bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prediction of Heterofullerene Stabilities: A Combined DFT and Chemometric Study of C56Pt2, C57Pt2and C81Pt2
Authors: Campanera Josep M. , Bo Carles , Balch Alan L. , Ferré Joan , Poblet Josep M. 
Published: February 2005

AbstractA systematic search of the regioisomers of the heterofullerenes, C57Pt2and C56Pt2, has been carried out by means of density functional calculations to find the most stable structures. Both heterofullerenes incorporate two metal atoms into the fullerene surface. In the case of C57Pt2, one platinum atom substitutes one carbon atom of C60and the other platinum atom replaces a CC bond, whereas in C56Pt2each platinum atom replaces one CC bond. Several geometric factors were studied, three of which have particularly important effects on the relative stabilities of the regioisomers: the PtPt separation, the number of CC bonds remaining after substitution, and the type of CC bond that is substituted. All these factors indicate that the deformation of the carbon framework is a general factor that governs the relative stabilities of the regioisomers. Because a high number of factors affect the stability of the heterofullerenes we also used chemometric techniques in this study. Partial least‐squares (PLS) regression was used to establish the structure–energy relationships of C57Pt2and C56Pt2heterofullerenes. The understanding gained of the factors that affect the relative isomers stabilities has allowed us to predict the stabilities of larger disubstituted carbon cages, for example, C81Pt2heterofullerene.
Structural Analysis of Chiral Complexes of Palladium(0) with 15‐Membered Triolefinic Macrocyclic Ligands
Authors: Pla‐Quintana Anna , Roglans Anna , de Julián‐Ortiz J. Vicente , Moreno‐Mañas Marcial , Parella Teodor , Benet‐Buchholz Jordi , Solans Xavier 
Published: February 2005

AbstractThe complete structural analysis of the palladium complexes of the triolefinic macrocycles (E,E,E)‐1,6,11‐tris(arylsulfonyl)‐1,6,11‐triazacyclopentadeca‐3,8,13‐trienes, which featured from three identical to three different aryl groups, was achieved by performing X‐ray diffraction studies, NMR spectroscopy, and other calculations. The stereochemical complexity is determined by the different isomers formed through complexation of the metal to one or other face of each of the three olefins involved. The palladacyclopropane formulation of the palladium–olefin interaction offers a clear picture of the stereogenicity of the olefin carbon atoms that are complexed to the metal. The energetically favorable isomers were identified in the solid‐state and in solution by performing X‐ray diffraction and NMR spectroscopic analysis, respectively.
An Experimental and Computational Study on the Effect of Al(OiPr)3 on Atom‐Transfer Radical Polymerization and on the Catalyst—Dormant‐Chain Halogen Exchange
Authors: Poli Rinaldo , Stoffelbach François , Maria Sébastien , Mata José 
Published: February 2005

AbstractCompound Al(OiPr)3 is shown to catalyze the halide‐exchange process leading from [Mo(Cp)Cl2(iPrNCHCHNiPr)] and CH3CH(X)COOEt (X=Br, I) to the mixed‐halide complexes [Mo(Cp)ClX(iPrNCHCHNiPr)]. On the other hand, no significant acceleration is observed for the related exchange between [MoX3(PMe3)3] (X=Cl, I) and PhCH(Br)CH3, by analogy to a previous report dealing with the RuII complex [RuCl2(PPh3)3]. A DFT computation study, carried out on the model complexes [Mo(Cp)Cl2(PH3)2], [MoCl3(PH3)3], and [RuCl2(PH3)3], and on the model initiators CH3CH(Cl)COOCH3, CH3Cl, and CH3Br, reveals that the 16‐electron RuII complex is able to coordinate the organic halide RX in a slightly exothermic process to yield saturated, diamagnetic [RuCl2(PH3)3(RX)] adducts. The 15‐electron [MoCl3(PH3)3] complex is equally capable of forming an adduct, that is, the 17‐electron [MoCl3(PH3)3(CH3Cl)] complex with a spin doublet configuration, although the process is endothermic, because it requires an energetically costly electron‐pairing process. The interaction between the 17‐electron [Mo(Cp)Cl2(PH3)2] complex and CH3Cl, on the other hand, is repulsive and does not lead to a stable 19‐electron adduct. The [RuCl2(PH3)3(CH3X)] system leads to an isomeric complex [RuClX(PH3)3(CH3Cl)] by internal nucleophilic substitution at the carbon atom. The transition state of this process for X=Cl (degenerate exchange) is located at lower energy than the transition state required for halogen‐atom transfer leading to [RuCl3(PH3)3] and the free radical CH3. On the basis of these results, the uncatalyzed halide exchange is interpreted as the result of a competitive SNi process, whose feasibility depends on the electronic configuration of the transition‐metal complex. The catalytic action of Al(OiPr)3 on atom‐transfer radical polymerization (and on halide exchange for the 17‐electron half‐sandwich MoIII complex) results from a more favorable Lewis acid–base interaction with the oxidized metal complex, in which the transferred halogen atom is bound to a more electropositive element. This conclusion derives from DFT studies of the model [Al(OCH3)3]n (n=1,2,3,4) compounds, and on the interaction of Al(OCH3)3 with CH3Cl and with the [Mo(Cp)Cl3(PH3)2] and [RuCl3(PH3)3] complexes.
Axonal development in the cerebral white matter of the human fetus and infant
Authors: Haynes Robin L. , Borenstein Natalia S. , Desilva Tara M. , Folkerth Rebecca D. , Liu Lena G. , Volpe Joseph J. , Kinney Hannah C. 
Published: February 2005

