Spectral and molecular docking studies of nucleic acids/protein binding interactions of a novel organometallic palladium (II) complex containing bioactive PTA ligands: Its synthesis,anticancer effects and encapsulation in albumin nanoparticles

The organometallic palladium complex with nitrogen-containing heterocycles is a potent antitumor agent. Coordination of phosphorus ligands to organometallic complexes increases their hydrophilicity, promotes ligand−DNA interactions and damage level to cancer cells, and blocks division in target cells. In this study, a phosphaadamantane palladium complex ([Pd{(C,N)- (C₁₂H₈NH₂)} (PTA) Cl], PTA = 1,3,5-Triaza-7-phosphaadamantane) ( 2 ) was synthesized via the reaction of biologically active PTA with binuclear palladacycles [Pd₂{(C,N)-(C₁₂H₈NH₂)}₂(μ-Cl)₂] ( 1 ). In vitro studies of the complex with DNA (calf-thymus) explored by UV–Vis, emission titration, circular dichroism and helix melting methods showed that the complex interacts with DNA via an intercalative mechanism. Furthermore, competitive binding studies using warfarin, digoxin and ibuprofen site markers containing definite binding sites revealed the binding of the complex to site I on bovine serum albumin. The in vitro release mechanism of the palladium complex exhibited a biphasic pattern characterized by an initial burst release followed by a slower sustained release. Ultimately, in vitro evaluation of cytotoxicity and cell death showed that the complexes were able to decrease the viability of human cancer cell lines (MCF-7 and Jurkat) in a dose-dependent manner, but lower decreases were observed in the viability of normal fibroblast cells ASF-4 at the dosages evaluated. Finally, the order of in vitro anticancer activities was found to be consistent with the DNA-binding affinities.     

Investigation of the quantum dot infrared photodetectors dark current

Quantum dot infrared photodetectors (QDIPs) are more efficient than other types of semiconductor based photodetectors; so it has become an actively developed field of research. In this paper quantum dot infrared photodetector dark current is evaluated theoretically. This evaluation is based on the model that was developed by Ryzhii et al. Here it is assumed that both thermionic emission and field-assisted tunneling mechanisms determine the dark current of QDIPs; moreover we have considered Richardson effect, which has not been taken into account in previous research. Then a new formula for estimating average number of electrons in a quantum dot infrared photodetector is derived. Considering the Richardson effect and field-assisted tunneling mechanisms in the dark current improves the accuracy of algorithm and causes the theoretical data to fit better in the experiment. The QDIPs dark current temperature and biasing voltage dependency, contribution of thermionic emission and field-assisted tunneling at various temperatures and biasing voltage in the QDIPs dark current are investigated. Moreover, the other parameter effects like quantum dot (QD) density and QD size effect on the QDIPs dark current are investigated.     

Gravitational Spin Entropy Production

Spin entropy production for particles with arbitrary spin moving in a curved spacetime is discussed. There is a Wigner rotation due to both the acceleration an the curvature, which causes an initial pure state to transform into a final mixed state. Depending on the spacetime characteristics, one may find paths on which there is no Wigner rotation and the state remains pure.     

Optimization and characterization of electrospun chitosan/poly(vinyl alcohol) nanofibers as a phenol adsorbent via response surface methodology

Fabrication and characterization of chitosan/poly(vinyl alcohol) electrospun nanofibers for adsorption of phenol from water were investigated. The effects of voltage (15–30 kV), solution injection flow rate (0.5–1.5 ml/hr), distance of needle and collector (10–20 cm) and chitosan/poly(vinyl alcohol) ratio (25/75, 50/50, 75/25) were studied to obtain the optimum electrospinning conditions for the maximum adsorption capacity of phenol. Central composite design (CCD) was used to investigate and optimize the processing factors for production of chitosan/poly(vinyl alcohol) nanofibers from aqueous solutions. The nanofibers were characterized using scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR). Uniform beadless nanofibers with the minimum diameters of 3–11 nm were obtained at chitosan/poly(vinyl alcohol) ratio of 50/50, voltage of 22.5 kV, distance of 15 cm and injection flow rate of 1.99 ml hr^?1. Fourier transform infrared spectrum of chitosan/poly(vinyl alcohol) exhibited the existence of relevant functional groups of both poly(vinyl alcohol) and chitosan in the blends. Results of CCD show that among all processing factors, rate of electrospinning will highly affect the nanofiber adsorption. The response surface quadratic order model presented correlation coefficient explaining 69.5% of the variability in the adsorption. Copyright © 2017 John Wiley & Sons, Ltd.     

