bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mixed‐Valence Cobalt(II/III) Carboxylate Clusters: CoII4CoIII2 and CoIICoIII2 Complexes from the Use of 2‐(Hydroxymethyl)pyridine
Authors: Stamatatos Theocharis C. , Boudalis Athanassios K. , Pringouri Konstantina V. , Raptopoulou Catherine P. , Terzis Aris , Wolowska Joanna , McInnes Eric J. L. , Perlepes Spyros P. 
Published: September 2007

AbstractAerobic reactions of Co(O2CR)2 with 2‐(hydroxymethyl)pyridine (hmpH), in the presence of ClO4– counterions give the hexanuclear, mixed‐valence clusters [CoII4CoIII2(O2CR)4(hmp)8](ClO4)2 [R = Me (1), Ph (2)] which possess the unprecedented [CoII4CoIII2(μ3‐OR′)4(μ‐OR′)4]6+ [R′ = (2‐pyridyl)CH2‐] core. Replacement of ClO4– by N3– in the reaction mixture that gives 1 leads to the linear complex [CoIII,II,III3(O2CMe)2(N3)2(hmp)4] (3). Q‐band EPR spectra and variable‐temperature magnetic susceptibility studies for 1 and 2 provide strong evidence that the CoII ions are antiferromagnetically coupled.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Uniformly Nucleobase‐Functionalized β‐Peptide Helices: Watson–Crick Pairing or Nonspecific Aggregation
Authors: Weiß Angelina , Diederichsen Ulf 
Published: September 2007

AbstractThe organization and architecture of helices is fundamental in folding of protein tertiary structures. Therefore, stable β‐peptide helices are used as models for the selective organization of secondary structures. Nucleobases are already established as recognition elements to organize two β‐peptide helices in antiparallel orientation. The investigation of β‐peptide helices uniformly functionalized with one type of nucleobases provided further insight in the recognition mode and requirements for specific interaction within the linear and very rigid helical backbone topology. Specific helix interaction based on base pair recognition is predominant as soon as Watson–Crick pairing is allowed. If the hydrogen bonding donor/acceptor pattern prohibits the Watson–Crick geometry, a quite stable nonspecific interaction was found based on aromatic interactions or on a nonspecific hydrogen bonding network. The latter aggregation was also confirmed with tyrosine side chains.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Preparation of Chiral Homoannularly Bridged N,P‐Ferrocenyl Ligands by Intramolecular Coupling of 1,5‐Dilithioferrocenes and Their Application in Asymmetric Allylic Substitution Reactions
Authors: Fukuzawa Shin‐ichi , Yamamoto Masahisa , Hosaka Mitsuteru , Kikuchi Satoshi 
Published: September 2007

AbstractHomoannularly bridged ferrocene 6b was prepared by intramolecular coupling of 1,5‐dilithioferrocene 5b mediated by Fe(acac)3. Dilithioferrocene 5b was prepared by lithium–halogen exchange of the corresponding diiodide, which was prepared by 1,5‐dilithiation of the o‐TMS‐blocked ferrocene and followed by trapping with iodine and removal of the TMS group. Alternatively, 5b could be readily prepared by the reaction of o‐bromophenylferrocene 8 with nBuLi (>2 equiv.). The benzene ring of 6b underwent ortho lithiation with tBuLi, and the resulting lithiated species was trapped with Ph2PCl to produce corresponding aminophosphane 7d. Aminophosphane 13, which has the phosphanyl group on the cyclopentadienyl ring, was prepared by intramolecular coupling of 1,5‐dilithiated PhPPFA 11 mediated by Fe(acac)3. New N,P ligands 7d and 13 were used in the palladium‐catalyzed allylic alkylation and amination of 1,3‐diphenyl‐2‐propenyl acetate (14), and ligand 7d was found to give good yields with enantioselectivities as high as 96 % ee. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Experimental investigation on a base isolation system incorporating steel–Teflon sliders and pressurized fluid viscous spring dampers
Authors: Sorace Stefano , Terenzi Gloria , Magonette Georges , Molina Francisco J. 
Published: September 2007

