Full Factorial Experimental Design Research Articles

Rational development of fingolimod nano-embedded microparticles as nose-to-brain neuroprotective therapy for ischemic stroke.

Ischemic stroke is one of the major diseases causing varying degrees of dysfunction and disability worldwide. The current management of ischemic stroke poses significant challenges due to short therapeutic windows and limited efficacy, highlighting the pressing need for novel neuroprotective treatment strategies. Previous studies have shown that fingolimod (FIN) is a promising neuroprotective drug. Here, we report the rational development of FIN nano-embedded nasal powders using full factorial design experiments, aiming to provide rapid neuroprotection after ischemic stroke. Flash nanoprecipitation was employed to produce FIN nanosuspensions with the aid of polyvinylpyrrolidone and cholesterol as stabilizers. The optimized nanosuspension (particle size = 134.0 ± 0.6nm, PDI = 0.179 ± 0.021, physical stability = 72 ± 0h, and encapsulation efficiency of FIN = 90.67 ± 0.08%) was subsequently spray-dried into a dry powder, which exhibited excellent redispersibility (RdI = 1.09 ± 0.04) and satisfactory drug deposition in the olfactory region using a customized 3D-printed nasal cast (45.4%) and an Alberta Idealized Nasal Inlet model (8.6%) at 15L/min. The safety of the optimized FIN nano-embedded dry powder was confirmed in cytotoxicity studies with nasal (RPMI 2650 and Calu-3 cells) and brain related cells (SH-SY5Y and PC 12 cells), while the neuroprotective effects were demonstrated by observed behavioral improvements and reduced cerebral infarct size in a middle cerebral artery occlusion mouse stroke model. The neuroprotective effect was further evidenced by increased expression of anti-apoptotic protein BCL-2 and decreased expression of pro-apoptotic proteins CC3 and BAX in brain peri-infarct tissues. Our findings highlight the potential of nasal delivery of FIN nano-embedded dry powder as a rapid neuroprotective treatment strategy for acute ischemic stroke.

Enhanced high-temperature mechanical properties and strengthening mechanisms of chemically prepared nano-TiC reinforced IN738LC via laser powder bed fusion

Fabrication of high-strength nickel-based composites to meet the demanding service requirements in aerospace environments is a significant challenge. This paper introduces the wet chemical method to prepare the nano-TiC reinforced IN738LC. In contrast to the conventional ball milling approach, this method attains superior attachment of nanoparticles. By employing a full-factorial experimental design, the correlation between Laser-powder bed fusion (L-PBF) processing parameters and the porosity, micro-hardness, and high-temperature tensile strength of as-built samples was examined. The results indicate that the optimal processing parameters are a laser power of 225 W, scanning speed of 750 mm/s, and hatch space of 0.09 mm, with a Volumetric energy density (VED) of 111.1 J/mm3. Compared to IN738LC, the chemically prepared TiC-IN738LC exhibits a 45 % increase in room temperature tensile strength (400 MPa) and a 65 % increase in high-temperature tensile strength (120 MPa). Compared with ball-milled TiC-IN738LC, the chemically prepared samples present superior microstructure with more equiaxed grains. The morphological analysis of the tensile samples reveals that the presence of dimples are crucial in enhancing the ductility properties. Furthermore, this study identifies the Orowan strengthening mechanism and the grain refinement strengthening mechanism as the principal mechanisms of reinforcement by nano-ceramics.

A Novel Modeling Optimization Approach for a Seven-Channel Titania Ceramic Membrane in an Oily Wastewater Filtration System Based on Experimentation, Full Factorial Design, and Machine Learning.

