bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of the purinergic receptor subtype on guinea‐pig suburothelial myofibroblasts
Authors: SUI GUI‐PING , WU CHANGHAO , FRY CHRISTOPHER H.
Published: May 2006

OBJECTIVE

To identify particular purinoceptor subtypes by immunohistochemical labelling, as a layer of suburothelial myofibroblasts has been identified in the urinary bladder, and these cells respond to exogenous ATP by generating an intracellular Ca2+transient, but the particular purinoceptor that responds to ATP is unclear.

MATERIALS AND METHODS

Tissue sections and isolated cells from the urothelial layer of the guinea‐pig bladder were used. Preparations were labelled with primary antibodies to the intermediate‐filament protein, vimentin, or the purinoceptors P2X3, P2Y1, P2Y2, P2Y4and P2Y6. For single‐labelling we used a secondary antibody tagged with the fluorescent marker Cy3, and for double‐labelling also a secondary antibody tagged with fluorescein isothiocyanate or Cy2. Images were examined using a confocal microscope, with an argon (488 nm) or helium‐neon (543 nm) laser.

RESULTS

Vimentin‐labelling was confined to the suburothelial layer and appeared as discrete signals. Isolated cells labelled with vimentin and strongly for the P2Y6antibody. There was weaker staining for P2X3, P2Y2and P2Y4, but none to P2Y1. With frozen sections there was P2Y6labelling in the urothelial and suburothelial layer.

CONCLUSION

The predominant purinoceptor in suburothelial myofibroblasts, from these labelling studies, is the P2Y6subtype. However, there was weaker labelling to other subtypes, suggesting multiple receptor subtypes or heterogeneity of receptor subunits. The consequences of there being multiple purinoceptor subtypes in the suburothelial space with respect to sensory signalling are discussed.
Testing differential effects of computer‐based, web‐based and paper‐based administration of questionnaire research instruments
Authors: Hardré Patricia L. , Crowson H. Michael , Xie Kui , Ly Cong
Published: May 2006

Translation of questionnaire instruments to digital administration systems, both self‐contained and web‐based, is widespread and increasing daily. However, the literature is lean on controlled empirical studies investigating the potential for differential effects of administrative methods. In this study, two university student samples were administered 16 questionnaires across three separate administration conditions: paper‐based, computer‐based and web‐based. Outcomes of interest included data quality and participant affect. Overall, few differences in data quality were observed between administration conditions despite some evidence in favour of paper‐based administration (PBA) over the other two. Affective responses of participants favoured the PBA over web‐ and computer‐based administrations. Implications for research use of digital systems for data collection are discussed.
Trust in Testimony: How Children Learn About Science and Religion
Authors: Harris Paul L. , Koenig Melissa A.
Published: May 2006

Many adult beliefs are based on the testimony provided by other people rather than on firsthand observation. Children also learn from other people's testimony. For example, they learn that mental processes depend on the brain, that the earth is spherical, and that hidden bodily organs constrain life and death. Such learning might indicate that other people's testimony simply amplifies children's access to empirical data. However, children's understanding of God's special powers and the afterlife shows that their acceptance of others' testimony extends beyond the empirical domain. Thus, children appear to conceptualize unobservable scientific and religious entities similarly. Nevertheless, some children distinguish between the 2 domains, arguably because a different pattern of discourse surrounds scientific as compared to religious entities.
Cognitive Development, Culture, and Conversation: Comments on Harris and Koenig's “Truth in Testimony: How Children Learn about Science and Religion”
Authors: Callanan Maureen A.
Published: May 2006

Harris and Koenig make a compelling case for the importance of adult “testimony” and its influence on children's developing conceptions of topics in science and religion. This commentary considers how their analysis relates to constructivist and sociocultural theories and discusses several ways in which Harris and Koenig's arguments help to debunk some prevalent assumptions about research on the social context of cognitive development. Finally, a number of additional issues are raised for debate and discussion, and some critiques and suggestions for future research are discussed. The issues discussed by Harris and Koenig are crucial if we are to take seriously the importance of culture in cognitive development.
Extending the Testimony Problem: Evaluating the Truth, Scope, and Source of Cultural Information
Authors: Bergstrom Brian , Moehlmann Bianca , Boyer Pascal
Published: May 2006

Children's learning—in the domains of science and religion specifically, but in many other cultural domains as well—relies extensively on testimony and other forms of culturally transmitted information. The cognitive processes that enable such learning must also administrate the evaluation, qualification, and storage of that information, while guarding against the dangers of false or misleading input. Currently, the development of these appraisal processes is not clearly understood. Recent work, reviewed here, has begun to address three important dimensions of the problem: how children and adults evaluatetruthin communication, how they gauge theinferential potentialof information, and how they encode and evaluate itssource.
Longitudinal Trajectories of Self‐System Processes and Depressive Symptoms Among Maltreated and Nonmaltreated Children
Authors: Kim Jungmeen , Cicchetti Dante
Published: May 2006

