bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural and luminescence properties of In‐rich InGaN layers grown on InN templates by RF‐MBE
Authors: Naoi H. , Kurouchi M. , Takado S. , Muto D. , Araki T. , Nanishi Y.
Published: November 2005

Structural and luminescence properties of In‐rich Inx Ga1−x N (0.71 ≤ x ≤ 1) layers are comprehensively studied. The layers were grown on (0001) sapphire substrates by radio‐frequency plasma‐assisted molecular‐beam epitaxy, employing two types of underlying structures: low‐temperature‐grown InN (LT‐InN) buffer layers and high‐temperature‐grown InN templates grown on LT‐InN buffer layers. The insertion of the InN templates has improved not only surface morphology but also both a ‐axis and c ‐axis orientations of In‐rich Inx Ga1−x N layers. In addition, by using InN templates of dramatically improved crystalline quality with the full width at half maximum of (0002) X‐ray rocking curves as narrow as 1 arcmin, which have been recently achieved by optimizing nitridation conditions of sapphire substrates, the crystalline quality of In0.8Ga0.2N layers was even further improved. On the other hand, however, photoluminescence (PL) line width showed no noticeable variation between the Inx Ga1−x N layers grown on InN templates and those on LT‐InN buffer layers. Possible factors that determine PL line width and compositional fluctuation of these In‐rich Inx Ga1−x N are discussed. Interference fringes of X‐ray diffraction (ω –2θ scan) have been observed from the high crystalline‐quality InN templates of the excellent c ‐axis orientation for the first time. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Continuous wave and time resolved spectroscopy of InAsN/GaAsN based quantum dots
Authors: Taliercio T. , Valvin P. , Intartaglia R. , Sallet V. , Harmand J. C. , Guillet T. , Lefebvre P. , Bretagnon T. , Gil B.
Published: November 2005

We present a study of the optical properties of quantum dots based on a new family of semiconductors: III–V dilute nitrides such as (In,Ga)(N,As). Continuous wave and time resolved photoluminescence (PL) experiments allowed us to evaluate the impact of N incorporation during the growth of InAs/GaAs quantum dots. Previous work [V. Sallet et al., to be submitted to J. Cryst. Growth (2005); O. Schumann et al., J. Appl. Phys. 96, 2832 (2004)] showed that increasing the flux of N atoms into the growth chamber modifies drastically the size of the dots which leads to a bimodal growth. Two populations of dots with different sizes appear. The quantum dot PL line broadens and a second PL line appears at higher energy. Time resolved PL allows us to identify the nature of this second PL line: second population of quantum dots. A second decay time is observed which we interpret as being the consequence of the perturbation of the electronic states of the quantum dots. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exciton dark states in the recombination kinetics of InAs quantum dots
Authors: Vinattieri Anna , Zamfirescu Marian , Gurioli Massimo , Colocci Marcello , Sanguinetti Stefano , Noetzel Richard
Published: November 2005

Time‐resolved photoluminescence experiments in high quality InAs/GaAs quantum dots clearly show the interplay between radiative recombination and thermalization processes. In particular from temperature dependent PL spectra, we prove that the carrier recombination dynamics is ruled by the thermal population in optically inactive exciton states, related to the population of the first excited hole levels. Moreover time‐resolved spectra do not show any relaxation bottleneck, indicating an efficient carrier capture and a fast energy relaxation of the photogenerated carriers. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of Ge nanowires grown on Si(100) and (111) substrates: Nanowire–substrate heterointerfaces
Authors: Kamenev B. V. , Sharma V. , Tsybeskov L. , Kamins T. I.
Published: November 2005

The cover picture of the present issue of physica status solidi (a) contains two scanning electron micrographs showing approximately 40 nm diameter Ge nanowires grown by the vapor–liquid–solid (VLS) technique on Si(100) (upper right figure) and Si(111) (lower left figure) substrates, respectively. The figures are provided by the authors T. I. Kamins (Hewlett‐Packard Laboratories) and L. Tsybeskov (New Jersey Institute of Technology).
Dipolar contribution to the birefringence and second‐order susceptibility of organic materials
Authors: Trivedi Rashmi , Sen Pratima , Sen Pranay K.
Published: November 2005

Incorporating the dipolar contribution and using density matrix analysis, the linear and nonlinear opti‐ cal susceptibilities are calculated in polar organic crystal. The dipolar contribution successfully explains the origin of ordinary and the extraordinary refractive indices of polar materials in the infrared regime. The results are applied to a sample of Urea. The calculated values of the refractive indices, hyperpolarizability and second‐order optical susceptibility are well in agreement with the experimentally reported values. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Local and general aspects of current profiles in quantum magnetotransport
Authors: Cresti Alessandro , Grosso Giuseppe , Pastori Parravicini Giuseppe
Published: November 2005

We present a formal and numerical analysis of current distribution through two‐dimensional electron gas systems threaded by a magnetic field. The nonequilibrium Keldysh formalism is elaborated into a procedure well suited to describe both local features of carrier flow and universal features connected to the spatial chirality produced by strong magnetic fields. The interplay between disorder and chirality is illustrated by numerical simulations of significant models. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Molecular Modeling of Meta II Rhodopsin
Authors: Ślusarz Rafał , Ślusarz Magdalena J. , Lammek Bernard , Ciarkowski Jerzy
Published: November 2005

