bluuebunny/crossref_metadata_2025 huggingface dataset:
Construction of a permeable reactive barrier in a residential neighborhood
Authors: Richards Peter
Published: October 2002

In June 2001, the Massachusetts Department of Environmental Protection (DEP) installed a permeable
reactive barrier (PRB) within a roadway in Needham, Massachusetts, to treat a plume of chlorinated
solvents migrating toward two public water‐supply wells located in the adjacent town of Wellesley,
Massachusetts. The solvents originated from an electronics manufacturer located approximately 2,300 feet upgradient
of the roadway and 5,200 feet upgradient of the public supply wells. Chlorinated solvents, primarily trichloroethene
(TCE), had migrated past the roadway to within 300 feet of the public supply wells. Two contaminant
transport models prepared by the DEP's design contractor and the EPA indicated that the plume would reach the
well field if no response actions were taken. To mitigate the future impact to the municipal well field, the DEP
decided to install a PRB composed of zero‐valent granular iron across the path of the plume along Central
Avenue in Needham. Though several dozen PRBs have been installed at sites worldwide and the technology is no longer
considered innovative, the application of the technology in a roadway that receives 17,000 vehicles per day within a
residential neighborhood is unique and presented difficulties not typically associated with PRB installations. The
Needham PRB was also one of the first zero‐valent iron PRBs installed using the slurry trench method to treat
chlorinated compounds. © 2002 Wiley Periodicals, Inc.
Biofiltration of airstreams contaminated with MTBE
Authors: Singh Harvinder , Sanders Dee Ann , Veenstra John N.
Published: October 2002

The treatment of groundwater contaminated with low concentrations of methyl tertiary butyl ether
(MTBE) is of nationwide concern. Many treatment techniques include removing MTBE vapors from
groundwater, resulting in airstreams that require treatment. One method used for air‐phase MTBE
treatment is biofiltration. In a biofilter, the vapors pass through a reactor that contains
MTBE‐biodegrading organisms attached to a porous media. This article reports the results of a
biofiltration study to treat air contaminated with MTBE at concentrations of 0.2 to 0.33 mg/l,
concentrations frequently encountered in the field. The results indicate that MTBE removal at these low
concentrations is not as efficient as removals seen at higher concentrations. Activated carbon was shown to be
a superior biofiltration medium, compared with media that do not adsorb MTBE vapors. Activated carbon was
especially helpful in treatment shock loads of MTBE. © 2002 Wiley Periodicals, Inc.
Vibration and stability control of robotic manipulator systems consisting of a thin‐walled beam and a spinning tip rotor
Authors: Song Ohseop , Librescu Liviu , Kwon Hyuck‐Dong
Published: October 2002

Vibration and stability feedback control of a robotic manipulator modeled as a cantilevered

thin‐walled beam carrying a spinning rotor at its tip is investigated. The control is achieved via

incorporation of adaptive capabilities that are provided by a system of piezoactuators, bonded or embedded into

the host structure. Based on converse piezoelectric effect, the piezoactuators produce a localized strain field

in response to an applied voltage, and as a result, an adaptive change of vibrational and stability response

characteristics is obtained. A feedback control law relating the piezoelectrically induced bending moments at

the beam tip with the appropriately selected kinematical response quantities is used, and the beneficial effects

of this control methodology upon the closed‐loop eigenvibration characteristics and stability boundaries

are highlighted. The cantilevered structure modeled as a thin‐walled beam, and built from a composite

material, encompasses non‐classical features, such as anisotropy, transverse shear, and secondary

warping, and in this context, a special ply‐angle configuration inducing a structural coupling between

flapping‐lagging and transverse shear is implemented. It is also shown that the directionality property

of the material of the host structure used in conjunction with piezoelectric strain actuation capability, yields

a dramatic enhancement of both the vibrational and stability behavior of the considered structural system.

© 2002 Wiley Periodicals, Inc.
Adsorption of polysulphide sealants onto organosilane‐coated aluminium and aluminium substrates
Authors: Rattana Acharawan , Abel Marie‐Laure , Church Simon , Watts John F.
Published: October 2002

Study of the adsorption of polysulphide sealants with oxidized aluminium and oxidized aluminium treated with an organosilane adhesion promoter, γ‐glycidoxypropyltrimethoxysilane (GPS), was achieved using XPS and time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). The kinetics and thermodynamics of adsorption have been investigated. The kinetics of adsorption were investigated to establish an exposure equilibrium time for the adsorption of polysulphide sealants onto both surfaces. Specimens were treated with polysulphide sealant solutions in toluene and different treatment times ranging from 30 s to 30 min. It was found that a 20 min treatment time allows the adsorption equilibrium of polysulphide sealants on both substrates to be reached. The thermodynamics of adsorption were studied as follows: all substrates have been treated with solutions of polysulphide sealants in toluene in a range of seven concentrations. Thermodynamic studies were carried out by the construction of adsorption isotherms. It was found that the polysulphide sealants adsorbed more on GPS‐treated surfaces; on both surfaces, competition was observed between components present in the sealant formulation. The high‐resolution C 1s XPS spectra were also peak fitted to account for the functional groups known to be present in the sealants and identified from ToF‐SIMS data. Copyright © 2002 John Wiley & Sons, Ltd.
Role of salts on BSA adsorption on stainless steel in aqueous solutions. I. FT‐IRRAS and XPS characterization
Authors: Pradier C. M. , Costa D. , Rubio C. , Compère C. , Marcus P.
Published: October 2002

