bluuebunny/crossref_metadata_2025 huggingface dataset:
Benefits of mixing timothy with alfalfa for forage yield, nutritive value, and weed suppression in northern environments
Authors: Bélanger Gilles , Castonguay Yves , Lajeunesse Julie
Published: October 2013

Bélanger, G., Castonguay, Y. and Lajeunesse, J. 2014. Benefits of mixing timothy with alfalfa for forage yield, nutritive value, and weed suppression in northern environments. Can. J. Plant Sci. 94: 51–60. Alfalfa can be grown alone or with a grass, but little information exists on the benefits of mixing alfalfa (Medicago sativa L.) with a grass in northern environments. Our objectives were (1) to determine the benefits in terms of forage yield, nutritive value, and weed suppression of mixing timothy (Phleum pratense L.) with alfalfa and (2) to evaluate the persistence of alfalfa cultivars of varied adaptation to cold and of alfalfa populations selectively improved for superior freezing tolerance in a grass–legume mixture and in monoculture. This study was conducted in a region with 1700 degree-days (5°C basis) with one harvest in the seeding year (2008), three harvests in each of two post-seeding years, and one harvest in the third post-seeding year. Adding timothy to alfalfa increased the seasonal total dry matter (DM) yield by an average of 0.57 Mg DM ha−1 yr−1 in the first 2 post-seeding years and this seasonal effect was due mostly to a DM yield increase at the first harvest. The weed contribution to total DM yield in the three harvests of the first 2 post-seeding years was greater in the alfalfa monoculture (16 to 47%) than in the alfalfa–timothy mixture (12 to 36%). Mixing timothy with alfalfa also increased neutral detergent fibre concentration and digestibility, decreased N concentration, and tended to increase water soluble concentration, but had little effect on forage DM digestibility. Cultivars and populations recurrently selected for superior freezing tolerance did not differ in persistence and had a limited effect on DM yield and nutritive value attributes. The positive effect on DM yield of mixing timothy with alfalfa was not accompanied by a reduction in forage digestibility that is usually observed with increased DM yield.
Consumer research explores acceptability of a new Canadian apple – Salish™
Authors: Cliff Margaret A. , Stanich Kareen , Hampson Cheryl
Published: October 2013

Cliff, M. A., Stanich, K. and Hampson, C. 2014. Consumer research explores acceptability of a new Canadian apple – Salish™. Can. J. Plant Sci. 94: 99–108. This research compared consumer preferences for a new Canadian apple, Salish™ (cultivar SPA493), with commercial cultivars using data collected at two University of British Columbia Apple Festivals (2008, 2010). Mean acceptability by mouth and visual acceptability scores for Salish™ were compared with those for each of three tart (subacid/acid) cultivars (Granny Smith, McIntosh, Spartan) (2008, n ≈ 165) and two relatively new cultivars (Ambrosia, Honeycrisp) (2010, n=1182). T-tests on the 2008 data (n ≈ 165) revealed that Salish™ had higher consumer acceptability than Granny Smith and McIntosh. Analysis of variance of the 2010 data evaluated the influence of ethnicity (ancestral origin), age, gender and stated apple preference (sweet, tart), for the two largest sub-groups of consumers (Asian ethnicity, n=353 European ethnicity, n=725). While 88% of consumers of Asian ethnicity categorized themselves as sweet apple eaters, consumers of European ethnicity were both sweet (55%) and tart (45%) apple eaters. The sweet apple eaters rated Ambrosia higher in acceptability by mouth than Salish™, while tart apple eaters preferred Salish™. On average, consumers’ stated apple preference (sweet, tart) was consistent with their acceptability scores. Mean acceptability by mouth scores for consumers of Asian ethnicity were higher for Ambrosia and lower for Salish™ as compared with consumers of European ethnicity. The visual acceptability of red apples with a green ground (background) colour was significantly lower than those with a yellow ground colour. This suggested that sweet apple eaters of both ethnicities had a strong negative bias for apples with a slightly green ground colour. The work will assist industry in releasing and appropriately marketing cultivars to selected consumers in the metropolitan marketplace.
Characteristics of cloud liquid water path from SEVIRI on the Meteosat Second Generation 2 satellite for several cloud types
Authors: Kniffka A. , Stengel M. , Lockhoff M. , Bennartz R. , Hollmann R.
Published: October 2013

Abstract. In this study the temporal and spatial characteristics of liquid water path (LWP) of low, middle level and high clouds are analysed using space-based observations of the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard the Meteosat Second Generation 2 (MSG2) satellite. Both geophysical quantities are part of the dataset CLAAS (CLoud property dAtAset using SEVIRI) and are generated by EUMETSAT's Satellite Application Facility on Climate Monitoring (CM SAF). In this article we focus on the statistical properties of LWP retrieved at daylight associated with the individual cloud type. Our results reveal that each cloud type possesses a characteristic LWP distribution. These frequency distributions are constant with time in the entire SEVIRI field of view, but vary for smaller regions like Central Europe. The average LWP is higher over land than over sea, in case of low clouds 15–27% for 2009 and the variance of the frequency distributions is enhanced. Also, the average diurnal cycle of LWP is related to cloud type where most pronounced diurnal variations were detected for middle level clouds. With SEVIRI it is possible to distinguish between intrinsic LWP variability and variations driven by cloud amount. The relative amplitude of the intrinsic diurnal cycle can exceed the cloud amount driven amplitude.
Electron acceleration at Jupiter: input from cyclotron-resonant interaction with whistler-mode chorus waves
Authors: Woodfield E. E. , Horne R. B. , Glauert S. A. , Menietti J. D. , Shprits Y. Y.
Published: October 2013

