Wyniki wyszukiwania - BazTech

1

Czy jest możliwe zagospodarowanie osadów posodowych?

Dramiński M., Grzybowski P.

Przegląd Techniczny : Gazeta Inżynierska

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2016

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nr 11-12

17--19

PL

W artykule przedstawiono problem racjonalnego zagospodarowania osadów posodowych powstających przy produkcji sody w procesie Solvay’a. Przedstawiono przykłady zastosowania techniki e-beam do unieszkodliwiania różnych typów odpadów. Omówiono oczekiwania, jakie wiążą się z zastosowaniem wiązki elektronów energetycznych do procesu koagulacji i odsalania szlamów posodowych. Wskazano na komplikacje towarzyszące prowadzeniu badań w mało znanym obszarze innowacyjnych technologii e-beam.

EN

The problem of rational management of sludge from the production of soda in the Solvay process was presented. The examples of the use of e-beam technology for the disposal of various types of waste were described. The expectations connected with the use of electron beam energy to the process of coagulation and desalination of soda sludge were described. The complications associated with conducting of a research in an alien area of innovative e-beam technologies were pointed out.

2

Prolina : pospolity aminokwas wyjątkowy katalizator. Część IV, Reakcja Michaela

Karczmarska-Wódzka A., Studzińska R., Kołodziejska R., Wróblewski M., Dramiński M.

Wiadomości Chemiczne

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2014

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[Z] 68, 1-2

49--65

EN

In recent years there has been a dynamic development of asymmetric synthesis. Groups of researchers, particularly the one led by Benjamin List and Carlos Barbas, carried out a number of reactions and showed the effectiveness of the use of small organic molecules such as proline as catalysts. Michael addition catalyzed with proline is a particularly interesting reaction because it can be carried out in two aminocatalytic pathways. The analysis of Michael reaction reveals potential for both forms of aminocatalysis: enamine and iminium catalysis (Scheme 1) [1–14]. Presumably Michael reaction proceeds mainly according to enamine mechanism. The use of proline in Michael reaction with imine activated acceptor is slightly effective. So far the researches have shown that the modification of proline molecule or addition of other catalyst is necessary for condensation to appear. Enamine catalysis concerns the activation of carbonyl compound in situ being a donor. There is no need for enolase anion to be created earlier [2, 15–17]. When, as a result of the reaction of a,b-unsaturated carbonyl compound with proline, Michael acceptor activation appears it means that it is enamine mechanism reaction (Scheme 1) [2, 24]. One of the first examples of direct Michael reaction proceeding through enamine transition state is the reaction of cyclopentanone with nitrostyrene (Scheme 6) [20–23]. Other examples of Michael addition of ketone with nitro olefin catalysed by proline are shown in table 2 and 3 [10, 23, 30]. Nitroketones obtained in that way are useful as precursors for different organic compounds [33], also pyrrolidines [34]. Pyrrolidines are pharmacologically active and they selectively block presynaptic dopamine receptors [34] (Scheme 7). Except for Michael intermolecular reaction, intramolecular condensation adducts were also obtained. Michael intramolecular proline-catalyzed condensation in which inactive ketones transform into α,β-unsaturated carbonyl compounds was described (Scheme 9) [35, 36]. These reactions require a stoichiometric amount of a catalyst and a long time of reaction and they give as a result a little enantiomeric excess [11, 24, 35]. In 1991, Yamaguchi and co-workers carried out malonates Michael addition to α, β-unsaturated aldehydes catalyzed by L-proline [24, 39]. The reaction proceeded according to enamine mechanism, for example dimethyl malonate was reacted with hex- 2-enal in the presence of proline to give Michael adduct in 44% yield. To improve the yield an attempt of a slight modification of a proline molecule was made transforming it into proper salt. Proline lithium salt enabled to obtain the condensation product in 93% yield (Tab. 4). Regardless of a used catalyst the products in the form of racemates were obtained. In order to improve enantioselective properties of a catalyst, Michael addition of diisopropyl malonate to cycloheptenone was carried out in chloroform in the presence of different proline salts. Optimal enantioselectivity and yield was obtained by using rubidium salt (Tab. 5–7) [40, 41]. Rubidium prolinate-catalyzed Michael additions are used in industry e.g. for enantioselective synthesis of the selective serotonine reuptake inhibitior (SSRI) (–)-paroxetine (antidepressant) (Scheme 12) [24].

