Core-Shell Structured Magnetite-Poly(diphenylamine) Microspheres and Their Tunable Dual Response under Magnetic and Electric Fields.

Core-shell type poly(diphenylamine)-coated magnetite (Fe3O4-PDPA) microspheres were designed and adopted as a novel actively tunable smart material which is responsive under both electric and magnetic fields. Their morphology, chemical structure, crystalline structure, and thermal properties were characterized using scanning electron microscopy, transmission electron microscope, Fourier transform-infrared spectroscopy, X-ray diffraction, and a thermal gravimetric analyzer. Their magnetic and dielectric properties were determined using vibrating-sample magnetometer and an LCR meter, respectively. They were dispersed in silicone oil and their electrorheological (ER) and magnetorheological (MR) responses under the electric and magnetic fields, respectively, were examined. The formation of chain structure of Fe3O4-PDPA based E/MR fluid under the application of electric field or magnetic field was observed by an optical microscopy and the sedimentation stability was observed by a Turbiscan optical analyzer system. It was observed that the yield stress, ER efficiency, and leakage current density increased with an increase in the particle concentration, while the slope of the electric field-dependent yield stress decreased. Several models such as the Bingham model, Herschel-Bulkley model, and Cho-Choi-Jhon equations were used to describe the shear stress curves of the ER fluid; the curves fitted well. For the dielectric properties, the two types of ER fluids tested displayed the same relaxation time and distribution; however, the one with the higher concentration had a higher dielectric constant and polarizability. The Fe3O4-PDPA based MR fluid (10 vol %) exhibited typical MR properties. In addition, the Herschel-Bulkley model matched well with the shear stress curves under a magnetic field.

Pickering Emulsion Polymerized Polyaniline/Zinc-ferrite Composite Particles and Their Dual Electrorheological and Magnetorheological Responses.

A functional raspberry-like core-shell composite particle consisting of a conducting polyaniline (PANI) core and magnetic zinc ferrite shell is synthesized by Pickering emulsion polymerization. The morphology and chemical structure of the PANI/zinc-ferrite composite are evaluated by scanning electron microscopy, transmission electron microscopy, and Fourier-transform infrared spectroscopy. An electrorheological/magnetorheological fluid consisting of the PANI/zinc-ferrite composite dispersed in silicone oil with a particle concentration of 5 vol % is fabricated. Its rheological characteristics under external electric and magnetic fields are investigated by using a rotational rheometer. Under the electric or magnetic field, the PANI/zinc-ferrite particles form chain-like structures, demonstrating a solid-like state.

Nanoparticles Functionalized by Conducting Polymers and Their Electrorheological and Magnetorheological Applications.

Conducting polymer-coated nanoparticles used in electrorheological (ER) and magnetorheological (MR) fluids are reviewed along with their fabrication methods, morphologies, thermal properties, sedimentation stabilities, dielectric properties, and ER and MR characteristics under applied electric or magnetic fields. After functionalization of the conducting polymers, the nanoparticles exhibited properties suitable for use as ER materials, and materials in which magnetic particles are used as a core could also be applied as MR materials. The conducting polymers covered in this study included polyaniline and its derivatives, poly(3,4-ethylenedioxythiophene), poly(3-octylthiophene), polypyrrole, and poly(diphenylamine). The modified nanoparticles included polystyrene, poly(methyl methacrylate), silica, titanium dioxide, maghemite, magnetite, and nanoclay. This article reviews many core-shell structured conducting polymer-coated nanoparticles used in ER and MR fluids and is expected to contribute to the understanding and development of ER and MR materials.

Electrorheological Characteristics of Poly(diphenylamine)/magnetite Composite-Based Suspension.

Electro-responsive poly(diphenylamine)(PDPA)/Fe3O4 composite particles were prepared by the synthesis of PDPA particles using a chemical oxidative polymerization technique followed by loading nano-sized Fe3O4 particles onto PDPA via a chemical co-precipitation process. The morphological image of the PDPA/Fe3O4 particles was characterized by scanning electron microscope and transmission electron microscope. The crystalline structure was scrutinized by X-ray diffraction. The rheological characteristics of the suspension composed of PDPA/Fe3O4 particles suspended in silicone oil were investigated by a rotation rheometer, demonstrating standard electrorheological (ER) characteristics with a dramatic increase in shear stress and dynamic moduli under the application of an electrical field strength. The shear stress curves under an electrical field could be described using the Bingham model and the yield stress showed a power-law relationship with the electric field strength with an exponent of 1.5, following the conduction model. Furthermore, the frequency-dependent dielectric behaviors of the PDPA/Fe3O4 ER suspension was tested using an inductance (L)-capacitance (C)-resistance (R) (LCR) meter. The dielectric properties were well described using the Cole-Cole equation and were consistent with the results of the ER experiments.

