bluuebunny/crossref_metadata_2025 huggingface dataset:
Infinite order sudden approximation for rotational energy transfer in gaseous mixtures
Authors: Goldflam R. , Green S. , Kouri D. J.
Published: February 2003

Rotational energy transfer in gaseous mixtures has been considered within the framework of the infinite order sudden (IOS) approximation. A new derivation of the IOS from the coupled states Lippmann–Schwinger equation is given. This approach shows the relation between the IOS and CS T matrices and also shows in a rather transparent fashion Secrest’s result that the IOS method does not truncate closed channels but rather employs a closure relation to sum over all rotor states. The general CS effective cross section formula for relaxation processes is used, along with the IOS approximation to the CS T matrix, to derive the general IOS effective cross section. It is then observed that this cross section can be factored into a finite sum of ’’spectroscopic coefficients’’ Fn(j′aj′b‖jajb ‖L) and ’’dynamical coefficients’’ QL(k). The Fn(j′aJ′b‖jajb ‖L) can be calculated once and tabulated since they do not depend at all on the particular system considered. The QL(k) can be shown to equal the integral inelastic cross section for the transition j=0 to j=L, so that if these cross sections are evaluated, either theoretically or experimentally, other types of cross sections can be computed without any further dynamical calculations. In principle, the factorization permits one to calculate other types of cross sections if any one type of cross section has been obtained by some procedure. The functional form can also be used to compact data. This formalism has been applied to calculate pressure broadening for the systems HD–He, HCl–He, CO–He, HCN–He, HCl–Ar, and CO2–Ar. In order to test the IOS approximation, comparisons have been made to the CS results, which are known to be accurate for all these systems, as well as to several exact close coupling, semiclassical, and experimental values for some of the systems. The IOS approximation is found to be very accurate whenever the rotor spacings are small compared to the kinetic energy, provided closed channels do not play too great a role. For the systems CO–He, HCN–He, and CO2–Ar, these conditions are well satisfied and the IOS is found to yield results accurate to within 10%–15%.
Molecular Rydberg states. XI. Quantum defect analogies between molecules and rare gases
Authors: Wang H. T. , Felps W. S. , Findley G. L. , Rau A. R. P. , McGlynn S. P.
Published: February 2003

The s and d Rydberg series of hydrogen iodide and methyl iodide are reported. These series are assigned using analogies to the corresponding series in xenon. It is shown that a comparison between molecular spectra and pertinent atomic data provides a facile assignment technique for molecular Rydberg spectra. Using the phase amplitude method, the Rydberg data are analyzed in an attempt to provide information on the residual atomic and molecular potentials and to categorize them qualitatively as attractive/repulsive, long range/short range. It is shown that, for l?2, the centrifugal barrier inhibits ingress of the Rydberg electron into the core and that the molecule is effectively spherically symmetric.
Electronic structure of small metal clusters. I. Anions of Be2, Be3, and Be4
Authors: Jordan Kenneth D. , Simons Jack
Published: February 2003

A b initio calculations have been carried out for Be, Be2, Be3, Be4, and their anions. Whereas Be− is unstable with respect to electron detachment, Be2, Be3, and Be4, posses stable negative ions. The electron affinity increases with cluster size as would be expected from simple perturbation theory considerations.
Use of nitroxide spin labels in studies of solvent–solute interactions
Authors: Bates Richard D. , Drozdoski Walter S.
Published: February 2003

Complexities imposed on the studies of dynamic polarization of solvent nuclei by the three-line ESR spectrum of solute nitroxide radicals are examined. These include (1) the field dependence of proton polarizations, (2) the unequal magnitude of the polarizations at frequencies corresponding to the nitroxide radical peaks, and (3) the radical concentration dependence of the extrapolated enhancements. These features are analyzed with respect to existing models and with respect to a new mathematical model based on an exchange interaction that couples radicals in different 14N spin states. This model successfully accounts for the nonlinear extrapolation of enhancements as a function of reciprocal radical concentration. The model is tested experimentally using samples of 4-hydroxy-2,2,6,6-tetramethyl piperid-1-yloxy free radical in benzene, with both DNP and relaxation data used in the analysis.
Centrin4p, a Novel Mammalian Centrin Specifically Expressed in Ciliated Cells
Authors: Gavet Olivier , Alvarez Chantale , Gaspar Patricia , Bornens Michel
Published: February 2003

Centriole assembly plays an important role in centrosome duplication during the cell cycle and is a prerequisite for cilia formation during the differentiation of ciliated cells. In spite of numerous investigations, the molecular machinery that governs centriole/basal body formation remains enigmatic. Recent reports suggest that the ubiquitously expressed mammalian centrins, centrin2p and centrin3p, could be involved in the centriole duplication process. To better understand the specific functions of these proteins, we performed a systematic search for novel mammalian centrins. We isolated a cDNA and the corresponding gene coding for a novel murine centrin, centrin4p, which is more closely related to centrin2p. Like centrin2p, centrin4p accumulates to centrioles and procentrioles when ectopically expressed in HeLa cells. However, centrin4p possesses two splice variants that do not localize to centrioles, suggesting a posttranscriptional regulation mechanism. We also observed that centrin4p does not share the same centriolar targeting properties with centrin2p and 3p, indicating that these proteins could recognize different centriolar partners. Centrin4 mRNA possesses a restricted expression profile and is only detected in brain, kidney, lung, and ovary. In brain, centrin4p is exclusively expressed in ependymal and choroidal ciliated cells where it is localized to basal bodies. Together, our present data suggest that centrin4p could be more specifically involved in basal bodies assembly or in a subsequent step of ciliogenesis.
Sub‐contractor and customer sourcing and the occurrence of disturbances in firms’ inbound and outbound logistics flows
Authors: Svensson Göran
Published: February 2003

