Exact transient solutions of kinetics of first‐order reactions with end effects

The finite set of rate equations C _m,n ^' =α _n,n-1 C _m,n-1 (t)+α _n,n C _m,n (t)+α _n,n+1 C _m,n+1 (t), $$0 \leqslant m \leqslant N,0 \leqslant n \leqslant N,$$ where $$\alpha _{i,j}$$ are $\alpha _{j,j - 1} = A,\alpha _{j,j} = - \left( {A + B} \right),\alpha _{j,j + 1} = B$ , with $\alpha _{0,0} = - \alpha _{1,0} = - \alpha$ and $\alpha _{N,N} = - \alpha _{N - 1,N} = - b,\alpha _{0, - 1} = \alpha _{N,N + 1} = 0$ , subject to the initial condition $C_{m,n} \left( 0 \right) = \delta _{n,m}$ (Kronecker delta) for some $m$ , arises in a number of applications of mathematics and mathematical physics. We show that there are five sets of values of $a$ and $b$ for which the above system admits exact transient solutions.     

Theoretical study of proton transfer in ammonia–hydrogen halides in the presence of methanol

In this work, the effect of solvent (methanol, CH₃OH) molecules on proton transfer (PT) between ammonia and hydrogen halides was studied. We performed MP2 and B3LYP calculations on HX–NH₃–(CH₃OH) _n clusters for three hydrogen halides, HF, HCl, and HBr, with the number of methanol molecules varying from none to three (n = 0–3). The results showed that stepwise association of methanol molecules with the gas-phase complex can eventually facilitate ionization within the complex, producing the $ {\text{NH}}_{4}^{ + } {\text{X}}^{ - } - \left( {{\text{CH}}_{ 3} {\text{OH}}} \right)_{\text{n}} $ cluster. We found that PT occurs on addition of from one (for HBr) to three (for HF) methanol molecules. The interaction energy $ E_{\text{int}} $ and $ \Updelta E_{\text{add}} $ for the complexes were calculated and basis set superposition error (BSSE) correction was also performed. Atoms-in-molecule and natural-bond-orbital analysis were used to study the properties of the hydrogen bonds in the complexes.     

Isosaccharinate Complexes of Fe(III)

Prior to this study there were no thermodynamic data for isosaccharinate (ISA) complexes of Fe(III) in the environmental range of pH (>~4.5). This study was undertaken to obtain such data in order to predict Fe(III) behavior in the presence of ISA. The solubility of Fe(OH)₃(2-line ferrihydrite), referred to as Fe(OH)₃(s), was studied at 22?±?2?°C in: (1) very acidic (0.01?mol·dm^?3 H⁺) to highly alkaline conditions (3?mol·dm^?3 NaOH) as a function of time (11?C421?days), and fixed concentrations of 0.01 or 0.001?mol·dm^?3 NaISA; and (2) as a function of NaISA concentrations ranging from approximately 0.0001 to 0.256?mol·dm^?3 and at fixed pH values of approximately 4.5 and 11.6 to determine the ISA complexes of Fe(III). The data were interpreted using the SIT model that included previously reported stability constants for $ {{\text{Fe(ISA}})_{n}}^{3 - n} $ (with n varying from 1 to 4) and Fe(III)?COH complexes, and the solubility product for Fe(OH)₃(s) along with the values for two additional complexes (Fe(OH)₂(ISA)(aq) and $ {\text{Fe(OH)}}_{ 3} ( {{\text{ISA}})_{2}}^{2 - } $ ) determined in this study. These extensive data provided a log₁₀ K ⁰ value of 1.55?±?0.38 for the reaction $ ({\text{Fe}}^{ 3+ } + {\text{ISA}}^{-} + 2 {\text{H}}_{ 2} {\text{O}} \rightleftarrows {\text{Fe(OH}})_{ 2} {\text{ISA(aq}}) + 2 {\text{H}}^{ + } ) $ and a value of ?3.27?±?0.32 for the reaction $ ({\text{Fe}}^{ 3+ } + 2 {\text{ISA}}^{-} + 3 {\text{H}}_{ 2} {\text{O}} \rightleftarrows {\text{Fe(OH)}}_{ 3} ( {\text{ISA}})_{2}^{2 - } + 3 {\text{H}}^{ + } ) $ and show that ISA forms strong complexes with Fe(III) which significantly increase the Fe(OH)₃(s) solubility at pH?<~12. Thermodynamic calculations show that competition of Fe(III) with tetravalent ions for ISA does not significantly affect the solubilities of tetravalent hydrous oxides (e.g., Th and Np(IV)) in ISA solutions.     

