bluuebunny/crossref_metadata_2025 huggingface dataset:
A new version of the multireference averaged coupled‐pair functional (MR‐ACPF‐2)
Authors: Gdanitz Robert J.
Published: August 2002

The averaged coupled‐pair functional (ACPF), as found in R. J. Gdanitz and R. Ahlrichs, Chem. Phys. Lett. 143 (1988), is probably the most successful method to approximate full configuration interaction (CI) on the multireference (MR) level of theory. However, ACPF has a tendency to slightly overestimate the effect of higher than double substitutions, which, when the zeroth‐order wavefunction is of poor quality, may deteriorate the accuracy or even create instabilities. Since the properties of the ACPF and similar methods have apparently not always been correctly described in the literature, we repeat the derivation of this method in some detail. We analyze the connection between the (original) ACPF and the similar averaged quadratic coupled cluster (AQCC) method (which may be regarded as a damped ACPF), on one hand, and the different versions (0–3) of the coupled electron‐pair approximation (CEPA), on the other hand. We find that ACPF and AQCC may be regarded as CEPA‐1, respectively, CEPA‐3, where the shifts of the Hamiltonian are substituted by a single averaged shift. As CEPA‐3 considerably underestimates correlation effects, AQCC shows the same behavior. However, when the zeroth‐order wavefunction is of poor quality, AQCC may be more stable and thus more accurate than ACPF. By analyzing the role of the single substitutions, we find that ACPF may especially overestimate their contribution to unlinked clusters like \documentclass{article}\pagestyle{empty}\begin{document}$\textstyle\frac{1}{2}\hat{T}^{2}_{1}$\end{document}. We therefore propose a new version, called ACPF‐2, where (in contrast to AQCC) only the renormalization factor, g, that corresponds to the singles, is damped; i.e., we have (4/N)[1−1/(2N−2)]. In the limit of a large number of electrons, N, this factor becomes two times as large as in the (original) ACPF, where 2/N is used. In order to test the new ACPF‐2 method, we perform numerous comparisons with full CI, as well as calculations including terms that are linear in the interelectronic distances, rij. We find that in difficult cases, ACPF‐2 is of similar stability as is AQCC and is thus considerably more accurate than the original ACPF. In contrast to AQCC, however, ACPF‐2 achieves this stability without sacrificing the high accuracy which is obtained by ACPF in well‐behaved cases. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Computer modeling of C2 cluster addition to fullerene C60
Authors: Budyka Mikhayl F. , Zyubina Tatyana S. , Ryabenko Alexander G.
Published: August 2002

The reaction between C2 cluster and C60 fullerene resulting in C2 insertion to C60 with formation of closed C62 cage (reaction of C2 ingestion by C60) was investigated by the semiempirical MNDO‐PM3 method. The geometries and energies of extremal points on the C62 potential energy surface were calculated. Several reaction pathways leading to the formation of three different closed C62 fullerenes were investigated. All insertion reactions proceed stepwise through intermediate adducts of different structures. The main reaction pathways were found to be addition of C2 by its one side to the 6,6‐ or 5,6‐bond of C60 with formation of primary unclosed C62 adducts of “ball‐with‐fork” structures, lying in deep potential wells. Back reaction of C2 detachment from primary adducts can compete with that of their transformation to the closed C62 cages inasmuch as calculated activation barriers of the both reactions are comparable. Model calculations at the B3LYP/6‐31G* level, using C32H12 semisphere instead of C60, confirmed the conclusion about two competitive pathways of the primary adducts transformation, C2 detachment, and C2 ingestion. The concerted insertion of C2 to C60 was realized only in the case of severe restrictions on starting geometry of the C2 + C60 system. The results of calculations explain recent experimental data on the formation of metastable adducts upon addition of C2 to C60, obtained using the time‐of‐flight mass spectrometer with laser desorption. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Configuration interaction calculation of electronicgtensors in transition metal complexes*
Authors: Neese Frank
Published: August 2002

An algorithm for the calculation of electronicgtensors from configuration interaction (CI) wave functions and its implementation for any ground‐state spinSis described. The algorithm can be used together with either single‐ or multireference CI wave functions but assumes a spatially nondegenerate ground state. A one‐electron approximation to the spin–orbit coupling (SOC) operator is used. Presently the implementation uses the INDO/S model of Zerner and coworkers. Results are presented for a representative collection of Cu(II) complexes with N‐, O‐, and S‐containing ligands. The calculations reproduce the trends in the experimental data well and show no systematic errors. For the test set thegvalues are reproduced with a standard deviation of 0.021. The method has therefore a good cost–performance ratio and is expected to be helpful in chemical and biochemical applications. Further improvements are feasible and necessary and are briefly discussed. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 83: 104–114, 2001
Long‐range effects in optimizing the geometry of stereoregular polymers—IV: Explicit determination of the helical angle
Authors: Jacquemin Denis , Champagne Benoît
Published: August 2002

