bluuebunny/crossref_metadata_2025_split huggingface dataset:
Der Bär ist los: Chemie mit Gummibärchen
Authors: Full Roland 
Published: January 2004

AbstractDas Gummibärchen birgt ein hohes Motivationspotenzial, das auch für im Chemieunterricht genutzt werden kann. Die beschriebenen Experimente wollen einen Beitrag dazu leisten, aus dem Objekt der Essbegierde ein Objekt der Wissbegierde zu machen. Die vorgestellte „Gummibärchen‐Chemie”︁ reicht von einfachen Untersuchungen zur Schwimmfähigkeit des Gummibärchens über Nachweisreaktionen seiner organischen Inhaltsstoffe bis hin zu Anwendungen aus der Bio‐ und Elektrochemie.
Kolloide: Die Welt der vernachlässigten Dimensionen
Authors: Hofmann Thilo 
Published: January 2004

AbstractAquatische Kolloide sind in allen natürlichen Gewässern vorhanden. Sie umfassen anorganische Kolloide wie Tonminerale, organische Kolloide wie Huminstoffe, Mikroorganismen und anthropogen eingetragene Kolloide wie Ruß oder Platin aus Katalysatoren. Kolloide können hydrophobe organische Schadstoffe sorbieren und transportieren oder nachteilig die Wasserqualität beeinflussen (z.B. pathogene Keime). Sie können die Leistung von Brunnen durch Verblockung der Porenräume im Grundwasser mindern. Kolloide können jedoch auch zur Sanierung von Grundwasserschadensfällen eingesetzt (Tenside) oder in der Wasseraufbereitung verwendet werden (Flockungsmittel, Katalysatoren). Kolloide entstehen oder werden mobilisiert durch Verwitterungsprozesse, Umsetzung organischer Substanzen, Auflösungs‐ und Fällungsprozesse sowie hydrochemische und hydraulische Veränderungen. Ihre Stabilität wird maßgeblich von den Oberflächeneigenschaften bestimmt. Viel versprechende neue analytische Techniken wie die Feld‐Fluss‐Fraktionierung, Laserinduzierte Breakdown‐Detektion oder Röntgenmikroskopie werden unser Verständnis von aquatischen Kolloiden in den kommenden Jahren erweitern.
Flüssigkristall‐Anzeigen
Authors: Borchard‐Tuch Claudia 
Published: January 2004

AbstractSichtbarer Ausdruck des elektronischen Zeitalters ist die fast überall anzutreffende digitale Anzeige von Daten und Bildern, und Displays sind die wichtigste und gleichzeitig auch teuerste Schnittstelle zwischen Mensch und Maschine. Allein im dritten Quartal 2003 wurden weltweit über 130 Millionen Handy‐Displays produziert.
Die Angst des Chemikers vor dem fugu
Authors: Roth Klaus 
Published: January 2004

AbstractDas hochwirksame Gift des fugus faszinierte die Menschen schon seit Urzeiten. Erst 1964 gelang die Strukturaufklärung des Tetrodotoxin, das sich als eine chemisch ungewöhnliche Verbindung entpuppte. Das Gift ist ein unersetzliches Handwerkszeug bei Untersuchungen von neuronalen Prozessen, da Na+‐Kanäle hochselektiv blockiert werden können. Dass der fugu, trotz seiner Giftigkeit, seit Jahrhunderten von japanischen Gourmets als unvergleichliche Delikatesse geschätzt wird, mag uns Europäern unverständlich sein, erinnert uns aber daran, dass kulturelle Unterschiede reizvoll sind und mit Toleranz und Neugier begegnet werden sollten. Jedes Jahr findet in Shimonoseki eine Trauerfeier unter großer Beteiligung der Bevölkerung statt. Nicht wegen der menschlichen Opfer, sondern wegen der verstorbenen Fische. Shinto‐Priester beten für sie und geben eine größere Zahl gefangener fugus symbolisch als Dank an das Meer zurück.
Chemische Kampfstoffe
Authors: Hildebrandt Henry 
Published: January 2004

AbstractVergangenheitsbewältigung und aktuelle Aufgabe. Teil 2Bis in die 1970er Jahre hinein war es weltweit üblich, ausrangierte Chemiewaffen im Meer zu versenken. Amerikaner und Russen kippten sie in der Ostsee oder im Atlantik über Bord, Briten entsorgten Nervengifte vor der irischen Küste. Italien wählte seine Adria, um die Reste seines chemischen Arsenals loszuwerden, das es im Äthiopienkrieg 1936 eingesetzt hatte.
Hsp90‐Blocker treffen Krebszellen zielsicher
Authors: Groß Michael 
Published: January 2004

