bluuebunny/crossref_metadata_2025 huggingface dataset:
Cationic cure of epoxy resin initiated by methylanilinium salts as a latent thermal initiator
Authors: Park Soo‐Jin , Kim Taek‐Jin , Lee Jae‐Rock
Published: August 2002

The effect of the novel N‐crotyl‐N,N‐dimethyl‐4‐methylanilinium hexafluroantimonate (CMH) initiator on cure kinetics and rheological properties of diglycidylether of bisphenol A (DGEBA) epoxy cationic system was investigated. From DSC measurements of the DGEBA/CMH system, it was found that this system exhibited excellent thermal latent characteristics at a given temperature and revealed complex cure behavior as indicated by multiple exotherms. The conversion and conversion rate of the DGEBA/CMH system increased with increasing the concentration of initiator, attributed to the high activity of CMH. Viscoelastic properties during gel formation of DGEBA initiated by CMH were investigated by rheological techniques under isothermal conditions. The gel time obtained from the modulus crossover point t(G′) = G″ was affected by a high curing temperature and the concentration of CMH, resulting in a high degree of network formation in cationic polymerization. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2397–2406, 2001
Cancer and children: where are we coming from? Where are we going?
Authors: Patenaude Andrea Farkas , Last Bob
Published: August 2002

The past four decades have seen remarkable progress in the treatment of childhood cancer and changes in the social environment in which cancer in the family is experienced. Current research in pediatric psycho‐oncology focuses on psychosocial consequences of the disease and on differentiating which factors predict problematic versus positive outcomes in adjustment of the child and the family. The papers in this Special Issue reflect much of the recent developments in childhood psycho‐oncology as well as the challenges to come. Copyright © 2001 John Wiley & Sons, Ltd.
Diabetes mellitus and cystic fibrosis: Comparison of clinical parameters in patients treated with insulin versus oral glucose‐lowering agents
Authors: Rosenecker Joseph , Eichler Irmgard , Bärmeier Heike , von der Hardt Horst
Published: August 2002

The prevalence of cystic fibrosis‐related diabetes melltitus (CFRD) is increasing as patients with cystic fibrosis (CF) live longer. Because patients with CFRD are insulin‐deficient, the standard medical treatment is exogenous insulin. Sulfonylureas enhance insulin secretion by acting on a specific islet beta cell receptor. No data are available about the outcome of sulfonylurea treatment vs. insulin treatment. In this retrospective study, data from 45 patients with CFRD were analyzed regarding their clinical outcome as it related to the treatment protocol.

The duration of DM treatment was 7.6 ± 4.6 years in the insulin‐treated group and 3.5 ± 2.0 years in the sulfonylurea group (n.s.). The age of CFRD diagnosis was significantly earlier in patients treated with insulin (n = 34) than in the patients treated with sulfonylurea (n = 11) (16.4 ± 3.6 vs. 24.2 ± 4.8 years, P < 0.001). No statistical differences were found between the two groups in the time of CF diagnosis, the most recent forced expired volume in 1 sec, forced vital capacity, Shwachman score, hemoglobin A1C levels, or weight for height index at the end of the study.

Our data suggest that a subgroup of CFRD patients can be managed for a number of years with sulfonylurea, and that the clinical outcome was not different in this group compared with the insulin‐treated patients. Pediatr Pulmonol. 2001; 32:351–355. © 2001 Wiley‐Liss, Inc.
Inhibitors of apoptosis proteins in prostate cancer cell lines
Authors: McEleny Kevin R. , Watson R. William G. , Coffey Ronan N.T. , O'Neill Amanda J. , Fitzpatrick John M.
Published: August 2002

BACKGROUND

The caspases are the central executioners of apoptosis. The inhibitors of apoptosis proteins (IAPs) are a family of recently described caspase inhibitors. We hypothesised that tumor resistance to apoptosis could be due in part to IAP expression.

METHODS

The expression of NAIP, cIAP‐1, cIAP‐2, XIAP, and survivin was investigated in the prostate cancer cell lines LNCaP, PC3, and DU145. RNase protection assays and Western blotting were used to assess RNA and protein expression. Apoptotic susceptibility was determined using etoposide and assessed by propidium iodide (PI) DNA incorporation using flow cytometry.

RESULTS

DU145 and PC3 cells were more resistant to apoptosis than LNCaP cells. All the IAPs were identified in the cell lines with variation in IAP expression between different cell types. Immunohistochemistry demonstrated cIAP‐1 expression in PC3 cells was nuclear, while the expression of cIAP‐2 and XIAP was perinuclear. Growing LNCaP cells in charcoal‐stripped or androgen‐supplemented medium resulted in no alteration in IAP expression.

CONCLUSIONS

This study characterises the expression of IAP in three of the most commonly used prostate cancer cells. IAP may make an important contribution to apoptotic resistance in patients with prostate cancer. Prostate 51: 133–140, 2002. © 2002 Wiley‐Liss, Inc.
Androgen ablation promotes neuroendocrine cell differentiation in dog and human prostate
Authors: Ismail A Hazem R. , Landry France , Aprikian Armen G. , Chevalier Simone
Published: August 2002

BACKGROUND

Mechanisms triggering prostatic NE differentiation are poorly understood. Since dog and man naturally develop prostatic proliferative diseases with age, our objectives were to confirm the presence of NE cells in the dog prostate and test their hormonal regulation in both species.

