TEC Values Research Articles

Characterization of A-site doped PrBaCo2O5+δ perovskites as cathode materials for IT-SOFCs

Creating highly efficient and durable cathodes persists as a formidable task in the realm of intermediate temperature solid oxide fuel cells (IT-SOFCs). Hence, we present a double perovskite oxide, Pr0.6Sr0.4BaCo2O5+δ (PS0.4BC), and its electrocatalytic activity is thoroughly investigated. The XRD test is carried out and a notable transformation in the phase structure is observed upon the introduction of Sr2+ ions into the PBC matrix. That is, the phase structure of the material changes from double perovskite structure to single perovskite structure. Through the TG and TEC test that the introduction of Sr2+ ions into the lattice can create additional sites for oxygen vacancy formation and reduce TEC values. Further verify that Sr doping can enhance the concentration of oxygen vacancies of the material. The PS0.4BC cathode material exhibits remarkably low polarization resistance, achieving an impressive value of 0.027 Ω cm2 at an operating temperature of 800 °C. Oxygen partial pressure test shows that as the oxygen partial pressure decreases, there is a notable increase in impedance, particularly evident in the low frequency region of the Nyquist plots. This indicates that the oxygen content has obvious effects on the low-frequency processes. When the oxygen partial pressure exceeds 0.05 atm, the oxygen adsorption-dissociation and diffusion process is the rate-limiting step in the ORR. However, when the oxygen partial pressure is less than 0.05 atm, the formation of lattice oxygen through the combination of oxygen ions and oxygen vacancies processes is the rate-limiting step. Compared PBC cathode material, the more pronounced changes in the high frequency arc of the PS0.4BC cathode at the same oxygen content. It shows that Sr doping significantly changes the high frequency process. After doping, the oxygen vacancy concentration increases, which facilitates the occurrence of the charge transfer process at high frequency.

Combinational Toxic Effect of Insecticide and Fungicide on Hematological Indicators in Mice

Exposure to two or more compounds in a living system may result in unexpected outcomes. The present study was planned to investigate the effect of two pesticides, Imidacloprid (IMI) and Carbendazim (CBZ), when exposed alone and in combination, on hematological indicators. All mice were equally divided into six different groups consisting of normal control, IMI-L & IMI-H (45.5 & 90.0 mg/kg feed, respectively), CBZ-L & CBZ-H (1.4 and 2.8 g/kg feed, respectively) alone, and in combination (IMI-L+CBZ-L). Blood was collected, and hematology was performed upon completion of the 28-day feeding period. Results revealed that exposure to IMI and CBZ did not show apparent signs and symptoms of toxicity except for the IMI high dose alone. The net average feed and water consumption per mouse were comparatively less in the IMI-H and CBZ-H groups compared to the control group. A dose-dependent significant change (p<0.05) in TLC, TEC, PCV, and Hb values was noticed in treatment groups. Non-significant changes (p>0.05) in the percent lymphocyte, eosinophil, and monocyte were noticed between all the treatment groups. No significant change (p>0.05) in the values of Hb, PCV, MCV, and MCH of the IMI-L+CBZ+L treated group was noticed when compared with the respective IM-L and CBZ-L groups. A non-significant change (p>0.05) in studied parameters was noticed when compared between IMI-L+CBZ-L treated groups with corresponding CBZ-L and IMI-L alone treatment groups. Based on the interactive index, the study concluded that a combination of IMI and CBZ exposure via the dietary medium has no definitive additive or synergistic toxic effect on hematological indicators.

