Synthesis of C‐Glucosylated Octaketide Anthraquinones in Nicotiana benthamiana by Using a Multispecies‐Based Biosynthetic Pathway

Carminic acid is a C‐glucosylated octaketide anthraquinone and the main constituent of the natural dye carmine (E120), possessing unique coloring, stability, and solubility properties. Despite being used since ancient times, longstanding efforts to elucidate its route of biosynthesis have been unsuccessful. Herein, a novel combination of enzymes derived from a plant (Aloe arborescens, Aa), a bacterium (Streptomyces sp. R1128, St), and an insect (Dactylopius coccus, Dc) that allows for the biosynthesis of the C‐glucosylated anthraquinone, dcII, a precursor for carminic acid, is reported. The pathway, which consists of AaOKS, StZhuI, StZhuJ, and DcUGT2, presents an alternative biosynthetic approach for the production of polyketides by using a type III polyketide synthase (PKS) and tailoring enzymes originating from a type II PKS system. The current study showcases the power of using transient expression in Nicotiana benthamiana for efficient and rapid identification of functional biosynthetic pathways, including both soluble and membrane‐bound enzymes.     

Cerium insertion in 316L passive film: Effect on conductivity and corrosion resistance performances of metallic bipolar plates for PEM fuel cell application

A surface treatment to modify passive film properties formed on 316L stainless steel has been designed for bipolar plate application in PEMFC systems. This one is based on cerium insertion from electrochemical technique. The effect of this element addition on the composition of the passive films was evaluated by X-ray photoelectron spectroscopy (XPS) and low energy ion spectroscopy (LEIS). Potentiodynamic and potentiostatic curves, and electrochemical impedance spectroscopy (EIS) were used for the characterisation of the corrosion protection in simulated PEMFC media. Interfacial contact resistance (ICR) was also evaluated. Results highlight an increase of the polarisation resistance of the cerium treated sample at ambient temperature, and a good corrosion resistance in anodic and cathodic simulated media. An important diminution of the IRC is obtained (80% with respect to the reference), which is attributed to the enhancement of the passive layer conductivity of the processed sample. Surface analyses show a great enrichment of cerium in first atomic layers of the films, which explains the better conductivity observed by an increase of charge carrier density in the passive film.     

Model-based multivariable control of the drying of a thin sheet of fibres in a continuous infrared dryer

We developed an Internal Model Control (IMC) algorithm for drying a thin textile fabric, continuously passing through an electric infrared dryer, based on a reduced linear model of the drying dynamics. This model relates the controlled variables, the humidity and temperature of the web at the dryer outlet, to the manipulated variables, the electrical power supplied to the sources and the web speed through the dryer, and also to changes in the initial humidity of the web at the dryer inlet. The control algorithm was first tested by simulation using the model in regulation mode, and in set-point tracking mode, to vary the manipulated variables so as to maintain the controlled variables at their respective set-points when the inlet web temperature and humidity were changed. The performance under simulated operational conditions was compared to that of a conventional feedback proportional-integral (PI) controller coupled with a feedforward control. The IMC controller was then tested directly in regulation mode using a pilot scale infrared dryer, acting simultaneously on the manipulated variables, the emitter power and the web speed, to control the fabric temperature and humidity at the dryer outlet. The experimental results were compared with those from the above feedback-feedforward controller, on the pilot scale dryer. The results have indicated that the closed-loop stability of the process is assured simply by choosing a stable IMC controller. Also, such a controller does not require the design of specific compensators for the strong interactions between variables of the drying process.     

Interactive software for estimating the efficacy of non-isothermal heat preservation processes

The most commonly used methods to generate microbial inactivation curves are based on the assumptions that microbial mortality follows first order kinetics and that the temperature effect on the 'D value' or exponential rate constant is determined by the log linear model or the Arrhenius equation, respectively. However, many bacterial cells and spores follow the Weibull-Log Logistic (WeLL) model and software to simulate pasteurization and sterilization processes using this model has been available for some years as free downloadable programs written in MS Excel. According to this model, an organism's heat resistance parameters are T(c), a marker of the temperature level where the inactivation accelerates, k, the steepness of the Weibullian rate parameter in the lethal regime where T>T(c) and n, a measure of the semi logarithmic isothermal survival curve's concavity and its direction. Because the traditional first order kinetics is just a special case of the Weibullian model with n=1.0, the software is applicable to both linear and non-linear inactivation. Recently, Wolfram Research Inc., the maker of Mathematica, has made its interactive program Mathematica Player free downloadable software. A user, who need not have a copy of Mathematica, can view and download any of the numerous graphic demonstrations from the Wolfram Demonstrations Project web site, and continuously manipulate their dynamic parameters with sliders on the screen. One set of five such demonstrations allows the user to generate and adjust the temperature profile of heat processes, modify the targeted organism's Weibullian survival parameters and immediately observe the corresponding semi-logarithmic survival curve and the equivalent time at a reference temperature, which can also be manipulated by a slider. This free program enables food microbiologists, technologists and engineers to examine a large number of heat processing options and assess their potential safety implications. It can also serve as a training and educational tool in industry and academia.     

