Effect of substrate mismatch, orientation, and flexibility on heterogeneous ice nucleation.

Heterogeneous nucleation is the main path to ice formation on Earth. The ice nucleating ability of a certain substrate is mainly determined by both molecular interactions and the structural mismatch between the ice and the substrate lattices. We focus on the latter factor using molecular simulations of the mW model. Quantifying the effect of structural mismatch alone is challenging due to its coupling with molecular interactions. To disentangle both the factors, we use a substrate composed of water molecules in such a way that any variation on the nucleation temperature can be exclusively ascribed to the structural mismatch. We find that a 1% increase in structural mismatch leads to a decrease of ∼4 K in the nucleation temperature. We also analyze the effect of orientation of the substrate with respect to the liquid. The three main ice orientations (basal, primary prism, and secondary prism) have a similar ice nucleating ability. We finally assess the effect of lattice flexibility by comparing substrates where molecules are immobile to others where a certain freedom to fluctuate around the lattice positions is allowed. Interestingly, we find that the latter type of substrate is more efficient in nucleating ice because it can adapt its structure to that of ice.

Beyond lectures and practical courses: Teaching pharmacology using imaginative pedagogical tools.

Pharmacology has broadened its scope considerably in recent decades. Initially, it was of interest to chemists, doctors and pharmacists. In recent years, however, it has been incorporated into the teaching of biologists, molecular biologists, biotechnologists, chemical engineers and many health professionals, among others. Traditional teaching methods, such as lectures or laboratory work, have been superseded by the use of new pedagogical approaches to enable a better conceptualization and understanding of the discipline. In this article, we present several new methods that have been used in Spanish universities. Firstly, we describe a teaching network that has allowed the sharing of pedagogical innovations in Spanish universities. A European experience to improve prescribing safety is described in detail. The use of popular films and medical TV series in biomedical students shows how these audiovisual resources can be helpful in teaching pharmacology. The use of virtual worlds is detailed to introduce this new approach to teaching. The increasingly important area of the social aspects of pharmacology is also considered in two sections, one devoted to social pharmacology and the other to the use of learning based on social services to improve understanding of this important area. Finally, the use of Objective Structured Clinical Evaluation in pharmacology allows to know how this approach can help to better evaluate clinical pharmacology students. In conclusion, this article allows to know new pedagogical methods resources used in some Spanish universities that may help to improve the teaching of pharmacology.

Obtaining and evaluating of enzymatic extracts from hairless canary seed (CDC Maria) as gluten-free bread-improving agents.

In this study, enzyme extracts were obtained from hairless canary seeds (CDC Maria) and used as gluten-free bread improvers. The enzyme extraction was done with a specific protein buffer solution and subsequent centrifugation. The supernatant was called crude enzyme extract, a fraction of this extract was refrigerated (CE) and another fraction was lyophilized (CEL). The lyoprotective effect of corn fiber (CEL + CF), maltodextrin (CEL + M), and inulin (CEL + I) was evaluated. Each enzyme extract was added to a gluten-free bread at 0.25%, 0.5%, 0.75% and 1% (w/w). The quality of the gluten-free bread was determined by external and internal characteristically, physical and sensory analysis: analysis of the lamella thickness, the shape factor of pores, the final volume, the aeration percentage, the texture profile analysis, the pore size distribution and shelf-life time. The results showed that the formulation with CEL at 0.5% (w/w) significantly improved the gluten-free bread quality properties, generating an increase of the final volume and aeration percentage, a reduction of the firmness, chewiness and sample aging, and a finer and more uniform crumb structure when compared to a control sample (P < 0.001). This study revealed the potential of a food-improving additive obtained from a natural origin with a high-level production in Argentina.

Growth rate of CO2 and CH4 hydrates by means of molecular dynamics simulations.

