Wyniki wyszukiwania - BazTech

1

Currents induced by standard movements in a 3T static magnetic field

Valbonesi S., Barbiroli M., Frullone M., Papotti E., Vanore A.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 7b

145-147

EN

MRI magnets generates strong and uniform magnetic fields within the field of view, but spatial field gradients are present outside this central region, and as consequence people moving within magnet room experience time-varying magnetic field inducing electric fields and currents in tissues. Aim of this study is the assessment, through direct static field measurements and model based calculations, of induced currents at trunk and head as effect of translating or rotational body movement within the magnet room.

PL

Urządzenie do rezonansu magnetycznego generuje bardzo silne stałe pole magnetyczne w polu obserwacji ale gradient przestrzenny pola istnieje na zewnątrz pola obserwacji. Konsekwencją tego jest narażenie osób poruszających się w wewnątrz pomieszczenia na ekspozycję w polu elektromagnetycznym, co skutkuje indukowaniem się pola elektrycznego i prądów w ich tkankach. Celem artykułu jest oszacowanie poprzez pomiary stałego pola magnetycznego oraz symulację komputerową wartości prądów indukowanych w tułowie i głowie osób poruszających się w pomieszczeniu.

2

Niechromatograficzne techniki instrumentalne w analizie olejów roślinnych

Gromadzka J., Wardencki W.

Analityka : nauka i praktyka

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2009

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nr 3

29-32

3

Badania struktury fazowej recyklatu poli(tereftalanu etylenu) z zastosowaniem techniki magnetycznego rezonansu jądrowego

Czarnecka-Komorowska D., Jurga J.

Archiwum Technologii Maszyn i Automatyzacji

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2005

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Vol. 25, nr 1

179-187

PL

W artykule przedstawiono wyniki badań poli(teraftalanu etylenu) (PET) poddanego wielokrotnemu przetwórstwu. Podano temperaturowe zmiany szerokości linii rezonansowych tego materiału obserwowanych w technice magnetycznego rezonansu jądrowego (NMR). Badaniom poddano nieprzetworzony PET oraz ten sam materiał 6-krotnie przetworzony metoda, wtryskiwania. Badania wykazały, że wielokrotne przetwarzanie PET prowadzi do zwiększenia udziału fazy amorficznej polimeru na skutek degradacji łańcucha, a także do ponownej krystalizacji krystalicznej części zdegradowanych łańcuchów.

EN

The paper presents the temperature results of NMR broad line experiment for semicry stal line poly(ethylene teraphthalate) - PET after reprocessing. The specimens made of virgin and recycled PET after 6-cycles of processing were investigated. This study showed that reprocessing caused the increase of the amorphous phase of polymer as results degradation of the molecular chains and also it caused a additional crystallization in the crystalline part of the degraded chains.

4

129Xe NMR of adsorbed xenon and 1H NMR imaging: new methods to study the diffusion of gaseous hydrocarbons in a fixed bed of zeolite

N'Gokoli-Kekele P., Springuel-Huet M.-A., Bonardet J.-L., Dereppe J.-M., Fraissard J.

Bulletin of the Polish Academy of Sciences. Chemistry

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2002

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Vol. 50, No. 2

249-258

EN

129Xe NMR of adsorbed xenon used as a probe and (1)H NMR imaging have been used to study the diffusion of hydrocarbons (benzene, n-hexane, paraxylene) during their adsorption or desorption in a fixed bed of zeolite crystallites. The simulation of experimental (129)Xe spectra using the nonuniform or the shrinking core models gives the concentration profiles of hydrocarbons, in the bed and in the zeolite crystallites, during their adsorption and leads to intracrystalline diffusion coefficients in good agreement with the literature. The (1)H NMR imaging allows one to visualize the progression of the diffusing molecules in the zeolite bed and also to determine their intracrystalline diffusion coefficients in the simplest cases.

5

Tworzenie modeli CAD na podstawie danych uzyskanych z badań tkanek metodą magnetycznego rezonansu jądrowego

Stankiewicz W., Roszak R.

