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A methodology is proposed to achieve an effective quantification of the element Calcium in soil samples, using a portable X-ray Fluorescence (pXRF) equipment. The protocol began by preparing two ideal matrices using an increasing mass, measured on an analytical balance, of Calcium and Sodium Nitrate as binder. It is the Gravimetric technique. In both samples the fluorescent emission line of the element Calcium was calibrated using an standard reference material 1400 boneash.The validation of ideal samples of the element Calcium using the XRF technique with respect to AAS as an experimental standard, using linear correlation methods, to estimate from statistical inference the real concentration of the analyte, allowed us to appreciate that both approaches remain above the standard curve provided by AAS, with a value of 1.8 and 1.68, respectively. Which means that the tendency to evaluate Calcium samples by XRF are overestimated with respect to the curve provided by AAS. Since the last correlation coefficient is very close to 1.0 and its statistical inference equation is precisely known, the authors of this work propose to apply quantification protocol to real sediment samples. • A methodology is proposed to achieve an effective quantification of the element Calcium in soil samples, using a portable X-ray Fluorescence (pXRF) equipment • The validation of ideal samples of the element Calcium using the XRF technique with respect to AAS as an experimental standard, using linear correlation methods • This work pretend to resolve another weakness by the portable system and is that the number of accounts provided by conventional XRF are not consistent with a% w/w of analyte.

A promising strategy for developing novel therapies against tropical diseases, including malaria, leishmaniasis, and trypanosomiasis, is to detect biological targets such as trypanothione reductase, a vital parasite enzyme that regulates oxidative stress. This enzyme is highly selective and conserved in the Trypanosotidae family and has an ortholog in the Plasmodium genus. Previous studies have established that an isosteric replacement of naphthoquinone's carbonyl group with a sulfone group leads to compounds with high bioactivity and selectivity (half-maximal inhibitory concentration = 3 μM against intracellular amastigotes of L. panamensis, selectivity index = 153 over monocytes U-937). In this study, we analyzed the reactive oxygen species (ROS) levels of parasites through indirect measurements of the tryparedoxin system after treatment with these isosteric compounds. This strategy proved that a significant increase in the ROS levels and strong mitochondrial perturbation led to the death of parasites due to cell homeostatic imbalance, confirming the compounds' effectiveness in disrupting this important metabolic pathway. To improve understanding of the parasite-molecule interaction, 27 new compounds were synthesized and assessed against parasites of the three principal tropical diseases (malaria, leishmaniasis, and trypanosomiasis), displaying an EC50 below 10 μM and good correlation with in-silico studies, indicating that the 4H-thiochromen-4-one 1,1-dioxide core is a special allosteric modulator. It can interact in the binding pocket through key amino acids like Ser-14, Leu-17, Trp-21, Ser-109, Tyr-110, and Met-113, leading to interhelical disruption.

Abstract Background The bacterial genus Exiguobacterium includes several species that inhabit environments with a wide range of temperature, salinity, and pH. This is why the microorganisms from this genus are known generically as polyextremophiles. Several environmental isolates have been explored and characterized for enzyme production as well as for bioremediation purposes. In this line, toxic metal(loid) reduction by these microorganisms represents an approach to decontaminate soluble metal ions via their transformation into less toxic, insoluble derivatives. Microbial-mediated metal(loid) reduction frequently results in the synthesis of nanoscale structures—nanostructures (NS) —. Thus, microorganisms could be used as an ecofriendly way to get NS. Results We analyzed the tolerance of Exiguobacterium acetylicum MF03, E. aurantiacum MF06, and E. profundum MF08 to Silver (I), gold (III), and tellurium (IV) compounds. Specifically, we explored the ability of cell-free extracts from these bacteria to reduce these toxicants and synthesize NS in vitro, both in the presence or absence of oxygen. All isolates exhibited higher tolerance to these toxicants in anaerobiosis. While in the absence of oxygen they showed high tellurite- and silver-reducing activity at pH 9.0, whereas AuCl4 − which was reduced at pH 7.0 in both conditions. Given these results, cell-free extracts were used to synthesize NS containing silver, gold or tellurium, characterizing their size, morphology and chemical composition. Silver and tellurium NS exhibited smaller size under anaerobiosis and their morphology was circular (silver NS), starred (tellurium NS) or amorphous (gold NS). Conclusions This nanostructure-synthesizing ability makes these isolates interesting candidates to get NS with biotechnological potential.

