Quantitative analysis of the factors responsible for over or under dose of 131 I therapy patients of hyperthyroidism

Radioiodine (131 I) therapy has been in use for more than 60 y. Several protocols have been suggested and used for prescribing the activity to be administered to the patients for the treatment of hyperthyroidism; application of these protocols may result in an under or over dose of the hyperthyroid patients. The main objective of this study was to carry out quantitative analysis of the factors responsible for possible under or over dosage of the patients. In this regard, a total of 59 patients [15 diffuse goitre (DG) and 44 nodular goitre (NG) cases] were studied. In order to compare the thyroid doses calculated by using different protocols, the dosimetric approach was followed. 131 I uptakes were measured after 24 and 48 h, respectively, by giving 0.5 MBq of 131 I to each patient. Thyroid mass and effective half-life were also calculated for each patient and the variations in the thyroid doses were analysed. According to the results 28 and 54% patients were under dosed and 72 and 46% patients were over dosed with DG and NG, respectively. The protocols, which have not taken into account the thyroid mass, multi pre-therapeutic 131 I uptakes and the effective half-life of 131 I of the individual patient, showed a higher degree of deviation from the required thyroid dose. Besides these parameters, some fundamental factors such as radiosensitivity, previous exposure to thyroid drugs and duration of the disease are recommended to be incorporated, which can certainly affect the clinical out comes.     

Simultaneous preconcentration and determination of U(VI), Th(IV), Zr(IV) and Hf(IV) ions in aqueous samples using micelle-mediated extraction coupled to inductively coupled plasma-optical emission spectrometry

A simple cloud point extraction method followed by inductively coupled plasma-optical emission spectrometry (ICP-OES) was developed for simultaneous preconcentration and determination of trace amounts of U(VI), Th(IV), Zr(IV) and Hf(IV) ions in aqueous samples. The metal ions in 50 ml of aqueous solution (containing 0.1 M sodium acetate, pH 6.0) were formed complexes with dibenzoylmethane (DBM). Then, Triton X-114 (0.2%, w/v) was added to the solution. By increasing the temperature of the solution up to 50 degrees C, a phase separation occurred. After centrifugation at 4000 rpm for 6 min, the surfactant-rich phase (sediment phase) was diluted with 1.0 ml of 20:80 (v/v) of methanol/1 M HNO(3). The metal ions were then determined using ICP-OES. Finally, the main factors affecting the cloud point extraction were evaluated and optimized. Under optimized conditions, enhancement factors in the range of 37.0-43.6 were obtained. The calibration graphs were linear in the range of 0.5-1500 microg l(-1) for Th and Zr, 0.5-500 microg l(-1) for Hf and 2.5-1240 microg l(-1) for U with correlation coefficients (r(2)) better than 0.9926. The detection limits were between 0.1 and 1.0 microg l(-1) and the R.S.D. values for seven replicates were lower than 6.1%.     

Influence of electric discharge machining on fatigue limit of high strength aluminum alloy under finish machining

Abstract

The aim of this study was to investigate the fatigue limit of the electric discharge machined aluminum alloy 2024 T6. Machining was performed at 3, 6, 9, and 12 A discharge current values while all other parameters were kept constant. The fatigue tests were performed on a four-point rotating bending machine at the frequency of 50 Hz and at ambient temperature. Fatigue limits at 10⁷ cycles were determined using staircase (up-and-down) method and the obtained data was analyzed statistically. For reference purposes, fatigue strength of the conventionally turned specimens was also found by the same technique. The EDM surface is characterized by its morphology, roughness, hardness, and thickness of the resolidified layer. The effects of discharge current values on these surface characterizing parameters and subsequent influence on fatigue limit have been discussed.     

Developing the Processing Maps Using the Hyperbolic Sine Constitutive Equation

Hot compression tests were performed on a duplex stainless steel at temperatures ranging from 1223 K to 1473 K (950 °C to 1200 °C) and strain rates from 0.001 to 100 s^?1. The constitutive analysis of flow stress was carried out using the hyperbolic sine function, and the material constants were determined at two typical strains of 0.3 and 0.7. The power dissipation map, instability map, and processing map for the material were developed for strains of 0.3 and 0.7. The developed processing maps were based on the hyperbolic sine as well as the conventional power-law constitutive equations. The efficiency of power dissipation (η) varied from 12 to 60 pct over the studied temperature and strain rate. The highest value of η was obtained at strain rates below 0.01 s^?1, whereas the lowest value of η was observed at the intermediate strain rates. The instability region in sin h-based processing map was only observed in the range of 1423 K to 1473 K (1150 °C to 1200 °C) and at a strain rate of 100 s^?1, while the conventional processing map did not predict any instability region. Optical microscopy observations were more consistent with the results of the sin h-based processing map and indicated that the instability regime at high temperatures and high strain rates was due to the development of adiabatic shear bands.     

