Nonionic polymer and amino acid-assisted synthesis of ZSM-5 nanocrystals and their catalytic application in the alkylation of 2-methylnaphthalene.

The synthesis of nanosized ZSM-5 zeolites with high crystallinity and suitable acidity is very significant for their great potential in various catalytic applications. Herein, a series of zeolite ZSM-5 crystals with different particle sizes and SiO2/Al2O3 ratios (10-30) were synthesized by a temperature-varying two-step crystallization method in a concentrated gel system containing L-lysine and/or polyvinylpyrrolidone (PVP) additives. By optimizing the addition amounts of the two additives, the crystal size of the ZSM-5 zeolite could be reduced to less than 100 nm. Meanwhile, relatively high crystallinity and framework Al incorporation rates could be achieved, resulting in the generation of high-quality ZSM-5 nanocrystals. The nanosized H-form ZSM-5 zeolite with a SiO2/Al2O3 ratio of 20 showed enhanced catalytic efficiency and stability for the alkylation of 2-methylnaphthalene (2-MN) with methanol to produce an important intermediate, 2,6-dimethylnaphthalene (2,6-DMN). A relatively high and steady yield of 2,6-DMN (above 7.2%) could be achieved during 20 h time-on-stream at 400 °C. The smaller crystal size, higher crystallinity and framework Al content could provide more accessible Brønsted acid sites in the 10-membered ring channel of the ZSM-5 nanocrystals, which are the main active sites responsible for the shape-selectivity of the targeted product of 2,6-DMN. As a result, the formation of other side products like 1-MN and poly-MN could be effectively inhibited, thus leading to an improved 2,6-DMN yield and coke resistance over the nanosized ZSM-5 catalyst.

Fulminant myocarditis induced by SARS-CoV-2 infection without severe lung involvement: insights into COVID-19 pathogenesis.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection often leads to pulmonary complications. Cardiovascular sequelae, including myocarditis and heart failure, have also been reported. Here, the study presents two fulminant myocarditis cases infected by SARS-CoV-2 exhibiting remarkable elevation of cardiac biomarkers without significant pulmonary injury, as determined by imaging examinations. Immunohistochemical staining reveals the viral antigen within cardiomyocytes, indicating that SARS-CoV-2 could directly infect the myocardium. The full viral genomes from respiratory, anal, and myocardial specimens are obtained via next-generation sequencing. Phylogenetic analyses of the whole genome and spike gene indicate that viruses in the myocardium/pericardial effusion and anal swabs are closely related and cluster together yet diverge from those in the respiratory samples. In addition, unique mutations are found in the anal/myocardial strains compared to the respiratory strains, suggesting tissue-specific virus mutation and adaptation. These findings indicate genetically distinct SARS-CoV-2 variants have infiltrated and disseminated within myocardial tissues, independent of pulmonary injury, and point to different infection routes between the myocardium and respiratory tract, with myocardial infections potentially arising from intestinal infection. These findings highlight the potential for systemic SARS-CoV-2 infection and the importance of a thorough multi-organ assessment in patients for a comprehensive understanding of the pathogenesis of COVID-19.