This research is based on a mail survey in the Swedish vehicle industry. It is concluded that the sub‐contractor and customer sourcing in the firms’ inbound and outbound logistics flows differ from each other. Furthermore, that there is no association between the sub‐contractor and customer sourcing in the firms’ inbound and outbound logistics flows. Finally, there is in part an association between the sub‐contractor and customer sourcing, and the occurrence of quantitative and qualitative disturbances in firms’ inbound and outbound logistics flows.
Presence of Replicating Virus in Recombinant Hepadnavirus Stocks Results from Recombination and Can Be Eliminated by the Use of a Packaging Cell Line
Authors: Klöcker Uta , Oberwinkler Heike , Kürschner Timo , Protzer Ulrike
Published: February 2003

Mutant hepatitis B viruses are useful tools to study the viral life cycle and viral pathogenesis. Furthermore, recombinant hepatitis B viruses are candidate vectors for liver-directed gene therapy. Because wild-type viruses present in recombinant or mutant virus stocks may falsify experimental results and are detrimental for a viral vector, we investigated whether and to what extent wild-type virus is present in recombinant virus stocks and where it originates from. We took advantage of the duck model of hepatitis B virus infection which allows very sensitive detection of replication-competent viruses by infection of primary duck hepatocytes or of ducklings in vivo. Recombinant hepatitis B virus stocks contained significant amounts of wild-type viruses, which were most probably generated by homologous recombination between plasmids containing homologous viral sequences. In addition, replication-competent viral genomes were reconstituted from plasmids which contained replication-deficient but redundant viral sequences. Using a stable cell line for packaging of deficient viral genomes, no wild-type virus was detected, neither by infection of primary hepatocytes nor in vivo.
Jak1 deficiency leads to enhanced Abelson-induced B-cell tumor formation
Authors: Sexl Veronika , Kovacic Boris , Piekorz Roland , Moriggl Richard , Stoiber Dagmar , Hoffmeyer Angelika , Liebminger Rita , Kudlacek Oliver , Weisz Eva , Rothammer Kristen , Ihle James N.
Published: February 2003

The Janus kinase Jak1 has been implicated in tumor formation by the Abelson oncogene. In this study we show that loss of Jak1 does not affect in vitro transformation by v-abl as defined by the ability to induce cytokine-independent B-cell colony formation or establishment of B-cell lines. However, Jak1-deficient, v-abl–transformed cell lines were more tumorgenic than wild-type cells when transplanted subcutaneously into severe combined immunodeficient (SCID) mice or injected intravenously into nude mice. Jak1 deficiency was associated with a loss in the ability of interferon-γ (IFN-γ)to induce growth arrest and/or apoptosis of v-abl–transformed pre-B cells or tumor growth in SCID mice. Moreover, IFN-γ mRNA could be detected in growing tumors, and tumor cells explanted from SCID mice had lost the ability to respond to IFN-γ in 9 of 20 cases, whereas the response to interferon-α (IFN-α) remained intact. Importantly, a similar increase in tumorgenicity was observed when IFN-γ–deficient cells were injected into SCID mice, identifying the tumor cell itself as the main source of IFN-γ. These findings demonstrate that Jak1, rather than promoting tumorgenesis as previously proposed, is critical in mediating an intrinsic IFN-γ–dependent tumor surveillance.
Constitutive exclusion of Csk from Hck-positive membrane microdomains permits Src kinase-dependent proliferation ofTheileria-transformed B lymphocytes
Authors: Baumgartner Martin , Angelisová Pavla , Setterblad Niclas , Mooney Nuala , Werling Dirk , Horejsı́ Václav , Langsley Gordon
Published: February 2003

Infection of bovine T cells and B cells with the intracellular protozoan parasite Theileria parva induces a transformed phenotype with characteristics comparable to leukemic cells. The transformed phenotype reverts on drug-induced parasite death, and the cured lymphocytes acquire a resting phenotype and eventually die by apoptosis if not further stimulated. Here, we show that both lymphocyte proliferation and activation of the transcription factor AP-1 are mediated by Src-family protein tyrosine kinases (PTKs) in a parasite-dependent fashion. Src-family PTKs are known to be present in glycolipid-enriched microdomains (GEMs), also called lipid rafts, and to be negatively regulated by PTK Csk complexed to tyrosine-phosphorylated transmembrane adapter protein PAG (phosphoprotein associated with GEMs) also called Cbp (Csk-binding protein). We, therefore, purified GEMs from proliferating infected B cells and from growth-arrested cells that had been drug-cured of parasites. Proliferation arrest led to a striking increase of PAG/Cbp expression; correspondingly, the amount of Csk associated with PAG/Cbp in GEMs increased markedly, whereas PTK Hck accumulation in GEM fractions did not alter on growth arrest. We propose thatTheileria-induced lymphocyte proliferation and permanent activation of Hck stems from down-regulation of PAG/Cbp and the concomitant constitutive loss of the negative regulator Csk from the GEMs of transformed B cells.
All-trans-retinoic acid induces CD52 expression in acute promyelocytic leukemia
Authors: Li Shi-Wu , Tang Dongqi , Ahrens Kim P. , She Jin-Xiong , Braylan Raul C. , Yang Lijun
Published: February 2003