The paper tries to develop the role that the feeling of fundamentality plays in Zubiri. This feeling is expressed in diverse attitudes towards the problem of God (theism, atheism, etc.). We propose that the feeling allows, in part, to direct the creation of diverse possibilities of realization through value judgments. It directs, to a certain extent, the search for these diverse attitudes. On the other hand, it allows for the experience of the sketches of these attitudes. For instance, the negative experience of a determined conception of God is conditioned not only by intellective aspects, but also sentimental ones. We give some examples of this out of some philosophers’ lives.

Herein we report the use of an environmental multimetal(loid)-resistant strain, MF05, to biosynthesize single- or multi-element nanostructures under anaerobic conditions. Inorganic nanostructure synthesis typically requires methodologies and conditions that are harsh and environmentally hazardous. Thus, green/eco-friendly procedures are desirable, where the use of microorganisms and their extracts as bionanofactories is a reliable strategy. First, MF05 was entirely sequenced and identified as an Escherichia coli-related strain with some genetic differences from the traditional BW25113. Secondly, we compared the CdS nanostructure biosynthesis by whole-cell in a design defined minimal culture medium containing sulfite as the only sulfur source to obtain sulfide reduction from a low-cost chalcogen reactant. Under anaerobic conditions, this process was greatly favored, and irregular CdS (ex. 370 nm; em. 520-530 nm) was obtained. When other chalcogenites were tested (selenite and tellurite), only spherical Se0 and elongated Te0 nanostructures were observed by TEM and analyzed by SEM-EDX. In addition, enzymatic-mediated chalcogenite (sulfite, selenite, and tellurite) reduction was assessed by using MF05 crude extracts in anaerobiosis; similar results for nanostructures were obtained; however Se0 and Te0 formation were more regular in shape and cleaner (with less background). Finally, the in vitro nanostructure biosynthesis was assessed with salts of Ag, Au, Cd, and Li alone or in combination with chalcogenites. Several single or binary nanostructures were detected. Our results showed that MF05 is a versatile anaerobic bionanofactory for different types of inorganic NS. synthesis.

This paper attempts to show how Zubiri was understanding and explaining his «proof» or argument for the existence of God from his last works. We study his proof through the «way of religation» from four texts or seminars: The theological problem of man: God, religion, Christianity (1971), The unfolding of the problem of God (1971-1973, published as a second part in Man and God), The theological problem of man: man and God (1973) and Sentient Intelligence (1980-1983).

Se propone una aproximación al realismo científico desde la perspectiva de Zubiri, para quien, por un lado, la realidad es el modo "de suyo" en que se actualizan los contenidos "en" la aprehensión y, por otro lado, la verdad es la misma realidad en cuanto que "actualizada". Como la realidad ya se da en la aprehensión, no es un logro de la ciencia, mientras lo postulado solo puede ser erróneo en un proceso de verificación. En la medida en que el error es posible por la verdad, los fracasos de la ciencia, en lugar de ser una prueba a favor del antirrealismo, son un indicio que apoya al realismo.

The purpose of this study is to identify the main themes of the Pacific Alliances’ development speech. Therefore, a double task will be proposed: from the study of its founding texts, we will determine that this speech is composed by elements belonging to a neoliberal development model, largely adopted at a global level ; then, we will identify the new strategies to revitalize a speech from a model that has obtained mixed results in the Latin-American region, for example, through the promotion of the business spirit and the support of Small and Medium Enterprises.

