148 resultados para Fluorine containing polymers
Resumo:
Background: Radiation-induced skin reaction (RISR) is one of the most common and distressing side effects of radiotherapy in patients with cancer. It is featured with swelling, redness, itching, pain, breaks in skin, discomfort, and a burning sensation. There is a lack of convincing evidence supporting any single practice in the prevention or management of RISR. Methods/Designs: This double-blinded randomised controlled trial aims to investigate the effects of a natural oil-based emulsion containing allantoin (as known as Moogoo Udder Cream®) versus aqueous cream in reducing RISR, improving pain, itching and quality of life in this patient group. One group will receive Moogoo Udder Cream®. Another group will receive aqueous cream. Outcome measures will be collected using patient self-administered questionnaire, interviewer administered questionnaire and clinician assessment at commencement of radiotherapy, weekly during radiotherapy, and four weeks after the completion of radiotherapy. Discussion: Despite advances of radiologic advances and supportive care, RISR are still not well managed. There is a lack of efficacious interventions in managing RISR. While anecdotal evidence suggests that Moogoo Udder Cream® may be effective in managing RISR, research is needed to substantiate this claim. This paper presents the design of a double blind randomised controlled trial that will evaluate the effects of Moogoo Udder Cream® versus aqueous cream for managing in RISR in patients with cancer. Trial registration: ACTRN 12612000568819
Resumo:
The crystal structures of the rubidium and caesium complexes with 2-aminobenzenesulfonic acid (orthanilic acid), [Rb4(C6H6NO3S)4(H2O)]n (1) and [Cs(C6H6NO3S)]n (2) and have been determined at 200 K. Complex 1 has a repeating unit comprising four independent and different Rb coordination centres, (RbO8), (RbO7), (RbN2O4) and (RbO10), each having irregular stereochemistry and involving a number of bidentate chelate sulfonate-O,O’-metal and bridging interactions, giving a two-dimensional polymeric layered structure. Anhydrous complex 2 is also polymeric with the irregular (CsO7) coordination polyhedron comprising six sulfonate oxygen donors from three separate bidentate chelate sulfonate ligands and one monodentate bridging sulfonate oxygen, giving a two-dimensional layered structure.
Resumo:
The presence of large number of single-phase distributed energy resources (DERs) can cause severe power quality problems in distribution networks. The DERs can be installed in random locations. This may cause the generation in a particular phase exceeds the load demand in that phase. Therefore the excess power in that phase will be fed back to the transmission network. To avoid this problem, the paper proposes the use of distribution static compensator (DSTATCOM) that needs to be connected at the first bus following a substation. When operated properly, the DSTATCOM can facilitate a set of balanced current flow from the substation, even when excess power is generated by DERs. The proposals are validated through extensive digital computer simulation studies using PSCAD and MATLAB.
Resumo:
It is of great importance to develop multifunctional bioactive scaffolds, which combine angiogenesis capacity, osteostimulation, and antibacterial properties for regenerating lost bone tissues. In order to achieve this aim, we prepared copper (Cu)-containing mesoporous bioactive glass (Cu-MBG) scaffolds with interconnective large pores (several hundred micrometer) and well-ordered mesopore channels (around 5 nm). Both Cu-MBG scaffolds and their ionic extracts could stimulate hypoxia-inducible factor (HIF)-1a and vascular endothelial growth factor(VEGF) expression in human bone marrow stromal cells(hBMSCs). In addition, both Cu-MBG scaffolds and their ionic extracts significantly promoted the osteogenic differentiation of hBMSCs by improving their bone-related gene expression (alkaline phosphatase (ALP), osteopontin(OPN) and osteocalcin (OCN)). Furthermore, Cu-MBG scaffolds could maintain a sustained release of ibuprofen and significantly inhibited the viability of bacteria. This study indicates that the incorporation of Cu2þ ions into MBG scaffolds significantly enhances hypoxia-like tissue reaction leading to the coupling of angiogenesis and osteogenesis. Cu2þ ions play an important role to offer the multifunctional properties of MBG scaffold system. This study has demonstrated that it is possible to develop multifunctional scaffolds by combining enhanced angiogenesis potential, osteostimulation, and antibacterial properties for the treatment of large bone defects.
