bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective HOESY experiments for stereochemical determinations
Authors: Yemloul Mehdi , Bouguet‐Bonnet Sabine , Ba Lalla Aïcha , Kirsch Gilbert , Canet Daniel
Published: August 2008

Heteronuclear Overhauser effect spectroscopy (HOESY) is a powerful method for tracking geometrical proximities between two heteronuclei (for instance, 1H and 13C, as this will be the case here). The method is based on cross‐relaxation arising from dipolar interactions. Sensitivity permitting, it is applied in the 2D mode yielding all spatial correlations in a single experiment. Whenever sensitivity is not sufficient, it can be applied in the one‐dimensional mode by selectively inverting one particular proton. In that case, it yields, from the carbon‐13 spectrum, remote spatial correlations. The method has been employed here for the discrimination between two possible E or Z isomers in a medium‐size molecule. Copyright © 2008 John Wiley & Sons, Ltd.
CD34 expression is associated with poor survival in pediatric T‐cell acute lymphoblastic leukemia
Authors: van Grotel Martine , van den Heuvel‐Eibrink Marry M. , van Wering Elisabeth R. , van Noesel Max M. , Kamps Willem A. , Veerman Anjo J.P. , Pieters Rob , Meijerink Jules P.P.
Published: August 2008

Background

Children with T‐lineage acute lymphoblastic leukemia (T‐ALL) have an inferior outcome with combination chemotherapy compared to B‐lineage ALL, and still about 30% of the patients relapse within the first 2 years following diagnosis. As CD34 has been related with poor outcome in ALL in general, we investigated the prognostic significance of the stem cell marker CD34, as well as the association of CD34 positivity with the expression of several multidrug resistance (MDR) genes.

Procedure

In this retrospective study, we investigated the prognostic significance of the expression of the early T‐cell differentiation marker CD34 and the expression of MDR genes in relation to outcome in a cohort of 72 newly diagnosed pediatric T‐ALL patients.

Results

CD34 expression was related to a poor 5‐year disease‐free‐survival and a poor 5‐year overall survival. Using the Cox proportional hazard model, CD34 expression predicted for increased risk for relapse and death. Expression of CD34 was associated with elevated MDR1 and MRP1 mRNA expression levels. For the entire T‐ALL cohort, these expression levels of MDR1 or MRP1 did not independently predict for poor outcome.

Conclusions

We conclude that CD34‐positive T‐ALL has a relatively poor survival that is not explained by the mRNA expression levels of MDR1, LRP, or MRP1. Pediatr Blood Cancer 2008;51:737–740. © 2008 Wiley‐Liss, Inc.
Measuring the solubility of benzoic acid in room temperature ionic liquids using chronoamperometric techniques
Authors: He Weisi , Silvester Debbie S. , Streeter Ian , Aldous Leigh , Hardacre Christopher , Compton Richard G.
Published: August 2008

The electrochemical reduction of benzoic acid (BZA) has been studied at platinum micro‐electrodes (10 and 2 µm diameters) in acetonitrile (MeCN) and six room temperature ionic liquids (RTILs): [C2mim][NTf2], [C4mim][NTf2], [C4mpyrr][NTf2], [C4mim][BF4], [C4mim][NO3] and [C4mim][PF6] (where [Cnmim]+ = 1‐alkyl‐3‐methylimidazolium, [NTf2]− = bis(trifluoromethylsulphonyl)imide, [C4mpyrr]+ = N‐butyl‐N‐methylpyrrolidinium, [BF4]− = tetrafluoroborate, [NO3]− = nitrate and [PF6]− = hexafluorophosphate). Based on the theoretical fitting to experimental chronoamperometric transients in [C4mpyrr][NTf2] and MeCN at several concentrations and on different size electrodes, it is suggested that a fast chemical step preceeds the electron transfer step in a CE mechanism (given below) in both RTILs and MeCN, leading to the appearance of a simple one‐electron transfer mechanism.

The six RTIL solvents and MeCN were saturated with BZA, and potential‐step chronoamperometry revealed diffusion coefficients of 170, 4.6, 3.2, 2.7, 1.8, 0.26 and 0.96 × 10−11 m2 s−1 and solubilities of 850, 75, 78, 74, 220, 2850 and 48 mM in MeCN and the six ionic liquids, respectively, at 298 K. The high solubility of BZA in [C4mim][NO3] may suggest a strong interaction of the dissolved proton with the nitrate anion. Although there are relatively few literature reports of solubilities of organic solutes in RTILs at present, these results suggest the need for further studies on the solubilities of organic species (particularly acids) in RTILs, because of the contrasting interaction of dissolved species with the RTIL ions. Chronoamperometry is suggested as a convenient methodology for this purpose. Copyright © 2008 John Wiley & Sons, Ltd.
Preface: phys. stat. sol. (c) 5/10
Authors: Nickel Norbert H. , Mohammed‐Brahim Tayeb , Bonnaud Olivier
Published: August 2008

The following proceedings contain most of the invited and contributed papers presented at the international workshop on “Laser Processing for Semiconductor Devices – Science and Technology” that took place at the Palais du Grande Large in Saint Malo, France, on 1 and 2 October 2007. This workshop brought together more than 20 scientists from 8 countries in the inspiring atmosphere of the historic city of Saint Malo in the heart of the Emerald Coast.

The workshop covered many aspects of laser processing for materials ranging from silicon and its alloys to ferroelectric oxides, high‐k dielectrics films, zinc oxide, modeling of the processes, and device fabrication. These and other topics were discussed from a point of view of basic physics as well as current and future applications such as thin‐film solar cells, flexible displays, field emission displays, microwave devices, and sensors.