This comprehensive study looks at how operational conditions affect the performance of a novel seven-channel titania ceramic ultrafiltration membrane for the treatment of produced water. A full factorial design experiment (23) was conducted to study the effect of the cross-flow operating factors on the membrane permeate flux decline and the overall permeate volume. Eleven experimental runs were performed for three important process operating variables: transmembrane pressure (TMP), crossflow velocity (CFV), and filtration time (FT). Steady final membrane fluxes and permeate volumes were recorded for each experimental run. Under the optimized conditions (1.5 bar, 1 m/s, and 2 h), the membrane performance index demonstrated an oil rejection rate of 99%, a flux of 297 L/m2·h (LMH), a 38% overall initial flux decline, and a total permeate volume of 8.14 L. The regression models used for the steady-state membrane permeate flux decline and overall permeate volume led to the highest goodness of fit to the experimental data with a correlation coefficient of 0.999. A Multiple Linear Regression method and an Artificial Neural Network approach were also employed to model the experimental membrane permeate flux decline and analyze the impact of the operating conditions on membrane performance. The predictions of the Gaussian regression and the Levenberg-Marquardt backpropagation method were validated with a determination coefficient of 99% and a Mean Square Error of 0.07.

Improvement of fluorescence properties by surface modification of CdS-ZnS quantum dots by thiol compounds and its application as a sensitive fluorescence probe for copper ion detection.

The capped CdS-ZnS quantum dots (QDs) were synthesized with various thiol capping agents of glycolic acid (TGA), mercaptosuccinic acid (MSA), and L-cysteine (LCY) and used as fluorescence probe for determination of Cu (II) ions. The method of two-level three-factor full-factorial experiment design was used to achieve the best optical fluorescence emission. Results revealed that Cu (II) ions can effectively quench the emission of QDs, and the fluorescence intensity is linearly decreased with increasing Cu (II) ion concentration. The limit of detection for CdS-ZnS@ QDs capped with TGA, MSA, and LCY was obtained at 1.15 ×10-7, 1.32 ×10-7, and 2.19 ×10-7mol L-1, respectively, with linear dynamic range of 3.13 ×10-6 to 1.41 ×10-4mol L-1. Luminescence quantum yields of CdS-ZnS@LCY, CdS-ZnS@MSA, and CdS-ZnS@TGA were obtained at 4.17, 1.92, and 2.47, respectively. Results indicated that no significant quenching occurred in the presence of the other metal ions. The binding constant (Kb) of capped CdS-ZnS@ QDs with Cu2+ and the other metal ions was also investigated and discussed. The Kb value for Cu2+ was obtained considerably more than that the other ions. This work presents a new and sensitive method for determination of Cu2+ ion.

Influence of Defects and Microstructure on the Thermal Expansion Behavior and the Mechanical Properties of Additively Manufactured Fe-36Ni.

Laser-based powder bed fusion of metals (PBF-LB/M) is a widely used additive manufacturing process characterized by a high degree of design freedom. As a result, near fully dense complex components can be produced in near-net shape by PBF-LB/M. Recently, the PBF-LB/M process was found to be a promising candidate to overcome challenges related to conventional machining of the Fe64Ni36 Invar alloy being well known for a low coefficient of thermal expansion (CTE). In this context, a correlation between process-induced porosity and the CTE was presumed in several studies. Therefore, the present study investigates whether the unique thermal properties of the PBF-LB/M-processed Fe64Ni36 Invar alloy can be tailored by the selective integration of defects. For this purpose, a full-factorial experimental design, representing by far the largest processing window in the literature, was considered, correlating the thermal expansion properties with porosity and hardness. Furthermore, the microstructure and mechanical properties were investigated by scanning electron microscopy and quasi-static tensile tests. Results by means of statistical analysis reveal that a systematic correlation between porosity and CTE properties could not be determined. However, by using specific process parameter combinations, the microstructure changed from a fine-grained fan-like structure to a coarse columnar structure.