This study used latent growth modeling to investigate longitudinal relationships between self‐system processes and depressive symptoms among maltreated (n=142) and nonmaltreated children (n=109) aged 6–11 years. On average, self‐esteem and self‐agency increased and depressive symptoms decreased over time. Multivariate growth modeling indicated that, regardless of gender, physical abuse was negatively related to initial levels of self‐esteem, and physical abuse and physical neglect were positively associated with initial levels of depressive symptoms. Emotional maltreatment was predictive of changes in self‐esteem and changes in depressive symptoms. Initial levels of self‐esteem were negatively associated with initial levels of depressive symptoms. The findings contribute to enhancing our understanding of the developmental processes whereby early maltreatment experiences are linked to later maladjustment.
Do the Effects of Early Severe Deprivation on Cognition Persist Into Early Adolescence? Findings From the English and Romanian Adoptees Study
Authors: Beckett Celia , Maughan Barbara , Rutter Michael , Castle Jenny , Colvert Emma , Groothues Christine , Kreppner Jana , Stevens Suzanne , O'Connor Thomas G. , Sonuga‐Barke Edmund J. S.
Published: May 2006

Cognitive outcomes at age 11 of 131 Romanian adoptees from institutions were compared with 50 U.K. adopted children. Key findings were of both continuity and change: (1) marked adverse effects persisted at age 11 for many of the children who were over 6 months on arrival; (2) there was some catch‐up between ages 6 and 11 for the bottom 15%; (3) there was a decrease of 15 points for those over 6 months on arrival, but no differentiation within the 6–42‐month range; (4) there was marked heterogeneity of outcome but this was not associated with the educational background of the adoptive families. The findings draw attention to the psychological as well as physical risks of institutional deprivation.
Relations Between Maternal Input and Theory of Mind Understanding in Deaf Children
Authors: Moeller Mary Pat , Schick Brenda
Published: May 2006

This study investigates the relationship between theory of mind (ToM) skills in deaf children and input from their hearing mothers. Twenty‐two hearing mothers and their deaf children (ages 4–10 years) participated in tasks designed to elicit talk about the mind. The mothers' mental state talk was compared with that of 26 mothers with hearing children (ages 4–6 years). The frequency of mothers' mental talk was correlated with deaf children's performance on ToM tasks, after controlling for effects of child language and age. Maternal sign proficiency was correlated with child language, false belief, and mothers' talk about the mind. Findings are discussed in relation to experiential accounts of ToM development and roles of maternal talk in children's social understanding.
Counting‐On, Trading and Partitioning: Effects of Training and Prior Knowledge on Performance on Base‐10 Tasks
Authors: Saxton Matthew , Cakir Kadir
Published: May 2006

Factors affecting performance on base‐10 tasks were investigated in a series of four studies with a total of 453 children aged 5–7 years. Training in counting‐on was found to enhance child performance on base‐10 tasks (Studies 2, 3, and 4), while prior knowledge of counting‐on (Study 1), trading (Studies 1 and 3), and partitioning (Studies 1 and 4) were associated with enhanced base‐10 performance. It emerged that procedural knowledge of counting‐on, trading, and partitioning can lead to improvements in procedural knowledge of the base‐10 system. The findings lend support to the model of iterative development of conceptual and procedural knowledge advanced by Rittle‐Johnson et al. (2001).
Potential of trophy hunting to create incentives for wildlife conservation in Africa where alternative wildlife‐based land uses may not be viable
Authors: Lindsey P. A. , Alexander R. , Frank L. G. , Mathieson A. , Romañach S. S.
Published: May 2006

There is a lack of consensus among conservationists as to whether trophy hunting represents a legitimate conservation tool in Africa. Hunting advocates stress that trophy hunting can create incentives for conservation where ecotourism is not possible. We assessed the hunting preferences of hunting clients who have hunted or plan to hunt in Africa (n=150), and the perception among African hunting operators (n=127) of client preferences at two US hunting conventions to determine whether this assertion is justified. Clients are most interested in hunting in well‐known East and southern African hunting destinations, but some trophy species attract hunters to remote and unstable countries that might not otherwise derive revenues from hunting. Clients are willing to hunt in areas lacking high densities of wildlife or attractive scenery, and where people and livestock occur, stressing the potential for trophy hunting to generate revenues where ecotourism may not be viable. Hunting clients are more averse to hunting under conditions whereby conservation objectives are compromised than operators realize, suggesting that client preferences could potentially drive positive change in the hunting industry, to the benefit of conservation. However, the preferences and attitudes of some clients likely form the basis of some of the problems currently associated with the hunting industry in Africa, stressing the need for an effective regulatory framework.
Seduced by the dark side: integrating molecular and ecological perspectives on the influence of light on plant defence against pests and pathogens
Authors: Roberts Michael R. , Paul Nigel D.
Published: May 2006

Plants frequently suffer attack from herbivores and microbial pathogens, and have evolved a complex array of defence mechanisms to resist defoliation and disease. These include both preformed defences, ranging from structural features to stores of toxic secondary metabolites, and inducible defences, which are activated only after an attack is detected. It is well known that plant defences against pests and pathogens are commonly affected by environmental conditions, but the mechanisms by which responses to the biotic and abiotic environments interact are only poorly understood. In this review, we consider the impact of light on plant defence, in terms of both plant life histories and rapid scale molecular responses to biotic attack. We bring together evidence that illustrates that light not only modulates defence responses via its influence on biochemistry and plant development but, in some cases, is essential for the development of resistance. We suggest that the interaction between the light environment and plant defence is multifaceted, and extends across different temporal and biological scales.

