A Comparison of Structure, Stability of Neutral and Cationic Vanadium-doped Germanium Clusters GenV0/+ (n = 2 - 8) by using Density Function Theorym clusters GenV0/+ (n = 2 - 8) by using density function theory

The geometries, stabilities and electronic properties of vanadium-doped germanium clusters GenV0/+ (n=2-8) were systematically investigated by using density functional theory (DFT) at the PBE level and the 6-311+G(d) basis set. The results show that the geometries of lowest-energy structures of the cationic clusters are only significant different from those of the neutral at n = 6 or 7. The ground state of neutral clusters is a doublet, except Ge2V which is a quartet while that of cationic clusters is a triplet, except Ge8V+, which is a singlet. The average binding energy values generally increase with increasing cluster size. The results from average binding energies showed that it is more stable for the cationic than neutral clusters at the same size. Furthermore, the calculated values of fragmentation energy, second-order energy difference, HOMO-LUMO gap and adiabatic ionization potential suggest that the neutral clusters possess higher stability when n = 2, 5, 8 and the cations are more stable when n = 2, 3, 5 and 6.

Advances on the Fragmentation-Energy Fan Concept and the Swebrec Function in Modeling Drop Weight Testing

The breakage index equation (BIE), or t10 model from drop weight testing (DWT) data for rocks and ores is used in the design of crushers and mills. Such models are becoming increasingly difficult to visualize as the number of variables increases. The so-called double fan BIE, combined with the Swebrec distribution’s accurate description of the sieving curves, is applied to the modelling of drop-weight test fragmentation. The key parameters are geometric properties visible in the fan plot; slopes of straight lines and their point of convergence. The ability of the double fan BIE to reproduce DWT data had been previously established for 8 rocks with 480 DWT data sets. Here the fidelity of the double fan BIE is further evaluated for 18 new materials, based on 281 data sets. The fidelity of the double fan BIE with three fan lines is on par with the fidelity of the current state-of-the-art models for the new materials. Besides the breakage index equation, the new double fan BIE’s t10 equation produces, without additional parameters or fitted constants, the general breakage surface equation tn for an arbitrary n value as a bonus. The specific sieving curve for any combination of particle size and impact energy is also contained in the same formula. The result is an accurate, compact and transparent model.

Curvature flows, scaling laws and the geometry of attrition under impacts

Impact induced attrition processes are, beyond being essential models of industrial ore processing, broadly regarded as the key to decipher the provenance of sedimentary particles. Here we establish the first link between microscopic, particle-based models and the mean field theory for these processes. Based on realistic computer simulations of particle-wall collision sequences we first identify the well-known damage and fragmentation energy phases, then we show that the former is split into the abrasion phase with infinite sample lifetime (analogous to Sternberg’s Law) at finite asymptotic mass and the cleavage phase with finite sample lifetime, decreasing as a power law of the impact velocity (analogous to Basquin’s Law). This splitting establishes the link between mean field models (curvature-driven partial differential equations) and particle-based models: only in the abrasion phase does shape evolution emerging in the latter reproduce with startling accuracy the spatio-temporal patterns (two geometric phases) predicted by the former.

Resource Allocation in Space-Division Multiplexing-Based Elastic Optical Networks

This paper presents the work developed in the MSc. thesis entitled ”Resource Allocation in Space-Division Multiplexing-Based Elastic Optical Networks” which explores the resource allocation problem in Space-Division Multiplexing-based Elastic Optical Networks (SDM-EON). The proposed algorithms jointly address spectrum fragmentation, modulation format, crosstalk, and energy consumption. Results demonstrate that our algorithms increase the acceptance of requests for lightpath establishment while handling energy consumption, spectrum fragmentation, energy consumption, load balance, and crosstalk.

LC–MS/MS and GC–MS profiling as well as the antimicrobial effect of leaves of selected Yucca species introduced to Egypt

Few studies thoroughly investigated different Yucca species introduced to Egypt. As a part of our ongoing investigation of the Yucca species; Yucca aloifolia and its variety Yucca aloifolia variegata, Yucca filamentosa, and Yucca elephantipes (Asparagaceae) were extensively subjected to phytochemical and antimicrobial investigation. Yucca species cultivated in Egypt showed no antimicrobial effect. GC/MS of the lipoid contents of Y. aloifolia variegata was carried out. Twenty-six fatty acids were identified. Saturated fatty acids established almost twice the unsaturated ones and constituted 64.64% of which palmitic acid and palmitoleic acid signifying 58.28% and 30.98%, respectively. Hydrocarbons were 21 constituting 39.64% of the unsaponifiable fraction. Only three sterols 42.36% were detected, major was γ-sitosterol. LC–MS/MS comparison of the 4 plant extracts imply that Y.aloifolia variegata L extract was the richest, which was apparent through its superior biological activity. LC–MS/MS analysis of the total alcoholic extract (Alc) of the leaves of Y.aloifolia variegata L. was performed using MS-techniques at different voltages; equal to 35 and 135 eV. Negative and positive-ion modes analyses at low fragmentation energy allowed the tentative identification of 41 and 34 compounds, respectively. The LC–ESI–MS/MS analysis in the positive mode proved to be better in the identification of saponins.

