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Modulating the length and position of plasma filament is desired for many filament-based applications. We proposed a novel method to manipulate the properties of filament along the propagation direction by introducing asymmetric focusing with a wedge plate in the forced focusing region. By simply varying the inclination degree of a wedge and the distance between the wedge and lens, a plasma filament can break into two sub-filaments along the propagation direction, and the separation between sub-filaments can be controlled. The experiment results are in agreement with the results of simulation by the ray-tracing method. Furthermore, the effect of the wedge angle and rotation angle on the control of the filament is studied. It is found that the separation of the sub-filaments and the azimuth angle of the filament around the original optical axis can be controlled by the wedge angle and rotation angle of the wedge, respectively. When combined with a phase plate, the control method also shows the ability to modulate the multi-filament array with wavefront modification. Our research provides a simple and flexible method for 3-D control of femtosecond laser filaments for practical applications. [ABSTRACT FROM AUTHOR]

White-light supercontinuum from a femtosecond laser filamentation is essential for many applications due to its broadening spectrum and remote sensing ability. We propose to enhance the supercontinuum intensity by presetting the gaseous lattice in the path of femtosecond laser filamentation. Our results show that the introduction of a gaseous lattice can increase the spectral intensity in both visible and infrared wings, up to about ten times over the no lattice case in a gas medium. We find that the gaseous lattice dramatically affects the time-domain evolutions of the optical intensity and the electron density during the nonlinear propagation of the pulse, thereby resulting in spectral intensity enhancement. The results provide a new way to enhance the supercontinuum generation in the ultra-intense nonlinear process by using a gaseous pre-lattice with a special spatial refractive index profile. [ABSTRACT FROM AUTHOR]

The traditional image quality assessments, such as the mean squared error (MSE), the signal-to-noise ratio (SNR), and the Peak signal-to-noise ratio (PSNR), are all based on the absolute error of images. Structural similarity (SSIM) index is another important image quality assessment which has been shown to be more effective in the human vision system (HVS). Although there are many essential differences between MSE and SSIM, some important associations exist between them. In this paper, the associations between MSE and SSIM as cost functions in linear decomposition are investigated. Based on the associations, a bit-allocation algorithm for sparse coding is proposed by considering both the reconstructed image quality and the reconstructed image contrast. In the proposed algorithm, the space occupied by a linear coefficient of a basis in sparse coding is reduced to only 9 to 10 bits, in which 1 bit is used to save the sign of linear coefficient, 3 bits are used to save the number of powers of 10 in scientific notation, and only 5 to 6 bits are used to save the significance digits. The experimental results show that the proposed bit-allocation algorithm for sparse coding can maintain both the image quality and the image contrast well. [ABSTRACT FROM AUTHOR]

The activation energy and ligand reorganization energy for nonadiabatic electron transfer reactions in chemical and biological systems are investigated in this paper. The free energy surfaces and the activation energy are derived exactly in the general case in which the ligand vibration frequencies are not equal. The activation energy is derived by free energy minimization at the transition state. Our formulation leads to the Marcus-Hush [J. Chem. Phys. 24, 979 (1956); 98, 7170 (1994); 28, 962 (1958)] results in the equal-frequency limit and also generalizes the Marcus-Sumi [J. Chem. Phys. 84, 4894 (1986)] model in the context of studying the solvent dynamic effect on electron transfer reactions. It is found that when the ligand vibration frequencies are different, the activation energy derived from the Marcus-Hush formula deviates by 5%–10% from the exact value. If the reduced reorganization energy approximation is introduced in the Marcus-Hush formula, the result is almost exact. [ABSTRACT FROM AUTHOR]

Polyimide (PI), graphite and copper powder mixed in different proportion filled polytetrafluoroethylene (PTFE) to form a new composite material, respectively in MMU-2 friction and wear testing machine for tribological performance tests, and will wear after sample in JMS-5600 scanning electron microscope observation of friction surface grinding crack and transfer of composite materials, and determine the best proportion. In order to study the influence of test conditions on the tribological properties of materials, the optimal ratio of PTFE matrix composites was tested again by changing test conditions. The results show that polyimide can enhance the wear resistance of PTFE, and increase the strength of the transfer film binding to the dual parts. When the mass fraction of PI is 25%, graphite mass fraction is 5%, and Cu powder mass fraction is 5%, the tribological performance of the material is the best. When the sliding velocity is more than 4.5 m/s, the load is greater than 300 N, the sample surface temperature were greater than 120 °C, composite material has entered into the phase of high temperature and friction, the friction surface creep, transfer film a burning phenomenon. [ABSTRACT FROM AUTHOR]

Nanoscale zero-valent iron particles have large specific surface area and high reaction activity, and have been increasingly used for the degradation of environmental contaminants. However, rapid aggregation and deactivation hinder their wide applications. In this work, nanoscale zero-valent iron (NZVI) particles were prepared in vesicles, which were formed by self-assembly of amphiphilic block copolymer poly(1-vinylpyrrolidone-co-vinylacetate) (PVV) in aqueous tetrahydrofuran medium, and characterized with the aid of XRD, FTIR, SEM-EDX, TEM, XPS and DLS techniques. It was found that the NZVI particles were well encapsulated in the vesicles, and they could be stored directly in the air as solids, but the dried NZVI particles could be easily released from the vesicles once they were put in water. These NZVI particles showed some unique features, such as uniform nanometer size distribution (from 70 to 100 nm), vesicle-like morphology, and good dispersion. Activity and stability of the NZVI in vesicles were examined by using Cr(VI) and nitrobenzene as the model pollutants, and compared with the bare NZVI particles synthesized with the same procedures but without PVV. A dramatic difference in activity and stability was observed for the two different NZVI particles. The NZVI in vesicles showed a good chemical stability in the air, and still maintained its high reactivity in water. Such excellent performance might be attributed to the encapsulation of the NZVI by vesicles, which could impede well the strong agglomeration of metal particles in water and prevent metal particles from being oxidized in the air. [ABSTRACT FROM AUTHOR]

