bluuebunny/crossref_metadata_2025 huggingface dataset:
A case of Behcet's disease with pulmonary artery aneurysm and thrombosis
Authors: Ilvan Ahmet , Okutan Oguzhan , Kartaloglu Zafer , Ciftci Faruk , Kizilkaya Esref , Silit Emir , Kutlu Ali
Published: May 2005

A 22 year old patient with dyspnea, cough, chest pain, fatigue, mild fever and swelling of the lower extremities was hospitalized. Physical examination revealed bilateral decrease in respiratory sounds and end-inspiratory fine rales at the left posterobasal area. Circumferences of both legs were increased. During hospitalization period, oral aphthous and scrotal ulceration were appeared. Bilateral multiple peripheral and central pulmonary artery aneurysms at middle zones were found with dynamic computerized tomography of thorax and magnetic resonance angiography of the lungs. Patient was diagnosed as Behcet's disease with lung involvement. Magnetic resonance angiography performed at the sixth month of the treatment revealed a significant regression in aneurysmatic changes, whereas a right ventricular thrombosis had been developed.
Knotting of intracardiac flow-directed balloon catheter: A non-surgical technique for removal
Authors: Kinay Ozan , Ozaydin Mehmet , Okutan Hüseyin , Kahraman Halil , Nazli Cem , Altinbas Ahmet , Ergene Oktay
Published: May 2005

A knot occurred in a flow-directed balloon tipped (Swan-Ganz) catheter inserted through the right internal jugulary vein. Knot was undone using right Judkins catheter introduced via left jugulary vein approach. By passing through the loop of knot, right Judkins catheter was used to stabilize the knotted segment and knot was unknotted by gently pulling the Swan-Ganz Catheter.
Discrete type subaortic stenosis in dextrocardia with situs inversus totalis
Authors: Korkut Bayram , Altinbaş Ahmet , Sarigüzel Asm , Özergin Ufuk , Gök Hasan
Published: May 2005

This paper presents the case report of a patient with discrete type subaortic stenosis in dextrocardia and its associated clinical manifestations.
Spontaneous splenic rupture complicating thrombolytic therapy in acute myocardial infarction
Authors: Enar Rasim , Pehlivanoğlu Seçkin , Ersanli Murat , Baltay Ayhan , Çeliker Cengiz , Yazicioğlu Nuran
Published: May 2005

A 64-year-old woman with the diagnosis of acute anterior infarction was treated with streptokinase, i.v. heparin, and aspirin. After 20 hours of hospitalization she developed hypotension and a fall in hematocrit level with acute onset of severe abdominal pain. After genitourinary and gastrointestinal bleeding, pulmonary embolism and reinfarction had been ruled out, however, abdominal ultrasonography revealed intraabdominal hemorrhage and the patient was given three units of blood transfusion. Abdominal laparotomy and laparoscopy were not performed as the patient's clinical status stabilized on the 3rd day and hemodynamics did not deteriorate thereafter. Abdominal computerized tomography in the second week revealed a splenic rupture.
Surgery for three-channeled aortic dissection
Authors: Ando Motomi , Takamoto Shinichi , Okita Yutaka , Moroto Tetsuro
Published: May 2005

Among aortic dissections, three-channeled aortic dissection, in which two parallel false lumens are present, is relatively rare. We surgically treated 26 patients with this type of dissection, they accounted for 7.4% of all 349 patients with aortic dissection surgically treated between 1978 and May 1997. Their ages ranged from 24 to 77 years (mean 45 years). The male/female ratio was 1:1. Marfan's syndrome was present in 15 patients and Bentall's-type operation had been performed in 12 patients. Pain at different times was observed in 19 patients. For preoperative diagnosis, computed tomography (CT) and magnetic resonance imaging (MRI) were useful. The morphology of the 1st and 2nd false lumens was Stanford type A + type B in 11 patients, type B + type B in 12, type A + type A in 2, and localized abdominal dissection in 1. Reentry of the second false lumen was observed in only 3 patients. Descending aortic replacement was performed in 13 patients, thoracoabdominal aortic replacement in 6, ascending aortic replacement in 3, and others in 4. Seven patients died in the hospital. There were 4 late deaths during follow-up for 10–158 months (mean, 58 months). When pain recurred in patients with aortic dissection, three-channeled dissection should be suspected. The incidence of this dissection is high in patients with Marfan's syndrome.
Brief report: The ego identity process questionnaire: Factor structure, reliability, and convergent validity in Dutch‐speaking late adolescents
Authors: Luyckx Koen , Goossens Luc , Beyers Wim , Soenens Bart
Published: May 2005

The reliability and validity of a Dutch version of the Ego Identity Process Questionnaire (EIPQ) were evaluated. In Study 1, the instrument was found to exhibit a clear factor structure and acceptable reliability. Using Confirmatory Factor Analysis, both a model with two process factors (Commitment, Exploration) and a model with four content factors (Ideological Commitment, Ideological Exploration, Interpersonal Commitment, Interpersonal Exploration) evidenced a good fit once direction of wording was taken into account. In Study 2, moderate convergence was observed between Commitment and Exploration, and continuous measures of identity statuses and identity styles. The results of both studies combined indicated that the Dutch version of the EIPQ may be recommended as a research tool with college students.
17‐β‐Estradiol activates maxi‐K channels through a non‐genomic pathway in human breast cancer cells
Authors: Coiret Guyllaume , Matifat Fabrice , Hague Frédéric , Ouadid-Ahidouch Halima
Published: May 2005

