Organic aerosols in urban and waste landfill of Algiers metropolitan area: occurrence and sources

In both downtown Algiers and the waste landfill of Oued Smar, the concentrations of particulate organic compounds comprising n-alkanes, n-alkanoic acids, n-alkan-2-ones, polycyclic aromatic hydrocarbons (PAHs), oxygenated (OPAHs), and nitrated polycyclic aromatic hydrocarbons (NPAHs) in ambient air were measured from May 1998 to February 1999. All the components except OPAHs had a tendency to strongly increase in colder weather. Motor vehicles were found to be the main source of airborne particles in downtown Algiers, while the combustion and pyrolysis processes and bacterial activity seemed to concur to the air pollution at the Oued Smar waste landfill. The biogenic emission, which was restricted to the lighter fraction of the n-alkanes and n-alkanoic acids, appeared to contribute at a lesser extent. The in-situ generation of some OPAHs and NPAHs seemed to contribute to air pollution, especially during the summertime. As expected, the ambient concentrations of NPAHs and OPAHs were lower than those of their parent PAHs. The seasonal variations in ambient NPAH and OPAH concentrations are due partly to fluctuations of precursors including NOx, 03, and OH radicals. In general, the wintertime concentrations of the organic pollutants in Algiers were similar to those measured in Europe and especially over the Mediterranean Basin. Further investigations have been planned in order to obtain a thorough knowledge of the air pollution as well as the organic content of materials burning atthe Oued Smarwaste landfill. In particular, our concern will be addressed to sources of toxic components, to formulate strategies suitable for reducing health risk for the populations living in the region of Algiers.     

Quality of milk and of Canestrato Pugliese cheese from ewes exposed to different ventilation regimens

Effects of ventilation regimen on the quality of ewes' milk and on proteolysis in Canestrato Pugliese cheese during ripening were studied. Cheeses were manufactured from the bulk milk of Comisana ewes subjected to three different ventilation regimens, which were designated low (LOV, 23 m3/h per ewe), moderate (MOV, 47 m3/h per ewe) and programmed ventilation regimen (PROV, 73 m3/h per ewe; fan set to maintain 70% relative humidity). Bulk milk was analysed for chemical and microbial composition, renneting parameters and plasmin-plasminogen activities. At 1, 15, 30 and 45 d of ripening, the cheeses were analysed for gross chemical composition, nitrogen fractions, and plasmin and plasminogen activities. The pH 4.6-insoluble nitrogen fractions were analysed by urea-PAGE. Free amino acid content was determined at the end of ripening. Lower concentrations of bulk milk somatic cell count (BMSCC) and of mesophilic bacteria were found in the MOV group than in the LOV and the PROV groups. A lower plasminogen (PG) to plasmin (PL) ratio (PG/PL) was observed in the MOV and PROV than in the LOV cheeses. Irrespective of treatment, PL activity in cheeses was higher at 15d of ripening, while a sudden decrease of PL and PG activities was observed at 30 d, which was associated with a marked increase in non-protein nitrogen. The peptide profile characterized in the urea-PAGE showed a greater intensity of alpha- and beta-CN hydrolysis in the MOV than in the PROV and LOV cheeses. The results provide evidence that a proper ventilation regimen is critical for optimizing the hygienic quality of milk and the proteolysis of Canestrato Pugliese cheese during ripening.     

Relationship of Rancimat method values at varying temperatures for virgin olive oils

Oxidative stability of VOO is widely determined by Rancimat test, an accelerated method that shortens analysis time. The most usual temperature used for Rancimat analysis is 98 °C; however several authors have reported oxidative stability values at different temperatures higher than 98 °C (110 °C, 120 °C) in order to reduce the analysis time. In this study the effect of temperature on Rancimat method for VOO analysis, measuring the method reproducibility at each temperature, has been evaluated. Method precision expressed as the relative standard deviation (RSD) was ranged from 1.14 to 5.84%, indicating that analytical method was repeatable even at 140 °C. A mathematical model is presented to transform the induction period inter-temperatures (98–140 °C). The results suggested 110 °C as the more adequate temperature since the analysis time was shortened by 63% compared to induction period obtained at 98 °C; the inter-conversion 98–110 °C presented low differences between theoretical value obtained from mathematical model and experimental value obtained by Rancimat apparatus. To shorten analysis time, 84 and 92% respectively, 120 and 130 °C can be used too; although some samples can present higher differences between theoretical and experimental induction period values because of the different oxidation mechanism at each temperature.     

