The bidirectional relationship between peer relationships and bullying: Evidence from cross-lagged analyses among Chinese children.

BACKGROUND: In the digital age, bullying manifests in two distinct forms: traditional bullying and cyberbullying. Children's peer relationships are important predictors of bullying, and bullying in turn predicts peer relationships. However, few researchers have noted the bidirectional relationship between peer relationships and bullying. METHODS: The present study used a two-wave cross-lagged longitudinal design to fill this gap. The potential sex differences were also examined in this relationship. The sample consisted of 527 Chinese children aged 8 to 12 years (M = 9.69, SD = .96; 53.5% female). Participants completed peer nominations for peer acceptance, peer rejection and social dominance, as well as self-reports of traditional bullying and cyberbullying. RESULTS: Results showed that peer rejection at the first time point (T1) significantly and positively predicted traditional bullying perpetration, cyberbullying perpetration and cyberbullying victimization at the second time point (T2). Traditional bullying victimization at T1 significantly and negatively predicted peer acceptance and social dominance at T2. The results also revealed significant male and female differences. For instance, among boys, peer acceptance at T1 significantly and negatively predicted cyberbullying victimization at T2. In contrast, this relationship was not observed among girls. The present findings have important implications for understanding the cyclical relationship between peer relationships and bullying and providing practical guidance for improving peer relationships and reducing bullying.

Life Stress and Cyberbullying: Examining the Mediating Roles of Expressive Suppression and Online Disinhibition.

Life stress is a significant predictor of cyberbullying. However, previous studies have not investigated the roles of emotional and cognitive characteristics, such as expressive suppression and online disinhibition, in explaining the associations between life stress and cyberbullying perpetration/victimization. To fill this gap, a two-wave longitudinal design was used to investigate these two mediating variables as the underlying mechanisms among adolescents after controlling for possible covariates. A total of 724 Chinese adolescents (female: 41.2%) aged 12 to 16 years old (M = 13.36, SD = 0.77) participated in this survey. They completed self-report questionnaires on life stress, expressive suppression, online disinhibition (including benign and toxic disinhibition), cyberbullying perpetration, and cyberbullying victimization. The survey was conducted in two waves, six months apart. The correlational analyses showed that life stress was positively associated with cyberbullying perpetration/victimization cross-sectionally and longitudinally. After controlling other variables, life stress did not predict cyberbullying perpetration cross-sectionally or longitudinally, but cross-sectionally predicted cyberbullying victimization. The results only revealed the significant mediation effects of expressive suppression and online disinhibition at the first time point. Specifically, toxic disinhibition mediated the relationship between life stress and cyberbullying perpetration/victimization, and benign disinhibition mediated the relationship between life stress and cyberbullying victimization. In addition, life stress cross-sectionally and positively predicted cyberbullying victimization through the serial mediating roles of expressive suppression and benign disinhibition. The results of the multi-group analysis showed that there was no significant difference in the hypothesized model for the male and female groups. This study reveals how life stress is related to cyberbullying perpetration/victimization. Reducing expressive suppression and online disinhibition may be effective in preventing cyberbullying among adolescents.

Molecularly Imprinted Polymer Nanospheres with Hydrophilic Shells for Efficient Molecular Recognition of Heterocyclic Aromatic Amines in Aqueous Solution.

Heterocyclic aromatic amine molecularly imprinted polymer nanospheres with surface-bound dithioester groups (haa-MIP) were firstly synthesized via reversible addition-fragmentation chain transfer (RAFT) precipitation polymerization. Then, a series of core-shell structural heterocyclic aromatic amine molecularly imprinted polymer nanospheres with hydrophilic shells (MIP-HSs) were subsequently prepared by grafting the hydrophilic shells on the surface of haa-MIP via on-particle RAFT polymerization of 2-hydroxyethyl methacrylate (HEMA), itaconic acid (IA), and diethylaminoethyl methacrylate (DEAEMA). The haa-MIP nanospheres showed high affinity and specific recognition toward harmine and its structural analogs in organic solution of acetonitrile, but lost the specific binding ability in aqueous solution. However, after the grafting of the hydrophilic shells on the haa-MIP particles, the surface hydrophilicity and water dispersion stability of the polymer particles of MIP-HSs greatly improved. The binding of harmine by MIP-HSs with hydrophilic shells in aqueous solutions is about two times higher than that of NIP-HSs, showing an efficient molecular recognition of heterocyclic aromatic amines in aqueous solution. The effect of hydrophilic shell structure on the molecular recognition property of MIP-HSs was further compared. MIP-PIA with carboxyl groups containing hydrophilic shells showed the highest selective molecular recognition ability to heterocyclic aromatic amines in aqueous solution.

