bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exposure to ultraviolet radiation causes apoptosis in developing sea urchin embryos
Authors: Lesser Michael P. , Kruse Valerie A. , Barry Thomas M. 
Published: October 2003

SUMMARYLaboratory exposures of embryos from the sea urchin Strongylocentrotus droebachiensis to ultraviolet B radiation (UV-B, 290-320 nm), equivalent to a depth of 1-3 m in the Gulf of Maine, resulted in significant damage to DNA measured as cyclobutane pyrimidine dimer formation. Cells with DNA damage caused by ultraviolet radiation (UVR, 290-400 nm) and oxidative stress can survive, but are often retained in the G1/S phase of the cell cycle to repair DNA as a result of the expression of cell cycle genes such as p53 and p21, and the subsequent inhibition of the activity of cyclin-dependent kinases such as cdc2; if DNA cannot be repaired it can lead to programmed cell death or apoptosis. Sea urchin embryos exposed to UV-B radiation exhibit significantly higher protein concentrations of the antioxidant enzyme superoxide dismutase, and the transcriptional activators p53 and p21. The downstream activator of the cell cycle,cdc2, showed significantly lower protein concentrations with exposure to increasingly shorter wavelengths of UVR. Decreases in cdc2 could have been caused directly by exposure to UV-B or as a result of downregulation via the p53, p21 cascade, or both. These cellular events lead to apoptosis, as shown by the significant increase in DNA strand breaks observed in the nuclei of developing embryos exposed to UVR using the TUNEL assay. Cellular death, and a decrease in sea urchin embryo survivorship,are caused by the indirect and direct effects of exposure to UVR that leads to apoptosis in these laboratory experiments.
Short-term transformation and long-term replacement of branchial chloride cells in killifish transferred from seawater to freshwater, revealed by morphofunctional observations and a newly established `time-differential double fluorescent staining' technique
Authors: Katoh Fumi , Kaneko Toyoji 
Published: October 2003

SUMMARY
Short- and long-term responses to direct transfer from seawater to freshwater were examined in gill chloride cells of killifish, which developed distinct freshwater- and seawater-type chloride cells in the respective environments. In a short-term response within 24 h after transfer,seawater-type chloride cells forming a pit structure on the apical surface were transformed into freshwater-type cells equipped with developed microvilli on the flat or projecting apical membrane, via the intermediate type. The transformation process was accompanied by the disappearance of apically located Cl- channel (cystic fibrosis transmembrane conductance regulator) and neighboring accessory cells. Chloride cell replacement was also examined as a long-term adaptation to freshwater transfer, using a newly established `time-differential double fluorescent staining (TDS)' technique. In the TDS technique, in vivo labeling of chloride cells was performed on two separate days, using two distinguishable mitochondria-specific fluorescent probes. For 3 days after freshwater transfer, 14.7% of seawater-type cells were replaced with newly differentiated freshwater-type cells, whereas these ratios of chloride cell replacement were much lower (1.2% and 1.8%) in seawater- and freshwater-maintained groups,respectively. In consequence, following direct transfer of killifish from seawater to freshwater, seawater-type chloride cells were transformed morphologically and functionally into freshwater-type cells as a short-term response, followed by the promotion of chloride cell replacement as a long-term response.
Efficient Transport of Saccharides through a Liquid Membrane Mediated by a Cyclodextrin Dimer
Authors: Ikeda Hiroshi , Matsuhisa Akiyuki , Ueno Akihiko 
Published: October 2003

AbstractA new efficient system for transporting saccharides through a liquid membrane has been constructed. The transport rates of saccharides were accelerated greatly by the cyclodextrin dimer 2; by contrast, the corresponding cyclodextrin monomer 1 was not effective at mediating saccharide transport. The transport rate of D‐ribose through a chloroform liquid membrane was 17 times faster when the cyclodextrin dimer 2 was used as the transporter than when the cyclodextrin monomer 1 was used. Similarly the transport rate of methyl D‐galactopyranoside was 16 times faster by 2 than by 1.
Bisporphyrins with Bischlorin Features Obtained by Direct Anodic Coupling of Porphyrins
Authors: Ruhlmann Laurent , Gross Maurice , Giraudeau Alain 
Published: October 2003

