Time-resolved observation of the Eigen cation in liquid water

Experimental observation and time relaxation measurement of the hydrated proton Eigen form [H(3)O(+)(H(2)O)(3)] are presented here. Vibrational time-resolved spectroscopy is used with an original method of investigating the proton excess in water. The anharmonicity of the time-resolved spectra is characteristic of the Eigen-type proton geometry. Proton relaxation occurs in less than 200 fs. A calculation of the potential energy confirms the experimental result and the Eigen cation lifetime is in good agreement with previous molecular dynamics simulations.     

Three-dimensional chemical concentration maps in a microfluidic device using two-photon absorption fluorescence imaging

Two-photon absorption fluorescence is employed within a microfluidic device to create a three-dimensional chemical concentration map for mixing uniformity characterization. This multiphoton technique images fluorescence intensity directly and provides a simple, rapid, and readily employed route to composition characterization within microfluidic systems.     

Essential oils of Retama raetam from Libya: chemical composition and antimicrobial activity

Retama raetam (Forssk) Webb & Berthel is well known in the folk medicine of North and East Mediterranean regions for the treatment of microbial infections. The powdered leaves are used to heal circumcision wounds and used as an antiseptic for wounds, skin rash and pruritus. In this study, to validate this antiseptic property, the chemical composition and antimicrobial activity of the essential oil from the flowers of R. raetam was evaluated. The oil was obtained using hydrodistillation and was analysed by gas chromatography-mass spectrometry. The antibacterial activity was achieved using disc diffusion and broth dilution assay against six bacteria species. Analysis of the essential oil revealed the presence of β-linalool (51%), 2-decen-1-ol (6.6%) and limonene (7.4%) as the major components. The results showed significant activity against microorganisms, especially Staphylococcus aureus, with inhibition zones and minimal inhibitory concentration values in the range of 5.0 mm and 3.0 mg mL?1, respectively. The results on the antibacterial activity provide scientific support for the use of these plants in traditional herbal preparations.     

Weight-based Heuristics for Constraint Satisfaction and Combinatorial Optimization Problems

In this paper, we propose mechanisms to improve instantiation heuristics by incorporating weighted factors on variables. The proposed weight-based heuristics are evaluated on several tree search methods such as chronological backtracking and discrepancy-based search for both constraint satisfaction and optimization problems. Experiments are carried out on random constraint satisfaction problems, car sequencing problems, and jobshop scheduling with time-lags, considering various parameter settings and variants of the methods.The results show that weighting mechanisms reduce the tree size and then speed up the solving time, especially for the discrepancy-based search method.     

Experimental investigation of the effect of nozzle numbers on Ranque–Hilsch vortex tube performance

The present study investigates the effects of the orifice nozzle number and the inlet pressure experimentally on the cooling performance of the counter flow-type vortex tube. The energy generation has been conducted using a stream-tek generator (model GNMD-KIT) with different numbers of nozzles (2, 3, and 6), an aspect ratio of 1:6, and an inner diameter of 7.5 mm. In the experiments, for each of the orifices, inlet pressures have been adjusted from 200–600 kPa. The energy separation investigated here focuses on the cold temperature difference and coefficient of performance for cooling. The experimental results concluded in this article prove that the greatest effect of nozzle number is for three nozzles, and hence, that nozzle number could affect the energy separation efficiently. A comparison of the present experiments with other published works has been conducted. An analytical study of the characteristics equation has been carried out to evaluate the best correlation of the ratio of cold temperature difference to the inlet temperature as a function of pressure, cold mass fraction, and nozzle number.     

Production and Characterization of a Novel Exopolysaccharide from Ramlibacter tataouinensis

The current study examines the desiccation-resistant Ramlibacter tataouinensis TTB310^T as a model organism for the production of novel exopolysaccharides and their structural features. This bacterium is able to produce dividing forms of cysts which synthesize cell-bound exopolysaccharide. Initial experiments were conducted on the enrichment of cyst biomass for exopolysaccharide production under batch-fed conditions in a pilot-scale bioreactor, with lactate as the source of carbon and energy. The optimized medium produced significant quantities of exopolysaccharide in a single growth phase, since the production of exopolysaccharide took place during the division of the cysts. The exopolysaccharide layer was extracted from the cysts using a modified trichloroacetic acid method. The biochemical characterization of purified exopolysaccharide was performed by gas chromatography, ultrahigh-resolution mass spectrometry, nuclear magnetic resonance, and Fourier-transform infrared spectrometry. The repeating unit of exopolysaccharide was a decasaccharide consisting of ribose, glucose, rhamnose, galactose, mannose, and glucuronic acid with the ratio 3:2:2:1:1:1, and additional substituents such as acetyl, succinyl, and methyl moieties were also observed as a part of the exopolysaccharide structure. This study contributes to a fundamental understanding of the novel structural features of exopolysaccharide from a dividing form of cysts, and, further, results can be used to study its rheological properties for various industrial applications.     

Stochastic multi-site supply chain planning in textile and apparel industry under demand and price uncertainties with risk aversion

A multi-product, multi-period, multi-site supply chain production and transportation planning problem, in the textile and apparel industry, under demand and price uncertainties is considered in this paper. The problem is formulated using a two-stage stochastic programming model taking into account the production amount, the inventory and backorder levels as well as the amounts of products to be transported between the different plants and customers in each period. Risk management is addressed by incorporating a risk measure into the stochastic programming model as a second objective function, which leads to a multi-objective optimization model. The objectives aim to simultaneously maximize the expected net profit and minimize the financial risk measured. Two risk measures are compared: the conditional-value-at-risk and the downside risk. As the considered objective functions conflict with each other’s, the problem solution is a front of Pareto optimal robust alternatives, which represents the trade-off among the different objective functions. A case study using real data from textile and apparel industry in Tunisia is presented to illustrate the effectiveness of the proposed model and the robustness of the obtained solutions.     

Chemical composition,phytotoxic and antifungal properties of Ruta chalepensis L. essential oils

The chemical composition, and phytotoxic and antifungal activities of the essential oils isolated by using hydrodistillation from the aerial parts of Tunisian rue were evaluated. Significant variations were observed among harvest periods. The analysis of the chemical composition by gas chromatography/mass spectrometry showed that 2-undecanone (33.4–49.8%), 2-heptanol acetate (13.5–15.4%) and α-pinene (9.8–11.9%) were the main components. The antifungal ability of rue essential oils was tested by using disc agar diffusion against ten plant pathogenic fungi. A high antifungal activity was observed for the essential oil isolated at flowering developmental phase. Furthermore, rue essential oils showed high level of herbicidal activity against several weeds.