bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Material Transfer From a Soft Workpiece to a Hard Tool: Part I—Lump Growth Model
Authors: de Rooij M. B. , Schipper D. J.
Published: April 2007

An important mechanism reducing the lifetime of the deepdrawing tools is material transfer from the workpiece to the tool, resulting in the buildup of lumps on the tool surface. In this study, a lump growth model, based on transfer mechanisms observed in experiments, is developed. The development of the summit height distribution of the tool surface is calculated from the growth behavior of the individual lumps. Important parameters influencing material transfer are determined from the calculated summit height distributions. It follows that lump growth can be decreased and, under certain conditions prevented, by a higher (surface) hardness of the workpiece, a lower roughness of the tool surface, a lower nominal contact pressure, and a lower shear strength of the interface. These results are in general agreement with results obtained from experiments. Experimental results are presented in an accompanying paper (de Rooij and Schipper, 2000).
Static and Dynamic Characteristics of Aerostatic Circular Porous Thrust Bearings (Effect of the Shape of the Air Supply Area)
Authors: Yoshimoto S. , Kohno K.
Published: April 2007

Recently, graphite porous material has been used successfully in an aerostatic bearing. In actual bearing design, it is often necessary to reduce the thickness of porous material to make the bearing smaller. However, a reduction in thickness results in a reduction in the strength of the porous material. In particular, when the diameter of porous material is large, it is difficult to supply the air through the full pad area of porous material because it deforms. Therefore, in this paper, two types of air supply method (the annular groove supply and the hole supply) in a circular aerostatic porous thrust bearing are proposed to avoid the deflection of the bearing surface. The static and dynamic characteristics of aerostatic porous bearing with these air supply methods are investigated theoretically and experimentally. In addition, the effects of a surface restricted layer on the characteristics are clarified.
Influence of Inlet Conditions on the Thermohydrodynamic State of a Fully Circumferentially Grooved Journal Bearing
Authors: Keogh P. S. , Khonsari M. M.
Published: April 2007

A thermohydrodynamic (THD) analysis of a fully circumferentially grooved hydrodynamic bearing is presented. The pressure distribution is obtained using the short bearing approximation taking into account the viscosity variation in the radial and circumferential coordinates. The axial temperature variation is also included by an axial averaging technique, which incorporates the supply pressure and film entry temperature in the energy equation. It is found that the determination of the lubricant temperature at the entry to the film plays an important role in the overall temperature distribution in the bearing. A simplified approach for determining this temperature is presented. An extensive set of experimental results performed by Maki and Ezzat (1980, ASME J. Lubr. Technol., 102, pp. 8–14) is used for validation purposes. The results show that mixing in the inlet groove may cause the film entry temperature to be significantly different from the nominal supply temperature and hence have a significant influence on the bearing temperature.
Improvement of Web Spacing and Friction Characteristics by Two Types of Stationary Guides
Authors: Hashimoto Hiromu , Nakagawa Haruyasu
Published: April 2007

In this paper, two types of stationary guides are presented to improve the web spacing characteristics; hybrid hollow porous guide for maintaining the sufficient web spacing and grooved guide for removing the entrained air. In the hybrid hollow porous guide, the pressurized air is added to the lubrication air flow between web and guide from inside the guide. Then, the web spacing characteristics are improved by the hybrid effects of hydrodynamic pressure due to web movements and hydrostatic pressure due to pressurized added air through the guide. The relations between web spacing and web velocity are measured under various supply pressures. Moreover, the relations between web spacing and web tension are examined. The contactless optical sensor, which can measure the variation of the quantities of reflected light from the back surface of web according to the variation of web spacing, is used to obtain the web spacing under various conditions. In the grooved guide, the method for the estimation of web spacing by using the concept of equivalent spacing between web and guide is presented, and the web spacing is measured by the same experimental apparatus used in the case of hollow porous guide. From the calculated and measured results obtained, the effectiveness of two types of guides on the web spacing is clarified. Finally, based on the assumptions of Gaussian distributions of asperities, the simple relations to predict the friction coefficient between web and guide surfaces are formulated, and the variation of friction coefficient with velocity is shown for various values of web tension.
Stream Functions and Streamlines for Visualizing and Quantifying Side Flows in EHL of Elliptical Contacts
Authors: Hsiao Hsing-Sen S. , Hamrock Bernard J. , Tripp John H.
Published: April 2007

Three-dimensional stream functions for flows in elastohydrodynamically lubricated elliptical conjunctions are formulated. Closed-form and numerical solutions for the stream functions on special planes are obtained. Streamlines on these special planes are plotted to reveal the trajectories of the lubricant particles that pass by, pass through, or flow back from the Hertzian contact zone. Furthermore, a conceptual column stream function and column streamlines are introduced to present the three-dimensional flow in a two-dimensional manner. Thereby, the column streamlines can be plotted to visualize and quantify the flow rates of the lubricant that passes by or passes through the Hertzian zone.
Characterization of Pelletized MoS2 Powder Particle Detachment Process
Authors: Higgs C. Fred , Heshmat Hooshang
Published: April 2007

