bluuebunny/crossref_metadata_2025_split huggingface dataset:
Visibility, Usability and Accessibility of Polish E-Commerce Websites From the B2C Sector
Authors: Gąsiorkiewicz Artur 
Published: March 2012

Visibility, Usability and Accessibility of Polish E-Commerce Websites From the B2C Sector
In the time of rapid development of Internet technologies and changing competitive environment, one of the most significant ways of creation of the e-commerce endeavor value is the increase of the incoming traffic of the internet website and the level of its conversion into business goals. Undertaking activities form the scope of internet marketing and increase of the usability and accessibility of websites are supporting this cause. However, this issues being broadly described in the literature they still have limited applications in business practice. The article presents the most important factors influencing the scope and characteristics of internet traffic that depends on the internet website owners. Issues are illustrates with research of listed factors that were performed on selected e-commerce systems from the B2C sector in Poland.
Construction of Estimates in the Choice of Alternative Solutions by Using the Fuzzy Utilities
Authors: Chernov Vladimir , Dorokhov Oleksandr , Malyaretz Ludmila 
Published: March 2012

Construction of Estimates in the Choice of Alternative Solutions by Using the Fuzzy Utilities
The problem of multi-criteria choice of alternatives with accounting the multiple stakeholders' preferences has been considered. The model for solution with the composition of fuzzy sets has been described. The mathematical formulation and justification of the solution using a fuzzy utility functions is given. Corresponding numerical calculations and graphic example are presented.
Homologies of the flower and inflorescence in the early‐divergent grass Anomochloa (Poaceae)
Authors: Sajo M. Graça , Pabón‐Mora Natalia , Jardim Jomar , Stevenson Dennis W. , Rudall Paula J. 
Published: March 2012

• Premise of the study: The grass subfamily Anomochlooideae is phylogenetically significant as the sister group to all other grasses. Thus, comparison of their structure with that of other grasses could provide clues to the evolutionary origin of these characters.• Methods: We describe the structure, embryology, and development of the flower and partial inflorescence of the monotypic Brazilian grass Anomochloa marantoidea. We compare these features with those of other early‐divergent grasses such as Pharus and Streptochaeta and closely related Poales such as Ecdeiocolea.• Key results: Anomochloa possesses several features that are characteristic of Poaceae, notably a scutellum, a solid style, reduced stamen number, and an ovary with a single ovule that develops into a single indehiscent fruit. Interpretation of floral patterning in Anomochloa is problematic because the ramification pattern of the florets places the bracts and axes in unusual positions relative to the primary inflorescence axis. Our study indicates that there is a single abaxial carpel in Anomochloa, probably due to a cryptic type of pseudomonomery in Anomochloa that resembles the pseudomonomery of other grasses. On the other hand, the Anomochloa flower differs from the “typical” grass flower in lacking lodicules and possessing four stamens, in contrast with the tristaminate condition that characterizes many other grasses.• Conclusions: Using the median part of the innermost bract as a locator, we tentatively homologize the inner bract of the Anomochloa partial inflorescence with the palea of other grasses. In this interpretation, the pattern of monosymmetry due to stamen suppression differs from that of Ecdeiocolea.
Trait convergence and plasticity among native and invasive species in resource‐poor environments
Authors: Drenovsky Rebecca E. , Khasanova Albina , James Jeremy J. 
Published: March 2012