CO2 and CH4 hydrates are of great importance both from an energetic and from an environmental point of view. It is therefore highly relevant to quantify and understand the rate with which they grow. We use molecular dynamics simulations to shed light on the growth rate of these hydrates. We put the solid hydrate phase in contact with a guest aqueous solution in equilibrium with the pure guest phase and study the growth of both hydrates at 400 bars with temperature. We compare our results with previous calculations of the ice growth rate. We find a growth rate maximum as a function of the supercooling in all cases. The incorporation of guest molecules into the solid structure strongly decelerates hydrate growth. Consistently, ice grows faster than either hydrate and the CO2 hydrate grows faster than the CH4 one because of the higher solubility of CO2. We also quantify the molecular motion required to build the solids under study and find that the distance traveled by liquid molecules exceeds by orders of magnitude that advanced by any solid. Less molecular motion is needed in order for ice to grow as compared to the hydrates. Moreover, when temperature increases, more motion is needed for solid growth. Finally, we find a good agreement between our growth rate calculations and experiments of hydrate growth along the guest-solution interface. However, more work is needed to reconcile experiments of hydrate growth toward the solution among each other and with simulations.

Adaptaciones de la Enseñanza Anatómica Durante el COVID-19 en la Universidad Complutense de Madrid. Evaluación de los Estudiantes / Adaptations of Anatomical Teaching During COVID-19 at the University Complutense of Madrid. Evaluation by the Students

Las restricciones por la pandemia del COVID-19 supusieron la transición abrupta a una enseñanza online tanto del contenido teórico como práctico y de la evaluación final de las asignaturas que imparte el departamento en varias titulaciones. En previsión de que el siguiente curso académico 2020-21 se vería totalmente afectado, se desarrollaron una serie de materiales didácticos propios, como la elaboración de guiones de teoría y práctica que incorporaron imágenes de modelos anatómicos, prosecciones, anatomía radiológica y anatomía ecográfica. La percepción de esta innovación fue evaluada por los estudiantes a través de una encuesta en línea y sus respuestas mediante una escala tipo Likert. Participaron 346 estudiantes de las titulaciones de Fisioterapia (n= 66), Medicina (n= 169), Podología (n= 44) y Terapia Ocupacional (n= 67). Las puntuaciones medias más altas correspondieron a los estudiantes de Podología y Terapia Ocupacional, ambas presentaron diferencias significativas con los otros tres subgrupos de alumnos (p<.0001). El puntaje promedio más bajo correspondió a los estudiantes de Medicina de segundo año académico que presentó significancia con los otros cuatro subgrupos de estudiantes (p<.0001). Se analizaron las carencias del sistema educativo en la Universidad Complutense de Madrid reveladas por la pandemia del Covid19. Esta crisis ha puesto de manifiesto la necesidad de que los educadores médicos en general y los anatomistas en particular estén capacitados en el uso de la tecnología disponible y en la creación de sus propios materiales didácticos multimedia.

SUMMARY: Restrictions due to COVID-19 pandemic meant an abrupt transition to online teaching. This change affected teaching, practical sessions and assessments of the subjects taught by the department in various degrees. In anticipation that the following academic year 2020-21 would be totally affected, a series of didactic materials were therefor developed. These materials included the preparation of theory and practice scripts that incorporated images of anatomical models, pro-sections, radiological anatomy, and ultrasound anatomy. Perceptions by the students of these innovations were recorded through an online survey and their responses evaluated through a Likert-type scale. 346 students from Physiotherapy (n= 66), Medicine (n= 169), Podiatry (n= 44) and Occupational Therapy (n= 67) degrees participated. The highest average scores corresponded to the students of Podiatry and Occupational Therapy, both presented significant differences with the other three subgroups of students (p<.0001). The lowest average score corresponded to medical students in their second academic year, which presented significance with the other four subgroups of students (p<.0001). The shortcomings of the educational system of the Complutense University of Madrid that were highlighted by the COVID-19 pandemic were analyzed. This crisis underscored the need for medical educators in general, and anatomists in particular, to be trained in the use of available technology and to produce their own multimedia teaching materials.

Homogeneous nucleation rate of methane hydrate formation under experimental conditions from seeding simulations.

