Evaluation of antibacterial property of hydroxyapatite and zirconium oxide‐modificated magnetic nanoparticles against Staphylococcus aureus and Escherichia coli

In the first section of this research, superparamagnetic nanoparticles (NPs) (Fe₃ O₄) modified with hydroxyapatite (HAP) and zirconium oxide (ZrO₂) and thereby Fe₃ O₄ /HAP and Fe₃ O₄ /ZrO₂ NPs were synthesised through co‐precipitation method. Then Fe₃ O₄ /HAP and Fe₃ O₄ /ZrO₂ NPs characterised with various techniques such as X‐ray photoelectron spectroscopy, X‐ray diffraction, scanning electron microscopy, energy dispersive X‐ray analysis, Brunauer–Emmett–Teller, Fourier transform infrared, and vibrating sample magnetometer. Observed results confirmed the successful synthesis of desired NPs. In the second section, the antibacterial activity of synthesised magnetic NPs (MNPs) was investigated. This investigation performed with multiple microbial cultivations on the two bacteria; Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Obtained results proved that although both MNPs have good antibacterial properties, however, Fe₃ O₄ /HAP NP has greater antibacterial performance than the other. Based on minimum inhibitory concentration and minimum bactericidal concentration evaluations, S. aureus bacteria are more sensitive to both NPs. These nanocomposites combine the advantages of MNP and antibacterial effects, with distinctive merits including easy preparation, high inactivation capacity, and easy isolation from sample solutions by the application of an external magnetic field.Inspec keywords: nanocomposites, X‐ray chemical analysis, microorganisms, magnetic particles, scanning electron microscopy, precipitation (physical chemistry), nanomagnetics, X‐ray diffraction, X‐ray photoelectron spectra, nanoparticles, superparamagnetism, iron compounds, antibacterial activity, biomedical materials, nanomedicine, calcium compounds, nanofabrication, Fourier transform infrared spectra, magnetometers, zirconium compoundsOther keywords: antibacterial effects, antibacterial property, superparamagnetic nanoparticles, X‐ray photoelectron spectroscopy, X‐ray diffraction, X‐ray analysis, antibacterial activity, bactericidal concentration, S. aureus bacteria, Staphylococcus aureus, Escherichia coli, hydroxyapatite, coprecipitation method, scanning electron microscopy, energy dispersive X‐ray analysis, Brunauer‐Emmett‐Teller method, Fourier transform infrared spectroscopy, vibrating sample magnetometer, microbial cultivations, nanocomposites     

An experimental investigation of cylindrical wire electrical discharge turning process using Taguchi approach

This paper is concerned with Cylindrical Wire Electrical Discharge Turning processes being especially developed for difficult to machine materials. First, the effects of the machining parameters power, voltage, pulse off time, and spindle rotation rate on the machining performance, which comprises the material removal rate, the surface roughness, and the roundness, was studied. The machining parameters were evaluated by Taguchi's method. In particular, an L₉(3⁴) standard orthogonal array was employed as experimental design while determining the influence on the machining performance using the analysis of variance technique. In a second step, an optimisation of the machining parameters was sought using signal to noise ratio analysis. Therefore, the response surface methodology was determined in a regression analysis, which was used to model the influence of the parameters on the performance. Final experiments with a sophisticated home-made rotary spindle allowed the quantification of the effectiveness of the proposed method.     

Green synthesis of AgCl/Ag3 PO4 nanoparticle using cyanobacteria and assessment of its antibacterial,colorimetric detection of heavy metals and antioxidant properties

In this study, the extract of two strains of cyanobacteria was used for the synthesis of silver nanoparticles (NPs). UV–vis spectroscopy, X‐ray diffraction, dynamic light scattering and field emission scanning electron microscopy (FESEM) analyses were carried out to characterise the NPs. The antioxidant activity and heavy metal detection properties were investigated; moreover, their minimum inhibitory concentration and minimum bactericidal concentration against the multi‐drug resistant bacteria were determined. The most abundant materials in these extracts were carbohydrates, so the biosynthesis of NPs using exopolysaccharide (EPS) was also investigated. The surface plasmon resonance of NPs had a peak at 435 nm and EPS NPs at 350–450 nm. The NPs produced by Nostoc sp. IBRC‐M5064 extract revealed the face‐centred cubic (fcc) structure of AgCl, while NPs of N. pruniforme showed the fcc crystalline structure of Ag₃ PO₄ and AgCl. The FESEM showed the spherical shape of these NPs. The AgCl/Ag₃ PO₄ colloid, in comparison with AgCl, showed better antioxidant activity and antibacterial effect. The heavy metal detection analysis of NPs revealed that the NPs of both stains involved in Hg (NO₃)₂ detection.Inspec keywords: drugs, light scattering, silver, biochemistry, surface plasmon resonance, X‐ray diffraction, silver compounds, antibacterial activity, ultraviolet spectra, nanoparticles, visible spectra, colloids, microorganisms, nanofabrication, field emission scanning electron microscopy, chemical sensors, nanosensorsOther keywords: cyanobacteria, antibacterial detection, colorimetric detection, dynamic light scattering, antioxidant activity, heavy metal detection analysis, silver nanoparticle synthesis, field emission scanning electron microscopy analysis, UV‐visible spectroscopy analysis, X‐ray diffraction analysis, inhibitory concentration, exopolysaccharide, surface plasmon resonance, Nostoc sp. IBRC‐M5064 extract, face‐centred cubic crystalline structure, FESEM, spherical shape, antibacterial effect, multidrug resistant bacteria, wavelength 350.0 nm to 450.0 nm, AgCl‐Ag₃ PO₄ , Ag     

