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SARS-CoV-2, the virus causing COVID-19, initiates cell invasion by deploying a receptor binding domain (RBD) to recognize the host transmembrane peptidase angiotensin-converting enzyme 2 (ACE2). Numerous experimental and theoretical studies have adopted high-throughput and structure-guided approaches to (i) understand how the RBD recognizes ACE2, (ii) rationalize, and (iii) predict the effect of viral mutations on the binding affinity. Here, we investigate the allosteric signal triggered by the dissociation of the ACE2-RBD complex. To this end, we construct an Elastic Network Model (ENM), and we use the Structural Perturbation Method (SPM). Our key result is that complex dissociation opens the ACE2 substrate-binding cleft located away from the interface and that fluctuations of the ACE2 binding cleft are facilitated by RBD binding. These and other observations provide a structural and dynamical basis for the influence of SARS-CoV-2 on ACE2 enzymatic activity. In addition, we identify a conserved glycine (G502 in SARS-CoV-2) as a key participant in complex disassembly. [ABSTRACT FROM AUTHOR]

The objective of this study was to analyze the effects of job stability on the motivation of employees of the District Directorate 13D01 Portoviejo Manabí MTOP. The research presented a mixed descriptive, field and documentary design and used a survey applied to a sample of 72 employees. The results indicated that the lack of job stability has a direct impact on work motivation, causing the following effects: frustration, decreased productivity, increased absenteeism and high personnel turnover. In conclusion, it is necessary to improve the institution's stability policies and introduce motivation programs. [ABSTRACT FROM AUTHOR]

Edible vegetable oils are sources of polyunsaturated fatty acids, necessary for a balanced diet capable of providing elements that act on the energetic, structural, and hormonal composition of humans. The growing consumption of these foods has encouraged the search for techniques capable of characterizing their compositions and transformations when subjected to industrial processes or during domestic use. We propose to analyze the transformations undergone by edible vegetable oils originating from different plants due to thermal oxidation. For this, dynamic viscosity, oxidative stability index, fatty acid profile, and infrared spectra determined before and after being subjected to thermal oxidation. The results from infrared spectroscopy were improved through Principal Component Analysis (PCA). Among other results, it was possible to establish correlations between the FTIR spectra, dynamic viscosity, and the profile of fatty acids, allowing the prediction of the concentration of polyunsaturated fatty acids (PUFA) after thermal oxidation by measuring the spectrum of samples before the thermal oxidation process. Furthermore, it is observed that the dynamic viscosity is strongly altered by thermal oxidation, which is directly related to the decrease in PUFA content. The results obtained can be used to predict quality factors of edible vegetable oils, helping to choose the right type of oil for each industrial or domestic process. Practical Applications: This research holds significant practical implications, particularly in detecting adulteration and fraud of edible vegetable oils. The developed method uses physicochemical properties and infrared spectroscopy with principal component analysis to characterize oils and to determine the oil stability index. [ABSTRACT FROM AUTHOR]

Commented text reference: Pirozelli, Paulo. Thomas Kuhn’s Philosophy of Language. Trans/Form/Ação: revista de filosofia da Unesp, vol. 43, Número Especial, p. 345-372, 2020.

Objective To evaluate the early stages of the setting process of chemically activated restorative glass-ionomer cements (GICs). Material and methods Five GICs were evaluated (n = 5): Equia Forte (GC), Equia Forte HT (GC), Ketac Universal (3M ESPE), Maxxion R (FGM) and Riva Self Cure (SDI) by Thermography, Fourier Transform Infrared Attenuated Total Reflectance Spectroscopy (FTIR-ATR) and Gillmore needle indentation mechanical testing. The FTIR-ATR spectra showed the formation of metal carboxylates within the cements and enabled the stabilization time (ST) to be determined and the thermographic camera measured the temperature field images in the sample. Data were statistically analyzed by ANOVA and Tukey–Kramer (α = 5%). Results The Gillmore needle test showed that the order of hardening was opposite to the order of ST values determined by FTIR. The results with the thermographic camera showed two stages of temperature variation, which coincided with the evolution of specific infrared bands. The exception was Maxxion R, which showed only a single step change in temperature. Conclusion The early stages of the GIC setting reaction show temperature changes, both endothermic and exothermic, at specific times, confirming the occurrence of individual chemical reactions. The early setting involves reactions other than carboxylate formation. Significance: This study gives further detail of the early stages of the setting of GICs, and past research regarding the setting reaction of GIC.

