Acid Sites Research Articles

Enhancing Water Tolerance and N2 Selectivity in NH3-SCR Catalysts by Protecting Mn Oxide Nanoparticles in a Silicalite-1 Layer.

Mn-based catalysts are promising candidates for eliminating harmful nitrogen oxides (NOx) via selective catalytic reduction with ammonia (NH3-SCR) due to their inherent strong redox abilities. However, poor water tolerance and low N2 selectivity are still the main limitations for practical applications. Herein, we succeeded in preparing an active catalyst for NH3-SCR with improved water tolerance and N2 selectivity based on protecting MnOx with a secondary growth of a hydrophobic silicalite-1. This protection suppressed catalyst deactivation by water adsorption. Interestingly, impregnating MnOx on MesoTS-1 followed by silicalite-1 protection allowed for a higher dispersion of MnOx species, thus increasing the concentration of acid sites. Consequently, the level of N2O formation is decreased. These improvements resulted in a broader operating temperature of NOx conversion and a modification of the NH3-SCR mechanism. Diffuse reflectance infrared Fourier transform spectroscopy analysis revealed that unprotected Mn/MesoTS-1 mainly followed the Eley-Rideal mechanism, while Mn/MesoTS-1@S1 followed both Langmuir-Hinshelwood and Eley-Rideal mechanisms.

Molecular Evolutionary Dynamics of Coxsackievirus A6 Causing Hand, Foot, and Mouth Disease From 2021 to 2023 in China: Genomic Epidemiology Study.

Hand, foot, and mouth disease (HFMD) is a global public health concern, notably within the Asia-Pacific region. Recently, the primary pathogen causing HFMD outbreaks across numerous countries, including China, is coxsackievirus (CV) A6, one of the most prevalent enteroviruses in the world. It is a new variant that has undergone genetic recombination and evolution, which might not only induce modifications in the clinical manifestations of HFMD but also heighten its pathogenicity because of nucleotide mutation accumulation. The study assessed the epidemiological characteristics of HFMD in China and characterized the molecular epidemiology of the major pathogen (CV-A6) causing HFMD. We attempted to establish the association between disease progression and viral genetic evolution through a molecular epidemiological study. Surveillance data from the Chinese Center for Disease Control and Prevention from 2021 to 2023 were used to analyze the epidemiological seasons and peaks of HFMD in Henan, China, and capture the results of HFMD pathogen typing. We analyzed the evolutionary characteristics of all full-length CV-A6 sequences in the NCBI database and the isolated sequences in Henan. To characterize the molecular evolution of CV-A6, time-scaled tree and historical population dynamics regarding CV-A6 sequences were estimated. Additionally, we analyzed the isolated strains for mutated or missing amino acid sites compared to the prototype CV-A6 strain. The 2021-2023 epidemic seasons for HFMD in Henan usually lasted from June to August, with peaks around June and July. The monthly case reporting rate during the peak period ranged from 20.7% (4854/23,440) to 35% (12,135/34,706) of the total annual number of cases. Analysis of the pathogen composition of 2850 laboratory-confirmed cases identified 8 enterovirus serotypes, among which CV-A6 accounted for the highest proportion (652/2850, 22.88%). CV-A6 emerged as the major pathogen for HFMD in 2022 (203/732, 27.73%) and 2023 (262/708, 37.01%). We analyzed all CV-A6 full-length sequences in the NCBI database and the evolutionary features of viruses isolated in Henan. In China, the D3 subtype gradually appeared from 2011, and by 2019, all CV-A6 virus strains belonged to the D3 subtype. The VP1 sequences analyzed in Henan showed that its subtypes were consistent with the national subtypes. Furthermore, we analyzed the molecular evolutionary features of CV-A6 using Bayesian phylogeny and found that the most recent common ancestor of CV-A6 D3 dates back to 2006 in China, earlier than the 2011 HFMD outbreak. Moreover, the strains isolated in 2023 had mutations at several amino acid sites compared to the original strain. The CV-A6 virus may have been introduced and circulating covertly within China prior to the large-scale HFMD outbreak. Our laboratory testing data confirmed the fluctuation and periodic patterns of CV-A6 prevalence. Our study provides valuable insights into understanding the evolutionary dynamics of CV-A6.