It is well known that all-trans-retinoic acid (ATRA) can induce myeloid cell differentiation in acute promyelocytic leukemia (APL) cells. In this study, we found that ATRA treatment of the APL cell line NB4 induced the expression of CD52, both at transcriptional and translational levels. CD52 is a 21- to 28-kDa nonmodulating cell surface glycosylphosphatidylinositol-linked glycoprotein expressed on lymphocytes and monocytes, but not in human myeloid cells. The ATRA-dependent induction of CD52 expression was not observed in non-promyelocytic leukemia cell lines such as K562, U937, and HL-60, suggesting that induction of CD52 by ATRA may be specific to leukemic cells that express promyelocytic leukemia–retinoic acid receptor α (PML-RARα) or are at the promyelocytic stage of myeloid development. Antibodies against CD52 are used therapeutically against lymphocytes in certain leukemias and in patients undergoing transplantation. An ATRA-induced high level of CD52 expression might potentially serve as a novel therapeutic target in treatment of APL.
Enforced expression of CUL-4A interferes with granulocytic differentiation and exit from the cell cycle
Authors: Li Binghui , Yang Feng-Chun , Clapp D. Wade , Chun Kristin T.
Published: February 2003

The cullin family of proteins is involved in the ubiquitin-mediated degradation of cell cycle regulators. Relatively little is known about the function of the CUL-4A cullin, but its overexpression in breast cancer suggests CUL-4A might also regulate the cell cycle. In addition, since other cullins are required for normal development, we hypothesized that CUL-4A is involved in regulating cell cycle progression during differentiation. We observed that CUL-4A mRNA and protein levels decline 2.5-fold during the differentiation of PLB-985 myeloid cells into granulocytes. To examine the significance of this observation, we overexpressedCUL-4A in these cells and found that modest (< 2-fold), enforced expression of CUL-4A attenuates terminal granulocytic differentiation and instead promotes proliferation. This overexpression similarly affects the differentiation of these cells into macrophages. We recently reported that nearly one half of CUL-4A+/− mice are nonviable, and in this report, we show that the viable heterozygous mice, which have reducedCUL-4A expression, have dramatically fewer erythroid and multipotential progenitors than normal controls. Together these results indicate that appropriate CUL-4A expression is essential for embryonic development and for cell cycle regulation during granulocytic differentiation and suggest this gene plays a broader role in hematopoiesis. Since enforced CUL-4A expression does not alter the cell cycle distribution of uninduced cells but dramatically increases the proportion of induced cells that remains in S-phase and reduces the proportion that accumulates in G0/G1, our results show that thisCUL-4A regulatory function is interconnected with differentiation, a novel finding for mammalian cullins.
Unmutated immunoglobulin variable heavy-chain gene status remains an adverse prognostic factor after autologous stem cell transplantation for chronic lymphocytic leukemia
Authors: Ritgen Matthias , Lange Alexandra , Stilgenbauer Stephan , Döhner Hartmut , Bretscher Christian , Bosse Heidi , Stuhr Ariane , Kneba Michael , Dreger Peter
Published: February 2003

An unmutated germ line configuration of the immunoglobulin variable heavy-chain gene (VH) has emerged to be a crucial adverse prognostic factor in chronic lymphocytic leukemia (CLL) under conventional treatment. The purpose of the present study was to investigate whether the VH mutational status retains its prognostic value in CLL also in the setting of autologous stem cell transplantation (SCT). Therefore, we investigated the mutational status in 58 patients with CLL who underwent myeloablative radiochemotherapy with SCT. Rearranged VH genes were analyzed by multiplex polymerase chain reaction (PCR) and direct sequencing using FR1 family–specific primers and JH consensus primers. Twenty patients (34%) showed less than 98% homology compared with germ line VH sequences and were considered as mutated, whereas 38 patients (66%) had an unmutated VH status (median mutational rate of 0%; range, 0%-1.7%). An unmutated VHconfiguration was strongly correlated with the presence of short lymphocyte doubling time (P = .003) and high lymphocyte count (P = .005). Time to clinical relapse and time to recurrence of monoclonal B cells as assessed by consensus IgH CDR3 PCR was significantly shorter in the group with unmutated VH genes (2-year probability 19% versus 0%,P = .0008, and 34% versus 9%, P = .0006, respectively). These results show that in CLL, an unmutated VH gene status of the tumor clone remains an adverse prognostic factor after SCT. Nevertheless, the hitherto only 3 deaths and the median treatment-free interval of 49 months in the unmutated cohort suggest a beneficial effect of SCT for this high-risk population in comparison to conventional treatment.
Oscillation between B-lymphoid and myeloid lineages in Myc-induced hematopoietic tumors following spontaneous silencing/reactivation of the EBF/Pax5 pathway
Authors: Yu Duonan , Allman David , Goldschmidt Michael H. , Atchison Michael L. , Monroe John G. , Thomas-Tikhonenko Andrei
Published: February 2003