Efficacy of thankuni and grapes in arsenicosis-affected rat

This study was undertaken to observe the effects of Thankuni and grapes on hematological and biochemical parameters against arsenicosis in Long Evans rats. Sixty male rats were selected to perform the study. The experimental rats were randomly divided into five different groups, with n = 12 in each group. Animals in group T0 were given normal feed and water and kept as control. Rats of group T1 were given arsenic trioxide @ 100 mg/L of drinking water orally. Rats of group T2 were given arsenic trioxide @ 100 mg/L drinking water and Thankuni @ 1gm/kg feed. Group T3 was given arsenic trioxide @ 100 mg/L drinking water with grapes @ 10 mg /kg body weight thrown DW. Group T4 was given arsenic trioxide, Thankuni, and grapes with the same dose for up to 45 days, respectively. Four randomly selected rats from each group (T0, T1, T2, T3, and T4) were sacrificed at 15-day intervals to determine body weight, hematological and biochemical parameters. At the end of the experiment, the result showed that the minimum weight gain group was T1 whereas the maximum weight gain was found in the T3 and T4 groups. The weight gain of the T2 group is better than T1. Reduction of TEC and Hb values were significant (P < 0.01) in the T1 group. Whereas in the rest of the groups, the reduction of TEC and Hb was less than in arsenic-treated groups. In conclusion, Thankuni and grapes have a significant effect on body weight and hematological and biochemical parameters.

Improvement of topside ionosphere and plasmasphere estimation in ionospheric simulation system

This work is based on the results for a complete solar cycle of 11 years (2011–2021) from the ionospheric simulation system used in the Brazilian Space Weather program. The electron density profiles generated were integrated in height and compared to the International GNSS Service (IGS) vertical total electron content (vTEC) data. Experiments have shown an inadequate electron concentration decay with height which led to an overestimation in TEC values. We propose an improvement for the topside ionosphere and plasmasphere modeling in the system, considering recent advances in empirical modeling through observational data. The idea is to combine bottomside ionosphere estimates from the physical-based core model with NeQuick analytical formulation for ionospheric profile above hmF2. Our approach also calculates the ionospheric parameters for topside modeling using bottomside estimates. The ionospheric density profile decay obtained with the proposed approach was smoother and sharper, reaching a reduction of approximately 1 to 2 orders of magnitude of electron concentration in plasmasphere. It was observed a coherent reduction of high altitudes ionosphere/plasmasphere contribution to TEC. Also, the TEC values obtained using this hybrid solution were much closer to the International GNSS Service (IGS) data for the considered dataset, with root mean squared error (RMSE) of only 2.64 TECU for the entire period.

TEC variations and IRI-2016, IRI-2020 and IRI-Plas performance in Mexico

The present work discusses TEC variations over Mexico and their representation by the advanced ionospheric models IRI-2016, IRI-2020 and IRI-Plas during the years of low and increasing solar activity, 2018–2022. The statistical estimates Mean Absolute Error (MAE), Root Mean Square Error (RMSE) and Normalized Root Mean Square Error (NRSME) were used to assess model performances. The earlier revealed TEC features were confirmed and new features were revealed. The hour of the diurnal TEC maximum varies in a wide range within 10–20 LT. In summer, it occurs at earlier hours than in other seasons. During the solar minimum, the annual variation (two minima and two maxima during a year) was found absent and a seasonal dependence of the lowest night TEC value is revealed. The accuracy of TEC representation depended on the model, hour of the day, season and solar activity level and suffered a notable change in 2022. In the considered period, IRI-2016 overestimated the daytime and underestimated the nighttime TEC in most cases. Essentially, IRI-2016 and IRI-2020 gave similar results. IRI-Plas overestimated the daytime TEC during the low solar activity and mostly gave adequate estimates at night. Its accuracy at day hours increased with the growth of solar activity. Quantitative estimates of the accuracy of the models are as follows. The yearly average of RMSE for IRI-2016 and IRI-2020 was minimal in 2018 and maximal in 2022. In contrast, for IRI-Plas it was minimal in 2022 and maximal in 2021. At nighttime, RMSE typically varied as follows. For IRI-2016, within (1–5) TECU during low and within (2–12) TECU during increasing solar activity; for IRI-2020 within (1–3) TECU and (1–9) TECU; and for IRI-Plas within (0.5–4) TECU and (2–9) TECU, respectively. At daytime, RSME were higher: for IRI-2016 within (4–11) TECU under low and (6–19) TECU under increasing solar activity; for IRI-2020 (4–9) TECU and (4–17) TECU; and for IRI-Plas (10–19) TECU and (6–15) TECU, respectively. The discrepancies between the modeling results and observations at low latitudes are due to the poor representation of EIA structures and topside and plasmaspheric parts in TEC. TEC annual variation is always represented by the models, but, it was practically absent during the solar minimum according to the experimental results.

