Effect of Land Use Change on Molecular Composition and Concentration of Organic Matter in an Oxisol.

Land use change from native vegetation to cropping can significantly affect the quantity and quality of soil organic matter (SOM). However, it remains unclear how the chemical composition of SOM is affected by such changes. This study employed a sequential chemical extraction to partition SOM from an Oxisol into several distinct fractions: water-soluble fractions (ultrapure water (W)), organometal complexes (sodium pyrophosphate (PP)), short-range ordered (SRO) oxides (hydroxylamine-HCl (HH)), and well-crystalline oxides (dithionite-HCl (DH)). Coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), the impact of land use change on the molecular composition of different OM fractions was investigated. Greater amounts of OM were observed in the PP and HH fractions compared to other fractions, highlighting their importance in SOM stabilization. The composition of different OM fractions varied based on extracted phases, with lignin-like and tannin-like compounds being prevalent in the PP and HH fractions, while aliphatic-like compounds dominated in the DH fraction. Despite changes in the concentration of each OM fraction from native vegetation to cropping, there was little influence of land use change on the molecular composition of OM associated with different mineral phases. No significant selective loss or preservation of organic carbon compounds was observed, indicating the composition of SOM remained unchanged.

Synthesis of bio-stabilized silver nanoparticles using Roccella montagnei, their anticandidal capacities & potential to inhibit the virulence factors in fluconazole-resistant Candida albicans.

Candida species is the causative agent in approximately 80% of invasive mycoses and drug-resistant Candida albicans is among the four strains of 'critical priority group' framed by WHO. Lichens are endowed with some rare phytochemicals and a plethora of therapeutics viz. antifungal capacities of Roccella montagnei. Biosynthesis of silver nanoparticles (AgNPs) using lichen could offer an eco-friendly, and cost-effective alternative against emerging 'microbial resistance.' Therefore, the objective was to biosynthesize silver nanoparticles (Rm-AgNPs) using a Hydro-alcoholic (1:1) extract of R. montagnei to develop a potent anticandidal agent against Fluconazole-resistant C. albicans NBC099. UV-Spectroscopy identified AgNPs specific-peak of Rm-AgNPs at 420-440 nm and FTIR revealed the presence of amines, alcohol, aromatic compounds, and acids. SEM and TEM analysis indicated that Rm-AgNPs are spherical shaped with a size range of 10-50 nm. Zetasizer analysis indicated that particles are highly stable and have a mean hydrodynamic diameter of 116 nm with a zeta potential charge of - 41 mV. XRD analysis suggested face centered cubic crystal lattice structure. Results indicated that Rm-AgNPs strongly inhibited the growth of NBC099 at a minimum inhibitory concentration (IC50) of ≤ 15 µg. C. albicans culture treated with Rm-AgNPs at concentrations below IC50, down-regulates the production of different virulence factors in NBC099, viz. hyphal formation (> 85%), biofilms production (> 80%), phospholipase, esterase, proteinase activity. The apoptosis assay demonstrated the Rm-AgNPs induced apoptosis in NBC099 cells via oxidative stress. Interestingly, Rm-AgNPs showed negligible cytotoxicity (< 6%) in murine RAW 246.7 macrophage cells at a concentration above 15 µg/mL. Therefore, Rm-AgNPs have been offered as an anti-candida alternative that can be utilized to improve the efficacy of already available medications.

Quantitative phase contrast X-ray tomography of aluminium metal matrix composite.

The quantitative assessment of micro-structure and load-induced damages in Al-SiC metal matrix composites (MMC) is important for its design optimization, performance evaluation and structure-property correlation. X-ray Phase contrast micro-tomography is potentially used for evaluation of its 3 dimensional micro-structure manifested in the form of voids, cracks, embedded particles, and load-induced damages. However, the contrast between Al matrix and SiC particles is insufficient for their clear morphological identification and quantitative assessment. In the present study, we have proposed and applied single image-based phase retrieval as a pre-processing step to micro-tomography reconstruction for improved assessment of micro-structure and cohesion-induced damages in Al-SiC MMC. The advantages of applying different phase retrieval techniques in the enhancement of image quality and morphological quantification of SiC particles, pores and cohesion damages are discussed. It is observed that the Paganin method offers the best improvement in contrast to noise ratio for the measurement of SiC particles embedded in the Al matrix.

Demostracion de un efecto espiroqueticida de los productos quimicos anticonceptivos sobre Treponema pallidum. / Demonstration of spirocheticial effect of chemical contraceptives on Treponema pallidum

Se ensayaron cinco productos anticonceptivos para uso intravaginal y una preparacion germicida vaginal para determinar su efecto en Treponema pallidum. Los resultados hacen pensar que posiblemente esos productos podrian ser de utilidad para prevenir la transmision de la sifilis de persona a persona