Challenging design of highly active Pt/CeO2–TiO2/ZSM-5 catalysts for VOCs low-temperature removal

Four Pt/CeO2–TiO2/ZSM-5 catalysts with different Pt species dispersion states and acidic properties were designed, and key factors affecting the oxidation activity of various VOCs (benzene, DCE, ethyl acetate and acetonitrile as typical organic compounds of aromatic hydrocarbon and halogen/oxygen/nitrogen-containing VOCs, respectively) were identified in the present work. The strength of the acid and oxidation sites on the surface of catalysts and their synergistic interaction play a crucial role. Highly dispersed Pt species and its strong redox ability promote low-temperature oxidation of benzene. A synergistic interaction between the acid and oxidation sites is required to achieve high DCE oxidation activity. An abundance of surface acid sites (particularly strong acid sites) favors the adsorption and dechlorination to form vinyl chloride of DCE, and the strong redox ability of oxidation sites would accelerate the deep oxidation of intermediates (such as vinyl chloride and acetic acid, etc.). For ethyl acetate or acetonitrile oxidation, the strong acidic property of the catalyst plays a prior role for their catalytic oxidation, which facilitates the low-temperature hydrolysis of ethyl acetate or acetonitrile. This work provides a significant thought to design and synthesize high activity catalysts for low-temperature oxidation of various VOCs pollutants.

Synthesis of Co/Ni-Doped mesoporous spinel ferrite microspheres for enhanced Low-Temperature SCR performance

The iron-based catalysts commonly used in the selective catalytic reduction (SCR) process cannot meet the increasingly stringent low-temperature NOx emission targets. In this study, mesoporous microspherical MFe2O4 (M=Co, Ni) spinel ferrite catalysts were synthesized by hydrothermal method and applied to the SCR of ammonia (NH3-SCR) reaction. Compared to Fe3O4, both NiFe2O4 and CoFe2O4 catalysts showed higher SCR catalytic activity at low temperature. The NiFe2O4 catalyst achieved a NO conversion of 95.5 % at 240 °C, while CoFe2O4 exhibited a high NO conversion of 97.6 % at 180 °C and a N2 selectivity of 99.6 %. Various characterization experiments revealed that the introduction of Co and Ni resulted in the formation of a specific mesoporous microsphere morphology in CoFe2O4 and NiFe2O4 catalysts, along with the generation of a large number of oxygen vacancies and acidic sites on the surface. These features facilitate the sequential adsorption and activation of NH3 and NOx species, resulting in excellent catalytic activity at low temperatures. Detailed in situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) measurements showed that on NiFe2O4 the reaction follows the Eley–Rideal (E–R) mechanism, whereas it proceeds through the Langmuir–Hinshelwood (L–H) and Eley–Rideal (E–R) mechanisms on the CoFe2O4 catalyst. This work provides a feasible strategy for enhancing the low-temperature SCR reaction over iron-based catalysts; moreover, the elucidation of the complete reaction mechanism offers a solid foundation for future improvements in denitrification catalysts.

Frustrated Lewis pairs on hollow flower-liked carbon nitride by phosphorous and tungsten co-doping to enhance photocatalytic performance

Frustrated Lewis pairs (FLPs) exhibit a distinctive “push-pull” effect that efficiently triggers the activation of diverse molecules, leading to unforeseen catalytic capabilities. In this study, phosphotungstic acid (PTA) is introduced into graphitic carbon nitride (g-C3N4). Here, phosphorus (P) as the Lewis acid (LA) site, while the electron-rich N-active site neighboring tungsten (W) assumes the role of the Lewis base (LB) site, giving g-C3N4 a FLPs-like property. The formation of FLPs creates a robust “pull-push” effect, thereby improving the separation of photogenerated carriers. This prepared CNW-20 sample demonstrates effective photocatalytic capabilities for hydrogen (H2) evolution and for degrading organic pollutants. Production levels of H2 reached up to 1044.36 μmol h−1·g−1, surpassing the bulk g-C3N4 by a factor of 14. Concurrently, the efficiency of CNW-20 sample in degrading tetracycline hydrochloride (TC) reached 83.40 %. This study introduces a novel approach for the systematic design of FLP sites on metal-doped photocatalysts, aiming to enhance the efficiency of H2 generation and the degradation of pollutants.

Molecular Modification Enhances Xylose Uptake by the Sugar Transporter KM_SUT5 of Kluyveromyces marxianus.

