Search

Two new monoterpenoid indole alkaloids, taberibogines A and B (1 and 2), together with four known ones (3–6), were isolated from the stems of Tabernaemontana bovina. The structures of these compounds were elucidated using comprehensive spectroscopic analysis and quantum chemistry computational methods. Compounds 1–2 were evaluated for their inhibitory effects on LPS-induced NO production in RAW 264.7 macrophages.

Monovalent metal ions play an essential role in some enzyme reactions. Due to the loose interactions, identifying the critical residues interacting with monovalent metal ions based on a molecular dynamic (MD) analysis is still a challenge. In this study, we first defined the enrichment factor (Eaa) and the dwell time (td) to describe the interactions with metal ions in each enzyme residue during MD analysis. A "sandwich-like" solvent box for MD analysis was then constructed to avoid the interference of the initial position of metal ions. Finally, a bioinformatics tool, CityApps, was developed to facilitate the automatization of MD analysis and the calculation of the interaction parameter. Using the tool, the key residues (D191, Q272, and N329) responsible for K+-mediated activation of a methyl parathion hydrolase (MPH) from Pseudomonas sp. WBC-3 were identified based on Eaa, td, and RMSF differences. Ala mutation showed that the mutant D191A/Q272A/N329A was difficult to be activated by 1 M K+. In addition, Q272A showed a 176.19 % increase in specific activity compared to the wild MPH type. Our results indicate that CityApps developed here could be an effective tool for identifying enzyme residues interacting with monovalent metal ions and those residues that are critical for catalytic reaction.

The application of hydrogen direct-injection enrichment improves the performance of gasoline Wankel rotary engine, and the hydrogen injection strategy has a significant impact on combustion, knock, and emissions. The Z160F Wankel rotary engine was used as the investigated compact engine, and the simulation model was developed using CONVERGE software. The combustion, knock and emissions characteristics of the engine were studied with the different mass flow of hydrogen injection, i.e., the trapezoid, wedge, slope, triangle and rectangle type of gas injection rate shape. In the numerical simulations, the in-cylinder pressure oscillations were monitored using monitoring points, and the knock index (KI) was used as an evaluation indicator. The study revealed that the gas injection rate shape significantly affected the mixture of hydrogen and air, thus impacting combustion, knock and emissions. When the injection rate shape was rectangle, the flame speed was faster, the peak pressure in the cylinder was higher, and the corresponding crank angle was earlier, which led to higher pressure oscillations in the cylinder and larger KI. Based on the rectangle injection rate shape, the KI decreased by 75.81%, 33.47%, 26.46% and 76.58% for trapezoid, wedge, slope, and triangle, respectively, and the indicated mean effective pressure increased by 15.68%, 5.07%, 0.56% and 14.98%, respectively. Due to the small difference in maximum temperature, which resulted in very little variation in nitrogen oxides for each injection rate shape, the total hydrocarbon emissions of the trapezoid and triangle injection rate shape was high due to the delayed combustion phase. This paper provides a solution for direct hydrogen injection to improve the combustion, knock and emissions behavior of the rotary engine.

An effective protocol is proposed to generate three-atom singlet states in an atom-cavity coupled system. By analyzing the interactions between atoms and cavity, we first derive a Hamiltonian with the target singlet state approximatively being one of its eigenstates. Then, to drive the system from the initial state to the target state, we design the waveform of the external laser fields by Lyapunov control method. The parameter selections are discussed based on the experimentally available parameters, and the influence of the errors and decoherence on the fidelity are analyzed. Numerical simulations indicate that the protocol can not only generate singlet-state with high speed, but also possess great robustness against operational errors and decoherence. Therefore, the protocol may be useful in the singlet-state-based quantum information processing.

The 12 mm-thick Ti–6Al–4V (TC4) titanium alloy plates were welded using keyhole tungsten inert gas (K-TIG) welding at various heat inputs. The microstructure, grain boundary (GB) characteristics and mechanical properties of the weld metal zone (WMZ) were analyzed. The test results show that the K-TIG welds are well formed, and no obvious defects are observed when the heat input is 2.30–2.62 kJ/mm. When the heat input gradually increases, α laths increase in length, and α′ phase and residual β phase are reduced. The electron backscatter diffraction (EBSD) test results indicate that the high-angle GB proportion in the WMZ increases with the increase of heat input. The tensile strength of the WMZ gradually decreases and the elongation of the WMZ increases when the heat input increases from 2.30 to 2.62 kJ/mm. The impact toughness of the WMZ increases as the heat input increases.

A novel binary composite of (Pb,La)(Zr,Sn)O3–AgNbO3 (PLZS–AN) was designed and constructed to optimize the comprehensive energy storage properties. Upon the addition of AN, superior energy storage performance was observed, especially in the actual charge–discharge process. With the addition of 0.01 AN (AN1) (i.e., a PLZS to AN ratio of 0.99 : 0.01), the energy storage efficiency (η) was significantly improved (>85%) accompanied by a slight attenuation in the energy storage density (Wrec) of 10.81 J cm−3. AN2 exhibits comprehensively superior energy storage properties (9.36 J cm−3, 89.09%) at the same time. Moreover, the actual discharge performance is obviously enhanced, exhibiting a giant current density of 3218.20 A cm−2 (AN3) and an excellent power density of 556.30 MW cm−3 (AN1). The superiority, in terms of the energy storage, of the above-mentioned two compositions originates from the difficultly in inducing FEII (Cm2m). The addition of AN results in a change in the phase transition temperature of AFE1(O)–AFE2(O), thereby modulating the room temperature construction of the phase structure. The as-obtained excellent discharge performances are the highest reported to date, and the proposed binary composite method provides important guidance for the subsequent design of antiferroelectric ceramics with high comprehensive performance.

