A new method to improve the stability,tensile strength,and heat resistant properties of shape‐memory epoxy resins: Two‐stages curing

In this article, we design a new thermal curing method: two‐stage curing. The purpose of using this approach is to maintain the excellent shape‐memory property of epoxy resin system after first stage curing, and the material can be folded in small size to storage or transportation and recovery its original shape commodiously by heating temperature. Then, after second stage curing, the stability, glass transition temperature(T_g), and tensile strength of material can be improved effectively. For this aim, a series of mixtures have been prepared. Differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), tensile test, scanning electron microscope (SEM), dynamic mechanical analysis (DMA), and fold‐deploy shape‐memory test have been used to characterize the feasibility of two‐stage curing process, curing degree, tensile strength, morphology, thermodynamic properties, and shape‐memory performance of these polymers. DSC results show that two independent curing stages can be achieved successfully. Tensile tests and DMA results suggest that tensile strength and heat resistance have been improved after the second curing stage. SEM results reveal that the addition of latent curing agent do not change the fracture mechanism. Furthermore, the fold‐deploy shape‐memory tests prove that the composites after first stage curing possess eximious shape‐memory property. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39882.     

Caveolin-1 Limits the Contribution of BKCa Channel to MCF-7 Breast Cancer Cell Proliferation and Invasion

Increasing evidence suggests that caveolin-1 and large conductance Ca²⁺-activated potassium (BKCa) channels are implicated in the carcinogenesis processes, including cell proliferation and invasion. These two proteins have been proven to interact with each other in vascular endothelial and smooth muscle cells and modulate vascular contractility. In this study, we investigated the probable interaction between caveolin-1 and BKCa in MCF-7 breast cancer cells. We identified that caveolin-1 and BKCa were co-localized and could be reciprocally co-immunoprecipitated in human breast cancer MCF-7 cells. siRNA mediated caveolin-1 knockdown resulted in activation and increased surface expression of BKCa channel, and subsequently promoted the proliferation and invasiveness of breast cancer cells. These effects were attenuated in the presence of BKCa-siRNA. Conversely, up-regulated caveolin-1 suppressed function and surface expression of BKCa channel and exerted negative effects on breast cancer cell proliferation and invasion. Similarly, these opposing effects were abrogated by BKCa up-regulation. Collectively, our findings suggest that BKCa is a critical target for suppression by caveolin-1 in suppressing proliferation and invasion of breast cancer cells. The functional complex of caveolin-1 and BKCa in the membrane microdomain may be served as a potential therapeutic target in breast cancer.     

溶胶-凝胶工艺制备非氧化物超细粉体的研究现状

非氧化物材料因具有高熔点、高强度及优良的化学稳定性等优点而受到研究人员的普遍关注。综述了溶胶-凝胶(sol-gel)工艺制备非氧化物超细粉体的研究现状,总结了sol-gel工艺制备非氧化物超细粉体的优缺点,并提出了该技术今后潜在的发展方向。     

Identification of para‐Substituted Benzoic Acid Derivatives as Potent Inhibitors of the Protein Phosphatase Slingshot

Slingshot proteins form a small group of dual‐specific phosphatases that modulate cytoskeleton dynamics through dephosphorylation of cofilin and Lim kinases (LIMK). Small chemical compounds with Slingshot‐inhibiting activities have therapeutic potential against cancers or infectious diseases. However, only a few Slingshot inhibitors have been investigated and reported, and their cellular activities have not been examined. In this study, we identified two rhodanine‐scaffold‐based para‐substituted benzoic acid derivatives as competitive Slingshot inhibitors. The top compound, (Z)‐4‐((4‐((4‐oxo‐2‐thioxo‐3‐(o‐tolyl)thiazolidin‐5‐ylidene)methyl)phenoxy)methyl)benzoic acid ( D3 ) had an inhibition constant (K_i) of around 4 μm and displayed selectivity over a panel of other phosphatases. Moreover, compound D3 inhibited cell migration and cofilin dephosphorylation after nerve growth factor (NGF) or angiotensin II stimulation. Therefore, our newly identified Slingshot inhibitors provide a starting point for developing Slingshot‐targeted therapies.     

