ACS Omega最新文献

Thermochromic polymers have had significant developmentover theyears through consistent research. Specifically, polymers that involvean embedded ternary thermochromic compound, which consists of a dye,color developer, and cosolvent, have garnered a lot of attention forthe tunability of their color-changing properties. These compoundsexhibit color changes through the mechanism of proton transfer betweenthe dye and developer species, and the presence of a solvent is crucialto facilitating this phenomenon. By manipulating the type of eachcomponent within the dye-developer-solvent (DDS) compound, the color,direction of color change, and phase transition temperature can beadjusted. The fabrication of thermochromic polymers with DDS compoundscan be done through encapsulation, impregnation into a porous material,coating, or a combination of encapsulation and compounding with apolymer matrix. Potential applications of temperature-sensitive polymersinclude temperature sensors and heat regulators in packaging, clothing,medical devices, and architecture. Research efforts are being continuouslymade on DDS compounds to make them safer and more eco-friendly withthe replacement of conventional components with biobased materials.This review provides a comprehensive overview of the working principleof ternary thermochromic DDS compounds, the tunability of the thermochromicproperties, the current progress of research on utilizing DDS compoundsin polymers, and the prospects in developing nontoxic thermochromicpolymers for food packaging and medical applications.

Galvanization isone of the most common anticorrosive techniquesfor the protection of metallic structures in atmospheric applications.However, in extremely aggressive atmospheric environments, the materialfails to deliver its usual performance, and replacement can be necessary,as in this case study. Painted reinforced concrete has emerged asa promising alternative for extending the service life and enhancingcorrosion resistance. They combine the barrier and passivation mechanismsassociated with steel reinforcement embedded in concrete with theanticorrosive protection provided by the high-performance coatingsystems. In this context, this work evaluated the performance of combinationsof carbon steel and galvanized steel reinforcement concrete with threecommercial coating systems (CS1, CS2, and CS3) under severe conditionsexpected at the installation site. The test specimens were manufacturedusing Brazilian CPII cement concrete, and the performance of galvanizedsteel was assessed in comparison to the expected behavior of carbonsteel. Concrete characterization tests were conducted to verify itssuitability for the intended application, including water absorption,void index, bulk density, and compressive strength tests, and saltspray exposure tests were performed to assess the anticorrosive performanceof the different combinations. Each coating system was individuallycharacterized using techniques to measure its physical and barrierproperties, and the reinforcing steels were evaluated for their mechanicalproperties and chemical compositions. Electrochemical methods, includingopen-circuit potential monitoring, electrochemical impedance spectroscopy,and polarization resistance, were used to complement the other analyses.The results indicated that the traditional carbon-steel-and-concretesystem exhibited a superior anticorrosive performance. Even afterlong-term exposure to salt spray, the specific influence of each coatingsystem applied to the concrete could not be clearly distinguished,given its excellent anticorrosive performance. Despite this, CS3 consistentlyshowed favorable results in the characterization tests and was thereforeselected for the final application.

Methane/air mixturesin preheated and pressurized processequipmentmay exhibit a broadened flammability envelope, which is critical forexplosion-hazard assessment and safety-envelope definition. Reliableupper flammability limit (UFL) data under elevated-temperature andelevated-pressure conditions are therefore needed for methane-relatedindustrial systems. In this work, the UFLs of methane/air mixtureswere measured in a 20 L closed spherical vessel at initial temperaturesof 25–100 °C and pressures of 0.1–1.0 MPa in accordancewith EN 17624:2022 and GB/T 42368–2023. Within the investigatedrange, the UFL increases approximately linearly with temperature andlogarithmically with pressure. Under simultaneous temperature andpressure elevation, the increase in UFL is greater than that estimatedfrom the simple superposition of their individual effects, indicatinga non-negligible interaction between the two parameters. Based onthe full experimental matrix, an empirical correlation incorporatinga temperature–pressure interaction term is proposed to representthe UFL surface and shows good agreement with the experimental data.Chemical-kinetic simulations using USC Mech II were performed to assistinterpretation of the experimental trends. The normalized sensitivityanalysis identifies temperature-promoted branching pathways and pressure-enhancedradical stabilization/recombination pathways as the principal competingkinetic tendencies near the UFL. The present work provides a protocol-compliantmethane/air UFL data set and a practical correlation for preheatedand pressurized methane systems.

