Surface Modification and Planar Defects of Calcium Carbonates by Magnetic Water Treatment

Powdery calcium carbonates, predominantly calcite and aragonite, with planar defects and cation–anion mixed surfaces as deposited on low-carbon steel by magnetic water treatment (MWT) were characterized by X-ray diffraction, electron microscopy, and vibration spectroscopy. Calcite were found to form faceted nanoparticles having 3x (0[`1] 1 4 0\bar{1} 1 4 ) commensurate superstructure and with well-developed {1 1[`2] 0 1 1\bar{2} 0 } and {10[`1] 4 10\bar{1} 4 } surfaces to exhibit preferred orientations. Aragonite occurred as laths having 3x (0[`1] 1 0\bar{1} 1) commensurate superstructure and with well-developed (0[`1] 1 0\bar{1} 1 ) surface extending along [100] direction up to micrometers in length. The (hkil)-specific coalescence of calcite and rapid lath growth of aragonite under the combined effects of Lorentz force and a precondensation event account for a beneficial larger particulate/colony size for the removal of the carbonate scale from the steel substrate. The coexisting magnetite particles have well-developed {011} surfaces regardless of MWT.     

Synthesis and characterization of water-based poly(vinyl acetate-co-butyl acrylate) latexes containing oligomeric protective colloid

Poly(vinyl acetate-co-butyl acrylate) latexes having oligomeric N-methylol acrylamide were prepared by semi-continuous emulsion polymerization. The effects of new protective colloid and comonomer ratios on the physicochemical and colloidal properties of latexes were investigated. The changes in homopolymer and copolymer latexes were determined by measuring viscosity, particle size, molecular weight (MW), molecular weight distribution (MWD), and surface tension. [`(M)]<sub>n</sub> \bar{M}_{n} values of copolymer latexes were found to be lower than the MWs of the poly(vinyl acetate) and poly(butyl acrylate) homopolymers. In general, [`(M)]_n \bar{M}_{n} and [`(M)]_\textw \bar{M}_{\text{w}} values of copolymer latexes changed irregularly with increasing BuA ratio in the copolymer composition.     

Thermodynamic characterization of poly (caprolactonediol) by inverse gas chromatography

Specific retention volumes, V _g ⁰, were determined for 21 solute probes on poly (caprolactonediol) (PCLD) in the temperature range 323.15–403.15 K by inverse gas chromatography. The retention diagrams drawn between ln V _g ⁰ versus 1/T are linear for all the solutes since PCLD with ten repeating units in its chain behaving like a non polymeric material under the conditions applied. The stationary phase with melting temperature ~321 K is in the liquid state in the GC column over the temperature range studied and hence found to be suitable to determine infinite dilution partial molar thermodynamic properties of mixing for solutes on PCLD. The V _g ⁰ values have been used to calculate weight fraction activity coefficients Ω^∞ and Flory–Huggins interaction parameters, χ ₁₂^∞. The average partial molar enthalpy of solution, [`(\Updelta H)]<sub>1</sub><sup>S</sup> , \overline{\Updelta H}_{1}^{S} , and partial molar enthalpy of mixing, [`(\Updelta H)]₁^￥ , \overline{\Updelta H}_{1}^{\infty } , are calculated using V _g ⁰ and Ω^∞ respectively. The average molar enthalpy of vaporization ΔH ₁ ^V for solutes have been calculated using [`(\Updelta H)]<sub>1</sub><sup>￥</sup> \overline{\Updelta H}_{1}^{\infty } and [`(\Updelta H)]₁^S \overline{\Updelta H}_{1}^{S} values and compared with the literature values at 363.15 K which is the average column temperature. The partial molar entropy of mixing, [`(\Updelta S)]<sub>1</sub><sup>￥</sup> \overline{\Updelta S}_{1}^{\infty } calculated at 363.15 K are in good correlation with the average [`(\Updelta H)]₁^￥ \overline{\Updelta H}_{1}^{\infty } values. The total solubility parameter due to Guillet and the Hansen solubility parameters (HSP) are calculated for PCLD using χ ₁₂^∞ values. In the present work the Hansen solubility parameters have been calculated using a new method following the Hansen theory and Huang method with less weight on polar and hydrogen bonding components. The errors in the solubility HSP are lower and the correlation coefficients are better in both the methods compared to unweighted three dimensional model.     