The organizers of the workshop would like to take the opportunity to thank all speakers and participants for their interesting contributions and state‐of‐the‐art research. Combined with vivid discussions it helped making this workshop a successful interdisciplinary event. We also would like to acknowledge the sponsors whose financial support took a considerable share in the successful course of the workshop. Finally, we would like to extend our special thanks to Miss Fabienne Jegousse who provided us with indispensable yet very efficient secretarial support.

Berlin and Rennes, May 2008
Investigation of the morphology, viability and mechanical properties of yeast cells in environmental SEM
Authors: Ren Yilong , Donald Athene M. , Zhang Zhibing
Published: August 2008

The mechanical properties of biological cells at nanoscale may be characterized using an environmental scanning electron microscopy (ESEM) combined with a force measurement device. However, the electron beam radiation in an ESEM may damage a specimen. So far, little is known about the radiation damage to biological cells. In this work, single yeast cells were imaged using an ESEM under both high and low vacuum modes. The changes in their morphology and viability were monitored as a function of radiation time for a given beam current of 538 pA corresponding to 10 kV accelerating voltage and spot size 4. Under the two modes, the radiation damage to the morphology of yeast cells became evident after an exposure time of 3 min, but under the low vacuum mode, the damage to their morphology was more severe. However, all cells lost their viability after 5 min under the high vacuum mode with the electron beam off from an initial viability of 95±1%. In contrast, the viability of cells under the low vacuum mode was found to be approximately 20% after 20 min. In addition, a newly developed ESEM‐based nanomanipulation technique was applied to measure the force imposed on single yeast cells and their deformation, including contact diameter and central lateral diameter for the compression of single yeast cells to a given displacement within a time frame of 1 min, and the data obtained may be used to validate mathematical modeling of the stress–strain relationship for the compression of cells in order to determine their intrinsic mechanical property parameters. SCANNING 30: 435–442, 2008. © 2008 Wiley Periodicals, Inc.
Humic acid induces G1 phase arrest and apoptosis in cultured vascular smooth muscle cells
Authors: Hseu You‐Cheng , Lin Elong , Chen Jing‐Yi , Liua Yi‐Ru , Huang Chun‐Yin , Lu Fung‐Jou , Liao Jiunn‐Wang , Chen Ssu‐Ching , Yang Hsin‐Ling
Published: August 2008

Humic acid (HA) in well water used by the inhabitants for drinking is one of the possible etiological factors for Blackfoot disease (BFD). In this study, the ability of HA to inhibit cell cycle progression and induce apoptosis in cultured smooth muscle cells (SMCs; A7r5) was investigated. Treatment of the SMCs at various HA concentrations (25–200 μg/mL) resulted in sequences of events marked by apoptosis, as shown by loss of cell viability, morphology change, and internucleosomal DNA fragmentation. HA‐induced apoptotic cell death that is associated with loss of mitochondrial membrane potential (ΔΨm), cytochrome c translocation, caspase‐3, ‐8, and ‐9 activation, poly ADP‐ribose polymerase (PARP) degradation, dysregulation of Bcl‐2 and Bax, and upregulation of p53 and phospholyrated p53 (p‐p53) in SMCs. Flow cytometry analysis demonstrated that HA blocked cell cycle progress in the G1 phase in SMCs. This blockade of cell cycle was associated with reduced amounts of cyclin D1, CDK4, cyclin E, CDK2, and hyperphosphorylated retinoblastoma protein (pRb) in a time‐dependent manner. Apparent DNA strand breaks (DNA damage) were also detected in a dose‐dependent manner using Single‐cell gel electrophoresis assay (comet assay). Furthermore, HA induced dose‐dependent elevation of reactive oxygen species (ROS) level in SMCs, and antioxidant vitamin C and Trolox effectively suppressed HA‐induced DNA damage and dysregulation of Bcl‐2/Bax. Our findings suggest that HA‐induced DNA damage, cell cycle arrest, and apoptosis in SMCs may be an underlying mechanisms for the atherosclerosis and thrombosis observed in the BFD endemic region. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009.
Determining nitrogen requirements of Aceros and Buceros hornbills
Authors: Foeken Sijmen G. , de Vries Max , Hudson Elisabeth , Sheppard Christine D. , Dierenfeld Ellen S.
Published: August 2008

Over 2 months, seven feeding trials were conducted at St. Catherines Island, GA, to quantify protein intake and utilization in captive mature nonreproducing Aceros (n=3 spp.) and Buceros (n=2 spp.) Hornbills were fed homogeneous isocaloric diets. A mixture of Bird of Paradise pellets, grapes, and raisins was offered to the birds as grape‐sized balls, supplemented with diced cantaloupe melon to maintain hydration. To vary the protein level (range 10.8–22.6%) within the diets, different amounts of a powdered soy protein supplement were added to the mixture. Test diets were fed for 3 consecutive days. Birds were weighed to test for differences among diets. All excreta and diet samples were collected for nitrogen (N) analysis. Feeding trials were separated by a 4‐day period, in which the bird's regular diet was fed. Data were analyzed for N balance, N equilibrium (regression of N intake vs. N excretion) and body mass. Regression analysis of N balances of the nine birds showed that the N equilibriums ranged from 0.081 to 0.595 g N/kg0.75/d with an average of 0.387±0.298. No differences in N balances were found between Aceros and Buceros hornbills. The methodology of this study suggested a dietary crude protein (CP) requirement of 7.3±3.0% dry matter (DM) in a diet containing 4.0 kcal. However, this value was determined by extrapolation and has not been experimentally determined to be adequate. In this study, the hornbills maintained body mass on a diet containing 10.8% CP (with energy at 4.0 kcal/g DM). Zoo Biol 27:282–293, 2008. © 2008 Wiley‐Liss, Inc.
Stearidonic Acid‐Enriched Soybean Oil Increased the Omega‐3 Index, an Emerging Cardiovascular Risk Marker
Authors: Harris William S. , Lemke Shawna L. , Hansen Susan N. , Goldstein Daniel A. , DiRienzo Maureen A. , Su Hong , Nemeth Margaret A. , Taylor Mary L. , Ahmed Gulam , George Cherian
Published: August 2008