A model believed to be representative for activated class A G protein‐coupled receptors is proposed. It consists of rhodopsin and the transducin α C‐terminal peptide [Gtα(338–350)] docked to it. The model utilizes the resolved interactions/distances, found to be essential in the activated rhodopsin (RD*) and the structure of Gtα(338–350) that is known to stabilize RD*. Long‐term molecular dynamics (14.8 ns) in fully hydrated lipid bilayer model is applied to the system to refine and verify conformational changes in rhodopsin itself and the structure of the complex. A concomitant role of Gtα and Gtγ C‐termini in stabilizing RD* could possibly be resolved assuming a receptor dimer as a requisite for G protein activation.
A new approach for the two‐electron cumulant in natural orbital functional theory
Authors: Piris Mario
Published: November 2005

The cumulant expansion gives rise to a useful decomposition of the two‐matrix D in which the pair correlated matrix (cumulant) is disconnected from the antisymmetric product of the one‐matrix Γ. A new explicit antisymmetric approach for the two‐particle cumulant matrix in terms of two symmetric matrices, Δ and Λ, as functionals of the occupation numbers is proposed for singlet ground states of closed‐shell systems. It produces a natural orbital functional that reduces to the exact expression for the total energy in two‐electron systems. The functional form of matrix Λ is readily generalized to any system with an even number of electrons. The diagonal elements of Δ equal the square of the occupation numbers, and the N‐representability positivity necessary conditions of the two‐matrix impose several bounds on the off‐diagonal elements of matrix Δ. The well‐known mean value theorem and the partial sum rule obtained for the off‐diagonal elements of Δ provide a prescription for deriving a practical functional. In particular, when the mean values {J} of the Coulomb interactions {Jij} for a given orbital i taking over all orbitals j ≠ i are assumed to be equal {Kii/2}, a functional close to self‐interaction‐corrected GU functional is obtained, but the two‐matrix fermionic antisymmetric holds. An additional term for the matrix elements of Λ between HF occupied orbitals is proposed to ensure a correct description of the occupation numbers for the lowest occupied levels. The functional is tested in fully variational finite basis set calculations of 57 molecules. It gives reasonable molecular energies at the equilibrium geometries. The calculated values of dipole moments are in good agreement with the available experimental data. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Density functional study of structural and electronic properties of AlnN (1 ≤ n ≤ 12) clusters
Authors: Guo Ling , Wu Hai‐Shun
Published: November 2005

Low‐lying equilibrium geometric structures of AlnN (n = 1–12) clusters obtained by an all‐electron linear combination of atomic orbital approach, within spin‐polarized density functional theory, are reported. The binding energy, dissociation energy, and stability of these clusters are studied within the local spin density approximation (LSDA) and the three‐parameter hybrid generalized gradient approximation (GGA) due to Becke–Lee–Yang–Parr (B3LYP). Ionization potentials, electron affinities, hardness, and static dipole polarizabilities are calculated for the ground‐state structures within the GGA. It is observed that symmetric structures with the nitrogen atom occupying the internal position are lowest‐energy geometries. Generalized gradient approximation extends bond lengths as compared with the LSDA lengths. The odd–even oscillations in the dissociation energy, the second differences in energy, the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) gaps, the ionization potential, the electron affinity, and the hardness are more pronounced within the GGA. The stability analysis based on the energies clearly shows the Al7N cluster to be endowed with special stability. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Ab initio study of Rg2I− (Rg = Ar, Kr, Xe)
Authors: Li X. , Zhao Y. , Jing X. , Liu F. , Hao F.
Published: November 2005

The equilibrium geometries, vibrational frequencies, and dissociation energies of rare gas iodine clusters Rg2I−(Rg = Ar, Kr, Xe) were calculated at the Hartree–Fock (HF), second‐order Møller–Plesset (MP2), the coupled cluster method with single and double excitation and a noniterative correction for triple excitations method [CCSD(T)] levels. The title species have bent C2v structure of about 60° angle. The electron correlation effects and relativistic effects on the geometry and stability were investigated at CCSD(T) level. Both effects stabilize title species. The calculated electron affinities are in good agreement with the experimental results available. The effect of high angular momentum functions (g and h) was studied. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Blue‐shifted and red‐shifted hydrogen bonds: Theoretical study of the CH3CHO· · ·HNO complexes
Authors: Yang Yong , Zhang Weijun , Gao Xiaoming
Published: November 2005

The blue‐shifted and red‐shifted H‐bonds have been studied in complexes CH3CHO…HNO. At the MP2/6‐31G(d), MP2/6‐31+G(d,p) MP2/6‐311++G(d,p), B3LYP/6‐31G(d), B3LYP/6‐31+G(d,p) and B3LYP/6‐311++G(d,p) levels, the geometric structures and vibrational frequencies of complexes CH3CHO…HNO are calculated by both standard and CP‐corrected methods, respectively. Complex A exhibits simultaneously red‐shifted CH…O and blue‐shifted NH…O H‐bonds. Complex B possesses simultaneously two blue‐shifted H‐bonds: CH…O and NH…O. From NBO analysis, it becomes evident that the red‐shifted CH…O H‐bond can be explained on the basis of the two opposite effects: hyperconjugation and rehybridization. The blue‐shifted CH…O H‐bond is a result of conjunct CH bond strengthening effects of the hyperconjugation and the rehybridization due to existence of the significant electron density redistribution effect. For the blue‐shifted NH…O H‐bonds, the hyperconjugation is inhibited due to existence of the electron density redistribution effect. The large blue shift of the NH stretching frequency is observed because the rehybridization dominates the hyperconjugation. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Simultaneous quantification of fludarabine and cyclophosphamide in human plasma by high‐performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry
Authors: Silvertand L. H. H. , Vazvaei F. , Weigl P. , Rosing H. , Hillebrand M. J. X. , van Maanen M. J. , Beijnen J. H.
Published: November 2005

