Peroxide crosslinking of rigid poly(vinyl chloride)

Peroxide crosslinking of unplasticized poly(vinyl chloride) with trimethylolpropane trimethacrylate was investigated. Formulations used in this work contained a nontoxic lead‐free stabilizer and showed good color and heat stability. The samples were examined by differential scanning calorimetry, and their tensile properties were measured at room temperature and at 130°C. Gel content or tetrahydrofuran‐insoluble material was measured as an indication of crosslinking. It was shown that premature crosslinking could be avoided during processing and that 190°C was the optimum processing temperature for maximum gel content. The residual unsaturation was monitored by using FTIR spectroscopy. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers     

RE-READING SINGAPORE’S “BLACK AND WHITE” ARCHITECTURAL HERITAGE: THE AESTHETIC AFFECTS AND AFFECTATIONS OF ADAPTIVE REUSE

Colonial-period military estates in Singapore are being gentrified for adaptive reuse producing high-end hospitality and retail venues for expatriate and tourist consumption. These include the feted “Black and White” residential enclaves synonymous with Singapore’s tropical aesthetic. But underlying this reinvention is a disturbing history of wartime repurposing under the Japanese Imperial Army, which temporarily destabilised the meanings and representations of these buildings. The seemingly undisturbed architectural typologies of barracks, bungalows and timber huts were backdrops to war, military occupation and captivity. This paper explores how the aesthetic affects and affectations that accompany adaptive reuse may conceal or disclose unsettling histories. It contrasts contemporary celebration of these revitalised historical neighbourhoods with their very different representation by wartime captives.     

Solvent and Extraction Conditions Control the Assayable Phenolic Content and Antioxidant Activities of Seeds of Black Beans,Canola and Millet

The effects of extraction solvent and conditions on the total phenolic content (TPC) and antioxidant activity of black beans, canola and foxtail millet were investigated. The antioxidant activity was assayed using 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging activity (DRSA) and oxygen radical absorbance capacity (ORAC). Four solvent systems, namely 70 % acetone, 80 % ethanol, 80 % methanol and a mixture of acetone/methanol/water (7:7:6, v/v/v) were used. The extraction methods adopted in this study included refluxing, homogenization, cold extraction and sonication. The TPC as measured using the Folin Ciocalteu's method were 12.35–28.39, 2.43–16.73, and 1.78–5.06 µmol catechin equivalents/g dry matter (dm) for canola, black beans and foxtail millet, respectively. Aqueous acetone afforded the highest TPC for black beans and canola. Within the same solvent system used, the TPC, DRSA and ORAC obtained from different extraction techniques differed for black beans, canola and foxtail millet. The results demonstrated that the solvent system as well as method influenced the extraction of phenolic compounds and their antioxidant activities, depending on the type of matrix in which phenolics were embedded.     

Encampments: Spatial Taxonomies of Sri Lanka's Civil War

The escalation of human displacements occurring during the twenty-first century has seen the emergence of humanitarian relief accommodation as a new architectural type worthy of close analysis. Yet, these isolated physical phenomena and related design interventions alone are inadequate for theorising spatial violence. This paper broadens the analysis of camps to encompass notions of “encampment” related to war, militarisation, and urban security, using dispossession, eviction, and refugee movement as its empirical lens. Focusing on two examples from Colombo, Sri Lanka, where the spatial violence of radical human displacement is domesticated as everyday urban phenomena, this paper links the wartime emergence of camp environments, of temporal urban spaces, and the militarisation of the public sphere to economic liberalisation and political change.     

Antifeedants in the Feces of the Pine Weevil Hylobius abietis: Identification and Biological Activity

Egg-laying females of the pine weevil, Hylobius abietis (L.), regularly deposit feces adjacent to each egg. Egg cavities are gnawed in the bark of roots of recently dead conifer trees. After egg deposition, the cavity is sealed by feces and a plug of bark fragments. Root bark containing egg cavities with feces is avoided as food by pine weevils, which indicates the presence of natural antifeedants. Here we present the first results of the isolation and chemical analyses of antifeedant compounds in the feces of H. abietis. In feeding bioassays, methanol extracts of the feces revealed strong antifeedant properties. Methanol extracts were fractionated by medium-pressure liquid chromatography and the antifeedant effects were mainly found in the fractions of highest polarity. Volatile compounds in the active fractions were identified by gas chromatography–mass spectrometry (GC–MS) and the nonvolatile compounds were characterized by pyrolysis–GC–MS. Based on mass spectra, a number of compounds with various chemical structures were selected to be tested for their antifeedant properties. Antifeedant effects were found among compounds apparently originating from lignin: e.g., a methylanisol, guaiacol, veratrol, dihydroxybenzenes, and dihydroconiferyl alcohol. A weak effect by fatty acid derivatives was found. The types of naturally occurring antifeedant compounds identified in this study may become useful for the protection of planted conifer seedlings against damage by H. abietis.     

