NaCl Solutions Of Different Concentrations Research Articles

Synthesis of MnFe2O4 Spinel on Rusted Q235 Steel Surface and Its Corrosion Resistance Properties.

Corrosion of steel is an issue that cannot be ignored in contemporary society. Due to large-scale corrosion, it is urgent to develop a surface treatment process that enhances the corrosion resistance of steel, allowing for application in various scenarios as needed. This study aims to investigate a novel surface treatment process to extend the service life of corroded Q235 steel, reduce its sensitivity to corrosion, and enable its use in multiple environments. This study employs the sol-gel method, using manganese nitrate solutions of varying concentrations to treat the surface of Q235 steel after different electrolysis times. The optimal conditions for precursor preparation were found to be a Mn2+ concentration of 0.1 mol/L and an electrolysis time of 2 h. Electrochemical tests using NaCl solutions of different concentrations revealed a significant reduction in the corrosion current for the composite coating based on Q235 steel treated with this method in NaCl solutions with wt.% = 1, 2, 3, 4, 5. Furthermore, the resistance to corrosion was strongest in the NaCl solution with a concentration of 1 wt.% where the corrosion current decreased from 24.8 µA/cm2 to 6.79 µA/cm2. Additionally, the coating was found to be diffusion-controlled in the early stages of the corrosion process and charge transfer-controlled in the later stages. The MnFe2O4 spinel coating demonstrated the greatest enhancement in corrosion resistance in the wt.% = 1 NaCl solution.

Identification of genetic loci for salt tolerance in Brassica napus at the germination stage using a genome-wide association study

Brassica napus is a leading crop used to repair and utilize saline-alkali land. Cultivating salt-tolerant varieties of B. napus is therefore an effective means of increasing the productivity of saline-alkali land. However, the molecular regulation of salt tolerance during germination in B. napus is still unclear. In this study, seeds from an association panel containing 202 diverse accessions were treated with different concentrations of NaCl solution (200, 250, and 300 mM), and their relative germination rates (RGRs) were calculated on Days 3 and 7 after treatment. Based on phenotypic data obtained over six experiments, a total of 2749 single nucleotide polymorphisms (SNPs) significantly related to RGR were identified using a genome-wide association study (GWAS) analysis, and eight candidate genes were identified in candidate intervals. The RGR of seeds treated with 250 mM NaCl for 7 days was identified as a useful index of salt tolerance in B. napus, and 10 accessions with RGRs of 90–98 % were screened as excellent salt-tolerant germplasm resources. Finally, two of the identified SNPs were designed as SNP markers to screen salt-tolerant germplasm resources. These results provide a theoretical basis on which to determine the molecular mechanism of salt tolerance in B. napus at the germination stage.

The Effects of Mother Tree Size and Flowering Period on Salt Tolerance of <i>Tamarix Austromongolica</i> Seeds in the Yellow River Delta

<i>Tamarix austromongolic</i>a is a two-season flowering plant with a spring and summer flowering period and both flowering periods produce viable seeds, with flowering extending from mid-May to October and seed maturation from mid-June to October. In order to reveal the germination pattern of <i>T. austromongolica</i> seeds in the Yellow River Delta region, this study investigated the salt tolerance of seeds of different age mother trees during the spring and summer flowering periods in the region. Spring and summer flowering seeds of different ground diameter mother trees in the <i>T. austromongolica</i> forest in the region were collected and subjected to seed germination experiments under different concentrations of NaCl solution. The results showed that the diameter grade of the mother tree had a significant impact on seed germination, but had no significant effect on early seedling growth (except for the root length of offspring seedlings during the summer flowering period). As the diameter level of the mother tree increases, the germination rate, germination index, and vitality index of seeds during the spring flowering period first increase and then decrease, with the highest values observed at a ground diameter of 10.0-19.9cm. However, the above indicators of summer flowering seeds gradually decreased with the diameter increasing. There were significant differences in salt tolerance of seeds during different flowering periods. The germination rate and germination index of spring flowering seeds significantly decreased between 11‰ and 15‰, but the effect of salt concentration on summer flowering seed germination was not significant. For the early growth of seedlings, as the salt concentration increased, the root length and seedling height of seed offspring seedlings during spring and summer flowering periods decreased after being higher than 5‰. Compared with spring flowering seeds, summer flowering seeds had higher germination ability and seedling weight under salt stress. Therefore, the salt tolerance of the seeds of <i>T. austromongolica</i> was determined by the size of the mother tree and the flowering period, which is an important strategy for its adaptation to the Yellow River Delta region.

