S. Muhammad

Ex Vivo Assessment of Carbon Tetrachloride (CCl 4 )-Induced Chronic Injury Using Polarized Light Spectroscopy

The liver performs various functions, such as the production and detoxification of chemicals; therefore, it is susceptible to hepatotoxins such as carbon tetrachloride (CCl4), which causes chronic injury. Thus, assessment of injury and its status of severity are of prime importance. Current work reports an ex vivo study for probing the severance of hepatic injury induced by CCl4 with polarized light over the spectral range 400–800 nm. Different concentrations of CCl4 were used to induce varying severity of hepatic injury in a rat model. Linear retardance, depolarization rates, and diagonal Mueller matrix elements (m22, m33, and m44), were successfully used as the distinguishing criterion for normal and different liver injuries. Our results show that linear retardance for injured liver samples with lower doses of CCl4 tends to increase when compared with normal liver samples, while samples injured at higher doses of CCl4 offer almost no retardance. Total, linear, and circular depolarizations follow decreasing trends with increased liver injury severity over the entire investigated wavelength range. Linear polarization states were observed to be better maintained as compared to circular polarization states for all samples. Furthermore, numerical values of diagonal elements of the experimentally measured Mueller matrix also increase with increasing doses of CCl4. Liver fibroses, change in transport albedo, and the relative refractive index of the extracellular matrix caused by CCl4 are responsible for the observed differences. These results will provide a pathway to gauge the severity of injury caused by toxic chemicals.

Electronic Band Structure and Optical Response of Spinel SnX2O4 (X = Mg, Zn) through Modified Becke-Johnson Potential *

The modified Becke—Johnson exchange potential approximation is applied to predict the band structure, optical parameters and electron density of SnMg2O4 and SnZn2O4. The local density approximation, generalized gradient approximation (GGA), EV-GGA significantly underestimate the direct band gap values compared to modified Becke—Johnson approximation. The band gap dependent optical parameters such as dielectric constant, index of refraction, reflectivity, and optical conductivity are calculated and analyzed. A prominent feature of cation replacement is observed and analyzed for these studied compounds. The replacement of the cation Mg by Zn leads to a significant reduction in the value of band gap and consequently affects its dependant optical parameters. This variation is of crucial importance for device fabrication in different regions of the spectrum.

Electronic and Optic Properties of Cubic Spinel CdX2O4 (X=In, Ga, Al) through Modified Becke?Johnson Potential

A new potential approximation known as modified Becke?Johnson based on density functional theory is applied to compute the electronic band profile and optical response of CdIn2O4, CdGa2O4 and CdAl2O4 compounds. The direct band gap with common LDA, GGA and EV-GGA is drastically underestimated compared with modified Becke?Johnson approximation, whose results are significantly closer to the experimental findings. The optical properties like dielectric constant, refractive index, reflectivity, optical conductivity and absorption coefficient are also computed. A unique characteristic associated with cation replacement is studied; the replacement of cation In by Ga and Ga by Al significantly reduces the direct energy band gap in these compounds. This variation is of crucial importance for band gap dependent optical properties of these compounds, which is also proof for applications of these compounds in optoelectronic devices.

Electronic Band Profile and Optical Response of Spinel MgIn2O4 through Modified Becke—Johnson Potential

We employ the first-principles technique based on the modified Becke—Johnson (BJ) exchange potential for the prediction of the electronic band structure, optical properties, and electron density of the cubic MgIn2O4 spinel compound. It is found that the calculated band gap value with the modified BJ approximation is significantly improved over the results based on the generalized gradient approximation and the local density approximation in comparison to the experimental data. The band gap dependent optical parameters such as the dielectric constant, refractive index, reflectivity, optical conductivity, and electron density are predicted. The optical response suggests that MgIn2O4 is an applicant material in optoelectronic devices in various parts of the energy spectrum like MgAl2O4 and MgGa2O4.

Electronic and Optical Properties of Spinel GeMg2O4 and GeCd2O4

Oxide spinels have potential applications in optoelectronics and optics fields. In this work the electronic band structure and optical properties of GeMg2O4 and GeCd2O4 are calculated by first principles technique based on the new potential approximation known as the modified Becke–Johnson exchange potential approximation (mBJ). The local density and generalized gradient approximations significantly underestimate the direct band gap values compared to the mBJ. The band gap dependent optical parameters such as dielectric constant, refractive index, reflectivity and optical conductivity are calculated and analyzed. The replacement of the cation is observed and analyzed for the compounds studied and a prominent change is noticed. The replacement of the cation Mg by Cd reduces the band gap and its dependent optical parameters. For device fabrication in different regions of the spectrum this variation is strongly recommended.

Effective phthalocyanines mediated photodynamic therapy with doxorubicin or methotrexate combination therapy at sub-micromolar concentrations in vitro

To improve a cancer patients quality of life, short treatment duration resulting in rapid tumour removal while sparing normal tissue are highly desirable. Photodynamic therapy (PDT) commonly applied in a single treatment, while often effective can be limited at low photosensitizer or light doses. Combination therapies can overcome the efficacy limitations while not increasing treatment-associated morbidity. Here the efficacy of combination therapy comprised of doxorubicin (DOX) or methotrexate (MTX) with Photosens mediated PDT was investigated in three cell lines in vitro, employing multiple incubation sequences. Photosense is a mixture of aluminium phthalocyanines with different sulfonation. The results demonstrated higher synergistic effects when DOX or MTX-mediated chemotherapy preceded PDT light activation by 24 h. MTX is marginally more cytotoxic than DOX, when combined with Photosens (AlPcS2-4) mediated PDT. While MTX and DOX exposure prior to AlPcS2-4 incubation may enhance mitochondrial localisation photosensitizer, the simultaneous targeting of DNA, proteins, and lipids of the combination therapies leads to the observed high cytotoxicity at sub μM drug doses.

Optoelectronic and Magnetic Properties of Eu2Si5N8: An Ab-initio Study

Abstract Eu2Si5N8 is considered the most important compound in the development of inorganic materials with high potential and performance. Therefore, the electronic, magnetic and optical properties of Eu2Si5N8 are investigated here using density functional theory. The electronic interactions are described within the generalised gradient approximation, GGA+U (where U is the Hubbard Coulomb energy term). The calculated energy gap was 3.5 eV for the investigated compound, resulting in a direct band gap semiconductor. The optical constants, including the dielectric function, refractive index, absorption coefficient, reflectivity, and energy loss function were calculated for radiation up to 14 eV. The optical properties demonstrate that the main differences in absorption, reflectivity, energy-loss function and refractive index occur in the infrared and visible regions for the spin-up and spin-down states, which makes this material an excellent candidate for optical memory devices.