Expressing the equivalence of non‐isothermal and isothermal heat sterilization processes

Currently, the sterility of heat‐processed food and pharmaceuticals is assessed in terms of an F₀ value, based on the equivalence of the heat treatment to an isothermal process at a reference temperature. This F₀ value, however, has a meaning if, and only if, the inactivation kinetics of the targeted spores (or cells) follow a first‐order relationship and the temperature dependence of the D value, the reciprocal of the rate constant, is log‐linear. There is growing evidence that these conditions are not satisfied by many spores, including those of Clostridium botulinum and vegetative cells. Consequently, a replacement for the F₀ value is proposed in the form of a momentary equivalent time at the reference temperature based on the actual survival pattern of the spores, which need not be log‐linear. This equivalent time can be calculated together with the theoretical survival ratio in real time, thus enabling an operator to monitor the lethality of ongoing industrial heat processes. The concept is demonstrated with published survival data of C. botulinum, for which the Weibullian and log‐logistic models served as primary and secondary models, respectively. The safety factor according to the proposed method is in the number of added minutes of processing, beyond the theoretical time needed to reduce the survival ratio of the targeted spores or cells to a level that would produce practical (or commercial) sterility. Copyright © 2006 Society of Chemical Industry     

Addition of trace metals increases denitrification rate in closed marine systems

We investigated the effect of trace metals (Fe, Mn, Cu, Zn and Mo) on the denitrification unit at the Montreal Biodome. Two dosages of the five trace metals were tested on a denitrifying bacterial population which was extracted from the denitrification unit and cultured in 250 mL chemostats with artificial seawater. The low dosage showed a 20% increase in the denitrification rate whereas the high dosage had a more pronounced effect with a 250% increase. No increase in bacterial growth was observed, suggesting that the trace metals had an effect on the denitrification activity. When the trace metals were tested separately, only iron had a significant effect similar to the increase in the denitrification rate observed when the five trace metals were added. The combination of Fe and Mn caused a small but significant increase compared to the five trace metals. We then tested the effect of adding Fe, Mn and Cu to the denitrification unit at the Montreal Biodome. A high dosage of these trace metals showed a 250% increase in the denitrification rate, which went from 200 to 700 g NO(x)-N/d. Our results showed that the addition of trace metals is crucial for denitrification activities.     

Prediction of Temperature Profiles in Tumors and Surrounding Normal Tissues During Magnetic Induction Heating

The development and preliminary verification of a simple two-compartment model describing the thermal response of adjacent normal and cancerous tissues subjected to magnetic induction heating is presented. Analytical expressions were found for estimating the spatial temperature distributions in the system composed of a spherical tumor mass imbedded in a cylindrical normal tissue as a function of the field intensity and the tissue's physical, geometrical, and physiological characteristics. The conditions leading to preferential heating of the tumor are described.     

A study on differences in human perception between a real and an AR scene viewed in an OST‐HMD

With the recent growth in the development of augmented reality (AR) technologies, it is becoming important to study human perception of AR scenes. In order to detect whether users will suffer more from visual and operator fatigue when watching virtual objects through optical see‐through head‐mounted displays (OST‐HMDs), compared with watching real objects in the real world, we propose a comparative experiment including a virtual magic cube task and a real magic cube task. The scores of the subjective questionnaires (SQ) and the values of the critical flicker frequency (CFF) were obtained from 18 participants. In our study, we use several electrooculogram (EOG) and heart rate variability (HRV) measures as objective indicators of visual and operator fatigue. Statistical analyses were performed to deal with the subjective and objective indicators in the two tasks. Our results suggest that participants were very likely to suffer more from visual and operator fatigue when watching virtual objects presented by the OST‐HMD. In addition, the present study provides hints that HRV and EOG measures could be used to explore how visual and operator fatigue are induced by AR content. Finally, three novel HRV measures are proposed to be used as potential indicators of operator fatigue.     

Estimation of soil and crop parameters for wheat from airborne radar backscattering data in C and X bands

The study of radar backscattering signatures of wheat fields was investigated, using data collected on the Orgeval agricultural watershed (France) by the airborne scatterometer ERASME in C and X bands, HH and VV polarizations, at incidence angles from 15° to 45°, during two years for different soil moisture conditions with simultaneous ground-based measurements. A simple parameterization as water-cloud model with two driving parameters (the surface soil moisture and the plant water content) gives satisfactory results to estimate radar cross sections of wheat for a wide range of frequencies (C and X bands) and incidence angles (20° and 40°) within 1 dB in CHH and XHH and 2 dB in CVV and XVV. At the lower frequency (C band) the attenuated soil backscattering by the vegetation is dominant. It is shown that simple linear relations in C band between radar cross section and soil moisture are insufficient. A correction term for the vegetation attenuation is needed and is determined. Low contrast between the backscattering of dry and wet soil (around 6 dB) for a given vegetation density leads to a relatively high error in the estimation of soil moisture by radar (0.06 cm³ / cm³). At the higher frequency (X band), the radar backscattering is negatively correlated to the vegetation water content with a saturation of the radar cross section as the plant grows (about 6 dB of dynamic range between low and fully grown canopy) with no dependence on the soil signal. The achievable accuracy in the estimation of crop water content is the same at 20° and 40° and higher in XHH (about 0.5 kg/m²) than in XVV.     

Camera Control in Computer Graphics

Recent progress in modelling, animation and rendering means that rich, high fidelity virtual worlds are found in many interactive graphics applications. However, the viewer's experience of a 3D world is dependent on the nature of the virtual cinematography, in particular, the camera position, orientation and motion in relation to the elements of the scene and the action. Camera control encompasses viewpoint computation, motion planning and editing. We present a range of computer graphics applications and draw on insights from cinematographic practice in identifying their different requirements with regard to camera control. The nature of the camera control problem varies depending on these requirements, which range from augmented manual control (semi‐automatic) in interactive applications, to fully automated approaches. We review the full range of solution techniques from constraint‐based to optimization‐based approaches, and conclude with an examination of occlusion management and expressiveness in the context of declarative approaches to camera control.