METHODS

Serotonin staining was examined by immunohistochemistry in 37 dog prostates: 17 from intact and 20 from castrated animals. In intact dogs, 9 prostates were normal and 8 hyperplastic. In the castrated group, 6 dogs were left untreated while androgens and estrogens were administered to 7 dogs, each. Human prostates were from 48 prostate cancer patients; half of them were submitted to androgen ablation prior to prostatectomy. The density of serotonin‐positive NE cells was expressed relatively to the number of acini.

RESULTS

Serotonin‐positive NE cells were morphologically similar in dog and human prostates and identified in all groups, independent of the hormonal status. NE cell densities were within the same range in normal and hyperplastic dog prostates but significantly higher after castration. Androgens and estrogens after castration restored NE cell density to normal values and induced luminal differentiation and basal metaplasia, respectively. In human, the density of serotonin‐positive NE cells was also significantly higher in benign glands after androgen ablation.

CONCLUSIONS

The dog is a suitable animal model and mimics the human, since androgen ablation favored prostatic NE differentiation in both species. The down‐regulation elicited by steroids suggests that the process may be reversible and hormonally‐repressed. Prostate 51: 117–125, 2002. © 2002 Wiley‐Liss, Inc.
Progesterone receptor expression in human prostate cancer: Correlation with tumor progression
Authors: Bonkhoff Helmut , Fixemer Thomas , Hunsicker Isabel , Remberger Klaus
Published: August 2002

BACKGROUND

The recent discovery of the classical estrogen receptor alpha (ERα) in metastatic and recurrent prostatic adenocarcinoma suggests that estrogens are implicated in prostate cancer progression.

METHODS

To get more insight into estrogen signaling in prostate cancer tissue, the current study has examined the immunoprofile of the estrogen‐inducible progesterone receptor (PR), and evaluated its relation to ERα gene expression.

RESULTS

In primary tumors, the PR was detectable in 36% of primary Gleason grade 3 (5 of 14 cases), 33% of primary Gleason grade 4 (5 of 15 cases), and in 58% of primary Gleason grade 5 tumors (7 of 12 cases). None of the 41 primary tumors investigated revealed significant PR expression in more than 50% of tumor cells. Conversely, moderate to strong receptor expression was observed in 60% of metastatic lesions (9 of 15 cases), and in 54% of androgen‐insensitive tumors (38 of 71 cases). Irrespective of grades and stages, the presence of the PR was invariably associated with high steady state levels of ERα mRNA, whereas the ERα protein was undetectable by immunohistochemistry (IHC) in a significant number of cases (58 of 97 cases).

CONCLUSIONS

The progressive emergence of the PR during tumor progression obviously reflects the ability of metastatic and androgen‐insensitive tumors to use estrogens through a ERα‐mediated pathway. The present data provide a theoretical background for studying the efficiency of antiestrogens and antigestagens in the medical treatment of advanced prostate cancer. Prostate 48:285–291, 2001. © 2001 Wiley‐Liss, Inc.
Threading structural model of the manganese‐stabilizing protein PsbO reveals presence of two possible β‐sandwich domains
Authors: Pazos Florencio , Heredia Pedro , Valencia Alfonso , de las Rivas Javier
Published: August 2002

The manganese‐stabilizing protein (PsbO) is an essential component of photosystem II (PSII) and is present in all oxyphotosynthetic organisms. PsbO allows correct water splitting and oxygen evolution by stabilizing the reactions driven by the manganese cluster. Despite its important role, its structure and detailed functional mechanism are still unknown. In this article we propose a structural model based on fold recognition and molecular modeling. This model has additional support from a study of the distribution of characteristics of the PsbO sequence family, such as the distribution of conserved, apolar, tree‐determinants, and correlated positions. Our threading results consistently showed PsbO as an all‐beta (β) protein, with two homologous β domains of approximately 120 amino acids linked by a flexible Proline‐Glycine‐Glycine (PGG) motif. These features are compatible with a general elongated and flexible architecture, in which the two domains form a sandwich‐type structure with Greek key topology. The first domain is predicted to include 8 to 9 β‐strands, the second domain 6 to 7 β‐strands. An Ig‐like β‐sandwich structure was selected as a template to build the 3‐D model. The second domain has, between the strands, long‐loops rich in Pro and Gly that are difficult to model. One of these long loops includes a highly conserved region (between P148 and P174) and a short α‐helix (between E181 and N188)). These regions are characteristic parts of PsbO and show that the second domain is not so similar to the template. Overall, the model was able to account for much of the experimental data reported by several authors, and it would allow the detection of key residues and regions that are proposed in this article as essential for the structure and function of PsbO. Proteins 2001;45:372–381. © 2001 Wiley‐Liss, Inc.
Crystallographic dissection of the thermal motion of protein‐sugar complex
Authors: Harata Kazuaki , Kanai Ryuta
Published: August 2002

