SciCombinator

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Concept: Henry's law

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Liquisolid technique is one of the methods used to improve the dissolution rate of the poorly water soluble drugs utilizing non volatile liquids.

Concepts: Temperature, Solubility, Phase, Solution, Carbonate, Solvation, Volatile, Henry's law

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Biological air filtration for reduction of emissions of volatile sulfur compounds (e.g., hydrogen sulfide, methanethiol and dimethyl sulfide) from livestock production facilities is challenged by poor partitioning of these compounds into the aqueous biofilm or filter trickling water. In this study, Henry’s law constants of reduced volatile sulfur compounds were measured for deionized water, biotrickling filter liquids (from the first and second stages of a two-stage biotrickling filter), and NaCl solutions by a dynamic method using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) at a temperature range of 3-45°C. NaCl solutions were used to estimate salting-out constants up to an ionic strength of 0.7M in order to evaluate the effect of ionic strength on partitioning between air and biofilter liquids. Thermodynamic parameters (enthalpy and entropy of phase exchange) were obtained from the measured partition coefficients as a function of temperature. The results show that the partition coefficients of organic sulfur compounds in the biotrickling filter liquids were generally very close to the corresponding partition coefficients in deionized water. Based on the estimated ionic strength of biofilter liquids, it is assessed that salting-out effects are of no importance for these compounds. For H(2)S, a higher enthalpy of air-liquid partitioning was observed for 2nd stage filter liquid, but not for 1st stage filter liquid. In general, the results show that co-solute effects for sulfur compounds can be neglected in numerical biofilter models and that the uptake of volatile sulfur compounds in biotrickling filter liquids cannot be increased by decreasing ionic strength.

Concepts: Photosynthesis, Water, Temperature, Thermodynamics, Sulfur, Hydrogen sulfide, Natural gas, Henry's law

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The insecticide methomyl, an oxime carbamate, was first introduced in 1968 for broad spectrum control of several insect classes, including Lepidoptera, Hemiptera, Homoptera, Diptera, and Coleoptera. Like other carbamates, it inhibits AChE activity, resulting in nerve and/or tissue failure and possibly death. Considered highly toxic to insects (larval and adult stages), methomyl is thought to be metabolically degraded via mixed-function oxidase(s). Methomyl has both a low vapor pressure and Henry’s law constant; hence, volatilization is not a major dissipation route from either water or moist or dry soils. Photolysis represents a minor dissipation pathway; however, under catalytic conditions, degradation via photolysis does occur. Methomyl possesses a moderate-to-high water solubility; thus hydrolysis, under alkaline conditions, represents a major degradation pathway. Methomyl has a low-to-moderate sorption capacity to soil. Although results may vary with soil type and organic matter content, methomyl is unlikely to persist in complex soils. Methomyl is more rapidly degraded by microbes, and bacterial species have been identified that are capable of using methomyl as a carbon and/or nitrogen source. The main degradation products of methomyl from both abiotic and biotic processes are methomyl oxime, acetonitrile, and CO₂. Methomyl is moderately to highly toxic to fishes and very highly toxic to aquatic invertebrates. Methomyl is highly toxic orally to birds and mammals. Methomyl is classed as being highly toxic to humans via oral exposures, moderately toxic via inhalation, and slightly toxic via dermal exposure. At relatively high doses, it can be fatal to humans. Although methomyl has been widely used to treat field crops and has high water solubility, it has only infrequently been detected as a contaminant of water bodies in the USA. It is classified as a restricted-use insecticide because of its toxicity to multiple nontarget species. To prevent nontarget species toxicity or the possibility of contamination, as with all pesticides, great care should be taken when applying methomyl-containing products for agricultural, residential, or other uses.

