Wyniki wyszukiwania - Biblioteka Nauki

1

Status of exploited Baltic flounder stocks in the southern Baltic area (ICES SD 26)

100%

Draganik B. , Ivanow S. , Tomczak M. , Maksimov B. Y. , Psuty-Lipska I.

|

2007

|

tom Vol. 36, No.4

47-64

EN

Flounder is the target of directed fisheries in coastal waters and is a bycatch of cod fishing. Flounder were fished in the Baltic region ICES Subdivision 26 (SD 26) by Polish and Soviet fleets until 1991. Since that time political and economic changes have altered the exploitation structure of that area, leading to increased fishing effort and flounder catches. This report, which is based on Polish, Russian and Lithuanian data, presents a review of long term changes in flounder fisheries in SD 26, and describes the current status of flounder exploitation there. The extended Survival Analysis (XSA) method was used to assess the stock. The results indicate that the flounder stock in SD 26 is in good condition and that the spawning stock biomass (SSB) is at a consistently high level. However, the estimated mean fishing mortality (F^), with reference to Biological Reference Points, indicates that the stock is being exploited too intensely to be sustainable.

2

Reduction of NO using Mn(4+) and Fe(3+) - impregnated active carbon

88%

Grzybek T. , Buczek B.

|

1998

|

tom Vol. 72, nr 3

607-612

EN

Carbonaceous materials were promoted by consecutive impregnation with manganese salt (potassium permanganate with or without the addition of sulphuric acid) and iron salt. Texture of the materials obtained was studied by low temperature argon sorption and manganese and iron distribution by X-ray photoelectron spectroscopy. The influence of impregnating solution on the structure of the catalysts studied was discussed. Catalytic properties (activity and selectivity) in selective catalytic reduction of nitric oxide with ammonia of doubly promoted carbonaceous material were compared with iron or manganese-containing active carbon.

3

Identification of similar and orthogonal chromatographic thin-layer systems for two-dimensional separations of flavonoids and their analogues

88%

Daszykowski M. , Hawrył M. , Waksmundzka-Hajnos M. , Walczak B.

|

2008

|

tom Vol. 20, no. 3

283-307

EN

In this paper a broad overview of the retention behaviour of twenty flavonoids and their analogues in 74 TLC systems is reported. The compounds were chromatographed on different stationary phases (non-polar and polar-bonded stationary phases - wettable RP18W, silica, and aminopropyl-modified and diol-modified plates) developed with a variety of binary mobile phases (aqueous and non-aqueous). The chemometric techniques principal component analysis and hierarchical clustering were used to evaluate similarities and differences among the chromatographic systems. For selection of the most suitable systems either to perform two-dimensional separation or to enhance overall resolution by merging two stationary phases, indices scoring the separating power of a given system or pair of systems were applied. When separation of all pairs of chromatographic systems was evaluated with the index considered, the theoretical separation achieved in these systems could be visualized as a colour map. This colour map enabled rapid examination of resolution and selection of orthogonal systems enabling acceptable separation of the compounds. On the basis of the colour map it was found that relatively efficient two-dimensional separation of the compounds could be achieved on amino-modified plates developed using 9:1 tetrahydrofuran-water in the first dimension then 9:1, 4:1, 3:1, or 7:3 acetonitrile-water in the second dimension. Theoretically, the best separation could be achieved by combining diol-modified and amino-modified stationary phases and using 3:2 methanol-water and 9:1 acetonitrile-water, respectively, as mobile phases.

4

Three-factor market-timing models with Fama and French’s spread variables

88%

OLBRYŚ J.

Operations Research and Decisions

|

2010

|

tom 20

|

nr 2

91-106

EN

The traditional performance measurement literature has attempted to distinguish security selection, or stock-picking ability, from market-timing, or the ability to predict overall market returns. However, the literature finds that it is not easy to separate ability into such dichotomous categories. Some researchers have developed models that allow the decomposition of manager performance into market-timing and selectivity skills. The main goal of this paper is to present modified versions of classic market-timing models with Fama and French’s spread variables SMB and HML, in the case of Polish equity mutual funds.

5

Extractive separation of rare earth ions by using calix[4]arene with isopropyl hydrogen phosphonate at upper rim

88%

Ohto K. , Yamasaki T. , Inoue K.