Contents

Summary
677

I.
Introduction
678

II.
Light as an environmental variable
678

III.
Long‐term effects of light on plant–herbivore or plant–pathogen interactions
679

IV.
Mechanisms of responses to the light environment: the whole‐plant perspective
684

V.
Short‐term responses to the light environment: induced defences
686

VI.
Mechanisms for light‐dependent induced defences
688

VII.
Interpreting interactions between light and defence responses
690

Acknowledgements
693

References
693
Genes, enzymes and chemicals of terpenoid diversity in the constitutive and induced defence of conifers against insects and pathogens*
Authors: Keeling Christopher I. , Bohlmann Jörg
Published: May 2006

Insects select their hosts, but trees cannot select which herbivores will feed upon them. Thus, as long‐lived stationary organisms, conifers must resist the onslaught of varying and multiple attackers over their lifetime. Arguably, the greatest threats to conifers are herbivorous insects and their associated pathogens. Insects such as bark beetles, stem‐ and wood‐boring insects, shoot‐feeding weevils, and foliage‐feeding budworms and sawflies are among the most devastating pests of conifer forests. Conifer trees produce a great diversity of compounds, such as an enormous array of terpenoids and phenolics, that may impart resistance to a variety of herbivores and microorganisms. Insects have evolved to specialize in resistance to these chemicals – choosing, feeding upon, and colonizing hosts they perceive to be best suited to reproduction. This review focuses on the plant–insect interactions mediated by conifer‐produced terpenoids. To understand the role of terpenoids in conifer–insect interactions, we must understand how conifers produce the wide diversity of terpenoids, as well as understand how these specific compounds affect insect behaviour and physiology. This review examines what chemicals are produced, the genes and proteins involved in their biosynthesis, how they work, and how they are regulated. It also examines how insects and their associated pathogens interact with, elicit, and are affected by conifer‐produced terpenoids.

Contents

Summary
657

I.
Introduction
658

II.
Identification and functional characterization of  terpenoid pathway genes
658

III.
Insect interactions with conifers
667

IV.
Conclusions and outlook
670

Acknowledgements
671

References
671
Interpersonal chemistry through negativity: Bonding by sharing negative attitudes about others
Authors: BOSSON JENNIFER K. , JOHNSON AMBER B. , NIEDERHOFFER KATE , SWANN WILLIAM B.
Published: May 2006

We propose that sharing a negative—as compared to a positive—attitude about a third party is particularly effective in promoting closeness between people. Findings from two survey studies and an experiment support this idea. In Studies 1 and 2, participants’ open‐ended responses revealed a tendency to recall sharing with their closest friends more negative than positive attitudes about other people. Study 3 established that discovering a shared negative attitude about a target person predicted liking for a stranger more strongly than discovering a shared positive attitude (but only when attitudes were weak). Presumably, sharing negative attitudes is alluring because it establishes in‐group/out‐group boundaries, boosts self‐esteem, and conveys highly diagnostic information about attitude holders. Despite the apparent ubiquity of this effect, participants seemed unaware of it. Instead, they asserted that sharing positive attitudes about others would be particularly effective in promoting closeness.
Dialyzer Reuse—Part II: Advantages and Disadvantages
Authors: Twardowski Zbylut J.
Published: May 2006

Although single dialyzer use and reuse by chemical reprocessing are both associated with some complications, there is no definitive advantage to either in this respect. Some complications occur mainly at the first use of a dialyzer: a new cellophane or cuprophane membrane may activate the complement system, or a noxious agent may be introduced to the dialyzer during production or generated during storage. These agents may not be completely removed during the routine rinsing procedure. The reuse of dialyzers is associated with environmental contamination, allergic reactions, residual chemical infusion (rebound release), inadequate concentration of disinfectants, and pyrogen reactions. Bleach used during reprocessing causes a progressive increase in dialyzer permeability to larger molecules, including albumin. Reprocessing methods without the use of bleach are associated with progressive decreases in membrane permeability, particularly to larger molecules. Most comparative studies have not shown differences in mortality between centers reusing and those not reusing dialyzers, however, the largest cluster of dialysis‐related deaths occurred with single‐use dialyzers due to the presence of perfluorohydrocarbon introduced during the manufacturing process and not completely removed during preparation of the dialyzers before the dialysis procedure. The cost savings associated with reuse is substantial, especially with more expensive, high‐flux synthetic membrane dialyzers. With reuse, some dialysis centers can afford to utilize more efficient dialyzers that are more expensive; consequently they provide a higher dose of dialysis and reduce mortality. Some studies have shown minimally higher morbidity with chemical reuse, depending on the method. Waste disposal is definitely decreased with the reuse of dialyzers, thus environmental impacts are lessened, particularly if reprocessing is done by heat disinfection. It is safe to predict that dialyzer reuse in dialysis centers will continue because it also saves money for the providers. Saving both time for the patient and money for the provider were the main motivations to design a new machine for daily home hemodialysis. The machine, developed in the 1990s, cleans and heat disinfects the dialyzer and lines in situ so they do not need to be changed for a month. In contrast, reuse of dialyzers in home hemodialysis patients treated with other hemodialysis machines is becoming less popular and is almost extinct.
Steady‐State Solutions to PBPK Models and Their Applications to Risk Assessment I: Route‐to‐Route Extrapolation of Volatile Chemicals
Authors: Chiu Weihsueh A. , White Paul
Published: May 2006