We have investigated the acute effects of 17‐β‐estradiol (E2) on K+ channels in MCF‐7 breast epithelial cancer cells. E2 induced a rapid and irreversible augmentation of the K+ current for all membrane potentials superior to −25 mV. The effect of E2 was sensitive to Iberiotoxin, Charybdotoxin and TEA and can be elicited in the presence of the anti‐estrogen ICI 182 780 or be mimicked by the membrane impermeant form E2/BSA. Furthermore, E2/BSA was able to stimulate cell proliferation in a maxi‐K inhibitors‐sensitive manner. Thus, these results permit us to identify the maxi‐K channel as the molecular target of E2 that regulates cell proliferation independently of the estrogen receptor.
A putative novel alpha/beta hydrolase ORFan family in Bacillus
Authors: Siew Naomi , Saini Harpreet Kaur , Fischer Daniel
Published: May 2005

A large number of sequences in each newly sequenced genome correspond to lineage and species‐specific proteins, also known as ORFans. Amongst these ORFans, a large number are sequences with unknown structures and functions. We have identified a family of sequences, annotated as hypothetical proteins, which are specific to Bacillus and have carried out a computational study aimed at characterizing this family. Fold‐recognition methods predict that these sequences belong to the α/β hydrolase fold. We suggest possible catalytic triads for the ORFans and propose a hypothesis regarding the possible families within the α/β hydrolase superfamily to which they may belong.
Catalytic residues and substrate specificity of scytalidoglutamic peptidase, the first member of the eqolisin in family (G1) of peptidases
Authors: Kataoka Yukiko , Takada Katsumi , Oyama Hiroshi , Tsunemi Masahiko , James Michael N.G. , Oda Kohei
Published: May 2005

Scytalidoglutamic peptidase (SGP) is the first‐discovered member of the eqolisin family of peptidases with a unique structure and a presumed novel catalytic dyad (E136 and Q53) [Fujinaga et al., PNAS 101 (2004) 3364–3369]. Mutants of SGP, E136A, Q53A, and Q53E lost both the autoprocessing and enzymatic activities of the wild‐type enzyme. Coupled with the results from the structural analysis of SGP, Glu136 and Gln53 were identified as the catalytic residues. The substrate specificity of SGP is unique, particularly, in the preference at the P3 (basic amino acid), (small a.a.), and (basic a.a.) positions. Superior substrates and inhibitors have been synthesized for kinetic studies based on the results reported here. k
cat, K
m, and k
cat/K
m of SGP for d‐Dap(MeNHBz)‐GFKFF*ALRK(Dnp)‐d‐R‐d‐R were 34.8 s−1, 0.065 μM, and 535 μM−1
s−1, respectively. K
i of Ac‐FKF‐(3S,4S)‐phenylstatinyl‐LR‐NH2 for SGP was 1.2 × 10−10
M. Taken together, we can conclude that SGP has not only structural and catalytic novelties but also a unique subsite structure.
Identification of B cell adaptor for PI3‐kinase (BCAP) as an Abl interactor 1‐regulated substrate of Abl kinases
Authors: Maruoka Masahiro , Suzuki Jun , Kawata Shigehisa , Yoshida Kayo , Hirao Noriko , Sato Seiichi , Goff Stephen P. , Takeya Tatsuo , Tani Katsuko , Shishido Tomoyuki
Published: May 2005

In previous work we showed that Abl interactor 1 (Abi‐1), by linking enzyme and substrate, promotes the phosphorylation of Mammalian Enabled (Mena) by c‐Abl. To determine whether this mechanism extends to other c‐Abl substrates, we used the yeast two‐hybrid system to search for proteins that interact with Abi‐1. By screening a human leukocyte cDNA library, we identified BCAP (B‐cell adaptor for phosphoinositide 3‐kinase) as another Abi‐1‐interacting protein. Binding experiments revealed that the SH3 domain of Abi‐1 and the C‐terminal polyproline structure of BCAP are involved in interactions between the two. In cultured cells, Abi‐1 promoted phosphorylation of BCAP not only by c‐Abl but also by v‐Abl. The phosphorylation sites of BCAP by c‐Abl were mapped to five tyrosine residues in the C‐terminal region that are well conserved in mammals. These results show that Abi‐1 promotes Abl‐mediated BCAP phosphorylation and suggest that Abi‐1 in general coordinates kinase‐substrate interactions.
Photothermal studies of CO photodissociation from mixed valence Escherichia coli cytochrome bo3
Authors: Mikšovská Jaroslava , Gennis Robert B. , Larsen Randy W.
Published: May 2005

Here, we report the volume and enthalpy changes accompanying CO photodissociation from the mixed valence form of cytochrome bo
3 oxidase from Escherichia coli. The results of photoacoustic calorimetry indicate two kinetic phases with distinct volume and enthalpy changes accompanying CO photodissociation from heme o
3 and its transfer to CuB. The first phase occurring on a timescale of <50 ns is characterized by a volume decrease of −1.3 ± 0.3 mL mol−1 and enthalpy change of 32 ± 1.6 kcal mol−1. Subsequently, a volume increase of 2.9 mL mol−1 with an enthalpy change of −5.3 ± 2.5 kcal mol−1 is observed with the lifetime of ∼250 ns (this phase has not been detected in previous optical studies). These volume and enthalpy changes differ from the volume and enthalpy changes observed for CO dissociation from fully reduced cytochrome bo
3 oxidase indicating that the heme o
3/CuB active site dynamics are affected by the redox state of heme b.
Phosphorylation of a tyrosine at the N‐terminus regulates the surface expression of GIRK5 homomultimers
Authors: Mora S. Ivonne , Escobar Laura I.
Published: May 2005

