Evaluating the roughness dynamics of kefir biofilms grown on Amazon cupuaçu juice: a monofractal and multifractal approach

Cupuaçu (Theobroma grandiflorum): A Multifunctional Amazonian Fruit with Extensive Benefits

The Amazon region is known for its continental dimension, water abundance, and especially for the rich biodiversity that this biome hosts. Among the thousands of plant species in the Amazon, many represent food sources. Among these, cupuaçu (Theobroma grandiflorum (Willd. ex Spreng.) K.Schum.) stands out as an iconic fruit with an exotic flavor, appreciated for its remarkable organoleptic properties. The present review aims to provide a comprehensive description of its biology, agronomical uses, nutritional values, chemical compositions, medicinal properties, and industrial applications. The search based on scientific articles demonstrates T. grandiflorum as a valuable ingredient for the food, cosmetic and pharmaceutical sectors. Data analysis demonstrates that cupuaçu cultivation and processing contribute to the strengthening of local production chains and promotes the development of small communities, and thus the bioeconomy in the Amazon region. In this sense, since the last decade, cultivar improvement has required multidisciplinary efforts, resulting in disease-resistant plants with better productivity. Regarding its chemical composition, T. grandiflorum is a notable source of methylxanthine alkaloids, polyphenols, aroma compounds, and lipids. The presence of these compounds supports the use of cupuaçu in various products and help us to understand the potential health benefits of its consumption. Through the integration of all collected information, key gaps in basic and applied sciences were observed, highlighting the need for more research to uncover novel applications and products of T. grandiflorum. The development of new products based on biodiversity is fundamental to promoting environmental and economic sustainability, which are key steps to the survival of the Amazon rainforest. Therefore, this work summarizes the knowledge on this source and sheds light on a food source that is little known outside of the Amazon borders.

The fractal geometry of polymeric materials surfaces: surface area and fractal length scales

Using three common polymeric materials (polypropylene (PP), polytetrafluoroethylene (PTFE) and polycaprolactone (PCL)), a standard oxygen-plasma treatment and atomic force microscopy (AFM), we performed a scaling analysis of the modified surfaces yielding effective Hurst exponents (H ≃ 0.77 ± 0.02 (PP), ≃0.75 ± 0.02 (PTFE), and ≃0.83 ± 0.02 (PCL)), for the one-dimensional profiles, corresponding to the transversal sections of the surface, by averaging over all possible profiles. The surface fractal dimensions are given by ds = 3 - H, corresponding to ds ≃ 2.23, 2.25, and 2.17, respectively. We present a simple method to obtain the surface area from the AFM images stored in a matrix of 512 × 512 pixels. We show that the considerable increase found in the surface areas of the treated samples w.r.t. to the non-treated ones (43% for PP, 85% for PTFE, and 25% for PCL, with errors of about 2.5% on samples of 2 µm × 2 µm) is consistent with the observed increase in the length scales of the fractal regime to determine H, typically by a factor of about 2, extending from a few to hundreds of nanometres. We stipulate that the intrinsic roughness already present in the original non-treated material surfaces may serve as 'fractal' seeds undergoing significant height fluctuations during plasma treatment, suggesting a pathway for the future development of advanced material interfaces with large surface areas at the nanoscale.

Nanoscale morphology, optical dynamics and gas sensor of porous silicon

We investigated the multifaceted gas sensing properties of porous silicon thin films electrodeposited onto (100) oriented P-type silicon wafers substrates. Our investigation delves into morphological, optical properties, and sensing capabilities, aiming to optimize their use as efficient gas sensors. Morphological analysis revealed the development of unique surfaces with distinct characteristics compared to untreated sample, yielding substantially rougher yet flat surfaces, corroborated by Minkowski Functionals analysis. Fractal mathematics exploration emphasized that despite increased roughness, HF/ethanol-treated surfaces exhibit flatter attributes compared to untreated Si sample. Optical approaches established a correlation between increased porosity and elevated localized states and defects, influencing the Urbach energy value. This contributed to a reduction in steepness values, attributed to heightened dislocations and structural disturbances, while the transconductance parameter decreases. Simultaneously, porosity enhances the strength of electron‒phonon interaction. The porous silicon thin films were further tested as effective gas sensors for CO2 and O2 vapors at room temperature, displaying notable changes in electrical resistance with varying concentrations. These findings bring a comprehensive exploration of some important characteristics of porous silicon surfaces and established their potential for advanced industrial applications.

New Physico-Chemical Analysis of Magnesium-Doped Hydroxyapatite in Dextran Matrix Nanocomposites

The new magnesium-doped hydroxyapatite in dextran matrix (10MgHApD) nanocomposites were synthesized using coprecipitation technique. A spherical morphology was observed by scanning electron microscopy (SEM). The X-ray diffraction (XRD) characterization results show hydroxyapatite hexagonal phase formation. The element map scanning during the EDS analysis revealed homogenous distribution of constituent elements of calcium, phosphor, oxygen and magnesium. The presence of dextran in the sample was revealed by Fourier transform infrared (FTIR) spectroscopy. The antimicrobial activity of the 10MgHAPD nanocomposites was assessed by in vitro assays using Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Streptococcus mutans ATCC 25175, Porphyromonas gingivalis ATCC 33277 and Candida albicans ATCC 10231 microbial strains. The results of the antimicrobial assays highlighted that the 10MgHApD nanocomposites presented excellent antimicrobial activity against all the tested microorganisms and for all the tested time intervals. Furthermore, the biocompatibility assays determined that the 10MgHApD nanocomposites did not exhibit any toxicity towards Human gingival fibroblast (HGF-1) cells.