Incidence de la minéralisation des eaux algériennes sur la réactivité de composés organiques vis-à-vis du chlore

Cette étude présente les principaux résultats se rapportant d'une part à l'évolution des consommations en chlore par des composés organiques en solutions synthétiques de minéralisation variable. D'autre part, quelques essais sont consacrés aux possibilités de formation de sous- produits de la chloration tels les trihalométhanes.Les différences de réactivité entre les composés simples (phénol, résorcinol, aniline) et les substances humiques, déjà observées en eau distillée, ont pu également être mises en évidence lors de leur dilution dans des milieux minéralisés (eaux de sources ou de forages). L'influence de la minéralisation, appréhendée par le paramètre "conductivité" ou par des teneurs variables en éléments minéraux spécifiques, s'est concrétisée par des écarts souvent considérables entre les potentiels de consommation en chlore en eau distillée et ceux en eaux minéralisées.La présence d'ions bromures dans les eaux les plus minéralisées induit en particulier une formation plus importante des THM bromés. L'intervention d'ions chlorures et sulfates, en provoquant une diminution des potentiels de consommation en chlore, peut rendre plus complexe le schéma réactionnel du chlore avec les différentes entités réactives présentes dans une eau naturelle.L'application du procédé de chloration à des eaux de surface algériennes a permis de distinguer entre les eaux très minéralisées du sud algérien et celles moins minéralisées du nord du pays.Leur réactivité vis-à-vis du chlore s'est trouvée directement liée à leurs caractéristiques physico-chimiques.Les différences de réactivité relevées peuvent être attribuées d'une part à la variabilité de la proportion en matériel humique et d'autre part aux teneurs relatives en éléments minéraux promoteurs ou inhibiteurs de la réaction de chloration.The organic compounds studied during this work are simple aromatic structures (phenol, resorcinol, aniline), as well as macromolecular structures (humic substances). These compounds are representative of natural organic matter in surface waters. Various studies (De Laat et al., 1982; Norwood and Christman, 1987; Legube et al., 1990) showed that chlorination of these organic substances led to a strong chlorine consumption and the formation of volatile and non-volatile organohalogenated compounds. However, the majority of these experiments were conducted in aqueous media at very low ionic strength or in distilled water. The aim of the present study was to observe the reactivity of organic compounds in mineralised media. Indeed, Algerian waters are often very mineralised, excessively hard with high amounts of chloride and sulphate (Achour, 2001). In addition, humic substances can account for 60 to 90% of the total organic carbon (TOC) in most surface waters used to produce drinking water (Achour and Moussaoui, 1993).The first part of this study involved the investigation of the impact of the overall parameter "total mineralisation", which can be directly related to conductivity measurements in the dilution waters. In addition to distilled water, dilution media for the organic compounds included four ground waters initially free of organic matter and residual chlorine. Figure 1 shows the geographic location of sampling sites for the waters of Drauh and Oued Biskra (Biskra) as well as those of waters of Ifri (Bedjaïa) and Youkous (Tebessa). Their main physico-chemical characteristics are presented in Table 1. The influence of certain specific inorganic constituents such as ammonia, bromide, chloride and sulphate is also observed on the chlorination of the organic compounds tested. The objective was to determine and to compare chlorine consumption potentials respectively for the simple organic compounds (D) and the humic substances (PCCl2) in media with differing degrees of mineralisation and under controlled conditions (pH, contact time and chlorine dose applied). Chlorination ratio is expressed for the simple organic compounds by r=moles of introduced chlorine/moles of organic compound and for the humic substances by m=mg of introduced chlorine/mg of humic substances.Tests were performed to evaluate the formation of trihalomethanes (chloroform and brominated trihalomethanes). Analysis was done by gas chromatography using a head space method. The main experimental chlorination conditions for the synthetic solutions of organic compounds are summarised in Table 2. The results obtained (Table 3) show that the organic compounds tested remain very reactive towards chlorine, whatever the mineralisation of the dilution media. Potentials of chlorine consumption in distilled water and in mineralised waters are different (E), showing the obvious effect of the degree of mineralisation (Table 4). The reactivity of humic substances seems intermediary between the structures of resorcinol and phenol or aniline. The highest variations (E) between distilled water and the natural mineralised waters were observed in the case of the most highly mineralised water (water of Oued Biskra); generally the gaps decreased in the order E (Oued Biskra) > E (Ifri) > E (Youkous) > E (Drauh). In studies at different pH values, the oxidation capacity of chlorine was exerted more vigorously at circumneutral pH values (Table 5). For phenol and humic substances, gaps are more meaningful within five minutes of contact time, during the first step of the chlorination reaction (Table 6).Total mineralisation does not seem to be the only parameter able to affect the reactivity of organic matter. The composition of the inorganic matrix must be considered too. Thus, according to the relative proportions of ammonia and bromides, competitive reactions (chlorine/organic matter and chlorine/inorganics) will condition chlorine consumption and the formation of trihalomethanes (THMs). For waters with a low ammonia/bromide ratio, an increase of the bromide concentration can induce a significant degradation of the chlorine consumption potentials, even for resorcinol, which is habitually more reactive with chlorine than with bromide (Figure 2). In waters with high levels of bromides (waters of Drauh and Oued Biskra), bromoform may be formed (Table 7). The presence of high concentrations of chloride and sulphate in aqueous solutions with humic substances seems to induce a reduction of chlorine consumption potentials (Figures 3 and 4). Several hypotheses can be advanced to explain this phenomenon, especially the decrease of activity of the chlorinating element by the increase of the ionic strength of the aqueous media. At the same time, it can be assumed that chlorinated entities may be formed with less reactivity than hypochlorous acid. The reduction of chlorine consumption is less significant in the presence of sulphates than chlorides. Moreover, the cation associated with sulphate seems to have an effect on the reactivity of the humic substances towards to chlorine.In the second part of the work, chlorination was applied to four surface water samples. The sampling sites (Figure 1) relate to reservoir waters of Souk El Djemâa (Tizi-Ouzou), Aïn Zada (Sétif), Foum El Gherza (Biskra) and Fontaine des gazelles (Biskra). Amounts of humic material are relatively important and constitute about 60% of the TOC found in the raw waters. The mineralisation in these waters is considerable, particularly for waters in the southern part of the country (Table 8). Chlorine consumption and THMs formed seem to be correlated with the nature and concentration of organic matter, as well as with the inorganic component of these waters (Table 9). Chlorination of water samples taken from the north of Algeria (Aïn Zada and Souk El Djemâa) leads to higher values of chlorine consumption potentials than for water samples taken from the south of the country. Taking into account the results obtained on synthetic solutions, this trend can be explained by the appreciable contents of humic substances as well as by a lower degree of mineralisation of waters in the north. It also interesting to note that proportion of brominated trihalomethanes compared to the total trihalomethanes increases not only with the initial concentration of bromides but also with increasing levels of chlorides and sulphates. Highly mineralised waters, containing humic material, seem therefore to favour numerous competitive reactions during chlorination

