Solid-state NMR and hyperpolarization methods for the Research, Development, and Innovation in Costa Rican science.

Inter and multidisciplinary collaborations are essential to achieve significant improvements in science and technology. Nuclear Magnetic Resonance (NMR) is a versatile technique that permits connecting different scientific disciplines. Therefore, its implementation and extension in several research fields will help to improve Costa Rican Research and Development. This Commentary intends to present the importance of NMR for Costa Rican science, by numbering some solid-state NMR applications that could be useful and attainable for the country, and by highlighting the advances in the use of hyperpolarization methods.

Field-cycling NMR with high-resolution detection under magic-angle spinning: determination of field-window for nuclear hyperpolarization in a photosynthetic reaction center.

Several parameters in NMR depend on the magnetic field strength. Field-cycling NMR is an elegant way to explore the field dependence of these properties. The technique is well developed for solution state and in relaxometry. Here, a shuttle system with magic-angle spinning (MAS) detection is presented to allow for field-dependent studies on solids. The function of this system is demonstrated by exploring the magnetic field dependence of the solid-state photochemically induced nuclear polarization (photo-CIDNP) effect. The effect allows for strong nuclear spin-hyperpolarization in light-induced spin-correlated radical pairs (SCRPs) under solid-state conditions. To this end, 13C MAS NMR is applied to a photosynthetic reaction center (RC) of the purple bacterium Rhodobacter (R.) sphaeroides wildtype (WT). For induction of the effect in the stray field of the magnet and its subsequent observation at 9.4 T under MAS NMR conditions, the sample is shuttled by the use of an aerodynamically driven sample transfer technique. In the RC, we observe the effect down to 0.25 T allowing to determine the window for the occurrence of the effect to be between about 0.2 and 20 T.

Psicología y lógica: Una relación transdisciplinaria / Psychology and logic: A transdisciplinary relation

El presente trabajo constituye una reflexión teórica sobre la vinculación transdisciplinaria entre la Lógica y la Psicología. Como punto de partida se explicitan los tipos de conexión entre disciplinas que caracterizan a las relaciones inter, multi y transdisciplinarias. A continuación,se revisa el psicologismo como un planteamiento en favor de una relación Lógica - Psicología y se presenta al anti-psicologismo como la respuesta a dicho planteamiento. El anti-psicologismo es descrito como un problema para el establecimiento de la relación Psicología - Lógica y por ende se discute la necesidad de eliminar dicho problema antes de esbozar cualquier tipo de relación entre ambas. Se retoman las ideas planteadas por Putnam, Beuchot y Dussel como argumentos para refutar la distinción ser / deber ser entendida como el sustento del anti-psicologismo. Habiendo eliminado el fundamento del anti-psicologismo se posibilita la alteración de la forma en que se discute sobre la relación entre la Lógica y la Psicología a partir de lo cual se presentan, por un lado, con algunos apuntes y ejemplos sobre la forma en que la Lógica puede resolver problemas internos de la Psicología al emplearse herramientas tales como la axiomatización de modelos, el uso de propiedades formales como análogos de funciones psicológicas y el análisis meta-teórico, y por el otro, con la forma en que la Psicología puede proporcionar conocimientos para la construcción de sistemas no-monotónicos de la Lógica y apoyar la didáctica de la Lógica mediante técnicas basadas en la investigación psicológica. El trabajo concluye con algunas ideas que pueden inducir futuros desarrollos de vinculación entre la Lógica y la Psicología.

