Terbium sensitized luminescence for the determination of fexofenadine in pharmaceutical formulations

A sensitive and specific luminescence method for the determination of Fexofenadine (FEX), in pharmaceutical formulations is reported. The method is based on the sensitization of terbium (Tb³⁺) by complex formation with FEX. The luminescence signal for Tb–FEX complex is greatly enhanced by the addition of triethylamine (ET₃N) and zinc nitrate in methanol solution. Monitoring of the signal is accomplished when the instrument is in the phosphorescence mode with the excitation and emission wavelengths set at λ_ex = 220 nm and λ_em = 550 nm respectively. Optimum conditions for the formation of the complex in methanol were 2.25 × 10^?6 M of Tb³⁺, 5.00 × 10^?6 M of Et₃N and Zn²⁺ which allows for the determination of 10–800 ppb of FEX in the batch mode with a detection limit of 0.3 ppb. The proposed method was successfully applied for the determination of FEX in pharmaceutical formulations.     

Deciphering the Spectral Tuning Mechanism in Proteorhodopsin: The Dominant Role of Electrostatics Instead of Chromophore Geometry

Proteorhodopsin (PR) is a photoactive proton pump found in marine bacteria. There are two phenotypes of PR exhibiting an environmental adaptation to the ocean's depth which tunes their maximum absorption: blue-absorbing proteorhodopsin (BPR) and green-absorbing proteorhodopsin (GPR). This blue/green color-shift is controlled by a glutamine to leucine substitution at position 105 which accounts for a 20 nm shift. Typically, spectral tuning in rhodopsins is rationalized by the external point charge model but the Q105L mutation is charge neutral. To study this tuning mechanism, we employed the hybrid QM/MM method with sampling from molecular dynamics. Our results reveal that the positive partial charge of glutamine near the C₁₄−C₁₅ bond of retinal shortens the effective conjugation length of the chromophore compared to the leucine residue. The derived mechanism can be applied to explain the color regulation in other retinal proteins and can serve as a guideline for rational design of spectral shifts.     

Bridged Aromatic Oxo- and Thioethers with Intense Emission in Solution and the Solid State

In this contribution, we report on a class of emitters based on bridged oxo- and/or thioethers revealing striking photoluminescence properties in fluid solution and in the solid state. In total, nine compounds were investigated concerning their photophysical properties, which were interpreted by quantum chemical calculations. To our delight, we discovered compounds possessing nearly identical photoluminescence quantum yields (Φ_F) in solution and in the solid state, which has been rarely reported so far. Besides these efforts, we shed light on the influence of polymorphism and solvent polarity on the emission properties. In addition, an in-depth X-ray diffractometric analysis was conducted to correlate molecular packing in the crystal with differences in the photophysical properties.     

Solving System of Conformable Fractional Differential Equations by Conformable Double Laplace Decomposition Method

Herein, an approach known as conformable double Laplace decomposition method (CDLDM) is suggested for solving system of non-linear conformable fractional differential equations. The devised scheme is the combination of the conformable double Laplace transform method (CDLTM) and, the Adomian decomposition method (ADM). Obtained results from mathematical experiments are in full agreement with the results obtained by other methods. Furthermore, according to the results obtained we can conclude that the proposed method is efficient, reliable and easy to be implemented on related many problems in real-life science and engineering.     

Sulfated Triterpenes from Lemon Balm

The hydroalcoholic (EtOH/H₂O) extract of matured leaf margins of lemon balm (Melissa officinalis L.) afforded a new 3,23‐disulfate of 2α,3β‐23,29‐tetrahydroxyolean‐12‐en‐28‐oic acid 28‐O‐β‐D ‐glucopyranoside ( 1 ) and a new 23‐monosulfate of 2α,23‐dihydroxyurs‐12‐en‐28‐oic acid 3‐O‐β‐D ‐glucopyranoside ( 2 ), along with six known compounds, i.e., 23‐monosulfate of 2α,3β,19α,23‐tetrahydroxyurs‐12‐ene‐28‐oic acid 28‐O‐β‐D ‐glucopyranoside ( 3 ), 3,5,6‐trihydroxydehydro‐α‐ionol 9‐O‐β‐D ‐glucopyranoside ( 4 ), quadranoside III ( 5 ), rosmarinic acid ( 6 ), caffeic acid ( 7 ), and luteolin ( 8 ). All the isolated compounds were evaluated for their antioxidant, antimicrobial, antimalarial, and cytotoxic activities. Only rosmarinic acid exhibited substantial antioxidant and antimicrobial activities, whereas sulfated terpenes showed considerably lower or no antimicrobial activity.     