Menopause and metabolic syndrome in Tunisian women

Objectives. This study aimed to evaluate the effect of menopausal status on the risk of metabolic syndrome (MetS) in Tunisian women. Methods. We analyzed a total of 2680 women aged between 35 and 70 years. Blood pressure, anthropometric indices, fasting glucose, and lipid profile were measured. The MetS was assessed by the modified NCEP-ATPIII definition. Results. The mean values of waist circumference, blood pressure, plasma lipids, and fasting glucose were significantly higher in postmenopausal than in premenopausal women, a difference that was no longer present when adjusting for age. Except for hypertriglyceridaemia, the frequency of central obesity, hyperglycemia, high blood pressure, and high total cholesterol was significantly higher in postmenopausal than in premenopausal women. After adjusting for age, the significance persisted only for hyperglycemia. The overall prevalence of MetS was 35.9%, higher in postmenopausal (45.7% versus 25.6%) than in premenopausal women. A binary logistic regression analysis showed that menopause was independently associated with MetS (OR = 1.41, 95% CI 1.10-1.82) after adjusting for age, residence area, marital status, family history of cardiovascular disease, education level, and occupation. Conclusions. The present study provides evidence that the MetS is highly prevalent in this group of women. Menopause can be a predictor of MetS independent of age in Tunisian women

