Decrease In Electrical Conductivity Research Articles

Coupling Effect of Mn Addition and Deformation on Mechanical and Electrical Properties of Al-Zr Alloys

In order to increase the strength of Al-Zr alloys, which are promisingly used for heat-resistant conductors, the coupling effect of Mn addition (0.16 wt.% and 0.88 wt.%) and deformation on the precipitation, mechanical, and electrical properties of an Al-0.18wt.% Zr alloy was studied using transmission electron microscopy (TEM), atom probe tomography (APT), hardness testing, and electrical conductivity measurement, respectively. Results showed that the Mn addition fully suppresses the Al3Zr precipitation in both hot-deformed and undeformed cases, which is mainly due to a strong Mn-vacancy bonding, in which Mn atoms seize vacancies and hence reduce the available vacancies for Al3Zr nucleation. Minor 0.16 wt.% Mn addition causes a simultaneous decrease in hardness and electrical conductivity, regardless of whether there is deformation. The higher 0.88 wt.% Mn addition, however, significantly increases the hardness by over 40%, especially in combination with deformation. Possible influencing factors such as grain size, dislocations, intergranular/intragranular precipitation, and solute clusters are comparatively discussed in terms of microstructural features and mechanical/electrical properties that are tuned by Mn addition and/or deformation. It is found that the Mn addition can make remarkable contributions to the hardness and thermal stability of the Al-Zr alloys when coupled with deformation.

Influência do ciclo hidrológico sobre a abundância de desmídias em uma lagoa rasa de planície de inundação do semiárido brasileiro

Abstract Aim Knowledge of hydrological characteristics is essential for understanding ecological processes in floodplains, which can support sustainable management. We evaluated environmental variations in a shallow floodplain lagoon located in the Chapada Diamantina, Andaraí, Bahia. We aim to identify phases of the hydrologic cycle and their influence on desmid density, which is a group of algae known for its potential as bioindicator of trophic changes. Methods Bimonthly samplings were performed at four points in the lagoon. Abiotic (temperature, conductivity, pH, transparency, depth, dissolved oxygen, total and dissolved nutrients) and biotic (macrophyte cover, phytoplankton chlorophyll-a, and desmid density) variables were determined. The Trophic State Index (TSI) was calculated based on phytoplankton chlorophyll-a, and total phosphorus concentration. Results The lagoon was characterized by well-oxygenated, slightly acidic waters with low electrical conductivity. According to the TSI, the lagoon varied from mesotrophic to hypereutrophic during the study period. The driest months (August and October) were marked by high water transparency, low depth, nitrogen concentration, and macrophyte coverage. The highest value of accumulated precipitation was registered in December, when there was an increase in depth and a decrease in electrical conductivity and PT concentration. Two phases of the hydrologic cycle were evidenced and determined by the depth and nutrient concentrations. The highest abundance of desmids occurred at the end of the rainy season when the nutrient availability and pH were higher, and the depth was reduced. Conclusions Our results suggest that the flood pulse was the determining factor of the local environmental conditions and that, together with the macrophyte morphological traits, it influenced desmid abundance and distribution in a floodplain lagoon in the semiarid region.

Extremely Low Lattice Thermal Conductivity and Significantly Enhanced Near-Room-Temperature Thermoelectric Performance in α-Cu2Se through the Incorporation of Porous Carbon.

In this work, a series of Cu2Se/x wt % porous carbon (PC) (x = 0, 0.2, 0.4, 0.6, 0.8, 1) composite materials were synthesized by ball milling and spark plasma sintering (SPS). The highly ordered porous carbon was synthesized by a hydrothermal method using mesoporous silica (SBA-15) as the template. X-ray diffraction results show that the incorporation of porous carbon induces a phase transition of Cu2Se from the β phase to the α phase. Meanwhile, the addition of porous carbon reduces the carrier concentration from 2.7 × 1021 to 2.45 × 1020 cm-3 by 1 order of magnitude. The decrease of the carrier concentration leads to the reduction of electrical conductivity and the increase of the Seebeck coefficient, which results in the enhancement of the power factor. On the other hand, the incorporation of porous carbon into Cu2Se increases the porosity of the composites and also introduces more interfaces between the two materials, which is evidenced by positron annihilation lifetime measurements. Both pores and interfaces greatly enhance phonon scattering, leading to extremely low lattice thermal conductivity. In addition, the decrease of electrical conductivity also causes a sufficient reduction in electronic thermal conductivity. Due to the above synergistic effects, the thermoelectric performance of the Cu2Se/PC composite is significantly enhanced with a maximum ZT value of 0.92 at 403 K in the Cu2Se/1 wt % PC composite, which is close to that of the Bi2Te3-based materials. Our work shows that α-Cu2Se has great potential for near-room-temperature thermoelectric materials.

