Inversion using a new low-dimensional representation of complex binary geological media based on a deep neural network

Efficient and high-fidelity prior sampling and inversion for complex geological media is still a largely unsolved challenge. Here, we use a deep neural network of the variational autoencoder type to construct a parametric low-dimensional base model parameterization of complex binary geological media. For inversion purposes, it has the attractive feature that random draws from an uncorrelated standard normal distribution yield model realizations with spatial characteristics that are in agreement with the training set. In comparison with the most commonly used parametric representations in probabilistic inversion, we find that our dimensionality reduction (DR) approach outperforms principle component analysis (PCA), optimization-PCA (OPCA) and discrete cosine transform (DCT) DR techniques for unconditional geostatistical simulation of a channelized prior model. For the considered examples, important compression ratios (200 - 500) are achieved. Given that the construction of our parameterization requires a training set of several tens of thousands of prior model realizations, our DR approach is more suited for probabilistic (or deterministic) inversion than for unconditional (or point-conditioned) geostatistical simulation. Probabilistic inversions of 2D steady-state and 3D transient hydraulic tomography data are used to demonstrate the DR-based inversion. For the 2D case study, the performance is superior compared to current state-of-the-art multiple-point statistics inversion by sequential geostatistical resampling (SGR). Inversion results for the 3D application are also encouraging

DFT Studies on Copper-Catalyzed Arylation of Aromatic C–H Bonds

Cu-catalyzed arylation of aromatic C–H bonds with phenyl iodide has been investigated with the aid of density functional theory calculations at the B3LYP level. Both the neutral and anionic catalytic cycles have been examined by considering the neutral (phen)­Cu–OMe and anionic [MeO–Cu–OMe]⁻ complexes, respectively, as the active species. Various heterocycle and polyfluorobenzene substrates were studied. The relationship between the overall reaction barrier and the acidity of the cleaved C–H bond was studied in both the neutral and anionic catalytic cycles. Comparing the overall reaction barriers based on the neutral and anionic catalytic cycles, we were able to understand that some substrates prefer the anionic mechanism while others prefer the neutral mechanism. We also examined how different ligands influence the overall barriers in the neutral catalytic cycles by employing <i>N</i>,<i>N</i>′-dimethylethylenediamine (DMEDA) and <i>N</i>-methylpyrrolidine-2-carboxamide as the ligands

Plots of variable importance projection (VIP) scores (solid curves) and <i>b</i>-coefficients (dashed curves) associated with the PLSR cross-validation model for organic matter content of the soil samples in Yujiang County of Jiangxi Province, China.

<p>The threshold for the VIP was set to 1 (solid horizontal line) and the thresholds for the <i>b</i>-coefficients were based on their standard deviation (σ = 52.4) (dashed horizontal lines).</p

Correlation of the organic matter content of the soil samples in Yujiang County of Jiangxi Province, China with the original reflectance and the first derivative of the original reflectance (n = 232) at different wavelengths.

<p>Correlation of the organic matter content of the soil samples in Yujiang County of Jiangxi Province, China with the original reflectance and the first derivative of the original reflectance (n = 232) at different wavelengths.</p

DFT Studies on Cu-Catalyzed Cross-Coupling of Diazo Compounds with Trimethylsilylethyne and <i>tert</i>-Butylethyne: Formation of Alkynes for Trimethylsilylethyne while Allenes for <i>tert</i>-Butylethyne

The detailed reaction mechanism for the Cu­(I)-catalyzed cross-coupling of (diazomethyl)­benzene with trimethylsilylethyne and <i>tert</i>-butylethyne was studied with the aid of density functional theory calculations. For both reactions, two catalytic cycles were considered. In one catalytic cycle, the active species reacts first with trimethylsilylethyne or <i>tert</i>-butylethyne, whereas, in the other one, the active species reacts first with (diazomethyl)­benzene. In both catalytic cycles, the copper acetylide formation, copper carbene migratory insertion, and protonation steps are involved. The calculation results show that the protonation step is crucial for the product selectivity. In addition, the reaction of diazoethane with <i>tert</i>-butylethyne and the reaction of (diazomethyl)­benzene with phenylacetylene were also considered theoretically

Statistical characteristics of soil physicochemical variables for soil samples developed from different parent materials in Yujiang County of Jiangxi Province, China.

<p>Statistical characteristics of soil physicochemical variables for soil samples developed from different parent materials in Yujiang County of Jiangxi Province, China.</p

Statistical characteristics of the organic matter content of soil samples developed from different parent materials in Yujiang County of Jiangxi Province, China.