Abstract. Jupiter has the most intense radiation belts of all the outer planets. It is not yet known how electrons can be accelerated to energies of 10 MeV or more. It has been suggested that cyclotron-resonant wave-particle interactions by chorus waves could accelerate electrons to a few MeV near the orbit of Io. Here we use the chorus wave intensities observed by the Galileo spacecraft to calculate the changes in electron flux as a result of pitch angle and energy diffusion. We show that, when the bandwidth of the waves and its variation with L are taken into account, pitch angle and energy diffusion due to chorus waves is a factor of 8 larger at L-shells greater than 10 than previously shown. We have used the latitudinal wave intensity profile from Galileo data to model the time evolution of the electron flux using the British Antarctic Survey Radiation Belt (BAS) model. This profile confines intense chorus waves near the magnetic equator with a peak intensity at ∼5° latitude. Electron fluxes in the BAS model increase by an order of magnitude for energies around 3 MeV. Extending our results to L = 14 shows that cyclotron-resonant interactions with chorus waves are equally important for electron acceleration beyond L = 10. These results suggest that there is significant electron acceleration by cyclotron-resonant interactions at Jupiter contributing to the creation of Jupiter's radiation belts and also increasing the range of L-shells over which this mechanism should be considered.
SERVICE LIFE DETERMINATION OF NITRILE O-RINGS IN HYDRAULIC FLUID
Authors: Pazur R. J. , Cormier J. G. , Korhan-Taymaz K.
Published: October 2013

The service life of nitrile O-rings exposed to hydraulic fluid was determined by accelerated aging at nine temperatures and four immersion times. Tensile mechanical properties (elongation and low strain modulus), volume swell, compression set, and chemical crosslink density by solvent swell were measured. Calculated activation energies based on Arrhenius rate behavior ranged from 52 to 65 kJmol−1, approximately 20–30 kJmol−1 lower than nitrile rubber heat aged in air environments. Using a 50% loss of elongation as a failure criterion, an estimate of 15 yr of service life at 23 °C was calculated. This corresponds to a compression set of 50% and an increase of approximately 30% of the chemical crosslink density. Replacement of the plasticizer with the mineral oil and its additives increased total inorganic levels in degraded O-rings as measured by thermogravimetric analysis. Besides additional sulfur and sodium, energy dispersive spectroscopy identified the presence of phosphorous, chlorine, and potassium. Hydraulic oil additives are likely responsible in facilitating the O-ring degradation through lower energy pathways that accelerate nitrile rubber hardening.
NATURAL RUBBER/CARBON BLACK NANOCOMPOSITES PREPARED BY ULTRASONICALLY AIDED EXTRUSION
Authors: Choi Jaesun , Isayev Avraam I.
Published: October 2013

Significant efforts have been made in rubber research to improve the dispersion of carbon black (CB) in rubbers to achieve better processibility and performance of tires and rubber products. In addressing these issues, the present study is an attempt to further improve the processibility and dispersion by means of application of ultrasonic waves. Natural rubber (NR)/CB nanocomposites at loadings from 15 to 60 phr were prepared by ultrasonically aided extrusion at ultrasonic amplitudes up to 7.5 μm. A die pressure significantly decreased with an increase of amplitude, especially at higher loadings, indicating an improvement in processibility. Ultrasonic power consumption was almost insensitive to loadings. The complex dynamic viscosity, storage, and loss moduli of compounds and vulcanizates at loadings of 15, 25, 35, and 60 phr were reduced by the ultrasonic treatment at an amplitude of 7.5 μm, indicating NR chain scission. Bound rubber in compounds decreased by the ultrasonic treatment. The maximum torque in curing curves, cross-link density, gel fraction, hardness, M100, M300, tensile strength, and abrasion resistance of vulcanizates at loadings of 15, 25, 35, and 60 phr decreased at an amplitude of 7.5 μm, due to the NR chain scission, whereas the elongation at break increased. Atomic force microscope (AFM) studies of vulcanizates showed a penetration of rubber chains into agglomerates at an amplitude of 7.5 μm, indicating an improvement of dispersion of CB. Based on AFM images, a dispersion index was introduced, showing that the ultrasonic treatment at an amplitude of 7.5 μm led to a better dispersion of CB in vulcanizates. Comparison of NR/CB compounds and vulcanizates with those of NR/carbon nanotube (CNT) of an earlier study was carried out. In general, the CB-containing NR showed significantly lower modulus and abrasion resistance but higher tensile strength and bound rubber than CNT-containing NR.
Fibrinolytic treatment of ST-elevation myocardial infarction
Authors: Huber K. , Halvorsen S.
Published: October 2013

Primary percutaneous coronary intervention (PPCI) is the preferred reperfusion therapy in ST-elevation myocardial infarction (STEMI), as long as it can be delivered within 90-120 minutes from patient’s first medical contact, and is the leading reperfusion strategy in most European countries. However, as PPCI cannot be offered in a timely manner to all patients, fibrinolytic therapy (FT) is the recommended choice in patients with an anticipated delay to PPCI of >90-120 minutes, presenting early after symptom onset and without contra-indications. FT should preferably be started in the pre-hospital setting. Following FT, all patients should be transferred to a PCI-center for rescue PCI or routine coronary angiography with PCI as indicated. Such a pharmaco-invasive strategy, combining FT with invasive treatment, has recently been shown to be non-inferior to PPCI in patients living in areas with long transfer delays to PCI (>60 minutes).

