RESUMEN

Ethanol (EtOH) 70% is commonly used in collections to preserve and store many unprepared soft-bodied Chalcidoidea. Specimens air-dried directly from alcohol, however, often suffer from collapse of some body parts, making subsequent observation of their morphology difficult or even impossible. We propose an inexpensive method for processing and dry-mounting specimens of Chalcidoidea, using a chemical process including amyl acetate. Four treatments using amyl acetate at different concentrations and exposure times were evaluated for specimens of Eulophidae, Mymaridae, Encyrtidae, Aphelinidae, Pteromalidae, and Trichogrammatidae. Treatment with amyl acetate resulted in specimens of consistently higher quality. Based on our results, treatment of specimens for 1 h with 50:50 amyl acetate and ethanol mixture, followed by treatment for 1 h with 100% amyl acetate, yielded specimens adequate for morphological observations for most of the families. Further experiments are required, however, to optimize this approach for Trichogrammatidae and Eulophidae. This method is a relatively simple, inexpensive, and safe alternative to other methods commonly used for restoring Chalcidoidea preserved in alcohol.

Asunto(s)

RESUMEN

Introducción: Pese a que el uso de corticoides transtimpánicos en pacientes con enfermedad de Méniere es habitual en muchos centros, la evidencia respecto de su efecto sobre los umbrales auditivos es aún controversial. Objetivo: Estudiar los umbrales auditivos de pacientes con enfermedad de Méniere que recibieron corticoides transtimpánicos en el Servicio de Otorrinolaringología del Hospital Clínico de la Universidad de Chile. Material y Método: Estudio retrospectivo de pacientes con enfermedad de Méniere que consultaron entre los años 2015 y 2021. Se estudiaron los umbrales auditivos, antes y después de 3 inyecciones de dexametasona transtimpánica. Resultados: Se obtuvieron datos completos de 27 pacientes. Al comparar el promedio tonal puro antes y después del tratamiento, no se observaron diferencias significativas. A nivel individual, la variación de cambio de los umbrales auditivos con dexametasona se correlaciona en forma significativa con los umbrales auditivos previos a las inyecciones y con el tiempo transcurrido desde la última inyección, pero no con la edad. Conclusión: La terapia con dexametasona transtimpánica en pacientes con enfermedad de Méniere no altera los umbrales auditivos. Sin embargo, se requieren más estudios, para comprobar, si existe un efecto transitorio en los umbrales auditivos de los primeros días posterior al procedimiento.

Introduction: Although transtympanic corticosteroids are proposed in Méniere's disease patients refractory to standard medical therapy, the evidence regarding the effect of transtympanic corticosteroids on hearing thresholds is still controversial. Aim: To study the hearing thresholds of patients with Méniere's disease who were administrated with transtympanic corticosteroids at the Otorhinolaryngology Service of the University of Chile's Clinical Hospital. Material and Method: Retrospective study of Méniere's disease patients who consulted between 2015 and 2021. Demographic variables and hearing thresholds were studied before and after three transtympanic injections of dexamethasone. Results: A total of 27 patients were studied. There were non-significant differences in pure-tone hearing threshold averages before and after the injections. Individual variation in hearing thresholds correlates significantly with the pre-injection hearing thresholds and the period since the last injection, but not with age. Conclusion: Transtympanic dexamethasone therapy in patients with Meniere's disease does not alter hearing thresholds. However, more studies are needed to verify whether there is a transitory effect on hearing thresholds in the first days after the procedure.

Asunto(s)

RESUMEN

Melioidosis is an endemic disease in Southeast Asia and Oceania caused by the gram-negative bacillus Burkholderia pseudomallei. We studied 15 adult patients from Colombia with microbiologically diagnosed pulmonary melioidosis. We reviewed 15 chest X-rays and 10 chest computed tomography (CT) studies. Of the 15 patients, 87% met the criteria for acute infection and 13% met the criteria for chronic infection. The most common findings on chest X-rays were consolidation (86%), nodules (26%), and cavitation (20%). On CT studies, consolidation and nodules were observed in 90% of cases; the areas of consolidation were predominantly located in the basal and central zones in 60%. Areas of cavitation were observed in 50%, pleural effusion in 60%, and mediastinal lymph nodes in 30%. In patients with acute pulmonary melioidosis (n=8), the findings observed were nodules (100%), mixed pattern with nodules and consolidation (87%), pleural effusion (88%), and mediastinal lymph nodes (25%). The two patients with chronic pulmonary melioidosis both had cavitation. Acute lung infection with B. Pseudomallei has radiologic manifestations similar to those of pneumonia due to other causes. In areas where the disease is endemic, it is essential to include acute melioidosis in the differential diagnosis of pulmonary nodules and chronic melioidosis in the differential diagnosis of cavitated chronic lung lesions.

