Hydrocracking of long paraffins over Pt-Pd/WO3-ZrO2 in the presence of sulfur and aromatic impurities

The hydrocracking of long paraffins in the presence of sulfur and aromatic impurities using Pt–Pd/WO3–ZrO2 was assessed. The catalysts were tested for n-hexadecane hydrocraking in the presence and absence of several poisons, benzothiophene, quinolein, carbon disulfide, benzene, and naphthalene. At small impurity levels, aromatics are beneficial for the hydrocracking of long paraffins because they increase the liquid yield and reduce the cracking to light gases. Sulfur compounds were strong poisons of the activity. Benzothiophene was the strongest, producing the highest decline in activity and being more strongly chemisorbed than basic quinolein. Sulfur poisoning drastically affected the hydrocracking activity, indicating that acid isomerization cracking on WO3–ZrO2 follows a bifunctional mechanism with a big influence of the metal function. Incorporation of Pd to Pt/WO3–ZrO2 reduced the sulfur poisoning, with Pt–Pd (3:1)/WO3–ZrO2 being the best catalyst for stable hydrocracking of long paraffins in the presence of sulfur. This catalyst retained most of the activity of the Pt/WO3–ZrO2 parent material while being less affected by sulfur.Fil: Busto, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Grau, Javier Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Sepulveda, Jorge H.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Tsendra, Oksana. National Academy of Sciences. Chuiko Institute of Surface Chemistry; UcraniaFil: Vera, Carlos Roman. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentin

Preferencias hacia carne de cordero en supermercados de Temuco, región de la Araucanía, Chile

Lobos, G (Lobos, German). Univ Talca, Escuela Ingn Comercial, Talca, ChileThe low levels of consumption of lamb meat in Chile suggest the need for studies on consumer preferences in order to orient production. A study with this object was carried out to evaluate preferences for various cuts, breeds, state (fresh or frozen) and price of lamb's meat among supermarket buyers in Temuco, Chile, and the existence of different market segments, through a survey of 400 persons. Using a fractional factorial design for conjoint analysis, it was determined that the state of the meat was more important than the cut, the price and the breed, with a preference for meat in half carcasses and quarters, Araucano lamb, fresh, at a medium price level. Four consumer segments were distinguished by analysis of hierarchic conglomerates. The majority group (47.7%) was sensitive to the state and the cut, with preference for meat in quarters, fresh, Texel breed. The second group (25.3%) was sensitive to the breed, presenting the strongest preferences for meat in whole carcass, fresh, Araucano lamb. The third group (14.3%) was sensitive to the price, preferred meat in quarters, fresh, Araucano lamb. The minority group (12.7%) was sensitive to the state and price, preferring meat in quarters, Texel breed, and was the only group which preferred frozen meat and would pay a higher price. The segments were distinguished by age, ethnic origin and satisfaction with food-related life. Thus the commercialisation strategy for lamb in supermarkets in Temuco should concentrate principally on the sale of fresh meat cut in quarter

Taxonomic and biological notes on Andinopanurgus (Hymenoptera: Andrenidae)

This is the publisher's version, also available electronically from https://journals.ku.edu/index.php/melittology/indexAdditional taxonomical and biological information on Andinopanurgus Gonzalez & Engel, a recently described subgenus of Protandrena Cockerell occurring at mid- and high elevations (1100–3400 m) in the Andes from Venezuela to Peru, is provided. The male of Protandrena maximina Gonzalez & Ruz is described and figured for the first time. New geographical records, an updated key to species, and observations on the foraging behavior of P. guarnensis Gonzalez & Ruz on flowers of cultivated potatoes (Solanum tuberosum L. [Solanaceae]) in central Colombia are also provided

