Efficient X-ray CT-based numerical computations of structural and mass transport properties of nickel foam-based GDLs for PEFCs

Nickel foams are excellent candidate materials for gas diffusion layers (GDLs) for polymer electrolyte fuel cells (PEFCs) and this is due to their superior structural and transport properties. A highly computationally-efficient framework has been developed to not only estimate the key structural and mass transport properties but also to examine the multi-dimensional uniformity and/or the isotropy of these properties. Specifically, multiple two-dimensional X-ray CT images and/or numerical models have been used to computationally determine the porosity, the tortuosity, the pore size distribution, the ligament thickness, the specific surface area, the gas permeability and the effective diffusivity of a typical nickel foam sample. The results show that, compared to the conventionally used carbon substrate, the nickel foam sample demonstrate a high degree of uniformity and isotropy and that it has superior structural and mass transport properties, thus underpinning its candidacy as a GDL material for PEFCs. All the computationally-estimated properties, which were found to be consistent with the corresponding literature data, have been presented and thoroughly discussed

Polymer electrolyte fuel cell operating with nickel foam-based gas diffusion layers: a numerical investigation

Due to their outstanding structural, transport and electrical characteristics, nickel foams serve as excellent candidate materials for gas diffusion layers (GDLs) in polymer electrolyte fuel cells (PEFCs). In this work, a new three-dimensional PEFC model was developed to explore the local and global fuel cell performance with nickel foam-based GDLs. The fuel cell operating with nickel foam GDLs was shown to have, due to its superior mass and charge transport properties, higher oxygen and water concentration and current density compared to that operating with the conventional carbon fibre-based GDLs. The results show that the pumping power should be taken into account when optimising the dimensions of the flow channels and as such the net power density must be the criterion for optimisation. The optimal dimensions of the flow channels for the fuel cell operating with nickel foam based GDLs were found to be 0.25 mm for the channel height and 1 mm for the channel width; the maximum net power density with these dimensions was around 0.95 W/cm2 which is two times higher than that operating with carbon fibre based GDLs. All the results have been presented and critically discussed

X-ray CT-based numerical investigation of nickel foam-based GDLs under compression

Nickel foams feature superior structural and transport characteristics and are therefore strong candidates to be used as gas diffusion layers (GDLs) in polymer electrolyte fuel cells (PEFCs). In this work, the impact of compression on the key structural and transport properties has been investigated, including employing a specially designed compression apparatus and X-ray computed tomography. Namely, 20 equally spaced two-dimensional CT based images and numerical models have been used/developed to investigate the sensitivity of the key properties of nickel foams (porosity, tortuosity, pore size, ligament thickness, specific surface area, gas permeability and effective diffusivity) to realistic compressions normally experienced in PEFCs. Wherever applicable, the anisotropy in the property has been investigated. One of the notable findings is that, unlike porosity and ligament thickness, the mean pore size was found to decrease significantly with compression. The mean pore size is around 175 μm for uncompressed nickel foam and it decreased to around 110 μm for a 20% compression ratio and to around 70 μm for a 40% compression ratio. Further, unlike the effective diffusivity, the gas permeability was shown to be highly anisotropic with compression; this fact is of particular importance for PEFC modelling where the properties of GDLs are often assumed isotropic. All the computationally estimated properties have been presented, validated and discussed