The crystal structure of turkey egg lysozyme (TEL) complexed with di‐N‐acetylchitobiose (NAG2) was refined at 1.19 Å resolution by the full‐matrix least‐squares method with anisotropic temperature factors, and its thermal motion was evaluated by the TLS method. The average ESDs of atomic parameters of nonhydrogen atoms were 0.030 Å for coordinates and 0.025 Å2 for anisotropic temperature factors. The active site cleft of TEL binds the α‐anomer of NAG2 in a nonproductive binding mode with its pyranose rings parallel to a β‐sheet. The TEL structure was compared with the re‐refined 1.12 Å structure of native TEL. The RMS difference for equivalent Cα atoms was 0.103 Å and a relatively large difference was observed in the region of residues 104–125 rather than in the β‐sheet region where NAG2 was bound. In contrast, the temperature factor of the β‐sheet region was significantly decreased by the NAG2 binding. The TLS model that describes the rigid body motion in translation, libration, and screw motion was adopted for the evaluation of the molecular motion of TEL and NAG2, and the TLS parameters were determined by the least‐squares fit to Uij. The contribution of the external motion of TEL was estimated to be 55.8% of the observed temperature factor for the native structure and 45.9% for the NAG2 complex. The internal motion of TEL represented with atomic thermal ellipsoids was very similar between the native and complex structures except the NAG2 binding region. In the structure of NAG2, the rigid body motion dominates the thermal motion. The center of rotation of NAG2, 4.45Å far from the center of gravity, is on the nitrogen atom of the acetylamino group that is hydrogen bonded to the main‐chain peptide groups of Asn49 and Ala107. The rigid body motion of NAG2 indicates that the acetylamino group is most strongly bound to the active site, and the recognition of this group is a crucial step of the substrate binding. Proteins 2002;48:53–62. © 2002 Wiley‐Liss, Inc.
Structure of the adenovirus E4 Orf6 protein predicted by fold recognition and comparative protein modeling
Authors: Brown Lawrence M. , Gonzalez Ramon A. , Novotny Jiri , Flint S.J.
Published: August 2002

To facilitate investigation of the molecular and biochemical functions of the adenovirus E4 Orf6 protein, we sought to derive three‐dimensional structural information using computational methods, particularly threading and comparative protein modeling. The amino acid sequence of the protein was used for secondary structure and hidden Markov model (HMM) analyses, and for fold recognition by the ProCeryon program. Six alternative models were generated from the top‐scoring folds identified by threading. These models were examined by 3D–1D analysis and evaluated in the light of available experimental evidence. The final model of the E4 protein derived from these and additional threading calculations was a chimera, with the tertiary structure of its C‐terminal 226 residues derived from a TIM barrel template and a mainly α‐nonbundle topology for its poorly conserved N‐terminal 68 residues. To assess the accuracy of this model, additional threading calculations were performed with E4 Orf6 sequences altered as in previous experimental studies. The proposed structural model is consistent with the reported secondary structure of a functionally important C‐terminal sequence and can account for the properties of proteins carrying alterations in functionally important sequences or of those that disrupt an unusual zinc‐coordination motif. Proteins 2001;44:97–109. © 2001 Wiley‐Liss, Inc.
Dynamics and mechanism of ultraviolet photolysis of atrazine on soil surface
Authors: Gong Ajun , Ye Changming , Wang Xingjun , Lei Zhifang , Liu Jianmiao
Published: August 2002

The photolysis of atrazine in the soil surface under UV light and the factors affecting this has been studied. A rate constant of 0.09–0.17 min−1, photolytic depth of 0.1–0.3 mm and half‐life of 4–8 min were determined. The results show that soil granularity, pH, humidity, organic content, humic acid and surface‐active agents could affect the photolysis of atrazine in soil. GC–MS showed three photolytic products: 1‐sec‐butyl‐4,4‐diethyl‐1‐tetrazene, N 2, N 4‐diethyl‐6‐methyl‐1,3,5‐triazine‐2,4‐diamine and 6‐chloro‐N 2‐propyl‐1,3,5‐triazine‐2,4‐diamine. The mechanism of the photolytic process is discussed.

© 2001 Society of Chemical Industry
The aquatic fate of triclopyr in whole‐pond treatments
Authors: Petty David G , Skogerboe John G , Getsinger Kurt D , Foster Dale R , Houtman Bruce A , Fairchild James F , Anderson Lars W
Published: August 2002

The aquatic fate of the triethylamine salt formulation of triclopyr (3,5,6‐trichloro‐2‐pyridinyloxyacetic acid) was determined in whole‐pond applications in closed (no water exchange) systems in California, Missouri and Texas in two studies conducted in 1995 and 1996. These studies determined dissipation rates of triclopyr and its principal metabolites, 3,5,6‐trichloropyridinol (TCP) and 3,5,6‐trichloro‐2‐methoxypyridine (TMP) in water, sediment and finfish. Ponds at each site containing a healthy biological community were treated at 2.5 mg AE litre−1 triclopyr. Water and sediment samples were collected through 12 weeks post‐treatment, and non‐target animals were collected through 4 weeks post‐treatment. Dissipation rates for triclopyr, TCP and TMP were similar at each of the study sites, despite differences in weather, water quality, biotic community, light transmission and geographic location. Half‐lives of triclopyr in water ranged from 5.9 to 7.5 days, while those of TCP and TMP ranged from 4 to 8.8 and 4 to 10 days, respectively. Levels of triclopyr and TCP declined in sediments at half‐lives ranging from 2.8 to 4.6 days and 3.8 to 13.3 days, respectively. No TMP was detected in sediment. Triclopyr and TCP cleared from fish in relation to concentrations found in the water column. TMP levels in fish were generally an order of magnitude higher than levels of triclopyr and TCP, particularly in the visceral portion of the animals. No adverse effects on water quality or on the non‐target biotic community were found following triclopyr applications. Results of these studies were comparable to those of triclopyr dissipation studies conducted in reservoirs, lakes and riverine systems in Georgia, Florida, Minnesota and Washington, indicating that the degradation and dissipation of triclopyr and its metabolites are similar in representative systems throughout the USA.

