Intensive Discharge Research Articles

Пространственно-временная изменчивость грозовой активности на территории Северного Кавказа

The analysis of the long-term observations (2008–2019) of thunderstorm activity in the North Caucasus using the High-mountain Geophysical Institute lightning detection network with LS8000 and LS7002 sensors is performed. Climatic and orographic regional factors forming the spatial heterogeneity of thunderstorm activity in the analyzed region are identified. It is shown that the number of thunderstorm events, their direction and lightning discharge intensity determine microphysical processes in the atmosphere, namely, the intensity of cloud and precipitation formation. Keywords: thunderstorm activity, climate, lightning, lightning detection network, precipitation, radar High-

Growth characteristics and properties of plasma electrolytic oxidation coatings produced in different electrolytes on SiCp/Al composite

PEO coatings on SiCp/Al composites generated in phosphate, silicate, and aluminate electrolytes are compared to reveal the effect of the electrolyte composition on the coating formation process and coating performance. The observed significant disparity in spark discharge highlights the considerable influence of the electrolyte composition on the coating growth of the SiCp/Al composite surface. Within the plasma discharge zone, the local temperature ranges are approximately 6000 K–12000 K for silicate electrolyte, 6000 K–10000 K for aluminate electrolyte, and 4000 K–5000 K for phosphate electrolyte. Regarding spark discharge intensity, silicate electrolyte exhibits the highest discharge, followed by aluminate electrolyte, while phosphate electrolyte displays the weakest discharge. Consequently, the resulting surface porosity reaches up to 9.1% for PEO-Si coating, 6.5% for PEO-Al coating, and 4.9% for PEO-P coating. Phase analysis reveals that coatings generated in aluminate and silicate electrolytes tend to consist of crystalline alumina and mullite, whereas the coating formed in phosphate electrolyte predominantly contains amorphous phases and some crystalline mullite. The electrochemical tests demonstrate that the anti-corrosive ability of the coatings follows the order of PEO-Al > PEO-Si > PEO-P. The electrical insulation protection performance of the three coatings is PEO-Al > PEO-Si > PEO-P under comprehensive consideration.

Contribution of water erosion to organic carbon and total nitrogen loads in agricultural discharge from boreal mineral soils

While organic carbon (OC) in agricultural mineral soils is widely studied in terms of soil carbon sequestration and gaseous emissions, discharge-induced OC loss from soil is still poorly understood and estimations of boreal soil OC loads within water erosion are lacking. Loss of organic matter from arable soils is a concern for surface water quality, climate change and soil productivity. The main aim of this study was to quantify the role of water erosion in total OC and nitrogen (N) loads exported in agricultural discharge from boreal mineral soils under various cultivation practices. Surface water and subsurface drainage were collected near-continually over 2 years in two clayey and one sandy soil in Finland. Eroded sediment was mechanically separated by centrifugation from all discharge samples to detect sediment OC% and N% by dry-combustion method. Dissolved OC and N concentrations in selected discharge samples were measured with high-temperature catalytic oxidation of unfiltered supernatant. A multiple linear regression model was used to study the significant factors affecting dissolved, sediment and total OC loads. In the clayey soils, the sediment OC (2–24 kg ha−1 y−1) and N (0.2–1.1 kg ha−1 y−1) export accounted for up to 35 % and 20 % of the annual discharge-induced total loads of OC (19–85 kg ha−1) and N (2–8 kg ha−1), respectively. In the sandy soil, erosion was negligible and dissolved loads of 17–35 kg OC ha−1 y−1and 4–7 kg N ha−1 y−1 were detected. Subsurface drainage exported most of the sediment-associated OC and N loads from clayey soils. For the total OC loads, the distribution varied between the discharge routes, while the total N loads were mostly exported in subsurface drainage in both soil types. Sediment OC and N exports were related to soil plowing and discharge intensity, while dissolved OC loss was promoted by high surface soil OC%. Our results also indicated that a single cultivation practice may affect sediment and dissolved loads in opposite ways. These findings can be used to complement carbon budget estimations for mineral agricultural soils, and to assess soil management effects on terrestrial organic matter loading to boreal surface waters.