Francesca Giordano,1 Giuseppina Daniela Naimo,1 Alessandra Nigro,1 Francesco Romeo,2 Alessandro Paolì,1 Francesca De Amicis,1 Adele Vivacqua,1 Catia Morelli,1 Loredana Mauro,1 Maria Luisa Panno1 1Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Cosenza 87036, Italy; 2Pathologic Anatomy Unit, Annunziata Hospital, Cosenza, ItalyCorrespondence: Maria Luisa PannoDepartment of Pharmacy and Health and Nutrition Sciences, University of Calabria, Rende, Cosenza 87036, ItalyTel +39 984 492927Email mamissina@yahoo.itPurpose: Neuroendocrine differentiation of prostate cancer, induced by androgen deprivation therapy, is mainly related to advanced disease and poor clinical outcome. Genetic and epigenetic alterations are the key elements of the prostate carcinogenesis. A group of compounds able to induce changes in this sense is inhibitors of histone deacetylase, to which it belongs valproic acid (VPA). In the present paper, we evaluated the role of this molecule on the neuroendocrine differentiation of LNCaP cells together with the effect on proliferation and survival signals.Methods: Cell growth was analyzed by MTT and flow cytometry, while expression of proteins through Western blot analysis.Results: Our results have documented that VPA in LNCaP cells reduces cell proliferation, decreases the S phase and Cyclin A, and up-regulates the cyclin-dependent kinase inhibitors p21waf and p27. The acquisition of androgen-independent condition is consistent with an induction of β-III Tubulin and gamma Enolase, both markers of neuroendocrine phenotype. However, all these features cease with the removal of valproate from the culture medium, demonstrating the transitory nature of the epigenetic event. The VPA treatment does not compromise the survival phosphorylated signals of Akt, ERK1/2 and mTOR/p70S6K that remain up-regulated. Consistently, there is an increase of phospho-FOXO3a, to which corresponds the decreased expression of the corresponding oncosuppressor protein.Conclusion: Overall, our findings indicate that VPA in LNCaP prostate tumor cells, although it reduces cell proliferation, is able to drive neuroendocrine phenotype and to maintain the survival of these cells. Keeping in mind that neuroendocrine differentiation of prostate cancer appears to be associated with a poor prognosis, it is necessary to develop new treatments that do not induce neurodifferentiation but able to counteract cell survival.Keywords: prostate cancer, cell proliferation, cell cycle, neuroendocrine tumor

En este trabajo se efectúa la caracterización de los minerales portadores de hierro en arcillas de la llanura costera del estuario del Río de la Plata, incluidas en la Facies Villa Elisa de la Formación Las Escobas (MIS1), con el principal objetivo de contribuir a su interpretación paleoambiental. Además, los resultados permi­ ten hacer inferencias que se estiman de interés para la Pedología y para las Ciencias Ambientales. El trabajo abarca el uso de diversas técnicas (análisis quí­ micos, determinación de propiedades magnéticas, análisis térmico diferencial­ termogravimétrico, difractometría de rayos X y espectroscopia Mössbauer). Los materiales analizados presentan tonalidades gris­oliva y se clasifican como arcillas. Presentan una asociación mineralógica compleja, resultado de la combinación de múltiples factores, que incluyen procesos vinculados a su procedencia, al ambiente de depositación y a los efectos de la pedogénesis. Dominan los argilominerales (aproximadamente 60%), representados principalmente por esmectitas, illita y secundariamente por caolinita e interestratificados illita/esmectita con elevado contenido de capas expansivas. Se identificó también la presencia de cuarzo, plagio­ clasas, feldespatos alcalinos y en menor medida calcita y óxi­hidróxidos de hierro. El contenido de hierro total es considerable (alrededor del 10%), con un claro pre­ dominio de Fe3+ sobre el Fe2+ (92% y 8%, respectivamente). Los óxi­hidróxidos de hierro presentes (goethita y eventualmente ferrihidrita) no constituyen los principales portadores de hierro. De esta manera se concluye que el Fe3+ se en­ cuentra principalmente en los argilominerales, en particular en esmectitas ricas en hierro (Fe­esmectitas), del tipo nontronita/Fe­beidellita. La asociación mineral determinada tiene importantes implicancias para la interpretación paleoambiental. Se concluye que un ambiente de marisma recibió argilominerales a partir de la erosión de suelos loéssicos (principalmente esmectitas e illita) y por corrientes mareales (más ricos en esmectitas y caolinita). Mecanismos propios del ambiente depositacional, vinculados a ciclos de humedecimiento­secado con oscilaciones de Eh en un medio levemente alcalino permitieron la incorporación de hierro en la estructura de las esmectitas. Un aspecto a destacar es que estos materiales pre­ sentan colores glei originados por minerales con Fe3+ (Fe­esmectitas y goethita), lo cual contradice el tradicional supuesto en Pedología, que asocia este patrón de color a minerales de Fe2+. Finalmente, se destaca que la elevada participación de Fe­esmectitas en asociación con óxi­hidróxidos de hierro, contribuye a la adsorción de metales pesados y otros contaminantes de la región, dándole a la Facies Villa Elisa un importante valor ambiental.

