bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of fullerene encapsulation in carbon nanotubes using a complex approach based on vibrational spectroscopy
Authors: Botos Ákos , Khlobystov Andrei N. , Botka Bea , Hackl Rudi , Székely Edit , Simándi Béla , Kamarás Katalin 
Published: September 2010

AbstractFor carbon nanotubes filled with fullerenes (“peapods”), it is a key issue to find an analytical method that distinguishes the molecules inside the nanotube from those adsorbed on its surface. High‐resolution transmission electron microscopy (HRTEM) detects both encapsulated and adsorbed molecules which are large enough (e.g., fullerenes), but being a local‐probe method, it cannot be applied to large amounts of sample. In Raman spectroscopy, the empirical rules for line shifts and splitting are nanotube‐type dependent and often ambiguous. We prepared C60 peapods by nano‐extraction using supercritical CO2 as a solvent, and subsequently removed the adsorbed fullerene molecules by washing the samples. We analyzed the samples by the combination of HRTEM, Raman, and midinfrared attenuated total reflectance (MIR‐ATR) spectroscopy. Although the TEM images proved that the nanotubes were filled with fullerenes, we did not observe any shift in the fullerene's Ag(2) Raman mode compared to C60 crystals. ATR spectra, on the other hand, were found to detect only the adsorbed molecules. Therefore, the combination of the two methods provide good basis for determining the success of nanotube filling by spectroscopy alone.
Electronic and morphological properties of the electrochemically prepared step bunched silicon (111) surface
Authors: Skorupska K. , Pettenkofer Ch. , Sadewasser S. , Streicher F. , Haiss W. , Lewerenz H. J. 
Published: September 2010

AbstractTopographical and electronic and properties of step bunched Si(111), prepared by electrochemical processing in alkaline solution, are analyzed. Tapping mode atomic force microscopy (TM AFM) analysis shows that one bunched step consists of about 15 atomic steps (each 0.314 nm in height) and that the (111) oriented terraces have widths that range from 150 to 250 nm. Scanning tunneling microscopy (STM) experiments show a corrugation of the (111) terraces with an rms roughness of 0.5–0.8 nm, correlated with etch pits in alkaline solution. Low energy electron diffraction (LEED) data show a splitting of the (10) and (01) spot from which a minimum terrace width of 4.8 nm have been calculated in good agreement with the TM AFM data. Kelvin probe force microscopy (KPFM) experiments show a decrease of the contact potential difference (CPD) at and near the edges of steps indicating a more negatively charged surface area. Synchrotron radiation photoelectron spectroscopy (SRPES) on electrochemically and purely chemically prepared step bunched surfaces is compared. From the Si 2p core level shift, and, in particular, from the onset of the valence band emission, an accumulation layer‐type shift is observed on the electrochemically prepared sample that is absent for chemical preparation. The move of the Fermi level toward the conduction band minimum of the electrochemically conditioned samples is interpreted by H incorporation and discussed by a doping model that involves the mechanism of hydrogen evolution.
Band offsets of polar and nonpolar GaN/ZnO heterostructures determined by synchrotron radiation photoemission spectroscopy
Authors: Liu J. W. , Kobayashi A. , Toyoda S. , Kamada H. , Kikuchi A. , Ohta J. , Fujioka H. , Kumigashira H. , Oshima M. 
Published: September 2010

AbstractC‐plane (polar) and m‐plane (nonpolar) GaN/ZnO heterostructures have been fabricated by pulsed laser deposition at room temperature, and their electronic structures have been characterized by synchrotron radiation photoemission spectroscopy. Based on the binding energies of core levels and valence band maximum values, the valence band offsets have been found to be 0.7 ± 0.1 and 0.9 ± 0.1 eV for polar and nonpolar GaN/ZnO heterojunctions, respectively. Both heterostructures show type‐II band configurations with conduction band offsets of 0.8 ± 0.1 and 1.0 ± 0.1 eV, respectively. GaN and ZnO show upward and downward band bending toward the interface in the nonpolar GaN/ZnO heterojunction. However, both GaN and ZnO show upward band bending toward the interface in the polar heterojunction, which is attributed to negative charges. Analysis of N 1s spectra has revealed that N–O bonds exist only at the polar interface, which probably caused the formation of the negative charges.
Negative stiffness of a buckled carbon nanotube in composite systems via molecular dynamics simulation
Authors: Wang Yun‐Che , Wu Chun‐Yi , Kuo Qu‐Yuan 
Published: September 2010

