羧化聚苯醚与聚苯乙烯共混体系相分离初期分子量影响的光散射研究

 本文用激光光散射方法研究了具有特殊相行为[(低临界溶解温度(LCST),高临界溶解温度(UCST)共存]共混体系羧化聚苯醚和聚苯乙烯在UCST域内的不稳相分离初期分子量对动力学参数的影响。结果表明:相分离初期动力学过程与Cahn理论吻合;随着分子量增加,表现扩散系数D_app明显减小;该体系的表现扩散系数为10^-14 cm²s^-1数量级。deGennes管子模型可很好地描述不稳相分离初期大分子扩散行为。     

Numerical simulation of voltammetry focusing on the effect of initial concentration of products in reversible systems with complex stoichiometry

The effect of initial concentration of products in a general reaction of reversible process with complex stoichiometry expressed as mO + ne^? ai qR was evaluated using numerical simulations with various complex stoichiometric coefficients m and q of oxidized (O) and reduced (R) species, respectively, and with various initial concentrations. In the simulations, the transform of voltammograms according to changes in the initial concentrations were characterized by the parameter ??? (= c ₀*(D _O)^1/2/c _R* (D _R)^1/2) for any stoichiometric system. Based on the simulation results, empirical relations were obtained for (1) peak potential involving parameters for stoichiometry (m and q) and for the initial conditions (???), and (2) peak current.     

The effect of pressure and temperature of self-diffusion coefficients in several concentrated deuterium oxide diamagnetic electrolyte solutions

The pressure dependences of the self-diffusion coefficients of deuterium oxide in 4.5m solutions of LiCl–D₂O and CsCl–D₂O (also 7m) and 3.06m CaCl₂–D₂O have been measured by the NMR spin-echo method at 30°C, 60°C, and 90°C. Shear viscosities and densities of these solutions have also been determined over the same range of experimental conditions. The experimental data show that the diffusion constantD decreases with the increasing structure-making ability of the electrolyte cation Ca⁺²>Li⁺. In contrast, the diffusion coefficient for D₂O in the 4.5 and 7m CsCl solutions is equal to that for pure D₂O at 30°C but lower at 60°C and 90°C. It has been found that the Stokes-Einstein equation relates well the diffusion coefficients to shear viscosity in these concentrated electrolyte solutions.     

Stereoselective Inclusion and Structure of Equatorial-trans-1,2-dichlorocyclohexane

Abstract

Optically active (R,R)-(-)-trans-1,2-dichlorocyclohexane (DCC) was isolated as an inclusion crystal with the optically active host, (R,R)-(-)-trans-2,3-(hydroxydiphenylmethyl)-1,4-dioxaspiro[4.4]-nonane, and the structure of the 2:1 inclusion crystal has been determined by X-ray analysis. Crystal data: C₇₂H₇₄O₈Cl₂, orthorhombic, P2₁2₁2 (No. 18), a = 17.465(6) Å, b = 20.095(6) Å, c = 8.664(5) Å, V = 3040(2) ų, Z = 2, D_c = 1.24g cm^?3, D_m = 1.23g cm^?3, T = 293 K and final R ₁ = 0.050 for 2766 observed data (I > 2σ(I)). The conformation of DCC in the inclusion crystal has been found to be equatorial and the absolute configuration was definitely determined to be (R,R) on the basis of the known configuration of the host.     

Thermodynamics of ionization of D2O and D2PO 4 −

The quotients for the ionization of D₂O and the neutralization of D₂PO ₄ ^– have been determined potentiometrically in 0.2m KCl from 50 to 300°C at the saturation pressure. By combination with the other data, analytical expressions for the dependence on temperature and ionic strength have been derived. Rounded values for the thermodynamic quantities for the ionization of D₂O and the neutralization of D₂PO ₄ ^– are given along with standard errors. The magnitude of the isotope effects is discussed in terms of the zero-point-energy approximation and the acid strength in light water.ORAU Summer Trainee Program 1973.     