Effect of Varied NaCl Soaking Treatment on Chemical Composition of Lesser Yam Flour and Its Use in the Production of Gluten-Free Noodles

In order to reduce dependence on wheat flour, it was necessary to use alternative options, such as lesser yam flour. The production of lesser yam flour consisted of soaking yam tubers in NaCl solutions of different concentrations (20% and 25%). This soaking process was necessary for enhancing the physical characteristics of the flour, resulting in reduced mucus and a whiter appearance. The diverse NaCl concentrations during soaking significantly affected chemical composition of lesser yam flour, impacting parameters, including moisture, ash, fat, total protein, reducing sugar, total sugar, glucomannan content, and calories. However, no discernible effect was observed on the crude fiber and carbohydrate content. In comparison to the 25% NaCl, the 20% NaCl had lesser yam flour with lower moisture, ash, protein, total sugar, and reducing sugar content, but higher fat, glucomannan, and calories. The 25% NaCl soaked lesser yam flour was selected for the production of gluten-free dry noodles. Dry noodles were prepared with various proportions of lesser yam flour and mocaf flour, including 0:100 (TG0), 50:50 (TG1), 50:40 (TG2), 70:30 (TG3), 80:20 (TG4), and 90:10 (TG5). An increase in the proportions of lesser yam flour resulted in increased hardness and chewiness, along with decreased springiness and cohesiveness. Therefore, lesser yam could be processed into flour by soaking in NaCl solutions to produce better flour, with the optimal flour composition being 80% lesser yam flour and 20% mocaf flour for gluten-free noodles production. This suggested the potential for further development of lesser yam flour as a raw material for the production of gluten-free noodles.

Identification and Evaluation of Celery Germplasm Resources for Salt Tolerance

This study evaluated the salt tolerance in 40 celery germplasm resources to clarify the different salt tolerances of celery germplasm. A gradient treatment with different concentrations of NaCl solutions (100, 200, and 300 mmol·L−1) was used to simulate salt stress. After 15 days of salt treatment, 14 indicators related to plant growth, physiology, and biochemistry were determined. The results showed that different celery varieties responded differently to salt stress. Notably, there were significant variations in below-ground dry weight, root–crown ratio, antioxidant enzyme activity, and soluble protein content among the accessions under salt stress. Principal component analysis was used to identify important indices for evaluating salt tolerance, including plant height, spread, content of soluble protein, and so on. A comprehensive evaluation was conducted utilizing the salt damage index, principal component analysis, affiliation function analysis, and cluster analysis. The 40 celery germplasms were classified into five highly salt-tolerant, seven salt-tolerant, fifteen moderately salt-tolerant, nine salt-sensitive, and four highly salt-sensitive germplasms. SHHXQ, MXKQ, XBQC, XQ, and TGCXBQ were highly salt-tolerant germplasms, and BFMSGQ, HNXQ, ZQ, and MGXQW were highly salt-sensitive germplasms. The results of this study provide a reference for the variety of celery cultivation in saline areas and lay a foundation for the selection and breeding of salt-tolerant varieties of celery.

Effect of chloride salt migration at interfaces on asphalt-aggregate adhesion: A molecular dynamics study

Asphalt pavements can be damaged by moisture and salt, and the bond strength between asphalt and aggregate is related to the erosion of the salt solution. In this study, considering the migration and diffusion of the solution at the interface, a molecular dynamics modeling method was used to simulate the process where the salt solution erodes the asphalt-aggregate interface, and results show that the solution invades the asphalt-aggregate interface, gradually squeezing the asphalt away from the aggregate surface in a wedge shape, and the interaction force between the asphalt and the aggregate is gradually reduced to 0. The diffusion rate of the solution at the interface is related to the position of the solution. If the solution is farther away from the aggregate, it will be less restricted by the aggregate. NaCl affects the diffusion of water molecules. The greater the concentration of NaCl solution, the lower the height of the wedge formed by the solution at the interface. Compared to quartz, calcite has a stronger limiting effect on the solution, which is manifested by a greater resistance to water damage. Under the attraction of NaCl solution, the polar components are more likely to move toward the solution surface, while the less polar components show different distribution and diffusion states. In this study, we observed the conformational changes in the erosion process of different concentrations of NaCl solutions and calculated the change rule of interaction force, which helps understand the erosion process of salt solutions and provides a new idea for the study of chloride on asphalt pavement spalling.