Preparation of Functionalized Zr-Based MOFs and MOFs/GO for Efficient Removal of 1,3-Butadiene from Cigarette Smoke.

Removal of 1,3-butadiene from cigarette smoke plays an important role in human health and environmental protection. Herein, a series of UiO-66 X% containing different ratios of the -NH2 group was synthesized via the solvothermal method by using terephthalic acid (H2BDC) and 2-aminoterephthalic acid (NH2-BDC) as ligands. Using GO as support, a series of UiO-66-NH2/GO Y% were prepared by controlling the ratio of UiO-66-NH2 and GO. The effects of -NH2 and GO contents on the structure and composition of MOFs were investigated. Finally, the different -NH2 contents of UiO-66 X% and the different GO contents of UiO-66-NH2/GO Y% were applied in 1,3-butadiene removal from cigarette smoke. The results showed that UiO-66 X% with the higher contents of -NH2 showed a higher rate of 1,3-butadiene removal, and UiO-66-NH2/GO Y% with the GO contents of 5% showed the highest removal rate of about 33.85%, which was 25.54% higher than that of activated carbon. In addition, the saturation capacity of the adsorbent materials for 1,3-butadiene was as high as 210.01-239.54 mg/g, showing great potential in reducing harmful components in cigarette smoke and environmental protection.

Robust, comprehensive, sensitive analysis of flavour additives with carboxyl and hydroxyl groups in cigarette smoke combining silylation and gas chromatography-tandem mass spectrometry with an improved backflushing system.

Flavour additives with carboxyl and hydroxyl groups (FACHs), the key ingredients in characteristic flavours, are frequently detected in cigarette smoke. They are attracting increasing attention in regulating the flavour additives used in tobacco to curb youth tobacco use and prevent the use of additives that are harmful. In this study, a highly robust, sensitive, and precise method based on silylation and GC-MS/MS with an improved backflushing system was developed for the simultaneous analysis of 171 FACHs in cigarette smoke. Silylation has been shown to have advantages in terms of high selectivity and sensitivity to chemicals with carboxyl and hydroxyl groups, especially when combined with GC-MS/MS. The extraction and silylation conditions were optimised. Dichloromethane was used as the extraction agent. BSTFA in combination with 1% TMCS and 0.2% TMSI was selected as silylating agent for high silylation efficiency, particularly for hindered analytes. The method has been validated. The limit of detection (LOD) ranged from 0.6 to 332.3 ng/mL. 91.1% out of the analytes in QC samples had precisions lower than 10% during one month run. The improved backflushing system with a fused silica splitter was shown to be crucial in the excellent long-term robustness of the method. The developed method was used to determine flavour additives in 270 practical cigarette smoke samples with reliable results. A total of 154 FACHs were identified with wide-range levels among different cigarette brands.

Preparation of PolyHIPE Scaffolds for 3D Cell Culture and the Application in Cytotoxicity Evaluation of Cigarette Smoke.

Polystyrene-based polyHIPE (polymerized high internal phase emulsion) materials were prepared by the copolymerization of styrene and divinylbenzene in the continuous phase of a HIPE. The resultant polyHIPE materials were found to have an open-cellular morphology and high porosity, and the polyHIPE structure could be well adjusted by varying the water/oil (W/O) ratio and the amount of emulsifier in the HIPE. Cell culture results showed that the resultant polyHIPE materials, which exhibited larger voids and connected windows as well as high porosity, could promote cell proliferation on the 3D scaffold. A 3D cell cytotoxicity evaluation system was constructed with the polystyrene-based polyHIPE materials as scaffolds and the cigarette smoke cytotoxicity was evaluated. Results showed that the smoke cytotoxicity against A549 cells is much lower in the 3D cell platform compared to the traditional 2D system, showing the great potential of the polyHIPE scaffolds for 3D cell culture and the cytotoxic evaluation of cigarette smoke.

Investigation of the chromatographic regulation properties of benzyl groups attached to bridging nitrogen atoms in a calixtriazine-bonded stationary phase.

