Increasing the aqueous solubility of acetaminophen in the presence of polyvinylpyrrolidone and investigation of the mechanisms involved

It was shown that the aqueous solubility of acetaminophen in the presence of polyvinylpyrrolidone (PVP) increased. The solubility at 25°C increased from 14.3 mg mL^-1 in the absence of PVP, to 19.7 mg mL^-1 in the presence of 4% w/v PVP, and to 26.7 mg mL^-1 in the presence of 8% w/v PVP. Dialysis studies indicated that there is a potential of binding between PVP and acetaminophen in their aqueous solutions. Dialysis studies also revealed that the nature of interaction between PVP and acetaminophen is physical and reversible, and there was no strong binding between PVP and acetaminophen in their solutions. Infrared spectroscopy of acetaminophen/PVP solid dispersion indicated that the mechanism of interaction between PVP and acetaminophen is via hydrogen bonding. Therefore, the increase in solubility of acetaminophen in the presence of PVP is probably attributed to its ability to form a water-soluble complex with PVP.     

A new sensor for the simultaneous determination of paracetamol and mefenamic acid in a pharmaceutical preparation and biological samples using copper(II) doped zeolite modified carbon paste electrode

A new chemically modified electrode is constructed based on a copper(II) doped zeolite modified carbon paste electrode (Cu²⁺Y/ZMCPE). It is demonstrated that this novel sensor could be used for the simultaneous determination of the pharmaceutically important compounds paracetamol (PAR) and mefenamic acid (MEF). The measurements were carried out using the differential pulse voltammetry (DPV) method. The prepared modified electrode shows voltammetric responses of high sensitivity, selectivity and stability for PAR and MEF under optimal conditions, which makes it a suitable sensor for simultaneous submicromolar detection of PAR and MEF in solution. The oxidation peak current for PAR in Briton Robinson buffer (pH = 10) was measured at various concentrations between 0.25 and 900 μM. (The detection limit was 0.1 μM and S/N was 3.) It proved linear (the correlation coefficient was 0.9987). For the MEF a linear correlation between oxidation peak current and concentration of MEF over the range 0.3–100 μM, with a correlation coefficient of 0.9991 and a detection limit of 0.04 μM, was obtained. The analytical performance of this sensor has been evaluated for the detection of PAR and MEF in human serum, human urine and a pharmaceutical preparation.     

Spatial-temporal dual-actor CNN for human interaction prediction in video

Multimedia Tools and Applications - Predicting the interaction between two humans, when viewed as a part of video is one of the most challenging issues in the field of computer vision, due to its...     

Corrosion protection by zirconia-based thin films deposited by a sol–gel spin coating method

This paper focuses on the structure and corrosion behavior of 316L stainless steel coated by inorganic ZrO₂, hybrid ZrO₂–PMMA, and combined inorganic–hybrid films. The coatings were deposited by a particulate sol–gel spin-coating route, using carboxymethyl cellulose as a nanoparticle dispersant. The electrochemical evaluations were conducted in a simulated body fluid, via potentiodynamic polarization and impedance spectroscopic experiments. According to the results, the hybrid coating presented a better corrosion protection compared to the inorganic coating, due to a lesser density of structural defects. However, the best corrosion resistance was found for a combined coating which consists of an inorganic bottom layer and a hybrid top layer, due to a desirable compromise of good adhesion and low defect density.     

The Interaction of Human and Epstein–Barr Virus miRNAs with Multiple Sclerosis Risk Loci

Although the causes of Multiple Sclerosis (MS) still remain largely unknown, multiple lines of evidence suggest that Epstein–Barr virus (EBV) infection may contribute to the development of MS. Here, we aimed to identify the potential contribution of EBV-encoded and host cellular miRNAs to MS pathogenesis. We identified differentially expressed host miRNAs in EBV infected B cells (LCLs) and putative host/EBV miRNA interactions with MS risk loci. We estimated the genotype effect of MS risk loci on the identified putative miRNA:mRNA interactions in silico. We found that the protective allele of MS risk SNP rs4808760 reduces the expression of hsa-mir-3188-3p. In addition, our analysis suggests that hsa-let-7b-5p may interact with ZC3HAV1 differently in LCLs compared to B cells. In vitro assays indicated that the protective allele of MS risk SNP rs10271373 increases ZC3HAV1 expression in LCLs, but not in B cells. The higher expression for the protective allele in LCLs is consistent with increased IFN response via ZC3HAV1 and so decreased immune evasion by EBV. Taken together, this provides evidence that EBV infection dysregulates the B cell miRNA machinery, including MS risk miRNAs, which may contribute to MS pathogenesis via interaction with MS risk genes either directly or indirectly.     

Microstructural analysis of YSZ and YSZ/Al2O3 plasma sprayed thermal barrier coatings after high temperature oxidation

Air plasma sprayed TBCs usually include lamellar structure with high interconnected porosities which transfer oxygen from YSZ layer towards bond coat and cause TGO growth and internal oxidation of bond coat.The growth of thermally grown oxide (TGO) at the interface of bond coat and ceramic layer and internal oxidation of bond coat are considered as the main destructive factors in thermal barrier coatings.Oxidation phenomena of two types of plasma sprayed TBC were evaluated: (a) usual YSZ (yttria stabilized zirconia), (b) layer composite of (YSZ/Al₂O₃) which Al₂O₃ is as a top coat over YSZ coating. Oxidation tests were carried out on these coatings at 1100°C for 22, 42 and 100h. Microstructure studies by SEM demonstrated the growth of TGO underneath usual YSZ coating is higher than for YSZ/Al₂O₃ coating. Also cracking was observed in usual YSZ coating at the YSZ/bond coat interface. In addition severe internal oxidation of the bond coat occurred for usual YSZ coating and micro-XRD analysis revealed the formation of the oxides such as NiCr₂O₄, NiCrO₃ and NiCrO₄ which are accompanied with rapid volume increase, but internal oxidation of the bond coat for YSZ/Al₂O₃ coating was lower and the mentioned oxides were not detected.     