Although analysis of in vivo pharmacokinetic data necessitates use of time‐dependent physiologically‐based pharmacokinetic (PBPK) models, risk assessment applications are often driven primarily by steady‐state and/or integrated (e.g., AUC) dosimetry. To that end, we present an analysis of steady‐state solutions to a PBPK model for a generic volatile chemical metabolized in the liver. We derive an equivalent model that is much simpler and contains many fewer parameters than the full PBPK model. The state of the system can be specified by two state variables—the rate of metabolism and the rate of clearance by exhalation. For a given oral dose rate or inhalation exposure concentration, the system state only depends on the blood‐air partition coefficient, metabolic constants, and the rates of blood flow to the liver and of alveolar ventilation. At exposures where metabolism is close to linear, only the effective first‐order metabolic rate is needed. Furthermore, in this case, the relationship between cumulative exposure and average internal dose (e.g., AUCs) remains the same for time‐varying exposures. We apply our analysis to oral‐inhalation route extrapolation, showing that for any dose metric, route equivalence only depends on the parameters that determine the system state. Even if the appropriate dose metric is unknown, bounds can be placed on the route‐to‐route equivalence with very limited data. We illustrate this analysis by showing that it reproduces exactly the PBPK‐model‐based route‐to‐route extrapolation in EPA's 2000 risk assessment for vinyl chloride. Overall, we find that in many cases, steady‐state solutions exactly reproduce or closely approximate the solutions using the full PBPK model, while being substantially more transparent. Subsequent work will examine the utility of steady‐state solutions for analyzing cross‐species extrapolation and intraspecies variability.
Policing Urban America: A New Look at the Politics of Agency Size*
Authors: Sharp Elaine B.
Published: May 2006

Objectives.This article analyzes competing explanations for variation in the relative size of contemporary police forces in larger U.S. cities. The featured explanation is conflict theory, which previously provided much evidence for a racial threat thesis but limited evidence that racial insurgency affected police mobilization in the 1960s and 1970s.

Methods.The study sample consists of the 66 cities with a population of at least 250,000 in 2000. Aggregate data from the Bureau of Justice Statistics, Congressional Quarterly'sAmerica Votes, and the U.S. Census Bureau are combined with a content analysis using the Lexis‐Nexis regional news database to generate the data set. OLS regression modeling is applied to the analysis of this cross‐sectional data set.

Results.This analysis shows that the size of contemporary police forces is substantially shaped not only by the legacy of the 1960–1970 wave of racial unrest in the United States, but also by reaction to racial disorders in the 1980s and 1990s and by the prevalence of racial minorities in the current population.

Conclusions.Police departments' relative force size in 2000 is not only a result of incremental growth from the size attained by 1980, but also is dramatically shaped by whether the city experienced a race riot from 1980–2000 and, to a lesser extent, the size of the minority population and the violent crime rate. City wealth is a less robust indicator; and there is no evidence that either community ideology or the degree of uptake of community policing matters.
Changing Ethical Attitudes: The Case of the Enron and ImClone Scandals*
Authors: Conroy Stephen J. , Emerson Tisha L. N.
Published: May 2006

Objective. We analyze the process of changing ethical attitudes over time by focusing on a specific set of “natural experiments” that occurred over an 18‐month period, namely, the accounting scandals that occurred involving Enron/Arthur Andersen and insider‐trader allegations related to ImClone.

Methods. Given the amount of media attention devoted to these ethical scandals, we test whether respondents in a cross‐sectional sample taken over 18 months become less accepting of ethically charged vignettes dealing with “accounting tricks” and “insider trading” over time.

Results. We find a significant and gradual decline in the acceptance of the vignettes over the 18‐month period.

Conclusions. Findings presented here may provide valuable insight into potential triggers of changing ethical attitudes. An intriguing implication of these results is that recent highly publicized ethical breaches may not be only a symptom, but also a cause of changing attitudes.
National Determinants of Cloning Policy*
Authors: Stabile Bonnie
Published: May 2006

Objective. This research seeks to identify demographic factors that may account for national stance toward human cloning.

Methods. A multiple logistic regression model serves as the basis for analysis. Cloning policy stance is characterized as restrictive or permissive, depending on whether the nation has expressed support for therapeutic cloning research—all nations oppose reproductive cloning.

Results. Findings suggest that nations with higher per‐capita incomes and permissive abortion laws are more likely to take a permissive stance toward cloning, supporting an immediate ban on human reproductive cloning, but allowing therapeutic cloning research to proceed. Countries favoring an immediate and total ban on both human reproductive and therapeutic cloning are more likely to have lower per‐capita incomes and restrictive abortion laws. A relationship between the Roman Catholic population and cloning stance was investigated and found not to be significant.

