Managing service level agreements in Premium IP networks: a business-oriented approach

This paper presents a market-enabling framework where users, content providers and network operators can interact in the seamless, transparent sale and delivery of a wide range of services. The framework allows for dynamic creation, configuration and delivery of services with quality assurance, via automated management of Service Level Agreements (SLAs). We propose an approach relying on a systemic treatment of business, service and network layer issues, which translates into a layered architecture where components belonging to different levels interact on the basis of a mediation paradigm. We use mediation as a generic term for a combination of negotiation, brokerage and state notification, jointly concurring to the realization of the entire life-cycle of a service.     

Seasonal and time variability of heavy metal content and of its chemical forms in sewage sludges from different wastewater treatment plants

Sewage sludges obtained from seven wastewater treatment plants from the province of Salamanca, Spain, were periodically sampled to determine seasonal and time variation of their elemental composition over 2000 to 2002. The aim of this paper was to provide additional insight to evaluate the potential environmental impact following soil incorporation of these materials as amendments. Aqua regia extractable metals (pseudo total content) of Cd, Cr, Cu, Ni, Pb and Zn were determined and furthermore, the main chemical forms of metals within the sludge were evaluated using a five-step fractionation procedure. All the studied sludges displayed high fertility properties due to their richness of OC, P and K. Total mean concentrations of Cd, Cr, Cu, Ni, Pb and Zn in the sludges were within the regulation of the Spanish legislation. Using an multifactor analysis of variance, significant differences between Cr, Cu, Ni, Pb and Zn pseudo total contents (p<0.01) of sludges at different sites were found while the Cd content was statistically similar. Also significant differences were found between these pseudo total contents of heavy metals in samples collected along the time after three years (0.001相似文献   

The potential of Lolium perenne for revegetation of contaminated soil from a metallurgical site

A greenhouse study was carried out to determine the possibility of using Lolium perenne for revegetation of soil from a former ferrous metallurgical plant (Naples, South Italy) contaminated by Cu, Pb and Zn at levels above current Italian regulatory limits. Surface soil samples (0-40 cm) from the facility area where raw minerals were disposed (RM1 and RM2), from a nearby unpolluted cultivated soil (C) as control and a 1:3 mixture of the control with the polluted ones (RM1+C and RM2+C) were utilized for the experiment. Revegetation trials were conducted in the greenhouse. At 90 days from seeding, shoot length, chlorophyll content, biomass yield, plant metal uptake and changes of organic carbon content and metal distribution among soil extractable phases defined by sequential extraction were determined. In the mixed substrates (RM1+C and RM2+C) concentrations of Cu, Pb and Zn were still two to three times higher than the Italian regulatory limits. Plants were healthy with 100% survival in all substrates, with no macroscopic symptoms of metal toxicity. The high pH of the soil could be one of the most important parameters responsible for the limited plant availability of the metals. On RM1, RM2 and mixed media, plants experienced retarded growth, reduced shoot length and biomass yield and higher total chlorophyll content compared to those cropped on the control soil, without any evident phytotoxic symptoms. In RM1 and RM2, the plant contents of Cu (19.3 and 12.6 mg kg(-1)), Pb (0.98 and 0.67 mg kg(-1)) and Zn (99 and 88 mg kg(-1)) were higher than that of plants grown on non-contaminated soil (Cu 10.1, Pb < 0.2, Zn 79 mg kg(-1)), but still in the range of physiologically acceptable levels. The distribution of metals in soil was slightly affected by Lolium growth with changes only regarding the organic-bound Cu and Zn pool, with reduction up to 24%. Results indicated that an acceptable healthy vegetative cover can be achieved on the contaminated soil by the proposed revegetation approach and that metals will remain stable over the study period with slight variation of the more available metal forms.     

