Low Discharge Research Articles

Fine-Tuning Cathode Performance: The Influence of Argon Deposition Pressure on LiMn2O4 Thin Film Electrochemistry for Li-Ion Batteries

Lithium manganese oxide (LiMn2O4) is an effective cathode material for high-capacity lithium-ion (Li-ion) batteries. Therefore, to optimize battery efficiency, it is essential to understand how sputtering deposition conditions affect the quality and performance of LiMn2O4. This research examines how argon deposition pressure affects the stoichiometric characteristics and electrochemical performance of LiMn2O4. The study finds that changing argon deposition pressures, from a low of 5 mTorr to a high of 30 mTorr, results in the formation of different coating stoichiometries. At low argon deposition pressures, stoichiometric LiMn2O4 cathode coatings formed, exhibiting the highest discharge capacity of 115 mAh/g. Conversely, at high argon deposition pressures, non-stoichiometric LiMn2O4 with lithium deficiency was produced. These coatings exhibited diminished electrochemical behavior, achieving a discharge capacity of only 70 mAh/g at 5 mTorr. The lack of lithium resulted in a significant reduction in electrochemical performance, indicated by a high surface charge transfer resistance (R2 = 48,529 Ω), which led to a low discharge capacity of 40 mAh/g.

Collaborative Hollow Porous Structure Design and N Doping to Achieve a Win–Win Situation of “Stable” and “Fast” Lithium Battery

ABSTRACTPolymer‐derived SiOC materials are widely regarded as a new generation of anodes owing to their high specific capacity, low discharge platform, tunable chemical/structural composition, and good structural stability. However, tailoring the structure of SiOC to improve its electrochemical performance while simultaneously achieving elemental doping remains a challenge. Besides, the lithium storage mechanism and the structural evolution process of SiOC are still not fully understood due to its complex structure. In this study, a hollow porous SiOCN (Hp‐SiOCN) featuring abundant oxygen defects is successfully prepared, achieving both the creation of a hollow porous structure and nitrogen element doping in one step, finally enhancing the structural stability and improving the lithium storage kinetics of Hp‐SiOCN. In addition, the formation of a fully reversible structural unit, SiO3C─N, through the chemical interaction between N and Si/C, showcases a strong lithium adsorption capacity. Taking advantage of these combined benefits, the as‐prepared Hp‐SiOCN electrode delivers a reversible specific capacity of 412 mAh g−1 (93% capacity retention) after 500 cycles at 1.0 A g−1 and exhibited only 4% electrode expansion. This work offers valuable mechanistic insights into the synergistic optimization of elemental doping and structural design in SiOC, paving the way for advanced developments in battery technology.

Influence of regulated water discharges on phytoplankton composition and biomass in a subtropical canal

Phytoplankton composition and biomass were investigated in the C-43 Canal in southwest Florida during a period of shifting discharges from water control structures. The canal receives regulated discharges from eutrophic Lake Okeechobee via the S77 structure. During periods of high S77 discharge in spring and early summer, cyanobacteria biomass dominated the phytoplankton community, including blooms of the harmful algal bloom (HAB) species Raphidiopsis raciborskii, Limnothrix redekei and Microcystis aeruginosa. During periods of low discharges from the lake, in mid-summer and autumn, water inputs to the canal came primarily from tributaries in the watershed surrounding the C-43. Phytoplankton biomass decreased, but the relative importance of dinoflagellates increased, including a bloom in July. The dinoflagellate community included Ceratium, Durinskia baltica, Glochidinium penardiforme, Gymnodinium fuscum, Parvodinium goslaviense, Parvodinium umbonatum/inconspicuum complex, Peridiniopsis quadridens, Woloszynskia reticulata, and an unidentified thecate and athecate species. D. baltica and P. goslaviense were recorded for the first time in Florida. Data was also obtained on water temperature, conductivity, fluorescent dissolved organic matter, chlorophyll a, total nitrogen, dissolved inorganic nitrogen, total phosphorus, PO4, discharge rates from water control structures, and water residence times. Results show that temporal shifts in the sources and rates of water inputs to the C-43 influence the character of environmental conditions that define phytoplankton composition and biomass in the canal. This suggests that management of discharges can play a role in mitigating HABs in the canal and downstream coastal environments receiving water from the canal.