Oxidative Stability of Cashew Oils from Raw and Roasted Nuts

Cashew nut oils, extracted from raw and roasted whole cashew nuts, were examined for their fatty acid composition, color change and oxidative stability. Fatty acids were analyzed using gas chromatography, and a spectrophotometric method was used to determine the color changes of the resultant oils. Oxidative stability was determined under accelerated oxidation conditions by employing conjugated diene (CD) and thiobarbituric acid reactive substances (TBARS) assays. The contents of monounsaturated (MUFA), polyunsaturated (PUFA) and saturated (SAFA) fatty acids were 61, 17 and 21%, respectively. Oleic acid was the major MUFA whereas linoleic acid was the main PUFA present in cashew nut oils. Oxidative stability of the oil as determined by CD values after 72 h of storage under Schall oven condition at 60 °C was 1.08 and 0.65 for the raw and high temperature roasted cashew nut, respectively. The TBARS values, expressed as malondialdehyde equivalents decreased with increasing roasting temperature. Thus roasting of whole cashew nuts improved the oxidative stability of the resultant nut oils.     

Effect of processing on the antioxidant activity of millet grains

Millets are generally dehulled and subjected to a hydrothermal treatment before consumption, thus the hulls can be used as a potential source of antioxidants. Several millet grains, namely kodo, finger (Ravi), finger (local), proso, foxtail, little and pearl millet were studied. Antioxidant activities of phenolic extracts obtained from whole grains, as well as their corresponding dehulled and cooked grains and hulls were studied for their total phenolic content (TPC), radical scavenging capacity, and antioxidant activity in a β-carotene/linoleate emulsion. The phenolics present in whole grains were identified and quantified using HPLC and HPLC/MS and results were expressed as total for each of the phenolic groups. The TPC ranged from 2 to 112 μmol ferulic acid equivalents/g defatted meal. All varieties exhibited effective inhibition of 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl, peroxyl and superoxide radicals. Dehulling and cooking affected the TPC and radical scavenging and antioxidant activities of the grains, depending on the variety. In general, the antioxidant activity of phenolic extracts was in the order of hull > whole grain > dehulled grain > cooked dehulled grain With the exception of the two finger millet varieties, hulls of other millet grains had high TPC, thus demonstrating their superior antioxidant activity. Hydroxybenzoic acids, hydroxycinnamic acids and flavonoids in whole grains were identified as contributors to the observed effects. Therefore, dehulling of grain and hydrothermal treatments affect the phenolic content and antioxidant potential of millet grains.     

Effects of crosslinked elastomer particles on heterogeneous nucleation of isotactic PP in dynamically vulcanized EPDM/PP and EOC/PP blends

The isothermal and non-isothermal crystallizations of PP in neat form and in the TPVs EPDM/PP and EOC/PP were investigated using differential scanning calorimetry (DSC). The crystallization of PP was systematically studied by fitting mathematical models, and was later confirmed by X-ray diffraction (XRD) and by scanning electron microscopy (SEM). The experiments revealed that crosslinked elastomer particles first accelerated the primary nucleation of the PP matrix, acting effectively as a nucleating agent that reduces the induction time while increasing the nucleation efficiency. In the secondary nucleation regime (growth of spherulites), the crosslinked elastomer particles enhanced crystal growth rate, reducing the nucleation energy contribution from PP chain folding. Moreover, the crosslinked elastomer particles increased the final thickness of PP lamellae from that of neat PP, and this was corroborated by the XRD results. On comparing the two types of elastomer, it was found that the EOC particles were more effective in heterogeneous cell nucleation than the EPDM particles. The morphological study by SEM revealed completely altered PP spherulite size and shape, as well as their altered distribution, affected by heterogeneous nucleation effects of the crosslinked elastomer particles.     

The corrosion of mild steel in 0.01M, 1M and 3M HCl

The corrosion of mild steel has been studied in HCl of concentrations 3M, 1M and 0.01M. The anodic reaction order with respect to OH^? ion is 0.5 ± 0.2. A reaction mechanism with an intermediate following the Temkin adsorption isotherm has been proposed to explain the observed kinetic parameters     

Studies on process parameters for chlorine dioxide production using IrO2 anode in an un-divided electrochemical cell

Chlorine dioxide is potentially a powerful oxidant with environmentally compatible application in several strategic areas relating to pollution control typically for water disinfection, and its sustained production is a key factor for its successful application. Although increased attention has been paid for on-line chlorine dioxide generation by several chemical and electrochemical methods, the details are mostly confined as patents. We studied in this work the electrochemical generation of chlorine dioxide from an un-buffered solution of sodium chlorite and sodium chloride mixture in an un-divided electrochemical cell under constant current mode, with a view to optimize various process parameters, which have a direct bearing on the chlorine dioxide formation efficiency under laboratory conditions. The effect of feed flow rate (10-150 ml min(-1)), feed solution pH (2.3-5.0), concentration of sodium chloride (0-169.4mM), concentration of sodium chlorite (0-7.7 mM), and the applied current (100-1200 mA) on the formation of dissolved ClO(2) gas in solution and the pH of the product-containing solution was investigated by performing single pass experiments, with no circulation, in a cell set-up with Ti/IrO(2) anode and Ti/Pt cathode. The current efficiency and the power consumption were calculated for the optimized conditions.