Conclusions. This article offers evidence that there may be systematic differences predisposing individual nations to act either restrictively or permissively with regard to cloning technology. Understanding the factors that shape sentiment and impel policy making may help inform the policy process as nations strive to create workable cloning policies both within their own borders and in the global community.
VISCOELASTICITY OF A SIMULATED POLYMER AND COMPARISON WITH CHICKPEA FLOUR DOUGHS
Authors: YADAV NIDHI , ROOPA B.S. , BHATTACHARYA SUVENDU
Published: May 2006

An integrated approach consisting of compression and stress relaxation is performed with a simulated model system of poly dimethyl siloxane (PDMS), a viscoelastic polymer material when the compressive strain, height of sample and crosshead speed were varied. The parameters derived are the forces at the end of compression and relaxation, energy for compression and the extent of elasticity of the sample based on the ratios of forces as well as the proposed energy values. The results were verified with food doughs undergoing large deformations that show a nonlinear behavior. The proposed extent of elasticity based on the ratios of energy stored and compression can be used as an index for the characterization of viscoelasticity. A nonlinear three‐parameter model had also been proposed to predict the stress decay characteristics as a function of time, which was found suitable for the PDMS system, and was better than the two‐parameter Peleg model as judged by lower variance values (0.0006–0.018 and 0.002–0.048, respectively). Further, an actual system of food doughs in the form of chickpea (Cicer arietinum L.) flour dough was used to verify the proposed model and viscoelastic index at different moisture contents (27–39%) subjected to compressive strains of 25–75%. The nonlinear relaxation characteristics of the food dough are sensitive to moisture content as well as to strain level.
THE THERMAL STABILITY OF ASPERGILLUS ORYZAE ALPHA‐AMYLASE IN PRESENCE OF SUGARS AND POLYOLS
Authors: SAMBORSKA K. , GUIAVARC'H Y. , VAN LOEY A. , HENDRICKX M.
Published: May 2006

The aim of this study was to test whether it is possible to estimate the heat stability of Aspergillus oryzae alpha‐amylase (α‐amylase) based on the amount of hydroxyl (OH) groups provided in a buffer solution. The thermal stability of the enzyme in a presence of different sugars (sucrose and trehalose) and polyols (mannitol, sorbitol, lactitol and glycerol) was investigated in the temperature range of 62–68C on a kinetic basis.

It was investigated if the protective effect of additional substances was correlated to the number of hydroxyl groups (nOH) provided by each of them (per volume unit of the enzyme solution nOH).

All additives showed a protective effect on the enzyme's heat stability, which was strongly dependent on the added compound concentration. Among all stabilizing compounds investigated, sucrose exhibited the largest protective effect. The decimal reduction time of α‐amylase activity increased by 33.9 times when 420 mg/mL of sucrose was added to the environment. When the same concentration of trehalose was used, the D‐value increased by 6.4 times compared to the value in the buffer system. The nOH provided in the enzyme solution could not be related to the D‐values for the enzyme thermal inactivation, meaning that the enzyme heat stability was not dependent on the nOH.
SUPERHEATED STEAM‐DRYING OF MATE LEAVES AND EFFECT OF DRYING CONDITIONS ON THE PHENOL CONTENT
Authors: ZANOELO EVERTON FERNANDO , CARDOZO‐FILHO LÚCIO , CARDOZO‐JÚNIOR EUCLIDES LARA
Published: May 2006

Four drying experiments of mate leaves (Ilex paraguariensis St. Hilaire) were carried out in a packed bed superheated steam dryer by varying outlet steam temperature from 120 to 140C and equivalent particle diameter from 4.7 × 10−3 to 6.95 × 10−3 m. The influence of these variables on the drying coefficient calculated by assuming a simplified drying kinetic model was investigated. A classical statistical approach revealed the significant effect of both factors on this parameter. Two additional drying runs were performed at identical conditions with conventional hot air and low pressure superheated steam, respectively. The influence of drying atmosphere on the total content of phenols was evaluated. A conventional process of extraction by using an aqueous methanol solution was adopted. Analyses for total phenols were performed by spectrophotometry at 715 nm by applying Folin‐Denis assay. The leaves dried with superheated steam had approximately 47% higher retention of these compounds.
Dynamic and Compliant Characteristics of a Cartesian-Guided Tripod Machine
Authors: Chen Jeng-Shyong , Hsu Wei-Yao
Published: May 2006

This paper is focused on the dynamic and compliant characteristics of a three-axis parallel kinematic machine called a Cartesian-guided tripod (CGT), which has a passive leg locking the platform three rotational degrees of freedom. Because no constraint mechanism is perfect with infinite rigidity, a compliance model has been developed to determine the maximum amplitude of the passive-leg parasitic motions using given loads. System compliance, dynamic characteristics, vibration modes, and servo-contouring errors of the CGT driving system have also been evaluated under high-speed machining conditions. The nonlinear dynamic effects, such as inertia and gravity, can be controlled within acceptable accuracy using the high-gain servo-feedback control techniques. The CGT dominant flexible mode occurs on the horizontal platform-leg vibration. The platform-leg flexible mode can produce significant jerk-induced mechanical vibration on the platform when a sudden velocity change is commanded. Look-ahead Cartesian-based path acceleration and deceleration control was found to be an efficient tool to reduce the jerk-induced mechanical vibration, although the CGT was drive controlled at the joint level. It was found that at high acceleration application, such as high-speed mold and die machining, the elastic elongation of the driving leg caused by the high acceleration force became the dominant contouring error sources.
Predictive Analytical and Thermal Modeling of Orthogonal Cutting Process—Part I: Predictions of Tool Forces, Stresses, and Temperature Distributions
Authors: Karpat Yiğit , Özel Tuğrul
Published: May 2006