Asunto(s)

RESUMEN

The liquidus temperature curve that characterizes the boundary between the liquid methanol/water mixture and its coexistence with ice Ih is determined using the direct-coexistence method. Several methanol concentrations and pressures of 0.1, 50, and 100 MPa are considered. In this study, we used the TIP4P/Ice model for water and two different models for methanol: OPLS and OPLS/2016, using the geometric rule for the Lennard-Jones cross interactions. We compared our simulation results with available experimental data and found that this combination of models reproduces the liquidus curve for methanol mole fractions reasonably well, up to xm = 0.3 at p = 0.1 MPa. The freezing point depression of these mixtures is calculated and compared to experimental results. We also analyzed the effect of pressure on the liquidus curve and found that both models also reproduce the experimental decrease of the liquidus temperatures as the pressure increases qualitatively well.

RESUMEN

La melioidosis es una enfermedad endémica en el suroeste asiático y Oceanía y está causada por la infección por el bacilo gramnegativo Burkholderia pseudomallei. Se estudian 15 pacientes adultos de Colombia con diagnóstico microbiológico de melioidosis pulmonar. Se revisaron 15 radiografías de tórax y 10 tomografías computarizadas (TC) de tórax. De los 15 pacientes, el 87% tenía criterios de infección aguda y el 13%, de infección crónica. Los hallazgos más frecuentes en la radiografía de tórax fueron: consolidación (86%), nódulos (26%) y cavitación (20%). En la tomografía computarizada se encontraron áreas de consolidación y nódulos en el 90% de los casos. En el 60% de los pacientes, las áreas de consolidación fueron de predominio basal y central. En el 50% de los casos se evidenciaron áreas de cavitación. Se evidenció derrame pleural en el 60% y adenopatías mediastínicas en el 30% de los casos. En los pacientes con presentación aguda (n=8), los hallazgos visualizados incluyeron: nódulos (100%), patrón mixto con nódulos y consolidación (87%), derrame pleural (88%) y adenopatías mediastínicas (25%). Los pacientes con melioidosis crónica (n=2) presentaron cavitación. La infección pulmonar aguda por B. Pseudomallei cursa con manifestaciones radiológicas similares a neumonías de otra etiología. En zonas endémicas debe considerarse la posibilidad de melioidosis aguda en el diagnóstico diferencial de nódulos pulmonares, y de melioidosis crónica en el diagnóstico diferencial de lesiones pulmonares crónicas cavitadas.(AU)

Melioidosis is an endemic disease in Southeast Asia and Oceania caused by the gram-negative bacillus Burkholderia pseudomallei. We studied 15 adult patients from Colombia with microbiologically diagnosed pulmonary melioidosis. We reviewed 15 chest X-rays and 10 chest computed tomography (CT) studies. Of the 15 patients, 87% met the criteria for acute infection and 13% met the criteria for chronic infection. The most common findings on chest X-rays were consolidation (86%), nodules (26%), and cavitation (20%). On CT studies, consolidation and nodules were observed in 90% of cases; the areas of consolidation were predominantly located in the basal and central zones in 60%. Areas of cavitation were observed in 50%, pleural effusion in 60%, and mediastinal lymph nodes in 30%. In patients with acute pulmonary melioidosis (n=8), the findings observed were nodules (100%), mixed pattern with nodules and consolidation (87%), pleural effusion (88%), and mediastinal lymph nodes (25%). The two patients with chronic pulmonary melioidosis both had cavitation. Acute lung infection with B. Pseudomallei has radiologic manifestations similar to those of pneumonia due to other causes. In areas where the disease is endemic, it is essential to include acute melioidosis in the differential diagnosis of pulmonary nodules and chronic melioidosis in the differential diagnosis of cavitated chronic lung lesions.(AU)

Asunto(s)

