Crystal structure of the N-benzyloxycarbonyl-Alanyl-Phenylalanyl-methyl ester: the importance of the H-bonding pattern

Large crystals of the methyl ester of the N-a-benzyloxycarbonyl protected Ala-Phe dipeptide (Z-AF-OMe) were obtained after the very slow evaporation of a solution of the corresponding carboxylic acid (Z-AF-OH) in methanol containing an excess of HCl. The structure was confirmed by single crystal X-ray diffraction data. It crystallizes in the orthorhombic space group P212121 with unit cell dimensions a = 5.0655(6) Å, b = 8.4614(8) Å, c = 46.856(5) Å, V = 2008.3(4) Å3, Z = 4. In the crystal, the molecules form hydrogen bonded chains running along the a axis of the unit cell. Other secondary interactions are also discussed

Compositional uniformity, domain patterning and the mechanism underlying nano-chessboard arrays

We propose that systems exhibiting compositional patterning at the nanoscale, so far assumed to be due to some kind of ordered phase segregation, can be understood instead in terms of coherent, single phase ordering of minority motifs, caused by some constrained drive for uniformity. The essential features of this type of arrangements can be reproduced using a superspace construction typical of uniformity-driven orderings, which only requires the knowledge of the modulation vectors observed in the diffraction patterns. The idea is discussed in terms of a simple two dimensional lattice-gas model that simulates a binary system in which the dilution of the minority component is favored. This simple model already exhibits a hierarchy of arrangements similar to the experimentally observed nano-chessboard and nano-diamond patterns, which are described as occupational modulated structures with two independent modulation wave vectors and simple step-like occupation modulation functions.Comment: Preprint. 11 pages, 11 figure

Cooperative Education in Green Chemistry: The Spanish Experience

A common postgraduate training in Green Chemistry is currently being carried out by several Spanish universities. This initiative considers the corresponding Máster and PhD programs in Sustainable Chemistry and has been successfully achieved with the participation of experts from different Universities and Research Institutions grouped within the coverage of the Spanish Network on Sustainable Chemistry (REDQS). A cooperative effort and a modular design are the key elements that have allowed maintaining the Spanish Interuniversity Máster and PhD programs for more than a decade, providing a high level of quality and a unique possibility, for many students, of being trained at an advanced level in Green Chemistry

OK, boomer : new users, different platforms, new challenges

The popularization of new interaction spaces brings new narratives and social phenomena that merit attention from the scientific community. Based on the existing literature on the new challenges facing the communication discipline with these emerging narratives, this editorial summarizes the empirical and theoretical contributions of the thematic issue entitled "New Narratives for New Consumers: Influencers and the Millennial and Centennial Generations." The authors emphasize that the studies selected for this thematic issue explore the innovative features and opportunities of the emerging scenarios and offer a cautionary account of their structural problems and the urgency of a new media literacy

Macrocycle Synthesis by Chloride-Templated Amide Bond Formation

A new family of pseudopeptidic macrocyclic compounds has been prepared involving an anion-templated amide bond formation reaction at the macrocyclization step. Chloride anion was found to be the most efficient template in the macrocyclization process, producing improved macrocyclization yields with regard to the nontemplated reaction. The data suggest a kinetic effect of the chloride template, providing an appropriate folded conformation of the openchain precursor and reducing the energy barrier for the formation of the macrocyclic product.This work was supported by the Spanish Ministry of Science and Innovation (CTQ2012-38543-C03) and Generalitat Valenciana (PROMETEO/2012/020). V.M.-C. thanks Generalitat Valenciana for a postdoctoral fellowship (APOSTD/ 2013/041)

Kinetic Analysis for Macrocyclizations Involving Anionic Template at the Transition State

Several kinetic models for the macrocyclization of a C2 pseudopeptide with a dihalide through a SN2 reaction have been developed. These models not only focus on the kinetic analysis of the main macrocyclization reaction, but also consider the competitive oligomerization/polymerization processes yielding undesired oligomeric/polymeric byproducts. The effect of anions has also been included in the kinetic models, as they can act as catalytic templates in the transition state reducing and stabilizing the transition state. The corresponding differential equation systems for each kinetic model can be solved numerically. Through a comprehensive analysis of these results, it is possible to obtain a better understanding of the different parameters that are involved in the macrocyclization reaction mechanism and to develop strategies for the optimization of the desired processes