AbstractHitzeschockproteine sind eine universell verbreitete Antwort der Zelle auf Hitzestress. Viele von ihnen dienen der Zelle als molekulare Chaperone, das heißt sie können andere Proteine vorübergehend an sich binden und vor der Entfaltung und Verklumpung zu unlöslichen Aggregaten schützen. Hsp90 ist ein Chaperon, dessen Funktion noch nicht vollständig aufgeklärt ist, das aber eine Schlüsselrolle im komplexen Netzwerk der zellulären Funktionen zu spielen scheint. Die von ihm behüteten Proteine sind oft wichtige Regulatoren, wie etwa Transkriptionsfaktoren oder Hormonrezeptoren.
Druck genügt
Authors: Groß Michael 
Published: January 2004

AbstractForscher am MIT haben eine neue Art von Zweikomponenten‐Kunststoff entwickelt, der sich schon bei Zimmertemperatur allein durch Druck in einen zähflüssigen Zustand versetzen und in neue Formen pressen lässt.http://www.michaelgross.co.uk
COMSPIRA: A common approach to spiral and radial MRI
Authors: Rodríguez Ignacio , Pérez De Alejo Rigoberto , Cortijo Manuel , Ruiz‐Cabello Jesús 
Published: January 2004

AbstractThe choice of what type of k‐space coverage should be used depends on a given application and hardware limitations. So far, radial‐ and spiral‐collected data have physical analogies in terms of sequence design, although they have not been presented, to our best knowledge, under the same pulse sequence. A mathematical formulation behind the combination of these non‐Cartesian sampling methods under the same pulse sequence [(COMSPIRA) combined spiral and radial] is presented in this study. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 20B: 40–44, 2004.
Target field design for MAMBA step fields
Authors: Lee K.J. , Paley M.N.J. , Barber D.C. , Wilkinson I.D. , Griffiths P.D. 
Published: January 2004

AbstractMultiple Acquisition with Micro‐B0 Array (MAMBA) is a class of parallel imaging techniques. Its distinguishing feature is the use of auxiliary coil arrays that introduce a stepped field within the B0 field. The steps form regions of uniform field, which then can be used to encode in one or more dimensions. The steps can also be used in conjunction with sensitivity encoding (SENSE) techniques to achieve higher acceleration factors. Step fields necessarily contain high‐order harmonics and require high currents to implement them. To reduce current demands, we have combined the pseudoinverse target field method with subset selection and Tikhonov regularization to derive coil array designs for some MAMBA configurations. We conclude that MAMBA will be most effective in long and narrow or thin and flat configurations. In these situations, our algorithm enables sparse designs with low current demands to be obtained. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 20B: 1–8, 2004.
Tissue‐equivalent phantoms for high frequencies
Authors: Beck B.L. , Jenkins K.A. , Rocca J.R. , Fitzsimmons J.R. 
Published: January 2004

AbstractSaline phantoms have been used traditionally as biological mimics to load radio frequency (RF) coils during development and testing. However, the relative permittivity of biological tissues diverges from that of water as frequencies increase, resulting in saline phantoms loading coils much differently than the real biological systems. We have developed tissue‐equivalent phantoms with compartments containing gels that approach the relative permittivities and conductivities of a rat at 470 MHz. The gel characteristics are measured with a coaxial probe and the coil‐loading characteristics of the assembled phantoms are compared with real animals. It is shown that the tissue‐equivalent phantoms load coils similarly to live rats, unlike the saline phantoms. Using these tissue‐equivalent phantoms, the coil designer can be confident that when the coil leaves the laboratory to be used in the magnet, it will be optimized for the biological system of interest. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 20B: 30–33, 2004.
Design and implementation of a uniplanar gradient field coil for magnetic resonance imaging
Authors: Lemdiasov Rostislav , Ludwig Reinhold , Brevard Mat , Ferris Craig 
Published: January 2004

AbstractA new approach to design uniplanar gradient coils for magnetic resonance imaging (MRI) is presented. The theoretical formulation involves a constraint cost function between the desired field in a particular region of interest in space and the current‐carrying coil plane based on Biot‐Savart's integral equation. An appropriate weight function in conjunction with linear approximation functions allows the transformation of the problem formulation into a linear matrix equation in which its iterative solution yields discrete current elements in terms of magnitude and direction within the prescribed coil plane. These current elements can be synthesized into an overall practical wire configuration by suitably adding individual wire loops. Numerical predictions and practical testing for aGygradient coil underscore the success of this approach in terms of achieving a highly linear field while maintaining low parasitic fields. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 20B: 17–29, 2004
Real‐time modulation of acoustic gradient noise in interventional MRI
Authors: Moelker Adriaan , Vogel Mika W. , Pattynama Peter M.T. 
Published: January 2004

