Optimisation of osmotic dehydration process of guavas by response surface methodology and desirability function

Response surface methodology was used to assess the effects of osmotic solution concentration (40–60°Brix), process temperature (20–40 °C) and vacuum pulse application time (0–20 min) at 100 mbar on water loss (WL), weight reduction (WR), solid gain (SG), water activity (a_w), colour parameters and mechanical properties of guava slices. Optimal process conditions were determined through the desirability function approach and quality characteristics of osmotically dehydrated guavas were analysed. Only models obtained for WL, WR and a_w were suitable to describe the experimental data. The desirability function showed that optimal conditions for osmotic dehydration of guavas were: osmotic solution concentration at 60°Brix, process temperature at 32 °C and 20 min of vacuum pulse application. Under optimal conditions, colour and mechanical properties of treated guavas were similar to fresh fruit, presenting WL of 29.01 g/100 g, WR of 25.91 g/100 g, SG of 3.10 g/100 g and a_w of 0.979.     

Two‐Dimensional Model for Oxidative Coupling of Methane in a Packed‐Bed Membrane Reactor

A two‐dimensional (2D) model of a packed‐bed membrane reactor was developed to describe ethylene production by oxidative coupling of methane (OCM). The model covers all relevant energy and mass transport processes in the reactor and allows a more precise prediction of the temperature and conversion patterns. It is demonstrated that the fast OCM reaction leads to oxygen depletion in the vicinity of the membrane, causing strong radial concentration gradients in the bed. Further results indicate that the detailed 2D model can provide more accurate predictions of experimental data than the simplified one.     

Comparative effect of different test methodologies on Bacillus coagulans spores inactivation kinetics in tomato pulp under isothermal conditions

Heat resistant micro‐organisms are an ongoing challenge to the food industry. Various factors may influence the heat resistance of micro‐organisms including type and strain; the environmental influences during cell and spore formations and during heat exposure; and the equipment and test tools used to perform the experimental process. In an attempt to analyse the influence of different test tools used on the heat inactivation processes, this study aimed to define the isothermal inactivation kinetics of Bacillus coagulans spores in tomato pulp at different temperatures and compare the inactivation of this bacterium when thermal death time (TDT) and capillary tube methods were used. Temperature ranges from 95 °C to 120 °C were studied, and inactivation kinetic parameters were estimated through the application of primary models. TDT inactivation curves consisted of shoulder and linear decline, while capillary method inactivation curves consisted of shoulder, linear decline and long tail. A secondary model was used to describe the influence of the temperature on spore inactivation parameters. The results showed test methods are at least as important in determining thermal processes as the micro‐organisms and media used.     

High-end performance or outlier? Evaluating the tail of scientometric distributions

The present paper attempts to shed light on outstanding research performance using the example of citation distributions. In order to answer the question of how the analysis of outstanding performance, in general, and highly cited papers, in particular, could be integrated into standard techniques of evaluative scientometrics. Two general methods are proposed: One solution aims at quantifying the performance represented by the tail of citation distributions independently of the “mainstream”, the second one, a parameter-free solution, provides performance classes for any level. Advantages and shortcoming of both methods are discussed.     

Analysis of stable crack propagation in filled rubber based on a global energy balance

Stable crack propagation in filled rubber is investigated by means of experimental and finite element analyses. Based on an experimental evaluation of multiple specimens under different loading states, dissipation rates are computed by applying a global energy balance. The dissipation rates calculated analogously from results of a numerical simulation of the multiple specimen method are in good accordance with the experimental findings. A further comparison of simulation results evaluated on basis of the material force method with energy release rates computed by means of an energy balance of two crack states under fixed loading conditions shows that the measured fracture sensitivity values are mainly related to the development and increase of a dissipative zone.     

Using ‘core documents’ for the representation of clusters and topics

The notion of ‘core documents’, first introduced in the context of co-citation analysis and later re-introduced for bibliographic coupling, refers to the representation of the core of a publication set according to given criteria. In the present study, the notion of core documents is extended to the combination of citation-based and textual links. It is shown that core documents defined this way can be used to represent and describe document clusters and topics at different levels of aggregation. Methodology is illustrated using the example of two ISI Subject Categories selected from applied and social sciences.     

Synthesis,Catalytic Activity in Oxidation Reactions,and Recyclability of Stable Polyoxometalate‐Centred Dendrimers

Nine‐ and 27‐armed dendrimers with a peroxophosphotungstate core were synthesized by an ionic‐bonding approach and used as air‐stable, recoverable catalysts for oxidation reactions using hydrogen peroxide.