The High-Frequency Base Converter?A New Approach to Static High-Power Conversion

A new approach to high-power conversion in which two naturally commutated converters (cycloconverters) are used in tandem, each with its input connected to a (passive) high-frequency (HF) source (``base') is presented. The arrangement approximates an ideal converter; its ``input' and ``output' frequency can be equal or different, and the power factor at both external terminals can be maintained at unity or any other value. Potential utility applications in which the HF base converter functions as an asynchronous intertie between two ac power systems and as a tie between a dc transmission line and a weak ac system are discussed, and technical and economic comparisons with conventional approaches are given.     

Phase equilibria modelling in Bi–Sr–Co–O system—Towards crystal growth and melt-assisted material processing

In this contribution, high-temperature phase equilibria of the partly open Bi–Sr–Co–(O) system with oxygen content given by its activity in the surrounding atmosphere, were modelled based on the experimental phase diagram determined previously. For the assessment, we also used the previously reported thermodynamic data and phase equilibria for the quasibinary Bi–Co–(O), Sr–Co–(O) and Bi–Sr–(O) subsystems as well as the thermodynamic data of quaternary phases obtained from calorimetry and simultaneous thermal analysis. Namely, the oxide melt was described based on the Redlich-Kister parameters of the corresponding quasibinary systems and the solid oxides were considered as stoichiometric. Their heat capacity and entropy were determined from calorimetry and the enthalpy of formation was refined to reproduce their melting behaviour. The constructed phase diagram focused on solid-liquid equilibria is particularly important for designing the experiments of single crystal growth and melt assisted material processing of these highly significant cobaltites.     

Assessing Acute Toxicity of Selected Packages Internal Layers Extracts using Microtox®

In the scientific literature related to the widely understood issue of packaging materials designed to have contact with food (food contact materials), there is much information on raw materials used for their production, as well as their physiochemical properties, types and parameters. Unfortunately, not much attention is given to the issues concerning migration of toxic substances from packaging and its actual influence on the health of the final consumer, even though health protection and food safety are the priority tasks. The goal of this study was to estimate the impact of particular foodstuff packaging type, food production and storage conditions on the degree of leaching of potentially toxic compounds to foodstuffs with the use of the acute toxicity test Microtox^®. From all simulants studied, the 3% acetic acid in water proved to cause significant migration of toxic compounds with increase of time and temperature of extraction and justified the hypothesis that food products with low pH values (stored in cans) cause significant damage to cans internal resin filing and is a reason of increased migration rate of package material to foodstuff. Copyright © 2017 John Wiley & Sons, Ltd.     

Neuron Adhesion on Diamond: Competition between Polymer Treatment and Surface Morphology

The ability to form an efficient interface between material and neural cells is a crucial aspect for construction of neuroelectrodes. Diamond offers material characteristics that could, to a large extent, improve the performance of neuroelectrodes. The greatest advantage of diamond is a large variety of material and surface properties such as electrical conductivity, surface morphology, and surface chemistry. Such a variety of material characteristics can lead to various cellular responses. Here, the authors compare survival, adhesion, and neurite formation of primary neurons on diamond thin films of various morphologies and treatments with several types of polymers commonly used to enhance cell adhesion. The authors find that the variation of surface roughness of nanocrystalline diamond film when coated with polymer does not have a major influence on neuron survival or adhesion. The adhesion of neurons can be influenced by the selected type of polymer coating. High molecular weight of polyethylenimine results in lower viability, adhesion, and neurite formation. The addition of laminin to treated films do not lead to significant improvements in neuron adhesion and neurite development. Their findings emphasize the importance of the correct polymer treatment over morphological properties of diamond thin films as a material for forming interfaces with primary neurons.

     

Model of Genetic Code Structure Evolution under Various Types of Codon Reading

The standard genetic code (SGC) is a set of rules according to which 64 codons are assigned to 20 canonical amino acids and stop coding signal. As a consequence, the SGC is redundant because there is a greater number of codons than the number of encoded labels. This redundancy implies the existence of codons that encode the same genetic information. The size and organization of such synonymous codon blocks are important characteristics of the SGC structure whose evolution is still unclear. Therefore, we studied possible evolutionary mechanisms of the codon block structure. We conducted computer simulations assuming that coding systems at early stages of the SGC evolution were sets of ambiguous codon assignments with high entropy. We included three types of reading systems characterized by different inaccuracy and pattern of codon recognition. In contrast to the previous study, we allowed for evolution of the reading systems and their competition. The simulations performed under minimization of translational errors and reduction of coding ambiguity produced the coding system resistant to these errors. The reading system similar to that present in the SGC dominated the others very quickly. The survived system was also characterized by low entropy and possessed properties similar to that in the SGC. Our simulation show that the unambiguous SGC could emerged from a code with a lower level of ambiguity and the number of tRNAs increased during the evolution.     

An Automated Vibrating-Tube Densimeter for Measurements of Small Density Differences in Dilute Aqueous Solutions

The core of the automated apparatus is a high-temperature high-pressure densimeter with a metal vibrating tube designed for accurate flow measurements of densities of liquids in the temperature range from 298 to 573 K and at pressures from 0.1 MPa up to 30 MPa. The densimeter is being employed for a study of dilute solutions of aqueous solutions of organic substances where the density difference {solution–water} is a primary experimental quantity. Consequently, partial molar volumes of solutes at infinite dilution in water are evaluated from the measured data. Two sampling sections are connected in series in the filling line of the densimeter. One of them is employed for manual filling of the measured sample into a sampling loop using a syringe. The other section allows fully automated measurement of up to 12 samples in one run. The recorded data are evaluated after the automated run is completed.     

A quadratic time algorithm to maximize the number of just-in-time jobs on identical parallel machines

In this paper, we study a scheduling problem on identical parallel machines, in which a processing time and a due date are given for each job, and the objective is to maximize the number of just-in-time jobs. A job is called just-in-time if it is completed exactly on its due date. We discuss the known results, show that a recently published greedy algorithm for this problem is incorrect, and present a new quadratic time algorithm which solves the problem.     

State Behavior Database for Pure Liquids and Data Correlation

A database system designed for storage, maintenance, and evaluation of published experimental data related to the state behavior of pure liquids is described. The database system is maintained by a program package (FoxPro) that allows the effective and user-friendly process to enter, store, handle, and update the information starting from a bibliography and ending in a data evaluation. Evaluation of data is performed using either two functions of temperature for data at 0.1MPa or at saturation or the Tait equation for density data at elevated pressures. The weighted least-squares method is employed to evaluate the adjustable parameters of smoothing functions. Search and export program modules allow various views, searches, and outputs of the content of the databases. At present, the database system contains about 4,400 records in the bibliographic part, more than 100,000 experimental data points for about 500 substances, and over 800 sets of parameters of smoothing functions for about 330 substances. The database system is intended as an effective tool for compilation and critical evaluation of data, not as a commercial databank for distribution.