3

Prolina : pospolity aminokwas wyjątkowy katalizator. Część III, Reakcja Mannicha

Studzińska R., Karczmarska-Wódzka A., Wróblewski M., Kołodziejska R., Dramiński M.

Wiadomości Chemiczne

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2014

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[Z] 68, 1-2

21--48

EN

Mannich reaction occuring among ketone, aldehyde, and amine is one of the ways of a synthesis of biologically active compounds. Reactions of this type were carried out in the presence of different catalysts [3–10], however in recent years a lot of attention has been paid to enantioselective Mannich reaction catalyzed with proline. Such reactions were carried out with the use of different compounds containing carbonyl group and the most frequently used amine was p-anisidine. The advantage of the use of p-anisidine is a possibility of conducting the direct Mannich reaction (Scheme 3). In this way β-amino ketones (Tab. 1, 2, 4) [15, 18–20, 23, 24], α-hydroxy-β-amino ketones (Tab. 3) [15, 22], and β-amino alcohols (Tab. 5, 6) [25, 26] were obtained. A possibility of syntheses of β-amino sugars and α-amino acids with their derivatives (Tab. 7) [28, 29] is worth noticing. In a great number of described reactions, the products were obtained with satisfactory yield and enantiomeric excess. Taking into consideration the difficulty of a removal of p-hydroxyphenyl group which protects amine group in the resulting products, the attempts of using different amine compounds in Mannich reactions catalyzed with proline were undertaken. The use of amines blocked by tert-butoxycarbonyl group (Boc) enabled to obtain the products with high yield and ee values (Tab. 12–15) [35–38]. However in the case of the use of Boc the reaction must be carried out in an indirect way (it is necessary to prepare imine blocked by Boc earlier).

4

Reakcja Mitsunobu : mechanizm i zastosowanie

Kitkowska J. D., Tabaczyńska Ż. A., Dramiński M.

Wiadomości Chemiczne

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2013

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[Z] 67, 9-10

843--876

EN

The Mitsunobu reaction has been known since 1967, but the research on its modifications as well as on the introduction of new reagents, productivity, improvement and methods of post-reaction mixture separation is still being conducted. The original reaction was used to obtain esters by condensation of carboxylic acids and alcohols using triphenylphosphine and DEAD mixture. This reaction allows formation of s not only carbon-oxygen bond, but also carbon-carbon, carbon-nitrogen, and carbon-sulphur to be synthesized. The Mitsunobu reaction is widely applied in organic synthesis as a way of inversion of configuration of secondary alcohols or of aryl ethers synthesis. Numerous studies bring the accounts of using this reaction for the synthesis of steroids, carbohydrates, nucleosides, as well as alkaloids and other heterocyclic compounds containing nitrogen. The popularity of this reaction lies in its stereoselectivity and compatibility with a wide range of functional groups as well as in its moderate requirements considering reaction conditions. However, an isolation of a desirable product from the used up or surplus reagents still causes a lot of difficulties.

5

Prolina – pospolity aminokwas wyjątkowy katalizator. Część II, Międzycząsteczkowa kondensacja aldolowa

Kołodziejska R., Wróblewski M., Karczmarska-Wódzka A., Studzińska R., Dramiński M.