Crystal structure of an angiogenesis inhibitor bound to the FGF receptor tyrosine kinase domain

Angiogenesis, the sprouting of new blood vessels from pre-existing ones, is an essential physiological process in development, yet also plays a major role in the progression of human diseases such as diabetic retinopathy, atherosclerosis and cancer. The effects of the most potent angiogenic factors, vascular endothelial growth factor (VEGF), angiopoietin and fibroblast growth factor (FGF) are mediated through cell surface receptors that possess intrinsic protein tyrosine kinase activity. In this report, we describe a synthetic compound of the pyrido[2,3-d]pyrimidine class, designated PD 173074, that selectively inhibits the tyrosine kinase activities of the FGF and VEGF receptors. We show that systemic administration of PD 173074 in mice can effectively block angiogenesis induced by either FGF or VEGF with no apparent toxicity. To elucidate the determinants of selectivity, we have determined the crystal structure of PD 173074 in complex with the tyrosine kinase domain of FGF receptor 1 at 2.5 A resolution. A high degree of surface complementarity between PD 173074 and the hydrophobic, ATP-binding pocket of FGF receptor 1 underlies the potency and selectivity of this inhibitor. PD 173074 is thus a promising candidate for a therapeutic angiogenesis inhibitor to be used in the treatment of cancer and other diseases whose progression is dependent upon new blood vessel formation.     

Effect of green GO/Au nanocomposite on in‐vitro amplification of human DNA

Recently nanomaterials have attracted interest for increasing efficiency of polymerase chain reaction (PCR) systems. Here, the authors report on the usefulness of green graphene oxide/gold (GO/Au) nanocomposites for enhancement of PCR reactions. In this study, green GO/Au nanocomposite was prepared with Matricaria chamomilla extract as reducing/capping agent for site‐directed nucleation of Au^o atoms on surface of GO sheets. The as‐prepared green GO/Au nanocomposites were then characterised with UV–VIS spectrophotometer and scanning electron microscopy. Later, the effect of these nanocomposites was studied on end‐point and real‐time PCR employed for amplification of human glyceraldehyde‐3‐phosphate dehydrogenase gene. The results indicated that GO/Au nanocomposite can improve both end‐point and real‐time PCR methods at the optimum concentrations, possibly through interaction between GO/Au nanocomposite and the materials in PCR reaction, and through providing increased thermal convection by the GO surface as well as the Au nanostructures. In conclusion, it can be suggested that green GO/Au nanocomposite is a biocompatible and eco‐friendly candidate as enhancer of in‐vitro molecular amplification strategies.Inspec keywords: graphene, molecular biophysics, nucleation, enzymes, gold, nanofabrication, nanocomposites, scanning electron microscopy, nanoparticles, DNA, nanomedicine, ultraviolet spectra, visible spectra, graphene compoundsOther keywords: green GO/Au nanocomposite, polymerase chain reaction systems, green graphene oxide/gold, PCR reaction, as‐prepared green GO/Au nanocomposites, real‐time PCR methods, Au nanostructures, in‐vitro amplification, human DNA, Matricaria chamomilla extract, site‐directed nucleation, Au, CO, CO‐Au     

Different thallium(III) oxide nano-structures from direct thermal decomposition of two thallium(I) coordination polymers

Two thallium(I) coordination polymers, [Tl(3-np)] and [Tl(2,4-dnp)], 3-np⁻ = 3-nitrophenoxide and 2,4-dnp⁻ = 2,4-dinitrophenoxide, have been synthesized and characterized by elemental analyses and IR spectroscopy. Flower-like nano-structure and nano-powders thallium(III) oxide, Tl₂O₃, have been prepared by direct thermal decomposition of two different Tl(I) coordination polymers, [Tl(3-np)] and [Tl(2,4-dnp)]. The nano-materials were characterized by scanning electron microscopy, X-ray powder diffraction (XRD) and IR spectroscopy. The thermal stability of nano-structure Tl₂O₃ was studied by thermal gravimetric and differential thermal analyses and showed that there is no reportable loss of weight in the TGA curves that proves the existence of thallium(III) oxide. This study demonstrates that coordination polymers may be suitable precursors for the preparation of nanoscale materials with different and interesting morphologies.     

