bluuebunny/crossref_metadata_2025 huggingface dataset:
Oligopeptides as catalysts for asymmetric epoxidation
Authors: Kelly David R. , Roberts Stanley M.
Published: September 2005

Oligopeptides are versatile catalysts for the enantioselective epoxidation of electron deficient alkenes, (e.g. α,β‐unsaturated ketones) with alkaline hydrogen peroxide. This review describes optimisation of the catalyst, substrate range, synthetic applications of the products and rationalisation of the stereoselectivity by an active site model. © 2005 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 84: 74–89, 2006

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Robust scale‐up of dead end filtration: Impact of filter fouling mechanisms and flow distribution
Authors: Laska Michael E. , Brooks Ralph P. , Gayton Marshall , Pujar Narahari S.
Published: September 2005

Robust design of a dead end filtration step and the resulting performance at manufacturing scale relies on laboratory data collected with small filter units. During process development it is important to characterize and understand the filter fouling mechanisms of the process streams so that an accurate assessment can be made of the filter area required at manufacturing scale. Successful scale‐up also requires integration of the lab‐scale filtration data with an understanding of flow characteristics in the full‐scale filtration equipment. A case study is presented on the development and scale‐up of a depth filtration step used in a 2nd generation polysaccharide vaccine manufacturing process. The effect of operating parameters on filter performance was experimentally characterized for a diverse set of process streams. Filter capacity was significantly reduced when operating at low fluxes, caused by both low filtration pressure and high stream viscosity. The effect of flux on filter capacity could be explained for a variety of diverse streams by a single mechanistic model of filter fouling. To complement the laboratory filtration data, the fluid flow and distribution characteristics in manufacturing‐scale filtration equipment were carefully evaluated. This analysis identified the need for additional scale‐up factors to account for non‐uniform filter area usage in large‐scale filter housings. This understanding proved critical to the final equipment design and depth filtration step definition, resulting in robust process performance at manufacturing scale. © 2005 Wiley Periodicals, Inc.
Motion retrieval based on movement notation language
Authors: Yu Tao , Shen Xiaojie , Li Qilei , Geng Weidong
Published: September 2005

With the increased availability of motion capture data, the volume of motion library grows so large that it is difficult for animators to manually browse the dataset to search desired motions for reuse. To address this issue, we implement a framework, which allows the user to retrieve motions via Labanotation. For each motion clip in the library, we generate a corresponding Labanotation sequence as additional motion property. A similarity metric for Labanotation sequences is proposed and used to search the motions that have similar Laban descriptions. Our search algorithm is able to retrieve motion segments that only match part of the query Laban sequence. Then based on dynamic programming, these segments are stitched together to form a smooth output motion that is in an optimal sense of matching query Laban sequence. Experimental results demonstrate our method could effectively improve the utilization of motion data. Copyright © 2005 John Wiley & Sons, Ltd.
Real‐time meshless deformation
Authors: Guo Xiaohu , Qin Hong
Published: September 2005

In this paper, we articulate a meshless computational paradigm for the effective modeling, accurate physical simulation, and real‐time animation of point‐sampled solid objects. Both the interior and the boundary geometry of our volumetric object representation only consist of points, further extending the powerful and popular method of point‐sampled surfaces to the volumetric setting. We build the point‐based physical model upon continuum mechanics, which affords to effectively model the dynamic elastic behavior of point‐based volumetric objects. When only surface samples are provided, our prototype system first generates both interior volumetric points and a volumetric distance field with octree structure. The physics of these volumetric points in a solid interior are simulated using the Meshless Moving Least Squares (MLS) shape functions. In sharp contrast to the traditional finite element method (FEM), the meshless property of our new technique expedites the accurate representation and precise simulation of the underlying discrete model, without the need of domain meshing. In order to achieve real‐time simulations, we utilize the warped modal analysis method that is locally linear in nature but globally warped to account for rotational deformation. The structural simplicity and real‐time performance of our meshless simulation framework are ideal for interactive animation and game/movie production. Copyright © 2005 John Wiley & Sons, Ltd.
A Multisite Molecular Mechanism for Baeyer–Villiger Oxidations on Solid Catalysts Using Environmentally Friendly H2O2 as Oxidant
Authors: Boronat Mercedes , Corma Avelino , Renz Michael , Sastre Germán , Viruela Pedro M.
Published: September 2005

The molecular mechanism of the Baeyer–Villiger oxidation of cyclohexanone with hydrogen peroxide catalyzed by the Sn‐beta zeolite has been investigated by combining molecular mechanics, quantum‐chemical calculations, spectroscopic, and kinetic techniques. A theoretical study of the location of Sn in zeolite beta was performed by using atomistic force‐field techniques to simulate the local environment of the active site. An interatomic potential for Sn/Si zeolites, which allows the simulation of zeolites containing Sn in a tetrahedral environment, has been developed by fitting it to the experimental properties of quartz and SnO2(rutile). The tin active site has been modeled by means of a Sn(OSiH3)3OH cluster, which includes a defect in the framework that provides the flexibility necessary for the interaction between the adsorbates and the Lewis acid center. Two possible reaction pathways have been considered in the computational study, one of them involving the activation of the cyclohexanone carbonyl group by Sn (1) and the other one involving hydrogen peroxide being activated through the formation of a tin–hydroperoxo intermediate (2). Both the quantum‐chemical results and the kinetic study indicate that the reaction follows mechanism 1, and that the catalyst active site consists of two centers: the Lewis acid Sn atom to which cyclohexanone has to coordinate, and the oxygen atom of the SnOH group that interacts with H2O2 forming a hydrogen bond.
Diastereoselective Hartwig–Buchwald Reaction of Chiral Amines with rac‐[2.2]Paracyclophane Derivatives
Authors: Kreis Michael , Friedmann Christian J. , Bräse Stefan
Published: September 2005

