96 research outputs found
Halogenation of pyridinium-N-(2'-pyridyl)aminide: an easy synthesis of halo-2-aminopyridines
The regioselective halogenatmn of pyrldmium-N-(2’-pyridyljaminide 1 with N-chloro,\ud
bromo or iodosuccinimtde under mild conditions IS described. The method, combined with a\ud
reductmn of the N-N bond, allows an easy preparation of 5-h& and 3,5-dihalo-Z-aminopyridines 4The authors wish to thank the Comisión Interministerial de Ciencia y Tecnología (C.I.C.Y.T.) for financial support (Project PB90-0284) and to Lilly S. A. for one studentship (C.B.
An easy preparation of pyridinium N-heteroarylaminides
A synthesis of substituted pyridinium N-heteroarylaminides, e.g., I, is reported. Heteroaryl chlorides underwent nucleophilic substitution with N-aminopyridinium iodide to give the corresponding substituted pyridinium N-heteroarylaminides in good yields. [on SciFinder(R)]Differently substituted pyridinium N-heteroarylaminides have been prepared in one step with good yield from N-aminopyridinium iodide and the corresponding heteroaryl chloride.The authors wish to thank the Ministerio de Ciencia y Tecnología (projects CICYT-2FD97-1248 and BQU2001-1508) for financial support, and the Ministerio de Educación y Cultura for a studenship (M.J.R.)
Manejo ortodóncico-periodontal de recesión gingival
Restaurar la posición dentaria y la salud periodontal es esencial en ortodoncia y periodoncia. Los objetivos de este artículo fueron evaluar un caso clínico mediante el análisis de la relación de los movimientos dentales y las recesiones gingivales, determinar el momento oportuno para la realización de la cirugía mucogingival y nombrar las posibles etiologías del movimiento dental indeseado a causa de un retenedor fijo. Presentamos un informe de 30 meses de seguimiento de una paciente, cuya queja principal fue sobre un cambio progresivo en la posición dental asociado con una recesión gingival, a pesar de un retenedor fijo de un tratamiento ortodóncico previo. Se indicó retratamiento de ortodoncia y cirugía periodontal para cubrir el defecto por recesión. Luego del tratamiento, se concluyó que los movimientos dentales pueden desencadenar, agravar o mejorar las recesiones gingivales, por lo que es importante una evaluación previa individual. El momento de la cirugía mucogingival depende de la dirección del movimiento, los tejidos circundantes y el fenotipo periodontal del paciente
Impacto del nivel de conocimientos, la fuente de información y la experiencia con la enfermedad sobre las actitudes, creencias, conocimientos y emociones asociadas a la diabetes en un grupo de estudiantes de educación secundaria
El presente estudio se diseñó con el objetivo de conocer los conocimientos, creencias, actitudes y emociones asociados a la diabetes en un grupo de jóvenes sanos con distinto grado de experiencia con la enfermedad. Participaron en el estudio 600 alumnos de 4º de ESO de nueve centros educativos seleccionados al azar durante un curso académico. Los participantes tenían edades comprendidas entre los 15 y 18 años (M= 15.62, dt= 0.70; 50.8% mujeres). Se administró en aplicaciones colectivas el Cuestionario sobre Diabetes (CSD; Vázquez y Cruz, 2004), diseñado para este estudio con el fin de evaluar en adolescentes dichas variables. Los participantes mostraron tener algún conocimiento, aunque no exhaustivo, sobre la enfermedad, y en general unas creencias y actitudes
positivas hacia la misma, así como cierta emocionalidad ante el hecho de padecerla. La fuente de información, la experiencia con la enfermedad y el nivel de conocimientos tuvieron una influencia importante sobre las actitudes, creencias y emociones asociadas a esta enfermedad. Estos resultados deben tenerse en cuenta debido al impacto que estas
variables pueden ejercer sobre las conductas preventivas y terapéuticas de las personas sanas y los propios pacientes, así como en las conductas de apoyo a éstos.The present study was designed to establish the knowledge, beliefs, attitudes and emotions associated with diabetes in a healthy, young sample with different experience with the illness. Six hundreds of students of 4th grade of secondary obligatory education took part in the study. They were recruited from nine educative centres randomly selected during an academic year. The age of the participants ranged from 15 to 18 years old (M = 15.62, sd = 0.70; 50.8 % women). The Cuestionario sobre Diabetes (CSD; Vázquez and Cruz, 2004) was administered in collective applications. This questionnaire was designed for this study in order to evaluate in adolescents the above mentioned variables. The participants showed some level of knowledge regarding the illness, although it was not exhaustive, and, in general, they showed positive beliefs and attitudes towards the disease, as well as certain emocionality regarding the fact of suffering from it. The source of information, the experience with the illness and the level of knowledge of the participants exerted a relevant influence on the attitudes, beliefs and emotions associated with this illness. These results must be taken into account due to the impact that these variables can exert on the preventive and therapeutic behaviors of healthy persons and patients, as well as on the supporting behaviors aimed to ill people
The first example of an intramolecular westphal reaction. Synthesis of a new aza-quinolizinium type system
The first example of an intramolecular Westphal condensation is described. To test the utility of this reaction, new benz(f)azino[2,1-a]phthalazinium salts have been prepared from appropriate dicarbonyl precursors.The authors wish to thank the Comisión Interministerial de Ciencia y Tecnología (C.I.C.Y.T.) (Project SAF98-0093) for financial support and one studentship (V. M. B.
