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β-Fluorinated amine is highly desirable for biological and pharmaceutical science, because replacing a C-H bond with a C-F bond can change the physical and chemical properties of the parent molecule to a large extent but not significantly alter its overall geometry. Herein, the highly stereoselective nucleophilic monofluoromethylation of imines have been developed. It is proposed that the chelated transition state enables the chiral induction by the dynamic kinetic resolution of the chiral α-fluoro carbanions.

Stereochemically defined organofluorine compounds are vital to drug discovery and many applicable catalytic strategies have been introduced for accessing these entities stereoselectively. One approach entails incorporation of a fluorine atom (C-F bond formation) or an organofluorine moiety (e.g., CF

To accurately and quickly predict the open-circuit air-gap magnetic field in interior permanent magnet synchronous machines (IPMSMs), an analytical model based on magnetic equivalent circuit (MEC) method is proposed. The analytical model can provide radial and tangential components of open-circuit magnetic field in the slotless air gap. The radial component is obtained from the MEC model, and the tangential component is obtained from boundary conditions of macroscopic equations. Then, a complex relative air-gap permeance is applied to take the effect of slots into account. As a result, an accurate solution of both radial and tangential components of the flux density in the slotted air gap is obtained. Additionally, the no-load back electromotive force (EMF) and cogging torque are calculated based on the open-circuit air-gap magnetic field. All the analytical results are verified by the finite element (FE) analysis and they are well matched. In the end, a direct measurement experiment of open-circuit air-gap magnetic field is proposed to verify the validity of both radial and tangential open-circuit air-gap magnetic fields.

Aryl fluorosulfonates are developed as a deoxyfluorinating reagent in the transformation of primary and secondary alcohols into the corresponding alkyl fluorides. These reagents feature easy availability, low-cost, high stability and high efficiency. Diverse functionalities including aldehyde, ketone, ester, halogen, nitro, alkene, and alkyne are well tolerated under mild reaction conditions.

In this study, the air gap magnetic field characteristics of external rotor permanent magnet synchronous motors (PMSMs) under both the stator and rotor coordinate systems considering low-order current harmonics and high-order sideband current harmonics are analysed. A direct measurement technique (DMT) for air-gap magnetic field is proposed. First, an analytical model of air gap magnetic field of external rotor PMSMs is established. The spatial order and frequency characteristics of stator/rotor air gap magnetic field are revealed. Then, a 24-pole 27-slot external rotor PMSM is taken as an example. The analytical and finite element (FE) results are compared and analysed. The difference of the spatial order and frequency characteristics between the stator and rotor air gap magnetic field are verified. Next, a new DMT is proposed, which can detect the precise distribution and local microscopic characteristics on the order of 10−1 mm with high resolution. The accuracy of analytical and FE model are verified by the DMT and an indirect experimental test of no-load back electromotive force. Finally, the mechanical challenges of in-wheel motors and the practicablility of DMT for eccentricity detection are further discussed.

A Cu-catalyzed gem-bis(trifluoromethyl)olefination of α-diazo esters, using TMSCF3 as the only fluorocarbon source, has been developed and provides an exquisite method to access gem-bis(trifluoromethyl)alkenes. This unprecedented olefination process involves a carbene migratory insertion into "CuCF3 " to generate the α-CF3 -substituted organocopper species, which then undergoes β-fluoride elimination and two consecutive addition-elimination processes to give the desired products. The key to this efficient one-pot C1 -to-C3 synthetic protocol lies in the controllable double (over single and triple) trifluoromethylations of the gem-difluoroalkene intermediates.

Recently, the role of microRNAs (miRs) in human diseases has been verified. This study was determined to explore the protective effects of microRNA-26a (miR-26a) in steroid-induced osteonecrosis of the femoral head (SONFH) with the involvement of enhancer of zeste homologue 2 (EZH2).Femoral head (FH) samples from SONFH patients and patients with femoral neck fracture were collected, and rat SONFH models were established by Escherichia coli endotoxin combining with large dose steroid pulse assay. The hemorheology, blood lipid, inflammatory factors, and pathologic changes were measured by a series of experiments. Moreover, the detection of osteoblasts, osteoclasts, miR-26a expression, EZH2 expression, osteoprotegerin (OPG) and osteoprotegerin ligand (OPGL), and the apoptosis of osteocytes were conducted. The target relation between miR-26a and EZH2 was clarified by bioinformatics and dual-luciferase reporter gene assay.MiR-26a was poorly expressed, while EZH2 was highly expressed in SONFH, and the elevation of miR-26a could repress EZH2 expression. Elevated miR-26a and reduced EZH2 were able to decelerate the apoptosis of osteocytes, increase osteoblasts, and decrease osteoclasts, resulting in a repression of SONFH progression. Additionally, EZH2 was a target gene of miR-26a. Furthermore, the elevation of EZH2 could reverse the repression of SONFH progression that is induced by elevated miR-26a.We found that up-regulation of miR-26a and knockdown of EZH2 could suppress the development of SONFH, which would contribute to the therapy of SONFH.