Effects of somatic cell count and stage of lactation on the plasmin activity and cheese-making properties of ewe milk

The experiment was conducted from March to July 2002 using 5 intensively managed flocks of Southern Italy. In each flock, 2 groups of 50 ewes were created. The groups were designated LSCC (low somatic cell count [SCC]) when their milk SCC was lower than 500,000/mL and HSCC (high SCC) when their milk SCC was higher than 1,000,000/mL. Bulk milk and whey samples were analyzed for fat, total protein, lactose, casein, and whey protein contents. Renneting properties of milk were also determined. Moisture, NaCl, and nitrogen fractions were determined in fresh cheese curds. In addition, plasmin (PL) and plasminogen (PG) activities in milk and cheese were monitored. The proteolytic activity of plasmin by urea-polyacrylamide gel electrophoresis and the white blood cell (WBC) differentials were determined. The HSCC resulted in higher pH values in milk and in higher moisture and lower fat contents in fresh cheese curds. Moreover, a lower recovery of fat and whey proteins was obtained from the HSCC than from the LSCC raw milk. The crude protein and casein contents were higher in the HSCC than in the LSCC curds during early and midlactation; an opposite trend was observed in late lactation. Plasmin and PG activities underwent more marked fluctuations in the LSCC than in the HSCC curds through lactation. The results of this experiment demonstrate that the PL activity in ewe milk is markedly influenced by the SCC, although SCC is not the only parameter for predicting PL and PG evolution in ewe milk. The LSCC milk resulted in a higher proteolytic potential of Canestrato pugliese cheese curds.     

Characteristics of selectors of nicotine replacement therapy

Objective: To assess differences in demographic and smoking characteristics between smokers who have and have not used nicotine replacement therapy (NRT). Design: Mail survey of US smokers from a national research panel. Participants: Smokers 18 years and over who returned a survey on smoking (n = 9630). The sample was weighted to match the US smoker population on age and sex. Main outcome measures: Compared smokers who had/had not used NRT in a quit attempt (ever NRT use or over the counter (OTC) NRT use) on: demographic characteristics, nicotine dependence, history of craving and withdrawal, expected difficulty quitting, and self reported history of smoking related medical illness and psychopathology. Results: NRT users (both ever-users and OTC users) were more likely to be older, male, and better educated. They were also heavier smokers, had experienced more craving and withdrawal upon quitting, and scored higher on measures of dependence. These differences were evident among light smokers, and remained even when smoking rate and time to first cigarette were controlled. Conclusion: Smokers who elect to use NRT differ from non-NRT users in ways that predispose them to failure in cessation. Controlling for smoking rate and time to first cigarette does not eliminate these differences, even among light smokers. These differences must be considered when comparing the effectiveness of NRT among samples of smokers who self select their treatment and are likely to bias such outcome comparisons.     

Analysis of the energy efficiency of solar aided biomass gasification for pure hydrogen production

This paper presents a simulative analysis of the energy efficiency of solar aided biomass gasification for pure hydrogen production. Solar heat has been considered as available at 250 °C in three gasification processes: i) gasification reactor followed by two water gas shift reactors and a pressure swing adsorber; ii) gasification reactor followed by an integrated membrane water gas shift reactor; iii) supercritical gasification reactor followed by two flash separators and a pressure swing adsorber.     