A Hartwig–Buchwald addition of a variety of chiral amines to rac‐4‐bromo‐[2.2]paracyclophane and rac‐trifluoromethanesulfonic acid (4‐[2.2]paracyclophane) ester was performed with high diastereoselectivities. Kinetic racemic resolution of the starting materials was achieved, providing a rapid access to enantiomerically enriched 4‐bromo‐[2.2]paracyclophane and the corresponding enantiomerically pure [2.2]paracyclophane amines. Additionally, the first reaction of a secondary amine with a [2.2]paracyclophane halide was achieved.
Synthesis of the Indene, THF, and Pyrrolidine Skeletons by Lewis Acid Mediated Cycloaddition of Methylenecyclopropanes with Aldehydes, N‐Tosyl Aldimines, and Acetals
Authors: Shao Li‐Xiong , Xu Bo , Huang Jin‐Wen , Shi Min
Published: September 2005

Methylenecyclopropanes (MCPs 1) react with aldehydes, N‐tosyl aldimines, and acetals to give the corresponding indene, THF, and pyrrolidine cycloaddition products in the presence of BF3⋅OEt2 under mild reaction conditions. Some special transformations of MCPs 1 with aldehydes have been reported in this paper. A plausible reaction mechanism has been discussed, which is based on a deuterium‐labeling experiment and the Prins‐type reaction mechanism.
Environmental Effects on a Prion's Helix II Domain: Copper(II) and Membrane Interactions with PrP180–193 and Its Analogues
Authors: Grasso Domenico , Grasso Giulia , Guantieri Valeria , Impellizzeri Giuseppe , La Rosa Carmelo , Milardi Danilo , Micera Giovanni , Õsz Katalin , Pappalardo Giuseppe , Rizzarelli Enrico , Sanna Daniele , Sóvágó Imre
Published: September 2005

An abnormal interaction between copper and the prion protein is believed to play a pivotal role in the pathogenesis of prion diseases. Copper binding has been mainly attributed to the N‐terminal domain of the prion protein, but this hypothesis has recently been challenged in some papers which suggest that the C‐terminal domain might also compete for metal anchoring. In particular, the segment corresponding to the helix II region of the prion protein, namely PrP180–193, has been shown both to bind copper and to exhibit a copper‐enhanced cytotoxicity, as well as to interact with artificial membranes. The present work is aimed at extending these results by choosing the most representative model of this domain and by determining its copper affinity. With this aim, the different role played by the electrostatic properties of the C‐ and N‐termini of PrP180–193 (VNITIKQHTVTTTT) in determining its conformational behaviour, copper coordination and ability to perturb model membranes was investigated. Owing to the low solubility of PrP180–193, its copper affinity was evaluated by using the shorter PrPAc184–188NH2 (IKQHT) analogue as a model. ESI‐MS, ESR, UV/Vis, and CD measurements were carried out on the copper(II)/PrPAc184–188NH2 and copper(II)/PrP180–193NH2 systems, and showed that PrPAc184–188NH2 is a reliable model for the metal interaction with the helix II domain. The affinity of copper(II) for the helix II fragment is higher than that for the octarepeat and PrP106–126 peptides. Finally, the different ability of PrP180–193 analogues to perturb the DPPC model membrane was assessed by DSC measurements. The possible biological consequences of these findings are also discussed briefly.
X‐ray Structure Determination, Absolute Configuration and Biological Activity of Phomoxanthone A
Authors: Elsässer Brigitta , Krohn Karsten , Flörke Ulrich , Root Natalia , Aust Hans‐Jürgen , Draeger Siegfried , Schulz Barbara , Antus Sándor , Kurtán Tibor
Published: September 2005

The dimeric xanthone phomoxanthone A (1a), a cytochalasin L‐696,474 (2a), the corresponding 21‐O‐deacetyl‐L‐696,474 (2b), and 3‐nitropropionic acid (3) were isolated from the endophytic fungus Phomopsis sp. The relative configuration of phomoxanthone A (1a) was elucidated by X‐ray single‐crystal analysis. The comparison of the calculated and measured CD spectra and CD calculation of model compounds revealed that the axial chirality along the biaryl axis dominates the CD spectra of the dimeric xanthone 1a, and can thus be determined by CD calculation as (aS). Knowing the axial chirality, the absolute configurations of the stereogenic centers could be determined from the X‐ray data of 1a as (5R,6R,10aR,5′R,6′R,10a′R). In addition, it was demonstrated that in both the solid state (KBr) and solution (methanol/dichloromethane, 4:1) 1a has the same conformation, i.e. similar dihedral angles along the biaryl axis. Comparison of solid‐state CD measurement with calculation of CD data based on X‐ray coordinates was introduced for the first time. Phomoxanthone A (1a) showed activity against bacteria and phytopathogenic fungi. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
An Efficient Chemoenzymatic Synthesis of the Bactericide Lapyrium Chloride
Authors: Rustoy Eduardo M. , Baldessari Alicia
Published: September 2005