Surrogate model-based optimization of methanol synthesis process for multiple objectives: A pathway towards achieving sustainable development goals

This work combines a generalized regression neural network (GRNN) with a non-dominated sorting genetic algorithm (NSGA-II) to optimize a methanol synthesis plant for multiple objectives. The proposed method begins by developing and validating the model for the methanol synthesis involving the recycling of unreacted gas stream into the methanol reactor feed. The data generated using this model is used to develop a GRNN-based surrogate model to expedite the evaluation of fitness values for the optimization algorithm. The objective functions considered for simultaneous optimization are minimizing the total energy cost per unit of energy input (TEC), maximizing overall resource utilization (R), and minimizing CO2-gram equivalent emissions per unit of energy input (EPEI). Pareto optimal solutions are obtained for three bi-and one tri-objective optimization case studies using the GRNN-assisted multi-objective optimization (GRNNAMOO) method. The developed GRNNAMOO approach reduces the computational time from multiple days to a few seconds for all case study scenarios. For the tri-objective optimization case, the operating point selected using multi-criteria decision-making achieves 84.37% of R, 10.45 $/GJ of TEC, and an EPEI value of 81.34 gCO2eq/MJ. These results represent 7.05% higher R, 0.34 $/GJ lower TEC, and 0.82 gCO2eq/MJ lower EPEI than the Aspen plus simulation results. Further, the carbon footprint values obtained are significantly lower than 110 gCO2eq/MJ reported for modern methanol plants for nearly the same R and TEC values. The proposed approach aligns with the United Nations' sustainability development goals by lowering energy costs and promoting sustainable energy through improved environmental sustainability in methanol production plants.

Assessment of the accuracy of IRI-2016 model at the equatorial-, low-, mid-, and high-latitudes ionosphere along 30–45oE meridian lines during minimum (2009) and maximum (2013) phases of solar cycle 24

This study assesses the accuracy of the International Reference Ionosphere IRI-2016 model prediction at the equatorial-, low-, mid-, and high-latitude ionosphere along 30–45oE meridian during minimum (2009) and maximum (2013) phases of solar cycle 24. We used raw TEC derived from GPS observation data from GPS receivers within ∼±70o latitudinal band, along the African/European longitudinal sector. We compared the GNSS-TEC data after the Plasmaspheric Electron Content (PEC) has been excluded with those derived from the two components of the IRI-2016 model. The percentage contributions of PEC to GNSS-TEC was minimum in June solstice, and maximum in December solstice with the highest values at the high-latitude regions, but with a clear hemispherical asymmetry; manifesting the winter anomaly effect. Higher TEC values were recorded in the equatorial/low-latitude regions than in the high- and mid-latitude regions. Overall, in both hemispheres, the accuracy of prediction of the IRI-2016 model was higher in the high- and mid-latitude regions than in the equatorial/low-latitude regions. The accuracy of the model was higher during solar minimum than during solar maximum. Both options of IRI-2016 performed better at nighttime than during daytime. IRI-NeQuick option generally performed better than the IRI-Corr option. TEC values were higher in the southern hemisphere than in the northern hemisphere.

