The evolution of shrinkage strain of pet-mortar composite eco-materials

Concretes and mortars are subjected to several kinds of shrinkage strains which represent the volumic variations resulting from the cement hydration and are governed by various physical and chemical aspects. The use of polyethylene terephthalate PET plastic wastes which are available in quantity and within low cost in our country yields a very important economic and environmental impact in the construction industry. Thus, we are interested to investigate the effect of PET volumetric additive amounts for cement substituting and for the behavior of the total, drying and autogenous shrinkage. Comparison study of obtained experimental results with codale prediction models were performed according to Eurocode 2  (EC2) in order to analyze the evolution of shrinkage strain with PET-mortar  composite ages and for several rates of PET waste additions. According to obtained results, PET additions acts to reduce shrinkage strains of PET-mortar composites which promote the use of these modified mortar Eco-materials in the field of construction industry.Keywords: Composite Eco-materials; Cement substitution; Shrinkage strain; PET waste; EC2

Chironomid taxocenosis in a South Mediterranean wadi, the Kebir-East (Algeria)

SUMMARY - Chironomid taxocenosis in a South Mediterranean wadi, the Kebir-East (Algeria) - A total of 37 chironomid species were recorded during a survey of the catchment of the Kebir-East wadi, northeast Algeria. Chironomids spatial and temporal distributions were investigated based on 23 sampling sites, situated mainly within the El Kala National Park, across 4 seasons. Chironomid assemblages in the Kebir-East were similar to the ones known from other Mediterranean areas and were composed mostly of tolerant species (Chironomus riparius, Cricotopus (Isocladius) sylvestris), but some intolerant species (Paratrissocladius excerptus, Parakiefferiella gracillima, Thienemanniella partita) were present in some samples. A coinertia analysis was carried out to match 21 environmental variables at different spatial scales with the 37 chironomid species recorded in 90 samples: A longitudinal gradient was found along the first axis, which accounted for 42 % of the total variance; the samples ordered along the second axis, which accounted for 13 % of the total variance, were separated according to water temperature, water chemistry and site\u2019s morphometry. The influence of anthropogenic pressures was evaluated with different benthic quality indices based on species diversity and on species optima (i.e. mean value of environmental variables weighted for species abundance). Results showed that the trophic status index was influenced by water quality and habitat type (krenal, rhithral, potamal), while the biotic indices were more influenced by season. To improve knowledge on the response of intolerant species, we suggest the implementation of a regular, more intensive sampling program

A mathematical model for optimizing the indications of liver transplantation in patients with hepatocellular carcinoma

Abstract Background The criteria for organ sharing has developed a system that prioritizes liver transplantation (LT) for patients with hepatocellular carcinoma (HCC) who have the highest risk of wait-list mortality. In some countries this model allows patients only within the Milan Criteria (MC, defined by the presence of a single nodule up to 5 cm, up to three nodules none larger than 3 cm, with no evidence of extrahepatic spread or macrovascular invasion) to be evaluated for liver transplantation. This police implies that some patients with HCC slightly more advanced than those allowed by the current strict selection criteria will be excluded, even though LT for these patients might be associated with acceptable long-term outcomes. Methods We propose a mathematical approach to study the consequences of relaxing the MC for patients with HCC that do not comply with the current rules for inclusion in the transplantation candidate list. We consider overall 5-years survival rates compatible with the ones reported in the literature. We calculate the best strategy that would minimize the total mortality of the affected population, that is, the total number of people in both groups of HCC patients that die after 5 years of the implementation of the strategy, either by post-transplantation death or by death due to the basic HCC. We illustrate the above analysis with a simulation of a theoretical population of 1,500 HCC patients with tumor size exponentially. The parameter λ obtained from the literature was equal to 0.3. As the total number of patients in these real samples was 327 patients, this implied in an average size of 3.3 cm and a 95% confidence interval of [2.9; 3.7]. The total number of available livers to be grafted was assumed to be 500. Results With 1500 patients in the waiting list and 500 grafts available we simulated the total number of deaths in both transplanted and non-transplanted HCC patients after 5 years as a function of the tumor size of transplanted patients. The total number of deaths drops down monotonically with tumor size, reaching a minimum at size equals to 7 cm, increasing from thereafter. With tumor size equals to 10 cm the total mortality is equal to the 5 cm threshold of the Milan criteria. Conclusion We concluded that it is possible to include patients with tumor size up to 10 cm without increasing the total mortality of this population

Theoretical study of organic materials based on Thieno[2,3-b]thiophene as layer of bulk heterojunction solar cells