Length scale hierarchy in sol,gel, and coacervate phases of gelatin

Length scale hierarchy in gelatin sol, gel, and coacervate (induced by ethanol) phases, having same concentration of gelatin in aqueous medium (13% w/v), has been investigated through small angle neutron scattering and rheology measurements. The static structure factor profile, I(q) versus wave vector q, was found to be remarkably similar for all these samples. This data could be split into three distinct q‐regimes: the low‐q regime, I_ex(q) = I_ex(0)/(1+q²ζ²)² valid for q < 3R_g^?1; the intermediate q‐regime, I(q) = I(0)/(1+q²ξ²) for 3R_g^?1 < q < ξ^?1; and the asymptotic regime, I(q) = (c/q) exp(?R_c²q²/2) for q > ξ^?1. Consequently, three distinct length scales could be deduced from structure factor data: (a) inhomogeneity of size, ζ = 20 ± 1 nm for all the three phases; (b) average mesh size, ξ₀ = 2.6 ± 0.2 nm for sol and gel, and smaller mesh size, ξ_os = 1.2 ± 0.2 nm for coacervate; and (c) cross section of gelatin chains, R_c = 0.35 ± 0.04 nm. In addition, the structure factor data obtained from coacervating solution analyzed in the Guinier region, I(q) = exp(?q²R_g²/3), yielded value of typical radius of gyration of clusters, R_g ≈ 69 nm that indicated existence of triple‐helices of length, L ≈ 239 nm; (d) Frequency and temperature sweep measurements conducted on coacervate samples revealed two other length scales: (e) viscoelastic length, ξ_ve = 14 ± 2 nm and (f) correlation length at melting, ξ_T = 500 ± 70 nm. Thus, existence of six distinct length scales, (a–f), ranging from 1.2 to 500 nm has been established in the coacervate phase of gelatin–ethanol–water system. Results are discussed within the framework of Landau‐Ginzburg treatment of dynamically asymmetric systems (Prog Theor Phys 1977, 57, 826; Phys Rev A 1991, 44, R817; J Phys II (France) 1992, 2, 1631). © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1653–1667, 2006     

Crystallization kinetics of syndiotactic polypropylene

Melting-point and spherulite growth rate measurements for a sample of syndiotactic polypropylene (S = 0.716 and η = 0.356) were analyzed for the parameters characterizing crystal formation and growth: T_m = 159 ± 2°C, σ_e = 47 erg cm ^?2, σ = 4.4 erg cm^?2, and q = 5.6 kcal per mole of folds. The q and σ_e values place syndiotactic polypropylene in the group of “unhindered” polymers. Failure of the isotactic-polypropylene spherulite growth rate data to follow current theories of crystal growth precluded a comparison of crystal parameters of the two stereoisomers. At comparable degrees of supercooling, the absolute growth rates for the two forms are of the same order of magnitude and exhibit one or more crossover(s) in relative position.     

Isotope exchange of strontium and molybdate ions in strontium polymolybdates

The heterogeneous isotopic exchange reactions in strontium polymolybdates of Sr²⁺ and MoO₄ ^2- ions in the strontium nitrate and sodium molybdate solutions have been studied using ⁹⁰Sr and ⁹⁹Mo as tracers. Electrometric methods have been used to study the compositions of strontium molybdates obtained by adding strontium chloride to a progressively acidified solution of sodium molybdate. It has been found that the exchange fraction increases with increasing chain length of strontium polymolybdate. The exchange equilibrium constant (K _ex) has been calculated between 298 and 348 K as well as DG°, DH° and DS°. The results indicate that Sr²⁺ cations have a much higher affinity for exchangers than MoO₄ ^2- anions. By fitting the data to the Dubinin-Radushkevich (D-R) isotherm it has been shown that the exchange capacity (X _m ) for both ions is affected by the ion adsorption process at low temperatures and by the ion exchange process at high temperatures. At high concentrations, the recrystallization process contributes to on the cation exchange but is ineffective on the anion exchange mechanism.     

Study of the Crystal Structure of Oxo‐bridged Binuclear FeIII Complex with Chiral Salen Ligand

A oxo‐bridged binuclear iron complex with chiral salen ligand [Fe₂L₂]O (H₂L = R, R'‐N, N'‐bis (3,5‐di‐tert‐butylsalicylaldene)‐1, 2‐cyclohexanediamine) has been synthesized and the structure has been determined by X‐ray diffraction analysis. The title complex crystallizes in triclinic system with space group P‐1. Crystal data: a = 1.42555(14) nm, b = 1.54889 (15) nm, c = 1.83662 (17) run, = 103.873(2)°, β = 100.506(2)°, 7=101.840(2)°, V = 3.7371 nm³, D_c = 1.082 g/cm³ and Z = 2. In the complex, each iron center is penta‐coordination and in distorted square‐pyramidal environment. Two Fe^m atoms are intramolecularity bridged by an oxygen atom with Fe‐Fe nonbond distance of 0.3517(3) nm.     

