A kinetic study on anaerobic reduction of sulphate, part II: incorporation of temperature effects in the kinetic model

The effects of temperature on the kinetics of anaerobic sulphate reduction were studied in continuous bioreactors using acetate as an electron donor. Across the range of temperatures applied from 20 to , the increasing of volumetric loading rate up to 0.08 to resulted in a linear increase in reduction rate of sulphate. The increasing reaction rate showed a lower dependence on volumetric loading rate in the range 0.1-. Further increase in volumetric loading rate above was accompanied by wash out of bacterial cells and a sharp decrease in reaction rate. Despite a similar pattern for dependency of reaction rate on volumetric loading at all temperatures tested, the magnitude of reaction rate was influenced by temperature, with a maximum rate of observed at . The effect of temperature on maximum specific growth rate (μ_max) and bacterial yield was insignificant. The values of maximum specific growth rate and yield were and 0.56-0.60 kg bacteria (), respectively. The decay coefficient (k_d) and apparent saturation constant () were both temperature dependent. The increase of temperature resulted in decreased values of , and higher values for k_d. Using the experimental data effect of temperature was incorporated in a kinetic model previously developed for anaerobic reduction of sulphate.     

Antioxidant Activity,Reaction Mechanisms,and Kinetics of Matricaria recutita Extract in Commercial Blended Oil Oxidation

Antioxidant activity, reaction mechanisms, and kinetics of Matricaria recutita crude extract (CE; total phenolics: 41 ± 2.5 mg/g, total flavonoids: 26 ± 1.4 mg/g, IC₅₀: 82.3 ± 2.8 µg/mL and reducing power: 10.45 ± 0.56 mmol Fe²⁺/mass) in comparison to tert-Butylhydroquinone during oxidation of blended vegetable oil (sunflower, soybean, and palm oil) at 120, 130, and 140°C were studied. Good correlations existed between the Rancimat oil stability index and stability indices (induction period) calculated from peroxide value, conjugated diene value, and anisidine value with no significant differences in kinetic parameters calculated from them. The temperature acceleration (Q₁₀), activation energy (E_a), frequency factor (A), enthalpy (ΔH⁺⁺), entropy (ΔS⁺⁺), and free energy of activation (ΔG⁺⁺) for oils containing crude extract were lower than for oils containing tert-Butylhydroquinone (0.0025, 0.005, 0.01, and 0.02%). Values were independent of crude extract or tert-Butylhydroquinone concentration. For crude extract and tert-Butylhydroquinone, E_a and A were well correlated with ΔH⁺⁺ and ΔS⁺⁺ values, respectively, but correlation between E_a and Q₁₀ for crude extract compared to tert-Butylhydroquinone was poor. Furthermore, the rate of Monounsaturated:Polyunsaturated fatty acids formation did not differ significantly between crude extract and tert-Butylhydroquinone, but concentrations of them did affect Monounsaturated:Polyunsaturated ratio. Based on the results obtained, crude extract decreased the rate of the oxidation reaction due to the decrease in the concentration of the activated complex and reduction in the rate at which the activated complex dissociated into oxidation products.     

Synthesis of fluorescent ABA triblock copolymer via click reaction

A hyperbranched–linear–hyperbranched (ABA) triblock copolymer containing poly(ethylene glycol) (PEG) as linear block and polyglycerol (hbPG) as hyperbranched blocks has been synthesized through a copper‐catalysed click reaction. In order to synthesize the hyperbranched block, propargyl alcohol‐initiated ring‐opening multibranching polymerization of glycidol was used to prepare hbPG with the propargyl segment in the focal point (CH?C? hbPG). Separately, PEG was functionalized at both ends using cyanuric chloride, and then the chloride groups of cyanuric chloride were substituted by azide groups. Finally, the azide‐functionalized PEG was conjugated to CH?C? hbPG via a click reaction. Substitution of the chlorine atoms of cyanuric chloride under different conditions together with click chemistry allows the synthesis of a variety of polymeric architectures. In the last step, fluorescein was attached to the block copolymer as a fluorescent probe in order to study the cell internalization of this copolymer. This type of triblock copolymer is a promising future nanomaterial for simultaneous drug delivery and cell imaging. © 2016 Society of Chemical Industry     

Preparation of hydroxyapatite-calcium ferrite composite for application in loading and sustainable release of amoxicillin: Optimization and modeling of the process by response surface methodology and artificial neural network

