Diamond has the highest number density (i.e., of atoms per unit volume) all known substances and a remarkably high valence electron ($r$${}_{\mathit{ws}}$ $=$ 0.697 \AA{}). Searching for possible superdense carbon allotropes, we have found three structures ($h$P3, $t$I12, $t$P12) that significantly greater density. The $h$P3 $t$P12 phases strong analogy with two polymorphs silica ($\ensuremath{\beta}$-quartz keatite), while $t$I12 phase is related to high-pressure SiS${}_{2}$ polymorph....

In a scenario of increasing globalization, sustainable development has emerged as an attractive and strategic issue for both countries individual organizations their supply chains. Companies have faced different challenges in seeking to combine the best economic performance with increased social environmental responsibility. Monitoring sustainability is essential decision-making management activities that comprise organization’s system processes. Evaluation can be performed using indices or...

2D MoSe2 nanosheets were investigated as a catalyst for nitroarene reduction in the context of water treatment and demonstrated to exhibit higher activity than their more studied MoS2 counterpart. Density functional theory (DFT) calculations disclosed feasible pathway on MoSe2, which involved passivation active site by oxygen from nitro group its reactivation reducing hydride. DFT analysis also provided an explanation isomer selectivity displayed (towards, e.g., 2-, 3- 4-nitroaniline). To...

An experimental study was carried out in rats with the purpose of demonstrating capacity pulsed electromagnetic fields (PEMFs) to stimulate regeneration peripheral nervous system (PNS). Wistar and Brown Norway (BN) were used. Direct sciatic nerve anastomoses performed after section or allograft interposition. Treatment groups then received 4 weeks PEMFs. Control no stimulation. The evaluation results by quantitative morphometric analysis, a statistically significant increase indices (P <...

Uniaxial [001] stress induces a semiconductor–metal transition in 3C-SiC.

Two distinct points on the potential energy curve (PEC) of a pairwise interaction, zero-energy crossing point and where stretching force constant vanishes, allow us to anticipate range possible distances between two atoms in diatomic, molecular moieties crystalline systems. We show that these bond-stability boundaries are unambiguously defined correlate with topological descriptors electron-density-based scalar fields, can be calculated using generic PECs. Chemical databases...

Microcrystals of (NH4)2Ce(PO4)2·H2O were hydrothermally obtained from a CeO2−CO(NH2)2−H3PO4−H2O system (T = 180 °C). The structure [orthorhombic, Imma, 6.8940(9), b 6.8860(9), c 17.723(2) Å] consists CeO8 distorted dodecahedra and PO4 tetrahedra joined together to form three-dimensional framework with small four-sided larger six-sided tunnels in quasi-equivalent directions. Ammonium ions water molecules are situated inside the tunnels. Also, thermal decomposition is discussed.

The characterization of bonding interactions in molecules and materials is one the major applications quantum mechanical calculations. Numerous schemes have been devised to identify visualize chemical bonds, including electron localization function, theory atoms molecules, natural bond orbital analysis, whereas energetics formation are generally analyzed qualitative terms through various forms energy partitioning schemes. In this Article, we illustrate how pressure (CP) approach recently...

The crystal structure of many inorganic compounds can be understood as a metallic matrix playing the role host lattice in which nonmetallic atomic constituents are located, Anions Metallic Matrices (AMM) model stated. power and utility this lie its capacity to anticipate actual positions guest atoms crystals using only information known from metal structure. As pertinent test-bed for AMM model, we choose set common phases along with other nonconventional or more complex structures...

Subvalent compounds raise the question of where those valence electrons not belonging to chemical bonds are. In limiting case Ag

The interplay of structural, energetic, and chemical bonding features across the pressure-induced α-cristobalite → stishovite phase transition in SiO2 is fully characterized by first principles calculations topological analysis electron localization function. Under a martensitic approach, mechanism theoretically modeled at thermodynamic pressure using P41212 space group. A soft symmetric path determined with an activation barrier lower than 100 kJ/mol. No bond breaking found, but synchronous...

The complete crystal structures, including H-atom positions, of α-Ti(HPO 4 ) 2 .H O (α-TiP) and α-Hf(HPO (αHfP) were determined by Rietveld refinement Fourier synthesis, using constant-wavelength neutron diffraction data. This work is one few recent examples the determination H atoms powder with an intense source. orientation water molecules in cavities α-TiP similar to that previously found for α-ZrP. For α-HfP, although hydrogen-bonding scheme identical, was be different.

