Trehalose improves flavour retention in dehydrated apricot puree

The influence of the addition of two sugars (trehalose and sucrose) on the retention of volatiles responsible for the characteristic aroma in dehydrated apricot puree was studied. Aroma compounds of fresh and both freeze‐dried and foam‐mat‐dried apricot puree were analysed by manual headspace solid‐phase microextraction coupled with gas chromatography (GC‐FID and GC‐MS). The best retention of aroma compounds in dehydrated apricot puree was obtained when trehalose was added, regardless of the dehydration process used (freeze drying or foam‐mat drying), although, generally, a much higher retention of flavour volatiles was obtained in freeze‐dried purees. Principal Component Analysis and Cluster Analysis were applied to all the apricot purees studied to obtain a simplified view of the relationship among the aroma compounds in dehydrated apricot purees. This study gives further insights into the mechanisms that occur when trehalose is applied as an additive and will enable the development of new processes to maximize this effect and to produce superior dried products.     

Electromagnetic Fields and Induced Voltages on Underground Pipeline in the Vicinity of AC Traction System

Various regulations, aimed at the protection of human beings and electrical equipment against possible adverse effects resulting from exposure to electromagnetic fields, have been issued in many countries. Most of them are based on safety guidelines published by international expert groups. In this paper, electric and magnetic fields are calculated in the vicinity of 25 kV traction line supplying railway traction systems. Calculation results are compared to exposure limits specified by safety guidelines and regulations. Possible countermeasures for reduction of electromagnetic fields are proposed. Also, this paper presents a method for calculation of the induced voltages to an underground gas pipeline from a neighbouring 25 kV electric traction overhead line in case of short circuit. Calculations are performed with EMTP-ATP software. Possible countermeasures for reduction of induced voltages are proposed.     

Electrocatalytic effects of Mo–Pt intermetallics singly and with ionic activators. Hydrogen production via electrolysis

The intermetallic phases along the Pt–Mo phase diagram, singly or in combination with specific ionic activators, have been investigated as cathode materials for the production of hydrogen by electrolysis from water KOH solutions in an attempt to decrease energy consumption. The influence of ionic activators (activating compounds) on energy consumption was significant. The intermetallic phases, as cathode materials, were activated by the surface deposition of activating compounds from electrolyte. The influence of these cathode materials on the electrolytic evolution of hydrogen was discussed in the context of transition metals features and their electronic configuration.     

Enantioselective cross-coupling of anhydrides with organozinc reagents: the controlled formation of carbon-carbon bonds through the nucleophilic interception of metalacycles

The construction of carbon-carbon bonds, particularly with concomitant control of newly formed asymmetric centers, is of paramount importance for the development of synthetic routes to complex organic molecules. While cross-coupling reactions for the generation of sp(2) carbon centers are well established, similar methodology for the formation and control of sp(3)-hydridized carbon stereocenters is extremely limited. We suggest that the nucleophilic interception of metalacycles provides the means to achieve such a transformation, wherein the metal complex serves to activate electrophiles, facilitate nucleophile addition, and ultimately control stereochemistry. One means of accessing these intermediates is through the use of simple meso-carboxylic anhydrides, which upon reaction with transition metals readily generate the desired metalacycles. Interception of the metalacycle with an appropriate carbon-based nucleophile generates an enantioenriched ketoacid, the product of the asymmetric desymmetrization of achiral starting materials. Early successes with achiral nickel catalysts and organozinc reagents provided the foundations for our approach. Alkylation of both succinic and glutaric anhydrides proceeds with a wide range of organozinc nucleophiles, forming 1,4- and 1,5-ketoacids in excellent yields. This reaction manifold has been extensively examined with a detailed kinetic study and mechanistic investigations utilizing mixed zinc reagents and alkene directing groups. This work has highlighted a number of unusual phenomena, including rate-limiting reductive elimination to form an sp(3)-sp(2) carbon-carbon bond. Despite excellent results with the achiral system, to date, all efforts to render the nickel-catalyzed reaction asymmetric have been limited to modest success. Palladium and rhodium complexes, with the use of chiral P-P and P-N ligands, respectively, have been identified as competent catalysts for the enantioselective addition of organozinc reagents to anhydrides. The arylation of a series of succinic anhydrides with Ph2Zn can be achieved in greater than 95% enantioselectivity using a Pd/Josiphos catalyst. Rhodium catalysts have proven amenable for the incorporation of in situ formed organozinc reagents, nucleophiles traditionally troublesome in transition metal catalysis due to the deleterious effects of residual halide ions. Highly functionalized organozinc nucleophiles, including those containing indole and furan, participate in this chemistry to provide the corresponding 1,4- and 1,5-ketoacids in excellent yield with greater than 85% enantioselectivity. This metalacycle interception methodology is currently being expanded to the use of other systems, most notably the asymmetric [2 + 2 + 2] cycloaddition of alkenes, alkynes, and isocyanates. Ongoing studies promise the extension of existing methodology toward the development of modular, fully intermolecular three-component couplings in which both metalacycle formation and nucleophilic interception can be controlled. Ultimately, we envision the use of heterocumulenes in such methodology, providing a route to complex products utilizing CO2 as an inexpensive C1 feedstock.     

Estimation of steel guitar strings corrosion by artificial neural network

The purpose of this work was to estimate the corrosion of steel guitar strings in the artificial sweat solution by applying artificial neural network (ANN). Measurements were conducted during 1, 2, 3 and 4 weeks. The results were used for training the most appropriate model of ANN. For evaluating the method efficiency, the comparison between measured data has been compared to values estimated by ANN. The high correlation coefficient and low mean absolute error between measured and estimated output values were observed. Therefore it can be concluded that ANN are promising tool for estimation of corrosion processes.     

About regression-kriging: From equations to case studies

This paper discusses the characteristics of regression-kriging (RK), its strengths and limitations, and illustrates these with a simple example and three case studies. RK is a spatial interpolation technique that combines a regression of the dependent variable on auxiliary variables (such as land surface parameters, remote sensing imagery and thematic maps) with simple kriging of the regression residuals. It is mathematically equivalent to the interpolation method variously called “Universal Kriging” (UK) and “Kriging with External Drift” (KED), where auxiliary predictors are used directly to solve the kriging weights. The advantage of RK is the ability to extend the method to a broader range of regression techniques and to allow separate interpretation of the two interpolated components. Data processing and interpretation of results are illustrated with three case studies covering the national territory of Croatia. The case studies use land surface parameters derived from combined Shuttle Radar Topography Mission and contour-based digital elevation models and multitemporal-enhanced vegetation indices derived from the MODIS imagery as auxiliary predictors. These are used to improve mapping of two continuous variables (soil organic matter content and mean annual land surface temperature) and one binary variable (presence of yew). In the case of mapping temperature, a physical model is used to estimate values of temperature at unvisited locations and RK is then used to calibrate the model with ground observations. The discussion addresses pragmatic issues: implementation of RK in existing software packages, comparison of RK with alternative interpolation techniques, and practical limitations to using RK. The most serious constraint to wider use of RK is that the analyst must carry out various steps in different software environments, both statistical and GIS.     

The potential of immersive virtual reality for representations in design education

Virtual Reality - This paper examines the potential of immersive virtual reality technology for design education. A quasi-experimental study has been conducted with 40 students of different...