Reversible Volume Research Articles

Children after kidney transplantation show severe cardiac alterations

Abstract Sudden cardiac death is among the most common causes of death in patients with chronic kidney diseases (CKD) after pediatric kidney transplantation (KTx), but defined diagnostic procedures identifying children at risk are not established. Echocardiographically detectable damage in the context of CKD has been described, but there are few data after KTx in childhood. The aim was to characterize structural and functional cardiac alterations on cardiac MRI (cMRI) and echocardiography in children after KTx and to elucidate the significance of diastolic dysfunction in this special context. 46 KTx recipients (mean age 16.0±3.5 years) and due to missing reference values 46 age- and sex-matched healthy controls were examined with non-contrast cMRI. Native T1 time (nT1), left ventricular mass z-score (LVMIz), ejection fraction (EF), global longitudinal strain (GLS) were measured. KTx recipients underwent comprehensive echocardiography: EF, mitral inflow (E-, A-wave), TDI e', E/e'-ratio, isovolumetric relaxation time (IVRT), pulmonary venous flow (PVFsys, PVFdia), atrial reversal (PVF-AR) and left atrial volume index (LAVI), left ventricular mass z-score (LVMz). Multivariable linear regression analysis (co-variates: age, sex, height) were used to show associations between cMRI and echo parameters. In cMRI KTx recipients had a siginficant higher nT1 than healthy controls (septal: 1198±49ms vs. 1155±23ms, p<0.0001; lateral: 1141±57ms vs. 1109±37ms, p=0.003). In KTx recipients, LVMIz was higher (0.1±1.1g/m2 vs. -0.3±0.7g/m2; p=0.026), GLS was lower than in healthy controls (-19± 2.1% vs. -20.3±2.7%, p=0.01). While based on cMRI 2 patients were diagnosed with left ventricluar hypertrophy (LVH), 11% (n=5) displayed LVH on echo. EF was preserved in all patients. However, in echocardiography, 90% (n=40) of the KTx recipients showed diastolic parameters out of the age-specific normal range (Fig.1) with changes in two or more diastolic parameters in half of the cohort. Associations with septal nT1 on cMRI could be demonstrated for septal E/e´ (ß=8.415, p=0.042), A-wave (ß=1.037, p=0.045), LAVI (ß=3.347, p=0.002) and PVF-AR (ß=2.945, p=0.021); associations with lateral nT1: septal E/e´ (ß=9.590, p=0.045) and LAVI (ß=3.393, p=0.009) (Fig. 2); 7 (15 %) had an elevated nT1 septal, lateral and E/e´ out of the normal range. Young KTx recipients show a high prevalence of diastolic dysfunction with preserved EF. Impaired diastolic function was associated with structural alterations reflecting myocardial fibrosis. Our findings suggest that a large number of children after KTx suffer from heart failure with preserved EF – an entity not yet defined in children but described for adults, in whom it is associated with sudden cardiac death. Further studies are needed to describe the clinical relevance of these findings, which gain explicit importance, as the prognosis of HFpEF in adults is improved by SGLT2i, a treatment option not yet considered in our high-risk patient group.

Modeling Reversible Volume Change in Automotive Battery Cells with Porous Silicon Oxide-Graphite Composite Anodes

Automotive battery manufacturers are working to improve the individual cell and overall pack design by increasing durability, performance, and range, while reducing cost, and active material volume change is a key aspect that needs to be considered during this design process. Recently, silicon oxide-graphite composite anodes are being explored to increase total anode capacity while maintaining a tolerable amount of cell level reversible volume expansion due to the relatively lower reversible volume change of the silicon oxide compared to pure battery grade or metallurgical grade silicon. To predict the blended anode response and contribution to the overall cell volume change, we integrated the mechanical behavior of the individual active materials with the multi-species, multi-reaction model to predict the state-of-lithiation of the active materials in the cell at a given potential. The resulting simulations illustrate the tradeoff in volume change between the silicon oxide and the graphite during cell operation. This type of modeling approach will allow designers to virtually consider the impact of cell level and pack level design changes on overall system mechanical performance for automotive and grid storage applications, namely that relatively small addition of silicon containing materials can drive a significant increase in the volume change at the cell level, as demonstrated by the 5 wt% addition of silicon oxide accounting for half of the overall volume change in the cell.

