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Background Icaritin is an aglycone of flavonoid glycosides from Herba Epimedii. It has good performance in the treatment of hepatocellular carcinoma in clinical trials. However, the natural icaritin content of Herba Epimedii is very low. At present, the icaritin is mainly prepared from flavonoid glycosides by α-L-rhamnosidases and β-glucosidases in two-step catalysis process. However, one-pot icaritin production required reported enzymes to be immobilized or bifunctional enzymes to hydrolyze substrate with long reaction time, which caused complicated operations and high costs. To improve the production efficiency and reduce costs, we explored α-L-rhamnosidase SPRHA2 and β-glucosidase PBGL to directly hydrolyze icariin to icaritin in one-pot, and developed the whole-cell catalytic method for efficient icaritin production. Results The SPRHA2 and PBGL were expressed in Escherichia coli, respectively. One-pot production of icaritin was achieved by co-catalysis of SPRHA2 and PBGL. Moreover, whole-cell catalysis was developed for icariin hydrolysis. The mixture of SPRHA2 cells and PBGL cells transformed 200 g/L icariin into 103.69 g/L icaritin (yield 95.23%) in 4 h in whole-cell catalysis under the optimized reaction conditions. In order to further increase the production efficiency and simplify operations, we also constructed recombinant E. coli strains that co-expressed SPRHA2 and PBGL. Crude icariin extracts were also efficiently hydrolyzed by the whole-cell catalytic system. Conclusions Compared to previous reports on icaritin production, in this study, whole-cell catalysis showed higher production efficiency of icaritin. This study provides promising approach for industrial production of icaritin in the future.

The first rhodium(i)-catalyzed asymmetric S–H insertion of α-diazoarylacetates with tert-butyl mercaptan using chiral diene as the ligand has been developed.

Additional file 1:Figure S1. HPLC analysis of icariside I and baohuoside I hydrolysis by SPRHA2 and PBGL; Figure S2. HPLC analysis of epimedin A, B, and C hydrolysis by SPRHA2 and PBGL; Figure S3. HPLC analysis of the time course of epimedin C hydrolysis by SPRHA2; Figure S4. Time course of hydrolysis of whole-cell hydrolysis of icariin; Figure S5. SDS-PAGE analysis of pET-pbgl-sprha2 and pET-sprha2-pbgl in E. coli. Table S1. NMR data for standard icaritin and icaritin produced

We present a lattice QCD study of the neutrinoless double beta decay involving light sterile neutrinos. The calculation is performed at physical pion mass using five gauge ensembles generated with 2+1-flavor domain wall fermions. We obtain the low-energy constants gLRππ(mν) with the neutrino mass mν from 0 to 3 GeV. The lattice results are reasonably consistent with the previous interpolation method with a ∼20% deviation at small mν. We provide an explanation on the discrepancy at vanishing neutrino mass. At large mν, a good consistency between our results and the previous lattice determination of g4ππ(μ) is found at μ=mν=3 GeV.

BACKGROUND In recent years, neoadjuvant chemotherapy (NAC) has been increasingly used in patients with resectable colorectal liver metastases. However, the efficacy and safety of NAC in the treatment of resectable colorectal liver metastases (CRLM) are still controversial. AIM To assess the efficacy and application value of NAC in patients with resectable CRLM. METHODS We searched PubMed, Embase, Web of Science, and the Cochrane Library from inception to December 2020 to collect clinical studies comparing NAC with non-NAC. Data processing and statistical analyses were performed using Stata V.15.0 and Review Manager 5.0 software. RESULTS In total, 32 studies involving 11236 patients were included in this analysis. We divided the patients into two groups, the NAC group (that received neoadjuvant chemotherapy) and the non-NAC group (that received no neoadjuvant chemotherapy). The meta-analysis outcome showed a statistically significant difference in the 5-year overall survival and 5-year disease-free survival between the two groups. The hazard ratio (HR) and 95% confidence interval (CI) were HR = 0.49, 95%CI: 0.39-0.61, P = 0.000 and HR = 0.48 95%CI: 0.36-0.63, P = 0.000. The duration of surgery in the NAC group was longer than that of the non-NAC group [standardized mean difference (SMD) = 0.41, 95%CI: 0.01-0.82, P = 0.044)]. The meta-analysis showed that the number of liver metastases in the NAC group was significantly higher than that in the non-NAC group (SMD = 0.73, 95%CI: 0.02-1.43, P = 0.043). The lymph node metastasis in the NAC group was significantly higher than that in the non-NAC group (SMD = 1.24, 95%CI: 1.07-1.43, P = 0.004). CONCLUSION We found that NAC could improve the long-term prognosis of patients with resectable CRLM. At the same time, the NAC group did not increase the risk of any adverse event compared to the non-NAC group.