Transformation of the crystal structure in the series of K1 ? xCsxBSi2O6 borosilicate solid solutions

The transformation of the crystal structure by isomorphous K⁺-Cs⁺ substitutions in the non-tetrahedral positions leading to the phase transition has been studied in the series of K_{1 − x} Cs _x BSi₂O₆ solid solutions. The samples have been crystallized from the glass at 850°C for 10 h. According to the data on the crystal structures refined by the Rietveld method, the compositions with 0 ≤ x ≤ 0.35 crystallize in space group I[`4]3dI\bar 43d, structural type KBSi<sub>2</sub>O<sub>6</sub>, and those with 0.37 ≤ x ≤ 1.0, crystallize in Ia[`3]dIa\bar 3d, structural type CsBSi₂O₆. The reversible cubic-cubic phase transition I[`4]3d \rightleftarrows Ia[`3]dI\bar 43d \rightleftarrows Ia\bar 3d occurs in the composition range x = 0.35–0.37.     

Structure and Spectral Characteristics of 3D-Supramolecular Coordination Polymers Based on Copper Cyanide and Dimethylquinoxaline

The reactions of K₃[Cu(CN)₄], R₃SnCl (R = Me or ph) and 2,3-dimethyl quinoxaline (dmqox) in H₂O/acetonitrile media at room temperature afford the 3D-supramolecular coordination polymers (SCP) ³_￥ [ \textCu ₂ ( \textCN ) ₂ \textdmqox ] ^{ 3}_{\infty } \left[ {{\text{Cu}}_{ 2} \left( {\text{CN}} \right)_{ 2} {\text{dmqox}}} \right] , 1 and ³_￥ [ \textCu ₂ ( \textCN ) ₄ ·( \textPh ₃ \textSn ) ₂ ·\textdmqox ] ^{ 3}_{\infty } \left[ {{\text{Cu}}_{ 2} \left( {\text{CN}} \right)_{ 4} \cdot \left( {{\text{Ph}}_{ 3} {\text{Sn}}} \right)_{ 2} \cdot {\text{dmqox}}} \right] , 2. The structure of the tin free 1 consists of parallel zigzag chains connected by dmqox to form 2D-sheets containing hexagonal 18-atom fused Cu₆(CN)₄(dmqox)₂ rings. The interwoven sheets along the a axis are close packed by extensive H-bonds developing 3D-network structure. The structures of 1 and 2 are investigated by elemental analysis IR, NMR and mass spectra. The ESI⁺ and ESI⁻ mass spectra of 2 support its polymeric nature while the ESI⁺ mass spectrum confirms the expected M. W. suggested by elemental analysis. The ¹³C-NMR spectrum of 2 supports the fact that the network structure of 2 contains the rhombic [Cu₂(μ₃-CN)₂] motif. The structure of 2 was compared with the structure of the reported prototype ³_￥ [ \textCu ₂ ( \textCN ) ₄ ·( \textPh ₃ \textSn ) ₂ ·\textqox ] ^{ 3}_{\infty } \left[ {{\text{Cu}}_{ 2} \left( {\text{CN}} \right)_{ 4} \cdot \left( {{\text{Ph}}_{ 3} {\text{Sn}}} \right)_{ 2} \cdot {\text{qox}}} \right] as well as the other related structures.     

Nonlinear Rheology of Unentangled Polymer Melts Reinforced with High Concentration of Rigid Nanoparticles

A scaling model is presented to analyze the nonlinear rheology of unentangled polymer melts filled with high concentration of small spherical particles. Assuming the majority of chains to be reversibly adsorbed to the surface of the particles, we show that the emergence of nonlinearity in the viscoelastic response of the composite system subjected to a 2D shear flow results from stretching of the adsorbed chains and increasing desorption rate of the adsorbed segments due to the imposed deformation. The steady-state shear viscosity of the mixture in nonlinear shear thinning regime follows the power law h ~ [(g)\dot] ^{- 1/2} , \eta \sim \dot{\gamma }^{ - 1/2} , where [(g)\dot] \dot{\gamma } is the applied shear rate. At large strain amplitude γ_0, the storage and loss moduli in strain sweep tests scale as G^￠ ~ g₀ ^{- 1} G^{\prime}\sim \gamma_{0}^{ - 1} and G^￠￠ ~ g₀ ^{- 1/2} , G^{\prime\prime}\sim \gamma_{0}^{ - 1/2} , respectively.     

