Search Results (90)

In order to address corrosion and pollution problems of liquid acids and limitations of traditional solid acids, sulfated MOF-808-SO₄ catalysts were developed by creating unsaturated sites in MOF-808 for sulfate grafting with ligand defect engineering. Characterization verified framework integrity, successful sulfate coordination, and maintenance of high surface areas and tunable porosity. Temperature-programmed desorption of ammonia (NH₃-TPD) establishes a clear consistent trend between defect density and the concentration as well as the strength of acid sites, indicating that a higher degree of ligand deficiency promotes the formation of more abundant and stronger acid centers. For esterification of acetic acid with n-butanol, the catalyst prepared by replacing 40 mol% of BTC with BDC achieved ≥99% conversion of acetic acid under mild conditions of 2.0 wt% catalyst loading and 1:2 alcohol/acid molar ratio at 120 °C for 6 h, outperforming conventional solid acids. This performance stems from high-density strong Brønsted acid sites strongly coordinated at defects and an open pore structure facilitating diffusion. The catalyst was easily recovered by ethanol washing and maintained stable activity over five cycles without loss of catalytic capability. This work suggests defect engineering as an effective strategy for tuning acidity and catalytic performance in MOF-based solid acids for green esterification. Full article

This article provides an overview of the physical pretreatments that can be applied to lignocellulosic biomass and their different benefits. It focuses on and compiles information on the main physical pretreatments applied to lignocellulose biomass, including the concept, advantages, disadvantages, and parameters of the pretreatments (milling, ultrasound, and microwave). A review of research carried out on different types of biomasses and what was obtained from them is also provided. Milling provides an essential mechanical change to optimize the surface, while microwave and ultrasonic methods provide sophisticated techniques that greatly increase the efficiency of transforming biomass through selective structural modification. The physical pretreatment goal is to improve the efficiency of conversion processes and increase the economic viability of using biomass as a renewable and sustainable source of energy and chemical products. The use of the energy of lignocellulosic biomass requires the proper implementation of pretreatments that facilitate the obtaining of biofuels and high-value biochemical products such as hemicellulose, lignin, and glucose derivatives, for example, ethanol, xylitol, butanol, and acetoacetic acid. Full article

2-Butanol is a promising biofuel due to its favorable properties and lower microbial toxicity compared to other butanol isomers. However, microbial production remains challenging due to the absence of a native biochemical pathway for directly converting sugars into 2-butanol. To achieve this goal, glucose should be directed through the 2,3-butanediol (2,3-BD) pathway, involving α-acetolactate synthase, α-acetolactate decarboxylase, and butanediol dehydrogenase for the formation of meso-2,3-BD, followed by diol dehydratase-catalyzed conversion of meso-2,3-BD to butanone and alcohol dehydrogenase-mediated reduction in butanone to 2-butanol. In this study, we report the development of six new recombinant strains based on Klebsiella pneumoniae G31, in which the metabolic pathway for converting glucose to meso-2,3-BD was extended to 2-butanol. All engineered strains harbored the vitamin B₁₂-dependent diol dehydratase complex (pduCDEGH) from Lentilactobacillus diolivorans DSM 14421 under its native promoter control. In addition, pduQ from the same strain, and adh from Clostridium beijerinckii DSM 51 encoding alcohol dehydrogenases were expressed under native, T7, or Ptac promoters. The highest yield of 2-butanol from glucose was achieved by K. pneumoniae K6 carrying the adh gene under the control of the T7 promoter—437 mg/L. Using 2-butanone as a substrate, K6 again produced the highest titer of 2-butanol (3.9 g/L), followed by the recombinant K8 (with adh under the Ptac promoter), and notably, by the native K. pneumoniae strains. Therefore, although pduQ encodes a key alcohol dehydrogenase in L. diolivorans, it has weaker properties than adh for the K. pneumoniae host in all promoter configurations. As the high expression levels of adh under T7 promoter control were driven by the native bacterial RNA polymerase, this promoter–host combination appears particularly suitable for developing other strains of industrial relevance. Full article

