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The identification of the water level time lag (WLTL) under the regulation processes is of great significance for environmental impact, flood control, and sediment transport of huge reservoirs. The traditional hydrodynamic method can calculate the flood inflow process and the water level change process along the river channel, but it is difficult to estimate the time difference of the reservoir water level fluctuation to the dispatching process. To quantitatively evaluate the reservoir regulation effect on the WLTL in the Three Gorges Reservoir (TGR), the daily water level data from 2011 to 2017 of five stations in the TGR are analyzed in this paper. The results revealed that there is a significant water level difference along the reservoir from April 1 to October 31. The gap between the end of the reservoir and the Three Gorges Dam (TGD) is the largest, reaching 23.67 m on July 2. The longer the distance from the TGD, the longer the time lag. Furthermore, the WLTL is also different at the four different operating periods of the reservoir in a year. During the low water level operation period and high water level operation period, the time lag is 3 days which is the greatest, while in the water level decline period and water level rise period, the time lag is within 2 days. HIGHLIGHTS Wavelet analysis is as an analysis tool for the time lag in the different hydrological process.; The water level in the whole reservoir showed an obvious difference from April to October.; The water level time lag in the reservoir area is related to the distance from the dam, the river channel landform, and the annual operation process of the TGR.; The time lag is not more than 3 days under the annual operation process.

In this work, we demonstrate that pure three-dimensional honeycomb-like porous carbons (3D-HPC) can be prepared by one-step simultaneous carbonization and activation of Ganoderma lucidum spores (GLS) with KOH active agent. Benefiting from the specific natural morphology of GLS and uniform activation process, the obtained 3D-HPC exhibits pure honeycomb-like hierarchical structures. The obtained 3D-HPC-900 shows the honeycomb-like structures and a high density of narrow mesopores, leading to a high accessible surface area. Combined with high specific surface area of 1995 m2 g−1 and oxygen/nitrogen doping, 3D-HPC-900 exhibits a high specific capacitance of 224 F g−1 at a current density of 0.25 A g−1, an ultrahigh capacitance retention of 75.9% even the current density increased by 80 times, and an excellent cycling stability with 100% capacitance retention after 50,000 cycles. More importantly, the maximum energy density can reach up to 75.7 W h kg−1 at the power density of 1750 W kg−1 in ionic liquid. Meanwhile, the experimental results clearly reveal the exclusive effects of mesopores on improving the rate performance in electrochemical capacitors. Therefore, the work provides a clear method on preparation of high-valued honeycomb-like structured carbon materials to enhance the rate capability of carbon-based electrochemical capacitors.

A synergistic inhibition study was carried out on an aluminium/copper galvanic coupling model in neutral aerated NaCl solution using scanning vibrating electrode technique (SVET). The approach allows the simulation of the local micro-galvanic cells of AA2024-T3 obtained from the potential difference between the intermetallic particles (IMPs) and the aluminium matrix. The inhibition effect of CeCl3 and 3-Amino-1,2,4-triazole-5-thiol (ATAT) was demonstrated by the reduction in the galvanic current density over Al and Cu surfaces. An improved inhibition from positive synergistic effect was revealed by the combination of the two inhibitors after 24 h of immersion, with the best inhibition recorded for Ce1.5ATAT3.5. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (ToF-SIMS) were used to characterize the Ce- and ATAT-based complex film formed and to illustrate the mechanism of inhibition.

In this paper, we present several new oscillation criteria for a second order nonlinear differential equation with mixed neutral terms of the form $$ \bigl(r(t) \bigl(z'(t)\bigr)^{\alpha }\bigr)'+q(t)x^{\beta } \bigl(\sigma (t)\bigr)=0,\quad t\geq t_{0}, $$(r(t)(z′(t))α)′+q(t)xβ(σ(t))=0,t≥t0, where $z(t)=x(t)+p_{1}(t)x(\tau (t))+p_{2}(t)x(\lambda (t))$z(t)=x(t)+p1(t)x(τ(t))+p2(t)x(λ(t)) and α, β are ratios of two positive odd integers. Our results improve and complement some well-known results which were published recently in the literature. Two examples are given to illustrate the efficiency of our results.

This work provides a new and simple method to improve the performance of polyamide reverse osmosis membrane, including selectivity properties and antifouling ability. Herein, quaternary ammonium groups have been immobilized on polyamide membrane surface by grafting and self-polymerization reaction of epoxy group in 2,3-epoxypropyl trimethyl ammonium chloride with tris(dimethylaminomethyl)phenol as curing catalyst. The surface properties of the modified membrane, such as surface charge, hydrophilicity and roughness have been characterized in detail and compared with virgin PA membrane. This novel modification method mainly achieves three advances in terms of membrane performance and fabricating technique. On one hand, the positively charged quaternary ammonium group immobilized on membrane surface can prevent cationic surfactant absorbing to improve fouling-resistance, due to the electric repulsion effect. On the other hand, self-polymerization reaction based on epoxy group occurred on polyamide surface can fill up the aggregate pore or reduce the pore size in polyamide, resulting in the increase of salt rejection. More importantly, the membrane modification process is very simple and efficient, which adapts to fabricate RO membrane with high performance on industrial production line completely.

