Pressure Phase Research Articles

손 냉각과 압박이 조합된 항암 치료용 장갑이 손의 혈관 수축 및 국소 감각에 미치는 영향

This study investigated the combined effects of wrist compression and hand cooling on cutaneous vasoconstriction of the hands to develop chemotherapy gloves that alleviate side-effects of anti-cancer treatments. Eight healthy young females (23 ± 3 y in age, 162 ± 4 cm in height, 60 ± 8 kg in weight, 22.6 ± 3.0 kg•mSUP-2/SUP in body mass index, 29.0 ± 6.6 % body fat) participated in the following three experimental conditions: cooling only with 14℃ (CO), cooling & intermittent compression (CIC), and cooling & continuous compression (CCC). The results showed 1) no significant differences in finger skin blood flow(%) or finger skin temperature among the three conditions, 2) no significant difference in hand skin temperature between the CO and CCC or CIC conditions, and 3) no significant differences in overall thermal sensation or thermal comfort among the three conditions. However, subjects felt more wrist and hand pressure and tingle sensations in the CIC (pressure phase) and CCC conditions than in the CO condition (P0.001). In conclusion, we did not find any synergistic effects on hand skin vasoconstriction from adding wrist compression to hand cooling, and the pressure and tingling sensations were deteriorated by adding the compression band. Therefore, we suggest cooling the hands at 14oC during cancer treatments, rather than adding compression with cooling.

High pressure phase behavior and thermodynamic modeling of the carbon dioxide + chloroform + globalide system

The high-pressure phase behavior of the ternary system constituted by carbon dioxide + globalide + chloroform was studied. Experiments were conducted applying the synthetic-visual method in a variable-volume view cell at a mass ratios of globalide to chloroform of 0.5:1, 1:1, and 2:1, over a temperature range from 313.15 to 343.15 K, and pressures from 5.17 to 20.25 MPa. Phase transitions of vapor–liquid bubble point (VLE-BP), vapor–liquid dew point (VLE-DP), liquid–liquid (LLE), and vapor–liquid-liquid (VLLE) type were observed. Furthermore, through the P-w diagram, the phase behavior of the ternary system in chloroform free-basis was analyzed between 0.4250 to 0.9735 of carbon dioxide mass composition. It has been observed that high quantities of chloroform lead to lower transition pressures. Moreover, PT-diagrams efficiently displayed that higher pressures are necessary to achieve a single phase medium as temperature rises, which characterize LCST behavior. PR-vdW2 model was used to estimate binary interaction parameters. Additionally, the ternary system was compared with binary systems available in the literature. The data presented in this work provides necessary information for the optimization and improvement of poly(globalide) synthesis in supercritical media.

Raman study of pressure-induced phase transitions in imidazolium manganese- hypophosphite hybrid perovskite

By using Raman spectroscopy, we demonstrate that [IM]Mn(H2POO)3 is a highly compressible material that undergoes three pressure-induced phase transitions. Using a diamond anvil cell we performed high-pressure experiments up to 7.1 GPa, using paraffin oil as the compression medium. The first phase transition, which occurs near 2.9 GPa, leads to very pronounced changes in the Raman spectra. This behavior indicates that this transition is associated with very large reconstruction of the inorganic framework and collapse of the perovskite cages. The second phase transition, which occurs near 4.9 GPa, is associated with subtle structural changes. The last transition takes place near 5.9 GPa and it leads to further significant distortion of the anionic framework. In contrast to the anionic framework, the phase transitions have weak impact on the imidazolium cation. Pressure dependence of Raman modes proves that compressibility of the high-pressure phases is significantly lower compared to the ambient pressure phase. It also indicates that the contraction of the MnO6 octahedra prevails over that of the imidazolium cations and hypophosphite linkers. However, compressibility of MnO6 strongly decreases in the highest pressure phase. Pressure-induced phase transitions are reversible.

