RESUMO
In this work, we have conducted an ab initio computational research of the pressure impact on the structural, elastic, thermodynamic, electronic, and optical properties of Be-based fluoroperovskite XBeF3 (X= K, Rb) compounds by using GGA+ PBEsol functional based on DFT in the CASTEP Package. These compounds' ground state characteristics were examined, including the lattice parameters, coefficient compressibility (B), and its pressure derivative(B'). Structural characterization shows that these compounds keep a cubic crystal structure with the impact of stress till 18 GPa. In addition, we computed elastic constants, Young's modulus (E), shear modulus (G), Poisson's ratio (σ), and the anisotropy factor (A). As the elastic stiffness parameters comply with the Born stability criterion, the examined phases are mechanically stable. The ductility of phases XBeF3 (X= K, Rb) has been assured from the high coefficient compressibility (B) and Pugh's ratio values. Furthermore, we determined the thermodynamic behavior of XBeF3 (X= K, Rb) through the quasi-harmonic Debye model. The electronic band structure and DOS (Density of States) were studied, which provide information on the insulator properties of the two compounds. Also, we studied various optical properties of the materials including: refractive index, optical reflectivity, coefficient of absorption, both real and imaginary parts of dielectric function and lastly the energy loss function. On the basis of these reported studies of these materials, their applications in many modern electronic devices can be predicted.
RESUMO
Acne vulgaris is a common global skin disease affecting teenagers and adults and exerting serious psychological impacts which includes everlasting scarring, reduced self-image, depression and anxiety. One of the suspected causative agent of acne is Propionibacterium acnes; a Gram positive anaerobic organism which lives in skin hair follicle and openings. Treatments currently available for acne include use of oral antibiotics, hormones, isotretinoin and also physical treatments like lesion removal and photo-therapy. All these are associated with risks and none is completely satisfactory.Therefore, natural alternatives are gaining greater research support but lacks sufficient studies. In our study we have isolated Propionibacterium acnes from infected individuals and tested the effect of certain chemicals and herbs/ vegetable extracts against it. There anti-acne property was studied and compared with commercially used antibiotics including Clinagel (Clindamycin phosphate), Vibramycin (Doxycycline), Erythromycin, Novidat (Ciprofloxacin) and Amoxil (Amoxicillin). Results indicate that some of the selected herbs and chemicals showed good activity against Propionibacterium acnes synergistic to the antibiotics when used alone or in combination. Findings of this research can play an important role in natural product based drug discovery for the treatment of Acne vulgaris.