H2O Mixtures Research Articles

Numerical simulation on high-temperature supercritical CO2/gaseous H2O mixture flowing over a single reactive spherical char particle

Based on PR-DNS (Particle Resolve-Direct Numerical Simulation) method, the gasification process of a single spherical char particle moving in high-temperature supercritical CO2/gaseous H2O atmosphere at 9 MPa is conducted, and related mechanism on the reaction-affected drag of the sphere, flow field and interphase thermal as well as mass transfer near sphere surface is presented. The reaction temperature and Re (Reynolds number) of the fluid flowing over the sphere are variable within the range of 1273.15–1673.15 K and 10–200, respectively. The mass decomposition source on the sphere surface (Stefan flow), reaction heat, heat radiation between fluid species and char, porous inert ash layer and variations on physical properties of fluid mixture near the sphere surface are taken into account, while the Pseudo-Steady-State approach is employed for handling the particle shrinking. The results indicate that the higher reaction temperature leads the smaller drag coefficient, while enhances the performance of heat transfer compared with that of non-reactive cases. Due to the relative strength between convective heat transfer and endothermic effect of heterogeneous reaction, variation laws of temperature on the sphere surface vs. Re differs from each other under different reaction temperatures. Higher temperature and lower Re leads the higher surface Damköhler numbers, which indicates that the heterogeneous reactions in gasification process have normal characteristic of reactions in the kinetically-controlled regime. Porous inert ash layer increases resistance to flow as well as diffusion of species, and the variations in relative concentration of fluid reactants can also result in varied influences on above variables.

High-Degree Oxidative Desulfurization of a Commercial Marine Fuel Using Deep Eutectic Solvents and Their Recycling Process

Escalating environmental concerns have dictated the need to develop innovative methods for efficiently desulfurizing marine fuels (heavy fuel oils). In this work, the oxidative desulfurization method using deep eutectic solvents (DESs) was applied to reduce the sulfur content in a commercially available heavy fuel oil (HFO) below 0.5 wt.%, as current regulations demand. Initially, the S-compounds in the fuel were oxidized using an oxidative mixture of H2O2 with carboxylic acid (either acetic or formic acid). Subsequently, the oxidized S-compounds were extracted from the fuel using a series of environmentally friendly deep eutectic solvents (DESs), the best of which was proven to be a mixture of choline chloride with ethylene glycol at a 1/2 molar ratio. The process was optimized by investigating the effect of several process parameters on the desulfurization efficiency, namely, the H2O2/S molar ratio, the H2O2/acid molar ratio, the acid type, the oxidation temperature and oxidation time, the solvent/fuel mass ratio, the extraction time, and the extraction temperature. A desulfurization efficiency of 75.7% was achieved under the optimized conditions, reducing the S content in the fuel to 0.33 wt.%. Furthermore, different methods to recycle the DESs were investigated, and consecutive desulfurization and solvent regeneration cycles were performed. The most efficient recycling method was determined to be the anti-solvent addition of excess water, which resulted in 89.5% DES purification by causing precipitation of the dissolved solids. After three cycles of desulfurization and regeneration using different recycling routes, it was found that the regeneration degree declines gradually; however, it is more than 79.3% in all cases.

Complex Ice Chemistry: A comparative study of electron irradiated planetary ice analogues containing methane

Various Solar System objects are covered in layers of ice that are dominated by H2O, CH4, and N2 and in which complex chemical processes take place. In this work, the influence of composition and irradiation duration on the volatile irradiation products of mixed CH4:N2, CH4:H2O, and CH4:H2O:N2 ices after electron irradiation are studied. The ices were irradiated for 2 or 4 h with 5 keV electrons, followed by a temperature programmed desorption, where the desorption of the volatile irradiation products was observed. The formation of C2Hx and C3Hx is observed in all ices and for both irradiation times. For the ices containing H2O, molecules as large as tentatively identified C4Hx and C5Hx are observed to co-desorb with water, whereas for CH4:N2 a continuous desorption signal is observed instead of a sharp desorption peak. A decrease in signal intensity from the 2 to the 4 h irradiation is observed for most m/z signals in CH4:H2O and CH4:H2O:N2 ices, whereas the opposite is recorded for CH4:N2, where in general larger signal for longer irradiation duration is seen. The addition of nitrogen to the CH4:H2O ice did not lead to clear identification of different molecules, but instead to a decrease of the observed signal for complex molecules, suggesting that the addition of nitrogen to the CH4:H2O mixture primarily leads to a more effective incorporation of material in an organic residue. The analysis of the residue will be subject of future work to complement the findings in this study.