Pre-rut behavioural changes in farmed red deer with reference to atmospheric conditions

Red deer (Cervus elaphus) exhibit specific behaviour during the rutting season, which may have an impact on the safety on cervid farms, both due to aggressive interactions between animals and the safety of people staying there, such as staff and tourists. This issue applies especially to stags whose behaviour changes radically, and the correct interpretation of the observed changes is very important. Therefore, the aim of the study was to analyse the pre-rut behaviour of stags and to show the influence of atmospheric conditions on vocalization and other elements of their behaviour, which facilitate determination of the onset of the rutting season. The observations were conducted in August and September of 2017 and 2018. It was shown that lower temperatures, declines in air humidity, increasing atmospheric pressure, and transition of the moon phase towards the full moon resulted in intensification of the vocalization activity in the red deer in the pre-rutting season, which may accelerate the rutting period in the deer males. The number of vocalizations varied between the years and depended on the mean temperature, air humidity, atmospheric pressure, and moon phase in the prerutting and rutting seasons. Through observation of the changing weather conditions, it is possible to predict the time of increased activity of stags and the onset of the rutting period. Predicting the date of mating season in farm breeding, based on daily observations of changes in the behaviour of stags, can be helpful in planning veterinary treatments or selecting the composition of the hinds to be covered by specific stags, which can also contribute to the improvement of their welfare.

Structural transitions at high pressure and metastable phase in Si0.8Ge0.2

The high-pressure behaviour of Si0.8Ge0.2 alloy is explored using in situ Raman spectroscopy, X-ray diffraction techniques and density functional theory (DFT) simulations. High pressure experiments revealed a pressure-induced transition from the stable cubic semiconducting phase (dc- Si0.8Ge0.2) to the tetragonal β-tin metallic phase (β-Si0.8Ge0.2) during compression. This sluggish transition is significantly accelerated at moderate temperature (<300 °C). Upon decompression, successive transitions towards metastable phases are observed. A first transition from the metallic β-Si0.8Ge0.2 toward the rhombohedral r8-Si0.8Ge0.2 phase is observed at 10.3 GPa followed by a partial transition to the body-centered cubic bc8-Si0.8Ge0.2 phase at 2.2 GPa. After releasing the pressure, r8 and bc8 phases coexist at ambient conditions. This transition pathway is similar to that followed by pure silicon and is consistent with the ab initio enthalpy calculations. This phase transition sequence is confirmed by in situ Raman spectroscopy, where signatures of r8 and bc8 phases are observed in the Raman spectra at decompression. An ab initio simulation method is proposed to assign the Raman spectrum of Si0.8Ge0.2 alloy using group theory and projection operators. The exploration of metastable states in these alloys is of major interest both in terms of applications (e.g. optoelectronics) and from a fundamental point of view to better understand the effects of alloying on the physical properties (e.g. vibrational).

Assessment of flaws in cold‐sintered ZnO via acoustic wave speed and attenuation measurements

AbstractThe cold sintering process (CSP) is a low temperature processing technique that utilizes a transient phase to synthesize dense ceramics. However, some CSP parts contain microflaws that arise due to inhomogeneities in pressure, temperature, and transient phase. This work uses 20 MHz ultrasound to verify the presence of defects in CSP ZnO samples of varying densities (84%–97%). Acoustic metrics used in this work include wave speed, which is affected by differences in the effective elastic properties of the medium, and attenuation, which quantifies wave energy loss due to scattering from defects. Wave speed maps were inhomogeneous, suggesting density gradients which were verified with scanning electron microscopy. In addition, it was demonstrated that the pores produced by cold sintering are anisometric, which increases the anisotropy in the elastic properties. High attenuation regions (&gt;300 Np/m) are present in all samples independent of relative density and correspond to defects identified in X‐ray computed tomography (XCT) which were as small as 38 µm in effective diameter. However, some high attenuation spots do not correspond to visible defects in XCT, which suggests the presence of features undetectable with XCT such as residual secondary phases at the grain boundaries.

