Good Straight Line Research Articles

Cinética de consumo de sustratos orgánicos de bacterias aisladas de la Laguna de Chascomus

Eight bacterial strains were isolated from Chascomús Pond (Buenos Aires Province) and their capacity to growth at low concentrations of glycolate and glucose, as a solé source of organic carbón was evaluated.Substrate affinities (Kt valúes) and other kinetic parameters were measured by Wright & Hobbie methodology with 14C-labelled glycollate and MC-labelled glucose as substrates. Four o f the eight puré culture studied followed Michaelis-Menten uptakekinetics giving good straight lines after the Lineweaver-Burke transfonnation.Vmax valúes o f natural popuiations and the experimental ones were similar for glycollate; for glucose the experimental valúes were a little higher. This suggest the possibility o f applying the experimental Kt valúes to natural popuiations as a way of evaluation o f the natural substrate concentration.

Is Hammett Correlation of Dipole Moments of <i>mono</i>-Substituted Benzenes Helpful to Distinguish <i>o,p</i>-Directing Groups from <i>m</i>-Directing Groups in an Aromatic Electrophilic Substitution? A Chemical Education Perspective

In chemistry literature it is so far achieved to distinguish o,p-directing groups from m-directing groups purely on the basis of only relative yields of ortho, para and meta electrophilic substituted products in the benzene ring and it is also based on their ability to disturb the pi-electron density at the carbons. It is for the first time in chemistry literature using dipole moment data a linear free energy relationship (LFER), Hammett equation is used to distinguish o,p-directing groups from m-directing groups. This could be achieved by constructing Hammett plots with dipole moments versus Hammett para substituent constants for electron donating groups and Hammett meta substituent constants for electron withdrawing groups. Good straight lines are obtained with correlation coefficients close to 0.9 with certainly an unmistakable trend.

The Electrophilicities of XCF3 and XCl (X=H, Cl, Br, I) and the Propensity of These Molecules To Form Hydrogen and Halogen Bonds with Lewis Bases: An Ab Initio Study.

Equilibrium dissociation energies, De , of four series of halogen- and hydrogen-bonded complexes B⋅⋅⋅XCF3 (X=H, Cl, Br and I) are calculated ab initio at the CCSD(T)(F12c)/cc-pVDZ-F12 level. The Lewis bases B involved are N2 , CO, PH3 , C2 H2 , C2 H4 , H2 S, HCN, H2 O and NH3 . Plots of De versus NB , where the NB are the nucleophilicities assigned to the Lewis bases previously, are good straight lines through the origin, as are those for the corresponding set of complexes B⋅⋅⋅XCl. The gradients of the De versus NB plots define the electrophilicities EXCF3 and EXCl of the various Lewis acids. The determined values are: EXCF3 =2.58(22), 1.40(9), 2.15(2) and 3.04(9) for X=H, Cl, Br and I, respectively, and EXCl =4.48(22), 2.31(9), 4.37(27) and 6.06(37) for the same order of X. Thus, it is found that, for a given X, the ratio EXCl / EXCF3 is 2 within the assessed errors, and therefore appears to be independent of the atom X and of the type of non-covalent interaction (hydrogen bond or different varieties of halogen bond) in which it is involved. Consideration of the molecular electrostatic surface potentials shows that De and the maximum positive electrostatic potential σmax (the most electrophilic region of XCF3 and XCl, which lies on the symmetry axes of these molecules, near to the atom X) are strongly correlated.

Mechanochemical effect on swelling and drug release of natural polymer matrix tablets by X-ray computed tomography

The relationships between the physicochemical properties of milled starch and drug release from tablets were investigated quantitatively using a drug release kinetic method and X-ray computed tomography (XCT). The samples were prepared from raw β-starch by milling in a planetary ball mill. The tablets, containing 5% theophylline (TH), 94% milled starch, and 1% magnesium stearate, were compressed at 6 kN. The drug-release and gel-forming processes were measured simultaneously using an original dissolution tester with an XCT instrument. Drug release from the tablet was delayed with increasing milling time, because the TH tablet formed a typical gel-layer on the outside of the tablet. The relationship between the crystallinity of milled starch and mean drug release time (MDT) for the TH tablets showed almost a straight inverse proportional relationship. The plots of MDT against area under the curve of the swelling ratio profiles of the TH tablets had a good straight line.

