bluuebunny/crossref_metadata_2025 huggingface dataset:
Data‐driven variation source identification for manufacturing process using the eigenspace comparison method
Authors: Jin Nong , Zhou Shiyu
Published: March 2006

Variation reduction of manufacturing processes is an essential objective of process quality improvement. It is highly desirable to develop a methodology of variation source identification that helps quickly identify the variation sources, hence leading to quality improvement and cost reduction in manufacturing systems. This paper presents a variation source identification method based on the analysis of the covariance matrix of process quality measurements. The identification procedure utilizes the fact that the eigenspace of the quality measurement covariance matrix can be decomposed into a subspace due to variation sources and a subspace purely due to system noise. The former subspaces for different samples will be the same if the same variation sources dominate. A testing procedure is presented, which can determine the closeness of the subspaces under sampling uncertainty. A case study is conducted to illustrate the effectiveness of this methodology. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006.
Age‐dependent and task‐related volume changes in the mushroom bodies of visually guided desert ants, Cataglyphis bicolor
Authors: Kühn‐Bühlmann Simone , Wehner Rüdiger
Published: March 2006

Desert ants of the genus Cataglyphis are skillful long‐distance navigators employing a variety of visual navigational tools such as skylight compasses and landmark guidance mechanisms. However, the time during which this navigational toolkit comes into play is extremely short, as the average lifetime of a Cataglyphis forager lasts for only about 6 days. Here we show, by using immunohistochemistry, confocal microscopy, and three‐dimensional reconstruction software, that even during this short period of adult life, Cataglyphis exhibits a remarkable increase in the size of its mushroom bodies, especially of the visual input region, the collar, if compared to age‐matched dark‐reared animals. This task‐related increase rides on a much smaller age‐dependent increase of the size of the mushroom bodies. Due to the variation in body size exhibited by Cataglyphis workers we use allometric analyses throughout and show that small animals exhibit considerably larger task‐related increases in the sizes of their mushroom bodies than larger animals do. It is as if there were an upper limit of mushroom body size required for accomplishing the ant's navigational tasks. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006
Lesion‐induced neurogenesis in the hypothalamus is involved in behavioral recovery in adult ring doves
Authors: Chen Gang , Bonder Edward M. , Cheng Mei‐Fang
Published: March 2006

Although neurogenesis in the brain of adult vertebrates is region dependent, lesion induces generation of new neurons in non‐neurogenic brain regions. These findings raise the question of the role of new neurons in brain repair and functional recovery. We addressed this question by applying previous observations that electrolytic lesion induced neurogenesis in the ventromedial nucleus (VMN) of the hypothalamus in adult ring doves. Such lesions disrupted the male's courtship behavior, which could be reinstated after rehabilitation with a female. We investigated whether lesion‐induced newborn neurons in the VMN facilitate the recovery of courtship behavior in the lesioned birds. We conducted systematic observations of cytological, morphological, and neuroanatomical changes in the lesioned VMN, and concurrently we monitored behavioral changes. Using a multitude of specific cell markers, we found a well‐circumscribed cellular zone that proliferated actively. This highly proliferative zone initially appeared along the periphery of the lesion site, where cells had high levels of expression of neuronal, glial, and neurovascular markers. As newborn neurons matured at the lesion site, the necrosis gradually decreased, whereas a downsized proliferative zone relocated to a region ventral to the VMN. Some of the mature neurons were found to project to the midbrain vocal nuclei. Restoration of these projection neurons coincided with the recovery of courtship vocalization. Finally, we found that a social factor, that is, when the male doves were cohoused with a mate, facilitated neurogenesis and behavioral recovery. These results suggest that lesion‐induced neurogenesis contributes to behavioral recovery in adult animals. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006
Activity‐dependent release of tissue plasminogen activator from the dendritic spines of hippocampal neurons revealed by live‐cell imaging
Authors: Lochner Janis E. , Honigman Leah S. , Grant Wilmon F. , Gessford Sarah K. , Hansen Alexis B. , Silverman Michael A. , Scalettar Bethe A.
Published: March 2006

Tissue plasminogen activator (tPA) has been implicated in a variety of important cellular functions, including learning‐related synaptic plasticity and potentiating N‐methyl‐D‐aspartate (NMDA) receptor‐dependent signaling. These findings suggest that tPA may localize to, and undergo activity‐dependent secretion from, synapses; however, conclusive data supporting these hypotheses have remained elusive. To elucidate these issues, we studied the distribution, dynamics, and depolarization‐induced secretion of tPA in hippocampal neurons, using fluorescent chimeras of tPA. We found that tPA resides in dense‐core granules (DCGs) that traffic to postsynaptic dendritic spines and that can remain in spines for extended periods. We also found that depolarization induced by high potassium levels elicits a slow, partial exocytotic release of tPA from DCGs in spines that is dependent on extracellular Ca+2 concentrations. This slow, partial release demonstrates that exocytosis occurs via a mechanism, such as fuse‐pinch‐linger, that allows partial release and reuse of DCG cargo and suggests a mechanism that hippocampal neurons may rely upon to avoid depleting tPA at active synapses. Our results also demonstrate release of tPA at a site that facilitates interaction with NMDA‐type glutamate receptors, and they provide direct confirmation of fundamental hypotheses about tPA localization and release that bear on its neuromodulatory functions, for example, in learning and memory. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006
Facing up to the challenges of the practice development unit: a leader's perspective
Authors: Sheehan Nicola , Hayles Jean
Published: March 2006

The Orthopaedic Unit at the Calderdale Royal Hospital began its journey to become a Practice Development Unit (PDU) in October 2003. The Unit has currently achieved Stage 1 accreditation and are presently striving to achieve full accreditation.