A method for the highly enantioselective Rh-catalyzed dehydrated arylation of unprotected hemiaminals has been developed, and provided a series of chiral benzosultams bearing trifluoromethylated quaternary stereocenters in high yields with excellent enantioselectivities (up to 99% ee). The synthetic utility was further demonstrated by the facile enantioselective construction of a HIV-1 inhibitor molecule.

Biological diversity plays an important role in the stability of ecosystems. The Mu Us Desert (MUD), located in Northern China, is an aeolian desert. Although it has been governed by a series of ecological restoration programs, the MUD still has limited biological diversity.

The microstructures and mechanical properties of TiAl alloys are directly linked to micro-segregation which cannot be avoided during solidification. So a thorough understanding of the micro-segregation should be a great help to further enhance the mechanical properties of the cast products. Theoretical analysis and experiments have been used to predict the micro-segregation, but it is very difficult to observe and determine the dendritic segregation in the micro region. Phase-field method has been employed for the simulation of dendritic growth. However, due to the complicated quasi-sub regular solution model for Ti-45Al(at.%) alloy, the classic phase-field models have difficulty to deal with the free energy. In this work, a phase-field model by linking thermodynamic calculation was used to simulate solidification dendritic segregation of Ti-45Al alloy for Liquid→Liquid+β(Ti). The free energies of solid phase and liquid phase for Ti-45Al alloy were calculated by Thermo-Calc and then coupled with the phase-field equations. The simulation results show the dendritic morphology and Al content variations between liquid and growing solid phase for Ti-45Al alloy. With the growth of the β(Ti), dendritic segregation is formed in the liquid and solid phases due to the solute partitioning and rejection into the liquid. As a result, the dendrite arms are depleted of Al element, while the inter-dendrites are enriched. The dendritic tip growth velocity decreases with the progress of solidification, whereas the segregation ratio increases.

We present an exploratory lattice QCD calculation of the neutrinoless double beta decay $\ensuremath{\pi}\ensuremath{\pi}\ensuremath{\rightarrow}ee$. Under the mechanism of light-neutrino exchange, the decay amplitude involves significant long-distance contributions. The calculation reported here, with pion masses ${m}_{\ensuremath{\pi}}=420$ and 140 MeV, demonstrates that the decay amplitude can be computed from first principles using lattice methods. At unphysical and physical pion masses, we obtain that amplitudes are 24% and 9% smaller than the predication from leading order chiral perturbation theory. Our findings provide the lattice QCD inputs and constraints for effective field theory. A follow-on calculation with fully controlled systematic errors will be possible with adequate computational resources.

Wind resource assessment has important economic and ecological implications. Many developing countries in arid and semiarid areas are caught in a dilemma between the development of wind energy and the threat of sandy desertification. Sand-driving winds are momentous for both generating wind energy and aeolian research. The estimation for the probability of sand-driving winds has been rarely studied. The ability of the two-parameter Weibull distribution to estimate high wind velocities is questioned and parameters appear to have no practical significance. Drift potential (DP) is a way of evaluating potential sand transport volume by sand-driving winds, but the relationship between DP and the wind energy of sand-driving winds has been rarely studied. In this paper, a function was constructed from the expressions of DP and the two-parameter Weibull probability distribution to improve the estimation of sand-driving winds. This is simple and applicable to arid and semiarid areas worldwide. The mean wind velocity and the mean wind power density at a height of 10 m around the Badain Jaran Sand Sea in China, are in the range between 2.64 and 4.79 m·s−1, and 27.61–165.61 W·m−2, respectively. The mean wind power density of sand-driving winds accounted for half or more of the total mean wind power density. The relationship among DP, the wind power density of sand-driving winds and the probability of sand-driving winds, was proved theoretically. Gentle winds and strong winds are distinguished by the drift wind velocity at which potential sand transport activities (potential lost wind power density) reach their maximum. The scale parameter dominates the mean and median wind velocity, and represents the effect of convection. The shape parameter characterizes the atmospheric stability. These results provide a basis for the wind energy development, improve the understanding of aeolian activities, and have implications for sand control engineering.

