The importance of axial misalignment on the long term strength of polyethylene pipe butt fusion joints

The importance of axial misalignment at polyethylene pipe butt fusion joints has been assessed by undertaking elevated temperature lifetime tests. Both medium and high density polyethylene pipes were fusion joined to give aligned and controlled misaligned butt joints. These were tested under either a constant or fluctuating internal pressure loading using conditions that induced failure by slow, stable crck growth. It was observed that the lifetime of a butt joined system depends upon both the internal pressure or pressure range applied and the level of misalignment at the butt fusion joint. Increasing either the internal pressure (range) or the misalignment reduced system performance. These two variables of misalignment and internal pressure (range) may be incorporated into a single parameter, the amplified axial stress (or stress range) at the butt joint. This amplified or butt joint axial stress (or stress range) may be derived by considering the additional bending stresses introduced at the butt joint by virtue of misalignment combined with the axial stress loading.     

Influence of heat-stable filler on the thermal shielding performance of water-based intumescent fire-resistive coating for structural steel applications

Intumescent coatings are the newest passive fireproofing materials which maintain structural integrity of high-rise buildings in fire events. The present work focuses on the influence of zirconium silicate as a heat-stable filler in intumescent coatings. Different coatings were formulated by varying the zirconium silicate concentration from 1, 3, 5, 8, and 10 on parts per hundred basis (phr). Fire performance of the coatings was then determined by fire test using a Bunsen burner fire flame at 950°C for 1 h. The degradation of coatings was examined by thermogravimetric analysis (TGA). The morphology of the intumescent chars was analyzed by environmental scanning electron microscopy. The char was also examined by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy. XRD confirmed the inertness of zirconium silicate with intumescent ingredients at high temperatures. TGA showed an increase in the weight residue of char at high temperature. The incorporation of zirconium silicate into intumescent coating forms a thermally stable char with better substrate adhesion. EDS analysis confirmed an increase in the antioxidation property of the char, and the fire test also confirmed an increase in char strength of coatings by the incorporation of zirconium silicate.     

Determining the Tensile Stress-Crack Opening Curve of Concrete by Inverse Analysis

The determination of the fundamental stress versus crack opening (σ-w) response of concrete under uniaxial tension is performed in this study through inverse analysis using data from notched beam tests. The procedure used for optimizing the parameters of the σ-w relation using the load versus crack mouth opening displacement response of the notched beam is described. Satisfactory comparisons have been obtained between the σ-w curves obtained through the inverse analysis and those directly measured in uniaxial tension tests. The use of weighting functions in the inverse analysis may be necessary when large crack widths are to be considered.     

The steady-state kinetics of parallel reaction networks

The conventional kinetic analysis of an overall reaction (OR) is limited to a single sequential pathway of molecular steps at a time, based either on the general quasi-steady state (QSS) approach of Bodenstein, or on the much simpler but limited Langmuir–Hinshelwood–Hougen–Watson (LHHW) approach based on assuming a single rate-determining step (RDS), the remaining being quasi-equilibrated (QE). We recently described a new algebraic methodology for deriving the QSS rate expression for a reaction sequence, which allowed interpretation of the final result in an Ohm's law form, i.e., OR rate=OR motive force/OR resistance of an equivalent electric circuit, where the consecutive mechanistic steps represent resistors in series. Here, we propose a similar Ohm's law form of QSS rate for a reaction system involving parallel pathways, whose equivalent electrical circuit derives directly from the reaction route (RR) Graph of its mechanism, as proposed earlier by us. The results are exact for a reaction network with mechanistic steps linear in intermediates concentrations, while they are approximate, albeit accurate, for non-linear step kinetics. We further show how the LHHW methodology, combined with the concept of intermediate reaction might be utilized to obtain the step resistances involved. For illustration, we utilize the relatively simple examples of: (1) the gas-phase hydrogen–bromine non-catalytic reaction (non-linear kinetics), and (2) zeolite catalyzed N₂O decomposition reaction (linear kinetics). However, the approach is useful for more complex non-catalytic, catalytic and enzymatic reactions networks as well.     

N,N‐dichloro poly(styrene‐co‐divinyl benzene) sulfonamide polymeric beads: An efficient and recyclable decontaminating reagent for O,S‐diethyl methyl phosphonothiolate,a simulant of VX

An efficient and operationally simple method is developed for chemical decontamination of simulant of VX. A new chlorine bearing reagent N,N‐dichloro poly(styrene‐co‐divinyl benzene) sulfonamide was developed to deactivate the simulant of VX in aqueous medium. This decontamination reaction was monitored by gas chromatography (GC), and the products were analyzed by gas chromatography‐mass spectrometry (GC‐MS). This reagent has advantage over earlier reported reagents in terms of effectiveness, stability, nontoxicity, cost, ease of synthesis, recyclablity (collected after filtration, rechlorinated, and used for further reaction), and decontamination of simulant of VX to give single nontoxic product at room temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Kinetics of emitted mass—A study with three dry powder inhaler devices