We study the converging behavior of the analytical gradient of the energy per unit cell with respect to the helical angle in stereoregular polymers. Similarly to the other forces (with respect to nuclei coordinates or unit cell length), this gradient presents unique particularities. A technique based on multiple Taylor expansions is developed in order to evaluate accurately and directly the long‐range contributions to this gradient. These LR contributions have analytical characteristics similar to the one of the stress‐tensor, although the latter presents diverging sums. The method is tested on model system and is shown to be extremely efficient, allowing great improvement in accuracy at a negligible cost. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Substituent effects on the physical properties and pKa of phenol
Authors: Gross Kevin C. , Seybold Paul G.
Published: August 2002

Substituent effects on the physical properties and pKa of phenol were studied using density functional theory [B3LYP/6‐311G(d,p)] calculations. Substituents alter the physical properties of phenol such as the hydroxyl‐group CO and OH bond lengths, the C OH bond angle, and the energy barrier to rotation about the C O bond, and also influence the hydroxyl‐group pKa. Except for the rotational barrier, Hammett σ constants showed strong correlation with these property changes. Several quantum chemical parameters, including the natural charge on the phenolic hydrogen Qn(H) and the natural charge on the phenoxide oxygen Qn(O−), the HF/6‐311G(d,p) HOMO energy Ehomo, and the proton‐transfer energy ΔEprot, outperformed the empirical Hammett constants in modeling changes in the pKa. All of these latter parameters yielded correlation coefficients ∣r∣>0.94 for the pKa. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Computer simulation of cluster assembling
Authors: Duque F. , Mañanes A. , Molina L. M. , López M. J. , Alonso J. A.
Published: August 2002

Density functional theory is used to investigate the assembling of metallic clusters to yield stable or metastable cluster solids. Motivated by the observed high stability of the Al13H cluster, which has a substantial highest occupied and lowest unoccupied molecular orbitals (HOMO–LUMO) gap, we have modeled the assembling of those clusters. For a favorable relative orientation of each cluster with respect to all its neighbors, a cluster solid is predicted and its structure appears to be stable at least up to 150 K, which is the highest temperature in our simulations. We have also studied the chemical bonding in the stoichiometric solid alloys PbA, where A is one of the alkali elements Na, K, Rb, or Cs. Those crystals exist in an ordered phase formed by tetrahedral Pb4 clusters surrounded by the alkali atoms. The study of this family of natural cluster compounds reveals the coating role played by the cations, providing further insight into the favorable conditions required for the formation of cluster solids. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
On the influence of nuclear fluctuations on calculated NMR shieldings of benzene and ethylene: a Feynman path integral–ab initio investigation*
Authors: Böhm Michael C. , Schulte Joachim , Ramírez Rafael
Published: August 2002

The absolute magnetic shieldings of benzene and ethylene have been theoretically studied under the conditions of thermal equilibrium, i.e., under explicit consideration of the nuclear degrees of freedom. For this purpose we have combined the Feynman path integral quantum Monte Carlo (PIMC) formalism with the gauge‐including atomic orbital (GIAO) approach in the Hartree–Fock (HF) approximation. The HF operator has been employed to derive the NMR parameters of the two hydrocarbons via an ensemble averaging over large sets of molecular configurations that are populated in thermal equilibrium. The nuclear fluctuations are responsible for a deshielding of the nuclei relative to the shieldings at the vibrationless minimum of the potential energy surface (PES). The influence of the nuclear degrees of freedom is largest for the isotropic part of the13C shielding tensor. The theoretical results can be explained on the basis of simple geometrical considerations. The bond lengths in thermal equilibrium are larger than the bond lengths at the minimum of the PES. This length enhancement is the prerequisite for a deshielding of the nuclei in thermal equilibrium. The vibrational corrections of the nuclear magnetic resonance (NMR) parameters of benzene and ethylene are quantum driven; classical thermal degrees of freedom of the nuclei are of minor importance. Conceptual problems of theoretical studies of NMR parameters on the basis of a single molecular geometry are emphasized. The influence of the spatial uncertainty of the nuclei becomes decisive in molecules with light atoms. It is pointed out that the combination of the PIMC formalism with electronic Hamiltonians of state‐of‐the‐art quality renders possible accurate determinations of NMR parameters. © 2002 John Wiley & Sons, Inc. Int J Quantum Chem 86: 280–296, 2002
Ultra‐fast gradient vs. fast isocratic chromatography in bioanalytical quantification by liquid chromatography/tandem mass spectrometry
Authors: Romanyshyn Leslie , Tiller Philip R. , Alvaro Raul , Pereira Antonio , Hop Cornelis E. C. A.
Published: August 2002

Liquid chromatography/tandem mass spectrometry (LC/MS/MS) methods developed for quantification using rapid (‘ballistic’) gradients on narrow bore, short HPLC columns have been previously described by this laboratory. This paper compares the fast gradient approach with the more traditional high‐organic isocratic LC/MS/MS methods. The comparison is based on an analysis of the effectiveness of the chromatographic separations when using the two approaches (i.e. k′, N, and W). The data presented herein are derived from actual biological samples analyzed as part of the drug discovery process. Copyright © 2001 John Wiley & Sons, Ltd.
A new technique for unbiased external ion accumulation in a quadrupole two‐dimensional ion trap for electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry
Authors: Belov Mikhail E. , Nikolaev Evgenii N. , Alving Kim , Smith Richard D.
Published: August 2002