In this work, we shall estimate via computer simulations the homogeneous nucleation rate for the methane hydrate at 400 bars for a supercooling of about 35 K. The TIP4P/ICE model and a Lennard-Jones center were used for water and methane, respectively. To estimate the nucleation rate, the seeding technique was employed. Clusters of the methane hydrate of different sizes were inserted into the aqueous phase of a two-phase gas-liquid equilibrium system at 260 K and 400 bars. Using these systems, we determined the size at which the cluster of the hydrate is critical (i.e., it has 50% probability of either growing or melting). Since nucleation rates estimated from the seeding technique are sensitive to the choice of the order parameter used to determine the size of the cluster of the solid, we considered several possibilities. We performed brute force simulations of an aqueous solution of methane in water in which the concentration of methane was several times higher than the equilibrium concentration (i.e., the solution was supersaturated). From brute force runs, we infer the value of the nucleation rate for this system rigorously. Subsequently, seeding runs were carried out for this system, and it was found that only two of the considered order parameters were able to reproduce the value of the nucleation rate obtained from brute force simulations. By using these two order parameters, we estimated the nucleation rate under experimental conditions (400 bars and 260 K) to be of the order of log10 (J/(m3 s)) = -7(5).

Trend changes in the incidence of benign parotid tumours in the last 30 years in a Spanish population.

PURPOSE: To study the demographics and clinical characteristics of benign parotid tumours, focusing on the evolution of the incidence of Warthin tumour (WT) in recent years. METHODS: A retrospective observational study is designed of patients diagnosed with a benign parotid tumour in a single tertiary hospital centre, from 1994 to 2021. The evaluation of the relationship between the different variables, and the changes in tumour incidence, is carried out using an analysis of standardized residuals. RESULTS: The study evaluated 279 patients, and the total of benign parotid tumours was 291. The most frequent type of tumour was pleomorphic adenoma (PA) (52.7%), followed by WT (37.6%). WT was more frequent in men (79%), and PA in women (55.8%). Smoking history is significantly high in patients with WT (83%), as well as mid-age, compared to PA. CONCLUSIONS: It seems to be an increase in the proportion of WT compared to PA in recent years. These changes can be concerning tobacco use and older patients at diagnosis in our series.

Importancia del conocimiento óptimo de los profesionales sanitarios en el diagnóstico inicial de la hipertensión arterial / Importance of the optimal knowledge of healthcare professionals in the initial diagnosis of high blood pressure

No disponible

Phase diagram of the NaCl-water system from computer simulations.

NaCl aqueous solutions are ubiquitous. They can crystallize into ice, NaCl, or NaCl · 2H2O depending on the temperature-concentration conditions. These crystallization transitions have important implications in geology, cryopreservation, or atmospheric science. Computer simulations can help understand the crystallization of these solids, which requires a detailed knowledge of the equilibrium phase diagram. We use molecular simulations in which we put at contact the solution with the solid of interest to determine points of the solid-solution coexistence lines. We follow two different approaches, one in which we narrow down the melting temperature for a given concentration and the other in which we equilibrate the concentration for a given temperature, obtaining consistent results. The phase diagram thus calculated for the selected model (TIP4P/2005 for water molecules and Joung-Cheatham for the ions) correctly predicts coexistence between the solution and ice. We were only able to determine NaCl · 2H2O-solution coexistence points at higher temperatures and concentrations than in the experiment, so we could not establish a direct comparison in this case. On the other hand, the model underestimates the concentration of the solution in equilibrium with the NaCl solid. Our results, alongside other literature evidence, seem to indicate that ion-ion interactions are too strong in the model. Our work is a good starting point for the improvement of the potential model and for the study of the nucleation kinetics of the solid phases involved in the phase diagram.

Homogeneous nucleation of NaCl in supersaturated solutions.

The seeding method is an approximate approach to investigate nucleation that combines molecular dynamics simulations with classical nucleation theory. Recently, this technique has been successfully implemented in a broad range of nucleation studies. However, its accuracy is subject to the arbitrary choice of the order parameter threshold used to distinguish liquid-like from solid-like molecules. We revisit here the crystallization of NaCl from a supersaturated brine solution and show that consistency between seeding and rigorous methods, like Forward Flux Sampling (from previous work) or spontaneous crystallization (from this work), is achieved by following a mislabelling criterion to select such threshold (i.e. equaling the fraction of the mislabelled particles in the bulk parent and nucleating phases). This work supports the use of seeding to obtain fast and reasonably accurate nucleation rate estimates and the mislabelling criterion as one giving the relevant cluster size for classical nucleation theory in crystallization studies.

