bluuebunny/crossref_metadata_2025 huggingface dataset:
A Calcium and Free Fatty Acid-Modulated Protein Kinase as Putative Effector of the Fusicoccin 14-3-3 Receptor
Authors: Van der Hoeven PCJ. , Siderius M. , Korthout HAAJ. , Drabkin A. V. , De Boer A. H.
Published: July 2002

A protein kinase that is activated by calcium and cis-unsaturated fatty acids has been characterized from oat (Avena sativa L.) root plasma membranes. The kinase phosphorylates a synthetic peptide with a motif (-R-T-L-S-) that can be phosphorylated by both protein kinase C (PKC) and calcium-dependent protein kinase (CDPK)-type kinases. Calphostin C and chelerythrine, two PKC inhibitors, completely inhibited the kinase activity with values of inhibitor concentration for 50% inhibition of 0.7 and 30 [mu]M, respectively. At low Ca2+ concentrations cis-unsaturated fatty acids (linolenic acid, linoleic acid, arachidonic acid, and oleic acid) stimulated the kinase activity almost 10-fold. The two inhibitors of the kinase, calphostin C and chelerythrin, strongly reduced the fusicoccin (FC)-induced H+ extrusion, and the activators of the kinase, the cis-unsaturated fatty acids, prevented [3H]FC binding to the FC 14–3–3 receptor. CDPK antibodies cross-reacted with a 43-kD band in the plasma membrane and in a purified FC receptor fraction. A polypeptide with the same apparent molecular mass was recognized by a synthetic peptide that had a sequence homologous to the annexin-like domain from barley 14–3–3. The possibility of the involvement of a kinase, with properties from both CDPK and PKC, and a phospholipase A2 in the FC signal transduction pathway is discussed.
Lipoxygenase Gene Expression in the Tobacco-Phytophthora parasitica nicotianae Interaction
Authors: Veronesi C. , Rickauer M. , Fournier J. , Pouenat M. L. , Esquerre-Tugaye M. T.
Published: July 2002

A recently isolated cDNA clone of tobacco (Nicotiana tabacum L.) lipoxygenase (LOX) was used to study LOX gene expression in tobacco cell-suspension cultures and intact plants in response to infection with Phytophthora parasitica nicotianae (Ppn). Southern blot analysis of tobacco DNA indicated that only a small number of LOX genes hybridize to this probe. These genes were not constitutively expressed to a detectable level in control cells and healthy plants. In contrast, a rapid and transient accumulation of transcripts occurred in cells and plants after treatment with elicitor and inoculation with zoospores of Ppn, respectively. In cell cultures LOX gene expression could also be induced by linolenic acid, a LOX substrate, and by methyl jasmonate, one of the products derived from the action of LOX on linolenic acid. In the infection assays, LOX gene expression and enzyme activity were observed earlier when the plants carried a resistance gene against the race of Ppn used for inoculation. The differential expression of LOX during the race-cultivar-specific interaction between tobacco and Ppn, as well as its regulation by elicitors and jasmonate, suggest a role of LOX in plant resistance and establishment of the defense status against this pathogen.
Regulation of Sesquiterpene Cyclase Gene Expression (Characterization of an Elicitor- and Pathogen-Inducible Promoter)
Authors: Yin S. , Mei L. , Newman J. , Back K. , Chappell J.
Published: July 2002

The promoter for a tobacco (Nicotiana tabacum) sesquiterpene cyclase gene, a key regulatory step in sesquiterpene phytoalexin biosynthesis, has been analyzed. The EAS4 promoter was fused to the β-glucuronidase (GUS) reporter gene, and the temporal and spatial expression patterns of GUS activity were examined in stably transformed plants and in transient expression assays using electroporated protoplasts of tobacco. No GUS activity was observed in any tissues under normal growth conditions. A low level of GUS activity was detected in wounded leaf, root, and stem tissues, whereas a much higher level was observed when these tissues were challenged with elicitors or microbial pathogens. The GUS expression pattern directed by the EAS4 promoter was identical to the induction patterns observed for the endogenous sesquiterpene cyclase genes. Neither exogenous salicylic acid nor methyl jasmonate induced GUS expression; and H2O2 induced GUS expression to only a limited extent. Although the EAS4 promoter contains cis-sequences resembling previously identified transcriptional control motifs, other cis-sequences important for quantitative and qualitative gene expression were identified by deletion and gain-of-function analyses. The EAS4 promoter differs from previously described pathogen-/elicitor-inducible promoters because it only supports inducible gene expression and directs unique spatial expression patterns.
A Calcium-Selective Channel from Root-Tip Endomembranes of Garden Cress1
Authors: Klüsener Birgit , Weiler Elmar W.
Published: July 2002

