NaCl Medium Research Articles

Chemical synthesis and characterization of a soluble copolymer poly (methoxyaniline-co-orthotoluidine), application as corrosion inhibitor of carbon steel in 3% NaCl medium

A copolymer and polymers were synthesized by chemical oxidative polymerization using ammonium persulfate as an oxidant in hydrochloride aqueous medium. The resultant copolymer and polymers were characterized by Fourier transform infrared (FTIR), UV–vis spectroscopy, XRD and TGA analysis, which reveals a significant improvement in the thermal stability of the copolymer. The copolymer is soluble in various organic solvents such as DMF, DMSO, THF and acetonitrile. The performance of this copolymer as corrosion inhibitor for carbon steel corrosion in 3% NaCl solution was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The copolymer acts as an effective corrosion inhibitor for carbon steel. The inhibition process is attributed to the formation of an adsorbed film of copolymer on the metal surface which protects the metal against corrosion. The experimental results indicate that copolymer has good corrosion inhibition performance and the protection efficiency increased with increase in inhibitor concentration. The molecular structure effect on the corrosion inhibition efficiency was investigated using DFT calculations. The parameters for the structural and electronic systems were calculated and discussed. The obtained results show that the experimental studies agree well and confirm that the copolymer is the good inhibitor.

Effects of Minor Gadolinium Addition and T4 Heat Treatment on Microstructure and Properties of Magnesium

Mg–Gd alloys are candidates for degradable implants combining favorable mechanical and corrosion properties. Gd has a high solid solubility in Mg and an acceptable biocompatibility. The influences of different amount of Gd additions and solid solution (T4) treatment on mechanical properties and corrosion in 0.9 wt% NaCl and cell culture medium (CCM) of magnesium are systematically investigated. The effects of Gd are clarified by microstructural characterizations as well as stress and degradation analysis. It is shown that minor Gd additions to pure Mg lead to Gd solid solution in Mg (α) and the formation of Mg5Gd intermetallic particles (IMPs), which increase the hardness, tensile, and compressive strength. The GdH2 phase is found in low‐alloyed Mg–Gd alloys. The corrosion rate (CR) is increased by the addition of more Gd due to the increased kinetics of the cathodic reaction. However, the resistance to degradation is effectively improved by T4 heat treatment due to the dissolution of IMPs. The reduced susceptibility to pitting can be achieved by a minor Gd addition and T4 heat treatment. The Mg–2Gd alloy is a potential candidate for implants due to its good combination of tailorable mechanical properties and low homogeneous in vitro degradation rate (DR).

Effect of carbon content on the structural, mechanical and corrosion properties of TiC films deposited using a HiPIMS discharge

TiCx thin films have been deposited on steel substrates using High Power Impulse Magnetron Sputtering (HiPIMS) under Ar-C2H2 atmosphere. The effect of varying the acetylene content on the deposition process, and on the structural, mechanical and corrosion resistance properties was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), nanoindentation, scratch testing, potentiodynamic polarization, electrochemical impedance measurements (EIS), and salt spray. This study showed that an increase of the carbon ratio affected the deposited TiC coatings morphology and mechanical properties, with hardness values reaching up to 25 GPa. The near-stoichiometric coating exhibited the highest hardness while maintaining improved toughness, resistance to plastic deformation and resistance against crack propagation thanks to their nanocomposite structure. In contrast, corrosion tests showed that the understoichiometric coatings exhibited the best corrosion resistance in a 3.5 % wt NaCl medium. The drop of the corrosion performances of TiCx coatings deposited at higher acetylene flow rate was linked to a growth-related defects extending throughout the coating thickness, formed due to micro-droplet ejection from the target as evidenced by SEM analysis.