Constructing and Investigating a Ceria-Based Electro-Chemo-Resistivity Switch

Coupling between an electrochemical reaction and a functional material property has been termed electro-chemo-X, or EC-X, where X can refer to mechanical, optical, magnetic, or thermal properties. Recently, our group has demonstrated a two-terminal electro-chemo-mechanical (ECM) membrane actuator operating under ambient conditions and containing a Ce0.8Gd0.2O1.9 (20GDC) solid electrolyte (SE) layer sandwiched between two Ti oxide/Ce0.8Gd0.2O1.9 (Ti-GDC) nanocomposite thin films. Reducing one nanocomposite film while oxidizing the other was observed to produce reversible volume change thereby driving actuator operation. Here, we use the same electrolyte and nanocomposite layers to further explore the EC-X effect: we present, as proof-of-concept, a functioning, three-terminal, thin film based EC-electrical switching device operating at room temperature.The stacked lamellar structure which comprises the device (Figure 1) was fabricated by first depositing, using magnetron sputtering, a ~200nm thick layer of Ti metal on a sapphire substrate. This was followed by patterning with photolithography and etching, using a commercial, buffered oxide etch solution, thereby creating a 1mm wide channel. The resulting bottom electrode pair ("source" and "drain"), which could be temporarily shorted together when necessary, were subsequently covered by the WB/SE/RV stack, where the same co-sputtered, ~200nm thick Ti-GDC nanocomposite (<40nm grain size; 39at% Ti) was used for both the working body (lower: WB) and the reservoir (upper: RV) layers; a ~400nm thick 20GDC layer served as the SE. Upon WB deposition, the 1mm channel between the source and drain electrodes was filled with the nanocomposite material. The upper electrical contact, a ~200nm Ti layer, covered the RV, and using the same photolithography and etching process already described, the top "gate" electrode was defined. To avoid oxidation of the ion reservoir (RV) surface by atmospheric oxygen during device operation, a ~500 nm thick Ta-oxide layer was deposited by reactive magnetron sputtering and patterned by lift-off techniques.We find that following two hours application of -/+ 6V bias between the "gate" and (temporarily shorted) "source" / "drain" electrodes under ambient conditions, the average change in ohmic resistance of the WB in the 1mm channel upon reversal of electrode bias was determined, by cyclic voltammetry between the source and drain electrodes, to be 6.5 ±1.8Gohm with statistical uncertainty based on at least 3 cycles, 5 samples. Negative "gate" bias produced the lower resistance values. The low resistance state decayed during approx. 24 hours, as monitored by cyclic voltammetry. Raising the temperature above ambient (333K) further reduced resistance. We interpret these observations as follows: Negative bias voltage application to the "gate" produces a gradient of the chemical potential of diffusing oxygen ions at the SE-WB interface. This gradient leads to the injection of ions into the WB, thereby promoting an electrochemical oxidation reaction. The nanocomposite in the 1mm channel decays from the more highly conductive state during approximately twenty-four hours. Reversing the bias polarity extracts ions from the WB, with the opposite results. To complement the findings of the E-field promoted oxidation, we performed annealing at 633K for 23 hours in air of a device which lacked the SE/RV/"gate" electrode/Ta-oxide layers, i.e. the WB was uncovered. We observed an increase of two orders of magnitude in the conductivity of the nanocomposite in the 1mm channel, which then relaxes with time. As a control, the same thermal treatment was conducted under vacuum. In this case no change was observed in channel conductivity.A possible explanation for how oxidation increases the Ti-GDC nanocomposite conductivity may be found in a suitable variant of the space charge model [1, 2]. We note that nanocrystallinity introduces such a high density of interfaces/grain boundaries that total conductivity may become interfacially controlled. Grain boundaries in doped ceria lack long range order and are relatively rich in oxygen vacancies (VO) and Ce3+, which, along with a space charge zone which forms for charge neutrality, produce a blocking effect for ion conduction. Oxidation of Ce3+ => Ce4+ leads to a lowering of total real charge, causing the spatial extent of the space charge zone to shrink as well. Finally, this succeeds in lowering the potential barrier for ion diffusion across the grain boundary, which increases the overall conductivity. Reduction of the Ti-GDC nanocomposite produces the opposite effect.[1] S. K. Kim, S. Khodorov, I. Lubomirsky, S. Kim, Phys Chem Chem Phys 2014, 16, 14961, https://doi.org/10.1039/c4cp01254b[2] S. Kim, J. Maier, J. Elecrochem. Soc. 2002, 149, J73, https://doi.org/10.1149/1.1507597 Figure 1

