bluuebunny/crossref_metadata_2025_split huggingface dataset:
Theoretical studies of structures and stabilities of a new odd‐numbered fullerene dimer: C141
Authors: Gao Xingfa , Yuan Hui , Chen Zhenling , Zhao Yuliang 
Published: October 2004

AbstractThe possible isomers of a newly synthesized C141 molecule are calculated using MNDO, AM1, PM3, B3LYP/3‐21G, and B3LYP/6‐31G(d) methods. The geometry optimizations showed that the isomer 8‐8 has the lowest total energy in all 64 possible structures of C141. Unlike those of C130, C140, etc., the C141 8‐8 shows a new structure: two C70 side cages open [6.6] ring junctions located at the equator (instead of cap) area to create new chemical bonds for the bridge atom. Theoretical measurements of the average length of the long and short axes of C70 side cages in the C141 molecule reveal that when two C70 cages are connected with each other at the equators, their geometric shapes become more spherical compared with the pristine C70; this leads to a reduction of the molecular polarizability. Analysis of the local and global strain indicates that the global strain of C70 monomer in the C141 8‐8 is greatly reduced compared to the pristine C70. The stable C70 derivatives that are formed with reacted CC bonds in the equator area may put new insights into fullerene chemistry, in particular, for C70 to react with a large molecule. The results are discussed together with the experimental data. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 2023–2030, 2004
A hybrid method of molecular dynamics and harmonic dynamics for docking of flexible ligand to flexible receptor
Authors: Tatsumi Rie , Fukunishi Yoshifumi , Nakamura Haruki 
Published: October 2004

AbstractWe have developed a new docking method to consider receptor flexibility, a hybrid method of molecular dynamics and harmonic dynamics. The global motions of the whole receptor were approximately introduced into those of the receptor in the docking simulation as harmonic dynamics. On the other hand, the local flexibility of the side chains was also considered by conventional molecular dynamics. We confirmed that this new method can reproduce the fluctuations of the whole receptor by making a comparison of the directions and amplitudes of the global fluctuations. Then this method was applied to the docking of HIV‐1 protease and its ligand. As a result, we observed a docking process where the ligand enters into the binding pocket well, which implies that this method is effective enough to reproduce a molecular complex formation. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 1995–2005, 2004
Evolution and features of global land June–August dry/wet periods during 1920–2000
Authors: Shi Neng , Chen Luwen 
Published: October 2004

AbstractDry/wet features for the globe and the Northern and Southern Hemispheres are investigated in terms of 1920–2000 June–August (JJA) global land precipitation data. The weighted mean JJA precipitation anomaly index and the weighted mean JJA dry/wet area index are used to describe the extent of global dryness/wetness. It is pointed out that 1988 (1930) was the globally wettest (driest) year in 1920–2000, and 1954 (1976) was the second wettest (driest). The dryness/wetness of the globe and Northern and Southern Hemispheres has shown distinctive interdecadal changes: during the 1920s, global dryness occurred in JJA frequently; from the 1920s to the 1940s global wetness occurred infrequently in JJA; the 1950s–1960s was a period of frequent global JJA wetness; and the 1970s to 2000 was a period of frequent global JJA dryness/wetness, with the number of dry years greater than that of wet years. The dry/wet features of the Northern Hemisphere are comparatively consistent with those of the globe, but there is no obvious relation between JJA mean precipitation anomalies of the two hemispheres. The analyses of the simultaneous and last winter sea‐surface temperature anomalies of global dry/wet years reveal that there is clear correlation of JJA global dry/wet change with sea‐surface temperature variations and El Niño–southern oscillation (ENSO) events. Global JJA dryness occurs when the summer ENSO (El Niño) is weaker, and global JJA wetness occurs when the summer ENSO is strong. The largest difference between the last winter sea‐surface temperature fields for global dry and wet years is that the sea‐surface temperature in the North Pacific and North Atlantic for wet years is substantially higher than that for dry years. Copyright © 2004 Royal Meteorological Society
A new analysis of variability and predictability of seasonal rainfall of central southern Africa for 1950–94
Authors: Mwale Davison , Yew Gan Thian , Shen Samuel S. P. 
Published: October 2004

