Curie Temperature of Diluted Magnetic Semiconductors: the Influence of the Antiferromagnetic Exchange Interaction

The coherent potential approximation and mean field approximation are used to calculate the free energy of the coupled carrier – localized spin system in III-V diluted magnetic semiconductors. Thus the magnetic transition temperature Tc can be determined and its dependence on important model parameters. We show that the strong antiferromagnetic superexchange interaction between nearest neighbour sites considerably reduces the Curie temperature

Two Band Model for Diluted Magnetic Semiconductors: Study of the Ferromagnetic Transition Temperature

The ferromagnetic transition temperature (Tc) of a two band model for diluted magnetic semiconductors (DMS) is calculated by using the coherent potential approximation (CPA). It is shown that Tc is strongly parameter dependent on density of the carriers, magnetic coupling constants, and the hopping terms. The maximal Tc of the two band model is found when both impurity bands fully overlap and this value is approximately twice larger than the highest Tc obtained in the single band model

Temperature dependent magnetization of the two band model for diluted magnetic semiconductors

The temperature dependent magnetization of a two band model for diluted magnetic semiconductors as a function of magnetic coupling constant, hopping parameters and carrier densities is calculated by using the coherent potential approximation.  It is shown that the degree of overlapping of the impurity bands  and carrier density are crucial parameters determining the magnetization behavior of the system

Reducing inequality of human opportunities in Vietnam : a challenge for social progress

The paper updates the status (2012) of education and housing infrastructure opportunities as well as examines a new indicator relating to healthcare service. Eight geographical regions are considered. Education levels of household heads, well-being and regional circumstances are the most crucial factors in determining inequality of children’s opportunities, including access to housing. Access to improved safe water and sanitation seems to depend on ethnicity and location. To sum up, children in the most vulnerable groups usually live with less educated heads of poor households, in rural area and are ethnic minorities

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AN UPDATED CHECKLIST AND COMMENTS FOR SECTION PIQUETIA (CAMELLIA, THEACEAE)

New Camellia species in section Piquetia have recently been discovered. It is necessary to enumerate the number of species and update the specific characteristics of this section. Based on the study of more than 30 pieces of literature and a large number of specimens, a total of 15 species belonging to section Piquetia, including two new species, are identified. A taxonomic key to all species is provided, and typical characteristics of the section are also discussed. Information on the distribution, ecology, and conservation status of each species, as well as notes on the differences between closely related species, is also provided.

. In vitro propagation of the new orchid Dendrobium trankimianum T. Yukawa

Dendrobium trankimianum T. Yukawa is a beautiful, endemic orchid of Vietnam, a new species with a first - published description in 2004. It is very rare and expected to be added to the IUCN Red List status - CR. In vitro studies of orchid D. trankimianum T. Yukawa were conducted in order to conserve and increase the genetic pool of this precious wild orchid species. The results showed that full-strength MS medium supplemented with 2.0 mg/L BA and 0.5 mg/L NAA (10.24 PLBs/explant; 90.11% explants formed PLBs) or full-strength MS medium supplemented with 1.5 mg/L TDZ and 0.5 mg/L NAA (14.11 PLBs/explant; 92.06% explants formed PLBs) were the most suitable for protocorm formation. For subculture, suitable growth of shoots were obtained on full-strength MS medium supplemented 1.5 mg/L BA (22.35 shoots/explant; shoots length of 1.96 cm) and full-strength MS medium supplemented with 60 g ripe banana per liter (25.11 shoots/explant; shoots length of 2.12 cm). The shoots in vitro were transferred to half-strength MS supplemented with different concentrations of IAA, IBA and NAA to investigate root formation. The best rooting occurred at 0,5 mg/L NAA (7.91 roots/shoot; root length of 4.01 cm; 98.51% root formation). The plantlets with uniform growth were planted on different substrate: Eco clean soil, Coconut fiber, Fern fiber, 50% Rice husk in combination with 50% Eco clean soil for research the most suitable substrate. After 60 days of transplantion and acclimatization, the result showed that Fern fiber was suitable substrate for plantlet growth in a nursery garden (8.0 roots/ explant; root length of 5.5 cm; survival rate of 93.29%)