Diffusing probe measurements in Newtonian and elastic solutions

The diffusion coefficients of polystyrene latex spheres and hematite particles in both Newtonian and elastic liquids have been measured using dynamic light scattering. The diffusion coefficients of the latex particles measured in glycerol/water (Newtonian) solutions obey Stokes–Einstein behaviour over a range of solvent viscosities and temperatures. Two apparent diffusion coefficients for the particles are measured in visco-elastic polyacrylamide and polyacrylate solutions and are designated D_fast and D_slow. The apparent fast diffusion coefficients measured in the elastic solutions show an increase to a maximum, above that measured in the solvent water, with increasing polyelectrolyte concentration. At higher polyelectrolyte concentrations the observed D_fast values decrease below the value obtained in the solvent water. D_fast increases with the scattering vector squared (q²) while D_slow, is independent of q².     

Influence of dry density on HTO diffusion in GMZ bentonite

With the low permeability and high swelling property, Gaomiaozi (GMZ) bentonite is regarded as the favorable candidate backfilling material for a potential repository. The diffusion behaviors of HTO in GMZ bentonite were studied to obtain effective diffusion coefficient (D _e) and accessible porosity (ε) by through- and out-diffusion experiments. A computer code named Fitting for diffusion coefficient (FDP) was used for the experimental data processing and theoretical modeling. The D _e and ε values were (5.2–11.2) × 10⁻¹¹ m²/s and 0.35–0.50 at dry density from 1,800 to 2,000 kg/m³, respectively. The D _e values at 1,800 kg/m³ was a little higher than that of at 2,000 kg/m³, whereas the D _e value at 1,600 kg/m³ was significantly higher (approximately twice) than that of at 1,800 and 2,000 kg/m³. It may be explained that the diffusion of HTO mainly occurred in the interlayer space for the highly compacted clay (dry density exceeding 1,300 kg/m³). 1,800 and 2,000 kg/m³ probably had similar interlayer space, whereas 1,600 kg/m³ had more. Both D _e and ε values decreased with increasing dry density. For compacted bentonite, the relationship of D _e and ε could be described by Archie’s law with exponent n = 4.5 ± 1.0.     

The crystal structure of tetraphenylphosphonium tetracyanohydroxooxorhenium(V)

Summary The crystal structure of (PPh₄)₂[ReO(OH)(CN)₄]·5H₂O has been determined from three-dimensional x-ray diffraction data. The light brown crystals are monoclinic, space group P2₁/n, with cell dimensionsa=16.753(2),b=19.928(2),c=15.338(2) Å and =101,894(1)°,z=4, D_m=1.45(1) g cm^–3. The anisotropic refinement of the 6088 observed reflections converged to R=0.077.The [ReO(OH)(CN)₄]^2– ion has a distorted octahedral geometry. Bond distances: Re =1.70(1), Re–OH=1.90(1) and ReC_av=2.12(2) Å. The Re atom is displaced by 0.08 Å out of the plane formed by the four carbon atoms towards the terminal oxo ligand.     

Synthesis and properties of new polymeric surfactant with quaternary ammonium salt

The polymeric surfactant with quaternary ammonium salt (PQ) was synthesized by cationic ring-open polymerization using boron trifluoride diethyletherate as cationic catalyst. The chemical structure and aggregation behavior of PQ were studied by ¹H NMR, surface tension, static light scattering, dynamic laser light scattering, electrical conductivity, and fluorescence measurement. The results show the surface tension (γ_cmc) and critical micelle concentration (cmc) of PQ decrease with increasing of sodium chloride concentration. The cmc and γ_cmc values of PQ measured by electrical conductivity and fluorescence measurements mainly identify with that obtained by surface tension measurements. The thermodynamic parameters (DG_m⁰ \Delta G_m^0 ,DH_m⁰ \Delta H_m^0 ,DS_m⁰ \Delta S_m^0 ) from electrical conductivity indicated that the micellization of PQ was mainly the process of entropy-driven. In addition, the results from the viscosity stability between hydrolyzed polyacrylamide (HPAM) and PQ showed that the viscosities of mixed system for HPAM and PQ are higher than the viscosity of HPAM.     