AbstractDue to structural effects, mechanically buckled tubes may exhibit negative stiffness (NS). The NS composites, formed by embedding the NS and positive‐stiffness (PS) phases, have been shown to exhibit exceptional enhancements in their effective stiffness and viscoelastic damping. Through molecular dynamics simulation with the first‐generation Tersoff–Brenner interatomic potential, we studied the composite system of the buckled (5,5) carbon nanotube (CNT), negative stiffness provider, being compressed laterally with a carbon fullerene (Cx) for x = 20, 60, 100, and 540. It was found the CNT‐Cx system showed about 10 N/m for its spring constant in the linear range. When x = 20, 60, and 100, after reaching maximum loading, applied total force vs. lateral compression showed plateau‐type behavior due to a series of local buckling, indicating it is a low‐energy cost process to revert a buckled nanotube to an unbuckled state with the creation of local buckling. When x = 540, hardening‐type force–displacement relationship was observed due to the interplay between the NS and PS phases. For all of the four cases, the effective stiffness along the loading direction was negative for large lateral compression since the buckled CNT provided more negative stiffness than the positive stiffness in the fullerene.
Structure of influenza virus ribonucleoprotein complexes and their packaging into virions
Authors: Noda Takeshi , Kawaoka Yoshihiro 
Published: September 2010

AbstractThe influenza A virus genome consists of eight segmented, single‐stranded, negative‐sense RNAs. Each viral RNA (vRNA) segment forms a ribonucleoprotein (RNP) complex together with NPs and a polymerase complex, which is a fundamental unit for transcription and replication of the viral genome. Although the exact structure of the intact RNP remains poorly understood, recent electron microscopic studies have revealed certain structural characteristics of the RNP. This review focuses on the findings of these various electron microscopic analyses of RNPs extracted from virions and RNPs inside virions. Based on the morphological and structural observations, we present the architecture of RNPs within a virion and discuss the genome packaging mechanism by which the vRNA segments are incorporated into virions. Copyright © 2010 John Wiley & Sons, Ltd.
Tribo‐electrochemical surface modification of tantalum using in situ AFM techniques
Authors: Huitink David , Gao Feng , Liang Hong 
Published: September 2010

AbstractA scanning‐probe‐based technique to observe tribo‐electrochemically stimulated surface was demonstrated. The configuration consists of an electrochemical cell attached to an atomic force microscope (AFM) scanner. Under an applied electrical potential and in various chemical environments, the surface morphology, roughness, skew, bearing ratio, as well as surface adhesive forces between probes were measured, and the effects of mechano‐electrochemical stimuli were evaluated. The effects of mechanical, electrochemical, and mechano‐electrochemical stimuli were found to compete during AFM sliding process. Their effects do not follow a linear relationship, implying that the mechanical stimulus promotes electrochemical reactions. Similarly, electrochemically enhanced mechanical removal of surface materials is possible. SCANNING 32: 336–344, 2010. © 2010 Wiley Periodicals, Inc.
Laser profilometry and length‐scale analysis of stone tools: second series experiment results
Authors: James Stemp W. , Childs Ben E. , Vionnet Samuel 
Published: September 2010

AbstractBased on the need to develop a method to reliably and objectively document and discriminate the use‐wear on archaeological stone tools, Stemp et al. (2009) tested whether the surface roughness measured on experimentally worn stone tools used on different contact materials could be discriminated. Results of these initial experiments indicated that discrimination was possible and also determined the scales over which this discrimination occurred. In this article, we report the results of additional experiments using the same method on a second set of tools to test its reliability and reproducibility. In these experiments, four flint flakes were intensively used for 20 min on either conch shell or dry deer antler. The surface roughness or texture of the stone tools was measured by generating 2D profiles using a UBM laser profilometer. Relative lengths (RLs) calculated from the profiles were used directly as characterization parameters and subsequently compared statistically at each scale using the F‐test to establish a level of confidence for the differentiation at each scale represented in the measured profiles. The mean square ratios of measurement data were used to determine whether the variation in roughness was statistically significant and to what level of confidence. The scales at which there was a high level of confidence were the ones at which the tools were differentiable. The results of these experiments confirm our previous findings that RLs, over certain scale ranges, can discriminate the stone tool surface wear profiles produced by the different contact materials. SCANNING 32: 233–243, 2010. © 2010 Wiley Periodicals, Inc.
Nanoscale crystallization of phase change Ge2Sb2Te5 film with AFM lithography
Authors: Kim JunHo 
Published: September 2010