Non-destructive Near Infrared Spectroscopy for the labelling of frozen Iberian pork loins.

Iberian pigs fed on acorns and pasture were slaughtered from January until March of 2018 and 2019. The meat from those Iberian pigs is a seasonal food that only can be found fresh, at the marketplace, during a limit period of the year. Selling frozen-thawed meat is a legal practice, but consumers must be informed about it on the product label. However, to declare as fresh meat, meat previously frozen, is one of the most frequent meat frauds. The present study compares the performance of two rather different Near Infrared Spectroscopy instruments, based on Fourier Transform and Linear Variable Filter technologies, for the in-situ detection of fresh and frozen-thawed acorns-fed Iberian pig loins using Partial Least Discriminant Analysis (PLS-DA). The performance of the models developed for both instruments offered a very high discriminant ability. Furthermore, the models showed consistent results and interpretation when were evaluated with several scalars and graphical methods.

Efficacy of cognitive intervention programs in amnesic mild cognitive impairment: A systematic review.

BACKGROUND: Amnesic mild cognitive impairment (aMCI) is considered a prodromal stage of Alzheimer's disease. Given the absence of an effective pharmacological treatment for aMCI, increasing numbers of studies are attempting to understand how cognitive interventions could benefit aMCI patients. The aim of this systematic review was to evaluate the current evidence regarding the efficacy on cognition of cognitive intervention programs in older adults with aMCI. METHODS: We searched for randomized controlled trials and clinical trials published until March 2020 on PubMed, Web of Science, Cochrane Library, SCOPUS, and OTseeker. A total of 454 works were identified and 7 studies that met the inclusion criteria, were included in this review. PRISMA guidelines were followed and PEDro scale was included for the measurement of the quality of the selected studies. RESULTS: Cognitive interventions showed positive effects on cognition. Cognitive training programs considerably enhanced the Mini Mental State Examination scores. However, no relevant differences in global cognition were found using other assessment tools as DRS-2 or ADAS-Cog Scale. Cognitive training and cognitive rehabilitation programs seemed to improve several cognitive domains as memory, language or executive function in aMCI patients in both post-training and at follow-up analysis. CONCLUSIONS: Our findings support that cognitive interventions can be an effective option for people with aMCI. Cognitive interventions improved global cognitive function post-intervention, but also seemed to enhance some cognitive domains post-intervention and at follow-up. However, more studies are needed to analyze the potential benefits of cognitive intervention on aMCI.

The Young-Laplace equation for a solid-liquid interface.

The application of the Young-Laplace equation to a solid-liquid interface is considered. Computer simulations show that the pressure inside a solid cluster of hard spheres is smaller than the external pressure of the liquid (both for small and large clusters). This would suggest a negative value for the interfacial free energy. We show that in a Gibbsian description of the thermodynamics of a curved solid-liquid interface in equilibrium, the choice of the thermodynamic (rather than mechanical) pressure is required, as suggested by Tolman for the liquid-gas scenario. With this definition, the interfacial free energy is positive, and the values obtained are in excellent agreement with previous results from nucleation studies. Although, for a curved fluid-fluid interface, there is no distinction between mechanical and thermal pressures (for a sufficiently large inner phase), in the solid-liquid interface, they do not coincide, as hypothesized by Gibbs.

Efectos y seguridad del perfluorohexiloctano en la superficie ocular y el endotelio corneal / Effects and safety of perfluorohexyloctane on the eye surface and corneal endothelium