One of the important factors required in a successful PDU is having effective leadership that is able to both motivate the team and achieve the desired results.

This article is a reflective piece examining the problems and obstacles that were encountered by the two leaders of the PDU on their journey to be a fully accredited unit. These problems included lack of team ownership, lack of devolved leadership and lack of time. The article also sets out ways in which these problems have been overcome, and gives the reader practical tips on things to take into account before becoming a leader of a PDU. Copyright © 2006 John Wiley & Sons Ltd
Bridging the gap: learning with patient teachers in health professional education
Authors: O'Neill Fiona , Morris Penny , Symons Jools
Published: March 2006

This paper explores the value and contribution of patient voices in health professional education. The important changes in policy and practice that are slowly transforming the way that services are provided and experienced by people who have a long‐term condition challenges traditional approaches to health professional education. The authors describe their philosophy and approach that supports health professionals to learn from patient voices. The value of the approach extends beyond the insights and support for learners but also has an impact on the individuals who contribute their expertise and knowledge as part of the Patients as Teachers team. Valuing and supporting members of the local community to get involved in professional education is one way of opening up the ‘ivory tower’ and challenges assumptions about who are the teachers and who are the learners. Copyright © 2006 John Wiley & Sons, Ltd.
Innovation in Substance Misuse Services: the contribution of the health care assistant
Authors: Ord Stephen , Sims John
Published: March 2006

This article describes the unique developing role of the health care assistant within a statutory substance misuse service in North West Wales. The main focus of the paper is how the evolving role of the health care assistant has contributed to the enhancement of services delivered to intravenous (illicit) drug users. The first author is the only health care assistant employed by the Substance Misuse Service and was a voluntary worker prior to appointment within the trust. A description is given of how the ‘mould’ was broken. An explanation of how this came about reflects the innovative changes that have been facilitated by a management style resulting in a better quality of service provision. The role is still developing within the service but to date has been instrumental in the generation of sustainable innovation within the service. Copyright © 2006 John Wiley & Sons, Ltd.
Differential post‐translational modifications of transthyretin in Alzheimer's disease: A study of the cerebral spinal fluid
Authors: Biroccio Antonino , del Boccio Piero , Panella Marta , Bernardini Sergio , Di Ilio Carmine , Gambi Domenico , Stanzione Paolo , Sacchetta Paolo , Bernardi Giorgio , Martorana Alessandro , Federici Giorgio , Stefani Alessandro , Urbani Andrea
Published: March 2006

Transthyretin (TTR) is a 55 kDa homotetrameric protein. TTR in the cerebral spinal fluid (CSF) is primarily synthesized by the choroid plexus. TTR can bind to the β‐amyloid peptide and a number of familial amyloidosis diseases (familial amyloid polyneuropathy) have been associated with its allele variants. In a transgenic mice model overexpression of TTR was positively correlated with a neuroprotective effect from the pathogenic APPsw mutation. TTR has a free reactive sulphydryl moiety located on the Cys10 residue which has been implicated to undergo a variety of oxidation reactions. To examine the neuroprotective role of TTR, we investigated the conjugated forms of TTR with cysteine (Cys) and cysteinglycine (CsyGly) in the CSF of 39 probable Alzheimer's disease (AD)‐affected subjects and in a cohort of subjects without cognitive impairment (27 subjects). Linear MALDI‐TOF MS experiments were employed to obtain high‐resolution protein profiling of TTR isoforms. Nano‐LC‐TANDEM MS combined with reflectron MALDI‐TOF‐MS was used to unequivocally assign the investigated TTR‐conjugate signals. Our results indicate a differential distribution of TTR‐Cys and TTR‐CsyGly adducts. Both oxidized forms of TTR are significantly less abundant in the AD group (p = 0.0001). The investigated population (66 subjects) was then diagnosed using the ratio of conjugated TTR to free TTR in each subject. A sensitivity >90% and a specificity >70% were derived from a receiver operating characteristic curve when the overall cohort is analysed by the TTR‐Cys signals. This manuscript is the first report describing the presence of differential post‐translational oxidations of TTR in the CSF of AD patients.
Synthesis of poly(glycolic acid) in ionic liquids
Authors: Dali Souad , Lefebvre Hervé , Gharbi Rachid El , Fradet Alain
Published: March 2006