The understanding of protein interaction with metal surfaces has become a key question for the use of materials in medicine, in the food industry or in marine environment in connection with the process of biofouling. However, the role of the various salts present in natural seawater has never been systematically investigated. In the present work, we studied the adsorption of a protein, bovine serum albumin (BSA), on stainless‐steel surfaces in artificial seawater and in aqueous solutions containing NaCl, NaCl + CaCl2 and NaCl + MgCl2, the total concentration of salts being identical to that of the natural seawater (36 g l−1); the BSA concentration was fixed at 20 mg l−1. After rinsing and drying, the surface was analysed by Fourier transform infrared reflection–adsorption spectroscopy (FT‐IRRAS) and x‐ray photoelectron spectroscopy (XPS). After immersion in aqueous solutions containing NaCl or NaCl + CaCl2 and rinsing in saline solutions, the amount of adsorbed BSA is small. It increases by almost one order of magnitude if the immersion is performed in NaCl + MgCl2 aqueous solution; after 24 h of immersion it reaches a saturation value very close to that attained in natural seawater. At saturation of the stainless‐steel surface by the protein, the XPS metal signals were still detected, suggesting that the protein layer is heterogeneous, leaving patches of the surface almost uncovered. The amount of adsorbed BSA is reduced by almost one order of magnitude when the samples are rinsed in pure, demineralized water due to the dissolution of Mg2+ cations and the elimination of loosely adsorbed proteins. The presence of Mg2+ cations within the BSA layer is confirmed by angle‐resolved XPS analyses. Copyright © 2002 John Wiley & Sons, Ltd.
XPS study of oxides formed on nickel‐base alloys in high‐temperature and high‐pressure water
Authors: Machet A. , Galtayries A. , Marcus P. , Combrade P. , Jolivet P. , Scott P.
Published: October 2002

The aim of this work is to characterize the oxidation behaviour of different nickel‐base alloys exposed to high‐temperature and high‐pressure water for short oxidation times. The behaviour of Alloy 600 (74% Ni, 16% Cr, 9% Fe), Alloy 690 (60% Ni, 30% Cr, 9% Fe) and Alloy 800 (47% Fe, 32% Ni, 21% Cr) exposed to simulated, pressurised water reactor primary water at 325°C has been compared. From the combination of chemical and structural data obtained by XPS, nuclear reaction analysis and scanning electron microscopy, the chemical composition and the morphology of the oxide formed on the surfaces have been determined. All alloys present a duplex oxide layer composed of Fe‐rich crystals in the external layer and an inner Cr‐rich layer that is compact and continuous. The oxide thicknesses were 4–20 nm for Alloy 600 exposed for 0–400 h, 4–40 nm for Alloy 690 exposed for 0–400 h and 4–150 nm for Alloy 800 exposed for 0 to 150 h. The kinetics of oxidation of these samples most probably fit a logarithmic growth equation. Copyright © 2002 John Wiley & Sons, Ltd.
Study of KTiOPO4 surface by x‐ray photoelectron spectroscopy and reflection high‐energy electron diffraction
Authors: Atuchin V. V. , Kesler V. G. , Maklakova N. Yu. , Pokrovsky L. D. , Semenenko V. N.
Published: October 2002

Structural and electronic properties of the as‐grown (011) crystal face and the mechanically polished (001) surface of potassium titanyl phosphate (KTiOPO4 or KTP) have been investigated by core‐level x‐ray photoelectron spectroscopy and reflection high‐energy electron diffraction (RHEED). With XPS analysis the original element binding energies, Auger parameters for K 2p3/2 and P 2p core levels, relative element contents and valence band structure have been determined for both crystal cuts. A great depletion of O, K and P in the (011) face with respect to the (001) surface was discovered on comparison of element peak areas. The Ti 2p3/2 peak areas were virtually the same for both cuts investigated. The relative element contents at the (001) surface were very close to the formal composition of KTiOPO4, so it is optimal to use the polished (001) KTP surface cleaned by ion bombardment and the Ti 2p3/2 core level as standards for determination of the chemical composition of doped crystal surfaces. Copyright © 2002 John Wiley & Sons, Ltd.
Effect of sulphur on the formation of graphite at the surface of carburized iron
Authors: Moszyński D. , Grabke H. J. , Schneider A.
Published: October 2002

The effect of sulphur on the formation of graphite at the surface of carburized iron and the decomposition of cementite were studied by Auger electron spectroscopy (AES). Graphite growth was observed on the iron surface covered with various amounts of sulphur. On the surface with a sulphur coverage of ∼40% a graphite layer was already formed at 400°C. Sulphur islands present on the surface were not influenced by the growing graphite. If the iron surface was saturated with sulphur, graphite growth started only at temperatures of >550°C. In this case, a graphite layer was formed on top of the adsorbed sulphur atoms. The nucleation sites for graphite formation may be grain boundaries, phase boundaries and other crystal defects or vacancies in the sulphur layer.

