Co(II)-N4 Catalysts for the Coupling of CO2 with Epoxides into Cyclic Carbonates: Catalytic Activity, Computational and Kinetic Studies.

In this study, we synthesized and characterized a series of cobalt(II) complexes bearing linear tetradentate N4 ligands. These Co(II)-N4 complexes proved to be efficient catalysts for the cycloaddition reaction between carbon dioxide and epoxides even at room temperature and 1 bar pressure of carbon dioxide without the need for solvents or cocatalysts. Furthermore, when combined with (triphenylphosphoranylidene)ammonium chloride (PPNCl) as a cocatalyst, the Co-N4 catalysts exhibited an impressive turnover frequency of up to 41,000 h-1 for coupling of epichlorohydrin/CO2. These Co(II)-N4 catalysts were found to have excellent stability and reusability, retaining their catalytic activity after they were recycled seven times. Density functional theory (DFT) calculations provided a comprehensive mechanism for the cycloaddition reaction, indicating that the rate-determining step is the epoxide ring opening, in both the presence and absence of PPNCl. Further kinetic studies allow us to determine the activation parameters (ΔH‡, ΔS‡, and ΔG‡ at 25 °C) of the coupling reaction using the Eyring equation. The Gibbs free activation energy obtained from the kinetic studies was in close agreement with that of the DFT calculations. The substituent effect on the cycloaddition reaction of CO2 with various substituted styrene oxides was also examined for the first time.

Recent progress in adaptive laboratory evolution of industrial microorganisms.

Adaptive laboratory evolution (ALE) is a technique for the selection of strains with better phenotypes by long-term culture under a specific selection pressure or growth environment. Because ALE does not require detailed knowledge of a variety of complex and interactive metabolic networks, and only needs to simulate natural environmental conditions in the laboratory to design a selection pressure, it has the advantages of broad adaptability, strong practicability, and more convenient transformation of strains. In addition, ALE provides a powerful method for studying the evolutionary forces that change the phenotype, performance, and stability of strains, resulting in more productive industrial strains with beneficial mutations. In recent years, ALE has been widely used in the activation of specific microbial metabolic pathways and phenotypic optimization, the efficient utilization of specific substrates, the optimization of tolerance to toxic substance, and the biosynthesis of target products, which is more conducive to the production of industrial strains with excellent phenotypic characteristics. In this paper, typical examples of ALE applications in the development of industrial strains and the research progress of this technology are reviewed, followed by a discussion of its development prospects.

Improving Recognition Accuracy of Pesticides in Groundwater by Applying TrAdaBoost Transfer Learning Method.

Accurate and rapid prediction of pesticides in groundwater is important to protect human health. Thus, an electronic nose was used to recognize pesticides in groundwater. However, the e-nose response signals for pesticides are different in groundwater samples from various regions, so a prediction model built on one region's samples might be ineffective when tested in another. Moreover, the establishment of a new prediction model requires a large number of sample data, which will cost too much resources and time. To resolve this issue, this study introduced the TrAdaBoost transfer learning method to recognize the pesticide in groundwater using the e-nose. The main work was divided into two steps: (1) qualitatively checking the pesticide type and (2) semi-quantitatively predicting the pesticide concentration. The support vector machine integrated with the TrAdaBoost was adopted to complete these two steps, and the recognition rate can be 19.3% and 22.2% higher than that of methods without transfer learning. These results demonstrated the potential of the TrAdaBoost based on support vector machine approaches in recognizing the pesticide in groundwater when there were few samples in the target domain.

The genome of the rice planthopper egg parasitoid wasps Anagrus nilaparvatae casts light on the chemo- and mechanosensation in parasitism.

