Results 1 - 10 of 157926
Results 1 - 10 of 157926. Search took: 0.061 seconds
|Sort by: date | relevance|
[en] The ternary Laves phases ScTaFe and ScInCo were synthesized by arc-melting appropriate amounts of the binary phases ScFe and TaFe or Sc, In and Co, respectively. The samples were studied by powder X-ray diffraction and the structures were refined from single crystal X-ray diffraction data: P6/mmc , a=484.96(7), c=793.17(11) pm, wR 2=0.0604, 147 F values, 12 variables for ScTaFe and P6mc , a=488.61(4), c=1599.54(12) pm, wR 2=0.0389, 553 F values, 35 variables for ScInCo. ScTaFe derives from the MgZn type having a mixed Sc/Ta occupancy on the 4f magnesium position. ScInCocrystallizes with a new structure type which derives from the Laves phase MgNi. A translationengleiche symmetry reduction leads to the non-centrosymmetric space group P6mc which allows partial Sc/In ordering with different Sc/In ratios on four crystallographically independent sites. While ScFe and TaFe build a complete solid solution ScTaFe with MgZn type structure, we observe a switch in structure type for ScInCo from the cubic MgCu type (x=0-0.22) to the non-centrosymmetric derivative from MgNi at x=0.37. (© 2020 The Authors. Zeitschrift für anorganische und allgemeine Chemie published by Wiley-VCH GmbH)
[en] A sponge rubber nanocomposite based on styrene–butadiene rubber (SBR)/nanoclay (montmorillonite, MMT) or nano-calcium carbonate (CaCO) fillers with various foaming agent contents was produced by a simple technique, roll milling. The nanoparticles were examined by different techniques, such as X-ray fluorescence (XRF), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), and Fourier-transform infrared (FT–IR). The sponge rubber nanocomposites were characterized by scanning electron microscopy (SEM) image analysis before and after exposures to radiation doses, as well as by the XRD patterns for the unirradiated samples. The different properties of the obtained nanocomposites, including their foaming degree, tensile strength, elongation at break, and thermal conductivity, were also investigated. The foam composites containing nano-CaCO possessed the best cell and crosslinking densities and mechanical properties among the other composites, while its foaming degree was the lowest. The results indicated that the thermal conductivity was reduced by increasing the foaming agent concentration. However, it increased as the radiation dose increased, and the optimum radiation dose was obtained at 75 kGy. The foam containing MMT exhibited an intermediate behavior while high thermal conductivity was recorded for the foam containing the CaCO nanoparticles.
[en] Senna alexandrina Mill leaves are widely used in traditional medicine for its pharmacological properties. The present study was designed to evaluate antifungal activities of solvent extracts from S. alexandrina leaves against human and phytopathogenic fungi, including plant pathogens, Alternaria alternata, Fusarium monoliforme, F. oxypsporum, F. solani and Helminthosporium sativum, and human pathogens, Candidia albicans, C. famata, C. krusei, and C. parapsilosis. Poisoned food and agar well diffusion methods were used to assess antifungal activity. Acetone, methanol and aqueous extracts were prepared and screened; methanol and aqueous extracts were effective in inhibiting the growth of some phytopathogens. However, Candida spp were resistant towards all solvent extracts. Maximum growth inhibition was observed with methanol and aqueous extracts for Fusarium monoliforme (85%) and F. solani (76%) at a concentration of 0.5 mg/mL. Minimum inhibitory concentration (MIC) and minimum fungicidal concentrations (MFC) ranged between 1–128 mg/mL. Scanning and transmission electron microscopy (SEM and TEM) of fungal isolates at MIC concentrations revealed severe damage to cell morphology and ultrastructure. Distorted and shriveled hyphae as well as peeled and damaged conidia were evident in SEM microphotographs. Similarly, TEM microphotographs showed underdeveloped cells, shrunken cytoplasm, membrane bulging and membranes absence. Fourier-transform infrared spectroscopic analysis of methanol and aqueous extracts showed the presence of important functional groups, including phenols, alcohols, aromatic compounds, and flavonoids. Senna alexandrina leaf extracts can serve as a useful alternative to harmful fungicides for control of plant pathogens. (author)
[en] After having evoked the context (commitments related to the Paris Agreement, ecological transition, objective of carbon neutrality, reduction of the dependence of industry on fossil energies, use of decarbonized inputs to produce heat, and necessary development and deployment of new processes and also new technologies for CO2 capture, storage and valorization); this contribution proposes a critical discussion of the exploitation of hydrogen combustion, of its strengths and weaknesses, of its scientific and technological locks. Then, it discusses the exploitation of the combustion of hydrogen-natural gas mixtures (Hythane): production, strengths and weaknesses, benefits of such a combustion (due to energy properties of natural gas, to energy storage and transport, to CO2 emission reduction). It addresses the case of ammoniac combustion: NH3 production, use as fuel or energy vector, scientific and technological locks.
