Effects of (Li-Na)2CO3 on The Electrical Properties of Calcia-Stabilized Zirconia/Carbonate Composite Electrolytes

Calcia-Stabilized Zirconia (CSZ) is potential as low-cost electrolytes material for Solid oxide fuel cell (SOFC). It is fluorite structure widely known as oxygen ion conductors. Addition of carbonate salt into fluorite-based electrolyte is common to overcome low conductivity of CSZ as well as to decrease sintering temperature. Increase of ionic conductivity in the SOFC electrolyte is also influenced by presence of protons (H+), so it is called mixed-ion electrolytes. In this study, the effect of sintering temperature and carbonate content prepared from mixture of Li2CO3 and Na2CO3 on the relative density, ionic conductivity and microstructure of electrolyte and fuel cell performance was investigated. The sintered CSZ/carbonate samples were examined physically and electrochemically by using SEM, TEM, XRD, and EIS. The unique detail of nanostructure for CSZ/carbonate was investigated by TEM. The XRD is to observed peak associating with CSZ, Li2CO3, and Na2CO3, as well as its crystallinity. Moreover, the electrolyte resistance was measured by EIS so that the proton conductivity and oxygen conductivity of CSZ/carbonate can be calculated. The improvement of low-cost electrolyte material such as CSZ can be realized by providing protons pathway.

Impact of Plasma-Activated Water (PAW) on Seed Germination of Soybean

The present study reports the generation of plasma-activated water (PAW) using dielectric barrier discharge (DBD), its physicochemical properties, and its potential impact on the seed germination and seedling growth of soybean. The results revealed significant changes in physical parameters, such as pH, total dissolved solids, total suspended solids, turbidity, conductivity, dissolved oxygen, and chemical parameters, such as calcium, chromium, sodium, manganese, nitrate, nitrites, phosphorus, and sulfur and biological parameter such as E. coli in water after plasma treatment. The concentration of dissolved oxygen, conductivity, nitrate, nitrite, and sulfur was increased with an increase in water treatment time, and the amounts of the other analyzed parameters decreased with the increase in water treatment time. The effects of untreated water and plasma-activated water treated for 20 minutes on soybean germination and growth were studied. The germination rate was found to be higher with plasma-treated water. Shoot lengths, seedlings length, vigor index, and germination rates were increased as compared to those germinated by normal water irrigation. The seedlings irrigated with PAW responded to the abundance of nitrogen by producing intensely green leaves because of their increased chlorophyll a as compared to seedlings irrigated with normal water. However, the content of chlorophyll b and carotenoids was found to decrease in the case of seedlings irrigated with PAW. Based on this report, we conclude that PAW could be used to substantially enhance seed germination and seedling growth.

Artificial floating islands as a tool for the water quality improvement of fishponds

In this study, the ecotechnology artificial floating islands (AFIs), colonized by Eichhornia crassipes, have been tested as a tool for water quality improvement of fishponds. The experiment was carried out in semi-intensive production during the grow-out period of Nile tilapia, comprising one production cycle. It was completely randomized with two treatments (with and without AFIs) and three replications. Temperature, dissolved oxygen, conductivity, pH, turbidity, total dissolved solids (TDS), transparency (Secchi) and concentrations of chlorophyll a (CL a), total nitrogen (TN), total ammonia nitrogen (TAN), total phosphorus (TP) and orthophosphate (PO43--P) were analyzed fortnightly in the fishponds. Two groups ordered based on environmental characteristics were formed by applying the Principal Component Analysis (70.68% of explicability). The fishponds with AFIs were assigned to higher values of Secchi and lower values of pH, turbidity, TDS and concentrations of nutrients. On the other hand, the fishponds without AFIs were assigned to the highest values of these variables, except for Secchi. In 30 days, the AFIs showed the lowest concentrations of TP and PO43--P, and for CL a, TN and TAN, the differences were recorded after 90 days. The use of AFIs has demonstrated potential to conserve water quality in fishponds, notably for biologically assimilable elements (PO43--P and TAN) and for those directly related to eutrophication (P and N). Artificial floating islands should be encouraged for small and medium-sized farmers as tool to improve water quality in fishponds. However, new AFIs coverage rates must be evaluated, as well as the control of hydraulic retention rates. Keywords: aquaculture, ecotechnology, free-floating aquatic macrophytes.