Glycogen synthase kinase-3β (GSK-3β) is a highly conserved multifunctional serine/threonine (Ser/Thr) protein kinase widely expressed in many tissues. GSK-3β inhibitors could be used in the treatment of human key diseases, such as cancer, Alzheimer’s disease, Parkinson’s disease, inflammation, type-II diabetes, and so on, due to the multi-role of GSK-3β in the hepatic glycolysis regulation, cell signaling pathways, and phosphorylation of various proteins. Recently, sets of diverse GSK-3β inhibitors have been prepared, and biologically evaluated in vitro and in vivo in different screening models. This review summarizes the latest developments in GSK-3β inhibitors unclosed from 2015 to 2019, including their structure–activity relationship and bioactivity studies.

The emergence of New Delhi metal beta-lactamase (NDM-1)-producing bacteria and their worldwide spread pose great challenges for the treatment of drug-resistant bacterial infections. These bacteria can hydrolyze most β-lactam antibacterials. Unfortunately, there are no clinically useful NDM-1 inhibitors. In the current work, we manually collected NDM-1 inhibitors reported in the past decade and established the first NDM-1 inhibitor database. Four machine-learning models were constructed using the structural and property characteristics of the collected compounds as input training set to discover potential NDM-1 inhibitors. In order to distinguish between high active inhibitors and putative positive drugs, a three-classification strategy was introduced in our study. In detail, the commonly used positive and negative divisions are converted into strongly active, weakly active, and inactive. The accuracy of the best prediction model designed based on this strategy reached 90.5%, compared with 69.14% achieved by the traditional docking-based virtual screening method. Consequently, the best model was used to virtually screen a natural product library. The safety of the selected compounds was analyzed by the ADMET prediction model based on machine learning. Seven novel NDM-1 inhibitors were identified, which will provide valuable clues for the discovery of NDM-1 inhibitors.

In this paper, the effects of direct water injection (WI) on characteristics of combustion and emission for a hydrogen (H2)-fueled spark ignition (SI) engine were experimentally investigated. The experiments conducted under different amounts of water injection (AWI) and varied water injection timing (WIT). The experimental results showed that in-cylinder pressure decreased, indicated thermal efficiency (ITE) increased, and the flame development (CA0-10) and propagation (CA10-90) periods prolonged when AWI raised. When AIW grew to 4.5 mg/cycle, Nitrogen oxides (NOx) expelled from the original engine decreased by 53.7% when excess air ratio (λ) was 1.15. Early WIT had positive effects on the reduction of NOx emissions. When WIT retarded, in-cylinder pressure increased, ITE decreased and CA0-10 and CA10-90 shortened, NOx emissions rapidly increased.

Discovery of novel multifunctional inhibitors targeting acetylcholinesterase (AChE) has becoming a hot spot in anti-Alzheimer's disease (AD) drug development. In the present study, four potent small molecule inhibitors (A01, A02, A03 and A04) of AChE with new chemical scaffold were identified. Inhibitor A03 displayed the most potent inhibition activity on AChE at enzymatic level with IC50 value of 180 nM, and high selectivity towards AChE over butyrylcholinesterase (BChE) by more than 100-fold. The binding modes of compounds A01-A04 were carefully analyzed by molecular docking and molecular dynamics (MD) simulation to provide informative clues for further structure modification. Finally, the anti-amyloid beta (Aβ) aggregation and neuroprotective activity were also well investigated. Our findings highlighted the therapeutic promise of AChE inhibitors A01-A04 for AD treatment.

Thrombin inhibition therapy is a practical strategy to reduce thrombotic and cardiovascular risks via blocking the formation of blood clots. This study aimed to identify naturally occurring thrombin inhibitors from licorice (one of the most popular edible herbs), as well as to investigate their inhibitory mechanisms. Among all tested licorice constituents, licochalcone A was found as the most efficacious agent against human thrombin (IC50 = 7.96 μM). Inhibition kinetic analyses demonstrated that licochalcone A was a mixed inhibitor against thrombin-mediated Z-Gly-Gly-Arg-AMC acetate hydrolysis, with a Ki value of 12.23 μM. Furthermore, mass spectrometry-based chemoproteomic assays and molecular docking simulations revealed that licochalcone A could bind to human thrombin at both exosite I and the catalytic site. In summary, our findings demonstrated that the chalcones isolated from licorice were a new class of direct thrombin inhibitors, also suggesting that licochalcone A was a promising lead compound for developing novel anti-thrombotic agents.

Nucleic acid diagnosis is a method that diagnoses human conditions and diseases by directly exploring the existing states or defects of nucleic acids using theoretical and technical approaches from molecular biology. The detected genes are either endogenous (the body's own genes) or exogenous (such as viruses and bacteria). The former is used to diagnose genetic lesions and the latter is used to diagnose pathogenic infections. Fluorescent hybridization probes based on the principles of fluorescence resonance energy transfer (FRET) and the complementary pairing of nucleic acids have been widely used in nucleic acid detection due to their high sensitivity and selectivity, ease of design and synthesis. These probes have been extensively studied and modified for different applications. Traditional fluorescent hybridization probes include molecular beacons (MBs) and binary probes (BPs). Many new fluorescent hybridization probes have been derived to improve the sensitivity of the traditional probes by adjusting their structure, combined with amplification techniques and novel nanomaterials. This review describes the applicability and advantages of various hybridization probes that utilize novel and inventive designs.