Ars Separatoria Acta

|

2006

|

tom No. 4

96-106

EN

5,11,17,23-Tetrakis(isopropyl hydrogen phosphonomethyl)- 25,26,27,28 - tetrapropoxycalix[4]arene in cone conformation has been synthesized to investigate extraction behavior for nine trivalent rare earth metal ions from chloride media into chloroform, together with isopropyl hydrogen (4-propoxyphenyl)methylphosphonate as a corresponding monomer. Although the aqueous distributions of the present extractants were greater than those of butyl ester type of the previous extractants, they were trace and slight amounts under the experimental condition for calix[4]arene and monomeric derivatives, respectively. From the result of pH dependency, extraction takes place by a simple ion-exchange mechanism for both extractants. The extraction ability between the present extractants for rare earth ions was comparable. Results of a Job plot and a loading test indicate that for calix[4]arene derivative, stoichiometry of the extraction is 1:1. The separation efficiency of a calix[4]arene derivative is less than that of a monomeric derivative. It is attributed to the offset by the size effect of a coordination site at the larger upper rim of calix[4]arene (for relatively larger light rare earth ions) and strong affinity of phosphonate group to heavy rare earth ions. Such result is similar to that of derivatives with butyl ester.

6

Physico-Chemical Characteristic of Sulfated Mixed Oxides of Sn with Some Rare Earth Elements

88%

Jyothi T. , Sreekumar K. , Talawar M. , Mirajkar S. , Rao B. , Sugunan S.

|

2000

|

tom Vol. 74, nr 6

801-812

EN

A series of binary mixed oxides of tin with three rare earth elements viz. La, Ce and Sm were prepared by co-precipitation method and sulfate treatment was performed by treating the mixed hydroxides with sulfuric acid or ammonium sulfate. The physicochemical characterization has been done by XRD, BET-S.A., SEM, EDX, TG-DTA and IR spectroscopy. Adsorption of n-butylamine was used to probe the acidic properties of the catalysts. The strength and distribution of acid sites depend on the mixed metal oxide composition, as well as on the preparation method. The rare earth modified sulfated tin oxide catalysts are more active in the oxidative dehydrogenation of cyclohexanol and cyclohexane, compared to the corresponding mixed oxide systems and sulfated tin oxide. Among the different sulfated oxide systems investigated , cerium prooted catalysts displayed a better selectivity towards dehydrogenation products.

7

Characterization of the Methacrylate Copolymers with the Use of Inverse Gas Chromatography

88%

Maciejewska M. , Gawdzik B. , Grochowicz M.

|

2008

|

tom Vol. 82, nr 1-2

235-240

EN

Characterization of porous copolymers formed by suspension polymerization of methacrylate monomers with divinylbenzene is presented. Two representative copolymers were used as stationary phases in gas chromatography. In order to determine the influence of chemical structure of the monomers on their chemical nature the two procedures were used: the selectivity triangle and the general selectivity. As a reference phase PorapakQ – the least polar commercially available porous polymer was used. Porous structure of copolymers was also characterized using nitrogen adsorption isotherms.

8

Three – factor market-timing models with Fama and French’s spread variables

88%

Olbryś J.

|

2010

|

tom Vol. 20, No. 2

91-106

EN

The traditional performance measurement literature has attempted to distinguish security selection, or stock-picking ability, from market-timing, or the ability to predict overall market returns. However, the literature finds that it is not easy to separate ability into such dichotomous categories. Some researchers have developed models that allow the decomposition of manager performance into market-timing and selectivity skills. The main goal of this paper is to present modified versions of classic market-timing models with Fama and French’s spread variables SMB and HML, in the case of Polish equity mutual funds.

9

Effect of temperature on ethanol conversion over the surface of Zr-modified zeolite ZSM-5

75%

Ivanovna K. R. , Yurievich P. A.

Catalysis for Sustainable Energy

|

2014

|

tom 2

|

nr 1

EN

In this paper, we have shown modification of high-silicon zeolite ZSM-5 by zirconium, and the results of ethanol conversion on this catalyst. Effect of process parameters on the selectivity of ethanol dehydration products was analyzed. In addition, a mechanism of aromatic hydrocarbons formation including reactions of dehydrogenation, dehydrocyclization and alkylation of intermediates was discussed. It was found that with increasing temperature a selectivity decreased for reactions of isomerization and increased selectivity for aromatic products and products of cracking reactions. The data also confirms that hexene-1 is an intermediate in the conversion process of ethanol and the catalyst system with 1% Zr-ZSM-5 has a bi-functionality. Catalytic properties of the system in the conversion of hydrocarbons are determined by the presence on their surface of both Broensted and Lewis acid sites.