Novel synthesis of thermoresponsive single-walled carbon nanotubes/poly(N-isopropylacrylamide) hybrids

Poly(N-isopropylacrylamide) (PNIPAM) is one of the most well studied thermoresponsive polymers and its microgels undergo a reversible volume phase transition (VPT) at temperatures close to that of the human body. Coupling this property with the unique optical properties of single-walled carbon nanotubes (SWCNT) in the near infrared (NIR) leads to interesting nanohybrids that could be used as multi-responsive sensors/actuators for biological applications.We show the synthesis of thermoresponsive SWCNT/PNIPAM hybrids using two different non-covalent strategies, preserving the nanotube optical properties such as fluorescence. The first strategy involves the dispersion of the SWCNT in water with sodium dodecyl sulfate (SDS), and subsequent in situ synthesis of PNIPAM microgels inside the SDS coatings around the nanotubes. The second strategy starts with modifying the nanotubes with a pyrene derivative, which in turn is used as the starting point for the in situ polymerization of the PNIPAM microgels, thus ensuring that the polymer grows around the nanotubes. In both cases, we obtain hybrids showing a phase transition at temperatures close to that of the human body, with the absorption and fluorescence spectra of the hybrids in the NIR changing in response to the changing dielectric environment. These systems could be used as actuators/sensors in biological systems.

Modeling Rate Dependent Volume Change in Porous Electrodes in Lithium-Ion Batteries

Automotive manufacturers are working to improve individual cell, module, and overall pack design by increasing the performance, range, and durability, while reducing cost. One key piece to consider during the design process is the active material volume change, its linkage to the particle, electrode, and cell level volume changes, and the interplay with structural components in the rechargeable energy storage system. As the time from initial design to manufacture of electric vehicles decreases, design work needs to move to the virtual domain; therefore, a need for coupled electrochemical-mechanical models that take into account the active material volume change and the rate dependence of this volume change need to be considered. In this study, we illustrated the applicability of a coupled electrochemical-mechanical battery model considering multiple representative particles to capture experimentally measured rate dependent reversible volume change at the cell level through the use of an electrochemical-mechanical battery model that couples the particle, electrode, and cell level volume changes. By employing this coupled approach, the importance of considering multiple active material particle sizes representative of the distribution is demonstrated. The non-uniformity in utilization between two different size particles as well as the significant spatial non-uniformity in the radial direction of the larger particles is the primary driver of the rate dependent characteristics of the volume change at the electrode and cell level.

Impact of surgeon variability on outcomes after total shoulder arthroplasty: an analysis of 2188 surgeons

BackgroundThere has been limited evaluation of surgeon-specific factors on outcomes after total shoulder arthroplasty (TSA). The goals of this study were (1) to determine the impact of surgeon procedural volume, career duration, practice type, and fellowship training on TSA outcomes at 2-year follow-up and (2) to evaluate the relative importance of surgeon variables in relation to patient variables in influencing outcomes. MethodsThe PearlDiver Mariner database was queried to identify all surgeons who performed a minimum of 11 TSA procedures from 2010 to 2018. An Internet search of publicly available data was performed to determine the career duration, practice type, and fellowship training of each surgeon. Multivariate logistic regression models were built to determine the relationship between surgeon-specific variables and 2-year surgical complications and revisions and 90-day readmissions. Variable importance of patient-specific and surgeon-specific factors was determined by the Akaike information criterion increase of these models. ResultsA total of 2188 surgeons who performed 93,122 TSA procedures were identified in this database. Higher reverse TSA surgical volume was associated with fewer surgical complications and revisions, although such a relationship was not observed for anatomic TSA. Revision after anatomic TSA was more common among surgeons who were in their first 5 years of practice. There was a higher risk of surgical complication and readmission among academic surgeons, but this did not equate with a higher risk of revision. The impact of these surgeon-specific factors on outcomes was small in relation to patient-level variables, such as age, sex, and number of medical comorbidities. ConclusionSurgeon procedural volume, career duration, and practice setting influence the surgical complication, revision, and readmission rates after TSA. The impact of surgeon factors was small relative to patient variables, highlighting the importance of patient selection in mitigating adverse outcomes.

Clinical efficacy of different androgen deprivation therapies for prostate cancer and evaluation based on dynamic-contrast enhanced magnetic resonance imaging.

