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In this study, the homopolymerization of 2,2‐dimethyltrimethylene carbonate (DTC) and its copolymerizations with e‐caprolactone (CL) were carried out in detail using the isothiourea‐based Lewis pairs comprised 2,3,6,7‐tetrahydro‐5H‐thiazolo(3,2‐a)pyrimidine and magnesium halides (MgX₂) with benzyl alcohol (BnOH) as the initiator. The copolymerization of DTC and CL via one‐pot addition produced randomly sequenced copolymers. On the other hand, a well‐defined linear poly(e‐caprolactone)–block–poly(2,2‐dimethyltrimethylene carbonate) (PCL‐b‐PDTC) diblock copolymer was prepared by simple sequential ring‐opening polymerization of CL and DTC. In addition, poly(ω‐pentadecalactone)–block–PDTC diblock copolymer was successfully prepared by the same strategy. Moreover, PDTC–poly(ethylene glycol) (PEG)–PDTC triblock copolymer was synthesized in the presence of PEG 2000. The effects of different polymerization conditions on the polymerization reactions have been systematically discussed. The resulting polymers were characterized by the ¹H and ¹³C NMR spectra, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐ToF MS). The block copolyester structures were confirmed by the ¹³C NMR spectroscopy and DSC characterizations. These results indicated that the supposed mechanism was a dual catalytic mechanism. The proposed mechanism involved activation of the monomer via coordination to the MgX₂, and the initiator alcohol was deprotonated by base. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2349–2355

Objectives To perform a systematic review and meta-analysis on the effects of audiovisual distraction on reducing dental anxiety in children during dental treatment under local anesthesia. Methods The authors identified eligible reports published through August 2017 by searching PubMed, EMBASE, and Cochrane Central Register of Controlled Trials. Clinical trials that reported the effects of audiovisual distraction on children's physiological measures, self-reports, and behavior rating scales during dental treatment met the minimum inclusion requirements. The authors extracted data and performed a meta-analysis of appropriate articles. Results Nine eligible trials were included and qualitatively analyzed; some of these trials were also quantitatively analyzed. Among the physiological measures, heart rate or pulse rate was significantly lower (p = .01) in children subjected to audiovisual distraction during dental treatment under local anesthesia than in those who were not; a significant difference in oxygen saturation was not observed. The majority of the studies using self-reports and behavior rating scales suggested that audiovisual distraction was beneficial in reducing anxiety perception and improving children's cooperation during dental treatment. Conclusion The audiovisual distraction approach effectively reduces dental anxiety among children. Therefore, we suggest the use of audiovisual distraction when children need dental treatment under local anesthesia.

Tetraphenylethylene (TPE) foldamers with double hairpin-turn linkers showing an aggregation-induced emission (AIE) effect have been synthesized for the first time. A crystal structure of a foldamer-TNT complex has been obtained, enabling unprecedented direct observation of the interactions between TNT molecules and the chromophores of the foldamer. Instead of π-π stacking interactions, which have often been considered to be the key mechanism in the binding of TNT by chromophoric receptors, strong n-π interactions between the nitro groups of TNT and the aromatic rings of the foldamer have been found. Exceptionally, by addition of 1 % NaF to a suspension of the foldamer in H2 O/THF (95:5), the fluorescence quenching efficiency by TNT vapor significantly increased from about 20 % to more than 90 %. Even after diluting TNT-saturated air at 25 °C by a factor of 2×104 , an obvious quenching response was observed, indicating that ultratrace TNT vapor (down to 3.4 fg per mL of air) could be detected.

To validate the Pain Resilience Scale (PRS) for use in Chinese patients with temporomandibular disorders (TMD) pain. According to international guidelines, the original PRS was first translated and cross-culturally adapted to formulate the Chinese version of PRS (PRS-C). A total of 152 patients with TMD pain were recruited to complete series of questionnaires. Reliability of the PRS-C was investigated using internal consistency and test-retest reliability. Validity of the PRS-C was calculated using cross-cultural validity and convergent validity. Cross-cultural validity was evaluated by examining the confirmatory factor analysis (CFA). And convergent validity was examined through correlating the PRS-C scores with scores of 2 commonly used pain-related measures (the Connor-Davidson Resilience Scale [CD-RISC] and the Tampa Scale for Kinesiophobia for Temporomandibular Disorders [TSK-TMD]). The PRS-C had a high internal consistency (Cronbach's alpha = 0.92) and good test-retest reliability (intra-class correlation coefficient [ICC] = 0.81). The CFA supported a 2-factor model for the PRS-C with acceptable fit to the data. The fit indices were chi-square/DF = 2.21, GFI = 0.91, TLI = 0.97, CFI = 0.98 and RMSEA = 0.08. As regards convergent validity, the PRS-C evidenced moderate-to-good relationships with the CD-RISC and the TSK-TMD. The PRS-C shows good psychometric properties and could be considered as a reliable and valid measure to evaluate pain-related resilience in patients with TMD pain.

