Covalent immobilization of antibodies for the preparation of immunoaffinity chromatographic supports

Immunosorbents in immunoaffinity chromatography (IAC) are prepared by immobilizing expensive antibodies without guidelines for ensuring the best coupling efficiencies, and avoiding low binding capacities. Covalent immobilization of antibodies on N-hydroxysuccinimide (NHS)-activated Sepharose 4 Fast Flow resin was optimized using human IgG via full factorial design with incubation times (4, 9, 14, 19 and 24 h), temperatures (4°C and 20°C) and coupling reaction buffers (sodium bicarbonate and triethanolamine). The best coupling efficiency (CE) (83.4 ± 8.7%) was reached with triethanolamine buffer, 14 h and 4°C. Comparison of antibody isotypes (IgG or IgM) by a nested factorial analysis suggested that antibodies in the IgG isotype presents the best coupling efficiency.     

Kinetic Modeling of Inhibition of Ammonia Oxidation by Nitrite under Low Dissolved Oxygen Conditions

In recent years the application of partial nitrification techniques has been denoted as very promising. These methods are based on the oxidation of ammonia to nitrite and the inhibition of the nitratation using different strategies. In most cases, this inhibition causes an increase in the concentration of nitrite. However, the effect of high nitrite concentrations under low dissolved oxygen (DO) conditions on the nitrification process is not well understood. In this paper, the effect of ammonia, nitrite, and nitrate concentrations on the nitrification process under low dissolved oxygen concentrations were studied using respirometric techniques. Results showed that the specific oxygen uptake rate (SOUR) followed a Monod-type equation with respect to the DO concentration. The coefficient SOURm was constant with respect to the ammonia, nitrite, and nitrate within the tested concentrations; in addition, KO was constant with respect to ammonia and nitrate but it increased linearly with the nitrite concentration, suggesting that nitrite was a competitive inhibitor of the SOUR. The inhibitory effect of nitrite was reverted by washing, in accordance with a competition model. From the data obtained using the open respirometer, the ratio between the oxygen consumption (OC) corresponding to each pulse of ammonia at different nitrite concentrations and the OC in the absence of nitrite (OCO) was calculated. The experimental ratio OC/OCO was almost constant with respect to the nitrite concentration and it was close to the literature value. Finally, simulation results agree with the experimental data confirming that the proposed competition model represented adequately the inhibitory effect of nitrite on the respiration rate of ammonia-oxidizing bacteria.     

Optimal controllability of wind generators in a delegated dispatch

A delegated dispatch is a control centre that transmits the requirements of the system operator in critical situations to distributed generation resources, by monitoring and controlling the wind generation producers in a region. When the system needs corrective actions, the system operator sends these requirements to the delegated dispatches. Each delegated dispatch is responsible for matching the goals specified by the system operator, specifying commands and settings to the involved wind generators. In the present paper, some functions of a delegated dispatch are analysed, when applied to a real network. An optimization method is proposed, aiming to reach the regional constraints imposed by the system operator. In the formulation, variations in the output restriction for wind provision, different wind turbines technologies and active and reactive controllability actions are considered.     

TinySOA: a service-oriented architecture for wireless sensor networks

Wireless sensor networks provide the means for gathering vast amounts of data from physical phenomena, and as such they are being used for applications such as precision agriculture, habitat monitoring, and others. However, there is a need to provide higher level abstractions for the development of applications, since accessing the data from wireless sensor networks currently implies dealing with very low-level constructs. We propose TinySOA, a service- oriented architecture that allows programmers to access wireless sensor networks from their applications by using a simple service-oriented API via the language of their choice. We show an implementation of TinySOA and the results of an experiment where programmers developed an application that exemplifies how easy Internet applications can integrate sensor networks.

Thermal kinetic degradation of anthocyanins in a roselle (Hibiscus sabdariffa L. cv. 'Criollo') infusion

The degradation kinetics of anthocyanins in a Roselle infusion (Hibiscus sabdariffa L.), as assessed by visible absorption spectroscopy (absorbance at 520 nm), was verified (60–100 °C). The rate constants for absorbance retention were obtained from first-order reaction kinetic plots. Based on an Arrhenius-type model, the experimental data showed an energy of activation of 15.83 kcal mol⁻¹ (66.22 kJ mol⁻¹) and a Q₁₀ value of 1.01. The obtained pattern allows to predict the retention of these antioxidant compounds as a function of temperature and time of thermal treatment.     

Model to simulate high temperature oxidation kinetics of zircaloy-4: Parabolic and linear behaviour

A calculation code to simulate parabolic and linear behaviour of Zircaloy-4 oxidation between 600 and 862°C in water vapour was developed. This code consists of solving the diffusion equations by the finite-difference method. This method in its explicit version was employed previously, but this type of calculation becomes impracticable with present-day computers when attempts are made to simulate long-term experiments (24 h). This is why the implicit finite-difference method is proposed here: this method has the advantage of drastically reducing the calculation time. The code allowed us to calculate the relationship between the oxygen mass in theα-phase to the total oxygen mass, the oxide thickness and the diffusion profile of oxygen in the α-phase.The results obtained with the model are compared with experimental data existing in the literature for Zircaloy-4, although it could be applied to pure zirconium or other zirconium alloys if more experimental data were available. The singular behaviour of the diffusion profiles in the α-phase during linear kinetics is particularly analyzed.This work is part of a programme to study the oxide-metal interface movement during vapour oxidation of Zircaloy-4 subjected to temperature transients. Knowledge of this is of vital importance for evaluating mechanical properties of fuel claddings during possible loss of coolant accidents in nuclear power reactors.     

Loud speech, conglomerate noise, and behavioral aftereffects.

On the basis of a recent model of information overload, it was predicted that loud speech, conglomerate noise, and tasks requiring attention would produce behavioral aftereffects in the form of lowered frustration tolerance and reduced cognitive complexity. This prediction was confirmed by the results of a laboratory experiment in which 80 undergraduate females were exposed to varying levels of background noise (43 vs 80 db), the presence or absence of loud (80 db) speech, and tasks requiring recall. Results indicate that loud speech, conglomerate noise, and taxing reduce an individual's ability to tolerate frustration and to differentiate among people occupying different roles. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)