Assessing water quality management options in the Upper Litani Basin, Lebanon, using an integrated GIS-based decision support system

The widespread and relentless discharge of untreated wastewater into the Upper Litani Basin (ULB) river system in Lebanon has reached staggering levels rendering its water unfit for most uses especially during the drier times of the year. Despite the call by governmental and non-governmental agencies to develop several wastewater treatment plants and sewage networks in an effort to control this problem, these efforts do not seem to be coordinated or based on comprehensive and integrated assessments of current and projected conditions in the basin.This paper provides an overview of the development and implementation of an integrated decision support system (DSS) designed to help policy makers and other stakeholders have a clearer understanding of the key factors and processes involved in the sewage induced degradation of surface water quality in the ULB, and formulate, assess and evaluate alternative management plans. The DSS is developed based on the WEAP model, which provides a GIS based and visual simulation environment and scenario management and analysis capabilities. The DSS was used to assess two main water quality management plans taking into consideration hydrological, spatial and seasonal variabilities. An incremental cost-effectiveness analysis was conducted to identify best buy plans. The results have confirmed the gravity of this problem and demonstrated the importance of taking immediate action on curbing this onslaught on this valuable and scarce fresh water resource.     

Control of sulfide in sewer systems by dosage of iron salts: comparison between theoretical and experimental results, and practical implications

Removal of sulfide species from municipal sewage conveyance systems by dosage of iron salts is a relatively common practice. However, the reactions that occur between dissolved iron and sulfide species in municipal sewage media have not yet been fully quantified, and practical application relies heavily on empirical experience, which is often site specific. The aim of this work was to combine theoretical considerations and empirical observations to enable a more reliable prediction of the sulfide removal efficiency for a given dosing strategy. Two main questions were addressed, regarding the dominant sulfur species that results from the oxidation of sulfide by Fe(III) and the dominant precipitation reaction between Fe(II) and sulfide species. Comparison of thermodynamic prediction obtained by an equilibrium chemistry-based computer program (MINEQL+) with experimental results obtained by dosing ferrous salts showed that the product of precipitation is FeS under all operational conditions tested. Regarding the reaction between ferric salts and sulfide species, analysis of thermodynamic data suggested that the dominant product of sulfide oxidation under typical pe/pH conditions prevailing in municipal raw wastewater is SO(4)(2-). However, comparison between sulfide removal in laboratory experiments conducted with multiple samples of raw municipal sewage with a varying composition, and the prediction of MINEQL+ showed the main sulfide oxidation product to be S(0). In order to reduce sulfide in sewage to <0.1 mgS/l a minimal molar ratio of around 1.3 Fe to 1 S should be applied when ferrous salts are used, as compared with a minimal ratio of 0.9 Fe to 1 S required when ferric salts or a mixture of ferrous and ferric salts (at a 2 Fe(III) to 1 Fe(II) ratio) are used. It appears that the high Fe to S(-II) ratios often recommended in practice can be reduced considerably by applying tight in-line control.     

La1−x Ca x NiO3 Perovskite Oxides: Characterization and Catalytic Reactivity in Dry Reforming of Methane

Perovskite-type oxides such as La_1?x Ca _x NiO₃ (x = 0.0, 0.05, 0.1, 0.3, 0.5 and 0.8) have been prepared from citrate precursors and characterized by XRD, TPR, TG-H₂ and XPS. Catalytic experiments in the reforming of CH₄ with CO₂ have been carried out in a tubular reactor at 750 °C and atmospheric pressure. After the catalytic tests the catalysts were studied by TPO and SEM. Partial substitution of La by Ca was performed to stabilize Ni particles and to prevent carbon deposition. The XRD profiles showed that the perovskite structure is the only compound identified within the 0 ≤ x ≤ 0.05 range, whereas for x ≥ 0.1 compounds such as spinel-type La₂NiO₄, NiO and CaO were observed in addition to the perovskite oxide. On the other hand, segregation of NiO, even in the unsubstituted perovskite (x = 0.0), was confirmed by TPR and XPS. The catalytic tests showed that the replacement of La by Ca, which has a lower ionic radius, favored a higher activity and stronger resistance to carbon deposition. However, this coking resistance depended on the Ca-loading and the catalysts with x = 0.05 and x = 0.8 were the most stable against deactivation.     

Electronic structure and self-assembly of cross-linked semiconductor nanocrystal arrays

We studied the electronic level structure of assemblies of InAs quantum dots and CdSe nanorods cross-linked by 1,4-phenylenediamine molecules using scanning tunneling spectroscopy. We found that the bandgap in these arrays is reduced with respect to the corresponding ligand-capped nanocrystal arrays. In addition, a pronounced sub-gap spectral structure commonly appeared which can be attributed to unpassivated nanocrystal surface states or associated with linker-molecule-related levels. The exchange of the ligands by the linker molecules also affected the structural array properties. Most significantly, clusters of close-packed standing CdSe nanorods were formed.     

