The ionic parachor and predicting properties of amino acid ionic liquid homologues of 1-alkyl-3-methylimidazolium glycine

The amino acid ionic liquids(AAILs) [C3mim][Gly](1-propyl-3-methylimidazolium glycine) and [C4mim][Gly](1-butyl-3methylimidazolium glycine) have been prepared by the neutralization method and characterized by 1 H NMR spectroscopy and differential scanning calorimetry(DSC).The values of their density,surface tension and refractive index were measured at(298.15 ± 0.05) K.Since the AAILs can form strong hydrogen bonds with water,small amounts of water are difficult to remove from the AAILs by common methods.In order to eliminate the effect of the impurity water,the standard addition method(SAM) was applied to these measurements.A new concept which is called the ionic parachor has been put forward.The [C n mim] + cations were treated as a group of reference ions and the individual values of their ionic parachor were evaluated in terms of an extrathermodynamic assumption.Then,using the values of the ionic parachor of reference ions,the parachor,surface tension γ and refractive index n D of the ionic liquids investigated in this work were estimated.The estimated values correlate quite well with the corresponding experimental values.     

Preparation, characterization and adhesive properties of di- and tri-hydroxy benzoyl chitosan nanoparticles

Modified chitosans with 3,4-di-hydroxy benzoyl groups (CS-DHBA) and 3,4,5-tri-hydroxy benzoyl groups (CS-THBA) were synthesized and their nanoparticles were prepared via ionic crosslinking by tripolyphosphate (TPP). The chemical structure and degree of substitution (DS) of di-and tri-hydroxy benzoyl chitosans are determined by FTIR and 1H-NMR spectroscopy. The morphology of particles, size distribution and zeta potential of nanoparticles were studied using transmission electron microscopy (TEM) and dynamic light scattering (DLS), respectively. The mean diameters of particles of CS-DHBA and CS-THBA nanoparticles were 144 nm and 112 nm, respectively. It was found that the particles size decreased slightly with decreasing the degree of substitution and increasing degree of deacetylation (DD), due to increasing of ionic crosslinking of ammonium ions and polyanions of tripolyphosphate. The TEM photographs of CS-DHBA show that these particles are spherical in shape, but the particles of CS-THBA show some aggregation. In addition, the solubility and the mechanical properties of the prepared modified chitosans and their nanoparticles were evaluated for bio-adhesive and biomedical application. The results of solubility tests indicated that, the CS-DHBA and CS-THBA have higher solubility at pH > 7 comparing to CS. Also the CS-DHBA, CS-THBA and their nanoparticles showed a significant adhesive capacity and enhanced tensile strength and tensile modulus.     

Dispersion state of CuO on CeO_2——An incorporation model for the interaction between metal oxide and oxide support

XRD and XPS are used to study the dispersion state of CuO on ceria surface.The dispersion capacity values of CuO measured by the two methods are consistent,which are of 1.20 mmol CuO/100 m CeO2.In addition,the results reveal that highly dispersed Cu2 + ions are formed at low CuO loadings and that increasing the CuO content to a value higher than its dispersion capacity produces crystalline CuO after the surface vacant sites on CeO2 are filled.The atomic composition of the outermost layer of the CuO/CeO2 samples has been probed by using static secondary ion mass spectroscopy (SSIMS),and the ratios of Cu/Ce are found to be 0.93 and 0.46 for the 1.22 and 0 61 mmol CuO/CeO2 samples respectively.Temperature-programmed reduction (TPR) profile with two reduction peaks at 156 and 16513 suggests that the reduction of highly dispersed Cu2+ ions consists of two steps and is easier than that of CuO crystallites,in which the TPR profile has only one reduction peak at about 249℃.The above experimental results are in     

Extraction mechanism of rare earths from chloride acidic solution with ammonium-bifunctionalized ionic liquid extractants