A rapid and sensitive method is described for measuring perchlorate (ClO4−), chlorate (ClO3−), chlorite (ClO2−), bromate (BrO3−), and iodate (IO3−) ions in natural and treated waters using non-suppressed ion chromatography with electrospray ionization and tandem mass spectrometry (NS-IC-MS/MS). Major benefits of the NS-IC-MS/MS method include a short analysis time (12 minutes), low limits of quantification for BrO3− (0.10 μg L−1), ClO4− (0.06 μg L−1), ClO3− (0.80 μg L−1), and ClO2− (0.40 μg L−1), and compatibility with conventional LC-MS/MS instrumentation. Chromatographic separations were generally performed under isocratic conditions with a Thermo Scientific Dionex AS16 column, using a mobile phase of 20% 1 M aqueous methylamine and 80% acetonitrile. The isocratic method can also be optimized for IO3− analysis by including a gradient from the isocratic mobile phase to 100% 1 M aqueous methylamine. Four common anions (Cl−, Br−, SO42−, and HCO3−/CO32−), a natural organic matter isolate (Suwannee River NOM), and several real water samples were tested to examine influences of natural water constituents on oxyhalide detection. Only ClO2− quantification was significantly affected – by elevated chloride concentrations (>2 mM) and NOM. The method was successfully applied to quantify oxyhalides in natural waters, chlorinated tap water, and waters subjected to advanced oxidation by sunlight-driven photolysis of free available chlorine (sunlight/FAC). Sunlight/FAC treatment of NOM-free waters containing 200 μg L−1 Br− resulted in formation of up to 263 ± 35 μg L−1 and 764 ± 54 μg L−1 ClO3−, and up to 20.1 ± 1.0 μg L−1 and 33.8 ± 1.0 μg L−1 BrO3− (at pH 6 and 8, respectively). NOM strongly inhibited ClO3− and BrO3− formation, likely by scavenging reactive oxygen or halogen species. As prior work shows that the greatest benefits in applying the sunlight/FAC process for purposes of improving disinfection of chlorine-resistant microorganisms are realized in waters with lower DOC levels and higher pH, it may therefore be desirable to limit potential applications to waters containing moderate DOC concentrations (e.g., ∼1–2 mgC L−1), low Br− concentrations (e.g.

A three-component, metal-free radical cascade iodonitrosylative cyclization reaction was described. The nitroso radical was generated from tert-butyl nitrite and triggered the radical addition/cyclization/iodination/oxidation sequences. A variety of 1,6-enynes were tested and proved to be compatible, delivering various highly functionalized hetero- and all-carbon cycles and nitro and vinyl C-I bonds containing pyrrolidines, tetrahydrofuran, and cyclopentane in moderate to excellent isolated yields.

A triazole (1-(p-tolylthio)-1H-1,2,3-triazole-4-carboxylic acid, TTC) film was prepared via an in-situ click-assembling reaction between tosyl azide (TA) and propiolic acid (PA) on Cu, Cu2O and CuO substrates. Its surface wettability, antibacterial activity and anticorrosion ability were evaluated by surface characterizations, antibacterial testing and electrochemical measurements. The modified-Cu2O film exhibits the best overall performance. The anticorrosion protection efficiency of the modified-Cu2O film for copper is 91.1%. The modified-Cu2O film shows a superior hydrophobicity with a contact angle of 137° and it also has the best antibacterial activity. The FT-IR and surface analysis (SEM and XPS) reveal that the excellent anticorrosion ability of the modified-Cu2O film is mainly due to the massive TTC film assembled on its surface. The large amount of TTC also contributes to the best hydrophobicity and antibacterial activity. The theoretical calculations show that the TTC film is formed via the horizontal adsorption of a triazole ring and O atoms in the TTC molecule.

Hydroxypropyl (HP) starches are used as thickeners and stabilizers in foods. The properties of the etherified starches are dependent on the degree of hydroxypropylation. The objective of this study was to develop an improved acid hydrolysis method to degrade and solubilize HP starches for determining HP content in modified starches by 1H NMR. The effects of acid (DCl) concentration and temperature on hydrolysis and solubilization of hydroxypropylated starches were examined. The optimal conditions proposed to hydrolyze HP starches were 10% starch solid content, 3.5% (wt%) DCl in D2O as the solvent, sodium acetate as an internal standard, and heating at 90 °C for 1 h. Optionally, 6% (v/v) TFA-d may be added as the water-peak shifting reagent. Six hydroxypropylated starches and two cross-linked and hydroxypropylated starches were hydrolyzed with this improved acid method, and the results of the HP content were in agreement with those from an enzyme-catalyzed method.

Corn bran hemicellulose was extracted from de-oiled and de-starched corn bran using 0.3 M alkali at 120 °C. Following neutralization, ethanol (75%) precipitation, dialysis, protein digestion, re-precipitation in ethanol, and freeze-drying, purified corn fiber gum (PCFG) was obtained in overall yield of 45.96%. PCFG gave a single peak by high performance size exclusion chromatograph, and had average molecular weight of 296 kDa. Monosaccharide composition, methylation, and GC–MS analysis indicated that PCFG was comprised of three monosaccharides, arabinose (araf), xylose (xylp) and galactose (galp) with the following linkage: t-araf, 17.09%; 1,3-araf, 12.43%; t-xylp, 16.13%; 1,4-xylp, 11.57%; 1,3,4-xylp, 26.02%; 1,2,3,4-xylp, 10.46%; t-galp, 6.37%. Partial acid hydrolysis suggested that arabinofuranose sugar residues were substituted onto a 1,4-linked xylan backbone. Extensive 1D and 2D NMR spectroscopy was used to identify and confirm the following linkages: t-xylp, 1,2,3,4-β-D-xylp, t-α-L-araf, 1,2-α-L-araf and 1,4-β-D-xylp. Several other linkage fragments were also deduced: t-araf→2-araf→2-O-(1,3,4-xyl), t-araf→2-araf→3-O-(1,2,4-xyl), t-araf→2-araf→3-araf, and t-gal→2-ara.