•Premise of study:Functional trait comparisons provide a framework with which to assess invasion and invasion resistance. However, recent studies have found evidence for both trait convergence and divergence among coexisting dominant native and invasive species. Few studies have assessed how multiple stresses constrain trait values and plasticity, and no study has included direct measurements of nutrient conservation traits, which are critical to plants growing in low‐resource environments.•Methods:We evaluated how nutrient and water stresses affect growth and allocation, water potential and gas exchange, and nitrogen (N) allocation and use traits among a suite of six codominant species from the Intermountain West to determine trait values and plasticity. In the greenhouse, we grew our species under a full factorial combination of high and low N and water availability. We measured relative growth rate (RGR) and its components, total biomass, biomass allocation, midday water potential, photosynthetic rate, water‐use efficiency (WUE), green leaf N, senesced leaf N, total N pools, N productivity, and photosynthetic N use efficiency.•Key results:Overall, soil water availability constrained plant responses to N availability and was the major driver of plant trait variation in our analysis. Drought decreased plant biomass and RGR, limited N conservation, and led to increased WUE. For most traits, native and nonnative species were similarly plastic.•Conclusions:Our data suggest native and invasive biomass dominants may converge on functionally similar traits and demonstrate comparable ability to respond to changes in resource availability.
Redox Properties of Radicals
Authors: Magri David C. , Workentin Mark S. 
Published: March 2012

Abstract
The redox properties of organic radicals in solution and many techniques used to evaluate the thermodynamic and kinetic parameters of this important class of reactive intermediate are reviewed. An overview is provided of the many methods used to generate and detect radicals by direct and indirect electrochemical methods including cyclic voltammetry with microelectrodes and ultramicroelectrodes, competitive q method and alternating current voltammetry, and non‐direct photoelectrochemical methods involving intermediate generation by photochemical means and subsequent investigation by electrochemical and other complimentary techniques including photomodulated voltammetry, laser flash photoelectron injection, and pulse radiolysis. The end of the article provides detailed tables summarizing the reduction and oxidation potentials of various classes of organic radicals.
Photo Induced Radical Reactions
Authors: Pérez‐Prieto Julia , Miranda Miguel A. 
Published: March 2012

Abstract
This article discusses a number of reactions of potential synthetic interest occurring through photochemically generated organic radicals. Emphasis is placed on the nature of the resulting photoproducts, whose formation is discussed on a mechanistic basis. If available, experimental evidence (obtained by laser flash photolysis or related time‐resolved techniques) is provided. The material is organized according to the reaction types, for instance, homolytic cleavage, mesolytic cleavage, radical addition, and oxidative or reductive electron transfer. In addition to the classical carboncarbon or carbonhydrogen bond breaking processes, such as the Norrish type I reaction, the hydrogen abstraction, and the photo‐Fries or the photo‐Claisen rearrangements, a number of carbonheteroatom and heteroatomheteroatom cleavage processes are also covered. At the end of the article, a short section is included that deals with the experimental techniques for the characterization of photochemically generated radicals.
Matrix Isolation of Radicals
Authors: Mardyukov Artur , Sander Wolfram 
Published: March 2012

AbstractMatrix isolation spectroscopy is a viable tool for the isolation and characterization of free radicals. In inert media (in particular, rare gases such as argon or neon) at cryogenic temperatures (below 30 K), radicals are immobilized and kinetically stabilized. In some cases, it was also possible to investigate bimolecular reactions of matrix‐isolated radicals with small molecules. The spectroscopic characterization of simple alkyl radicals such as methyl and ethyl, of unsaturated radicals such as allyl and vinyl, and of aromatic radicals is described here.
Radical Chemistry in the Gas Phase
Authors: Alcaraz Christian , Fischer Ingo , Schröder Detlef 
Published: March 2012

AbstractWe discuss the role of isolated radicals in various chemical environments, such as combustion engines, low‐temperature plasmas, planetary atmospheres, and interstellar space. Several methods to generate radicals are presented, for example, pyrolysis, photolysis, discharges, chemical reactions, and neutralization–reionization mass spectrometry. The breadth of each method is illustrated and species generated by these methods are introduced. It is shown that photoionization is an important tool to detect radicals and unravel their reactions. However, the often small Franck–Condon‐factors have to be considered when interpreting photoionization data. Selected results on the unimolecular and bimolecular reactions of radicals are discussed with the intention to show the scope of present methods to study radical chemistry in the gas phase. Among these methods are time‐resolved laser spectroscopy, mass‐spectrometric techniques such as charge‐tagging and schemes based on detecting radicals with synchrotron radiation.
Free Radical Chemistry in Room‐Temperature Ionic Liquids
Authors: Shkrob Ilya A. , Wishart James F. 
Published: March 2012

