A route to high surface area, porosity and inclusion of large molecules in crystals

One of the outstanding challenges in the field of porous materials is the design and synthesis of chemical structures with exceptionally high surface areas(1). Such materials are of critical importance to many applications involving catalysis, separation and gas storage. The claim for the highest surface area of a disordered structure is for carbon, at 2,030 m(2) g(-1) (ref. 2). Until recently, the largest surface area of an ordered structure was that of zeolite Y, recorded at 904 m(2) g(-1) (ref. 3). But with the introduction of metal-organic framework materials, this has been exceeded, with values up to 3,000 m(2) g(-1) (refs 4-7). Despite this, no method of determining the upper limit in surface area for a material has yet been found. Here we present a general strategy that has allowed us to realize a structure having by far the highest surface area reported to date. We report the design, synthesis and properties of crystalline Zn4O(1,3,5-benzenetribenzoate)(2), a new metal-organic framework with a surface area estimated at 4,500 m(2) g(-1). This framework, which we name MOF-177, combines this exceptional level of surface area with an ordered structure that has extra-large pores capable of binding polycyclic organic guest molecules-attributes not previously combined in one material.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62609/1/nature02311.pd

Raman spectra of hydrogen and deuterium adsorbed on a metal-organic framework

Abstract The Raman spectra of H 2 and D 2 adsorbed on metal-organic framework-5 at various pressures (H 2 : 12.8 and 30.3 bar; D 2 : 2.2-24.5 bar) and temperatures (H 2 : 298 K; D 2 : 40-300 K) have been recorded. The shifts observed in the vibrational modes of the gases indicate that physisorption is responsible for the attractive interactions between the gas and the framework; these interactions are larger with respect to those detected for carbon materials. Ó 2005 Elsevier B.V. All rights reserved. The lack of a suitable and cost effective means of storing hydrogen Understanding the intermolecular interactions responsible for gas sorption (e.g., hydrogen) in solids (e.g., MOFs, carbon based materials, etc.) is fundamentally important to the development of new materials with improved gas sorption properties and geometries. The perturbation of the intramolecular potential resulting from intermolecular interaction with an adsorbing surface suggests that vibrational spectroscopy in general, and especially Raman spectroscopy, may turn out to be a useful technique to investigate the physical phenomena that take place because of these interactions Let us consider a pure diatomic gas: the intermolecular interactions (attractive and repulsive) with other gas molecules perturb the intramolecular potentia

Seroepidemiological Study of Viral Activity of Foot and Mouth Diseases through the Test 3ABC Elisa in Cattle from Zulia State-Venezuela

Para determinar la prevalencia de anticuerpos contra la Fiebre Aftosa (FA) mediante prueba inmunoenzimática, fueron muestreados bovinos de todos los grupos etarios de los 21 Municipios del estado Zulia. Se recolectaron mil doscientos ochenta y uno (1281) muestras de suero sanguíneo y se testearon mediante técnica de ELISA I-3ABC en el laboratorio de Diagnóstico e Investigación de Enfermedades Infecciosas de la Facultad de Ciencias Veterinarias de la Universidad del Zulia. El tamaño de la muestra se determinó mediante muestreo estratificado con fijación proporcional e intencional (nivel de confianza del 95% y error del 2,737% para población bovina y 95% de nivel de confianza con error de 4,778% para las fincas). Para el análisis estadístico de resultados los datos fueron registrados en hoja de cálculo Excel Windows y luego analizados con paquete estadístico SAS (versión 9,2). Los resultados obtenidos: prevalencia de 23,77% de fincas positivas (97/408), los Municipios con mayor porcentaje de prevalencia fueron; Machiques de Perijá, Catatumbo, Colon, y la Cañada de Urdaneta, con 57,58; 54,72; 47,62 y 31,58%, respectivamente. La seroprevalencia por estratificación de acuerdo a la cantidad de bovinos por finca (tamaño del fundo) para estratos 1; 2; 3 y 4 fue; fincas de menos de 25 animales 7,69%, entre 25 y 63 animales 8,57%, entre 64 y 119 animales 54,31% y más de 120 animales 18,75% . Los resultados por grupos etarios: grupo vacas obtuvo la mayor prevalencia con 25,18%, seguido de toros (16,67%), novillas (12,61%), novillos (10,34%), becerros (8,61%), mautas (7,85%), becerras (6,67%) y mautes (6,15%) para un total de prevalencia en todos los grupos de 13,83% de animales positivos. En conclusión, la actividad viral es alta, sobre todo en Municipios con mayor vocación pecuaria, en fincas con mayor cantidad de animales y en vacas en producción.311 - [email protected] from all age groups of 21 Municipalities of the Zulia State were sampled to determine the seroprevalence of Footand- Mouth Disease (FMD) using 3ABC ELISA. One thousand two hundred eighty one (1281) serum samples were collected and the presence of antibodies against FMD virus was assessed through 3ABC ELISA at the Infectious Diseases Diagnosis and Research laboratory of the Faculty of Veterinary Sciences, University of Zulia. Sample size was determined following a proportionally and intentionally stratified sampling technique: a confidence level of 95% and error of 2.737% at animal level; and a confidence level of 95% and error of 4.778% at herd level. Data were registered in Excel spreadsheets and then they were analyzed through SAS/STAT software (version 9.2). Results were as following: general FMD seroprevalence was 23.77% at herd level (97/408). Counties with the highest seroprevalence levels were Machiques de Perijá, Catatumbo, Colon, and la Cañada de Urdaneta (57.58, 54.72, 47.62 and 31.58%, respectively). As for herd size, observed seroprevalence was 7.69% in herds of < 25 animals, 8.57% in herds of 25-63 animals, 54.31% in herds of 64-119 animals, and 18.75% in herds of > 120 animals. As for age groups, the highest seroprevalence was observed in cows (25.18%), followed by bulls (16.67%), heifers (12.61%), steers (10.34%), male calves (8.61%), female yearlings (7.85%), female calves (6.67%), and male yearlings (6.15%) for a general FMD seroprevalence of 13.83% at animal level. In conclusion, viral circulation is high, especially in some Counties with intense livestock activities, and in farms with greater amounts of animals (especially cows)