Change In Mole Fraction Research Articles

Numerical analysis of the combustion characteristics of graphitic hydrogen-chlorine synthesis combustor with different intake strategies

This study investigates the effect of intake strategies on the combustion and flows characteristics of hydrogen-chlorine synthesis combustors via numerical methods. A crucial issue of hydrogen-chlorine synthesis combustor is to have a sufficiently low flame height and high conversion efficiency. In this study, the combustion performance of combustors equipped with the annular tube, plum nozzle, and porous-bullet nozzle has been thoroughly analyzed. The temperature distribution and gas flow are analyzed using the method of fluid-solid coupling, which indicates that the combustor with porous-bullet nozzle had the best gas distribution, the maximum HCl mole fraction at outlet is 97.24%, and the lowest flame height is 3.4 m, which is 27.15% lower than the combustor with the annular tube. Furthermore, the nozzle structure has a great influence on the fluid velocity in the recirculation zone of the combustor. Finally, the effect of hydrogen/chlorine equivalence ratio (ϕ) and inlet volume flow rate were analyzed, and it can be concluded that with the increase of inlet volume flow, the high-temperature area inside the combustor gradually increases. As the equivalent ratio increases, the combustor outlet's mole fraction changes with a normal distribution trend. It is the most appropriate when the chlorine gas flow rate is 1,100 m3/h and ϕ = 1.05. The research can be applied to the field of high-purity hydrogen chlorine production, providing researchers with some solutions.

Improvements of a low-cost CO2 commercial nondispersive near-infrared (NDIR) sensor for unmanned aerial vehicle (UAV) atmospheric mapping applications

Abstract. Unmanned aerial vehicles (UAVs) provide a cost-effective way to fill in gaps between surface in situ observations and remotely sensed data from space. In this study, a novel portable CO2 measuring system suitable for operations on board small-sized UAVs has been developed and validated. It is based on a low-cost commercial nondispersive near-infrared (NDIR) CO2 sensor (Senseair AB, Sweden), with a total weight of 1058 g, including batteries. The system performs in situ measurements autonomously, allowing for its integration into various platforms. Accuracy and linearity tests in the lab showed that the precision remains within ± 1 ppm (1σ) at 1 Hz. Corrections due to temperature and pressure changes were applied following environmental chamber experiments. The accuracy of the system in the field was validated against a reference instrument (Picarro, USA) on board a piloted aircraft and it was found to be ± 2 ppm (1σ) at 1 Hz and ± 1 ppm (1σ) at 1 min. Due to its fast response, the system has the capacity to measure CO2 mole fraction changes at 1 Hz, thus allowing the monitoring of CO2 emission plumes and of the characteristics of their spatial and temporal distribution. Details of the measurement system and field implementations are described to support future UAV platform applications for atmospheric trace gas measurements.

Tuning the responsible parameters for gain characteristics of the novel type-II D-QW (InGaAs) heterostructure

The study made in this paper is directed towards the tuning of the parameters responsible for the shift in optical properties of a novel type-II D-QW (double quantum well) heterostructure having the QW of InGaAs and barrier of GaAsSb. This shift in optical properties has been observed via change in composition (change in mole fraction) of the constituent layers that form the heterostructure. The tunability of such parameters has been studied via computing the envelope functions, localized charge carriers, associated quantized energies and the matrix elements (i.e., optical and momentum matrix elements) which give information about the strength of the optical transitions responsible for optical gain of the quantum well heterostructure. For these computations, a multiband k. p model has been employed. Finally, the computed outcomes clarify that the proposed heterostructure is efficient to emit the radiations of 1.55 μm emission wavelength with high optical gain (6000/cm) and can be utilized in the O, E, and S bands of telecom window in optical communication.

Atmospheric oil and natural gas hydrocarbon trends in the Northern Colorado Front Range are notably smaller than inventory emissions reductions