Pyridinium N-(2'-azinyl)aminides: Regioselective synthesis of 2-alkylaminoazines
The regioselective alkylation of pyridinium-N-(2'-azinil)aminides with alkyl halides under mild conditions is described. The alkylation, combined with a reduction of the N-N bond, allows an easy preparation of 2-alkylaminoazines.The authors wish to thank the Comision Interministerial de Ciencia y Tecnologı́a (C.I.C.Y.T.) (Project PM97-0074) and the Vicerrectorado de Investigación, Universidad de Alcalá for financial support (Project E014/97)
Impacto del gobierno corporativo en el sector de supermercados e hipermercados en Colombia
El efecto de la globalización sobre las economías nacionales y los casos de fraude
financiero presentados en algunas organizaciones, abrió la puerta a estudios relacionados con
el funcionamiento y gobierno de una organización, no sólo porque la gestión y la confianza
que se deposita en sus administradores son importantes, sino también porque el buen
funcionamiento de los mercados depende de esto. Por esta razón, la información adecuada
sobre las organizaciones no sólo contribuye a minimizar el riesgo de las inversiones, sino que
también reduce las asimetrías. De esta forma, aumenta la transparencia de la gestión y el
rendimiento (Alonso, 2007).
El objetivo principal de esta investigación es analizar el impacto de las prácticas de
gobierno corporativo sobre la creación de valor a través del análisis de indicadores financieros
en el sector de supermercados e hipermercados en Colombia. De esta manera se buscará el
posible impacto de la implementación de prácticas de gobierno corporativo sobre la creación
de valor financiero en el sector de supermercados e hipermercados en Colombia.
Esta tesis corresponde a un estudio cualitativo descriptivo, utilizando fuentes
secundarias como instrumentos de investigación, entre informes financieros anuales y de
gobierno corporativo publicados, y según dependa, las empresas como fuente principal. Se
seleccionó una muestra de tres empresas del sector y se seleccionó el análisis del año 2015.
También, se presenta el análisis de la información recolectada, con la cual se realiza un
análisis adicional de las variables del estudio; sin embargo, esta tesis no pretende generalizar
los resultados debido a la limitación en el logro de la información. Se explica el tema
detallado de gobierno corporativo y el análisis de los indicadores financieros ROE, ROA,
indicadores de margen EBITDA y de Margen de Utilidad Neta. Finalmente, como resultado
de esta investigación, no es posible concluir un impacto de las prácticas de gobierno
corporativo y la generación de valor para el sector de supermercados e hipermercados en
ColombiaThe globalization effect on the national economies and cases of financial fraud
presented in some organizations opened the door to studies related to the functioning and
governance of an organization; not only because the management and the trust that is
deposited in its administrators is important, also because the proper functioning of markets
depends on this. For this reason, adequate information about organizations or companies not
only contributes with minimizing risk on investments, also reduces asymmetries. In this way,
transparency of management and performance increases (Alonso, 2007).
