Exploiting intermediate wetting on superhydrophobic surfaces for efficient icing prevention.

HYPOTHESIS: Superhydrophobic surfaces can effectively prevent the freezing of supercooled droplets in technological systems. Droplets on superhydrophobic surfaces commonly not only wet the top asperities (Cassie State), but also partially penetrate into microstructure due to surface properties, environment, and droplet impact occurring in real-world applications. Implications on ice nucleation can be expected and are little explored. It remains elusive how anti-icing surfaces can be designed to exploit intermediate wetting phenomena. EXPERIMENTS: We utilized engineered micro-/nanostructures, specifically micropillars, to modulate the wetting fraction in the microstructure. The behavior of intermediate wetting with supercooling and resulting implications on ice nucleation delay when potential nucleation sites are formed in the microcavities were investigated using experimental, theoretical, and simulation components. FINDINGS: The temperature-dependent wetting fraction in the microstructure increased at supercooled temperatures, partly activated by condensation in the microcavities. At -10/-20 °C, a critical wetting fraction led to maximum ice nucleation delays, with experimental results consistent with theoretical predictions. This critical wetting fraction minimized the effective contact area solid-to-liquid along the partially wetted microstructure. The study establishes physical relations between ice nucleation delays, geometrical surface parameters and wettability properties in the intermediate wetting regime, providing guidance for the design of ice resistant microstructured surfaces.

Retrograde Solubility of Methylammonium Lead Iodide in γ-Butyrolactone Does Not Enhance the Uniformity of Continuously Coated Films.

Halide perovskite thin films can be the centerpiece of high-performance solar cells, light-emitting diodes, and other optoelectronic devices if the films are of high uniformity and relatively free of pinholes and other defects. A common strategy to form dense films from solution has been to generate a high density of nuclei by rapidly increasing supersaturation, for example, by timely application of an antisolvent or forced convection. In this work, we examine the role of retrograde solubility, wherein solubility decreases with increasing temperature, as a means of increasing the nucleation density and film coverage of slot-die-coated methylammonium lead iodide (MAPbI3) from γ-butyrolactone (GBL) solution. Coverage was investigated as a function of the substrate temperature and the presence and temperature of an air knife. Results were considered within the framework of the dimensionless modified Biot number, which quantifies the interplay between evaporation and horizontal diffusion. Moderate temperatures and a heated air knife improved film coverage and morphology by enhanced nucleation up to ∼80 °C. However, despite the dense nucleation enabled by retrograde solubility, slow evaporation as a result of the low vapor pressure of GBL, combined with Ostwald ripening at high temperatures, prevented the deposition of void-free, device-quality films. This work has provided a more detailed understanding of the interplay between perovskite processing, solvent parameters, and film morphology and ultimately indicates the obstacles to forming dense, uniform films from solvents with high boiling points even in the presence of rapid nucleation.

Examining optimism and flourishing as protective factors of suicidality across the adult lifespan: A cross-sectional investigation in three Spanish age groups.

We examined optimism and flourishing as unique protective predictors of suicidality (viz., suicidal ideation and suicidal behaviors) in a cross-sectional study of young adults (18-35 years), middle-aged adults (36-55 years), and older adults (≥56 years). Young adults were found to have higher levels of suicidal ideation and suicidal behaviors compared to middle-aged and older adults. Controlling for depressive symptoms, the results of conducting regression analyses consistently implicated flourishing as a distinct predictor of lower suicidal ideation and suicidal behaviors in young adults and middle-aged adults. However, for older adults, only optimism was found to be a unique predictor of lower suicidal ideation and suicidal behaviors. Implications of the present findings for understanding the differential role of optimism and flourishing in accounting for suicidality across the adult lifespan are discussed.

Highly stable petroleum pitches provide access to the deep glassy state.