In Situ and Ex Situ Studies of Ring-Like Assembly of Silica Nanoparticles in the Presence of Poly(propylene oxide)-Poly(ethylene oxide) Block Copolymers.

Block copolymer-mediated self-assembly of colloidal nanoparticles has attracted great attention for fabricating various nanoparticle arrays. We have previously shown that silica nanoparticles (SNPs) assemble into ring-like nanostructures in the presence of temperature-responsive block copolymers poly[(2-ethoxyethyl vinyl ether)-block-(2-methoxyethyl vinyl ether)] (PEOVE-PMOVE) in an aqueous phase. The ring-like nanostructures formed within an aggregate of PEOVE-PMOVE when the temperature was increased to 45 °C, at which the polymer is amphiphilic. Herein, we report that SNPs assemble into ring-like nanostructures even with a different temperature-responsive, amphiphilic block copolymer poly(propylene oxide)-block-poly(ethylene oxide) (PPO-PEO) at 45 °C. Field-emission scanning electron microscopy for SNP assemblies that were spin-coated on a substrate indicated that SNP first assembled into chain-like nanostructures and then bent into closed loops over several days. In contrast, in situ small-angle X-ray diffraction measurements revealed the formation of SNP nanorings within 75 s at 45 °C in the liquid phase. These results indicated that ring-like assembly of SNPs occurs quickly in the liquid phase, but the slow formation of Si-O-Si bonds between SNPs leads to their structure being destroyed by spin-coating. Intriguingly, SNPs with a diameter of 15 nm form a well-defined nanoring structure, with five SNPs located at the vertex points of a regular pentagon. Additionally, small-angle neutron scattering, where the contrast of the solvent (a mixture of H2O and D2O) matches that of SNPs, clarified that SNPs are contained within the spherical micelle formed from PPO-PEO. This work offers a facile and versatile approach to preparing ring-like arrays from inorganic colloidal nanoparticles, leading to applications including sensing, catalysis, and nanoelectronics.

Conversion of CO2 through solid oxide co-electrolysis cell with cobalt-free fuel electrode

As an efficient device to convert CO2/H2O into fuels through renewable energy, Solid Oxide Electrolysis Cell (SOEC) has gotten considerable attention. However, the compromised activity of the fuel electrodes has restrained the development of SOEC. To improve the overall performance of the SOEC in this work, Nb and Sr are doped in LaFeO3 to prepare La0.9Sr0.1Fe0.9Nb0.1O3-δ (LSFN) perovskite material used as the fuel electrode. The results show that LSFN exhibits excellent stability and high performance as a fuel electrode. Meanwhile, the current density can reach up to 1.516 A cm−2 and 1.394 A cm−2 @1.5 V at 850 ℃ with the composition of 40%H2O-60%H2 and 30%CO2-50%H2O-20%H2 respectively. Finally, the LSFN|GDC|YSZ|GDC|LSCF shows excellent stability, running stably for ∼ 60 h under the condition of a mixture of H2O and CO2 at 850 ℃. Overall LSFN is a highly efficient and stable fuel electrode for SOEC applications.

Bioapatite derived from animal bones as support for environmentally concerned catalysts: WGS with suppressed methanation activity

The potential of natural apatite derived from pork bones to be used as a support of Ni catalysts for the Water-Gas Shift (WGS) reaction was investigated. Samples of bone char were chemically treated with either K2CO3 or H2SO4 and subsequently heated in inert or oxidizing atmosphere at various temperatures. Catalysts were characterized by ICP-AES, N2 physisorption, XRD, FTIR, TG-DTG, H2-TPR, XPS, H2 chemisorption and NH3-TPD, and tested in the WGS reaction, using both ideal and realistic (mixture of H2O, CO2 and H2) feed streams. Nickel was partly exchanged with Ca2+ ions in the support. Regarding the effect of the atmosphere, an inert atmosphere had a negative effect due to the collapse of the porous structure. On the contrary, the combination of an oxidizing atmosphere and treatment with K2CO3 allowed a superior WGS performance under real reformer conditions, with a substantial decrease in the methane formation (six-fold decrease, compared to the non-activated reference catalyst). The catalytic activity could be related to the apatitic phase growing geometry, which can be tailored by the activation method.