Modeling saline-fluid flow through subglacial channels

Abstract. Subglacial hydrological systems impact ice dynamics, biological environments, and sediment transport. Previous numerical models of channelized subglacial flow have focused on freshwater in temperate ice without considering variable fluid chemistry and properties. Saline fluids can exist in cold glacier systems where freshwater cannot, making the routing of these fluids critical for understanding their influence on geochemical and physical processes in relevant glacial environments. This study advances previous efforts by modeling saline fluid in cold glacier systems, where variable fluid chemistry significantly influences melt rates and drainage processes. We model the drainage of a hypersaline subglacial lake through an ice-walled channel, highlighting the impact of salinity on channel evolution. The model results show that, in subglacial systems at salinity-dependent melting points, channel walls grow more slowly when fluids have higher salt concentrations, leading to significantly lower discharge rates. At higher salinities, more energy is required to warm the fluid to the new melting point as the brine is diluted, which reduces the energy available for melting the channel walls. We also highlight the impact of increased fluid density on subglacial drainage and the importance of accounting for accurate suspended sediment concentrations when modeling outburst floods. This model provides a framework to assess the impact of fluid chemistry and properties on the spatial and temporal variations of fluid flux.

Lattice Boltzmann simulation of direct-current glow discharge at low pressure

To analyze electro-hydrodynamic behavior of low pressure direct-current glow discharge plasma, we propose a numerical model based on the lattice Boltzmann method and the drift-diffusion theory of gas discharge. In our model, three plasma species (excited species, electrons and ions) are considered with eight elementary chemical reactions among them and standard lattice Boltzmann method, finite difference-lattice Boltzmann method and finite difference method are employed for electrons, heavy species (ions and excited species) and electric potential, respectively. The proposed model introduces a unique coupling scheme between electrons and heavy species using a consistent time step and grid, enhancing accuracy and stability of numerical simulations. Our model is applied to one- and two-dimensional analyses of glow discharge, and the results are in good agreement with those from previous works.

Influence of River Discharge and Tides on the Salinity Structure at the Magdalena River Estuary

The salinity structure in the Magdalena River estuary results from a massive river discharge and a micro-tidal regime over a narrow-deep channel. Both environmental forcings are analyzed here to assess their effects on the temporal and spatial variability of the estuarine system. We investigated long-term (seasonal to interannual) and short-term (diurnal) changes in salinity structure and circulation through in situ measurements and a 3D hydrodynamic model ensemble (21 model runs). The measurements cover low (below 10th percentile) and mean river discharge conditions. Results show that the Magdalena River estuary (MRE) behaves as a strongly stratified system during the dry season (February to April) and as a vertically homogeneous one during the wet and transitional seasons when the river plume exhibits a lift-off regime at the mouth. A river discharge threshold has been found for the estuary to lift-off regime transition, corresponding to the 30th percentile (5200 m3/s). At the seasonal scale, the salinity intrusion length in the MRE shows more reactivity to river discharge variability than other reported strongly stratified estuaries; it is reflected in the scaling factor n\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$n$$\\end{document} in the relationship L∼Q-n\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$L\\sim {Q}^{-n}$$\\end{document}. A n\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$n$$\\end{document} value of 3.9 is the best fit for the MRE; nevertheless, it follows the Schijf and Schönfeld theoretical model solution for a prismatic flat configuration. Micro tides modulate the salinity intrusion on the diurnal cycle with a more significant effect on salinity intrusion and water exchange than previously reported, particularly during low discharge conditions. The findings from measurements and model scenarios for the MRE can be broadly applied and stand for an exemplary tropical, micro-tidal, anthropogenic intervened system.