Graphene Oxide and Its Inorganic Composites: Fabrication and Electrorheological Response.

Composite particles associated with graphene oxide (GO) and inorganic materials provide the synergistic properties of an appropriate electrical conductivity of GO with the good dielectric characteristics of inorganic materials, making them attractive candidates for electrorheological (ER) materials. This review paper focuses on the fabrication mechanisms of GO/inorganic composites and their ER response when suspended in a non-conducting medium, including steady shear flow curves, dynamic yield stress, On-Off tests, and dynamic oscillation analysis. Furthermore, the morphologies of these composites, dielectric properties, and sedimentation of the ER fluids are covered.

Recent development of electro-responsive smart electrorheological fluids.

The characteristics of an electrorheological (ER) fluid, as a class of smart soft matter, can be actively and accurately tuned between a liquid- and a solid-like phase by the application of an electric field. ER materials used in ER fluids are electrically polarizable particles, which are attracting considerable attention in addition to further research. This perspective reports the latest ER materials along with their rheological understanding and provides a forward-looking summary of the potential future applications of ER technology.

Polyaniline Coated Core-Shell Typed Stimuli-Responsive Microspheres and Their Electrorheology.

Functional core-shell-structured particles have attracted considerable attention recently. This paper reviews the synthetic methods and morphologies of various electro-stimuli responsive polyaniline (PANI)-coated core-shell-type microspheres, including PANI-coated Fe3O4, SiO2, Fe2O3, TiO2, poly(methyl methacrylate), poly(glycidyl methacrylate), and polystyrene along with their electrorheological (ER) characteristics when prepared by dispersing these particles in an insulating medium. In addition to the various rheological characteristics and their analysis, such as shear stress and yield stress of their ER fluids, this paper summarizes some of the mechanisms proposed for ER fluids to further understand the responses of ER fluids to an externally applied electric field.

Electroresponsive Polymer-Inorganic Semiconducting Composite (MCTP-Fe3O4) Particles and Their Electrorheology.

Polymer-inorganic semiconducting composite (MCTP-Fe3O4) particles were fabricated by loading nanosized Fe3O4 on the microporous covalent triazine-based polymer (MCTP) through a chemical coprecipitation method and then applied to an electrorheological (ER) material. The structural and morphological images of MCTP-Fe3O4 composite were examined by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. Their magnetic property was also investigated by vibrating sample magnetometry. The chain structure formation of MCTP-Fe3O4 dispersed in silicone oil under an external electric field was confirmed using an optical microscope. The ER fluid based on MCTP-Fe3O4 was processed by dispersing the composite particles in an oil medium, and for comparison, an ER fluid based on pure MCTP was also prepared by the same process. The ER performance of two different ER fluids was scrutinized by a rotational rheometer, which demonstrated that MCTP-Fe3O4 showed better ER characteristics than MCTP-based ER suspension.

Effects of exogenous neurotrophin-3 on myocyte apoptosis and Ca(2+)-ATP enzyme levels following nerve injury in rats.

This study aims to determine the influence of neurotrophin-3 (NT-3) plasmids on neuronal apoptosis and Ca(2+)-ATP enzyme levels in injured muscles. We also investigated the mechanism underlying the role of NT-3 in delaying muscle atrophy following a peripheral nerve injury. Sixty adult Wistar rats were used to generate the peripheral nerve injury models. The rats were randomly assigned to the saline and NT-3 groups. Related indicators, such as caspase-3 protein expression, skeletal muscle cell apoptosis, and Ca(2+)-ATP enzyme expression were quantified. The expression levels of caspase-3 and the histone-muscle cell apoptosis rate in the NT-3 group decreased at different post-operative times following peripheral nerve injury, whereas NT-3 expression and the sarcoplasmic reticulum Ca(2+)-ATP enzyme levels increased. Statistically significant differences were observed in the NT-3 group as compared to the saline group (P < 0.05). NT-3 mitigated muscle atrophy following peripheral nerve damage by inhibiting caspase-3 gene expression and increasing Ca(2+)-ATP enzymatic activity, ultimately reducing muscle apoptosis.

The association of XPG and MMS19L polymorphisms response to chemotherapy in osteosarcoma.

