Hemodynamic and Stress Response After Sound Intervention with Different Headphone Systems: A Double-Blind Randomized Study in Healthy Volunteers Working in the Health Care Sector.

Objectives: Two headphone systems using different sound systems were compared to investigate the effects of a sound intervention on cardiovascular parameters, indicators of stress, and subjective feelings. Methods: One hundred volunteers who work in the health care sector reporting elevated workplace-related stress were enrolled and randomized to a 12-min sound intervention (classical music) with either conventional headphones ("MEZE 99 Classic") or with the same-but internally modified-headphone (called "Lautsaenger"). Cardiovascular parameters were measured with the VascAssist2.0, both before and after sound interventions. In addition, participants were asked to complete questionnaires on burnout risk and emotions/stress. Results: The study population consisted mainly of female participants (n = 83), with the majority being students (42%). Median age was 32.5 years (range 21-71). In terms of cardiovascular parameters, a significant reduction in aortic pulse wave velocity, as measure of arterial stiffness, and heart rate was observed within both treatment arms. Both systolic blood pressure and arterial flow resistance were reduced by sound intervention, while these effects were only documented with Lautsaenger. Treatment groups were comparable in terms of subjective feedback by participants: a significant increase in emotional wellbeing was achieved with both headphone systems. Conclusions: A single short-term sound intervention seems to be able to achieve objective cardiovascular improvements in healthy volunteers reporting subjective symptoms of workplace-related stress, using two different headphone systems. Moreover, significant emotional improvement was reported within both arms. Trial Registration: ISRCTN registry 70947363, date of registration August 13, 2021.

Comparison of Functional and Morphological Estimates of Vascular Age.

BACKGROUND/AIM: Vascular age (VA) is an emerging metric in preventive cardiovascular (CV) medicine. VA can be derived from morphological parameters such as carotid intima-media thickness (CIMT), or functional parameters such as pulse wave analysis (PWA), which celebrates its 100th birthday. This study aimed to investigate whether the results of both approaches are comparable. PATIENTS AND METHODS: On the occasion of the double 100th anniversary of PWA and the Mannheim Clinic, 100 volunteers underwent a) bilateral CIMT assessment using high-resolution ultrasound and b) oscillometric PWA at the brachial forearm site. The respective VAs were calculated using previously published equations. RESULTS: Median age of the participants was 53.6 years (range=39.8-62.6 years), and 56% were female. Median CIMT was 632.5 µm (range=548.8-730.0 µm). Median PWA-derived VA was 55.3 years (36.5-70.5 years). Different values were obtained for CIMT-derived VA, depending on the reference cohort used as calculation basis, ranging from median 43.7 (26.2-59.5 years) to median 64.0 years (43.5-82.1 years). In 46% of the participants divergent VAs were found, that is, the calculated age was higher according to one method and lower according to the other. Correlation analysis revealed a strong dependence of VA (both PWA- and CIMT-derived) and chronological age, as well as an increase in CV risk factors and the detection of plaques with age. CONCLUSION: Different approaches for estimating VA are not comparable and often produce contradictory results. The current methods and their validity must be critically assessed if they are not standardized.

Differential Effects of Sound Intervention and Rest on Cardiovascular Parameters in Cancer Patients: A Randomized Cross-over Trial.

BACKGROUND: Music therapy or sound interventions were shown to confer beneficial effects in patients with cancer for instance in terms of pain or fear relief and improvement of other patient reported outcomes. Cardiovascular parameters, especially heart rate variability (HRV) were found to have prognostic implications in cancer patients. In this trial we aimed to investigate the effects of a sound intervention on cardiovascular parameters compared to rest in patients with cancer. METHODS AND RESULTS: Using a randomized cross-over design, 52 patients (male 13, female 39) with cancer were recruited to receive both a 15-minute sound intervention and a 15-minute rest intervention within 4 weeks with at least a one-week blanking period. Cardiovascular parameters (among others HRV, aortic pulse wave velocity [PWV], augmentation index [Aix], aortic blood pressure [BP], heart rate [HR]) were assessed immediately before (pre) and after (post) the intervention had taken place. HRV (Root mean square of successive RR interval differences [RMSSD, ms]) significantly increased, during sound intervention (median RMSSD pre 24 [range 5-112] vs post 22 [range 9-141], P = .03). Likewise, median PWV, as a direct marker of arterial stiffness, was significantly reduced by sound intervention ([m/s] pre 8.5 [range 5.6-19.6] vs post 8.3 [range 5.6-15.6], P = .04). For both parameters no statistically significant change during rest was observed. HR was lowered by both, rest (P < .0001) and sound intervention (P = .02), with a more pronounced effect by rest. A significant increase in systolic aortic blood pressure was shown by rest ([mmHg] median 101 [range 78-150] vs post median 103 [range 71-152], P = .04) but not during sound intervention (P = .59), while rest intervention led to a decrease in resistance index (pre median 33 [range 13-92] vs post median 32 [11-84], P = .02). CONCLUSION: In comparison with rest, a single sound intervention in patients with cancer improved cardiovascular parameters commonly associated with increased stress levels. Studies with longer follow-up and multiple interventions are warranted. TRIAL REGISTRATION: ISRCTN registry 70947363.