A series of ammonium-bifunctionalized ionic liquid extractants(ammonium-Bif-ILEs) combined with a number of anions, including carboxylic acids and 1,3-diketonates, have been prepared and studied in this report. Their extraction behavior and properties toward rare earth ions(REs(Ⅲ)) are systematically investigated in chloride media as a function of important parameters such as aqueous phase p H, salting-out agent concentrations, and extraction temperature. The separation performance of ammonium-Bif-ILEs toward REs(Ⅲ) are systematically discussed. The results demonstrate that ammonium-Bif-ILEs have a synergistic effect between the cation and anions in separation of REs(Ⅲ). The influences of different anions on separation factor(b) values are further studied. By comparison, ammonium-Bif-ILEs containing 1,3-diketonates have more potential applications in La(Ⅲ)/RE(Ⅲ) separation than those containing carboxylic acids.     

Complexation of radionuclide ~(152+154)Eu(Ⅲ) with alumina-bound fulvic acid studied by batch and time-resolved laser fluorescence spectroscopy

To contribute to the understanding of Eu(Ⅲ)interaction properties on hydrous alumina particles in the absence and presence of fulvic acid(FA),the complexation properties of Eu(Ⅲ)with hydrous alumina,FA and FA-alumina hybrids are studied by batch and time-resolved laser fluorescence spectroscopy(TRLFS)techniques.The continuous increase in the fluorescence lifetime of Eu-alumina and Eu-FA with increasing pH indicates that the complexation is accompanied by decreasing number of hydration water in the first coordination sphere of Eu(Ⅲ).Eu(Ⅲ)is adsorbed onto alumina particles as outer-sphere surface complexes of≡(Al-O)-Eu·(OH)·7H_2O and≡(Al-O)-Eu·6H_2O at low pH values,and as inner-sphere surface complexes as≡(Al-O)_2-Eu~+·4H_2O at high pH.In FA solution,Eu(Ⅲ)forms complexes with FA as(COO)_2Eu~+(H_2O)_x and the hydration water number in the first coordination sphere decreases with pH increasing.The formation of≡COO-Eu-(O-Al≡)·4H_2O is observed on FA-alumina hybrids,suggesting the formation of strong inner-sphere surface complexes in the presence of FA.The surface complexes are also characterized by their emission spectra[the ratio of emission intensities of~5D_0→~7F_1(λ=594nm)and~5D_0→~7F_2(λ=619nm)transitions]and their fluorescence lifetime.The findings is important to understand the contribution of FA in the complexation properties of Eu(Ⅲ)on FA-alumina hybrids that the clarification of the environmental behavior of humic substances is necessary to understand fully the behavior of Eu(Ⅲ),or its analogue trivalent lanthanide and actinide ions in natural environment.     

Purification and Characterization of PRL Protein Tyrosine Phosphatases

PRLs constitute a subfamily of protein tyrosine phosphatases(PTPs). In the present paper are reported the molecular cloning, expression, purification, and characterization of all the three members of the PRL enzymes in human and the only PRL in C. elegans. These enzymes were expressed as glutathione S-transferase (GST) fusion proteins in DE3pLysS E. coil cells, and the recombinant fusion proteins were purified on glutathione-Sepharose affinity columns. Having been cleaved with thrombin, GST-free enzymes were further purified on an S-100 Sepharose gel filtration column. The purified proteins show single polypeptide bands on SDS-polyacrylamide gel electrophoresis. With para-nitrophenyl phosphate(p-NPP) as a substrate, PRLs exhibit classical Michaelis-Menten kinetics with Vmax values two orders of magnitude smaller than those of classic PTPs. The responses of PRLs to ionic strength, metal ions and phosphatase inhibitors are similar to those of other characterized PTPs, but their optimal pH values are different. These data thus reveal distinct common biochemical properties of PRL subfamily PTPs as well.     