B lymphomagenesis is an uncontrolled expansion of immature precursors that fail to complete their differentiation program. This failure could be at least partly explained by inappropriate expression of several oncogenic transcription factors, such as Pax5 and Myc. Both Pax5 and c-Myc are implicated in the pathogenesis of non-Hodgkin lymphomas. To address their role in lymphomagenesis, we analyzed B-cell lymphomas derived from p53-null bone marrow progenitors infected in vivo by a Myc-encoding retrovirus. All Myc-induced lymphomas invariably maintained expression of Pax5, which is thought to be incompatible with terminal differentiation. However, upon culturing in vitro, several cell lines spontaneously down-regulated Pax5 and its target genes CD19, N-Myc, and MB1. Unexpectedly, other B-cell markers (eg, CD45R) were also down-regulated, and markers of myeloid lineage (CD11b and F4/80 antigen) were acquired instead. Moreover, cells assumed the morphology reminiscent of myeloid cells. A pool of F4/80-positive cells as well as several single-cell clones were obtained and reinjected into syngeneic mice. Remarkably, pooled cells rapidly re-expressed Pax5 and formed tumors of relatively mature lymphoid phenotype, with surface immunoglobulins being abundantly expressed. Approximately half of tumorigenic single-cell clones also abandoned myeloid differentiation and gave rise to B lymphomas. However, when secondary lymphoma cells were returned to in vitro conditions, they once again switched to myeloid differentiation. This process could be curbed via enforced expression of retrovirally encoded Pax5. Our data demonstrate that some Myc target cells are bipotent B-lymphoid/myeloid progenitors with the astonishing capacity to undergo successive rounds of lineage switching.
Oxidized phospholipids in oxidized low-density lipoprotein down-regulate thrombomodulin transcription in vascular endothelial cells through a decrease in the binding of RARβ-RXRα heterodimers and Sp1 and Sp3 to their binding sequences in the TM promoter
Authors: Ishii Hidemi , Tezuka Tsuyoshi , Ishikawa Hiroyuki , Takada Kimihiko , Oida Koji , Horie Shuichi
Published: February 2003

The present work investigated the mechanism for down-regulation of thrombomodulin (TM), an anticoagulant glycoprotein, on cultured umbilical vein endothelial cells (HUVECs) exposed to lipid extracts from oxidized low-density lipoprotein (ox-LDL). HUVECs exposed to phospholipid extracts, but not to free cholesterol, triglyceride, or cholesterol ester, isolated from ox-LDL reduced TM mRNA levels to nearly the same extent as native ox-LDL. Oxidized 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphocholine (ox-PAPC), but not native PAPC or a reduced form of ox-PAPC, markedly decreased TM mRNA levels. The apparent half-life (t 1/2 = 2.7 hours) of TM mRNA in control cells was not significantly different from that in cells exposed to ox-LDL or ox-PAPC. TM mRNA levels were regulated by transcriptional activation via a retinoid receptor β (RARβ). The binding activities of nuclear proteins from HUVECs treated with ox-LDL or ox-PAPC to the DR4 or stimulatory protein 1 (Sp1) sequence in the TM promoter were significantly reduced with decreased expression of RARβ, retinoid X receptor α (RXRα), Sp1, and Sp3 in the nuclei. The promoter activity in HUVECs transfected with a reporter plasmid expressing the TM promoter with targeted deletions in the DR4 and Sp1 binding elements was decreased to about 20% of that with the wild-type construct. Treatment of the cells with ox-PAPC had no additional effect on the promoter activity. These results suggest that oxidized phospholipids in ox-LDL inhibit transcription of the TM gene in HUVECs by inhibiting the binding of RARβ-RXRα heterodimer and Sp, including Sp1 and Sp3, to the DR4 element and Sp1 binding element, respectively, in the TM promoter with reduced expression of RARβ, RXRα, and Sp1 and Sp3 in the nuclei.
Synthesis and analysis of aminochromes by HPLC‐photodiode array. Adrenochrome evaluation in rat blood
Authors: Remião Fernando , Milhazes Nuno , Borges Fernanda , Carvalho Félix , Bastos Maria L. , Lemos‐Amado Francisco , Domingues Pedro , Ferrer‐Correia A.
Published: February 2003

The catecholamine oxidation process induces cardiotoxicity and neurotoxicity. Catecholamines can oxidize to aminochromes through autoxidation or by enzymatic or non‐enzymatic catalysis. Although some toxic effects seem to be related to the formation of aminochromes there is still scarce information concerning the identification and evaluation of these compounds in in vivo models. In this study five catecholamines were oxidized to their respective aminochromes: adrenaline/adrenochrome; noradrenaline/noradrenochrome; dopa/dopachrome; dopamine/dopaminochrome; and isoproterenol/isoprenochrome. The evaluation of the catecholamines oxidation profile was performed by HPLC with photodiode array detection and using either enzymatic (tyrosinase) or non‐enzymatic [Ag2O, CuSO4, NaIO4 and K3Fe(CN)6] catalytic systems. The NaIO4 was found to be the most efficient oxidant of catecholamines. An isocratic reverse‐phase HPLC method was developed to analyse each pair of catecholamine–aminochrome. The analytical system was then applied to the detection of adrenochrome in rat blood at 490 nm. Thus, adrenochrome was administered i.p. to rats and its concentration in whole blood was monitored after 5, 15 and 25 min. Blood treatment for adrenochrome evaluation consists of an acidification for protein precipitation followed by a rapid neutralization. The results showed a rapid decrease of adrenochrome concentration in blood after its administration. The adrenochrome present in blood was characterized by UV and tandem mass spectrometry. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis and Nonlinear Optical Absorption of Novel Porphyrin–Osmium‐Cluster Complexes
Authors: Yang Guo Ying , Ang Siau Gek , Chng Leng Leng , Lee Yiew Wang , Lau Ernest Wei‐Pin , Lai Kin Seng , Ang How Ghee
Published: February 2003

Reaction of azido(tetra‐p‐tolylporphyrinato)indium(III) [TTPInN3] and [Os3(μ‐H)2(CO)10] in toluene at 80 °C overnight gave two major products, complexes 1 and 2. Complex 1 had an axial bridge of “NH”, while 2 had an axial bridge of “N” between the porphyrin and osmium cluster moieties. Complex 1 could be converted to 2 when refluxed in toluene. These two novel porphyrin–osmium clusters are the first axially linked porphyrin–metal cluster complexes. UV/Vis spectroscopy revealed the significant ground state electronic perturbation in the capped complex 2, demonstrating that the remarkable electronic interaction of the moieties within the molecule was achieved by this special structural arrangement. In addition, the electrochemistry of 1 and 2 were investigated and their oxidation current voltage curves are similar to those of indium(III)–porphyrins with a metal–metal σ bond such as [TPPInRe(CO)5] (TPP=tetraphenylporphyrin). The two new molecules also exhibit large nonlinear optical absorption at 532 nm with a ns pulse laser and are potential optical limiting materials for sensor protection in the visible region.
Wasser als Lösungsmittel: Koordinationskatalyse
Authors: Fuhrmann Hans , Dwars Torsten , Oehme Günther
Published: February 2003