Two reversed-phase/anion-exchange mixed-mode stationary phases for high-performance liquid chromatography using calixtriazines as chromatographic ligands were investigated with Tanaka test solutes, monosubstituted benzenes, aromatic positional isomers, and inorganic anions. Calixtriazine as a chromatographic ligand has been reported previously, but the benzylated nitrogen-bridged calixtriazine-bonded silica gel reported in this study is new. The experimental data showed that the calixtriazine platform is a unique chromatographic selector because its multiple active sites are available for different solutes and its chromatographic selectivity could be tuned by introducing substituent on the bridging nitrogen atoms present in the calixtriazine matrix. The synergistic effects of aromatic rings, nitrogen atoms, benzyl groups, and tunable cavity in the host molecule influenced the separation selectivity by multiple retention mechanisms. Such hybrid stationary phases provide more versatility and have great potential in the analysis of complex samples. Moreover, the synthetic protocols presented herein may provide an alternative understanding on macrocyclic host-guest chemistry, leading to new and selective separation media.

Simultaneous quantification of ten Amadori compounds in tobacco using liquid chromatography with tandem mass spectrometry.

Amadori compounds are aroma precursors formed in the initial phase of the Maillard reaction. Based on their similar structures, simultaneous quantification of more than six Amadori compounds in tobacco has not been reported yet. In this study, a simple and rapid method was developed to simultaneously quantify ten Amadori compounds including the isomers of Fructose-isoleucine and Fructose-leucine in tobacco. The separation was performed on an Atlantis T3 column (2.1 × 250 mm, 5 µm) by gradient elution using acetonitrile and water as the mobile phases. The quantification method was systematically evaluated and proven to be sensitive and accurate. The linearity was good, with correlation coefficients of 0.9977-0.9999. The limits of detection and quantitation were 1.354-2.532 and 4.516-8.444 ng/mL, respectively. The recoveries were 84.0-119.6%, and the relative standard deviations were 1.33-5.40%. The method was used to analyze the changes in the amounts of ten Amadori compounds in tobacco before and after tobacco primary processing. The analysis shows that the Maillard reaction occurs during the short processing period.

Determination of nitroalkanes in mainstream cigarette smoke by heart-cutting multidimensional gas chromatography system coupled with mass spectrometry detection.

In this paper, heart-cutting two-dimensional GC/MS (GC-GC/MS) method in combination with a simple sample collection procedure was developed for the determination of 6 nitroalkanes in mainstream cigarette smoke. The method could remove large amounts of impurities on-line in the first polar column by heart-cuts and separate from the left interferences in a second mid-polar column. And the target compounds could be focused at the inlet of the second column by cryo-concentration. Compared to conventional GC/MS, GC-GC/MS achieved a lower noise level and sensitivity at least an order of magnitude higher. Furthermore, the GC-GC/MS method could avoid the false negative and false positive results that appeared in the compared conventional GC/MS analysis. By trapping the vapor phase of 20 cigarettes smoke, the LODs and LOQs of the nitroalkanes were 1.3 to 9.8 and 4.3 to 32.6ng/cigarette, respectively, and all linear correlation efficiencies were larger than 0.999. The validation results also indicate that the method has high accuracy (spiked recoveries between 84% and 102%) and good repeatability (RSD between 7.2% and 9.4%). The developed method was applied to analyze 1 Kentucky reference cigarette (3R4F) and 10 Chinese commercial brands of cigarettes. The research results indicated that nitromethane, nitroethane, 2-nitropropane and 1-nitro-n-pentane were detected in mainstream cigarette smoke, but 1-nitro-n-butane and 2-nitropropane, which were reported by one previous study, were not detected in all cigarette samples.

Oxidation of ethyl ether on borate glass: chemiluminescence, mechanism, and development of a sensitive gas sensor.

A gas sensor was developed by using the chemiluminescence (CL) emission from the oxidation of ethyl ether by oxygen in the air on the surface of borate glass. Theoretical calculation, together with experimental investigation, revealed the main CL reactions: ethyl ether is first oxidized to acetaldehyde and then to acetic acid, during which main luminous intermediates such as CH 3CO (*) are generated and emit light with a peak at 493 nm. At a reaction temperature of 245 degrees C, the overall maximal emission was found at around 460 nm, and the linear range of the CL intensity versus the concentration of ethyl ether was 0.12-51.7 microg mL (-1) ( R = 0.999, n = 7) with a limit of detection (3sigma) of 0.04 microg mL (-1). Interference from foreign substances including alcohol (methanol, ethanol and isopropanol), acetone, ethyl acetate, n-hexane, cyclohexane, dichloromethane, or ether ( n-butyl ether, tetrahydrofuran, propylene oxide, isopropyl ether and methyl tert-butyl ether) was not significant except a minimal signal from n-butyl ether (<2%). It is a simple, sensitive and selective gas sensor for the determination of trace ethyl ether.