Real-time quaking-induced conversion (RT-QuIC) is highly sensitive for prion detection; however, inhibitory factors present in tissue homogenates readily interfere with the assay. We previously reported that recombinant cervid prion protein (rCerPrP) enabled the establishment of practical RT-QuIC for detecting chronic wasting disease and atypical bovine spongiform encephalopathy (BSE) prions, i.e., detecting low levels of prions in high concentration of brain tissue homogenates. Accordingly, the present study aimed to establish RT-QuIC for detecting classical BSE (C-BSE) and classical and atypical scrapie (C- and A-scrapie, respectively). A single-step lipid extraction using a 3:1 mixture of 2-butanol and methanol was effective as a pretreatment to remove inhibitors from brain homogenates. Among three rPrPs extensively evaluated, recombinant sheep PrP (rShPrP) was the most suitable substrate for practical detection of C-BSE prions. rCerPrP-173S/177N and rCerPrP-98S/173S/177N, which carry sheep-type amino acid substations at codons 173 and 177 and at codons 98, 173, and 177, showed excellent performance for detecting C-scrapie prions. Moreover, rCerPrP-98S/173S/177N, but not rCerPrP-173S/177N, was identified as an optimal substrate for detecting A-scrapie prions. These results suggested that combining inhibitor-removal pretreatment with the optimization of rPrP substrate for each animal prions further enhanced of RT-QuIC performance. Full article

Background/Objectives: [¹⁸F]Fluproxadine (formerly [¹⁸F]AF78) is a PET radiotracer targeting the norepinephrine transporter (NET) with potential applications in cardiac, neurological, and oncological imaging. Its guanidine moiety, while essential for NET binding, presents major radiosynthetic challenges due to high basicity and the harsh deprotection conditions required for protected precursors. Previous methods relied on multistep procedures, strong acids, and complex purification, limiting clinical translation. This study aimed to develop a practical one-step radiosynthesis suitable for routine and automated production. Methods: A direct SN2-type nucleophilic [¹⁸F]fluorination was performed using an unprotected guanidine precursor to eliminate deprotection steps. Reaction parameters, including the base system, solvent composition, precursor concentration, and temperature, were optimized under conventional and microwave heating. Radiochemical conversion (RCC) and operational robustness were evaluated, and purification strategies were assessed for automation compatibility. Results: Direct [¹⁸F]fluorination using the unprotected precursor reduced the total synthesis time to 60–70 min. Optimal conditions employed a tert-butanol/acetonitrile (4:1) solvent system with K₂CO₃/Kryptofix222, affording RCC up to 33% under conventional heating. Microwave irradiation further improved efficiency, achieving RCC of up to 64% within 1.5 min at 140 °C. The method showed broad tolerance to variations in the base molar ratio and precursor concentration and enabled isocratic HPLC purification. Conclusions: This one-step radiosynthesis overcomes longstanding challenges in [¹⁸F]fluproxadine production by eliminating harsh deprotection and enabling high-yield, automation-ready synthesis, thereby improving clinical feasibility. Full article

High-throughput colourimetric assays are widely used to screen phenolic phytonutrients in foods and plants, supporting discovery, quality control, and preliminary nutraceutical assessment. This review summarises the historical development, operating principles, and limitations of phenolic-based benchtop methods, and reports practical guidance for defensible application. The following colourimetric approaches are critically evaluated: Folin–Ciocalteu for total phenolics; AlCl₃-based and alternative total flavonoid methods; the pH-differential procedure for total monomeric anthocyanins; and tannin assays including vanillin–HCl, butanol–HCl (Porter), DMACA, protein-precipitation, and hydrolysable-tannin (rhodanine/ellagic-acid) protocols. For each method, common biases are identified, matrix interferences, reagent cross-reactivity, oxidative artefacts, dependence on calibration standard, and the chemical meaning of the readout is clarified. A best-practice framework is proposed: define the analytical target; pair complementary assays; pre-clean extracts; justify standards and wavelengths; control oxidation; validate spike-recovery and conversion checks; and contextualise outcomes using functional measures. A consistent conclusion emerges: no single method quantifies “total tannins” or “total flavonoids” across diverse matrices, and transparent reporting with method triangulation is essential for comparability and credible nutraceutical interpretation. The guidance consolidated here aims to standardise practice, minimise over- and underestimation artefacts, and strengthen the evidentiary value of data in food and nutraceutical research. Full article

