Diverse polarization angle swings from a repeating fast radio burst source.

Fast radio bursts (FRBs) are millisecond-duration radio transients1,2 of unknown origin. Two possible mechanisms that could generate extremely coherent emission from FRBs invoke neutron star magnetospheres3-5 or relativistic shocks far from the central energy source6-8. Detailed polarization observations may help us to understand the emission mechanism. However, the available FRB polarization data have been perplexing, because they show a host of polarimetric properties, including either a constant polarization angle during each burst for some repeaters9,10 or variable polarization angles in some other apparently one-off events11,12. Here we report observations of 15 bursts from FRB 180301 and find various polarization angle swings in seven of them. The diversity of the polarization angle features of these bursts is consistent with a magnetospheric origin of the radio emission, and disfavours the radiation models invoking relativistic shocks.

[The prognostic analysis of hepatocellular carcinoma based on the tumor neo-vessels, macrophages and α-SMA in tumor microenvironment].

Objective: To analyze the quantitative expression and prognostic significance of tumor neo-vessels, macrophages and fibroblasts in tumor microenvironment of hepatocellular carcinoma (HCC). Methods: The clinic-pathological features and tissue samples for 101 HCC cases were collected. Immunohistochemistry was used to stain the tumor neo-vessels, macrophages and fibroblasts on tumor tissue. The distribution results and quantitative data of above key components were acquired by inverted microscopy equipped with CRi Nuance multispectral analysis system. The number of tumor neo-vessels and macrophages on HCC tissue were counted and the thickness of cancer stroma based on the expression of fibroblasts was measured. The clinic-pathological characteristics and overall survival were analyzed. Results: The median disease free survival (DFS) of 101 HCC cases was 5 month. The quantitative analysis of tumor neo-vessels, macrophages and fibroblasts showed that the expression range was 51-429 with median 218, 110-555 with median 259, 35.61-555.35 with median 246.98, respectively. To take the median as cutoff, all the cases could be classified into high and low expression group. The survival analysis demonstrated that the high density group of macrophages (P=0.022) and fibroblasts (P<0.001) has shorter DFS than low density group, with statistical significance. The high tumor neo-vessels group has shorter DFS with median 5 month than low density group with median 7 month. However, there was no statistical significance between these two group (P=0.197). Combined with above the three stromal components, all the cases could be classified into low, middle and high group. The survival analysis demonstrated that the high density group of stromal components has shorter DFS than the other two groups with median 3 month (P=0.001). Multivariate analysis by Cox regression indicated that cirrhosis, metastasis status, macrophages and fibroblasts density were the independent prognostic factors. Conclusion: The key elements in tumor microenvironment including tumor neo-vessels, macrophages and fibroblasts were heterogenic in HCC tissues and played significant roles in HCC invasion and metastasis.

Characterization of a novel biosurfactant produced by marine hydrocarbon-degrading bacterium Achromobacter sp. HZ01.

AIMS: To purify and characterize the biosurfactants produced by Achromobacter sp. HZ01. METHODS AND RESULTS: After fermentation, one biosurfactant was successfully purified from the fermentation broth of strain HZ01 by centrifugation, extraction using ethyl acetate, silica gel chromatography and reversed phase-high performance liquid chromatography. The critical micelle concentration (CMC) of the biosurfactant and the effects of temperatures, pH and salinities on its stability were determined. Fourier transform infrared spectroscopy, analysis of fatty acids and amino acids and mass spectrometry were used to characterize the biosurfactant. The maximum production yield of the crude biosurfactant reached to 6·84 g l(-1) after incubation for 96 h. Except the favourable adaptability to a wide range of temperatures, pH and salinities, the biosurfactant with a CMC value of 48 mg l(-1) could efficiently emulsify diverse hydrophobic compounds. The chemical formula of this biosurfactant was confirmed to be CH3 -(CH2 )17 -CHO-CH2 -CO-Gly-Gly-Leu-Met-Leu-Leu, in which the oxygen atom of group CHO linked to the last amino acid (Leu), a structure had never been reported before. CONCLUSIONS: The purified biosurfactant is a novel cyclic lipopeptide. SIGNIFICANCE AND IMPACT OF THE STUDY: One novel lipopeptide was purified and characterized. The novel biosurfactant exhibited good potential applications, such as bioremediation.