Glasses formation,characterization, and crystal-structure determination in the Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>–Sb<Subscript>2</Subscript>O<Subscript>3</Subscript>–TeO<Subscript>2</Subscript> system prepared in an air

A glass-forming domain is found and studied within Bi₂O₃–Sb₂O₃–TeO₂ system. The glasses composition were obtained in pseudo-binary xSbO_1.5, (1−x)TeO₂ for 0.05 ≤ x ≤ 0.20. The constitution of glasses in the system Sb₂O₃–TeO₂ was investigated by DSC, Raman, and Infrared spectroscopy. The influence of a gradual addition of the modifier oxides on the coordination geometry of tellurium atoms has been elucidated based Infrared and Raman studies and showed the transition of TeO₄, TeO₃₊₁, and TeO₃ units with increasing Sb₂O₃ content. XRD results reveal the presence of three crystalline: γ-TeO₂, α-TeO₂, and SbTe₃O₈ phases during the crystallization process. The density of glasses has been measured. The investigation in the ternary system by the solid state reaction using XRD reveals the existence of a solid solution Bi_1−x Sb_1−x Te_2x O₄ isotopic to BiSbO₄ with 0 ≤ x ≤ 0.1.     

Sintering and final properties of kaolinite-magnesite tapes for the manufacture of cordierite-mullite ceramics

The present work aims at studying the effect of the sintering temperature and magnesite addition on the structure and final properties of silicate ceramics tapes. A kaolinitic clay from Algeria was selected and mixed with different magnesite contents (≤12 mass%). Tape casting process was used to produce the green tapes in an aqueous system with optimized amount of surfactants. The green tapes were fired from 1000°C to 1200°C using a dwelling time of 30 minutes. The effect of the dwelling time was investigated for a firing temperature of 1200°C namely: 30 minutes, 1 hour 30 minutes and 3 hours for samples with 6 and 12 mass% of magnesite. Regarding firing conditions, crystalline phases, thermal conductivity, porosity, and flexural strength were analyzed. The results showed that increasing the sintering temperature to 1200°C tended to significantly decrease the total porosity of samples, which led to the improvement of the stress to rupture values. Specimens with 6 and 12 mass% sintered during 3 hours exhibited highest stress to rupture values (≈117 MPa) and lowest thermal conductivity (<0.2 W.m⁻¹.K⁻¹) and moderate open porosity (27%). The as-obtained ceramics appeared promising for further utilization in refractory industry, thanks to the presence of both cordierite and mullite phases.     

Antimicrobial resistance of Listeria monocytogenes isolated from dairy-based food products

In this study Listeria monocytogenes (L. monocytogenes) was isolated from three traditionally consumed Lebanese dairy-based food products. One hundred and sixty four samples (45 samples of Baladi cheese, 36 samples of Shankleesh and 83 of Kishk) were collected from the Bekaa Valley in the Northeast region of Lebanon. Suspected Listeria colonies were selected and initially identified by using standard biochemical tests. Initial identification of the positive L. monocytogenes colonies was confirmed at the molecular level by Polymerase Chain Reaction (n = 30) and the confirmed isolates were evaluated for their susceptibility to 10 commonly used antimicrobials. All of the 30 isolates were confirmed to be L. monocytogenes yielding a PCR product of ∼ 660 base pairs (bp). L. monocytogenes was detected in 26.67%, 13.89% and 7.23% of the Baladi cheese, Shankleesh and Kishk samples, respectively. The highest resistance in L. monocytogenes isolates was noted against oxacillin (93.33%) followed by penicillin (90%). The results provide an indication of the contamination levels of dairy-based foods in Lebanon and highlight the emergence of multi-drug resistant Listeria in the environment.     

Assessment of cadmium levels in human breast milk and the affecting factors: A systematic review, 1971–2014

Background: This is a first systematic review summarizing 43 years of research from 36 countries for the assessment of cadmium in breast milk, a suitable matrix in human biomonitoring. Objectives: To report from the published literature the levels of cadmium in breast milk, and the affecting factors causing increase in cadmium concentrations. In addition, to gather several quantitative data that might be useful to evaluate the international degrees of maternal and infant exposure. Methods: We reviewed the literature published between 1971 and 2014, available on Pubmed, Science Direct, and Google Scholar, reporting quantitative data about cadmium levels in human breast milk. Information about the aim of the study, name of the country, period of collection of samples, size of samples, sampling method, time of lactation, mother's age, area of residence, cadmium concentration, and other data were extracted. Results: Sixty-seven studies were selected and included in this systematic review. Some concentrations greatly exceed the limit set by the World Health Organization (WHO); however, about 50% of the studies had less than 1 µg/L cadmium concentration (recommended by the WHO); as well as many factors have shown their implication in breast milk contamination. Conclusions: Breast milk is a pathway of maternal excretion of cadmium. It is also a biological indicator of the degree of environmental pollution and cadmium exposure of the lactating woman and the nourished infant. Therefore, preventive measures and continuous monitoring are necessary.     