An efficient route for large‐scale preparation of lapyrium chloride, a broad‐spectrum antimicrobial surfactant, was developed from chloroacetic acid in four steps, three of them enzymatic. Due to the chemoselective behavior of the biocatalysts, lapyrium chloride was obtained in a high degree of purity and yield, from mild reaction conditions and following a low environmental impact methodology. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Two‐dimensional implicit time‐dependent calculations on adaptive unstructured meshes with time evolving boundaries
Authors: Lin Paul T. , Baker Timothy J. , Martinelli Luigi , Jameson Antony
Published: September 2005

An implicit multigrid‐driven algorithm for two‐dimensional incompressible laminar viscous flows has been coupled with a solution adaptation method and a mesh movement method for boundary movement. Time‐dependent calculations are performed implicitly by regarding each time step as a steady‐state problem in pseudo‐time. The method of artificial compressibility is used to solve the flow equations. The solution mesh adaptation method performs local mesh refinement using an incremental Delaunay algorithm and mesh coarsening by means of edge collapse. Mesh movement is achieved by modeling the computational domain as an elastic solid and solving the equilibrium equations for the stress field. The solution adaptation method has been validated by comparison with experimental results and other computational results for low Reynolds number flow over a shedding circular cylinder. Preliminary validation of the mesh movement method has been demonstrated by a comparison with experimental results of an oscillating airfoil and with computational results for an oscillating cylinder. Copyright © 2005 John Wiley & Sons, Ltd.
A 3‐D non‐hydrostatic pressure model for small amplitude free surface flows
Authors: Lee J. W. , Teubner M. D. , Nixon J. B. , Gill P. M.
Published: September 2005

A three‐dimensional, non‐hydrostatic pressure, numerical model with k–ε equations for small amplitude free surface flows is presented. By decomposing the pressure into hydrostatic and non‐hydrostatic parts, the numerical model uses an integrated time step with two fractional steps. In the first fractional step the momentum equations are solved without the non‐hydrostatic pressure term, using Newton's method in conjunction with the generalized minimal residual (GMRES) method so that most terms can be solved implicitly. This method only needs the product of a Jacobian matrix and a vector rather than the Jacobian matrix itself, limiting the amount of storage and significantly decreasing the overall computational time required. In the second step the pressure–Poisson equation is solved iteratively with a preconditioned linear GMRES method. It is shown that preconditioning reduces the central processing unit (CPU) time dramatically. In order to prevent pressure oscillations which may arise in collocated grid arrangements, transformed velocities are defined at cell faces by interpolating velocities at grid nodes. After the new pressure field is obtained, the intermediate velocities, which are calculated from the previous fractional step, are updated. The newly developed model is verified against analytical solutions, published results, and experimental data, with excellent agreement. Copyright © 2005 John Wiley & Sons, Ltd.
Non‐Newtonian blood flow dynamics in a right internal carotid artery with a saccular aneurysm
Authors: Valencia Alvaro , Zarate Alvaro , Galvez Marcelo , Badilla Lautaro
Published: September 2005

Flow dynamics plays an important role in the pathogenesis and treatment of cerebral aneurysms. The temporal and spatial variations of wall shear stress in the aneurysm are hypothesized to be correlated with its growth and rupture. In addition, the assessment of the velocity field in the aneurysm dome and neck is important for the correct placement of endovascular coils. This work describes the flow dynamics in a patient‐specific model of carotid artery with a saccular aneurysm under Newtonian and non‐Newtonian fluid assumptions. The model was obtained from three‐dimensional rotational angiography image data and blood flow dynamics was studied under physiologically representative waveform of inflow. The three‐dimensional continuity and momentum equations for incompressible and unsteady laminar flow were solved with a commercial software using non‐structured fine grid with 283 115 tetrahedral elements. The intra‐aneurysmal flow shows complex vortex structure that change during one pulsatile cycle. The effect of the non‐Newtonian properties of blood on the wall shear stress was important only in the arterial regions with high velocity gradients, on the aneurysmal wall the predictions with the Newtonian and non‐Newtonian blood models were similar. Copyright © 2005 John Wiley & Sons, Ltd.
Diverse biological functions of extracellular collagen processing enzymes
Authors: Trackman Philip C.
Published: September 2005

Collagens are abundant proteins in higher organisms, and are formed by a complex biosynthetic pathway involving intracellular and extracellular post‐translational modifications. Starting from simple soluble precursors, this interesting pathway produces insoluble functional fibrillar and non‐fibrillar elements of the extracellular matrix. The present review highlights recent progress and new insights into biological regulation of extracellular procollagen processing, and some novel functions of byproducts of these extracellular enzymatic transformations. These findings underscore the notion that released propeptides and other proteolytic products of extracellular matrix proteins have important biological functions, and that structural proteins are multifunctional. An emerging concept is that a dynamic interplay exists between extracellular products and byproducts with cells that helps to maintain normal cellular phenotypes and tissue integrity. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
Nitric oxide regulates prolidase activity by serine/threonine phosphorylation
Authors: Surazynski Arkadiusz , Liu Yongmin , Miltyk Wojciech , Phang James M.
Published: September 2005

