Synthesis of 1,3,5-Tris(phenylamino) Benzene Derivatives and Experimental and Theoretical Investigations of Their Antioxidation Mechanism

1,3,5-Tris­(phenylamino) benzene and a series of its substitution derivatives were synthesized. The structure of the as-synthesized products was confirmed by nuclear magnetic resonance spectroscopy and high resolution mass spectra. Moreover, the antioxidation behavior of 1,3,5-tris­(phenylamino) benzene and its substitution derivatives as antioxidants in several ester oils was evaluated by a rotary oxygen bomb test and pressurized differential scanning calorimetry, while theoretical calculations were conducted to examine their antioxidation mechanism. It was found that 1,3,5-tris­(phenylamino) benzene exhibits better antioxidation ability at elevated temperature (150 and 210 °C) than commonly used commercial antioxidant diphenylamine. In the meantime, the substitution groups exhibit significant effects on the antioxidation behavior of 1,3,5-tris­(phenylamino) benzene and its derivatives. This is because the substituents result in changes in the molecular structure and electronic effect of the as-synthesized products, thereby causing s change in their antioxidation behavior

The trend of overall obesity and abdominal obesity in three curves with an increase in age strata.

<p>There was no significant difference in obesity rates between users of calcium supplements and non-users of calcium supplements at each age stratum. Overall obesity, BMI ≥28 kg/m²; abdominal obesity І, WC ≥85 cm for men or WC ≥80 cm for women; abdominal obesity П, WHR ≥0.90 for men or WHR ≥0.85 for women.</p

Associations between time of calcium supplement use and obesity after multivariable adjustment.

<p>Overall obesity, BMI ≥28 kg/m²; Abdominal obesity І, WC ≥85 cm for men or WC ≥80 cm for women; Abdominal obesity П, WHR ≥0.90 for men or WHR ≥0.85 for women.</p><p>Multivariate analysis adjusted for age, physical activity level, energy intake, smoking, alcohol use, dietary calcium intake.</p

Standardized regression coefficient from the linear regression model.^Δ

<p>*<i>P<</i>0.05.</p><p>**<i>P</i><0.01.</p><p>***<i>P</i><0.001.</p><p>Δ Analysis adjusted for age, physical activity level, energy intake, smoking, alcohol use.</p

Associations between dietary calcium (quartile) and use of calcium supplements and obesity.

<p>Overall obesity, BMI ≥28 kg/m²; Abdominal obesity І, WC ≥85 cm for men or WC ≥80 cm for women; Abdominal obesity П, WHR ≥0.90 for men or WHR ≥0.85 for women.</p><p>Multivariate analysis adjusted for age, physical activity level, energy intake, smoking and alcohol use.</p><p>*<i>P<0.05.</i></p><p>**<i>P<0.01.</i></p><p>***<i>P<0.001.</i></p

The frequency distribution of responses on calcium supplement use in a Chinese population during 1999–2008.

<p>The frequency distribution of responses on calcium supplement use in a Chinese population during 1999–2008.</p

Characteristics of subjects, values are mean ± SD or n (%).

<p>Characteristics of subjects, values are mean ± SD or n (%).</p

Improvement of Mechanical Strength and Fatigue Resistance of Double Network Hydrogels by Ionic Coordination Interactions

Double network hydrogels (DN gels) are considered as one of the toughest soft materials. However, conventional chemically linked DN gels often lack high self-recovery and fatigue resistance properties due to permanent damage of covalent bonds upon deformation. Current strategies to improve self-recovery and fatigue resistance properties of tough DN gels mainly focus on the manipulation of the first network structure. In this work, we proposed a new design strategy to synthesize a new type of Agar/PAMAAc-Fe³⁺ DN gels, consisting of an agar gel as the first physical network and a PAMAAc-Fe³⁺ gel as the second chemical–physical network. By introducing Fe³⁺ ions into the second network to form strong coordination interactions, at optimal conditions, Agar/PAMAAc-Fe³⁺ DN gels can achieve extremely high mechanical properties (σ_<i>f</i> of ∼8 MPa, <i>E</i> of ∼8.8 MPa, and <i>W</i> of ∼16.7 MJ/m³), fast self-recovery (∼50% toughness recovery after 1 min of resting), and good fatigue resistance compared to properties of cyclic loadings by simply controlling acrylic acid (AAc) content in the second network. The high toughness and fast recovery of Agar/PAMAAc-Fe³⁺ DN gel is mainly attributed to energy dissipation through reversible noncovalent bonds in both networks (i.e., hydrogen bonds in the agar network and Fe³⁺ coordination interactions in the PAMAAc network). The time-dependent recovery of Agar/PAMAAc-Fe³⁺ gels at room temperature and the absence of recovery in Agar/PAMAAc gels also confirm the important role of Fe³⁺ coordination interactions in mechanical strength, self-recovery, and fatigue resistance of DN gels. Different mechanistic models were proposed to elucidate the mechanical behaviors of different agar-based DN gels. Our results offer a new design strategy to improve strength, self-recovery, and fatigue resistance of DN gels by controlling the structures and interactions in the second network. We hope that this work will provide an alterative view for the design of tough hydrogels with desirable properties