The synthesis of poly(glycolic acid) (PGA) by polyesterification of glycolic acid was studied using ionic liquids, mainly 1,3‐dialkylimidazolium salts, as reaction media. The 1H NMR spectra of PGA oligomers were assigned and end‐group signals were used to follow the reaction. Low PGA yields were obtained by the direct polyesterification of glycolic acid at 200–240 °C, because of monomer evaporation during the reaction. On the other hand, PGAs of DPn up to 45 were obtained by the postpolycondensation of a preformed oligomer in 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)amide (BMIm+Tf2N−). The precipitation of PGA in reaction medium at long reaction times limited the achievable molar mass. Rate constants were determined for catalyzed and noncatalyzed reactions, assuming a second‐order reaction mechanism. The efficiency of esterification catalysts such as Zn(OAc)2 was low in these media, as only about twofold increases in reaction rate were observed. This was assigned to the preferential interaction of Zn2+ with ionic liquid anion instead of the polymer carboxylic acid end‐groups. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3025–3035, 2006
Controlled grafting from poly(vinylidene fluoride) films by surface‐initiated reversible addition–fragmentation chain transfer polymerization
Authors: Chen Yiwang , Sun Wei , Deng Qilan , Chen Lie
Published: March 2006

A reversible addition–fragmentation chain transfer (RAFT) polymerization technique was applied to graft polymerize brushes of poly(methyl methacrylate) (PMMA) and poly(poly(ethylene glycol) monomethacrylate) (PPEGMA) from poly(vinylidene fluoride) (PVDF) surfaces. PVDF surfaces were exposed to aqueous LiOH, followed by successive reductions with NaBH4 and DIBAL‐H to obtain hydroxyl functionality. Azo‐functionalities, as surface initiators for grafting, were immobilized on the PVDF surfaces by esterification of 4,4′‐azobis(4‐cyanopentanoic acid) and the surface hydroxyl groups. The chemical composition and surface topography of the graft‐functionalized PVDF surfaces were characterized by X‐ray photoelectron spectroscopy, attenuated total reflectance‐FTIR spectroscopy, and atomic force microscopy. Kinetics studies revealed a linear increase in the graft concentration of PMMA and PPEGMA with the reaction time, indicating that the chain growth from the surface was consistent with a “controlled” or “living” process. The living chain ends were used as the macroinitiator for the synthesis of diblock copolymer brushes. Water contact angles on PVDF films were reduced by surface grafting of PEGMA and MMA. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3071–3082, 2006
Ultrahigh molecular weight polyethylene produced by a bis(phenoxy‐imine) titanium complex supported on latex particles
Authors: Naundorf C. , Matsui S. , Saito J. , Fujita T. , Klapper M. , Müllen K.
Published: March 2006

The applicability of latex particle supports for non‐Cp type metallocene catalysts for ethylene polymerization is presented. Polystyrene latex particles were prepared by miniemulsion polymerization and functionalized with poly(ethyleneoxide)chains and pyridyl groups on the surface. These latex particles were chosen to demonstrate that a support with nucleophilic substituents on the surface can act as a carrier for a (phenoxy‐imine) titanium complex (titanium FI‐catalyst) to produce ultrahigh molecular weight polyethylene (UHMWPE). The composition of the support, the concentration of pyridyl groups on the surface, and the crosslinking of the support were optimized to provide a system where the FI‐catalyst resulted in the formation of polyethylene with a Mw of more than 6,000,000 and a relatively narrow molecular weight distribution of 3.0 ± 0.5. High activities for long polymerization times greater than 6 h resulted in a catalyst system exhibiting productivities of up to 15,000 g PE/g cat. or 7,000,000 g PE/g Ti. The resulting polymer properties showed that nucleophilic groups on the latex particle support did not negatively impact the catalyst by blocking the active site but instead created a stable environment for the titanium catalyst. In particular, pyridyl groups on the surface of the latex particle stabilized the catalyst system probably by trapping trimethylaluminium. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3103–3113, 2006
Cationic photopolymerization of alkyl glycidyl ethers
Authors: Crivello James V.
Published: March 2006

An investigation of the photoactivated cationic ring‐opening frontal polymerizations of a series of alkyl glycidyl ethers was carried out with the aid of a novel technique, optical pyrometry. With this technique, the effects of various experimental parameters, such as the photoinitiator type and concentration, as well as the effects of the monomer structure on the frontal behavior of these monomers were examined. Upon irradiation with UV light, the photopolymerizations of many alkyl glycidyl ethers displayed a prominent induction period at room temperature as the result of the formation of long‐lived, relatively stable secondary oxonium ions. The input of only a small amount of thermal activation energy was required to induce the further reaction of these species with the consequent autoaccelerated exothermic ring‐opening polymerization. Photoactivated frontal polymerizations were observed for both mono‐ and polyfunctional alkyl glycidyl ether monomers. The ability of monomers to exhibit frontal behavior was found to be related to their ability to stabilize the secondary oxonium ion intermediates through hydrogen‐bonding effects. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3036–3052, 2006
De novo ligand design to an ensemble of protein structures
Authors: Todorov N.P. , Buenemann C.L. , Alberts I.L.
Published: March 2006

We describe a combinatorial method for de novo ligand design to an ensemble of receptor structures. Receptor conformations, protonation states, and structural water molecules are considered consistently within the framework of de novo ligand design. The method relies on Monte Carlo optimization to search the space of ligand structures, conformations, and rigid‐body movements as well as receptor models. The method is applied to an ensemble of HIV protease and human collagenase receptor models. Ligand structures generated de novo exhibit the correct hydrogen‐bonding pattern in the core of the active site, with hydrophobic groups extending into the receptor S1 and S1′ pocket space. Furthermore, it is shown that known ligands are recovered in the correct binding mode and in the native, most tightly binding receptor model. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Analysis and prediction of helix–helix interactions in membrane channels and transporters
Authors: Hildebrand Peter Werner , Lorenzen Stephan , Goede Andrean , Preissner Robert
Published: March 2006

