Nano-sized Cu/Zn-modified MCM-41 (Cu/Zn-MCM-41): preparation,characterization and catalytic application in a new more atom efficient synthesis of tetrasubstituted imidazoles

The nano-sized copper/zinc-modified MCM-41 (Cu/Zn-MCM-41) was successfully prepared, characterized and applied as a new heterogeneous mesoporous and reusable nano-catalyst in a more atom efficient and novel one-pot three component strategy for the synthesis of tetrasubstituted imidazoles from nitriles, amines and benzoins under microwave irradiation. Using this method, the major problem of previously reported method (application of toxic and non-recoverable trifluoroacetic acid (TFA) as a catalyst) have been solved and all obtained results were highly similar (reaction times and yields) to the application of TFA that proved the efficiency of prepared catalyst in titled reaction.     

The use of Artificial Neural Network models for CO2 capture plants

Artificial Neural Networks (ANN) are multifaceted tools that can be used to model and predict various complex and highly non-linear processes. This paper presents the development and validation of an ANN model of a CO₂ capture plant. An evaluation of the concept is made of the usefulness of the ANN model as well as a discussion of its feasibility for further integration into a conventional heat and mass balance programme. It is shown that the trained ANN model can reproduce the results of a rigorous process simulator in fraction of the simulation time. A multilayer feed-forward form of Artificial Neural Network was used to capture and model the non-linear relationship between inputs and outputs of the CO₂ capture process. The data used for training and validation of the ANN were obtained using the process simulator CO2SIM. The ANN model was trained by performing fully automatic batch simulations using CO2SIM over the entire range of actual operation for an amine based absorption plant. The trained model was then used for finding the optimum operation for the example plant with respect to lowest possible specific steam duty and maximum CO₂ capture rate. Two different algorithms have been used and compared for the training of the ANN and a sensitivity analysis was carried out to find the minimum number of input parameters needed while maintaining sufficient accuracy of the model. The reproducibility shows error less than 0.2% for the closed loop absorber/desorber plant. The results of this study show that trained ANN models are very useful for fast simulation of complex steady state process with high reproducibility of the rigorous model.     

Formation of Nano/Ultrafine Grains in AISI 321 Stainless Steel Using Advanced Thermo-Mechanical Process

Production of nano/ultrafine grains through deformation-induced martensite formation and its reversion to austenite in an AISI 321 stainless steel was studied.The repetitive cold rolling and subsequent annealing were conducted to obtain nanocrystalline structure.Heavy cold rolling(90% reduction) at ?20 and-20 °C was carried out to induce the formation of a9-martensite from metastable austenitic material.The process was followed by annealing treatment at700–900 °C for 0.5–30 min.Effects of process parameters,i.e.,‘‘reduction percentage,' ‘‘rolling temperature,' ‘‘annealing temperature' and ‘‘annealing time',on the microstructural development were considered.Microstructural evolutions were conducted using feritscope,X-ray diffractometer and scanning electron microscope.Hardness of the specimens was measured by Vickers method.Results revealed that the higher thickness reduction and lower rolling temperature provided more martensite volume fraction and further hardness.X-ray diffraction patterns and feritoscopic results indicated that saturated strain(es) was reduced from 2.3 to 0.9 when temperature declined from ?20 to-20 °C.The smallest grain size(about 70 nm) was achieved in the condition of cold rolling at-20 °C followed by annealing at 750 °C for 5 min.     

Microstructure Modification of Powder Compact of Al-Zn-Mg Nanostructured Alloy by a Semisolid Thermomechanical Processing

A thermomechanical process(TMP) consisting of three cycles of cold pressing at 154 MPa and liquid-phase sintering at 600 ℃ for 30 min in each cycle was applied to modify the microstructure of nanostructured Al-Zn-Mg alloy.The alloy powders were produced by mechanical alloying.Also,solid-state sintering at 550 ℃ for 90 min was done to compare the results with those obtained from the TMP.The powders and the thermomechanically(TM) processed samples were analyzed by XRD to reveal the present phases in addition to calculating the crystallite size changes by the Williamson-Hall method.Moreover,scanning electron microscope was employed to observe the morphology of the powder and the microstructures of the sintered and the TM processed samples.The results revealed that the TMP affected the microstructure noticeably as well as the microhardness by removing the continuous grain boundary porosities and uniform distribution of the intermetallic phase particles as well as obtaining a near globular microstructure after the second cycle.Also,the average grain sizes in the first and the second cycles of the TMP were lower than those of the sintered sample.Furthermore,nanocrystalline grains were stable up to the second cycle of the TMP.     