In this paper, a predictive thermal and analytical modeling approach for orthogonal cutting process is introduced to conveniently calculate forces, stress, and temperature distributions. The modeling approach is based on the work material constitutive model, which depends on strain, strain rate, and temperature. In thermal modeling, oblique moving band heat source theory is utilized and analytically combined with modified Oxley’s parallel shear zone theory. Normal stress distribution on the tool rake face is modeled as nonuniform with a power-law relationship. Hence, nonuniform heat intensity at the tool-chip interface is obtained from the predicted stress distributions utilizing slip line field analysis of the modified secondary shear zone. Heat sources from shearing in the primary zone and friction at the tool-chip interface are combined, heat partition ratios are determined for temperature equilibrium to obtain temperature distributions depending on cutting conditions. Model validation is performed by comparing some experimental results with the predictions for machining of AISI 1045 steel, AL 6082-T6, and AL 6061-T6 aluminum. Close agreements with the experiments are observed. A set of detailed, analytically computed stress and temperature distributions is presented.
Predictive Analytical and Thermal Modeling of Orthogonal Cutting Process—Part II: Effect of Tool Flank Wear on Tool Forces, Stresses, and Temperature Distributions
Authors: Karpat Yiğit , Özel Tuğrul
Published: May 2006

In this paper, predictive modeling of cutting and ploughing forces, stress distributions on tool faces, and temperature distributions in the presence of tool flank wear are presented. The analytical and thermal modeling of orthogonal cutting that is introduced in Part I of the paper is extended for worn tool case in order to study the effect of flank wear on the predictions. Work material constitutive model based formulations of tool forces and stress distributions at tool rake and worn flank faces are utilized in calculating nonuniform heat intensities and heat partition ratios induced by shearing, tool-chip interface friction, and tool flank face-workpiece interface contacts. In order to model forces and stress distributions under the flank wear zone, a force model from Waldorf (1996) (“Shearing Ploughing, and Wear in Orthogonal Machining,” Ph.D. thesis, University of Illinois at Urbana-Champaign, IL) is adapted. Model is tested and validated for temperature and force predictions in machining of AISI 1045 steel and AL 6061-T6 aluminum.
Near-unity ideality factor diodes using nanocrystalline Si/multicrystalline Si heterojunctions for photovoltaic application
Authors: Farrokh-Baroughi Mahdi , Lee Czang-Ho , Sivoththaman Siva
Published: May 2006

High-quality heterojunction diodes with near-unity ideality factor were fabricated by direct deposition of a (n+) nanocrystalline silicon film on top of fine-grained (p) multicrystalline silicon substrates. A very good ideality factor of 1.08 was achieved using a single-diode model in the medium forward-bias regime. Current-voltage (IV) characteristics of the diodes measured in the dark show that the recombination at the heterointerface is much less than the recombination at the space-charge region in the low forward-bias regime confirming the fact that the junction quality is good and is suitable for photovoltaic applications. Internal quantum efficiency measurements performed on these cells show a high (>70%) blue response partly due to a high transparency of the n+ nanocrystalline material. Illuminated IV of the heterojunction solar cells show a high fill factor of 78%–79% and an acceptable open circuit voltage of 550mV for a simple structure without a rear-surface passivation or transparent conductive oxide.
Fabricating multilevel SU-8 structures in a single photolithographic step using colored masking patterns
Authors: Taff J. , Kashte Y. , Spinella-Mamo V. , Paranjape M.
Published: May 2006

The fabrication of multilevel SU-8 structures using a single photolithographic masking step is described. Preliminary data are presented on the use of photolithographic masks, containing millimeter-scale colored patterns, printed on transparent films using a standard color laser printer. The different colors printed on the photomask are shown to have differences in their UV absorptions, and hence different structure levels can be achieved from a single exposure. This method eliminates the pixelation problems encountered when using gray-scale masks (without employing photoreduction techniques) generated using a black-and-white laser printer. For research applications requiring rapid prototyping and fast turnaround times for large-scale features, this technique offers a cost-effective and time-efficient alternative to current three-dimensional lithography methods, which typically make use of multiple binary masks, alignment procedures, and exposures. Future applications will include the fabrication of textured PDMS surfaces and PDMS microfluidic substrates, cast from SU-8 molds processed using this technique.
Annealing temperature effect on the performance of nonvolatile HfO2 Si-oxide-nitride-oxide-silicon-type flash memory
Authors: Lin Yu-Hsien , Chien Chao-Hsin , Chang Chun-Yen , Lei Tan-Fu
Published: May 2006

In this article, we demonstrate the effect of the postdeposition annealing for the HfO2 trapping layer on the performance of the Si-oxide-nitride-oxide-silicon-type flash memories. It was found that the memory window becomes larger while the retention and endurance characteristics get worse as the annealing temperature increases. This was ascribed to the larger amount and the shallower energy levels of the crystallization-induced traps as compared to the traps presented in the as-fabricated HfO2 film. Finally, in the aspect of disturbances, we show only insignificant read, drain, and gate disturbances presented in the three samples in the normal operation.
Mechanical properties of Cu–Al–O thin films prepared by plasma-enhanced chemical vapor deposition
Authors: Chen Wen , Gong Hao , Zeng Kaiyang
Published: May 2006

Copper aluminum oxide thin films were prepared by the plasma-enhanced chemical vapor deposition from metal organic precursors. The film was characterized by x-ray diffraction, atomic force microscopy, and the depth profile analysis using secondary ion mass spectrometry. Nanoindentation was performed to measure the hardness and elastic modulus of the film. The mechanical strengthening of the film was considered to be due to nanograins of CuAlO2 and CuO throughout the film, the large area of grain boundaries, and also finer Al2O3 particles dispersed in the film matrix.
Hard multilayer coatings containing TiN and/or ZrN: A review and recent progress in their nanoscale characterization
Authors: Ziebert C. , Ulrich S.
Published: May 2006