From 2008 to mid-2016, there was more than a 7-fold increase in oil production and nearly a tripling of natural gas production in the Colorado Denver–Julesburg Basin (DJB). This study utilized air samples collected at the Boulder Atmospheric Observatory (BAO) tower in southwestern Weld County in the DJB to investigate atmospheric mole fraction trends of methane and volatile organic compounds (VOCs). Elevated methane and propane mole fractions and low values (<1) in the ratio of i-pentane to n-pentane at BAO were found to be associated with flow patterns that transport air from the northeast (NE) to east (E) sector to the site, the direction where the primary locations of oil and natural gas (O&NG) extraction and processing activities are located. Median mole fractions of the O&NG tracer propane at BAO were 10 times higher than background values when winds came from the NE quadrant. This contrasts with lower mole fractions of O&NG-related constituents in air parcels arriving at BAO from the south, the direction of the major urban area of Denver. None of O&NG tracers, for example, methane and propane, show statistically significant trends in mole fraction (relative to the background) over the study period in air transported from the DJB. Also, longer term acetylene mole fraction changes were not seen in NE quadrant or south sector samples. A significant decline in the mole fraction ratio of i-pentane to n-pentane in the NE sector data provides evidence of an increasing influence of O&NG on the overall composition of VOCs measured at BAO, a change not seen in measurements from the south (urban) sector. These results suggest that O&NG emissions and resulting atmospheric mole fractions have remained relatively constant over 2008–2016. The behavior in the observations is in contrast to the most recent VOC emissions inventory. While the inventory projects O&NG total VOC emission reductions between 2011 and 2020, of –6.5% per year despite the large production increases, the best estimate of the propane emission rate of change for the DJB-filtered data during 2008–2016 is much smaller, that is, –1.5% per year.

Effects of N2 dilution on laminar burning velocity, combustion characteristics and NOx emissions of rich CH4–air premixed flames

Effects of N2 dilution on laminar burning velocity (LBV), adiabatic flame temperature (AFT), intermediate radicals (CH3, H) and NOx emissions (NO, N2O) of methane were investigated using Bunsen burner under the condition of fuel-rich combustion (equivalence ratio 1.0 to 1.4). The Aramco mechanism was selected to analyze the effect of N2 blending on the adiabatic flame temperature and the intermediate radicals of CH4 premixed flame under the equivalence ratios (Φ = 0.8, 1.0, 1.2). The effect of different N2 doping ratios on the NOx emissions (NO, N2O) of methane was analyzed by using GRI 3.0 mechanism. The experimental and numerical results showed that as the equivalence ratio increased (from 1.0 to 1.4), the laminar burning velocity first increased and then decreased, reaching a maximum when the equivalence ratio was about 1.05. The mole fraction changes of intermediate radicals and NOx emissions also showed a trend of increasing first and then decreasing with the increasing of equivalence ratios. Under the same equivalence ratio, the mole fraction of intermediate radicals and NOx decreased as the N2 doping ratio increased. The sensitivity analysis showed that the major elementary reactions that inhibits the generation of intermediate radicals and NOx emissions were different under different equivalence ratios and N2 doping ratios. In addition, the sensitivity coefficients of the elementary reactions that mainly promotes or inhibits the generation of free radicals and NOx decreased with the increasing of the N2 addition.

Reciprocity between ion-dipole and hydrogen bond interactions in the binary mixtures of N,N-Dimethylformamide with ionic liquids

In this work, classical molecular dynamics (MD) simulations were carried out to investigate the structure and dynamics of binary mixtures of N, N-dimethylformamide (DMF) and ionic liquids (ILs), diethylammonium acetate (DEAA) and triethylammonium acetate (TEAA), with the change in mole fraction of ILs. The hydrogen bonding, dipole-dipole, and ion-dipole interactions were exclusively studied to explore the structural as well as dynamical evolution produced by the number of ionic entities in the mixtures. We have calculated the structural properties such as radial distribution functions (RDFs), spatial distribution functions (SDFs), and coordination numbers. These calculations were followed by studies involving dynamic properties like diffusion coefficients, hydrogen bond relaxation, and residence times. RDFs indicate the long-range correlations between ions in pure ILs. Structural properties also reveal an increase in ion-dipole interactions between DMF and ILs at high mole fractions of IL. These binary mixtures show high ion mobility at lower concentrations of ILs. Overall, the acetate anions show slightly higher diffusion than ammonium cations in pure ILs, and these two ions exhibit enhanced dynamics in the mixtures rich in DMF.

Modeling polymer electrolyte fuel cells: A high precision analysis

In this paper, a computational model is used to study the distributions of several key parameters and the performance of a fuel cell with an active area of 200 cm2. The results reveal that the model is capable of predicting the overall behavior in good agreement with experimental data and with superior resolution. Polarization curves are compared and cell voltage prediction deviations are within 43mV of experimental values. The predicted current density distribution is very close to both the experimentally measured results and a volume-average approach based on rate equations. Local variations of current density, oxygen, and water mole fraction change significantly from under-rib regions to under-channel regions. The serpentine type flow path leads to greater pressure gradients, but is beneficial to gas bypassing through the gas diffusion layers. This type of flow path helps to redistribute the species and current density distributions. Never before has it been possible to construct computational models capable of predicting fine-scale details in local current density; details which were not captured neither by previous models nor by present-day experiments.