Zeszyty Naukowe Politechniki Poznańskiej. Maszyny Robocze i Transport

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2001

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Nr 53

47-52

PL

Magnetyczny rezonans jądrowy jest alternatywą badań rentgenowskich, pozwalającą na uzyskiwanie danych na temat tkanek w sposób nieszkodliwy dla zdrowia pacjenta. Dane w postaci kolejnych obrazów warstw tkanki są wykorzystywane w diagnostyce wielu chorób. Po ich przetworzeniu na zbiór punktów i linii oraz połączeniu w powierzchnie i bryły, uzyskuje się modele tr6jwymiarowe, analogiczne do stosowanych w CAD. W pracy przedstawiono algorytm przetwarzania danych NMR na modele 3D, wraz z przykładami zastosowań. Może on posłużyć do przygotowania protez, analizy strukturalnej tkanek czy prowadzenia wirtualnych operacji chirurgicznych.

EN

Nuclear magnetic resonance is a good alternative for X -Ray examinations, allowing tissue data acquiring harmless to patient' s healtil. This data, in a form of subsequent layers of tissue, may be used for detection of many diseases. In tills paper, tile algoritiun for conversion of grayscale NMR images into 3D CAD model is presented. The program written by authors converts series of images into set of points or lines. Then they are merged into 3D model containing surfaces and solids. This model may be used in prosthetics, structural analysis of tissues or in virtual surgery .

6

Spin-orbit coupling effects in ozone depletion spectroscopy

Minaev B., Bilan E.

Bulletin of the Polish Academy of Sciences. Chemistry

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2001

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Vol. 49, No. 2

133-164

EN

The structure of halogen oxides, XO (X = Cl, Br, I), stability of their anions and the UV-visible absorption spectra of hypohalous acids, HOX, are studied by ab initio methods with account of spin-orbit coupling (SOC) effects. The unrestricted Hartree-Fock (UHF) method, multi-configuration self-consistent field (MCSCF) calculations with linear and quadratic response techniques and MRCI method have been implemented. The Breit-Pauli form of the SOC operator is used. NMR spectra of HOI, HOBr and IO~ species are predicted. Photodissociation of the HOX molecules, which is crucial for the catalytic ozone-destruction cycle, is critically reviewed and analyzed. The singlet-triplet (S-T) transition to the lowest triplet state T\(XlA1 —ť3 A") is responsible for the weak long-wavelength tail absorption which induces photodissociation of these molecules. These absorption bands (380, 450 and 460 nm for X = Cl, Br and I, respectively) have small cross section, about (4, 15 and 24)xlO cm , respectively, but still are important for dissociation process HOX —ť X + OH and ozone concentration, since the stratosphere is transparent for such radiation. The second, more intense band (305, 350 and 406 nm for X = Cl, Br and I, respectively) is produced by two overlapping S-S and S-T transitions. The first singlet-singlet transition, SQ — Si, is relatively weak; it is responsible for about 95% of the cross section in HOC1; in HOBr the SQ — T% transition to the second triplet state contributes to this absorption band much more (about 50%); in HOI this is mostly the So — TI absorption. This band is strongly enhanced in HOI molecule because of the T% - 84 SOC mixing and its wavelength is red-shifted. In order to check this assignment of very peculiar HOI spectrum, the ESR and UV spectral properties of IO radical have been calculated with the same approximation. A good agreement with the ESR spectrum for the calculated nuclear quadrupole coupling constant and SOC splitting makes credit to the accuracy of HOI spectral interpretation. The third, most intensive UV absorption band (242, 280 and 340 nm for X = Cl, Br and I, respectively) in hypohalous acids is determined by the O—X bond polarized S-S transition to the second singlet exited state (X A' —ť 2 A'). All excited states are dissociative. The SOC account is of crucial importance for the absorption cross section calculations of the HOX molecules in the UV-visible part of solar actinic flux and for their lifetime in lower stratosphere. Account of SOC effect is also very important for the lifetime prediction of the halogen oxides and their anions.

7

Utlenianie filmów węglowych - badania metodą 13C NMR

Zawadzki J., Wiśniewski M.