Kinetics of water vapor adsorption by vacuum-dried jujube powder

Water vapor adsorption kinetics of vacuum-dried jujube powder were investigated in temperature and relative humidity ranges of 10 to 40℃ and 32 to 75%, respectively. Water vapor was initially adsorbed rapidly and then reached equilibrium condition slowly. Reaction rate constant for water vapor adsorption of vacuum-dried jujube powder increased with an increase in temperature. The temperature dependency of water activity followed the Clausius-Clapeyron equation. The net isosteric heat of sorption increased with an increase in water activity. Good straight lines were obtained with plotting of 1/(m-m0) vs. 1/t. It was found that water vapor adsorption kinetics of vacuum-dried jujube powder was accurately described by a simple empirical model, and temperature dependency of the reaction rate constant followed the Arrhenius-type equation. The activation energy ranged from 50.90 to 56.00 kJ/mol depending on relative humidity. Arrhenius kinetic parameters (Ea and k0) for water vapor adsorption by vacuum-dried jujube powder showed an effect between the parameters with the isokinetic temperature of 302.51 K. The information on water vapor adsorption kinetics of vacuum-dried jujube powder can be used to establish the optimum condition for storage and processing of jujube.

Arrhenius Variation of Precipitation Time for VV in Vanadium Flow Batteries

Both visual observation and light-scattering measurements were used to investigate the stability of typical vanadium flow battery (VFB) catholytes. V2O5 precipitates after an induction time that decreases with increasing temperature and concentration of VV and increases with concentration of sulphate. This was observed at 30-60°C for VV and sulphate concentrations of 1.4–2.11 and 3.7–5.3 mol dm-3, respectively. Arrhenius plots of induction time show excellent linearity and the logarithm of induction time varies linearly with both sulphate and VV concentration. An Arrhenius plot of induction times normalized to standard reference concentrations of sulphate and VV for all solutions gave a good straight line. The activation energy estimated from the slope is E# = 1.79 eV. Combining the Arrhenius Equation and the observed variation with sulphate and VV concentrations, an equation was derived which enables us to simulate the induction time for any catholyte solution at any temperature in the range investigated.

Effects of Temperature and Composition on Catholyte Stability in Vanadium Flow Batteries: Measurement and Modeling

The stability of typical vanadium flow battery (VFB) catholytes was investigated at temperatures in the range 30–60°C for VV concentrations of 1.4–2.2 mol dm−3 and sulfate concentrations of 3.6–5.4 mol dm−3. In all cases, V2O5 precipitates after an induction time, which decreases with increasing temperature. Plots of the logarithm of induction time versus the inverse of temperature (equivalent to Arrhenius plots) show excellent linearity and all have similar slopes. The logarithm of induction time also increases linearly with sulfate concentration and decreases linearly with VV concentration. The slopes of these plots give values of concentration coefficients βS and βV5 which were used to normalize induction times to reference concentrations of sulfate and VV. An Arrhenius plot of the normalized induction times gives a good straight line, the slope of which yields a value of 1.791 ± 0.020 eV for the activation energy. Combining the Arrhenius equation with the observed variation with sulfate and VV concentrations, an equation was derived for the induction time for any catholyte at any temperature in the range investigated. Although the mechanism of precipitation of VV from catholytes is not yet well understood, a precise activation energy can now be assigned to the induction process.