The G protein‐coupled inwardly rectifying GIRK5 and Δ5GIRK5 splicing variants do not express functional potassium channels. In contrast, Δ25GIRK5 forms functional homomultimers in Xenopus laevis oocytes. A tyrosine is present at the N‐term of the non‐functional isoforms. We studied the effect of endogenous tyrosine phosphorylation on the GIRK5 surface and functional expression. Unlike wild type channels, GIRK5Y16A and Δ5GIRK5Y16A mutants displayed inwardly rectifying currents and inhibitors of Src tyrosine kinase promoted the traffiking of GIRK5 to the cell surface. This is the first evidence that endogenous phosphorylation of a tyrosine residue in a GIRK channel inhibits its surface expression.
Mechanisms for HIV Tat upregulation of IL‐10 and other cytokine expression: Kinase signaling and PKR‐mediated immune response
Authors: Li James C.B. , Lee Davy C.W. , Cheung Benny K.W. , Lau Allan S.Y.
Published: May 2005

HIV Tat has been known to have multiple regulatory roles including replication of HIV and modulation of cellular kinases. We investigated whether signaling kinase PKR plays a critical role in mediating Tat‐induced cytokine dysregulation. We showed Tat induction of IL‐10 dysregulation is associated with PKR activation. To examine the mechanism involved, inhibition of PKR activity abrogated the Tat‐induced cytokine induction. We next identified that the MAP kinases including ERK‐1/2 and p38 are downstream of PKR in these Tat‐induced pathways. Thus, PKR may play a critical role in mediating the subversive effects of HIV Tat resulting in IL‐10 induction.
CysMap and CysJoin: Database and tools for protein disulphides localisation
Authors: Caporale Carlo , Bertini Laura , Pucci Piero , Buonocore Vincenzo , Caruso Carla
Published: May 2005

We have developed a computer program able to make user‐customised databases derived from the public PIR non‐redundant reference protein database. When the database of interest has been created, the user will generate the map of all the possible linear peptides containing one and two cysteines for each protein and combine them to calculate the mass of all the possible clusters of linear peptides linked by a disulphide bridge with a cysteine pair. It is also possible to create selected maps corresponding to peptides formed by the action of specific proteases. In this way, mass spectrometric data obtained from the hydrolysis of proteins of unknown sequence can be related to that contained in the database for quick disulphide assignment and protein identification. To confirm signal attribution, the program will also furnish the expected mass of cluster peptides after performing a cycle of Edman degradation. The utility of the program is discussed and examples of application are given.
Signaling pathways involved in tumor necrosis factor α‐induced upregulation of the taurine transporter in Caco‐2 cells
Authors: Mochizuki Tetsunosuke , Satsu Hideo , Shimizu Makoto
Published: May 2005

We have previously demonstrated that the taurine uptake and transporter (TAUT) mRNA expression were upregulated by tumor necrosis factor α (TNF‐α) in Caco‐2 cells. In this present study, the signaling molecules related to this upregulation were investigated. Pyrrolidine dithiocarbamate, a nuclear factor κB (NF‐κB) inhibitor, repressed the upregulation of taurine uptake and TAUT mRNA expression. A reporter assay revealed that TNF‐α‐induced TAUT transcriptional activity through the NF‐κB consensus‐like sequence in the human TAUT promoter region. An electrophoretic mobility shift assay showed that NF‐κB could bind to the NF‐κB consensus‐like sequence. The anti‐TNF receptor 1 (TNFR1) antibody, but not the TNF receptor 2 (TNFR2) antibody, repressed this upregulation.
Chela-height vs. body-weight relationships for North Sea hermit crabs (Paguridae)
Authors: Reiss Henning , Neumann Hermann , Kröncke Ingrid
Published: May 2005

Biomass determination of hermit crabs is difficult without destroying the gastropod shells of the specimens. To minimize the number of animals destroyed in the process of determining this parameter over time, the chela-height vs. body-weight relationship of each of the three hermit-crab species was recorded in different areas of the North Sea. Linear regression was carried out for the species Pagurus bernhardus, P. pubescens, and P. prideauxi, in order to allow calculations of individual biomass on the basis of the chela height of specimens. No spatial differences in the chela-height vs. body-weight relationship were found for single species, whereas the relationship between the three species differed significantly. Thus, for each species a regression function is given, valid for the whole North Sea, that allows estimations of the body weight of the three hermit-crab species from measuring the chela height alone.
Variations in the distributions of Centropages chierchiae and Temora stylifera (Copepoda: Calanoida) in the north-eastern Atlantic Ocean and western European shelf waters
Authors: Lindley J.A. , Daykin S.
Published: May 2005

Centropages chierchiae and Temora stylifera occurred rarely in the Continuous Plankton Recorder (CPR) survey in the Bay of Biscay, Celtic Sea, and English Channel before 1988. By 2000 they were found frequently and in abundance. The seasonal cycles of abundance of these species differ, C. chierchiae occurring mainly in the summer while T. stylifera was found most frequently in late autumn or winter towards the northern limits of its distribution. The increase in abundance of both species is related to temperature. However, in the years when it was found in the samples, the frequency of occurrence of C. chierchiae was correlated positively with the strength of the shelf edge current and negatively with the North Atlantic Oscillation (NAO) while the reverse was true for T. stylifera.
Petrology and potential tectonic significance of a K-bentonite in a Taconian shale basin (eastern Ontario, Canada), northern Appalachians
Authors: SHARMA SAJAL , DIX GEORGE R. , VILLENEUVE MIKE
Published: May 2005