The development and adoption of agriculture has been investigated for decades, and remains a central topic within archaeology. However, most previous studies focus on the crop’s domestication centers, leading to gaps in knowledge, particularly in transitional zones between these centers. This paper reviews published archaeobotanical evidence and historical documents to reconstruct the trajectory of agricultural systems in Holocene Jiangsu Province. Comparing these new results to paleoclimate information, historical documents, and archaeological data enables us to better understand the underlying influences of past agricultural development. Our results indicate that a warm and wet climate may have promoted ancient peoples to first settle in Jiangsu between 8,500 and 6,000 BP and adopt rice farming. The continuous warm and wet climate may have facilitated the rapid development and expansion of rice agriculture, ultimately contributing to large-scale human settlement in 6,000–4,000 BP in Jiangsu Province. Between 4,000 and 2,300 BP during a cooler and drier climate millet agriculture diffused southward, facilitating a mixed rice and millet agricultural system. This mixed farming supported a continuesd widespread settlement and population growth in Jiangsu. After 2,300 BP, political instability in north China resulted in further southeastward migration, advanced planting technology was brought about to south China, facilitating highly developed agricultural systems and rapid population expansion in Jiangsu. Population growth led to the establishment of Jiangnan as the regional economic center, where people chose high-yielding rice and wheat rather than millet.

Novel etched iron oxide mediated synthesis of 3D tremella-like mesoporous Fe/N co-doped graphene composite was investigated. Through a synergistic mediation of acid etched Fe2O3 particles and released Fe3+, the nanoflakes of graphene oxide were transformed to Fe-doped 3D tremella-like mesoporous structure in hydrothermal condition. With high temperature treatment using melamine as the nitrogen source, the novel 3D tremella-like mesoporous Fe/N co-doped graphene composite for platinum-free counter electrode of the sensitized solar cell was synthesized. The samples had good pore size distribution and large specific surface area, which could be considered as an advantage for the permeation of electrolyte and beneficial to reduce the mass transfer resistance and promote the charge transfer. Significantly, the formed Fe-NX species bonding on the surface of graphene had sturdy covalent structure with high catalytic activity, which contributed to the excellent electrochemical properties and counter-electrode performance of dye-sensitized solar cell. Consequently, the photoelectric conversion efficiency reached 6.52%, which exceeded 5.87% of Pt and 3.49% of reduced graphene oxide electrodes.

A new corrosion inhibitor, cerium malate, was synthesized. Its inhibiting behaviour on coupled Al2Cu-Al2CuMg-Al, Al2CuMg-Al and Al2Cu-Al was studied. Cerium malate is effective in corrosion inhibition of the three coupled systems. The inhibition mechanism of cerium malate on pitting corrosion of Al2CuMg and Al2Cu phases in AA 2024-T3 was analyzed by scanning vibrating electrode technique (SVET), atomic force microscopy (AFM) and scanning kelvin probe force microscopy (SKPFM). The results indicate that cerium malate has good inhibiting effect on AA 2024-T3.

Cerium malate (CeMal) was tested as a corrosion inhibitor for AA2024-T3 in this work. Corrosion inhibition on bare AA2024-T3 indicated that the inhibiting effect was a result of the synergistic effect of cerium cations and maleic anions. The corrosion of AA2024-T3 was stagnated by greatly reducing the corrosion current when CeMal was present in NaCl solutions. CeMal was adsorbed on the surface of AA2024-T3 forming a protective film in the initial stage. Then, cerium cations transformed to cerium oxide/hydroxides, precipitating on the cathode sites to inhibit the further corrosion. The electrochemical impedance spectra results of the sol–gel coatings proved that CeMal was an effective corrosion inhibitor in the sol–gel coatings to provide corrosion protection for AA2024-T3.

(Ho,Sb)-modified (Bi0.5Na0.5)0.945Ba0.065TiO3 (BNBT6.5) multifunctional ferroelectric ceramics were fabricated by a conventional solid-state reaction method. Results showed that (Ho, Sb)-modified BNBT6.5 materials exhibited a bright green photoluminescence while simultaneously obtaining a large electric-field-induced strain of 0.37% (80 kV/cm) in samples with x = 0.50% due to the appearance of an ergodic relaxor phase at zero field. Under the electric field, the ergodic relaxor phase could reversibly transform to ferroelectric phase. As a result, the strain is very resistant to field cycling due to the reversible field-induced phase transition between the ergodic relaxor and ferroelectric phase, giving the materials attractive for its good fatigue resistance. Besides the excellent strain properties, (Ho, Sb)-modified BNBT6.5 host exhibits a bright photoluminescence with a strong green emission located at around 549 nm owing to the 5S2→5I8 transition under the 451 nm light excitation at room temperature. As a multifunctional material, (Ho,Sb)-modified BNBT6.5 ferroelectric materials showed great potential in optical-electro integration and coupling device applications.