In this overview, we will briefly present the evidence for the benefit of FT in STEMI, and discuss the role of FT in the current era of PPCI as well as the optimal treatment following pharmacologic reperfusion.
Study of Electromagnetic Multipole Transition Half-Lives of One-Hole 15O–15N and One-Particle 17O–17F Mirror Nuclei
Authors: Pahlavani Mohammadreza , Firoozi Behnam
Published: October 2013

Energy spectrum and wave functions are obtained numerically with a potential consisting of Woods-Saxon, Coulomb, and spin-orbit coupling parts for the nuclei 15O, 15N, 17O, and 17F. The radial parts of the wave functions are used to calculate some matrix elements of electromagnetic transitions. These results are applied to calculate half-lives of low-lying exited states in the one-particle 17O and 17F as well as in the one-hole 15O and 15N isotopes. The calculated half-lives are compared with available experimental and theoretical results based on harmonic oscillator wave functions and Weisskopf units. In comparison with the results calculated from the other methods, our results based on the Woods-Saxon potential indicate a satisfactory agreement with accessible experimental data.
Ionic Liquids Based on Hexachloridometalate(V) Anions (Sb, Nb and Ta) and Nitrile-functionalized Pyridinium Cations
Authors: Xie Tao , Guan Zong , Pook Niels-Patrick , Gjikaj Mimoza
Published: October 2013

Single crystals of 1-(cyanoethyl)-3-methyl-pyridin-1-ium hexachloridoantimonate(V) (1), 1- (cyanomethyl)-3-methyl-pyridin-1-ium hexachloridoniobate(V) (2), 1-(cyanomethyl)-3-methylpyridin- 1-ium hexachloridotantalate(V) (3), 1-(cyanopropyl)-3-methyl-pyridin-1-ium hexachloridoniobate( V) (4), and 1-(cyanopropyl)-3-methyl-pyridin-1-ium hexachloridotantalate(V) (5) have been synthesized and characterized by X-ray diffraction. Compounds 1-3 crystallize in the triclinic space group P1̄ with Z = 2, and compounds 4 and 5 in the monoclinic space group C2/c with Z = 8. FTRaman spectra have been recorded and interpreted, especially with respect to the anions [MCl6]-. In addition, NMR spectra, a study of the melting behavior and elemental analyses complete the characterization.
International Development Studies, Theories and Methods in Research and Practice
Authors: Jezerská Zuzana
Published: October 2013

Sumner, A., Tribe, M. (2010): International Development Studies, Theories and Methods in Research and Practice, Los Angeles/London/New Delhi/ Singapore/Washington: Sage, 176 pages.
Po kapitalizme. Ekonomická demokracia
Authors: Koudelka Josef
Published: October 2013

Schweickart, D. (2010): Po kapitalizme. Ekonomická demokracia, Bratislava: Vydavateľstvo Spolku slo- venských spisovateľov, 208 pages.
Election Polls and Media Bias in the Czech Republic
Authors: Hrbková Lenka , Chytilek Roman
Published: October 2013

The article explores the influence of the electoral polls on media coverage of political actors during election campaigns. Based on the presumptions of the structural media bias theory we investigate whether the polls can affect the way media report on particular political actors in the course of an electoral campaign. According to Zaller’s media politics theory journalists are supposed to pay most attention to the candidate or political party leading in the polls. Also, the tone of media coverage of the leading candidate should be linked with his/her success in the race. This article adjusts the hypotheses of media politics to the condition of proportional party representation. The aim is to explore how media coverage of the non-parliamentary party Věci veřejné related to its position in the polls and its anticipated importance for future development after the election.
Negative Campaigning and Political Cynicism in the Czech Republic
Authors: Lebedová Eva
Published: October 2013

With reference to ideas presented in the theory of media malaise, the article aims to assess the role of negative campaigning in Czech elections and to analyse how it is perceived by voters, how it correlates with electoral preferences, and other important variables. The analysis is based on data from the Czech Election Survey 2010. The author draws from the causal relationship formulated in the above mentioned theory, according to which the effect of the news media and their emphasis on negative news and negativity contribute to growing political cynicism among citizens. Negative and conflicting media news, which are even more intense during election campaigns, activate the spiral of public cynicism and cause public trust in political actors to fall, as well as alignment and voter turnout (Cappella and Jamieson 1997). The author attempts to test the hypothesis: The more people watch the media and the more they are exposed to election campaign coverage, the greater is their political cynicism.
On Two Books about “Parliamentarism”
Authors: Kubát Michal
Published: October 2013