Sorption characteristics and mechanisms of organic contaminant to carbonaceous biosorbents in aqueous solution

A series of carbonaceous biosorbents was prepared by pyrolyzing pine needles,a model biomass,at various temperatures (100-700℃) under an oxygen-limited condition for 6h. The elemental composi-tions and the specific surface areas (BET-N2) of the biosorbents were analyzed. Sorption properties of 4-nitrotoluene to the biosorbents and their mechanisms were investigated,and then correlated with the structures of the biosorbents. The result shows that with the increase of the pyrolytic temperature,the aromaticity of the carbonaceous biosorbents increases dramatically and the polarity (the (N O)/C atomic ratio) decreases sharply. Correspondingly,conformations of the organic matter in the biosor-bents transform gradually from a "soft-state" to a "hard-state" and the specific surface areas of the resultant biosorbents extend rapidly. The sorption isotherms fit well with the Freundlich equation. The regression parameters (i.e.,N and lgKf) are linearly related to the aromaticity indices (the H/C atomic ratio). Contributions of adsorption and partition to total sorption of the carbonaceous biosorbents are quantified. The adsorption of the carbonaceous biosorbents increases quickly with the increase of the pyrolytic temperature. The saturated adsorption amounts (Qmax) increase linearly with the increase of the specific surface areas (SA) of the biosorbents. For the carbonaceous biosorbents with hard-state carbon,the calculated normalized-Qmax values by SA are comparable to the theoretical estimation (2.45 μmol/m2). In comparison,for the carbonaceous sorbents with soft-state carbon,the calculated nor-malized-Qmax values by SA are much higher than the theoretical estimation. The partition coefficients (Kom) increase with the decrease of the polarity of the biosorbents,reaching a maximum,and then de-crease sharply with further decreasing the polarity,suggesting that partition mechanism be dominated by the compatibility and accessibility of the sorbent medium with organic pollutant. These observations will provide a theoretical and practical reference to design a cost-effective and high-efficient sorbent,and to accurately predict sorption properties and mechanisms of a given sorbent.     

Hartree-Fock-Roothaan Calculations for Ground States of Some Atoms Using Minimal Basis Sets of Integer and Noninteger n-STOs

Hartree-Fock-Roothaan (HFR) calculations for ground states of some atoms, i.e. He, Be, Ne, Ar, and Kr have been performed using minimal basis sets of Slater type orbitals (STOs) with integer and noninteger principal quantum numbers (integer n-STOs and noninteger n-STOs). The obtained total energies for these atoms using minimal basis sets of integer n-STOs are in good agreement with those in the previous literature. On the other hand, for the case of minimal basis sets of noninteger n-STOs, although the calculated total energies of these atoms agree well with the results in literature, some striking results have been obtained for atoms Ar and Kr. Our computational resuits for the energies of atoms Ar and Kr are slightly better than those in literature, by amount of 0.00222 and 0.000054 a.u., respectively. The improvement in the energies of atoms Ar and Kr may result from the efficient calculations of one-center two-electron integrals over noninteger n-STOs. For some atomic ions in their ground state, HFR calculations have been carried out using minimal basis sets of noninteger n-STOs. The obtained total energies for these atomic ions are substantially lower than those available in literature.     

Enthalpic Interaction for α-Amino Acid with Alkali Metal Halides in Water

The studies of the enthalpic interaction parameters, hxy, hxyy and hxxy, of alkali metal halides with glycine, α-alanine and α-aminobutyric acid were published. Synthetic considering of the results of the studies, some interesting behaviors of the interaction between alkali metal halides and the α-amino acids have been found. The values of hxy will increase with the increase of the number of carbon atoms in alkyl side chain of amino acid molecules and decrease with the increase of the radius of the ions. The increasing of the salt‘s effect on the hydrophobic hydration structure as the radii of anion is more obvious than as that of cation. The value of hxxy will regularly decrease with the increase of the number of carbon atoms in the alkyl chain of amino acids and linear increase with the increase of the radius. But the relation of hxxyWith the radius of cations is not evident. The value of hxyywill increase with the increase of the radii of the ions. As the increase of the number of carbon atoms of amino acids, hxyy is decreas for the ions which have lager size and there is a maximum value at α-alanine for the ions which have small size. The behaviors of the interaction mentioned above were further discussed in view of electrostatic and structural interactions.     