A Ca2+ channel from root-tip endomembranes of garden cress (Lepidium sativum L.) (LCC1) was characterized using the planar lipid-bilayer technique. Investigation of single-channel recordings revealed that LCC1 is voltage gated and strongly rectifying. In symmetrical 50 mm CaCl2 solutions, the single-channel conductance was 24 picosiemens. LCC1 showed a moderate selectivity for Ca2+ over K+ (9.4:1) and was permeable for a range of divalent cations (Ca2+, Ba2+, and Sr2+). In contrast to Bryonia dioica Ca2+ channel 1, a Ca2+-selective channel from the endoplasmic reticulum of touch-sensitive tendrils, LCC1 showed no bursting channel activity and had a low open probability and mean open time (2.83 ms at 50 mV). Inhibitor studies demonstrated that LCC1 is blocked by micromolar concentrations of erythrosin B (inhibitor concentration for 50% inhibition [IC50] = 1.8 μm) and the trivalent cations La3+(IC50 = 5 μm) and Gd3+(IC50 = 10 μm), whereas verapamil showed no blocking effect. LCC1 may play an important role in the regulation of the cytoplasmic free Ca2+ concentration in root-tip and/or root-cap cells. The question of whether this ion channel is part of the gravitropic signal transduction pathway deserves further investigation.
Gibberellin Dose-Response Curves and the Characterization of Dwarf Mutants of Barley
Authors: Chandler Peter M. , Robertson Masumi
Published: July 2002

Dose-response curves relating gibberellin (GA) concentration to the maximal leaf-elongation rate (LERmax) defined three classes of recessive dwarf mutants in the barley (Hordeum vulgare L.) ‘Himalaya.’ The first class responded to low (10−8–10−6m) [GA3] (as did the wild type). These grd(GA-responsive dwarf) mutants are likely to be GA-biosynthesis mutants. The second class of mutant,gse (GA sensitivity), differed principally in GA sensitivity, requiring approximately 100-fold higher [GA3] for both leaf elongation and α-amylase production by aleurone. This novel class may have impaired recognition between the components that are involved in GA signaling. The third class of mutant showed no effect of GA3 on the LERmax. When further dwarfed by treatment with a GA-biosynthesis inhibitor, mutants in this class did respond to GA3, although the LERmax never exceeded that of the untreated dwarf. These mutants, called elo (elongation), appeared to be defective in the specific processes that are required for elongation rather than in GA signaling. When sln1(slender1) was introduced into these different genetic backgrounds, sln was epistatic to grd and gse but hypostatic toelo. Because the rapid leaf elongation typical ofsln was observed in the grd andgse backgrounds, we inferred that rapid leaf elongation is the default state and suggest that GA action is mediated through the activity of the product of the Sln gene.
Genes Expressed inPinus radiataMale Cones Include Homologs to Anther-Specific and Pathogenesis Response Genes
Authors: Walden Adrian R. , Walter Christian , Gardner Richard C.
Published: July 2002

We describe the isolation and characterization of 13 cDNA clones that are differentially expressed in male cones of Pinus radiata (D. Don). The transcripts of the 13 genes are expressed at different times between meiosis and microspore mitosis, timing that corresponds to a burst in tapetal activity in the developing anthers. In situ hybridization showed that four of the genes are expressed in the tapetum, while a fifth is expressed in tetrads during a brief developmental window. Six of the seven cDNAs identified in database searches have striking similarity to genes expressed in angiosperm anthers. Seven cDNAs are homologs of defense and pathogen response genes. The cDNAs identified are predicted to encode a chalcone-synthase-like protein, a thaumatin-like protein, a serine hydrolase thought to be a putative regulator of programmed cell death, two lipid-transfer proteins, and two homologs of the anther-specific A9 genes from Brassica napus and Arabidopsis. Overall, our results support the hypothesis that many of the reproductive processes in the angiosperms and gymnosperms were inherited from a common ancestor.
Radiotracer and Computer Modeling Evidence that Phospho-Base Methylation Is the Main Route of Choline Synthesis in Tobacco
Authors: McNeil Scott D. , Nuccio Michael L. , Rhodes David , Shachar-Hill Yair , Hanson Andrew D.
Published: July 2002

Among flowering plants, the synthesis of choline (Cho) from ethanolamine (EA) can potentially occur via three parallel, interconnected pathways involving methylation of free bases, phospho-bases, or phosphatidyl-bases. We investigated which pathways operate in tobacco (Nicotiana tabacum L.) because previous work has shown that the endogenous Cho supply limits accumulation of glycine betaine in transgenic tobacco plants engineered to convert Cho to glycine betaine. The kinetics of metabolite labeling were monitored in leaf discs supplied with [33P]phospho-EA, [33P]phospho-monomethylethanolamine, or [14C]formate, and the data were subjected to computer modeling. Because partial hydrolysis of phospho-bases occurred in the apoplast, modeling of phospho-base metabolism required consideration of the re-entry of [33P]phosphate into the network. Modeling of [14C]formate metabolism required consideration of the labeling of the EA and methyl moieties of Cho. Results supported the following conclusions: (a) The first methylation step occurs solely at the phospho-base level; (b) the second and third methylations occur mainly (83%–92% and 65%–85%, respectively) at the phospho-base level, with the remainder occurring at the phosphatidyl-base level; and (c) free Cho originates predominantly from phosphatidylcholine rather than from phospho-Cho. This study illustrates how computer modeling of radiotracer data, in conjunction with information on chemical pool sizes, can provide a coherent, quantitative picture of fluxes within a complex metabolic network.
Bridging the academic‐practitioner divide ‐ a problem of perception?
Authors: Sargeant A. , Sadler‐Smith E. , Dawson A.
Published: July 2002

