bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polar Cofacially Fixed Sandwich Complexes: Do They Demonstrate Second Harmonic Generation (SHG)?
Authors: Malessa Maik , Heck Jürgen , Kopf Jürgen , Garcia M. Helena 
Published: December 2005

AbstractFor the purpose of possible second harmonic generation (SHG) a cationic and a neutral sandwich unit were cofacially arranged in a three‐step synthesis starting from 1,8‐diiodonaphthalene. First, 1‐cyclopentadienyl‐8‐iodonaphthalene (2) was formed, then the neutral ferrocenyl substituent was fixed in the 8‐position by a Negishi cross‐coupling reaction. The deprotonation of the cyclopentadienyl substituent, and the subsequent coordination of the half‐sandwich fragments ML = [Fe(η5‐C5Me5)]+, [Rh(η5‐C5Me5)]2+, [Ir(η5‐C5Me5)]2+, [Ru(η6‐C6H6)]2+ to the cyclopentadienyl anion revealed the desired dinuclear complexes 1‐[(η5‐cyclopentadienediyl)(η5‐pentamethylcyclopentadienyl)iron(II)]‐8‐ferrocenylnaphthalene (5), 1‐[(η5‐cyclopentadienediyl)(η5‐pentamethylcyclopentadienyl)rhodium(III)]‐8‐ferrocenylnaphthalene hexafluorophosphate (6PF6), 1‐[(η5‐cyclopentadienediyl)(η5‐pentamethylcyclopentadienyl)iridium(III)]‐8‐ferrocenylnaphthalene hexafluorophosphate (7PF6), and 1‐[(η6‐benzene)(η5‐cyclopentadienediyl)ruthenium(II)]‐8‐ferrocenylnaphthalene hexafluorophosphate (8PF6). The neutral complex 5 was oxidized to the paramagnetic cation 1‐[(η5‐cyclopentadienediyl)(η5‐pentamethylcyclopentadienyl)iron(III)]‐8‐ferrocenylnaphthalene hexafluorophosphate (5PF6). Compounds 3, 5PF6, 6PF6, and 7PF6 were characterized by X‐ray structure determination; the neutral compound 3 crystallizes in the space group P21/c, whereas all of the cationic dinuclear complexes crystallize in the chiral space group C2221. A cyclic voltammetry study points to a predominant “through‐space” interaction between the cationic sandwich unit and the neutral ferrocene substituent. The compounds 5PF6, 6PF6, 7PF6, and 8PF6 were subjected to hyper‐Rayleigh scattering (HRS) and Kurtz‐powder measurements. In both studies no SHG intensity could be observed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Apolipoprotein E and obstructive sleep apnea: evaluating whether a candidate gene explains a linkage peak
Authors: Larkin Emma K. , Patel Sanjay R. , Redline Susan , Mignot Emmanuel , Elston Robert C. , Hallmayer Joachim 
Published: December 2005

AbstractEvidence from both linkage analyses and association‐based analyses has implicated Apoliprotein E (ApoE) as a disease susceptibility locus for obstructive sleep apnea. To further assess the putative role of ApoE in sleep apnea, we performed genotyping, association, and linkage analyses in a cohort assembled to investigate the genetic epidemiology of sleep apnea. Among a subset of the Caucasian families, ten microsatellites, spanning 20 cM, were genotyped in a region near ApoE on chromosome 19 where previous suggestive linkage had been demonstrated using a 9.1‐cM genome‐wide scan. Haseman‐Elston regression analysis, conducted with these fine mapping markers (n=196 sibling pairs, 56 families), showed evidence for linkage to marker AFM210yg9 (p=0.00034), which was increased over that observed with the original scan. ApoE genotyping also was performed on a larger set of data (n=1,211 from 271 families, ages 3–85 years) from the cohort with available DNA. To determine whether the ApoE genotype explains the linkage peak, we included the ApoE genotype as a covariate in regression models. Inclusion of ApoE E2 allele as a covariate reduced the regression coefficient by 18%, suggesting that ApoE does not substantively explain the linkage signal. Finally, we repeated an association‐based analysis in the larger sample of 1,211 individuals, and observed a higher prevalence of sleep apnea among individuals with the ApoE E2 allele. Overall, the evidence suggests that there is a disease susceptibility locus for obstructive sleep apnea in the region of ApoE, but ApoE itself is unlikely to be the causative locus. Genet. Epidemiol. 2006. © 2005 Wiley‐Liss, Inc.
Comparison study of a traditional pulsed dye laser versus a long‐pulsed dye laser in the treatment of early childhood hemangiomas
Authors: Kono Taro , Sakurai Hiroyuki , Groff William Frederick , Chan Henry H. , Takeuchi Masaki , Yamaki Takashi , Soejima Kazutaka , Nozaki Motohiro 
Published: December 2005

