Copper content of vineyard soils at Sremski Karlovci (Vojvodina Province,Serbia) as affected by the use of copper-based fungicides

The present study investigated the copper content of nine vineyard plots soils and four control plots as affected by the application of copper-based fungicides. The study was carried out at the site of Sremski Karlovci in the Serbian province of Vojvodina. The results showed that Cu soil concentrations are increased at the site and that there is a tendency towards soil contamination by this element. Of the 27 total samples studied, only one had Cu concentration above the maximum allowable concentration of 100?mg?kg^?1. That sample's concentration was 111.7?mg?kg^?1. All the samples from the 0–15?cm layer had copper levels that were above the critical value of 60?mg?kg^?1. The mean value of the samples was 79.4?mg?kg^?1, contrasting with the background concentration of 19.8?mg?kg^?1. The results obtained for the studied vineyard soils indicate that these soils are potentially at risk and call for reduced application of Cu-based fungicides along with soil monitoring.     

Demasking large dummy effects approach in revealing important interactions in Plackett–Burman experimental design

This paper presents a newly developed demasking large dummy effects (DDE) approach for identification of significant factor interactions in Plackett–Burman experimental design. Dummy factors, as imaginary factors, are not expected to contribute to the model, so the appearance of their high effect values could indicate the significance of the interactions they are confounded with. DDE approach consists of the screening of the large estimable effects, the calculation of the interactions that contribute the most to the large dummy effects from the alias matrix, and a single pass of all subsets regressions including preselected interactions and main factors for the final model tuning. Tested on experimentally obtained data from a robustness analysis of a method for the determination of raloxifene and its four impurities, DDE approach showed to create the models that have greater statistical power than the ones described with the main factors only, which makes them more reliable and accurate for the application. Additionally, because of the interactions selection criterion and final tuning phase of the strategy, DDE approach allows the creation of models that are likely to better describe the real systems, which increases the practical value. Copyright © 2012 John Wiley & Sons, Ltd.     

Assessment of β-lactams retention in hydrophilic interaction chromatography applying Box-Behnken design

In this paper, the retention prediction models for mixture of β-lactam antibiotics analyzed by hydrophilic interaction chromatography (HILIC) are presented. The aim of the study was to investigate the retention behavior of some organic acids and amphoteric compounds including cephalosporins (cefotaxime, cefalexin, cefaclor, cefuroxime, and cefuroxime axetil) and penicillins (ampicillin and amoxicillin). Retention of substances with acidic functional group in HILIC is considered to be interesting since the majority of publications in literature are related to basic compounds. In the beginning of the study, classical silica columns were chosen for the retention analysis. Then, preliminary study was done and factors with the most significant influence on the retention factors were selected. These factors with the impact on the retention factors were investigated employing Box-Behnken design as a tool. On the basis of the obtained results the mathematical models were created and tested using ANOVA test and finally verified. This approach enables the presentation of chromatographic retention in many ways (three-dimensional (3-D) graphs and simple two-dimensional graphical presentations). All of these gave the possibility to predict the chromatographic retention under different conditions. Furthermore, regarding the structure of the analyzed compounds, the potential retention mechanisms in HILIC were suggested.     

Avoiding the False Negative Results in LC Method Robustness Testing by Modifications of the Algorithm of Dong and Dummy Factor Effects Approach

The algorithm of Dong and error estimation based on a priori declared negligible effects (dummy factor effects approach) were evaluated for testing robustness, in case they provide contradictory results. Robustness of LC method for separation of ropinirole and its impurity was determined. Plackett–Burman design was applied to unravel the significant/influential factors. Four selected responses (retention factor of ropinirole and impurity, selectivity and resolution) were analyzed by the standard algorithm of Dong and dummy factor effects approach. The interpretation of the results for retention factor of ropinirole and resolution was inconclusive, since the two applied approaches identified different significant factors. The potential false negative or false positive results were avoided reanalyzing the results by the modified approaches. Modification of the dummy factor effects approach included omitting the large dummy effects values, and modification of the algorithm of Dong included calculating the margin of error values for all different number of factors included, and then selecting the lowest one to be the critical effect. The applied reanalysis allowed final important factor identification and non-significant intervals for significant effects calculation.     

Isomer separation and gas-phase configurations of organoruthenium anticancer complexes: Ion mobility mass spectrometry and modeling

We have used ion mobility-mass spectrometry combined with molecular modeling for the separation and configurational analysis of three low-molecular-weight isomeric organoruthenium anticancer complexes containing ortho-, meta-, or para-terphenyl arene ligands. The isomers were separated using ion mobility based on traveling-wave technology and the experimentally determined collision cross sections were compared to theoretical calculations. Excellent agreement was observed between the experimentally and theoretically derived measurements.     

Fuzzy control strategies in human operator and sport modeling

The motivation behind mathematically modeling the human operator is to help explain the response characteristics of the complex dynamical system including the human manual controller. In this paper, we present two different fuzzy logic strategies for human operator and sport modeling: fixed fuzzy-logic inference control and adaptive fuzzy-logic control, including neuro-fuzzy-fractal control. As an application of the presented fuzzy strategies, we present a fuzzy-control based tennis simulator.     