In 1995 the Universities of Plymouth and Exeter (with backing from the local Training Enterprise Council) took the decision to collaborate on an extensive piece of market research, designed to bring them closer to their local business community. Reviews the findings of that study which relate to businesses’ perceptions of the two institutions. Concludes that university services are perceived as being of the highest quality, but there is little awareness of the full range of services currently on offer. There is also evidence that both institutions need to improve their marketing activities, both in terms of providing an appropriate range of services and by ensuring that these are adequately promoted to the target market.
A Dose of Mentoring
Authors: Garvey Bob
Published: July 2002

This is the second piece in a series of three. Analyses two specific
mentoring partnerships. The mentor relationships are part of an MBA
linked mentor scheme that is running within the Northern Region of the
NHS. Explores the dimensions of the mentoring relationship and attempts
to suggest a “best fit” set of dimensions for mentoring to be effective.
Touches on the gender issue and Learning Style match. Goes on to debate
the effectiveness of mentor development within the scheme and suggests
ways in which this might be improved.
Business mentoring in schools: does it raise attainment?
Authors: Miller Andrew
Published: July 2002

The article describes research into the impact of business and community mentoring in schools on students’ attainment. The research, which was conducted in seven schools during the 1996/97 academic year, was funded by the Department for Education and Employment and three Training and Enterprise Councils. An overview of mentoring schemes and models is followed by analysis of objectives for mentoring from various perspectives. Value‐added analysis was used to measure the impact of mentoring on a sample of mentored students, compared with a similar group of non‐mentored students acting as a control group. The research found a mixed picture in the seven schools involved with girls out‐performing boys across all schools and a small, but positive, impact on the attainment of mentored students. Finally, the researchers offer some recommendations to schools and scheme organisers on how to increase the impact of mentoring upon GCSE attainment.
Three contemporary challenges for OD practitioners
Authors: Neumann Jean E. , Miller Eric J. , Holti Richard
Published: July 2002

Contemporary organisational realities challenge consultants to develop: more up‐to‐date motivational knowledge; the ability and willingness to work with change agents unsympathetic to applied social science; and, facility with methodologies for both cultural and structural change. Changes over the last two decades have resulted in a more diverse motivational picture than the 1950s to 1970s humanistic motivational theories that underlie most organisational development theory and practice. In response, consultants need to develop a portfolio of consultancy methods that enable them to address not only cultural changes (e.g. attitudinal and change) but also structural changes (e.g. organisational design). Today, most clients who hire organisational consultants do so to complement technological and strategic changes anticipated or already undertaken. OD practitioners need to increase their ability to understand and work with change managers, and their consultants, who see the world predominantly through technological and economic eyes.
Manufacturing strategies in the hand tool industry
Authors: Leseure Michel J.
Published: July 2002

The lack of contextual sensitivity of best practices thinking can be a deterrent to innovation in small and medium‐size enterprises if owners and managers feel that the specificity of their companies are not taken into account. Presents cladistics, an evolutionary classification technique, as a tool to be used to craft and validate manufacturing strategies. Cladistics provides a compromise between over‐prescriptive generic business solutions and cost inefficient, high‐risk idiosyncratic solutions. The contribution of cladistics as a qualitative methodology in operations strategy research is illustrated by an evolutionary classification of the hand tool industry and recommendations for innovation in this industry.
The art of cross‐cultural management: “an alternative approach to training and development”
Authors: Estienne Marion
Published: July 2002

Cross‐cultural training and development has often been regarded as principally skills‐based and a “quick fix” for those organizations whose aim is to compete in the global marketplace. It is questionable whether this approach has been successful in helping companies use cultural diversity for competitive advantage. Proposes an alternative approach which takes into account the need to develop a “global mindset” along with new strategies, structures and processes as well as the lifecycle stage of the organization. These conditions can be satisfied by including three elements in any training and development intervention: developing a global mindset; working through a model of cross‐cultural reconciliation; and emphasizing the development of “relational” skills among all members of the organization.
Introduction: discontinuity – a weakness of calculus and beginning of a new era
Authors: Lin Yi
Published: July 2002

In this article, the historical victories and shortfalls of calculus and calculus‐based methods are briefly described so that a need of developing the theory of blown‐ups is given. Listed are several challenges of the theory of blown‐ups to the traditional thinking logic of continuity and characteristics of the theory of blown‐ups.
Using DEA to evaluate the efficiency of secondary schools: the case of Cyprus
Authors: Soteriou Andreas C. , Karahanna Elena , Papanastasiou Constantinos , Diakourakis Manolis S.
Published: July 2002

This study utilizes the methodology of data envelopment analysis (DEA) to assess the efficiency of secondary schools in Cyprus. Apart from evaluating the relative efficiency of schools, the study provides recommendations for improvement to inefficient schools and discusses managerial implications. Furthermore, empirical findings based on an approach to estimate efficiency environmental effects suggest that no efficiency differences exist between schools operating in rural areas compared to those operating in urban areas.
Finite element analysis of a bubble absorber
Authors: Sujatha K.S. , Mani A. , Srinivasa Murthy S.
Published: July 2002