With aging, harsh working conditions or sports injuries, the meniscus can degrade, causing pains to the patient. Nowadays, the treatment consists of the surgical replacement of this cartilage. Since this procedure can lead to complications due to open wounds and potential infections, synthesizing a polyurethane-based injectable joint filler represents an interesting alternative. In this study, poly(δ-decalactone)triol oligomers and Lysine diisocyanate were chosen as starting monomers to create an isocyanate-based prepolymer, because of their biocompatibility and liquid state at room temperature. Nevertheless, to fully replace the meniscus, the joint filler must crosslink in vivo, and this should occur in a short time window. Accordingly, in this work, we studied the catalytic activity of a range of relatively safe compounds for the alcohol/isocyanate addition reaction. A preliminary ¹H NMR kinetic study of the catalyzed addition of 1-butanol or 3-pentanol on lysine diisocyanate ethyl ester at body temperature has been performed to reach this objective. Among catalysts, stannous octoate was the most effective with either primary or secondary alcohol, allowing them to reach 92 and 80% alcohol conversion, respectively. In addition, the conversion of the primary and secondary isocyanates of lysine diisocyanate ethyl ester was monitored for all the catalysts and revealed different behaviors depending on the catalyst employed. Stannous octoate, unlike the others, showed a similar reactivity for primary and secondary isocyanates with conversions of 49 and 47%, respectively. Finally, when employing the most effective catalyst, curing of the poly(δ-decalactone) triisocyanate with glycerol at 35 °C provided a polyurethane elastomer that exhibits an elastic modulus of 519 kPa and a swelling index lower than 3% in PBS, making it suitable for injectable polyurethane joint filler application. Full article

Ethanol upgrading via catalytic C–C coupling, commonly known as the Guerbet reaction, offers a sustainable route to produce 1-butanol, a high-performance biofuel. To address gaps in the mechanistic understanding of the catalytic reaction, we investigated the process involving a fixed-bed reactor, operated at 275–325 °C, 21 bar, and weight hourly space velocities of 0.25–2.5 g_EtOH/(g_cat·h), using helium as a carrier gas, with a 5:1 He/EtOH molar ratio. The catalyst was a MgO–Al₂O₃ mixed oxide (Mg/Al = 2:1), derived from a hydrotalcite precursor. A detailed kinetic model was developed, encompassing 15 species and 27 reversible steps (10 sorption and 17 reaction steps), within a 1+1D sorption–reaction–transport framework. Four C₄-forming pathways were included: aldol condensation to form crotonaldehyde, semi-direct coupling to form butyraldehyde and crotyl alcohol, and direct coupling to form 1-butanol. To avoid overfitting, Arrhenius parameters were grouped by reaction type, resulting in sixty rate parameters and one active site-specific density parameter. The optimized model achieved high accuracy, with an average prediction error of 1.44 times the experimental standard deviation. The mechanistic analysis revealed aldol condensation as the dominant pathway below 335 °C, with semi-direct coupling to crotyl alcohol prevailing above 340 °C. The resulting model provides a robust framework for understanding and predicting complex reaction networks in ethanol upgrading systems. Full article