Microorganism survival in the presence of toxic substances such as metal(loid)s lies chiefly on their ability to resist (or tolerate) such elements through specific resistance mechanisms. Among them, toxicant reduction has attracted the attention of researchers because metal(loid)-reducing bacteria are being used to recover and/or decontaminate polluted sites. Particularly, our interest is to analyze the toxicity of gold and tellurium compounds for the environmental microorganism Enterobacter cloacae MF01 and also to explore the generation of nanostructures to be used in future biotechnological processes. Resistance of E. cloacae MF01 to gold and tellurium salts as well as the putative mechanisms involved -both in aerobic and anaerobic growth conditions- was evaluated. These metal(loid)s were selected because of their potential application in biotechnology. Resistance to auric tetrachloride acid (HAuCl4) and potassium tellurite (K2TeO3) was assessed by determining areas of growth inhibition, minimum inhibitory concentrations, and growth curves as well as by viability tests. E. cloacae MF01 exhibited higher resistance to HAuCl4 and K2TeO3 under aerobic and anaerobic conditions, respectively. In general, their toxicity is mediated by the generation of reactive oxygen species and by a decrease of intracellular reduced thiols (RSH). To assess if resistance implies toxicant reduction, intra- and extra-cellular toxicant-reducing activities were evaluated. While E. cloacae MF01 exhibited intra- and extra-cellular HAuCl4-reducing activity, tellurite reduction was observed only intracellularly. Then, Au- and Te-containing nanostructures (AuNS and TeNS, respectively) were synthesized using crude extracts from E. cloacae MF01 and their size, morphology, and chemical composition was evaluated.

In continuation of our efforts to identify promising antileishmanial agents based on the chroman scaffold, we synthesized several substituted 2H-thiochroman derivatives, including thiochromenes, thichromanones and hydrazones substituted in C-2 or C-3 with carbonyl or carboxyl groups. Thirty-two compounds were thus obtained, characterized, and evaluated against intracellular amastigotes of Leishmania (V) panamensis. Twelve compounds were active, with EC50 values lower than 40 µM, but only four compounds displayed the highest antileishmanial activity, with EC50 values below 10 µM; these all compounds possess a good Selectivity Index > 2.6. Although two active compounds were thiochromenes, a clear structure-activity relationship was not detected since each active compound has a different substitution pattern.

Microbes are suitable candidates to recover and decontaminate different environments from soluble metal ions, either via reduction or precipitation to generate insoluble, non-toxic derivatives. In general, microorganisms reduce toxic metal ions generating nanostructures (NS), which display great applicability in biotechnological processes. Since the molecular bases of bacterial reduction are still unknown, the search for new -environmentally safe and less expensive- methods to synthesize NS have made biological systems attractive candidates. Here, 47 microorganisms isolated from a number of environmental samples were analyzed for their tolerance or sensitivity to 19 metal(loid)s. Ten of them were highly tolerant to some of them and were assessed for their ability to reduce these toxicants in vitro. All isolates were analyzed by 16S rRNA gene sequencing, fatty acids composition, biochemical tests and electron microscopy. Results showed that they belong to the Enterobacter, Staphylococcus, Acinetobacter, and Exiguobacterium genera. Most strains displayed metal(loid)-reducing activity using either NADH or NADPH as cofactor. While Acinetobacter schindleri showed the highest tellurite (TeO32-) and tetrachloro aurate (AuCl4-) reducing activity, Staphylococcus sciuri and Exiguobacterium acetylicum exhibited selenite (SeO32-) and silver (Ag+) reducing activity, respectively. Based on these results, we used these bacteria to synthetize, in vivo and in vitro Te, Se, Au, and Ag-containing nanostructures. On the other hand, we also used purified E. cloacae glutathione reductase to synthesize in vitro Te-, Ag-, and Se-containing NS, whose morphology, size, composition, and chemical composition were evaluated. Finally, we assessed the putative anti-bacterial activity exhibited by the in vitro synthesized NS: Te-containing NS were more effective than Au-NS in inhibiting Escherichia coli and Listeria monocytogenes growth. Aerobically synthesized TeNS using MF09 crude extracts showed MICs of 45- and 66- μg/ml for E. coli and L. monocytogenes, respectively. Similar MIC values (40 and 82 μg/ml, respectively) were observed for TeNS generated using crude extracts from gorA-overexpressing E. coli. In turn, AuNS MICs for E. coli and L. monocytogenes were 64- and 68- μg/ml, respectively.

In this paper we try to show Zubiri’s concept of species as an essential moment of the individual and how this concept is in contrast to other species concepts present in the current debate, for example, species understood as class, population and historical individual. We propose that this essentialist concept of species is not incompatible with the current idea of evolution.

