Paraparesis due to angio-neurotropic Gurltia paralysans in a domestic cat (Felis catus) and retrospective study on feline gurltiosis cases in South America.

Introduction: The nematode Gurltia paralysans is a neglected angio-neurotropic parasite causing chronic meningomyelitis in domestic cats (Felis catus) as well as wild felids of the genus Leopardus in South America. Adult G. paralysans nematodes parasitize the leptomeningeal veins of the subarachnoid space and/or meningeal veins of the spinal cord parenchyma. The geographic range of G. paralysans encompasses rural and peri-urban regions of Chile, Argentina, Uruguay, Colombia and Brazil. Methods: This case report presents clinical and pathological findings of a G. paralysans-infected cat suffering from severe thrombophlebitis and meningomyelitis resulting in ambulatory paraparesis. Neurological examination of affected cat localized the lesions at the thoracolumbar (T3-L3) and lumbosacral (L4-Cd4) segments. Molecular and morphological characteristics of extracted nematodes from parasitized spinal cord veins confirmed G. paralysans. Additionally, data obtained from a questionnaire answered by cat owners of 12 past feline gurltiosis cases (2014-2015) were here analyzed. Questionnaire collected data on age, gender, geographic location, type of food, hunting behavior, type of prey, and other epidemiological features of G. paralysans-infected cats. Results and Discussion: Data revealed that the majority of cats originated from rural settlements thereby showing outdoor life styles with hunting/predatory behaviors, being in close contact to wild life [i.e. gastropods, amphibians, reptiles, rodents, birds, and wild felids (Leopardus guinia)] and with minimal veterinary assistance. Overall, this neglected angio-neurotropic G. paralysans nematode still represents an important etiology of severe thrombophlebitis and meningomyelitis of domestic cats living in endemic rural areas with high biodiversity of definitive hosts (DH), intermediary (IH), and paratenic hosts (PH). The intention of this study is to generate awareness among veterinary surgeons as well as biologists on this neglected feline neuroparasitosis not only affecting domestic cats but also endangered wild felid species of the genus Leopardus within the South American continent.

Sulfur-Doped g-C3N4 Heterojunctions for Efficient Visible Light Degradation of Methylene Blue.

The discharge of synthetic dyes from different industrial sources has become a global issue of concern. Enormous amounts are released into wastewater each year, causing concerns due to the high toxic consequences. Photocatalytic semiconductors appear as a green and sustainable form of remediation. Among them, graphitic carbon nitride (g-C3N4) has been widely studied due to its low cost and ease of fabrication. In this work, the synthesis, characterization, and photocatalytic study over methylene blue of undoped, B/S-doped, and exfoliated heterojunctions of g-C3N4 are presented. The evaluation of the photocatalytic performance showed that exfoliated undoped/S-doped heterojunctions with 25, 50, and 75 mass % of S-doped (g-C3N4) present enhanced activity with an apparent reaction rate constant (kapp) of 1.92 × 10-2 min-1 for the 75% sample. These results are supported by photoluminescence (PL) experiments showing that this heterojunction presents the less probable electron-hole recombination. UV-vis diffuse reflectance and valence band-X-ray photoelectron spectroscopy (VB-XPS) allowed the calculation of the band-gap and the valence band positions, suggesting a band structure diagram describing a type I heterojunction. The photocatalytic activities calculated demonstrate that this property is related to the surface area and porosity of the samples, the semiconductor nature of the g-C3N4 structure, and, in this case, the heterojunction that modifies the band structure. These results are of great importance considering that scarce reports are found concerning exfoliated B/S-doped heterojunctions.

A Technical Note of Improvement of the Elnady Technique for Tissue Preservation in Veterinary Anatomy.

Teaching veterinary anatomy has been subjected to changes and restrictions that have promoted the development of new techniques for preserving organs and cadavers. The Elnady technique is a recent method for the conservation of tissues. Specimens produced with this technique are realistic, durable, soft, and flexible, but an undesirable feature is the discoloration of tissues. In the present study, we describe modifications of the Elnady technique for organ and tissue preservation. Specimens were prepared on the theoretical basis of the Elnady technique, but at low temperatures and with longer durations for the fixation, dehydration, glycerin impregnation and curing processes. Furthermore, the tissues were pigmented with a red vegetable pigment before dehydration or in the glycerin impregnation process. The results show high-quality specimens with minimal shrinkage and natural color aspects. The modified Elnady technique is adequate for producing specimens of better contrast for education purposes.

