Wyniki wyszukiwania - Biblioteka Nauki

1

Pomiar prądu elektryzacji przy użyciu precesji Larmora.

100%

Bednarska V. , Zmarzły D. , Aksamit P.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

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2006

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tom Vol. 44, nr 18

213-216

PL

Artykuł zawiera krótkie omówienie fizycznych podstaw zjawiska jądrowego rezonansu magnetycznego. Możliwość nieinwazyjnego badania np. prądu elektryzacji przy obserwacji tego zjawiska oraz fakt, iż jest ono wykorzystywane w szerokim spektrum zastosowań (również w medycynie) dało impuls do podjęcia próby użycia obserwacji precesji Larmora do zastosowań technicznych. Przedstawiono sposoby pomiaru prądu elektryzacji przy użyciu układów w trzech konfiguracjach: konfiguracji jedno- i dwu- solenoidalnej oraz w wersji z cewką toroidalną.

EN

The paper contains short presentation of the physical backgrounds nuclear spin magnetic resonance. The opportunity of non-destructive examination of the exclusive parameters e.g. current of electrisation with observation this phenomena and the fact that it is already applied with the great spectrum of techniques (also in medicine). Those were reasons to try to find the way of use Larmor precession observations for specific technical applications. Some configurations of measurement setup are also presented in this paper.

2

Conformational analysis of fragment of human Pin1 ww domain: influence of charged amino-acid residues on β-hairpin structure

86%

Makowska J. , Uber D. , Żmudzińska W. , Chmurzyński L.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2014

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tom Vol. 18, No 4

343--349

EN

We examined the effect of like-charged residues on the conformation of an original nine amino-acid-residue fragment of the human Pin1 WW domain (hPin1) with the f ollowing sequence: Ac-Arg-Met-Ser-Arg-Ser-Ser-Gly-Arg-Val-NH 2 (U9). This was facilitated by CD and NMR spectroscopic measurements, and molecular dynamics calculations. Our ear lier studies suggested that the presence of like-charged residues at the end of a shor t polypeptide chain composed of nonpolar residues could induce a chain reversal. For the U9 pep tide, canonical MD simulations with NMR -derived restraints demonstrated the presence of ensembles of stru ctures with a tendency to form a β -chain reversal. Additionally, thermal stabilities of the peptide und er study were measured using differential scanning calorimetry ( DSC ). The estimated well defined phase transition point showed that conformational equilibria in the U9 pe ptide were strongly dependent on temperature.

3

Laboratorium hiperpolaryzowanych środków cieniujących NMR : tomografia MR hiperpolaryzowanych środków cieniujących

86%

Obrębski W. , Piątkowska-Janko E. , Sawionek B. , Orzeł J. , Kossowski B. , Werys K. , Szczepankowski M. , Tor P. , Bogorodzki P.

Elektronika : konstrukcje, technologie, zastosowania

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2015

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tom Vol. 56, nr 7

7-11

PL

Artykuł przedstawia laboratorium technik rezonansu magnetycznego (NMR) w którym prowadzone są badania magnetyzacji układów spinowych, w szczególności badania mechanizmów indukowania i utrzymywania wysokich stopni polaryzacji spinowej zwanej hiperpolaryzacją i dotyczy próbek stałych (13C, 29Si) czy gazowych (3He, 129Xe), która pozwala na wzmocnienie ich sygnału jądrowego rezonansu magnetycznego o cztery rzędy wielkości.

EN

This paper presents a magnetic resonance laboratory (NMR) where magnetization of spin systems is studied, in particular development of robust strategies for inducing and maintaining a high nuclear spin polarization levels called hyperpolarization either solid (13C, 29Si) or gaseous (3He, 129Xe)samples. Sample hyperpolarization gains its nuclear magnetic resonance signal in four orders of magnitude giving enormous sensitivity enhancement in NMR and MRI.

4

Badanie dynamiki układów za pomocą spektroskopii NMR

86%

Jankowski S.

Wiadomości Chemiczne

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2005

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tom [Z] 59, 1-2

93--106

EN

The dynamic NMR (DNMR) deals with different techniques for rate constant determination for different chemical processes. The complete band shape analysis is applicable to the study of processes occurring with rate constants between 1 and 104 s-1. The measurements of relaxation times are useful for faster processes with rate constants of the order of 102-106 s-1 and the spin-saturation technique can be applied for slower processes (k = 0,1-100 s-1. Kinetic measurements by EXSY experiment are applicable for rate constants between 10-2 and 102 s-1. The advantages and pitfalls of every method were discussed.