A 6 cm thick K-bentonite, herein defined as the Russell Bed, occurs in an Upper Ordovician deep-basin shale succession in eastern Ontario, Canada, forming part of the distal Taconic foreland in eastern North America. The bed lies within the pygmaeus graptolite Biozone, which is about 451 to 452 Ma in age. Although some bentonites are reported from this interval in eastern North America, we are reporting the first set of compositional data for a bentonite of this age. Gamma-log correlation identifies a potential minimum distribution area of <2×105 km2 for the K-bentonite, covering part of southern Quebec, New York State and eastern Ontario. The deposit coincides with the first influx of distal turbdites into this shale basin, associated with Taconic flysch, and simultaneous abrupt ventilation of the once anoxic deep-water basin, which had formed initially after foundering of the Upper Ordovician carbonate platform. Concurrent intrabasinal extinction of several graptolite species suggests that change in sedimentation, palaeoceanography and volcanism were linked to a regional external process. Compositionally, the bentonite is distinct from the older Ordovician platform deposits in eastern North America. The deposit contains abundant titaniferous phlogopite with 1.6% BaO, fluoroapatite with 2.5% F, and dynamically shaped glass spherules now altered to clay. The spherules and clay matrix constitute 45% of the bed and, compositionally, define an illite (>90%)–smectite (I/S) structure with about 7.5% K2O%. Age-dating by Ar–Ar analysis of the phlogopite crystals yielded a younger than expected (440–445 Ma) age. This difference, along with evidence of localized chloritization of phlogopite, likely reflects known post-Ordovician hydrothermal activity within the basin. On the basis of several geochemical proxies, the magmatic source of the Russell K-bentonite falls within the trachyandesite field and was Ba-enriched. Comparison of geochemistry and mineralogy with older, Middle to Late Ordovician and younger Early Silurian K-bentonites within the Taconic orogen along eastern Laurentia and Baltica reveals that the potential source magma for the Russell Bed was more mafic, more alkaline, and less fractionated than sources typical of older (platform) bentonites. Instead, it is more similar to the younger Llandovery bentonites of Scandinavia and Scotland. It remains uncertain if it signals local or regional compositional change in volcanic source in the northern Appalachians.
An articulated phyllolepid fish (Placodermi) from the Devonian of central Australia: implications for non-marine connections with the Old Red Sandstone continent
Authors: YOUNG GAVIN C.
Published: May 2005

A second species of the placoderm genus Placolepis (Pl. harajica sp. nov.), based on a single articulated specimen from Givetian–Frasnian strata in the MacDonnell Ranges, demonstrates the occurrence of this taxon across the Australian craton. Placolepis (order Phyllolepida) is endemic to east Gondwana, and other phyllolepids are widespread in the Givetian and younger of Gondwana (Australia, Antarctica, Turkey, Venezuela), but do not occur until Late Devonian (Famennian) time in the Northern Hemisphere (Europe, Russia, Greenland, North America). The disjunct space–time distribution of the Phyllolepida is inconsistent with palaeomagnetic evidence indicating a wide equatorial ocean between Gondwana and Laurussia in Late Devonian time. This new species provides additional evidence supporting a Gondwana origin for the group, and later access to northern landmasses resulting from closure of the ocean between Gondwana and Laurussia and continental connection at or near the Frasnian–Famennian boundary.
On the variability of dissolved oxygen and apparent oxygen utilization content for the upper world ocean: 1955 to 1998
Authors: Garcia Hernan E. , Boyer Tim P. , Levitus Sydney , Locarnini Ricardo A. , Antonov John
Published: May 2005

We document variability in O2, AOU, and heat content in the top 100 m of the world ocean (70°S–70°N) between 1955 and 1998 using observational data. The lowest O2 (highest AOU) content in the late‐1950s are followed by high content in the mid‐1980s and by low content in the late‐1990s. The O2 and AOU content variability is characterized by relatively small linear trends superimposed on large decadal‐scale fluctuations. The largest O2 content changes occur in the Northern Hemisphere (NH). The NH exhibits a negative linear trend in O2 content of ∼−30 Tmol per decade between 1983 and 1998 and a positive linear trend of ∼6 Tmol per decade between 1955 and 1998 (1 Tmol = 1012 mol). The trends in O2, AOU, and heat content are sensitive to the time frame of the measurements. The results indicate that a constant upper‐ocean O2 content inventory should not be assumed on decadal time‐scales.
Airborne measurements of aerosol, ozone, and solar ultraviolet irradiance in the troposphere
Authors: Varotsos Costas
Published: May 2005

Measurements of the distributions of the aerosol characteristics and solar ultraviolet irradiance were conducted by using instrumentation flown on a Falcon aircraft over the entire Greek area from the sea up to the middle troposphere. To study the impact of the aerosol abundance to the solar ultraviolet irradiance at various altitudes, complementary observations of ozone concentration, relative humidity, and temperature have been also performed using instrumentation flown on free balloons. In addition to a detailed description of the observed aerosol characteristics we attempt an improvement of the earlier proposed theoretical algorithms regarding the absolute values of the solar ultraviolet irradiance at various tropospheric altitudes. This is achieved by taking into account the measured accumulation aerosol particle and cloud droplet size distributions. The measurements showed that a double‐layer structure in the vertical distribution of the number density of the cloud droplets and particle size aerosol was prevalent. In particular, over the area west of Crete the aerosol particles possessed a bimodal size distribution with mean diameters of 0.11 and 0.225 μm. Moreover, upon using the obtained aerosol distribution data in the radiative transfer calculations, we find that the calculated values of the solar ultraviolet irradiance correlate well with the observed ones, showing an 4.3 ± 0.1% km−1 increase for altitudes ranging from the ground to 6.2 km.
Direction finding and antenna calibration through analytical inversion of radio measurements performed using a system of two or three electric dipole antennas on a three‐axis stabilized spacecraft
Authors: Cecconi B. , Zarka P.
Published: May 2005