Transition Metal Halide Salts and Complexes of 2-Aminopyrimidine: Cobalt(II) and Nickel(II) compounds,Crystal Structures of Bis(2-Aminopyrimidinium)MX4 [M = Co,Ni; X = Cl,Br] and 2-Aminopyrimidinium(+2) [NiBr2(H2O)4]Br2

The reaction of MX₂ (M = Co(II), Ni(II); X = Cl, Br) with 2-aminopyrimidine in aqueous acid yields compounds [(2-apmH)₂MX₄], (2-apmH)₂[MX₄], or (2-apmH₂) [MX₂(H₂O)₄]X₂ (2-apmH = 2-aminopyrimidinium; 2-apmH₂ = 2-aminopyrimidinium(2+)). All compounds have been characterized by single crystal X-ray diffraction. The compounds [(2-apmH)₂MX₄] with M = Co, X = Cl (1); M = Ni, X = Cl (3); and M = Ni, X = Br (4) are isomorphous and crystallize as nearly square planar MX₄ units with the 2-apmH cations coordinated in the axial sites through the unprotonated ring nitrogen. (2-ApmH)₂[CoBr₄] (2) crystallizes as the salt with a nearly tetrahedral CuBr₄ ^2- anion. (2-ApmH₂)[NiBr₂(H₂O)₄]Br₂ (5) forms as a cocrystal of the neutral, six-coordinate nickel complex and (2-ampH₂)Br₂, stabilized by extensive hydrogen bonding. Crystal data (1): monoclinic, P2₁/c, a = 7.540(4), b = 12.954(4), c = 7.277(3) Å, β = 110.09(6), V = 667.4(5) ų, Z = 2, D_calc = 1.955 Mg/m³, μ = 2.079 mm^-1, R = 0.0501 for [|I|≥2(I)]. For (2): triclinic, P-1, a = 7.720(2), b = 7.916(2), c = 14.797(3) Å, α = 97.264(3), β = 104.788(3), γ = 105.171(3)°, V = 825.3(3) ų, Z = 2, D_calc = 2.296 Mg/m³, μ = 10.715 mm^-1, R = 0.0308 for [|I|≥2(I)]. For (3): monoclinic, P2₁/c, a = 7.595(3), b = 12.891(4), c = 7.204(3) Å, β = 111.07(3)°, V = 658.2 ų, Z = 2, D_calc = 1.982 Mg/m³, μ = 2.279 mm^-1, R = 0.0552 for [|I|≥2(I)]. For (4): monoclinic, P2₁/c, a = 7.840(2), b = 13.358(4), c = 7.518(2) Å, β = 110.923(3)°, V = 938.6(3) ų, Z = 2, D_calc = 2.577 Mg/m³, μ = 12.18 mm^-1, R = 0.0280 for [|I|≥2(I)]. For (5): orthorhombic, Pnma, a = 16.776(6), b = 11.943(4), c = 7.079(3) Å, V = 1418.2(9) ų, Z = 4, D_calc = 2.564 Mg/m³, μ = 12.639 mm^-1, R = 0.0381 for [|I|≥2σ(I)].     

Effects of glucose,glutamine, and malate on the metabolism of spodoptera frugiperda clone 9 (sf9) cells

