Remarkable Size Effect on Photophysical and Nonlinear Optical Properties of All-Carboatomic Rings, Cyclo[18]carbon and Its Analogues

Inspired by recent experimental observation of molecular morphology and theoretical predictions of multiple properties of cyclo[18]carbon, we systematically studied photophysical and nonlinear optical properties of cyclo[2<i>N</i>]carbons (<i>N</i> = 3−15) allotropes through density functional theory. This work unveils the unusual optical properties of the sp-hybridized carbon rings with different sizes. The remarkable size dependence of optical properties of these systems and its underlying natures are profoundly explored, and the relevance between aromaticity and optical properties are highlighted. The extrapolation curves fitted for energy level of frontier molecular orbitals, maximum absorption wavelength, and (hyper)polarizability of considered carbon rings are presented, which can be used to reliably predict corresponding properties for arbitrarily large rings. The findings in this study will facilitate the exploration of potential application of the cyclocarbons in the field of optical material.

Coupling large and small ring infiltration experiments for investigating preferential flow

&lt;p&gt;Preferential flow is more the rule than the exception. Water infiltration is often led by preferential flow due to macropores, specific soil structures (e.g., aggregates, macropore networks), or lithological heterogeneity (occurrence of materials with contrasting hydraulic properties). Water infiltration in soils prone to preferential flow strongly depends on soil features below the soil surface, but also the initiation of water infiltration at the surface. When the macropore networks are not dense, with only a few macropores intercepting the soil surface, water infiltration experiments with ring size in the order of 10-15 cm diameter may overlook sampling macropore networks during some infiltration runs, minimizing the effect of macropore flow on the bulk water infiltration at the plot scale.&lt;/p&gt;&lt;p&gt;In this study, we investigated the effect of ring size on water infiltration into soils prone to preferential flow. We used two ring sizes: small (15 cm in diameter) and large (50 cm in diameter). By doing so, we hypothesized that the large rings, sampling a more representative soil volume, will maximize the probability to intercept and activate a macropore network. In contrast, the small rings may activate the macropore network only occasionally, with other infiltration runs mainly sampling the soil matrix. Thus, the small rings are expected to provide more variable results. On the other hand, the large rings are expected to provide more homogeneous results in line with the soil's bulk infiltration capability, including all pore networks at the plot scale.&lt;/p&gt;&lt;p&gt;Three different sites were sampled with varying types of preferential flow (macropore-induced versus lithological heterogeneity induced). The experimental plan included inserting large rings at several places in the experimental sites with a dozen small rings nearby to sample the same soil. All the rings were submitted to a similar positive constant water pressure head at the soil surface. The cumulative infiltrations were then monitored and treated with BEST algorithms to get the efficient hydraulic parameters. Note that the cumulative infiltration could not be compared directly since lateral water fluxes varied in extent and geometry between the different ring sizes. The impacts of the ring size on the magnitude of cumulative infiltration and related estimated hydraulic parameters were discussed. Our results demonstrated the impact of ring size but also the dependency of such effect on the site and the type of flow.&lt;/p&gt;&lt;p&gt;Our results contribute to understanding preferential flow in heterogeneous soils and the complexity of its measure using regular water infiltration devices and protocols.&lt;/p&gt;

Remarkable Size Effect on Photophysical and Nonlinear Optical Properties of All-Carboatomic Rings, Cyclo[18]carbon and Its Analogues

Inspired by recent experimental observation of molecular morphology and theoretical predictions of multiple properties of cyclo[18]carbon, we systematically studied photophysical and nonlinear optical properties of cyclo[2<i>N</i>]carbons (<i>N</i> = 3−15) allotropes through density functional theory. This work unveils the unusual optical properties of the sp-hybridized carbon rings with different sizes. The remarkable size dependence of optical properties of these systems and its underlying natures are profoundly explored, and the relevance between aromaticity and optical properties are highlighted. The extrapolation curves fitted for energy level of frontier molecular orbitals, maximum absorption wavelength, and (hyper)polarizability of considered carbon rings are presented, which can be used to reliably predict corresponding properties for arbitrarily large rings. The findings in this study will facilitate the exploration of potential application of the cyclocarbons in the field of optical material.

