Carrier-free immobilized enzymatic reactor based on CipA-fused carbonyl reductase for efficient synthesis of chiral alcohol with cofactor self-sufficiency.

In this study, based on the self-assembly strategy, we fused CipA with carbonyl reductase LXCARS154Y derived from Leifsonia xyli by gene coding, and successfully performed the carrier-free immobilization of LXCARS154Y. The immobilized enzyme was then characterized using scanning electron microscope (SEM), dynamic light scattering (DLS) and fourier transform infrared spectroscopy (FTIR). Compared with the free enzyme, the immobilized LXCARS154Y exhibited a 2.3-fold improvement in the catalytic efficiency kcat/km for the synthesis of a chiral pharmaceutical intermediate (R)-3,5-bis(trifluoromethyl)phenyl ethanol ((R)-BTPE) by reducing 3,5-bis(trifluoromethyl)acetophenone (BTAP). Moreover, the immobilized enzyme showed the enhanced stability while maintaining over 61 % relative activity after 18 cycles of batch reaction. Further, when CipA-fused carbonyl reductase was employed for (R)-BTPE production in a continuous flow reaction, almost complete yield (97.0 %) was achieved within 7 h at 2 M (512.3 g/L) of BTAP concentration, with a space-time yield of 1717.1 g·L-1·d-1. Notably, we observed the retention of cofactor NADH by CipA-based enzyme aggregates, resulting in a higher total turnover number (TTN) of 4815 to facilitate this bioreductive process. This research developed a concise strategy for efficient preparation of chiral intermediate with cofactor self-sufficiency via continuous flow biocatalysis, and the relevant mechanism was also explored.

A bio-sensing surface with high biocompatibility for enhancing Raman scattering signals as enabled by a Mo-Ag film.

Biological surface-enhanced Raman scattering (SERS) sensing is dependent on the properties of the sensing surface. For the biological sensing surfaces for SERS, the hydrophilicity, biocompatibility and signal sensitivity are pivotal. Hence, a hard bimetallic Mo-Ag film was developed by a magnetron sputtering technique, and the surface morphology could be controlled by the relative contents of Mo and Ag. The Mo-Ag film has better hydrophilicity than the pure Ag film, which could be beneficial for cell attachment during biological SERS sensing. Moreover, the cell test shows that the Mo-Ag film exhibits good cytocompatibility with MC3T3-E1 cells, which shows potential for SERS detection in vivo. The high surface roughness of the Mo-Ag film is a fascinating feature for enhancing Raman scattering signals. Through depositing a thin film of Mo-Ag on a glass surface with a size of 0.5 × 0.5 cm2, a sensing chip of SERS could be produced. High sensitivity and excellent signal reproducibility were acquired. The sensitivity was down to 10-10 mol L-1 for malachite green and 10-9 mol L-1 for thiram, and the relative standard deviation value was lower than 7.0%. Moreover, bacteria were detected by employing the Mo-Ag film chip, and the difference in signal uniformity between molecules and bacteria is illustrated. In summary, depositing the Mo-Ag film on the surface of sensors could be an effective strategy for biomedical SERS sensing.

MetaDecoder: a novel method for clustering metagenomic contigs.

BACKGROUND: Clustering the metagenomic contigs into potential genomes is a key step to investigate the functional roles of microbial populations. Existing algorithms have achieved considerable success with simulated or real sequencing datasets. However, accurately classifying contigs from complex metagenomes is still a challenge. RESULTS: We introduced a novel clustering algorithm, MetaDecoder, which can classify metagenomic contigs based on the frequencies of k-mers and coverages. MetaDecoder was built as a two-layer model with the first layer being a GPU-based modified Dirichlet process Gaussian mixture model (DPGMM), which controls the weight of each DPGMM cluster to avoid over-segmentation by dynamically dissolving contigs in small clusters and reassigning them to the remaining clusters. The second layer comprises a semi-supervised k-mer frequency probabilistic model and a modified Gaussian mixture model for modeling the coverage based on single copy marker genes. Benchmarks on simulated and real-world datasets demonstrated that MetaDecoder can be served as a promising approach for effectively clustering metagenomic contigs. CONCLUSIONS: In conclusion, we developed the GPU-based MetaDecoder for effectively clustering metagenomic contigs and reconstructing microbial communities from microbial data. Applying MetaDecoder on both simulated and real-world datasets demonstrated that it could generate more complete clusters with lower contamination. Using MetaDecoder, we identified novel high-quality genomes and expanded the existing catalog of bacterial genomes. Video Abstract.