Resumo:
Epidermal growth factor (EGF) activation of the EGF receptor (EGFR) is an important mediator of cell migration, and aberrant signaling via this system promotes a number of malignancies including ovarian cancer. We have identified the cell surface glycoprotein CDCP1 as a key regulator of EGF/EGFR-induced cell migration. We show that signaling via EGF/EGFR induces migration of ovarian cancer Caov3 and OVCA420 cells with concomitant up-regulation of CDCP1 mRNA and protein. Consistent with a role in cell migration CDCP1 relocates from cell-cell junctions to punctate structures on filopodia after activation of EGFR. Significantly, disruption of CDCP1 either by silencing or the use of a function blocking antibody efficiently reduces EGF/EGFR-induced cell migration of Caov3 and OVCA420 cells. We also show that up-regulation of CDCP1 is inhibited by pharmacological agents blocking ERK but not Src signaling, indicating that the RAS/RAF/MEK/ERK pathway is required downstream of EGF/EGFR to induce increased expression of CDCP1. Our immunohistochemical analysis of benign, primary, and metastatic serous epithelial ovarian tumors demonstrates that CDCP1 is expressed during progression of this cancer. These data highlight a novel role for CDCP1 in EGF/EGFR-induced cell migration and indicate that targeting of CDCP1 may be a rational approach to inhibit progression of cancers driven by EGFR signaling including those resistant to anti-EGFR drugs because of activating mutations in the RAS/RAF/MEK/ERK pathway.
Resumo:
The selection of appropriate analogue materials is a central consideration in the design of realistic physical models. We investigate the rheology of highly-filled silicone polymers in order to find materials with a power-law strain-rate softening rheology suitable for modelling rock deformation by dislocation creep and report the rheological properties of the materials as functions of the filler content. The mixtures exhibit strain-rate softening behaviour but with increasing amounts of filler become strain-dependent. For the strain-independent viscous materials, flow laws are presented while for strain-dependent materials the relative importance of strain and strain rate softening/hardening is reported. If the stress or strain rate is above a threshold value some highly-filled silicone polymers may be considered linear visco-elastic (strain independent) and power-law strain-rate softening. The power-law exponent can be raised from 1 to ~3 by using mixtures of high-viscosity silicone and plasticine. However, the need for high shear strain rates to obtain the power-law rheology imposes some restrictions on the usage of such materials for geodynamic modelling. Two simple shear experiments are presented that use Newtonian and power-law strain-rate softening materials. The results demonstrate how materials with power-law rheology result in better strain localization in analogue experiments.
Resumo:
Molecular dynamics simulations were carried out on single chain models of linear low-density polyethylene in vacuum to study the effects of branch length, branch content, and branch distribution on the polymer’s crystalline structure at 300 K. The trans/gauche (t/g) ratios of the backbones of the modeled molecules were calculated and utilized to characterize their degree of crystallinity. The results show that the t/g ratio decreases with increasing branch content regardless of branch length and branch distribution, indicating that branch content is the key molecular parameter that controls the degree of crystallinity. Although t/g ratios of the models with the same branch content vary, they are of secondary importance. However, our data suggests that branch distribution (regular or random) has a significant effect on the degree of crystallinity for models containing 10 hexyl branches/1,000 backbone carbons. The fractions of branches that resided in the equilibrium crystalline structures of the models were also calculated. On average, 9.8% and 2.5% of the branches were found in the crystallites of the molecules with ethyl and hexyl branches while C13 NMR experiments showed that the respective probabilities of branch inclusion for ethyl and hexyl branches are 10% and 6% [Hosoda et al., Polymer 1990, 31, 1999–2005]. However, the degree of branch inclusion seems to be insensitive to the branch content and branch distribution.
Resumo:
Orebodies at Ok Tedi contain a number of different fluorine bearing minerals. Some of these minerals report to concentrate and are responsible for the presence of the penalty element, fluorine, within the concentrate. Previous analytical work has tended to examine geological samples for content, rather than determine the metallurgical behaviour of the different mineralogical species. This investigation utilised X-Ray Diffraction combined with Scanning Electron Microscope/Electron Microprobe to identify the fluorine bearing minerals in flotation test products. Seven fluorine bearing minerals were identified, viz., talc, phlogopite, amphibole (tremolite and actinolite), sphene, apatite, biotite and clay. Talc was found exclusively in the skarn ore type. Phlogopite and amphiboles (tremolite and actinolite) were found to occur in both skarn and porphyry ores, while sphene, apatite, biotite and clay were found only in the porphyry ores. Of the fluorine bearing minerals observed, only talc exhibited natural hydrophobicity to any significant degree. Phlogopite and the amphibole minerals were found to be hydrophillic, whilst the remaining minerals occurred in insufficient quantities to determine the flotation behaviour. Ok Tedi copper concentrate fluorine content prior to skarn ore treatment in the mill (typically 350ppm) was previously identified as deriving from phlogopite, while talc was believed to be the source of intermittent high concentrate fluorine contents when skarn ores were treated. This paper provides supporting evidence for this belief, and reports the nature of fluorine bearing mineral flotation behaviour.