Synthesis and characterization of phenolphthalein derivatives, detailed theoretical DFT computation/molecular simulation, and prevention of AA2024-T3 corrosion in medium 3.5% NaCl

BackgroundAluminum alloy corrosion prevention is a significant problem in the industry. The development of an effective protection strategy is a popular research area. In this work, two organic inhibitors phenolphthalein (P1) and (3-oxo-1, 3-dihydroisobenzofuran-1,1-diyl)bis(4,1-phenylene) bis(4-methyl benzenesulfonate) (P2) were used in 3.5% NaCl medium for alloy AA2024-T3 corrosion mitigation. Corrosion inhibition behavior was investigated by a combination of experimental and theoretical studies. MethodsThe surface morphology of AA2024 -T3 has been identified by scanning electron microscopy coupled with Energy Dispersive X-Ray Spectroscopy (SEM/EDS), and Infrared spectroscopy (FT-IR) confirms the adsorption of functional groups on the surface of the aluminum alloy. Furthermore, the adsorption energies of P1 and P2 on Aluminium (111) interfaces were computed by Molecular Dynamics (MD), and quantum chemical computations (density functional theory, DFT) were chosen for obtaining basic electronic/atomic-scale details about the compound adsorption on target alloy aluminum and their active sites. Significant findingsThe effect of two organic inhibitors phenolphthalein (P1) and (3-oxo-1, 3-dihydroisobenzofuran-1,1-diyl)bis(4,1-phenylene) bis(4-methyl benzenesulfonate) (P2) on the corrosion protection of Aluminium alloy in 3.5% NaCl solution was examined using electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PPD) methods. The Total polarization resistance (RTot) increased, and the corrosion current density declined with the increasing inhibitor concentration. Inhibition efficiency revealed the maximum value of 85% for the P1 and 93% for P2 at 10−4 M, respectively. the two inhibitors were categorized as mixed-type inhibitors since they inhibited both cathodic and anodic corrosion.

Corn oil based cinnamate amide/Fe2O3 nanocomposite anticorrosive coating material

ObjectivesThe efforts are being focused to utilise sustainable resources such as vegetable oils, which are amenable to chemical transformations producing monomers and polymers yielding protective coatings. The present manuscript describes the preparation of nanocomposite coatings from corn oil (CO). MethodsCO was subjected to amidation followed by esterification by cinnamic acid producing CO cinnamate-amide (COCA). COCA was next enriched with Fe2O3 nanoparticles (COCA/ Fe2O3) and crosslinked with phenol formaldehyde to produce polymeric coatings on mild steel panels. ResultsCOCA obtained was rich in functional groups: benzene ring, conjugated with an acrylic group, ester and amide functional group with pendant alkyl chain, and terminal hydroxyl group. The multiple functional groups and nanoparticles offered good adhesion, scratch resistance and flexibility to the resulting nanocomposite coatings. COCA/Fe2O3 coatings showed good physico-mechanical properties and corrosion resistance performance in 3.5 wt% NaCl medium and can be safely used upto 225 °C.

Synthesis and Corrosion Inhibition Potential of Cerium/Tetraethylenepentamine Dithiocarbamate Complex on AA2024-T3 in 3.5% NaCl.

In this work, a cerium/tetraethylenepentamine dithiocarbamate complex was synthesized and evaluated for the corrosion inhibition capability on an AA2024-T3 Al alloy in a 3.5% NaCl medium. The synthesized compounds were characterized via spectroscopic techniques. The corrosion inhibition behaviour of the complex was elucidated by electrochemical measurements and surface analysis techniques. Based on electrochemical test results, the corrosion inhibition efficiency of the complex increases with the immersion time of aluminium alloy in the test solution. The corrosion inhibition reaches 96.80% when the aluminium is immersed in a 3.5% NaCl solution containing a corrosion inhibitor for 120 h. The potentiodynamic polarization test results show that the complex acts as a mixed-type corrosion inhibitor and the passive range is widened. The surface analysis methods reveal that the corrosion inhibition ability of the complex originated from the formation of a protective layer on the Al surface. This film is created from the physisorption and chemisorption of cerium ions and organic parts simultaneously released from the complex molecules.

