Search Results (765)

This work presents an intrinsic optical fiber sensor based on plasmonic phenomena in modified plastic optical fibers (POFs). The sensing area is achieved by replacing the polymethyl methacrylate (PMMA) core with a molecularly imprinted polymer (MIP) containing gold nanorods (GNRs). Thus, in the sensing area, the MIP acts as both a selective recognition element and an optically sensitive guiding medium where plasmonic phenomena occur. This optical–chemical configuration has been developed as a proof-of-concept for the detection of furfural in aqueous solution. The proposed sensor achieves a limit of detection (LOD) of 27 pM, demonstrates high selectivity for the analyte of interest, and is applicable even in real-world scenarios, as demonstrated by experimental results (a commercially available infant milk). The proposed sensor presents a significant enhancement of the sensor response, of about six orders of magnitude, compared to a conventional configuration where the same (or a similar) mixture of MIP/GNRs is spun over the exposed PMMA of a D-shaped POF area for comparison. Notably, even if this study has been carried out via a proof-of-concept in furfural detection, this substantial improvement is achieved while preserving a simple, portable, and cost-effective optical setup, highlighting the potential of this sensing strategy for the development of highly selective sensors by changing the MIP template. Full article

Variations in sweetness and bitterness among Madhuca longifolia flowers strongly influence their processing value and market acceptance, yet the chemo-diversity underlying these traits remains poorly characterized. This study aimed to unravel accession- and stage-specific differences by integrating physico-biochemical, elemental, and metabolic profiling across thirteen accessions (BM-1 to BM-13) from BUAT, Banda. Sensory and textural evaluations revealed wide diversity, with BM-5 displaying superior sweetness and aroma, whereas BM-6, BM-7, and BM-10 were differentiated by firmness, elasticity, and gumminess. Biochemical analyses across flower development showed that BM-5 consistently maintained higher sugars and β-carotene, while BM-1 exhibited marked reductions in sugars and total phenolics content; meanwhile, antioxidant activity increased with maturity, with BM-5 remaining the most stable. ICP-MS elemental analysis confirmed BM-5 as mineral-rich compared with lower-performing accessions. GC-MS metabolomic profiling of contrasting accessions (BM-1 and BM-5) across stages identified 303 volatile and semi-volatile metabolites, and multivariate analyses (PCA, VIP, volcano plots, pathway enrichment) revealed distinct stage- and accession-dependent patterns. Mature BM-5 was enriched in fermentation- and aroma-related metabolites such as melibiose, furfural, 5-HMF, and furaneol, whereas BM-1 accumulated defense-linked compounds including catechol, benzyl nitrile, and maltol. Overall, the integrated chemo-diversity landscape identifies BM-5 as a superior accession with high processing potential and value-addition prospects. Full article

In this work, the activity of vanadium-doped and undoped phosphomolybdic acids with general formulae H_3+nPMo_12−nV_nO₄₀ (n = 0, 1, 2, and 3) was evaluated in the acetalization of furfural with alkyl alcohols. The main focus was to assess how vanadium charge affects the catalytic activity of phosphomolybdic acid and to link these effects to changes in structural properties. The main reaction parameters, such as charge and concentration of the catalyst, temperature, time, type of alcohol and aldehyde, and charges of vanadium and of H⁺ ions, were studied. Various Brønsted acids (sulfuric, p-toluenesulfonic, undoped, and doped phosphomolybdic acids) were evaluated on the condensation reactions of furfural with methyl alcohol. Notably, H₄PMo₁₁VO₄₀ was the most active and selective catalyst for the formation of methyl acetal furfural. Water has a leveling effect on the strength of these acids. Nonetheless, under reaction conditions, the presence of vanadium affected their acidity strength, and it was possible to verify that the vanadium-monosubstituted phosphomolybdic acid was the strongest. The superior performance of H₄PMo₁₁VO₄₀ was attributed to its additional acidity, resulting from the presence of very strong Brønsted acid sites (H⁺) and Lewis acid sites, due to the inclusion of V⁵⁺ ions in its structure. The novelty of this work is the assessment of vanadium-doped phosphomolybdic acids in the homogeneous phase in the condensation reactions of furfural with various alcohols and of methyl alcohol with various aldehydes. Full article