Agricultural activity on the Mun River basin: insight from spatial distribution and sources of dissolved rare earth elements in northeast Thailand.

Rare earth elements (REE) are emerging pollutants of concern, impacted by intensive fertilizer use and discharge of human and animal waste into agricultural watersheds. However, the natural values and potential anthropogenic enrichment of REE in aqueous systems of the agricultural basins remain poorly understood. This study investigated the spatial variation of dissolved REE in a predominantly agricultural river (Mun River) in northeast Thailand. Dissolved ΣREE concentrations in the Mun River ranged from 5.08 to 272.91 ng/L, with the highest concentrations observed in the middle reaches where agricultural fertilizers and wastewater increased dissolved REE concentrations. The PAAS-normalized patterns and dissolved Eu anomaly jointly reveal that the dissolved ΣREE mainly originated from local rocks and agricultural fertilizers. The dissolved REE in the Mun River is characteristic of a depleted light REE relative to heavy REE, slightly negative Ce anomaly, positive Eu anomaly, and positive Gd anomaly in a punctate distribution. The correlation analysis of (La/Yb)N with fluvial pH and HCO3- indicates that the water environment characteristics of the Mun River control dissolved REE fractionation. The Ce anomaly is associated with the oxidation environment, whereas the Eu anomaly is linked to the lithologic inheritance. Positive punctate Gd anomalies are influenced by human-caused wastewater discharge and applying fertilizers, raising Gd concentrations beyond natural background levels. This study has suggested that the geochemical characteristics of dissolved REE are affected by agricultural disturbances, and future environmental research on dissolved REE is essential to clarifying the impacts of REE on agriculture, the environment, and human health.

Enabling Jet-Electrochemical Discharge Machining on Niobium-Like Passivating Metal and the Single Step Fabrication of Coated Microstructures

Analogous to difficult-to-cut materials in mechanical machining, Niobium (Nb) is a difficult-to-dissolve metal by electrochemical machining (ECM) due to its prone-to-passivation nature. Jet-electrochemical discharge machining (Jet-ECDM), which uses anodic discharge rather than the cathodic discharge as in traditional ECDM, has been previously demonstrated as an efficient method for machining inert semiconductors like Si, 4H-SiC. However, applying Jet-ECDM on Nb-like passivating metal is very challenging because plasma electrolytic oxidation (PEO) is very prone to occur in the machining area due to anodic discharges, forming an insoluble, highly stable oxide coating that prevents material removal. This study reveals the principles of overcoming PEO to enable Jet-ECDM on metals. The findings show that the discharge intensity, affected by the electric field and pulse frequency, is decisive in achieving Nb material removal. The electrolyte chemistry significantly influences material removal fashions, depending on the electrolyte’s chemical activity. NaOH is the preferred choice for higher removal efficiency (maximum 1.92 mm min−1) and machining localization, while NaCl ensures better surface quality (Sa 99.4 nm). Moreover, the Jet-ECDM generated microstructure surface presents a thin layer of PEO coatings (<1 μm). This demonstrates the high potential of Jet-ECDM technology for efficient fabrication of coated microstructures in a single-step process.