A series of thin-film composite membranes based on polyurea has been fabricated by interfacial polymerization with branched polyethyleneimine and piperazine in the aqueous phase, and multi-isocyanate in the organic phase on porous polyethersulfone support for extreme pH nanofiltration. It is found that 1,4-phenylene diisocyanate and toluene diisocyanate are more suitable to react with multi-amine to form the dense crosslinking layer, thereby achieving improved permeation and separation properties. By optimizing the ratio of polyethyleneimine to piperazine in the aqueous phase and 1,4-phenylene diisocyanate content in the organic phase, the best performance membrane with a MgSO4 rejection higher than 97.0% has been obtained. The surface properties of the polyurea-based membranes, such as surface charge, hydrophilicity, roughness, and morphology structure have been characterized in detail. After exposure to 20% (wt/v) HCl, 20% (wt/v) H2SO4, as well as 20% (wt/v) NaOH aqueous solution for one year, PEI-0.4/PDI-0.25 membrane can still retain MgSO4 rejection higher than 90% at neutral pH testing condition, with more than a two-fold increase of water flux, due to the swelling of the polyurea separation layer. The relationship between the molecular structure of polyurea and acid/alkali stability of membrane is also investigated. More importantly, the optimal polyurea-based nanofiltration membrane exhibits comparable acid/alkali stability to commercial MPS-34 membrane produced by Koch industries, displaying a broad field of application with good prospects.

Food safety has aroused increasing public concerns because it is closely related to human health. As a common pollutant, mercury ions (Hg2+) can cause an enormous menace to human health even at very low fouling level. Herein, we designed a three-dimensional reduced graphene oxide (rGO) doped by silver nanoparticles (Ag-rGO), which could be employed as an effective sensing interface to electrochemically detect Hg2+. By characterization with scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), we confirmed that the Ag-rGO composites had multiple fold structures. After incubation with Hg2+, an obvious electrochemical signal enhancement was observed, which could be applied to detect the low level of Hg2+. The sensor based on Ag-rGO exhibited a low detection limit of 0.0049 μg/L of Hg2+ due to its multiple folds structure providing a large electrochemical active area and facilitating the electron transfer. Significantly, this proposed sensor was successfully used to evaluate the amount of Hg2+ in fish and human blood samples with acceptable results. This sensing strategy showed excellent performance for Hg2+ detection in food and clinical-related systems, which is of great significance for safeguarding food safety and human health.

The inefficiency of charge separation is the major practically limited factor towards high hydrogen evolution reaction (HER) of photocatalysts. Therefore, design and construction of efficient photocatalysts system with efficient charge transfer path is urgently necessary for HER. Herein, we report an effective strategy to construct Pt–MoSe2/g-C3N4 heterostructure through integrating facile solvothermal technique and solution-phase hybridization method. The synthesized ternary Pt–MoSe2/g-C3N4 heterostructures exhibit greatly enhanced photocatalytic hydrogen production than bare g-C3N4 and Pt/g-C3N4 catalyst. The enhancement factor is directly correlated with strong photosynergistic effect of charge-carrier generation and separation path coupling heterojunction sensitization on MoSe2/g-C3N4 with Pt nanoparticle. Moreover, the mechanism of enhanced catalytic activity is fully studied by electrochemical characterizations and photocurrent analysis.

The corrosion behavior of cupronickel alloy immersed in the simulated seawater in or without the presence of sulfate-reducing bacteria (SRB) was studied. The results of scanning electronic microscopy and electrochemical impedance spectra reveal that corrosion of the sample immersed in the simulated seawater with SRB was more serious than that immersed in the simulated seawater without SRB. The atomic force microscopy images show that after immersion for 15 days, the surface roughness of the sample in the simulated seawater with SRB was higher than that of the sample in the simulated seawater without SRB. The analysis of confocal laser scanning microscopy indicates that the average depth of the pits on the surface of the sample in the simulated seawater with SRB was almost twice deeper than that of the sample in the simulated seawater without SRB.

The solubility of terbinafine hydrochloride in four pure solvents, including methanol, ethanol, n -propanol and ethyl acetate and their binary solvent mixtures, including (methanol + ethyl acetate), (ethanol + ethyl acetate) and ( n -propanol + ethyl acetate) performed at different mass fractions of methanol, ethanol or n -propanol ranging from 0.1 to 0.9, was determined by using isothermal saturation method with temperatures ranging from (278.15 to 313.15) K. The descending order of the mole fraction solubility in pure solvents was as follow: methanol > ethanol > n -propanol > ethyl acetate, and for the three mixture with given initial composition, the solubility of terbinafine hydrochloride increased with increasing temperature and mass fraction of alcohol for the three systems including (methanol + ethyl acetate), (ethanol + ethyl acetate) and ( n -propanol + ethyl acetate). At the same mass fraction of methanol, ethanol or n -propanol and temperature, the solubility of terbinafine hydrochloride was greater in (methanol + ethyl acetate) than in the other mixed solvents. The maximum mole fraction solubility of terbinafine hydrochloride was observed in methanol (6.297 × 10 − 2 at 313.15 K), followed by that in ethanol (3.785 × 10 − 2 at 313.15 K), n- propanol (3.007 × 10 − 2 at 313.15 K) and ethyl acetate (1.497 × 10 − 2 at 313.15 K)·The obtained solubility data were correlated with Jouyban-Acree model, van't Hoff-Jouyban-Acree model, modified Apelblat-Jouyban-Acree model and CNIBS/R-K model. The correlation showed good agreement with experimental results, the largest values of relative average deviations ( RAD ) and the root-mean-square deviations ( RMSD ) between the experimental and calculated solubility were 4.32 × 10 − 2 and 15.28 × 10 − 4 , respectively. On the basis of the obtained solubility, the standard enthalpy of solution ( ΔH sol o ), the standard Gibbs energy ( ΔG sol o ) of solution and the standard entropy of solution ( ΔS sol o ) of terbinafine hydrochloride dissolved in pure and mixed solvents were obtained by the famous van't Hoff calculations. Thermodynamic treatment of solubility data of terbinafine hydrochloride in these pure and mixed solvents by “Apparent thermodynamic analysis” indicated that the dissolution is an endothermic and entropy-driven process. The experimental solubility and the models in this study could be helpful in purifying the crude terbinafine hydrochloride.

