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.     

Water Balance of the Upper Jordan River Basin

Sharing water in the Jordan basin has been a key topic in the recent peace talks between Israel and its neighbors. Knowing the quantity of water available is a prerequisite to water sharing. Many different values have been published in recent years. Different sources report Jordan's discharge flow into Lake Kinneret anywhere from 460 to 800 Mm³/year. The aim of this article is to present a water balance for the Jordan basin for a 15-year period. The years 1977–1978 to 1991–1992 were studied for the basin's water budget, as they represent the present day (1998) land use. The results show that Lake Kinneret has a yearly average input (= output) of 770 Mm³. Israel uses some 800 Mcm³/year from the entire Jordan basin, of which 440 Mm³ is used within the basin and the rest outside. There is about 100 Mm³ for future utilization in the watershed. The yearly Jordan's discharge to the Dead Sea is 220–250 Mm³. Reporting by various secondary data sources is compared to primary data findings to illustrate the great variability of data reporting and to provide annual flow estimates, based largely on primary sources, for the Upper Jordan River.     

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     

XPS studies of perovskites surface instability caused by Ar+ ion and electron bombardment and metal deposition

X-ray Photoelectron Spectroscopy (XPS) was used to study the influence of low energy Ar⁺ ion bombardment, electron bombardment and Pt deposition on the SrTiO₃ (STO) single crystal electronic structure. Atomic composition changes were found and attributed to chemical reconstruction of the STO surface. A clear correlation between the presence of conducting, low Ti oxidation states in valence band and core level changes was detected. A strong effect caused by electron irradiation was ascribed to the electroreduction process. The influence of lanthanum doping on surface instability of STO was also discussed. The La doped sample (STO: 3,75% La) was found to be modified upon Pt metal deposition to a higher degree than pure STO crystal.     

Quantifier-free logic for nondeterministic theories

We develop a quantifier-free logic for deriving consequences of multialgebraic theories. Multialgebras are used as models for nondeterminism in the context of algebraic specifications. They are many sorted algebras with set-valued operations. Formulae are sequents over atoms allowing one to state set-inclusion or identity of 1-element sets (determinacy). We introduce a sound and weakly complete Rasiowa–Sikorski (R–S) logic for proving multialgebraic tautologies. We then extend this system for proving consequences of specifications based on translation of finite theories into logical formulae. Finally, we show how such a translation may be avoided—introduction of the specific cut rules leads to a sound and strongly complete Gentzen system for proving directly consequences of specifications. Besides giving examples of the general techniques of R–S and the specific cut rules, we improve the earlier logics for multialgebras by providing means to handle empty carriers (as well as empty result-sets) without the use of quantifiers, and to derive consequences of theories without translation into another format and without using general cut.     

Description of adsorption of polar substances on microporous adsorbents using the modified Polanyi-Dubinin potential theory

Mechanism of adsorption of lower aliphatic alcohols and amines on active carbon surfaces has been studied. Interpretation of the results required application of the modified Polanyi-Dubinin potential theory. A basic difference in adsorption of alcohols and amines has been found. Thus, the degree of alcohols association is lower in the adsorbed phase than in the liquid phase, whereas the reverse is observed for amines.     

AdROSA—Adaptive personalization of web advertising

One of the greatest and most recent challenges for online advertising is the use of adaptive personalization at the same time that the Internet continues to grow as a global market. Most existing solutions to online advertising placement are based on demographic targeting or on information gained directly from the user. The AdROSA system for automatic web banner personalization, which integrates web usage and content mining techniques to reduce user input and to respect users’ privacy, is presented in the paper. Furthermore, certain advertising policies, important factors for both publishers and advertisers, are taken into consideration. The integration of all the relevant information is accomplished in one vector space to enable online and fully personalized advertising.     

Regularization of the inverse heat conduction problem by the discrete Fourier transform

Two methods of solving the inverse heat conduction problem with employment of the discrete Fournier transform are presented in this article. The first one operates similarly to the SVD algorithm and consists in reducing the number of components of the discrete Fournier transform which are taken into account to determine the solution to the inverse problem. The second method is related to the regularization of the solution to the inverse problem in the discrete Fournier transform domain. Those methods were illustrated by numerical examples. In the first example, an influence of the boundary conditions disturbance by a random error on the solution to the inverse problem (its stability) was examined. In the second example, the temperature distribution on the inner boundary of the multiply connected domain was determined. Results of calculations made in both ways brought very good outcomes and confirm the usefulness of applying the discrete Fournier transform to solving inverse problems.