In this study, the effect of clamping pressure on the performance of a proton exchange membrane fuel cell (PEMFC) is investigated for three different widths of channel. The deformation of gas ...diffusion layer (GDL) due to clamping pressure is modeled using a finite element method, and the results are applied as inputs to a CFD model. The CFD analysis is based on finite volume method in non-isothermal condition. Also, a comparison is made between three cases to identify the geometry that has the best performance. The distribution of temperature, current density and mole fraction of oxygen are investigated for the geometry with best performance. The results reveal that by decreasing the width of channel, the performance of PEMFC improves due to increase of flow velocity. Also, it is found that intrusion of GDL into the gas flow channel due to assembly pressure deteriorates the PEMFC performance, while decrease of GDL thickness and GDL porosity have smaller effects. It is shown that assembly pressure has a minor effect on temperature profile in the membrane-catalyst interface at cathode side. Also, assembly pressure has a significant effect on ohmic and concentration losses of PEMFC at high current densities.
•The effect of clamping pressure on the performance of PEMFC is investigated.•Numerical simulation is performed base on non-isothermal condition.•Intrusion of GDL into the gas flow channel deteriorates the performance considerably.
In this paper, the electrochemical performance and temperature distribution of a polymer electrolyte membrane water electrolyzer (PEMWE) are studied using a numerical model. The effect of three ...important parameters including operating pressure, operating temperature, and thickness of the membrane on the thermal and electrochemical performance of the electrolyzer are investigated. The results of numerical modeling are verified against experimental data. Higher temperature is observed over the anode because the exothermic process at the anode is dominant in PEMWE. By increasing the operating temperature and decreasing the operating pressure, the temperature distribution is more uniform and the performance of the electrolyzer improves. By increasing temperature from 333 K to 353 K, the mean temperature difference decreases by 4.5%. In addition, by increasing membrane thickness from 127μm to 254μm, the mean temperature difference of the electrolyzer cell increases by 0.18 K, and the voltage of the electrolyzer increases by about 3.63%.
•The thermal and electrochemical performance of a PEM water electrolyzer is explored.•The maximum temperature of PEMWE occurs on the anode electrode half-cell.•The working conditions to achieve a more uniform temperature distribution are explored.•Increase of the working temperature by 50 K leads to almost 4% lower electrolyzer voltage.
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•A new rapid, green and eco-friendly method is developed for synthesis carbon dots.•The CDs have excellent stability in different conditions and are non-toxic.•The CDs are excellent ...candidate for cell imaging for imaging of cancer cells.•They can use as a sensitive sensor for detection drug at low concentration in blood.
For the first time, a novel and green strategy have been successfully established to synthesize carbon dots from saffron. In this synthesis, a simple method based on hydrothermal treatment was used to synthesis carbon dots with a quantum yield of 23.6%. The as-synthesized carbon dots exhibited many advantages including high fluorescence intensity, water solubility, stability, non-toxic, eco-friendly and importantly using in sensing drugs and cell imaging. Also, the carbon dots were used to assay prilocaine based on quenching assay, without any labeling or using chemical reagents. The influence of several experimental parameters affecting the optical signal, were studied. Under the optimal conditions, prilocaine was measured in a linear range of 2.3–400nmolL−1 (0.5–90ngmL−1). The sensor enables to detect prilocaine as low as 1.8nmolL−1. Finally, the carbon dots were applied for cell imaging of bone marrow cells and Olfactory mucosa cells from rats to illustrate their potential in various applications, with satisfactory results.
In this paper, we investigate the granularity in the free layer of the magnetic tunnel junctions (MTJ) and its potential to function as a reservoir for reservoir computing where grains act as ...oscillatory neurons while the device is in the vortex state. The input of the reservoir is applied in the form of a magnetic field which can pin the vortex core into different grains of the device in the magnetic vortex state. The oscillation frequency and MTJ resistance vary across different grains in a non-linear fashion making them great candidates to be served as the reservoir's outputs for classification objectives. Hence, we propose an experimentally validated area-efficient single granular vortex spin-torque nano oscillator (GV-STNO) device in which pinning sites work as random reservoirs that can emulate neuronal functions. We harness the nonlinear oscillation frequency and resistance exhibited by the vortex core granular pinning of the GV-STNO reservoir computing system to demonstrate waveform classification.
Anti-quorum sensing (QS) or quorum quenching (QQ) is known as a new anti-bacterial strategy to combat bacterial infection. One of the best candidates for this strategy is a natural plant or ...traditional herbal medicine. This review aimed to summarize and introduce Iranian medicinal plants with anti-QS properties. Biomedical databases (PubMed, Scopus, Google Scholar and Web of sciences) were investigated to retrieve all related manuscripts published in English and Persian. Out of 65 documents, 47 papers were published during 2010–2020. We categorized and summarized 19 papers that particularly presented the anti-QS activity of Iranian medicinal plants. Based on our results, different studies have been completed on the QQ effects of medicinal plants. We identified 106 plant species with different properties in medicine that have been evaluated for anti-QS activities in Iran. The QQ effects of herbal extracts were identified through different in vitro examinations on biosensor and clinical bacterial strains. Only 35 medicinal plants have shown these effects at sub-MICs. Our review summarizes Iranian medicinal plants with anti-QS properties. Some of these herbal extracts showed anti-QS activity against biosensors, standard and clinical bacterial strains. This result is very important because QS systems can be considered as a new target for the development of new remedial strategies and it is a good opportunity to perform QQ studies to effectively combat bacterial infections in the future.