Effects of Ions on the OH Stretching Band of Water as Revealed by ATR-IR Spectroscopy

The effects of various cations (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mn²⁺, Co²⁺, and Ni²⁺) and anions (Cl^?, Br^?, I^?, \( {\text{NO}}_{3}^{ - } \) , \( {\text{ClO}}_{4}^{ - } \) , \( {\text{HCO}}_{3}^{ - } \) , and \( {\text{CO}}_{3}^{2 - } \) ) on the molar absorptivity of water in the OH stretching band region (2,600–3,800 cm^?1) were ascertained from attenuated total reflection infrared spectra of aqueous electrolyte solutions (22 in all). The OH stretching band mainly changes linearly with ion concentrations up to 2 mol·L^?1, but several specific combinations of cations and anions (Cs₂SO₄, Li₂SO₄, and MgSO₄) present different trends. That deviation is attributed to ion pair formation and cooperativity in ion hydration, which indicates that the extent of the ion–water interaction reflected by the OH stretching band of water is beyond the first solvation shell of water molecules directly surrounding the ion. The obtained dataset was then correlated with several quantitative parameters representing structural and dynamic properties of water molecules around ions: ΔG _HB, the structural entropy (S _str), the viscosity B-coefficient (B _η ), and the ionic B-coefficient of NMR relaxation (B _NMR). Results show that modification of the OH stretching band of water caused by ions has quasi-linear relations with all of these parameters. Vibrational spectroscopy can be a useful means for evaluating ion–water interaction in aqueous solutions.     

Significance of water quality and radiation wavelength for UV photolysis of PhCs in simulated mixed solutions

Ultraviolet (UV) photolysis of sixteen pharmaceutical compounds (PhCs) in mixed solutions with four types of water and two sets of UV radiation was investigated. UVC (254 nm) photolysis was ineffective at eliminating a large number of PhCs while a big number of them were refractory. However, vacuum UV (VUV: 185 nm + 254 nm) photolysis in the same experimental conditions eliminated the PhCs almost completely. The eliminations in ultrapure water (UPW), tap water (TW) and Neya River water (NRW) and their organic/inorganic contents were inversely correlated, which was more evident in VUV photolysis. Natural organic matter (NOM) in NRW did not have an impact in indirect photolysis, but effluent organic matter (EfOM) in secondary-treated effluent (NWTPE) enhanced indirect photolysis, which was more evident in VUV photolysis underlining the point that radiation wavelength/intensity can be a limiting factor in organic-rich waters. Moreover, VUV photolysis was far superior (90% mineralization) to UVC photolysis (10% mineralization) for PhCs mineralization. The greatly enhanced elimination and mineralization efficiencies observed for VUV photolysis were attributed to accelerated direct photolysis with 185 nm wavelength and indirect photolysis involving ^·OH. The results demonstrated efficacy of VUV photolysis in wastewater treatment and its potential use as a tertiary treatment.      

Effect of size of tetraalkylammonium counterions on the temperature dependent micellization of AOT in aqueous medium