Effect of length of branched-chain of PAA-g-MPEO on dispersion of CaCO3 aqueous suspensions

The viscosity of CaCO₃/poly(acrylic acid) grafted methoxyl poly(ethylene oxide) (PAA-g-MPEO) aqueous suspensions was influenced by length of the branched-chain and content of PAA-g-MPEO. The viscosity of CaCO₃/PAA-g-MPEO suspensions first decreased and then increased with increasing length of branched-chain of PAA-g-MPEO at the same PAA-g-MPEO content. The viscosity of CaCO₃ suspensions containing PAA-g-MPEO with short branched-chain ([`(M)]<sub>n</sub> \bar{M}_{n}  = 200 g/mol and 600 g/mol) decreased with increasing the PAA-g-MPEO content. However, the viscosity of CaCO<sub>3</sub> suspensions containing PAA-g-MPEO with long branched-chain ([`(M)]_n \bar{M}_{n}  = 1500 g/mol) increased with increasing the PAA-g-MPEO content. The size distribution of CaCO₃ particles in CaCO₃ suspensions containing PAA-g-MPEO with the short branched-chain became narrower and the average size decreased with increasing length of the branched-chain. This is due to the steric hindrance of branched-chain of the PAA-g-MPEO adsorbing on surface of the CaCO₃ particles increased with increasing length of the branched-chain. The size distribution of CaCO₃ particles in CaCO₃ suspensions containing PAA-g-MPEO with the long branched-chain had two regions, and the average size increased compared with that of CaCO₃ particles in the CaCO₃ suspensions containing PAA-g-MPEO with the short branched-chain. This is due to the flocculation of fractional CaCO₃ particles induced by “tangle” between the long branched-chain of PAA-g-MPEO adsorbing on surface of CaCO₃ particles.     

Synthesis and Characterization of Crystalline Silicon Carbide Nanoribbons

In this paper, a simple method to synthesize silicon carbide (SiC) nanoribbons is presented. Silicon powder and carbon black powder placed in a horizontal tube furnace were exposed to temperatures ranging from 1,250 to 1,500°C for 5–12 h in an argon atmosphere at atmospheric pressure. The resulting SiC nanoribbons were tens to hundreds of microns in length, a few microns in width and tens of nanometers in thickness. The nanoribbons were characterized with electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy, and were found to be hexagonal wurtzite–type SiC (2H-SiC) with a growth direction of [10[`1]0] [10\bar{1}0] . The influence of the synthesis conditions such as the reaction temperature, reaction duration and chamber pressure on the growth of the SiC nanomaterial was investigated. A vapor–solid reaction dominated nanoribbon growth mechanism was discussed.     

Tapered ZnO Whiskers: {hkil}-Specific Mosaic Twinning VLS Growth from a Partially Molten Bottom Source

Zn particulates overlaid with wurtzite (W)-type ZnO condensates having nearly orthogonal and facets were found to self-catalyze unusual tapered W-ZnO whiskers upon isothermal atmospheric annealing, i.e., thermal oxidation, at 600 °C. Analytical electron microscopic observations indicated that such whiskers formed tapered slabs having mosaic and twinned domains. The tapered whiskers can be rationalized by an alternative vapor–liquid–solid growth, i.e., {hkil}-specific coalescence twinning growth from the ZnO condensates taking advantage of a partially molten bottom source of Zn and the adsorption of atoms at the whisker tips and ledges under the influence of capillarity effect. The tapered whiskers having strong photoluminescence at 391 nm and with a considerable flexibility could have potential applications.     