Olive leave extracts and components as an innovative approach for cancer therapy

Olea europaea (Olive tree) bears the olive fruit, which belongs to the Oleaceae family, grows mainly in the Mediterranean region, and is widely consumed and studied. Recent studies have shown that extracts (OLE) from olive leaves have potent antioxidant and anti-cancer properties. The bioactive components in OLE enable the development of innovative approaches to cancer treatment. These components can have a suppressive effect on various cellular signaling pathways associated with the cancer process and increase the effectiveness and safety of chemotherapy agents targeting multiple signaling pathways in cancer treatment. However, phenolic compounds combined with chemotherapy drugs attract attention in creating new, more effective therapeutic approaches to be used in the treatment of aggressive cancers. Bioactive components have low solubility in water due to their lipophilic structure, and their therapeutic effectiveness is limited by rapid and widespread metabolism, poor systemic absorption, and bioavailability. For this reason, although bioactive components have demonstrated significant anti-cancer and treatment resistance effectiveness in pre-clinical studies, these components cannot demonstrate the expected effect in in-vivo applications due to the mentioned pharmaceutical incompatibilities. Recent studies show that it is possible to maximize therapeutic effects by encapsulating bioactive components within living systems through nanodrug delivery systems. Nanocarriers, with controlled and long-term release, enable biological substances to penetrate further into the target organs and reach the desired daily concentration, significantly increasing the molecules' effectiveness. In particular, local drug delivery creates an alternative treatment option and ensures the continuous release of the active compound at the desired site of action. To date, nanoparticles (NP) and nanofibers as nanocarrier systems have been used to develop cancer treatment strategies. NPs are considered a highly effective approach for intravenous delivery of flavonoids with good encapsulation potential of drugs or bioactive compounds and reduced toxicity. However, these carrier systems have some disadvantages, such as rapid burst release, drug leakage, limitations related to stability and shelf life, inability to provide continuous or controlled drug release, and multiple drug releases. Nanofibers produced by electrospinning are nanoscale biomaterials with a large specific surface area, high porosity, minimal barrier to mass transfer, controllable morphology, and good mechanical resistance. Nanofibers can be produced in various configurations, including monolayer, multilayer, core-shell, ribbon, network, and porous well. The problem of rapid dissolution of active compounds from nanofibers by burst release is overcome by core-shell electrospinning. Due to their biocompatibility and biodegradability, nanocarrier systems have become the focus of particular attention by researchers in drug delivery, tissue engineering, and cancer. Nanocarrier systems increase the drug's performance by drug accumulation on the tumor site, adjustability of the required dosage, and reduction of the side effects of the drug on nontarget tissues. As a result, this section examines the potential of bioactive compounds found in OLE, which are loaded into nanocarrier systems today, to create new, more effective treatment strategies with fewer side effects in cancer cells. This approach can potentially set new standards in cancer treatment and provide more effective and safe treatment options for cancer patients

The structural studies and optical characteristics of phase-segregated Ir-doped LuFeO3-? films

In this work, we carefully examined how Ir substitution into Fe sites can change the band of the LuFeO3 (LFO) material. LFO and Ir-doped LFO (LuFe1-xIrxO3 or LFIO for short, where x = 0.05 and 0.10) thin films were synthesized by utilizing magnetron sputtering techniques. The films were grown on silicon and indium tin oxide (ITO) substrates at 500 degrees C. The crystallographic orientation of the films was examined using X-ray diffraction (XRD) analysis. The crystallographic orientation of the thin films was examined using an X-ray diffractometer (XRD). For surface topography research, atomic force microscopy (AFM) was employed. To look for the recombination of photogenerated electron-hole pairs in the materials under investigation, photoluminescence (PL) spectroscopy was used. Raman spectroscopy is then utilized to gather data on crystal symmetry as well as disorders and defects in the oxide materials. It was demonstrated that the LFO band gap was altered from 2.35 to 2.72 eV by Ir substitution into Fe sites. Moreover, diffuse reflectance spectroscopy (DRS) was used to analyze conductivity, real and imaginary components of the dielectric constant, refractive index (n), extinction coefficient (k), and reflectance percentage.Scientific and Technological Research Council of Turkey (TUBITAK) [116F025]; MEYS CR [LM 2018110]; Istanbul Medeniyet University Science and Advanced Technology Research Center; Istanbul Medeniyet University Science and Advanced Technology Research Center (IMU-BILTAM)This work was supported by The Scientific and Technological Research Council of Turkey (TUBITAK) through Grant No: 116F025. We acknowledge the CEITEC Nano Research Infrastructure supported by MEYS CR (LM 2018110 and Istanbul Medeniyet University Science and Advanced Technology Research Center (IMU-BILTAM)

Handlebar trauma causing small bowel hernia with jejunal perforation

Abstract Not Availabl