Differential scanning calorimetry (DSC) was used to study the fast aging behavior of two petroleum pitch materials despite being only three to five years old. We observe that these highly aromatic pitches with broad distributions of both molecular weight and aromaticity exhibit large enthalpic relaxation endotherms in initial DSC heating scans, and 20-32 °C reductions in the fictive temperature and 0.35-0.87 of θK, which are indicative of aged glasses similar to ultrastable glasses and 20 MA aged amber. Quantifying the degree of thermodynamic stability relative to the Kauzmann temperature vs. the aging time demonstrates that these materials age just as quickly as low fragility metallic glasses. Additionally, we observe that pitches age faster than polymers reported in the literature when compared using down-jump experiments. We hypothesize that the fraction of higher aromaticity of pitch molecules plays a crucial role in faster dynamics. The unique aging behavior and the ability to produce pitches in bulk quantities using pilot-scale equipment, while being possible to tailor their molecular composition, make them a useful material for studying complex aging dynamics in the deep glassy state.

Quasi-2D Model to Predict Solid Microstructure in Drying Thin Films.

The microstructure of solid coatings produced by solution processing is highly dependent on the coupling between growth, solute diffusion, and solvent evaporation. Here, a quasi-2D numerical model coupling drying and solidification is used to predict the transient lateral growth of two adjacent nuclei growing toward each other. Lateral gradients of the solute and solvent influence the evolution of film thickness and solid growth rate. The important process parameters and solvent properties are captured by the dimensionless Peclet number (Pe) and the Biot number (Bi), modified by an aspect ratio defined by the film thickness and distance between nuclei. By variation of Pe and Bi, the evaporation dynamics and aspect ratio are shown to largely determine the coating quality. These findings are applied to drying thin films of crystallizing halide perovskites, demonstrating a convenient process map for capturing the relationship between the modified Bi and well-defined coating regimes, which may be generalized for any solution-processed thin film coating systems.

Engineering Toughness in a Brittle Vinyl Ester Resin Using Urethane Acrylate for Additive Manufacturing.

Thermosetting polymers tend to have a stiffness-toughness trade-off due to the opposing relationship of stiffness and toughness on crosslink density. We hypothesize that engineering the polymer network, e.g., by incorporating urethane oligomers, we can improve the toughness by introducing variations in crosslink density. In this work, we show that a brittle methacrylated Bis-GMA resin (known as DA2) is toughened by adding a commercial urethane acrylate resin (known as Tenacious) in different proportions. The formulations are 3D printed using a vat photopolymerization technique, and their mechanical, thermal, and fracture properties are investigated. Our results show that a significant amount of Tenacious 60% w/w is required to produce parts with improved toughness. However, mechanical properties drop when the Tenacious amount is higher than 60% w/w. Overall, our results show that optimizing the amount of urethane acrylate can improve toughness without significantly sacrificing mechanical properties. In fact, the results show that synergistic effects in modulus and strength exist at specific blend concentrations.

Engineered Interleaved Random Glass Fiber Composites Using Additive Manufacturing: Effect of Mat Properties, Resin Chemistry, and Resin-Rich Layer Thickness.

Standard lay-up fabrication of fiber-reinforced composites (FRCs) suffer from poor out-of-plane properties and delamination resistance. While advanced manufacturing techniques (e.g., interleaving, braiding, and z-pinning) increase delamination resistance in FRCs, they typically result in significant fabrication complexity and limitations, increased manufacturing costs, and/or overall stiffness reduction. In this work, we demonstrate the use of facile digital light processing (DLP) technique to additively manufacture (AM) random glass FRCs with engineered interleaves. This work demonstrates how vat photo-polymerization techniques can be used to build composites layer-by-layer with controlled interleaf material, thickness, and placement. Note that this engineering control is almost impossible to achieve with traditional manufacturing techniques. A range of specimens were printed to measure the effect of interleaf thickness and material on tensile/flexural properties as well as fracture toughness. One important observation was the ≈60% increase in interlaminar fracture toughness achieved by using a tough resin material in the interleaf. The comparison between AM and traditionally manufactured specimens via vacuum-assisted resin transfer molding (VARTM) highlighted the limitation of AM techniques in achieving high mat consolidation. In other words, the volume fraction of AM parts is limited by the wet fiber mat process, and engineering solutions are discussed. Overall, this technique offers engineering control of FRC design and fabrication that is not available with traditional methods.

Predicting the Dynamics and Steady-State Shape of Cylindrical Newtonian Filaments on Solid Substrates.