Abstract
Ionic liquids are emerging as the largest class of room‐temperature organic liquids. These ionic compounds are composed of oddly shaped organic cations and inorganic or organic anions. Ionic liquid solvents combine such properties as electric conductivity, low volatility, and a diverse range of solute–solvent interactions. In this article, we consider the recent advances in free radical chemistry occurring in this new class of organic solvents with particular emphasis on the generation and reactions of free radicals in radiolysis, photolysis, and electrochemistry of ionic liquids.
Epoxides in Titanocene‐Mediated and ‐Catalyzed Radical Reactions
Authors: Gansäuer Andreas , Fleckhaus André 
Published: March 2012

Abstract

Epoxides are among the most useful functional groups in organic chemistry. They are also excellent radical precursors. Ring opening can be achieved via electron transfer from low valent metal complexes. As yet, titanocene(III) chlorides have emerged as the most useful reagents in this respect. Catalytic reaction conditions have been described that exploit the stability of radicals under protic conditions. The use of enantiomerically pure titanocenes has resulted in a number of applications in enantioselective catalysis. Most recently, this has been demonstrated in enantioselective cyclizations. Other unexpected developments have been reported in the field of hydrogen atom transfer reagents for the reduction of radicals generated from epoxides. Titanocene bound water acts as an excellent hydrogen atom transfer (HAT) reagent. Moreover, H
2
can be employed as terminal reductant when activated by “hydrogenation” catalysts, such as RhCl(PPh
3
)
3
.

The most common application of the titanocene‐mediated or ‐catalyzed epoxide opening is in cyclization reactions. It has been demonstrated that cyclopropanes, cyclobutanes, cyclopentanes, cyclohexanes, and cycloheptanes are readily accessible. It is expected that these cyclizations will be increasingly frequently applied in the synthesis of natural products.
Charge Transfer in DNA
Authors: Fujitsuka Mamoru , Majima Tetsuro 
Published: March 2012

AbstractCharge transfer in DNA attracts substantial attentions of researchers in wide fields, especially in the fields of bioscience, nanotechnology, physical chemistry, and so on. During the charge transfer in DNA, hole and excess electron play important roles as charged species in the conduction mechanism. It has been revealed that two kinds of electron transfer mechanisms have to be considered to explain the process of hole transfer in DNA, that is, tunneling and hopping mechanisms. The tunneling mechanism, which is governed by the Marcus theory, is important when the distance for the charge transfer is short (normally less than three nucleobase pairs). On the other hand, by the hopping mechanism, which can be described by the one‐dimensional random walk model, long‐range hole migration in DNA becomes possible. In the case of excess electron transfer, on the other hand, contribution of both tunneling and hopping mechanisms to conduction mechanism has been indicated. In this article, we summarize the mechanistic studies on charge transfer in DNA as well as its application.
Electron Transfer in Peptides and Proteins
Authors: Giese Bernd , Eckhardt Sonja , Lauz Miriam 
Published: March 2012

AbstractElectron transfer (ET) is a basic chemical reaction, which involves radicals and radical ions. In all living organisms, ETs through peptides and proteins are vital for energy conversion and metabolic processes. In several cases, distances are so long that ET cannot occur as a single‐step reaction, and the process is a result of a multistep reaction, where the charge hops between relay stations. Each of the hopping steps obeys the Marcus theory with its strong distance dependence, but the overall process is described by the weak distance dependency of diffusion. Aromatic and sulfur‐containing aliphatic amino acids are relay amino acids, and for special peptide conformations also the amide bonds might act as stepping stones. ET rates depend on peptide conformations, redox potentials, dipole moments, charges, and proton transfer processes. In addition to its fundamental biological importance, ET also starts to play a role as electronic material. In this article, the basic principles, ET in biological systems, and the possible applications in materials science are presented and discussed.
Theoretical Studies of Radical Enzymes
Authors: Sandala Gregory M. , Smith David M. , Radom Leo 
Published: March 2012