Membrane proteins span a large variety of different functions such as cell‐surface receptors, redox proteins, ion channels, and transporters. Proteins with functional pores show different characteristics of helix–helix packing as other helical membrane proteins. We found that the helix–helix contacts of 13 nonhomologous high‐resolution structures of membrane channels and transporters are mainly accomplished by weakly polar amino acids (G > S > T > F) that preferably create contacts every fourth residue, typical for right‐handed helix crossings. There is a strong correlation between the now available biological hydrophobicity scale and the propensities of the weakly polar and hydrophobic residues to be buried at helix–helix interfaces or to be exposed to the lipids in membrane channels and transporters. The polar residues, however, make no major contribution towards the packing of their transmembrane helices, and are therefore subsumed to be primarily exposed to the polar milieu during the folding process. The contact formation of membrane channels and transporters is therefore ruled by the solubility of the residues, which we suppose to be the driving force for the assembly of their transmembrane helices. By contrast, in 14 nonhomologous high‐resolution structures of other membrane protein coils, also large and polar amino acids (D > S > M > Q) create characteristic contacts every 3.5th residues, which is a signature for left‐handed helix crossings. Accordingly, it seems that dependent on the function, different concepts of folding and stabilization are realized for helical membrane proteins. Using a sequence‐based matrix prediction method these differences are exploited to improve the prediction of buried and exposed residues of transmembrane helices significantly. When the sequence motifs typical for membrane channels and transporters were applied for the prediction of helix–helix contacts the quality of prediction rises by 16% to an average value of 76%, compared to the same approach when only single amino acid positions are taken into account. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Specific DNA binding by the homeodomain Nkx2.5(C56S): Detection of impaired DNA or unfolded protein by isothermal titration calorimetry
Authors: Fodor Elfrieda , Ginsburg Ann
Published: March 2006

Titrations of specific 18‐bp duplex DNA with the cardiac‐specific homeodomain Nkx2.5(C56S) have utilized an ultrasensitive isothermal titration calorimeter (ITC). As the free DNA nears depletion, we observe large apparent decreases in the binding enthalpy when the DNA is impaired or when the temperature is sufficiently high to produce some unfolding of the free protein. Either effect can be attributed to refolding of the biopolymer that occurs as a result of stabilization due to the large favorable change in free energy on the homeodomain binding to DNA (−49.4 kJ/mol at 298 K). In either case, thermodynamic parameters obtained in such ITC experiments are unreliable. By using a lower temperature (85 vs. 95°C) during the annealing of complementary DNA strands, damage of the 18‐bp duplex DNA (Tm = 72°C) is avoided, and titrations with the homeodomain are normal at temperatures from 10 to 40°C when >95% of the protein is folded. Under the latter conditions, the heat capacity plot is linear with a ΔCp value of −0.80 ± 0.03 kJ K−1 mol−1, which is more negative than that calculated from the burial of solvent accessible surface areas (−0.64 ± 0.05 kJ K−1 mol−1), consistent with water structures being at the protein–DNA interfaces. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Accessibility of tobacco lipid transfer protein cavity revealed by15N NMR relaxation studies and molecular dynamics simulations
Authors: Da Silva Pedro , Landon Céline , Beltoise Romain , Ponchet Michel , Vovelle Françoise
Published: March 2006

Plant LTP1 are small helical proteins stabilized by four disulfide bridges and are characterized by the presence of an internal cavity, in which various hydrophobic ligands can be inserted. Recently, we have determined the solution structure of the recombinant tobacco LTP1_1. Unexpectedly, despite a global fold very similar to the structures already known for cereal seed LTP1, its binding properties are different: Tobacco LTP1_1 is able to bind only one monoacylated lipid, whereas cereal LTP1 can bind either one or two. The 3D structure of tobacco LTP1_1 revealed the presence of a hydrophobic cluster, not observed on cereal LTP1 structures, which may hinder one of the two entrances of the cavity defined for wheat LTP1. To better understand the mechanism of lipid entrance for tobacco LTP1_1 and to define the regions of the protein monitoring the accessibility of the cavity, we have complemented our structural data by the study of the internal dynamics of tobacco LTP1_1, using15N magnetic relaxation rate data and MD simulations at room and high temperatures. This work allowed us to define two regions of the protein experiencing the largest motions. These two regions delineate a portal that opens up during the simulation constituting a unique entrance of the hydrophobic cavity, in contrast with wheat LTP1 where two routes were detected. The hydrophobic interactions resulting from a few point mutations are strong enough to completely block the second portal so that the accessibility of the cavity is restricted to one entrance, explaining why this particular LTP1 binds only one lipid molecule. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Influence of metal salts on the photodegradation of imazapyr, an imidazolinone pesticide
Authors: Quivet Etienne , Faure René , Georges Joseph , Paıssé Jean‐Olivier , Lantéri Pierre
Published: March 2006

