How can Nanohybrids Enhance Polyester/Sepiolite Nanocomposite Properties?

PCL/sepiolite (nano)composites are prepared by melt blending in a twin‐screw mini‐extruder, and PCL/sepiolite nanohybrids are synthesized by ROP of ε‐CL. The nanohybrids have been used as masterbatches and dispersed in a commercial PCL matrix. Composites with 3 wt.‐% nanofiller were prepared and characterized thermally, mechanically, and morphologically. Sepiolite addition has a profound effect on the mechanical properties of the PCL/sepiolite nanocomposites. Sepiolite disperses well in PCL, which leads to a significant increase in Young's modulus. The use of a PCL nanohybrid as masterbatch further improves the stiffness but also the toughness of the material in the elastic range.

     

Change of Distribution and Timing of Bite Force after Botulinum Toxin Type A Injection Evaluated by a Computerized Occlusion Analysis System

Purpose

The aim of this study was to determine the force distribution and pattern of mastication after injection of botulinum toxin type A (BTX-A) into both masseter muscles. The hypothesis to be tested was that the difference between right and left balance of occlusal force diminishes over time following BTX-A injection.

Materials and Methods

Fifteen patients were submitted to BTX-A injection therapy for subjective masseter hypertrophy. A total of 25 U of BTX-A (50 U in total) was injected into two points located 1 cm apart at the center of the lower one-third of both masseter muscles. All patients were examined using the T-Scan occlusion analysis system before and 4, 8, 12, and 24 weeks after BTX-A injection.

Results

A significant change in force balance was found between the right and left sides over time and the difference between the two sides decreased with the time post-injection, reaching a minimum at 12 weeks. Comparison of the force balance between the anterior and posterior occlusions revealed no significant difference at any of the time points. The occlusion and disclusion times (right and left sides) did not differ significantly with time since BTX-A injection.

Conclusion

A decline in the difference in the clenching force between the left and right sides was found with increasing time up to 12 weeks following BTX-A injection.     

Poly(N,N‐dimethylacrylamide)‐block‐Poly(L‐lysine) Hybrid Block Copolymers: Synthesis and Aqueous Solution Characterization

Four poly(N,N‐dimethylacrylamide)‐block‐poly(L ‐lysine) (PDMAM‐block‐PLL) hybrid diblock copolymers and two PLL homo‐polypeptides are prepared via ROP of ε‐trifluoroacetyl‐L ‐lysine N‐carboxyanhydride initiated by primary amino‐terminated PDMAM and n‐hexylamine respectively. The PLL blocks render the copolymers a multi‐responsive behavior in aqueous solution due to their conformational transitions from random coil to α‐helix with increasing pH, and from α‐helix to β‐sheet upon heating. The random coil‐to‐α‐helix transition is found to depend on the PLL length: the longer the peptide segment, the more readily the transition occurred. The same trend was observed for the α‐helix‐to‐β‐sheet transition, which was found to be inhibited for short polypeptides unless conjugated with the PDMAM block.

     

Synthesis of Functional Polydepsipeptides via Direct Ring‐Opening Polymerization and Post‐Polymerization Modification

This contribution explores different strategies for the synthesis of side chain functional polydepsipeptides. First, the ring‐opening polymerization of side chain functional morpholine‐2,5‐diones is revisited and the optimized reaction conditions used for the polymerization of (Z)‐L ‐Lys, (Boc)‐L ‐Lys and L ‐allylglycine based morpholine‐2,5‐diones. As a first approach towards side chain functional polydepsipeptides, the deprotection of poly(Glc‐alt‐(Z)‐L ‐Lys) and poly(Glc‐alt‐(Boc)‐L ‐Lys) is evaluated. Although under appropriate conditions, the side chain protecting groups can be quantitatively removed, the reaction conditions used here were found to lead to backbone degradation. As an alternative approach, the thiol‐ene post‐polymerization modification of poly(Glc‐alt‐allylglycine) is explored. Free radical addition of various ω‐functional thiols was found to proceed without backbone degradation and in several cases with quantitative allyl group conversion. The post‐polymerization modification strategy is attractive as it obviates the need for protecting group chemistry and facilitates the synthesis of diverse libraries of side chain functional polydepsipeptides.

     

Ring‐Opening Copolymerization of 2‐Aryl‐1‐methylenecyclopropanes with Carbon Monoxide Initiated by Pd–bpy Complexes

[PdCl(Me)(bpy)] and a mixture of the complex with cocatalysts; NaBARF (BARF = [B{C₆H₃(CF₃)₂‐3,5}₄]^?), NaBF₄, AgBARF, AgBF₄, and AgOTf, catalyze the copolymerization of 2‐phenyl‐1‐methylenecyclopropane with carbon monoxide to produce a new polyketone accompanied by ring opening of the monomer. ¹H and ¹³C{¹H} NMR spectra indicate that the polymers have two isomeric repeating units in which the phenyl substituents occupy different positions. The molecular weights of the polyketones formed by the reactions with a [Pd]/[cocatalyst]/[2‐phenyl‐1‐methyleneyclopropane] ratio of 1:3:70 are in the range of M _n = 13 100–86 000. The polymer obtained by the reaction promoted by [PdCl(Me)(bpy)]/MBARF, where M = Ag or Na, shows a narrow molecular weight distribution, M _w/M _n = 1.44 and 1.59, respectively. The catalysis is effective also for the ring‐opening copolymerization of 2‐aryl‐1‐methylenecyclopropanes bearing Me and F substituents on the phenyl ring. Isotope‐labeled experiments revealed the mechanism of the polymerization, which involves a 1,2‐insertion of the monomer into the Pd–acyl bond to produce a cyclopropylmethyl palladium intermediate, and subsequent β‐alkyl elimination to give the Pd–alkyl complex.