AbstractAn experimental investigation on a base isolation system incorporating stainless steel–Teflon bearings as sliders, and pressurized fluid viscous spring dampers, is presented in this paper. In the system examined, dampers are connected to the base floor of an isolated building to provide the desired passive control of response in the superstructure, as well as to guarantee that it re‐centres completely after the termination of a seismic action. Two types of experiments were conducted: sinusoidal and random cyclic tests, and a pseudodynamic test in ‘substructured’ configuration. The cyclic tests were aimed at characterizing what follows: the hysteretic and strain‐rate‐dependent response of the considered highly non‐linear spring dampers; the normal pressure‐ and strain‐rate‐dependent frictional behaviour of steel–Teflon bearings, manufactured in compliance with the latest standards for this class of sliders; and the combined response of their assembly. The pseudodynamic test simulated the installation of the protection system at the base of a 2:3‐scale three‐storey steel frame structure, already tested in unprotected conditions by an earlier experimental campaign. Among other findings, the results of the performed tests, as well as of relevant mechanical interpretation and numerical simulation analyses, confirmed the linear additive combination of the dissipative actions of spring dampers and sliders in this mixed installation, and the high protective performance of the considered base isolation/supplemental damping system in a realistic earthquake simulation. Copyright © 2007 John Wiley & Sons, Ltd.
The impact of depression removal on catchment geomorphology, soil erosion and landscape evolution
Authors: Hancock G. R. 
Published: September 2007

AbstractThe current generation of landscape evolution models use a digital elevation model for landscape representation. These programs also contain a hydrological model that defines overland flow with the drainage network routed to an outlet. One of the issues with landscape evolution modelling is the hydrological correctness of the digital elevation model used for the simulations. Despite the wide use and increased quality of digital elevation models, data pits and depressions in the elevation data are a common feature and their removal will remain a necessary step for many data sets. This study examines whether a digital elevation model can be hydrologically correct (i.e. all depressions removed so that all water can run downslope) before use in a landscape evolution model and what effect depression removal has on long‐term geomorphology and hydrology. The impact on sediment transport rates is also examined. The study was conducted using a field catchment and a proposed landform for a post‐mining landscape. The results show that there is little difference in catchment geomorphology and hydrology for the non‐depression removed and depression removed data sets. The non‐depression removed and depression removed digital elevation models were also evaluated as input to a landscape evolution model for a 50 000 year simulation period. The results show that after 1000 years there is little difference between the data sets, although sediment transport rates did vary considerably early on in the simulation. Copyright © 2007 John Wiley & Sons, Ltd.
Wireless signal‐preamble assisted Mach–Zehnder modulator bias stabilisation in wireless signal transmission over optical fibre
Authors: Chanda Debashis , Sesay Abu 
Published: September 2007

AbstractLithium niobate based Mach–Zehnder electro‐optic modulators are increasingly being used in high‐speed digital as well as analog optical links. Depending on the application, digital or analog, the bias point of such a modulator is held constant at a particular point on the sinusoidal electrical to optical power transfer characteristics of the modulator. Bias point drift is one of the major limitations of lithium niobate based Mach–Zehnder electro‐optic modulators. This increases the bit error rate of the system and affects adjacent channel performances. In one of the most popular methods of bias control, a pilot tone is used to track the bias point drift. However, pilot tone based bias tracking reduces overall intermodulation free dynamic range of the link. In this paper we propose a method where Mach–Zehnder modulator bias drift is tracked and maintained at the desired point by tracking the power variation of the preamble of wireless signal data frames. The method has no detrimental effects on system performances as no external signal is exclusively injected into the system for bias tracking purposes. Copyright © 2007 John Wiley & Sons, Ltd.
Vasculogenesis, angiogenesis, and arteriogenesis: Mechanisms of blood vessel formation and remodeling
Authors: Semenza Gregg L. 
Published: September 2007

AbstractIn this review, the concept of oxygen homeostasis will be presented as an organizing principle for discussion of the phylogeny, ontogeny, physiology, and pathology of blood vessel formation and remodeling, with a focus on molecular mechanisms and potential therapeutic applications. J. Cell. Biochem. 102: 840–847, 2007. © 2007 Wiley‐Liss, Inc.
Specific LPA receptor subtype mediation of LPA‐induced hypertrophy of cardiac myocytes and involvement of Akt and NFκB signal pathways
Authors: Chen Jinghai , Chen Yuefeng , Zhu Weiquan , Han Yu , Han Bianmei , Xu Ruixia , Deng Linzi , Cai Yan , Cong Xiangfeng , Yang Yuejing , Hu Shengshou , Chen Xi 
Published: September 2007

