Rosario González-Mota

In this work we analyze the lime saturation module for different clay settings of raw material after raw grinding process by means of a multiwavelength Raman spectroscopy study, at excitation wavelengths of 450, 532, 633 and 780 nm. The data reveal that independently of the wavelength used, the results of the Raman shifts can be used to calculate the setpoint for controlling the alumina in the raw mix that needs to be adjusted to have the lime saturation within quality parameters, with a minimum variation compared with other techniques such as XRF and XRD, thus ensuring that the Clinker phases are formed under quality standards. The intensity ratios of Raman spectra were used to calculate LS values which were close to those obtained with the XRF technique. Therefore, this measurement approach can be used successfully as an effective and alternative non-destructive method to determine the LS of cement raw mix.

This study evaluates the potential of 3D-printed acrylonitrile butadiene styrene (ABS) and carbon fiber (CF) as sustainable alternatives to steel reinforcement in cement-based materials. The experimental program analyzed the compressive strength of cement pastes and concrete cylinders incorporating 3D-printed ABS and CF elements. Unreinforced cement pastes exhibited higher compressive strength than reinforced pastes, indicating limited reinforcement–matrix interaction. In concrete cylinders, ABS reinforcement increased compressive strength by approximately 3 to 7 MPa compared to steel, whereas CF reinforcement showed variable performance and did not consistently surpass the control specimens. ANOVA and Tukey tests confirmed the statistical significance of the results. The anisotropic response of ABS and CF, inherent to layer-by-layer deposition, was identified as a major factor influencing structural performance, particularly with respect to reinforcement orientation. The results indicate that ABS presents potential as an environmentally favourable alternative to steel in selected applications, while CF requires further optimization for compression-oriented use. Continued research is recommended to evaluate long-term durability, environmental resistance, and reinforcement–matrix compatibility in order to advance the implementation of polymer-based, additively manufactured reinforcements in construction materials.

Pleurotus ostreatus is a wood-decaying fungus capable of producing key enzymes for lignin degradation. Laccase (Lcc), manganese peroxidase (MnP), lignin peroxidase (LiP), and unspecific peroxygenase (UnP) activities of P. ostreatus grown on a wheat straw infusion medium enriched with malt extract and yeast extract (SMY) were studied. Growth kinetics and enzymatic parameters were also determined. Glucose medium was used as a control. The specific growth rate of P. ostreatus in SMY (0.62 h⁻¹) was more than twice as high as that shown in the control (0.24 h⁻¹). This fungus produced 5-fold higher biomass (15.7 g/L) in SMY medium than in the control (3 g/L). Lcc, MnP, LiP and UnP activities were approximately 67-,19-,11-, and 17-fold greater in SMY (3106, 4082, 1564, and 1883 U/L, respectively) than in the control (46, 213, 143, and 112 U/L respectively). P. ostreatus constitutively produced all the studied enzymes; however, the presence of wheat straw infusion components (i.e. phenolic compounds) in SMY enhanced the enzymes production. This is believed to be the first study to examine UnP production by P. ostreatus in an enriched natural medium. UnPs have been reported as promising enzymes for degradation of hazardous pollutants; however, there is still little information about their production.

Widely used petroleum-derived polymers, such as polyethylene (PE), are a significant source of environmental pollution due to their accumulation in the ecosystem. In the present study, P. ostreatus was grown in a PE-supplemented medium added with H2O2 as a peroxidase enzymeinducing agent for 5 weeks in liquid fermentation to evaluate the biodegradation of this polymer. A medium lacking H2O2 was used as a control. Enzyme production by P. ostreatus and the contact angle of the PE surface were evaluated. Chemical structural changes of the PE surface were determined by FTIR spectroscopy. The activities of laccase, unspecific peroxigenase, and lignin peroxidase were found to be higher in the control medium (4072, 3692 and 4224 U/L, respectively) than in the medium supplemented with H2O2 (3531, 2910 and 2878 U/L, respectively). Changes in the chemical structure and the decrease in the contact angle of the PE surface showed biodegradation of the polymer. The PE surface of control cultures had a lower contact angle (60.9°) than that observed in PE of cultures added with H2O2 (66.8°). The addition of 5 mM of H2O2 to the medium increased the production of manganese peroxidase, however, it did not have a significant impact on the biodegradation of PE.