Understanding the solid-liquid equilibria between paracetamol and activated carbon: Thermodynamic approach of the interactions adsorbent-adsorbate using equilibrium, kinetic and calorimetry data.

In this work, we presented the paracetamol-activated carbon interactions and their effect on the adsorption capacity. We evaluated kinetic, equilibrium, and calorimetric data using different solvents (water, HCl 0.1 M, and NaCl 0.1 M) to evaluate the changes in the adsorbent-adsorbate interaction. In addition, the commercial activated carbon (AC) was modified through thermal (ACTT) and chemical (ACNA) methods to change the physicochemical properties of the adsorbents. The relative kinetic constants decrease with the content of basic groups on the activated carbon, indicating a lower influence of diffusion on the adsorption rate when the chemical interactions increase (0.1 ACNA >0.09 AC >0.03 ACTT mmol g-1). The adsorption capacity for AC at acidic pH increases slightly compared to tests carried out in the water. Under this condition, the adsorbed amount of paracetamol was 1.31 mmol g-1. However, the maximum adsorption capacity was achieved on ACTT using water as solvent (1.57 mmol g-1). The paracetamol adsorbed decreases in NaCl (osmotic, ionic strength) on all activated carbons by around 20%. The interaction enthalpy of the paracetamol-activated carbon interaction presents values between - 18.0 and 2.3 J per molecule adsorbed. The Gibbs energy released during the adsorption process is between - 33.1 and - 29.8 kJ mol-1.

Physicochemical Parameters of the Methylparaben Adsorption from Aqueous Solution Onto Activated Carbon and Their Relationship with the Surface Chemistry.

The methylparaben adsorption from aqueous solution onto activated carbon is a relevant topic because of the toxicity of this compound for human and environmental health. The physicochemical parameters allow us to evaluate the performance of the adsorption and the relationship between the surface chemistry and the adsorbed amount of methylparaben. The effect of the solution chemistry on the adsorption was also evaluated. In this work, the methylparaben adsorption on three activated carbons with different physicochemical properties, specifically different contents of oxygenated groups and total basicity, is presented. Kinetic, equilibrium, and calorimetry tests were conducted. The maximum adsorbed amount of methylparaben was achieved on an activated carbon with basic characteristics, Q max = 1.64 mmol g-1; in the same activated carbon, the initial rate was 0.20 mmol g-1 h-1, and the value determined for the interaction enthalpy was -12.6 × 10-20 J molecules-1, and the Gibbs energy change was close to -14.96 kJ mol-1.

Adsorption of Pharmaceutical Aromatic Pollutants on Heat-Treated Activated Carbons: Effect of Carbonaceous Structure and the Adsorbent-Adsorbate Interactions.

Drugs are considered emerging pollutants from water sources and are therefore considered to be of high toxicological risk to aquatic fauna. Activated carbon adsorption is one of the methods approved by the Word Health Organization to remove pharmaceutical compounds from water in treatment plants due to its cost and easy implementation. This study presents the modification of a commercial activated carbon by heat treatment at 1073, 1173, and 1273 K. The impact of the physicochemical changes of the adsorbent on the adsorption capacity of salicylic acid and methylparaben, compounds derived from phenol, was studied. Finally, the adsorbate-adsorbent interactions are evaluated through immersion calorimetry. It is observed that at 1173 K, activated carbon increases its surface area by 29%. At higher temperatures, the surface area drops to 21%. In the activated carbon subjected to heat treatment at 1173 K, it increases the adsorption capacity of salicylic acid and methylparaben by 24 and 34%, respectively, compared to activated carbons subjected to higher temperatures. The interaction enthalpies (adsorbate-adsorbent interaction) have values between -12 and 5 J g-1.

A new methodology to determine the effect of the adsorbate-adsorbent interactions on the analgesic adsorption onto activated carbon using kinetic and calorimetry data.