AbstractThe proximity of two or more porphyrin or chlorin‐like structures has been shown to be crucial in numerous biological processes, such as electron transfers. The one‐pot electrochemical synthesis of a dimeric tetraphenylporphyrin with one 1,2‐(diphenylphosphonium)benzene as a spacer and of its porphyrin‐monomer precursor are reported. These new compounds have been characterized by 1H and 31P NMR, ESR, and UV‐visible spectroscopy and microanalysis. Electrochemical data are reported, and the redox behavior is analyzed for the monomers and the dimers. Important interactions between the two chromophores and a phosphonium–phosphonium interaction have been observed. UV‐visible and 1H NMR data along with electrochemical behavior suggest that the positive charge carried by the two phosphonium units is in part delocalized onto the π system of the porphyrins, this gives an unexpected bis‐porphyrin with bischlorin spectroscopic features.
Formation of Quaternary Stereocenters by Copper‐Catalyzed Michael Reactions with L‐Valine Amides as Auxiliaries
Authors: Christoffers Jens 
Published: October 2003

AbstractExtensive investigations of chiral auxiliaries and active metals for Michael addition of 1,3‐dicarbonyl compounds with vinyl ketones are summarized. Our efforts result in a widely applicable auxiliary‐mediated, copper(II) acetate‐catalyzed procedure. For these purposes, L‐valine diethylamide is an optimal chiral auxiliary giving quaternary stereocenters with up to 99 % ee at ambient temperature. No inert or anhydrous conditions are required, the solvent is simply acetone, and the auxiliary can be recovered almost quantitatively after workup.
The Evolution of [{Ph2P(CH2)nPPh2}Pt(μ‐S)2Pt{Ph2P(CH2)nPPh2}] (n=2, 3) Metalloligands in Protic Acids: A Cascade of Sequential Reactions
Authors: Mas‐Ballesté Rubén , Aullón Gabriel , Champkin Paul A. , Clegg William , Mégret Claire , González‐Duarte Pilar , Lledós Agustí 
Published: October 2003

AbstractGiven the nucleophilicity of the {Pt2S2} ring, the evolution of [Pt2(μ‐S)2(P∩P)2] (P∩P=1,2‐bis(diphenylphosphino)ethane (dppe), 1,3‐bis(diphenylphosphino)propane (dppp)) metalloligands in the presence of the simplest electrophilic species, the proton, has been studied. Combined use of experimental and theoretical data has allowed the whole set of reactions ensuing the protonation of the {Pt2S2} core to be established. The titration of [Pt2(μ‐S)2(P∩P)2] with HCl or HClO4 was monitored mainly by 31P{1H} NMR and mass techniques. Characterization of all the species involved was completed with the determination of the crystal structure of [Pt(SH)2(P∩P)], for dppe and dppp, and [Pt3(μ3‐S)2(dppp)3](PF6)2. The first protonation step of the {Pt2S2} core leads to the stable [Pt2(μ‐S)(μ‐SH)(P∩P)2]+ complex, but the second step implies disintegration of the ring, thus giving rise to various mononuclear species. The subsequent evolution of some of these species allows regeneration of [Pt2(μ‐S)(μ‐SH)(P∩P)2]+, evidencing the cyclic nature of this process. Whereas the reaction pathway is essentially common for both phosphine ligands, dppe and dppp, the different coordinating ability of Cl− or ClO4− determines the nature of the final products, [PtCl2(P∩P)], [Pt3(μ3‐S)2(P∩P)3]Cl2 or [Pt3(μ3‐S)2(P∩P)3](ClO4)2. DFT calculations have corroborated the thermodynamic feasibility of the reactions proposed on the basis of experimental data.
Correlation effects in low dimensional electron systems: the electron‐hole bilayer
Authors: Senatore G. , De Palo S. 
Published: October 2003

AbstractWe review recent progress in the area of low‐dimensional electrons, which has been made possible mainly by the use of quantum simulations. We focus on DMC results for a symmetric electron‐hole bilayer, which we analyze in some detail. We also contrast the results of simulations with (i) the predictions of a mean field treatments and (ii) the results of approaches based on the dielectric formalism, such as the STLS and qSTLS schemes. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of inverse solution in two‐dimensional heat conduction problem using Laplace transformation
Authors: Monde Masanori , Hammad J. A. , Arima Hirofumi , Mitsutake Yuhichi 
Published: October 2003

AbstractAn inverse solution has been explicitly derived for two‐dimensional heat conduction in cylindrical coordinates using the Laplace transformation. The applicability of the inverse solution is checked using the numerical temperatures with a normal random error calculated from the corresponding direct solution. For a gradual temperature change in a solid, the surface heat flux and temperature can be satisfactorily predicted, while for a rapid change in the temperature this method needs the help of a time partition method, in which the entire measurement time is split into several partitions. The solution with the time partitions is found to make an improvement in the prediction of the surface heat flux and temperature. It is found that the solution can be applied to experimental data, leading to good prediction. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(7): 602–617, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10115
Improvement of inverse heat conduction solution using Laplace transformation: Method of partial division of time
Authors: Monde Masanori , Liu Wei , Arima Hirofumi , Mitsutake Yuhichi , Hammad J.A. 
Published: October 2003