Correlation between the photocatalysed oxidation of methylene blue in solution and the reduction of resazurin in a photocatalyst activity indicator ink (Rz Paii )

Abstract The initial rate of the photocatalysed oxidation of methylene blue, MB, by dissolved oxygen in solution, ri(MB), is measured for a series of titania on glass samples exhibiting a wide range of activities. The samples used include two different types of commercial self-cleaning glass and a lab-made sol-gel titania film. The activities of these samples are also assessed using a resazurin-based photocatalyst activity indicator ink, i.e. Rz paii, for which the initial rates of the photocatalysed reduction of Rz were measured, ri(Rz). A plot of ri(MB) vs. ri(Rz) reveals a good straight line, thereby demonstrating a linear correlation (for TiO2 films on glass at least) between the slow (usually hours) photocatalysed oxidation of organic materials, such as MB, and the fast (typically min) photocatalysed irreversible reduction of a dye, like Rz, in a paii. The possible use of paii technology for assessing, in a simple, quick and inexpensive manner, photocatalytic films both in the laboratory and in situ is discussed briefly.

シンクロトロン蛍光X線分析法による世界文化遺産三重津海軍所跡（佐賀市）出土磁器の胎土分析 ─第1報，陶石，佐賀城跡出土磁器との比較─

A lot of porcelains were found at the Mietsu Naval Facility Site in Saga, Japan, which was approved as a World Heritage by UNESCO in July, 2015. We determined the X-ray fluorescence intensity ratios of Fe, Rb, Sr, Y and Zr involved in the body clay of the porcelains by synchrotron X-ray fluorescence analysis, and compared them with those excavated from the Saga castle site and with Amakusa or Izumiyama porcelain stones. The X-ray fluorescence intensity ratio of each element was the highest for Fe in all samples, but other chemical elements depended on the kind of porcelain and the porcelain stone. Sr was the lowest for porcelain stones, but increased greatly for porcelains. A plot of log {Intensity ratio (Rb/Sr)} vs. log {Intensity ratio (Zr/Sr)} gave a good straight line. The data for the porcelain stones gathered in the 1st quadrant and those of the porcelains of the Saga castle site shifted a little to the left lower side, but those of porcelains of the Mietsu Naval Facility site shifted to the more left and lower side. The change in the intensity ratio of elements was ascribed to the porcelain stones used and to the manufacturing process of the clay.

Study on thermodynamic property for ionic liquid [C4mim][Lact](1-butyl-3-methylimidazolium lactic acid)

Lactic acid ionic liquid [C4mim][Lact] (1-butyl-3-methylimidazolium lactic acid) was synthesized by the neutralization method. Using the solution–reaction isoperibol calorimeter, the molar enthalpies of solution, ΔsolHm, with different molalities were determined in the temperature range from (288.15 to 308.15 ± 0.01) K with an interval of 5 K. In terms of Archer’s method, the standard molar enthalpy of solution for [C4mim][Lact], \( \Delta _{\text{sol}} H_{\text{m}}^{\theta } \), was obtained, and then, the values of apparent relative molar enthalpy, ΦL, and the Pitzer’s parameters \( \beta_{\text{MX}}^{(0)\text{L}} \) and \( \beta_{\text{MX}}^{(1)\text{L}} \) were determined for [C4mim][Lact]. The plot of \( \Delta _{\text{sol}} H_{\text{m}}^{\theta } \) versus (T—298.15) K is a good straight line, and its slope is the standard molar heat capacity of solution, \( \Delta C_{\text{p,m}}^{\theta } = 240\,{\text{J}}\,{\text{K}}^{ - 1} \). According to Glasser’s theory of lattice energy, the hydration enthalpy of cation and anion, (ΔH+ + ΔH−) = −471 kJ mol−1, in infinite dilution and the hydration enthalpy of anion, ΔH−([Lact]−) = −257 kJ mol−1, were obtained at 298.15 K. The heat capacity of aqueous [C4mim][Lact], Cp(sol), and the apparent molar heat capacity, ΦCp, of various specific molalities were also obtained.