Wasser galt bisher als bevorzugtes Lösungsmittel in anorganisch‐analytischen Reaktionen und in der Biokatalyse. Mit der Entwicklung der homogenen Koordinationskatalyse und deren Übertragung in Multiphasensysteme wurde Wasser als polare Phase interessant. Voraussetzung war die Synthese wasserlöslicher, katalytisch wirksamer Komplexe, die durch einfache Abtrennung der wässrigen Phase in den Prozess zurückgeführt werden können. Für eine Reihe organischer Synthesen wurden in Wasser Vorteile bezüglich Aktivität und Selektivität beobachtet. Außerdem bietet Wasser besondere Möglichkeiten im supramolekularen Bereich, und es ist als Medium für trägerfixierte Katalysatoren geeignet. Wasser im superkritischen Zustand zeigt ein völlig neuartiges Verhalten als Lösungsmittel und als Reaktionspartner. Ein Vorteil des Wassers für die industrielle Nutzung liegt in der leichten Zugänglichkeit und der Umweltverträglichkeit.
Der natürliche Chlor‐Zyklus zwischen Boden und Atmosphäre
Authors: Jaenicke Lothar
Published: February 2003

Wir kennen die Kreisläufe von Kohlenstoff, Stickstoff und auch Schwefel in der Natur, durch die gebundene Elemente wieder zu neuer Nutzung zurückgeführt werden. Ihr Prinzip ist, Unlösliches zu lösen, Unflüchtiges zu verflüchtigen, zu zerlegen und durch Oxidation oder Reduktion in geo‐ oder biochemischen Prozessen umzuwandeln, so dass es über die Biosphäre wieder verfügbar wird:
Neuartige Metaboliten aus dem Schönfuß‐Röhrling und verwandten Bitterpilzen
Authors: Feil Sylvia
Published: February 2003

Unter den Röhrenpilzen heben sich einige Arten der Gattung Boletus durch ihren bitteren Geschmack hervor. Allein schon ein Gallenröhrling, Tylopilus felleus, macht eine Pilzmahlzeit ungenießbar.
Cover Picture: A Microscopic, Continous, Optical Monitor for Interstitial Electrolytes and Glucose (ChemPhysChem 2/2003)
Authors: Tohda Koji , Gratzl Miklós
Published: February 2003

The cover picture shows one possible path of evolution of glucose sensing from a potentiometric glucose electrode through an analogous optical detector to a microscopic in vivo glucose monitor. An optical multisensing bar (called the “sliver sensor”) is being developed in Prof. Miklos Gratzl's laboratory at Case Western Reserve University, to support NASA's Space program. The tiny sliver contains color‐changing compartments that respond to pH, K+, and glucose levels in the interstitial fluid under the skin surface. The sliver, once inserted into the skin parallel to the surface, will be interrogated by a watchlike device placed on top of the skin. Reference compartments (only one being shown on the cover) will be used to subtract color changes due to skin absorption and scattering, so that the real color of the actual sensing pads can be reconstructed. The approach is an example of very simple telemetry across the skin. Since no wires or optical fibers cross the skin, no risk of track infection exists.
Effect of PUFA at sn‐2 position in dietary triacylglycerols on the fatty acid composition of adipose tissues in non‐ruminant farm animals
Authors: Scheeder Martin R. L. , Gumy Didier , Messikommer Ruth , Wenka Caspar , Lambelet Pierre
Published: February 2003

The influence of the distribution of polyunsaturated fatty acids on the glycerol backbone of dietary triacylglycerols on the fatty acid profile of adipose tissue and muscle phospholipids was investigated in growing‐finishing pigs (48) and broiler chicken (84). The animals were fattened on barley/soybean meal diets supplemented with a blend of soybean oil and beef tallow, either in the ratio 3:1 w/w (high‐PUFA) or 1:3 w/w (low‐ PUFA). Part of the high‐ and low‐PUFA blends was chemically interesterified to randomly distribute all fatty acids over the three positions of the glycerol. Thus, two sets of diets of identical overall fatty acid composition, but differing in the distribution of fatty acids in the triacylglycerols, were fed. Growth performance and carcass composition were neither affected by fatty acid composition nor by randomisation of dietary fats in either animal species. Apparent digestibility of energy was slightly lower in pigs fed the low‐PUFA blends. Fatty acid profile of subcutaneous fat of pigs and broilers as well as of internal body fat (lamina subserosa) and muscle phospholipids of pigs varied according to the dietary fatty acid composition but was not affected by randomisation of dietary fats. These findings are explained in terms of the hydrolysis of TAG during transport of lipids from enterocytes to adipose tissue cells and the continuous lipolysis and re‐esterification of fatty acids that take place in adipose tissue cells.
Synthesis and Absolute Configuration of (−)‐Subersic Acid, a Sponge‐Derived, Terpenoidal Inhibitor of Human 15‐Lipoxygenase
Authors: Tanada Yoshihisa , Mori Kenji
Published: February 2003

