A cucurbit[7]uril-based supramolecular fluorescent probe for the detection of metronidazole with high sensitivity and strong anti-interference capacity

We propose a new method for the selective detection of the antibiotic metronidazole (MNZ) using CB[7]-JAT (cucurbit[7]uril = CB[7] and JAT = jatrorrhizine) as a fluorescent probe, which is based on the competitive reaction between MNZ and JAT for the occupancy of the CB[7] cavity. The proposed method gives a good calibration curve in the concentration range of 0.38–60 μM, and the limit of detection for MNZ is 65 ng mL−1 with those obtained by the standard curve method. Moreover, the proposed method was successfully applied for the determination of MNZ in liquid milk. Most importantly, due to the high binding affinity between CB[7] and MNZ, the proposed method shows great anti-interference capacity to accurately detect MNZ in the presence of other antibiotics.

The Effects of Weapon Toys on Aggressive Behavior among Chinese Children: The Mediating Role of Aggressive Cognition

Background: The purpose of the study was to explore the relationships between exposure to weapon toys and aggressive behavior. Methods: The study sample included 104 six-year-old kindergarten children. Half of them were randomly assigned to play with weapon toys (experimental group) or non-weapon toys (control group). A Semantic Classification Task (SCT) and a Competitive Reaction Time Task (CRTT) were employed to measure aggressive cognition and aggressive behavior. A randomized controlled study was performed and a 2 x 2 (Toys, Gender) Analysis of Covariance (ANCOVA) statistical test was used to evaluate the effect of toys on aggressive cognition (reaction times to weapon pictures) and behavior (noise intensity setting), controlling for age. Mediation analysis was also conducted to test the mediating role of aggressive cognition in this effect.Results: Results indicated that playing with weapon toys increased aggressive cognition and aggressive behavior. Specifically, boys were more likely than girls to exhibit aggressive behavior in the weapon toys condition, though girls did exhibit aggressive cognition. Mediation analysis indicated that the weapon toy effect on aggressive behavior was partially mediated by aggressive cognition. Conclusions: The main findings of the study suggest that boys may be considered as the target group for aggression intervention and reduction in the context of weapon toys. Practitioners can take away the weapon toys to reduce aggressive cognition, so as to decrease children’s aggressive behavior.

Hydrogenation of alkynyl substituted aromatics over rhodium/silica

The cascade reactions of phenylacetylene to ethylcyclohexane and 1-phenyl-1-propyne to propylcyclohexane were studied individually, under deuterium and competitively at 343 K and 3 barg pressure over a Rh/silica catalyst. Both systems gave similar activation energies for alkyne hydrogenation (56 ± 4 kJ mol−1 for phenylacetylene and 50 ± 4 kJ mol−1 for 1-phenyl-1-propyne). Over fresh catalyst the order of reactivity was styrene > phenylacetylene ≫ ethylbenzene. Whereas with the cascade hydrogenation starting with phenylacetylene, styrene hydrogenated much slower phenylacetylene even once all the phenylacetylene was hydrogenated. The activity of ethylbenzene was also reduced in the cascade reaction and after styrene hydrogenation. These reductions in rate were likely due to carbon laydown from phenylacetylene and styrene. Similar behavior was observed with the 1-phenyl-1-propyne cascade. Deuterium experiments revealed similar positive KIEs for phenylacetylene (2.6) and 1-phenyl-1-propyne (2.1). Ethylbenzene hydrogenation/deuteration gave a KIE of 1.6 obtained after styrene hydrogenation in contrast to the inverse KIE of 0.4 found with ethylbenzene hydrogenation/deuteration over a fresh catalyst, indicating a change in rate determining step. Competitive hydrogenation between phenylacetylene and styrene reduced the rate of phenylacetylene hydrogenation but increased selectivity to ethylbenzene suggesting a change in the flux of sub-surface hydrogen. In the competitive reaction between 1-phenyl-1-propyne and propylbenzene, the rate of hydrogenation of 1-phenyl-1-propyne was increased and the rate of alkene isomerization was decreased, likely due to an increase in the hydrogen flux for hydrogenation and a decrease in the hydrogen species active in methylstyrene isomerization.

Bimetallic Pt-Co Nanoparticle Deposited on Alumina for Simultaneous CO and Toluene Oxidation in the Presence of Moisture

Carbon monoxide (CO) and hydrocarbons (HCs) generally have competitive adsorption on the active site of noble-metal nano-catalysts, thus developing an effective way to reduce the passivation of competitive reaction with each other is an urgent problem. In this study, we successfully synthesized transition metal-noble metal (Pt-M) alloys via introducing inexpensive metal elements (M = Ni, Co and Cu) into Pt particles and then deposited on alumina support to form Pt-based catalysts. Subsequently, we choose CO and toluene as polluting gases to evaluate the catalytic activities of Pt-M/Al2O3 catalysts. Introducing inexpensive metal elements (M = Ni, Co, and Cu) significantly changed the physicochemical properties and catalytic activities of these Pt-based catalysts. It can be found that the Pt-Co/Al2O3 catalyst exhibited outstanding catalytic activity for CO and toluene oxidation under mixed gas atmosphere, compared with other Pt-based catalysts, which is due to the higher dispersity, more surface adsorption oxygen, and well redox ability. Surprisingly, H2O could promote the catalytic activities for CO/toluene co-oxidation over the Pt-Co/Al2O3 catalyst. Thus, the present synthetic strategy not only opens an avenue towards the synthesis of noble metal-based catalysts, but also provides an excellent tolerance to H2O in the catalytic process.