Modeling the complete spatiotemporal spread of the COVID-19 epidemic in mainland China.

OBJECTIVES: The novel coronavirus (COVID-19) epidemic is reaching its final phase in China. The epidemic data are available for a complete assessment of epidemiological parameters in all regions and time periods. METHODS: This study aims to present a spatiotemporal epidemic model based on spatially stratified heterogeneity (SSH) to simulate the epidemic spread. A susceptible-exposed/latent-infected-removed (SEIR) model was constructed for each SSH-identified stratum (each administrative city) to estimate the spatiotemporal epidemiological parameters of the outbreak. RESULTS: We estimated that the mean latent and removed periods were 5.40 and 2.13 days, respectively. There was an average of 1.72 latent or infected persons per 10,000 Wuhan travelers to other locations until January 20th, 2020. The space-time basic reproduction number (R0) estimates indicate an initial value between 2 and 3.5 in most cities on this date. The mean period for R0 estimates to decrease to 80%, and 50% of initial values in cities were an average of 14.73 and 19.62 days, respectively. CONCLUSIONS: Our model estimates the complete spatiotemporal epidemiological characteristics of the outbreak in a space-time domain. These findings will help enhance a comprehensive understanding of the outbreak and inform the strategies of prevention and control in other countries worldwide.

Ta@Ag Porous Array with High Stability and Biocompatibility for SERS Sensing of Bacteria.

The reliable sensing of bacteria by surface-enhanced Raman scattering (SERS) technology necessitates a rational design of a substrate with high sensitivity, stability, and minimal invasion. Hence, a bimetallic Ta@Ag film with a porous array is developed by the magnetron sputtering technique and the structure could be controlled by a Ta dopant. A porous array connected by ligaments with compact granular nanoprotrusions is a fascinating substrate for SERS sensing. It makes steady SERS signals even in harsh chemical environments due to its high structural and chemical stability. The configuration of binary Ta@Ag has higher surface free energy than that of pure Ag, and the strong bactericidal activity of Ag is suppressed efficiently. Using E. coli as a model pathogen, the Ta@Ag porous film could maintain the long-term survival rate of E. coli up to 95% and a limit of SERS detection of E. coli down to 102 CFU/mL, which is measured by the standard colony-counting method. In sum, this work provides a promising strategy to fabricate a corrosion-resistant and biocompatible bimetallic Ta@Ag film with a porous array for the SERS sensing of microbial cells.

Star-Shaped Molecules as Dopant-Free Hole Transporting Materials for Efficient Perovskite Solar Cells: Multiscale Simulation.

On the reported TCP-OH (See Scheme 1), other two star-shaped molecules are theoretically designed by replacement of side group of TCP-OH by N,N-di(4-methoxyphenyl)aniline for TPAP-OH and oxygen-bridged triarylamine for TBOPP-OH. The core group, phenol, is kept in three molecules. Their potential to be hole transport material in perovskite solar cells without dopants is evaluated by multiscale simulations. The properties of isolated molecules are estimated by the frontier molecular orbital, absorption spectrum, and hole mobility. After that, the HTM@CH3 NH3 PbI3 adsorbed system is studied to consider the influence of adsorption on HTM performance. Besides the primary judgment, the glass transition temperature is also simulated to determine the stability of amorphous film. Not only the chemical stability is evaluated but also the amorphous film stability is considered. The latter is almost neglected in previous theoretical studies to evaluate the properties of HTMs. The performance of a designed molecule is evaluated from both the isolated molecules and HTM@CH3 NH3 PbI3 adsorbed system including aforementioned items, which is favorable to build reliable structure-property relationship.

[Effects of five Chinese herbs on human demodicid mites in vitro].