External ion accumulation in a two‐dimensional (2D) multipole trap has been shown to increase the sensitivity, dynamic range and duty cycle of a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. However, it is important that trapped ions be detected without significant bias at longer accumulation times in the external 2D multipole trap. With increasing ion accumulation time pronounced m/z discrimination was observed when trapping ions in an accumulation quadrupole. In this work we show that superimposing lower rf‐amplitude dipolar excitation over the main rf‐field in the accumulation quadrupole results in disruption of the m/z discrimination and can potentially be used to achieve unbiased external ion accumulation with FTICR. Copyright © 2001 John Wiley & Sons, Ltd.
Improved low‐energy electron injection systems for high rate electron capture dissociation in Fourier transform ion cyclotron resonance mass spectrometry
Authors: Tsybin Youri O. , Håkansson Per , Budnik Bogdan A. , Haselmann Kim F. , Kjeldsen Frank , Gorshkov Michael , Zubarev Roman A.
Published: August 2002

New low‐energy electron injection systems based on indirectly heated dispenser cathodes facilitate electron capture dissociation (ECD) in Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. In this joint report, details are presented of the design and performance of these systems on two commercial FTICR instruments, 9.4 T Bruker BioAPEX in Uppsala and 4.7 T IonSpec Ultima in Odense. New results include obtaining meaningful one‐scan MS/MS data for isolated precursor ions with millisecond irradiation times. The ECD rate improvement is not only due to the larger total electron current, but the larger emitting area as well. Copyright © 2001 John Wiley & Sons, Ltd.
Description and validation of a staggered parallel high performance liquid chromatography system for good laboratory practice level quantitative analysis by liquid chromatography/tandem mass spectrometry
Authors: King Richard C. , Miller‐Stein Cynthia , Magiera Daniel J. , Brann John
Published: August 2002

The Aria LX4 staggered parallel high performance liquid chromatography (HPLC) system is evaluated for application to good laboratory practice (GLP) level quantitative analysis by liquid chromatography/tandem mass spectrometry (LC/MS/MS). This system consists of four fully independent binary HPLC pumps, a modified autosampler, and a series of switching and selector valves all controlled by a single computer program. The system improves sample throughput without sacrificing chromatographic separation or data quality. Validation results for four different compounds, each analyzed on a separate channel of the Aria system, show precision and accuracy equivalent to that required of a single‐channel system. The results show that sample throughput can be increased nearly four‐fold without requiring significant changes in current analytical procedures. The flexibility and ease of use of the Aria system suggest that it should be possible to quickly implement it in any analytical LC/MS/MS environment. Copyright © 2001 John Wiley & Sons, Ltd.
Comparison of the positive and negative ion electrospray mass spectra of some small peptides containing pyroglutamate
Authors: Boontheung Pinmanee , Brinkworth Craig S. , Bowie John H. , Baudinette Russell V.
Published: August 2002

The positive ion electrospray mass spectra of [M + H]+ and the negative ion electrospray mass spectra of [M − H]− ions of selected pyroglutamate containing peptides both provide sequencing data. The negative ion spectra show the normal α and β backbone cleavages in addition to δ and γ backbone cleavages initiated by the side chains of Glu and Phe residues. For example, the [M − H]− ion of pGlu Pro Gln Val Phe Val‐NH2 shows δ and γ peaks at m/z 224 (δ, Gln3), 244 (γ, Phe4), 451 (δ, Phe4), 471 (γ, Gln3). Some of the negative ion spectra show unusual grandaughter peaks that originate by α and β, or δ and γ backbone cleavages of a β1 cleavage ion. Copyright © 2002 John Wiley & Sons, Ltd.
Self‐esterification of fulvic acid model compounds in methanolic solvents as observed by electrospray ionization mass spectrometry
Authors: McIntyre Cameron , McRae Christopher , Jardine Daniel , Batts Barry D.
Published: August 2002

The self‐esterification of two fulvic acid model compounds in methanolic solvents was studied by electrospray ionization mass spectrometry (ESI‐MS). The strongly acidic tetrahydrofurantetracarboxylic acid rapidly self‐esterified to form mono‐ and dimethyl esters when stored in methanol, even at reduced temperatures. The weakly acidic analogue, cyclopentanetetracarboxylic acid, reacted minimally under the same conditions. The use of 50:50 methanol/water as a solvent reduced self‐esterification of the strong acid. However, the presence of water promoted the formation of multiply charged ions in the ESI mass spectra. The use of water and 50:50 acetonitrile/water as solvents eliminated self‐esterification but the mass spectra still contained multiply charged ions. This study implies that the use of methanolic solvents with humic substances may compromise analytical data through the formation of methyl esters. Copyright © 2002 John Wiley & Sons, Ltd.
Some aspects of matrix‐assisted laser desorption/ionization analysis of hemoglobin from whole human blood
Authors: Bajuk Anna , Michalak Leszek
Published: August 2002

Some aspects of the matrix‐assisted laser desorption/ionization (MALDI) method in the analysis of hemoglobin from whole human blood are described. These aspects are: sensitivity of this method, fragmentation of hemoglobin ions, and influence of some impurities (sodium chloride NaCl, sodium sulfate Na2SO4, and potassium ferrocyanide K4Fe(CN)6) on the detection process. As a matrix, α‐cyano‐4‐hydroxycinnamic acid (CCA) was used. The estimated maximum concentrations of tested salts for which no hemoglobin signal was observed were determined. Copyright © 2002 John Wiley & Sons, Ltd.
Non‐nucleoside inhibitors of herpesviruses
Authors: Wathen Michael W.
Published: August 2002