Data-Driven Prediction of Key Combustion Parameters Based on an Intelligent Diesel Fuel Injector for Large Engine Applications

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;Digital technologies are capable of making a significant contribution to improving large internal combustion engine technology. In particular, methods from the field of artificial intelligence are opening up new avenues. So-called “intelligent” engine components rely on advanced instrumentation and data analytics to create value-added data, which in turn can serve as the basis for applications such as condition monitoring, predictive maintenance and controls. For related components and systems, these data may also allow for novel condition monitoring approaches. This paper describes the use of value-added data from an intelligent diesel fuel injection valve that give detailed information about the injection process for real-time prediction of key combustion parameters such as indicated mean effective pressure, maximum cylinder pressure and combustion phasing. These parameters are usually involved in combustion controls and power unit condition monitoring and normally acquired using in-cylinder pressure indication systems, which are costly and prone to wear. On the one hand, a data-driven model for key combustion parameters based on an intelligent fuel injection valve could replace an indication system. On the other hand, such a model may enable backup functionality and mutual condition monitoring of the fuel injection valve and the indication system. The data required for model building were acquired from a medium-speed four-stroke single-cylinder research engine with a displacement of approximately 15.7 dm&lt;sup&gt;3&lt;/sup&gt;. Different machine learning methods are compared to obtain an accurate yet reliable model for each of the desired combustion parameters. In addition to the value-added injection data, readily available parameters on production engines serve as model inputs (e.g., engine speed, charge air and exhaust gas pressures). Based on the results, the quality of the model predictions is evaluated, and it is assessed whether the approach might be useful for series engine applications.&lt;/div&gt;&lt;/div&gt;

Insulator–metal transition in CrSiTe3 triggered by structural distortion under pressure

van der Waals solids are well known to host remarkable phase diagrams with competing phases, unusual energy transfer processes, and elusive states of matter. Among this class of materials, chalcogenides have emerged as the most flexible and relevant platforms for unraveling charge–structure–function relationships. In order to explore the properties of complex chalcogenides under external stimuli, we measured the far infrared spectroscopic response of CrSiTe3 under extreme pressure–temperature conditions. Analysis of the 368 cm−1 Si–Te stretching mode and the manner in which it is screened by the closure of the indirect gap reveals that the insulator–metal transition takes place immediately after the structural phase transition—once the mixed phase aspect of the lattice distortion is resolved. At the same time, the two-phase region associated with the structural transition widens with decreasing temperature, and the slope of the insulator–metal transition under pressure is consistent with increasing entropy. These trends completely revise the character of the temperature–pressure phase diagram as well as the relationship between the structural and insulator–metal transitions, leading to a critical nexus of activity that may hide a quantum critical point and allow superconductivity to emerge.

Influence mechanism and quantificational evaluation of key factors affecting flutter stability of a transonic fan

The blade flutter stability directly affects the stable operating range of the aero-engine. A few factors related to flutter stability, such as the shock wave, separation flow, inter-blade phase angle (IBPA), and so on, have been found in existing flutter mechanism studies. However, the mechanisms of several factors affecting flutter stability remain to be determined. Taking a transonic fan, NASA rotor 67, as the research object, this paper studies the main factors affecting the blade flutter stability and their influence mechanisms through the unidirectional Fluid-Structure-Interaction (FSI) simulation. The amplitude and phase of unsteady pressure caused by various factors determine the aerodynamic damping distributions of the blade under different operating conditions, which are obtained by the energy method. A quantificational method based on increment proportion is proposed to evaluate the effects of various factors on blade flutter stability by the ratio of the work increment done by each influencing factor to the total work increment, and the flutter stability analysis method is further established. Using this proposed method, it is found that the dominant factors affecting flutter stability before and after design point are inconsistent, which are the shock wave on the suction surface and tip leakage flow, respectively. Furthermore, the mapping relationship of nodal diameter (ND) and flutter stability is also investigated, and the influence mechanism is revealed in this research. The results demonstrate that the nodal diameter affects the amplitude and phase of unsteady pressure by affecting the amplitude and phase of shock wave oscillation, thus affecting the blade flutter stability.

