bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mass spectrometric studies on pyridine‐piperazine‐containing ligands and their complexes with transition metals formed in solution
Authors: Nuutinen Jari M. J. , Purmonen Mikko , Ratilainen Jari , Rissanen Kari , Vainiotalo Pirjo 
Published: September 2002

AbstractElectrospray ionization (ESI) and matrix‐assisted laser desorption/ionization (MALDI) methods were used to study open‐chain piperazine‐containing ligands (L) and their complexes formed with transition‐metal salts. ESI and MALDI measurements were performed with a Fourier transform ion cyclotron resonance (FT‐ICR) and a time‐of‐flight (TOF) mass spectrometer, respectively. Only singly charged complexes, between one ligand and one or several metal ions, were formed in the ESI measurements. Because the net charge was always one, one or several counterions were attached to the complex. Under ESI conditions, the complexes formed between the ligands and metal (Co, Ni, Cu, and Cd) salts were [L + M + X]+, [L + H + M + X2]+ and [L + M2 + X3]+ (M = metal ion, X = counterion). In collision induced dissociation reactions the [L + H + M + X2]+ complexes easily eliminated one proton and one counterion. Fragmentation pathways were more dependent on the metal ion than the ligand, and elimination of the second counterion occurred with one proton from copper and nickel complexes and with one proton and one hydrogen from cobalt complexes. Differences in the fragmentation of the complexes could be due to electronic configuration of the metal ion. In the MALDI measurements the ratio between the [L + H]+ and [L − H]+ ions varied with the matrix. Fragmentation of the ligands through elimination of 2‐methylpyridine end groups occurred with the aromatic matrices containing carboxylic acid and hydroxyl substituents. Ionization of the complexes was not successful with MALDI as the matrix molecules were also attached to the complexes. Copyright © 2001 John Wiley & Sons, Ltd.
Protection of fixed service receivers from the interference produced by the non‐geostationary satellites in a fixed satellite service network: a statistical interference analysis
Authors: Fortes José Mauro P. , Maldonado Jorge E. Amores 
Published: September 2002

AbstractUntil 1997, the power flux density (pfd) limits applicable to fixed satellite service (FSS) satellite transmitters to protect fixed service (FS) receivers operating in the same frequency band were those in Article 21 of the radio regulations. They were developed assuming that potentially interfering satellites in the FSS would only operate in the GSO. The need to revise these limits to allow for the protection of FS receivers from interference generated by non‐geostationary satellites has led to several studies, most of them based on the non‐realistic assumption that every visible satellite in a NGSO constellation produces the maximum allowed pfd level at the FS receive station location. To provide a quantitative indication of how pessimistic this assumption is, this paper considers a more realistic model in which the pfd entries reaching a given FS receiver location are characterized by statistically independent random variables. The probability density functions of these random variables depend on the operational characteristics of the NGSO network. The obtained results have also shown the need to consider some of the operational characteristics of NGSO satellite networks when evaluating the interference produced by their satellites. If these operational characteristics are not taken into account in the calculations, higher values of interference, that do not reflect the real interference environment, are obtained. Copyright © 2002 John Wiley & Sons, Ltd.
Electroluminescence spectra study of Au/Si/SiO2 superlattice/p‐Si structures with gamma irradiation
Authors: Ma S. Y. , Qin G. G. , Wang Y. Y. , He D. Y. , Liu X. Q. 
Published: September 2002

AbstractVisible light emission can be observed from alternation‐magnetron‐sputtered Si/SiO2 superlattices (SSOSLs) when the forward bias exceeds 5 V. The electroluminescence (EL) spectra of Au/ amorphous Si/SiO2 superlattice/p‐Si structures with Si layers of nine different thicknesses showed a peak located at 650 nm. After the SSOSLs were irradiated by a 60Co radiative source, a new strong 470 nm blue peak emerged from the EL spectra in all the Au/ Si/SiO2 superlattice/p‐Si structures. We rule out the possibility that both the excitation and recombination processes of the observed EL are from the nanometre silicon layers, as described by the quantum confinement model. The experimental results can be explained by electrons from the Au electrode and holes from the p‐Si substrate tunnelling into the luminescence centres in the SiO2layers and recombining radiatively there. Copyright © 2001 John Wiley & Sons, Ltd.
Local conductivity study of TiO2 electrodes by atomic force microscopy
Authors: Jiang Feng Zhi , Zhang Dong She , Lin Yuan , Song Yan Lin , Xiao Xu Rui , Jiang Lei , Zhu Dao Ben 
Published: September 2002

