Average daily video screen time for 1 week for left-behind children aged 3 to 6 years.

Average daily video screen time for 1 week for left-behind children aged 3 to 6 years.</p

Multiple regression analysis of screen time and gross motor movement among left-behind children aged 3 to 6 years.

Multiple regression analysis of screen time and gross motor movement among left-behind children aged 3 to 6 years.</p

Aqueous RAFT Polymerization of Acrylonitrile

Controlled radical polymerization of acrylonitrile (AN) in concentrated aqueous solutions of sodium thiocyanate (NaSCN, 50 wt %) and zinc chloride (ZnCl₂, 60 wt %) is reported. Reversible addition–fragmentation chain transfer (RAFT) polymerization was successfully accomplished with 4-cyano-4-(phenyl­carbono­thioylthio)­pentanoic acid (CPAD) as a chain transfer agent (CTA) and AIBN as a radical initiator at 65 °C. First-order linear kinetic plots were observed in aqueous NaSCN with molecular weights (MW) between 3000 and 60 000 and relatively narrow molecular weight distributions (<i>M</i>_w/<i>M</i>_n = 1.2–1.4). Chain extension of the synthesized PAN macroinitiator with AN in aqueous NaSCN showed a clear shift in MWs which indicated high retention of chain end functionality. Furthermore, RAFT polymerization of AN in aqueous ZnCl₂ (60 wt %) was conducted with CPAD and 2,2′-azobis­(4-methoxy-2,4-dimethyl­valeronitrile) (V-70) as radical initiator at 30 °C. This system also exhibited linear kinetics and produced PAN with <i>M</i>_n = 13 300 but slightly higher dispersity (<i>M</i>_w/<i>M</i>_n = 1.38)

Gross motor movement characteristics of left-behind children aged 3 to 6 years.

Gross motor movement characteristics of left-behind children aged 3 to 6 years.</p

Analysis of the correlation between gross motor movement and screen time among left-behind children aged 3 to 6 years.

Analysis of the correlation between gross motor movement and screen time among left-behind children aged 3 to 6 years.</p

Study of the Microcharacter of Ultrastable Aqueous Foam Stabilized by a Kind of Flexible Connecting Bipolar-Headed Surfactant with Existence of Magnesium Ion

In this paper, ultrastable aqueous foam stabilized by a kind of flexible connecting bipolar-headed surfactant alkyl polyoxyethylene sulfate (AE₃S) with coexisting Mg²⁺ was reported. Detailed molecular behaviors of AE₃S in foam film with coexisting divalent cationic Ca²⁺ or Mg²⁺ were investigated by molecular dynamic simulation, comparing with the traditional surfactant sodium dodecyl sulfate (SDS), to find out how the microcharacter and array behavior of molecules in the foam film determined by molecular interaction effect the foam stability. It was found that the ultrastable foam film obtained by the cooperation of magnesium ions and AE₃S was driven from two aspects: one is the favorable arrangement of surfactant molecules, and the other is the increase of capacity of foam films for resolutely holding water molecules deduced by a dipolar pair formed by the flexible connecting head groups of AE₃S and hydrated Mg²⁺ via intermolecular coactions, both related to the presence of magnesium ions. Foam lamella stability measurement and foam decay method were both used to evaluate the stability of foam. Fourier transform infrared (FT-IR) was used to detect the composition variation of foam film in the drainage process; the vibration peak of OH for water molecule shifted from the 3390 cm^–1 (being assigned to the bulk water integrated by hydrogen bonds) to 3685 cm^–1 (being assigned to the vibration of isolated water molecules) for the ultrastable foam film after complete drainage, which agreed very well with the molecular simulation results

Co-pyrolysis of E‑Waste Nonmetallic Residues with Biowastes

This work studied the copyrolysis of nonmetallic fractions from waste printed circuit boards (NMF-WPCB) with rice husk (RH). The chemical pretreatment integrated with pyrolysis was evaluated for copyrogasification valorization of e-waste plastics and biowastes for value-added fuel (e.g., syngas) production. The copyrolysis with cellulose-rich biomass can improve the NMF thermolysis efficiency, while the copyrolysis with lignin-rich biomass improved the activation energy. The copyrolysis NMF with RH can improve the fuel property and thermal conversion efficiency. Metals in the NMF were primarily removed by the acid leaching. Subsequently, the preloaded NaOH could react with the small-molecular bromine compounds (e.g., HBr/Br₂ releasing from the BFRs pyrolysis) to form more stable NaBr. Minerals (e.g., alkalis) in RH and NMF enhanced the Br stabilization in the char. In general, the syngas from the copyrolysis of PNMF with RH can be applied for fuels, while the char with lower contents of heavy metals is terminally disposed of by safely landfilling it

L'Athlète : journal hebdomadaire de tous les sports

01 mai 19251925/05/01 (N415)-1925/05/01.Appartient à l’ensemble documentaire : Aquit