Synergistic effect of Black cumin extract and zinc cations on the mild steel corrosion resistance improvement in NaCl solution; Surface and electrochemical explorations

Corrosion inhibitors are used to enhance the anti-corrosion properties of mild steel in corrosive environments. In this study, for the first time, a hybrid corrosion inhibitor based on Black cumin extract (BCE) and zinc cations was employed to mitigate the mild steel dissolution rate in NaCl media. The inhibitive film fabricated on the metal surface in the presence of BCE was characterized by scanning electron microscopy equipped with energy dispersive spectroscopy (SEM/EDS), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, Grazing Incidence X-ray Diffraction (GIXRD), and UV–vis tests. Also, the electrochemical impedance spectroscopy (EIS) and Potentiodynamic polarization tests were engaged in 3.5 wt%. NaCl solution to study the protection performance of the metal in the presence of inhibitors. Due to the fabrication of inhibitive film, the anti-corrosion properties of the mild steel are significantly enhanced in the presence of organic/inorganic corrosion inhibitors. The creation of the inhibitive film in the presence of hybrid corrosion inhibitors was proved through SEM analysis and electrochemical testing. Electrochemical tests proved a synergistic effect between the selected inhibitors. The inhibitor efficiency for hybrid corrosion inhibitor was calculated at about 95 %, and 90 % in EIS and polarization tests, respectively. FT-IR, Raman, and XRD tests' outcomes proved the complex inhibitors' film formation over the metal substrate.

Effect of the combination of organic acid solutions on tinplate corrosion

Tinplate corrosion as a result of canned food is typically tested in industry by tinplate in synthetic media based on single organic acids. However, the combination of organic acids, which is present in applied conditions, is not previously investigated in terms of its effect on tinplate corrosion mechanism. In this manuscript, we combine structural characterization of tinplate surfaces with electrochemical measurements, to investigate the corrosion mechanism of tinplate under acetic acid-NaCl, citric acid-NaCl, and a combined acetic acid, citric acid and NaCl media. The results show that the combined acid media causes does not result in a pronounced formation of a protective passivation layer, in contrast to the single acid based media. Our findings demonstrate the combined effects of the organic acids in corrosive media has to be taken into account for tinplate corrosion, as they can alter the corrosion mechanism. Furthermore, we show that combination of organic acids can accelerate tinplate corrosion testing in packaging industry. Thus, our findings can contribute to the design of new aging media for tinplate corrosion testing.

Critical insights from alloys and composites of Ni-based electrocatalysts for HER on NaCl electrolyte

It is critical to minimize the cost of materials and inputs used in hydrogen production and to create solutions for large-scale generation to reduce the cost of hydrogen produced. Seawater is a natural low-cost electrolyte with high Na + and Cl - concentrations, among other soluble salts. Chloride ions allow a highly corrosive media to the materials typically used as electrodes. In this work, we have prepared and tested different Ni-based catalysts for hydrogen evolution in NaCl-containing solutions. NiMo alloy, Ni(WO 3 ), and Ni(Nb 2 O 5 ) composites are compared and studied from a critical point of view to find a viable solution for catalysis in seawater electrolysis. The NiMo catalyst presents a higher dissolution rate in the NaCl medium than all synthesized catalysts. Furthermore, Ni-based composites showed improved durability due to a decrease in dissolution, and an increase in catalytic activity when using Nb 2 O 5 as the dispersed phase. The Ni(Nb 2 O 5 ) electrodes presented the higher catalytic activity in NaCl solution, even higher than that found in NiMo catalyst. • Different strategies for the synthesis of catalysts for the electrogeneration of H 2 in NaCl electrolyte are analysed. • NiMo catalyst presents higher dissolution in the NaCl medium than the composite synthesized catalysts. • The use of composites improves the catalyst durability, reducing the dissolution. • A remarkable increase of the current density was found when using the Ni(Nb 2 O 5 ) catalyst.