The spreading of liquid filaments on solid surfaces is of paramount importance to a wide range of applications including ink-jet printing, coating, and direct ink writing (DIW). However, there is a considerable lack of experimental, numerical, and theoretical studies on the spreading of filaments on solid substrates. In this work, we studied the dynamics of spreading of Newtonian filaments via experiment, numerical simulations, and theoretical analysis. More specifically, we used a novel experimental setup to validate a 2D moving mesh computational fluid dynamics (CFD) model. The CFD model is used to determine the effect of processing and fluid parameters on the dynamics of filament spreading. We experimentally showed that for a Newtonian filament, the same spreading dynamics and final shape are obtained when the initial radius is constant, independent of the magnitude in printing parameters. In other words, the only important parameter on the spreading of filaments is the initial filament radius. Using a numerical model, we showed that the initial filament radius manifests itself in two important dimensionless parameters, Bond number, Bo, and viscous timescale, τµ. Furthermore, the results clearly show that the dynamics of spreading are governed by the static advancing contact angle, θs. These three parameters determine a master spreading curve that can be used to predict the spreading of cylindrical filaments on flat substrates. Finally, we developed a theoretical model that was parameterized using experimental data to correlate the steady-state shape of filaments with Bo and θs. These results are particularly applicable for predicting and controlling the dynamics of filaments in DIW and other extrusion-based processes.

The Impact of Stressful Life Events on Suicidal Ideation in Gender Dysphoria: A Moderator Effect of Perceived Social Support.

Factors associated with suicidal ideation in the gender dysphoria population are not completely understood. This high-risk population is more likely to suffer stressful events such as assault or employment discrimination. This study aimed to determine the association of stressful events and social support on suicidal ideation in gender dysphoria and to analyze the moderator effect of social support in relation to stressful events and suicidal ideation. A cross-sectional design was used in a clinical sample attending a public gender identity unit in Spain that consisted of 204 individuals (51.7% birth-assigned males and 48.3% birth-assigned females), aged between 13 and 59 (M = 27.95 years, SD = 9.58). A Structured Clinical Interview, a list of 16 stressful events, and a functional social support questionnaire (Duke-UNC-11) were used during the initial visits to the unit. The data were collected between 2011 and 2012. A total of 50.1% of the sample have had suicidal ideation. The following stressful events were associated with suicidal ideation: homelessness, eviction from home, and having suffered from physical or verbal aggression. Also, there was an inverse relation between perceived social support and suicidal ideation. There was a statistically significant interaction between a specific stressful event (eviction) and perceived social support. The study suggests that the promotion of safer environments could be related to lower suicidal ideation and that networks that provide social support could buffer the association between specific stressful events and suicidal ideation.

Intervenciones en Psicología Positiva para la disminución de la depresión y el fomento del bienestar en personas mayores de 60 años: Una revisión sistemática de la última década (2012-2022) / Interventions in Positive Psychology to reduce depression and promote well-being in the elderly: A systematic review of the last decade (2012-2022)

En los últimos años distintos estudios muestran la eficacia de las intervenciones en Psicología Positiva para mejorar la sintomatología depresiva y el bienestar en población adulta; sin embargo, hay pocos estudios que revisen la eficacia de estas intervenciones en personas de 60 años o más. Objetivo: recoger y sintetizar la evidencia existente en la última década con respecto a las intervenciones en Psicología Positiva en estas personas. Método: se ha realizado una revisión sistemática (RS) que recoge las publicaciones, realizadas entre enero de 2012 y julio de 2022, procedentes de las bases de datos SCOPUS, WOS/Medline y PROQUEST/PsycInfo. Se seleccionaron 944 estudios empíricos, de los cuales 18 cumplieron los criterios de inclusión. Resultados: se presenta evidencia sobre la eficacia de las intervenciones en Psicología Positiva para reducir la sintomatología depresiva e incrementar el bienestar subjetivo y psicológico en personas de estas edades, con efectos superiores a los de otros grupos de control. Esto sucede con programas de intervención en bienestar, al entrenar varias fortalezas- gratitud o perdón junto con otras- o entrenando en mindfulness. Conclusión: estos resultados subrayan la importancia de considerar las intervenciones en Psicología Positiva como terapias complementarias para mejorar la salud mental y la calidad de vida en personas mayores de 60 años.