Waxy, normal, and high-amylose maize starches were acetylated to various degrees of substitution (DS) in aqueous medium. A stepwise addition of acetic anhydride enhanced reaction efficiency and DS was in the order of high-amylose maize starch (DS 1.72) > waxy maize starch (DS 1.60) > normal maize starch (DS 1.03) when 240% (w/w) acetic anhydride was added. Starch acetates were further fully esterified to DS 3.0 using acetic anhydride-d6 or propionic anhydride to analyze position of acetyl groups on anhydroglucose unit (AGU) by 1H NMR. Regioselective 2-O-acetyl starches were produced when the DS was lower than 0.14. At DS 1, the distribution of acetyl groups was ca. 44%, 32%, and 24% at C-2, C-3, and C-6 positions, respectively, regardless of amylose content. Deuterated acetyl group was a preferred secondary substituent over propionyl group in subsequent 1H NMR analysis because it resulted a clean spectrum without interference from propionyl methyl protons.

Octenylsuccinic anhydride (OSA)-modified starches were prepared in granular form from waxy maize starch at two levels (3% and 9%, based on the weight of starch) of OSA reagent. The distribution of OS groups at five positions within a single starch granule was determined by Raman microspectroscopy. OSA-modified starch had one additional peak at 1670 cm−1, indicative of the carbonyl group in OS group bound to starch molecules. For each Raman spectrum obtained at a given position on a starch granule, the ratio of the band areas of carbonyl (1679 cm−1) to starch (2910 cm−1) was calculated. The highest level of OS groups was found on the granular surface. However, the level of OS groups in the center of granules also was high and nearly equal to that on the surface. The regions between the surface and the hilum of the waxy maize starch granules had reduced OS substitution.

Four new compounds, including two butenolides (1 and 2), an arborinane-type triterpenoid (3) and a phenylethanoid glycoside (4), along with the known triterpenoids (5–17) and phenylethanoid glycosides (18–29), were isolated from whole plants of Plantago depressa. The structures of the isolated compounds were elucidated by comprehensive spectroscopic analyses and were evaluated for their anti-inflammatory or antiradical activities. Our results underlined that, among compounds 1–17, only compound 16 inhibited lipopolysaccharide-induced NO production with an IC50 equal to 5.33 ± 0.51 μM. All phenylethanoid glycosides (4, 18–29) were evaluated for their antiradical activity with a DPPH radical scavenging bioassay and showed high to moderate effect (IC50 from 2.70 to 51.51 μM).

Silicon oxycarbide (SiOC) materials are considered as a promising high capacity anode for next-generation Li-ion batteries. However, the rapid capacity fading and poor cycling stability often occur in the SiOC materials with high Si content. In this work, an effective and facile strategy is reported to construct nanocomposites of MnO/SiOC, in which SiOC acts as buffer agent and conductive matrix, while MnO contributes to the major reversible capability. Microalgae (Chlorella) serves as both biological template and carbon source to synthesize SiOC microspheres with the assistance of supercritical CO2 fluid, then rice-like MnO nanoparticles are tightly embedded in the SiOC matrix through the heavy metal ion bio-sorption behavior of Chlorella. As anode materials for Li-ion batteries, the C/MnO/SiOC composites exhibit high reversible capacity of 770 mAh g−1 after 200 cycles at a current density of 100 mA g−1 with excellent cycling stability and great rate capability. This work provides a novel strategy to fabricate SiOC-based high capacity anode materials for advanced Li-ion batteries.

A series of new indole-3-acetic acid (IAA)-tacrine hybrids as dual acetylcholinesterase (AChE)/butyrylcholinesterase (BChE) inhibitors were designed and prepared based on the molecular docking mode of AChE with an IAA derivative (1a), a moderate AChE inhibitor identified by screening our compound library for anti-Alzheimer's disease (AD) drug leads. The enzyme assay results revealed that some hybrids, e.g. 5d and 5e, displayed potent dual in vitro inhibitory activities against AChE/BChE with IC50 values in low nanomolar range. Molecular modeling studies in tandem with kinetic analysis suggest that these hybrids target both catalytic active site and peripheral anionic site of cholinesterase (ChE). Molecular dynamic simulations and Molecular Mechanics/Poisson-Boltzmann Surface Area (MM-PBSA) calculations indicate that 5e has more potent binding affinity than hit 1a, which may explain the stronger inhibitory effect of 5e on AChE. Furthermore, their predicted pharmacokinetic properties and in vitro influences on mouse brain neural network electrical activity were discussed. Taken together, compound 5e can be highlighted as a lead compound worthy of further optimization for designing new anti-AD drugs.

With the development of robotic vision technology, applications of visual guided robotic grasping and assembly become more and more widespread in aerospace industry. Self-plugging rivet with complex structures plays an important role in connection of aircraft and spacecraft. This paper focus on identification and location of scattered self-plugging rivets for robot automatic grasping. In this paper, the structure and rivet measurement elements are analyzed and the calculation method of grasping point and angle is introduced, firstly. Secondly, the rivet image processing method based on multiple corrosion and expansion operators is proposed, and rivet contour is obtained initially. Thirdly, in order to determine the grasping angle uniquely, a method of multiple times subtraction with mask image is proposed. In addition, the rivets’ skeleton lines are rebuilt with binocular and the effects of threshold value are studied. The reconstruction and gripping accuracy is verified through a standard board with marker points. Vision-guided robot rivet grasping experiment succeed finally. Experiment results show our detection algorithm is effective and the grasping system can completely satisfy the industrial requirements.

