Contribution to the study on chemical constituents of Hedyotis auricularia L., (Rubiaceae)

From the whole plant of Hedyotis auricularia L., a new glycoside, 1’-deoxy-6’-O-(1-hydroxymethyl-2-hydroxy-1-methoxy)ethylglucopyranoside (1) was isolated along with 1’-O-ethyl-β-D-galactopyranoside (2), 2-formyl-5-hydroxymethylfuran (3), stigmasta-5,22-diene-3-O-β-D-glucopyranoside (4), ursolic acid (5) and oleanolic acid (6). Among them (1), (2), (3), (4)were the first time known to be present in this plant

Coderivatives at infinity of set-valued mappings

In this paper, the concept of coderivatives at infinity of set-valued mappings is introduced. Well-posedness properties at infinity of set-valued mappings as well as Mordukhovich's criterion at infinity are established. Fermat's rule at infinity in set-valued optimization is also provided. The obtained results, which give new information even in the classical cases of smooth single-valued mappings, provide complete characterizations of the properties under consideration in the setting at infinity of set-valued mappings

Some triterpenoids and steroids from Bruguiera cylindrica leaves collected from Can Gio mangrove forest

Bruguiera cylindrica (Rhizophoracea), distributed in the Southeast Asia, has been used as a traditional medicine in the treatment of diarrhea and healing of wounds. Some triterpenoids and steroids were isolated from the dried leaves of Bruguiera cylindrica, collected at Can Gio mangrove forest, Ho Chi Minh City, including lupeol (1), 3β-hydroxyoleana-9(11),12-diene (2), a mixture of stigmasterol (3a) and b-sitosterol (3b), cholesta-4-ene-3-one (4) and 3β-hydroxycholesta-5-ene-7-one (5). Their chemical structures were elucidated by spectroscopic analysis as well as comparing their data with the ones in the literature. Although these compounds were known in other plants this is the first time they are reported in this species. Keywords. Bruguiera cylindrica, triterpenoids, steroids

OVERVIEW OF ARSENIC CONTAMINATION IN GROUNDWATER AND HUMAN HEALTH RISK IN VIETNAM

Joint Research on Environmental Science and Technology for the Eart

Using metagenomics tool to evaluate the enrichment efficiency of methanogens in marine sediment in Truong Sa archipelage, Khanh Hoa province, Vietnam

Methanogens (archaea bacteria that produce methan) play an important role in the anaerobic digestion of organic waste, however, in marine environment, the low density of methanogens makes anaerobic digestion very slow. In this study, we used methagenomics tool to evaluate the enrichment efficiency of methanogens communities in marine sediments as a basis for building a anaerobic microbial formulation to treat organic waste in marine environment. The results of determination of methanogen density by MPN method have shown that methanogen has been accumulated with higher density (up to 3.2.107 MNP/ml) through 2 times of enrichment in artificial seawater with CH3COONa 10 mM substrate. In addition, metagenomics data have also shown a decrease in the number of archaea species through each enrichment, indicating that methanogenic species have gradually dominated the microbial community. This is the first study on using metagnenomics tools to evaluate the enrichment of methanogens in marine sediment samples in Truong Sa archipelago, Vietnam. Metagenomics data help provide more reliable evidence in microbial studies, especially in obligate anaerobes such as methanogens

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

Multidrug resistance plasmids underlie clonal expansions and international spread of Salmonella enterica serotype 1,4,[5],12:i:- ST34 in Southeast Asia

Salmonella enterica serotype 1,4,[5],12:i:- (Typhimurium monophasic variant) of sequence type (ST) 34 has emerged as the predominant pandemic genotype in recent decades. Despite increasing reports of resistance to antimicrobials in Southeast Asia, Salmonella ST34 population structure and evolution remained understudied in the region. Here we performed detailed genomic investigations on 454 ST34 genomes collected from Vietnam and diverse geographical sources to elucidate the pathogen’s epidemiology, evolution and antimicrobial resistance. We showed that ST34 has been introduced into Vietnam in at least nine occasions since 2000, forming five co-circulating major clones responsible for paediatric diarrhoea and bloodstream infection. Most expansion events were associated with acquisitions of large multidrug resistance plasmids of IncHI2 or IncA/C2. Particularly, the self-conjugative IncA/C2 pST34VN2 (co-transferring blaCTX-M-55, mcr-3.1, and qnrS1) underlies local expansion and intercontinental spread in two separate ST34 clones. At the global scale, Southeast Asia was identified as a potential hub for the emergence and dissemination of multidrug resistant Salmonella ST34, and mutation analysis suggests of selection in antimicrobial responses and key virulence factors

Multidrug resistance plasmids underlie clonal expansions and international spread of Salmonella enterica serotype 1,4,[5],12:i:- ST34 in Southeast Asia

Salmonella enterica serotype 1,4,[5],12:i:- (Typhimurium monophasic variant) of sequence type (ST) 34 has emerged as the predominant pandemic genotype in recent decades. Despite increasing reports of resistance to antimicrobials in Southeast Asia, Salmonella ST34 population structure and evolution remained understudied in the region. Here we performed detailed genomic investigations on 454 ST34 genomes collected from Vietnam and diverse geographical sources to elucidate the pathogen’s epidemiology, evolution and antimicrobial resistance. We showed that ST34 has been introduced into Vietnam in at least nine occasions since 2000, forming five co-circulating major clones responsible for paediatric diarrhoea and bloodstream infection. Most expansion events were associated with acquisitions of large multidrug resistance plasmids of IncHI2 or IncA/C2. Particularly, the self-conjugative IncA/C2 pST34VN2 (co-transferring bla CTX-M-55, mcr-3.1, and qnrS1) underlies local expansion and intercontinental spread in two separate ST34 clones. At the global scale, Southeast Asia was identified as a potential hub for the emergence and dissemination of multidrug resistant Salmonella ST34, and mutation analysis suggests of selection in antimicrobial responses and key virulence factors