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  • 1
    Language: English
    In: Journal of Membrane Science, Sept 15, 2013, Vol.443, p.170(11)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.memsci.2013.04.062 Byline: Yuan Zhang, Rong Wang Abstract: Hydrophobic surface can be produced by either lowering the surface free energy or enhancing the surface roughness or a combination of both. This study explored a novel method to form a highly hydrophobic organic-inorganic composite hollow fiber membrane by incorporating the fluorinated silica (fSiO.sub.2) inorganic layer on the polyetherimide (PEI) organic substrate. The formation of the composite membrane was examined and confirmed by ATR-FTIR, TGA and SEM. Ultrasonication test was conducted to examine the structural stability of the composite membrane. The experimental results revealed that the fSiO.sub.2 layer was tightly bonded to the PEI substrate through silane chemical reactions. The incorporation of the fSiO.sub.2 layer on the membrane surface could enhance the surface roughness and greatly reduce the surface free energy due to the hydrophobic compound perfluorodecyltriethoxysilane (PFTS). The hydrophobicity of the composite membrane surface was dramatically elevated, as evidenced by the dynamic contact angles increment, e.g. from original 66.7[degrees] to 124.8[degrees] for advancing values, and from 49.5[degrees] to 100.6[degrees] for receding values. In addition, it was observed the mechanical property of the composite membrane was better than some of the conventional polymeric membranes such as polyethersulfone (PES), and polyvinylidene fluoride (PVDF). The composite membrane was also not as brittle as the pure inorganic membrane. Highly hydrophobic membrane is the core element in gas-liquid membrane contactor and the newly developed PEI-fSiO.sub.2 composite hollow fiber membranes were intended for the use in such application. The CO.sub.2 absorption flux of the composite membranes was investigated in both physical and chemical absorptions in a gas-liquid membrane contactor system. Moreover, the membrane contactor showed a reasonably stable performance throughout the 31 days long-term operation using a 2M sodium taurinate aqueous solution as the liquid absorbent and pure CO.sub.2 as the feed gas. The chemical compatibility test indicated that after the long-term constant contact with the sodium taurinate, the hydrophobicity of the PEI-fSiO.sub.2 composite membrane still maintained and was much higher than that of original PEI substrate and conventional hydrophobic polymeric membranes such as PVDF. The incorporation of the fSiO.sub.2 inorganic layer not only offered high hydrophobicity, but also would protect the polymeric substrate from the attacks of chemical absorbents, making the membrane a longer lifespan. Author Affiliation: (a) School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore (b) Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore 637141, Singapore Article History: Received 25 February 2013; Revised 27 April 2013; Accepted 27 April 2013
    Keywords: Green Technology ; Silicon Dioxide ; Polyvinylidene Fluoride ; Polyetherimide ; Silanes
    ISSN: 0376-7388
    Source: Cengage Learning, Inc.