Recently, different studies have shown the efficacy of interventions in Positive Psychology to improve both depressive symptoms and well-being in adults. However, there are only a few studies that review the efficacy of these interventions in people aged 60 years and older. Objective: synthesize the evidence from the last decade about these interventions in these people. Method: A systematic review was conducted. Publications between 2012 and 2022 -from SCOPUS, WOS/Medline and PROQUEST/PsycInfo- were included. After analyzing 944 empirical works, 18 studies have met the inclusion criteria. Results: the results show the efficacy of interventions in Positive Psychology, both to reduce depressive symptoms, and to increase subjective and psychological well-being in people of these ages, compared to other control groups. These effects are found with interventions on well-being, with interventions on personal strengths -gratitude or forgiveness in combination with sense of humor, empathy, meaning of life or emotional regulation- or through training on mindfulness. Conclusions: The preliminary results point out the importance of interventions in Positive Psychology as complementary therapies to improve the metal health and quality of life in people over 60 years.

A generalized scaling theory for spontaneous spreading of Newtonian fluids on solid substrates.

HYPOTHESIS: There exists a generalized solution for the spontaneous spreading dynamics of droplets taking into account the influence of interfacial tension and gravity. EXPERIMENTS: This work presents a generalized scaling theory for the problem of spontaneous dynamic spreading of Newtonian fluids on a flat substrate using experimental analysis and numerical simulations. More specifically, we first validate and modify a dynamic contact angle model to accurately describe the dependency of contact angle on the contact line velocity, which is generalized by the capillary number. The dynamic contact model is implemented into a two-phase moving mesh computational fluid dynamics (CFD) model, which is validated using experimental results. FINDINGS: We show that the spreading process is governed by three important parameters: the Bo number, viscous timescale τviscous, and static advancing contact angle, θs. More specifically, there exists a master spreading curve for a specific Bo and θs by scaling the spreading time with the τviscous. Moreover, we developed a correlation for prediction of the equilibrium shape of the droplets as a function of both Bo and θs. The results of this study can be used in a wide range of applications to predict both dynamic and equilibrium shape of droplets, such as in droplet-based additive manufacturing.

Influence of central sidechain on self-assembly of glycine-x-glycine peptides.

Low molecular weight gelators (LMWGs) are the subject of intense research for a range of biomedical and engineering applications. Peptides are a special class of LMWG, which offer infinite sequence possibilities and, therefore, engineered properties. This work examines the propensity of the GxG peptide family, where x denotes a guest residue, to self-assemble into fibril networks via changes in pH and ethanol concentration. These triggers for gelation are motivated by recent work on GHG and GAG, which unexpectedly self-assemble into centimeter long fibril networks with unique rheological properties. The propensity of GxG peptides to self-assemble, and the physical and chemical properties of the self-assembled structures are characterized by microscopy, spectroscopy, rheology, and X-ray diffraction. Interestingly, we show that the number, length, size, and morphology of the crystalline self-assembled aggregates depend significantly on the x-residue chemistry and the solution conditions, i.e. pH, temperature, peptide concentration, etc. The different x-residues allow us to probe the importance of different peptide interactions, e.g. π-π stacking, hydrogen bonding, and hydrophobicity, on the formation of fibrils. We conclude that fibril formation requires π-π stacking interactions in pure water, while hydrogen bonding can form fibrils in the presence of ethanol-water solutions. These results validate and support theoretical arguments on the propensity for self-assembly and leads to a better understanding of the relationship between peptide chemistry and fibril self-assembly. Overall, GxG peptides constitute a unique family of peptides, whose characterization will aid in advancing our understanding of self-assembly driving forces for fibril formation in peptide systems.

An active break program (ACTIVA-MENTE) at elementary schools in Chile: study protocol for a pilot cluster randomized controlled trial.