Trisubstituted alkenyl fluorides are needed for research in biological chemistry, drug discovery, agrochemical development, and materials science. Among other applications, these entities are secondary amide bond mimics in one stereoisomeric form and induce a peptide turn in the other. Despite notable progress, however, many stereochemically defined trisubstituted fluoro-alkenes either cannot be prepared efficiently, or can be accessed in only one isomeric form. Here, we outline a general solution to this problem by first unveiling a practical, widely applicable, and catalytic strategy for stereodivergent synthesis of olefins bearing a fluoro and chloro terminus. This has been accomplished by cross-metathesis between two trisubstituted olefins, one of which is a purchasable but scarcely utilized trihalo alkene. Subsequent cross-coupling then be used to generate an assortment of trisubstituted alkenyl fluorides. The importance of the advance is highlighted by syntheses of, among others, a fluoro-nematic liquid crystal component, peptide analogs bearing an E- or a Z-amide bond mimic, and all four stereoisomers of difluoro-rumenic ester (anti-cancer).

To explore the ecological risks of trace metals in sediments and their relationship with benthic organisms, 12 trace metals were analyzed and the macrobenthos were identified in the sediments collected from the south coast of Zhejiang province which belongs to the East China Sea. Spatially, the concentrations of most trace metals were high in the estuary, except for Ba and Sr. There was no obvious enrichment for trace metals, except that the concentration of Cd slightly exceeded the coastal background. The ecological risks calculated by the concentrations of Cr, Cd, Cu, Zn, Pb, and Ni in sediments showed that the methods based on sediment quality guidelines could judge the ecological risk more intuitively than the methods based on background value (PN, PLI, RI). The significant correlations between ecological risks and benthos density and biomass revealed the negative impact of trace metals at high concentrations on macrobenthic survival in sediments.

Background It is known that long non-coding RNA (lncRNA) PTCSC3 is involved in thyroid cancer and glioma, but its function in osteoporosis is unknown. The aim of our study was to investigate the role of lncRNA PTCSC3 in osteoporosis. Methods A total of 80 patients with osteoporosis (4 clinical stages) and four corresponding groups of healthy controls were enrolled. Plasma PTCSC3 levels in the 80 osteoporosis patients and 80 healthy volunteers were measured using RT-qPCR. The diagnostic potential of plasma PTCSC3 for osteoporosis was evaluated by ROC curve analysis with healthy volunteers as the true negative cases and corresponding osteoporosis patients as the true positive cases. Results PTCSC3 was upregulated in osteoporosis patients compared with healthy controls. PTCSC3 levels increased with osteoporosis stages increasing, but not with healthy controls aging. PTCSC3 overexpression separated each stage of osteoporosis from corresponding controls. PTCSC3 overexpression promoted while PTCSC3 silencing inhibited osteoblast apoptosis. However, PTCSC3 overexpression and silencing showed no significant effect on osteoclast apoptosis. LncRNA PTCSC3 was upregulated in osteoporosis and negatively regulated osteoblast apoptosis. Conclusion LncRNA PTCSC3 may serve as a potential therapeutic target for osteoporosis.

The progression of osteoarthritis (OA) requires the involvement of lipopolysaccharide (LPS)-induced inflammation, in which circTMOD3 plays an important role. We predicted that circTMOD3 could interact with miR-27a to inhibit LPS-induced chondrocyte apoptosis and explored the interaction between circTMOD3 and miR-27a in OA.Total RNAs were isolated from cartilage tissue samples from both OA patients (n = 62) and controls (n = 62) and subjected to RT-qPCRs to determine circTMOD3 and miR-27a (mature and premature) expression. Subcellular location of circTMOD3 and its interaction with premature miR-27a were analyzed using subcellular fractionation assay and RNA-RNA pulldown assay, respectively. CircTMOD3 was overexpressed in chondrocytes to study its role in miR-27a maturation. The roles of circTMOD3 and miR-27a in LPS-induced chondrocyte apoptosis were analyzed using cell apoptosis assay.CircTMOD3 and premature miR-27a levels were increased while mature miR-27a level was decreased in OA. CircTMOD3 was located in both nuclear and cytoplasm fractions of chondrocytes. CircTMOD3 directly interacted with premature miR-27a and promoted LPS-induced chondrocyte apoptosis, while miR-27a inhibited LPS-induced chondrocyte apoptosis. Moreover, circTMOD3 overexpression suppressed miR-27a maturation and reduced the inhibitory effects of miR-27a on LPS-induced chondrocyte apoptosis.CircTMOD3 suppresses miR-27a maturation in OA to promote chondrocyte apoptosis induced by LPS.

