Fullerene: biomedical engineers get to revisit an old friend

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The experimental and numerical impacts of geometrical parameters of conical shock tube on the function,maximum pressure and generative impulses to expose equivalent mass and behavioral equation

One of the methods to investigate the phenomenon of explosion underwater and its impact on the structures is to use the conical shock tube. These tubes produce a lot of pressure using a tiny explosive charge. In this essay, the geometry of the established/manufactured explosive shock tube is demonstrated first and the results of the experiments operating the tube is presented. Then, the explosion of a given amount of explosive charge in the conical shock tube is studied by benefiting the LS‐DYNA code. The numerical simulation is done by Lagrange‐Oiler selected multi‐materials solutions. To ensure the authenticity of the selected method in the software, the results of the stimulated model is compared with the experimental outcomes accordingly, after accrediting the accuracy of the results, the stimulating and scrutinizing the effects of geometrical parameters on the function of explosive shock tubes is proceeded. In this research, the effect of the cone head angel on the produced pressure inside the shock tube is analyzed first. Then, the function of shock tubes with different lengths is checked. Moreover, after changing the scale of the explosive charge and studying the outcome, stating the reasons for changes in each parameter and examining the effect of the relation between the explosive proportion and the water volume inside the shock tube, an equation for the equivalent mass for all sock tubes with different angels is exhibited and the existing theoretical relation is revised. Finally, by examining the pressure and impulses changes in different intervals, an equation is presented to anticipate the pressure and impulses in different shock tubes.     

Combined cerium oxide nanocapping and layer-by-layer coating of porous silicon containers for controlled drug release

Local drug release in close vicinity of solid tumors is a promising therapeutic approach in cancer therapy. Implantable drug delivery systems can be designed to achieve controlled and sustained drug release. In this study, ultrathin porous membranes of silicon wafer were employed as compatible drug reservoir models. An anticancer model drug, curcumin (CUR), was successfully loaded into porous silicon containers (8.94?±?0.72% w/w), and then, cerium oxide nanocapping was performed on the open pores for drug protection and release rate prolongation. Next, layer-by-layer surface coating of the drug container with anionic (alginate) and cationic (chitosan) polymers rendered pH-responsivity to the device. The drug release profile was studied using reflectometric interference Fourier transform spectroscopy at different pH conditions. It was determined that faster decomposition of the polymeric layers and subsequent CUR release occur in acidic buffer (pH 5.5) compared to a neutral buffer. Various characterization studies, including dynamic light scattering, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy, contact angle measurement, ultraviolet–visible spectroscopy, and X-ray powder diffraction revealed that our system has the required physicochemical properties to serve as a novel pH-sensitive drug delivery implant for cancer therapy.     

Observation of Small Exchange Bias in Defect Wüstite (Fe0.93O) Nanoparticles

Wüstite nanoparticles have been prepared by mechanochemical processing (MCP), using high-purity hematite (α-Fe₂O₃) and iron (Fe) powders as the raw materials. In order to get a single-phase wüstite, different mole ratios of (Fe/Fe₂O₃) were milled. X-ray diffraction studies of the as-milled powders show that a single-phase wüstite was formed. Using the formula a=4.334?0.478x, for Fe_1?x O, where “a” is the lattice parameter of wüstite, a nonstoichiometric composition of Fe_0.93O was estimated for the wüstite single phase. A mean crystallite size of 13±1 nm was calculated for the single phase wüstite, using Scherrer’s formula. The morphology of the powders was also checked by TEM. The room-temperature Mössbauer spectra of the samples supported the presence of Fe³⁺ in octahedral sites of wüstite phase, which is a sign of its nonstoichiometry. Hysteresis loops of the as-milled powders at 5 K and room temperature have been obtained by SQUID and by VSM systems, respectively. The loops show nonzero coercivity, in contrast to the bulk wüstite. The observed magnetizations can be explained by a model based on the spinel-type defect clusters in nonstoichiometry wüstite. Room temperature magnetic measurements showed that nanosized prepared wüstite ferrimagnetic-like behavior was interpreted according to spinel-like defect clusters. Therefore, small exchange bias effects 20 Oe and 38 Oe were observed in the magnetization curves at room and 5 K temperatures, respectively. According to the Dimitrov model, in the Fe_0.93O nonstoichiometry structure, there are 0.712 molecules of FeO and 0.072 molecules of Fe₃O₄, which the interaction between the antiferromagnetic (FeO) and ferrimagnetic (Fe₃O₄) phases in the Fe_1?x O can be the cause of the observed exchange bias effect in the hysteresis loops.     