Wiadomości Chemiczne

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2013

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[Z] 67, 11-12

1027--1050

EN

Proline in organic synthesis is used as a small molecular organocatalyst. In a catalytic act proline, similarly to an enzyme, activates reagents, stabilizes transition state and influences an orientation of substrates [1–12]. Proline works as aldolase I (so called microaldolase I). In comparison with other amino acids it shows exceptional nucleophilicity which makes imines and enamines formation easier. In the intermolecular aldol reaction proline was used for the first time by List and co-workers (Scheme 1) [3, 9, 20]. Since then an immense progress has been observed in this field. Several aldolization reactions were performed in the presence of proline. Reactions of this type proceed between the donor (nucleophile) and the acceptor (electrophile). In aldol reaction the donors can be both ketones and aldehydes which next are condensed with ketones and aldehydes acting as electrophiles (Scheme 2–18; Tab. 1–7) [21–72]. The presence of proline ensures not only high yield of homo- and heteroaldolization but mainly enables conducting enantio- and diastereoselective synthesis. Intermolecular proline-catalyzed aldol condensation proceeds according to enamine mechanism. Anti-aldols, which make a valuable source of intermediates in the synthesis of important biologically active compounds, are mainly obtained in this reaction [35–44, 54, 58, 62, 63, 68, 69, 71].

6

Prolina – pospolity aminokwas wyjątkowy katalizator. Część I, Biosynteza proliny. Wewnątrzcząsteczkowa kondensacja aldolowa

Wróblewski M., Kołodziejska R., Studzińska R., Karczmarska-Wódzka A., Dramiński M.

Wiadomości Chemiczne

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2013

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[Z] 67, 9-10

801--818

EN

In asymmetric synthesis of organic compounds more effective solutions are being looked for which will result in higher yield(s) of product(s) and their high enantioselectivity [1]. One of such solutions is an use of a multilevel and cheap catalyst. Proline used as a catalyst is a substance of natural origin which was synthetically obtained by Willstätter who was carrying out research on hygric acid (Scheme 1) [10]. The cells of many organisms have a suitable enzymatic system essential for proline biosynthesis [15]. So far, three proline biosynthesis pathways have been described: from glutamate (Scheme 3 and 4), ornithine (Scheme 5 and 6), and arginine (Scheme 7) [16–28]. Proline which is obtained as a result of biosynthesis or supplementation is a substrate for many proteins. Characteristic and significant content (about 23%) of this amino acid was observed in collage. In cells proline can play an important role of osmoregulator [31–35] – a protective substance regulating the activity of such enzymes as catalase and peroxidase [36]. Proline as a secondary amine shows exceptional nucleophilicity facilitating imine and enamine formation. Used as a catalyst in aldol reaction makes with substrates like imine or enamine transition state imitating the activity of naturally occurring enzymes for this type of reaction, that is aldolases. In their research Hajos and Parrish, and Eder, Sauer and Wiechert used proline in intramolecular aldol reaction obtaining proper enones (Scheme 9) [60–62]. The process of intramolecular aldol reaction was used for a separation of racemic mixture of diketones (Scheme 10) [63, 64], cyclization of ortho-substituted aromatic aldehydes and ketones (Scheme 11) [65], synthesis of cyclic diketones (Scheme 13) [68] and domino reaction to obtain substituted cyclohexanones from beta-diketones and unsaturated ketones (Scheme 14) [69].

7

Enancjoselektywna enzymatyczna desymetryzacja katalizowana lipazami. Część 1, Związki prochiralne

Kołodziejska R., Karczmarska-Wódzka A., Tafelska-Kaczmarek A., Studzińska R., Dramiński M.