Insights into P2-Type Layered Positive Electrodes for Sodium Batteries: From Long- to Short-Range Order.

P2-type Fe- and Mn-based layered sodium transition metal oxides are promising positive electrode materials for sodium batteries due to their high energy density and low costs of the constituting transition metals. However, poor structural reversibility and fast capacity decay have prevented their breakthrough so far. Herein, the real-time dynamic phase transitions and capacity fading mechanism of the P2 Na0.67Fe0.5Mn0.5O2 positive electrode are revealed by operando X-ray diffraction, operando/ex situ X-ray absorption spectroscopy, neutron powder diffraction, and neutron pair distribution functions. Upon the desodiation process, a layered OP4 phase with long-range order is found as an intermediate state. With further deep desodiation, the formation of a Na-depleted ramsdellite phase with a short coherent length of 30 Å is observed for the first time. However, the transition from OP4 to ramsdellite is considered to be irreversible due to the breakdown of the layered structural characteristics, resulting in poor cycling performance in a variety of Fe-based layered sodium transition metal oxides. This work suggests that stabilizing the crystal structure by substitution or chemical modification can be a favorable strategy to avoid the degradation of positive electrodes and thus to improve the cycling performance.

Multiple coupled resonances in the human vascular tree: refining the Westerhof model of the arterial system.

The human arterial vascular tree can be described by multicompartment models using electrical components. First introduced in the 1960s by Noordergraaf and Westerhof, these hardware-based approaches required several simplifications. We were able to remove the restrictions using modern software simulation tools and improve overall model quality considerably. Whereas the original Westerhof model consisted of 121 Windkessel elements, the refined model has 711 elements and gives realistic pulse waveforms of the aorta and brachial and radial arteries with realistic blood pressures. Moreover, novel insights concerning the formation of the physiological aortic-to-radial transfer function were gained. Its being potentially due to the coupling of many small resonant elements gives new impetus to the discussion of arterial pressure wave reflection. The individualized transfer function derived from our improved model incorporates distinct patient characteristics and can potentially be used for estimation of central blood pressure values. NEW & NOTEWORTHY We were able to find an individualized transfer function giving realistic pulse waveforms and blood pressures using a multicompartment model of the arterial system. Based on the hardware-built Westerhof approach, several simplifications initially introduced in the 1960s could be reversed using software simulation. Overall model quality was improved considerably, and multiple coupled resonances were identified as potential explanation for the formation of the aortic-to-radial transfer function, giving new impetus to the discussion of arterial pressure wave reflection.

Morphological Evolution of High-Voltage Spinel LiNi(0.5)Mn(1.5)O4 Cathode Materials for Lithium-Ion Batteries: The Critical Effects of Surface Orientations and Particle Size.

An evolution panorama of morphology and surface orientation of high-voltage spinel LiNi(0.5)Mn(1.5)O4 cathode materials synthesized by the combination of the microwave-assisted hydrothermal technique and a postcalcination process is presented. Nanoparticles, octahedral and truncated octahedral particles with different preferential growth of surface orientations are obtained. The structures of different materials are studied by X-ray diffraction (XRD), Raman spectroscopy, X-ray absorption near edge spectroscopy (XANES), and transmission electron microscopy (TEM). The influence of various morphologies (including surface orientations and particle size) on kinetic parameters, such as electronic conductivity and Li(+) diffusion coefficients, are investigated as well. Moreover, electrochemical measurements indicate that the morphological differences result in divergent rate capabilities and cycling performances. They reveal that appropriate surface-tailoring can satisfy simultaneously the compatibility of power capability and long cycle life. The morphology design for optimizing Li(+) transport and interfacial stability is very important for high-voltage spinel material. Overall, the crystal chemistry, kinetics and electrochemical performance of the present study on various morphologies of LiNi(0.5)Mn(1.5)O4 spinel materials have implications for understanding the complex impacts of electrode interface and electrolyte and rational design of rechargeable electrode materials for lithium-ion batteries. The outstanding performance of our truncated octahedral LiNi(0.5)Mn(1.5)O4 materials makes them promising as cathode materials to develop long-life, high energy and high power lithium-ion batteries.

Site preference and lattice relaxation around 4d and 5d refractory elements in Ni3Al.

X-ray absorption spectroscopy is employed to investigate site preference and lattice relaxation around Mo, Ru, Hf, W and Re dopants in Ni3Al. The site occupation preference and the measured distances between the refractory elements as dopants and the nearest host atoms are compared with the results of ab initio calculations within the density functional theory. Combined experimental and theoretical results indicate that Mo, Hf, W and Re atoms reside on the Al sublattice in Ni3Al, while Ru atoms occupy the Ni sublattice. A more pronounced lattice relaxation was detected in the case of Hf and Ru doping, with a strong outward relaxation of the nearest Ni and Al atoms.