Fludarabine and cyclophosphamide are anticancer agents mainly used in the treatment of hematologic malignancies. We have developed and validated an assay using high‐performance liquid chromatography (HPLC) coupled with electrospray ionization tandem mass spectrometry for the quantification of fludarabine in combination with cyclophosphamide in human heparin and human EDTA plasma. Sample pre‐treatment consisted of a protein precipitation with cold acetonitrile (−20°C) using 250 µL of plasma. Separation was performed on an Extend C18 column (150 × 2.1 mm i.d.; 5 µm) with a stepwise gradient using 1 mM ammonia solution and acetonitrile at a flow rate of 400 µL/min. The analytical run time was 12 min. The triple quadrupole mass spectrometer was operated in the positive ion mode and multiple reaction monitoring was used for drug quantification. The method was validated over a concentration range of 1 to 100 ng/mL for fludarabine and cyclophosphamide in human heparin and human EDTA plasma. The coefficients of variation were <13.9% for inter‐ and intra‐day precisions. Mean accuracies were also within the designated limits (±15%). The analytes were stable in plasma, processed extracts and in stock solution under all relevant conditions. Copyright © 2005 John Wiley & Sons, Ltd.
Mass spectrometric studies of the formation and reactivity of trans‐[PtCl2(Am)(piperidinopiperidine)] · HCl complexes with ubiquitin
Authors: Balter Liliana , Gibson Dan
Published: November 2005

trans‐[PtCl2(Am)(pip‐pip)] · HCl complexes, where Am = ammine, methylamine and dimethylamine, react with ubiquitin to form 1:1 covalent adducts. The platinum complexes bind exclusively to Met1 of ubiquitin forming trans‐[PtCl(S‐Met1‐Ub)(Am)(pip‐pip)] adducts. These adducts are reactive towards nucleophiles and react with deoxyguanosine (dGMP) to form the ternary trans‐[Pt(dGMP)(S‐Met1‐Ub) (Am)(pip‐pip)] complex which is stable in water and even in the presence of excess glutathione (GSH). Reaction of trans‐[PtCl(S‐Met1‐Ub)(Am)(pip‐pip)] with GSH resulted in the rapid formation of the ternary complex trans‐[Pt(GS)(S‐Met1‐Ub)(Am)(pip‐pip)] which was not stable and slowly lost the platinum moiety; after 7 days the platinum moiety was completely removed and the native ubiquitin was regenerated. Copyright © 2005 John Wiley & Sons, Ltd.
Rapid accurate mass desorption electrospray ionisation tandem mass spectrometry of pharmaceutical samples
Authors: Williams Jonathan P. , Scrivens James H.
Published: November 2005

Desorption electrospray ionisation (DESI) has been successfully combined with a hybrid quadrupole time‐of‐flight mass spectrometer to provide mass spectra and product ion mass spectra of active ingredients formulated in pharmaceutical tablets, gels and ointments. Accurate mass data has been obtained from the DESI mass spectra and of the product ion fragments of selected ions, greatly enhancing the selectivity and information content of the experiment. This accurate mass information only takes seconds to acquire since the DESI technique does not require any sample preparation or extraction prior to mass analysis. Copyright © 2005 John Wiley & Sons, Ltd.
A telerobotic haptic system for minimally invasive stereotactic neurosurgery
Authors: Rossi A , Trevisani A , Zanotto V
Published: November 2005

Medical robotics and computer assisted surgery are feasible and promising applications of robotic technology, whose main goals are surgical augmentation, information enhancement and improved surgical action. Neurosurgery probably presents the most major challenges, and can considerably benefit from the introduction of computers and robots to guide surgical procedures. This paper presents an innovative master‐slave haptic robotic system for minimally invasive neurosurgery, which can help surgeons overcome human shortcomings and perform more accurate, repeatable, and reliable stereotactic neurosurgery. The system, named LANS, consists of a slave mechatronic actuator and a haptic master. The slave is designed to move linearly a laser pointer, a biopsy needle or a low‐energy X‐ray emitter along a pre‐planned axis. The tool insertion into the brain is guided by the surgeon through the haptic master which also provides force feedback to the operator. Not only can the haptic master reproduce the contact force between the surgical tool and the treated tissue, but it can also produce virtual forces aimed at assisting surgeons during the operations. Experiments have been conducted to prove the soundness and accuracy of the overall system mechanical design and to assess the effectiveness of the control schemes synthesized for the master and the slave. Copyright © 2005 Robotic Publications Ltd.
Preoperative planning system for surgical robotics setup with kinematics and haptics
Authors: Hayashibe M , Suzuki N , Hashizume M , Kakeji Y , Konishi K , Suzuki S , Hattori A
Published: November 2005

