Phytochemical analysis of the essential oil from botanically certified oleogum resin of Boswellia sacra (Omani Luban)

The yield of hydrodistillation of a botanically certified Oleogum Resin of Boswellia sacra essential oil (5.5%); and its chemical constituents were determined. The GC/MS technique was used for the analysis of the oil. Several oil components were identified based upon comparison of their mass spectral data with those of reference compounds published in literature or stored in a computer library. The oil was characterized by the high content of the monoterpenes (34) which constituted 97.3% in which E-beta-ocimene and limonene were the major constituents. The remaining 2.7% was accounted for the sesquiterpenes (16) in which the E-caryophyllene was the major constituent. The analysis proved the complete absence of the diterpenes.     

Surface enhanced Raman optical activity (SEROA)

Raman optical activity (ROA) directly monitors the stereochemistry of chiral molecules and is now an incisive probe of biomolecular structure. ROA spectra contain a wealth of information on tertiary folding, secondary structure and even the orientation of individual residues in proteins and nucleic acids. Extension of ROA to an even wider range of samples could be facilitated by coupling its structural sensitivity to the low-concentration sensitivity provided by plasmon resonance enhancement. This leads to the new technique of surface enhanced ROA, or SEROA, which is complementary to both SERS and ROA. In this tutorial review, we present a survey of theoretical and experimental work undertaken to develop SEROA and discuss these efforts in the context of the ROA technique, and, based on the authors' work, outline possible future directions of research for this novel chiroptical spectroscopy.     

Uniform in bandwidth consistency of the kernel-type estimator of the Shannon's entropy

We establish uniform-in-bandwidth consistency for kernel-type estimators of the differential entropy. Our proofs rely on the methods of Einmahl and Mason (2005) [10].     

Blow-up of Solutions of a Quasilinear Wave Equation with Nonlinear Dissipation

In this paper we establish the blow up of solutions to the quasilinear wave equation with a nonlinear dissipative term u_{tt} - M(||A^{1/2}u||²_2)Au + |ut|^βu_t = |u|^pu x ∈ Ω, t > 0     

Energy decay in a Timoshenko-type system of thermoelasticity of type III

In this paper we consider a one-dimensional linear thermoelastic system of Timoshenko type, where the heat conduction is given by Green and Naghdi theories. We prove the exponential stability by using the energy method.     

Density functional theory calculations of pentabromidooxomolybdate(V) anion with 2,2′-bipyridinium cation: Comparison between the calculated geometry and the crystal structure determination at 293 and 90 K

Mo^V ion complex in the [MoOBr₅]²⁻ anion is crystallized with 2,2′-bipyridinium dication. Mo^V is in a distorted octahedral environment at both 293 and 90 K, and is displaced from the plane of the four bromido ligands, with the Mo–Br_trans to the oxo ligand being significantly longer than the other equatorial bromido ligands. Extensive hydrogen bonding of the types (C,N)–H···(Br,O) and offset face-to-face interactions leading to a supramolecular crystal lattice that engineers the entrapment of [MoOBr₅]²⁻ anion. This is further stabilized by the Br···Br intermolecular interactions that hold the anionic network. The anisotropic cell contraction results in significant changes in nonbonding contacts. DFT calculations at the B3LYP level of theory using the pseudo potentials of “LANL2DZ” and “LANL2TZ (Mo)/6-31G*(C, N, Br, H)”, Slater Type Orbital (STO) and 3-21G basis sets were carried out. DFT calculations results from different basis sets were compared, and results show that the optimized calculated geometry is relatively consistent with the X-ray data and hence the observed structure for the complex is indeed possible. HOMO and LUMO orbitals and the energy gag were also determined.