Different tetraalkylammonium, viz. N⁺(CH₃)₄, N⁺(C₂H₅)₄, N⁺(C₃H₇)₄, N⁺(C₄H₉)₄ along with simple ammonium salts of bis (2-ethylhexyl) sulfosuccinic acid have been prepared by ion-exchange technique. The critical micelle concentration of surfactants with varied counterions have been determined by measuring surface tension and conductivity within the temperature range 283–313 K. Counterion ionization constant, α, and thermodynamic parameters for micellization process viz., $\Delta G_m^{\text{0}} $ , $\Delta H_m^{\text{0}} $ , and $\Delta S_m^{\text{0}} $ and also the surface parameters, Γ_max and A_min, in aqueous solution have been determined. Large negative $\Delta G_m^{\text{0}} $ of micellization for all the above counterions supports the spontaneity of micellization. The value of standard free energy, $\Delta G_m^{\text{0}} $ , for different counterions followed the order $${\text{N}}^{\text{ + }} \left( {{\text{CH}}_{\text{3}} } \right)_4 >{\text{NH}}_{\text{4}}^{\text{ + }} >{\text{Na}}^{\text{ + }} >{\text{N}}^{\text{ + }} \left( {{\text{C}}_{\text{2}} {\text{H}}_5 } \right)_{\text{4}} {\text{ $>$ N}}^{\text{ + }} \left( {{\text{C}}_{\text{3}} {\text{H}}_{\text{7}} } \right)_4 >{\text{N}}^{\text{ + }} \left( {{\text{C}}_{\text{4}} {\text{H}}_{\text{9}} } \right)_4 $$ , at a given temperature. This result can be well explained in terms of bulkiness and nature of hydration of the counterion together with hydrophobic and electrostatic interactions.     

A thermodynamic study of complexation of 18-crown-6 with Zn2+, Tl+, Hg2+ and {\text{UO}}^{{{\text{2 + }}}}_{{\text{2}}} cations in acetonitrile-dimethylformamide binary media and study the effect of anion on the stability constant of (18C6-Na+) complex in methanol solutions

The equilibrium constants and thermodynamic parameters for complex formation of 18-crown-6(18C6) with Zn²⁺, Tl⁺, Hg²⁺ and $ {\text{UO}}^{{{\text{2 + }}}}_{{\text{2}}} $ cations have been determined by conductivity measurements in acetonitrile(AN)-dimethylformamide(DMF) binary solutions. 18-crown-6 forms 1:1 complexes [M:L] with Zn²⁺, Hg²⁺ and $ {\text{UO}}^{{{\text{2 + }}}}_{{\text{2}}} $ cations, but in the case of Tl⁺ cation, a 1:2 [M:L₂] complex is formed in most binary solutions. The thermodynamic parameters ( $ \Delta {\text{H}}^{ \circ }_{{\text{c}}} $ and $ \Delta {\text{S}}^{ \circ }_{{\text{c}}} $ ) which were obtained from temperature dependence of the equilibrium constants show that in most cases, the complexes are enthalpy destabilized but entropy stabilized and a non-monotonic behaviour is observed for variations of standard enthalpy and entropy changes versus the composition of AN/DMF binary mixed solvents. The obtained results show that the order of selectivity of 18C6 ligand for these cations changes with the composition of the mixed solvent. A non-linear relationship was observed between the stability constants (logK_f) of these complexes with the composition of AN/DMF binary solutions. The influence of the $ {\text{ClO}}^{ - }_{{\text{4}}} $ , $ {\text{NO}}^{ - }_{{\text{3}}} $ and $ {\text{Cl}}^{ - } $ anions on the stability constant of (18C6-Na⁺) complex in methanol (MeOH) solutions was also studied by potentiometry method. The results show that the stability of (18C6-Na⁺) complex in the presence of the anions increases in order: $ {\text{ClO}}^{ - }_{{\text{4}}} $  >  $ {\text{NO}}^{ - }_{{\text{3}}} $  >  $ {\text{Cl}}^{ - } $ .     

Three–step method to determine the eutectic composition of binary and ternary mixtures