Evolution of structure and local magnetic fields during crystallization of HITPERM glassy alloys studied by in situ diffraction and nuclear forward scattering of synchrotron radiation.

Evolution of structure and local magnetic fields in (Fe(1-x)Co(x))76Mo8Cu1B15 (HITPERM) metallic glass ribbons with various amounts of Co (x = 0, 0.25, 0.5) were studied in situ using diffraction and nuclear forward scattering of synchrotron radiation. It was found that crystallization of all three glasses proceeds in two stages. In the first stage, bcc (Fe,Co) nanocrystals are formed, while in the second stage additional crystalline phases evolve. For all three glasses, the crystallization temperatures at the wheel side were found to be lower than at the air side of the ribbon. The crystallization temperatures were found to decrease with increasing Co content. The lattice parameters of the bcc nanocrystals decrease up to about 550 °C and then increase pointing to squeezing Mo atoms out of the nanograins or to interface effects between the nanocrystals and the glassy matrix. Nuclear forward scattering enabled separate evaluation of the contributions that stem from structurally different regions within the investigated samples including the newly formed nanocrystals and the residual amorphous matrix. Even minor Co content (x = 0.25) has a substantial effect not only upon the magnetic behaviour of the alloy but also upon its structure. Making use of hyperfine magnetic fields, it was possible to unveil structurally diverse positions of Fe atoms that reside in a nanocrystalline lattice with different numbers of Co nearest neighbours.

Investigation of short-range structural order in Zr69.5Cu12Ni11Al7.5 and Zr41.5Ti41.5Ni17 glasses, using X-ray absorption spectroscopy and ab initio molecular dynamics simulations.

Short-range order has been investigated in Zr69.5Cu12Ni11Al7.5 and Zr41.5Ti41.5Ni17 metallic glasses using X-ray absorption spectroscopy and ab initio molecular dynamics simulations. While both of these alloys are good glass formers, there is a difference in their glass-forming abilities (Zr41.5Ti41.5Ni17 > Zr69.5Cu12Ni11Al7.5). This difference is explained by inciting the relative importance of strong chemical order, icosahedral content, cluster symmetry and configuration diversity.

Synthesis and characterization of nonsubstituted and substituted proton-conducting La(6-x)WO(12-y).

Mixed proton-electron conductors (MPEC) can be used as gas separation membranes to extract hydrogen from a gas stream, for example, in a power plant. From the different MPEC, the ceramic material lanthanum tungstate presents an important mixed protonic-electronic conductivity. Lanthanum tungstate La(6-x)WO(12-y) (with y = 1.5x + δ and x = 0.5-0.8) compounds were prepared with La/W ratios between 4.8 and 6.0 and sintered at temperatures between 1300 and 1500 °C in order to study the dependence of the single-phase formation region on the La/W ratio and temperature. Furthermore, compounds substituted in the La or W position were prepared. Ce, Nd, Tb, and Y were used for partial substitution at the La site, while Ir, Re, and Mo were applied for W substitution. All substituents were applied in different concentrations. The electrical conductivity of nonsubstituted La(6-x)WO(12-y) and for all substituted La(6-x)WO(12-y) compounds was measured in the temperature range of 400-900 °C in wet (2.5% H2O) and dry mixtures of 4% H2 in Ar. The greatest improvement in the electrical characteristics was found in the case of 20 mol % substitution with both Re and Mo. After treatment in 100% H2 at 800 °C, the compounds remained unchanged as confirmed with XRD, Raman, and SEM.

Quantitative structural assessment of heterogeneous catalysts by electron tomography.

We present transmission electron microscope (TEM) tomography investigations of ruthenium-based fuel cell catalyst materials as employed in direct methanol fuel cells (DMFC). The digital three-dimensional representation of the samples not only enables detailed studies on number, size, and shape but also on the local orientation of the ruthenium particles to their support and their freely accessible surface area. The shape analysis shows the ruthenium particles deviate significantly from spherical symmetry which increases their surface to volume ratio. The morphological studies help to understand the structure formation mechanisms during the fabrication as well as the high effectiveness of these catalysts in the oxygen reduction reaction at the cathode side of fuel cells.

Ion-beam-induced collective rotation of nanocrystals.

Vapor-deposited nanocrystalline titanium layers have been irradiated at room temperature with 350-MeV-Au ions up to 4x10;{15} Au/cm;{2}. Bombardment-induced texture changes were determined at the BESSY synchrotron light source. During off-normal irradiation, the nanocrystals undergo grain alignment and rotation up to approximately 90 degrees at the highest ion fluence. At the same time, the whole layer exhibits shear flow very similar to that observed previously in amorphous materials. Below 1x10;{15} Au/cm;{2}, a reversal of the ion incidence angle leads to a back rotation of the grains. These effects are absent or immeasurably small in coarse-grained titanium but have also been found in nanocrystalline TiN and NiO. The observations can be modeled by assuming that grain boundaries behave during ion bombardment like amorphous matter or by assuming a generation of disclination dipoles moving along grain boundaries.