Effect of fracture behavior variables on hydraulic fracturing optimization by adding graphene nanosheets to sand/water mixtures: A molecular dynamics approach

Hydraulic fracture is one of the promising techniques for the breakage of rock without blasting, thus the investigation of its internal mechanism is helpful to develop forecasting system for ground pressure. In this study, molecular dynamics (MD) method was used to describe the effect of graphene nanosheets (GNS) (with different edges) on the hydraulic fracturing process. More specifically, in the MD box, we simulated the effects of GNS on rock substrates, the mixtures of H2O and sand, and sands that deviate from the specified atomic substrates. Therefore, we calculated the parameters, such as temperature, total energy and mutual forces of atomic structures. In these simulations, mixture fluid is simulated by sand particles and water molecules with the Universal Force Field (UFF). Physically, adding GNS to mixture fluid caused a decrease in the number of trapped sand particles in the fracture of rock matrix. The sand particles removed from rock matrix fracture. This atomic phenomenon optimized the hydraulic fracturing process and reduced operating costs. Numerically, in our simulations, the atomic structures’ temperature and potential energy converged to 300 K, and −479 eV (respectively). Furthermore, trapped sand particles in MD simulations decreased to 14 particles using GNS. Our results show that the trapped sand particles reached their minimum rate (14 particles) by 2.5% atomic ratio of GNS inserting into the initial atomic mixture fluid. This atomic behavior results from the energy of the interactions between sand particles, and rock substrate. The interaction energy between the sand particles and the substrate reduced to a –32.38 eV by adding GNS to original H2O-sand mixture. This atomic evolution caused the volume of trapped sand particles reached to minimum value in the presence of GNS with optimum atomic ratio.

Waste Tyre Pyrolysis Oil: Production, Sulfur Removal and Fractionation for Value Added Products

Scrap tyres, one of the most common solid wastes, are increasing with the increase of vehicles number all over the world. Gradual depletion of fossil fuel requires a rapid shift towards alternative fuel sources including wastes. Globally, a lot of pyrolysis oil is generated from the management of waste tyres. The product Tyre pyrolysis Oil (TPO) has a parametric effect on the temperature, feed size, and reaction or pyrolysis time. This study explores the conditions for optimum pyrolytic oil yield (42% wt.) which was 500 ºC for 50 minutes, with a sample size of 4 cm3. The obtained TPO were fractionated at various temperature ranges using a distillation column. The fuel characteristics of TPO, e.g., viscosity, flash point, pour point, calorific value, density, carbon residue are almost similar to that of the conventional oil standards but it cannot directly be used in the combustion process due to its higher sulfur content. For the removal of the sulfur compound, a various concentration ratio (10, 15, 20, 25, 30 percentages) of a mixture of H2O2 and HCOOH (2:1) solution (maintaining a pH of 4) were mixed with TPO. A maximum of 64.52% sulfur was removed from the TPO by using 25% of H2O2 + HCOOH solution and the pyrolysis gas was passed through the Ca(OH)2 solution for wet scrubbing of SO2, CO2 and water vapor. The fractionated TPO (based on temperature range) provides valuable products e.g., bio-gasoline, biodiesel and other desirable chemicals. The production and eco-friendly use of TPO and its fractionated products can mitigate the disposal problem of waste tyre and help the eco-system to attain a sustainable environment.
 J. of Sci. and Tech. Res. 4(1): 59-70, 2022

Quasi-elastic neutron scattering reveals the relationship between the dynamical behavior of phospholipid headgroups and hydration water.