A recently postulated concept of friction between solids states that the process exhibits elements of quasi-hydrodynamic lubrication in which the wear particles shed from one or both surfaces form an interface layer acting as a lubricant. Pellets were formed by compacting MoS2 powder. A series of pellet-on disk tests were conducted to intentionally deposit wear particles on to a disk. The purpose of the tests are to aid in characterizing the particle detachment process of the pellet. This process consists of analyzing the transfer film, wear and frictional behavior of the pellet. This work also seeks to show that a MoS2 pellet can transfer a film capable of exhibiting tribological characteristics similar to those of liquid lubricants. For example, some tests were correlated with a dimensionless grouping of variables known as the Sommerfeld Number, to suggest the presence of quasi-hydrodynamic behavior in powder films. The pellet parameters that were analyzed were the particle size, compaction pressure and the effects of external loading during testing. Some of the conclusions arrived at were that smaller compaction pressures yield smaller friction coefficients and greater normal loads placed on pellets help to ensure the proper performance of the lubricating powder films. Data from the wear rate of the pellet and friction coefficient, in addition to the appearance of the wear particles were studied. An interesting feature of the pellet friction is that the longer the rest period in between test runs, the greater the friction values are at the resumption of testing. The present work is part of a continuing series to demonstrate that the process of so-called “dry” friction is not confined to the morphology of the interacting surfaces but that it is also a function of the shear and flow occurring at the interface.
EHD Analysis With Distributed Structural Inertia
Authors: Olson E. G. , Booker J. F.
Published: April 2007

An elastohydrodynamic lubrication model is presented for the coupled problem of a hydrodynamic lubricating fluid in an elastic structure that includes distributed structural inertia. The problem is formulated and the governing equations solved with the finite element method for an illustrative journal bearing subject to dynamic loading. Inertia effects are demonstrated through comparisons with an existing quasi-static model. While it is true that structural inertia can be neglected without significant loss of accuracy for many journal bearing applications, the new model presented does capture effects of distributed structural inertia where such effects are important and exhibits improvements over existing methods with respect to numerical stability.
Nanotribological and Nanomechanical Properties of Ultrathin Amorphous Carbon Films Synthesized by Radio Frequency Sputtering
Authors: Lu W. , Komvopoulos K.
Published: April 2007

The dependence of the nanotribological properties of ultrathin amorphous carbon (a-C) films, deposited on Si(100) substrates by radio frequency sputtering, on their nanomechanical properties was investigated using surface force microscopy. The thickness and nanohardness of the a-C films were found to be in the range of 7–95 nm and 9–44 GPa, respectively. Sharp conical diamond tips with a 90 deg included angle and radius of curvature of about 20 μm and 100 nm were used to perform friction and wear experiments, respectively. The effect of the substrate compliance on the nanomechanical and nanotribological properties of the a-C films is interpreted in terms of the indentation depth and the film thickness. The coefficient of friction and wear rate of the a-C films are related to their nanomechanical properties, thickness, and surface roughness. The dependence of the coefficient of friction on contact load and the dominant friction mechanisms of elastically and plastically deformed films are discussed in light of friction force and surface imaging results. High effective hardness-to-elastic modulus ratio and low surface roughness characterize high wear resistance a-C films. Below a critical load, the steady-state removal rate of the film material is insignificantly small, revealing a predominantly elastic behavior.
Dynamic Response of a Circular Tunnel Embedded in a Saturated Poroelastic Medium due to a Moving Load
Authors: Lu Jian-Fei , Jeng Dong-Sheng
Published: April 2007

Dynamic response of a circular tunnel embedded in a porous medium and subjected to a moving axisymmetric ring load is investigated in this paper. In this study, two scalar potentials and two vectorial potentials are introduced to represent the displacements for the solid skeleton and the pore fluid. Based on Biot’s theory and applying the Fourier transformation on time variable, a set of frequency domain governing equations for the potentials are obtained. Performing the Fourier transformation on the axial coordinate, closed-form general solutions for the potentials with arbitrary constants are obtained. Using the closed-form general solutions and boundary conditions along the tunnel surface, the arbitrary constants involved in the potentials are calculated. Representations for the displacements, the stresses and the pore pressure are derived in terms of the closed-form potentials. Analytical inversion of the Fourier transformation with respect to frequency and numerical inversion of the Fourier transformation with respect to the axial wave number lead to numerical solutions for the displacements, the stresses and the pore pressure in the porous medium. Numerical results demonstrate the soil response due to a high speed load is quite different from those due to a static load or a lower speed load. These differences become more pronounced when the velocity of moving load approaches the velocities of elastic waves of a porous medium.
Localized Vibration Isolation Strategy for Low-Frequency Excitations in Membrane Space Structures
Authors: Sakamoto Hiraku , Park K. C.
Published: April 2007

The present study explores both structural and controller design to attenuate vibration in large membrane space structures, especially due to low-frequency harmonic excitations. It is very difficult for membrane structures to suppress the low-frequency vibration induced by flexible support structures, because a lightly prestressed membrane has extremely low mode frequencies and little damping effect. The present study proposes the use of weblike perimeter cables around a membrane, and the application of simple and lightweight active controllers only along the web cables in order to isolate the membrane from vibration. This strategy successfully reduces the membrane vibration when the web-cable configuration is appropriately tailored. Both linear and nonlinear finite-element analyses exhibit a clear tradeoff between structural mass and control efficiency.
Suppression of Persistent Rotor Vibrations Using Adaptive Techniques
Authors: Matras Alex L. , Flowers George T. , Fuentes Robert , Balas Mark , Fausz Jerry
Published: April 2007

