Chemical characterization and therapeutic properties of Achillea biebersteinii leaf aqueous extract synthesized copper nanoparticles against methamphetamine-induced cell death in PC12: A study in the nanotechnology and neurology fields

Recently, scientist have used metallic nanoparticles for synthesizing many new drugs in the field of neurology. One of the metals used in the metallic nanoparticles is copper. The role of Achillea biebersteinii in increasing the physiological activities of central nervous system in Iranian traditional medicine is well known. In this study fresh leaves of A. biebersteinii were used for the biosynthesis of copper nanoparticles. We also assessed the effect of copper nanoparticles on methamphetamine-induced cell death in the PC12 cell line. The nanoparticles were analyzed by Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, field emission scanning electron microscopy, and ultraviolet–visible spectroscopy. A 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging experiment was carried out to assess the antioxidant properties of Cu(NO₃)₂, A. biebersteinii, and CuNPs. The DPPH test revealed similar antioxidant activities for A. biebersteinii, CuNPs, and butylated hydroxytoluene. In the cellular and molecular part of the present study, the Trypan blue test was performed to assess cell viability. The terminal deoxynucleotidyl transferase 2′-Deoxyuridine, 5′-Triphosphate (dUTP) nick end labeling test clarified the DNA fragmentation and apoptosis occurrence. The Griess reaction was used to measure nitric oxide production and caspase-3 activity was evaluated by spectrophotometry. The obtained results were fed into SPSS-22 software and analyzed by one-way ANOVA, followed by Tukey's post hoc test (p ≤ 0.01). The results indicate that both doses of CuNPs had cell death-suppressing effects on nerve cells. In particular, both doses of CuNPs significantly (p ≤ 0.01) increased cell viability and NO production, and decreased cell cytotoxicity, cell death index, and caspase-3 activity near the normal. According to these results, it seems that CuNPs could be administrated as a neuroprotective supplement or drug for the treatment of central nervous system disorders in clinical trials.     

Online estimation and adaptive control for a class of history dependent functional differential equations

Nonlinear Dynamics - This paper presents sufficient conditions for the convergence of online estimation methods and the stability of adaptive control strategies for a class of history-dependent,...     

High‐Temperature Study of 2‐Methyl Furan and 2‐Methyl Tetrahydrofuran Combustion

The ignition behavior of methyl furan (2‐MF) and methyl tetrahydrofuran (2‐MTHF) is investigated using the shock tube technique. Experiments are carried out using homogeneous gaseous mixtures of fuel, oxygen, and argon with equivalence ratios, ?, of 0.5, 1.0, and 2.0 at average pressures of 3 and 12 atm over a temperature range of 1060–1300 K. In addition to ignition delay time measurements, fuel concentration time histories during ignition and pyrolysis of 2‐MTHF are obtained by means of laser absorption spectroscopy using a He–Ne laser at a fixed wavelength of 3.39 µm. With respect to ignition delay times, it is observed that under similar conditions of equivalence ratio and argon/oxygen ratio (D), 2‐MTHF has longer ignition delay times than 2‐MF at 3 atm. In addition, 2‐MTHF has longer ignition delay times than 2‐MF at higher temperatures for the case of 12 atm and under the same conditions of ? and D. The higher reactivity of 2‐MF, as indicated by shorter ignition delay times, is attributed to differences in chemical structure, whereby weaker C–H bond sites are more readily susceptible to radical attack than in 2‐MTHF. It is observed that ignition delay times of 2‐MTHF decrease with increasing equivalence ratio at 12 atm for fixed argon/oxygen ratio. Ignition delay times are compared with model predictions using recent chemical kinetic models of both fuels, showing that both models generally predict shorter ignition delay times than measured. The relatively higher absorption cross section of 2‐MTHF at 3.39 µm allows for its concentration time histories to be determined and compared to model predictions. In line with the observed discrepancy in ignition predictions, predicted 2‐MTHF concentration profiles are such that the fuel is shown to be more rapidly consumed than observed in the experiments. The study advances understanding of the combustion chemistry of these cyclic ethers that are potential alternative fuels.     

Efficient three-step synthesis of benzo[e]imidazo[1,2-c][1,2,3]triazines

A novel three-step sequence toward benzo[e]imidazo[1,2-c][1,2,3]triazine derivatives is investigated. This pathway started from commercially available starting materials afforded 5a–h in good to excellent yields. In this method, we took the advantage of diazonium chemistry, which was followed by intramolecular N-N bond formation in the construction of N-rich cycles.     