The dynamics of hydration water (HW) in 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE) was investigated by means of quasi-elastic neutron scattering (QENS) and compared with those observed in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). The headgroup dynamics of DMPE was investigated using a mixture of tail-deuterated DMPE and D2O, and the QENS profiles were interpreted as consisting of three modes. The fast mode comprised the rotation of hydrogen atoms in -NH3+ and -CH2- groups in the headgroup of DMPE, the medium-speed mode comprised fluctuations in the entire DMPE molecule, and the slow mode comprised fluctuations in the membrane. These interpretations were confirmed using molecular dynamics (MD) simulations. The HW dynamics analysis was performed on a tail-deuterated DMPE and H2O mixture. The QENS profiles were analyzed in terms of three modes: (1) a slow mode, identified as loosely bound HW in the DMPC membrane; (2) a medium-speed mode similar to free HW in the DMPC membrane; and (3) a fast mode, identified as rotational motion. The relaxation time for the fast mode was approximately six times shorter than that of rotational water in DMPC, consistent with the results of terahertz time-domain spectroscopy. The activation energy of medium-speed HW in DMPE differed from that of free HW in DMPC, suggesting the presence of different hydration states or hydrogen-bonded networks around the phosphocholine and phosphoethanolamine headgroups.

Investigation for improvement of discharging rate within a renewable energy storage system with adding nano-powders

Discharging process through a renewable energy unit in existence of nanoparticles as additives has been simulated numerically. The estimation of properties of working material (mixture of H2O and alumina) has been done via single phase technique. Model includes two equations dominated by conduction mode because the convective rate is negligible. FEM modeling has been verified based on utilized assumptions. With dispersing nanoparticles, the rate of heat release enhances and freezing time declines about 41.18 %. With increase in dp of alumina powders from 30 to 40, the period of process reduces around 19.96 %.

Effects of Mn and Cu on descaling of hot-rolled 304L stainless steel in HCl and H2O2 mixtures

Abstract Descaling of stainless-steel black coil is an important step to produce white coil with smooth glossy surface. The AISI 304L black and white coils from a company containing 1.08–1.71Mn and 0.22–0.40Cu (wt%) were used to study the effects of Mn and Cu on descaling rate by potentiodynamic polarization technique at 25 °C. The pickling solutions were 0.5 M HCl and 0.5 M HCl mixed with H2O2 of 0.5, 0.88 and 1.76 M. The polarization curves of black and white coil samples measured in HCl–H2O2 mixture showed no passive range. The descaling rate of black coil oxide scales, and the corrosion potential (E corr) increased with H2O2 concentration. Low-Mn sample, that is 1.08%Mn0.23%Cu sample, showed higher descaling rate than high-Mn samples. No effects of Cu content on the descaling rate were observed. For white coil samples, the descaling rates were almost constant, but pitting on surface was observed. Passive films were eliminated. The corrosion potentials of black and white coil samples increased when adding H2O2 in HCl solution indicating an increase in cathodic reaction due to increase in dissolved oxygen. The corrosion potentials of 1.08%Mn0.23%Cu black and white coil samples were lower than those of high-Mn samples corresponding to less Mn oxide.

Solvent Mediated Interactions on Alkene Epoxidations in Ti-MFI: Effects of Solvent Identity and Silanol Density

Selective alkene oxidation rates within zeolite pores reflect differences in contributions from thermodynamic nonidealities introduced by noncovalent interactions at solid–liquid interfaces and spatial constraints enforced by the zeolite topology. Epoxidation turnover rates for 1-hexene in Ti-MFI zeolite differ by 1000-fold across 10 combinations of solvents, including alcohols and acetonitrile, over Ti-MFI with distinct silanol defect densities. Solvent mediated noncovalent interactions persist across an extended binding environment that influences the stability of epoxidation transition states. Apparent activation enthalpies (ΔHApp⧧) and entropies (ΔSApp⧧) span 80 kJ mol–1 and 200 J mol–1 K–1, respectively, with the most positive values for both appearing in methanol. Hydrophilic (i.e., (SiOH)x defect rich) Ti-MFI-OH catalysts in methanol give the greatest turnover rates because entropic gains associated with the disruption of hydrogen-bonded networks of intrapore methanol and water dominate activation free energies. In situ infrared spectra show that the adsorption of 1,2-epoxyhexane to Ti sites disturbs the equilibrium solvent structure within pores in ways that reflect the density of the hydrogen bond donor and acceptors near active sites. This interpretation agrees with measured enthalpies for adsorption of 1,2-epoxyhexane to Ti active sites within solvent filled pores that correlate with ΔHApp⧧ across solvent and catalyst combinations. The displacement of solvent molecules and the associated rupture and formation of hydrogen bonds among solvents, pore walls, and nearby reactive molecules during catalysis and adsorption events incur substantial excess contributions that govern the reaction rates and barriers. These realizations explain the particular success of alkene epoxidations in mixtures of H2O2 and methanol over hydrophilic forms of Ti-MFI in industrial processes (e.g., the hydrogen peroxide–propylene oxide process). These findings demonstrate the gains achieved by appropriately pairing organic solvents with microporous catalysts to manipulate the intrinsic kinetics of reactions and the thermodynamics of adsorption at solid–liquid interfaces.