Influence of Concentration Gradients on Electroconvection at a Cation-Exchange Membrane Surface.

Membrane-based systems, such as electrodialysis, play an important role in desalination and industrial separation processes. Electrodialysis uses alternating anion- and cation-exchange membranes with a perpendicular electric field to generate concentrated and diluate streams from a feed solution. It is known that under overlimiting current conditions, reduced charge and mass transfer at the membrane interface leads to regions of high ion depletion generating instability and vortices termed electroconvection. While electroconvective mixing is known to directly impact the separation efficiency of electrodialysis, the influence of ion concentration gradients across the membrane experienced in a functional electrodialysis system is not known. Here, we report the influence of ion concentration gradients across a cation exchange membrane (Nafion) that is both aligned with and opposed to the applied electric field. Experiments were conducted by coflowing NaCl solutions of different concentrations (0.1-100 mM) on each side of the membrane, and electroconvection was visualized with a fluorescence dye (Rhodamine 6G). We obtained concentration profiles from fluorescence image data and systematically measured the thickness of the depletion boundary layer dBL under different conditions. We found smaller dBL values at a higher flow rate both with and without concentration gradients. Our results show that electroconvection is enhanced when the electric field is opposite to the direction of the concentration gradient.

Use of Cryopreserved Sperm of Grass Carp (Ctenopharyngodon idella) for Seed Production at the Hatchery Level of Bangladesh-A Need for Development of Germplasm Repositories.

Grass carp (Ctenopharyngodon idella), a freshwater nonnative fish species, is a potential aquaculture candidate in Bangladesh. The seed of the species is produced in the hatcheries by hypophysation, but the quality of seedstock of grass carp is deteriorated due to inbreeding, negative selection, and interspecific introgression among fishes. To increase the availability of quality seed and best genetic traits of grass carp, this study dealt with finding suitable conditions of sperm cryopreservation protocols and evaluated the effectiveness of cryopreserved sperm through breeding trials of C. idella. A broodstock population was developed from fingerlings imported from China by the Bangladesh Department of Fisheries. Sperm was collected from hormone-induced mature males, with an estimated concentration of 2.4 ± 0.3 × 1010 cells/mL and a pH of 8.3 ± 0.2. Sperm motility was evaluated in different concentrations of NaCl solution. The highest motility (96% ± 1%) and longest motility duration (22 ± 1 min) were achieved at 0.4% of NaCl (128 mOsmol/kg). The toxicity of DMSO and methanol at concentrations of 5%, 10%, and 15% was evaluated for 5-40 min using Alsever's solution and egg yolk citrate. The highest motility was achieved during 5 and 10 min of incubation with cryoprotectants at 5% and 10%. Alsever's solution with 10% DMSO at 1:9 dilution with sperm produced the highest equilibration motility (93% ± 2%) and when cooled at 10°C/min yielded the highest postthaw motility (85% ± 3%). Fertilization of 24% ± 3% to 51% ± 2% and hatching of 18% ± 2% to 41% ± 2% were achieved by using cryopreserved sperm in six selected private hatcheries. The fertilization rate for fresh sperm sourced from hatchery-reared males was 64% ± 5% to 85% ± 3%, and the hatching rate ranged from 53% ± 6% to 74% ± 5%. Thus, the cryopreservation protocol of C. idella sperm was found to be feasible for fry production at commercial hatcheries, but further research is needed to improve the fertilization and hatching rates.

Novel technique for measuring salt concentrations in food using silver dichromate

Curing with salt reduces water content in food and extends its shelf life; therefore, understanding salt permeability in food is critical to food quality and safety. Although there are many new techniques to measure salt concentrations in food, they cannot be applied in practice owing to drawbacks such as the need for expensive equipment or the inability to image quickly; therefore, development of a fast and simple measurement method is crucial. Silver dichromate is converted to silver chloride when it encounters chloride ions. Based on this principle, we soaked radishes in NaCl solutions of different concentrations and added a layer of silver dichromate to it. Salt concentrations was observed in 5 min, as areas with NaCl concentration of ≥1 % appeared white, whereas the other regions appeared red. A strong correlation (r = 0.94/0.96) was observed between the area of salt concentrations measured using this method and that measured using the conventional salt measurement method, demonstrating the reliability of the method. This method will help advance research related to salt concentrations in food and its application in industrial scenarios.