Anti-infection effects of heparin on SARS-CoV-2 in a diabetic mouse model.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can result in more severe syndromes and poorer outcomes in patients with diabetes and obesity. However, the precise mechanisms responsible for the combined impact of corona virus disease 2019 (COVID-19) and diabetes have not yet been elucidated, and effective treatment options for SARS-CoV-2-infected diabetic patients remain limited. To investigate the disease pathogenesis, K18-hACE2 transgenic (hACE2 Tg) mice with a leptin receptor deficiency (hACE2-Lepr -/-) or high-fat diet (hACE2-HFD) background were generated. The two mouse models were intranasally infected with a 5×10 5 median tissue culture infectious dose (TCID 50) of SARS-CoV-2, with serum and lung tissue samples collected at 3 days post-infection. The hACE2-Lepr -/- mice were then administered a combination of low-molecular-weight heparin (LMWH) (1 mg/kg or 5 mg/kg) and insulin via subcutaneous injection prior to intranasal infection with 1×10 4 TCID 50 of SARS-CoV-2. Daily drug administration continued until the euthanasia of the mice. Analyses of viral RNA loads, histopathological changes in lung tissue, and inflammation factors were conducted. Results demonstrated similar SARS-CoV-2 susceptibility in hACE2 Tg mice under both lean (chow diet) and obese (HFD) conditions. However, compared to the hACE2-Lepr +/+ mice, hACE2-Lepr -/- mice exhibited more severe lung injury, enhanced expression of inflammatory cytokines and hypoxia-inducible factor-1α, and increased apoptosis. Moreover, combined LMWH and insulin treatment effectively reduced disease progression and severity, attenuated lung pathological changes, and mitigated inflammatory responses. In conclusion, pre-existing diabetes can lead to more severe lung damage upon SARS-CoV-2 infection, and LMWH may be a valuable therapeutic approach for managing COVID-19 patients with diabetes.

A metal-organic framework with rich accessible nitrogen sites for rapid dye adsorption and highly efficient dehydrogenation of formic acid.

MOFs with adequate free nitrogen sites have potential applications in dye adsorption and formic acid dehydrogenation. Here, we successfully synthesized a novel 3-D MOF 1 ([(CH3)2NH2][Cd(L)DMA]·0.5DMA·1.5H2O) with a special two-fold interpenetrating framework through a simple solvothermal reaction between CdCl2·1.5H2O and a nitrogen-rich triangular tricarboxylate-based linker (H3L, 4,4',4''-s-triazine-2,4,6-tribenzoic acid). After removing the guest molecules of dimethylacetamide (DMA) and H2O, including the coordinated DMA from 1 by vacuum activation at 423 K, a compound named 1' with a formula of [(CH3)2NH2][Cd(L)] and a similar interpenetrating framework structure was obtained. In comparison with compound 1, the total void volume of 1' is nearly doubled, and thus may provide higher potential for the adsorption of other guest molecules. Notably, the pyridine N atoms located in the middle of the triangular tricarboxylate-based linker are not involved in the coordination with Cd2+, and are all uniformly dispersed throughout the whole framework of the 3-D MOFs. Due to its unique structural features, the 3-D MOF 1' could effectively adsorb the cationic dye MB+ for recycling purposes. The rapid adsorption rate (0.7 × 10-2 g mg-1 min-1) and the relatively high capacity (900 mg g-1) for MB+ demonstrate the potential of 1' in dye adsorption. In addition, 1' may also be used as an effective support to immobilize PdAu NPs via the double-solvent method. The resultant catalyst Pd0.8Au0.2/1' exhibits decent catalytic activity for the dehydrogenation of formic acid with a TOF value of 1854 h-1 at 333 K. The existence of a large void volume and accessible pyridine N atoms provide a suitable environment for achieving a high dispersion of PdAu NPs, thereby leading to the formation of a catalytically active and stable supported noble-metal NP catalyst for H2 generation from formic acid decomposition.

Porous 3,4-di(3,5-dicarboxyphenyl)phthalate-based Cd2+ coordination polymer and its potential applications.

