bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Valence Bond Study of the Low‐Lying States of the NF Molecule
Authors: Su Peifeng , Wu Wei , Shaik Sason , Hiberty Philippe C. 
Published: May 2008

AbstractThe electronic structures of the three lowest‐lying states of NF are investigated by means of modern valence bond (VB) methods such as the VB self‐consistent field (VBSCF), breathing orbital VB (BOVB), and VB configuration interaction (VBCI) methods. The wave functions for the three states are expressed in terms of 9–12 VB structures, which can be further condensed into three or four classical Lewis structures, whose weights are quantitatively estimated. Despite the compactness of the wave functions, the BOVB and VBCI methods reproduce the spectroscopic properties and dipole moments of the three states well, in good agreement with previous computational studies and experimental values. By analogy to the isoelectronic O2 molecule, the ground state 3Σ− possesses both a σ bond and 3‐electron π bonds. However, here the polar σ bond contributes the most to the overall bonding. It is augmented by a fractional (19 %) contribution of three‐electron π bonding that arises from π charge transfer from fluorine to nitrogen. In the singlet 1Δ and 1Σ+ excited states the π‐bonding component is classically covalent, and it contributes 28 % and 37 % to the overall bonding picture for the two states, respectively. The resonance energies are calculated and reveal that π bonding contributes at least 24, 35 and 42 kcal mol−1 to the total bonding energies of the 3Σ−, 1Δ and 1Σ+ states, respectively. Some unusual properties of the NF molecule, like the equilibrium distance shortening and bonding energy increasing upon excitation, the counterintuitive values of the dipole moments and the reversal of the dipole moments as the bond is stretched, are interpreted in the light of the simple valence bond picture. The overall polarity of the molecule is very small in the ground state, and is opposite to the relative electronegativity of N vs F in the singlet excited states. The values of the dipole moments in the three states are quantitatively accounted for by the calculated weights of the VB structures.
Photoinduced Luminescence Blinking and Bleaching in Individual Single‐Walled Carbon Nanotubes
Authors: Georgi Carsten , Hartmann Nicolai , Gokus Tobias , Green Alexander A. , Hersam Mark C. , Hartschuh Achim 
Published: May 2008

AbstractThe temporal evolution of photoluminescence in individual single‐walled carbon nanotubes (SWNT) under strong laser irradiation is studied and pronounced blinking and bleaching is observed, caused by photoinduced oxidation that subsequently quenches mobile excitons. The nanotubes are isolated with sodium cholate and spun onto either a glass or mica surface. Their bleaching behavior is investigated for variable laser intensities in air and argon atmosphere. The decay rate for luminescence bleaching generally increases with higher laser intensity, however saturating on mica substrates, which is attributed to limited availability of oxygen in the vicinity of the nanotubes. Step‐like events in the luminescence time traces corresponding to single oxidation events are analyzed regarding relative step height and suggest an exciton diffusion range of about 105 nm.
Localized and load‐balanced clustering for energy saving in wireless sensor networks
Authors: Huang Yueh‐Min , Su Bey‐Ling , Wang Ming‐Shi 
Published: May 2008

AbstractIn this paper, the ‘localized and load‐balanced clustering (LLBC)’ protocol is proposed for the energy savings and lifetime increases of wireless sensor networks. LLBC contains two approaches. One is improved cluster head rotation (ICHR) and the other is modified static clustering (MSC). ICHR uses the present cluster heads to select most energetic sensors as the next‐round cluster heads and avoids the margin cluster heads being selected as cluster heads repeatedly. MSC is suitable when the network has a few very high energetic sensors. It uses the method of inter‐cluster load balance to adjust the cardinality of each cluster as close to the average cardinality as possible. The simulation results with respect to FND (the time when a node dies first), HND (the time when half of the total nodes have died), and energy consumption show that the orders of effectiveness are: for ICHR and low‐energy adaptive clustering hierarchy (LEACH)‐C, before 250 rounds of cluster head rotations, there is no significant difference between the two, but after 250 rounds, ICHR>LEACH−C; and in general, LEACH−C>LEACH>MSC>mini variance>direct communication. Copyright © 2008 John Wiley & Sons, Ltd.
Diabetic retinopathy: a review
Authors: Chu June , Ali Yusuf 
Published: May 2008