Recent work in the area of adaptive control has seen the development of techniques for the adaptive rejection of persistent disturbances for structural systems. They have been implemented and tested for large-scale structural systems, with promising results, but have not been widely applied to smaller-scale systems and devices. Rotor systems are subject to a variety of persistent disturbances (for example, due to mass imbalance, blade-pass effects) that occur at the rotor running speed or multiples of the running speed. The frequencies of such disturbance forces are generally known, but their magnitudes tend to vary over time. Adaptive techniques to counter the effects of such disturbances would appear to be a promising strategy in this regard. In order to assess the effectiveness of adaptive disturbance rejection for rotor applications and identify issues associated with implementation, an adaptive disturbance rejection control is developed, implemented, and tested for a magnetic-bearing-supported rotor system. Some conclusions and insights concerning the application of this method to rotor system vibration suppression are presented and discussed.
Parameter Reconstruction Based on Sensitivity Vector Fields
Authors: Epureanu Bogdan I. , Hashmi Ali
Published: April 2007

A novel approach to determine very accurately multiple parameter variations by exploiting the geometric shape of dynamic attractors in state space is presented. The approach is based on the analysis of sensitivity vector fields. These sensitivity vector fields describe changes in the state space attractor of the dynamics and system behavior when parameter variations occur. Distributed throughout the attractor in state space, these fields form a collection of snapshots for known parameter changes. Proper orthogonal decomposition of the parameter space is then employed to distinguish multiple simultaneous parametric variations. The parametric changes are reconstructed by analyzing the deformation of attractors which are characterized by means of the sensitivity vector fields. A set of basis functions in the vector space formed by the sensitivity fields is obtained and is used to successfully identify test cases involving multiple simultaneous parametric variations. The method presented is shown to be robust over a wide range of parameter variations and to perform well in the presence of noise. One of the main applications of the proposed technique is detecting multiple simultaneous damage in vibration-based structural health monitoring.
Detection of a Rotor Crack Using a Harmonic Excitation and Nonlinear Vibration Analysis
Authors: Ishida Yukio , Inoue Tsuyoshi
Published: April 2007

Detection of a rotor crack based on the nonlinear vibration diagnosis using harmonic excitation force is investigated. The open-close mechanism of crack is firstly modeled by a piecewise linear function. In addition, another approximation crack model using a power series function that is convenient for the theoretical analysis is used. When the power series function crack model is used, the equations of motion of a cracked rotor have linear and nonlinear parametric terms. In this paper, a harmonic excitation force is applied to the cracked rotor and its excitation frequency is swept, and the nonlinear resonances due to crack are investigated. The occurrence of various types of nonlinear resonances due to crack are clarified, and types of these resonances, their resonance points, and dominant frequency component of these resonances are clarified numerically and experimentally. Furthermore, nonlinear theoretical analyses are performed for these nonlinear resonances, and it is clarified that the amplitudes of these nonlinear resonances depend on the nonlinear parametric characteristics of rotor crack. These results enable us to detect a rotor crack without stopping the system during on-line operation.
The After-Hours Mutant Reveals a Role for Fbxl3 in Determining Mammalian Circadian Period
Authors: Godinho Sofia I. H. , Maywood Elizabeth S. , Shaw Linda , Tucci Valter , Barnard Alun R. , Busino Luca , Pagano Michele , Kendall Rachel , Quwailid Mohamed M. , Romero M. Rosario , O'Neill John , Chesham Johanna E. , Brooker Debra , Lalanne Zuzanna , Hastings Michael H. , Nolan Patrick M.
Published: April 2007

By screening
N
-ethyl-
N
-nitrosourea–mutagenized animals for alterations in rhythms of wheel-running activity, we identified a mouse mutation, after hours (
Afh
). The mutation, a Cys
358
Ser substitution in Fbxl3, an F-box protein with leucine-rich repeats, results in long free-running rhythms of about 27 hours in homozygotes. Circadian transcriptional and translational oscillations are attenuated in
Afh
mice. The
Afh
allele significantly affected Per2 expression and delayed the rate of Cry protein degradation in Per2::Luciferase tissue slices. Our in vivo and in vitro studies reveal a central role for Fbxl3 in mammalian circadian timekeeping.
MET
Amplification Leads to Gefitinib Resistance in Lung Cancer by Activating ERBB3 Signaling
Authors: Engelman Jeffrey A. , Zejnullahu Kreshnik , Mitsudomi Tetsuya , Song Youngchul , Hyland Courtney , Park Joon Oh , Lindeman Neal , Gale Christopher-Michael , Zhao Xiaojun , Christensen James , Kosaka Takayuki , Holmes Alison J. , Rogers Andrew M. , Cappuzzo Federico , Mok Tony , Lee Charles , Johnson Bruce E. , Cantley Lewis C. , Jänne Pasi A.
Published: April 2007