Recently, some useful robotic surgical systems have been developed and applied in many surgical situations. Systems such as the da VinciTM surgical system of Intuitive Surgical Inc., which facilitates minimally invasive surgery with increased dexterity, are commercially available. Preoperative simulation and planning of surgical robot setups should accompany advanced robotic surgery if their advantages are to be further pursued. Feedback from the planning system will play an essential role in computer‐aided robotic surgery in addition to preoperative detailed geometric information from patient CT/MRI images. Surgical robot setup simulation systems for appropriate trocar site placement have been developed especially for abdominal surgery. The motion of the surgical robot can be simulated and rehearsed with kinematic constraints at the trocar site, and the inverse‐kinematics of the robot. Results from simulation using clinical patient data verify the effectiveness of the proposed system. Copyright © 2005 Robotic Publications Ltd.
Robotic microsurgical vasovasostomy and vasoepididymostomy in rats
Authors: Schiff J , Li P S , Goldstein M
Published: November 2005

Robotic and robotic assisted procedures are rapidly increasing in popularity amongst practicing surgeons and urologists. Robotic techniques are now commonly used to perform radical prostatectomies for prostate cancer and pyeloplasties for uretero‐pelvic junction obstruction. Other robotic procedures include robotic assisted coronary artery bypass and partial nephrectomies. We initially studied the da Vinci surgical robot in order to determine the feasibility of adapting the robot to microsurgical vasovasostomy and vasoepididymostomy. In this paper, we describe our experience in developing a set of practice exercises using the da Vinci robot to prepare for these microsurgical procedures. We also review the design and results of our studies of robotic microsurgical vasovasostomy and vasoepididymostomy in rats.

Finally, we discuss the potential future roles of robotic microsurgery in urology and surgery. Copyright © 2005 Robotic Publications Ltd.
Regular graphs whose subgraphs tend to be acyclic
Authors: Alon Noga , Bachmat Eitan
Published: November 2005

Motivated by a problem that arises in the study of mirrored storage systems, we describe, for any fixed ε, δ > 0, and any integer d ≥ 2, explicit or randomized constructions of d‐regular graphs on n > n0(ε, δ) vertices in which a random subgraph obtained by retaining each edge, randomly and independently, with probability
$\rho={1-\epsilon \over d-1}$, is acyclic with probability at least 1 − δ. On the other hand we show that for any d‐regular graph G on n > n1(ε, δ) vertices, a random subgraph of G obtained by retaining each edge, randomly and independently, with probability $\rho={1+\epsilon \over d-1}$, does contain a cycle with probability at least 1 − δ. The proofs combine probabilistic and combinatorial arguments, with number theoretic techniques. © 2005 Wiley Periodicals, Inc. Random Struct. Alg., 2006
The “physics” of capacity and backlog management in service and custom manufacturing supply chains
Authors: Anderson Edward G. , Morrice Douglas J. , Lundeen Gary
Published: November 2005

In this paper, we investigate the dynamic behavior of service supply chains in the presence of varying demand and information sharing. Each stage holds no finished goods inventory, rather only backlogs that can be managed solely by adjusting capacity. These conditions reflect the reality of many service (and custom manufacturing, such as capital equipment) supply chains. While there is a growing literature on finished goods inventory management in supply chains, relatively little research exists on managing capacity in the absence of finished goods inventory. To address this problem, we develop a capacity management model for a serial chain. At each stage in the supply chain, our model relates capacity, processing, backlog, and service delays to capture the aggregate dynamic interactions between the different stages. Using a system dynamics simulation model in an experimental design as well as a formal analysis of a simplified, yet representative, model using control theory and signal analysis techniques, we characterize the conditions under which a “bullwhip effect” (i.e., an increase in demand and backlog variability as one looks up the supply chain) can occur. We then study the impact of different management strategies and levels of information visibility on capacity and service delay variability in a two‐stage model.

Conventional wisdom, derived from studies of make‐to‐stock manufacturing supply chains, strongly supports lead‐time reduction in order to mitigate the bullwhip effect. We show that lead‐time reduction can exacerbate the bullwhip effect in a service or custom manufacturing setting if it is not carefully coordinated with capacity adjustment. In particular, lead‐time reduction generally reduces backlog variance locally but often increases backlog variances at higher stages. Further, sharing end‐customer demand reduces backlog variances as in inventory supply chains but over‐reliance on it relative to local information may actually increase demand variance at higher stages. Finally, we show that the natural tendency to pursue system‐wide process improvement by imposing uniform parameter targets across the supply chain exacerbates demand, capacity, and backlog variances at higher stages. Instead, we show that a superior policy is asymmetric, holding the bulk of system backlog at the stage closest to the point of end customer demand. Copyright © 2005 John Wiley & Sons, Ltd.
Segmented Pt/Ru, Pt/Ni, and Pt/RuNi Nanorods as Model Bifunctional Catalysts for Methanol Oxidation
Authors: Liu Fang , Lee Jim Yang , Zhou Wei Jiang
Published: November 2005