A plant source of omega‐3 fatty acid (FA) that can raise tissue eicosapentaenoic acid (EPA) and/or docosahexaenoic acid (DHA) is needed. A soybean oil (SBO) containing approximately 20% stearidonic acid [SDA; the delta‐6 desaturase product of alpha‐linolenic acid (ALA)] derived from genetically modified soybeans is under development. This study compared the effects of EPA to SDA‐SBO on erythrocyte EPA + DHA levels (the omega‐3 index). Overweight healthy volunteers (n = 45) were randomized to SDA‐SBO (24 ml/day providing ~3.7 g SDA) or to regular SBO (control group) without or with EPA ethyl esters (~1 g/day) for 16 weeks. Serum lipids, blood pressure, heart rate, platelet function and safety laboratory tests were measured along with the omega‐3 index. A per‐protocol analysis was conducted on 33 subjects (11 per group). Compared to baseline, average omega‐3 index levels increased 19.5% in the SDA group and 25.4% in the EPA group (p < 0.05 for both, vs. control). DHA did not change in any group. Relative to EPA, SDA increased RBC EPA with about 17% efficiency. No other clinical endpoints were affected by SDA or EPA treatment (vs. control). In conclusion, SDA‐enriched SBO significantly raised the omega‐3 index. Since EPA supplementation has been shown to raise the omega‐3 index and to lower risk for cardiac events, SDA‐SBO may be a viable plant‐based alternative for providing meaningful intakes of cardioprotective omega‐3 FAs.
Waltzing in Arcadia: a Theatrical Dance in Five Dimensions
Authors: Limon Jerzy
Published: August 2008

Time structures are essential to any analysis of drama or theatre performance, and in this article Jerzy Limon takes the final scene from Tom Stoppard's Arcadia as an example to show that non-semantic systems such as music gain significance in the process of stage semiosis and may denote both space and time. The scene discussed is particularly complex owing to the fact that Stoppard introduces two different time-streams simultaneously in one space. The two couples presented dance to two distinct melodies which are played at two different times, and the author explains how the playwright avoided the confusion and chaos which would have inevitably resulted if the two melodies were played on the stage simultaneously. Jerzy Limon is Professor of English at the English Institute at the University of Gdańsk. His main area of research includes the history of English drama and theatre in the sixteenth and seventeenth centuries, and various theoretical aspects of theatre. His most recent works, published in 2008, include a book on the theory of television theatre, Obroty przestrzeni (Moving Spaces), two chapters in books, and articles in such journals as Theatre Research International, Shakespeare Jahrbuch, Journal of Drama Theory and Criticism, and Cahiers élisabéthains.
Representations of Greek Tragedy in Ancient Pottery: a Theatrical Perspective
Authors: Billing Christian M.
Published: August 2008

In this article, Christian M. Billing considers the relationship between representations of mythic narratives found on ancient pottery (primarily found at sites relating to the Greek colonies of south Italy in the fourth century BC, but also to certain vases found in Attica) and the tragic theatre of the fifth century BC. The author argues against the current resurgence in critical accounts that seek to connect such ceramics directly to performance of tragedies by the major tragedians: Aeschylus, Sophocles, and Euripides. Using five significant examples of what he considers to be errors of method in recent philologically inspired accounts of ancient pottery, Billing argues for a more nuanced approach to the interpretation of such artefacts – one that moves beyond an understanding of literary texts and art history towards a more performance-conscious approach, while also acknowledging that a multiplicity of spheres of artistic influence, drawn from a variety of artistic media, operated in the production and reception of such artefacts. Christian M. Billing is an academic and theatre practitioner working in the fields of ancient Athenian and early modern English and European drama. He has extensive experience as a director, designer, and actor, and has taught at a number of universities in the UK and the USA. He is currently Lecturer in Drama at the University of Hull.
Mechanisms that influence the formation of high‐ozone regions in the boundary layer downwind of the Asian continent in winter and spring
Authors: Kondo Y. , Hudman R. C. , Nakamura K. , Koike M. , Chen G. , Miyazaki Y. , Takegawa N. , Blake D. R. , Simpson I. J. , Ko M. , Kita K. , Shirai T. , Kawakami S.
Published: August 2008