Poly(ε-caprolactone)-b-polysarcosine (PCL-b-PSar) block copolymers (BCPs) emerge as a promising alternative to conventional poly(ε-caprolactone)-b-poly(ethylene oxide) BCPs for biomedical applications, leveraging superior biocompatibility and biodegradability. In this study, we synthesized two series of PCL-b-PSar BCPs with controlled polymerization degrees (DP of PCL: 45/67; DP of PSar: 28–99) and low polydispersity indexes (Đ ≤ 1.1) and systematically investigated their crystallization-driven self-assembly (CDSA) in alcohol solvents (ethanol, n-butanol, and n-hexanol). It was found that the limited solubility of PSar in alcohols resulted in competition between micellization and crystallization during self-assembly of PCL-b-PSar, and thus coexistence of lamellae and spherical micelles. To overcome this morphological heterogeneity, we developed a modified self-seeding method by employing a two-step crystallization strategy (i.e., T_c1 = 33 °C and T_c2 = 8 °C), achieving conversion of micelles into crystals and yielding uniform self-assembled structures. PCL-b-PSar BCPs with short PSar blocks tended to form well-defined two-dimensional lamellar crystals, while those with long PSar blocks induced formation of hierarchical structures in the PCL₄₅ series and polymer aggregation on crystal surfaces in the PCL₆₇ series. Solvent quality notably influenced the self-assembly pathways of PCL₄₅-b-PSar₂₈. Lamellar crystals were formed in ethanol and n-butanol, but micrometer-scale dendritic aggregates were generated in n-hexanol, primarily due to a significant Hansen solubility parameter mismatch. This study elucidated the CDSA mechanism of PCL-b-PSar in alcohols, enabling precise structural control for biomedical applications. Full article

The sharp rise in the worldwide production of biodiesel has created an excess in the crude glycerol market, so it is essential to develop new added-value alternatives for crude glycerol. This paper describes a study on fermenting high concentrations of two types of medium-pure crude glycerol to solvents by Clostridium pasteurianum. The effect of media composition (iron, yeast extract, and vitamins) on solvents production was assessed by a full factorial design with pure glycerol. Granular activated carbon (GAC) adsorption was highly effective in removing impurities from crude glycerol. Following GAC pretreatment, fermentation of glycerol at initial concentration as high as 60 g L⁻¹ was possible, resulting in a butanol production of ~9 g L⁻¹. Based on these results, a batch fermentation with in situ gas stripping and pH controlled at ≥6.5 was shown to be the best alternative to enhance biomass growth, glycerol uptake, and solvent production. The combination of controlling pH in the early stages of fermentation with in situ butanol removal stabilised the metabolism of the strain and showed that the fermentation performance with crude glycerol is very similar to that of pure glycerol. With a notable uptake of glycerol (>83%), solvent production was >11 g L⁻¹ butanol (yield > 0.21 g g⁻¹_{glycerol consumed}) and >6 g L⁻¹ 1,3-propanediol (yield > 0.13 g g⁻¹_{glycerol consumed}). Setting the fermentation conditions to achieve a high uptake of high levels of glycerol with a similar product distribution is of great interest for the viability of the industrial processing of crude glycerol into chemicals via biological conversion. Full article

The aim of this work was to prepare a large set of variously substituted 3-aminophthalates starting from substituted 3-acylamino-2H-pyran-2-ones acting as dienes in Diels–Alder reactions with dialkyl acetylenedicarboxylates having the role of dienophiles. These thermally allowed [4+2] cycloadditions were taking place with normal electron demand due to rather electron-deficient dienophiles and relatively electron-rich dienes; however, they still required quite harsh reaction conditions: heating in closed vessels at 190 °C for up to 17 h was sufficient in most cases (albeit for a few reactions the time needed was up to 58 h) to achieve conversions above 95%. Such conditions, unfortunately, necessitated the use of a larger excess of dienophiles (as undesired polymerization takes place concomitantly); nevertheless, the straightforward isolation procedures enabled access to the target compounds in moderate to high yields (average yield 56%). All products were characterized by standard analytical and spectroscopic methods. With the goal of changing the reaction conditions to be more environmentally friendly, we investigated the effect of various solvents (water, n-butanol, butyl acetate, xylene, para-cymene, n-nonane, etc.) and the temperature applied (130–190 °C) on the conversion. We found that higher temperatures are necessary in most cases (except for the most reactive 2H-pyran-2-ones) regardless of the solvent used. Relative reactivity was determined for both sets of reactants and the experimentally obtained data show good agreement with the computational results. Full article