The growing global demand for sustainable biotechnological routes for bioenergy production has paved the way for Brazil to position itself as a strategic leader due to its vast agricultural production and, consequently, agricultural residues, among which rice husk stands out. Although rice husk is widely used for energy cogeneration, its potential for producing high-value platform chemicals remains underexplored. This study aims to evaluate the production of value-added pyrolytic derivatives from rice husk by investigating the synergy between acid pretreatments and fast pyrolysis temperatures (350–600 °C). Thus, the experimental strategy involved intensifying the production of target compounds in the condensable fraction (bio-oil) from pyrolysis gases using different biomass pretreatments before fast pyrolysis according to the following conditions: (i) acid washing using acetic acid (10%), (ii) acid washing using nitric acid (0.1%) followed by impregnation using sulfuric acid (0.1–0.3%), and (iii) impregnation using sulfuric acid alone (0.1–0.3%). Fast pyrolysis was carried out over a temperature range of 350–600 °C using a pyroprobe microreactor coupled to a mass spectrometer (GC/MS). The best results, regarding overall volatile fraction, were observed when impregnation with 0.3% sulfuric acid was used prior to pyrolysis at 600 °C, resulting in around an 8.88-fold increase compared with untreated biomass. Nevertheless, the experimental conditions that favored the formation of our main chemical targets, such as levoglucosan, furfural and some phenols, were different. For instance, levoglucosan, furfural and eugenol increased by 21-, 10- and 22-fold, respectively, for biomass treated with HNO₃ (0.1%)/H₂SO₄ (0.2%) at 450 °C, whereas phenol and 4-vinylphenol increased by 35- and 14-fold at 500 °C. These findings can be considered satisfactory, highlighting the potential of the thermochemical conversion process as a valuable tool for the production of high-value chemicals from agricultural waste like rice husk. Full article

Lignocellulose is the most abundant renewable biomass on Earth, and its efficient bioconversion is critical for achieving carbon neutrality, substituting fossil resources, and advancing sustainable biomanufacturing. However, furfural, a dominant inhibitor generated during lignocellulosic pretreatment, severely compromises microbial metabolism and fermentation performance. To date, no systematic review has comprehensively integrated the mechanisms of furfural-induced microbial toxicity with corresponding stress tolerance strategies. This review elaborates on three core themes: the multi-pathway toxic effects of furfural, intrinsic microbial tolerance mechanisms, and advanced strategies for constructing a high-tolerance microbial chassis. Despite considerable progress, several research gaps persist, including poorly understood synergistic or antagonistic interactions between furfural and other hydrolysate inhibitors, insufficient integration of adaptive laboratory evolution, rational design, and random mutagenesis in anti-inhibitor research, and limited understanding of trade-offs between furfural tolerance and industrial fermentation robustness. Future efforts should address these gaps through combinatorial stress simulation, multi-omics profiling, and the “evolve–elucidate–engineer” paradigm, thereby enabling the scalable and stable application of lignocellulosic biomanufacturing. Full article