Influence of thickness variation of gamma-irradiated DSSC photoanodic TiO2 film on structural, morphological and optical properties

Properties of photoanodic nanocrystalline oxide film may vary with thickness and gamma irradiation. In this work, photoanodic nanocrystalline TiO2 films of 5, 10, 15, 20, and 25 μm thickness were fabricated on glass substrate as well as irradiated with 10 kGy gamma irradiation dose. Effect of film thickness on morphological, compositional, structural and optical properties of the irradiate film were investigated using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffractometer (XRD) and UV–vis spectrophotometer. The XRD result showed significant change in mole fraction, phase content, crystal size, strain, specific surface area, morphology index, crystallites per unit surface area, and dislocation density of both anatase and rutile phase due to variation of irradiated film thickness. UV–vis-NIR spectroscopy results revealed that the optical bandgap increased with the increase of film thickness and found 2.80, 2.85, 3.15, 3.20, and 3.40 eV for 5, 10, 15, 20, and 25 μm film. These studies will be beneficial to more deeply understand the effect of both gamma radiation and variation in film thickness on several properties of photoanodic layer.

Photophysical study of an alkaloid harmaline in 1,4-dioxane-water mixtures

In this article we have studied the photophysics of an alkaloid harmaline in 1,4-dioxane-water mixtures. It was known that the microstructure of this binary mixture changes upon varying the mole fraction of 1,4-dioxane in mixture. We have observed that the photophysics of harmaline in 1,4-dioxane-water mixtures is modulated with change in mole fraction of 1,4-dioxane in the binary mixture. We have observed some interesting changes in the photophysical parameters of harmaline in 1,4-dioxane-water mixtures as a function of the mole fraction of 1,4-dioxane.

Estimation of equilibrium combustion products of diesel-biodiesel fuel blends using the developed solving process for CnHm and CαHβOg fuel blends

This study investigates the combustion products of diesel-biodiesel fuel blends by considering its chemical equilibrium state. In order to determine the equilibrium combustion products involving 10 species, a solving scheme which can be used for different fuel blends consisting of CnHm and C HO generic structures was developed. The constituted solving scheme was then applied for four different mixtures which were diesel, 20 and 50 % biodiesel additions (by volume), and 100% biodiesel. The change in mole fraction of the fuels and their blends was determined as a function of temperature, pressure and equivalence ratio. Besides, mass-based combustion product rates of CO2, CO and NO for a unity of fuel mass were also investigated for different temperatures and equivalence ratios. The results show that the addition of biodiesel to diesel fuel does not have any significant effect on the change in the mole fraction of the combustion products. However, the addition of biodiesel reduces slightly the formation of CO and NO, while CO2 shows a slightly increasing trend. In terms of mass-based combustion product rates, the biodiesel addition reduces the amount of CO2, CO and NO products because it increases the molecular weight of the fuel blends.

Interaction of 1-Butyl-3-methylimidazolium Trifluoromethanesulfonate with Ethyl Acetate/1-Butanol: Thermophysical Properties

Densities, speeds of sound and viscosities of pure and the binary mixtures of [BMIM][CF3SO3] + ethyl acetate or 1-butanol have been measured over the entire range of mole fractions at T = (298.15–323.15) K and at 0.1 MPa pressure using an Anton Paar density and sound velocity meter DSA 5000M and a Lovis microviscometer 2000M. The excess molar volumes (VE), viscosity deviations (Δη) and the isentropic compressibility deviations (ΔκS) have been calculated using the experimental data. The variations in VE, Δη and ΔκS with changes in mole fraction and temperature have been interpreted in terms of ion–dipole interactions and structural effects on mixing of IL and solvents. The Redlich–Kister equation has been fitted to the VE, Δη and ΔκS values using a multi-parametric nonlinear regression method. The PFP theory has been applied to correlate the excess molar volumes. The experimental and PFP correlated values of VE are found to be quite close to each other.