10

Glyphosate in agronomic performance and seed quality of soybean with cp4-EPSPs and cry1Ac genes

75%

Silva A. F. M. , Albrecht A. J. P. , Albrecht L. P. , Pellicci V. A. , Giovanelli B. F. , Ghirardello G. A. , Viana H. R. M. , Filho R. V.

|

11

Molecular dynamics simulations of potassium channels

75%

Domene C.

Open Chemistry

|

2007

|

tom 5

|

nr 3

635-671

EN

Despite the complexity of ion-channels, MD simulations based on realistic all-atom models have become a powerful technique for providing accurate descriptions of the structure and dynamics of these systems, complementing and reinforcing experimental work. Successful multidisciplinary collaborations, progress in the experimental determination of three-dimensional structures of membrane proteins together with new algorithms for molecular simulations and the increasing speed and availability of supercomputers, have made possible a considerable progress in this area of biophysics. This review aims at highlighting some of the work in the area of potassium channels and molecular dynamics simulations where numerous fundamental questions about the structure, function, folding and dynamics of these systems remain as yet unresolved challenges. [...]

12

Switchable multicomponent heterocyclizations for diversity oriented synthesis

75%

Chebanov V. A. , Desenko S. M.

Diversity Oriented Synthesis

|

2012

|

tom 1

|

nr 1

EN

The present comprehensive review1 contains the analysis of literature data concerning switchable multicomponent heterocyclizations and demonstrates the application of these types of reactions to solve the matters of Diversity Oriented Synthesis.

13

BADANIE INFORMACYJNEJ EFEKTYWNOŚCI RYNKU W FORMIE SILNEJ NA PRZYKŁADZIE WYBRANYCH FUNDUSZY INWESTYCYJNYCH

63%

Kompa K. , Grabska M.

Metody Ilościowe w Badaniach Ekonomicznych

|

2009

|

tom 10

|

nr 1

265-285

PL

Celem badań jest ocena efektywności 19 wybranych otwartych funduszy inwestycyjnych działających na polskim rynku. Analizy przeprowadzono dla danych dziennych z okresu od 2.11.2006r. do 2.11.2008r. Badaniem objęto szeregi 3-, 6-, 12- i 24-miesięczne. Do oceny efektywności wykorzystano wskaźniki Sharpe’a, Treynora i Jensena. Badano również selektywność i wyczucie rynku za pomocą metod Treynora-Mauzy’ego oraz Henrikssona-Mertona. Za indeks rynku przyjęto indeks WIG, a za instrumenty wolne od ryzyka - bony skarbowe.

EN

The aim of the research is evaluation of the efficiency of 19 selected open-end investment funds that have been operating at the Polish market. Analysis is based on daily data and covers the period from November, 2, 2006 to November, 2, 2008. Investigation is provided for the time series that contain observations from 3, 6, 12 and 24 months. The risk-free instruments are represented by selected treasury bonds and the market index is represented by the WIG (Warsaw Stock Exchange Index). In the research we apply Sharpe, Treynor and Jensen ratios as well as we investigate selectivity and market timing employing Treynor-Mauzy and Henriksson-Merton models.

14

Niepowodzenia w studiowaniu z perspektywy uczelni i studentów

63%

Smużewska M. , Wasielewski K. , Antonowicz D.

Edukacja

|

2015

|

nr 4(135)

