bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mössbauer study of the relationship between magnetic properties and Jahn–Teller distortion in La1–xBax(Mn,Fe)O3 perovskites
Authors: Kou Zhi‐qi , Ma Xiao , Di Nai‐li , Li Qing‐an , Cheng Zhao‐hua 
Published: September 2005

AbstractThe local structural distortion and its effect on the magnetic and magnetotransport properties of the Fe‐doped La1–xBaxMnO3 (0.00 ≤ x ≤ 0.35) compounds were investigated by means of X‐ray diffraction, Mössbauer spectroscopy, and magnetization measurements. The Mössbauer spectra show clear evidence of the local structural distortion of the Mn(Fe)O6 octahedron on the basis of non‐zero nuclear quadrupole interactions for high‐spin Fe3+ ions. It was found that the local structural distortion decreases significantly with the introduction of a few per cent of Ba, reaches a minimum around x = 0.13, and then increases slightly on further increasing the Ba concentration. The Ba‐concentration dependence of the Jahn–Teller coupling strength estimated from the Mössbauer results was found to be consistent with the magnetic properties. Consequently, the connection between this local structural distortion and the colossal magnetoresistive behavior of this family of materials can be well explained. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the magnetic compensation effect of lithium‐chromium ferrites Li0.5CrxFe2.5–xO4 (0 ≤ x ≤ 1.55)
Authors: Rais A. , Gismelseed A. M. , Al‐Omari I. A. 
Published: September 2005

AbstractLithium‐chromium ferrites Li0.5Fe2.5–xCrxO4 (0 ≤ x ≤ 1.55) were studied using X‐ray diffraction, magnetization measurements and Mössbauer spectroscopy. X‐ray diffraction patterns show that all samples have cubic spinel structure. The temperature dependent magnetic measurements revealed that a magnetic compensation point appears at chromium concentration x = 1.05, 1.25 and 1.55. Moreover, it was observed that the Curie temperature TC decreases and approaches the compensation temperature TK as Cr3+ substitution for Fe3+ increases. The magnetization data at all concentrations are discussed in the light of Néel's molecular field model taking into account the cation distributions obtained using the analysis of Mössbauer spectra. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simultaneous measurement of wafer curvature and true temperature during metalorganic growth of group‐III nitrides on silicon and sapphire
Authors: Krost A. , Schulze F. , Dadgar A. , Strassburger G. , Haberland K. , Zettler T. 
Published: September 2005

AbstractWe present an in situ method for the simultaneous determination of wafer curvature and true growth temperature during metalorganic vapor phase epitaxy of group‐III‐nitrides on silicon. The measurement configuration allows determining the wafer curvature by the reflections of parallel laser beams, and at the same time, the wafer temperature is measured by emissivity‐corrected pyrometry. The bending of the substrates due to strained layers and unequal thermal expansions coefficients causes a change in the surface temperature of the wafer, although the monitored process temperature is constant. Thereby both kinds of curvatures, concave and convex, lead to an opposed temperature variation. Thus, by growing LED structures on silicon a temperature shift up to 45 K with respect to the susceptor was observed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Real‐time diagnostics for metalorganic vapor phase epitaxy
Authors: Aspnes D. E. 
Published: September 2005

AbstractMetalorganic vapor phase epitaxy is a complicated process whereby constituents of incoming reactant species are incorporated into the growing crystal through a number of stages. A range of optical probes has been developed to provide detailed information about these stages and the sample as growth proceeds. While many of these probes are mature, spectroscopic ellipsometry (SE) and polarimetry (SP) are both undergoing rapid improvements as a result of applications in integrated‐circuits technology. Here, I review some of these advances and the motivation behind them, and illustrate capabilities with an application regarding the heteroepitaxial growth of GaSb on GaAs. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of indium nanowires – an adsorption study
Authors: Fleischer K. , Chandola S. , Esser N. , McGilp J. F. 
Published: September 2005

AbstractChanges in the optical anisotropy of the Si(111)‐In:(4 × 1) surface and its low temperature (8 × 2) phase upon adsorption of additional indium and caesium were monitored by reflectance anisotropy spectroscopy. It is shown that, at submonolayer coverages, characteristic changes in the optical anisotropy occur, which are independent of the type of adsorbate and are correlated with the disappearance of the phase transition. The behaviour is shown to be consistent with the model that charge density wave formation occurs at the transition temperature. The optical anisotropy of the chains is measured in the near infrared regime and discussed in terms of interband transitions and anisotropic conductance. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum phase transitions and superconductivity: Proposal for the phase diagram of alkali‐doped fullerides and by universality HTSC including Wigner solids
Authors: Squire Richard H. , March Norman H. 
Published: September 2005