BACKGROUND: Mymaridae is an ancient insect group and is a basal lineage of the superfamily Chalcidoidea. Species of Mymaridae have great potential for biological control. Anagrus nilaparvatae, a representative species of Mymaridae, is ideal for controlling rice planthopper due to its high rate of parasitism and ability to find hosts efficiently in paddy ridges and fields. RESULTS: Using both PacBio single-molecule real-time and Illumina sequencing, we sequenced and assembled the whole genome of A. nilaparvatae, a first for the family Mymaridae. The assembly consists of 394 scaffolds, totaling 488.8 Mb. The assembly is of high continuity and completeness, indicated by the N50 value of 25.4 Mb and 98.2% mapping rate of Benchmarking Universal Single-Copy Orthologs. In total, 16,894 protein-coding genes in the genome were annotated. A phylogenomic tree constructed for A. nilaparvatae and other 12 species of Hymenoptera confirmed that the family Mymaridae is sister to all remaining chalcidoids. The divergence time between A. nilaparvatae and the other seven Chalcidoidea species was dated at ~ 126.9 Mya. Chemoreceptor and mechanoreceptor genes are important in explaining parasitic behavior. We identified 17 odorant binding proteins, 11 chemosensory proteins, four Niemann-Pick type C2 proteins, 88 olfactory receptors, 12 gustatory receptors, 22 ionotropic receptors and 13 sensory neuron membrane proteins in the genome of A. nilaparvatae, which are associated with the chemosensory functions. Strikingly, there is only one pickpocket receptors and nine transient receptor potential genes in the genome that have a mechanosensory function. CONCLUSIONS: We obtained a high-quality genome assembly for A. nilaparvatae using PacBio single-molecule real-time sequencing, which provides phylogenomic insights for its evolutionary history. The small numbers of chemo- and mechanosensory genes in A. nilaparvatae indicate the species-specific host detection and oviposition behavior of A. nilaparvatae might be regulated by relatively simple molecular pathways.

Surface metrology by multiple-wavelength coherent modulation imaging.

With the rapid progress of advanced manufacturing, three-dimensional metrology techniques that are able to achieve nanometer spatial resolution and to capture fast dynamics are highly desired, for which a snapshot ability and a common-light-path setup are required. Commonly used off-axis holography and phase-shifting interferometry are short in fulfilling those requirements. We studied the suitability and performance of the coherent modulation imaging (CMI) method for metrology applications. Both transparent and reflective samples are measured in visible light experiments. Thanks to its ability to retrieve separate wavefronts at different wavelengths from a single measurement, CMI allows for attaining an enlarged range of measurement free from phase wrapping by utilizing the concept of synthetic wavelength. The CMI method fulfills well the requirements for advanced metrology and can be implemented at any wavelength. We expect it would be a powerful addition to the pool of advanced metrology tools.

Improvement of the catalytic performance of glycerol kinase from Bacillus subtilis by chromosomal site-directed mutagenesis.

Glycerol kinase is the key enzyme in glycerol metabolism, and its catalytic efficiency has an important effect on glycerol utilization. Based on an analysis of the glycerol utilization pathway and regulation mechanism in B. subtilis, we conducted site-directed mutagenesis of the key glycerol kinase gene (glpK) on the chromosome to improve the glycerol utilization efficiency of Bacillus subtilis. Recombinant wild-type Bacillus subtilis glycerol kinase (BsuGlpKWT) and two mutants (BsuGlpKM270I and BsuGlpKS71V) were successfully overexpressed in Escherichia coli BL21(DE3) and purified by Ni-IDA metal chelate chromatography. The specific activity of the BsuGlpKM270I mutant (62.6 U/mg) was significantly higher (296.2%) than that of wild-type BsuGlpKWT (15.8 U/mg). By contrast, the mutant BsuGlpKS71V (4.89 U/mg) exhibited lower (69.1%) activity than BsuGlpKWT, which suggested that variant S71V exhibited reduced catalytic efficiency for the substrate. Furthermore, the mutant strain B. subtilis M270I was constructed using a markerless delivery system, and exhibited a higher specific growth rate (improved by 11.3%, from 0.453 ± 0.012 to 0.511 ± 0.017 h-1) and higher maximal biomass (cell dry weight increased by 16%, from 0.577 ± 0.033 to 0.721 ± 0.015 g/L) than the parental strain with a shortened lag phase (2 ~ 4 h shorter) in M9 minimal medium with glycerol. These results indicate that the mutated glpK resulted in improved glycerol utilization, which has broad application prospects.