The seasonal variation of ozone (O3) in the boundary layer (BL) over the western Pacific is investigated using a chemistry‐transport model. The model results for January and April–May 2002 were evaluated by comparison with PEACE aircraft observations. In January, strong northwesterlies efficiently transported NOx from the continent, leading to an O3 increase of approximately 5–10 ppbv over a distance of about 3000 km. In April, southwesterlies dominated due to anticyclone development over the western Pacific. Along this flow, O3 continued to be produced by NOx emitted from East Asia. This resulted in the formation of a high‐O3 (> 50 ppbv) region extending along the coastal areas of East Asia. This seasonal change in O3 was driven in part by a change in the net O3 production rate due to increases in solar UV and H2O. Its exact response depended on the NOx values in the BL. The net O3 production rate increased between winter and spring over the Asian continent and decreased over the remote western Pacific. Model simulations show that about 25% of the total O3 (of 10–20 ppbv) increase over the coastal region of Northeast Asia was due to local production from NOx emissions from China, and the rest was due to changes in background levels as well as emissions from Korea, Japan, and east Siberia. Uplift of BL air over Asia, horizontal transport in the free troposphere, and subsidence were the principal mechanisms of transporting Asian O3 to the central and eastern North Pacific.
Assessing the ability of the 14C projection‐age method to constrain the circulation of the past in a 3‐D ocean model
Authors: Franke J. , Schulz M. , Paul A. , Adkins J. F.
Published: August 2008

Radiocarbon differences between benthic and planktonic foraminifera (B‐P ages) and radiocarbon projection ages are both used to determine changes of the past ocean circulation rate. A global 3‐D ocean circulation model with a constant modern ocean circulation is used to study which method is less influenced by atmospheric Δ14C variations. Three factors cause uncertainties: first, the long equilibration time of the ocean after atmospheric Δ14C changes; second, different mixing processes in the ocean, which cause an ocean response of smaller amplitude than the atmospheric forcing; and third, the unknown source region and corresponding initial surface 14C reservoir age of subsurface waters. The model suggests that B‐P ages and projection ages have lower uncertainties the closer they are to deepwater formation zones. In the North Atlantic the B‐P age method is less influenced by atmospheric Δ14C variations than the projection‐age method. Projections ages vary less in the Pacific as long as atmospheric Δ14C decreases linearly. A more irregular atmospheric Δ14C evolution leads to age variations of similar magnitude with both methods. On the basis of the model experiment, we suggest a potential improvement of the projection‐age method.
Derivation of global hyperspectral resolution surface emissivity spectra from advanced infrared sounder radiance measurements
Authors: Li Jun , Li Jinlong
Published: August 2008

The global IR surface emissivity spectra are very important for retrieving products such as dust properties, land surface temperature, trace gases, and cloud‐top properties, as well as assimilating hyperspectral resolution IR radiances in NWP models over land. In this study, global IR surface emissivity spectra have been generated by using AIRS radiance measurements from NASA's EOS Aqua platform. A one‐dimensional variation retrieval algorithm was used for retrieving the global hyperspectral resolution IR surface emissivity product. The 8‐day composite of AIRS IR surface emissivity retrievals agrees well with the operational MODIS emissivity product (collection 4.0) at a few broad spectral bands, with the differences less than 0.02 in most regions for 8.55 μm spectral band; in addition, the AIRS retrievals provide more complete spectral information. The spatial and spectral features of the derived emissivity over desert and other regions reflect the ecosystem surface types, but show more variability than IGBP classification.
Importance of the quality of metal and ligand basis sets in transition metal species
Authors: Gavin Williams T. , Wilson Angela K.
Published: August 2008

Recent development of pseudopotential-based correlation consistent basis sets (cc-pVnZ-PP) by Peterson and Puzzarini [Theor. Chem. Acc. 114, 283 (2005)] has enabled the relative importance of metal versus ligand basis set size to be examined systematically. The impact of basis set choice on geometries and dissociation energies for a series of group 11 transition metal species has been assessed via three series of calculations: (1) systematically increasing the size of the cc-pVnZ-PP basis set on the metal while holding the basis set on the ligand constant, (2) systematically increasing the size of the cc-pVnZ basis set on the ligand while holding the basis set on the metal constant, and (3) systematically increasing the size of the basis set on both the metal and the ligand. Holding the ligand basis set static while systematically increasing the metal basis set results in changes in the equilibrium bond length that are an order of magnitude smaller than for calculations where the metal basis set is held constant and the quality of the ligand basis set is systematically increased. Interestingly, holding the metal basis set static while systematically increasing the basis set size on the ligand results in monotonic convergence of dissociation energies with respect to increasing basis set size, while maintaining the basis set size on the ligand and increasing the size of the basis set on the metal do not result in monotonic convergence. Also, variance of the ligand basis set size has a greater impact on the energetics than variance of the metal basis set size. This suggests that the choice of basis set for the ligands is much more important for accurate chemical description than the choice of the transition metal basis set for these species and properties. In fact, complete basis set limit dissociation energies obtained from increasing the size of the basis set on the ligand while maintaining a constant level basis set on the metal at any level basis set result in similar energies to those obtained utilizing large basis sets on both the metal and the ligand at significant computational cost savings.
The rotational spectrum and structure for the argon-cyclopentadienyl thallium van der Waals complex: Experimental and computational studies of noncovalent bonding in an organometallic π-complex
Authors: Tanjaroon Chakree , Daly Adam M. , Kukolich Stephen G.
Published: August 2008