Prolidase [E.C. 3.4.13.9], a member of the matrix metalloproteinase (MMP) family, is a manganese‐dependent cytosolic exopeptidase that cleaves imidodipeptides containing C‐terminal proline or hydroxyproline. It plays an important role in collagen metabolism, matrix remodeling and cell growth. Nitric oxide (NO), a versatile signaling molecule, regulates many processes including collagen synthesis and matrix remodeling and, thereby, may modulate angiogenesis, tumor invasiveness, and metastasis. Thus, we considered that prolidase may be an important target of NO regulation. In our study, SIN I and DETA/NO were used as NO donors. Both donors increased prolidase activity in a time‐dependent and dose‐dependent manner. Prolidase activity increased not only with NO donors but also with endogenous NO in cells transfected with iNOS. The effect of iNOS was abolished by treatment with S‐methylisothiourea (SMT), a selective inhibitor of iNOS. However, with either exogenous or endogenous sources of NO, the increase in prolidase activity was not accompanied by increased prolidase expression. Therefore, we suspected phosphorylation of prolidase as a potential mechanism regulating enzyme activation. We observed increased serine/threonine phosphorylation on prolidase protein in cells treated with NO donors and in cells transfected with iNOS. To determinate the pathways that may mediate prolidase induction by NO, we first used 8‐Br‐cGMP, a cGMP agonist, and found that 8‐Br‐cGMP strongly and rapidly stimulated prolidase activity accompanied by increased phosphorylation. Rp‐8‐Br‐pCPT‐cGMP, an inhibitor of cGMP, reduced NO donor‐stimulated prolidase activity to control levels. To test wheher the MAPK pathway is involved in this NO‐dependent activation, we used an ERK1/2 inhibitor and found that it had no effect on prolidase activity increased by NO donors. These results demonstrate that NO stimulates prolidase activity by increasing serine/threonine phosphorylation through PKG‐cGMP pathway, but independent of MAPK and suggest an interaction between inflammatory signaling pathways and regulation of the terminal step of matrix degradation. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
Consideration of the mechanism of styrene/ethylene copolymerization with half‐titanocene catalysts
Authors: Yokota Kiyohiko , Kohsaka Tsuneaki , Ito Kazuhiko , Ishihara Nobuhide
Published: September 2005

Styrene/ethylene copolymerization was performed by Longo et al. with the use of a cyclopentadienyltitanium trichloride (CpTiCl3)/methylaluminoxane (MAO) system with various aluminum/titanium ratios and various monomer compositions. The obtained polymer consisted of a mixture of an ethylene–styrene pseudorandom copolymer, polyethylene, and poly(styrene‐block‐ethylene) with a syndiospecific styrene–styrene unit (SPS‐b‐PE). In this work, from the whole polymer obtained with the CpTiCl3/MAO catalyst system, the SPS‐b‐PE copolymer was separated with the temperature rising elution fractionation method, and the structure was specified by 13C NMR. The polymer obtained from the trivalent titanium catalyst, which was thought to be the active species of syndiotactic polystyrene, included both a styrene–styrene sequence and a styrene–ethylene–ethylene–styrene sequence. However, neither the styrene–ethylene–styrene sequence nor the long chain of polyethylene was included. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5041–5048, 2005
Multimodal luminescence spectra of ion‐implanted silica
Authors: Fitting H.‐J. , Salh Roushdey , Barfels T. , Schmidt B.
Published: September 2005

Thermally oxidized SiO2 layers have been implanted by oxygen and sulfur ions up to an atomic dopant fraction of about 4 at%. The cathodoluminescence spectra of these ion implanted layers show besides the characteristic bands an identical sharp and intensive multimodal structure in the green up to near IR region. The energy step differences of the luminescence sublevels in average amount to 120 meV and indicate vibronic transitions in terms of a configuration coordinate potential model. A most probable candidate for these spectra are O2– interstitial molecules, as we could demonstrate by respective configuration coordinate data. These assumptions are contrary to photonic crystal models for the multimodal spectra as well as to models of quantum size effects, both discussed recently in literature. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electronic structure of the active site with two configurations of azurin
Authors: Sugiyama Ayumu , Sugimori Kimikazu , Shuku Tomofumi , Nakamura Taichi , Saito Hiroaki , Nagao Hidemi , Kawabe Hiroyuki , Nishikawa Kiyoshi
Published: September 2005

We present two cluster models of the active site of azurin. These models are determined by two stable configurations during our molecular dynamics (MD) simulation. In MD simulation, we find two stable configurations connected by the “jump motion” of Met121. One configuration is similar to the crystal structure by X‐ray analysis, and the other is not the same. We perform density functional calculations for these two models and investigate physical properties such as total energy, singly occupied molecular orbital (SOMO), and spin density for each model. We find the difference in the shape of SOMO each other. We also estimate the reduction potential for each model and discuss the reduction potential and solvent effect of each model in relation to the electron transfer, which is one of the functionality of azurin. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Application invariants: Design by Contract augmented with deployment correctness logic
Authors: Savidis Anthony
Published: September 2005