Hydrogen exchange mass spectrometry as an analytical tool for the analysis of amyloid fibrillogenesis

In this study, we have used glucagon as a model system for analyzing amyloid fibrillogenesis by hydrogen exchange MALDI mass spectrometry (HXMS). The hydrogen exchange mass spectrometry data correlated well with the traditional method based on Thioflavin T fluorescence and provided quantitative information by measuring the fibrillating molecules directly. The hydrogen exchange mass spectrometry data collected during fibrillogenesis revealed that glucagon fibrillation was a two component system showing an on/off type of interaction where only monomeric and fibrils were present without any substantial amount of intermediate species. This was evident by the extensive deuteration of the monomer and protection of the entire 29 residue glucagon peptide upon fibrillation.. The method complements the traditional procedures and has the potential to provide new information with respect to the nature of transient species, the structure of the growing fibrils and the mechanism of formation.     

Electrospun terpolymeric nanofiber membrane for micro solid‐phase extraction of diazinon and chlorpyrifos from aqueous samples

The present study deals with the synthesis and electrospining of a new terpolymer nanofiber in order to determine the amount of diazinon and chlorpyrifos in water and fruit juice samples. The synthesized terpolymer and the prepared nanofiber were characterized using ¹H NMR spectroscopy, FTIR spectroscopy, scanning electron microscopy, and gel permeation chromatography. The performance of terpolymer nanofiber, prepared as a sorbent for micro solid phase extraction was investigated for the extraction of diazinon and chlorpyrifos from aquaeous media. Then, the target analytes were desorbed from the coating with an organic solvent and analyzed by gas chromatography with flame ionization detector. Extraction efficiencies were significant (>90%) under the optimum condition. The proposed method also demonstrated good linear dynamic ranges for diazinon and chlorpyrifos (3–250 and 5–200 µg/L), and low limit of detections (0.5 and 0.7 µg/L) respectively. Moreover, under optimum condition for extraction of diazinon and chlorpyrifos, square of correlation coefficients (R²) of 0.9978 and 0.9953 and relative standard deviations of 4.6 and 5.1% were achieved, respectively. The recoveries for diazinon and chlorpyrifos were in the range of 85–97%.     

Selective arylation of 1,1-disubstituted olefins using a biphenyl-based phosphine in Heck coupling reactions

The biphenyl-based phosphine, 2-diphenylphosphino-2′-methylbiphenyl is an effective ligand for palladium-catalyzed terminal arylation of 1,1-disubstituted olefins with aryl bromides in DMF and K₂CO₃ as base. The yields of products are independent of the electronic properties of the aryl bromides, however, the nature of the olefin has a major effect.     

Non-resonant microwave absorption studies of superconducting MgB2 and MgB2 + MgO

Non-resonant microwave absorption (NRMA) studies of superconducting MgB₂ and a sample containing ∼10% by weight of MgO in MgB₂ are reported. The NRMA results indicate near absence of intergranular weak links in the pure MgB₂ sample. A linear temperature dependence of the lower critical field H _c1 is observed indicating a non-s wave superconductivity. However, the phase reversal of the NRMA signal which could suggest d wave symmetry is also not observed. In the MgB₂ + MgO sample, much larger low field dependent absorption is observed indicating the presence of intergranular weak links. The hysteretic behavior of NRMA is compared and contrasted in the two samples. In the pure MgB₂ sample, a large hysteresis is observed between the forward and the reverse scans of the magnetic field indicating strong pinning of flux lines. This hysteresis saturates a few degrees below T _c while in the MgB₂ + MgO sample, a much slower increase of hysteresis with decreasing temperature is observed, a signature of weaker pinning.     

The role of inner and internal radiation on the melt growth of sapphire crystal

In this paper, for an inductively heated Czochralski furnace used to grow sapphire single crystal, influence of the inner (wall‐to‐wall) and crystal internal (bulk) radiation on the characteristics of the growth process such as temperature and flow fields, structure of heat transfer and crystal‐melt interface has been studied numerically using the 2D quasi‐steady state finite element method. The obtained results of global analysis demonstrate a strong dependence of thermal field, heat transport structure and crystal‐melt interface on both types of radiative heat transfer within the growth furnace.