Влияние воздействий поверхностно-активных веществ на прочность образцов мерзлых вскрышных горных пород угольных месторождений криолитозоны

The harsh climatic conditions of the cryolithic zone with its long winter period and presence of permafrost soils significantly slow down all technological processes in surface mining. The resistance of frozen rocks at coal mines to digging with mining equipment can be reduced by their preliminary softening with the use of surfactants. The paper discusses the softening effect of aqueous surfactant solutions on samples of frozen overburden rocks. The authors demonstrate that treatment of rocks with solutions of optimal composition and concentration decreases their strength, which makes it possible to enhance the efficiency of In-Pit Crushing and Conveying Systems based on the rotary mechanical shovel in combination with a conveyor as well as the use of continuous miners. Experimental data are presented on the strength properties of artificially made samples of overburden rocks from the Kangalassky coal deposit saturated with surfactant solutions of different concentrations. The authors point out that the highest decrease in the samples strength is achieved when using aqueous solution of aluminum chloride. The results of experiments carried out to establish the effects of distilled water (H2O) and NaCl solutions of different concentrations on the strength properties of fine-grained sandstones from the Elga coal deposit are presented, which confirm that at the temperature of -10°С the maximum reduction of up to 55% is achieved in the strength of the samples, and when the temperature decreases from -10°С to -20°С a slight increase is observed in the sample strength. The authors suggest that the use of surfactants will reduce the strength of the frozen overburden soils, thus making it possible to apply a blast-free mining technology.

Ciprofloxacin adsorption performance of Co‐doped UiO‐66

The presence of ciprofloxacin in various water sources, even at low concentrations, causes health risks and serious environmental pollution as well as development of antibiotic resistance. So, it is critically necessary to remove ciprofloxacin effectively from the effluent. Co‐doped UiO‐66 was synthesized through one‐step hydrothermal method and evaluated as an adsorbent for ciprofloxacin adsorption. Ciprofloxacin adsorption was systematically investigated revealing adsorption isotherms, kinetics, and thermodynamics. The findings revealed that Freundlich isotherm model (maximum adsorption capacity: 45.17 mg g−1) at optimum experimental conditions (pH: 5, contact time: 90 min and adsorbent dosage: 0.3 g L−1) and acquired data were fitted using pseudo‐second‐order kinetic model. The ciprofloxacin adsorption was determined to be a spontaneous and endothermic from thermodynamic experiments. Effects of coexisting compound in the aqueous solutions on the Co‐doped UiO‐66 adsorption performance were studied using different concentrations of NaCl solution. The ciprofloxacin removal slightly decreased in the case of increasing the concentrations of Na+ ions. Regeneration of the Co‐doped UiO‐66 was carried out in methanol + acetic acid solution and repeated adsorption experiments were conducted to reveal reusability of the Co‐doped UiO‐66. Its ciprofloxacin adsorption capacity reduced to 38.0 mg g−1 after the four cycles indicating that the Co‐doped UiO‐66 was a reusable and potential adsorbent for ciprofloxacin adsorption process.

Study on the difference of high frequency dielectric properties of biological tissues measured by air and packed coaxial probe

In this paper, the differences between air probe and filled probe for measuring high-frequency dielectric properties of biological tissues are investigated based on the equivalent circuit model to provide a reference for the methodology of high-frequency measurement of biological tissue dielectric properties. Two types of probes were used to measure different concentrations of NaCl solution in the frequency band of 100 MHz-2 GHz. The results showed that the accuracy and reliability of the calculated results of the air probe were lower than that of the filled probe, especially the dielectric coefficient of the measured material, and the higher the concentration of NaCl solution, the higher the error. By laminating the probe terminal, liquid intrusion could be prevented, to a certain extent, to improve the accuracy of measurement. However, as the frequency decreased, the influence of the film on the measurement increased and the measurement accuracy decreased. The results of the study show that the air probe, despite its simple dimensional design and easy calibration, differs from the conventional equivalent circuit model in actual measurements, and the model needs to be re-corrected for actual use. The filled probe matches the equivalent circuit model better, and therefore has better measurement accuracy and reliability.