Coherent modulation imaging using unknown modulators.

Coherent modulation imaging (CMI) is an effective lensless diffraction imaging method with fast algorithmic convergence and high robustness to data defects. In the reported algorithms for CMI, one important requirement is that the modulator function need to be known a priori; and an additional step for the modulator characterization is required to be carried out in advance by other methods, such as ptychography, which could be cumbersome in practice. Here, we propose an improved algorithm that allows for the transmission function of a completely unknown modulator to be recovered during the same iterative process of image reconstruction. We have verified the method in both simulations and optical experiments. This improvement would turn CMI into a more practical and standalone technique for broader applications in biology and materials science.

A General Strategy for the Construction of Calyciphylline†A-Type Alkaloids: Divergent Total Syntheses of (-)-Daphenylline and (-)-Himalensine†A.

An efficient general strategy for the synthesis of the Daphniphyllum alkaloids via the rapid construction of a common core intermediate has been established, based on which a divergent total synthesis of (-)-daphenylline and (-)-himalensine A has been accomplished in 16 and 19 steps, respectively. The present work features an enantioselective Mg(ClO4 )2 -catalyzed intramolecular amidocyclization to construct the aza-bridged core structure; a Cu-catalyzed intramolecular cyclopropanation and subsequent phosphine-catalyzed Cope-type rearrangement to furnish the himalensine A scaffold; and a one-pot Diels-Alder/aromatization method to assemble the aromatic skeleton of daphenylline.

Total Synthesis of (-)-Daphenylline.

A concise and highly stereoselective total synthesis of the Daphniphyllum alkaloids (-)-daphenylline has been accomplished. The synthesis was started from (S)-carvone and proceeded via a stereoselective Mg(ClO4 )2 -catalyzed intramolecular amide addition cyclization, an intramolecular Diels-Alder reaction to construct the ABCD tetracyclic core architecture, and a Robinson annulation coupled with an oxidative aromatization sequence. Finally, the DF ring system was installed through an intramolecular Friedel-Crafts cyclization. The total synthesis of (-)-daphenylline is achieved in 19 steps in the longest reaction sequence and in 7.6 % overall yield.

N-Heterocyclic carbene-catalyzed annulation of cyclic ß-enamino esters with enals: access to functionalized indolo[2,3-a]quinolizidines.

A novel synthetic approach to functionalized indolo[2,3-a]quinolizidines is developed via an N-heterocyclic carbene (NHC)-catalyzed annulation of cyclic ß-enamino esters with enals . This methodology offers a pathway for quick and efficient construction of an indolo[2,3-a]quinolizidine skeleton which is a core structure of many natural products with diverse bioactivities.

Development an electronic nose to recognize pesticides in groundwater.

Timely detection of Groundwater pollution is essential to protect human health, especially for pesticide pollution. To solve this issue, we proposed a novel solution to realize the prediction of pesticide in groundwater by using the electronic nose (e-nose). The main work of this paper was divided into three steps: 1) checking whether sample was polluted by pesticides, 2) further predicting the pesticide type, brand and pollution degree when the sample was polluted by pesticides, and 3) optimizing the sensor array. Random forest was used to complete the first step, which had the best accuracy and sensitivity of 100 %. Support vector machine was applied to complete the second step, and the accuracy reaching 98.08 %. As for the third step, recursive feature elimination was used to optimize the sensor array. After optimization, the number of sensors was reduced from 26 to 8. In addition, the e-nose developed in this paper was compared with a commercial e-nose. The results showed that the cost of the developed e-nose was much lower than that of the commercial e-nose despite its slightly weaker prediction performance. Thus, this e-nose can be employed to recognize the pesticides in groundwater, and even can be integrated into the while drilling technology to realize the in-situ detection of groundwater.

A Concise Synthesis of (-)-Ambrox.

