Effect of Cu-Doped Co-Mn Spinel for Boosting Low-Temperature NO Reduction by CO: Exploring the Structural Properties, Performance, and Mechanisms.

Cobalt-manganese spinel catalysts performed unsatisfactory activity at low-temperature and narrow reaction temperature window, which greatly limited the application in NO reduction by CO. Herein, we synthesize a series of Cu-doped CoMn2O4 catalysts and apply to NO reduction by CO. The Cu0.3Co0.7Mn2O4 exhibited superior catalytic performance, reaching 100% NO conversion and 80% N2 selectivity at 250 °C. Detailed structural analysis showed that the introduced Cu replaces some Co in tetrahedral coordination to induce a strong synergistic effect between different metals. This endows the catalyst with the promotion of both electron transfer and oxygen vacancy generation on the catalyst surface. Importantly, the reaction mechanism and pathway were further revealed by in situ diffusion Fourier transform infrared spectroscopy (DRIFTS) and density functional theory (DFT) calculations. The results indicated that the cycle of oxygen vacancy mainly determines the catalytic activity of NO reduction by CO. Notably, Cu doping significantly lowered the energy barrier of the rate-determining step (*CO + O → *Ov + CO2), facilitating the desorption of the CO2 and exposing the active sites for efficient NO reduction with CO. This work offers an effective way for designing the catalyst in NO reduction by CO and provides a reference for exploring the catalytic mechanism of the reaction.

Prognostic Analysis of LncRNA MCM3AP-AS1 in Colorectal Cancer and the Mechanism of Its Effect on Tumor Cell Activity.

To determine the clinical prognostic significance of lncRNA MCM3AP-AS1 in colorectal cancer (CRC) and its preliminary mechanism, 43 CRC patients and 48 healthy individuals were analyzed. Peripheral blood MCM3AP-AS1 was quantified via qRT-PCR in CRC patients at admission and 2 h after surgery and in healthy individuals. Human colon cancer cells (HCT116 and SW480) were transfected with shRNAs targeting upregulation of MCM3AP-AS1 expression (named as sh-MCM3AP-AS1 group) and corresponding negative RNAs (named as sh-MCM3AP-AS1 group). Additionally, the cells were then treated either with 50 mM of the VEGF-specific inhibitor PTK787 (Selleck, USA) (named as inhibition group) or normal saline as a control (named as control group). Before therapy, CRC patients presented a higher MCM3AP-AS1 level than healthy individuals (P < 0.05), and the sensitivity and specificity of MCM3AP-AS1 in predicting the occurrence of CRC were 65.12% and 83.33%, respectively (P < 0.001). After therapy, CRC patients presented a decrease in MCM3AP-AS1 levels, and recurrence was higher in patients who died (P < 0.05). Additionally, the high MCM3AP-AS1 expression group presented a higher mortality than the low MCM3AP-AS1 expression group (P < 0.05). In an in vitro assay, CRC cells showed a higher MCM3AP-AS1 level than CCD-18Co cells, and the sh-MCM3AP-AS1 group presented decreased cell proliferation and invasiveness, whereas the levels apoptosis-associated proteins were increased (P < 0.05). Moreover, the VEGF and VEGFR2 mRNA levels were increased in CRC cells, and VEGF/VEGFR2 pathway-associated proteins were inhibited in the sh-MCM3AP-AS1 group (P < 0.05). Moreover, treatment with PTK787 decreased cell proliferation and invasivness but increased the levels of apoptosis-associated proteins (P < 0.05).

Development of cerium oxide-based diffusive gradients in thin films technique for in-situ measurement of dissolved inorganic arsenic in waters.