Karbo

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2000

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Nr 10

345-347

PL

Metodę (13) 3C CP-MAS NMR wykorzystano do spektralnych badań zmian struktury chemicznej podczas procesu wstępnej karbonizacji przez utlenianie celulozy w atmosferze tlenu. Wzrost stężenia powierzchniowych tlenków kwasowych badano również w trakcie procesu utleniania w atmosferze tlenu lub w roztworze HNO(3) węgli aktywnych otrzymywanych drogą niskotemperaturowej (600°C) karbonizacji celulozy w próżni.

EN

The (13)C CP- MAS NMR has been employed for spectrum investigations of chemical structure changes during the initial carbonisation process by cellulose oxidation in the atmosphere of oxygen. A rise of the concentration of surface acidic oxides was measured during the oxidation process, in oxygen atmosphere or in HNO3 solution, of active carbons obtained from low temperature (600°C) cellulose carbonisation in a vacuum surrounding.

8

Solvation and proton transfer phenomena in phenol derivative-tertiary amine-aprotic solvent systems

Ilczyszyn M.

Bulletin of the Polish Academy of Sciences. Chemistry

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2000

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Vol. 48, No. 1

91-100

EN

Proton transfer (PT) equilibria inside hydrogen-bonded complexes of phe-nols (AH) with triethylamine and JV-methylpiperidine (B), A-H...B A - o -H-B+, dissolved in cooled (up to 113 K) aprotic solvents are analysed using H NMR results. Two categories of situations, depending on the acid and base initial concentrations, are considered: slower and faster PT for the Cg : CAg w 2 and Cg : CAu > 2 solutions, re-spectively. They are characterised by enthalpy and entropy of PT and interpreted as a result of relations between the proton transfer and solvation phenomena. In strongly cooled CB : CAH Ť 2 solutions the intra-complex proton motion is probably coupled to the motion of the solvating base molecule. This phenomenon is qualitatively described by the density function of the energy attraction between the bridging AHB proton and the solvating amine molecule. In the CB : CAH > 2 solutions this mechanism does not work probably and the hydrogen bonded ion-pairs are strongly solvated by the neighbour amine molecules.

9

Solid state NMR spectroscopy as a tool to investigation of structure and dynamics of amino acids and model peptides

Ganicz K.

Bulletin of the Polish Academy of Sciences. Chemistry

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2000

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Vol. 48, No. 1

57-76

EN

The paper describes new approaches to investigate amino acids and peptides in the solid state employing modern NMR spectroscopy. The application of C and N principal elements of the chemical shift tensors to analysis of local environment of peptide unit, carboxylate group and amine group is discussed. The application of NMR techniques to investigate hydrogen bonding pattern is described. Molecular dynamics and deuterium NMR spectroscopy are presented. The sequences to measure the intra- and intermolecular distances as well as torsional angles in homo- and heteronuclear systems are discussed.

10

Physical image vs. structure relation, 5 [1]. Multinuclear NMR structural study on some hydrazones of O,O-Dialkyl 1-Oxoalkanephosphonates

Nazarski R. B., Gralak D. K., Kudzin Z. H.

Bulletin of the Polish Academy of Sciences. Chemistry

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2000

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Vol. 48, No. 1

27-33

EN

An unambiguous method for determination of the configuration of any single 0,0-dialkyl 1-oxoalkanephosphonate hydrazones based on H, C, P NMR data has been elaborated; the use of 1 JCp (P-C=N) couplings is the most fruitful. The 12C/13C isotope effects on the P chemical shifts of selected compounds have been measured. For primary hydrazones the E/Z isomerisation with stabilisation of their Z forms through an intramolecular H-bonding has been proven. In addition, for the latter stereoisomers small scalar couplings between H-bonded groups N-H.. .O=P have been found, JHP 2.4-3.4 Hz. The possibility of the across H-bridge transfer of spin-spin interactions in these forms is also discussed.

11

Physical image vs. structure relation, 4[1]. Configuration and conformation determination of some bicyclic lactams by 1H NMR and theoretical methods

Nazarski R. B., Leśniak S.