Rietveld Relaxation Analysis on LixNi0.5Mn1.5O4 (x = 0.1, 0.2) 5V Cathode Material

Introduction We have investigated the structural variation of γ-Fe2O3 after the termination of lithium insertion, and revealed the relaxation process from the discharging state to thermodynamically stable state [1-3]. We named this technique as “Relaxation analysis” and conducted this technique to various types of cathode or anode materials, such as LiMn2O4[4], LiFePO4[5], LiCoO2[6], or graphite [7] to clarify the insertion/extraction process as well as relaxation mechanism. In the present study, relaxation analysis has been made on the LixNi0.5Mn1.5O4 (x = 0.1, 0.2) after Li-extraction. LiNi0.5Mn1.5O4 with spinel-type structure is a promising cathode material because it operates at a higher voltage of ~4.7V [8] in comparison with the spinel cathode LiMn2O4. In the lithium extraction process, it has been reported that LixNi0.5Mn1.5O4 exhibits two existing phases (Li-rich and Li-lean phases) below x = 0.5 [9]. We investigated the structural relaxation of LixNi0.5Mn1.5O4 (x = 0.1, 0.2) by means of X-ray diffraction and the Rietveld analysis focusing on the change in molar ratio and structure parameter of two phases. Experiment Working electrode was prepared by LiNi0.5Mn1.5O4 powder (TOSHIMA Manufacturing Co.,Ltd) with Acetylene Black (AB) as a supplemental conductor and PVdF powder as an adhesive agent with ratio of 80 : 10 : 10 (weight ratio). Lithium foil was employed as the counter electrode and 1 mol·dm-3 LiPF6 in EC/EMC (3:7 v/v%, Kishida chemical Corp.,Ltd) was used as the electrolyte. Lithium was electrochemically extracted from LiNi0.5Mn1.5O4 using two electrode cell (Hohsen Corp.) at a constant current of 0.3C rate to obtain the sample of LixNi0.5Mn1.5O4 (x = 0.1,0.2). After the termination of Li extraction, we immediately removed the working electrode from the cell in a glove box to avoid the local cell reaction between the electrode material and the current collector. XRD data were collected from 10° to 120° in 2θ by using CuKα radiation (UltimaIV, Rigaku corp., Japan) at various relaxation time up to 70 hours. XRD data were analyzed by the Rietveld method using RIEVEC program [10]. Lattice constants and scale factors were obtained. Results and discussion Fig.1(a) and (b) show the X-ray diffraction patterns of x = 0.1 and x = 0.2 for LixNi0.5Mn1.5O4 measured after the termination of lithium extraction for 3h to 68h. Diffraction pattern gradually evolves with increasing relaxation time, i.e. the intensity of 400 peak of Li-rich phase develops while that of Li-lean phase does not change largely during relaxation. Each XRD profile can be well fitted with the Rietveld calculation. Fig.2 shows mole fraction changes of Li-rich phase. The mole fraction of Li-rich phase increases while that of Li-lean phase decreases with the relaxation time after lithium extraction. Fig.3 shows the variation of distance between oxygen and lithium for both phases. The O-Li distance of Li-lean phase is larger than that of Li-rich phase for both compositions. With the relaxation time up to 300-600 hours, Li-lean phase shrinks the O-Li distance, while Li-rich phase stretches it. It is found that, during the lithium extraction process, Li-lean phase is formed with excess amount of lithium ions, and it separates the Li-lean and Li-rich phases during the relaxation process. At the lithium extraction process, Li-lean phase with larger number of vacancy is favorable for lithium diffusion, while the ratio of Li-rich/Li-lean get into the equilibrium at the relaxation process. The decrease of the amount of lithium ion in Li-lean phase appears as the changes in the distance of oxygen and lithium. This phenomenon appears more clearly than when lithium extracted at a current of 0.1C rate.

Gas adsorption and desorption effects on cylinders and their importance for long-term gas records