Concepts: Bacteria, Insect, Nitrogen, Vapor pressure, Insecticide, Partial pressure, Henry's law, Raoult's law

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A systematic thermodynamic analysis has been carried out for selecting cations and anions to enhance the absorption of volatile organic compounds (VOCs) at low concentration in gaseous streams by ionic liquids (ILs), using COSMO-RS methodology. The predictability of computational procedure was validated by comparing experimental and COSMO-RS calculated Henry’s law constant data over a sample of 125 gaseous solute-IL systems. For more than 2,400 solute-IL mixtures evaluated, including 9 solutes and 270 ILs, it was found that the lower the activity coefficient at infinite dilution () of solutes in the ILs, the more the exothermic excess enthalpy (HE) of the equimolar IL-solute mixtures. Then, the solubility of a representative sample of VOC solutes, with very different chemical nature, was screened in a wide number of ILs using COSMO-RS methodology by means of  and HE parameters, establishing criteria to select the IL structure that promotes favorable solute-solvent intermolecular interactions. As a result of this analysis, an attempt of classification of VOCs respect to their potential solubility in ILs was proposed, providing insights to rationally select the cationic and anionic species for a possible development of absorption treatments of VOC pollutants based on IL systems.

Concepts: Chemistry, Temperature, Solubility, Thermodynamics, Chemical compound, Volatile organic compound, Henry's law, Raoult's law

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About 85 years have passed since the shaking culture was devised. Since then, various monitoring devices have been developed to measure culture parameters. O2consumed and CO2produced by the respiration of cells in shaking cultures are of paramount importance due to their presence in both the culture broth and headspace of shake flask. Monitoring in situ conditions during shake-flask culture is useful for analysing the behaviour of O2and CO2, which interact according to Henry’s law, and is more convenient than conventional sampling that requires interruption of shaking. In situ monitoring devices for shake-flask cultures are classified as direct or the recently developed bypass type. It is important to understand the characteristics of each type along with their unintended effect on shake-flask cultures, in order to improve the existing devices and culture conditions. Technical developments in the bypass monitoring devices are strongly desired in the future. It is also necessary to understand the mechanism underlying conventional shake-flask culture. The existing shaking culture methodology can be expanded into next-generation shake-flask cultures constituting a novel culture environment through a judicious selection of monitoring devices depending on the intended purpose of shake-flask culture. Construction and sharing the databases compatible with the various types of the monitoring devices and measurement instruments adapted for shaking culture can provide a valuable resource for broadening the application of cells with shake-flask culture.

Concepts: Measurement, Cell culture, Culture, In situ, The Culture, Shake, The Various, Henry's law

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Keiji Morokuma, William Henry Emerson Professor Emeritus of Emory University and Research Leader at the Fukui Institute for Fundamental Chemistry, Kyoto University, passed away at the age of 83 on November 27, 2017. Morokuma made numerous contributions to theoretical methodologies for the determination of reaction mechanisms and the understanding of intermolecular interactions.

Concepts: Scientific method, Physics, Chemistry, Japan, Professor, Henry's law, Kyoto Prefecture

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Phthalates and phthalate alternatives are semi-volatile organic compounds (SVOCs) present in many PVC products as plasticizers to enhance product performance. Knowledge of the mass-transfer parameters, including the equilibrium concentration in the air in contact with the product surface (y0), will greatly improve the ability to estimate the emission rate of SVOCs from these products and to assess human exposure. The objective of this study was to measure y0 for different PVC products and to evaluate its relationship with the material-phase concentrations (C0). Also, C0 and y0 data from other sources were included, resulting in a substantially larger data set (Ntotal = 34, T = 25 °C) than found in previous studies. The results show that the material/gas equilibrium relationship does not follow Raoult’s Law and that therefore the assumption of an ideal solution is invalid. Instead, Henry’s Law applies and the Henry’s Law Constant for all target SVOCs consists of the respective pure liquid vapor pressure and an activity coefficient γ, which accounts for the non-ideal nature of the solution. For individual SVOCs, a simple partitioning relationship exists, but Henry’s Law is more generally applicable and will be of greater value in rapid exposure assessment procedures.