AbstractAny solution for an inverse heat conduction problem makes the estimation of surface temperature and surface heat flux worsen in the case where these values behave like a triangular shape change with time. In order to compensate for this defect, Monde and colleagues, who succeeded in obtaining analytical inverse solutions using the Laplace transform technique, introduce a new idea where these changes over the entire measurement time can be split into several parts depending on the behavior. Therefore, an approximate equation to trace the measured temperature change can be derived, resulting in good estimation of surface temperature and surface heat flux even in the case of the triangular shape change and sharp change. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(7): 630–638, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10117
Hohe Lebensdauer, niedriger Verschleiß
Authors: Dobler K. , Schöfer J. , Meyer K. , Dornhöfer G. 
Published: October 2003

AbstractAufgrund steigender Anforderungen an Qualität und Lebensdauer moderner mechanischer Systeme ist die tribologische Forschung ein wichtiger Bestandteil des industriellen Entwicklungsprozesses. Neben Schadensanalysen gewinnt hier die Erarbeitung von produktbezogenem Wissen zunehmend an Bedeutung. Die Robert Bosch GmbH setzt daher seit Jahren modernste Analysetools wie das Focused Ion Beam System ein, mit dem sich kleinste Gefügeveränderungen nachweisen und so Verschleißentwicklungen dokumentieren lassen. Im Bereich der Kraftstoffeinspritzung erfordern neue Umweltgesetze die Entwicklung direkteinspritzender Systeme, die in der Lage sind, immer höhere Einspritzdrücke zu realisieren. Da die meisten dieser Systeme auf einer Kraftstoffschmierung basieren, ist die Gewährleistung der Systemfunktion über die gesamte Lebensdauer abhängig von einer ausreichenden Schmierfähigkeit der Otto‐ und Dieselkraftstoffe. Um diese sicherzustellen, ist eine permanente Erweiterung der bestehenden Wissensbasis und der tribologischen Prüfmethodik notwendig. Bei Produkten ohne funktionsbedingte Anwesenheit von Schmiermedien ist das zusätzliche Einbringen eines flüssigen oder konsistenten Schmierstoffes oft unverzichtbar. Bei der Robert Bosch GmbH wird daher die Entwicklung spezieller Hochleistungsschmierstoffe intensiv vorangetrieben.
Microstructural changes in the wear surface of high strength stainless austenitic steels
Authors: Berns H. , Gavriljuk V. G. , Petrov Y. N. , Schmalt F. , Tyshchenko A. 
Published: October 2003

AbstractHigh strength CrMn steels alloyed with C or N or C+N were subjected to grooving or impact wear. The interstitial content ranged from 0.44 to 0.87 mass%. The bulk structure was characterized by internal friction and TEM, while the wear surface was inspected by TEM, XRD and magnetic response. The bulk is fully austenitic and the Snoek‐like relaxation reveals a “frozen splitting” caused by interstitial / substitutional complexes. Deformation induced ε‐martensite is found in the grooving wear surface, but traces of α‐martensite are present only in the specimen of lowest interstial content corresponding to the lowest stability of austenite. Neither XRD nor the magnetic response give evidence of α‐martensite in the impact wear surface.
Multiorgan transplantation with a new organ‐chip technique in mice: Preliminary histological data
Authors: Brath Endre , Miko Iren , Kovacs Judit , Toth Ferenc F. , Fachet Jozsef , Furka Istvan 
Published: October 2003