The rotational spectrum of a noble gas–organometallic complex was measured using a pulse molecular beam Fourier transform microwave spectrometer. Rotational transitions for the neutral argon-cyclopentadienyl thallium weakly bound complex were measured in the 4–9 GHz range. Analysis of the spectrum showed that the complex is a prolate symmetric-top rotor with C5V symmetry. The experimentally determined molecular parameters for Ar–C5H5T205l are B=372.4479(3) MHz, DJ=0.123(2) kHz, and DJK=0.45(2) kHz. For Ar–C5H5T203l, B=373.3478(5) MHz, DJ=0.113(3) kHz, and DJK=0.37(3) kHz. Using a pseudodiatomic model with Lennard-Jones potential yields an approximate binding energy of 339 cm−1. The argon atom is located on the a-axis of the C5H5Tl monomer, directly opposite from the thallium metal atom. The measured separation distance between argon and the cyclopentadienyl ring is R=3.56 Å. The overall size of the cluster is about 6 Å, measuring from argon to thallium. Relatively small DJ and DJK centrifugal distortion constants were observed for the complex, indicating that the structure of Ar–C5H5Tl is somewhat rigid. MP2 calculations were used to investigate the possible structures and binding energies of the argon-cyclopentadienyl thallium complex. Calculated, counterpoise corrected binding energies are evaluated at R=3.56 Å for Ar–C5H5Tl range from 334 to 418 cm−1. The experimental binding energy ε=339 cm−1 for Ar–C5H5Tl falls within this range. The higher-level MP2/aug-cc-pVTZ-PP (thallium)/aug-cc-pVTZ(Ar, C, H) calculation with variable R yielded Re=3.46 Å and binding energy of 535 cm−1. Our estimated binding energy for argon-cyclopentadienyl thallium is very similar to the binding energy of argon-benzene. Calculations for the new van der Waals complexes, Ar(C5H5Tl)2 and (C5H5Tl)2, have been obtained, providing further information on the structures and bonding properties of previously observed cyclopentadienyl thallium polymer chains. The calculated intermolecular distance RTl-Cp=3.05 Å for the (CpTl)2 chain subunit (Cp is cyclopentadienyl, C5H5) is slightly longer than the measured x-ray value RM–Cp(M=Tl)=2.75 Å. The x-ray distance RTl–Tl=5.5 Å for the chain structure is almost identical to the calculated RTl–Tl=5.51 Å for the (C5H5Tl)2 dimer.
The electronic structure and energetics of V+-benzene half-sandwiches of different multiplicities: Comparative multireference and single-reference theoretical study
Authors: Polestshuk Pavel M. , Dem’yanov Piotr I. , Ryabinkin Ilya G.
Published: August 2008

Multireference [complete active space self-consistent field (CASSCF) and multiconfigurational quasidegenerate perturbation theory (MCQDPT)] and single-reference ab initio (Møller–Plesset second order perturbation theory (MP2) and coupled clusters with singles, doubles and noniterative triples [CCSD(T)]) and density functional theory (PBE and B3LYP) electronic structure calculations of V(C6H6)+ half-sandwich in the states of different multiplicities are described and compared. Detailed analyses of the geometries and electronic structures of the all found states are given; adiabatic and diabatic dissociation energies are estimated. The lowest electronic state of V(C6H6)+ half-sandwich was found to be the quintet B52 state with a slightly deformed upside-down-boat-shaped benzene ring and d4 configuration of V atom, followed by a triplet A32 state lying about 4 kcal/mol above. The lowest singlet state A11(d4) lies much (∼28 kcal/mol) higher. MCQDPT calculated adiabatic dissociation energy (53.6 kcal/mol) for the lowest B52(d4) state agrees well with the current 56.4 (54.4) kcal/mol experimental estimate, giving a preference to the lower one. Compared to MCQDPT, B3LYP hybrid exchange-correlation functional provides the best results, while CCSD(T) performs usually worse. Gradient-corrected PBE calculations tend to systematically overestimate metal-benzene binding in the row quintet<triplet<singlet.
Theoretical study on the electronic states of NaLi
Authors: Petsalakis Ioannis D. , Tzeli Demeter , Theodorakopoulos Giannoula
Published: August 2008

Configuration interaction calculations have been carried out on electronic states of the NaLi molecule and the cation NaLi+. Potential energy curves are presented for the lowest nine Σ1+, seven Π1, four Δ1, eight Σ3+, seven Π3, and four Δ3 states of NaLi as well as for the lowest ten Σ2+, six Π2, and two Δ2 states of NaLi+. The results of the present many-electron configuration interaction calculations on the cation are in support of previous core-polarization effective potential calculations. The present calculations on the NaLi molecule are complementary to previous theoretical work on this system, including recently observed electronic states that had not been calculated previously as well as an investigation of nonadiabatic effects leading to spectral perturbations. Furthermore, ab initio potential energy curves of the neutral and the ground state of the cation are employed to determine quantum defect that may be employed to generate potential energy curves for nd and (n+1)p (for n>3) Rydberg states of NaLi. The present results on the 3 1Π and 4 1Π states are in good agreement with recent experimental work, whereas on the basis of theoretical data, the recently observed state 5 1Π is better described as 6 1Π.
Magnetic properties of Fe–Co catalysts used for carbon nanofiber synthesis
Authors: Sorge K. D. , Klein K. L. , Melechko A. V. , Finkel C. L. , Malkina O. , Leventouri Th. , Fowlkes J. D. , Rack P. D. , Simpson M. L.
Published: August 2008