Develops a fine element method employing Galerkin’s approach for the analysis of a vertical tubular bubble absorber working with R22‐DMF as working fluid. Aims to provide an understanding of the absorption process which helps in the design of bubble absorbers. Numerical experiments have also been carried out with ammonia‐water combination for the sake of comparison with the results in the literature and the agreement is found to be good. Suggests a correlation for mass transfer coefficient for vertical tubular bubble absorbers working with R22‐DMF. The use of the correlation can either be in estimating the mass transfer rates, or in fixing up the major design parameters such as diameter and length required for complete absorption.
Numerical study of three‐dimensional non‐Darcy forced convection in a square porous duct
Authors: Chen G. , Hadim H.A.
Published: July 2002

The objective of the present work was to perform a detailed numerical study of laminar forced convection in a three‐dimensional square duct packed with an isotropic granular material and saturated with a Newtonian fluid. Hydrodynamic and heat transfer results are reported for three different thermal boundary conditions. The flow in the porous medium was modeled using the semi‐empirical Brinkman‐Forchheimer‐extended Darcy model which also included the effects of variable porosity and thermal dispersion. Empirical models for variable porosity and thermal dispersion were determined based on existing three‐dimensional experimental measurements. Parametric studies were then conducted to investigate the effects of particle diameter, Reynolds number, Prandtl number and thermal conductivity ratio. The results showed that channeling phenomena and thermal dispersion effects are reduced considerably in a three‐dimensional duct compared with previously reported results for a two‐dimensional channel. It was found that the Reynolds number affects mainly the velocity gradient in the flow channeling region, while the particle diameter affects the width of the flow channeling region. As the Reynolds number increases or as the particle diameter decreases (i.e., when the inertia and thermal dispersion effects are enhanced), the Nusselt number increases. The effects of varing the Prandtl number on the magnitude of the Nusselt number were found to be more significant than those of the thermal conductivity ratio. Finally, the effects of varing the duct aspect ratio on the friction factor can be neglected for small particle diameter (Dp ≤ 0.01) or for high particle Reynolds number (Red ≥ 1000) due to the dominant bulk damping resistance from the porous matrix (Darcy term) or strong inertia effects (Forchheimer term), respectively.
Organisational self‐assessment: measuring educational quality in two paradigms
Authors: Gore Chris , Bond Chris , Steven Valerie
Published: July 2002

Draws on contrasting epistemological stances with regard to quality enhancement in the context of higher education and develops the work of Schon (1987), Fish (1992) and Bond (1996, 1998) concerning the technical‐rational view of professionalism and the more generous notion of professional‐artistry. Identifies how these ideas can be useful in the analysis and design of processes for organisational self‐assessment and is based on participatory action research being conducted in a UK university preparing for a major Government quality review in the year 2000. Two cases are presented, each based on the key assumptions and foundations which underpin one of the two contrasting paradigms. Concludes by exploring the key issues of conjunction and disjunction between the two paradigms of organisational self‐assessment, and proposes a framework within which the two approaches can co‐exist.
Salt‐induced stabilization of apoflavodoxin at neutral pH is mediated through cation‐specific effects
Authors: Maldonado Susana , Irún María Pilar , Campos Luis Alberto , Rubio José Antonio , Luquita Alejandra , Lostao Anabel , Wang Renjie , García‐Moreno E. Bertrand , Sancho Javier
Published: July 2002

Electrostatic contributions to the conformational stability of apoflavodoxin were studied by measurement of the proton and salt‐linked stability of this highly acidic protein with urea and temperature denaturation. Structure‐based calculations of electrostatic Gibbs free energy were performed in parallel over a range of pH values and salt concentrations with an empirical continuum method. The stability of apoflavodoxin was higher near the isoelectric point (pH 4) than at neutral pH. This behavior was captured quantitatively by the structure‐based calculations. In addition, the calculations showed that increasing salt concentration in the range of 0 to 500 mM stabilized the protein, which was confirmed experimentally. The effects of salts on stability were strongly dependent on cationic species: K+, Na+, Ca2+, and Mg2+ exerted similar effects, much different from the effect measured in the presence of the bulky choline cation. Thus cations bind weakly to the negatively charged surface of apoflavodoxin. The similar magnitude of the effects exerted by different cations indicates that their hydration shells are not disrupted significantly by interactions with the protein. Site‐directed mutagenesis of selected residues and the analysis of truncation variants indicate that cation binding is not site‐specific and that the cation‐binding regions are located in the central region of the protein sequence. Three‐state analysis of the thermal denaturation indicates that the equilibrium intermediate populated during thermal unfolding is competent to bind cations. The unusual increase in the stability of apoflavodoxin at neutral pH affected by salts is likely to be a common property among highly acidic proteins.
Heat Transfer From a Finned Surface in Ducted Air Jet Suction and Impingement
Authors: Brignoni Luis A. , Garimella Suresh V.
Published: July 2002

