Advanced automation of a flow injection analysis system for quality control of olive oil through the use of a distributed expert system

A new methodology—based on the combination of flow injection analysis and a distributed expert system—is proposed for the on-line chemical quality control of olive oil. This knowledge-based system is in charge of carrying out the flow injection determination of total acidity, peroxide value, and UV spectrophotometric measurements (K₂₃₂ and K₂₇₀), according to EU legislation. On the other hand, the expert system, apart from supervising the correct functioning of the system (devices, clogging, analysis frequency, and so on), performs the definite classification of the analyzed oil by evaluating the oil quality from the values yielded, according to previously established specifications. Satisfactory results have been obtained in the application of this approach to different samples of Spanish olive oil along the storage process. The distributed expert system also allows for the remote control of the analysis process owing to the interconnection of the different nodes by means of a communication network.     

An expert system applied to the control of an industrial-scale bioreactor

Control of a fed-batch industrial-scale fermenter requires a large amount of “finger-tip feeling” on the part of operators, despite reasonably sophisticated instrumentation. The reason for this is that there are no applicable deterministic models giving aid to the control system in deciding the best operation strategies. This is a typical case of a heuristic experimental process, treating inexact knowledge that is excluded from deterministic and statistic modelling a priori. Essential parts of this problem can be solved by means of an expert system shell, capable of dealing with uncertain information, using the linguistic shell application. Knowledge was extracted from process records on fermentation batches producing baker's yeast on an industrial scale. A strategy for heuristically optimized yield and growth rate can be predicted using knowledge gained in previous runs and stored in the knowledge base of the expert system. The expert system, once built up, can also be used for experimental simulation of the effects of fundamental decision parameters: temperature, production rate, ethanol concentration and specific growth rate. The use of expert system consultations can be generally recommended as an efficient aid in fermentation control.     

How autoverification through the expert system VALAB can make your laboratory more efficient

For over 10 years now various expert systems have been on the market, but very few have reached the level of performance of Validation Assistée pour les Laboratoires d’Analyses Biologiques (VALAB). Over 25,000 rules are combined through an inference engine to reproduce human reasoning in the complex ”biological validation” process. After a review of the product concept and its development program, we will see how this ”intelligent” tool can bring quality to clinical laboratories, from a production as well as legislation point of view. With more than 140 laboratories using VALAB in Europe in daily routines, our designer and vendor experience in installation, maintenance, upgrading, reliability, efficiency, and liability is excellent. Received: 9 October 2001 Accepted: 22 July 2002 Presented at the European Conference on Quality in the Spotlight in Medical Laboratories, 7–9 October 2001, Antwerp, Belgium Correspondence to E. Rogari     

Measurement of discharge rate in a canal using radiotracer dilution technique

Measurement of discharge rates of fluids and solids is an essential requirement in industrial and environmental systems. Radiotracer techniques are widely used for measurement of fluids/solids in situations where conventional techniques cannot be applied. The present paper describes application of radiotracer dilution technique to measure the discharge rate of water in a canal with an objective to validate efficiency of the Concrete Volute Pump used for pumping water in the canal. ¹³¹I radioisotope having activity of 55.5 GBq was used as radiotracer. The discharge rate of water was measured to be 20.6 m³/s.     

Study of Lotka-volterra food chain chemostat with periodically varying dilution rate

In this paper, we introduce and study a model of Lotka-volterra chemostat food chain chemostat with periodically varying dilution rate, which contains with predator, prey, and substrate. We investigate the subsystem with substrate and prey and study the stability of the periodic solutions, which are the boundary periodic solutions of the system. The stability analysis of the boundary periodic solution yields an invasion threshold. By use of standard techniques of bifurcation theory, we prove that above this threshold there are periodic oscillations in substrate, prey, and predator. Simple cycles may give way to chaos in a cascade of period-doubling bifurcations. Furthermore, we numerically simulate a model with sinusoidal dilution rate, by comparing bifurcation diagrams with different bifurcation parameters, we can see that the system experiences following process: periodic solution → periodic doubling cascade → chaos.     