The magnetic properties of Fe–Co alloys used as catalysts for vertically aligned carbon nanofiber growth are presented at several stages in the formation process: from thin films to dewetted islands to carbon-encapsulated particles. Electron microscopy shows their morphological properties as a function of the alloy ratio. The magnetic properties are investigated by superconducting quantum interference device magnetometry in a field range of |H|≤20 kOe and temperatures between 2 and 330 K. Magnetization measurements illustrate a composition dependence of the magnetic properties. In addition, there is a significant amount of metal that is not incorporated in the resultant catalyst particles. This metal is superparamagnetic (SPM) and features of the magnetization curve shed light on the magnetic moment distribution of these SPM clusters.
Cooperativity of hydrogen-bonded networks in 7-azaindole(CH3OH)n (n=2,3) clusters evidenced by IR-UV ion-dip spectroscopy and natural bond orbital analysis
Authors: Sakota Kenji , Kageura Yutaka , Sekiya Hiroshi
Published: August 2008

IR-UV ion-dip spectra of the 7-azaindole (7AI)(CH3OH)n (n=1–3) clusters have been measured in the hydrogen-bonded NH and OH stretching regions to investigate the stable structures of 7AI(CH3OH)n (n=1–3) in the S0 state and the cooperativity of the H-bonding interactions in the H-bonded networks. The comparison of the IR-UV ion-dip spectra with IR spectra obtained by quantum chemistry calculations shows that 7AI(CH3OH)n (n=1–3) have cyclic H-bonded structures, where the NH group and the heteroaromatic N atom of 7AI act as the proton donor and proton acceptor, respectively. The H-bonded OH stretch fundamental of 7AI(CH3OH)2 is remarkably redshifted from the corresponding fundamental of (CH3OH)2 by 286cm−1, which is an experimental manifestation of the cooperativity in H-bonding interaction. Similarly, two localized OH fundamentals of 7AI(CH3OH)3 also exhibit large redshifts. The cooperativity of 7AI(CH3OH)n (n=2,3) is successfully explained by the donor-acceptor electron delocalization interactions between the lone-pair orbital in the proton acceptor and the antibonding orbital in the proton donor in natural bond orbital (NBO) analyses.
On the nodal structure of single-particle approximation based atomic wave functions
Authors: Bressanini Dario , Morosi Gabriele
Published: August 2008

The nodal structures of atomic wave functions based on a product of spatial orbitals, namely, restricted, unrestricted, and generalized valence bond wave functions, are shown to be equivalent. This result is verified by fixed node–diffusion Monte Carlo simulations for atoms up to Ne. Also for a molecular system, Li2 at the equilibrium geometry, a multideterminantal generalized valence bond wave function does not improve the nodal surfaces of a restricted Hartree–Fock wave function.
Design and characterization of a thermal hydrogen atom source
Authors: Tschersich K. G. , Fleischhauer J. P. , Schuler H.
Published: August 2008

The hydrogen atom source considered here incorporates a hot capillary fed by hydrogen gas. Our earlier measurements on a source heated by electron bombardment are interpreted in terms of a simple model which encourages us to design a source heated by the radiation from a filament. The radiatively heated source is much simpler, more reliable, and easier to run than the electronically heated source. Furthermore, the radiatively heated source is free of any energetic particles. In order to obtain quantitative data on the intensity, an apparatus is constructed revealing the angular distribution of the hydrogen atoms and molecules by means of a quadrupole mass analyzer. The intensity of the source is controlled by the mass flow rate of the feed gas and the electric power to the filament. The flux density of hydrogen atoms at a substrate 6 cm away from the source is variable over two orders of magnitude and extends up to some 1015 atoms/cm2 s.
Effect of Ti substitution on multiferroic properties of BiMn2O5
Authors: Shukla D. K. , Mollah S. , Kumar Ravi , Thakur P. , Chae K. H. , Choi W. K. , Banerjee A.
Published: August 2008

We present here the magnetic, dielectric, and electronic structural properties of Ti doped BiMn2O5 multiferroic materials. The x-ray diffraction (XRD) studies of BiMn2−xTixO5 (0≤x≤0.5) indicate no structural change up to x=0.5, though the lattice parameters (a and c) increase with increasing value of x. Dielectric constant and magnetization data show the evolution of new dielectric anomalies at ∼120 K and weak magnetic feature at ∼86 K with the Ti substitution compared to that of undoped one. However, Ti replacement vanishes the ferroelectric transition of BiMn2O5 at ∼35 K and gradually suppresses the antiferromagnetic ordering at ∼39 K. Polarization of Bi 6s2 lone pair electrons is attributed to the reason behind new dielectric anomalies, whereas new weak magnetic feature at ∼86 K is attributed to strong spin-phonon coupling. X-ray absorption spectroscopy (XAS) studies on O K, Mn K, L3,2, and Ti L3,2 edges of BiMn2−xTixO5 samples along with the reference compounds have been performed and compared to bestow the exact chemical states of functioning ions. The Ti L-edge spectra clearly indicate the substitution of Ti4+ ions in all samples. XRD as well as XAS data and increase in net magnetic moment coherently indicate the replacement of Mn4+ by Ti4+.
Improvement of a dynamic scanning force microscope for highest resolution imaging in ultrahigh vacuum
Authors: Torbrügge S. , Lübbe J. , Tröger L. , Cranney M. , Eguchi T. , Hasegawa Y. , Reichling M.
Published: August 2008

We report on a modification of a commercial scanning force microscope (Omicron UHV AFM/STM) operated in noncontact mode (NC-AFM) at room temperature in ultrahigh vacuum yielding a decrease in the spectral noise density from 2757 to 272 fm/Hz. The major part of the noise reduction is achieved by an exchange of the originally installed light emitting diode by a laser diode placed outside the vacuum, where the light is coupled into the ultrahigh vacuum chamber via an optical fiber. The setup is further improved by the use of preamplifiers having a bandpass characteristics tailored to the cantilever resonance frequency. The enhanced signal to noise ratio is demonstrated by a comparison of atomic resolution images on CeO2(111) obtained before and after the modification.
Local structure of indium oxynitride from x-ray absorption spectroscopy
Authors: T-Thienprasert J. , Nukeaw J. , Sungthong A. , Porntheeraphat S. , Singkarat S. , Onkaw D. , Rujirawat S. , Limpijumnong S.
Published: August 2008