130–146

PL

Przedmiotem rozważań podjętych w artykule jest zjawisko niepowodzeń edukacyjnych doświadczanych w trakcie studiów. Opisano, jak niepowodzenia są postrzegane przez przedstawicieli szkolnictwa wyższego, oraz jakie działania podejmuje się, aby im zaradzić. W pierwszej części artykułu przybliżono historię badań nad zjawiskiem niepowodzeń edukacyjnych oraz przeanalizowano narosłe w wyniku odmiennych tradycji metodologicznych problemy koncepcyjne i nieścisłości terminologiczne, które utrudniają prowadzenie analiz w tym obszarze. W drugiej części przedstawiono wyniki badań empirycznych, przeprowadzonych w formie 15 indywidualnych (z ekspertami w zakresie polityki publicznej wobec szkolnictwa wyższego) oraz 2 wywiadów grupowych (z młodymi pracownikami nauki i studentami). Badanie przeprowadzono w dwóch szkołach wyższych: publicznym uniwersytecie i uczelni niepublicznej o charakterze zawodowym. Skupiono się w nim na kwestii niepowodzeń edukacyjnych jako wyzwaniu dla polityki publicznej oraz polityki rekrutacyjnej realizowanej przez szkoły wyższe. W trzeciej części omówiono działania podejmowane przez badane uczelnie w celu minimalizacji skutków niepowodzeń edukacyjnych. Z wyników przeprowadzonego badania wynika, że zarówno na poziomie centralnym, jak i instytucji szkolnictwa wyższego, przerywanie nauki nie jest traktowane jako problem. Więcej uwagi poświęca się niewystarczającej selekcyjności systemu, problemom z rekrutacją czy kryzysowi demograficznemu jako zagrożeniu dla etatów nauczycieli akademickich.

EN

The paper aims to address drop-out from Polish higher education, focusing on two fundamental issues: (a) how it has been seen by various internal stakeholders; (b) what kind of action (if any) has been taken to address the problem by institutions themselves. The paper is in three major parts. The first examines the history of empirical studies and includes a major theoretical discussion about forms of educational failure in Poland. The intentionwas to raise all the major problems related to overlap in terminology reflecting the wide range of disciplines, in which drop-out has been researched. The second and the third parts report the empirical research, namely individual (IDI) and focus group interviews (FDI). In the second section special attention is paid to educational failure, while in the third the focus is on the various strategies to reduce its impact used by two institutions in public and private higher education.

15

Enhancing the selectivity of amperometric nitric oxide sensor over ammonia and nitrite by modifying gas-permeable membrane with Teflon AF ®

63%

Cha W. , Meyerhoff M. E.

|

2006

|

tom Vol. 51, No. 6

949-961

EN

A planar amperonietric nitric oxide (NO ) sensor based on a platinized platinum (pPt) working electrode (as anode) is one of the most sensitive NO detection methods reported to date with sub-nmol L-1 detection limits. The use of an outer gas permeable membrane (porous polytetrafluoroethylene (PTFE) membrane) in this sensor design has been shown to impart superior NO selectivity over common interfering species present in biological samples, such as nitrite and ascorbate. Recently, however, it has been recognized that ammonia (NH3(g) present in biological samples, e.g., cell culture medium or blood, can interfere with NO detection using this sensor configuration owing to the concomitant oxidation capability of ammonia at the surface of the inner platinized platinum electrode. Herein, the selectivity of such an amperometric NO sensor is investigated in detail over both ammonia and nitrite and these results are compared to experimental data obtained with other types of ampcrometric NO sensors (including commercial WPI, Inc. device). Further, it is demonstrated that the NO selectivity of the planar-type NO sensor can be enhanced significantly by treating the porous PTFE gas permeable outer membrane with a Teflon AF<® solution. By filling the pores of the outer membrane with Teflon AF®, the flux of ammonia and nitrite to the internal working electrode is greatly reduced, while maintaining good permeability toward NO(g).

PL

Oznaczanie tlenku azotu (NO3 (g)) przy użyciu planarnego amperometrycznego sensora wykorzystującego elektrodę pracującą 7 platynowanej platyny jest jedną z najczulszych metod oznaczania tego analilu. z granicą detekcji poniżej nanomola, opracowanych do tej pory. Zastosowanie membrany przepuszczalnej dla gazów (membrana z porowatego poli(telrafiuo-roetylenu) (PTFE)) do konstrukcji tego sensora, pozwoliło uzyskać wysoką selektywność na tlenek azotu, jednocześnie dyskryminując często obecne w próbkach biologicznych interferenty, takie jak: azotany(III) i askorbiniany. Jednakże ostatnio dowiedziono, że amoniak (NH3(g) ) obecny w próbkach biologicznych, np. roztworze do hodowli komórek czy krwi,może zakłócać oznaczanie NO przy tej konfiguracji sensora, w związku z równoległym utlenianiem amoniaku na powierzchni wewnętrznej elektrody z platynowanej platyny. W pracy przedstawiono badania nad selektywnością amperometrycznego sensora NO w obecności zarówno amoniaku, jaki i azotanów(III). Wyniki te zostały porównane z wynikami otrzymanymi d!a innych typów amperomctrycznych sensorów NO (miedzy innymi handlowo dostępnego urządzenia WP1, Inc.). Ponadto pokazano, że selektywność planarnego sensora NO może być znacznie poprawiona poprzez poddanie działaniu roztworem teflonu AFAF®: zewnętrznej membrany wykonanej z porowatego PTFE. Po wypełnieniu porów membrany Teflonem AFAF®, przepływ amoniaku i azotanów (III) do elektrody pracującej został znacznie zredukowany, podczas gdy przepuszczalność dla NO pozostała na dobrym poziomie.

