Estimating postprandial glucose fluxes using hierarchical Bayes modelling

A new stochastic computational method was developed to estimate the endogenous glucose production, the meal-related glucose appearance rate (R(a meal)), and the glucose disposal (R(d)) during the meal tolerance test. A prior probability distribution was adopted which assumes smooth glucose fluxes with individualized smoothness level within the context of a Bayes hierarchical model. The new method was contrasted with the maximum likelihood method using data collected in 18 subjects with type 2 diabetes who ingested a mixed meal containing [U-(13)C]glucose. Primed [6,6-(2)H(2)]glucose was infused in a manner that mimicked the expected endogenous glucose production. The mean endogenous glucose production, R(a meal), and R(d) calculated by the new method and maximum likelihood method were nearly identical. However, the maximum likelihood gave constant, nonphysiological postprandial endogenous glucose production in two subjects whilst the new method gave plausible estimates of endogenous glucose production in all subjects. Additionally, the two methods were compared using a simulated triple-tracer experiment in 12 virtual subjects. The accuracy of the estimates of the endogenous glucose production and R(a meal) profiles was similar [root mean square error (RMSE) 1.0±0.3 vs. 1.4±0.7μmol/kg/min for EGP and 2.6±1.0 vs. 2.9±0.9μmol/kg/min for R(a meal); new method vs. maximum likelihood method; P=NS, paired t-test]. The accuracy of R(d) estimates was significantly increased by the new method (RMSE 5.3±1.9 vs. 4.2±1.3; new method vs. ML method; P<0.01, paired t-test). We conclude that the new method increases plausibility of the endogenous glucose production and improves accuracy of glucose disposal compared to the maximum likelihood method.     

Modeling of the dynamics of transient liquid films in ternary systems

The presence of a concentration gradient across a thin liquid film leads to the phenomenon of isothermal liquid film migration (LFM). In most cases, the concentration gradient is due to coherency stresses, and the migration of the liquid film results in the relaxation of these stresses. It is also possible to envisage cases in which LFM occurs as a result of chemical solubility differences between stable and metastable phases. Both situations are examined in this contribution with special emphasis on the effect of adding a second solute element to the liquid phase. The kinetics of LFM is examined as a function of the initial liquid concentration and the ratio of the solute diffusion coefficients in a model coherency-driven ternary system. The growth of the Γ₂ inside δ particles in the Zn-Fe-Al system is presented as a possible example of chemically driven LFM. This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was held during TMS 2006, the 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University.     

A Multicriteria Decision Support Methodology for Annual Rehabilitation Programs of Water Networks

Abstract:   This article provides an overview of a multicriteria decision support methodology for annual rehabilitation programs of water networks. A first set of criteria is formulated for the purpose of comparing and ranking rehabilitation projects. Each proposed criterion is a measure of a particular impact of the condition of a pipe. The ELECTRE TRI method is implemented for defining rehabilitation priorities . Two reference profiles are used to define the limits of three categories associated with three increasing priority levels. With these two reference profiles, applying the ELECTRE TRI method to an asset stock ( a set of pipes that are candidates for rehabilitation ) means assigning each pipe to one of six possible priority groups. A second set of criteria, based on the concept of efficiency, is proposed for comparing alternative rehabilitation programs ( subsets of the asset stock ).     

AN ENERGY ANALYSIS OF BELT POLISHING PROCESS AND ITS APPLICATIONS TO TIME CYCLE AND TRACKING EFFECTS

Belt polishing is a fine machining process widely used to improve surface texture and to increase wear resistance and fatigue life. Despite the basics of this manufacturing process are not yet well understood, the cycle-time and the belt oscillations frequency are considered as fundamental process variables. In this article, their effects on the surface characterization and on the form aspects are investigated in connection with the principal physical mechanisms activated during the superfinishing operations (cutting, ploughing and sliding). With this aim, an energy approach of the belt polishing process, coupled with SEM observations of the abrasive belt, is introduced. Two belt polishing energetic regimes are identified and then discussed.     

Paclitaxel-Loaded Microparticles for Intratumoral Administration via the TMT Technique: Preparation,Characterization, and Preliminary Antitumoral Evaluation

In our pursuit to develop suitable therapeutic particulate systems for intratumoral delivery by the targeted multi-therapy (TMT) technique, we describe the preparation of paclitaxel-loaded poly(d,l-lactic-co-glycolic) acid (PLGA) microparticles (MPs) (drug loading 35–38%, wt/wt; size 0.7–5 μm). Magnetite (15%, wt/wt) was also incorporated in some preparations for a future magnetic resonance imaging (MRI)-guided delivery. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) experiments showed that paclitaxel was not encapsulated in its initial crystalline form. The paclitaxel in vitro release pattern showed a biphasic tendency with a burst effect followed by a sustained release (28% released amount after 1 month), which was accompanied with MP erosion and degradation signs as confirmed by scanning electronic microscopy (SEM) micrographs. The paclitaxel-loaded MPs demonstrated a dose-dependent antitumor effect on human uterine cancer cells, with an IC₅₀ value relatively close to that of commercial Taxol®. This paclitaxel delivery system represents a potent antiprofilerative and radiosensitizer agent for intratumoral administration via the TMT technique.     