Design by Contract is a method for the development of robust object‐oriented software, introducing class invariants as conditions corresponding to the design axioms that should be satisfied by every valid instance of a class. Additionally, the method states formally the way client programs should correctly utilize supplier classes, so that the composition of correct programs may be accomplished. However, the contextual correctness of supplier instances within client programs, only reflected in the client‐specific semantics for supplier‐class deployment, cannot be expressed through Design by Contract. For instance, supplier instances satisfying the supplier class invariant may not constitute plausible supplier instances in the context of a particular client program. In this context, we introduce application invariants as an extension to Design by Contract, for hosting the contextual‐correctness logic for supplier instances, as conditionally defined by client programs. This allows stronger validation of supplier instances, through the dynamic encapsulation of client‐specific acceptance filtering, enabling more intensive defect detection. Application invariants are implemented in the context of client classes as methods utilizing correctness condition expressions, are dynamically hosted within supplier instances, while always called by supplier instances when the basic supplier‐class invariant test is performed. Copyright © 2005 John Wiley & Sons, Ltd.
A giant unilateral pulmonary artery aneurysm: Case report
Authors: Gökhan Cin Veli , Özer Faruk , Deveci Ahmet , Yaşar Savaş
Published: September 2005

A 65-year-old man presented with a left-sided pulmonary artery aneurysm with a fusiform shape. He was considered to be inoperable. Pulmonary hypertension is common with right heart enlargement, as in the present case. Posttraumatic aneurysms have also been reported. Differential diagnosis must distinguish between these two conditions. If 2D echo and CT have failed to distinguish the condition then right heart catheterization and pulmonary angiography are the methods of choice.
DETERMINANT EXPRESSIONS FOR HYPERELLIPTIC FUNCTIONS
Authors: ÔNISHI YOSHIHIRO
Published: September 2005

In this paper we give an elegant generalization of the formula of Frobenius–Stickelberger from elliptic curve theory to all hyperelliptic curves. A formula of Kiepert type is also obtained by a limiting process from this generalization. In the appendix a determinant expression of D. G. Cantor is also derived.
ANALYSIS OF AN EIGENVALUE PROBLEM ARISING IN A THERMAL WAVE PROPAGATION PROBLEM
Authors: Needham D. J. , King A. C.
Published: September 2005

In this paper we study a non-standard eigenvalue problem which arises in the context of a thermal wave propagation problem, and some generalizations thereof. The eigenvalue distribution is fully explored and useful bounds on the location of the eigenvalues are obtained.
A simulation study on detecting purging of inbreeding depression in captive populations
Authors: BOAKES ELIZABETH , WANG JINLIANG
Published: September 2005

Inbreeding depression threatens the survival of small populations of both captive and wild outbreeding species. In order to fully understand this threat, it is necessary to investigate what role purging plays in reducing inbreeding depression. Ballou (1997) undertook such an investigation on 25 mammalian populations, using an ancestral inbreeding regression model to detect purging. He concluded that there was a small but highly significant trend of purging on neonatal survival across the populations. We tested the performance of the regression model that Ballou used to detect purging on independently simulated data. We found that the model has low statistical power when inbreeding depression is caused by the build-up of mildly deleterious alleles. It is therefore possible that Ballou's study may have underestimated the effects of ancestral inbreeding on the purging of inbreeding depression in captive populations if their inbreeding depression was caused mainly by mildly deleterious mutations. We also developed an alternative regression model to Ballou's, which showed an improvement in the detection of purging of mildly deleterious alleles but performed less well if deleterious alleles were of a large effect.
Immunochemical quantification of heat denaturation of camel (Camelus dromedarius) whey proteins
Authors: Levieux Didier , Levieux Annie , El-Hatmi Halima , Rigaudière Jean-Paul
Published: September 2005

The major whey proteins IgG, serum albumin and α-lactalbumin were purified from camel milk using gel permeation and ion-exchange chromatography. Specific antisera against each of them were raised and used to quantify their heat denaturation in early or mature milk over a range of 60–90 °C for 10–60 min using the single radial immunodiffusion technique. The heat denaturation midpoints for the mature milk heated 30 min were 67·2, 73·0 and 77·5 °C for IgG, albumin and α-lactalbumin respectively. The early milk was more sensitive to heat treatment with coagulation at low temperature and heat denaturation midpoints of 64·8, 71·6 and 72·6 °C respectively. This difference was related to the high IgG content of the early milk (12·6 mg/ml v. 0·5 mg/ml for the mature milk) and stresses the importance of monitoring the IgG level of milk to assess the absence of colostrum.
Operational cost minimization of heat pump for milk pasteurization in dairy
Authors: Söylemez Mehmet Sait
Published: September 2005

A thermo economic optimization analysis is presented yielding simple algebraic formula for estimating the optimum operating conditions of interconnected heat pump assisted milk pasteurizing systems. The overall operational cost method including the cost of auxiliary heater is used in the present study, together with the thermal analyses of all system components, for thermo economic analysis of the system.
The prevalence ofNeospora caninumand co-infection withToxoplasma gondiiby PCR analysis in naturally occurring mammal populations
Authors: HUGHES J. M. , WILLIAMS R. H. , MORLEY E. K. , COOK D. A. N. , TERRY R. S. , MURPHY R. G. , SMITH J. E. , HIDE G.
Published: September 2005

