bluuebunny/crossref_metadata_2025_split huggingface dataset:
Propene Polymerization with Bis(phenoxy–imine) Group 4 Transition Metal Complexes
Authors: Makio Haruyuki , Fujita Terunori 
Published: January 2005

Abstract
Olefin polymerizations with group 4 transition metal complexes having two phenoxy–imine ligands (FI Catalysts) are reviewed with an emphasis on the characteristics and mechanisms of propene polymerization. The structures and properties of FI Catalysts can be easily modified by changing phenoxy–imine ligand structures. Such catalysts can be synthesized straightforwardly from readily available chemicals. An enormous library of FI Catalysts can be built up by combining a group 4 metal center and a variety of cocatalysts. The diversified library makes FI Catalysts so versatile that polyolefins with desired properties (molecular weight, molecular weight distribution, chain-end structure, tacticity, and so on) can be obtained sometimes predictably, by selecting the appropriate combination of ligand, metal, and cocatalyst. In propene polymerization, it remains a challenge to control the stereo- and regiochemistry of monomer enchainment in order to obtain commercially valuable products. FI Catalysts can produce syndiotactic and isotactic polypropene by Ti–FI catalysts/MAO and Zr– and Hf–FI catalysts/iBu3Al/Ph3CB(C6F5)4, respectively. Because of the well-defined and tunable nature of the catalysts, the coordination environment around the metal center can be controlled by the ligand structures to achieve extremely high stereoregularities, comparable to those of heterogeneous Ziegler–Natta catalysts and metallocene catalysts. These syndio- and isospecific FI Catalysts have contrasting reaction mechanisms, i.e., the syndiospecific polymerization is mediated via 2,1-insertion under chain-end control, while isospecificity arises from 1,2-insertion and a site control mechanism. The observed syndiospecificity can originate from the inherent fluxionality of FI Catalysts between configurational isomers.
Preparation of Spherical Particles with Quartz Single Crystal
Authors: Okabayashi Minahiro , Miyazaki Kenji , Kono Toshio , Tanaka Miyoko , Toda Yumio 
Published: January 2005

Abstract
Spherical particles with α-quartz single crystal were obtained from amorphous silica by heating in the atmospheric pressure. The silica particles containing a small amount of titanium oxide and calcium oxide were prepared from metal alkoxides and then were heated at 1000 °C in the atmospheric pressure. The resulting particle was determined to be a single crystal by means of a transmission electron microscopy and electron diffractometry.
Enhanced Efficiency and Regioselectivity of Intramolecular (2π + 2π) Photocycloaddition of 1-Cyanonaphthalene Derivative Using Microreactors
Authors: Maeda Hajime , Mukae Hirofumi , Mizuno Kazuhiko 
Published: January 2005

Abstract
The intramolecular photocycloaddition of a 1-cyanonaphthalene derivative in microreactors made of poly(dimethylsiloxane) (PDMS) was examined. By using the microreactors and flow system, both the efficiency and regioselectivity increased compared with those under batch conditions.
Bis(ethylenedioxy)-1,4,5,8-tetraselenanaphthalene: The First Example of Tetraselenanaphthalene
Authors: Watanabe Ryoji , Miyake Yoshihiro , Kuwatani Yoshiyuki , Iyoda Masahiko 
Published: January 2005

Abstract
The titled tetraselenanaphthalene derivative (BEDO-TSeN) has been synthesized using the reaction of 1,4-dioxene-2,3-diselenolate with tetraiodo- or tetrabromoethylene. The structure of this tetraselenanaphthalene derivative was confirmed by X-ray analysis. The π-donor property of this molecule was determined by CV analysis.
Lithium Acetate-catalyzed Trifluoromethylation of Carbonyl Compounds with (Trifluoromethyl)trimethylsilane
Authors: Mukaiyama Teruaki , Kawano Yoshikazu , Fujisawa Hidehiko 
Published: January 2005

Abstract
Trifluoromethylation of various aldehydes and ketones with (trifluoromethyl)trimethylsilane in the presence of a catalytic amount of a Lewis base such as lithium acetate proceeded smoothly to afford the corresponding trifluoromethylated adducts in good to high yields.
Liquid fraction in stratiform mixed‐phase clouds from in situ observations
Authors: Boudala Faisal S. , Isaac George A. , Cober Stewart G. , Fu Qiang 
Published: January 2005