Apolipoprotein B is intracellularly associated with an ER-60 protease homologue in HepG2 cells

Two ALLN (N-acetyl-leucyl-leucyl-norleucinal)-sensitive endoplasmic reticulum (ER)-localized proteases (ER-60 and ER-72) were recently purified from rat liver. We used an antibody to rat ER-60 to investigate the possible role of this protease in apolipoprotein B (apoB) degradation. First, immunoprecipitation and immunoblotting experiments with the anti-rat ER-60 antibody suggested that HepG2 cells contain a homologue of ER-60 with an approximate molecular mass of 58-60 kDa. The ER-60 homologue was mostly associated with the luminal contents of HepG2 microsomes. Evidence from co-immunoprecipitation and cross-linking experiments appear to suggest that the ER-60 homologue in HepG2 cells is associated with apoB intracellularly. A small pool of apoB was recovered when HepG2 lysates were subjected to immunoprecipitation with anti-rat ER-60 antibody followed by a second immunoprecipitation with anti-apoB antibody. Furthermore, cross-linking of permeabilized cells with dithiobis(succinimidylpropionate) further demonstrated association of apoB with the ER-60 homologue in HepG2 cells. Three polypeptides with molecular masses of 78, 66, and 50 kDa were consistently found to be associated with apoB as well as the 58-kDa ER-60 homologue. The 78-kDa protein associated with both apoB and ER-60 appeared to represent immunoglobulin heavy chain-binding protein (BiP) based on immunoprecipitation with a monoclonal antibody. Cross-linking and immunoblotting experiments suggested the association of the 78-kDa BiP with both the 58-kDa ER-60 homologue as well as the 550-kDa apoB. In summary, the data suggests that HepG2 cells contain a 58-kDa protein which is homologous to the rat liver ER-60 in size, antigenecity, and intracellular localization. The ER-60 homologue in HepG2 cells appears to be closely associated with apoB, as well as other proteins possibly representing ER chaperones such as BiP. We hypothesize that the ER-60 homologue may be involved in the degradation of apoB in the ER lumen of HepG2 cells.     

Temperature distribution reconstruction in Czochralski crystal growth process

A mechanical geometric crystal growth model is developed to describe the crystal length and radius evolution. The crystal radius regulation is achieved by feedback linearization and accounts for parametric uncertainty in the crystal growth rate. The associated parabolic partial differential equation (PDE) model of heat conduction is considered over the time‐varying crystal domain and coupled with crystal growth dynamics. An appropriately defined infinite‐dimensional representation of the thermal evolution is derived considering slow time‐varying process effects. The computational framework of the Galerkin's method is used for parabolic PDE order reduction and observer synthesis for temperature distribution reconstruction over the entire crystal domain. It is shown that the proposed observer can be utilized to reconstruct temperature distribution from boundary temperature measurements. The developed observer is implemented on the finite‐element model of the process and demonstrates that despite parametric and geometric uncertainties present in the model, the temperature distribution is reconstructed with the high accuracy. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2839–2852, 2014     

Improved Efficiency of Dye‐Sensitized Solar Cells Based on a Single Layer Deposition of Skein‐Like TiO2 Nanotubes

We present a new TiO₂ morphology, featuring high surface area and open structure, synthesized by a two‐step chemical route for the manufacture of dye‐sensitized solar cells (DSSCs). This construct is sets of intertwined one‐dimensional (1D) nanostructures (i.e., nanotubes), so‐called skein‐like nanotubes (NTs). Such morphology is produced by a combination of TiC oxidation and hydrothermal processes. The mesoporous TiO₂ nanoparticles, as the product of TiC oxidation operation, is used as the precursor of hydrothermal process to grow the skein‐like NTs. The effect of processing parameters of TiC oxidation and hydrothermal processes is studied. The skein‐like morphology enables to eliminate the conventional three or fourfold layer deposition process by a single layer deposition of TiO₂ NTs. The novel TiO₂ morphology enhances photon capture of fabricated DSSC by exerting a triple function mechanism including improvement of light scattering, dye sensitization, and electron transport. The presented strategy demonstrates the feasibility of the new concept for improvement of cell efficiency by effective light management.     

Structural and transport properties of polydimethylsiloxane based polyurethane/silica particles mixed matrix membranes for gas separation

Mixed matrix membranes of synthesized polyurethane (PU) based on toluene diisocyanate (TDI), polydimethylsiloxane (PDMS) and polytetramethylene glycol (PTMG) with polyvinyl alcohol based polar silica particles were prepared by solution casting technique. The homogeneity and thermal properties of the prepared PDMS-PU/silica membranes were characterized using scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The SEM micrographs confirmed the distribution of silica particles in the polymer matrix without agglomerations. Gas permeation properties of membranes with different silica contents were studied for pure CO₂, CH₄, O₂, He and N₂ gases. The obtained results indicated the permeability of the condensable and polar CO₂ gas was enhanced whereas permeability of other gases decreased upon increasing the silica content of the mixed matrix membranes. The permeability of CO₂ and its selectivity over N₂ was increased from 68.4 Barrer and 22 in pure PDMS-PU to 96.7 Barrer and 64.4 in the mixed matrix membranes containing 10 wt% of the silica particles.