Characterization of Amaranthus species: ability in nanoparticles fabrication and the antimicrobial activity against human pathogenic bacteria.

The present work aimed at differentiating five Amaranthus species from Saudi Arabia according to their morphology and the ability in nanoparticle formulation. Biogenic silver nanoparticles (AgNPs) were synthesized from leaf extracts of the five Amaranthus species and characterized by different techniques. Fourier-transform infrared spectroscopy (FT-IR) was used to identify the phyto-constituents of Amaranthus species. The nanoparticles (NPs) were characterized by UV-visible spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The antibacterial activity of the synthesized NPs was tested against Staphylococcus aureus, E. coli, Klebsiella pneumoniae and Pseudomonas aeruginosa using the agar well diffusion method. Spherical NPs varying in size and functional groups from the five plant species were demonstrated by TEM, DLS and FTIR analysis, respectively. Variations in NPs characteristics could be related to the phytochemical composition of each Amaranthus species since they play a significant role in the reduction process. EDX confirmed the presence of Ag in plant fabricated AgNPs. Antibacterial activity varied among the species, possibly related to the NPs characteristics. Varied characteristics for the obtained AgNPs may reflect variations in the phytochemical composition type and concentration among Amaranthus species used for their fabrication.

Sulfonation of Natural Carbonaceous Bentonite as a Low-Cost Acidic Catalyst for Effective Transesterification of Used Sunflower Oil into Diesel; Statistical Modeling and Kinetic Properties.

Bentonite sample enriched in organic matters (oil shale) was functionalized with -SO3H sulfonated carbonaceous bentonite (S-CB) by sulfonation process as a low-cost and effective acidic catalyst for the transesterification spent sunflower oil (SFO). The sulfonation effect was followed by several analytic techniques including X-ray diffraction, Fourier transform infrared, and scanning electron microscopy analysis. The catalytic performance of the sulfonated product was evaluated based on a statistical design which was built according to the response surface methodology and the central composite rotatable design. Using the S-CB acidic catalyst in the transesterification of spent SFO resulted in an actual biodiesel yield of 96% at studied conditions of 85 min at reaction interval, 50 °C as temperature,15:1 as methanol/oil ratio, and 3.5 wt % as S-CB loading. Moreover, the optimization function suggested enhancement to obtained yield up to 97.9% by selecting the values of temperature at 62 °C, the time at 98.5 min, the methanol/SFO ratio at 14.4:1, and S-CB loading at 3.4 wt %. The technical evaluation of the SFO biodiesel reflected the suitability of the product to be used as biofuels according to international standards. The kinetic behavior of the SFO transesterification reaction over S-CB is of pseudo-first order properties and of low activation energy. Finally, the synthetic S-CB as a solid acidic catalyst is of significant reusability and was reused five times with remarkable biodiesel yields.

Global Invasion Risk Assessment of Prosopis juliflora at Biome Level: Does Soil Matter?

Prosopis juliflora is one of the most problematic invasive trees in tropical and subtropical regions. Understanding driving forces affecting the potential global distribution would help in managing its current and future spread. The role of climate on the global spatial distribution of P. juliflora has been well studied, but little is known about the role of soil and human impacts as potential drivers. Here, we used maximum entropy (MaxEnt) for species distribution modelling to understand the role of climate (C), soil (S) and human impacts (H), C+S, and C+S+H in controlling the potential invasion range of P. juliflora, and to project its global potential invasive risk. We defined the top threatened global biomes, as predicted by the best-selected model. The incorporation of the edaphic factors improved the model performance and enhanced the accuracy of the outcome. Our findings revealed that the potential invasion risk increases with increases in mean temperature of the driest quarter (Bio9), soil alkalinity and clay fractions. Arid and semi-arid lands are at the highest risk of invasion than other moist biomes.

Endemic Juniperus Montane Species Facing Extinction Risk under Climate Change in Southwest China: Integrative Approach for Conservation Assessment and Prioritization.

Climate change is an important driver of biodiversity loss and extinction of endemic montane species. In China, three endemic Juniperus spp. (Juniperus pingii var. pingii, J. tibetica, and J. komarovii) are threatened and subjected to the risk of extinction. This study aimed to predict the potential distribution of these three Juniperus species under climate change and dispersal scenarios, to identify critical drivers explaining their potential distributions, to assess the extinction risk by estimating the loss percentage in their area of occupancy (AOO), and to identify priority areas for their conservation in China. We used ensemble modeling to evaluate the impact of climate change and project AOO. Our results revealed that the projected AOOs followed a similar trend in the three Juniperus species, which predicted an entire loss of their suitable habitats under both climate and dispersal scenarios. Temperature annual range and isothermality were the most critical key variables explaining the potential distribution of these three Juniperus species; they contribute by 16-56.1% and 20.4-38.3%, respectively. Accounting for the use of different thresholds provides a balanced approach for species distribution models' applications in conservation assessment when the goal is to assess potential climatic suitability in new geographical areas. Therefore, south Sichuan and north Yunnan could be considered important priority conservation areas for in situ conservation and search for unknown populations of these three Juniperus species.