Improving building natural ventilation simulation accuracy: calibration of standard k − ε closure coefficients using design of experiment

Abstract The objective of this study is to improve the accuracy of the standard k − ε (SKE) turbulence model for natural ventilation simulation, a critical component in the analysis and design of energy-efficient buildings. The methodology involves generating 17 design points for the four closure coefficients (C ɛ 1,C ɛ 2,C µ ,σ k ) for the SKE model using 2k full-factorial design of experiment (DOE) with a centre point. A sheltered single storey-building with windward and leeward openings is modelled and simulated using computational Fluid Dynamics (CFD) to obtain the Root Mean Square Error (RMSE) and Factor of two observation (FAC2) for each design point. Response models for RMSE and FAC2 are then generated, and optimization is employed to maximize FAC2, minimize RMSE, and the combination of both. The results are validated and compared with experimental and simulation data reported in existing literature. The findings indicate that the indoor velocity profiles with closure coefficients obtained by maximizing FAC2 are better aligned with the actual experimental results. Compared with the existing calibration method, the proposed calibration method can yield superior results with fewer sampling points, highlighting the efficiency of the proposed approach. The calibration framework developed in this study can be extended to other simulation scenarios, contributing to the robust and efficient modelling of natural ventilation systems in various contexts. This research presents a novel calibration method for the SKE model in natural ventilation simulation, providing a more accurate and efficient approach compared to existing methods. The results have important implications for researchers and practitioners working in the field of building energy simulation and sustainability.

Optimizing wind-catching butterfly roofs to improve cross natural ventilation performance in apartment buildings

Abstract This study aims to enhance cross natural ventilation performance in multi-level double-loaded apartments by employing a wind-catching butterfly roof, specifically designed for apartments with a center-to-center opening configuration. A 2k full-factorial design of experiment (DOE) method with a center point is utilized for design optimization. Nine configurations, determined by roof height h and roof angle α, are assessed using Computational Fluid Dynamics (CFD). After the initial DOE assessment, three additional butterfly roof designs with varying α values are explored. The dimensionless flow rate (DFR) serves as the objective function for optimization. The optimal design features a butterfly roof with h = 0.01m and α = 30°, demonstrating improvements of 2.5%−4.9% in DFR and 5.3%−9.0% in the pressure coefficient C p compared to scenarios without a butterfly roof. Butterfly roofs also increased the velocity magnitudes in the rooms of the leeward block, with configurations h = 0.01m and α = 35° and 37.5° showing the most significant increases of 58.5% − 86.9% on levels 1 to 3. The discharge coefficient C d induced by all butterfly roof configurations are within 0.6 − 0.7 on levels 1 to 3, while the C d values for levels 4 to 6 are within 0.5 − 0.6. Although butterfly roofs can enhance indoor air quality, they require further research to meet all recommended guidelines. These findings provide valuable insights for architects and urban planners aiming to reduce the environmental footprint of apartment buildings. This research presents a comprehensive evaluation of the potential of butterfly roofs to enhance apartment ventilation and offers recommendations for future design improvements.

A novel machine learning method for the design optimization of diamond waveguides fabricated by femtosecond laser writing

We report on a novel machine learning method for the design optimization of femtosecond (fs) laser written dielectric waveguides. Experimental results previously obtained from the optical characterization of fs laser written depressed cladding diamond waveguides have been used to form statistically generated regression models. Design variables such as core diameter and number of written tracks were varied to both minimize the propagation loss as well as to establish a full-factorial experimental design. The regression models were used to conduct a multi-objective optimization study to optimize the competing objectives such as maximizing the refractive index contrast while minimizing the propagation loss and V-number by using a genetic algorithm. Optimization was subject to a nonlinear Rayleigh range constraint to ensure that the structure was in the waveguiding regime. Results from the optimization revealed the optimum variables to achieve low-loss and nearly single-mode guiding for a fs laser written diamond waveguide. Using the solution sets of design parameters resulting from the optimization study and their corresponding objective function values, important correlations between the design parameters and the objective functions have been revealed. With this regard, it has been shown that the number of written tracks is a much more dominant parameter, when compared to core diameter, during the design of a fs laser written circular depressed cladding diamond waveguide. The proposed method should be applicable not only to diamond waveguides but also to a wide range of dielectric waveguides fabricated by fs laser writing.