To evaluate the clinical efficacy of different androgen deprivation therapies for prostate cancer (PCa) based on dynamic-contrast enhanced magnetic resonance imaging (DCE-MRI). 104 patients with PCa were studied, all of whom were treated with androgen deprivation therapy. The patients were divided into a continuous group (continuous androgen deprivation therapy) and an intermittent group (intermittent androgen deprivation therapy) by random number table method, 52 cases/group. The therapeutic effect and DCE-MRI indices were compared and the relationship between DCE-MRI indices and clinical efficacy and the evaluation value of therapeutic efficacy were analyzed. The objective response rate (ORR) of the intermittent group was higher than that of the continuous group (p < 0.05), and there was no significant difference in disease control rate (DCR) between the two groups (p > 0.05). After treatment, volume transfer coefficient (Ktrans), reverse transfer constant (Kep), volume fraction (Ve), blood volume (BV), and blood flow (BF) in both groups were lowered, and those in the intermittent group were lower than the continuous group (p < 0.05). Ktrans, Kep, Ve, BF, and BV in the ORR group were lower than those in the non-ORR group (p < 0.05). Ktrans, Kep, Ve, BF, and BV were correlated with the therapeutic effect of PCa (p < 0.05). The AUC value of the combined detection of DCE-MRI indices in evaluating the therapeutic effect of PCa was greater than that of each index alone (p < 0.05). Compared with continuous androgen deprivation therapy, intermittent androgen deprivation therapy has better clinical efficacy in the treatment of PCa, and DCE-MRI indices are related to the treatment efficacy of PCa and have an evaluation value.

A Gd-doped ceria/TiOx nanocomposite as the active layer in a three terminal electrochemical resistivity switch.

Coupling between an electrochemical reaction and a functional material property has been termed electro-chemo-X, or EC-X, where X can refer to mechanical, optical, magnetic or thermal properties. Recently, our group has demonstrated a two-terminal electro-chemo-mechanical (ECM) membrane actuator operating under ambient conditions and containing a Ce0.8Gd0.2O1.9 solid electrolyte layer sandwiched between two Gd-doped ceria/TiOx nanocomposite thin films. Reducing one nanocomposite film while oxidizing the other was observed to produce reversible volume change thereby driving membrane actuator operation. Here, we use the same electrolyte and nanocomposite layer pair (the upper one as the ion reservoir and the lower, as the active layer) to further explore the EC-X effect. We demonstrate the suitability of the nanocomposite for a three-terminal, thin film-based resistivity switch. We find that application of ±6 V (<60 kV/cm) bias to the gate terminal for two hours under ambient conditions changes the nanocomposite conductivity in the channel between the source and drain by at least 40%. When the bias is negative, the active layer remains in a more highly conductive state for approximately twenty-four hours. Impedance spectroscopy and cyclic voltammetry reveal oxygen ion migration taking place between the active layer and the reservoir. X-ray photoelectron spectroscopy indicates that, in the absence of negative gate bias, thermal oxidation of Ce+3 - > Ce+4 is similarly effective in leading to increased nanocomposite conductivity, while reduction produces the opposite effect. With the expectation that the response time can be significantly shortened, the proposed resistivity switch may be suitable for future applications such as sensors, neuromorphic computing or spintronics.

Methods for Quantifying Expansion in Lithium-Ion Battery Cells Resulting from Cycling: A Review

Significant efforts are being made across academia and industry to better characterize lithium ion battery cells as reliance on the technology for applications ranging from green energy storage to electric mobility increases. The measurement of short-term and long-term volume expansion in lithium-ion battery cells is relevant for several reasons. For instance, expansion provides information about the quality and homogeneity of battery cells during charge and discharge cycles. Expansion also provides information about aging over the cell’s lifetime. Expansion measurements are useful for the evaluation of new materials and the improvement of end-of-line quality tests during cell production. These measurements may also indicate the safety of battery cells by aiding in predicting the state of charge and the state of health over the lifetime of the cell. Expansion measurements can also assess inhomogeneities on the electrodes, in addition to defects such as gas accumulation and lithium plating. In this review, we first establish the mechanisms through which reversible and irreversible volume expansion occur. We then explore the current state-of-the-art for both contact and noncontact measurements of volume expansion. This review compiles the existing literature on four approaches to contact measurement and eight noncontact measurement approaches. Finally, we discuss the different considerations when selecting an appropriate measurement technique.