A diffusive gradients in thin films (DGT) method using a new high-capacity cerium oxide (CeO2) binding gel, for the first time, was developed for measuring dissolved inorganic arsenic in freshwater and seawater. The capacities of the new CeO2 binding gel were 682 µg and 375 µg for AsIII and AsV, respectively. The masses of AsIII and AsV accumulated by CeO2-DGT device increased linearly with time and agreed well with the theoretical value calculated by DGT equation. The arsenic accumulation by CeO2-DGT was independent of pH (4.05-9.04) and ionic strength (0.1-750 mM), and common anions including CO32-, SO42-, Cl- and PO43- had no obvious interference. CeO2-DGT showed excellent long-term deployment performance in freshwater and synthetic seawater. Field trials with CeO2-DGT achieved successfully the time-weighted-average concentrations of total inorganic arsenic in reservoir water (1.38 ±â€¯0.09 µg/L) and coastal seawater (0.45 ±â€¯0.06 µg/L). The results were comparable to those measured by grab sampling. The proposed method was reliable and robust for in-situ measurements of dissolved inorganic arsenic in environmental waters.

Triple-shelled NiMn2O4 hollow spheres as an efficient catalyst for low-temperature selective catalytic reduction of NOx with NH3.

Unique triple-shelled NiMn2O4 hollow spheres are fabricated by a facile solvothermal method. Owing to its particular triple shell structure, the as prepared NiMn2O4 catalyst exhibits superior low-temperature NH3-SCR catalytic performance, achieving above 90% NOx conversion in the temperature range from 100 °C to 225 °C.

3D mesoporous CuFe2O4 as a catalyst for photo-Fenton removal of sulfonamide antibiotics at near neutral pH.

Increasing the amount of surface active sites of the material may be a feasible way to improve the efficiency ofthe generation of Fe2+ in the photo-Fenton process. In this work, a simple synthesis method was adopted to synthesize 3D ordered mesoporous CuFe2O4 with large specific surface areaby using ferric nitrate and copper nitrate as the precursor and KIT-6 as the template. The synthesized materials were characterized by nitrogen adsorption-desorption, XRD, TEM, FT-IR and UV-vis DRS. The catalytic properties of the mesoporous material were thoroughly evaluated by activating hydrogen peroxide to remove sulfonamides in near neutral water. Some of the reaction factors, such as the dose of hydrogen peroxide, catalyst usage and pollute concentration, were cautiously tested and discussed. When the catalyst dose is 0.2 g/L, the substrate concentration is 10 mg/L and the concentration of hydrogen peroxide is 10 mM, sulfamethoxazole is almost completely transformed within two hours and its mineralization level reached 31.42%. In the further study of mechanism, hydroxyl radical is proved to be the main active free radical based on EPR. Moreover, mesoporous copper ferric has good circulation, which indicates that it may have excellent application in the field of photo-Fenton.

2D, 3D mesostructured silicas templated mesoporous manganese dioxide for selective catalytic reduction of NOx with NH3.

Employing nanocasting method, mesoporous MnO2 catalysts with large specific surface area and regular pore structure were synthesized by using three different types of mesostructure silicas (KIT-6, SBA-15, MCM-41) as hard templates. The physical and chemical properties of the three different mesostructured manganese oxide materials were comparatively and systematically characterized by using XRD, FT-IR, N2 adsorption-desorption, TEM, NH3-TPD, H2-TPR, XPS. The NH3-SCR performance of the mesoporous MnO2 was also evaluated on SCR self-assembly device. It was discovered that the mesostructure of the template would influence the amount and the kind of acid site, the reduction ability and then influence the catalytic performance of the materials. Mesoporous MnO2 templated from KIT-6 exhibited better catalytic performance than other mesoporous MnO2, indicating that the mesostructure of the materials has significant influence on the NH3-SCR performance. The KIT-6 templated MnO2 could induce 100% NOx conservation ratio range from 75 °C to 275 °C and exhibit good resistance of SO2 and H2O.

Improvement of Electrochemical Water Oxidation by Fine-Tuning the Structure of Tetradentate N4 Ligands of Molecular Copper Catalysts.