OBJECTIVE: To assess the role of XPG, XPC, CCNH and MMS19L polymorphisms response to chemotherapy in osteosarcoma, and the clinical outcome of osteosarcoma. METHODS: One hundred and sixty eight osteosarcoma patients who were histologically confirmed were enrolled in our study between January 2007 and March 2009. Genotyping of XPG, XPC, CCNH and MMS19L was performed in a 384-well plate format on the MassARRAY® platform. RESULTS: Individuals with rs2296147 TT genotype showed a better response as compared with CC genotype, with the OR (95% CI) of 3.89(1.49-10.95). Those carrying rs29001322 TT genotype presented better response to chemotherapy, and the OR (95% CI) was as high as 12.25(2.63-121.84). Patients carrying TT genotype of XPG rs2296147 and MMS19L rs29001322 showed a significantly longer overall survival than CC genotype, they had 0.37 and 0.31-fold risk of death when compared with wide-type of this gene. CONCLUSIONS: XPG rs2296147 and MMS19L rs29001322 are correlated with response to chemotherapy and prognosis of osteosarcoma. Our findings would provide important evidence for prognostic and therapeutic implications in osteosarcoma.

[Study of animal model of hypertensive disorder complicating pregnancy in pregnant rats stimulated by homocysteine and monosodium glutamate].

OBJECTIVE: To determine whether homocysteine (Hcy) and monosodium glutamate (MSG) could lead to animal model of hypertensive disorder complicating pregnancy and its mechanism. METHODS: Female adult Wistar rats were randomly divided into 4 groups: pregnant control group (PN), pregnant Hcy group (PH), pregnant glutamic acid group (PG) and pregnant Hcy and glutamic acid group (PHG). The rats of each group were injected with Hcy 200 mg/kg or physiological saline every day intraperitoneally and with MSG or 0.9% saline every other day via Hcy injection from the 10th day to the 20th day of pregnancy. The blood pressure, urine protein, function of liver and kidney, weight of placenta, length and weight of fetus were all measured. The histological change of the pallium and the change of behavior of pregnant rats were also observed. RESULTS: (1) The blood pressure in PH [(107 +/- 8) mm Hg, 1 mm Hg = 0.133 kPa], and PHG group [(109 +/- 10) mm Hg] after the treatment increased significantly compared with those in other groups from the 12 th day after pregnancy (P < 0.01). (2) The level of urine protein [(1.42 +/- 0.53) g/L, (1.53 +/- 0.24) g/L] in PH and PHG groups after the treatment was significantly higher than the other groups (P < 0.01). (3) Obvious changes of the function of liver and kidney [alanine aminotransferase (ALT) (57 +/- 15) U/L, (69 +/- 24) U/L, aspartate aminotransferase (AST) (265 +/- 61) U/L, (293 +/- 118) U/L, blood urea nitrogen (BUN) (9.5 +/- 0.8) mmol/L, (9.5 +/- 1.6) mmol/L, creatinine (Cr) (54 +/- 10) micromol/L, (54 +/- 10) micromol/L], were found in PHG group and PH group (P < 0.01). (4) The weight of placenta [(0.49 +/- 0.28) g, (0.45 +/- 0.03) g], length and weight of fetus [(3.6 +/- 1.5) cm, (3.5 +/- 1.5) cm] in PH group and PHG group were significantly lower than that in PN group and PG group (P < 0.01). Obvious histological changes in pallium and kidney were found in PH group and PHG group. Changes of behavior were found in PHG group. CONCLUSION: Hcy and MSG could induce the symptoms of hypertensive disorder complicating pregnancy in pregnant rats, especially pre-eclampsia, possibly through injuring vascular endothelial cell and nerve cell of the cerebral cortex.

[Effect of interleukin-6 on gene expression of certain cytokines during wound healing process of mouse skin].

To examine the effect of the interlukin-6 (IL-6) in wound healing process, gene expression profiles of cytokines including interlukin-1alpha (IL-1alpha), interlukin-1beta (IL-1beta), keratinocyte chemoattractant (KC), macrophage inflammatory protein-1alpha (MIP-1alpha), and macrophage inflammatory protein-2 (MIP-2) during the skin wound healing on the IL-6(+/+) and IL-6(-/-) mice were detected using immunochemical staining and RT-PCR methods at different phases after wound. The results showed that these cytokines were expressed at early phage after wound, and a expressing peak were found on the third day after wound, and decreased on the sixth day after wound. Meanwhile, on the third and sixth day after wound, all the levels of the five cytokines expressed of the IL6(-/-) mice were significantly lower than those of the IL-6(+/+) mice, but on the first day after wound, only the levels of MIP-1alpha and KC of the IL-6(-/-) mice were lower. The process of skin wound healing was later in IL-6(-/-) mice than that in IL-6(+/+) mice, but it was complete in IL-6(-/-) mice. These results showed that IL-6 induce expression of the other five cytokines detected, and advance the repair of the wound on skin of mice, but in the mice of IL-6 deletion, the wound healing process was not disturbed significantly.