AbstractTitanium dioxide (TiO2) nanocrystalline porous film electrodes were prepared by the sol–gel method on indium–tin oxide (ITO) glass and chemically modified further by an aqueous solution of titanium tetrachloride for solar energy conversion application. The surface topography and local conductivity of the TiO2 films were investigated by atomic force microscopy and a simultaneous current mapping technique in the dark and under ultraviolet illumination, respectively. It was found that the conductivity of the films was improved by chemical treatment and the possible mechanism of the effect was discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Ultrathin Al layers on Si(111) and Si(100): structures and phase transitions
Authors: Gröger R. M. , Barczewski M. R. 
Published: September 2002

AbstractThe metal/silicon system Al/Si(111)‐7 × 7 was studied by our group with spot‐profile analysis low‐energy electron diffraction (SPA‐LEED), reflection high‐energy electron diffraction (RHEED) and scanning force microscopy (SFM), with emphasis on temperature‐dependent order–disorder phase transitions of the surface structures. A review of the Al/Si(111) system describes our results in context with the findings of others. An improved phase formation diagram, including earlier results, is deduced. Between the submonolayer phases and the thick films a cluster phase (the δ‐phase) was found that exists in a coverage range of 1–10 monolayers, showing intriguing temperature‐dependent effects. At coverages above 20 monolayers the behaviour changes to that of thick films. Although the Al/Si(100) system has completely different reconstructions below one monolayer, the same δ‐phase as on Si(111) appears at one monolayer, with similar thermal behaviour. Copyright © 2001 John Wiley & Sons, Ltd.
Row structure in metal‐induced Si(111) surface reconstructions
Authors: Jin Kui‐juan , Sanders Barry C. , Pan Shao‐hua , Yang Guo‐zhen 
Published: September 2002

AbstractWe demonstrate that quantum size effects play a crucial role in the row structure of metal‐induced Si(111) reconstruction by identifying the ‘magic’ widths of the metal adsorbates with the minima of electron energy as a function of adsorbate width. Without any adjustable parameters, we obtain accurate agreement with all recent results for Si(111)‐4 × 1‐In and Si(111)‐3 × 1‐M (M = Li, Na, K, Rb, Ag) structures. This new and simple physical picture of electron energies in metal adsorbates provides a universal quantitative model for describing the row structures of metal‐induced Si(111) surface reconstructions. Copyright © 2001 John Wiley & Sons, Ltd.
Chain‐length‐adjusted assembly of substituted porphyrins on graphite
Authors: Wang Hongna , Wang Chen , Zeng Qingdao , Xu Shandong , Yin Shuxia , Xu Bo , Bai Chunli 
Published: September 2002

AbstractA series of alkyloxyphenyl‐substituted porphyrins were synthesized, and their adsorption and assembling behaviour on a highly oriented pyrolytic graphite (HOPG) surface were studied by scanning tunneling microscope (STM) in ambient conditions. A characteristic stripe‐like structure was observed from these samples. In high‐resolution images, we found that within the stripe structure porphyrin cores are arranged side by side with each other and the alkyl chains interdigitate to form a uniform alkane lamella. This high stability and close‐packed assembly is attributed to van der Waals interactions between the alkyl chains and the graphite substrate, which substantially increases the desorption barrier of the combined molecules. This observation illustrates that molecular alkylation is an effective method to obtain stable low‐dimensional molecular assemblies. Copyright © 2001 John Wiley & Sons, Ltd.
Molecular dynamics study for structural stability of the interface at elevated temperatures
Authors: Zhao S. J. , Wang S. Q. , Ye H. Q. 
Published: September 2002

