Study of critical properties in B-spinel ZnxCd1-xCr2Se4 (0.35 ≤ x ≤ 0.58)

The critical behaviour of the B-spinel ZnxCd1-xCr2Se4 systems is studied in the concentration range 0.35≤x≤0.58. The mean field theory and the ferromagnetic spin-wave theory at low temperatures are combined to calculate the exchange integrals up to the third nearest neighbours. The ferromagnetic critical region is studied by the high-temperature series expansion (H.T.S.) extrapolated with the Padé (P.A) approximants method. The critical temperatures T c and the critical exponents associated with the magnetic susceptibility (γ) and the correlation length (ν) are estimated. The obtained values of T c are in good agreement with those obtained by magnetic measurements. The values of γ and ν are sensitive to the dilution ratio x. For the compounds situated in the ferromagnetic region ( 0.35≤x≤0.41), they are close to those of 3D Heisenberg model. For the compounds presenting re-entrant behaviour ( 0.41≤x≤0.58 ), γ and ν deviate slowly from those of this model and approach the values found in re-entrant systems.The critical behaviour of the B-spinel ZnxCd1-xCr2Se4 systems is studied in the concentration range 0.35≤x≤0.58. The mean field theory and the ferromagnetic spin-wave theory at low temperatures are combined to calculate the exchange integrals up to the third nearest neighbours. The ferromagnetic critical region is studied by the high-temperature series expansion (H.T.S.) extrapolated with the Padé (P.A) approximants method. The critical temperatures T c and the critical exponents associated with the magnetic susceptibility (γ) and the correlation length (ν) are estimated. The obtained values of T c are in good agreement with those obtained by magnetic measurements. The values of γ and ν are sensitive to the dilution ratio x. For the compounds situated in the ferromagnetic region ( 0.35≤x≤0.41), they are close to those of 3D Heisenberg model. For the compounds presenting re-entrant behaviour ( 0.41≤x≤0.58 ), γ and ν deviate slowly from those of this model and approach the values found in re-entrant systems

Study of Magnetic Superexchange in diluted Systems Znx Cd1-xCr2Se4 ( 0.35 ≤ x ≤ 0.58 )

The effects of cationic substitutions at different concentrations within the lattice Znx Cd1-xCr2Se4 (0.35≤x≤0.58) on the electronic transfer in chromium ions are investigated. For this propose, after taking into account the exchange integrals, we use the Anderson’s-Kanamori theory of superexchange to determine the transfer integrals bσσ and bπσ . With the use of the conventional molecular orbital model the covalency-mixing parameters, λσ and λπ, the electron spin transfer coefficients, ƒ i (i=σ, π, s ), and the total charge, C, transferred from ligand to the chromium ions, are evaluated. The variation of bσσ and bσπ with x agree with the passage of the system from ferromagnetic to antiferromagnetic order. For the compound presenting re-entrant behaviour (0.45≤x≤0.58), f s exhibits anomalous. The increasing in C with x is consistent with the expected decrease in covalency of the non magnetic cation in tetrahedral site.The effects of cationic substitutions at different concentrations within the lattice Znx Cd1-xCr2Se4 (0.35≤x≤0.58) on the electronic transfer in chromium ions are investigated. For this propose, after taking into account the exchange integrals, we use the Anderson’s-Kanamori theory of superexchange to determine the transfer integrals bσσ and bπσ . With the use of the conventional molecular orbital model the covalency-mixing parameters, λσ and λπ, the electron spin transfer coefficients, ƒ i (i=σ, π, s ), and the total charge, C, transferred from ligand to the chromium ions, are evaluated. The variation of bσσ and bσπ with x agree with the passage of the system from ferromagnetic to antiferromagnetic order. For the compound presenting re-entrant behaviour (0.45≤x≤0.58), f s exhibits anomalous. The increasing in C with x is consistent with the expected decrease in covalency of the non magnetic cation in tetrahedral site

Phenolic characterization and antioxidant activity of two endemic wormwood species of Morocco: Artemisia ifranensis J. Didier and Artemisia mesatlantica

Artemisia ifranensis and Artemisia mesatlantica are two endemic species in Morocco belonging to the Asteraceae family. Located in the region of Moroccan Atlas, they are very much sought after by the local population for their therapeutic properties.However, given the limited studies conducted on these species and in order to contribute to their valorization, we selected them in full bloom in the region of Timahdite for a phytochemical study and an evaluation of their antioxidant properties. The results of phytochemical screening revealed their richness in polyphenols, sterols, triterpenes and mucilages. The extraction yields of the total polyphenols by maceration in a methanol-water mixture (80/20) were 10.10% for A. mesatlantica and 16.66% for A. ifranensis. The determination of the total phenols by the Folin-Ciocalteu method after fractionation of the polyphenolic extracts showed the abundance of these compounds in the butanolic fraction of A. Mesatlantica and the methanolic extract of A. Ifranensis. For the total flavonoids dosed with aluminum trichloride, the ethyl acetate fractions of A. Mesatlantica and butanolic acid. Ifranensis were the richest. In addition, the crude extract of A. Mesatlantica was particularly rich in condensed tannins.Evaluation of the antioxidant activity by reduction of iron (FRAP) and trapping of the free radical DPPH * showed that all the extracts have a moderate antioxidant power.These early studies on A. mesatlantica and A. ifranensis of Timahdite reveal their abundance of important chemical compounds. Also, due to the ability of these plants to trap radicals, they can be considered as sources of natural antioxidants

