Similarity examination of truncated virial equation of state correspondence to linear isothermal regularity (LIR) by applying square-well (SW) potential

Linear isotherm regularity works very well for fluids at high densities, and it has been shown that it is compatible with the EOSs based on statistical–mechanical theory. On the other hand, at low densities, the first few terms of virial EOS have the most contribution to express the deviations from ideal behavior. For finding similarities between dense and dilute states, experimental p–v–T data of 14 fluids (He, Ne, Ar, Kr, H₂, O₂, N₂, CO, NH₃, CH₃OH, CH₄, C₂H₄, C₂H₆ and C₃H₈) are examined. Comparing the thermal dependencies of the attraction and repulsion terms (A and B) of the LIR with the second and third virial coefficients (B ₂ and B ₃) in liquid and supercritical regions (0.7 < T _r < 3.0) shows a remarkable similarity. Square-well potential is applied to examination and comparison of theoretical results with experimental results. It is shown that in liquid and supercritical regions, (1) the short-range potential governs among particles in dense fluids, and the long-range interactions become important in the less dense fluid, (2) similar to Boyle temperature, T _B, in dilute state, there is a temperature as T′_B (in dense fluids) that the attractive forces and the repulsive forces acting on the dense-fluid particles balance out; thus, probably there is a maximum σ (molecular diameter) at nearly 2T _c (T′_B), and (3) in the liquid and supercritical regions (0.7 < T _r < 3.0), in the first-order approximation, there are no significant interactions higher than triple interactions in dense-fluid particles.     

Thermodynamic characteristics of complexation between Ho<Superscript>3+</Superscript> and ethylenediamine-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>'-disuccinic acid in aqueous solutions at 298.15 K

The thermodynamic characteristics of complexation between ethylenediamine-N,N'-disuccinic acid (H₄Y; EDDA) and Ho³⁺ ion were determined calorimetrically and potentiometrically at 298.15 K and ionic strengths of 0.1, 0.5, 1.0, and 1.5 (KNO₃). The logK, Δ_rG, Δ_rH, and Δ_rS values for the formation of HoY^– and HOHY complexes were calculated at the studied and zero ionic strength values. The changes in thermodynamic parameters of the reactions are discussed.     

A comparison of energy changes accompanying growth processes by <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

Calculations are made using the equations Δ_r G = Δ_r H ? TΔ_r S and Δ_r X = Δ_r H ? Δ_r Q where Δ_r X represents the free energy change when the exchange of absorbed thermal energy with the environment is represented by Δ_r Q. The symbol Q has traditionally represented absorbed heat. However, here it is used specifically to represent the enthalpy listed in tabulations of thermodynamic properties as (H _T  ? H ₀) at T = 298.15 K, the reason being that for a given substance TS equals 2.0 Q for solid substances, with the difference being greater for liquids, and especially gases. Since Δ_r H can be measured, and is tangibly the same no matter what thermodynamics are used to describe a reaction equation, a change in the absorbed heat of a biochemical growth process system as represented by either Δ_r Q or TΔ_r S would be expected to result in a different calculated value for the free energy change. Calculations of changes in thermodynamic properties are made which accompany anabolism; the formation of anabolic, organic by-products; catabolism; metabolism; and their respective non-conservative reactions; for the growth of Saccharomyces cerevisiae using four growth process systems. The result is that there is only about a 1% difference in the average quantity of free energy conserved during growth using either Eq. 1 or 2. This is because although values of TΔ_r S and Δ_r Q can be markedly different when compared to one another, these differences are small when compared to the value for Δ_r G or Δ_r X.     

Thermodynamic properties and functions of condensed Bi<Subscript>8</Subscript>O<Subscript>11</Subscript>

The values of ΔH°₂₉₈, S°₂₉₈, H°₂₉₈–H°₀, T, ΔH _fus, and C _p(T), as well as the temperature dependences of the Gibbs energy function, are calculated for Bi₈O₁₁ oxide by proven computational methods.     