This research cloned and expressed the sugar transporter gene KM_SUT5 from Kluyveromyces marxianus GX-UN120, which displayed remarkable sugar transportation capabilities, including pentose sugars. To investigate the impact of point mutations on xylose transport capacity, we selected four sites, predicted the suitable amino acid sites by molecular docking, and altered their codons to construct the corresponding mutants, Q74D, Y195K, S460H, and Q464F, respectively. Furthermore, we conducted site-directed truncation on six sites of KM_SUT5p. The molecular modification resulted in significant changes in mutant growth and the D-xylose transport rate. Specifically, the S460H mutant exhibited a higher growth rate and demonstrated excellent performance across 20 g L-1 xylose, achieving the highest xylose accumulation under xylose conditions (49.94 μmol h-1 gDCW-1, DCW mean dry cell weight). Notably, mutant delA554-, in which the transporter protein SUT5 is truncated at position delA554-, significantly increased growth rates in both D-xylose and D-glucose substrates. These findings offer valuable insights into potential modifications of other sugar transporters and contribute to a deeper understanding of the C-terminal function of sugar transporters.

Synergistic catalysis of NO and chlorobenzene over Mn3O4-CeO2 catalysts: Acid sites, catalytic pathway and mechanism

Catalyst active sites and surface acidity are crucial for the synergistic catalysis of NOx and dioxins, determining the selectivity towards N2 and CO2. This study synthesized Mn3O4-CeO2 catalysts to investigate the influence of these sites on the catalytic performance for NO and chlorobenzene. Mn0.086Ce, made by the redox method, showed the highest Mn-Ce interface, achieving nearly complete conversion of chlorobenzene and NO at 180℃, with CO2 and N2 selectivity reaching about 80 % and 100 %, respectively. EPR, NH3-TPD and Py-IR analyses revealed that the Mn-Ce interface induces the formation of Lewis acid sites and oxygen vacancies, facilitating the adsorption and conversion of chlorobenzene, NH3, and NO. Mn adjacent to Lewis acid sites is the main active site, while Ce acts as an electron transfer agent. Based on the results of in-situ DRIFTS and TOF-SIMS, the possible degradation pathway for chlorobenzene was proposed and as follows: phenol, benzoquinone, maleic anhydride, propionic acid, CO2, and H2O. The NH3-SCR reaction follows the Eley-Rideal mechanism at 150–300℃.

Whole-exome Sequence Analysis of Gastric-type Adenocarcinoma of the Uterine Cervix and Adjacent Lobular Endocervical Glandular Hyperplasia in the Same Case.

Lobular endocervical glandular hyperplasia (LEGH) may be a precursor lesion of gastric-type adenocarcinoma of the uterine cervix (GAS). However, the genetic mechanisms underlying its carcinogenesis remain unclear. To elucidate the oncogenic process from LEGH to GAS, we compared gene mutations in early-stage GAS and adjacent LEGH in the same case. Fresh-frozen tissue sections were obtained from a patient with Stage IB3 GAS and adjacent LEGH who had undergone hysterectomy. Using laser microdissection, we harvested the LEGH and GAS portions separately from these sections and extracted the genomic DNA. Somatic variant analysis using whole-exome sequencing used DNA from the normal myometrium as a reference sequence. Somatic variants involving amino acid substitutions were detected in 61 and 125 locations in LEGH and GAS, respectively. Seven variants were common in both lesions, of which the pathogenic variant was GNAS only (c.2531G>A, p.R844H), a mutation frequently reported in pancreatic and colorectal cancers. LEGH had no other pathogenic variants; another pathogenic variant in GAS was found only at the same amino acid site as GNAS (c.2530C>T, p.R844C). In the present case, LEGH and GAS shared the same pathogenic variant of GNAS, indicating that both lesions had a common origin. Furthermore, the current results showed that the second GNAS variant is associated with the progression of LEGH to GAS. Further studies are required to elucidate GAS's pathogenesis and biological characteristics.