Five‐segment (Pt‐Ru‐Pt‐Ru‐Pt, Pt‐Ni‐Pt‐Ni‐Pt, and Pt‐RuNi‐Pt‐RuNi‐Pt) nanorods with the same overall rod length and the same total Pt segment length were prepared by sequential electrodeposition of the metals into the pores of commercially available anodic aluminum oxide (AAO) membranes. Field‐emission scanning electron microscopy (FESEM) showed that the nanorods were about 210 nm in diameter and about 1.5 μm in length. The alternating Pt and oxophilic metal(s) segments could be easily differentiated in backscattered‐electron images. X‐ray diffraction (XRD) analysis of the nanorods indicated that Pt and Ni were polycrystalline with fcc structures, Ru was hcp, and the co‐deposited RuNi adopted the nickel fcc structure with some negative shifts in the Bragg angles. The chemical states of Pt, Ru, and Ni on the nanorod surface were assayed by X‐ray photoelectron spectroscopy (XPS), and the presence of Pt0, PtII, PtIV, Ru0, RuVI, Ni0, and NiII was observed. The nanorods were catalytically active for the room‐temperature electrooxidation of methanol in acidic solutions. The relative rates of reaction showed the Pt‐RuNi pair sites as having the lowest overpotential to dissociate water, the highest catalytic activity in methanol oxidation, and the strongest CO‐tolerance in the potential window employed. The use of segmented nanorods with identifiable Pt–oxophilic metal(s) interfaces removes many of the ambiguities in the interpretation of experimental data from conventional alloy catalysts, thereby enabling a direct comparison of the activities of various types of pair sites in methanol oxidation.
Untersuchungen zu dynamischen Eigenschaften verkleideter Stahlskelette
Authors: Ciesielski Roman , Fiszer Paweł , Gwóźdź Marian
Published: November 2005

Im Rahmen eines Forschungsprojekts der Technischen Universität Krakau wurde die Wirkung von Verkleidungen auf Stahlskelette untersucht. Auf sechs verschiedene Arten wurde ein zweifeldriger Rahmen mit leichter Verkleidung versteift. Im vorliegenden Aufsatz werden die Ergebnisse des dynamischen Versuchsprogramms vorgestellt. Die Analyse der ermittelten dynamischen Eigenschaften zeigt, daß eine Verkleidung die dynamische Steifigkeit der Konstruktion und die Grundfrequenz ihrer Eigenschwingung im Vergleich zu einer Rahmenkonstruktion ohne Verkleidung erhöht.
Schweißen unter Betriebsbeanspruchung – Numerische und experimentelle Bestimmung des Temperaturfeldes beim Schweißen
Authors: Peil Udo , Wichers Michael
Published: November 2005

Die Bestimmung von Schweißeigenspannungen mittels experimenteller Meßverfahren gestattet nur eine punktuelle oder kleinflächige Aussage über die im Bauteil auftretende Spannungsverteilung. Aussagen über die zeitliche Veränderung sind nur im begrenzten Umfang möglich. Im nachstehenden Aufsatz sollen die Grundlagen für die numerische Bestimmung des transienten Temperaturfeldes in einem Bauteil durch den Wärmeeintrag infolge eines MAG‐Schweißlichtbogens vorgestellt werden. Die numerische Berechnung des transienten Temperaturfeldes dient als Grundlage einer strukturmechanischen Betrachtung zur Eigenspannungsermittlung mittels der FE‐Methode. Abschluß der Arbeit bildet ein Vergleich zwischen numerischer Simulation und Temperaturmessung an realen Schweißproben.
Assimilation, dissimilation, and detoxification of formaldehyde, a central metabolic intermediate of methylotrophic metabolism
Authors: Yurimoto Hiroya , Kato Nobuo , Sakai Yasuyoshi
Published: November 2005

Methanol is a valuable raw material used in the manufacture of useful chemicals as well as a potential source of energy to replace coal and petroleum. Biotechnological interest in the microbial utilization of methanol has increased because it is an ideal carbon source and can be produced from renewable biomass. Formaldehyde, a cytotoxic compound, is a central metabolic intermediate in methanol metabolism. Therefore, microorganisms utilizing methanol have adopted several metabolic strategies to cope with the toxicity of formaldehyde. Formaldehyde is initially detoxified through trapping by some cofactors, such as glutathione, mycothiol, tetrahydrofolate, and tetrahydromethanopterin, before being oxidized to CO2. Alternatively, free formaldehyde can be trapped by sugar phosphates as the first reaction in the C1 assimilation pathways: the xylulose monophosphate pathway for yeasts and the ribulose monophosphate (RuMP) pathway for bacteria. In yeasts, although formaldehyde generation and consumption takes place in the peroxisome, the cytosolic formaldehyde oxidation pathway also plays a role in formaldehyde detoxification as well as energy formation. The key enzymes of the RuMP pathway are found in a variety of microorganisms including bacteria and archaea. Regulation of the genes encoding these enzymes and their catalytic mechanisms depend on the physiological traits of these organisms during evolution. © 2005 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 5: 367–375; 2005: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20056
One course is not enough: Preservice elementary teachers' retention of improved views of nature of science
Authors: Akerson Valarie L. , Morrison Judith A. , McDuffie Amy Roth
Published: November 2005