AbstractAfter completion of neuronal migration to form the cerebral cortex, axons undergo rapid elongation to their intra‐ and subcortical targets, from midgestation through infancy. We define axonal development in the human parietal white matter in this critical period. Immunocytochemistry and Western blot analysis were performed on 46 normative cases from 20–183 postconceptional (PC) weeks. Anti‐SMI 312, a pan‐marker of neurofilaments, stained axons as early as 23 weeks. Anti‐SMI 32, a marker for nonphosphorylated neurofilament high molecular weight (NFH), primarily stained neuronal cell bodies (cortical, subcortical, and Cajal‐Retzius). Anti‐SMI 31, which stains phosphorylated NFH, was used as a marker of axonal maturity, and showed relatively low levels of staining (approximately one‐fourth of adult levels) from 24–34 PC weeks. GAP‐43, a marker of axonal growth and elongation, showed high levels of expression in the white matter from 21–64 PC weeks and lower, adult‐like levels beyond 17 postnatal months. The onset of myelination, as seen by myelin basic protein expression, was ∼54 weeks, with progression to “adult‐like” staining by 72–92 PC weeks. This study provides major insight into axonal maturation during a critical period of growth, over an age range not previously examined and one coinciding with the peak period of periventricular leukomalacia (PVL), the major disorder underlying cerebral palsy in premature infants. These data suggest that immature axons are susceptible to damage in PVL and that the timing of axonal maturation must be considered toward establishing its pathology relative to the oligodendrocyte/myelin/axonal unit. J. Comp. Neurol. 484:156–167, 2005. © 2005 Wiley‐Liss, Inc.
Synaptogenesis on mature hippocampal dendrites occurs via filopodia and immature spines during blocked synaptic transmission
Authors: Petrak Lara J. , Harris Kristen M. , Kirov Sergei A. 
Published: February 2005

AbstractDuring development, dendritic spines emerge as stubby protrusions from single synapses on dendritic shafts or from retracting filopodia, many of which have more than one synapse. These structures are rarely encountered in the mature brain. Recently, confocal and two‐photon microscopy have revealed a proliferation of new filopodia‐like protrusions in mature hippocampal slices, especially when synaptic transmission was blocked. It was not known whether these protrusions have synapses nor whether they are accompanied by the other immature spine forms. Here, reconstruction from serial section electron microscopy (ssEM) was used to answer these questions. Acute hippocampal slices from mature male rats, ages 56 and 63 days, were maintained in vitro in control medium or in a nominally calcium‐free medium with high magnesium, glutamate receptor antagonists, and sodium and calcium channel blockers. At the end of each 8‐hour experiment, all slices were fixed, coded, and processed for ssEM. In agreement with light microscopy, there were more filopodia along dendrites in slices with blocked synaptic transmission. These filopodia were identified by their pointy tips and either the absence of synapses or presence of multiple synapses along them. There was also a proliferation of stubby spines. Filopodia along mature dendrites were typically shorter than developmental filopodia, with outgrowth likely being constrained by reduced extracellular space and compact neuropil, providing numerous candidate presynaptic partners in the vicinity of the mature dendrites. These findings suggest that synaptogenesis and spine formation are readily initiated under conditions of reduced activity in the mature brain. J. Comp. Neurol. 484:183–190, 2005. © 2005 Wiley‐Liss, Inc.
TGF‐β induces novel Lef‐1 splice variants through a Smad‐independent signaling pathway
Authors: Cordray Pauline , Satterwhite Daniel J. 
Published: February 2005