We present an analytical inversion method to achieve direction‐finding (DF) (i.e., retrieve the direction of arrival of an incoming electromagnetic wave, its flux, and its full polarization state) using radio measurements performed using a system of two or three electric dipole antennas on a three‐axis stabilized spacecraft. The Radio and Plasma Wave Science (RPWS) radio receiver on board Cassini includes such instantaneous DF capabilities, and so does the Solar Terrestrial Relations Observatory (STEREO) Waves radio receiver. We also present an analytical solution of the inverse problem which consists of calibrating the electric dipole orientations and effective lengths using a known radio source. Error sources (imperfect knowledge of antenna parameters, digitization errors, signal to noise ratio, etc.) and their propagation through the analytical inversion have been studied. The typical expected accuracy of our DF inversion is 1 dB [V2/Hz] for flux measurements, about 1–2° for source position and a few percent for degrees of polarization. For the antenna calibration procedure the expected accuracy is of the order of 2° on antenna direction and of 1% on antenna length. We define the data selection criteria to be used during both DF analysis and antenna calibration. We also discuss the limitations of the methods and the ways to improve their accuracy.
Average profiles of energetic and thermal electrons in the magnetotail reconnection regions
Authors: Imada S. , Hoshino M. , Mukai T.
Published: May 2005

We study plasma heating and acceleration around magnetic reconnection region by using GEOTAIL data. We carry out the superposed analysis of thermal temperature and energetic electrons flux as a function of distance from X‐type neutral line, for both the near‐Earth and the distant magnetotail. It is found that the enhanced energetic flux and high temperature regions are located around reconnection outflow region downstream away from the center of the X‐type neutral region. Those heated and accelerated regions are symmetric in both of the tail‐ and earth‐ward flow regions in the distant magnetotail, while in the near‐Earth magnetotail more energetic electrons are preferentially observed in the earthward flow region. In addition, we also study electron heating and acceleration during the passage of plasmoid, which may correspond to O‐type neutral line. We find the hot and energetic electrons behind the core of plasmoid but slightly away from the central plasma sheet.
Large negative lunar surface potentials in sunlight and shadow
Authors: Halekas J. S. , Lin R. P. , Mitchell D. L.
Published: May 2005

We survey Lunar Prospector Electron Reflectometer measurements from times when the Moon was located in the geomagnetic tail, in order to characterize the occurrence of large (>500 V) negative lunar surface potentials, as identified by upward‐going electron beams. We find that charging to these levels is rare, but that such charging events do occasionally occur in both sunlight and shadow. Large surface potentials are found primarily in the plasma sheet, and their occurrence depends mainly on the incident electron spectrum rather than surface properties. Most examples occur in shadow, where the current from energetic electrons dominates. However, some occur in sunlight, suggesting the occasional presence of either lower photoemission than expected or non‐monotonic potentials. Depending on the electric field scale height, significant electric fields of up to ∼100 V/m may sometimes exist at the lunar surface.
Tumour‐suppression activity of the proapoptotic regulator Par4
Authors: García‐Cao Isabel , Duran Angeles , Collado Manuel , Carrascosa Maria J , Martín‐Caballero Juan , Flores Juana M , Diaz‐Meco Maria T , Moscat Jorge , Serrano Manuel
Published: May 2005

The proapoptotic protein encoded by Par4 (prostate apoptosis response 4) has been implicated in tumour suppression, particularly in the prostate. We report here that Par4‐null mice are prone to develop tumours, both spontaneously and on carcinogenic treatment. The endometrium and prostate of Par4‐null mice were particularly sensitive to the development of proliferative lesions. Most (80%) Par4‐null females presented endometrial hyperplasia by 9 months of age, and a significant proportion (36%) developed endometrial adenocarcinomas after 1 year of age. Similarly, Par4‐null males showed a high incidence of prostate hyperplasia and prostatic intraepithelial neoplasias, and were extraordinarily sensitive to testosterone‐induced prostate hyperplasia. Finally, the uterus and prostate of young Par4‐null mice have increased levels of the apoptosis inhibitor XIAP (X‐chromosome‐linked inhibitor of apoptosis), supporting the previously proposed function of Par4 as an inhibitor of the ζPKC (atypical protein kinase)–NF‐κB (nuclear factor‐κB)–XIAP pathway. These data show that Par4 has an important role in tumour suppression, with a particular relevance in the endometrium and prostate.
Temperature hysteresis and thermal remagnetization in magnetic materials
Authors: Basso Vittorio , LoBue Martino , Bertotti Giorgio
Published: May 2005

A temperature-dependent Preisach model is introduced and discussed for the case where the Preisach distribution depends on temperature through scaling factors. By expressing the model in terms of temperature-independent variables, we derive expressions for the hysteretic magnetization response to cyclic temperature variations as a function of past field history. We apply these results to the interpretation of thermal remagnetization phenomena experimentally observed in hard magnetic materials.
Analysis of wasp-waist hysteresis loops
Authors: Bennett Lawrence H. , Della Torre Edward
Published: May 2005