OBJECTIVE: To research the effects of five Chinese herbs of Artemisia argyi, Chimonanthus praecox, Agastache rugosa, pine needles and Osmamthus fragrans on human demodicid mites in vitro. METHODS: The human demodicid mites were acquired with the cellophane tape method. The ethanol heat reflux extractions were carried out on the 5 kinds of Chinese herbs to be studied and Stemona sessilifolia as the positive control, so as to get the herbal extracts. Next, the drug administration was carried out to the demodicid mites, and the inhibitory or killing effects of the 6 kinds of Chinese herbs above mentioned on the vermiform mites were observed under a microscope. It was considered to be dead when the bodies of the demodicid mites stopped moving. Besides, the duration from drug administration to death of the vermiform mites was recorded. RESULTS: Artemisia argyi, Chimonanthus praecox and Agastache rugosa could effectively inhibit and kill human demodicid mites. The effect of Artemisia argyi and Agastache rugosa was similar to the effect of Stemona sessilifolia, and the effect of Chimonanthus praecox was weaker than Stemona sessilifolia's effect. Among them, Agastache rugosa took a relatively short time (4.60 min ± 1.66 min) min and Osmamthus fragrans took the longest time (114.65min ± 80.14min) to Demodex folliculorum; Whereas, Artemisia argyi took the shortest time (3.56min ± 1.92 min) min and Osmamthus fragrans took the longest time (194.24min ± 134.96 min) min to Demodex brevis. CONCLUSIONS: The effects of Artemisia argyi and Agastache rugosa on human demodicid mites are similar to that of Stemona sessilifolia. The effects of Chimonanthus praecox and pine needles are weaker than that of Stemona sessilifolia. Osmamthus fragrans has no acaricidal effect.

Genome-wide analysis of WRKY transcription factors in wheat (Triticum aestivum L.) and differential expression under water deficit condition.

BACKGROUND: WRKY proteins, which comprise one of the largest transcription factor (TF) families in the plant kingdom, play crucial roles in plant development and stress responses. Despite several studies on WRKYs in wheat (Triticum aestivum L.), functional annotation information about wheat WRKYs is limited. RESULTS: Here, 171 TaWRKY TFs were identified from the whole wheat genome and compared with proteins from 19 other species representing nine major plant lineages. A phylogenetic analysis, coupled with gene structure analysis and motif determination, divided these TaWRKYs into seven subgroups (Group I, IIa-e, and III). Chromosomal location showed that most TaWRKY genes were enriched on four chromosomes, especially on chromosome 3B. In addition, 85 (49.7%) genes were either tandem (5) or segmental duplication (80), which suggested that though tandem duplication has contributed to the expansion of TaWRKY family, segmental duplication probably played a more pivotal role. Analysis of cis-acting elements revealed putative functions of WRKYs in wheat during development as well as under numerous biotic and abiotic stresses. Finally, the expression of TaWRKY genes in flag leaves, glumes, and lemmas under water-deficit condition were analyzed. Results showed that different TaWRKY genes preferentially express in specific tissue during the grain-filling stage. CONCLUSION: Our results provide a more extensive insight on WRKY gene family in wheat, and also contribute to the screening of more candidate genes for further investigation on function characterization of WRKYs under various stresses.

[Investigation on Demodex infection status and influencing factors in medical students in Wuhu City].

OBJECTIVE: To investigate the Demodex infection status and influencing factors in medical students in Wuhu City. METHODS: The mite specimens were collected by the cellophane tape method, and the influencing factors were investigated through the questionnaires. RESULTS: A total of 316 medical students were surveyed, 117 students were infected with Demodex mite, and the total infection rate was 37.03%. There was no significant difference between the male and female in the infection rate (χ2 = 0.00, P > 0.05). Of the 117 infected cases, the infection rate of simple Demodex folliculorum was 51.28%, the infection rate of simple Demodex brevis was 24.79%, and the rate of mixed infections was 23.93%. The rate of the mild infection (83.76%) was significantly higher than that of the moderate infection (12.82%) and that of the severe infection (3.42%). The infection rate in the forehead was the highest (29.41%). Among the students with the oily skin, the infection rate of Demodex mite was related to sex. The infection rate of simple Demodex brevis in the male (3.70%) was lower than that in the female (16.42%) (χ2 = 6.92, P < 0.05), while the rate of the mixed infections in the male (17.28%) was higher than that in the female (4.48%) (χ2 = 5.91, P < 0.05). The infection rate of facial skin with symptoms (51.80%) was higher than that of normal facial skin (33.05%) (χ2 = 9.14, P < 0.01). There was no significant difference between the infection rate of Demodex mite and the living habits and other factors. CONCLUSIONS: There is some infection of Demodex in the medical students. The infection rate of facial skin with symptoms is higher than that of the normal facial skin. So we should strengthen the prevention and treatment of Demodex infection in medical students.