AbstractThe lymphoid enhancer‐binding factor (Lef‐1) transcription factor is best known for the ability to transduce Wnt signals during development and to mediate excessive Wnt signaling in certain types of cancer. We recently identified and characterized a novel Wnt‐like effect of transforming growth factor‐beta (TGF‐β) on β‐catenin, the binding partner of Lef‐1. Therefore, we sought to determine the effect of TGF‐β on expression of the Lef/T‐cell–specific transcription factor (TCF) components of the Wnt pathway. We found that TGF‐β markedly induced Lef‐1 mRNA expression in cell lines originating from fetal lung (Mv1Lu) and newborn skin (Balb/MK), tissues that normally express Lef‐1 during development. Lef‐1 induction was temporally related to but independent of TGF‐β–induced G1 cell cycle arrest. Furthermore, the induction of Lef‐1 was independent of both new protein synthesis and Smad‐mediated signaling. Using TGF‐β–treated Mv1Lu cells, we identified multiple splice forms of Lef‐1, including novel variants that lack both exons 2 and 3. We conclude that the induction of Lef‐1 has permissive effects on the well‐characterized TGF‐β signal that inhibits c‐myc expression and induces a G1 arrest. Developmental Dynamics 232:969–978, 2005. © 2005 Wiley‐Liss, Inc.
Metal‐Directed Stereoselective Syntheses of Homochiral Complexes of exo‐Bidentate Binaphthol Derivatives
Authors: Wang Ruihu , Xu Lijin , Ji Jianxin , Shi Qian , Li Yueming , Zhou Zhongyuan , Hong Maochun , Chan Albert S. C. 
Published: February 2005

AbstractThe homochiral exo‐bidentate ligands (S)‐2,2′‐bis(pyridylmethyleneoxy)‐1,1′‐binaphthyl [(S)‐L] and (R)‐2,2′‐bis(pyridylmethyleneoxy)‐1,1′‐binaphthyl [(R)‐L] were synthesized and employed for the preparation of coordination complexes with the aim of investigating the effect of an axially chiral 1,1′‐binaphthyl connector on self‐assembly process. Five homochiral complexes, [Ag{(S)‐L}(ClO4)]n (1), [Ag{(R)‐L}(ClO4)]n (2), [{Cd{(S)‐L}(H2O)Cl2}(H2O)0.5]n (3), [(Zn{(S)‐L}Cl2)(DMF)0.5(H2O)0.5]n (4), and [(Pd2{(S)‐L}2Cl4)(H2O)1.5]n (5), have been prepared and characterized by single‐crystal X‐ray diffraction analyses. The enantiomeric complexes 1 and 2 are isomorphous and are formed through interconnection of ligands and two‐coordinate AgI centers. Complex 3 possesses a similar structural framework to 1 and is formed with two nitrogen atoms from (S)‐L coordinating to six‐coordinate CdII in a trans mode. The interlocking in part of the adjacent, one‐dimensional helix‐like chains stabilizes its structure. Complex 4 is a one‐dimensional zigzag chain and is formed through interconnection of (S)‐L and ZnCl2 units. The exo‐bidentate (S)‐L ligand in 5 links square‐planar PdII into a homochiral dinuclear metallomacrocycle. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Stability and effectiveness against bacterial adhesion of poly(ethylene oxide) coatings in biological fluids
Authors: Roosjen Astrid , de Vries Joop , van der Mei Henny C. , Norde Willem , Busscher Henk J. 
Published: February 2005

