19672 research outputs found
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Malignant obstruction of superior vena cava: Endovascular stenting using Y-configuration stent in stent technique
No full textMalignant intrathoracic disease is the commonest cause of superior vena cava (SVC) obstruction. Life threatening SVC obstruction with intense dyspnoea requires urgent treatment. SVC stenting has been developed in recent years which results in rapid relief of the obstruction. The Y-configuration technique has been reported to provide support for all three limbs of the bifurcation to prevent restenosis. At present, there are limited reports on the use of Y-configuration stent in stent techniques for endovascular stenting in malignant SVC obstruction. We share our clinical experience of two patients who received balloon-mounted stents using this technique
Nonionic polyol esters as thinner and lubricity enhancer for synthetic-based drilling fluids
No full textThis study evaluates the performance of polyol esters as thinners and lubricity enhancers in invert emulsion synthetic-based drilling mud (SBM). Three types of polyol esters, namely pentaerythritol ester (PEE), trimethylolpropane ester (TMPE), and neopentyl glycol ester (NPGE), were prepared at various concentrations of 1, 2, and 3% (v/v) in SBM. The results showed that polyol esters reduced the rheological properties of the drilling mud, such as yield point and gel strength, after the hot rolling test at 135 °C. The rheology data was fitted to the Herschel-Bulkley model to describe the shear thinning behaviour of drilling mud. The model parameters showed that the polyol ester resulted in lower yield stress of SBM, which indicated lower forces are needed to initiate a fluid to move. Their relative effectiveness as a lubricity enhancer was evaluated by measuring the coefficient of friction (COF), wear scar diameter, and scar topography. It was found that polyol esters reduced the COF of SBM by 22% at a concentration of 1% (v/v). PEE provided the best friction reduction and anti-wear performance due to a higher number of the ester group and molecular weight, in comparison with NPGE and TMPE. The lubricity improvement for SBM is recently required by off-shore regulations
Regulatory incoherence in nutrition labelling of prepackaged food in ASEAN: What next?
No full textRegulatory heterogeneity (Pettman, 2013; USAID, 2013; Noraini, 2014) is identified as a challenge for increasing trade, harmonizing standards, and ultimately creating a single integrated Association of Southeast Asian Nations (ASEAN) market, which was a major objective in the formation of the ASEAN Economic Community (AEC) in 2015. One diverse technical regulation that governs the prepackaged food and beverage (PPF) industry is nutrition labelling. The labelling regulations across the AMS rest on the different International Guidelines followed by Member countries when preparing national regulations. Kasapila and Sharifudin (2011) point out that for nutrition labelling, Singapore, Malaysia, Brunei, Laos, Vietnam and Cambodia have followed the Codex1 guidelines in preparing their regulations. Conversely, Thailand and the Philippines, to some extent have adapted the United States (US) nutrition labelling guidelines. Even within those Member countries that adopt Codex, there are differences in the regulatory regime. Malaysia made nutrition labelling mandatory for energy, protein, carbohydrate, fat and total sugars for foods that are commonly consumed, and for various types of beverages in 2005 (AFBA, 2014; Kasapila and Sharifudin, 2011; see also Pettman, 2013). Nutrition labelling is also mandatory in the Philippines and Thailand, for certain food items. For other ASEAN countries that follow the Codex guidelines, nutrition labelling is voluntary; if nutrition and/or health claims are made on food packaging or if the food is for a special purpose (diabetic and fortified foods), nutrition labelling would then be mandatory
Composite liquid crystal-polymer electrolytes in dye-sensitised solar cells: effects of mesophase alkyl chain length