RESUMEN

Melioidosis is an endemic disease in Southeast Asia and Oceania caused by the gram-negative bacillus Burkholderia pseudomallei. We studied 15 adult patients from Colombia with microbiologically diagnosed pulmonary melioidosis. We reviewed 15 chest X-rays and 10 chest computed tomography (CT) studies. Of the 15 patients, 87% met the criteria for acute infection and 13% met the criteria for chronic infection. The most common findings on chest X-rays were consolidation (86%), nodules (26%), and cavitation (20%). On CT studies, consolidation and nodules were observed in 90% of cases; the areas of consolidation were predominantly located in the basal and central zones in 60%. Areas of cavitation were observed in 50%, pleural effusion in 60%, and mediastinal lymph nodes in 30%. In patients with acute pulmonary melioidosis (n=8), the findings observed were nodules (100%), mixed pattern with nodules and consolidation (87%), pleural effusion (88%), and mediastinal lymph nodes (25%). The two patients with chronic pulmonary melioidosis both had cavitation. Acute lung infection with B. Pseudomallei has radiologic manifestations similar to those of pneumonia due to other causes. In areas where the disease is endemic, it is essential to include acute melioidosis in the differential diagnosis of pulmonary nodules and chronic melioidosis in the differential diagnosis of cavitated chronic lung lesions.

RESUMEN

Southern South American Proteaceae thrive on young volcanic substrates, which are extremely low in plant-available phosphorus (P). Most Proteaceae exhibit a nutrient-acquisition strategy based on the release of carboxylates from specialized roots, named cluster roots (CR). Some Proteaceae colonize young volcanic substrates which has been related to CR functioning. However, physiological functioning of other Proteaceae on recent volcanic substrates is unknown. We conducted an experiment with seedlings of five Proteaceae (Gevuina avellana, Embothrium coccineum, Lomatia hirsuta, L. ferruginea, and L. dentata) grown in three volcanic materials. Two of them are substrates with very low nutrient concentrations, collected from the most recent deposits of the volcanoes Choshuenco and Calbuco (Chile). The other volcanic material corresponds to a developed soil that exhibits a high nutrient availability. We assessed morphological responses (i.e., height, biomass, and CR formation), seed and leaf macronutrient and micronutrient concentrations and carboxylates exuded by roots. The results show that G. avellana was less affected by nutrient availability of the volcanic substrate, probably because it had a greater nutrient content in its seeds and produced large CR exuding carboxylates that supported their initial growth. Embothrium coccineum exhibited greater total plant height and leaf P concentration than Lomatia species. In general, in all species leaf macronutrient concentrations were reduced on nutrient-poor volcanic substrates, while leaf micronutrient concentrations were highly variable depending on species and volcanic material. We conclude that Proteaceae from temperate rainforests differ in their capacity to grow and acquire nutrients from young and nutrient-poor volcanic substrates. The greater seed nutrient content, low nutrient requirements (only for G. avellana) and ability to mobilize nutrients help explain why G. avellana and E. coccineum are better colonizers of recent volcanic substrates than Lomatia species.

RESUMEN

A taxonomic checklist of Chalcidoidea (Hymenoptera) associated with Bruchinae (Coleoptera: Chrysomelidae) is presented. A total of 139 species of Chalcidoidea or unidentified species to genus are reported as primary parasitoids. The valid name, primary host(s) (animal and plant taxa), distribution and references for each species are listed.

Asunto(s)

RESUMEN

In the past few decades great effort has been devoted to the study of water confined in hydrophobic geometries at the nanoscale (tubes and slit pores) due to the multiple technological applications of such systems, ranging from drug delivery to water desalination devices. To our knowledge, neither numerical/theoretical nor experimental approaches have so far reached a consensual understanding of structural and transport properties of water under these conditions. In this work, we present molecular dynamics simulations of TIP4P/2005 water under different nanoconfinements (slit pores or nanotubes, with two degrees of hydrophobicity) within a wide temperature range. It has been found that water is more structured near the less hydrophobic walls, independently of the confining geometries. Meanwhile, we observe an enhanced diffusion coefficient of water in both hydrophobic nanotubes. Finally, we propose a confined Stokes-Einstein relation to obtain the viscosity from diffusivity, whose result strongly differs from the Green-Kubo expression that has been used in previous works. While viscosity computed with the Green-Kubo formula (applied for anisotropic and confined systems) strongly differs from that of the bulk, viscosity computed with the confined Stokes-Einstein relation is not so much affected by the confinement, independently of its geometry. We discuss the shortcomings of both approaches, which could explain this discrepancy.