Impact of submarine karst sulfur springs on benthic foraminiferal assemblage in sediment of northern Adriatic Sea

PurposeThis work highlights the sedimentary characteristics and the role of submarine sulfur-rich karstic springs in the distribution of benthic foraminifera in the northern part of the Adriatic Sea (Bay of Koper). Little is known about how local conditions such as temperature and sulfur bursts may influence sediment properties, benthic habitat variability, and composition of foraminiferal assemblages. Here we compare the distribution of total and living benthic assemblages in surface sediment samples collected from a funnel-shaped depression created by submarine sulfur springs.Materials and methodsSampling was performed at water depths between 24.6 and 32.2 m in fine-grained sandy silt to silty sand (partially washed). Sedimentological, mineralogical, and geochemical analyses of the sediment were carried out and the distribution of benthic foraminifera living around the springs was studied.Results and discussionIn general, sediment characteristics (i.e., mineralogical, geochemical, and organic content) around the sulfur springs do not show prominent deviations from the marine surface sediment of the area; however, some differences exist among depressions of different depths. Deeper depressions in the lower parts probably extend to older continental sediments of Late Pleistocene age with alluvial features, while shallower depressions were formed entirely in Holocene marine sediments typical of a wider area. Only one of the five samples (M05) contained living foraminifera in sufficient abundance for biocenosis research. The benthic foraminiferal assemblages of moderate diversity are composed of opportunistic species. Elphidium translucens, Ammonia ex gr. tepida, Haynesina depressula, and Porosononion granosum dominate, while A. neobeccarii, Reussella spinulosa, and Textularia bocki are subordinate.ConclusionsThe distribution and diversity of foraminifera in the sediment near sulfur springs can be explained by several factors and their interactions. The intensity of the spring discharge affects the mixing/oxygenation of the sediment, the shape of spring depressions, and the granulometry of the coarser sediment around the springs. Sediment characteristics indicate different types of sediment origin. This is related to and can be explained by the depth of spring depressions.

Cortical somatosensory evoked potential amplitudes and clinical outcome after cardiac arrest: a retrospective multicenter study

ObjectiveBilaterally absent cortical somatosensory evoked potentials (SSEPs) reliably predict poor outcome in comatose cardiac arrest (CA) patients. Cortical SSEP amplitudes are a recent prognostic extension; however, amplitude thresholds, inter-recording, and inter-rater agreement remain uncertain.MethodsIn a retrospective multicenter cohort study, we determined cortical SSEP amplitudes of comatose CA patients using a standardized evaluation pathway. We studied inter-recording agreement in repeated SSEPs and inter-rater agreement by four raters independently determining 100 cortical SSEP amplitudes. Primary outcome was assessed using the cerebral performance category (CPC) upon intensive care unit discharge dichotomized into good (CPC 1–3) and poor outcome (CPC 4–5).ResultsOf 706 patients with SSEPs with median 3 days after CA, 277 (39.2%) had good and 429 (60.8%) poor outcome. Of patients with bilaterally absent cortical SSEPs, one (0.8%) survived with CPC 3 and 130 (99.2%) had poor outcome. Otherwise, the lowest cortical SSEP amplitude in good outcome patients was 0.5 µV. 184 (42.9%) of 429 poor outcome patients had lower cortical SSEP amplitudes. In 106 repeated SSEPs, there were 6 (5.7%) with prognostication-relevant changes in SSEP categories. Following a standardized evaluation pathway, inter-rater agreement was almost perfect with a Fleiss’ kappa of 0.88.InterpretationBilaterally absent and cortical SSEP amplitudes below 0.5 µV predicted poor outcome with high specificity. A standardized evaluation pathway provided high inter-rater and inter-recording agreement. Regain of consciousness in patients with bilaterally absent cortical SSEPs rarely occurs. High-amplitude cortical SSEP amplitudes likely indicate the absence of severe brain injury.

