X-Ray and Spectroscopic Investigation of Some Strontium and Zinc Substituted Calcium Fluoroapatites

Simultaneous strontium and zinc substitution for calcium in the fluoroapatite lattice was investigated. Crystallographic data for different members of the series Ca10-x-ySrxZny(PO4)6F2 were obtained from X-ray powder diagrams. The effects of the substitutional process on the strength of the phosphate P-O-bonds were checked by Raman spectroscopy. For comparative purposes, the first members of the series Sr10-xZnx(PO4)6F2 were also investigated in a similar way.Publicado on line en 2014.Facultad de Ciencias Exacta

Preparation and Spectroscopic Characterization of Sn2PO4Br

The synthesis of a new Sn(II) phosphate halogenide, Sn2PO4Br, is described. The com pound was characterized by means of infrared and Raman spectroscopies as well as by its 119Sn-Mößbauer spectrum. The results are compared with those of other Sn2PO4X species.Publicado on line en 2014.Centro de Química Inorgánic

Impacto del conglomerado urbano gran San Miguel de Tucumán sobre la calidad de las aguas del Río Salí

A fin de evaluar la incidencia del área urbana-industrial Gran San Miguel de Tucumán (GSMT) sobre la composición química de las aguas del río Salí, se analizaron las modificaciones producidas en el contenido de indicadores de contaminación a medida que el río atraviesa la zona de estudio. El ion cloruro se considera un buen indicador, ya que no se encuentra afectado por procesos biológicos ni de descomposición, y se asocia con actividades de origen antrópico. Para la interpretación de los resultados se consideraron además otras variables, tales como sólidos (totales, volátiles y suspendidos), materia orgánica y oxígeno disuelto. Se seleccionaron tres puntos de muestreo a lo largo del cauce del río Salí en el tramo correspondiente a su paso por el GSMT. Como referencia de la calidad de las aguas sin alteración se eligió un punto de muestreo ubicado en el balneario El Boyero, próximo a la naciente del río. Se utilizaron datos históricos correspondientes a un seguimiento mensual realizado entre junio de 1998 y junio de 1999 y datos actualizados a noviembre de 2002. Sobre la base del aumento de la masa de cloruro, se encuentra que el GSMT altera la calidad de las aguas del río Salí particularmente en el período de sequía donde la carga se duplica con respecto a la del período húmedo. Estos resultados reflejan una importante diferencia estacional y establecen un umbral por encima del cual se pueden esperar situaciones de mayor aporte a la alteración de la calidad de las aguas. El incremento del contenido de cloruro observado en las cuencas media y baja del río está relacionado principalmente con el lavado de suelos y el escurrimiento superficial.Pollution indicators have been used to assess the influence of the Gran San Miguel de Tucumán (GSMT) urban site on the chemical composition of the Salí River. Because of its conservative character, chloride is an excellent indicator that is associated with human activities. Other variables such as solids, organic matter and dissolved oxygen have also been analyzed. Three sampling stations located along the Salí River, up and downstream of the GSMT were selected. Samples collected in El Boyero, close to the Salí River headwater, represent pristine conditions. Monthly chemical data obtained in the period June 1998 and June 1999 and data from November 2002 were used in the analysis. The increase in the chloride mass observed downstream of the GSMT reflects the alteration of the water quality produced by the city, which in the dry season, is more than twice the load estimated for the humid period. The increase in the chloride contents observed in the central and lower basin is mainly associated with soil lixiviation and runoff. ABSTRACT Pollution indicators have been used to assess the influence of the Gran San Miguel de Tucumán (GSMT) urban site on the chemical composition of the Salí River. Because of its conservative character, chloride is an excellent indicator that is associated with human activities. Other variables such as solids, organic matter and dissolved oxygen have also been analyzed. Three sampling stations located along the Salí River, up and downstream of the GSMT were selected. Samples collected in El Boyero, close to the Salí River headwater, represent pristine conditions. Monthly chemical data obtained in the period June 1998 and June 1999 and data from November 2002 were used in the analysis. The increase in the chloride mass observed downstream of the GSMT reflects the alteration of the water quality produced by the city, which in the dry season, is more than twice the load estimated for the humid period. The increase in the chloride contents observed in the central and lower basin is mainly associated with soil lixiviation and runoff.Fil: Hidalgo, Margarita del Valle. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina. Provincia de Tucumán. Dirección General de Saneamiento Ambiental; ArgentinaFil: García, María G.. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Galindo, María Célides. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Perondi, María E.. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Vece, María B.. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Apella, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Blesa, Miguel Angel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentin

Lubrication and load-bearing properties of human salivary pellicles adsorbed ex vivo on molecularly smooth substrata