Optimal design and operation of bioreactors for insect cell culture is facilitated by functional relations providing quantitative information on cellular metabolite consumption kinetics, as well as on the specific cell growth rates (μ_G). Initial specific consumption rates of glucose, malate, and oxygen, and associated changes in μ_G, were measured forSpodoptera frugiperda clone 9 (Sf9) cells grown in batch suspension culture in medium containing 7–35 mM glucose, 0–16 mM malate, and 4–16 mM glutamine. The initial specific glucose consumption rate (q _G ) could be described by a modified Michaelis-Menten equation treating malate as a “competitive” inhibitorK ₁ = 6.5 mM) and glutamine as a “noncompetitive” inhibitorK _I = 14 mM) ofq _G , with aK _m of 7.1 mM for glucose. All three carbon sources were found to increase μ_G in a saturable manner, and a modified Monod equation was employed to describe this relationship (μ_Gmax = 0.047 h^-1). The initial specific oxygen consumption rate (q_O2) in Sf9 cells could be related to μ_G by the maintenance energy model, and it was calculated that, under typical culture conditions, about 15–20% of the cellular energy demand comes from functions not related to growth. Fitted parameters in mathematical expression for μg: K₄, Monod constant for glucose (mM); K₅, modified Monod constant for malate (mM); K₆, Monod constant for glutamine (mM); m_o2, specific consumption rate of oxygen by the cells under zero-growth conditions (nmol/cell/h); q_F, initial specific fumarate production rate (nmol/cell/ h);q _G , initial specific glucose consumption rate (nmol/cell/h); q_Gmax, maximum initial specific glucose consumption rate (nmol/cell/h);q _M , initial specific malate consumption rate (nmol/cell/h); q_o2, initial specific oxygen consumption rate (nmol/cell/h); Y_o2, cell yield on oxygen (cells/nmol); μ, initial specific cell growth rate (h^-1); μ_g, initial specific cell growth rate (h^-1); μG_max, maximum initial specific cell growth rate (h^-1).     

Formation of H3O+ from alcohols and ethers induced by intense laser fields

The processes of H₃O⁺ production from alcohols (ethanol, 2‐propanol, 1‐propanol, 2‐butanol) and ethers (diethyl ether and ethyl methyl ether), and their deuterium‐substituted species, by intense laser fields (800 nm, 100 fs, ～1 × 10¹⁴ W/cm) were investigated through time‐of‐flight (TOF) mass spectrometry. H₃O⁺ formation was observed for all these compounds except for ethyl methyl ether. From the analysis of TOF signals of H_(3?n)D_nO⁺ (n = 0, 1, 2, and 3) that have expanding tails with increasing flight time, it has been confirmed that the reaction proceeds through metastable dissociation from the intermediate species C₂H_(5?m)D_mO⁺(m = 0–5). The common shape of the H_(3?n)D_nO⁺ signal profiles contains two major distributions in the time constant, i.e., fast and slow components of <50 ns and ～500 ns, respectively. The H_(3?n)D_nO⁺ branching ratio is interpreted to be the result of complete scrambling of four hydrogen atoms at the C? C site in C₂H₄‐OH⁺, and partial exchange (18–38%) of a hydrogen atom in the OH group with four other hydrogen atoms within 1 ns prior to H_(3?n)D_nO⁺ production. Ab initio calculations for the isomers and transition states of C₂H₅O⁺ were also performed, and the observed H_(3?n)D_nO⁺ production mechanism has been discussed. In addition, a stable isomer having a complex structure and two isomerization pathways were discovered to contribute to the H₃O⁺ formation process. Copyright © 2010 John Wiley & Sons, Ltd.     

Planar Hypercoordinate Carbons in Alkali Metal Decorated CE32− and CE22− Dianions

After exploring the potential energy surfaces of M_mCE₂^p (E=S−Te, M=Li−Cs, m=2, 3 and p=m-2) and M_nCE₃^q (E=S−Te, M=Li−Cs, n=1, 2, q=n-2) combinations, we introduce 38 new global minima containing a planar hypercoordinate carbon atom (24 with a planar tetracoordinate carbon and 14 with a planar pentacoordinate carbon). These exotic clusters result from the decoration of V-shaped CE₂²⁻ and Y-shaped CE₃²⁻ dianions, respectively, with alkali counterions. All these 38 systems fulfill the geometrical and electronic criteria to be considered as true planar hypercoordinate carbon systems. Chemical bonding analyses indicate that carbon is covalently bonded to chalcogens and ionically connected to alkali metals.     

