Editorial: Topical issue "Nanomaterials for energy- and environment-related applications"

© Elsevier Ltd. Available online 26 May 2020. Symposium on Metal Oxide-and Oxyhydride-Based Nanomaterials for Energy and Environment-Related Applications of the E-MRS (2019. Varsovia)Depto. de Física de MaterialesFac. de Ciencias FísicasTRUEpu

BIODIVERSITY ASSESSMENT OF MICROORGANISMS ASSOCIATED WITH TWO MARINE SPONGES (Haliclona oculata AND Amphius huxleyi) COLLECTED AT THE LANG CO BAY OF VIETNAM

Sponges (Phylum Porifera) are ancient sedentary and filter-feeding animals which harbour very diverse and abundant associated microbial community in their tissues with density up to 40–50% of sponge tissue volume. In this study, the diversity of associated microorganisms with two marine sponges Haliclona oculata and Amphius huxleyi collected at the Lang Co bay of Vietnam was assessed by analysis of hypervariable V3 and V4 regions of the 16S rRNA gene using Illumina MiSeq system. The taxonomic diversity of sponge-associated microorganisms was classified to different taxonomic levels (kingdom, phylum, class, order, family, and genus). Based on Bayesian classification method and reference sequences derived from Greengenes database, the associated microorganisms in studied sponges were assigned to 17 phyla (H. oculata) and 13 phyla (A. huxleyi). Many microbial taxa were detected in two sponge species, however, they were distinctive by the abundance. Proteobacteria was the most dominant phylum in both sponge species, and all of 4 classes Epsilonproteobacteria, Gammaproteobacteria, Alphaproteobacteria, and Deltaproteobacteria were found in H. oculata and A. huxleyi

Enhancement of the UV emission from gold/ZnO nanorods exhibiting no green luminescence

Large reflection losses at interfaces in light-emitting semiconductor devices cause a significant reduction in their light emission and energy efficiencies. Metal nanoparticle (NP) surface coatings have been demonstrated to increase the light extraction efficiency from planar high refractive index semiconductor surfaces. This emission enhancement in Au NP-coated ZnO is widely attributed to involvement of a green (∼ 2.5 eV) deep level ZnO defect exciting localized surface plasmons in the NPs. In this work, we achieve a 6 times enhancement of the ultra-violet excitonic emission in ZnO nanorods coated with 5 nm Au NPs without the aid of ZnO defects. Cathodoluminescence (CL) and photoluminescence (PL) spectroscopy revealed that the increased UV emission is due to the formation of an additional fast excitonic relaxation pathway. Concurrent CL-PL measurements ruled out the presence of charge transfer mechanism in the emission enhancement process. While time-resolved PL confirmed the existence of a new excitonic recombination channel that is attributed to exciton relaxation via the excitation of rapid non-radiative Au interband transitions that increases the UV spontaneous emission rate. Our results establish that ZnO defect levels ∼ 2.5 eV are not required to facilitate Au NP induced enhancement of the ZnO UV emission

Phylogenetic diversity of microorganisms associated with three marine sponges from Mien Trung sea of Vietnam

Using culture - independent technique, hypervariable V4 region of 16S rDNA library sequencing by MiSEq, the baterial communities of three host sponges Rhabdastrella sp. DN, Spheciospongia sp. QT and Clathria sp. NT from Mien Trung sea were characterized. The phylogenetic analysis showed that bacterial community structures of the three investigated sponges similar to each other regarding 10 common phyla, although abundance of these phyla was different for each sponge. Phylum Thaumarchaeota was rich component for three sponges, especially in NT sponge (31.89%). In this sponge, 3 phyla Planctomycetes, Verrucomicrobia and Firmicutes were undetected in other 2 sponge samples. Phyla Cyanobacteria was observed only in DN sponge. The obtained amplicons were assigned in different taxonomic levels (class, order, family and genus) based on Silva database. At class level, Gammaproteobacteria was abundant in three sponges; and  Caldilineae, Marine-group I were dominant in DN; mealwile, in QT other dominant classes were Marine-group I and Betaproteobacteria. For NT, they were Cytophaga and Deferribacteres. In general, all three sponges harbored abundant and genetically diverse microbial associated consortia and they shared several common bacterial operational taxonomic units, although with different abundance

Experimental cultivation of Spirulina platensis using My An mineral water, Thua Thien Hue province

Spirulina platensis was experimentally cultivated by semi-continuous method at 20m2 scale pilot to effectively use the available bicarbonate and minerals of the My An mineral water, Phu Vang district, Thua Thien Hue province, and reduce production cost. Analyses of My An water quality showed that this mineral water source was suitable to cultivate Spirulina Platensis after removing H2S. The average algal yield reached to 10gDW/m2.day. The obtained algal biomass contained high nutrient compositions and was a suitable source for functional food (68.32 % protein, 7.32 % lipids containing Omega-3 and Omega-6, and low heavy metal concentration). The obtained results indicated that the My An mineral water source was indeed a suitable water source for producing Spirulina platensis biomass as a functional food

Radiative recombination of confined electrons at the MgZnO/ZnO heterojunction interface

We investigate the optical signature of the interface in a single MgZnO/ZnO heterojunction, which exhibits two orders of magnitude lower resistivity and 10 times higher electron mobility compared with the MgZnO/Al2O3 film grown under the same conditions. These impressive transport properties are attributed to increased mobility of electrons at the MgZnO/ZnO heterojunction interface. Depth-resolved cathodoluminescence and photoluminescence studies reveal a 3.2 eV H-band optical emission from the heterointerface, which exhibits excitonic properties and a localization energy of 19.6 meV. The emission is attributed to band-bending due to the polarization discontinuity at the interface, which leads to formation of a triangular quantum well and localized excitons by electrostatic coupling