Main Discharge Research Articles

D‐Electrons of Platinum Alloy Steering CO Pathway for Low‐Charge Potential Li‐CO2 Batteries

AbstractAprotic Li‐CO2 batteries suffer from sluggish solid‐solid co‐oxidation kinetics of C and Li2CO3, requiring extremely high charging potentials and leading to serious side reactions and poor energy efficiency. Herein, we introduce a novel approach to address these challenges by modulating the reaction pathway with tailored Pt d‐electrons and develop an aprotic Li‐CO2 battery with CO and Li2CO3 as the main discharge products. Note that the gas‐solid co‐oxidation reaction between CO and Li2CO3 is both kinetically and thermodynamically more favorable. Consequently, the Li‐CO2 batteries with CoPt alloy‐supported on nitrogen‐doped carbon nanofiber (CoPt@NCNF) cathode exhibit a charging potential of 2.89 V at 50 μA cm−2, which is the lowest charging potential to date. Moreover, the CoPt@NCNF cathode also shows exceptional cycling stability (218 cycles at 50 μA cm−2) and high energy efficiency up to 74.6 %. Comprehensive experiments and theoretical calculations reveal that the lowered d‐band center of CoPt alloy effectively promotes CO desorption and inhibits further CO reduction to C. This work provides promising insights into developing efficient and CO‐selective Li‐CO2 batteries.

An Investigation into the Behavior of Cathode and Anode Spots in a Welding Discharge

The effective development of modern welding technologies and the improvement of equipment and materials inevitably require deep theoretical knowledge about the physical phenomena occurring in the electric arc column and in the near-electrode region. However, there is still no convincing theoretical description of an arc discharge. This article demonstrates, through the generalization of known experimental facts and studies using a high-speed camera, that the conductive channel of an electric arc has a discrete structure, consisting of a set of thin channels through which the main discharge current passes. The cathode spot of an arc discharge is a highly heated and brightly glowing area on the cathode’s surface. Electron emission occurs from this region, which supports the discharge as well as the removal of the cathode material. We propose a new technique to study the reverse side of the cathode spot, revealing a structure consisting of individual cells or fragments of the cathode spot. For the first time, we present the anode spots captured by a high-speed camera. We carry out an analysis of the spots’ structure. We determine the parameters affecting the mobility of cathode and anode spots. We propose a hypothesis based on the obtained experimental facts about the heterogeneous structure of cathode and anode spots in an arc discharge and the existence of current filaments that affect the mobility of spots during arc combustion.

Leaching behavior of sustainable concrete made with coal ash wastes as replacement of cement and sand.

The coal-fired power plant fly ash (FA) and bottom ash (BA) are gradually used as alternative materials in the concrete. However, knowledge of the leaching characteristics of using both incinerator ashes in concrete production is lacking. This work aimed to evaluate the leaching behavior of the FA and BA used in concrete production by employing batch and tank leaching tests. The outcomes of both leaching tests showed that there was no considerable leaching of any trace elements to the environment, and it remains much lower than standard limitations for utilization as construction materials. The results of cumulative mass discharge showed that the slope of flux time for all elements was less than 0.4 and because of that, primary surface wash-off was the main discharge process of all the heavy metals. Strength test results revealed that there was not much difference between coal ash concrete (CAC) and the control mix at the initial age of curing time. Despite that, at a long period of curing time (180 days), the compressive strength of CAC containing 20% FA as cement replacement and 100% BA as fine aggregate replacement increased by 76% due to the pozzolanic reaction of BA and FA in comparison to the normal concrete, while, due to the high porosity of BA, the workability of CAC decreased by 50%. The outcomes of the current work revealed that the combined use of FA and BA can be counted as a promising alternative in the production of sustainable concrete for structural applications toward sustainable development.

D-Electrons of Platinum Alloy Steering CO Pathway for Low-Charge Potential Li-CO2 Batteries.