Strength and Microscopic Characteristics of Slag-Based Geopolymer-Solidified Sludge after Dry–Wet Cycling with Chloride Salt Solutions

As a new type of green soil-curing agent, geopolymers have the advantages of high strength, good durability, and low carbon emissions, and slag is widely used as a common geopolymer precursor in geopolymer production. Therefore, it is important to investigate the strength and durability of slag-based polymer-solidified sludge under the action of dry–wet cycling with chloride salt solutions. After curing the slag-based polymer-solidified sludge with NaOH (NO), Na2SiO3 (NS), and calcium carbide slag (CS) as alkali excitants to different curing ages (7, 14, 28 days), experiments involving different numbers of dry–wet cycles (0, 5, 10, 20, 30) with NaCl solutions of different concentrations (0%, 5%, 10%) were performed to investigate the unconfined compressive strength and micromorphology of the solidified sludge after undergoing dry–wet cycling. The test results showed that the strength of sludge cured with NO for 7 and 14 days showed a trend of increasing and then decreasing with an increasing number of dry–wet cycles, and the strength of sludge cured with NO for 28 days showed a trend of gradually decreasing with an increasing number of dry–wet cycles. The order of the resistance of sludge cured with the three excitants to the effect of the dry–wet cycles of chlorine salt was CS > NO > NS. After the dry–wet cycling, small cracks appeared on the surface of the NS-cured soil, the surface of the NO-cured soil was intact, and a small amount of surface peeling was observed for the CS-cured soil. Scanning electron microscopy test results showed that the chloride salt dry–wet cycles caused the formation of pores and cracks in the soil, and NaCl crystallization and Friedel’s salt production were observed in the soil, thus reducing the strength of the solidified sludge.

Synthesis of Poly (2-Acrylamido-2-methylpropanesulfnoinc Salt) Modified Carbon Spheres.

The paper reports a facile synthesis of novel anionic spherical polymer brushes which was based on grafting sodium 2-acrylamido-2-methylpropane-1-sulfonate from the surface of 4,4'-Azobis (4-cyanopentanoyl chloride)-modified carbon spheres. Various characterization methods involving a scanning electron microscope, energy dispersive X-ray spectroscopy, Fourier transform infrared spectrum, and thermo-gravimetric analysis were utilized to analyze the morphology, chemical composition, bonding structure, and thermal stability, respectively. The molecular weight (Mw) and polydispersity (Mw/Mn) of brushes were 616,000 g/mol and 1.72 determined by gel permeation chromatography experiments. Moreover, the dispersibility of ASPB in water and in the presence of aqueous NaCl solutions of different concentrations was investigated. Results show that the dispersibility of carbon spheres has been enhanced owing to grafted polyelectrolyte chains, while the zeta potential of the particle decreases and its brush layer shrinks upon exposure to sodium ions (Na+).

Moderate Salinity Stress Increases the Seedling Biomass in Oilseed Rape (Brassica napus L.).

Oilseed rape (Brassica napus L.), an important oil crop of the world, suffers various abiotic stresses including salinity stress during the growth stage. While most of the previous studies paid attention to the adverse effects of high salinity stress on plant growth and development, as well as their underlying physiological and molecular mechanisms, less attention was paid to the effects of moderate or low salinity stress. In this study, we first tested the effects of different concentrations of NaCl solution on the seedling growth performance of two oilseed rape varieties (CH336, a semi-winter type, and Bruttor, a spring type) in pot cultures. We found that moderate salt concentrations (25 and 50 mmol L-1 NaCl) can stimulate seedling growth by a significant increase (10~20%, compared to controls) in both above- and underground biomasses, as estimated at the early flowering stage. We then performed RNA-seq analyses of shoot apical meristems (SAMs) from six-leaf-aged seedlings under control (CK), low (LS, 25 mmol L-1), and high (HS, 180 mmol L-1) salinity treatments in the two varieties. The GO and KEGG enrichment analyses of differentially expressed genes (DEGs) demonstrated that such a stimulating effect on seedling growth by low salinity stress may be caused by a more efficient capacity for photosynthesis as compensation, accompanied by a reduced energy loss for the biosynthesis of secondary metabolites and redirecting of energy to biomass formation. Our study provides a new perspective on the cultivation of oilseed rape in saline regions and new insights into the molecular mechanisms of salt tolerance in Brassica crops. The candidate genes identified in this study can serve as targets for molecular breeding selection and genetic engineering toward enhancing salt tolerance in B. napus.