Experimental measurements were obtained to characterize the thermal performance of ducted air suction in conjunction with a pin-fin heat sink. Four single nozzles of different diameters and two multiple-nozzle arrays were studied at a fixed nozzle-to-target distance, for different turbulent Reynolds numbers 5000⩽Re⩽20,000. Variations of nozzle-to-target distance, i.e., open area, in ducted suction were found to have a strong effect on heat transfer especially with the larger diameter single nozzle and both multiple-nozzle arrays. Enhancement factors were computed with the heat sink in suction flow, relative to a bare surface, and were in the range of 8.3 to 17.7, with the largest value being obtained for the nine-nozzle array. Results from the present study on air jet suction are compared with previous experiments with air jet impingement on the pin-fin heat sink. Average heat transfer coefficients and thermal resistance values are reported for the heat sink as a function of Reynolds number, air flow rate, and pumping power. [S1043-7398(00)00903-8]
Ingredient-Wise Study of Flux Characteristics in the Ceramic Membrane Filtration of Uncontaminated Synthetic Metalworking Fluids, Part 2: Analysis of Underlying Mechanisms
Authors: Skerlos Steven J. , Rajagopalan N. , DeVor Richard E. , Kapoor Shiv G. , Angspatt V. Don
Published: July 2002

Part 2 of this paper reveals the predominant mechanism of flux decline during microfiltration of the synthetic MWF described in Part 1 of this paper. An analysis of flux data obtained during the experimental investigation suggests that adsorptive interactions occur at the membrane surface. Field Emission Environmental Scanning Electron Microscopy (FE-ESEM) images of aluminum oxide membranes after MWF microfiltration illustrate that adsorption leads to a reduction in pore diameter that serves to reduce flux. The majority of the adsorption is accounted for by a single lubricant additive in the MWF formulation. FE-ESEM images also reveal that the mechanism of flux decline for the defoamer varies depending on the presence of lubricant additive in solution. In the absence of lubricant additive, the defoamer forms a cake layer at the membrane surface. In the presence of the lubricant additive, the defoamer adsorbs to the surface of the membrane with the lubricant additive to constrict pores. In contrast to the lubricant additive and defoamer, base fluid flux decline observed after specialty additive exposure cannot be accounted for by adsorption leading to pore constriction. [S1087-1357(00)01203-X]
Surface Integrity of Die Material in High Speed Hard Machining, Part 2: Microhardness Variations and Residual Stresses
Authors: El-Wardany T. I. , Kishawy H. A. , Elbestawi M. A.
Published: July 2002

The main objective of this paper is to investigate the quality and integrity of the surface produced during high speed hard machining (HSHM) of D2 tool steel in its hardened state (60–62 HRc). Polycrystalline Cubic Boron Nitride (PCBN) tools are used in this study. The results obtained from the micro-graphical analysis of the surface produced are presented in Part 1 of this paper. In Part 2 micro-hardness and residual stress analyses are presented. Microhardness measurements are conducted beneath the machined surface. X-ray diffraction analysis is performed to obtain the residual stress distribution beneath the surface. Analytically, a 3-D thermo-elasto-plastic finite element model is developed to predict the residual stresses induced in the workpiece surface. In the model the cutting zone is specified based on the tool condition (i.e., sharp or worn). The finite element analysis demonstrates the significant effect of the heat generated during cutting on the residual stress distribution. The results illustrate the possibility of minimizing the high tensile residual stresses produced in the workpiece surface, by selecting the appropriate depth of cut. A good correlation between the analytical and predicted residual stress is obtained. [S1087-1357(00)00804-2]
Parametric Study of Heat Transfer in Injection Molding—Effect of Thermal Contact Resistance
Authors: Sridhar L. , Sedlak B. M. , Narh K. A.
Published: July 2002

Thermal contact resistance (TCR) plays an important role in the heat transfer during injection molding. However, there is no consensus on the magnitude of TCR to be used in simulation as most of the reported results are based on steady state experiments. A numerical simulation of the heat transfer in injection molding is used in studying its effect and significance. The TCR is shown to attain its maximum magnitude in the postfilling period, and more accurate values than those available in literature are required for a better simulation of the postfilling stage. The effect of interface gap formation between the plastic and the mold on the contact resistance is also studied. This shows that the gap may have contributed to the high magnitude of TCR reported from the one experimental study of TCR in injection molding. However, the gap formation is shown to be dependent on the part geometry as well as processing conditions—in terms of shrinkage and warpage effects. The gap is both a function of time and space (location on the part surface) and this makes any experimental determination of the gap and TCR difficult. [S1087-1357(00)01404-0]
Creep-Damage Analysis: Comparison Between Coupled and Uncoupled Models
Authors: Bhandari S. , Feral X. , Bergheau J.-M. , Mottet G. , Dupas P. , Nicolas L.
Published: July 2002

Numerical simulation of creep rupture of a reactor pressure vessel in a severe hypothetical accident needs to perfectly take account of interactions between creep phenomena and damage. The continuous damage theory enables to formulate models strongly coupling elasto-visco-plasticity and damage. Such models have been implemented in various computer codes and, in particular, in ASTER at Electricite´ de France, CASTEM 2000 at Commissariat a` l’Energie Atomique and SYSTUS+® at SYSTUS International. The objective of this paper is to present briefly a validation study of the three different numerical implementations and to compare the coupled approach to an uncoupled one on an example of a cylinder of the program “RUPTHER,” under internal pressure and heated to a temperature of 700°C. [S0094-9930(00)01004-0]
Sliding Mode Control of Nonlinear Mechanical Vibrations1
Authors: Sira-Ramı´rez Hebertt , Llanes-Santiago Orestes
Published: July 2002