The Effectiveness Evaluation of Sacrificial Anode in Reinforced Concrete that has been Installed for One Year

Generally, reinforcing steel in concrete is protected from corrosion. This happens because the cement content in the concrete has an alkaline effect. It can reduce the risk of corrosion, but the reinforcing steel may still corrode if exposed to a corrosive environment. One method of providing a high protection value against corrosion is the sacrificial anode cathodic protection system. This study aims to evaluate the effectiveness of the sacrificial anode cathodic protection on reinforced concrete. Three types of specimens were used in the study. The specimens were (a) unconnected anode-cathode specimen, (b) connected anode-cathode (design 1), and (c) connected anode-cathode (design 2). The dimensions of the concrete specimen are 1000 mm in length, 100 mm in width, and 100 mm in height. Profometer 5+ was used to locate the reinforcing steel in the concrete. In this study, the condition of the protected criteria of reinforced concrete was achieved within 30 weeks in 2019 after wet-dry cycle treatment in 3.5% NaCl media, and thus, the specimen was exposed in an open air for one year. In 2020, all of the specimens were treated again with a wet-dry cycle for 3 weeks to measure the potential value of the reinforcing steel after a year. The measurement result of the corrosion potential value after one year showed that the specimen (c) had a potential value of -884.67 mV. While the specimen (b) had a potential value of -689 mV. These results show that the specimen (c) still within the protected criteria based on the NACE standard after one year of exposure, whereas the specimen (b) is no longer protected after one year of exposure.

Corrosion behaviour OF HVOF deposited Zn–Ni–Cu and Zn–Ni–Cu–TiB2 coatings on mild steel

Abstract In this study, Zn–Ni–Cu and Zn–Ni–Cu–TiB2 coatings were deposited using high-velocity oxy-fuel (HVOF) thermal spray technique on a mild steel substrate. Corrosion tests like neutral salt spray (NSS) following (ASTM B-117) standard and immersion cycle test following ASTM G-31, ASTM G1-03, standards were carried out for Zn–Ni–Cu and Zn–Ni–Cu–TiB2 coated mild steel along with uncoated mild steel acting as a control. Both Zn–Ni–Cu and Zn–Ni–Cu–TiB2 coated mild steel were corrosion resistant as compared to uncoated mild steel. Raman analysis following the immersion cycle test inferred that uncoated mild steel had all forms of rust. While Zn–Ni–Cu and Zn–Ni–Cu–TiB2 coated mild steel developed very little rust. The characterization helped to understand the changes in the surface before and after tests. It was observed that both Zn–Ni–Cu and Zn–Ni–Cu–TiB2 coated mild steel had little corrosion degradation of surface as compared to uncoated mild steel. Suggesting that both coatings performed significantly better compared to uncoated mild steel in corrosive environments. Polarization and EIS tests of both coated and uncoated mild steel in a 3.5% NaCl medium helped to understand the behaviour of coatings over a range of frequencies. Both coated samples had high polarization potential E corr values and lower polarization current I corr values as compared to uncoated mild steel. Inferring better performance of coatings in corrosive environments as compared to uncoated mild steel.

Rapeseed oil-based hippurate amide nanocomposite coating material for anticorrosive and antibacterial applications

Abstract Industrial crops and products have proved to be an excellent alternative to petro-based chemicals. Vegetable oils are rich in functional groups that can be transformed into monomers and polymers with applications such as biodiesel, lubricants, inks, coatings, and paints. This study describes the synthesis of rapeseed oil (RO)-based esteramide for the first time. The reaction was carried out by amidation of RO, producing diol fatty amide (N,N-bis(2-hydroxyethyl) RO fatty amide), followed by its esterification reaction with hippuric acid, resulting in RO-based hippurate amide (ROHA). Fourier-transform infrared spectroscopy and nuclear magnetic resonance confirmed the introduction of amide and ester moieties in ROHA. ROHA was further reinforced with silver nanoparticles (SNPs) to develop corrosion-protective nanocomposite coatings. ROHA/SNP coatings were scratch-resistant, impact-resistant, and flexible and showed good corrosion resistance performance toward 3.5 w/w% NaCl medium, with adequate corrosion protection efficiency, and antimicrobial behavior against Staphylococcus aureus, Chromobacterium violaceum, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans. ROHA/SNP coatings can be safely used up to 250°C.