5

Application of surfactant-modified montmorillonite in nitrophenol removal by adsorption

86%

Baysal G.

Environment Protection Engineering

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2019

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tom Vol. 45, nr 2

19--33

EN

Quaternary ammonium salts (QASs) such as 1-methyl-di-nonyl-1 phenyl ammonium iodide (QAS1) and 1-methyl-di-dodecyl-1 phenyl ammonium iodide (QAS2) were newly synthesized by complete alkylation reaction for modification of sodium montmorillonite (Mt). The sodium montmorillonite was modified via an ion-exchange reaction with QAS1 and QAS2, and two organoclays, Mt1 and Mt2, have been obtained. The synthesized quaternary ammonium salts were analyzed by nuclear magnetic resonance spectroscopy (NMR). The organoclays (Mt1 and Mt2) were characterized by a range of methods including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The adsorption capacities of the synthesized organo-montmorillonites for the hydrophobic organic pollutant 4-nitrophenol (4-NP) have been evaluated. The distances between the organoclay layers showed a much better opening than that reported in the literature. The results show that the adsorption capacity increased in the order Mt2 > Mt1. The adsorption capacities of Mt1 and Mt2 for 4-NP were 77% and 81%, respectively.

6

Badanie mobilności wody w jabłkach odwadnianych osmotycznie metodą magnetycznego rezonansu jądrowego (NMR)®

86%

Samborska K. , Kowalska H. , Tylewicz U. , Dalla Rossa M.

Postępy Techniki Przetwórstwa Spożywczego

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2017

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tom Nr 2

20--26

PL

Celem prac przedstawionych w artykule jest analiza wpływu odwadniania osmotycznego (OD) na wymianę masy w jabłkach. W celu określenia zmian w strukturze oraz żywotności komórek użyto jądrowego rezonansu magnetycznego (NMR) oraz mikroskopu fluorescencyjnego. Odwadnianie osmotyczne prowadzono w roztworach sacharozy oraz mieszaninach sacharozy i soków owocowych o ekstrakcie 22 i 65°Brix w temperaturze 45°C. Analiza NMR może być wykorzystywana do określenia obecności i miejsca występowania wody w komórkach tkanki poddanej odwadnianiu osmotycznemu. Informacje te mogą być przydatne w ocenie zmian destrukcji tkanki i zaburzenia jej integralności, a od strony technologicznej do kontroli wymiany masy zachodzącej podczas odwadniania osmotycznego.

EN

The aim of this work presented in the paper is to analysis of the influence of osmotic dehydration (OD) on mass transfer in apples. Fluorescence microscopy and time domain nuclear magnetic resonance (NMR) were respectively used to evaluate cell viability and microstructural changes during osmotic dehydration. The OD of apple was carried out in 22 and 65°Brix sucrose solutions or mixture of sucrose solution and fruit juices at 45°C, for a contact period from 0 to 1440 min. NMR analysis can be used to determine the presence and water state in the dehydrated cells. This information may be useful in assessing changes in tissue destruction and its integrity, and on the technological side to control the mass exchange occurring OD.

7

Analysis of rock pore space saturation distribution with Nuclear Magnetic Resonance (NMR) method. Part II

86%

Zalewska J. , Cebulski D.

Nafta-Gaz

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2011

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tom R. 67, nr 9

619-626

EN

The study presents results of laboratory examinations carried out on drill cores originating from various facies of Upper Rotliegend from a region to the North and North-West of Poznań, aimed at evaluation of their pore space saturation. The results were obtained on the basis of data acquired with Nuclear Magnetic Resonance (NMR) method. It has been found that samples of Aeolian dune sandstones representing A2 facies featured the best parameters, while the worst ones characterized samples originating from P2 sandy playa and P1 marginal playa facies. Comparison of results obtained for A2 facies formations in examined boreholes made it possible to find out that samples from O-3 borehole featured the best reservoir properties.