Thermal blooming and photoluminescence characterizations of sol–gel CdO–SiO<Subscript>2</Subscript> with different nanocomposite

The CdO NPs was synthesized using the sol–gel method and the nanoparticles were characterized using an UV–Vis spectrophotometer, with shape and size were examined by SEM and XRD. The XRD analysis respects the Bragg’s law and confirmed the crystalline nature of CdO nanoparticles. From the XRD, the average size of CdO NPs was found to be around 41 nm. The photoluminescence spectra of the CdO NPs, as recorded at room temperature, were excited at 300 nm wavelength. The broad emission peaks were between 600 and 650 nm (orange emission). The optical limiting performance of the nanocomposite was described in the sol–gel state. Also, this study has observed and studied the diffraction rings generated in CdO NPs using the same CW laser. The number of rings increases almost exponentially with an increasing volume fraction of SiO₂ in the nanocomposites. The refractive index change, Δn, and effective nonlinear refractive index, n ₂, were found to be 10^?4 and 10^?8 cm²/W, respectively. The effective nonlinear refractive index, n ₂, was determined based on the observed number of rings. The threshold values of the CdO, CdO–2SiO₂ and CdO–5SiO₂ nanocomposites are 7.1, 6.55 and 6.34 mW, respectively. This large nonlinearity is attributed to the thermal effect. The present studies suggest that the nanocomposite is a potential candidate for optical device applications such as the optical limiters. The thermal blooming technique was applied to evaluate the thermo-optic coefficient and thermal diffusivity of the CdO NPs. In the thermal blooming experimental setup a transistor–transistor logic modulated CW laser of wavelength 532 nm was used as the excitation source.     

Electrochemical Behavior of Single CuO Nanoparticles: Implications for the Assessment of their Environmental Fate

The electrochemical behavior of copper oxide nanoparticles is investigated at both the single particle and at the ensemble level in neutral aqueous solutions through the electrode‐particle collision method and cyclic voltammetry, respectively. The influence of Cl^? and NO₃^? anions on the electrochemical processes occurring at the nanoparticles is further evaluated. The electroactivity of CuO nanoparticles is found to differ between the two types of experiments. At the single‐particle scale, the reduction of the CuO nanoparticles proceeds to a higher extent in the presence of chloride ion than of nitrate ion containing solutions. However, at the multiparticle scale the CuO reduction proceeds to the same extent regardless of the type of anions present in solution. The implications for assessing realistically the environmental fate and therefore the toxicity of metal‐based nanoparticles in general, and copper‐based nanoparticles in particular, are discussed.     

Effect of oxygen partial pressure on the microstructural and physical properties on nanocrystalline tin oxide films grown by plasma oxidation after thermal deposition from pure Sn targets

In this work, microstructural and physical properties were studied in the tin oxide films deposited by thermal evaporation of Sn films on stainless steel substrates followed by in situ D.C. plasma oxidation at 200 °C substrate temperature. The surface properties were studied by scanning electron microscopy, X-ray diffraction, atomic force microscopy and four-point probe electrical resistivity. The typical calculated grain size of the films deposited by thermal evaporation was between 28 nm and 66 nm and the texture structure was found to be dependent on the thermal deposition pressure. A cassiterite structure of SnO₂ was produced by D.C. plasma oxidation with the main diffraction peaks of the (101), (200), (211), (310) and (221) planes at the 25% and 50% O₂ partial pressure conditions. However, at 12.5% O₂ partial pressure oxidation conditions, amorphous tin oxide structure and crystalline SnO phases were detected. Increasing thermal deposition pressure resulted in preferential texture formation at (211) and (310) planes. The surface structure investigation of the produced films by SEM and AFM studies showed large SnO₂ islands with approximately 1.0 μm and 1.5 μm sized nodules, and they are called as grape-like structures. The grape-like grains possess nano grains, which are between 20 nm and 30 nm in diameter calculated by Scherer's formula. The grape-like grains were seen to be separated by large cavities and the size of these cavities and nano grains was seen to be larger when the O₂ partial pressure is increased. The four-point probe resistivity of the films, grown at different oxidation temperatures, decreased with the increase in oxygen partial pressure. The values of resistivity for SnO₂ phase were measured as low as 10⁻⁵ Ω-cm and observed to decrease with increasing thermal deposition pressure and oxygen partial pressure.