Mn-doped CoSe2 nanosheets as high-efficiency catalysts for the oxygen evolution reaction.

In this work, we introduce for the first time an aqueous solution method followed by a selenization step to prepare Mn-doped CoSe2 nanosheets supported on nickel foam for the oxygen evolution reaction. These findings provide us highly efficient electrocatalysts instead of noble metal catalysts for the oxygen evolution reaction

Polymorphisms in thymidylate synthase gene and susceptibility to breast cancer in a Chinese population: a case-control analysis

BACKGROUND: Accumulative evidence suggests that low folate intake is associated with increased risk of breast cancer. Polymorphisms in genes involved in folate metabolism may influence DNA methylation, nucleotide synthesis, and thus individual susceptibility to cancer. Thymidylate synthase (TYMS) is a key enzyme that participates in folate metabolism and catalyzes the conversion of dUMP to dTMP in the process of DNA synthesis. Two potentially functional polymorphisms [a 28-bp tandem repeat in the TYMS 5'-untranslated enhanced region (TSER) and a 6-bp deletion/insertion in the TYMS 3'-untranslated region (TS 3'-UTR)] were suggested to be correlated with alteration of thymidylate synthase expression and associated with cancer risk. METHODS: To test the hypothesis that polymorphisms of the TYMS gene are associated with risk of breast cancer, we genotyped these two polymorphisms in a case-control study of 432 incident cases with invasive breast cancer and 473 cancer-free controls in a Chinese population. RESULTS: We found that the distribution of TS3'-UTR (1494del6) genotype frequencies were significantly different between the cases and controls (P = 0.026). Compared with the TS3'-UTR del6/del6 wild-type genotype, a significantly reduced risk was associated with the ins6/ins6 homozygous variant genotype (adjusted OR = 0.58, 95% CI = 0.35–0.97) but not the del6/ins6 genotype (OR = 1.09, 95% CI = 0.82–1.46). Furthermore, breast cancer risks associated with the TS3'-UTR del6/del6 genotype were more evident in older women, postmenopausal subjects, individuals with a younger age at first-live birth and individuals with an older age at menarche. However, there was no evidence for an association between the TSER polymorphism and breast cancer risks. CONCLUSION: These findings suggest that the TS3'-UTR del6 polymorphism may play a role in the etiology of breast cancer. Further larger population-based studies as well as functional evaluation of the variants are warranted to confirm our findings

Label-free hairpin-like aptamer and EIS-based practical, biostable sensor for acetamiprid detection.

Acetamiprid (ACE) is a kind of broad-spectrum pesticide that has potential health risk to human beings. Aptamers (Ap-DNA (1)) have a great potential as analytical tools for pesticide detection. In this work, a label-free electrochemical sensing assay for ACE determination is presented by electrochemical impedance spectroscopy (EIS). And the specific binding model between ACE and Ap-DNA (1) was further investigated for the first time. Circular dichroism (CD) spectroscopy and EIS demonstrated that the single strand AP-DNA (1) first formed a loosely secondary structure in Tris-HClO4 (20 mM, pH = 7.4), and then transformed into a more stable hairpin-like structure when incubated in binding buffer (B-buffer). The formed stem-loop bulge provides the specific capturing sites for ACE, forming ACE/AP-DNA (1) complex, and induced the RCT (charge transfer resistance) increase between the solution-based redox probe [Fe(CN)6]3-/4- and the electrode surface. The change of ΔRCT (charge transfer resistance change, ΔRCT = RCT(after)-RCT(before)) is positively related to the ACE level. As a result, the AP-DNA (1) biosensor showed a high sensitivity with the ACE concentration range spanning from 5 nM to 200 mM and a detection limit of 1 nM. The impedimetric AP-DNA (1) sensor also showed good selectivity to ACE over other selected pesticides and exhbited excellent performance in environmental water and orange juice samples analysis, with spiked recoveries in the range of 85.8% to 93.4% in lake water and 83.7% to 89.4% in orange juice. With good performance characteristics of practicality, sensitivity and selectivity, the AP-DNA (1) sensor holds a promising application for the on-site ACE detection

Paleoceanographic records in the Chukchi Basin, western Arctic Ocean during the late Quaternary