Concepts: Chemistry, Solubility, Physical chemistry, Chemical engineering, Partial pressure, Equilibrium chemistry, Henry's law, Raoult's law

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Kinetics and mechanism of limononic acid, (3-isopropenyl-6-oxoheptanoic acid, LA) oxidation by hydroxyl radicals (OH) and ozone (O3) were studied in the aqueous phase at 298±2 K. These reactions were investigated using liquid chromatography coupled to the electrospray ionization and quadrupole tandem mass spectrometry (LC-ESI/MS/MS). The rate coefficients determined for LA + OH reaction were: 1.3 ± 0.3 × 1010M-1s-1at pH=2 and 5.7 ± 0.6 × 109M-1s-1at pH=10. The rate coefficient determined for LA ozonolysis was 4.2 ± 0.2 × 104M-1s-1at pH=2. Calculated Henry’s Law constant (H) for LA was ca. 6.3 × 106M × atm-1thereby indicating that in fogs and clouds with LWC = 0.3-0.5 g × m-3LA will reside entirely in the aqueous-phase. Calculated atmospheric lifetimes due to reaction with OH and O3strongly indicate that aqueous-phase oxidation can be important for LA under realistic atmospheric conditions. Under acidic conditions, the aqueous-phase oxidation of LA by OH will dominate over reaction with O3, whereas the opposite is more likely when pH ≥ 4.5. The aqueous-phase oxidation of LA produced keto-limononic acid and a number of low-volatility products, such as hydroperoxy-LA and α-hydroxyhydroperoxides.

Concepts: Mass spectrometry, PH, Electrospray ionization, Tandem mass spectrometry, Coefficient, Constant, Ozone, Henry's law

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Porous chitosan composites using CO2 dissolution procedure and including water soluble N-propylphosphonic chitosan derivative (p-CHI) were obtained and characterized. In contrast to the control material, composites containing modified chitosan distinguished by a rapid moisture absorption and good adhesion to the skin. The FTIR analysis confirmed the presence of propylphosphonic group in the structure of the polymer. The porosity of the materials was in the range 55-77% and decreased with increasong amount of modified chitosan in materials. Solubility of composites was dependent on the content of p-CHI in scaffolds (40%, 25% and 15%) and reached values 11%, 9% and 6,5%, respectively. The values of other parameters like swelling degree (30g/g) good antioxidant and antimicrobial properties (almost 100% reduction of S.aureus, E.coli and C. albicans growth) and low in vitro cytotoxicity against fibroblasts were highly advantageous for possible biomedical applications of the composites.

Concepts: Carbon dioxide, Solubility, Chemical substance, Solution, Carbonate, Solvation, Bicarbonate, Henry's law

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This study developed a novel method to promote the remediation efficiency of air sparging. According to the enhanced-volatilization theory presented in this study, selected alcohols added to groundwater can highly enhance the volatilization amounts of organic compounds with high Henry’s law constants. In this study, the target organic compounds consisted of n-hexane, n-heptane, benzene, toluene, 1,1,2-trichloroethane, and tetrachloroethene. n-pentanol, n-hexanol, and n-heptanol were used to examine the changes in the volatilization amounts of organic compounds in the given period. Two types of soils with high and low organic matter were applied to evaluate the transport of organic compounds in the soil-water system. The volatilization amounts of the organic compounds increased with increasing alcohol concentrations. The volatilization amounts of the test organic compounds exhibited a decreasing order: n-heptanol>n-hexanol>n-pentanol. When 10mg/L n-heptanol was added to the system, the maximum volatilization enhancement rate was 18-fold higher than that in distilled water. Samples of soil with high organic matter might reduce the volatilization amounts by a factor of 5-10. In the present study, the optimal removal efficiency for aromatic compounds was approximately 98%.

Concepts: Chemistry, Soil, Benzene, Solvent, Aromaticity, Distillation, Electrophilic aromatic substitution, Henry's law