Determination of the Molar Enthalpy of Solution for Ionic Liquid [C5mim][OAc](1-pentyl-3-methylimidazolium acetate) in the Temperature Range from 288.15 to 308.15 K

The molar enthalpies of solution, ΔsolHm, for ionic liquid [C5mim][OAc] with different molalities were measured by the solution-reaction isoperibol calorimeter in the temperature range from 288.15 to 308.15 K with an interval of 5 K. According to Archer’s method, the standard molar enthalpies of solution, ΔsolHmθ, and the apparent relative molar enthalpy, ΦL, for [C5mim][OAc] were determined. In terms of Glasser’s theory of lattice energy, the hydration enthalpy of the cation, ΔH+ ([C5mim]+) = −178 kJ·mol–1 was obtained at 298.15 K. Compared with hydration enthalpy of [C2mim]+, ΔH+ ([C2mim]+) = −233 kJ·mol–1, the hydration of [C5mim]+ is weaker than [C2mim]+. The plot of ΔsolHmθ vs (T – 298.15) K is a good straight line and its slope is the standard molar heat capacity of solution, ΔCp,mθ = 231 J·K–1·mol–1, so that the specific heat capacity of solution, ΔCpθ = 1.09 J·g–1·K–1, was obtained for IL [C5mim][OAc].

Moisture sorption isotherms and thermodynamic properties of Jack pine and palm wood: Comparative study

Currently, the impact of the controlled climate on moisture sorption isotherms of Jack pine and palm wood still remains unclear. The aim of this paper was to determine and compare the moisture sorption isotherms and thermodynamic properties of Jack pine and palm wood. The equilibrium moisture content of wood samples was measured within the range of 5 to 90% relative humidity at 50°C, 60°C, 70°C and 80°C. For both wood varieties, the equilibrium moisture content decreased with increasing temperature, however the effect of temperature is very remarkable for palm wood. The isosteric heat of desorption, the enthalpy and the entropy decreased with the increase of the moisture content. A good straight line correlated differential enthalpy and entropy, according to the enthalpy–entropy compensation theory. The spreading pressure decreased with increasing temperature at a given water activity, and increased with increasing water activity at a constant temperature. Predictive correlations of the two wood properties, based on experimental methods and physical laws, were established and compared.

Kinetics of alkaline hydrolysis of p‐substituted benzylidenemalononitriles in 50% aqueous acetonitrile: substituent effects and quantification of the electrophilic reactivity

The rate constants of the reaction of p‐X‐substituted benzylidenemalononitriles 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h with hydroxide ion were measured in 50% water–50% acetonitrile at 20 °C. The experimental kinetic data reveal that the points pertaining to electron donating substituted compounds (X = Me, OMe and NMe2) exhibit negative deviations from the Hammett plot. However, the Yukawa–Tsuno plot for the same rate constants resulted in a good straight line with an excellent correlation coefficient (r2 = 0.9916) and an r value of 1.15. Possible ground‐state stabilization through resonance interactions has been suggested to explain the origin of the nonlinear Hammett plot. On the basis of the relationship between E and σp+, the electrophilicity parameter E of some benzylidenemalononitriles 1c and 1e, 1f, 1g, 1h has been evaluated. More importantly, the three compounds 1f (E = −7.90), 1g (E = −7.80) and 1h (E = −7.55) exhibit high electrophilicities that compare well with that of 4,6‐dinitrobenzoselenadiazole (E = −7.40), a compound which has a general behaviour representative for the superelectrophilic dimension. We have shown that the second‐order rate constants calculated from Mayr's approach for the reaction of 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h with hydroxide ion do not agree with the available experimental data. On the other hand, a good linear correlation between log kexp and log kcalc has been observed and discussed. Copyright © 2014 John Wiley & Sons, Ltd.

High-Resolution Rovibrational Spectroscopy of Carbon Monoxide Isotopologues Isolated in Solid Parahydrogen

We report high-resolution infrared absorption spectra of six different CO isotopologues isolated in cryogenic parahydrogen (pH2) solids. These data provide a stringent test for theories of nearly free molecular rotors in crystalline solids, such as crystal field theory, rotation-translation coupling theory, and the pseudorotating cage model. A gas-phase molecule rotates about its center-of-mass (C.M.); a trapped molecule instead rotates about its "center of interaction" (C.I.) with the trapping cage, which may differ from the C.M. for heteronuclear diatomics like CO. Isotopic manipulation of CO allows the systematic variation of the C.M. relative to the C.I. We report remarkably good straight line correlation plots between the observed matrix effects and C.M. locations. Extrapolation of these lines to the limit of vanishing matrix effects yields an "experimental prediction" of the C.I. in excellent (fortuitous?) agreement with the C.I. calculated using a linear pH2-CO-pH2 toy model.

