Search for: All records

This study presents the fabrication and characterization of highly selective, room-temperature gas sensors based on ternary zinc oxide–molybdenum disulfide–titanium dioxide (ZnO-MoS2-TiO2) nanoheterostructures. Integrating two-dimensional (2D) MoS2 with oxide nano materials synergistically combines their unique properties, significantly enhancing gas sensing performance. Comprehensive structural and chemical analyses, including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR), confirmed the successful synthesis and composition of the ternary nanoheterostructures. The sensors demonstrated excellent selectivity in detecting low concentrations of nitrogen dioxide (NO2) among target gases such as ammonia (NH3), methane (CH4), and carbon dioxide (CO2) at room temperature, achieving up to 58% sensitivity at 4 ppm and 6% at 0.1 ppm for NO2. The prototypes demonstrated outstanding selectivity and a short response time of approximately 0.51 min. The impact of light-assisted enhancement was examined under 1 mW/cm2 weak ultraviolet (UV), blue, yellow, and red light-emitting diode (LED) illuminations, with the blue LED proving to deliver the highest sensor responsiveness. These results position ternary ZnO-MoS2-TiO2 nanoheterostructures as highly sensitive and selective room-temperature NO2 gas sensors that are suitable for applications in environmental monitoring, public health, and industrial processes. 

One of the main attributes that highlight the final quality of a gourmet cup of coffee is its aroma. Aromas vary according to a variety of plant and environmental variables, among others. This study aimed to characterize volatile and semivolatile compounds according to the Coffee arabica "Limani" berries ripening stages (healthy and brocaded). The study used different extraction methodologies to capture the broad spectrum of volatile, semivolatile organic compounds in coffee berries and berry borer (CBB). The methodologies used in the study included: enfleurage, headspace SPME (solid-phase microextraction), absorbent trap, and direct immersion SPME. Our study generated a Profile for coffee berries and CBB w with 228 compounds. Esters, cyclic, and benzyl compounds represent 65.6% of the total. The first three types of compounds that most attract our sense of smell constitute 40.5% of the compounds found; 1.3% aldehydes, 2.6% alcohols, and 36.6% benzyl. Overripe berries have high volatile emissions and show a composition dominated mainly by esters followed by alcohols, ketones, and aldehydes. The lowest-level compounds were monoterpenes. The number of compounds found in CBB varied according to sex. In summary, the CBB damage harms coffee berries' quality and aroma. The complete profile compounds generated will help better understand insect-plant relationships and potentially develop effective bait traps. 

Society has long been exposed to naturally-occurring nanoparticles. Due to their ubiquitous nature, biological systems have adapted and built protection against their potential effects. However, for the past decades, there have been onslaughts of newly engineered nanoparticles being released in the environment with no known effects on ecosystems. Although these materials offer distinct advantages in manufacturing processes, such as odor-free fabric or controlled drug delivery, their fate in nature has yet to be thoroughly investigated. As the size of an already-large NPs market is expected to grow, due to advances in synthetic biology, it is vital that we increase our understanding of their impacts on human, food and natural ecosystems. Recent studies have shown that NPs affect phytoplankton biomass and diversity in the ocean, solely by regulating micronutrients bioavailability. These types of changes could ultimately impact several biogeochemical cycles, as phytoplankton are responsible for almost half of the primary production on earth. Consequently, this study was designed to evaluate the impact of various concentrations (0µM, 20µM, 40µM, 80µM and 100µM) of several manufactured nanoparticles (gold, carbon and iron) on the dynamics of four economically important microalgae strains. Responses, such as chlorophyll content, protein, lipid content, lipid profile, biomass and cell morphology were monitored over a period of two weeks. No significant acute toxicity was exhibited within the first 24 hours of exposure. However, after 4 days, a remarkably high mortality rate was detected with increasing NPs concentrations of Fe60, C80 and Au60. Iron suspensions were found to be more toxic to the microalgae strains tested than those of Gold and Carbon under comparable regimes. Further investigations with other, either positively or negatively charged nanoparticles, should provide a deeper understanding on the impacts on these engineered materials in our ecosystems. 

Society has long been exposed to naturally-occurring nanoparticles. Due to their ubiquitous nature, biological systems have adapted and built protection against their potential effects. However, for the past decades, there have been onslaughts of newly engineered nanoparticles being released in the environment with no known effects on ecosystems. Although these materials offer distinct advantages in manufacturing processes, such as odor-free fabric or controlled drug delivery, their fate in nature has yet to be thoroughly investigated. As the size of an already-large NPs market is expected to grow, due to advances in synthetic biology, it is vital that we increase our understanding of their impacts on human, food and natural ecosystems. Recent studies have shown that NPs affect phytoplankton biomass and diversity in the ocean, solely by regulating micronutrients bioavailability. These types of changes could ultimately impact several biogeochemical cycles, as phytoplankton are responsible for almost half of the primary production on earth. Consequently, this study was designed to evaluate the impact of various concentrations (0μM, 20μM, 40μM, 80μM and 100μM) of several manufactured nanoparticles (gold, carbon and iron) on the dynamics of four economically important microalgae strains. Responses, such as chlorophyll content, protein, lipid content, lipid profile, biomass and cell morphology were monitored over a period of two weeks. No significant acute toxicity was exhibited within the first 24 hours of exposure. However, after 4 days, a remarkably high mortality rate was detected with increasing NPs concentrations of Fe60, C80 and Au60. Iron suspensions were found to be more toxic to the microalgae strains tested than those of Gold and Carbon under comparable regimes. Further investigations with other, either positively or negatively charged nanoparticles, should provide a deeper understanding on the impacts on these engineered materials in our ecosystems.