This text is a short reflection on the possibility of studying historical events through a political science approach. The two analyzed publications exemplify the possibility and the failure of such an approach. While the first book presents a coherent political science analysis of the past, the second publication fails to do so. In my text, I argue that by using appropriate theoretical foundations and methodological approaches, politics in the past can not only be effectively examined but that relevant conclusions can be reached as well.
Czech Senate Electoral Districts
Authors: Antoš Marek
Published: October 2013

The members of the Czech Senate, the upper chamber of the Czech Parliament, are elected every six years through a two-round majority system in 81 single-seat electoral districts, with one-third of the chamber up for election every two years. District boundaries are set by a law which stipulates they must be modified by amendment if the number of inhabitants in any district diverges more than 15 % from the average. Recently, these changes have been carried out every two years shortly before the regular election is announced, and the number of districts affected by changes is gradually increasing. The extent of these changes, however, is usually very small, which makes later changes necessary. During last ten years, many districts have been changed more multiple times. It follows that the Samuels-Snyder index of malapportionment has increased from 0.0289 in 1996 to 0.0346 in 2010. Moreover, during the last electoral cycle, the 15% limit was not in fact observed in four of the 81 districts. Moreover, the criterion chosen for district size is not an optimal one, as it fails to take into account the uneven distribution of minors and foreigners, who do not have voting rights. In fact, the percentage of minors and foreigners in various districts varies in the interval and , respectively. This affects the weight of votes in various districts accordingly. Besides the problems with malapportionment, the law does not provide for any prevention of gerrymandering. Although there is no strong evidence of gerrymandering being used so far, at least one attempt in this respect was made in 2008. The article analyzes the law and its outcome and suggests some modifications to the law.
Stability of Peace Processes and Factors that Influence them: the Case of Liberia
Authors: Kučerová Mária
Published: October 2013

This article deals with the issue of the peace-building process in countries with long-standing civil wars and the factors that might influence such processes. Based on my analysis, I identify two types of factors that might influence the peace process: power-sharing arrangements as an institutional factor, and attitudes of internal actors of the peace process as an agency factor. In this article I analyze the peace-building process in the West African country of Liberia. The peace-building process is analyzed through the study of the two main peace treaties signed to end the Liberian civil war in the 1990s: the Treaties of Abuja and Accra. In the analysis, I focus mainly on the extent to which the peace treaties incorporate the elements of power-sharing as well as the motivations, decision-making, and behavior of internal actors involved in the peace building process during the implementation of the peace treaties. The goal of this analysis is to reveal which dominant factor influenced the stability of the peace-building process in Liberia.
Dealing with the Legacy of Authoritarianism
Authors: Bezák Tomáš
Published: October 2013

Pinto, A.C.; Morlino, L. (eds.) (2011). Dealing with the Legacy of Authoritarianism, London and New York: Routledge, 195 pages.
Panebianco’s Organizational Model and its Applicability on the Transformation of Communist Parties in the West Europe
Authors: Mejstřík Martin
Published: October 2013

The paper deals with the organizational model of political parties created by Italian political scientist Angelo Panebianco. For presentation of this, outside Italian academic discourse, an „unknown“ model is necessary to briefly describe the whole organizational theory and to introduce the review of this model. After that we examine the applicability of Panebianco ́s scheme on the structural transformation of communist political parties at the end of 1980s. This suitability will be measured on the case example of the Italian Communist Party (PCI). The PCI was historically the strongest and most influential communist party outside the Soviet bloc and that is why it is convenient to apply the organizational model to the organizational changes of the PCI during its transformation. We also define five main criteria of these changes and their compatibility with the Panebianco ́s model. Thus the main aim of this paper is to prove the suitability of the organizational model not only to the structural transformation of the Italian communists but using this case example also to the universal transformation of the communist parties in the western world.
The Issue of the Temelín Nuclear Power Plant Completion in the Czech Political and Public Discourse
Authors: Tichý Lukáš
Published: October 2013

The issue of the Temelín nuclear power plant completion, which will have significant implications for the future of the Czech economy and energy sector, is currently one of the most debated political, security and economic questions in the Czech Republic. The main goal of this article is to define basic themes in Czech political discourse on completion of the Temelín nuclear power plant. The second aim of the article is to analyze development of Czech public discourse on the construction of the third and fourth block at the Temelín nuclear power plant. Methodologically, the article is based on thematic and content analysis. The period spanning from August 2009 to July 2012 is investigated.
Global Energy Security and American Hegemony
Authors: Jirušek Martin
Published: October 2013

Stokes, D., Raphael, S. 2010. Global Energy Security and American Hegemony, Baltimore: The John Hopkins University Press. 280 pages.
Gladiopycnodontidae, a new family of pycnodontiform fishes from the Late Cretaceous of Lebanon, with the description of three genera
Authors: Taverne Louis , Capasso Luigi
Published: October 2013