The mezcal industry in Mexico generates substantial volumes of vinasse, a waste product rich in organic material and bioactive compounds, yet its environmental impact and potential valorization in the food and biotechnological field remain underexplored. This study presents a comprehensive physicochemical and functional characterization of mezcal vinasse derived from mezcal production, including antioxidant activity and cytotoxicity assessment. Proximate analysis revealed high moisture content (96%) and a carbohydrate-rich profile (87.58% dry basis), with notable fiber fractions predominantly composed of insoluble dietary fiber (9.10% dry basis). Low-molecular-weight carbohydrate analysis identified fructose (60.46%) and glucose (10.48%) as the major components, and the hydrolyzed sample showed a monomeric profile with arabinose (31.98%) and glucose (24.14%) as the predominant sugars. Vinasse was found to provide antioxidant activity, as assessed by DPPH (296.3 µmol TE/g) and ABTS (465.3 µmol TE/g) colorimetric assays. Undesirable and antinutritional compounds such as tannins (15.3 mg catechin/g), oxalates (14.6 mg sodium oxalate/g), hydroxymethyl furfural (HMF) (3830.0 mg/L), and furfural (160.0 mg/L) were also quantified, highlighting potential environmental and nutritional concerns due to its mutagenic character at high concentrations. Despite these challenges, vinasse exhibited no cytotoxicity in Caco-2 cells at tested concentrations (25 to 100 mg/mL of phenolic extract), suggesting feasibility for further biotechnological applications. Full article

Pterospartum tridentatum (L.) Willk. (carqueja) is widely used in traditional medicine and culinary practices in the Iberian Peninsula; however, most studies have focused on its flowers, while its stems remain largely unexplored, despite representing a significant proportion of the plant biomass. This study aimed to evaluate the potential of P. tridentatum stems as a source of bioactive compounds using different extraction methodologies. Aqueous, hydroethanolic, ultrasound-assisted extraction (UAE) and pressurized liquid extraction (PLE) were applied, and the resulting extracts were characterized in terms of their extraction yield, protein and carbohydrate content, phenolic composition, antioxidant capacity, antimicrobial activity, and cytotoxicity in HaCaT and Caco-2 cell lines. Phenolic profiling by LC-ESI-QqTOF-HRMS tentatively identified 37 compounds, mainly corresponding to flavonoid and isoflavonoid glycosides, with genistein derivatives representing the dominant constituents across all extracts. Although extraction yields differed among methods, phenolic profiles were broadly similar. UAE and PLE extracts showed slightly higher antioxidant activity, while antimicrobial activity was limited, with only moderate inhibition observed against Staphylococcus epidermidis and Malassezia furfur. Additionally, cytotoxicity assays indicated low toxicity. Overall, the results demonstrate that P. tridentatum stems represent a promising yet underutilized biomass source of phenolic compounds with antioxidant potential and low cytotoxicity under the tested in vitro conditions. Full article

Pure LaFeO₃@C and LaCoO₃@C and substituted LaFe_1-xCo_xO₃ and LaCo_1-xFe_xO₃ perovskites (x = 0.10; 0.30) were used as catalysts for the liquid-phase oxidation of furfural at 150 °C and 30 bar of O₂ pressure. The perovskites were characterized by XRD, H₂-TPR, N₂ physisorption, TPR-MeOH, and XPS. The carbon in situ incorporation (@C) increases the surface area, favoring oxygen mobility leading to LaFeO₃@C stabilizing the redox pair Fe³⁺/Fe²⁺. In contrast, no evidence of the formation of a LaCoO₃@C perovskite structure through @C incorporation was observed. The gradual substitution of Fe with Co (10 and 30%) in LaFeO₃@C decreases the crystallinity, redox and basic properties, and surface area. For LaCoO₃@C, after the substitution of Co with 10 and 30% of Fe, only metal (La, Fe, Co) oxides as segregated phases were observed. The highest catalytic activity and selectivity to maleic acid of LaFeO₃@C is attributed to the higher surface area, crystalline structure, and surface-reducible Fe³⁺ species, favoring oxygen mobility and promoting their more oxidizing capacity. The lower catalytic activity of LaCoO₃@C, the Co- and Fe-substituted LaFeO₃@C and LaCoO₃@C catalysts, is attributed to the smaller surface area, and the similar selectivity towards maleic acid, 5-hydroxy-2(5H) and furanone indicates that the active site type is not modified in comparison to LaFeO₃@C. Full article

