Characterization of rhizospheric fungi and their in vitro antagonistic potential against myco-phytopathogens invading Macrotyloma uniflorum plants.

Microorganisms have become more resistant to pesticides, which increases their ability to invade and infect crops resulting in decreased crop productivity. The rhizosphere plays a crucial role in protecting plants from harmful invaders. The purpose of the study was to investigate the antagonistic efficiency of indigenous rhizospheric fungal isolates against phytopathogens of M. uniflorum plants so that they could be further used as potent Biocontrol agents. Thirty rhizospheric fungal isolates were collected from the roots of the Macrotyloma uniflorum plant and initially described morphologically for the present study. Further, in vitro tests were conducted to evaluate the antifungal activity of these strains against four myco-phytopathogens namely Macrophamina phaseolina, Phomopsis sp. PhSFX-1, Nigrospora oryzae, and Boeremia exigua. These pathogens are known to infect the same crop plant, M. uniflorum, and cause declines in crop productivity. Fifteen fungal strains out of the thirty fungal isolates showed some partial antagonistic activity against the myco-phytopathogens. The potent fungal isolates were further identified using molecular techniques, specifically based on the internal transcribed spacer (ITS) region sequencing. Penicillium mallochii, Cladosporium pseudocladosporioides, Aspergillus chevalieri, Epicoccum nigrum, Metarhizium anisopliae, and Mucor irregularis were among the strains that were identified. These potent fungal strains showed effective antagonistic activity against harmful phytopathogens. Current findings suggest that these strains may be taken into consideration as synthetic fungicides which are frequently employed to manage plant diseases alternatives.

In-vitro and preclinical testing of bacillus subtilis UBBS-14 probiotic in rats shows no toxicity.

Introduction: Probiotics made from Bacillus subtilis provide a wide spread of health benefits, particularly in the treatment of diarrhea and gastrointestinal problems. Herein, we employed in vitro and in vivo paradigms to assess the potential adverse effects and toxicity of B. subtilis UBBS-14. Materials and methods: According to Organization for Economic Co-operation and Development (OECD) 423 and 407 requirements, a preclinical investigation was conducted in male and female Sprague-Dawley rats. Acute toxicity was examined following a single peroral (PO) administration of 5,000 mg/kg body weight (bw) i.e. equivalent to 500 billion colony-forming units (CFU) per kg bw. Single administration of B. subtilis UBBS-14 showed no mortality or adverse effects until the 14-day observation period, indicating LD50 is >5,000 mg/kg bw. Results: Incubation of B. subtilis UBBS-14 with Caco2, HT29, and Raw 264.7 cell lines, showed no cytotoxic effects. This probiotic strain was also found responsive to the majority of antibiotics. For a 28-day repeated dose toxicity study, rats were administered 100, 500, and 1,000 mg/kg bw daily once (10, 50, and 100 billion CFU/kg bw/day, respectively) doses of B. subtilis UBBS-14. No notable changes were seen in the morphology, weight, and histopathology of the critical internal organs. The haematological, biochemical, electrolyte (sodium, potassium, chloride, and calcium), and urine analytical results were within the normal range and equivalent to the vehicle-treated group. Conclusion: B. subtilis UBBS-14's no-observed-effect level (NOEL) was thus determined to be >1,000 mg/kg bw/day following a 28-day oral dosing.

Anomalous Correlation between Thermal Conductivity and Elastic Modulus in Two-Dimensional Hybrid Metal Halide Perovskites.

Device-level implementation of soft materials for energy conversion and thermal management demands a comprehensive understanding of their thermal conductivity and elastic modulus to mitigate thermo-mechanical challenges and ensure long-term stability. Thermal conductivity and elastic modulus are usually positively correlated in soft materials, such as amorphous macromolecules, which poses a challenge to discover materials that are either soft and thermally conductive or hard and thermally insulative. Here, we show anomalous correlations of thermal conductivity and elastic modulus in two-dimensional (2D) hybrid organic-inorganic perovskites (HOIP) by engineering the molecular interactions between organic cations. By replacing conventional alkyl-alkyl and aryl-aryl type organic interactions with mixed alkyl-aryl interactions, we observe an enhancement in elastic modulus with a reduction in thermal conductivity. This anomalous dependence provides a route to engineer thermal conductivity and elastic modulus independently and a guideline to search for better thermal management materials. Further, introducing chirality into the organic cation induces a molecular packing that leads to the same thermal conductivity and elastic modulus regardless of the composition across all half-chiral 2D HOIPs. This finding provides substantial leeway for further investigations in chiral 2D HOIPs to tune optoelectronic properties without compromising thermal and mechanical stability.