Some of the surface on Earth, Mars, Venus, and Titan is covered by ripples, dunes, and other features formed by sand-driving winds. Many developing countries in arid and semiarid areas are caught in a dilemma between the threat of sandy desertification and the development of wind energy. The estimation for the probability of sand-driving winds has been rarely studied. The ability of two-parameter Weibull probability distribution to estimate sand-driving winds is questioned. Sand transport rate is used only for the evaluation of short-term aeolian activities. Drift potential (DP) is an accessible way of evaluating potential sand transport volume by sand-driving winds. However, the relationship among annual sand transport volume, DP and wind energy has been rarely studied. Sand-driving winds can be divided into gentle winds and strong winds, but it is hard to distinguish them and to quantify their effects on aeolian geomorphology. A function was constructed from expressions of sand transport rate and the two-parameter Weibull probability distribution to improve the estimation of sand-driving winds. On this basis, annual sand transport volume was accurately evaluated by sand-driving winds. This is applicable to arid and semiarid areas worldwide. The relationship among annual sand transport volume, DP and wind energy was analyzed from the perspective of dimensional analysis. Gentle winds and strong winds are distinguished by transport wind velocity at which aeolian activities on a sandy underlying surface reach the erosion–deposition balance, and which corresponds to annual maximum sand transport rate. On a sandy underlying surface strong winds control deposition, while gentle winds dominate wind erosion. The transport wind velocity is nearly constant, weakly related to the probability distribution of sand-driving winds. These results provide a basis for an improved understanding of aeolian activities as an important planetary surface process, sand control engineering, and wind energy development.

We present an exploratory lattice QCD calculation of the neutrinoless double beta decay ππ→ee. Under the mechanism of light-neutrino exchange, the decay amplitude involves significant long-distance contributions. The calculation reported here, with pion masses m_{π}=420 and 140 MeV, demonstrates that the decay amplitude can be computed from first principles using lattice methods. At unphysical and physical pion masses, we obtain that amplitudes are 24% and 9% smaller than the predication from leading order chiral perturbation theory. Our findings provide the lattice QCD inputs and constraints for effective field theory. A follow-on calculation with fully controlled systematic errors will be possible with adequate computational resources.

In order to meet the demand of remote monitoring, this paper introduces a method of realizing remote monitoring based on mobile network and embedded system. Related key technologies include building remote monitoring terminal, sending and receiving of SMS, making and sending of MMS. By using S3C6410 hardware platform and Linux OS, as well as GPRS module, and developing phone specific program and interface in control terminal. Users can control and monitor the equipments and working condition in remote terminal or dangerous areas, and query their video images and abnormity information by sending phone SMS or clicking on developed phone interface buttons easily and conveniently.

1, 3-propanediol (1, 3-PD) is biologically synthesized by glycerol dehydratase (GDHt) and 1, 3-propanediol dehydrogenase (PDOR). In present study, the gldABC gene, encoding GDHt from Klebsiella pneumoniae and the yqhD gene, encoding PDOR isoenzyme from E.coli BL21 were cloned and co-expressed in E.coli JM109 using plasmid pSE380. The over-expressed recombinant enzymes were purified by nickel-chelate chromatography combined with gel filtration to study the properties. Optimal temperature and pH of recombinant GDHt with specific activity of 85.8 U/mg were 45 °C and 9.0; and optimal temperature and pH of recombinant YqhD with specific activity of 80.0 U/mg were 37 °C, 7.0. The microbial conversion of 1,3-PD from glycerol by this recombinant E. coli strain was studied and the production of 1,3-PD was about 28.0 g/l.