Synchrotron x-ray absorption near edge structures (XANES) measurements of In L3 edge is used in conjunction with first principles calculations to characterize rf magnetron sputtered indium oxynitride at different O contents. Good agreement between the measured and the independently calculated spectra are obtained. Calculations show that the XANES spectra of this alloy are sensitive to the coordination numbers of the In atoms, i.e., fourfold for indium nitride-like structures and sixfold for indium oxide-like structures, but not to the substitution of nearest neighbor N by O or vice versa.
CdSe quantum dot-decorated double walled carbon nanotubes: The effect of chemical moieties
Authors: Kim Yoong Ahm , Muramatsu Hiroyuki , Park Ki Chul , Shimamoto Daisuke , Jung Yong Chae , Kim Jin Hee , Hayashi Takuya , Saito Yasunori , Endo Morinobu , Terrones Mauricio , Dresselhaus Mildred S.
Published: August 2008

We report that fluorine atoms on the outer tubes of double walled carbon nanotubes (DWNTs) are more effective for nucleating and growing CdSe nanoparticles than oxygen-containing functional groups. The CdSe particles with an average size of 5–7 nm grow through infiltration into an interstitial space created by four to five thin bundled DWNTs. We envisage that DWNTs will replace single and multiwalled carbon nanotubes in a wide range of applications because chemical moieties could be introduced selectively on the outer tubes while the optical and physical properties of the inner tubes remain almost unchanged.
Room temperature polariton lasing in a GaN∕AlGaN multiple quantum well microcavity
Authors: Christmann Gabriel , Butté Raphaël , Feltin Eric , Carlin Jean-François , Grandjean Nicolas
Published: August 2008

The authors report room temperature polariton lasing at λ∼345nm in a hybrid AlInN∕AlGaN multiple quantum well microcavity (MQW-MC) containing a GaN∕AlGaN MQW active region, i.e., the achievement under nonresonant optical excitation of coherent light emission of a macroscopic population of polaritons occupying the lowest energy state of the lower polariton branch. This was made possible by taking advantage of the efficient relaxation of polaritons in a MQW-MC exhibiting a large vacuum Rabi splitting ΩVRS=56meV.
Magnetic anisotropy in ferromagnetic Josephson junctions
Authors: Weides M.
Published: August 2008

Magnetotransport measurements were done on Nb∕Al2O3∕Cu∕Ni∕Nb superconductor-insulator-ferromagnet-superconductor Josephson tunnel junctions. Depending on ferromagnetic Ni interlayer thickness and geometry, the standard (1d) magnetic field dependence of critical current deviates from the textbook model for Josephson junctions. The results are qualitatively explained by a short Josephson junction model based on anisotropy and 2d remanent magnetization.
Carrier relaxation through two-electron process during photoconduction in highly UV sensitive quasi-one-dimensional ZnO nanowires
Authors: Bera A. , Basak D.
Published: August 2008

We have investigated the carrier relaxation process during photoconduction in quasi-one-dimensional (Q1D) ZnO nanowires (NWs) of diameters 29–36nm on different substrates using photocurrent transient measurements. Ultraviolet (UV) sensitive NWs show around three to four orders of change in the photo-to-dark current ratio. Under steady UV illumination, the photocarrier relaxation occurs through two-electron process—carrier loss due to the trapping by the surface states and recombination at the deep defect states. The results demonstrate that the carrier relaxation during photoconduction in Q1D NWs of diameter comparable to the Debye length is also dominated by the surface states.
Temperature-stable operation of a quantum dot semiconductor disk laser
Authors: Germann T. D. , Strittmatter A. , Pohl J. , Pohl U. W. , Bimberg D. , Rautiainen J. , Guina M. , Okhotnikov O. G.
Published: August 2008

We demonstrate temperature-independent output characteristics of an optically pumped semiconductor disk laser (SDL) based on quantum dots (QDs) grown in the Stranski-Krastanow regime. The gain structure consists of a stack of 7×3 QD layers, each threefold group being located at an optical antinode position. The SDL emits at 1210nm independent of the pump power density. Threshold and differential efficiency do not dependent on heat sink temperature. Continuous-wave operation close to 300mW output power is achieved using the ground-state transition of the InGaAs QDs.
Enhancement of surface plasmon-mediated radiative energy transfer through a corrugated metal cathode in organic light-emitting devices
Authors: Feng Jing , Okamoto Takayuki , Naraoka Ryo , Kawata Satoshi
Published: August 2008

We report enhanced top emission from organic light-emitting devices by surface plasmon-mediated radiative energy transfer. A dye-doped dielectric acceptor layer was deposited onto the surface of a one-dimensionally corrugated silver cathode and was excited by the electroluminescence of a donor layer, which is located at the other side of the cathode. Ten times enhancement in emission intensity from the acceptor was observed compared to flat devices; this is due to the enhanced radiative energy transfer from the donor to the acceptor by the coupled surface plasmons on the opposite interfaces of the silver cathode.
Plant-available nitrogen supply from granulated biosolids: implications for land application guidelines
Authors: Eldridge S. M. , Chan K. Y. , Xu Z. H. , Chen C. R. , Barchia I.
Published: August 2008