Experimental Heat Transfer Analysis of a New Turbulator in a Concentric Heat Exchanger Tube: A Full Factorial Design Approach

Abstract People have been looking for alternative energy sources because current sources may be depleted. Furthermore, it is critical to utilize available energy sources as effectively as possible. Turbulators are among the topics to consider when it comes to energy efficiency. In practice, turbulators are often used in exchangers to enhance heat transfer. Putting newly constructed turbulators in determined locations of the constant surface temperature heat exchanger, velocity, temperatures, pressure, and flow measurements have been performed in the inlet and outlet. In the case of using different numbers of turbulators, their placement in different locations, their arrangement at different distances, and their use at different Reynolds, the changes in pressure drop, Nusselt number, friction factor, efficiency, exergy loss rate, and NTU were determined with the full-factor experimental design. When the test data were evaluated, it was seen that as the number of turbulators increased, the thermal efficiency, friction factor, and pressure loss also increased. Using turbulators in different numbers, at different positions, at different distances, and with different Reynolds numbers, the effect ratio on the pressure loss, Nusselt number, and friction factor parameters was detected. In the analyses made, the most efficient parameters on heat transfer were determined, respectively, as Reynolds number (64.55%), the position of turbulators (19.73%), the distance between turbulators (6.09%), and the number of turbulators (5.94%).

Effect of pulsed electric field processing on the quality characteristics and enzyme activity of tender coconut water.

Tender coconut water (TCW) is a natural drink rich in natural electrolytes, minerals, salts and sugars; it has good health benefits. But, its shelf-life is very limited because of the active nature of enzymes present in it when exposed to air. Therefore, the processing of TCW is necessary to inactivate the enzymes. So, this study aims to observe the effect of various process parameters of pulsed electric field (PEF) on the quality parameters of TCW. For the treatment of TCW with PEF, a full-factorial design of experiments was followed with process parameters such as three levels of electric field intensity (8, 12, and 16 kV/cm), two levels of pulse width (PW) (50 and 70 μs), and six levels of the number of pulses (2000 to 12,000 pulses) were considered at a constant pulse OFF time of 75 ms. PEF treatment did not significantly change pH, total soluble solids, and viscosity. However, it significantly affected vitamin C, colour, and total and reducing sugars. PEF treatment significantly enhanced the total phenolic content and antioxidant activity by 23.17% and 42.49%, respectively. At the same time, significant inactivation of polyphenol oxidase (100%) and peroxidase (60.2%) was observed at PEF treatment conditions of 16 kV/cm, 70 μs PW, and 12,000 pulses. Moreover, no significant change in the sensory acceptability of PEF-treated TCW (16 kV/cm, 70 μs PW, 12,000 pulses) when compared to the untreated/fresh TCW, which is a promising sign.

Experimental study on preparation and performance of the Corn Straw Fiber (CSF) reinforced EPS concrete

With the full factor experimental design method carried out, 20 sets of EPS concrete specimens with different mass fractions of Corn Straw Fiber (CSF) and Expanded-Polystyrene (EPS) particles were designed to study their density, water absorption, compressive strength, flexural strength, splitting tensile strength, mass loss and strength loss after freeze-thaw cycles, and changes in thermal conductivity, to evaluate the effect of CSF content and EPS content on the properties of EPS cement-based composites. The experimental results show that adding CSF can improve the mechanical properties of EPS concrete while reducing its density, the maximum increase rate of compressive strength is 69.7 %, with a maximum value of 1.12 MPa; The maximum improvement rate of flexural strength is 127.38 %, with a maximum value of 0.885 MPa; The maximum improvement rate of splitting tensile strength is 68.07 %, and the maximum value is 0.256 MPa. After 50 standard freeze-thaw cycles, straw fibers can delay the quality loss of EPS concrete, but show adverse effects on its strength loss, the maximum quality loss rate is 4.23 %, and the maximum loss rates for the three strengths are 24.46 %, 24.22 %, and 24.61 %, respectively. In addition, in terms of improving the thermal insulation performance of EPS concrete, the role of the two aggregates is manifested as EPS > CSF, and the thermal conductivity coefficient values under different aggregate dosages were obtained, when the content of EPS is 1.4 % and the content of CSF is 4 %, the minimum thermal conductivity value is 0.0402 W/(m·°C), and the thermal conductivity coefficient of calcium silicate board is 0.0378 W/(m °C) by the thermal conductivity coefficient formula of composite materials. which can serve as a reference for selecting building insulation materials in areas with high temperature differences.

