bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photochemistry and Photobiology of Cryptochrome Blue‐light Photopigments: The Search for a Photocycle
Authors: Partch Carrie L. , Sancar Aziz 
Published: September 2005

ABSTRACTCryptochromes are flavoproteins that exhibit high sequence and structural similarity to the light‐dependent DNA‐repair enzyme, photolyase. Cryptochromes have lost the ability to repair DNA; instead, they use the energy from near‐UV/blue light to regulate a variety of growth and adaptive processes in organisms ranging from bacteria to humans. The photocycle of cryptochrome is not yet known, although it is hypothesized that it may share some similarity to that of photolyase, which utilizes light‐driven electron transfer from the catalytic flavin chromophore. In this review, we present genetic evidence for the photoreceptive role of cryptochromes and discuss recent biochemical studies that have furthered our understanding of the cryptochrome photocycle. In particular, the role of the unique C‐terminal domain in cryptochrome phototransduction is discussed.
Copolymerization of N‐(4‐carboxyphenyl) itaconimide or N‐(4‐carboxyphenyl) itaconamic acid with methyl methacrylate
Authors: Chauhan Rashmi , Choudhary Veena 
Published: September 2005

AbstractThis paper describes the synthesis and characterization of N‐(4‐carboxyphenyl) itaconamic acid (CPA) and N‐(4‐carboxyphenyl) itaconimide (CPI) obtained by reacting itaconic anhydride with p‐aminobenzoic acid. Structural and thermal characterization of CPA and CPI was done using 1H‐NMR, FTIR, and differential scanning calorimetry (DSC). Copolymerization of CPA or CPI with methyl methacrylate (MMA) in solution was carried out at 60 °C using azobisisobutyronitrile as an initiator and dimethyl acetamide or THF as solvent. Feed compositions having varying mole fractions of CPA or CPI ranging from 0.05–0.20 or 0.1–0.5 were taken to prepare copolymers. Copolymerizations were terminated at low percentage conversion. Structural characterization of copolymers was done by 1H‐NMR and elemental analysis. Copolymer composition was determined using percentage nitrogen content. The reactivity ratios were r1 (MMA) = 0.68 ± 0.06 and r2 (CPI) = 0.46 ± 0.06. The intrinsic viscosity [η] was determined using an Ubbelohde suspension level viscometer. [η] decreased with increasing mole fraction of N‐(p‐carboxyphenyl) itaconimide or N‐(p‐carboxyphenyl) itaconamic acid in copolymers. Glass transition temperature and thermal stability of the copolymers were determined using DSC and thermogravimetric analysis, respectively. The glass transition temperature (Tg) as determined from DSC scans increased with increasing amounts of CPA or CPI in copolymers. A significant improvement in the char yield was observed upon copolymerization. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1909–1915, 2005
Studies on miscibility of blends of poly (ethylene acrylic acid) and ethylene‐co‐vinyl acetate by melt rheology
Authors: Siddaramaiah  , Bhattacharya A. K. , Nando G. B. 
Published: September 2005

AbstractRheological behavior of blends of poly (ethylene‐acrylic acid) (EAA) and ethylene vinyl acetate (EVA) copolymer have been carried out at various temperatures, namely, 100, 110, and 120°C, and different shear rates from 61.33 to 613.30 s−1 using a Monsanto Processability Tester. The melt viscosity of the blends shows synergism during processing. The activation energy of the blends is in the range 20.7–44.6 kJ/mol. Highest activation energy was observed for the blends containing 40–60% of EVA by weight. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1947–1954, 2005
Oligopeptides as catalysts for asymmetric epoxidation
Authors: Kelly David R. , Roberts Stanley M. 
Published: September 2005

AbstractOligopeptides 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, 2006This 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

AbstractRobust 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

AbstractWith 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

AbstractIn 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

AbstractThe 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

AbstractA 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

AbstractMethylenecyclopropanes (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

AbstractAn 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

AbstractThe 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

AbstractAn 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

AbstractAn 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

AbstractA 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

AbstractFlow 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

AbstractCollagens 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

AbstractProlidase [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.