AbstractUsing wavelet analysis and wavelet‐based empirical orthogonal function analysis on scale‐averaged‐wavelet power and individual scale power, we identified the non‐stationary sea‐surface temperature (SST) fields of the South Atlantic and Indian Oceans that are associated with coherent regions of rainfall variability in central southern Africa (CSA). The dominant mode of CSA rainfall is out of phase between the coastal areas and the centre of CSA and has been decreasing consistently since 1970. The frequencies associated with this mode are between 2–2.4 and 5.6–8 years. The Benguela ocean current SSTs form the dominant spatial pattern of the South Atlantic Ocean, and the Brazil and Guinea ocean current SSTs form the second leading mode. The Benguela spatial patterns were found to migrate seasonally between Africa's west coast and South America's east coast. The northern Indian Ocean SST forms the leading mode of variability, followed by the south Indian Ocean SST. Using predictor fields identified from both oceans, we achieved encouraging results of predicted CSA rainfall using a non‐linear statistical teleconnection artificial neural network–genetic algorithm model. At 3 month lead time, correlations of between 0.8 and 0.9, root‐mean‐square errors of between 0.4 and 0.9 and Hansen Kuipers skill scores of between 0.4 and 0.8 were obtained between observed and predicted CSA rainfall. Copyright © 2004 Royal Meteorological Society
The effect of concurrent sea‐surface temperature anomalies in the tropical Pacific and Atlantic on Caribbean rainfall
Authors: Spence Jacqueline M. , Taylor Michael A. , Chen A. Anthony 
Published: October 2004

AbstractSingular value decomposition (SVD) techniques are used to deduce a relationship between rainfall over the Caribbean basin and oppositely signed sea‐surface temperature anomalies in the Pacific and Atlantic. The analysis is done for four 3 month seasons. The first two seasons: November–January (NDJ) and February–April (FMA) encompass the Caribbean dry period, and the other two, May–July (MJJ) and August–October (ASO), include the early and late Caribbean rainy seasons. The first SVD mode for all seasons represents variability due to El Niño–southern oscillation (ENSO) and, with the exception of the later wet season, the second SVD mode represents variability due to tropical North Atlantic sea‐surface temperatures. ENSO has the greatest impact during the late rainfall season (ASO) and the early dry season (NDJ), whereas the tropical Atlantic controls variability in the early rainfall season (MJJ). The configuration of concurrent but oppositely signed sea‐surface temperature anomalies in the tropical Pacific and Atlantic basins is only associated with rainfall modification in the late Caribbean rainfall season (ASO) and the early Caribbean dry season (NDJ). Copyright © 2004 Royal Meteorological Society
Interdecadal and interannual variations of annual and extreme precipitation over central‐northeastern Argentina
Authors: Penalba Olga C. , Vargas Walter M. 
Published: October 2004

AbstractLong, annual precipitation time series from central‐northeastern Argentina are analysed with special attention to interdecadal and interannual variations. The results show a variability that is highly nonstationary. The most outstanding feature is the difference in annual precipitation before and after the 1950s. The interdecadal variability is particularly well defined in the west, and there is a significant linear trend in the study area. Negative anomalies of the areal‐averaged annual precipitation can be observed in all the areas around 1910 and 1930 or 1940. In the western zone there are two better‐defined negative periods around 1950 and 1970, and a gradual increase can be observed in the eastern zones starting in the 1950s. The interdecadal and interannual variations affect the behaviour of extreme precipitation on the annual scale and during the months with maximum precipitation in the region. In support of these conclusions, different representation methods are used (running means, power spectrum analysis, and wavelet transforms). The variations in the annual cycle of extreme precipitation under different conditions are analysed by applying harmonic analysis. The wettest years are represented by an annual and semi‐annual cycle, whereas dry years need the input of lower frequency cycles. Copyright © 2004 Royal Meteorological Society
Characteristics, evolution and mechanisms of the summer monsoon onset over Southeast Asia
Authors: Zhang Zuqiang , Chan Johnny C. L. , Ding Yihui 
Published: October 2004