Remarkable Size Effect on Photophysical and Nonlinear Optical Properties of All-Carboatomic Rings, Cyclo[18]carbon and Its Analogues

Inspired by recent experimental observation of molecular morphology and theoretical predictions of multiple properties of cyclo[18]carbon, we systematically studied photophysical and nonlinear optical properties of cyclo[2<i>N</i>]carbons (<i>N</i> = 3−15) allotropes through density functional theory. This work unveils the unusual optical properties of the sp-hybridized carbon rings with different sizes. The remarkable size dependence of optical properties of these systems and its underlying natures are profoundly explored, and the relevance between aromaticity and optical properties are highlighted. The extrapolation curves fitted for energy level of frontier molecular orbitals, maximum absorption wavelength, and (hyper)polarizability of considered carbon rings are presented, which can be used to reliably predict corresponding properties for arbitrarily large rings. The findings in this study will facilitate the exploration of potential application of the cyclocarbons in the field of optical material.

Curvature instability of a curved Batchelor vortex

In this paper, we analyse the curvature instability of a curved Batchelor vortex. We consider this short-wavelength instability when the radius of curvature of the vortex centreline is large compared with the vortex core size. In this limit, the curvature instability can be interpreted as a resonant phenomenon. It results from the resonant coupling of two Kelvin modes of the underlying Batchelor vortex with the dipolar correction induced by curvature. The condition of resonance of the two modes is analysed in detail as a function of the axial jet strength of the Batchelor vortex. In contrast to the Rankine vortex, only a few configurations involving $m=0$ and $m=1$ modes are found to become the most unstable. The growth rate of the resonant configurations is systematically computed and used to determine the characteristics of the most unstable mode as a function of the curvature ratio, the Reynolds number and the axial flow parameter. The competition of the curvature instability with another short-wavelength instability, which was considered in a companion paper (Blanco-Rodríguez & Le Dizès, J. Fluid Mech., vol. 804, 2016, pp. 224–247), is analysed for a vortex ring. A numerical error found in this paper, which affects the relative strength of the elliptic instability, is also corrected. We show that the curvature instability becomes the dominant instability in large rings as soon as axial flow is present (vortex ring with swirl).

An electronic aromaticity index for large rings

We introduce a new electronic aromaticity index, AV1245, consisting of an average of the 4-center indices along the ring that keep a positional relationship of 1, 2, 4, 5.

A co-crystal of nonahydrated disodium(II) with mixed anions fromm-chlorobenzoic acid and furosemide

In the title compound, [Na2(H2O)9](C7H4ClO2)(C12H10ClN2O5S) {systematic name:catena-poly[[[triaquasodium(I)]-di-μ-aqua-[triaquasodium(I)]-μ-aqua] 3-chlorobenzoate 4-chloro-2-[(furan-2-ylmethyl)amino]-5-sulfamoylbenzoate]}, both the originalm-chlorobenzoic acid and furosemide exist with deprotonated carboxylates, and the sodium cations and water molecules exist in chains with stoichiometry [Na2(OH2)9]2+that propagate in the [-110] direction. Each of the two independent Na+ions is coordinated by three monodentate water molecules, two double-water bridges, and one single-water bridge. There is considerable cross-linking between the [Na2(OH2)9]2+chains and to furosemide sulfonamide and carboxylate by intermolecular O—H...O hydrogen bonds. All hydrogen-bond donors participate in a complex two-dimensional array parallel to theabplane. The furosemide NH group donates an intramolecular hydrogen bond to the carboxylate group, and the furosemide NH2group donates an intramolecular hydrogen bond to the Cl atom and an intermolecular one to them-chlorobenzoate O atom. The plethora of hydrogen-bond donors on the cation/water chain leads to many large rings, up to graph setR44(24), involving two chains and two furosemide anions. The chlorobenzoate is involved in only oneR22(8) ring, with two water moleculescis-coordinated to Na. The furan O atom is not hydrogen bonded.