As an emerging two-dimensional (2D) material, monolayer molybdenum disulfide films show excellent electrical and optical properties and have aroused great interest due to their potential applications in electronics and optoelectronics. In this paper, we review our works about molybdenum disulfide films in the past few years. Chemical vapor deposition (CVD) is a convenient and low-cost method to synthesize 2D materials. By oxygen-assisted CVD, the wafer-scale highly-oriented monolayer molybdenum disulfide films and large single-crystal monolayer molybdenum disulfide on various substrates have been prepared epitaxially. Preparation of high-quality monolayer molybdenum disulfide films is the key to measure its intrinsic properties and realize its large-scale applications. Besides the preparation of high-quality materials, the optimizing of transfer technique and fabrication technique are of equal importance for improving the properties of electronic and optoelectronic devices. Water-assisted lossless transfer, patterned peeling, structural change and local phase transition of monolayer molybdenum disulfide films pave the way for preparing and optimizing the functionalized devices. For example, water-assisted transfer and patterned peeling provide methods of preparing molybdenum disulfide samples with clean surfaces and interfaces. Phase transition in the contact area of field-effect transistor reduces the contact resistance effectively, which improves the electrical performance. In addition, the heterojunctions of molybdenum disulfide and other 2D materials show novel electrical and optical properties. As for the functional devices, ultrashort-channel field-effect transistors, integrated flexible thin film transistors, and humidity sensor array have been realized with monolayer molybdenum disulfide films. A grain boundary widening technique is developed to fabricate graphene electrodes for ultrashort-channel monolayer molybdenum disulfide transistors. Field-effect transistors with channel lengths scaling down to 4 nm can be realized reliably and exhibit superior performances, such as the nearly Ohmic contacts and excellent immunity to short channel effects. Furthermore, monolayer molybdenum disulfide films show excellent electrical properties in the measurement of integrated flexible thin film transistors. Under a uniaxial stain of 1%, the performance of the device shows no obvious change, revealing not only the high quality of CVD-grown molybdenum disulfide films, but also the stabilities of these flexible thin film transistor devices. Molybdenum disulfide humidity sensor array for noncontact sensation also shows high sensitivity and stability. Mobility and on/off ratio of the devices in the array decrease linearly with the relative humidity increasing, leading to a high sensitivity of more than 104. The study of monolayer molybdenum disulfide films is universal and instructive for other 2D transition metal dichalcogenides.

In the field of the application of modern HF communication, much more attention is paid to the technology of HF OFDM modulation-demodulation. HF channel is the frequency and time selective fading channel. To reliably receive information, HF receiver must estimate real-time channel parameters to equalize. A performance comparing with the channel parameters estimate methods based on the first-order linear interpolation, Gaussian interpolation, Cubic interpolation and DFT interpolation is analyzed. Simulation results show that a better performance will gain when using DFT interpolation channel estimate method in HF OFDM system.

To clone the members of ACC synthase gene family in sugarcane, two degenerate oligonucleotide primers were designed, coding for two conservative acid regons in ACC synthase protein family. PCR amplification was performed on sugarcane DNA template, which produced three fragments that were 1041 bp (Sc-ACS1), 1345bp (Sc-ACS2) and 1707bp (Sc-ACS3), respectively. Analyses by using the program of BLAST on NCBI GenBank database showed that the polypeptide sequences of their coding regions highly matched with the family of ACC synthase genes from grass plants, the identity of their nucleotide sequence reached 88% to 98%. The nucleotide sequence of both Sc-ACS1 and Sc-ACS3 in opposite directons shared a homology of 98% but they were less similar to Sc-ACS2 (49%). Alignment and phylogenetic analyses of the amino acid sequence deduced from these fragments and sequences of ACC synthase from other plants in the GenBank. According to the ACC synthase protein family, the intron was excluding and the three sequences coded 326,242 and 310 amino acids, respectively, which spanned 67%, 50% and 64.6%, respectively, of the putative whole sequence in length. The putative amino acid sequence of both Sc-ACS1 and Sc-ACS3 shared significant identity to other ACC synthases (53–96%) and they were more similar to the sequences in grass plant species (80% with Zea mays Zm-ACS6, 75% withAsparagus officinaland andPhyllostachs edulis, and 73% withOryza sativa OS-ACS1) than to Sc-ACS2 (45–49%). The amino acid sequence of both Sc-ACS1 and Sc-ACS3 in opposite directions shared a homology of 96%. Based on the Northern analysis of the three ACC synthase gene members isolated it was concluded that accumulation of Sc-ACS1 RNA increased moderately in the sugarcane leaves treated with dark-growing condition, ethrel, IAA, LiCl and cold-stress, but not expressed while treated with BA and light- growing condition. The Sc-ACS2 was only expressed in the ethrel treatment, whereas Sc-ACS3 did not express in any treatment. The present study provided a new evidence of ethylene regulation in sugarcane at molecular level, as part of the regulation mechanism of ethylene to the growth of sugarcane plants.

With the rapid development of wireless network, demand for the spectrum accessing increases dramatically. However, if selfish users can access the spectrum arbitrarily, it may lead to serious interference problem for the network. In our paper, the spectrum owner in the network regulates the spectrum accessing of radio devices. It uses a new kind of auction called VARYVER to efficiently allocate the channels. We prove that VARYVER auction not only guarantee the truthfulness but also does well in ensuring the fairness among nodes in our multi-hop, multi-channel network. Spectrum owner first determines the winners of the auction, then uses some algorithms to determine the users of the channel based on the information VARYVER collect. Finally, spectrum owner charges the users and redistribute the revenue of the network to both winners and users. Simulation results show that our LP Algorithm does well in both maximizing the throughput of our network and ensuring the fairness among nodes while the Greedy Algorithm may cause data congestion in multi-hop network.