Background: Physical inactivity is prevalent in childhood. Schools can be an ideal context to promote the regular practice of physical activity since children spend there a large part of the day. In this sense, an emerging and current trend is active breaks at school. This article presents a study protocol that seeks to assess the feasibility and effectiveness of an intervention with active breaks (ACTIVA-MENTE program) in a school context on physical activity, on-task classroom behavior, and the physical activity enjoyment in schoolchildren. Methods: The protocol includes children aged 10 to 11 years. Two groups will be randomized (intervention and control groups). The intervention group will use the active break program, ACTIVA-MENTE, which consists of the application of a 4-min, 30-s video with moderate to vigorous-intensity physical activity. These breaks will be taken 6 times a day in the classes for 6 weeks. The total physical activity will be measured with accelerometers (Actigraph wGT3X-BT), the on-task behavior through the Direct Behavior Rating Scale and the level of enjoyment through the Physical Activity Enjoyment Scale. Discussion: Previous research reported that active breaks have positive results in physical activity levels. This study will be one of the few to design active breaks through videos without depending on the presence of a physical education teacher and it can also provide new findings on the effectiveness of an active break's structure (e.g., types of exercises and intensity) on the indicated outcomes. Expected results: It is expected that the ACTIVA-MENTE program can be a suitable program for school settings, potentially increasing physical activity levels, and the commitment to the task, as well as be a pleasant moment for the students. Clinical trial registration: Clinicaltrials.gov, identifier NCT05403996.

Influence of Physical Fitness, Anthropometric Profile, and Biological Maturation on Technical Performance and Enjoyment of Untrained Children Who Participate in Continuous and Fractional Small-Sided Games.

The objective is to determine the relationship between physical fitness, anthropometric measures, and biological maturation as they relate to technical performance in small-sided games (SSGs) of continuous and fractioned regimes. Methodology: A crossover-design study in which 12 children participated in two regimens of SSG (continuous and fractional). At the beginning of the study, all children were evaluated using physical fitness tests (horizontal jump test, vertical jump, cardiorespiratory fitness, and agility), anthropometric profile (weight, height, Body Mass Index (BMI), and waist circumference (WC)), and biological maturation (peak years of growth velocity). All sessions were recorded and analyzed with the Performance Assessment in Team Sports instrument, and at the end of each game each child was asked to answer a scale of enjoyment for physical activity. Results: The results of the paired samples t-test showed no significant differences in the measures of technical performance and perceived enjoyment for the continuous and fractional regimens of SSGs (p > 0.05). The correlation results showed that technical performance in the continuous and fractional regimes was related to agility, horizontal jump, and height, while biological maturation was only related to technical performance in the fractional regimen of SSGs. Perceived enjoyment showed a negative relationship with weight, height, BMI, and WC. Conclusion: The fractional and continuous regimens of SSGs implemented in this study induced similar technical demands and enjoyment. Furthermore, the results suggest that physical fitness, anthropometric profile, and biological maturation may influence the technical performance and enjoyment of SSGs.

Forbidden Secondary Structures Found in Gel-Forming Fibrils of Glycylphenylalanylglycine.

The zwitterionic l-tripeptide glycylphenylalanylglycine self-assembles into very long crystalline fibrils in an aqueous solution, which causes the formation of an exceptionally strong gel phase (G' ∼ 5 × 106 Pa). The Rietveld refinement analysis of its powder X-ray diffraction (PXRD) pattern reveals a unit cell with four peptides forming a P212121 space group and adopting an inverse polyproline II conformation, that is, a right-handed helical structure that occupies the "forbidden" region of the Ramachandran plot. This unusual structure is stabilized by a plethora of intermolecular interactions facilitated by the large number of different functional groups of the unblocked tripeptide. Comparisons of simulated and experimental Fourier transform infrared and vibrational circular dichroism (VCD) amide I' profiles corroborate the PXRD structure. Our experimental setup reduces the sample to a quasi-two-dimensional network of fibrils. We exploited the influence of this reduced dimensionality on the amide I VCD to identify the main fibril axis. We demonstrate that PXRD, vibrational spectroscopy, and amide I simulations provide a powerful toolset for secondary structure and fibril axis determination.

Tensiones culturales en adolescentes migrantes residentes en Chile / Cultural tensions in migrant adolescents living in Chile / Tensões culturais em adolescentes migrantes residentes no Chile

Resumen (analítico) Las migraciones contemporáneas han desafiado significativamente el desarrollo de las parentalidades en el núcleo de la familia transnacional. Resulta de interés acercarnos a las tensiones culturales que afrontan adolescentes migrantes desde sus significados, deconstruyendo lógicas adultocéntricas que los han invisibilizado como sujetos protagónicos. Este estudio contó con la participación de adolescentes migrantes provenientes de Colombia, Haití y Venezuela, cuyas familias residen en Chile. A partir de entrevistas en profundidad, se realizó un análisis desde un enfoque constructivista de los principales resultados respecto a tensiones culturales vivenciadas por los y las adolescentes en el ámbito individual y familiar, destacando en este último los estilos educativos y la apertura cultural, desplegándose distintos mecanismos de resolución o afrontamiento, tales como la integración, resistencia y exclusión.