This work proposes a new methodology to determine the adsorption mechanism for salicylic acid and paracetamol on activated carbon based on the physicochemical characteristics of adsorbent and adsorbates. The methodology is divided into two parts: the determination of adsorption kinetics (order and mechanism) and the study of the chemical interactions (adsorbate-adsorbent and solvent-adsorbent) using calorimetry tests. Then, the results obtained in both techniques were correlated with the amount of drug adsorbed. The adsorption kinetics of salicylic acid and paracetamol on activated carbons with different oxygen contents could be described with widely kinetic models such as intraparticle, pseudo-first-order, pseudo-second-order, Avrami, and Elovich models; different information about the adsorption mechanism are offered by each of them. The results indicated that the pseudo-first-order rate constant decreases with the molecular size of analgesics and the carboxylic acid groups on the adsorbent surface; the rate constant values are between 0.12 and 2.31 h-1. The adsorbed amount of analgesics and the adsorption rate are greatest on activated carbons with basic characteristics (QRAC 0.45 > 0.24 > 0.21 mmol g-1 for phenol, salicylic acid, and paracetamol, respectively). The enthalpy changes follow the same trend in all activated carbons; for RAC, the results were ΔHimmPHEN = - 33.4 J g-1, ΔHimmSA = - 35.9 J g-1, and ΔHimmPAR = - 45.4 J g-1. The analgesic diffusion rate in the boundary layer increases with the formation of adsorbate-adsorbent interactions (exothermic process).

Mechanisms of Methylparaben Adsorption onto Activated Carbons: Removal Tests Supported by a Calorimetric Study of the Adsorbent⁻Adsorbate Interactions.

: In this study, the mechanisms of methylparaben adsorption onto activated carbon (AC) are elucidated starting from equilibrium and thermodynamic data. Adsorption tests are carried out on three ACs with different surface chemistry, in different pH and ionic strength aqueous solutions. Experimental results show that the methylparaben adsorption capacity is slightly affected by pH changes, while it is significantly reduced in the presence of high ionic strength. In particular, methylparaben adsorption is directly dependent on the micropore volume of the ACs and the π- stacking interactions, the latter representing the main interaction mechanism of methylparaben adsorption from liquid phase. The equilibrium adsorption data are complemented with novel calorimetric data that allow calculation of the enthalpy change associated with the interactions between solvent-adsorbent, adsorbent-adsorbate and the contribution of the ester functional group (in the methylparaben structure) to the adsorbate⁻adsorbent interactions, in different pH and ionic strength conditions. It was determined that the interaction enthalpy of methylparaben-AC in water increases (absolute value) slightly with the basicity of the activated carbons, due to the formation of interactions with π- electrons and basic functional groups of ACs. The contribution of the ester group to the adsorbate-adsorbent interactions occurs only in the presence of phenol groups on AC by the formation of Brønsted⁻Lowry acid⁻base interactions.

Adsorción de acetaminofén sobre carbones activados a diferente pH. Entalpía y entropía del proceso / Acetaminophen adsorption on activated carbons at different pH. Change of enthalpy and entropy of the process / Adsorção de acetaminofeno em carvões ativados a diferentes pH. Entalpia e entropia do processo

Resumen Se analizaron los cambios entálpicos y entrópicos derivados del proceso de adsorción de acetaminofén sobre carbones activados con química superficial modificada. Se realizó, además, una variación del pH para determinar los cambios en las propiedades termodinámicas cuando existen cargas en el adsorbato y en el adsorbente. Se encontró que la máxima capacidad de adsorción (1,172 mmoles g-1) corresponde al proceso llevado a cabo en el carbón activado denominado CAR en este estudio a pH 7; los valores de las funciones termodinámicas de entalpía de inmersión y entropía de adsorción fueron -36,02 J g-1 y 0,123 J g-1 K-1, respectivamente. Así, el cambio de entropía de adsorción para el acetaminofén en los carbones activados estudiados dependió del pH. Se encontró que esta función termodinámica varía en el siguiente orden pH 2 > pH 11 > pH 7. Este comportamiento se relaciona con el número de especies presentes en la solución capaces de interactuar con la superficie del carbón activado.

Abstract The enthalpic and entropic changes resulting from the process of acetaminophen adsorption on activated carbons with modified surface chemistry were studied. A pH variation was performed to determine the changes in the thermodynamic properties when there are charges in the adsorbate and adsorbent. It was found that the maximum adsorption capacity (1.172 mmoles g-1) corresponds to the process carried out in the activated charcoal labeled as CAR in this study at pH 7; the values of the thermodynamic functions immersion enthalpy and entropy of adsorption were -36.02 J g-1 and 0.123 J g-1 K-1, respectively. Thus, the adsorption entropy change for the acetaminophen on the activated carbons depended on the pH. It was found that this thermodynamic function varies in the following order pH 2 > pH 11 > pH 7. This behavior is related to the number of species present in the solution capable of interact with the activated carbon surface.