In response to the shortcomings still observed in polyethylene (PE)/ethylene-vinyl acetate (EVA)/styrene-butadiene-styrene (SBS) composite modified bitumen regarding storage stratification and low-temperature performance, this paper further introduces furfural extract, elemental sulphur, stabilisers and Z-6036 into this ternary system, and employs orthogonal design to screen the additive ratios. Tests were conducted on conventional physical properties, rotational viscosity, dynamic shear rheology and bending beam rheology, focusing on the material’s temperature sensitivity, rheological behaviour, low-temperature creep resistance and phase characteristics. The modification effects were analysed using fluorescence microscopy, scanning electron microscopy and infrared spectroscopy. Compared with the control group composed of 4% PE, 4% EVA and 2% SBS, the samples obtained from the orthogonal design showed an increase in elongation at 5 °C ranging from 52.5% to 213.9%; the difference in softening points decreased from 35.2 °C to a minimum of 0.1 °C, indicating improved storage stability. The temperature sensitivity of all sample groups was reduced, with the optimal group achieving a VTS of −0.4413, representing a 46.7% improvement over the control group. At −12 °C, the m-values of all nine orthogonal samples were higher than those of the control group, with seven groups reaching m ≥ 0.3, indicating improved low-temperature stress relaxation capability. A comprehensive analysis of the experimental results indicates that the selected chemical additives are beneficial for optimising the dispersion state and compatibility of the SBS/PE/EVA ternary modified bitumen, whilst also balancing rheological properties and low-temperature crack resistance to a certain extent. Microscopic and spectroscopic analyses further suggest that internal interactions within the system have been enhanced and the phase distribution has become more uniform; however, the current evidence is insufficient to conclusively determine that a specific form of chemical cross-linking reaction has occurred. Full article

The homogeneous nature of L-proline organocatalysts restricts their application in aldol condensation due to poor recyclability and stability. Herein, L-proline was heterogenized by ionic intercalation into Mg–Al layered double hydroxides (LDHs), yielding a series of proline-intercalated catalysts with tunable layer structures. Co-precipitation and memory-effect reconstruction strategies were employed to regulate interlayer spacing and proline loading. The resulting catalysts exhibited efficient performance in the aldol condensation of furfural with ketones under mild conditions. The reconstructed catalyst re-Mg₄Al₁P achieved a furfural conversion of 88.67% and a total product yield of 85.54% at room temperature, with product selectivity exceeding 95%. Structural characterizations confirmed that proline was stabilized within the LDH interlayers via R–COO—Mg electrostatic interaction while preserving the secondary amine active site. Mechanistic analysis indicated that the reaction proceeded through enamine- or enol-mediated pathways depending on water content, while the layered LDH framework imposed geometric confinement that suppressed side reactions. Catalyst deactivation in aqueous systems was mainly attributed to proline leaching rather than structural collapse. Full article

It is necessary to find sustainable alternatives to the conventional fossil fuels used by the transportation sector today. For the hard-to-abate aviation and heavy transport, liquid hydrocarbon fuels derived from biomass via pyrolysis are a viable option. Biomass pyrolysis oils need upgrading by hydroprocessing before they can be further processed into fuels at a refinery. Due to reactor plugging and catalyst deactivation in one-step hydroprocessing, it has been proposed to add a stabilization step at a lower temperature to convert the most reactive compounds in pyrolysis oil, such as carbonyls, to less reactive species such as alcohols. Three different catalysts, Ni/Al₂O₃, sulfided NiMo/Al₂O₃, and Pt/Al₂O₃, were studied for stabilizing three different model compounds, furfural, guaiacol, and octanoic acid, alone and as a mixture in a batch reactor at 90 bar initial H₂ pressure and 180 °C. The order of performance was determined to be Ni/Al₂O₃ > Pt/Al₂O₃ > sulfided NiMo/Al₂O₃ in these conditions. The Ni/Al₂O₃ catalyst showed both the highest overall conversion, the most fully hydrogenated compounds, and the highest carbonyl conversion. The effect of adding 1172 wt-ppm sulfur to the feed was also investigated, which showed that Ni/Al₂O₃ was the most sensitive catalyst to sulfur poisoning. Full article