AbstractDiabetic retinopathy is a progressive disease elicited by chronic exposure to high blood glucose, e.g., hyperglycemia and is generally recognized as a vascular disease like other diabetes‐related diseases. Although the pathogenesis of diabetic retinopathy has not been clearly elucidated, numerous drugs have been developed based on the current understanding of the complicated and intricate biochemical and pathophysiological aspects of the disease. Current therapy for diabetic retinopathy includes laser photocoagulation, surgery, and metabolic control. Future therapies for diabetic retinopathy are based on the pathophysiology of the disease, such as anti‐VEGF, anti‐angiogenesis, and anti‐inflammatory and anti‐extracellular matrix pathways. Several clinical trials are ongoing for diabetic macular edema using drug delivery routes including intravitreal injections, subtenon injections and intravenous injection, topical drops, and intravitreal implants. Drug Dev Res 69:1–14, 2008. © 2008 Wiley‐Liss, Inc.
Effects of labedipinedilol‐A, third‐generation dihydropyridine‐type calcium blocker, on ouabain‐induced arrhythmia
Authors: Liang Jhy‐Chong , Huang An‐Hsiang , Wu Jiunn‐Ren , Liou Shu‐Fen , Dai Zen‐Kong , Chen Ing‐Jun , Yeh Jwu‐Lai 
Published: May 2008

AbstractLabedipinedilol‐A, a novel dihydropyridine‐type calcium antagonist with α/β‐adrenoceptor blocking properties, has been reported to produce a cardioprotective effect against ischemia reperfusion injury in rats. We investigated the protective effects of labedipinedilol‐A on ouabain‐induced tonotropy and arrhythmias in isolated whole atria, and using patch‐clamp techniques to study the underlying mechanism of its antiarrhythmic activity on isolated cardiac myocytes. Labedipinedilol‐A (10 µM) suppressed the tonotropic effect of ouabain significantly and prolonged the onset time of extra‐systole (arrhythmia) induced by ouabain in isolate atria. In the voltage‐clamp study, labedipinedilol‐A (1–100 µM) reduced the peak amplitude of sodium inward current (INa) and L‐type calcium current (ICa‐L), and shifted the current‐voltage (I‐V) curve upward in a concentration‐dependent manner. In contrast, the addition of labedipinedilol‐A increased transient outward potassium current (Ito) and inward rectifier potassium current (IK1) significantly. Labedipinedilol‐A (10 µM) also effectively depressed the isoproterenol‐induced increase in the Ca2+ current. These results show that labedipinedilol‐A blocks ICa‐L and INa, and increases Ito and IK1. These findings indicate that labedipinedilol‐A produces direct cardiac action, probably due to the inhibition of cardiac Na+ and Ca2+ channels. Our results suggest that labedipinedilol‐A may reduce the membrane conduction through inhibition of ionic channels which decrease ouabain‐induced arrhythmia. Drug Dev Res 69:26–33, 2008 © 2008 Wiley‐Liss, Inc.
Improvement of physicochemical and biopharmaceutical properties of flurbiprofen using melt sonocrystallization technique
Authors: El‐Kamel Amal H. 
Published: May 2008

AbstractThe aim of the present study was to investigate the suitability of the melt sonocrystallization technique to modify the undesirable properties of the nonsteroidal anti‐inflammatory drug (NSAID), flurbiprofen (FBP), e.g., poor flowability, solubility, and dissolution rate and, consequently, poor bioavailability. FBP melt was poured in deionized water at 25°C and sonicated for 4 min at an amplitude of 60% and cycle of 40 s on and 10 s off. The product obtained was evaluated using scanning electron microscopy (SEM), image analysis, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT‐IR), and X‐ray powder diffraction (XRPD). Flow properties, intrinsic dissolution rate, solubility, and bioavailability were also evaluated. The particle size of the treated FBP was significantly reduced. Thermal behavior and FT‐IR spectra of untreated and treated FBP have shown no significant difference. Low‐intensity peaks in the X‐ray diffraction of treated FBP were noticed. In addition there was significant enhancement in the flow properties of treated FBP, as indicated by the value of angle of repose and the flow constants calculated from the Kawakita equation. The increased solubility of treated FBP was about 35%. The intrinsic dissolution rate of treated FBP increased by 2‐fold. The dissolution rate studies revealed that 90% of the drug was released within 20 min for treated FBP compared with 60% released for the untreated drug. The relative bioavailability of treated FBP was increased by 2‐fold compared with untreated drug.The use of melt sonocrystallization technique is a promising technique that may afford powder with improved flow and tablet functionality as well as improved dissolution and bioavailability. Drug Dev Res 69:34–41, 2008 © 2008 Wiley‐Liss, Inc.
Neural agrin increases postsynaptic ACh receptor packing by elevating rapsyn protein at the mouse neuromuscular synapse
Authors: Brockhausen Jennifer , Cole Rebecca N. , Gervásio Othon L. , Ngo Shyuan T. , Noakes Peter G. , Phillips William D. 
Published: May 2008