PL

W pracy przedstawiono wyniki badań laboratoryjnych przeprowadzonych na rdzeniach wiertniczych pochodzących z różnych facji utworów górnego czerwonego spągowca z rejonu na północ i północny-zachód od Poznania, w celu oceny nasycenia ich przestrzeni porowej. Wyniki otrzymano na podstawie danych uzyskanych metodą jądrowego rezonansu magnetycznego (NMR). Stwierdzono, że najlepszymi parametrami charakteryzowały się próbki piaskowców eolicznych wydmowych, reprezentujące fację A2, a najgorszymi - próbki pochodzące z facji plaji piaszczystej P2 i plaji brzeżnej P1. Porównując wyniki otrzymane dla utworów facji A2 w badanych otworach wiertniczych stwierdzono, że najlepsze własności zbiornikowe skał posiadają próbki z otworu O-3.

8

Preparation, Separation and Identification of Some para-Substituted ONN and NNO trans-Azoxybenzenes

81%

Domański A. A. , Kyzioł J. B.

Polish Journal of Chemistry

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2001

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tom Vol. 75, nr 12

1839-1846

EN

A series of para-substituted azoxybenzenes was obtained as model compounds for the investigation on the mechanism of Wallach rearrangement. Oxidation of azobenzenes with hydrogen peroxide in acetic acid solution, provided mixtures of alfa and beta isomers. Some couples of the products were separated, using chromatography and crystallization techniques, and identifiedon the basis of their carbon NMR and mass spectra. The SCSDal-gorithm can be applied to the interpretation of the I3C-NMR spectra. Recognition of the ipso andpara carbons suffice to the identification of an isomer, hence there are no strong interactions between the azoxy group and another substituent across the aromatic ring. Fragmentation of azoxybenzenes under electron impact occurs preferentially on the oxidized side of the azoxy bridge. Relative intensities of daughter ions differentiate the ONN = a. and NNO = P isomers in most cases.

9

Nuclear magnetic resonance spectroscopic studies of the trihexyl (tetradecyl) phosphonium chloride ionic liquid mixtures with water

81%

Dwan J. , Durant D. , Ghandi K.

Open Chemistry

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2008

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tom 6

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nr 3

347-358

EN

Tetra-alkyl Phosphonium ionic liquids are phosphonium salts with melting points near room temperature. We report the NMR studies of water-trihexyl (tetradecyl) phosphonium chloride ionic liquid mixtures. The proton chemical shifts were used to investigate the intermolecular interactions in mixtures of ionic liquids and water. The OH chemical shifts were found to decrease as the water concentration in the ionic liquid increased, and their rate of change with temperature decreased with water concentration. The CH2 and CH3 chemical shifts were found to move downfield with the increase in temperature, and moved further downfield as water concentration was decreased. The interface of experimental data and the results of quantum calculations suggest a significant binding of phosphonium cations to chloride anion and water molecules. As well, the analysis of the data suggests a possible transformation from cationchloride-water configuration at low water concentrations to cation-water-water at higher water concentrations. [...]

10

1H NMR, 13C NMR and Computational DFT Study of the Structure of 2-Acylcycloalkane-1,3-diones in Solution

81%

Szczeciński P. , Gryff-Keller A. , Molchanov S.

Polish Journal of Chemistry

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2007

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tom Vol. 81, nr 8

1449-1455

EN

1H and13C NMR spectra of 2-acylcyclopentane-1,3-dione [acyl = formyl (1); acetyl (2)] and 2,6-dioxocyclohexanecarboxylic acid (3) have beenmeasured. The optimummolecular structures of endo- and exo-enolic forms of investigated objects in solution have been found using DFT method with B3LYP functional and 6-311G(2d,p) basis set. The theoretical values of the NMR parameters have been then calculated using GIAO-DFT method with the same functional and basis set. The theoretical data obtained for compounds 1–3 have been used to interpret their experimental NMR spectra in terms of the equilibrium between different tautomers. It has been found that for investigated triketones an endo-tautomer overwhelmingly prevails.

11

Application of Spatially resolved NMR Spectroscopy for High resolution Spectra of Heterogeneous Samples

81%

Koźmiński W.

Polish Journal of Chemistry

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2000

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tom Vol. 74, nr 8

1185-1189

12

A Comparison of Solution Conformations of Scyliorhinin I and Its Analogue with N-Methyl-L-phenylalanine in Position 7

81%

Klaudel L. , Rodziewicz-Motowidło S. , Liwo A. , Rolka K.