In this research, a merit carrier consisting of hydroxyapatite and calcium ferrite (HAp-CaFe₂O₄) was prepared via a convenient procedure and characterized using a series of techniques, including XRD, FE-SEM, TEM, EDS mapping, BET/BJH, VSM, and TGA. The loading of Amoxicillin (AMX) onto HAp-CaFe₂O₄ was optimized and modeled by two powerful approaches, namely response surface methodology (RSM) and artificial neural network (ANN). RSM-optimized results demonstrated that the maximum drug loading efficiency was 91.76% at a carrier dosage of 1.2 g, a drug concentration of 30 mg L^?1, and a pH of 6.5 within a stipulated time of 60 min. ANN modeling revealed that the pH of the solution had a dramatic effect with a 35% impact on the drug loading process. The downloading of AMX by HAp-CaFe₂O₄ was consistent with pseudo-2nd order and intra-particle diffusion kinetics models as well as the Temkin isotherm model, implying the chemisorption of the drug molecules on the carrier. The AMX release was evaluated at different pHs, and it was revealed that the sustained and prolonged drug evacuation occurred in the neutral medium as compared to acidic and basic media. The conformity of the drug release kinetics to the Korsmeyer-Peppas model indicated that the Fickian diffusion dominated the AMX release. The MTT assay showed the biocompatibility and safety of HAp-CaFe₂O₄ toward A549 cell lines.In summary, as-prepared HAp-CaFe₂O₄ can be regarded as a biocompatible and stimuli-responsive carrier for controlled and targeted drug delivery systems.     

A note on evaluating the risk in continuous review inventory systems

This paper is an attempt to evaluate the long term risk of stock-out and obsolescence in continuous review inventory systems, typically of slow-moving but very critical items. Inventory decisions depend very much on the goodness of the estimates of the input parameters like the holding, ordering and stock-out costs. It is a well-known fact that stock-out cost is a very difficult parameter to estimate. The lower it is the lower the quality of service will be while the higher it is the higher the inventory cost would be and possibly higher obsolescence rate too. In this paper, we develop a framework to evaluate the risks, in the long term, of stock-out and obsolescence, especially for inventory of critical spares whose demand rate is not high. For this purpose, we propose the use of quasi-stationary distributions for continuous review (r, Q) inventory systems with the condition that the Laplace transforms of functions of interest are rational algebraic functions. We relate the quasi-stationary distribution to the conditional tail expectation which is a coherent risk measure used in finance and actuarial studies. Numerical illustration is also provided.     

Scheduling Part‐Families Under FMS: To Mix or Not to Mix?

This paper considers the issue of whether to mix part-types in one or several of the families to be produced in a flexible manufacturing system (FMS). For this input control problem in an FMS, we have derived conditions that support the mixing of a part-type, which can share the setup of other part-types, in deterministic environment. The problem is identified as a special economic lot scheduling problem (ELSP), and is formulated as a linear programming problem. Analytical insights are derived by considering the special case with three part-families. The results are illustrated with a numerical example.     

Organic photovoltaic cells based on self-assembly fabrication of vertically aligned CuPc nanorods upon fullerene particles

We demonstrate the self-assembled growth of vertically aligned Copper Phthalocyanine (CuPc) nanorods which are directly evaporated on fullerene (C₆₀) islands. UV–Vis spectroscopy of CuPc nanorods, compared to planar CuPc, shows an improvement in light absorption within the visible range. Moreover, scanning electron microscopy (SEM) demonstrates the presence of well-arranged vertically aligned CuPc nanorods suggesting an increase in the donor–acceptor interface. X-ray diffraction (XRD) reveals the crystalline nature of these nanorods. Different organic photovoltaic cells have been fabricated using these nanorods. High current density achieved with the cell arrangement of CuPc/CuPc-nanorods/C₆₀ in comparison to regular planar CuPc/C₆₀ device. The power conversion efficiency is also doubled compared to the planar one.     

BTI characteristics and mechanisms of metal gated HfO/sub 2/ films with enhanced interface/bulk process treatments

Significant deviations in BTI characteristics for metal gate HfO/sub 2/ films compared to silicon oxide based films prove that conventional reliability models based on SiO/sub 2/ films can no longer be directly applied to HfO/sub 2/ based MOSFETS. This study shows the use of conventional accelerated reliability testing in the Fowler-Nordheim tunneling regime to extrapolate time to failure at operating voltages (direct tunneling regime) overestimates device lifetimes. Additionally, unlike conventional gate oxides, the slope of /spl Delta/V/sub t/ versus time (or the rate of charge trapping) in HfO/sub 2/ MOSFETS is dependent on stress voltage. The HfO/sub 2/ based metal gated nMOSFETS show poor PBTI characteristics and do not meet the 10 year lifetime criterion for threshold voltage stability. On the other hand, HfO/sub 2/ based pMOSFETS show superior NBTI behavior and meet the 10 year lifetime criterion. These results are contrary to the observations with conventional gate dielectrics. This paper explores the anomalous charge trapping behavior and provides a comprehensive study of the PBTI characteristics and recovery mechanisms in metal gated HfO/sub 2/ films.     

Integral sliding mode control for nonlinear damped model of arch microbeams

Microsystem Technologies - In this paper, a second order integral sliding mode controller (SMC) and a two-dimensional integral sliding mode controller are designed for a nonlinear damped model of...