(Invited) The Potential of Pulsed Low Temperature Plasmas for the Controlled Deposition of Plasma Polymer Ultrathin Films and Composite Nanomaterials (Invited)

Low temperature discharges with their unique non-equilibrium properties are often used in industrial processes for the deposition of ultra-thin (plasma) polymer films. Applications for this type of thin films range from protective coatings to their use in membranes, biosensors and batteries. However, the properties of these thin films are highly dependent on the choice of discharge parameters, both in terms of their surface topography and their chemical composition. This paper deals with the great potential of pulsed discharges for the controlled deposition of plasma polymer films. The influence of pulse frequency and duty cycle on the deposition process and the properties of the resulting thin films is discussed from a theoretical point of view and is illustrated by experimental results. The latter concern examples of experiments carried out with discharges operated with acetylene or aniline, as well as functional coatings on top of MoS2, 2D graphene or CNTs. The work was supported by the project PEGASUS (Plasma Enabled and Graphene Allowed Synthesis of Unique nano-structures), funded by the European Union’s Horizon research innovation program under Grant Agreement No. 766894; EU Graphene Flagship FLAG-ERA III JTC 2021 project VEGA (No. PR-11938) Project-ANR-21-GRF1-0004. Further support was obtained via ARD MATEX Centre-Val de Loire Region (projects Carbon2 and Carbon3) and project Orleans Metropole (both France).

Trade-off between surface area and tap density when selecting carbon adsorbents for hydrogen compression

While high-surface-area activated carbons (ACs) are widely recognized as essential for maximizing H2 adsorption, this study emphasizes the importance of tap density and explores the potential of using more cost-effective ACs with lower surface areas for H2 compression by adsorption. We thus critically evaluated the performance of an adsorption compressor using six commercial ACs with BET areas ranging from 1000 to 3300 m2/g and tap densities from 270 to 560 kg m−3. Experimental and numerical analyses revealed the impact of these parameters on compression efficiency. Our results suggest that optimizing both surface area and tap density is essential for improving the viability of porous materials in the hydrogen economy. Specifically, the ACs tested here can achieve outlet pressures up to 70 MPa, but with minimal H2 discharge. Therefore, lower discharge pressures (<30 MPa) are required to maintain a stable H2 flow rate, which can be further improved at temperatures above ambient (298 K).

High‐Potential and Stable Organic Cathode for Rechargeable Batteries with Fast‐Charging and Wide‐Temperature Adaptability

AbstractOrganic carbonyl compounds have been recognized as promising electrodes due to multiple active sites, abundant element resources and flexible structural designability, while their practical applications are still hindered by the easy solubility and low discharge potential. Herein, a novel bipolar polymer composite (TAC) was well‐designed by grafting p‐type triphenylamine units onto n‐type anthraquinone to form an extended π‐conjugated structure and in situ growing on carbon nanotubes, which was proved not only with higher discharge potential but also effectively suppress the dissolution issues. Moreover, TAC combined the advantages of different active sites and behaved a dual‐ion storage mechanism. Benefitting from the in situ polymerization process, TAC with tube‐type core–shell structure exhibited enhanced electron transport and improved utilization of active sites, resulting in high capacity (193 mAh g−1), outstanding rate performance (fast charging within 17 s), long‐term stability (a high capacity retention of 87 % after 1000 cycles) and high mass loading (10 mg cm−2). Additionally, TAC can well adapt to the temperature change, outputting a capacity of 72 mAh g−1 at −60 °C and 165 mAh g−1 at 80 °C. Such versatile polymer structure inspires the design of high performance organic materials for rechargeable batteries to satisfy high stability and wide temperature operations.

