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     

Aligned Carbon Nanotube–Based Flexible Gel Substrates for Engineering Biohybrid Tissue Actuators

Muscle‐based biohybrid actuators have generated significant interest as the future of biorobotics but so far they move without having much control over their actuation behavior. Integration of microelectrodes into the backbone of these systems may enable guidance during their motion and allow precise control over these actuators with specific activation patterns. Here, this challenge is addressed by developing aligned carbon nanotube (CNT) forest microelectrode arrays and incorporating them into scaffolds for cell stimulation. Aligned CNTs are successfully embedded into flexible and biocompatible hydrogels exhibiting excellent anisotropic electrical conductivity. Bioactuators are then engineered by culturing cardiomyocytes on the CNT microelectrode‐integrated hydrogel constructs. The resulting cardiac tissue shows homogeneous cell organization with improved cell‐to‐cell coupling and maturation, which is directly related to the contractile force of muscle tissue. This centimeter‐scale bioactuator has excellent mechanical integrity, embedded microelectrodes, and is capable of spontaneous actuation behavior. Furthermore, it is demonstrated that a biohybrid machine can be controlled by an external electrical field provided by the integrated CNT microelectrode arrays. In addition, due to the anisotropic electrical conductivity of the electrodes provided by aligned CNTs, significantly different excitation thresholds are observed in different configurations such as the ones with electrical fields applied in directions parallel versus perpendicular to the CNT alignment.     

Antibacterial flexographic ink containing silver nanoparticles

The current work deals with the effects of incorporation of silver nanoparticles on the antibacterial and the thermal properties of a flexographic ink. The stable and uniform dispersion of silver nanoparticles in the ink were confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The thermal properties of the pure and nanoparticle loaded ink films were also evaluated using TGA and DSC techniques. The results from this study proved acceptable dispersion characteristics, wherein, the flexographic ink showed a significant antibacterial activity against Gram-positive and Gram-negative bacteria     

Estimation of reactivity ratios of styrene/butyl acrylate copolymer by ordinary and generalized least square methods

A novel generalized least square (GLS) estimator program was employed for determination of styrene (STY)/butyl acrylate (BA) reactivity ratios synthesized by solution copolymerization method. The monomer reactivity ratios as well as the 95 % individual confidence limits were determined by application of conventional linear methods like Finemann–Ross, Ezrielev–Brokhina–Roskin, Joshi–Joshi, Kelen–Tudos, modified Kelen–Tudos, extended Kelen–Tudos and Mao–Huglin. The estimation process was performed by applying techniques based on ordinary least square (OLS) and GLS approaches and the results were compared. The results showed a fairly good agreement between the experimental and calculated copolymer compositions. The model was then successfully validated through handling regression models with error terms that are heteroskedastic or autocorrelation, or both and clearly showed that the model was able to predict the reactivity ratios by accounting response error structure. Based on the copolymer compositions determined by ¹H NMR, the reactivity ratios of STY and BA were found to be 0.886634 and 0.216369, respectively, by Mao–Huglin method through the GLS approach, and this new estimation method shows the best linear estimations for the monomer reactivity ratios. The present paper shows a new estimation integral approach for determining the monomer reactivity ratios by different conventional linear methods at low and high conversions in EViews software and the calculated values are discussed in terms of regression models.     

Field Enhancement in Metamaterial Split Ring Resonator Aperture Nano-Antenna with Spherical Nano-Particle Arrangement

Silicon - In this paper, we present a split ring resonator (SRR) for a nano-aperture antenna for biomedical and spectroscopy applications. We have shown that while the graphene coat layer is...     

Design and analysis of a high quality factor multipath spiral inductor

Microsystem Technologies - Recently high quality factor and small-occupying-area inductors are prerequisite for wireless communication products such as mobile phones and wireless network, low cost...     