AbstractThe understanding of the mechanisms of radical enzymes has benefited greatly from the contribution of theoretical computations. This review highlights the success for a series of selected examples within this broad field. For the coenzyme B12‐dependent enzymes, theoretical investigations have provided explanations for the activation of the Co–C bond of coenzyme B12, the facilitation of the otherwise difficult rearrangement step, and how the inherent stability of the participating radical intermediates can profoundly affect the level of catalysis. Likewise, computational investigations have characterized intermediates and demonstrated the importance of certain active‐site amino acid residues in the reactions catalyzed by pyruvate formate lyase, benzylsuccinate synthase, and class III ribonucleotide reductase. In the case of methyl‐coenzyme M reductase, the use of theory has offered new mechanistic ideas as to how this enzyme operates, which can then be tested experimentally. Overall, it is clear that the combination of experimental and computational investigations provides an excellent and highly synergistic approach to elucidate the cause‐and‐effect actions that govern the workings of the fascinating world of radical enzymes.
Free Radicals and Metabolic Disorders
Authors: Cohen Guy , Riahi Yael , Sasson Shlomo 
Published: March 2012

AbstractThe termmetabolic disordersusually describes an altered capacity of the organism to use exogenous and endogenous nutrients and metabolites to generate energy, maintain normal cell structure and function, and support controlled cell proliferation. Normal metabolism starts with the absorption of nutrients and ends with the elimination of metabolites and compounds released following multiple enzyme‐mediated reactions. Complex intra‐ and intercellular pathways control a large array of metabolic interactions that allow the organism to function normally and to adapt to environmental and nutritional challenges. These regulatory interactions involve regulation of enzymes' catalytic functions, organ cross‐talk, hormones, and neural inputs. Metabolic disorders occur when these reactions and control mechanisms are disrupted. The metabolic syndrome is associated with peripheral insulin resistance and hypertension that further deteriorate to overt type‐2 diabetes (T2D) and cardiovascular disease. Obesity is a major risk factor for the development of metabolic disorder. A major contributing and exacerbating factor in the etiology of these complications is an imbalanced and excessive production of free radicals, which interact with and modify substrates and proteins of major metabolic and regulatory pathways. This article aims at presenting the main mechanism of free‐radical generation under normal conditions and in metabolic disorders, such as T2D and obesity. The impact of the oxidative stress on the metabolism, cell functions, and end‐organ complications is discussed.
Sb, Bi, Te, and I‐Transfer Polymerization and Applications
Authors: Yamago Shigeru , Kayahara Eiichi 
Published: March 2012

AbstractSynthetic and mechanistic aspects of organostibine‐, organobismuthine‐, organotellurium‐, and organoiodine‐mediated living radical polymerization are discussed. These methods predominantly proceed by the degenerative chain‐transfer mechanism for the activation/deactivation of the dormant/radical species, while reversible termination by thermolysis and photolysis of carbon–heteroatom bonds also contributes to a small extent. The high reactivity of these heteroatom compounds, especially Sb, Bi, and Te compounds, ensures the high control of molecular weight and molecular weight distribution of the resulting polymers. Addition of several inorganic and organic heteroatom compounds considerably increases the control of the polymerization by altering the activation/deactivation mechanism to the reversible chain transfer‐catalyzed polymerization. These methods possess several synthetic advantages, such as high versatility of monomer families, high versatility of block copolymer synthesis, high compatibility of polar functional groups and solvents, and high versatility for selective synthesis of end‐functionalized polymers. These characteristics offer excellent opportunities for the synthesis of new polymeric materials for various applications.
Physical Properties of Thiazyl Radicals Toward Conductive and Magnetic Materials
Authors: Awaga Kunio 
Published: March 2012