Direct decomposition of hydrogen sulfide through microwave-induced discharge of graphitized bio-char

Direct decomposition of hydrogen sulfide (H2S) can be used to obtain high-purity hydrogen, thereby avoiding the waste of hydrogen resources by traditional Claus process. Microwave-induced discharge with spherical bio-char for H2S decomposition is proposed. The bio-char was treated by graphitization modification in presence of microwave heating and iron additive. The influences of graphitization parameters including iron loading and microwave irradiation time on the bio-char graphitization degree were studied. Subsequently, the modified bio-char was applied to induce microwave discharge, and the effects of graphitization parameters on discharge performance were discussed. Lastly, the attention was paid to investigate catalytic effect of microwave-induced discharge with the modified bio-char for H2S decomposition. The results showed the best graphitization degree of bio-char was achieved at iron loading of 6 mmol/g and microwave irradiation time of 60 min. The improvement of bio-char graphitization degree enhanced discharge intensity, thus promoting bed temperature. Microwave discharge exhibited a favorable catalytic effect on H2S decomposition, with initial and ending conversions at 97.4% and 83.2% in a two-hour test, respectively, because of synergistic effect of microwave discharge effect, microwave thermal effect and catalytic activity of the modified bio-char.

Spatial correlation and coupling between industrial enterprise agglomeration and water pollutant discharge

Industrial wastewater discharge has become the main cause of water pollution in China. However, the spatial interaction mechanism between industrial structure and water pollution is still unclear. Accordingly, we evaluated and analyzed spatiotemporal changes of the agglomeration pattern of pollution-intensive industrial enterprises and the evolution of the water environmental pollution pattern, as well as the correlation between them. The study results show that the polluting industrial enterprises were located mainly along the Yangtze River and Taihu Lake Basin in southern Jiangsu in 2013 and 2018. However, we observed a spatial trend of pollution transfer to northern Jiangsu. The industrial water pollution discharge presents the distribution pattern of facing rivers, seas, lakes and cities. Papermaking and paper products industry are the leading factors of COD and NH3–N pollution, with explanatory power of 0.3666 and 0.6201 respectively. The spatial positive coupling effect between the concentration degree of polluting enterprises and the intensity of water environment pollution discharge is 94.95% of the region. The spatial agglomeration of polluting industrial enterprises is an important cause of water environment pollution. They promote and couple each other, proving the existence of “Pollution haven” and “Porter hypothesis".

Analysis of the Plasma Discharge Phenomena for Ceramic Metal Halide Lamps Using Finite Element Method

Metal halide (MH) lamps comes under the category of high intensity discharge (HID) lamps, which involves high intensity thermal plasma discharge phenomenon. In this paper we have considered ceramic MH lamps. The plasma discharge in MH lamps is different from other plasma discharge by the velocity of all the discharge obeys Maxwellian distribution, the excited energy states are occupied by Boltzmann distribution, and composition of the plasma can be derived from local chemical equilibrium. This paper explores the temperature distribution and the immediate effects towards the life of MH lamp. The temperature profile for the MH lamp is numerically investigated using WELSIM 2.0, considering the lamp plasma model mathematical equations. Since electrode plays a significant role, influencing MH lamp life, it becomes imperative to understand the electrodes. In this context, the energy balance equation is taken into consideration. The equations are solved using finite element method. The necessary boundary condition for solution of the equation is the plasma boundary layer for the cathode heat conduction. The analysis provides the temperature distribution inside the lamp for different electrode geometry. The solutions to the equations have been pictorially investigated for the lamp starting phenomena and E/N ratio. For HID lamps in general, the improvements in HID technology are all linked to the performance of the arc tube, and within that tube, the chemical reaction, the pressure, and the temperature of the reaction. Another feature in the case of MH lamps that is worth mentioning in the determination of lamp life is the ratio between electric field to gas number density. From the above, we can draw the following conclusion that the radiation transport mechanism of the HID lamps plays a pivotal role apart from other parameters influencing the lifetime of HID lamps. The paper envisages all these aspects using PDEs, the solutions of which provide an insightful understanding of the phenomena substantially.

Algorithmic fairness and bias mitigation for clinical machine learning with deep reinforcement learning.