This paper constitutes a theoretical discussion on the transdisciplinary relationships between Logic and Psychology as a way to give an argument for its legitimacy. This is important because such an enterprise may set the trend to develop better and more explicit ways of dealing with fundamental problems that must be attended in setting up a research project or an applied tool that builds upon a connection between related disciplines. As a starting point three types of connection between disciplines that characterize multi, inter and transdiscipline relations are presented. These relations have specific generate knowledge and develop research methods which distinguish them. The specific relation to whom this paper is directed is the relation between Logic and Psychology. Following this point, psychologism is defined as a point of view in which Logic has its origins or can be reduced to a field of Psychology, as such it is considered as a proposal in favor of a relation between Logic and Psychology and is therefore revisited. Then, anti-psychologism, which stands for a position in which Logic doesn't have its origins or cannot be reduced to Psychology, is presented as the response to psychologism. Anti-psychology and Logic and hence the necessity to eliminate such a problem before the shaping of any kind of a relationship between them is discussed. From there on, the paper builds upon the ideas presented by Putman, Beuchot and Dussel to construct an argument that may refute the is / must be distinction understood as the foundation of anti-psychologism. Such ideas are specifically: (a) The fact that no distinction between is / must be can be drawn because they are both conventionally constructed, (b) the idea that must be values aren't artificial or arbitrary, they have their bases of existence on the nature of the way things are, and (c) that in the description of the nature of things there is a certain value load imbedded in to it. Taken as a whole these ideas show that there is a way to build a balance between values and facts, the is / must be distinction, specifically it is build from the notion that in the empirical description of normality, the general or common way that natural processes occur, a cultural set of values may be inferred, but not in a lineal and asymmetric fashion but more likely as a type of pragmatic-dialectic inference that assigns a balance between the two, giving rise to their conventional and mutually constricted nature. Finally, having eliminated the foundation of anti-psychologism the paper continues to describe what may be seen as a shift in the way the relationship between Logic and Psychology is presented. This is done by transforming the vertical discussion from which a reductionist questions are built to a horizontal one in which such questions are replaced by co-elaboration and communication questions. Near the end, the paper presents some notes and examples on the ways in which Logic can solve some internal problems of Psychology, that is: a Logic of Psychology, such as the building of axiomatic models, the use of formal properties as an analog of psychological functions and in the form of a meta-theoretic analysis. The counterpart of this horizontal relationship is the Psychology of Logic which is exemplified by the way in which Psychology may provide knowledge for the constructions of non-monotonic systems and the development of research based teaching tools for Logic. Finally, the paper ends with some themes which may induce future inquiries on the relation between Logic and Psychology, these are: (a) the legitimacy of other type of relations between Logic and Psychology, mainly on the development of no monotonic models, (b) the avoidance of the danger that Logic may become a mathematical recreation, and (c) to continue with a line of work that Kantor stated in 1945.

DNA-damaging disinfection byproducts: alkylation mechanism of mutagenic mucohalic acids.

Hydroxyhalofuranones form a group of genotoxic disinfection byproduct (DBP) of increasing interest. Among them, mucohalic acids (3,4-dihalo-5-hydroxyfuran-2(5H)-one, MXA) are known mutagens that react with nucleotides, affording etheno, oxaloetheno, and halopropenal derivatives. Mucohalic acids have also found use in organic synthesis due to their high functionalization. In this work, the alkylation kinetics of mucochloric and mucobromic acids with model nucleophiles aniline and NBP has been studied experimentally. Also, the alkylation mechanism of nucleosides by MXA has been studied in silico. The results described allow us to reach the following conclusions: (i) based on the kinetic and computational evidence obtained, a reaction mechanism was proposed, in which MXA react directly with amino groups in nucleotides, preferentially attacking the exocyclic amino groups over the endocyclic aromatic nitrogen atoms; (ii) the suggested mechanism is in agreement with both the product distribution observed experimentally and the mutational pattern of MXA; (iii) the limiting step in the alkylation reaction is addition to the carbonyl group, subsequent steps occurring rapidly; and (iv) mucoxyhalic acids, the hydrolysis products of MXA, play no role in the alkylation reaction by MXA.

Reactivity of p-nitrostyrene oxide as an alkylating agent. A kinetic approach to biomimetic conditions.

The alkylating potential of p-nitrostyrene oxide (pNSO)--a compound used as a substrate to study the activity of epoxide hydrolases as well as in polymer production and in the pharmaceutical industry--was investigated kinetically. The molecule 4-(p-nitrobenzyl)pyridine (NBP), as a model nucleophile for DNA bases, was used as an alkylation substrate. In order to gain insight into the effect of the hydrolysis of pNSO, as well as the hydrolysis of the NBP-pNSO adduct on the pNSO alkylating efficiency, these two competing reactions were studied in parallel with the main NBP-alkylation reaction. The following conclusions were drawn: (i) pNSO reacts through an S(N)2 mechanism, with NBP to form an adduct, pNSO-NBP (AD). The rate equation for the adduct formation is: r = d[AD]/dt = k(alk)[NBP][pNSO]-k(hyd)(AD) [AD] (k(alk), and k(hyd)(AD) being the alkylation rate constant and the NBP-pNSO adduct hydrolysis rate constant, respectively); (ii) the alkylating capacity of pNSO, defined as the fraction of initial alkylating agent that forms the adduct, is similar to that of mutagenic agents as effective as ß-propiolactone. The instability of the pNSO-NBP adduct formed could be invoked to explain the lower mutagenicity shown by pNSO; (iii) the different stabilities of the α and ß-adducts formed between NBP and styrene oxides show that the alkylating capacity f = k(alk)[NBP]/(k(alk)[NBP] + k(hyd)) (k(hyd) being the pNSO hydrolysis rate constant) as well as the alkylating effectiveness, AL = f/k(hyd)(AD), are useful tools for correlating the chemical reactivity and mutagenicity of styrene oxides; (iv) a pNSO-guanosine adduct was detected.