Abstract
Heterocyclic thiazyl radicals possess unique chemical and physical properties, as building blocks for molecule‐based conductors, superconductors, and magnetic materials. They do not need protecting groups on their molecular skeletons, so that the lack of such substituents permits close packing in the solid state. Moreover, thiazyl radical solids often involve a multidimensional network consisting of π–π overlaps and S⋯N contacts. In this article, we describe various physical properties of thiazyl radicals such as drastic phase transitions, ferromagnetic couplings, nonlinear transport, and high photoconductivities. They are highly expected to be utilized in developing organic electronics/spintronics.
The History of Free Radical Chemistry
Authors: Tidwell Thomas T. 
Published: March 2012

AbstractSuggestions of free radicals before 1900 were realized with the discovery first of the triphenylmethyl radical, and then unstabilized aliphatic radicals in the twentieth century. The finding of new types of radicals and the development of their chemistry are outlined. Many individuals participated in the advance of free‐radical chemistry, and some of the most prominent original contributors are recognized where possible. The article provides an overview of the development of many fundamentals of free radicals, while the definitive articles in this encyclopedia on the various topics provided by leaders in their study articles describe the current state of knowledge.
Nitroxides in Synthetic Radical Chemistry
Authors: Tansakul Chittreeya , Braslau Rebecca 
Published: March 2012

AbstractNitroxides are persistent organic free radicals utilized in synthesis as carbon radical trapping agents and as oxidants. Since nitroxides trap carbon radicals at close to diffusion‐controlled rates, carbon radicals are either trapped directly or undergo fast cyclizations or rearrangements before trapping. The resulting alkoxyamines are typically reduced to the alcohol or oxidized to the ketone. Alkoxyamines bearing radical‐stabilizing groups on the alkyl fragment undergo reversible homolysis on heating, allowing cyclizations or intermolecular olefin additions based on the persistent radical effect. Nitroxides are widely used as oxidants, either by a single electron transfer mechanism or, most commonly, via the oxoammonium salt. Oxoammonium salts oxidize alcohols by two different mechanisms, depending on the pH. Strongly acidic conditions favor oxidation of secondary over primary alcohols, whereas mild acidic or basic conditions give the opposite selectivity. The oxoammonium can be utilized stoichiometrically or catalytically with a primary cooxidant. Optically active nitroxides effect kinetic resolution and desymmetrization. Sulfides, allylic CH bonds, and benzylic ethers also undergo oxidation. Activation of nitroxides by complexation with metals provides an electrophilic oxygen trap for nucleophiles such as enamines and hydride. Electron‐poor nitroxides abstract activated hydrogens, and add to phenols, resulting in quinone formation.
Fundamentals of Controlled/Living Radical Polymerization
Authors: Matyjaszewski Krzysztof 
Published: March 2012

Abstract
Principles and special features of controlled/living radical polymerization (CRP) processes such as nitroxide‐mediated polymerization (NMP), organometallic radical polymerization (OMRP), and atom transfer radical polymerization (ATRP) and degenerative transfer (DT) processes such as reversible addition‐fragmentation transfer (RAFT) systems are discussed. CRP is critically compared with conventional radical polymerization. Proportion of terminated chains in CRP as a function of polymerization rate, conversion, targeted degree of polymerization, and monomer concentration is described and compared for ATRP and DT processes. Concept of persistent radical effect is introduced and its application to determine equilibrium constants in NMP and ATRP is presented. Current challenges and future perspectives are briefly discussed.
Tin Hydrides and Functional Group Transformations
Authors: Jasch Hannelore , Heinrich Markus R. 
Published: March 2012

AbstractTin hydrides have played an important role in the development of radical chemistry. Despite their comparatively late discovery as reagents for radical reactions in the late 1950s, they have since then had a tremendous impact.After a short historical introduction including two milestones in tin hydride radical chemistry, an overview is given of the manifold applications tin hydrides are useful for. Starting from the preparation of the classic tin hydrides, new variants are presented along with their advantages over the traditional reagents. In relation to simple radical reductions, for which tin hydrides are popular reagents because of their hydrogen‐donor abilities, we show which functional groups are suited for the tin‐mediated generation of radicals. If those radicals are not immediately reduced by the tin hydride, a large number of group transformations can be performed ranging from simple cyclizations to complex rearrangements or domino reactions.