Ketalization mechanism of glycerol to biobased glycerol levulinate ketal over HZSM-5: A combined experimental and theoretical study

Methyl levulinate ketal (MLK) is a novel biobased chemical derived from glycerol via ketalization, and exploring its synthesis mechanism is of great significance for the high-value utilization of biomass resources. In this study, the ketalization reaction of glycerol was evaluated using the MLK yield calculated by the GC internal standard method. The acidity of HZSM-5 was determined by NH3-TPD. The catalyst screening experiments demonstrated that HZSM-5 in zeolites and AlCl3 in metal salts exhibited high catalytic activity in the synthesis of MLK. Furthermore, the kinetic results indicated that the HZSM-5 zeolite catalyst exhibited a lower apparent activation energy in catalyzing the synthesis of MLK compared to the metal salt catalyst AlCl3. The ketalization reactions of levulinate and glycerol catalyzed by different types of acidic sites in HZSM-5 were then investigated using the density functional theory method. A comprehensive catalytic path, free energy changes, intermediates, and transition state structures were proposed. Furthermore, the free energy barriers of ethyl levulinate ketal and butyl levulinate ketal catalyzed by HZSM-5 were calculated, and the difference between the steric hindrance effect and the electronic effect of alkyl in levulinate was compared. This study enhances the understanding of ketalization reactions and will be useful in future catalyst design studies.

Tandem catalytic conversion of glucose and cellobiose to 5-ethoxymethylfurfural with record yields

The conversion of biomass-derived carbohydrates to 5-ethoxymethylfurfural (EMF) is a fascinating reaction with 100% carbon atom utilization. Although effective conversion of 5-hydroxymethylfurfural (HMF) and fructose to EMF have been achieved, the direct conversion of glucose only gave low EMF yields. Herein, we reveal that the combinations of common Lewis acid with Brønsted acid in ethanol universally catalyze rapid etherification of glucose to intractable ethyl glucoside (EGL), as impedes the further conversion toward the desired products. The synergy of large-pore tin phosphate (SnPO) bearing strong Lewis acidic sites with acidic ionic liquid 1-(4-sulfobutyl)-3-methylimidazolium chloride (BSO3HMIMCl) enable tandem catalytic conversion of glucose, cellobiose and starch to EMF with record yields (61.7%, 61.8% and 55.7%, respectively), far exceeding previous reports. This transformation probably occurs via multiple parallel pathways, where water molecules generated by dehydration cooperate with acid and Cl- to hydrolyze EGL back to glucose, thus forming a positive feedback on EMF production.

Mechanistic investigation of methanol-to-olefins conversion catalyzed by H-ZSM-5 zeolite: a DFT study.

The mechanisms for the formation of the first C - C bond and lower olefins on methanol to olefins (MTO) conversion on H-ZSM-5 had been focused in dispute. In this paper, density functional theory has been used to study the reaction mechanisms of methanol to olefins on ZSM-5. The configurations of reactants, intermediates, products and transition state of the numerous reactions involved in such a process have been optimized, as well as the elementary reactions related to these configurations were determined by the calculation of corresponding activation energy barriers and reaction heats. Here, two different kinds of the mechanisms were proposed for the formation of dimethylether (DME), one involving an associative interaction of two methanol molecules with the zeolite Brønsted acid sites and the other occurring via a surface methoxy species and a methanol molecule. A critical intermediate of the methoxy methyl cation was theoretically verified by the reaction of the methoxy species and dimethylether. Besides, it was found that the first intermediates containing a C - C bond were 1,2-dimethoxyethane and 2-methoxy-ethanolare, in which the former was formed from methoxy species with dimethyl ether and the latter was formed from methanol by onium ions((CH3)2O+CH2CH2OCH3), respectively. For the whole reaction mechanism, the results in this paper indicated that the ethene formation is more favorable than propylene formation due to the low activation energy barrier for ethene formation (123.49 vs. 162.09kJ.mol-1). From these calculations, it would be concluded that ethene is the first alkene product that induces the occurrence of the hydrocarbon pool mechanism. All the periodic density function theory (DFT) calculations were performed by the Vienna Ab Initio Simulation package (VASP). The interaction between nucleus and valence electron was described using the pseudopotentials found in the projector augmented wave (PAW) method. PBE-D3 was used in the whole DFT calculations and CI-NEB was used to locate transition state.

Genomic and Transcriptomic Insights into the Evolution of C4 Photosynthesis in Grasses.