As a structure-based image compression technology, fractal image compression (FIC) has been applied not only in image coding but also in many important image processing algorithms. However, two main bottlenecks restrained the develop and application of FIC for a long time. First, the encoding phase of FIC is time-consuming. Second, the quality of the reconstructed images for some images which have low structure-similarity is usually unacceptable. Based on the absolute value of Pearson’s correlation coefficient (APCC), we had proposed an accelerating method to significantly speed up the encoding of FIC. In this paper, we make use of the sparse searching strategy to greatly improve the quality of the reconstructed images in FIC. We call it the sparse fractal image compression (SFIC). Furthermore, we combine both the APCC-based accelerating method and the sparse searching strategy to propose the fast sparse fractal image compression (FSFIC), which can effectively improve the two main bottlenecks of FIC. The experimental results show that the proposed algorithm greatly improves both the efficiency and effectiveness of FIC. [ABSTRACT FROM AUTHOR]

Development of novel technologies for the efficient and reversible capture of CO2 is highly desired. In the last decade, CO2 capture using ionic liquids has attracted intensive attention from both academia and industry, and has been recognized as a very promising technology. Recently, a new approach has been developed for highly efficient capture of CO2 by site-containing ionic liquids through chemical interaction. This perspective review focuses on the recent advances in the chemical absorption of CO2 using site-containing ionic liquids, such as amino-based ionic liquids, azolate ionic liquids, phenolate ionic liquids, dual-functionalized ionic liquids, pyridine-containing ionic liquids and so on. Other site-containing liquid absorbents such as amine-based solutions, switchable solvents, and functionalized ionic liquid–amine blends are also investigated. Strategies have been discussed for how to activate the existent reactive sites and develop novel reactive sites by physical and chemical methods to enhance CO2 absorption capacity and reduce absorption enthalpy. The carbon capture mechanisms of these site-containing liquid absorbents are also presented. Particular attention has been paid to the latest progress in CO2 capture in multiple-site interactions by amino-free anion-functionalized ionic liquids. In the last section, future directions and prospects for carbon capture by site-containing ionic liquids are outlined. [ABSTRACT FROM AUTHOR]

Some potential applications require controllable curved femtosecond laser filaments. We show how a gas lattice medium with periodic refractive index profiles can generate a serpentine filament array of a femtosecond laser Gaussian pulse. The simulation findings show that the curved characteristics (bending times and degree), spatial evolution (onset, termination and interval) and energy fluence profiles of the filaments, can be flexibly controlled by adjusting the various parameters of the gas lattice. When collapsing Gaussian laser pulse is coupled into the asymmetric gas lattice, the optical waveguide effect in a medium with a refractive index gradient plays a vital role in forming the continuously curved trajectory. By adjusting the gas lattice parameters, serpentine filaments with customised characteristics can also be obtained. Our research provides a new method for manipulating the strong nonlinear propagation trajectories, which is for the first time to tailor serpentine filaments by utilising a modulated dielectric medium and offers a unique solution for many potential applications. [ABSTRACT FROM AUTHOR]

The flexible control of femtosecond laser filamentation is crucial for many practical and promising applications. We have demonstrated a simple method to control arbitrarily the onset and the terminal positions of femtosecond laser filament in the fused silica by tailoring the profile of the annular Bessel beam. The tailoring of the inner and outer radius of the annular beam is realized by amplitude mask and iris diaphragm respectively before the axicon. Our experiments have shown that the onset of the filamentation can be modulated by changing the inner radius of the laser beam, and the filamentation termination is determined by the outer radius of the annular beam. Moreover, the results show that the onset and terminal positions of the filaments are positively correlated with the inner and outer radius of the beam, respectively, which facilitate the arbitrary start and length control of the filament in the experiment. In addition, this arbitrary regulation of the onset and termination of the filamentation is being negligibly affected by incident laser power that is lower than the damage threshold of fused silica. The flexible control of filamentation enabled by the simple method is beneficial to many applications. [ABSTRACT FROM AUTHOR]

Fractal image compression (FIC) technology is an interesting attempt at structure similarity-based image compression. It has been widely applied in many fields such as image encryption, image retrieval, image sharpening, and pattern recognition. However, overlong encoding time is the main difficulty for the application of FIC. In this paper, a new FIC speedup algorithm is proposed with two steps. Firstly, the simplified statistical variable expressions can speed up encoding twice more than the baseline fractal compression (BFC) without loss of image quality corresponding to BFC. Secondly, based on the fact that the affine self-similarity is equivalent to the absolute value of Pearson's correlation coefficient, a new block classification strategy with flexible classification sets is proposed to speed up encoding further. The experiment results and theoretical analysis show that the proposed scheme achieves high performance in both image quality preservation and encoding efficiency. [ABSTRACT FROM AUTHOR]

Abstract: Many applications of ionic liquids (ILs) are closely related with their microstructure in mixtures. For example, morphology and pore size of the MCM-41 prepared in aqueous ILs are greatly dependent on the aggregation behavior of the ILs in water. Therefore, the study on the microstructure of ILs in aqueous solutions is of great importance. In this work, 1H NMR, dynamic light scattering and attenuated total reflection infrared spectroscopy have been used to investigate the temperature effect on the structures of aqueous 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) solutions. It was shown that the size of the IL aggregates becomes larger with decreasing temperature. When the system temperature is below the upper critical solution temperature (UCST) of the binary mixture at about 4°C, the aggregate size of the IL is larger than 1000nm. Additionally, the two-dimensional IR results reveal that at low IL concentrations, H2O can interact with [BF4]− prior to the C H groups of the imidazolium ring, whereas cation and anion of the IL tend to form aggregate at high IL concentrations. With the decrease of temperature, the interactions between cation and anion of the IL become stronger, but those between the IL and water become weaker, thereby resulting in the growth of the aggregate of cation with anion of the IL. This result may give a reasonable explanation for the origin of the UCST behavior of aqueous [C4mim][BF4] solution. [Copyright &y& Elsevier]