Aprotic Li-CO2 batteries suffer from sluggish solid-solid co-oxidation kinetics of C and Li2CO3, requiring extremely high charging potentials and leading to serious side reactions and poor energy efficiency. Herein, we introduce a novel approach to address these challenges by modulating the reaction pathway with tailored Pt d-electrons and develop an aprotic Li-CO2 battery with CO and Li2CO3 as the main discharge products. Note that the gas-solid co-oxidation reaction between CO and Li2CO3 is both kinetically and thermodynamically more favorable. Consequently, the Li-CO2 batteries with CoPt alloy-supported on nitrogen-doped carbon nanofiber (CoPt@NCNF) cathode exhibit a charging potential of 2.89 V at 50 μA cm-2, which is the lowest charging potential to date. Moreover, the CoPt@NCNF cathode also shows exceptional cycling stability (218 cycles at 50 μA cm-2) and high energy efficiency up to 74.6 %. Comprehensive experiments and theoretical calculations reveal that the lowered d-band center of CoPt alloy effectively promotes CO desorption and inhibits further CO reduction to C. This work provides promising insights into developing efficient and CO-selective Li-CO2 batteries.

Vector-Time-Resolved In-plume Plasma Current Density Flux Measurement in a Pulsed Plasma Thruster

Plasma plumes are the end products ejected from electric propulsion after complex ionization and acceleration processes. The physics behind the plasma plumes has attracted significant interest due to their interactions with the critical components of satellites and an increased understanding of the relevant processes. Recently, in the front view from a pulsed plasma thruster (PPT), we observed an unclosed vortex structure in the plasma plume, which led us to reconsider the propagation process and the current flux directions inside a plasma plume. To study this plume structure in depth, a highly sensitive Rogowski coil is used here to obtain the current density of the plume over the operating period of a PPT in 3 perpendicular directions. Vector-time-resolved current flux maps were obtained through experimental measurements and the peak current densities were found to reach 50000 mA/cm2 to 250000 mA/cm2. From successive 3-D current flux maps, the complete process of current flow inside a transient plasma plume is observed. The vortex plume structure was found to form during the initial discharge period. The plasma in-plume current is shown to be involved by discharge circuit. After the main discharge is completed, the plasma plume tends to circuit-independent and in self-equilibrium.

A repetitive pulsed electrothermal plasma jet ignition system based on capillary discharge.

Plasma ignition and combustion enhancement is a promising technology in applications of engines, industrial burners, pollutant emissions controls, etc. A new repetitive electrothermal plasma jet ignition system based on ablated capillary discharge under atmospheric pressure is presented in this paper. It consists of a capillary discharge module, a pulse current circuit, a pulse voltage circuit, a current release unit, an LC series resonant circuit, and a control system. The effects of the energy storage capacitor's voltage and resistance in the current release unit on the electrical parameters are investigated. Increasing the capacitor voltage helps to shorten the discharge delay and increase the energy deposition efficiency in the main discharge process. The increase of the resistance in the current release unit leads to a longer discharge delay and higher energy deposition efficiency in the main discharge process. Balanced parameters between the delay of discharge in 66 µs and the energy deposition efficiency in 84% are achieved through optimization, with a peak radiative heat flux of 23MWm-2 and a maximum jet length of 17cm. Repetitive capillary discharge at 20Hz under atmospheric pressure is achieved with the dispersion of energy storage capacitor charging voltage and energy deposition efficiency of 0.3% and 9.6%, respectively. Simplified circuit topology and control logic contribute to the miniaturization of the ignition system.

Hospital Discharge Plan in Family Caregivers of Children with Coronary Artery Aneurysm in Kawasaki Disease: A Review

Objective: The study reviews status, main time nodes and hospital discharge services for family caregivers of children with Kawasaki disease complicated by coronary artery aneurysm to provide references for the development of hospital discharge preparation services for medical personnel and patients. Background: CAL of Kawasaki disease is the main cause of acquired heart disease in children, but there is not enough research on the readiness for hospital discharge. Design: Systematic review of observational and interventional studies.