The quiet Sun average Doppler shift of coronal lines up to 2 MK

The average Doppler shift shown by spectral lines formed from the chromosphere to the corona reveals important information on the mass and energy balance of the solar atmosphere, providing an important observational constraint to any models of the solar corona. Previous spectroscopic observations of vacuum ultra-violet (VUV) lines have revealed a persistent average wavelength shift of lines formed at temperatures up to 1 MK. At higher temperatures, the behaviour is still essentially unknown. Here we analyse combined SUMER/SoHO and EIS/Hinode observations of the quiet Sun around disk centre to determine, for the first time, the average Doppler shift of several spectral lines formed between 1 and 2 MK, where the largest part of the quiet coronal emission is formed. The measurements are based on a novel technique applied to EIS spectra to measure the difference in Doppler shift between lines formed at different temperatures. Simultaneous wavelength-calibrated SUMER spectra allow establishing the absolute value at the reference temperature of 1 MK. The average line shifts at 1 MK < T < 1.8 MK are modestly, but clearly bluer than those observed at 1 MK. By accepting an average blue shift of about (-1.8+/-0.6) km/s at 1 MK (as provided by SUMER measurements), this translates into a maximum Doppler shift of (-4.4+/-2.2) km/s around 1.8 MK. The measured value appears to decrease to about (-1.3+/-2.6) km/s at the Fe XV formation temperature of 2.1 MK. The measured average Doppler shift between 0.01 and 2.1 MK, for which we provide a parametrisation, appears to be qualitatively and roughly quantitatively consistent with what foreseen by 3-D coronal models where heating is produced by dissipation of currents induced by photospheric motions and by reconnection with emerging magnetic flux.Comment: 9 pages, 10 figures. Astronomy and Astrophysics (in press

Influence of Gravity on noncommutative Dirac equation

In this paper, we investigate the influence of gravity and noncommutativity on Dirac equation. By adopting the tetrad formalism, we show that the modified Dirac equation keeps the same form. The only modification is in the expression of the covariant derivative. The new form of this derivative is the product of its counterpart given in curved space-time with an operator which depends on the noncommutative $\theta$-parameter. As an application, we have computed the density number of the created particles in presence of constant strong electric field in an anisotropic Bianchi universe.Comment: 9 pages, correct some miprints, Accepted for publication in journal of Mod. Phys. Letters

A cost effectiveness analysis of salt reduction policies to reduce coronary heart disease in four Eastern Mediterranean countries.

BACKGROUND: Coronary Heart Disease (CHD) is rising in middle income countries. Population based strategies to reduce specific CHD risk factors have an important role to play in reducing overall CHD mortality. Reducing dietary salt consumption is a potentially cost-effective way to reduce CHD events. This paper presents an economic evaluation of population based salt reduction policies in Tunisia, Syria, Palestine and Turkey. METHODS AND FINDINGS: Three policies to reduce dietary salt intake were evaluated: a health promotion campaign, labelling of food packaging and mandatory reformulation of salt content in processed food. These were evaluated separately and in combination. Estimates of the effectiveness of salt reduction on blood pressure were based on a literature review. The reduction in mortality was estimated using the IMPACT CHD model specific to that country. Cumulative population health effects were quantified as life years gained (LYG) over a 10 year time frame. The costs of each policy were estimated using evidence from comparable policies and expert opinion including public sector costs and costs to the food industry. Health care costs associated with CHDs were estimated using standardized unit costs. The total cost of implementing each policy was compared against the current baseline (no policy). All costs were calculated using 2010 PPP exchange rates. In all four countries most policies were cost saving compared with the baseline. The combination of all three policies (reducing salt consumption by 30%) resulted in estimated cost savings of $235,000,000 and 6455 LYG in Tunisia;$39,000,000 and 31674 LYG in Syria; $6,000,000 and 2682 LYG in Palestine and$1,3000,000,000 and 378439 LYG in Turkey. CONCLUSION: Decreasing dietary salt intake will reduce coronary heart disease deaths in the four countries. A comprehensive strategy of health education and food industry actions to label and reduce salt content would save both money and lives

Learning lessons from the 2011 Van Earthquake to enhance healthcare surge capacity in Turkey