Theoretical Studies on the Molecular Structures and Thermodynamic Properties of Polychlorinated Fluoranthenes

DFT-B3LYP/6-311G** method has been used to optimize molecular geometric structures of 527 polychlorinated fluoranthene(PCFRT) congeners and calculate their thermo-dynamic properties in the ideal gas state,such as heat capacity at constant volume(Cv),entropy(S),standard enthalpy of formation(ΔfH) and standard Gibbs free energy of formation(ΔfG).The relations of Cv,S,ΔfH and ΔfG with the number and position of chlorine atoms have also been explored,from which the relative stability of PCFRT congeners was theoretically proposed according to the magnitude of the relative standard Gibbs free energy of formation(Δr,fG).It was found that some of the PCFRT isomers are in a nonplanar configuration and there are intramolecular Cl…Cl weak interactions in some of the isomers.With increasing the number of chlorine atoms,the values of ΔfH and ΔfG of the most stable PCFRT isomers decrease initially and then increase.The values of ΔfH and ΔfG of PCFRT congeners with the same number of chlorine atoms show a strong dependence on the positions of chlorine atoms.The relative thermodynamic stability of PCFRT isomers is determined mainly by intramolecular adjacent Cl…Cl nuclear repulsive interaction between Cl atoms at two different six-membered rings.Most PCFRT congeners are easier to form thermodynamically than their parent compound.     

X-RAY STUDIES ON THE STRUCTURE OF DES-PENTAPEPTIDE INSULIN AT 2.4 RESOLUTION——THE DPI MOLECULE AND ITS STRUCTURAL RELATIONSHIP WITH INSULIN

The structure of the monomeric insulin analogue des(B26—B30) insulin is presented.; A detailed comparison with the 2Zn insulin structures shows that while there are some large changes in the structure, the basic secondary structural units maintain their integrity. The DPI structure is broadly similar to molecule Ⅰ in the 2Zn structure, and in this respect is like other crystal forms of insulin. In addition to changes on the surface of the structure there are some subtle but extensive changes in the heart of the molecule. The molecules are closely packed in the crystal with many and varied contacts, including a complex network of protein-cadmium interactions and a considerable number of water mediated contacts. The molecular surface has an unusually large number of hydrophobic groups which tend to cluster in a thick band running around the protein. The crystal structure is well ordered, indeed the clarity of some side chains and the definition of the water molecules is superior to that found in the mor     

Investigation on the Electrochemical Polymerization of Catechol by Means of Rotating Ring—disk Electrode

The electrolysis of catechol was studied in the pH values of 1 to 10. The results from the rotating ring-disk electrode (RRDE) experiments show that at low pH values,the electrochemical polymerization of catechol was performed by one step,and at higher pH values,the electrochemical polymerization of catechol was carried out by two steps,i.e.oxidation of catechol and followed by polymerization.The intermediates generated at the disk were detected at the ring electrode in the ring potential region of -0.2 to 0 V(vs.Ag/AgCl).One of reasons for the decrease in the ratio of ir to id with increasing the ring potential is caused by formation of positively charged intermediates at the disk electrode.This ratio increases with increasing the rotation rate of the RRDE,which indicates that the intermediates are not stable.A shielding effect during polymerization of catechol was observed when the ring potential was set at 0.1 V (vs.Ag/AgCl).The electron spin resonance(ESR) of polycatechol show that polycatechol possesses unpaired electrons.The images of polycatechol films synthesized at differentconditions are described.     