Investigation of tool wear and energy consumption in machining Ti6Al4V alloy with uncoated tools

This research studies the energy consumption and wear mechanism of carbide cutting tools in dry machining of Ti6Al4V alloy. In the first phase of experiments, full factorial design experiments were employed to study the tool wear rate (R) and specific cutting energy (SCE) with respect to the machining conditions (cutting speed and feed rate). Results showed that machining responses such as tool wear and energy consumption are affected by cutting conditions, thus requiring investigation to understand the wear mechanisms. Therefore, in the second phase, additional experiments were performed to investigate the tool-workpiece interactions at the cutting conditions reported to have low, moderate, and high tool wear. It was revealed that strong adhesion and material transfer between the tool and workpiece caused high wear. Electron dispersive X-ray spectroscopy (EDX) analysis of worn tools showed that the transfer of tungsten (W) and cobalt (Co) to the workpiece and titanium to the tool surface is the primary cause of tool deterioration. As a result, diffusion and dissolution have degraded cutting performance and weakened the tool edge, leading to rapid wear. Furthermore, worn tools resulted in relatively higher energy consumption per unit volume of material removed at the tooltip. The degradation of cutting performance and weakening of the tool edge results in rapid wear and higher energy consumption. The study suggests that minimizing tool wear is crucial for energy reduction, improved sustainability, and cleaner production goals in dry machining of titanium-based alloys.

The Effects of Incorporating Nanoclay in NVCL-NIPAm Hydrogels on Swelling Behaviours and Mechanical Properties.

Following the formulation development from a previous study utilising N-vinylcaprolactam (NVCL) and N-isopropylacrylamide (NIPAm) as monomers, poly(ethylene glycol) dimethacrylate (PEGDMA) as a chemical crosslinker, and Irgacure 2959 as photoinitiator, nanoclay (NC) is now incorporated into the selected formulation for enhanced mechanical performance and swelling ability. In this research, two types of NC, hydrophilic bentonite nanoclay (NCB) and surface-modified nanoclay (NCSM) of several percentages, were included in the formulation. The prepared mixtures were photopolymerised, and the fabricated gels were characterised through Fourier transform infrared spectroscopy (FTIR), cloud-point measurements, ultraviolet (UV) spectroscopy, pulsatile swelling, rheological analysis, and scanning electron microscopy (SEM). Furthermore, the effect of swelling temperature, NC types, and NC concentration on the hydrogels' swelling ratio was studied through a full-factorial design of experiment (DOE). The successful photopolymerised NC-incorporated NVCL-NIPAm hydrogels retained the same lower critical solution temperature (LCST) as previously. Rheological analysis and SEM described the improved mechanical strength and polymer orientation of gels with any NCB percentage and low NCSM percentage. Finally, the temperature displayed the most significant effect on the hydrogels' swelling ability, followed by the NC types and NC concentration. Introducing NC to hydrogels could potentially make them suitable for applications that require good mechanical performance.

Experimental study on ultrasonic assisted milling effect on blade distortion

Distortion in milling is a prevalent issue that can arise during material machining. It stems from the forces exerted by the cutting tool on the machined material, resulting in uneven material removal and subsequent warping of the parts. The distortion can be prevented with proper cutting speed, feed rate, and tool selection. Ultrasonic-Assisted Milling (UAM) mitigates distortion in milling processes by optimizing cutting conditions. This machining technique employs high-frequency vibrations to efficiently remove material from a workpiece. In this study, 18 tests according to a full factorial design experiment were used to investigate cutting force and distortion in two modes of conventional milling and ultrasonic-assisted milling. Our findings reveal a direct correlation between cutting force and distortion in UAM. Specifically, UAM exhibited a significant reduction of approximately 28.4% in cutting force compared to conventional milling (CM). Furthermore, distortion in UAM was diminished by about 34.06%. Additionally, a noteworthy improvement of 28.4% in surface roughness was observed. These results collectively help produce accurate workpieces and ensure the production of undamaged and warp-free parts.

