Barium hexaferrite nanoparticles: morphology-controlled preparation,characterization and investigation of magnetic and photocatalytic properties

In this paper, barium hexaferrite (BaFe₁₂O₁₉) nanoparticles have been successfully synthesized via a simple co-precipitation route. Six chelating agents such as three amino acids (proline, alanine, aspartic acid) and three surfactants (SDBS, PVP, and EDTA) were used. The result showed that the amino acids decrease the particle size and the best result was observed for alanine. Besides, the photocatalyst activity of as-prepared BaFe₁₂O₁₉ nanoparticles was evaluated by degradation of methyl orange under visible light irradiation (λ?>?400 nm). The degradation rates of the methyl orange were measured to be as high as 95% in 200 min. The nanoparticles were also characterized by several techniques including FT-IR, XRD, SEM, and VSM. The VSM measurement showed a saturation magnetization value (Ms) of 30 emu/g.     

Probing the in vitro binding mechanism between human serum albumin and La2 O2 CO3 nanoparticles

The interaction of La₂ O₂ CO₃ nanoparticles (La NPs) with human serum albumin (HSA) has been studied. Analysis of the fluorescence quenching data of HSA using Stern–Volmer method showed that La NPs quenched HSA fluorescence in static quenching mode. Thermodynamic analysis indicated that hydrogen bonds and Van der Waals interactions play a major role for HSA–La NPs associations. Fluorescent displacement measurements confirmed that the primary binding site of La NPs was mainly located within site I (subdomain IIA) of HSA. The binding distance was calculated by using Forster resonance energy transfer theory. Also, the results of Fourier‐transform infrared spectroscopy, circular dichroism, three‐dimensional fluorescence and UV–visible measurements indicated that the binding of above La NPs to HSA may induce conformational and micro‐environmental changes of protein. This study suggested that the conformational change of HSA was at secondary structure of it and the biological activity of this protein was changed in the present of La NPs.Inspec keywords: proteins, molecular biophysics, molecular configurations, nanoparticles, lanthanum compounds, fluorescence, radiation quenching, thermal analysis, biothermics, biochemistry, hydrogen bonds, van der Waals forces, Fourier transform infrared spectra, circular dichroism, visible spectra, ultraviolet spectra, nanobiotechnologyOther keywords: in vitro binding mechanism, human serum albumin, La₂ O₂ CO₃ nanoparticles, Stern‐Volmer method, La NPs quenched HSA fluorescence, static quenching mode, thermodynamic analysis, hydrogen bonds, Van der Waals interactions, HSA‐La NPs associations, fluorescent displacement measurements, primary binding site, subdomain IIA, binding distance, Forster resonance energy transfer theory, Fourier‐transform infrared spectroscopy, circular dichroism, three‐dimensional fluorescence, UV‐visible measurements, conformational changes, microenvironmental changes, protein, secondary structure, La₂ O₂ CO₃      

Hydroelastic response suppression of a flexural circular bottom plate resting on Pasternak foundation

Coupled hydroelastic response control of a thin circular plate supported on a two-parameter elastic foundation and in full contact with an overlaying inviscid sloshing liquid is considered. The response suppression is accomplished by a free-floating smart piezo-sandwich circular panel based on an auto-tuned PID feedback control loop. Durbin’s numerical Laplace transform inversion scheme is selected to calculate the key uncontrolled/controlled hydroelastic response parameters for different types of transient disturbances. The external excitations include: a central pulse load on the bottom plate, a distributed impulsive load on the floating panel, and low-/high-frequency seismic base excitations. The effects of passive/smart floating panel, overlaying liquid height, and excitation type on the key hydroelastic field variables are examined. It is found that the passive floating panel has nearly no effect on the suppression of the field variables associated with the bottom plate, while the overall effectiveness of the active floating panel control configuration is demonstrated. Limiting situations are considered and the validity of model is confirmed through comparisons with the available data in addition to the results obtained by commercial FEM software.     

Making a wearable supercapacitor based on highly porous 3D nitrogen-doped graphene

In this paper, based on the hydrothermal method and using a non-toxic organic molecule, as a spacer (and nitrogen source), we synthesized a highly conductive and porous 3D graphene. Then, graphene is used as an electrode material to make a supercapacitor on the surface of activated carbon cloth electrode. The graphene is characterized by different methods, such as Fourier-transform infrared spectroscopy, thermogravimetric analysis, Raman spectroscopy, X-ray diffraction, energy-dispersive and transmission electron microscopy, energy-dispersive X-Ray spectroscopy, emission scanning electron microscopy, Barrett–Joyner–Halenda, and Brunauer–Emmett–Teller methods. The supercapacitor (2 and 3 electrodes) is studied by different electrochemical techniques, such as cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge. The 3-electrode system shows a specific capacity 101 F g^? 1 at the current density of 1.7 A g^? 1 (or 0.5 mA cm^? 2). The 2-electrode system (symmetric capacitor) has a power density of about 8000 W kg^? 1 and a maximum energy density of 12.85 Wh kg^? 1.