Preparation,characterization and in vitro anticancer activity of paclitaxel conjugated magnetic nanoparticles

In this study, magnetic nanoparticles (MNPs) coated with L-aspartic acid (F-Asp NPs) were synthesized through a co-precipitation method and conjugated with paclitaxel (PTX) (F-Asp-PTX NPs) by esterification reaction between the carboxylic acid end groups on MNPs surface and the hydroxyl groups of the PTX and studied its cytotoxic effect in vitro. The successful conjugating of PTX onto the nanoparticles (NPs) was confirmed by X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM) and transmission electron microscopy (TEM) techniques. The results showed that the average size was 46.11?±?7.8 (mean?±?SD (n?=?25)) nm. The cytotoxicity of void of PTX and F-Asp-PTX NPs were compared to each other by MTT assay of the treated MCF-7 cell line. The F-Asp-PTX NPs showed pH-dependent drug release behavior. These studies specify that F-Asp-PTX NPs have a very remarkable anticancer effect, for breast cancer cell line.     

Fabrication of novel ZnO/MnWO4 nanocomposites with p-n heterojunction: Visible-light-induced photocatalysts with substantially improved activity and durability

We report, for the first time, binary ZnO/MnWO₄ nanocomposites with p-n heterojunction fabricated by a simple ultrasonic-calcination route. The phase structure, morphology, and optical along with textural properties were comprehensively characterized. The photocatalytic performance was studied via degradations of rhodamine B, methyl blue and methyl orange (RhB, MB, MO), and fuchsine pollutants under visible-light illumination. The ZnO/MnWO₄ nanocomposites exhibited better photocatalytic performance than their single components and the nanocomposite with 30?wt% MnWO₄ showed the highest activity. Photocatalytic performance of this nanocomposite is 22.5, 17.7, 26.8, and 23.9 times higher than that of the ZnO sample in degradations of RhB, MB, MO, and fuchsine dyes, respectively. The improved photocatalytic performance was ascribed to the formation of p-n heterojunction between ZnO and MnWO₄ with high charge separation efficiency as well as strong visible-light absorption ability. The possible mechanism for the improved photocatalytic performance was proposed. This study revealed that the novel ZnO/MnWO₄p-n heterojunction can act as a promising visible-light-active photocatalyst for environmental applications.     

Particle Dispersion Dependency on the Entrance Position in Bidirectional Flow

This article presents a process of numerically predicting and experimentally verifying the dispersion quality and penetration level of fuel particles entering and moving in various directions relative to vortex engine walls. If the length scale of particles considered in this study is not comparable to the chamber length and, furthermore, the density is ignored, the effect of the particle on the flow field can be neglected and a one-way solution will be viable for the problem. The solutions in each case are carried out to estimate the particle trajectory and parameters affecting it. The governing equations are converted to a set of nonlinear, coupled, ordinary differential equations (ODEs) of second order, and solved by a numerical scheme. The results indicate that a high centrifugal force pushes the particles toward the sidewall. This propelling force becomes more eminent when the particles approach the chamber center-position. Moreover, the results reveal that the best injection configuration in the vortex engine arrangement is simply not the head side arrangement; the sidewall, and end side composition arrangement of the injection demonstrates to provide the best desired outcomes.     

Investigating the flow structures in semi-cylindrical bubbling fluidized bed using pressure fluctuation signals

Hydrodynamic characteristics of a gas-solid semi-cylindrical fluidized bed was experimentally investigated and compared with that of a cylindrical bed by analysis of pressure fluctuations. Pressure fluctuations were analyzed in time and frequency domains using standard deviation, power spectral density function and discrete wavelet transform methods. Experiments were carried out in two semi-cylindrical and cylindrical fluidized beds of 14?cm in diameter each, operating in the bubbling fluidization regime at ambient pressure and temperature. Both beds were filled with glass beads of various sizes (120, 290 and 450?µm). The superficial gas velocity was varied in the range of 0.2–0.8?m/s. Results showed that although the minimum fluidization velocity is influenced by the particle size, it is not affected by the geometry of the bed. It was shown that the hydrodynamics of both beds are very similar and the difference is negligible. Number of large bubbles is slightly larger in the semi-cylindrical bed as compared with the cylindrical bed. Also, increase in the particle size and superficial gas velocity result in a greater difference between the number of large bubbles in both beds and the number of large bubbles in the semi-cylindrical bed increases slightly faster than in the cylindrical bed.     

RNA secondary structured logic gates for profiling the microRNA cancer biomarkers

Deregulation of microRNAs expression is symptomatic of cancer disease and occurs before the awareness of cancer signs. Early detection of cancer disease can improve or drop the disease entirely. DNA computing is an emerging field of detecting microRNAs based on toehold‐mediated strand displacement reactions, which is a more efficient method than the commonly used method like real‐time PCR. Accuracy and cost of diagnostic applications are essential criteria that are achieved by using the DNA logic gates based on the DNA computing method. In this study, the authors proposed the multi‐input liver cancer biosensor with the RNA secondary structure motifs as the computational module and two approaches are suggested.Inspec keywords: cancer, biocomputing, biochemistry, DNA, RNA, biosensors, logic gates, liver, macromolecules, genetics, molecular biophysics, diseasesOther keywords: RNA secondary structured logic gates, microRNA cancer biomarkers, microRNAs expression, cancer disease, cancer signs, detecting microRNAs, toehold‐mediated strand displacement reactions, DNA logic gates, DNA computing method, multiinput liver cancer biosensor, RNA secondary structure motifs