AbstractThe present study has two prime aims. The first is to attempt an explanation of the recent experiment on a high Tc cuprate in which the superconductivity is suppressed by an applied magnetic field of 58 tesla (T). We propose an interpretation in terms of a specific quantum transition, namely a magnetically induced Wigner solid of charge carriers. Second, we explore similarities between superconductivity in alkali‐doped fullerides and the high Tc cuprates based on an interpretation of Uemura‐type plots. A phase diagram for alkali‐doped fullerides is proposed that contains possible universal quantum phase transitions. Evidence is presented that suggests the superconducting phase is located between Wigner solids of charge carriers in fullerides at higher and lower doping at T = 0. Implications are discussed. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Experimental and theoretical studies of the interaction of silver cluster cations Ag (n = 1–4) with ethylene
Authors: Tian Zhixin , Tang Zichao 
Published: September 2005

AbstractReactions of silver cluster cations Ag with ethylene have been studied using a reflectron time‐of‐flight mass spectrometer. Chemisorbed Agn(C2H4) (n = 1–3, m = 1–6) complexes were observed. For a given value of n, the abundances of Agn(C2H4) (n = 1–3, m = 1–6) species first increase and then decrease, with the maximum of the intensity distribution usually at m = 4. This maximum does not change with the ethylene concentration in the mixed gas, the stagnation pressure of the mixed gas, or the size of Ag (n = 1–3). A complementary extensive theoretical study on the structure and binding of Agn(C2H4) (n = 1–4, m = 1–4) is also reported. Preferred binding sites, binding energies, geometries, vibrational frequencies, and ionization potentials are determined using density functional theory. Copyright © 2005 John Wiley & Sons, Ltd.
Determination of adefovir in human plasma by liquid chromatography/tandem mass spectrometry: application to a pharmacokinetic study
Authors: Bi Hui‐chang , Zhong Guo‐ping , Zhou Shufeng , Chen Xiao , Huang Min 
Published: September 2005

AbstractA liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed and validated to determine the concentrations of adefovir [9‐(2‐phosphonylmethoxyethyl)adenine, PMEA] in human plasma. After one‐step protein precipitation of plasma samples by methanol, adefovir was analyzed by LC/MS/MS using positive electrospray ionization. Chromatography was performed on a C18 column. The extraction recoveries of adefovir were found to be 85.1–89.3%. Adefovir was stable under routine laboratory conditions. A minimal matrix effect resulting in a slight ionization enhancement of adefovir (<10.9%) was observed, which did not markedly affect the behavior of the calibrations curves and accuracy and precision data. The method had a chromatographic run time of 7.8 min and a linear calibration curve over the concentration range 1.5–90 ng/mL for adefovir. The lower limit of quantification of the method was 1.5 ng/mL. The intra‐ and inter‐day precision was less than 8.4%. These results indicated that this LC/MS/MS method has high selectivity and efficiency, and acceptable accuracy, precision and sensitivity. The validated LC/MS/MS method has been successfully used in a pharmacokinetic study in healthy volunteers treated with oral adefovir dipivoxil at 10 and 20 mg. Copyright © 2005 John Wiley & Sons, Ltd.
Social behaviour in an Australian velvet worm, Euperipatoides rowelli (Onychophora: Peripatopsidae)
Authors: Reinhard Judith , Rowell David M. 
Published: September 2005

AbstractOnychophora lead a cryptic lifestyle as predators in decaying logs and leaf litter. Hence, very little is known about their behaviour. They are generally assumed to possess only a limited behavioural repertoire, even though their surprisingly evolved brain suggests otherwise. Our studies on the Australian species Euperipatoides rowelli show for the first time that onychophorans are indeed capable of complex behaviour. Euperipatoides rowelli individuals form aggregations of up to 15 females, males and young. These aggregations are not random assemblages, but close social groups organized in a hierarchy based on female dominance. Food is hunted collectively, but the dominant female of a group feeds alone, before other females, males and young. Hierarchy within a group is established by aggressive‐dominant and passive‐subordinate behaviours, the latter leading to tolerance of body contact and aggregation. Euperipatoides rowelli from foreign groups, i.e. from different logs, are met with intense aggression, and individuals rarely aggregate. The reasons for this aggression are not clear, but we suggest that its origins lie in kin recognition. The evolution of social behaviour within the Onychophora is discussed with respect to their ecology, population genetics and phylogeny.
Life‐history traits and sexual dimorphism of the Atlantic forest maned sloth Bradypus torquatus (Xenarthra: Bradypodidae)
Authors: Lara‐Ruiz Paula , Chiarello Adriano Garcia 
Published: September 2005