Abstract. It is well known that gases adsorb on many surfaces, in particular metal surfaces. There are two main forms responsible for these effects (i) physisorption and (ii) chemisorption. Physisorption is associated with lower binding energies in the order of 1–10 kJ mol−1, compared to chemisorption which ranges from 100 to 1000 kJ mol−1. Furthermore, chemisorption only forms monolayers, contrasting physisorption that can form multilayer adsorption. The reverse process is called desorption and follows similar mathematical laws; however, it can be influenced by hysteresis effects. In the present experiment, we investigated the adsorption/desorption phenomena on three steel and three aluminium cylinders containing compressed air in our laboratory and under controlled conditions in a climate chamber, respectively. Our observations from completely decanting one steel and two aluminium cylinders are in agreement with the pressure dependence of physisorption for CO2, CH4, and H2O. The CO2 results for both cylinder types are in excellent agreement with the pressure dependence of a monolayer adsorption model. However, mole fraction changes due to adsorption on aluminium (< 0.05 and 0 ppm for CO2 and H2O) were significantly lower than on steel (< 0.41 ppm and about < 2.5 ppm, respectively). The CO2 amount adsorbed (5.8 × 1019 CO2 molecules) corresponds to about the fivefold monolayer adsorption, indicating that the effective surface exposed for adsorption is significantly larger than the geometric surface area. Adsorption/desorption effects were minimal for CH4 and for CO but require further attention since they were only studied on one aluminium cylinder with a very low mole fraction. In the climate chamber, the cylinders were exposed to temperatures between −10 and +50 °C to determine the corresponding temperature coefficients of adsorption. Again, we found distinctly different values for CO2, ranging from 0.0014 to 0.0184 ppm °C−1 for steel cylinders and −0.0002 to −0.0003 ppm °C−1 for aluminium cylinders. The reversed temperature dependence for aluminium cylinders points to significantly lower desorption energies than for steel cylinders and due to the small values, they might at least partly be influenced by temperature, permeation from/to sealing materials, and gas-consumption-induced pressure changes. Temperature coefficients for CH4, CO, and H2O adsorption were, within their error bands, insignificant. These results do indicate the need for careful selection and usage of gas cylinders for high-precision calibration purposes such as requested in trace gas applications.

Relaxation Structure Analysis of LixNiO2 (x=0.09) after Li-Extraction

Introduction We have investigated the structural variation of γ-Fe2O3 after the termination of lithium insertion, and revealed the transition of electrode material from kinetic state to equilibrium state clear [1,2]. We named this technique as “Relaxation analysis” and conducted this technique to various types of cathode or anode materials, such as LiMn2O4[3], LiFePO4[4], LiCoO2[5], or graphite [6] to clarify the insertion/extraction process as well as relaxation mechanism . LiNiO2 is one of the major cathode materials with low cost and low toxic nature in comparison with the widely used LiCoO2. LiNiO2 shows the rock-salt type structure with the space group, . When lithium is electrochemically extracted from the sample, two phases with similar structures (Li-rich and Li-lean phases) coexist below x = 0.32 of LixNiO2 [7,8]. In the present study, relaxation analysis has been performed on LixNiO2 (x = 0.09) after Li-extraction. We have investigated the structural relaxation of LixNiO2 (x = 0.09) by means of X-ray diffraction and the Rietveld analysis focusing on both the change of molar ratio and structure parameter in each phase. Experiment Working electrode was prepared by mixing LiNiO2 powder (Sumitomo Metal Mining Co., Ltd.) with Acetylene Black (AB) as a supplemental conductor and PVdF powder as an adhesive agent with the weight ratio of 80:10:10. Lithium foil was employed as the counter electrode and 1 mol∙dm-3 LiPF6 in EC/DMC (2:1 v/v%, Kishida chemical Co., Ltd) was used as the electrolyte. Lithium was electrochemically extracted from LiNiO2 using two electrode cell (Hohsen Co.) at a constant current of 0.01C rate to obtain the sample of Li0.09NiO2. After the termination of Li extraction, we immediately removed the working electrode from the cell in a glove box to avoid the local cell reaction between the electrode material and the current collector. XRD data were collected from 15 ° to 75° in 2θ for CuKα radiaton (RINT-TTR, Rigaku Co., Japan) at various relaxation time and were served for Rietveld structure analysis using RIEVEC program [9]. Results and discussion Fig.1 shows X-ray diffraction patterns of two phases of Li0.09NiO2 at various relaxation time after the termination of lithium extraction. Diffraction pattern gradually evolves with increasing relaxation time, i.e. the intensity of 003rich peak decreases and 003lean shifts toward the higher angle as observed in the inset. Each XRD profile can be well fitted with the Rietveld calculation. Fig.2 shows mole fraction changes of Li-lean phase. The mole fraction of Li-lean phase decreases while that of Li-rich phase increases with the relaxation time after lithium extraction. Fig.3 shows the variation of lattice constant (c-axis) for both phases. The Li-rich phase retains the c-length almost constant during the relaxation time, while Li-lean phase shrinks the c-axis. It is found that, during the lithium extraction process, Li-lean phase is formed with excess amount of lithium ions, and it separates the Li-lean phase without excess lithium ion and Li-rich phase during the relaxation process. At the lithium extraction process, Li-lean phase with larger number of vacancy is favorable for lithium diffusion, while the ratio of Li-rich/Li-lean get into the equilibrium with relaxation time.