Dado que los parámetros magnéticos proporcionan información acerca del tipo, abundancia y tamaño de grano de los minerales magnéticos, es posible utilizarlos para la interpretación de procesos sedimentarios y pedogenéticos. El objetivo del presente trabajo es caracterizar la señal magnética de los suelos que se desarrollan a partir del loess del Pleistoceno – Holoceno en el centro de la provincia de Buenos Aires, en el sector de Tandilia. El área de estudio ocupa un lugar intermedio entre zonas donde existen estudios de magnetismo ambiental, como el norte y el sur de la provincia de Buenos Aires. Esto permite realizar comparaciones que propenden a la elaboración de un modelo magnético regional para los suelos de la región pampeana. Los perfiles de suelos analizados han sido clasificados como Argiudol típico, Hapludol típico y Hapludol petrocálcico. Los minerales que dominan la señal magnética corresponden en todos los casos a especies ferrimagnéticas, del tipo magnetita-titanomagnetitas-maghemita. Las técnicas empleadas indican dominio de granos magnéticos de diámetro inferior a 1 µm, principalmente Dominio Simple (DS). La concentración de estos minerales en el material parental de los suelos analizados difiere de la del material parental de los suelos de otros sectores de la provincia; es más elevada que la del norte y más baja que la del sur. Posiblemente, este patrón tiene una estrecha vinculación con la procedencia sedimentaria, con mayor cantidad de titanomagnetitas hacia el área fuente, ubicada al sudoeste. Los valores más elevados de susceptibilidad magnética se registran en los horizontes A y B, debido a un enriquecimiento en partículas magnéticas de tamaños de grano ultrafino (SP) a fino (DS) por efecto de la pedogénesis. Los valores de coercitividad de la remanencia disminuyen en dichos horizontes, de manera que la incorporación pedogenética de partículas magnéticas correspondería a especies de baja coercitividad, probablemente maghemita. La señal magnética registrada en los suelos del centro de la provincia de Buenos Aires corresponde al denominado patrón de incremento magnético, semejante al de los suelos del sur dicha provincia, pero inverso al de la mayoría de los suelos del norte. Las diferencias se relacionan con el tiempo de permanencia del agua en el suelo, aspecto vinculado al clima, al relieve y a las características hidráulicas del material.