This study examined the views, and the retention of these views, of 19 preservice elementary teachers as they learned about nature of science (NOS). The preservice teachers participated in a cohort group as they took a science methods course during which they received explicit reflective instruction in nature of science. Through Views of Nature of Science version B (VNOS‐B) surveys and interviews it was found that most preservice teachers held inadequate ideas of nature of science prior to instruction, but improved their views after one semester of instruction in the science methods course. However, 5 months after instruction, the graduate preservice teachers were again interviewed and it was found that several of the students reverted back to their earlier views. The results are interpreted through Perry's scheme, and implications and recommendations for elementary science teacher education are made. © 2005 Wiley Periodicals, Inc. J Res Sci Teach 43: 194–213, 2006
Analysis of internal drive train dynamics in a wind turbine
Authors: Peeters Joris L. M. , Vandepitte Dirk , Sas Paul
Published: November 2005

Three types of multibody models are presented for the investigation of the internal dynamics of a drive train in a wind turbine. The first approach is limited to the analysis of torsional vibrations only. Then a rigid multibody model is presented with special focus on the representation of the bearings and gears in the drive train. The generic model implementation can be used for parallel as well as planetary gear stages with both helical and spur gears. Examples for different gear stages describe the use of the presented formulations. Furthermore, the influence of the helix angle and the flexibility of the bearings on the results of eigenmode calculations are discussed. The eigenmodes of a planetary stage are classified as rotational, translational or out‐of‐plane modes. Thirdly, the extension to a flexible multibody model is presented as a method to include directly the drive train components' flexibilities. Finally, a comparison of two different modelling techniques is discussed for a wind turbine's drive train with a helical parallel gear stage and two planetary gear stages. In addition, the response calculation for a torque input at the generator demonstrates which eigenmodes can be excited through this path. Copyright © 2005 John Wiley & Sons, Ltd.
Activation of S phase checkpoint by cigarette smoke extract in Schizosaccharomyces pombe
Authors: Chaudhuri Santanu Pal , Sundaram Geetanjali , Bhattacharya Abhishek , Ray Partha , Ray Anirban , Chatterjee Indu Bhushan , Chattopadhyay Dhrubajyoti
Published: November 2005

Cigarette smoke has long been recognized as a major environmental pollutant that can cause significant damage to the cellular macromolecules. Although much is known about the types of damage, little is known about the cellular responses to the stress caused by cigarette smoke. We have used the fission yeast Schizosaccharomyces pombe to elucidate the overall cellular responses towards cigarette smoke. Here, we demonstrate that fission yeast cells exposed to aqueous extract of cigarette smoke exhibit cell cycle arrest and cell death in a dose‐dependent manner. Cigarette smoke treatment also results in accumulation of reactive oxygen species, unusual nuclear morphology and altered cellular structure. Our data further establish activation of the S phase checkpoint in cigarette smoke‐exposed Sz. pombe cells. The checkpoint proteins Rad3, Rad26, Rad17, Rad1, Hus1 and Cds1 play key roles in this process, as evidenced by cell survival and biochemical analysis, although another checkpoint protein, Rad9, seems to be less required. Our results also suggest involvement of the stress‐activated protein kinase Spc1/Sty1 and the bZIP transcription factors Atf1 and Pap1 in the cellular response towards cigarette smoke extract. These findings indicate activation of the critical S phase checkpoint and cell cycle arrest in Sz. pombe following CSE assault. Copyright © 2005 John Wiley & Sons, Ltd.
Taurine deficiency in maned wolves (Chrysocyon brachyurus) maintained on two diets manufactured for prevention of cystine urolithiasis
Authors: Childs‐Sanford Sara E. , Angel C. Roselina
Published: November 2005

This study assesses the long‐term effects of an experimental diet vs. a commercially available manufactured diet, intended to reduce clinical disease related to cystinuria, on the taurine status of captive maned wolves. For 13 weeks, two pairs of maned wolves were maintained on the commercially available maintenance diet, whereas two individually housed wolves were maintained on the experimental diet. All six wolves, at the beginning and at the end of the diet trial, had severely decreased plasma concentrations of taurine (as compared to the normal canine reference range of 60–120 nmol/ml) (National Research Council [2003] National Academies Press) with average taurine concentrations of 16 nmol/ml at the beginning of the study and 3 nmol/ml at the end of the study. There was no statistically significant difference in the taurine concentrations between animals on the maintenance vs. experimental diets. Both diets were supplemented subsequently with taurine at a concentration of 0.3%. All study animals were eventually switched to the taurine‐supplemented version of the commercially manufactured maintenance diet and subsequent samplings were carried out to monitor plasma taurine concentrations. A final sampling, carried out approximately 5 months after the initiation of taurine supplementation, showed an average taurine concentration within the target canine reference range (90.25 nmol/ml). There are numerous physiologic (e.g., possible unique metabolism and requirements for taurine in this species as compared to other canids) and dietary factors (e.g., effects of the types and concentrations of fiber and protein on nutrient availability, taurine metabolism, and enterohepatic circulation of taurine‐conjugated bile salts; impaired taurine synthesis secondary to low cysteine availability) that could be potential contributors to the development of taurine deficiency in the maned wolves in this study. Taurine supplementation should be considered in maned wolves maintained on diets intended for reduction of cystinuria‐related complications. Zoo Biol 0:1–14, 2005. © 2005 Wiley‐Liss, Inc.
Morphology of the blood cells from three species of wobbegong sharks (Orectolobus species) on the east coast of New South Wales
Authors: Old J.M. , Huveneers C.
Published: November 2005