Current State government guidelines attempt to ensure that the supply of plant available nitrogen (PAN) from land-applied biosolids does not exceed the crop’s requirement for mineral nitrogen (N), in order to minimise the risk of excess nitrate contaminating surface and groundwater. In estimating a suitable application rate, current guideline methodology assumes a fixed proportion of the organic N in the biosolids will be mineralised in the first year following the application for all situations. Our study included a field trial and a field incubation study to assess N mineralisation for both a granulated biosolid and a dewatered biosolid product, together with an additional laboratory incubation study for the granulated biosolid product. The application rates were 12, 24, and 48 dry t/ha for the granulated biosolids and 22 dry t/ha for the dewatered biosolids.
Our results showed that the guideline procedure underestimated the supply of mineral N from the biosolid-treated soils, with more than 3 times the predicted amount being supplied by the biosolids at all application rates. The excess supply of mineral N was due to a much larger proportion of the biosolid organic N being mineralised than the assumed 25%, as well as a significant contribution of mineral N from the soil itself (which is ignored in the estimation calculation). The proportion of biosolid organic N mineralised in the 12-month field incubation study for the 3 granulated biosolid treatments (12, 24, and 48 dry t/ha) and the dewatered biosolid treatment (22 dry t/ha) were estimated to be 54%, 48%, 45%, and 53%, respectively, in our field incubation study. Both the laboratory and field incubation studies found that most of the biosolid mineralisable organic N was mineralised rapidly during the early stages of the incubation. In the field incubation, the 24 dry t/ha granulated biosolid treatment had 35% of its organic N mineralised within the first 2 months following application, while all granulated biosolid treatments in the laboratory incubations had by, day 29, supplied >50% of the mineral N they would supply for the whole 216-day incubation. This release pattern for the supply of PAN from biosolid organic N should be factored into fertiliser application strategies. Our study reveals some of the shortcomings of the currently recommended ‘one size fits all’ approach for estimating the PAN supply from land-applied biosolids. Further research on the development of an effective rapid assessment for the mineralisable N content in organic wastes and soils, in combination with modelling, may improve our capacity to predict PAN supply from land-applied organic wastes in the future.
Induction of angiogenesis in tissue-engineered scaffolds designed for bone repair: A combined gene therapy–cell transplantation approach
Authors: Jabbarzadeh Ehsan , Starnes Trevor , Khan Yusuf M. , Jiang Tao , Wirtel Anthony J. , Deng Meng , Lv Qing , Nair Lakshmi S. , Doty Steven B. , Laurencin Cato T.
Published: August 2008

One of the fundamental principles underlying tissue engineering approaches is that newly formed tissue must maintain sufficient vascularization to support its growth. Efforts to induce vascular growth into tissue-engineered scaffolds have recently been dedicated to developing novel strategies to deliver specific biological factors that direct the recruitment of endothelial cell (EC) progenitors and their differentiation. The challenge, however, lies in orchestration of the cells, appropriate biological factors, and optimal factor doses. This study reports an approach as a step forward to resolving this dilemma by combining an
ex vivo
gene transfer strategy and EC transplantation. The utility of this approach was evaluated by using 3D poly(lactide-co-glycolide) (PLAGA) sintered microsphere scaffolds for bone tissue engineering applications. Our goal was achieved by isolation and transfection of adipose-derived stromal cells (ADSCs) with adenovirus encoding the cDNA of VEGF. We demonstrated that the combination of VEGF releasing ADSCs and ECs results in marked vascular growth within PLAGA scaffolds. We thereby delineate the potential of ADSCs to promote vascular growth into biomaterials.
Conformational isomerization kinetics of pent-1-en-4-yne with 3,330 cm
−1
of internal energy measured by dynamic rotational spectroscopy
Authors: Dian Brian C. , Brown Gordon G. , Douglass Kevin O. , Rees Frances S. , Johns James E. , Nair Pradeep , Suenram Richard D. , Pate Brooks H.
Published: August 2008

We demonstrate the application of molecular rotational spectroscopy to measure the conformation isomerization rate of vibrationally excited pent-1-en-4-yne (pentenyne). The rotational spectra of single quantum states of pentenyne are acquired by using a combination of IR–Fourier transform microwave double-resonance spectroscopy and high-resolution, single-photon IR spectroscopy. The quantum states probed in these experiments have energy eigenvalues of ≈3,330 cm
−1
and lie above the barrier to conformational isomerization. At this energy, the presence of intramolecular vibrational energy redistribution (IVR) is indicated through the extensive local perturbations found in the high-resolution rotation–vibration spectrum of the acetylenic C–H stretch normal-mode fundamental. The fact that the IVR process produces isomerization is deduced through a qualitatively different appearance of the excited-state rotational spectra compared with the pure rotational spectra of pentenyne. The rotational spectra of the vibrationally excited molecular eigenstates display coalescence between the characteristic rotational frequencies of the stable
cis
and
skew
conformations of the molecule. This coalescence is observed for quantum states prepared from laser excitation originating in the ground vibrational state of either of the two stable conformers. Experimental isomerization rates are extracted by using a three-state Bloch model of the dynamic rotational spectra that includes the effects of chemical exchange between the stable conformations. The time scale for the conformational isomerization rate of pentenyne at total energy of 3,330 cm
−1
is ≈25 ps and is 50 times slower than the microcanonical isomerization rate predicted by the statistical Rice–Ramsperger–Kassel–Marcus theory.