Conversion of Uric Acid into Ammonium in Oil-Degrading Marine Microbial Communities: a Possible Role of Halomonads

Uric acid is a promising hydrophobic nitrogen source for biostimulation of microbial activities in oil-impacted marine environments. This study investigated metabolic processes and microbial community changes in a series of microcosms using sediment from the Mediterranean and the Red Sea amended with ammonium and uric acid. Respiration, emulsification, ammonium and protein concentration measurements suggested a rapid production of ammonium from uric acid accompanied by the development of microbial communities containing hydrocarbonoclastic bacteria after 3 weeks of incubation. About 80 % of uric acid was converted to ammonium within the first few days of the experiment. Microbial population dynamics were investigated by Ribosomal Intergenic Spacer Analysis and Illumina sequencing as well as by culture-based techniques. Resulting data indicated that strains related to Halomonas spp. converted uric acid into ammonium, which stimulated growth of microbial consortia dominated by Alcanivorax spp. and Pseudomonas spp. Several strains of Halomonas spp. were isolated on uric acid as the sole carbon source showed location specificity. These results point towards a possible role of halomonads in the conversion of uric acid to ammonium utilized by hydrocarbonoclastic bacteria

Using web and mobile phone technologies to collect food market prices in Africa. Approaching real-time data and use of crowdsourcing, 2013 - 2016

Large agricultural commodity price swings observed in recent years have made the importance of accessible, timely, accurate and frequently updated price data more obvious. This study investigates the potential of innovative web and mobile phone technologies and alternative data collection methods such as crowdsourcing in order to collect food price data in Africa. The report summarises these experiences through the lessons learned and provides a detailed overview and assessment of different aspects of the collected data that can be of help for the success of future food price collection exercises.JRC.D.4-Economics of Agricultur

(Plasticized) polylactide/clay nanocomposite textile : thermal, mechanical, shrinkage and fire properties

peer reviewedVarious quantities of Cloisite® 30B (from 1% to 4% in weight) have been added to a polylactide matrix by melt blending to produce polylactide-based nanocomposites. Then, these blends have been melt-spun to produce multifilaments yarns. It is demonstrated that it is necessary to use a plasticizer to spin a blend with 4% in weight of Cloisite® 30B. The properties of these yarns have been studied (dispersion of the clay, thermal, mechanical and shrinkage properties). A decrease of the tensile properties is observed when the quantity of Cloisite® 30B increases, but an improvement of the thermal and shrinkage properties is highlighted. These multifilaments have been knitted and the flammability studied using cone calorimeter at 35 kW/m2. A strong decrease, up to 38%, of the heat release rate has been measured

Chemoradiotherapy with or without consolidation chemotherapy using cisplatin and 5-fluorouracil in anal squamous cell carcinoma: long-term results in 31 patients

<p>Abstract</p> <p>Background</p> <p>The objectives of this study were to evaluate long-term results of concurrent chemoradiotherapy (CRT) with 5-fluorouracil and cisplatin and the potential benefit of consolidation chemotherapy in patients with anal squamous cell carcinoma (ASCC).</p> <p>Methods</p> <p>Between January 1995 and February 2006, 31 patients with ASCC were treated with CRT. Radiotherapy was administered at 45 Gy over 5 weeks, followed by a boost of 9 Gy to complete or partial responders. Chemotherapy consisted of 5-fluorouracil (750 or 1,000 mg/m²) daily on days 1 to 5 and days 29 to 33; and, cisplatin (75 or 100 mg/m²) on day 2 and day 30. Twelve patients had T3–4 disease, whereas 18 patients presented with lymphadenopathy. Twenty-one (67.7%) received consolidation chemotherapy with the same doses of 5-fluorouracil and cisplatin, repeated every 4 weeks for maximum 4 cycles.</p> <p>Results</p> <p>Nineteen patients (90.5%) completed all four courses of consolidation chemotherapy. After CRT, 28 patients showed complete responses, while 3 showed partial responses. After a median follow-up period of 72 months, the 5-year overall, disease-free, and colostomy-free survival rates were 84.7%, 82.9% and 96.6%, demonstrating that CRT with 5-fluorouracil and cisplatin yields a good outcome in terms of survival and sphincter preservation. No differences in 5-year OS and DFS rates between patients treated with CRT alone and CRT with consolidation chemotherapy was observed.</p> <p>Conclusion</p> <p>our study shows that CRT with 5-FU and cisplatin, with or without consolidation chemotherapy, was well tolerated and proved highly encouraging in terms of long-term survival and the preservation of anal function in ASCC. Further trials with a larger patient population are warranted in order to evaluate the potential role of consolidation chemotherapy.</p

MRP1 polymorphisms (T2684C, C2007T, C2012T, and C2665T) are not associated with multidrug resistance in leukemic patients

Abstract. One of the main problems in treating cancer patients is that cancer cells can develop drug resistance. Resistance to multiple anticancer drugs, so called multidrug resistance (MDR), most likely involves a nonspecific mode of resistance, through drug-efflux transporters. One of the most extensively studied genes involved in MDR is multidrug resistance protein 1 (MRP1). We investigated a possible association between the expression level of MRP1 and the occurrence of MDR in leukemic patients, and we tested the hypothesis that MRP1 polymorphisms are predictive of MDR in patients with acute leukemia. The mRNA level of MRP1 was determined in 111 patients with acute leukemia (including 52 patients with acute myeloid leukemia and 59 patients with acute lymphoblastic leukemia), by quantitative real-time PCR, to determine how it af