bluuebunny/crossref_metadata_2025_split huggingface dataset:
Properties of the energy spectrum of the Heisenberg molecular magnetN= 8
Authors: Labuz M. , Wal A. , Obermayr W. , Kuzma M. 
Published: January 2005

AbstractThe energy spectra of short rings of spinS= 1/2 particles with a nearest neighbour Heisenberg interaction have features which are common for various numbersNof spins. The example ofN= 8 was considered in detail, for which a complete set of eigenstates and eigenvalues is obtained by the Bethe Ansatz model. The results were compared with the rotational band model usually used for the interpretation of experimental data for antiferromagnetic molecular magnets. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
D charge‐density‐wave versus superconducting phase fluctuations in underdoped high‐Tc superconductors
Authors: Zeyher R. , Greco A. 
Published: January 2005

AbstractThe underdoped region in high‐Tc superconductors is characterized by an increase of the d‐wave gap and a decrease of the superconducting transition temperature Tc with decreasing doping. Two effects may cause such a behavior in the t–J model. On the one hand, superconductivity competes and may also coexist with a d charge‐density‐wave state. We discuss this effect by studying the phase diagram of the t–J model at large N (N is the number of internal degrees of freedom), the gap structure in the coexisting region and the resulting c‐axis tunneling spectra. On the other hand, we give rather general arguments in favor of a strong reduction of the phase stiffness near a Mott transition and calculate the resulting drop in Tc at low dopings due to thermal phase fluctuations. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interplay of orbitally polarized and magnetically ordered phases in doped transition metal oxides
Authors: Frésard Raymond , Raczkowski Marcin , Oleś Andrzej M. 
Published: January 2005

AbstractWe investigate the magnetic instabilities of the two‐dimensional model of interacting eg electrons for hole doping away from two electrons per site in the mean‐field approximation. In particular, we address the occurrence of orbitally polarized states due to the inequivalent orbitals, and their interplay with ferromagnetic and antiferromagnetic spin order. The role played by the Hund's exchange coupling JH and by the crystal field orbital splitting Ez in stabilizing one of the competing phases is discussed in detail. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Towards a solution of the consistent t‐matrix approximation for the U → ∞ Anderson impurity model
Authors: Keiter Hellmut , Baumgartner Klaus 
Published: January 2005

AbstractThe basic integral equations for the consistent t‐matrix approximation (CTMA) of the infinite U Anderson model are formally solved within the slow variable approximation. The solution is compared with a numerical C++ analysis using self adapting nets. Very good agreement is found. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum criticality and superconductivity in heavy‐electron metals
Authors: Steglich F. 
Published: January 2005

AbstractRecent work on strongly correlated electron systems realized in heavy‐fermion (HF) metals is reviewed. Particular emphasis is put on different types of antiferromagnetic quantum critical points (QCPs). HF superconductivity seems to be favored only in the presence of a QCP of conventional (spin‐density‐wave) rather than of unconventional nature. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Charge and magnetic order in mixed valence systems
Authors: Lemański R. 
Published: January 2005

AbstractWe analyze charge and magnetically ordered phases in systems described by a generalized Falicov‐Kimball model, with a spin‐dependent interaction term representing the Hund's rule. We study ground state properties of the model rigorously on the infinite 2D square lattice, but within the restricted configurational space, composed of all periodic phases (and their mixtures), for which the number of sites per unit cell is less or equal to 4. In the current work we focus on the mixed valence regime, where the total density of electrons is fixed and equal to 1. For a range of intermediate values of the interaction parameters we detected stable charge and magnetic superstructures of the form of stripes. They display various magnetic arrangements of the localized elctrons, including ferri‐ and antiferromagnetic, despite of the assumption of the ferromagnetic on‐site coupling. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bound states in the phase diagram of the extended Hubbard model
Authors: Bak M. 
Published: January 2005

AbstractThe paper shows how the known, exact results for the two electron bound states can modify the ground state phase diagram of extended Hubbard model (EHM) for on‐site attraction, intersite repulsion and arbitrary electron density. The main result is suppression of the superconducting state in favor of normal phase for small charge densities. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Scanning tunneling microscopy of monoatomic gold chains on vicinal Si(335) surface: experimental and theoretical study
Authors: Krawiec M. , Kwapiński T. , Jałochowski M. 
Published: January 2005

