Electronic structure and reactivity indexes of cobalt clusters, both pure and mixed with NO and [Formula: see text] ([Formula: see text], [Formula: see text] and [Formula: see text]).

Among the most popular motivations for environmental scientists is improving materials that could be useful to fight or avoid pollution. This work shows a study of neutral and cationic cobalt clusters from 4 to 9 atoms ([Formula: see text], q = 0,1 and n = 4-9) to model their separate interaction with contaminant nitric and nitrous oxides. This study is within the framework of the density functional theory in the Kohn-Sham scheme by using BPW91 functional and 6-311G and 6-31G* basis sets to calculate global and local reactivity indexes. The effect of spin multiplicity is also determined. Results on the geometries of pure cobalt clusters agree with previously reported structures. Global minimum energy structures showed a marked preference towards the interaction of nitric and nitrous oxide molecules with cobalt clusters through chemisorptive dissociation, with the dissociation of the corresponding nitrogen oxide. Reactivity indexes reveal an even-odd alternate, which is related to electron counts. Moreover, the chemical potential is lowering after interaction with nitrogen oxides. The Fukui function illustrates the reactive zones with a high probability of chemisorption of more nitrogen oxide molecules.

Implementation of High Dose-rate Brachytherapy for Cervix Cancer in a Low-income Country.

BACKGROUND: The purpose of this study is to detail the implementation of HDR brachytherapy at the only radiotherapy center in Nicaragua. METHODS: Patients are treated with external-beam radiotherapy to 46-50Gy at 2Gy/fraction to the pelvis. A gynecologic examination is performed weekly. Once the cervical os is visualized, brachytherapy is initiated. HDR is delivered in four fractions of 7Gy twice weekly. HDR occurs in two phases: preparation and delivery. Treatment preparation occurs in the procedure room, which includes anesthization, cervical dilation, and brachytherapy applicator placement using fixed-geometry tandem and ring with a rectal blade. The applicator is immobilized and the patient transferred to a stretcher and transported to the treatment delivery room. HDR is performed with the patient on the stretcher to minimize motion. AP and lateral films are taken using portable equipment. Physics staff digitize Point A, rectal point, and bladder point. A standard plan is loaded and approved prescribing 7Gy to Point A. If dose to the rectal or bladder points exceeds the constraint, the applicator is adjusted or vaginal packing is added and films repeated. RESULTS: Nearly 10 years after implementing the HDR program, the center is treating 11-15 women with HDR brachytherapy for cervix cancer daily. Because the procedure is carried out over two separate rooms, patients can be staggered and more treated daily. The rooms turn over every 45 minutes. CONCLUSIONS: HDR brachytherapy for cervix cancer has been successfully established in Nicaragua. Significant challenges remain, and there is a role for developed countries to collaborate.

Reactivity of aluminum cluster anions with ammonia: selective etching of Al11(-) and Al12(-).

Reactivity of aluminum cluster anions toward ammonia was studied via mass spectrometry. Highly selective etching of Al(11)(-) and Al(12)(-) was observed at low concentrations of ammonia. However, at sufficiently high concentrations of ammonia, all other sizes of aluminum cluster anions, except for Al(13)(-), were also observed to deplete. The disappearance of Al(11)(-) and Al(12)(-) was accompanied by concurrent production of Al(11)NH(3)(-) and Al(12)NH(3)(-) species, respectively. Theoretical simulations of the photoelectron spectrum of Al(11)NH(3)(-) showed conclusively that its ammonia moiety is chemisorbed without dissociation, although in the case of Al(12)NH(3)(-), dissociation of the ammonia moiety could not be excluded. Moreover, since differences in calculated Al(n)(-) + NH(3) (n=9-12) reaction energies were not able to explain the observed selective etching of Al(11)(-) and Al(12)(-), we concluded that thermodynamics plays only a minor role in determining the observed reactivity pattern, and that kinetics is the more influential factor. In particular, the conversion from the physisorbed Al(n)(-)(NH(3)) to chemisorbed Al(n)NH(3)(-) species is proposed as the likely rate-limiting step.

Estructura de tallas, selectividad y composición específica de las capturas en trampas para peces marinos en el Golfo de California

Size structure, selectivity and specific composition of the catch in traps for marine fish in the Gulf of California. We analyzed the performance of three traps for marine fish between October 2005 and August 2006 in the Gulf of California, Mexico. The performance was measured as difference in selectivity, fish diversity, size structure and yield. The samples were collected with quadrangular traps 90 cm wide, 120 cm long and 50 cm high. Trap type 1 had a 5 x 5 cm mesh (type 2: 5 x 5 cm including a rear panel of 5 x 10 cm; trap 3: 5 x 10 cm). Most abundant in our traps were: Goldspotted sand bass (Paralabrax auroguttatus), Ocean whitefish (Caulolatilus princeps), Spotted sand bass (P. maculatofaciatus) and Bighead tilefish (C. affinis); there was no bycatch. The number of fish per trap per haul decreased when mesh size was increased. We also observed a direct relationship between mesh size and average fish length. By comparing our traps with the authorized fishing gear (hooks-and-line) we found that the size structure is larger in traps. Traps with larger mesh size were more selective. Consequently, we recommend adding traps to hooks-and-line as authorized fishing gear in the small scale fisheries of the Sonora coast, Mexico. Rev. Biol. Trop. 56 (3): 1403-1417. Epub 2008 September 30.