Bulletin of the Polish Academy of Sciences. Chemistry

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2000

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Vol. 48, No. 1

17-25

EN

Resolution-enhanced H NMR spectra of six single diastereomers of fused-ring sulfur-containing lactams have been recorded and interpreted. In joint analysis of derived couplings Ť/HH> performed with use of the Karplus-Conroy type relationship and results of static MM calculations, it was possible to determine the configuration of title compounds and the conformation elucidation of their six-membered rings. Simultaneously, the stereochemistry of the observed ring-closure reaction was determined. The application of TNDO/2 method for the prediction of n JHH values is also briefly discussed.

12

Non-classic constraints in protein structure determination

Ejchart A.

Bulletin of the Polish Academy of Sciences. Chemistry

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2000

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Vol. 48, No. 1

1-11

EN

Recently, three new types of structural constraints have been introduced into the procedures of protein structure determination. Application of residual dipolar cou-plings, interference effects, and dependence of heteronuclear relaxation times on rotational diffusion anisotropy opens new perspectives for the functional and structural NMR studies of proteins.

13

Nitrogen NMR investigation of compounds containing 1,3-Diphenyl- and 2,3-Diphenyl-1,2,3,4-tetrazolium ring

Jaźwiński J.

Bulletin of the Polish Academy of Sciences. Chemistry

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2000

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Vol. 48, No. 1

35-46

EN

The compounds containing either 1,3-diphenyl-1,2,3,4-tetrazolium or 2,3-diphenyl-1,2,3,4-tetrazolium ring have been investigated by means of 14N and 15N NMR technique. The effects of structure variation on the change in N chemical shifts are dis-cussed. Positive charge distribution within tetrazolium ring has been examined by N NMR technique.

14

Effects of intermolecular interactions on the 1H, 13C and 14N NMR chemical shifts of N,N-Dimethylformamide dissolved in monosubstituted benzenes

Jackowski K., Makulski W., Trenkner-Olejniczak Z.

Bulletin of the Polish Academy of Sciences. Chemistry

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2000

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Vol. 48, No. 1

81-89

EN

1 H,13 C and 14 N NMR chemical shifts have been used to monitor the dilution process of JV,7V-dimethylformamide (DMF) in monosubstituted benzenes. Both the proton and carbon chemical shifts of non-equivalent methyl groups in DMF are spectacularly influenced by ASIS (Aromatic Solvent Induced Shift) effects at the low concentration of a solute. On the other hand, the destruction of DMF liquid structure itself is better seen when the 13C chemical shift of a carbonyl carbon and the 14N shift are verified. A good correlation between the latter NMR chemical shifts has been found. It is shown on the basis of GIAO-CHF model calculations that the destruction of solute dipole-dipole dimers may be responsible for the increase of carbonyl carbon and nitrogen shielding constants of DMF in solvents.

15

Effect of planar substituents on magnetic shielding tensors of sp-hybridized carbon nuclei in substitueted acetylenes - a GIAO-CHF study

Jackowski K., Molchanov S., Gryff-Keller A.

Bulletin of the Polish Academy of Sciences. Chemistry

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2000

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Vol. 48, No. 1

77-80

EN

The magnetic shielding tensors for sp-hybridized carbons in a series of acetyl-enic compounds XC=CH (X = H, NH2, OMe, NMe2) Ph, CHO, CC1O and NO2) have been calculated using the GIAO-CHF method and the standard 6-31G** basis set. The substituent effect has appeared to be large but independent of the 7r-electronic properties of the substituent.

16

2,1,3-Benzoselenodiazole-5-carbaldehyde and derivatives preparations, 13C, 15N and 77Se NMR spectroscopy

Morkved E. H., Bjorlo O., Schilf W., Bernatowicz P.

Bulletin of the Polish Academy of Sciences. Chemistry

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2000

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Vol. 48, No. 1

47-56

EN

2,l,3-Benzoselenadiazole-5-carbaldehyde 5 has been prepared in 53% overall yield from 5-methyl-2,l,3-benzoselenadiazole 1, by a four-step synthesis. Compounds 1-5 and 2,1,3-benzo-selenadiazole 8 have been analysed by 1H, 13C, 15N and 77Se NMR spectroscopy, and structural implications are discussed. Some imines and diimines were prepared from 5, but low solubility in organic solvents made these compounds of little interest for further studies.