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Now showing items 1 - 16 of 95

  • P446Role of the late sodium current in determining electrophysiological characteristics of cardiac ventricular myocytes

    Horvath, B   Veress, R   Baranyai, D   Kiss, D   Kurtan, B   Kovacs, Z   Szentandrassy, N   Banyasz, T   Magyar, J   Nanasi, P P  

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  • 2694. Worcester sauce for the rat: Kovacs, K. & Lazar, G. (1973). Observations on the nontoxicity of Worcestershire sauce in the rat kidney. Int. Z. VitamForsch. 43, 81

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  • Thermal stability and instrumented indentation in a Mg(60)Cu(30)Y(10) bulk metallic glass RID A-8091-2010 RID G-1977-2011

    Kovacs, Z   Castellero, A   Greer, AL   Lendvai, J   Baricco, M  

    The crystallisation and mechanical properties of the light alloy, Mg(60)Cu(30)Y(10) bulk metallic glass (BMG) have been investigated by differential scanning calorimetry and instrumented indentation. Generally, the low-temperature plasticity of BMGs can be improved by partial devitrification to give an ultra-fine crystal structure in the amorphous matrix. From the indentation tests, increases in hardness and elastic modulus were observed after both the first and second stages of crystallisation. Plastic instabilities have been observed in the instrumented-indentation loading curves, even for samples with a significant crystallised fraction. (C) 2004 Elsevier B.V. All rights reserved.
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    The reaction of the cyanoborane complexes L.BH2CN [where L = R3N (R = Me, Et, Pr, Bu); quinuclidine (Q) and Ph3P] with SbCl5 in CCl4 afforded 1:1 complexes. Coordination of antimony to the nitrogen atom of the cyano group was clearly implied by the 35-42 cm-1 shift of the nu(CN) cyano resonances towards the higher wavenumbers. The L.BH2CN.SbCl5 complexes, carrying a bridge-head CN function, readily transformed with Bu(t)Cl into the [BH2(L)CNBu(t)]SbCl6 tert-butylnitrilium salts with high crystallization ability. In the case of L = R3N and Q substituents partial chlorination of the B-H bond accompanied the formation of the nitrilium salt. The relatively weak coordination of the Bu(t)NC ligand in the above antimony complexes was indicated by the 2282-2292 cm-1 values observed for nu(CN), unexpectedly high for isonitrile complexes, as well as by the exchange reactions with strong donors (i.e. Me2SO, Q, DMAP), giving rise to the liberation of the Bu(t)NC. The synthetic utility of related complexes was shown by the highly efficient transformation of [BH2(L)CNBu(t)]SbCl6 into Me3.BH2C(O)NHBu(t) in an alkaline mediUM, whose acid hydrolysis furnishes Me3N.BH2COOH, a well-known and important compound in boron chemistry with high yield. Preparation of this substance with the presented new process, via the tert-butylnitrilium salt, is much more efficient than by means of the previously reported procedures employing the ethylnitrilium salt. The proposed structures of the new compounds L.BH2CN-SbCl5, [BH2(L)CNBu(t)]SbCl6 and Me3.BH2C(O)NHBu(t) were derived from IR, H-1 and B-11 NMR spectral data.
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  • Cross section measurements using gas and solid targets for production of the positron-emitting radionuclide O-14

    Kovacs, Z   Scholten, B   Tarkanyi, F   Coenen, HH   Qaim, SM  

    Irradiation of nitrogen with protons leads to (11)C (T(1/2) = 20.4 min) via the well-known (14)N(p, a) reaction. However, (14)O (T(1/2) = 70.6 s) and (13)N (T(1/2) = 10 min) are also formed as side products via the (14)N(p, n) and (14)N(p, d + pn) reactions, respectively. In this work detailed cross section measurements were carried out for those two side reactions up to 19.2 MeV using N(2) gas and nitrogen-containing solid targets. From the data, the thick-target yields and the exact level of radioactive impurities in (11)C were calculated. In the case of (14)O. the results also confirmed the possibility of producing this beta(+) emitting radionuclide in sufficient quantities for PET investigations.
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  • Synthesis, characterization, and bromine substitution of diamine complexes of carboxyborane and methoxycarbonylborane. Diazabora rings containing B-carboxyl and B-carboxylato groups RID E-9698-2010

