Adsorption of free radical TEMPO onto Al2O3 nanoparticles and evaluation of radical scavenging activity.

This study describes the adsorption of free radical TEMPO onto Al2O3 nanoparticles in the solvents with different polarities including DMF, methanol, acetone, THF, petroleum ether and n-hexane at ambient temperature to evaluate the radical scavenging activity. The adsorption percentage of radical is calculated by measuring the maximum adsorption intensity of the ultraviolet (UV) absorption spectrum of TEMPO in the presence and the absence of Al2O3 nanoparticles. The morphology of Al2O3 nanoparticles before and after adsorption of TEMPO is studied using transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform infrared (FT-IR) spectroscopy. The adsorption energy and other thermochemical data for the adsorption of TEMPO over different active sites of Al2O3 are estimated via dispersion corrected density functional theory (DFT + Disp). The donor-acceptor interactions between Al2O3 and TEMPO are calculated using natural bond orbital (NBO) theory. It is found that Al2O3 nanoparticles have efficient radical scavenging activity (RSA) in the range of 50-72%. Approximately, a linear relationship between dielectric constant of solvent and the absorption percentage of TEMPO over Al2O3 nanoparticles is achieved. So that with decreasing the polarity of solvent, the adsorption of TEMPO onto Al2O3 nanoparticles is increased. The adsorption of TEMPO over Lewis acidic sites of Al2O3 is more favored than Brønsted acidic and basic sites. The comparison between experimental and calculated IR spectra of TEMPO/Al2O3 complexes provides the good evidence for the adsorption of TEMPO onto the surface of Al2O3 nanoparticles.

Ultrafast tunable integrated Faraday isolator based on optical pumping in a graphene-InSb-graphene structure.

We have designed a new class of single-stage Faraday isolators that employs two sheets of graphene. Using nonreciprocal optical materials such as InSb boosts plasmonic coupling between the graphene layers, which leads to a 45 deg polarization rotation as well as increased transmission through the structure. More than 91% transmission is achieved in the THz band (1 THz-7 THz). This design opens up the way in ultrafast integrated magneto-optical nanophotonic devices to realize single-stage isolators with enhanced transmittance in the THz band.

Wide-angle giant transverse magneto-optical Kerr effect in a gyromagnetic superlens.

In this Letter, we report a gyromagnetic superlens showing giant transverse magneto-optical Kerr effect (TMOKE) in a wide-range of incident angles. The existence of loss is the heart of TMOKE, and we found that the wide-angle giant TMOKE occurs when this loss takes place due to permittivity, while the gyration parameter is the result of permeability. Thus, the permeability of the mentioned gyromagnetic slab is tensor, and it only responds to s-polarized light.

Scavenging performance and antioxidant activity of γ-alumina nanoparticles towards DPPH free radical: Spectroscopic and DFT-D studies.

The radical scavenging performance and antioxidant activity of γ-alumina nanoparticles towards 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical were investigated by spectroscopic and computational methods. The radical scavenging ability of γ-alumina nanoparticles in the media with different polarity (i.e. i-propanol and n-hexane) was evaluated by measuring the DPPH absorbance in UV-Vis absorption spectra. The structure and morphology of γ-alumina nanoparticles before and after adsorption of DPPH were studied using XRD, FT-IR and UV-Vis spectroscopic techniques. The adsorption of DPPH free radical on the clean and hydrated γ-alumina (1 1 0) surface was examined by dispersion corrected density functional theory (DFT-D) and natural bond orbital (NBO) calculations. Also, time-dependent density functional theory (TD-DFT) was used to predict the absorption spectra. The adsorption was occurred through the interaction of radical nitrogen N and NO2 groups of DPPH with the acidic and basic sites of γ-alumina surface. The high potential for the adsorption of DPPH radical on γ-alumina nanoparticles was investigated. Interaction of DPPH with Brønsted and Lewis acidic sites of γ-alumina was more favored than Brønsted basic sites. The following order for the adsorption of DPPH over the different active sites of γ-alumina was predicted: Brønsted base < Lewis acid < Brønsted acid. These results are of great significance for the environmental application of γ-alumina nanoparticles in order to remove free radicals.

Generalization of transfer matrix method for bi-gyrotropic double-negative magnetic materials in order to use them in multilayer structures.