Enhancing photoelectrochemical cathodic protection performance by facile tuning sulfur redox state in sacrificial agents

Photocathodic protection (PCP) performance is restricted by the photogenerated charges separation efficiency. This study reported a facile approach to enhance PCP performance. Na2S, Na2SO3, Na2S2O3, Na2SO4, and NaCl was selected as sacrificial agents, in which the PCP performance is characterized by coupling TiO2 and TiO2/ZnSe composites with 304 stainless steel. TiO2/ZnSe photoanode presented the best PCP performance in Na2S media. The maximum potential drop is 466.7 mV, which is about 3.5 times higher than that of in NaCl media. The corresponding photocurrent density is 270.7 μA/cm2, which is about 10 times higher than that of in NaCl media. Based on circle voltammetry and ultraviolet photo-electron spectroscopy characterization, it was found that the redox potential of the sacrificial reagent governs the migration and consumption of photogenerated holes of the photoanode.

Insight of development of two cured epoxy polymer composite coatings as highly protective efficiency for carbon steel in sodium chloride solution: DFT, RDF, FFV and MD approaches

• EP/AlA and EP/ArA present higher protective efficiency compared with 3.5% NaCl only. • 3D, AFM and SEM analysis showed that EP/AlA and EP/ArA act by chemisorption on the CS surface. • DFT, MDs, RDF, FFV and experimental data lead to investigate EP/AlA and EP/ArA as potential anticorrosive coating for CS in 3.5% NaCl medium. Cured epoxy polymers namely 3.3′-(phenylazanediyl) bis(1-((6-aminohexyl)amino)propan-2-ol) (EP/AlA) and 3.3′-(phenylazanediyl) bis(1-((4-(4-aminobenzyl)phenyl)amino)propan-2-ol) (EP/ArA) were used as potential protection coatings for carbon steel (CS) in 3.5% NaCl solution. The protection coatings of EP/AlA and EP/ArA on CS were investigated through, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization curves (PC), atomic force microscope (AFM), scaning electron microscopy (SEM), contact angle (CA), natural bond orbitals (NBO), frontier molecular orbitals (FMO), fractional free volume (FFV), radial distribution function (RDF) and molecular dynamics (MD) simulations. PC and EIS data indicated that the two cured epoxy polymers investigated have excellent protective efficiencies. Further, protective efficiencies of EP/ArA (92 and 94.6% for EIS and PC, respectively) are higher than that of EP/AlA (86.3 and 88.7% for EIS and PC, respectively) in 3.5 %NaCl solution. SEM and AFM results displayed the protective layer formed on CS coated through EP/AlA and EP/ArA could be stopped the chloride ions attack. Also, the quantum chemical analyzes of cured epoxy polymers EP/A1A and EP/ArA were employed at DFT/B3LYP/6-31G(d,p) level to appraise the reactivity behaviors and possible regions via using the FMO and NBO methods. The results disclosed that the dominant interactions for both molecules were determined as the resonance (n → Π* and Π → Π*) interactions. FFV value of EP/ArA film (20.22%) is lower than compared to EP/AlA (28.02%), due to the most condensed film by the EP/ArA on CS surface. Experimental results combined with theoretical approaches were used to investigate the proction coatings.

Corrosion inhibition of carboxylate substituted amidrazone on mild steel in 3% NaCl medium: Electrochemical, DFT and molecular dynamics simulation studies