This study is the first study to describe blood cell morphology, using light microscopy, for three species of wild‐caught wobbegong shark. Blood cell morphology was similar to that described previously in fish. Wobbegong sharks possess erythrocytes, at least three different morphological types of thrombocytes, lymphocytes, eosinophils, neutrophils, granuloblasts and monocytes. No basophils were observed in this study. Similarities and differences in morphological appearance of wobbegong shark blood cells compared to Chondrichthyes, teleosts and mammalian blood cells are discussed. Zoo Biol 0:1–10, 2005. © 2005 Wiley‐Liss, Inc.
Tolerance, optimum ranges, and ecological requirements of freshwater Ostracoda (Crustacea) in Lake Aladağ (Bolu, Turkey)
Authors: Yılmaz Faruk , Külköylüoğlu Okan
Published: November 2005

During monthly sampling from Lake Aladağ (Bolu, Turkey) between April 2003 and June 2004, nine ostracod taxa (Candona candida, Cypridopsis vidua, Darwinula stevensoni, Eucypris virens, Eucypris sp., Heterocypris sp., Limnocythere inopinata, Physocypria kraepelini, and Tonnacypris lutaria) were recorded from seven stations. Physocypria kraepelini was commonly found in the lake while the others were recorded in particular months. UPGMA analyses clustered three groups based on their occurrence. Accordingly, the occurrence of species (C. candida, E. virens, and T. lutaria) was positive and significantly related to each other. Two species, P. kraepelini and D. stevensoni, showed a significant positive relationship with electrical conductivity. A significant negative correlation was found between the occurrence of P. kraepelini and dissolved oxygen, while there was a significant positive correlation between the occurrence of P. kraepelini and turbidity. About 76% of the relationship between species and environmental factors was explained by the first two axes of canonical correspondence analyses (CCA). Temperature and dissolved oxygen were the two most important influences on the species assemblages. All species showed different but high optima and tolerance ranges, corresponding with their cosmopolitan characteristics. These responses may be related to unstable ecological characteristics of Lake Aladağ, which is often subjected to human activity.
Virtual temporal bone: Creation and application of a new computer‐based teaching tool
Authors: Mason Theodore P. , Applebaum Edward L. , Rasmussen Mary , Millman Alan , Evenhouse RAY , Panko Walter
Published: November 2005

The human temporal bone is a 3‐dimensionally complex anatomic region with many unique qualities that make anatomic teaching and learning difficult. Current teaching tools have proved only partially adequate for the needs of the aspiring otologic surgeon in learning this anatomy. We used a variety of computerized image processing and reconstruction techniques to reconstruct an anatomically accurate 3‐dimensional computer model of the human temporal bone from serial histologic sections. The model is viewed with a specialized visualization system that allows it to be manipulated easily in a stereoscopic virtual environment. The model may then be interactively studied from any viewpoint, greatly simplifying the task of conceptualizing and learning this anatomy. The system also provides for simultaneous computer networking that can bring distant participants into a single shared virtual teaching environment. Future directions of the project are discussed.
Effects of external beam radiation on the allograft dermal implant
Authors: Ibrahim Hani Z. , Kwiatkowski Terrance J. , Montone Kathleen T. , Evans Sydney M. , Rosenthal David , Chalian Ara A. , Staley Janet , Berlin Jesse , Wolf Patricia F. , Weber Randal S.
Published: November 2005

OBJECTIVE

The purpose of this study was to define the effects of external beam radiation (EBR) on AlloDerm (LifeCell Corp) through the analysis of graft thickness, fibroblast recellularization, and neo‐vascularization as a function of time.

METHODS AND MATERIAL

Thirty‐six male Sprague‐Dawley rats (n = 36) were randomly assigned to 1 of 4 groups (A, B, C, and D). AlloDerm was implanted subcutaneously into the hind legs of each rat, and 20 Gy of EBR was administered to one side. Grafts harvested 1, 2, 4, and 12 weeks after radiation were subjected to blinded histologic analysis.

RESULTS

In groups A, B, and C, the irradiated grafts showed a significant decrease in recellularization versus nonirradiated (P < 0.001). At 12 weeks (group D), recellularization equalized, but neovascularization was significantly less (P = 0.048) in the irradiated group. Graft thickness was unaffected.

CONCLUSIONS

In the rat model, EBR of the implanted AlloDerm graft hinders recellularization in the early posttreatment period. However, EBR did not adversely affect graft thickness, recellularization or ultimate graft survival.
Tumor grade, microvessel density, and activities of malate dehydrogenase, lactate dehydrogenase, and hexokinase in squamous cell carcinoma
Authors: Ross C. David , Gomaa Mohammed A. , Gillies Elizabeth , Juengel Randal , Medina Jesus E.
Published: November 2005