Theoretical studies of the concentration dependences of d–d transition band,g factors,and local distortion for V4+ in Li2O–PbO–B2O3–P2O5 glasses

In this work, the g factors, d–d transition band, local distortion, and their concentration dependences for impurity V⁴⁺ in 20Li₂O–20PbO–45B₂O₃–(15 − x)P₂O₅:V₂O₅ (0 ≤ x ≤ 2.5 mol%) glasses are theoretically investigated by using perturbation formulas of g factors for a tetragonally compressed octahedral 3d¹ cluster. In the light of the cubic polynomial concentration functions for cubic field parameter D_q, covalency factor N, and relative tetragonal compression ratio ρ, the calculated concentration dependences of d–d transition band and g factors for V⁴⁺ show good agreement with the experimental data. With increasing x, N (≈0.7682–0.8165) displays the monotonously increasing trend, whereas ρ (≈6.5–4.2%) and D_q (≈1504.9–1481.1 cm⁻¹) exhibit the decreasing tendencies. The above concentration dependences can be ascribed to the modifications of the V⁴⁺–O²⁻ bonding and orbital admixtures around the impurity V⁴⁺ due to the effects of V₂O₅ doping on the stability of the glass network, the strength of local crystal fields, and the electron cloud distribution.     

Thermochemical study on ternary complex of dysprosium <Emphasis Type="Italic">m</Emphasis>-nitrobenzoic acid with <Emphasis Type="Italic">o</Emphasis>-phenanthroline

A ternary binuclear complex of dysprosium chloride hexahydrate with m-nitrobenzoic acid and 1,10-phenanthroline, [Dy(m-NBA)₃phen]₂·4H₂O (m-NBA: m-nitrobenzoate; phen: 1,10-phenanthroline) was synthesized. The dissolution enthalpies of [2phen·H₂O(s)], [6m-HNBA(s)], [2DyCl₃·6H₂O(s)], and [Dy(m-NBA)₃phen]₂·4H₂O(s) in the calorimetric solvent (V_DMSO:V_MeOH = 3:2) were determined by the solution–reaction isoperibol calorimeter at 298.15 K to be \Updelta_\texts H_\textm^q \Updelta_{\text{s}} H_{\text{m}}^{\theta } [2phen·H₂O(s), 298.15 K] = 21.7367 ± 0.3150 kJ·mol⁻¹, \Updelta_\texts H_\textm^q \Updelta_{\text{s}} H_{\text{m}}^{\theta } [6m-HNBA(s), 298.15 K] = 15.3635 ± 0.2235 kJ·mol⁻¹, \Updelta_\texts H_\textm^q \Updelta_{\text{s}} H_{\text{m}}^{\theta } [2DyCl₃·6H₂O(s), 298.15 K] = −203.5331 ± 0.2200 kJ·mol⁻¹, and \Updelta_\texts H_\textm^q \Updelta_{\text{s}} H_{\text{m}}^{\theta } [[Dy(m-NBA)₃phen]₂·4H₂O(s), 298.15 K] = 53.5965 ± 0.2367 kJ·mol⁻¹, respectively. The enthalpy change of the reaction was determined to be \Updelta_\textr H_\textm^q = 3 6 9. 4 9 ±0. 5 6   \textkJ·\textmol ^{- 1} . \Updelta_{\text{r}} H_{\text{m}}^{\theta } = 3 6 9. 4 9 \pm 0. 5 6 \;{\text{kJ}}\cdot {\text{mol}}^{ - 1} . According to the above results and the relevant data in the literature, through Hess’ law, the standard molar enthalpy of formation of [Dy(m-NBA)₃phen]₂·4H₂O(s) was estimated to be \Updelta_\textf H_\textm^q \Updelta_{\text{f}} H_{\text{m}}^{\theta } [[Dy(m-NBA)₃phen]₂·4H₂O(s), 298.15 K] = −5525 ± 6 kJ·mol⁻¹.     

Solvent extraction of technetium(VII) by primary amine in heptane solution from aqueous alkaline solution

Technetium(VII) extraction has been investigated to obtain useful information concerming the back-extraction of Tc(VII). Radioactive technetium-95m was used to determine the distribution ratio (D _Tc) of^95mTcO ₄ ^– for Tc(VII) extraction using Primene JMT (RNH₂) in heptane solution. An emulsion formation did not occur in the ammonium carbonate system but occurred in the sodium hydroxide solutions. The extraction mechanism has also determined by using the slope analysis method to study the relationships between logD _Tc and log [RNH₂], and between logD _Tc and pH.