Molecular perspectives of interfacial properties of the hydrogen+water mixture in contact with silica or kerogen

Interfacial behaviours in multiphase systems containing H2 are crucial to underground H2 storage but are not well understood. Molecular dynamics simulations were carried out to investigate interfacial properties of the H2+H2O and H2+H2O+silica/kerogen systems over a broad range of temperatures (298 - 523 K) and pressures (1 - 160 MPa). The combination of the H2 model with the INTERFACE force field and TIP4P/2005 H2O model can accurately predict the experimental interfacial tensions (IFTs) of the H2+H2O mixture. The IFTs from simulations are also in accordance with predictions from density gradient theory combined with the PC-SAFT equation of state. In general, the IFT decreases with pressure and temperature. However, at relatively high temperatures and pressures, the IFTs increase with pressure. The opposite pressure influence on IFTs can be explained by the inversion of the sign of the relative adsorption of H2. The H2 enrichment in the interfacial regions was identified in density distributions. Meanwhile, the behaviours of contact angles (CAs) in the H2+H2O+silica system are noticeably different from those in the H2+H2O+kerogen system. The H2O CAs for the H2+H2O+silica and H2+H2O+kerogen systems increase with pressure and decrease with temperature. However, the influence of temperature and pressure on these CAs is less pronounced for the H2+H2O+silica system at low temperatures. The behaviours of CAs were understood based on the variations of IFTs in the H2+H2O system (fluid-fluid interaction) and adhesion tensions (fluid-solid interaction). Furthermore, the analysis of the atomic density distributions indicates that the presence of H2 in between the H2O and the silica/kerogen is almost negligible. Nevertheless, the adsorption of H2O on the silica outside the H2O is strong, while less H2O adsorption is seen on the kerogen.

Experimental Investigation Into Effects of Thermodynamic Hydrate Inhibitors on Natural Gas Hydrate Synthesis in 1D Reactor

Thermodynamic hydrate inhibitors (THIs) are often used in marine gas field operations to prevent the formation of natural gas hydrate (NGH), and it is important to study the effect of THIs on hydrate synthesis characteristics. Herein, the effects of water (H2O), sodium chloride (NaCl), and ethylene glycol (EG) on NGH synthesis characteristics under different initial pressure conditions are tested using the self‐developed 1D NGH production simulation test system. The effects of each THI on the maximum synthesis rate and maximum synthesis amount of NGH are investigated using two physical quantities, peak of temperature increment and maximum gas conversion rate. The results show that the 2.65 wt% salt solution has the minimum inhibition effect on the maximum synthesis rate of NGH, and the solution with a 3:1 mixture of H2O and EG has the maximal inhibition effect on the maximum synthesis rate of NGH. When only H2O and EG or H2O and NaCl are present in the reactor, the higher the concentration of EG or NaCl, the more significant is the inhibition effect on the maximum synthesis amount of NGH.