Exposure to tobacco (Nicotiana tabacum) extract and cigarette smoke induces hematological and histopathological alterations in Swiss albino mice

Tobacco smoking is a widely practiced recreational activity and is associated with numerous health risks. Hence, the present study was conducted on Swiss albino mice to assess the impact of aqueous extract of tobacco and cigarette smoke on behavioral, hematological, and histopathological parameters of the lungs, liver, and kidney. The mice were divided into Control (Cont), Tobacco nicotiana (TN), and Cigarette smoke (CS) groups (n=6). TN group received aqueous tobacco orally at a dose of 5ml/kg BW for 21 days, whereas CS group was exposed to inhalational commercial cigarette smoke for the same duration. On day 22, blood samples and visceral organs were collected to evaluate hematological (TEC, TLC, Hb%) and histopathological parameters from euthanized mice. The TEC values were significantly elevated (P<0.05) in both groups. In contrast to the control group, the TLC value was lower in the CS group (P>0.05) than in the TN group, but the mean Hb% values showed no significant changes. Lower body weight, aggressive behavior, and weakness were observed in the treated groups. Histopathologically, the lung revealed emphysematous changes, alveolar septal thickening, inflammatory cells infiltration, congestion, and thrombus formation in pulmonary artery. Liver exhibited hepatocyte degeneration with karyomegaly and karyorrhexis, derangement of hepatic cords and sinusoids with central vein congestion. Derangement of renal tubules, edema, and glomerular degeneration observed in the kidney. These observations lead us to postulate that tobacco and cigarette smoke exert detrimental effects on the structure of some vital organs in the body after direct or indirect uptake.

Lower Ionospheric variations during the intense tectonic activity in the broader area of Greece on October of 2020

In this paper, we investigate the Lower ionospheric variations from TEC observations during the intense seismic activity of October 2020 in the area of Greece. The data were analysed using both, statistical analysis of TEC variations in order to detect uneven gross variations and Discrete Fourier analysis in order to investigate the TEC turbulence. The results of this investigation indicate that the High-Frequency limit fo of the ionospheric turbulence content, increases as aproaching the occurrence time of the earthquake, pointing to the earthquake epicenter, in accordance with our previous investigations. We conclude that the Lithosphere Atmosphere Ionosphere Coupling, LAIC, mechanism through acoustic or gravity waves could explain this phenomenology. In addition, the statistical analysis shows an excess greater than 3𝜎 from the mean TEC values, one and seven days before the earthquake. Since no major disturbance of the geomagnetic field occured during these days, we conclude that we probably observed precursory ionospheric variations in accordance to analogous findings from the variation of VH/VHF electromagnetic wave propagrations over strong earthquake areas.

Evaluation of Haemato-biochemical Effects of Tiletamine-zolazepam Alone and in Combination with Xylazine or Xylazine-ketamine in Atropinized Dogs

Background: Tiletamine-zolazepam is a good injectable anaesthetic widely used in veterinary patients and thus the present study was planned to evaluate the effect of tiletamine-zolazepam alone and in combination with xylazine and xylazine-ketamine in dogs. Methods: Eighteen dogs irrespective of age, breed, sex and body weight (requiring various surgical corrections) were randomly divided into three groups namely A, B and C. Atropine sulphate was administered in all the groups followed by tiletamine-zolazepam in group A, xylazine and tiletamine-zolazepam in group B and xylazine, ketamine and tiletamine-zolazepam in group C. The efficacy of the anaesthesia was evaluated at different time intervals upto recovery by observing clinical, physiological and haemato-biochemical parameters. Result: Induction dose of tiletamine-zolazepam observed in group A, B and C was 6.5, 5.5 and 4.0 mg/kg body weight, respectively. Induction time values were decreased and duration of anaesthesia was increased from group A to group C. All physiological parameters differs significantly (p less than 0.05) between the groups. Mean values of Hb, TEC, PCV, TLC, lymphocytes, monocytes, eosinophils, basophils and total proteins showed transient decrease whereas neutrophils, ALT, AST, total bilirubin, plasma glucose, BUN and serum creatinine showed transient increase in all the groups at 30 and 60 minutes. Haemato-biochemical parameters approached to baseline values upto 24 hours. Thus, it can be concluded that the various combinations of tiletamine-zolazepam with pre-medicants like xylazine and xylazine-ketamine was found to be safe with regard to their effects on haemato-biochemical parameters.