AbstractPoly(ethylene oxide) (PEO) coatings have been shown to reduce the adhesion of different microbial strains and species and thus are promising as coatings to prevent biomaterial‐centered infection of medical implants. Clinically, however, PEO coatings are not yet applied, as little is known about their stability and effectiveness in biological fluids. In this study, PEO coatings coupled to a glass substratum through silyl ether bonds were exposed for different time intervals to saliva, urine, or phosphate‐buffered saline (PBS) as a reference at 37°C. After exposure, the effectiveness of the coatings against bacterial adhesion was assessed in a parallel plate flow chamber. The coatings appeared effective against Staphylococcus epidermidis adhesion for 24, 48, and 0.5 h in PBS, urine, and saliva, respectively. Using XPS and contact‐angle measurements, the variations in effectiveness could be attributed to conditioning film formation. The overall short stability results from hydrolysis of the coupling of the PEO chains to the substratum. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater
Nitrogen metabolism during synchronous growth of Chlorella pyrenoidosa. I. Protein amino acid distribution
Authors: Hare T. A. , Schmidt R. R. 
Published: February 2005

AbstractTotal cellular‐N, acid soluble‐N, lipid plus chlorophyll‐N, and the levels of the individual amino acids were measured during synchronous growth of a high temperature strain, 7‐11‐05, of Chlorella pyrenoidosa. Total cellular‐N increased exponentially except for a small but reproducible deviation from log‐linearity which occurred at approximately the middle of the 14 hour synchronous growth cycle. Although the level of acid soluble‐N (as % of total cellular‐N) exhibited definite periodism during synchronous growth, the amount of nitrogen in this pool was small (approximately 4–8%). Lipid‐ plus chlorophyll‐N showed only slight fluctuations during cellular development; however, the trend followed that previously observed for phospholipid‐P. The levels of the protein amino acids were expressed on a mole‐percentage basis of the total protein amino acids. The level of most of the protein amino acids remained essentially constant during the course of synchronous growth. The levels of the basic and acidic amino acids as well as alanine exhibited more significant periodism than the other protein amino acids. The total protein amino acid‐N level comprised approximately 63% of the total cellular‐N throughout cellular development.
The prolongation of homograft survival time in the platanna, Xenopus laevis laevis (Daudin), by exposure to low environmental temperature
Authors: Simnett John D. 
Published: February 2005

AbstractThe survival of autografts, first set homografts and second set homografts was compared at 9°C and at 25°C in immature but metamorphosed individuals. Exposure to low temperature prolonged the survival time of second set homografts to a lesser extent than that of first set homografts. It is concluded that low temperature prolongs the survival of first set homografts by inhibiting the process of immunological activation rather than by reducing the rate of reaction between sensitized host cells and the graft.
Properties of contractile protein from bovine carotid artery
Authors: Mallin Morton L. 
Published: February 2005

AbstractA contractile protein was isolated from the cow carotid artery by extracting with a medium containing 0.6 M KCL. The Enzymatic activity of the artery contractile protein resulted in the splitting of the terminal phosphate of ATP.Abbreviations: ATP for adenosine triphosphate; ATP‐ase for adenosine‐triphosphatase; R.F. for relaxing factor; AM for actomyosin; EDTA for ethylenediamine tetraacetic acid; TCA for tiechoroacetic acid; ηrel for relative viscosity; ηrel ATP for relative viscosity after addition of ATP.
The divalent metals Ca and Mg activated the enzyme with Ca showing the more pronounced activation. In addition to the studies on the ATP‐ase activity other properties were investigated, such as viscosity, solubility in KCL solutions, ATP‐induced synersis and sensitivity to relaxing factor. The properties of the contractile protein were those of actomyosin. The protein resembles uterine actomyosin with respect to its low ATP‐ase activity and its viscosity values of Zη and ATP sensitivity.
The relation between the torpor cycle and heat exchange in the California pocket mouse Perognathus californicus
Authors: Tucker Vance A. 
Published: February 2005

