bluuebunny/crossref_metadata_2025_split huggingface dataset:
Best monotone M‐estimators
Authors: Kolkiewicz Adam W. 
Published: January 2007

AbstractThe author shows how to find M‐estimators of location whose generating function is monotone and which are optimal or close to optimal. It is easy to identify a consistent sequence of estimators in this class. In addition, it contains simple and efficient approximations in cases where the likelihood function is difficult to obtain. In some neighbourhoods of the normal distribution, the loss of efficiency due to the approximation is quite small. Optimal monotone M‐estimators can also be determined in cases when the underlying distribution is known only up to a certain neighbourhood. The author considers the e‐contamination model and an extension thereof that allows the distributions to be arbitrary outside compact intervals. His results also have implications for distributions with monotone score functions. The author illustrates his methodology using Student and stable distributions.
Self‐Rupturing and Hollow Microcapsules Prepared from Bio‐polyelectrolyte‐Coated Microgels
Authors: De Geest B. G. , Déjugnat C. , Prevot M. , Sukhorukov G. B. , Demeester J. , De Smedt S. C. 
Published: January 2007

AbstractThis paper reports on microcapsules obtained by layer‐by‐layer deposition of bio‐polyelectrolyte multilayers at the surface of biodegradable dextran microgels. The behavior of the layer‐by‐layer coating upon degradation of the microgel core strongly depends on the bio‐polyelectrolytes used. Two types of microcapsules, “self‐rupturing” microcapsules and “hollow” microcapsules, are presented. Self‐rupturing microcapsules are obtained when the swelling pressure of the degrading microgel core is strong enough to rupture the surrounding bio‐polyelectrolyte membrane. Self‐rupturing microcapsules could be of interest as a pulsed drug delivery system. Hollow microcapsules are obtained after applying multiple layers of bio‐polyelectrolyte that can withstand the swelling pressure of the degrading microgel core. Biomacromolecules (such as albumin and dextran) spontaneously accumulate in the hollow microcapsules prepared from dex‐HEMA microgels, which could be of interest for drug‐encapsulation purposes.
Guest‐Induced Chirality in the Ferrimagnetic Nanoporous Diamond Framework Mn3(HCOO)6
Authors: Zhang B. , Wang Z.‐M. , Kurmoo M. , Gao S. , Inoue K. , Kobayashi H. 
Published: January 2007

AbstractChiral magnets are obtained by inclusion of chiral guest molecules into the channels of an achiral nanoporous ferrimagnet consisting of the Mn3(HCOO)6 (1) framework. Insertion of the R or the S enantiomer of 2‐chloropropan‐1‐ol (CH3C*HClCH2OH) in the chiral pores of the previously emptied framework (space group P21/c) results in the two corresponding chiral solids (1R and 1S, space group P21), while insertion of a racemic mixture of the two enantiomers retains the achirality of the host for the meso solid (1RS, space group P21/c). The R guest is ordered in the M channels while the S guest is ordered in the P channels. In contrast, the R guests in the P channels and the S guests in the M channels are disordered on two crystallographic orientations. For the racemic mixture of the two enantiomers in 1RS, random disorder of guests in both channels is observed. Thus, the localization of the guest molecule depends on the nature of the surface to recognize the guest of a particular chirality. The guest inclusion compounds are thermally stable. The 1R and 1S compounds are optically active. All the compounds adopt a ferrimagnetic ground state. Compared to the host framework of 1 without guest, the Curie temperature decreases for both 1R and 1S but increases for 1RS. The additional interactions between the framework and the inserted guest alcohols strengthen the lattice via hydrogen bonds and other electrostatic forces, and it might account for the significant lowering of the lattice contribution as well as the magnetic component to the specific heat capacity upon guest loading.
Hybrid “Golden Fleece”: Synthesis and Catalytic Performance of Uniform Carbon Nanofibers and Silica Nanotubes Embedded with a High Population of Noble‐Metal Nanoparticles
Authors: Qian H.‐S. , Antonietti M. , Yu S.‐H. 
Published: January 2007

