A MgCl 2 -supported catalyst containing diisobutyl phthalate (DIBP) and 2,4-pentadiol dibenzoate (PDDB) as internal donors was prepared. Propylene polymerizations were carried out using the catalyst in the absence or presence of an external donor. The resulting polymers were characterized by 13 C-NMR, crystallization analysis fraction (CRYSTAF) and gel permeation chromatography (GPC). The performance of the catalyst was compared with that of other catalysts containing donor-free, DIBP and PDDB as internal donors respectively. The results demonstrated that the catalyst containing mixed internal donors not only had high activity and stereospecificity but also produced the polymer with relatively broad molecular weight distribution and the highest [mmmm] value. 13C-NMR analysis results indicated that strongly coordinating donors gave more stereoregular polymers, which was further confirmed by CRYSTAF data. The effects of mixed internal donors on the catalyst properties were discussed systematically.

A new sulfated chitosan superplasticizer (SCS) was synthesized by sulfation chitosan. The chemical structure and molecular weight of SCS were characterized by FTIR and gel permeation chromatography (GPC). The application performances of SCS in cement paste and concrete were investigated in the views of fluidity, slump, setting time, porosity as well as compressive strength. The results indicated that the SCS has better applied performance compared with polycarboxylate superplasticizer (PCs). A notable feature is that SCS has better maintenance for cement paste fluidity and concrete slump. The action mechanism behind this behavior was further revealed by zeta-potential and adsorption amount. Meanwhile, SCS comes from renewable source and has biodegradability. This research work provides not only a new superplasticizer but also a method for preparing superplasticizer from the renewable biopolymer.

Purpose To investigate the factors influencing and long-term effects of manual myotomy (MM) occurring during physical therapy for congenital muscular torticollis (CMT). Methods We retrospectively collected the clinical data of children with CMT receiving physical treatment between 2008 and 2018. The children were divided into MM and NMM groups according to whether MM occurred during treatment. Clinical data and outcome indicators (craniofacial asymmetry parameters and Cheng–Tang rating score) were compared. Results The MM group had a significantly higher total Cheng–Tang rating score than the NMM group (P < 0.05). Age at initial physiotherapy session was the risk factor for MM during physiotherapy. Conclusion Children with CMT developing MM during physiotherapy generally have a good outcome, although we do not recommend MM as a goal of treatment. Physiotherapists should understand this phenomenon, assess relevant factors to predict risk, and carefully observe treatment to prevent possible complications.