(−)‐Subersic acid (1), a new derivative of p‐hydroxybenzoic acid in which the m‐position is substituted with a bicyclic diterpenoid, was synthesized from (S)‐3‐hydroxy‐2,2‐dimethylcyclohexanone and p‐hydroxybenzoic acid. The stereochemistry of this sponge‐derived inhibitor of human 15‐lipoxygenase was established as (5R,10R)‐1. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Highly Enriched Mixtures of Methohexital Stereoisomers by Palladium‐Catalyzed Allylation and Their Anaesthetic Activity
Authors: Brunner Henri , Ittner Karl‐Peter , Lunz Dirk , Schmatloch Stefan , Schmidt Thomas , Zabel Manfred
Published: February 2003

The stereoselective Pd‐catalyzed allylation of MBA [5‐(2′‐hex‐3′‐ynyl)‐1‐methylbarbituric acid] gives the commercial injection narcotic methohexital, which exists as four isomers: two diastereomeric pairs of enantiomers. The isomer composition produced depends on three stereochemical parameters: catalyst control, substrate control, and kinetic resolution. Judicious choice of these parameters allowed the synthesis of methohexital samples with greatly differing isomer compositions, and these samples were investigated with respect to their anaesthetic doses in rats. Some isomer compositions obtained were much more active than the commercially used drug and showed fewer side effects. As a consequence of the determination of the absolute configuration of the methohexital (SbRh) isomer, the unknown configuration of the trade product, the so‐called α‐racemate, can be established as (RbSh) and (SbRh). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Electroimmobilization of MAO into a Polypyrrole Film and Its Utilization for Amperometric Flow Detection of Antidepressant Drugs
Authors: Vela M. H. , de Jesus Djane S. , Couto Cristina M. C. M. , Araújo Alberto N. , Montenegro M. C. B. S. M.
Published: February 2003

The preparation of a biosensor based on the enzymatic immobilization in polypyrrole polymer for the detection of antidepressant drugs is described. The enzyme monoamine oxidase (MAO) was immobilized by electropolymerization of pyrrole around a platinum electrode, at a constant potential of +0.75 V (vs. Ag/AgCl) in such a way to obtain a membrane thickness, which was constant and equal to 100 mC/cm2. The biosensor was obtained from a 0.1 M KCl saline solution containing pyrrole at a concentration equal to 0.4 M and 2.5 mU/mL of MAO. The biosensor was adapted to a continuous flow injection analysis system (FIA) with the amperometric detection of hydrogen peroxide produced by enzymatic reaction carried out at a potential of +0.7 V (vs. Ag/AgCl), pH 7.4 and temperature of 37 °C. In optimized flow conditions, the biosensor presented an analytical response for fluoxetine in the interval between 0.67 and 4.33 mM, with a detection limit of 0.10 mM. The analytical use of the biosensor developed was evaluated through analysis of commercial pharmaceutical products containing fluoxetine, available on the Portuguese market. The amperometric flow results obtained do not differ significantly from the values resulting from analysis of the same products by the method proposed by the US Pharmacopeia, with sampling rates of 20–25 samples/hour.
What type of enterprise forges close links with universities and government labs? Evidence from CIS 2
Authors: Mohnen Pierre , Hoareau Cathy
Published: February 2003

This paper tries to uncover some of the economic factors that encourage firms to seek information from universities and government labs or to collaborate with these institutions. We exploit the information contained in the second Community Innovation Surveys (CIS2) for France, Germany, Ireland and Spain. We estimate an ordered probit model on the importance of knowledge sourcing from universities and government labs controlling for selection bias, and a trivariate probit model explaining the decisions to innovate, collaborate in innovation, and in particular collaborate with universities and government labs. R&D‐intensive firms and radical innovators tend to source knowledge from universities and government labs but not to cooperate with them directly. Outright collaborations in innovation with universities and government labs is characteristic of large firms, firms that patent or those that receive government support for innovation. Members of an enterprise group tend to cooperate in innovation but not directly with universities or government labs. Copyright © 2003 John Wiley & Sons, Ltd.
Trophic level isotopic enrichment of carbon and nitrogen in bone collagen: case studies from recent and ancient terrestrial ecosystems
Authors: Bocherens H. , Drucker D.
Published: February 2003

Prey‐predator collagen enrichment values for carbon and nitrogen isotopic compositions are investigated. New enrichment values are given for the well‐monitored ecosystem of Bialowieza primeval forest (Poland) for lynx and wolf. The impact of using different approximations in calculating such enrichment values is discussed. Several case studies of ancient vertebrate communities from Upper Palaeolithic sites in southwestern France are presented to check whether the enrichment values estimated for these past ecosystems are consistent with those measured in well‐monitored modern ecosystems. The use of ranges of values rather than average ones is recommended, tentatively 0 to 2‰ for δ13C and 3 to 5‰ for δ15N. Copyright © 2003 John Wiley & Sons, Ltd.
Development of the morphology and crystalline state due to hybridization of reinforced toughened nylon containing a liquid‐crystalline polymer
Authors: Pisharath Sreekumar , Wong Shing‐Chung
Published: February 2003

A hybrid composite consisting of rubber‐toughened nylon‐6,6, short glass fibers, and a thermotropic liquid‐crystalline polymers (LCP) was investigated by the LCP content being varied. The thermal behavior, morphology, and crystallization behavior due to hybridization were studied by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and wide‐angle X‐ray scattering (WAXS). DSC results indicated that the crystallinity of the glass‐fiber‐reinforced toughened nylon‐6,6 was reduced by LCP addition, particularly 5–10 wt % LCP. DMA data showed that the miscibility between the blended components was maximum at the 5 wt % LCP composition, and the miscibility decreased with increasing LCP content. SEM photomicrographs revealed information consistent with the thermal behavior on miscibility. It was also observed that the 10 wt % LCP composition showed predominantly an amorphous character with FTIR and WAXS. WAXS results indicated that LCP hybridization increased the interplanar spacing of the hydrogen‐bonded sheets of the nylon crystals rather than the spacing between the hydrogen‐bonded chains. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 549–559, 2003
Flachheitsbasierte Steuerung eines Timoshenko‐Balkens
Authors: Rudolph J. , Woittennek F.
Published: February 2003