Relaxation Rietveld Stage Analysis of Li Inserted Graphite after Charge/Discharge Cycles

Introduction Relaxation analysis makes transition of electrode material from kinetic state to equilibrium state clear. We have applied the Relaxation analysis to various kind of cathode and anode materials, such as γ-Fe2O3[1,2], LiMn2O4[3], LiFePO4[4], LiCoO2[5], LiMnPO4[6] and so on. In the previous work, we conducted relaxation analysis to graphite, the widespread anode material for lithium ion rechargeable batteries[7]. We analyzed the variation of stage structure of lithium-graphite intercalation compounds (Li-GICs) based on the one-dimensional Rietveld method[8]. In the present study, relaxation analysis was performed on the Li inserted graphite after a charge/discharge cycle and the results were compared for the case of first Li-insertion. Experiment Working electrode was prepared by mixing natural graphite powder (LB-CG, Nippon Kokuen) and PVdF with a ratio of 93 : 7 (weight ratio). Lithium foil was employed as the counter electrode and EC/DMC (2:1 volume ratio) with 1 mol∙dm-3 LiPF6was used as the electrolyte. Lithium ion was inserted into graphite electrochemically using two electrode cell. After the insertion, we extracted lithium ion from the sample, then we inserted lithium ion again into the sample. Current rate and charge/discharge periods were all selected to be 0.1C and 10h, respectively. Then two types of Li-GICs were prepared; the samples of lithium insertion at the first time (named 1st) and the second time (named 2nd). After the termination of each sample preparation, we immediately removed the working electrode from the cell in a glove box to avoid the local cell reaction between the electrode material and the current collector. XRD patterns from 11° to 53° in 2θ were measured by using CuKα radiaton (UltimaIV, Rigaku, Japan) for various relaxation time. We analyzed XRD patterns by the one-dimensional Rietveld method [6] using RIEVEC program coded by T. Yao[1-8]. Interlayer distances and scale factors of stage1 and stage2 were obtained. Results and discussion XRD profile of the sample for each relaxation time after Li insertion was well fitted by the Rietveld calculation. Fig.1 shows the obtained mole fraction changes of stage 1 for samples of 1st and 2nd, indicating that mole fractions of stage1 decrease and those of stage 2 increase with the relaxation time for both samples. It is considered that defective stage 1 was formed at the lithium insertion process, and it separated into stage 1 without defect and stage 2 during the relaxation. The change in mole fraction became slower for the 2nd. Fig.2 shows lattice parameters of c-axis for the stages 1 and 2. The lattice parameters of stage 1 were almost constant and those of stage 2 decreased during the relaxation for both samples. Although the structure of stage2 is generally presented as the stack of Li-inserted graphene layer and Li-not-inserted graphene layer, the stack of graphene layers with two different Li concentration at the interlayer also makes stage2 structure from the point of symmetry. It is considered that, at Li insertion process, Li-rich interlayer (D w) and Li-lean interlayer (D n) stacked to construct stage 2, and that structure of stage2 changed into the stack of Li-inserted (D w) and Li-not-inserted (D n) graphene layers during relaxation. Fig.3 shows two kinds of interlayer distance of stage 2, D w and D n, for both samples, where D w increased and D n decreased with the relaxation time. The changing manner of D w and D nwere similar for 1st and 2nd samples. It is considered that the process of structure change was similar for 1st and 2nd during the relaxation process, however, that the driving force from kinetic state to equilibrium state was weaker for 2nd sample than that of 1st sample by the loose of graphen layer stacking due to lithium ion insertion and extraction.

Establishment of a biosynthesis pathway for (R)-3-hydroxyalkanoates in recombinant Escherichia coli

A biosynthetic pathway for the production of (R)-3-hydroxyalkanoates (R3HAs) through in vivo depolymerization of poly(3-hydroxyalkanoates) [P(3HAs)] was constructed in recombinant Escherichia coli fadA mutant WA101 by introducing the Pseudomonas sp. 61–3 PHA synthase gene (phaC2) and the P. aeruginosa intracellular PHA depolymerase gene (phaZ). When recombinant E. coli WA101 strain expressing the phaC2 gene and the phaZ gene was cultured in Luria-Bertani (LB) medium containing 2 g/L of sodium decanoate, R3HAs could be produced to the concentration of 0.49 g/L. The mole fraction of R3HAs was 7.5mol% of 3-hydroxybutyrate (3HB), 31.6mol% of 3-hydroxyhexanoate (3HHx), 30 mol% of 3-hydroxyoctanoate (3HO), 29.4mol% of 3-hydroxydecanoate (3HD), and 1.5mol% of 3-hydroxydodecanoate (3HDD). When the E. coli 3-ketoacyl-ACP reductase gene (fabG) was overexpressed to provide more (R)-3-hydroxyacyl-CoA (R3HA-CoA), the concentration of R3HAs was increased up to 1.05 g/L. Also, expression of the fabG gene resulted in the mole fraction change of produced R3HAs, in which 3HD fraction was enriched from 29.4mol% to 57.9mol% with the decrease of 3HHx fraction from 31.6mol% to 9.6mol%. Interestingly, the only expression of the fabG gene in E. coli WA101 could produce R3HAs to 0.55 g/L, which suggests that E. coli might have unidentified CoA hydrolases that have substrate specificities toward R3HA-CoA. This study shows the enantiomerically pure RHAs can be efficiently produced by metabolically engineered E. coli with high yield.