While the treatment of herpes simplex virus with acyclovir and similar nucleoside analogues was one of the first success stories in antiviral chemotherapy, substantial unmet medical needs remain for herpesvirus diseases. In particular, the increasing numbers of immunosuppressed people due to AIDS, transplantation, cancer and aging has driven the need for improved antivirals to treat diseases caused by human cytomegalovirus (HCMV). Currently available drugs for the treatment of HCMV diseases are less than ideal agents due to issues of toxicity, modest efficacy and poor oral bioavailability. High throughput screening of large compound collections for inhibitors of specific viral enzymes or inhibition of viral growth in cell culture have identified a number of new HCMV inhibitors at several pharmaceutical companies. These compounds act by inhibition of novel molecular targets such as the viral protein kinase, viral protease and viral proteins involved in DNA cleavage/packaging. In addition, novel non‐nucleoside inhibitors of the herpesvirus DNA polymerase have recently been described. This review will summarise some of these research efforts and will focus on non‐nucleoside compounds that directly inhibit a viral process. Copyright © 2002 John Wiley & Sons, Ltd.
Hindrances to upstream migration of atlantic salmon (Salmo salar) in a northern Swedish river caused by a hydroelectric power‐station
Authors: Rivinoja Peter , McKinnell Skip , Lundqvist Hans
Published: August 2002

Many Baltic salmon rivers have lost their natural juvenile production due to human activities blocking or reducing access to their spawning grounds, e.g. damming, power generation, partial hinders, etc. One such hindrance is a hydroelectric complex located in the lower reaches of River Umeälven in northern Sweden. Water from the forbay created by the dam Norrfors is directed to the Stornorrfors power‐station. At times, 100% of the river water is directed to the power‐station. Water from the power‐station then flows via a tunnel and outlet channel to the river. From the point of the tunnel's discharge into the river, the old river bed acts as a bypass channel directing migrating adult fish to a fish ladder located at the base of the dam.

In this study, the effect that an additional turbine, that was installed at the power‐station in 1986, had on fish passage run‐time was examined. Changes in run‐time were compared for two periods 1974–1985 and 1986–1995. In 1997, 55 wild and 25 hatchery salmon were captured in the Umeälven estuary, radio tagged with uniquely coded tags, and tracked upstream. Both manual and automatic loggers were used to locate fish daily. The main findings show that only 26% of the wild salmon and none of the hatchery salmon found the fish ladder. It is suggested that the salmon followed the main water discharge from the power‐station outlet and are thus directed away from the entrance to the bypass channel leading to the fish ladder. Salmon respond by moving upstream or downstream depending on the current flow regimes. The bypass channel consists of partial hinders that may explain why it takes on average 52 days for the salmon to migrate 32 km from the estuary to the fish ladder. Adding a fourth turbine at the power‐station did not appear to have changed the timing of the migration or the seasonal distribution of the migrating wild salmon through the fish ladder. There was no significant effect of the fourth turbine on the duration of the middle 50% of the run in any weight‐class for wild salmon. Daily turbine discharges or ambient water temperature and daily counts of wild salmon at the fish ladder were not related. Copyright © 2001 John Wiley & Sons, Ltd.
Performance evaluation of adaptive routing algorithms in packet‐switched intersatellite link networks
Authors: Mohorčič Mihael , Švigelj Aleš , Kandus Gorazd , Werner Markus
Published: August 2002

This paper addresses the performance evaluation of adaptive routing algorithms in non‐geostationary packet‐switched satellite communication systems. The dynamic topology of satellite networks and variable traffic load in satellite coverage areas, due to the motion of satellites in their orbit planes, pose stringent requirements to routing algorithms. We have limited the scope of our interest to routing in the intersatellite link (ISL) segment. In order to analyse the applicability of different routing algorithms used in terrestrial networks, and to evaluate the performance of new algorithms designed for satellite networks, we have built a simulation model of a satellite communication system with intersatellite links. In the paper, we present simulation results considering a network‐uniform source/destination distribution model and a uniform source–destination traffic flow, thus showing the inherent routing characteristics of a selected Celestri‐like LEO satellite constellation. The updates of the routing tables are centrally calculated according to the Dijkstra shortest path algorithm. Copyright © 2002 John Wiley & Sons, Ltd.
Progression in high school students’ (aged 16–18) conceptualizations about chemical reactions in solution
Authors: Boo Hong‐Kwen , Watson J. R.
Published: August 2002

The purpose of this study was to explore the development over time of students' understandings of the concept of chemical reaction in the context of two familiar reactions in solution. The study is based on interviews of 48 students, aged 16–18, who had been successful in their year 11 examinations and had selected to study chemistry as one of their advanced level subjects in year 12 (age 16–17) and year 13 (age 17–18). All the students were interviewed (on a one‐to‐one basis) twice, once in year 12 and again in year 13, allowing progression in their understanding to be studied. The results show that students made some progress in their understanding of the concept of chemical reaction, but some fundamental misconceptions remained. © 2001 John Wiley & Sons, Inc. Sci Ed 85:568–585, 2001.
Advances in the oxidation resistance of high‐temperature turbine materials
Authors: Smialek James L.
Published: August 2002