In the present work, the sub-micrometer containers were prepared using mesoporous silica particles (SBA-15) with parallel channels as reservoir and 8-hydroxyquinoline as corrosion inhibitor. Layer-by-layer assembling was used to construct a shell of polyelectrolytes around the silica particles. Release of 8-hydroxyquinoline from sub-micrometer containers was studied in response to acidic or alkaline pH values. The results of electrochemical impedance spectroscopy (EIS) show the improvement of corrosion resistance of epoxy coatings containing sub-micrometer containers. Self-healing ability of the epoxy coatings was provided by sub-micrometer containers, as evidenced by the results of scanning vibrating electrode technique (SVET).

We have developed a facile and efficient Fe-catalyzed method for fabrication of porous carbons spheres with high graphitization degree (GNPCs) using glucose as carbon precursor at relatively low carbonization temperature. GNPCs not only have relatively large accessible ion surface area to accommodate greater capacity but also high graphitization degree to accelerate ion diffusion. As a typical application, we demonstrate that GNPCs exhibit excellent electrochemical performance for use in supercapacitors, with high specific capacity of 150.6 F g−1 at current density of 1 A g−1 and good rate capability and superior cycling stability over 10,000 cycles, confirming their potential application for energy storage. Moreover, it is believed that this method offers a new strategy for synthesis of porous carbons with high graphitization degree.

A correction method for obtaining the phase modulation curves of liquid crystal spatial light modulator (LCSLM) systems under oblique incidence is proposed. Considering the reflection and refraction of the interface, the influence of oblique incidence on the LCSLM phase modulation was simulated and analyzed by solving the extended Jones matrix. The polarization interference principle was applied to construct a phase modulation system, the phase modulation was measured at different incident angles, and the measured data were subjected to Fourier fitting. The phase modulation curve was corrected to a straight line using the inverse interpolation method, and the lookup table (LUT) for the gray level and phase was then generated through the line coordinates. The measured results revealed that a larger angle of oblique incidence led to a smaller range of phase modulation. For LCSLM to function over a range from 0 to 2π, the oblique incidence angle should be less than 45°. Experimental results using 25° as an example confirmed the validity of the LUT. The correlation coefficient R between the phase modulation curve and the ideal linear curve was 0.9893, and the root-mean-square error was 0.1888. At incident angles from 0° to 45°, the linearity of the corrected LUT was as good as that of the LUT for vertical incidence, thereby laying the foundation for high-precision beam pointing control.

The study of aviation safety report in the aviation industry usually relies on manually labeled data sets, and then classifies and models related problems, which have become insufficient in the face of increasingly rapid report data. Therefore, in this paper, we propose an unsupervised machine learning algorithm architecture to explore topics (rather than categories) for optimizing aviation safety report text mining research, and further conducts preliminary experiments with real data from the Aviation Safety Report System (ASRS). The experimental results show that compared with traditional classification modeling, this scheme can identify latent topics with higher interpretability, and the training data does not rely on manual labeling, which can greatly improve the efficiency and pertinence of aviation safety report research.

In this work, urea-formaldehyde (UF) microcapsules loaded with tung oil were prepared by in-situ polymerization. The mean diameter of the obtained microcapsules was 8.5 μm. The self-healing coating was prepared by the addition of 5 wt.% microcapsules into an epoxy matrix and then painted on the AA2024 substrate. The effect on the coating properties after the incorporation of microcapsules was investigated by adhesion tests and electrochemical impedance spectroscopy (EIS). It is found that 5 wt.% microcapsules in coating formulations did not impart a significant negative effect on coating properties. SEM and EIS tests were used to evaluate the self-healing effect. According to the fitting results of the EIS data on the scratched samples, the new film that formed by the polymerization of tung oil at the scratched area in the self-healing coating displays a resistance value of more than 106 Ω·cm2, which is much higher than 103 Ω·cm2 of the oxide layer in the neat epoxy coating. The neutral salt spray tests also confirm the good anti-corrosion performance of the self-healing coating.

Silica nanoparticles are used as additives to organic coatings to modify their properties. The interface of inorganic nanoparticles with an organic matrix can be a preferred location for accumulation of water. Surface treatment of nanoparticles with 3-glycidoxypropyltrimethylsilane (silane) is one way to reduce the water accumulation. In this work, using atomistic simulations (MD), we studied the effects of silane treatment on accumulation of water at the interface of nanoparticles. Three different epoxy phases and two methods of deposition of water were simulated. Water molecules were studied at two locations: (i) the interface of nanoparticles, and (ii) in the matrix of coatings. Additionally, the changes in the organic matrix due to surface treatment of nanoparticles were studied. The simulations show how silane treatment affects the interactions of water with nanoparticles in different epoxies, and also how silane treatment reduces the water accumulation in an organic matrix with nanoparticles.

