Synthesis and biological activity of phthalimide‐based polymers containing 5‐fluorouracil

The attachment of anticancer agents to polymers is a promising approach towards reducing the toxic side‐effects and retaining the potent antitumour activity of these agents. A new tetrahydrophthalimido monomer containing 5‐fluorouracil (ETPFU) and its homopolymer and copolymers with acrylic acid (AA) and with vinyl acetate (VAc) have been synthesized and spectroscopically characterized. The ETPFU contents in poly(ETPFU‐co‐AA) and poly(ETPFU‐co‐VAc) obtained by elemental analysis were 21 mol% and 20 mol%, respectively. The average molecular weights of the polymers determined by gel permeation chromatography were as follows: M_n = 8900 g mol^?1, M_w = 13 300 g mol^?1, M_w/M_n = 1.5 for poly(ETPFU); M_n = 13 500 g mol^?1, M_w = 16 600 g mol^?1, M_w/M_n = 1.2 for poly(ETPFU‐co‐AA); M_n = 8300 g mol^?1, M_w = 11 600 g mol^?1, M_w/M_n = 1.4 poly(ETPFU‐co‐VAc). The in vitro cytotoxicity of the compounds against FM3A and U937 cancer cell lines increased in the following order: ETPFU > 5‐FU > poly(ETPFU) > poly(ETPFU‐co‐AA) > poly(ETPFU‐co‐VAc). The in vivo antitumour activities of all the polymers in Balb/C mice bearing the sarcoma 180 tumour cell line were greater than those of 5‐FU and monomer at the highest dose (800 mg kg^?1). © 2002 Society of Chemical Industry     

Molecularly Targeted Agents as Radiosensitizers in Cancer Therapy—Focus on Prostate Cancer

As our understanding of the molecular pathways driving tumorigenesis improves and more druggable targets are identified, we have witnessed a concomitant increase in the development and production of novel molecularly targeted agents. Radiotherapy is commonly used in the treatment of various malignancies with a prominent role in the care of prostate cancer patients, and efforts to improve the therapeutic ratio of radiation by technologic and pharmacologic means have led to important advances in cancer care. One promising approach is to combine molecularly targeted systemic agents with radiotherapy to improve tumor response rates and likelihood of durable control. This review first explores the limitations of preclinical studies as well as barriers to successful implementation of clinical trials with radiosensitizers. Special considerations related to and recommendations for the design of preclinical studies and clinical trials involving molecularly targeted agents combined with radiotherapy are provided. We then apply these concepts by reviewing a representative set of targeted therapies that show promise as radiosensitizers in the treatment of prostate cancer.     

Nitroxide-mediated polymerization of styrene initiated from the surface of fumed silica. Comparison of two synthetic routes

Nitroxide-mediated free radical polymerization of styrene was performed from 13 nm diameter fumed silica in two steps. First, an alkoxyamine, based on N-tert-butyl-N-(1-diethylphosphono-2,2-dimethylpropyl) nitroxide (DEPN) was covalently attached onto silica. Polystyrene chains with controlled molecular weights and narrow polydispersities were then grown from the alkoxyamine-functionalized nanoparticles surface in the presence of a ‘free’ sacrificial styrylDEPN alkoxyamine. Two strategies were investigated in order to immobilize the alkoxyamine initiator on the silica surface. In a first route, we synthesized a unimolecular alkoxyamine initiator carrying triethoxysilyl end groups reactive towards the silica surface. In a second route, the alkoxylamine was formed in situ by the simultaneous reaction of a polymerizable acryloxy propyl trimethoxysilane (APTMS), azobisisobutyronitrile (AIBN) and DEPN used as radical trap. In both cases, the grafting of both the initiator and the polystyrene chains was characterized and quantified by several techniques which allowed us to evaluate and compare the two strategies.     

A comparative study on the electrical and mechanical behaviour of multi‐walled carbon nanotube composites prepared by diluting a masterbatch with various types of polypropylenes

Polypropylene (PP) nanocomposites with multi‐walled carbon nanotubes (CNT) were produced by a small‐scale masterbatch melt dilution technique using five PP differing in melt flow index (MFI) and degree of maleination. PP used in a masterbatch has MFI = 12 (PP₁₂), the others used PP which have MFI = 2 or MFI = 8. The state of CNT dispersion as assessed by melt rheological and morphological investigations indicated a better dispersion when using unmodified PP with MFI = 8 (PP₈) and the masterbatch's PP₁₂. Electrical conductivity results showed nanotube percolation at contents between 1.1 and 2.0 vol %, whereas lower values were obtained for the matrices with the best dispersion, i.e., PP₈ and PP₁₂. The dependencies of the relative Young's modulus on the CNT content showed that the maleinization improved the interfacial interactions between the components, especially in the case of maleated PP with MFI = 8 (PP‐MA₈), but the better dispersion was prevented by the incompatibility between polar groups of PP‐MA and the nonpolar origin masterbatch PP₁₂. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Fabrication and Testing of Oxide/Oxide Microcomposites with Monazite and Hibonite as Interlayers

Oxide/oxide microcomposites were fabricated and tested to evaluate the effectiveness of monazite (LaPO₄) and hibonite (CaAl₁₂O₁₉) as interlayers in sapphire-reinforced Al₂O₃-matrix composites. For interlayer thicknesses of 0.3-0.5 µm, both interlayers showed evidence of crack deflection; however, debond lengths in hibonite-coated specimens were limited to just a small fraction of the fiber diameter. Monazite-coated specimens showed multiple matrix cracks and extensive debonding at the coating/matrix interface. Composite strengths were relatively high for both coatings, considering the fiber strength degradation during processing. The strengths were greater than the calculated matrix cracking stresses. However, the mean strengths were not significantly different from those of the control specimens, although coated composites had higher Weibull moduli. The lack of difference in strength is attributed to porosity in the matrix. The results imply that matrix density needs to be >85% to evaluate novel interface strategies reliably.     

