Brown Carbon (BrC) aerosols scatter and absorb solar radiation, directly affecting the Earth's radiative budget. However, considerable uncertainty exists concerning the chemical mechanism leading to BrC formation and their optical properties. In this work, BrC particles were prepared from mixtures of small alpha-dicarbonyls (glyoxal and methylglyoxal) and amines (methylamine, dimethylamine, and trimethylamine). The absorption and scattering of BrC particles were measured using a photoacoustic extinctometer (405 and 532 nm), and the chemical composition of the alpha-dicarbonyl-amine mixtures was analyzed using orbitrap-mass spectrometry and thermal desorption-ion drift-chemical ionization mass spectrometry. The single scattering albedo for methylglyoxal-amine mixtures is smaller than that of glyoxal-amine mixtures and increases with the methyl substitution of amines. The mass absorption cross-section for methylglyoxal-amine mixtures is two times higher at 405 nm wavelength than that at 532 nm wavelength. The derived refractive indexes at the 405 nm wavelength are 1.40-1.64 for the real part and 0.002-0.195 for the imaginary part. Composition analysis in the alpha-dicarbonyl-amine mixtures reveals N-heterocycles as the dominant products, which are formed via multiple steps involving nucleophilic attack, steric hindrance, and dipole dipole interaction between alpha-dicarbonyls and amines. BrC aerosols, if formed from the particle-phase reaction of methylglyoxal with methylamine, likely contribute to atmospheric warming.
In this paper, the thermodynamic phase behaviour of pure and mixing nanoconfined fluids in shale reservoirs are studied. First, an analytical generalized equation of state (EOS) is developed by including the effects of pore radius and intermolecular interactions. Based on the generalized EOS, four extended cubic EOS are proposed and used to calculate the thermodynamic phase behaviour. The four extended cubic EOSs, the extended van der Waals (vdW), Redlich−Kwong (RK), Soave−Redlich−Kwong (SRK), and Peng−Robinson (PR) EOSs, are found to accurately predict the pressure–volume (P–V) diagrams of different systems in nanopores. More specifically, the extended RK (E-RK) EOS may fail to accurately calculate the phase behaviour at high temperatures and the extended PR (E-PR) EOS is more accurate for liquid phase pressure calculations. The overall calculated P–V diagrams for the pure components in nanopores from the extended EOS shift up and right relative to those of the bulk-phase case and the EOS only including the intermolecular interactions. Furthermore, as a physical meaningless phenomenon, the negative pressure state is completely avoided in the calculated P-V diagrams from the extended EOSs. Compared to the measured bubble-point pressure (Pb) for the four different confined mixing fluids, the E-vdW, E-RK, and E-SRK EOS provide accurate estimates of Pb with overall percentage average absolute deviations (AAD%) of 10.95%, 12.07%, and 9.37%, respectively. The proposed extended EOSs are capable to accurately predict the critical properties and their shifts in nanopores. A bottom limit for the continuous reduction of the critical properties by decreasing the pore radius is obtained from the proposed extended EOSs, which is, for example, 5 nm for C8H18.
On the basis of Nāgārjuna’s works, especially the Mūlamadhyamakakārikā, this paper proposes a sceptic presupposition as the departure point of Nāgārjuna’s refutations. This presupposition invalidates perceptual knowledge, and thus the identities of existents (svabhāva) can only be deemed as referents assumed by concepts (nāman, vikalpa, etc.). Then the “confinement principle,” a theorem tacitly applied in Nāgārjuna’s arguments, is justified, i.e., any definition or description of a concept would necessarily confine its assumed referent to an invariable and isolated state. This principle enables Nāgārjuna to deduce contradictions between the static and isolated nature of the assumed referent, and the activity in which it must be involved. Notions of both a static identity and its activity are deep-rooted in all referential mental activities of sentient beings. Hence all concepts are found to be self-contradictory and therefore devoid of referents (niḥsvabhāva), namely, empty (śūnya). Thus, Nāgārjuna is refuting the whole intelligible world, and his position can be identified as epistemological nihilism—nothing within our ken can possibly be