Study on enthalpy and molar heat capacity of solution for ionic liquid [C3mim][OAc](1-propyl-3-methylimidazolium acetate)

Using the solution–reaction isoperibol calorimeter, molar enthalpies of solution, ΔsolHm, for ionic liquid [C3mim][OAc] with different molalities were measured in the temperature range from (288.15 to 308.15±0.01)K with an interval of 5K. In terms of Archer’s method, the standard molar enthalpies of solution, ΔsolHmθ, for [C3mim][OAc] were obtained in the temperature range of (288.15 to 308.15±0.01)K. According to Glasser’s theory of lattice energy the hydration enthalpy of cation and anion in infinite dilution aqueous [C3mim][OAc], (ΔH++ΔH−)=−514kJ·mol−1, at 298.15K. Plotting the experimental values of ΔsolHmθ against ΔT, a good straight line was obtained and the slope of the line is the standard molar heat capacity of solution. ΔCp,mθ=200J·K−1·mol−1, for [C3mim][OAc] and the specific heat capacity of solution, ΔCpθ=1.09J·g−1·K−1, was also obtained. The contribution per methylene to the molar solution enthalpy ΔsolHmθ (−CH2−)=0.76kJ·mol−1 and the contribution from fitted values calculated for the temperature, ΔsolHmθ (−CH2−)=0.90kJ·mol−1, at 298.15K, they are approximately equal. The values of the standard molar heat capacity of solution, ΔCp,mθ, and the specific heat capacity of solution, ΔCpθ, decrease with the increase of chain of methylene (–CH2–) of [Cnmim][OAc] (n=2,3).

The Effects of Applied Stress and Test Temperature on the Environment-Induced Cracking Behavior of Carbon Steel in NH<sub>4</sub>NO<sub>3</sub> Solution

The effects of applied stress and test temperature on the environment-induced cracking (EIC) behavior of carbon steel in 5 kmol/m3 NH4NO3 solution were investigated by using constant load method. The three parameters (time to failure (tf), steady state elongation rate (lss) and transition time to time to failure ratio (tss/tf)) were obtained from a corrosion elongation curve. The relationships between applied stress and the three parameters were divided into three regions; the stress-dominated, the EIC-dominated and the corrosion-dominated regions. Under an applied stress of 225 MPa (in the EIC-dominated region), the test temperature dependences of the three parameters were investigated. Although tf decreased with increasing test temperature above 323 K, it became constant independent of test temperature under 323 K. Whenever the EIC takes place, the relationship between log tf and log lss become a good straight line with a slope of -1.1 irrespective applied stress and test temperature, which means that lss becomes a parameter for predicting tf. In addition, the fracture appearance in the EIC-dominated region was intergranular. From the results obtained, the intergranular cracking of carbon steel was discussed in terms of film formation, dissolution and hydrogen permeation.

Study on Enthalpy and Molar Heat Capacity of Solution for the Ionic Liquid [C2mim][OAc] (1-Ethyl-3-methylimidazolium acetate)

An acetic acid ionic liquid (AcAIL) [C2mim][OAc] (1-ethyl-3-methylimidazolium acetate) was prepared by the neutralization method. Using the solution-reaction isoperibol calorimeter, molar enthalpies of solution, ΔsolHm, for the ionic liquid [C2mim][OAc] with different molalities were measured in the temperature range from (288.15 to 308.15 ± 0.01) K with an interval of 5 K. In terms of Archer’s method, the standard molar enthalpies of solution, ΔsolHmθ, for [C2mim][OAc] were obtained in the temperature range of (288.15 to 308.15 ± 0.01) K. Plotting ΔsolHmθ against (T – 298.15) K, a good straight line was obtained, with the slope of the line being the standard molar heat capacity of solution, ΔCp,mθ = 411 J·K–1·mol–1, for [C2mim][OAc], and the specific heat capacity of solution, ΔCpθ = 2.4 J·g–1·K–1, was also obtained.