(-)-Ambrox, a highly prized and commercially significant component of ambergris, finds widespread application in perfumery, cigarettes, cosmetics, and the food industry. Despite considerable attention to this research area over the years, an environmentally friendly and practical method for synthesizing (-)-ambrox has remained elusive. This study presents a succinct and efficient approach to (-)-ambrox synthesis, involving two consecutive alkylations at C-6, followed by an acid-catalyzed cyclization to give bicyclic ketones starting from (R)-carvone. Subsequent reduction, Barton Vinyl Iodide synthesis, alkylation, and an acid-catalyzed cyclization collectively achieved the synthesis of (-)-ambrox with a satisfactory yield of 26.2 %.

Effects of acute aerobic exercise on resting state functional connectivity of motor cortex in college students.

This study intends to inspect the effects of acute aerobic exercise (AE) on resting state functional connectivity (RSFC) in motor cortex of college students and the moderating effect of fitness level. METHODS: 20 high fitness level college students and 20 ordinary college students were recruited in public. Subjects completed 25 min of moderate- and high-intensity acute aerobic exercise respectively by a bicycle ergometer, and the motor cortex's blood oxygen signals in resting state were monitored by functional Near Infrared Spectroscopy (fNIRS, the Shimadzu portable Light NIRS, Japan) in pre- and post-test. RESULTS: At the moderate intensity level, the total mean value of RSFC pre- and post-test was significantly different in the high fitness level group (pre-test 0.62 ± 0.18, post-test 0.51 ± 0.17, t(19) = 2.61, p = 0.02, d = 0.58), but no significant change was found in the low fitness level group. At the high-intensity level, there was no significant difference in the difference of total RSFC between pre- and post-test in the high and low fitness group. According to and change trend of 190 "edges": at the moderate-intensity level, the number of difference edges in the high fitness group (d = 0.58, 23) were significantly higher than those in the low fitness group (d = 0.32, 15), while at high-intensity level, there was a reverse trend between the high fitness group (d = 0.25, 18) and the low fitness group (d = 0.39, 23). CONCLUSIONS: moderate-intensity AE can cause significant changes of RSFC in the motor cortex of college students with high fitness, while high fitness has a moderating effect on the relationship between exercise intensity and RSFC. RSFC of people with high fitness is more likely to be affected by AE and show a wider range of changes.

Preparation of sodium alginate modified silver-metal organic framework and application in citric acid/PVA antimicrobial packaging.

Silver-metal organic framework (Ag@MOF) has exhibited outstanding antimicrobial activity in antimicrobial applications, and reducing the biotoxicity associated with silver has become a research priority. In this study, Ag@MOF was initially modified with sodium alginate (SA) to form SA-Ag@MOF. The results showed that SA could control the release of Ag+, reducing the release by about 8% at 24 h, and the biotoxicity was significantly reduced. Finally, SA-Ag@MOF was applied as an antimicrobial agent in citric acid-modified PVA film to develop a novel composite antimicrobial film. When added at 2 MIC, the CA3-M2 film can effectively inhibit the growth of E. coli and S. aureus, and the inhibition rate has reached 98%. For white radish packaging applications, CA3-M2 film inhibited the growth of surface microorganisms, while ensuring moisture and tissue hardness to extend shelf-life up to 7 days. Overall, the strategy conceived here can be a theoretical basis for novel antimicrobial packaging.

Development of an electronic nose to characterize water quality parameters and odor concentration of wastewater emitted from different phases in a wastewater treatment plant.

For public health consideration, it is important to ensure the wastewater discharged from wastewater treatment plant is within the regulatory limits. This problem can be effectively solved by improving the accuracy and rapid characterization of water quality parameters and odor concentration of wastewater. In this paper, we proposed a novel solution to realize the precisive analysis of water quality parameters and odor concentration of wastewater by the electronic nose device. The main work of this paper was divided into three steps: 1) recognizing wastewater samples qualitatively from different sampling points, 2) analyzing the correlation between electronic nose response signals and water quality parameters and odor concentration, and 3) predicting the odor concentration and water quality parameters quantitatively. Combined with different feature extraction methods, support vector machine and linear discriminant analysis were applied as classifiers to recognize samples at different sampling points, which reported the best recognition rate of 98.83%. Partial least squares regression was applied to complete the second step, and R2 was reaching 0.992. As for the third step, ridge regression was used to predict water quality parameters and odor concentration with the RMSE less than 0.9476. Thus, electronic noses can be applied to determine water quality parameters and odor concentrations in the effluent discharged from wastewater plants.