This paper attempts to clarify what constitutes «the problem of God» as a philosophical problem with Xavier Zubiri. To do this, we divide the paper into three parts. First, we should clarify if possible to study «philosophically» the subject of «God». From Zubiri, this is possible if we study the «problem» of God as something «given» sentiently, not «God» understood as a supreme being beyond the world. Second, we have to analyze what is the «problem of God» according to Zubiri. Do we mean that the problem of God is «given» as a starting point in the primordial apprehension? Or might it be that the «problem of God» is something that can lead or not «towards» God? Finally, thirdly, we must analyze the various attitudes and solutions to the «problem of God» as atheism, agnosticism or theism. Zubiri defended himself a theistic position and established a rational proof that was gradually modified in his later years.

En este trabajo intentamos mostrar el esquema central por el cual presentó Zubiri su concepción de la vida desde sus primeros cursos extrauniversitarios hasta Inteligencia sentiente. Este esquema presenta la vida en tres estratos intrínsecamente relacionados llamados «suscitación-modificacióntónica-respuesta», «habitud-respecto formal» y «estructura de la vida». Estos estratos están ordenados desde el más superficial al más profundo en el orden de la fundamentación. Además, Zubiri presenta una idea unitaria radical de la vida que califica como «autoposesión». Es su idea de la vida como modo de realidad que, de alguna manera, nos dice lo esencial de los tres estratos antes mencionados. Por otra parte, en el trabajo intentamos repensar todo este esquema de la vida desde su gran obra llamada Inteligencia sentiente. Apoyándonos en ella, sostenemos que el orden de fundamentación debe ser invertido. Lo que se presentaba como más radical es ahora lo menos accesible a un análisis de meros hechos obtenidos desde la aprehensión humana.

In this study, a versatile synthesis of silver nanoparticles of well-defined size by using hydrogels as a template and stabilizer of nanoparticle size is reported. The prepared hydrogels are based on polyvinyl alcohol and maleic acid as crosslinker agents. Three hydrogels with the same nature were synthesized, however, the crosslinking degree was varied. The silver nanoparticles were synthesized into each prepared hydrogel matrix achieving three significant, different-sized nanoparticles that were spherical in shape with a narrow size distribution. It is likely that the polymer network stabilized the nanoparticles. It was determined that the hydrogel network structure can control the size and shape of the nanoparticles. The hydrogel/silver nanohybrids were characterized by swelling degree, Thermal Gravimetric Analysis (TGA), Fourier Transform Infrared (FT-IR), Scanning Electron Microscopy (SEM) and Transmission Electron Microscope (TEM). Antibacterial activity against Staphylococcus aureus was evaluated, confirming antimicrobial action of the encapsulated silver nanoparticles into the hydrogels.

Solanum nudum Dunal steroids have been reported as being antimalarial compounds; however, their concentration in plants is low, meaning that the species could be threatened by over-harvesting for this purpose. Swern oxidation was used for hemisynthesis of diosgenone (one of the most active steroidal sapogenin diosgenin compounds). Eighteen structural analogues were prepared; three of them were found to be more active than diosgenone (IC50 27.9 μM vs. 10.1 μM, 2.9 μM and 11.3 μM). The presence of a 4-en-3-one grouping in the A-ring of the compounds seems to be indispensable for antiplasmodial activity; progesterone (having the same functional group in the steroid A-ring) has also displayed antiplasmodial activity. Quantitative correlations between molecular structure and bioactivity were thus explored in diosgenone and several derivatives using well-established 3D-QSAR techniques. The models showed that combining electrostatic (70%) and steric (30%) fields can explain most variance regarding compound activity. Malarial parasitemia in mice became reduced by oral administration of two diosgenone derivatives.

En este escrito se intenta explicar qué es ciencia en Zubiri. Aunque Zubiri no dejó un libro específico sobre ciencia, intentamos meditar este tema siguiendo el análisis en tres momentos de la aprehensión de realidad que hace Zubiri en su libro Inteligencia sentiente. A partir de allí, proponemos que el concepto de ciencia debe analizarse en estos tres momentos, el primero de los cuales muestra que el conocimiento científico hunde sus raíces en la realidad aprehendida sentientemente. La ciencia suele pensarse como una actividad racional. Esto sin duda es verdad. Pero la racionalidad es insuficiente para entender todo el quehacer científico. Se ha pensado la ciencia también desde los aspectos sociales e históricos. Esto también es verdad. Pero todo el conocimiento científico arranca de los sentidos, pero entendidos desde el momento de formalidad de realidad más que desde el momento de contenido, como hace el empirismo.

