Technical feasibility of a proton battery with an activated carbon electrode

The technical feasibility of a small-scale ‘proton battery’ with a carbon-based electrode is demonstrated for the first time. The proton battery is one among many potential contributors towards meeting the gargantuan demand for electrical energy storage that will arise with the global shift to zero greenhouse emission, but inherently variable, renewable energy sources. Essentially a proton battery is a reversible PEM fuel cell with an integrated solid-state electrode for storing hydrogen in atomic form, rather than as molecular gaseous hydrogen in an external cylinder. It is thus a hybrid between a hydrogen-fuel-cell and battery-based system, combining advantages of both system types. In principle a proton battery can have a roundtrip energy efficiency comparable to a lithium ion battery. The experimental results reported here show that a small proton battery (active area 5.5 cm²) with a porous activated carbon electrode made from phenolic resin and 10 wt% PTFE binder was able to store in electrolysis (charge) mode very nearly 1 wt% hydrogen, and release on discharge 0.8 wt% in fuel cell (electricity supply) mode. A significant design innovation is the use of a small volume of liquid acid within the porous electrode to conduct protons (as hydronium) to and from the nafion membrane of the reversible cell. Hydrogen gas evolution during charging of the activated carbon electrode was found to be very low until a voltage of around 1.8 V was reached. Future work is being directed towards increasing current densities during charging and discharging, multiple cycle testing, and gaining an improved understanding of the reactions between hydronium and carbon surfaces.     

A review of the current knowledge and challenges of hydrothermal carbonization for biomass conversion

Greenhouse gases emitted from the excessive use of fossil fuels are threatening the environment, and thus alternative resources like biomass are being considered as a replacement. Biomass with high moisture content is better treated by hydrothermal carbonization method than any other process to generate biofuel. Research on this method on a lab scale has progressed recently. However, due to the complex reaction mechanisms and operational barriers, more improvements are required to make it a commercial technology. This paper aims to review the development of hydrothermal carbonization with a focus on the practical aspects of the process. Many references have been reviewed critically to provide a well-structured source for improving this process. After providing information about the biomass structure and general knowledge of hydrothermal carbonization, the challenges faced in attempts to improve the process have been identified as lack of valid kinetic and heat transfer models and insufficient data on continuous and large-scale reactors. Useful and practical suggestions have been presented to tackle all these challenges.     

Chemical composition and antioxidant activity of oil from wild Achillea setacea and A. vermicularis

The objective of this study was to determine and compare the composition of volatile components of two species, A. setacea and A. vermicularis, under the temperate climatic conditions (north of Iran) and to investigate quantification of fatty acids in the oil extracted using gas chromatography-flame ionization detector and to evaluate the antioxidant potential and the phytochemical profile in terms of phenolic acids and flavonoids content of the oils obtained from the plants. Gas chromatography-mass spectrometry analysis of the essential oils showed that the major compounds of A. setacea were nerolidol (20%) and α-cubebene (14%), while in A. vermicularis were camphor (15%) and borneol (13%). Oil analysis revealed that the major components were palmitic and myristic acids. Chromatographic separation of their phenolic compounds (high-performance liquid chromatography) demonstrated that sinapic, gallic, caffeic, vanillic, syringic, and ferulic acids were present in the two oils of the plants, but in different amounts. These results confirmed A. setacea and A. vermicularis as important sources of bioactive metabolites.     

Phenolic composition and comparison of antioxidant activity of alcoholic extracts of Peppermint (Mentha piperita)

Peppermint (Mentha piperita) has long been regarded as a food and medicinal plant. At the present work, the antioxidant activity of the methanol, ethanol and methanol/ethanol (1:1) extracts of leaf fraction through various in vitro models was investigated in Iranian peppermints for the first time. Total phenol, flavonoid and anthocyanin contents were also determined. Our results showed the alcoholic extracts had different responses with different antioxidant methods. The methanol extract had maximum phenol content (3.57 ± 0.26 g Gallic acid/100 g Peppermint powder) and showed best superoxide radical (47.05 ± 0.85 %) and hydrogen peroxide (91.05 ± 1.50 %) scavenging activities. The methanol/ethanol (1:1) extract had maximum flavonoid (3.33 ± 0.12 g quercetin/100 g Peppermint powder) and anthocyanin contents (1.74 ± 0.21 g/100 g Peppermint powder) and showed best DPPH radical scavenging activity (82.82 ± 2.57 %, IC₅₀ = 10.02 ± 0.63 mg/mL) as well as ferric reducing power (184.22 ± 14.10 μmol/100 g Peppermint powder). The ethanol extract only showed the highest nitric oxide radical scavenging activity (80.13 ± 7.12 %). Chlorogenic acid, rutin, and caffeic acid were found by HPLC analysis of the main phenolic components. These results show, Peppermint alcoholic extracts can be used as a natural antioxidants to reduce oxidative stress in human beings and as a possible food supplement or in pharmaceutical applications.     

Harris hawks optimization: a comprehensive review of recent variants and applications

Neural Computing and Applications - Harris hawks optimizer (HHO) has received widespread attention among researchers in terms of the performance, quality of results, and its acceptable convergence...     