The thermal properties of water-n,n-dimethylformamide solutions at 278–323.15 K and 0.1–100 MPa

The isothermal compressibility coefficients κ _T , volumetric thermal expansion coefficients α, and pressure coefficients (?p/?T) _v were calculated for water-N,N-dimethylformamide (DMFA) mixtures of 12 compositions over the temperature and pressure ranges 278–323.15 K and 0.1–100 MPa. The composition dependences of κ _T passed minima, and the corresponding α and (?p/?T) _v dependences passed maxima. The structural features of water and hydrophobic hydration effects were found to play a determining role in changes in the thermodynamic properties of water-DMFA solutions.     

Chemical composition and properties of films produced from hexamethyldisilazane by plasma-enhanced chemical vapor deposition

Relationships between the chemical composition of the gas phase and the properties of SiC_xN_yH_z films produced from hexamethyldisilazane by plasma-enhanced chemical vapor deposition have been studied. The plasma composition has been examined by optical emission spectroscopy. Thermal analysis of the films with simultaneous mass spectrometric detection of released gases has been performed. On the basis of the results and published data, mechanisms for the formation of films by plasma polymerization have been proposed and the film growth at a low plasma power and high reactor temperatures has been found to follow the heterogeneous mechanism.     

Crystal structure of potassium dysprosium octacyanotungstate(IV) heptahydrate

The crystal structure of KDyW(CN)₈ · 7H₂O was determined by X-ray diffraction. The crystals are triclinic, space group PI, a = 7.6284(7) Å, b = 9.2435(9) Å, c = 14.4778(14) Å, α = 80.673(11)°, β = 87.561(11)°, γ = 77.603(11)°, V = 983.86(16) ų, Z = 2, ρ_calcd = 2.429 g/cm³, R = 0.0249, w _R = 0.0502 for 3601 independent reflections. The coordination polyhedron of tungsten is a highly deformed tetragonal antiprism [W(CN)₈], that of dysprosium is a tetragonal antiprism [DyN₄(H₂O)₄]. Some cyano groups are bridging being coordinated to tungsten and dysprosium by C and N atoms, respectively, and form a 3D structure via potassium atoms. The coordination polymer can be described as {[K(H₂O)][Dy(H₂O)₄][W(CN)₈]}n· 2nH₂O.     

Directed Aminomethylation of Pyrrole,Indole, and Carbazole with <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N′</Emphasis>,<Emphasis Type="Italic">N′</Emphasis>-Tetramethylmethanediamine

Catalytic aminomethylation of pyrrole and indole with N,N,N′,N′-tetramethylmethanediamine in the presence of 5 mol % of ZrOCl₂·8H₂O proceeds selectively at the positions 2, 5 of pyrrole and 1, 3 of indole. Carbazole under the same conditions affords 3-formyl-9-aminomethyl derivative. The reaction in the presence of 5 mol % of K₂CO₃ occurs as monoaminomethylation: for pyrrole at the position 2, for indole at the position 3, and for carbazole at the nitrogen atom of the substrate. Water-soluble 1,1′-(1H-pyrrole-2,5-diyl)bis(N,N-dimethylmethanamine) exhibits a fungistatic activity with respect to phytopathogenic fungi Rhizoctonia solani.     