© 2001 Society of Chemical Industry
Synthesis and fungicidal activity of a series of novel aryloxylepidines
Authors: Kirby Neil V , Daeuble John F , Davis L Navelle , Hannum Anna C , Hellwig Karin , Lawler Lori K , Parker Marshall H , Pieczko Mary E
Published: August 2002

A series of novel (hetero)aryloxylepidine derivatives was devised as hybrid structures of the phenoxyquinoline and phenethoxyquin(az)oline fungicides. Synthesis of these targets required the development of several new routes to derivatised 4‐hydroxymethylquinolines, and subsequent coupling with phenols or haloarenes. The aryloxylepidines generally showed moderate broad‐spectrum fungicidal activity across several diseases of cereals. Substitution of the quinoline ring with chlorine at the 7‐ and/or 5‐positions gave molecules with high levels of protectant activity against Erysiphe graminis f sp tritici (powdery mildew of wheat), but this did not improve the level of fungicidal activity against other diseases. In vitro activity against mitochondrial electron transport complex I (MET) derived from Ustilago maydis showed that 8‐fluorolepidine analogues were moderately active at this target site, while the more fungicidally active 7‐ and 5,7‐substituted compounds were inactive. This indicates that MET is not the primary target of these highly active powdery mildewicides.

© 2001 Society of Chemical Industry
Photolysis of fluchloralin in aqueous methanol
Authors: Saha Tapas , Bhattacharyya Anjan
Published: August 2002

The photodegradation of fluchloralin by UV irradiation or sunlight in aqueous methanolic solution has been examined. In the presence of titanium dioxide five photoproducts were obtained, but only four in its absence. One photoproduct, 2, 2′‐azoxy‐bis(α,α,α‐trifluoro‐6‐nitro‐p‐toluidine) is reported for the first time as a metabolite of fluchloralin. In natural sunlight the rate of degradation was higher than in UV light and titanium dioxide had almost no effect on the rate of degradation.

© 2001 Society of Chemical Industry
Cu(OBt)2 and Cu(OAt)2, copper(II)‐based racemization suppressors ready for use in fully automated solid‐phase peptide synthesis
Authors: Van Den Nest Wim , Yuval Shov , Albericio Fernando
Published: August 2002

The complexes Cu(OBt)2 and Cu(OAt)2, which are derived from copper(II) and HOBt and HOAt, respectively, are shown to be more effective in suppressing racemization during solid‐phase peptide synthesis (SPPS) than are those compounds currently being used for this purpose. These compounds can readily be used in conjunction with the commonly applied coupling reagents in fully automated systems for solid‐phase peptide chemistry. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd.
Ambient oxygen ingress rate method—an alternative method to Ox‐Tran for measuring oxygen transmission rate of whole packages
Authors: Larsen Hanne , Kohler Achim , Magnus Ellen Merethe
Published: August 2002

The ambient oxygen ingress rate method (AOIR) is an alternative method to Ox‐Tran for measuring the oxygen transmission rates (OTR) of whole packages. The objective of the present work was (a) to compare OTR values obtained by the two methods, and (b) to evaluate the use of the AOIR method for measuring OTR at realistic food storage temperatures and humidity levels. The AOIR method gave equal OTR values compared to the Ox‐Tran method for the five different types of whole packages used in the experiment, with OTR values in the range 0.06–1.48 ml O2/day. The repeatability of the AOIR method measured on an HDPE bottle was ±2.6% of the measured value in this experiment. This is slightly higher than the general specifications of the Ox‐Tran method (1% of reading for packages). However, the AOIR method can be considered to be a reliable, precise and cheap alternative method to the Ox‐Tran method for measuring OTR of whole packages. The capacity of the method is also high. The AOIR method showed satisfactory results when comparing OTR for packages tested under realistic food storage conditions covering 23°C/50% relative humidity (RH) and at 4°C/60% RH on the outside, combined with water (100% RH) or dry air inside the packages. Copyright © 2000 John Wiley & Sons, Ltd.
Process capability analysis in the presence of autocorrelation
Authors: Noorossana R.
Published: August 2002

Process capability analysis when observations are autocorrelated is addressed using time series modelling and regression analysis. Through the use of a numerical example, it is shown that the variance estimate obtained from the original data is no longer an appropriate estimate to be considered for conducting process capability analyses. Copyright © 2002 John Wiley & Sons, Ltd.
Simple method for the precise calculation of atomic energy levels of IB elements in the periodic table
Authors: Zheng Nengwu , Wang Tao , Ma Dongxia , Zhou Tao
Published: August 2002

Due to the complicated and typical electronic structure of atoms and ions of the IB group in the periodic table, theoretical calculation of their atomic energy levels has important theoretical and practical significance. In this article, the theoretical calculation of atomic energy levels of the atoms of IB group in the periodic table was completed for the first time within the scheme of the weakest bound electron potential model theory. The results were compared with experimental values and the deviations are about 0.1–1 cm−1. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Categorization of visualization tools in aspects of chemical research and education
Authors: Burewicz Andrzej , Miranowicz Nikodem
Published: August 2002