The epidermal growth factor receptor (EGFR) kinase inhibitors gefitinib and erlotinib are effective treatments for lung cancers with
EGFR
activating mutations, but these tumors invariably develop drug resistance. Here, we describe a gefitinib-sensitive lung cancer cell line that developed resistance to gefitinib as a result of focal amplification of the
MET
proto-oncogene. inhibition of MET signaling in these cells restored their sensitivity to gefitinib.
MET
amplification was detected in 4 of 18 (22%) lung cancer specimens that had developed resistance to gefitinib or erlotinib. We find that amplification of
MET
causes gefitinib resistance by driving ERBB3 (HER3)–dependent activation of PI3K, a pathway thought to be specific to EGFR/ERBB family receptors. Thus, we propose that
MET
amplification may promote drug resistance in other ERBB-driven cancers as well.
Genome-Wide Association Analysis Identifies Loci for Type 2 Diabetes and Triglyceride Levels
Authors: Saxena Richa , Voight Benjamin F. , Lyssenko Valeriya , Burtt Noël P. , de Bakker Paul I. W. , Chen Hong , Roix Jeffrey J. , Kathiresan Sekar , Hirschhorn Joel N. , Daly Mark J. , Hughes Thomas E. , Groop Leif , Altshuler David , Almgren Peter , Florez Jose C. , Meyer Joanne , Ardlie Kristin , Bengtsson Boström Kristina , Isomaa Bo , Lettre Guillaume , Lindblad Ulf , Lyon Helen N. , Melander Olle , Newton-Cheh Christopher , Nilsson Peter , Orho-Melander Marju , Råstam Lennart , Speliotes Elizabeth K. , Taskinen Marja-Riitta , Tuomi Tiinamaija , Guiducci Candace , Berglund Anna , Carlson Joyce , Gianniny Lauren , Hackett Rachel , Hall Liselotte , Holmkvist Johan , Laurila Esa , Sjögren Marketa , Sterner Maria , Surti Aarti , Svensson Margareta , Svensson Malin , Tewhey Ryan , Blumenstiel Brendan , Parkin Melissa , DeFelice Matthew , Barry Rachel , Brodeur Wendy , Camarata Jody , Chia Nancy , Fava Mary , Gibbons John , Handsaker Bob , Healy Claire , Nguyen Kieu , Gates Casey , Sougnez Carrie , Gage Diane , Nizzari Marcia , Gabriel Stacey B. , Chirn Gung-Wei , Ma Qicheng , Parikh Hemang , Richardson Delwood , Ricke Darrell , Purcell Shaun
Published: April 2007

New strategies for prevention and treatment of type 2 diabetes (T2D) require improved insight into disease etiology. We analyzed 386,731 common single-nucleotide polymorphisms (SNPs) in 1464 patients with T2D and 1467 matched controls, each characterized for measures of glucose metabolism, lipids, obesity, and blood pressure. With collaborators (FUSION and WTCCC/UKT2D), we identified and confirmed three loci associated with T2D—in a noncoding region near
CDKN2A
and
CDKN2B
, in an intron of
IGF2BP2
, and an intron of
CDKAL1
—and replicated associations near
HHEX
and in
SLC30A8
found by a recent whole-genome association study. We identified and confirmed association of a SNP in an intron of glucokinase regulatory protein (GCKR) with serum triglycerides. The discovery of associated variants in unsuspected genes and outside coding regions illustrates the ability of genome-wide association studies to provide potentially important clues to the pathogenesis of common diseases.
Replication of Genome-Wide Association Signals in UK Samples Reveals Risk Loci for Type 2 Diabetes
Authors: Zeggini Eleftheria , Weedon Michael N. , Lindgren Cecilia M. , Frayling Timothy M. , Elliott Katherine S. , Lango Hana , Timpson Nicholas J. , Perry John R. B. , Rayner Nigel W. , Freathy Rachel M. , Barrett Jeffrey C. , Shields Beverley , Morris Andrew P. , Ellard Sian , Groves Christopher J. , Harries Lorna W. , Marchini Jonathan L. , Owen Katharine R. , Knight Beatrice , Cardon Lon R. , Walker Mark , Hitman Graham A. , Morris Andrew D. , Doney Alex S. F. , McCarthy Mark I. , Hattersley Andrew T.
Published: April 2007

The molecular mechanisms involved in the development of type 2 diabetes are poorly understood. Starting from genome-wide genotype data for 1924 diabetic cases and 2938 population controls generated by the Wellcome Trust Case Control Consortium, we set out to detect replicated diabetes association signals through analysis of 3757 additional cases and 5346 controls and by integration of our findings with equivalent data from other international consortia. We detected diabetes susceptibility loci in and around the genes
CDKAL1
,
CDKN2A/CDKN2B
, and
IGF2BP2
and confirmed the recently described associations at
HHEX/IDE
and
SLC30A8
. Our findings provide insight into the genetic architecture of type 2 diabetes, emphasizing the contribution of multiple variants of modest effect. The regions identified underscore the importance of pathways influencing pancreatic beta cell development and function in the etiology of type 2 diabetes.
Do-not-resuscitate decision: the attitudes of medical and non-medical students
Authors: Sham C O , Cheng Y W , Ho K W , Lai P H , Lo L W , Wan H L , Wong C Y , Yeung Y N , Yuen S H , Wong A Y C
Published: April 2007

Objectives:To study the attitudes of both medical and non-medical students towards the do-not-resuscitate (DNR) decision in a university in Hong Kong, and the factors affecting their attitudes.

Methods:A questionnaire-based survey conducted in the campus of a university in Hong Kong. Preferences and priorities of participants on cardiopulmonary resuscitation in various situations and case scenarios, experience of death and dying, prior knowledge of DNR and basic demographic data were evaluated.

Results:A total of 766 students participated in the study. There were statistically significant differences in their DNR decisions in various situations between medical and non-medical students, clinical and preclinical students, and between students who had previously experienced death and dying and those who had not. A prior knowledge of DNR significantly affected DNR decision, although 66.4% of non-medical students and 18.7% of medical students had never heard of DNR. 74% of participants from both medical and non-medical fields considered the patient’s own wish as the most important factor that the healthcare team should consider when making DNR decisions. Family wishes might not be decisive on the choice of DNR.