Two copper complexes, [(L1)Cu(OH2 )](BF4 )2 [1; L1=N,N'-dimethyl-N,N'-bis(pyridin-2-ylmethyl)-1,2-diaminoethane] and [(L2)Cu(OH2 )](BF4 )2 [2, L2=2,7-bis(2-pyridyl)-3,6-diaza-2,6-octadiene], were prepared as molecular water oxidation catalysts. Complex 1 displayed an overpotential (η) of 1.07 V at 1 mA cm-2 and an observed rate constant (kobs ) of 13.5 s-1 at η 1.0 V in pH 9.0 phosphate buffer solution, whereas 2 exhibited a significantly smaller η (0.70 V) to reach 1 mA cm-2 and a higher kobs (50.4 s-1 ) than 1 under identical test conditions. Additionally, 2 displayed better stability than 1 in controlled potential electrolysis experiments with a faradaic efficiency of 94 % for O2 evolution at 1.58 V, when a casing tube was used for the Pt cathode. A possible mechanism for 1- and 2-catalyzed O2 evolution reactions is discussed based on the experimental evidence. These comparative results indicate that fine-tuning the structures of tetradentate N4 ligands can bring about significant change in the performance of copper complexes for electrochemical water oxidation.

An electrochemically reduced graphene oxide chemiresistive sensor for sensitive detection of Hg2+ ion in water samples.

Divalent mercuric (Hg2+) ion is one of the most prevalent forms of mercury species in waters with high toxicity and bioaccumulation in the human body, for which sensitive and selective detection methods are highly necessary to carry out its recognition and quantification. Here an electrochemically reduced graphene oxide (RGO) based chemiresistive sensor was constructed and used for the detection of Hg2+ ion in various water samples. Monolayer GO sheets were assembled onto interdigitated electrodes, followed by reduction through linear sweep voltammetry and then modification with a single-stranded DNA aptamer. The electrochemically derived RGO based sensor showed selective response to as low as 0.5nMHg2+ ion in presence of other metal ions and matrices. A comparison between chemiresistive sensors prepared with electrochemically and chemically derived RGO showed that the former had better response performance for sensing Hg2+ ion. The proposed method provides a simple tool for rapid, selective and sensitive monitoring of Hg2+ ion in environmental samples.

Graphene oxide based in-tube solid-phase microextraction combined with liquid chromatography tandem mass spectrometry for the determination of triazine herbicides in water.

A novel in-tube solid-phase microextraction method based on a graphene oxide coated column was developed for the determination of triazines in waters. This column was prepared by the covalent modification of monolayer graphene oxide sheets onto the inner wall of a fused-silica capillary. Scanning electron microscopy showed that the thickness of the graphene oxide coating was ∼30 nm, with a porous, wrinkled membrane-like structure. Its performance was evaluated through the extraction of triazines in water. Results showed that the coating was stable for at least 100 replicate extractions, and variety of multi-columns was less than 10%. Flow rate, loading volume, pH, and ionic strength of samples played an important effect on the extraction. The high extraction efficiency was mainly attributed to π-π stacking and hydrogen bonding interactions. The in-tube solid-phase microextraction was used in the determination of triazines with liquid chromatography and tandem mass spectrometry, and the detection limits were 0.0005-0.005 µg/L for five triazine compounds. Further, the method was applied to the analysis of triazine herbicides in real samples including tap water, sea water, and river water, and the recoveries were 82.8-112.0, 85.4-110.5, and 81.6-105.9%, respectively, with RSDs of 2.7-7.1%.

Selective functionalization of hollow nanospheres with Acid and base groups for cascade reactions.

The inner-surface functionalization of hollow silica spheres has rarely been reported and is still a challenging topic. Herein, we report a deacetalization-Henry cascade reaction catalyzed by dual-functionalized mesoporous silica hollow nanospheres with basic amine groups (NH2 ) on the internal shell and carboxylic acid groups (COOH) on the external shell. The selective functionalization has been realized by a combination of "step-by-step post-grafting" and "cationic surfactant-assisted selective etching" strategy. Compared to unisolated catalyst, the selectively isolated acidic and basic dual catalyst provides excellent catalytic performance for the deacetalization-Henry cascade reaction in terms of both activity (>99 %) and selectivity (95 %).

Adsorption of ciprofloxacin, bisphenol and 2-chlorophenol on electrospun carbon nanofibers: in comparison with powder activated carbon.