Heat stable and organosoluble polyimides containing laterally-attached phenoxy phenylene groups

In this research a diamine monomer containing two phenoxy phenylene lateral groups, 2,2′-bis[(p-phenoxy phenyl)]-4,4′-diaminodiphenyl ether (PPAPE) was used to prepare novel wholly aromatic polyimides by thermal or chemical two-step polycondensation reactions. Comonomers including pyromellitic dianhydride (PMDA), 4,4′-oxydiphthalic anhydride (ODPA), and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) were used for the polyimidization reactions. A reference polyimide was also prepared by the reaction of 4,4′-diaminodiphenyl ether (DADPE) with pyromellitic dianhydride (PMDA). The limited viscosity numbers as well as [`(M)]<sub>n</sub> \overline{M}_n and [`(M)]_w \overline{M}_w values of the resulting polymers were determined. All PPAPE-resulted polyimides had excellent organosolubility in common polar solvents. A low crystallinity extent was only observed using their wide-angle X-ray diffractograms (WAXD). The prepared hinged polyimides could also be cast into transparent and flexible films. The glass transition temperatures of the resulting polyimides were determined by differential scanning calorimetry (DSC) analyses. The thermograms obtained from thermogravimetric analyses (TGA) showed that the phenoxy phenylene lateral groups attached to the macromolecular backbones had no substantial diminishing effect on the thermal stability of these structurally-modified polyimides.     

Two New Organic–Inorganic Hybrids Based on [SiW12O40]4? Anion: Hydrothermal Syntheses, Crystal Structures, and Electrochemical Properties

Two new organic–inorganic hybrid compounds [\textCu^\textI ( \texten ) ₂ ( \textH ₂ \textO )] ₂ { ( \textSiW^\textVI _{1 1} \textW^\textV ₁\textO ₄₀ ) ₂ [ \textCu^\textII ( \texten ) ₂ ( \textH ₂ \textO )] ₂ [\textCu^\textII ( \texten ) ₂ ] ₂ }·6 \textH ₂ \textO [{\text{Cu}}^{\text{I}} \left( {\text{en}} \right)_{ 2} \left( {{\text{H}}_{ 2} {\text{O}}} \right)]_{ 2} \left\{ {\left( {{\text{SiW}}^{\text{VI}}_{ 1 1} {\text{W}}^{\text{V}}_{ 1}{\text{O}}_{ 40} } \right)_{ 2} \left[ {{\text{Cu}}^{\text{II}} \left( {\text{en}} \right)_{ 2} \left( {{\text{H}}_{ 2} {\text{O}}} \right)\left] {_{ 2} } \right[{\text{Cu}}^{\text{II}} \left( {\text{en}} \right)_{ 2} } \right]_{ 2} } \right\}{\cdot}6 {\text{H}}_{ 2} {\text{O}} (1) and (H₂ L)₂[SiW₁₂O₄₀]·H₂O (2) [en = ethylenediamine, L = 1,4-bis(3-pyridinecarboxamido)benzene], have been hydrothermally synthesized and characterized by IR, elemental analyses, TG analysis, and single-crystal X-ray diffraction. Structural analyses indicate that compound 1 exhibits an interesting three-dimensional(3D) cross-like supramolecular network through arrangement of a 1D organic–inorganic hybrid chain { ( \textSiW^\textVI _{1 1} \textW^\textV ₁ \textO ₄₀ ) ₂ [ \textCu^\textII ( \texten ) ₂ ( \textH ₂ \textO )] ₂ [\textCu^\textII ( \texten ) ₂ ] ₂ } ^2- . \left\{ {\left( {{\text{SiW}}^{\text{VI}}_{ 1 1} {\text{W}}^{\text{V}}_{ 1} {\text{O}}_{ 40} } \right)_{ 2} \left[ {{\text{Cu}}^{\text{II}} \left( {\text{en}} \right)_{ 2} \left( {{\text{H}}_{ 2} {\text{O}}} \right)\left] {_{ 2} } \right[{\text{Cu}}^{\text{II}} \left( {\text{en}} \right)_{ 2} } \right]_{ 2} } \right\}^{ 2- } . The compound 2 consists of protonated L ligand and [SiW₁₂O₄₀]⁴⁻ anion. The protonated L ligands have been extended into a 2D network via hydrogen-bonding interactions. The guest [SiW₁₂O₄₀]⁴⁻ clusters have been incorporated into the square voids of the 2D host network as templates. The electrochemical behavior and electrocatalysis of compound 2 bulk-modified carbon paste electrode (2-CPE) have been studied.     