The well‐known phenomenon of phase separation in synthetic polymers and proteins has become a major topic in biophysics because it has been invoked as a mechanism of compartment formation in cells, without the need for membranes. Most of the coacervates (or condensates) are composed of Intrinsically Disordered Proteins (IDPs) or regions that are structureless, often in interaction with RNA and DNA. One of the more intriguing IDPs is the 526‐residue RNA‐binding protein, Fused in Sarcoma (FUS), whose monomer conformations and condensates exhibit unusual behavior that are sensitive to solution conditions. By focussing principally on the N‐terminus low‐complexity domain (FUS‐LC comprising residues 1–214) and other truncations, we rationalize the findings of solid‐state NMR experiments, which show that FUS‐LC adopts a non‐polymorphic fibril structure (core‐1) involving residues 39–95, flanked by fuzzy coats on both the N‐ and C‐terminal ends. An alternate structure (core‐2), whose free energy is comparable to core‐1, emerges only in the truncated construct (residues 110–214). Both core‐1 and core‐2 fibrils are stabilized by a Tyrosine ladder as well as hydrophilic interactions. The morphologies (gels, fibrils, and glass‐like) adopted by FUS seem to vary greatly, depending on the experimental conditions. The effect of phosphorylation is site‐specific. Simulations show that phosphorylation of residues within the fibril has a greater destabilization effect than residues that are outside the fibril region, which accords well with experiments. Many of the peculiarities associated with FUS may also be shared by other IDPs, such as TDP43 and hnRNPA2. We outline a number of problems for which there is no clear molecular explanation. [ABSTRACT FROM AUTHOR]

Thermal lens spectrometry has been utilized in various applications, and in some application areas, high sensitivity is required. In this work, a mode-mismatched thermal lens configuration probing thermal lens twice was developed for sensitivity enhancement. Experimental results exhibited that doubled sensitivity was achieved with this configuration compared with that attained with a conventional one, which was consistent with the prediction of the theoretical model for thermal lens spectrometry. As a result of the consistency, the linear absorption (attenuation) coefficient of de-ionized water at 532.3 nm was directly measured with this configuration and the conventional one and found to be (4.90 ± 0.05) × 10−2 m−1 and (4.7 ± 0.2) × 10−2 m−1, respectively. The results are in good agreement with accepted literature values. Theoretical analysis revealed that the sensitivity enhancement with this configuration is greater than that by simply doubling the sample thickness in a conventional configuration. [ABSTRACT FROM AUTHOR]

Postpartum depression (PPD) is a mood disorder which can adaptively alter maternal socialisation strategies. Our objective was to investigate differences in ethnotheories and childrearing practices of mothers with low (N = 46) and high (N = 45) intensity of PPD. The Brazilian version of Edinburgh Postnatal Depression Scale was applied at 3, 8 and 36 months. Scales concerning socialisation goals, childrearing beliefs and practices were administered at 36 months. Mothers of both groups did not differ regarding socialisation goals, but they differed concerning childrearing beliefs and practices. High-intensity PPD mothers scored less on interdependent and autonomous beliefs and also on autonomous childrearing practices. Therefore, maternal perceptions about ethnotheories and childrearing practices are ways of cognition which can be modulated by PPD. PPD would affect perceptions about more costly cares that require exclusive attention (autonomous) to further affect perceptions about less costly cares that require shared attention (interdependent).

We investigate dynamics of a class of abstract Timoshenko model with damping and source terms. We obtain a abstract Kirchhoff model as a singular limit of the abstract Timoshenko model when a certain coupling parameter $ a $ tends to infinity. Smooth global attractors with finite fractal dimension and exponential attractors are obtained using the recent quasi-stability theory. We conclude the work comparing the abstract Timoshenko model with abstract Kirchhoff model, in the sense of the upper-semicontinuity of their attractors as $ a $ tends to infinite. [ABSTRACT FROM AUTHOR]

Joseph Agassi is an Israeli scholar born in Jerusalem on May 7, 1927. He has many books and articles published contributing to the fields of logic, scientific method, foundations of sciences, epistemology and, most importantly for this Journal, in the historiography of science. He studied with Karl Popper, who was definitely his biggest influence. He taught around the world in different universities. He currently lives in Herzliya, Israel. For his important contribution to the historiography of science, we chose to open the first issue of this journal with this interview recognizing his importance for the field, as well as paying our homage to him.

The main purpose of this article is to provide a type of general framework of Ludwik Fleck’s reception in Brazil. Although this is not strictly a review of Fleck’s work – what I did in some papers before – we can use some of Fleck’s concepts to understand how his ideas have spread in Brazil. In other words, how was the genesis and development of Fleck’s thought-style in different thought collective in Brazil.