Numerical modelling of multicomponent LNAPL dissolution kinetics at residual saturation in a saturated subsurface system

Characterization of aquifers contaminated by petroleum hydrocarbons is limited by the use of dissolution mass transfer correlations developed for single compounds without considering the effects of the mass transfer limitations in presence of other components. A one-dimensional implicit numerical model is developed for the coupled mass transfer and transport processes and the results are analysed using existing mass transfer correlations for better understanding of the single and multicomponent dissolution processes. The mass transfer coefficient in the multicomponent system is found to be more nonlinear and extending with changing slope, unlike the exponential reduction for single compound system. During the initial phase, the dissolution rate of a soluble compound is very high due to the high concentration gradient, and as dissolution progresses, its effective solubility decreases with change in mole fraction. At higher pore volumes, the mole fractions of lower solubility fractions increase which can result in higher effective solubility. The kinetics of interphase mass transfer by dissolution and sorption is favoured by coupled biodegradation. However, mass transfer limitation for more soluble compounds under the conditions of low residual saturation and low mole fraction is observed to be due to low dissolution rate coefficient rather than decreasing concentration gradient.

Relaxation Rietveld Stage Analysis of Li Inserted Graphite

Introduction Recently, we have conducted the relaxation analysis for various electrode materials such as γ-Fe2O3[1-2], LiMn2O4[3], LiFePO4[4], LiCoO2[5] after termination of electrochemical Li insertion/extracttion. Relaxation analysis makes transition of electrode material from kinetic state to equilibrium state clear.Graphite is widely used as a negative electrode material for lithium ion rechargeable batteries. When lithium ion is inserted into graphite, various lithium-graphite intecalation compounds (Li-GICs) are formed .Previously Yao et al.[6] synthesized Li-GICs and analyzed the layered structures crystallographically by the one-dimensional Rietveld method.In this study, we changed current when inserting lithium into graphite electrochemically and analyzed stage structures at the relaxation time by using the one-dimensional Rietveld method. We investigated the effect of the insertion current on the relaxation process. Experiment We prepared the working electrode by mixing natural graphite powder (LB-CG, Nippon Kokuen) and PVdF with a ratio of 93 : 7 (weight ratio). Lithium foil was used as the counter electrode. We inserted lithium electrochemically using two electrode cell. EC/DMC (2:1 volume ratio) with 1 mol∙dm-3 LiPF6 was used as the electrolyte. We prepared three samples with different current rate and discharging hour(G1:0.01C-100h, G2:0.02C-50h, G3:0.04C-25h). After the termination of Li insertion, we immediately removed the working electrode from the cell in a glove box to avoid the local cell action between the electrode material and the current collector. XRD patterns from 11 ° to 53° in 2θ were measured by using CuKα radiaton (UltimaIV, Rigaku corp., Japan) for various relaxation time. We analyzed XRD patterns by the one-dimensional Rietveld method [6] using RIEVEC program[1-6]. Interlayer distances and scale factors were obtained. Results and discussion XRD profiles of the samples for each relaxation time after Li insertion were well fitted by the Rietveld calculation. Fig.1 shows mole fraction changes of stage1 for samples( G1, G2, G3). The mole fraction of stage1 decreased and that of stage2 increased with the relaxation time for all samples. It is considered that defective stage1 was formed at the lithium insertion process, and at the relaxation time, it separated to stage1 without defect and stage2. The mole fraction change with relaxation time became the smaller for the lower current rate. Fig.2-4 shows lattice parameter of c-axis(Fig.2) in stage2 and two kinds of interlayer distance of stage2(Fig3-4) in three samples. The wider one (Dw) increased, and the narrower one (Dn) and lattice parameter decreased with the relaxation time. Generally, the structure of stage2 is presented as the stack of Li-inserted graphene layer and Li-not-inserted graphene layer. However, from the point of symmetry, stack of graphene layers with two different Li concentration at the interlayer makes stage2 structure. In this study, it is considered that, at Li insertion process, Li-rich interlayer (Dw) and Li-lean interlayer (Dn) stacked to construct stage 2, and that, at the relaxation time, structure of stage2 changed to stack of Li–fully-inserted graphene layer (Dw) and Li-not-inserted graphene layer (Dn). The relaxation of the lattice constant, Dw, and Dn were different with the insertion current. It is considered that the change of insertion current effect on the manner of Li insertion.

