Paraffin-Peloid Formulations from Copahue: Processing, Characterization, and Application.

The Copahue Thermal Center, situated in Neuquén, Argentina, produces natural and matured peloids, which are employed in the prevention and treatment of various osteoarticular and dermatological disorders. The presence of sulfur as a constituent and its thermotherapeutic potential constitute the primary strengths of these peloids. Nevertheless, accessing Copahue is challenging due to its distance from densely populated centers and the snow cover during the winter months in the southern hemisphere. Therefore, in order to propose a material that can be utilized year-round in any location, a mudpack was obtained by combining medicinal paraffin with dehydrated Copahue peloids, with concentrations evaluated up to 10% w/w. This mudpack was analyzed through X-ray diffraction, which detected the presence of sulfur, the most important component of Copahue's peloids. Through IR spectroscopy, the signals that identify medicinal paraffin were clearly observed, and for concentrations of 6% and 10% peloid in the material, it was possible to detect the presence of mineral clay components associated with Si-O stretching vibrations at around 1041 cm-1. The low values of luminosity and grey tonality obtained for the mudpack contributed to patient acceptability and the absorption of electromagnetic radiation. The experimental cooling rate, calculated using the ratio of the temperature variation (∆T) with respect to the time variation (∆t) in each interval of the experimental curve, was determined to be 0.6 °C·min-1 for both paraffin and the mudpack. However, for peloids, higher values ranging from 0.6 to 4.8 °C·min-1 were obtained. This suggests that the mudpack mixtures have a slower heat release, which is a desirable property for their use as a thermotherapeutic agent. Considering the reusability of the mudpack, its stability was evaluated after 10 cycles of cooling and heating through XRD, DSC, and FTIR tests, resulting in a system that retains its properties. The formulation of the obtained mudpack is promising for the development of these materials on a larger scale.

A Preliminary Study of SARS-CoV-2's Permanence and Potential Infective Capacity in Mineromedicinal Waters of Copahue, Neuquén, Argentina.

Copahue Thermal Center is characterized by the presence of mineromedicinal acidic waters with high temperatures, therapeutic peloids, and relevant consortia of extremophiles species, distributed in small natural pools which cannot be disinfected. The objective of this research was to investigate the survival of SARS-CoV-2 in Copahue's waters and its remaining infective capacity. In a first assay, a decrease of more than 50% of the initially viral load compared to the initially inoculated positive sample was detected for all the water samples analyzed. After that, two of the Copahue springs, which are used as an immersion bath in closed environments without going through any disinfection treatment, was selected to determine the viral viability. VERO cell infections were performed, with no cytopathic effect detected, but a strikingly high resistance of the virus, detecting its genome by real time PCR, during the seven days of study under laboratory conditions. SARS-CoV-2 survival in acid media was reaffirmed, which is a peculiarity for a covered virus. A decrease in the detectable viral load of the positive sample was found as the infection time passed, becoming completely negative in the subsequent blind passages. More research is needed to further study the feasibility of SARS-CoV-2 in mineromedicinal waters, especially natural acidic waters that cannot disinfected, in order to expand information about the risk to populations that are exposed to them.

Removal of Ciprofloxacin from Aqueous Solutions Using Pillared Clays.

Emerging contaminants in the environment have caused enormous concern in the last few decades, and among them, antibiotics have received special attention. On the other hand, adsorption has shown to be a useful, low-cost, and eco-friendly method for the removal of this type of contaminants from water. This work is focused on the study of ciprofloxacin (CPX) removal from water by adsorption on pillared clays (PILC) under basic pH conditions, where CPX is in its anionic form (CPX-). Four different materials were synthetized, characterized, and studied as adsorbents of CPX (Al-, Fe-, Si-, and Zr-PILC). The highest CPX adsorption capacities of 100.6 and 122.1 mg g-1 were obtained for the Si- and Fe-PILC (respectively), and can be related to the porous structure of the PILCs. The suggested adsorption mechanism involves inner-sphere complexes formation as well as van der Waals interactions between CPX- and the available adsorption sites on the PILC surfaces.

Influence of Ca2+ on tetracycline adsorption on montmorillonite.

The adsorption of tetracycline (TC) on montmorillonite was studied as a function of pH and Ca(2+) concentration using a batch technique complemented with X-ray diffraction and transmission electron microscopy. In the absence of Ca(2+), TC adsorption was high at low pH and decreased as the pH increased. In the presence of Ca(2+), at least two different adsorption processes took place in the studied systems, i.e., cation exchange and Ca-bridging. Cation exchange was the prevailing process at pH<5, and thus, TC adsorption decreased by increasing total Ca(2+) concentration. On the contrary, Ca-bridging was the prevailing process at pH>5, and thus, TC adsorption increased by increasing Ca(2+) concentration. The pH 5 represents an isoadsorption pH where both adsorption processes compensate each other. TC adsorption became independent of Ca(2+) concentration at this pH. For TC adsorption on Ca(2+)-montmorillonite in 0.01 M NaCl experiments, the ratio adsorbed TC/retained Ca(2+) was close to 1 in the pH range of 5-9, indicating an important participation of Ca(2+) in the binding of TC to montmorillonite. X-ray diffraction and transmission electron microscopy showed that TC adsorption induced intercalation between montmorillonite layers forming a multiphase system with stacking of layers with and without intercalated TC.

Solution and solid state properties of a set of procaine and procainamide derivatives.

A set of potential Class III antiarrhythmic agents of structure p-HOOC-R-CO-NH-C(6)H(4)-CO-X-C(2)H(5)-N(C(2)H(5))(2) were isolated as crystalline solids of the amide and ester derivatives, I: succinylprocainamide (X=-NH-, R=-C(2)H(4)-); II: succinylprocaine (X=-O-, R=-C(2)H(4)-); III: maleylprocainamide (X=-NH-, R=-C(2)H(2)-) and IV: maleylprocaine (X=-O-, R=-C(2)H(2)-). Although compounds I-IV exhibit similar solution properties (i.e. acid-base speciation, with zwitterionic (+-) to neutral (00) form ratios higher than 10(4)), aqueous solubility of -NH- derivatives is significantly higher than that of -O- derivatives and also, solvent effects on solubility (i.e. the change of water by ethanol) is clearly different in both series. Solution and solid-state properties of I-IV were characterized to account for the observed differences. Results indicate that procainamide derivatives I and III crystallizes as (+-)(s) but procaine derivatives II and IV as (00)(s). Besides, I is anhydrous but II-IV are hydrates. Aqueous solubility and solvent effect on solubility are controlled by the intrinsic solubility of the species (+-) in I and III and (00) in II and IV. The rise of hydrophilicity of species (00) due to the structural change from -O- to -NH- would determine the change in the structure of the precipitating crystals from (00)(s) to (+-)(s). Solid structure (zwitterionic or neutral), as well as composition (anhydrous or hydrated) may be recognized as the main factors in determining the rank of aqueous solubility of the set: (+-)>(+-.H(2)O)>(00.H(2)O).