12 months after PE, we measured generic QOL (SF-36), PE-specific QOL (PEmbQoL) and dyspnea severity (UCSD Shortness of Breath Questionnaire). We used time-varying repeated-measures mixed-effect models to estimate anchor-based MCID and effect sizes to estimate distribution-based MCID. Results Eighty-two patients participated in this sub-study. Their mean age was 49.4 years, 60% were male and 84% had PE diagnosed in an outpatient setting. Using both anchor- and distribution-based approaches, the MCID for PEmbQoL appears to be 15 points. Based on this MCID, 42%, 59%, 66% and 75% of patients experienced at least one MCID unit of improvement in PEmbQoL from baseline to 1, 3, 6 and 12 months, respectively. Conclusion Our results provide new information on the MCID of PEmbQoL, a PE-specific QOL questionnaire that can be used by researchers and clinicians to measure and interpret changes in PE-specific QOL over time, or as an outcome in clinical trials.

Erratum: Observation of D^{0} Meson Nuclear Modifications in Au+Au Collisions at sqrt[s_{NN}]=200 GeV [Phys. Rev. Lett. 113, 142301 (2014)]

This corrects the article DOI: 10.1103/PhysRevLett.113.142301.

Low-p_{T} e^{+}e^{-} Pair Production in Au+Au Collisions at sqrt[s_{NN}]=200 GeV and U+U Collisions at sqrt[s_{NN}]=193 GeV at STAR

We report first measurements of e^{+}e^{-} pair production in the mass region 0.4<M_{ee}<2.6  GeV/c^{2} at low transverse momentum (p_{T}<0.15  GeV/c) in noncentral Au+Au collisions at sqrt[s_{NN}]=200  GeV and U+U collisions at sqrt[s_{NN}]=193  GeV. Significant enhancement factors, expressed as ratios of data over known hadronic contributions, are observed in the 40%-80% centrality of these collisions. The excess yields peak distinctly at low p_{T} with a width (sqrt[⟨p_{T}^{2}⟩]) between 40 and 60  MeV/c. The absolute cross section of the excess depends weakly on centrality, while those from a theoretical model calculation incorporating an in-medium broadened ρ spectral function and radiation from a quark gluon plasma or hadronic cocktail contributions increase dramatically with an increasing number of participant nucleons. Model calculations of photon-photon interactions generated by the initial projectile and target nuclei describe the observed excess yields but fail to reproduce the p_{T}^{2} distributions.

Beam Energy Dependence of Jet-Quenching Effects in Au+Au Collisions at sqrt[s_{NN}]=7.7, 11.5, 14.5, 19.6, 27, 39, and 62.4 GeV

We report measurements of the nuclear modification factor R_{CP} for charged hadrons as well as identified π^{+(-)}, K^{+(-)}, and p(p[over ¯]) for Au+Au collision energies of sqrt[s_{NN}]=7.7, 11.5, 14.5, 19.6, 27, 39, and 62.4 GeV. We observe a clear high-p_{T} net suppression in central collisions at 62.4 GeV for charged hadrons which evolves smoothly to a large net enhancement at lower energies. This trend is driven by the evolution of the pion spectra but is also very similar for the kaon spectra. While the magnitude of the proton R_{CP} at high p_{T} does depend on the collision energy, neither the proton nor the antiproton R_{CP} at high p_{T} exhibit net suppression at any energy. A study of how the binary collision-scaled high-p_{T} yield evolves with centrality reveals a nonmonotonic shape that is consistent with the idea that jet quenching is increasing faster than the combined phenomena that lead to enhancement.

High-pressure structural and vibrational properties of monazite-type BiPO4, LaPO4, CePO4, and PrPO4

Monazite-type BiPO₄, LaPO₄, CePO₄, and PrPO₄ have been studied under high pressure by ab initio simulations and Raman spectroscopy measurements in the pressure range of stability of the monazite structure. A good agreement between experimental and theoretical Raman-active mode frequencies and pressure coefficients has been found which has allowed us to discuss the nature of the Raman-active modes. Besides, calculations have provided us with information on how the crystal structure is modified by pressure. This information has allowed us to determine the equation of state and the isothermal compressibility tensor of the four studied compounds. In addition, the information obtained on the polyhedral compressibility has been used to explain the anisotropic axial compressibility and the bulk compressibility of monazite phosphates. Finally, we have carried out a systematic discussion on the high-pressure behavior of the four studied phosphates in comparison to results of previous studies.

Beam-Energy Dependence of Directed Flow of Λ, Λ[over ¯], K^{±}, K_{s}^{0}, and ϕ in Au+Au Collisions

Rapidity-odd directed-flow measurements at midrapidity are presented for Λ, Λ[over ¯], K^{±}, K_{s}^{0}, and ϕ at sqrt[s_{NN}]=7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV in Au+Au collisions recorded by the Solenoidal Tracker detector at the Relativistic Heavy Ion Collider. These measurements greatly expand the scope of data available to constrain models with differing prescriptions for the equation of state of quantum chromodynamics. Results show good sensitivity for testing a picture where flow is assumed to be imposed before hadron formation and the observed particles are assumed to form via coalescence of constituent quarks. The pattern of departure from a coalescence-inspired sum rule can be a valuable new tool for probing the collision dynamics.