Photoinitiated polymerization reactions: Application of a new real-time FTIR system for following the rate of polymerization

During the development of a technique whereby the progress of cure in a photoinitiated polymerization reaction can be monitored by IR spectroscopy, a Fourier transform IR (FTIR) microscope was adapted to enable curing to be carried out on the microscope stage. Preliminary results are reported illustrating the effectiveness of the development for the observation of polymerization in acrylate, dioxolane and polymerizable liquid crystal systems.     

Towards a portable microchip system with integrated thermal control and polymer waveguides for real-time PCR

A novel real-time PCR microchip platform with integrated thermal system and polymer waveguides has been developed. The integrated polymer optical system for real-time monitoring of PCR was fabricated in the same SU-8 layer as the PCR chamber, without additional masking steps. Two suitable DNA binding dyes, SYTOX Orange and TO-PRO-3, were selected and tested for the real-time PCR processes. As a model, cadF gene of Campylobacter jejuni has been amplified on the microchip. Using the integrated optical system of the real-time PCR microchip, the measured cycle threshold values of the real-time PCR performed with a dilution series of C. jejuni DNA template (2 to 200 pg/microL) could be quantitatively detected and compared with a conventional post-PCR analysis (DNA gel electrophoresis). The presented approach provided reliable real-time quantitative information of the PCR amplification of the targeted gene. With the integrated optical system, the reaction dynamics at any location inside the micro reaction chamber can easily be monitored.     

Effect of dilution and correction of the count rate data in gamma scintillation counting

Serious errors could be introduced into experimental results due to the observed non-additive nature of the count rate data recorded by gamma scintillation counters, particularly when the samples are subjected to excessive dilution. Simple procedures for correcting the experimental results are suggested.     

Dynamic control of racemization rate through E-Z photoisomerization of azobenzene and subsequent partial photoresolution under circular polarized light

We have synthesized bicyclic azobenzene dimers that possess enantiomers whose racemization rates could be controlled reversibly through E-Z photoisomerization of the azobenzene units. Upon alternating the exposure to r- and l-CPL, we were able to repeatedly perform partial enrichment of (S)- and (R)- enantiomers, respectively.     

Advantages of a two-detector system in automated substoichiometric radioisotope dilution analysis

Automation widens the scope of substoichiometric radioisotope dilution analysis. This is because the very strict requirement of the manual method-chemical separation of exactly equal quantities of the test substance-need no longer be fulfilled: reproducibility of the determination is reached by means of automated operation and activity measurement. The theory given in this paper shows how the choice of suitable chemical reactions is widened and why the reliability and the advantages of isotope dilution analysis are secured by the use of a two-detector system.     

Hybrid atom transfer radical polymerization system for balanced polymerization rate and polymer molecular weight control

A hybrid polymerization system that combines the fast reaction kinetics of conventional free radical polymerization and the control of molecular weight and distribution afforded by ATRP has been developed. High‐free radical initiator concentrations in the range of 0.1–0.2 M were used in combination with a low concentration of ATRP catalyst. Conversions higher than 90% were achieved with ATRP catalyst concentrations of less than 20 ppm within 2 h for the hybrid ATRP system as compared with ATRPs where achieving such conversions would take up to 24 h. These reaction conditions lead to living polymerizations where polymer molecular weight increases linearly with monomer conversion. As in living polymerization and despite the fast rates and low ATRP catalyst concentrations, the polydispersity of the produced polymer remained below 1.30. Chain extension experiments from a synthesized macroinitiator were successful, which demonstrate the living characteristics of the hybrid ATRP process. Catalyst concentrations as low as 16 ppm were found to effectively mediate the growth of over 100 polymer chains per catalytic center, whereas at the same time negating the need for post polymerization purification given the low‐catalyst concentration. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2294–2301, 2010     