Conclusions:Students in medical and non-medical fields held different views on DNR. A majority of participants considered the patient’s own wish as most important in DNR decisions. Family wishes were considered less important than the patient’s own wishes.
The absence of sadness: darker reflections on the doctor–patient relationship
Authors: Berry Philip A
Published: April 2007

Recognising a diminution in his emotional response to patients’ deaths, the author analyses in detail his internal reactions in an attempt to understand what he believes is a common phenomenon among doctors. He identifies factors that may erode the connection between patient and physician: an instinct to separate oneself from another’s suffering, professional unease in the case of therapeutic failure, the atrophying effect of perceived hopelessness, insincerities in the establishment of the initial relationship, and an inability to imbue the sedated or unconscious patient with human qualities. He concludes that recognition of these negative influences, without necessarily changing behaviours that are natural, may be a first step towards protecting doctors against what might be an otherwise insidious process of dehumanisation.
“Why aren’t you doing what we want?” Cultivating collegiality and communication between specialist and generalist physicians and residents
Authors: Rentmeester Christy A
Published: April 2007

Developing residents’ communication skills has been a goal of residency training programmes since the Accreditation Council for Graduate Medical Education codified it as a core competency. In this article, a case that features problematic communication between a generalist and specialist physician is drawn upon, and it is suggested how their communication might become open and effective through a practice of reason exchange. This is a practice of giving reasons, listening to reasons given by others, evaluating reasons and deciding which particulars of situations constitute reasons to act and reasons how to act. Drawing on recent literature in teaching communication to radiology residents, it is proposed that practices of reason exchange are part of the skill set generally referred to as “negotiation skills” that should be cultivated in all residents. Particularly, in cases in which generalist and specialist physicians disagree about the reasons to do something, not do something or do something this way or that way, how well physicians are trained to practice reason exchange depends on whether they can communicate effectively and negotiate disagreement collegially.
cis-Cytokinins that predominate inPisum sativumduring early embryogenesis will accelerate embryo growth in vitro
Authors: Quesnelle Pauline E. , Emery R.J. Neil
Published: April 2007

Correlative data from monocots suggest that cytokinin (CK) regulates seed development. The involvement of CKs in seed growth was investigated using pea, a eudicot with an unknown CK profile, as a model system. CK profiles were measured by liquid chromatography – tandem mass spectrometry against major stages of embryogenesis, which were documented histologically. Like other grain legumes, CK levels of developing pea seeds fluctuated through development and had mainly nucleotide and riboside forms. Among the 11 CKs detected, cis-isomers (cis-[9R]Z (zeatin riboside), and cis-[9RMP]Z (zeatin riboside 5′ monophosphate)), along with their isopentenyl precursors, were the major forms during pea embryogenesis, whereas corresponding trans-isomers appeared as minor constituents. Highest CK concentrations occurred at the heart-shape stage, when there are high rates of cell division and sugar metabolism. To assess the significance of high CK concentrations observed at the heart-shape stage, a bioassay was developed wherein heart-shaped embryos were excised and cultured on medium containing either cis-[9R]Z, trans-[9R]Z, or kinetin. Growth of cultured heart-shaped embryo explants was significantly augmented by all exogenous CKs relative to controls that were not supplemented with CK. Moreover, at concentrations equivalent to those experienced by an embryo in vivo, cis-[9R]Z was active in enhancing the growth of cultured pea embryos to an extent equal to that of trans-[9R]Z. Overall, the results endorse a growth-promoting role for cis-CKs during seed development.
Inflorescence development in two tomato species
Authors: Welty N. , Radovich C. , Meulia T. , van der Knaap E.
Published: April 2007

The inflorescence of tomato has been characterized as either a cyme or raceme. Cymose inflorescences are determinate, whereas racemose inflorescences are indeterminate. In this study, we addressed the discrepancy in inflorescence architecture by analyzing the morphology of a wild relative of tomato Solanum pimpinellifolium L. and four domesticated Solanum lycopersicum L. lines. Careful observation of developing inflorescences of both species showed a bifurcation of the meristem into a determinate floral and an indeterminate inflorescence meristem. Interestingly, higher fruit carpel number was associated with delayed floral development, which might give the impression of determinate growth in some of the lines. Nevertheless, our results demonstrated that tomato inflorescences are indeterminate in nature regardless of the line studied. Floral buds were formed concomitantly with the development of the inflorescence meristem and not on the flanks of the peduncle, a characteristic of racemose growth. Thus, tomato inflorescences should be classified as a cyme with the note that the inflorescence meristem does not terminate into a flower and, in fact, maintains indeterminacy. In addition, S. pimpinellifolium produced many more flowers in a highly regular manner when compared with the cultivated types. This demonstrated the usefulness of wild relatives of tomato as a tool to further understand flower and fruit development in this crop species.
Metal Stable Isotopes in Paleoceanography
Authors: Anbar Ariel D. , Rouxel Olivier
Published: April 2007