A three-step method to determine the eutectic composition of a binary or ternary mixture is introduced. The method consists in creating a temperature–composition diagram, validating the predicted eutectic composition via differential scanning calorimetry and subsequent T-History measurements. To test the three-step method, we use two novel eutectic phase change materials based on \(\mathrm{Zn}(\hbox {NO}_3)_2\cdot 6\mathrm{H}_{2}{\mathrm O}\) and \(\mathrm{NH}_4\mathrm{NO}_3\)   respectively \(\mathrm{Mn}(\hbox {NO}_3)_2\cdot 6\mathrm{H}_{2}{\hbox {O}}\) and \(\mathrm{NH}_4\mathrm{NO}_3\) with equilibrium liquidus temperatures of 12.4 and 3.9  \(\,^{\circ }\mathrm {C}\) respectively with corresponding melting enthalpies of 135 J \(\mathrm{g}^{-1}\) (237 J \(\mathrm{cm}^{-3}\) ) respectively 133 J \(\mathrm{g}^{-1}\) (225 J \(\mathrm{cm}^{-3}\) ). We find eutectic compositions of 75/25 mass% for \(\mathrm{Zn}(\hbox {NO}_3)_2\cdot \mathrm{6H}_{2}{\mathrm{O}}\) and \(\mathrm{NH}_4\mathrm{NO}_3\) and 73/27 mass% for \(\mathrm{Mn}(\hbox {NO}_3)_2\cdot 6\mathrm{H}_{2}{\mathrm{O}}\) and \(\mathrm{NH}_4\mathrm{NO}_3\) . Considering a temperature range of 15 K around the phase change, a maximum storage capacity of about 172 J \(\mathrm{g}^{-1}\) (302 J \(\mathrm{cm}^{-3}\) ) respectively 162 J \(\mathrm{g}^{-1}\) (274 J \(\mathrm{cm}^{-3}\) ) was determined for \(\mathrm{Zn}(\hbox {NO}_3)_2\cdot \mathrm{6H}_{2}{\mathrm{O}}\) and \(\mathrm{NH}_4\mathrm{NO}_3\) respectively \(\mathrm{Mn}(\hbox {NO}_3)_2\cdot \mathrm{6H}_{2}{\mathrm{O}}\) and \(\mathrm{NH}_4\mathrm{NO}_3\) .     

Acid–Base Properties of the \mathrm{Fe}(\mathrm{CN})_{6}^{3-}/\mathrm{Fe}(\mathrm{CN})_{6}^{4-} Redox Couple in the Presence of Various Background Mineral Acids and Salts

The acid?Cbase behavior of $\mathrm{Fe}(\mathrm{CN})_{6}^{4-}$ was investigated by measuring the formal potentials of the $\mathrm{Fe}(\mathrm{CN})_{6}^{3-}$ / $\mathrm{Fe}(\mathrm{CN})_{6}^{4-}$ couple over a wide range of acidic and neutral solution compositions. The experimental data were fitted to a model taking into account the protonated forms of $\mathrm{Fe}(\mathrm{CN})_{6}^{4-}$ and using values of the activities of species in solution, calculated with a simple solution model and a series of binary data available in the literature. The fitting needed to take account of the protonated species $\mathrm{HFe}(\mathrm{CN})_{6}^{3-}$ and $\mathrm{H}_{2}\mathrm{Fe}(\mathrm{CN})_{6}^{2-}$ , already described in the literature, but also the species $\mathrm{H}_{3}\mathrm{Fe}(\mathrm{CN})_{6}^{-}$ (associated with the acid?Cbase equilibrium $\mathrm{H}_{3}\mathrm{Fe}(\mathrm{CN})_{6}^{-}\rightleftharpoons \mathrm{H}_{2}\mathrm{Fe}(\mathrm{CN})_{6}^{2-} + \mathrm{H}^{+}$ ). The acidic dissociation constants of $\mathrm{HFe}(\mathrm{CN})_{6}^{3-}$ , $\mathrm{H}_{2}\mathrm{Fe}(\mathrm{CN})_{6}^{2-}$ and $\mathrm{H}_{3}\mathrm{Fe}(\mathrm{CN})_{6}^{-}$ were found to be $\mathrm{p}K^{\mathrm{II}}_{1}= 3.9\pm0.1$ , $\mathrm{p}K^{\mathrm{II}}_{2} = 2.0\pm0.1$ , and $\mathrm{p}K^{\mathrm{II}}_{3} = 0.0\pm0.1$ , respectively. These constants were determined by taking into account that the activities of the species are independent of the ionic strength.     