Porous coordination polymers with organic aminium as one of the guest species possess a potential application in dye adsorption and white-light material manufacture. Polycarboxylic acid with multiple COOH substituents tends to form this type of porous material (with metal ion). Here the solvothermal self-assembly between Cd2+ and a hexacarboxylic acid creates such a porous material [(CH3)2NH2]6[Cd3(L)2]·5DMF·3H2O (H6L = 3,4-di(3,5-dicarboxyphenyl)phthalic acid) 1. Total potential guest accessible void volume in 3-D 1 is found to be 4327 Å3. Based on its better porous structure and stability, the ability of 1 to adsorb organic dyes is investigated. It has been proved that (i) 1 can selectively adsorb cationic dyes as Azure A (AA+) and/or Methylene Blue (MB+), rather than neutral and anionic ones; (ii) the maximum adsorption capacity is 698.2 mg·g-1 for AA+ and 573.2 mg·g-1 for MB+, respectively; and (iii) to the adsorption of AA+, it can be recycled for at least five rounds. Also, it is utilized to fabricate the while-light emitting material. Based on the blue-light emission of 1, the trace Eu3+ and Tb3+ ions are introduced into the pores of 1 successfully, obtaining a white-light emitting material Eu3+/Tb3+@1 (CIE chromaticity coordinates: (0.33, 0.32)). Meanwhile, Eu3+/Tb3+@1 is found to be a potential fluorescence photochromic material, showing a yellow-white-blue light emission. According to these investigations, the relationship between material structure and its adsorption property for dyes, the points that should be paid attention to in the construction of white-light emitting materials as well as the potential adsorption mechanism for dyes and rare earth ions are deeply discussed.

Nitrogen-doped carbon supported ZnO as highly stable heterogeneous catalysts for transesterification synthesis of ethyl methyl carbonate.

Nitrogen-doped carbon material (NCM) supported ZnO catalysts were prepared by wet impregnation method, following a high-temperature thermal treatment process. The resultant ZnO/NCM catalysts calcined at different temperatures were characterized by X-ray diffraction (XRD), Raman spectroscopy, N2 adsorption-desorption, elemental analysis, X-ray photoelectron spectroscopy (XPS) to investigate their physicochemical properties and the interaction between ZnO and NCM support. Their catalytic properties were studied by liquid phase transesterification of dimethyl carbonate (DMC) with diethyl carbonate (DEC). Of these the catalyst calcined at 800 °C, named ZnO/NCM-800 exhibits the highest catalytic activity, as well as excellent stability and recyclability for the synthesis of ethyl methyl carbonate (EMC). The NCM support possesses abundant mesopores, rich surface oxygen-containing and nitrogen-containing functional groups, which are beneficial to build relatively strong interaction between ZnO nanoparticles and the NCM support, resulting in the generation of a highly active and stable acidic-basic bifunctional catalyst for the transesterification of DMC with DEC.

Controlling the Morphology and Titanium Coordination States of TS-1 Zeolites by Crystal Growth Modifier.

Developing an effective strategy to synthesize perfect titanosilicate TS-1 zeolite crystals with desirable morphologies, enriched isolated framework Ti species, and thus enhanced catalytic oxidation properties is a pervasive challenge in zeolite crystal engineering. We here used an amino acid l-carnitine as a crystal growth modifier and ethanol as a cosolvent to regulate the morphologies and the Ti coordination states of TS-1 zeolites. During the hydrothermal crystallization process, the introduced l-carnitine can not only tailor the anisotropic growth rates of zeolite crystals but also induce the formation of uniformly distributed framework Ti species through building a suitable chemical interaction with the Ti precursor species. Condition optimizations could afford the generation of perfect hexagonal plate TS-1 crystals and elongated platelet TS-1 crystals enriched in tetrahedral framework Ti sites (TiO4) or mononuclear octahedrally coordinated Ti species (TiO6). Both samples showed significant improvement in catalytic activity for the H2O2-mediated epoxidation of alkenes. In particular, the elongated platelet TS-1 enriched in "TiO6" species afforded the highest activity in 1-hexene epoxidation, with a turnover frequency (TOF) of up to 131 h-1, which is approximately twice as high as that of the conventional TS-1 zeolite (TOF: 65 h-1) and even higher than those of the literature-reported TiO6-containting TS-1 catalysts derived from the hydrothermal post-treatment of TS-1 zeolites. This work demonstrates that the morphologies and the titanium coordination states of TS-1 zeolites can be effectively tuned by directly introducing suitable crystal growth modifiers, thus providing new opportunities for developing highly efficient titanosilicate zeolite catalysts for important catalytic applications.