Carbon nanofibers (CNFs) were prepared by electrospun polyacrylonitrile (PAN) polymer solutions followed by thermal treatment. For the first time, the influence of stabilization procedure on the structure properties of CNFs was explored to improve the adsorption capacity of CNFs towards the environmental pollutants from aqueous solution. The adsorption of three organic chemicals including ciprofloxacin (CIP), bisphenol (BPA) and 2-chlorophenol (2-CP) on electrospun CNFs with high surface area of 2326m(2)/g and micro/mesoporous structure characteristics were investigated. The adsorption affinities were compared with that of the commercial powder activated carbon (PAC). The adsorption kinetics and isotherms showed that the maximum adsorption capacities (qm) of CNFs towards the three pollutants are sequenced in the order of CIP>BPA>2-CP, which are 2.6-fold (CIP), 1.6-fold (BPA) and 1.1-fold (2-CP) increase respectively in comparison with that of PAC adsorption. It was assumed that the micro/mesoporous structure of CNFs, molecular size of the pollutants and the π electron interaction play important roles on the high adsorption capacity exhibited by CNFs. In addition, electrostatic interaction and hydrophobic interaction also contribute to the adsorption of CNFs. This study demonstrates that the electrospun CNFs are promising adsorbents for the removal of pollutants from aqueous solutions.

Azide-functionalized hollow silica nanospheres for removal of antibiotics.

Antibiotics, which are hardly removed from polluted water by conventional water-treatment technologies, adsorption has been deemed as one of the efficient and promising method to resolve the problems of antibiotics pollution. Herein, we reported a synthesis of filtration separable hollow nanostructured silicas (HNSs) with efficient click functionalization property for antibiotics adsorption. The clickable HNSs were synthesized by the co-condensation and assembling of tetramethoxysilane (TMOS) and 3-azidopropyltrimethoxysilane (AzPTMS) around F127 single micelle template. Alkynyl compounds such as phenylacetylene (Ph), propargyl alcohol (PA), 1-heptyne (Hep), and 2-butyne-1,4-diol (BD) have been linked to the materials through click reaction with high efficiency. Antibiotic adsorption results reveal that functional groups play an important role in adsorption properties of adsorbents and phenyl was found to be the optimal functional group due to the π-π stacking effect. Excellent adsorption capacity and recyclability indicate that the clickable hollow nanostructured silicas exhibit potential application for antibiotics removal.

Clickable periodic mesoporous organosilicas: synthesis, click reactions, and adsorption of antibiotics.

Pharmaceutical antibiotics are not easily removed from water by conventional water-treatment technologies and have been recognized as new emerging pollutants. Herein, we report the synthesis of clickable azido periodic mesoporous organosilicas (PMOs) and their use as adsorbents for the adsorption of antibiotics. Ethane-bridged PMOs, functionalized with azido groups at different densities, were synthesized by the co-condensation of 1,2-bis(trimethoxysilyl)ethane (BTME) and 3-azidopropyltrimethoxysilane (AzPTMS), in the presence of nonionic-surfactant triblock-copolymer P123, in an acidic medium. Four different alkynes were conjugated to azide-terminated PMOs by means of an efficient click reaction. The clicked PMOs showed improved adsorption capacity (241 µg g(-1)) for antibiotics (ciprofloxacin hydrochloride) compared with azido-functionalized PMOs because of the enhanced π-π stacking interactions. These results indicate that click reactions can introduce multifunctional groups onto PMOs, thus demonstrating the great potential of PMOs for environmental applications.

Clickable SBA-15 to screen functional groups for adsorption of antibiotics.

Pharmaceutical antibiotics, as emerging contaminants, are usually composed of several functional groups that endow them with the ability to interact with adsorbents through different interactions. This makes the preparation of adsorbents tedious and time-consuming to screen appropriate functionalized materials. Herein, we describe the synthesis of clickable SBA-15 and demonstrate its feasibility as a screening material for the adsorption of antibiotics based on similar adsorption trends on materials with similar functional groups obtained by a click reaction and cocondensation/grafting methods.

Surface-passivated SBA-15-supported gold nanoparticles: highly improved catalytic activity and selectivity toward hydrophobic substrates.