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  • 2
    Language: English
    In: Journal of Membrane Science, Feb 15, 2014, Vol.452, p.379(11)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.memsci.2013.10.011 Byline: Yuan Zhang, Rong Wang Abstract: In a gas-liquid membrane contactor, a larger pore size can result in a lower membrane mass transfer resistance. However, the membrane pore size is usually limited by the concern of pore wetting, e.g. a large pore size means a higher wetting tendency. As a breakthrough, this paper reported a porous polyetherimide (PEI) hollow fiber membrane with high surface porosity and large pore size to minimize the membrane mass transfer resistance by using a triple-orifice spinneret in the hollow fiber spinning process, and followed by a novel approach of fluorinated silica (fSiO.sub.2) nanoparticles (NPs) incorporation to make the membrane surface highly hydrophobic and chemical resistant to prevent the membrane from wetting caused by the large pore size on the membrane surface. The newly developed composite hollow fiber membranes showed the advancing contact angle value of 123.3[degrees], receding contact angle value of 107.2[degrees], and contact angle hysteresis of only 15.9[degrees], indicating the high water resistant property. The composite membrane also exhibited a higher rigidity property compared with the original PEI substrate. The CO.sub.2 absorption flux of the composite membranes was investigated in both physical and chemical absorptions in a gas-liquid membrane contactor system. The membrane contactor showed a stable performance throughout the 60d long-term operation using a 2M sodium taurinate aqueous solution as the liquid absorbent. The highly hydrophobic composite hollow fiber membrane was able to outperform a conventional polymeric hydrophobic membrane in term of superior gas absorption flux and outstanding long-term stability, suggesting that the formation of organic-inorganic composite membranes is an effective way to enhance the feasibility of membrane contactor processes for practical applications. The results demonstrated the important role of membrane fabrication and modification techniques in facilitating the commercialization of membrane contactor technology. Author Affiliation: (a) School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore (b) Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore 637141, Singapore Article History: Received 11 June 2013; Revised 3 October 2013; Accepted 6 October 2013
    Keywords: Silicon Dioxide -- Analysis ; Silicon Dioxide -- Methods ; Nanoparticles -- Analysis ; Nanoparticles -- Methods ; Green Technology -- Analysis ; Green Technology -- Methods ; Porosity -- Analysis ; Porosity -- Methods ; Polyetherimide -- Analysis ; Polyetherimide -- Methods
    ISSN: 0376-7388
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: Journal of Applied Physics, 15 January 2012, Vol.111(2)
    Description: A universal model and experiments on the polarization switching for ferroelectric poly(vinylidene fluoride-trifluoroethylene) copolymer ultra-thin films with an interface layer have been studied. It is found that polarization switching could complete if the capacitance of the interface layer is large enough compared with that of the ferroelectric film. Based on this model, a conducting polymer, poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonic) acid, is introduced as an interface layer between metal electrodes and ferroelectric polymer film and the switching property measurements well agree with the simulation results of the model. These findings provide an effective route to enhance the polarization switching for the ferroelectric films, which is promising for potential applications.
    Keywords: Articles
    ISSN: 0021-8979
    E-ISSN: 1089-7550
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  • 4
    Language: English
    In: Journal of Applied Physics, 15 March 2012, Vol.111(6)
    Description: The high-temperature ferroelectric behaviors for poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer ultrathin films with electroactive interlayers have been studied. The different electroactive polymers, commercial poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonic) acid (PEDOT-PSSH), in situ synthesized PEDOT-PSSH with high PEDOT ratio and poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonic) ammonia (PEDOT-PSSNH 4 ), are used as the interlayer between P(VDF-TrFE) and metal electrodes. It is found that the ferroelectric properties at high temperature are strongly dependent on the interlayer and the faster degradation occurs on the sample with the interlayer which has enough protons as compensating charges. Further analysis on the polarization response behaviors and capacitance shows that the high-temperature ferroelectric properties are more closely associated with the compensating charges in interlayer than the ferroelectric film itself, illustrating the importance of the appropriate interlayer materials.
    Keywords: Articles
    ISSN: 0021-8979
    E-ISSN: 1089-7550
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  • 5
    Language: English
    In: Biomaterials, April 2013, Vol.34(13), pp.3447-3458
    Description: Nucleoside analogs are a significant class of anti-cancer agent. As prodrugs, they terminate the DNA synthesis upon transforming to their active triphosphate metabolites. We have encapsulated a biologically activate nucleotide analog (i.e. gemcitabine triphosphate (GTP)), instead of the nucleoside (i.e. gemcitabine) derivative, into a novel Lipid/Calcium/Phosphate nanoparticle (LCP) platform. The therapeutic efficacy of LCP-formulated GTP was evaluated in a panel of human non-small-cell lung cancer (NSCLC) and human pancreatic cancer models after systemic administrations. GTP-loaded LCPs induced cell death and arrested the cell cycle in the S phase. efficacy studies showed that intravenously injected GTP-loaded LCPs triggered effective apoptosis of tumor cells, significant reduction of tumor cell proliferation and cell cycle progression, leading to dramatic inhibition of tumor growth, with little toxicity. Broadly speaking, the current study offers preclinical proof-of-principle that many active nucleotide or phosphorylated nucleoside analogs could be encapsulated in the LCP nanoplatform and delivered systemically for a wide variety of therapeutic applications.