Use of Amidoxime Polyacrylonitrile Bead-Supported Pd-Based Nanoparticles as High Efficiency Catalysts for Dehydrogenation of Formic Acid.

Amidoxime polyacrylonitrile (AOPAN) beads with diameter of around 2 mm were prepared by a simple ball-dropping method, and were used as support for the immobilization of Pd or PdNi nanoparticles for catalytic application in formic acid dehydrogenation. The Pd-based nanoparticles showed uniform distribution on the surface of the AOPAN beads, with good accessibility to reagents. The optimized PdNi/AOPAN catalyst can efficiently convert formic acid to hydrogen with a turn over frequency of 3041 h-1 under ambient conditions, and this catalytic activity was maintained well for at least seven cycles. The millimeter-sized beads can float on water, making them easy to manipulate and recover without any weight loss. The amidoxime and cyano groups on the surface of the AOPAN beads play critical roles in stabilizing and distributing Pd-based nanoparticles, and may also participate in the synergistic activation of formic acid dehydrogenation.

Hybrid compounds assembled from copper-triazole complexes and phosphomolybdic acid as advanced catalysts for the oxidation of olefins with oxygen.

Two hybrid compounds, namely [Cu(3atrz)4][PMoMoVO40] (1) and [Cu(3atrz)6][PMo12O40]2 (2), were synthesized through hydrothermal reactions of 3-amino-1,2,4-triazole (3atrz), phosphomolybdic acid (PMA) and appropriate copper salts. Crystal structure analysis reveals that compound 1 contains one-dimensional Cu-3atrz chains. The unit of compound 2 contains a double calyx[3]arene-shaped hexamer, which is composed of six two-coordinated CuI atoms and six 3atrz ligands. Both compounds 1 and 2 present a three-dimensional hybrid structure, which is built by the self-assembly of Cu-3atrz clusters and Keggin-type PMA units. The resulting hybrid compounds can act as highly efficient heterogeneous catalysts for the selective oxidation of olefins with molecular oxygen as the oxidant in the presence of a trace amount of tert-butyl hydroperoxide (t-BuOOH). Their excellent catalytic properties can be mainly attributed to the existence of stabilized CuI complexes with an appropriate chemical environment and a spacious structure, which can interact with t-BuOOH to form catalytic sites for the direct activation of O2. This work demonstrates that the hybrid compounds assembled from copper-3atrz complexes and phosphomolybdic acid may have great potential in molecular O2-mediated catalytic oxidation reactions, which can certainly build a platform for deep insight into the biologically relevant catalytic oxidation processes.

N-doped nanoporous carbon as efficient catalyst for nitrobenzene reduction in sulfide-containing aqueous solutions.

Metal-free N-doped porous carbon (NC) materials have been demonstrated to be promising catalysts in contaminated environment remediation. Two NC materials (NC-1 and NC-2) were prepared by sol-gel routes. Their catalytic properties were investigated for the reduction of nitrobenzene (NB) in sulfide-containing aqueous solution. Both NC-1 and NC-2 can efficiently catalyze the reduction of NB to aniline (AN) under ambient conditions, but also can be reused for more than 5 times. The reaction fits excellently to the pseudo-first-order kinetic. Compared with NC-1 material, NC-2 shows much higher removal efficiency (rate constant kobs: 0.283h-1vs. 2.50h-1). The important features of NC material, including high specific surface area, suitable surface functional groups (especially nitrogen-containing groups), and enhanced electron transfer ability, should be mainly factors for its excellent catalytic activity. This work demonstrates that N-doped carbon materials have great potential for degradation of NB to AN in the natural aquatic environment.

Electrochemical Synthesis and Catalytic Properties of Encapsulated Metal Clusters within Zeolitic Imidazolate Frameworks.