Measurement of electrical conductivity of transformer oil based nanofluid

In this article, an attempt was made to evaluate the electrical conductivity of ananofluid based on transformer oil. For this purpose, several nanofluid samples with different concentrations of dielectric silicon dioxide nanoparticles and conductive zinc nanoparticles were prepared. The dielectric permittivity and electrical conductivity of the obtained nanofluids were measured experimentally. After processing the experimental results, a theoretical calculation was made using the Nielsen formula. After the calculation, the results were compared with the experimental data. In the process of comparative analysis, the correspondence of the calculated and experimental values of the dielectric permittivity was noted. There was also a discrepancy between the experimental and calculated values of electrical conductivity. An explanation is proposed for the discovered discrepancy between the calculated and experimental values. Presumably, the main reason for the decrease in electrical conductivity in the experiment is the adsorption of ion particles in the dielectric.

ALD-Based Interface Engineering for Improving Electrical Conductivity of Nanoporous Thermoelectric Materials

The way to improve the performance of thermoelectric materials is to break the strong correlation between electrical conductivity and thermal conductivity. Combining porous structures with atomic layer deposition (ALD) is a promising strategy to solve this problem. The porous structure introduced into thermoelectric materials effectively lowers the lattice thermal conductivity, greatly increasing performance. However, the formation of nanopores is accompanied by a decrease in electrical conductivity. Here, we create nanoporous Bi0.4Sb1.6Te3 powder formed through selective dissolution from the mixture of KCl and Bi0.4Sb1.6Te3 powder. We propose a strategy to control carrier concentration by ALD of ZnO on nanoporous Bi0.4Sb1.6Te3 powder, thereby improving electrical conductivity and lowering thermal conductivity. Even after spark plasma sintering, ZnO is conformally formed at the nanoporous Bi0.4Sb1.6Te3 grain boundaries. The electrical conductivity increases from 651.72 S/cm to 724.52 S/cm by interfacial reaction of ZnO and Bi0.4Sb1.6Te3. In addition, ZnO inhibits grain growth and creates numerous grain boundaries to lower the lattice thermal conductivity of the porous structure. As a result, the ZT of the nanoporous Bi0.4Sb1.6Te3 deposited with ZnO is increased by 46%. This study demonstrates that ALD is an effective method for improving the conductivity of nanoporous thermoelectric materials.

Створення та обробки мідних сплавів, легованих хромом, цирконієм та ванадієм

The rapid development of mechanical engineering and electrical engineering requires alloys that have high electrical conductivity and a high level of mechanical properties, including strength at elevated temperatures. Pure and low-alloyed copper are ductile, but low-strength materials, which prevents their application in many areas. The solution of such problem can be in alloying with metals that would increase strength characteristics while maintaining electrical conductivity as much as possible, including at high current and temperature loads. The main alloying elements analyzed in this work as effective strengthening components were Cr, Zr, and V. It is shown that the increase in strength while maintaining electrical conductivity depends to a greater extent on the chromium content, the concentration of which in alloys can reach 5-10 wt. %. It was established that to achieve optimal characteristics of strength and electrical conductivity, the concentration of chromium can be close to 0,1 wt. %, and zirconium - up to 0,2 wt. %. At the same time, both for alloys with a high chromium content and in low-alloyed compositions, the characteristics of strength and electrical conductivity can differ by only 10-20%. In the vast majority of cases, copper alloys with chromium and zirconium undergo a specific, sometimes compositional and multi-stage, deformation treatment, after which a fine crystalline structure with nano-sized allocations of strengthening dispersoid phases can be formed. All considered alloys show similar technological features of obtaining a high level of final properties - homogenization and tempering from temperatures of 900-1000 °С and aging at 500 °С for 2 hours or more. At the same time, the higher the content of chromium and zirconium, the more difficult the deformation and heat treatments will be. Additional microalloying with vanadium in the amount of up to 0.2 wt. % may increase strength without a noticeable decrease in electrical conductivity and without the need for the complication of deformation and heat treatments. Keywords: alloying of copper alloys, Cu-Cr-Zr, Cu-Cr-Zr-V, heat treatment, deformation, electrical conductivity.

