The impact of different confinement barrier (CB) compositions on the emission of InAs quantum dots (QDs) in dot-in—a-well (DWELL) structures embedded in GaAs/Al0.30Ga0.70As heterostructures has been investigated both before and after thermal annealing. Two DWELL structures were compared: (1) a structure consisting of an In0.15Ga0.85As buffer layer and an Al0.30Ga0.70As CB layer; (2) a structure incorporating an In0.25Ga0.75As buffer layer and Al0.40Ga0.45In0.15As CB layer. The QD structures were studied in their as-grown (AG) state (without annealing) and after annealing at 640 °C or 710 °C for 2 h in an Ar atmosphere. To investigate variations in the QDs and quantum well (QW) parameters, a combination of techniques was employed, including photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM), and high-resolution X-ray diffraction (HR-XRD). In addition, numerical simulations of the HR-XRD scans were performed, and PL measurements were conducted over a temperature range of 10–400 K. The advantages of structure 2 (Al0.40Ga0.45In0.15As CB), compared to structure 1 (Al0.30Ga0.70As CB), after high-temperature treatments were demonstrated and analyzed. The results provide valuable insights for improving InAs QD structures for telecommunication and optoelectronic applications.
This work presents a preliminary study using an opto-mechatronic system to measure the refractive index and thermo-optical behavior of blood plasma. The setup employs a 650 nm laser and a displacement sensor on a linear actuator to detect beam deviation through small fluid volumes. Using water-based fluids with different glucose levels, a linear decreasing trend in refractive index with temperature was observed. Furthermore, plasma samples with different glucose concentrations were evaluated across a temperature range. One sample, corresponding to a markedly elevated glucose level, exhibited a dual thermo-optical response that suggests a transition to a different optical regime influenced by complex biomolecular composition. To contextualize these findings, numerical modeling under high irradiance was incorporated as a conceptual framework to explore how thermo-optical properties may evolve under stronger light–matter interactions. The simulations indicate that both glucose concentration and molecular polarizability can modulate the thermo-optical coefficient under nonlinear conditions. Rather than demonstrating molecular specificity, these results serve as initial evidence that optical parameters are sensitive to plasma composition and may guide future studies aimed at establishing selective, light-based biochemical analysis.
Enterococcus cecorum is an emerging opportunistic pathogen in poultry and its increasing antimicrobial resistance highlights the need for alternative control strategies. In this study, monometallic silver (AgNPs), copper (CuNPs), and bimetallic silver-copper (AgCuNPs) nanoparticles were synthesized and evaluated for their antibacterial activity against a clinical E. cecorum isolate. Physicochemical characterization by UV-Vis spectroscopy, zeta potential, transmission electron microscopy (TEM), X-ray diffraction, and nanoparticle tracking analysis (NTA) confirmed the formation of NPs with distinct size, surface, and dispersion properties. TEM revealed mean particle sizes of 10.5 +/- 4.1 nm (AgNPs), 22.0 +/- 9.3 nm (CuNPs), and 6.7 +/- 3.4 nm (AgCuNPs), while all systems exhibited negative surface charge. Antimicrobial activity was concentration dependent, AgNPs exhibited strong efficacy, with a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 6 and 36 ppm, respectively, whereas CuNPs showed reduced bactericidal activity (MIC/MBC: 6/> 48 ppm). In contrast, AgCuNPs achieved a lower MIC (3 ppm) while maintaining a comparable MBC (48 ppm), indicating enhanced antibacterial potency on a mass-concentration basis. Moreover, NTA revealed that, despite requiring lower total metal mass, AgCuNPs delivered a greater nanoparticle flux at the MIC (3.8 & times; 10(9) NPs ml(-1)) than monometallic NPs (similar to 2.3 & times; 10(9) NPs ml(-1)), representing an approximately 1.7-fold increase in particle concentration. Similarly, the nanoparticle-to-bacteria ratio was also higher for AgCuNPs (37 800 NPs CFU-1) compared with monometallic NPs (23 000 NPs CFU-1), indicating increased nanoparticle availability per bacterial cell during antimicrobial exposure. This increased particle availability, together with reduced particle and crystallite size, likely enhanced nanoparticle-cell interactions and contributed to improved antibacterial activity. Taken together, these findings support AgCuNPs as promising alternative or complementary antimicrobial agents for controlling E. cecorum in poultry production systems and demonstrate the value of nanoparticle flux and the nanoparticle-to-bacteria ratio as complementary descriptors for interpreting nano-bio antimicrobial performance beyond mass-based concentration metrics.
Aflatoxin B1 (AFB1) contamination of feed used in poultry farming is an important issue in food safety since it compromises animal productivity and leads to the transfer of toxic waste to the food chain. In this sense, as an alternative to conventional mineral adsorbents, in the present study, two sustainable and low-cost biochars were obtained from agro-industrial waste of orange peel (B-OP) and guava leaves (B-GL) to evaluate their efficiency in the removal of AFB1 in an in vitro avian model. Biochars were obtained from pyrolysis and characterized in terms of particle size, surface area, morphology, surface charge, surface chemistry, and pore size. Furthermore, their adsorption capacity was evaluated in an avian in vitro model. The results showed that B-OP had a smaller particle size (55.30 µm), a larger specific surface area (31.50 m2/g), and a smaller pore size (2.38 nm) than B-GL (82.88 µm, 9.74 m2/g, and 6.24 nm). Furthermore, the biochars presented different morphologies, FTIR spectra, and zeta potentials. In the avian in vitro model, the feed matrix reduced the effectiveness of AFB1 removal compared to the in vitro model using only buffer solutions. However, B-OP (27.4%) significantly outperformed B-GL (22.7%) in the intestinal segment. The valorization of these agro-industrial wastes into biochar represents an economical and sustainable strategy for removing AFB1 and strengthening food security.
Aflatoxin B1 (AFB1) is one of the most toxic and prevalent mycotoxins in poultry feed, posing serious risks to animal health and food safety. In this study, fluorinated silica nanoparticles (F-SiO₂NPs) were synthesized via a modified Stöber sol–gel method and evaluated as adsorbents for AFB1 using a dynamic in vitro poultry gastrointestinal model. Comprehensive structural and surface characterization using multiple complementary techniques confirmed the formation of spherical, amorphous silica nanoparticles (SiO₂NPs) and the successful grafting of fluorinated moieties, which significantly increased surface hydrophobicity. Adsorption experiments were conducted at two nanoparticle dosages (0.1 and 1