In the first part of this article, a comprehensive literature review on hard multilayer coatings, which contain TiN and/or ZrN as a component is given. The developments made in this field, starting with the first published results in 1987 and ending with the latest articles in 2005, were summarized and critically evaluated in order to serve as a starting point for future research in this area. In the second part, recent progress in the nanoscale characterization of multilayers and their interfaces by the small-angle cross-section nanoindentation method and atomic force microscopy is demonstrated on TiN∕ZrN multilayers. These nanoscale multilayers were deposited by reactive dc-magnetron sputtering of metallic titanium and zirconium targets in argon/nitrogen plasma onto hard metal and silicon substrates.
Surfactant-assisted growth of CdS thin films for photovoltaic applications
Authors: Perkins Craig L. , Hasoon Falah S.
Published: May 2006

A common nonionic surfactant, Triton X-100, was used to modify the chemical bath deposition of CdS “buffer” layers on Cu(In,Ga)Se2 (CIGS) thin films. Addition of the surfactant to the CdS deposition bath allowed increased wetting of Cu(In,Ga)Se2 substrates and an increase in the uniformity of films, especially on model hydrophobic substrates. X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy data demonstrate that films produced with the surfactant have the same chemical and electronic properties as films grown without it. In CdS∕Cu(In,Ga)Se2 devices, it was found that Triton X-100 allowed the use of CdS layers that were three to four times thinner than those used normally in high efficiency CIGS-based devices and eliminated the large drops in open-circuit voltage that usually accompany very thin buffer layers. For these thin CdS layers and relative to devices made without the surfactant, average absolute cell efficiencies were increased from 10.5% to 14.8% or by a relative 41%. Visual inspection of the CdS depositions reveals one possible mechanism of the surfactant’s effects: Bubbles that form and adhere to the CIGS surface during the chemical bath deposition are almost completely eliminated with the addition of the TX-100. Thus, junction nonuniformities, pinholes, and thin areas in the CdS layer caused by poor wetting of the substrate surface are sharply reduced, leading to large increases in the open-circuit voltage in devices produced with the surfactant.
Effect of multipactor discharge on Alcator C-Mod ion cyclotron range of frequency heating
Authors: Graves T. P. , Wukitch S. J. , LaBombard B. , Hutchinson I. H.
Published: May 2006

Alcator C-Mod uses high power radio frequency (rf) power for auxiliary plasma heating at the ion cyclotron frequency. The operation of the rf antennas is limited at neutral pressures which fall far below the minimum pressure for glow discharge as given by the rf Paschen curve. Recent experiments have found that this operational pressure limit is due to multipactor discharges in the vacuum transmission lines. At elevated neutral pressures, the multipactor discharge induces a glow discharge that causes a nearly complete reflection of rf power. On C-Mod, in presence of a magnetic field, this discharge forms at pressures of 0.5 and 1mTorr, which are the same pressures as the observed operational limit. Experimental results are supported by the Coaxial Multipactor Experiment.
Synthesis and coordination chemistry of 2,2′-diboratabiphenyls
Authors: Ghesner Ioan , Piers Warren E , Parvez Masood , McDonald Robert
Published: May 2006

Dianionic 2,2′-diboratabiphenyl derivatives were prepared as a new class of binucleating ligands. Preliminary investigations into their coordination chemistry involved Rh complexes. Their solution and solid state structures were studied and confirm the preference for η6η6 coordination of the novel ligands, rendering them isoelectronic analogues of the ubiquitous bicyclopentadienyl system. Comparative studies suggest stronger donor properties for the fulvalene ligand as compared with the 2,2′-diboratabiphenyl system.Key words: dinucleating ligands, bimetallic complexes, rhodium complexes, boron heterocycles, X-ray structure.
Room-temperature NIR phosphorescence of new iridium (III) complexes with ligands derived from benzoquinoxaline
Authors: Chen Hsing-Yi , Yang Cheng-Han , Chi Yun , Cheng Yi-Ming , Yeh Yu-Shan , Chou Pi-Tai , Hsieh Hsi-Ying , Liu Chao-Shiuan , Peng Shie-Ming , Lee Gene-Hsiang
Published: May 2006

A new series of new iridium (III) complexes (15) bearing ligands derived from benzoquinoxaline were designed and synthesized. X-ray structural analyses of 1 reveal a distorted octahedral geometry around the Ir atom in which the pyrazolate chelate is located opposite to the cis-oriented carbon donor atoms of benzoquinoxaline, while the benzoquinoxaline ligands adopt an eclipse configuration and their coordinated nitrogen atoms and carbon adopt trans- and cis-orientation, respectively. Complexes 15 exhibit moderate NIR phosphorescence with peak maxima located at around 910930 nm. As supported by the TDDFT approach, the transition mainly involves benzoquinoxaline 3ππ* intraligand charge transfer (ILCT) and metal (Ir) to benzoquinoxaline charge transfer (MLCT) of which the spectroscopy and dynamics of relaxation have been thoroughly investigated. The relatively weak NIR emission can be tentatively rationalized by the low energy gap of which the radiationless deactivation may be governed by nearly temperature-independent, weak-bonding motions in combination with a minor channel incorporating small torsional motions associated with phenyl ring in the benzoquinoxaline sites.Key words: phosphorescence, NIR, iridium, benzoquinoxaline, isoquinoline, bipyridine, pyrazolate, acetylacetonate.
Small bite-angle diphosphines — Synthesis and structure of low-valent complexes of bis(di-ortho-tolylphosphino)methane (dotpm) and related ligands
Authors: Filby Maria , Deeming Antony J , Hogarth Graeme , Lee Mo-yin (Venus)
Published: May 2006