The decomposition of cementite on the sample surface was also studied following the increase of the graphite peak. Coverage of the surface with sulphur led to a substantial decrease of the decomposition rate of cementite. A linear decrease of the rate of cementite decomposition with increasing sulphur concentration on the surface was found. When the cementite surface was saturated with sulphur, the formation of graphite was almost stopped, but even then a slow graphite growth could be observed. Copyright © 2002 John Wiley & Sons, Ltd.
Sulphur segregation on free and oxidized NiAl(001)
Authors: Rivoaland L. , Maurice V. , Bacos M.‐P. , Marcus P.
Published: October 2002

Auger electron spectroscopy (AES), low‐energy electron diffraction (LEED) and X‐ray photoelectron spectroscopy (XPS) data on the segregation of sulphur at the surface of an NiAl(001) single crystal and at the interface with alumina thin films are reported. The results show that sulphur segregates at the free metallic surface. The amount of segregated sulphur decreases with increasing aluminium content of the surface. Although the segregation of aluminium is favoured thermodynamically, segregation kinetics and diffusion coefficients measured at 700, 750, 800 and 850°C [D = 0.15 exp(−2 18 000/RT)] show that the segregation of sulphur is favoured kinetically. Saturation of the metallic surface with an amorphous alumina layer formed at room temperature blocks the segregation of sulphur. However, in the initial stages of oxidation at 950°C where the transient θ alumina grows by cationic transport and injection of vacancies at the interface, sulphur segregates at the interface between the alumina thin films and the metallic substrate as measured by XPS. Copyright © 2002 John Wiley & Sons, Ltd.
Epitaxial growth of CaSi2 on Si(111)
Authors: Schöpke A. , Würz R. , Schmidt M.
Published: October 2002

Thin Ca films were evaporated on Si(111) under ultrahigh vacuum conditions and annealed in the temperature range 200–650°C. The interdiffusion of Ca and Si was examined by ex situ Auger depth profiling. In situ monitoring of the Si 2p core‐level shift by x‐ray photoelectron spectroscopy was employed to study the silicide formation process. The formation temperature of CaSi2 films on Si(111) was found to be ∼350°C. Epitaxial growth takes place at ≥400°C. The morphology of the films, observed by atomic force microscopy, was correlated with their crystallinity as analysed by x‐ray diffraction. Copyright © 2002 John Wiley & Sons, Ltd.
XPS study of fresh and oxidized (Pb,Ge)Te surfaces
Authors: Yashina L. V. , Kobeleva S. P. , Neudachina V. S. , Shatalova T. B. , Zlomanov V. P.
Published: October 2002

The oxidation of (Pb,Ge)Te crystal surfaces at ambient temperature and humidity was studied by means of XPS in a time range from minutes to months. Vacuum‐cleaved crystal was used for the experiment. It was found that Ge in a PbTe lattice occupies two different positions. At one of them, donor behaviour is revealed and the concentration of donor atoms increases at temperatures lower than those of the cubic–rhombohedral phase transition. It was found that oxidation takes place even after a few minutes of air exposure. Germanium atoms oxidize entirely to oxidation state +4, this being followed by slow oxidation of tellurium atoms from oxidation state −2 to +4. After a long air exposure, significant surface enrichment in Pb was observed. Copyright © 2002 John Wiley & Sons, Ltd.
Study of thin oxide films by ellipsometry and ARXPS
Authors: Tichopádek P. , Nebojsa A. , Čechal J. , Bábor P. , Jurkovič P. , Navrátil K. , Šikola T.
Published: October 2002

In the paper the application of a simple spectroscopic ellipsometer for ex situ and in situ studies on SiO2 films (including native oxides on Si) is reported. It is shown that the ellipsometer is a reliable tool for the monitoring of chemical etching of SiO2 films with thicknesses of >10 nm. When the films become thinner, the results are strongly influenced by the contamination and roughness of their surface layers. The concentration profiles of these ultrathin films (<10 nm) were analysed by angle‐resolved XPS. Further, the ability of the ellipsometer to monitor the removal of native oxides on an Si(111) surface by thermal flashing under ultrahigh vacuum conditions is demonstrated as well. Copyright © 2002 John Wiley & Sons, Ltd.
An electrochemical cell for study by XPS of lithium intercalation in oxide films
Authors: Castle J. E. , Guascito M. R. , Salvi A. M. , Decker F.
Published: October 2002

X‐ray photoelectron spectroscopy (XPS) is used to determine valence states of thin films. When used to elucidate the effects of electrochemical intercalation of ions in oxide films, the information required is the valence state of multivalence ions. To ensure that this information is not compromised by surface reoxidation, we have developed an in situ electrochemical cell for use with aprotic and anhydrous electrolytes. This cell has been used to study lithium intercalation in thin oxide layers built up on induim tin oxide (ITO)‐coated glass slides. Samples can be exposed for intercalation of lithium (or de‐intercalation), rinsed, dried and transferred within the vacuum of the spectrometer for characterization. The cell is designed to be withdrawn into a nacelle when not in use so as not to interfere with the normal use of the spectrometer. We have shown that the lithium electrode remains in good condition throughout storage periods. The successful use of the prototype cell gives an opportunity to develop the cell for related electrochemical studies in non‐aqueous electrolytes. Copyright © 2002 John Wiley & Sons, Ltd.
Rapid chemical and structural characterization of metastable thin‐film libraries by a combination of electron probe microanalysis and scanning x‐ray diffraction
Authors: Cremer R. , Richter S.
Published: October 2002

The increasing complexity of modern coatings leads to the demand for a cost‐effective tool for the development of new products in the advanced materials industry. One possible approach to this question is the adaptation of combinatorial methods to the specific requirements of the coatings industry.