Highlights: [•] Glycine ILs [N5555][Gly], [P4444][Gly], [N4444][Gly] and [N2222][Gly] were prepared. [•] Partition coefficients of DNP-amino acids and cytochrome-c were determined in glycine ILs/K2HPO4 ATPSs. [•] Gibbs energies of transfer of methylene between the two phases were calculated. [•] Hydrophobic interaction is the main driving force for the efficient partition of the protein in the IL-rich phases. [ABSTRACT FROM AUTHOR]

Abstract: In recent years, numerous fractal image compression (FIC) schemes and their applications in image processing have been proposed. However, traditional FIC ignores the importance of affine parameters in the iterated function system (IFS) and affine parameters are kept invariant for a certain image in almost all of these schemes. By analyzing fractal compression technology in this paper, we show that the affine parameters in IFS can vary with different image quality measurements. A positive correlation exists between the image contrast of fractal decoded image and affine scalar multiplier. This strong correlation demonstrates that an image can be sharpened or smoothed using fractal compression technology. [Copyright &y& Elsevier]

In this work, densities and viscosities for the binary mixtures of 1-octyl-3-methylimidazolium tetrafluoroborate, [Cmim][BF], with butanone, methyl acetate, ethyl acetate, propyl acetate and butyl acetate have been determined at 298.15 K. These data were used to calculate the excess molar volumes $$ V_{m}^{\text{E}} $$ and the viscosity deviations (ln η) for the mixtures. It is shown that values of $$ V_{m}^{\text{E}} $$ are negative, while those of (ln η) are positive in the whole concentration range. The $$ V_{m}^{\text{E}} $$ values show their minimum at the composition of x ≈ 0.3, and the (ln η) values exhibit a maximum at the same mole fraction. For the binary systems, the absolute values of $$ V_{m}^{\text{E}} $$ decrease in the order: butanone > methyl acetate > ethyl acetate > propyl acetate > butyl acetate, whereas those of (ln η) decrease in the order: methyl acetate > ethyl acetate > propyl acetate > butyl acetate > butanone. The results are discussed in terms of the ion-dipole interactions between cations of the ionic liquid and the organic molecules and hydrogen bonding interactions between anions of the ionic liquid and the organic compounds. [ABSTRACT FROM AUTHOR]

Densities for solutions of [Cnmim]Br(n= 4, 8, 10, 12) ionic liquids (ILs) in dimethylsulfoxide (DMSO) have been determined as a function of ionic liquidconcentration at the temperature T= (293.15, 298.15,303.15, 308.15, and 313.5) K and atmospheric pressure. The apparentmolar volumes, apparent molar volumes at infinite dilution, and limitingapparent molar expansivities of the ILs have been obtained from theexperimental density data. These data were used to understand theeffect of the alkyl chain length of the ILs and experimental temperatureon the IL–DMSO interactions occurring in the studied solutions.It was shown that the apparent molar volumes at infinite dilutionincreased with increasing alkyl chain length of the ILs and temperatureof the systems. Furthermore, the values of the limiting apparent molarexpansibilities were found to be positive and decreasewith increasing temperature. [ABSTRACT FROM AUTHOR]

Carboxylate-anion-based imidazolium ionic liquids (ILs)are powerfulsolvents for cellulose and lignin. However, little is known abouttheir fundamental physicochemical properties. In this work, 1-butyl-3-methylimidazoliumcarboxylate ILs 1-butyl-3-methylimidazolium formate ([C4mim][HCOO]), acetate ([C4mim][CH3COO]), propionate([C4mim][CH3CH2COO]), and butyrate([C4mim][CH3(CH2)2COO]),in which the alkyl chain length in the anions is being varied in contrastto the more usual studies where alkyl chain length in the cationsis varied, have been synthesized and their densities and surface tensionshave been determined experimentally at different temperatures. Byusing these data, the molar volume, isobaric expansivity, standardentropy, lattice energy, surface excess entropy, vaporization enthalpy,and Hildebrand solubility parameter have been estimated for theseILs. From the analysis of structure–property relationship,the effect of alkyl chain length in the anions on these physicochemicalproperties of the ILs has been assessed and the dissolution of celluloseand lignin in these ILs has been discussed. Such knowledge is expectedto be useful for understanding the nature of this class of solventfor the dissolution of biomacromolecules. [ABSTRACT FROM AUTHOR]

Abstract: Compared with the conventional ionic liquids, amino acid ionic liquids are more biodegradable and biocompatible, and can enhance stability of biomaterials. In this work, amino acid ionic liquids 1-butyl-3-methylimidazolium l-serine ([C4mim][Ser]), 1-butyl-3-methylimidazolium glycine ([C4mim][Gly]), 1-butyl-3-methylimidazolium l-alanine ([C4mim][Ala]) and 1-butyl-3-methylimidazolium l-leucine ([C4mim][Leu]) have been synthesized. These ionic liquids are found to form aqueous two-phase systems (ATPSs) by the salted-out of K3PO4 in aqueous solutions. Phase diagram of the ATPSs and the Gibbs energies of transfer of methylene group from the bottom salt-rich phase to the top ionic liquid-rich phase have been determined at 298.15K and pH 14, and the effect of anionic structure of the ionic liquids on phase formation of the ATPSs and the relative hydrophobicity between the top and the bottom phases are then examined. In order to understand the effect of relative hydrophobicity of the phases in equilibrium in the ATPSs on the extraction/separation capability of biomolecules, the partition coefficients of cytochrome-c (as a model biomolecule) in the ATPSs are measured by spectrophotometry. It is suggested that hydrophobic interactions are mainly responsible for the higher partition coefficients of cytochrome-c in aqueous two-phase systems at pH 14, and the extraction and separation capacity of biomolecules can be improved by the modulation of the relative hydrophobicity of the phases and/or the pH of the system. [Copyright &y& Elsevier]