Elucidating the nature of secondary phases in LiNi0.5Mn1.5O4 cathode materials using correlative Raman-SEM microscopy

LiNi0.5Mn1.5O4 (LNMO) is a promising next-generation cathode material for lithium-ion batteries (LIBs) due to its high-energy and high-power density. However, its commercial adoption is hindered by the unstable LNMO/electrolyte interface due to high operating voltages and structural degradation arising from Jahn-Teller distortion and metal-ion dissolution resulting in poor cycling stability. Additionally, the high-temperature calcination beyond 700 °C often results in secondary phases such as rock salt NiO, Li1-xNixO, Ni6MnO8 or Li2MnO3, whose precise chemical compositions and their influence on electrochemical performance remain unclear. Traditional analytical techniques such as X-ray diffraction (XRD) or neutron diffraction face challenges in resolving these secondary phases due to low phase fractions and overlapping reflections with the LNMO phase. Here, we address these challenges using correlative Raman-Scanning electron microscopy (Raman-SEM) to characterize secondary phases in LNMO materials that were synthesized under various synthesis conditions and evaluated their impact on the electrochemical performance. Our results reveal the synthesis-dependent emergence of three distinct secondary phases in LNMO materials synthesized at 1000 °C, a phenomenon that, to our knowledge, has not been previously reported. Specifically, LNMO synthesized at 900 °C shows the coexistence of Ni6MnO8 and Li2MnO3 phases, while synthesized at 1000 °C also exhibits a Mn3O4 phase. Furthermore, an increased amount of these secondary phases in LNMO led to a lower discharge capacity due to their electrochemical inactive nature. However, these phases do not negatively impact the rate capability or the long-term cycling performance of the LNMO materials. These insights are crucial for advancing the development of LNMO cathode materials for next-generation LIBs.

Solvent Polarity‐Induced Regulation of Cation Solvation Sheaths for High‐Voltage Zinc‐Based Batteries with a 1.94 V Discharge Platform

AbstractTo address the challenge of low discharge platforms (&lt;1.5 V) in aqueous zinc‐based batteries, highly concentrated salts have been explored due to their wide electrochemical window (~3 V). However, these electrolytes mainly prevent hydrogen evolution and dendrite growth at the anode without significantly enhancing voltage performance. Herein we introduce an approach by adjusting solvent polarity to regulate cation solvation sheaths in hybrid electrolytes, reducing Zn/Zn2+ oxidation potential and water activity. Through strong cation‐water coordination and hydrogen bonding between dimethylsulfoxide and water, the designed electrolyte, at a low concentration, achieves a broader electrochemical window (4 V) than conventional concentrated electrolytes. Using this electrolyte, a Zn/Zn battery showed an impressive cycle life of 4340 cycles, while a Zn/lithium manganate battery delivered a high discharge platform of over 1.9 V with exceptional cycling stability. A Zn‐based micro‐battery with a polyvinyl alcohol‐based hybrid electrolyte also achieved a record‐high discharge platform of 1.94 V. This work presents a promising strategy for developing low‐concentration electrolytes for high‐performance sustainable energy storage.

Solvent Polarity-Induced Regulation of Cation Solvation Sheaths for High-Voltage Zinc-Based Batteries with a 1.94 V Discharge Platform.

To address the challenge of low discharge platforms (<1.5 V) in aqueous zinc-based batteries, highly concentrated salts have been explored due to their wide electrochemical window (~3 V). However, these electrolytes mainly prevent hydrogen evolution and dendrite growth at the anode without significantly enhancing voltage performance. Herein we introduce an approach by adjusting solvent polarity to regulate cation solvation sheaths in hybrid electrolytes, reducing Zn/Zn2+ oxidation potential and water activity. Through strong cation-water coordination and hydrogen bonding between dimethylsulfoxide and water, the designed electrolyte, at a low concentration, achieves a broader electrochemical window (4 V) than conventional concentrated electrolytes. Using this electrolyte, a Zn/Zn battery showed an impressive cycle life of 4340 cycles, while a Zn/lithium manganate battery delivered a high discharge platform of over 1.9 V with exceptional cycling stability. A Zn-based micro-battery with a polyvinyl alcohol-based hybrid electrolyte also achieved a record-high discharge platform of 1.94 V. This work presents a promising strategy for developing low-concentration electrolytes for high-performance sustainable energy storage.

