bluuebunny/crossref_metadata_2025_split huggingface dataset:
Field Flow Fractionation in Analysis of Polymers and Rubbers
Authors: Ratanathanawongs Williams S. Kim , Benincasa Maria‐Anna , Ashames Akram A. 
Published: December 2009

AbstractField‐flow fractionation (FFF) was conceived by Calvin Giddings in 1966 as a separation and characterization method for macromolecules, colloids, and particulates. Like chromatography, sample migration is caused by differential interaction with a field acting along an axis orthogonal to that of the transport liquid. Unlike chromatography, where separation is achieved by solutes partitioning between mobile and stationary phases, separation in FFF arises from the distribution of sample components in fluid laminae flowing at different velocities in a single phase. The different flow velocities, described by a parabolic profile, arise from the high aspect ratio of the FFF channel. Different types of fields can be used in FFF as long as they interact with some physicochemical property of the sample. The FFF channel design makes it highly suited for analyses of fragile aggregates, high‐molecular‐weight polymers, and gels. In comparison with packed columns, shear rates in the channel and the probability of plugging the channel are low. The ability of thermal FFF to differentiate polymers and latexes of different bulk and surface compositions is unique among currently used separation techniques. The FFF family of techniques can provide a great deal of information about the sample but an initial time investment is often required for methods development.In this article, the fundamental mechanism of FFF is shown at play in the separation and characterization of polymers and rubbers by the two techniques par excellence in this field: flow FFF and thermal FFF.
Probing Biomolecular Interactions Using Nanopore Force Spectroscopy
Authors: Dudko Olga K. , Meller Amit 
Published: December 2009

Abstract
The ability to apply a force on individual biomolecular complexes and measure their time‐dependent response have begun to reveal their mechanical properties, interactions with other biomolecules, and self‐interactions. A number of single‐molecule methods have been developed and applied in the past decade to broad range of biological system, including proteins in the skeletal and cardiac muscle sarcomere, nucleic acid complexes, and enzymes. Nanopore force spectroscopy (NFS) is an emerging single‐molecule method that takes advantage of the native electrical charge of biomolecule to exert a localized bond‐rupture force. This article reviews the basic principles of the method and discusses two bond‐breakage modes utilizing either a constant voltage or a fixed voltage ramp, which are related quantitatively in an essentially model‐free way. A unified theoretical formalism is developed to extract kinetic information from the NFS data. The utility of this formalism is illustrated by analyzing data from nanopore unzipping of individual DNA hairpin molecules.
Spin Probes and Spin Labels
Authors: Smirnova Tatyana I. , Voinov Maxim A. , Smirnov Alex I. 
Published: December 2009

AbstractElectron paramagnetic resonance (EPR) spectroscopy is a versatile and exceptionally sensitive technique for detecting and studying molecular systems possessing unpaired electronic spins. It finds substantial use in characterizing paramagnetic metal ions and organic free radicals. The scope of EPR applications in analytical chemistry can be expanded significantly by means of spin labels and spin probes — exogenous EPR‐active species that are introduced solely for the purpose of gaining information on the system under study. These labels and probes are persistent free radicals or paramagnetic metal ions designed to be partitioned or attached to specific molecular sites. To be suitable for analytical applications, spin labels and probes should readily report on properties of interest, exhibit distinguishable from background EPR signals, and leave the system only minimally perturbed by their presence. In this article, we describe a series of spin labels and probes as well as the associated EPR methods that are tailored to specific analytical applications of EPR spectroscopy — from assessing local oxygen and proton concentration to profiling electrostatic properties of biopolymers and lipid bilayers. The primary focus is bioanalytical applications of spin label/probe methods, with an emphasis on the synergy between the rational design of spin‐bearing molecules using the tools of organic chemistry and desired analytical capabilities.
Neutron Resonance Capture and Transmission Analysis
Authors: Postma Hans , Schillebeeckx Peter 
Published: December 2009

AbstractNeutrons can be used as probes to investigate and study properties of materials and objects. The deep penetration of neutrons into matter allows the study of bulk properties. One evolving activity in this field concerns the existence of resonances in neutron‐induced reaction cross sections in the neutron energy range from thermal up to a few megaelectronvolts for certain nuclides. Since these resonances appear at neutron energies, which are specific for each nuclide, they are very suitable for the determination of the elemental composition of objects and materials. Neutron resonance capture analysis (NRCA) and neutron resonance transmission analysis (NRTA) are two methods used for exploiting the resonance structure in the neutron‐induced reaction cross sections. Both methods are nondestructive, determine the bulk elemental composition, do not require any sample preparation, and result in a negligible residual activity. NRCA is applicable to almost all stable elements, while NRTA is preferred for light elements or nuclei near a closed shell. Quantitative NRCA and NRTA have been used for the analysis of archeological objects and reference materials used for cross‐section measurements. Other applications of neutron resonance spectroscopy range from radiography of nuclear fuel (including spent fuel), detection of explosives and drugs, to thermometry and diamond mining.
Preanalytical Variation in Clinical Laboratory Testing
Authors: Setia Namrata , Nichols James H. 
Published: December 2009