    Gyori, B   Berente, Z   Kovacs, Z  

    DA . 2BH(2)CN (1) [DA = N,N,N',N'-tetramethylethanediamine (TMEDA, a), N,N,N',N'-tetramethylpropanediamine (TMPDA, b), and N,N,N',N'-tetramethylbutanediamine (TMBDA, c)], (DA . 2BH(2)CNEt)(BF4)(2) (2), and DA . 2BH(2)-COOH (3) complexes were prepared from Me2S solution of (BH2CN)(n) (--> 1 --> 2 --> 3) in fast procedures, differently from those usually applied. in good yields. Dimethyl esters (4) were prepared from 3 with methanol in very fast reactions catalyzed by HBr. 3 and 4 were transformed into DA . BH2COOH (5a,b) and DA . BH2COOMe (6) with DA in THF. Bromination of 3 in aqueous HBr yielded diamine-bis(monobromocarboxyboranes) (7), in vigorous conditions diamine-bis(dibromocarboxyboranes) (9) were produced. N-Bromosuccinimide in methanol transformed 3a,b directly into diamine-bis(bromomethoxycarbonylboranes) (8a,b). BrH . DA . BH(Br)COOH (10a,b) could be prepared from 5a,b with bromine in strongly acidic medium. N-Deprotonated 10a quickly transformed into a five-membered cyclic cation [TMEDA . BHCOOH](+) (cation in 12a) in both water and methanol. Thus, this ion was formed by dissolution of 10a in water, bromination of 5a or destroying one of the borane moieties in 7a by a base. N-Deprotonated 10b in water decomposed with a pH-dependent rate, but in methanol, in the presence of base, it transformed into a six-membered cyclic cation [TMPDA . BHCOOH](+) (cation in 12b). 8a,b could also be transformed into cyclic cations by destroying one of their borane moieties in methanol, (8b in absence of acids only). All cations were prepared as bromide, hexafluorophosphate and tetraphenylborate salts, pK(a) values of 12a,b (pK(a) = 5.5-5.6) are 3 units lower than those of amine-carboxyboranes. Zwitterions (18a,b) formed by their deprotonation were prepared. Cyclic cation [TMEDA . B(Br)COOH](+) (cation in 19a) formed on destroying one dibromocarboxyborane of 9a. This cation, quite a strong acid (pK(a) approximate to 4.2), was prepared as hexafluorophosphate and tetraphenylborate salt. The latter was transformed with aqueous KOH into the corresponding zwitterion (21a).
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  • The in vivo behavior of copper-64-labeled azamacrocyclic complexes

    Jones-Wilson, TM   Deal, KA   Anderson, CJ   McCarthy, DW   Kovacs, Z   Motekaitis, RJ   Sherry, AD   Martell, AE   Welch, MJ  

    The use of copper radioisotopes in imaging and therapy applications has created a greater need for bifunctional chelates (BFCs) for complexing copper radioisotopes to biomolecules. It has been demonstrated that the charge and lipophilicity of the Cu-BFC complex has a significant effect on the in vivo behavior of the radiolabeled Cu-BFC-biomolecule conjugate. To evaluate the effects of charge, stability, and macrocyclic backbone size on the biological behavior of Cu-64 complexes, a series of macrocyclic (CU)-C-64 complexes have been prepared, and the biodistributions of these agents were evaluated in normal Sprague-Dawley rats. Two macrocyclic backbones, dodecane and tetradecane, were evaluated; cyclen, DOTA, and DO2A were dodecane backbone derivatives, and cyclam, TETA, and et-cyclam were tetradecane backbone derivatives. The biodistributions of the Cu-64-labeled complexes correlated with differences in the size of the macrocycle backbone and the formal charge of the complex. All compounds showed uptake and clearance through the liver and kidneys; however, the positively charged Cu-64 complexes showed significantly higher uptake in both of these organs than did the negatively charged or neutral complexes. Cu-64-TETA, a negatively charged complex with the tetradecane backbone, had the most efficient clearance by 24 hours' postinjection. These data suggest that negatively charged complexes may have more favorable clearance properties when used as BFCs. NUCL MED BIOL 25;6:523-530, 1998. (C) 1998 Elsevier Science Inc.
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  • Equilibria and formation kinetics of some cyclen derivative complexes of lanthanides