Light‐Gated Synthetic Protocells for Plasmon‐Enhanced Chemiosmotic Gradient Generation and ATP Synthesis

Herein, we present a light‐gated protocell model made of plasmonic colloidal capsules (CCs) assembled with bacteriorhodopsin for converting solar energy into electrochemical gradients to drive the synthesis of energy‐storage molecules. This synthetic protocell incorporated an important intrinsic property of noble metal colloidal particles, namely, plasmonic resonance. In particular, the near‐field coupling between adjacent metal nanoparticles gave rise to strongly localized electric fields and resulted in a broad absorption in the whole visible spectra, which in turn promoted the flux of photons to bacteriorhodopsin and accelerated the proton pumping kinetics. The cell‐like potential of this design was further demonstrated by leveraging the outward pumped protons as “chemical signals” for triggering ATP biosynthesis in a coexistent synthetic protocell population. Hereby, we lay the ground work for the engineering of colloidal supraparticle‐based synthetic protocells with higher‐order functionalities.     

Influence of Defects on the Stability and Hydrogen-Sorption Behavior of Mg-Based Hydrides

This review deals with the destabilization methods for improvement of storage properties of metal hydrides. Both theoretical and experimental approaches were used to point out the influence of various types of defects on structure and stability of hydrides. As a case study, Mg, and Ni based hydrides has been investigated. Theoretical studies, mainly carried out within various implementations of DFT, are a powerful tool to study mostly MgH₂ based materials. By providing an insight on metal-hydrogen bonding that governs both thermodynamics and hydrogen kinetics, they allow us to describe phenomena to which experimental methods have a limited access or do not have it at all: to follow the hydrogen sorption reaction on a specific metal surface and hydrogen induced phase transformations, to describe structure of phase boundaries or to explain the impact of defects or various additives on MgH₂ stability and hydrogen sorption kinetics. In several cases theoretical calculations reveal themselves as being able to predict new properties of materials, including the ways to modify Mg or MgH₂ that would lead to better characteristics in terms of hydrogen storage. The influence of ion irradiation and mechanical milling with and without additives has been discussed. Ion irradiation is the way to introduce a well-defined concentration of defects (Frankel pairs) at the surface and sub-surface layers of a material. Defects at the surface play the main role in sorption reaction since they enhance the dissociation of hydrogen. On the other hand, ball-milling introduce defects through the entire sample volume, refine the structure and thus decrease the path for hydrogen diffusion. Two Severe Plastic Deformation techniques were used to better understand the hydrogenation/dehydrogenation kinetics of Mg- and Mg₂Ni-based alloys: Equal-Angular-Channel-Pressing and Fast-Forging. Successive ECAP passes leads to refinement of the microstructure of AZ31 ingots and to instalment therein of high densities of defects. Depending on mode, number and temperature of ECAP passes, the H-sorption kinetics have been improved satisfactorily without any additive for mass H-storage applications considering the relative speed of the shaping procedure. A qualitative understanding of the kinetic advanced principles has been built. Fast-Forging was used for a “quasi-instantaneous” synthesis of Mg/Mg₂Ni-based composites. Hydrogenation of the as-received almost bi-phased materials remains rather slow as generally observed elsewhere, whatever are multiple and different techniques used to deliver the composite alloys. However, our preliminary results suggest that a synergic hydrogenation / dehydrogenation process should assist hydrogen transfers from Mg/Mg₂Ni on one side to MgH₂/Mg₂NiH₄ on the other side via the rather stable a-Mg₂NiH_0.3, acting as in-situ catalyser.     

Multi-Level Robustness Evaluation Approach: From Robustness Criterion to Adapted Algorithm of Dong

This paper proposes an innovative concept for robustness evaluation guided by two crucial aims: indubitable identification of the factors that significantly affect the LC method and avoidance of unnecessary time and money wasting. The first phase of the proposed strategy includes robustness screening during the method optimization. Initial assumptions of the method robustness can be tracked as the rate of the response change while the factors deviate within the expected range. Therefore, partial and total robustness criteria are calculated. If the results obtained are not satisfactory, re-optimization of the method should be considered. Otherwise, extensive robustness testing defined by experimental design and multi-level factors estimation should be performed to confirm the method robustness. Firstly, the important factors are investigated by the standard graphical (normal probability plots) and statistical (algorithm of Dong and error estimation based on a priori declared negligible effects) procedures. Since these approaches have several drawbacks, they can result in the appearance of false negative or false positive results. Thus, the modification of the statistical tests is advised in order to make the final conclusions. Special attention was dedicated to the advantages of the adapted algorithm of Dong (so-called 75 % approach) in the absence of the effect sparsity. The new approach is presented on the optimization and robustness testing of LC method for determination of ramipril and its five impurities. It is proved that the proposed strategy can perform an overall robustness estimation and successfully reveal all important factors.