THE CRYSTAL STRUCTURE OF A NOVEL INCLUSION COMPOUND——TETRAKIS

The title compound crystallizes in the space group C_5~4 with unit cell constants a=17.900 (5)A, b=18.466 (7)A, c=15.483 (4)A, β=92.78 (2)°and contains four formulaunits of MoFeS_(10)Cl_4N_4C_(34)H_(54). Intensities of 3499 independent reflections are collected withdiffractometer using MoKa radiation. The y coordinates of the Mo atoms are derived fromthe Patterson function. The parameters of the other atoms are found from successive Fourierand difference syntheses. The block-diagonal least-squares refinement for all atoms gives a final discrepancy factorR = 0.054. The result of structure analysis shows that this inclusion compound consists of threekinds of structural units and the oppositely charged complex ions [Mo(S_2CN(Et)_2)_4]~ and[FeCl_4]~- form a very interesting ionic host framework with infinite tunnels extending alongC direction and containing guest disulfide molecules PhCH_2SSCH_2Ph.     

Effect of inorganic positive ions on the adsorption of surfactant Triton X-100 at quartz/solution interface

The electrode-separated piezoelectric sensor (ESPS), an improved setup of quartz crystal microbalance (QCM), has been employed to investigate the adsorption behavior of nonionic surfactant Triton X-100 at the hydrophilic quartz-solution interface in mineralized water medium in situ, which contained CaCl2 0.01 mol·L?1, MgCl2 0.01 mol·L?1, NaCl 0.35 mol·L?1. In a large scale of surfactant concentration, the effects of Ca2 , Mg2 and Na on the adsorption isotherm and kinetics are obviously different. In aque-ous solution containing NaCl only, adsorption of Triton X-100 on quartz-solution interface is promoted, both adsorption rate and adsorption amount increase. While in mineralized water medium, multivalent positive ions Ca2 and Mg2 are firmly adsorbed on quartz-solution interface, result in the increasing of adsorption rate and adsorption amount at low concentration of surfactant and the peculiar desorption of surfactant at high concentration of Triton X-100. The results got by solution depletion method are in good agreement with which obtained by ESPS. The "bridge" and "separate" effect of inorganic positive ions on the adsorption and desorption mechanism of Triton X-100 at the quartz- solution interface is discussed with molecular dynamics simulations (MD), flame atomic absorption spectrometry (FAAS) and atomic force microscopy (AFM) methods.     

Preparation and characterization of pva based solid polymer electrolytes for electrochemical cell applications

Solid polymer electrolyte films containing poly(vinyl alcohol) (PVA) and magnesium nitrate (Mg(NO3)2) were prepared by solution casting technique and characterized by using XRD, FTIR, DSC and AC impedance spectroscopic analysis. The amorphous nature of the polymer electrolyte films has been confirmed by XRD. The complex formation between PVA and Mg salt has been confirmed by FTIR. The glass transition temperature decreases with increasing the Mg salt concentration. The AC impedance studies are performed to evaluate the ionic conductivity of the polymer electrolyte films in the range of 303 383 K, and the temperature dependence seems to obey the Arrhenius behavior. Transport number measurements show that the charge transport is mainly due to ions. Electrochemical cell of configuration Mg/(PVA + Mg(NO3)2) (70:30)/(I2 + C + electrolyte) has been fabricated. The discharge characteristics of the cell were studied for a constant load of 100 kΩ.     

Defect-induced Surface and Interface Reconstruction in Novel Two-dimensional Materials Revealed by Low Voltage Scanning Transmission Electron Microscopy

Two-dimensional(2 D) materials attracted substantial attention due to their extraordinary physical properties resulting from the unique atomic thickness. 2 D materials could be considered as material systems with flat surfaces at both sides, while the van der Waals gap is a natural out-of-plane interface between two monolayers. However, defects are inevitably presented and often cause significant surface and interface reconstruction, which modify the physical properties of the materials being investigated. In this review article, we reviewed the effort achieved in probing the defect structures and the reconstruction of surface and interface in novel 2 D materials through aberration corrected low voltage scanning transmission electron microscopy(LVSTEM). The LVSTEM technique enables us to unveil the intrinsic atomic structure of defects atom-by-atom, and even directly visualize the dynamical reconstruction process with single atom precision. The effort in understanding the defect structures and their contributions in the surface and interface reconstructions in 2 D materials shed light on the origin of their novel physical phenomenon, and also pave the way for defect engineering in future potential applications.     