Severity outcomes of SARS-CoV-2 infection in the Omicron and pre-Omicron periods, in unvaccinated first-time test positive adults less than 65 years old without comorbidity, in Sweden

BackgroundThe COVID-19 pandemic has had several phases with varying characteristics. We aimed to compare severity outcomes in different phases in a population with limited bias from risk factors. MethodsIn a nationwide observational study of all unvaccinated first-time COVID-19 test positive individuals in Sweden aged 18–64 years without comorbidity, from week 45 of 2020 to week 5 of 2022, variant periods with certain variants constituting ≥ 92 % of all whole genome-sequenced cases nationwide, were compared regarding hospitalisation (with main discharge code of COVID-19), severe illness (use of high-flow nasal oxygen or admission to intensive care unit), and death due to COVID-19. Logistic regression was used to estimate odds ratios (ORs) for comparison of these outcomes between variant periods, using adjustments for variant period, age, sex, country of birth, place of residence, income, and education. FindingsThe study included 789,133 individuals, including 15,145 hospitalised individuals. Among all individuals, the adjusted ORs for hospitalisation were 1.7 for the Alpha period vs the Pre-variant period (week 45–52 2020), 1.8 for the Delta period vs the Alpha period, and 0.1 for the Omicron period vs the Delta period (all comparisons significant). Among hospitalised individuals, the adjusted ORs for severe illness were 1.4 for the Alpha period vs the Pre-variant period, 1.7 for the Delta period vs the Alpha period, and 0.5 for the Omicron period vs the Delta period (all comparisons significant), and the adjusted ORs for death were 1.1 for the Alpha period vs the Pre-variant period (non-significant), 1.8 for the Delta period vs the Alpha period (significant), and 0.1 for the Omicron period vs the Delta period (non-significant). InterpretationIn this population with limited bias from risk factors, vaccination, and previous infection, disease severity increased from the pre-variant to the Delta period and then decreased with the Omicron period, among all individuals and among hospitalised individuals. These severity outcome differences should be considered when the pandemic is evaluated.

Numerical investigation of discharge evolution and breakdown characteristics of ArF excimer lasers

The corona bar induced pre–ionization is a crucial preliminary process in the operation of ArF excimer lasers, directly impacting the uniformity and stability of output laser. The ultraviolet corona pre–ionization, as the mainstream method, is tightly coupled with the main discharge process, which complicates analysis. Here, we establish a numerical model of a single pulse discharge incorporating an external circuit to analyze the pre–ionization process and its influence on the breakdown characteristics. (1) By adopting detailed input parameters of photoionization model, we observe uniform and dispersed plasma propagation from the corona bar to the main gap. (2) An artificial boundary condition is proposed to investigate the phenomenological effect of high–energy electrons emission, emphasizing the influence of surface discharge along the cathode. (3) The propagation and breakdown characteristics of the two pre–ionization setup methods, photoionization and background electron density, are compared numerically. This study enhances the understanding of the pre–ionization process in ArF excimer lasers and provides theoretical insights for their optimization and design.

Effect of highway greenbelt constrution on groundwater flow in a semi-arid region.

The highway greenbelt, vigorously promoted in arid and semi-arid areas, has obvious impacts on beautifying the environment, absorbing dust, reducing noise, and maintaining soil and water. Moreover, it affects the characteristics of how water resources are distributed and the regional groundwater cycle. However, the impact of highway greenbelt construction on groundwater flow in semi-arid areas is unknown. The Hubao Highway greenbelt in the north part of the Tumochuan Plain was studied as an example. The paper combines field investigation, remote sensing and mathematical modeling to quantify the impact of highway green space construction on regional groundwater circulation. The results showed that: Trees, shrubs and grasses were the dominant vegetation types in the landscaped area, accounting for 42.17% of the studied area. The total evapotranspiration water consumption of the green belt during the growing season was 471.35 × 104m3. The groundwater recharge in the study area was mainly derived from the lateral recharge in front of the mountain, and the main discharge was the evapotranspiration water consumption of the green belt. This evapotranspiration accounts for 3.31% of the total groundwater recharge. Under the condition that the recharge in front of the mountain remains constant, the evapotranspiration water consumption of the green belt will still have an increasing trend in the future. Appropriate planting of poplar and other high water-consuming trees may be the best way to mitigate the adverse effects of greenbelt evapotranspiration on groundwater resources. The results of this study provide valuable insights for environmental protection and infrastructure development in similar areas.