Digital technique to analyze the wear of screw-retained implant supported metal-ceramic dental prostheses and natural tooth as antagonist: a pilot study

The aim of this study was to describe a novel digital technique to analyze the wear of screw-retained implant-supported metal-ceramic dental prostheses and natural tooth as antagonist.Materials and methods Ten patients were consecutively included to rehabilitate partial edentulism by dental implants. Both the screw-retained implant-supported metal-ceramic dental prostheses and the natural tooth as antagonist were submitted to a digital impression through an intraoral scan to generate a Standard Tessellation Language digital file preoperatively (STL1), at 3 months (STL2), and 6 months (STL3) follow-up. Afterwards, an alignment procedure of the digital files (STL1-STL3) was performed on a reverse engineering morphometric software (3D Geomagic Capture Wrap) and volume changes at the screw-retained implant-supported metal-ceramic dental prostheses and the natural tooth as antagonist were analyzed using Student’s t-test. Moreover, Gage R&R statistical analysis was conducted to analyze the repeatability and reproducibility of the digital technique.Results Gage R&R showed a variability attributable to the digital technique of 3.8% (among the measures of each operator) and 4.5% (among operators) of the total variability; resulting repeatable and reproducible, since the variabilities were under 10%. In addition, statistically significant differences were shown at the wear volume (μm3) of both the natural tooth as antagonist (p < 0.0001) and the screw-retained implant-supported metal-ceramic dental prostheses between 3- and 6-months follow-up (p = 0.0002).Conclusion The novel digital measurement technique results repeatable and reproducible to analyze the wear of screw-retained implant-supported metal-ceramic dental prostheses and natural tooth as antagonist.

Electroactive 4D Porous Scaffold Based on Conducting Polymer as a Responsive and Dynamic In Vitro Cell Culture Platform.

In vivo, cells reside in a 3D porous and dynamic microenvironment. It provides biochemical and biophysical cues that regulate cell behavior in physiological and pathological processes. In the context of fundamental cell biology research, tissue engineering, and cell-based drug screening systems, a challenge is to develop relevant in vitro models that could integrate the dynamic properties of the cell microenvironment. Taking advantage of the promising high internal phase emulsion templating, we here designed a polyHIPE scaffold with a wide interconnected porosity and functionalized its internal 3D surface with a thin layer of electroactive conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) to turn it into a 4D electroresponsive scaffold. The resulting scaffold was cytocompatible with fibroblasts, supported cellular infiltration, and hosted cells, which display a 3D spreading morphology. It demonstrated robust actuation in ion- and protein-rich complex culture media, and its electroresponsiveness was not altered by fibroblast colonization. Thanks to customized electrochemical stimulation setups, the electromechanical response of the polyHIPE/PEDOT scaffolds was characterized in situ under a confocal microscope and showed 10% reversible volume variations. Finally, the setups were used to monitor in real time and in situ fibroblasts cultured into the polyHIPE/PEDOT scaffold during several cycles of electromechanical stimuli. Thus, we demonstrated the proof of concept of this tunable scaffold as a tool for future 4D cell culture and mechanobiology studies.

Polyurethane based thin hydrogels for sustained protein delivery

The development of materials that allow the sustained release of therapeutic proteins is the key feature for improving their pharmacokinetics, bioavailability, and dose reduction. In this context, hydrogels are attracting interest, but their design to provide a sustained release profile is still a challenge. Usually, a large mass of polymer is required to prolong the release of the therapeutic agent, involving hydrogels with high thicknesses, which limits their use in some applications. Here, the synthesis of thin thermoresponsive and functionalized hydrogels (tHGs) for sustained protein release is reported to tackle this problem. tHGs were obtained by photo-crosslinking of linear thermoresponsive polyurethanes (PU) based on polyethilenglycol and a functional diol (methyldiethanolamine) that contribute to tertiary amine functionality. These biocompatible tHGs conserved the thermosensitive property of PU, exhibiting a reversible volume change between the swollen and the collapsed state, as a function of temperature. tHGs were able to load the model protein ovalbumin homogenously in their matrix, and sustainably release it during 25 days with a tuneable profile, by changing the PU composition. Finally, this proposal, which combined a very thin delivery film with a sustained protein release, could be a good candidate for its application in ocular therapy.