Study on the effective measurement area of an open-ended coaxial probe for the dielectric measurement of biological tissues.

The dielectric properties of tissues are very important physical factors for the investigation and application of bio-electromagnetism. However, the size of the active sample tissue is usually limited in actual measurement, making it difficult to meet the requirements of the existing high-frequency measurement methods, thus influencing the measurement results. The present study aimed to systematically investigate the various factors influencing the effective measurement area of the open-ended coaxial probe, including the design size of the probe and the dielectric properties of the object to be measured. The simplified material mixing model, in which several types of materials were set as the material under test (MUT) and the perfect conductor (PEC) was set as the specific material, was used in the simulation to study the effective measurement area of eight types of probes with different sizes for the dielectric measurement of different MUTs. Different concentrations of NaCl solutions and three types of coaxial probes were used in the actual measurement to verify the simulation results. According to the simulation results, the effective measurement area, especially the effective measurement radius, was closely related to the outer conductor radius of the probe. The effective measurement area of the probe decreased when the outer conductor radius of the probe reduced. Moreover, the change in the effective measurement area of the probe was independent of the MUT when the cross-sectional size of the probe was smaller than a certain threshold value. The experimental results also confirmed this conclusion. According to the research results, the independent variable dimension could be effectively reduced and the modeling difficulty was reduced when the analysis model of the effective measurement area of the probe was established.

Physiological and Biochemical Characteristics and Response Patterns of Salinity Stress Responsive Genes (SSRGs) in Wild Quinoa (Chenopodium quinoa L.)

Cultivating salt-tolerant crops is a feasible way to effectively utilize saline-alkali land and solve the problem of underutilization of saline soils. Quinoa, a protein-comprehensive cereal in the plant kingdom, is an exceptional crop in terms of salt stress tolerance level. It seems an excellent model for the exploration of salt-tolerance mechanisms and cultivation of salt-tolerant germplasms. In this study, the seeds and seedlings of the quinoa cultivar Shelly were treated with different concentrations of NaCl solution. The physiological, biochemical characteristics and agronomic traits were investigated, and the response patterns of three salt stress-responsive genes (SSRGs) in quinoa were determined by real-time PCR. The optimum level of stress tolerance of quinoa cultivar Shelly was found in the range of 250–350 mM concentration of NaCl. Salt stress significantly induced expression of superoxide dismutase (SOD), peroxidase (POD), and particularly betaine aldehyde dehydrogenase (BADH). BADH was discovered to be more sensitive to salt stress and played an important role in the salt stress tolerance of quinoa seedlings, particularly at high NaCl concentrations, as it displayed upregulation until 24 h under 100 mM salt treatment. Moreover, it showed upregulation until 12 h under 250 mM salt stress. Taken together, these results suggest that BADH played an essential role in the salt-tolerance mechanism of quinoa. Based on the expression level and prompt response induced by NaCl, we suggest that the BADH can be considered as a molecular marker for screening salt-tolerant quinoa germplasm at the early stages of crop development. Salt treatment at different plant ontogeny or at different concentrations had a significant impact on quinoa growth. Therefore, an appropriate treatment approach needs to be chosen rationally in the process of screening salt-tolerant quinoa germplasm, which is useful to the utilization of saline soils. Our study provides a fundamental information to deepen knowledge of the salt tolerance mechanism of quinoa for the development of salt-tolerant germplasm in crop breeding programs.

The Corrosion Behavior of Al-Cu-Li Alloy in NaCl Solution

Al-Cu-Li alloys are widely used in aerospace due to their excellent mechanical properties. However, the surface of Al-Cu-Li alloy components is prone to localized corrosion, when it serves in humid environments such as the ocean, due to the action of moisture in the air and Cl− in the atmosphere. Therefore, it is significant to study the corrosion performance of typical third-generation Al-Cu-Li alloys in a marine environment. The corrosion tests of the experimental materials are carried out in different concentrations of NaCl solution, and their morphology and maximum corrosion depth are characterized to evaluate their corrosion resistance at a particular time. The corrosion behavior of the third generation typical Al-Cu-Li alloys (2A97-T3, 2A97-T6, 2060-T8, and 2099-T83) and high-strength Al alloy 2024-T4 in solution containing Cl− is investigated using correlative immersion testing. The results show that 2A97-T3 possesses the best corrosion resistance performance of all under the same concentration of NaCl solution and soaking time. The corrosion resistance performance of 2024-T4 is respectively stronger than that of 2060-T8 and 2099-T83, but weaker than that of 2A97 (T3, T6). The corrosion morphologies of 2060-T8 and 2099-T83 are characterized by deep pits and large areas of exfoliation corrosion, while the corrosion morphology of 2099-T83 is the worst, indicating that its corrosion resistance is the weakest of all. The local corrosion preferentially occurred in the boundary region between intermetallic compounds or precipitates and alloy matrix in NaCl solution, and the lithium is selectively dissolved during the dissolution process, which brings about the enrichment of copper-containing residues. Subsequently, the copper-rich residue serves as the cathodic relative to the Al matrix, which leads to the anodic dissolution of the peripheral Al matrix occurs.