AbstractCarbon nanofibers produced by hydrothermal carbonization display remarkable reactivity and the capability for in situ loading with very fine noble‐metal nanoparticles of metals such as Pd, Pt, and Au. Large quantities of uniform carbon nanofibers embedded/confined with various kinds of noble‐metal nanoparticles can be easily prepared, resulting in the formation of the so‐called uniform and well‐defined “hybrid fleece” structures. In addition, a general method has been developed to synthesize uniform silica nanotubes embedded/confined with noble‐metal nanoparticles by using the “hybrid fleece” consisting of carbon nanofibers loaded with noble‐metal nanoparticles as a template. To the best of our knowledge, the filling of silica nanotubes with a dense population of noble‐metal nanoparticles has not been demonstrated so far. These hybrid carbon structures embedded with noble‐metal nanoparticles in a heterogeneous “fleece” geometry serve as excellent catalysts for a model reaction involving the conversion of CO to CO2 at low temperatures.
Tuning the Energy Level and Photophysical and Electroluminescent Properties of Heavy Metal Complexes by Controlling the Ligation of the Metal with the Carbon of the Carbazole Unit
Authors: Yang C. L. , Zhang X. W. , You H. , Zhu L. Y. , Chen L. Q. , Zhu L. N. , Tao Y. T. , Ma D. G. , Shuai Z. G. , Qin J. G. 
Published: January 2007

AbstractFour novel IrIII and PtII complexes with cyclometalated ligands bearing a carbazole framework are prepared and characterized by elemental analysis, NMR spectroscopy, and mass spectrometry. Single‐crystal X‐ray diffraction studies of complexes 1, 3, and 4 reveal that the 3‐ or 2‐position C atom of the carbazole unit coordinates to the metal center. The difference in the ligation position results in significant shifts in the emission spectra with the changes in wavelength being 84 nm for the Ir complexes and 63 nm for the Pt complexes. The electrochemical behavior and photophysical properties of the complexes are investigated, and correlate well with the results of density functional theory (DFT) calculations. Electroluminescent devices with a configuration of ITO/NPB/CBP:dopant/BCP/AlQ3/LiF/Al can attain very high efficiencies.
Raspberry‐like Gold Microspheres: Preparation and Electrochemical Characterization
Authors: Li Z. , Ravaine V. , Ravaine S. , Garrigue P. , Kuhn A. 
Published: January 2007

AbstractA straightforward method to synthesize quasi‐monodisperse gold microspheres from a commercial gold plating solution is reported. The size and the surface roughness of the obtained particles can easily be tuned. In particular, raspberry‐like particles with a high active surface area are obtained. The microspheres are assembled on indium tin oxide (ITO) electrodes using the layer‐by‐layer technique and the overall electroactive surface area is increased, as characterized by cyclic voltammetry. The as‐prepared products were characterized by scanning electron microscopy (SEM), powder X‐ray diffraction (XRD), cyclic voltammetry, and light microscopy.
Determination of radionuclides in water at uranium mining remediation – a comparison of analytical methods
Authors: Laubrich Jan , Lotze Petra , Winkler Gudrun 
Published: January 2007

AbstractThe corporate purpose of Wismut GmbH is to decommission its former mining holdings and to rehabilitate the landscape and the environment. Sample taking and analysing the value of contaminants are necessary steps for the remediation of waste rock piles, the recycling of contaminated areas, controlled flooding of uranium mines. Main emphasis lies on the determination of heavy metals and radionuclides of natural decay chains of U‐238 and U‐235. Yearly about 60 000…70 000 determinations of radionuclides in waters were done. Facing this high output of determinations it is a permanent task for laboratory and quality management to ask: Are the results of different methods comparable to each other? Is there a preferred analytical technology? Which matrix influences exist? and What about the analytical costs? Answers to these important questions are given in this report. Summarizing our investigations done in the last few years it is possible to say that – by using different analytical methods the results of radionuclides in water samples (surface or groundwater) are comparable, – a not negligible influence of Ra‐223, Ra‐224 and Ra‐228 may exist by using the DIN 38404 C18 method to determine Ra‐226, – a preferred method cannot be defined, – the choice of the analytical method should include analytical questions (the sample matrix, the occurrence of other disturbing radionuclides, the necessary detection limit) and economical questions (costs, other parameters to be determined).
Spectroscopic investigation of humic substances in a tropical lake during a complete hydrological cycle
Authors: Oliveira Janaìna L. , Boroski Marcela , Azevedo Jùlio C. R. , Nozaki Jorge 
Published: January 2007