Understanding trends of US breast cancer hospitalization, mortality and costs using the National Inpatient Sample database.

11162 Background: Studies have shown a rising breast cancer incidence in the US. However, its impact on healthcare utilization is unclear. Our study delves into the previously unexplored territory of hospitalization and cost trends among breast cancer patients, aiming to shed light on resource allocation and potential areas for improvement. Methods: To investigate trends in breast cancer admissions and costs, we queried the National Inpatient Sample database. Patients admitted between January 2011 and December 2019 with following criteria were included in the analysis: female gender, age ≥ 18, and ICD diagnosis code corresponding to unspecified malignant neoplasm of the breast as their primary reason for admission. Our primary outcome was defined as the temporal trends in the number of admissions, discharge rates, length of stay, and cost of hospitalization and mortality rates. Analyses were performed using Stata version 15.1 College station TX: StataCorp LP 2017. Appropriate discharge weights were applied to the dataset during the analyses to account for critical elements of sampling design. A p-value of <0.05 was considered statistically significant. Results: Between 2011 and 2019, hospital admissions for breast cancer as the primary diagnosis declined significantly, from 32,126 to 12,742 (P < 0.001). However, while average length of stay increased slightly from 4.3 to 4.9 days (P < 0.01), hospital charges for breast cancer rose dramatically. Adjusted for inflation, mean charges per patient rose 38.8%, from $50,663.86 in 2011 to $70,334.11 in 2019 (P < 0.001). Despite this surge, the total aggregate cost ("national burden") of hospitalizations with breast cancer as main discharge diagnosis decreased, falling from $1.63 billion in 2011 to $896 million in 2019 (inflation adjusted) (P < 0.001). Discharges for breast cancer peaked in women between 45 and 64, followed by the 65-84 demographic. Compared to the overall decrease in hospitalization rates, the declines in the above age groups were notably steeper with declines of 62% for 45-64 and 48% for 65-84 (p<0.001). Although absolute number of breast cancer deaths decreased from 2011 to 2019, the mortality rate paradoxically increased from 4.3% to 5.8% over the same period (P < 0.001). This seemingly contradictory trend warrants further investigation to better understand contributing factors. Conclusions: While breast cancer diagnoses are on the rise in women, our study reveals a fascinating paradox: significant declines in hospitalization, associated costs, and overall mortality. This encouraging trend likely stems from widespread surveillance mammography with increases in early stage, curable disease diagnosis, and the flourishing landscape of outpatient therapies, including targeted treatments, with more tolerable toxicity profiles allowing for majority of breast cancer care to be completed in the outpatient setting.

Atmospheric pressure uniform dielectric barrier discharge (DBD) in a wide air gap initiated from a narrow starting point

Generating a uniform non-equilibrium plasma in atmospheric pressure air has always been a challenge. It is believed that the maximum spacing for generating a uniform non-equilibrium plasma in atmospheric pressure air, whether using AC or nanosecond pulse drive, is 4 mm. Discharges are always non-uniform when the spacing is greater than 4 mm. In this paper, we propose a new type of dielectric barrier discharge structure to address this challenge. The left end of the structure rapidly increases the discharge spacing from 0.5 mm to 6 mm, while the right side of the main discharge gap maintains a uniform spacing of 6 mm. Nanosecond pulse voltage is used to drive the plasma, an ICCD camera is used to capture the image of the plasma during a discharge pulse cycle, which indicates that a uniform plasma within the 6 mm spacing of the main discharge gap is generated. Upon further reducing the ICCD camera’s exposure time to 20 ns, it is revealed that the uniform plasma is formed due to the rapid propagation of the plasma from left to right at a speed of order of 105 m s−1. Due to the small transverse component of the external electric field, this rapid propagation behavior cannot be due to the external electric field. Therefore, this paper further proposes the hypothesis of electric dipole formation leading to this fast propagation. The hypothesis suggests that the charge separation on the surface of the anode forms an electric dipole, which generates a local discharge at its right end. This local discharge further triggers the discharge in the main gap, and the main gap discharge, in turn, forms a dipole due to charge separation again, by repeating this cycle, the plasma propagates rapidly to the right. Further analysis demonstrates that this dipole can indeed produce a strong electric field of up to 41 kV cm−1 at its right end, which is sufficient to induce a local discharge. Moreover, under such a strong electric field, the electron migration rate can indeed reach 105 m s−1. These findings support the plausibility of this hypothesis.

