Preparation of Octadecylamine-Graphene/MgCl2-Supported Ziegler-Natta Catalyst and Its Application in Ethylene Polymerization.

A facile coagglomeration method for preparing a long alkyl chain modified graphene oxide (MGO)/MgCl2-supported Ti-based Ziegler-Natta catalyst was reported. The effects of MGO on the catalyst morphology and activity for ethylene polymerization were examined. The resultant polyethylene (PE)/MGO nanocomposites exhibited a layered morphology, with the MGO fillers being well dispersed and exhibiting strong interfacial adhesion to the PE matrix. The thermal stability and mechanical properties of the PE were significantly enhanced with the introduction of a small amount of the MGO filler. Thus, this work provides a facile approach to the production of high-performance PE.

Preparation of Isotactic Polypropylene/Exfoliated MoS2 Nanocomposites via In Situ Intercalative Polymerization.

In this research, a Ziegler⁻Natta catalyst intercalated MoS2 was synthesized through the intercalation of a Grignard reagent into MoS2 galleries, followed by the anchoring of TiCl4. During propylene polymerization, the intercalated MoS2 exfoliated in situ to form PP/exfoliated MoS2 (EMoS2) nanocomposites. The isotactic index values of the resultant PP/EMoS2 nanocomposites were as high as 99%, varying from 98.1% to 99.0%. It was found that the incorporation of the EMoS2 significantly improved the thermal stability and mechanical properties (tensile strength, modulus, and elongation at break) of PP. After introduction of EMoS2, the maximum increases in Td5% and Tdmax were 36.9 and 9.7 °C, respectively, relative to neat PP. After blending with commercial PP, the resultant nanocomposites increase in tensile strength and modulus up to 11.4% and 61.2% after 0.52 wt % EMoS2 loading. Thus, this work provides a new way to produce high-performance PP.

[Case-control study on the iliac bone flap transplantation with deep circumflex iliac artery and quadratus femoris bone flap transplantation for the treatment of Garden III/IV femoral neck fracture of young and middle-aged patients].

OBJECTIVE: To compare the clinical effects between hip anterior S-P approach combined with iliac bone flap transplantation with deep circumflex iliac artery and posterior K-L approach combined with quadratus femoris bone flap transplantation for the treatment of femoral neck fracture of Garden III-IV in young and middle-aged patients. METHODS: From January 2004 to January 2011,46 patients with femoral neck fractures were treated by two kinds of operation. Among them, 20 cases were treated with anterior S-P approach combined with iliac bone flap transplantation with deep circumflex iliac artery, included 12 males and 8 females with an average age of (32.1 ± 7.3) years old, involved 12 cases of Garden III and 8 cases of Garden IV. The other 26 cases were treated with posterior K-L approach combined with quadratus femoris bone flap transplantation, included 20 males and 6 females with an average age of (37.8 ± 6.9) years old, involved 16 cases of Garden III and 10 cases of Garden IV. The index of hospitalization (hospitalization time, total cost, operative time, intraoperative blood loss, postoperative complications), the quality index of operation (fracture reduction, position of internal fixation, fracture healing time, nonunion and femoral head necrosis) of two groups were observed and compared. Hip joint function were evaluated by Harris score. RESULTS: All patients were followed up from 28 to 41 months with an average of 36 months. The intraoperative blood loss of group S-P (92.3 ± 10.4) ml was less than that of group K-L (132.4 ± 11.2) ml, there was significant difference between two groups (P < 0.05). The operation time of group S-P (81.4 ± 9.2) min was more than that of group K-L (67.1 ± 4.5) min, the difference was statistically significant (P < 0.05). One case in group S-P and 9 cases in group K-L appeared postoperative complications, there was significant difference between two groups (P < 0.05). The fracture healing time of S-P group (83.5 ± 7.3) d was shorter than that of group K-L (103.2 ± 12.6) d, there was significant difference between two groups (P < 0.05). At 30 months after operation, there were significant difference in Harris scoring between two groups (P < 0.05). CONCLUSION: Anterior S-P approach combined with iliac bone flap transplantation with deep circumflex iliac artery for treatment of femoral neck fracture of Garden III-IV of young and middle-aged patients, it has characteristics in clear anatomic and easy to operate. As compared with K-L approach, S-P approach can better reserve residual blood supply of femoral neck. While combining with the iliac bone flap transplantation with deep circumflex iliac artery, it could better reconstruct the blood supply of femoral neck to promote fracture healing.

Preparation of Au Nanoparticles Immobilized Cross-Linked Poly(4-vinylpyridine) Nanofibers and Their Catalytic Application for the Reduction of 4-Nitrophenol.

Catalytic nanofibers are prepared by the immobilization of Au nanoparticles (AuNPs) onto the surface of cross-linked electrospun poly(4-vinylpyridine) (P4VP) nanofibers. The crosslinking of the P4VP nanofibers by 1,4-diiodobutane via quaternization reaction greatly enhances the stability of the nanofibers against the solvent dissolution, which can then be used as promising platform for the immobilization of catalytic metal nanoparticles. The AuNPs immobilized cross-linked P4VP nanofibers have shown a good catalytic activity for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP).