    Szilagyi, E   Toth, E   Kovacs, Z   Platzek, J   Raduchel, B   Brucher, E  

    The kinetics of the formation reactions between the lanthanide(III) ions Ce(3+), Eu(3+) and Yb(3+) and four cyclen derivative ligands, DO3A-B, DO3A-ME, DO2A and DO2A-2B, were studied by spectrophotometry and a stopped-flow method at 25 degrees C in 1.0 M KCl solutions. The reactions were found to be of first order, which was interpreted in terms of the formation of a diprotonated intermediate, Ln(H(2)L)(+). The formation of products occurs via deprotonation and rearrangement of the intermediate, characterised by the rate constant, ii,. The rate law obtained, k(r) = k(OH)[OH ], is similar to those obtained for the formation reactions of DOTA and DOTA derivative complexes. The rate constants, k(OH), decrease with decrease in the number of charged carboxylate functional groups in the ligandsl the lowest rates were found for the formation of the DO2A complexes. The Formation rates increase significantly from Ce(3+) to Yb(3+) The direct proportionality between the formation rates and [H(+)](-1) was interpreted by assuming the equilibrium formation of a monoprotonated intermediate, Ln(HL), which undergoes deprotonation in a slow, rate-determining step. The validity of general base catalysis was detected in the formation reactions, which supports the assumption of the rate-controlling role of deprotonation of the monoprotonated intermediate. The protonation constants of the ligands DO3A-ME and DO2A-2B and the stability constants of their complexes were also determined. The ligand DO2A forms the usual complexes Ln(DO3A)(+) and the unusual species Ln(DO2A)(2)(-). In the complexes Ln(DO2A)(2)(-), the two ligands exhibit different coordination modes which were demonstrated by 1H NMR spectroscopy. (C) 2000 Elsevier Science S.A. All rights reserved.
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  • Examination of non-volatile organic compounds in red wines made in Eger

    Kovacs, Z   Dinya, Z  

    At present the analytical investigation of human consumption products, with special regard to the environmental and health connections, is basically important all over the world. Recently in several countries it was almost impossible to sell wine without a certificate of quality, based on modern, instrumental analytical methods. There is well-known medical-biological evidence, which has proved the antioxidant and vein wall-protecting effects of the nines in the case of frugal ingestion. On the other hand, they also play a part in the prevention of heart attacks. Regarding these biological effects the most important constituents of wines are the flavonoids, anthocyanidins, and their glycosides. Anthocyanins can be identified first of all in red wines. The organic constituents have characteristic antioxidant effects, which can play an important role in health protection. During our investigation we have studied the volatile and non-volatile organic compounds in different types of wines made in Eger and Tokay (Hungary). In our opinion these types of research projects have unique importance, from the economic viewpoint and in that they are not negligible in a national context. The separation and determination of volatile compounds was carried out by applying a Finnigan GSQ GC-MS apparatus and the non-volatile ones with HPLC-DAD and FAB MS techniques. (C) 2000 Elsevier Science B.V. All rights reserved.
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  • The use of production management techniques in the construction of large scale physics detectors

    Bazan, A   Chevenier, G   Estrella, F   Kovacs, Z   Le Flour, T   Le Goff, JM   Lieunard, S   McClatchey, R   Murray, S   Varga, L   Vialle, JP   Zsenei, M  

    The construction process of detectors for the Large Hadron Collider(LHC) experiments is large scale, heavily constrained by resource availability and evolves with time. As a consequence, changes in detector component design need to be tracked and quickly reflected in the construction process. With similar problems in industry engineers employ so-called Product Data Management (PDM) systems to control access to documented versions of designs and managers employ so-called Workflow Management software (WfMS) to coordinate production work processes. However, PDM and WfMS software are not generally integrated in industry. The Scale of LHC experiments, like CMS, demands that industrial production techniques be applied in detector construction. This paper outlines the major functions and applications of the CRISTAL system (Cooperating Repositories :and an Information System for Tracking Assembly Lifecycles) in use in CMS which successfully integrates PDM and WfMS techniques in managing large scale physics detector construction. This is the first time industrial production techniques have been deployed to this extent in detector construction.
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  • Model-driven development of recursive CORBA component assemblies

    Schmoelzer, G   Teiniker, E   Mitterdorfer, S   Kreiner, C   Kovacs, Z   Weiss, R  

