No abstract

We successfully prepared Au nanoparticles using the modified polyol methods and design of experiments. The desirable crystal structure and particle size of Au nanoparticles with various kinds of polyhedral and spherical shapes as well as various kinds of their morphologies or complete and rough spherical crystal surfaces were experimentally predicted in TEM and XRD measurements according to the theoretical calculation and data. The fine crystal formation of Au nanostructures by modified polyol methods with EG, PVP, and NaBH4 is of great importance to their practical applications. Our research shows that the critical nucleation, growth, and formation of sizes, shapes, and morphologies of Au nanoparticles were experimentally discussed in modified polyol methods and design of experiments. In this context, our particle size calculation can hold the greatest attraction for researchers in the field of nanoparticles.

<p>The mechanism of the dimerization of HNCO was investigated using the ab initio method. The barrier heights, reaction energies and geometrical parameters of the reactants, products, intermediates and transition state were studied. It was found that there are possibly three reaction channels. The B3LYP 6-311++G(3df,2p)//CCSD(T) 6-311++G(d,p) calculated barriers show that reaction of  formation of four-membered ring O=CNHNHC=O is more favorable than formations of CO₂ or CO. The reaction pathway of the formation of carbon monoxide from the dimerization of isocyanic acid is a new pathway. Its rate constant is very small, k = 2.62´ 10^-19 cm³/molecule/s at 2500K, 1atm, which  is about 2000 times as small as rate constant of formation CO from a bimolecular mechanism of HNCO with Ar.</p>

Environments with temperatures from 50°C to 80°C are rare in nature and are almost exclusively associated with geothermal regions including hot springs, solar-heated soils and volcanic areas. Thermophilic bacteria already exist and prefer in such habitats. Since innate tolerance to thermal environment and potential chassis for extracellular enzymes such as lipase, protease and amylase, which are utilized widely in the industrial fermentation, thermophilic bacteria have been becoming one of the objects for microbiologists worldwide, recently. This study aimed to isolate and identify thermophilic bacteria from hot springs in several provinces in Vietnam such as Ba Ria - Vung Tau and Khanh Hoa. In the results, six moderate thermophilic bacterial strains (namely BM7, BS5, NS1, NS3, NS4, and NW6) that could grow at 55oC were purified from the hot spring ecosystems. All micro morphology of isolates were recorded as rod-shaped, Gram positive, and endospore forming. The results of 16S rDNA sequencing and phylogenetic analysis showed that these isolate belonged to group I of Bacillus genus (the thermophilic group). The isolated strains NS1, NS3, NS4, BS5, NW6 and BM7 were identified to belong to the Bacillus genus, species as Bacillus sp. Resulting strains are potential candidates for industrial applications due to its stable fitness in a hash environment, particularly at high temperature. In addition, this study provides a useful insight into the diverse community of thermophilic bacteria (Bacillus spp.) in several hot springs of Vietnam, that can be applied as bacterial cell factories to produce biomaterials, biofuels, or valuable compounds in the future.

The PEG-coated iron oxide nanoparticles (Fe3O4 NPs-PEG) was synthesized by coprecipitation and ultrasonication method. X-ray diffraction results exhibited that the average size of Fe3O4 NPs-PEG was 19.10 nm, which was further confirmed in TEM imaging. In addition, sonication time and curcumin concentration were studied to evaluate the efficiency of loading curcumin onto Fe3O4 NPs-PEG. Further, statistical optimization using response surface methodology (RSM) has shown curcumin concentration (0,01% w/v) and sonication time (21 min) for maximal curcumin loading (0.37 mg/g). Along with the magnetization studies, the immobilization of curcumin onto the Fe3O4 NPs-PEG was characterized by UV, FTIR and SEM. The results showed that the curcumin loaded PEG coated iron oxide nanoparticles could potentially be used for magnetically target drug delivery.