In this paper, the deposition and characterization of two‐dimensionally laterally graded (Ti,Al,Si)N hard coatings deposited by a triple cathode magnetron sputtering arrangement is presented. The three cathodes, equipped with aluminium, silicon and titanium targets, respectively, were adjusted at a low angle to the surface. Additionally, a system of apertures was mounted between the cathodes. The relation between composition and structure of the resulting materials library was investigated by a combination of electron probe microanalysis (EPMA) and scanning x‐ray diffraction. Copyright © 2002 John Wiley & Sons, Ltd.
Coating of Ti–6Al–4V alloy substrates with Ti–N films by reactive d.c. sputtering
Authors: Sonoda T. , Watazu A. , Zhu J. , Shi W. , Kamiya A. , Kato K. , Asahina T.
Published: October 2002

The coating of Ti–6Al–4V alloy substrates with Ti–N films by reactive d.c. sputtering in an Ar–N2 gas mixture was examined to improve not only the blood compatibility but also the hardness and thereby the abrasion resistance of the alloy. The effects of discharge voltage on the formation of the Ti–N film were investigated. Under visual observation, the films deposited at various voltages appeared to be uniform and adhesive, whereas their colour tone varied with the voltage and the films obtained under a voltage of >400 V looked yellow‐gold. With SEM, the surface of the films deposited under various voltages were observed to consist of fine particles. According to AES, the Ti/N ratio in the depth direction was nearly constant in each of the films. On the basis of x‐ray diffraction, it was concluded that a Ti2N phase was formed predominantly in films deposited at 350 V whereas a TiN phase was formed predominantly in films deposited at a voltage of >400 V and the crystallinity of these phases was developed by heating the substrates to >400°C. Furthermore, it was found that the Vickers hardness Hv reached >2400 for films deposited at a voltage of >400 V onto the substrates and heated to >400°C. Therefore it was expected that the Ti–N films deposited onto the alloy substrates heated to >400°C under a voltage of >400 V could serve to improve not only the blood compatibility but also the hardness and thereby the abrasion resistance of the alloy. Copyright © 2002 John Wiley & Sons, Ltd.
STM and XRD studies of the adsorption and assembling structures of phthalocyanine and porphyrin
Authors: Lei S. B. , Wang J. , Dong Y. H. , Wang C. , Wan L. J. , Bai C. L.
Published: October 2002

Using scanning tunnelling microscopy (STM) and x‐ray diffraction (XRD), the assembling behaviour of substituted phthalocyanine and porphyrin on both hydrophobic and hydrophilic surfaces was investigated. Copper (II) 2,3,9,10,16,17,23,24‐octakis(octyloxy)‐29H,31H‐phthalocyanine (denoted as CuPcOC8) and 21,23‐dihydro‐5,10,15,20‐tetrakis[4‐(tetradecyloxy)phenyl]porphyrin (TTPP) molecules adsorb stably on a highly oriented pyrolytic graphite (HOPG) surface, yielding high‐resolution STM images. The results illustrate that alkyl molecular anchors can be used as a generalized approach for immobilization of organic molecules on hydrophobic surfaces. The XRD results show that on a hydrophilic substrate CuPcOC8 and TTPP form completely different assembled structures from those on a HOPG surface, which indicates that the polarity of the substrate has substantial effects on the assembling behaviour of organic molecules. Copyright © 2002 John Wiley & Sons, Ltd.
Preparation and characterization of Langmuir–Blodgett‐type arachidate films
Authors: Mohai M. , Kiss É. , Tóth A. , Szalma J. , Bertóti I.
Published: October 2002

Metal arachidate Langmuir–Blodgett (LB) films with Pb2+ and Cd2+ cations and varying numbers of monomolecular layers (2 and 4 monolayers, ML) were deposited on trimethylsilylated glass substrates. The arachidate salt formation was commenced during the film deposition from a water‐based solution. The extent of salt formation and the build‐up of the LB layer were evaluated by quantitative XPS.

The completeness of the salt formation was assessed by the atomic ratio of the carboxylic (‐COO‐)‐type carbon component with C 1s binding energy at ∼288.5 eV to that of the selected line of the actual cation.

The surface coverage of the glass substrate by the LB film was assessed by calculations based on a substrate–overlayer model using the XPS MultiQuant program. According to this model, the attenuation of the Si 2p photoelectron signal from the substrate by the 2 and 4 ML LB films (with 56 and 112 Å thickness, respectively) was calculated and compared with the measured intensities, enabling the completeness of the layer to be evaluated. The layer thickness values calculated from the measured intensity of the layer constituents reflected accurately the thickness derived from the geometry of the arachidate molecule, confirming both the adequacy of the model and the accuracy of the measurement.