No full textThe doping of polymer electrolytes (PEs) with liquid crystal (LC) materials has been shown to improve the performance of dye-sensitised solar cells (DSSCs). This is achieved by promoting ionic conduction and increasing optical path length through multiple-light scattering within the photovoltaic devices. In LCs, it is well known that the length of the alkyl chain plays an important role since the LC morphology and mesophase stabilisation depend strongly on the alkyl group. In this work, liquid crystal-polymer composite electrolytes (LC-PEs) are prepared using nematic LCs with different alkyl chain lengths. The morphology of the LC-PEs is investigated and correlated with their electrical properties. Subsequently, DSSCs are prepared using the LC-PEs as a direct example of its application. It is shown that increasing the alkyl chain length of the LCs reduces the efficiency of the solar devices. The longer alkyl chains are speculated to intertwine, thus trapping the mobile ions and reducing the bulk ionic conductivity. For the same reason, longer alkyl chain LCs are thought to be unable to passivate the TiO2 surface through the adsorption of cyanobiphenyl groups and hence the higher probability of back recombination reaction between the electrons in TiO2 and PE
Composition, sources, and bioavailability of nitrogen in a longitudinal gradient from freshwater to estuarine waters
No full textNitrogen (N) transport from land to water is a dominant contributor of N in estuarine waters leading to eutrophication, harmful algal blooms, and hypoxia. Our objectives were to (1) investigate the composition of inorganic and organic N forms, (2) distinguish the sources and biogeochemical mechanisms of nitrate–N (NO3–N) transport using stable isotopes of NO3 − and Bayesian mixing model, and (3) determine the dissolved organic N (DON) bioavailability using bioassays in a longitudinal gradient from freshwater to estuarine ecosystem located in the Tampa Bay, Florida, United States. We found that DON was the most dominant N form (mean: 64%, range: 46–83%) followed by particulate organic N (PON, mean: 22%, range: 14–37%), whereas inorganic N forms (NOx–N: 7%, NH4–N: 7%) were 14% of total N in freshwater and estuarine waters. Stable isotope data of NO3 − revealed that nitrification was the main contributor (36.4%), followed by soil and organic N sources (25.5%), NO3 − fertilizers (22.4%), and NH4 + fertilizers (15.7%). Bioassays showed that 14 to 65% of DON concentrations decreased after 5-days of incubation indicating utilization of DON by microbes in freshwater and estuarine waters. These results suggest that despite low proportion of inorganic N forms, the higher concentrations and bioavailability of DON can be a potential source of N for algae and bacteria leading to water quality degradation in the estuarine waters
Preliminary development of porous aluminum via powder metallurgy technique
No full textPorous aluminum has been extensively studied, particularly in the field in which lightweight and high stiffness properties are essential. In this study, a preliminary investigation is performed to determine the optimum sintering temperature to develop porous aluminium by a powder metallurgy technique, using polymethylmethacrylate as a space holder. The effects of the sintering temperatures on the physical characteristics, oxidation level, microstructure and sintered density of the porous specimen are systematically evaluated. Based on the results, an increase in the sintering temperature from 580 °C to 600 °C changes the colour of the porous aluminum body from a silver-like colour to a gold-like colour, with some of the specimens encountering severe cracking, spalling and even collapsing. As such, the oxygen content is significantly increased from 0.45 wt.% to 2.14 wt. %, suggesting the oxidation phenomenon. In line with this, an obvious appearance of particle boundaries with less macro-pores formation is also observed. Additionally, the sintered density of the porous specimen is found to reduce from 1.305 g/cm3 to 0.908 g/cm3. Therefore, fabrication of the resultant porous aluminium at 580 °C is an ideal condition in this study, owing to the ideal combination of physical characteristics, microstructure, oxidation level and sintered density
Applied microfiber evanescent wave on ZnO nanorods coated glass surface towards temperature sensing
No full textA temperature sensor fabricated by using silica microfiber laid on glass surface coated with Zinc Oxide (ZnO) nanorods is reported. The silica microfiber was tapered for waist of 5 μm using flame brushing technique. The glass surface was grown with ZnO nanorods using hydrothermal method. A significant response to temperature changes from 40 °C to 120 °C was observed due to the change of ZnO refractive index on the glass surface resulting different light attenuation in the silica microfiber. Sensitivity increases by a factor of 3.1 in microfiber laid on the coated glass surface as compared to uncoated glass surface. As the temperature increases, the output power of the ZnO nanorods coated glass surface has decreasing linearly from −19.8 dB m to −23.32 dB m with linearity and resolution of 99.8% and 1.75 °C respectively. The proposed temperature sensor employs the dispersion of evanescent wave from silica microfiber and glass surface coated with ZnO nanorods which is easier to handle during synthesis process and sensing applications