The behaviour of imazapyr (2‐(4‐isopropyl‐4‐methyl‐5‐oxo‐2‐imidazolin‐2‐yl)nicotinic acid), a broad spectrum herbicide of the imidazolinone family, has been studied under UV radiation in the presence of metal salts. Complexation interactions between imazapyr and metal ions decreased imazapyr photolysis. A chemometric study compared the photodegradation of imazapyr in aqueous solutions in the presence of Na+, Ca2+ or Cu2+ and their concomitant anionic species (Cl−, NO3−) at various pesticide/metal ion molar ratios. The study showed the major role of metal ions in the degradation of imazapyr and its main photoproducts. The molecules were strongly stabilised on complexation with metal ions, leading to an increase in persistence of the pesticide. Copyright © 2006 Society of Chemical Industry
Effects of Lagrangian multipliers on SWCNT in real space
Authors: Sünel N. , RIzaoǧlu E. , Harigaya K. , Özsoy O.
Published: March 2006

Electronic properties, band‐width, band gap, and van Hove singularities of (3,0), (4,0), and (9,0) zigzag nanotubes are investigated comparatively in the Harigaya model and a toy model, including the contributions of bonds of different types to the SSH Hamiltonian differently. Optical transition frequencies are calculated. In this way, an experimental correlation between the two models is achieved. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Theoretical study of the red‐ and blue‐shifted hydrogen bonds of nitroxyl and acetylene dimers
Authors: Liu Ying , Liu Wenqing , Yang Yong , Liu Jianguo
Published: March 2006

Ab initio molecular orbital and density functional theory (DFT) in conjunction with different basis sets calculations were performed to study the CH…O red‐shifted and NH…π blue‐shifted hydrogen bonds in HNOC2H2dimers. The geometric structures, vibrational frequencies and interaction energies were calculated by both standard and counterpoise (CP)‐corrected methods. In addition, the G3B3 method was employed to calculate the interaction energies. The topological and natural bond orbital (NBO) analysis were investigated the origin of NH…π blue‐shifted hydrogen bond. From the NBO analysis, the electron density decrease in the σ* (NH) is due to the significant electron density redistribution effect. The blue shifts of the NH stretching frequency are attributed to a cooperative effect between the rehybridization and electron density redistribution. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
O deficiency in the rutile TiO2(110) surface: Ab initio quantum chemical investigation of the electronic properties
Authors: Von Oertzen G. U. , Gerson A. R.
Published: March 2006

The (110) surface of rutile TiO2(110) has been modeled using a density functional theory (DFT) plane‐wave pseudo‐potential method (CASTEP). In this study, 6 and 9 atomic‐layer slabs have been examined. The stoichiometric surface converges to a low‐spin solution in both cases with a density of states (DOS) similar to that for the bulk. O deficiencies are introduced by the removal of neutral O atoms thus leaving a neutral model with a surfeit of 2 e−per vacancy. This results in the partial filling of the Ti t2gconduction band orbitals and a compensatory shift in the Fermi level. The reduced surface converges to a high‐spin solution in all cases, with the excess spin located within the previously unoccupied Ti t2gorbitals. Removal of the bridging surface O atoms results in an excess spin of 2 electrons per unit cell with approximately one‐half that for removal of in‐plane surface O atoms and subsurface O atoms. The removal of O atoms from the surface leads to an increase of the band gap, with the largest increase due to the removal of in‐plane 3‐fold coordinated surface O atoms, and the smallest one due to the removal of subsurface O atoms. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
High‐Speed Separation and Size Characterization of Wheat and Barley Starch Granules by Lift‐Hyperlayer Asymmetrical Flow Field‐Flow Fractionation in Synergy with SPLITT Fractionation
Authors: Contado Catia , Wahlund Karl‐Gustav
Published: March 2006

The complementary employment of two separation techniques, one analytical‐scale, the other preparative‐scale, i.e. the lift‐hyperlayer asymmetrical flow field‐flow fractionation (AsyFlFFF) and the split flow‐thin cell (SPLITT) is presented for the first time as a methodology to size‐separate and rapidly characterize starch granules of different botanical origins. Very rapid separation and size characterization is achieved by AsyFlFFF and the techniques are mutually used to characterize and confirm data produced by the other. Light microscopy (LM) was used to test the quality of the performed SPLITT separations and consequently to evaluate the AsyFlFFF results. The procedure was applied to wheat and barley starch.
Book Reviews: Starch Derivatization. Fascinating and Unique Industrial Opportunities By K. F. Gottlieb and A. Capelle
Authors: Bergthaller W.
Published: March 2006

No abstracts.
Towards a tribological reference test – fretting test?
Authors: Klaffke D.
Published: March 2006

Reference materials are in vogue. Reference methods for tribotesting are not available on a broad scale. Meaningful test methods working with simple specimens are of great interest for the calibration of results of tribological laboratory tests and also for the comparison of results from different sources. Gross slip fretting tests were performed at room temperature with a ball‐on‐flat configuration, using bearing steel (100Cr6, AISI 52100) easily available world‐wide. The scatter of friction and wear quantities was evaluated for tests with three different stroke values. In order to determine the effect of relative humidity (RH) on friction and wear results additional tests were performed in dry air and in moist air. The different methods of describing fretting results are discussed and recommendations are derived for the meaningful quantitative description of friction and wear results. On the basis of influence of stroke and RH on friction and wear results, proposals are given for the use of a fretting test as a reference procedure. Copyright © 2006 John Wiley & Sons, Ltd.
Thermally activated phenomena in nanoscopic sliding friction
Authors: Gnecco E. , Riedo E. , Bennewitz R. , Meyer E. , Brune H.
Published: March 2006

