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The purpose of this paper is to optimize the performance of direct methanol fuel cells for portable applications by combining a non‐linear, fully coupled circuit model and a stochastic optimization procedure.

A novel non‐linear equivalent circuit that accounts for electrochemical reactions and charge generation inside catalyst layers, electronic and protonic conduction, methanol crossover through the membrane, mass transport of reactants inside diffusion layers is presented. The discharge dynamic of the fuel cell, depending on the initial methanol concentration and on the load profile, is modelled by using the mass conservation equation. The equivalent circuit is interfaced to a stochastic optimization procedure in order to maximize the battery duration while minimizing fuel crossover.

In the proposed circuit scheme, unlike semi‐empirical models, lumped circuit parameters are derived directly from mass transport and electric equations in order to fully describe the dynamic performance of the fuel cell. Physical and geometrical parameters are optimized in order to improve the system runtime. It is shown that a combined use of fuel cells and lithium batteries can improve the runtime of portable electronic devices compared to traditional supply systems based on lithium batteries only.

The one‐dimensional model of the micro fuel cell does not take into account possible transverse mass and electric charge flows in the fuel cell layers; most of the geometric and physics model parameters cannot be estimated from direct in situ or ex situ measurements.

Direct methanol fuel cells are nowadays a promising technology for replacing or complementing lithium batteries due to their high energy density. Most limiting features of direct methanol fuel cells are the fuel crossover and its slow oxidation kinetics. By using the proposed approach, fuel cell parameters can be optimized in order to enhance the discharge runtime and to reduce the methanol crossover.

The equivalent circuit model with optimized lumped non‐linear parameters can be used when designing power management units for portable electronic devices.

The purpose of this study was to examined the health effects of raw and cooked aqueous and methanol extracts of Vigna unguiculata on kidney function in Wistar rats.

Thirty-six Wistar rats (weighing 160 ± 10 g) were randomly assigned into nine (9) groups (n = 4). Group I (control): no extract. Groups II and III (aqueous extract of the cooked 350 mg/kg and 550 mg/kg). Groups IV and V (methanol extracts of cooked 350 mg/kg and 550 mg/kg). Groups VI and VII (methanol extracts of raw 350 mg/kg and 550 mg/kg). Groups VIII and IX (aqueous extract of raw 350 mg/kg and 550 mg/kg). After the seventh day of the trial, the rats were euthanized with chloroform, and blood samples were collected for biochemical analysis.

Results showed that the doses applied for cooked and raw V. unguiculata significantly (p < 0.05) enhanced kidney functions by increasing the body weight, glucose level, concentration of serum urea, creatinine, total protein, potassium and chloride in test groups compared with control. The packed cell volume and haemoglobin concentrations of raw aqueous extract at 550 mg/kg (36.5 ± 5.1; 12.3 ± 2.8) were significantly (p = 0.001) higher (29.8 ± 11.8; 10.3 ± 3.9) than the 350 mg/kg dose of the same extract, and cooked aqueous extract at 350 mg/kg dose was significantly (p = 0.001) higher (28.0 ± 10.1; 9.3 ± 3.4) than that of 550 mg/kg (25.8 ± 4.9; 8.8 ± 3.9) dose of the extracts.

The nutritional content of V. unguiculata potentially can augment the nutritional content of a diet and to a large extent, the regular consumers’ health. Essentially, V. unguiculata is composed of both macro and micronutrients capable of promoting normal kidney function.

This paper aims to evaluate the antimicrobial and antioxidant activity of ethanol, methanol and aqueous extracts of the jujube fruit.

The fruit samples were harvested from Ziziphus lotus L. in three regions of Morocco: Aïn Chifae (Immouzer), Saiss (Fez) and Guercif. The fruit extracts were obtained by Soxhlet method using ethanol, methanol and water, and then a phytochemical screening was done for each extract. Total phenolic and total flavonoids contents were also determined. Afterward, the antimicrobial activity of the studied extracts was evaluated using the broth microdilution method. To estimate the total antioxidant effect of these extracts, the DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging and phosphomolybdate tests were performed.

