Geochemical characteristics of biogenic barium in sediments of the Antarctica Ross Sea and their indication for paleoproductivity

241-248In this paper, the biogenic Ba of Column R11 in the Antarctic Ross Sea and its implications to the paleo oceanographic productivity since the late of Late Quaternary were discussed, combined with the organic carbon, opal and biogenic calcium carbonate. The biogenic Ba contents ranged from 51.8 to 508.4 μg/g overall, exhibiting a gradually rising trend from the bottom to the top. It highly correlated both with TOC and opal, revealing that on one hand biogenic Ba can be used to study the change of productivity in the Ross Sea; and on the other hand, the marine productivity gradually increased since the late Pleistocene. The new productivity based on Francois model varied from 0.40 to 233.90 gC/(m2•a). The high values were mainly concentrated at the depth from 32 to 48 cm, but the new productivity values of the bottom were lower. It was inferred that the change in marine productivity in the Ross Sea was possibly affected by the ice cover since the late Pleistocene

Genome Size Diversity in Lilium (Liliaceae) Is Correlated with Karyotype and Environmental Traits

Genome size (GS) diversity is of fundamental biological importance. The occurrence of giant genomes in angiosperms is restricted to just a few lineages in the analyzed genome size of plant species so far. It is still an open question whether GS diversity is shaped by neutral or natural selection. The genus Lilium, with giant genomes, is phylogenetically and horticulturally important and is distributed throughout the northern hemisphere. GS diversity in Lilium and the underlying evolutionary mechanisms are poorly understood. We performed a comprehensive study involving phylogenetically independent analysis on 71 species to explore the diversity and evolution of GS and its correlation with karyological and environmental traits within Lilium (including Nomocharis). The strong phylogenetic signal detected for GS in the genus provides evidence consistent with that the repetitive DNA may be the primary contributors to the GS diversity, while the significant positive relationships detected between GS and the haploid chromosome length (HCL) provide insights into patterns of genome evolution. The relationships between GS and karyotypes indicate that ancestral karyotypes of Lilium are likely to have exhibited small genomes, low diversity in centromeric index (CVCI) values and relatively high relative variation in chromosome length (CVCL) values. Significant relationships identified between GS and annual temperature and between GS and annual precipitation suggest that adaptation to habitat strongly influences GS diversity. We conclude that GS in Lilium is shaped by both neutral (genetic drift) and adaptive evolution. These findings will have important consequences for understanding the evolution of giant plant genomes, and exploring the role of repetitive DNA fraction and chromosome changes in a plant group with large genomes and conservation of chromosome number

The effects of different extraction methods on the aroma fingerprint, recombination and visualization of clam soup

Clam is a kind of nutritious, delicious and economical aquatic food around the world and is famous for its unique aroma. Instrumental analysis, sensory analysis, and comprehensive statistical analysis were performed to explain the relationship between aroma and odorants in clam soup. Six extraction methods combined with GC-MS and sniffing were utilized to obtain the aroma fingerprints of clam soup and to analyze the correlation with aroma perception. Solvent extraction methods were more effective than headspace extraction methods for the volatiles of clam soup. SAFE was the best method to obtain the most comprehensive information of volatiles of clam soup. The sequence of a combination of different extraction methods and SAFE would also affect the results of volatiles extracted from clam soup. Volatiles extracted via SDE, P&T, and SPME would add further information to the result of SAFE. A total of 119 volatile compounds were identified from clam soup by summarising the results of different extraction methods. The significant effect of 14 key odorants in clam soup on aroma perception was verified by aroma recombination and odorant omission tests. A neural network diagram of the aroma profile was designed to visualize the information of odor perception. Furthermore, the results would be beneficial for aroma research studies of aquatic food and the processing of clam products

Atomically-precise lanthanide-iron-oxo clusters featuring the ε-Keggin ion.