In this article we illustrate how the property of differential flatness can be advantageously joined to the sliding mode controller design methodology for the active stabilization of nonlinear mechanical vibration systems. The proposed scheme suitably combines off-line trajectory planning and an on-line “smoothed” sliding mode feedback trajectory tracking scheme for regulating the evolution of the flat output variables toward the desired equilibria. [S0022-0434(00)00404-4]
Stress Analysis and Design for Cyclic Loading
Authors: Carter P.
Published: July 2002

A finite element implementation of rapid cycle analysis is described and demonstrated. It forms part of a comprehensive framework for static structural analysis which consists of: linear elastic analysis, limit load or nonlinear elastic analysis, and rapid cycle analysis. This approach allows for complex material and loading behavior, but is computationally more efficient and easier to perform than full inelastic analysis. It indicates more complex behavior than can be inferred from linear elastic analysis. The objective of this paper is to calculate shakedown, reverse plasticity, ratcheting, and the increase in strain rate as a result of cyclic mechanical and thermal loading. Results are presented in the form of interaction diagrams, similar to the O’Donnell-Porowski plot in the ASME BPV Code, which are effective design tools. [S0094-9930(00)01604-8]
Two-Dimensional Measurements of Lubricant Spreading on Diamond-Like-Carbon Surface Using Image Processing on Fringe Patterns Formed by Michelson Interferometry
Authors: Mitsuya Yasunaga , Zhang Hedong , Ishida Sakiko
Published: July 2002

A Michelson interferometer based on the Linnik microscope configuration has been constituted and applied to the measurement of lubricant spreading on diamond-like-carbon (DLC) surface. Performing image processing on the fringe patterns formed by the interferometer, the lubricant thickness, as well as the spreading behavior can be investigated. This method provides complete line profiles in two dimensions and permits direct observation of the spreading phenomena, in contrast to the conventional point-by-point scanning method. To improve the measurement accuracy, a fringe following technique and a noise suppression technique were introduced. The fringe following technique successfully prevented a fringe shift over the visual field and thus suppressed the pseudo phase shift caused by a fringe shift. The spatially fixed noise due to non-uniform laser beams and flaws in optical components was also efficiently suppressed by the noise compensation method. From the calculation of multiple beam interference in a stratified medium, it is found that reduction in sensitivity due to additional reflections from underlayers is effectively prevented if the lubricant is observed through a glass disk using reflections on the back surfaces of the glass and lubricant, instead of being observed on a disk using the front surface reflections. Utilizing this advantage, a novel scheme was employed to give maximum sensitivity in which lubricant was coated on the back side of a glass disk whose front surface was coated with non-reflecting film and whose back surface was sputtered with the proper thickness of DLC. The enhanced resolution attained by the new scheme was experimentally confirmed by observing lubricant on the back surface of the glass disk and the front surface of a magnetic disk.
Directional Spectral Emittance of a Packed Bed: Correlation Between Theoretical Prediction and Experimental Data
Authors: Lopes Roge´rio , Moura Luı´s M. , Baillis Dominique , Sacadura Jean-Franc¸ois
Published: July 2002

Directional spectral emittance of an absorbing and scattering isothermal system of packed spheres is predicted by a radiative model based on the discrete ordinates method. Radiative properties for the bed of packed opaque spheres are obtained using geometric optics laws corrected with a scaling factor to take into account the dependent scattering. This model requires the knowledge of several parameters. Particle diameter and porosity can be easily obtained, but particle hemispherical spectral reflectivity is very difficult to obtain a priori. This particle reflectivity is determined by an identification method (Gauss method of linearization) applied to bidirectional spectral reflectance data obtained from an experimental device using a Fourier transform infrared spectrometer. Directional spectral emittance is measured using a direct radiometric technique that has been recently proposed. For a system of packed opaque spheres at high temperature, good agreement is observed between experimental results of directional spectral and computed theoretical data.
Exact Solutions for Out-of-Plane Vibration of Curved Nonuniform Beams
Authors: Lee S. Y. , Chao J. C.
Published: July 2002

The governing differential equations for the out-of-plane vibrations of curved nonuniform beams of constant radius are derived. Two physical parameters are introduced to simplify the analysis, and the explicit relations between the torsional displacement, its derivative and the flexural displacement are derived. With these explicit relations, the two coupled governing characteristic differential equations can be decoupled and reduced to one sixth-order ordinary differential equation with variable coefficients in the out-of-plane flexural displacement. It is shown that if the material and geometric properties of the beam are in arbitrary polynomial forms, then the exact solutions for the out-of-plane vibrations of the beam can be obtained. The derived explicit relations can also be used to reduce the difficulty in experimental measurement. Finally, two limiting cases are considered and the influence of taper ratio, center angle, and arc length on the first two natural frequencies of the beams are illustrated.
Unsteady Flow/Quasi-Steady Heat Transfer Computations on a Turbine Rotor and Comparison With Experiments
Authors: Korakianitis T. , Papagiannidis P. , Vlachopoulos N. E.
Published: July 2002