Solving Hankel matrix approximation problem using semidefinite programming

Positive semidefinite Hankel matrices arise in many important applications. Some of their properties may be lost due to rounding or truncation errors incurred during evaluation. The problem is to find the nearest matrix to a given matrix to retrieve these properties. The problem is converted into a semidefinite programming problem as well as a problem comprising a semidefined program and second-order cone problem. The duality and optimality conditions are obtained and the primal–dual algorithm is outlined. Explicit expressions for a diagonal preconditioned and crossover criteria have been presented. Computational results are presented. A possibility for further improvement is indicated.     

Hybrid Methods for Approximating Hankel Matrix

Hybrid methods for minimizing least distance functions with Hankel positive semi-definite matrix constraints are considered. Our approach is based on (i) a projection algorithm which converges globally but slowly; and (ii) the Newton method which is faster. Hybrid methods that attempt to combine the best features of both methods are then considered. Comparative numerical results are reported.     

Fabrication of inorganic alumina particles at nanoscale by a pulsed laser ablation technique in liquid and exploring their protein binding,anticancer and antipathogenic activities

The interaction of nanoparticles with biological systems can provide useful information about their therapeutic applications. The aluminum nanoparticles (Al₂O₃ NPs) were synthesized by laser ablation technique and well-characterized by different methods. Fluorescence spectroscopy, circular dichroism (CD) spectroscopy, and molecular docking studies were employed to evaluate the effect of Al₂O₃ NPs on the protein structure. Growth inhibitory and apoptotic effects of the Al₂O₃ NPs against K562 cancer cells and lymphocyte cells were assessed using [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT), flow cytometry, and real time polymerase chain reaction (PCR) assays. The antipathogenic activity of Al₂O₃ NPs against a diverse range of Gram-negative and Gram-positive pathogens was explored through a disk diffusion method. The characterization techniques determined that the Al₂O₃ NPs were successfully synthesized in the nanoscales. Intrinsic, 1-anilino-8-naphthalenesulfonate (ANS) and acrylamide fluorescence spectroscopy studies disclosed that Al₂O₃ NPs can partially change the tertiary structure of human serum albumin (HSA), whereas CD spectroscopy investigation depicted that the secondary structure of HSA remained intact. Molecular docking investigation also manifest that the Al₂O₃ nano-clusters preferably bind to electrostatic residues. Al₂O₃ NPs exhibited promising and selective anticancer features through reactive oxygen species (ROS) production, apoptosis induction, and elevation of Bax/Bcl-2 mRNA ratio. Furthermore, the Al₂O₃ NP showed a remarkable antibacterial activity against both Gram-negative and Gram-positive pathogens. In conclusion, it may be suggested that the synthesized Al₂O₃ NPs can be integrated in the development of anticancer and antipathogenic agents.     

Weak sharp solutions for generalized variational inequalities

We consider weak sharp solutions for the generalized variational inequality problem, in which the underlying mapping is set-valued, and not necessarily monotone. We extend the concept of weak sharpness to this more general framework, and establish some of its characterizations. We establish connections between weak sharpness and (1) gap functions for variational inequalities, and (2) global error bound. When the solution set is weak sharp, we prove finite convergence of the sequence generated by an arbitrary algorithm, for the monotone set-valued case, as well as for the case in which the underlying set-valued map is either Lipschitz continuous in the set-valued sense, for infinite dimensional spaces, or inner-semicontinuous when the space is finite dimensional.