16

Badanie selektywności przebiegu reakcji równoległych w reaktorze zbiornikowym z mieszadłem : efekty mieszania i sposobu zasilania reaktora

63%

Bałdyga J. , Makowski Ł.

|

2002

|

tom Nr 4

29-30

PL

Przedmiotem pracy jest badanie wpływu mieszania burzliwego na przebieg homogenicznych, równoległych reakcji chemicznych przebiegających w reaktorze zbiornikowym z mieszadłem o działaniu ciągłym i półokresowym. Zbadano wpływ szybkości i miejsca zasilania oraz częstości obrotów mieszadła na selektyw- ność przebiegu reakcji. Przeprowadzono badania doświadczalne oraz obliczenia przy użyciu CFD.

EN

The paper is focused on effects of turbulent mixing on the course of parallel homogeneous chemical reactions carried out in a continuous-flow and semi-batch stirred tank reactors. Effects of feeding rate, feeding point position and stirrer speed are investigated. Experimental investigations as well as CFD computations are carried out.

17

Influence of feed quality on quality of separation products evaluated by means of the fuerstenau plot for symmetrical separation curves

63%

Duchnowska M. , Drzymała J. , Duchnowska M. , Drzymała J.

|

nr 2

18

Micromixing effects in precipitation - Application of CFD

63%

Bałdyga J. , Orciuch W. , Makowski Ł.

|

2006

|

tom Vol. 8, nr 1

4-11

EN

The process of precipitation of solid products from two liquid ionic solutions is interpreted theoretically and simulated using PDF closure procedure developed earlier by the authors. The process is described using statistically averaged balance equations including species balances for the reactants and the population balance for particles. The method enables the particle size to be predicted and compared with the experimental data. The criteria for either including or neglecting micromixing effects in modeling are presented and discussed.

19

Gold(I) recovery by functionalized vinylbenzyl chloride-divinylbenzene copolymer gels bearing amino ligands

63%

Pilśniak-Rabiega M.

|

2011

|

tom Vol. 55, nr 3-4

133-140

EN

The functional resins with amino ligands were synthesized by the modification of vinylbenzyl chloride- divinylbenzene copolymers gels (VBC/DVB) with the aliphatic and aromatic amines. Two methods of modification were employed, the first one was traditional heating of the polymer with either neat amine or amine solution in an appropriate solvent, the second method was heating of reaction mixture in a microwave reactor. These polymeric materials were characterized using nitrogen and chlorine elemental analysis. The polymeric resins were used for the removal of gold from ammonium buffer that contains 100 g/L NHrH20 and 50.0 g/L (NIL^SO.!. All resins were highly selective for the gold(I) from ammonia solution and they did not sorb ammine complexes of copper(II).

20

Stimuli responsive membranes for cations separation

63%

Smolińska-Kempisty K. , Bryjak M.

|

2011

|

tom Vol. 55, nr 2

65-71

EN

Poly(N-isopropylacrylamide), PNIPAM, and copolymers of N-isopropylacrylamide and di(ethylene glycol)methyl etber methacrylate, P(NIPAM-co-DEGMEM), grafted on the polypropylene membranes exhibited excellent conformational responses to temperature changes. Membranes were impermeable for aqueous solution at room temperature while at 43 °C the flux reached 0.048-0.061 cm3/cm2min at 0.02 MPa. Permeation of LiCl and NaCl was tested in dialytical process. The best results for LiCl and NaCl fluxes were obtained at room temperature. Probably, at this temperature DEGMEM units facilitated the ions transport. It is expected that ethylene glycol units created structure of channels for lithium and sodium ions.