C4 photosynthesis has independently evolved over 62 times within 19 angiosperm families. The recurrent evolution of C4 photosynthesis appears to contradict the complex anatomical and biochemical modifications required for the transition from C3 to C4 photosynthesis. In this study, we conducted an integrated analysis of genomics and transcriptomics to elucidate the molecular underpinnings of convergent C4 evolution in the grass family. Our genome-wide exploration of C4-related gene families suggests that the expansion of these gene families may have played an important role in facilitating C4 evolution in the grass family. A phylogenomic synteny network analysis uncovered the emergence of C4 genes in various C4 grass lineages from a common ancestral gene pool. Moreover, through a comparison between non-C4 and C4 PEPCs, we pinpointed 14 amino acid sites exhibiting parallel adaptations. These adaptations, occurring post the BEP-PACMAD divergence, shed light on why all C4 origins in grasses are confined to the PACMAD clade. Furthermore, our study revealed that the ancestor of Chloridoideae grasses possessed a more favorable molecular preadaptation for C4 functions compared to the ancestor of Panicoideae grasses. This molecular preadaptation potentially explains why C4 photosynthesis evolved earlier in Chloridoideae than in Panicoideae and why the C3-to-C4 transition occurred once in Chloridoideae but multiple times in Panicoideae. Additionally, we found that C4 genes share similar cis-elements across independent C4 lineages. Notably, NAD-ME subtype grasses may have retained the ancestral regulatory machinery of the C4 NADP-ME gene, while NADP-ME subtype grasses might have undergone unique cis-element modifications.

Silicate minerals enable the efficient photocatalytic RWGS reaction

Silicate minerals are the most abundant minerals on Earth’s crust and can originate from rock-forming minerals with the low risk to the environment. Herein, the chain pyroxene mineral NaFeSi2O6 nanosheets loaded with highly dispersed Cu nanoparticles have been used as an archetype platform for the efficient photocatalytic reverse water gas shift (RWGS) reaction. The resultant Cu/NaFeSi2O6 catalyst demonstrated high performance metrics in the gas-phase photocatalytic hydrogenation of CO2 to CO, with a yield as high as 13144 μmol gcat–1 h–1. It is shown that the coordinately unsaturated Fe atom in NaFeSi2O6 can serve as a robust Lewis acid site for adsorbing and activating CO2 molecules, while the metal/support interface facilitates the formation of intermediate species and the subsequent production of CO products through hydrogen spillover. The surface plasmon resonance (SPR) effect of Cu further promotes the injection of hot electrons into NaFeSi2O6 and the carrier separation and migration at the Schottky heterojunction. This low-cost and earth-abundant mineral-based catalyst exhibits 100 h of long-term photocatalytic stability, indicating its potential as a promising and feasible candidate for the future development of renewable synthetic fuels.

Enhanced catalytic performance for CO2 cycloaddition and Knoevenagel condensation reactions via stable Eu3+ modified Mn-MOF

The construction of MOF-based catalysts containing simultaneous Lewis acid and Lewis base sites has been considered as an efficient approach to enhance chemical fixation of CO2 into value-added products and Knoevenagel condensation reaction. Herein, one novel Eu3+-modified Mn-MOF (Eu3+@Mn-MOF-1) was successfully synthesized by solvothermal synthesis and post-synthesis modification. In Mn-MOF-1, the alternating chains with single and double carboxylate bridges are connected by H2L4− ligands to form a three-dimensional framework with 1D channels along a axis. Interestingly, the activated state of Eu3+@Mn-MOF-1 (noted as Eu3+@Mn-MOF-1a) with the removal of coordinated and lattice H2O molecules displayed excellent thermal stability. Furthermore, it is worth emphasizing that the inner surfaces of Eu3+@Mn-MOF-1a are functionalized by pentiful Lewis acid sites (tri- and penta-coordinated Mn2+ ions and modified Eu3+ ions) and Lewis base sites (uncoordinated Ocarboxylate and Npyridine). By virtue of the abundant co-existing Lewis acid-base sites, Eu3+@Mn-MOF-1a exhibited high catalytic performance for the cycloaddition of CO2 with epoxides and Knoevenagel condensation of aldehydes and malononitrile with preferable repeatability under mild conditions without the requirement of any solvent. Moreover, Eu3+@Mn-MOF-1a performed much higher activity for the cycloaddition of CO2 with epoxides than Mn-MOF-1a under the same conditions. In addition, Eu3+@Mn-MOF-1a also shows the yield of benzylidenemalononitrile can reach 99.9 % at room temperature within 1 h, representing about 1.3-fold increase compared to that of Mn-MOF-1a (76.0 %). The improvement of catalytic performance suggested the contribution of Eu3+ ions to the reaction. Hence, this work provides an efficient approach for the construction of MOFs with Lewis base sites by elaborately designing organic ligands and Lewis acid sites by post-synthetic modification to expose and/or introduce more unsaturated metal sites.