The optical and magneto-optical (MO) response in magnetic multilayer systems is calculated by the transfer matrix method (TMM). In a bi-gyrotropic medium, the electric permittivity (ϵ) and the magnetic permeability (µ) coefficients are in the form of non-diagonal tensors synchronously, in which their non-diagonal elements refer to the existence of anisotropy in such a medium. On the other hand, in a double-negative medium, both the ϵ and µ coefficients are negative. In the present study, we have investigated the combination of these two phenomena and have introduced a TMM-based approach for studying the optical and MO properties of multilayer structures containing bi-gyrotropic double-negative magnetic materials (BDNMMs), whose diagonal and non-diagonal elements refer to the existence of negativity and anisotropy, respectively. We have also investigated the capability of such BDNMM materials in comparison with conventional bi-gyrotropic materials in magneto-photonic crystal structures. As a result, we found that broadening occurs in the optical and magneto-optical responses simultaneously.

Epstein-Barr Virus-Positive Diffuse Large B-Cell Lymphoma: Is It Different between Over and Under 50 Years of Age?

BACKGROUND: Epstein-Barr virus (EBV) positive diffuse large B-cell lymphoma (DLBCL) of the elderly is an entity introduced in the latest WHO classification of lymphoid tumors and defined in patients older than 50 years without prior lymphoma or immunodeficiency. However, recently it has also been seen in patients under 50. There is thus debate as to whether these are separate entities. MATERIALS AND METHODS: In this retrospective study, we analyzed de novo DLBCL admitted to our institute over a period of two years. Clinical data included age, sex, nodal and extranodal presentation. The results of an immunohistochemistry (IHC) panel were also reviewed. IHC findings were mainly used to sub-classify DLBCL as germinal center vs. non germinal center types. IHC for identification of LMP-1 (latent membrane protein) and in situ hybridization for detection of EBV- encoded RNA (EBER) was performed. EBV prevalence, clinical data and IHC findings were compared between patients under and over 50 years of age. RESULTS: Out of 95 DLBCL, 11.6% were EBV positive (7.5% and 14.5% in the young and old groups). We did not find any significant differences in IHC subclasses and clinical data between EBV positive DLBCL (EBV+DLBCL) of young and old groups. CONCLUSIONS: EBV+DLBCL are not exclusive to patients older than 50 years. With regard to clinical data as well as IHC subclasses, no differences were evident between EBV+DLBCL of young and old groups. Our suggestion is to eliminate any cut off age for EBV+DLBCL.

Stereochemistry and spectroscopic analysis of bis-Betti base derivatives of 2,3-dihydroxynaphthalene.

Density functional theory (DFT) was used to study the stereochemistry, thermodynamic stability, and spectra of recently synthesized bis-Betti base derivatives of 2,3-dihydroxynaphthalene obtained through multicomponent reactions of 2,3-dihydroxynaphthalene with aminoisoxazole and benzaldehyde derivatives. The stereochemistry of the products was investigated by theoretically calculating the infrared (IR) and proton nuclear magnetic resonance ((1)H NMR) spectra of the diastereomers and comparing them to the corresponding experimental data. The thermochemical properties of the reactions, including the enthalpy, internal energy, entropy, and Gibbs free energy, were also calculated. The diastereoselectivity of the reactions was estimated from the equilibrium distribution of diastereomers. According to the results, the synthesis of bis-Betti bases is exothermic and accompanied by a decrease in entropy. The energy difference between the diastereomers is quite small, but the Gibbs free energy change for the equilibrium syn <−> anti favors the anti over syn configuration. These results are in good agreement with experimental observations.

Adjustable magneto-optical isolators with flat-top responses.

In order to construct flat-top magneto-optical isolators (MOIs), we have performed a theoretical study on the case of transmission-type one-dimensional magnetophotonic crystals (MPCs). We have introduced high performance MPC structures with flat-top responses and with the capability of adjusting to perfect MOIs. The adjustment is carried out by tuning the applied magnetic field. All introduced MOIs are sufficiently thin with acceptable transmission bandwidth. In the best case, we have achieved a 19.42 µm-thick perfect MOI with the flat-top width of 7.2 nm. For practical purposes, we have also considered the influence of the error in thickness of individual layers on the operational parameters of the MOIs and investigated the possibility of compensating the deviations by the magnetic adjustment.

Influence of thickness error on the operation of adjustable magneto-optical isolators.

We have performed a theoretical study on the case of transmission-type one-dimensional magnetophotonic crystals (MPCs) to establish a practical magneto-optical isolator (MOI) that operates properly even in the presence of construction errors. We have introduced a very thin MPC structure with high transmittance and a large Faraday rotation, with the capability of adjusting to a perfect MOI. A minor thickness error for the individual layers of this MOI may take it from being a perfect MOI; however, its adjustability can provide a stable operation against fabrication errors.