    Keywords: Lcp Nanoparticle ; Gemcitabine Triphosphate ; Apoptosis ; Proliferation ; Cell Cycle Progression ; Medicine ; Engineering
    ISSN: 0142-9612
    E-ISSN: 1878-5905
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  • 6
    Language: English
    In: Biomaterials, November 2013, Vol.34(33), pp.8459-8468
    Description: The treatment of aggressive non-small-cell lung cancer (NSCLC) depends on the creation of new therapeutic regimens in clinical settings. In this study, we developed a Lipid/Calcium/Phosphate (LCP) nanoparticle that combines chemotherapy with gene therapy. By encapsulating a chemodrug, gemcitabine monophosphate (GMP), and siRNA specific to the undruggable cMyc oncogene (cMyc siRNA) into a single nano-sized vesicle and systemically administering them to nude mice, we achieved potent anti-tumor activity in both subcutaneous and orthotopic models of NSCLC. The improvements in therapeutic response over either cMyc siRNA or GMP therapy alone, were demonstrated by the ability to effectively induce the apoptosis of tumor cells and the significant reduction of proliferation of tumor cells. The combination therapy led to dramatic inhibition of tumor growth, with little toxicity. Additionally, the current studies demonstrated the possibility of incorporating both nucleic acid molecules and phosphorylated small molecule drugs into the inner core of a single nanoparticle formulation. Co-encapsulation of an oncogene-modulating siRNA and a chemotherapeutic agent will allow simultaneous interruption of diverse anti-cancer pathways, leading to increased therapeutic efficacy and reduced toxicities.
    Keywords: C-Myc Sirna ; Gemcitabine Monophosphate ; Calcium Phosphate Nanoparticle ; Apoptosis ; Proliferation ; Medicine ; Engineering
    ISSN: 0142-9612
    E-ISSN: 1878-5905
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  • 7
    Language: English
    In: Biochemical and Biophysical Research Communications, 22 June 2012, Vol.423(1), pp.26-31
    Description: ► Sirt3 protein level was downregulated in human hepatocellular carcinoma (HCC) tissue. ► Sirt3-overexpression (Sirt3-OE) inhibited HCC cell growth and induced apoptosis. ► Sirt3-OE modulated NAD level, ERK, p38 and JNK pathways in HCC cells. ► Sirt3-OE upregulated p53 protein through downregulating Mdm2 to slow p53 degradation. Sirt3 is a member of the mammalian sirtuin family that is localized to mitochondria and plays a role in the control of the metabolic activity. Recently, Sirt3 has been reported to be associated with the deregulating metabolism of cancer cells. However, the role of Sirt3 in hepatocellular carcinoma (HCC) has never been studied. In this study, we found that Sirt3 protein expression was downregulated in human HCC tissue. We also showed that overexpression of Sirt3 using adenovirus inhibited HCC cell growth (two cell lines: HepG2 and HuH-7 cells) and induced apoptosis, which was evidenced by the increase of LDH leakage, enhancement of TUNEL-positive cells number and promotion of AIF translocation to nuclei. Sirt3 overexpression reduced the intracellular NAD level, repressed the ERK1/2 signaling pathway, and activated the Akt and JNK signaling pathways. Furthermore, Sirt3 overexpression upregulated p53 protein level through downregulating Mdm2 and thereby slowing p53 degradation. Collectively, our data suggests that Sirt3 may play an important role in HCC development and progression and may be a promising therapeutic target for HCC.