Ferroelectric Domain Wall Engineering Enables Thermal Modulation in PMN-PT Single Crystals.

Acting like thermal resistances, ferroelectric domain walls can be manipulated to realize dynamic modulation of thermal conductivity (k), which is essential for developing novel phononic circuits. Despite the interest, little attention has been paid to achieving room-temperature thermal modulation in bulk materials due to challenges in obtaining a high thermal conductivity switching ratio (khigh /klow ), particularly in commercially viable materials. Here, room-temperature thermal modulation in 2.5 mm-thick Pb(Mg1/3 Nb2/3 )O3 -xPbTiO3 (PMN-xPT) single crystals is demonstrated. With the use of advanced poling conditions, assisted by the systematic study on composition and orientation dependence of PMN-xPT, a range of thermal conductivity switching ratios with a maximum of ≈1.27 is observed. Simultaneous measurements of piezoelectric coefficient (d33 ) to characterize the poling state, domain wall density using polarized light microscopy (PLM), and birefringence change using quantitative PLM reveal that compared to the unpoled state, the domain wall density at intermediate poling states (0< d33

Thickness-Dependent Thermal Conductivity and Phonon Mean Free Path Distribution in Single-Crystalline Barium Titanate.

Nanosized perovskite ferroelectrics are widely employed in several electromechanical, photonics, and thermoelectric applications. Scaling of ferroelectric materials entails a severe reduction in the lattice (phonon) thermal conductivity, particularly at sub-100 nm length scales. Such thermal conductivity reduction can be accurately predicted using the information of phonon mean free path (MFP) distribution. The current understanding of phonon MFP distribution in perovskite ferroelectrics is still inconclusive despite the critical thermal management implications. Here, high-quality single-crystalline barium titanate (BTO) thin films, a representative perovskite ferroelectric material, are grown at several thicknesses. Using experimental thermal conductivity measurements and first-principles based modeling (including four-phonon scattering), the phonon MFP distribution is determined in BTO. The simulation results agree with the measured thickness-dependent thermal conductivity. The results show that the phonons with sub-100 nm MFP dominate the thermal transport in BTO, and phonons with MFP exceeding 10 nm contribute ≈35% to the total thermal conductivity, in significant contrast to previously published experimental results. The experimentally validated phonon MFP distribution is consistent with the theoretical predictions of other complex crystals with strong anharmonicity. This work paves the way for thermal management in nanostructured and ferroelectric-domain-engineered systems for oxide perovskite-based functional materials.

Synergistic Effects of Boron Nitride (BN) Nanosheets and Silver (Ag) Nanoparticles on Thermal Conductivity and Electrical Properties of Epoxy Nanocomposites.

Polymer composites, with both high thermal conductivity and high electrical insulation strength, are desirable for power equipment and electronic devices, to sustain increasingly high power density and heat flux. However, conventional methods to synthesize polymer composites with high thermal conductivity often degrade their insulation strength, or cause a significant increase in dielectric properties. In this work, we demonstrate epoxy nanocomposites embedded with silver nanoparticles (AgNPs), and modified boron nitride nanosheets (BNNSs), which have high thermal conductivity, high insulation strength, low permittivity, and low dielectric loss. Compared with neat epoxy, the composite with 25 vol% of binary nanofillers has a significant enhancement (~10x) in thermal conductivity, which is twice of that filled with BNNSs only (~5x), owing to the continuous heat transfer path among BNNSs enabled by AgNPs. An increase in the breakdown voltage is observed, which is attributed to BNNSs-restricted formation of AgNPs conducting channels that result in a lengthening of the breakdown path. Moreover, the effects of nanofillers on dielectric properties, and thermal simulated current of nanocomposites, are discussed.