National Basic Research Program of China [G2007CB815903]; National Natural Science Foundation of China [41030859]; Chinese IPY Program; China Geological Survey [H[2011]01-14-04]The late Quaternary paleoceanographic changes in the western Arctic Ocean are revealed by quantitative studies of foraminiferal abundance, ice-rafted detritus (IR)) and its mineralogical and petrological compositions, planktonic Neogloboquadrina pachyderma (sin.) (Nps)-delta O-18 and -delta C-13, biogenic and non-biogenic components in Core M03 token from the Chukchi Basin during the Second Chinese National Arctic Expedition cruise. Seven IRD events appeared at MIS 7, 5, 3 and I. These IRD were carried in massive icebergs, which were exported to the Beaufort Sea through the M'Clure Strait Ice Stream, Canadian Arctic Archipelago, and then transported into the Chukchi Basin by the Beaufort Gyre. Low IRD deposition occurred during the glacial times when more extended ice cover and weakened Beaufort Gyre, while the open water condition and the intensified Beaufort Gyre during interglacial periods favored the I RD deposition. Therefore, the IRD events not only indicate the provenance of coarser detritus and ice export events, but also reflect the evolutionary histories of the Beaufort Gyre and North American ice sheet. Seven light Nps-delta O-18 and -delta C-13 excursions could respond to enhanced rates of sea ice formation resulting in the production and sinking of isotopically light brines, but was irrelevant to the warm Atlantic water and freshwater inputs. Whereas, the heavy Nps-delta O-18 and -delta C-13 values separately reflect the lessened Arctic freshwater and Pacific water, and well-ventilated surface water from the continental shelf and halocline water. Variations of CaCO3 content and planktonic foraminiferal abundance during the interglacial mid glacial periods can demonstrate the incremental or diminishing input of the Atlantic water, while the total organic carbon (TOG) and opal contents increased and decreased during the glacial and interglacial periods, respectively, which could be related to the TOC degradation, opal dissolution and redox conditions of interface between the bottom water and sediments

Deciphering Color Reflectance Data of a 520-kyr Sediment Core From the Southern Ocean : Method Application and Paleoenvironmental Implications

Sediment color reflectance contains important information on paleoenvironmental changes. Such data are routinely measured on sediment cores from the Southern Ocean. Their usefulness, however, is undervalued. Here for the first time, color reflectance of an ~520-kyr sediment core retrieved off Prydz Bay (East Antarctica) was intensively investigated to correlate sediment color changes to changes in sediment compositions. Total carbon, total organic carbon, X-ray fluorescence-derived Fe/Ti and Br/Ti ratios, water content and mineral composition of sediment from this core, and color reflectance of another two sediment cores retrieved nearby were analyzed in this study. The raw reflectance data were transformed into their first-order derivatives and subjected to factor analysis algorithms. A four-factor model was selected to unmix the data set, explaining >80% of the total data variance. Its robustness is supported by similar factor analysis results from the other two cores. The four factors represent (from Factors 1–4) pulses of sedimentary Mn enrichment and Fe3+/Fe2+ changes in clay minerals, relative content changes of colorless components, hematite and goethite, and water, respectively. Scores of Factor 1 show high spikes at glacial terminations, recording enhanced deglacial ventilation in the abyssal Southern Ocean. Scores of Factor 2 mainly reflect biogenic components and chlorite but are further complicated by refractory terrigenous organic carbon and Mn-oxides/-hydroxides. Higher Scores of Factor 3 occur mainly at peak interglacial intervals, associated with enhanced transport of sediment of Antarctic origin by oceanic currents. Water content (Factor 4) in the core sediment was significantly influenced by opal content and sediment grain size compositions

Deciphering Color Reflectance Data of a 520-kyr Sediment Core From the Southern Ocean : Method Application and Paleoenvironmental Implications

Sediment color reflectance contains important information on paleoenvironmental changes. Such data are routinely measured on sediment cores from the Southern Ocean. Their usefulness, however, is undervalued. Here for the first time, color reflectance of an ~520-kyr sediment core retrieved off Prydz Bay (East Antarctica) was intensively investigated to correlate sediment color changes to changes in sediment compositions. Total carbon, total organic carbon, X-ray fluorescence-derived Fe/Ti and Br/Ti ratios, water content and mineral composition of sediment from this core, and color reflectance of another two sediment cores retrieved nearby were analyzed in this study. The raw reflectance data were transformed into their first-order derivatives and subjected to factor analysis algorithms. A four-factor model was selected to unmix the data set, explaining >80% of the total data variance. Its robustness is supported by similar factor analysis results from the other two cores. The four factors represent (from Factors 1–4) pulses of sedimentary Mn enrichment and Fe3+/Fe2+ changes in clay minerals, relative content changes of colorless components, hematite and goethite, and water, respectively. Scores of Factor 1 show high spikes at glacial terminations, recording enhanced deglacial ventilation in the abyssal Southern Ocean. Scores of Factor 2 mainly reflect biogenic components and chlorite but are further complicated by refractory terrigenous organic carbon and Mn-oxides/-hydroxides. Higher Scores of Factor 3 occur mainly at peak interglacial intervals, associated with enhanced transport of sediment of Antarctic origin by oceanic currents. Water content (Factor 4) in the core sediment was significantly influenced by opal content and sediment grain size compositions