AbstractThis work presents new data from 48 maned sloths Bradypus torquatus captured between November 2002 and November 2003 in three regions of the Atlantic forest where the largest remnant populations of this species are found. Data from another long‐term study, carried out from 1994 to 1996 and from 1999 to the present (n=14), were also used, making a total sample of 62 sloths. Average adult body weight is 6594±236 g and average head‐body length is 66.5±0.8 cm (n=35), indicating that Bradypus torquatus is the heaviest of all four Bradypus species. Individuals from lower‐montane forests (600–1000 m a.s.l.) are significantly larger (head–body length; t‐test; P=0.001) than individuals from the lowlands (<350 m a.s.l.), suggesting altitudinal differentiation between populations. Sexual dimorphism, here reported for the first time, was found in body length (females are significantly larger than males) and in other external characters, such as mane size and form (darker and larger in males), and size and shape of the external genitalia. Most differences between sexes are, however, only discernible in reproductively active individuals. Breeding is slightly seasonal; minimum observed interbirth interval was 1 year and litter size was always one. Infants stayed with their mothers until 8–11 months old; started feeding on solid food as early as 2 weeks old but continued suckling until c. 4 months of age. Age of sexual maturity was estimated at 2–3 years and the oldest captured maned sloth was a healthy male who was at least 12 years of age. Overall, results indicated that maned sloths are similar in these aspects to congeneric species. Information presented here significantly improves the current knowledge on this endangered sloth species and is useful for the proper planning and implementation of in situ conservation strategies such as translocations and reintroductions.
Do solitary, seismic signalling Cape mole‐rats (Georychus capensis) demonstrate spontaneous or induced ovulation?
Authors: van Sandwyk James H. d. T. , Bennett Nigel C. 
Published: September 2005

AbstractThe Cape mole‐rat Georychus capensis is a solitary subterranean rodent that exhibits seasonal reproduction. This study set out to determine whether the female Cape mole‐rat is an induced or spontaneous ovulator. Eleven females were collected from the field just before the breeding season and housed individually. Urine was collected for 5 weeks. Females were subjected to one of three trials: housed separately without a male; allowed only non‐physical contact with unvasectomized males; placed in direct contact with four vasectomized males. Urine was collected for a further 5 weeks and urinary progesterone profiles established. Females housed in direct contact with males exhibited heightened progesterone concentrations and the presence of corpora lutea in their ovaries. The act of coitus seems to be necessary for ovulation to occur in the females even though males were not capable of fertilization.
The predatory impact of the freshwater invader Dikerogammarus villosus on native Gammarus pulex (Crustacea: Amphipoda); influences of differential microdistribution and food resources
Authors: MacNeil Calum , Platvoet Dirk 
Published: September 2005

AbstractPredation between invading and native species can produce patterns of exclusion and coexistence. Dikerogammarus villosus, a Ponto‐Caspian amphipod species, has invaded many central European freshwaters in the past decade, replacing native Gammarus amphipod species. For instance, the arrival of D. villosus in Holland has been accompanied by the decline of Gammarus duebeni and G. tigrinus populations within invaded systems. This study examined what may happen when D. villosus eventually encounters native Dutch populations of Gammarus pulex, and how factors such as microhabitat and food resource availability could contribute to a future species replacement or coexistence. A laboratory simulation of a lake/pooled area of river indicated that G. pulex and D. villosus differed in distribution within the same habitat, and showed that although the distribution of the native differed in the presence of the invader, the presence of the native had no effect on the distribution of the invader. Gammarus pulex suffered severe intraguild predation (IGP) from D. villosus in mixed species treatments with no reciprocal predation of D. villosus by G. pulex. This IGP occurred regardless of whether no alternative food resource was available (91% of the G. pulex population eliminated after 7 days), or alternative foods/prey were available to excess, such as leaf material (85%), chironomids (77%) or fish food flakes (74%). We conclude that although differential microdistribution of the two species could promote coexistence, the presence of alternative foods/prey resources, merely slow the rate of IGP and replacement of the native by the invader. Our study joins one of an increasing number emphasizing the potential damaging impacts of D. villosus on native communities.
Melatonin‐evoked potentiation of the juvenile rat tail artery neurogenic reactivity depends on degree of the change in the reactivity
Authors: Karachentseva O. V. , Yartsev V. N. , Dvoretsky D. P. , Zhdanova I. V. 
Published: September 2005