Several mixed oxides composed of Fe₃O₄, ZrO₂, and Al₂O₃ with different molar ratios were synthesized through a direct and simple mechanochemical approach. Subsequently, their physicochemical properties were investigated using a wide range of techniques, including TEM (transmission electron microscopy), XPS (X-ray photoelectron spectroscopy), XRD (X-ray diffraction), and N₂ adsorption/desorption, among others. These materials showed high surface areas and increased acidity compared to their respective counterparts. The catalytic activity of the synthesized materials was evaluated in the conversion of methyl levulinate (MEL) to γ-valerolactone (GVL) under microwave irradiation conditions, employing different alcohols as H-donor solvents (ethanol, 2-propanol, and 2-butanol). Due to their improved physicochemical properties originating from the ball-milling method, the as-synthesized materials (ZrFeOx 1:1, AlZrFeOx (5), and AlZrFeOx (10)) exhibited conversion rates of up to 99%, with complete selectivity for GVL after a relatively short reaction time of 30 min. Full article

The integration of perovskite with silicon for constructing tandem solar cells (TSCs) represents a promising route in photovoltaic technology. The hybrid sequential deposition (HSD) method, combining thermal evaporation and spin-coating, is crucial for developing perovskite films in textured perovskite/silicon tandem solar cells. However, the process faces challenges due to incomplete reactions caused by the dense perovskite coverage layer (CPCL) formed from high-crystallinity precursors. The CPCL hinders the diffusion of organic salts into the bottom precursor layer, leading to performance degradation and accelerated device aging. Herein, this study explores several polar solvents as additives to n-butanol (nBA) solvent in order to enhance the permeability of organic salts through the CPCL, and we demonstrate that dimethyl sulfoxide (DMSO) as an additive solvent can effectively assist organic salts in rapidly diffusing through the precursor layer, thereby promoting the complete transformation of uniform perovskite crystals. The resulting perovskite films exhibited complete conversion, uniform crystallization, and improved quality. As a result, the target TSCs achieved an increased maximum power conversion efficiency (PCE) of 29.12%. This study offers a robust pathway for depositing high-quality perovskite films on industrial-grade textured silicon substrates, laying a solid foundation for advancing perovskite/silicon tandem solar cells technology. Full article

The use of mixed cultures in gas fermentations could reduce operating costs in the production of liquid chemicals such as alcohols or carboxylic acids. However, directing reducing equivalents towards the desired products presents the challenge of co-existing competing pathways. In this study, two trickle bed reactors were operated at acetogenic and chain elongating conditions to explore the fate of electron equivalents (ethanol, H₂, and CO) and test pH oscillations as a strategy to target chain-elongated products. Hereby, the use of a H₂-rich syngas increased gas conversion rates and the specificity towards acetic acid (86% of C-mol production, 9.0 g L_EBV⁻¹ day⁻¹, with EBV referring to empty bed volume), while preliminary experiments with CO-rich syngas show promising results in increasing the ethanol production necessary to target chain-elongated products. On the other hand, ethanol supplementation hindered the endogenous ethanol production of the acetogenic culture but promoted butanol production (1.0 g L_EBV⁻¹ day⁻¹) at high ethanol concentrations (9.6 g L⁻¹) in the fresh media. Finally, pH oscillations improved chain elongation yields but negatively affected acetogenic growth, reducing production rates. Full article

Microreactors are essential for microchemical reactions owing to their high mass transfer efficiency, precise control of reaction time, easy amplification, and good safety performance. These characteristics provide several advantages, including shortened reaction times and enhanced chemical reaction conversion rates, rendering microreactors particularly significant in chemical production. In this study, a finite-rate model was developed for the esterification of monobutyl chlorophosphate (MCP) and n-butanol in a microchannel reactor. This study investigates the impact of the microchannel’s length-to-diameter ratio, the mass ratio of n-butanol to MCP at the inlet, and the inlet flow ratio on the entire reaction system through numerical simulations. The findings indicate that increasing the length-to-diameter ratio and reducing the inlet flow rate effectively prolongs the residence time of materials in the microreactor, thereby enhancing the conversion rate of the reactants. Optimal results are achieved with a moderate n-butanol/MCP mass ratio, which facilitates MCP transformation. Moreover, this study employs response surface analysis to investigate the influence of independent factors, such as the microchannel’s length-to-diameter ratio, component ratio, and inlet velocity ratio, on MCP conversion rates. A prediction formula with conversion rate as the dependent variable and microchannel length-to-diameter ratio, component ratio, and inlet velocity ratio as independent variables was established. Full article