Elucidating the Role of Electrochemically Formed LiF in Discharge and Aging of Li-CFx Batteries.

Fifty years after its introduction, the lithium-carbon monofluoride (Li-CFx) battery still has the highest cell-level specific energy demonstrated in a practical cell format. However, few studies have analyzed how the main electrochemical discharge product, LiF, evolves during the discharge and cell rest periods. To fill this gap in understanding, we investigated molecular-level and interfacial changes in CFx electrodes upon the discharge and aging of Li-CFx cells, revealing the role of LiF beyond that of a simple discharge product. We reveal that electrochemically formed LiF deposits on the surface of the CFx electrode and subsequently partially disperses into the electrolyte to form a colloidal suspension during cell aging, as determined from galvanostatic electrochemical impedance spectroscopy (EIS), solid-state 19F nuclear magnetic resonance (NMR), dynamic light scattering (DLS), and operando optical light microscopy measurements. Electrochemical LiF formation and LiF dispersion into the electrolyte are distinct competing rate processes that each affect the cell impedance differently. Using knowledge of LiF dispersion and saturation, an in-line EIS method was developed to compute the depth of discharge of CFx cells beyond coulomb counting. Solid-state 19F NMR measurements quantitatively revealed how LiF and CF moieties evolved with discharge. Covalent CF bonds react first, followed by a combination of covalent and ionic CF bonds. Quantitively correlating NMR and electrochemical measurements reveals not only how LiF formation affects cell impedance but also that CF bonds with the most ionic character remain unreacted, which limits realization of the full theoretical specific capacity of the CFx electrode. The results reveal new insights into the electrochemical discharge mechanism of Li-CFx cells and the unique role of LiF in cell discharge and aging, which suggest pretreatment strategies and methods to improve and measure the performance of Li-CFx batteries.

Pulse operation mode of inertial electrostatic plasma confinement devices

The paper discusses the operation features of the inertial electrostatic plasma confinement (IEC) devices in the pulsed high voltage mode. The pulse operation mode offers significant advantages in IEC devices, which are associated with high discharge currents that are inaccessible for continuous operating modes. However, the implementation of such operating modes is associated with a number of physical limitations and technical difficulties.A stand with an IEC chamber powered by a high-voltage pulse transformer and a unit for gas preliminary ionization in the IEC chamber has been developed. In the chamber, ions are accelerated from a background glow discharge. A study of the burning background discharge in the IEC chamber, background discharge current Ipre influence on the duration of current and voltage pulses of the main discharge and the delay between them was carried out. The results of the neutron yield measuring in an IEC chamber operating in pulsed mode are presented at a charging voltage up to 105 kV, a discharge current amplitude of several tens of amperes, a preionization current of 8 mA, and a pulse repetition rate from single to 300 Hz. A stable neutron flux with an energy of 2.5 MeV at a level of 106 neutrons/s was experimentally obtained.