RNA size markersare essential for denaturing Urea-PAGE analysis,but commercial RNA ladders are expensive, available only in fixedsize ranges, and require careful handling to prevent RNA degradation.Here, we developed a modular dual-ribozyme platform for preparingRNA size standards from single T7 transcription templates. Each constructcontains a central RNA segment flanked by hammerhead and HDV ribozymes,enabling cotranscriptional self-cleavage to generate a predictableset of RNA products. The SYSU25 construct reproducibly produced shortRNA marker bands at 25, 50, and 75 nt, whereas the SYSU100 constructgenerated six products ranging from 100 to 600 nt. The experimentallyobserved ladder patterns were reproducible using either an in-houseor commercial T7 transcription system. A 500 μL in-house transcriptionpreparation of either SYSU25 or SYSU100 provided sufficient materialfor approximately 50 analytical gel lanes. We further prepared syntheticssDNA marker sets (S6D and M4D) and calibrated the S6D ladder againstRNA standards of known length on 10%, 12%, 15%, and 20% Urea-PAGEgels. This calibration demonstrated that ssDNA and RNA do not migratesolely according to nucleotide length and provided gel-dependent RNA-equivalentsize assignments for the S6D bands within the calibrated range. Together,the dual-ribozyme RNA ladders and RNA-calibrated ssDNA markers providea low-cost reference system for the analysis of short- to medium-lengthRNA.

Drug repurposinghas led to the identification of tamoxifen, awell-known chemotherapy drug, as a compound with relevant antibacterialproperties. In this field, the development of new tamoxifen derivativeswith antimicrobial activity, particularly against colistin-resistant Acinetobacter baumannii, represents an importantarea of research. We evaluated the MICs of 22 and 3 tamoxifen derivativesagainst wild-type and colistin-resistant A. baumannii strains, respectively, using microdilution assays, either as monotherapyor in combination with colistin. While all derivatives showed MICvalues above 64 mg/L when tested as monotherapy, combining derivatives 1, 14, and 18 with colistin reducedtamoxifen derivatives’ MICs to 0.125–2 mg/L for thereference strain ATCC 17978 and to 0.5–1 mg/L for the colistin-resistantAb22 strain. Growth assays showed that these derivatives delayed Ab22proliferation during the first 4 h. Moreover, these derivatives increasedmembrane permeabilization without altering the expression of the outermembrane proteins (OMPs). These findings suggest that tamoxifen derivativesin combination with colistin exhibit antibacterial activity againsta colistin-resistant A. baumannii, potentially broadeningthe spectrum of available drug treatments for combating MDR A. baumannii.

SRP54, a key component of the signal recognition particle,is ahighly conserved enzyme both structurally and functionally. The proteinplays a vital role in cellular protein translocation by interactingwith the translating ribosome and a membrane receptor, thereby aidingprotein folding and trafficking. Recent studies have shown that mutationsin the SRP54 gene cause severe neutropenia and areassociated with an increased risk of pediatric leukemias. Here, wepresent high-resolution structures of clinically relevant SRP54 mutantproteins from the archaea Pyrococcus furiosus. This work complements existing structural and functional data onSRP54 and offers a high-resolution structural basis for clinicallyrelevant congenital mutations. The structures of three mutants arepresented along with the model wild type. Overall, the results providea detailed understanding of how mutations affect SRP54 structure.Additionally, comparing our findings with available structures fromhigher eukaryotes offers new insights into the mechanisms of dysfunction.

Multitarget ligandsderived from established cholinesterase inhibitorsoffer a strategy for addressing the multifactorial pathology of Alzheimer’sdisease, but biological potency must be considered together with developability.In this study, a rapid biomimetic high-performance liquid chromatography-basedworkflow was used to characterize key absorption, distribution, metabolismand excretion-related properties of 26 donepezil- and rivastigmine-derivedhybrid compounds, including plasma stability, plasma protein binding,membrane affinity, biomimetic distribution parameters, blood–brainbarrier permeability, intestinal absorption, experimental log P and aqueous solubility. Plasma stability was reassessedusing first-order regression across seven time points with 95% confidenceintervals. Most profiles showed limited degradation during the 24h experiment; accordingly, many apparent half-lives required extrapolationand are interpreted as comparative stability parameters rather thanestimates of in vivo persistence. Human serum albuminand α1-acid glycoprotein binding was generally high, emphasizingthe need to balance protein binding with the unbound fraction, whileimmobilized artificial membrane-based models predicted central nervoussystem-positive classification and high intestinal absorption acrossthe series. Importantly, the blood brain barrier permeability andCNS-distribution estimates are derived from biomimetic models andshould be regarded as predictive descriptors that require confirmationin dedicated in vivo pharmacokinetic studies. Solubilitywas more variable and emerged as an important differentiating property,with compound (26) showing the most favorable profile.An exploratory desirability-based ADME score placed compounds (15), (8), (26), (4),(10) and (24) in the highest tier. Integrationwith previously reported cholinesterase, fatty acid amide hydrolaseand monoamine oxidase activities, which were not remeasured in thepresent study, further refined lead selection: (24) providedthe clearest potency-developability compromise and was prioritizedas the principal lead, whereas (26) emerged as a developability-orientedcolead. (3) and (18) remained potency-drivensecondary candidates. Overall, combining biomimetic ADME profilingwith existing pharmacological evidence provides a transparent frameworkfor early lead prioritization and supports confirmatory pharmacokinetic,exposure and in vivo efficacy studies.