AbstractWe have made nanoindents on Ge2Sb2Te5 (GST) films using electric field‐assisted atomic force microscope (AFM) lithography. GST shows increase of material density and electric conductivity as it changes from amorphous to crystalline phases. By applying electric field between AFM probe‐tip and GST surface, nanoscale crystallization could be induced on tip contact area. As the crystallized GST exhibits increase of material density, that is to say depression of volume, nanoindented surface with crystallization is created on host amorphous GST (a‐GST) film. For the AFM lithography, a highly conductive tip, which showed voltage‐switching characteristics in current–voltage spectroscopy of GST film, was found to be very suitable for recording and sensing crystallized nanoindents on the GST film. By varying sample bias voltages, we performed nanoscale crystallization, and measured the nanostructured film in AFM conductance‐image (C‐image) mode and topography‐image (T‐image) mode, simultaneously. Two types of crystallized wires were fabricated on (a‐GST) film. Type‐I was sensed in only C‐image, whereas Type‐II was sensed in both C‐image and T‐image. These nanowires are discussed in terms of crystallization of GST and sensitivity of current (or topography) sensing. By repeated lithography, larger size of nanoindented wires were also produced, which indicates line‐dimension controllability of AFM lithography. SCANNING 32: 320–326, 2010. © 2010 Wiley Periodicals, Inc.
A Temperature‐Responsive Nanoreactor
Authors: Li Songjun , Ge Yi , Tiwari Ashutosh , Cao Shunsheng 
Published: September 2010

AbstractAn originally designed temperature‐responsive nanoreactor is reported. The nanoreactor is made of Ag nanoparticles and a functional polymer composite of poly(acrylamide) (PAAm) and poly(2‐acrylamide‐2‐methylpropanesulfonic acid) (PAMPS). At a relatively low temperature (e.g., 20 °C), this nanoreactor displayed weak reactivity because of the interpolymer complexation between PAAm and PAMPS, which largely restricted the access of reactants to the encapsulated Ag nanoparticles. On the contrary, at a relatively high temperatures (e.g., 40 °C), the nanoreactor demonstrated significant catalytic activity resulting from the dissociation of the interpolymer complexation between PAAm and PAMPS, which allowed reactants to get access to the encapsulated Ag nanoparticles. By taking account of previously reported PNIPAm‐based nanoreactors, which show inverse temperature response, i.e., reactivity decreases whilst temperature increases, this temperature‐responsive nanoreactor would greatly facilitate and enrich the increasing studies on smart nanomaterials, generating numerous applications in a wide range of areas, such as catalysis and sensing.
Splines, knots, and penalties
Authors: Eilers Paul H. C. , Marx Brian D. 
Published: September 2010

AbstractPenalized splines have gained much popularity as a flexible tool for smoothing and semi‐parametric models. Two approaches have been advocated: (1) use a B‐spline basis, equally spaced knots, and difference penalties [Eilers PHC, Marx BD. Flexible smoothing using B‐splines and penalized likelihood (with Comments and Rejoinder). Stat Sci 1996, 11:89–121.] and (2) use truncated power functions, knots based on quantiles of the independent variable and a ridge penalty [Ruppert D, Wand MP, Carroll RJ. Semiparametric Regression. New York: Cambridge University Press; 2003]. We compare the two approaches on many aspects: numerical stability, quality of the fit, interpolation/extrapolation, derivative estimation, visual presentation and extension to multidimensional smoothing. We discuss mixed model and Bayesian parallels to penalized regression. We conclude that B‐splines with difference penalties are clearly to be preferred.WIREs Comp Stat2010 2 637–653 DOI: 10.1002/wics.125This article is categorized under:Statistical and Graphical Methods of Data Analysis > Density Estimation
The effectiveness of indigestible markers for identifying individual animal feces and their prevalence of use in North American zoos
Authors: Fuller Grace , Margulis Susan W. , Santymire Rachel 
Published: September 2010