Neospora caninumandToxoplasma gondiiare closely related intracellular protozoan parasites associated with bovine and ovine abortion respectively. Little is known about the extent ofNeospora/Toxoplasmaco-infection in naturally infected populations of animals. Using nested PCR techniques, based on primers from the Nc5 region ofN. caninumand SAG1 forT. gondii, the prevalence ofN. caninumand its co-infection withT. gondiiwere investigated in populations ofMus domesticus,Rattus norvegicusand aborted lambs (Ovis aries). A low frequency of infection withN. caninumwas detected in theMus domesticus(3%) andRattus norvegicus(4·4%) populations. A relatively high frequency of infection withN. caninumwas detected in the brains of aborted lambs (18·9%). There was no significant relationship betweenN. caninumandT. gondiico-infection. Investigation of the tissue distribution ofNeospora, in aborted lambs, showed thatNeosporacould not be detected in tissues other than brain and this was in contrast toToxoplasmawhere the parasite could be frequently detected in a range of tissues.
Brain anatomy in non-affected parents of autistic probands: a MRI study
Authors: PALMEN SASKIA J. M. C. , HULSHOFF POL HILLEKE E. , KEMNER CHANTAL , SCHNACK HUGO G. , SITSKOORN MARGRIET M. , APPELS MELANIE C. M. , KAHN RENÉ S. , VAN ENGELAND HERMAN
Published: September 2005

Background. Autism is a neurodevelopmental disorder with an estimated genetic origin of 90%. Previous studies have reported an increase in brain volume of approximately 5% in autistic subjects, especially in children. If this increase in brain volume is genetically determined, biological parents of autistic probands might be expected to show brain enlargement, or at least intracranial enlargement, as well. Identifying structural brain abnormalities under genetic control is of particular importance as these could represent endophenotypes of autism.

Method. Using quantitative anatomic brain magnetic resonance imaging, volumes of intracranial, total brain, frontal, parietal, temporal and occipital lobe, cerebral and cortical gray and white matter, cerebellum, lateral ventricle, and third ventricle were measured in biological, non-affected parents of autistic probands (19 couples) and in healthy, closely matched control subjects (20 couples).

Results. No significant differences were found between the parents of the autistic probands and healthy control couples in any of the brain volumes. Adding gender as a factor in a second analysis did not reveal a significant interaction effect of gender by group.

Conclusions. The present sample of biological, non-affected parents of autistic probands did not show brain enlargements. As the intracranium is not enlarged, it is unlikely that the brain volumes of the parents of autistic probands have originally been enlarged and have been normalized. Thus, increased brain volume in autism might be caused by the interaction of paternal and maternal genes, possibly with an additional effect of environmental factors, or increased brain volumes might reflect phenotypes of autism.
Agriculture expansion and deforestation in seasonally dry forests of north-west Argentina
Authors: GRAU H. RICARDO , GASPARRI N. IGNACIO , AIDE T. MITCHELL
Published: September 2005

In Argentina, deforestation due to agriculture expansion is threatening the Semi-arid Chaco, one of the largest forested biomes of South America. This study focuses on the north-west boundary of the Argentine Semi-arid Chaco, where soybean is the most important crop. Deforestation was estimated for areas with different levels of soil and rainfall limitation for agriculture between 1972 and 2001, with a finer analysis in three periods starting in 1984, which are characterized by differences in rainfall, soybean price, production cost, technology-driven yield and national gross domestic product. Between 1972 and 2001, 588 900 ha (c. 20% of the forests) were deforested. Deforestation has been accelerating, reaching >28 000 ha yr−1 after 1997. The initial deforestation was associated with black bean cultivation following an increase in rainfall during the 1970s. In the 1980s, high soybean prices stimulated further deforestation. Finally, the introduction of soybean transgenic cultivars in 1997 reduced plantation costs and stimulated a further increase in deforestation. The domestic economy had little association with deforestation. Although deforestation was more intense in the moister (rainfall >600 mm yr−1) areas, more than 300 000 ha have already been deforested in the drier areas, suggesting that climatic limitations are being overcome by technological and genetic improvement. Furthermore, more than 300 000 ha of forest occur in sectors without major soil and rainfall limitations. If global trends of technology, soybean markets and climate continue, and no active conservation policies are applied, vast areas of the Chaco will be deforested in the coming decades.
A microcosm system for the study of cryptoendolithic microbial biofilms from desert ecosystems
Authors: Kurtz H. D. , Cox R. , Reisch C.
Published: September 2005

Study of natural microbial ecosystems is hampered by our inability to closely duplicate the development of a community in the laboratory environment. The lack of such systems is particularly acute when endolithic microbes are examined. In this study, we have developed a system that enables laboratory growth of cryptoendolithic microbial communities resembling those found in the porous sandstones making up the Colorado Plateau in southeastern Utah. Microscopic examination of natural and in vitro cryptoendolithic biofilms shows that, on a gross level, the laboratory biofilm is developing in a fashion that is structurally similar to that of the native community. Further confirmation that the laboratory system resembles the native community was obtained by using denaturing gradient gel electrophoresis (DGGE) and DNA sequence analysis to examine the biofilms for the presence of cyanobacteria and the Geobacteriaceae. We found that the molecular profiles for these two groups of bacteria were nearly identical in the native and in vitro biofilms. These data show that our system for growing cryptoendolithic bacteria in the laboratory is suitable for the study of these ecosystems and will allow for experimental manipulations that are not possible in the field.
A seasonal intrusion of subtropical water in the Mozambique Channel
Authors: Schouten Mathijs W. , de Ruijter Wilhelmus P. M. , Ridderinkhof Herman
Published: September 2005