The inhibitive effect of three synthesized amidrazone inhibitorsC6H4(2-COOH)NHN = C(COCH3)-NHC6H4(2-COOH) (1), C6H4(2-COOH)NHN = C(COCH3)-NHC6H5(2) and C6H5NHN = C(COCH3)-NHC6H4(2-COOH) (3)on mild steel in 3% NaCl solution at 25 ºC were evaluated by means of electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The X-ray show that two molecules of (1) isdimerize based on hydrogen bonding interactions. All experimental results demonstrate that these compounds are efficient inhibitors. The inhibition efficiencies(ηP%) increase with inhibitors concentration. At 1 × 10−4 M, the (ηP%) was 94.80%, 92.80% and 90.40% for 1, 2 and 3, respectively. The efficiency of inhibition is directly proportional to the concentration and the number of COOH on the amidrazone and inversely proportional to the temperature. Analysis of polarization curves showed that these compounds behaved as mixed-type inhibitors and their adsorption obeyed Langmuir model. Molecular dynamics and Quantum mechanical simulation approaches were utilized to rationalize the inhibition-efficiency of the investigated compounds.

Selective separation and recovery of selenium from copper anode slime by compound leaching followed by sulfate roasting

In this research, selenium was selectively separated and recovered from copper anode slime by a hydrometallurgical-pyrometallurgy union process. In the first compound leaching process with H2SO4, HCl and NaCl media, the pre-removal of As, Sb, and Bi was achieved, and the removal efficiencies were 85 %, 83 %, and 91 %, respectively. Selenium was effectively enriched by approximately 200 % after first compound leaching. Sulfate roasting method was used to selectively separate selenium in the second stage. In this study, more than 99.39 % of selenium was separated with concentrated sulfuric acid amount to first leaching residues ratio (H2SO4/ first compound leaching residues ratio) of 0.30 mL/g at 500 °C for 25 min, which enabled selenium to be selectively separated from the other elements. The kinetics of sulfation roasting of Se-enriched residues show that the selective separation of selenium conforms to the Avrami multiphase liquid–solid region reaction, the activation energy of the reaction is 28.118 kJ/mol, and the reaction efficiencies equation is k = 3.607e-3382/T, indicating that it is internal diffusion-controlled.

Comparative studies of three isatin-thiosemicarbazones against corrosion of AA6060 aluminum alloy exposed to acidic NaCl medium

Three isatin-thiosemicarbazone derivatives with different substituents (R) attached at C5 of the indolin-2-one ring, TSC-ISA-R (R = -H, -OCH3 and -OCF3), were synthesized and evaluated as medium-term corrosion inhibitors for AA6060 aluminum alloy exposed to acidic chloride medium. The inhibitory behavior and performance of TSC-ISA-R were investigated in relation to the molecular modification by field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization (PDP) analysis and weight loss measurement. Quantum chemical calculation and molecular dynamics (MD) simulation were further performed to study the inhibition behavior of the derivatives towards the corrosion of AA6060 alloy. Surface morphology analysis showed that TSC-ISA-OCH3 significantly mitigated the corrosion of the alloy while TSC-ISA-OCF3 had little inhibition effect. The inhibition efficiencies observed from weight loss measurements for TSC-ISA-H, TSC-ISA-OCH3 and TSC-ISA-OCF3 at 3 × 10–2 mM were 27.03%, 79.73% and 12.16%, respectively. PDP analysis indicated that both TSC-ISA-H and TSC-ISA-OCH3 were cathodic type inhibitors and TSC-ISA-OCF3 was a mixed-type one primarily hindering the cathodic reactions of AA6060 alloy. The results of EDS and XPS revealed that TSC-ISA-R molecules were adsorbed on the alloy surface, and the adsorption was closely correlated with the substituent modification. The theoretical results obtained from quantum chemical calculations and MD simulations for the protonated TSC-ISA-R correlated well with their ranking of the experimental inhibition efficiencies. The substituent effects of -R were proposed to significantly affect the electron densities on para-amino N1 and exocyclic imino-N2 atoms of TSC-ISA-R capturing H+ in the medium, and thereby probably underlay their differences in the inhibition behavior and performance.

