The role of matching thickness on the wideband electromagnetic wave suppresser using single layer doped barium ferrite

The effect of Mg²⁺, Co²⁺and Ti⁴⁺ substitution on microwave absorption has been studied for BaMg_0.5Co_0.5Ti_1.0Fe₁₀O₁₉ ferrite-acrylic resin composite in frequency range from 13 to 20 GHz. X-ray diffraction (XRD), scanning electron microscopy (SEM), vector network analysis and vibrating sample magnetometry (VSM) were employed to analyze structure, electromagnetic and microwave absorption properties of prepared ferrite. The obtained results of reflectivity demonstrate that by varying matching thickness along with weight percentage of ferrite to acrylic resin, the bandwidth coupled with reflection loss values of prepared composites can be easily tuned. Based on microwave measurement on reflectivity, it is found that BaMg_0.5Co_0.5Ti_1.0Fe₁₀O₁₉ is a good candidate for wideband electromagnetic compatibility and other practical applications at high frequency.     

Production of single-walled carbon nanotubes from methane over Co-Mo/MgO nanocatalyst:A comparative study of fixed and fluidized bed reactors

In this study,the performances of fixed and fluidized bed reactors in the production of single-walled carbon nanotubes(SWNTs)have been investigated.In both reactors,single-walled carbon nanotubes were grown by catalytic chemical vapor decomposition(CCVD)of methane over Co-Mo/MgO nanocatalyst under two different operating conditions.The synthesized samples were characterized by TEM,TGA and Raman spectroscopy.It is found that the performance of a fluidized bed in the synthesis of carbon nanotubes is much better than that of a fixed bed.The quality of carbon nanotubes obtained from the fluidized bed was significantly higher than that from the fixed bed and the former one with the ID/IG ratio of 0.11 while the latter one with the ID/IG ratio of 0.71.Also,the yield of SWNTs in the fluidized bed was 92 wt%,while it was 78 wt%in the fixed bed.These advantages of fluidized bed reactors for the synthesis of carbon nanotubes can be attributed to more available space for the growth of carbon nanotubes and more uniform temperature and concentration profiles.     

Comparative photodynamic evaluation of new phenothiazinium derivatives against Propionibacterium acnes

The screening of recently patented derivatives of the standard phenothiazinium agents methylene blue and toluidine blue was carried out against Propionibacterium acnes, the main bacterium associated with acne vulgaris. Comparative tests were made using the topical agent benzoyl peroxide (BPO) and standard tetracyclines. Each of the photosensitizers employed, including the lead compounds, was photobactericidal at lower concentrations than BPO, and produced a much more rapid kill than the tetracyclines. In addition, the tetracyclic and pentacyclic phenothiazinium derivatives exhibited high light:dark kill ratios, suggesting that these examples might be particularly useful in practice.