An open loop control for a clamped Timoshenko beam, driven by a boundary torque, is presented. With the proposed method finite time transitions between two steady states can be achieved. The solution of the PDE is obtained using Mikusiński operators. The time dependent functions corresponding to the operators have compact support and can be represented using infinite series. When parametrizing the system by a flat output, the system trajectories can be written as definite integrals.
Overlapping effects and motional narrowing in molecular band shapes: Application to the Q branch of HDa)
Authors: Bonamy Jeanine , Bonamy Lionel , Robert Daniel
Published: February 2003

A new formulation of the theory of strong overlapping effects in molecular line broadening is presented in terms of the intermolecular potential. This formulation takes into account the vibrational degrees of freedom and includes in an acceptable form the close collisions. A detailed analysis of such effects is carried out for the motional narrowing arising in the Q branch of HD at sufficiently high densities. A very good consistency is obtained between the experimental data and the present calculation at room and low temperatures. The nonadditivity effects in infrared absorption and anisotropic Raman overlapping lines treated in the general frame of this paper may also be easily calculated when required.
The adsorption of benzene on the Pt(111) surface studied by low-energy electron diffraction intensity measurements and quantitative Auger electron spectroscopy
Authors: Stair P. C. , Somorjai G. A.
Published: February 2003

Benzene, when chemisorbed on the Pt(111) crystal face forms an ordered metastable ‖40 4−2‖ surface structure which transforms, slowly, to a stable ‖40 5−2‖ surface structure. A complete set of intensity–voltage (I vs V) curves are presented in the appendix to aid in solving the surface structures of this complex organic molecule. The size of the unit cells and the larger than monolayer carbon surface concentrations (determined by quantitative Auger spectroscopy) indicate that most of the adsorbed benzene molecules are inclined at an angle to the surface. The similarity of the (I–V) profiles for the same diffraction beams from the two structures indicate that the carbon–platinum layer spacing changes very little during the order–order transformation.
The role of the dipole–dipole interaction in the energy transfer process in aromatic solutions
Authors: Chalzel A.
Published: February 2003

Fluorescence quantum yield for neat benzene and neat and dilute toluene and energy transfer from toluene and benzene to PBD (2-phenyl-5- (4-biphenylyl) -1,3,4-oxadiazole) have been measured in the 20–160 °C temperature range. The measurements were analyzed assuming Stern–Volmer kinetics. The results can be explained by assuming that the main mechanism of energy transfer in these systems is the diffusion assisted resonance dipole–dipole interaction, which can get saturated in those systems because of the large excitation diffusion rates. At higher temperatures (T?110 °C) short range or collisional interactions begin to play a more important role.
The effects of hydrodynamic interactions on translational and rotational relaxation
Authors: Montgomery John A. , Berne Bruce J.
Published: February 2003

A theory of coupled translational and rotational relaxation in solution including the effects of hydrodynamic interaction is presented. The translational, translational–rotational, and rotational diffusion tensors are computed using the method of hydrodynamic reflections. The correlation functions Clm(t) =〈Ylm*[u(0)] Ylm[u(t)]〉 and Clm(q,t) =〈exp iq⋅[r(t)−r(0)] Ylm*[u(0)] Ylm[u(t)]〉 are found from a coupled translational–rotational diffusion equation. Clm(t) is shown to reduce to the Debye result under conditions relevant to magnetic resonance experiments. The concentration dependence of the rotational diffusion coefficient is calculated and compared with experiment. The failure of the results to account for the dynamical correlations seen in recent NMR studies of protein solutions by Koenig and co-workers is discussed.
Temperature dependence of the rate of reaction H+NO+M→HNO+M for M=H2 and the relative third body efficiencies of NO and H2
Authors: Oka K. , Singleton D. L. , Cvetanović R. J.
Published: February 2003

In our previous study of the HNO* (1A″) luminescence in gaseous mixtures of H2, NO, and Hg illuminated by intensity-modulated 253.7 nm light, we have observed two distinct rates of luminescence decay. Involvement of two distinct HNO* precursors, presumably H atoms and HgH radicals, was therefore indicated. The slower of the two luminescence decay rates provided the 298 K value of the rate of reaction H+NO+M→HNO+M, for M=H2. In the present study a more detailed analysis has been made of the potential effects of secondary processes in this reaction system on the measured values of the rate constants. It has been found that intensity of luminescence is approximately proportional to mole fraction of H2 and inversely proportional to total pressure and the interference from secondary processes is at a minimum at large NO mole fractions or high total pressures. Under these conditions the following values of the rate constants were obtained at 298 K: kH+NO+H2=1.55×1010 and kH+NO+NO=1.91×1010 l2 mol−2 s−1; i.e., NO appears to be a somewhat more efficient third body than H2 for the H+NO combination reaction. The overall uncertainty in the former value is estimated at about ±15% and in the latter at about ±20%. In the temperature range 298–477 K the results for the H+NO+H2 reaction fit the Arrhenius expression kH+NO+H2= (4.61±0.16) ×109 exp(722±23 cal mol−1/RT) l2 mol−2 s−1.
Vibrational relaxation times of F2–He and Ar, H2–He, and D2–He. II
Authors: Cady W. A. , Diebold Alain C.
Published: February 2003