A review of the fate of potassium in the soil-plant system after land application of wastewaters

Irrigation with wastewaters from agri-industry processes such as milk factories, piggeries, wineries and abattoirs is commonplace. These wastewaters all have high levels of potassium (K). Potassium concentration in effluents from domestic wastewater sources are relatively low, reported to vary between 10 and 30 mg L(-1). Higher levels of potassium are reported for effluents from olive oil mills, 10,000-20,000 mg KL(-1), wool scouring, 4200-13,000 mg KL(-1), cheese and lactic whey and potato processing, approximately 1800 mg KL(-1), piggery effluent, 500-1000 mg KL(-1) and winery wastewaters, up to 1000 mg KL(-1). Application of wastewaters with these high potassium levels has been found to increase the overall level of soil fertility, with the exception of alkaline effluents which can dissolve soil organic carbon. Long-term application of such wastewater may cause the build-up of soil potassium and decrease the hydraulic conductivity of the receiving soils. These potential impacts are uncertain and have been inadequately researched. Regulatory limits for potassium in drinking water have been set only by the European Union with no toxicological or physiological justification. The literature shows that grasses and legume herbages accumulate high levels of potassium, up to 5% dry weight, and some grasses, such as turfgrass are particularly tolerant to high levels of potassium, even under saline conditions. This adaptation is considered useful for increasing potassium immobilization and sustainable practices of land wastewater disposal. Potassium availability is significantly affected by the cation ratios of the wastewater, the existing soil water solution and of soil exchange sites.     

Avalanche electron injection in 4-nmSi3N4/8-nm SiO2 dielectric structure:turn-around phenomenon and Si-SiO2 interface degradation

Charge trapping and interface-state generation in very thin nitride/oxide (4-nm Si₃N₄+8-nm SiO₂) composite gate insulators are studied as a function of gate electrode work function and bottom oxide thickness. The behavior of the trapped positive charge under bias-temperature stress after avalanche electron injection (AEI) is investigated. Evidence is presented that secondary hole injection from the anode (gate/Si₃N₄ interface) and subsequent trapping near the SiO₂-Si interface result in a turnaround of the flatband voltage shift during AEI from the substrate. Just like the thermal oxides on Si, slow-state generation near the SiO₂-Si interface and boron acceptor passivation in the surface-space charge layer of the Si substrate are also observed after AEI in these nitride/oxide capacitors, and they are found to be strongly related to the secondary hole injection and trapping. Finally, interface-state generation can take place with little secondary anode hole injection and is enhanced by the occurrence of hole trapping     

Detoxification of olive mill wastewaters by zinc–aluminium layered double hydroxides

Disposal of olive mill waste waters (OMWW) represents a serious problem due to its elevated toxicity and pollution risk for environmental and aquatic bodies, which is mainly related to its polyphenol content. The use of layered double hydroxides (LDHs) or anionic clays for OMWW detoxification may represent an effective remediation process. In the current study, OMWW was treated with cold methanol to obtain a dark humic acid-like precipitate made of high molecular weight organic compounds named polymerin and a supernatant made of low molecular weight organics named OMWW-S. After precipitation with methanol, phenol content decreased from 2.14 g L^?1 to 0.80 and 1.20 g L^?1, in polymerin and OMWW-S, respectively. The chemical oxygen demand of OMWW-S decreased by about 30% with respect to raw OMWW, from 62.2 to 40.2 g L^?1. A phenolic concentrate, named OMWW-E was also obtained by ethyl acetate extraction of OMWW-S at pH 2.0. LDHs of zinc and aluminium (LDH) were obtained at room temperature and after calcination at 450 °C (LDH-450). An organo-mineral complex of LDH with polymerin (LDH-Pol) was also synthesised. Phenols from OMWW-E were sorbed preferentially on three matrices according to the following order: LDH-450 > LDH > LDH-Pol, with percent sorption of up to 73% for LDH-450. Repeated cycles of sorption of OMWW-S onto LDH-450 decreased phenol concentration by about 90%. Use of remediated water in a phytotoxicity bioassay revealed scant inhibition of germination and coleoptile elongation rate in tomato seeds and seedlings. Thus, OMWW-S after sorption onto LDH-450 could represent a low cost source of irrigation water for arid soil of the Mediterranean region.     