AbstractBased on the 1979–95 mean pentad reanalysis data from the US National Centers for Environmental Prediction, the climatological characteristics and physical mechanism of the Asian summer monsoon (ASM) onset are investigated. Special focus is given to whether the ASM onset starts earlier over the Indochina Peninsula than over the South China Sea (SCS) and why the ASM is established the earliest over Southeast Asia.An examination of the composite thermodynamic and dynamic quantities confirms that the ASM onset commences earliest over the Indochina Peninsula, as highlighted by active convection and rainfall resulting from the convergence of southwesterly flow from the Bay of Bengal (BOB) vortex and easterly winds associated with the subtropical anticyclone over the SCS. Two other important characteristics not previously noted are also identified: the earliest reversal of meridional temperature gradient throughout the entire troposphere and the corresponding establishment of an easterly vertical wind shear, which are due to upper level warming caused by eddy (convective) transport of latent heat.These changes in the large‐scale circulation suggest that, in addition to rainfall, a reversal in the planetary‐scale circulation should be included in determining the timing of the ASM onset. With such a consideration, the climatological ASM onset occurs first over southeastern BOB and southwestern Indochina Peninsula in early May, and then advances northeastward to reach the SCS by the fourth pentad of May (16–20 May). The monsoon then covers the entire Southeast Asia region by the end of May. Subsequently, a similar onset process begins over the eastern Arabian Sea, India and western BOB, and the complete establishment of the ASM over India is accomplished in mid June. In the process of the onset of each ASM component, the reversal of the upper level planetary‐scale circulation depends strongly on that of the meridional temperature gradient. Over the Indochina Peninsula, the seasonal transition of upper level temperature results from convection‐induced diabatic heating, whereas over western Asia it is attributed to subsidence warming induced by the active ascending motion over the former region.The steady increase in surface sensible heating over the Indian subcontinent and the latent heating over the tropical Indian Ocean in April to early May appear to be the major impetus for the development of the cyclonic vortex over the BOB. A similar enhancement over the Arabian Peninsula and the surrounding regions is also identified to be crucial to the development of the so‐called onset vortex over the Arabian Sea, and then ultimately to the ASM onset over India. Copyright © 2004 Royal Meteorological Society
The near‐surface wind field over the Antarctic continent
Authors: van Lipzig N. P. M. , Turner J. , Colwell S. R. , van Den Broeke M. R. 
Published: October 2004

AbstractA 14 year integration with a regional atmospheric model has been used to determine the near‐surface climatological wind field over the Antarctic ice sheet at a horizontal grid spacing of 55 km. Previous maps of the near‐surface wind field were generally based on models ignoring the large‐scale pressure‐gradient forcing term in the momentum equation. Presently, state‐of‐the‐art atmospheric models include all pressure‐gradient forcing terms. Evaluation of our model output against in situ data shows that the model is able to represent realistically the observed increase in wind speed going from the interior to the coast, as well as the observed wind direction at South Pole and Dumont d'Urville and the bimodal wind distribution at Halley. Copyright © 2004 Royal Meteorological Society
Novel methods of automated structure elucidation based on 13C NMR spectroscopy
Authors: Meiler Jens , Köck Matthias 
Published: October 2004

AbstractThree new approaches for automated structure elucidations of organic molecules using NMR spectroscopic data were introduced recently. These approaches apply a neural network 13C NMR chemical shift prediction method to rank the results of structure generators by their agreement of the predicted and experimental chemical shifts. These three existing implementations are compared using realistic example molecules. The applicability and reliability of such approaches is addressed. Copyright © 2004 John Wiley & Sons, Ltd.
Circulant preconditioners for solving singular perturbation delay differential equations
Authors: Jin Xiao‐Qing , Lei Siu‐Long , Wei Yi‐Min 
Published: October 2004