Spatio-temporal distribution of renewable freshwater resources and their availability in Kosovo—an analysis from the Eastern Region

The study aims to analyze the availability of renewable freshwater resources and their spatiotemporal distribution in the Eastern Region of Kosovo (ERK). As a crucible resource for agricultural, industrial, and commercial activities, water scarcity will lead to water shortages. Kosovo is a landlocked country, and ERK is the most important region for industrial activities (coal, mines) and agricultural use (plains). Located in continental climate conditions, surrounded by middle to high-altitude mountains, the region does not have a favorable spatio-temporal distribution of freshwaters. The determination of the water resources is based on the amount of surface runoff, which being divided per capita, gives indications of the water resources of a region (catchment). For our aims, main river discharge and population statistics are used to analyze the spatiotemporal distribution and availability of renewable freshwater in ERK. Falkenmark Freshwater Indicator with 1.483 m³/capita/year shows that ERK lies under water scarcity, and existing water reservoirs offer low security for water withdrawals, and further reservoirs would prevent water scarcity in the region.

Novel method for identifying the stages of discharge underwater based on impedance change characteristic

It is difficult to determine the discharge stages in a fixed time of repetitive discharge underwater due to the arc formation process being susceptible to external environmental influences. This paper proposes a novel underwater discharge stage identification method based on the Strong Tracking Filter (STF) and impedance change characteristics. The time-varying equivalent circuit model of the discharge underwater is established based on the plasma theory analysis of the impedance change characteristics and mechanism of the discharge process. The STF is used to reduce the randomness of the impedance of repeated discharges underwater, and then the universal identification resistance data is obtained. Based on the resistance variation characteristics of the discriminating resistance of the pre-breakdown, main, and oscillatory discharge stages, the threshold values for determining the discharge stage are obtained. These include the threshold values for the resistance variation rate (K) and the moment (t). Experimental and error analysis results demonstrate the efficacy of this innovative method in discharge stage determination, with a maximum mean square deviation of S cr less than 1.761.

Impact on urban river water quality and pollution control of water environmental management projects based on SMS-Mike21 coupled simulation

To explore the impact of expanding Nanyang Sewage Purification Center (NSPC) on the main sewage discharge area of Bai River, we constructed a 2D hydrodynamic-water quality model based on surface water modeling system (SMS) and Mike21. Simulating three sewage discharge conditions in wet, normal, and dry season, we evaluated three indicators (COD, NH3-N, and BOD5) by the single-factor pollution index and provided recommendations for water environment management. The results showed that, maximum absolute error of water level was 0.08 m, percentage bias coefficient of COD, NH3-N and BOD5 were 19.3%, 16.2% and 23.1%, indicating the SMS and Mike21 coupling model was applicable; water quality of the assessment section were upgraded from the original class IV, V, V (Condition 1) to class IV, III, II (Condition 2) and class IV, III, III (Condition 3) in the wet, normal and dry season, indicating that NSPC's expansion had improved the water quality of the assessment section; as the primary pollutant, BOD5 concentration in the downstream was lower than the upstream, which was due to the dilution effect of river. Therefore, on the basis of expanding NSPC, we recommend to remediation of BOD5 by physical, chemical, and biological methods. This study broadens new ideas for the application of Mike21, and provide a reference for the prevention and improvement of river water pollution in urban areas.

Study of irrigation aspect in the interconnection system of Telaga Tanjung and Singin Ponds in Tabanan Regency

Interconnection is a channel that links multiple water channel systems with those downstream of a river area. The proposed system will utilize existing canals in Gadungan, Matan, and Unun Irrigation Areas, extending to the Lambuk Reservoir dam system. The problem is that irrigation areas downstream of the Lambuk Reservoir are Lambuk (726 ha), Babakan Anyar (42 ha), and Lanyah (281 ha) experience water shortages (planting intensity of 170% to 200%) during the dry season. The study utilized water balance methods in rice fields, the basic year method for main discharge at weirs, and interconnection channel analysis for water needs calculation. From the water balance analysis, the Singin System cannot make a new interconnection channel to the Lambuk Reservoir because the available water in each reservoir can only irrigate the Matan and Unun Irrigation Areas. From the Telaga Tunjung System, there is still a lot of water available, especially during the rainy season, so that it can supply the reservoir for the Lambuk Reservoir. This means that the interconnection system from this reservoir still needs to be created from the primary channel of the Gadungan Irrigation Area.

