Improving Atmospheric Plasma Spraying of Zirconate Thermal Barrier Coatings Based on Particle Diagnostics

Lanthanum zirconate (La₂Zr₂O₇) has been proposed as a promising material for thermal barrier coatings. During atmospheric plasma spraying (APS) of La₂Zr₂O₇ a considerable amount of La₂O₃ can evaporate in the plasma flame, resulting in a non-stoichiometric coating. As indicated in the phase diagram of the La₂O₃-ZrO₂ system, in the composition range of pyrochlore structure, the stoichiometric La₂Zr₂O₇ has the highest melting point and other compositions are eutectic. APS experiments were performed with a TriplexPro?-200 plasma torch at different power levels to achieve different degrees of evaporation and thus stoichiometry. For comparison, some investigations on gadolinium zirconate (Gd₂Zr₂O₇) were included, which is less prone to evaporation and formation of non-stoichiometry. Particle temperature distributions were measured by the DPV-2000 diagnostic system. In these distributions, characteristic peaks were detected at specific torch input powers indicating evaporation and solidification processes. Based on this, process parameters can be defined to provide stoichiometric coatings that show good thermal cycling performance.     

Experimental and numerical investigation on development of new incremental forming process

The main subject of the present work is to present the new and innovative manufacturing technology based on the incremental forming approach. The idea is to develop a deformation process that is strictly based on small incremental deformations realized by a series of thin anvils. To realise this idea in practise this idea, a proper geometry of the upper die has to be designed. In the present work it is a set of several rolls (pressure rollers) that moves down towards a series of small anvils and performs rotational movement at the same time. As a result, the pressure is not transferred by the upper die directly to the material. The pressure is transferred to the sample through the series of thin anvils. To incrementally transfer the desired final shape to the forging a series of anvils with various lengths has to be used. Due to the complexity and novelty of the proposed approach, a set of questions has to addressed. These are related to appropriate depth of anvil indentation, material flow under a single anvil, material interaction with anvils and interaction between subsequent anvils. This basic research is done in the present work with the use of simple laboratory tests. Then detailed experimental analysis of material flow in the developed new process is presented. At this stage of the research the prototype of the proposed device is created on the basis of the orbital Marciniak forging press (Marciniak, 1970). All the obtained results are presented, and conclusions related to the effectiveness of the process are highlighted. The experimental part of the research is also supported by numerical analysis. The commercial finite element (FE) Forge2005 software was used in the present work to evaluate the forging process parameters and analyze the character of material deformation. The obtained numerical results are compared with the experimental analysis performed on the developed prototype press.     

The Interactions Between Rapeseed Lipoxygenase and Native Polyphenolic Compounds in a Model System

The focus of the present research was to study inhibition of lipoxygenase activity by rapeseed native polyphenols and the interactions between those compounds and the enzyme. The enzyme and polyphenolic compounds (polyphenols, phenolic acids) were extracted from rapeseed (Brassica napus) varieties Aviso and PR45DO3. The total phenolic compounds concentration in tested rapeseed was 1,485–1,691 mg/100 g d.m. (dry matter) and the free phenolic acids content in both rapeseed varieties was about 76 μg/100 g d.m. The isolated proteins showed lipoxygenase activity. Prooxidant properties of phenolic compounds in the presence of lipoxygenase and linoleic acid were observed rather in the case of extracts containing a relatively high concentration of miscellaneous polyphenols. Antioxidant properties were recorded in the case of phenolic acid extracts which contain only 1.4–1.9% of phenolics present in raw phenolic extracts. We propose that the prooxidant effect of phenolic compounds comes from quinone and oxidized polyphenols formation. The observed antioxidant activity of phenolic acid extracts is probably due to their ability to scavenge free radicals formed from linoleic acid. However, reduction of lipoxygenase ferric to ferrous ions, which prevent the activation of the enzyme and inhibited its activity, was also observed.     

Increasing the security of the ping–pong protocol by using many mutually unbiased bases

In this paper we propose an extended version of the ping–pong protocol and study its security. The proposed protocol incorporates the usage of mutually unbiased bases in the control mode. We show that, by increasing the number of bases, it is possible to improve the security of this protocol. We also provide the upper bounds on eavesdropping average non-detection probability and propose a control mode modification that increases the attack detection probability.     