The solubility of econazole nitrate (racemic mixture) in organic solvents is of clear importance for the design of separation processes and further theoretical studies. In this work, the solubilities of econazole nitrate in methanol, ethanol, n -butanol, isopropanol, ethyl acetate, 2-butanone, 3-methyl-1-butanol, acetonitrile, 1,4-dioxane, N , N -dimethylformamide (DMF), 1-methyl-2-pyrrolidinone (NMP) and acetone were determined at the temperatures from 278.15 K to 318.15 K under atmosphere pressure ( p = 101.2 kPa) by high-performance liquid chromatography (HPLC). It was found that the econazole nitrate solubilities in mole fraction in selected solvents increased with the increase in temperature. At a given temperature, they obeyed the following order from high to low in different solvents: NMP > DMF > methanol > 2-butanone > acetone > (3-methyl-1-butanol, ethanol) > acetonitrile > n -butanol > isopropanol > 1,4-dioxane > ethyl acetate. The experimental solubility data were correlated with the modified Apelblat equation and the Buchowski–Ksiązczak λh equation. The calculated solubilities using the modified Apelblat solubility model were in better agreement with the experimental values. The largest percentage of average relative deviation was 1.53% for solubility of econazole nitrate in isopropanol calculated with the λh equation, and the maximum value of root-mean-square deviation was 2.11 × 10 −4 . Based on the modified Apelblat equation, the apparent dissolution enthalpies of econazole nitrate in twelve pure solvent were derived. The results indicate that the dissolution of econazole nitrate in all studied cases is endothermic process.

The solubility of 2,4′-dihydroxydiphenyl sulfone in methanol, ethanol, acetone, acetonitrile, ethyl acetate, 1,4-dioxane, n-butanol, isopropanol and 2-butanone was determined at temperatures from (278.15 to 313.15) K under 101.2 kPa by using the high-performance liquid chromatography (HPLC). With the increase in temperature, the solubility of 2,4′-dihydroxydiphenyl sulfone in these solvents increased. Generally, the mass fraction solubility followed the sequence from high to low in different solvents except for 1,4-dioxane: acetone > methanol > (2-butanone, ethanol) > isopropanol > n-butanol > ethyl acetate > acetonitrile. The solubility of 2,4′-dihydroxydiphenyl sulfone in 1,4-dioxane showed the strongest positive dependency on temperature. The measured solubility of 2,4′-dihydroxydiphenyl sulfone were correlated by using four thermodynamic models, which corresponded to the modified Apelblat equation, λh equation, Wilson model and NRTL model. The largest values of RMSD and RAD were 9.52 × 10−4 and 1.54%, respectively. By comparing the four models, the computed solubility using the modified Apelblat equation provided better agreement with the experimental values than those using the other three models. On the whole, the four models were all acceptable for describing the solubility of 2,4′-dihydroxydiphenyl sulfone in the selected solvents. In addition, the standard molar dissolution enthalpy and excess enthalpy of solution of 2,4′-dihydroxydiphenyl sulfone in the solvents were evaluated. The dissolution process of 2,4′-dihydroxydiphenyl sulfone in the selected solvents was endothermic. The study on the solubility of 2,4′-dihydroxydiphenyl sulfone in the selected solvents and solution properties can provide fundamental data in the separating process of 2,4′-dihydroxydiphenyl sulfone from its isomeric mixtures.

In the present study, the solubility of 4,4′-dihydroxydiphenyl sulfone in mixed solvents of (acetone + methanol), (ethyl acetate + methanol), (acetonitrile + methanol), and (acetone + methanol) were determined experimentally by using the isothermal dissolution equilibrium method within the temperature range from (278.15 to 313.15) K under atmosphere pressure. The solubility increased with increasing temperature in the binary solvent mixtures at constant solvent composition. At constant temperature and solvent composition, the dissolving capacity of 4,4′-dihydroxydiphenyl sulfone in the four binary solvent mixtures ranked as (acetone + ethanol) > (acetone + methanol) > (ethyl acetate + methanol) > (acetonitrile + methanol). The obtained solubility data were correlated by employing the Jouyban–Acree model, modified Apelblat–Jouyban–Acree model, Ma model and Sun model. The four models were proven to give good representation of the experimental solubility data. The largest value of relative average deviations...

A new and convenient procedure is developed for the preparation of N-sulfonylbenzotriazoles from sodium sulfinates and benzotriazoles using molecular iodine as catalyst via the SN bond formation reaction. This catalytic radical sulfonylation proceeds efficiently in air at room temperature under neutral conditions, and in short reaction time, to afford the corresponding N-sulfonylbenzotriazoles in good yields, thus extending the catalytic application of molecular iodine in organic synthesis.

This article reported an eight steps formal total synthesis of (−)-kainic acid in 16% overall yield from an enantiopure starting material. The key transformations include an efficient tandem N-allylation/SN2′ reaction to construct the 2,3-trans-3,4-cis tri-substituted pyrrolidine and a HgCl2-promoted methanolysis of 1,4-benzodithia-fulvene to furnish the ester group.