Resumo Foram analisadas as mudanças entrópicas e entalpicas resultantes do processo de adsorção de acetaminofeno sobre carvões activados com superfície química modificada. Além disso, foi realizada uma variação do pH para determinar as alterações nas propriedades termodinâmicas quando existem cargas no adsorbato e no adsorvente. Foi encontrado que a máxima capacidade de adsorção (1.172 mmol g-1) corresponde ao processo realizado no carvão ativado chamado CAR neste estudo em pH 7; os valores das funções termodinâmicas de entalpia de imersão e entropia de adsorção foram -36,02 J g-1 e 0,123 J g-1 K-1 respectivamente. As mudança da entropia de adsorção para o acetaminofeno nos carvões activados dependeu do pH. Foi encontrado que esta função termodinâmica varia na seguinte ordem pH 2 > pH 11 > pH 7. Este comportamento está relacionado ao número de espécies presentes na solução capaz de interagir com a superfície de carvão activado.

Effect of Solution pH on the Adsorption of Paracetamol on Chemically Modified Activated Carbons.

Paracetamol adsorption in acidic, neutral and basic media on three activated carbons with different chemistry surfaces was studied. A granular activated carbon (GAC) was prepared from coconut shell; starting from this sample, an oxidized activated carbon (GACo) was obtained by treating the GAC with a boiling solution of 6 M nitric acid, so to generate a greater number of oxygenated surface groups. In addition, a reduced activated carbon (GACr) was obtained by heating the GAC at 1173 K, to remove the oxygenated surface groups. Paracetamol adsorption was higher for GACr due to the lower presence of oxygenated surface functional groups. Moreover, adsorption was highest at neutral pH. The magnitude of the interactions between paracetamol molecules and activated carbons was studied by measuring the immersion enthalpies of activated carbons in solution of paracetamol at different concentrations and pH values and by calculating the interaction enthalpy. The highest value was obtained for GACr in a paracetamol solution of 1000 mg L-1 at pH 7, confirming that paracetamol adsorption is favoured on basic activated carbons at pH values near to neutrality. Finally, the Gibbs energy changes confirmed the latter result, allowing explaining the different magnitudes of the interactions between paracetamol and activated carbons, as a function of solution pH.

Comparative calorimetry study of the phenol and acetaminophen adsorption on activated carbon in aqueous solution / Estudio calorimétrico comparativo de la adsorción sobre carbón activado de fenol y acetaminofén desde solución acuosa

Immersion enthalpies were determined for aqueous solutions of phenol, acetaminophen and water on three different carbons that differed in terms of oxygen groups on the surface. The intensity of the energy interaction between these compounds and the activated carbons was determined. The activated carbons had similar values for surface area and micropore volume, i.e. approximately 850 m².g-1 and 0.35 cm³.g-1, respectively, but differed in the content of surface chemical groups that interacted with the solutes in aqueous solution. The values obtained for the enthalpies of immersion of activated carbon in water were between -32 and -66 J.g-1. The enthalpies of immersion of activated carbon for acetaminophen and phenol solutions with concentrations between 100 mg.L-1 and 10 mg.L-1 were between -18 and -157 J.g-1, indicating greater interaction between the two solutes and activated carbons with a high surface content of reduced chemical groups.

Se determinan las entalpías de inmersión en soluciones acuosas de fenol y acetaminofén y en agua de tres carbones activados que difieren en el contenido de grupos oxigenados superficiales con el propósito de conocer la intensidad de las interacciones energéticas entre los compuestos y los carbones activados. Los carbones activados presentan valores de área superficial y volúmenes de microporo similares, alrededor de 850 m².g-1 y 0,35 cm³.g-1, respectivamente, y difieren en el contenido de grupos químicos superficiales que son los que interactúan con los solutos que se encuentran en solución acuosa. Los valores obtenidos para las entalpías de inmersión de los carbones activados en agua están entre -32 y -66 J.g-1. Las entalpías de inmersión de los carbones activados en las soluciones de 100 mg.L-1 y 10 mg.mL-1 de fenol y acetaminofén se encuentran entre -18 y -157 J.g-1, que indican una mayor interacción para los dos solutos con el carbón activado que tiene mayor contenido de grupos básicos superficiales.