Tuning the electrical, thermal, and mechanical properties of porous SiC ceramics using metal carbides

The effect of addition of various metal carbides on the electrical, thermal, and mechanical properties of porous SiC ceramics was investigated. The results showed a decrease in the electrical resistivity from 1.2 × 102 to 1.3 × 10-3 Ω‧cm and thermal conductivity from 14.2 to 3.6W.m-1K-1 whereas the compressive strength increased from 12.7 to 21.1–81.1MPa at ~60.2% porosity. The decrease in electrical resistivity and thermal conductivity was caused by the introduction of conductive carbides and multiple heterophase interfaces, respectively, in the porous ceramics. The electrical and thermal conductivities and compressive strength of porous SiC-based ceramics, processed with a SiC-B4C-VC-ZrC-NbC composition, were 8.0 × 102 Ω-1‧cm-1, 3.6W‧m-1K-1, and 58.0MPa, respectively. Therefore, it is proven that the electrical, thermal, and mechanical properties of porous SiC ceramics can be tuned over a wide range by adding a suitable combination of metal carbides.

EFFECT OF LOW-VELOCITY IMPACT DAMAGE ON THE ELECTROMAGNETIC INTERFERENCE SHIELDING EFFECTIVENESS OF CFRP COMPOSITES

Carbon fiber reinforced polymer (CFRP) composites are widely used engineering materials in aerospace technologies. These electrically conductive carbon-based materials, due to the lightness advantages, are preferred as shields against electromagnetic radiation, especially in aircraft and satellites. However, the performance losses caused by damage because of flying object collision such as bird, hail, or projectile contain significant uncertainty. Herein, the CFRP composite material was structurally damaged by low velocity impact test set-up at various energy levels between 2.5 to 10 joules, and then its electromagnetic interference (EMI) shielding performance was investigated. In addition, the electrical properties of the material were also examined, and the occurred damage status was evaluated by microscopy studies. Intrinsically, the increase in impact energy increases the grade of damage on body of the material. This results in a drastic decrease in electrical conductivity and EMI performance. In experiments, where 5 joule energy is detected as a threshold level, it has been observed that irreparable damage occurs at energy levels above this value.

A Comprehensive Investigation of BN and VC Reinforcements on the Properties of FSP AA6061 Composites

This present study investigated the impact of incorporating boron nitride (BN) and vanadium carbide (VC) reinforcements on various properties of friction stir processed (FSP) AA6061 alloy composites, focusing specifically on grain structure, thermal conductivity, electrical conductivity, and compressive strength. The findings indicate that VC more effectively refines the grain structure of the AA6061 alloy during FSP compared to BN. The inclusion of BN particles in the metal matrix composites resulted in a decrease in both thermal and electrical conductivity. In contrast, the addition of VC particles led to an increase in both thermal and electrical conductivity. The AA6061/VC composite material exhibited the highest thermal conductivity among all composites tested. The electrical conductivity of the hybrid-composite AA6061/30%BN+70%VC showed a slight reduction, measuring only 2.8% lower than the base alloy AA6061. The mono-composite AA6061/VC exhibited a marginal decrease in thermal conductivity, with a measured value only 7.5% lower than the conventional alloy AA6061. However, the mono-composite AA6061/BN displayed a more significant decline, exhibiting a loss of 14.7% and 13.9% in electrical and thermal conductivity, respectively. The composite material comprising 30% BN and 70% VC reinforcement demonstrated the highest compressive strength compared to all other tested composites. The observed percentage enhancement in the mechanical properties of mono and hybrid composites, compared to the parent AA6061 alloy, ranged from 17.1% to 31.5%.