Selection of substrate manufacturing techniques of polyamine-based thin-film composite membranes for forward osmosis process

This paper is a comparative study on the preparation techniques used to make the support layer of polyamide-thin-film composite forward osmosis (TFC-FO) membranes. The role played by the support layer preparation technique in membrane performance is thoroughly investigated in this study. Electrospinning is shown to produce membranes of lower structural parameter compared to those obtained by conventional phase inversion techniques. The electrospun polyamide selective layer can also be tailored with the required properties. This makes electrospinning a promising process to design efficient FO membrane substrates. It is shown in this work that the FO water flux is more dependent on the internal structure of the support layer than the preparation materials. The main challenge remaining for substrates to operate in FO is to achieve simultaneously a low structural parameter, a high surface porosity, and the required mechanical properties. As most of today's approaches are not suitable, further materials development is essential in future investigations on TFC-FO membranes.     

Microwave-assisted synthesis of prebiotic di-D-fructose dianhydride-enriched caramels

The synthesis of prebiotic caramels involving the use of microwaves as the activating/heating source has been achieved. The yields in di-fructose dianhydrides (DFAs) in caramels were measured. The aim of this study was twofold: first to check the feasibility of the process, and second to determine the conditions to obtain an optimum response with microwave heating. The study showed that it was possible to obtain a yield of almost 50% of DFAs in a reaction time that was 10 times shorter than a previous study; i.e. 5–10 min for microwave activation compared to 60–120 min for conventional heating. It was shown that the radiation time and the radiation power were linked. The simultaneous determination of the values of these two factors was therefore necessary to obtain significant yields. This technique demonstrates the advantage of activation for mixtures such as caramels.     

Supramolecular Soft Adhesive Materials

The rheological and adhesive properties of bis‐urea functionalized low‐molecular‐weight polyisobutylenes (PIBUT) are investigated. The polymers, which can interact through supramolecular hydrogen bonds, can self‐organize over times of the order of days at room temperature. This organized structure has been identified by small angle X‐ray scattering (SAXS) and its rheological properties indicate the behaviour of a soft viscoelastic gel. The ordered structure can be disrupted by temperature and shear so that at 80 °C, the material behaves as a highly viscoelastic fluid and no SAXS peak is observed. When cooled back at room temperature, the PIBUT retrieves its ordered structure and gel properties after 20 h of annealing. This very slow molecular dynamics gives PIBUT a highly dissipative nature upon deformation, which combined with strongly interacting moieties results in very interesting adhesive properties both on steel surfaces but more importantly on typical low adhesion surfaces such as silicone. A strategy based on the controlled incorporation of supramolecular bonds in a covalently crosslinked network appears promising for the development of a new generation of highly interacting and dissipative soft adhesives.     

ON/OFF Markov Model Based Energy-Delay Aware MAC Protocol for Wireless Sensor Network

Today, the Wireless Sensor Networks (WSNs) are increasingly used in many applications, and in parallel the scientific researches to improve the features of such networks are accelerated. As the nodes are small components that suffer from very limited energy resources, several researches carried out at the MAC layer in order to minimize energy costs. The techniques based on periodic active/passive mode are energy efficient, but the node can not adapt the behavior of the transceiver according to the network traffic. Our approach aims to reduce the latency without increasing energy consumption. We propose to manage the radio in a dynamic way according to ON/OFF Markov model. The passage from passive to active mode is set according to the transition probability from OFF to ON state. Based on this probability, we give the period that the transceiver can stay in sleep mode. Through simulation we show that the proposed technique outperforms the well known MAC protocol for WSN.     

Genomics of Endometriosis: From Genome Wide Association Studies to Exome Sequencing

This review aims at better understanding the genetics of endometriosis. Endometriosis is a frequent feminine disease, affecting up to 10% of women, and characterized by pain and infertility. In the most accepted hypothesis, endometriosis is caused by the implantation of uterine tissue at ectopic abdominal places, originating from retrograde menses. Despite the obvious genetic complexity of the disease, analysis of sibs has allowed heritability estimation of endometriosis at ~50%. From 2010, large Genome Wide Association Studies (GWAS), aimed at identifying the genes and loci underlying this genetic determinism. Some of these loci were confirmed in other populations and replication studies, some new loci were also found through meta-analyses using pooled samples. For two loci on chromosomes 1 (near CCD42) and chromosome 9 (near CDKN2A), functional explanations of the SNP (Single Nucleotide Polymorphism) effects have been more thoroughly studied. While a handful of chromosome regions and genes have clearly been identified and statistically demonstrated as at-risk for the disease, only a small part of the heritability is explained (missing heritability). Some attempts of exome sequencing started to identify additional genes from families or populations, but are still scarce. The solution may reside inside a combined effort: increasing the size of the GWAS designs, better categorize the clinical forms of the disease before analyzing genome-wide polymorphisms, and generalizing exome sequencing ventures. We try here to provide a vision of what we have and what we should obtain to completely elucidate the genetics of this complex disease.