An in silico expert system for the identification of eye irritants

This report describes development of an in silico, expert rule-based method for the classification of chemicals into irritants or non-irritants to eye, as defined by the Draize test. This method was developed to screen data-poor cosmetic ingredient chemicals for eye irritancy potential, which is based upon exclusion rules of five physicochemical properties – molecular weight (MW), hydrophobicity (log P), number of hydrogen bond donors (HBD), number of hydrogen bond acceptors (HBA) and polarizability (Pol). These rules were developed using the ADMET Predictor software and a dataset of 917 eye irritant chemicals. The dataset was divided into 826 (90%) chemicals used for training set and 91 (10%) chemicals used for external validation set (every 10th chemical sorted by molecular weight). The sensitivity of these rules for the training and validation sets was 72.3% and 71.4%, respectively. These rules were also validated for their specificity using an external validation set of 2011 non-irritant chemicals to the eye. The specificity for this validation set was revealed as 77.3%. This method facilitates rapid screening and prioritization of data poor chemicals that are unlikely to be tested for eye irritancy in the Draize test.     

Development of an expert system rulebase for the prospective identification of photoallergens

Relationships between the structure and properties of chemicals can be programmed into knowledge-based systems such as DEREK (an acronym for 'Deductive Estimation of Risk from Existing Knowledge'). The DEREK knowledge-based computer system contains a sub-set of over 50 rules describing chemical substructures (toxophores) responsible for skin sensitization. This rulebase, based originally on Unilever historical in-house guinea pig maximisation test data, is largely complete and is undergoing refinement as the next stage of its development. As part of an ongoing program of validation and testing, the predictive ability of the sensitization rule set was assessed by processing the structures of over 100 chemical substances in the list of contact allergens identified by the BgVV (German Federal Institute for Health Protection of Consumers). The exercise highlighted areas of chemistry where further development of the rulebase was required, either by extension of the scope of existing rules or by generation of new rules where a sound mechanistic rationale for the biological activity could be established. Several chemicals likely to be acting as photoallergens were identified and rules for photoallergenicity were written covering three classes of chemicals. This paper describes work to extend the DEREK rules for photoallergenicity as part of the European Phototox Project.     

Blood as active colloid system: Study of blood sedimentation upon dilution of saline

Dependence of dynamics of blood sedimentation upon successive dilution of blood with saline solution in vitro was studied basing on the application of the principles of the system of technical vision. Oscillatory nature of the process of sedimentation of boundary between blood cells and plasma dependent on the degree of blood dilution with saline was found rate changes. The correlation between ESR (erythrocyte sedimentation rate) and the concentration of saline was determined.     

Enthalpies of dilution of aqueous electrolytes: The NaCl/H2O system

Analysis of enthalpy of dilution data for the system NaCl/H₂O at 298.15°K with correlating equations presently in widespread use shows that these do not satisfactorily fit the data at the lowest available concentrations. A new approach based on the extended Debye-Hückel theory is suggested. It is shown that a plot of the ratio of the apparent molar enthalpy of dilution to the change in ionic strength, L/I, versus (I _i ^1/2 –I _f ^1/2 )/I, should give a straight line at low enough concentration with a slope 2S _H/3. The intercept is related to the Debye distance parameterA and the coefficient of the first virial correction term. The quantityS _H is the limiting Debye slope as calculated from the properties of the pure solvent. These expectations are substantiated by the fits. Values of the parameters are compared with older estimates, and it is concluded that the choiceA=0 is reasonable.     

