Effect of partial charge parametrization on the fluid phase behavior of hydrogen sulfide

The effect of partial charge parametrization on the fluid phase behavior of hydrogen sulfide is investigated with grand canonical histogram reweighting Monte Carlo simulations. Four potential models, based on a Lennard-Jones + point charge functional form, are developed. It is shown that Lennard-Jones parameters can be tuned such that partial charges for the sulfur atom in the range -0.40 < q(s) < -0.252 will lead to an accurate reproduction of experimental vapor-liquid equilibria. Each of the parameter sets developed in this work are used to predict the pressure composition behavior H2S-n-pentane at 377.6 K. While the mixture calculation provides a means of reducing the number of candidate parameter sets, multiple parameter sets were found to yield an excellent reproduction of both the pure component and mixture phase behavior.     

Tidal Forces in Dyonic Reissner-Nrdstrom Black Hole

This paper investigates the tidal as well as magnetic charge effects produced in dyonic Reissner-Nordstr¨om black hole.We evaluate Newtonian radial acceleration using radial geodesics for freely falling test particles.We establish system of equations governing radial and angular tidal forces using geodesic deviation equation and discuss their solutions for bodies falling freely towards this black hole.The radial tidal force turns out to be compressing outside the event horizon whereas the angular tidal force changes sign between event and Cauchy horizons unlike Schwarzschild black hole.The radial geodesic component starts decreasing in dyonic Reissner-Nordstr¨om black hole unlike Schwarzschild case.We conclude that magnetic charge strongly affects the radial as well as angular components of tidal force.     

Attenuative Effects of Fluoxetine and Triticum aestivum against Aluminum-Induced Alzheimer’s Disease in Rats: The Possible Consequences on Hepatotoxicity and Nephrotoxicity

Background: Alzheimer’s disease (AD) is a chronic neurological illness that causes considerable cognitive impairment. Hepatic and renal dysfunction may worsen AD by disrupting β-amyloid homeostasis at the periphery and by causing metabolic dysfunction. Wheatgrass (Triticum aestivum) has been shown to have antioxidant and anti-inflammatory properties. This work aims to study the effect of aluminum on neuronal cells, its consequences on the liver and kidneys, and the possible role of fluoxetine and wheatgrass juice in attenuating these pathological conditions. Method: Rats were divided into five groups. Control, AD (AlCl₃), Fluoxetine (Fluoxetine and AlCl₃), Wheatgrass (Wheatgrass and AlCl₃), and combination group (fluoxetine, wheatgrass, and AlCl₃). All groups were assigned daily to different treatments for five weeks. Conclusions: AlCl₃ elevated liver and kidney enzymes, over-production of oxidative stress, and inflammatory markers. Besides, accumulation of tau protein and Aβ, the elevation of ACHE and GSK-3β, down-regulation of BDNF, and β–catenin expression in the brain. Histopathological examinations of the liver, kidney, and brain confirmed this toxicity, while treating AD groups with fluoxetine, wheatgrass, or a combination alleviates toxic insults. Conclusion: Fluoxetine and wheatgrass combination demonstrated a more significant neuroprotective impact in treating AD than fluoxetine alone and has protective effects on liver and kidney tissues.     

Cone calorimeter analysis of flame retardant poly (methyl methacrylate)-silica nanocomposites

Nanocomposite is a promising method to reduce fire hazards of polymers. Specifically due to increased interfacial area between polymer and nanofillers, polymer nanocomposites have an advantage in reducing fire hazards efficiently even when the flame retardant additives are at a concentration of 5 mass% or less. In theory, crosslinking between the polymer chains can create a carbon-dense structure to enhance char formation, which can further promote the flame retardancy. However, little research has been done to explore the flammability of crosslinking polymer nanocomposites with a low concentration of nanosilica particles. In this study, crosslinked and non-crosslinked poly (methyl methacrylate) (PMMA) nanocomposites of a low concentration of nanosilica particles have been prepared via an in situ method. Their fire properties were tested by using the cone calorimeter at the heat flux of 50 kW m^?2. Although silica-containing flame retardants tend to negatively affect the ignitability and soot production especially at a high concentration, through the condensed phase mechanism, the samples of high loading rate of nanosilica particles show better fire retardancy performance in the aspect of flammability, including decreased heat release rate, mass loss rate, and total heat release. Additionally, crosslinking indeed attributes to the less intensive combustion of crosslinked PMMA samples, especially at a low concentration of nanosilica. The combination of nanosilica particles with the modification of the internal structure of the polymer nanocomposites might be a good strategy to improve fire retardancy.     