Wiadomości Chemiczne

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2013

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[Z] 67, 7-8

751--772

EN

In the enzymatic asymmetric synthesis, the enzyme allows the desymmetrization of achiral compounds resulting in chiral compounds of high optical purity. Therefore, this type of biotransformation is known as enantioselective enzymatic desymmetrization (EED) [1–11]. This method is related to the generation of an asymmetry (loss of symmetry elements) in prochiral molecules (most often an sp3 or sp2 hybridized carbon atom), in meso synthones, and centrosymmetric compounds. An achiral center of the tetrahedral system is defined as a prochiral one if it becomes chiral as a result of one of the two substituents replacement which, when separated from the particles, are indistinguishable (Scheme 1, 2) [1–4, 9, 12]. Asymmetric synthesis is enantioselective when one of the enantiotopic groups or faces of an optically inactive compound is biotransformed faster than the other (Scheme 3–5) [1, 10, 11, 13–15]. Lipases are enzymes of highest importance in stereoselective organic synthesis, mainly due to their exceptionally broad substrate tolerance, stability, activity in unphysiological systems, and relatively low price [9, 14]. The mechanism of enzymatic hydrolysis catalysed by hydrolases is similar to that observed in the chemical hydrolysis with the use of base. The selectivity of enzymatic catalysis depends on the substrate orientation in the enzyme active site (Scheme 6, 7) [25–29]. Lipases were successfully used for the desymmetrization of different prochiral diesters, alcohols and amines. Most lipases preferentially convert the same prochiral groups in the above mentioned types of reaction. This allows the preparation of the both enantiomers of the product in high chemical and optical yield (Scheme 9–13) [9, 13, 32–56].

8

Enancjoselektywna enzymatyczna desymetryzacja katalizowana lipazami. Część II, Optymalizacja warunków reakcji. Związki mezo

Karczmarska-Wódzka A., Kołodziejska R., Tafelska-Kaczmarek A., Przybyła T., Dramiński M.

Wiadomości Chemiczne

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2013

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[Z] 67, 9-10

819--841

EN

In the enzymatic asymmetric synthesis, the enzyme allows the desymmetrization of achiral compounds resulting in chiral compounds of high optical purity. Meso compounds (bearing a plane of symmetry) are very important group of compounds used in EEDs (Scheme 1) [1–4]. Similarly to prochiral compounds, selective acylation or hydrolysis of meso substrates leads to optically active products. Most lipases preferentially convert the same enantiomers in the above mentioned types of reaction. This allows the preparation of the both enantiomers of the product in high chemical and optical yield (Scheme 3–20) [35–58]. An effective enzymatic catalysis should be performed under conditions optimal for a biocatalyst performance. Hence, it is essential to select an appropriate reaction medium, the pH, and temperature [6–34]. Optimization of the reaction conditions in terms of an appropriate solvent selection is effective and most frequently the simplest way to modify the enzyme selectivity. One of the most important criteria for the solvent selection is its nature [25]. The enzyme selectivity is conditioned by its conformational rigidity, which increases in more hydrophobic medium (typical hydrophobic solvents, scCO2). A hydrophobic solvent decreases biocatalyst lability, which does not allow the connection between the structurally mismatched substrate and the active side of an enzyme [10, 26–31]. Ionic liquids are a separate group of solvents which, despite their high hydrophobicity (logP << 0) and polarity, can constitute an ideal medium for the biotransformation reactions [18–23].

9

Random Reducts : A Monte Carlo Rough Set-based Method for Feature Selection in Large Datasets

Kruczyk M., Baltzer N., Mieczkowski J., Dramiński M., Koronacki J., Komorowski J.

Fundamenta Informaticae

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2013

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Vol. 127, nr 1-4

273--288

EN

An important step prior to constructing a classifier for a very large data set is feature selection. With many problems it is possible to find a subset of attributes that have the same discriminative power as the full data set. There are many feature selection methods but in none of them are Rough Set models tied up with statistical argumentation. Moreover, known methods of feature selection usually discard shadowed features, i.e. those carrying the same or partially the same information as the selected features. In this study we present Random Reducts (RR) - a feature selection method which precedes classification per se. The method is based on the Monte Carlo Feature Selection (MCFS) layout and uses Rough Set Theory in the feature selection process. On synthetic data, we demonstrate that the method is able to select otherwise shadowed features of which the user should be made aware, and to find interactions in the data set.

10

The Monte Carlo feature selection and interdependency discovery is unbiased

Dramiński M., Kierczak M., Nowak-Brzezińska A., Koronecki J., Komorowski J.

Control and Cybernetics

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2011

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Vol. 40, no 2

199-211

EN

We show that the Monte Carlo feature selection algorithm for supervised classification proposed, by Dramiński et al. (2008), is not biased towards features with many categories (levels or values). While the algorithm, later extended to include the functionality of discovering interdependencies between features, is surprisingly simple and has been successfully used on many biological data and transactional data of commercial origin, and it has never revealed any bias of the type mentioned, the alleged property of its unbiasedness required a closer scrutiny which is thus provided here. Admittedly, the algorithm does reveal some bias coming from another source, but it is negligible. Hence our final claim is that the algorithm is practically unbiased and the results it provides can be considered fully reliable.