SiO2–PbO–CaO–ZrO2–TiO2–(B2O3–K2O), A New Zirconolite Glass–Ceramic System: Crystallization Behavior and Microstructure Evaluation

Zirconolite (CaZrTi₂O₇) is a mineral that has a high containment capacity for actinides and lanthanides and is considered to be a good candidate for the immobilization of radioactive wastes. The glass–ceramic technique seems to be a very suitable and convenient method to produce zirconolite crystals by precipitating them in a specific glass matrix. In this study, development of a new zirconolite-based glass–ceramic belonging to SiO₂–PbO–CaO–ZrO₂–TiO₂–(B₂O₃–K₂O) system was investigated. The presence of PbO, together with B₂O₃ and K₂O, allowed the preparation of a X-ray diffraction (XRD) amorphous glass with a relatively high concentration of ZrO₂ and TiO₂, which was successfully converted to a glass–ceramic containing 34 wt% of zirconolite after heating at 770°C for 4 h. Differential thermal analysis, XRD, scanning electron microscope, and energy dispersive X-ray spectroscopy were used to determine the crystallization conditions, identify the crystallized phases, determine their compositions and quantities and observe and analyze the microstructures. The zirconolite crystals showed a platelet morphology with a monoclinic structure characterized by a =1.246 nm, b =0.7193 nm, c =1.128 nm, and β=100.508°.     

Effects induced by gamma irradiation on free‐volumes,mechanical, and thermal properties of flame‐ and non flame‐retardant polyvinylchloride

Flame‐retardant polyvinylchloride (FRPVC),typically used in cable insulation and jacketing construction for multi‐purpose reactor (MPR) at Atomic Energy Authority of Egypt, as well as carbon‐black FRPVC (CB‐FRPVC) and nonflame‐retardant PVC and CB‐PVC materials produced by Egyptian Electrical Cable Company (EECC), have been irradiated up to 160 KGy, at room temperature with a ⁶⁰Co gamma source. Free‐volumes and thermal stability of irradiated and nonirradiated PVC samples have been examined using positron annihilation Lifetime Spectroscopy (PALS) and thermogravimetric analysis (TGA). In addition, the mechanical properties: tensile strength and elongation at break were examined. Considerable presence of flame‐retardant and carbon black additives in CB‐FRPVC sample led to both quenching and inhibition of Ps formation. The mechanical and thermal characterization showed that irradiation of PVC samples up to 80 KGy effectively induced cross‐linking to maxima. Higher doses then after results in degradation and thus a decrease in mechanical strength. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and Morphological Study of Nanoparticles Ag/TiO2 Ceramic and Bactericidal Investigation of Polypropylene-Ag/TiO2 Composite

Antibacterial ceramic consisting silver nanoparticles in TiO₂ (rutile phase) particles were prepared via the chemical deposition route. Structure of synthesized ceramic was characterized using different methods of spectroscopies including; X-ray diffraction (XRD), TEM, and scanning probe microscopy (SPM). The results show that very fine silver particles were loaded on the titania dispersedly and also no crystalline change happened in the TiO₂ structure. In order to preparation of antibacterial composite, ceramic was compounded into polypropylene using a Hakke internal mixer in optimized conditions. Morphology of composite was confirmed by AFM images. Finally, antibacterial activity of composite was studied against Staphylococcus aureus. Results show that the bactericidal effect of this composite is significant and suggesting the composite to be promising candidate for applications in fields.     

Bioactivities of Achillea millefolium Essential Oil and Its Main Terpenes from Iran

Achillea millefolium L. comprises several relevant species for the food, cosmetic, perfumery, and pharmaceutical industries. Gas chromatography/mass spectrometry analysis revealed borneol to be a major component of A. millefolium, with its contribution to the essential oil being 36.35%. Borneol exhibited significant lipid peroxidation inhibition and antimicrobial activity against all tested bacterial strains. In addition, borneol had the highest antioxidant activity in all conducted assays. The borneol had significantly greater radical scavenging activity than other component essential oil and the reference antioxidant Trolox. In addition, a correlation between antioxidant activity and the total phenolic content was found. The borneol significantly inhibited nitric oxide production in lipopolysaccharide-activated macrophages (an in vitro model of inflammation). These results clearly show the antimicrobial, antioxidant, and anti-inflammatory effects of the plant essential oils.     

Immune analysis of cry1Ab-genetically modified potato by in-silico analysis and animal model

Food Science and Biotechnology - The safety of feeding transgenic potato (Solanum tuberosum), resistant to the potato tuber moth, to Wistar rats was examined from an immunological perspective. The...