Temperature-Dependent Henry’s Law Constants of Atmospheric Amines Leng, Chunbo; Kish, J. Duncan; Roberts, Jason E ...
The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory,
08/2015, Volume:
119, Issue:
33
Journal Article
Peer reviewed
There has been growing interest in understanding atmospheric amines in the gas phase and their mass transfer to the aqueous phase because of their potential roles in cloud chemistry, secondary ...organic aerosol formation, and the fate of atmospheric organics. Temperature-dependent Henry’s law constants (K H) of atmospheric amines, a key parameter in atmospheric chemical transport models to account for mass transfer, are mostly unavailable. In this work, we investigated gas–liquid equilibria of five prevalent atmospheric amines, namely 1-propylamine, di-n-propylamine, trimethylamine, allylamine, and 4-methylmorpholine using bubble column technique. We reported effective K H, intrinsic K H, and gas phase diffusion coefficients of these species over a range of temperatures relevant to the lower atmosphere for the first time. The measured K H at 298 K and enthalpy of solution for 1-propylamine, di-n-propylamine, trimethylamine, allylamine, and 4-methylmorpholine are 61.4 ± 4.9 mol L–1 atm–1 and −49.0 ± 4.8 kJ mol–1; 14.5 ± 1.2 mol L–1 atm–1 and −72.5 ± 6.8 kJ mol–1; 8.9 ± 0.7 mol L–1 atm–1 and −49.6 ± 4.7 kJ mol–1; 103.5 ± 10.4 mol L–1 atm–1 and −42.7 ± 4.3 kJ mol–1; and 952.2 ± 114.3 mol L–1 atm–1 and −82.7 ± 9.7 kJ mol–1, respectively. In addition, we evaluated amines’ characteristic times to achieve gas–liquid equilibrium for partitioning between gas and aqueous phases. Results show gas–liquid equilibrium can be rapidly established at natural cloud droplets surface, but the characteristic times may be extended substantially at lower temperatures and pHs. Moreover, our findings imply that atmospheric amines are more likely to exist in cloud droplets, and ambient temperature, water content, and pH of aerosols play important roles in their partitioning.
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IJS, KILJ, NUK, PNG, UL, UM
3.
Impacts of Micro-credit on Household Economics TENG, SIVCHOU; PRIEN, SOKHAK; MAO, NARA ...
International Journal of Environmental and Rural Development,
2011, Volume:
2, Issue:
1
Journal Article
Peer reviewed
Open access
This research was conducted to investigate the impacts of micro-credit on local household economics in Prek Norin Commune by focusing on people who took a loan from microfinance institutions and ...continue to use it. This study mainly focuses on three objectives, socio-economic factors of households using credit, the status of using micro-credit and effects of micro-credit on household economics. Data were collected via survey, using face to face interviews with a hundred and forty two household heads. Simple random sampling method was used to select the samples from two villages (Prektachreng and Prek Krouch) in Prek Norin Commune, Ek Phnom district, Battambang province. Therefore, the accuracy of the analysis heavily relies on the data provided by interviewees. The result of this study revealed that those using micro-credit have better living standards than before because of income and asset growth. In addition, using micro-credit also creates more job opportunities and variety of economic activities, provides more jobs for women, and improves household education, women's status, and family welfare. It also reduces income inequality in the villages. However, micro-credit has negative impacts on people's feeling because most people are more concerned about paying back the loan.
In Salmonella typhimurium, expression of the hisR locus, a tRNA operon, decreases upon inhibiting DNA gyrase. Here, the hisR promoter dependence on negative DNA supercoiling was examined in vivo and ...in vitro. Mutant analysis showed the sequence determinants of this dependence to lie in the region between the −10 box and the transcription start site. As with most promoters subject to stringent control, this portion of the hisR promoter is C–G‐rich. Replacing a C/G bp with T/A at position −7 partially relieves the supercoiling response while changing the sequence between −5 and +1 (‐CCCCCG‐) for ‐GTTAA‐ abolishes the response in vitro and in vivo. The relief of the supercoiling dependence closely correlates with increased promoter susceptibility to melting in vivo and a lesser requirement for initiating nucleotides in the formation of stable initiation complexes in vitro. Studies in isoleucine‐starved cells showed that such sequence changes mitigate and abolish the hisR promoter response to stringent control, respectively. The data presented suggest that the hisR promoter's sensitivity to stringent regulation arises from the same physical property that confers supercoiling sensitivity, i.e. resistance to melting. We propose that the stringent control mechanism acts by hampering the ability of RNA polymerase to melt the DNA helix.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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