This overview highlights some of the key factors in understanding the protective ability of aluminum oxide scales for current gas turbine engine alloys and coatings. Dense, phase‐pure, slow‐growing and adherent scales are required. In most cases, solutions have been found through educated empiricism, with more complete understanding often lagging by decades. Nevertheless, the relentless application of new techniques to answer old questions has often provided radically different viewpoints and pointed the way to new engineering developments. Equally important, this understanding prevents prior misconceptions from taking too strong a hold and maintaining a limited perspective. The microstructure, kinetics, short‐circuit diffusion, phase transformation, growth and residual stresses, interfacial segregation and adhesion provide a richness of topics for this singular and effective system. Copyright © 2001 John Wiley & Sons, Ltd.
Ethical challenges at the beginning of the millennium
Authors: Steinberg Karen K.
Published: August 2002

In the mid‐1980s, the Centers for Disease Control and Prevention (CDC) recognized the need to study genetic risk factors for common diseases such as diabetes and heart disease. To take advantage of a rare opportunity to obtain a nationally representative, population‐based sample to study genetic risk factors, the CDC collected and stored DNA as part of the Third National Health and Nutrition Examination Survey (NHANES III). At the time, the methods for studying these risk factors in large epidemiologic studies were not available. However, in the midst of planning for NHANES III, a revolution was occurring in the field of genetics. The resulting changes would provide a means to realize the goal of explaining why some people are more susceptible than others to risks such as elevated cholesterol or exposure to carcinogens. During this period, ethicists were increasingly asking questions about the safety and risks for participants in genetic research. Was genetic research different from other research? Were new rules for obtaining informed consent for genetic research needed, or should our methods of obtaining informed consent be equally rigorous for all research? When collection of the NHANES III DNA bank was complete in 1994, the CDC and the National Institutes of Health (NIH) held a workshop to address these questions. The published recommendations of this workshop stimulated a national debate that resulted in a significant change in the way genetic epidemiologic research is done in the United States including not only stored biologic specimens but data collected for one purpose but used for another. In 1999, the National Bioethics Advisory Commission (NBAC) published recommendations for the ethical use of human biological materials. The recommendations of the NBAC and policies and practices of the CDC about informed consent for research on stored tissue samples will serve as models for future epidemiologic research. The problems that were recognized in the national debate that ensued and the solutions that followed will affect the way we gain access to biological specimens and data in the 21st century. Published in 2001 by John Wiley & Sons, Ltd.
Assigning time‐linked exposure status to controls in unmatched case‐control studies: alcohol use and nearly lethal suicide attempts
Authors: Kresnow Marcie‐jo , Powell Kenneth E. , Webb Kevin B. , Mercy James A. , Potter Lloyd B. , Simon Thomas A. , Ikeda Robin M. , Frankowski Ralph
Published: August 2002

In case‐control studies, determination of alcohol consumption by cases immediately prior to the injury event is often conceptually straightforward. However, determination of consumption status by controls is difficult because they lack a reference point, especially when cases and controls are not individually matched. We describe a method of assigning alcohol consumption status to controls using a 24‐hour drinking history, the distribution in time of case events, and the random assignment of a specific time period to each control subject. This methodology offers a practical approach for determining alcohol consumption status among control subjects immediately prior to a case event, when controls lack a reference point and have not been individually matched to cases. Published in 2001 by John Wiley & Sons, Ltd.
How to squeeze a lexicon
Authors: Ciura Marcin G. , Deorowicz Sebastian
Published: August 2002

Minimal acyclic deterministic finite automata (ADFAs) can be used as a compact representation of finite string sets with fast access time. Creating them with traditional algorithms of DFA minimization is resource greedy when a large collection of strings is involved. This paper aims to popularize an efficient but little‐known algorithm for creating minimal ADFAs recognizing a finite language, invented independently by several authors. The algorithm is presented for three variants of ADFAs, its minor improvements are discussed, and minimal ADFAs are compared to competitive data structures. Copyright © 2001 John Wiley & Sons, Ltd.
Perioperative radiotherapy for cancer of the esophagus
Authors: Wenz Frederik , Mamon Harvey
Published: August 2002

Carcinomas of the esophagus represent on average about 1% to 2% of all malignant tumors. The incidence shows extreme regional differences, reflecting the established environmental and acquired risk factors for cancer of the esophagus. There has been a major shift in tumor location and histology over the last decades, with the lower third/gastroesophageal junction becoming the most common location and adenocarcinoma the most common histology in white males. There has been a striking improvement in surgical resection rates and operative mortality; however, the curative potential of surgery is likely to be highest in early‐stage disease. The poor prognosis for locally advanced tumors motivated the search for multimodal approaches to improve results. While neither perioperative radiotherapy nor perioperative chemotherapy alone have significantly improved survival rates, combined radiochemotherapy, used as neoadjuvant or definitive therapy, appears more promising. For patients with advanced tumors or extensive nodal involvement, first principles and extrapolation from other tumors of the gastrointestinal tract suggest that a combination of chemotherapy and radiation is likely to be of benefit, as compared to surgery alone. As this treatment is difficult to tolerate in the postoperative setting, neoadjuvant approaches have been emphasized. Although there are promising data, and preoperative chemoradiation is widely utilized, we do not consider the benefit of this approach to have been proven unequivocally. Future progress in the treatment of esophageal cancer may require that systemic therapy be improved to the point where occult metastatic disease can be controlled, enabling the local control provided by surgery and radiation to lead to improved survival. Semin. Surg. Oncol. 20:33–39, 2001. © 2001 Wiley‐Liss, Inc.
Intraoperative radiotherapy for gastrointestinal cancer
Authors: Lehnert Thomas , Treiber Martina , Tiefenbacher Uta , Herfarth Christian , Wannenmacher Michael
Published: August 2002