The osteology of Gladiopycnodus karami gen. et sp. nov., of Monocerichthys scheuchzeri gen. et sp. nov. and of Rostropycnodus gayeti gen. et sp. nov., three new fossil fishes from the marine Cenomanian (Late Cretaceous) of Lebanon, is studied in detail. Some of their cranial characters and the presence of a postcoelomic bone clearly refer these fishes to the order Pycnodontiformes. However, they differ from all other described Pycnodontiformes by two important characters. Their snout is elongated as a rostrum, formed by the enlarged prefrontal and the toothless premaxilla, with this premaxilla sutured by its upper margin to the lower margin of the prefrontal. Their pectoral fin is replaced by a strong spine articulated with the cleithrum. These two apomorphies justify the erection of a new family, the Gladiopycnodontidae. The skull of Monocerichthys scheuchzeri sp. nov. does not differ greatly from a classical pycnodontiform skull and this species seems to be the more primitive member of this new family. Gladiopycnodus karami gen. et sp. nov. and Rostropycnodus gayeti gen. et sp. nov. are much more specialized. They share some apomorphies not present in Monocerichthys scheuchzeri gen. et sp. nov., i. e., an extremely long rostrum and an elongated first anal pterygiophore that sustains with the postcoelomic bone a strong and long anal spine. Gladiopycnodontidae fam. nov. and Coccodontidae share a series of apomorphies that justify the erection of a new superfamily, Coccodontoidea, grouping these two families.
Social Integration and Workplace Industrial Relations
Authors: Schmidt Werner , Müller Andrea
Published: October 2013

This paper tackles the question of how social integration of migrant and native employees takes place in German industry and what role workplace industrial relations play in it. Three company case studies in manufacturing based on expert interviews with management representatives and works councillors, interviews and group discussions with employees of different origin, employee surveys, as well as company statistics, were used to explore this issue. The paper analyzes the social structure of the investigated companies, examines the interaction of employees of different origin and the role workplace industrial relations play in fostering cooperation and social integration. The case studies show that migrants are more likely to be positioned in the lower ranks of the companies’ social structure. Findings suggest, however, that this is primarily a consequence of the migrants having insufficient vocational training, which is probably the result of discrimination outside and at the threshold of the companies rather than a sign of direct discrimination within the companies. Nevertheless, the interviews and surveys show that there is employee resentment against people of different origin. There is a coexistence of resentment on the one hand and good cooperation on the other. Work requirements and the works councils’ and managements’ “internal universalism” (i.e. an orientation towards equal treatment of employees and the interdiction of discrimination within the companies) foster collegial cooperation among employees. German co-determination favours an employee model of interest representation which encourages individuals to choose a work-related identity and labour solidarity to assert their interests rather than identities related to ethnic groups. It is argued that this framework and the daily interaction of the employees eventually evoke feelings of collegiality and foster social integration.
Chiral Auxiliaries in Drug Synthesis
Authors: Chang Stanley , Halperin Shira D. , Moore Jarod , Britton Robert
Published: October 2013

The growing proportion of drugs reaching the market as single enantiomers has placed an increasing demand on the discovery of robust asymmetric methods for their synthesis. Consequently, chiral catalysis, separations, salt resolutions, and auxiliary‐controlled reactions have now largely replaced the chiral‐pool approach to synthesizing enantiomerically pure drugs. Although chiral auxiliaries may seem antiquated in light of the increasing scope of asymmetric catalysis, the chiral auxiliary approach is still optimal for a variety of key synthetic transformations and continues to play an important role in both drug discovery and development. This chapter provides a survey of chiral auxiliaries used in the synthesis of drugs, with examples chosen based on their demonstrated utility on scale.
Application of Microreactor Methodology for Organic Synthesis
Authors: Watts Paul , Wiles Charlotte
Published: October 2013

Microreactor technology is an emerging technique that enables those working in research and development to screen reactions rapidly using continuous flow, leading to the identification of reaction conditions that are suitable for use at a production level. Furthermore, in addition to using conventional reaction methodology, the inherent safety associated with the use of small reactor volumes enables users to employ reaction conditions previously thought to be too hazardous for use within a production environment.
Asymmetric Michael Addition and Related Reactions
Authors: Li Pengfei , Wang Jun , Kwong Fuk Yee
Published: October 2013

The recent developments of catalytic asymmetric Michael‐type addition of 1,3‐dicarbonyl compounds to α,β‐unsaturated ketone (enone) are described. The applications of this methodology to the synthesis of several natural products and biologically active intermediates, such as the strychnos alkaloids, magnolione analogs, and wanfarin anticoagulant, are reviewed. The first part of this chapter discusses the catalytic asymmetric Michael addition of malonate and β‐keto ester to cyclic enone for the syntheses of the strychnos alkaloids (tubifolidine, tubifoline, and strychnine) and magnolione analogs (methyl dihydrojasmonate). The second part underlines the one‐step synthesis of optically active warfarin anticoagulantviacatalytic asymmetric Michael addition of 4‐hydroxycoumarin to benzylideneacetone.
Transition‐Metal–Catalyzed AsymmetricC–CCross‐Couplings in Stereoselective Synthesis
Authors: Sarli Vasiliki
Published: October 2013