Influence of heavy metals on the early hydration of calcium sulfoaluminate

The hydration of calcium sulfoaluminate $ ( {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} ) $ in the presence of heavy metal is essential not only for applying the cement in solidification/stabilization (s/s) process, but also for preparing modern green cements from wastes containing heavy metals. In this study, the influence of gypsum, types, and concentrations of heavy metal nitrates (Pb(NO₃)₂, Cr(NO₃)₃·9H₂O, Cu(NO₃)₂·3H₂O, Zn(NO₃)₂·6H₂O) on the hydration of $ {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} $ during the first 24 h were investigated by isothermal conduction calorimetry, X-ray diffraction, and thermogravimetric analysis. The addition of 20 % of gypsum to $ {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} $ leads to a rapid formation of ettringite against monosulfate and acceleration of hydration. The effects of heavy metals on the hydration of $ {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} $ depend on the types of heavy metals and the addition of gypsum. Without any gypsum addition, heavy metal nitrates such as Cr, Cu, and Zn promote the hydration of $ {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} $ , whereas Pb presents a strong retardation effect at the early age of $ {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} $ hydration. When 20 % of gypsum is added to $ {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} $ , heavy metals tend to accelerate the hydration of the blended pastes except Zn. However, heavy metal containing phases were not detected in this work, which needs to be supplemented by further investigations.     

Density functional theoretical study of A series of pentazolide compounds \hbox{A}_{\it n}(\hbox{N}_5)_{\rm 6-{\it n}}^{\it q} (A = B, Al, Si, P, and S; n = 1–3; q = +1, 0, −1, −2, and −3)

The structure and the stability of pentazolide compounds $\hbox{A}_{\it n}(\hbox{N}_5)_{\rm 6-{\it n}}^{\it q}$ (A = B, Al, Si, P, and S; n= 1–3; q = +1, 0, ?1, ?2, and ?3), as high energy-density materials (HEDMs), have been investigated at the B3LYP/6-311+G* level of theory. The natural bond orbital analysis shows that the charge transfer plays an important role when the $\hbox{A}_{\it n}(\hbox{N}_5)_{\rm 6-{\it n}}^{\it q}$ species are decomposed to $\hbox{A}_{\it n}(\hbox{N}_5)_{\rm 5-{\it n}}\hbox{N}_3^{\it q}$ and N₂. The more negative charges are transferred from the N₂ molecule after breaking the N₅ ring, the more stable the systems are with respect to the decomposition. Moreover, the conclusion can be drawn that ${\hbox{Al}(\hbox{N}_5)_5^{2-}}$ and ${\hbox{Al}_2(\hbox{N}_5)_4^{2-}}$ are predicted to be suitable as potential HEDMs.     

Volumetric properties of a stoichiometric mixture of K+ and Br− ions in H/D isotope-substituted aqueous methanol at 278.15–318.15 K: I. The H2O-CH3OH-KBr system

The densities of potassium bromide solutions in aqueous methanol mixtures have been measured with an error of at most ±(1 × 10^?5) g/cm³ for methanol mole fractions x ₂ of 0.06, 0.1, 0.3, or 0.6 and for the potassium bromide mole fractions up to about 2.65 × 10^?2 at 278.15, 288.15, 298.15, 308.15, and 318.15 K. Limiting partial molar volumes $\overline V _3^\infty $ , excess molar volumes $\overline V _3^{E, \infty } $ , and expansibilities $\overline E _{p, 3}^\infty $ have been calculated for a stoichiometric mixture of solvated K⁺ and Br^? ions in the mixed solvents. In the region of x ₂ ≈ 0.25, $\overline E _{p, 3}^\infty $ changes its sign from positive to negative. The $\overline V _3^{E, \infty } $ (x ₂) trend, on the whole, reflects the topologic features of the molecular structure of aqueous methanol associated through H-bonding.     