The first catalytic method for diastereo- and enantioselective synthesis of allylic boronates bearing a Z-trisubstituted alkenyl fluoride is disclosed. Boryl substitution is performed with either a Z- or E-allyldifluoride and is catalyzed by bisphosphine/Cu complexes, affording products in up to 99 % yield with >98:2 Z/E selectivity and 99:1 enantiomeric ratio. A variety of subsequent modifications are feasible, and notable examples are diastereoselective additions to aldehydes/aldimines to access homoallylic alcohols/amines containing a fluorosubstituted stereogenic quaternary center.

The previous preparation time of methoxy-grafted kaolinite (Kaol) presents great challenges to the development of Kaol intercalated products. In this study, methoxy-grafted Kaol samples were synthesized via guest displacement of a Kaol–dimethyl sulfoxide intercalation compound (Kaol-DMSO) and a Kaol–urea intercalation compound (Kaol-U) by acid treatment and heating. In the proposed method, the preparation time was dramatically shortened from 7 d to less than 1 h. The prepared methoxy-grafted Kaol showed a basal spacing between 0.86 and 0.90 nm in the X-ray diffraction patterns and the appearance of a vibrational band near 1655 cm−1 in the infrared spectra. These findings indicate that both an acid environment and heating can speed up the preparation of methoxy-grafted Kaol. Adsorbed cations at the edges of Kaol particles form an electrical double layer in solution, and the promoted collision of particles under heating and replacement of hydrogen ions for cations in an acid environment contribute to the degradation of this double layers; expansion of pathways through which methanol can enter the Kaol interlayer spaces also occurs. Further intercalation with dodecyl trimethyl ammonium chloride proved the versatility of the proposed preparation approach for further intercalation.

A new species belonging to the genus Haloschizopera Lang, 1944 (Copepoda, Harpacticoida, Miraciidae, Diosaccinae) was identified based on the samples collected from the East China Sea, near the offshore of Zhejiang Province, East China. The new species is closely related to H. pygmaea Norman & Sccot T., 1905 and shares a combination of the following features: A1 eight-segmented; A2 exp-2 with one distal seta, exp-3 with three setae; P1 endopodal segments subequal, enp-1 not exceeding exp-2; exp-3 of P3 with one inner seta, of P4 with two inner setae. The new species is characterized by the presence of one inner seta on P2 exp-3 of both sexes. It can also be distinguished from its congeners by the characters of female: P5 exopod subcircular, endopodal lobe extending beyond half-length of exopod; genital double-somite ornamented with three dorsolateral rows of spinules on anterior part.

It has great significance to research the effect of intercalated molecules with the same carbon chain and different functional groups on the properties of intercalation compounds since it can reveal the effect of different functional groups on the properties of intercalated compounds without considering the difference of carbon chains. In this study, the intercalation compounds of kaolinite/dodecyl trimethyl ammonium chloride (Kaol-DTAC) and kaolinite/dodecylamine (Kaol-DA) were studied by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetry and differential scanning calorimetry (TG-DSC) analysis, and Scanning electron microscope (SEM). Then the de-intercalation kinetics with different heating rates was investigated, and the optimized the mechanism function for de-intercalation process was calculated. The results showed that the basal spacings of Kaol-DTAC and Kaol-DA intercalation compounds are 3.56 and 4.08 nm, respectively. The DTAC molecules are arranged the Kaol surface in a single layer with an angle of 90° while the DA molecules are tilted towards the Kaol surface in bilayer and the inclination angle is 39.9°, which is due to the different structure between these two type molecules. The SEM showed that the ratio, nanoscrolls length to diameter, of Kaol-DA is larger than that of Kaol-DTAC, and for the yield of nanoscrolls, the former is greater than the latter. Moreover, by using KAS and Ozawa methods, the activation energy (E) of Kaol-DTAC and Kaol-DA were obtained and the average values are 102.44 kJ mol−1 and 130.80 kJ mol−1, respectively. Furthermore, The optimal mechanism function for the intercalation compounds of Kaol-DTAC and Kaol-DA are G(α) = -ln(1-α) and G(α) = [(1-α)(−1/3)−1]2, respectively.