     

Variational approach development in analysis of matrix cracking and induced delamination of cross-ply composite laminates subjected to in-plane shear loading

Matrix microcracking and induced delamination propagating from the edge of microcracks in cross-ply composite laminates with [0_n/90_m]_s and [90_m/0_n]_s layups under in-plane static shear loading are investigated. An admissible stress field, which satisfies all of equilibrium equations, boundary conditions, and continuity of interfaces, is approximated. Then using the principle of the minimum complementary energy, the stress state is obtained from calculations of variation. The calculated stress state gives the stiffness reduction and the total strain energy of the laminated composite structure. Finally, the strain energy release rate of a general cross-ply laminate due to initiation and propagation of matrix cracking and induced delamination can be deduced. Results of the developed approach are in good agreement with experimental observations and finite element analyses, which confirms its accuracy.     

A focus on the features of polyaniline nanofibres prepared via developing the single crystals of their block copolymers with poly(ethylene glycol)

Poly(ethylene glycol) (PEG)–polyaniline (PANI) diblock and triblock copolymers were synthesized via copolymerization of aniline with amine-terminated PEG by interfacial polymerization using sulphuric acid as dopant and ammonium peroxydisulfate (APS) as well as potassium hydrogen diiodate (PHD) as oxidants. The PHD-based synthesized PANI nanorods possessed longer lengths, narrower diameter distribution and higher conductivity. The electroactivity of synthesized copolymers was characterized using ultraviolet–visible (UV–Vis) spectrometry, cyclic voltammetry (CV) and resistivity measurement. Even in the presence of dielectric PEG blocks, the synthesized block copolymers had a conductivity around 3 S \(\hbox {cm}^{-1}\). In a further step, the solution-grown single crystals were prepared to investigate the general features of grafted PANI nanorods using small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Based on AFM and SAXS analyses, the bimodal gel permeation chromatography (GPC) traces obtained from the block copolymers were originated from the diameter distribution of nanofibres, not from the dispersity of their lengths and molecular weights.     

Effect of poly‐glutamate on uptake efficiency and cytotoxicity of cell penetrating peptides

Cell penetrating peptides (CPPs) were developed as vehicles for efficient delivery of various molecules. An ideal CPP‐peptide should not display any toxicity against cancer cells as well as healthy cells and efficiently enter into the cell. Because of the cationic nature and the intrinsic vector capabilities, these peptides can cause cytotoxicity. One of the possible reasons for toxicity of CPPs is direct translocation and consequently, pore formation on the plasma membrane. In this study it was demonstrated that interaction of poly‐glutamate with CPP considerably reduced their cytotoxicity in A549 cell. This strategy could be useful for efficient drug delivery mediated by CPP.Inspec keywords: cellular biophysics, polymers, drug delivery systems, biomedical materials, toxicology, molecular biophysicsOther keywords: drug delivery, A549 cell, plasma membrane, pore formation, cancer cells, poly‐glutamate, cytotoxicity, uptake efficiency, cell penetrating peptides     

An Energy-Efficient Dynamic Resource Management Approach Based on Clustering and Meta-Heuristic Algorithms in Cloud Computing IaaS Platforms

Wireless Personal Communications - Cloud computing as an emerging technology, has revolutionized the information technology industry by elastic on-demand provisioning and De-provisioning of...     

The effects of multiple firefighting activities on information processing and work performance in a smoke‐diving room: An intervention study

Firefighters perform various tasks during firefighting operations under unknown and unpredictable conditions. The present study investigated the impact of firefighting activities and cooling tactics on information processing and work performance. Firefighters performed typical firefighting tasks in the four experimental conditions, namely i) no cooling device (NC), ii) cooling gel (CG), iii) cool vest (CV), and iv) cooling gel and cool vest (CG + CV). The measurement of information processing, Paced Auditory Serial Addition Test (PASAT) scores decreased significantly after the firefighting activities in the four conditions, relative to baseline. The results revealed no significant difference in PASAT scores among the four conditions. However, the performance time (PT) was significantly shorter for the CV and CG + CV compared to the NC and CG conditions. The findings confirmed that the firefighting activities have a detrimental effect on information processing. The CG + CV and CV were more effective than CG and NC in improving PT during firefighting. However, the cooling strategies have a negligible effect on improving information processing performance.     

Quarter car active suspension system: Minimum time controller design using singular perturbation method

Suspension systems have been widely applied to vehicles. Every vehicle moving on the randomly profiled road is exposed to vibration and shocks which is harmful both for the passengers in terms of comfort and for the durability of the vehicle itself. From this point of view, it is important to reset to zero displacement, velocity and acceleration of car in minimum time. So, this paper proposes a new minimum time controller based on bang-bang control for the quarter car active suspension systems. First by using singular perturbation method the original suspension system is decomposed into two fast and slow singular subsystems in theory, and then by Pontryagain’s Minimum Principle (PMP) and switching functions, the controller is designed for each subsystem and finally the optimal final time is obtained as maximum optimal time concluded of two subsystems. By using a degree of stability technique with two parameters (instead of four parameters), the optimal time is more reduced and leads to great simplifications in practical implementation. The performance of the controller is compared with the Sub optimal Linear Quadratic Regulator (SLQR) controller using two types of road profiles (step and bump) implemented in MATLAB/Simulink. Test results demonstrate the proposed controller is very more effective and simpler in eliminating fluctuations in suspension systems that finally provide the passengers comfort.