Local recurrence following potentially curative tumor resection is a major problem in patients with gastrointestinal cancer. To augment surgical excision and to avoid the disadvantages of external beam irradiation, intraoperative radiotherapy (IORT) has been applied to primary and recurrent gastrointestinal cancer, both with curative intent and for palliation. There is ample evidence that the combination of radical surgery and IORT can improve local control. Whether this eventually can translate into improved overall survival has not yet been studied in adequately powered randomized and controlled trials. Semin. Surg. Oncol. 20:40–49, 2001. © 2001 Wiley‐Liss, Inc.
Contemporary role of modern brachytherapy techniques in the management of malignant thoracic tumors
Authors: Harms Wolfgang , Becker Heinrich D. , Krempien Robert , Wannenmacher Michael
Published: August 2002

Sole brachytherapy for carcinoma of the lung is most often performed using high‐dose‐rate (HDR) remote afterloading equipment, which delivers the treatment within the tracheobronchial tree in an outpatient setting. It provides excellent, rapid palliation in advanced stages, and can also be used selectively for curative intent in early stages. In better‐performance patients, fractionated external beam radiation therapy (EBRT) is preferred to brachytherapy as an initial treatment because it appears to provide a modest gain in survival, and more sustained palliation. In patients with centrally located tumors and limited extent of disease, the combination of external and endoluminal irradiation enables curative treatment options. Intraoperative brachytherapy may complement standard adjuvant treatment in incompletely resected, unresectable, or medically inoperable patients, and has the potential to improve local control in selected cases. Due to the rarity of the disease, the role of endoluminal brachytherapy in the treatment regimen of tracheal neoplasms is not yet clearly defined. The risk of fatal bleeding after endoluminal brachytherapy appears to be correlated with tumor localization and fraction size, but in the majority of cases fatal bleeds are caused by progression of local disease. The use of a distanceable applicator provides a central positioning of the source, prevents the delivery of high‐contact doses to the mucosa, and may reduce toxicity. The standard technique for interstitial brachytherapy after breast‐conserving surgery and adjuvant EBRT is the use of low‐dose‐rate (LDR) brachytherapy, but it may also be applied by means of pulsed‐dose‐rate (PDR) or HDR techniques. Prospective trials comparing different boost techniques and indications are needed to define more precisely the subgroup of patients who are most suitable for interstitial brachytherapy. Reirradiation of chest wall local recurrences using brachytherapy molds is effective and provides a high local control rate with acceptable toxicity. Semin. Surg. Oncol. 20:57–65, 2001. © 2001 Wiley‐Liss, Inc.
Mushroom‐derived preparations in the prevention of H2O2‐induced oxidative damage to cellular DNA
Authors: Shi Yu‐ling , James Anthony E. , Benzie Iris F.F. , Buswell John A.
Published: August 2002

Aqueous extracts of the sporophores of eight mushroom species were assessed for their ability to prevent H2O2‐induced oxidative damage to cellular DNA using the single‐cell gel electrophoresis (“Comet”) assay. The highest genoprotective effects were obtained with cold (20°C) and hot (100°C) water extracts of Agaricus bisporus and Ganoderma lucidum fruit bodies, respectively. No protective effects were observed with Mushroom Derived Preparations (MDPs) from Flammulina velutipes, Auricularia auricula, Hypsizygus marmoreus, Lentinula edodes, Pleurotus sajor‐caju, and Volvariella volvacea. These findings indicate that some edible mushrooms represent a valuable source of biologically active compounds with potential for protecting cellular DNA from oxidative damage. Teratogenesis Carcinog. Mutagen. 22:103–111, 2002. © 2002 Wiley‐Liss, Inc.
Oral administration of clomiphene to neonatal rats causes reproductive tract abnormalities
Authors: Nagao Tetsuji , Yoshimura Sinsuke
Published: August 2002

Oral administration of clomiphene at 2, 4, or 8 mg/kg to 4‐day‐old rats caused multiple histopathological abnormalities of the reproductive tract in both male and female animals. No histopathological abnormalities were observed in 30‐day‐old male rats at any dose examined. In contrast, 30‐day‐old females showed hypertrophy of the myometrium at all doses examined, and hypertrophy of the luminal or glandular epithelium, and dilatation of the uterine lumen were observed in the highest dose group. In post‐pubertal rats, histopathologically marked changes were observed in the testes and epididymides in males, and in the ovaries and uterus in females in the highest dose group. In addition, relative weight of male reproductive organs in the highest dose group was decreased as compared with that in the controls. These results suggested that early neonatal exposure to clomiphene induced marked reproductive tract abnormalities in males after puberty, as well as in females. Teratogenesis Carcinog. Mutagen. 21:213–221, 2001. © 2001 Wiley‐Liss, Inc.
Effect of hydrogen peroxide on nitric oxide (NO)‐induced mutagenicity in Salmonella typhimurium
Authors: Saliim Eric T. , Abu‐Shakra Amal
Published: August 2002