Material preparation in ionic liquids and environmental pollution control by ionic liquids are often closely dependent on the aggregation behavior of ionic liquids in solution. In the present work, conductivity, fluorescence probe, and dynamic light scattering techniques have been used to study the effect of organic solvents on the aggregation behavior of 1-dodecyl-3-methylimidazolium bromide in water. It was shown that the critical aggregation concentration (CAC), the ionization degree of the aggregates (α), and the standard Gibbs energy of aggregation (ΔGm°) of the ionic liquid increase, while its aggregation number (Nagg) and aggregates’ size decrease with increasing concentration of organic additives in water. These results have been discussed from the favorable interactions of alkyl chain of the ionic liquid with the mixed solvents. It is suggested that the solvophobic parameter, characterized quantitatively by Gibbs energy of transfer of hydrocarbon from gas into a given solvent, can be used to account for the effect of organic additives on the formation and growth of the ionic liquid aggregates in water. Aggregation behavior of ionic liquids in aqueous organic solutions can be modulated simply by the solvophobic parameters of hydrocarbon in the mixed solvents. [ABSTRACT FROM AUTHOR]

Abstract: Information on the interactions between ionic liquids and molecular solvents are essential for the understanding of the function of ionic liquids in related procedures, and excess properties are sensitive probe for these interactions. In this work, excess molar volume and excess logarithmic viscosity ((ln η)E) for the binary mixtures of 1-hexyl-3-methylimidazolium tetrafluoroborate ([C6mim][BF4]) with butanone, ethyl acetate, butylamine, and tetrahydrofuran have been determined from density and viscosity measurements in the whole composition range at the temperature of 298.15K. It is found that for the studied systems, the values of are negative but those of (ln η) E are positive in the whole concentration range. The values show their minimum at the ionic liquid mole fraction of 0.3, and (ln η) E values exhibit a maximum at the same composition. The absolute values of follow the sequence: tetrahydrofuran>butanone>ethyl acetate>butylamine for the binary systems, whereas the values of (ln η) E decrease in the order: tetrahydrofuran>butylamine>ethyl acetate>butanone. The results have been analyzed through the ion–dipole interaction, the hydrogen bonding, the packing efficiency and the ion-pairs exist in the ionic liquid. [Copyright &y& Elsevier]

Abstract: Relatively large percentages of xylose with glucose, arabinose, mannose, galactose and rhamnose constitute the hydrolysis products of hemicellulose. In this paper, hydrogen production performance of facultative anaerobe (Enterobacter aerogenes) has been investigated from these different monomeric sugars except glucose. It was shown that the stereoisomers of mannose and galactose were more effective for hydrogen production than those of xylose and arabinose. The substrate of 5g/l xylose resulted in a relative high level of hydrogen yield (73.8mmol/l), hydrogen production efficiency (2.2mol/mol) and a maximum hydrogen production rate (249ml/l/h). The hydrogen yield, hydrogen production efficiency and the maximum hydrogen production rate reached 104mmol/l, 2.35mol/mol and 290ml/l/h, respectively, on a substrate of 10g/l galactose. The hydrogen yields and the maximum hydrogen production rates increased with an increase of mannose concentrations and reached 119mmol/l and 518ml/l/h on the culture of 25g/l mannose. However, rhamnose was a relative poor carbon resource for E. aerogenes to produce hydrogen, from which the hydrogen yield and hydrogen production efficiency were about one half of that from the mannose substrate. E. aerogenes was found to be a promising strain for hydrogen production from hydrolysis products of hemicellulose. [Copyright &y& Elsevier]

Abstract: Ionic liquids have potentials as green materials in a variety of fields. It is the case that in their application in industry, ionic liquids are often used together with molecular solutes/solvents. In this paper, systematical measurements of viscosities and conductivities for the binary and quasi-binary mixtures of ionic liquids with molecular solutes were performed over the whole concentration range. The variation tendency of viscosities/conductivities with composition of the mixtures was explained through the disruption of molecular solutes to ionic association or aggregation of the ionic liquids. A exponential equation with empirical parameter A suggested initially by Seddon et al. was used to describe the dependence of viscosities on the mole fraction of molecular solutes, and the physical meaning of A was analyzed based on a theoretical equation deduced from rate process theory. At the same time, another exponential equation with parameter C was proposed to correlate the experimental date of the product of conductivity and viscosity, and satisfactory results were obtained over the entire range of concentration. The main factors affecting the parameter C were discussed. It is expected that the new data and correlation equations reported in this work will be useful for the application of ionic liquids in chemical industry. [Copyright &y& Elsevier]

Abstract: As an effective extraction method, aqueous two-phase extraction systems based on imidazolium ionic liquids have been used, in this work, to extract proteins of bovine serum albumin, trypsin, cytochrome c and γ-globulins. Effects of the ionic liquids concentration, pH value, and temperature of the systems on the extraction efficiencies have been investigated. Experimental results show that 75–100% of the proteins could be extracted into the ionic liquid-rich phase in a single-step extraction. The extraction efficiency of cytochrome c was changed slightly with the increase of pH values. Extraction efficiencies of the proteins were found to increase with increasing temperature and increasing alkyl chain length of cation of the ionic liquids. Thermodynamic studies indicated that hydrophobic interactions were the main driving force, although electrostatic interactions and salting-out effects were also important for the transfer of the proteins. Importantly, conformation of the proteins was not affected after extraction into the upper ionic liquid-rich phase as determined by UV–visible (UV–vis) and Fourier transform infrared (FT-IR) spectroscopy of the proteins. The enzyme activity of native trypsin and the trypsin in ionic liquids was determined using N-α-benzoyl-l-arginine ethyl ester as a substrate. This novel process is suggested to have important applications for the separation of proteins. [Copyright &y& Elsevier]