New gas radiation model based on the principle of weighted sum of gray gases. Application to CO2–H2O mixtures at high temperature

A new gas radiation model based on the principle of weighted-sum-of-gray-gases (WSGG) is proposed. It is shown that expressing the weighting factors as linear functions of the temperature is more suitable than the fourth-order polynomial dependence to the temperature that is commonly adopted in the WSGG model. Using an efficient inverse algorithm, it was estimated a set of twelve spatially nonconstant parameters of the new model based on four gray gases, namely the coefficients of the linear functions and the pressure absorption coefficients. The inverse algorithm is based on the adjoint state of the radiative transfer equation (RTE) using as data the total radiative heat source instead of the total gas emissivity data. The parameters are fitted using data generated with line-by-line (LBL) simulations based on HITEMP2010. In the present work, the proposed gas radiation model is applied to determine the parameters of H2O–CO2 mixtures at atmospheric pressure with partial pressure ratio equal to 2, within the range of temperature between 400 K and 1800 K and for thicknesses of the gas layer up to 3.0 m. By applying the inverse algorithm to a given case, the present gas radiation model has the level of accuracy of the LBL method. The application of the same parameters to other test cases does not lead to the same level of accuracy, since the parameters obtained are spatially dependent. However, averaging these parameters in the inverse algorithm results in a gas radiation model with spatially constant parameters. When applied to several (1-D and 3-D) test cases in the conditions for which the parameters were obtained, this led to a significant reduction in the normalized errors on the radiative heat source and, for many of these cases, on the radiative heat flux compared to that obtained with the standard WSGG model.

Use of perennial plants in the fight against gastrointestinal nematodes of sheep

BackgroundGastrointestinal nematodes (GINs) are a serious problem in ruminant pastures worldwide. They generate production losses, from the point of view of both the food chain and animal mortality. This study provides preliminary results concerning the use of pasture plants in the Campania region (of southern Italy) to control GINs in sheep.MethodsSixteen species of wild and cultivated perennial plants present in seminatural pastures were sampled. All species were extracted with the conventional maceration technique, using three different solvents (i.e., H2O, EtOH, and an EtOH:H2O (8:2) mixture) in order to extract different bioactive compounds. The total phenolic content (TPC; assessed via the Folin–Ciocȃlteu assay) of all extract samples was preliminarily characterized. Each sample was aliquoted across six different concentrations and an in vitro egg hatching test (EHT) was conducted to evaluate the ovicidal effect on sheep GINs.ResultsThe results indicated that Cichorium intybus L. and Foeniculum vulgare Mill. extracts greatly inhibited egg hatching within 48 hours of exposure, showing efficacy (≥ 62.6%) at the three higher concentrations when compared with the other plants.ConclusionThe use of extracts of wild and cultivated perennial plant species in pastures can be a valid alternative to the use of synthetic anthelmintic drugs, which can generate problems, such as anthelmintic resistance, in the long term. Looking forward, further in vitro studies that evaluate the in vitro effect of these extracts on ruminant cell cultures, and field application through in vivo studies, would likely confirm the results obtained from preliminary in vitro EHTs. All these studies should be aimed at evaluating the therapeutic potential and future applicability of specific plant cultures in pastures to achieve sustainable pest control.

Determination of the Levels of Selected Heavy Metals in Finger Millet (Eleusine coracana) Flour in West Gojjam Zone, Amhara Region

Background: Finger millet is a native and indigenous food crop in Ethiopia and has been cultivated in different parts of the country for centuries. However, its heavy metal contents in other parts of Ethiopia were not well studied, especially in the study area. The study was conducted in the Mankussa and Finoteselam district of the western Gojjam zone, Amhara region Ethiopia, to determine the heavy metal (Mn, Fe, Zn, Cu and Pb) levels of finger millet by using inductively coupled plasma optical emission spectroscopy. Methods: A wet digestion procedure was developed using a mixture of HCl, HNO3 and H2O2 to decompose a mixed powdered finger millet sample. Result: Mn, Fe, Cu, Zn and Pb mean levels were 3.751, 1.699, 0.072, 0.4485 and 0.024 mg/L, respectively, in Mankussa Black finger millet samples. In Mankussa mixed finger millet, the mean metal levels were 3.573 mg/L, 2.7585 mg/L, 0.0585 mg/L, 0.799 mg/L and 0.024 mg/L for Mn, Fe, Cu, Zn and Pb, respectively and the mean metal levels of Mankussa White Finger millet were found to be 2.326, 2.289, 0.045, 0.5985 and 0.014 mg/L of Mn, Fe, Cu, Zn and Pb respectively. While the mean metal level of Finoteselam black Finger millet samples was found to be 5.651 mg/L, 2.1955 mg/L, 0.0435 mg/L, 0.744 mg/L and 0.011 mg/L for Mn, Fe, Cu, Zn and Pb respectively, in the mixed finger millet it was 3.023 mg/L, 2.155 mg/L, 0.0525 mg/L,1.259 mg/L of Mn, Fe, Cu and Zn. In white finger millet, it was found to be 2.8695 mg/L, 1.412 mg/L, 0.0525 mg/L and 1.0735 mg/L of Mn, Fe, Cu and Zn. Pb was not detected by the instrument in Finoteselam mixed and white finger millet samples. The metal levels investigated in this study were comparable with international standards.

