Homogeneous Catalytic Ozonation of Lipids Involving Fe2+ and Mn2+: An Experimental and Modeling Study     

Rúbia Martins Bernardes Ramos  Ana Paula Biz  Deolinda Alvarez Tavares  Mnica Beatriz Kolicheski  Tirzh Lins Porto Dantas 《洁净——土壤、空气、水》2020,48(7-8)

Given the issue of lipids in effluent treatment systems and their negative impact on the environment, this study aimed to examine lipid degradation by homogenous catalytic ozonation with the aid of iron and manganese ions. This technology presents the possibility of completely mineralizing pollutants using hydroxyl radicals. Milk is chosen as the lipid source because of the high concentration of triglycerides in its matrix, this kind of lipid being the one found most frequently in food and, consequently, in effluent treatment systems. The milk pH value is controlled, and acidic, neutral, and basic conditions are evaluated. The rates of pseudo‐first‐order reactions and the effective value are estimated. It is shown that under acidic conditions low catalyst dosages are enough to cause the complete degradation of lipids. Under neutral conditions, a similar behavior is observed. Under basic conditions, higher catalyst dosages give higher reaction rates. The order of effectiveness of the catalysts under acidic and basic conditions is Fe²⁺ > Mn²⁺, with Mn²⁺ > Fe²⁺ under neutral conditions. Homogeneous catalytic ozonation is therefore efficient at lipid degradation. This technique is viable economically, since the lipid removal occurred at low ozone levels. In addition, the ions used as catalysts are naturally abundant.  相似文献   

The Rotation of a Non-Rigid, Non-Symmetrical Earth II: Free Nutations and Dissipative Effects     

Juan Getino  Ana B. González  Alberto Escapa 《Celestial Mechanics and Dynamical Astronomy》2000,76(1):1-21

The study of the rotation of a non-rigid, non-symmetrical Earth with a heterogeneous and stratified liquid core was recently accomplished by González and Getino (1997) through the Hamiltonian formalism. In this work that model is extended by including the effect of the dissipation arising from the mantle–core interaction due to the viscous and electromagnetic coupling. A canonical transformation to a new set of non-singular variables is performed, in order to avoid small divisors in the system of equations. Numerical estimations of the effect of the dissipation are given in form of tables and graphics, and the significance of this effect is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Behaviour of a new type of Runge–Kutta methods when integrating satellite orbits     

Ana B. González  Pablo Martín  David J. López 《Celestial Mechanics and Dynamical Astronomy》1999,75(1):29-38

Recently, González, Martín and Farto have developed new numerical methods (RKGM methods) of Runge–Kutta type and fixed step size for the numerical integration of perturbed oscillators. Moreover, it seems natural to study the behaviour of these new methods for the accurate integration of orbital problems after the application of linearizing transformation, such us KS or BF due to the fact that in these variables, the structure of the problem is of the form of perturbed oscillators, for which the methods constructed are indicated. In this paper, we check the efficiency of these new methods when integrating the satellite problem. The RKGM methods show a very good behaviour when they compete with other, classical and special, methods. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Long-term phytoplankton studies in the Bahia Blanca estuary, Argentina   总被引：3，自引：0，他引：3  

Gayoso  Ana Maria 《ICES Journal of Marine Science》1998,55(4):655-660

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Seismic hazard in regions of present day low seismic activity: uncertainties in the paleoseismic investigations along the Bree Fault Scarp (Roer Graben, Belgium)   总被引：2，自引：0，他引：2  

K. Atakan  V. Midzi  B. Moreno Toiran  K. Vanneste  T. Camelbeeck  M. Meghraoui 《Soil Dynamics and Earthquake Engineering》2000,20(5-8):415-427

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Quaternary palaeohydrological evolution of a playa lake: Salada Mediana, central Ebro Basin, Spain   总被引：3，自引：0，他引：3  

Blas L. Valero-GarcÉs  Antonio Delgado-Huertas  Ana Navas  Javier MachÍn  PenÉlope GonzÁlez-SampÉriz  & Kerry Kelts 《Sedimentology》2000,47(6):1135-1156