En este trabajo intentamos meditar la concepción de tiempo en la teoría de sucesión ecológica de Margalef. En un modelo clásico de sucesión ecológica, las poblaciones se suceden unas a otras. Cada fase de esa sucesión “en tanto fase temporal” está meramente yuxtapuesta a las demás fases. Es el tiempo cronométrico, el tiempo como “medida” del reloj. El tiempo es aquí algo absoluto, independiente del proceso como en Newton. Esto no ocurre en el modelo de Margalef. Él piensa el ecosistema como un proceso de transferencia de energía y acumulación de información. Por esto, en el proceso dinámico del ecosistema existen diversas fases determinadas por la dinámica intrínseca del sistema. Cada ecosistema posee así su tiempo propio.

Cutaneous leishmaniasis (CL) is a neglected tropical disease, which causes severe skin lesions. Due to the lack of effective vaccines, and toxicity or reduced effectiveness of available drugs in addition to complex and prolonged treatments, there is an urgent need to develop alternatives for the treatment for CL with different mechanisms of action. In our effort to search for new promising hits against Leishmania parasites we prepared 18 acyl hydrazone derivatives of thiochroman-4-ones. Compounds were evaluated for their in vitro antileishmanial activity against the intracellular amastigote form of Leishmania panamensis and cytotoxic activity against human monocytes (U-937 ATCC CRL-1593.2). Our results show that derivatization of the thiochroman-4-ones with acyl hydrazones significantly enhances the antileishmanial activity. Among the compounds tested semicarbazone and thiosemicarbazone derivatives of thioflavanone 19 and 20 displayed the highest antileishmanial activities, with EC50 values of 5.4 and 5.1 µM and low cytotoxicities (100.2 and 50.1 µM respectively), resulting in higher indexes of selectivity (IS).

The S-containing heterocyclic compounds benzothiopyrans or thiochromones stand out as having promising biological activities due to their structural relationship with chromones (benzopyrans), which are widely known as privileged scaffolds in medicinal chemistry. In this work, we report the synthesis of 35 thiochromone derivatives and the in vitro antileishmanial and cytotoxic activities. Compounds were tested against intracellular amastigotes of Leishmania panamensis and cytotoxic activity against human monocytes (U-937 ATCC CRL-1593.2). Compounds bearing a vinyl sulfone moiety, 4h, 4i, 4j, 4k, 4l and 4m, displayed the highest antileishmanial activity, with EC50 values lower than 10 μM and an index of selectivity over 100 for compounds 4j and 4l. When the double bond or the sulfone moiety was removed, the activity decreased. Our results show that thiochromones bearing a vinyl sulfone moiety are endowed with high antileishmanial activity and low cytotoxicity.

En este trabajo intentamos meditar si es posible concebir la edad como un tiempo propio de los seres vivos incluyendo al hombre. En el trabajo revisamos diversos conceptos de edad obtenidos de diversas ciencias biológicas como la cronobiología, la gerontología, la biología evolutiva y la biología del desarrollo descubriendo que en ellas, en general, se sigue pensando el tiempo biológico como el tiempo que mide un reloj. Nosotros proponemos que la edad como tiempo biológico debe ser entendida como una fase del proceso biológico, pero en función del ciclo completo del organismo. En el caso del ser humano, su edad está determinada también por lo que se “espera” de él. Su edad está determinada entonces por aspectos biológicos y culturales.

El presente artículo indaga en el pensamiento del último Zubiri, esto es, llamado noología, y desde la trilogía de la inteligencia: Inteligencia sentiente (1980-1983) y del escrito El concepto de materia, la articulación entre realidad y actualidad como soporte conceptual para comprender una filosofía del cuerpo humano que integre, por una parte, la filosofía zubiriana a lo largo de su obra y, por otra parte, que nos posibilite entender al hombre en su radical unidad corporal constitutiva tanto en el cosmos como en el mundo.