Impact of Different Therapies on Haemtological Parameters and Therapeutic Outcome in Subclinical Endometritic Buffaloes

The objective of this study was to compare the effect of administration of intrauterine dextrose, s/c levamisol and intrauterine PGF2α on haematological indices and therapeutic response in endometritic buffaloes. Twenty eight repeat breeder buffaloes with subclinical endometritis were randomly assigned into four groups. Seven animals were kept as Control (untreated C), and the rests were assigned to three treatment group, i.e., T1 (Dextrose I/Ut, 50 mL 4 times on the day of estrus), T2 (Levamisol s/c, @ 2.5 mg/kg b.wt. on day 0, 7 and 14 of the cycle), and T3 (PGF2α I/Ut, @ 0.25 mg in 0.5 mL saline twice, on the day of first and next estrus). Following treatment the values of Hb, TEC and PCV elevated significantly and TLC values dropped to normal or near normal in all three treatment groups as compared to control group. Furthermore, the post-treatment neutrophils and lymphocytes counts were elevated significantly in all four groups. However, there was no any definite pattern of eosinophils and basophils. The therapeutic response (clinical recovery) was 14.29, 71.43, 85.71 and 42.86 % in T0, T1, T2 and T3 group, respectively. The corresponding conception rates were 0.00, 60.00, 66.67 and 66.67 %. The results conclude that, Dextrose intrauterine, Levamisol s/c, and PGF2α intrauterine can be used effectively to manage subclinical endometrtitis in buffaloes.

Haemodynamic and Haemato-Biochemical Changes with Ketamine, Propofol and Ketofol as Constant Rate Infusion Anesthesia for Elective Ovariectomy in Dogs

Background: Combination of glycopyrrolate, butorphanol, xylazine as premedication and induction with propofol and maintenance with ketamine, propofol and propofol mixtures (Ketofol 1:1) as constant rate infusion (CRI) would have the ability to maintain better hemodynamic and reduce the dose of general anesthesia for maintenance. This technique once gets standardized; it may transfer to field veterinarians for elective ovariectomy under a routine animal birth control programme (ABC) for safe handling of canines. Therefore, the present study was designed to evaluate haemodynamic and haemato-biochemical changes with Ketamine, Propofol and Ketofol as CRI anesthesia in dogs. Methods: The study was conducted on 18 female dogs during 2019-2021 and these animals were randomly divided into three experimental groups, each group (I, II and III) containing six animals. All animals were pre-medicated with glycopyrrolate @ 0.01 mg/kg b.wt I/M followed by inj. butorphanol 0.2 mg/kg b.wt and xylazine 1mg/kg b.wt I/M after 5 minutes by using different syringes. After 10 minutes of xylazine, animals were induced (till effect) with propofol and immediately just after induction animals were maintained with constant rate infusion of ketamine, propofol and ketofol 1:1 along with normal saline @ 10 ml/kg/hr. Result: Cardiovascular parameters showed that the value of systolic arterial pressure increased significantly (P less than 0.05) after pre-medication in all three groups in comparisons to respective base values. Value of diastolic arterial pressure increased significantly (P less than 0.05) after pre-medication in groups I and II, whereas non-significantly (p greater than 0.05) in group III in comparisons to respective base values. Hemoglobin and PCV values decreased non-significantly after pre-medication and remained non-significantly lower at various intervals in comparison to respective base values during observation periods except at recovery in group II. Changes in TLC did not show a definite pattern and values of TEC in all groups changed non-significantly (p greater than 0.05) at various time intervals in comparison to respective base values during the observation period.