Pre-existing dementia is associated with 2-3 folds risk for in-hospital mortality and complications after intracerebral hemorrhage stroke.

Pre-existing dementia was related to poor functional outcome after intracerebral hemorrhage (ICH), and its commonly underlying pathologies were considered as cerebral amyloid angiopathy. But the impact of pre-existing dementia on in-hospital mortality in Chinese ICH patients has not been well characterized. To investigate the association between pre-existing dementia and in-hospital mortality after ICH. Data were extracted from the China Stroke Center Alliance database. Information about the existence of prior to stroke dementia was obtained from next of kin informants and registered in clinical charts. Patients' characteristics, in-hospital mortality, home discharge and complications were compared between ICH patients with and without pre-existing dementia. Out of the 72,318 ICH patients, we identified 328 patients with pre-existing dementia. Patients with pre-existing dementia were more likely to experience greater stroke severity as measured by the National Institute of Health Stroke Scale and Glasgow Coma Scale. In the adjusted models, the presence of pre-existing dementia was associated with an increased risk of in-hospital mortality (OR 2.31, 95% CI 1.12-4.77), more frequent in-hospital complications of pulmonary embolism (OR 5.41, 95% CI 1.16-25.14), pneumonia (OR 1.58, 95% CI 1.08-2.33), urinary tract infection (OR 2.37, 95% CI 1.21-4.64), gastrointestinal bleeding (OR 2.39, 95% CI 1.27-4.49) and lower home discharge (OR 0.59, 95% CI 0.38∼0.93). ICH patients with pre-existing dementia are more likely to suffer from greater stroke severity, poorer outcomes and lower home discharge. Future studies should evaluate the value of intensive risk factor control among individuals with pre-existing dementia for stroke prevention.

Development of pilot-scale plasma bubble reactors for efficient antibiotics removal in wastewater

Plasma bubble (PB) is a promising technology to control antibiotic wastewater pollution. However, the practical implementation of PB technology at the industrial-scale is still underdeveloped. In addition, the influence of different discharge modes for PB on wastewater treatment is largely unknown. This study designed pilot-scale PB reactors with different discharge modes to investigate the degradation effect of norfloxacin (NOR) and tetracycline (TC) in bulk tap water. Results indicate that the dielectric barrier discharge (DBD) mode with low average discharge power demonstrates superior degradation ability and higher production of O3(g) and .O2−(aq) compared to the spark mode which exhibits the high-intensity spark discharge in the tip area of the tube. After 40 min of treatment in a Double DBD reactor, 97.4% and 100% of NOR and TC are removed from 2 L tap water, attributed to the accumulation of antibiotic molecules by PBs and the in-situ generation of O3(g) and .O2−(aq) produced by plasma. Furthermore, a larger-scale PB reactor is developed by creating an array of four DBD reactors, effectively degrading 8 L mixed antibiotics solution. This study provides valuable insights for PB reactor design and the degradation performance of antibiotic wastewater, which will contribute to the further development of synergistic systems for plasma degradation.

Effective Stabilization of Organic Cathodes Through Formation of a Protective Solid Electrolyte Interface Layer via Reduction.

2,5-Dihydroxy-1,4-benzoquinone (DHBQ) is a promising cathode material, but its high solubility in electrolytes leads to rapid capacity degradation. This study investigates the dilithium salt of DHBQ, Li2DHBQ, as a cathode material for lithium-ion batteries (LIBs). Despite minimal solubility, Li2DHBQ cathodes suffer rapid capacity decay due to severe morphological damage within the voltage range of 1.5-3.0 V. To stabilize morphology, we promoted a protective solid electrolyte interphase (SEI) layer on Li2DHBQ particles by lowering the discharge cutoff voltage. Cycling the battery with a 0.5 V discharge cutoff voltage achieved an optimal SEI layer, significantly improving Li2DHBQ's morphological stability. Consequently, the battery maintained 170 mAh g-1 with a low decay rate of 0.16% within a voltage range of 0.5-3.0 V after 200 cycles at 500 mA g-1. Furthermore, initial cycling at a 0.5 V discharge cutoff for 20 cycles to form an SEI layer, followed by cycling at a normal 1.5 V discharge cutoff, retained a higher capacity of 187 mAh g⁻¹ after 200 cycles. This study demonstrates the effectiveness of forming a cathode SEI layer at low discharge voltages as a new approach to stabilizing organic cathode materials.