Chemistry is an experimental science whose research subjects are often not directly available within the close dimensions of a time or space. To optimize a particular teaching process or research, it is necessary to visualize phenomena, processes, or objects. Consequently, visualization is significant to problem solving in research and teaching. Visualization is applicable in those situations when it is required to reduce the dimensions of experimental objects to given numbers and values accessible to direct experience. In educational practice, this is related to one of the following situations: (1) the experiment is too long or too short; (2) the dimensions of the examined object are too small or too large; (3) the environment of the experiment is not accessible; (4) the parameters of the experiment or its effects are not directly available to the observer's senses; (5) there is a need for multiple revisions of the experiment; (6) the experiment is difficult to arrange or revise effectively; (7) the experiment is dangerous; (8) the experiment is too expensive; etc. The presentation of models of physicochemical processes and phenomena, models of atoms and molecules, and mechanisms of reaction, as well as experimental data and their mathematical models, provides a basis for considering the formulation of correct conclusions. The appropriate choice of visualization algorithms is decisive of the effectiveness of theoretical analyses. The main aspect of visualization is obviously its application to teaching or research. Thus, the choice of techniques depends on whether it is used for recognition, explanation, memorization, inspiration, or motivation. In research, the importance as well as area of usefulness of three main categories of visualization have also been established. These categories are: illustration—relating to the presentation of an existing picture of object; representation—the presentation of an image assigned to an object; and visualization—related to the presentation of an image created for the object. Research work on preparing means for visualization confirms that, depending on the particular aspect of categorizing visualization, it may be useful, as well, to assign additional criteria such as dimensions, degree, functions, methodological contexts, experimental relationship, and medial effectiveness into visualization. In recent years, at the Institute of Chemical Education of Poznan's Adam Mickiewicz University such research was undertaken. Its main aim was to determine the educational effectiveness of different types of chemical visualizations. Methods for the visualization of chemical issues were developed and a series of original video and animation sequences presenting different aspects of chemical visualization prepared. Interactive Internet instructions sets were produced and methods of visualization categorized. Effectiveness in using different types of chemical visualizations was estimated. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Deduction of the Klein–Fock–Gordon equation from a non‐Markovian stochastic equation for real pure‐jump process
Authors: Skorobogatov G. A.
Published: August 2002

From the Madelung's work in 1926, it became clear that the pair of adjoint Schrödinger equations is equivalent to two equations of hydrodynamic representation for probability density and mean momentum Both these equations can be derived from the quantum transport equation (QTE) for a probability density P(, , t) as two equations for the two first moments Then, QTE can be obtained from a non‐Markovian stochastic Kolmogorov–Gikhman–Skorokhod equation for a real pure‐jump process. Similarly, the Klein–Fock–Gordon equation follows from non‐Markovian relativistic QTE (RQTE). Thus, all quantum mechanics as mathematical theory is a topic of the theory of real pure‐jump non‐Markovian stochastic processes. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
A note on nodal structures, partial screening, and periodic trends among alkali metals and alkaline earths
Authors: Pyykkö Pekka
Published: August 2002

The first ionization potential of Na is close to that of Li but much larger than that of K. Similar trends were noted for the electronegativities or for the calculated atomic charges in partially covalent alkali metal hydrides MH or methide compounds, MCH3 (M=Li–Cs) by Lambert, Kaupp, and Schleyer. This trend can be understood by combining the effects of the nodal structure, as function of the principal quantum number, n, and the lanthanide contraction‐like effects of partial screening from both the 1s and 2p shells. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Symplectic molecular dynamics integration using normal mode analysis
Authors: Janežič Dušanka , Praprotnik Matej
Published: August 2002

The split integration symplectic method (SISM) for molecular dynamics (MD) integration using normal mode analysis based on a factorization of the Liouville propagator is presented. This approach is quite distinct from others that use fractional‐step methods, owing to the analytical treatment of high‐frequency motions. The method involves splitting the total Hamiltonian of the system into a harmonic part and the remaining part. Then the Hamilton equations are solved using a second‐order generalized leapfrog integration scheme in which the purely harmonic Hamiltonian (which represents the main contribution of the chemical bonds and angles) is treated analytically, i.e., independent of the step size of integration, by a normal mode analysis that is carried out only once, at the beginning of calculation. The whole integration step combines analytical evolution of the harmonic part of the Hamiltonian with a correction arising from the remaining part. The proposed algorithm requires only one force evaluation per integration step. The algorithm was tested on a simple system of linear chain molecules. Results demonstrate the method makes possible the integration of the MD equations over larger time steps without loss of stability while being economical in computer time. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 84: 2–12, 2001
Semiempirical and spectroscopic study of a novel porphyrin dyad
Authors: Janvier P. , Le Questel J.‐Y. , Illien B. , Suresh S. , Blart E. , Quintard J.‐P. , Odobel F.
Published: August 2002

Semiempirical calculations and ultraviolet–visible experiments have been carried out on a novel bisporphyrin system. The present work reveals that an oligothiophene ethynyl‐linked spacer promotes high electronic interactions over a large distance in this dyad. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 84: 259–263, 2001
Theoretical study of the vertical electron excitation of linear carbon clusters C3, C5, and C7
Authors: Giuffreda M. G. , Deleuze M. S. , François J.‐P. , Trofimov A. B.
Published: August 2002