Porous Ag2Se Fabricated by a Modified Cold Sintering Process with the Average zT Around Unity Near Room Temperature

AbstractSilver selenide (Ag2Se) is a promising material for thermoelectric applications near room temperature. This work proposes a new fabrication route for bulk Ag2Se via a modified cold sintering process (mCSP) to enhance its figure‐of‐merit (zT). Unlike conventional CSP, mCSP employs thiol‐amine (TA) as a liquid medium that completely undissolves Ag2Se, leading to a free flow of the TA solution within interparticle channels. By sintering at temperatures above the boiling point of TA, the liquid evaporates, leaving behind a bulk Ag2Se material with a tube‐like porous structure (open pores). These induced defects strongly influence thermoelectric properties of Ag2Se, with a substantial increase in the Seebeck coefficient and decrease in electrical conductivity. The overall power factor of the mCSP sample with TA surpasses that of the control sample without TA, consistent with effective band modeling of Ag2Se. Moreover, the created micropores during mCSP effectively suppresses the thermal conductivity, leading to a maximum zT above 1.0 at 400 K by optimizing mCSP parameters. Importantly, the average zT within the 300–400 K range is around unity, representing one of the highest reported values. Further optimization of mCSP parameters can enhance average zT beyond unity, making Ag2Se more competitive with state‐of‐the‐art materials near room temperature.

Reduction in phytotoxicity of a textile wastewater against Vigna radiata using Citrobacter sp. M41 in a bioaugmented packed bed column bioreactor

The current research was carried out to devise a biological strategy to remediate dyes and metal ions from textile wastewater. For this purpose, Citrobacter sp. M41 was isolated from a textile wastewater sample. This strain efficiently decolorized > 90 % of the added reactive black-5 (RB5) dye using yeast extract as a C source at 8.5 pH and 30 °C in mineral salt medium containing a mixture of metals (Pb2+, Ni2+ and Cd2+). Moreover, M41 showed > 90 % decolorization of RB5 beside > 80 % concurrent removal of hexavalent Chromium [Cr(VI)]. Furthermore, the granulated corncob and its biochar bioaugmented with M41 and filled within packed bed column based bioreactors efficiently (>90 %) removed the RB5 and Cr(VI) from a textile wastewater. The M41 bioaugmented corncob biochar resulted into a 60.8 %, 57.8 % and 68.7 % decrease in chemical oxygen demand (COD), electrical conductivity (EC) and total dissolved solids (TDS) of the wastewater, respectively. A phytotoxicity study conducted by using mung bean (Vigna radiata) as a test crop indicated that the treated synthetic wastewater was relatively less toxic as compared with the untreated wastewater. Therefore, it can be concluded that Citrobater sp. M41 is an important bio-resource for treatment of textile effluent polluted with azo dyes and Cr(VI).

Influence of Si content on thermoelectric properties of Mg2(Sn,Si) films by sputtering

Mg2(Sn,Si) films with different Si content were prepared by magnetron sputtering. The phase composition, surface and cross-sectional morphology, chemical composition and element distribution, carrier concentration, carrier mobility, electrical conductivity, Seebeck coefficient and power factor of the deposited Mg–Sn–Si films were studied. The results show that the deposited films are composed of Mg2(Sn,Si) solid solution phase and a small amount of metal Mg phase. The room temperature carrier concentration decreases and mobility increases with increasing Si content in deposited Mg–Sn–Si films, respectively. The room temperature electrical conductivity and Seebeck coefficient decreases and increases with increasing Si content, respectively. The deposited Mg2(Sn,Si) films with moderate Si content possess the maximum power factor value of 2.76 mW m−1 K−2 at 303 °C and its room temperature figure of merit reaches the highest value of 0.44. The thermal conductivity decreases with increasing Si content, indicating that the lattice distortion caused by Si doping can reduce the thermal conductivity of the deposited films.

ELECTROCONDUCTIVITY OF MOLTEN FLiNaK AND FLiNaK–CeF<sub>3</sub>

The eutectic mixture LiF–NaF–KF (FLiNaK) is promising as a carrier salt for molten-salt reactors. Cerium fluoride CeF3 can be considered as a simulant of plutonium fluoride PuF3. In this work, the temperature dependence of the electrical conductivity of the molten ternary eutectic LiF–KF–NaF containing from 0 to 25 mol % cerium fluoride in the temperature range 480–777°C. FliNaK–CeF3 mixtures containing up to 25 mol. % of cerium fluoride were prepared directly in the experimental cell, dropping the required amount of CeF3 into the melt and keeping mixtures of a given composition for 12 h at temperatures exceeding the liquidus temperatures of the studied compositions. The electrolyte resistance was determined from impedance hodographs, which were taken using the Z-1500J impedance meter. A two-electrode cell with Pt electrodes was used. Analysis of the experimental values of the electrical conductivity of double and triple fluoride melts KF–LiF available in the literature; KF–NaF; LiF–NaF–KF shows that our data on the electrical conductivity of the LiF–NaF–KF (FLiNaK) eutectic mixture are consistent with the general trend in electrical conductivity with increasing KF concentration in the melt. A significant decrease in the specific electrical conductivity of the molten system and a slight increase in the activation energy of electrical conductivity with an increase in the concentration of cerium fluoride are shown. The temperature dependences of the electrical conductivity of the molten system were approximated by second-order polynomials. The formation of the \({\text{CeF}}_{6}^{{3 - }}\) complex ion in the melt was confirmed by spectral studies. The Raman spectra of molten FLiNaK and FliNaK–CeF3 mixtures containing 8 and 15 mol. % of cerium fluoride were recorded. With an increase in the concentration of CeF3 in the melt, the amount of \({\text{CeF}}_{6}^{{3 - }}\) complex ions increases, which leads to an increase in the intensity of the observed vibrational bands.