Impacts of river flow and thermal regimes on fish growth dynamics during early life history

Growth during early life stages is critical to fish population persistence. Few studies explore how river discharge and thermal regimes impact growth dynamics of young-of-the-year (YOY) fishes. We used otolith biochronologies and generalised additive mixed models to partition the effects of age, individual, river, temperature, discharge, and variance in discharge on daily growth rates of YOY fishes with an opportunistic life-history strategy: Galaxias vulgaris and Gobiomorphus breviceps. Growth of both species increased with temperature. Galaxias growth decreased with discharge, while Gobiomorphus growth increased with lowered discharge but only to a point (ca. 1/3 of median discharge), after which growth plateaued. Floods had a strong negative effect on YOY growth. Our study systems and species had different characteristics to those that formed the basis of the Riverscape Recruitment Synthesis Model (RRSM) and may explain why our results were only partially consistent with flow predictions for opportunistic species of the RRSM. Further, Galaxias growth was a negative function of high-frequency, daily variation in flow, and we present testable hypotheses to explain this result.

Hepatitis B Virus-Related Cirrhosis and Hepatocellular Carcinoma Hospital Discharge Rates from 2005 to 2021 in Spain: Impact of Universal Vaccination.

Background: The main consequences of chronic hepatitis B virus (HBV) infections are cirrhosis and hepatocellular carcinoma (HCC), both associated with frequent hospitalization. The aim of this study was to analyze the impact of universal HBV vaccination in Spain on chronic HBV-related hospital discharges from 2005 to 2021. Methods: Using data from the Minimum Basic Data Set of the Spanish National Health System, we calculated the hospital discharge rate ratio (HDRR) and 95% confidence interval (CI) values for chronic HBV-related discharges between 2005 and 2021. For comparative purposes, we calculated the HDRR and 95% confidence interval (CI) values for the early (2005-2013) and later (2014-2021) periods and the vaccinated compared with unvaccinated cohorts for the 20-39 age group. Results: The hospital discharge rate per 1,000,000 people was 3.08 in 2005 and 4.50 in 2021 for HCC, and 4.81 in 2005 and 1.92 in 2021 for cirrhosis. Comparing the early and later periods, values were higher for HCC (HDRR 1.13; 95% CI: 1.06-1.20) and lower for cirrhosis (HDRR 0.56; 95% CI: 0.51-0.60). The rate for the 20-39 age group was lower for the vaccinated compared with the unvaccinated cohorts overall (HDRR 0.53; 95% CI: 0.45-0.62), for HCC (HDRR 0.66; 95% CI: 0.53-0.82), and for cirrhosis (HDRR 0.41; 95% CI: 0.33-0.53). Conclusions: This study describes the important impact, after 25 years, of universal HBV vaccination in Spain: cirrhosis hospital discharge rate was reduced, and the vaccinated cohorts, compared with the unvaccinated cohorts in the 20-39 age group, had a lower hospital discharge rate of both HCC and cirrhosis.

High-Potential and Stable Organic Cathode for Rechargeable Batteries with Fast-Charging and Wide-Temperature Adaptability.