Squamous cell carcinomas were evaluated with respect to tumor differentiation (through use of hematoxylin and eosin stain), microvessel density (through use of CD‐34 immunocytochemical stain), and magnitudes of malate dehydrogenase (MDH), hexokinase, and lactate dehydrogenase (LDH) enzyme activities. Direct correlations were found between tumor grade, MDH activity, and microves‐sel density. Direct correlations were also found between hexokinase activity and MDH activity and microvessel density. Inverse correlations were found between LDH activity and both tumor grade and MDH activity. These results suggest that the high rate of glucose utilization (indicated by hexokinase activity) found in more poorly differentiated tumors has a higher component of aerobic oxidative metabolism (indicated by MDH activity) and a relatively lower contribution from anaerobic metabolism (indicated by LDH activity) than do the rates found in more differentiated tumors. It is also suggested that as the glycolytic rate increases, more pyruvate goes into the Krebs cycle than into lactate. The availability of glucose‐derived pyruvate for oxidative metabolism would mean less of a dependency on glutamine as a carbon source in squamous cell carcinoma.
Frey's syndrome and parotidectomy flaps: A retrospective cohort study
Authors: Taylor S. Mark , Yoo John , Matthews T. Wayne , Lampe Howard B. , Trites John R. B.
Published: November 2005

Gustatory sweating, also known as Frey's syndrome, is a recognized phenomenon after parotidectomy. The incidence of clinically significant gustatory sweating may be dependent on the thickness of the skin flap that is elevated at the time of surgery. Dissection in the subcutaneous level or the deeper sub‐superficial musculoaponeurotic system level are 2 commonly used techniques in the operation. Twenty‐eight patients were prospectively evaluated for Frey's syndrome after superficial parotidectomy. Thirteen patients underwent subcutaneous and 15 patients sub‐superficial musculoaponeurotic system flap elevation. The overall incidence of gustatory sweating was determined, and a comparison of the two surgical techniques was assessed subjectively by patient interview‐questionnaire and objectively evaluated with starch‐iodine testing.
Bilateral simultaneous orbital decompression for Graves' orbitopathy with a combined endoscopic and Caldwell‐Luc approach
Authors: Rizk Samieh S. , Papageorge Ariadna , Liberatore Lisa A. , Sacks Evan H.
Published: November 2005

Graves' orbitopathy can lead to cosmetic deformity, orbital pain, and visual impairment. Surgical intervention can improve proptosis, cosmetic appearance of the eyelids, vision, and orbital pain with minimal morbidity. Ten patients with dysthyroid orbito‐pathy underwent concurrent bilateral orbital decompressions. Of these, 9 underwent simultaneous bilateral endoscopic and transantral decompressions, and 1 had only bilateral endoscopic decompressions. Medical management of keratopathy was attempted before surgery. All patients were previously treated with radioiodine and high‐dose corticosteroids, and 2 patients had prior low‐dose orbital irradiation. Preoperative and postoperative visual acuity, color vision testing, and measurement of proptosis were recorded for all patients. In addition, photographs and CT scans of the orbit and sinuses were done. After surgery, visual acuity improved in 8 patients and remained unchanged in 2 patients. Diplopia in the primary and downward gaze improved in 1 patient and remained unchanged in the 3 others who had it before surgery. Color vision deficits in the blue/yellow range were present in 8 patients before surgery and all reversed within 2 weeks after surgery. Proptosis decreased by an average of 4.83 mm (range 4‐7 mm) in patients undergoing the combined decompression and decreased by 4 mm in the 1 patient who had the endoscopic decompression only. Ethmoid sinusitis developed in 1 patient but resolved with oral antibiotics, and another patient had an asymmetric result requiring additional unilateral surgery, which corrected the asymmetry. Overall, this approach avoids external incisions and allows excellent visualization in the regions of the orbital apex and ethmoid roof, facilitating maximal decompression without the increased risk of bleeding or visual disturbances.
Outcomes of septoplasty
Authors: Siegel Noah S. , Gliklich Richard E. , Taghizadeh Farhan , Chang Yuchiao
Published: November 2005

A prospective nonrandomized study of consecutive patients presenting to the Massachusetts Eye and Ear Infirmary for septoplasty was conducted to evaluate patient‐based outcome. Patients received statistically validated measures of general health status (Short Form‐12) and nasal specific health (Nasal Health Survey) before and 6 and 12 months after surgery. Multiple perioperative patient‐ and surgeon‐dependent treatment variables were also evaluated to determine the impact on outcome. A total of 161 patients were entered into the study, and 93 were available for statistical analysis. At 9 months the mean follow‐up (range 6‐12 months), both symptom and medication subscores of the Nasal Health Survey, and the total score demonstrated significant improvement (P < 0.05); 71% of patients had clinically significant improvement as determined by at least a 50% decrease in duration of nasal symptoms. Measures of general health did not differ significantly from normative values at baseline and did not change after surgical intervention. Predictor analysis revealed that female gender and a history of previous nasal surgery predicted worse outcome.
Oral appliances for the treatment of snoring and obstructive sleep apnea
Authors: Schoem Scott R.
Published: November 2005

Oral appliances have been used by dentists for several decades to treat snoring and obstructive sleep apnea. Although these devices are regulated by the Food and Drug Administration, most have undergone only sparse clinical testing for efficacy and safety. Most otolaryngologists are not well‐versed in their applicability as treatment options. This review summarizes the historical development of oral appliances, the types of available devices, the current literature regarding devices, and pertinent regulatory issues as they relate to the ongoing debate over appliance use and potential misuse.