AbstractFluorescence and UV‐VIS techniques were employed for the investigation of natural organic matter (NOM) of a tropical lake. The relationships of absorbance/dissolved organic carbon (A/DOC), fluorescence intensity/dissolved organic carbon (FI/DOC), fluorescence ratio (FR), and peak wavelength with the highest intensity (PW) were used to distinguish the pedogenic or aquagenic origin of NOM. The values of FR, PW and A285/DOC of high waters (HW) or flooded period samples and of low waters (LW) period samples of the dry season, except for September 2002, confirm the predominance of pedogenic material. The spectra of water were similar to the standard fulvic acid (FA), and the spectra of FA from the lake were similar to the nearby soils, indicative of pedogenic predominance. The results confirm that the dissolved NOM of Patos Lagoon – MS (Brazil), in all sampling periods, predominantly consisted of humic substances (FA) of pedogenic origin.
Infanticide and cannibalism in a free‐ranging plurally breeding group of common marmosets (Callithrix Jacchus)
Authors: Bezerra Bruna Martins , Souto Antonio Da Silva , Schiel Nicola 
Published: January 2007

AbstractOur study presents a detailed description of infanticide and cannibalism in a free‐ranging plurally breeding group of Callithrix jacchus. The 1‐month‐old infant was the daughter of the dominant female, and was attacked by the group's second breeding female. Two months later, the latter gave birth to twins and appeared to have become the dominant female. These findings confirm and extend previous reports of infanticide by pregnant female marmosets, and indicate that infants of dominant breeding female, as well as those of subordinate females, are vulnerable to infanticide in plurally breeding groups. With respect to the cannibalism, this act seemed to be mainly a response to the prompt availability of food, represented by the killed infant. Am. J. Primatol. 69:945–952, 2007. © 2007 Wiley‐Liss, Inc.
Ground use by northern muriquis (Brachyteles hypoxanthus)
Authors: Mourthé Ítalo M.C. , Guedes Danusa , Fidelis Janaína , Boubli Jean P. , Mendes Sérgio L. , Strier Karen B. 
Published: January 2007

AbstractMany arboreal primates descend to the ground, a custom that may occur more frequently in disturbed habitats, and in the presence of researchers to whom the primates are habituated. In this paper, we describe opportunistic observations of ground use in two groups of northern muriquis (Brachyteles hypoxanthus) at the RPPN Feliciano Miguel Abdala, Minas Gerais, Brazil. Members of both groups were observed drinking, resting, feeding, playing, and traveling on the ground to different degrees, and variation in the levels of habituation of the two groups may be responsible for the differences in the distribution of their terrestrial activities. The potential increase in vulnerability to predation or disease owing to ground use has implications for the conservation of this critically endangered species. Am. J. Primatol. 69:706–712, 2007. © 2007 Wiley‐Liss, Inc.
C‐C‐Kupplungen mit Alkoholen als Elektrophilen: der Wasserstoff‐Autotransfer
Authors: Guillena Gabriela , Ramón Diego J. , Yus Miguel 
Published: January 2007

AbstractDer Wasserstoff‐Autotransfer ist eine neue Art von Dominoreaktion. Die Sequenz umfasst eine einleitende oxidative Wasserstoffeliminierung, eine nachfolgende C‐C‐Kupplung verschiedenen Typs und zum Abschluss eine reduktive Wasserstoffanlagerung zur Bildung des Endprodukts. Mithilfe des Wasserstoff‐Autotransfers gelingt die Alkylierung nukleophiler Substrate mit Alkoholen als Elektrophilen unter milden Reaktionsbedingungen (schwache Basen, niedrige Temperaturen) und mit Wasser als dem einzigen Beiprodukt. Durch die Einführung verschiedener metallorganischer Katalysatoren konnte der Substratbereich deutlich erweitert werden. Dieser Kurzaufsatz fasst die neusten Fortschritte zusammen.
Alcohols as Electrophiles in CC Bond‐Forming Reactions: The Hydrogen Autotransfer Process
Authors: Guillena Gabriela , Ramón Diego J. , Yus Miguel 
Published: January 2007

AbstractThe hydrogen autotransfer process involves an initial oxidative hydrogen elimination, followed by different types of reactions, and is completed with a reductive hydrogen addition to give the final product. The sequence allows the alkylation of different nucleophilic agents using environmentally benign alcohols as electrophiles, mild conditions, and soft bases, with water produced as the only waste material. Recent examples of modulating the organometallic catalyst have also lent themselves to expansion of the range of available substrates, as described in this Minireview.
Degree of conversion versus the depth of polymerization of an organically modified ceramic dental restoration composite by fourier transform infrared spectroscopy
Authors: Silva Fabio F. , Mendes Luis C. , Ferreira Marysilvia , Benzi Marcia R. 
Published: January 2007