<p>Statistical characteristics of the organic matter content of soil samples developed from different parent materials in Yujiang County of Jiangxi Province, China.</p

Synthesis of Heterocyclic-Fused Cyclopentadienyl Scandium Complexes and the Catalysis for Copolymerization of Ethylene and Dicyclopentadiene

Heterocyclic-fused cyclopentadienyl scandium bis­(alkyl) complexes <b>L</b>^{<b>1</b>–<b>4</b>}Sc­(CH₂SiMe₃)₂THF ((5-Me-1-Ph-cyclopenta­[<i>b</i>]­pyrrol-4-yl)­Sc­(CH₂SiMe₃)₂THF (<b>1</b>), (2,5-Me₂-3-Ph-6<i>H</i>-cyclopenta­[<i>b</i>]­thiophenyl)­Sc­(CH₂SiMe₃)₂THF (<b>2</b>), (2,4,5,6-Me₄-4<i>H</i>-cyclopenta­[<i>b</i>]­thiophenyl)­Sc­(CH₂SiMe₃)₂THF (<b>3</b>), (2,3,4,5,6-Me₅-4<i>H</i>-cyclopenta­[<i>b</i>]­thiophenyl)­Sc­(CH₂SiMe₃)₂THF) (<b>4</b>)) were facilely synthesized by alkane elimination reaction of Sc­(CH₂SiMe₃)₃(THF)₂ with the heterocyclic-fused cyclopentadienyl ligands <b>HL</b>^{<b>1</b>–<b>4</b>} in high yields. Complexes <b>1</b>–<b>4</b> were characterized by ¹H and ¹³C NMR spectroscopies and X-ray diffraction analyses as THF-solvated monomers, adopting a half-sandwich geometry. Upon activation of [Ph₃C]­[B­(C₆F₅)₄]/Al^<i>i</i>Bu₃, these half-sandwich scandium complexes displayed various activities toward the copolymerization of ethylene (E) and dicyclopentadiene (DCPD). Complex <b>1</b>, supported by the phenyl-substituted pyrrole-fused cyclopentadienyl ligand, showed a slightly higher activity than the phenyl-substituted thiophene-fused cyclopentadienyl complex <b>2</b>. Among the thiophene-fused cyclopentadienyl complexes <b>2</b>–<b>4</b>, <b>4</b>, bearing pentamethyl substituents, showed the highest activity of 2.9 × 10⁶ g/mol_Sc·h·bar. The resultant copolymers had adjustable DCPD incorporation varying from 14.0 up to 46.1 mol %, of which the alternating poly­(E-<i>alt</i>-DCPD) had a high <i>T</i>_g of 166 °C. In addition, no cross-linking was observed in the copolymers, suggesting that these catalytic systems were highly regioselective for the two active double bonds within DCPD

Synthesis of Heterocyclic-Fused Cyclopentadienyl Scandium Complexes and the Catalysis for Copolymerization of Ethylene and Dicyclopentadiene

Heterocyclic-fused cyclopentadienyl scandium bis­(alkyl) complexes <b>L</b>^{<b>1</b>–<b>4</b>}Sc­(CH₂SiMe₃)₂THF ((5-Me-1-Ph-cyclopenta­[<i>b</i>]­pyrrol-4-yl)­Sc­(CH₂SiMe₃)₂THF (<b>1</b>), (2,5-Me₂-3-Ph-6<i>H</i>-cyclopenta­[<i>b</i>]­thiophenyl)­Sc­(CH₂SiMe₃)₂THF (<b>2</b>), (2,4,5,6-Me₄-4<i>H</i>-cyclopenta­[<i>b</i>]­thiophenyl)­Sc­(CH₂SiMe₃)₂THF (<b>3</b>), (2,3,4,5,6-Me₅-4<i>H</i>-cyclopenta­[<i>b</i>]­thiophenyl)­Sc­(CH₂SiMe₃)₂THF) (<b>4</b>)) were facilely synthesized by alkane elimination reaction of Sc­(CH₂SiMe₃)₃(THF)₂ with the heterocyclic-fused cyclopentadienyl ligands <b>HL</b>^{<b>1</b>–<b>4</b>} in high yields. Complexes <b>1</b>–<b>4</b> were characterized by ¹H and ¹³C NMR spectroscopies and X-ray diffraction analyses as THF-solvated monomers, adopting a half-sandwich geometry. Upon activation of [Ph₃C]­[B­(C₆F₅)₄]/Al^<i>i</i>Bu₃, these half-sandwich scandium complexes displayed various activities toward the copolymerization of ethylene (E) and dicyclopentadiene (DCPD). Complex <b>1</b>, supported by the phenyl-substituted pyrrole-fused cyclopentadienyl ligand, showed a slightly higher activity than the phenyl-substituted thiophene-fused cyclopentadienyl complex <b>2</b>. Among the thiophene-fused cyclopentadienyl complexes <b>2</b>–<b>4</b>, <b>4</b>, bearing pentamethyl substituents, showed the highest activity of 2.9 × 10⁶ g/mol_Sc·h·bar. The resultant copolymers had adjustable DCPD incorporation varying from 14.0 up to 46.1 mol %, of which the alternating poly­(E-<i>alt</i>-DCPD) had a high <i>T</i>_g of 166 °C. In addition, no cross-linking was observed in the copolymers, suggesting that these catalytic systems were highly regioselective for the two active double bonds within DCPD

Tests of independent means in comparing effects of the lack and presence of depressive emotion on the care burden of informal caregivers and quality of life of disabled elders.

<p>Tests of independent means in comparing effects of the lack and presence of depressive emotion on the care burden of informal caregivers and quality of life of disabled elders.</p