11

Accelerating PageRank computations

Wierzchoń S. T., Kłopotek M. A., Ciesielski K., Czerski D., Dramiński M.

Control and Cybernetics

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2011

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Vol. 40, no 2

259-274

EN

Different methods for computing PageRank vectors are analysed. Particularly, we note the opposite behavior of the power method and the Monte Carlo method. Further, a method of reducing the number of iterations of the power method is suggested.

12

Zastosowanie cieczy jonowych w enzymatycznej syntezie organicznej z wykorzystaniem katalitycznych właściwości lipazy B z candida antarctica

Kołodziejska R., Jasińska L., Karczmarska-Wódzka A., Dramiński M.

Wiadomości Chemiczne

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2010

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[Z] 64, 5-6

413-434

EN

In organic reactions chemical catalysts as well as catalytic proteins are used. Biocatalysts have become a useful tool for organic chemists, allowing selective, one-step syntheses. Lipases, hydrolytic enzymes, have gained a considerable attention [1]. Lipase-catalyzed reaction proceeds according to the "bi-bi ping-pong" (Scheme 1) [16]. Catalytic potential of lipases allows to obtain a wide range of organic compoundsby formation of C-C, C-N, and C-S bonds [6–8]. Enzyme-catalyzed reactions depend on change of basic-acidic properties or redox potential and an applicationof appropriate solvent can increase the control over chemical balance. The solvent used as the reaction medium should allow enzyme stability, increase its activity and selectivity. In organic hydrophobic solvents, enzyme is more stable and selective, its activity, however, is reduced in comparison to polar solvents [6–8]. During a search for optimal solvent special attention was paid to a typical organic solvents – ionic liquids. Ionic liquids are organic salts (Scheme 2) [9–13]. They do not mix with hydrophobic solvents such as hexane (Tab. 2) [9, 12, 13, 23] and their polarity is similar to low molecular weight alcohols (Tab. 3) [9, 12, 13, 22, 23, 32]. Because of their specific physical properties, ionic liquids may be optimal microenvironment for enzymes, influencing their activity and stability. CALB is widely used in organic syntheses because of its adaptive capability (Tab. 1) as well as regio- and enantioselective properties [18–21]. Due to its exceptional conformation stability in ionic liquids, CALB can be successfully applied both in heterogeneous (Tab. 4) [22, 36] and homogeneous catalysis (Scheme 4, Tab. 5) [37]. The activity of CALB after incubation in ionic liquids is comparable or greater than in conventional organic solvents (Tab. 6, Fig. 1) [9, 13, 23, 38]. A solvent used as a reaction medium should help to maintain enzyme stabilizing its active conformation and protecting it from deactivating factors such as temperature and scCO2 (Tab. 7) [38–43]. Some ionic liquids constitute a bridge between conventional organic solvents and physiological enzyme environment. They provide exceptional activity of catalytic proteins, which allows efficient and selective reaction catalysis (Tab. 8) [6,38–40, 43–61].

13

Semantic information within the BEATCA framework

Ciesielski K., Czerski D., Dramiński M., Kłopotek M. A., Wierzchoń B.

Control and Cybernetics

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2010

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Vol. 39, no 2

377-399

EN

In this paper we investigate the impact of semantic information on the quality of hierarchical, fuzzy-based clustering of a collection of textual documents. We show that via a relevant tagging of a part of the documents one can improve the quality of overall clustering, both of tagged and un-tagged documents.

14

Określanie konfiguracji absolutnej za pomocą magnetycznego rezonansu jądrowego

Kołodziejska R., Jasińska L., Karczmarska A., Dramiński M.