AbstractThe evaluation of the degree of conversion (DC) as a function of the depth (1–4 mm) of an organically modified ceramic (ormocer) dental restoration composite activated by a conventional light‐curing unit (450 nm, 21.2 J/cm2) was carried out. Fourier transform infrared spectroscopy was employed to measure DC at each depth with the ratio of the maximum height absorbance peaks at 1638 (variable band) and 1609 cm−1 (reference band) before and after the polymerization reaction. The formulation was reconstituted to understand better the composite behavior. The organic and inorganic fractions were characterized by thermogravimetric analysis, X‐ray fluorescence, proton nuclear magnetic resonance, and scanning electron microscopy. The DC values lay between 48 and 54%, seemed to be not sensitive to the depth of polymerization, and indicated a large amount of residual monomer. On the other hand, a continuous decrease in the Vickers microhardness (from 61 to 52) was observed with an increasing depth of polymerization. This behavior could be attributed to differences in the crosslinking degree on the top and bottom surfaces of the polymerized samples. The material was a conventional dental restoration composite containing 26% monomer mixture (bisphenol A/dimethacrylate and triethylene glycol dimethacrylate), a small amount (2%) of an ormocer as a compatibilizing agent, and 72% inorganic filler (barium sulfate and aluminum silicate). The low DC values could be ascribed to several factors, such as the monomer viscosities, amounts, and types, the average sizes and distributions of the fillers, and the large difference between the refractive indices of the organic and inorganic constituents. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 325–330, 2007
Thermal, mechanical, and adhesive properties of HDPE/reactive ethylene terpolymer blends
Authors: Love C. T. , Xian G. , Karbhari V. M. 
Published: January 2007

AbstractBlends of high‐density polyethylene (HDPE) and a reactive ethylene terpolymer (RET) were developed as a protective coating material for steel. A morphological study with scanning electron microscopy (SEM) indicated that blends of HDPE and RET are immiscible, while high interaction between these two phases was found. Crystallization and thermomechanical behavior of the blends were investigated using differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). The crystallinity of HDPE decreased with the incorporation of RET slightly due to the disturbance of the highly viscous RET melt during crystallization. Tensile tests indicated that the addition of RET reduced both strength and modulus but increased the strain‐to‐break. Adhesion to steel substrates was improved with the incorporation of the RET component. An optimum composition of RET loading was detected to be in the range of 25–33 wt %, leading to the best adhesive performance, high tensile strength, and strain‐to‐failure of the blend material. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 331–338, 2007
The transient nature of maximum maleic anhydride grafting of polypropylene: A mechanistic approach based on a consecutive reaction model. II. A comparison of the batch solution and molten state processes
Authors: García‐Martínez J. Ma. , Areso S. , Collar E. P. 
Published: January 2007

AbstractThis article compares the batch solution and molten state chemical modification of an atactic polypropylene to yield a grafted polypropylene. Short reaction times appear to be sufficient and indeed necessary for the highest graft yields to be obtained if degradative processes occurring in both reaction media are to be avoided. The consecutive reactions for the optimized grafting reaction pathway were proposed for the solution process in an earlier article. The present work attempts to correlate this pathway with that of the molten state process. Grafted succinic anhydride groups react with two resorcine molecules to yield grafted succinyl‐fluorescein groups. This work considers the resorcine units as true molecular probes, to be able to stabilize and activate the complexes formed between the succinic anhydride groups and the propylene sequence. This work shows the unsteady and later dynamic character of the process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 345–351, 2007
Rheological properties of poly(methyl methacrylate)/rigid ladderlike polyphenylsilsesquioxane blends
Authors: Li Guizhi , Matsuda T. , Nishioka A. , Liang Kaiwen , Masubuchi Y. , Koyama K. , Pittman Charles U. 
Published: January 2007