Wasp-waist and pot-belly hysteresis loops have been observed in many materials. When only the major loop is reported, the results are insufficient to establish which processes are involved. We present two models for wasp-waist materials that produce virtually indistinguishable major loops, but show that first-order reversal curves can be used to separate the effects. In the simplest model, we take a soft magnetic material and a hard material and exchange couple them. When the exchange is positive, the loop is conventional. However, for negative (antiferromagnetic) exchange, the wasp-waist loop is obtained. Negative coupling of two materials with different switching field distributions leads to pot-bellied loops.
Mössbauer spectroscopy investigation of Mn-substituted Co-ferrite (CoMnxFe2−xO4)
Authors: Krieble K. , Schaeffer T. , Paulsen J. A. , Ring A. P. , Lo C. C. H. , Snyder J. E.
Published: May 2005

Understanding the effect of Mn substitution for Fe in Co ferrite presents a challenge because there are three different transition-metal ions distributed among two distinct crystallographic and magnetic sublattices with complicated superexchange and anisotropic interactions. In this study, a series of six powder samples with compositions Co1.0MnxFe2−xO4 were investigated using transmission Mössbauer spectroscopy. Mössbauer spectroscopy provides an excellent tool for probing the local environment of the Fe atoms present in such materials. Results show two sets of six-line hyperfine patterns for all samples, indicating the presence of Fe in both A and B sites. Identification of sites is accomplished by evidence from hyperfine distribution width, integrated intensity, and isomer-shift data. Increasing Mn concentration was found to decrease the hyperfine field strength at both sites, but at unequal rates, and to increase the distribution width. This effect is due to the relative strengths of Fe–O–X superexchange (X=Fe, Co, or Mn) and the different numbers of the next-nearest neighbors of A and B sites. Results are consistent with a model of Mn substituting into B sites and displacing Co ions onto A sites.
Effect of stress on the shape of ferromagnetic hysteresis loops
Authors: Schneider Carl S.
Published: May 2005

The shape of ferromagnetic hysteresis loops is described in terms of symmetric Brown and antisymmetric Bozorth stress fields. The magnetization and nonlinear stress dependence of stress fields are measured and plotted. The Brown field is found to exist in every magnetoelastic process and is manifested when hysteresis of 90° domain walls is asymmetric. Stress fields are derived from magnetoelastic energy density both within a ferromagnetic grain and throughout the sample and are a measure of domain structure. The common stress crossover of saturate curves is modeled in terms of fraction of 90° domain walls. The Brown stress field changes the coercive field and the Bozorth stress field changes remanence.
Structure and magnetic properties of chemically prepared mixtures of crystalline and amorphous Fe(B) nanoparticles
Authors: Gorea A. , Ekiert T. F. , Pearson E. A. , Unruh K. M.
Published: May 2005

A fine dispersion of crystalline and amorphous Fe(B) nanoparticles has been chemically prepared and its structural and magnetic properties compared to those of the corresponding single phase nanoparticles. The coercivity of the as-prepared dispersion was intermediate between that of the single phase crystalline and amorphous nanoparticles but less than expected from a simple rule of mixtures. Moreover, after annealing at temperatures below the crystallization temperature of the amorphous phase, the coercivity of the dispersion was reduced significantly below that of the single phase amorphous nanoparticles suggesting a modified interparticle interaction arising from the characteristic nanostructure of the dispersion.
Nanoparticles of Fe in SiO2: A superparamagnet with a collective state?
Authors: Roshko R. M. , Viddal C. A.
Published: May 2005

We present a detailed experimental characterization of the irreversible response of a thin film of nanodimensional Fe particles embedded in SiO2, which includes measurements of the field and temperature dependence of the field-cooled moment, the zero-field-cooled moment, the thermoremanent moment, and the isothermal remanent moment, as well as measurements of the relaxation of the moment with time following various field application and removal protocols. The data are analyzed within the framework of a Preisach ensemble of temperature-dependent, thermally activated, asymmetric double-well subsystems. The analysis allows us to estimate the thermal fluctuation field, and to reconstruct the Preisach spectrum of double-well dissipation fields and bias fields, and its evolution with temperature. Relaxation isotherms exhibit an age dependence which suggests that the free-energy landscape of the thermally blocked state may possess an organization similar to that which characterizes the collectively frozen state of spin glasses.
Remarks about a fuzzy approach to model scalar hysteresis
Authors: Finocchio G. , Carpentieri M. , Consolo G. , La Foresta F. , Azzerboni B.
Published: May 2005

This article presents a generalization of a fuzzy model (FM) of scalar hysteresis in order to describe the experimental behavior of magnetic materials when the uniform domains motion hypothesis is not satisfied. Furthermore, several remarks are made regarding the choice of the data needed for the identification problem solution. Advantages of the FM compared to the Preisach model are also presented.
Influence of ordering phenomena on the magnetostriction of high Si alloys for electrical applications
Authors: Ros-Yanez Tanya , Ruiz Daniel , Lopez Diego , Hilgert Tom , Dupré Luc , Vandenberghe Robert E. , Houbaert Yvan
Published: May 2005

The present work attempts to assess the influence of order phenomena on the magnetostriction of high Fe–Si alloys for electrical applications. The magnetostriction of high silicon electrical steels in the range of 4to6wt.% Si was studied regarding the effect of processing and thermal treatment. In addition, power losses and saturation magnetization measurements were performed and Fe57 Mössbauer spectroscopy was used to evaluate and quantify the degree of order.
Critical fields and pulse durations for precessional switching of perpendicular media
Authors: Mayergoyz I. , Dimian M. , Bertotti G. , Serpico C.
Published: May 2005