Nickel and Cobalt Complexes of Non-protein L-Norvaline and Antioxidant Ferulic Acid: Potentiometric and Spectrophotometric Studies

Binary and mixed-ligand complexes of Ni²⁺ and Co²⁺ involving L-norvaline (Nva) and ferulic acid (FA) have been investigated in aqueous solutions by pH potentiometry and UV?Cvisible spectrophotometric techniques, at 298.15 K and fixed ionic strength (0.15?mol?dm^?3, NaNO₃). The overall stability constants of the Ni²⁺ and Co²⁺ complexes with the ligands studied were obtained by the HYPERQUAD2008 program from the pH-potentiometric data. As a result of the numerical treatment, a model composed of seven species NiNva⁺, NiNva₂, NiNvaH_?1, $\mathrm{NiNva}_{ - 2}^{ -}$ , NiFA, $\mathrm{NiFAH}_{ - 1}^{ -}$ and NiNvaFA^? was obtained for the Ni²⁺+Nva+FA system, whereas for the Co²⁺+Nva+FA system the complexes CoNva⁺, CoNva₂, CoNvaH_?1, $\mathrm{CoNvaH}_{ - 2}^{ -}$ , CoFA, $\mathrm{CoFAH}_{ - 1}^{ -}$ , and CoNvaFA^? were obtained. The complex species distributions in certain pH ranges were calculated by the HySS2009 simulation program. Spectroscopic UV?Cvisible measurements were carried out to give qualitative information about the complexes formed in these solutions.     

The Formation and Stability of the [FePy3Cl3]· Py Clathrate in the Pyridine–Iron(III) Chloride System: Phase Diagram and Solid–Gas Equilibria Study

The phase diagram of the pyridine–iron(III) chloride system has been studied for the 223–423 K temperature and 0–56 mass-% concentration ranges using differential thermal analysis (DTA) and solubility techniques. A solid with the highest pyridine content formed in the system was found to be an already known clathrate compound, [FePy₃Cl₃]·Py. The clathrate melts incongruently at 346.9 ± 0.3 K with the destruction of the host complex: [FePy₃Cl₃]·Py_(solid)=[FePy₂Cl₃]_(solid) + liquor. The thermal dissociation of the clathrate with the release of pyridine into the gaseous phase (TGA) occurs in a similar way: [FePy₃Cl₃]·Py_(solid)=[FePy2Cl₃]_(solid) + 2 Py_(gas). Thermodynamic parameters of the clathrate dissociation have been determined from the dependence of the pyridine vapour pressure over the clathrate samples versus temperature (tensimetric method). The dependence experiences a change at 327 K indicating a polymorphous transformation occurring at this temperature. For the process ${1 \over 2}[\hbox{FePy}_{3}\hbox{Cl}_{3}]\cdot \hbox{Py}_{\rm (solid)} = {1 \over 2}[\hbox{FePy}_{2}\hbox{Cl}_{3}]_{\rm (solid)} + \hbox{Py}_{\rm (gas)}$ in the range 292–327 K, ΔH $^{0}_{298}$ =70.8 ± 0.8 kJ/mol, ΔS $^{0}_{298}$ =197 ± 3 J/(mol K), ΔG $^{0}_{298}$ =12.2 ± 0.1 kJ/mol; in the range 327–368 K, ΔH $^{0}_{298}$ =44.4 ± 1.3 kJ/mol, ΔS $^{0}_{298}$ =116 ± 4 J/(mol K), ΔG $^{0}_{298}$ =9.9 ± 0.3 kJ/mol.     

Thermodynamics of extraction of tetravalent plutonium,uranium, thorium and zirconium

Thermodynamic treatment of the experimental data on the extraction of quadrivalent Pu, U, Th and Zr with tri-n-butyl phosphate (TBP) from nitric acid solutions is presented. It is shown that the extraction of all the quadrivalent metals studied is going according to the same mechanism: M(OH)^4?i+(4?i)NO ₃ ^? +2TBP?M(OH)_i(NO₃)_4?i·2 TBP. For Zr, i=0, 1, and 2; for the remaining M(IV), i=0 and 1. The thermodynamic constants of extraction of M(IV) with the kerosene solutions of TBP according to the above mentioned equation are as follows: Zr: K ₀ ⁰ =0.6; K ₁ ⁰ =14; K ₂ ⁰ =5. Pu: K ₀ ⁰ =380; K ₁ ⁰ =4.8·10⁴. U: K ₀ ⁰ =300; K ₁ ⁰ =1.8·10⁴. Th: K ₀ ⁰ ～150. It has been established that Zr and Pu(IV) are extracted into 2-thenoyltrifluoracetone (HA) from perchloric acid solutions under the formation of MA₄ and M(ClO₄)A₃ species. For the extraction from nitric acid solutions, the species formed are ZrA₄ and Zr(NO₃)A₃ in the case of Zr, PuA₄ and Pu(OH)A₃ in the case of Pu. The differences in the qualitative and quantitative characteristics of the extraction of M(IV) with TBP and HA from nitric and perchloric acids are explained by the effect of the character of the acid and of ionic potential upon the structure of the hydration shell of M _aq ⁴⁺ .     