The solubility of 3-chloro -N -phenylphthalimide in binary mixed solvents of (acetone + methanol, ethyl acetate + methanol and 1,4-dioxane + methanol) were determined experimentally by using the isothermal dissolution equilibrium method within the temperature range from (288.15 to 323.15) K under atmosphere pressure. For the binary systems of (acetone + methanol) and (1,4-dioxane + methanol), the solubility of 3-chloro -N -phenylphthalimide increased with increasing temperature and mass fraction of acetone or 1,4-dioxane; and for the (ethyl acetate + methanol) system, at a given composition of ethyl acetate, the solubility of 3-chloro -N -phenylphthalimide increased with an increase in temperature; nevertheless at the same temperature, they increased at first and then decreased with increasing mass fraction of 1,4-dioxane. At the same temperature and mass fraction of acetone, ethyl acetate or 1,4-dioxane, the solubility of 3-chloro -N -phenylphthalimide was greater in (1,4-dioxane + methanol) than in the other two mixed solvents. The solubility values were correlated by employing the Jouyban–Acree model, van’t Hoff–Jouyban–Acree model, Apelblat–Jouyban–Acree model, Ma model, and Sun model. On the whole, the Ma model and Sun model were proven to provide good representation of the experimental solubility results. Furthermore, the dissolution enthalpies of the dissolution process were calculated. The dissolution process of 3-chloro -N -phenylphthalimide in these mixed solvents is endothermic. The experimental solubility and the models in this study could be helpful in purifying 3-chloro- N -phenylphthalimide.

The solubilities of 1,5-dinitro-naphthalen in eight organic solvents (acetonitrile, ethanol, trichloromethane, 1-propanol, acetone, toluene, ethyl acetate and ethylbenzene) were determined experimentally by using a static equilibrium method at temperatures ranging from (273.15 to 313.15) K under atmosphere pressure (101.2 kPa). They all increased non-linearly with the increase in temperature for a certain solvent. Generally, the order of the solubility of 1,5-dinitro-naphthalen from high to low in different organic solvents was: trichloromethane > toluene > (ethyl acetate, acetone) > ethylbenzene > acetonitrile > 1-propanol > ethanol. The maximum solubility was 4.508 × 10− 3 in mole fraction. As the temperature decreased from 313 K to 273 K, the maximum solubility decreased from 4.508 × 10− 3 to 1.573 × 10− 4. The measured solubility data of 1,5-dinitro-naphthalen in the studied solvents were correlated with four solubility models, which corresponded to the modified Apelblat equation, λh equation, Wilson model and NRTL model. The calculated solubilities agreed better with the experimental values by using the modified Apelblat equation than the other three models. The relative average deviations obtained via the four models were all

We have demonstrated an acousto-optical cavity dumping Tm:YAG ceramic laser at a wavelength of 2012.6 nm. The pulses were coupled out of the cavity by the lateral surface when radio frequency was added into the acousto-optical modulator. The minimum pulse width of the cavity dumped Tm:YAG ceramic laser is 31 ns, corresponded with an output power of 180 mW and a repetition rate of 200 kHz. In addition, the unsmooth pulse shape of the cavity dumped Tm:YAG ceramic laser was numerically calculated.

In this paper, we consider an upper bound for the maximum number of limit cycles bifurcating from the periodic solutions of x ¨ + x = 0 under piecewise smooth perturbation. By using the first order average method, we prove that the maximum number is at most n and n can be reached.

In this work, we used atomistic level simulations to study water molecules confined between an epoxy layer and alumina substrate. Water is responsible for many complex reactions at the interface of substrate, which makes understanding characteristic properties of water at this particular confinement essential. Three different confinement sizes were selected. The substrate is hydroxylated gamma alumina and the organic coating layer is constructed with epoxy molecules. Different properties such as density, mobility and displacement, inter-molecular structures, power spectra, and hydrogen bond energy of water molecules were obtained. The results are studied in connection with the size of confinement. It is shown that the properties of water in this type of confinement are different from the bulk water and as the size of confinement decreases, some of the unique behaviors of water molecules are revealed.

A facile surface modification method has been developed for improving the antifouling property of TFC membranes by immobilizing poly(ethylene glycol) (PEG) onto polyamide (PA) surface. PEG has been chelated and immobilized onto PA surface by ion-dipole interaction between ether oxygen atoms in PEG backbone and –COONa in PA layer. The resulting TFC membranes were characterized by ATR-FTIR, XPS, SEM, AFM, WLI, zeta potential as well as static contact angle. The changes in chemical composition and morphology of the membrane surface indicate the successful modification process. The permeation property of the PEG modified TFC membranes dependence on PEG concentration, treatment temperature and time has been investigated thoroughly. The optimized PEG modified membrane shows a NaCl rejection of 99.04%, higher than that (97.79%) of the virgin membrane. More importantly, PEG modified membrane exhibits much more improved organic fouling-resistance ability than control sample. Typically, after BSA fouling for 12 h, PEG modified membrane loses about 19% of the initial flux, much lower than that of the virgin PA membrane (40%). Furthermore, the flux recovery of the PEG modified membrane reaches about 95% after cleaning, much higher than that of the virgin PA membrane (79%). Therefore, this simple, rapid, environment-friendly and cost-effective modification approach will provide a method for mitigating the long-term fouling of reverse osmosis membrane.