Nitric oxide (NO) has been reported to impart, alone or in combination with reactive oxygen species (ROS), the cytotoxicity and putative genotoxicity associated with the immunological response. The present study examined the change in the mutagenic activity profile of the NO‐donor spermine NONOate (SperNO) as a result of introduction of hydrogen peroxide (H2O2) to the Ames assay. The aim was to determine whether the assay could detect H2O2‐induced co‐ or anti‐mutagenic effects on NO‐induced mutagenesis, and the Salmonella typhimurium base‐pair substitution tester strain TA1535 provided an appropriate tool. While TA1535 was shown by the authors and others to be strongly sensitive to NO‐induced mutagenesis, it has also been shown to be insensitive to H2O2‐induced mutagenicity [1,2]. When H2O2 (0.25–4.0 μmol/pl) was added directly to cells treated with SperNO (0.01–1.0 μmol/pl), co‐mutagenicity was not detected, but a drop in reversion count and detectable toxicity was observed, especially at doses > 0.1 μmol/pl. When glucose/glucose oxidase (GOX) or reduced glutathione (GSH) were used as H2O2‐generation systems the results varied. Reversion induced by SperNO (1 μmol/pl) was moderately enhanced by GOX (10–20 mUnits/pl), but the increase albeit reproducible did not reach a doubling (co‐mutagenicity). GOX (40 μmol/pl) induced a reduction in reversion count, but no visible toxicity. On the other hand, GSH (20– 80 μmol/pl) gave a strong co‐mutagenic effect. Co‐mutagenicity was highest (> 5×) at 80 μmol/pl GSH and 0.1 μmol/pl SperNO. Based on these findings, it could be concluded that a) H2O2, when steadily generated in the cell, has a modulatory effect on NO‐mutagenicity, and such a conclusion is not inconsistent with the wide range of responses reported for the two chemicals, and/or b) the observed co‐mutagenic effects of GSH may not be attributable solely to H2O2 generation. Teratogenesis Carcinog. Mutagen. 21:349–359, 2001. © 2001 Wiley‐Liss, Inc.
Acute toxicity modeling of rainbow trout and silver sea bream exposed to waterborne metals
Authors: Liao Chung‐Min , Lin Ming‐Chao
Published: August 2002

Of three proposed acute toxicity models, the uptake–depuration (UD) model, the time‐integrated concentration (TIC) model, and the concentration–time (CT) model are derived and verified with acute toxicity data to estimate the internal residues of waterborne metals in fish as a function of a few constants and variables. The main factors are the exposure time, the external exposure concentration, the bioconcentration factor (BCF), and the depuration rate constant (k2). The UD model is based on the concept of residue levels at the cell membrane well correlating with the whole‐body concentrations, whereas the TIC and the CT models are based on the idea of irreversible inhibition of the enzyme acetylcholinesterase (AChE) governing the metal acute toxicity in that metals in the entire fish or in the aqueous phase can be described by the critical area under the time–concentration curve that is associated with a critical TIC of toxicant in the target tissue. A highly significant correlation (r2>0.9) was found between predictions and LC50(t) data for both the TIC and the CT models, indicating successfully describe 4‐ to 18‐d LC50(t) data of arsenic (As), cobalt (Co), copper (Cu), and Co/Cu mixture in rainbow trout (Oncorhyuchus mykiss) and of Cu in fingerlings and subadults of silver sea bream (Sparus sarba). The time‐dependent lethal internal concentration at the site of action that causes 50% mortality is also predicted for a given compound and species. It concludes that the TIC and the CT models can be applied to regulate the acute toxicity and to estimate incipient LC50 values and internal residues of waterborne metals in fish. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 349–360, 2001
Application‐centric analysis of IP‐based mobility management techniques
Authors: Misra Archan , Das Subir , Agrawal Prathima
Published: August 2002

This paper considers three applications—VoIP, mobile Web access and mobile server‐based data transfers—and evaluates the applicability of various IP‐based mobility management mechanisms. We first survey the features and characteristics of various IP mobility protocols, such as MIPv4, MIPv6, MIP‐RO, SIP, CIP, HAWAII, MIP‐RR and IDMP, and then evaluate their utility on an application‐specific basis. The diversity in the mobility‐related requirements ensures that no single mobility solution is universally applicable. We recommend a hierarchical mobility architecture. The framework uses our Dynamic Mobility Agent (DMA) architecture for managing intra‐domain mobility and multiple application‐based binding protocols for supporting inter‐domain mobility. Thus, we recommend SIP as the global binding protocol for VoIP applications and MIPv4/MIPv6 as the global binding mechanism for the mobile server scenario. Copyright © 2001 John Wiley & Sons, Ltd.
Wind farms connected to weak grids in India
Authors: Sørensen Poul , Unnikrishnan A. K. , Mathew Sajan A.
Published: August 2002