Wiadomości Chemiczne

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2008

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[Z] 62, 7-8

709-732

EN

In relation to a very limited scale of tolerance of organisms to different geometrical isomers it has been imperative to invent a method which would enable a precise and fast evaluation of a spatial structure of optically active compounds. Using a spectroscopic method of nuclear magnetic resonance (NMR) proved to be an excellent solution. In order to define an absolute configuration by means of NMR, the enantiomeric mixture must be transformed into diastereoisomeric one by adding chiral auxiliary substituents. We distinguish three types of chiral auxiliary reagents: CDAs (chiral derivatizing agents), CSAs (chiral solvating agents), CLSRs (chiral lanthanide shift reagents). Chiral derivatizing agents are the most frequently used in analyses. The condensation reaction of an auxiliary compound with enantiomer may be single or double derivatization. In case of a double derivatization, 1H NMR spectra of two diastereoisomers obtained as a result of condensation of (R)- and (S)-CDAs with the substrates are compared. The changes in the chemical shifts of the substituents L_1 (the most bulky substituent) and L_2 (the least bulky substituent) asymmetric carbon of the substrate in the two derivatives (R)- and (S)-CDAs is defined as ?[delta delta]^RS. The [delta]^RS value is the difference between the chemical shift in the (R)-CDAs derivative ([delta](R)) and (S)-CDAs derivative ([delta](S)) for the substituents L_1 ([delta delta]^RSL_1) and L_2 ([delta delta]^RSL2) (Figure 2). In case of a single derivatization, the tested enantiomer is combined with only one enantiomer ((R)- or (S)-CDA). In the single derivatization [delta delta]^AR ([delta delta]^AR = [delta](A)-[delta](R)) is the difference in the chemical shifts of the substituents L_1 and L_2 of a derivative and a free substrate (Figure 3) [1]. Among these auxiliary reagents are MPA (methoxyphenylacetic acid), MTPA (methoxytrifluoromethylphenylacetic acid), 9-AMA (9-anthrylmethoxyacetic acid), BPG (boc-phenylglycine), 9-AHA (ethyl 2-(9-anthryl)-2-hydroxyacetate), PGME (phenylglycine methyl ester), and PGDA (phenylglycine dimethyl amide). These reagents are currently being used to determine the absolute configuration of primary alcohols (Figure 4), secondary alcohols (Figure 5), tertiary alcohols, diols [2-5], triols [6], primary amines (Figure 6, 7), secondary amines (Figure 8), and carboxylic acids (Figure 9). Other methods of determining absolute configuration such as HPLC-NMR or "mix and shake" method are currently investigated - HPLC-NMR method allows determining the absolute configuration of enantiomeric mixture as well as a pure enantiomer, the use of semipreparative column allows to precisely distinguish the obtained derivatives, which undergo the spectroscopic analysis (Figure 11) [1]. The "mix and shake" method allows determining the absolute configuration in a few minutes and without any additional separation methods. The derivative/s is/are prepared by simply mixing a solid matrix-bond auxiliary reagent with a chiral substrate and NMR spectra of the resulting derivatives are obtained without any further manipulation (Figure 12) [7].

15

Map Quality Measurements for GNG and SOM based Document Collection Maps

Kłopotek M. A., Wierzchoń S. T., Ciesielski K., Dramiński M., Czerski D., Kujawiak M.

Studia Informatica : systems and information technology

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2006

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Vol. 1(7)

65--76

EN

The paper presents a proposal of a set of measures for comparison of maps of document collections as well as preliminary results concerning evaluation of their usefulness and expressive power.

16

Selective acetylation of pyrimidine nucleosides catalyzed by lipase goes smoothly in pyridine. Why?

Kołodziejska R., Dramiński M.

Polish Journal of Applied Chemistry

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2004

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Vol. 48, nr 3-4

75-81

EN

Enzymes are well known primarily as catalysts for carrying out regioselective reactions in organic syntheses. Results from enzyme - mediated protections of the hydroxy groups of pyrimidine 1-b-D-ribofuranosides and 1-b-D-2-deoxyribofuranosides have been discussed and the influence of solvent on efficiency of the syntheses has been tested. The lipase B from Candida antarctica selectivity transfers the acetyl group from vinyl acetate to the primary hydroxyl groups of various pyrimidine ribonucleosides nad 2'-deoxyribonucleosides in high yields. Conformation gauche-gauche is preferred in enzymatic acetylation, therefore the enzymatic transesteryfication is carried out faster in pyridine than in DMSO.