Incidence and haematobiochemical study of amphistomosis in buffaloes (Bubalus bubalis) in Mhow, Madhya Pradesh

In the present study, samples from 100 buffaloes of either sex were collected from slaughterhouse located at Cantonment Board Mhow for the detection of ruminal amphistomosis. Blood samples with or without anticoagulant were collected to study the haematobiochemical changes in buffaloes suffered from amphistomosis. Amphistomes were also collected for morphological identification of amphistome species in slaughtered animals. The prevalence of ruminal amphistomes was found to be 8%. The infected buffaloes in this study showed a reduction in the mean values of Hb, TEC and PCV. There was an increase in TLC and neutrophil count. Lymphocytes showed a slight decrease in their mean values and no significant changes were seen in values of basophil and eosinophil count. The infected buffaloes in this study showed a reduction in the mean values of total protein. The mean values of SGOT, SGPT and alkaline phosphatase showed an increment in the infected buffalo.

Drug potency effects of three anthelmintics against natural fascioliasis with hematological values in goat

The purpose of the study was to compare the effectiveness of three anthelmintics against naturally occurring fascioliasis in goats as well as how they affected various hematological values over the course of 28 days. For this investigation, out of 417 goats, 60 were selected who were suffering from liver fluke infection. After being randomly divided into four groups of 15 animals each, the first three groups got treatment with triclabendazole, oxyclozanide, and nitroxynil while the fourth group was kept as a control group and received no medication. The results of the study showed that the egg per gram (EPG) count of the treatment groups significantly decreased successively (P < 0.01) on days 3rd, 7th, 14th, and 28th, whereas the control group produced significantly from day 3rd through the experimental period. Results revealed that the mean EPG was reduced by 78.40 %, 73.33 %, and 83.11 %, respectively, following treatment with triclabendazole, oxyclozanide, and nitroxynil, while the mean EPG production was 22.66 % in the control group. Hematological parameters including Hb, PCV, and TEC values, were lower before the treatment but turned to increase significantly (P < 0.01) on study day 28th, however, the mean TLC values were decreased substantially (P < 0.01) compared to the untreated control group. This result may indicate that all three anthelmintics were efficient, but nitroxynil had a relatively higher efficacy against goat fascioliasis regarding on the EPG and hematological indices.

Spatial and temporal behaviour of Ionospheric VTEC and Atmospheric parameters before New Zealand earthquake on 13th November 2016 (M 7.8)

In this paper, we present the results of the Ionospheric VTEC and atmospheric parameters such as Surface Latent Heat flux (SLHF), air temperature at 2 m from the surface (AT2m) and outgoing long-wave radiation (OLR) during New Zealand earthquake of M 7.8 on 13th Nov 2016 with a focal depth of 15.7 km. GPS data from 16 permanent IGS GPS stations from October 1 to November 19, 2016 are used for VTEC analysis. Global geomagnetic and solar parameters are also taken into account in the corresponding period. Both positive and negative anomalies in VTEC were observed using the Interquartile Sliding Moving Average method. Using the upper bound (UB) and lower bound (LB) of the VTEC time series, we observed a stronger enhancement of UB over the observed VTEC at the closer stations than at the far stations before New Zealand earthquake. We observed two VTEC anomalies 14 days and 2 days before this earthquake. By comparing the quiet days and the earthquake disturbed days, we observed significant deviations of the TEC on the earthquake disturbed days. The latitude variations of VTEC at each 30-min interval on November 13, 2016 clearly show the enhancement of the TEC signal just before the earthquake. TEC values appear to be normal between 00:00 and 04:30, peaking around 08:30 UT until the time of the earthquake (11:03 UT) in the New Zealand region. Atmospheric anomalies were calculated when the signal crossed the mean + 2*sigma; and with additional parameters such as the Excess Energy Flux Index (EEFI). SLHF parameters detected abnormal signal 33 and 18 days before the New Zealand earthquake. On October 18, 2016, the air temperature measured 286.25 °K at 2 m from the surface is 3.05 °K higher than the ten-year average and an “EEFI” of 2.18. The next day (October 19, 2016), the air temperature measured 2 m from the surface was 285.89 °K, while the ten-year mean air temperature at 2 m was 283.12 °K and the EEFI of 2.78. Two days after the second SLHF anomaly and four days before the earthquake (November 9, 2016), the anomalous fluctuations of AT2m for the current earthquake were observed for the second time. From the analysis of atmospheric parameters such as surface latent heat flux (SLHF), air temperature 2 m from the surface (AT2m) and outgoing long-wave radiation (OLR), it is observed that anomalous variations of these parameters were observed near the epicentral region before the New Zealand earthquake. VTEC together with atmospheric parameters (SLHF, AT2m and OLR) prove to be a promising tool for monitoring earthquake precursor signatures just before the New Zealand earthquake.