Synthesis and properties of silicon‐containing arylacetylene resins with polyhedral oligomeric silsesquioxane

A series of silicon‐containing arylacetylene resins containing polyhedral oligomeric silsesquioxane (PS resins) were synthesized by the hydrosilylation reaction between poly(dimethylsilyleneethynylenephenyleneethynylene) (PMSEPE) and octakis(dimethylsiloxy)octasilsesquoixane ( ) in the presence of a platinum catalyst (Pt‐dvs). The chemical structures and properties of PS resins were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, rheological analysis, differential scanning calorimetry, dielectric measurement, thermogravimetric analysis, and scanning electron microscopy. The results show that PS resins can be crosslinked to form thermosets at temperatures less than 260°C. With the increment of , the dielectric constants of the thermosets gradually decrease from 2.91 to 2.73. The thermooxidative stabilities of PMSEPE thermosets are obviously improved with the incorporation of . POLYM. ENG. SCI., 55:316–321, 2015. © 2014 Society of Plastics Engineers     

Nondestructive Estimation of Fat Constituents of Sesame (Sesamum indicum L.) Seeds by Near‐Infrared Reflectance Spectroscopy

A rapid and efficient method for oil constituent estimation in intact sesame seeds was developed through near‐infrared reflectance spectroscopy (NIRS) and was used to evaluate a sesame germplasm collection conserved in China. A total of 342 samples were scanned by reflectance NIR in a range of 950–1650 nm, and the reference values for oil content and fatty acid (FA) profiles were measured by Soxhlet and gas chromatograph methods. Useful chemometric models were developed using partial least squares regression with full cross‐validation. The equations had low standard errors of cross‐validation, and high coefficient of determination of cross‐validation (R_c²) values (>0.8) except for stearic acid (0.794). In external validation, r² values of oil and FA composition equations ranged from 0.815 (arachidonic acid) to 0.877 (linoleic acid). The relative predictive determinant (RPD_v) values for all equations were more than 2.0. The whole‐seed NIR spectroscopy equations for oil content and FA profiles can be used for sesame seed quality rapid evaluation. The background information of the 4399 germplasm resources and accessions with high linoleic acid content identified in this study should be useful for developing new sesame cultivars with desirable FA compositions in future breeding programs.     

Surface grafting of carbon fibers with artificial silver‐nanoparticle‐decorated graphene oxide for high‐speed electrical actuation of shape‐memory polymers

Poor heat conduction in the interface between the carbon fiber and polymer matrix is a problem in the actuation of shape‐memory polymer (SMP) composites by Joule heating. In this study, we investigated the effectiveness of grafting silver‐nanoparticle‐decorated graphene oxide (GO) onto carbon fibers to improve the electrothermal properties and Joule‐heating‐activated shape recovery of SMP composites. Self‐assembled GO was grafted onto carbon fibers to enhance the bonding of the carbon fibers with the polymeric matrix via van der Waal's forces and covalent crosslinking, respectively. Silver nanoparticles were further self‐assembled and deposited to decorate the GO assembly, which was used to decrease the thermal dissimilarity and facilitate heat transfer from the carbon fiber to the polymer matrix. The carbon fiber was incorporated with SMP to achieve the shape recovery induced by Joule heating. We found that the silver‐nanoparticle‐decorated GO helped us achieve a more uniform temperature distribution in the SMP composites compared to those without decoration. Furthermore, the shape‐recovery behavior and temperature profile during the Joule heating of the SMP composites were characterized and compared. A unique synergistic effect of the carbon fibers and silver‐nanoparticle‐decorated GO was achieved to enhance the heat transfer and a higher speed of actuation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41673.     