AbstractThe high‐temperature structure of the Σ = 5 bicrystalline interface of B2 NiAl with a large boundary plane is investigated by molecular dynamics simulations on parallel computers. It is observed that the atoms in the grain boundary region tend to form clusters in a thermal structural disorder transition, which is initiated at a temperature well below the thermodynamic melting point Tm (∼0.52 Tm). The number and size of the clusters are monitored over a wide temperature range including Tm. Below Tm, the number and size of the clusters increase continuously with increasing temperature. When the temperature is up to Tm, the abrupt growth of the clusters induces melting. Once above Tm, the number and size of the clusters decrease significantly upon raising the temperature. The calculations of the potential energy also indicate that the thermal disorder transition is a continuous process, in contrast to the first‐order melting transformation. Copyright © 2001 John Wiley & Sons, Ltd.
Effects of surface physicochemical properties on the tribological properties of liquid paraffin film in the nanoscale
Authors: Shen Mingwu , Luo Jianbin , Wen Shizhu 
Published: September 2002

AbstractEffects of different coatings on the tribological properties of very thin oil films in the nanoscale were investigated. The film thickness and friction force were measured by the technique of relative optical interference intensity (ROII) and a stress–strain force measuring system with high precision. The results indicate that the film thickness complies with the elastohydrodynamic theory in the high‐speed region but it differs from the theory in the low‐speed region. The physicochemical properties of coating surfaces have a great effect on the tribological properties of the oil film in the nanoscale. The coating with higher surface energy gives rise to a thicker film and a higher friction coefficient. The reasons for enhancement in the friction coefficient of the oil film in the nanoscale are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Chemical structure and interface reaction of LaCoO3/Si thin‐film system
Authors: Zhang Yingxia , Zhu Yongfa , Ye Xiaoyan , Cao Lili 
Published: September 2002

AbstractAn LaCoO3 thin film was prepared on Si(111) substrate successfully using an amorphous heteronuclear complex, LaCo(DTPA)·6H2O, as a precursor. The surface chemical structures and interface reaction of LaCoO3/Si thin film were studied by XPS and AES techniques. The AES depth profile analysis indicated that the composition of the LaCoO3 thin film was relatively homogeneous with depth. Interface diffusion and chemical reaction took place at the interface between the LaCoO3 layer and the Si substrate during thermal treatment. The linear least‐squares fitting of the AES depth profile analysis indicated that the LaCoO3 decomposed into simple a oxide of La and Co at the interface. An SiO2 species also formed at the interface when the sample was treated at relatively high temperature. Interface diffusion and reaction were intensified with increasing calcination temperature and time. When the temperature was <650 °C, the interface species were mainly La2O3 and CoO simple oxides. After the temperature reached 700 °C, the interface species were La2O3, CoO and SiO2. Copyright © 2001 John Wiley & Sons, Ltd.
Transmission electron microscopy studies of microstructures of silica–zirconia membranes for gas separation
Authors: Kato T. , Sasaki Y. , Osada K. , Hirayama T. , Saka H. 
Published: September 2002

AbstractTwo types of silica–zirconia amorphous membranes were synthesized on the outer surface of porous alumina supports using the sol–gel method. The molar ratios of ZrO2 in SiO2 were 15 and 25 mol.%, respectively. Transmission electron microscopy (TEM) specimens of the membranes were prepared in a focused ion beam system. The microstructural characterizations were achieved by TEM and the chemical compositions of the amorphous material were analysed by energy‐dispersive x‐ray spectroscopy (EDX). Structural investigation of both membranes using TEM revealed two structures: continuous pores ∼100 nm in diameter in the amorphous material filling the crevices of the porous alumina supports; and layered structures of amorphous film on the porous alumina support formed by the coating process. Because the former structure has such large continuous pores, gases should be separated in the layered amorphous film. Therefore, the amorphous film on the porous alumina support should play the most important role in the gas separation mechanism. Furthermore, Zr/Si ratios of those amorphous films were revealed by TEM and EDX. They were constant for the 15% ZrO2–SiO2 membrane but not constant for the 25% ZrO2–SiO2 membrane. Copyright © 2001 John Wiley & Sons, Ltd.
Environmental dependence of thermal oxidation behaviour of silicon nanocrystallites
Authors: Zhu Y. , Ong P. P. 
Published: September 2002