Thermoresponsive behavior of water-salt solutions of a graft copolymer with a main polyimide chain and side poly(<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethylamino-2-ethyl methacrylate) side chains

The water-salt solutions of the graft copolymer bearing a polyimide main chain and poly(N,N-dimethylamino-2-ethyl methacrylate) side chains (M = 4.7 × 10⁵, the density of grafting with side chains z = 0.44) are studied by static and dynamic light scattering and turbidimetry. The solutions are investigated in a tenfold range of NaCl concentrations (from 0.015 to 0.15 mol/L) at the polymer concentration from 0.002 to 0.015 g/cm³ and pH from 8 to 12. The temperature dependences of the intensity of scattered light, optical transmission, hydrodynamic radius of scattering objects, and their concentrations in solutions are derived. The temperatures of phase separation onset T ₁ and end T ₂ are determined. It is shown that an increase in the salt content in solution leads to reduction in the polymer solubility and in temperatures T ₁ and T ₂. The watersalt solutions retain all the regularities of phase-separation temperature variation observed for aqueous solutions with change in the concentration of solution and pH of a medium: the values of T ₁ and T ₂ increase upon dilution and growth of acidity.     

Syntheses,structures, and solid-state phosphorescence characteristics of <Emphasis Type="Italic">trans</Emphasis>-bis(salicylaldiminato)Pt(II) complexes bearing perpendicular <Emphasis Type="Italic">N</Emphasis>-aryl functionalities

The syntheses, structures, and solid-state emission characteristics of trans-bis(salicylaldiminato)Pt(II) complexes bearing N-aromatic functionalities are described herein. A series of Pt complexes bearing various N-phenyl (1) and N-(1-naphthyl) (2) groups on the salicylaldiminato ligands were prepared by reacting PtCl₂(CH₃CN)₂ with the corresponding N-salicylidene aromatic amines, and the trans-coordination and crystal packing of these complexes were unequivocally established based on X-ray diffraction (XRD). Complexes with 2,6-dimethylphenyl (1c), 2,6-diisopropylphenyl (1d), 1-naphthyl (2a), and 1-(2-methylnaphthyl) (2b) groups on the N atoms exhibited intense phosphorescent emission at ambient temperature in the crystalline state, while those with phenyl (1a), 2,6-dibromophenyl (1b), and 2,6-bis(N,N-dimethylamino)phenyl (1e) functionalities were either less emissive or non-emissive under the same conditions. XRD analyses identified significant intramolecular interactions between Pt and H atoms of the N-aryl functionalities in the emissive crystals of 1c, 1d, and 2a. These interactions were evidently an important factor associated with intense emission at ambient temperature.     

A nonparametric scaling equation of state for liquids

A new nonparametric scaling equation of state is suggested. The equation correctly describes the p-ρ-T data and heat capacities of liquids close to the critical vaporization points. It was obtained with the use of the S spinodal and the mixing of scaling fields as a first approximation (asymmetric and nonasymptotic terms were ignored). The new equation was used to approximate the data on ⁴He, C₂H₄, and H₂O in the critical region. The results showed that it correctly described the critical behavior of thermodynamic functions, including isochoric heat capacity, not only in the asymptotic but also over a fairly wide density region at the critical point. The suggested equation of state describes the p-ρ-T data with the same error as the Schofield parametric equation of state. The new equation, however, better reproduces the behavior of heat capacities and is much simpler to use. As distinct from the Schofield equation, the new equation, like classic equations of state, allows the spinodal to be determined from the (?p/?v) _T = 0 condition at T < T _c .     

Characterization of neutron spectrum at Es-Salam Research Reactor using Høgdahl convention and Westcott formalism for the k<Subscript>0</Subscript>-based neutron activation analysis

For the general applicability of the k ₀-NAA method two formalisms were carried out to deal with “1/ν and non-l/ν ((n,γ)” reaction nuclides, respectively. In the Høgdahl-formalism the reactor neutron spectrum parameters, such as α and f were measured using three methods: Cd-ratio, Cdcovered and bare triple monitors. In addition, bare bi-isotopic method using Zr is also utilized for the calculation of f. According to the Westcottformalism the modified spectral index r(α)√T _n /T ₀ and g(T _n ) factor for monitoring neutron temperature T _n , were measured employing Lu as non “1/v” monitor and ¹⁹⁷Au, ⁹⁶Zr and ⁹⁴Zr as “1/v” monitors. The reduced resonance integral of lutetium s _0,Lu was also calculated. To evaluate the applicability of k ₀-NAA in our analytical system, the analysis of two kinds of SRMs was executed. The analytical results showed that the relative error of most of the elements was less than 10%.     