The coordination chemistry of bis(di-ortho-tolylphosphino)methane (dotpm) has been studied. It is an excellent chelating ligand and a range of low-valent mononuclear complexes have been prepared; cis-[M(CO)4(η2-dotpm)] (M = Cr, Mo, W; 1–3), [CpRuCl(η2-dotpm)] (4), and cis-[MX2(η2-dotpm)] (M = Pt, X = Cl, Br, I; 5a–5c, M = Pd, X = Cl; 6). The backbone protons are relatively acidic and can be deprotonated using n-BuLi or LiN(SiMe3)2. Subsequent alkylation by RX (X = halogen; R = Me, Et, CH2Ph) affords cis-[M(CO)4(η2-Rdotpm)] (M = Cr, Mo, W, R = Me; 7–9, M = Mo, W, R = Et, CH2Ph; 12–15), [CpRuCl(η2-Medotpm)] (10), and cis-[PtI2(η2-Medotpm)] (11). Thermolysis of cis-[Mo(CO)4(η2-Medotpm)] (8) yields what is believed to be the coordinately and electronically unsaturated complex [Mo(CO)3(η2-Medotpm)] (16), suggesting that derivatives of dotpm (cone angle 194°) are bulky enough to stabilize a 16-electron complex. Crystal structures of 2, 3, 7–9, 13, and 14 have been determined (diphosphine bite angles ranging from 66.58(3)° to 70.96(5)°.Key words: diphosphine, transition metal, bulky, carbonyl, ortho-tolyl.
A simple synthetic route to the formation of tetracopper(I) 2-mercaptothiazoline compounds  The crystal structures of [Cu4(S-thiaz)4(PEt2Ph)2], [Cu4(S-thiaz)4(PEt3)2], [Cu4(S-thiaz)4]2, and [Cu4(S-thiaz)4]4
Authors: Fuhr Olaf , Fernandez-Recio Lucia , Fenske Dieter
Published: May 2006

Reactions of copper(I) acetate with 2-mercaptothiazoline (HS-thiaz) in the presence of tertiary phosphines lead to the formation of tetranuclear sulphur-bridged copper complexes. Depending on the reaction conditions, isolated clusters ([Cu4(S-thiaz)4(PR3)2] (PR3 = PPh3 (1), PEt2Ph (2), PEt3 (3)), oligomeric compounds ([Cu4(S-thiaz)4]2 (4) and [Cu4(S-thiaz)4]4 (5)), or a one-dimensional polymer ([Cu4(S-thiaz)4]∞ (6)) are formed. The structures of the compounds 25 have been determined by single crystal X-ray analysis.Key words: copper, 2-mercaptothiazoline, single crystal X-ray analysis.
Areneperfluoroarene interactions in crystal engineering. Part 14. 1:1 Complexes of octafluoronaphthalene with fluorene and 9,10-dihydrophenanthrene
Authors: Collings Jonathan C , Batsanov Andrei S , Howard Judith AK , Marder Todd B
Published: May 2006

The 1:1 molecular complexes of octafluoronaphthalene (OFN) with fluorene (1) and with 9,10-dihydrophenanthrene (2) were prepared by cocrystallization of the components and characterized by single-crystal X-ray diffraction. The structure of 1 can be described as a mixed-stack or a laminar checkerboard motif of alternating OFN and fluorene molecules, whilst slanted mixed-stack, herringbone, and face-to-face heteromolecular dimer motifs can all be recognised in 2.Key words: single crystal, X-ray structure, π stacking, fluoroarene.
Synthesis of some new 1-aryl-4-formyl-3-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)pyrazoles using the Vilsmeier–Haack reaction — Isolation of the key intermediate 1-aryl-3-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)pyrazoles
Authors: Kumar Ajay , Prakash Om , Kinger Mayank , Singh Shiv P
Published: May 2006

Arylhydrazones of dehydroacetic acid (DHA) underwent Vilsmeier–Haack reaction to generate the corresponding 1-aryl-4-formyl-3-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)pyrazoles (1) with the pyrone moiety of the DHA remaining intact. However, when the reaction was performed using 1 equiv. of the reagent, compounds of 1-aryl-3-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)pyrazoles (2a–2f) were obtained, which underwent smooth conversion to 1-aryl-4-formyl-3-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)pyrazoles (1) on further treatment with another equivalent of the Vilsmeier–Haack reagent. This unreported observation suggests the intermediacy of 1-aryl-3-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)pyrazoles (2) in Vilsmeier–Haack reactions of hydrazones with a pyrone moiety. Several analogous compounds were also prepared using arylhydrazones of DHA.Key words: dehydroacetic acid, pyrazoles, Vilsmeier–Haack reaction, 3-acetyl-4-hydroxy-6-methyl-2H-pyran-2-one.