The role of thermal activation for a nanoasperity sliding on a flat surface with low speed is discussed. If the asperity slides in a vacuum, thermal vibrations may excite slipping from an equilibrium position to the next one along the sliding path. This effect is reduced if the velocity increases and leads to a logarithmic increase of friction with the sliding velocity. This is not always the case in a humid environment, where the formation of capillaries between tip and surface acts as an obstacle for thermally activated jumps. Depending on the wettability of the surface, different behaviors are observed. Copyright © 2006 John Wiley & Sons, Ltd.
Microtribology of silicon, oxide, and carbide surfaces
Authors: Ahmed S.I.‐U. , Bregliozzi G. , Haefke H.
Published: March 2006

This paper presents an overview of the microtribological properties of silicon oxide, sapphire, and titanium carbide surfaces as well as a self‐assembled monolayer with respect to their application in microsystems. Testing was performed with a reciprocating microtribometer with normal loads in the micronewton to millinewton range. Silicon and titanium carbide balls were used as counterbodies. For silicon oxide, sapphire and a perfluorodecyltrichlorosilane self‐assembled monolayer (FDTS), the microfriction corresponds to the water contact angle when the smoother titanium carbide ball or the relatively rougher silicon ball was used as a counterbody. Microfriction measurements performed on tribopairs of the same material, but having different roughnesses, showed that the friction of the rougher tribopairs is lower than that of the smoother ones. Interestingly, in the microforce regime, reduction in friction was significant and almost as much as when hydrophobic self‐assembled monolayers are applied on smooth surfaces. This investigation showed that comparative microtribological investigations between different material systems can be very challenging due to the fact that comparable roughness values on samples and countersamples are difficult to realize. Copyright © 2006 John Wiley & Sons, Ltd.
Microtribological behaviour of thin DLC films using different testing methods
Authors: Bandorf R. , Lüthje H. , Staedler T.
Published: March 2006

To enhance the lifetime and reliability of microcomponents, thin microtribological films are applied to microparts. With reduction of the component size, investigation methods for tribological testing must be adapted. This paper studies the microtribological behaviour of thin diamond‐like carbon (DLC) films using different testing methods. To tie in with macroscopic results, to determine friction we used the well‐known pin‐on‐disc test with spherical surfaces of 10 mm diameter under a typical load of 3 N. For investigations of the behaviour under single asperity contact, Atomic Force Microscope (AFM) methods with applied loads of a few hundred micronewtons were used. Investigations on thin DLC films showed that the friction coefficient under single asperity contact is strongly dependent on the applied load and the resulting contact area. Especially for thin films (up to a few hundred nanometres) the friction coefficient is influenced by the substrate material. With decreasing substrate Young's modulus the friction coefficient also decreases. On the other hand, an increase in the abrasive wear resistance was observed using soft substrate materials. In this paper we show that the friction coefficient was also reduced by a simple surface structure. For investigations we used photolithography to create concentric circles in different substrates. This resulted in a behaviour like riding on rails for the pin‐on‐disc test. Depending on the tribological pairing the friction coefficient was reduced to more than 50% of the original value. Copyright © 2006 John Wiley & Sons, Ltd.
Robust multi‐model control of an autonomous wind power system
Authors: Cutululis Nicolas Antonio , Ceanga Emil , Hansen Anca Daniela , Sørensen Poul
Published: March 2006

This article presents a robust multi‐model control structure for a wind power system that uses a variable speed wind turbine (VSWT) driving a permanent magnet synchronous generator (PMSG) connected to a local grid. The control problem consists in maximizing the energy captured from the wind for varying wind speeds. The VSWT‐PMSG linearized model analysis reveals the resonant nature of its dynamic at points on the optimal regimes characteristic (ORC). The natural frequency of the system and the damping factor are strongly dependent on the operating point on the ORC. Under these circumstances a robust multi‐model control structure is designed. The simulation results prove the viability of the proposed control structure. Copyright © 2006 John Wiley & Sons, Ltd.
Using airborne and satellite SAR for wake mapping offshore
Authors: Christiansen Merete B. , Hasager Charlotte B.
Published: March 2006

Offshore wind energy is progressing rapidly around Europe. One of the latest initiatives is the installation of multiple wind farms in clusters to share cables and maintenance costs and to fully exploit premium wind resource sites. For siting of multiple nearby wind farms, the wind turbine wake effect must be considered. Synthetic aperture radar (SAR) is an imaging remote sensing technique which offers a unique opportunity to describe spatial variations of wind speed offshore. For the first time an airborne SAR instrument was used for data acquisition over a large offshore wind farm. The aim was to identify the turbine wake effect from SAR‐derived wind speed maps as a downstream region of reduced wind speed. The aircraft SAR campaign was conducted on 12 October 2003 over the wind farm at Horns Rev in the North Sea. Nearly simultaneous measurements were acquired over the area by the SAR on board the ERS‐2 satellite. In addition, meteorological data were collected. Both aircraft and satellite SAR‐derived wind speed maps showed significant velocity deficits downstream of the wind farm. Wind speed maps retrieved from aircraft SAR suggested deficits of up to 20% downstream of the last turbine, whereas satellite SAR‐derived maps showed deficits of the order of 10%. The difference originated partly from the two different reference methods used for normalization of measured wind speeds. The detected region of reduced wind speed had the same width as the wind turbine array, indicating a low degree of horizontal wake dispersion. The downstream wake extent was approximately 10 km, which corresponds well with results from previous studies and with wake model predictions. Copyright © 2006 John Wiley & Sons, Ltd.
Intraoperative Jugular Venous Sampling Aids Detection of an Undescended Parathyroid Adenoma
Authors: Lee Lawrence S. , Canter Robert J. , Fraker Douglas L.
Published: March 2006