The vertical electron excitation spectra of linear carbon clusters C3, C5, and C7 have been investigated by means of polarization propagator calculations using the second‐order algebraic diagrammatic construction [ADC(2)] scheme. The structure of singlet and triplet excited‐state manifolds below the lowest ionization threshold has been analyzed in detail for the smallest prototype cluster C3. The electronic spectra of all three molecules contain numerous low‐lying single and double valence excitations, reflecting strongly the correlated nature in these clusters. The density of the excited states becomes increasingly high above the onset of Rydberg excitations. A substantial mixing of various valence and Rydberg configurations in this region does not allow for simple interpretation of the final electronic states. The spectroscopic and photophysical implications of this complex situation are discussed. Where possible the computed excitation energies and oscillator strength are compared with available experimental and previous theoretical data. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Structural determination of lysophosphatidylcholines extracted from marine sponges by fast atom bombardment tandem mass spectrometry
Authors: Hong Jongki , Cho Kun , Kim Young Hwan , Cheong Chaejoon , Lee Kwang‐Sik , Jung Jee H.
Published: August 2002

A series of lysophosphatidylcholines were isolated from the marine sponge Spirastrella abata by reversed‐phase high performance liquid chromatography (HPLC) and analyzed by fast atom bombardment mass spectrometry (FAB‐MS). Their structural elucidation was carried out with fast atom bombardment tandem mass spectrometry (FAB‐MS/MS). The collision‐induced dissociation (CID) of protonated and sodiated molecular ions produced diverse product ions via a series of dissociative processes. Because of the positive charge of the amine group at the end of the molecules, charge‐remote fragmentation patterns of specific ions, [M + H]+ or [M + Na]+, were very helpful for the identification of product ions which are characteristic for choline and long hydrocarbon chains substituted at the glycerol back bone. Moreover, the CID‐MS/MS spectra of sodium adducted molecular ions for lysophosphatidylcholines yielded common characteristic fragment ions for the choline moiety and characteristic ions [M + Na‐103]+, [M + Na‐85]+ and [M + Na‐59]+ in the higher mass region. Copyright © 2001 John Wiley & Sons, Ltd.
Two‐photon ionization thresholds of matrix‐assisted laser desorption/ionization matrix clusters
Authors: Lin Qiong , Knochenmuss Richard
Published: August 2002

Direct two‐photon ionization of the matrix has been considered a likely primary ionization mechanism in matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry. This mechanism requires that the vertical ionization threshold of matrix materials be below twice the laser photon energy. Because dimers and larger aggregates may be numerous in the early stages of the MALDI plume expansion, their ionization thresholds are important as well. We have used two‐color two‐photon ionization to determine the ionization thresholds of jet cooled clusters of an important matrix, 2,5‐dihydroxy benzoic acid (DHB), and mixed clusters with the thermal decomposition product of DHB, hydroquinone. The thresholds of the clusters were reduced by only a few tenths of an eV compared to the monomers, to an apparent limit of 7.82 eV for pure DHB clusters. None of the investigated clusters can be directly ionized by two nitrogen laser photons (7.36 eV), and the ionization efficiency at the thresholds is low. Copyright © 2001 John Wiley & Sons, Ltd.
Loss of charged versus neutral heme from gaseous holomyoglobin ions
Authors: Chrisman Paul A. , Newton Kelly A. , Reid Gavin E. , Wells J. Mitchell , McLuckey Scott A.
Published: August 2002

The dissociation of holomyoglobin ions ranging in charge state from +10 to +2 has been studied using collisional activation in a quadrupole ion trap. Collisional activation times and amplitudes were varied to investigate the effects of these variables on dissociation of the heme group from the holoprotein. The onset of neutral heme loss occurs at a lower activation amplitude than loss of charged heme. For solutions of ferri‐myoglobin, charged heme loss was prominent for +10 to +4 holomyoglobin ions, while neutral heme loss product was found to be dominant for charge states +3 and +2. For any given charge state, activation of holomyoglobin ions from a solution containing primarily ferro‐myoglobin yielded significantly more abundant neutral heme loss products than was observed for activation of ions from solutions containing primarily ferri‐myoglobin. The relative concentrations of the two oxidation states were shown to be affected by redox chemistry within the nano‐electrospray emitter used in this work. Results from a double activation experiment revealed that the precursor ions of a given charge state contained a mixture of two populations, with ferro‐myoglobin giving rise to neutral heme loss upon dissociation and ferri‐myoglobin yielding charged heme. No evidence for electron transfer upon collisional activation of ferri‐myoglobin ions was observed. Furthermore, little or no evidence for electron transfer associated with ion/ion reactions with anions derived from perfluoro‐1,3‐dimethylcyclohexane was observed. Definitive results could not be drawn for the lowest precursor ion charge states (+3 and +2) due to low dissociation efficiencies. Copyright © 2001 John Wiley & Sons, Ltd.
Two‐dimensional separations with electrospray ionization ambient pressure high‐resolution ion mobility spectrometry/quadrupole mass spectrometry
Authors: Matz Laura M. , Asbury G. Reid , Hill Herbert H.
Published: August 2002