5-Methoxymethyl-2-furfural (MMF) serves as a crucial biobased platform molecule that can be transformed into various high-value chemicals and biobased polyester monomers. However, the current production of MMF still faces several challenges, such as low yield and prolonged reaction time. In this study, we prepared a series of amide-modified strongly acidic resin catalysts and discovered that they have a higher efficiency in converting fructose to prepare MMF in 1-Butyl-3-methylimidazolium chloride ([BMIM]Cl) and methanol. Among the synthesized catalysts, DB757-NMP demonstrated superior performance, achieving an MMF yield of approximately 61.5% under the optimized conditions, with a combined yield of HMF and MMF reaching about 66.6%. The catalyst formation mechanism was analyzed using FTIR, and NMR, confirming the transformation of proton between NMP and the sulfonic acid groups of the resin, which collectively promoted the conversion of fructose to MMF. In addition, we investigated main reasons for catalyst deactivation and successfully restored catalytic activity through regeneration. The regenerated catalyst could be reused for three times with only a slight decrease in MMF yield. The results suggested that DB757-NMP is a more sufficient and recyclable catalyst for the production of MMF from fructose. This work presented a simple and environmentally benign approach for the synthesis of MMF. Full article

Thermal modification is widely applied to improve the durability and dimensional stability of wood; however, it alters the emission profile of volatile organic compounds (VOCs), which may affect indoor air quality. This study evaluated the effect of accelerated aging on VOC emissions from thermally modified Norway spruce (Picea abies) wood. Untreated and thermally treated samples (160, 180, and 210 °C) were subjected to accelerated aging in a xenon test chamber for 600 h. VOC emissions were analyzed using headspace gas chromatography–mass spectrometry (HS-GC-MS), and total VOC emissions (TVOC) were calculated from peak areas. Thermal modification significantly reduced TVOC compared to untreated wood, with samples treated at 210 °C showing up to a 376-fold decrease. Increasing modification temperature reduced the amount and variability of emitted VOCs and altered their chemical composition. Terpenes dominated in untreated wood, particularly α-pinene (51%), whereas thermally treated samples showed lower terpene content and higher proportions of carbonyl compounds such as furfural. Accelerated aging further affected VOC emissions, including a 42% decrease in TVOC for the 160 °C sample and compositional shifts characterized by the disappearance or formation of specific compounds. Thermal modification and subsequent aging substantially modify VOC emission profiles and improve emission stability of thermally treated spruce wood. Full article

Background: Pityriasis versicolor (PV) is a common superficial mycosis caused by Malassezia species. To describe the clinical and epidemiological characteristics of PV in Acapulco, Mexico, and to identify the associated Malassezia species using polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP). Methods: A cross-sectional study was conducted in 2024 at Acapulco General Hospital and a private dermatology clinic. Patients with clinically suspected PV and no recent antifungal or immunosuppressive treatment were enrolled. Skin scales were examined microscopically and cultured on modified Dixon agar. Isolates were identified using conventional methods and PCR-RFLP with HhaI and BstCI enzymes. Results: Sixty-nine patients were included; 68.1% were male, and the most affected age group was 11–20 years (34.8%). The hypochromic variant predominated (63.8%). PCR-RFLP identified M. globosa (33.3%) and M. furfur (31.9%) as the most frequent species, followed by M. restricta, M. sympodialis, and M. slooffiae. Species identification was unsuccessful in 11.6% of isolates. No statistically significant associations were found between clinical variants, gender, or species distribution. Conclusions: M. globosa and M. furfur were the predominant species in this tropical Mexican cohort. PCR-RFLP is a practical option for species-level identification, highlighting the diversity of Malassezia in PV. Full article