Theoretical investigations of the structures and electronic spectra of 8-hydroxylquinoline derivatives.

The spectroscopic properties of 8-hydroxyquinoline derivatives are theoretically investigated by means of density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. The target molecules are divided into two groups: group (I): (E)-2-(2-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)vinyl)quinolin-8-ol (A), together with corresponding potential reaction products of A with acetic acid, i.e., (E)-2-(2-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)vinyl)quinolin-8-yl acetate (AR1), and (E)-2-(2-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)vinyl)-8-hydroxyquinolinium (AR2); group (II): (E)-2-(2-(1-(4-chlorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl)vinyl)quinolin-8-ol (B), as well as potential reaction products of B with acetic acid, i.e., (E)-2-(2-(1-(4-chlorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl)vinyl)quinolin-8-yl acetate (BR1), and (E)-2-(2-(1-(4-chlorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl)vinyl)-8-hydroxyquinolinium (BR2). The geometries are optimized by B3LYP and M06 methods. The results indicate that product molecules tend to be effectively planar compared with reactants. Subsequently, UV absorption spectra are simulated through TD-DFT method with PCM model to further confirm the reasonable products of two reactions. AR2 and BR2 are identified as the target molecules through the experimental spectra for the real products. It is worth noting that the maximum absorption wavelengths of compounds AR2 and BR2 present prominent red shift compared the initial reactants A and B, respectively, which should be ascribed to the enhancive planarity of products that mentioned above and the decreased HOMO-LUMO energy gap. Geometric structures and optical properties for corresponding compounds are discussed in detail.

Theoretical studies on structures and electronic spectra of linear free radicals CnH (n=5-12).

The B3LYP, CAM-B3LYP, and coupled cluster CCSD(T) calculations have been utilized to determine the equilibrium structures of linear carbon radicals CnH (n=5-12) in their ground states, as well as the CASSCF method used to optimize the ground and selected low-lying excited states. DFT-calculations show that even-n radicals C2nH have polyacetylene-like structures with significant single-triple bond length alternation, whereas the odd-numbered analogues C2n+1H exhibit a trend from polyacetylene-like characters into cumulenic-like arrangement towards C ends along the carbon chains. The stabilities of the system under study have been evaluated by analyses of the vibrational frequencies and incremental binding energies. For the whole CnH (n=5-12) series, the vertical excitation energies and oscillator strengths have been calculated at the CASPT2/cc-pVTZ level of theory. At the B3LYP optimized geometries, the lowest 1(2)Δ←X2Π transitions for C5H and C7H occur at 2.36 and 2.14 eV, respectively, comparing well with the observed values of 2.33 and 2.09 eV. Moreover, the strongest 2(2)Π←X2Π transitions for C2nH (n=3-6) are predicted to be at 2.39, 2.00, 1.80, and 1.64 eV, respectively, which are in agreement with the experimental observations. Additionally, the possible dissociation channels and the fragmentation energies of CnH (n=5-12) series are discussed in the paper.

Zinc supplementation inhibits lipid peroxidation and the development of atherosclerosis in rabbits fed a high cholesterol diet.