RESUMEN

Background. The cannabinoid hyperemesis syndrome (CHS) was first described in 2004. It is considered as a functional gastrointestinal syndrome characterized by the presence of nausea, severe and cyclic morning vomiting, epigastric abdominal pain, hot water bathing for symptom relief, in patients that use cannabis regularly and has a resolution of the syndrome after cessation of cannabis consumption. Clinical Case. Report of a 29 year old male, with daily consumption of cannabis, with history of intense epigastric abdominal pain and recurrent vomiting that partially responded to the use of antispasmodics. After 4 visits to the emergency department he was hospitalized for study and treatment. Laboratory and image exploration are carried out without positive results for organic disease. Therefore, a functional gastrointestinal syndrome is thought, and a cannabinoid hyperemesis syndrome was suspected. A psychiatric evaluation is carried out, diagnosing a cannabis use disorder. Discussion and conclusion. CHS is a syndrome that has been described recently and is not usually considered as a differential diagnosis for patients with hyperemesis. However, the current high prevalence of cannabis consumption, will probably lead to a more frequent presentation of the syndrome at different health providers. Therefore, it is important to diffuse and update the knowledge about this syndrome to recognize it and develop a timely treatment, avoiding medical complications from invasive exploratory methods and the use of unnecessary resources. (AU)

Asunto(s)

RESUMEN

We analyze the water vapour-liquid and solid-liquid phase transitions from the perspective of hydrogen bond networks. Using molecular dynamics simulation data for the TIP4P/2005 and TIP4P/ice water models, we built hydrogen bond networks in the neighbourhood of the transitions. We studied the behaviour of some topological network properties: the average degree, clustering coefficient, and average path length. We found that these properties exhibit a discontinuity while approaching a phase transition region, similar to those that appear for some thermodynamic properties in the same region. This approach can be extended to characterize other water phase transitions. Besides, it can also be applied to study the phase transitions of other hydrogen-bonded substances or to other scenarios whose relevant "interaction" could be identified together with a "proper criterion" defined in an analogous way as in the case of hydrogen bonded systems.

RESUMEN

Despite considerable efforts over more than two decades, our knowledge of the interactions in electrolyte solutions is not yet satisfactory. Not even one of the most simple and important aqueous solutions, NaCl(aq), escapes this assertion. A requisite for the development of a force field for any water solution is the availability of a good model for water. Despite the fact that TIP4P/2005 seems to fulfill the requirement, little work has been devoted to build a force field based on TIP4P/2005. In this work, we try to fill this gap for NaCl(aq). After unsuccessful attempts to produce accurate predictions for a wide range of properties using unity ionic charges, we decided to follow recent suggestions indicating that the charges should be scaled in the ionic solution. In this way, we have been able to develop a satisfactory non-polarizable force field for NaCl(aq). We evaluate a number of thermodynamic properties of the solution (equation of state, maximum in density, enthalpies of solution, activity coefficients, radial distribution functions, solubility, surface tension, diffusion coefficients, and viscosity). Overall the results for the solution are very good. An important achievement of our model is that it also accounts for the dynamical properties of the solution, a test for which the force fields so far proposed failed. The same is true for the solubility and for the maximum in density where the model describes the experimental results almost quantitatively. The price to pay is that the model is not so good at describing NaCl in the solid phase, although the results for several properties (density and melting temperature) are still acceptable. We conclude that the scaling of the charges improves the overall description of NaCl aqueous solutions when the polarization is not included.

RESUMEN

BACKGROUND: Lower respiratory tract infection by respiratory syncytial virus (RSV) is the most frequent cause of admission in children under 2 years old. The RSV subgroups A and B may circulate simultaneously. We aimed to determine whether clinical differences exist between RSV subgroups A and B. Additionally, we tested the sensitivity of the rapid antigen detection test (RADT) based on immunochromatography in diagnosing subgroups A and B, taking the polymerase chain reaction assay (RT-PCR) as reference. METHODS: A retrospective observational study was performed in a tertiary hospital from October 2013 to March 2014. Clinical records and analytical variables of all children under 5 admitted with lower respiratory tract infection and RT-PCR positive for RSV in nasal lavage were consulted. Previously, the RADT for RSV had been performed from the same sample. RESULTS: A total of 198 children under 5 were diagnosed with RSV by RT-PCR: 55 (28%) were RSV-A, 132 (67%) RSV-B and 11 (5%) were positive for both subgroups. No differences were observed between subgroups in medical history, symptoms, radiological and analytical findings, and severity. The sensitivity of RADT for RSV was 52%, higher for RSV-A (69%) than for RSV-B (44%, p=0.001). CONCLUSIONS: The two RSV subgroups were indistinguishable in symptoms and prognosis. The sensitivity of RADT compared to RT-PCR was low and limits its usefulness for clinical decision-making. Key words. Respiratory syncytial virus. RSV subgroups. Rapid antigen detection test. Reverse transcription polymerase chain reaction.