The efficient formation of carbon–carbon bonds remains a critical challenge in organic chemistry. Over the last decades, metal‐catalyzed cross‐couplings such as Heck, Suzuki‐Miyaura, Sonogashira, and Negishi reactions, as well as asymmetric allylic alkylation and alkylation/arylation of ketones, have evolved into valuable tools for forming carbon–carbon bonds. In this chapter, we summarize applications of such processes in the asymmetric synthesis of natural products and pharmaceuticals.
Ring Contraction Reactions in the Total Synthesis of Biologically Active Natural Products
Authors: Silva Luiz F.
Published: October 2013

Strategic reactions in synthetic organic chemistry are those that increase the molecular complexity of the starting material. Particularly important are the transformations where new carbon–carbon bonds are formed. Although during a ring contraction the number of carbon–carbon bonds is conserved, the reorganization of the skeleton may occur with a high level of selectivity leading to a product not easily accessed by other methods. Even highly strained systems can be obtained using the Favorskii and Wolff rearrangements. Additionally, a ring contraction approach opens new applications for the chiral pool and for readily available starting materials. This chapter presents ring contraction reactions as an efficient tool in the stereoselective synthesis of biologically active natural products. The reactions discussed are Favorskii rearrangement, oxidative rearrangements, Wolff rearrangement, thermolysis of aryliodonium ylides, and rearrangements through cationic and radical intermediates.
Electrocyclic Reactions in Stereoselective Synthesis
Authors: Tius Marcus A.
Published: October 2013

The stereochemical course of electrocyclic reactions is determined by the orbital symmetry rules. This makes it possible to make predictions of the stereochemical outcome of such carbon–carbon, bond‐forming processes with much greater confidence than can usually be made in the case of reactions proceeding through other mechanisms. Although the potential of these reactions in total synthesis has long been recognized, only recently have the asymmetric catalyzed versions of some of these reactions been developed. A broad overview of this area with emphasis on methods with strong potential in natural products synthesis has been presented in this chapter.
Stereoselective Hydrogenation ofCCBonds: Application to Drug and Natural Product Synthesis
Authors: Andrushko Natalia , Andrushko Vasyl
Published: October 2013

Asymmetric homogeneous hydrogenation is perhaps one of the most researched areas in homogeneous catalysis; thus, it is now used in numerous innovative applications in stereoselective syntheses of many chiral pharmaceutical and natural products. Metal complexes, derived from transition metals, like Rh, Ru, Ir, and so on, and chiral ligands (usually mono‐ or diphosphine ligands), are widely used as catalysts in asymmetric alkene hydrogenation as a result of their efficiency in the preparation of enantiopure compounds with excellent atom economy.

This chapter provides many interesting examples of homogeneous enantio‐ and diastereoselective hydrogenation of CC bonds, highlighting the utility of these methods as useful synthetic tools for the construction of stereogenic centers in stereoselective drug and natural product syntheses.
Asymmetric Hydroamination and Reductive Amination in Total Synthesis
Authors: Ghorai Manas K. , Tiwari Deo Prakash , Bhattacharyya Aditya
Published: October 2013

Asymmetric hydroamination (AHA) and asymmetric reductive amination (ARA) are one of the most popular strategies for enantioselective synthesis of chiral amines, which are very important from a synthetic and a biological point of view.

The addition of the NH bond across an unsaturated CC bond is known as hydroamination. AHA is ideal for industrial processes as it is a 100% atom‐economic reaction and involves readily available substrates. For broadening its scope for a variety of substrates, many metal‐based as well as metal‐free catalytic systems have been developed for asymmetric hydroamination. Along with the synthesis of functionalized chiral amines, AHA has served as a key strategy in the synthesis of the core of various natural products like codeine, pseudodistomin, swainsonine and of drugs like pentazocine.

Reductive amination is a widely used efficient synthetic protocol to install an amine group in place of a carbonyl group in an organic compound. The reaction proceeds through the formation of imine and subsequent one‐pot reduction of it to give the product amine. Use of a metal‐chiral ligand combination, chiral Brønsted acid or chiral organocatalyst, or chiral auxiliary in the reaction can give rise to chiral amine products that are often valuable synthetic intermediatesen routeto many drugs and natural products. Application of these protocols in the total synthesis of drugs and natural products will be discussed along with some experimental procedures.
Cycloadditions with StereoselectiveCNBond Formation in Total Syntheses
Authors: Vincent Guillaume
Published: October 2013

Cycloadditions reactions are very efficient tools for the constructions of multiple bonds in one step and are therefore methods of choice for the total synthesis of natural products and drugs. The use of a terminal nitrogen containing partner allows for the stereoselective formations of a CN bond. Because of the vast number of nitrogen containing compounds available, this field has found a widespread interest in total synthesis. This chapter will cover the cycloadditions in which a CN bond is formed. It will be devoted to the description of [2+2], [3+2], [3+3], [4+2], and [2+2+2] processes that are key steps in total synthesis with imine, nitroso, azo, isocyanate, azomethine imine, azide, or azadiene reagents. A discussion of regioselectivity, diastereoselectivity, and enantioselectivity issues will be provided for each reaction.
Stereoselective Methods for Carbon–Phosphorus (CP) Bond Formation
Authors: Kalek Marcin , Stawinski Jacek
Published: October 2013

A short review of selected chemical methods for the formation of the CP bond and relevant stereochemical aspects for the synthesis of natural products and their analogs containing carbonphosphorus bonds, is given.

