硝酸甘油:祸兮福所倚,福兮祸所伏——舞台剧剧本

自1846年硝酸甘油被合成以来,人们一直把其当作炸药来使用。但由于硝酸甘油过于敏感,导致事故不断。为解决这一问题,诺贝尔尝试改良硝酸甘油,将硅藻土与硝酸甘油混合,降低了敏感度,达到安全使用炸药的目的。后来人们发现硝酸甘油还有缓解心绞痛的功能,便对其进行了深入研究。本文以剧本的形式向大众科普硝酸甘油的上述功能。     

Toughening hydrogels by immersing with oppositely charged polymers

A very simple yet novel strategy to significantly enhance the mechanical properties of hydrogels is reported. Poly(acrylic acid) (PAA) hydrogels with aligned macroporous channels are immersed in the aqueous solutions of poly(dimethyl diallyl ammonium chloride) (PDMDAAC). Strong electrostatic interactions are formed between the anionic PAA and cationic PDMDAAC chains. In the resultant PAA/PDMDAAC hybrid hydrogels, the mass ratio of PDMDAAC to PAA is about 0.2 and PDMDAAC is uniformly distributed throughout the gels. The mechanical properties of the formed hybrid hydrogels are largely enhanced in comparison with the original PAA hydrogels. The hybrid hydrogels exhibit high tensile strengths (0.38–1.73 MPa), elastic moduli (0.21–1.59 MPa) and toughness (up to 3.0 MJ/m³), about several to more than 10 times those of the corresponding PAA hydrogels. In addition, the PAA/PDMDAAC hydrogels also show excellent and very rapid shape recovery ability in both air and deionized water. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2432–2441     

Pseudopeptide‐Based Hydrogels Trapping Methylene Blue and Eosin Y

We present herein the preparation of four different hydrogels based on the pseudopeptide gelator Fmoc‐l ‐Phe‐d ‐Oxd‐OH (Fmoc=fluorenylmethyloxycarbonyl), either by changing the gelator concentration or adding graphene oxide (GO) to the water solution. The hydrogels have been analysed by rheological studies that demonstrated that pure hydrogels are slightly stronger compared to GO‐loaded hydrogels. Then the hydrogels efficiency to trap the cationic methylene blue (MB) and anionic eosin Y (EY) dyes has been analyzed. MB is efficiently trapped by both the pure hydrogel and the GO‐loaded hydrogel through π–π interactions and electrostatic interactions. In contrast, the removal of the anionic EY is achieved in less satisfactory yields, due to the unfavourable electrostatic interactions between the dye, the gelator and GO.     

Analytic Atomic Screening Parameters for Slater Type Orbitals

Screening parameters to be used in Slater Type Orbitals were obtained in analytic form. The values compared well with the numerical results given by Clementi and Roetti (after a laborious process of optimization) and with the phenomenological values of Jung and Gould. The analytic formulation is based on the splitting of the two-body operator 1/r_st as the sum of effective one-body operators.     

Influence of multiwall carbon nanotubes on morphological and structural changes during UV irradiation of syndiotactic polypropylene films

The effect of UV irradiation on the morphology and structure of syndiotactic polypropylene (sPP) is investigated both for pure films and those filled with multiwall carbon nanotubes (MWCNTs). UV treatment causes a structural reorganization of pure sPP films. It seems that the incorporation of MWCNTs has a strong stabilizing effect, with nanotubes acting as a limiter of the UV‐induced chain breakage, especially when a good dispersion of carbon nanotubes in the polymer is achieved. The incorporation of MWCNTs introduces a high concentration of defects in the crystal structure of sPP, which limits the UV‐induced growth of crystallites, and prevents the development and propagation of cracks caused by UV irradiation. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012