AbstractWe study electronic and topographic properties of the Si(335) surface, containing Au wires parallel to the steps. We use scanning tunneling microscopy (STM) supplemented by reflection of high energy electron diffraction (RHEED) technique. The STM data show the space and voltage dependent oscillations of the distance between STM tip and the surface which can be explained within one band tight binding Hubbard model. We calculate the STM current using nonequilibrium Keldysh Green function formalism. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin precession in spin‐polarized transport through an interacting quantum dot
Authors: Rudziński W. , Barnaś J. , Świrkowicz R. , Wilczyński M. 
Published: January 2005

AbstractSpin‐polarized transport through an interacting single‐level quantum dot coupled to two ferromagnetic leads with non‐collinear magnetizations is analyzed theoretically by means of the nonequilibrium Green function technique. We show that spin precession on the dot, which arises due to an effective exchange field originating from the interaction between the dot and external electrodes, may lead to negative differential conductance. Our results also prove that the diode‐like behavior in asymmetrical junctions with one electrode being half‐metallic is partially suppressed when magnetic moments of the electrodes become non‐collinear. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anxiolytic properties of Piper methysticum extract samples and fractions in the chick social–separation–stress procedure
Authors: Feltenstein Matt W. , Lambdin L. Corinne , Ganzera M. , Ranjith H. , Dharmaratne W. , Nanayakkara N. P. Dhammika , Khan Ikhlas A. , Sufka Kenneth J. 
Published: January 2005

AbstractPiper methysticum extract (Kava kava) possesses anxiolytic properties. However, it is unknown whether these effects are best predicted by total kavalactone content or by one or more of its primary kavalactone constituents. Using the chick social separation‐stress procedure as an anxiolytic bioassay, P. methysticum samples containing 12.8–100.0% total kavalactones (Exp. 1) and fractions containing 1–6 kavalactones of varying concentrations (0.1–67.5%; Exps. 2–3) were screened for activity and compared against a 5.0 mg/kg dose of chlordiazepoxide (CDP; Exp. 3). Eight‐day‐old chicks received IP injections of either vehicle or test compounds 30 min before being placed in the presence of two conspeciﬁcs or in isolation for a 3 min observation period. Dependent measures were ventral recumbency latency (sedation), distress vocalizations, and a measure of stress‐induced analgesia (in Exps. 1 and 2 only). P. methysticum extract samples attenuated distress vocalizations in a concentration‐dependent manner. The P. methysticum fraction that contained the highest concentration of dihydrokavain attenuated distress vocalizations in a manner equivalent to that of CDP. The extract samples and fractions that possessed anxiolytic properties did not possess the sedative properties found in CDP. Collectively, these ﬁndings suggest that dihydrokavain may be necessary and sufﬁcient in mediating the anxiolytic properties of P. methysticum extract. Copyright © 2003 John Wiley & Sons, Ltd.
Protection of jejunal crypts by RH‐3 (a preparation of Hippophae rhamnoides) against lethal whole body gamma irradiation
Authors: Goel H. C. , Salin C. A. , Prakash H. 
Published: January 2005

AbstractRH‐3, an alcoholic extract of whole berries of Hippopheae rhamnoides, has been demonstrated to provide radioprotective activity in terms of survival of mice against whole body lethal irradiation (10 Gy). It was, therefore, investigated for its mode of action by monitoring crypt survival, cellularity of crypts and villi and the magnitude of apoptosis in the GI tract.Administration of RH‐3 before irradiation (−30 min) increased the number of surviving crypts in the jejunum by a factor of 2.02 (p < 0.05) and villi cellularity by 2.5 fold (p < 0.05) in comparison to the irradiated control. RH‐3 administration before irradiation also reduced the incidence of apoptotic bodies in the crypts (p < 0.05) in a time dependent manner and increased cellularity in the crypts and villi (84 h post irradiation) as compared to control. Caspase‐3 activity was also signiﬁcantly lower in the mice administered RH‐3 before irradiation as compared to irradiated control.This study indicates that reduction in the radiation induced loss of cellularity of crypts and villi and also decrease in frequency of apoptosis could have contributed towards protection of mice treated with RH‐3 before irradiation. The cellular and molecular mechanisms of radioprotection by Rh‐3 need to be investigated further in detail. Copyright © 2003 John Wiley & Sons, Ltd.
HIV‐1 integrase inhibitory substances from Coleus parvifolius
Authors: Tewtrakul Supinya , Miyashiro Hirotsugu , Nakamura Norio , Hattori Masao , Kawahata Takuya , Otake Toru , Yoshinaga Tomokazu , Fujiwara Tamio , Supavita Tanomjit , Yuenyongsawad Supreeya , Rattanasuwon Pranee , Dej‐Adisai Sukanya 
Published: January 2005