Computer-Aided Design of Manufacturing Chain Based on Closed Die Forging for Hardly Deformable Cu-Based Alloys

Two copper-based alloys were considered, Cu-1 pct Cr and Cu-0.7 pct Cr-1 pct Si-2 pct Ni. The thermal, electrical, and mechanical properties of these alloys are given in the paper and compared to pure copper and steel. The role of aging and precipitation kinetics in hardening of the alloys is discussed based upon the developed model. Results of plastometric tests performed at various temperatures and various strain rates are presented. The effect of the initial microstructure on the flow stress was investigated. Rheologic models for the alloys were developed. A finite element (FE) model based on the Norton–Hoff visco-plastic flow rule was applied to the simulation of forging of the alloys. Analysis of the die wear for various processes of hot and cold forging is presented as well. A microstructure evolution model was implemented into the FE code, and the microstructure and mechanical properties of final products were predicted. Various variants of the manufacturing cycles were considered. These include different preheating schedules, hot forging, cold forging, and aging. All variants were simulated using the FE method and loads, die filling, tool wear, and mechanical properties of products were predicted. Three variants giving the best combination of forging parameters were selected and industrial trials were performed. The best manufacturing technology for the copper-based alloys is proposed.     

Influence of pH and ethanol on malolactic fermentation and volatile aroma compound composition in white wines

The present study investigated the influences of pH and ethanol on malolactic fermentation (MLF) and the volatile aroma profile of the subsequent white wines from Riesling and Chardonnay inoculated with two different Oenococcus oeni strains. In all cases MLF was induced after completion of alcoholic fermentation (AF). Partial MLF occurred under low pH 3.2 and high alcohol (118.3 g/L) conditions. In the cases with complete MLF, the time required for each strain varied from 13 to 61 days and was dependent on bacterial culture, cultivar and wine parameter. Chemical properties of each wine were determined after AF, complete and partial MLF. The wines showed significant differences in total higher alcohols, esters and acids that are important for the sensory profile and quality of wine. This work demonstrated that the wine matrix as well as the pH and alcohol concentration affects MLF and the final volatile aroma profile. Results indicate that changes in volatile aroma composition are not necessarily related to complete MLF and that partial MLF already has distinct influences on the wine aroma profile of white wines.     

Experimentally feasible measures of distance between quantum operations

We present two measures of distance between quantum processes which can be measured directly in laboratory without resorting to process tomography. The measures are based on the superfidelity, introduced recently to provide an upper bound for quantum fidelity. We show that the introduced measures partially fulfill the requirements for distance measure between quantum processes. We also argue that they can be especially useful as diagnostic measures to get preliminary knowledge about imperfections in an experimental setup. In particular we provide quantum circuit which can be used to measure the superfidelity between quantum processes. We also provide a physical interpretation of the introduced metrics based on the continuity of channel capacity.     

Enantioselective Synthesis of α‐Hydroxy Ketones via Benzaldehyde Lyase‐Catalyzed C−C Bond Formation Reaction

(R)‐Benzoins and (R)‐2‐hydroxypropiophenone derivatives are formed on a preparative scale by benzaldehyde lyase (BAL)‐catalyzed C−C bond formation from aromatic aldehydes and acetaldehyde in aqueous buffer/DMSO solution with remarkable ease in high chemical yield and high optical purity. The substrate range of this thiamin diphosphate‐dependent enzyme was examined with respect to a broad applicability of this benzoin condensation‐type reaction in stereoselective synthesis.     

Catalyzed Reactions of Enol Ethers with SN1 Active Groups: A Novel Method for the Preparation of α‐Alkylated Ketones

The performance of tert‐alkylations, alkoxyalkylations, and aldehyde enolate allylations proceeding with low catalyst loading (0.1 mol %–5 mol %) is described. The reactions are complete within short times and can even be performed without solvent and under ambient conditions. The mechanism of the reaction was investigated by deuterium labeling and cross‐over studies.