Insulin-Like Growth Factor-2 Is Induced Following 5-Aminolevulinic Acid-Mediated Photodynamic Therapy in SW620 Human Colon Cancer Cell Line

The IGF system is a family of polypeptide growth factors, which plays a significant role in the development and growth of many cells. Dysregulation of insulin-like growth factors and their pathway components has been connected with essential tumor properties, such as tumor cell proliferation, antiapoptotic properties, invasive behavior and chemotherapy resistance. However, the effects of photodynamic therapy (PDT), one of the cancer treatment methods for the regulation of the IGF signaling pathway, are still unclear. The aim of this study was to investigate the expression of IGF-2 after 5-aminolevulinic acid (5-ALA)-mediated-PDT in SW620 human colorectal cancer cells with evaluation of cell proliferation and apoptosis and to determine the effects of PDT on the IGF-2 receptor (IGF-2R), IGF-2 binding protein-1 (IGF-2BP-1) and the proapoptotic protein, BAX. Cells were treated with 5-aminolevulinic acid and its methyl ester. Changes of the expression and concentration of IGF-2 before and after treatment were assayed by immunocytochemistry, Western blot and ELISA. We found that IGF-2 was significantly overexpressed in the SW620 cell line, while its receptor and binding protein-1 were not significantly changed. Within this study, we would like to suggest that IGF-2 contributes to the effects of PDT and that its expression will influence post-PDT efficacy.     

Molecular Targeting of the Oncoprotein PLK1 in Pediatric Acute Myeloid Leukemia: RO3280, a Novel PLK1 Inhibitor,Induces Apoptosis in Leukemia Cells

Polo-like kinase 1 (PLK1) is highly expressed in many cancers and therefore a biomarker of transformation and potential target for the development of cancer-specific small molecule drugs. RO3280 was recently identified as a novel PLK1 inhibitor; however its therapeutic effects in leukemia treatment are still unknown. We found that the PLK1 protein was highly expressed in leukemia cell lines as well as 73.3% (11/15) of pediatric acute myeloid leukemia (AML) samples. PLK1 mRNA expression was significantly higher in AML samples compared with control samples (82.95 ± 110.28 vs. 6.36 ± 6.35; p < 0.001). Kaplan-Meier survival analysis revealed that shorter survival time correlated with high tumor PLK1 expression (p = 0.002). The 50% inhibitory concentration (IC₅₀) of RO3280 for acute leukemia cells was between 74 and 797 nM. The IC₅₀ of RO3280 in primary acute lymphocytic leukemia (ALL) and AML cells was between 35.49 and 110.76 nM and 52.80 and 147.50 nM, respectively. RO3280 induced apoptosis and cell cycle disorder in leukemia cells. RO3280 treatment regulated several apoptosis-associated genes. The regulation of DCC, CDKN1A, BTK, and SOCS2 was verified by western blot. These results provide insights into the potential use of RO3280 for AML therapy; however, the underlying mechanisms remain to be determined.     

High performance modification of hyperbranched polyborate on diglycidyl ether of bisphenol‐a resin

High performance epoxy resin was obtained by introducing hyperbranched polyborate (HBPB) into diglycidyl ether of bisphenol A (DGEBA) resin to overcome the defects such as low char yield and poor toughness of DGEBA resin. By virtue of the massive functional end groups, hyperbranched and rigid boron‐containing structures of HBPB, the thermal resistance of DGEBA resin cured with diamino diphenyl sulfone (DDS) can be greatly improved. Moreover, with the toughening effect of hyperbranched structures of HBPB, the mechanical properties such as flexural strength and interlaminar shear strength of the carbon fiber reinforced DGEBA‐DDS composite could be greatly increased by HBPB without a decrease on modulus and glass transition temperature of DGEBA‐DDS resin. POLYM. COMPOS. 36:424–432, 2015. © 2014 Society of Plastics Engineers