Biodegradable plastics are eco-friendly materials that can be safely incorporated into the environment to reduce plastic pollution. In this work, Pleurotus ostreatus was grown in unirradiated (UnBPE) and UV-B irradiated low-density polyethylene films (IrBPE) commercially labeled as biodegradable for four weeks in liquid fermentation. Fungal growth, laccase (Lac), lignin peroxidase (LiP), unspecific peroxygenase (UnP), and manganese peroxidase (MnP) activities, and contact angle, as well as changes in the surface morphology and chemical structure of the samples using SEM and FTIR spectroscopy, respectively, were evaluated. Production of fungal biomass was similar in both IrBPE and UnBPE samples. P. ostreatus showed higher enzyme activities in IrBPE than in UnBPE. From all the enzymes tested, Lac had the highest activity (5836.69 U/L) followed by LiP (2789.15 U/L), UnP (2681.04 U/L), and MnP (983.37 U/L) in IrBPE. The lowest contact angle was observed at week four, decreasing from 67.33° to 50.66° for IrBPE. The FTIR surface spectra of the samples showed an increase in distinctive oxidation bands in the polymer chain, corresponding to functional groups such as carbonyls, vinyls, and hydroxyls. IrBPE showed fractures on its surface. Low-density polyethylene commercially labeled as biodegradable enhanced its biodegradation when exposed to pretreatment with UV-Bradiation.

Microplastics have become a global pollution issue due to their presence in several ecosystems such as oceans, coasts, rivers, and lakes, among others. However, there is no standardized protocol for detecting and quantifying microplastics in liquid samples; but also, most quantification methods rely on visual counting of microplastics suspended in a solid medium, typically filter paper. This study presents preliminary results of microplastic quantification in liquid samples through image analysis using ImageJ software and different threshold values. Polyethylene microplastic in liquid samples were prepared in the laboratory using virgin polyethylene microplastics dyed with Nile red, 1 µg mL-1, and HPLC-grade water. The statistical analysis of the results performed using the Anderson-Darling normality test in Minitab® software, version 18.1, shows that this protocol is reliable for concentrations of up to 16 microplastics, with a 95% confidence interval. These results demonstrate the reliability of the proposed method for the quantification of microplastics in liquid samples.

This work presents the results by irradiating fresh Portland cement pastes with CO₂ laser, at powers of 1.6, 2.0, and 2.4 W, at different water‐to‐cement (w/c) ratios 0.4, 0.45, and 0.5. Raman spectra show the evolution and accelerated growth of the main hydration products through the intensity changes of the Raman signal. The Raman shifts reveal that the C‐S‐H, CH, AFt, and CaCO₃ bands are detected in a shorter time, which means that the setting times are also reduced. The detected band of calcium carbonate, which is due to the incorporation of limestone during the grinding process, shows that it is responsible largely for the acceleration in the reactions during the hydration of the cement. The Raman signals of the hydration products of nonirradiated cement pastes present a delay in their evolution with respect to the irradiated pastes. The curves obtained from the Raman spectra can be used to model the mechanism of hydration as well as to understand the setting process.

Different types of commercial polyethylene films, low‐density polyethylene (LDPE), high‐density polyethylene (HDPE), and biodegradable polyethylene (BIO‐PE), were exposed to UV‐B radiation at different exposure time and domestic composting during spring and fall at ambient conditions. The effects of UV‐B radiation and domestic composting on LDPE, HDPE, and BIO‐PE degradation were characterized by FTIR spectroscopy. LDPE, HDPE, and BIO‐PE exposed to UV‐B radiation underwent photo oxidation reactions leading to the formation of carbonyl (CO) and vinyl (CH₂CH) groups and hydrophilic surface modification. Also, the exposure of LDPE, HDPE, and BIO‐PE to domestic composting at ambient conditions at different seasons suffered biodegradation reactions leading to the formation of polysaccharides. In both different seasons LDPE, HDPE, and BIO‐PE underwent partial biodegradation, remaining in the domestic composting as unwanted polymer debris. However, biodegradation in domestic composting is not recommended as feasible disposal routes for nonbiodegradable and commercially labeled as biodegradable PE.

Thermooxidation of LDPE films by CO₂ laser radiation, 10.6 μm, was characterized by Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR). The formation of carbonyl and hydroxyl functional groups onto LDPE films was dependent on the fluency of CO₂ laser. IR absorption of vinyl groups and C-O bond present in alcohols showed a decrease and an increase, respectively, indicating that CO₂ laser radiation causes simultaneous formation and accumulation of hydroperoxides in LDPE films; furthermore, crystallinity of LDPE films irradiated with CO₂ tends to increase. So, CO₂ laser radiation is able to oxidize the LDPE films, obtaining a PE with similar spectroscopic properties to that of PE-BIO by a physical process.