AbstractFluorescence resonance energy transfer (FRET) experiments at neuromuscular junctions in the mouse tibialis anterior muscle show that postsynaptic acetylcholine receptors (AChRs) become more tightly packed during the first month of postnatal development. Here, we report that the packing of AChRs into postsynaptic aggregates was reduced in 4‐week postnatal mice that had reduced amounts of the AChR‐associated protein, rapsyn, in the postsynaptic membrane (rapsyn+/− mice). We hypothesize that nerve‐derived agrin increases postsynaptic expression and targeting of rapsyn, which then drives the developmental increase in AChR packing. Neural agrin treatment elevated the expression of rapsyn in C2 myotubes by a mechanism that involved slowing of rapsyn protein degradation. Similarly, exposure of synapses in postnatal muscle to exogenous agrin increased rapsyn protein levels and elevated the intensity of anti‐rapsyn immunofluorescence, relative to AChR, in the postsynaptic membrane. This increase in the rapsyn‐to‐AChR immunofluorescence ratio was associated with tighter postsynaptic AChR packing and slowed AChR turnover. Acute blockade of synaptic AChRs with α‐bungarotoxin lowered the rapsyn‐to‐AChR immunofluorescence ratio, suggesting that AChR signaling also helps regulate the assembly of extra rapsyn in the postsynaptic membrane. The results suggest that at the postnatal neuromuscular synapse agrin signaling elevates the expression and targeting of rapsyn to the postsynaptic membrane, thereby packing more AChRs into stable, functionally‐important AChR aggregates. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008
Systemic IFN‐α drives kidney nephritis in B6.Sle123 mice
Authors: Fairhurst Anna‐Marie , Mathian Alexis , Connolly John E. , Wang Andrew , Gray Hillery F. , George Tiffany A. , Boudreaux Christopher D. , Zhou Xin J. , Li Quan‐Zhen , Koutouzov Sophie , Banchereau Jacques , Wakeland Edward K. 
Published: May 2008

AbstractThe impact of IFN‐α secretion on disease progression was assessed by comparing phenotypic changes in the lupus‐prone B6.Sle1Sle2Sle3 (B6.Sle123) strain and the parental C57BL/6 (B6) congenic partner using an adenovirus (ADV) expression vector containing a recombinant IFN‐α gene cassette (IFN‐ADV). A comprehensive comparison of cell lineage composition and activation in young B6 and B6.Sle123 mice revealed a variety of cellular alterations in the presence and absence of systemic IFN‐α. Most IFN‐α‐induced phenotypes were similar in B6 and B6.Sle123 mice; however, B6.Sle123 mice uniquely exhibited increased B1 and plasma cells after IFN‐α exposure, although both strains had an overall loss of mature B cells in the bone marrow, spleen and periphery. Although most of the cellular effects of IFN‐α were identical in both strains, severe glomerulonephritis occurred only in B6.Sle123 mice. Mice injected with IFN‐ADV showed an increase in immune complex deposition in the kidney, together with an unexpected decrease in serum anti‐nuclear antibody levels. In summary, the predominant impact of systemic IFN‐α in this murine model is an exacerbation of mechanisms mediating end organ damage.
Hemin Modified Carbon Fat Electrode for Analyzing Antimalarial Endoperoxide Artemisinin in Artemisia annua
Authors: Debnath Chhanda , Saha Pijus , Ortner Astrid 
Published: June 2008

AbstractA hemin bulk modified carbon electrode with Adeps neutralis (solid fat) as binder was developed for the determination of antimalarial endoperoxide artemisinin in plant matrix. The hemin modified electrode showed significant catalytic activity for the electrochemical reduction of artemisinin at about −380 mV vs. Ag/AgCl in phosphate buffer solution of pH 7 by using cyclic and differential pulse voltammetry. Under optimized conditions strict linearity between artemisinin concentration and height of the cathodic catalytic current peak was observed in 4.8×10−6–7.8×10−5 M concentration range (R=0.9991) when using differential pulse voltammetry. The detection limit was calculated as 1.4×10−6 M of artemisinin. The developed electroanalytical device is suitable for the determination of artemisinin in Artemisia annua extracts.
Time‐distributed effect of exposure and infectious outbreaks
Authors: Naumova Elena N. , MacNeill Ian B. 
Published: June 2008

