On Maximal Frequent and Minimal Infrequent Sets in Binary Matrices

Given an m×n binary matrix A, a subset C of the columns is called t-frequent if there are at least t rows in A in which all entries belonging to C are non-zero. Let us denote by the number of maximal t-frequent sets of A, and let denote the number of those minimal column subsets of A which are not t-frequent (so called t-infrequent sets). We prove that the inequality (m–t+1) holds for any binary matrix A in which not all column subsets are t-frequent. This inequality is sharp, and allows for an incremental quasi-polynomial algorithm for generating all minimal t-infrequent sets. We also prove that the analogous generation problem for maximal t-frequent sets is NP-hard. Finally, we discuss the complexity of generating closed frequent sets and some other related problems.     

Haemorrhagic pericarditis and cardiac tamponade during chronic haemodialysis

The activities of glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate: NADP oxidoreductase, G6PD), 6 phosphate glucono dehydrogenase (6 phospho-D-gluconate: NADP oxidoreductase, 6PGD) lactate dehydrogenase (D-lactate: NAD oxidoreductase, LDH), glutamate oxaloacetate transaminase (L-aspartate: 2-oxo-glutarate aminotransferase, GOT) and hexokinase (ATP: D-hexo-6-phosphotrans-ferase, Hx) were measured over 24 h in isolated lymphocytes of normal subjects and in white cells of patients with chronic lymphatic leukaemia (CLL). The activitty patterns of all enzymes in the normal lymphocytes were similar. A computed pattern of all the results exhibited a circadian rhythm of activity with the highest level at 16.00 hours. The oscillations in the activities of the same enzymes in the CLL cells differed among the patients, although all the enzymes of the same individual showed a similar diurnal rhythmic pattern. All peaks in this group appeared between 20.00 and 08.00 hours. The possible importance of these observations in setting up therapeutic schedules was raised.     

Electrochemical investigation on prostaglandin F2α derivatives. I. Anodic iodination of prostaglandin F2α and its methylesther

Studies of the anodic iodination of prostaglandin F₂ were carried out under a variety of electrolytic conditions. The effect of anode material, potential, pH of the electrolyte, initial substrate concentration and charge passed were investigated. A preparative technique for the iodination, in an undivided cell, has been developed. The iodinated compound-in the form of its 6-endo-(H)isomer-can be obtained in a two-electron process, with 100% conversion and nearly a quantitative product and current yield, without by-products, when using a platinum anode and cathode, +1.5 V vs SCE potential and 30 vol% methanolic 1 M aqueous citrate buffer solution (pH 3.4–3.6) containing 1–2×10^–2 M of the substrate and KI as electrolyte. The method can be extended to other prostaglandin derivatives. On the basis of the experimental results a mechanism is proposed involving the iodine radical and the iodinated substrate radical as intermediates.     

Color characteristic of Castle District built on the hill

In this article the used of the colordynamic planning method is described and applied as an example to the façade of a building in Buda. The method of colordynamic planning consists of 3 essential parts. In the first part we decide on the limits of the color range to be used, based upon the requirements of the subject of planning. The decision on these limits is closely linked to the coordinates of the Coloroid system. In the second part the planner creates harmonic color scales from the previously selected color range. In this work he is helped by rules of the Coloroid system, based on harmony thresholds. In the third part the planner selects the color harmony combinations considered suitable by him. Following that, he finalizes the Coloroid coordinates of the proposed colors most suitable for the project. For the presentation of the colordynamic planning method, based on the Coloroid system, we use a real database of a colordynamic plan, which was awarded the first prize in an international competition.     

Valorization of waste polyethylene by blending with ethylene-vinylacetate and incorporating a new type of compatibilizer

Nowadays polyethylene is one of the polymers produced in the greatest volume and the amount of generated waste high-density polyethylene (w-HDPE) is significant as well. Valorization and recycling of w-HDPE can be realized by blending with different types of polymers and/or elastomers for example, ethylene-vinyl acetate (EVA). For the purpose of boosting of interfacial interactions between these two polymers experimental olefin-maleic-anhydride based additives have been incorporated into the blends after optimization of the processing temperature. Impact and tensile tests have been carried out in our research work besides microscopy measurements and investigation of the effects of additive structure by FT-IR and rheology. At higher processing temperature (220°C) both tensile properties and Charpy impact strength were increased, latter one improved by 245% measured at 5°C while elongation at break enhanced by 182% with incorporation of some experimental additives compared to the neat 70/30 w-HDPE/EVA. Changes in the hydrocarbon molecular chains of experimentally compatibilized blends were observed based on FT-IR results and rheological measurements. It can be concluded that one of the most basic notions of sustainability, the 4R's (reduce, recycle, reuse, recover) has been satisfied in a successful way.     

Lightweight porous silica foams with extreme-low dielectric permittivity and loss for future 6G wireless communication technologies

In the next generation wireless communication systems operating at near terahertz frequencies, dielectric substrates with the lowest possible permittivity and loss factor are becoming essential. In this work, highly porous (98.9% ± 0.1%) and lightweight silica foams (0.025 ± 0.005 g/cm3), that have extremely low relative permittivity (εr = 1.018 ± 0.003 at 300 GHz) and corresponding loss factor (tan δ< 3 × 10?4 at 300 GHz) are synthetized by a template-assisted sol-gel method. After dip-coating the slabs of foams with a thin film of cellulose nanofibers, sufficiently smooth surfaces are obtained, on which it is convenient to deposit electrically conductive planar thin films of metals important for applications in electronics and telecommunication devices. Here, micropatterns of Ag thin films are sputtered on the substrates through a shadow mask to demonstrate double split-ring resonator metamaterial structures as radio frequency filters operating in the sub-THz band.     

Factors influencing the scientific performance of Momentum grant holders: an evaluation of the first 117 research groups

Scientometrics - The Momentum program launched in 2009 provides funding of up to 1 million Euro to establish new, independent research groups at Hungarian academic institutions. Here, our aim was...     

GD‐OES and electrochemical study of Ce containing conversion layers of hot dip galvanised and by Sendzimir process continuously hot dip galvanised steel plates

The present work is focused on the conversion layers of hot dip galvanised and continuously hot dip galvanised steel sheets produced by ISD DUNAFERR, Co., Ltd. The conversion coatings on the galvanised steel plates were produced by dipping the plates into solutions of rare earth salts for different immersion periods. The applied rare earth salts were, cerium nitrate and cerium chloride, respectively. The corrosion resistance of the treated plates was tested by DC polarisation measurements and electrochemical impedance spectroscopic method (EIS). The most promising conversion layers were subjected to special corrosion test modelling the effect of the squeezing of plates or coils during storage and delivering and the humidity, simultaneously. The qualitative properties of the corroded surface were tested by glow discharge optical emission spectroscopy (GD‐OES).