AbstractWe consider the solution of singular perturbation delay differential equations (SPDDEs) by using boundary value methods (BVMs). These methods require the solution of some nonsymmetric, large and sparse linear systems. The GMRES method with the Strang‐type block‐circulant preconditioner is proposed for solving these linear systems. We prove that if anA,‐stable BVM is used for solving a system of SPDDEs, then our preconditioner is invertible and the eigenvalues of the preconditioned system are clustered. When the GMRES method is applied to the preconditioned systems, the method would converge fast. Numerical results are given to show the effectiveness of our methods. Copyright © 2004 John Wiley & Sons, Ltd.
Virtual microscopy for learning and assessment in pathology
Authors: Kumar Rakesh K , Velan Gary M , Korell Sami O , Kandara Madan , Dee Fred R , Wakefield Denis 
Published: October 2004

AbstractVirtual slides are high‐magnification digital images of tissue sections, stored in a multi‐resolution file format. Using appropriate software, these slides can be viewed in a web browser in a manner that closely simulates examination of glass slides with a real microscope. We describe the successful implementation of teaching microscopic pathology with virtual slides and, for the first time, their use in summative assessment. Both students and teaching staff readily adapted to the use of virtual microscopy. Questionnaire feedback from students strongly indicated that virtual slides solved a number of problems in their learning, while providing good to excellent image quality. A deliberate policy of allocating two students per workstation promoted collaboration and helped to maintain interest in microscopic pathology. The use of a secure browser facilitated assessment using virtual slides, with no technical or security issues arising despite high peak demand. The new Medicine programme at the University of New South Wales will exclusively utilize virtual microscopy for the study of both histology and histopathology. We believe that the use of high‐quality learning resources such as virtual slides can ensure that microscopic examination of tissues remains both meaningful and interesting. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Abnormal PcG protein expression in Hodgkin's lymphoma. Relation with E2F6 and NFκB transcription factors
Authors: Sánchez‐Beato Margarita , Sánchez Esther , García Juan F , Pérez‐Rosado Alberto , Montoya María C , Fraga Mario , Jesús Artiga M , Navarrete Mercedes , Abraira Víctor , Morente Manuel , Esteller Manel , Koseki Haruhiko , Vidal Miguel , Piris Miguel A 
Published: October 2004

AbstractThe Polycomb group (PcG) of proteins comprises a family of repressors of homeobox genes that play key roles in body formation, haematopoiesis and cell cycle control. In this study, a large‐scale analysis of PcG protein expression (BMI1, MEL18, PH1, RNF2, RING1, and RYBP) was performed in 321 Hodgkin's lymphoma (HL) biopsies and in reactive lymphoid tissues using tissue microarrays. The relevance of PcG proteins in HL was also investigated by the simultaneous analysis of PcG and other proteins involved in the control of cell cycle, transcription machinery and lymphoid differentiation. The analysis revealed increased expression of a set of PcG proteins (particularly RYBP and BMI1) in tumour cells in comparison with reactive lymphoid tissue. One of the most striking findings was anomalous RYBP expression in 55% of classical HL cases associated with an unfavourable response to treatment and shorter survival. The data obtained in this study also show an association of PcG proteins with E2F6 and NFκB transcription factors. The statistical relationship between PcG and NFκB activation was further explored in HL‐derived cell lines treated with curcumin, an NFκB inhibitor, and TNFα. Up‐ or downregulation of MEL18 was paralleled by loss or gain of activated NFκB, which suggests that NFκB may regulate expression of this protein. Investigation of the relationship between E2F6 and RING1 by immunofluorescence and confocal analysis, in HL cell lines and paraffin sections, revealed co‐expression of both proteins in the same tumour cells. These results allow us to propose that the formation of transcription complexes with E2F6 may modify the functional status of PcG proteins in HSR cells. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Dual enantioselective Diels–Alder process in the cyclization of chiral acrylamide with dienes
Authors: Jung Doo Young , Park Doo Han , Kim Sung Han , Kim Yong Hae 
Published: October 2004

AbstractDiels–Alder cycloadditions of chiral acrylamides with cyclopentadiene or 2, 3‐dimethyl butadiene proceed with high diastereofacial selectivity. Either endo‐R or endo‐S products have been obtained depending upon the structures of acrylamides and Lewis acids used. The endo form was exclusively obtained over the exo form. The dependence of the mechanism of formation of opposite configurations of endo‐R or endo‐S products on the Lewis acids is discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Atom transfer radical polymerization initiated by N‐bromosuccinimide
Authors: Jiang Jianguo , Zhang Keda , Zhou Hong 
Published: October 2004