Traditional subway construction technology still mainly involves on-site poured concrete construction, which causes many social and environmental problems and at the same time is not compatible with the modern concept of resilient city construction and sustainable development. A new prefabricated subway station construction technology can effectively solve many of the problems caused by traditional cast-in-situ technology and provide for the sustainable development of subway construction programmes. As an important part of an urban lifeline system, the seismic performance of subway stations has always attracted much attention. This paper focuses on the dynamic response of the single-ring structure of a prefabricated subway station under horizontal earthquake shaking. Using the commercial finite element software ABAQUS, numerical analysis models of two large-scale underground structures have been developed: the single-ring structure of a prefabricated subway station and the traditional cast-in-situ subway station. Under the same earthquake action, there are obvious differences between the prefabricated structure and the traditional cast-in-place structure. Compared to the seismic response of traditional cast-in-situ structures, the ground acceleration response of the prefabricated structure is slightly reduced, the overall deformation is slightly increased, the maximum internal force and stresses are significantly reduced, the internal force transmission path is changed, and the area of influence in the surrounding soil is significantly reduced. Comprehensive comparative analysis shows that the single-ring structure of the prefabricated subway station has good deformation resistance and excellent mechanical properties under horizontal earthquake shaking and the overall seismic performance meets the design requirements. Finally, the seismic response characteristics and energy dissipation advantages of the prefabricated single-ring structure are discussed. The research conclusions will provide useful references for resilient city construction and sustainable urban development.

Citric acid is the world’s largest consumed organic acid and is widely used in beverage, food and pharmaceutical industries. Aspergillus niger is the main industrial workhorse for citric acid production. Since the release of the genome sequence, extensive multi-omic data are being rapidly obtained, which greatly boost our understanding of the citric acid accumulation mechanism in A. niger to a molecular and system level. Most recently, the rapid development of CRISPR/Cas9 system facilitates highly efficient genome-scale genetic perturbation in A. niger. In this review, we summarize the impact of systems biology on the citric acid molecular regulatory mechanisms, the advances in metabolic engineering strategies for enhancing citric acid production and discuss the development and application of CRISPR/Cas9 systems for genome editing in A. niger. We believe that future systems metabolic engineering efforts will redesign and engineer A. niger as a highly optimized cell factory for industrial citric acid production. Electronic supplementary material The online version of this article (10.1186/s12934-019-1064-6) contains supplementary material, which is available to authorized users.

Land cover change detection (LCCD) based on bitemporal remote sensing images has become a popular topic in the field of remote sensing. Despite numerous methods promoted in recent decades, an improvement on the usability and performance of these methods has remained necessary. In this paper, a novel LCCD approach based on the integration of $k$ -means clustering and adaptive majority voting ( $k$ -means_AMV) techniques have been developed. The proposed $k$ -means_AMV method consists of three major techniques. First, to utilize the contextual information in an adaptive manner, an adaptive region around a central pixel is constructed by detecting the spectral similarity between the central pixel and its eight neighboring pixels. Second, when the extension for the adaptive region is terminated, the $k$ -means clustering method is applied to determine the label of each pixel within the adaptive region. Finally, an existing AMV technique is used to refine the label of the central pixel of the adaptive region. When change magnitude image (CMI) is scanned and processed in this manner, the label of each pixel in the CMI can be refined and the binary change detection map can be generated. Three image scenes related to different land cover change events are adapted to test the effectiveness and performance of the proposed $k$ -means_AMV approach. The results show that the proposed $k$ -means_AMV approach demonstrates better detection accuracies and visual performance than that of the several extensively used methods.

The performance of Pd/Pt-based electrocatalysts is closely correlated with their surface structure, size and composition. Herein, we prepared uniformly distributed ultra-small PtPd alloyed nanoparticles (PtPd ANPs, ∼5 nm) within a robust three-dimensional nitrogen-doped reduced graphene oxide (3D-N-rGO) under hydrothermal conditions. l -Hydroxyproline was employed as reductant, N-doping and swelling agent for 3D-N-rGO. The size and shape of graphene hydrogels were easily adjusted by controlling the reaction temperature, and the formation mechanism was discussed in details. Then, the product was explored for ethylene glycol oxidation reaction (EGOR) and hydrogen evolution reaction (HER). The catalytic activity of PtPd ANPs/3D-N-rGO towards HER is close to the state-of-the-art Pt/C catalyst, and better than that of Pt/C in the case of EGOR. This study has shed some lights on the universal approach to develop next-generation catalysts, which is of great significance for direct alcohol fuel cells.

A two-dimensional Ni(II) coordination polymer with an alternating arrangement of left- and right-handed helical chains based on a novel 3,5-bis(1′,2′,4′-triazol-1′-yl)pyridine rigid ligand was proposed as a novel and efficient molecular catalyst for water oxidation.

Dehydrogenases are widely employed as biocatalysts for the production of optically pure chemicals under mild conditions. Most dehydrogenases are nicotinamide cofactor (NADPH or NADH)-dependent oxid...

To enhance solar energy utilization efficiency, goal-directed design of architectures by combining nanocomponents of radically different properties, such as plasmonic, upconversion, and photocatalytic properties may provide a promising method to utilize the most energy in sunlight. In this work, a new strategy was adopted to fabricate a series of plasmonic Ag nanoparticles decorated GdF3:Yb3+, Er3+, Tm3+-core@porous-TiO2-shell ellipsoids, which exhibit high surface area, good stability, broadband absorption from ultraviolet to near infrared, and excellent photocatalytic activity. The results showed that photocatalytic activities of the as-obtained photocatalysts was higher than that of pure GdF3:Yb3+, Er3+, Tm3+ and GdF3:Yb3+, Er3+, Tm3+@TiO2 samples through the comparison of photodegradation rates of methyl orange under UV, visible, and NIR irradiation. The possible photocatalytic mechanism indicates that hydroxyl radicals and superoxide radical play a pivotal role in the photodegradation. Furthermore, the materials also showed exceptionally high stability and reusability under UV, visible, and NIR irradiation. All these results reveal that core–shell hierarchical ellipsoids exhibit great prospects for developing efficient solar photocatalysts.