In situ formation of GeSe nanocrystals in carbon nanofiber network supports for ultra-thick sodium ion storage anodes via enhanced carrier transport

Metallic selenides are considered as a promising class of alternative anodes for sodium ion batteries due to the high capacity conferred by their hybrid sodium storage mechanism. However, the low reversible volume expansion induced by larger size sodium ion storage greatly limits their cycle life, theoretical capacity mining and electrode thickness enhancement. Herein, a germanium selenide/carbon nanofibers (GeSe/CNFs) sodium storage anode is first reported by taking advantage of the encapsulation and dispersion of electrostatic spinning technology, i.e., GeO2 is first mixed with polyacrylonitrile and electrospun to form a wrapped structure, followed by in situ pre-oxidation, carbonization, and selenization. For the optimized electrode, it delivers a high capacity up to 567 mAh g−1 based on the mass of GeSe (320 mAh g−1 based on GeSe/CNFs), reaching > 80% of its theoretical capacity, with a > 2300 cycles cycling stability at 1.0 A g−1. In addition, its capacity barely decays after 700 cycles at near commercial electrode thickness (115 µm, the capacity retention > 47–63% even at the ultrahigh thickness of 187–219 µm). This study opens up new possibilities for the development of Se-based sodium storage anode materials with long life, high capacity and ultra-thick electrode that are expected to meet practical needs.

Non-contact monitoring of glucose concentration and pH by integration of wearable and implantable hydrogel sensors with optical coherence tomography.

Optical coherence tomography (OCT) is a noninvasive imaging technique with large penetration depth into the tissue, but limited chemical specificity. By incorporating functional co-monomers, hydrogels can be designed to respond to specific molecules and undergo reversible volume changes. In this study, we present implantable and wearable biocompatible hydrogel sensors combined with OCT to monitor their thickness change as a tool for continuous and real-time monitoring of glucose concentration and pH. The results demonstrate the potential of combining hydrogel biosensors with OCT for non-contact continuous in-vivo monitoring of physiological parameters.

Numerical and experimental study of oil boom motion response and oil-stopping effect under wave-current action

Little research has been done on the failure of oil booms when wave-current coupling is present. This study investigates the motion response and oil-stopping failure of the oil containment boom experimentally and numerically. The oil containment effect under wave-current and the motion response of the oil containment boom were investigated through experiments. Using CFD software FLUENT for simulation, the study established a multiphase flow analysis model to simulate the oil containment of an oil containment boom and used the volume of fluid method (VOF) to track the oil-water interface. The study compares the experimental and numerical results, which are coincident with each other, and validates the validity of the numerical model. Numerical methods are used to analyze the effects of various working conditions (water flow rate, wave parameter, wave reversal, skirt height, and initial oil spill volume) on the oil containment effect of the oil containment boom. The results show that the presence of waves accelerates the oil containment failure; compared to the wave-current flowing in the same direction, wave-current reversal is better for oil containment, and the initial oil spill volume primarily affects the thickening of the oil layer, which provides an important reference for the design of an effective oil containment boom.

Abstract 18428: Effect of Continuous Positive Airway Pressure on Atrial Remodeling in Patients With Obstructive Sleep Apnea and Paroxysmal Atrial Fibrillation; a Randomized Controlled Trial

Introduction: Obstructive sleep apnea (OSA) is known to cause left atrial (LA) remodeling. The effect of continuous positive airway pressure (CPAP) on LA remodeling in patients with OSA and paroxysmal atrial fibrillation (AF) has not been assessed. Hypothesis: We aimed to assess the impact of CPAP treatment on reverse LA deformation and volume in patients with AF and OSA. Methods: In this secondary analysis of a prospective randomized controlled trial, we screened patients with AF for OSA. The majority of patients were referred for pulmonary vein isolation (PVI). We included AF patients with OSA defined as apnea-hypopnea index (AHI) &gt; 15/h. Patients were randomized to CPAP treatment or standard care. Transthoracic echocardiography was performed to assess atrial remodeling by two-dimensional speckle tracking LA reservoir strain (by AFI LA) and LA volume index (LAVI) in apical 2- and 4-chamber views in sinus rhythm at baseline and at 12 months’ follow-up by an investigator blinded to allocated arm. AF burden was monitored by an implantable loop recorder in all patients. Results: We included 104 patients (62 ±7 years old, 77% men, BMI 30 ± 4) of whom 50 were randomized to CPAP and 54 to standard care. PVI was performed in 83 patients six months after the baseline exam. There was no clear improvement in LA reservoir strain in either group from baseline to follow up (CPAP: 30 ± 8 % vs 32 ± 9 %, p = 0.15; standard care: 28 ± 7 % vs 30 ± 6 %, p = 0.11), and there was no difference between the groups (p=0.41). Similarly, LAVI did not change in the CPAP group (38±8 mL/m 2 vs 36± 10ml/m 2 , p= 0.16) or in the standard care group (39± 10 mL/m 2 vs 37 ± 12 ml/m 2 , p= 0.20) during follow-up, with no difference between the two groups (p =0.62). In patients who underwent PVI, the AF burden decreased in both treatment arms, with no between-group difference (p = 0.69). Conclusions: In AF patients with OSA, treatment with CPAP did not improve reverse left atrial remodeling within 12 months. Although the trial was relatively small, these results suggest that CPAP is unlikely to have a major impact on normalization of LA function after atrial fibrillation ablation in this patient group.