In a series of Surface Force Balance experiments, material from human whole saliva was adsorbed to molecularly smooth mica substrata (to form an 'adsorbed salivary film'). Measurements were taken of normal (load bearing, Fn) and shear (frictional, Fs*) forces between two interacting surfaces. One investigation involved a salivary film formed by overnight adsorption from undiluted, centrifuged saliva, with the adsorbed film rinsed with pure water before measurement. Measurements were taken under pure water and 70 mM NaNO3. In a second investigation, a film was formed from and measured under a solution of 7% filtered saliva in 10 mM NaNO3. Fn results for both systems showed purely repulsive layers, with an uncompressed thickness of 35-70 nm for the diluted saliva investigation and, prior to the application of shear, 11 nm for the rinsed system. Fs* was essentially proportional to Fn for all systems and independent of shear speed (in the range 100-2000 nm s-1), with coefficients of friction μ ~ 0.24 and μ ~ 0.46 for the unrinsed and rinsed systems, respectively. All properties of the rinsed system remained similar when the pure water measurement environment was changed to 70 mM NaNO3. For all systems studied, shear gave rise to an approximately threefold increase in the range of normal forces, attributed to the ploughing up of adsorbed material during shear to form debris that stood proud of the adsorbed layer. The results provide a microscopic demonstration of the wear process for a salivary film under shear and may be of particular interest for understanding the implications for in vivo oral lubrication under conditions such as rinsing of the mouth cavity. The work is interpreted in light of earlier studies that showed a structural collapse and increase in friction for an adsorbed salivary film in an environment of low ionic strength

Detecting and correcting publication bias in meta-analysis

textPublication bias (PB) makes the resources for meta-analysis (M-A) unreliable in the sense of completion and accuracy, so to investigate, identify and correct PB is a very important issue in M-A. The current study proposed an empirical comparison in both detection and correcting PB, using a Monte Carlo study. Conditions to be manipulated include the number of primary studies, number of missing studies and true effect size. RANNOR in SAS will be used to generate normally distributed random variables and, for each condition, 10,000 M-As will be simulated. Type I error rates are to be calculated for the conditions with no PB and powers were estimated for the conditions with PB and adequate type I error control. Finally, a demonstration of how M-A can and should be used as a part of program evaluations was given.Educational Psycholog

Uracilato and 5-halouracilato complexes of Cu(II), Zn(II) and Ni(II). X-ray structures of [Cu(uracilato-N1)2(NH3)2]·2(H2O), [Cu(5-chlorouracilato- N1)2(NH3)2](H2O)2, [Ni(5-chlorouracilato-N1)2(en) 2]·2H2O and [Zn(5-chlorouracilato-N1)(NH3)3]·(5-chlorouracilato-N 1)·(H2O)

Four new complexes of uracilato and 5-halouracilato with the divalent metal ions Cu(II), Zn(II) and Ni(II) were obtained and structurally characterized. [Cu(uracilato- N1)2(NH3) 2]·2(H2O) (1) and [Cu(5-chlorouracilato-N 1)2(NH3)2](H2O) 2 (2) complexes present distorted square planar co-ordination geometry around the metal ion. Although an additional axial water molecule is present [Cu(II)-OH2=2.89 Å (for 1) and 2.52 Å (for 2)] in both cases, only in the complex 2 would be considered in the limit of a bond distance. The Zn(II) in [Zn(5-chlorouracilato-N1)(NH 3)3]·(5-chlorouracilato-N1) ·(H2O) presents a tetrahedral co-ordination with three ammonia molecules and the N1 of the corresponding uracilato moiety. A non-coordinated uracilato molecule is present as a counterion and a recognition between co-ordinated and free ligands, by means a tandem of H-bonds, should be mentioned. Finally, the complex [Ni(5-chlorouracilato-N 1)2(en)2] (H2O)2 (where en is ethylenediamine) presents a typical octahedral trans co-ordination with additional hydrogen bonds between 5-chlorouracilato and the NH2 groups of ethylenediamine units.Fil: Terrón, A.. Universidad de las Islas Baleares; EspañaFil: García Raso, A.. Universidad de las Islas Baleares; EspañaFil: Fiol, Juan J.. Universidad de las Islas Baleares; EspañaFil: Amengual, S.. Universidad de las Islas Baleares; EspañaFil: Barceló Oliver, M.. Universidad de las Islas Baleares; EspañaFil: Tótaro, Roxana María. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Apella, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Molins, E.. Universitat Autònoma de Barcelona; EspañaFil: Mata, I.. Universitat Autònoma de Barcelona; Españ