Preparation and morphology of polyethylene/clay nanocomposite with novel MgCl2/montmorillonite (MMT) bi-supported Ziegler-Natta catalyst.

In the present article, the spherical and high activity TiCl4/MgCI2/MMT intercalated catalyst was successfully prepared. The active centers of obtained catalyst well dispersed in the MMT through electron probe micro-analysis (EPMA). The d-spacing of MMT was broadened from 0.97 nm to 1.42 nm after addition of MgCl2 and the space between MMT layers was 1.60 nm after treated with excess TiCl4. In addition, the catalyst shows a very high activity toward ethylene polymerization. During the ethylene polymerization, the MMT layers were exfoliated by the polymerization force arising from the propagation of ethylene chain. Interestingly, the macro-scale morphology of the obtained polyethylene (PE)/MMT nanocomposite still retained the spherical shape of precursor catalyst; while the PE particles contain MMT platelets take the shape of "flower petal" in the micro-scale. Transmission electron microscopy (TEM) photographs showed that the MMT homogeneously dispersed in the PE.

Preparation of superhydrophobic cross-linked syndiotactic 1,2-polybutadiene membranes by electrospinning.

In this study, syndiotactic 1,2-polybutadiene (s-PB)/azobisisobutyronitrile (AIBN) membranes were prepared via electrospinning. The obtained membranes were intensively investigated by contact angle analyzer, differential scanning calorimetry (DSC) and environmental scanning electron microscope (ESEM). With increasing the concentration of spinning solution, the obtained membranes were changed from hydrophobic to surperhydrophobic and the contact angle (CA) as high as 157 degrees at higher s-PB concentration. In addition, the s-PB/AIBN membrane cross-linked completely through heat treatment and superhydrophobic property of s-PB/AIBN membrane has not changed. The diameter of cross-linked fiber-based membrane was much thinner than that of the uncross-linked fibers.

[Advances in the study on the role of connective tissue in the mechanical signal transduction of acupuncture].

Non-specific connective tissue (fascia connective tissue) plays an important role in the mechanical signal transduction of acupuncture. Acupuncture needle manipulation-induced mechanical stress has a certain effect on the fibroblasts and cytoskeleton in the nonspecific connective tissue (including loose connective tissue and fat tissue) in morphology, histochemistry and biochemistry. For example, acupuncture-needle manipulation can make the fibroblast deformed, the cytoskeleton remodeled and result in the release of biochemical materials from the connective tissue. The present review summarizes new results of studies on the effect of acupuncture needle manipulation from cytobiology, imageology and physiology; and holds that making clear the transduction pathways of acupuncture mechanical stress signals in the connective tissue and its impact on the organism possesses an important significance in revealing the mechanism of acupuncture underlying clinical therapeutic effects.

[Expression of extracellular signal-regulated protein kinases in the subcutaneous fascia of rats and their changes after acupuncture].

OBJECTIVE: To observe the effect of acupuncture on the expression of extracellular signal-regulated protein kinases 1/2 (ERK1/2) in the subcutaneous fascia of SD rats. METHODS: Eighteen SD rats were randomly divided into 6 groups (n=3) including 5 acupuncture groups and a control group. The rats in the 5 acupuncture groups received electro-acupuncture therapy in the regions of the inguinal groove, and at 0, 1, 6, 12, and 36 h after the last therapy, the superfacial fascia surrounding the acupuncture point (about 1.5 cm in diameter) were collected. The fascia tissues at the corresponding sites and at the acupoint Zusanli (ST36) were obtained from the control rats. The expression of ERK1/2 and phosphorylated ERK1/2 (p-ERK1/2) in the tissues were detected by Western blotting. RESULTS: ERK1/2 and p-ERK1/2 expressions were detected in the tissues harvested from both the acupoint and the non-acupoint in the control rats with similar expression intensities. In the rats of each acupuncture group, ERK1/2 expression was significantly increased on the acupuncture side in comparison with the control side. CONCLUSION: The normal loose connective tissue may participate in tissue proliferation and differentiation possibly via phosphorylation of ERK. Acupuncture can promote the signal transduction pathway of ERK, which can be a possible mechanism for the effect of acupuncture in modulating the physiopathological conditions.

[Biocompatibility between human adipose-derived mesenchymal stem cells and porcine bone scaffolds].

OBJECTIVE: To study the compatibility between human adipose-derived mesenchymal stem cells and porcine bone scaffolds. METHODS: Porcine bone tissues were co-cultured with adipose-derived mesenchymal stem cells, and the complex was observed under scanning electron microscope. The viability and alkaline phosphatase (ALP) activity of the cells were examined with the cells co-cultured with human bone scaffold as the control. RESULTS: At 4 and 10 days after the co-culture, the adipose-derived mesenchymal stem cells were observed to extend pseudopodia to adhere to the two scaffold materials. MTT assay showed that the cell proliferation on both of the materials increased with time, and the two cell complexes exhibited similar pattern of changes in ALP activity. CONCLUSION: As the seed cells, human adipose-derived mesenchymal stem cells exhibit good comparability with porcine bone scaffold, suggesting their potential of constructing tissue-engineered bone graft.