Biocatalysis of heterogenously-expressed d-lactonohydrolases and its efficient preparation of desirable d-pantoic acid.

d-Pantoic acid (D-PA) is an essential intermediate for the production of d-pantolactone. Here, three d-lactonohydrolases (D-Lacs), namely, Fm-Lac from Fusarium moniliforme SW-902, Fp-Lac from Fusarium proliferatum Nirenberg ECU2002, and Fo-Lac from Fusarium oxysporum AKU3702 were heterogeneously expressed in Pichia pastoris. The constructed recombinant strains produced D-Lacs of 1263 U/mL, 1025 U/mL, and 948 U/mL in a 3-L fermenter, respectively. Simultaneously, these three D-Lacs were used to resolve racemic pantolactone (DL-PL), the hydrolysis rate by Fo-Lac over 40% and the enantiomeric excesses was 99% after 4 h reaction, which outperformed Fm-Lac and Fp-Lac. Under the 800 mL scale reaction, the hydrolysis rate of DL-PL reached 39.2% with a D-PA concentration of 144.6 g/L and space-time yield of 36.2 g/L/h correspondingly. This is the highest catalytic efficiency reported so far, which shows that D-Lac heterologously expressed by P. pastoris has excellent industrial application prospects.

Changes in turbidity and human activities along Haihe River Basin during lockdown of COVID-19 using satellite data.

During the outbreak of the COVID-19, China implemented an urban lockdown in the first period. These measures not only effectively curbed the spread of the virus but also brought a positive impact on the ecological environment. The water quality of urban inland river has a significant impact on urban ecology and public health. This study uses Sentinel-2 visible and near-infrared band reflectance and the Normalized Difference Turbidity Index (NDTI) to analyze the water quality of the Haihe River Basin during the control period of COVID-19. It is found that during the lockdown period, the river water quality was significantly improved compared to the same period in 2019. The average NDTI of the Haihe River Basin in March decreased by 0.27, a decrease of 219.06%; in April, it increased by 0.07, that is 38.38%. Further exploration using VIIRS lights found that the brightness of the lights in the main urban area was significantly lower in February, the beginning of the lockdown. However, as the city was unblocked, the lights rose sharply in March and then recovered to normal. There is obvious asynchrony in changes between river turbidity and light. The results can help understand the impact of human activities on the natural environment.

Using Bus Ticketing Big Data to Investigate the Behaviors of the Population Flow of Chinese Suburban Residents in the Post-COVID-19 Phase.

Large-scale population movements can turn local diseases into widespread epidemics. Grasping the characteristic of the population flow in the context of the COVID-19 is of great significance for providing information to epidemiology and formulating scientific and reasonable prevention and control policies. Especially in the post-COVID-19 phase, it is essential to maintain the achievement of the fight against the epidemic. Previous research focuses on flight and railway passenger travel behavior and patterns, but China also has numerous suburban residents with a not-high economic level; investigating their travel behaviors is significant for national stability. However, estimating the impacts of the COVID-19 for suburban residents' travel behaviors remains challenging because of lacking apposite data. Here we submit bus ticketing data including approximately 26,000,000 records from April 2020-August 2020 for 2705 stations. Our results indicate that Suburban residents in Chinese Southern regions are more likely to travel by bus, and travel frequency is higher. Associated with the economic level, we find that residents in the economically developed region more likely to travel or carry out various social activities. Considering from the perspective of the traveling crowd, we find that men and young people are easier to travel by bus; however, they are exactly the main workforce. The indication of our findings is that suburban residents' travel behavior is affected profoundly by economy and consistent with the inherent behavior patterns before the COVID-19 outbreak. We use typical regions as verification and it is indeed the case.

Return Period Evaluation of the Largest Possible Earthquake Magnitudes in Mainland China Based on Extreme Value Theory.

The largest possible earthquake magnitude based on geographical characteristics for a selected return period is required in earthquake engineering, disaster management, and insurance. Ground-based observations combined with statistical analyses may offer new insights into earthquake prediction. In this study, to investigate the seismic characteristics of different geographical regions in detail, clustering was used to provide earthquake zoning for Mainland China based on the geographical features of earthquake events. In combination with geospatial methods, statistical extreme value models and the right-truncated Gutenberg-Richter model were used to analyze the earthquake magnitudes of Mainland China under both clustering and non-clustering. The results demonstrate that the right-truncated peaks-over-threshold model is the relatively optimal statistical model compared with classical extreme value theory models, the estimated return level of which is very close to that of the geographical-based right-truncated Gutenberg-Richter model. Such statistical models can provide a quantitative analysis of the probability of future earthquake risks in China, and geographical information can be integrated to locate the earthquake risk accurately.

Crepidtumines A and B, Two Novel Indolizidine Alkaloids from Dendrobium crepidatum.