Effect of Water-Decked Blasting on Rock Fragmentation Energy

Fragmentation energy ratio is an important index to evaluate whether an explosive is used efficiently. This paper discusses the effect of water-decked blasting on fragmentation energy based on theory and numerical simulation, and three blasting tests were performed to measure the actual fragmentation energy at a granite-based field. Results show that at the same charge amount, the maximum borehole pressure of water-decked blasting is much greater than that of normal blasting in theory, which facilitates rock breaking. In numerical simulation, water-decked blasting is more beneficial to the transmission of explosive energy; therefore, the damage distribution is more uniform and the damage level is higher. The specific surface area and fragment size distribution were obtained by three-dimensional laser scanning and image analysis in field tests; therefore, the fragmentation energy could be measured, which showed that the fragmentation energy could be increased by 10% in water-decked blasting. In addition, water-decked blasting can reduce fly rocks and ensure the safety of rock blasting.

Investigation on Structural, Relative Stable, and Electronic Properties of Binary AlnLin (n = 2 – 12) Clusters through Density Functional Theory

In the present research, the structural, the relative stable, and the electronic properties of AlnLin (n = 2 – 12) clusters were investigated by density functional theory (DFT). By comparing the calculated values of Al2 and Li2 dimers with experimental ones, the reliability of the proposed method was proved. Furthermore, by considering the values of average binding energy (Eb), vertical ionization potential (VIP), vertical electron affinity (VEA), fragmentation energy (△E), second-order energy difference (△2E), HOMO-LUMO (HL) gap, and chemical hardness (η) were calculated. It was found Fragmentation energy, second-order energy difference, VIP, VEA, the chemical stability and HOMO-LUMO gap exhibit odd-even oscillatory behaviours along with cluster size and have extreme values at n = 5 revealed Al5Li5 cluster yielded excellent stability. Those can be well explained by the density of states (DOS) that Li and Al atoms with stronger covalent bonds. Therefore, Al5Li5 cluster can be used as an ideal candidate for calculating Wilson parameters of Al-Li alloys.

Theoretical study of the geometrical and electronic properties of Be2Mg+ n (n = 1–11) clusters

By using Density Functional Theory (DFT) method at the B3LYP/6-311G level, the structures, stabilities, and electronic properties of cationic Be2Mg+ n (n = 1–11) clusters have been systematically studied. The optimized geometry show that the ground state structures of cationic Be2Mg+ n (n = 1–11) clusters favor 3D structures except n = 1, 2. Furthermore, the average binding energy E b, the second-order energy differences Δ2E, the fragmentation energy Ef and the HOMO-LUMO energy Egap of the ground state of cationic Be2Mg– n (n = 1–11) clusters are calculated, the final results indicate that Be2Mg+6 and Be2Mg+9 clusters have a higher stability than other clusters. Additionally, the NCP, NEC and Mulliken population analysis reveal that the charges in cationic Be2Mg+ n (n = 1–11) clusters transfer from Mg atom to Be atoms, and strong sp hybridizations are presented in Be atoms of Be2Mg+ n clusters. Finally, the polarizability analysis indicates that the nuclei and electronic clouds of clusters are affected by external field with the increase of cluster size.

Structures and stability of closo-hydroborate dianions BnHn2– (n = 5-12) from the PSM model

In this theoretical study, the structures and energetic properties of several closohydroborate dianions BnHn2– (n = 5-12) were systematically investigated employing the B3LYP functional in conjunction with the aug-cc-pVTZ basis set. Global equilibrium geometries were determined, and the growth mechanism is established. Several thermodynamic parameters including the one-step fragmentation energy, the second-order difference in energy, and the HOMO– LUMO energy gap were also computed to evaluate their stability pattern. Computed results show that among investigated species B6H62– and B12H122– are exceptionally stable with closed-shell electronic structures. Their valence electrons generate magic numbers which could be understood by using the phenomenological shell model. The B6H62– with 26 itinerant electrons has an octahedral form ground state (Oh symmetry) and a closed electronic configuration, i.e. 1S2/1P6/2S2/1D10/2P6. Similarly, the anion B12H122– with 50 mobile electrons, which favors an icosahedron (Ih symmetry), also has a closed 1S2/1P6/2S2/1D10/2P6/1F14/2D10 electron shell. Therefore, these systems bear the highly symmetric conformations and constitute the exceedingly stable members of the series examined.