It is very interesting and also a big challenge to encapsulate metal clusters within microporous solids to expand their application diversity. For this target, herein, we present an electrochemical synthesis strategy for the encapsulation of noble metals (Au, Pd, Pt) within ZIF-8 cavities. In this method, metal precursors of AuCl42- , PtCl62- , and PdCl42- are introduced into ZIF-8 crystals during the concurrent crystallization of ZIF-8 at the anode. As a consequence, very small metal clusters with sizes around 1.2 nm are obtained within ZIF-8 crystals after hydrogen reduction; these clusters exhibit high thermal stability, as evident from the good maintenance of their original sizes after a high-temperature test. The catalytic properties of the encapsulated metal clusters within ZIF-8 are evaluated for CO oxidations. Because of the small pore window of ZIF-8 (0.34 nm) and the confinement effect of small pores, about 80 % of the metal clusters (fractions of 0.74, 0.77, and 0.75 for Au, Pt, and Pd in ZIF-8, respectively) retain their catalytic activity after exposure to the organosulfur poison thiophene (0.46 nm), which is in contrast to their counterparts (fractions of 0.22, 0.25, and 0.20 for Au, Pt, and Pd on the SiO2 support). The excellent performances of metal clusters encapsulated within ZIF-8 crystals give new opportunities for catalytic reactions.

Room Temperature CO Oxidation over Pt/MgFe2O4: A Stable Inverse Spinel Oxide Support for Preparing Highly Efficient Pt Catalyst.

MgFe2O4 with inverse spinel structure is demonstrated to be an efficient support for constructing practical potential Pt catalyst (Pt/MgFe2O4). The resultant Pt/MgFe2O4 exhibits excellent catalytic behavior in CO oxidation under normal temperature and humidity. TOF calculated based on the content of Pt is 0.131 s-1. The excellent performance of Pt/MgFe2O4 attributes to the presence of surface undercoordinated lattice oxygens on MgFe2O4 support. These oxygens could participate in the initial CO oxidation and then be recovered under O2 conditions. Over this Pt/MgFe2O4 catalyst, CO catalytic oxidation should mainly follow a redox mechanism.

A non-chemically selective top-down approach towards the preparation of hierarchical TS-1 zeolites with improved oxidative desulfurization catalytic performance.

Hierarchical TS-1 zeolites with secondary macropores have been successfully prepared by using two different fluoride-containing chemical etching post-treated routes. Hierarchical TS-1 zeolites exhibited a chemical composition similar to that of the parent material and showed remarkably enhanced catalytic activity in oxidative desulfurization reaction.

A green surfactant-assisted synthesis of hierarchical TS-1 zeolites with excellent catalytic properties for oxidative desulfurization.

Hierarchical TS-1 zeolites with uniform intracrystalline mesopores have been successfully synthesized through the hydrothermal method by using the green and cheap surfactant Triton X-100 as the mesoporous template. The resultant materials exhibit remarkably enhanced catalytic activity in oxidative desulfurization reactions compared to the conventional TS-1 zeolite.

Adsorption behaviors of methyl orange dye on nitrogen-doped mesoporous carbon materials.

A series of nitrogen-doped mesoporous carbon materials (NMC) with different nitrogen contents (from 9.1 to 11.3 wt.%) were prepared using urea and ammonia as economical nitrogen resources by sol-gel method. The NMC materials possessed high surface areas (from 659 m(2)/g to 912 m(2)/g) as well as large number of oxygen-containing and nitrogen-containing groups. The adsorption behaviors of NMC materials for anionic dye methyl orange (MO) were investigated, which are fit excellent for the Langmuir isothermal adsorption equation. All the materials exhibited high adsorption capacity for MO at room temperature. Their adsorption capacity can be adjusted by changing the nitrogen contents in NMC materials. Moreover, treating the NMC material at higher temperature can significantly improve the adsorption capacity for MO. According to the results of characterization, the main features of NMC materials, like large pore size and abundant basic nitrogen-containing groups on the surface, should be related to the excellent adsorption property for MO.

Synthesis of dendritic iridium nanostructures based on the oriented attachment mechanism and their enhanced CO and ammonia catalytic activities.