Implementation of an expert system for the qualitative interpretation of X-ray fluorescence spectra

The implementation of an expert system for the automated qualitative interpretation of energy-dispersive x-ray spectra is discussed. The first step in the interpretation process is the extraction of the relevant data from the spectrum, which is done by a preprocessor program, written in FORTRAN. The expert system itself consists of three parts. The knowledge base contains specific information on energy-dispersive x-ray fluorescence spectrometry presented in the form of IF/THEN rules. The data base contains the reduced spectral data and an array of certainty factors associated with each element; the certainty factor for an element represents the probability of its being present in the sample from which the spectrum was taken. Finally, the inference engine performs manipulation of the knowledge. For a particular state of the data base, the certainty factors for all the elements are iteratively modified until convergence is reached by using the rules from the knowledge base. During each cycle, the inference engine selects one rule from the knowledge base and executes it. Rules are selected on the basis of the chemical elements contained in their IF part and according to their previously assigned focus levels. Execution of the THEN part of the selected rule modifies the certainty factors of a number of elements. At the end of the interpretation session, the system lists the elements which have a high probability of being present in the sample. Optionally, the user can be provided with explanations of the reasoning steps taken during the interpretation. Application of the expert system to a particular spectrum shows that it is useful for the reliable interpretation of spectral data obtained from electron microprobe analysis of industrial aerosol particles.     

Prediction of the rodent carcinogenicity of 60 pesticides by the DEREKfW expert system

The two-year rodent bioassay represents the golden standard for evaluating the carcinogenicity of chemicals. Because of practical and ethical reasons, alternative approaches have been investigated for many years. Among these approaches, the (quantitative) structure-activity relationships [(Q)SARs] offer promising perspectives for quickly screening a large number of chemicals. To increase the acceptance of (Q)SARs among the regulators, their predictive power needs to be scientifically validated. In this article, we tested the capacity of the DEREKfW expert system to qualitatively predict the rodent carcinogenicity and the genotoxic potential of 60 pesticides recently registered in Switzerland. The percentage of false negatives was found to be 31% for carcinogenicity. The associated sensitivity of 69% indicates that most of the pesticides with positive rodent bioassay results were detected by DEREKfW. On the other hand, the low specificity of 47% indicates that many pesticides may be flagged as carcinogenic while rodent bioassays would not confirm this potential. This may lead to unnecessary testing or the unnecessary restriction of a chemical.     

Validation of a digestion system using a digester block/cold finger system for the determination of lead in vegetable foods by electrothermal atomic absorption spectrometry

This paper presents the validation of a system for sample digestion using a digester block/cold finger to determine the lead content in vegetables by electrothermal atomic absorption spectrometry (ETAAS). After mineralization, lead contents were determined by ETAAS using a calibration curve based on aqueous standards prepared in 2.60 M nitric acid solutions containing 5 microg ammonium phosphate as chemical modifier. A pyrolysis temperature of 900 degrees C and atomization temperature of 2000 degrees C were used. This method allowed the determination of lead with a characteristic mass of 35 pg; LOD and LOQ of 0.6 and 2 nglg, respectively, were found. The precision was investigated in terms of reproducibility and repeatability. Reproducibility was estimated by analysis of nine different portions of a certified reference material (CRM) of spinach leaves, and the repeatability was determined through the analysis of nine aliquots of the same solution. The reproducibility and repeatability were found to be 4.27 and 2.94% RSD, respectively. The accuracy was confirmed by analysis of whole meal flour, spinach leaves, and orchard leaves CRMs, all furnished by the National Institute of Standards and Technology. Lead contents were measured using the newly developed technique in 11 different potato samples. The lead contents ranged from 12.80 to 69.27 ng/g, with an average value of 28.59 ng/g. These values were in agreement with data reported in the literature.     

The inclusion of double-channel ultraviolet spectrophotometry in an expert system for pharmaceutical analysis

Different criteria are compared for the selection of optimal wavelengths in the u.v. spectrophotometry of pharmaceutical samples. The effect of over-determination on the precision and accuracy of the results is evaluated. It is concluded that for the commercial samples of tablets containing two active substances investigated, good results are obtained when the classical approach (measurems at λ_max) is applied and that no improvement is observed when over-determination is used. Rules are derived to include the two-component u.v. spectrophotometry in an expert system for pharmaceutical analysis.