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226 results on '"Khan, Asad Muhammad"'

30. A Pathway to Optimal Multivariate Synthesis of Fe2O3-CuO Bimetal Oxide Hybrid Nanoparticles: Transformation Through Mathematical Modelling.

Author

Sarfraz, Ambreen, Usman, Muhammad, Hussain, Nasira, Shafaat, Shanza, Khan, Asad Muhammad, Hussain, Zakir, Amin, Bilal Ahmad Zafar, and Shaikh, Ahson Jabbar

Abstract

Controlled and multivariate synthesis of Fe2O3-CuO bimetallic oxide nanoparticles is achieved by coprecipitation method with different concentrations of iron and copper oxide, followed by their optimization at specific pH, temperature, and time of addition of reagent. Concentration studies revealed changes in spectral band position to a hyperchromic shift with relevant increase in the concentration of CuO (100%). Hybrids with higher CuO concentration lead to hybrids with smaller size and higher stability. Temperature-dependent synthesis of bimetallic hybrid oxide nanoparticles showed an increase in size at higher temperatures, while at lower temperatures, stable oxide particles are observed. For pH-dependent synthesis, controlled size is observed at higher pH. Increasing the time of addition of reactant for optimized synthesis of bimetallic oxide nanoparticles showed a gradual decrease in size, hence better control. The results of size and zeta potential are transformed by the application of probability distribution function and grow-decay model. [ABSTRACT FROM AUTHOR]

Published
2024
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35. Understanding non-covalent interactions of graphene oxide toward transition metal surfaces and relation of binding constants with titration end points from dynamic light scattering studies.

Author

Ayoub, Muhammad Haris, Ahmad, Shehryar, Hassan, Zia Ul, Khan, Asad Muhammad, Bilal, Muhammad, Waseem, Amir, and Shaikh, Ahson Jabbar

Subjects
GRAPHENE oxide, BINDING constant, METALLIC surfaces, LIGHT scattering, VOLUMETRIC analysis, TRANSITION metals, TRANSITION metal oxides
Abstract

The understanding of non-covalent binding interactions of graphene oxide toward transition metal surfaces (Fe, Co, Ni, and Cu) was observed by ultraviolet–visible absorption spectroscopy, fluorescence emission spectroscopy, hydrodynamic size, and zeta potential studies through titration experiments. These interactions mainly occur through C=C double bonds of graphene oxide. Iron and cobalt nanoparticles interact strongly as compared to nickel and copper nanoparticles. The obtained Stern–Volmer plots are curved indicating that static and dynamic quenching occur simultaneously in these systems. The curves obtained for size titration graphs indicated the saturation end point for these titrations, which were then compared with binding constants obtained from linear Stern–Volmer plots. Interestingly, with lower binding constants, a higher concentration of nanoparticles was required for titration end points. These two complimentary techniques stood well quantitatively toward each other. Upon titrating the nanoparticles with graphene oxide, the zeta potential always lowered close to the value of graphene oxide, indicating that hybrids are more stable than the nanoparticles. [ABSTRACT FROM AUTHOR]

Published
2023
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37. Novel yellowish‐green single‐phased spinel Mg1−xBaxAl2O4:Mn2+ phosphor(s) for color rendering white‐light‐emitting diodes.

Author

Ain, Qurat Ul, Fazal, Tanzeela, Iqbal, Shahid, Mahmood, Sajid, Ismail, Bushra, Shah, Mazloom, Khan, Asad Muhammad, Bahadur, Ali, Alotaibi, Khalid M., and Alshalwi, Matar

Abstract

For white light‐rendering research activities, interpretation by using colored emitting materials is an alternative approach. But there are issues in designing the white color emitting materials. Particularly, differences in thermal and decay properties of discrete red, green, and blue emitting materials led to the quest for the search of a single‐phased material, able to emit primary colors for white light generation. The current study is an effort to design a simple, single‐phase, and cost‐effective material with the tunable emission of primary colors by a series of Mg1−xBaxAl2O4:Mn2+ nanopowders. Doping of manganese ion (Mn2+) in the presence of the larger barium cation (Ba2+) at tetrahedral‐sites of the spinel magnesium aluminate (MgAl2O4) structure led to the creation of antisite defects. Doped samples were found to have lower bandgaps compared with MgAl2O4, and hybridization of 3d‐orbitals of Mn2+ with O(2p), Mg(2s)/Al(2s3p) was found to be responsible for narrowing the bandgap. The distribution of cations at various sites at random results in a variety of electronic transitions between the valance band and oxygen vacancies as well as electron traps produced the antisite defects. The suggested compositions might be used in white light applications since they have three emission bands with centers at 516 nm (green), 464 nm (blue) and 622 nm (red) at an excitation wavelength of 380 nm. A detailed discussion to analyze the effects of the larger cationic radius of Ba2+ on the lattice strain, unit cell parameters, and cell volumes using X‐ray diffraction analysis is presented. [ABSTRACT FROM AUTHOR]

Published
2024
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49. Spectroscopic, conductivity and voltammetric investigations of interaction of sulfamethoxazole alone and in combination with trimethoprim with self-assembled structures.

Author

Asghar, Muhammad Nadeem, Bisma, Iqra, Sohail, Muhammad, Khan, Asad Muhammad, Rahman, Hafiz Muhammad Abd Ur, and Nadeem, Iram

Subjects
CRITICAL micelle concentration, SODIUM dodecyl sulfate, ANIONIC surfactants, TRIMETHOPRIM, CATIONIC surfactants, BIOLOGICAL membranes, SULFAMETHOXAZOLE
Abstract

The demand and urgency of new drug design and discovery is facing new challenges in the wake of spread and persistence of serious global threat of antibiotic resistance. One of the major hurdles in the development of new drugs that are more aqueous soluble and passively diffusible is the paucity of knowledge regarding their physicochemical interactions with biological membranes. Being chemical-mimics of biomembranes, surfactant-based micellar systems present excellent pseudo-membrane models to study biophysical interactions of drugs with biological membranes in vitro. The present research focuses on physicochemical interaction of sulfamethoxazole (SMZ) alone and in combination with trimethoprim (TMP) with cationic surfactant cetyltrimethylammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulfate (SDS). UV–visible spectroscopy, electrical conductivity and cyclic voltammetric techniques were employed to quantitate different drug-surfactant interaction parameters. UV–visible spectroscopic was used to evaluate critical micelle concentration (CMC) of CTAB and SDS in the presence of SMZ, TMP and their binary mixture in aqueous medium (pH 7.0). Differential absorption technique was used to determine partition coefficient (Kc) and binding constant (Kb) of SMZ and (SMZ + TMP) mixture with ionic micelles. Thermodynamic parameters of micellization such as Δ H m o , Δ S m o , and Δ G m o of CTAB and SDS in the presence SMZ and its mixed form with TMP were calculated in deionized water. Further, voltammetric investigations depict the strong binding of SMZ and its TMP mixture with CTAB micelles relative to SDS micelles. The effect of concentration of surfactant on the conductivities (κ) of sulphamethoxazole at different temperatures in deionized water; (a) SDS; (b) CTAB [ABSTRACT FROM AUTHOR]

Published
2023
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