AbstractBackground and ObjectiveThe role of pulsed dye laser (PDL) in the treatment of childhood hemangiomas is still controversial because of the inherent characteristics of hemangiomas as well as the side effects of the PDL. Recently, the long pulsed dye laser (LPDL) with cryogen spray cooling (CSC) has been found relatively more effective and safer than the PDL in the treatment of port‐wine stains and telangiectasia. This study was designed to compare the efficacy and complication rate of PDL versus LPDL for treating childhood hemangiomas.Study Design/Materials and MethodsWe did a prospective, randomized, controlled trial in which we enrolled 52 Asian infants, aged 1–3 months, with early hemangiomas. These infants were assigned to PDL treatment (n = 26) or LPDL treatment (n = 26) and followed to age 1 year. A PDL with a wavelength of 585 nm and spot size of 7 mm and a LPDL with a wavelength of 595 nm and spot size of 7 mm were used. Each patient in the PDL group was treated with energy fluence between 6 and 7 J/cm2 and a pulse duration of 0.45 milliseconds without epidermal cooling. Each patient in the LPDL group was treated with energy fluence between 9 and 15 J/cm2 and a pulse duration of 10–20 milliseconds, utilizing CSC to protect the epidermis. Each group was treated at 4‐week intervals until the lesion cleared. When each patient reached an age of 1 year, outcome measures such as clearance rate, time period of maximum proliferation, and complications were assessed.ResultsThe number of children whose lesions showed complete clearance or minimal residual signs at 1 year of age was 14 (54%) in the PDL group and 17 (65%) in the LPDL group (P = 0.397). Compared with the LPDL, PDL treated children had more hypopigmentation (3, 12% vs. 8, 31%; P = 0.001), more hyperpigmentation (2, 8% vs. 4, 15%; P = 0.005), and more textural changes (1, 4% vs. 6, 23%; P = 0.001). The average time period of maximum proliferation in the LPDL group was significantly shorter than that of the PDL group (106 days vs. 177 days; P = 0.01).ConclusionEarly treatment of childhood hemangiomas with the LPDL is safer and more effective than the PDL. Lasers Surg. Med. 38:112–115, 2006. © 2005 Wiley‐Liss, Inc.
Lithium Ion Induced Stabilization of the Liquid Crystalline DNA
Authors: Sundaresan Neethu , Thomas Thresia , Thomas Thekkumkat John , Pillai Chennakkatu Krishna Saolashiuan 
Published: December 2005

AbstractSummary: A comparative study of the effects of alkali metal ions Li+, Na+, K+, Rb+, and Cs+ on the liquid crystalline organization of high‐molecular‐weight calf thymus DNA using polarized light microscopy was performed. Major differences in the behavior of Li+ as compared to the other ions were found. Critical DNA concentration expected to exhibit anisotropic behavior was found to be the same for all the monovalent ions, except for Li+. DNA initially showed cholesteric textures, which later changed to higher ordered columnar phase for all ions, with the cholesteric‐columnar transition facilitated upon increasing the size of the counterion. For Li+ ion, a nematic schlieren‐like texture was formed initially, which after a few days changed to a highly stable (for more than 2 months) biphasic cholesteric‐columnar arrangement. The observed differences between Li+ and other alkali metal ions could be rationalized on the basis of the higher number of hydration water molecules of Li+ and its complexation behavior. Highly stable DNA mesophases may find applications in the field of nanoelectronics, in designing biosensing units, and in DNA chips.Nematic schlieren‐like texture obtained in presence of Li+ ion after 5 h of incubation at 37 °C. Magnification 10×.magnified imageNematic schlieren‐like texture obtained in presence of Li+ ion after 5 h of incubation at 37 °C. Magnification 10×.
Triclosan Release from Coated Polyglycolide Threads
Authors: Zurita Raül , Puiggalí Jordi , Rodríguez‐Galán Alfonso 
Published: December 2005