The COVID-19 pandemic profoundly affected global publichealth.Intensive efforts have led to the development of vaccines and antiviraldrugs. However, the emergence of SARS-CoV-2 variants has raised concernsabout resistance to therapies, making the exploration of alternativemolecular pathways a promising strategy. Cathepsins stand out in thiscontext due to their crucial role in mediating SARS-CoV-2 entry viaendosomes. Structurally, these enzymes share high similarity withproteases from other organisms such as Leishmania CPB. Previously, we reported the synthesis and activity of 17 flavonoidderivatives as CPB inhibitors with robust antimicrobial activity.Motivated by the high resemblance between the active sites of CPBand CatB, we evaluated the anti-SARS-CoV-2 activity of these compoundsand validated cathepsins as their main molecular target. Among them,nine flavonoid derivatives exhibited potent simple-linear noncompetitivedual CatB/CatL inhibition, with K_i valuesranging from 3.20 to 29.05 μM for CatB and from 2.41 to 12.44μM for CatL. Chalcones 1c, 2a, and 2b translated this enzymatic activity into significant reductionsin SARS-CoV-2 titers (IC₅₀ = 12.06, 1.05, and 2.12 μM,respectively), while demonstrating low toxicity in both Vero-CCL81and L929 cells. Their potential direct effects on viral replicationwere also evaluated using SARS-CoV-2 main protease assays and virucidaltests. No compound showed activity on viral targets, suggesting thatcathepsin inhibition is their potential antiviral mechanism. Althoughadditional mechanistic assays are still required, these data provideinitial support for the involvement of dual CatB/CatL as antiviraltargets and offer insights for the development of chalcone-based leadsagainst COVID-19.

Lignocellulosic hydrolysatesderived from hydrothermalprocessingoften result in low ethanol yields, which are commonly attributedto inhibitory compounds and suboptimal sugar composition. However,the relative contribution of sugar availability and microbial metabolicefficiency to these limitations remains poorly understood. This studysystematically evaluated the ethanol production by Scheffersomyces stipitis using hydrolysates obtainedfrom steam explosion (SE), subcritical water hydrolysis (SWH), enzymatichydrolysis (EH), and their sequential combinations, under identicalfermentation conditions. To decouple process limitations, ethanolyields were analyzed based on both total sugar available and sugareffectively consumed. Results showed that hydrothermal hydrolysates(SE and SWH) led to low ethanol yields (0.08–0.14 g/g), primarilydue to limited sugar uptake associated with the presence of inhibitorycompounds and low sugar concentrations. In contrast, enzymatic hydrolysates,particularly after SE pretreatment (SE + EH), achieved yields up to0.50 g/g, approaching the theoretical maximum. Notably, when yieldswere calculated based on sugar consumed, significantly higher efficiencieswere observed across all conditions, revealing that the intrinsicmetabolic capacity of S. stipitis remainedlargely preserved even in inhibitory media. These findings demonstratethat reduced ethanol production in lignocellulosic hydrolysates ispredominantly governed by limitations in sugar assimilation ratherthan metabolic conversion. This study provides a mechanistic frameworkfor distinguishing between substrate accessibility and metabolic efficiency,offering new insights for the optimization of second-generation ethanolprocesses.

An antibacterial metabolite was isolated from the endophyticfungus Fusarium incarnatum JMB4 associatedwith Jatropha multifida L. by bioactivity-guidedchromatographyand recrystallization. The isolated compound was assigned as equisetinusing UV–vis, FTIR, LC–MS/MS, and ¹H NMRdata. Anti-MRSA activity was evaluated by disk diffusion, with chloramphenicoland amoxicillin as antibiotic comparators. At 1% (w/v; 100 μg/disk),equisetin produced an inhibition zone of 23.94 ± 0.66 mm; therecorded comparator zones were 24.71 ± 0.68 mm for chloramphenicol(30 μg/disk) and 11.76 ± 0.66 mm for amoxicillin (25 μg/disk).The lowest tested equisetin concentration producing a measurable zonewas 78.1 μg/mL (7.03 ± 0.25 mm). This diffusion end pointdoes not represent a minimum inhibitory concentration (MIC), and theunequal disk loads preclude a direct comparison of intrinsic antibacterialpotency. Exploratory docking against penicillin-binding protein 2a(PBP2a) yielded a score of −5.5041 kcal/mol and a predictedpose outside the canonical catalytic pocket. A 100 ns molecular dynamicssimulation described the behavior of the modeled complex but did notestablish PBP2a inhibition. These results document anti-MRSA activityof the isolated compound under the tested conditions; standardizedMIC determination and further structural validation remain necessary.