This article describes the mutual influence between the wind turbines and the power quality in the Indian power systems. The Indian power systems are weak in general and the wind energy development has been very fast and concentrated in a few rural areas where the existing transmission and distribution grids are very weak. Therefore the mutual influence between wind turbines and power quality is particularly strong in India. The wind farms influence power quality aspects such as steady state voltage, power factor, flicker and harmonic and interharmonic distortion. The power quality of the grid influences the power performance and safety of the wind turbines and the lifetime of mechanical and electrical components. The findings presented are general for wind farms connected to weak grids, but the Indian case is pronounced concerning weakness of grid as well as wind energy penetration level. Copyright © 2001 John Wiley & Sons, Ltd.
Individual particle characterization of Siberian aerosols by micro‐PIXE and backscattering spectrometry
Authors: Van Malderen H. , Hoornaert S. , Injuk J. , Przybylowicz W. J. , Pineda C. A. , Prozesky V. M. , Van Grieken R.
Published: August 2002

Individual particle analysis using micro‐PIXE and proton backscattering was performed for selected aerosol samples collected over Siberia. Point analyses were complemented by x‐ray mapping for complex particles. Hierarchical cluster analysis of 124 particles identified in general the same particle groups, as found by automated electron microprobe analyses of approximately 25 000 particles from the same locations. However, owing to the superior sensitivity of micro‐PIXE, a number of heavy metals were identified, suggesting an anthropogenic origin of particles. These metals remained undetected by EPXMA owing to its inferior sensitivity. Elemental mapping of single aerosol particles yielded important information on the chemical heterogeneities. Copyright © 2001 John Wiley & Sons, Ltd.
Additional Hepatocellular Carcinomas Undetectable before Surgery
Authors: Shuto Taichi , Hirohashi Kazuhiro , Ikebe Takashi , Mikami Shinichi , Yamamoto Takatsugu , Kubo Shoji , Wakasa Kenichi , Kinoshita Hiroaki
Published: August 2002

The presence of small additional hepatocellular carcinomas (HCCs) undetectable before hepatic resection is a crucial topic for hepatic surgeons. We assessed the incidence of pathologically diagnosed multiple HCCs in 267 patients who underwent hepatic resection for HCC. Ninety‐five additional HCC nodules were detected in 72 of the patients (27%). The survival rate of these 72 patients was significant worse than for the 195 with single nodular HCC (p= 0.0013). Twenty‐one (22%) were detected before surgery, 29 (31%) during surgery, and 45 (47%) on pathologic examination after surgery. The mean nodule diameters for each group were 2.1, 1.0, and 0.9 cm, respectively (p < 0.0001). None of the 21 nodules detected before surgery was well differentiated, whereas 30 of the 74 nodules in the other two groups were well‐differentiated. Although the mean nodule diameter of the well‐differentiated HCC group was the smallest, there was no significant difference among the three groups assigned according to tumor differentiation (p= 0.2355). Altogether, 9 of 16 patients with additional nodules detected before surgery (56%) and 49 of 59 with additional nodules detected during or after surgery (88%) had cirrhosis of the liver. The odds ratio for detecting a new HCC nodule during or after surgery in the presence of cirrhosis was 5.444 (p= 0.0087). Improvement in the detection of small additional HCC nodules before and during surgery and meticulous follow‐up after surgery are necessary for patients with cirrhosis. For patients without cirrhosis, surgical treatment may be performed according to the results of preoperative imaging studies.
Low‐Molecular‐Weight Heparins and Daflon for Prevention of Postoperative Thromboembolism
Authors: Tsimoyiannis Evangelos C. , Floras Grigorios , Antoniou Nikolaos , Papanikolaou Nikolaos , Siakas Philipos , Tassis Andreas
Published: August 2002

The efficacy of low‐molecular‐weight heparins (LMWH) alone versus a combination of Daflon 500 mg with LMWH in preventing postoperative symptomatic thromboembolism was investigated. A total of 1372 patients aged 40 years or older undergoing major abdominal, pelvic, or abdominal wall surgery were randomized into four groups. Group A (n= 591) received enoxoparin 20 mg or fraxiparin 0.3 ml. Group B (n= 595) received the regimens of group A plus Daflon 500 mg. Group C (n= 93) received enoxoparin 40 mg or fraxiparin 0.6 ml. Group D (n= 93) received the regimens of group C plus Daflon 500 mg. Each LMWH was given subcutaneously once a day during the hospitalization and continued in groups C and D for 15 days after discharge (high risk patients). Daflon 500 mg was given as two tablets every 8 hours during the day before surgery, two tablets 6 hours before surgery, and two tablets once a day on postoperative days 4 to 15. Daily clinical examination was performed; and phlebography or perfusion lung scanning (or both) were used in symptomatic patients to confirm deep vein thrombosis (DVT) or pulmonary embolism (PE). The wound was examined on a daily basis for hematomas. The diagnosis of PE was established in two patients of group A and in three patients of group C; symptomatic DVT was established in one patient in group A and three patients of group C. Neither DVT nor PE were established in Daflon 500 mg groups. These data suggest that the combination of Daflon 500 mg and LMWH is more effective than LMWH alone for preventing symptomatic thromboembolism.