Today an alternative approach to control bacterial infections is the use of natural and traditional plant compounds to interfere with their quorum-sensing (QS) systems. In this study, antibacterial ...and anti-QS sensing activity of Syzygium aromaticum, Dionysia revoluta Boiss. and Eucalyptus camaldulensis Dehnh. were evaluated. These plants are local to the Middle East region and have since ancient times been used for their antibacterial activity. Plant compounds were extracted with n-hexane, methanol and 96% ethanol mixed solvent. Antibacterial activity of this herbal extracts against five Gram-negative and Gram-positive bacteria were assessed. The effective sub–minimum inhibitory concentration (MIC) of this extract on bacterial QS systems were investigated by a violacein quantification assay in the Chromobacterium violaceum CV026 biosensor strain, inhibition of exogenously QS signal molecules in Aeromonas veronii bv. Sobria strain BC88 and Pseudomonas aeruginosa isolated from a patient with cystic fibrosis in vitro. Results found that Syzygium aromaticum 0.39 to 0.048 mg/mL, Dionysia revoluta Boiss. 3.1 to 0.39 mg/mL and E. camaldulensis 0.78 to 0.097 mg/mL showed anti-QS activities by reducing the violacein formation depletion of QS signals produced in A. veronii and P. aeruginosa at sub-MICs. Regarding the anti-QS effects of these herbal extracts, their effective components may be candidates for use in combating bacterial infections at sub-MICs.
In this research, the interaction of isoniazid drug (INH) with the pristine and Ni-doped Gallium nitride nanotubes (GaNNTs) is investigated by using density function theory. The adsorption energy, ...deformation energy, natural bond orbital (NBO), quantum parameters, molecular electrostatic potential (MEP) and thermodynamic parameters of all adsorption models are calculated from optimized structures. The values of adsorption energy, enthalpy and Gibbs free energy of all adsorption models are negative and all adsorption process are favorable in view of thermodynamic points. It is notable that Ni-doped decrease adsorption strength and it is not suitable for INH adsorption on the GaNNTs surface. The MEP, NBO and maximum amount of electronic charge ΔN results demonstrate that the negative potential are localized around adsorption position and the positive potential are localized around INH molecule. The calculated results indicate that the GaNNTs is a good candidate to making absorber and sensor for detecting INH drug.
Medical wastewater is a significant contributor to environmental pollution, posing severe risks to both human health and the environment. To resolve this challenge, the removal of anti-cancer drugs ...from medical wastewater has been considered. This study investigated the removal of doxorubicin, an effective anti-cancer drug, from an aqueous solution using three types of adsorbents: activated carbon, multi-walled carbon nanotube, and montmorillonite. Our findings revealed that carbon nanotubes exhibited superior performance in doxorubicin removal from water compared to the other two adsorbents. Specifically, the maximum adsorption capacity of doxorubicin with an initial concentration
of 50 mg L–1 on the carbon nanotube reached 500 mg g–1. In addition, surface modification of the adsorbents with acid resulted in a 15 % and 41 % increase in adsorption capacity, and an 85 % and 67 % reduction in equilibrium time for carbon nanotube and
montmorillonite, respectively. The increasing pH proved to enhance the adsorption efficiency of carbon nanotubes and activated carbon, with the best performance achieved at solution pH of 10 and 8 for MWCNTs and AC, respectively.
Despite known toxic properties of phenol and its derivatives, their man-caused release into nature continues. Their importance as building blocks in polymers, pesticides, pharmaceuticals and other ...industrial chemicals remains a barrier for reducing their introduction into ecosystems. Hence, a considerable effort has been devoted to these organic contaminates removal from water sources. In the present work, we have employed functionalized (5, 5) carbon nanotubes (f-CNTs) for adsorption and remidiation of phenol pollutant from water. Several binding sites (incloding hydroxyl and phenyl groups) were considered due to their ability in π-π stacking and H-bonding interactions with phenol. The adsorption modes and energies of both water and phenol to these sites are evaluated using a general dispersion-corrected density functional (DFT-D3) method. We showed that both water and phenol molecules are weakly bound (weak physisorption) to the outer surface of pristine CNT while they can be adsorbed stronger on the functionalized CNTs. It was found that phenol bound stronger to the CNT-OH than water molecule which was due to the existence of simultaneous π-π stacking and H-bonding in the system. Also, we have prepared a brief report about the solvent effect in the adsorption nature of the more stable systems.The results show that the absorption energy sequence for the absorbing/carbon nanotube complexes in the aqueous phase is similar to the calculated absorption energy for in the gas phase, but adsorption decreased in the aqueous phase. We have also provided a succinct report about the reactivity, energy gap and polarity of the considered systems for all systems. For comparison, we evaluated the adsorption behavior for zigzag OH-CNT (8, 0).The calculation reveal that difference of the binding energy of phenol and water molecules on a zigzag is alike to the armchair CNT system. The phenol adsorption properties onto CNT-OH system in periodic and cluster SWCNT have compared and we were found that the results predicted by the CNT saturated with hydrogen can be comparable to periodic SWCNT. Furthermore, our first-principles calculations demonstrated the importance of dispersion corrections based on weak intermolecular interactions in designing absorbents. Our study offers molecular level understanding of the interactions between water/phenol molecule and CNTs surface and may be informative for toxicity agent adsorption and remediation from environment.
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•Full geometries optimization with DFT was performed for interacting phenol/H2O with CNT/functionalized-CNT.•Phenol/H2O adsorption on pristine SWCNT is really weak.•Functionalization of CNT by OH group increases phenol adsorption significantly.•Long-range dispersion correction plays an important role in systems under consideration.
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