Solvent-Free Enantioselective Friedländer Condensation with Wet 1,1′-Binaphthalene-2,2′-diamine-Derived Prolinamides as Organocatalysts

Wet unsupported and supported 1,1′-binaphthalene-2,2′-diamine (BINAM) derived prolinamides are efficient organocatalysts under solvent-free conditions at room temperature to perform the synthesis of chiral tacrine analogues in good yields (up to 93%) and excellent enantioselectivies (up to 96%). The Friedländer reaction involved in this process takes place with several cyclohexanone derivatives and 2-aminoaromatic aldehydes, and it is compatible with the presence of either electron-withdrawing or electron-donating groups at the aromatic ring of the 2-aminoaryl aldehyde derivatives used as electrophiles. The reaction can be extended to cyclopentanone derivatives, affording a regioisomeric but separable mixture of products. The use of the wet silica gel supported organocatalyst, under solvent-free conditions, for this process led to the expected product (up to 87% enantiomeric excess), with its reuse being possible at least up to five times.

Synthesis of Nitrogenated Heterocycles by Asymmetric Transfer Hydrogenation of N-(tert-Butylsulfinyl)haloimines

Highly optically enriched, protected, nitrogenated heterocycles with different ring sizes have been synthesized by a very efficient methodology consisting of the asymmetric transfer hydrogenation of N-(tert-butylsulfinyl)haloimines followed by treatment with a base to promote an intramolecular nucleophilic substitution process. N-Protected aziridines, pyrrolidines, piperidines, and azepanes bearing aromatic, heteroaromatic, and aliphatic substituents have been obtained in very high yields and diastereomeric ratios up to >99:1. The free heterocycles can be easily obtained by a simple and mild desulfinylation procedure. Both enantiomers of the free heterocycles can be prepared with the same good results by changing the absolute configuration of the sulfur atom of the sulfinyl group.

Electrocatalytic Performance of SiO2-SWCNT Nanocomposites Prepared by Electroassisted Deposition

Composite materials made of porous SiO2 matrices filled with single-walled carbon nanotubes (SWCNTs) were deposited on electrodes by an electroassisted deposition method. The synthesized materials were characterized by several techniques, showing that porous silica prevents the aggregation of SWCNT on the electrodes, as could be observed by transmission electron microscopy and Raman spectroscopy. Different redox probes were employed to test their electrochemical sensing properties. The silica layer allows the permeation of the redox probes to the electrode surface and improves the electrochemical reversibility indicating an electrocatalytic effect by the incorporation of dispersed SWCNT into the silica films.

Flexible ruthenium oxide-activated carbon cloth composites prepared by simple electrodeposition methods

This work focuses on the preparation of flexible ruthenium oxide containing activated carbon cloth by electrodeposition. Different electrodeposition methods have been used, including chronoamperometry, chronopotentiometry and cyclic voltammetry. The electrochemical properties of the obtained materials have been measured. The results show that the potentiostatic method allows preparing composites with higher specific capacitance than the pristine activated carbon cloth. The capacitance values measured by cyclic voltammetry at 10 mV s−1 and 1 V of potential window were up to 160 and 180 F g−1. This means an improvement of 82% and 100% with respect to the capacitance of the pristine activated carbon cloth. This excellent capacitance enhancement is attributed to the small particle size (4–5 nm) and the three-dimensional nanoporous network of the ruthenium oxide film which allows reaching very high degree of oxide utilization without blocking the pore structure of the activated carbon cloth. In addition, the electrodes maintain the mechanical properties of the carbon cloth and can be useful for flexible devices.

Electrochemical generation of oxygen-containing groups in an ordered microporous zeolite-templated carbon

Zeolite templated carbon (ZTC) was electrochemically oxidized under various conditions, and its chemistry and structural evolution were compared to those produced by conventional chemical oxidation. In both oxidation methods, a general loss of the original structure regularity and high surface area was observed with increasing amount of oxidation. However, the electrochemical method showed much better controllability and enabled the generation of a large number of oxygen functional groups while retaining the original structure of the ZTC. Unlike chemical treatments, highly microporous carbons with an ordered 3-D structure, high surface area (ranging between 1900 and 3500 m2/g) and a large number of oxygen groups (O = 11,000–3300 μmol/g), have been prepared by the electrochemical method. Some insights into the electrooxidation mechanism of carbon materials are proposed from the obtained polarization curves, using ZTC as a model carbon material.