Does Kinesiophobia Affect Spatiotemporal Parameters in Patients with Ankylosing Spondylitis?

Abstract Aim We aimed to examine the effect of kinesiophobia on functional capacity, disease activity, quality of life and spatiotemporal parameters of patients with AS by comparing AS patients with healthy controls. Material and method Our study included 46 patients with ankylosing spondylitis (AS) and 45 healthy controls (HC). Bath Ankylosing Spondylitis Metrology Index (BASMI), Bath Ankylosing Spondylitis Functional Index (BASFI), Ankylosing Spondylitis Quality of Life Scale (ASQoL), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Tampa Kinesiophobia Scale (TKS) scores, Timed Up and Go (TUG) test, maximum plantar pressure and spatiotemporal parameters (total weight transfer, step cycle duration, double-support phase, swing phase, step length, foot angle and cadence) were evaluated. Results Ninety-one individuals (46 AS, 45 HC) (age/sex/BMI) were included in our study. Statistically significant differences were seen between AS and HC groups in TUG, cadence, TKS, maximum pressure, step cycle duration, swing phase, step length, double-support phase, and foot angle measurements (p&lt;0.05). Significant positive correlations existed between TKS and BASMI, BASDAI, BASFI, ASoQ, TUG and foot angle (p&lt;0.05) in AS. Substantial negative correlations were found between TKS and maximum pressure, cadence and swing phase values (p&lt;0.05) in AS. Conclusion Our study is the first in the literature to measure spatiotemporal parameters between patients with AS and HC and evaluate their relationship with kinesiophobia, which was done to the best of our knowledge. We found that patients with AS changed their gait phases by developing a unique pattern and created a more cautious and safe gait model to provide balance and stability. Our study revealed a statistically significant relationship between kinesiophobia and disease activity, functional status, quality of life, cadence, maximum plantar pressure, swing phase, and foot angle. The detailed data we obtained in our study will shed light on gait analysis and research on kinesiophobia in patients with AS. Kinesiophobia should be evaluated in routine gait rehabilitation protocols applied to individuals with AS, and treatment protocols for kinesiophobia should be added if necessary.

Structure and physical properties of predicted MAX phase V2SiC under pressure: A first principle calculation

MAX-phase materials are important for technical applications in different fields, where pressure can change the microstructure and thus the properties of the material. In this paper, the structural, electronic, mechanical, thermodynamic, and optical properties of the new ternary layered ceramic MAX phase V2SiC are investigated under different pressures based on DFT simulations. A greater stiffness along the c-axis than along the a-axis direction and a negative enthalpy of formation confirm the thermodynamic stability of the pressurized phase. Although the band structure is altered under pressure, the metallic properties are retained. The coexistence of its covalent, metallic, and ionic bonds is observed in the charge density diagram. The elastic constants satisfy the Born stability criterion, ensuring mechanical stability under pressurized and unpressurized conditions. The increase in υ from 0.239 to 0.279 indicates that the compound changes from brittle to ductile, with the maximum ductility observed at 20 GPa. Phonon calculations show its kinetic stability, and Helmholtz free energy, enthalpy, entropic specific heat capacity, and Debye temperature are also calculated. Optical properties show that V2SiC is suitable for optoelectronic devices in the visible and UV regions and also as a coating material to reduce the heat from sunlight at high pressures up to 10 GPa. This is the first comprehensive theoretical study of the properties of V2SiC and may provide a reference for future research, the results of which still require subsequent experimental verification.