Catalytic, Luminescence Activities and Structure of Metal-Organic Frameworks Containing CuCN Building Blocks and Bipodal Bridging Ligands

The reactions of K₃[Cu(CN)₄], R₃SnCl and bipodal ligands, where R = (n-Bu)₃SnCl and L = quinoxaline (qox) and R = Me₃SnCl and L = quinazoline (qaz) afford the red needle crystals of _￥³ [ \textCu₂ ( \textCN )₂ m\text-(qox) ]₂ {}_{\infty }^{3} \left[ {{\text{Cu}}_{2} \left( {\text{CN}} \right)_{2} \mu {\text{-(qox)}}} \right]_{2} , 1 and the orange needle crystals of [Cu₂(CN)₂μ(qaz)]_n, 2. 1 was subjected to single crystals X-ray study while 2 was investigated by IR, ¹H NMR and mass spectra as well as TGA. The crystal structure of 1 exhibits puckered CuCN chains connected by qox molecules forming 2D-sheets. The 2D-sheets contain hexagonal nets stacked in A···A···A fashion. The paralleled sheets are close packed via extensive H-bonds, π–π stacking, strong Cu-Cu interaction and short Cu–C contacts which develop 3D-network. Unique rhombic [Cu₂(μ₃-CN)₂] motifs result as consequence of interwoven of the 2D-sheets. The structure of 2 exhibits different XRPD pattern than that of 1 although, the two structures have the same Cu:CN:L stoichiometric ratio. The emission spectra of 1 and 2 display bands around 390, 420 and 475 nm corresponding to MC transition, ¹(n,π*) → S_o and MLCT, respectively. Thus, 1 and 2 can be considered as examples of room-temperature luminescent Cu-containing polymers which can be used in applications as molecular sensing systems. Also, the oxidative degradation of Metanil Yellow (MY) dye has been investigated by hydrogen peroxide catalyzed by 1 or 2. The catalytic activity of 1 is more pronounced than that of 2.     

Fe-doping effects on the structural and electrochemical properties of 0.5Li<Subscript>2</Subscript>MnO<Subscript>3</Subscript>·0.5LiMn<Subscript>0.5</Subscript>Ni<Subscript>0.5</Subscript>O<Subscript>2</Subscript> electrode material

With the aim of achieving a high-performance 0.5Li₂MnO₃·0.5LiMn_0.5Ni_0.5O₂ material, a series of 0.5Li₂MnO₃·0.5LiMn _x Ni _y Fe_(1−x−y)O₂ (0.3 ≤ x ≤ 0.5, 0.4 ≤ y ≤ 0.5) samples with low Fe content was synthesized via coprecipitation of carbonates. Its crystal structure and electrochemical performance were characterized by means of powder X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, galvanostatic charge/discharge testing, cyclic voltammetry, and electrochemical impedance spectra. Rietveld refinements with a model integrating R [`3] \overline{3} m and Fm [`3] \overline{3} m indicate that a low concentration of Fe incorporated in 0.5Li₂MnO₃·0.5LiMn_0.5Ni_0.5O₂ decrease a disordered cubic domain of the composite structure. The preferential distribution of Fe in cubic rock-salt contributes to an unimaginable decrease of c-axis parameter of the predominant layered structure as the Fe content increases. Moreover, including Fe as a dopant can kinetically improve crystallization and also change the ratio of Mn³⁺/Mn⁴⁺ and Ni³⁺/Ni²⁺. As a result, 0.5Li₂MnO₃·0.5LiMn_0.4Ni_0.5Fe_0.1O₂ exhibits lower Warburg impedance and higher reversible capacity than the undoped material.     