In agreement with earlier results it was confirmed that salt‐based LB films are fairly stable under high vacuum conditions, although slow decomposition of lead arachidate films was detected during prolonged x‐ray irradiation. Copyright © 2002 John Wiley & Sons, Ltd.
Use and limitations of electron flood gun control of surface potential during XPS: two non‐homogeneous sample types
Authors: Baer D. R. , Engelhard M. H. , Gaspar D. J. , Lea A. S. , Windisch C. F.
Published: October 2002

The ability of charge compensation methods to control surface potential is examined for two types of non‐homogenous samples: a small conducting dot on an insulating substrate and an insulating thin film on a conductive substrate. Results demonstrate that two newer types of charge compensation systems have improved performance in relation to some previous flood gun systems, while reaffirming the concept that a primary objective of charge compensation is to find conditions for which the surface potential of the specimen is as uniform as possible. However, experiments involving both flood gun use and specimen grounding demonstrate that peak broadening and shifting can occur when two (or more) potentials are present in the region of analysis. Finally, the ability of interface charge to shift specimen potentials and measured binding energies demonstrates fundamental limitations to the absolute accuracy of binding energy measurements, but also remind us that charging phenomena can be used to obtain important information about the sample. Copyright © 2002 John Wiley & Sons, Ltd.
Investigation of sulphur diffusion at the CdS/CdTe interface of thin‐film solar cells
Authors: Gibson P. N. , Baker M. A. , Özsan M. E.
Published: October 2002

Diffusion of atoms across the CdS/CdTe interface during post‐deposition annealing is thought to have an important effect on the performance of CdS/CdTe‐based solar cells. Thin‐film solar cell samples were annealed at 400°C for three different times. The samples were etched sequentially in a bromine/methanol solution and then examined with Auger depth profiling and X‐ray diffraction. Profiling showed the as‐deposited samples to have little or no interfacial mixing, but annealing even for a short time caused diffusion of sulphur into the CdTe material. As the annealing times lengthened, the concentration of sulphur in the CdTe increased. X‐ray diffraction measurements indicated that the CdS layer rapidly crystallized into its hexagonal Greenockite modification, but with lattice parameters increased by 0.8%. This changed little with annealing time. The CdTe near the interface appeared to have a modified but well‐defined cubic structure with respect to reference CdTe, as indicated by splitting of the diffraction peaks, denoting the growth of a CdTexSy interfacial layer. This layer increased in thickness with annealing time and most probably has a stoichiometry within the range CdTeS0.04–CdTe0.88S0.12. Copyright © 2002 John Wiley & Sons, Ltd.
Pigment effects on ink–polymer bonding
Authors: West Robin H.
Published: October 2002

Pigment electrical properties are shown to influence the adhesion strength of ink bonding to ionomer polymer films exposed briefly to high relative humidity. Weakening of the ink/polymer interface is caused by the rapid formation of an interphase region that contains sodium ions and nitrate‐containing species. Replacing organic pigments with titanium dioxide inhibits the formation of the interphase region. A model based on electric field formation between counter‐ions and field attenuation from the pigment dielectric constant is proposed for the interphase formation. The model is tested using inks with mixed pigments and a direct correlation is found between nitrate enrichment in the interphase and relative electric field strength at the interface. Copyright © 2002 John Wiley & Sons, Ltd.
Replacing the no‐effect level (NOEL) with bounded effect levels (OBEL and LEBEL)
Authors: Hansson Sven Ove
Published: October 2002

From experiments or epidemiological studies designed to search for a particular toxic effect, it is in general possible to determine an upper bound for that effect. This observed bounded effect level (OBEL) is defined for both positive and negative experiments. It is non‐zero even for negative experiments, and it is inversely related to the size of the exposed group. The OBEL can be used to determine the linearly extrapolated bounded effect level (LEBEL) for various effect doses. Contrary to no‐observed‐effect' levels (NOELs), LEBEL values are designed to protect against type II (false negative) errors. It is proposed that LEBEL values replace NOELs as a tool for decision‐making. Copyright © 2002 John Wiley & Sons, Ltd.
Interval estimation of generalized odds ratio in data with repeated measurements
Authors: Lui Kung‐Jong
Published: October 2002

When the underlying responses are on an ordinal scale, the generalized odds ratio (GOR), defined as the ratio of the proportions of concordant and discordant pairs, is a useful index to summarize the difference between two stochastically ordered distributions of an ordinal categorical variable. We discuss interval estimation of the GOR for ordinal data with repeated measurements. On the basis of the Dirichlet‐multinomial model, we develop three asymptotic interval estimators of the GOR using Wald's test statistic, a logarithmic transformation, and a method analogous to Fieller's theorem, respectively. To evaluate and compare the finite‐sample performance of these estimators, we apply Monte Carlo simulation. We find that when the number of subjects per group is not large, the coverage probability of interval estimator using Wald's test statistic is likely to be less than the desired confidence level. By contrast, the coverage probability of the other two estimators are approximately equal to or larger than the desired confidence level. When the number of subjects per group is small and the intraclass correlation between repeated measurements within subjects is large, we note that applying the interval estimator derived from a method analogous to Fieller's theorem can lose efficiency. We also note that the interval estimator using the logarithmic transformation is generally preferable to the other two estimators with respect to both the coverage probability and the average length. Finally, on the basis of a few preliminary simulations, we do find some robustness for all the estimators developed here. We include an example comparing the inflammation grade after lung transplant between surgeries to illustrate the use of the proposed interval estimators. Copyright 2002 John Wiley & Sons, Ltd.
Clinical trials in the new millennium
Authors: DeMets David L.
Published: October 2002