The perception system of unmanned vehicles has developed rapidly in recent years, but in the process of multisensor fusion, a certain sensor's perception error often occurs which causes great errors in the perception results of the entire multi-sensor system and is harmful to human life and property. Therefore, it requires redundant fusion of the objects perceived by the sensors, and sets weights during the fusion process to eliminate sensors with poor detection results. This paper establishes a multi-sensor perception and a dynamic weight distribution and eliminate system. Multi-sensor weight distribution is performed by Kalman tracking variance. Such a system will greatly reduce the errors of the perception system.

Haloschizopera cheni sp. n., was recognized from our latest collections from the East China Sea. The new species is similar to H. abyssi Becher, 1974 but differs from it by the following combined features: baseoendopodal lobe of female P5 with five setae, P2 and P3 enp-3 both longer than enp-1-2 combined, and caudal rami longer than broad. Comparison of all the known species of Haloschizopera was performed. Species in the genus can be divided into four groups by the setal formulae of P3 and P4. The main diagnostic characters of each species are listed and a key to all known species of Haloschizopera is also provided.

Identifying the urban community structure is important for promoting smart city. In contrast to community detection in social network, the urban community construction involves both the information of population flow a nd t he distribution of public services. However, few methods take into account the two factors simultaneously in a reasonable manner. This causes several problems such as isolated nodes and geographical fragmentation in urban planning. To address the challenges of concerning the population flow a nd p ublic s ervices distribution in an unified framework, we formulate the identification problem of urban community structure as graph modularity optimization with constraints on the public services distribution. The combination of hierarchical clustering and node level adjustment strategies is applied, to capture the required information of community structure. In our framework, The attributed graph regards the geographical zones as nodes, the interaction between geographical zones as edges, the distribution of public services as attributes. Moreover, We evaluate our approach by using both the synthetic data set and the real-world data set. Results show the efficacy of the proposed method on identifying the urban community structure.

Though research about sea spiders limited in China seas, a complete checklist has not yet exist so far. After checking recent collections obtained from Shandong, Zhejiang, Fujian and the East China Sea, all these sixty-eight specimens were identified as six species belonged to four families and five genera, including three ones new to China. We described and illustrated them in this study, and also revised all previous records about Chinese pycnogonids and provided a checklist for the presently known forty-one species.

The cumulative number of confirmed cases in the United States exceeded one million on 29 April 2020, becoming the country of the most serious pandemic in the world. We proposed a model to analyze the real situation and follow-up trend of the epidemic in the US.The proposed model divides the epidemic period into two phases, and includes three different categories of transmitters: the latent population, the documented infectious population, and the undocumented infectious population. We use metapopulation network to simulate the spread of the COVID-19 in the US, and apply the Bayesian inference to estimate the key parameters of the model. We also perform component analysis and sensitivity analysis, researching the compositions of the people with COVID-19.The results show that the basic reproduction number in the early period of propagation is 4.06. As of April 13, 2020, only 45% (95% CI: 35% - 73%) of symptom onset cases in the United States were documented. The incubation period of COVID-19 is 10.69 days (95% CI: 10.02 – 11.74). If the current level of interventions is continued, the cumulative number of confirmed cases is expected to reach more than 1.7 million in July and continue to grow.

COVID-19 is now widely spreading around the world as a global pandemic. In this report, we estimate the global tendency of COVID-19 and analyze the associated global epidemic risk, given that the status quo is continued without further measures being taken.The results show that the global R0, excluding China, is estimated to be 2.49 (95% CI: 2.15 – 2.92). The United States, Germany, Italy and Spain have peak values over 100,000. According to dynamical model and cluster analysis, we category the globe into four type regional epicenters of the outbreak: Southeast Asia extending southward to Oceania, the Middle East, Western Europe and North America. Among them, Western Europe will become the major center of the outbreak. The peak values in Germany, Italy and Spain are estimated to be 105,903, 127,283 and 152,539, respectively. The United States is the country with the most serious outbreak trend. Based on the current control measures by Mar. 27, 2020, the peak value in the United States will reach 400,892. Above all, if the current control measures are maintained, the cumulative number of patients worldwide will be 1,442,523 (95% CI: 1,052,577 – 8,981,440). We also estimated the diagnosis rate, recovery rate and infection degree of each country or region, and use clustering algorithm to retrieve countries or regions with similar epidemic characteristics. Different suggestions are proposed for countries or regions in different clusters.