AbstractLaboratory testing can be divided into preanalytic, analytic, and postanalytic phases. Medical errors are most frequent in the preanalytic phase of testing. Preanalytic variables can affect test results, leading to misinterpretation and inappropriate patient care. Physicians should be educated on the potential for preanalytic variation and to question test results for potential preanalytic effects whenever the result does not match the clinical symptoms. Preanalytic variables can be controllable, such as diet, exercise, and drug intake, or they can be noncontrollable, inherent to the patient's age, sex, race, or disease state.Preanalytic variables can occur at many steps in the testing process. Physicians and clinical staff can misinterpret test names and order the wrong test or methodology. Biological factors, such as fasting, may require the patient to prepare before specimen collection or a sample may need to be collected at an appropriate time for therapeutic drug monitoring or hormone interpretation. Several sources of preanalytic variation have been related to specimen collection, including patient identification, specimen additives, order of draw, sample mixing, specimen volume, phlebotomy technique, needle size, and use of vascular access devices. Delays in transportation and inappropriate storage of samples after analysis can also adversely affect test results.Some preanalytic variables can be detected, such as hemolysis, lipemia, and icterus by visual inspection of each specimen, but other sources of variation are not readily detectable. Newer analyzers can spectrophotometrically analyze each specimen for interferences due to hemolysis, lipemia, and icterus, automating the ability to comment and qualify a test result on the basis of the level of interferent. Education and awareness, however, remain an important means of managing preanalytic effects as a source of laboratory result variation.
Modifiers in Graphite Furnace Atomic Absorption Spectrometry—Mechanisms and Applications
Authors: Bulska Ewa 
Published: December 2009

AbstractThe graphite atomizer is a commonly used reactor where the sample undergoes various processes, leading to the formation of free atoms of the analyte of interest in gaseous phase. Thus atomic absorption of the cloud of atoms could be measured. This process is called atomization and depends strongly on the composition of the sample introduced into the atomizer. In graphite furnace, the sample is gradually heated according to the previously set time/temperature program so that various components of the sample could evaporate. The best conditions for atomic absorption measurements could be achieved when the matrix components evaporate before analyte atoms appear in the gaseous phase. The better the separation of the evaporation of matrix from the evaporation of analyte, less interference occurs during the measurement. It is clear that the efficiency of the separation depends on the volatilities of both matrix and analyte compounds. Generally speaking, the main aim of the modifiers is to provoke intended chemical reaction in order to enhance the separation of matrix and analyte, thus ensuring that the atomization process is free from interferences. Commonly, an excess of reagent—modifier—is added intentionally to the sample or atomizer. Its aim is to transfer the analyte into the less‐volatile compounds and/or to transfer the matrix compounds to more‐volatile compounds. Moreover, properly designed modification could also play its role in the interaction of the sample with graphite surface and/or unify the atomization process of analyte being present in various species.
In‐Beam Prompt γ‐Activation Analysis
Authors: Révay Zsolt 
Published: December 2009

Abstract
Prompt γ‐activation analysis (PGAA) is a rapidly developing nuclear analytical technique for the determination of elemental and isotopic composition. The largest neutron research centers and many smaller research reactors operate in‐beam PGAA instruments for the purpose of a wide variety of analyses. PGAA is a nondestructive analytical technique and is suitable for the analysis of light elements, especially hydrogen and boron, as well as some trace elements (e.g. rare earths and cadmium). Because of the deep penetration of both neutrons and γ‐rays, PGAA is suitable for the analysis of samples in closed containers. As the technique is nondestructive and does not require any sample preparation, it is especially useful for the investigation of precious objects (e.g. archaeological artifacts) or hazardous materials. The basic principles of the method, the instrumentation, and some basic issues of the installation, and operation of the in‐beam PGAA technique are all described in this article. A few typical applications are also introduced.
Porous Polymer Films with Gradient‐Refractive‐Index Structure for Broadband and Omnidirectional Antireflection Coatings
Authors: Li Xiao , Gao Junpeng , Xue Longjian , Han Yanchun 
Published: December 2009