The coupling of ion mobility spectrometry (IMS) instruments with mass spectrometers has been described since early in IMS development, most commonly with quadrupole mass analyzers. The recent development of IMS with time‐of‐flight (TOF) instruments has demonstrated that the time compatibility (IMS milliseconds and TOFMS microseconds) of the two techniques enables rapid two‐dimensional separations to be performed, theoretically in the order of seconds for a complete analysis. This study presents a unique way to operate a traditional IMS/QMS system to attain separations similar to those achieved with IMS/TOF. For this new approach, the quadrupole was slowly scanned in the single‐ion monitoring mode while IMS spectra were continually embedded in each m/z step. In this way, two‐dimensional separations (IMS drift times and m/z) were obtained using the traditional IMS/QMS arrangement. An example of a five amino acid separation (quadrupole scan of 40 m/z values at a rate of ∼7 steps/min) led to a complete two‐dimensional analysis within 6 min, comparable to rapid chromatographic separations with mass spectrometry. Proposed approaches to reduce the analysis time are discussed and a reduction in the analysis time to less than 1 min is feasible when the IMS/QMS separation conditions are optimized. Copyright © 2002 John Wiley & Sons, Ltd.
Time‐of‐flight studies of secondary ions produced by 400 eV He+ ion impact on Ar, Kr, and Xe thin films at 8 K
Authors: Hiraoka Kenzo , Watanabe Makoto , Eguchi Daisuke , Okazaki Shigemitsu , Sato Tetsuya
Published: August 2002

Secondary ions produced by 400 eV He+ ion impact on Ar, Kr, and Xe thin films deposited on a silicon substrate at 8 K were measured as a function of film thickness using a time‐of‐flight secondary‐ion mass spectrometer. For Ar, the cluster ions Arn+ up to n = 4 as well as the monomer ion (n = 1) were observed and they showed characteristic film‐thickness dependence with increase of the film thickness up to ∼200 monolayers. This is due to the momentum transfer in the elastic collision between the incident He+ ion and the matrix Ar atoms and also to the relaxation of electronic excitations (e.g., holes and excitons) to phonons resulting in the film erosion. In contrast, neither dimer nor cluster ions were detected for solid Kr and Xe films. This is due to the less efficient momentum transfer in the elastic collision between He+ and Rg's (Rg = Kr and Xe) and also to the efficient electronic energy migration in solid Kr and Xe. The ions originating from the silicon substrate such as Si+, SiCH3+, SiOH+, and C+ were found to be sensitized by the deposition of Xe film in the range of 0–40 monolayers. The penetration depths of the primary ion He+ through the rare gas films increase in the order Ar < Kr < Xe. Copyright © 2002 John Wiley & Sons, Ltd.
Considerations for design of a Fourier transform mass spectrometer in the 4.2 K cold bore of a superconducting magnet
Authors: O'Connor Peter B.
Published: August 2002

An external source Fourier transform mass spectrometer (FTMS) constructed inside the vertical cold bore of a superconducting magnet will have dramatic advantages in effective magnetic field, noise figures, and base pressure over current commercially available external source FTMS systems. There are substantial, but solvable, difficulties in the design, primarily with regard to control of the helium boiloff rate to an acceptable level, as well as relatively minor design challenges with heat sinks, contraction of metallic ion optic elements in the extreme temperature, and tandem mass spectrometry experiments. However, the ability to construct the FTMS inside the narrow bore tube of existing, commercially available vertical bore NMR magnets will allow access to the upper magnetic field limit currently used by 900 MHz (21 Tesla) – 1 GHz (23.3 Tesla) NMR experiments. The vacuum system, simply by being held inside the cold bore at 4.2 K, will cryopump itself dropping base pressures substantially, and heat sinking the input resistor of the preamplifier to this cryogenically cooled vacuum chamber will allow reduction of the input Johnson noise by a factor of 8.4 with associated 8.4‐fold improvement in signal/noise, sensitivity, and dynamic range. The simultaneous improvement of three fundamental limiting factors in the FTMS (field strength, base pressure, and Johnson noise figure) will clearly outweigh the concomitant increased helium boiloff rate particularly if this rate can be dropped to the estimated <5 L/day range. The additional use of modern cryorefrigerators will further reduce helium boiloff to zero except during MSn experiments and system cooldown. Copyright © 2002 John Wiley & Sons, Ltd.
Nordic consumers and the challenge for sustainable housing
Authors: Svane Örjan
Published: August 2002

In the Nordic countries, housing is one of society's greatest users of resources. Making housing more sustainable will call for changes in buildings, management routines and residents' habits, each having its possibilities as well as a built in resistance against change. Households might play a key role in this change, directly as consumers, but also indirectly and jointly as pressure groups towards real estate owners, managers and local society. Making housing more sustainable can be seen as society's ‘sustainability challenge’ to the housing consumers. In this paper, the extent of this challenge is discussed for the households of the Nordic countries, for different types of ownership and building etc. Its realization is seen in a ten‐year perspective and in relation to the acquisition, maintenance, operation and use of the dwellings. Preliminary results indicate that a move to a new dwelling will give the household an opportunity to influence many aspects of its environmental impacts, but that moving will have little direct effect on the environmental performance of the built environment as a whole. Furthermore, that the activities of daily living have a potential for improvement without the inertia of reconstructing the building stock. In the end, however, co‐operation between households and other stakeholders of the building sector is often a prerequisite for change. Copyright © 2002 John Wiley & Sons, Ltd. and ERP Environment.
Characterization of finishing on polyamide fibres
Authors: Biganska Olga , Darque‐Ceretti Evelyne , Giulieri Françoise , Combarieu Robert
Published: August 2002