Since the introduction of the randomized clinical trial (RCT) over 50 years ago, this method has become the corner stone for evaluating new pharmacologic or biologic agents with many disease areas benefiting. There are numerous examples demonstrating beneficial interventions as well as others either not beneficial or harmful. Statistical methodology for clinical trials has grown rapidly. Advances in information technology for data collection have allowed trials to be conducted around the world. Academia, industry and government have worked in partnership to conduct RCTs. Despite these many RCT achievements, the most interesting and challenging era of clinical trials lies ahead of us. With the human genome now sequenced, we face a new set of challenges to transform vast amounts of data into useful information. The post‐genomics era will better identify the disease mechanism and thus help design better treatments, and be more selective in screening patients, yielding more efficient clinical trials. For some areas of medicine, such as medical devices, standards of acceptance and regulatory approval are changing. Other areas, such as medical procedures and alternative medicines, are generally not well evaluated and could benefit greatly from a wider use of RCT methodology. As the ICH guidelines facilitate and encourage international clinical trials, the scientific and ethical dimension of conducting trials in Third World countries are raised. For example, Western society's best standard of care may not be available or affordable to these countries as the control Western investigators should not exploit patients in the Third World. Those and many other challenges face us in the decade ahead. It is truly an exciting time with new opportunities for the RCT to contribute to medicine and health care or prevention. Copyright © 2002 John Wiley & Sons, Ltd.
Advanced issues in the design and conduct of randomized clinical trials: the bigger the better?
Authors: Warlow Charles
Published: October 2002

Large trials provide more precise estimates of treatment effects than small trial (how good is the treatment?) and they may allow a few sensible and pre‐defined sub‐group analyses (for whom does the treatment work best?). But large trials will not get done unless they are simple and as part of normal clinical practice as possible. Copyright © 2002 John Wiley & Sons, Ltd.
Policy developments in regulatory approval
Authors: Temple Robert
Published: October 2002

Although radical changes in drug regulation are rare (e.g., the Federal Food, Drug and Cosmetic Act of 1938 and the 1962 amendment to the Act creating an effectiveness requirement), regulations and guidance do evolve significantly in the face of new problems and accumulating experience. Recent changes have been driven by the Food and Drug Administration Modernization Act (FDAMA), user fee legislation, the International Conference on Harmonization, recent safety related drug withdrawals, and concerns about trial ethics and investigator conflict of interest.

FDAMA and guidance developed in response to it has helped circumstances in which FDA would rely on a single study to support effectiveness and the circumstances in which surrogate endpoints could support approval. An ICH Document ‘Choice of control group and related design issues in clinical trials’ focussed attention on the ethics of placebo controls (acceptable, even if there is existing therapy, when the placebo‐treated patient will suffer no irreversible injury) and the design of ‘equivalence’ or ‘non‐inferiority’ trials.

There has been greatly increased attention to obtaining good dose‐response information and to assessing need for modifying treatment in demographic (age, gender, race) and concomitant disease (renal or hepatic function abnormalities) subgroups, and in assessing drug–drug interactions.

Other important trends are increasing reliance on non‐U.S. data, increasing numbers of FDA‐industry meetings during drug development, and new focus on risk assessment and risk management. Published in 2002 by John Wiley & Sons, Ltd.
Issues in the meta‐analysis of cluster randomized trials
Authors: Donner Allan , Klar Neil
Published: October 2002

Meta‐analyses involving the synthesis of evidence from cluster randomization trials are being increasingly reported. These analyses raise challenging methodologic issues beyond those raised by meta‐analyses which include only individually randomized trials. In this paper we review and comment on a selected number of these issues, including problems of study heterogeneity, difficulties in estimating design effects from individual trials and the choice of statistical methods. Copyright © 2002 John Wiley & Sons, Ltd.
The changing context of campus safety
Authors: Rund James A.
Published: October 2002

As colleges and universities evolve, so too do the complexities of creating safe environments for students. This chapter describes safety in its various contexts and provides an overview for the volume.
Addressing ongoing safety issues
Authors: Young Michael , Nord Dennis L. , Harris Yonie
Published: October 2002

This chapter draws upon ongoing lessons for dealing with campus emergencies from a series of incidents, some high‐profile, that occurred at the University of California, Santa Barbara, during the 2000–2001 academic year.
Effect of acute and chronic administration of the selective 5‐HT2C receptor antagonist SB‐243213 on midbrain dopamine neurons in the rat: An in vivo extracellular single cell study
Authors: Blackburn Thomas P. , Minabe Yoshio , Middlemiss Derek N. , Shirayama Yukihiko , Hashimoto Kenji , Ashby Charles R.
Published: October 2002