Exosomal miR-23b from bone marrow mesenchymal stem cells alleviates oxidative stress and pyroptosis after intracerebral hemorrhage.

Our previous studies showed that miR-23b was downregulated in patients with intracerebral hemorrhage (ICH). This indicates that miR-23b may be closely related to the patho-physiological mechanism of ICH, but this hypothesis lacks direct evidence. In this study, we established rat models of ICH by injecting collagenase VII into the right basal ganglia and treating them with an injection of bone marrow mesenchymal stem cell (BMSC)-derived exosomal miR-23b via the tail vein. We found that edema in the rat brain was markedly reduced and rat behaviors were improved after BMSC exosomal miR-23b injection compared with those in the ICH groups. Additionally, exosomal miR-23b was transported to the microglia/macrophages, thereby reducing oxidative stress and pyroptosis after ICH. We also used hemin to mimic ICH conditions in vitro. We found that phosphatase and tensin homolog deleted on chromosome 10 (PTEN) was the downstream target gene of miR-23b, and exosomal miR-23b exhibited antioxidant effects by regulating the PTEN/Nrf2 pathway. Moreover, miR-23b reduced PTEN binding to NOD-like receptor family pyrin domain containing 3 (NLRP3) and NLRP3 inflammasome activation, thereby decreasing the NLRP3-dependent pyroptosis level. These findings suggest that BMSC-derived exosomal miR-23b exhibits antioxidant effects through inhibiting PTEN and alleviating NLRP3 inflammasome-mediated pyroptosis, thereby promoting neurologic function recovery in rats with ICH.

Characteristics of resting state functional connectivity of motor cortex of high fitness level college students: Experimental evidence from functional near infrared spectroscopy (fNIRS).

OBJECTIVE: This study inspects difference of resting state functional connectivity (RSFC) of motor cortex between athletes and ordinary college students and the test-retest reliability of RSFC. METHODS: Twenty high fitness level college students (high fitness group) and 20 ordinary college students (control group) were recruited. The motor cortical blood oxygen signals in resting states were monitored by functional near infrared spectroscopy (fNIRS). RSFCs of brain signals were preprocessed and calculated by FC-NIRS software. RSFC results of test-retest reliability were evaluated by intra-class correlation coefficient (ICC). RESULTS: Total RSFC (HbO signal) was significantly different between high fitness group (0.62 ± 0.04) and low fitness group (0.81 ± 0.04) (p < .05). Significant differences were found between the groups (HbO signal) in 50 edges among the 190 edges of motor cortex (14 edges after FDR corrected). At three hemoglobin concentrations, mean of group-level ICC (C, 1) for total RSFC in two groups was 0.40 ± 0.10, whereas the mean of group-level ICC (C, k) was 0.57 ± 0.11, depicting "fair" reliability. The mean of group-level ICC (C, 1) of 190 "edges" was 0.88 ± 0.06, whereas mean of ICC (C, k) was 0.94 ± 0.03, exhibiting "excellent" reliability. CONCLUSION: Fitness level is the factor causing specific changes in RSFC strength of motor cortex that can be utilized as biomarker for evaluating the fitness level.

Extended coherent modulation imaging for single-shot object retrieval free from illumination artifacts.

Coherent diffraction imaging (CDI) is a rapidly advancing technique, especially for imaging weakly absorptive samples with x-rays or electrons at nano or atomic resolutions. For the study of fast dynamics, single-shot imaging ability is essential. However, reconstructions provided by current single-shot CDI methods are subject to the impairment of illumination artifacts. If one wants to obtain artifact-free object images, flat or well-calibrated illumination would be required. Here, we proposed an extension to coherent modulation imaging (CMI) to realize pure object function retrieval from a single sample measurement. This extension removes the restrictions on the forms of illumination and allows flexibly placing the object between the illumination aperture and the modulator. Our method has been verified in the numerical simulation and visible light experiment, and it could make CMI a practical and powerful microscopy technique.