AbstractTechniques for analyzing hormone metabolites in animal excreta have created many opportunities for noninvasive monitoring of health, reproduction, and welfare in zoo animals, but can be difficult to implement when individual samples are not readily identifiable in animal groups. A common approach to this problem is to feed animals an indigestible marker that subsequently appears in feces, but there has been little systematic research on the use of such “fecal markers.” First, we used an online survey to assess the prevalence of fecal marker use in North American zoological institutions. Second, we conducted a series of experimental tests utilizing commonly employed fecal markers in a variety of typical zoo taxa to determine the: (1) effectiveness of several markers to accurately distinguish samples in a variety of species, (2) minimum quantity of marker needed for detection, and (3) length of time between ingestion and detection in the feces. The majority of the 45 institutions that completed the survey reported using fecal markers with their collections. The survey also revealed that the most frequently used markers are seeds/grains and food colorants, with the former generally used in Carnivora and the latter in Primates. Our experimental data confirmed the success of these taxa/marker combinations and also revealed that food colorants function as markers in a variety of avian, reptilian, and mammalian species. Our data describe successful fecal markers for a wide variety of zoo taxa and should, therefore, be useful for zoological managers and researchers needing to employ fecal markers in future investigations. Zoo Biol 30:379–398, 2011. © 2010 Wiley‐Liss, Inc.
Genetic structure analysis of a highly inbred captive population of the African antelope Addax nasomaculatus. Conservation and management implications
Authors: Armstrong E. , Leizagoyen C. , Martínez A.M. , González S. , Delgado J.V. , Postiglioni A. 
Published: September 2010

AbstractThe African antelope Addax nasomaculatus is a rare mammal at high risk of extinction, with no more than 300 individuals in the wild and 1,700 captive animals distributed in zoos around the world. In this work, we combine genetic data and genealogical information to assess the structure and genetic diversity of a captive population located at Parque Lecocq Zoo (N=27), originated from only two founders. We amplified 39 microsatellites previously described in other Artiodactyls but new to this species. Seventeen markers were polymorphic, with 2–4 alleles per locus (mean=2.71). Mean expected heterozygosity (He) per locus was between 0.050 (marker ETH3) and 0.650 (marker D5S2), with a global He of 0.43. The mean inbreeding coefficient of the population computed from pedigree records of all registered individuals (N=53) was 0.222. The mean coancestry of the population was 0.298 and FIS index was −0.108. These results reflect the importance of an adequate breeding management on a severely bottlenecked captive population, which would benefit by the incorporation of unrelated individuals. Thanks to the successful amplification of a large number of microsatellites commonly used in domestic bovids, this study will provide useful information for the management of this population and serve as future reference for similar studies in other captive populations of this species. Zoo Biol 30:399–411, 2011. © 2010 Wiley‐Liss, Inc.
RetractedFood habits of Rhinopithecus bieti as assessed by fecal analysis at Mt. Longma, Southwest China
Authors: Li Xue‐You , Yang Shi‐Jian , Yang Yang 
Published: September 2010

AbstractThe following article from Zoo Biology, "Food habits of Rhinopithecus bieti as assessed by fecal analysis at Mt. Longma, Southwest China" by Xue‐You Li, Shi‐Jian Yang and Yang Yang, published online on September 17, 2010, in Wiley Online Library (http://onlinelibrary.wiley.com), has been retracted by agreement between the authors, the journal's Executive Editor, Jason V. Watters, and the publisher, Wiley Periodicals, Inc. The retraction has been agreed due to overlap between this article and the following article published in the American Journal of Primatology: "Diet and feeding behavior of Rhinopithecus bieti at Xiaochangdu, Tibet: adaptations to a marginal environment" by Zuo‐fu Xiang, Sheng Huo, Wen Xiao, Rui‐chang Quan and Cyril C. Grueter. Am J Primatol 69:1141–1158, 2007.
S‐adenosylhomocysteine hydrolase deficiency: two siblings with fetal hydrops and fatal outcomes
Authors: Grubbs Randall , Vugrek Oliver , Deisch Jeremy , Wagner Conrad , Stabler Sally , Allen Robert , Barić Ivo , Rados Marko , Mudd S. Harvey 
Published: September 2010