AbstractLiquid fractions in mixed‐phase clouds have been analysed using aircraft measurements taken in mid‐ and high latitude stratiform clouds. The liquid fraction generally increases with temperature but has a minimum at about −15°C, where the maximum ice crystal growth based on vapour deposition would be expected. The mean liquid fraction also depends on total water content. This suggests that segregation of cloud phase based on a simple linear relationship of phase fraction (ice or liquid) with temperature, as is used in some climate models, may be unrealistic. Parametrizations of mean liquid fraction in terms of temperature and total water content, and in terms of temperature alone, have been developed based on data averaged at 10 s resolution (1 km). These parametrizations agree reasonably well with the observations. Copyright © 2004 Royal Meteorological Society
Influence‐matrix diagnostic of a data assimilation system
Authors: Cardinali Carla , Pezzulli Sergio , Andersson Erik 
Published: January 2005

AbstractThe influence matrix is used in ordinary least‐squares applications for monitoring statistical multiple‐regression analyses. Concepts related to the influence matrix provide diagnostics on the influence of individual data on the analysis—the analysis change that would occur by leaving one observation out, and the effective information content (degrees of freedom for signal) in any sub‐set of the analysed data. In this paper, the corresponding concepts have been derived in the context of linear statistical data assimilation in numerical weather prediction. An approximate method to compute the diagonal elements of the influence matrix (the self‐sensitivities) has been developed for a large‐dimension variational data assimilation system (the four‐dimensional variational system of the European Centre for Medium‐Range Weather Forecasts). Results show that, in the boreal spring 2003 operational system, 15% of the global influence is due to the assimilated observations in any one analysis, and the complementary 85% is the influence of the prior (background) information, a short‐range forecast containing information from earlier assimilated observations. About 25% of the observational information is currently provided by surface‐based observing systems, and 75% by satellite systems.Low‐influence data points usually occur in data‐rich areas, while high‐influence data points are in data‐sparse areas or in dynamically active regions. Background‐error correlations also play an important role: high correlation diminishes the observation influence and amplifies the importance of the surrounding real and pseudo observations (prior information in observation space). Incorrect specifications of background and observation‐error covariance matrices can be identified, interpreted and better understood by the use of influence‐matrix diagnostics for the variety of observation types and observed variables used in the data assimilation system. Copyright © 2004 Royal Meteorological Society
Textural Properties and Adsorption of Dyes onto Carbons Derived from Cotton Stalks
Authors: Attia Amina A. , El-Hendawy Abdel-Nasser A. , Khedr Soheir A. , El-Nabarawy Th. 
Published: January 2005

Non-activated carbon ‘C’, zinc chloride-activated carbon ‘Z’ and steam-activated carbon ‘S’ were prepared from cotton stalks available as an agricultural waste. These carbon adsorbents were investigated to determine their texture and their potential for dye adsorption. Cotton stalks after chopping, washing and drying were also investigated as an additional adsorbent, designated ‘P’. The textural properties (surface area and porosity) of the sorbents were determined from the low-temperature adsorption of nitrogen at −196°C by carefully analyzing their nitrogen adsorption isotherms. The adsorption of Methylene Blue (MB) and Congo Red (CR) at 30, 40 and 50°C was investigated via kinetic and equilibrium adsorption measurements. Activated carbons ‘Z’ and ‘S’ exhibited high surface areas and high total pore volumes and possessed high dye uptakes. Non-activated carbon ‘C’ possessed a lower but satisfactory dye uptake while the raw material ‘P’ exhibited the lowest dye uptake. The adsorption of MB and CR was controlled by pore diffusion and followed first-order kinetics. The adsorption of the two dyes decreased with increasing adsorption temperature. The adsorption of both MB and CR was associated with a decrease in ΔG but with an increase in ΔS.
Family genetic studies, suicide, and suicidal behavior
Authors: Brent David A. , Mann J. John 
Published: January 2005

AbstractThe extant adoption, twin, and family studies of suicide and suicidal behavior are reviewed. Suicidal behavior is highly familial, and on the basis of twin and adoption studies, heritable as well. Both completed and attempted suicide form part of the clinical phenotype that is familially transmitted, as rates of suicide attempt are elevated in the family members of suicide completers, and completion rates are elevated in the family members of attempters. A family history of suicidal behavior is associated with suicidal behavior in the proband, even after adjusting for presence of psychiatric disorders in the proband and family, indicating transmission of attempt that is distinct from family transmission of psychiatric disorder. Impulsive aggression in probands and family members is associated with family loading for suicidal behavior, and may contribute to familial transmission of suicidal behavior. Shared environment effects such as abuse, imitation, or transmission of psychopathology are other possible explanations. © 2005 Wiley‐Liss, Inc.
Synthesis and characterization of hydroxyethyl methacrylate/acrylamide responsive hydrogels
Authors: Nizam El‐Din Horia M. , El‐Naggar Abdel Wahab M. 
Published: January 2005

