Wyniki wyszukiwania - BazTech

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Kowalencyjne szkielety organiczne : otrzymywanie, właściwości, zastosowanie

Makowski Damian, Bajorowicz Beata

Wiadomości Chemiczne

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2024

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[Z] 78, 3-4

219--241

EN

Covalent organic frameworks (COFs) are a novel and unique crystalline porous organic polymers formed by the reversible condensation of building units containing light elements and linked by strong covalent bonds. Covalent organic frameworks consist of linkers (building units) and chemical bonds formed between two building units. By carefully selecting the appropriate linkers and bonds, it is possible to create covalent organic frameworks with distinct features. This work provides a concise overview of covalent organic frameworks, including their structural, surface, optical, and electronic properties. The preparation strategies most commonly employed for COFs are also presented, along with relevant examples. The potential applications of covalent frameworks in various fields such as: photocatalysis, medicine, gas separation and storage, photovoltaics and sensors are also discussed, highlighting the need for further development of this important class of materials.

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CaO-based high temperature CO2 sorbents – Literature review

Konopacka-Łyskawa Donata, Czaplicka Natalia, Szefer Andrzej

Chemical and Process Engineering

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2021

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Vol. 42, nr 4

411–-438

EN

The use of CaO-based adsorbents has a high potential to capture CO2 from various systems due to its high reactivity with CO2, high capacity, and low cost of naturally derived CaO. The application of CaO-based sorbents to remove carbon dioxide is based on a reversible reaction between CaO and CO2. However, multiple carbonation/calcination cycles lead to a rapid reduction in the sorption capacity of natural CaO, and therefore efforts are made to reduce this disadvantage by doping, regenerating, or producing synthetic CaO with stable sorption properties. In this review, the synthesis methods used to obtain CaO-based sorbents were collected, and the latest research on improving their sorption properties was presented. The most commonly used models to describe the CO2 sorption kinetics on CaO-based sorbents were also introduced. The methods of sorbent regeneration and their effectiveness were summarized. In the last part of this review, the current state of advancement of work on the larger scale, possible problems, and opportunities during scale-up of the calcium looping process were presented. Concluding (i) the presented methods of adsorbent synthesis allow for the production of doped CaO adsorbents on a laboratory scale, characterized by high CO2 capture efficiency and good cyclic stability, (ii) the most commonly used in practice models describing CO2 chemisorption are empirical models and the shrinking core model, (iii) the use of sorbent regeneration allows for a significant improvement in sorption capacity, (iv) the scale-up of both the production of new CaO adsorbents and the CO2 capture technology with their use requires further development.

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Aspects of nanomaterials for civil and military applications. Part 1. Origins, characteristics and fabrication methods

Foltynowicz Zenon, Czajka Bogdan, Maranda Andrzej, Wachowski Leszek

Materiały Wysokoenergetyczne

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2020

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T. 12(1)

5--16

EN

The study presents general aspects of highly dispersed nano scale materials including their origins, structure, classification, properties and production methods. In the last two decades, the unique properties and phenomena observed for those material has revolutionized the industry with a significant increase in research and the scope of practical applications of nanotechnology in every aspect of our lives.

PL

W pracy przedstawiono podstawowe aspekty materiałów o wysokim stopniu zdyspergowania w skali nanometrycznej obejmujące pochodzenie, budowę i klasyfikację, wykazywane właściwości oraz ich metody wytwarzania. Osobliwe właściwości i zjawiska wykazywane przez te materiały sprawiły, że w ostatnich dwóch dekadach jesteśmy świadkami rewolucji materiałowej. Świadczy o tym zarówno i istotny wzrost intensywności prowadzonych prac badawczych jak i rosnący zakres możliwości praktycznego stosowania osiągnięć nanotechnologii we wszystkich dziedzinach naszego życia.

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An Automatic Synthesis of Musical Phrases from Multi-Pitch Samples

Pluta M., Spalek L. J., Delekta R. J.

Archives of Acoustics

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2017

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Vol. 42, No. 2

235--247

EN

Sound synthesizers are a natural element of a musician’s toolset. In music arrangement, samplers can often produce satisfactory results, but it requires a combination of manual and automatic methods that may be arduous at times. Concatenative Sound Synthesis reproduces many of natural performance- and expression-related nuances but at a cost of high demand for processing power. Here, another method of musical phrase synthesis aimed at music arrangement is presented that addresses these and other related issues. Contrary to common practice, we propose to record and utilize sound samples containing not one, but short sequences of pitches. In effect, natural pitch transitions are preserved and phrases appear to be much smoother, despite using very limited set of performance rules. The proof-of-concept implementation of the proposed method is discussed in detail along with attempts at optimizing the final sound effects, based on auditory tests. The limitations and future applications of the synthesizer are also discussed.

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Synteza dyskretnych układów drgających metodą jednoznacznego rozkładu charakterystyki na ułamki proste i ułamki łańcuchowe

Buchacz A., Dymarek A.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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1999

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z. 52 [174]

259-264

EN

This paper presents the synthesis of mixed method of characteristic function calIed immobility. The method then is connection of two methods of synthesis: the method of distribution of characteristic into partial fraction and the continued fraction expansion method. The synthesis of discrete mechanical system has been presented.

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Poli(siarczek fenylenu). Cz. I. Otrzymywanie i właściwości

Hałasa E.

Polimery

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1999

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T. 44, nr 2

79-86

PL

Opracowanie literaturowe. Przedstawiono metody otrzymywania polifsiarczku fenylenu) (PPS). Z dostępnych danych można wnioskować, iż PPS na skalę przemysłową wytwarza się w wyniku homopolrkondensacji halogenotiofenolanów metali alkalicznych lub heteropolikmdensacji 4,4'-dibromobenzenu z bezwodnym siarczkiem sodu w środowisku polarnych rozpuszczalników organicznych. Omówiono procesy krystalizacji i rekrystalizacji PPS. PPS jest polimerem inżynieryjnym o znakomitej odporności termicznej (długotrwała praca w temperaturze do 240°C), ale drogim. Ogrzany do temperatury przekraczającej 300°C ulega cyklizacji, rozgałęzieniu i sieciowaniu; w tych warunkach mogą też tworzyć się liniowe struktury ąuasi-drabinkowe. Oprócz dobrej odporności termicznej, PPS charakteryzuje się znaczną odpornością na chemikalia i rozpuszczalniki, natomiast jest nieodporny na UV, W temp. < 175°C nie rozpuszcza się w żadnym rozpuszczalniku. Ze względu na ostre warunki kondensacji, korozję aparatury oraz toksyczność odgazów i ścieków produkcja PPS jest bardzo trudna.

EN

A review with 24 references covering the methods of preparation and crystallization and recrystallization of PPS. The available data allow to conclude that PPS has been commercially produced via homopolycondensation of alkali metal halophenolates or heteropolycondensation of 4,4'-di-bromobenzene with anhydrous sodium sulfide in polar organic solvents used as reaction media. PPS is an engineering polymer endowed with excellent thermal resistance (long-time operation at 240°C); however, PPS is expensive. When heated to temperatures exceeding 300°C/ PPS undergoes cyclization, branching and crosslinking processes to yield, occasionally, quasi-ladder linear structures. PPS is also well resistant to chemicals and solvents; but not to UV radiation. At temperatures lower than 175°C, PPS is insoluble in any solvent. The acute condensation conditions, corrosion of equipment, and the toxicity of waste waters and off-gases render production of PPS very difficult.