Oronasal vs Nasal Masks: The Impact of Mask Type on CPAP Requirement, Pharyngeal Critical Closing Pressure (Pcrit), and Upper Airway Cross-Sectional Areas in Patients With OSA

CPAP delivered via an oronasal mask is associated with lower adherence, higher residual apnea-hypopnea index (AHI), and increased CPAP therapeutic pressure compared with nasal masks. However, the mechanisms underlying the increased pressure requirements are not well understood. How do oronasal masks affect upper airway anatomy and collapsibility? Fourteen patients with OSA underwent a sleep study with both a nasal and oronasal mask, each for one-half of the night (order randomized). CPAP was manually titrated to determine therapeutic pressure. Upper airway collapsibility was assessed using the pharyngeal critical closing pressure (Pcrit) technique. Cine MRI was done to dynamically assess the cross-sectional area of the retroglossal and retropalatal airway throughout the respiratory cycle with each mask interface. Scans were repeated at 4cm H2O and at the nasal and oronasal therapeutic pressures. The oronasal mask was associated with higher therapeutic pressure requirements (ΔM ± SEM;+2.6 ± 0.5; P< .001) and higher Pcrit (+2.4 ± 0.5cm H2O; P= .001) compared with the nasal mask. The change in therapeutic pressure between masks was strongly correlated with the change in Pcrit (r2= 0.73; P= .003). Increasing CPAP increased both the retroglossal and retropalatal airway dimensions across both masks. After controlling for pressure and breath phase, the retropalatal cross-sectional area was moderately larger when using a nasal vsan oronasal mask (+17.2mm2; 95%CI, 6.2-28.2, P< .001) while nasal breathing. Oronasal masks are associated with a more collapsible airway than nasal masks, which likely contributes to the need for a higher therapeutic pressure.

Diverse environmental cues drive the size of reproductive aggregation in a rheophilic fish

BackgroundAnimal migrations are periodic and relatively predictable events, and their precise timing is essential to the reproductive success. Despite large scientific effort in monitoring animal reproductive phenology, identification of complex environmental cues that determine the timing of reproductive migrations and temporal changes in the size of reproductive aggregations in relation to environmental variables is relatively rare in the current scientific literature.MethodsWe tagged and tracked 1702 individuals of asp (Leuciscus aspius), a large minnow species, and monitored with a resolution of one hour the size of their reproductive aggregations (counts of sexes present at the breeding grounds standardized by the sum of individuals in the season) over seven breeding seasons using passive integrated transponder tag systems. We examined the size of reproductive aggregations in relation to environmental cues of day number within a reproductive season (intra-year seasonality), water temperature, discharge, hour in a day (intra-day pattern), temperature difference between water and air, precipitation, atmospheric pressure, wind speed and lunar phase. A generalized additive model integrating evidence from seven breeding seasons and providing typical dynamics of reproductive aggregations was constructed.ResultsWe demonstrated that all environmental cues considered contributed to the changes in the size of reproductive aggregations during breeding season, and that some effects varied during breeding season. Our model explained approximately 50% of the variability in the data and the effects were sex-dependent (models of the same structure were fitted to each sex separately, so that we effectively stratified on sex). The size of reproductive aggregations increased unimodally in response to day in season, correlated positively with water temperature and wind speed, was highest before and after the full moon, and highest at night (interacting with day in a season). Males responded negatively and females positively to increase in atmospheric pressure.ConclusionThe data demonstrate complex utilization of available environmental cues to time reproductive aggregations in freshwater fish and their interactions during the reproductive season. The study highlights the need to acquire diverse data sets consisting of many environmental cues to achieve high accuracy of interpretation of reproductive timing.Graphical abstract

Numerical investigation of the effect of fluid pressurization rate on laboratory-scale injection-induced fault slip