Abstract (analytical) Contemporary migration patterns have significantly challenged the role of parenting in transnational families. Faced with this scenario, this study enquires about the cultural tensions faced by migrant adolescents through their meanings, deconstructing adultcentered logics that have made them invisible as subjects. This study included the participation of migrant adolescents from Colombia, Haití and Venezuela whose families are living in Chile. Following the indepth interviews, an analysis was carried out using a constructivist approach. The main results highlighted the cultural tensions experienced by adolescents in both individual and family spheres of life. Within their families, they high-lighted cultural differences in terms of educational styles and cultural openness. The adolescents deploy different resolution and/or coping mechanisms, such as integration, resistance and exclusion.

Resumo (analítico) As migrações contemporâneas têm desafiado significativamente o desenvolvimento das relações parentais no seio da família transnacional. Diante desse cenário, interessa abordar as tensões culturais enfrentadas pelos adolescentes migrantes a partir de seus significados, desconstruindo lógicas adultocêntricas que os têm invisibilizado como sujeitos protagonistas. Este estudo contou com a participação de adolescentes migrantes da Colômbia, Haiti e Venezuela, cujas famílias residem no Chile. Partindo das entrevistas em profundidade, procedeu-se uma análise desde um enfoque construtivista dos principais resultados relativos às tensões culturais vivenciadas pelas e pelos adolescentes no âmbito individual e familiar, destaca-se neste último, os estilos educacionais e a abertura cultural, implantando distintos mecanismos de resolução e/ou enfrentamento, tais como a integração, resistência e exclusão.

Changes in the Mechanical Properties of the Horizontal Force-Velocity Profile during a Repeated Sprint Test in Professional Soccer Players.

The objective was to analyze the changes in the horizontal force-velocity profile (HFVP) during the execution of repeated sprinting. Methods: Seventeen first-division Chilean soccer players completed a repeated sprint protocol consisting of eight sprints of 30 m with 25-s pauses between repetitions. The behavior of HFVP variables in each attempt was recorded from video recordings and analysis in the MySprint® application. Results: Differences (p < 0.05) were found between sprints in the following: time (T), starting from sprint 5 (F = 35.6; η2p = 0.69); theoretical maximum speed (V0), starting from sprint 4 (F = 29.3; η2p = 0.51); maximum power (PM), starting from sprint 5 (F = 17; η2p = 0.52); rate of decrease in force index produced at each step (DRF), starting from sprint 1 (F = 3.20; η2p = 0.17); and RF10, starting from sprint 1 (F = 15.5; η2p = 0.49). In comparison, F0 and RFpeak did not present any differences (p > 0.05). Conclusion: The HFVP variables more sensitive to the effects of fatigue induced by an RSA protocol are those associated with the production of force at high speeds, being V0, DRF, and Pmax, while those that contribute to the generation of force at the beginning of the sprint, F0 and RFpeak, do not present essential variations.

Effects of neuromuscular training on psychomotor development and active joint position sense in school children.

As psychomotor development occurs in a specific social context, the environment in which a child is reared is important. The randomized study involved forty-five school children between 8 and 10 years. They were assigned to a control group (n = 23) and a neuromuscular training group (n = 22). A neuromuscular intervention for six weeks, on two nonconsecutive days, and in a circuit with 30-second stations was performed. The psychomotor development was evaluated through a psychomotor battery and the active joint position sense through the positional error. In the control group, the positional error decreased significantly in the shoulder (p < 0.001) and hip (p < 0.001), while the scores of motor function increased significantly which included balance (p < 0.001), spatio-temporal structuring (p = 0.022), global praxia (p = 0.002), and fine praxia (p = 0.003). In the neuromuscular training group, the positional error decreased significantly in the shoulder (p = 0.015), elbow (p = 0.015), wrist (p < 0.001), hip (p < 0.001), knee (p < 0.001), and ankle (p < 0.001), while the motor function scores increased significantly which included tonicity (p < 0.001), balance (p < 0.001), notion of the body (p < 0.001), spatio-temporal structuring (p < 0.001), global praxia (p < 0.001), and fine praxia (p < 0.001). A six-week neuromuscular training improved active joint position sense and psychomotor development in children.