The click chemistry reaction between 2, 2-dimethylethynyl carbinol (MBY) and tosyl azide (TA) was used to form triazole films on copper surface. The effect of cuprous ions on the assembled films was investigated by the electrochemical measurements. The assembled films have the best protection efficiency of 93.8%. The attack of chloride ions gives out cuprous ions to catalyze the formation of compact triazole films. It shows that the assembled films have an anodic passivation role, and suppress the anodic corrosion reactions evidently. The role of cuprous ions on the films formation during the assembling process is discussed.

In this study, indolyl-1,2,4-oxidizable derivatives were synthesized and in vitro evaluated as new class of non-competitive α-glucosidase inhibitors. Most of the compounds showed better inhibitory activity than reference drug (acarbose), with compound 35 being the most potent inhibitor. Kinetic analysis indicated that compound 35 had non-competitive inhibition on α-glucosidase, and fluorescence quenching experiment confirmed the direct binding of 35 to α-glucosidase. Besides, some selected compounds had no effect on cell viability of human normal hepatocyte (LO2) and human liver cancer (HepG2) cells. Thus, this work provides a new chemotype for developing novel drugs against type 2 diabetes.

In recent years, machine learning is applied in the bioinformatics and medical fields to analyze relationships among biological features and behaviors. However, it is difficult to discover the significant features of large-scale datasets. A novel feature extraction method called bioinformatic explainable deep neural network (BioExpDNN) is proposed to filter the critical features with strong influences on the dataset and to explain the interaction of features. In the practical experiments, this study adopted three biomedical science datasets from the UCI (University of California, Irvine) Machine Learning Repository: (1). Cryotherapy Data Set (CDS) contains 6 attributes and 2 classes (i.e., recovery and non-recovery); (2). Cervical Cancer Behavior Risk Data Set (CCBRDS) consists of 18 attributes and 2 classes (i.e., cervical cancer patient and healthy body); (3). Heart Failure Clinical Records Data Set (HFCRDS) includes 12 clinical attributes and 2 classes (i.e., death and life). In comparison results, extracted features were considered as inputs of a classifier based on deep neural network for classification. The classification accuracy was selected as an evaluation factor to evaluate the performance of feature extraction methods. The experimental results showed that the classification accuracies of CDS, CCBRDS, and HFCRDS were 92.59%, 100%, and 78.9%, respectively.

α-Glycosidase inhibitors could inhibit the digestion of carbohydrates into glucose and promote glucose conversion, which have been used for the treatment of type 2 diabetes. In the present study, 52 candidates of α-glycosidase inhibitors were selected from commercial Specs compound library based on molecular docking–based virtual screening. Four different scaffold compounds (7, 22, 37, and 44) were identified as α-glycosidase inhibitors with IC50 values ranging from 9.99 to 35.19 μM. All these four compounds exerted better inhibitory activities than the positive control (1-deoxynojirimycin, IC50 = 52.02 μM). The fluorescence quenching study and kinetic analysis revealed that all these compounds directly bind to α-glycosidase and belonged to the noncompetitive α-glycosidase inhibitors. Then, the binding modes of these four compounds were carefully investigated. Significantly, these four compounds showed nontoxicity (IC50 > 100 μM) toward the human normal hepatocyte cell line (LO2), which indicated the potential of developing into novel candidates for type 2 diabetes treatment.

We present a scheme to realize precise discrimination of chiral molecules in a cavity. Assisted by additional laser pulses, cavity fields can evolve into different coherence states with contrary-sign displacements according to the handedness of molecules. Consequently, the handedness of molecules can be read out with homodyne measurement on the cavity, and the successful probability is nearly unity without very strong cavity fields. Numerical results show that the scheme is insensitive to errors, noise, and decoherence. Therefore, the scheme may provide helpful perspectives for accurate discrimination of chiral molecules.

We propose a protocol to realize atomic nonadiabatic holonomic quantum computation (NHQC) with two computational atoms and an auxiliary atom. Dynamics of the system is analyzed in the regime of Rydberg blockade, and robust laser pulses are designed via reverse engineering, so that quantum gates can be easily realized with hig h fidelities. In addition, we also study the evolution suffering from dissipation with a master equation. The result indicates that decays of atoms can be heralded by measuring the state of the auxiliary atom, and nearly perfect unitary evolution can be obtained if the auxiliary atom remains in its Rydberg state. Therefore, the protocol may be helpful to realize NHQC in a dissipative environment.

In this paper, we propose a scheme to generate nonclassical states in a nonlinear oscillator system, such as Fock states, squeezed coherent states, Schr\"odinger-cat states, etc. These nonclassical states are achieved by directly applying the classical field to the nonlinear oscillator, where the amplitude of the field is customized through a state-based Lyapunov control. For generating Fock states, there is no need to precisely control the operation time. As for the generation of other nonclassical states, we resort to a unitary transformation to design the control field, resulting in the requirement of a specific time. The Wigner function of the generated states shows the nonclassical property and shape that matches well with the target. Numerical simulations suggest that the scheme is robust against the field fluctuations and immune to variations in the initial state. In addition, the time-varying control field can be replaced by a square pulse based on the characteristics of the Lyapunov control, which may reduce the difficulty of the experiment.

A detailed chemical research of the soft coral Sinularia crassa collected from the South China Sea yielded a series of cembrane-type diterpenoids, including four new cembranoids, namely sinulacrassins A − C (1, (+)-2, (+)-4) and ent-xishaflavalin G ((+)-3), along with five known analogs ((-)-3, 5–8). Their structures were elucidated by detailed spectroscopic analysis, chemical methods, and the comparison with those literature data. The absolute configuration of 1 was established by time-dependent density functional theory electronic circular dichroism (TDDFT/ECD) calculation, and the absolute configuration of (+)-2 was determined using the modified Mosher's method. The bioassay results revealed that (+)-2 and 5 were novel α-glucosidase inhibitors with IC50 values of 10.65 ± 0.16 and 30.31 ± 1.22 μM, respectively. In addition, (+)-2 and 5 were nontoxic towards human normal hepatocyte (LO2) cells at 100 μM. The present results highlighted the unusual coexistence of α and β configurations of C-1 in cembranoids from soft coral in the Order Alcyonacea, and provided new chemotype for the development of α-glucosidase inhibitors used in anti-diabetes treatment.