Introduction

A missed parathyroid adenoma is an important cause of persistent or recurrent primary hyperparathyroidism. Despite the widespread use of preoperative localizing tests and the advent of the rapid intact blood parathyroid hormone assay (iPTH), difficult operative cases are encountered when abnormal parathyroid glands cannot be identified.

Methods

Over a 5‐year period, 466 neck explorations were performed for primary hyperparathyroidism. This retrospective report describes the use of intraoperative jugular venous sampling to locate and remove successfully undescended parathyroid adenomas in three patients.

Results

Intraoperative jugular venous sampling for iPTH analysis was performed when a thorough neck exploration in combination with peripheral iPTH failed to reveal a source of hyperparathyroidism in patients with biochemically confirmed hyperparathyroidism. In all patients, a two‐ to fourfold iPTH gradient was observed between the affected and unaffected sides, and an undescended adenoma was located near the carotid bifurcation.

Conclusions

Intraoperative jugular venous sampling with iPTH analysis may be a useful technique for successfully detecting an undescended adenoma when other, more routine measures have failed.
Islet Hyperplasia in Adults: Challenge to Preoperatively Diagnose Non‐Insulinoma Pancreatogenic Hypoglycemia Syndrome
Authors: Starke Achim , Saddig Christiane , Kirch Barbara , Tschahargane Cyrus , Goretzki Peter
Published: March 2006

Background

Pancreatic hyperfunctional islet hyperplasia in adults has been more and more frequently described in the literature. Postprandial neuroglycopenia, a negative normal fasting test, negative pancreatic imaging results, and positive intra‐arterial calcium stimulation of serum insulin are characteristic. In affected patients the term non‐insulinoma pancreatogenic hypoglycemia syndrome (NIPHS) was proposed.

Materials and Methods/Patients

We also encountered fasting hypoglycemia in such patients and therefore evaluated clinical and biochemical data in patients with NIPHS (n = 11), patients with insulinoma (n = 70), and patients in whom hypoglycemia was ruled out (n = 70).

Results

Patients with NIPHS were younger (median age: 41 years; range: 18–66) and mostly non‐obese (median body mass index/BMI: 22.2 kg/m2; range: 19–39) compared with patients with an insulinoma (median age: 50 years; median: BMI 26.1 kg/m2). During an oral glucose tolerance test (OGTT) followed by a standard fasting test, neuroglycopenia was observed postprandially with a mean minimal blood glucose level of 36 ± 9 mg/dl in 7 out of 11 patients. Spontaneous hypoglycemia during the fast was 38 ± 5 mg/dl in 8 out of 11 patients. The corresponding insulin levels were 9.2 ± 9.8 mU/l (OGTT) and 6.8 ± 5.4 mU/l (fasting), significantly lower than in patients with insulinoma (P < 0.001), but not different from patients without hypoglycemia (P = 0.05). After pancreatic resection 8 patients (73%) were cured with enduring euglycemia. Pathohistological islet abnormalities with hyperplasia, hypertrophy, and microadenomatosis were confirmed in all patients.

Conclusion

In patients with postprandial and/or fasting neuroglycopenia NIPHS may be suspected when insulin levels are low but inadequately suppressed and localization studies failed to show a distinct pancreatic tumor.
Stem cells and their potential relevance to paediatric cardiology
Authors: Pillekamp Frank , Reppel Michael , Brockmeier Konrad , Hescheler Jürgen
Published: March 2006

Basic scientists, as well as cardiologists, are caught by the idea of curing ischaemic heart disease with cardiac progenitor or stem cells. This short review provides an overview of our current knowledge on the potential use of stem cells for cardiac disease. Since, in infants and children, aetiologies and pathomechanisms of critical cardiac disease are fundamentally different from those in adults, we will also address the question as to whether such young patients could be a therapeutic target at all, and in which respect it may be necessary to view treatment with stem cells from a different stance in the developing organism.
Transesophageal 3-dimensional versus cross-sectional echocardiographic assessment of the volume of the right ventricle in children with atrial septal defects
Authors: Heusch Andreas , Lawrenz Wolfgang , Olivier Margarete , Schmidt Klaus Georg
Published: March 2006