As models based on machine learning continue to be developed for healthcare applications, greater effort is needed to ensure that these technologies do not reflect or exacerbate any unwanted or discriminatory biases that may be present in the data. Here we introduce a reinforcement learning framework capable of mitigating biases that may have been acquired during data collection. In particular, we evaluated our model for the task of rapidly predicting COVID-19 for patients presenting to hospital emergency departments and aimed to mitigate any site (hospital)-specific and ethnicity-based biases present in the data. Using a specialized reward function and training procedure, we show that our method achieves clinically effective screening performances, while significantly improving outcome fairness compared with current benchmarks and state-of-the-art machine learning methods. We performed external validation across three independent hospitals, and additionally tested our method on a patient intensive care unit discharge status task, demonstrating model generalizability.

Projected changes in annual maximum discharge for Iowa communities

Understanding the projected changes in annual maximum peak discharge is important to improve resiliency in water resource planning and design at the community level. Currently, much of the literature on climate change impacts focuses on analyses at the regional scale. In this study we use a hydrologic model to evaluate the projected changes in annual maximum peak discharge at the community-level across Iowa under two emission scenarios, Representative Concentration Pathway 4.5 and 8.5 (RCP4.5 and RCP8.5). We utilize climate forcings from global climate models part of the Coupled Model Intercomparison Projected Phase 5 (CMIP5) from 1950 to 2100. Our simulations show a detectable increase in annual maximum discharge for 27% of Iowa’s communities under RCP8.5. However, under RCP4.5 none of the communities are projected to face an increase in annual maximum discharge by the end of the 21st century; furthermore, precipitation intensity under this scenario is not projected to increase in the latter half of the 21st century. Our results point to a larger increase in precipitation intensity and annual maximum discharge under RCP8.5 compared to RCP4.5, especially in the second half of this century. The projected flood peak distributions tend to become statistically different from the historical ones later in the 21st century under RCP8.5 than under RCP4.5. This study provides a basis for analyzing climate change impacts at a local decision-making scale.

Trends in severe outcomes in SARS-CoV-2-positive hospitalized patients with rheumatic diseases: a monocentric observational and case-control study in northern Italy.

Rheumatic disease patients are at greater risk of infection due to their disease, comorbidities, and immunosuppressive therapy. COVID-19 outcomes in this patient setting appeared to be similar to those of the general population. However, data on this topic were mainly related to small studies on a limited number of patients. Consequently, to date, this field remains poorly explored, particularly in the pre-vaccine era. This monocentric study aimed to describe the intrahospital mortality in rheumatic patients with SARS-CoV-2 consecutively hospitalized from 21 February to 31 December 2020, before anti-SARS-CoV-2 vaccine administration spread, compared with non-rheumatic patients. Of 2491 included patients, 65 [3%, median (interquartile range) age 75 (64.76-82.239 years, 65% women] were suffering from rheumatic diseases. A total of 20 deaths were reported [case fatality rate 31%, 95% confidence interval (CI): 19-42] compared with 433 deaths (19%, 95% CI: 17-20) in patients without rheumatic diseases (p=0.024). However, the rheumatic disease was not associated with a significant increase in univariate mortality hazards (hazard ratio 1.374, 95% CI: 0.876-2.154), and after adjustment (hazard ratio 1.199, 95% CI: 0.759-1.894) by age, sex and Charlson comorbidity index. The incidence of intensive care unit admission, death, and discharge in the case-control study was comparable between rheumatic and non-rheumatic patients. The presence of rheumatic diseases in SARS-CoV-2-hospitalized patients did not represent an independent risk factor for severe disease or mortality.

Exceeding Turbidity versus Karst Spring Discharge during Single Rainfall Events: The Case of the Jadro Spring

The relationship between karst spring discharge and turbidity during periods where the turbidity exceeds the permitted value of 4 NTU is analyzed by means of classical hydrological methods including hysteresis loops. The Williams method (1989) is adjusted by replacing river discharge with karst spring discharge, and sediment concentration with exceeding turbidity. The study’s first part focuses on the general hydrological characteristics of cumulative rainfall, turbidity, and discharge during each period. In the second part, four major types of hysteresis loops are identified, classified, and hydrologically explained. The study area is the karst catchment of the Jadro Spring in Croatia. The obtained results show that hysteresis loops can be very useful in analyses of water turbidity from karst springs. A relationship between the type of loop, intensity of discharge, and size of the secondary peak in turbidity is identified. The major types of hysteresis loops were clockwise, counterclockwise, figure-eight and complex loops, and their main characteristics were summarized. The results gave a new insight into the behavior of the turbidity of the Jadro Spring.