UV Light Induced Thermoluminescence of Rare Earth doped Nanomaterials Y2_2O3_3:Eu3+^{3+}, Gd2_2O3_3:Eu3+^{3+} and Gd2_2O3_3:Er3+^{3+}

Thermoluminescence  properties of ultraviolet irradiated Y2O3:Eu3+, Gd2O3:Eu3+ and Gd2O3:Er3+ nanophosphors have been reported. The materials were synthesized by gel- combustion method with EDTA- Na2 as organic agent. This method allows production of very fine white powder at low temperature with very high efficiency. XRD has been studied to determine the structure of the prepared nano powders. The obtained materials exhibit sufficient sensibility to UV radiation and may be useful in UV light measurements

Expansion of KPC-producing Enterobacterales in four large hospitals in Hanoi, Vietnam

Objectives : The incidence of carbapenem resistance among nosocomial Gram-negative bacteria in Vietnam is high and increasing, including among Enterobacterales. In this study, we assessed the presence of one of the main carbapenemase genes, blaKPC, among carbapenem-resistant Enterobacterales (CRE) from four large hospitals in Hanoi, Vietnam, between 2010 and 2015, and described their key molecular characteristics. Methods : KPC-producing Enterobacterales were detected using conventional PCR and were further analysed using S1 nuclease pulsed-field gel electrophoresis (S1-PFGE), Southern blotting and whole-genome sequencing (WGS) for sequence typing and genetic characterisation. Results : blaKPC genes were detected in 122 (20.4%) of 599 CRE isolates. blaKPC-carrying plasmids were diverse in size. Klebsiella pneumoniae harbouring blaKPC genes belonged to ST15 and ST11, whereas KPC-producing Escherichia coli showed more diverse sequence types including ST3580, ST448, ST709 and ST405. Genotypic relationships supported the hypothesis of circulation of a population of ‘resident’ resistant bacteria in one hospital through the years and of transmission among these hospitals via patient transfer. WGS results revealed co-carriage of several other antimicrobial resistance genes and three different genetic contexts of blaKPC-2. Among these, the combination of ISEcp1–blaCTX-M and ISKpn27–blaKPC–ΔISKpn6 on the same plasmid is reported for the first time. Conclusion : We describe the dissemination of blaKPC-expressing Enterobacterales in four large hospitals in Hanoi, Vietnam, since 2010, which may have started earlier, along with their resistance patterns, sequence types, genotypic relationship, plasmid sizes and genetic context, thereby contributing to the overall picture of the antimicrobial resistance situation in Enterobacterales in Vietnam

Host Transcription Profile in Nasal Epithelium and Whole Blood of Hospitalized Children Under 2 Years of Age With Respiratory Syncytial Virus Infection.

BACKGROUND: Most insights into the cascade of immune events after acute respiratory syncytial virus (RSV) infection have been obtained from animal experiments or in vitro models. METHODS: In this study, we investigated host gene expression profiles in nasopharyngeal (NP) swabs and whole blood samples during natural RSV and rhinovirus (hRV) infection (acute versus early recovery phase) in 83 hospitalized patients <2 years old with lower respiratory tract infections. RESULTS: Respiratory syncytial virus infection induced strong and persistent innate immune responses including interferon signaling and pathways related to chemokine/cytokine signaling in both compartments. Interferon-α/β, NOTCH1 signaling pathways and potential biomarkers HIST1H4E, IL7R, ISG15 in NP samples, or BCL6, HIST2H2AC, CCNA1 in blood are leading pathways and hub genes that were associated with both RSV load and severity. The observed RSV-induced gene expression patterns did not differ significantly in NP swab and blood specimens. In contrast, hRV infection did not as strongly induce expression of innate immunity pathways, and significant differences were observed between NP swab and blood specimens. CONCLUSIONS: We conclude that RSV induced strong and persistent innate immune responses and that RSV severity may be related to development of T follicular helper cells and antiviral inflammatory sequelae derived from high activation of BCL6