Alkylating potential of α,ß-unsaturated compounds.

Alkylation reactions of the nucleoside guanosine (Guo) by the α,ß-unsaturated compounds (α,ß-UC) acrylonitrile (AN), acrylamide (AM), acrylic acid (AA) and acrolein (AC), which can act as alkylating agents of DNA, were investigated kinetically. The following conclusions were drawn: i) The Guo alkylation mechanism by AC is different from those brought about the other α,ß-UC; ii) for the first three, the following sequence of alkylating potential was found: AN > AM > AA; iii) A correlation between the chemical reactivity (alkylation rate constants) of AN, AM, and AA and their capacity to form adducts with biomarkers was found. iv) Guo alkylation reactions for AN and AM occur through Michael addition mechanisms, reversible in the first case, and irreversible in the second. The equilibrium constant for the formation of the Guo-AN adduct is K(eq) (37 °C) = 5 × 10(-4); v) The low energy barrier (≈10 kJ mol(-1)) to reverse the Guo alkylation by AN reflects the easy reversibility of this reaction and its possible correction by repair mechanisms; vi) No reaction was observed for AN, AM, and AA at pH < 8.0. In contrast, Guo alkylation by AC was observed under cellular pH conditions. The reaction rate constants for the formation of the α-OH-Guo adduct (the most genotoxic isomer), is 1.5-fold faster than that of γ-OH-Guo. vii) a correlation between the chemical reactivity of α,ß-UC (alkylation rate constants) and mutagenicity was found.

Análisis funcional del conocimiento previo: sus efectos sobre el ajuste lector / Functional analysis of prior knowledge: its effects upon reading adjustment / Análise funcional do conhecimento prévio: seus efeitos sobre o ajuste leitor

Se evaluaron los efectos de distintos tipos funcionales de contactos previos con los referentes de un texto (historia de referencialidad e historia situacional efectiva) sobre la ejecución de estudiantes universitarios en una prueba de ajuste lector. Participaron cinco grupos experimentales diferenciados por el tipo de historia de contacto construida mediante un entrenamiento. Cada tipo de historia era progresivamente más complejo: Contextual, Suplementario, Selector, Sustitutivo Referencial y Sustitutivo No Referencial Un sexto grupo (control) no tuvo ningún entrenamiento. Los seis grupos fueron posteriormente expuestos a la prueba de ajuste lector, consistente en preguntas de diferente complejidad funcional. Los resultados revelan una función positiva entre la complejidad de la historia de contacto y el porcentaje total de aciertos en la prueba de ajuste lector (excepto en el grupo con la historia más compleja). Se discuten los resultados enfatizando las funciones disposicionales de los diferentes tipos de historia en el ajuste lector, contrastándolas con la noción tradicional de conocimiento previo.

This study evaluated the effects of different types of previous contacts with the referents of a text (referential history and effective situational history) on the performance of University students on a reading adjustment test. Five experimental groups differentiated from each other by the type of history elaborated on a training session participated in the study. The types of histories were progressively more complex: Contextual, Supplementary, Selective, Referential Substitutive and Non-Referential Substitutive. For subjects in the control group no history was constructed and they were directly administered the reading adjustment test. Results suggest that there is a direct function between the complexity of the contact history and the percentage of total correct responses in the reading adjustment test (except in the group with the most complex history). Results are analysed emphasizing the dispositional functions of different types of history in reading adjustment, as compared with the traditional notion of prior knowledge.

Foram avaliados os efeitos de vários tipos funcionais de contatos prévios mediante os referentes de um texto (historia de referência e historia situacional efetiva) sobre o desempenho de estudantes universitários em uma prova de ajuste leitor. Participaram cinco grupos experimentais diferençados pela classe de história de contato construída depois de um treinamento. Cada classe de história era progressivamente mais complexa: contextual, suplementaria, seletora, substitutiva referencial e substitutiva não referencial. Um sexto grupo não teve treinamento. Posteriormente, aos seis grupos lhes foi aplicada uma prova de ajuste leitor, consistente em perguntas de diferente complexidade funcional. Os resultados indicam uma função positiva entre a complexidade da história de contato e a porcentagem total de acertos na prova de ajuste leitor (salvo no grupo que tenha a história mais complexa). São analisados os resultados enfatizando nas funções disposicionais das diversas classes de história no ajuste leitor, contrastando-as com a noção tradicional de conhecimento prévio.