AbstractLysophosphatidic acid (LPA) is a bioactive phospholipid with diverse functions mediated via G‐protein‐coupled receptors (GPCRs). In view of the elevated levels of LPA in acute myocardial infarction (MI) patients we have conducted studies aimed at identifying specific LPA receptor subtypes and signaling events that may mediate its actions in hypertrophic remodeling. Experiments were carried out in cultured neonatal rat cardiomyocytes (NRCMs) exposed to LPA and in a rat MI model. In NRCMs, LPA‐induced hypertrophic growth was completely abrogated by DGPP, an LPA1/LPA3 antagonist. The LPA3 agonist OMPT, but not the LPA2 agonist dodecylphosphate, promoted hypertrophy as examined by3[H]‐Leucine incorporation, ANF‐luciferase expression and cell area. In in vivo experiments, LPA1, LPA2 and LPA3 mRNA levels as well as LPA1 and LPA3 protein levels increased together with left ventricular remodeling (LVRM) after MI. In addition, LPA stimulated the phosphorylation of Akt and p65 protein and activated NF‐κB‐luciferase expression. Inhibitors of PI3K (wortmannin), mTOR (rapamycin), and NF‐κB (PDTC or SN50) effectively prevented LPA‐induced3[H]‐Leucine incorporation and ANF‐luciferase expression. Furthermore, ERK inhibitors (U0126 and PD98059) suppressed LPA‐stimulated activation of NF‐κB and p65 phosphorylation whereas wortmannin showed no effect on NF‐κB activation. Our findings indicate that LPA3 and/or LPA1 mediate LPA‐induced hypertrophy of NRCMs and that LPA1 and LPA3 may be involved in LVRM of MI rats. Moreover, Akt and NF‐κB signaling pathways independently implicate in LPA‐stimulated myocardial hypertrophic growth. J. Cell. Biochem. 103: 1718–1731, 2008. © 2007 Wiley‐Liss, Inc.
Adhesive biomaterials for tissue reconstruction
Authors: Lauto Antonio , Mawad Damia , Foster L. John R. 
Published: September 2007

AbstractTissue reconstruction and wound closure rely on sutures, staples and clips in current surgical procedures. These traditional devices are nonetheless unable to prevent leakage of fluids from a variety of tissue including blood vessels and dura mater. Furthermore, sutures are usually difficult to apply during minimal invasive surgery and often induce detrimental scarring that may impair healing. To overcome these disadvantages, biocompatible and biodegradable glues based on fibrin, polyethylene glycol (PEG) and cyanoacrylate have recently been used in patients to seal and repair tissue wounds. Cyanoacrylate glues create typically very strong tissue bonds but have mostly been applied externally for skin wound closure because of their residual cytotoxicity. Other adhesive biomaterials are also emerging; these glues and adhesives are usually based on proteins such as albumin and collagen or polysaccharides like chitosan; these are irradiated with coherent or non‐coherent light to trigger their adhesion to tissue. These biomaterial based devices offer significant advantages over sutures, such as their sealing or repairing ability, easy application modality and delivery in situ of compounds for accelerating wound healing. This paper reviews different tissue reconstruction strategies employing adhesive biomaterials currently used in surgical and experimental procedures. Copyright © 2007 Society of Chemical Industry
Adlayer structure of octa‐alkoxy‐substituted copper(II) phthalocyanine on Au(111) by electrochemical scanning tunneling microscopy
Authors: Wang Li , Ou‐Yang Liangyue , Yau Shueh‐Lin 
Published: September 2007

AbstractElectrochemical scanning tunneling microscopy (ECSTM) has been used to examine the adlayer of octa‐alkoxy‐substituted copper(II) phthalocyanines (CuPc(OC8H17)8) on Au(111) in 0.1 M HClO4, where the molecular adlayer was prepared by spontaneous adsorption from a benzene solution containing this molecule. Topography STM scans revealed long‐range ordered, interweaved arrays of CuPc(OC8H17)8 with coexistent rectangular and hexagonal symmetries. High‐quality STM molecular resolution yielded the internal molecular structure and the orientation of CuPc(OC8H17)8 admolecules. These STM results could shed insight into the method of generating ordered molecular assemblies of phthalocyanine molecules with long‐chained substitutes on metal surface. Microsc. Res. Tech., 2008. © 2007 Wiley‐Liss, Inc.
Three‐dimensional refractive index reconstruction with quantitative phase tomography
Authors: Dragomir N.M. , Goh X.M. , Roberts A. 
Published: September 2007