Symmetry-itemized enumeration of RS-stereoisomers of allenes. I. The fixed-point matrix method of the USCI approach combined with the stereoisogram approach

After the RS-stereoisomeric group \(\mathbf{D}_{2d\widetilde{\sigma }\widehat{I}}\) of order 16 has been defined by starting point group \(\mathbf{D}_{2d}\) of order 8, the isomorphism between \(\mathbf{D}_{2d\widetilde{\sigma }\widehat{I}}\) and the point group \(\mathbf{D}_{4h}\) of order 16 is thoroughly discussed. The non-redundant set of subgroups (SSG) of \(\mathbf{D}_{2d\widetilde{\sigma }\widehat{I}}\) is obtained by referring to the non-redundant set of subgroups of \(\mathbf{D}_{4h}\) . The coset representation for characterizing the orbit of the four positions of an allene skeleton is clarified to be \(\mathbf{D}_{2d\widetilde{\sigma }\widehat{I}}(/\mathbf{C}_{s\widetilde{\sigma }\widehat{I}})\) , which is closely related to the \(\mathbf{D}_{4h}(/\mathbf{C}_{2v}^{\prime \prime \prime })\) . According to the unit-subduced-cycle-index (USCI) approach (Fujita, Symmetry and combinatorial enumeration of chemistry. Springer, Berlin 1991), the subduction of \(\mathbf{D}_{2d\widetilde{\sigma }\widehat{I}}(/\mathbf{C}_{s\widetilde{\sigma }\widehat{I}})\) is examined so as to generate unit subduced cycle indices with chirality fittingness (USCI-CFs). Then, the fixed-point matrix method of the USCI approach is applied to the USCI-CFs. Thereby, the numbers of quadruplets are calculated in an itemized fashion with respect to the subgroups of \(\mathbf{D}_{2d\widetilde{\sigma }\widehat{I}}\) . After the subgroups of \(\mathbf{D}_{2d\widetilde{\sigma }\widehat{I}}\) are categorized into types I–V, type-itemized enumeration of quadruplets is conducted to illustrate the versatility of the stereoisogram approach.     

OH Dynamics in a Nanosecond Pulsed Plasma Filament in Atmospheric Pressure He–H2O upon the Addition of O2

The influence of the addition of O₂ on the OH production in a He + 0.1 % H₂O discharge is investigated using laser induced fluorescence. The plasma properties $(T_{\rm g},\;n_{\rm e})$ are reported and used to explain the observed time and spatially resolved OH density, which is absolutely calibrated using Rayleigh scattering. Compared to the case when only H₂O is added, an increase in the measured OH density is observed in the far afterglow. A zero-dimensional chemical kinetic model is constructed, which allows to determine the reactions responsible for the OH production in the far afterglow. When O₂ is admixed, the key reaction $\hbox{O} + \hbox{OH} \longrightarrow \hbox{O}_{2} + \hbox{H}$ causes quenching of OH and production of increased densities of H, HO₂ and H₂O₂, which subsequently leads to additional OH production in the late afterglow.     