AbstractExtreme weather affects the timing and intensity of infectious outbreaks, the resurgence and redistribution of infections, and it causes disturbances in human‐environment interactions. Environmental stressors with high thermoregulatory demands require susceptible populations to undergo physiological adaptive processes potentially compromising immune function and increasing susceptibility to infection. In assessing associations between environmental exposures and infectious diseases, failure to account for a latent period between time of exposure and time of disease manifestation may lead to severe underestimation of the effects. In a population, health effects of an episode of exposure are distributed over a range of time lags. To consider such time‐distributed lags is a challenging task given that the length of a latent period varies from hours to months and depends on the type of pathogen, individual susceptibility to the pathogen, dose of exposure, route of transmission, and many other factors. The two main objectives of this communication are to introduce an approach to modeling time‐distributed effect of exposures to infection cases and to demonstrate this approach in an analysis of the association between high ambient temperature and daily incidence of enterically transmitted infections. The study is supplemented with extensive simulations to examine model sensitivity to response magnitude, exposure frequency, and extent of latent period. Copyright © 2008 John Wiley & Sons, Ltd.
WCDMA downlink capacity of cigar‐shaped microcells for underground metro service
Authors: Ahmed Bazil Taha 
Published: May 2008

AbstractIn this paper, the wideband code division multiple access (WCDMA) downlink capacity and the interference statistics of underground cigar‐shaped microcells utilised to serve users within metros are analysed. The hybrid model of propagation is used in the analysis where a model of eight cigar‐shaped microcells is used. The downlink capacity is given for different sector radioR, train lengthLtrain, break point distanceRband propagation parameters (sand γ). It is found that increasing the sector range up to 1250 m will increase the sector downlink capacity. Also, it is found that the effect of changing the value of the propagation parametersis very small. It is noticed that increasing the train lengthLtrainwill increase the downlink capacity. Also, it is noticed that, increasing the propagation parameter γ will reduce the sector downlink. Finally, it is found that, the effect of changing the break point distanceRbis quasi‐null. Copyright © 2008 John Wiley & Sons, Ltd.
Analysis and design of OFDM‐IDMA systems
Authors: Tong Jun , Guo Qinghua , Ping Li 
Published: June 2008

AbstractThis paper deals with the analysis and design of orthogonal frequency‐division multiplexing interleave‐division multiple‐access (OFDM‐IDMA). We begin with the analysis of the information‐theoretical advantages of non‐orthogonal transmission schemes in fading multiple‐access channels. We then turn attention to practical design issues. A signal‐to‐noise ratio (SNR) evolution technique is developed to predict the bit‐error‐rate (BER) performance of OFDM‐IDMA. This technique is applied to system design and optimisation. Through proper power allocation, OFDM‐IDMA can achieve the multi‐user gain (MUG) predicted by information‐theoretical analysis. It is also an attractive option in compensating for the clipping effect caused by peak‐power limitation. Numerical examples show that OFDM‐IDMA can (i) alleviate the PAPR problem commonly suffered by OFDM‐based schemes; (ii) deliver significant MUG compared with other orthogonal alternatives; (iii) provide robust communications in frequency‐selective channels; and (iv) support high single‐user throughput. Copyright © 2008 John Wiley & Sons, Ltd.
A theories‐based systemic framework for evaluating diverse portfolios of scientific work, part 1: Micro and meso indicators
Authors: Jordan Gretchen B. , Hage Jerald , Mote Jonathon 
Published: May 2008

AbstractRecently, several articles have argued for changes in the kinds of evaluation being conducted for research, technology, and development (RTD) programs. Among other suggestions, these are of special merit: (1) a more macro and systemic focus, (2) concentrating on the processes of generating innovation, (3) using theory to guide the RTD evaluation, and (4) identifying blockages and obstacles. The authors put forth a multilevel, theories‐based framework of indicators for RTD evaluations that addresses these suggestions and is a guide for policy makers in policy formulation and reformulation.© Wiley Periodicals, Inc.
A peer review process for games and software
Authors: Mallon Bride 
Published: May 2008