AbstractAcoustic noise is inherent to magnet resonance imaging (MRI) and poses safety risks to patients and interventional radiologists. Although a spectrum of noise reduction techniques has been implemented, new developments further increase sound levels. Silent pulse sequences based on derating gradient currents have been proposed but are limited to slow pulse sequences not suitable for interventional MRI (iMRI). However, iMRI does not continuously require fast imaging with high image update rates. Therefore, the aim of this study was to develop a tool that could remotely derate the gradient currents in real time, operated by the interventionalist. The duration of the derated gradients is increased to retain image resolution [this extends imaging time and echo time (TE)]. The experiment setup consisted of a custom‐built remote controller located in the interventional MR room. A fast spoiled gradient recalled echo (FSPGR) sequence was tested and acoustic recordings were made with a microphone in the magnet bore. An optical link sent data from the remote controller to a computer that was connected to a 1.5‐T cardiovascular MR scanner over ethernet. A software server installed on the MR system received the requests and passed these on to the integrated pulse generator in order to control the real‐time imaging. Slew rate adjustments were accomplished by calculating instruction period changes and adjusted waveform amplitudes accordingly. The experimental setup reduced the slew rate up to 16‐fold, which resulted in a considerable acoustic noise reduction of 21.1 dBA. The remote controller performed well and image quality showed no substantial qualitative changes. We made use of the previously described idea of silent pulse sequence designing. Although derating is at the expense of the image refresh rate, our real‐time slew rate reduction is compatible with the fact that iMRI procedures do not continuously require fast image update rates. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 20B: 34–39, 2004.
Connexin35/36 gap junction proteins are expressed in photoreceptors of the tiger salamander retina
Authors: Zhang Jian , Wu Samuel M. 
Published: January 2004

AbstractPhotoreceptors in the vertebrate retina are electrically coupled with one another. Such coupling plays important roles in visual information processing. Physiological properties of rod‐rod and rod‐cone coupling have been best studied in the salamander retina, yet the cellular and molecular basis of these electrical synapses has not been established. Recently, connexin35/36 (Cx35/36) gap junction proteins were found to be highly expressed in brain and retina, suggesting that it may mediate photoreceptor coupling. To test this idea, we examined the cellular distribution of Cx35/36 in the salamander retina. Western blot analysis showed the expression of Cx35/36 proteins, and confocal microscopy revealed characteristic punctate Cx35/36 immunoreactivity in both synaptic layers. In addition, Cx35/36‐positive plaques were detected in the outer nuclear layer (ONL) between neighboring rods, and these plaques outlined the mosaic of the rod network at a level distal to the external limiting membrane. Moreover, although Cx35/36 plaques were detected between some cones and their adjacent rods, the number and size of these plaques was smaller, and their staining intensity was diminished compared with the plaques between adjacent rods. Furthermore, Lucifer yellow injection together with confocal microscopy revealed that Cx35/36‐puncta were colocalized with finlike structures of rod cell membrane, with the ultrastructure of gap junctions between paired rod fins having been found by electron microscopy. Therefore, our findings demonstrate that Cx35/36 expression in photoreceptors is primarily located between rods and to a lesser extent between rods and cones, suggesting that Cx35/36 may participate in electrical coupling between rods and between rods and cones in the salamander retina. J. Comp. Neurol. 470:1–12, 2004. © 2004 Wiley‐Liss, Inc.
Bromodeoxyuridine administered during neurogenesis of the projection neurons causes cerebellar defects in rat
Authors: Sekerková Gabriella , Ilijic Ema , Mugnaini Enrico 
Published: January 2004