Removal of butyl acetate in an industrial ef uent through a physicochemical treatment

Butyl acetate is an organic compound widely used in industry, focu- sing on industrial paint waste ef uents. Exposure to this pollutant at an average of 925 ppm can cause dizziness, drowsiness, respiratory tract irritation, and central nervous system suppression. That is why it seeks to minimize the risk associated with this contaminant through treatment alternatives. The characterization of the sample yielded the detection of the following contaminants: methyl ester, 1-butanol, 1-4 dioxane, butyl ester, 1-chlorobutane. The objective of this work was the design and development of combined treatments for the removal of butyl acetate in industrial waste ef uents. For this, a physicoche- mical treatment coupled to an advanced oxidation process (PAO) was implemented. The results showed that the coupled treatments are ef - cient for the removal of butyl acetate, methyl ester, 1-chlorobutane and 1-butanol, while for 1-4 dioxane it was reduced by approximate- ly 83%. The study was complemented with the evaluation of the fo- llowing parameters, resulting in a decrease in electrical conductivity of 99.5%, total suspended solids of 74%, color of 93%, turbidity of 55% and COD of 73%.

SPECTRAL-LUMINESCENT AND ELECTROPHYSICAL STUDY OF RADIATION OXIDATION OF BERYLLIUM IN WATER

The radiation oxidation of Be in water at room temperature in the absorbed dose range Dγ = 0.5…180 kGy was studied by radiothermoluminescence (RTL), infrared reflection-adsorption spectroscopy (IRRAS), and electrical conductivity. The participation and role of surface relaxing intermediate-active particles in the dynamics of changes in the oxidation process are considered. Using the RTL method, the role of surface oxygen hole centers generated by γ-irradiation and chemisorbed oxygen in the formation of nanooxide films was experimentally established. The formation of nanooxide films on the surface of Be in water was traced in the IR reflection spectra. The kinetics of radiation oxidation of beryllium has been studied and its radiation passivation has been established. According to the logarithmic dose dependence of the surface resistivity Be, two stages of the oxidation process were revealed. It is shown that the formation of nano oxide films leads to a decrease in the surface electrical conductivity of beryllium by 2 orders of magnitude and an increase in the thickness of oxide films by 1.6 times.

Investigating the size-dependent structural, optical, dielectric, and photocatalytic properties of benign-synthesized ZnO nanoparticles

Zinc oxide (ZnO) plays a vital role in numerous technological facets of semiconductors. Due to its captivating characteristics, it has garnered considerable interest in a diverse array of applications. In this study, the egg albumen-facilitated bio-template approach was utilized to fabricate ZnO nanoparticles, aiming to investigate the impact of varying albumen concentration ratios on the crystal structure, dimensions, and shape of the resulting ZnO nanoparticles. This approach provides more precise customization of the dimensions and configuration of the nanocrystals and is compatible with most documented physical techniques. Exploring the morphological impacts of unadulterated or altered zinc oxide nanocrystals on photocatalytic performance is crucial for maximizing solar energy absorption and utilization. However, this aspect has yet to receive much attention in previous studies. The photocatalytic rate was discovered to be independent of the ZnO particle size, but the geometry factor is of paramount significance. ZnO with a nanopencil shape exhibited a minimum of 1.81 times higher efficiency than spherical particles. Furthermore, the dielectric characteristics of ZnO nanoparticles (NPs) were investigated across a frequency range of 75 kHz to 7 MHz, considering the dependence on particle size. As the dimensions of the ZnO NPs diminish, there is a gradual rise in the dielectric permittivity, increasing from 20 to 82 with the escalation in frequency. In the context of ZnO nanoparticles (NPs), the Maxwell- Wagner polarization model can elucidate the phenomenon of robust interfacial polarization, particularly as the ZnO size diminishes. As the frequency increases, the AC conductivity exhibits a gradual augmentation. Likewise, in relation to the dielectric constant and losses, the electrical conductivity characteristics of all ZnO NPs samples exhibit a reliance on the size of the crystals, where a reduction in crystal size corresponds to a decrease in electrical conductivity. The utilization of eco-friendly nanomaterials is anticipated to pave the way for novel possibilities in their exceptional electronic applications as storage materials.

