Application of a Diatom Transfer Function to Quantitative Paleoclimatic Reconstruction — A Case Study of Yunlong Lake, Southwest China

Although diatom records from lake sediments have been used for quantitative paleoclimatic reconstruction, their validity and sensitivity have rarely been tested rigorously. At Yunlong Lake, an alpine lake in Southwest China, we studied the seasonal succession of diatom assemblages to produce a mean surface water temperature (MSWT) transfer function. In addition, based on the spatial distribution of surface diatom assemblages with water depth, we produced a diatom-water depth (WD) transfer function. Combined with the analysis of diatom assemblages in a sediment core (YL2013-A), changes in surface water temperature and water level over the last ∼100 years were quantitatively reconstructed using the diatom-based transfer functions. Comparison with records of regional meteorology and reservoir water capacity revealed that the diatom-based lake water level reconstruction is a sensitive indicator of short-term fluctuations in precipitation, and it also reflects a long-term stepwise rise in water level caused by the impounding and large-scale extension of the reservoir. In addition, the diatom-inferred MSWT is consistent with the changes in air temperature prior to large-scale human disturbance of the site. However, after the extension of the reservoir, although the regional air temperature continued to increase, the water temperature decreased substantially. This suggests that the large increase in lake water volume in the short term led to a decrease in the average water temperature, which in turn led to the occurrence of a diatom bloom in the cold season. The results demonstrate that diatom transfer functions based on modern observations of the same lake has a high environmental sensitivity and can be used for the quantitative reconstruction of regional climate change. Overall, our findings provide a foundation for the use of lake diatom records for quantitative paleoclimatic reconstruction on various timescales

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Bromo-catalyzed photo esterification of benzylsilanes with alcohols under aerobic conditions

A photoinduced esterification reaction has been developed. In this reaction, benzylsilane shows very nice reactivity and selectivity, affording the corresponding esters as the only products. Under photo irradiation, the highly active bromo radical can be generated from the pre-catalyst CBr4, which would promote the initial CSi bond cleavage of benzylsilane via single electron transfer and the final transformation of acetal into ester via proton transfer. The existence of oxygen can not only oxidize the in situ generated benzyl radical into aldehyde intermediate, but also assist to regenerate bromo radical from bromine anion

Synthesis of Fe3O4/polypyrrole/polyaniline nanocomposites by in-situ method and their electromagnetic absorbing properties

Fe3O4/PPy/PANI (Fe3O4/polypyrrole/polyaniline) nanocomposites with excellent microwave absorbing properties have been successfully synthesized and characterized systematically. In detail, Fe3O4 nanoparticles were prepared via an environmental friendly, modified co-precipitation method. Afterward, two conductive polymers, PPy and PANI, were deposited onto the surface of Fe3O4 nanoparticles by in-situ polymerization of pyrrole and aniline. PPy and PANI was “glued” by the strong affinity between the carbonyl groups of PPy and the conjugated chains of PANI. The obtained Fe3O4/PPy/PANI nanocomposites have been found to possess excellent microwave absorbing property with the absorption bandwidth of 10.7 GHz (6.7–17.4 GHz) and maximum reflection loss at 10.1 GHz (−40.2 dB). It proves that the combination of ultra-small Fe3O4 nanoparticles with two different conductive polymers have a great potential in the application of microwave absorbing materials

Facile synthesis of Fe3O4/reduced graphene oxide/polyvinyl pyrrolidone ternary composites and their enhanced microwave absorbing properties

