Analysis of anharmonic and thermoelastic properties of non-centrosymmetric crystals

In the present paper an analytical potential form is used for overlap repulsive energy, derived by Harrison from quantum mechanical considerations, along with the composite effect of three-body forces and intersublattice displacement. The short-range overlap parameters in Harrison's potential form have direct correlation with the valence state energies for outermost electrons. The potential model is applied to calculate the third and fourth order elastic constants, first and second pressure derivatives of second order elastic constants, Grüneisen parameter and its volume dependence, Anderson parameter, and thermal expansion coefficient for three non-centrosymmetric crystals, viz. CaF₂, SrF₂ and BaF₂. The calculated values of various physical quantities are found to be in good agreement with experimental data.The authors are grateful to Dr. Mansour Khalef, the Head of Physics Department, TNRC, Tajura (Tripoli) for the facilities and encouragements.     

Regioselective Reaction of N1-Benzyl-N2-(4-nitrophenyl)ethanediamide and Acetylenic Esters

The regioselective reaction of N¹-benzyl-N²-(4-nitrophenyl)ethanediamide with dialkyl acetylenedicarboxylates or alkyl propiolates in the presence of triphenylphosphine leads to dialkyl 4-benzylamino-1-(4-nitrophenyl)-5-oxo-2,5-dihydro-1H-pyrrole-2,3-dicarboxylates or alkyl 4-benzylamino-1-(4-nitrophenyl)-2-oxo-5-pyrrolidinecarboxylates in good yields.     

Diketene-based neat four-component synthesis of the dihydropyrimidinones and dihydropyridine backbones using silica sulfuric acid(SSA)

Heterocyclic skeleton building blocks to afford dihydropyrimidinones and dihydropyridines based on neat adducts of diketene,alcohols and aldehydes via silica sulfuric acid(SSA) catalyzed ring opening of diketene in four-component Biginelli-type and Hantzsch-type reactions are presented.     

Mathematical modeling of a slurry reactor for DME direct synthesis from syngas

In this paper,an axial dispersion mathematical model is developed to simulate a three-phase slurry bubble column reactor for direct synthesis of dimethyl ether(DME) from syngas.This large-scale reactor is modeled using mass and energy balances,catalyst sedimentation andsingle-bubble as well as two-bubbles class flow hydrodynamics.A comparison between the two hydrodynamic models through pilot plantexperimental data from the literature shows that heterogeneous two-bubbles flow model is in better agreement with the experimental data thanhomogeneous single-bubble gas flow model.Also,by investigating the heterogeneous gas flow and axial dispersion model for small bubblesas well as the large bubbles and slurry(i.e.including paraffins and the catalyst) phase,the temperature profile along the reactor is obtained.Acomparison between isothermal and non-isothermal reactors reveals no obvious performance difference between them.The optimum values ofreactor diameter and height were obtained at 7 m and 50 m,respectively.The effects of operating variables on the axial catalyst distribution,DME productivity and CO conversion are also investigated in this research.     

Using a Natural Surfactant for Synthesize of NiO and CuO Nanostructures via Simple and Fast Microwave Approach

NiO and CuO nanostructures were synthesized successfully via simple and fast microwave approach. Olive oil was chose as surfactant for stabilizing nanostructures. Different parameters such as microwave time and power and olive oil concentration were investigated on product size and morphology. The products were characterized with X-ray diffraction pattern, scanning electron microscopy, transmission electron microscopy and energy dispersive spectrometry analysis.     

Application of chromium‐doped fullerene as a carrier for thymine and uracil nucleotides: Comprehensive density functional theory calculations

The interactions of the nucleobases thymine (C₅H₆N₂O₂) and uracil (C₄H₄N₂O₂) with Cr‐doped C₂₀ fullerene (C₁₉Cr) are investigated by performing density functional theory calculations. The adsorption of these nucleobases on C₁₉Cr leads to two distinct geometries (P1 and P2) differing in the orientation of the nucleobases. The interaction of the nucleobases with the C₁₉Cr nanocluster is highly exothermic, revealing that they are chemically adsorbed on C₁₉Cr. The results show that the binding energy of the thymine–C₁₉Cr complex is slightly higher than that of the uracil–C₁₉Cr complex. In addition, the P2 geometry is more stable compared to P1 due to the higher binding energy in the former configuration. However, based on the results of natural bond orbital and frontier molecular orbitals analyses, the C₁₉Cr nanocage has higher reactivity with the nucleobases in P1 geometry in comparison with P2 due to the larger charge transfer and orbital hybridization in the former geometry. Moreover, the band gap of the C₁₉Cr nanocage decreases after interaction with the nucleobases, and interestingly the impact is more pronounced for P1 geometry, confirming the higher sensitivity of C₁₉Cr to the nucleobases in P1 geometry. Our findings reveal the promising potential of C₁₉Cr as an organometallic carrier for nucleobases thymine and uracil.