Wyniki wyszukiwania - BazTech

1

The study of structural, elastic, electronic and optical properties of CsYx I(1 − x)(Y = F, Cl, Br) using density functional theory

Mian S. A., Muzammil M., Rahman G., Ahmed E.

Materials Science Poland

|

2017

|

Vol. 35, No. 1

197--210

EN

The structural, electronic, elastic and optical properties of CsYx I(1 − x)(Y = F, Cl, Br) are investigated using full potential linearized augmented plane wave (FP-LAPW) method within the generalized gradient approximation (GGA). The ground state properties such as lattice constant (ao) and bulk modulus (K) have been calculated. The mechanical properties including Poisson’s ratio (σ), Young’s modulus (E), anisotropy factor (A) and shear modulus (G) were also calculated. The results of these calculations are comparable with the reported experimental and theoretical values. The ductility of CsYx I(1 − x) was analyzed using Pugh’s rule (B/G ratio) and Cauchy’s pressure (C12−C44). Our results revealed that CsF is the most ductile among the CsYx I(1 − x) (Y = F, Cl, Br) compounds. The incremental addition of lighter halogens (Yx) slightly weakens the strength of ionic bond in CsYx I(1 − x). Moreover, the optical transitions were found to be direct for binary and ternary CsYx I(1 − x). We hope that this study will be helpful in designing binary and ternary Cs halides for optoelectronic applications.

2

Poly(N-isopropylacrylamide-co-methacrylic acid) microgel stabilized copper nanoparticles for catalytic reduction of nitrobenzene

Farooqi Z. H., Butt Z., Begum R., Khan S. R., Sharif A., Ahmed E.

Materials Science Poland

|

2015

|

Vol. 33, No. 3

627--634

EN

Pakistan Poly(N-isopropylacrylamide-co-methacrylic acid) microgels [p(NIPAM-co-MAAc)] were synthesized by precipitation polymerization of N-isopropylacrylamide and methacrylic acid in aqueous medium. These microgels were characterized by dynamic light scattering and Fourier transform infrared spectroscopy. These microgels were used as micro-reactors for in situ synthesis of copper nanoparticles using sodium borohydride (NaBH4) as reducing agent. The hybrid microgels were used as catalysts for the reduction of nitrobenzene in aqueous media. The reaction was performed with different concentrations of catalyst and reducing agent. A linear relationship was found between apparent rate constant (kapp) and amount of catalyst. When the amount of catalyst was increased from 0.13 to 0.76 mg/mL then kapp was increased from 0.03 to 0.14 min−1. Activation parameters were also determined by performing reaction at two different temperatures. The catalytic process has been discussed in terms of energy of activation, enthalpy of activation and entropy of activation. The synthesized particles were found to be stable even after 14 weeks and showed catalytic activity for the reduction of nitrobenzene.

3

Recursterols A and B, Chymotrypsin Inhibiting Sterols from Haloxylon recurvum

Hussain S., Ahmed E., Malik A., Ferheen S., Jabbar A., Ashraf M., Lodhi M., Choudhary M.

Polish Journal of Chemistry

|

2006

|

Vol. 80, nr 3

409-415

EN

Recursterols A(1) and B (2), the new C-24 alkylated sterols, have been isolated from the chloroform-soluble fraction of Haloxylon recurvum. Their structures have been deduced through spectroscopic techniques including 2D NMR. Both 1 and 2 showed promising inhibitory potential against the enzyme chymotrypsin.

4

Lipoxygenase Inhibiting Steroidal Glycosides and Naphthene Derivatives from Haloxylon salicornicum

Ferheen S., Ahmed E., Afza N., Malik A., Nawaz S., Choudhary M.

Polish Journal of Chemistry

|

2005

|

Vol. 79 / nr 9

1469-1476

EN

Allostigmasterol glycosides 1 and 2 and monocyclic naphthene derivatives 3 and 4 have been isolated from methanolic extract of Haloxylon salicornicum and their structures elucidated through spectroscopy. Triacontanoic acid 5, ergosterol peroxide 6 and lupeol 7 were also obtained for the first time from this species. Both 1 and 2 showed moderate lipoxygenase inhibiting activity.