In this study, we examined the effect of the acute and chronic administration of the selective 5‐HT2C receptor antagonist SB‐243213 (SB) on the activity of spontaneously active dopamine (DA) cells in the substantia nigra pars compacta (SNC) and ventral tegmental area (VTA) in anesthetized, albino, male Sprague‐Dawley rats. This was accomplished using the technique of in vivo extracellular single cell recording. The acute i.v. administration of SB‐243213 (0.025–3.2 mg/kg) did not significantly alter the basal firing rate or pattern of either spontaneously active SNC or VTA DA neurons compared to vehicle‐treated controls. The acute i.p. administration of either 1 or 10 mg/kg of SB‐243213 did not significantly alter the number of spontaneously active DA cells in the SNC or VTA compared to vehicle‐treated controls, whereas the 3 mg/kg dose only significantly decreased the number of spontaneously active VTA DA neurons. Overall, the 1 mg/kg dose of SB‐243213 did not significantly alter the firing pattern of either SNC or VTA DA neurons compared to vehicle‐treated controls. In contrast, the 3 mg/kg dose significantly altered the firing pattern of SNC DA neurons, whereas the 10 mg/kg dose altered the firing pattern of DA neurons in both the SNC and VTA. The repeated i.p. administration (21 days) of 1, 3, and 10 mg/kg of SB‐243213 or 20 mg/kg of clozapine produced a significant decrease in the number of spontaneously active DA cells in the VTA compared to vehicle‐treated controls. The decrease in the number of spontaneously active VTA DA cells was not reversed by the i.v. administration of (+)‐apomorphine (50 μg/kg). The repeated administration of either 1 or 3 mg/kg of SB‐243213 had minimal effects on the firing pattern of either SNC or VTA DA neurons. In contrast, the firing pattern of VTA DA neurons was significantly altered by 10 mg/kg dose of SB‐243213. Overall, our results indicate that antagonism of the 5‐HT2C receptor alters the activity of midbrain DA neurons in anesthetized rats and suggest that SB‐243213 has an atypical antipsychotic profile following chronic administration. Synapse 46:129–139, 2002. © 2002 Wiley‐Liss, Inc.
Brain imaging of18F‐fallypride in normal volunteers: Blood analysis, distribution, test‐retest studies, and preliminary assessment of sensitivity to aging effects on dopamine D‐2/D‐3 receptors
Authors: Mukherjee Jogeshwar , Christian Bradley T. , Dunigan Kelly A. , Shi Bingzhi , Narayanan Tanjore K. , Satter Martin , Mantil Joseph
Published: October 2002

Human studies of dopamine D2/D3 receptors using18F‐fallypride‐PET in normal volunteers were performed to evaluate brain distribution in striatal and extrastriatal regions, evaluate metabolites in blood plasma, establish PET imaging protocol for this new radiotracer, evaluate graphical methods of analysis to quantitate D2/D3 receptors, and assess the ability of18F‐fallypride to measure changes in D2/D3 receptors with aging as a model. Subjects (6; 21–63 years) had a PET scan on a Siemens HR+ scanner with18F‐fallypride and a T1‐weighted MRI scan on a 1.5T GE scanner for purposes of anatomical coregistration with PET. A 3‐h PET scan with18F‐fallypride (0.07 mCi/Kg) was carried out on each subject and repeated in 4–6 weeks. Arterial or arterialized venous blood was obtained in all subjects in order to evaluate blood activity levels and analyze metabolites in the plasma. Brain regions‐of‐interest were identified and drawn using PET and PET‐MR coregistered images. PET data was analyzed using graphical methods in which cerebellum was used as the reference region providing distribution volume ratios (DVR) from which binding potential (BP) was derived and used as a measure of concentration of receptors. Distribution of18F‐fallypride was consistent in all subjects studied and the rank order of receptor concentration was putamen > caudate > thalamus = pituitary > amygdala > colliculi > substantia nigra > hippocampus = temporal cortex > parietal cortex = occipital cortex = orbitofrontal cortex. For younger subjects, BP ranged from 37 for the putamen to 0.4 for orbitofrontal cortex, with a test–retest error of about 10%. Both hydrophilic and lipophilic metabolites were observed in arterial blood plasma and analyses showed approx. 30–40% of plasma radioactivity at 3 h was18F‐fallypride. With aging, all brain regions exhibited a significant decrease (>10% per decade) in binding of18F‐fallypride. PET studies with18F‐fallypride are thus suitable to study changes in D2/D3 receptors in striatal and extrastriatal brain regions. Synapse 46:170–188, 2002. © 2002 Wiley‐Liss, Inc.
Design‐to‐market integrating conceptual design and marketing
Authors: Vollerthun Andreas
Published: October 2002

This article presents an approach to integrate conceptual design and marketing by using a systems engineering approach. A methodology is applied that has successfully linked conceptual design with cost modeling to now also integrate marketing considerations. By combining technical product models and cost models with a market model in one integrated model, an added value is generated: Systems engineers can analyze entire business cases. The paper describes how the market model works, shows the interfaces to conceptual design and cost modeling, and discusses the integration into the overall design process. The full model is applied to the development of the European satellite navigation system “Galileo.” Development teams can easily change parameters in the design and analyze the effects of these changes on, for example, market revenues. To quantify differences among design alternatives, two approaches are considered: (a) a measure of effectiveness (market robustness) and (b) cash‐flow curves to model, simulate, and evaluate entire business cases. © 2002 Wiley Periodicals, Inc. Syst Eng 5: 315–326, 2002
Synthesis of Silylene and Silyl(silylene)metal Complexes
Authors: Ogino Hiroshi
Published: October 2002

In 1987, two research groups published the first‐ever reports on the synthesis of silylene complexes and presented structural evidence. Since then, a range of synthetic methods have been developed and a number of silylene complexes have been prepared. In 1988, we reported on the first base‐stabilized bis(silylene) complexes that can be regarded as being masked silyl(silylene) complexes. These complexes occupy a unique position among silylene and silyl(silylene) complexes in that they provide a convenient tool for studying the reactivity of coordinated silylenes. They are stable enough to be isolated, but the bond between the silylene silicon atom and the internal base can easily be cleaved by thermal perturbation to generate real silyl(silylene) complexes. To date, a number of base‐stabilized bis(silylene) complexes have been prepared in which the central metals range from group 5 to group 9. Only two base‐free silyl(silylene) complexes have been prepared. One is prepared by reacting a platinum complex with a stable silylene; the other is produced by the photolysis of a tungsten complex in the presence of a hydrodisilane. © 2002 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 2: 291–306, 2002: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10034
From “Parasitic” Association Reactions toward the Stoichiometry Controlled Gas Phase Synthesis of Nanoparticles: A Theoretically Driven Challenge for Experimentalists
Authors: Timoshkin Alexey Y. , Schaefer Henry F.
Published: October 2002

