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This paper analyses the mechanical performance of pieces manufactured using PLA and ABS, the most commonly used materials in material extrusion 3D printing technologies. PLA is a biodegradable polymer derived from lactic acid. The main advantage of this material is how easy it is to use in 3D printing and the good results it delivers. It requires a lower extrusion temperature than ABS, it does not suffer significant distortions during printing and it adheres well to the platform, which means it does not require a heated base. Neither does it give off a bad smell or toxic vapours during printing. It must not be used for parts that have to withstand high temperatures because PLA tends to warp at over 60 °C. ABS is a thermoplastic that is extremely resistant to impact, abrasion, and chemical elements. In 3D printing, it is the most used material after PLA. Its good mechanical properties, resistance to temperature, low price, moderate flexibility, long service life and range of melting temperatures make this material an excellent option for manufacturing all manner of parts using FDM technologies, above all, parts that have to withstand cyclical loads and temperature changes. However, it is not suitable for all applications as it presents problems of contraction and warping during printing, tends to peel away from the platform, and tends to give off toxic gases. Table 1 shows the data provided by the manufacturer for the filaments of the two materials used. As can be seen, PLA is more rigid and has a greater tensile strength while ABS is more ductile. However, the impact strength of ABS is far greater (320 J/m against 220 J/m (Notched Izod Impact)), one of the main properties that differentiates it from other plastics.
The additive manufacturing equipment to be used is the Prusa I3 Aluminium printer (Prague, Czech Republic) (Figure 2a), which employs FFF technology. The Cura software (Ultimaker, Geldermalsen, The Netherlands) is used to export the three-dimensional models of the samples to G-code. The main technical characteristics of the FDM printer are defined in Table 2. The tests are carried out using a HOYTOM HM-D 100 kN model universal testing machine (Leioa, Spain) (Figure 2b).

Soil chemical properties were determined according to the methods of Bao (2000) . The potentiometric method was used to measure pH, water-soil ratio of 2.5:1(w/v); Organic matter (OM), Potassium dichromate oxidation volumetric method; Total nitrogen (TN), Alkaline hydrolysis diffusion method + semi micro Kjeldahl method; Total phosphorus (TP), Heating digestion method + Vanadium molybdate blue colorimetric method; Total potassium (TK), Heating digestion method + flame photometric method; Alkali hydrolyzed nitrogen (AN), Alkaline hydrolysis diffusion method + semi micro Kjeldahl method; Available phosphorus (AP), Sodium bicarbonate injection + Vanadium molybdate blue colorimetric method; Available potassium (AK), Ammonium acetate extraction + flame photometric method. The measured indicators of each soil sample (1–2 g) were measured five times in parallel, and the results were averaged.
Gas chromatography (GC) was used to quantify the bioactive compounds in C. migao fruit, including 1,8-Cineole, sabinene, limonene, and α-terpineol (Chen et al., 2021 (link)). The powder of C. migao samples was precisely weighed (1.00 g). Chromatographic conditions: the column was HP-5 capillary column (30 m × 320 mm, 0.25 μm); Carrier gas: high-purity nitrogen N₂; Flow rate: 1 ml⋅min⁻¹; Injection volume: 1 μl; Split ratio: 10:1, injector temperature: 200°C; temperature-rising program: the initial oven temperature was 50°C, and maintained for 3 min, raised the temperature to 85°C at 5°C⋅min⁻¹ and held for 2 min, raised the temperature to 90°C at 5°C⋅min⁻¹ and held for 2 min, raised the temperature to 160°C at 5°C⋅min⁻¹ and held for 0 min, raised the temperature to 220°C at 20°C⋅min⁻¹ and held for 0 min. Detector (FID) temperature: 235°C (Dai et al., 2013 (link)).
Analysis of variance (ANOVA) and Tukey T-test were employed to detect statistically significant differences (p < 0.05, p < 0.01) in these properties and compounds between samples using SPSS 22.0, Microsoft Excel 2010 and Origin 9.0 system software were used to analyze and map the data of soil chemical properties and fruit bioactive ingredients.