Abstract: The polymer–ammonium complexes are an important class of proton conducting polymer electrolytes. In this work, poly(ethylene oxide) (PEO)–NH4SCN electrolytes were prepared over a large range of the salt content, and their FT-IR spectra were measured at room temperature. Based on the assignments of each band in the spectral envelope of SCN−1, their relative intensities are determined by the use of FT-IR technique. Following the experimental results and spectral analyses, this paper reports the interactions, the various ionic associations, the changes of the ionic association with NH4SCN content, and the characteristics of structure in PEO–NH4SCN electrolytes. It is shown that the hydrogen bonds of PEO and NH4SCN exert the great effect to the ionic association, the interactions of PEO with NH4SCN, and PEO crystallinity, in particular, under the condition of high NH4SCN content. In addition, the differences of ionic association among PEO–NaSCN, PEO–KSCN and NH4SCN electrolytes are also compared in this paper. [Copyright &y& Elsevier]

Unstable random multi-filament distribution by free propagation of high power femtosecond laser in transparent medium is unfavorable to the filamentation applications and controllable regular multi-filament array is desired. Here, we present a novel method to modulate the spatial distribution of multi-filament by a phase plate-assisted interference of two delayable femtosecond laser pulses. The experimental results show that regular femtosecond laser multifilament array can be realized and the array can be conveniently converted from one patten to another with the varying of the delay of the two laser pulses. It is found that the spatiotemporal phase variation of the interference beam is responsible for this control process. This work provides a new way to regulate the spatial distribution of multi-filament by simply varying relative phase of the two laser beams and holds a great flexibility for a filament array in many applications. [ABSTRACT FROM AUTHOR]

Abstract: Apparent molar volumes V 2,ϕ and standard partial molar volumes V 2,ϕ 0 of LiBF4 have been determined at 298.15K from precise density measurements in propylene carbonate (PC) or ethylene carbonate (EC) based mixed solvents. The chosen cosolvents were dimethylformamide (DMF), tetrahydrofuran (THF), acetonitrile (AN), 1,2-dimethoxyethane (DME) and ethyl acetate (EA). The results have been interpreted from solvation of LiBF4 in carbonate based mixed solvents. It is shown that nature of the cosolvents plays an important role for the concentration dependence of V 2,ϕ 0 values. Compared with the previous studies, the differences between ClO4 − and BF4 − have been embodied in the concentration dependence of V 2,ϕ 0 values and also interpreted by the interaction of the anion with solvents. [Copyright &y& Elsevier]

Abstract: The polymeric conformations can provide insight into the structure and the mechanism of ion transport in solid polymer electrolytes. In this work, the FT-IR spectra of PEO–NaSCN complexes were measured at room temperature, and the solvation of NaSCN in PEO was revealed by the conformational changes of PEO with NaSCN content. It is suggested that the complexation of PEO with NaSCN can occur through three modes: trans-coordination, gauche-coordination, and cryptande-coordination, depending on the conformation and the flexibility of PEO backbone. The trans-coordination is a weak solvation and can cause the interchain crosslinking and the reduction of segmental motion. The gauche-coordination is a strong complexation and can form complexes in which Na+ is wrapped by the PEO helix. The cryptandes result from the internal rotation of the flexible PEO backbone and can interact directly with NaSCN to form triple ion aggregations, especially when the salt content is low in PEO. In addition, the effect of PEO crystallinity on solvation and the solvating ability of PEO with different molecular weight are discussed also in this paper. [Copyright &y& Elsevier]

Abstract: The standard partial molar volumes, viscosity B-coefficients and activation free energies of lithium salts (LiClO4 and LiBr) in propylene carbonate (PC) with 1,2-dimethoxyethane (DME) mixed solvents have been determined as a function of the mole fraction of DME at 298.15K from precise density and viscosity measurements. The values studied are all positive and decrease monotonously with addition of DME in the PC, which indicates that nature of the solvents plays an important role. The effects are discussed in terms of preferential solvation and packing effect in the solvation shell and electrostriction. The differences between ClO4 − and Br− have also been discussed. [Copyright &y& Elsevier]

Abstract: Solid polymer electrolytes are potentially useful electrolytes to be applied in high-energy batteries. In the present work, a novel polymer electrolyte, polyethylene oxide (PEO)–NaSCN–AlCl3, was prepared and investigated by FT-IR spectroscopic techniques. Based on the FT-IR data, the bands in the CN stretching envelope have been assigned and the effect of AlCl3 on ion–ion and ion–polymer interactions in the polymer electrolyte has been examined. It is shown that the Lewis acid–base interaction of AlCl3 with SCN1− leads to the formation of the complex anions AlCl3SCN− and Al2Cl6SCN−, depending on the content of AlCl3 and/or NaSCN in PEO; the preferential interactions of AlCl3 with crystal complex P(EO)3NaSCN occur in PEO–NaSCN–AlCl3 electrolytes; the AlCl3–NaSCN complex anions can play a plasticization role in PEO–NaSCN–AlCl3 electrolyte, and are expected to be a important factor to improve the conductivity and to enhance the cation transference number. In addition, the interactions between AlCl3 and ether oxygen of PEO were analyzed, and their effect on ionic association was also discussed. [Copyright &y& Elsevier]

Abstract: Solutions of sodium tetrafluorobrate in acetonitrile–dimethylformamide, and acetonitrile–dimethylsulfoxide mixtures have been studied by FT-Raman spectroscopy for three solvent compositions, respectively. New bands due to solvent molecules in the first solvation shell of Na+ were detected in the region of the Oh name="sbnd" />N deformation and CH3 rocking mode for amide and of the Se:glyph name="sbnd" />S stretching modes for sulfoxide. The individual solvation numbers of sodium cation in different environment were deduced. In all the cases, it is found that the sodium ion was preferentially solvated by DMF or DMSO in respective binary solvents. This result was further supported by ab initio calculations. [Copyright &y& Elsevier]

Abstract: The structures, vibrational frequencies, infrared and Raman intensities of hexafluorophosphate anion (PF6 −) and M+PF6 − (M+ =Li+, Na+, K+, Rb+ and Cs+) ion pairs have been studied by ab initio calculations. It is shown that the tridentate coordination of cation by PF6 − is the most stable structure in gas phase. The vibrational spectroscopies of the most stable geometries were calculated and the changes in band position were used to probe the ion associations. [Copyright &y& Elsevier]