AbstractThree kinds of nanosilicon crystallites were prepared by different methods in high vacuum. All of them were composed of tiny silicon crystallites that initially were only mildly oxidized before annealing, but their behaviour upon annealing in a vacuum differed substantially, depending on the environment in which they resided. X‐ray photoelectron spectroscopy analyses revealed that the unencapsulated nanoparticles tended to oxidize quite quickly, whereas the nanoparticles sandwiched between layers of Al2O3 matrices were oxidized very slowly even under intense annealing. In the zinc/silicon nanocrystalline mixture, oxidation of the Si0 state was even faster than that of the intermediate Si +1,+2 and +3 states. Both the stability and formation processes of the Si O bonds in the partially oxidized states differed considerably with different environmental surroundings. However, in all cases, the Si O bonds of the fully oxidized Si+4 state remained the most stable, to which the less oxidized states tend to gravitate eventually. Copyright © 2001 John Wiley & Sons, Ltd.
Adhesion activation of Twaron® aramid fibres studied with low‐energy ion scattering and x‐ray photoelectron spectroscopy
Authors: de Lange P. J. , Akker P. G. , Maas A. J. H. , Knoester A. , Brongersma H. H. 
Published: September 2002

AbstractThe properties of the interphase between Twaron® aramid fibres and polymer matrix systems can be optimized by a surface treatment process of the fibres. In this work, x‐ray photoelectron spectroscopy and low‐energy ion scattering have been used to analyse the surface layers, whereas the adhesion was measured by a bundle pull‐out experiment. From the results, we succeeded in establishing a relation between the surface treatment, the resulting chemical/elemental surface composition and the adhesion to an epoxy matrix. Copyright © 2001 John Wiley & Sons, Ltd.
Probing the ex situ morphology of Ge islands on Si(001): AFM and XPS inelastic peak shape analysis
Authors: Cohen Simonsen A. , Tougaard S. , Hansen J. L. , Nylandsted Larsen A. 
Published: September 2002

AbstractThe dependence of morphology on growth temperature for Ge islands on Si(001) is studied ex situ using XPS inelastic peak shape analysis and atomic force microscopy (AFM). A systematic study is performed with temperatures of 200 °C, 550 °C and 700 °C and Ge nominal coverages of 5, 10 and 20 Å. By peak shape analysis of the Ge 2p and Si KLL spectra, islanding is found and the average island morphology is characterized quantitatively. The island morphology shows systematic trends with both temperature and Ge coverage. At fixed Ge dosage, increasing substrate temperature leads to taller and narrower islands, whereas for fixed temperatures both the island height and width increase with increasing Ge dosage. By AFM, the island morphology is resolved laterally and the size distribution of islands is found to depend strongly on temperature. Correlating the AFM and XPS results shows that they are complementary and consistent. Oxidation of the nanostructures is investigated by core‐level chemical shifts and the in‐depth distribution of oxygen is determined. There is substantial Ge oxidation and essentially no Si oxide is found. Copyright © 2001 John Wiley & Sons, Ltd.
Visualization of reconstituted solenoid chromatin structure by tapping mode atomic force microscopy
Authors: Liu Dage , Wang Chen , Li Junwei , Wang Zhigang , Xu Bo , Wei Zhongqing , Lin Zhang , Qin Jingfen , Cao Enhua , Bai Chunli 
Published: September 2002

AbstractIn this paper, tapping mode atomic force microscopy was applied to visualize the higher order chromatin structure reconstituted from calf thymus DNA and calf thymus whole histone in vitro. All the revealed reconstituted chromatin structures consisted of similar well‐defined subunits. In some of the chromatin structures, four to six subunits per turn were wrapped right‐handed to form a flattened solenoid with a height distribution of 12 ± 2 nm; and the other Y‐ and V‐shaped chromatin structures were formed by aggregation of these solenoids, which presented similar heights as the solenoids. Typical atomic force microscopy (AFM) images revealed relatively regular solenoid structure (containing six nucleosomes per turn) with a ratio of diameter to pitch of 3 : 1, which is in good agreement with that of 30 : 11 in the chromatin solenoid model proposed by Finch and Klug. Bio‐gel elution was used to separate reconstituted chromatin from uncombined histone particles, which proved to be helpful for the AFM imaging of the higher order chromatin structure with nearly no disturbance of histone particles and salt in the background. The AFM observations showed that the higher order chromatin structure was preserved well enough during the bio‐gel elution process. The cause for the stability of higher order chromatin structure during the bio‐gel elution was analysed. Electron microscopy analysis and circular dichroism spectroscopy investigation of the DNA–histone complexes indicated the formation of ordered aggregates. Copyright © 2001 John Wiley & Sons, Ltd.
Learning across the life cycle: Experimentation and performance among the hollywood studio heads
Authors: Miller Danny , Shamsie Jamal 
Published: September 2002