Se realizó un estudio orientado a evaluar tres tipos de trampas (eficiencia de captura, estructura de tallas, selectividad y composición de especies) para la captura de peces marinos en el Golfo de California. La recolecta de muestras se efectuó con trampas de 90 cm de ancho, 120 cm de largo y 50 cm de alto, con malla galvanizada cuadrangular en tres tamaños: una trampa completamente construida con abertura de malla de 5 x 5 cm (trampa 1); otra con malla de 5 x 5 cm, pero con el panel trasero de 5 x 10 cm (trampa 2) y la tercera con malla de 5 x 10 cm (trampa 3). Los experimentos se llevaron a cabo entre octubre del 2005 y agosto del 2006. Las especies que presentaron mayor incidencia de captura en cuanto a proporción del volumen total fueron el extranjero (Paralabrax auroguttatus), pierna (Caulolatilus princeps), cabrilla arenera (P. maculatofaciatus) y conejo (C. affinis) y prácticamente todas las capturas tuvieron valor comercial. El número de organismos por trampa por lance decreció al aumentar el tamaño de malla, mientras que la talla media se incrementó con el tamaño de malla de las trampas. Además las tallas son más grandes en cualquiera de las trampas que las obtenidas con piola de mano con anzuelos (el arte de pesca autorizado). Los resultados de la selectividad de tallas indicaron que las trampas de malla grande fueron más selectivas que las de malla más pequeña. En consecuencia, la captura con tram-pas es mejor que con los anzuelos y línea de mano, por lo que las trampas serían una muy útil adición al conjunto de artes de pesca usados en la pesca artesanal de la costa de Sonora, México.

[Size structure, selectivity and specific composition of the catch in traps for marine fish in the Gulf of California]. / Estructura de tallas, selectividad y composición específica de las capturas en trampas para peces marinos en el Golfo de California.

We analyzed the performance of three traps for marine fish between October 2005 and August 2006 in the Gulf of California, Mexico. The performance was measured as difference in selectivity, fish diversity, size structure and yield. The samples were collected with quadrangular traps 90 cm wide, 120 cm long and 50 cm high. Trap type 1 had a 5 x 5 cm mesh (type 2: 5 x 5 cm including a rear panel of 5 x 10 cm; trap 3: 5 x 10 cm). Most abundant in our traps were: Goldspotted sand bass (Paralabrax auroguttatus), Ocean whitefish (Caulolatilus princeps), Spotted sand bass (P. maculatofaciatus) and Bighead tilefish (C. affinis); there was no bycatch. The number offish per trap per haul decreased when mesh size was increased. We also observed a direct relationship between mesh size and average fish length. By comparing our traps with the authorized fishing gear (hooks-and-line) we found that the size structure is larger in traps. Traps with larger mesh size were more selective. Consequently, we recommend adding traps to hooks-and-line as authorized fishing gear in the small scale fisheries of the Sonora coast, Mexico.

Products of the addition of water molecules to Al3O3- clusters: structure, bonding, and electron binding energies in Al3O4H2-, Al3O5H4-, Al3O4H2, and Al3O5H4.

Two stable products of reactions of water molecules with the Al3O3- cluster, Al3O4H2- and Al3O5H4-, are studied with electronic structure calculations. There are several minima with similar energies for both anions and the corresponding molecules. Dissociative absorption of a water molecule to produce an anionic cluster with hydroxide ions is thermodynamically favored over the formation of Al3O3-(H2O)n complexes. Vertical electron detachment energies of Al3O4H2- and Al3O5H4- calculated with ab initio electron propagator methods provide a quantitative interpretation of recent anion photoelectron spectra. Contrasts and similarities in these spectra may be explained in terms of the Dyson orbitals associated with each transition energy.

Risk factors for invasive carcinoma of the uterine cervix in Latin America

Risk factor for invasive carcinoma of the uterine cervix in Latin America

Risk factors for invasive carcinoma of the uterine cervix in Latin America

Risk factor for invasive carcinoma of the uterine cervix in Latin America

Carcinoma del endometrio: estudio de 354 casos / Endometrial carcinoma: study of 354 cases

Con objeto de conocer los factores epidemiológicos en nuestro medio y valorar la efectividad de los procedimientos terapéuticos en relación con los factores pronósticos, se analizaron retrospectivamente 354 expedientes de enfermas con carcinoma del endometrio. Su frecuencia en relación con el cáncer ginecológico fue de 5%. El promedio de edad fue 10 años menor. El 63.8% eran obesas, 40% hipertensas y 26.5% diabéticas. El adenocarcinoma fue más frecuente (77.7%), siguió el carcinoma mixto (15.6%) y el adenocantoma (6.7%). Como consecuencia del corto seguimiento no se valoró la sobrevida a 5 años; pero sí las recurrencias antes de ese límite. El tratamiento con braquiterapia intrauterina y vaginal seguido de histerectomía simple tuvo 14% de recurrencias, la misma radioterapia más histerectomía radical tuvo 12.5%. Radium vaginal más histerectomía simple 41.2% y la histerectomía simple sin radioterapia 31.4%. Estos resultados estuvieron influidos directamente por la extensión, variedad y grado histológicos del tumor. En las enfermas operadas después de radiación el 75.5% de las piezas operatorias no tenían tumor. La persistencia estuvo estrechamente relacionada con la extensión, variedad y grado histológicos del tumor, pero no con el tratamiento.