The apparent molar volumes (Vm,2) and relative viscosities (ηr) at T=(298.15 and 308.15) K have been obtained for glycine, dl-α-alanine, and dl-α-amino-butyric acid in aqueous sodium caproate solutions from measurements of density and the flow time. The standard partial molar volumes (V∘m,2), standard volumes of transfer (ΔtV∘), the viscosity B-coefficients, and the activation thermodynamic quantities (Δμ2∘≠ and ΔS2∘≠) of viscous flow have been calculated for the amino acids. It is shown that the standard partial molar volumes, viscosity B-coefficients, and activation free energies for viscous flow increase with increasing number of carbon atoms in the alkyl chain of the amino acids. An increase in V∘m,2 and ΔtV∘ with increasing electrolyte concentrations have been explained due to the interactions of sodium caproate with the charged center of zwitterions for the amino acids. A comparison of the V∘m,2 values for glycine, dl-α-alanine, and dl-α-aminon-n-butyric acid in different aqueous salts solutions showed that carboxylate ions have stronger interactions with amino acid than chloride, thiocyanate, and nitrate ions. Results of viscosity are discussed in terms of changes in solvent structure. [Copyright &y& Elsevier]

Densities and viscosities for solutions of some α-amino acids in aqueous calcium chloride (3.0 mol kg−1) have been determined at 278.15, 288.15, 298.15 and 308.15 K. These data have been used to calculate apparent molar volumes and viscosity B-coefficients of the amino acids. The standard partial molar volumes, V°2,φ, and hydration numbers of the amino acids have been determined at different temperatures. Free energies of activation, Δμ°2≠, for viscous flow of the solutions were obtained by application of the transition-state theory to the B-coefficient data, and the corresponding activation enthalpy ΔH°2≠ and entropy ΔS°2≠ were also given. It has been shown that V°2,φ, B-coefficients and the free energies of activation vary linearly with increasing number of carbon atoms in the alkyl chain of the amino acids, and they were split into contributions from the zwitterionic end group (NH3+, COO−) and the methylene groups of the amino acids. The volumetric data have been interpreted in terms of the hydration of the hydrophobic and hydrophilic parts of the amino acids. From the viscosity data, structural effects of the amino acids in the solutions have been discussed. [Copyright &y& Elsevier]

Apparent molar volumes V2,φ and standard partial molar volumes V2,φ0 of LiClO4, LiBr and three symmetrical tetraalkylammonium bromides R4NBr (R=ethyl, propyl, butyl) have been determined at 298.15 K from precise density measurements in solvent mixtures of ethylene carbonate with tetrahydrofuran (THF), acetonitrile (AN), ethyl acetate (EA) and dimethoxyethane (DME). It is shown that the V2,φ0 values of LiClO4 and LiBr are dependent strongly on the nature of the solvents, whereas the contribution of CH2 group to the partial molar volume of the tetraalkylammonium salts has nothing to do with the nature of the solvents and the composition of the solvent mixtures. This provided a helpful evidence for the unsolvation of large tetraalkylammonium cations in organic solvents. The results have been discussed from ion–solvent interactions and the dielectric effect of the solvents. [Copyright &y& Elsevier]

Viscosities of glycine, dl-α-alanine, dl-α-amino-n-butyric acid, dl-valine and dl-leucine have been determined in water–sodium acetate mixtures at 298.15 and 308.15 K. The viscosity B-coefficients have been calculated. The corresponding activation free energies (Δμ20≠) for viscous flow have been evaluated with the help of the Feakins equation. The contributions of the charged end group (NH3+,COO−) and CH2 groups of the amino acids to B-coefficient and Δμ20≠ have been also determined using the linear correlation between B-coefficient or Δμ20≠ and the number of carbon atoms in alkyl chains of the amino acids. The results have been interpreted in the light of the solute–solvent interactions in aqueous media. [Copyright &y& Elsevier]

FTIR spectra have been recorded and analyzed for solutions of lithium perchlorate in propylene carbonate (PC), diethyl carbonate (DEC), and PC+DEC mixtures. It has been shown that the carbonyl stretch bands for PC and DEC are very sensitive to the interaction between Li+ and the solvent molecules. They split with addition of LiClO4, indicating a strong interaction of Li+ with PC and DEC through the oxygen group of PC and both oxygen and ether oxygen atoms of DEC. In conjunction with molecular orbital calculation, the optimized geometries of solvation are given. In addition, solvent separated ion pairs and contact ion pairs were observed in LiClO4/DEC solutions, and no preferential solvation of Li+ in LiClO4/PC+DEC solutions were detected. [ABSTRACT FROM AUTHOR]

Apparent molar volumes (V[sub 2, f] ) and standard partial-molar volumes (V[sub 2] [sup 0] [sub , f] ) of LiClO[sub 4] and LiBr at 298.15 K have been determined from precise density measurements in solvent mixtures of propylene carbonate (PC) with dimethylformamide (DMF), tetrahydrofuran (THF), acetonitrile (AN), and methyl formate (MF). The scaled particle theory is used to calculate the contributions of the cavity formation and the electrolyte-solvent interactions to the standard partial-molar volumes. It is shown that V[sub 2] [sup 0] [sub , f] is strongly dependent on the nature of the solvents, and the trends in V[sub 2] [sup 0] [sub , f] with composition of the solvent mixtures are determined by the interaction volumes of electrolytes with solvents. The results are discussed in terms of ionic preferential solvation, packing effect of solvents in the solvation shell, and electrostriction of solvents by ion.Key words: partial-molar volume, scaled particle theory, lithium salts, propylene carbonate, solvent mixtures, lithium battery electrolytes.En se basant sur des mesures précises de densité dans des mélanges de solvants de carbonate de propylène (PC) avec du diméthylformamide (DMF), du tétrahydrofurane (THF), de l'acétonitrile (AN) et de formiate de méthyle (MF), on a déterminé les volumes molaires apparents (V[sub 2, f] ) et les volumes molaires partiels standards, (V[sub 2] [sup 0] [sub , f] ) du LiClO[sub 4] et du LiBr, à 298,15 K. On a utilisé la théorie de la particule pour calculer les contributions de la formation de la cavité et de l'interaction de l'électrolyte-solvant aux volumes molaires partiels standards. On a démontré que la valeur de V[sub 2] [sup 0] [sub , f] , dépend fortement de la nature des solvants et les tendances dans les valeurs de V[sub 2] [sup 0] [sub , f] avec la composition des mélanges de solvant sont déterminées ceux qui sont présents dans les volumes d'interaction des électrolytes avec les solvants. On discute des résultats sur la base de la solvatation ionique préférencielle, de l'effet du tassement des solvants dans la couche de solvatation et de l'électrostriction des solvants par l'ion.Mots clés : volume molaire partiel, théorie de la particule scalaire, sels de lithium, carbonate de propylène, mélanges de solvants, électrolytes de piles au lithium.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