AbstractAim:  Dependence of the melatonin‐evoked potentiation of the rat tail artery neurogenic reactivity on degree of the change in the reactivity was studied.Method:  Electrical field stimulation‐evoked contractile response of the juvenile rat tail artery segment under isometric conditions was recorded. 0.1 μm melatonin was administered after the change in the response produced both spontaneously and by acidification (pH 6.6) or alkalinization (pH 7.8) of the solution.Results:  During the course of experiment, the contraction force continuously declined, being reduced by 12 ± 5, 24 ± 7 and 32 ± 6% at 20, 70, and 170 min after beginning of experiment, respectively. Melatonin applied at these time points increased the contraction by 20 ± 5, 41 ± 10, and 48 ± 8%, respectively, relative to control. This increase in potentiating effect of melatonin during the course of experiment was not because of sensitization of the segment to the hormone. Acidosis‐induced considerable decline in neurogenic contraction was counteracted by melatonin, while after alkalosis‐induced augmentation in the contraction the hormone was not effective. Melatonin increased the artery response to 0.1 μm noradrenaline.Conclusion:  These data suggest that melatonin can restore an attenuated neurogenic reactivity of the juvenile rat tail artery. The effect is more pronounced with further decrease in reactivity and might be due to a change in sensitivity of the post‐junctional membrane to noradrenaline.
Relaxant effects of β‐adrenergic agonists on porcine and human detrusor muscle
Authors: Badawi J. K. , Uecelehan H. , Hatzinger M. , Michel M. S. , Haferkamp A. , Bross S. 
Published: September 2005

AbstractAim:  Relaxant effects of different β‐adrenoceptor agonists on porcine and human detrusor were examined. Thus, the β‐adrenoceptor subtype mainly responsible for relaxation in the detrusor muscle of pigs was characterized. Additionally, different effects of several β‐agonists in both species were shown.Methods:  Experiments were performed on muscle strips of porcine and human detrusor suspended in a tissue bath. The relaxant effects of the non‐selective β‐agonist isoprenaline, the selective β2‐agonists procaterol, salbutamol and the selective β3‐agonists BRL 37344, CL 316 243 and CGP 12177 on potassium‐induced contraction were investigated. The inhibitory effect of different substances on the maximum contraction and the rank order of potency for endogenous catecholamines was determined in pigs. Furthermore, concentration‐relaxation curves were performed for pigs and humans.Results:  Pigs: In the pre‐treatment experiments isoprenaline and procaterol showed similar effects. The concentration–response experiments showed that the maximum relaxation induced by procaterol and salbutamol was more than 90%, not significantly different from isoprenaline, whereas the maximum relaxations of CL 316 243, BRL 37344 and CGP 12177 amounted to 68, 70 or 30%, respectively. Rank order of potencies was isoprenaline ≥ adrenaline > noradrenaline. Humans: Isoprenaline, procaterol, salbutamol and CL 316 243 showed a maximum relaxation of 80, 41, 24 and 35% and pD2 values of 6.24, 5.65, 5.48 and 5.55, respectively.Conclusion:  β2‐receptors play a main functional role in mediating relaxation of porcine detrusor. Selective β2‐ and β3‐agonists similarly relax the human detrusor. Effects were smaller compared with the pig.
Exhaled nitric oxide during normoxic and hypoxic exercise in endurance athletes
Authors: Verges S. , Flore P. , Favre‐Juvin A. , Lévy P. , Wuyam B. 
Published: September 2005