AbstractSummary: Copolymerization of lactide, ε‐caprolactone, and trimethylene carbonate is performed. The synthesis is focused on obtaining materials with adequate properties for application as a suture coating that could contain an antimicrobial agent like triclosan. An amorphous character, a low glass transition temperature, a moderate susceptibility to degradation, and a hydrophobic nature are the conditions required for the optimal behavior of this coating. These properties can be attained with a copolymer of composition 10:60:30. Triclosan is added to the surface of polyglycolide threads and its release is studied in different media with high‐performance liquid chromatography. The influence of the temperature, the diameter of the thread, the initial concentration of the antibacterial agent, and the applied procedure on the incorporation of triclosan is also evaluated. A total release of triclosan is attained after a few days of exposure to a Dulbecco's based medium, whereas equilibrium concentrations are reached when a Sörensen hydrophilic medium is used. Partition and diffusion coefficients are also estimated.SEM of a braided polyglycolide thread coated with PLA/PCL/PTMC that incorporates triclosan (1%).magnified imageSEM of a braided polyglycolide thread coated with PLA/PCL/PTMC that incorporates triclosan (1%).
DNA‐Based Gels for Oral Delivery of Probiotic Bacteria
Authors: Jonganurakkun Benjamas , Nodasaka Yoshinobu , Sakairi Nobuo , Nishi Norio 
Published: December 2005

AbstractSummary: A single‐stranded DNA, readily extracted from industrial discarded salmon milt, was used to prepare hydrogels and complex gels by cross‐linking with gelatin and κ‐carrageenan, for the oral delivery of probiotic bacteria. The complex gels showed a higher protective capability over the hydrogels for approximately one log scale. However, the hydrogels were more stable during storage at 4 °C. The Lactobacillus and Lactococcus due to protection of the hydrogels could better tolerate to acid than the Bifidobacterium. Furthermore, food‐graded hydrogels were prepared and optimized to a similar protective capability for future applications.SEM of bacteria fixed in DNA‐based hydrogel and DNA‐based complex gel.magnified imageSEM of bacteria fixed in DNA‐based hydrogel and DNA‐based complex gel.
A Novel Epoxy Resin/CaCO3 Nanocomposite and its Mechanism of Toughness Improvement
Authors: Shi Quan , Wang Li , Yu Haojie , Jiang Song , Zhao Zhenrong , Dong Xiaochen 
Published: December 2005

AbstractSummary: In this work, epoxy resin/CaCO3 nanocomposites were prepared by in situ and inclusion polymerization. Nanoparticles with a size of 30–40 nm were dispersed efficiently in bisphenol‐A alkaline solution before polymerization and the dispersion could be kept in the resultant composite by a reaction that took place at the nanoparticle surface and among the nanoparticles when epichlorohydrin was added. Furthermore, the slightly conglomerated nanoparticles could even be separated by epoxy resin growing among them. This method showed a better dispersion of nanoparticles compared with solution‐blending as observed with TEM. Owing to better combination of epoxy resin and nanoparticles, the resultant nanocomposite showed a 12 °C increase in Tg compared to the nanocomposite prepared by solution‐blending. Tensile test revealed that the tensile strain of nanocomposites rises as the nano‐CaCO3 content increases.The dispersion mechanism of nanoparticles through in situ and inclusion polymerization.magnified imageThe dispersion mechanism of nanoparticles through in situ and inclusion polymerization.
Polypyrrole‐Fe3O4 Magnetic Nanocomposite Prepared by Ultrasonic Irradiation
Authors: Qiu Guihua , Wang Qi , Nie Min 
Published: December 2005