The utilization of CO2 from flue gas as a C1 feedstock for the catalytic synthesis of high-valued oxazolidinones is highly important but challenging due to the low CO2 concentration and high activation barrier for CO2. Herein, we present an efficient and stable CuI-anchored porous covalent organic framework CuI@TpBD-COF for effective catalysis of the carboxylic cyclization reaction between propargylic amines and CO2 to produce various functionalized oxazolidinone derivatives under mild conditions. The yield is up to 99% and the turnover frequency (TOF) reaches a record value of 1058 h−1, significantly surpassing almost all previously reported metal heterogeneous catalysts. Furthermore, CuI@TpBD-COF also demonstrates efficient catalytic activity when simulated flue gas is used as the source of CO2. This work provides new guidance for the design of more efficient and eco-friendly noble-metal-free catalytic materials to drive the ideal CO2 chemical fixation process. [ABSTRACT FROM AUTHOR]

Looks at a study which synthesized the marine metabolites verongamine, hemibastadin-2, and aerothionin. Details on the conversion process of a carboxylic acid into an acyl cyano phosphorane; Conversion of the electrophilic intermediate to alpha-keto amides, by amines; Methodology used to conduct the study; Results of the study.

Presents research on the aerobic and anaerobic biosynthesis of vitamin B 12. Materials and methods of experiment; Results; Discussion.

Using LiHMDS as the base, a tandem amidation/Knoevenagel condensation of 2-aminobenzophenones with α-methylene esters or lactones gives 4-aryl-quinolin-2(1H)-ones in 65–96% yield. This method is mild, highly efficient, and amenable to scaleup. [Copyright &y& Elsevier]

Background: Knee osteoarthritis (KOA) is one of the most common chronic diseases in the elderly and is the primary cause of the loss of motor function and disability in this population. Exercise therapy is a core, basic and matureand treatment method of treating patients with KOA. Exercise therapy is "strongly recommended" or "recommended" in the diagnosis and treatment guidelines of osteoarthritis in many countries, and most scholars advocate exercise therapy as the preferred rehabilitation method for KOA patients. However, poor long-term adherence is a serious problem affecting the therapeutic effect of this mature treatment. The objective of this study was to construct a concise and practical adherence rating scale (ARS) based on the exercise therapy adherence prediction model in patients with knee osteoarthritis.Methods: A binary logistic regression model was established, with the adherence of 218 cases of KOA patients as the dependent variable. The patients' general information, exercise habits, knowledge, attitude, and exercise therapy were independent variables. The regression coefficients were assigned to various variables in the model, and the ARS was constructed accordingly. Receiver operating characteristic curves and curve fitting were used to analyse the effect of the ARS in predicting the adherence and to determine the goodness of fit for the adherence. The external validity of the ARS was examined in a randomized controlled trial.Results: The construction of the adherence model and the ARS included the following variables: age (1 point), education level (1 point), degree of social support (2 points), exercise habits (3 points), knowledge of KOA prevention and treatment (2 points), degree of care needed to treat the disease (1 point), familiarity with exercise therapy (4 points) and treatment confidence (3 points). The critical value of the total score of the ARS was 6.50, with a sensitivity of 87.20% and a specificity of 76.34%.Conclusions: A KOA exercise therapy adherence model and a simple and practical ARS were constructed. The ARS has good internal validity and external validity and can be used to evaluate the adherence to exercise therapy in patients with KOA. [ABSTRACT FROM AUTHOR]

Due to the effectiveness in learning the subspace structures, low-rank representation (LRR) and its variations have been widely applied in various fields, such as computer vision and pattern recognition. However, in real applications, it is a challenge to handle the complex noises. To address this problem, we propose a novel robust LRR method based on kernel risk-sensitive loss (KRSL) with high-order manifold constraint, called RHLRR, in which the KRSL is introduced to deal with the noises and the multiple hypergraph regularization term is used as a high order manifold constraint to effectively capture the locality, similarity and the intrinsic geometric information in data. Besides, an iterative algorithm based on the half-quadratic (HQ) and the accelerated block coordinate update (BCU) is developed. The experimental results demonstrate that the proposed method can outperform other state-of-the-art LRR variants. [ABSTRACT FROM AUTHOR]

Open in new tab Download slide OBJECTIVES The aim of this study was to investigate the early and long-term outcomes after total arch replacement (TAR) and frozen elephant trunk (FET) implantation in adult patients ≤30 years with acute type A aortic dissection (ATAAD). METHODS All young adult patients (≤30 years) with ATAAD who underwent TAR and FET between 2009 and 2017 were enrolled. The end points were major organ morbidity and mortality, aortic-related events and reoperation. RESULTS The mean age of all 83 patients was 25.9 (standard deviation, 3.3) years. The in-hospital mortality was 9.64% (8/83), and 9 (10.8%) patients required re-exploration for bleeding. The aortic-related events risk was 42.7% (32/75) and the aortic reoperation risk was 17.3% (13/75). Overall survival was 85.5% [95% confidence interval (CI), 75.9–91.5%] at 5 years and 75.9% (95% CI, 63.3–84.7%) at 10 years. The cumulative incidence of aortic-related events was 35% (95% CI, 24–47%) at 5 years and 58% (95% CI, 36–75%) at 10 years; the cumulative reoperation rate was 15% (95% CI, 7.9–24%) at 5 years and 17% (95% CI, 9.2–27%) at 10 years. Marfan syndrome significantly increased the aortic-related events (P  =   0.036) and reoperation (P  =   0.041) risks. CONCLUSIONS Despite extensive repair in young ATAAD patients, the late aortic dilatation and reoperation risk remain high. The TAR and FET procedures achieved satisfactory early outcomes and reduced late aortic dilatation and reoperation in young patients compared with other records. Close follow-up and aggressive early reintervention are essential for patients with aortic-related risk factors early in life. [ABSTRACT FROM AUTHOR]