The principal objective of this research is to relate the practices of corporate
governance and the value creation through the analysis of the financial indicators analysis in
the companies of supermarkets and hypermarkets sector in Colombia. In this way, it would
be sought the possible impact between the implementation of corporate governance practices
and the financial value creation in the supermarkets and hypermarkets sector in Colombia.
This thesis corresponds to a qualitative and descriptive study, it uses secondary
sources as research instruments, such as the annual reports and corporate governance reports
published, and in the case for one of the companies a principal source. A sample of three
companies of supermarkets and hypermarkets sector in Colombia, and the analysis of the
2015 were selected. It also presents the analysis of the information collected, with which an
extensive further analysis of the study variables is performed; however, this thesis is not
intended to generalize the results because of the limitation in the achievement of the
information. It explains the detailed topic of Corporate Governance and the analysis of the
financial indicators ROE, ROA, EBITDA margin indicator and Net Profit Margin Indicator.
Finally, as of result of this investigation, it is not possible to conclude among the
corporate governance practices and the generation of financial value for the supermarkets and
hypermarkets sector in ColombiaTesi
Carbon redistribution by erosion processes in an intensively disturbed catchment
29 Pags.- 6 Tabls.- 6 Figs. This article belongs to a special issue of Catena titled
"Geoecology in Mediterranean mountain areas. Tribute to Professor José María García Ruiz". The definitive version is available at: http://www.sciencedirect.com/science/journal/03418162Understanding how organic carbon (OC) moves with sediments along the fluvial system is crucial to determining catchment scale carbon budgets and helps the proper management of fragile ecosystems. Especially challenging is the analysis of OC dynamics during fluvial transport in heterogeneous, fragile, and disturbed environments with ephemeral and intense hydrological pulses, typical of Mediterranean conditions. This paper explores the catchment scale OC redistribution by lateral flows in extreme Mediterranean environmental conditions, from a geomorphological perspective. The study area is a catchment (Cárcavo) in SE Spain with a semiarid climate, erodible lithologies, and shallow soils, which is highly disturbed by agricultural terraces, land levelling, reforestation, and construction of check-dams. To increase our understanding of catchment scale OC redistribution induced by erosion, we studied in detail the subcatchments of eight check-dams distributed along the catchments main channel. We determined 137Cs, physicochemical characteristics, and the OC pools of the catchment soils and sediments deposited behind each check-dam, performed spatial analysis of catchment properties and buffer areas around the check-dams, and carried out geomorphological analysis of the slope-channel connections.
The soils showed very low total organic carbon (TOC) values, oscillating between 15.2 and 4.4 g kg− 1 for forest and agricultural soils, respectively. Sediments mobilized by erosion were poor in TOC (6.6 ± 0.7 g kg– 1) compared to the eroded (forest) soils, and the redistribution of OC through the catchment, especially of the mineral associated organic carbon (MAC) pool, showed the same pattern as clay particles and 137Cs. The TOC erosion rates estimated for the Cárcavo watershed are relatively low (0.031 ± 0.03 Mg ha− 1 y− 1) but similar to those reported for subhumid Mediterranean catchments that are less fragile and more conducive to plant growth. The TOC erosion/total erosion ratio was lower (0.06%) than other estimates, although the average OC concentration of the sediments was higher than that of the agricultural soils of the catchment, underlining the problem of maintaining sustainable soil OC contents.
The OC in deposited sediments came not only from surface erosion processes, but also from deeper soil or sediment layers mobilized by concentrated erosion processes. Sediment richer in OC came from the surface soil of vegetated (reforested) areas close and well connected to the channels. Subcatchments dominated by laminar erosion processes showed a TOC erosion/total erosion ratio that was two times higher than that of subcatchments dominated by concentrated flow erosion processes. The lithology, soils, and geomorphology exert a more important control on OC redistribution than land use and vegetation cover in this geomorphologically very active catchment.This work was financially supported by the projects ADAPT (CGL2013-42009-R) and DISECO (CGL2014-55-405-R) from the Spanish Government, National Plan of Science; the project CAMBIO (18933/JLI/13) of the Seneca Foundation, Regional Government of Murcia (Spain); and the project SOGLO (P7/24 IAP BELSPO) from the Belgian Government. Joris de Vente was supported by a ‘Ramón y Cajal’ grant (RYC-2012-10375).Peer reviewe
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