Developing atherosclerotic lesions in hypercholesterolemic rabbits are depleted in zinc, while iron accumulates. This study examined the influence of zinc supplementation on the development of atherosclerosis and used isotope dilution gas chromatography-mass spectrometry techniques to measure biomarkers of oxidative lipid damage in atherosclerotic rabbit aorta. Our previous method for F(2)-isoprostane measurement was adapted to include the quantitation of cholesterol oxidation products in the same sample. Two groups of New Zealand white rabbits were fed a high cholesterol (1% w/w) diet and one group was also supplemented with zinc (1 g/kg) for 8 weeks. Controls were fed a normal diet. Zinc supplementation did not significantly alter the increase in total plasma cholesterol levels observed in animals fed high cholesterol. However, in cholesterol-fed animals zinc supplementation significantly reduced the accumulation of total cholesterol levels in aorta which was accompanied by a significant reduction in average aortic lesion cross-sectional areas of the animals. Elevated levels of cholesterol oxidation products (5,6-alpha and beta cholesterol epoxides, 7beta-hydroxycholesterol, 7-ketocholesterol) in aorta and total F(2)-isoprostanes in plasma and aorta of rabbits fed a cholesterol diet were significantly decreased by zinc supplementation. Our data indicate that zinc has an antiatherogenic effect, possibly due to a reduction in iron-catalyzed free radical reactions.

Promotion of atherogenesis by copper or iron--which is more likely?

Iron levels increase in atherosclerotic lesions in cholesterol fed-rabbits and play a role in atherosclerosis. We investigated whether copper also rises. Male New Zealand White rabbits were fed high-cholesterol diets for 8 weeks. After sacrifice, lesion sizes were determined, and elemental analyses of the lesion and unaffected artery wall performed using nuclear microscopy. Unlike iron, lesion copper is decreased by about half compared with the unaffected artery wall, and much less copper than iron is present. Our data suggest that iron may be more likely to play a role in the promotion of atherosclerosis than copper.

Zinc supplementation decreases the development of atherosclerosis in rabbits.

Developing atherosclerotic plaques in cholesterol-fed rabbits are enriched in iron but depleted in zinc. In order to examine further the role of zinc, New Zealand White rabbits were fed a high-cholesterol 1% (w/w) diet with zinc (1 g/kg) supplementation for 8 weeks. After the 8-week period, the average atherosclerotic lesion cross-sectional areas in the aortas of the animals fed with the zinc supplement were significantly decreased (1.0 mm2) compared with lesion areas of the animals fed only on the high-cholesterol diet (3.1 mm2). Using nuclear microscopy, a technique for mapping and measuring trace elements in tissue sections, lesion zinc levels (24 ppm) were observed to be unchanged in the zinc-fed rabbits compared to controls. However, average lesion Fe levels in the zinc-fed group were measured at 32 ppm, whereas in the control group the average Fe levels were significantly higher at 43 ppm (P = 0.03). Our data support the concept that zinc may have an antiatherogenic effect by decreasing iron levels in the lesion, possibly leading to inhibition of iron-catalyzed free radical reactions.

Auditory-evoked cerebral oxygenation changes in hypoxic-ischemic encephalopathy of newborn infants monitored by near infrared spectroscopy.

Recent neuronal activation studies have demonstrated the presence of regional cerebral blood flow (rCBF) increases in response to neuronal activation in normal newborns. In the present study, using near infrared spectroscopy (NIRS), we evaluated the evoked cerebral blood oxygenation (CBO) changes in hypoxic-ischemic encephalopathy (HIE) of newborns. We studied 20 normal newborns and 22 HIE newborns; mild HIE (n=9), moderate HIE (n=7), and severe HIE (n=6). The babies were from 1 to 3 days postdelivery. We measured the concentration changes of deoxyhemoglobin (Deoxy-Hb), oxyhemoglobin (Oxy-Hb), and total hemoglobin (Total-Hb) induced by auditory stimulation in the frontal lobes. The normal and HIE groups showed different Oxy-Hb and Total-Hb responses. In normal newborns, 19 out of 20 normal subjects showed increases of Oxy-Hb and Total-Hb, whereas 14 out of 22 subjects showed decreases of Oxy-Hb and Total-Hb during the stimulation (chi(2)=19.95, p<0.001). In addition, there was a strong negative correlation between HIE severity and changes of Total-Hb (r=-0.73, p<0.001). These results suggest that infants with HIE have decreased rCBF in the frontal lobes during auditory stimulation.