Functionalization of cotton fabric orienting towards antibacterial activity

The primary objective of modifying cotton fabric was to impart bactericidal properties to attract various fields such as defence, space and textile industrial applications. Chemically initiated graft copolymerization of 4-vinyl pyridine (4-VP) and acrylonitrile (AN) onto cotton fabric was carried out using ceric ammonium nitrate as a redox initiator. Optimum conditions pertaining to maximum percentage of grafting were evaluated as a function of concentration of initiator [CAN], concentration of nitric acid, monomer concentration, water, temperature and reaction time. Maximum grafting of 4-VP (51.63%) and AN (69.23%) was obtained respectively at optimum [ \textCAN ] = 2.738 ×10 ^{- 2} \left[ {\text{CAN}} \right] = 2.738 \times {10^{ - 2}} and 2.19 × 10⁻² moles/L, [ 4 - \textVP ] = 47.55 ×10 ^{- 22}\textmoles/\textL \left[ {4 - {\text{VP}}} \right] = 47.55 \times {10^{ - 22}}{\text{moles}}/{\text{L}} , [ \textAN ] = 18.85 ×10 ^{- 22}\textmoles/\textL \left[ {\text{AN}} \right] = 18.85 \times {10^{ - 22}}{\text{moles}}/{\text{L}} , [ \textHN\textO₃ ] = 11.9 ×10 ^{- 2} \left[ {{\text{HN}}{{\text{O}}_3}} \right] = 11.9 \times {10^{ - 2}} and 89.5 × 10⁻²² moles/L in 20 and 25 ml of water at an optimum temperature 70 °C and 60 °C with in 180 and 120 min. Antibacterial properties were induced into the modified cotton fabric by treating the grafted fabric with benzyl chloride. The grafted and quaternized copolymer were characterized by FTIR and Thermogravimetrical analysis. The bactericidal action of cotton fabric was tested by filtration test and it was observed that fabric grafted with 4-VP was more effective and efficient antibacterial as compared to AN grafted cotton sample.     

Intrinsic viscosity-number average molecular weight relationship for poly (n-Octadecyl acrylate) and poly (N-n-octadecylacrylamide)

Intrinsic viscosity-number average molecular weight relationships have been measured, at 30C in benzene, for poly (n-octadecyl acrylate) as [η]=2.72×10⁻⁴ Mn^0.638 and for poly (N-n-octadecylacrylamide) as [η]=0.82×10⁻⁴ Mn^0.676. Whole polymers of various molecular weights were prepared in benzene solution at 65C with dodecyl mercaptan as primary regulator. By the use of these parameters, the molecular weight of such polymers and their homologs may now be measured by simple solution-viscosity determinations. In the expression { } (relating degrees of polymerization { } to the mercaptan/monomer ratio), intercept { } and apparent transfer constant C_s for n-octadecyl acrylate were 6.28×10⁻³ and 0.68; for N-n-octadecylacrylamide 1.10×10⁻³ and 0.62 respectively. These parameters permit preparation of homopolymers of chosen molecular weight. Presented at the AOCS Meeting, Philadelphia, October 1966 E. Utiliz. Res. Devel. Div., ARS, USDA.     

An efficient and nonflammable organic phosphate electrolyte for dye-sensitized solar cells

A new fire-retardant, diethyl ethyl phosphate (DEEP), was tested as a nonflammable electrolyte solvent for dye-sensitized solar cells (DSSCs). Electrochemical measurements demonstrated that the DEEP electrolyte has a wide potential window (>5 V), sufficient ionic conductivity (3.5 × 10⁻³ S cm⁻¹ at 25 °C), and electrochemical activity for the I ^- /I₃ ^- I^{ - } /I_{3}^{ - } redox couple. The DEEP-based DSSCs exhibited an open circuit voltage of 0.72 V, short circuit photocurrent of 10.45 mA cm⁻², and a light-to-electricity conversion efficiency of 4.53%, which are almost the same as those observed from the DSSCs using currently optimized organic carbonate electrolytes. Meanwhile, the long-term stability of the DSSCs was greatly improved with the use of the DEEP electrolyte, showing a potential application of this new electrolyte for the construction of efficient, stable, and nonflammable DSSCs.     