Cysteine (Cys) is an important endogenous amino acid and plays critical physiological roles in living systems. Herein, an endoplasmic reticulum (ER)-targeting fluorescent probe (FER-Cys) was designed and prepared for imaging of Cys in living cells. The probe FER-Cys consists of a fluorescein framework as the fluorescent platform, acrylate group as the response site for the selective recognition of Cys, and ER-specific p-toluenesulfonamide fragment. After the response of probe FER-Cys to Cys, a turn-on fluorescence signal at 546 nm could be detected obviously. The probe FER-Cys further shows desirable selectivity to Cys. Finally, the probe FER-Cys was proven to selectively detect Cys in live cells and successfully image the changes of Cys level in the cell models of H2O2-induced redox imbalance.

A simple and rapid method employing non-suppressed ion chromatography with electrospray ionization tandem mass spectrometry has been developed for the direct determination of trace-level haloacetic acids (HAAs) in water samples. Using 70/30 (v/v) acetonitrile/1 M aqueous methylamine as the mobile phase, three IC columns – AS16, AS18 and AS24 from Thermo-Scientific – were tested, respectively, with the AS16 column exhibiting the best overall performance with respect to resolution and retention time. To assess the effects of mobile phase composition on retention time of HAAs, the AS16 column was further tested using (i) different proportions of acetonitrile to aqueous methylamine, (ii) different proportions of acetonitrile to aqueous solution at fixed methylamine concentrations, and (iii) different concentrations of methylamine at fixed proportions of acetonitrile to aqueous solution. With a low proportion of aqueous solution, van der Waals and/or hydrogen-bonding interactions appeared to play an important role in governing HAA retention, i.e., HAAs with relatively higher apparent logKow* caused by elevated solvent sspKa exhibited longer retention times; whereas with a high proportion of aqueous solution, ionic interactions appeared to dominate retention of HAAs, with the more polarizable HAAs exhibiting longer retention times. Using 70/30 (v/v) acetonitrile/1 M aqueous methylamine, the method detection limits were in the range of 0.090–0.216 μg/L for the 11 selected chloro-, bromo- and iodoacetic acids. Finally, this method was applied to monitor HAAs yields in laboratory chlorination experiments and to determine concentrations of HAAs in tap water and wastewater effluent samples.

Pyrodextrins were prepared from acidified waxy and normal tapioca starches (pH∼3) at 3 temperatures (130, 150 and 170 °C) and 3 times (1, 2 and 4 h) to determine their in vitro digestibility and molecular structure. Pyrodextrin from waxy tapioca starch produced at 170 °C/4 h had 5% higher total indigestible carbohydrate than pyrodextrin from normal tapioca starch (45.2 % and 40.4 %, respectively) as determined by a modified AOAC Method 2011.25. The low-molecular weight indigestible carbohydrate content at this condition was also higher for waxy tapioca starch than normal tapioca starch (40.6 % and 34.9 %, respectively). Gel permeation chromatography and nuclear magnetic resonance spectroscopy were used to study changes in molecular structure and correlate with digestibility of the pyrodextrins. Molecular size distribution indicated that waxy tapioca starch underwent thermal modification more readily than normal tapioca starch. Non α-1,4/α-1,6 glucosidic linkages were increased in the pyrodextrins with increasing in indigestible carbohydrate content.

In this study, a series of compounds with 1,2,4-oxadiazole core was designed and synthesized for the optimization of JC01, an anti-inflammatory hit identified from our in-house compound library using NF-κB pathway luciferase assay and NO production assay. All the synthetic compounds 1-29 have been screened for their anti-inflammatory effects by evaluating their inhibition against LPS-induced NO release, and compound 17 exhibited the highest activity. Western blotting and immunofluorescence analysis revealed that 17 prominently inhibited LPS-induced activation of NF-κB in RAW264.7 cells and blocked the phosphorylation of p65. Consistent with these results, it was found that 17 prevented the nuclear translocation of NF-κB induced by LPS. These data highlighted 17 as a promising anti-inflammatory agent by inhibiting NF-κB activity.

The objectives of this study were to study the extrusion of cross-linked waxy maize starches (CLWMS) with different cross-linking levels and their function as a secondary ingredient in extruded oat flour (OF) formulations. CLWMS (18 %) and OF (82 %) were hydrated to 20 % moisture content and subjected to twin-screw extrusion at the screw speed of 350 rpm. Low cross-linking level of CLWMS (0.05 % sodium trimetaphosphate/sodium tripolyphosphate) in OF formulation increased the void fraction and reduced the breaking strength of extrudates. The low cross-linked starch was more resistant to breakdown and had a higher pasting viscosity than the unmodified starch. Higher cross-linking levels of CLWMS restricted swelling of starch granule and increased the resistant starch level of OF formulation but had very poor structural and textural properties. Varying the level of cross-linking offers an alternative way to manipulate the structural, textural and nutritional properties of extrudates in snack and cereal applications.

The conformational properties of pyrodextrins from waxy maize starch were investigated by high performance size exclusion chromatography with multiple detectors, and the relationships (Mark-Houwink equations) between molecular weights and intrinsic viscosities of pyrodextrins in water were established. Pyrodextrin was prepared by adjusting waxy maize starch to pH 3 or 2, heating at 170 °C or 150 °C. As heating time increased from 0.5 to 4 h, the molecular size was decreased in the order of pH 2 and 150 °C > pH 3 and 170 °C > pH 3 and 150 °C. The measured exponent α values in Mark-Houwink equation indicated that the pyrodextrins prepared at pH 3, 170 °C and 150 °C only had one compact spherical conformation (α 0.27–0.31) during dextrinization, whereas the pyrodextrins prepared at pH 2 and 150 °C had a mixture of two shapes of molecules: compact sphere (α 0.26) and rigid coil (α 0.89) conformation.