Nickel–cobalt alloy nanosheets obtained from reductive hydrothermal-treatment of nickel–cobalt hydroxide carbonate

Nickel–cobalt hydroxide carbonate, a layered material was synthesized by the co-precipitation method using urea as precipitant agent. This anionic layered material with hexagonal structure is constructed from nickel and cobalt ions within the layers and carbonate anions between the layers. Nickel–cobalt alloy with pure cubic phase was obtained by a reductive hydrothermal-treatment of the layered precursor. Powder X-ray diffraction pattern and Fourier transform infrared spectroscopy confirmed the formation of the initial layered material and its metallic alloy product. That is, the nickel–cobalt alloy has really produced via a wet chemical route for the first time. Magnetic measurement revealed that the alloy sample is a soft magnet material.     

Tableting of Eudragit RS and propranolol hydrochloride solid dispersion: effect of particle size, compaction force, and plasticizer addition on drug release

The application of a solid dispersion (SD) system of propranolol HCl and Eudragit RS was evaluated in the preparation of prolonged release tablets. The effects of SD size fraction, compaction force, and inclusion of plasticizers [namely diethylphtalate (DEP) and triethylcitrate (TEC)] on crushing strengths of matrices and release profile of drug were also investigated. The results showed that when compressed as a tablet, the SD system was more efficient in prolonging drug release than physical mixture. This effect was due to formation of much harder tablets of the SD system (crushing strength 8.5 kg) compared with those of physical mixtures (crushing strength 2.7 kg). All matrices of the SD system showed release rate patterns that were best described by the Higuchi equation. It was also shown that the rate of drug release decreased from 19.8% to 9.13% min^- 1/2 as the SD size fraction decreased from 300-350 to 125-250 µm. However, further reduction of size fraction did not significantly affect tablet crushing strength and drug release rate. Increase in compaction force from 5 to 30 kN increased the crushing strength of matrices from 2.9 to 13.6 kg. However, the rate of drug release remained nearly unchanged beyond compaction pressure of 10 kN, indicating that crushing strength of matrices in the range of 8.5-13.6 kg did not affect drug release rate. The addition of 5% or 10% of either plasticizer (DEP or TEC) led to an increase in crushing strength of matrices and more retardation of drug release. This effect was more pronounced for higher concentrations of plasticizers. This effect was probably due to more plastic deformation of matrices under the compaction force, which helped matrices to retain their shape throughout the dissolution test.     

Peculiar effect of polyethylene glycol in comparison with triethyl citrate or diethyl phthalate on properties of ethyl cellulose microcapsules containing propranolol hydrochloride in process of emulsion-solvent evaporation

Plasticizers play a crucial role in various process of microencapsulation. In this study, the effect of incorporation of plasticizer in process of emulsion solvent evaporation was investigated on properties of ethyl cellulose (EC) microcapsules containing propranolol hydrochloride. The effect of plasticizer type and concentration were investigated on characteristics of microcapsules prepared from different viscosity grades of EC. Product yield, encapsulation efficiency, mean particle size, shape, surface characteristics, solid state of drug, and drug release profiles were evaluated. Product yield and encapsulation efficiency were not dependent on plasticizer type and concentration. However, encapsulation efficiency decreased with increase in EC viscosity grade in the most of the cases. The mean particle size was in the range of 724–797?μm and was not dependent on plasticizer type. Microcapsules formed in the presence of PEG had a very smooth surface with few pores. XRD and DSC studies revealed a reduction of drug crystallinity after microencapsulation especially in presence of PEG. The results showed that the presence of TEC and DEP with different concentrations had no marked effect on drug release from microcapsules containing different viscosity grades of EC. This was not the case when PEG was used, and despite its water solubility it reduced the drug release rate noticeably. The reduction in the drug release in the presence of PEG was concentration-dependent. The use of PEG as a plasticizer in process of emulsion solvent evaporation highly improved the EC microcapsule structure and retarded the drug release rate and therefore is recommended.     

Surelease as granulating liquid in preparation of sustained release matrices of ethylcellulose and theophylline

Objectives: Use of Surelease as a granulation liquid in preparation of granules and matrices of theophylline and ethylcellulose was evaluated.

Materials and methods: Physical mixtures (at 1:1 or 1:1.5 drug:polymer) were granulated using water, Surelease or diluted Surelease as granulating liquid. The granule characteristics (shape, size, flow rate, mechanical properties, friability and release profile) were studied. Afterwards, matrices were manufactured and their crushing strengths, friability and release profiles were determined.

Results: Granulation produced agglomerated particles with better flowability than physical mixtures. Change of granulation liquid from water to Surelease or diluted Surelease led to the marginal increase in size of granules at 1:1 drug:polymer, however, the flow rate and Carr’s index were considerably improved. The hardness, elastic modulus, friability and rate of drug release were not affected by granulation liquid. Increase in polymer content resulted in reduction in size of granules, flow rate, elastic modulus and rate of drug release. However hardness of the granules was unaffected. Granulation process and granulation liquid did not affect the hardness, and dissolution rate of matrices at 1:1 drug:polymer, while the use of Surelease or diluted Surelease as a granulating liquid, increased the hardness and decreased drug release rate at 1:1.5 drug:polymer. Matrices prepared from Surelease or diluted Surelease showed similar characteristics.

Conclusions: Surelease is a suitable granulating liquid for preparation of ethylcellulose matrices especially when high amount of polymer is used and could not only improve the flow and compatibility of the granules, but also help in reducing the rate of drug release.