Asunto(s)

RESUMEN

Fundamento: La infección del tracto respiratorio inferior por virus respiratorio sincitial (VRS) es la causa más frecuente de ingreso en menores de 2 años. Los subgrupos de VRS A y B pueden circular indistintamente. Nuestro objetivo fue determinar si existían diferencias clínicas entre los VRS subgrupo A y B, y si la sensibilidad del test de detección rápida de antígeno del VRS por inmunocromatografía difiere de la técnica de referencia (RT-PCR). Material y métodos: Estudio retrospectivo, observacional realizado en el hospital terciario desde octubre de 2013 a marzo de 2014. Se consultó la historia clínica y las analíticas de los niños menores de 5 años ingresados en por infección respiratoria de vías bajas con RT-PCR positivo a VRS en una muestra de lavado nasal. De la misma muestra previamente se había realizado el test de detección rápida de antígeno de VRS. Resultados: Se confirmaron 198 niños menores de 5 años para VRS mediante RT-PCR: 55 (28%) fueron VRS-A, 132 (67%) VRS-B y 11 (5%) fueron positivos para ambos subgrupos. No encontramos diferencias entre subgrupos en antecedentes, clínica, radiología, analítica y gravedad. La sensibilidad del test de detección rápida fue 52%, mayor para VRS-A (69%) que para VRS-B (44%, p=0,001). Conclusiones: Los dos subgrupos de VRS fueron indistinguibles por su presentación clínica y pronóstico. La sensibilidad del test rápido en comparación con la RT-PCR fue baja, lo que limita su utilidad en la toma de decisiones clínicas (AU)

Background: Lower respiratory tract infection by respiratory syncytial virus (RSV) is the most frequent cause of admission in children under 2 years old. The RSV subgroups A and B may circulate simultaneously. We aimed to determine whether clinical differences exist between RSV subgroups A and B. Additionally, we tested the sensitivity of the rapid antigen detection test (RADT) based on immunochromatography in diagnosing subgroups A and B, taking the polymerase chain reaction assay (RT-PCR) as reference. Methods: A retrospective observational study was performed in a tertiary hospital from October 2013 to March 2014. Clinical records and analytical variables of all children under 5 admitted with lower respiratory tract infection and RT-PCR positive for RSV in nasal lavage were consulted. Previously, the RADT for RSV had been performed from the same sample. Results: A total of 198 children under 5 were diagnosed with RSV by RT-PCR: 55 (28%) were RSV-A, 132 (67%) RSVB and 11 (5%) were positive for both subgroups. No differences were observed between subgroups in medical history, symptoms, radiological and analytical findings, and severity. The sensitivity of RADT for RSV was 52%, higher for RSV-A (69%) than for RSV-B (44%, p=0.001). Conclusions: The two RSV subgroups were indistinguishable in symptoms and prognosis. The sensitivity of RADT compared to RT-PCR was low and limits its usefulness for clinical decision-making (AU)

Asunto(s)

RESUMEN

In this work, we present an extension of the constant force approach [P. Orea and G. Odriozola, J. Chem. Phys. 138, 214105 (2013)] to the case of potentials with multiple discontinuities. To illustrate the method, we selected the square well potential of range λ=1.5 that exhibits two discontinuities. Square well single phase properties, vapor-liquid phase diagram, and surface tension were calculated and compared with available simulation data. Besides, we analyzed the internal energies of a square well plus a square shoulder potential having three discontinuities. For both potentials, a good agreement has been found when compared with results of other simulation techniques (discontinuous molecular dynamics and Monte Carlo methods). This extension can be easily implemented to more general and efficient continuous molecular dynamics packages (HOOMD, GROMACS, NAMD, etc.).