OBJETIVO: Evaluar los efectos y la seguridad del perfluorohexiloctano (F6H8) tópico en la superficie ocular y el endotelio corneal. MÉTODOS: Fueron diagnosticados 45 pacientes (90 ojos) de enfermedad de ojo seco, se seleccionaron y se les prescribió tratamiento con F6H8 durante 6 meses. Las variables en la tinción corneal se documentaron usando la escala National Eye Institute/Industry Workshop (NEI), las variables conjuntivales usando la escala Oxford y los parámetros corneales, como el espesor corneal central, la densidad celular, el coeficiente de variación, la hexagonalidad y el área celular promedio, al inicio del estudio, a los 3 meses y a los 6 meses. Se evaluó también el cumplimiento y la satisfacción. RESULTADOS: El tratamiento con F6H8 redujo la tinción corneal promedio en pacientes cumplidores a una media de −0,84 ± 1,95 a los 3meses (p = 0,001) y a −1,65 ± 2,42 a los 6 meses (p < 0,001). La tinción conjuntival a los 6meses mostró una disminución promedio de −0,13 (p = 0,319). Los parámetros endoteliales no mostraron diferencia significativa, excepto el espesor corneal central, que mostró una disminución estadísticamente significativa (era de 545,30 ± 32,25 μm al comienzo del estudio y 538,40 ± 31,36 μm tras 6 meses, p = 0,009). Al final del estudio, el 46% de los pacientes informaron sentirse subjetivamente mejor, el 40,5% no sintió cambios y el 13,5% se sintió subjetivamente peor. CONCLUSIONES: El tratamiento tópico con F6H8 para la enfermedad de ojo seco no alteró las variables medidas del endotelio corneal, aunque sí mostró mejoría en la tinción corneal y en la satisfacción

OBJECTIVE: To evaluate the effects and safety of topical drops of perfluorohexyloctane (F6H8) on the ocular surface and the corneal endothelium. METHODS: Forty-five patients (90 eyes) diagnosed with dry eye disease were recruited and prescribed treatment with F6H8 as part of a six-month prospective multicentre study. Variables in corneal staining were documented using the National Eye Institute/Industry Workshop scale. The conjunctival variables included using the Oxford scale, as well as corneal parameters, such as central corneal thickness, cell density, coefficient of variation, hexagonality, and mean cell area, at the start of the study, and at 3 months and 6 months. Compliance and satisfaction with the treatment were measured. RESULTS: F6H8 drops reduced mean corneal staining based on the NEI scale in compliant patients to a mean of −0.84 ± 1.95 at 3months (P=.001) and to −1.65 ± 2.42 at 6months (P<.001). Conjunctival staining at 6months showed a mean decrease of −0.13 (P=.319). The endothelial parameters did not show a significant difference, in contrast to the central corneal thickness that showed a statistically significant decrease (545.30 ± 32.25 at the start of the study to 538.40 ± 31.36 after 6months, P=.009). At the end of the study, 46% of patients reported feeling subjectively better, 40.5% felt the same, and 13.5% felt subjectively worse. CONCLUSIONS: Topical treatment with F6H8 for dried eye disease did not alter the measured variables of the corneal endothelium, but showed improvement in corneal staining and satisfaction

Pandemia COVID-19: impacto y reacción rápida de la Urología / COVID-19 Pandemic: Impact and rapid reaction of Urology

La pandemia COVID-19 causada por el virus SARS-CoV-2 ha ocasionado decenas de miles de muertos en España y logrado colapsar los hospitales de la red sanitaria en la Comunidad de Madrid, debido en gran parte a su particular tendencia a causar neumonías graves con necesidad de soporte ventilatorio. Este hecho ha ocasionado el colapso de nuestro centro, llegando a tener una ocupación del 130% de sus camas por enfermos COVID-19, y causando por tanto el cese absoluto de actividad del servicio de urología, la práctica desaparición de la docencia de los residentes y la incorporación de buena parte de la plantilla de urología al grupo de personal médico que atiende a estos pacientes. Para la recuperación de esta elevada cantidad de actividad suspendida será necesaria una priorización de la patología en base a criterios puramente clínicos, para la cual se proponen tablas que recogen la relevancia de cada patología dentro de cada área de la urología. Herramientas brindadas por la tecnología como la formación online o los simuladores quirúrgicos podrán ser útiles para la necesaria restitución de la formación de residentes

The COVID-19 pandemic caused by the SARS-CoV-2 virus has caused tens of thousands of deaths in Spain and has managed to breakdown the healthcare system hospitals in the Community of Madrid, largely due to its tendency to cause severe pneumonia, requiring ventilatory support. This fact has caused our center to collapse, with 130% of its beds occupied by COVID-19 patients, thus causing the absolute cessation of activity of the urology service, the practical disappearance of resident training programs, and the incorporation of a good part of the urology staff into the group of medical personnel attending these patients. In order to recover from this extraordinary level of suspended activity, we will be obliged to prioritize pathologies based on purely clinical criteria, for which tables including the relevance of each pathology within each area of urology are being proposed. Technology tools such as online training courses or surgical simulators may be convenient for the necessary reestablishment of resident education

Effects and safety of perfluorohexyloctane on the eye surface and corneal endothelium. / Efectos y seguridad del perfluorohexiloctano en la superficie ocular y el endotelio corneal.