AbstractAim:  Endogenous nitric oxide (NO) through its relaxing effect on smooth muscle cells may be involved in pulmonary gas exchange as well as in the modulation of the hypoxic pulmonary vasoconstriction. As athletes with exercise‐induced hypoxaemia (EIH) present pulmonary gas exchange abnormalities in normoxia that could be even greater in hypoxia, we hypothesized that pulmonary NO may be lower in such athletes with EIH.Methods:  Eleven athletes with EIH [decrease in arterial oxygen blood partial pressure (PaO2) > 12 mmHg] and 9 without EIH (NEIH) exercised at 40%, 60% (10 min) and 90% (5 min) of normoxic maximal power output (Pmax) in normoxia, and at 40% and 60% (10 min) of Pmax in hypoxia (FiO2 = 15%). Exhaled NO concentration during a constant flow exhalation (FENO0.170) and arterialized blood gases were measured at every power output.Results:  FENO0.170 decreased from rest to exercise both in normoxia (−27.8 ± 22.8% at 90%Pmax, P < 0.001) and hypoxia (−23.8 ± 17.5% at 60%Pmax, P < 0.001). At 90%Pmax in normoxia, EIH athletes showed lower PaO2 (76.7 ± 5.4 vs. 82.8 ± 4.4 mmHg, P = 0.013) and greater FENO0.170 decrement (−37.0 ± 24.7% vs. −16.6 ± 14.6%, P = 0.042) than NEIH athletes. During hypoxic exercise, PaO2 and FENO0.170 decreases were similar in both groups (P > 0.05).Conclusion:  The present study shows lower pulmonary NO in athletes with gas exchange abnormalities during intense exercise in normoxia, while EIH and NEIH athletes have similar decreases in blood gases and pulmonary NO during hypoxic exercise. Decreased pulmonary NO in such conditions may contribute to ventilation‐perfusion inequality and/or increase pulmonary vascular tone in athletes.
Effect of breathing low concentrations of volatile anaesthetic agents on incidence of adverse airway events
Authors: Goodwin N. , Strong P. J. , Sudhir G. , Wilkes A. R. , Hall J. E. 
Published: September 2005

SummaryThe effect of breathing 0.1 minimum alveolar concentrations (MAC) of desflurane or isoflurane for three minutes on the incidence of adverse airway events on a subsequent breath of 2 MAC was investigated. Twenty‐five volunteers known to develop an adverse airway event to desflurane or isoflurane took part in the study. Each volunteer was exposed to isoflurane and desflurane at least 24 h apart. Volunteers were assessed for adverse airway events while breathing 2 MAC inhalational anaesthetic following breathing 100% O2 for 3 min. This was repeated with 0.1 MAC inhalational anaesthetic in oxygen instead of 100% O2. Adverse airway events decreased from 88% to 40% when tests were conducted with desflurane (p = 0.002). With isoflurane, the reduction from 60% to 52% was not statistically significant (p = 0.774). Breathing low concentrations of desflurane decreases the incidence of adverse airway events on subsequent inhalation of higher concentration of desflurane.
Cardiac output measurement by pulse dye densitometry in cardiac surgery
Authors: Baulig W. , Bernhard E. O. , Bettex D. , Schmidlin D. , Schmid E. R. 
Published: September 2005

SummaryThe aim of this study was to compare the accuracy of pulse dye densitometry with that of bolus thermodilution cardiac output measurement in patients before and after elective coronary artery bypass grafting. Twenty‐eight patients were studied. Agreement between mean thermodilution and pulse dye densitometry cardiac output values was assessed by Bland‐Altman analysis. Preoperative median [range] cardiac output was 3.87 [2.37–6.0] l.min−1 by thermodilution, and 3.11 [1.7–5.45] l.min−1 by pulse dye densitometry using indocyanine green 5 mg. Pulse dye densitometry underestimated cardiac output (mean bias − 0.42 l.min−1); the limits of agreement were ± 1.91 l.min−1, and mean error was 50.3%, indicating low precision. Preoperative median [range] cardiac output was 3.85 [2.2–6.0] l.min−1 for bolus thermodilution cardiac output and 4.2 [2.0–7.2] l.min−1 for pulse dye densitometry using indocyanine green 20 mg. Mean bias was + 0.566 l.min−1, the limits of agreement were ± 2.51 l.min−1 and mean error was 60.9%. Postoperative cardiac output data were not analysed because pulse dye densitometry signals were low or absent in > 50% of the patients. We conclude that pulse dye densitometry using indocyanine green 5 mg or 20 mg is inaccurate in anaesthetised patients before coronary artery bypass surgery and cannot be used after surgery because of a high incidence of low pulse dye densitometry signal amplitudes.