PL

W ciągu ostatnich lat wzrosło zainteresowanie specyficznymi właściwościami katalizatorów biologicznych. Na szczególna uwagę zasługuję enzymy lipolityczne. Lipaza jest szeroko stosowana do katalizowania reakcji hydrolizy i estryfikacji. Przeprowadzono reakcje tranestryfikacji ocatnem winylu wybranych nukleozydów i 2'-deoksynukleozydów pirymidynowych w obecnosci lipazy z Candida antarctica B. Stwierdzono, że lipaza z Candida antarctica B nie tylko umożliwia przeprowadzenie ze znaczną szybkością reakcji transestryfikacji ale przede wszystkim selektywnie wprowadza grupę acetylową na pierwszorzędową grupę wodorotlenową 1-b-D-rybofuranozydów i 1-b-D-2-deoksyrybofuranozydów pirymidynowych. Najlepsze rezultaty uzyskano prowadząc reakcję w pirydynie, prawdopodobnie substraty w tym rozpuszczalniku były bardziej dostępne dla katalizatora enzymatycznego i dlatego reakcja transestryfikacji enzymatycznej przebiegała znacznie szybciej w pirydynie niż w DMSO i DMF. Lipaza jest aktywna w każdym z użytych rozpuszczalników wobec innych substratów, przypuszczalnie korzystny przebieg naszych eksperymentów w pirydynie spowodowany jest konformacją nukleozydu określoną środowiskiem reakcji. Dla sprawdzenia tej tezy poddano analizie konformacyjnej wyjściowe nukleozydy i 2'-deoksynukleozydy pirymidynowych w stosowanych rozpuszczalnikach. Stwierdzono, że przewaga izomeru gauche-gauche (gg) sprzyja enzymatycznej reakcji transestryfikacji.

17

Elementy konstruktywnej indukcji w systemie INLENStar

Dramiński M.

Prace Instytutu Podstaw Informatyki Polskiej Akademii Nauk

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2001

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Nr 930

1-22

PL

Eksploracja wiedzy jest to szukanie relacji i ogólnych wzorców istniejących w dużych bazach danych. Ta praca daje pogląd na eksplorację wiedzy jako działu uczenia się maszyn ze szczególnym naciskiem na konstruktywną indukcję. Konstruktywna indukcja redukuje wrażliwość algorytmów indukcyjnych na ich słownik poprzez udostępnienie algorytmowi stworzenia nowych zmiennych. Konstruktywna indukcja umożliwia dużo szybszą drogę do przeszukiwania przestrzeni możliwych słowników. Praca prezentuje trzy algorytmy, które zostały zaimplementowane w aplikację INLENStar. Jeden z nich to nowy "Apriori*" zaprojektowany specjalnie na potrzeby INLENStar i dwa dobrze znane algorytmy "COBWEB" i "CLARA". Ogólnie wszystkie te algorytmy znajdują nowe zmienne używając grupowania na trzy różne sposoby. Praca zawiera dużą liczbę eksperymentów, w których zbadano właściwości wyżej wymienionych algorytmów.

EN

Data mining is the search for relationships and global patterns that exist in large databases. This paper provides overviev of database mining as the confluence of machine learning techniques and performance emphasis of constructive induction. Constructive induction reduces the sensivity of an inductive algorithm to its vocabulary by enabling the algorithm to construct new variables. Constructive induction is a much faster way to search the space of possible vocabularies. This work presents three algorithms implemented in INLENStar application. One of these algorithms is new "Apriori*" designed especially for INLENStar, and two well known algorithms "COBWEB" and "CLARA". Generally the three algorithms search for new variables using three different methods of clustering. The paper considers a large number of experiments, to study properties of the algorithms.