Exploring the contribution of the river chief system on controlling industrial water pollution under quasi-natural experimental conditions.

The innovative environmental system known as the river chief system (RCS) was developed in China to limit water pollution by appointing provincial, prefectural, county, and township officials as "river chiefs" as guardians of every river under their control. Our research project developed a quasi-natural experiment to investigate if the RCS effectively reduces the intensity of industrial water pollution. A multi-period difference-in-difference (DID) method was employed in the experiment with a total of 3808 samples from 272 prefecture-level cities. The samples gathered represented the years from 2007 to 2020. Our results demonstrated that the southern region has far more industrial water contamination than other locations, and the intensity of industrial sewage discharge decreased by 10.25% in pilot cities following the implementation of the RCS compared with what we observed in non-pilot cities. Furthermore, according to the mechanism analysis we used, cities that increased investment in technical advancement and modernized industrial structures may also account for this decreasing trend. Additionally, the results of geographical heterogeneity demonstrate that the RCS's influence on curbing industrial water pollution is greater in cities with a higher intensity of environmental regulation and higher fiscal balance pressure than in locations with low environmental regulation and low fiscal balance pressure. In summary, the Chinese government needs to continue to strengthen the RCS's implementation; this can be done by adjusting to local circumstances as needed and by carrying out the policy accurately and effectively across the country. Our research sheds light on how to prevent water pollution in China and in other countries and supports the positive effects and effectiveness of RCS.

Compared discharge characteristics and film modifications of atmospheric pressure plasma jets with two different electrode geometries

Atmospheric pressure plasma jet shows great potential for polymer film processing. The electrode geometry is the key factor to determine discharge characteristics and film modification of jets. In this paper, we compared the discharge characteristics and the film modifications of atmospheric pressure plasma jets with needle-ring electrode (NRE) and double-ring electrode (DRE). The results show that jet with NRE has stronger electric field intensity and higher discharge power, making it present more reactive oxygen particles and higher electron temperature, but its discharge stability is insufficient. In contrast, the jet with DRE has uniform electric field distribution of lower field intensity, which allows it to maintain stable discharge over a wide range of applied voltages. Besides, the modification results show that the treatment efficiency of PET film by NRE is higher than that by DRE. These results provide a suitable atmospheric pressure plasma jets device selection scheme for polymer film processing process.

Optimal discharge of patients from intensive care via a data-driven policy learning framework

Clinical decision support tools rooted in machine learning and optimization can provide significant value to healthcare providers through better management of intensive care units. In particular, it is important that intensive care unit patient discharge decisions account for the nuanced trade-off between decreasing the length of stay and the risk of readmission or death after discharge of a patient. This work introduces a comprehensive framework (i.e., not geared towards any particular disease or condition) for capturing this trade-off and to recommend optimal discharge timing decisions given the electronic health records of a patient. A data-driven approach is used to derive a parsimonious, discrete state space representation to represent the physiological condition of a given patient. Based on this model and a given cost function, an infinite-horizon discounted Markov decision process is formulated and solved numerically to compute an optimal discharge policy, whose performance is assessed using off-policy evaluation strategies. Extensive numerical experiments are performed to validate the proposed framework using real-life intensive care unit patient data.