Zero-shot detection (ZSD) aims to locate and classify unseen objects in pictures or videos by semantic auxiliary information without additional training examples. Most of the existing ZSD methods are based on two-stage models, which achieve the detection of unseen classes by aligning object region proposals with semantic embeddings. However, these methods have several limitations, including poor region proposals for unseen classes, lack of consideration of semantic representations of unseen classes or their inter-class correlations, and domain bias towards seen classes, which can degrade overall performance. To address these issues, the Trans-ZSD framework is proposed, which is a transformer-based multi-scale contextual detection framework that explicitly exploits inter-class correlations between seen and unseen classes and optimizes feature distribution to learn discriminative features. Trans-ZSD is a single-stage approach that skips proposal generation and performs detection directly, allowing the encoding of long-term dependencies at multiple scales to learn contextual features while requiring fewer inductive biases. Trans-ZSD also introduces a foreground–background separation branch to alleviate the confusion of unseen classes and backgrounds, contrastive learning to learn inter-class uniqueness and reduce misclassification between similar classes, and explicit inter-class commonality learning to facilitate generalization between related classes. Trans-ZSD addresses the domain bias problem in end-to-end generalized zero-shot detection (GZSD) models by using balance loss to maximize response consistency between seen and unseen predictions, ensuring that the model does not bias towards seen classes. The Trans-ZSD framework is evaluated on the PASCAL VOC and MS COCO datasets, demonstrating significant improvements over existing ZSD models. [ABSTRACT FROM AUTHOR]

Abstract Pb-Zr mixed oxides with 15.2 wt% PbO loading were prepared by four different preparation processes, and their catalytic performances for the disproportionation of methyl phenyl carbonate (MPC) to synthesize diphenyl carbonate (DPC) were evaluated. Physicochemical characterizations including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray fluorescence spectroscopy (XRF), BET surface area measurement, H 2 -temperature programmed reduction (H 2 -TPR), ammonia temperature programmed desorption (NH 3 -TPD) and infrared spectroscopy of pyridine adsorption (Py-IR), as well as catalytic tests of MPC disproportionation reaction showed that catalyst preparation process exerted significant influence on the composition, structural property, catalytic performance of obtained catalysts, and the catalyst prepared by co-precipitation method (PbZr-CP) demonstrated better dispersion of active phase, larger specific surface area and more Lewis acid sites on the surface due to the strong interaction of Pb and Zr, and thus exhibited higher catalytic activity than those prepared by other processes. Graphical abstract Image 1 Highlights • Preparation process exerts significant influence on structural property and catalytic performance of Pb-Zr mixed oxide. • Pb-Zr mixed oxide prepared by co-precipitation is more active. • Well-dispersed PbO and large specific surface area are formed on Pb-Zr catalyst prepared by co-precipitation. • This work provides an effective technology for Pb-Zr catalyst preparation to transform MPC into DPC. [ABSTRACT FROM AUTHOR]

Review: 89 refs. [ABSTRACT FROM AUTHOR]

Fitness yoga is now a popular form of national fitness and sportive physical therapy. At present, Microsoft Kinect, a depth sensor, and other applications are widely used to monitor and guide yoga performance, but they are inconvenient to use and still a little expensive. To solve these problems, we propose spatial–temporal self-attention enhanced graph convolutional networks (STSAE-GCNs) that can analyze RGB yoga video data captured by cameras or smartphones. In the STSAE-GCN, we build a spatial–temporal self-attention module (STSAM), which can effectively enhance the spatial–temporal expression ability of the model and improve the performance of the proposed model. The STSAM has the characteristics of plug-and-play so that it can be applied in other skeleton-based action recognition methods and improve their performance. To prove the effectiveness of the proposed model in recognizing fitness yoga actions, we collected 960 fitness yoga action video clips in 10 action classes and built the dataset Yoga10. The recognition accuracy of the model on Yoga10 achieves 93.83%, outperforming the state-of-the-art methods, which proves that this model can better recognize fitness yoga actions and help students learn fitness yoga independently. [ABSTRACT FROM AUTHOR]

The mutant strains of COVID-19 caused a global explosion of infections, including many cities of China. In 2020, a hybrid AI model was proposed by Zheng et al., which accurately predicted the epidemic in Wuhan. As the main part of the hybrid AI model, ISI method makes two important assumptions to avoid over-fitting. However, the assumptions cannot be effectively applied to new mutant strains. In this paper, a more general method, named the multi-weight susceptible-infected model (MSI) is proposed to predict COVID-19 in Chinese Mainland. First, a Gaussian pre-processing method is proposed to solve the problem of data fluctuation based on the quantity consistency of cumulative infection number and the trend consistency of daily infection number. Then, we improve the model from two aspects: changing the grouped multi-parameter strategy to the multi-weight strategy, and removing the restriction of weight distribution of viral infectivity. Experiments on the outbreaks in many places in China from the end of 2021 to May 2022 show that, in China, an individual infected by Delta or Omicron strains of SARS-CoV-2 can infect others within 3–4 days after he/she got infected. Especially, the proposed method effectively predicts the trend of the epidemics in Xi'an, Tianjin, Henan, and Shanghai from December 2021 to May 2022. [ABSTRACT FROM AUTHOR]