A numerical approach for analyzing quantum dot infrared photodetectors' parameters

Quantum dot infrared photodetectors (QDIPs) have many advantages over other types of semiconductor-based photodetectors. However some of its characteristics have been investigated theoretically, there are many unstudied points. In this paper a new approach is presented to evaluate quantum dot infrared photodetectors dark current and photocurrent. In this study, it is assumed that both thermionic emission and field-assisted tunneling mechanisms determine the dark current of quantum dot detectors. Based on these assumptions, new formula for average number of electron in a quantum dot for both, dark and illumination condition is calculated, which is more accurate than the previous reported formulas; because in deriving previous reported formulas, it was assumed only thermionic emission determines dark current but field-assisted tunneling mechanisms has not been considered. Then numerical method is used to calculate the average number of electron in a quantum dot and to determine dark current and photocurrent. The theoretical results are compared with experimental data. They have good agreement with available experimental data.     

Scaled‐up,selective and green synthesis of sulfoxides under mild conditions using (CeIII‐MoVI)Ox/aniline hybrid rods as an efficient catalyst

A novel hybrid material, (Ce^III‐Mo^VI)O_x/aniline, with rod‐like morphology is synthesized through a wet chemical method using Mo₃O₁₀(C₆H₅NH₃)₂.2H₂O nanowires as precursor. The synthesized materials are characterized by XRD, XPS, SEM, TEM, FTIR, Raman, UV–Vis, TGA, and elemental analysis. Also, their catalytic activities as a hybrid catalyst are tested in the selective oxidation of sulfides using hydrogen peroxide as a green oxidant. The proposed novel hybrid catalyst shows an excellent performance under green conditions at mild temperature. Furthermore, the scalability of the oxidation reaction is shown by making multi‐gram quantities at optimized conditions.     

Theoretical study on alkaloid encapsulating via cyclopentano-cucurbit[n]uril (n = 8, 10)/graphene oxide heterojunction

Here, physical chemistry properties of the inclusion complexes of some alkaloids and cyclopentano-cucurbit[8, 10]urils (Cy-CB[8, 10]) were investigated via molecular dynamic (MD) simulations and density functional theory (DFT) calculations. The possibility of the heterojunction formation between cyclopentano-cucurbit[8, 10]urils and graphene oxide was investigated via MD simulation. Based on the results, an effective role of graphene oxide on the encapsulation complex formation, especially in the presence of codeine and morphine was confirmed. DFT (M06-2X) and DFT-D3 (M06-2X-D3) functionals were applied for geometry optimization of the complexes. To have an insight into the atomic level, different analyses, such as natural bond orbital and quantum theory of atoms in molecule analyses were applied and discussed. DFT results confirm that Cy-CB[8] makes a stronger interaction with alkaloids in comparison with Cy-CB[10]. Thermodynamic studies show that the complexation process of codeine inside Cy-CB[n] is more favorable than other complexes. Moreover, energy analysis showed that the van der Walls part plays an important role in alkaloid stabilization inside the Cy-CB[n] cavity.     

A high-throughput screening assay for assessing the viability of Cryptococcus neoformans under nutrient starvation conditions

Cryptococcus neoformans causes an estimated 600,000 AIDS-related deaths annually that occur primarily in resource-limited countries. Fluconazole and amphotericin B are currently available for the treatment of cryptococcal-related infections. However, fluconazole has limited clinical efficacy and amphotericin B requires intravenous infusion and is associated with high renal toxicity. Therefore, there is an unmet need for a new orally administrable anti-cryptococcal drug. We have developed a high-throughput screening assay for the measurement of C. neoformans viability in 1,536-well plate format. The signal-to-basal ratio of the ATP content assay was 21.9 fold with a coefficient of variation and Z' factor of 7.1 % and 0.76, respectively. A pilot screen of 1,280 known compounds against the wild-type C. neoformans (strain H99) led to the identification of four active compounds including niclosamide, malonoben, 6-bromoindirubin-3′-oxime, and 5-[(4-ethylphenyl)methylene]-2-thioxo-4-thiazolidinone. These compounds were further tested against nine clinical isolates of C. neoformans, and their fungicidal activities were confirmed. The results demonstrate that this miniaturized C. neoformans assay is advantageous for the high-throughput screening of large compound collections to identify lead compounds for new anti-cryptococcal drug development.     

Development of a new correlation to calculate permeability for flows with high Knudsen number

Flows with high Knudsen number play a prominent role in many engineering applications. The present study is an effort toward the simulation of flow with high Knudsen number using modified lattice Boltzmann method(LBM) through a porous medium in a channel. The effect of collision between molecules and solid walls, which is required to accurately simulate transition flow regime, is taken into account using a modified relaxation time. Slip velocity on the wall, which is another significant difficulty in simulating transition flow regime, is captured using the slip reflection boundary condition(SRBC). The geometry of porous medium is considered as in-line and staggered. The results are in good agreement with previous works. A new correlation is obtained between permeability, Knudsen number and porosity for flows in transition flow regimes.