Assessing Soil Fertility Dynamics and Carbon Sequestration Potential in Groundnut (Arachis hypogaea L.) Cultivation Areas of Sri Satya Sai District, Andhra Pradesh, India

In 2021-2022, a study was conducted at the Agricultural Research Station in Anantapur, Andhra Pradesh, India, focusing on soil fertility changes and carbon storage potential in Sri Satya Sai district. A total of 300 soil samples were collected, 150 before and 150 after groundnut (Arachis hypogaea L.) cultivation in three blocks (i.e., Chennekothapalle, Ramagiri, and Roddam) of Sri Satya Sai District, Andhra Pradesh, India. Chennekothapalle exhibited a decline in pH from 6.83 to 6.53 after groundnut (Arachis hypogaea L.) cultivation, accompanied by a decrease in electrical conductivity (EC) levels from 0.22 to 0.18. Similarly, Ramagiri displayed a similar trend with a drop in pH from 7.03 to 6.63 and a decrease in EC from 0.22 to 0.20 dS/m. Roddam experienced a slight reduction in pH from 6.52 to 6.48 and a decrease in EC from 0.18 to 0.16 dS/m. Organic carbon (OC) content showed varying trends, with notable increases in Chennekothapalle (from 0.44% to 0.94%), Ramagiri (from 0.43% to 1.13%), and Roddam (from 0.3054% to 0.4454%) after cultivation. Nitrogen levels witnessed an increase in all three blocks, Chennekothapalle rising from 141.3 to 171.3 kgs/ha, Ramagiri from 162.11 to 192.11 kgs/ha, and Roddam from 129.44 to 154.44 kgs/ha. Additionally, Posphorus levels increased in Chennekothapalle (from 16.76 to 19.76 kgs/ha), Ramagiri (from 13.62 to 18.62 kgs/ha), and Roddam (from 30.24 to 35.24 kgs/ha) after cultivation. Similarly, Potassium levels showed increases in Chennekothapalle (from 159.07 to 184.07 kgs/ha), Ramagiri (from 161.04 to 195.04 kgs/ha), and Roddam (from 154.49 to 174.49 kgs/ha), indicating distinct patterns of soil fertility dynamics across these regions. In Chennekothapalle, the soil organic carbon content (TOC) increased from 0.004% to 0.009%, and there was a substantial rise in soil carbon stock (SCS) from 18.11 to 39.37 kgs/m². Carbon turnover, measured through mean CO2 levels, increased from 160.45 gms to 343.7 gms, and the Carbon Sequestration Potential (CSP) was 6900 Kgs. In Ramagiri, TOC saw an increase from 0.004% to 0.011%, with SCS improving from 30.92 to 37.38 kgs/m², indicating greater soil carbon storage. A significant rise in CO2 levels from 158.69 gms to 415.3 gms was observed, and CSP was 7700 Kgs. In Roddam, TOC increased from 0.003% to 0.004%, and SCS rose from 20.24 to 30.06 kgs/m², signaling improved soil carbon stocks. CO2 levels increased from 111.98 gms to 163.3 gms, reflecting enhanced carbon turnover, and remarkably, CSP was 3150 Kg. In comparing the three blocks, it's evident that Ramagiri exhibited the most substantial increase in soil fertility and carbon sequestration potential. While Chennekothapalle is showing significant improvements, Roddam experienced relatively modest changes in all parameters.