Kinetic and equilibrium studies of σ-adduct formation and nucleophilic substitution in the reactions of 2-chloro-3,5-dinitropyridine and 2-ethoxy-3,5-dinitropyridine with p-substituted anilines in DMSO

Rate and equilibrium results for the reactions of 2-chloro-3,5-dinitropyridine and 2-ethoxy-3,5-dinitropyridine with a series of p-substituted anilines in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) were studied in DMSO. The reactions yielded 2-anilino-3,5-dinitropyridine derivatives, and no accumulation of intermediates could be detected spectrophotometrically. The rates were compatible with a two-step mechanism involving initial nucleophilic attack followed by either base-catalysed or uncatalysed conversion to the product. The base-catalysed pathway was likely to involve rate-limiting proton transfer from the zwitterionic intermediate to the base to yield the anionic σ-adduct. Plots of log K 1 k DABCO against pK a values gave good straight lines at 25 °C, with slopes of 0.42 for 2-chloro- and 0.45 for 2-ethoxy-3,5-dinitropyridine. The results were compared with those for the reactions of 2-phenoxy-3,5-dinitropyridine with substituted anilines.

The origin of trimethyldibenzothiophenes and their application as maturity indicators in sediments from the Liaohe Basin, East China

The distributions of trimethyldibenzothiophenes (TMDBTs), the relationship between TMDBTs and trimethylbiphenyls (TMBPs) and the application of TMDBTs as maturity indicators have been investigated in a set of lacustrine shales from the Eocene Shahejie Formation in the Liaohe Basin, East China. The 3,5,3′-, 3,5,4′- and 3,4,4′-TMBP isomers can react to yield (2,4,6-+2,4,8)-TMDBT, 2,4,7-TMDBT, and (3,4,7+2,3,7)-TMDBT by incorporating a sulfur atom into biphenyl, respectively. The absolute concentrations of (2,4,6+2,4,7+2,4,8)-TMDBT increase with those of (3,5,3′+3,5,4′)-TMBP. Similarly, the absolute concentrations of (3,4,7-+2,3,7)-TMDBT show a similar increase with those of 3,4,4′-TMBP. The good straight line relationships (R2=0.96) indicate the product–precursor links between TMDBTs and TMBPs in the sediments. On the basis of the possible differences in the thermodynamic stability among TMDBT isomers, a new maturity indicator 2,4,6-/(2,4,7+2,4,8)-TMDBT ratio is proposed in this study. This ratio has a good correlation with 4-/1-methyldibenzothiophen ratio (MDR) and Tmax (°C), respectively, indicating similar behavior with increasing maturity. Both of the 2,4,6-/(2,4,7+2,4,8)-TMDBT ratio and MDR exhibit similar maturation trends. They gradually decrease with increasing maturity at the low maturity stages, and then are followed by a regular increase with the increasing maturity. Therefore, this ratio is an effective maturity indicator for source rocks and an oils maturity assessment (Ro>≈0.55%), and it must be applied with caution as a maturity indicator for extracts of immature sediments.

The Effect of Applied Stress on Environment-Induced Cracking of Aluminum Alloy 5052-H3 in 0.5 M NaCl Solution

The environment-induced cracking (EIC) of aluminum alloy 5052-H3 was investigated as a function of applied stress and orientation (Longitudinal rolling direction—Transverse: LT and Transverse—Longitudinal rolling direction: TL) in 0.5 M sodium chloride solution (NaCl) using a constant load method. The applied stress dependence of the three parameters (time to failure;tf, steady-state elongation rate,Iss, and transition time at which a linear increase in elongation starts to deviate,tss) obtained from the corrosion elongation curve showed that these relationships were divided into three regions, the stress-dominated region, the EIC- dominated region, and the corrosion-dominated region. Aluminum alloy 5052-H3 with both orientations showed the same EIC behavior. The value oftss/tfin the EIC-dominated region was almost constant with0.57±0.02independent of applied stress and orientation. The fracture mode was transgranular for 5052-H3 with both orientations in the EIC-dominated region. The relationships between logIssand logtffor 5052-H3 in the EIC-dominated region became a good straight line with a slope of −2 independent of orientation.