The effect of normal stress variations on fault frictional strength has been extensively characterized in laboratory experiments and modelling studies based on a rate-and-state-dependent fault friction formalism. However, the role of pore pressure changes during injection-induced fault reactivation and associated frictional phenomena is still not well understood. We apply rate-and-state friction (RSF) theory in finite element models to investigate the effect of fluid pressurization rate on fault (re)activation and on the resulting frictional slip characteristics at the laboratory scale. We consider a stepwise injection scenario where each fluid injection cycle consists of a fluid pressurization phase followed by a constant fluid pressure phase. We first calibrate our model formulation to recently published laboratory results of injection-driven shear slip experiments. In a second stage, we perform a parametric study by varying fluid pressurization rates to cover a higher dimensional parameter space. We demonstrate that, for high permeability laboratory samples, the energy release rate associated with fault reactivation can be effectively controlled by a stepwise fluid injection scheme, i.e. by the applied fluid pressurization rate and the duration of the constant pressure phase between each successive fluid pressurization phase. We observe a gradual transition from fault creep to slow stick–slip as the fluid pressurization rate increases. Furthermore, computed peak velocities for an extended range of fluid pressurization rate scenarios (0.5 MPa/min to 10 MPa/min) indicate a non-linear (power-law) relationship between the imposed fluid pressurization rate and the peak slip velocities, and consequently with the energy release rate, for scenarios with a fluid pressurization rate higher than a critical value of 4 MPa/min. We also observe that higher pressurization rates cause a delay in the stress release by the fault. We therefore argue that by adopting a stepwise fluid injection scheme with lower fluid pressurization rates may provide the operator with a better control over potential induced seismicity. The implications for field-scale applications that we can derive from our study are limited by the high matrix and fault permeability of the selected sample and the direct hydraulic connection between the injection well and the fault, which may not necessarily represent the conditions typical for fracture dominated deep geothermal reservoirs. Nevertheless, our results can serve as a basis for further laboratory experiments and field-scale modelling studies focused on better understanding the impact of stepwise injection protocols on fluid injection-induced seismicity.

Physical property response of peri-well sediments during cementing of gas hydrate-bearing sediments in conventional oil-gas wells in the South China Sea

In order to investigate the effect of cement slurry penetration during cementing in gas hydrate-bearing sediments. In this study, gas hydrate bearing sediments in Shenhu Area of the South China Sea is taken as the research object, numerical simulation software TOUGH+HYDRATE is used to realistically reproduce the process of cement slurry exothermic and penetration by “continuous segmental simulation.” The physical properties response of sediments near the well wall during cementing under different cementing process parameters and sediment geological parameters are well studied. Results show that the hydration exothermic rate of cement slurry has significant influence on the decomposition degree of hydrate in the penetration area, when it is higher than 0.21 J·(g·s)−1, the hydrate in the penetration range is completely decomposed. The cementing pressure difference affects the cement slurry penetration depth, the extent of sediment pressurization and heat-up, which in turn affects the range of the decomposition zones. In addition, it is helpful to increase pore pressure and hydrate phase equilibrium, but it should be strictly controlled within the window of sediment fracture pressure. Extending the holding time of cementing pressure difference expands the heat-up and decomposition zones, but also delays the onset of hydrate decomposition. Higher saturation prevents the penetration of cement slurry and weakens the diffusion of pore pressure, which causes the shrinkage of the heat-up and decomposition zones, and makes higher pressure in the decomposition zone. The hydrate phase equilibrium environment directly determines the resistance of hydrate sediments to perturbation, with insignificant changes in physical properties in stable sediments. The permeability affects the transport efficiency of pore fluid and expands the heat-up zone and decomposition zone, but also weakens the pore pressure peak of sediment, the increase of permeability from 1 to 100 mD expands the decomposition zone from 1 to 10 cm. The porosity has a less significant effects on the extent of sediment physical properties. This study is a valuable guide and reference for hydrate sediment cementing operations.