Abstract 12123: Descending Aortic Diastolic Flow Reversal in Aortic Regurgitation: Optimizing Definitions and Assessment on Cardiac Magnetic Resonance

Introduction: Holodiastolic flow reversal (HDR) in the descending aorta (DA) may indicate hemodynamically significant aortic regurgitation (AR). However, the optimal definition and quantification of flow reversal on cardiac magnetic resonance (CMR) is unknown. Methods: We studied 346 chronic AR patients with regurgitant volume (RegVol) ≥30 mL or regurgitant fraction (RegF) ≥30%. The presence of HDR and quantitation of reverse volume in the DA (DA-RVol) was performed by a blinded observer. The threshold for DA-RVol that identified ≥ moderate-severe AR (RegVol ≥45 mL and RegF ≥40%) was established by derivation (50% random sample), validation (50% remaining sample), and ROC curve analysis. Multivariable logistic regression models adjusting for age, gender, NYHA Class, and indexed left ventricular end-diastolic volume were performed to compare HDR and DA-RVol. Results: The median age was 61 (IQR 50-70) years, 79.2% men, and 30.3% with bicuspid aortic valve. The median RegF was 37% (IQR 32-44) and DA-RVol was 12 mL (IQR 5-27). HDR was observed in 150 (43.2%), with 63% sensitivity and 77% specificity for detecting ≥ moderate-severe AR. The threshold of DA-RVol which identified ≥ moderate-severe AR was 17 mL (AUC 0.82, sensitivity 68%, and specificity 87%). The ROC curve analysis revealed a higher AUC for DA-RVol ≥17 mL relative to HDR (0.78 vs 0.70, P &lt;0.001) for predicting ≥ moderate-severe AR. On multivariable analysis models, DA-RVol ≥17 mL was superior to HDR (AUC 0.83 vs 0.80, P =0.008). Conclusion: Quantitation of flow reversal in the descending aorta is a more reliable method to identify hemodynamically significant AR compared to simple presence of holodiastolic flow reversal.

Microvascular proliferation is associated with high tumour blood flow by mpMRI and disease progression in primary prostate cancer

Active angiogenesis may be assessed by immunohistochemistry using Nestin, a marker of newly formed vessels, combined with Ki67 for proliferating cells. Here, we studied microvascular proliferation by Nestin-Ki67 co-expression in prostate cancer, focusing on relations to quantitative imaging parameters from anatomically matched areas obtained by preoperative mpMRI, clinico-pathological features and prognosis. Tumour slides from 67 patients (radical prostatectomies) were stained for Nestin-Ki67. Proliferative microvessel density (pMVD) and presence of glomeruloid microvascular proliferation (GMP) were recorded. From mpMRI, forward volume transfer constant (Ktrans), reverse volume transfer constant (kep), volume of EES (ve), blood flow, and apparent diffusion coefficient (ADC) were obtained. High pMVD was associated with high blood flow (p = 0.008) and low ADC (p = 0.032). High Ktrans, kep, and blood flow were associated with high Gleason score. High pMVD, GMP, and low ADC were associated with most adverse clinico-pathological factors. Regarding prognosis, high pMVD, Ktrans, kep, and low ADC were associated with reduced biochemical recurrence-free- and metastasis-free survival (p ≤ 0.044) and high blood flow with reduced time to biochemical- and clinical recurrence (p < 0.026). In multivariate analyses however, microvascular proliferation was a stronger predictor compared with blood flow. Indirect, dynamic markers of angiogenesis from mpMRI and direct, static markers of angiogenesis from immunohistochemistry may aid in the stratification and therapy planning of prostate cancer patients.