AbstractFor the purpose of discovering anti‐HIV‐1 agents from natural sources, water and EtOH extracts of 50 Thai plants were screened for their inhibitory activity against HIV‐1 integrase (IN), an enzyme essential for viral replication. Of these plants, an EtOH extract of Coleus parvifolius Benth. (aerial parts) showed potent activity against HIV‐1 IN with an IC50 value of 9.2 µg/mL. From this extract, 11 compounds were isolated and identiﬁed as luteolin 5‐O‐β‐d‐glucopyranoside (1), luteolin (2), luteolin 7‐methyl ether (3), luteolin 5‐O‐β‐d‐glucuronide (4), 5‐O‐β‐d‐glucopyranosyl‐luteolin 7‐methyl ether (5), rosmarinic acid (6), rosmarinic acid methyl ester (7), daucosterol (8), a mixture of α‐ and β‐amyrin (9, 10) and phytol (11). Of these compounds, rosmarinic acid methyl ester (7), rosmarinic acid (6), luteolin (2) and luteolin 7‐methyl ether (3) exhibited inhibitory activities against HIV‐1 IN with IC50 values of 3.1, 5.0, 11.0 and 11.0 µM, respectively. Among rosmarinic acid derivatives, the HIV‐1 IN inhibitory activity increased in turn for a dimer (IC50 = 5.0 µM), a trimer (IC50 = 1.4 µM), and a tetramer (IC50 = 1.0 µM). Copyright © 2003 John Wiley & Sons, Ltd.
Activity of Zanthoxylum clava‐herculis extracts against multi‐drug resistant methicillin‐resistant Staphylococcus aureus (mdr‐MRSA)
Authors: Gibbons Simon , Leimkugel Julia , Oluwatuyi Moyo , Heinrich Michael 
Published: January 2005

AbstractIn a continuing search for compounds with antibiotic activity against methicillin‐resistant Staphylococcus aureus (MRSA) possessing multidrug efﬂux systems, we have demonstrated activity associated with extracts from Southern prickly ash bark, Zanthoxylum clava‐herculis. Bioassay‐guided isolation of an alkaloid extract led to the characterization of the benzo[c]phenanthridine alkaloid chelerythrine as the major active principle. This compound exhibited potent activity against strains of MRSA, which were highly resistant to clinically useful antibiotics via multidrug efﬂux mechanisms. Copyright © 2003 John Wiley & Sons, Ltd.
Correction of the high blood viscosity syndrome by a mixture of diquertin and ascorbic acid in vitro and in vivo
Authors: Plotnikov M. B. , Aliev O. I. , Maslov M. Ju. , Vasiliev A. S. , Tjukavkina N. A. 
Published: January 2005

AbstractDiquertin was shown to diminish blood viscosity, to decrease the aggregation of erythrocytes, and to increase their deformability using a model of the high blood viscosity syndrome in vitro. A mixture of Diquertin with Ascorbic Acid was more effective in improving rheological indicators of blood, then either Diquertin or Tanakan. On a model of chronic brain ischemia, which is accompanied by signiﬁcant deterioration of the rheological properties of blood, it was shown that a therapy with a mixture of Diquertin and Ascorbic Acid decreases the expression of the high blood viscosity syndrome. Copyright © 2003 John Wiley & Sons, Ltd.
In vitro cytotoxicity activity of diosquinone, a naphthoquinone epoxide
Authors: Adeniyi B. A. , Robert M. F. , Chai H. , Fong H. H. S. 
Published: January 2005

AbstractDiosquinone [1], a naphthoquinone epoxide previously isolated from the root bark of Diospyros mespiliformis (Hostch) and D. tricolor [Ebenaceae] is been assessed for cytotoxicity activity against ten cancer cell lines by standard NIH method. The ethno‐pharmacological claim of this plant and the previously observed good antibacterial activity of this compound among the others isolated from this plant suggest its probable cytotoxicity activity.Diosquinone was observed to be very active against most of the cancer cell lines. It shows very good activity against all the cell lines tested with ED50 value ranging between 0.18 µg/ml. against Human Glioblastoma (U373) to 4.5 µg/ml. against Hormone dependent human prostrate cancer( LNCaP). Copyright © 2003 John Wiley & Sons, Ltd.
Pharmacological activities of stromata of Cordyceps scarabaecola
Authors: Yu K. W. , Kim K. M. , Suh H. J. 
Published: January 2005