Sedimentary features, mineralogy, bulk geochemical composition, stable isotope analyses and pollen data from sediment cores were used to reconstruct the Late Quaternary depositional evolution of the Salada Mediana playa lake (central Ebro Basin, northeastern Spain). The 150-cm-long sediment core sequence is composed of gypsum- and dolomite-rich muds (Lower and Middle sections) and black, laminated, calcite-bearing sediments (Upper section). The Salada Mediana formed as a karstic depression in the Miocene gypsum substratum during the Late Pleistocene. The Lower section was deposited in a sulphate–carbonate saline lake that ended with a period of desiccation and basin floor deflation. Subsequent deposition (Middle section) took place in a playa-lake system. Two cycles of lower water table and expanded saline mud flats occurred. The Holocene sequence is missing, probably as a result of aeolian erosion. Sedimentation resumed only a few centuries ago, and saline pan environments dominated until modern times. The Salada Mediana facies succession was mainly governed by fluctuations in the hydrological balance, brine composition, and salinity; however, aeolian processes (detrital input and deflation) and recycling of previously precipitated salts also played a significant role.  相似文献   

Spatial and seasonal variations of the macrobenthic community and metal contamination in the Douro estuary (Portugal)   总被引：3，自引：0，他引：3  

Mucha AP  Vasconcelos MT  Bordalo AA 《Marine environmental research》2005,60(5):531-550

The macrobenthic community structure and characteristics of sediments were studied in samples collected seasonally at five stations in the lower mesotidal Douro estuary, Portugal. Sediment characterisation included grain size distribution, total-recoverable metals (Al, Fe, Mn, Zn, Cu, Cr, Pb, Ni and Cd), acid-volatile sulphides (AVS) and simultaneously extracted metals (SEM) and total organic matter contents. Spatial variation surpassed temporal variation both in terms of environmental parameters and community structure. Clear anthropogenic contamination in terms of Zn, Cr, Cu and Pb, and a positive SEM-AVS, indicating the potential bioavailability of these metals, were detected on the north bank of the estuary. Multivariate analysis revealed that in addition to natural sediment characteristics, the anthropogenic metal contamination was influencing the macrobenthic community structure. In fact, greater concentrations of Zn, Cr, Cu and Pb were associated with lower number of species and/or diversity. Finally, the dry weight-normalised metal concentrations appeared as a more useful tool than the SEM-AVS model in predicting disturbance of the macrobenthic community in the studied area.  相似文献   

On the origin of tightly wound spiral features in galactic nuclei     

P. Pismis  E. Moreno 《Astrophysics》1984,20(1):1-10

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Population biology of the portunid crab Callinectes arcuatus Ordway in the Gulf of Nicoya,Costa Rica,Central America     

Ana I. Dittel  C.E. Epifanio  Juan Bautista Chavarria 《Estuarine, Coastal and Shelf Science》1985,20(5):593-602

Tropical blue crabs Callinectes arcuatus were collected by trawling in the Gulf of Nicoya on the Pacific coast of Costa Rica, Central America. The gulf population was generally dominated by females. Adult females were common in the upper, more estuarine regions of the gulf during rainy season, but appeared to migrate to the lower gulf during dry season for spawning. Biomass varied with seasonal changes in abundance, but was generally similar to biomass of C. sapidus in Chesapeake Bay. Analysis of size frequency indicated that the population is numerically dominated by adults during January and February and that juveniles are common during the remainder of the year. Extrapolation of available data suggests that female crabs reach maturity in approximately one year after hatching.  相似文献   

Evaluation of approximations in modelling the cooling of magmatic bodies     

G. Giberti  S. Moreno  G. Sartoris 《Journal of Volcanology and Geothermal Research》1984,20(3-4)

The cooling of a magmatic intrusion is simulated by a simple model of a non-homogeneous earth, with thermal properties depending on temperature, in which heat transfer is assumed to take place by conduction only. The mathematical problem consists in solving a non-linear partial differential equation with continuity conditions on temperature and heat flux imposed at the contacts between different rocks. This has been done numerically by a finite difference method. The model is then adopted as “reality” against which a number of commonly used approximations are tested. It is found that the effect of latent heat liberation can be reasonably taken into account by attributing an effective initial temperature to the magma (errors within 20°C for t > 10⁵ years, when the temperature of the magma is still as high as 600°C); the effective specific heat approximation does not work as well. The dependence of thermal conductivity and specific heat on temperature may be eliminated by maintaining the errors within 30°C for t < 5 × 10⁵ years. The assumption that magma and country rocks have the same thermal properties allows an estimate of the temperature field in the host rocks with errors of 50°C at most. The assumption that all rocks have the same constant conductivity yields results that are far from “reality” (errors of 100–200°C even at shallow depth).  相似文献