Apart from the standard methods, e.g., the Arbuzov, Michaelis‐Becker, Pudovik, Abramov, and Kabachnik‐Fields, their enantioselective versions and modern organo‐ and transition‐metal–catalyzed reactions are discussed in the context of CP bond formation.
Capillary Electrophoresis in Chiral Separations
Authors: Hendrickx Ans , Mangelings Debby , vander Heyden Yvan
Published: October 2013

This chapter starts with an overview of the theory behind capillary electrophoresis and its derived methods. The capillary electrophoresis instrumentation, its separation principle, the theory behind it, and its modes of operation are discussed. This overview is followed by an illustration of the applicability of capillary electrophoresis and its derived techniques in the analysis of chiral compounds using different types of chiral selectors. Some examples are given for each type of chiral selector. Details are provided about the capillaries used, the chiral selectors, and the stationary and mobile phases.
CC Fragmentation: Origins and Recent Applications
Authors: Drahl Michael A. , Manpadi Madhuri , Williams Lawrence J.
Published: October 2013

It has been 60 years since Eschenmoser and Frey disclosed the archetypal CC fragmentation reaction. New fragmentations and several variants of the original quickly followed. Many of these variations, which include the Beckmann, Grob, Wharton, Marshall, and Eschenmoser–Tanabe fragmentations, have been reviewed over the intervening years. A close examination of the origins of fragmentation has not been described. Recently, useful new methods have flourished, particularly fragmentations that give alkynes and allenes, and such reactions have been applied to a range of complex motifs and natural products. This Review traces the origins of fragmentation reactions and provides a summary of the methods, applications, and new insights of heterolytic CC fragmentation reactions advanced over the last 20 years.
Small but Smart: Sensitive Microgel Capsules
Authors: Seiffert Sebastian
Published: October 2013

Microgel capsules are micrometer‐sized particles that consist of a cross‐linked and swollen polymer network complexed with additives. These capsules can be actuated by external stimulation if they are formed from sensitive or supramolecular polymer networks. To make this truly useful, it is crucial to control the microgel size, shape, and loading; this can be achieved by droplet‐based microfluidic templating.
Amythiamicin D and Related Thiopeptides as Inhibitors of the Bacterial Elongation Factor EF‐Tu: Modification of the Amino Acid at Carbon Atom C2 of Ring C Dramatically Influences Activity
Authors: Gross Stefan , Nguyen Fabian , Bierschenk Matthias , Sohmen Daniel , Menzel Thomas , Antes Iris , Wilson Daniel N. , Bach Thorsten
Published: October 2013

Three analogues of amythiamicin D, which differ in the substitution pattern at the methine group adjacent to C2 of the thiazole ring C, were prepared by de novo total synthesis. In amythiamicin D, this carbon atom is (S)‐isopropyl substituted. Two of the new analogues carry a hydroxymethyl in place of the isopropyl group, one at an S‐ (compound 3 a) and the other at an R‐configured stereogenic center (3 b). The third analogue, 3 c, contains a benzyloxymethyl group at an S‐configured stereogenic center. Compounds 3 b and 3 c showed no inhibitory effect toward various bacterial strains, nor did they influence the translation of firefly luciferase. In stark contrast, compound 3 a inhibited the growth of Gram‐positive bacteria Staphylococcus aureus (strains NCTC and Mu50) and Listeria monocytogenes EGD. In the firefly luciferase assay it proved more potent than amythiamicin D, and rescue experiments provided evidence that translation inhibition is due to binding to the bacterial elongation factor Tu (EF‐Tu). The results were rationalized by structural investigations and by molecular dynamics simulations of the free compounds in solution and bound to the EF‐Tu binding site. The low affinity of compound 3 b was attributed to the absence of a critical hydrogen bond, which stabilizes the conformation required for binding to EF‐Tu. Compound 3 c was shown not to comply with the binding properties of the binding site.
Volatility Forecasts: Do Volatility Estimators and Evaluation Methods Matter?
Authors: Jiang I‐Ming , Hung Jui‐Cheng , Wang Chuan‐San
Published: October 2013

This study investigates the volatility forecasting abilities of return‐based and range‐based estimators for two stock indices and two individual stocks in the U.S. stock market. The forecasting performances are evaluated by two robust statistical loss functions, and further by financial applications in risk management and option pricing. Consistent with previous studies, the range‐based volatility forecasts outperform in terms of statistical evaluation, value‐at‐risk calculation, and option pricing. However, return‐based volatility forecasts prove superior in the evaluation of market risk capital requirements. © 2013 Wiley Periodicals, Inc. Jrl Fut Mark 34:1077–1094, 2014
Modified hydrotalcites as a new emerging class of smart additive of reinforced concrete for anticorrosion applications: A literature review
Authors: Yang Z. , Fischer H. , Polder R.
Published: October 2013