Large blue shift of the biexciton state in tellurium doped CdSe colloidal quantum dots

The exciton-exciton interaction energy of tellurium doped CdSe colloidal quantum dots is experimentally investigated. The dots exhibit a strong Coulomb repulsion between the two excitons, which results in a huge measured biexciton blue shift of up to 300 meV. Such a strong Coulomb repulsion implies a very narrow hole wave function localized around the defect, which is manifested by a large Stokes shift. Moreover, we show that the biexciton blue shift increases linearly with the Stokes shift. This result is highly relevant for the use of colloidal QDs as optical gain media, where a large biexciton blue shift is required to obtain gain in the single exciton regime.     

Time efficiency and physical workload in manual picking from large containers

A common task in both trade and manufacturing, manual picking from large containers often involves considerable physical workload, as well as low efficiency and varying picking times. With quantitative evidence from an industrial setting, the paper provides detailed insights into how physical workload and picking time vary in picking from large containers. Components at a short horizontal distance from the picker and at the top instead of the bottom of the pallet are associated with shorter picking time and lower physical workload. Moreover, pallets tilted 45° towards the picker are associated with picking times that are significantly shorter on average and display smaller variations than horizontal pallets. The effects that the tilting of the pallets has on physical workload differs depending on component characteristics and from which section of the containers picking was performed. In the study, the greatest values of physical workload were observed for the tilted pallets.     

Internal stability of dynamic quantised control for stochastic linear plants

Existing analyses of ‘zooming’ quantisation schemes for bit-rate-limited control systems rely on the encoder and controller being initialised with identical internal states. Due to the quantiser discontinuity and the plant instability, it was not clear if closed-loop stability was possible if the encoder and controller commenced from different initial conditions. In this article, we consider partially observed, unstable linear time-invariant plants, with unbounded and possibly non-Gaussian noise, and propose a modified zooming-like scheme with finite-dimensional internal encoder and controller states that may not initially be identical. Using a stochastic pseudo-norm, we prove that this scheme yields mean-square stability in all closed-loop state variables, not just the plant state, under a sufficient condition involving this initial error, the plant dynamics and the channel data rate. With diminishing initial error, this condition approaches a known universal lower bound on data rates and becomes tight. Furthermore, we show that the scheme automatically corrects itself, in the sense that the errors between the internal states of the encoder and controller tend to zero stochastically with time. This suggests that the policy will maintain stability in the presence of channel errors, for sufficiently low bit error rates. We support these conclusions with simulations.     

Mucoadhesive Dosage form of Lidocaine Hydrochloride: I. Mucoadhesive and Physicochemical Characterization

The aim of this study was to characterize a buccal mucoadhesive film using lidocaine and its hydrochloride salt (LDHCL) as a model drug. Buccal films were developed using carbopol 971P as a mucoadhesive polymer, and glycerol as a plasticizer. Scanning Electron Microscope, Differential Scanning Calorimetry, X-ray powder diffraction, and Fourier Transform Infra Red techniques were used to characterize the mucoadhesive films. Bioadhesive properties were evaluated using the Universal Instron Instrument with chicken pouch as a model tissue.

LDHCL and its base were present in carbopol 971P films in a molecular dispersion state without exerting any effect on the glass transition of these films. The mucoadhesive force between the chicken pouches and the film containing glycerol did not change by time during the tested period (1–20 min), while increased with increasing the amount of glycerol (10–40% w/w of polymer content). Furthermore, a linear increase in the mucoadhesive force was accompanied by the increase in the film thickness, while a linear decrease followed by plateau was obtained when loading the patch with LDHCL at concentration above 1 mg/cm².

Loading carbopol film with lidocaine base, in a concentration up to 6 mg/cm² decreased linearly the mucoadhesive properties, which could be attributed to salt formation between the acidic carboxylic moiety of carbopol and basic lidocaine.     

Regulation of Secondary Metabolism in the Penicillium Genus

Penicillium, one of the most common fungi occurring in a diverse range of habitats, has a worldwide distribution and a large economic impact on human health. Hundreds of the species belonging to this genus cause disastrous decay in food crops and are able to produce a varied range of secondary metabolites, from which we can distinguish harmful mycotoxins. Some Penicillium species are considered to be important producers of patulin and ochratoxin A, two well-known mycotoxins. The production of these mycotoxins and other secondary metabolites is controlled and regulated by different mechanisms. The aim of this review is to highlight the different levels of regulation of secondary metabolites in the Penicillium genus.