The study was designed to investigate the value of assessing right ventricular volume by transoesophageal 3-dimensional echocardiographic techniques compared with the standard transoesophageal cross-sectional approach. Echocardiography was performed using a multiplane probe. The 3-dimensional data sets were reconstructed after electrocardiographic and respiratory gated scanning, calculating the 3-dimensional volumes by the method of multiple slices. Cross-sectional determination of volume was performed using a modified area-length method, and the biplane multiple slice method following Simpson's rule. We studied 15 patients, with ages ranging from 6 to19 years, and body surface areas from 1.1 to 1.67 square metres. It proved possible top determine volumes with both methods in all patients. As determined by 3-dimensional echo, volumes were greater, being 113.0 plus or minus 61.2 millilitres at end-systole, and 61.7 plus or minus 36 millilitres at end-diastole, than those calculated from cross-sectional images using Simpson's rule, which gave values of 92.5 plus or minus 52 millilitres, and 41.3 plus or minus 22 millilitres. Compared to the values obtained using the area-length method, at 116.9 plus or minus 61 millilitres, and 60.3 plus or minus 30 millilitres, there were only small differences at end-systole, with a bias of 1.4, and limits of agreement of 20.9 millilitres, as well as at end-diastole, when bias was minus 3.8, and limits of agreement 22.3 millilitres. Correlation was also good, with coefficients of 0.93, and 0.91, respectively. The mean difference between the volumes by 3-dimensional acquisition and the multiple slice method was larger, with higher limits of agreement, at end-diastole showing bias of 20.5, and limits of agreement of 30.1 millilitres, and for end-systole bias of 20.4, and limits of agreement of 32.2 millilitres. Our data confirm that cross-sectional echocardiographic assessment of right ventricular volumes in children with atrial septal defects is quick, and reasonably reliable in clinical practice when employing the area-length method.
Clinical and echocardiographic features of Ebstein's malformation in Sudanese patients
Authors: Ali Sulafa K. M. , Nimeri Nuha A. G. M.
Published: March 2006

Ebstein's malformation is a rare congenital cardiac malformation, accounting for about 0.5% of all congenital cardiac lesions. We report our experience with the anomaly as encountered at the Sudan Heart Centre from July 2004 to April 2005. Diagnosis was based on the echocardiographic demonstration of displacement of the septal leaflet of the tricuspid valve towards the ventricular apex by greater than 8 millimetres per metre squared. Results: In a period of 10 months, we identified 12 patients with the malformation, this number constituting 2% of all patients seen with congenital cardiac disease. The age ranged from 2 weeks to 35 years. Of the patients, half were asymptomatic, while the other half presented with congestive cardiac failure, 4 of these having cyanosis in addition to heart failure. Associated diseases included chronic renal failure, impaired hearing, stunted growth, and developmental delay. Electrocardiographic abnormalities included peaked and tall P waves, seen in four-fifths, an Rsr pattern, first degree atrioventricular block, atrial fibrillation, and Wolf–Parkinson–White syndrome, including the Mahaim pattern of pre-excitation. Associated abnormalities diagnosed echocardiographically included atrial septal defects, prolapse of the leaflets of the mitral valve, left ventricular dysfunction, atrial septal aneurysm, pulmonary valvar stenosis, and pericardial effusion. Conclusions: Ebstein's malformation was seen four times more frequently at the Sudan Heart Centre when compared to the average frequency reported in the Western literature. Many of the associated diseases encountered in Sudan had not previously been reported.
The development of a new measure of quality of life for children with congenital cardiac disease
Authors: Macran Susan , Birks Yvonne , Parsons Jonathan , Sloper Patricia , Hardman Geoff , Kind Paul , van Doorn Carin , Thompson David , Lewin Robert
Published: March 2006

The purpose of the study was to develop a questionnaire measuring health-related R1 quality of life for children and adolescents with congenital heart disease, the ConQol, that would have both clinical and research applications. We describe here the process of construction of a questionnaire, the piloting and the development of a weighted scoring system, and data on the psychometric performance of the measure in a sample of 640 children and young people recruited via 6 regional centres for paediatric cardiology from across the United Kingdom. The ConQol has two versions, one designed for children aged from 8 to 11 years, and the other for young people aged from 12 to 16 years. Initial findings suggest that it is a valid and reliable instrument, is acceptable to respondents, and is simple to administer in both a research and clinical context.
Anomalous connection of the right superior caval vein to the morphologically left atrium
Authors: Gorenflo Matthias , Sebening Christian , Ulmer Herbert E.
Published: March 2006

Anomalous drainage of the right superior caval vein into the morphologically left atrium as an isolated cardiac malformation is a rare anomaly. Most patients present with cyanosis. Thus far, about 20 cases have been reported in the literature. We report a case of cyanosis due to this malformation in a male neonate, which was complicated by the meconium aspiration syndrome. The malformation was diagnosed by echocardiography and cardiac catheterization. Surgery resulted in complete recovery.
Spatially correlated rainfall in a protective irrigation system
Authors: JANMAAT JOHANNUS A.
Published: March 2006

Allowing water to be traded in an irrigation system with de facto riparian rights can increase the efficiency of water use. With irrigation supplementing uncertain rainfall, both supply and demand for water are uncertain. When rainfall events are positively correlated, water supply and demand movements are negatively correlated, causing large price fluctuations. Using a stylized two crop, two region irrigation system, numerical integration over a bivariate rainfall distribution is used to demonstrate the impact of varying rainfall correlation on water price, expected returns, and return variability. A spot market for water captures the majority of the returns to water rights transfers, relative to a complete market. This spot market results in higher returns and reduced return volatility for farmers in the water deficit region, while farmers in the water surplus region see greater returns but also greater return volatility.