Numbers of Exchangeable Hydrogens from LC-MS Data of Heavy Water Metabolically Labeled Samples.

Labeling with deuterium oxide (D2O) has emerged as one of the preferred approaches for measuring the synthesis of individual proteins in vivo. In these experiments, the synthesis rates of proteins are determined by modeling mass shifts in peptides during the labeling period. This modeling depends on a theoretical maximum enrichment determined by the number of labeling sites (NEH) of each amino acid in the peptide sequence. Currently, NEH is determined from one set of published values. However, it has been demonstrated that NEH can differ between species and potentially tissues. The goal of this work was to determine the number of NEH for each amino acid within a given experiment to capture the conditions unique to that experiment. We used four methods to compute the NEH values. To test these approaches, we used two publicly available data sets. In a de novo approach, we compute NEH values and the label enrichment from the abundances of three mass isotopomers. The other three methods use the complete isotope profiles and body water enrichment in deuterium as an input parameter. They determine the NEH values by (1) minimizing the residual sum of squares, (2) from the mole percent excess of labeling, and (3) the time course profile of the depletion of the relative isotope abundance of monoisotope. In the test samples, the method using residual sum of squares performed the best. The methods are implemented in a tool for determining the NEH for each amino acid within a given experiment to use in the determination of protein synthesis rates using D2O.

Switching approximate insulator into semiconductor: Ultrasensitive and rapid triethylamine detections based on In3+ inserted MOF-76 (Nd) derived nanocomposites

Triethylamine (TEA) poses significant risks to both environmental quality and human health. Hence, in this work, we employed an ionic-inserted MOF-derived method to synthesize Nd2O2CO3-based nanocomposites. Electronic structure modulations of Nd2O2CO3 from approximate insulators into semiconductors were realized by In3+ intercalations, which profoundly reduces bandgap and facilitates electron transferring. Adequate oxygen vacancies and Lewis acidity sites in Nd2O2CO3 provide more active sites for TEA reactions. Leveraging defect engineering and electronic structure modulation, the optimized sensor exhibited a considerable TEA response (167.94), rapid responding/recovering (5/42 s) at low temperature (160 ℃). Furthermore, the intensive CO2 adsorption capabilities of Nd2O2CO3 and the abilities to react between TEA and CO2 were confirmed by In-situ DRIFTS thereby certificating the availability of sensors in an atmospheric environment with exceptional anti-interference capability. This work not only develops novel TEA sensing materials but also proposes feasible strategies for optimizing TEA sensing characteristics through ion intercalation.

Polyaniline-based bovine serum albumin imprinted electrochemical sensor for ultra-trace-level detection in clinical and food safety applications

Monitoring bovine serum albumin (BSA) at ultra-low levels is crucial for clinical and food safety applications, as it plays a significant role in identifying various health conditions and potential risks, necessitating fast, trace-level detection of BSA. This study proposes an approach to address these challenges by employing molecularly imprinted polymer (MIP) to develop an ultra-trace-level and cost-effective BSA sensing platform. The MIP electrochemical sensor was developed using polyaniline (PANI) combined with the protein crosslinker glutaraldehyde (GA) to optimize BSA surface imprinting in the MIP. As a result, the sensor achieves a sensitivity of 1.24 μA/log(pg/mL), with a picomolar detectable limit of 2.3 pg/mL (0.035 pM) and a wide detection range from 20 pg/mL to 200,000 pg/mL (0.303 pM to 3030 pM), making it suitable for clinical and food safety applications. Additionally, the study explores the interaction between an acidic surfactant protein eluent (acetic acid with sodium dodecyl sulfate, AcOH-SDS) and BSA vacant sites, enhancing recognition and re-binding. The PANI-based MIP sensor demonstrates initial feasibility and practicality in commercial milk and real human serum, opening avenues for early disease detection and ensuring food safety in BSA-related immune responses.