Tailoring the porosity of chemically activated hydrothermal carbons: Influence of the precursor and hydrothermal carbonization temperature

Advanced porous materials with tailored porosity (extremely high development of microporosity together with a narrow micropore size distribution (MPSD)) are required in energy and environmental related applications. Lignocellulosic biomass derived HTC carbons are good precursors for the synthesis of activated carbons (ACs) via KOH chemical activation. However, more research is needed in order to tailor the microporosity for those specific applications. In the present work, the influence of the precursor and HTC temperature on the porous properties of the resulting ACs is analyzed, remarking that, regardless of the precursor, highly microporous ACs could be generated. The HTC temperature was found to be an extremely influential parameter affecting the porosity development and the MPSD of the ACs. Tuning of the MPSD of the ACs was achieved by modification of the HTC temperature. Promising preliminary results in gas storage (i.e. CO2 capture and high pressure CH4 storage) were obtained with these materials, showing the effectiveness of this synthesis strategy in converting a low value lignocellulosic biomass into a functional carbon material with high performance in gas storage applications.

Nitrate reduction at Pt(1 0 0) single crystals and preferentially oriented nanoparticles in neutral media

The electroreduction of nitrate on Pt(1 0 0) electrodes in phosphate buffer neutral solution, pH 7.2, is reported. The sensitivity of the reaction to the crystallographic order of the surface is studied through the controlled introduction of defects by using stepped surfaces with (1 0 0) terraces of different length separated by monoatomic steps, either with (1 1 1) or (1 1 0) symmetry. The results of this study show that nitrate reduction occurs mainly on the well defined (1 0 0) terraces in the potential region where H adsorption starts to decrease, allowing the nitrate anion to access the surface. Adsorbed NO has been detected as a stable intermediate in this media. An oxidation process observed at 0.8 V has been identified as leading to the formation of adsorbed NO and being responsible for a secondary reduction process observed in the subsequent negative scan. Using in situ FTIRS, ammonium was found to be the main product of nitrate reduction. This species can be oxidized at high potentials resulting in adsorbed NO and nitrate (probably with nitrite as intermediate).

Size-Dependent and Step-Modulated Supramolecular Electrochemical Properties of Catechol-Derived Adlayers at Pt(hkl) Surfaces

The electrochemical reactivity of catechol-derived adlayers is reported at platinum (Pt) single-crystal electrodes. Pt(111) and stepped vicinal surfaces are used as model surfaces possessing well-ordered nanometer-sized Pt(111) terraces ranging from 0.4 to 12 nm. The electrochemical experiments were designed to probe how the control of monatomic step-density and of atomic-level step structure can be used to modulate molecule–molecule interactions during self-assembly of aromatic-derived organic monolayers at metallic single-crystal electrode surfaces. A hard sphere model of surfaces and a simplified band formation model are used as a theoretical framework for interpretation of experimental results. The experimental results reveal (i) that supramolecular electrochemical effects may be confined, propagated, or modulated by the choice of atomic level crystallographic features (i.e.monatomic steps), deliberately introduced at metallic substrate surfaces, suggesting (ii) that substrate-defect engineering may be used to tune the macroscopic electronic properties of aromatic molecular adlayers and of smaller molecular aggregates.

Alleviation of Zn toxicity by low water availability

Heavy metal contamination and drought are expected to increase in large areas worldwide. However, their combined effect on plant performance has been scantly analyzed. This study examines the effect of Zn supply at different water availabilities on morpho-physiological traits of Quercus suber L. in order to analyze the combined effects of both stresses. Seedlings were treated with four levels of zinc from 3 to 150 µM and exposed to low watering (LW) or high watering (HW) frequency in hydroponic culture, using a growth chamber. Under both watering regimes, Zn concentration in leaves and roots increased with Zn increment in nutrient solution. Nevertheless, at the highest Zn doses, Zn tissue concentrations were almost twice in HW than in LW seedlings. Functional traits as leaf photosynthetic rate and root hydraulic conductivity, and morphological traits as root length and root biomass decreased significantly in response to Zn supply. Auxin levels increased with Zn concentrations, suggesting the involvement of this phytohormone in the seedling response to this element. LW seedlings exposed to 150 µM Zn showed higher root length and root biomass than HW seedlings exposed to the same Zn dose. Our results suggest that low water availability could mitigate Zn toxicity by limiting internal accumulation. Morphological traits involved in the response to both stresses probably contributed to this response.

The role of nutrients for improving seedling quality in drylands

Forest plantations have been extensively used to combat desertification. In drylands, harsh climate conditions and unfertile soils often preclude seedling establishment. The improvement in seedling quality by manipulating nutrient availability could contribute to increase planting success. However, morpho-functional traits defining optimum seedling quality in drylands, and the fertilization schemes to achieve them, are still under discussion. Several studies suggest that well fertilized seedlings may perform better than nutrient limited seedlings in these environments. However, recent works have shown opposite results. In this review, we discuss the concept of seedling quality in drylands based on an evaluation of the effects of nutrient manipulation on seedling morpho-functional traits and field performance. According to existing data, we hypothesize that nutrient-limited small seedlings may be better adapted to arid environments and unfavorable microsites, where access to water is uncertain and a conservative water use strategy may be advantageous. In contrast, in dry sub-humid areas, areas with deep soils, protected from excess radiation, and areas where irrigation is feasible, well-fertilized big seedlings with high root growth potential may have more chances of success. We discuss this theory in the context of the multiple objectives of dryland restoration and the environmental constrains posed by these areas, and identify knowledge gaps that should be targeted to test our hypothesis.