AbstractBromodeoxyuridine (BrdU) is broadly used in neuroscience to study embryonic development and adult neurogenesis. The potential toxicity of this halogenated pyrimidine analogue is frequently neglected. In this study, we administered BrdU in small doses by the progressively delayed cumulative labeling method to immunocytochemically tag different cerebellar cell types with antibodies to specific markers and BrdU in the same section. The well‐known structure of the cerebellum made it possible to ascertain several toxic effects of the treatment. Time‐pregnant rats were given five or six injections of 5 or 6 mg of BrdU (∼12–20 mg/kg) at 8‐hour intervals over 2 successive days between day 11 and 21 of pregnancy (E11–E12 to E20–E21), and the adult progeny was processed by immunocytochemistry. We demonstrate that this treatment effectively labeled distinct cerebellar cell populations but produced striking defects in the proliferation, migration, and settling of the Purkinje cells; reduced the size of the cerebellar cortex and nuclei; produced defects in the patterning of foliation; and also affected litter size, body weight, and mortality of the offspring. The observed toxic effects were consistent within individual treatment groups but varied between different treatment groups. Treatment with BrdU at the peak of neurogenesis of cerebellar projection neurons (E14) produced the most severe malformations. We observed no overt effects on the timing of neurogenesis for cerebellar neurons and glia across experimental groups. In conclusion, BrdU is a useful tool to study neural development, but its cytotoxicity represents a serious pitfall particularly when multiple doses are used to label cells. J. Comp. Neurol. 470:221–239, 2004. © 2004 Wiley‐Liss, Inc.
Altered epithelial density and expansion of bulbar projections of a discrete HSP70 immunoreactive subpopulation of rat olfactory receptor neurons in reconstituting olfactory epithelium following exposure to methyl bromide
Authors: McMillan Carr Virginia , Ring George , Youngentob Steven L. , Schwob James E. , Farbman Albert I. 
Published: January 2004

AbstractA previously described subpopulation of rat olfactory receptor neurons, the 2A4(+)ORNs, is 1) distinguished by intense constitutive cytoplasmic immunoreactivity to antibodies to the 70‐kD heat shock protein (HSP70); 2) occurs sparsely but consistently through ventral and lateral olfactory epithelium (OE); and 3) projects to just two to three consistently located glomeruli in each olfactory bulb (OB) (Carr et al. [1994] J Comp Neurol 348:150–160). Immunoreactivity appears not to be stress‐related. To examine the persistence of these features following destruction and reconstitution of the OE, rats were subjected to methyl bromide‐induced OE lesion (Schwob et al. [1995] J Comp Neurol 59:15–37; Schwob et al. [1999] J Comp Neurol 412:439–457] and their OE and OBs examined with antibodies to HSP70 6–10.5 weeks postlesion. Lesioned OE showed significantly increased 2A4(+)ORN densities but no alteration of 2A4(+)ORN zonal distribution. The OBs of lesioned animals showed marked expansions of 2A4(+)ORN bulbar projections, with 2–15‐fold increases in numbers of glomeruli showing 2A4(+)axons, and projection expansions were greater in animals maintained on chronic food restriction prior to lesioning. Examination of archival 5‐month post‐MeBr lesion material indicates that altered projection patterns are maintained. J. Comp. Neurol. 469:475–493, 2004. © 2004 Wiley‐Liss, Inc.
Distribution of corticotropin‐releasing factor‐immunoreactive neurons in the central nervous system of the domestic chicken and Japanese quail
Authors: Richard Sabine , Martínez‐García Fernando , Lanuza Enrique , Davies D. Ceri 
Published: January 2004

AbstractIn birds, as in mammals, corticotropin‐releasing factor (CRF) is present in a number of extrahypothalamic brain regions, indicating that CRF may play a role in physiological and behavioral responses other than the control of adrenocorticotropin hormone release by the pituitary. To provide a foundation for investigation of the roles of CRF in the control of avian behavior, the distribution of CRF immunoreactivity was determined throughout the central nervous system of the domestic chicken (Gallus domesticus) and Japanese quail (Coturnix japonica). The distribution of CRF‐immunoreactive (‐ir) perikarya and fibers in the chicken and quail brain was found to be more extensive than previously reported, notably in the telencephalon. Numerous CRF‐ir perikarya and fibers were present in the hyperstriatum, hippocampus, neostriatum, lobus parolfactorius, and archistriatum, as well as in the nucleus taeniae, nucleus accumbens, and bed nucleus of the stria terminalis, which exhibited the strongest immunolabeling in the telencephalon. The presence of dense populations of CRF‐ir perikarya in the medial lobus parolfactorius, nucleus of the stria terminalis, and paleostriatum ventrale, apparently giving rise to CRF‐ir projections to the mesencephalic reticular formation, the parabrachial/pericerulear region, and the dorsal vagal complex, suggests that these telencephalic areas may constitute part of the avian “central extended amygdala.” These results have important implications for understanding the role of extrahypothalamic CRF systems in emotional responses in birds. J. Comp. Neurol. 469:559–580, 2004. © 2004 Wiley‐Liss, Inc.
Synaptic connectivity of the diffuse bipolar cell type DB6 in the inner plexiform layer of primate retina
Authors: Jusuf Patricia R. , Lee Sammy C.S. , Grünert Ulrike 
Published: January 2004