Results showed that the highest content of polyphenols and flavonoids was found for ethanol and methanol extracts, while the lowest content was found in the aqueous extracts for all populations studied. Thus, results showed that the highest content of phenolic compounds was recorded in the population of Fez. Methanol extract of this population was the richest in polyphenols (30.36 mg/g) and in flavonoids (13.03 mg/g). The antimicrobial tests showed that Enterococcus faecalis and Pseudomonas aeruginosa were the most sensitive (6.25 mg/ml), compared to the other tested strains. Based on the minimal bactericidal concentrations/minimal fungicidal concentration or MFC/MIC ratio, it seems that ethanol extracts showed a bactericidal effect against Escherichia coli, Staphylococcus aureus and Bacillus subtillis, and a bacteriostatic effect against Enterococcus faecalis. On the other hand, the methanol extract showed bacteriostatic effect against Enterococcus faecalis and Pseudomonas aeruginosa. In addition, methanol extracts of Ziziphus lotus have significant antioxidant potent.

Methanol and ethanol extracts of Ziziphus lotus fruit have demonstrated strong antimicrobial effect. Moreover, the authors were able to show that the extract of Ziziphus lotus fruit has a very important antioxidant power.

The purpose of this paper is to investigate the performance of Passive Direct Methanol Fuel Cell (PDMFC) experimentally using various Membrane Electrode Assembly (MEA) shapes such as square, rectangle, rhombus, and circle with equal areas and equal perimeters. The variation in MEA shape/size is achieved by altering gasket openings in the dynamic regions.

In the equal areas of MEA shapes, gasket opening areas of 1963.5 (+/−0.2) mm2 are used. Whereas in the equal perimeters of shapes, gasket opening perimeters of 157.1 (+/−0.2) mm are used. In this experimentation, Nickel-201 current collectors with 45.3% of circular openings are used on both the anode and cathode sides. The experiment is carried out at a 5 molar methanol concentration to find out the highest power density of the cell.

In the equal areas, among the shapes that are chosen for investigation, the square shape opening consisting of a perimeter of 177.2 mm has developed a maximum power density of 6.344 mWcm⁻² and a maximum current density of 65.2 mAcm⁻². Similarly, in equal perimeters, the rhombus shape opening with an area of 1400 mm2 has developed a maximum power density of 7.714 mWcm⁻² and a maximum current density of 85.3 mAcm⁻².

The novelty of this research work is instead of fabricating various shapes and sizes of highly expensive MEAs, the desired shapes and sizes of the MEA are achieved by altering gasket openings over dynamic regions to find out the highest power density of the cell.

The purpose of this study was to evaluate the extract of Moringa stenopetala seed oil, by organic solvents (methanol and hexane), for its efficacy against microbial activity on cotton fabrics. The selected microbes for the study were two types of bacteria which are Gram-positive (S. aureus) and Gram-negative (E. coli).

Two types of bacteria, Gram-positive (S. aureus) and Gram-negative (E. coli) were used. The extract was applied on fabrics at a concentration of 5, 10 and 15 g/L using the pad-dry-cure method and antibacterial activities verified by the bacterial-growth reduction method. The treated fabrics were evaluated for antimicrobial activity against the bacteria before and after 15 washing cycles. The extract was examined for molecular structural change using fourier transform infrared spectroscopy (FTIR) and physical properties of the fabric; tensile strength, elongation, air permeability, stiffness and wettability were evaluated.

Results showed treated fabrics reduces the growth of Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria from 77.6%–100% before wash and 45.8%–85.2% after wash for both extract concentrations. Comparing extracts, hexane extract reduces all bacteria growth than methanol extract for both extract concentrations while S. aureus was more susceptible to antimicrobial agents than E. coli at a lower concentration. As result, the tensile strength and air permeability were relatively lower than untreated ones without affecting the comfort properties of the fabric.

This study indicates that the Moringa stenopetala seed oil extract has a strong antimicrobial activity.