The purpose of this study was to understand the kinetics of emptying of micronised salbutamol sulphate (SS) and lactohale 300 (LH300) under varying air flow rates (30–180 L min⁻¹) from three dry powder inhaler devices, Rotahaler^® (RH), Monodose Inhaler^® (MI) and Handihaler^® (HH). Aerosol concentration vs. time profiles, determined through real-time laser diffraction particle sizing, demonstrated that the majority of the powder from RH was emitted within one second while a more prolonged aerosolisation was observed from MI and HH. Peak aerosol concentrations were achieved more rapidly from RH compared to MI for both SS and LH300. Calculated cumulative emitted mass (CCEM) vs. time profiles were obtained from the aerosol concentration vs. time profiles and the emitted mass and the rate of CCEM (k_CCEM), estimated from a modelling approach, increased with increasing air flow rates. The k_CCEMvs. air flow rate profiles of SS and LH300 were significantly different at high air flow rates. The k_CCEM was highest from RH and lowest from MI. Differences in k_CCEM between the devices were related to capsule aperture size while the differences between the materials were due to the powder bed structure. This approach provided an understanding of the rate at which powder mass emptied from dry powder inhaler devices and was proposed to be a powerful development tool for the future powder inhalers.     

Indole‐based polymer and its silver nanocomposite as advanced antibacterial agents: synthetic path,kinetics of polymerization and applications

Atom transfer radical polymerization of 1‐allylindole‐3‐carbaldehyde (AIC) was studied by employing 2‐bromoisobutyryl bromide as initiator in toluene. It led to controlled radical polymerization of AIC, with an increase of molecular weight along with the conversion of the monomer, and a relatively narrow molar mass distribution was obtained, as determined by gel permeation chromatography. The living nature of poly(1‐allylindole‐3‐carbaldehyde) (PAIC) was confirmed by the chain extension polymerization whereas ¹H NMR analysis showed that the major population of PAIC retained the chain‐end functional group. PAIC and its silver nanocomposite were found to be biologically active against some tested bacterial pathogens. Minimum inhibitory concentration tests revealed that PAIC exhibited antibacterial activity against Staphylococcus aureus, Proteus mirabilis and Klebsiella pneumonae whereas PAIC/Ag nanocomposite showed antibacterial activity against Enterococcus faecalis and K. pneumonae. © 2012 Society of Chemical Industry     

A Pyropheophorbide Analogue Containing a Fused Methoxy Cyclohexenone Ring System Shows Promising Cancer-Imaging Ability

Herein we report the synthesis, photophysical properties, positron emission tomography (PET) imaging and photodynamic therapy (PDT) efficacy of methyl 3-(1′-m-iodobenzyloxy)ethyl-3-devinyl-verdin 4 (with or without the ¹²⁴I isotope). The PET imaging ability and ex vivo biodistribution of [¹²⁴I] 4 were compared with the well-studied methyl [3-(¹²⁴1′-m-iodobenzyloxy)ethyl]-3-devinyl-pyropheophorbide-a methyl ester (PET-ONCO or [¹²⁴I] 2 ) and [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG) in BALB/c mice bearing colon-26 tumors. Whole-body PET images of [¹²⁴I] 4 containing a fused methoxy cyclohexenone ring system showed excellent tumor contrast with time (72>48>24 h post-injection). Ex vivo biodistribution results indicate that relative to the current clinical standard [¹⁸F]FDG and [¹²⁴I] 2 in 2 % ethanol formulation, [¹²⁴I] 4 , at the same radioactive dose (25 μCi per mouse), showed higher tumor uptake at 24 h post-injection and longer tumor retention. In biological environments, compound 4 showed lower fluorescence and lower singlet oxygen yield than 2 , which is possibly due to higher aggregation caused by the presence of a fused cyclohexenone ring system, resulting in limited in vitro/in vivo PDT efficacy. Therefore, the chlorophyll-a analogue [¹²⁴I] 4 provides easy access to a novel PET imaging agent (with no skin phototoxicity) to image cancer types—brain, renal carcinomas, pancreas—in which [¹⁸F]FDG shows limitations.     

Optical and electrical characterization of conducting polymer-single walled carbon nanotube composite films

The optical and electrical properties of the conducting polymer poly(3-hexylthiophene) and single walled carbon nanotube (SWCNT) composites have been investigated. The composites were prepared by dispersing carbon nanotubes in the polymer matrix already dissolved in 1,2-dichlorobenzene. The optical absorption, photoluminescence (PL) and electrical conductivity of the composite was studied as a function of SWCNT concentration in the solution. The absorption coefficient of the polymer was found to be unaffected upto a SWCNT concentration 5% w/w. However a minor decrease in the absorption in visible region was observed for higher SWCNT concentrations. The intensity of PL emission from the composite was measured and was found to decrease with the increase in SWCNT concentration. For a SWCNT concentration of 30% w/w, ∼90% of the PL was quenched, indicating an ultra fast transfer of photoinduced charges from donor polymer to acceptor SWCNT. Direct current conductivity of the composite film was found to increase rapidly with the increase in SWCNT concentration and an increase of ∼5 orders of magnitude was observed for a 30% w/w concentration. The enhancement in conductivity is explained in terms of percolation theory with an estimated percolation threshold of 2% w/w.