Considered esoteric only a few years ago, research into the stable isotope geochemistry of transition metals is moving into the geoscience mainstream. Although initial attention focused on the potential use of some of these nontraditional isotope systems as biosignatures, they are now emerging as powerful paleoceanographic proxies. In particular, the Fe and Mo isotope systems are providing information about changes in oxygenation and metal cycling in ancient oceans. Zn, Cu, Tl, and a number of other metals and metalloids also show promise. Here we review the basis of stable isotope fractionation as it applies to these elements, analytical considerations, and the current status and future prospects of this rapidly developing research area.
The Arctic Forest of the Middle Eocene
Authors: Jahren A. Hope
Published: April 2007

Lush forests, dominated by deciduous conifers, existed well north of the Arctic Circle during the middle Eocene (∼45 Ma). The Fossil Forest site, located on Axel Heiberg Island, Canada, has yielded a particularly rich assemblage of plant macro- and microfossils, as well as paleosols—all exquisitely preserved. Methods ranging from classical paleobotany, to stable-isotope geochemistry, have been applied to materials excavated from the Fossil Forest and have revealed layers of diverse conifer forests with a rich angiosperm understory that successfully endured three months of continuous light and three months of continuous darkness. Paleoenvironmental reconstructions suggest a warm, ice-free environment, with high growing-season-relative humidity, and high rates of soil methanogenesis. Methods to evaluate intraseasonal variability highlight the switchover from stored to actively fixed carbon during the short annual growing season.
GaAs Heteroepitaxy on SiGe-on-Insulator Using Ge Condensation and Migration Enhanced Epitaxy
Authors: Oh Hoon-Jung , Choi Kyu Jin , Loh Wei Yip , Htoo Thwin , Chua Soo Jin , Cho Byung Jin
Published: April 2007

A novel fabrication technique to grow device quality GaAs on Si substrate is proposed using thin graded SiGe-on-insulator (SGOI) substrate. Combination of low-temperature GaAs molecular beam epitaxy (MBE) growth technique, low-temperature GaAs migration enhanced epitaxy (MEE) technique, and modified two-step Ge condensation technique has demonstrated successful growth of 10-nm GaAs layer grown on a tensile strained 42-nm graded SGOI layer.
Effective Capture Cross-Sections of Traps in High-k Gate Dielectrics
Authors: Song Liyang , Wang Xiewen , Guo Dechao , Ma T.P.
Published: April 2007

We report an experimental study of captures cross-sections of traps in some ultra-thin high-k gate dielectrics. We focus on a surprising finding that the effective capture cross-sections seemed to be extraordinarily small (between 10e-22 and 10e-19cm2) compared. We arrived at the conclusion that the low values of the effective capture cross-section arise from significant de-trapping, which is not accounted for in the trapping models used in extracting the trap cross-sections. The results of this study point out that it is important to consider the film thickness and leakage current when extracting capture cross-sections in ultra thin gate dielectrics.
Thermodynamic Properties of Trace Water Vapor in High Purity Hydrogen Bromide used for Semiconductor Processing
Authors: Yao Jianlong , Olsen Eric , Raynor Mark
Published: April 2007

The distribution of water between gas and liquid phases was investigated for high purity HBr cylinders, and standard enthalpy of vaporization and Henry's law constant for trace amount of water in HBr were extracted. In the 3-32 {degree sign} C temperature range, the water vapor concentration in the gas phase of a cylinder is a function of cylinder temperature and the enthalpies of vaporization of water and HBr. The standard enthalpy of vaporization for trace amount of H2O in HBr was found to be 58.5 kJ/mol. The temperature dependent Henry's law constant can be expressed as: ln K(T) = -7031.44/T + 22.38. Using the thermodynamic parameters found, water vapor concentration measured for gas-phase HBr from cylinders at various temperatures can be normalized to corresponding levels at a chosen standard temperature, e.g. 21{degree sign}C. This is very important in establishing meaningful water vapor specifications, and trustworthy quality control protocols for high purity HBr gas.
Reduced Parameter Fluctuation with Laser and Flash Lamp Anneal for 65nm Volume Production
Authors: Feudel Thomas , Bayha B , Burbach G , Gerhardt M , Herrmann L , Herden M , Mantei T , Ehrichs E , Greenlaw M , Horstmann Manfred
Published: April 2007

Process parameter fluctuations have a strong impact on functionality and performance of CMOS logic circuits and memory cells. Tight control of transistor gate length and final anneal temperature are equally important. We have developed a strategy to monitor these fluctuations which takes into account the full complexity of advanced microprocessors with large cache cell areas. This paper shows that reducing the anneal temperature reduces the parameter fluctuations. Transistor performance degradation at reduced temperatures can be compensated by using advanced annealing techniques like Laser or Flash lamp anneal. These techniques do not result in additional parameter fluctuation.
Chemical Vapor Deposition Epitaxy of Silicon and Silicon-Carbon Alloys at High Rates and Low Temperatures using Neopentasilane
Authors: Sturm James C. , Chung Keith H. , Yao N. , Sanchez E. , Singh K. K. K. , Carlson D. , Kuppurao S.
Published: April 2007

The silicon precursor neopentasilane is used to grow epitaxial silicon at high growth rates from 550 to 700 oC, with rates over 100 nm/min achieved at 600 oC. The layer quality as observed by TEM and the performance of FET's made in these films is high. Neopentasilane has also been used to grow dilute strained Si1-yCy alloys on silicon with very high growth rates. For carbon levels on the order of 2%, strained layers were grown at rates over 40 nm/min.
NiSi Roughness on Embedded SiGe
Authors: Kwon O Sung , Kwon Oh-Jung , Han Jin-Ping , Utomo Henry
Published: April 2007