AbstractPorous polymer films that can be employed for broadband and omnidirectional antireflection coatings are successfully shown. These films form a gradient‐refractive‐index structure and are achieved by spin‐coating the solution of a polystyrene‐block‐poly(methyl methacrylate) (PS‐b‐PMMA)/PMMA blend onto an octadecyltrichlorosilane (OTS)‐modified glass substrate. Thus, a gradient distribution of PMMA domains in the vertical direction of the entire microphase‐separated film is obtained. After those PMMA domains are removed, a PS porous structure with an excellent gradient porosity ratio in the vertical direction of the film is formed. Glass substrates coated with such porous polymer film exhibit both broadband and omnidirectional antireflection properties because the refractive index increases gradually from the top to the bottom of the film. An excellent transmittance of >97% for both visible and near‐infrared (NIR) light is achieved in these gradient‐refractive‐index structures. When the incident angle is increased, the total transmittance for three different incident angles is improved dramatically. Meanwhile, the film possesses a color reproduction character in the visible light range.
Tuning the Optoelectronic Properties of Carbazole/Oxadiazole Hybrids through Linkage Modes: Hosts for Highly Efficient Green Electrophosphorescence
Authors: Tao Youtian , Wang Qiang , Yang Chuluo , Zhong Cheng , Zhang Kai , Qin Jingui , Ma Dongge 
Published: December 2009

AbstractA series of bipolar transport host materials: 2,5‐bis(2‐(9H‐carbazol‐9‐yl)phenyl)‐1,3,4‐oxadiazole (o‐CzOXD) (1), 2,5‐bis(4‐(9H‐carbazol‐9‐yl)phenyl)‐1,3,4‐oxadiazole (p‐CzOXD) (2), 2,5‐bis(3‐(9H‐carbazol‐9‐yl)phenyl)‐1,3,4‐oxadiazole (m‐CzOXD) (3) and 2‐(2‐(9H‐carbazol‐9‐yl)phenyl)‐5‐(4‐(9H‐carbazol‐9‐yl)phenyl)‐1,3,4‐oxadiazole (op‐CzOXD) (4) are synthesized through simple aromatic nucleophilic substitution reactions. The incorporation of the oxadiazole moiety greatly improves their morphological stability, with Td and Tg in the range of 428–464 °C and 97–133 °C, respectively. The ortho and meta positions of the 2,5‐diphenyl‐1,3,4‐oxadiazole linked hybrids (1 and 3) show less intramolecular charge transfer and a higher triplet energy compared to the para‐position linked analogue (2). The four compounds exhibit similar LUMO levels (2.55–2.59 eV) to other oxadiazole derivatives, whereas the HOMO levels vary in a range from 5.55 eV to 5.69 eV, depending on the linkage modes. DFT‐calculation results indicate that 1, 3, and 4 have almost complete separation of their HOMO and LUMO levels at the hole‐ and electron‐transporting moieties, while 2 exhibits only partial separation of the HOMO and LUMO levels possibly due to intramolecular charge transfer. Phosphorescent organic light‐emitting devices fabricated using 1–4 as hosts and a green emitter, Ir(ppy)3 or (ppy)2Ir(acac), as the guest exhibit good to excellent performance. Devices hosted by o‐CzOXD (1) achieve maximum current efficiencies (ηc) as high as 77.9 cd A−1 for Ir(ppy)3 and 64.2 cd A−1 for (ppy)2Ir(acac). The excellent device performance may be attributed to the well‐matched energy levels between the host and hole‐transport layers, the high triplet energy of the host and the complete spatial separation of HOMO and LUMO energy levels.
p–n‐Junction‐Based Flexible Dye‐Sensitized Solar Cells
Authors: Heng Liping , Wang Xinyi , Yang Nailiang , Zhai Jin , Wan Meixiang , Jiang Lei 
Published: December 2009

AbstractIn this paper, a new type of flexible working electrode, TiO2/CuI/Cu, is reported, in which the p–n junction of TiO2–CuI is introduced into dye‐sensitized solar cells (DSSCs) for the first time. The devices give a high conversion efficiency of up to 4.73% under 1 sun illumination. The excellent performance is ascribed to the existence of the p–n junction, which forms a single directional pathway for electron transport which benefits the charge separation, and improves the efficiency of the flexible solar cells as a result.
From artifacts to aggregations: Modeling scientific life cycles on the semantic Web
Authors: Pepe Alberto , Mayernik Matthew , Borgman Christine L. , Van de Sompel Herbert 
Published: December 2009