Abundance and Diversity of Snails in Relation to Physicochemical Parameters along Kwadom Stream, Gombe State, Nigeria

Aims: The aim of the study is to investigate the abundance and diversity of snails along Kwadom stream, Gombe state, Nigeria. Study Design: Snails were collected using a benthic scoop net with mesh size of 0.2 mm and hand picking from three sampling stations (home, farmlands, and fishponds sites) along Kwadom stream; between 6:30 am to 11:00 am weekly. In addition, physicochemical parameters (temperature, dissolved oxygen, conductivity, alkalinity, water depth and pH) were measured fortnightly to determine their effect on the diversity of snail species. Place and Duration of Study: The study was conducted along Kwadom stream in Yamaltu Deba Local Government Area of Gombe State, Nigeria from March to July 2021. Methodology: Snails were collected from each of the three stations and identified to species level using hand lens and taxonomy keys. Water physicochemical parameters: temperature, dissolved oxygen, conductivity, alkalinity, water depth and pH were measured using standard method. General linear models (GLM) were used to compare the abundance and diversity of the snails across the sampling station, as well as the effect of physicochemical parameters on the diversity of snails. Results: 160 individual snails were recorded from 11 species, including Biomphalaria pfeifferi– the intermediate host of Schistosoma mansoni. The result showed there was a significant difference in the abundance of snails (p<0.01) across the three study sites – home site 68 (42.5%), farmlands site 56 (35%) and fishpond site 36 (22.5%). The home site had a higher diversity of snail species (p<0.01) relative to the farmlands and fishponds sites. Temperature, conductivity, and alkalinity had a significant effect on the diversity of snails. Conclusion: Overall, Kwadom stream harbors many individual snail species, suggesting the need for educating the public on the mode of transmission of diseases that are caused by these snails.

Abundance and annual distribution of freshwater snails and some trematode cercariae at Damietta Governorate, Egypt

Summary In addition to being a good food source, freshwater snails are considered one of the positively and negatively influencing invertebrates on the environment. Several biotic and abiotic factors are thought to affect the distribution and the dynamics of these snails. Freshwater snails are the most dominant and conspicuous individuals of the freshwater biota in Damietta Governorate. In this study, freshwater snails were collected monthly from 5 geographically and environmentally different sites at Damietta Governorate at the north of Egypt during June 2017-May 2018. Seven snail species; Lanistes carinatus, Lanistes varicus, Pila wernei, Segmentorbis angustus, Melanoides tuberculata, Biomphalaria alexandrina, and Gabbiella senoriansis, were identified. Lanistes carinatus was the most abundant species (56.4%) in the collection sites. Besides, Al-Inaniyyah village had the highest snail species abundance and variety. The abundance of the most recorded species varied seasonally; the highest abundance was recorded during summer while the lowest was during winter. The abundance of some snail species correlated positively or negatively with some physico-chemical parameters; water temperature, dissolved oxygen, conductivity, total dissolved salts, and electrical conductivity. Two types of trematode cercariae; gymnocephalus cercariae and xiphidiocercariae, were harvested from Lanistes carinatus. The highest prevalence of both cercarial types was detected during summer. The correlation between the prevalence of both cercarial types and the physico-chemical parameters were determined. Xiphidiocercariae were the most predominant cercarial type in Damietta Governorate. Our findings suggest that the invasion of some freshwater snails is likely to be the cause of the low prevalence or complete absence of some medically important intermediate snail hosts. We recommend further characterization of the distribution of freshwater snails and the interrelationships among them in Egypt, and suggest a controlled use of selected snail species to combat their medically important analogues.