7075-T6 is the most widespread structural aluminium alloy due to its high mechanical strength. However, use of this alloy in critical aeronautic, maritime, and automotive sectors is limited by the susceptibility of T6 treatment to cracking and pitting corrosion. To improve fatigue behaviour in aggressive environments, several authors have proposed the use of different coatings to protect the substrate. Studies have investigated the application of thin hard coatings on light alloys by physical vapour deposition (PVD). Different contributions of residual stresses, thermal modification of the substrate, and mechanical interaction between the coating and aluminium substrate were investigated. The purpose of this paper is to investigate the rotating bending fatigue behaviour (R=−1) of 7075-T6 PVD diamond-like carbon (DLC)-coated specimens in air and in a corrosive environment. Tests were conducted at different applied stresses. Scanning electron micrographs of the fracture surface are provided to investigate the influences of mechanical and environmental driving forces on the failure mechanism.

The paper conducted an experimental study of the fatigue resistance of DLC coatings on a 7075-T6 substrate for corrosion protection at long and short fatigue lives, which includes rotating bending fatigue tests, step-loading fatigue test procedure, tests in aggressive environment (methanol), tests at high and low fatigue lives, analysis of the fracture surface, and analysis of the driving forces.

Tests performed in air showed that the coating anticipates crack nucleation for high applied loads, whereas for lower loads, the difference among fatigue curves decreases. This result is very interesting from an industrial standpoint because the obtained material shows improved corrosion and wear resistance, without the fatigue resistance loss generally associated with hard coatings. The methanol environment accelerates crack nucleation and propagation, resulting in a sensible deterioration of the fatigue behaviour. A minimum soaking time seems to be necessary before the damaging effect of the environment begins. The coating has a certain protective effect against the environment, but this protection is insufficient for the specimen to achieve fatigue limits beyond those of the uncoated specimens. This deficiency can be related to small pores or defects in the coating, which allow contact between the substrate and the environment. Further tests are necessary to verify whether there exists a load under which the fatigue behaviour of the coated specimens is better than that of the uncoated specimens. Crack nucleation due to fatigue occurs close to the outer surface for all observed samples. For coated samples tested at the lowest stress level, crack nucleation seems to be located below the surface. This observation means that premature coating cracking, which characterises the nucleation mechanism at higher loads, did not occur at lower stress levels. The fracture surface of uncoated samples was clearly damaged by the aggressive solution, justifying the poor fatigue resistance.

The obtained data do not represent actual S-N curves, which would necessitate a larger number of tests with proper statistics. Nevertheless, some indications of the DLC effects on 7075-T6 specimens in air and methanol environments can be deduced. The step-loading technique seems to be critical for tests in corrosive environments, probably because the total soaking time in the corrosive environment is generally higher than it is for the single-run test.

The originality of the paper lies in the application of the step-loading test procedure to quickly detect the mechanical and chemical driving forces that control the damage and structural integrity of light alloys components in very aggressive environments.

Salak (Salacca zalacca) is an underutilised fruit. The bioactivities of this fruit have rarely been studied scientifically. Thus, the present study aimed to determine the antioxidant activity of extracts derived from the peel, fruit and kernel of the Salak fruit, as well as the hypoglycemic and anti-hypertensive properties of Salak peel extracts.

The peel, fruit and kernel of the Salak were extracted using distilled water, methanol and ethanol. Antioxidant activities, angiotensin-converting enzyme (ACE) and alpha-amylase inhibition properties of the extracts were estimated via in vitro standard methods. Besides, the total phenolic content (TPC) and total flavonoid content (TFC) of the extracts were also determined in the present study. The antioxidant activities of different parts of Salak extracts were determined by ferric-reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC) methods. Percent of radical scavenging properties were calculated via DPPH assay. The hypoglycemic and anti-hypertensive properties of Salak peel were evaluated using alpha-amylase inhibition and ACE assays, respectively.