AbstractThe changes in body temperature (TB) associated with the torpor cycle of P. californicus are described by the equation \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{{\rm dT}_{\rm B} }}{{{\rm dt}}} = \frac{{{\rm heat production - heat loss}}}{{\rm K}} $\end{document} where t is time, and K is the heat capacity of body tissue. This equation can be solved after substituting appropriate expressions for maximum and minimum aerobic heat production and heat loss to give theoretical maximum rates of entry into and arousal from torpor.The measured time course of body temperature and oxygen consumption during entry into torpor compare favorably with theoretical curves calculated under conditions of minimum heat production and maximum heat loss. Thus P. californicus appears able to “switch off its thermostat” so that oxygen consumption during entry into torpor falls almost to the minimum level for a given body temperature. Heat loss during entry into torpor appears to be facilitated by an increase in thermal conductance.During arousal from torpor, body temperature increases faster than can be accounted for assuming maximum heat production and minimum heat loss. This could be explained by anaerobic heat production and by a decreased thermal conductance resulting from the posterior vasoconstriction typical of arousing hibernators.Torpor periods of short duration are feasible for P. californicus, for it can enter torpor and arouse immediately thereafter at an ambient temperature of 15° with an expenditure of energy only 55% of that required to maintain a high body temperature over the same period of time. Arousal from torpor at an ambient temperature of 15° requires about 75% of the total energy expended during a ten hour torpor cycle; entry into torpor and torpor itself account for only 9 and 16% of the total energy expenditure, respectively.The quantitative relations between heat production and heat loss presented in this paper suggest further investigations of the effects of body size on heat production and loss, and of physiological phenomena which alter heat exchange.
The effect of pyridoxal on potassium fluxes in the Ehrlich mouse ascites tumor cell
Authors: Hempling H. G. , Hare Daphne 
Published: February 2005

AbstractTo determine the extent of coupling between the transport of potassium and the transport of amino acids by the Ehrlich mouse ascites tumor cell, we have investigated the effect of pyridoxal on potassium fluxes. We have chosen a low concentration of pyridoxal (1 mM) known to increase the cell to medium ratios for glycine. It was found that pyridoxal reduced potassium efflux and influx in the steady‐state without significant change in oxygen consumption. At normal levels of cell potassium and in the steady‐state, glycine and pyridoxal together had no effect on potassium fluxes. However, when a net gain of potassium occurred as in a transfer of cells from low temperature to room temperature, glycine and pyridoxal together reduced influx, efflux, and net flux of the ion. In addition, glycine alone reduced potassium influx significantly in contrast to its stimulatory effect in the steady‐state. It is suggested that the steady‐state fluxes for potassium are a balance between an active influx and a passive mediated efflux. The active influx may be reduced in the presence of glycine while pyridoxal may exert its predominant effect on the passive efflux. To explain the stimulation of the influx and efflux of potassium by glycine in the steady‐state, it is hypothesized that the ion makes use of an exchange system for potassium under circumstances where glycine prevents the use of the pathway of active influx.
The action of bile salts on fluid and glucose movement by rat and hamster jejunum, in Vitro
Authors: Faust Robert G. , Wu Shih‐Min Liu 
Published: February 2005

AbstractEverted sacs of rat and hamster jejunum were used to measure, simultaneously, fluid and glucose movement in the presence of various concentrations of bile salts. Low concentrations of sodium taurocholate or glycocholate did not affect the rates of fluid absorption or transport by either rat or hamster jejunum. Under these conditions, in some cases, while glucose absorption was unaffected, glucose transport was inhibited. High concentrations of bile salts reduced fluid and glucose absorption and transport by both rat and hamster jejunum. Although the transport of glucose against a concentration gradient is completely inhibited at low concentrations of bile salts with rat jejunum, it still occurs with hamster jejunum even in the presence of high bile salt concentrations. In the absence of glucose in the incubation medium, the rates of fluid absorption by rat and hamster jejunum were greatly reduced. Under these conditions, fluid transport by rat jejunum was completely abolished, whereas fluid transport by hamster jejunum was greatly reduced, but not completely inhibited. However, addition of bile salts to the glucosefree incubation medium did produce a complete inhibition of fluid absorption and transport by both rat and hamster jejunum. Bile salts, within the concentration range used in this investigation, have no effect upon glucose utilization and lactic acid production by either rat or hamster jejunum. Sodium taurocholate and glycocholate, at the low concentration of 1 mM, reduced the ATP levels in both rat and hamster jejunal sacs. This reduction of ATP levels in whole sacs was also observed to occur in the mucosal layer in the presence of low concentrations of bile salts. A greater reduction in tissue ATP levels was observed when the bile salt concentration was increased. The amount of ATP in unincubated rat and hamster jejunum was reduced by approximately 40% when incubated in bicarbonate saline containing glucose. Tissue ATP levels were also reduced when sacs were incubated in a glucose‐free medium, a greater reduction being observed in rat jejunum. In the absence of glucose, bile salts were capable of decreasing ATP levels in hamster, but not in rat jejunum. The effects of bile salts on fluid and glucose movement by rat and hamster jejunum were discussed in relation to tissue energy sources for these processes. Also, the possible role played by bile salts in regulating the transference of various substances across the intestinal wall was discussed.