The Association Between Salt Taste Threshold and Hypertensive Nephropathy in Patients With Essential Hypertension

Abstract Background To investigate the relationship between salt taste threshold and hypertensive nephropathy in patients with essential hypertension. Methods A cross-sectional study was conducted in 346 hypertensive patients in Daping Hospital from 2017 to 2019. Among them 94 patients were hypertensive nephropathy and 252 hypertensive patients without renal damage served as controls. The salt taste threshold of patients was measured by taking different concentrations of NaCl solution. The difference in salt taste threshold between the 2 groups of patients was compared, and the correlation between salt taste threshold and hypertensive nephropathy was analyzed. Receiver operating characteristic (ROC) curve was used to analyze the value of salt taste threshold to predict hypertensive nephropathy. Results The salt taste threshold of the hypertensive nephropathy patients was significantly higher than that in hypertensive patients without renal damage [0.075 (0.050–0.100) vs. 0.050 (0.050–0.100) mol/l, P = 0.010]. As salt taste threshold increased, the renal function decreased gradually, which was manifested by the increase of urine microalbumin to creatinine ratio, blood creatinine, blood urea nitrogen, urine N-acetyl-β-glucosaminidase, and the decrease of estimated glomerular filtration rate. Logistic regression analysis showed that after adjusting for traditional risk factors, a higher salt taste threshold was an independent risk factor for hypertensive nephropathy (odds ratio = 1.299, 95% confidence interval [CI] 1.020–1.655, P = 0.034). The area under ROC curve was 0.586 (95% CI 0.520–0.652). Conclusions Salt taste threshold correlates with biochemical indicators of renal damage, and a higher salt taste threshold is a risk factor of hypertensive nephropathy in patients with essential hypertension.

Propagule limitation affects the response of soil methane oxidizer community to increased salinity

The extent to which propagule limitation can govern the responses of microbially-mediated processes (such as methane oxidation) to sudden environmental changes, is poorly understood. Here, we compared the ability of the methanotroph community in lakeshore soils of two lakes to respond to an experimental increase in salinity. One set of samples was taken from lakeshore soils of a freshwater lake (Yang Lake), the other from a slightly brackish lake (Qinghai Lake), both on the Tibetan Plateau. Samples were incubated in microcosms by adding ∼ 5 % 13CH4 or 12CH4 and different concentrations of NaCl solution. DNA stable-isotope probing (DNA-SIP) followed by high-throughput sequencing was used to determine how the active methanotrophic populations differed in lakeshore soils with different salinity levels. Samples from saline and freshwater lake initially showed much-reduced methane oxidation ability and methanotrophic activity at increased salinity. For the freshwater samples with the salinity of 25 to 50 g/L after NaCl addition, there was no adaptation and increase in methanotrophy after 7 days. By contrast, samples from the brackish lake showed an initial depression of methane oxidation, followed by greatly increased rates after several days. Sequencing revealed that this recovery of methanotrophy in the brackish lake samples was associated with a major switchover in composition of active methanotroph community. In particular, the relative abundance of Type Ⅰa methanotrophs became more abundant at increased salinity. It appears that in this freshwater lake environment, isolation from any nearby high-salinity-tolerant bacterial sources has prevented the possibility of full adaptation to a high salinity change in the environment, and only a moderate salinity adaptation is possible by species-sorting from within the existing community. By contrast, in the higher-salinity environment, the highly salinity-tolerant Methylomicrobium was able to break the establishment limitation in the high salinity environment and become the dominant methanotroph. Our study provides an instance of propagule limitation preventing adaptation to changed conditions.