Marine pollution effects on the reproduction process of Perinereis cultrifera (Annelida, Polychaeta) in Algeria

The Mediterranean Sea is one of the busiest areas worldwide in terms of maritime activity and faces considerable anthropogenic disturbances, such as pollution by hydrocarbons and heavy metals. This study evaluated the environmental status of three sites on the Algerian coast using the annelid polychaete Perinereis cultrifera as a biomonitoring sentinel species. It included different reproductive parameters such as oocyte diameter, frequency distributions, sexual maturity index, biochemical quantitative parameters represented by the vitellogenins and vitellins, and a histological study of the coelome during the reproductive period. The results showed that the females collected from El-Kala (healthy site) have the highest diameter 304.1 ± 24.3 μm during April but the values were increased in Annaba 290.0 ± 21.0 μm and Skikda 245.3 ± 26.7 μm. Significant differences were observed between worms from the three study sites during the three months of the study. Moreover, the size-frequency indicated that a relatively high proportion of females containing mature oocytes was found in April in females collected at El-Kala 52.4%, 46.4% in females collected at Annaba and 36.7% in females collected at Skikda. In addition, regarding the sexual maturity index, the highest values were recorded in April (3.8, 2.9, and 1.9) at the El-Kala, Annaba, and Skikda study sites. However, the biochemical analysis demontrated that the highest mean concentration of vitellogenin was in females of El-Kala (5.3 ± 0.3 µg/mg of coelomic fluid) in April, and the lowest mean concentration was measured in females of Skikda (1.5 ± 0.2 µg/mg of coelomic fluid). Therefore, the highest mean concentration of vitellin was measured in females of El-Kala (4.4 ± 0.2 µg/mg of oocytes) in April, while the lowest mean concentration of vitellin was measured in females of Skikda (1.02 ± 0.2 µg/mg of oocytes) in May. Significant differences were observed between worms from the three sites during the three months of the study. Furthermore, histological observations revealed that oogenesis was asynchronous, with oocytes at different stages of vitellogenesis simultaneously present. The structure of the oocytes of females collected at El-Kala showed intense vitellogenic activity due to the presence of very dense yolk cells. In contrast, the oocytes of the females collected from the two polluted sites (Annaba and Skikda) were small, vitellogenesis presented low intensity, and yolk cells were less frequent at the periphery and less uniform at the cytoplasmic mass; the nucleus was smaller, indicating a slower vitellogenic activity. These observations confirm the previously obtained results

Systems responses to progressive water stress in durum wheat

Durum wheat is susceptible to terminal drought which can greatly decrease grain yield. Breeding to improve crop yield is hampered by inadequate knowledge of how the physiological and metabolic changes caused by drought are related to gene expression. To gain better insight into mechanisms defining resistance to water stress we studied the physiological and transcriptome responses of three durum breeding lines varying for yield stability under drought. Parents of a mapping population (Lahn x Cham1) and a recombinant inbred line (RIL2219) showed lowered flag leaf relative water content, water potential and photosynthesis when subjected to controlled water stress time transient experiments over a six-day period. RIL2219 lost less water and showed constitutively higher stomatal conductance, photosynthesis, transpiration, abscisic acid content and enhanced osmotic adjustment at equivalent leaf water compared to parents, thus defining a physiological strategy for high yield stability under water stress. Parallel analysis of the flag leaf transcriptome under stress uncovered global trends of early changes in regulatory pathways, reconfiguration of primary and secondary metabolism and lowered expression of transcripts in photosynthesis in all three lines. Differences in the number of genes, magnitude and profile of their expression response were also established amongst the lines with a high number belonging to regulatory pathways. In addition, we documented a large number of genes showing constitutive differences in leaf transcript expression between the genotypes at control non-stress conditions. Principal Coordinates Analysis uncovered a high level of structure in the transcriptome response to water stress in each wheat line suggesting genome-wide co-ordination of transcription. Utilising a systems-based approach of analysing the integrated wheat's response to water stress, in terms of biological robustness theory, the findings suggest that each durum line transcriptome responded to water stress in a genome-specific manner which contributes to an overall different strategy of resistance to water stress

Corrosion inhibition of stainless steel N304 by dihydroxy benzyl phosphonic acid in 0.5 M H2SO4: Experimental and theoretical studies

69-75Dihydroxy benzyl phosphonic acid (DPA) has been studied as inhibitor against stainless steel N304 in 0.5 M sulfuric acid solution using the potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The inhibition efficiency was found to vary with the concentration of the inhibitor and elongating the immersion time. Electrochemical impedance spectroscopy (EIS) measurements confirmed the polarization data. The adsorption of (DPA) on the stainless steel N304 surface follow Langmuir adsorption isotherm. The results of quantum chemical calculations and experimental efficiencies of inhibitor were subjected to correlation analysis

Experimental and detailed DFT/MD simulation of α-aminophosphonates as promising corrosion inhibitor for XC48 carbon steel in HCl environment

Background: Corrosion is a pervasive issue in several industries, causing safety hazards and substantial economic losses. α-aminophosphonate substances have recently garnered attention for their ability to inhibit corrosion. In this study, two specific α-aminophosphonate molecules, namely diethyl(furan-2-yl(phenylamino)methyl) phosphonate (AMP1) and diethyl((2methoxyphenyl) amino) (thiophene-2-methyl) phosphonate (AMP2) were evaluated for their potential as anticorrosion agents for XC48 carbon steel under acidic conditions. Methods: Their corrosion inhibition was examined towards XC48 carbon steel under 1.0 M HCl solution utilizing the electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), atomic force microscope (AFM), scanning electron microscope (SEM), contact angle, Density functional theory (DFT), molecular dynamics (MD), and atoms in molecule (AIM). Significant findings: Results showed that AMP1 and AMP2 had inhibition efficiencies of 83.34% and 63.82% for EIS and 82.70% and 74.57% for PDP, respectively. The inhibition mechanism involved adsorption of the additives onto the metal surface via Langmuir isotherm. The study also demonstrated the influence of temperature on inhibition efficiency, with nearly 70% inhibition observed at 298 to 323 K. AFM and SEM analyses revealed chemisorption coating formation inhibiting acid attack, and contact angle analyses showed the surface to be hydrophobic. Theoretical analyses using DFT, MD, and AIM were used to clarify the inhibitors' adsorption effect on XC48 steel, showing a high agreement with experimental findings

Effect of Titanium on the Mechanical Properties and Microstructure of Gray Cast Iron for Automotive Applications

Lamellar gray cast iron, with a mainly pearlitic microstructure, is widely used in the automotive industry, mostly in the manufacturing of brake disks. This work analyzes in depth the effects of small variations of titanium content on the microstructure and mechanical properties of cast iron brake disks. For this purpose, eight different heats of EN-GJL-250 cast iron were selected, with a similar chemical composition but with different titanium contents, varying from 0.013 to 0.031%. The drops in mechanical strength and hardness values measured on the high-Ti samples were correlated to microstructural variations quantitatively observed by means of optical and scanning electron microscope. It was found that titanium combines to form titanium nitrides, suppressing the beneficial microstructural effects of nitrogen at solidification. Residual nitrogen, if present in sufficient quantity, promotes the nucleation of primary austenite from the liquid and the formation of a fine microstructure, with small eutectic cells and lower graphite content. Such a microstructure provides brake disks with better mechanical properties. The interpretation of results was further supported by thermal analysis and thermodynamic calculations