AbstractSummary: Ultrasonic irradiation was employed to prepare polypyrrole (PPY)/Fe3O4 magnetic nanocomposite by chemical oxidative polymerization of pyrrole in the presence of Fe3O4 nanoparticles. This approach can solve the problem in the dispersion and stabilization of inorganic nanoparticles in polymer. The structure and properties of PPY/Fe3O4 nanocomposite were characterized by TEM, XPS, FT‐IR, TG, and XRD. PPY deposits on the surface of Fe3O4 nanoparticles while Fe3O4 nanoparticles are dispersed at the nanoscale by ultrasonic irradiation, which leads to the formation of polypyrrole‐encapsulated Fe3O4 composite particles. The doping level of PPY in PPY/Fe3O4 nanocomposite is higher than that of neat PPY. The composites possess good electrical and magnetic properties. With the increase in the Fe3O4 content, the magnetization increases and the conductivity first increases and then decreases. When the Fe3O4 content is 40 wt.‐%, the conductivity reaches a maximum value of 11.26 S · cm−1, about nine times higher than that of neat PPY, and the saturation magnetization is 23 emu · g−1. Also, the introduction of Fe3O4 nanoparticles enhances the thermal stability of PPY/Fe3O4 composite.Conductivity of PPY/Fe3O4 composite at different Fe3O4 content.magnified imageConductivity of PPY/Fe3O4 composite at different Fe3O4 content.
Non‐Ionic, Poly(ethylene oxide)‐Based Surfactants as Intercalants/Dispersants/Exfoliants for Poly(propylene)‐Clay Nanocomposites
Authors: Moad Graeme , Dean Katherine , Edmond Lex , Kukaleva Natalia , Li Guoxin , Mayadunne Roshan T. A. , Pfaendner Rudolf , Schneider Armin , Simon George P. , Wermter Hendrik 
Published: December 2005

AbstractSummary: Poly(propylene) (PP)‐clay nanocomposites were prepared from unmodified montmorillonite clays (NaMMT), with poly(ethylene oxide)‐based nonionic surfactants as dispersants/intercalants/exfoliants. The primary objective of this research was to find dispersants that (a) allow PP nanocomposites to be formed by direct melt mixing; (b) are effective with unmodified clays and (c) comprise of only a minor component with respect to both the clay and the overall composition. Linear, branched, gemini and sugar‐based surfactants and structures containing poly(dimethyl siloxane) and poly(methyl methacrylate) blocks were examined. These additives were found to be effective in breaking down the clay agglomerates to tactoids, giving some expansion of the clay structure and partial exfoliation and providing substantially improved clay dispersion. The properties of the derived nanocomposites depend on the level of additive and its structure. Tensile and impact properties show significant improvement over the precursor PP. Also notable are the significantly better thermal and thermo‐oxidative stabilities, as compared to both PP and “clay alone” composites. For optimal properties, it is both necessary and desirable that the surfactant should only be a minor constituent (20–50%) of the composition, with respect to the clay. A preferred surfactant is linear PE‐block‐PEO, with a short PEO block and an alkyl chain with approximately 30 carbon atoms (C30).
magnified image
Untangling influences of hydrophobicity on protein sequences and structures
Authors: Yahyanejad Mehdi , Burge Christopher B. , Kardar Mehran 
Published: December 2005

AbstractWe perform a statistical analysis of solvent accessibility and hydrophobicity profiles of a representative set of proteins. The joint probability distribution is well fitted to a multivariable Gaussian, which takes a relatively simple form when expressed in terms of the Fourier transforms of the profiles. This allows us to quantify the asymmetric manner by which these profiles influence each other. For example, the α‐helix periodicity in sequence hydrophobicity is dictated by the solvent accessibility of structures, and not vice versa, possibly indicating the faster evolution of sequences compared to structures. The decorrelated hydrophobicity and solvent accessibility profiles show distinct behaviors at long periods, where sequence hydrophobicity fluctuates less, while solvent accessibility fluctuates more than average. The correlations between the two profiles can be interpreted as the Boltzmann weight of the solvation energy at room temperature, consistent with earlier observations. Proteins 2006. © 2005 Wiley‐Liss, Inc.
Structural variation and immune recognition of the P1.2 subtype meningococcal antigen
Authors: Tzitzilonis Christos , Prince Stephen M. , Collins Richard F. , Achtman Mark , Feavers Ian M. , Maiden Martin C. J. , Derrick Jeremy P. 
Published: December 2005

AbstractNeisseria meningitidis is a globally important cause of bacterial meningitis and septicemia. No comprehensive antimeningococcal vaccine is available, largely as a consequence of the high sequence diversity of those surface proteins that could function as components of a vaccine. One such component is the protein PorA, a major surface porin of this Gram‐negative organism that has been used in a number of experimental and licensed vaccines. Here we describe a series of experiments designed to investigate the consequences for antibody recognition of sequence diversity within a PorA antigen. The binding of a 14‐residue peptide, corresponding to the P1.2 subtype antigen, to the MN16C13F4 monoclonal antibody was sensitive to mutation of five out of the six residues within the epitope sequence. The crystal structure of the antibody Fab fragment, determined in complex with the peptide antigen, shows a remarkably hydrophobic binding site and interactions between the antigen and antibody are dominated by apolar residues. Nine intrachain hydrogen bonds are formed within the antigen which maintain the β‐hairpin conformation of the peptide. These hydrogen bonds involve residues that are highly conserved amongst different P1.2 sequence variants, suggesting that some positions may be conserved for structural reasons in these highly polymorphic regions. The sensitivity of antibody recognition of the antigen towards mutation provides a structural explanation for the widespread sequence variation seen in different PorA sequences in this region. Single point mutations are sufficient to remove binding capability, providing a rationale for the manner in which different meningococcal PorA escape variants arise. Proteins 2006. © 2005 Wiley‐Liss, Inc.
Prediction of protein stability changes for single‐site mutations using support vector machines
Authors: Cheng Jianlin , Randall Arlo , Baldi Pierre 
Published: December 2005