The unsteady flow in stator–rotor interactions affects the structural integrity, aerodynamic performance of the stages, and blade-surface heat transfer. Numerous viscous and inviscid computer programs are used for the prediction of unsteady flows in two-dimensional and three-dimensional stator–rotor interactions. The relative effects of the various components of flow unsteadiness on heat transfer are under investigation. In this paper it is shown that for subsonic cases, the reduced frequency parameter for boundary-layer calculations is about two orders of magnitude smaller than the reduced frequency parameter for the core flow. This means that for typical stator–rotor interactions, the unsteady flow terms are needed to resolve the location of disturbances in the core flow, but in many cases the instantaneous disturbances can be input in steady-flow boundary-layer computations to evaluate boundary-layer effects in a quasi-steady approximation. This hypothesis is tested by comparing computations with experimental data on a turbine rotor for which there are extensive experimental heat transfer data available in the open literature. An unsteady compressible inviscid two-dimensional computer program is used to predict the propagation of the upstream stator disturbances into the downstream rotor passages. The viscous wake (velocity defect) and potential flow (pressure fluctuation) perturbations from the upstream stator are modeled at the computational rotor–inlet boundary. The effects of these interactions on the unsteady rotor flow result in computed instantaneous velocity and pressure fields. The period of the rotor unsteadiness is one stator pitch. The instantaneous velocity fields on the rotor surfaces are input in a steady-flow differential boundary-layer program, which is used to compute the instantaneous heat transfer rate on the rotor blades. The results of these quasi-steady heat-transfer computations are compared with the results of unsteady heat transfer experiments and with the results of previous unsteady heat transfer computations. The unsteady flow fields explain the unsteady amplitudes and phases of the increases and decreases in instantaneous heat transfer rate. It is concluded that the present method is accurate for quantitative predictions of unsteady heat transfer in subsonic turbine flows.
Transformation Induced Plasticity: Mechanisms and Modeling
Authors: Cherkaoui M.
Published: July 2002

TRansformation Induced Plasticity (TRIP) phenomenon results from the competition between two basic mechanisms, namely the orientation and accommodation. An accurate description of such a behavior is closely related to a good evaluation of the contribution of each mechanism in the overall response of the material. The main objective of this work is to provide an analysis of the different mechanisms at the microscale governing the TRIP phenomenon. The interaction between these mechanisms is experimentally displayed through nonproportional loading paths corresponding to the “creep” test. A micromechanical model is presented and tested under such conditions.
Orthotropic Hyperelasticity in Terms of an Arbitrary Molecular Chain Model
Authors: Bischoff J. E. , Arruda E. M. , Grosh K.
Published: July 2002

There are many statistical mechanical models of long-chain models, two of which are the freely jointed chain model and the wormlike chain model. A continuum constitutive law for hyperelastic orthotropic materials has recently been developed using the freely jointed chain model as its basis. In this note, the continuum strain energy function is recast in general terms allowing for the incorporation of an arbitrary macromolecular constitutive model. In particular, the orthotropic constitutive model is recast using the wormlike chain model in place of the freely jointed chain model and the effects of this alternation are examined.
Ground-Coupled Heat and Moisture Transfer from Buildings Part 2–Application
Authors: Deru Michael P. , Kirkpatrick Allan T.
Published: July 2002

In this paper, the effects of moisture on the heat transfer from two basic types of building foundations, a slab-on-grade and a basement, are examined. A two-dimensional finite element heat and moisture transfer program is used to show the effects of precipitation, soil type, foundation insulation, water table depth, and freezing on the heat transfer from the building foundation. Comparisons are made with a simple heat conduction model to illustrate the dependency of the soil thermal conductivity on moisture content.
Contact Fatigue Failure of Ultra-High Molecular Weight Polyethylene Bearing Components of Knee Prostheses
Authors: Kennedy F. E. , Currier J. H. , Plumet S. , Duda J. L. , Gestwick D. P. , Collier J. P. , Currier B. H. , Dubourg M-C.
Published: July 2002

The objective of this work has been to study the origin of surface failures in UHMWPE tibial bearings of total knee replacements. Earlier examination of hundreds of retrieved prostheses, along with analysis of the properties of UHMWPE material from retrieved bearings, had shown that a large number of the bearings suffered from subsurface oxidation. This oxidation was related to the gamma irradiation used to sterilize the tibial bearings. Mechanical properties of the polymer were significantly deteriorated in the oxidized region, with the most severe reduction of strength and ductility occurring about 1 mm beneath the contact surface. In this work the contact stress distribution in the bearings was analyzed, and tribotesting of the bearing materials was carried out under simulated service conditions. Fatigue cracks and delamination developed in bearings tested in a knee simulator and in rolling/sliding test specimens, and the damage was similar to that found in retrieved tibial bearings. The fatigue cracks invariably initiated in the embrittled oxidized layer, and the depth of that layer determined the depth at which the cracks began. The stress analysis showed that the maximum shear stress and von Mises equivalent stress reached high levels in the subsurface oxidized zone where the delamination and contact fatigue failures initiated. [S0742-4787(00)04401-5]
The Measurement of Local Wall Heat Transfer in Stationary U-Ducts of Strong Curvature, With Smooth and Rib-Roughened Walls
Authors: Iacovides Hector , Jackson David C. , Kelemenis George , Launder Brian E.
Published: July 2002

