Optimizing Green Synthesis of Hydrotalcite - Silver Nanoparticles using Syzygium Nervosum based Reducing Agent.

Hydrotalcite-silver (HT-Ag) nanoparticles have been involved in various daily crucial applications, such as antibacterial, photocatalytic, adsorption, etc. There are many approaches to synthesizing silver nanoparticles (AgNPs) decorated on hydrotalcite (HT) surface and the most used approach is using a strong reducing agent. Thus, affordable but effective "green" reducing agents - Syzygium nervosum leaf extract, are taken into account in this work to solve several issues related to chemical reducing agents. This work aimed to assess the effect of Syzygium nervosum leaf extract as a reducing agent for green synthesis of AgNPs on HT through an optimizing process using response surface methodology (RSM) and the Box-Benken model. The optimal conditions for the synthesis of AgNPs on HT include a reaction time of 6.15 hours, a reaction temperature of 50 °C, and the ratio of diluted Syzygium nervosum leaf extract to reduce AgNO3 of 50.37 mL/mg. Under the optimal conditions, the yield of the reduction reaction reached 77.54 %, close to the theoretical value of 76.97 %. The optimization model was suitable for the experiment data. Besides, the morphology, density, and characteristics of AgNPs on the surface of HT layers have been determined by using Ultraviolet-visible spectroscopy, Field emission scanning electron microscopy (FESEM), High-resolution transmission electron microscopy (HR-TEM), selected area diffraction, X-ray diffraction, Dynamic light scattering (DLS), Infrared (IR) spectroscopy, Fluorescence emission spectroscopy (FE), Brunauer-Emmett-Teller (BET) methods. The spherical AgNPs were synthesized successfully on the surface of HT with the average particle size of 13.0±1.1 nm. Interestingly, HT-Ag hybrid materials can inhibit strongly the growth of E. coli, S. aureus as well as two antibiotic resistance bacterial strains, P. stutzeri B27, and antibiotic resistance E. coli. Especially, the antibacterial activity quantification and durability of the HT-Ag hybrid materials were also tested. Overall, the HT-Ag hybrid materials are very promising for application in material science and biomedicine fields.

Clinical diagnosis and assessment of severity of confirmed dengue infections in Vietnamese children: is the world health organization classification system helpful?

Classification of dengue using the current World Health Organization (WHO) system is not straightforward. In a large prospective study of pediatric dengue, no clinical or basic laboratory parameters clearly differentiated between children with and without dengue, although petechiae and hepatomegaly were independently associated with the diagnosis. Among the 712 dengue-infected children there was considerable overlap in the major clinical features. Mucosal bleeding was observed with equal frequency in those with dengue fever and dengue hemorrhagic fever (DHF), and petechiae, thrombocytopenia, and the tourniquet test differentiated poorly between the two diagnostic categories. Fifty-seven (18%) of 310 with shock did not fulfill all four criteria considered necessary for a diagnosis of DHF by the WHO, but use of the WHO provisional classification scheme resulted in considerable over-inflation of the DHF figures. If two separate entities truly exist rather than a continuous spectrum of disease, it is essential that some measure of capillary leak is included in any classification system, with less emphasis on bleeding and a specific platelet count.

Candida easanensis sp. nov., Candida pattaniensis sp. nov. and Candida nakhonratchasimensis sp. nov., three new species of yeasts isolated from insect frass in Thailand.

Six strains of anamorphic yeasts isolated from insect frass collected in several regions of Thailand were assigned to the genus Candida based on the conventional taxonomic criteria used for yeast classification. These strains have Q-7 as the major ubiquinone and are suggested to have close relationships to the genus Pichia. Three strains, ST-225, ST-228 and ST-229, have identical nucleotide sequences in the D1/D2 domain of 26S rDNA and are closely related to Pichia japonica, but differ by six nucleotides (1.1% ) from this species. These three strains are considered to represent a single new species, which is described as Candida easanensis sp. nov. Two strains, ST-311 and ST-320, have identical sequences in the D1/D2 domain and resemble Pichia veronae and Pichia fabianii but differ from them by nine nucleotides (1.6%) in D1/D2 sequences. The two strains are described as Candida pattaniensis sp. nov. The remaining strain, ST-37, is related to Pichia americana and Pichia bimundalis but differs by six(1.1%) and seven (1.2%) nucleotides from these species, respectively. This strain is described as Candida nakhonratchasimensis sp. nov.