Numerical Optimization of CNT Distribution in Functionally Graded CNT-Reinforced Composite Beams

This paper is concerned with the numerical optimization of the thickness-wise CNT (carbon nanotube) distribution in functionally graded CNT-reinforced composite (FG-CNTRC) beams to secure the structural safety. The FG-CNTRC in which CNTs are inserted according to the specific thickness-wise distribution pattern are extensively investigated for high-performance engineering applications. The mechanical behaviors of FG-CNTRC structures are definitely affected by the distribution pattern of CNTs through the thickness. Hence, the tailoring of suitable CNT distribution pattern is an essential subject in the design of FG-CNTRC structure for a given boundary and loading conditions. Nevertheless, the thickness-wise CNT distribution pattern has been assumed by several linear functions so that these assumed primitive patterns cannot appropriately respond to arbitrary loading and boundary conditions. In this context, this paper aims to introduce a numerical method for optimally tailoring the CNT distribution pattern of FG-CNTRC beams. As a preliminary stage, the effective stress is defined as the objective function and the layer-wise CNT volume fractions are chosen as the design variables. The exterior penalty-function method and golden section method are adopted for the optimization formulation, together with finite difference scheme for the design sensitivity analysis. The proposed optimization method is illustrated and validated through the benchmark experiments, such that it successfully provides an optimum CNT distribution which can significantly minimize the effective stress, with a stable and rapid convergence in the iterative optimization process

Urban land use spectral using high resolution imagery and GIS approach in sustaining urban planning spatial databases

Remote sensing technology is useful for urban planning due to its capability in examining detailed spectral characteristic of urban land uses. This study attempts to review a relevant studied have been done in identified an appropriate spectral for urban land use using high resolution remote sensing images and GIS approach. The detailed spectral for urban land uses consist of residential, industrial and commercial in metropolitan and city center urban hierarchy will be discussed. The segmentation techniques through object oriented and the use of field measurement was highlighted, at once demonstrates the usability of such infrastructure to facilitate further progress of remote sensing and GIS application in urban planning in Malaysia. Finally, a discussion of the needs for further research is presented

Preparation and characterisation of titanium dioxide produced from Ti-salt flocculated sludge in water treatment

During the past few years, titanium salts were investigated as alternative coagulants for the removal of organic matter of different molecular sizes in contaminated water. The flocculation efficiency of Ti-salt was comparable to those of FeCl3 and Al2(SO4)3 salts, commonly used coagulants. Incinerated sludge-TiO2 showed higher surface area and photocatalytic activity than commercially available TiO2. Metal-doped forms were produced by adding coagulant aids such as iron (Fe-), aluminium (Al-) and (Ca-) calcium salts during Ti-salt flocculation to increase pH. Ca- and Al- doped TiO2 showed very high photocatalytic activity compared to Fe-doped TiO2. When tested in a pilot scale plant for treatment of dye wastewater to check practical feasibility of the novel process, the removal ratio of the chemical oxygen demand was comparable to those of commonly used coagulants but the settling of sludge was faster. The TiO2 generated after sludge incineration showed a high photocatalytic activity for degradation of volatile organic compounds and increased the rate of hydrogen production by water photosplitting. TiCl4 coagulant and TiO2 produced from different water sources with different concentrations had low acute toxicity compared to heavy metals and commercial TiO2 when examined based on D. Magna mortality. This paper presents the production, characterisation and the photoactivity of TiO2 produced from Ti-salt flocculated sludge. Different case studies are discussed to highlighted recent advances in this field

Visible light responsive titanium dioxide (TiO<inf>2</inf>)

Titanium dioxide (TiO2) is one of the most researched semiconductor oxides that has revolutionised technologies in the field of environmental purification and energy generation. It has found extensive applications in heterogenous photocatalysis for removing organic pollutants from air and water and also in hydrogen production from photocatalytic water-splitting. Its use is popular because of its low cost, low toxicity, high chemical and thermal stability, But one of the critical limitations of TiO 2 as photocatalyst is its poor response to visible light. Several attempts have been made to modify the surface and electronic structures of TiO2 to enhance its activity in the visible light region such as noble metal deposition, metal ion loading, cationic and anionic doping and sensitisation, Most of the results improved photocatalytic performance under visible light irradiation. This paper attempts to review and update some of the information on the TiO2 photocatalytic technology and its accomplishment towards visible light region

Luteolin decreases IGF-II production and downregulates insulin-like growth factor-I receptor signaling in HT-29 human colon cancer cells