Precessional switching of magnetization in perpendicular media induced by short rectangular pulses applied at arbitrary angles with respect to anisotropy axis, are studied. The expressions for critical magnetic fields and pulse durations that guarantee precessional magnetization reversals are derived.
Subnanosecond vortex transformation in ferromagnetic film elements observed by stroboscopic wide-field Kerr microscopy
Authors: Neudert Andreas , McCord Jeffrey , Schäfer Rudolf , Schultz Ludwig
Published: May 2005

The magnetization dynamics of a Ni81Fe19 disk of 16μm diameter and 50nm thickness was measured by time-resolved stroboscopic wide-field Kerr microscopy with a temporal resolution of less than 25ps. Time resolution is obtained by illumination with a frequency-doubled high-power Nd:YVO4 solid-state laser. The ground state of the magnetization is excited with a 700-ps-wide pulse of about 1.2kA∕m amplitude. After a fast rotation of magnetization and vortex displacement due to the pulsed magnetic field the magnetization slowly relaxes back to the ground state. During relaxation of the vortex we observe in the center of the element a stretched vortex structure that could be a 180° wall or a superposition of two vortices with switched core magnetization.
Anisotropic ternary Pr13Fe80B7 powders prepared by hydrogenation disproportionation desorption recombination process
Authors: Han Jing-zhi , Liu Shun-quan , Du Hong-lin , Yang Jin-bo , Yang Ying-chang
Published: May 2005

High-purity ternary Pr13Fe80B7 magnetic powder with high anisotropy is obtained by a modified hydrogenation disproportionation desorption recombination (HDDR) process in this work. This powder exhibits a record-high Br of 1.05T, and has a good crystal texture along the c axis. It is found that the formation of HDDR Pr13Fe80B7 anisotropy is related to a rodlike disproportionation microstructure. We also show that by changing the HDDR conditions, an intrinsic coercivity of 800kA∕m and an energy product of 144kJ∕m3 are obtained on this powder. The details of the modified HDDR process are also presented in this paper.
Magnetic, dielectric, and microwave absorbing properties of iron particles dispersed in rubber matrix in gigahertz frequencies
Authors: Kim Sung-Soo , Kim Sun-Tae , Yoon Yeo-Choon , Lee Kyung-Sub
Published: May 2005

This study investigates high-frequency magnetic, dielectric, and microwave absorbing properties of iron particles dispersed in rubber matrix for the aim of thin microwave absorbers in gigahertz frequencies. High value of magnetic permeability and dielectric constant can be obtained in the composites containing thin flake iron particles which were prepared by mechanical forging of spherical iron powders using an attrition mill. The results are attributed to the reduction of eddy current loss (increase of permeability) and enhancement of space-charge polarization (increase of permittivity). However, if the initial particle size is too small (approaching to skin depth), milling effect for the increase of permeability is not observed and a low dielectric constant is predicted. If the particle size is too large, the permeability value is too small due to strong eddy current loss. With the iron particles controlled in size and shape (flakes) as the absorbent fillers, the thickness can be reduced as low as 1mm with respect to −5dB reflection loss in 1–2GHz.
Co Fe 2 O 4 nanostructures with high coercivity
Authors: Jung J.-S. , Lim J.-H. , Choi K.-H. , Oh S.-L. , Kim Y.-R. , Lee S.-H. , Smith D. A. , Stokes K. L. , Malkinski L. , O’Connor C. J.
Published: May 2005

Nanometer-sized ferrite magnetic materials are the subject of intense research interest due to their potential applications in high-density magnetic information storage. One of the most explored ferrite materials is the cobalt ferrite (CoFe2O4). We have synthesized cobalt ferrite nanowires using cobalt ferrite nanoparticles in a porous anodic alumina template (AAT). The process of embedding ferrimagnetic particles into the pores was assisted by the magnetic field of a permanent magnet placed in vacuum directly under the substrate. Particles synthesized in the template were subsequently annealed at 600°C for 2h in Ar gas forming arrays of cobalt ferrite nanowires inside the AAT. The morphology of the ferrite before and after annealing was observed using a field-emission scanning electron microscope. The crystallographic structure of the nanowires was analyzed using x-ray diffraction and transmission electron microscopy. The magnetization was measured by a superconducting quantum interference device. The coercivity of the annealed ferrite in the form of nanowires is significantly larger than that of the separate ferrite nanoparticles in the pores. This effect is due to the clustering of nanoparticles when the organic solvent is removed by high-temperature annealing as well as an improvement in the crystallininty of the ferrite by reduction of defects. The Faraday spectra of the nanowires were measured before and after annealing. A significant peak was observed at 725nm. The nanowire/AAT composite material had a Verdet constant of 0.1min∕(Oecm) at the peak. It is important to mention that not only the properties but also the form of the material—a regular array of pillars—may be important for microelectronic or information storage applications.
Dynamic and wide field domain observation of amorphous ribbons with longitudinal Kerr effect microscopy
Authors: Takezawa M. , Kitajima K. , Morimoto Y. , Yamasaki J.
Published: May 2005