AbstractGuided by notions from the literature on organizational learning, this paper investigates how product line experimentation and organizational performance change across the careers of top managers. Its subjects are the studio heads who ran all the major Hollywood film studios from 1936 to 1965. The study found first, that product line experimentation declines over the course of executive tenures; second, that there is an inverse U‐shaped relationship between top executive tenure and an organization's financial performance; and third, that product line experimentation is more likely to benefit financial performance late in top executives' tenures. These findings are consistent with a three‐stage ‘executive life cycle’. During the early years of their tenures, top managers experiment intensively with their product lines to learn about their business; later on their accumulated knowledge allows them to reduce experimentation and increase performance; finally, in their last years, executives reduce experimentation still further, and performance declines. Copyright © 2001 John Wiley & Sons, Ltd.
Llun—a high‐level debugger for generated parsers
Authors: Glass S. , Ince D. , Fergus E. 
Published: September 2002

AbstractParser generators such as yacc have been used in a large number of applications, not just those that involve compiler writing. This has meant that these tools are being used increasingly by nonspecialist developers. A consequence of this is that good support is required for debugging a grammar and its generated parser(s). This paper describes Llun, a debugging tool that visualizes the operation of a generated parser at both a high‐level and a low‐level. Llun is superior to other parser visualization products by virtue of the high‐level facilities it offers. The paper describes some of the problems encountered using parser generators, outlines a visualization system which addresses a number of the problems and uses a taxonomy developed by Price to categorize the system. Copyright © 2001 John Wiley & Sons, Ltd.
Investigation of genotoxic effect of taxol plus radiation on mice bone marrow cells
Authors: Özkan Lütfi , Egeli Ünal , Tunca Berrin , Aydemir Nilüfer , Çeçener Gülşah , Akpinar Gürler , Ergül Emel , Çimen Çiğdem , Özuysal Sema , Kahraman‐Çetintaş Sibel , Engin Kayihan , Ahmed Mansoor M. 
Published: September 2002

AbstractIn this study, we investigated the genotoxic effect of taxol, radiation, or taxol plus radiation on highly proliferative normal tissue‐bone marrow cells of Swiss albino mice. Swiss‐albino mice, 3–4 months old, were used in this study. Taxol was administered bolus intravenously through the tail vein. Radiation was given by using a linear accelerator. There were four treatment categories, which had a total of 34 groups. Each group consisted of five animals. The first was the control category that had one group (n = 5). The second treatment category was taxol alone, which had three groups as per taxol dose alone (n = 15). The third treatment category was radiation alone, which had three groups as per the radiation dose (n = 15). The fourth treatment category was taxol plus radiation, which had 27 groups as per combined radiation dose plus taxol dose concentration and as per pre‐treatment timing sequence of taxol before radiation (n = 135). Mice were sacrificed 24 h after taxol or radiation or combined administration using ether anesthesia. The cells were then dropped on two labeled slides, flamed, air dried, and stained in 7% Giemsa; 20–30 well‐spread mitotic metaphases were analyzed for each animal; the cells with chromosome breaks, acentric fragments, and rearrangements were evaluated on ×1,000 magnification with light microscope (Zeiss axioplan). The mitotic index was determined by counting the number of mitotic cells among 1,000 cells per animal. Differences between groups were evaluated with Student’s t‐test statistically. Taxol caused a dose‐dependent increase in chromosomal aberrations (P = 0.027). Similarly, radiation caused a dose‐dependent increase in chromosomal aberrations (P = 0.003) and decreased mitotic index (P = 0.002). In combination, there were a small enhancements at the 40 mg/kg taxol dose level and at 0.25 and 0.5 Gy radiation doses in the 48 h group. However, an increase in chromosomal aberrations was observed after 48 hours of taxol exposure when compared 12 or 24 h of taxol exposure (P = 0.001 and P = 0.019). These findings suggest that taxol at the high doses with low dose radiation caused radiosensitizing effect in bone marrow cells. Forty‐eight‐hour pretreatment of taxol exposure followed by radiation caused significant induction of chromosomal aberrations and a reduction of mitotic index when compared to other taxol timing sequence. Teratogenesis Carcinog. Mutagen. 22:1–11, 2002. © 2002 Wiley‐Liss, Inc.