AbstractA series of poly(methyl methacrylate) (PMMA) blends with rigid ladderlike polyphenylsilsesquioxane (PPSQ) were prepared at weight ratios of 100/0, 95/5, 90/10, 85/15, and 80/20 by solution casting and then hot‐pressing. Their rheological properties have been studied under both dynamic shear and uniaxial elongation conditions. Their rheological properties depend on the compositions. The storage modulus, G′, loss modulus, G″, and dynamic shear viscosity, η*, of the PMMA/PPSQ 95/5 blend were slightly lower than those of pure PMMA. However, the values of G′, G″, and η* for the other PMMA/PPSQ blends are higher than those of PMMA. The G′ values increase with an increase in PPSQ content from 5% through 15% PPSQ at low frequencies and then drop as the PPSQ content increases to 20%. Uniaxial elongational viscosity (ηE) data demonstrate that PMMA/PPSQ blends exhibit slightly weaker (5% PPSQ) and much weaker (10% PPSQ) strain‐hardening than PMMA. In contrast, the PMMA/PPSQ 85/15 blend shows strain‐softening. Neither strain‐hardening nor strain‐softening was observed in the 80/20 blend. The special rheological properties for the 95/5 blend is probably due to a decrease in PMMA entanglements brought by the specific PMMA–PPSQ interactions. Rheological properties of PMMA/PPSQ blends with higher PPSQ content (≥10%) are mainly affected by formation of hard PPSQ particles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 352–359, 2007
Polymer blends of carboxylated butadiene‐acrylonitrile copolymer (nitrile rubber) and polyamide 6 developed in twin screw extrusion
Authors: Chowdhury Rajesh , Banerji M. S. , Shivakumar K. 
Published: January 2007

AbstractPolymer blends of carboxylated butadiene‐acrylonitrile copolymer (nitrile rubber) and polyamide 6 (PA6) were developed in twin screw extrusion. The rubber was cured with SP 1045 methylol phenolic resin during melt mixing in twin screw. Effect of degree of carboxylation in the rubber phase on blend properties has been assessed. Phase morphologies have been characterized using transmission electron microscopy. A compatibilizing NBR‐g‐Nylon 6 graft copolymer generated in situ during melt mixing via interfacial reaction between the COOH groups in NBR and the NH2 end groups in nylon 6 has been effective in generating a fine and stable dispersion of the rubber within the polyamide matrix. The graft copolymer has been characterized by DMTA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 372–377, 2007
Investigations on the adhesion and interfacial properties of polyurethane foam/thermoplastic materials
Authors: Mahmood Nasir , Busse Karsten , Kressler Jörg 
Published: January 2007

AbstractThe adhesion and interfacial properties of polyurethane (PU) foams with thermoplastic (TP) materials were investigated using different techniques. The adhesion performance of PU foam with TP materials was evaluated using the peel test method, and the adhesion durability was checked after different climate treatments. X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and contact angle measurements were used to study the surface and interface morphology of PU foam and TP material system. Three types of PU foam samples which differ in their composition and also five commercially available TP blends systems, based on poly(carbonate), poly(styrene‐co‐maleic anhydride), poly(acrylonitrile‐butadiene‐styrene), and silicone acrylate rubber have been used. The slow reacting foam shows the best adhesion properties with all the TP materials. The climate treatments strongly effected the PU foam adhesion durability with poly(carbonate) containing TP materials (70–80% loss in adhesion), but nearly no effect with poly(styrene‐co‐maleic anhydride). The samples with lowered adhesion could be separated by peeling without visible foam residues on the TP surface. AFM, XPS, and surface tension studies have shown that the surface properties of the TP material are still governed by the PU foam. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 479–488, 2007
Preparation of Ag nanoparticles in the presence of low generational poly(ester‐amine) dendrimers
Authors: Xu Dong‐Mei , Zhang Ke‐Da , Zhu Xiu‐Lin 
Published: January 2007

AbstractStable Ag nanoparticles of 10–20 nm were prepared by reduction of AgNO3 with NaBH4 in water solution in the presence of low generational hydroxyl‐ terminated poly(ester‐amine) dendrimer G1.0 (OH)16 and amino‐terminated poly(ester‐amine) dendrimer G1.5 (NH2)8 by optimizing preparation conditions. UV–vis absorption spectra and transmission electron microscopy were adopted to characterize absorption properties of Ag+/dendrimer complex, Ag/dendrimer nanocomposite aqueous solutions, and the morphology of the formed Ag nanoparticles, respectively. The results showed that the size of the Ag particles increased with Ag+/dendrimer molar ratio, and the size of Ag nanoparticles in Ag/G1.0 (OH)16 system was larger than that of Ag nanoparticles in Ag/G1.5 (NH2)8 system, while the polydispersities of two systems were similar. Moreover, the Ag/G1.5 (NH2)8 nanocomposite system was more stable than the Ag/G1.0 (OH)16 one. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 422–426, 2007