Crystal structures of a family of layered coordination polymers containing divalent metal ions (Mn<Superscript>2+</Superscript>, Co<Superscript>2+</Superscript>, Ni<Superscript>2+</Superscript> and Zn<Superscript>2+</Superscript>) and the 3-amino 4-methyl benzoate ion

The syntheses and crystal structures of the layered coordination polymers M(C₈H₈NO₂)₂ [M = Mn (1), Co (2), Ni (3) and Zn (4)] are described. These isostructural compounds contain centrosymmetric trans-MN₂O₄ octahedra as parts of infinite sheets; the ligand bonds to three adjacent metal ions in μ³-N,O,O′ mode from both its carboxylate O atoms and its amine N atom. In each case, weak intra-sheet N–H?O and C–H?O hydrogen bonds may help to consolidate the structure. Crystal data: 1, C₁₆H₁₆MnN₂O₄, M _r = 355.25, monoclinic, P2₁/c (No. 14), a = 10.6534(2) Å, b = 4.3990(1) Å, c = 15.5733(5) Å, β = 95.1827(10)°, V = 726.85(3) ų, Z = 2, R(F) = 0.026, wR(F ²) = 0.067. 2, C₁₆H₁₆CoN₂O₄, M _r = 359.24, monoclinic, P2₁/c (No. 14), a = 10.6131(10) Å, b = 4.3374(4) Å, c = 15.3556(17) Å, β = 95.473(4)°, V = 703.65(12) ų, Z = 2, R(F) = 0.041, wR(F ²) = 0.091. 3, C₁₆H₁₆N₂NiO₄, M _r = 359.02, monoclinic, P2₁/c (No. 14), a = 10.6374(4) Å, b = 4.2964(2) Å, c = 15.2827(8) Å, β = 95.9744(14)°, V = 694.66(6) ų, Z = 2, R(F) = 0.028, wR(F ²) = 0.070. 4, C₁₆H₁₆N₂O₄Zn, M _r = 365.68, monoclinic, P2₁/c (No. 14), a = 10.6385(5) Å, b = 4.2967(3) Å, c = 15.2844(8) Å, β = 95.941(3)°, V = 694.89(7) ų, Z = 2, R(F) = 0.038, wR(F ²) = 0.107.     

Crystal structures of two one-dimensional coordination polymers constructed from Mn<Superscript>2+</Superscript> ions,chelating hexafluoro-acetylacetonate anions,and flexible bipyridyl bridging ligands

The syntheses and crystal structures of two one-dimensional coordination polymers, [Mn(C₅HO₂F₆)₂(C₁₆H₂₀N₂)] _n (1) and [Mn(C₅HO₂F₆)₂(C₂₀H₂₀N₂)] _n (2), are described, where C₅HO₂F₆ ^? is the hexafluoro acetylacetonate anion, C₁₆H₂₀N₂ is 1,6-bis(4-pyridyl)-hexane, and C₂₀H₂₀N₂ is 1,4-bis[2-(3-pyridyl)ethyl]-benzene. In both phases, the metal ion lies on a crystallographic twofold axis and is coordinated by two chelating C₅HO₂F₆ ^? anions and two bridging bipyridyl ligands to generate a cis-MnN₂O₄ octahedron. The bridging ligands, which are completed by crystallographic inversion symmetry in both compounds, connect the metal nodes into zigzag [20 1 ] chains in 1 and contorted [001] chains in 2. Intrachain C–H???O interactions occur in 1 but not in 2, which may be correlated with the relative orientations of the ligands. Crystal data: 1, C₂₆H₂₂F₁₂MnN₂O₄, M _r = 709.40, monoclinic, C2/c (No. 15), a = 9.3475(2) Å, b = 16.6547(3) Å, c = 18.3649(4) Å, β = 91.1135(8)°, V = 2858.50(10) ų, Z = 4, R(F) = 0.030, w R(F ²) = 0.075. 2, C₃₀H₂₂F₁₂MnN₂O₄, M _r = 757.44, monoclinic, C2/c (No. 15), a = 19.9198(2) Å, b = 10.6459(2) Å, c = 16.8185(3) Å, β = 119.8344(8)°, V = 3093.91(9) Å3, Z = 4, R(F) = 0.032, w R(F ²) = 0.078.     