AbstractA peer‐review process for assessing the contribution of artifacts, such as games and software to research, is proposed. Games and software produced as research output by academics tend to be accredited within their institution through discussion of the artifact, rather than directly. An independent judg‐ment by peers confirming an artifact's contribution of something new, concep‐tually or practically, to a discipline can then be used by academics as evidence in secondary research appraisals, such as promotion appraisals or research assessment exercises, an example being the United Kingdom's Research Assessment Exercise. © Wiley Periodicals, Inc.
Evaluation of large research initiatives: Outcomes, challenges, and methodological considerations
Authors: Quinlan Kathleen M. , Kane Mary , Trochim William M. K. 
Published: May 2008

AbstractThe authors synthesize relevant literature and findings of evaluations of four large‐scale, federally funded scientific research programs in the United States to identify desired outcomes of these types of programs, major evaluation chal‐lenges, and methodological principles and approaches. Evaluators face numer‐ous contextual, political, and methodological challenges in evaluating big science. The authors propose that these may be addressed through participatory planning, such as concept mapping, triangulation of evidence, use of promising methodologies, and a systems approach. © Wiley Periodicals, Inc.
Making team science better: Applying improvement‐oriented evaluation principles to evaluation of cooperative research centers
Authors: Gray Denis O. 
Published: May 2008

AbstractThe rise of the research center has changed the landscape of U.S. research enter‐prise. It has also created a number of evaluation challenges, particularly when considering strategically focused, multifaceted cooperative research centers (CRCs). The author argues that although recent CRC evaluation efforts have gone a long way toward meeting the needs of groups interested in accountabil‐ity, they do little to meet the needs of inexperienced scientist managers who try to lead and manage these organizationally complex initiatives. An exception to this trend is described: the improvement‐oriented evaluation strategy pio‐neered by the National Science Foundation IUCRC program. © Wiley Period‐icals, Inc.
Mass and size distribution of firebrands generated from burning Korean pine (Pinus koraiensis) trees
Authors: Manzello Samuel L. , Maranghides Alexander , Shields John R. , Mell William E. , Hayashi Yoshihiko , Nii Daisaku 
Published: May 2008

AbstractThe present study reports on a series of real‐scale fire experiments that were performed to determine the mass and size distribution of firebrands generated from Korean Pine (Pinus koraiensis), a common conifer species indigenous to China, Japan, and Korea. The experiments were performed at the Building Research Institute in Tsukuba, Japan. The total tree height was fixed at 4.0 m and tree moisture content was varied to examine the influence that this parameter has on the mass and size distribution of the firebrands that are produced, under ambient wind conditions. The firebrands were collected using an array of pans. The pans used for firebrand collection were filled with water. This ensured that firebrands would be quenched as soon as they made contact with the pans. The firebrands were subsequently dried and the mass and size of more than 500 firebrands were measured. The Korean pine trees were also mounted on load cells during burning to determine the temporally resolved mass loss profiles. The mass loss data were used to compare the total amount of mass collected as firebrands with the total amount of mass burned. Results of this study are presented and compared with the mass and size distribution of firebrands collected from burning Douglas‐fir trees, a conifer tree species indigenous to the U.S.A. Copyright © 2008 John Wiley & Sons, Ltd.
Determination of permeability in fibrous porous media using the lattice Boltzmann method with application to PEM fuel cells
Authors: Van Doormaal Mark A. , Pharoah Jon G. 
Published: June 2008

AbstractThe lattice Boltzmann method (LBM) is used to simulate the flow through an idealized proton exchange membrane fuel cell (PEMFC) porous transport layer (PTL) geometry generated using a Monte Carlo method. Using the calculated flow field, Darcy's law is applied and the permeability is calculated. This process is applied in both through‐ and in‐plane directions of the paper as both of these permeability values are important in computational fluid dynamics models of PEMFCs.It is shown that the LBM can be used to determine permeability in a random porous media by solving the flow in the microstructure of the material. The permeability in the through‐ and in‐plane directions is shown to be different and the anisotropic nature of the geometry creates anisotropic permeability. It is also found that fiber arrangement plays a large role in the permeability of the PTL. New correlations are presented for in‐ and though‐plane permeabilities of fibrous porous media with (0.6<ε<0.8). Copyright © 2008 John Wiley & Sons, Ltd.