The paper presents some of our recent experimental investigations of convective heat transfer in flow through stationary passages relevant to gas turbine blade-cooling applications. The main objective of this effort is to produce local heat transfer data for CFD validation. Local Nusselt number measurements in flows through round-ended U-bends of square cross section, with and without artificial wall roughness, are presented. Our earlier LDA measurements of flows through these passages are first briefly reviewed and then the liquid-crystal technique for the measurement of local wall heat transfer inside passages of complex geometries is presented. Tightly curved U-bends generate strong secondary motion and cause flow separation at the bend exit, which substantially raise turbulence levels. Wall heat transfer is significantly increased, especially immediately downstream of the U-bend, where it is over two times higher than in a straight duct. The local heat transfer coefficient around the perimeter of the passage is also found to vary considerably because of the curvature-induced secondary motion. The introduction of surface ribs results in a further increase in turbulence levels, a reduction in the size of the curvature-induced separation bubble, and a complex flow development after the bend exit with additional separation regions along the outer wall. Heat transfer levels in the straight sections are more than doubled by the introduction of ribs. The effects of the bend on the overall levels of Nusselt number are not as strong as in the smooth U-bend, but are still significant. The effects of the bend on the perimetral variation of local heat transfer coefficients within the ribbed downstream section are also substantial. [S0889-504X(00)00802-3]
Zirconium Nitride by XPS
Authors: Milošev Ingrid , Strehblow Hans-Henning , Navinšek Boris , Panjan Peter
Published: July 2002

Zirconium nitride (ZrN) coatings have been deposited on polished steel substrates by a plasma-beam sputtering technique in a Sputron apparatus (Balzers A. G.) at 200 °C. A thin intermediate layer of Zr (0.08 μm) was deposited between the substrate and the 2.8 μm thick ZrN coating. The average roughness, Ra, of the substrate was <0.04 μm, whereas after the deposition Ra values between 0.06 and 0.08 μm were measured for ZrN coatings. Coatings exhibit a fine grain structure of the grain size <100 nm. The XPS measurements were performed in an Escalab 200-X spectrometer (VG Instruments) using non-monochromatized Al Kα radiation from a twin Mg/Al anode operating at 300 W. The hemispherical energy analyzer was operated in the CAE mode with a constant pass energy of 20 eV. In the present paper the following spectra are presented: survey spectrum, spectra of major elements zirconium and nitrogen (Zr 3d and N 1s), spectra of minor elements oxygen and carbon (O 1s and C 1s), and valence band spectrum. Spectra were background subtracted using a Shirley method. Peak positions and widths were determined from a least squares fitting procedure.
Plasma injection with helicon sources
Authors: Chen Francis F. , Jiang Xicheng , Evans John D.
Published: July 2002

An exhaustive set of measurements has been made to find the optimum conditions for plasma injection into a processing chamber using small helicon sources with low magnetic fields B. It is found that the plasma density decreases, rather than increases, with B, as in normal helicon discharges. The design of the field coil and flange caused this effect; with a different design, normal operation was obtained. This experiment provides data on the area coverage of individual helicon discharges for the design of large-area, distributed plasma sources.
Mechanism of laser-induced nanomodification on hydrogen-passivated Si(100) surfaces underneath the tip of a scanning tunneling microscope
Authors: Mai Z. H. , Lu Y. F. , Huang S. M. , Chim W. K. , Pan J. S.
Published: July 2002

Laser-induced nanomodification on hydrogen (H)-passivated Si(100) surfaces has been carried out underneath the tip of a scanning tunneling microscope (STM) in ambient air. The created features were characterized using STM, atomic-force microscopy (AFM), and Auger electron spectroscopy (AES). The features appeared as depressed regions in STM images, while they appeared as protruded regions in AFM images. Oxygen was detected in a modified 2×2 μm2 square region by AES, while no oxygen was detected elsewhere on the same sample surface. The experiment results and mechanism are discussed. Nano-oxide patterns, such as lines and dots, have been created. Dependence of oxide apparent depth on laser intensity, laser pulse numbers, tunneling current during modification, and laser incidence angle has been investigated.
Surface-induced optical anisotropy of Si and Ge
Authors: Rossow U. , Mantese L. , Aspnes D. E.
Published: July 2002

We compare surface-induced optical anisotropy spectra measured by reflectance difference/anisotropy spectroscopy of Si and Ge. Our previous work on Si has shown that we can roughly distinguish two types of contributions to the optical response of surfaces: direct contributions involving surface state transitions and indirect contributions in which the surface modifies the bulk response. We demonstrate here that this view is valid for Ge as well. For Si the indirect surface contributions exhibit three extreme, basic line shapes, which are all related to the bulk dielectric function εb or nanostructured material. We demonstrate that this line shape analysis can also be applied to Ge.