The reaction between 2-aminobuta-1,3-dienes and pentacarbonyl-[1-methoxy-frans-3-(2-furyl)-prop-2-enylidene]-chromium(0) takes place at room temperature leading with total regio- stereo-selectivity to functionalized seven-membered carbocycles good yields.

Microcrystals of the first ammonium-thorium phosphates, (NH 4) 2Th(PO 2.H 2O (tetragonal, I4 1/ amd, a = 7.0192(4) A, c 17.9403(8) A) and NH 4Th 2(PO 3 (monoclinic, C2/ c, 17.880(6) b 6.906(1) 8.152(2) beta 104.39(2) degrees ) were hydrothermally obtained from Th(NO 3) 4-CO(NH 2) 2-H 3PO 3-H system ( T 180 C). In both cases, structure consists three-dimensional framework with PO 4 tetrahedra coordinated to Th atoms (ThO n polyhedra, where 8 or 9, for tetragonal monoclinic phase,...

The valence shell electron pair repulsion (VSEPR) model is a demanding testbed for modern chemical bonding formalisms. challenge consists in providing reliable quantum mechanical interpretations of how concepts such as bonds, lone pairs, electronegativity, or hypervalence influence (or modulate) molecular geometries. Several schemes have been developed thus far to visualize and characterize these effects; however, the best our knowledge, no scheme has yet incorporated analysis premises...

Th(2)(PO(4))(2)(HPO(4)).H(2)O was synthesized under wet hydrothermal conditions starting from a mixture of H(3)PO(3) and Th(NO(3))(4).5H(2)O. The crystal structure solved by powder X-ray diffraction data. unit cell parameters are = 6.7023(8) Angstroms, b 7.0150(8) c 11.184(1) beta 107.242(4) degrees, space group P2(1), Z 2. consists layers both thorium atoms PO(4) groups, alternating with layer formed HPO(4) entities water molecules. By thermal treatment, this compound turns into...

Understanding the stability limit of crystalline materials under variable tensile stress conditions is capital interest for technological applications. In this study, we present results from first-principles density functional theory calculations that quantitatively account response selected covalent and layered to general conditions. particular, have evaluated ideal strength along main crystallographic directions 3C 2H polytypes SiC, hexagonal ABA stacking graphite 2H-MoS 2 . Transverse...

The quest for new transition metal dichalcogenides (TMDs) with outstanding electronic properties operating under ambient conditions draws us to investigate the 1T-HfSe2 polytype hydrostatic pressure. Diamond anvil cell (DAC) devices coupled in situ synchrotron X-ray, Raman, and optical (VIS–NIR) absorption experiments along density functional theory (DFT)-based calculations prove that (i) bulk exhibits strong structural vibrational anisotropies, being interlayer direction especially...

Abstract Two distinct points on the potential energy curve (PEC) of a pairwise interaction, zero‐energy crossing point and where stretching force constant vanishes, allow us to anticipate range possible distances between two atoms in diatomic, molecular moieties crystalline systems. We show that these bond‐stability boundaries are unambiguously defined correlate with topological descriptors electron‐density‐based scalar fields, can be calculated using generic PECs. Chemical databases...

The reaction of diphenylphosphinoferrocene and 1,1′-bis(diphenylphosphino)ferrocene with [Rh2(O2CMe)4(MeOH)2](1:1 1:2 molar ratio respectively) yields the monoadducts [Rh2(O2CMe)4{(Ph2PC5H4)Fe(C5H5)}]1 [{Rh2(O2CMe)4(MeOH)}2{(Ph2PC5H4)2Fe}]2. By thermal treatment 1 in refluxing toluene–acetic acid (10:3) monometallated product [Rh2(O2CMe)3{[(C6H4)PhP(C5H4)]Fe(C5H5)}(HO2CMe)2]3 was obtained practically quantitative yield. Compound 3 reacts [Fe(C5H5)(C5H4PPh2)](1:1 ratio) giving adduct...

The reaction between natural phlogopite, having the idealized formula KMg3(AlSi3O10)(OH)2, and phenylphosphonic acid under soft conditions (24 h, 80 °C, reflux) originated a new layered material of following composition: [Mg(H2O)2]0.5(AlSi3O6)(O3PC6H5)2·2H2O. mechanism involves rupture trioctahedral layers phlogopite formation basal spacing hydrophobic type that is occupied by groups in pseudomonomolecular arrangement. Simultaneously, mobile K+ ions become partially substituted [Mg(H2O)2]2+...