AbstractOptical tomography based on quantitative phase microscopy is used to determine nondestructively and with high spatial resolution the three‐dimensional (3D) refractive index distributions within optical fiber devices. After obtaining a series of phase images of the fiber as it is rotated around its longitudinal axis at regularly‐spaced angular positions, filtered backprojection is used to reconstruct a 3D map of the refractive index. The 3D refractive index distribution of the join region between two fusion spliced optical fibers is reconstructed with accuracy better than 10−3. Microsc. Res. Tech., 2008. © 2007 Wiley‐Liss, Inc.
Measuring the energy expenditure and water flux in free‐ranging alpacas (Lama pacos) in the peruvian andes using the doubly labelled water technique
Authors: Riek Alexander , Van Der Sluijs Leendert , Gerken Martina 
Published: September 2007

AbstractEnergy expenditure and water flux were measured in free‐ranging alpacas Lama pacos, a South American camelid, on natural pastures of the Peruvian Andes (altitude: 4,400 m above sea level). Water influx rate (WIR) was estimated in 16 males (age 2 years, weight 48.5±8.6 kg) labelled with 2H. In addition, the field metabolic rate (FMR) was measured in four of these animals labelled with both an oxygen (18O) and a hydrogen (2H) isotope. The WIR averaged 3.62 L H2O/day and the mean total body water 33.1 kg, equal to 68.2% of body weight (BW). The FMR of the four doubly labelled animals was 14.05 MJ/day. New allometric equations were calculated describing the relationships between WIR or FMR and BW, respectively, including published data on ruminants and the present alpaca results. The regression equation indicates that daily WIR scales to a similar metabolic size (kilograms of BW0.94) in alpacas than in wild or domesticated ruminants and camelids originating from arid and semiarid habitats. The resulting regression equation for FMR explained over 99% of the variation and corresponded to the function FMR (kilojoules per day)=1079 (kilograms of BW0.668) (n=5, r2=0.995, P<0.001). The FMR measured in this study, the first reported for a South American camelid species, suggests that free‐ranging alpacas have similar energy expenditures on a metabolic weight basis as other wild ruminants living under harsh climatic conditions. J. Exp. Zool. 307A:667–675, 2007. © 2007 Wiley‐Liss, Inc.
Temperature‐induced gene expression associated with different thermal reaction norms for growth rate
Authors: Ellers Jacintha , Mariën Janine , Driessen Gerard , van Straalen Nico M. 
Published: September 2007

AbstractAlthough nearly all organisms are subject to fluctuating temperature regimes in their natural habitat, little is known about the genetics underlying the response to thermal conditions, and even less about the genetic differences that cause individual variation in thermal response. Here, we aim to elucidate possible pathways involved in temperature‐induced phenotypic plasticity of growth rate. Our model organism is the collembolanOrchesella cinctathat occurs in a wide variety of habitats and is known to be adapted to local thermal conditions. Because sequence information is lacking inO. cincta, we constructed cDNA libraries enriched for temperature‐responsive genes using suppression subtractive hybridization. We compared gene expression ofO. cinctawith steep thermal reaction norms (high plasticity) to those with flat thermal reaction norms (low plasticity) for juvenile growth after exposure to a temperature switch composed of a cooling or a warming treatment. Using suppression subtractive hybridization, we found differential expression of ten nuclear genes, including several genes involved in energy metabolism, such as pantothenate kinase and carbonic anhydrase. In addition, seven mitochondrial genes were found in the cloned subtracted library, but further analysis showed this was caused by allelic variation in mitochondrial genes in our founder population, and that a specific haplotype was associated with high thermal responsiveness. Future work will focus on candidate genes from pathways such as the oxidative phosphorylation and biosynthesis of coenzyme A which are possibly involved in thermal responsiveness of juvenile growth rate.J. Exp. Zool. (Mol. Dev. Evol.) 310B:137–147, 2008. © 2007 Wiley‐Liss, Inc.
Oogenesis in four species of Piscicola (Hirudinea, Rhynchobdellida)
Authors: Spałek‐Wołczyńska Aleksandra , Klag Jerzy , Bielecki Aleksander , Świątek Piotr 
Published: September 2007