Evaluation of the mechanical properties,in vitro biodegradability and cytocompatibility of natural chitosan/hydroxyapatite/nano-Fe3O4 composite

The main goal of this research was the preparation and evaluation of the mechanical properties, in vitro biodegradability and cytocompatibility, of natural chitosan/hydroxyapatite/nano magnetite (nano-Fe₃O₄) composite. Different ratios of these components were investigated, including chitosan/hydroxyapatite: 4/4 (S1), chitosan/hydroxyapatite: 4/6 (S2), and chitosan/hydroxyapatite: 6/4 (S3). Mechanical properties of fabricated composites were examined using bending and compression tests before immersion, and after 2 and 9 weeks of immersion in the Ringer's solution. Scanning electron microscope (SEM) was employed for observing the bending fracture surface and analyzing the degradation morphology. Human mesenchymal stem cells (hMSC) were also cultured on the samples in order to assess the cytocompatibility. The obtained results revealed that S1 had the highest bending strength before immersion, while S3 had the highest bending strength after 9 weeks immersion. Compressive strength of S2 was greater than that of S1 and S3 not only before immersion, but also after 9 weeks immersion. Although the bio-minerals were deposited on the surface of all samples during the immersion in Ringer's solution, S2 appeared to have the highest quantity of bio-minerals. According to the weight loss percentage (ΔW(%)), the biodegradation resistance of S1 was the lowest. Finally, the cytocompatibility of S1 was greater than that of S2 and S3.     

Evaluation of mechanical and biocompatibility properties of hydroxyapatite/manganese dioxide nanocomposite scaffolds for bone tissue engineering application

The aim of this research was to evaluate the mechanical properties, biocompatibility, and degradation behavior of scaffolds made of pure hydroxyapatite (HA) and HA-modified by MnO₂ for bone tissue engineering applications. HA and MnO₂ were developed using sol-gel and precipitation methods, respectively. The scaffolds properties were characterized using X-ray diffraction (XRD), Fourier transform spectroscopy (FTIR), scanning electron microcopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The interaction of scaffold with cells was assessed using in vitro cell proliferation and alkaline phosphatase (ALP) assays. The obtained results indicate that the HA/MnO₂ scaffolds possess higher compressive strength, toughness, hardness, and density when compared to the pure HA scaffolds. After immersing the scaffold in the SBF solution, more deposited apatite appeared on the HA/MnO₂, which results in the rougher surface on this scaffold compared to the pure HA scaffold. Finally, the in vitro biological analysis using human osteoblast cells reveals that scaffolds are biocompatible with adequate ALP activity.     

Monitoring therapeutic processes using risk-adjusted multivariate Tukey's CUSUM control chart

Using control charts for monitoring therapeutic processes has become popular lately. As the application of traditional control charts in the therapeutic processes may be misleading due to the inherent differences between patients, a multifactor correlated risk measure is considered in monitoring of these processes. Therefore, using risk-adjusted control charts for monitoring the therapeutic processes is of interest to practitioners. Furthermore, in health care monitoring, statistical models should account for abnormal distributions and outlier data to minimize misinterpretations of monitoring schemes. This study proposes a risk-adjusted multivariate Tukey's cumulative sum (RA-MTCUSUM) control chart. The proposed method is a combination of the accelerated failure time (AFT) regression model, the Tukey's control chart (TCC) featuring robustness against abnormality, and the multivariate cumulative sum (MCUSUM) control chart for monitoring multivariable process. Simulation experiments are performed to evaluate the performance of the proposed control chart using the average run length (ARL) measure. Results show that the RA-MTCUSUM control chart has better performance in comparison with traditional ones for monitoring various distributions (normal and non-normal). Based on the simulation results, outlier data do not disturb the proposed control chart's performance. Moreover, applying the RA-MTCUSUM control chart to a real-world dataset related to sepsis patients of a hospital located in Tehran, Iran indicates that the control chart has more reasonable performance than the traditional control charts in the real applications due to its robustness.     

Determination of time-dependent protoporphyrin IX concentration for photodynamic therapy dosimetry in a mice colon tumor model using fluorescence spectroscopy

Photodynamic therapy (PDT) is an effective treatment method for various types of invasive tumors. The efficiency of PDT treatment depends, to a great extent, on optimal dosimetry of light, the photosensitizer used, and on tissue oxygenation. Fluorescence spectroscopy can be employed for measurement of drug concentration in target tissue and can provide a basis for in vivo evaluation of treatment efficiency. We have developed an integrated system that can be used to determine photosensitizer concentration in vivo based on fluorescence measurements. In our study, we performed fluorescence measurements on colon tumors of Balb/c mice in which CT26 cells were injected subcutaneously in the right flank. 5-Aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) was used as the photosensitizer. ALA was administered intraperitoneally at a dose of 200 mg/kg and PpIX fluorescence profiles were followed up to 34 h after ALA administration. Maximum fluorescence intensity was found 8 h after ALA administration. Also, we determined the relationship between PpIX concentration in colon tumor tissue of Balb/c mice and its fluorescence intensity at the peak of the spectrum (635 nm). This was used to determine the PpIX content in the target tissue as a function of time after ALA administration.