In this study, we report a theoretical investigations on the structural, optoelectronic and photovoltaic properties of a series of conjugated organic molecules containing thieno[2,3-b]thiophene, with different substituents. The DFT calculations were performed by using the quantum chemical methods using B3LYP [1] level with 6-31G(d) [2] basis set for all atoms. All calculations were realized by Gaussian 09 [3] program supported by GaussView 5.0.8 interface. Moreover, the optoelectronic properties (HOMO, LUMO, Egap…) were determined from the fully optimized structures. The absorption properties (λmax, Etr, OS) of these molecules are obtained by TD-B3LYP/6-31G(d) method [4].The studied oligomers can be subdivided in three categories; the first one constitutes by synthetized oligomers [5] but is characterized with the highest energy band values. Thanks to the effect of structural modifications in there chemical structures in the second and the third categories, the energy gap values have known a dramatic decrease. We conclude that these conjugated materials, especially of the third categories, are good candidates for bulk heterojunctions in organic solar cells applications.

Steady Flow of Purely Viscous Shear-Thinning Fluids in a 1:3 Planar Gradual Expansion

Laminar flow of non-Newtonian fluid (shear-thinning) through a 1:3 planar gradual expansion is numerically investigated, for various Power-Law index (0.6, 0.8 and 1.0) and expansion angles (15, 30, 45, 60 and 90°) at different generalized Reynolds number (1 ≤ Reg ≤ 400). The study of these parameters effect on the flow pattern allowed the determination of the two critical generalized Reynolds numbers (Regcr1 and Regcr2), which correspond to the transition from the symmetric to the asymmetric flow and the appearance of the third recirculation zone respectively. The results showed that decreasing the Power-Law index or the expansion angle stabilizes the flow by increasing significantly the two critical generalized Reynolds numbers. In order to predict the two critical generalized Reynolds numbers, two correlations have been proposed

KAT Ligation for Rapid and Facile Covalent Attachment of Biomolecules to Surfaces

The efficient and bioorthogonal chemical ligation reaction between potassium acyltrifluoroborates (KATs) and hydroxylamines (HAs) was used for the surface functionalization of a self-assembled monolayer (SAM) with biomolecules. An alkane thioether molecule with one terminal KAT group (S-KAT) was synthesized and adsorbed onto a gold surface, placing a KAT group on the top of the monolayer (KAT-SAM). As an initial test case, an aqueous solution of a hydroxylamine (HA) derivative of poly(ethylene glycol) (PEG) (HA-PEG) was added to this KAT-SAM at room temperature to perform the surface KAT ligation. Quartz crystal microbalance with dissipation (QCM-D) monitoring confirmed the rapid attachment of the PEG moiety onto the SAM. By surface characterization methods such as contact angle and ellipsometry, the attachment of PEG layer was confirmed, and covalent amide-bond formation was established by X-ray photoelectron spectroscopy (XPS). In a proof-of-concept study, the applicability of this surface KAT ligation for the attachment of biomolecules to surfaces was tested using a model protein, green fluorescent protein (GFP). A GFP was chemically modified with an HA linker to synthesize HA-GFP and added to the KAT-SAM under aqueous dilute conditions. A rapid attachment of the GFP on the surface was observed in real time by QCM-D. Despite the fact that such biomolecules have a variety of unprotected functional groups within their structures, the surface KAT ligation proceeded rapidly in a chemoselective manner. Our results demonstrate the versatility of the KAT ligation for the covalent attachment of a variety of water-soluble molecules onto SAM surfaces under dilute and biocompatible conditions to form stable, natural amide bonds

Environmental factors affecting the distribution of Chironomid larvae of the Seybouse wadi, Northeastern Algeria

A survey of the Seybouse wadi (North-Eastern Algeria) between 2008 and 2011 was conducted in 26 sampling sites located on the main river and its tributaries using chironomids. From 3264 collected larvae, forty-five chironomid species were identified, and were correlated to 13 environmental variables to predict determinant factors affecting their distribution. Indicator value (IndVal) analysis was first performed to determine indicator chironomid species according to several factors (sites, seasons, source distance, granulometry, conductivity, water temperature, dissolved oxygen, water velocity, pollution and the abundance of filamentous algae). Co-inertia analysis (CoIA) supported the IndVal results, emphasising an upstream/downstream gradient in the first axis, while a granulometry gradient was emphasised by the second axis. A pollution gradient was also highlighted in the plane of the first two axes, separating tolerant Chironomus sp. 1, Cricotopus bicinctus and Cricotopus (Isocladius) sylvestris from intolerant species as Phaenopsectra flavipes, Rheotanytarsus sp.1 and Cladotanytarsus sp. 1