Vortex ultrasound catheter for cerebral intravenous sonothrombolysis

One treatment challenge for cerebral venous sinus thrombosis (CVST) is to achieve recanalization within a short period of time (e.g., 30 min) for significant clinical outcomes. Ultrasound-mediated thrombolysis (sonothrombolysis) presents a promising treatment for venous embolism. In this paper, a miniature vortex ultrasound transducer with frequency of 1.8 MHz was developed for sonothrombolysis. A composite transducer with 2-by-2 sub-aperture piezoelectric elements was assembled into a 9-French catheter to generate a physical helical wavefront. The prototyped vortex ultrasound catheter was characterized by measuring the acoustic pressure amplitude and phases, followed by in-vitro- sonothrombolysis tests. It was found that a vortex ultrasound field can be successfully generated by the prototype. The vortex lytic rate was increased by more than 50% compared with the nonvortex lysis with the same acoustic power input. A long (∼7.5 cm), completely occluded in-vitro- 3D model of acute CVST was fully recanalized within 8 min. The unprecedented sonothrombolysis rate was likely attributed to the vortex ultrasound-induced shear stress, which can effectively disrupt acute blood clots. Furthermore, no vessel wall damage over ex-vivo bovine veins was found after the vortex sonothrombolysis treatment.

Confirming the high pressure phase diagram of the Shastry-Sutherland model

A Muon Spin Rotation (µ + SR) study was conducted to investigate the magnetic properties of SrCu2(BO3)2 (SCBO) as a function of temperature/pressure. Measurements in zero field and transverse field confirm the absence of long range magnetic order at high pressures and low temperatures. These measurements suggest changes in the Cu spin fluctuations characteristics above 21 kbar, consistent with the formation of a plaquette phase as previously suggested by inelastic neutron scattering measurements. SCBO is the only known realisation of the Shatry-Sutherland model, thus the ground state mediating the dimer and antiferromagnetic phase is likekly to be a plaquette state.

Regional peak flow as a novel approach to assess regional pulmonary mechanics by electrical impedance tomography: an observational validation study.

Spontaneous breathing efforts during mechanical ventilation are a widely accepted weaning approach for acute respiratory distress syndrome (ARDS) patients. These efforts can be too vigorous, possibly inflicting lung and diaphragm damage. Higher positive end expiratory pressure (PEEP) levels can be used to lower the magnitude of vigorous breathing efforts. Nevertheless, PEEP titrating tools are lacking in spontaneous mechanical ventilation (SMV). Therefore, the aim is to develop an electrical impedance tomography (EIT) algorithm for quantifying regional lung mechanics independent from a stable plateau pressure phase based on regional peak flow (RPF) by EIT, which is hypothetically applicable in SMV and to validate this algorithm in patients on controlled mechanical ventilation (CMV). The RPF algorithm quantifies a cumulative overdistension (ODRPF) and collapse (CLRPF) rate and is validated in a prospective cohort of mechanically ventilated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) patients on CMV. ODRPF and CLRPF are compared with compliance-based cumulative overdistension (ODP500) and collapse (CLP500) rates from the Pulmovista 500 EIT device at multiple PEEP levels (PEEP 10 cmH2O to PEEP 24 cmH2O) in EIT measurements from CMV patients by linear mixed models, Bland-Altman analysis and intraclass correlation coefficient (ICC). Seventy-eight patients were included. Linear mixed models revealed an association between ODRPF and ODP500 of 1.02 (0.98-1.07, P<0.001) and between CLRPF and CLP500 of 0.93 (0.80-1.05, P<0.001). ICC values ranged from 0.78 to 0.86 (P<0.001) for ODRPF and ODP500 and from 0.70 to 0.85 (P<0.001) for CLRPF and CLP500 (PEEP 10 to PEEP 24). The mean bias between ODRPF and ODP500 in these PEEP levels ranged from 0.80% to 4.19% and from -1.31% to 0.13% between CLRPF and CLP500. A RPF approach for quantifying regional lung mechanics showed a moderate to good agreement in coronavirus disease 2019 (COVID-19) related ARDS patients on CMV compared to the compliance-based approach. This, in addition to being independent of a plateau pressure phase, indicates that the RPF approach is a valid method to explore for quantifying regional lung mechanics in SMV.

