Nigella sativa oil entrapped polycaprolactone nanoparticles for leishmaniasis treatment

This study is the first to investigate the antileishmanial activities of Nigella sativa oil (NSO) entrapped poly‐ɛ ‐caprolactone (PCL) nanoparticles on Leishmania infantum promastigotes and amastigotes in vitro. NSO molecules with variable initial doses of 50, 100, 150, and 200 mg were successfully encapsulated into PCL nanoparticles identified as formulations NSO1, NSO2, NSO3, and NSO4, respectively. This process was characterised by scanning electron microscope, dynamic light scattering, Fourier transform infrared, encapsulation efficiency measurements, and release profile evaluations. The resulting synthetised nanoparticles had sizes ranging between 200 and 390 nm. PCL nanoparticles encapsulated 98% to 80% of initial doses of NSO and after incubation released approximately 85% of entrapped oil molecules after 288 h. All investigated formulations demonstrated strong antileishmanial effects on L. infantum promastigotes by inhibiting up to 90% of parasites after 192 h. The tested formulations decreased infection indexes of macrophages in a range between 2.4‐ and 4.1‐fold in contrast to control, thus indicating the strong anti‐amastigote activities of NSO encapsulated PCL nanoparticles. Furthermore, NSO‐loaded PCL nanoparticles showed immunomodulatory effects by increasing produced nitric oxide amounts within macrophages by 2–3.5‐fold in contrast to use of free oil. The obtained data showed significant antileishmanial effects of NSO encapsulated PCL nanoparticles on L. infantum promastigotes and amastigotes.Inspec keywords: antibacterial activity, drug delivery systems, nanofabrication, nitrogen compounds, nanomedicine, microorganisms, cellular biophysics, diseases, scanning electron microscopy, oils, polymers, biomedical materials, nanoparticles, encapsulation, Fourier transform infrared spectraOther keywords: encapsulation efficiency measurements, entrapped oil molecules, investigated formulations, NSO‐loaded PCL nanoparticles, Nigella sativa oil entrapped polycaprolactone nanoparticles, antileishmanial activities, poly‐ε‐caprolactone nanoparticles, scanning electron microscope, DLS, Fourier transform infrared, release profile evaluations, Leishmania infantum promastigotes, Leishmania infantum amastigotes, parasites, infection, infection indexes, macrophages, immunomodulatory effects, time 288.0 hour, time 192.0 hour, mass 50.0 mg, mass 100.0 mg, mass 150.0 mg, mass 200.0 mg, size 200.0 nm to 390.0 nm     

Markov Models of Queueing–Inventory Systems with Variable Order Size

Markov models of queueing–inventory systems with variable order size are investigated. Two classes of models are considered: with instant service and with nonzero service time. The model with nonzero service time assumes that impatient customers can form a queue of either finite or infinite length. The exact and approximate methods are developed to calculate the characteristics of the systems under proposed restocking policy.     

One‐step synthesis of triarm block copolymers via simultaneous reversible‐addition fragmentation chain transfer and ring‐opening polymerization

One‐step synthesis of star copolymers by reversible addition–fragmentation chain transfer (RAFT) and ring‐opening polymerization (ROP) by using a novel dual initiator is reported. Triarm block copolymers comprising one polystyrene (or polyacrylamide) arm and two poly(β‐butyrolactone) arms were synthesized in one‐step by simultaneous RAFT polymerization of styrene (St) (or acrylamide, designated as AAm) and ROP of β‐butyrolactone (BL) in the presence of a novel trifunctional initiator, 1,2‐propanediol ethyl xanthogenate (RAFT‐ROP agent). This dual initiator was obtained through the reaction of 3‐chloro‐1,2‐propanediol with the potassium salt of ethyl xanthogenate. The principal parameters such as monomer concentration, initiator concentration, and polymerization time that affect the one‐step polymerization reaction were evaluated. The characterization of the products was achieved using Fourier‐transform infrared spectroscopy (FTIR), ¹H‐nuclear magnetic resonance (¹H‐NMR), ¹³C‐nuclear magnetic resonance (¹³C‐NMR), Gas chromatography–mass spectrometry (GC–MS), gel‐permeation chromatography (GPC), thermogravimetric analysis (TGA), and fractional precipitation (γ) techniques. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis,structure, and thermo‐physical properties of Fe2O3.Al2O3 and polyethylene nanocomposites

In this study, Fe₂O₃.Al₂O₃/polyethylene composites were prepared using a two‐step process. In the first step, PE is synthesized using titanium based metallocene catalyst system. While the synthesized PE was subsequently purified, hydrated alumina filled PE (MHFP) composites was formed by the hydrolysis of methylaluminoxane (MAO). In the second step, Fe₂O₃.Al₂O₃/PE was prepared via thermal decomposition of ferric formate in a high temperature solution of MHFP composite. The structure, morphology, and thermal properties of the composites were characterized using the XRD, FTIR, SEM‐EDX, TGA, and DSC analytical techniques. Results showed that the incorporation of a suitable amount of Fe₂O₃.Al₂O₃ into the composites enhances the thermal stability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The multiple-site nature of ethylene polymerization catalysts based on zirconyl carboxylates

Zirconyl carboxylates in combination with alkylaluminum chlorides were shown to be active catalysts for the reaction of ethylene polymerization. It was found that the molecular-mass distribution of ethylene oligomers depends considerably on the donor-acceptor properties of a modifier of the catalytic system. The optimal conditions for obtaining the C₄–C₈ and C₈–C₁₈ fractions of linear α-olefins with yields of 75–80%, respectively, were determined. Experimentally observed deviation of the composition of oligomerization products from the statistical distribution of the Schulz-Flory type is caused by the multistie character of the catalytic system used. Modifiers that provide the formation of catalytic centers with higher coordination unsaturation (type I) promote the selective formation of the C₄–C₈ fraction (95%). Modifiers capable of forming semilabile ligands (type II) lead to an increase in the yield of the middle, C₆–C₁₀ and C₈–C₁₈ fractions. Modifiers with stronger chelating properties (type III) direct the process toward the formation of macromonomers and polymers of ethylene.     

Importance of correcting the protein, fat and vitamin content of the diets for the work capacity of young people during exams

Study of the working capacity of young people fed various rations during examinations has shown that the examinations considerably affected a number of psychophysiologic characteristics. Addition of olive and particularly sunflower oil (20 g daily) into the rations promoted neuro-reflex activation, that manifested in reduced time of sensory motor reactions; attention function also improved. Intake of vitamin B2 (0.01 g daily) and particularly undevite (3 dragees daily) contributed to improvement of attention function, as well as of working capacity. High milk protein balanced rations helped to reduce the unfavourable effects of examination stress on the body. Students of this group have shown the working capacity and attention practically the same as during routine studies, both being much higher than in students on traditional nutrition. Intake of undevite contributed to a further improvement of the psychophysiological parameters.     

Singular controls in a given stepwise control problem

The Goursat-Darboux stepwise problem of systems control, i.e., the multi-stage problem of control of systems with distributed parameters, is considered. Second-order formulas for the increment in the quality functional are constructed. In investigating these formulas on needle variations in the control, a number of necessary Pontryagin maximum principle-type optimality conditions is obtained and a singular case is studied.     

Novel Economically Alloyed Steel for Liquefied Natural Gas Equipment and its Heat Treatment Regime

Metal Science and Heat Treatment - Heat treatment is developed for commercial rolled thick sheets of cryogenic steel for liquefied natural gas equipment. It is shown that treatment guarantees the...