A three-dimensional semiclassical (impact parameter) theory for the calculation of vibrational lifetimes is developed and compared with the high temperature results from shock tube experiments on the systems F2–Ar, F2–He, H2–He, and D2–He. The formalism is centered on the average change in vibrational quantum number with the effect of rotation on the vibrational relaxation treated by using a sudden or impulselike approximation. A comparison of these results with those from collinear and other theories shows this treatment to be more accurate and a more realistic description of the process. At the same time the formalism is developed to maintain an ease of calculation and a simple form analogous to that of the collinear theories so that experimental results can be readily correlated with the theory.
Dielectric dispersion and dielectric friction in electrolyte solutions. I.
Authors: Hubbard J. , Onsager L.
Published: February 2003

A self-consistent, kinetic theory of ion–solvent interactions is developed within the framework of continuum mechanics. It is shown that the hydrodynamic coupling between viscous momentum transport and dielectric relaxation leads not only to a theory of ion mobility but also to a description of the dielectric properties of electrolyte solutions. The concept of kinetic polarization deficiency is introduced, whereby the static permittivity of a solution is reduced from that of the pure solvent by an amount proportional to the product of solvent dielectric relaxation time and low frequency conductivity of the solution. Furthermore, if the viscous and dielectric relaxation times are assumed to be comparable it is demonstrated that ’’deformation inertia’’ should make a significant contribution to the decrement Δε0. Ion mobility is calculated to first order in a coupling parameter which is inversely proportional to the fourth power of the ion radius, the limiting case of zero ion size is analyzed, and general aspects of ion migration are investigated with the aid of the principle of minimum dissipation. Given that the pure solvent has a dispersion characterized by a single Debye relaxation time τD, it is asserted that the solution will, as a consequence of dielectric friction, possess an infinite number of relaxation times extending from τD down to the longitudinal time τL=τD(ε∞/ε0).
Valence and core electron energies in alkyl cadmium compounds from a
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o calculations and photoelectron spectra: Electric field gradients in gas phase Cd compounds
Authors: Bancroft G. Michael , Creber David K. , Basch Harold
Published: February 2003

The Hei and x-ray photoelectron spectra of the valence levels, Cd 4d levels, and other core levels in Me2Cd and Et2Cd have been recorded. The resolved splitting of the Cd 4d levels is attributed to a ligand field (rather than a bonding) effect, and the major part of the splitting is due to the asymmetric C°2 crystal field term which transforms like the electric field gradient. The derived C°2 and C°4 4d terms are as follows: Me2Cd,−0.0225±0.0008 eV and −0.0008±0.0001 eV; Et2Cd,−0.023±0.002 eV and −0.0012±0.0004 eV. The photoelectron results are compared with ab initio self-consistent field (SCF) calculations (employing a large Gaussian orbital basis set) for the Cd atom and Me2Cd complex. The calculation confirms the electrostatic nature of the 4d splitting. In addition, the Cd 4d and C 2s levels both show chemical shifts which are electrostatic in nature, and the Cd 4d: C 2s intensity ratio is in reasonable agreement with that expected if the 4d and 2s orbitals are atomic in nature. Owing to neglect of electronic relaxation, the ground state calculation overestimates both the orbital ionization potentials and the 4d splitting. The calculated value (+20.5 kcal/mole) for the heat of reaction Cd+C2H6→ (CH3)2Cd is in good agreement with the thermochemical value (+17.7 kcal/mole).
Chemiluminescence from Al+O3: Perturbations, populations, and vibrational analysis for the AlO A 2Π–X 2Σ+ transition
Authors: Sayers Michael J. , Gole James L.
Published: February 2003

As a complement to an earlier study of the AlO B 2Σ+–X 2Σ+ emission system, the A 2Πi–X 2Σ+ chemiluminescence resulting from the reaction Al+O3→AlO*+O2 has been investigated. It is found that the constants extracted for the A 2Πi state by McDonald and Innes adequately describe the vibrational structure of this state to high (∼29) vibrational levels, the behavior being indicative of a Morse oscillator. Perturbations previously observed in the X 2Σ+ state are explicitly analyzed in terms of A 2 Π1/2–X 2Σ+ spin–orbit interactions, and a comparison with A 2Π1/2–B 2Σ+ perturbations is made. Approximate populations Nv′ for the A 2Πi vibrational levels are determined; the population distribution is dramatically non-Boltzmann, peaking at an energy just below that corresponding to the v=0 level of the B 2Σ+ state. This peaking is explained in terms of efficient collisional transfer from the A state to the B state.
Simple electrolytes in the mean spherical approximation. III. A workable model for aqueous solutions
Authors: Triolo R. , Blum L. , Floriano M. A.
Published: February 2003

Some improvements in the primitive model of electrolyte solutions are discussed within the framework of the mean spherical approximation. Excellent agreement has been found between experimental and calculated osmotic and activity coefficients of 16 alkali halides in H2O at 25 °C, whenever a density dependent hard core ionic diameter is combined with an adjustable but not density dependent dielectric constant. Promising agreement is also found when Pauling crystallographic radii are used for the ions.
Theoretical calculation of the valence excited states of the AlH molecule
Authors: Pelissier M. , Malrieu J. P.
Published: February 2003

The ground and lowest excited state potential curves of the AlH molecule have been calculated in a double-zeta-plus polarization basis set of Gaussian type orbitals. The core electrons of the Al atom are taken into account through a nonempirical pseudopotential. Large scale CI’s are performed according to the CIPSI technique. The calculated transition energies, bond distances, and force constants are in good agreement with experiment for the observed excited states. Three new states with dissociative or long equilibrium distance potential curves have been identified.