Evaporation of Plasticizer from NEPE Type Propellant

Using the method of dynamic thermogravimetry and differential scanning calorimetry in the heating rate range 0.46–10.0 deg^–1 min^–1, evaporation of the plasticizer from propellant samples of the NEPE type was investigated. The experiments were carried out in an open system in a flow of pure argon at atmospheric pressure. Nitroglycerin is the main mass fraction of the plasticizer. The activation energy E of the gross evaporation–diffusion process is determined by various methods. Heat of evaporation of the plasticizer ΔH_v is estimated. It is shown that in the early stage of evaporation the values of E and ΔH_v practically coincide. At a temperature of 298.15 K ΔH_v = 89 ± 4 kJ mol^–1, which is in satisfactory agreement with the literature data for heat of evaporation of pure nitroglycerin. With any way of preventing free removal of the plasticizer from the surface of the samples on the DSC thermograms successive exothermic peaks of the thermal decomposition of the plasticizer and the octogen are observed, which are not realized in the open system for the indicated heating rates at T < 190°C.     

Transport and physicochemical parameters of polypentenamer

Physicochemical properties of a cis-polypentenamer—a hydrocarbon polymer with a low glass transition temperature (T _g = 168.8 K)—have been studied. Measurements of permeability coefficients P in rubbery material for a wide range of gases (He, H₂, O₂, N₂, CO₂, CH₄, C₂H₆, C₃H₈, and n-C₄H₁₀) indicate a high permeability of this polymer for which the values of P are only slightly lower than those of the most permeable rubber—poly(dimethylsiloxane). The method of inverse gas chromatography has been employed to estimate solubility coefficients S for n alkanes C₃–C₁₀ and cycloalkanes in cis-polypentenamer in the range from 25 to 150°C. It has been shown that the solubility coefficients linearly increase in lnS-T _cr ² coordinates, where T _cr is the critical temperature of a solute. In terms of the above correlation, the solubility coefficients of light gases have been estimated and the diffusion coefficients D of gases in the same polymer have been calculated via the formula P=DS. The free volume in cis-polypentenamer has been studied by positron annihilation lifetime spectroscopy. The temperature dependence of the positronium lifetime τ ₃ that characterizes the size of the free volume element in a polymer demonstrates saturation at temperatures above 250 K. This effect is probably related to a rapid migration of fluctuation holes in the rubbery polymer at temperatures remote enough from its glass transition temperature.     

Geometric and electronic structure of an N,N′-ethylene-bis(salicylaldiminato) zinc(II) molecule,ZnO<Subscript>2</Subscript>N<Subscript>2</Subscript>C<Subscript>16</Subscript>H<Subscript>14</Subscript>

Gas electron diffraction at a temperature T of 641(5) K is used to study the structure of an N,N′-ethylenebis(salicylaldiminato) zinc(II) molecule, ZnO₂N₂C₁₆H₁₄, further Zn(salen). The structure of a gaseous Zn(salen) complex has C ₂ symmetry and is characterized by a substantial turn of two chelating fragments of the ligand with respect to each other, and also by a big difference in the length of coordination bonds: r _h1(Zn-O)=1.902(7) Å r _h1(Zn-N)= 2.027(7) Å. Results of the DFT/B3LYP calculation with 6-31G* and CEP,TZV basis sets of the molecule structure well agree with the experimental data. The electronic structure of Ni(salen), Cu(salen), Zn(salen), and Zn(acacen) molecules is considered.     