     

耳廓掀翻入路的显微解剖与临床应用

目的：报道耳外科新的手术入路的显微解剖与临床应用。方法：在38侧标本上对外耳血供进行解剖观察，设计了耳廓向下掀翻入路，应用于121例耳部疾患。结果：外耳血供来自颈外动脉的颞浅动脉和耳后动脉，其外侧面为颞浅动脉上、中、下耳支及耳后动脉耳廓支的穿支供应，背面为耳后动脉上、中、下耳支供应。经耳廓掀翻中耳乳突手术入路，手术野大，暴露好，未发生耳廓缺血坏死或感觉障碍。结论：耳廓掀翻是现代耳外科理想的手术进路。     

Controlled ROMP Synthesis of Ferrocene‐Containing Amphiphilic Dendronized Diblock Copolymers as Redox‐Controlled Polymer Carriers

Novel well‐defined redox‐responsive Ferrocene (Fc)‐containing amphiphilic dendronized diblock copolymers are synthesized by the ring‐opening metathesis polymerization technique using Grubbs’ third‐generation olefin metathesis catalyst as the initiator. These dendronized block copolymers can self‐assemble into spherical micelles in aqueous solution. The size of self‐assembled micelles can be modulated by the composition (namely, the ratio of hydrophobic and hydrophilic segments) and concentration of the dendronized copolymers. The obtained micelles show reversible redox‐controlled self‐assembly behaviors using FeCl₃ as oxidant and glutathione as reductant. Furthermore, the model molecule Rhodamine B is successfully loaded in these micelles, and the oxidation‐triggered controllable release is achieved by changing the type of oxidants (FeCl₃ and H₂O₂) and their concentrations. This is the first example of redox‐responsive micelles self‐assembled by novel amphiphilic dendronized Fc‐containing block copolymers, and the present micelles are visualized to be potential candidates in many fields, especially in stimuli‐responsive drug delivery systems.     

Synthesis and Characterization of Comb‐Like Copolymers Based on Poly(ε‐caprolactone) and Poly(α‐olefin)

Comb‐like copolymers based on a polyolefin backbone of poly(10‐undecene‐1‐ol) (PUol) with poly(ε‐caprolactone) (PCL) side chains are synthesized in two steps. After synthesis of PUol by metallocene‐catalyzed polymerization, the side‐chain hydroxyl functionalities of this polar polyolefin are used as an initiator for the ring‐opening polymerization (ROP) of ε‐caprolactone (CL). In this context, copolymers with different lengths of PCL grafts are prepared. The chemical structure and the composition of the synthesized copolymers are characterized by ¹H and ¹³C NMR spectroscopy. It is shown that the hydroxyl end groups of PUol act effectively as initiating sites for the CL ROP. Size‐exclusion chromatography (SEC) measurements confirm the absence of non‐attached PCL and the expected increase in molar mass after grafting. The thermal and decomposition behaviors are investigated by DSC and thermogravimetric analysis (TGA). The effect of the length of the PCL grafts on the crystallization behavior of the comb‐like copolymers is investigated by DSC and wide‐angle X‐ray scattering (WAXS).

     

腹蛇咬伤致心肌损害的护理

蝮蛇咬伤是江南地区常见的危及广大人民群众的外伤病证,其中心肌损害是其主要的并发症。我院外科是浙江省中医药治疗蛇伤重点专科,近年来,我们采用自制的蛇伤Ⅱ号,配合积极有效的辨证施护,在蝮蛇咬伤所致心肌损害的治疗中取得了较好的效果,现报告如下。     

Synthesis of PLLA‐MPEG Diblock Copolymers by Microwave‐Assisted Copolymerization of L‐Lactide and Methoxy Poly(ethylene glycol)

PLLA‐MPEG diblock copolymers with a controlled number‐average molar mass ranging from 7 330 to 117 610 g · mol^?1 and an L ‐lactide conversion ranging from 65.1 to 97.3% were synthesized effectively in 20 min at 100 °C by MPEG‐initiated ROP of L ‐lactide under microwave irradiation. Prolonged microwave irradiation time led to the degradation of the copolymers because the ROP reaction and the thermal degradation reaction occurred simultaneously at the later stage of the reaction process. The differential scanning calorimetric and thermogravimetric study indicated that higher melting temperatures and thermal stability were obtained for PLLA‐MPEG diblock copolymers with longer PLLA segments.