In this paper, the effects of Si capping and of Ge pre- amorphization (PAI) on embedded SiGe (eSiGe) and its influence on NiSi interface roughness are investigated. TEM and EDX analysis show that NiSi on eSiGe produces a very rough interface and a void-like Ni deficient area. In-situ Si capping of about 20nm thickness can effectively remove the void-like Ni deficient area on eSiGe, but it still shows the rough interface. Rs and Jlkg measurements do not clearly show the difference compared to non Si capping. However Si capping combined with Ge PAI can remove the Ni deficient area and produce a smooth interface, tightened Rs distribution, and about 100 times reduced junction leakage current. So Si capping combined with Ge PAI is very beneficial for NiSi roughness improvement on eSiGe.
Dielectric and Electrode Thin Films for Stack-Cell Structured DRAM Capacitors with sub 50-nm Design Rules
Authors: Kim Seong Keun , Lee Sang Woon , Seo Minha , Han Jeong Hwan , Lee Sang Young , Hwang Cheol Seong
Published: April 2007

TiO2 thin films with high dielectric constants (83 - 100) were grown on sputtered and atomic-layer-deposited (ALD) Ru electrode at a growth temperature of 250oC using the atomic- layer-deposition method. The as-deposited films were crystallized with rutile structure. Further improvements in the leakage current characteristics are achieved by proper doping of Al and Hf, thereby an equivalent oxide thickness (tox) ~ 0.6 nm with small enough leakage current density (1 x 10-7 A/cm2 at 0.8V) was achieved. These good properties are also realized from 3D structured hole-type capacitors. The rutile structured TiO2 films were also obtained from Ru electrode which is deposited by an ALD process using a newly developed noble precursor. In addition, it was confirmed that the Ru metal film step coverage on the capacitor hole structure with an aspect ratio of 17 is > 90 %. The thermal stability of the Ru electrode on severe 3D holes was improved with the adoption of hydrogen plasma process.
The Physical Origins of Fast and Slow Components in NBTI Degradation for p-MOS Transistors with SiON Gate Dielectric
Authors: Li Ming-Fu , Shen Chen , Yang T , Chen Gan , Huang Daming
Published: April 2007

We summarize our recent investigation on the NBTI degradation in p-MOSFETs with SiON gate dielectric. (1)For the slow NBTI component, we show evidence that the degradation and recovery is due to interface trap Nit generation and passivation. Nit measured by conventional CP and DCIV methods is underestimated due to passivation under measurement; (2) Due to the degradation during initial threshold voltage measurement, the existing (slow) on-the-fly measurement distorts (overestimates) the slope and induces a kink at early stress time in the Log-Log curve of static NBTI degradation time evolution. A fast on-the-fly method is developed to overcome this problem. (3) An ultra-fast (100ns) transient pulse Vth measurement method is developed to avoid the recovery of fast NBTI component during measurement, and is compared to the fast on-the-fly measurement results with excellent agreement. (4) Our experiments show that there are two NBTI components, fast and slow. The fast component measured by ultra-fast pulsed method is mainly due to trapping de-trapping of oxide charge. All experimental results can be well explained in this scheme with very good quantitative agreement between the modeling and the experimental data.
Bias Temperature Instability Characterization of Advanced Gate Stacks
Authors: Fujieda Shinji , Terai Masayuki , Saitoh Motofumi , Toda Akio , Miura Yoshinao , Liu Ziyuan , Teraoka Yuden , Yoshigoe Akitaka , Wilde Markus , Fukutani Katsuyuki
Published: April 2007

We performed a physical and electrical characterization of the defects that would cause negative and positive bias temperature instability (NBTI, PBTI) in gate stacks that use SiO2, plasma-nitrided SiO2, HfSiON, and HfSiON with Ni- silicide electrodes. The characterization shows that the influence of impurities, damages and mechanical stress, derived from the newly incorporated materials and process technologies on the insulator bulk and insulator/Si interface must be suppressed to cope with the problems of NBTI and PBTI in the advanced gate stacks.
Microscopic Mechanism of Silicon Thermal Oxdation Process
Authors: Kageshima Hiroyuki , Uematsu Masashi , Akiyama Toru , Ito Tomonori
Published: April 2007

Our recent achievement for the scheme on microscopic mechanism of silicon thermal oxidation processes is shown. In our scheme, the silicon thermal oxidation processes consists of three processes; (a) oxygen diffusion through the oxide, (b) oxygen reaction at the interface, and (c) deformation of the interfacial oxide. The third process, deformation, is not included in the classical Deal-Grove scheme, but our results suggest that the so-called reaction limited regime of the Deal-Grove theory is governed by this deformation. Both theoretical and experimental studies are described in support of the new scheme.
A New Kinetic Equation for Thermal Oxidation of Silicon Replacing the Deal-Grove Equation
Authors: Watanabe Takanobu , Ohdomari Iwao
Published: April 2007