Polish Journal of Chemistry

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2000

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tom Vol. 74, nr 8

1091-1099

EN

Their solution structures are characterized by families consisting of 7 and 8 conformers, respectively, with statistical weights higher than 2%. The 3D structure of Scyl is rather flexible, whereas the presence of a local constrait in position 7 significantly rigidifies the whole molecule.

13

1:3 Complex between beta-Cyclodextrin and Dendrimer with Three Branches Involving Four Glycine and One Adamantyl Group

81%

Dodziuk H. , Demchuk O. , Koźmiński W. , Dolgonos G.

Polish Journal of Chemistry

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2003

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tom Vol. 77 / nr 3

333-340

EN

The first-generation dendrimer, benzene-sym-tris-N,N,N-carbonyltriglycylglycine N_-1-adamantylamide, was synthesized by a modification of a described procedure. Its complexation with alfa-, beta- and gamma-cyclodextrins was studied by NMR. The complexation induced fit and NOESY studies indicate that, in agreement with molecular mechanics calculations, the complex with alfa-cyclodextrin is considerably stronger than those with beta- and gamma-cyclodextrins.

14

Structure of the Polysaccharide O-Antigen of Salmonella Aberdeen (O : 11)

81%

Szafranek J. , Kaczyńska M. , Kaczyński Z. , Gajdus J. , Czerwicka M. , Dziadziuszko H. , Głośnicka R.

Polish Journal of Chemistry

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2003

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tom Vol. 77 / nr 9

1135-1140

EN

O-specific polysaccharide (OPS) of Salmonella Aberdeen was obtained from bacterial cell mass by water-phenol extraction procedure of lipopolysaccharide (LPS) followed by its mild acid hydrolysis and gel filtration of soluble carbohydrate material. Rhamnose, galactose, N-acetyl-glucosamine and mannose were detected and their linkages were established. Sugar configurations, D or L, were determined for (S)-(+)-2-butyl glycosides on an achiral capillary column. The structure of OPS was determined by analysis of spectra of 1H and 13C NMR and homonuclear and heteronuclear correlations spectra. Anomeric configurations were tentatively assigned by chromium trioxide oxidation and later proved by anomeric proton chemical shifts, H1-H2 coupling constants and proton coupled 13C spectra. Sugar sequences were established from comparisons of specific carbon shifts with those from literature, two-dimensional nuclear Overhauser effect spectroscopy (NOESY) and heteronuclear multiple-bond correlation experiments (HMBC). The repeating unit of S. Aberdeen OPS has the structure: _3)-_-D-GlcpNAc-(1_3)-[ _-D-Manp-(1_4)-]_-D-Galp-(1_4)-_-L-Rhap-(1_

15

1H NMR, 13C NMR and Computational Study of the Structure of Salicylaldehyde Anion in Solution

81%

Horbaczewski M. , Szczeciński P. , Gryff-Keller A. , Molchanov S.

Polish Journal of Chemistry

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2007

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tom Vol. 81, nr 12

2089-2096

EN

1H NMR and 13C NMR spectra of salicylaldehyde potassium salt in DMF-d7 solution with addition of kryptofix 222 were mea sured. Quantitative comparison of car bon chemical shifts with shielding constants calculated for syn and anti con form ers of salicyl aldehyde an ion [GIAO DFT B3LYP/6-311G(2d,p) PCM] re vealed that in the applied conditions the anti form prevailed. Similar correla tion performed for salicylaldehyde lith ium salt indicated that in this case the syn conformer dominated. Analysis of experimental and calculated J(1H,13C) and J(1H,1H) values supported above conclusions.

16

Preparatyka 13C- i 15N- znakowanych RNA do badan strukturalnych metodami heterojadrowego, wielokierunkowego magnetycznego rezonansu jadrowego [NMR].

81%

Olejniczak M.

Biotechnologia

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1996

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nr 1

176-182

17

New serinolic amino-s-triazines by chemoselective amination of cyanuric chloride and their (pro)diastereomerism in restricted rotational phenomena

81%

Moldovan O. , Lameiras P. , Henon E. , Popa F. , Martinez A. , Harakat D. , Sacalis C. , Ramondenc Y. , Darabantu M.