Zirconium dioxide. Review

A review of zirconium dioxide or zirconia ZrO2 is presented. The finding of zirconium compounds in nature, the physical and chemical properties of ZrO2 are given, the polymorphism of zirconium oxide, and the phase diagrams of systems with its participation are considered. The areas of application of zirconia compounds are highlighted: automotive industry, electronics industry, energy and industrial ecology, equipment manufacturing and mechanical engineering the production of zirconium-based refractories, ceramics, enamels, glass, superhard materials, applications in medicine, nuclear energetics, and many others areas of human activity. Cubic modification of zirconium dioxide, stabilized by oxides of rare earth elements,is a jewelry stone (fianite). Partially stabilized zirconium dioxide is a versatile structural material with very high resistance to crack propagation. Solid solutions of REE oxides, especially scandium, have a high oxygen conductivity, which is used in sensors for measuring the partial pressure of oxygen and in fuel cells. Attention is paid to heat-resistant oxide ceramic materials with low thermal conductivity used in the quality of heat-resistant coatings. Considerable attention was paid to the second most important mineral of zirconia - baddeleyite (ZrO2). Baddeleyite is widely used in the production of refractory materials. It is mined for the production of metallic zirconium. The achievements of Soviet and Russian scientists in thedevelopment of technologies for the production of fianite and artificial baddeleyite are presented.

Effect of the Reactant Transportation on Performance of a Planar Solid Oxide Fuel Cell

The process of reactant transportation greatly affects the performance of solid oxide fuel cells (SOFCs). Therefore, a three-dimension numerical SOFC model was built to evaluate mainly the effect of the reactant transportation coupling of heat and mass transfer and electrochemical reactions, and the reliability of numerical calculations was validated. Numerical studies revealed the correlation of both increase of reactant concentration gradients and improved mass transfer capability of multi reactants in gas diffusion electrode with the enhancement of the SOFC performance, in the condition of enough supplies of the fuel and the oxidant. Further studies identified the oxygen ions conductivity in electrolytes played a critical role in energy output and thus the performance of SOFCs. For example, the current density would increase by 65% if the ionic conductivity of electrolytes doubled. This study gives insight into the significance of operational conditions, electrolytes, and structures on the ionic oxygen conductivity and further on the optimization of the SOFCs. Overall, the numerical modeling leads a clear path toward the optimization of SOFCs.

Are chironomidae (diptera) good indicators of impact in lotic environments?

Chironomid larvae are widely distributed, with high diversity and abundance, and exploit a range of habitats and food resources. They are also an important food resource for various groups of aquatic organisms. Therefore, this study aimed to evaluate the spatial and seasonal variations in the composition of diet and genera of Chironomidae larvae in two streams located in south central west region of Brazil, associated with the environmental impact assessment, based on visual, physical and chemical indicators of streams. The contents of the digestive tracts of the most abundant genera were observed and classified into fine detritus, coarse detritus, algae, fungi, or animal material. Dissolved oxygen, conductivity, and incident light, along with the dominance of certain genera, were strong indicators of pollution in the impacted stream. Cluster analysis indicated three trophic groups: 1) generalist detritivores, consuming fine particulate organic matter and making up 82 % of the genera analyzed; 2) predators, which consumed mainly animal material; and 3) specialist shredding detritivores, present only in the less-impacted stream. These results are useful in understanding anthropogenic effects on stream ecosystems.

Calculation of Carbon-Titanium-Oxygen Conductivity by First Principle

It is the hot point of the present study to obtain the metal titanium by using the carbon-titanium-oxygen electrolysis. The electrical conductivity, melting point and hardness of C-Ti-O have great influence on the feasibility of electrolysis process. In this paper, the conductivity of rutile titanium dioxide, carbon replacement solid solution (20%, 50%, 80%) and titanium carbide are calculated by first principles. It was found that the more carbon substituted rutile titanium dioxide, the better its conductivity. The electrical conductivity of objects are changed from semiconductors to good conductors. The experimental results show that the conductivity of the experimental results is higher than that of the calculated ones, which may be due to the existence of a large number of hole-excited elements.

Composition, crystallography, and oxygen vacancy ordering impacts on the oxygen ion conductivity of lanthanum strontium ferrite

The oxygen conductivity map for LSF illustrates the impact of aliovalent doping, crystal structure, and oxygen vacancy interactions on conductivity.