An episode of subtropical water intruding in the tropical waters north of Madagascar during the austral summer of 2001 is documented by a combination of satellite derived surface chlorophyll and sea surface height observations and simultaneous in‐situ observations of velocity, chemical and biological tracers. A westward jet clearly of subtropical origin is found in the Comoros basin as a continuation of the South Equatorial Current. Further west, a strong anticyclonic Mozambique eddy is formed north of the narrows, that propagates southward into the Channel. The phenomenon documented here seems to occur each austral summer, and may be part of the adjustment to the seasonal variations in the wind forcing over the subtropical and tropical gyres.
Spatiotemporal Distribution of Spectrin Breakdown Products Induced by Anoxia in Adult Rat Optic Nerve in Vitro
Authors: Jette Nathalie , Coderre Elaine , Nikolaeva Maria A , Enright Paula D , Iwata Akira , Smith Douglas H , Jiang Qiubo , Stys Peter K
Published: September 2005

Hypoxic/ischemic and traumatic injury to central nervous system myelinated axons is heavily dependent on accumulation of Ca ions in the axoplasm, itself promoted by Na influx from the extracellular space. Given the high density of nodal Na channels, we hypothesized that nodes of Ranvier might be particularly vulnerable to Ca overload and subsequent damage, as this is the expected locus of maximal Na influx. Adult rat optic nerves were exposed to in vitro anoxia and analyzed immunohistochemically for the presence of spectrin breakdown. Cleavage of spectrin became detectable between 15 and 30 mins of anoxia, and increased homogeneously along the lengths of fibers; localized breakdown was not observed at nodes of Ranvier at any time point analyzed. Spectrin breakdown was also found in glial processes surrounding axons. Confocal imaging of axoplasmic Ca also revealed a gradual and nonlocalized increase as anoxia progressed, without evidence of Ca ‘hot-spots’ anywhere along the axons at any time between 0 and 30 mins of anoxic exposure in vitro. Calculations of Ca diffusion rates indicated that even if Ca entered or was released focally in axons, this ion would diffuse rapidly into the internodes and likely produce diffuse injury by activating Ca-dependent proteases. Western blot analysis for voltage-gated Na channel protein revealed that key functional proteins such as these are also degraded by anoxia/ischemia. Thus, proteolysis of structural and functional proteins will conspire to irreversibly injure central axons and render them nonfunctional, eventually leading to transection, degradation, and Wallerian degeneration.
Deconvolution of the relaxations associated with local and segmental motions in poly(methacrylate)s containing dichlorinated benzyl moieties in the ester residue
Authors: Dominguez-Espinosa Gustavo , Díaz-Calleja Ricardo , Riande Evaristo , Gargallo Ligia , Radic Deodato
Published: September 2005

The relaxation behavior of poly(2,3-dichlorobenzyl methacrylate) is studied by broadband dielectric spectroscopy in the frequency range of 10−1–109Hz and temperature interval of 303–423K. The isotherms representing the dielectric loss of the glassy polymer in the frequency domain present a single absorption, called β process. At temperatures close to Tg, the dynamical α relaxation already overlaps with the β process, the degree of overlapping increasing with temperature. The deconvolution of the α and β relaxations is facilitated using the retardation spectra calculated from the isotherms utilizing linear programming regularization parameter techniques. The temperature dependence of the β relaxation presents a crossover associated with a change in activation energy of the local processes. The distance between the α and β peaks, expressed as log(fmax;β∕fmax;α) where fmax is the frequency at the peak maximum, follows Arrhenius behavior in the temperature range of 310–384K. Above 384K, the distance between the peaks remains nearly constant and, as a result, the α onset temperature exhibited for many polymers is not reached in this system. The fraction of relaxation carried out through the α process, without β assistance, is larger than 60% in the temperature range of 310–384K where the so-called Williams ansatz holds.
Thermopower enhancement in PbTe with Pb precipitates
Authors: Heremans Joseph P. , Thrush Christopher M. , Morelli Donald T.
Published: September 2005

The thermoelectric power of polycrystalline PbTe samples containing nanometer-sized precipitates of Pb metal is enhanced over that of bulk PbTe. Samples of PbTe containing excess Pb and Ag were prepared using conventional metallurgical heat treatments. These samples are shown, by x-ray diffraction, by microscopy, and by the presence of a superconductive transition, to contain Pb precipitates with sizes on the order of 30–40nm. The thermopower enhancement is related to an increase in the energy dependence of the relaxation time, as evidenced by a complete set of measurements of thermoelectric and thermomagnetic transport coefficients.
Effective parameters of resonant negative refractive index metamaterials: Interpretation and validity
Authors: Seetharamdoo Divitha , Sauleau Ronan , Mahdjoubi Kouroch , Tarot Anne-Claude
Published: September 2005