Hydrogen Peroxide Production in an Atmospheric Pressure RF Glow Discharge: Comparison of Models and Experiments

The production of \(\hbox {H}_2\hbox {O}_2\) in an atmospheric pressure RF glow discharge in helium-water vapor mixtures has been investigated as a function of plasma dissipated power, water concentration, gas flow (residence time) and power modulation of the plasma. \(\hbox {H}_2\hbox {O}_2\) concentrations up to 8 ppm in the gas phase and a maximum energy efficiency of 0.12 g/kWh are found. The experimental results are compared with a previously reported global chemical kinetics model and a one dimensional (1D) fluid model to investigate the chemical processes involved in \(\hbox {H}_2\hbox {O}_2\) production. An analytical balance of the main production and destruction mechanisms of \(\hbox {H}_2\hbox {O}_2\) is made which is refined by a comparison of the experimental data with a previously published global kinetic model and a 1D fluid model. In addition, the experiments are used to validate and refine the computational models. Accuracies of both model and experiment are discussed.     

Reactions of Unsaturated Quinoline Triosmium Clusters [Os3(CO)9(μ3-η2-C9H5(4-R)N)(μ-H)] (R=Me or H) with Tetramethylthiourea: X-ray Structures of [Os3(CO)8(μ-η2-C9H5(4-Me)N)(η2-SC(NMe2NCH2Me)(μ-H)2] and [Os3(CO)9(μ-η2-C9H6N)(η1-SC(NMe2)2)(μ-H)]

Treatment of the electronically unsaturated 4-methylquinoline triosmium cluster $[\hbox{Os}_{3}\hbox{(CO)}_{9}(\upmu_3\hbox{-}\upeta^{2}\hbox{-}\hbox{C}_{9}\hbox{H}_{5} \hbox{(4-Me)N})(\upmu\hbox{-H})]$ (1) with tetramethylthiourea in refluxing cyclohexane at 81°C gave $[\hbox{Os}_{3}\hbox{(CO)}_{8}(\upmu\hbox{-}\upeta^{2}\hbox{-C}_{9}\hbox{H}_{5} \hbox{(4-Me)N})(\upeta^2\hbox{-SC}(\hbox{NMe}_2\hbox{NCH}_2\hbox{Me})(\upmu \hbox{-H})_2]$ (2) and $[\hbox{Os}_{3}\hbox{(CO)}_{9}(\upmu\hbox{-}\upeta^{2}\hbox{-C}_{9}\hbox{H}_{5}\hbox{(4-Me)N})(\upeta^1\hbox{-SC}(\hbox{NMe}_2)_2)(\upmu\hbox{-H})]$ (3). In contrast, a similar reaction of the corresponding quinoline compound $[\hbox{Os}_{3}\hbox{(CO)}_{9}(\upmu_{3}\hbox{-}\upeta^{2}\hbox{-C}_{9}\hbox{H}_{6}\hbox{N})(\upmu\hbox{-H})]$ (4) with tetramethylthiourea afforded $[\hbox{Os}_{3}\hbox{(CO)}_{9}(\upmu\hbox{-}\upeta^{2}\hbox{-C}_{9}\hbox{H}_{6}\hbox{N})(\upeta^{1}\hbox{-SC(NMe}_{2})_{2})(\upmu\hbox{-H)}]$ (5) as the only product. Compound 2 contains a cyclometallated tetramethylthiourea ligand which is chelating at the rear osmium atom and a quinolyl ligand coordinated to the Os₃ triangle via the nitrogen lone pair and the C(8) atom of the carbocyclic ring. In 3 and 5, the tetramethylthiourea ligand is coordinated at an equatorial site of the osmium atom, which is also bound to the carbon atom of the quinolyl ligand. Compounds 3 and 5 react with PPh₃ at room temperature to give the previously reported phosphine substituted products $[\hbox{Os}_{3}\hbox{(CO)}_{9}(\upmu \hbox{-}\upeta^{2}\hbox{-C}_{9}\hbox{H}_{5}\hbox{(4-Me)N)(PPh}_{3})(\upmu\hbox{-H)}]$ (6) and $[\hbox{Os}_{3}\hbox{(CO}_{9}(\upmu \hbox{-}\upeta^{2}\hbox{-C}_{9}\hbox{H}_{6}\hbox{N)(PPh}_{3})(\upmu\hbox{-H)}]$ (7) by the displacement of the tetramethylthiourea ligand.