The role of acetylacetone in alkaline surface modification bath of electro-galvanized steel to enhance protective functioning of a hybrid silane coating

The current work outlines the impact of acetylacetone (AcAc) in the alkaline surface treatment bath on durability and the anti-corrosion properties of electro-galvanized steel (EGS) coated with a hybrid silane composition. The surface characteristics of the EGS samples before and after modifications were appraised using atomic force microscopy, field emission scanning electron microscopy, and contact angle measurements confirming the changes in roughness, morphology and wettability properties imposed by surface treatments. To elucidate the chemical composition of the protecting layer developed on the surface of EGS, X-ray photoelectron spectroscopy was utilized which evidently endorsed forming a film consisting of zinc hydroxide, zinc oxide, and zinc acetylacetonate. The corrosion resistance of the specimens during immersion in 3.5 % NaCl medium was determined using electrochemical impedance spectroscopy and polarization experiments. The low-frequency impedance (at 0.01 Hz) of silane-coated samples modified in the optimal condition (0.5 M NaOH bath) in the presence and absence of AcAc was respectively ca. 15,900, 5800 Ω·cm2. The electrochemical results corroborated the overriding role of a trace amount of AcAc in the corrosion protection of silane-coated EGS samples. The novel surface treatment proposed in this work provides improved corrosion protection of silane coating on EGS having the lowest icorr and presenting inhibition efficiency of 74 % in polarization experiment.

Physiological Measurements and Transcriptome Survey Reveal How Semi-mangrove Clerodendrum inerme Tolerates Saline Adversity.

Salinity adversity has been a major environmental stressor for plant growth and reproduction worldwide. Semi-mangrove Clerodendrum inerme, a naturally salt-tolerant plant, can be studied as a successful example to understand the biological mechanism of saline resistance. Since it is a sophisticated and all-round scale process for plants to react to stress, our greenhouse study interpreted the response of C. inerme to salt challenge in the following aspects: morphology, osmotic protectants, ROS production and scavenging, ion homeostasis, photosynthetic efficiency, and transcriptome reprogramming. The results drew an overview picture to illustrate the tolerant performance of C. inerme from salt acclimatization (till medium NaCl level, 0.3 mol/L) to salinity stress (high NaCl level, 0.5 mol/L). The overall evaluation leads to a conclusion that the main survival strategy of C. inerme is globally reshaping metabolic and ion profiles to adapt to saline adversity. These findings uncover the defense mechanism by which C. inerme moderates its development rate to resist the short- and long-term salt adversity, along with rebalancing the energy allocation between growth and stress tolerance.

Bacillus arachidis sp. nov., Isolated from Peanut Rhizosphere Soil.

A novel facultatively aerobic bacterium designated SY8 was isolated from a peanut rhizosphere soil sample collected in Jiangsu Province, China. Cells are Gram-stain-positive, rod-shaped, and agar colonies are creamy, opaque, and usually rhizoidal. Strain growth occurs at 30 - 45°C (optimum 30°C), pH 4.0 - 10.0 (optimum pH 6.0) and 0 - 4% (w/v) NaCl (optimum 2%) in Luria-Bertani medium. Phylogenetic analysis of the 16S rRNA gene sequences indicated that strain SY8 forms a distinct lineage in the clade of genus Bacillus and is related to Bacillus pseudomycoides DSM 12442T (99.9%). Phylogenetic analysis of the concatenated gene sequences of 16S rRNA, gryB and rpoD also indicated that strain SY8 forms a distinct lineage in Bacillus. Calculation of the average nucleotide identities and the digital DNA-DNA hybridization values between strain SY8 and the related type Bacillus strains further revealed that strain SY8 represents a distinct species. The predominant cellular fatty acids are iso C15:0 (28.7%) and summed feature 3 (C16:1ω7c and/or C16:1ω6c) (10.3%). The major polar lipids consisted of diphosphatidyl glycerol, phosphatidyl glycerol, phosphatidyl ethanolamine, phosphatidylinositol, and three unidentified phospholipids. The major menaquinone of SY8 was MK-7. Based on phenotypic, phylogenetic, chemotaxonomic, and genomic features, strain SY8 represents a novel species of the genus Bacillus. The name Bacillus arachidis sp. nov. is proposed with strain SY8T (= CCTCC AB 2021100T=LMG 32409T) designated as the type strain.