Haemato-Biochemical Changes after Laparoscopic and Conventional Ovariohysterectomy in Dogs

The present study was conducted on 24 bitches presented for ovariohysterectomy at Veterinary Clinical Complex of the college, Bikaner, India. The animals were randomly divided in two groups. Ovariohysterectomy was performed by conventional method and laparoscopic method in Group A and B, respectively. Physiological and haemato-biochemical parameters were determined in both the groups. The post-operative heart rate, respiratory rate and rectal temperature reduced significantly (p<0.05) as compared to pre-operative values in both the groups. PCV values decreased significantly in animals of both the groups. The difference in TEC and TLC values remained non-significant in both the groups; however, in Group-A animals, significant (p<0.05) increase in TLC values was noticed at 12 to 24 h. Significant (p<0.05) increase in neutrophils and decrease in lymphocytes were recorded, while monocytes and eosinophils remained statistically unchanged during the entire period of time. Significant (p<0.05) increase was observed in the values of blood glucose, cortisol, AST, creatinine, CK, alkaline phosphatase in Group-A and Group-B, however, ALT values remained non-significant in both the group. Increased TLC, neutrophils, serum cortisol, AST and CK for longer duration in animals of Group-A compared to Group-B indicated more inflammation, tissue trauma, muscle damage and stressed conditions in conventional method of ovariohysterectomy.

Tuning geometry distortion of pyrochlore RE2Zr1.95Ni0.05O7+δ anodes with rich oxygen vacancies for ammonia-fed solid oxide fuel cell

Pyrochlore oxide A2B2O7 is a potential anode catalyst of ammonia-fed solid oxide fuel cell (SOFC) due to its unique and open structure that can make some oxygen ions flow to occupy the hole position to form Frankel defect. Herein, various rare-earth ions with different radius are selected as the A site to construct defective pyrochlore oxide RE2Zr1.95Ni0.05O7+δ (REZN, RE = La, Pr, Nd, Sm, Gd, LZN/PZN/NZN/SZN/GZN) to gain insights into oxygen vacancies that can be the diffusion and adsorption active site for ammonia. In the n-type semiconductor REZN, the degree of crystal ordering decreases with the decrease of the radius of rare-earth RE3+ ions. Among them, GZN exhibits the most negative conduction band and the smallest band gap, making it easier to overcome the energy potential barrier and facilitate the movement of carriers. As a result, the conductivity of GZN is about 25 times higher than that of LZN. The average TEC value of GZN is 10.40 × 10-6 K−1, which matches that of electrolyte YSZ (10.50 × 10-6 K−1). The maximum power density of ammonia-fed SOFC supported by YSZ electrolyte based on GZN anode is 128.63 mW·cm−2 at 800 °C, which is 2.3 times higher than that of NiO-based SOFC. The single cell based on GZN anode can be run continuously for 100 h at 800 °C without significant degradation. The preliminary results suggest that GZN oxide is promising to be a candidate catalyst for ammonia-fed SOFC anode.