In this paper, ternary nanocomposites of Fe3O4/reduced graphene oxide/polyvinyl pyrrolidone (Fe3O4/rGO/PVP) as a novel type of electromagnetic microwave absorbing materials were synthesized by a three-step chemical approach. First, Fe3O4 nanospheres were made by solvent thermal method. Successively, the Fe3O4 particles were assembled with rGO after having activated by para-aminobenzoic acid. PVP grafting and reduction of GO happened simultaneously in the third step. It is found that the electromagnetic absorption (EA) performance of synthesized ternary composites with suitable PVP amount had been significantly enhanced comparing to Fe3O4 and Fe3O4/rGO. Merely 15 wt% low loading in paraffin and thin as 2.8 mm can reach effective EA bandwidth (below −10 Db) of 11.2 GHz, and the highest reflection loss reached −67 dB at 10.7 GHz. It was demonstrated that these composites show an effective route to novel microwave absorbing material design. Keywords: Nanocomposite synthesis, Wideband microwave absorbing, Reduced graphene oxide, Polyvinyl pyrrolidon

Excellent Microwave Absorption Properties Derived from the Synthesis of Hollow Fe₃o₄@Reduced Graphite Oxide (RGO) Nanocomposites

Magnetic nanoparticles, such as Fe3O4 and Co3O4, play a vital role in the research on advanced microwave absorbing materials, even if problems such as high density and narrow band impedance matching are still unsolved. Herein, the study of lightweight hollow Fe3O4@reduced graphite oxide (RGO) nanocomposites synthesized via the solvothermal method is presented. The microstructure and crystal morphology of the materials were characterized by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses. Single crystalline hollow Fe3O4 spheres were grown onto RGO flakes, leading to the formation of heterojunction, which further influenced the microwave absorption properties. The latter were evaluated by standard microwave characterization in the frequency range of 2⁻18 GHz. It was found that, for a specific [email protected] g RGO composite, the minimum reflection loss can reach −41.89 dB at 6.7 GHz, while the reflection loss was less than −10 dB from 3.4 GHz to 13.6 GHz for a nanocomposite sample thickness in the range of 1⁻4 mm. The combination of these two materials thus proved to give remarkable microwave absorption properties, owing to enhanced magnetic losses and favorable impedance matching conditions

Evaluating the Roles of sCD14 and sCD14-ST in Diagnosing COPD and Predicting an Acute Exacerbation of COPD

Abstract Aim To evaluate the roles of plasma soluble cluster of differentiation 14 (sCD14) and sCD14 subtype (sCD14-ST) in the diagnosis of chronic obstructive pulmonary disease (COPD) and in the prediction of an acute exacerbation of COPD (AECOPD). Methods We quantified the levels of white blood cell count (WBC), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), interleukin (IL)-6, IL-8, sCD14, and sCD14-ST in patients with COPD and healthy controls. The relationships between sCD14 or sCD14-ST and inflammatory markers were analyzed in each group. We used receiver operating characteristics (ROC) curves to evaluate the potential roles of sCD14 and sCD14-ST in the diagnosis of COPD and in predicting AECOPD. Results A total of 62 subjects were recruited, including 15 controls and 47 COPD patients, with the latter including 32 stable COPD and 15 AECOPD. WBC, IL-8, sCD14, and sCD14-ST were significantly higher in COPD than in the controls (all P < 0.05). WBC, CRP, ESR, IL-6, IL-8, sCD14, and sCD14-ST were higher in AECOPD than in the controls (all P < 0.05). In the COPD group, sCD14 levels were positively correlated with WBC, IL-8, and sCD14-ST (P < 0.05), and sCD14-ST levels were positively correlated with WBC and IL-8 (P < 0.05). In the AECOPD group, sCD14 was positively correlated with WBC, CRP, IL-8, and sCD14-ST (P < 0.05); sCD14-ST was positively correlated with WBC, IL-6, and IL-8 (P < 0.05). Discrimination between COPD and controls was tested by calculating areas under the ROC curve (AUCs) for sCD14 and sCD14-ST showing scores of 0.765 (95% CI 0.648–0.883) and 0.735 (95% CI 0.537–0.933) respectively. Similarly, discrimination between AECOPD and controls using sCD14 and sCD14-ST showed scores of 0.862 (95% CI 0.714–1.000) and 0.773 (95% CI 0.587–0.960), respectively. Conclusion Our study suggests that the inflammatory markers sCD14 and sCD14-ST might play an important diagnostic role in COPD and help predict AECOPD