Development of computer program for simulation of an ice bank system operation, Part I: Mathematical modelling

Since the use of standard engineering methods in the process of an ice bank performance evaluation offers neither adequate flexibility nor accuracy, the aim of this research was to provide a powerful tool for an industrial design of an ice storage system allowing to account for the various design parameters and system arrangements over a wide range of time varying operating conditions. In this paper the development of a computer application for the prediction of an ice bank system operation is presented. Static, indirect, cool thermal storage systems with external ice on coil building/melting were considered. The mathematical model was developed by means of energy and mass balance relations for each component of the system and is basically divided into two parts, the model of an ice storage system and the model of a refrigeration unit. Heat transfer processes in an ice silo were modelled by use of empirical correlations while the performance of refrigeration unit components were based on manufacturers data. Programming and application design were made in Fortran 95 language standard. Input of data is enabled through drop down menus and dialog boxes, while the results are presented via figures, diagrams and data (ASCII) files. In addition, to demonstrate the necessity for development of simulation program a case study was performed. Simulation results clearly indicate that no simple engineering methods or rule of thumb principles could be utilised in order to validate performance of an ice bank system properly.     

Peeling dynamics of fluid membranes bridged by molecular bonds: moving or breaking

Biological adhesion is a critical mechanical function of complex organisms. At the scale of cell–cell contacts, adhesion is remarkably tunable to enable both cohesion and malleability during development, homeostasis and disease. It is physically supported by transient and laterally mobile molecular bonds embedded in fluid membranes. Thus, unlike specific adhesion at solid–solid or solid–fluid interfaces, peeling at fluid–fluid interfaces can proceed by breaking bonds, by moving bonds or by a combination of both. How the additional degree of freedom provided by bond mobility changes the mechanics of peeling is not understood. To address this, we develop a theoretical model coupling diffusion, reactions and mechanics. Mobility and reaction rates determine distinct peeling regimes. In a diffusion-dominated Stefan-like regime, bond motion establishes self-stabilizing dynamics that increase the effective fracture energy. In a reaction-dominated regime, peeling proceeds by travelling fronts where marginal diffusion and unbinding control peeling speed. In a mixed reaction–diffusion regime, strengthening by bond motion competes with weakening by bond breaking in a force-dependent manner, defining the strength of the adhesion patch. In turn, patch strength depends on molecular properties such as bond stiffness, force sensitivity or crowding. We thus establish the physical rules enabling tunable cohesion in cellular tissues and in engineered biomimetic systems.     

The Columbia University sub-micron charged particle beam

A lens system consisting of two electrostatic quadrupole triplets has been designed and constructed at the Radiological Research Accelerator Facility (RARAF) of Columbia University. The lens system has been used to focus 6 MeV ⁴He ions to a beam spot in air with a diameter of 0.8 μm. The quadrupole electrodes can withstand voltages high enough to focus ⁴He ions up to 10 MeV and protons up to 5 MeV. The quadrupole triplet design is novel in that alignment is made through precise construction and the relative strengths of the quadrupoles are accomplished by the lengths of the elements, so that the magnitudes of the voltages required for focusing are nearly identical. The insulating sections between electrodes have had ion implantation to improve the voltage stability of the lens. The lens design employs Russian symmetry for the quadrupole elements.     

Retrieval of leaf area index in different vegetation types using high resolution satellite data

With the successful launch of the IKONOS satellite, very high geometric resolution imagery is within reach of civilian users. In the 1-m spatial resolution images acquired by the IKONOS satellite, details of buildings, individual trees, and vegetation structural variations are detectable. The visibility of such details opens up many new applications, which require the use of geometrical information contained in the images. This paper presents an application in which spectral and textural information is used for mapping the leaf area index (LAI) of different vegetation types. This study includes the estimation of LAI by different spectral vegetation indices (SVIs) combined with image textural information and geostatistical parameters derived from high resolution satellite data. It is shown that the relationships between spectral vegetation indices and biophysical parameters should be developed separately for each vegetation type, and that the combination of the texture indices and vegetation indices results in an improved fit of the regression equation for most vegetation types when compared with one derived from SVIs alone. High within-field spatial variability was found in LAI, suggesting that high resolution mapping of LAI may be relevant to the introduction of precision farming techniques in the agricultural management strategies of the investigated area.