AbstractIn the process of scientific research, many information objects are generated, all of which may remain valuable indefinitely. However, artifacts such as instrument data and associated calibration information may have little value in isolation; their meaning is derived from their relationships to each other. Individual artifacts are best represented as components of a life cycle that is specific to a scientific research domain or project. Current cataloging practices do not describe objects at a sufficient level of granularity nor do they offer the globally persistent identifiers necessary to discover and manage scholarly products with World Wide Web standards. The Open Archives Initiative's Object Reuse and Exchange data model (OAI‐ORE) meets these requirements. We demonstrate a conceptual implementation of OAI‐ORE to represent the scientific life cycles of embedded networked sensor applications in seismology and environmental sciences. By establishing relationships between publications, data, and contextual research information, we illustrate how to obtain a richer and more realistic view of scientific practices. That view can facilitate new forms of scientific research and learning. Our analysis is framed by studies of scientific practices in a large, multidisciplinary, multi‐university science and engineering research center, the Center for Embedded Networked Sensing.
Analysis of participation in an online photo‐sharing community: A multidimensional perspective
Authors: Nov Oded , Naaman Mor , Ye Chen 
Published: December 2009

AbstractIn recent years we have witnessed a significant growth of social‐computing communities—online services in which users share information in various forms. As content contributions from participants are critical to the viability of these communities, it is important to understand what drives users to participate and share information with others in such settings. We extend previous literature on user contribution by studying the factors that are associated with various forms of participation in a large online photo‐sharing community. Using survey and system data, we examine four different forms of participation and consider the differences between these forms. We build on theories of motivation to examine the relationship between users' participation and their motivations with respect to their tenure in the community. Amongst our findings, we identify individual motivations (both extrinsic and intrinsic) that underpin user participation, and their effects on different forms of information sharing; we show that tenure in the community does affect participation, but that this effect depends on the type of participation activity. Finally, we demonstrate that tenure in the community has a weak moderating effect on a number of motivations with regard to their effect on participation. Directions for future research, as well as implications for theory and practice, are discussed.
ChemInform Abstract: Syntheses and Crystal Structures of Y7Co6Sn23 and Ln5Co6Sn18 (Ln: Sc, Ho).
Authors: Lei Xiao‐Wu , Zhong Guo‐Hua , Hu Chun‐Li , Mao Jiang‐Gao 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Resistive Investigation of Pseudogap State in Non‐stoichiometric LnBa2Cu3O7‐δ (Ln: Y, Ho) Single Crystals with Account for BCS—BEC Crossover.
Authors: Vovk R. V. , Obolenskii M. A. , Zavgorodniy A. A. , Goulatis I. L. , Chroneos A. , Biletskiy E. V. 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Preparation and Photocatalytic Property of LiCr(WO4)2.
Authors: Lv Jun , Zhao Zongyan , Li Zhaosheng , Ye Jinhua , Zhou Zhigang 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Rhenium‐Catalyzed Regio‐ and Stereoselective Dimerization and Cyclotrimerization of Terminal Alkynes.
Authors: Kawata Atsushi , Kuninobu Yoichiro , Takai Kazuhiko 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Sequential Addition Reactions of Two Molecules of Grignard Reagents to Thioformamides
Authors: Murai Toshiaki , Ui Kazuki , Narengerile Narengerile 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: A Convenient and Efficient Rhenium‐Catalyzed Hydrosilylation of Ketones and Aldehydes
Authors: Dong Hailin , Berke Heinz 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Pd(PPh3)4‐PEG 400 Catalyzed Protocol for the Atom‐Efficient Stille Cross‐Coupling Reaction of Organotin with Aryl Bromides.
Authors: Zhou Wen‐Jun , Wang Ke‐Hu , Wang Jin‐Xian 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Performance of SCS Palladium Pincer Complexes in Borylation of Allylic Alcohols. Control of the Regioselectivity in the One‐Pot Borylation—Allylation Process.
Authors: Selander Nicklas , Szabo Kalman J. 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Complete Stereoretention in the Rhodium‐Catalyzed 1,2‐Addition of Chiral Secondary and Tertiary Alkyl Potassium Trifluoroborate Salts to Aldehydes.
Authors: Ros Abel , Aggarwal Varinder K. 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Catalytic Enantioselective Allylation of Dienals Through the Intermediacy of Unsaturated π‐Allyl Complexes.
Authors: Zhang Ping , Morken James P. 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Direct Synthesis of Highly Substituted 2‐Cyclohexenones and Sterically Hindered Benzophenones Based on a [5C + 1C] Annulation.
Authors: Fu Zhenqian , Wang Mang , Dong Ying , Liu Jun , Liu Qun 
Published: December 2009

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.