AbstractDiffuse bipolar cells in primate retina receive synaptic input from multiple cones and provide output to ganglion cells. Diffuse bipolar cells can be subdivided into six types (DB1–DB6) according to the stratification of their axon terminals in the inner plexiform layer, but their synaptic connectivity in the inner plexiform layer is not well understood. Here the stratification and synaptic connectivity of DB6 axon terminals were studied in the retinae of New World (marmoset) and Old World (macaque) monkeys. Immunohistochemical markers were applied to retinal sections. The sections were analyzed by confocal and deconvolution light microscopy as well as electron microscopy. The DB6 cells were identified with antibodies against CD15; rod bipolar cells were identified with antibodies against protein kinase Cα (PKCα); and AII amacrine cells were identified with antibodies against calretinin. The axons of DB6 and rod bipolar cells occupy distinct regions in stratum 5 of the inner plexiform layer. The distal processes of calretinin‐labeled AII cells are usually closely associated with rod bipolar axons but sometimes also with DB6 axons. Pre‐embedding immunoelectron microscopy showed that the vast majority (over 86%) of the synaptic output of DB6 cells is onto amacrine cell processes, whereas less than 14% goes to ganglion cell processes. In double‐labeled preparations DB6 axons occasionally made output onto calretinin‐labeled amacrine processes. Thus it is possible that AII cells receive some input from DB6 cells. J. Comp. Neurol. 469:494–506, 2004. © 2004 Wiley‐Liss, Inc.
Effects of two years of estrogen loss or replacement on nucleus basalis cholinergic neurons and cholinergic fibers to the dorsolateral prefrontal and inferior parietal cortex of monkeys
Authors: Tinkler Gregory Paul , Tobin Joseph Raphael , Voytko Mary Lou 
Published: January 2004

AbstractThe present study examined the long‐term (2 years) effects of estrogen loss or estrogen replacement therapy (ERT) on cholinergic neurons in the nucleus basalis of Meynert and on cholinergic fibers in the prefrontal and parietal cortex of adult female cynomolgus monkeys. Cholinergic fiber density in layer II of the prefrontal cortex was decreased in monkeys who were ovariectomized and treated with placebo for 2 years. In contrast, ovariectomized monkeys receiving ERT for 2 years had fiber densities that were comparable to those of intact controls. No differences in parietal cholinergic fiber density or nucleus basalis cholinergic neuron number or volume were found among intact, ovariectomized, or ERT monkeys. Our results suggest that ERT is effective in preventing region‐specific changes in cortical cholinergic fibers that result from the loss of circulating ovarian hormones. These modest but appreciable effects on cholinergic neurobiology following long‐term estrogen loss and ERT may contribute to changes in visuospatial attention function that is mediated by the prefrontal cortex. J. Comp. Neurol. 469:507–521, 2004. © 2004 Wiley‐Liss, Inc.
Expression of androgen receptor mRNA in zebra finch song system: Developmental regulation by estrogen
Authors: Kim Yong‐Hwan , Perlman William R. , Arnold Arthur P. 
Published: January 2004

AbstractBy using improved methods for in situ hybridization to detect expression of androgen receptor (AR) mRNA, the distribution of expression was mapped in the adult male zebra finch brain. In the neural song circuit, robust expression was found in area X of the lobus parolfactorius (LPO) as well as in other song regions previously reported. Expression was also found in many areas of the hypothalamus and dorsal thalamic nuclei, nucleus intercollicularis and ventricular areas of the midbrain, cerebellar Purkinje and granule cells, the hyperstriatum, medial neostriatum, medial LPO, and archistriatum. In juvenile males, AR mRNA expression was first detected in nucleus high vocal center (HVC) at posthatch day 9 (P9), in area X at P9–P11, and in the region of the robust nucleus (RA) in the medial archistriatum by P7. Estrogen treatment of hatchling females caused an increase in the expression of AR mRNA in HVC and area X by P11, whereas treatment of hatchling males with the aromatase inhibitor fadrozole decreased the expression of AR mRNA at P11. The present results indicate that masculine development of AR expression begins in area X and HVC before they are thought to be synaptically connected, suggesting that different song nuclei initiate sexual differentiation independently of transsynaptic masculinizing influences. The present results suggest that estrogen is necessary for full masculine AR expression in the song system and that the estrogenic regulation of AR contributes to subsequent differential actions of androgen in male and female song nuclei. J. Comp. Neurol. 469:535–547, 2004. © 2004 Wiley‐Liss, Inc.