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In this current research endeavor, a comprehensive exploration into the properties of ceramic coatings has been undertaken, utilizing bauxite, talc, and kaolin clay. The primary focus lies in the meticulous analysis of the mechanical strength of ceramic proppants. The proppant raw material employed is kaolin clay, treated through a dry coating technique and subsequently sintered at 1300°C. Evaluation of sample performance is based on the establishment of coating and substrate shrinkage. Shrinkage and density assessments are separately conducted for the coating mixtures and substrate. X-ray diffraction (XRD) is employed to discern the crystalline phases within the coatings, while structural characterization is facilitated through scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX). Density and mechanical strength of proppants are meticulously investigated using picnometry and crush tests. The performances of the coated and uncoated samples were compared and investigated. Interestingly, the coated proppants demonstrate slightly higher density than their uncoated counterparts. Remarkably, the specimen featuring a coating composition of bauxite (72wt%)+clay (25wt%)+talc (3wt%) yields optimal results for mechanical strength. The sole crystalline phase detected in the coating is mullite, with a minimum coating thickness of 10μm.

From 58 species collected in the Uruguay river and some of its affluents, new localities are reported for six Characoidei species (Schizodon platae, Glandulocauda terofali, Holoshestes pequira, Hyphessobrycon luetkeni, H. meridionalis and Aphyocharax rubropinnis) and for three Siluriformes (Megalodoras laevigatulus, Auchenipterus nuchalis and Bunocephalus ihe-ringi). For these nine species morphological data and complete Argentine references are given. Chemical data on the affluents are checked with those from neighbouring areas.

The ichthyofauna from subtropical (East) and tropical (West) areas in the Formosa province (Northern Argentina) is analyzed. An up-to-date list of fishes is provided, including 18 new reports for environments associated with the Pilcomayo and Paraguay rivers, considering the detailed distribution of the fishes. Dominant families in terms of number of species are Characidae, Pimelodidae, Loricariidae and Curimatidae. Percentage of individuals (about 5000 examined) were 66% for characoids and 25% for siluriforms, with less than 10% for other groups. Comparisons were made with other South American environments. Most frequent species were Psellogrammus kennedyi, Astyanax bimaculatus, Gymnocorymbus ternetzi, Hoplosternum thoracatum and Cichlasoma portalegrense. The predominant type of environment sampled, of small size and shallow depth, with extensive plant cover, and temporal level variations, explains the dominance of the above groups. This interpretation is supported by independent studies. Diversity values ranged between 0.71 and 3.92. A marked reduction in number of species from East to West was observed (79 and 41 species respectively, 31 shared). No species of Gymnotidae, Hemiodidae, Characidiidae, Trichomycteridae, Lebiasinidae nor Aspredinidae were captured in the West. The higher number of species in eastern environments is considered to be due to the influence of the Paraguay river and the complex hydrology of the area. Other factors, both historical and ecological are considered. A correlation between total phosphorous content in the water and fish richness is also suggested. Water chemistry is compared with near by environments. Sites studied showed pH values from 6.14 to 7.5. The dissolved solid contents ranged from 51.8 to 474.3 mg 1-1, within the hypohaline level. Ionic composition differed somewhat between East and West, water in the East being mainly hypocalcic, as in the Paraguay river. Conductivity was rather variable and Secchi disk values similar to those in the Parana river.

The ichthyology of Santiago del Estero province, a neglected area in Central Argentina is evaluated through the study of samples from 13 localities in the Salado and Dulce rivers basins. Previous information indicates 21 fish species from the Dulce river. Ten new references are added for the province; 6 new ones for the Dulce river, and 15 that represent the first set of species ever reported for the Salado river. Chemical and physical parameters from four spots were obtained, the Dulce and Salado rivers differing in several aspects. The midcourse of Salado river is more similar to the lower than expected, suggesting an influence of the basin characteristics stronger than that of the affluents in the lower course.