The Effect and Mechanism of External Use Ulcer Powder on Diabetic Mice.

Objective  Through the preparation of the diabetic mice skin ulcer model, we investigated the effect of Mongolian medicine external ulcer powder (WYK) on the treatment of diabetic skin ulcers and the expression of angiogenesis-related factors such as vascular endothelial growth factor (VEGF) and extracellular regulated protein kinases (ERK). Methods  Thirty male clean Kunming mice were randomly divided into normal control group (group C), diabetic control group (group HC), and diabetic topical ulcer powder group (group HW). After successful modeling in the HC group and the HW group, the rats in the HW group were given external ulcer powder, which was applied to the back of the mice once a day. In addition, the rats in group C and group HC were treated with gentamicin injection external application once a day. The mice were sacrificed on the 3rd, the sixth, and the ninth day of dosing, and samples were taken. The adopted methods included protein immunoblotting (western blot) and reverse transcription-polymerase chain reaction (RT-PCR). The expression differences of angiogenesis-related factors such as VEGF and ERK in the repair process were detected. SPSS 13 software was used to analyze the results of angiogenesis-related factors VEGF and ERK. Results Comparison of VEGF and ERK Contents The serum VEGF content of mice in the HC group was significantly lower than that in the C group on days 3, 6, and 9 (p <0.05). The VEGF content in the HW group was significantly higher than that in the HC group (p <0.05). The content of ERK in serum was basically consistent with that of VEGF. The results of the western blot assay were consistent with those of the RT-PCR assay. Conclusion  WYK can effectively promote the healing of skin ulcer wounds in diabetic mice, accelerate the proliferation of granulation tissue, enrich the contents of capillary blood tubes and collagen fibers, and increase the microvascular content. WYK can improve the expression level of VEGF and ERK in the serum of mice and advance the peak value of protein expression.

Transcriptome analysis and molecular characterization of soluble chemical communication proteins in the parasitoid wasp Anagrus nilaparvatae (Hymenoptera: Mymaridae).

Anagrus nilaparvatae is an important egg parasitoid wasp of pests such as the rice planthopper. Based on the powerful olfactory system of sensing chemical information in nature, A. nilaparvatae shows complicated life activities and behaviors, such as feeding, mating, and hosting. We constructed a full-length transcriptome library and used this to identify the characteristics of soluble chemical communication proteins. Through full-length transcriptome sequencing, splicing, assembly, and data correction by Illumina, we obtained 163.59 Mb of transcriptome data and 501,179 items with annotation information. We then performed Gene Ontology (GO) functional classification of the transcriptome's unigenes. We analyzed the sequence characteristics of soluble chemical communication protein genes and identified eight genes: AnilOBP2, AnilOBP9, AnilOBP23, AnilOBP56, AnilOBP83, AnilCSP5, AnilCSP6, and AnilNPC2. After sequence alignment and conserved domain prediction, the eight proteins encoded by the eight genes above were found to be consistent with the typical characteristics of odorant-binding proteins (OBPs), chemosensory proteins (CSPs), and Niemann-pick type C2 proteins (NPC2s) in other insects. Phylogenetic tree analysis showed that the eight genes share low homology with other species of Hymenoptera. Quantitative real-time polymerase chain reaction (RT-qPCR) was used to analyze the expression responses of the eight genes in different sexes and upon stimulation by volatile organic compounds. The relative expression levels of AnilOBP9, AnilOBP26, AnilOBP83, AnilCSP5, and AnilNPC2 in males were significantly higher than those in females, while the relative expression level of AnilCSP6 was higher in females. The expression levels of AnilOBP9 and AnilCSP6 were significantly altered by the stimulation of ß-caryophyllene, suggesting that these two genes may be related to host detection. This study provides the first data for A. nilaparvatae's transcriptome and the molecular characteristics of soluble chemical communication proteins, as well as an opportunity for understanding how A. nilaparvatae behaviors are mediated via soluble chemical communication proteins.