Estilos de vida en relación a la alimentación y hábitos alimentarios dentro y

Lobos, G (Lobos, German). Univ Talca, Fac Ciencias Empresariales, Escuela Ingn Comercial, Talca, ChileResumen Objetivo: Distinguir tipologías de consumidores en base a su estilo de vida en relación a la alimentación en las principales comunas de la Región Metropolitana de Santiago, Chile, y caracterizarlas según sus hábitos de consumo de alimentos dentro y fuera del hogar, características sociodemográficas y su nivel de satisfacción con su alimentación. Material y método: Se aplicó un cuestionario estructurado a una muestra de 951 personas en las principales comunas de la Región Metropolitana de Santiago (más de 100.000 habitantes). El instrumento de recogida de información incluyó una adaptación del cuestionario de estilos de vida en relación a la alimentación (FRL) y la escala SWFL (Satisfaction with Food-related Life). Se consultaron los hábitos de consumo de alimentos dentro y fuera del hogar y variables de clasificación sociodemográfica de los encuestados. Resultados: Mediante análisis cluster se distinguieron cinco tipologías con diferencias significativas en los cinco componentes obtenidos del FRL, con análisis factorial de componentes principales. Las tipologías presentaron distinto perfil de género, edad y nivel socioeconómico y difirieron en los puntajes obtenidos en la SWFL. Se diferenciaron en la frecuencia en que la persona almuerza, toma once y cena en su hogar. Respecto a las comidas fuera del hogar, las tipologías se distinguieron según la frecuencia de comidas en restaurantes, locales de comida rápida y en la compra de comida preparada. Conclusiones: Un estilo de vida en relación a la alimentación con baja implicación y disfrute de los alimentos se asocia con un mayor nivel socioeconómico y menor edad de las personas. Adicionalmente, se asocia con comportamientos alimentarios poco saludables y no beneficiosos para las personas, como una mayor frecuencia de comidas en restaurantes y de compra de comida preparada, junto a una menor frecuencia de comidas en el hogar, lo que estaría influyendo en un nivel inferior de satisfacción con la alimentación

COMMUNITY ECOLOGY -ORIGINAL PAPER Coexistence in streams: do source-sink dynamics allow salamanders to persist with fish predators?

Abstract Theory suggests that source-sink dynamics can allow coexistence of intraguild predators and prey, but empirical evidence for this coexistence mechanism is limited. We used capture-mark-recapture, genetic methods, and stable isotopes to test whether source-sink dynamics promote coexistence between stream fishes, the intraguild predator, and stream salamanders (Dicamptodon aterrimus), the intraguild prey. Salamander populations from upstream reaches without fish were predicted to maintain or supplement sink populations in downstream reaches with fish. We found instead that downstream reaches with fish were not sinks even though fish consumed salamander larvae-apparent survival, recruitment, and population growth rate did not differ between upstream and downstream reaches. There was also no difference between upstream and downstream reaches in net emigration. We did find that D. aterrimus moved frequently along streams, but believe that this is a response to seasonal habitat changes rather than intraguild predation. Our study provides empirical evidence that local-scale mechanisms are more important than dispersal dynamics to coexistence of streams salamanders and fish. More broadly, it shows the value of empirical data on dispersal and gene flow for distinguishing between local and spatial mechanisms of coexistence

Heterogeneous malaria transmission in long-term Afghan refugee populations: a cross-sectional study in five refugee camps in northern Pakistan.

BACKGROUND: Afghan refugees in northern Pakistan have been resident for over 30 years and current information on malaria in this population is sparse. Understanding malaria risk and distribution in refugee camps is important for effective management both in camps and on return to Afghanistan. METHODS: Cross-sectional malariometric surveys were conducted in five Afghan refugee camps to determine infection and exposure to both Plasmodium falciparum and Plasmodium vivax. Factors associated with malaria infection and exposure were analysed using logistic regression, and spatial heterogeneity within camps was investigated with SatScan. RESULTS: In this low-transmission setting, prevalence of infection in the five camps ranged from 0-0.2 to 0.4-9 % by rapid diagnostic test and 0-1.39 and 5-15 % by polymerase chain reaction for P. falciparum and P. vivax, respectively. Prevalence of anti-malarial antibodies to P. falciparum antigens was 3-11 and 17-45 % for P. vivax antigens. Significant foci of P. vivax infection and exposure were detected in three of the five camps. Hotspots of P. falciparum were also detected in three camps, only one of which also showed evidence of P. vivax hotspots. CONCLUSIONS: There is low and spatially heterogeneous malaria transmission in the refugee camps in northern Pakistan. Understanding malaria risk in refugee camps is important so the malaria risk faced by these populations in the camps and upon their return to Afghanistan can be effectively managed