AbstractA simple model was developed for multiorgan liver‐kidney‐spleen‐intestine transplantation on 108 inbred mice. Donor operations included hepatectomy, nephrectomy, splenectomy, and jejunum segment resection. Following removal of the organ, small slices or abdominal organ “chips” were prepared. During multiorgan recipient operations, chips from each of these organs were transplanted into the omentum; in the control single‐organ groups, only 1 organ was transplanted. All animals survived. Biopsies were taken for histology after 6 weeks. All organs were found to have developed a blood supply. In the liver chips, hypertrophied cells could be detected. In the margin of the kidney tissue, both the glomeruli and tubules were preserved. Lymphoid zone and red pulp were intact in spleen chips. All layers of the intestinal chips were identifiable and contained intraluminal mucinous substances. This model is a simple surgical intervention with the possibility of the investigation of 4 organs.Kísérletünk célja új, multiorgan máj‐vese‐lép‐vékonybél chip‐transzplantációs modell kidolgozása volt egerekben. Kísérletünkhöz 108 beltenyésztett egeret használtunk. Donor műtétek: hepatectomia, nephrectomia, splenectomia, és jejunum segment resectio. Az eltávolított szervekből kis szeleteket, “chip”‐eket alakítottunk ki. A multiorgan recipiens műtétek: minden szervből darabokat transzplantáltunk a csepleszbe, míg kontrollba csak egy szerv került. Minden állat túlélt: 6 hét múlva szövettani mintavétel történt. A chip‐vérellátás jól követhető volt. A máj “chip”‐ekben hipertrophiás sejteket találtunk. A vese darabok széli részén a glomerolusok és tubulusok megőrízték szerkezetüket. Jól körülírt lép fészkeket detektáltunk lympoid zónával és vörös pulpával. A bél falának minden rétegét, és mucin termelést sikerült azonosítani. A modell technikailag egyszerűen kivitelezhetü, előnye, hogy egyszerre 4 szerv vizsgálatára van lehetőség. © 2003 Wiley‐Liss, Inc. MICROSURGERY 23:466–469 2003
High‐efficiency doped polymeric organic light‐emitting diodes
Authors: Vaeth Kathleen M. , DiCillo John 
Published: October 2003

AbstractFabrication of polymer light‐emitting diodes based on emission from the phosphorescent molecule fac‐tris(2‐phenylpyridine) iridium doped into a poly(N‐vinyl carbazole) host are reported. For single‐layered devices with magnesium‐silver cathodes, the luminance efficiency at 20 mA/cm2 was measured as 8.7 cd/A. This efficiency could be increased by over a factor of two by incorporation of evaporated small‐molecule layers into the device structure. Significant increases in device efficiency were also obtained without these evaporated layers by modification of the electrodes. Incorporation of 3,4‐poly(ethylene dioxythiophene):poly(styrene sulfonate) at the anode improved the device efficiency but had little impact on drive voltage. Insertion of lithium fluoride at the cathode resulted in no improvement in performance for magnesium‐silver and aluminum cathodes, but a significant improvement was realized in efficiency and drive voltage for calcium‐aluminum cathodes. Excellent device performance was observed for all three cathode metals used in conjunction with cesium fluoride. Through optimization of the electrodes and emitter‐layer thickness, devices exhibiting efficiencies as high as 37.3 cd/A are realized. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2715–2725, 2003
Peeling the onion: NMDA dysfunction as a unifying model in schizophrenia
Authors: Javitt Daniel C. 
Published: October 2003

AbstractN-methyl-d-aspartate receptor (NMDAR) dysfunction plays a crucial role in schizophrenia, leading to impairments in cognitive coordination. NMDAR agonists (e.g., glycine) ameliorate negative and cognitive symptoms, consistent with NMDAR models. However, not all types of cognitive coordination use NMDAR. Further, not all aspects of cognitive coordination are impaired in schizophrenia, suggesting the need for specificity in applying the cognitive coordination construct.
Why do schizophrenic patients hallucinate?
Authors: Roelfsema Pieter R. , Supèr Hans 
Published: October 2003

AbstractPhillips & Silverstein argue that schizophrenia is a result of a deficit of the contextual coordination of neuronal responses. The authors propose that NMDA-receptors control these modulatory effects. However, hallucinations, which are among the principle symptoms of schizophrenia, imply a flaw in the interactions between neurons that is more fundamental than just a general weakness of contextual modulation.
Nutrient Budgets, Dynamics and Storm Effects in a Eutrophic, Stratified Baltic Lake
Authors: Schernewski Gerald 
Published: October 2003