The stevia plants were obtained from seeds incubated in an aqueous solution of MEL prior to germination.
The seeds were surface-sterilized according to Simlat et al. [77 ] before treatment. Three concentrations of MEL were used: 5 μM (5 MEL), 100 μM (100 MEL), and 500 μM (500 MEL). For the control, the seeds were incubated in water (0 MEL). After incubation, half of the seeds were germinated in in vitro conditions on agar gel and the other half on agar gel supplemented with 50 mM of NaCl. After three weeks of germination experiment, seedlings were transferred to the Murashige and Skoog (MS) [78 ] medium for one month and then well-developed plantlets were transplanted into pots (15 × 15 cm) containing soil, peat, and sand in a 3:1:1 ratio. The plants used for analysis were grown for six months in controlled conditions (25 °C, fluorescent light with intensity expressed as Photosynthetic Photon Flux Density of 320 μmol m⁻²s⁻¹ for 16 h/day, and 70% ± 5% relative humidity; Adaptis-A1000AR, Conviron, Winnipeg, MB, Canada).

The concentrations of NIRB and DOX in samples were quantified using both HPLC–UV and MS analysis. Briefly, NIRB and DOX were extracted from liposome samples by tenfold dilution with methanol. The resultant samples were then centrifuged at 3000 RPM, 4 °C for 15 min in glass centrifuge tubes to separate extracted drug from lipid. The supernatant was then assayed directly for HPLC–UV or diluted accordingly for MS detection.
HPLC–UV analysis of samples was performed using an Agilent 1260 infinity series LC (Agilent Technologies, Santa Clara, CA, USA). Chromatographic separation was achieved using an Agilent Eclipse XDB-C18 column (4.6 × 150 mm, 5.0 μm) at 25 °C with a mobile phase composed of acetonitrile and methanol 50:50 (A) and 50 mM ammonium acetate, pH 4 (B). The initial mobile phase was 40% A with a flow rate of 1.0 mL/min, which was gradually increased to 55% A over 4 min. Following a 4-min equilibration, the composition was changed back to 40% A over a duration of 30 s. The mobile phase was then maintained for another 1.5 min until run completion. Detection of both drugs was achieved using an Agilent 1260 Infinity II Diode Array Detector with detection of NIRB and DOX at 310 nm and 480 nm wavelengths, respectively.
HPLC–MS analysis was performed using an Agilent 1260 infinity series LC equipped with an Agilent EC-C18 column (2.1 × 50 mm, 1.9 μM) heated to 40 °C. A gradient elution was applied using methanol (A) and water (B) both with 0.1% formic acid (v/v). The initial mobile phase was 75% A with a flow rate of 0.3 ml/min which was gradually decreased to 0% A over 4 min. This composition was maintained for another 6 min before it was rapidly changed back to 75% A where it was maintained for the remaining 3 min of the run.
Mass spectrometry detection of NIRB and DOX was achieved using a ThermoFisher Scientific TSQ Endura Triple Quadrupole Mass Spectrometer (Mississauga, ON, Canada). Analysis was performed on positive ion mode with optimal ion source settings as follows: spray voltage of 3500 V, sheath gas of 5 a.u., auxiliary gas of 2 a.u., and ion transfer tube temperature of 275 °C. Selected precursor ions for NIRB were m/z 321.2 → 180.0, 205.0, 207.0, 232.0, 304.083 while precursor ions for DOX were m/z 544.2 → 320.9, 345.9, 361.0, 378.9, 396.9. Collision energies ranged from 19.0 V to 42.0 V for NIRB and 11.2 V to 41.2 V for DOX.
The encapsulation efficiency of drug in liposomes was calculated using the following equation: $$\%EncapsulationEfficiency=\frac{DrugEncapsulated\left(\mathit{mg}\right)}{DrugAdded\left(\mathit{mg}\right)}\times 100\%$$