The hematological effects of methyl parathion in rats

The effects of methyl parathion (MP) at sublethal concentration on hematological constituent [red blood corpuscles (RBC), white blood corpuscles (WBC), mean cell volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), platelet (PLT) counts, hemoglobin (Hb) and hematocrite (HCT) levels] and serum damage marker enzymes [aspartate aminotransferase (AST), alanin aminotransferase (ALT), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH)] of rats were investigated under laboratory conditions. 5 and 10 ppm dosages of MP were administered orally to six female rats ad libitum during the tests for 4 weeks consecutively. MP treatments caused different effects on the hematological constituents and the serum marker enzymes of the treatment groups as compared to the controls. According to the results, MP treatments increased significantly the levels of serum marker enzyme activities except for ALT with both dosages and LDH with 5 ppm dosage. Also, the hematological constituents were affected by MP. For example, WBC significantly increased in rats treated with both dosages of MP whereas the other hematologic constituents did not change at 5 and 10 ppm of MP treatments. The observations presented led us to conclude that the administration of subacute MP elevates tissue damage serum marker enzymes, and increases the number of WBC in rats. These data, along with the determined changes suggest that MP produce substantial systemic organ toxicity in rats during the period of a 28-day subacute exposure.     

RESIDUAL STRESS FIELDS DURING FATIGUE CRACK GROWTH

This study outlines the distinction between (1) residual stresses at an ideal crack tip, undergoing reversed deformation in the absence of crack closure, and (2) additional residual stresses generated due to plasticity induced closure upon fatigue crack growth. Residual stresses resulting from reversed deformation in plane strain were higher compared to the plane stress case, while residual stresses generated behind the crack tip were more significant in plane stress compared to plane strain. The origin of these residual stresses was studied for two specimen geometries over a wide range of loading conditions. We define a new crack tip parameter, S_tt as the applied stress level that corresponds to the development of tensile stresses immediately ahead of crack tips. The S_tt levels were significantly higher for a fatigue crack than for an ideal crack. We attribute the difference in S_tt levels between these two cases to plasticity induced closure. The results demonstrate the importance of the S_tt parameter, since the stresses ahead of crack tips could remain compressive even when the crack surfaces are open. Moreover, the study emphasizes the need, when describing fatigue crack growth, to incorporate both the closure concept and residual stress field ahead of a crack tip.     

Dry Sliding Wear Behavior of (MWCNT + GNPs) Reinforced AZ91 Magnesium Matrix Hybrid Composites

Metals and Materials International - This study aims to improve tribological performance of magnesium alloy with the addition of carbonaceous (C-based) reinforcements. Synergetic effects of MWCNT...     

Exergetic modeling and performance evaluation of solar water heating systems for building applications

Solar water heating (SWH) is a well-proven renewable energy technology and has been used in many countries of the world. The basic technology is straightforward, although there are a variety of various types of SWH systems. In the performance assessment of SWH systems, energy analysis (first law) method has been widely used, while the number of the studies on exergetic assessment is relatively low. The SWH system investigated consists of mainly three parts, namely a flat plate solar collector, a heat exchanger (storage tank) and a circulating pump. The main objectives of the present study are as follows, differing from the previously conducted ones: (i) to model and assess SWH systems using exergy analysis (second law) method as a whole, (ii) to investigate the effect of varying water inlet temperature to the collector on the exergy efficiencies of the SWH system components, (iii) to study some thermodynamic parameters (fuel depletion ratio, relative irreversibility, productivity lack and exergetic factor) and exergetic improvement potential, and (iv) to propose and present an exergy efficiency curve similar to the thermal efficiency curve for solar collectors. The system performance is evaluated based on the experimental data of the Izmir province, Turkey, which is given as an illustrative example. Exergy destructions (or irreversibilities) as well as exergy efficiency relations are determined for each of the SWH system components and the whole system. Exergy efficiency values on a product/fuel basis are found to range between from 2.02 to 3.37%, and 3.27 to 4.39% at a dead (reference) state temperature of 32.77 °C, which is an average of ambient temperatures at eight test runs from 1.10 to 3.35 p.m., for the solar collector and entire SWH system, respectively. An exergy efficiency correlation for the solar collector studied was also presented to determine its exergetic performance. It is expected that the model presented here would be beneficial to the researchers, government administration, and engineers working in the area of SWH systems for residential applications.     