Impact of COVID-19 on inpatient anatomic, reverse and hemi shoulder arthroplasty case volume in the United States

BackgroundDespite known surgical volume reductions in 2020 during the height of the COVID-19 pandemic, no studies have quantified the impact of the pandemic on the number of inpatient anatomic total shoulder arthroplasty (aTSA), reverse total shoulder arthroplasty (rTSA) and hemiarthroplasty cases. The purpose of this study is to analyze the impact of COVID-19 on aTSA, rTSA and hemiarthroplasty case volumes in the United States. MethodsThe Premier Health-care Database was used to identify adults undergoing primary inpatient aTSA, rTSA and hemiarthroplasty from January 2017 to December 2020. Patients undergoing revision total shoulder arthroplasty surgery were excluded. The monthly case volume variance in 2020 was calculated by subtracting the 2017-2019 monthly mean from each respective monthly mean in 2020. Differences in patient and hospital characteristics between subgroups were analyzed using analysis of variance for continuous variables and chi-squared for categorical variables. All statistical analysis was done using STATA (version 17BE; StataCorp LLC, College Station, TX, USA). ResultsA total of 127,496 cases were identified using the Premier Healthcare Database from January 2017 to December 2020. Anatomic TSA accounted for 30.67% of all cases, rTSA represented 63.55%, and hemiarthroplasty accounted for 5.78%. A precipitous decline in cases was observed in March and April of 2020, with aTSA declining by 97%, rTSA declining by 83% and hemiarthroplasty declining by 77% from their prepandemic monthly averages. Cases rebounded in May and peaked by June (rTSA and hemiarthroplasty) or July (aTSA). Cases slightly declined in August, rebounded in September, and declined again at the end of the year. The average length of stay in 2020 was slightly longer for aTSA (1.87 to 2.12 days, P < .0001) and hemiarthroplasty (2.08 to 2.49 days, P = .0021), but slightly shorter for rTSA (1.92 to 1.64 days, P < .0001). We estimated that a total of 29,951 cases were performed in 2020, representing a 7.8% decrease compared with the average from 2017 through 2019, with roughly 2564 patients either delayed or unable to undergo arthroplasty in 2020. ConclusionBased on data from the Premier database, COVID-19 had a negative impact on the case volume of inpatient shoulder replacement (aTSA, rTSA and hemiarthroplasty) surgery in the United States. By the end of 2020, rTSA cases had returned to its monthly average in the years preceding the pandemic, while aTSA and hemiarthroplasty recovered to roughly 75% of their prepandemic case volumes.

Modeling and Analysis of Temperature-Dependent Capacity Degradation in Large Format Lithium-Ion Batteries

The large-format lithium-ion batteries, widely used for electric vehicle applications, are generally characterized by spatial non-uniformities in temperature. The presence of thermal gradients and temperature-dependence of cell parameters are responsible for non-uniform degradation within the battery that leads to poor performance of the battery packs and also poses safety risks. In this work, we aim to develop a detailed physics-based simulation framework to model non-uniform, temperature-dependent capacity degradation within these large format batteries based on the classical pseudo two-dimensional (p2D) battery model. The electrochemical model will be coupled with degradation mechanisms to capture solid-electrolyte interface layer growth, reversible lithium plating, structural disintegration, and volume change within the electrodes on the cell level signatures and usable capacity over charge/discharge cycles. The effects of temperature inhomogeneities will be accounted in the multi-cell simulations at different operating temperatures for individual cells with dynamic currents and temperature and concentration dependent battery parameters as the model inputs.Overall, the primary focus of this study is to capture the effect of spatial temperature variation on battery capacity over cycles and help identify an improved design for the battery module. The model is implemented in an efficient equation-based form for the p2D model and degradation mechanisms with dynamic cell inputs using the mathematical modules in the finite element based solver, COMSOL Multiphysics. This approach enables an easier model development and analysis of the detailed physics and allows an easier implementation of any additional side reaction. The relative contributions of various fade modes have also been compared to understand their competitive interplay over cell cycles. The model predictions are validated with the available experimental data and in-house codes for each case. We believe that this simple yet detailed model can be further developed to be computationally feasible for adoption and implementation in a battery thermal management system.