Formation of Extended Tubular Plasma in Argon at Low Pressure and in a Weak Longitudinal Magnetic Field

The results of experimental studies on the formation and subsequent evolution of extended (l = 300 mm) and thin-walled (Δr ≈ 10 mm) tubular (2r ≈ 110 mm) plasma in a weak longitudinal magnetic field (B = 175 G) without the use of a thermionic cathode are presented. The cylindrical chamber in which the tubular plasma was formed was pumped with high purity argon (99.998%) at an average velocity of about 1 m/s at a pressure of P = 10–3–10–2 Torr. Two methods of creating seed electrons initiating the development of ionization avalanches were used. The difference inherent to these methods has been established in the dynamics of breakdown, completing in the formation of a tubular discharge. In the first of them, a pulsed discharge preceding the high voltage supply of the main discharge created gas preionization in a small area around the sectioned cathodes. In the second method, seed electrons were created in the entire working area of the discharge chamber by an RF discharge with a frequency of 85 kHz and duration of about 1 s. High-speed shooting with a 4-frame ICCD camera allowed us to establish the dynamics of tubular discharge formation at all its stages. Measurements of the longitudinal and radial discharge current were carried out. The results we obtained showed the possibility of spatial isolation of an extended tubular plasma from the close located metal wall of the discharge chamber by using a weak longitudinal magnetic field.

A Biopsychosocial Approach to Persistent Post-COVID-19 Fatigue and Cognitive Complaints: Results of the Prospective Multicenter NeNeSCo Study

ObjectiveTo evaluate whether psychological and social factors complement biomedical factors in understanding post-COVID-19 fatigue and cognitive complaints. Additionally, to incorporate objective (neuro-cognitive) and subjective (patient-reported) variables in identifying factors related to post-COVID-19 fatigue and cognitive complaints. DesignProspective, multicenter cohort study. SettingSix Dutch hospitals. Participants205 initially hospitalized (March-June 2020), confirmed patients with SARS-CoV-2, aged ≥18 years, physically able to visit the hospital, without prior cognitive deficit, magnetic resonance imaging (MRI) contraindication, or severe neurologic damage post-hospital discharge (N=205). InterventionsNot applicable. Main Outcome MeasuresNine months post-hospital discharge, a 3T MRI scan and cognitive testing were performed and patients completed questionnaires. Medical data were retrieved from medical dossiers. Hierarchical regression analyses were performed on fatigue severity (Fatigue Severity Scale; FSS) and cognitive complaints (Cognitive Consequences after Intensive Care Admission; CLC-IC; dichotomized into CLC-high/low). Variable blocks: (1) Demographic and premorbid factors (sex, age, education, comorbidities), (2) Illness severity (ICU/general ward, PROMIS physical functioning [PROMIS-PF]), (3) Neuro-cognitive factors (self-reported neurological symptoms, MRI abnormalities, cognitive performance), (4) Psychological and social factors (Hospital Anxiety and Depression Scale [HADS], Utrecht Coping List, Social Support List), and (5) Fatigue or cognitive complaints. ResultsThe final models explained 60% (FSS) and 48% (CLC-IC) variance, with most blocks (except neuro-cognitive factors for FSS) significantly contributing. Psychological and social factors accounted for 5% (FSS) and 11% (CLC-IC) unique variance. Higher FSS scores were associated with younger age (P=.01), lower PROMIS-PF (P<.001), higher HADS-Depression (P=.03), and CLC-high (P=.04). Greater odds of CLC-high were observed in individuals perceiving more social support (OR=1.07, P<.05). ConclusionsResults show that psychological and social factors add to biomedical factors in explaining persistent post-COVID-19 fatigue and cognitive complaints. Objective neuro-cognitive factors were not associated with symptoms. Findings highlight the importance of multidomain treatment, including psychosocial care, which may not target biologically-rooted symptoms directly but may reduce associated distress.