Polyamide 6 nanocomposites incorporating cellulose nanocrystals prepared by In situ ring‐opening polymerization: Viscoelasticity,creep behavior,and melt rheological properties

The creep behavior and solid and melt linear viscoelasticity of novel polyamide 6 (PA6) nanocomposites reinforced with cellulose nanocrystals (CNCs) prepared via in situ anionic ring‐opening polymerization (ROP) were investigated to accelerate research efforts to develop new polymeric materials with improved properties for lightweight, load‐bearing applications. The obtained results showed that incorporation of relatively small amounts of ≤ 2wt% CNCs into the PA6 thermoplastic matrix gave nanocomposite samples with significantly enhanced creep and viscoelastic materials functions of the PA6 as indicated by lower creep strain, lower creep compliance, improved elastic recovery after removal of load, and reduced Arrhenius activation energies for time‐dependent viscoplastic flow. The obtained results were analyzed and interpreted by theoretical equations for predicting the viscoelasticity and creep behavior of polymeric systems. The melt rheological properties showed enhanced melt strength and elasticity. The formation of a percolated network structure of CNC was revealed by morphological observations that were consistent with the dynamic structure break‐up and reformation rheological experiments. The stiffness, rigidity of the CNCs along with their special ROP‐facilitated intrinsic strong chemical interactions with the PA6 matrix is believed to be responsible for the observed superior creep and viscoelastic materials functions even with very little CNC concentration. POLYM. ENG. SCI. 56:1045–1060, 2016. © 2016 Society of Plastics Engineers     

HANDY: a hybrid association rules mining approach for network layer discovery of services for mobile ad hoc network

Mobile ad hoc network (MANET) is an infrastructure-less network formed between a set of mobile nodes. The discovery of services in MANET is a challenging job due to the unique properties of network. In this paper, a novel service discovery framework called hybrid association rules based network layer discovery of services for ad hoc networks (HANDY) has been proposed. HANDY provides three major research contributions. At first, it adopts a cross-layer optimized design for discovery of services that is based on simultaneous discovery of services and corresponding routes. Secondly, it provides a multi-level ontology-based approach to describe the services. This resolves the issue of semantic interoperability among the service consumers in a scalable fashion. Finally, to further optimize the performance of the discovery process, HANDY recommends exploiting the inherent associations present among the services. These associations are used in two ways. First, periodic service advertisements are performed based on these associations. In addition, when a response of a service discovery request is generated, correlated services are also attached with the response. The proposed service discovery scheme has been implemented in JIST/SWANS simulator. The results demonstrate that the proposed modifications give rise to improvement in hit ratio of the service consumers and latency of discovery process.     

Single fiber colorless symmetric WDM-PON architecture using time interleaved remodulation technique for mitigating Rayleigh backscattering resilience

A time interleaved differential phase shift keying (DPSK) remodulation technique is proposed to mitigate the effect of Rayleigh backscattering (RBS)-induced noise in a single fiber colorless wavelength-division-multiplexing passive optical network (WDM-PON). In order to achieve a cost effective optical network unit (ONU) solution without dedicated laser sources for upstream signals to provide optimum symmetric capacity in a colorless WDM-PON, remodulation becomes the core attraction. Also as the performance of colorless WDM-PON systems suffers from the transmission impairments due to RBS, it is mitigated by using this remodulation scheme. Simulation results show that downstream and upstream signals achieve the error-free performance at 10 Gbit/s with negligible penalty, and enhance the tolerance to RBS-induced noise over a 25 km single-mode fiber.     

Experimental investigation on CO2-light crude oil interfacial and swelling behavior

A systematic series of experiments are designed and performed including interfacial tension(IFT) measurements concomitant with Bond(BN,the ratio of gravity forces to capillary forces) and swelling/extraction measurements.Dynamic IFT, BN and swelling/extraction are measured as a function of pressure at temperatures of 30,50 and 80 ℃.In addition, in the light of measured IFT the minimum miscibility pressure(MMP) of CO_2 and light crude oil is determined based on a method called vanishing interfacial tension(VIT). The obtained results interestingly revealed that equilibrium IFT decreases linearly with pressure in two distinct pressure intervals while equilibrium BN shows an increasing trend as a function of pressure for all of the studied cases while no obvious trend is observed for swelling of crude oil and extraction of light-components regarding time, temperature and pressure.     

The impact of connate water saturation and salinity on oil recovery and CO2 storage capacity during carbonated water injection in carbonate rock

Carbonated water injection (CWI) is known as an efficient technique for both CO₂ storage and enhanced oil recovery (EOR). During CWI process, CO₂ moves from the water phase into the oil phase and results in oil swelling. This mechanism is considered as a reason for EOR. Viscous fingering leading to early breakthrough and leaving a large proportion of reservoir un-swept is known as an unfavorable phenomenon during flooding trials. Generally, instability at the interface due to disturbances in porous medium promotes viscous fingering phenomenon. Connate water makes viscous fingers longer and more irregular consisting of large number of tributaries leading to the ultimate oil recovery reduction. Therefore, higher in-situ water content can worsen this condition. Besides, this water can play as a barrier between oil and gas phases and adversely affect the gas diffusion, which results in EOR reduction. On the other hand, from gas storage point of view, it should be noted that CO₂ solubility is not the same in the water and oil phases. In this study for a specified water salinity, the effects of different connate water saturations (S_wc) on the ultimate oil recovery and CO₂ storage capacity during secondary CWI are being presented using carbonate rock samples from one of Iranian carbonate oil reservoir. The results showed higher oil recovery and CO₂ storage in the case of lower connate water saturation, as 14% reduction of S_wc resulted in 20% and 16% higher oil recovery and CO₂ storage capacity, respectively.     

Forest biomass supply logistics for a power plant using the discrete-event simulation approach

This study investigates the logistics of supplying forest biomass to a potential power plant. Due to the complexities in such a supply logistics system, a simulation model based on the framework of Integrated Biomass Supply Analysis and Logistics (IBSAL) is developed in this study to evaluate the cost of delivered forest biomass, the equilibrium moisture content, and carbon emissions from the logistics operations. The model is applied to a proposed case of 300 MW power plant in Quesnel, BC, Canada. The results show that the biomass demand of the power plant would not be met every year. The weighted average cost of delivered biomass to the gate of the power plant is about C$ 90 per dry tonne. Estimates of equilibrium moisture content of delivered biomass and CO₂ emissions resulted from the processes are also provided.