Three new metal coordination complexes, namely [Co(BPY)2(H2O)2](BPY)(BS)2(H2O)4 (1), [Co(BPY)2(H2O)4](ABS)2(H2O)2 (2) and [Co(BPY)(H2O)4](MBS)2 (3) (BPY = 4,4′-bipyridine, BS = phenylsulfonic acid, ABS = p-aminobenzenesulfonic acid, MBS = p-methylbenzenesulfonic acid), were obtained under hydrothermal conditions. Complexes 1, 2, 3 were structurally characterized using single-crystal X-ray diffraction and infrared spectroscopy. All of them display low-dimensional motifs: complex 1 displays a two-dimensional structure; and complexes 2 and 3 exhibit a one-dimensional tape structure. Through strong intermolecular hydrogen bonding interactions and weak packing interactions, all of them further stack to generate a three-dimensional supramolecular architecture. Catalysts 1, 2, 3 were involved in the green synthesis of a variety of 3,4-dihydropyrimidin-2(1H)-ones under solvent-free conditions through Biginelli reactions. The corresponding catalytic product was obtained in quantitative yields (99%) under eco-friendly synthesis conditions for the variety of reactions. Catalysts 1, 2, 3 exhibit excellent efficiency for the desired product, and their catalytic performance shows the following order: 2 > 1 ≈ 3, which can be ascribed to the hydrophobic interactions of different phenylsulfonate groups. The catalytic performance for the Biginelli reaction is not only dependent on the selected solvents, but also inversely proportional to the polarities of the solvents. Copyright © 2016 John Wiley & Sons, Ltd.

In this study, a screening and confirmation method for the determination of l-hydroxyproline (Hyp) as a target compound in milk and dairy products using high-performance liquid chromatography with tandem mass spectrometry was developed. The samples were lyophilized after acidic hydrolysis, followed by cleanup with graphitized carbon black to remove pigments. Hyp was separated by a hydrophilic interaction chromatographic column and analyzed by high-performance liquid chromatography with tandem mass spectrometry working with multiple reaction monitoring mode using an electrospray ionization interface in a positive-ion mode. Average recoveries in spiked milk and dairy products ranged from 68.0 to 101.1% with relative standard deviations between 2.0 and 11.7% (n = 7). A reagent-matched standard calibration curve was used for quantification of Hyp, with linear correlation coefficient (R(2)) > 0.99 in the concentration range of 0.1-100 μg/mL. The LOQs were from 0.25 to 5 mg/kg, which were usually sufficient to verify the Hyp in samples. The confirmation concentration of Hyp ranged from 10 to 50 mg/kg.

The aim of this study was to evaluate the reliability and the validity of the Chinese version of the Dentine Hypersensitivity Experience Questionnaire (DHEQ). After translation and cross-cultural adaptation following international guidelines, 110 patients with dentine hypersensitivity were recruited to complete the questionnaire. The reliability of the Chinese version of the DHEQ was evaluated using internal consistency and test-retest methods. Construct validity was determined based on factor analysis, discriminative validity (by comparing the subscale scores difference in the degree of sensitivity being investigated), and convergent validity (by analyzing the correlation between DHEQ subscale scores and the global rating of oral health question). Cronbach's alpha value (internal reliability) for the total DHEQ score was 0.95 and the intraclass correlation coefficient (ICC) value (test-retest reliability) was 0.85. Construct validity was determined by factor analysis, extracting eight factors, accounting for 74% of the variance. All items had factor loadings of >0.40. In addition, the Chinese version of the DHEQ was found to be valid for distinguishing patients with varying degrees of dentine hypersensitivity. In terms of convergent validity, the impact scale was significantly highly correlated to the global oral health rating. The results suggest that the Chinese version of the DHEQ has satisfactory psychometric properties and is applicable for patients with dentine hypersensitivity in China.