Organic carbonyl compounds have been recognized as promising electrodes due to multiple active sites, abundant element resources and flexible structural designability, while their practical applications are still hindered by the easy solubility and low discharge potential. Herein, a novel bipolar polymer composite (TAC) was well-designed by grafting p-type triphenylamine units onto n-type anthraquinone to form an extended π-conjugated structure and in situ growing on carbon nanotubes, which was proved not only with higher discharge potential but also effectively suppress the dissolution issues. Moreover, TAC combined the advantages of different active sites and behaved a dual-ion storage mechanism. Benefitting from the in situ polymerization process, TAC with tube-type core-shell structure exhibited enhanced electron transport and improved utilization of active sites, resulting in high capacity (193 mAh g-1), outstanding rate performance (fast charging within 17 s), long-term stability (a high capacity retention of 87 % after 1000 cycles) and high mass loading (10 mg cm-2). Additionally, TAC can well adapt to the temperature change, outputting a capacity of 72 mAh g-1 at -60 °C and 165 mAh g-1 at 80 °C. Such versatile polymer structure inspires the design of high performance organic materials for rechargeable batteries to satisfy high stability and wide temperature operations.

Low current iodine-fed hollow cathode discharge: insights from fluid model

Abstract As one of the fundamental components, hollow cathodes using noble gas propellant are widely used in electric thrusters. Iodine has become one of the ideal alternative propellants due to its economy and good chemical properties, while due to the complex reactions, characteristics and proper functioning of iodine-fed hollow cathodes are still unknown. Therefore, a model is needed to understand the physical-chemical process of the iodine-fed hollow cathode discharge. In this work, a self-consistent two-dimensional fluid model of the low-current iodine-fed hollow cathode discharge with detailed non-equilibrium plasma chemistry is developed and verified by the voltages of the keeper and anode obtained in the experiments. Simulations show that the electron impact ionization with iodine atoms dominates the discharge process as the density of iodine atoms is much higher than that of iodine molecules due to the electron impact dissociation and thermal dissociation. Moreover, the power balance analysis shows the heating of electrons contributed by the electric field mainly takes place near the keeper and the orifice. Ion current heating contributes significantly to the gas heating compared with the heating by the electron elastic collisions with I and I2 and the heat release or consumption during the neutral reactions. Furthermore, the influence of electronegativity on plasma characteristics is analysed. Simulations involving I− ions bring higher values of ionization degree, discharge power as well as maximum electron and gas temperatures compared with those without I−. This is similar to the differences in the plasma properties between the iodine-fed and xenon-fed hollow cathode to which the low ionization energy, large collision ionization cross-section and the electronegativity of iodine contribute together. In all, these findings can better predict the plasma behaviours in the iodine-fed hollow cathode discharge and may promote the development of the electric propulsion system using iodine propellant.

Open versus minimally invasive hepatic and pancreatic surgery: 1-year costs, healthcare utilization and days of work lost

IntroductionUtilization of minimally invasive surgery (MIS) has become increasingly popular due to its potential benefits such as earlier recovery and reduced morbidity. We sought to characterize differences in 1-year healthcare costs and missed workdays among patients undergoing MIS and open surgery for a hepatic or pancreatic indication. MethodsData on patients who underwent hepatic and pancreatic resection were obtained from the IBM Marketscan database. Generalized linear models were utilized to compare healthcare costs and missed workdays among patients undergoing MIS versus open surgery. ResultsAmong 8705 patients, 85.0 % (n = 7399) and 15.0 % (n = 1306) patients underwent an open or MIS HP procedure, respectively. In the unmatched cohort, patients who underwent MIS were more likely to be female (62.7 % vs. 54.6 %) and were less likely to have a Charlson Comorbidity Index score >2 (34.5 % vs. 49.6 %) (both p < 0.05). After entropy balancing, multivariable analysis revealed that MIS was associated with lower 1-year post discharge expenditures (mean difference -$9,739, 95%CI-$12,893, -$6585) and fewer missed workdays at 1-year post-discharge (IRR 0.84, 95%CI 0.81–0.87) (all p < 0.001). DiscussionAt index hospitalization and 1-year post-discharge, an HP MIS approach was associated with lower healthcare expenditures versus open surgery for hepatic and pancreatic resection, as well as fewer missed workdays.