The effects of protein supplementation, fumagillin treatment, and colony management on the productivity and long-term survival of honey bee (Apis mellifera) colonies.

In this study, we intensively measured the longitudinal productivity and survival of 362 commercially managed honey bee colonies in Canada, over a two-year period. A full factorial experimental design was used, whereby two treatments were repeated across apiaries situated in three distinct geographic regions: Northern Alberta, Southern Alberta and Prince Edward Island, each having unique bee management strategies. In the protein supplemented treatment, colonies were continuously provided a commercial protein supplement containing 25% w/w pollen, in addition to any feed normally provided by beekeepers in that region. In the fumagillin treatment, colonies were treated with the label dose of Fumagilin-B® each year during the fall. Neither treatment provided consistent benefits across all sites and dates. Fumagillin was associated with a large increase in honey production only at the Northern Alberta site, while protein supplementation produced an early season increase in brood production only at the Southern Alberta site. The protein supplement provided no long-lasting benefit at any site and was also associated with an increased risk of death and decreased colony size later in the study. Differences in colony survival and productivity among regions, and among colonies within beekeeping operations, were far larger than the effects of either treatment, suggesting that returns from extra feed supplements and fumagillin were highly contextually dependent. We conclude that use of fumagillin is safe and sometimes beneficial, but that beekeepers should only consider excess protein supplementation when natural forage is limiting.

Machining efficiency and geometrical accuracy on micro-EDM drilling of titanium alloy

ABSTRACT In the current study, micro-electric discharge drilling (µEDD) is conducted on a titanium grade 2 alloy using a tungsten carbide (WC) tool electrode of 496 µm diameter. Capacitance, voltage, and feed rate are selected as machining variables to conduct the experiments based on the full factorial experimental design method. Overcut, material removal rate (MRR), circularity, and hole taper are considered as performance measures. Furthermore, overall evaluation criteria (OEC) is utilized for multiple-objective optimization by allotting varying and equal weight percentages to each response measure. The results of OECs are compared with a revolutionary heuristic multi-objective genetic algorithm (MOGA), resulting in a similar optimal parametric combination and close response measures are obtained. Micrographic investigation demonstrates that at lower capacitance and voltage levels, there is less burr formation, recast layer, and circularity error. Moreover, FESEM and EDS analyses are employed to investigate the machined surface topology and elemental composition respectively.

Hematite-Gamma Alumina-based Solid Catalyst Development for Biodiesel Production from Palm Oil

This research investigated the performance of hematite-gamma alumina (Fe2O3/γ-Al2O3) catalyst in biodiesel production from palm oil. A full factorial experimental design was utilized to analyze the effect of hematite content, catalyst loading, and methanol-to-oil ratio on catalyst performance. From the experiment, biodiesel in the range of 73.6 to 87.6% FAME content was obtained. It was concluded that the catalyst composition, the methanol-to-oil ratio, and the catalyst loading have a significant effect on the FAME content of the biodiesel. Hematite has strong affinity for fatty acids, so a larger hematite surface area will result in a higher fatty acid absorption capacity. The addition of excess methanol can reduce the contact inhibition between the reactants and the active site of the catalyst, thereby increasing the conversion rate of the reaction. Moreover, a higher amount of catalyst loading can result in an increase in the FAME content when accompanied by an increase in the hematite content of the catalyst.

Thermo-Mechanical Characterization of Metal-Polymer Friction Stir Composite Joints-A Full Factorial Design of Experiments.

With the increasing demand for lighter, more environmentally friendly, and affordable solutions in the mobility sector, designers and engineers are actively promoting the use of innovative integral dissimilar structures. In this field, friction stir-based technologies offer unique advantages compared with conventional joining technologies, such as mechanical fastening and adhesive bonding, which recently demonstrated promising results. In this study, an aluminum alloy and a glass fiber-reinforced polymer were friction stir joined in an overlap configuration. To assess the main effects, interactions, and influence of processing parameters on the mechanical strength and processing temperature of the fabricated joints, a full factorial design study with three factors and two levels was carried out. The design of experiments resulted in statistical models with excellent fit to the experimental data, enabling a thorough understanding of the influence of rotational speed, travel speed, and tool tilt angle on dissimilar metal-to-polymer friction stir composite joints. The mechanical strength of the composite joints ranged from 1708.1 ± 45.5 N to 3414.2 ± 317.1, while the processing temperature was between 203.6 ± 10.7 °C and 251.5 ± 9.7.