RESUMEN

La hemosiderosis pulmonar idiopática es una enfermedad muy poco frecuente, de inicio fundamentalmente en edad pediátrica. A pesar de su baja incidencia, debemos tenerla en cuenta ante un caso de anemia microcítica ferropénica persistente, a la que se asocie sintomatología respiratoria. El diagnóstico es de sospecha, apoyándonos en la radiología, siendo fundamental el lavado broncoalveolar y la exclusión de otras causas de hemorragia alveolar difusa. Revisamos los aspectos clínicos, diagnósticos y terapéuticos a propósito de 2 casos de esta entidad (AU)

Idiopathic pulmonary hemosiderosis is an infrequent disease, with debut mainly in childhood. In spite of its low incidence, we should consider this disease in case of persistent microcytic iron deficiency anemia, with respiratory symptoms associated. The diagnosis is supported by the combination of compatible clinical and radiologycal findings, the ending of hemosiderin-laden alveolar macrophages on the broncoalveolar lavage, and is essential to exclude other causes of alveolar haemorrhage. The diagnostic and therapeutic features are reviewed after the presentation of two clinical cases of this entity (AU)

Asunto(s)

RESUMEN

Oozetetes lucidus sp. nov. (Hymenoptera: Eupelmidae) is described from Colombia, South America, and through macrophotography compared with all described species in the bucheri species-group of Oozetetes De Santis. An illustrated key modified from Gibson (2004) is provided to distinguish females of the six described species of this group.

Asunto(s)

RESUMEN

The solubility of NaCl in water is evaluated by using three force field models: Joung-Cheatham for NaCl dissolved in two different water models (SPC/E and TIP4P/2005) and Smith Dang NaCl model in SPC/E water. The methodology based on free-energy calculations [E. Sanz and C. Vega, J. Chem. Phys. 126, 014507 (2007)] and [J. L. Aragones et al., J. Chem. Phys. 136, 244508 (2012)] has been used, except, that all calculations for the NaCl in solution were obtained by using molecular dynamics simulations with the GROMACS package instead of homemade MC programs. We have explored new lower molalities and made longer runs to improve the accuracy of the calculations. Exploring the low molality region allowed us to obtain an analytical expression for the chemical potential of the ions in solution as a function of molality valid for a wider range of molalities, including the infinite dilute case. These new results are in better agreement with recent estimations of the solubility obtained with other methodologies. Besides, two empirical simple rules have been obtained to have a rough estimate of the solubility of a certain model, by analyzing the ionic pairs formation as a function of molality and/or by calculating the difference between the NaCl solid chemical potential and the standard chemical potential of the salt in solution.

RESUMEN

La parotiditis crónica recurrente es una patología que cursa con inflamación parotídea unilateral o bilateral. Afecta a edades pediátricas y tiende a desaparecer con la edad. El objetivo es presentar esta patología infrecuente que, sin embargo, es de fácil diagnóstico y manejo de forma ambulatoria. Se presentan dos casos de esta patología de nuestro centro. Esta patología puede ser tratada de forma ambulatoria con analgesia, antiinflamatorios y, en caso de sobreinfección bacteriana, adjuntando antibioterapia. Las pruebas complementarias indicadas son la ecografía y la analítica sanguínea. Es una patología con buen pronóstico y tratamiento simple. Es importante realizar un buen diagnóstico diferencial. Suele desaparecer conforme el paciente se acerca a la edad adolecente (AU)

Infantile recurrent parotitis is a disease characterized by unilateral or bilateral parotid swelling. It appears in childhood and usually disappears during adolescence. The objective is to present this rare disease which has an easy treatment and diagnosis. We report two cases of this disease from our hospital. This condition can be treated with outpatient treatment, with analgesics, anti-inflammatory drugs and, if there is bacterial infection, also with antibiotics. As additional tests, blood tests and ultrasound are recommended. It is a disease with good prognosis and simple treatment. Differential diagnosis is very important. It usually disappears as the patient approaches the adolescence (AU)

Asunto(s)

RESUMEN

In this work, we present an equation of state for an interesting soft-core continuous potential [G. Franzese, J. Mol. Liq. 136, 267 (2007)] which has been successfully used to model the behavior of single component fluids that show some water-type anomalies. This equation has been obtained using discrete perturbation theory. It is an analytical expression given in terms of density, temperature, and the set of parameters that characterize the intermolecular interaction. Theoretical results for the vapor-liquid phase diagram and for supercritical pressures are compared with previous and new simulation data and a good agreement is found. This work also clarifies discrepancies between previous Monte Carlo and molecular dynamics simulation results for this potential.