Relaxation Stage Analysis of Li Inserted Graphite By Means of One-Dimensional Rietveld Method

Introduction Recently, we have conducted the relaxation analysis for various electrode materials such as γ-Fe2O3[1-2], LiMn2O4[3], LiFePO4[4], LiCoO2[5] after termination of electrochemical Li insertion/extracttion. Relaxation analysis makes transition of electrode material from kinetic state to equilibrium state clear. Graphite is widely used as a negative electrode material for lithium ion rechargeable batteries. When lithium ion is inserted into graphite, various lithium-graphite intecalation compounds (Li-GICs) are formed. Previously Yao et al. synthesized Li-GICs and analyzed the layered structures crystallographically by the one-dimensional Rietveld method[6]. Recently, we inserted lithium into graphite electrochemically and investigated the relaxation process by means of the XRD [7]. In this study, by using the one-dimensional X-ray Rietveld analysis, we investigated the relaxation process of lithium inserted graphite. Experiment We prepared the working electrode by mixing natural graphite powder (LB-CG, Nippon Kokuen) and PVdF with a ratio of 93 : 7 (weight ratio). Lithium foil was used as the counter electrode. We inserted lithium electrochemically at a rate of 0.1C for 10 h using two electrode cell. EC/DMC (2:1 volume ratio) with 1 mol∙dm-3 LiPF6was used as the electrolyte. After the termination of Li insertion, we immediately removed the working electrode from the cell in a glove box to avoid the local cell action between the electrode material and the current collector. XRD patterns from 11 ° to 53° in 2θ were measured by using CuKα radiaton (UltimaIV, Rigaku corp., Japan) for various relaxation time. We analyzed XRD patterns by the one-dimensional Rietveld method [6] using RIEVEC program[1-6]. Interlayer distances and scale factors were obtained. Results and Discussion XRD profiles of the samples for each relaxation time after Li insertion were well fitted by the Rietveld calculation. Fig.1 shows relative mole fraction changes calculated from scale factor and unit cell volume[8] obtained. The mole fraction of stage1 decreased and that of stage2 increased with the relaxation time. It is considered that defective stage1 was formed at the lithium insertion process, and at the relaxation time, it separated to stage1 without defect and stage2. Fig.2 shows two kinds of interlayer distance of stage2. The wider one (Dw) increased and the narrower one (Dn) decreased with the relaxation time. Generally, the structure of stage2 is presented as the stack of Li-inserted graphene layer and Li-not-inserted graphene layer. However, from the point of symmetry, stack of graphene layers with two different Li concentration at the interlayer makes stage2 structure. In this study, it is considered that, at Li insertion process, Li-rich interlayer(Dw) and Li-lean interlayer(Dn) stacked to construct stage2, and that, at the relaxation time, structure of stage2 changed to stack of Li–fully-inserted graphene layer(Dw) and Li-not-inserted graphene layer(Dn).

Excess Molar Volumes and Viscosities of Binary Systems of Butylcyclohexane with n-Alkanes (C7 to C14) at T = 293.15 K to 313.15 K

Experimental values of densities and viscosities have been measured in the binary mixtures of butylcyclohexane (BCH) with n-heptane, n-octane, n-nonane, n-decane, n-dodecane, and n-tetradecane at temperatures T = (293.15 to 313.15) K and pressure p = 0.1 MPa over the entire mole fraction range. The excess molar volumes (VmE) and viscosity deviations (Δη) are calculated, and then the changes of VmE and Δη with the composition of BCH are fitted to the Redlich–Kister equation. The values of densities increase continuously with the increase of mole fraction of BCH while the values of viscosities show different trends. All the densities and viscosities decrease with the rise of temperature. The variations of VmE and Δη are discussed with the change of mole fraction of BCH and temperature. This work is useful to understand the molecular interaction in binary systems of liquid.