Expresión génica de mediadores moleculares para potencial terapia celular en el síndrome gastrointestinal inducido por radiación / Genetic expression of molecular mediators for potential cell therapy in radiation-induced gastrointestinal syndrome

Antecedentes: Las células madres intestinales generan las distintas estirpes celulares a dicho nivel. Estas se regulan por interacciones entre el epitelio y las células del nicho celular anexo. Estas se pueden ver dañadas en tratamientos con radiación, generando el síndrome gastrointestinal inducido por radiación. Se ha visto que células madre mesenquimales (MSC) y macrófagos de médula ósea (BMM) tienen propiedades de regeneración tisular. Objetivos: Evaluar la expresión génica de IL-4, Wnt6, VEGF y bFGF, a partir de cultivos celulares primarios independientes de MSC derivadas de tejido adiposo y BMM de ratones C57BL/6, por medio de PCR en tiempo real (qRT-PCR). Diseño experimental: A partir de un análisis in silico, se confeccionaron primers para evaluar la expresión génica de las moléculas propuestas, en los cultivos primarios por medio de qRT-PCR y electroforesis. Resultados y proyecciones: IL-4 y Wnt6 no son expresadas en las muestras de BMM y MSC. VEGF y bFGF son expresadas por diferentes células, dando expresión diferenciada. A futuro, se deben evaluar las mismas estirpes celulares en un ambiente inflamatorio y su efecto en la expresión génica, en especial VEGF y bFGF. Limitaciones: El número de moléculas en estudio es limitado y la expresión se evalúo solo a nivel genético.

Background: Intestinal stem cell generates diferents cellular types in their niche. They're regulated by interactions between epithelium and niche's cells, and can be damaged by medical radiation treatments causing radiation-induced gastrointestinal syndrome. It has seen that mesenchymal stem cells (MSC) d and bone marrow-derived macrophages (BMM) have propierties of tissular regeneration. Objectives: Determinated genetic expression of IL-4, Wnt6, VEGF and bFGF, in primary cellular cultures of MSC derivated of adipose tissue and BMM of C57BL/6 mice, through real time PCR (qRT-PCR). Methods: By an in silico analysis, we created primers to evaluate the proposed molecules in the primary cellular cultives, with qRT-PCR and electrophoresis. Results and projections: IL-4 and Wnt6 were not expressed in the MSC and BMM samples. VEGF and bFGF were expressed by different cells, giving differential expression. In the future, the same samples should be analyzed in an inflammatory environment, especially VEGF and bFGF. Limitations: The number of molecules are limited and the expression of them is only in a genetic level.

The effect of pyrolysis on the chemical, thermal and rheological properties of pitch.

Pitch-based carbon fibers are of considerable interest as high-performance materials. There are reports over the last several decades detailing (i) methods of improving pitch-based carbon fiber performance, and (ii) reducing the cost of production via novel processing techniques. However, there remain considerable challenges in producing high-performance pitch-based carbon fibers consistently on an industrial scale. This is arguably due to the difficulty of scaling the melt-spinning process to compensate for variability in pitch feedstock quality and a lack of understanding of processing-structure-performance relationships. This work focuses on the early stages of heat treatment (pyrolysis) of isotropic pitch and its effect on the chemical, thermal, and rheological properties of the pitch, which help determine its processability. More specifically, we quantify significant changes in chemical structure, Mw, Tg, Ts, and shear and extensional rheology as a function of pyrolysis time at 400 °C. The extensional rheology, in particular, shows that the 'stretchability' of the pitch samples strongly depends on pyrolysis severity, and is important for characterizing 'drawability'. Using a novel analysis of the uniaxial stretching kinematics, we show an isothermal 'drawability window' that allows for the largest axial and radial Hencky strains at constant rate. We hypothesize that this extensional drawability window could facilitate the successful processing of pitch into high quality fiber, minimizing the trial-and-error approach currently used in the field.