中间包等离子加热和电磁搅拌复合技术的开发与使用

在连铸过程中,严格的钢水温度控制是保证连铸坯质量的前提,所以中包温度控制技术成为炼钢研究的方向之一。其中,中包等离子加热技术由于控制灵活,设备简单和清洁无污染具有广阔的应用前景。与感应加热相比,等离子加热在中包包型设计和维护成本上具有明显的优势。另外一面,与感应加热90%的加热效率相比,等离子加热仅有60%的加热效率。因此,如何提高等离子加热效率成为制约其发展的关键因素。ABB对于电磁搅拌和等离子加热相结合的方案做了大量的数值研究分析。结果显示,仅使用等离子加热,那么加热室的上部钢液由于浮力作用而滞流,导致传热效率低下,这是由于等离子加热形成了巨大的温度梯度造成的。结合使用EMS,加热室内的钢液以0.2～0.4 m/s的速度旋流,这加速了中包内钢水的对流传热,使得中包内的钢液温度均匀化,减小了中包水口处的温度波动,提高了等离子加热的热效率。同时,通过等离子加热和电磁搅拌相结合的方式能促进夹杂物上浮,达到净化钢水的作用。     

Electrochemical nitrite nanosensor developed with amine- and sulphate-functionalised polystyrene latex beads self-assembled on polyaniline

Aniline doped with polyvinyl sulphonate (PV-SO₃⁻) was electropolymerised on screen printed carbon (SPCE) and glassy carbon (GCE) electrodes. Then nano-structured polystyrene (PS_NP) latex beads functionalised with amine (PS_NP-NH₂) and sulphate (PS_NP-OSO₃⁻) were self-assembled on the modified SPCE and GCE. The resultant polyaniline nanocomposites (PANI|PS_NP-NH₂ or PANI|PS_NP-OSO₃⁻) were characterised by cyclic voltammetry (CV), UV-vis spectroscopy and scanning electron microscopy (SEM). Brown-Anson analysis of the multi-scan rate CV responses of the various PANI films gave surface concentrations of the order of 10⁻⁸ mol cm⁻². UV-vis spectra of the PANI films dissolved in dimethyl sulphoxide showed typical strong absorbance maxima at 480 and 740 nm associated with benzenoid π-π* transition and quinoid excitons of polyaniline, respectively. The SEM images of the PANI nanocomposite films showed cauliflower-like structures that are <100 nm in diameter. When applied as electrochemical nitrite sensor, sensitivity values of 60, 40 and 30 μA/mM were obtained for electrode systems containing PANI|PS_NP-NH₂, PANI and PANI|PS_NP-SO₃⁻, respectively. The corresponding limits of detection of the sensors were 7.4, 9.2 and 38.2 μM NO₂⁻.     

Galvanic corrosion of aluminium alloy members of bridge guiderails under severe atmospheric exposure conditions

ABSTRACT

Aluminium alloys are nowadays preferred as materials for bridge guiderails especially for bridges connecting oceanic islands or spanning inlets due to their inherent corrosion resistance. But because of the limited mechanical strength of aluminium alloy, fasteners of guiderail members are made from steel materials. It has been found that contact between bare steel fasteners and aluminium alloy members can cause galvanic corrosion in the aluminium alloy. Research was carried out to investigate the capability of different surface treatments on fasteners and aluminium alloy members to inhibit galvanic corrosion under atmospheric exposure for periods of one and three years. It was found, among other results, that stainless steel fasteners treated with zinc flake coating were the most effective inhibitors of galvanic corrosion on aluminium alloy members.     

TNFα-Induced LDL Cholesterol Accumulation Involve Elevated LDLR Cell Surface Levels and SR-B1 Downregulation in Human Arterial Endothelial Cells

Excess lipid droplets are frequently observed in arterial endothelial cells at sites of advanced atherosclerotic plaques. Here, the role of tumor necrosis factor alpha (TNFα) in modulating the low-density lipoprotein (LDL) content in confluent primary human aortic endothelial cells (pHAECs) was investigated. TNFα promoted an up to 2 folds increase in cellular cholesterol, which was resistant to ACAT inhibition. The cholesterol increase was associated with increased ¹²⁵I-LDL surface binding. Using the non-hydrolysable label, Dil, TNFα could induce a massive increase in Dil-LDL by over 200 folds. The elevated intracellular Dil-LDL was blocked with excess unlabeled LDL and PCSK9, but not oxidized LDL (oxLDL), or apolipoprotein (apoE) depletion. Moreover, the TNFα-induced increase of LDL-derived lipids was elevated through lysosome inhibition. Using specific LDLR antibody, the Dil-LDL accumulation was reduced by over 99%. The effects of TNFα included an LDLR cell surface increase of 138%, and very large increases in ICAM-1 total and surface proteins, respectively. In contrast, that of scavenger receptor B1 (SR-B1) was reduced. Additionally, LDLR antibody bound rapidly in TNFα-treated cells by about 30 folds, inducing a migrating shift in the LDLR protein. The effect of TNFα on Dil-LDL accumulation was inhibited by the antioxidant tetramethythiourea (TMTU) dose-dependently, but not by inhibitors against NF-κB, stress kinases, ASK1, JNK, p38, or apoptosis caspases. Grown on Transwell inserts, TNFα did not enhance apical to basolateral LDL cholesterol or Dil release. It is concluded that TNFα promotes LDLR functions through combined increase at the cell surface and SR-B1 downregulation.