Guidance is very important for one in an unfamiliar or even totally new place, especially staying in town with many crossed streets or lanes, typically for a traveler during his/her tourism. Mobile phone with camera has been taken as a useful tool for navigation for travellers. Pictures or video taken by mobile phones are used to identify traveller's position with method of visual localization. Localization of traveller is the basic step for navigation, but an exact and easy guidance could be more important and practical. This paper takes a full consideration of navigation based on mobile visual localization and provide traveller with an exact and easy guidance method. Mobile user captures a few photos or a short video around him/her, for example with his/her cell phone, and then sends it or them to a remote server via wireless internet. Remote server extracts visual features and matches them to pictures database to determine the traveller's position. Given a destination, Navigation Situation is generated and calculate proper rout between traveller's position and destination, then return traveller with a series of pictures marked with an arrow indicating the correct crossing and left/right turn should be taken. Following these marked pictures, traveller can get the expected place and it's just like labyrinth guidance.

OFDM system performance is sensitive to frequency offset and timing error than single-carried system. In this paper, a novel joint time and frequency synchronization method is proposed based on PN sequences for OFDM. A special training symbol of OFDM is constructed with the PN sequence and the differentially coded PN sequence in the transmitter, in the receiver, the training symbol is differentially decoded to get the time synchronization with the autocorrelation property of PN sequence before the frequency offset is estimated, then it eliminates the effect of polarity of the received signal with local PN sequence to get the fine frequency offset estimation combined with ML method. The performance of time synchronization is excellent in low SNR, the maximum frequency offset estimation range can be up to one half of overall signal bandwidth, the simulation results show that the proposed method is effective.

Using computer-aided design of single-site mutations, three amino acid residues determined by changes in folding free energy between wild-type (wt) and mutant proteins were exchanged to enhance the stability of pyruvate formate-lyase (PFL). The mutant enzymes were tested for properties such as optimum temperature, optimum pH, kinetic parameters, and stability to temperature. There were two mutant variants, Glu336Cys and Glu400Ile, that exhibited increased thermostability as compared to the wt enzyme. The melting temperatures (T(m), the temperature at which 50% inactivation occurs after heat treatment for 20 min) of Glu336Cys and Glu400Ile increased by 3.7 and 2.2 respectively. They also showed an increase in half life of about 1.80 and 2.21-fold, whereas Ala273Cys showed a slight decrease as compared with the wt enzyme.

Based on the principle of the pathway engineering, a novel pathway of producing glycerol was built in E. coli. The gpd1 gene encoding glycerol 3-phosphate dehydrogenase and the hor2 gene encoding glycerol 3-phosphatase were cloned from Saccharomyces cerevisiae, respectively. The two genes were inserted into expression vector pSE380 together. A recombinant plasmid pSE-gpd1-hor2 containing polycistron was constructed under the control of the strong trc promoter. Then it was transformed into E. coli BL21. The result showed the recombinant microorganism GxB-gh could convert glucose to glycerol directly. And the recombinant microorganism GxB-gh was incubated to produce glycerol from D-glucose in the fermentor. The maximal concentration of glycerol was 46.67g/L at 26h. Conversion rate of glucose was 42.87%. The study is about "green" producing glycerol by recombinant microorganism and is also useful for further working in recombining microorganism of producing 1,3-propanediol.

A new open reading frame in Thermobifida fusca sequenced genome was identified to encode a new trehalose synthase, annotated as "glycosidase" in the GenBank database, by bioinformatics searching and experimental validation. The gene had a length of 1830 bp with about 65% GC content and encoded for a new trehalose synthase with 610 amino acids and deduced molecular weight of 66 kD. The high GC content seemed not to affect its good expression in E. coli BL21 in which the target protein could account for as high as 15% of the total cell proteins. The recombinant enzyme showed its optimal activities at 25 degrees and pH 6.5 when it converted substrate maltose into trehalose. However it would divert a high proportion of its substrate into glucose when the temperature was increased to 37 degrees, or when the enzyme concentration was high Its activity was not inhibited by 5 mM heavy metals such as Cu2+, Mn2+, and Zn2+ but affected by high concentration of glucose. Blasting against the database indicated that amino acid sequence of this protein had maximal 69% homology with the known trehalose synthases, and two highly conserved segments of the protein sequence were identified and their possible linkage with functions was discussed.