A continuum theory for mineral solid solutions undergoing chemo-mechanical processes

Recent studies on metamorphic petrology as well as microstructural observations suggest the influence of mechanical effects upon chemically active metamorphic minerals. Thus, the understanding of such a coupling is crucial to describe the dynamics of geomaterials. In this effort, we derive a thermodynamically-consistent framework to characterize the evolution of chemically active minerals. We model the metamorphic mineral assemblages as a solid-species solution where the species mass transport and chemical reaction drive the stress generation process. The theoretical foundations of the framework rely on modern continuum mechanics, thermodynamics far from equilibrium, and the phase-field model. We treat the mineral solid solution as a continuum body, and following the Larch\'e and Cahn network model, we define displacement and strain fields. Consequently, we obtain a set of coupled chemo-mechanical equations. We use the aforementioned framework to study single minerals as solid solutions during metamorphism. Furthermore, we emphasise the use of the phase-field framework as a promising tool to model complex multi-physics processes in geoscience. Without loss of generality, we use common physical and chemical parameters found in the geoscience literature to portrait a comprehensive view of the underlying physics. Thereby, we carry out 2D and 3D numerical simulations using material parameters for metamorphic minerals to showcase and verify the chemo-mechanical interactions of mineral solid solutions that undergo spinodal decomposition, chemical reactions, and deformation

Chiral catalysts immobilized on achiral polymers: effect of the polymer support on the performance of the catalyst

Positive effects of the polymeric support on the performance of supported chiral catalysts, in terms of activity, stability and selectivity–enantioselectivity, have been reported when the support is properly selected and optimized opening the way to the design of more efficient catalytic systems

A continuum theory for mineral solid solutions undergoing chemo-mechanical processes

Recent studies on metamorphic petrology as well as microstructural observations suggest the influence of mechanical effects upon chemically active metamorphic minerals. Thus, the understanding of such a coupling is crucial to describe the dynamics of geomaterials. In this effort, we derive a thermodynamically consistent framework to characterize the evolution of chemically active minerals. We model the metamorphic mineral assemblages as a solid-species solution where the species mass transport and chemical reaction drive the stress generation process. The theoretical foundations of the framework rely on modern continuum mechanics, thermodynamics far from equilibrium, and the phase-field model. We treat the mineral solid solution as a continuum body, and following the Larché and Cahn network model, we define displacement and strain fields. Consequently, we obtain a set of coupled chemo-mechanical equations. We use the aforementioned framework to study single minerals as solid solutions during metamorphism. Furthermore, we emphasise the use of the phase-field framework as a promising tool to model complex multi-physics processes in geoscience. Without loss of generality, we use common physical and chemical parameters found in the geoscience literature to portrait a comprehensive view of the underlying physics. Thereby, we carry out 2D and 3D numerical simulations using material parameters for mineral solid solutions to showcase and verify the chemo-mechanical interactions of mineral solid solutions that undergo spinodal decomposition, chemical reactions, and deformation.journal articl

Teacher reactions to the use of blogs in the classroom.

En este artículo presentamos un estudio exploratorio cualitativo cuyo objetivo fue co - no cer la percepción que una muestra de 25 profesores de enseñanza primaria, secundaria y uni versitaria, que utilizan habitualmente los blogs en sus aulas, sobre las posibilidades edu cativas que, en su opinión, tiene este recurso en rendimiento y comportamiento de los alum nos. Se realizó una investigación cualitativa mediante la técnica de relatos. La extracción de la información contenida en los relatos fue llevada a cabo mediante Análisis de Con - tin gencias utilizando software experimental como GestMagister y GOLUCA, para elaborar una representación gráfica en forma de Red Asociativas Pathfinder de las categorías más im portantes encontradas. Según estas categorías y sus relaciones identificamos las princi pa les posibilidades educativas del uso de los blogs, en opinión de los participantes.In this article we present a cualitative study whose objective was to find out the perception of 25 teachers of primary, high school and university who usually use blogs for their lessons, regarding the educational posibilities which, in their opionions, this resource has in the performance and behaviour of the pupils. A qualitative investigation was made using the story telling technique. The extraction of information of the tales was made using Risk Analysis, helped by experimental software, in the form of GestMagister and GOLUCA, to make a graphical representation in the shape of an Pathfinder Asociative Network of the most important categories found. With these categories and their relations we identify the main educational posibilities of the use of blogs in the opinion of the participants.peerReviewe