AbstractBetween 1989 and 1998 the small eutrophic stratified Lake Belau was investigated intensively and multidisciplinarily. This article is a short, comprehensive summary and re‐evaluation of the hydrochemistry of the lake, with focus on nitrogen and phosphorus. In several aspects the lake can be regarded as a typical example of the glacial north German lakes. The 1960's and 1970's are characterised by heavy nutrient inputs and fast eutrophication. During the last two decades the external nutrient load, especially the phosphorus load into Lake Belau was significantly reduced. But phosphorus‐rich sediments and large areas with summerly anoxic sediment surface conditions cause intensive release of phosphorus from older deeper sediment layers. Annual budgets reveal that despite an average sediment accumulation of 3 mm a−1 the lake has lost its function as net phosphorus sink and it is very likely that internal eutrophication by the sediments will keep the lake in its eutrophic state during the next decades. Despite that, monthly budgets of five vertical layers show that the main phosphorus supplier for the phosphorus depleted epilimnion during summer is the creek Alte Schwentine.The annual nitrogen budget indicates groundwater and interflow water as well as atmospheric input as additional important nitrogen sources. 36% (98 μmol m −2 h−1 N) of all nitrogen input is lost to atmosphere mainly due to denitrification. The example of a heavy storm shows that about 10% of the annual nitrogen loss to the atmosphere can take place during a single day and in form of ammonia. The storm further made obvious that these unpredictable events can have strong impact on nutrient cycling and ecology in Lake Belau and the lake can become an unexpected nutrient source for downstream systems.
Aromaticity and Electron Affinity of Carbok‐[3]radialenes, k=0, 1, 2
Authors: Lepetit Christine , Brøndsted Nielsen Mogens , Diederich François , Chauvin Remi 
Published: October 2003

AbstractAromaticity enhancement is a possible driving force for the low reduction potentials of buta‐1,3‐diynediyl‐expanded [N]radialenes: this hypothesis is theoretically analyzed for the expanded [3]radialene prototype. This study is undertaken within a more general prospect, namely the evaluation of the variation of aromaticity with endocyclic and peripheral carbomeric expansion of [3]radialene and its mono‐ and dianions. The structures, denoted as [CH]6h[CC]3kcarbo‐[3]radialene(q) (h=0, 1; k=0, 1, 2; q=0, −1, −2), were optimized in relevant singlet, doublet, or triplet spin states at the B3PW91/6‐31G** level. They were found to be all planar. The structural aromaticity was measured through the average bond length dav over the [CC]3kcarbo‐[3]radialene core, and by the corresponding bond‐length equalization parameter σ(d), related to Krygowski's GEO. The magnetic aromaticity was measured by Schleyer's NICS values at the center of the rings. Regarding the relative variation of NICS and σ(d), two classes of species can be distinguished according to their endocyclic expansion level. The species with a nonexpanded (k=0) or doubly expanded (k=2) ring constitute the first class: they exhibit D3h symmetry and a strong correlation of NICS with σ(d). The species with a singly expanded ring (k=1) fall far from the correlation line, and constitute the second class. This class distinction is related to the degeneracy scheme of the frontier orbitals of the neutral representative. A finer appraisal of the electron (de)localization is brought by the ELF (Electron Localization Function) analysis of the electron density. It allows for a weighting of relevant resonance forms. Unsubstituted species are well described by the superimposition of two or three resonance forms. For (doublet spin state) monoanionic species, their respective weights are validated by comparison with AIM spin density. The weighted mean, n, of the formal numbers of paired πz electrons in the resonance forms was calculated and compared with the closest even integer of either forms 4m+2 or 4m. A density‐based continuous generalization of the orbital‐based discrete Hückel rule is then heuristically proposed through an analytical correlation of NICS versus σ(d), n, and S, the spin of the species. The frontier‐orbital‐degeneracy pattern of neutral species is discussed with respect to structural and magnetic aromaticity criteria. A decreasing HOMO–LUMO gap versus endocyclic expansion is obtained, but [CC]31carbo‐[3]radialene possesses the highest HOMO and LUMO energies. Vertical and adiabatic electron affinities of neutral and monoanionic species were also computed and compared with related experimental data.
Fluid flow and mass transfer in a sinusoidal wavy‐walled tube at moderate Reynolds numbers
Authors: Nishimura Tatsuo , Bian Yongning , Kunitsugu Koji , Morega Alexandru M. 
Published: October 2003

AbstractFluid flow and mass transfer characteristics in an axisymmetric sinusoidal wavy‐walled tube are experimentally investigated in the Reynolds number range of 50 to 1000. Attention is paid to the transitional flow, which is observed in the Reynolds number range of 160 to 200. In the laminar flow regime, wall shear stress and mass transfer rate increase with the slopes of 1 and 1/3, respectively, whereas in the turbulent flow regime they increase with the slopes of 3/2 and 3/5, respectively. In the transitional flow regime they increase dramatically, with a sharp slope. It is found that in this flow regime, laminar‐like motion and turbulent‐like motion alternatively take place at different time intervals. This is quite different from the flow instability for the wavy‐walled channel, where Tollmien‐Schlichting waves are observed. The flow instability in the wavy‐walled tube in the transitional flow regime is considered to be responsible for a significant increase in the wall shear stress and mass transfer rate. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(7): 650–661, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10121