Branched iridium nanodendrites (Ir NDs) have been synthesized by a simple method based on the oriented attachment mechanism. Transmission electron microscopy images reveal the temporal growth process from small particles to NDs. Precursor concentrations and reaction temperatures have a limited effect on the morphology of Ir NDs. Metal oxide and hydroxide-supported Ir NDs exhibit enhanced activity for catalytic CO oxidation. Particularly, the Fe(OH)x-supported Ir NDs catalyst with a 4 wt% Ir loading show superior CO oxidation catalytic activity with a full conversion of CO at 120 °C. Furthermore, compared with Ir NPs and commercial Ir black, Ir NDs exhibit higher activity and stability for ammonia oxidation. The specific activity and mass activity of Ir NDs for ammonia oxidation are 1.7 and 7 times higher than that of Ir NPs. The improved catalytic activities of Ir NDs are attributed not only to their large specific surface area, but also to their considerably high index facets and rich edge and corner atoms. Hence, the obtained Ir NDs provide a promising alternative for direct ammonia fuel cells and proton-exchange membrane fuel cells.

Correlation between the microstructures of graphite oxides and their catalytic behaviors in air oxidation of benzyl alcohol.

A series of graphite oxide (GO) materials were obtained by thermal treatment of oxidized natural graphite powder at different temperatures (from 100 to 200 °C). The microstructure evolution (i.e., layer structure and surface functional groups) of the graphite oxide during the heating process is studied by various characterization means, including XRD, N2 adsorption, TG-DTA, in situ DRIFT, XPS, Raman, TEM and Boehm titration. The characterization results show that the structures of GO materials change gradually from multilayer sheets to a transparent ultrathin 2D structure of the carbon sheets. The concentration of surface COH and HOCO groups decrease significantly upon treating temperature increasing. Benzyl alcohol oxidation with air as oxidant source was carried out to detect the catalytic behaviors of different GO materials. The activities of GO materials decrease with the increase of treating temperatures. It shows that the structure properties, including ultrathin sheets and high specific surface area, are not crucial factors affecting the catalytic activity. The type and amount of surface oxygen-containing functional groups of GO materials tightly correlates with the catalytic performance. Carboxylic groups on the surface of GO should act as oxidative sites for benzyl alcohol and the reduced form could be reoxidized by molecular oxygen.

Highly dispersed iron oxides on mesoporous carbon for selective oxidation of benzyl alcohol with molecular oxygen.

Highly dispersed iron oxide supported catalysts, prepared using HNO3-treated CMK-3 mesoporous carbons as supports, exhibit relatively high catalytic activity in selective oxidation of benzyl alcohol with oxygen.

Facile synthesis of mesoporous spinel NiCo2O4 nanostructures as highly efficient electrocatalysts for urea electro-oxidation.

Mesoporous spinel nickel cobaltite (NiCo2O4) nanostructures were synthesized via a facile chemical deposition method coupled with a simple post-annealing process. The physicochemical properties were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS) and nitrogen sorption measurements. The electrocatalytic performances were investigated by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) tests. The obtained NiCo2O4 materials exhibit typical agglomerate mesoporous nanostructures with a large surface area (190.1 m(2) g(-1)) and high mesopore volume (0.943 cm(3) g(-1)). Remarkably, the NiCo2O4 shows much higher catalytic activity, lower overpotential, better stability and greater tolerance towards urea electro-oxidation compared to those of cobalt oxide (Co3O4) synthesized by the same procedure. The NiCo2O4 electrode delivers a current density of 136 mA cm(-2) mg(-1) at 0.7 V (vs. Hg/HgO) in 1 M KOH and 0.33 M urea electrolytes accompanied with a desirable stability. The impressive electrocatalytic activity is largely ascribed to the high intrinsic electronic conductivity, superior mesoporous nanostructures and rich surface Ni active species of the NiCo2O4 materials, which can largely boost the interfacial electroactive sites and charge transfer rates for urea electro-oxidation, indicating promising applications in future wastewater remediation, hydrogen production and fuel cells.