Open Chemistry

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2012

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tom 10

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nr 4

1119-1136

EN

The highly chemoselective preparation of new elaborated N-unsymmetrically substituted chlorodiamino-s-triazines and melamines, seen as building-blocks for iterative synthesis, is reported. It consisted of amination of cyanuric chloride with commercial C-2-substituted 2-aminopropane-1,3-diols (“serinols”), playing the role as “open-chain” unit and enantiopure (1S,2S)-2-amino-1-(4-nitrophenyl)propane-1,3-diols (“p-nitrophenylserinols”) based amino-1,3-dioxanes (“closed-chain” unit). Issued from the restricted rotation about C(s-triazine)-N(exocyclic) partial double bonds, seen as axes of (pro)diastereomerism, a global four-component rotational equilibrium involving the title compounds is discussed based on DFT computation and (VT) NMR data. Depending on π-deficiency of the s-triazine core, an (un)synchronised deblocking of the generated rotational diastereomers was observed. They are discussed as influence of intra-vs. intermolecular NH...OH (dynamic) interactions occurring in the “open-chain” unit and the anancomeric, axial vs. equatorial, amino-anchorage of the “closed-chain” unit. [...]

18

Analiza zbiornikowych właściwości skał przy wykorzystaniu zjawiska jądrowego rezonansu magnetycznego NMR

81%

Ciechanowska M. , Zalewska J.

Nafta-Gaz

|

2002

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tom R. 58, nr 1

32-44

PL

W artykule przedstawiono nowe możliwości oceny zbiornikowych właściwości skał, w tym zawartości wody związanej (nieredukowalnej), kapilarnej i wolnej w próbkach skal, przy wykorzystaniu jądrowego rezonansu magnetycznego NMR. Zaprezentowano wyniki badań przeprowadzonych na rdzeniach wiertniczych z rejonu przedgórza Karpat i Karpat oraz z Niżu Polskiego. Wdrożenie pomiarów NMR do praktyki przemysłowej umożliwi bieżącą weryfikację modeli interpretacyjnych profilowań elektrometrii wiertniczej, stosowanych do oceny nasyceń skal węglowodorami "ruchomymi".

EN

The paper presents some new possibilities to estimate reservoir properties of rocks, including content of bound (irreducible), capillary, and gravitational waters in rock samples, using nuclear magnetic resonance. Results of tests on cores from Carpathian Foredeep, Carpathians, and Polish Lowlands are presented. Implementation of NMR surveys into industrial practice will be helpful for current verification of interpretational models of electrometry logging, being applied to estimate saturation of rocks with "movable" hydrocarbons.

19

Direct determination of enantiomeric enrichment of chiral, underivatized aminophosphonic acids - useful for enantioselective bioconversion results evaluation

81%

Kozyra K. , Klimek-Ochab M. , Brzezińska-Rodak M. , Żymańczyk-Duda E.

Open Chemistry

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2013

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tom 11

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nr 9

1542-1547

EN

Abstract The possibility of applying 31P NMR spectroscopy for the determination of the enantiomeric excess of the racemic mixture of non-derivatized aminophosphonic acids with small side chains has been investigated. It is proven, that the effectiveness of the application of a chiral solvating agent strongly depends on the concentration of applied shift reagent and on the pH of the particular experiment. Effectual resolution protocols are elaborated for following phosphonic acids: 1-aminoethanephosphonic acid, 1-amino-2-methylpropanephosphonic acid, 1-aminophenylmethanephosphonic acid, 1-aminophenylmethane-phosphonic acid and 1-amino-2-phenylethanephosphonic acid. Graphical abstract [...]

20

Spectroscopic studies of Zn(II) halides complexes with 5,7-disubstituted derivatives of 1,2,4-triazolo-[1,5a]-pyrimidine

81%

Szłyk E. , Grodzicki A. , Pazderski L. , Sitkowski J.

Polish Journal of Chemistry

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1998

|

tom Vol. 72, nr 1

55-60

EN

Complexes of ZnX2 (X=Cl, Br, I, SCN) with 5,7-dimethyl-1,2,4-triazolo-[1,5a]-pyrimidine, 5,7-diphenyl-1,2,4-triazolo-[1,5a]-pyrimidine and 5,7-di-tert-butyl-1,2,4-triazolo-[1,5a]-pyrimidine were prepared and characterized by IR (100-4000 cm-1) and 1H, 13C, 15N NMR spectroscopies. Spectral data suggest pseudo-tetrahedral configuration around Zn(II) atom with N-3 bonded heterocycles. Halides and thiocyanates (N bonded) are in terminal positions.