AbstractAccurate prediction of protein stability changes resulting from single amino acid mutations is important for understanding protein structures and designing new proteins. We use support vector machines to predict protein stability changes for single amino acid mutations leveraging both sequence and structural information. We evaluate our approach using cross‐validation methods on a large dataset of single amino acid mutations. When only the sign of the stability changes is considered, the predictive method achieves 84% accuracy—a significant improvement over previously published results. Moreover, the experimental results show that the prediction accuracy obtained using sequence alone is close to the accuracy obtained using tertiary structure information. Because our method can accurately predict protein stability changes using primary sequence information only, it is applicable to many situations where the tertiary structure is unknown, overcoming a major limitation of previous methods which require tertiary information. The web server for predictions of protein stability changes upon mutations (MUpro), software, and datasets are available at http://www.igb.uci.edu/servers/servers.html. Proteins 2006. © 2005 Wiley‐Liss, Inc.
Static secondary ion mass spectrometry for nanoscale analysis: surface characterisation of electrospun nanofibres
Authors: Van Royen Pieter , Schacht Etienne , Ruys Luc , Vaeck Luc Van 
Published: December 2005

AbstractThe viability of static secondary ion mass spectrometry (S‐SIMS) for selected applications of nanoscale analysis has been investigated, focusing on nanofibres produced by electrospinning (ES) as a test case. The samples consist of non‐woven nanowebs of which the individual fibres have diameters in the range of 100 nm. Use of solutions with functionalised polymers or polar additives potentially allows the surface composition to be tailored as a function of the application. So far nanowebs are primarily characterised by morphological examination. This paper describes the first detailed characterisation of molecular composition at the surface of nanofibres electrospun from poly(ε‐caprolactone) (PCL) solutions in acetone containing 0–15 mol% (relative to PCL) of cetyltrimethylammonium bromide (CTAB). Application of S‐SIMS to nanowebs has allowed mass spectra to be recorded containing the major diagnostic ions of both components. Their relative intensities point to surface enrichment and depletion of the polar CTAB additive relative to the PCL matrix for samples electrospun from solution containing low and high CTAB concentrations, respectively. Copyright © 2005 John Wiley & Sons, Ltd.
Validation of a gas chromatography/triple quadrupole mass spectrometry based method for the quantification of pesticides in food commodities
Authors: Vidal J. L. Martínez , Liébanas F. J. Arrebola , Rodríguez M. J. González , Frenich A. Garrido , Moreno J. L. Fernández 
Published: December 2005

AbstractA new multiresidue method has been validated in cucumber matrix for the routine analysis of 130 multiclass pesticide residues by gas chromatography/triple quadrupole mass spectrometry. The pesticides were extracted with ethyl acetate. A first identification of the pesticides was based on a tandem mass spectrometric (MS/MS) screening method, which monitors a single transition for each target compound, in less than 12 min. After that, potentially non‐negative samples were analyzed again by the MS/MS confirmation/quantification method, which monitors two or three MS/MS transitions for each compound, also in less than 12 min. Performance characteristics, such as trueness, precision, linear range, detection limit (LOD) and quantification limit (LOQ), for each pesticide were calculated. The average recoveries obtained ranged between 70 and 120% at three different fortification levels (25, 200 and 500 µg/kg) with precision, expressed as relative standard deviation (RSD), values lower than 15%. The calculated LOD and LOQ were typically <3.2 and 9.6 µg/kg, respectively. Such limits were much lower than the maximum residue levels (MRLs) established by European legislation. The proposed methodology was applied to the determination of pesticides in real vegetable samples from Almería (Spain). Copyright © 2005 John Wiley & Sons, Ltd.