AbstractPiscicola has a pair of elongated sac‐shaped ovaries. Inside the ovaries are numerous small somatic cells and regularly spherical egg follicles. Each follicle is composed of three types of cells: many (average 30) germ cells (cystocytes) interconnected by intercellular bridges in clones (cysts), one intermediate cell, and three to five outer follicle cells (envelope cells). Each germ cell in a clone has one intercellular bridge connecting it to the central anucleate cytoplasmic mass, the cytophore. Each cluster of germ cells is completely embedded inside a single huge somatic follicle cell, the intermediate (interstitial) cell. The most spectacular feature of the intermediate cell is its development of a system of intracytoplasmic canals apparently formed of invaginations of its cell membrane. Initially the complex of germ cell cluster + intermediate cell is enclosed within an envelope composed of squamous cells. As oogenesis progresses the envelope cells gradually degenerate. All the germ cells that have terminated their mitotic divisions are of similar size and enter meiotic prophase, but one of the cystocytes promptly starts to grow faster and differentiates into the oocyte, whereas the remaining cystocytes withdraw from meiosis and become nurse cells (trophocytes). Numerous mitochondria, ER, and a vast amount of ribosomes are transferred from the trophocytes via the cytophore toward the oocyte. Eventually the oocyte ingests all the content of the cytophore, and the trophocytes degenerate. Little vitellogenesis takes place; the oocyte gathers nutrients in the form of small lipid droplets. At the end of oogenesis, an electron‐dense fibrous vitelline envelope appears around the oocyte, among short microvilli. At the same time, electron‐dense cortical granules occur in the oocyte cortical cytoplasm; at the end of oogenesis they are numerous, but after fertilization they disappear from the ooplasm. In the present article we point out many differences in the course of oogenesis in two related families of rhynchobdellids: piscicolids and glossiphoniids. J. Morphol., 2008. © 2007 Wiley‐Liss, Inc.
Ultrastructure of the digestive tract in Acarus siro (Acari: Acaridida)
Authors: Šobotník Jan , Alberti Gerd , Weyda František , Hubert Jan 
Published: September 2007

AbstractThe gut of the mite Acarus siro is characterized on the ultrastructural level. It consists of the foregut (pharynx, esophagus), midgut (ventriculus, caeca, colon, intercolon, postcolonic diverticula, postcolon), and hindgut (anal atrium). The gut wall is formed by a single‐layered epithelium; only regenerative cells are located basally and these have no contact with the lumen. Eight cell types form the whole gut: (i) simple epithelial cells forming fore‐ and hindgut; (ii) cells that probably produce the peritrophic membrane; (iii) regenerative cells occurring in the ventriculus, caeca, colon, and intercolon; (iv) spherite cells and (v) digestive cells forming the ventriculus and caeca; (vi) colonic cells and (vii) intercolonic cells; and (viii) cells forming the walls of postcolonic diverticula and postcolon. Spherite and digestive cells change in structure during secretory cycles, which are described and discussed. The cycle of spherite, colonic, and intercolonic cells is terminated by apoptosis. Ingested food is packed into a food bolus surrounded by a single homogeneous peritrophic membrane formed by addition of lamellae that subsequently fuse together. The postcolonic diverticula serve as a shelter for filamentous bacteria, which also are abundant in the intercolon. J. Morphol., 2008. © 2007 Wiley‐Liss, Inc.
Cell dynamic adhesion and elastic properties probed with cylindrical atomic force microscopy cantilever tips
Authors: Rico Félix , Roca‐Cusachs Pere , Sunyer Raimon , Farré Ramon , Navajas Daniel 
Published: September 2007

AbstractCell adhesion is required for essential biological functions such as migration, tissue formation and wound healing, and it is mediated by individual molecules that bind specifically to ligands on other cells or on the extracellular matrix. Atomic force microscopy (AFM) has been successfully used to measure cell adhesion at both single molecule and whole cell levels. However, the measurement of inherent cell adhesion properties requires a constant cell–probe contact area during indentation, a requirement which is not fulfilled in common pyramidal or spherical AFM tips. We developed a procedure using focused ion beam (FIB) technology by which we modified silicon pyramidal AFM cantilever tips to obtain flat‐ended cylindrical tips with a constant and known area of contact. The tips were validated on elastic gels and living cells. Cylindrical tips showed a fairly linear force–indentation behaviour on both gels and cells for indentations >200 nm. Cylindrical tips coated with ligands were used to quantify inherent dynamic cell adhesion and elastic properties. Force, work of adhesion and elasticity showed a marked dynamic response. In contrast, the deformation applied to the cells before rupture was fairly constant within the probed dynamic range. Taken together, these results suggest that the dynamic adhesion strength is counterbalanced by the dynamic elastic response to keep a constant cell deformation regardless of the applied pulling rate. Copyright © 2007 John Wiley & Sons, Ltd.