Microbiological safety and quality of Mozzarella cheese assessed by the microbiological survey method

Dairy products are characterized by reduced shelf life because they are an excellent growth medium for a wide range of microorganisms. For this reason, it is important to monitor the microbiological quality of dairy products and, in particular, the total viable count and concentration of Escherichia coli, as they are indicators of the hygienic state of these products. In addition, in dairy products such as Mozzarella cheese, it is important to monitor the concentration of lactic acid bacteria (LAB), as they are the major components of starter cultures used in cheese production, contributing to the taste and texture of fermented products and inhibiting food spoilage bacteria by producing growth-inhibiting substances. For these reasons, to ensure the quality and safety of their products, cheese makers should monitor frequently, during fresh cheese production, the concentration of LAB and spoilage bacteria. However, usually, small- to medium-size dairy factories do not have an internal microbiological laboratory and external laboratories of analysis are often too expensive and require several days for the results. Compared with traditional methods, the microbiological survey (MBS) method developed by Roma Tre University (Rome, Italy) allows faster and less-expensive microbiological analyses to be conducted wherever they are necessary, without the need for a microbiological laboratory or any instrumentation other than MBS vials and a thermostat. In this paper, we report the primary validation of the MBS method to monitor LAB concentration in Mozzarella cheese and the analysis, using the MBS method, of total viable count, E. coli, and LAB concentrations in the production line of Mozzarella cheese as well as during the shelf life of the product stored at 20°C. The results obtained indicate that the MBS method may be successfully used by small- to medium-size dairy factories that do not have an internal microbiological laboratory. Using the MBS method, these dairy factories can monitor autonomously the microbiological safety and quality of their products, saving both time and money.     

Remediation of metal-contaminated aqueous systems by electrochemical peroxidation: an experimental investigation

An innovative technology, electrochemical peroxidation (ECP), was investigated for remediation of mixed metal-contaminated aqueous systems by application of direct electric current to steel electrodes and of dilute H(2)O(2) solution to promote Fenton's reactions, forming sparingly soluble solid hydrous ferric oxides (HFO). Bench scale experiments evaluated the sorption and distribution of As, Be, Cd, Cr, Cs, Cu, Li, Ni, Pb, Se, V, and Zn among the soluble and solid state HFO formed as part of the ECP process. The effects of pH, hydrogen peroxide concentrations and electric current process times on the efficiency of metal removal were studied. The potential of this technology was demonstrated by effective removal at pH 3.5-4.6 and within 3 min of 0.25 A dc+100 mg H(2)O(2) l(-1), of As, Cr, Pb, Se and V with complete removal of As and Cr, >95.0%. On increasing the pH of the solution to 6.0, the retention of Be and Cu by HFO increased from 0.9-1.9% at pH 3.5 to 76.8-80.7% at pH 6.0 while concentrations of other metals, such as Pb, decreased due to precipitation of Pb hydroxy-complexes. Experiments in the absence of H(2)O(2) revealed that metals were adsorbed by HFO with the same order of affinity, As>Cr>Se>V>Be, as in the presence of H(2)O(2), but, with the exception of Cr, to a lesser extent. H(2)O(2) used in the ECP process was fundamental to increase the adsorption capacity of HFO for As, from 79.2 to 99.2%, due to the oxidation of As(III) to As(V), which has a stronger affinity for HFO. The reduced adsorption may be related to the formation of poorly ordered crystalline akaganeite, which has a lower surface area than ferrihydrite formed when H(2)O(2) was used. The optimal operating conditions were pH<6.0, an H(2)O(2) concentration of 100 mg l(-1) and a current process time not exceeding 3 min.     