AbstractN‐Bromosuccinimide (NBS) was used as the initiator in the atom transfer radical polymerizations of styrene (St) and methyl methacrylate (MMA). The NBS/CuBr/bipyridine (bpy) system shows good controllability for both polymerizations and yields polymers with polydispersity indexes ranging from 1.18 to 1.25 for St and 1.14 to 1.41 for MMA, depending on the conditions used. The end‐group analysis of poly(MMA) and polystyrene indicated the polymerization is initiated by the succinimidyl radicals formed from the redox reaction of NBS with CuBr/bpy. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5811–5816, 2004
Magnetic poly(glycidyl methacrylate) microspheres prepared by dispersion polymerization in the presence of electrostatically stabilized ferrofluids
Authors: Horák Daniel , Benedyk Nataliya 
Published: October 2004

AbstractFine magnetite nanoparticles, both electrostatically stabilized and nonstabilized, were synthesized in situ by precipitation of Fe(II) and Fe(III) salts in alkaline medium. Magnetic poly(glycidyl methacrylate) (PGMA) microspheres with core‐shell structure, where Fe3O4 is the magnetic core and PGMA is the shell, were obtained by dispersion polymerization initiated with 2,2′‐azobisisobutyronitrile (AIBN), 4,4′‐azobis(4‐cyanovaleric acid) (ACVA), or ammonium persulfate (APS) in ethanol containing poly(vinylpyrrolidone) or ethylcellulose stabilizer in the presence of iron oxide ferrofluid. The average microsphere size ranged from 100 nm to 2 μm. The effects of the nature of ferrofluid, polymerization temperature, monomer, initiator, and stabilizer concentration on the PGMA particle size and polydispersity were studied. The particles contained 2–24 wt % of iron. AIBN produced larger microspheres than APS or ACVA. Polymers encapsulating electrostatically stabilized iron oxide particles contained lower amounts of oxirane groups compared with those obtained with untreated ferrofluid. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5827–5837, 2004
Fluorescent poly(aryl ether)s containing benzo[g]phthalazine and benzo[g]isoquinoline moieties
Authors: Kang Ning , Hlil Antisar R. , Hay Allan S. 
Published: October 2004

Abstract2,3‐Bis(4‐fluorobenzoyl)naphthalene was synthesized, and poly(aryl ether)s were prepared through a reaction with various bisphenols in the solvent N,N‐dimethylacetamide in the presence of potassium carbonate. Through a reaction with hydrazine or benzylamine, the corresponding benzo[g]phthalazine or benz[g]isoquinoline was formed. The conversion into heterocyclic structures resulted in a significant straightening of the chains, and the glass‐transition temperatures, inherent viscosities, and apparent molecular weights from size exclusion chromatography were significantly increased, whereas the solubilities decreased. The diketone‐containing polymers were colorless, and the benzo[g]phthalazine‐ and benz[g]isoquinoline‐containing polymers were yellow. The diketone polymers showed strong UV absorption maxima up to 350 nm, with fluorescence emission maxima around 475 nm. The heterocyclic polymers had broad absorptions up to around 450 nm, with strong emission maxima around 550 nm. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5745–5753, 2004
Analytic Solution for Diffusional Filtration across Granular Beds in Low Knudsen Number Regime
Authors: Jung Chang H. , Lee K. W. 
Published: October 2004

AbstractThe collection efficiency of aerosols in the low Knudsen number region was studied using a system of multiple spheres. Kuwabara's free vorticity model was expanded to include the effects of gas slip at the collector surface, with the collection efficiency due to diffusion obtained analytically and compared with existing experimental results. The results showed that the diffusional collection efficiency increases as the Knudsen number increases due to gas slippage at the collector surface. The obtained analytical solution converged to the existing collection efficiency of a solid sphere system with a Knudsen number of zero, and that of a bubble with an infinite Knudsen number. The comparison of the experimental results with analytic solution in this study shows that the trends agree well. Therefore, this study is a subsequent expansion of the collection efficiency in the finite Knudsen number region, and can be used for a broad range of collector sizes, pressures and temperatures.