Recrystallization behavior and the final crystallite orientation of biaxially oriented polyethylene (BOPE) film from different melted states have been studied by using differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD), respectively. WAXD result shows that two kinds of crystallites (1 and 2) with different orientations are aligned around the transverse direction (TD) of the film plane. When BOPE film is annealed in the temperature range of 110~125 °C, the residual crystallites 1 are still aligned along the TD, while the residual crystallites 2 are gradually rotated and aligned along the machine direction (MD). Recrystallization of BOPE film from the partially melted states is enhanced and the maximum crystallization peak shifts to higher temperature by 7 °C. The newly formed crystallites after recrystallization are aligned along the TD and MD, respectively. When annealing temperature attains to 128 °C, a trace amount of residual crystallites 1 persists along the TD. The newly formed crystallites after recrystallization are also aligned the TD. When the storing temperature range is in 130–150 °C, the melt memory effect occurs in BOPE film, and it influences crystallization kinetics and the crystallite orientation.

As for the stability control problem for rotary inverted pendulum, the two closed-loop fractional order PID control scheme is used to control the pendulum. First, the mathematical model of rotary inverted pendulum is established according to the Euler-Lagrange equation. Then, a fractional order PID controller is designed based on the Bode ideal transfer function. Finally, the fractional order PID (FOPID) controller, fractional PD (FOPD) controller and integer order PD (IOPD) controller are applied to the rotary inverted pendulum system which based on the Quanser company loop simulation experiment platform. The results show that the FOPID controller is better than the FOPD and IOPD controller in stabilizing the system and the angle of the pendulum is closest to the stable equilibrium point.

In order to extract the weak signal in the long distance pulsed laser ranging, this paper uses the AD sampling rate of 1GHZ sampling rate to digitally collect the echo signal. According to the non — correlation of the noise, using the multi — pulse coherent superposition method, the useful signal strength is And then the signal-to-noise ratio can be improved. At the same time, the method of wavelet singular value filtering is used to process the accumulated signal to improve the measurement precision and realize the control system by FPGA and other hardware. In this paper, the measurement targets at different distances are tested, and the results show that the method can greatly improve the measurement accuracy of the laser ranging system.

The molecular dynamics (MD) method can be a reliable tool for studying of organic coating/metallic substrate systems, however its accuracy is limited to the force field governing the dynamics of systems. These systems can be divided into three parts: (i) organic phase, (ii) substrate, (iii) interface between the organic phase and substrate. In this work, three recent ReaxFF descriptions were selected. A set of complex experimental data and density functional calculations was selected as the reference point. The density and structural analysis of a wide range of crystalline organic compounds were studied. The density, structural analysis, and self-diffusion constant of water at room temperature were obtained. The glass transition temperature of three different cross-linked epoxy were obtained and compared with the reported experimental results. The interaction energies of different configurations of epoxy and water over an alumina substrate were studied. Additionally, the reaction of water with aluminum was studied. The accuracy of these ReaxFF descriptions in reproducing the reference data was assessed. The results show there is a single ReaxFF description for accurate simulation of C/H/N/O/Al systems, which enables atomistic simulations of complex epoxy coatings/aluminum substrates systems.

New insights on the effect of nature and number of polyelectrolyte (PE) shells on active anticorrosion potential of microcontainers (MCs) applied as pH-sensitive reservoirs in coatings for the protection of AA2024-T3 is reported. Mesoporous silica particles (MSP) were loaded with benzotriazole (BTA) and shelled with different polyelectrolyte multilayers (PEM), demonstrating pH sensitivity. Weak-weak polyelectrolyte (W-W PE) shells allow immediate release of inhibitor, but weak-strong polyelectrolyte (W-S PE) shells encourage slower, more controlled and prolonged release, as revealed by release profiles of BTA from microcontainers. Active anticorrosion protection characterizations of the coatings doped with microcontainers were carried out by electrochemical techniques (EIS, SVET) and salt spray tests. Results reveal dependence of active properties of coatings on the nature and number of polyelectrolyte multilayers of microcontainers. We anticipate that proper choice of PEMs on smart containers can aid controlled functionalization of active feedback systems.

Highly dispersed nanometer BiVO4 on attapulgite (ATP) as hybrid inhibitor pigment was prepared using chemical bath deposition. Microscopy analysis shows that nanometer BiVO4 particles uniformly grow on attapulgite. The immersion and polarization tests show that ATP-BiVO4 inhibits corrosion of aluminium alloy 2024-T3. The EIS results indicate that the coating resistance of ATP-BiVO4 containing epoxy coating is approximately two orders of magnitude higher than that of the epoxy coating containing only attapulgite. The enhanced corrosion protection ability of ATP-BiVO4 containing epoxy coating can be ascribed to the combination of the barrier effect of ATP-BiVO4 and the inhibition effect of the released vanadate at the coating/substrate interface. The deposition of BiVO4 with inhibition ability on fillers provides a new way to develop hybrid inhibitor pigment.

Using organic coatings with high barrier property in combination with active corrosion protection can improve corrosion protection of aluminum alloys. In this work, 3-Amino-1,2,4-triazole-5-thiol (ATAT) was used as organic inhibitor in developing anticorrosion coatings for AA2024-T3. The delivery of ATAT was achieved by using smart microcontainers with ATAT that respond to pH change caused by corrosion reaction at the coating-substrate interface. The developed coatings with low concentration of smart microcontainers showed a slight reduction of barrier properties, but gained active corrosion protection capability. The resistance of the coatings reduced the rate of penetration of corrosive species and the active corrosion protection stopped the damaging reactions at the coating-substrate interface. The active corrosion protection is also evident in the case of coatings with mechanical damages, when the barrier property of coatings is compromised. Waterborne coatings with smart microcontainers for delivery of ATAT exhibited enhanced performance for corrosion protection of AA2024-T3.