<p>Abstract</p> <p>Background</p> <p>Luteolin is a 3',4',5,7-tetrahydroxyflavone found in various fruits and vegetables. We have shown previously that luteolin reduces HT-29 cell growth by inducing apoptosis and cell cycle arrest. The objective of this study was to examine whether luteolin downregulates the insulin-like growth factor-I receptor (IGF-IR) signaling pathway in HT-29 cells.</p> <p>Methods</p> <p>In order to assess the effects of luteolin and/or IGF-I on the IGF-IR signaling pathway, cells were cultured with or without 60 μmol/L luteolin and/or 10 nmol/L IGF-I. Cell proliferation, DNA synthesis, and IGF-IR mRNA levels were evaluated by a cell viability assay, [³H]thymidine incorporation assays, and real-time polymerase chain reaction, respectively. Western blot analyses, immunoprecipitation, and <it>in vitro </it>kinase assays were conducted to evaluate the secretion of IGF-II, the protein expression and activation of IGF-IR, and the association of the p85 subunit of phophatidylinositol-3 kinase (PI3K) with IGF-IR, the phosphorylation of Akt and extracellular signal-regulated kinase (ERK)1/2, and cell division cycle 25c (CDC25c), and PI3K activity.</p> <p>Results</p> <p>Luteolin (0 - 60 μmol/L) dose-dependently reduced the IGF-II secretion of HT-29 cells. IGF-I stimulated HT-29 cell growth but did not abrogate luteolin-induced growth inhibition. Luteolin reduced the levels of the IGF-IR precursor protein and IGF-IR transcripts. Luteolin reduced the IGF-I-induced tyrosine phosphorylation of IGF-IR and the association of p85 with IGF-IR. Additionally, luteolin inhibited the activity of PI3K activity as well as the phosphorylation of Akt, ERK1/2, and CDC25c in the presence and absence of IGF-I stimulation.</p> <p>Conclusions</p> <p>The present results demonstrate that luteolin downregulates the activation of the PI3K/Akt and ERK1/2 pathways via a reduction in IGF-IR signaling in HT-29 cells; this may be one of the mechanisms responsible for the observed luteolin-induced apoptosis and cell cycle arrest.</p

Hydrogen production affected by Pt concentration on TiO <inf>2</inf> produced from the incineration of dye wastewater flocculated sludge using titanium tetrachloride

TiO 2 from the incineration of dye wastewater flocculated sludge using TiCl 4 coagulant was produced. Optimal catalyst amount and Pt-loading on TiO 2 were studied for the production of H 2 by photocatalytic reforming of methanol (6% vol.). On the other hand, BTSE (biologically treated sewage effluent) was flocculated using TiCl4 and produced sludge was incinerated to generate TiO 2 . TiO 2 was loaded with optimum Pt and added to the supernatant in a photocatalytic reactor to test the efficiency of using remaining organics as a “sacrificial reagent” for photocatalytic hydrogen production. Dissolved organic carbon (DOC) and molecular weight distribution (MWD) were measured for nanofiltration (NF) and TiCl 4 flocculation followed by photocatalysis. TiO 2 (from the incineration of BTSE flocculated sludge using TiCl4) was produced and loaded with 0.5% Pt. Results showed that the optimum concentration of TiO 2 (from dye wastewater) for H 2 production was 0.3 g/L, while the optimum amount of Pt was 0.5%. DOC and MWD removal was similar for the flocculation of BTSE followed by photocatalytic reaction and the NF process. Remaining organic compounds after flocculation could not be used as sacrificial reagent to induce H 2 production. Further investigations on studying the UV intensity and/or identifying organic/inorganic scavengers to inhibit H 2 production are underway. © 2010, Taylor & Francis Group, LLC

Sorghum cobalt analysis on not determined wave length with atomic absorption spectrophotometer on background correction mode

This study was to know the better wave length on measuring cobalt content in forage sorghum hybrid (Sorghum bicolor) with an atomic absorption spectrophotometer. The analysis was on background correction mode with three wave lengths; 240.8, 240.7 (determined wave length or recommended wave length) and 240.6 nm, respectively. The larger absorbance value on the 240.7 nm, apparently, it might be considered as a good wave length but the smaller background value was a more important factor for the analysis as was shown on 240.6 nm. Correlation coefficients between the values on 240.7 nm: 240.6 nm and between them (240.8 nm: 240.6 nm) were higher and this common 240.6 nm was considered the better wave length.Key words: Atomic absorption spectrophotometer; background correction mode, cobalt analysis, forage sorghum, not determined wave lengths