Humic acid plus manure increases the soil carbon pool by inhibiting salinity and alleviating the microbial resource limitation in saline soils

Fertilization strategies have been widely studied as an effective strategy to improve the structure and fertility of saline soils. However, the effect of the combination of different organic ameliorants on the soil carbon (C) pool is still not clear. We conducted a two-year field experiment to investigate the influences of organic ameliorants on soil organic C (SOC) and inorganic C (SIC) stocks, and enzymaticstoichiometry for both top and subsoil (i.e., 0–20 cm and 20–40 cm) in the semi-arid saline region of Western China. Compared to chemical fertilizer (CK) soils, the content and stock of total C and SOC at 0–40 cm soil layer under organic ameliorant (OM), humus acid plus OM (HA + OM), and biofertilizer plus OM (B + OM) were 9–40% higher, whilst the content and stock of SIC at 0–40 cm soil layer under HA + OM were 18% higher after two years. In addition, soil microorganisms were generally limited by phosphorus (P), and HA + OM reduced microbial P and nitrogen (N) limitations after two years application. Structural equation modeling showed that reduced microbial N and P limitation under HA + OM was mainly directly driven by the decrease in electrical conductivity (EC) content. Redundancy analysis and correlation analysis further confirmed that soil EC and microbial resource limitation were the main factors affecting soil C content. Furthermore, HA + OM promoted the positive regulation of SOC on SIC, which facilitated the formation of SIC content. The higher accumulation of SOC and SIC content under HA + OM were both beneficial to the enhancement of the total C stock in saline soil. Overall, our results provided an effective regime to improve the soil saline and microbial environments, and increase the potential for rapid enhancement of the C stock of saline soil in Northwest China.

Halophyte Elymus dahuricus colonization regulates microbial community succession by mediating saline-alkaline and biogenic organic matter in bauxite residue

Alkalinity regulation and nutrient accumulation are critical factors in the construction of plant and microbial communities and soil formation in bauxite residue, and are extremely important for sustainable vegetation restoration in bauxite residue disposal areas. However, the establishment and succession of microbial communities driven by plant colonization-mediated improvements in the physicochemical properties of bauxite residues remain poorly understood. Thus, in this study, we determined the saline-alkali properties and dissolved organic matter (DOM) components under plant growth conditions and explored the microbial community diversity and structure using Illumina high-throughput sequencing. The planting of Elymus dahuricus (E. dahuricus) in the bauxite residue resulted in a significant decrease in total alkalinity (TA), exchangeable Na, and electrical conductivity (EC) as well as the release of more tryptophan-like protein compounds and low-molecular-weight humic substances associated with biological activities into the bauxite residue substrate. Taxonomical analysis revealed an initial-stage bacterial and fungal community dominated by alkaline-tolerant Actinobacteriota, Firmicutes, and Ascomycota, and an increase in the relative abundances of the phyla Bacteroidota, Cyanobacteria, Chloroflexi, and Gemmatimonadota. The biological activities of phylum Actinobacteriota, Bacteroidota, and Gemmatimonadota were significantly associated with protein-like and UVA-like humic substances. As eutrophic bacteria, Proteobacteria participate in the transformation of humic substances and can not only utilize small molecules of organic matter and convert them into humic substances but also promote the gradual conversion of humic acids into simple molecular compounds. Our results suggest that plant roots secrete organic matter and microbial metabolites as the main biogenic organic matter that participates in the establishment and succession of the microbial community in bauxite residues. Root length affects bacterial and fungal diversity by mediating the production of protein-like substances.

Delving into the properties of nanostructured Mg ferrite and PEG composites: A comparative study on structure, electrical conductivity, and dielectric relaxation

Magnesium ferrite (MgFe2O4) and polyethylene glycol (PEG) are materials known for their versatility in various applications. This study presents a comprehensive comparative analysis of the electrical conductivity and dielectric relaxation of nanostructured MgFe2O4 and its composites with PEG. Through experimentation, it was observed that incorporating PEG into MgFe2O4 did not lead to a high relative observed decrease or increase in electrical conductivity at room temperature. The study revealed that the composites maintained stable electrical behavior at room temperature, with a dielectric constant value of around 9 and a loss tangent value of around 0.1 at high frequency (around 7 MHz). The electron-hole hopping mechanism was identified as the underlying cause for the strong dielectric dispersion with frequency. The low dielectric loss and conductivity of the MgFe2O4 and PEG/ferrite composites make them promising candidates for high-frequency switching applications and microelectronic devices, particularly in scenarios where negligible eddy currents are essential. Additionally, complex impedance data analysis demonstrated that the capacitive and resistive properties of the composites are primarily attributed to grain boundary processes. This study provides a comprehensive analysis of the electrical and dielectric properties of MgFe2O4 and PEG composites and highlights their potential for many applications in materials science, particularly in electrical and electronic devices.