The preparation of supported ionic liquids (SILs) and their application in rare metals separation

This review summarizes the preparation methods of support ionic liquids (SILs) and their applications in rare metals separation. The rare metals separation includes the recovery of high value metal ions and the removal of heavy metal ions from wastewater. SILs can be used as a kind of highly efficient multifunctional separation materials. The preparation methods of SILs include chemical immobilization technique in which ILs moieties are supported on solid supports via covalent bonds and physical immobilization techniques in which ILs are immobilized on solid supports via physical method such as simple im- pregnation, sol-gel method. According to the difference of solid supports, this review summarizes the application of polymer supported ionic liquids (P-SILs), silica based material supported ionic liquids (SM-SILs) and membrane supported ionic liq- uids (M-SILs) in rare metals separation. P-SILs and SM-SILs prepared by chemical method with N-methylimidazolium group can be used as highly efficient anion exchangers with high thermal stability and good chemical stability for adsorption of Cr(VI), Re(VII), Ce(IV). P-SILs prepared via simple impregnation afforded IL functionalized solvent impregnated resins (SIRs) which showed high separation efficiency and selectivity in the separation of rare earths(III) (REs(III)). SM-SILs prepared via sol-gel method with IL doped in the support as porogens or extractant show high removal efficiencies and excellent stability for the separation of RE(III), Cr(III) and Cr(VI). M-SILs with IL as plasticizer or carrier show improved stability, high perme- ability coefficient and good selectivity for Cr(VI) transport. Different supports and different supporting methods were suffi- ciently compared. Based on the different practical application, different forms of SILs can be prepared for separation of rare metals with high separation efficiency and selectivity.     

PRELIMINARY STUDY ON MECHANISM OF PLANT ROOTS TO INCREASE SOIL ANTISCOURIBILITY ON THE LOESS PLATEAU

The effects of the root system of trees, shrubs and grasses on the hydraulic andphysical properties of soil and their interrelation with increasing soil anti--scouribility byroots are quantitatively demonstrated in this paper for the first time. Based on the analysisof the leading factors of roots to increase the soil anti--scouribility, a mathematical modelon increasing soil anti-scouribility by roots is established. The value in application of themodel is to explain the mechanism of roots to increase the soil anti-scouribility and toevaluate the increasing effects of soil anti-scouribility by roots in different layers of soilThe calculated results of the values in soil anti--scouribility intensified by roots at variousintensities of rainfall and slopes of the model have higher precision, all of the meanmaximum deviations between the estimated and observed values being less than 1.417 s/g.     

Molecular structure of [(trien)Zn(im)Zn(trien)](ClO_4)_3 complex and ESR spectra of its single-crystal doped with [(trien)Cu(im)Zn(trien)l(ClO_4)_3 complex

The crystal structure of the title complex was measured, in which the two zinc atoms with coordination polyhedron of distorted tetragonal pyramid (TP) are bridged by an imidazolate in the apical position of the TP forming a dimer. The isomorphous [(trien)Cu(im)Zn(trien)](ClO4)3·H2O complex was doped in the title complex and the recorded single-crystal ESR spectra by fitting gave two sets of the principal values of g and A tensors, which were assigned to the physically distinct sites of the two magnetically equivalent molecules in the unit cell. Lattice distortion at the Cu(II) ion sites and the bonding parameters of Cu(II) ions are further calculated, and the bonding nature of Cu(II) ions is discussed.     

Quantitative prediction of substituted products based on quantum-chemical parameters and neural network method

The criterion of orientating group of electrophilic aromatic nitration was discussed by means of pattern recognition method with quantum-chemical parameters as features, and the product ratios of the reactions were quantitatively calculated using artificial neural network (ANN) method with the same parameters as inputs, based on the ab initio calculation of quantum chemistry. The quantum-chemical parameters involved orbital energy, orbital electron population, atomic total electron density and atomic net charge. The predicted values are in agreement with experimental results and (he predicted error of the ANN with quantum-chemical parameters for the reaction is the smallest among the all methods.