A newly formulated kinetic theory for thermal oxidation of silicon is reviewed. The new theory does not involve the rate- limiting step of the interfacial oxidation reaction, instead it is supposed that the diffusivity is suppressed in a strained oxide region near the SiO2/Si interface. The expression of the parabolic constant is the same as that of the Deal-Grove model, while the linear constant makes a clear distinction with the model. The estimated thickness using the new expression is close to 1 nm, which compares well with the thickness of the structural transition layer. The origin of the deviation from the linear-parabolic relationship observed at initial oxidation stages can be explained by the enhanced diffusion hypothesis, which is opposite conclusion to the Deal- Grove theory.
CON-TACT® Planarization Process of Spin-on Dielectrics for Device Fabrication
Authors: Shih Wu-Sheng , Yota J. , Itchhaporia Ketan
Published: April 2007

Planarization has become a necessity for fabricating devices, large and small. Without planarization, a limited number of layers of interconnects or device structures can be successfully fabricated. CON TACT® planarization technology has been used to planarize various spin-on dielectric materials to provide both local and global planarity. Materials such as epoxies, anti-reflective coatings, photoresists, spin-on glass, CycloteneTM, polybenzoxazole, and polyimide have been successfully planarized with up to more than 98% topography reduction. Consequently, the overburden variation was reduced. The planarization performance obtained promises great potential for this technology to provide more consistent, more reliable and otherwise improved device performance for more sophisticated device designs with higher yield.
High-Mobility and Low-Vth Metal Gate CMOSFETs with Ultra-Thin HfSiON Gate Dielectrics Using TaSiN/TaSix Stacked Electrode and Selective Substrate Fluorine Implantation
Authors: Inumiya Seiji , Matsuki Takeo , Aoyama Takayuki , Nara Yasuo
Published: April 2007

A simple fabrication process has been demonstrated for metal/high-k gate-first CMOS with a single work-function control layer of TaSiN/TaSix accompanied with selective substrate F implantation. Sub-1nm EOT HfSiON gate dielectrics with high-mobility were used, having been subjected to successful suppression of interfacial layer growth during processes. Sufficiently low Vth of 0.39 V and -0.38 V for low- standby-power (LSTP) applications were obtained for nFET and pFET, respectively. A high electron mobility of 213 cm2/Vs at Eeff=1.0 MV/cm was maintained, due to the double nitridation barrier effects of TaSiN/TaSix. Hole mobility enhancement and NBTI improvement were also obtained by F implantation, even in metal gate pFETs.
Embedding Device Solutions in Engineered Substrates
Authors: Mazure Carlos
Published: April 2007

A review of the advances in Smart Cut engineered substrates and the impact on device performance and IC design will be given. while primarily focusing on CMOS applications, the application of substrate engineering to other fields like photonics, power ICs, nano-patterning while also be reviewed.
Impact of Metal Silicide Layout Covering Source/Drain Diffusions on Parasitic Resistance of Triple-Gate SOI MOSFET
Authors: Yoshimoto Kazuhisa , Omura Y. , Wakabayashi Hitoshi
Published: April 2007

This paper describes an impact of silicide layout in the S/D region on parasitic resistance of the multiple-fin triple-gate (TG) SOI MOSFET. For devices with narrow S/D region, it is demonstrated that P-shape layout with a thin silicide film results in the lowest parasitic resistance. On the other hand, for devices with wide S/D region, it is shown that a deep 'localized-silicide' layout results in the lowest parasitic resistance. The silicide/Si contact area should be as large as possible. It is also strongly suggested that a new technique is needed to reduce the parasitic resistance in sub-10-nm channel TG SOI MOSFET's.
Fabrication and Power-Management Demonstration of Four-Terminal FinFETs
Authors: Endo Kazuhiko , Liu Yongxum , Masahara Meishoku , Matsukawa Takashi , O'uchi Shin'Ichi , Suzuki Eiichi
Published: April 2007

A high-aspect-ratio and damage-free vertical ultrathin channel (UTC) for a vertical-type double-gate (DG) MOSFET has been fabricated by using low-energy neutral-beam (NBE) etching. Also, dynamically power-controllable CMOS technology has been investigated using separated-gate four-terminal (4T) FinFETs. We demonstrate that the power consumption of the CMOS inverter can dynamically be controlled using the 4T-FinFET.
The C Shape Behavior of the Floating Body Effect in Function of Temperature in PD SOI nMOSFETs
Authors: Agopian Paula G. , Martino Joao Antonio A. , Simoen Eddy , Claeys Cor
Published: April 2007

The temperature influence on the gate induced floating body effect in partially depleted (PD) Silicon-on-Insulator (SOI) nMOSFETs is investigated, through experimental results and two- dimensional numerical simulations. A C shape behavior of the transconductance second peak as a function of temperature is observed, due to the competition between two effects: the generation-recombination process and the effective electric field mobility degradation.
Complementary Single-Crystal Silicon TFTs on Plastic
Authors: Yuan Hao-Chih , Ma Zhenqiang , Ritz Clark , Savage Donald , Lagally Max , Celler G.
Published: April 2007

This paper reports the first demonstration of both n- and p-type thin-film transistors (TFTs) on flexible plastic substrate using single-crystal Si (110) surface-oriented nanomembrane as active layer. The Si (110) nanomembrane of 190-nm thickness is derived from UNIBOND® silicon-on-insulator (SOI) fabricated by hybrid orientation technology (HOT) and transferred to flexible plastic substrate followed by a low-temperature (< 120 ºC) device process. Good device performance has been achieved under so far not-perfected device processing conditions, which includes field-effect mobility of around 95 and 45 cm2/V-sec on the linear region for the n- and p-type Si (110) TFTs, respectively, and device current ON/OFF ratio better than 10000 for both types of TFTs.