Atomically precise molecular metal-oxo clusters provide ideal models to understand metal oxide surfaces, self-assembly, and form-function relationships. Devising strategies for synthesis and isolation of these molecular forms remains a challenge. Here, we report the synthesis of four Ln-Fe oxo clusters that feature the ε -{Fe 13 } Keggin cluster in its core. The {Fe 13 } metal-oxo cluster motif is the building block of two important iron oxyhydroxyide phases in nature and technology, ferrihydrite (as the δ -isomer) and magnetite (the ε -isomer). The reported ε -{Fe 13 } Keggin isomer as an isolated molecule provides opportunity to study the formation of ferrihydrite and magnetite from this building unit. The next metal layer surrounding the ε -{Fe 13 } core within these clusters exhibit a similar arrangement as the magnetite lattice, and Fe and Ln can occupy the same positions. This provides opportunity to construct a family of compounds and optimize magnetic exchange in these molecules via composition tuning. Small angle X-ray scattering (SAXS) and high-resolution electrospray ionization mass spectrometry (HRESI-MS) show these clusters are stable upon dissolution in both water and organic solvents, as a first step to perform further chemistry towards building magnetic arrays or invetigating ferrihydrite and magnetite assembly from pre-nucleation clusters

Synthesis and applications of MOF - derived porous nanostructures

Metal organic frameworks (MOFs) represent a class of porous material which is formed by strong bonds between metal ions and organic linkers. By careful selection of constituents, MOFs can exhibit very high surface area, large pore volume, and excellent chemical stability. Research on synthesis, structures and properties of various MOFs has shown that they are promising materials for many applications, such as energy storage, gas storage, heterogeneous catalysis and sensing. Apart from direct use, MOFs have also been used as support substrates for nanomaterials or as sacrificial templates/precursors for preparation of various functional nanostructures. In this review, we aim to present the most recent development of MOFs as precursors for the preparation of various nanostructures and their potential applications in energy-related devices and processes. Specifically, this present survey intends to push the boundaries and covers the literatures from the year 2013 to early 2017, on supercapacitors, lithium-ion batteries, electrocatalysts, photocatalyst, gas sensing, water treatment, solar cells, and carbon dioxide capture. Finally, an outlook in terms of future challenges and potential prospects towards industrial applications are also discussed

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Effect of prestrain on microstructures and properties of Si-Al-Mn TRIP steel sheet with niobium

Paint baking treatment was carried out in a silicon oil bath at 170 &deg;C for 20 min for Si-Al-Mn TRIP Steel sheet with different prestrains, and effect of prestrain on microstructures and properties was studied before and after baking. The results show that with the increasing of prestrain amount during prestraining and baking, the volume fraction of retained austenite decreases, and the volume fraction of martensite and bainite increases as well as yield strength increases; as prestrain ranges from 0 to 4%, the baking-hardening (BH) value increases; while the prestrain ranges from 4% to 16%, the BH value decreases; when the prestrain amount is 4%, the highest BH value is about 70 MPa for Si-Al-Mn TRIP steel sheet with niobium, which displays excellent baking-hardening behavior.<br /

Effect of baking process on microstructures and mechanical properties of low silicon TRIP steel sheet with niobium

After 2% predeformation, the baking treatment with different schedule was carried out for low silicon TRIP steel sheet with niobium. The effects of baking temperature and time on microstructures and mechanical properties were investigated. The results showed that with increasing the baking temperature and time, the volume fraction of retained austenite decreases, and the volume fraction of tempered martensite increases; as baking temperature ranges from 80&deg;C to 170&deg;C, the bake-hardening (BH) value increases obviously, while from 170&deg;C to 230&deg;C, the variation of BH value is very slight; as baking time ranges from 2 min to 20 min, the BH value increases significantly, while the BH value decreases when baking time exceeds 20 min. So that when the baking temperature is 170&deg;C and the baking time is 20 min, the low silicon TRIP steel sheet exhibits good bake-hardening behavior, and the highest BH value is above 70 MPa.<br /