Development of a Green, Quick, and Efficient Method Based on Ultrasound-Assisted Extraction Followed by HPLC-DAD for the Analysis of Bioactive Glycoalkaloids in Potato Peel Waste.

α-Solanine and α-chaconine are the two most predominant glycoalkaloids (GAs) present in potato. Potato peel contains a high concentration of GAs, which are especially interesting for application in the pharmaceutical industry due to their different beneficial properties (such as anticarcinogenic, anti-inflammatory, antiallergic, antipyretic, antiviral, fungicide, and antibiotic activities, among others); so, potato peel waste can be valorized by extracting these biologically active compounds. For this, a green, quick, and efficient miniaturized analytical approach based on ultrasound-assisted extraction (UAE) combined with HPLC-DAD was developed to quantify α-solanine and α-chaconine in potato peel. Some parameters of the extraction were optimized, including the extraction method, the type of solvent, and the sample/solvent ratio, by a three-factor, three-level (33) full factorial experimental design. The optimal extraction conditions were obtained with UAE using methanol as a solvent and a sample/solvent ratio of 1:10 (w/v, g/mL). The analytical greenness metric for sample preparation (AGREEprep) tool was used to assess the greenness of the methods used. The tool revealed an acceptable green analysis, with 0.61 points. The method was validated and applied to the evaluation of GAs in the peel of 15 commercial varieties of potato. The amount of glycoalkaloids found in the samples evaluated ranged from 143 to 1273 mg/kg and from 117 to 1742 mg/kg dry weight for α-solanine and α-chaconine, respectively. These results reveal the important variability that exists between potato varieties; so, their analysis is of great importance to select the most suitable ones for biovalorization (e.g., the Amandine and Rudolph varieties, with around 3000 mg/kg, in total, of both GAs). To provide higher stability to the peel during storage, freeze-drying or a medium-temperature drying process resulted preferable to avoid GA degradation. Overall, this study will contribute to the expansion of the future biovalorization of potato peel waste as well as provide a powerful analytical tool for GA analysis.

Maximizing the potential of commercial zinc stearate for one-pot esterification and transesterification for high-acidity biodiesel production

Meeting the growing demand for energy while combating the adverse effects of global warming remains challenging today, and biodiesel offers a potential solution to help mitigate the impact of global warming. In this scenario, our primary goal was to optimize biodiesel production from highly acidic soybean oil using a one-pot esterification and transesterification process, addressing the challenges associated with high-acidity substrates. To start, X-ray Diffraction (XRD) guaranteed us just one phase for each commercial catalyst, and we conducted catalytic experiments to select the most suitable Zn-based material for the process, choosing zinc stearate (ZnSt2) as the best candidate. Our study demonstrated that a nano-sized zinc oxide (ZnO) catalyst, which was anticipated to be the most suitable choice, did not exhibit optimal performance. Subsequently, a Full Factorial Design of Experiments (DOE) was employed to optimize reaction parameters, specifically, the reaction temperature and the oil-to-methanol (O:M) molar ratio. The results consistently showed that increased O:M ratio and temperature promoted enhanced fatty acid methyl esters (FAME) production and reduced acidity. Then, experiments were conducted to maximize FAME production and minimize free fatty acid (FFA) content. The results showed that increasing the catalyst concentration from 5 wt% to 10 wt% did not significantly impact FAME production or acidity reduction. Also, while increased methanol should theoretically enhance FAME production and reduce acidity, the results were inconsistent across all experiments. Excess methanol interfered with glycerol separation, leading to decreased FAME yield. Thus, this study underscores the complexity of biodiesel production and highlights the importance of selecting suitable catalysts and optimizing process parameters.