A novel 3D energetic coordination polymer containing Co(II) atoms in a pentanuclear cluster

A novel coordination polymer [Co₅(OH)₂(dnbpdc)₄(H₂O)₆]·16H₂O (1) (dnbpdc = 6,6′-dinitro-4,4′-biphenyldicarboxylic acid) is obtained from a hydrothermal reaction. The structure of complex 1 is characterized by elemental analysis, IR spectroscopy, and single crystal X-ray diffraction analysis. The title compound (C₅₆H₇₀Co₅N₈O₅₆, M _r = 2045.85) crystallizes in the triclinic space group P-1 with a = 11.9349(2) Å, b = 12.1895(2) Å, c = 15.420(2) Å, α = 109.390(7)°, β = 94.786(1)°, γ = 108.027(9)°, V = 1968.4(4) ų, Z = 1, D _c = 1.726 g/cm³, F(000) = 1045, μ(MoK _α) = 1.154 mm^–1, T = 133(2) K, the final R = 0.0316 and wR = 0.0692 for 7032 observed reflections with I > 2σ(I). The coordination polymer is built of a pentanuclear Co(II) cluster, four dnbpdc ligands, two hydroxyl groups, six coordination water and sixteen crystal water molecules. Ligand oxygen atoms exhibit three types of coordination modes (monodentate, syn-syn bridging bidentate and bridging tridentate). Moreover, the infinite three-dimensional supramolecular network is generated by coordination and hydrogen bonds. The thermal stability of complex 1 is evaluated by differential scanning calorimetry and thermogravimetric analysis.     

Catalytic effects of cationic nanoparticle (CTABr/NaX/H<Subscript>2</Subscript>O,X = Cl,Br) for the piperidinolysis of phenyl salicylate ions

The expression of pseudo-second-order rate constants (k _X) for cationic nanoparticle (CN) [CTABr/NaX/H₂O, X = Br, Cl, CTABr = cetyltrimethylammonium bromide] catalyzed piperidinolysis-ionized phenyl salicylate (PSa^–), at constant [CTABr]_T, 0.1 M piperidine (Pip), and 35°C, were calculated from the relationship: k _obs = (k ₀ + k _X[NaX])/(1 + K ^X/S[NaX]), in which k ₀, k _X, and K ^X/S are constant kinetic parameters and k _obs represents the pseudo-first-order rate constant for Pip reaction with phenyl salicylate ion in the presence of CN. The source of the large catalytic effect of CN catalyst was shown to be due to the transfer of PSa^– from pseudo-phase of the CNs to the bulk aqueous phase through X^–/PSa^– ion exchange at the surface of the CNs.     

The thermodynamic properties of 5-vinyltetrazole and poly-5-vinyltetrazole over the temperature range from <Emphasis Type="Italic">T</Emphasis> → 0 to 350 K

The temperature dependences of the heat capacities of 5-vinyltetrazole and poly-5-vinyltetrazole were measured by adiabatic vacuum calorimetry over the temperature range 6-(350–370) K with errors of ～0.2%. The results were used to calculate the thermodynamic functions of the compounds, C _p ^° , H ^°(T) - H ^°(0), S ^°(T), and G ^°(T) - H ^°(0), over the temperature range from T → 0 to 350–370 K. The energy of combustion of 5-vinyltetrazole and poly-5-vinyltetrazole was measured in an isothermic-shell static bomb calorimeter. The standard enthalpies of combustion Δ _c H ^° and thermodynamic characteristics of formation Δ_f H ^°, Δ_f S ^°, and Δ_f G ^° at 298.15 K and p = 0.1 MPa were calculated. The results were used to determine the thermodynamic characteristics of polymerization of 5-vinyltetrazole over the temperature range from T → 0 to 350 K.