AbstractHydrogels based on an aqueous solution of hydroxyethyl methacrylate (HEMA) and acrylamide (AM) in the presence of trithioglycolic acid (TTGA) were prepared under the effect of gamma irradiation. These hydrogels were characterized by IR spectroscopy and thermogravimetric analysis and investigated for temperature‐ and pH‐responsive materials. It was found that TTGA is essential for the formation of HEMA/AM hydrogels at different compositions, in which the gel fraction depends on composition. A binary mixture of HEMA and AM at equal ratios was the critical composition that forms hydrogels, even in the presence of TTGA. The IR spectroscopic analysis showed that the formation of hydrogels depends on hydrogen bonding and crosslinking. The TGA investigations with respect to mass loss and the temperatures of the maximum value of the rate of reaction showed that HEMA/AM hydrogels possess higher thermal stability than that of pure HEMA and this stability increases with increasing ratio of the AM component. Also, it was observed that the temperature of the maximum value of the rate of thermal decomposition reaction depends on hydrogel composition. However, calculations of the activation energy showed that the hydrogel composed of 90% HEMA and 10% AM exhibits the highest thermal stability during the increasing or decreasing rate of reaction. Kinetic studies of swelling in water showed that HEMA/AM hydrogels displayed a temperature‐responsive character within the temperature range 25–30°C, and showed a stepwise swelling behavior in the pH range 2–10, depending on composition. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1105–1115, 2005
Preparation, characterization, and water‐sorption study of polyvinyl alcohol based hydrogels with grafted hydrophilic and hydrophobic segments
Authors: Shukla Sandeep , Bajpai A. K. , Kulkarni R. A. 
Published: January 2005

AbstractThe interpenetrating polymer network hydrogels based on poly(vinyl alcohol) were obtained by graft copolymerization of acrylamide and styrene onto polyvinyl alcohol in the presence of N,N′‐methylene bisacrylamide as a crosslinking agent. The hydrogels were characterized by optical microscopy, scanning electron microscopy, infrared spectral analysis, differential scanning calorimeter, and thermogravimetric analysis. The hydrogels showed enormous swelling in aqueous medium and displayed swelling characteristics, which were highly dependent on the chemical composition of the hydrogels and pH of the swelling medium. The kinetics of water uptake and the mechanisms of water transport were studied as a function of composition of the hydrogel and pH of the swelling medium. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1129–1142, 2005
Fabrication of a gradient refractive index preform using laminar shear mixing
Authors: Choi Jin Sung , Im Sang Hyuk , Song Min Young , Park O Ok , Cho Hansol , Hwang Jin Taek 
Published: January 2005

AbstractA gradient refractive index rod was successfully prepared by a new fabrication method using laminar shear mixing, and a graded index polymer optical fiber that satisfied IEEE1394b was obtained from the method. To fabricate the gradient refractive index rod, a liquid monomer mixture with a relatively low refractive index was placed in a prepared cylindrical glass reactor and a transparent polymer rod with a higher refractive index was introduced at the center of the reactor. The reactor and the polymer rod were then rotated concurrently with a small rotating speed difference to generate a Couette flow in the liquid phase. The centrifugal force generated by rotation and the polymer diffusion into the liquid monomer mixture developed a graded concentration profile in a radial direction. The Couette flow could reduce the concentration fluctuation in a tangential direction. In addition, the graded index profile could be controlled by the copolymer composition of the rod and its diameter. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1100–1104, 2005
Adsorption of biopolymers at hydrophilic cellulose–water interface
Authors: Halder Ebrahim , Chattoraj D. K. , Das K. P. 
Published: January 2005