AbstractThe chemical components of freeze‐dried stromata from Cordyceps scarabaecola were examined. The stromata consisted of crude carbohydrates (55.1%) and crude proteins (14.2%). The stromata were also composed of a low content of crude ash (6.6%) and fat (1.5%). The composition of the carbohydrate in the stromata included a large quantity of glucose (46.6%), mannose (35.4%) and galactose (18.0%). The acidic amino acids such as glutamic acid (32.1 mg/g) and aspartic acid (24.7 mg/g) were present in a large quantity. The extracts of stromata did not reveal any inhibitory activity for AChE in vitro. It was observed that a hot‐water extract (HW) of the stromata contributed signiﬁcantly to the anticoagulant activity (60 s coagulating time) and anticomplementary activity (62% of ITCH50 value). The MeOH‐soluble fraction (M) from the freeze‐dried stromata inhibited TPA‐induced O2− generation as effectively as the positive control, genistine 27%. The hot‐water extract (HW) showed the most potent intestinal immune system modulation activity and the MeOH‐soluble fraction (M) had intermediate activity. Copyright © 2003 John Wiley & Sons, Ltd.
Mitigation of thyroxine‐induced hyperglycaemia by two plant extracts
Authors: Tahiliani Pankaj , Kar Anand 
Published: January 2005

AbstractExtracts of Trigonella foenum‐graecum (TFG) seed and Allium sativum (AS) bulb were evaluated for their efﬁcacy to ameliorate l‐thyroxine (l‐T4) induced hyperglycaemia in rats. Simultaneously, the serum cholesterol concentration, a supporting parameter for thyroid function, was also estimated. Thyroxine treatment in rats (300 µg/kg b. wt./day) increased the levels of both the thyroid hormones, namely thyroxine (T4) and tri‐iodothyronine (T3) with a concomitant elevation in serum glucose concentration and a reduction in serum cholesterol level. Administration of TFG (220 mg/kg/day) and AS (500 mg/kg/day) extracts in hyperthyroid animals decreased the serum glucose concentration as well as the serum thyroid hormones. For comparison, propyl thiouracil (PTU), an antithyroid compound, was used as the standard at a daily dose of 10 mg/kg. The reductions in serum glucose and thyroid hormone concentrations in the plant extract treated groups were comparable to that in PTU treated animals. Our ﬁndings indicate that TFG seed and AS bulb extracts may prove to be effective in the treatment of thyroxine‐induced hyperglycaemia. Copyright © 2003 John Wiley & Sons, Ltd.
Toxicological effects of α‐solamargine in experimental animals
Authors: Al Chami Lina , Méndez Ramón , Chataing Bernardo , O'Callaghan James , Usubillaga Alfredo , LaCruz Luis 
Published: January 2005

Abstractα‐Solamargine isolated from the fresh fruits of Solanum americanum Miller was studied for its toxicity. Lethality studies in rats showed a dose‐mortality relationship with a LD50 of 42 mg/kg body weight intraperitoneally. The chronic and subchronic toxicity investigations indicated that the size of the glycoalkaloid dose was more important than the total glycoalkaloid intake. No appreciable toxic effects were observed at doses below 35 mg/kg body weight as indicated by blood parameters, enzyme levels and histological sections of kidney, liver and cardiac muscle. α‐Solamargine did not affect the weight of the testes and epididymis or the number of spermatozoa but produced a slight irritation and congestion in the epididymis and testis at doses up to 50 mg/kg body weight. Copyright © 2003 John Wiley & Sons, Ltd.
Protective effect of Mangifera indica L. extract (Vimang®) on the injury associated with hepatic ischaemia reperfusion
Authors: Martínez Sánchez Gregorio , Rodríguez H. María A. , Giuliani Attilia , Núñez Sellés Alberto J. , Pons Rodríguez Niurka , Fernández Olga Sonia León , Re L. 
Published: January 2005