The Effect of Blood Contamination on the Chemical Characterization of Hydrated Mineral Trioxide Aggregates and Their Dentin-Interface: A Comparative Study

The presence of blood contamination could affect the chemical characterization of mineral trioxide aggregates as endodontic repair material during surgical approach. The aim of this study was to assess and compare the chemical characterization of two white mineral trioxide aggregates (ProRoot and Angelus) mixed with blood versus water. ProRoot and Angelus were mixed with either distilled water, fresh human blood, or diluted blood and analyzed using Fourier transform infrared spectroscopy. The same materials were packed inside holes in dentin blocks for scanning electron microscopy with energy-dispersive X-ray. Gray Portland cement was used as a control. The infrared spectra of unhydrate powders showed an increase in alite in ProRoot and Angelus, belite in Portland cement, and calcium hydroxide in Angelus. Upon hydration, changes in these bands were detected. Energy-dispersive X-ray displayed significantly higher calcium, aluminum, and phosphorous in hydrated Angelus and silicon in hydrated ProRoot (p < 0.05). No phosphorous was detected in ProRoot. Traces of iron were detected in blood groups. A granular pattern was observed at the hydrated material of all tested groups. Definitive gaps were detected at certain areas within hydrated material and its dentin-interface, particularly in blood-contaminated groups. It was supported with the appearance of new bands assigned to Amide I and II of blood protein. It was concluded that the presence of blood during the hydration process of mineral trioxide aggregates produced small gaps of protein impurities within the hydrated material, affecting its chemical behavior and dentin/material-interface integrity.     

Cyanogen bromide cleavage generates fragments suitable for expressed protein and glycoprotein ligation

Herein cyanogen bromide is employed for the efficient production of N-terminal cysteine containing protein fragments for expressed protein ligation (EPL) from polyhistidine-tagged precursors. We provide three examples of efficient CNBr cleavage of fragments of the glycoprotein erythropoietin that can be ligated with peptides or glycopeptide mimetics potentially giving rise to semisynthetic glycoprotein therapeutics.     

Leufolins A and B, potent butyrylcholinesterase-inhibiting flavonoid glucosides from Leucas urticifolia

New flavonoidal glucosides leufolins A (1) and B (2), have been isolated from the ethyl acetate soluble fraction of the whole plants of Leucas urticifolia. Their structures were elucidated on the basis of extensive analysis of nuclear magnetic resonance (1D and 2D NMR) spectral data. Both of these compounds exhibited significant inhibitory potential against the enzyme butyrylcholinesterase.     

Photoprotective effects of bucillamine against UV-induced damage in an SKH-1 hairless mouse model

UVB exposure of skin results in various biologic responses either through direct or indirect damage to DNA and non-DNA cellular targets via the formation of free radicals, reactive oxygen species (ROS) and inflammation. Bucillamine [N-(2-mercapto-2-methylpropionyl)-l-cysteine] is a cysteine-derived compound that can replenish endogenous glutathione due to its two donatable thiol groups, and functions as an antioxidant. In this study, we investigated the effects of bucillamine on UVB-induced photodamage using the SKH-1 hairless mouse model. We have demonstrated that UVB exposure (two consecutive doses, 230 mJ cm(-2)) on the dorsal skin of SKH-1 mice induced inflammatory responses (edema, erythema, dermal infiltration of leukocytes, dilated blood vessels) and p53 activation as early as 6 h after the last UVB exposure. Bucillamine pretreatment (20 mg kg(-1) of body weight, administered subcutaneously) markedly attenuated UVB-mediated inflammatory responses and p53 activation. We have also demonstrated that the stabilization and upregulation of p53 by UVB correlated with phosphorylation of Ser-15 and Ser-20 residues of p53 protein and that bucillamine pretreatment attenuated this effect. We propose that bucillamine has potential to be effective as a photoprotective agent for the management of pathologic conditions elicited by UV exposure.     

Bioactive phenolic amides from Celtis africana

Nine compounds have been isolated for the first time from Celtis africana, namely trans-N-coumaroyltyramine (1), trans-N-feruloyltyramine (2), trans-N-caffeoyltyramine (3), lauric acid (4), oleic acid (5), palmitic acid (6), lupeol (7), β-sitosterol (8) and oleanolic acid (9), respectively. Their structures have been elucidated by different spectroscopic techniques. The isolated compounds were screened for their antioxidant, anti-inflammatory and acetylcholinestrease enzyme inhibitory activities. Compounds 1-3 showed significant antioxidant and anti-inflammatory activities and weak to moderate acetylcholinestrease enzyme inhibition activity.