AbstractThe extent of adsorption (Γ) of bovine serum albumin (BSA), β‐lactoglobulin, lysozyme, gelatin, and DNA from aqueous solution onto the hydrophilic surface of cellulose has been measured as function of biopolymer concentration at different temperatures, pHs, and ionic strengths, and in the presence of a high concentration of inorganic salts and denaturants. In all cases, the value of Γ increases with the increase of biopolymer concentration (X2) in bulk and it attains a maximum value at a critical mole fraction concentration X. The value of Γ depends upon the nature of protein, temperature, pH, and ionic strength, as well as the nature of neutral salts present in excess. Γ for proteins at a fixed physicochemical condition stands in the following order:

The isotherms for adsorption of DNA nucleotides on cellulose surface at pH 4.0 have been compared at different temperatures and ionic strengths, and in the presence of high concentration of inorganic salts LiCl, NaCl, KCl, and Na2SO4. Values of Γ for different systems have been evaluated and critically compared. At pH 6.0 and 8.0, Γ values of DNA nucleotides on cellulose are all negative due to the excess positive hydration of cellulose. At pH 4.0, adsorption of nucleotides of acid, alkali, and heat‐denatured DNA widely differ from each other and in the presence of excess concentration of urea becomes negative. The probable mechanisms of biopolymer–cellulose adsorption in terms of polymer hydration, steric interaction, London–van der Waals, hydrophobic, and other types of interactions have been discussed qualitatively. The standard free energy change for the adsorption of protein and DNA nucleotides on the cellulose surface at the state of adsorption saturation has been calculated in kJ per kg of cellulose using an integrated form of the Gibbs adsorption equation. The relation between ΔG° and maximum affinities between biopolymers and the polysaccharide interface have been discussed for various systems. © 2005 Wiley Periodicals, Inc. Biopolymers 77: 286–295, 2005
Effect of ionic strength on the organization and dynamics of tryptophan residues in erythroid spectrin: A fluorescence approach
Authors: Kelkar Devaki A. , Chattopadhyay Amitabha , Chakrabarti Abhijit , Bhattacharyya Malyasri 
Published: January 2005

AbstractThe ionic strength of the medium plays an important role in the structure and conformation of erythroid spectrin. The spectrin dimer is a flexible rod at physiological ionic strength. However, lower ionic strength results in elongation and rigidification (stiffening) of spectrin as shown earlier by electron microscopy and hydrodynamic studies. The ionic strength induced structural transition does not involve any specific secondary structural changes. In this article, we have used a combination of fluorescence spectroscopic approaches that include red edge excitation shift (REES), fluorescence quenching, time‐resolved fluorescence measurements, and chemical modification of the spectrin tryptophans to assess the environment and dynamics of tryptophan residues of spectrin under different ionic strength conditions. Our results show that while REES, fluorescence anisotropy, lifetime, and chemical modification of spectrin tryptophans remain unaltered in low and high ionic strength conditions, quenching of tryptophan fluorescence by the aqueous quencher acrylamide (but not the hydrophobic quencher trichloroethanol) and resonance energy transfer to a dansyl‐labeled fatty acid show differences in tryptophan environment. These results, which report tertiary structural changes in spectrin upon change in ionic strength, are relevant in understanding the molecular details underlying the conformational flexibility of spectrin. © 2005 Wiley Periodicals, Inc. Biopolymers 77: 325–334, 2005
Unstructured moving grids for implicit calculation of unsteady compressible viscous flows
Authors: Jahangirian A. , Hadidoolabi M. 
Published: January 2005

AbstractAn efficient dual‐time implicit approach combined with unstructured moving grids is presented to solve unsteady turbulent flows. Unstructured grids suitable for both inviscid and turbulent viscous flow regions are generated using a successive refinement method and the grid is moved adaptively based on the boundary movements. Special care is taken to maintain the quality of the grid near the surface. The unsteady two‐dimensional compressible Navier–Stokes equations are discretized by an implicit approach in a real time basis. The resulting set of implicit non‐linear equations is then solved iteratively in pseudo‐time using a Runge–Kutta scheme. The k–ε turbulence model equations are solved together with the main flow equations in a fully coupled manner. Results are presented for an unsteady transonic test case (AGARD CT5) about a NACA0012 oscillating airfoil and comparisons with experimental data showed good agreements. Copyright © 2005 John Wiley & Sons, Ltd.
DNA methylation 40 years later: Its role in human health and disease
Authors: Scarano Maria Irene , Strazzullo Maria , Matarazzo Maria Rosaria , D'Esposito Maurizio 
Published: January 2005