Mass transfer from outer surface of thin tubes in parallel turbulent flow

The mass transfer coefficients from the outer surface of tubes or cylinders held in parallel turbulent steams have been calculated using integral momentum and mass transfer equations. The solution uses a hydrodynamics independent constant, λ _c which depends only upon Schmidt number. The results exhibit significant effect of curvature. For Schmidt number less than 108, Sherwood number can be predicted by $Sh_d Sc^{ - 1/3} = 0.039Sc^{0.208} \times \left( {\frac{L} {d}} \right)^\alpha \operatorname{Re} _d^{0.8}$Sh_d Sc^{ - 1/3} = 0.039Sc^{0.208} \times \left( {\frac{L} {d}} \right)^\alpha \operatorname{Re} _d^{0.8}, where α = −0.169Sc^−0.0103. The effect of the curvature is insignificant where $\frac{L} {d}\operatorname{Re} _L^{ - 0.2} - 0.033 \times \ln (Sc) \leqslant 0.214$\frac{L} {d}\operatorname{Re} _L^{ - 0.2} - 0.033 \times \ln (Sc) \leqslant 0.214.     

Binding Energy and Spin-Orbit Splitting of a Hydrogenic Donor Impurity in AlGaN/GaN Triangle-Shaped Potential Quantum Well

In the framework of effective-mass envelope function theory, including the effect of Rashba spin-orbit coupling, the binding energy E _b and spin-orbit split energy Г of the ground state of a hydrogenic donor impurity in AlGaN/GaN triangle-shaped potential heterointerface are calculated. We find that with the electric field of the heterojunction increasing, (1) the effective width of quantum well [`(\textW)] \overline{\text{W}} decreases and (2) the binding energy increases monotonously, and in the mean time, (3) the spin-orbit split energy Г decreases drastically. (4) The maximum of Г is 1.22 meV when the electric field of heterointerface is 1 MV/cm.     

Conduction in Bi2O3-based oxide ion conductor under low oxygen pressure. II. Determination of the partial electronic conductivity

In order to investigate the partial electronic conduction in the high oxide ion conductor of the system Bi₂O₃-Y₂O₃ under low oxygen pressure, e.m.f. and polarization methods were employed. Although the electrolyte was decomposed when the \(P_{{\text{O}}_{\text{2}} }\) was lower than the equilibrium \(P_{{\text{O}}_{\text{2}} }\) of Bi, Bi₂O₃ mixture at each temperature, the ionic transport number was found to be close to unity above that \(P_{{\text{O}}_{\text{2}} }\) . The hole conductivity (σ _p) and the electron conductivity (σ _p) could be expressed as follows, $$\begin{gathered} \sigma _p \Omega cm = 5 \cdot 0 \times 10^2 \left( {P_{O_2 } atm^{ - 1} } \right)^{{1 \mathord{\left/ {\vphantom {1 4}} \right. \kern-\nulldelimiterspace} 4}} \exp \left[ { - 106 kJ\left( {RT mol} \right)^{ - 1} } \right] \hfill \\ \sigma _p \Omega cm = 3 \cdot 4 \times 10^5 \left( {P_{O_2 } atm^{ - 1} } \right)^{ - {1 \mathord{\left/ {\vphantom {1 4}} \right. \kern-\nulldelimiterspace} 4}} \exp \left[ { - 213 kJ\left( {RT mol} \right)^{ - 1} } \right] \hfill \\ \end{gathered} $$ These values were much lower than the oxide ion conductivity under ordinary oxygen pressure.     

Intrinsic kinetics of the Fischer-Tropsch synthesis over an impregnated cobalt-potassium catalyst

The optimal amount of 15 wt%Co/10 wt%K/Al₂O₃ catalyst was prepared using the impregnation technique in order to study the kinetics of the Fischer-Tropsch synthesis. The rate of synthesis was measured in a fixed-bed micro reactor with H₂/CO feed ratio of 1–3 and space velocity in the range of 2,700–5,200 h⁻¹ under reactor pressure of 8 bar and a temperature range of 210–240 °C. The experimental data were best fitted by a Langmuir-Hinshelwood-Hougen-Watson (LHHW) approach rate in the form of - r_CO = (k₂ K₁ P_CO P_H2 )/(1 + K₁ P_CO ) - r_{CO} = (k_2 K_1 P_{CO} P_{H_2 } )/(1 + K_1 P_{CO} ). Furthermore, the data were fitted fairly well by a power law equation in the form of - r_CO = kP_CO^1.32 P_H2 ^1.42 - r_{CO} = kP_{CO}^{1.32} P_{H_2 }^{1.42} . The activation energies for LHHW approach model and power law equation were obtained as 138.5 kJ/mol and 87.39 kJ/mol, respectively.