Microplastics distribution in river side bars: The combined effects of water level and wind intensity

Rivers are the main pathway for microplastics (MP) transport toward the ocean. However, the understanding of the processes involved in the deposition and mobilization of MP in rivers, specifically in sediment side bars (SB), remains very limited. The objectives of this study were: (i) to examine the effect of hydrometric fluctuations and wind intensity on the distribution of microplastics (MP < 5 mm) in the SB of large river (the Paraná River), (ii) to determine the characteristics of MP to infer their origin and fate, and (iii) to discuss potential similarities or differences between MP suspended in the water column and MP found in sediment. The SB and water column were sampled during the autumn, winter, and spring of 2018, and the summer of 2019 at different river discharges and wind intensities. >90 % of the MP items found were fiber of polyethylene terephthalate (PET; FT-IR analysis), the most common MP color was blue, and most were in the 0.5–2 mm size range. The concentration/composition of MP varied according to the river discharge and wind intensity. During the falling limb of the hydrograph when discharge is decreasing and sediments are exposed for short periods (13–30 days), MP particles transported by the flow were deposited on temporarily exposed SB, accumulating there in high densities (309–373 items/kg). However, during the drought, when sediments remained exposed for a long time (259 days), MP were mobilized and transported by the wind. During this period (no influence of the flow), MP densities significantly decreased on SB (39–47 items/kg). In conclusion, both hydrological fluctuations and wind intensity played a significant role in MP distribution in SB.

Implementation of Rapid Genome Sequencing for Critically Ill Infants With Complex Congenital Heart Disease.

Rapid genome sequencing (rGS) has been shown to improve care of critically ill infants. Congenital heart disease (CHD) is a leading cause of infant mortality and is often caused by genetic disorders, yet the utility of rGS has not been prospectively studied in this population. We conducted a prospective evaluation of rGS to improve the care of infants with complex CHD in our cardiac neonatal intensive care unit. In a cohort of 48 infants with complex CHD, rGS diagnosed 14 genetic disorders in 13 (27%) individuals and led to changes in clinical management in 8 (62%) cases with diagnostic results. These included 2 cases in whom genetic diagnoses helped avert intensive, futile interventions before cardiac neonatal intensive care unit discharge, and 3 cases in whom eye disease was diagnosed and treated in early childhood. Our study provides the first prospective evaluation of rGS for infants with complex CHD to our knowledge. We found that rGS diagnosed genetic disorders in 27% of cases and led to changes in management in 62% of cases with diagnostic results. Our model of care depended on coordination between neonatologists, cardiologists, surgeons, geneticists, and genetic counselors. These findings highlight the important role of rGS in CHD and demonstrate the need for expanded study of how to implement this resource to a broader population of infants with CHD.

Development of an atmospheric fluorocarbon plasma jet generated by pulse modulated microwave discharge

Atmospheric fluorocarbon plasma plays an important role in the surface modification of insulating materials like polymers. The existing fluorocarbon plasma is usually generated by dielectric barrier discharge, which has a low concentration of reactive species and may cause insufficient surface fluorination. This work attempts to develop an atmospheric fluorocarbon plasma jet using a coaxial transmission line resonator by microwave discharge with locally enhanced electric field and high density. The gas temperature is reduced by pulse modulation technology. Three kinds of working gases, pure CF4, Ar/CF4 and He/CF4, are utilized to generate the atmospheric microwave fluorocarbon plasma jet. The discharge images, optical emission spectra, electron densities and gas temperatures are studied experimentally. The results show that the Ar/CF4 plasma jet has the best comprehensive performance, such as strong discharge intensity and controllable gas temperature. The electron density of the Ar/CF4 plasma jet has a magnitude of 1020 m−3, indicating a higher density than that of the frequently used dielectric barrier discharge. With the other conditions unchanged, the gas temperature at the end of the Ar/CF4 plasma jet can be reduced from 410.2 to 347.3 K by decreasing the duty cycle of the modulated pulse from 0.5 to 0.1. Thence, the microwave Ar/CF4 plasma jet is considered to be a promising fluorocarbon plasma source for surface fluorination of polymers.