We present a numerical study of resonant negative refractive index (NRI) metamaterials in which their effective parameters are calculated. For a periodic media consisting of split-ring resonators and metallic wires the effective refractive index is compared by means of two different methods. The first one is an inversion procedure in which the effective refractive index is calculated from the reflection and transmission coefficients of a finite structure and the second one consists its calculation from the phase velocity issued from the dispersion diagram. A significant difference between the two cases is highlighted in the frequency interval of interest (NRI regime) and for the finite media, counterintuitive observations are made. These anomalous features are observed in a frequency range in which there is a non-negligible contribution of the higher-order modes to propagation inside the periodic metamaterial. Hence in this particular frequency interval, the media cannot be described by an effective refractive index in a Fresnel sense. In other frequency regions, both methods converge and it will be shown that the metamaterial exhibits a negative refractive index.
Charge trapping and detrapping characteristics in hafnium silicate gate dielectric using an inversion pulse measurement technique
Authors: Choi Rino , Song S. C. , Young C. D. , Bersuker Gennadi , Lee Byoung Hun
Published: September 2005

Threshold voltage (VTH) instability in metal oxide semiconductor field transistors (MOSFETs) with high dielectric constant (k) gate dielectrics has been investigated with an inversion pulse measurement technique, which can detect fast dielectric charging/discharging within microseconds (μs). The results indicate that VTH instability can be significantly underestimated by conventional VTH measurement techniques. Based on temperature-dependent stress data, it is suggested that charging and discharging are determined by direct tunneling and thermally assisted processes, respectively.
High mobility n-channel organic thin-film transistors and complementary inverters
Authors: Gundlach D. J. , Pernstich K. P. , Wilckens G. , Grüter M. , Haas S. , Batlogg B.
Published: September 2005

We report on n-channel organic thin-film transistors (OTFTs) with field-effect mobility comparable to that typically reported for p-channel OTFTs fabricated from pentacene. The OTFTs were fabricated on oxidized silicon wafers using N,N′-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (PTCDI–C13H27) as the semiconductor and with Au, Cr, Al, and LiF∕Al source and drain contacts. Accumulation mode n-channel transistor operation is demonstrated for all contact metals despite the large differences in their work functions. High field-effect mobility near 0.6cm2∕Vs and large Ion∕Ioff of 107 were achieved. Device performance is sufficient to demonstrate pentacene∕PTCDI–C13H27 TFT complementary inverters with record gain.
Atomic-scale manipulation of potential barriers at SrTiO3 grain boundaries
Authors: Prabhumirashi Pradyumna , Dravid Vinayak P. , Lupini Andrew R. , Chisholm Matthew F. , Pennycook Stephen J.
Published: September 2005

In oxide grain boundaries (GBs), oxygen ions and their vacancies serve as a common denominator in controlling properties such as GB barrier height and capacitance. Therefore, it is critical to analyze, control and manipulate oxygen and vacancies at oxide interfaces as most of the practical devices are almost always influenced by the presence of electrostatic potential barriers at interfaces. Here, we report adjustment of a single GB potential barrier via manipulation of oxygen vacancy concentration using simple oxidation and reduction treatments. We validate our analysis with aberration-corrected HAADF imaging and column-by-column EELS coupled with macroscopic transport measurements of isolated GBs to gain important insight into the physical attributes of GB potential barriers.
Fabrication of high-density arrays of individually isolated nanocapacitors using anodic aluminum oxide templates and carbon nanotubes
Authors: Sohn Jung Inn , Kim Youn-Su , Nam Chunghee , Cho B. K. , Seong Tae-Yeon , Lee Seonghoon
Published: September 2005

We have fabricated high-density arrays of individually isolated semispherical nanocapacitors consisting of porous anodic aluminum oxide (AAO) layers as dielectric materials and carbon nanotubes (CNTs) as electrodes. It is shown that the nanocapacitors made with the CNT electrodes exhibit much better C-V behaviors than those without the CNT electrodes. The improved electrical behavior is explained in terms of the use of the CNT electrodes deposited within the porous AAO layers. The capacitance calculated using semispherical capacitor formula is in agreement with the experimental value.
Impact of metal silicide precipitate dissolution during rapid thermal processing of multicrystalline silicon solar cells
Authors: Buonassisi T. , Istratov A. A. , Peters S. , Ballif C. , Isenberg J. , Riepe S. , Warta W. , Schindler R. , Willeke G. , Cai Z. , Lai B. , Weber E. R.
Published: September 2005

Synchrotron-based analytical x-ray microprobe techniques were employed to study the dissolution of iron, copper, and nickel silicide precipitates at structural defects in cast multicrystalline silicon in response to rapid thermal processing (RTP). A direct correlation was observed between iron silicide precipitate dissolution, increased minority carrier recombination, and decreased device performance after high-temperature (1000°C) RTP. In contrast, iron precipitates comparable in size to as-grown material remained after lower-temperature RTP (860°C); in this case the material exhibited higher minority carrier diffusion length and better solar cell performance. RTP at both temperatures effectively dissolved nickel and copper silicide precipitates. It is concluded that iron dissolved from structural defect reservoirs detrimentally affects the cell performance, likely by forming distributed point defects and smaller precipitates. For cast multicrystalline silicon, higher performance can be expected by inhibiting the dissolution of these precipitates, i.e., by reducing the time and/or temperature of processing steps.