An experimental and density functional theory investigation of the influence of HZSM-5 on pyrolysis oils produced from vanillin, a model lignin compound

Lignin, as a renewable energy source, has attracted much attention due to its high valorization potential. Due to the complex composition of lignin, vanillin, an important intermediate of lignin, was chosen as a model compound in this study. The study examined the influence of the HZSM-5 molecular sieve on the quality of pyrolysis oils during the catalytic pyrolysis of vanillin at 600 °C using a horizontal tube furnace and Py-GC/MS analysis. The results revealed that the HZSM-5 catalyst significantly increased the yields of toluene, guaiacol, and 4-hydroxyisophthalaldehyde by 2.49 %, 19.26 %, and 1.8 %, respectively, whereas reducing the contents of phenol and 3,4-dimethoxyphenol by 6.01 % and 3.79 %, respectively. These findings indicate that the HZSM-5 molecular sieve effectively improves the quality of pyrolysis oils during the catalytic pyrolysis of vanillin. The evolution of the main functional groups in the pyrolysis of vanillin was analyzed using an in situ diffuse reflectance infrared Fourier transform spectroscopy. The addition of HZSM-5 promoted the cleavage of oxygen-containing functional groups and the generation of aromatic hydrocarbons during the pyrolysis of vanillin. Furthermore, the pyrolysis reaction pathways of vanillin were simulated under the B3LYP/6-311 g (d, p) basis set using the density functional theory. The acidic sites of HZSM-5 interacted with vanillin via the hydrogen bonds that affected the energy barriers of the pyrolysis reaction pathways of vanillin. HZSM-5 inhibited the generation of phenol and 3,4-dimethoxyphenol by increasing the energy barriers by 32.95 and 31.03 kJ/mol, respectively; however, HZSM-5 promoted toluene production by decreasing the energy barrier by 37.38 kJ/mol. The effects of HZSM-5 on the products in the simulation results were consistent with the experimental results.

Active site modulation in UiO-66(Ce) MOFs by Al3+ doping for boosting photocatalysis

A series of Al3+-doped UiO-66(Ce) MOFs (U(CexAl1−x)) was developed to reveal the roles of metal doping on active site formation and substrate activation in photocatalytic selective transformation of amines to imines. Al3+ doping induced crystal structure distortion to form coordinately unsaturated metal (Al, Ce) sites as Lewis acid sites to chemisorb and activate benzylamine (BA). In situ FTIR revealed that the Al site with stronger acid strength facilitated BA activation. The activation degree of N–H bonds in BA was evaluated by changes of calculated force constant. The intermediate products were confirmed through time-dependent in situ FTIR. The Al3+-doped sample U(Ce0.90Al0.10), the optimal catalyst, showed a significantly increased BA conversion (97.6 %) than that (47.5 %) of undoped sample, which was attributed to enough active sites and the optimal charge mobility. Finally, the present study proposes a synergistic photocatalytic mechanism associated with molecular activation to demonstrate selective oxidation pathways at the molecular level.

Robust heterometallic {In2CdO}-Organic framework for efficiently catalyzing CO2 cycloaddition and Knoevenagel condensation

The catalytic performance of MOFs mainly comes from the coordination defects of their metal ions. However, developing promising MOF catalysts with a large number of small coordination molecules on metal ions remains a huge challenge. Herein, we report a highly robust heterometallic {In2CdO}-organic framework of {[In2Cd(CPPDP)(µ3 − OH)(H2O)5](NO3)2⋅2DMF⋅3H2O}n (NUC-103) with scarcely reported [In2Cd(OH)(O2CR)5(H2O)5] clusters (abbreviated as {In2CdO}) as secondary building units (SBUs), each of which contains five associated water molecules, implying that activated host framework can serve as strong Lewis acid. In NUC-103, three rows of {In2CdO} are shaped into hierarchical triangle-nanochannels of 17.42 × 17.98 Å2 and triangle-microchannels of 10.15 × 11.00 Å2 along c axis. On account of the following unique characteristics such as three kinds of active sites (Lewis acid sites of In3+ and Cd2+, Lewis base sites of free Npyridine atoms and electrophilic H-bond donors (HBD) of µ3 − OH moieties), large solvent-free channels, high thermal stability, and resistance to various solvents, NUC-103a is a promising catalytic platform. Catalytic experiments prove that NUC-103a is a significant heterogeneous catalyst for the cycloaddition of CO2 with epoxides with exclusive selectivity and high conversion. In addition, NUC-103a as a bifunctional catalyst displays the high catalytic performance on the Knoevenagel condensation reactions of aldehydes and malononitrile. Therefore, this work not only provides an indium(III) + cadmium(II)-based heterometallic cluster of {In2CdO}, but also provides a valuable insight into designing metal–organic catalytic materials with high defect coordination.