For a fundamental approach to fibres for composite applications, it is essential to develop efficient methods to analyse the composition and distribution of the sizing layer on the fibres. The aim of this investigation is to propose a combination of methods for surface characterization of manufactured finished fibres. The task is not straightforward because the composition of finishing is usually kept secret. Polyamide fibres with two different types of finishing are investigated by mean of several methods: optical microscopy and scanning electron microscopy (SEM), x‐ray photoelectron spectroscopy (XPS), time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) and Langmuir balance for monolayer study. Classical methods of observation and analysis (microscopy, XPS and ToF‐SIMS) applied directly to the fibres do not show any difference in the two types of finishing. Only the Langmuir balance demonstrates the difference between two types of fibres finishing. At the water contact, only one of the two types of fibres loses a compressible monolayer of insoluble substance on the water surface. This layer then is characterized by ToF‐SIMS. An attempt to describe the finishing composition is made. Copyright © 2001 John Wiley & Sons, Ltd.
Influence of interfacial depth on depth resolution during GDOES depth profiling analysis of thin alumina films
Authors: Shimizu K. , Habazaki H. , Skeldon P. , Thompson G. E. , Marcus R. K.
Published: August 2002

Factors controlling the depth resolution in radio frequency glow discharge optical emission spectroscopy (rf‐GDOES) depth profiling analysis of thin films have been investigated using anodic alumina films of varying thicknesses with delta function marker layers of ∼2 nm width located at various depths from the oxide surface. In rf‐GDOES depth profiling analysis, where a relatively large area of ∼4 mm in diameter is analysed, it was found that the depth resolution is determined mainly by the large‐scale variation of sputtering rate across the crater. Despite the relatively large area analysed, the uniformity of sputtering rate across the crater was constant to within 1% under the optimum Ar pressure except for near‐edge regions of ∼0.4 mm width, where the sputtering rate was ∼6% higher than in the central crater region. Owing to this relatively minor non‐uniformity of sputtering rate, the depth resolution degrades approximately linearly with depth. A depth resolution of ∼1.3 nm was realized to depths of ∼25 nm, where the degradation of depth resolution due to the non‐uniformity in sputtering rate is insignificant. The depth resolution is close to the ultimate depth resolution in sputter depth profiling, claimed to be 0.7– 1.0 nm, and arises from the minimal atomic mixing associated with film sputtering with Ar+ions of very low energy, ∼50 eV, in rf‐GDOES analysis. Copyright © 2001 John Wiley & Sons, Ltd.
Analysis of the infection system of human T‐cell leukaemia virus type I based on a mathematical epidemic model
Authors: Eshima Nobuoki , Tabata Minoru , Kikuchi Hiroshi , Karukaya Shigeru , Taguchi Toshio
Published: August 2002

Human T‐cell leukaemia virus type I (HTLV‐I) is a retrovirus that causes adult T‐cell leukaemia (ATL). HTLV‐I has existed in Japanese people for thousands of years. In order to prevent an epidemic of HTLV‐I, it is important to explain the infection system by a mathematical approach. By considering the main infection routes in Japan, that is: (i) mother‐to‐child transmission; (ii) male (husband)‐to‐female (wife) transmission; and (iii) female (wife)‐to‐male (husband) transmission, a mathematical model for describing the time‐dependent change of the infection proportion can be constructed. An upper bound of the present infection rate per year in male‐to‐female transmission and that in female‐to‐male transmission is given by the model, and theoretical results related to HTLV‐I infection are also deduced from the mathematical model. A simulation study based on the present model demonstrates the theoretical results relating to the HTLV‐I infection. Copyright © 2001 John Wiley & Sons, Ltd.
Correcting for measurement error in binary and continuous variables using replicates
Authors: White Ian , Frost Chris , Tokunaga Shoji
Published: August 2002

Measurement error in exposures and confounders leads to bias in regression coefficients. It is possible to adjust for this bias if true values or independent replicates are observed on a subsample. We extend a method suitable for quantitative variables to the situation where both binary and quantitative variables are present. Binary variables with independent replicates introduce two extra problems: (i) the error is correlated with the true value, and (ii) the measurement error probabilities are unidentified if only two replicates are available. We show that – under plausible assumptions – adjustment for error in binary confounders does not need to address these problems. The regression coefficient for a binary exposure is overadjusted if methods for continuous variables are used. Correct adjustment is possible either if three replicates are available, or if further assumptions can be made; otherwise, bounds can be put on the correctly adjusted value, and these bounds are reasonably close together if the exposure has prevalence near 0.5. Copyright © 2001 John Wiley & Sons, Ltd.
Implementing software process improvement: an empirical study
Authors: Hall Tracy , Rainer Austen , Baddoo Nathan
Published: August 2002

In this paper we present survey data characterizing the implementation of SPI in 85 UK companies. We aim to provide SPI managers with more understanding of the critical success factors of implementing SPI. We present an analysis of the critical implementation factors identified in published case studies. We use a questionnaire to measure the use of these factors in ‘typical’ software companies. We found that many companies use SPI but the effectiveness of SPI implementation is variable. Many companies inadequately resource SPI and fail to evaluate the impact of SPI. On the other hand, companies show a good appreciation of the human factors associated with implementing SPI. Copyright © 2002 John Wiley & Sons, Ltd.