Scars of Invariant Manifolds in Interacting Chaotic Few-Body Systems

We present a novel extension of the concept of scars for the wave functions of classically chaotic few-body systems of identical particles with rotation and permutation symmetry. Generically there exist manifolds in classical phase space which are invariant under the action of a common subgroup of these two symmetries. Such manifolds are associated with highly symmetric configurations. If sufficiently stable, the quantum motion on such manifolds displays a notable enhancement of the revival in the autocorrelation function which is not directly associated with individual periodic orbits. Rather, it indicates some degree of localization around an invariant manifold which has collective characteristics that should be experimentally observable.Comment: 4 pages, RevTeX, 4 PS/EPS-figures, uses psfig.sty, quantum computation changed, to be published in Physical Review Letter

Episodic photic zone euxinia in the northeastern Panthalassic Ocean during the end-Triassic extinction

Severe changes in ocean redox, nutrient cycling, and marine productivity accompanied most Phanerozoic mass extinctions. However, evidence for marine photic zone euxinia (PZE) as a globally important extinction mechanism for the end-Triassic extinction (ETE) is currently lacking. Fossil molecular (biomarker) and nitrogen isotopic records from a sedimentary sequence in western Canada provide the first conclusive evidence of PZE and disrupted biogeochemistry in neritic waters of the Panthalassic Ocean during the end Triassic. Increasing water-column stratification and deoxygenation across the ETE led to PZE in the Early Jurassic, paralleled by a perturbed nitrogen cycle and ecological turnovers among noncalcifying groups, including eukaryotic algae and prokaryotic plankton. If such conditions developed widely in the Panthalassic Ocean, PZE might have been a potent mechanism for the ETE.National Science Foundation (U.S.) (Grant EAR-1147402)Exobiology Program (U.S.) (Grants NNX09AM88G and NNA08CN84A)American Association of Petroleum Geologists (Grant-In-Aid)Mary-Hill and Bevan M. French Fund for Impact Geolog

Quantum dissipation due to the interaction with chaotic degrees-of-freedom and the correspondence principle

Both in atomic physics and in mesoscopic physics it is sometimes interesting to consider the energy time-dependence of a parametrically-driven chaotic system. We assume an Hamiltonian ${\cal H}(Q,P;x(t))$ where $x(t)=Vt$. The velocity $V$ is slow in the classical sense but not necessarily in the quantum-mechanical sense. The crossover (in time) from ballistic to diffusive energy-spreading is studied. The associated irreversible growth of the average energy has the meaning of dissipation. It is found that a dimensionless velocity $v_{PR}$ determines the nature of the dynamics, and controls the route towards quantal-classical correspondence (QCC). A perturbative regime and a non-perturbative semiclassical regime are distinguished.Comment: 4 pages, clear presentation of the main poin

Evaluation of vegetation communities, water table, and peat composition as drivers of greenhouse gas emissions in lowland tropical peatlands

© 2019 Elsevier B.V. Tropical peatlands are globally important source of greenhouse gases to the atmosphere, but data on carbon fluxes from these ecosystems is limited due to the logistical challenges of measuring gas fluxes in these ecosystems. Proposals to overcome the difficulties of measuring gas carbon fluxes in the tropics include remote sensing (top-down) approaches. However, these require information on the effect of vegetation communities on carbon dioxide (CO2) and methane (CH4) fluxes from the peat surface (bottom-up). Such information will help reducing the uncertainty in current carbon budgets and resolve inconsistencies between the top-down and bottom-up estimates of gas fluxes from tropical peatlands. We investigated temporal and spatial variability of CO2 and CH4 fluxes from tropical peatlands inhabited by two contrasting vegetation communities (i.e., mixed forest and palm swamp) in Panama. In addition, we explored the influence of peat chemistry and nutrient status (i.e., factorial nitrogen (N) and phosphorus (P) addition) on greenhouse gas fluxes from the peat surface. We found that: i) CO2 and CH4 fluxes were not significantly different between the two vegetation communities, but did vary temporally across an annual cycle; ii) precipitation rates and peat temperature were poor predictors of CO2 and CH4 fluxes; iii) nitrogen addition increased CH4 fluxes at the mixed forests when the water table was above the peat surface, but neither nitrogen nor phosphorus affected gas fluxes elsewhere; iv) gas fluxes varied significantly with the water table level, with CO2 flux being 80% greater at low water table, and CH4 fluxes being 81% higher with the water table above the surface. Taken together, our data suggested that water table is the most important control of greenhouse gas emissions from the peat surface in forested lowland tropical peatlands, and that neither the presence of distinct vegetation communities nor the addition of nutrients outweigh such control