Theoretical and 27Al NMR Spectroscopic Investigations of Binary Intermetallic Alkaline-Earth Aluminides.

The binary alkaline-earth aluminides AEAl2 (AE = Ca and Sr) and AEAl4 (AE = Ca-Ba) have been synthesized from the elements and investigated via powder X-ray diffraction experiments. CaAl2 adopts the cubic MgCu2-type structure (Fd3̅m), while SrAl2 crystallizes in the orthorhombic KHg2-type (Imma). LT-CaAl4 crystallizes with the monoclinic CaGa4-type (C2/m), while HT-CaAl4, SrAl4, and BaAl4 adopt the tetragonal BaAl4-type structure (I4/mmm). The close structural relation of the two CaAl4 polymorphs was established using a group-subgroup relation in the Bärnighausen formalism. In addition to the room-temperature and normal pressure phase of SrAl2, a high-pressure/high-temperature phase has been prepared using multianvil techniques, and its structural and spectroscopic parameters were determined. Elemental analysis by inductively coupled plasma mass spectrometry showed that no significant impurities with other elements besides the weighed ones are present and the chemical compositions match the synthesized ones. The title compounds have been furthermore investigated by 27Al solid-state magic angle spinning NMR experiments to validate the crystal structure and to gain information about the influence of the composition on the electron transfer and the NMR characteristics. This has also been investigated from a quantum chemical point of view using Bader charges, while the stabilities of the binary compounds in the three phase diagrams (Ca-Al, Sr-Al and Ba-Al) have been studied by calculations of formation energies per atom.

Channelized, distributed, and disconnected: spatial structure and temporal evolution of the subglacial drainage under a valley glacier in the Yukon

Abstract. The subglacial drainage system is one of the main controls on basal sliding but remains only partially understood. Here we expand the analysis of the 8-year dataset of borehole observations on a small, alpine polythermal valley glacier in the Yukon Territory. We presented this dataset in Rada and Schoof (2018), where we described the seasonal evolution of the drainage system and underlined the importance of hydraulic isolation at the glacier bed. These borehole observations constitute a unique dataset, both due to the length of the records and the density of the observations, with up to 157 simultaneously working pressure sensors. Now, to explore the spatial structure of the drainage system and its seasonal progression, we automatically cluster boreholes based on similarities in their water pressure records and follow their evolution through the melt season. Some of these borehole clusters show water pressure variations that suggest they are part of a drainage system connected to the surface meltwater supply, while others show features consistent with hydraulic isolation. The distribution of connected and isolated boreholes suggests that the distributed drainage system we observe comprises a network of small conduits with spacings smaller than the borehole bottom diameter (approximately 25–50 cm). Within these hydraulically connected areas, pressure phase lags, and amplitude attenuation rarely shows the behaviour expected in a diffusive system. This observation suggests that the diffusivity distribution in such areas presents a fine structure at scales smaller than our minimum borehole spacing of 15 m. However, at a glacier-wide scale, we observe that hydraulic connections are ubiquitous in some regions of the bed and permanently absent in others, suggesting large contrasts in diffusivity. Within disconnected areas, boreholes often show small-amplitude water pressure variations associated with horizontal normal stress transfers. Such stress transfers seem to play a more important role than previously considered for controlling the effective pressure distribution at the bed. Through the melt season, the evolution of borehole clusters suggests that the diurnal meltwater supply promotes the growth of the low-efficiency drainage systems found early in the season while stimulating the shrinkage and fragmentation of the more efficient drainage systems that appear later in the season. Therefore, an increase in drainage efficiency is associated with the growth of disconnected areas. Our observations support the traditional view of a distributed drainage system early in the melt season that gradually evolves into a progressively more channelized system. However, the most notable difference is the highly heterogeneous distribution of diffusivity that our results suggest and the robust support for disconnected areas. The extent of disconnected areas could be an essential control of basal speed variations. It is possible that even relatively small disconnected areas could have a disproportionate effect on basal speed.