Silanol groups on a silica surface affect the activity of immobilized catalysts because they can influence the hydrophilicity/hydrophobicity, matter transfer, or even transition state in a catalytic reaction. Previously, these silanol groups have usually been passivated by using surface-passivation reagents, such as alkoxysilanes, bis-silylamine reagents, chlorosilanes, etc., and surface passivation has typically been found in mesoporous-silicas-supported molecular catalysts and heteroatomic catalysts. However, this property has rarely been reported in mesoporous-silicas-supported metal-nanoparticle catalysts. Herein, we prepared an almost-superhydrophobic SBA-15-supported gold-nanoparticle catalyst by using surface passivation, in which the catalytic activity increased more than 14 times for the reduction of nitrobenzene compared with non-passivated SBA-15. In addition, this catalyst can selectively catalyze hydrophobic molecules under our experimental conditions, owing to its high (almost superhydrophobic) hydrophobic properties.

Preparation of molecularly imprinted polymer nanoparticles for selective removal of fluoroquinolone antibiotics in aqueous solution.

In this study, novel molecularly imprinted polymer nanoparticles (nanoMCN@MIPs) were prepared by covalent grafting of ofloxacin-imprinted polymer onto the surface of mesoporous carbon nanoparticles (MCNs). SEM analyses indicated that the prepared nanoMCN@MIPs were almost uniform, and their geometrical mean diameter was about 230 nm. The sorption behaviors of the nanoMCN@MIPs including sorption kinetics and isotherms, effect of pH, ionic strength, and cross-reactivity were investigated in detail. The adsorption capacity of the nanoparticles for ofloxacin was 40.98 mg/g, with a selectivity factor of 2.6 compared to the nonimprinted polymer nanoparticles (nanoMCN@NIPs). The feasibility of removing fluoroquinolone antibiotics (FQs) from environmental waters with the nanoMCN@MIPs was demonstrated using sea water spiked with six typical FQs (ofloxacin, gatifloxacin, balofloxcacin, enrofloxacin, norfloxacin and sarafloxacin). The nanoMCN@MIPs could be reused at least five times with removal efficiency more than 90% except for norfloxacin.

Acid controlled diastereoselectivity in asymmetric aldol reaction of cycloketones with aldehydes using enamine-based organocatalysts.

The example of syn-aldol reaction of cyclohexanone to aldehyde was demonstrated based on chiral diamine organocatalysts and it was realized either by increasing the molecular size of acid additives or by introducing a hydrogen-bond donor into acid additives.

Enhancement of catalytic performance in asymmetric transfer hydrogenation by microenvironment engineering of the nanocage.

Ru-TsDPEN confined in the nanocage with an amphiphilic microenvironment can be ten times more active than that with a hydrophobic one in the transfer hydrogenation of acetophenone in HCOONa-H(2)O, which is mainly due to the enhanced diffusion rates of reactants during the catalytic process.

Chirally functionalized hollow nanospheres containing L-prolinamide: synthesis and asymmetric catalysis.

Chirally functionalized hollow nanospheres with different surface properties were successfully synthesized by co-condensation of (2S,1'R,2'R)-N-tert-butyloxycarbonylpyrrolidine-2-carboxylic acid [2'-(4-trimethoxysilylbenzylamide)cyclohexyl] amide with 1,2-bis(trimethoxysilyl)ethane or tetramethoxysilane using F127 (EO(106)PO(70)EO(106)) as surfactant in water. The TEM and N(2) sorption characterizations show that the particle size of the hollow nanosphere is 15-21 nm with a core diameter of 10-16 nm. These L-prolinamide-functionalized hollow nanospheres are highly efficient solid catalysts for the direct asymmetric aldol reaction between cyclohexanone and aromatic aldehydes. It was found that the addition of water in the reaction system not only enhanced the catalytic activity but also increased the enantioselectivity, which is probably due to the enhanced hydrogen bond between the amide oxygen atom and the hydroxyl group of water. Moreover, the catalytic activity increases sharply as the surface hydrophobicity of the hollow nanospheres increases. These hollow nanospheres are quite stable and can be reused with almost the same enantioselectivity and only a slight decrease in catalytic activity.