[en] Two articles comment the emergence of several technologies and demonstrators for the capture of CO2 where it is highly concentrated: in industrial smokes. A first article evokes projects and demonstrators based on the use of liquid solvents (a technology which is more advanced than the others), on kinetic and chemical innovations, on the emergence of the use of solid sorbents, on the potential of membranes and cryogenics. It also evokes another possibility: the modification of industrial processes for an easier or more efficient CO2 capture. The second article briefly evokes technologies of CO2 capture directly in the air which have now reached the industrial stage, but without having actually demonstrated their benefit for the climate
[en] The current work focused on green synthesis of Zinc nanoparticles (ZnNPs) using the aqueous extract of Brassica oleracea italica inflorescence acting as a reducing agent. The characterization of ZnNPs was done by UV visible spectrophotometer for confirmation of the zinc nanoparticles formation. Other techniques were also done including SEM for morphology, XRD for crystalline structure, EDX for elemental analysis, FTIR for functional groups determination and TGA for mass analysis. Spherical shape nanoparticles were found with size ranging between 100-500nm by SEM analysis. From analysis of TGA it was elucidated that the compound is thermally sensitive to temperature as weight reduction was observed with rise in temperature. The ZnNPs showed low activity against Shigella dysenteria, while a good antifungal activity was found against Paeciolmyces fulvus (70%). Positive results were achieved against blood groups O+, O-, AB- and B- while performing the haemagglutination activity. In phytotoxic activity, more damaged plants were observed at low concentration of ZnNPs. From the above study, it is concluded that the selected plant can be used for nanoparticles synthesis for achieving good antifungal, haemagglutination and phytotoxic effects. (author)
[en] The extraction behavior of several lanthanide ions (La(III), Nd(III), Sm(III), Gd(III), Yb(III)) from the nitric acid medium using ionic liquid [C4mim][NTf2] solvent containing N,N'-dimethyl-N,N'-dioctyl-3-oxadiglycolamide (DMDODGA) was studied. The effects of the concentration of HNO3, H+ and NO3- in aqueous phase, as well as the DMDODGA concentration and temperature on the distribution ratio of Ln(III) were analyzed. The distribution ratio of lanthanide ions into [C4mim][NTf2] is much higher than that reported for aliphatic hydrocarbon diluents. The extraction mechanism was demonstrated to agree with the cation-exchange mechanism. The stoichiometric ratio of Ln (III)/DMDODGA complex is 1:3 or 1:4. (author)
[en] Heating and cooling are two important procedures in manufacturing as well as transportation industries.Rather than the conventional fluids, solutions of fluids with metal nanoparticles have higher thermal conductivity for effective cooling. Therefore, present paper is a comparative study of squeezing flow analysis of copper oxide–water and oil (kerosene)-based nanofluid between two parallel plates. Magnetohydrodynamic flow of kerosene-based nanofluid along with the dissipative heat energy may enhance the thermal properties of the fluid. Assuming self-similar variables, the governing equations get transformed into non-dimensional forms and approximate analytical techniques such as variation parameter method is employed for these transformed equations. With the well posed physical parameters, the computation is carried out using the mathematical package MATHEMATICA and displayed via graphs and numerical results are shown in tabular form. Favourable cases in comparison with earlier studies are also studied wherever possible. However, when the plates are away from each other, it is seen that the kerosene-based nanofluid velocity overrides the water-based nanofluid whereas the impact is reversed in the case of squeezing.(author)
[en] A three-dimensional (3D) activated framework carbon (3D AFC) was prepared in our research group and applied to adsorb U(VI) from radioactive waste water. Meanwhile, The effects of solid–liquid ratio, contact time, pH value, ionic strength and ionic concentration of adsorbate on the adsorption of U(VI) by the 3D AFC were studied. The calculated maximum adsorption capacity of 3D AFC was 127.5 mg/g under the condition that pH was 5.8. Combined with the properties of excellent three-dimensional network structure, simple synthesis methodology, and the adsorption capacity for U(VI), 3D AFC is considered to be feasible for recycling U(VI) from waste water solutions. (author)
[en] The work focuses on the removal of Arsenic-III (As(III)) from water sample by an indigenous iron ore from Balochistan by adsorption method. Three iron ore samples were analyzed by X-Ray Diffractometer (XRD) and a sample from Shikarap containing iron 36.2% was selected because it contained the highest amount of hematite. The batch study was conducted to examine the adsorption by iron ore and maximum adsorption was observed at pH 6, 1/2 g dose per 50 mL solution, contact time 2 hr and shaking speed 150 rpm. At the optimized conditions, the removal was 89% when monitored at 50 μg L-1 initial concentration of arsenic. The arsenic removal was monitored by Atomic Absorption Spectrometer (AAS) using hydride generation. Dubinin - Radushkevich (D-R), Freundlich and Langmuir's isotherms were examined. The highest adsorption capacity of iron ore for As(III) removal was observed 13.67 μg g-1 by Langmuir model and Freundlich isotherm indicated good adsorption intensity with value n = 1.512. Thermodynamic parameters revealed that adsorption was exothermic and physisorption. The Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray (EDX techniques were applied to scan the surface morphology and the percentage elemental composition of samples respectively. SEM results demonstrated that Shikarap mineral grains are an oval shape and these were changed after the uptake of As(III). The EDX spectra of Shikarap mineral confirm the As(III) adsorption on particles as As 4.19%. (author)