Fruit extracts of Salak in methanol were found to exhibit the highest TPC (10.27 ± 0.12 mg GAE/g), TFC (11.04 ± 0.89 mg CE/g) and antioxidant properties amongst all samples whereby the TPC and TFC were strongly correlated with antioxidant activities. On the other hand, distilled water extracted Salak kernel showed to have the lowest TPC (0.53 ± 0.05 mg GAE/g), TFC (0.37 ± 0.01 mg CE/g) and antioxidant properties amongst all the Salak extracts. Peel extracts exhibit comparable antioxidant activities with fruit extracts in the current findings. In addition, peel extracts indicated some extend of ACE and alpha-amylase inhibition activities regardless of the solvents used. Methanol and ethanol peel extracts indicated no significant difference (p < 0.05) ACE (98%) and alpha-amylase (90%) inhibition activities. However, distilled water extracted Salak peel showed significantly lower ACE and alpha-amylase inhibition in comparison to methanol and ethanol peel extracts.

The present findings suggested that the fruit of Salak exhibits the highest antioxidant properties, followed by the peel and lastly, the kernel, which shows the lowest antioxidant properties amongst all the samples. The results also indicated that the peel extracts have ACE and alpha-amylase inhibition activities.

Introduction Corrosion and the electrochemical behaviour of metals in non‐aqueous solvents are of current interest. The knowledge of the influence of a certain solvent on the dissolution processes is valuable from a practical point of view. A thorough survey of the literature reveals that little attention has been focused on aluminium in organic solvents. Due to its wide use in industry, this investigation shows the behaviour of aluminium in mixed solvents composed of methanol, ethanol or acetonitrile with water in acidic 1M HCl solutions. The corrosion of aluminium was studied by using the accelerated weight loss method.

The Materials and Processes Research Laboratory of the Electronics Manufacturing Productivity Facility (EMPF) is undertaking a research project to examine the use of solvents in a vapour decreasing process. Fourteen solvents are included in this project. During the research, it was found that the concentration of the denaturant Methanol (MEOH) in the trichlorotrifluoroethane/ethanol (TCF/ethanol) mixture in the vapour degreaser boil sump was being depleted. The fresh material had a concentration of 0 · 35 percent MEOH by volume but the test data showed that this concentration dropped to levels between 0·19 and 0·11 percent MEOH. MEOH depletion in trichlorotrifluoroethane/methanol (TCE/methanol) azeotrope was also detected. The alcohol depletion that was discovered is a concern because when one component of an azeotrope breaks down, the entire azeotrope is affected and the constant boiling feature is no longer present. MEOH separation may also be a flammability hazard and may decrease the Threshold Limit Value (TLV) of the solvent because of MEOH toxicity. It was determined that the MEOH depletion was caused by the molecular sieve or desiccant adsorbing the alcohol. Recommendations are offered to minimise the flammability hazard associated with a MEOH‐adsorbing molecular sieve.

The purpose of this paper is to simulate micro direct methanol fuel cells (DMFCs) for portable electronic devices by means of a non‐linear equivalent circuit based on a fully coupled, dynamic, electrochemical model.

The equivalent circuit accounts for electrochemical reactions and electric current generation inside the catalyst layers, electronic and protonic conduction, fuel crossover across the membrane, mass transport of reactants inside the diffusion layers. The V‐I characteristic of the device is obtained by combining mass transport and electric equations. The transient dynamics is accounted for by an equivalent capacitance, while the slow dynamics by the mass conservation equation. The equivalent circuit is embedded in the Matlab/Simulink^® dynamic model of a hybrid system, consisting of a micro fuel cell and a Li‐ion rechargeable battery.

An original equivalent circuit of a passive DMFC suitable for static and dynamic simulations under variable loading conditions is proposed and validated.

The one‐dimensional model of the micro cell does not take into account transverse mass transfer and current density variations in the cell layers, which can be due to non‐homogeneous materials or to the complex dynamics of the convective mass flow in the reservoir and in the room air.

The equivalent circuit can be used for simulating the dynamic performance in realistic operating conditions when the fuel cell is used to supply the electronic equipment through a power management unit.

The DMFC is described from an electrical point of view as a controlled non‐linear generator; such equivalent representation is particularly suited for designing power management units for electronic portable devices.