In the present record a model for the gas‐phase reactions during the chemical vapor deposition (CVD) processes of group 13–15 materials is presented, based on the results of extensive quantum‐chemical modeling. Thermodynamic criteria have been introduced to evaluate the importance of a range of association reactions. For the organometallic and hydride derivatives, association processes are found to be favorable both thermodynamically and kinetically. Formation of high mass association products takes place under CVD conditions, including laser‐assisted CVD. Structural and thermodynamic properties of the most important ring and cluster intermediates have been predicted. The stoichiometry‐controlled synthesis of the 13–15 ternary alloys and nanoparticles using cluster compounds as single‐source precursors is predicted to be viable. The association pathway described may be generalized to the CVD reactions of many binary materials (12–16, 13–16, 13–15, 14–15, 14–16). © 2002 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 2: 319–338, 2002: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10037
Undergraduates' attitudes and beliefs about subject matter and pedagogy measured periodically in a reform‐based mathematics and science teacher preparation program
Authors: McGinnis J. Randy , Kramer Steve , Shama Gilli , Graeber Anna O. , Parker Carolyn A. , Watanabe Ted
Published: October 2002

This study describes the design and use of a valid and reliable instrument to measure teacher candidates' attitudes and beliefs about mathematics and science and the teaching of those subjects. The instrument, Attitudes and Beliefs about the Nature of and the Teaching of Mathematics and Science, was developed for the Maryland Collaborative for Teacher Preparation (MCTP), a statewide, standards‐based project in the National Science Foundation's Collaborative in Excellence in Teaching Preparation (CETP) Program. We report on two applications of the instrument: (a) a contrast between MCTP teacher candidates' and non‐MCTP teacher candidates' attitudes and beliefs about mathematics and science as they initially encountered reform‐based instruction in their undergraduate courses, and (b) a landscaping of how the MCTP teacher candidates' attitudes toward and beliefs about mathematics and science evolved over a 2.5‐year period. In support of current reform in science and mathematics teacher education, we determined that over an extended period the MCTP teacher candidates' attitudes and beliefs moved substantively and significantly in the direction intended. However, we also found that the non‐MCTP teacher candidates in the same reform‐based courses did not mirror this improvement in their attitudes and beliefs about mathematics and science or the teaching of those subjects. © 2002 Wiley Periodicals, Inc. J Res Sci Teach 39: 713–737, 2002
Assessing field experiences
Authors: Puckett Jane B. , Anderson Rebecca S.
Published: October 2002

The movement toward on‐line learning presents challenges for professional preparation programs where field experiences are a traditional part of the course of study. Can professors effectively monitor and assess real‐world experiences using the Internet?
Epilogue: A cautionary note about on‐line assessment
Authors: Bothel Richard Thomas
Published: October 2002

The effectiveness of on‐line assessment is challenged by several significant factors: unrealistic appraisal of the potential of on‐line education, enforcement of a code of conduct, and computer and telecommunication skills bias and other limitations of on‐line media.
Classifying class I and class II compounds by hydrophobicity and hydrogen bonding descriptors
Authors: Ren S.
Published: October 2002

The successful development of quantitative structure‐activity relationships (QSARs) and the prediction of toxicity based on QSARs depend on the correct classification of the mechanism of toxic action of chemical compounds. The toxicity mechanism of a compound can be determined by a few existing methods, such as studying the chemical structure of the compound for certain substructures and assigning a mechanism accordingly. However, these methods are less reliable for compounds with complex structures and are usually complicated. A novel descriptor‐based method employing a multivariate statistical technique—discriminant analysis—was developed in this study for the classification of class I and class II compounds. The discriminating variables used in discriminant analysis were the hydrophobicity descriptor log(Kow) and the hydrogen bonding descriptors ELUMO, EHOMO, Q+, and Q−. Because only numerical values of these descriptors are required for this method, which can be calculated, no additional experimental work was required for the toxicity mechanism classification of new compounds. A nonlinear discriminant function was generated that could not be expressed explicitly. Assessing the predicting ability of the discriminant function by the cross‐validation method showed that a low total error rate, 4.2% was achieved. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 415–423, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10074
Quests in a tetherless world
Authors: Bisdikian Chatschik , Hild Stefan , Lee Nathan , Perret Veronique , Naghshineh Mahmoud
Published: October 2002

Wireless research activities span a wide range of disciplines: communications engineering, software engineering and computer sciences covering all aspects of communication and services including client platforms and server deployment, network protocols and infrastructure, service development and deployment and so on. Our research group at the IBM T. J. Watson Research Center has initiated a number of research activities covering several aspects of the wireless research. In this paper, we highlight our work on the Bluetooth™ wireless technology and the BlueDrekar™ software stack, the WebSplitter middleware for content distribution, and we will share our vision for interconnecting trillion devices. Copyright © 2002 John Wiley & Sons, Ltd.