Modified hydrotalcites (MTHs) represent a group of technologically promising materials for addition to concrete to improve its durability in aggressive environment, owing to their low cost, relative simplicity of preparation, and plenty of unique composition variables that may be adopted. Up to date, a lot of academic work and commercial interest on MHTs have been invested, but relatively few studies focus on cementitious materials, particularly in exploiting their potential applications in corrosion protection of reinforced concrete structures. In this article, the mechanism of corrosion in reinforced concrete and concrete properties that affect corrosion of reinforcement are briefly introduced. In addition, the existing knowledge with regard to synthesis and characterisation methods of MHTs, ion exchange within the MHT structure as well as the application of MHTs in the cementitious materials were reviewed accordingly. As a new emerging class of smart additive of reinforced concrete, MHTs are expected to contribute to the effort of searching for effective measures to improve the durability of reinforced concrete.
Effect of age‐forming on corrosion properties of an AlZnMgCu alloy
Authors: Chen J. F. , Frankel G. S. , Jiang J. T. , Shao W. Z. , Zhen L.
Published: October 2013

A comparative study of the corrosion properties of an AlZnMgCu alloy subjected to simulate age‐forming (SAF) and traditional aging was performed. The samples pretreated at 160 °C for 24 h using SAF and traditional aging, were immersed in 3.5 wt% sodium chloride solution for up to 96 h, the process of which was monitored by in situ electrochemical impedance spectroscopy (EIS). Optical profilometry measurement shows that the sample subjected to SAF has deeper pits and larger localized corrosion compared with the traditionally aged sample. EIS results suggest that corrosion rate changes with increasing time of immersion, and age forming makes the AlZnMgCu alloy hard to form effective passive film. The larger precipitate and wider precipitate free zone of the sample subjected to simulate age forming were thought to be responsible for the poor corrosion resistance during the immersion test. Additionally, these results suggest that stress during age‐forming increases the grain aspect ratio, which is harmful to intergranular corrosion resistance of the AlZnMgCu alloy.
Coupling mechanism of dew point corrosion and viscous ash deposits
Authors: Liang Z. Y. , Zhao Q. X. , Wang Y. G. , Li Y. X. , Zhang Z. C.
Published: October 2013

Characteristics of the deposits and oxide films formed on 316L stainless steel in situ tested on a boiler of 1000 MW pulverized coal‐fired power plant for 150 h were examined. The results show that the deposits are mainly composed of outer fly ash, middle sulfate, and chloride and fluoride in the inner layer. Oxide films are mainly Fe2O3 and Fe3O4. Two models of coupling mechanism of dew point corrosion and viscous ash deposits at different temperature ranges are proposed to instruct engineering application.
Materials challenges in cyclic carburizing and oxidizing environments for petrochemical applications
Authors: Chun C. M. , Desai S. , Hershkowitz F. , Ramanarayanan T. A.
Published: October 2013

Steam cracking is a petrochemical process that cleaves a broad range of hydrocarbon feed molecules into a variety of light olefinic products, including the highly desirable ethylene. Over the course of a cracking operation using a feed mixture of a saturated hydrocarbon and steam around 900–1000 °C in tubular alloy coils located in fired heaters, coke inevitably forms on the inside surfaces of the furnace tubes and must be burned off and/or spalled off periodically using steam or a steam–air mixture. Furnace tube materials are predominantly based on chromia‐forming alloys; such alloys can degrade by carburization and oxide–carbide conversion in such a mixed carburizing–oxidizing environment. These hurdles have been largely overcome by using an alumina‐forming material that provides superior corrosion and coking resistance. Cracking hydrocarbons at much higher temperatures results in high selectivity to acetylene, which can be converted into many petrochemical products including ethylene. The desired hydropyrolysis reaction from hydrocarbons to acetylene can be realized in a reverse‐flow reactor operating above 1500 °C in a scaleable manner. The reactor elements include ceramic components that are placed in the hottest regions of the reactor, and must withstand temperatures in the range of 1500–2000 °C. Moreover, the materials in the hot zone are exposed alternately to a regeneration (heat addition) step that is mildly oxidizing and a pyrolysis (cracking) step that is strongly reducing with a correspondingly high carbon activity. This paper addresses the thermodynamic stability of selected ceramic materials based on alumina, zirconia, and yttria for such an application. Results from laboratory tests involving the exposure of these ceramic materials to simulated process conditions followed by their microstructural characterization are compared with expectations from thermodynamic predictions.
Influence of water vapour on the oxidation behaviour of a conventional aluminide and a new thermal barrier coating system sintered from a slurry
Authors: Brossard M. , Bouchaud B. , Pedraza F.
Published: October 2013

In this work, the effect of water vapour on a new thermal barrier coating system synthesised from a slurry containing Al microparticles was studied under isothermal regime at 1100 °C for short oxidation times (50 h). Both dry air and argon gas atmospheres were investigated with increasing water vapour contents (0, 5, 10% RH, relative humidity) and the oxidation mechanisms and growth kinetics of the oxide scales were compared to conventional aluminide coatings up to 50% RH. The phase transformations occurring in the coating were characterised by local Raman micro‐spectrometry with complementary analytical techniques (X‐ray diffraction and FEG‐ESEM/EDS). The results demonstrated that water vapour does not exert a great influence on the oxidation of this type of coatings once an α‐Al2O3 scale is stabilised after an appropriate sintering of the coating. In contrast the combined effect of water vapour and oxidation onto oxide scales grown from raw aluminide coatings was shown to trigger delayed transformation of θ into α‐Al2O3, the appearance of pores and spallation, in particular in air + x %RH.