AbstractThis paper reports the clinical and metabolic findings in two sibling sisters born with fetal hydrops and eventually found to have deficient S‐adenosylhomocysteine hydrolase (AHCY) activity due to compound heterozygosity for two novel mutations, c.145C>T; p.Arg49Cys and c.257A>G; p.Asp86Gly. Clinically, the major abnormalities in addition to fetal hydrops (very likely due to impaired synthetic liver function) were severe hypotonia/myopathy, feeding problems, and respiratory failure. Metabolic abnormalities included elevated plasma S‐adenosylhomocysteine, S‐adenosylmethionine, and methionine, with hypoalbuminemia, coagulopathies, and serum transaminase elevation. The older sister died at age 25 days, but the definitive diagnosis was made only retrospectively. The underlying genetic abnormality was diagnosed in the second sister, but treatment by means of dietary methionine restriction and supplementation with phosphatidylcholine and creatine did not prevent her death at age 122 days. These cases extend the experience with AHCY deficiency in humans, based until now on only the four patients previously identified, and suggest that the deficiency in question may be a cause of fetal hydrops and developmental abnormalities of the brain.
Plant diversity and dry‐matter dynamics of peri‐urban plant communities in an Indian dry tropical region
Authors: Gupta Shachi , Narayan Rup 
Published: September 2010

AbstractThe emergence of variety of land‐use changes due to continuous anthropogenic pressure in peri‐urban areas may concomitantly result in modification of the structure of associated plant communities for their sustainable growth. In the present study, plant diversity, and above‐ and belowground biomass distribution among species were investigated to understand their dynamics across different season, soil, and site conditions in a dry tropical peri‐urban region in India. From four study sites that covered contrasting land uses: abandoned brick kiln (ABK), grazing land (GL), Kali river bank (KRB), and agricultural land (AL), a total of 360 monoliths were randomly extracted in three seasons, and dry weights were estimated for aboveground and belowground parts of species individuals. Seasonal soil samples of the sites were analyzed for physico‐chemical characteristics. Of the total 87 recorded species that were mainly annual weeds and ruderals, 77% were forbs and 23% grasses. The ranges of plant biomass recorded across all sites and seasons were: aboveground 228–738 g m−2, belowground 83–288 g m−2, and a total of 344–1,026 g m−2. The dominance of species differed between above‐ and belowground; some species dominated only above‐ or belowground, and others dominated in both layers. Above‐ and belowground biomass of the sites, differential community‐biomass allocation to above‐ and belowground parts and species dominants varied significantly with site and season. ABK and AL sites showed lower species diversity and soil nutrients compared to GL and KRB sites. Belowground biomass significantly declined with increasing soil organic C and total N, indicating altered dry matter allocation under resource‐scarce habitat conditions. Higher diversity occurred at both low‐ and high‐biomass sites, reflective of enhanced ability of these plant communities to exploit resources maximally in spatio‐temporal pattern.
Determination of Acid Number of Biodiesel and Biodiesel Blends
Authors: Baig Aijaz , Ng Flora T. T. 
Published: September 2010

AbstractDue to an increase in the commercial use of biodiesel and biodiesel blends, both ASTM D 6751 and EN 14214 include the acid number (AN) as an important quality parameter. It was found that determination of AN of biodiesel and biodiesel blends using the ASTM D 974 results in large values of repeatability (up to 73.41%) and larger percentage error (up to 42.88%). Therefore, ASTM D 974 has been modified using a lower concentration of base (0.02 M KOH instead of 0.1 M KOH) as well as reducing the amount of toxic titration solvent from 100 mL to only 10 mL. This makes the modified ASTM D 974 as a green analytical method which uses a reduced amount of toxic solvent. This modified method significantly reduced the maximum percentage error from 42.88 to 5.92%. The application of this modified ASTM D 974 for the determination of AN of biodiesel and biodiesel blends was studied. The accuracy of this modified ASTM D 974 for biodiesel (B100) was measured to be within 3.51% over the AN range of 0.313–0.525 mg KOH/g and maximum repeatability was decreased from 8.37 to 2.75% within this AN range which is far below the ASTM D 974 stated repeatability specifications. For B20, B10, B5, B2, and B1, the most accurate values were measured at AN values of 0.177, 0.067, 0.072, 0.126, and 0.096 mg KOH/g, respectively. Excellent linearity values of R2 for calculated and experimentally determined AN were obtained. The difference between the experimental and the calculated AN for all biodiesel and biodiesel blend samples was within ± 0.018 mg KOH/g. This extensive study has demonstrated that this modified ASTM D 974 is a reliable method for the determination of AN and could be used for establishing the specifications of AN for biodiesel and biodiesel blends ranging from B1 to B20 in quality standards.