Combinational Vibration Modes in H2O/HDO/D2O Mixtures Detected Thanks to the Superior Sensitivity of Femtosecond Stimulated Raman Scattering.

Overtones and combinational modes frequently play essential roles in ultrafast vibrational energy relaxation in liquid water. However, these modes are very weak and often overlap with fundamental modes, particularly in isotopologues mixtures. We measured VV and HV Raman spectra of H2O and D2O mixtures with femtosecond stimulated Raman scattering (FSRS) and compared the results with calculated spectra. Specifically, we observed the mode at around 1850 cm-1 and assigned it to H-O-D bend + rocking libration. Second, we found that the H-O-D bend overtone band and the OD stretch + rocking libration combination band contribute to the band located between 2850 and 3050 cm-1. Furthermore, we assigned the broad band located between 4000 and 4200 cm-1 to be composed of combinational modes of high-frequency OH stretching modes with predominantly twisting and rocking librations. These results should help in a proper interpretation of Raman spectra of aqueous systems as well as in the identification of vibrational relaxation pathways in isotopically diluted water.

A comparative study of chlorine and bromine species addition on the explosion limits of hydrogen-oxygen mixtures

In this work, we investigate the effects of chlorine (Cl) and bromine (Br) containing species additions on the pressure-temperature explosion limits of hydrogen-oxygen (H2-O2) mixtures computationally. It is shown that, with the addition of HCl, Cl2, HBr and Br2, the explosion limit evolves from being a non-monotonic Z-shaped curve to monotonic or maintains its non-monotonic response depending on the different types of additives. Specifically, with the addition of HCl to the mixtures, the limit always maintains the non-monotonic structure, while with the addition of around 18% of Cl2, it loses its Z-shaped structure. Compared with HCl and Cl2, more sensitive responses were found for HBr and Br2. With the addition of around 1% of HBr and 0.7% of Br2 to the H2-O2 mixtures, the limit's non-monotonic feature disappears rapidly, and becomes a monotonic curve. Further detailed kinetics analysis explains that after the addition of the halogen species, the radical competitions are different at the low- (P = 1.0 × 102 Pa), intermediate- (P = 1.0 × 104 Pa) and high- (P = 1.0 × 106 Pa) pressures respectively, resulting in the change of the dominant reactions. These findings enhance the understanding of Cl and Br containing species sensitization for the explosion limits of the H2-O2 mixtures and help to understand the kinetic interaction between the H2-O2 system and halogen.

AIE properties of blue-light-emitting molecules based on triazine derivatives

Novel star-shaped molecules of triazine with different terminal oxyalkyl chains were synthesized and systematically investigated by aggregation induced emission (AIE) studies, photophysical properties, and electrochemical properties. These triazine derivatives have a broad absorbance range and good intramolecular charge transfer (ICT) character. They have a non-planar structure with a triazine as an acceptor and a benzene ring attached by a carbon-carbon single bond. The existence of terminal alkoxy chains increases steric hindrance, which is beneficial for limiting intramolecular motion and achieving AIE effect. They exhibit positive solvatochromism effect, high stokes shift and good fluorescence quantum yield. They exhibit AIE properties in N,N-dimethylformamide (DMF)/H2O mixtures. Among them, the AIE properties of 3-5OBCT is the most excellent and fluorescence intensity of 3-5OBCT in DMF/H2O mixtures with water fraction of 40% is 26.7 times that in pure DMF. Purely organic luminescent materials with AIE features exhibit high efficiency in non-doped OLEDs. Therefore, these materials have broad application prospects in the field of OLEDs.