Identification of suspended particulate matters as the hotspot of polycyclic aromatic hydrocarbon degradation-related bacteria and genes in the Pearl River Estuary using metagenomic approaches.

Bacterial degradation is unequivocally considered as an important way for the cleanup of polycyclic aromatic hydrocarbon (PAHs) in the aquatic environment. However, the diversity and distribution of PAH-degrading bacterial communities and PAH degradation-related genes (PAHDGs) in ambient environment need to be investigated. In this study, bacteria in the water of the Pearl River Estuary (PRE) were initially separated as the particle-attached bacteria (PAB) and free-living bacteria (FLB), and were further characterized using metagenomic approaches. Proteobacteria (80.1 %) was identified as the most abundant PAH-degrading phylum in the PRE water, followed by Bacteroidetes, Actinobacteria, and Firmicutes. A substantial difference in the community structure was observed between PAH-degrading PAB and FLB. Both of PAH-degrading bacteria and PAHDGs were enriched on the suspended particulate matters (SPMs), with the range of enrichment factor (EF) from 7.84 × 104 to 6.64 × 106 (PAH-degrading bacteria) and from 1.14 × 103 to 1.76 × 105 (PAHDGs). The levels of PAH-degrading bacteria 16 S rRNA genes and PAHDGs on the SPMs were both significantly correlated with those in the aqueous phase (AP) in the PRE water (p < 0.05), indicating a dynamic distribution of PAH-degrading bacteria between these two phases. The total PAH concentrations on the SPMs of the PRE water were also significantly correlated with the total PAHDG levels in the PAB (p < 0.05). Our results suggested that the SPMs could be the important compartment for the elimination of PAHs from the aquatic environment.

Low-activity 125I implantation into VX2 tumor rabbits and quantitative evaluation of the precise therapeutic effect.

There is still controversy about quantitatively evaluating the therapeutic effect of radioactive low-activity iodine-125 seeds (125I seeds). In the present study, a paired VX2 tumor model in a rabbit hind leg muscle was established, which is virus-induced anaplastic squamous cell carcinoma characterized by hypervascularity, rapid growth and easy propagation in the skeletal muscle. 125I seeds with 0.4 and 0.7 mCi activity were implanted into the left and right legs, respectively, using a radiation treatment planning system under positron emission tomography (PET)/computed tomography (CT) guidance. PET/CT scans and hematoxylin and eosin staining were observed at 72 h and 2 and 4 weeks after implantation to assess the therapeutic effect. The results showed that the average tumor length and standard uptake value (SUV) decreased over time, and both 125I seed groups achieved therapeutic effects at 4 weeks post-implantation. Quantitative evaluation of tumor inhibition rate, SUV variation and tumor marker ratio (Bcl-2/Bax) suggested that 0.7 mCi 125I seeds were more suitable than 0.4 mCi seeds in a clinical setting.

Activity Trends and Mechanisms in Peroxymonosulfate-Assisted Catalytic Production of Singlet Oxygen over Atomic Metal-N-C Catalysts.

We synthesized a series of carbon-supported atomic metal-N-C catalysts (M-SACs: M=Mn, Fe, Co, Ni, Cu) with similar structural and physicochemical properties to uncover their catalytic activity trends and mechanisms. The peroxymonosulfate (PMS) catalytic activity trends are Fe-SAC>Co-SAC>Mn-SAC>Ni-SAC>Cu-SAC, and Fe-SAC displays the best single-site kinetic value (1.65×105  min-1 mol-1 ) compared to the other metal-N-C species. First-principles calculations indicate that the most reasonable reaction pathway for 1 O2 production is PMS→OH*→O*→1 O2 ; M-SACs that exhibit moderate and near-average Gibbs free energies in each reaction step have a better catalytic activity, which is the key for the outstanding performance of Fe-SACs. This study gives the atomic-scale understanding of fundamental catalytic trends and mechanisms of PMS-assisted reactive oxygen species production via M-SACs, thus providing guidance for developing M-SACs for catalytic organic pollutant degradation.

Low-cost CoFe2O4/biomass carbon hybrid from metal-enriched sulfate reducing bacteria as an electrocatalyst for water oxidation.

The development of electrocatalysts for the Oxygen Evolution Reaction (OER) requires extensive and challenging research for the water splitting and fuel cell applications. Herein, we report a low-cost CoFe2O4/biomass carbon (CFO@BC/Zn) hybrid from Co-enriched Sulfate Reducing Bacteria (Co-SRB) as an electrocatalyst for OER. The electrocatalyst exhibits a low potential of 1.53 V at a current density 10 mA cm-2 and Tafel slope of 86 mV dec-1. This method does not require high-cost or long periods of preparation. The density-functional theory (DFT) calculations show a small barrier for oxygen conversion on Fe3+ of CFO (100) surface. The synthesis of CFO@BC/Zn may be a new approach for obtaining low-priced electrocatalysts for OER.

[Measurement and analysis of nanometer particles of silica and carbon black by diffuse reflection FTIR spectra].

By using FTIR-FTS3000 spectrometer and infrared diffuse reflection accessory, the spectra of the nanometer particles of silica, carbon black and their blends with different weight ratio were collected and characterized. It was found from the measured results that blue-shift and broadening phenomenon occurred in the nanometer particle materials in comparison with the mass ones. These phenomena could be explained by the little size effect and quantum size effect. No perfect spectrum could be collected because of the strong absorbance of the nanometer particle materials. For the blends of silica and carbon black there was a maximum absorption corresponding to the critical concentration, where the weight ratio of silica to carbon black was 100 : 20, and below this ratio the relationship between the function F(R) and the concentration obeyed Lambert-Beer's law. Above this ratio, the absorbance will not increase with increasing the proportion of the carbon black in the system.

Effect of molecular sieves on lipase-catalyzed esterification of rutin with stearic acid.

Rutin was acylated with stearic acid in the esterification reaction catalyzed by immobilized Candida antarctica lipase B (Novozym 435) in tert-amyl alcohol with and without molecular sieves. The lipophilic rutin stearate was synthesized by this method, which had a potential use in food, cosmetics, and pharmacy. The structure of rutin stearate was characterized by spectral methods of 1H NMR and 13C NMR, Fourier transform infrared, and UV-vis. The results suggested that the regioselectivity of the lipase-catalyzed esterification of rutin was specific at the C(4''')-position of the rhamnose moiety. It was found that the addition of molecular sieves increased both the reaction rate and the yield. The time effect of adding molecular sieves in the reaction system on the conversion of rutin stearate was further examined. Instead of adding molecular sieves at the beginning of the reaction, the addition of molecular sieves at 5, 18, 24, 31, and 44 h after the beginning of the reaction was also applied. The final conversion for the case to add molecular sieves at 24 h after the beginning of reaction was the highest, with the conversion yield about 46%.

[Chromaticity analysis for colorants in dye-based ink-jet ink].

For ink-jet color inks used for the well-known printers, taking Canon, EPSON, HEWLETT PACKARD and LEXMARK as samples, transmittances of the ink solutions were determined, and then the chromaticity analyses were made, in order to calculate the tristimulus values and the chromatic coordinate of each color sample. Also, the gamuts, chroma values, dominant wavelengths and complementary wavelengths were obtained by using the chromatic method for the samples. In this paper, an empirical formula was suggested for the relationship between the complementary wavelengths of the three primary colors: lambda compl, M approximately equal 10/9 (lambda compl, Y) + 10 and lambda compl, M approximately equal 10/9 (lambda compl, Y) - 20. It was found that the empirical formula is well suited for matching the complementary wavelengths of the three primary colors for ink sets of the samples studied.