AbstractA long path, initiated more than 40 years ago, has led to a deeper understanding of the complexity of gene regulation in eukaryotic genomes. In addition to genetic mechanisms, the imbalance in the epigenetic control of gene expression may profoundly alter the finely tuned machinery leading to gene regulation. Here, we review the impact of the studies on DNA methylation, the “primadonna” in the epigenetic scenario, on the understanding of basic phenomena, such as X inactivation and genomic imprinting. The effect of deregulation of DNA methylation on human health, will be also discussed. Finally, an attempt to predict future directions of this rapidly evolving field has been proposed, with the certainty that, fortunately, science is always better than predictions. © 2005 Wiley‐Liss, Inc.
miR‐15a and miR‐16‐1 down‐regulation in pituitary adenomas
Authors: Bottoni Arianna , Piccin Daniela , Tagliati Federico , Luchin Andrea , Zatelli Maria Chiara , Degli Uberti Ettore C. 
Published: January 2005

AbstractMicro RNAs (miRs) are small noncoding RNAs, functioning as antisense regulators of other RNAs. miR‐15a and miR‐16‐1 genes are located at chromosome 13q14, a region which is frequently deleted in pituitary tumors. An inverse correlation has been shown in B cell chronic lymphocytic leukemia (B‐CLL) between miR‐15a and miR‐16‐1 expression and the expression levels of arginyl‐tRNA synthetase (RARS), an enzyme which associates with the cofactor p43 in the aminoacyl‐tRNA synthetase complex. When secreted, p43 regulates local inflammatory response and macrophage chemotaxis, and seems to have anti‐neoplastic properties in mice. We explored miR‐15a and miR‐16‐1 expression in 10 GH‐secreting and in 10 PRL‐secreting pituitary macroadenomas by Northern blot, and investigated the possible correlation with in vivo and in vitro characteristics. We found that miR‐15a and miR‐16‐1 are expressed at lower levels in pituitary adenomas as compared to normal pituitary tissue. Moreover, their expression inversely correlates with tumor diameter and with RARS expression (P < 0.05), but directly correlates with p43 secretion (P < 0.02). Therefore, miR15 and miR16 down‐regulation in pituitary adenomas correlates with a greater tumor diameter and a lower p43 secretion, suggesting that these genes may, at least in part, influence tumor growth. © 2005 Wiley‐Liss, Inc.
Porphyromonas gingivalis lipopolysaccharide induces shedding of syndecan‐1 expressed by gingival epithelial cells
Authors: Andrian Elisoa , Grenier Daniel , Rouabhia Mahmoud 
Published: January 2005

AbstractSyndecans are constitutively shed from growing epithelial cells as the part of normal cell surface turnover. However, increased serum levels of the soluble syndecan ectodomain have been reported to occur during bacterial infections. The aim of this study was to evaluate the potential of lipopolysaccharide (LPS) from the periodontopathogen Porphyromonas gingivalis to induce the shedding of syndecan‐1 expressed by human gingival epithelial cells. We showed that the syndecan‐1 ectodomain is constitutively shed from the cell surface of human gingival epithelial cells. This constitutive shedding corresponding to the basal level of soluble syndecan‐1 ectodomain was significantly increased when cells were stimulated with P. gingivalis LPS and reached a level comparable to that caused by phorbol myristic acid (PMA), an activator of protein kinase C (PKC) which is well known as a shedding agonist. The syndecan‐1 shedding was paralleled by pro‐inflammatory cytokine interleukin‐1 beta (IL‐1β), IL‐6, IL‐8, and tumor necrosis factor alpha (TNF‐α) release. Indeed, secretion of IL‐1β and TNF‐α increased following stimulation by P. gingivalis LPS and PMA, respectively. When recombinant forms of these proteins were added to the cell culture, they induced a concentration‐dependent increase in syndecan‐1 ectodomain shedding. A treatment with IL‐1β converting enzyme (ICE) specific inhibitor prevented IL‐1β secretion by epithelial cells stimulated by P. gingivalis LPS and decreased the levels of shed syndecan‐1 ectodomain. We also observed that PMA and TNF‐α stimulated matrix metalloproteinase‐9 secretion, whereas IL‐1β and P. gingivalis LPS did not. Our results demonstrated that P. gingivalis LPS stimulated syndecan‐1 shedding, a phenomenon that may be mediated in part by IL‐1β, leading to an activation of intracellular signaling pathways different from those involved in PMA stimulation. © 2005 Wiley‐Liss, Inc.