Resumo:
The effects of electron irradiation on NiO-containing solid solution systems are described. Partially hydrated NiO solid solutions, e. g. , NiO-MgO, undergo surface reduction to Ni metal after examination by TEM. This surface layer results in the formation of Moire interference patterns.
Resumo:
Production of nanofibrous polyacrylonitrile/calcium carbonate (PAN/CaCO3) nanocomposite web was carried out through solution electrospinning process. Pore generating nanoparticles were leached from the PAN matrices in hydrochloric acid bath with the purpose of producing an ultimate nanoporous structure. The possible interaction between CaCO3 nanoparticles and PAN functional groups was investigated. Atomic absorption method was used to measure the amount of extracted CaCO3 nanoparticles. Morphological observation showed nanofibers of 270–720 nm in diameter containing nanopores of 50–130 nm. Monitoring the governing parameters statistically, it was found that the amount of extraction (ε) of CaCO3was increased when the web surface area (a) was broadened according to a simple scaling law (ε = 3.18 a0.4). The leaching process was maximized in the presence of 5% v/v of acid in the extraction bath and 5 wt % of CaCO3 in the polymer solution. Collateral effects of the extraction time and temperature showed exponential growth within a favorable extremum at 50°C for 72 h. Concentration of dimethylformamide as the solvent had no significant impact on the extraction level.
Resumo:
The interaction of water with the fluorine-covered (001) surface of anatase titanium dioxide (TiO2) has been studied within the framework of density functional theory (DFT). Our results show that water dissociation is unfavorable due to repulsive interactions between surface fluorine and oxygen. We also found that the reaction of hydrofluoric acid with a surface hydroxyl group to form a surface Ti–F bond is exothermic, while the removal of fluorine from the surface needs additional energy of about half an eV. Therefore, water molecules are predicted to remain intact at the interface with the F-terminated anatase (001).
Resumo:
Successive alkalinity producing systems (SAPSs) are widely used for treating acid mine drainage (AMD) and alleviating clogging commonly occurring in limestone systems due to an amorphous ferric precipitate. In this study, iron dust, bone char, micrite and their admixtures were used to treat arseniccontaining AMD. A particular interest was devoted to arsenic removal performance, mineralogical constraints on arsenic retention ability and permeability variation during column experiment for 140 days. The results showed that the sequence of the arsenic removal capacity was as follows: bone char > micrite > iron dust. The combination of 20% v/v iron dust and 80% v/v bone char/micrite columns can achieve better hydraulic conductivity and phosphorus-retention capacity than single micrite and bone char columns. The addition of iron dust created reductive environment and resulted in the transformation of coating material from colloidal phase to secondary mineral phase, such as green rust and phosphoerrite, which obviously ameliorates hydraulic conductivity of systems. The sequential extraction experiments indicated that the stable fractions of arsenic in columns were enhanced with help of iron dust compared to single bone char and micrite columns. A combination of iron dust and micrite/bone char represented a potential SAPS for treating As-containing AMD.
Resumo:
Severe power quality problems can arise when a large number of single-phase distributed energy resources (DERs) are connected to a low-voltage power distribution system. Due to the random location and size of DERs, it may so happen that a particular phase generates excess power than its load demand. In such an event, the excess power will be fed back to the distribution substation and will eventually find its way to the transmission network, causing undesirable voltage-current unbalance. As a solution to this problem, the article proposes the use of a distribution static compensator (DSTATCOM), which regulates voltage at the point of common coupling (PCC), thereby ensuring balanced current flow from and to the distribution substation. Additionally, this device can also support the distribution network in the absence of the utility connection, making the distribution system work as a microgrid. The proposals are validated through extensive digital computer simulation studies using PSCADTM
Resumo:
A controlled layer of multi-wall carbon nanotubes (MWCNT) was grown directly on top of fluorine-doped tin oxide (FTO) glass electrodes as a surface modifier for improving the performance of polymer solar cells. By using low-temperature chemical vapor deposition with short synthesis times, very short MWCNTs were grown, these uniformly decorating the FTO surface. The chemical vapor deposition parameters were carefully refined to balance the tube size and density, while minimizing the decrease in conductivity and light harvesting of the electrode. As created FTO/CNT electrodes were applied to bulk-heterojunction polymer solar cells, both in direct and inverted architecture. Thanks to the inclusion of MWCNT and the consequent nano-structuring of the electrode surface, we observe an increase in external quantum efficiency in the wavelength range from 550 to 650 nm. Overall, polymer solar cells realized with these FTO/CNT electrodes attain power conversion efficiency higher than 2%, outclassing reference cells based on standard FTO electrodes.