Two new indolizidine alkaloids crepidatumines A (1) and B (2) together with the stereoisomer of dendrocrepidine B (3) and known analog dendrocrepine (4) were isolated from D. crepidatum. Their structures were determined by HR-ESI-MS, NMR, and Electronic Circular Dichroism (ECD) experiments together with comparison of analogues. Compound (1) possess a (5/6/6/5) tetra-hetero-cyclic ring, whereas compound (2) contains a tricyclic system with an unusual bridged ring, which are the first report in Nature. The biological evaluation revealed that dendrocrepine (4) displayed a potent hypoglycemic effect in vitro.

Acetylation and deacetylation for sucralose preparation by a newly isolated Bacillus amyloliquefaciens WZS01.

Sucralose is a non-nutritive artificial sweetener used in a broad range of foods and beverages. In the present study, Bacillus amyloliquefaciens WZS01 was isolated, identified, and used as a catalyst both in regioselective acylation and deacetylation for sucralose preparation. Bacterial cells were immobilized on polyurethane foam and utilized to synthesize sucrose-6-acetate regioselectively. The yield of sucrose-6-acetate was >95% with 60 mM sucrose after 22 h of reaction. Free cells could hydrolyze 75 mM sucralose-6-acetate to produce sucralose with >99% yield after 24 h of reaction. B. amyloliquefaciens WZS01 could be considered a potential biocatalyst for sucralose preparation.

[Super-low-frequency spectrum analysis for buried faults in coalfield].

Based on the super-low-frequency (SLF) electromagnetic detection technology, the advanced detection for the buried fault in the coalfield is still at the exploratory stage, while the technology has a strong practical significance for production and design of the coal mine. Firstly, in this paper, the SLF electromagnetic detection signals were collected in study area. Spectrum analysis of SLF signal by wavelet transform can remove high-frequency noise. Secondly, the profile of the measuring line across the fault was analyzed and interpreted geologically. Accordingly SLF spectrum characteristics of the buried fault could be researched. Finally, combined with the geological and seismic data, the characteristics and distribution of fault structures can be verified in the mining area. The results show that: the buried fault could be detected quickly and effectively by SLF electromagnetic detection Hence, SLF electromagnetic detection technology is an effective method for buried fault detection.

[Variation of monosacchride composition of polysacchrides in Dendrobium officinale by pre-column derivatization HPLC method].

The monosacchride composition of polysacchrides in Dendrobium officinal of different germplasms, physiological ages and closely related species were determined by pre-column derivatization HPLC. The results showed that the absolute and relative volumes of all monosacchrides were significantly different between D. officinale and its closely related species, different germplasms and physiological ages of D. officinale. Absolute peak areas of mannose ranged from 0.854 x 10(7) to 10.340 x 10(7) in closely related species of D. officinale, ranged from 1.467 x 10(7) to 8.475 x 10(7) in different germplasms of D. officinale and were 4.411 x 10(7) (2.577 x 10(7)-6.516 x 10(7)), 5.528 x 10(7) (3.179 x 10(7)-8.475 x 10(7)) and 3.601 x 10(7) (1.467 x 10(7)-5.888 x 10(7)), respectively, in one to three physiological ages of D. officinale. The ratio of mannose to glucose peak areas (relative peak area) ranged from 0.976 to 16.599 in closely related species of D. officinale and from 2.679 to 7.831 in different germplasms of D. officinale. Only the relative peak areas of D. pendulum and D. primulinum were in the range of different germplasms of D. officinale in all tested samples. The results revealed the variation of monosacchride composition of polysacchrides in D. officinale. Monosacchride composition of D. officinale could be altered by breeding new varieties and controlling harvesting season. Most adulterants of D. officinale could be ruled out according to the relative peak areas of D. officinale, providing a basis for quality control and resources training of D. officinale.

Production of vanillin from waste residue of rice bran oil by Aspergillus niger and Pycnoporus cinnabarinus.

A new technology of transforming ferulic acid, which was from waste residue of rice bran oil, into vanillin was developed by a combination of fungal strains Aspergillus niger CGMCC0774 and Pycnoporus cinnabarinus CGMCC1115. Various concentrations of ferulic acid were compared, and the highest yield reached 2.2 g l(-1) of vanillic acid by A. niger CGMCC0774 in a 25 l fermenter when concentration of ferulic acid was 4 g l(-1). The filtrate of A. niger CGMCC0774 culture was concentrated and vanillic acid in the filtrate was bio-converted into vanillin by P. cinnabarinus CGMCC1115. The yield of vanillin reached 2.8 g l(-1) when 5 g l(-1) of glucose and 25 g of HZ802 resin were supplemented in the bioconversion medium. The 13C isotope analysis indicated that delta13C(PDB) of vanillin prepared was much different from chemically synthesized vanillin.