Detection of Cd2+ in Aqueous Solution by the Fluorescent Probe of CdSe/CdS QDs Based on OFF-ON Mode.

The detection of heavy metals in aqueous solutions has always attracted much attention from all over the world. A fluorescent probe of CdSe/CdS core-shell quantum dots (QDs) was designed to detect trace Cd2+ in aqueous solutions using the OFF-ON mode rapidly and efficiently, likely based on adsorption and desorption reactions between ethylenediaminetetraacetic acid disodium salt (EDTA) and CdSe/CdS QDs. In the OFF mode, the optical shielding function of EDTA results in fluorescence quenching owing to the strong adsorption ability of EDTA with Cd2+ on the sites of CdSe/CdS QDs surface. In the ON mode, the introduction of Cd2+ promotes the desorption of EDTA from the EDTA-CdSe/CdS QDs and restores the fluorescence intensity. There were two linear response ranges which were 0.1-20 µmol/L and 20-90 µmol/L for the EDTA-CdSe/CdS system to detect Cd2+. The detection limit was 6 nmol/L, and the standard deviation was below 4% for the detection of Cd2+ concentration in tap water.

Solid alcohol based on waste cooking oil: Synthesis, properties, micromorphology and simultaneous synthesis of biodiesel.

Solid alcohols based on waste cooking oil (WCO) and other edible oils (butter or soybean oil) were synthesized by a simple one-step method. The effects of sodium hydroxide (NaOH) dosage and type of oil on the combustion performances were explored. IR spectroscopy and micro-morphologies of the oil based solid alcohols were also studied. Results showed that, for oil based solid alcohol, use of an appropriate excess of NaOH and an oil with lower iodine value produced the solid alcohol with better combustion performance. Centrifugation produced the bottom waste cooking oil (B-WCO) with lower iodine value and the supernatant waste cooking oil (S-WCO) with higher iodine value. The B-WCO afforded solid alcohol with longer combustion time, higher melting temperature and relatively low combustion residue rate, whereas the S-WCO could be used for synthesizing biodiesel.

Genetic polymorphism of mitochondrial DNA in Dong, Gelao, Tujia, and Yi ethnic populations from Guizhou, China.

To reveal the genetic structures and relationships of the four ethnic populations from the maternal inheritance and explore the origins and migrations of nationalities, the genetic polymorphism of mtDNA in Dong, Gelao, Tujia, and Yi populations from Guizhou was studied by direct sequencing of hypervariable segment I(HVS I) and PCR-RFLP of coding region. Thirty-seven (sub-) haplogroups were identified in the classification tree of mtDNA haplogroups. Haplogroup distributions and principal component (PC) analysis showed that the Dong has high frequencies of south-prevalent haplogroups, which indicates that it is a typically southern population. The Yi harbors high frequencies of the south-prevalent and northern-prevalent haplogroups, which demonstrates that it inherits the maternal characteristics from both southern and northern populations. The Yi and Gelao cluster together, the reason for which might be that their ancestries frequently underwent gene exchanges and mixtures.

[The genetic relation of four ethnic populations in China's Guizhou is revealed by sequence variations of mtDNA D-loop].

OBJECTIVE: Through maternal inheritance, to explore the genetic structures and relationships of Dong, Gelao, Tujia and Yi ethnic population in Guizhou of China. METHODS: The mtDNA D-loop hypervariable segment I (HVS I ) in 108 samples of four ethnic populations were sequenced. Then, the nucleotide diversity was estimated and a phylogenetic tree was constructed by Neighbor-Joining method. RESULTS: In the detected 497 bp fragments, 86 polymorphic sites were found, and 82 different haplotypes were identified. The phylogenetic tree of four ethnic populations showed: Yi, Tujia and Gelao clustered more closely than Dong did. CONCLUSION: Yi and Tujia population are very closely related, the reason may be that they either originate from a common ancestry or frequently undergo the gene exchanges and admixtures. The genetic relationship between Tujia and Gelao population is nearer, perhaps because they have settled in the adjacent regions. Dong and Yi population show the farthest genetic relationship, this is probably due to their different historical origins and geographic segregation.