    Keywords: Sirt3 ; Hepatocellular Carcinoma ; P53 ; Mdm2 ; Biology ; Chemistry ; Anatomy & Physiology
    ISSN: 0006-291X
    E-ISSN: 1090-2104
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  • 8
    Language: English
    In: Tetrahedron Letters, 21 November 2018, Vol.59(47), pp.4183-4186
    Description: A new method was developed to prepare -sulfonyl amidine compounds through three-component reaction of aryl diazonium salts with sulfonamides and acetonitrile, in which, nitrilium ion intermediate, generated from the reaction of aryldiazonium salt with nitrile, was subsequently trapped by sulfonamides. A series of -sulfonyl amidine derivatives were synthesized by using various types of aryl diazonium salts, sulfonamides and nitriles. In addition, indolyl imine products could also be prepared by using indole as the nucleophile to trap nitrilium ion intermediate.
    Keywords: Amidine ; Nitrilium Ion ; Indolyl Imine Compound ; Three Component Reaction ; Chemistry
    ISSN: 0040-4039
    E-ISSN: 1873-3581
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  • 9
    In: Psychophysiology, March 2014, Vol.51(3), pp.285-289
    Description: Many studies have used the 300 as an index for cognitive processing and neurological/psychiatric disorders. Here, we combined the source separation and source localization methods to investigate the cortical origins of the 300 elicited in a facial attractiveness judgment task. For each participant, we applied second‐order blind identification () to continuous data to decompose the mixture of brain signals and noise. We then used the equivalent current dipole () models to estimate the centrality of the ‐recovered 300. We found that the models, consisting of dipoles in the frontal and posterior association cortices, account for 96.5 ± 0.5% of variance in the scalp projection of the component. Given that the recovered dipole activities in different brain regions share the same time course with different weights, we conclude that the 300 originates from synchronized activity between anterior and posterior parts of the brain.
    Keywords: Erp ; 300 ; Sobi ; Acial Attractiveness ; Ocalization
    ISSN: 0048-5772
    E-ISSN: 1469-8986
    E-ISSN: 15405958
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  • 10
    Language: English
    In: European Journal of Pharmacology, 05 January 2013, Vol.698(1-3), pp.137-144
    Description: Omentin-1, a new adipokine released from adipose tissue, is associated with several key aspects of metabolic syndrome such as insulin sensitivity. However, it is not known whether omentin-1 affects cancer cell growth. In this study, we studied the influence of omentin-1 on two types of human hepatocellular carcinoma cells: HepG2 and HuH-7 cells. Cell viability assay showed that omentin-1 (1 and 2 μg/ml) significantly inhibited the proliferation of HepG2 and HuH-7 cells. Both annexin+PI staining and TUNEL assay showed that omentin-1 induced apoptosis in these cells. Moreover, omentin-1 treatment upregulated protein levels of p53 and p21, a main transcriptional target of p53. Interestingly, omentin-1 did not affect p53 mRNA level. Further mechanism study showed that omentin-1 upregulated p53 protein level through decreasing p53 deacetylation and thereby increasing the stability of p53 protein. Using small interfering RNA (siRNA)-mediated knockdown, we found that Sirt1 deacetylase, but not histone deacetylase 1 (HDAC1), was required for the effect of omentin-1 on p53 deacetylation and cancer cell proliferation. In omentin-1 treated HepG2 cells, the bax/bcl-2 protein ratio was increased, while the caspase-3 signaling pathway was also activated. Omentin-1 triggered JNK signaling but not p38 and ERK1/2 signaling pathways. Collectively, our data suggests that the novel adipokine omentin-1 may contribute to the therapeutic strategy for hepatocellular carcinoma.
    Keywords: Adipokine ; Omentin-1 ; Hcc Cells ; P53 ; Acetylation ; Sirt1 ; Pharmacy, Therapeutics, & Pharmacology
    ISSN: 0014-2999
    E-ISSN: 1879-0712
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