    Software applications can be described as compositions of software components at an abstract level. In this paper we present a component modeling process which allows to design, model and implement recursive component compositions. We model nested components in a platform independent manner and provide a transformation to the CORBA Component Model (CCM), one example of a Platform Specific Model (PSM). Furthermore, an implementation technique of recursive component assembling compliant to the CCM standard is described, where the components structure is automatically generated by code generation tools.
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  • Excitation function of Te-122(d,n)I-123 nuclear reaction: production of I-123 at a low energy cyclotron

    Takacs, S   Azzam, A   Sonck, M   Szelecsenyi, F   Kovacs, Z   Hermanne, A   Tarkanyi, F  

    The excitation function of the Te-122(d, n)I-123 nuclear reaction has been measured from threshold up to 21 MeV by the stacked foil irradiation technique. Good agreement was obtained with the results of the recent model calculations but an energy shift of 2 MeV to lower energy can be seen when comparing with cross section measured earlier. Integral yields have been deduced from the measured excitation function and have been compared with experimental thick target yields found in the literature. A comparison of the yields of the proton and deuteron induced reactions for production of I-123 is given. (C) 1999 Elsevier Science Ltd. All rights reserved.
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    EMRI, J   KOVACS, Z   GYORI, B  

    Symmetrical bis(amine)(methoxycarbonyl)hydroboron(+1) cations have been prepared by treatment of trimethylaminebromo(methoxycarbonyl)borane [Me(3)N . BH(Br)COOMe] with an excess of tertiary amines (tetramethylethylenediamine, TMEDA; quinuclidine, Q), as well as pyridine bases (pyridine, Py; 4-methylpyridine, 4-Pic; 4-dimethylaminopyridine, DMAP) at higher temperature. Asymmetrical bis(amine)(methoxycarbonyl)hydroboron(+1) cations, which contain a chiral boron atom, have been synthesized, in good yields, in the reaction of 4-Pic . BH(2)COOMe and DMAP . BH(2)COOMe with amine perbromides (L . Br-2, L=Q, Py, 4-Pic, DMAP) performed in CH2Cl2 at room temperature. Besides these novel cationic carboxyboron compounds several new cationic cyanoboron complexes with an [LL'BH(CN)](+) composition have been prepared by utilizing the efficient method employing amine-perbromides (L . Br-2; L=Py, 4-Pic, DMAP) and amine-cyanoboranes (L'. BH2CN, L'=4-Pic, DMAP). This bis(amine)boronium cations have been prepared and characterized by IR, H-1 and B-11 NMR spectra as PF6 salts. Investigations of the water-soluble bis(amine)(methoxycarbonyl)hydroboron(+1) bromides, some of which could be prepared, showed that the hydrolytic stability of the ester group highly depends on the character of the amine: the complexes formed with tertiary amines are much more stable. This phenomenon is similar to that observed for the amine-(methoxycarbonyl)boranes (L . BH(2)COOMe, L=tertiary amine, pyridine base).
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    The macrocycles 1,4,10,13-tetraoxa-7,16-diezacyclooctadecane-7,16-bis(malonate) (oddm), -7-malonate (odmm) and -7,16-bis(alpha-methylacetate) (oddp) have been synthesized. Their protonation constants and the stability constants of their complexes ML with Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Zn2+, Cd2+ and Pb2+ have been determined by pH-potentiometry at a 1:1 metal-to-ligand ratio. The macrocycle oddm possesses high selectivity for the large metal ions. The complex [Sr(oddm)](2-) is two orders of magnitude more stable than [Ca(oddm)](2-) and the stability constant of [Pb(oddm)](2-) is six orders of magnitude larger than that of the corresponding zinc complex. The complexes of oddm with large metal ions (Sr2+ and Ba2+) possess rigid structures. while the average lifetimes of the metal-donor bonds are relatively large, and this is indicated; by the appearance of multiplet, signals in the H-1 NMR spectra.
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  • Excitation function of alpha-particle induced nuclear reactions on natural nickel

    Takacs, S   Tarkanyi, F   Kovacs, Z  

    Excitation functions have been measured for alpha-particle induced nuclear reactions on natural nickel leading to the formation of Zn-62,Zn-63,Zn-65, Cu-60,Cu-61,Cu-67, Ni-57 and Co-57 up to 25 MeV using the activation method. The status of corresponding cross sections measured earlier has been reviewed and compared with the data presented in this work. The application of the studied excitation functions in radioisotope production, activation techniques and monitoring of charged particle beams is discussed.
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