Subspecies-level variation in the phytoextraction of weathered p,p'-DDE by Cucurbita pepo

Previous studies indicate that Cucurbita pepo can phytoextract highly weathered persistent organic pollutants (POPs) from soil and translocate large quantities to aerial tissues. To investigate intraspecific variability in uptake potential, a field study was conducted to quantify the phytoextraction of weathered p,p'-DDE by 21 cultivar varieties of summer squash from two distinct subspecies, C. pepo ssp texana and C. pepo ssp pepo. Significant differences exist between the two subspecies, with average root and stem to soil bioconcentration factors (BCF, dry weight ratio of contaminant concentration in the vegetation to that in the soil) of 7.22 and 5.40 for ssp pepo and of 2.37 and 0.454 for spp texana, respectively. The amounts of weathered p,p-DDE extracted from the soil by ssp pepo and ssp texana were 0.301 and 0.065%, respectively, with maximum values within each subspecies of 0.780 and 0.182%, respectively. The quantities of 14 inorganic elements were determined in both the soil and tissues (roots, stems, leaves, and fruit) of all 21 cultivar varieties. Phosphorus concentrations in the tissues of ssp pepo were 14 (fruit)-73% (stems) greater than those of ssp texana. These data support our hypothesis that the unique ability of certain cultivars of C. pepo to phytoextract highly weathered POPs from soil is the result of low molecular weight organic acid exudation as a unique phosphorus acquisition mechanism.     

Heavy metal contamination of the soils used for stocking raw materials in the former ILVA iron-steel industrial plant of Bagnoli (southern Italy)

The total contents and the chemical and mineralogical forms of the metals Fe, Al, Cu, Co, Cr, Pb, Zn, Ni and Mn in the horizons of a soil profile, representative of an area devoted to stocking raw materials in the dismantled iron-steel industrial plant of ILVA of Bagnoli (Naples), were studied by physical and chemical methods. The geological setting of the study area is the result of volcanic activity in the Phlegrean Fields, a group of polygenic volcanoes to the west of Naples, which give rise to the parent soil material. Soil morphology appeared to be strongly disturbed by the occurrence and stratification of materials used in the industrial process. Fine sediments illuviation down the profile resulted in the occurrence of silt and clay coatings. The total contents of Cu, Co, Cr, Pb, Zn and Ni, in the whole soil samples, especially in the surface layers, were above the regulatory levels (Cu 120, Co 20, Cr 150, Pb 100, Zn 150, Ni 120 mg kg(-1)) stated by the Italian Ministry of Environment for soils in public, private and residential areas, and below the levels (Cu 600, Co 250, Cr 800, Pb 1000, Zn 1500, Ni 500 mg kg(-1)) outlined for soils and subsoils of industrial and commercial areas (Gazzetta Ufficiale della Repubblica Italiana, 1999). Speciation of heavy metals and the determination of the different chemical pools in the fraction < 2 mm identified the large presence of elements trapped in the mineralogical structure of oxides and silicates and occluded in easily reducible manganese or iron oxides. A constant amount of Cu was associated with organic compounds. A significant amount of Zn (> 20%) was extracted in diluted acetic acid solution, indicating that the element was present in a more readily and potentially available form. In the clay fraction (< 2 microm) heavy metals were associated with both amorphous and crystalline iron forms. The presence of iron-rich clay coatings was evident in the illuvial pores of deeper horizons. Enrichment in Cu, Co, Cr and Zn of the coatings was observed. Possible translocation of metals down through the soil profile mainly bound to fine particles of relatively inert forms of iron is hypothesised. The dispersion in water of the clay fraction resulted in an average percentage dispersion of approximately 20% with a peak of 41.7% at 68-72 cm depth. Magnetite, goethite, hematite, calcite and quartz mixed with K-feldspars, clynopyroxenes and mica occurred in the coarse sand fractions (2-0.2 mm) of the soil samples from all the surface horizons. Talcum and goethite together with clay minerals at 1.4 nm, kaolinite and illite were found in the clays (< 2 microm).