Observation of Scintillation Enhancements and Large‐Scale Structures Within the Equatorial Ionization Anomaly During a Sudden Stratospheric Warming Event

AbstractTotal electron content (TEC) and L‐band scintillations measured by several networks of GPS and GNSS receivers that operate in South and Central America and the Caribbean region are used to observe the morphology of the equatorial ionization anomaly (EIA), examine the evolution of plasma bubbles, and investigate the enhancement of L‐band scintillations that occurred on February 12 and 13, 2016. A few weak and short magnetic storms developed these days, and a minor sudden stratospheric warming (SSW) event was initiated a few days before. During these unusual conditions, TEC maps reported a split of the otherwise continuous crests of the EIA and the formation of a large‐scale (thousands of kilometers) almost‐circular structure. The western part of the southern crest faded, and a north‐south aligned segment developed near the center of the South American continent, joining the north and south crests of the EIA, forming an anomaly that resembled a closed loop on the eastern side of the continent. Concurrently with the anomaly events, several GPS stations reported increases in the L‐band scintillation index from 0.4 to values greater than 1. We analyzed TEC values from receivers between ±6° from the magnetic equator to identify and follow TEC depletions associated with plasma bubbles when they reach different stations. Although the magnetic activity was moderate (Kp = 3°), we believe that the anomaly redistribution and the scintillation enhancements are not related to a prompt penetration electric field but to enhancing the semidiurnal lunar tide propitiated by the onset of the minor SSW event. We found that depending on the lunar tide phase cycle, the neutral wind's meridional component can augment sub‐km scale irregularities and enhance L‐band scintillations through the wind gradient instability when U·n < 0 or the action of wind gradients (U) within the bubbles. Our observations imply that the SSW event enables prominent changes in the thermosphere wind system at F‐region altitudes.

Doprinos određivanju jonosferskog kašnjenja GNSS satelitskih signala na teritoriji Republike Srbije

Multi-frequency GNSS satellite signals and their availability enable research in undifferentiated and uncombined models in which a single signal at each frequency is a corresponding independent observation. Such possibilities are reflected by the significant interest in geodetic research as well as in many areas of application of GNSS observation. On the geometric path of the signal between the satellite and the receiver, a significant source of GNSS measurement errors comes from the medium of propagation of electromagnetic waves. Errors attributed to signal propagation are ionospheric and tropospheric signal delay. The mentioned error sources significantly affect the quality of certain pseudorange and, thus, the quality of the receiver's position in the form of three-dimensional coordinates. This paper presents the analysis and determination of the ionospheric delay of GNSS satellite signals based on the determination of Total Electron Content - TEC at five stations (Beograd, Leskovac, Sombor, Zaječar, and Kraljevo) in the territory of the Republic of Serbia. In order to determine TEC values, the software called "GPS-TEC analysis" developed within the Institute for Scientific Research, Boston College, USA was used, which enables the determination of the TEC value on the path between the satellite and the receiver. The data collection was carried out within the year 2022 so that the measurement sessions include characteristic dates when the most significant fluctuations are expected in the context of seasonal variations.

Ionospheric response during Tropical Cyclones - A Brief Review on Amphan and Nisarga

Here, we explore the different characteristics of a possible coupling between tropospheric and ionospheric activities during the impact of tropical cyclones (TC) like Amphan and Nisarga in the Indian subcontinent. We have analyzed the effect of TCs Amphan and Nisarga on the low latitude ionosphere using the measurements from several IGS stations around India and a GPS + NavIC station in Indore, India. For the first time, this study assesses the impact of tropical cyclones on the equatorial ionosphere using both GPS and NavIC. After the landfall of TC Amphan, the VTEC analysis shows a significant drop from nominal values in both NavIC as well in GPS by 5.1 TECU and 3.6 TECU, respectively. In contrast to TC Amphan, Nisarga showed a rise in VTEC which ranged from 0.9 TECU in GPS to 1.7 - 5 TECU in NavIC satellites except for PRN6. The paper examines Outgoing Longwave Radiation as a proxy to the convective activity which may be responsible for the ionospheric variation through the generation of gravity waves. In addition, the horizontal neutral wind observations at the location of TC landfall confirm the presence of ionospheric disturbances. VTEC perturbation analysis using a band-pass filter reveals a variation in differential TEC values between ±0.4 and ±0.8 based on the IGS station measurements. This indicates that the gravity wave is one of the responsible mechanisms for the lower–upper atmospheric coupling during both cyclones.