Género y profesión en la evolución histórica de la Enfermería Comunitaria en España

El ámbito comunitario y de salud pública es probablemente el contexto donde las enfermeras han logrado mayores cotas de autonomía profesional y donde su contribución ha sido valorada en mayor medida. No obstante, todavía persisten grandes obstáculos para el pleno desarrollo, algunos de ellos vinculados a la variable género. Por ello, resulta relevante analizar, para el caso español, los antecedentes históricos de esta situación, en la medida que puede ayudar a entender muchos de los problemas y deficiencias que sigue mostrando la Enfermería Comunitaria en la actualidad. Las enfermeras comunitarias contribuyeron al desarrollo de la salud pública en la España contemporánea, proceso que se inició en los años 1920 y que culminó durante la Segunda República, pero el periodo franquista supuso un importante freno al proceso de profesionalización. A través del ejemplo del conflicto público entre enfermeras visitadoras y practicantes, que se gestó en la Segunda República, y se prolongó durante todo el periodo franquista, se analiza cómo el discurso de género estuvo presente, entre otros condicionantes, en la evolución de la Enfermería española y cómo ha venido contribuyendo, hasta nuestros días, en la estructuración de las competencias, y la distribución de responsabilidades y poder.

Environment and health with respect to a poverty-related disease: the epidemiology of trachoma in Spain, 1925-1941

Trachoma currently represents one of the three main causes of ‘avoidable' blindness and reaches intolerable dimensions in many developing countries. It was endemic in many regions of eastern Spain until well into the twentieth century. The aim of this paper is to analyze the epidemiological development of this disease in contemporary Spain; to examine its determining factors, particularly environmental and sanitary/health factors, and, finally, to study the health care, environmental and socio-economic measures that led to its control and eradication. We believe that the historical approach not only highlights the role of environmental factors in the development of trachoma, but may also aid in understanding the current epidemiology of trachoma.

KOH activation of carbon materials obtained from the pyrolysis of ethylene tar at different temperatures

A complete study of the importance of the pyrolysis temperature (up to 1500 °C) of a petroleum residue (ethylene tar) in the activation with KOH of the resultant pyrolysis products (covering from the own ethylene tar to pitches and well developed cokes) has been carried out. The trend in the porosity found for activated carbons is as follows: the pore volume increases with the pyrolysis temperature reaching a maximum value (1.39 cm3/g) at about 460 °C, just at the transition temperature between a fluid pitch and a solid coke. It is the pitch with highest mesophase content that develops the maximum porosity when activated with KOH. The amount of H2, CO and CO2 produced during the reaction of the mesophase pitch and coke with KOH has been quantified, and a trend as described for the pore volume was found with the pyrolysis temperature. Therefore, there is a relationship between the reactivity of the precursor with KOH and the porosity developed by the activated carbon. Since the reactions that produce H2 initiate at temperatures as low as 300 °C, it seems that KOH is modifying the conditions under which the pyrolysis occurs, and this fact is critical in the development of porosity.

High-Resolution N2 Adsorption Isotherms at 77.4 K: Critical Effect of the He Used During Calibration

Accurate characterization of the microporous structure in porous solids is of paramount importance for several applications such as energy and gas storage, nanoconfinement reactions, and so on. Among the different techniques for precise textural characterization, high-precision gas adsorption measurement of probe molecules at cryogenic temperatures (e.g., N2 at 77.4 K and Ar at 87.3 K) is the most widely used, after appropriate calibration of the sample holder with a probe gas, which does not experience physisorption processes. Although traditionally helium has been considered not to be adsorbed in porous solids at cryogenic temperatures, here we show that even at 77.4 K (high above its boiling temperature, 4 K) the use of He in the calibration step can give rise to erroneous interpretations when narrow micropores/constrictions are present.

Use of Costas arrays in subpixel metrology

Subpixel methods increase the accuracy and efficiency of image detectors, processing units, and algorithms and provide very cost-effective systems for object tracking. A recently proposed method permits micropixel and submicropixel accuracies providing certain design constraints on the target are met. In this paper, we explore the use of Costas arrays - permutation matrices with ideal auto-ambiguity properties - for the design of such targets.