Wide field and dynamic domain observation has been done to investigate re-entrant characteristics of amorphous ribbons by adjusting a light path of a Kerr microscope and by triggering a CCD camera. It has been shown that a wide field of 2.6mm×2.3mm with less image distortion was achieved by critical modulation of the light path between an objective lens and samples. The remagnetization process of amorphous ribbons with pinned walls starts with wall depinning and reverse domain nucleation.
Structural evolution of Fe80C20 alloy with alloying times
Authors: Yoo Yong-Goo , Paek Mun-Cheol , Greneche J. M. , Yang Dong-Seok , Yu Seong-Cho
Published: May 2005

The structural evolution of mechanically alloyed Fe-C alloys was studied as a function of alloying times. The effect of alloying time on local structural changes of Fe-C has been investigated by means of Fe57 Mössbauer spectrometry, extended x-ray-absorption fine structure (EXAFS), and x-ray diffraction (XRD). XRD pattern from 24h alloyed Fe-C powder indicates at least the mixture of bcc-Fe and Fe3C phases. Mössbauer spectra analysis reveals that bcc-Fe decreases to the detriment of Fe3C phase with increasing alloying time, while both carbon-containing bcc-Fe and amorphouslike phase assigned to Fe located in grain boundaries (estimated at two atomic layers) remain alloying time independent. The variation of Fe3C phase content is in a good agreement with that observed by EXAFS analysis.
Magnetic properties of Sc-substituted ytterbium iron garnet under high dc field (33 Tesla)
Authors: Guillot Maurice , Ostorero Jean , Armstrong Gordon , Zhang Fang , Xu You
Published: May 2005

Magnetic measurements were performed on Yb3Fe5−xScxFe5O12(YbIG:Sc), x=0.5, single crystal platelets oriented along and perpendicular to the [111] crystallographic direction, in the 1.5–20 K temperature range in a magnetic field up to 330 kOe. Along the [110] and [100] axis H was limited to 230 kOe in the 4.2–300 K range. When H is parallel to [111] and [110] a first-order field induced transition are observed below about 10 K; the temperature variations of the transition field are very different. When H is applied along [100] a monotonous behavior is simply found. A noticeable anisotropy between the magnetic properties of the three samples remains present up to about 100 kOe. For the [111] sample the saturation is attained under 250 kOe below 10 K; the magnetic moment per Yb3+ ion that is deduced to be 1.78±0.05Bohr magneton confirms the strong quenching of the orbital moment by the crystalline field. In the intermediary field range (≈100–220kOe), there exists no more magnetic anisotropy. The magnetization that is proportional to the applied H is characterized by the onset of a field-induced magnetic structure; the Yb–Fe exchange constant is then determined. When H lies in the (111) plane, a strong M reduction is noted in the whole H domain; however, the transition field, the linear H Yb–Fe variation domain and the saturation field are the same as along the [111] direction.
Reversal modes of simulated iron nanopillars in an obliquely oriented field
Authors: Thompson S. H. , Brown G. , Rikvold P. A.
Published: May 2005

Stochastic micromagnetic simulations are employed to study switching in three-dimensional magnetic nanopillars exposed to highly misaligned fields. The switching appears to proceed through two different decay modes, characterized by very different average lifetimes and different average values of the transverse magnetization components.
Micromagnetic simulations of hysteresis loops in ferromagnetic Reuleaux’s triangles
Authors: Muñoz-Sandoval E. , Torres-Heredia J. J. , López-Urías F.
Published: May 2005

We investigate the magnetic behavior of Fe, Co, Ni, and permalloy nanomagnets using micromagnetic simulations. We propose a Reuleaux’s triangle geometry shape for the individual nanomagnets. Reuleaux’s triangle combines the equilateral triangle and circular geometry. The effects of varying the thickness (10, 20, and 40nm) of these structures on the remanence magnetization and the coercive field are analyzed. Our results demonstrate that in most cases the hysteresis loops follow C, Ω, and vortex configurations in the magnetization reversal process. In addition, the magnetic properties of the small arrays of these nanomagnets are presented.
Numerical integration of Landau–Lifshitz–Gilbert equation based on the midpoint rule
Authors: d’Aquino M. , Serpico C. , Miano G. , Mayergoyz I. D. , Bertotti G.
Published: May 2005

The midpoint rule time discretization technique is applied to Landau–Lifshitz–Gilbert (LLG) equation. The technique is unconditionally stable and second-order accurate. It has the important property of preserving the conservation of magnetization amplitude of LLG dynamics. In addition, for typical forms of the micromagnetic free energy, the midpoint rule preserves the main energy balance properties of LLG dynamics. In fact, it preserves LLG Lyapunov structure and, in the case of zero damping, the system free energy. All the above preservation properties are fulfilled unconditionally, namely, regardless of the choice of the time step. The proposed technique is then tested on the standard micromagnetic problem No. 4. In the numerical computations, the magnetostatic field is computed by the fast Fourier transform method, and the nonlinear system of equations connected to the implicit time-stepping algorithm is solved by special and reasonably fast quasi-Newton technique.
Heating rate and anomalous final texture in 3% Si–Fe alloy strips
Authors: Kim S. B. , Heo N. H.
Published: May 2005

In inhibitor-free 100-μm-thick 3% Si–Fe alloy strips containing 70ppm of sulfur, a magnetic induction higher than 1.9T that resulted from {110}⟨001⟩ Goss grains was obtained at an extremely low or high heating rate. This is mainly due to the sluggish growth of {100} or {111} grains during the selective growth in the former and due to the active growth and the resultant enlargement of the {110}⟨001⟩ grains after nucleation in the latter. At a medium heating rate, the strips were finally composed of {100}⟨uvw⟩ grains due to the active selective growth of the {100} or the {111} grains, showing a poor magnetic induction of around 1.6T.