OBJECTIVE: To evaluate the effects and safety of topical drops of perfluorohexyloctane (F6H8) on the ocular surface and the corneal endothelium. METHODS: Forty-five patients (90 eyes) diagnosed with dry eye disease were recruited and prescribed treatment with F6H8 as part of a six-month prospective multicentre study. Variables in corneal staining were documented using the National Eye Institute/Industry Workshop scale. The conjunctival variables included using the Oxford scale, as well as corneal parameters, such as central corneal thickness, cell density, coefficient of variation, hexagonality, and mean cell area, at the start of the study, and at 3months and 6months. Compliance and satisfaction with the treatment were measured. RESULTS: F6H8 drops reduced mean corneal staining based on the NEI scale in compliant patients to a mean of -0.84 ± 1.95 at 3months (P=.001) and to -1.65 ± 2.42 at 6months (P<.001). Conjunctival staining at 6months showed a mean decrease of -0.13 (P=.319). The endothelial parameters did not show a significant difference, in contrast to the central corneal thickness that showed a statistically significant decrease (545.30 ± 32.25 at the start of the study to 538.40 ± 31.36 after 6months, P=.009). At the end of the study, 46% of patients reported feeling subjectively better, 40.5% felt the same, and 13.5% felt subjectively worse. CONCLUSIONS: Topical treatment with F6H8 for dried eye disease did not alter the measured variables of the corneal endothelium, but showed improvement in corneal staining and satisfaction.

[COVID-19 Pandemic: Impact and rapid reaction of Urology]. / Pandemia COVID-19: impacto y reacción rápida de la Urología.

The COVID-19 pandemic caused by the SARS-CoV-2 virus has caused tens of thousands of deaths in Spain and has managed to breakdown the healthcare system hospitals in the Community of Madrid, largely due to its tendency to cause severe pneumonia, requiring ventilatory support. This fact has caused our center to collapse, with 130% of its beds occupied by COVID-19 patients, thus causing the absolute cessation of activity of the urology service, the practical disappearance of resident training programs, and the incorporation of a good part of the urology staff into the group of medical personnel attending these patients. In order to recover from this extraordinary level of suspended activity, we will be obliged to prioritize pathologies based on purely clinical criteria, for which tables including the relevance of each pathology within each area of urology are being proposed. Technology tools such as online training courses or surgical simulators may be convenient for the necessary reestablishment of resident education.

Seeding approach to nucleation in the NVT ensemble: The case of bubble cavitation in overstretched Lennard Jones fluids.

Simulations are widely used to study nucleation in first order phase transitions due to the fact that they have access to the relevant length and time scales. However, simulations face the problem that nucleation is an activated process. Therefore, rare event simulation techniques are needed to promote the formation of the critical nucleus. The Seeding method, where the simulations are started with the nucleus already formed, has proven quite useful in efficiently providing estimates of the nucleation rate for a wide range of orders of magnitude. So far, Seeding has been employed in the NPT ensemble, where the nucleus either grows or redissolves. Thus, several trajectories have to be run in order to find the thermodynamic conditions that make the seeded nucleus critical. Moreover, the nucleus lifetime is short and the statistics for obtaining its properties is consequently poor. To deal with these shortcomings we extend the Seeding method to the NVT ensemble. We focus on the problem of bubble nucleation in a metastable Lennard Jones fluid. We show that, in the NVT ensemble, it is possible to equilibrate and stabilise critical bubbles for a long time. The nucleation rate inferred from NVT-Seeding is fully consistent with that coming from NPT-Seeding. The former is quite suitable to obtain the nucleation rate along isotherms, whereas the latter is preferable if the dependence of the rate with temperature at constant pressure is required. Care should be taken with finite size effects when using NVT-Seeding. Further work is required to extend NVT seeding to other sorts of phase transitions.