Historically, Turkey has adopted a reactive approach to natural hazards which resulted in significant losses. However, following the 1999 Kocaeli Earthquake, a more proactive approach has been adopted. This study aims to explore the way this new approach operates on the ground. A multi-national and multi-disciplinary team conducted a field investigation following the 2011 Van Earthquake to identify lessons to inform healthcare emergency planning in Turkey and elsewhere. The team interviewed selected stakeholders including, healthcare emergency responders, search and rescue services, ambulance services, and health authority representatives, in addition to conducting a focus group. Data were analysed according to an open coding process and SWOT analysis. The findings suggest that the approach succeeded in developing a single vision by consolidating official efforts in a more structured way, mobilising many governmental and non-governmental organisations, securing significant amounts of resources including physical and human, and increasing the resilience and flexibility of infrastructure to expand its capacity. However, more attention is required to the development of stronger management procedures and acquisition of further resources

Canine respiratory coronavirus employs caveolin-1-mediated pathway for internalization to HRT-18G cells

Canine respiratory coronavirus (CRCoV), identified in 2003, is a member of the Coronaviridae family. The virus is a betacoronavirus and a close relative of human coronavirus OC43 and bovine coronavirus. Here, we examined entry of CRCoV into human rectal tumor cells (HRT-18G cell line) by analyzing co-localization of single virus particles with cellular markers in the presence or absence of chemical inhibitors of pathways potentially involved in virus entry. We also targeted these pathways using siRNA. The results show that the virus hijacks caveolin-dependent endocytosis to enter cells via endocytic internalization

Application of the mixture design to decolourise effluent textile wastewater using continuous stirred bed reactor

Important pollutants in textile effluents are mainly recalcitrant organics, colours, toxicants and inhibitory compounds, surfactants, chlorinated compounds (AOX), pH and salts. An aerobic system using a continuous stirred bed reactor (SBR) was continuously operated at constant temperature and fed with textile wastewater (pH 7 and total chemical oxygen demand (COD) 1 700 mg/ℓ).This report is focused on the decolourisation treatment of effluent by a bacterial consortium (Sphingomonas paucimobilis, Bacillus sp. and filamentous bacteria). The influence of the different mixtures of 3 strains on the decolourisation of effluent (cell density fixed at OD600 = 1) was studied using an equilateral triangle diagram and mixture experimental design to assess colour and COD removal during species evolution. With the aid of analysis software (Minitab 14.0), the formulation of pure culture was optimised for several responses and the best formulation obtained. The results suggested that the highest predictable specific decolourisation rate and chemical oxygen demand (COD) were 86.72% and 75.06%, respectively. Regression coefficients between the variables and the responses of decolourisation and COD removal were, respectively, R2 = 72.48% and 54.28%, which indicated excellent evaluation of experimental data by the polynomial regression model. UV-visible analysis confirmed biodegradation of effluent.Keywords: textile wastewater, bacterial decolourisation, response surface, mixture design, SB

Degenerate higher order scalar-tensor theories beyond Horndeski up to cubic order

We present all scalar-tensor Lagrangians that are cubic in second derivatives of a scalar field, and that are degenerate, hence avoiding Ostrogradsky instabilities. Thanks to the existence of constraints, they propagate no more than three degrees of freedom, despite having higher order equations of motion. We also determine the viable combinations of previously identified quadratic degenerate Lagrangians and the newly established cubic ones. Finally, we study whether the new theories are connected to known scalar-tensor theories such as Horndeski and beyond Horndeski, through conformal or disformal transformations

A Mathematical model for Astrocytes mediated LTP at Single Hippocampal Synapses

Many contemporary studies have shown that astrocytes play a significant role in modulating both short and long form of synaptic plasticity. There are very few experimental models which elucidate the role of astrocyte over Long-term Potentiation (LTP). Recently, Perea & Araque (2007) demonstrated a role of astrocytes in induction of LTP at single hippocampal synapses. They suggested a purely pre-synaptic basis for induction of this N-methyl-D- Aspartate (NMDA) Receptor-independent LTP. Also, the mechanisms underlying this pre-synaptic induction were not investigated. Here, in this article, we propose a mathematical model for astrocyte modulated LTP which successfully emulates the experimental findings of Perea & Araque (2007). Our study suggests the role of retrograde messengers, possibly Nitric Oxide (NO), for this pre-synaptically modulated LTP.Comment: 51 pages, 15 figures, Journal of Computational Neuroscience (to appear