Optimization of fat yield of bambangan (Mangifera pajang) kernel using response surface methodology and its antioxidant activities
No full textThe objectives of this study are to optimize the extraction of fat from bambangan kernel using response surface methodology and to determine its antioxidant activities and total phenolic contents (TPC). Bambangan kernel was also investigated to determine proximate and amino acids in a pursuit to identify an innovative fruit which could be exploited in other food applications. Results for proximate compositions of bambangan kernel indicates moisture contents of 8.9%, crude protein contents of 4.1%, ash contents of 2.8%, and carbohydrate contents of 72.9% on dry weight basis. The highest fat yield of bambangan kernel was found to be 11.0% with optimum parameters at solvent volume of 329.7 ml (n-hexane), samples weight of 27.0 g, and extraction time of 7.6 h. 2,2-Diphenyl-1-picryl-hydrazyl (DPPH) free radical scavenging ability of bambangan kernel powder and fat were found to be 60.6 ± 2.1 and 35.2 ± 2.1 mg TEAC/100 g, respectively. Moreover, the ferric reducing antioxidant power (FRAP) of bambangan kernel powder and fat were 150.6 ± 2.4 and 119.0 ± 6.3 mM/100 g, respectively. The TPC of bambangan kernel powder was 118.6 ± 1.9 mg GAE/g, whereas kernel fat was 94.1 ± 2.1 mg GAE/g. The DPPH radical scavenging and FRAP activities showed a strong correlation with TPC in both bambangan kernel powder and fat. The high TPC of bambangan kernel and its fat indicated that the kernels should be further utilized or processed to other food, nutraceutical or pharmaceutical products instead of discarded as waste
Inclusion of Curcumin in β-cyclodextrins as Potential Drug Delivery System: Preparation, Characterization and Its Preliminary Cytotoxicity Approaches
No full textThe development and application of organic based drug carrier in drug delivery system (DDSs) with greater efficacy and fewer side effects remains a significant challenge in modern scientific and medical research. The aim of current study was to evaluate the ability of β-cyclodextrin (β-CD) as drug delivery carrier to encapsulate Curcumin (CUR), a promising chemotherapeutic that exhibits low aqueous solubility and poor bioavailability forming inclusion complex by kneading method to enhance its delivery to cancer cells. Different methods and analysis such as Fourier Transform Infrared (FTIR) spectrometer, 1 H Nuclear Magnetic Resonance ( 1 H NMR), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Thermo-gravimetric Analysis (TGA) were employed to approve the successful formation of the inclusion complex where the aromatic ring of CUR has been encapsulated by the hydrophobic cavity of β-CD. UV absorption indicated that β-CD complex with CUR with an apparent formation constant of 1.09 × 10 -8 mol -1 dm -3 . Based on the data obtained by methylthiazole tetrazolium (MTT), β-CD showed that not only did it enhanced Curcumin delivery, but it also improved and promoted the anti-proliferative effect of CUR during the complexation rather than CUR alone on the MCF-7 human breast cancer cells at 24 h incubation period with IC 50 lower than that of Curcumin alone. The toxicities of the β-CD-CUR towards MCF-7 cells were also compared to the free tamoxifen, Curcumin and β-CD. This study provides a preliminary toxicity evaluation based on β-CD-CUR inclusion complex as potential delivery system towards the selected cancer cells
Comparative study of interfacial interaction between aromatic and aliphatic functional group in solder wettability
No full textThe effect of using different flux on wettability of Sn-Ag-Cu lead free solder were investigated. In this study, solder paste Sn-3.0Ag-0.5Cu (SAC305) was used by introducing two types of no-clean flux with different ingredients. The solders namely as SAC305-A and SAC305-B respectively. Then, the both solder paste manually printed on printed circuit board (PCB) using stencil printing and then reflowed at 260 °C temperature. Wettability of Sn-Ag-Cu solder using different flux was determined by contact angle measurement using Alicona ® IFM software. Results show the SAC305-A solder alloys have a good and better wettability with lower contact angle compared to SAC305-B. Functional groups of both solder flux was identified by FTIR analysis. Meanwhile XPS analysis was performed in characterizing the studied fluxes. It was found that no-clean flux solder with aromatic functional groups showed lower contact angle value and better wettability than aliphatic contained functional groups