AbstractThe effect of Mangifera indica L. extract (Vimang®) on treatment of injury associated with hepatic ischaemia/reperfusion was tested. Vimang® protects from the oxidative damage induced by oxygen‐based free radicals as shown in several in vitro test systems conducted. The ability of Vimang® to reduce liver damage was investigated in rats undergoing right‐lobe blood ﬂow occlusion for 45 min followed by 45 min of reperfusion. The ischaemia/reperfusion model leads to an increase of transaminase (ALT and AST), membrane lipid peroxidation, tissue neutrophil inﬁltration, DNA fragmentation, loss of protein ‐SH groups, cytosolic Ca2+ overload and a decrease of catalase activity. Oral administration of Vimang® (50, 110 and 250 mg/kg, b.w.) 7 days before reperfusion, reduced transaminase levels and DNA fragmentation in a dose dependent manner (p < 0.05). Vimang® also restored the cytosolic Ca2+ levels and inhibited polymorphonuclear migration at a dose of 250 mg/kg b.w., improved the oxidation of total and non protein sulfhydryl groups and prevented modiﬁcation in catalase activity, uric acid and lipid peroxidation markers (p < 0.05). These data suggest that Vimang® could be a useful new natural drug for preventing oxidative damage during hepatic injury associated with free radical generation. Copyright © 2003 John Wiley & Sons, Ltd.
Direct tandem mass spectrometric analysis of amino acids in dried blood spots without chemical derivatization for neonatal screening
Authors: Nagy Kornél , Takáts Zoltán , Pollreisz Ferenc , Szabó Teréz , Vékey Károly 
Published: January 2005

AbstractNeonatal screening performed by electrospray tandem mass spectrometry is a powerful technique in clinical diagnostics. In the present paper an alternative to the widely accepted method involving butylation has been developed. In the new method butylation is not required, and multiple reaction monitoring (MRM) was used instead of constant neutral loss scanning. The method was optimized for detection of 23 L‐amino acids in their native form. Quantitation was based on isotope‐labeled internal standards, calibration curves were linear from 0 to 500 μmol/L, and detection limits were in the range 2–42 μmol/L. The utility of the present technique is illustrated in the case of one neonate suffering from citrullinaemia. Copyright © 2003 John Wiley & Sons, Ltd.
Tandem mass spectrometric analysis of glyphosate, glufosinate, aminomethylphosphonic acid and methylphosphinicopropionic acid
Authors: Goodwin Lee , Startin James R. , Goodall David M. , Keely Brendan J. 
Published: January 2005

AbstractA detailed MSn study of glyphosate, glufosinate and their main metabolites, aminomethylphosphonic acid and methylphosphinicopropionic acid, using an ion trap mass spectrometer, was performed. The analytes show good response in negative ion electrospray mass spectrometry (ES‐MS) as [MH]− ions. Tandem‐MS spectra reveal a wealth of structurally specific ions, allowing characterisation of the fragmentation pathways of the four analytes in their native form for the first time. The ions formed at each stage of fragmentation reveal ions common to each analyte, such as phosphinate, as well as analyte specific transitions. Simplex optimisation allows optimum trapping and fragmentation parameters to be determined leading to improved response for particular transitions and transition sequences, and revealing previously unseen ions. Copyright © 2003 John Wiley & Sons, Ltd.
Identification of caffeic acid derivatives in Actea racemosa (Cimicifuga racemosa, black cohosh) by liquid chromatography/tandem mass spectrometry
Authors: Li Wenkui , Sun Yongkai , Liang Wenzhong , Fitzloff John F. , van Breemen Richard B. 
Published: January 2005

AbstractCaffeic acid derivatives occurring in black cohosh [Cimicifuga racemosa (L.) Nutt., Actaea racemosa (Ranunculaceae)], some of which may have pharmacological activity, were analyzed using high‐performance liquid chromatography (HPLC) electrospray ionization tandem mass spectrometry (ESI‐MS/MS) with the aim of developing a methodology for their rapid identification in a complex plant matrix. Based on these studies, structurally characteristic product ions and neutral molecule losses were identified, which were then used during LC/MS/MS with product ion scanning, precursor scanning and constant neutral loss scanning to detect caffeic acid derivatives in a crude extract of black cohosh. Several caffeic acid derivatives were detected, and the identification of six of them were confirmed by comparison with authentic standards including caffeic acid, ferulic acid, isoferulic acid, fukinolic acid, cimicifugic acid A, and cimicifugic acid B. Four other compounds were detected that appeared to be caffeic acid derivatives based on LC/MS/MS retention times, molecular weights, and fragmentation patterns during MS/MS. Since standards were unavailable for these four compounds, they were tentatively identified using LC/MS/MS as cimicifugic acid E, cimicifugic acid F, dehydrocimicifugic acid A, and dehydrocimicifugic acid B. Dehydrocimicifugic acid A and dehydrocimicifugic acid B have not been reported previously to be constituents of black cohosh. Copyright © 2003 John Wiley & Sons, Ltd.