Nano‐RuO2‐Decorated Holey Graphene Composite Fibers for Micro‐Supercapacitors with Ultrahigh Energy Density

Compactness and versatility of fiber‐based micro‐supercapacitors (FMSCs) make them promising for emerging wearable electronic devices as energy storage solutions. But, increasing the energy storage capacity of microscale fiber electrodes, while retaining their high power density, remains a significant challenge. Here, this issue is addressed by incorporating ultrahigh mass loading of ruthenium oxide (RuO₂) nanoparticles (up to 42.5 wt%) uniformly on nanocarbon‐based microfibers composed largely of holey reduced graphene oxide (HrGO) with a lower amount of single‐walled carbon nanotubes as nanospacers. This facile approach involes (1) space‐confined hydrothermal assembly of highly porous but 3D interconnected carbon structure, (2) impregnating wet carbon structures with aqueous Ru³⁺ ions, and (3) anchoring RuO₂ nanoparticles on HrGO surfaces. Solid‐state FMSCs assembled using those fibers demonstrate a specific volumetric capacitance of 199 F cm^?3 at 2 mV s^?1. Fabricated FMSCs also deliver an ultrahigh energy density of 27.3 mWh cm^?3, the highest among those reported for FMSCs to date. Furthermore, integrating 20 pieces of FMSCs with two commercial flexible solar cells as a self‐powering energy system, a light‐emitting diode panel can be lit up stably. The current work highlights the excellent potential of nano‐RuO₂‐decorated HrGO composite fibers for constructing micro‐supercapacitors with high energy density for wearable electronic devices.     

Bioattenuation of Detergent Plant Effluents Enhanced via Single Microbial Augmentations

Due to natural attenuation, anionic detergents in surface waters are not inferred as big environmental issues. However, the effluents from large industrial areas with high detergent concentrations can have significant local impacts. These circumstances can be diminished by using efficient detergent‐degrading bacterial isolates through bioaugmentation. In this study, detergent plant effluents were analysed by using a methylene blue active substance assay to determine detergent content during natural attenuation processes, and after single augmentations of 12 anionic detergent‐degrading bacterial isolates with high detergent tolerating abilities in batch microcosms. Maximum bioattenuation of detergents was determined as 56 % after 66 h incubation under the conditions that mimicked the natural environment. Bioattenuation was enhanced as much as 83 and 91 % in 78 h incubation time through single microbial augmentations of filter‐sterilized and non‐sterilized effluents, respectively. Eight Pseudomonas and one Aeromonas species were found to be highly competitive by showing high biodegradation abilities in pure culture experiments as well as enhancing degradation of detergents in both filter‐sterilized and non‐sterilized effluents through their single augmentations. Although remaining three isolates, namely Pseudomonas fluorescens SDS6, P. resinovorans SDS10‐2, and P. corrugata SDS10‐3 displayed lower degrading abilities in pure culture experiments than the natural attenuation, they later turned out to be actively enhancing the degradation of detergents during their single augmentations.     

Mechanical and electromechanical properties of piezoelectric ceramic fibers drawn by the alginate gelation method

Piezoelectric ceramic fibers are widely used in piezocomposite devices. The various methods that are used to draw ceramic fibers differ in the way the fiber form is obtained, which in return closely affects the density, uniformity and the properties of the fibers that are obtained at the end. In this study, the processing-property relationship in the piezoceramic fibers drawn using the alginate gelation method is investigated, with a focus on the mechanical and electrical properties of individual fibers. Fibers with a Weibull strength of 65.3 MPa, remanent polarization of 22 μC/cm² and a total bipolar field induced strain of 0.25% under an electric field of 2.5 kV/mm, piezoelectric coefficient of 300 pm/V and dielectric constant of 3323 were produced. 1-3 piezocomposite devices prepared from these fibers had a 6 dB higher free-field voltage sensitivity and a 50% wider bandwidth compared to a solid disk transducer of the same dimensions.     

Electrospun nanofiber polyacrylonitrile coated separators to suppress the shuttle effect for long-life lithium–sulfur battery

Polymeric coating on the separator with effective polysulfides diffusion inhibition can provide intimate contact between intermediate polysulfides and conductive layer of separator for high-energy lithium–sulfur (Li–S) batteries. Herein, polyacrylonitrile–poly(1,5-diaminoanthraquinone) (PAN/PDAAQ) and PAN-potassium functionalized graphene (PAN/K-FGF) nanofibers are synthesized via electrospinning method and act as effective separators for Li–S batteries to minimize polysulfides diffusion toward the anode. PAN/K-FGF coated separator shows capacity retention of 768 mAh g⁻¹ after 100 cycles at 1C. The capacity maintains at 419 mAh g⁻¹ after 500 cycles. PAN/PDAAQ nanofibers are coated on glass fiber separator functions as physical and chemical barrier for polysulfides diffusion. Therefore, the cell with PAN/PDAAQ coating on the separator demonstrates capacity retention of 881 mAh g⁻¹ after 100 cycles at 1C and small capacity decay rate of 0.11% per cycle resulted in 800 cycles at 1C. PAN/PDAAQ could define as an ideal separator material for Li–S batteries. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48606.