Synthesis of transparent polypropylene (PP) copolymers with low migration of soluble contents is of great significance due to their extensive use in food and medicine industries. We present here a systematical study on the relationship between the microstructure of PP copolymers and their soluble properties using a solvent gradient fractionation (SGF) method. Two sets of poly(propylene-co-1-butene) (PPBu) and poly(propylene-co-ethylene) (PPEt) samples with comparable comonomer content and molecular weight were first fractionated and characterized by 13C NMR, GPC, DSC, and WAXD. It was found that PPBu contained much less room temperature soluble fraction than PPEt because of the incorporation of 1-butene into higher molecular weight fraction than that of ethylene. The melting temperature of PPBu was found higher than that of PPEt with similar comonomer content because of the isomorphism phenomenon demonstrated by the expansion of the unit cell. The findings in this study suggest that tuning the two structure-related factors, namely, comonomer distribution homogeneity and isomorphism phenomenon, plays a key role to maintain low soluble contents of transparent PP copolymers.

In recent years, with the development of modern optics and laser technology, modern industry for optical surface roughness measurement precision of the increasingly high demand, real-time, fast and precise measurement of surface roughness has become constant subject of optical components in processing and test. In this paper, the current method of measuring the surface roughness of optical components were described in detail, including light scattering method, interferometric method, speckle method, and optical stylus method. Besides, the principles and characteristics of different methods were introduced respectively.

Thin-film-composite (TFC) polyamide membranes with flux-enhancement were prepared by the interfacial polymerization of m-phenylenediamine with trimesoyl chloride on porous polysulfone support. The addition of 1,3-propanesultone (PS) in the organic phase is used to influence the interfacial polymerization process and the morphology of polyamide layer to improve water flux. FTIR, 1H NMR and UV spectra were performed to investigate the effect of PS on interfacial polymerization process. In order to study the forming mechanism of TFC membrane, the resulting TFC membranes were characterized by SEM, AFM, ATR-FTIR, XPS, as well as static contact angle. In comparison with conventional polyamide membrane, the TFC membranes fabricated with PS as the additive exhibit much more improved water flux without NaCl rejection decreasing. Notably, the optimal TFC membrane with 0.04% (wt/v) PS as the additive in organic phase shows the best performance with a NaCl rejection of 99.39% and a water flux of 48.57 L m−2 h−1 at 1.55 MPa, which has increased 41% compared to the value of the conventional TFC membrane.

A substrate stereocontrolled synthesis of the BCD tricyclic ring system of densanins A and B has been developed. The key transformations include the assembling of ring B via an unprecedented tandem N-allylation/SN2′ reaction and the construction of ring C via gold-catalyzed alkenylation of terminal alkyne and pyrrole.

Combined Nearly Ideal Binary Solvent/Redlich-Kister (CNIBS/R-K) equations and van't Hoff-Jouyban-Acree model reported by Liu and coworkers [J. Mol. Liq. 220 (2016) 354–363] for calculating the solubility of meldrum's adduct in ethyl acetate plus (acetonitrile, ethanol, hexane) binary solvent mixtures at various temperatures. The authors of cited reference erroneously curve-fit the solubility data with multiplying the solubility value by ten times in the case of published equation coefficients for the CNIBS/R-K model. In addition, the authors of cited reference applied original van't Hoff-Jouyban-Acree model to predict meldrum's adduct solubility in mixed solvents at different temperatures, but that overlooked the fact that they did not measure the solubility data for meldrum's adduct in neat solvents. Furthermore, in determining the numerical values of the equation coefficients, no pure solvent solubility data were included in the regression analyses.

Using potassium iodide as a catalyst and m-chloroperbenzoic acid as an oxidant, an efficient catalytic procedure has been developed for the azidoselenenylation of alkenes with sodium azide and diselenides, and a series of corresponding β-azidoselenides, most of which are new compounds, have been prepared in moderate to good yields under mild reaction conditions. This in situ generation of the electrophilic selenenylating reagents with addition to alkenes is a stereospecific anti addition, which occurs with a Markovnikov orientation.

The corrosion protection properties of environmentally friendly phytic acid conversion coatings were studied on 2024-T3 aluminium alloy. The films were prepared under acidic conditions with various pH values and characterised by SEM, EDS, ATR-FTIR and electrochemical techniques. The results indicate that the conversion coatings obtained by immersing the alloy in phytic acid solutions at pH from 3 to 5.5 provide excellent corrosion resistance. ATR-FTIR confirms that the film is formed by deposition of reaction products between Al3+ and phosphate groups in phytic acid molecules. The conformation models of the deposition film are proposed. (C) 2013 Elsevier B.V. All rights reserved.

It is reported in this paper that a cavity-dumped electro-optically Q-switched Tm:LuAG oscillator offers a unique combination of high power, constant short pulse duration, and high repetition rate at a wavelength of 2012.7 nm. The constant short pulse durations of 3 ns were achieved by the cavity-dumped technology at different repetition rates from 60 to 100 kHz. An average power of 1.22 W and a peak power of 4.1 kW were obtained at a repetition rate of 100 kHz and an incident pump power of 42.3 W, corresponding to the slope efficiency of 6% and beam quality factor of M2∼1.4. In addition, the accumulation time of intracavity photons from 500 to 1000 ns was studied for the performance of the output characteristic.