Reducing the leakage from qubit levels to other levels is of importance for quantum computation. Here, we develop a feasible method to effectively suppress this leakage and perform universal quantum gates in a weakly nonlinear qubit. The method is to exploit periodical two-step modulation of single control parameters in a artificial large detuning regime. It works well, regardless of whether the strength of control parameter is known or not. In particular, qubit leakage can also be suppressed in a counterintuitive parameter regime, where the control field drives the transition of qubit levels with large detuning, but resonance transition with leakage level. The results demonstrate that this method is robust against parameter perturbations, and the deformation of square waves does not accumulate the error of qubit operations but affects the gate time. In addition, this method provides us with a viable approach to measure the control parameters.

UV/chlorine and chlorination processes have drawn great interests of water treatment utilities for oxidation and disinfection purposes. This work proposed a restricted chlorine-dosing strategy for UV/chlorine and post-chlorination under different pH and UV irradiation conditions by comprehensively assessing the oxidation of natural organic matter (NOM), formation of 9 haloacetic acids (HAA9) and bromate, and alteration of toxicity. During UV/chlorine with restricted chlorine doses, the oxidation of NOM chromophores (i.e., ΔUVA254) showed an apparent dependence on cumulative exposures of free available chlorine (CTFAC); Meanwhile, HAA9 formation was determined by CTFAC values and could be linearly correlated with ΔUVA254 irrespective of pH and UV irradiation wavelength. Irradiated by 254 nm LP-Hg lamp, the faster chlorine photolysis produced relatively higher steady-state concentrations of Cl• and HO• species but resulted in lower CTFAC. Reducing CTFAC values by operation parameters (pH, UV wavelength and irradiation fluence) could mitigate HAA9 formation during UV/chlorine at a specific chlorine dose. Additionally, high bromide concentration and acidic pH promoted more bromo-HAAs formation, and the presence of NOM significantly suppressed bromate formation. Analogous to ozonation, the UV/chlorine pre-oxidation could reduce the HAA9 formation potentials during post-chlorination at mildly alkaline pH. The photobacterium bioassay further demonstrated that although the UV/chlorine treatment might have increased the acute toxicity, the post-chlorination treatment could polish the acute toxicity to the level of chlorination alone. These results suggest that with the restricted chlorine-dosing strategy, the trade-off between oxidation/disinfection efficiency and DBPs formation can be controlled by monitoring CTFAC and ΔUVA254 values during UV/chlorine treatment.

Two different pearling degrees of wheat kernels (lightly-pearled: 14.4% and heavily-pearled: 38.9%) and un-pearled kernels were treated with ozone and evaluated for flour compositions and properties. Ozonation did not change main compositions and damaged starch content of three kernels' flours. Flour brightness of all three kernels was improved after ozone treatment. Ozonation enhanced the dough strength of the flours from un-pearled and pearled kernels and the effect elevated with increasing pearling degree. Ozone treatment increased the peak viscosity of flour and the level of increase in heavily-pearled kernels was greater than un-pearled and lightly-pearled. Ozonation resulted in an increase in the insoluble protein polymer content of heavily-pearled kernels' flour, but only had a slight effect on un-pearled lightly-pearled kernels. After ozone treatment, un-pearled and lightly-pearled kernels exhibited increases in molecular weight of starch, but heavily-pearled resulted in the opposite trend.

Drug discovery from traditional Chinese medicine (TCM) typically involves the extraction of active ingredients from natural products with high biological activity and function from the vast repertoire of traditional Chinese medicine. This strategy cannot fully exploit the vast resources of TCM. Known as the longevity mushroom, Ganoderma spp. has been used as medicine for thousands of years. Recent studies have demonstrated its anticancer activity. While most research on Ganoderma spp. has focused on their polysaccharides or small molecules as potential anticancer components, possible anticancer peptides (ACPs) or proteins have been neglected. In this study, genomic data mining approaches were used to discover potential ACPs from Ganoderma sinense. A search against known ACPs identified 477 proteins in the G. sinense proteome that possess putative ACP sequences and that thus may serve as parent proteins. After in silico digestion by trypsin, 34 G. sinense proteins were predicted to release putative ACPs (by the mACPpred program). A subsequent sequence similarity comparison against known ACPs identified 15 trypsin-digested fragments as possible ACPs, of which 3 sequences were identical to known ACPs. The results indicated that ACPs may be involved in the anticancer activity of G. sinense and that genomic mining approaches can be effective strategies for discovering active components in TCM resources. The accumulation of genomic and proteomic data will undoubtedly accelerate drug discovery from TCM resources.

In the paper, we propose a protocol for the one-step interconversions between the Greenberger-Horne-Zeilinger (GHZ) states and the $W$ states with deterministic success probabilities. The Rydberg interactions among three Rydberg atoms are utilized here to structure nonlocal operations for the interconversions. Additionally, we construct a Lewis-Riesenfeld invariant for a four-level system and afterwards use it to reversely design the Rabi frequencies of the effective Hamiltonian. The numerical simulations indicate that the protocol is robust against the spontaneous emission, the dephasing, the thermal noise, the systematic errors on Rabi frequencies, and the frequency mismatching. Therefore, the protocol may contribute to the research of the interconversions between entanglements.

We study the quantum phase transition in the Dicke model beyond the thermodynamic limit. With the Kibble–Zurek mechanism and adiabatic dynamics, we find that the residual energy is inversely proportional to the number of qubits, indicating that more qubits can obtain more energies from the oscillator as the number of qubits increases. Finally, we put forward a promising experiment device to realize this system.