Microwave‐assisted Chemical Reactions

Microwave (MW) radiation has been used in chemical analysis and chemical synthesis. MW heating under controlled conditions offers distinct advantages over conventional heating. The reactions are carried out in environmentally clean and safe solvents and in many cases, reactions can be carried out under solvent‐free conditions. This method of synthesis has grown rapidly and found its use in various sectors. This paper reviews some of the reactions that have been accelerated with higher yields under MW irradiation. The application of MW‐assisted synthesis in the medicinal and pharmaceutical industries will be emphasized.     

Influence of the physico-chemical properties of Selangor soil series on the distribution coefficient (<Emphasis Type="Italic">K</Emphasis><Subscript>d</Subscript>-value) of <Superscript>226</Superscript>Ra

²²⁶Ra is a member of the ²³⁸U natural decay series and is one of the most important isotope to be determined among the naturally occurring nuclides in environmental samples. In order to evaluate the radiation dose from ²²⁶Ra, it is important to know its mobility in different types of soils. The aim of the present study is to quantify the influence of physico-chemical soil properties on ²²⁶Ra adsorption. The distribution coefficients (K _d-value) of ²²⁶Ra in Selangor soil series samples were measured in one core, at three depth levels to evaluate the adsorbability of ²²⁶Ra. The soil samples were spiked with ²²⁶Ra tracer and the activities of ²²⁶Ra in the separated phase from batch sorption test were measured by a low background but high efficiency well-type HPGe detector. Several physico-chemical soil properties were also characterised for each soil samples. Pearson’s correlation and stepwise multiple regression test were applied at the 0.05 level of significance throughout all analysis to determine the relationships and influences between distribution coefficients (K _d-value) of ²²⁶Ra with physicochemical soil properties for the Selangor soil series. The observed K _d value was in the range of 50.55–172.28 mL g⁻¹ (mean: 93.20 ± 46.99 mL g⁻¹). The regression showed that the highest positive correlations were observed for organic matter (OM) and cation exchange capacity (CEC) (r = 0.96**, 0.81**, respectively) with K _d-values. The results indicate that the stepwise multiple regression model incorporating the soil’s OM and CEC accounts for 98% of the variability in distribution coefficients of ²²⁶Ra.     

Effective electrodeposition of Co-Ni-Cu alloys nanoparticles in the presence of alkyl polyglucoside surfactant

The effect of alkyl polyglucoside (APG) surfactant on the electrodeposition Co-Ni-Cu alloys nanoparticles has been investigated. In a typical electrodeposition experiment, it was found that as prepared Co-Ni-Cu alloys nanoparticles characteristics, such as size homogeneity, density, dispersion on the electrode substrate and the chemicals composition, depended strongly on the concentration of APG used in the reaction as well as the applied deposition potential. For the case of chemicals composition, low APG concentration (below CMC) was found to be effective for the preparation of excellent composition of the nanoalloys. Meanwhile, for the case of size homogeneity, density, and dispersion on the surface, high APG concentration (above CMC) and high deposition potential were preferred. It was also found that, at concentration above the CMC, the APG surfactant showed a metals ions deposition inhibition characteristic that caused increasing in the electrodeposition overpotential of the entire metals ions, namely cobalt, nickel and copper. As the result the copper was found to place a high percentage in the nanoalloys deposits. Owing to its simple procedure in controlling the composition and the nanoalloys growth characteristic, present approach should find a potential application in preparing Co-Ni-Cu magnetic nanoparticles for used in currently existing applications.     

Effect of calcination temperature on the surface morphology and crystallinity of tungsten (VI) oxide nanorods prepared using colloidal gas aphrons method

The effect of calcination temperature on the surface morphology and crystallinity of tungsten (VI) oxide, WO₃ nanorods prepared using colloidal gas aphrons (CGAs) as template was studied. The synthesized WO₃ nanorods were calcined in a furnace for 4 h at four different temperatures, i.e., 400, 500, 600 and 700 °C. The morphology of the calcined WO₃ nanorods have been characterized by both transmission electron microscope (TEM) and variable pressure scanning electron microscope (SEM) equipped with energy dispersive X-ray analysis (EDAX). The results showed that the calcination temperature influenced the shape and size of the WO₃ nanorods produced. It is also found that the calcination at various temperature do not effect the composition and the purity of the WO₃ nanorods. In order to characterize the crystalinity of WO₃, X-ray diffraction (XRD) has been used. It shows that all the calcined WO₃ produced are in crystalline form compared to the as-prepared WO₃ nanorods, which is in amorphous form.     

Tin stearate organometallic precursor prepared SnO2 quantum dots nanopowder for aqueous- and non-aqueous medium photocatalytic hydrogen gas evolution

Current study reports a rapid one-pot non-hydrolytic condition in the synthesis of Sn O₂ QDs nanopowder using tin（II） stearate（Sn（St）₂） as environmentally-benign organometallic precursor,which is an unprecedentedly employed-compound in preceding Sn O₂ nanopowder productions.The as-synthesized Sn O₂ QDs that are hydrophobic can be easily transferred from organic solvent to aqueous solution through a robust ligand exchange method.The stearate-capping ligands on the surface of QDs can be replaced by beta-cyclodextrin（β-CD） and eventually render the QDs highly water soluble,which ultimately make it exhibit bi-functionality for different liquid medium applications.Structural characterizations reveal that the bi-functional QDs are indeed well-matched with the standard rutile Sn O₂ cassiterite phase without the presence of any impurities.The QDs can be interchangeably used as photocatalyst for both aqueous and non-aqueous phase,where it shows significant enhancement of hydrogen gas production as compared to that of commercial Sn O₂ nanopowder.     

Effect of polyethylene glycol-2000 on amino acid surfactant-based vesicles

Polyethylene glycol (PEG)-modified amino acid surfactant-based vesicles were prepared to improve the stability and cellular delivery of drugs. The vesicles comprised PEG-2000, sodium N-lauroylsarcosinate hydrate (SNLS), 1-decanol, and deionized water. The complex showed vesicular structures that were almost the same as the original vesicles, and their size distribution was (100–150 nm). Transmission electron microscopy (TEM) results revealed that no fusion occurred at 1.25 wt.% PEG concentration. The steric hindrance present among the vesicles prevented aggregation of the particles. No visual phase separation was observed for 6 months at room temperature 28?ºC. At higher molar concentration of PEG, fusion and wrinkling occurred owing to the association of PEG chains. The decreasing bending curvature led to the formation of fused vesicles with multilayer structure, as revealed by TEM and differential scanning calorimetry (DSC).     

Three-Component Olive Oil-In-Water High Internal Phase Emulsions Stabilized by Palm Surfactant and Their Moisturizing Properties

In the present study, olive oil was used for the preparation of three-component high internal phase emulsions with oil volume fraction of more than 0.77 stabilized by palm-based polyoxyethylene lauryl ether for the first time. These emulsions were investigated on their morphology, structural properties, stability, and hydration efficacy. Droplet size distribution observed from the optical micrographs was in agreement with the light scattering results, which suggested that droplet size was influenced by oil phase and surfactant concentrations. Rheological results exhibiting flow curves cross-over implied structural build-up that gave rise to high stability which was supported by stable three-month storage at an elevated temperature. The hydration efficacy of the emulsion was examined in vivo using a corneometer.