Effect of pseudopotential choice on the calculated electron and phonon band structures of palladium hydride and its vacancy defect phases

Density functional theory is increasingly used to predict and understand the properties of hydrogen storage materials. Many such calculations have been performed for various real and hypothetical palladium hydrides, yet despite excellent agreement on electron band structures, significant disparities persist in relation to phonon band structures and critical matters such as dynamic stability of alternative structures. Some disparities may arise because of differing computation approaches between researchers. Therefore in this work a systematic approach was followed to compare calculated electron and phonon band structures for four palladium hydrides: PdH and Pd₃VacH₄ (the superabundant vacancy phase) assuming that octahedral (oct) or tetrahedral (tet) lattice interstices are occupied by H, with six commonly used calculation schemes based on the local density approximation and the generalised gradient approximation, within the harmonic approximation. Of the twenty-four combinations tested, seven are new to the literature. Excellent agreement was found between the calculation schemes for the electron band structures of all four crystal structures. The position regarding phonons is much less satisfactory, however, and highlights the sensitivity of phonon properties to the calculated lattice constants. None of the calculation schemes could reproduce the measured phonon energy gap of PdH(oct) and it is necessary to include anharmonicity of the H potential to obtain realistic results. The calculated lattice constants of PdH(tet) were larger than any observed in experiments, although the structure is dynamically stable. All six calculation schemes predicted dynamic instability for Pd₃VacH₄(oct), although the calculated lattice constant agreed with the estimated zero-temperature experimental value. This structure requires new calculations accounting for anharmonicity. The calculated lattice constant for Pd₃VacH₄(tet) was larger than any experimental value, so this alternative, while dynamically stable, is certainly not observed.     

Fabrication,Application and Mathematical Modeling of a new Diamine/Trimesoyl Chloride Reverse Osmosis Composite Membrane for Copper Sulfate Desalination from Wastewaters

Excessive amounts of copper ions in the water sources can be harmful to mammals and especially humans. In this study, a new RO composite membrane is fabricated via the interfacial polymerization (IP) reaction of trimesoyl chloride (TMC), piperazine (PZ) and 3,5-diaminobenzoicacid (DABA). The IP reaction was conducted on a polysulfone (PS) layer which acts as a mounting layer for the separation TMC-DABA-PZ layer. The IP reaction time, TMC concentration and transmembrane pressure were the selected study variables. For IP reaction times around 10 s the rejection and flux were equal to 79% and 21.3 L.m^?2.h^?1, respectively, while increasing the IP reaction time to 40 s elevates the rejection and flux to 92% and 27.7 L.m^?2.h^?1, respectively. TMC concentrations around 0.05% w/w demonstrated rejection and flux equal to 88% and 14.3 L.m^?2.h^?1, respectively, while its elevation to 0.2% w/w, increased the rejection and flux to 90% and 17.5 L.m^?2.h^?1, respectively. As with the transmembrane pressure, the optimum pressure was 20 bars, in which the rejection and flux were 95% and 24.07 L.m^?2.h^?1, respectively. Membrane morphology tests are also supporting evidence for these results. The mathematical modeling has also shown that the relation between the concentration, rejection and flux parameters match the resultant data from the conducted experiments. Since both the rejection and the flux of the fabricated membranes have shown great results, such membranes can be used for wastewater treatment at industrial scales.     

Lipid Nanotechnology

Nanotechnology is a multidisciplinary field that covers a vast and diverse array of devices and machines derived from engineering, physics, materials science, chemistry and biology. These devices have found applications in biomedical sciences, such as targeted drug delivery, bio-imaging, sensing and diagnosis of pathologies at early stages. In these applications, nano-devices typically interface with the plasma membrane of cells. On the other hand, naturally occurring nanostructures in biology have been a source of inspiration for new nanotechnological designs and hybrid nanostructures made of biological and non-biological, organic and inorganic building blocks. Lipids, with their amphiphilicity, diversity of head and tail chemistry, and antifouling properties that block nonspecific binding to lipid-coated surfaces, provide a powerful toolbox for nanotechnology. This review discusses the progress in the emerging field of lipid nanotechnology.